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Sunday, October 27, 2019

Diabetes management

From Wikipedia, the free encyclopedia
 
The term diabetes includes several different metabolic disorders that all, if left untreated, result in abnormally high concentration of a sugar called glucose in the blood. Diabetes mellitus type 1 results when the pancreas no longer produces significant amounts of the hormone insulin, usually owing to the autoimmune destruction of the insulin-producing beta cells of the pancreas. Diabetes mellitus type 2, in contrast, is now thought to result from autoimmune attacks on the pancreas and/or insulin resistance. The pancreas of a person with type 2 diabetes may be producing normal or even abnormally large amounts of insulin. Other forms of diabetes mellitus, such as the various forms of maturity onset diabetes of the young, may represent some combination of insufficient insulin production and insulin resistance. Some degree of insulin resistance may also be present in a person with type 1 diabetes.

The main goal of diabetes management is, as far as possible, to restore carbohydrate metabolism to a normal state. To achieve this goal, individuals with an absolute deficiency of insulin require insulin replacement therapy, which is given through injections or an insulin pump. Insulin resistance, in contrast, can be corrected by dietary modifications and exercise. Other goals of diabetes management are to prevent or treat the many complications that can result from the disease itself and from its treatment.

Overview

Goals

The treatment goals are related to effective control of blood glucose, blood pressure and lipids, to minimize the risk of long-term consequences associated with diabetes. They are suggested in clinical practice guidelines released by various national and international diabetes agencies. 

The targets are:
  • HbA1c of less than 6% or 7.0% if they are achievable without significant hypoglycemia
  • Preprandial blood glucose: 3.9 to 7.2 mmol/L (70 to 130 mg/dl)
  • 2-hour postprandial blood glucose: <10 dl="" mg="" mmol="" nbsp="" span="">
Goals should be individualized based on:
In older patients, clinical practice guidelines by the American Geriatrics Society states "for frail older adults, persons with life expectancy of less than 5 years, and others in whom the risks of intensive glycemic control appear to outweigh the benefits, a less stringent target such as HbA1c of 8% is appropriate".

Issues

The primary issue requiring management is that of the glucose cycle. In this, glucose in the bloodstream is made available to cells in the body; a process dependent upon the twin cycles of glucose entering the bloodstream, and insulin allowing appropriate uptake into the body cells. Both aspects can require management. Another issue that ties along with the glucose cycle is getting a balanced amount of the glucose to the major organs so they are not affected negatively.

Complexities

Daily glucose and insulin cycle

The main complexities stem from the nature of the feedback loop of the glucose cycle, which is sought to be regulated:
  • The glucose cycle is a system which is affected by two factors: entry of glucose into the bloodstream and also blood levels of insulin to control its transport out of the bloodstream
  • As a system, it is sensitive to diet and exercise
  • It is affected by the need for user anticipation due to the complicating effects of time delays between any activity and the respective impact on the glucose system
  • Management is highly intrusive, and compliance is an issue, since it relies upon user lifestyle change and often upon regular sampling and measuring of blood glucose levels, multiple times a day in many cases
  • It changes as people grow and develop
  • It is highly individual
As diabetes is a prime risk factor for cardiovascular disease, controlling other risk factors which may give rise to secondary conditions, as well as the diabetes itself, is one of the facets of diabetes management. Checking cholesterol, LDL, HDL and triglyceride levels may indicate hyperlipoproteinemia, which may warrant treatment with hypolipidemic drugs. Checking the blood pressure and keeping it within strict limits (using diet and antihypertensive treatment) protects against the retinal, renal and cardiovascular complications of diabetes. Regular follow-up by a podiatrist or other foot health specialists is encouraged to prevent the development of diabetic foot. Annual eye exams are suggested to monitor for progression of diabetic retinopathy.

Early advancements

Late in the 19th century, sugar in the urine (glycosuria) was associated with diabetes. Various doctors studied the connection. Frederick Madison Allen studied diabetes in 1909–12, then published a large volume, Studies Concerning Glycosuria and Diabetes, (Boston, 1913). He invented a fasting treatment for diabetes called the Allen treatment for diabetes. His diet was an early attempt at managing diabetes.

Blood sugar level

Blood sugar level is measured by means of a glucose meter, with the result either in mg/dL (milligrams per deciliter in the US) or mmol/L (millimoles per litre in Canada and Eastern Europe) of blood. The average normal person has an average fasting glucose level of 4.5 mmol/L (81 mg/dL), with a lows of down to 2.5 and up to 5.4 mmol/L (65 to 98 mg/dL).

Optimal management of diabetes involves patients measuring and recording their own blood glucose levels. By keeping a diary of their own blood glucose measurements and noting the effect of food and exercise, patients can modify their lifestyle to better control their diabetes. For patients on insulin, patient involvement is important in achieving effective dosing and timing.

Hypo and hyperglycemia

Levels which are significantly above or below this range are problematic and can in some cases be dangerous. A level of <3 .8="" a="" as="" described="" dl="" i="" is="" mg="" mmol="" nbsp="" usually="">hypoglycemic attack
(low blood sugar). Most diabetics know when they are going to "go hypo" and usually are able to eat some food or drink something sweet to raise levels. A patient who is hyperglycemic (high glucose) can also become temporarily hypoglycemic, under certain conditions (e.g. not eating regularly, or after strenuous exercise, followed by fatigue). Intensive efforts to achieve blood sugar levels close to normal have been shown to triple the risk of the most severe form of hypoglycemia, in which the patient requires assistance from by-standers in order to treat the episode. In the United States, there were annually 48,500 hospitalizations for diabetic hypoglycemia and 13,100 for diabetic hypoglycemia resulting in coma in the period 1989 to 1991, before intensive blood sugar control was as widely recommended as today. One study found that hospital admissions for diabetic hypoglycemia increased by 50% from 1990–1993 to 1997–2000, as strict blood sugar control efforts became more common. Among intensively controlled type 1 diabetics, 55% of episodes of severe hypoglycemia occur during sleep, and 6% of all deaths in diabetics under the age of 40 are from nocturnal hypoglycemia in the so-called 'dead-in-bed syndrome,' while National Institute of Health statistics show that 2% to 4% of all deaths in diabetics are from hypoglycemia. In children and adolescents following intensive blood sugar control, 21% of hypoglycemic episodes occurred without explanation. In addition to the deaths caused by diabetic hypoglycemia, periods of severe low blood sugar can also cause permanent brain damage. Although diabetic nerve disease is usually associated with hyperglycemia, hypoglycemia as well can initiate or worsen neuropathy in diabetics intensively struggling to reduce their hyperglycemia.

Levels greater than 13–15 mmol/L (230–270 mg/dL) are considered high, and should be monitored closely to ensure that they reduce rather than continue to remain high. The patient is advised to seek urgent medical attention as soon as possible if blood sugar levels continue to rise after 2–3 tests. High blood sugar levels are known as hyperglycemia, which is not as easy to detect as hypoglycemia and usually happens over a period of days rather than hours or minutes. If left untreated, this can result in diabetic coma and death. 

A blood glucose test strip for an older style (i.e., optical color sensing) monitoring system
 
Prolonged and elevated levels of glucose in the blood, which is left unchecked and untreated, will, over time, result in serious diabetic complications in those susceptible and sometimes even death. There is currently no way of testing for susceptibility to complications. Diabetics are therefore recommended to check their blood sugar levels either daily or every few days. There is also diabetes management software available from blood testing manufacturers which can display results and trends over time. Type 1 diabetics normally check more often, due to insulin therapy. 

A history of blood sugar level results is especially useful for the diabetic to present to their doctor or physician in the monitoring and control of the disease. Failure to maintain a strict regimen of testing can accelerate symptoms of the condition, and it is therefore imperative that any diabetic patient strictly monitor their glucose levels regularly.

Glycemic control

Glycemic control is a medical term referring to the typical levels of blood sugar (glucose) in a person with diabetes mellitus. Much evidence suggests that many of the long-term complications of diabetes, especially the microvascular complications, result from many years of hyperglycemia (elevated levels of glucose in the blood). Good glycemic control, in the sense of a "target" for treatment, has become an important goal of diabetes care, although recent research suggests that the complications of diabetes may be caused by genetic factors or, in type 1 diabetics, by the continuing effects of the autoimmune disease which first caused the pancreas to lose its insulin-producing ability.

Because blood sugar levels fluctuate throughout the day and glucose records are imperfect indicators of these changes, the percentage of hemoglobin which is glycosylated is used as a proxy measure of long-term glycemic control in research trials and clinical care of people with diabetes. This test, the hemoglobin A1c or glycosylated hemoglobin reflects average glucoses over the preceding 2–3 months. In nondiabetic persons with normal glucose metabolism the glycosylated hemoglobin is usually 4–6% by the most common methods (normal ranges may vary by method). 

"Perfect glycemic control" would mean that glucose levels were always normal (70–130 mg/dl, or 3.9–7.2 mmol/L) and indistinguishable from a person without diabetes. In reality, because of the imperfections of treatment measures, even "good glycemic control" describes blood glucose levels that average somewhat higher than normal much of the time. In addition, one survey of type 2 diabetics found that they rated the harm to their quality of life from intensive interventions to control their blood sugar to be just as severe as the harm resulting from intermediate levels of diabetic complications.

In the 1990s the American Diabetes Association conducted a publicity campaign to persuade patients and physicians to strive for average glucose and hemoglobin A1c values below 200 mg/dl (11 mmol/l) and 8%. Currently many patients and physicians attempt to do better than that. 

As of 2015 the guidelines called for an HbA1c of around 7% or a fasting glucose of less than 7.2 mmol/L (130 mg/dL); however these goals may be changed after professional clinical consultation, taking into account particular risks of hypoglycemia and life expectancy. Despite guidelines recommending that intensive blood sugar control be based on balancing immediate harms and long-term benefits, many people – for example people with a life expectancy of less than nine years – who will not benefit are over-treated and do not experience clinically meaningful benefits.

Poor glycemic control refers to persistently elevated blood glucose and glycosylated hemoglobin levels, which may range from 200–500 mg/dl (11–28 mmol/L) and 9–15% or higher over months and years before severe complications occur. Meta-analysis of large studies done on the effects of tight vs. conventional, or more relaxed, glycemic control in type 2 diabetics have failed to demonstrate a difference in all-cause cardiovascular death, non-fatal stroke, or limb amputation, but decreased the risk of nonfatal heart attack by 15%. Additionally, tight glucose control decreased the risk of progression of retinopathy and nephropathy, and decreased the incidence peripheral neuropathy, but increased the risk of hypoglycemia 2.4 times.

Monitoring

A modern portable blood glucose meter (OneTouch Ultra), displaying a reading of 5.4 mmol/L (98 mg/dL).
 
Relying on their own perceptions of symptoms of hyperglycemia or hypoglycemia is usually unsatisfactory as mild to moderate hyperglycemia causes no obvious symptoms in nearly all patients. Other considerations include the fact that, while food takes several hours to be digested and absorbed, insulin administration can have glucose lowering effects for as little as 2 hours or 24 hours or more (depending on the nature of the insulin preparation used and individual patient reaction). In addition, the onset and duration of the effects of oral hypoglycemic agents vary from type to type and from patient to patient.

Personal (home) glucose monitoring

Control and outcomes of both types 1 and 2 diabetes may be improved by patients using home glucose meters to regularly measure their glucose levels. Glucose monitoring is both expensive (largely due to the cost of the consumable test strips) and requires significant commitment on the part of the patient. Lifestyle adjustments are generally made by the patients themselves following training by a clinician.

Regular blood testing, especially in type 1 diabetics, is helpful to keep adequate control of glucose levels and to reduce the chance of long term side effects of the disease. There are many (at least 20+) different types of blood monitoring devices available on the market today; not every meter suits all patients and it is a specific matter of choice for the patient, in consultation with a physician or other experienced professional, to find a meter that they personally find comfortable to use. The principle of the devices is virtually the same: a small blood sample is collected and measured. In one type of meter, the electrochemical, a small blood sample is produced by the patient using a lancet (a sterile pointed needle). The blood droplet is usually collected at the bottom of a test strip, while the other end is inserted in the glucose meter. This test strip contains various chemicals so that when the blood is applied, a small electrical charge is created between two contacts. This charge will vary depending on the glucose levels within the blood. In older glucose meters, the drop of blood is placed on top of a strip. A chemical reaction occurs and the strip changes color. The meter then measures the color of the strip optically. 

Self-testing is clearly important in type I diabetes where the use of insulin therapy risks episodes of hypoglycemia and home-testing allows for adjustment of dosage on each administration. Its benefit in type 2 diabetes has been more controversial, but recent studies have resulted in guidance that self-monitoring does not improve blood glucose or quality of life. 

Benefits of control and reduced hospital admission have been reported. However, patients on oral medication who do not self-adjust their drug dosage will miss many of the benefits of self-testing, and so it is questionable in this group. This is particularly so for patients taking monotherapy with metformin who are not at risk of hypoglycaemia. Regular 6 monthly laboratory testing of HbA1c (glycated haemoglobin) provides some assurance of long-term effective control and allows the adjustment of the patient's routine medication dosages in such cases. High frequency of self-testing in type 2 diabetes has not been shown to be associated with improved control. The argument is made, though, that type 2 patients with poor long term control despite home blood glucose monitoring, either have not had this integrated into their overall management, or are long overdue for tighter control by a switch from oral medication to injected insulin.

Continuous Glucose Monitoring (CGM) CGM technology has been rapidly developing to give people living with diabetes an idea about the speed and direction of their glucose changes. While it still requires calibration from SMBG and is not indicated for use in correction boluses, the accuracy of these monitors is increasing with every innovation. The Libre Blood Sugar Diet Program utilizes the CGM and Libre Sensor and by collecting all the data through a smart phone and smart watch experts analyze this data 24/7 in Real Time. The results are that certain foods can be identified as causing one's blood sugar levels to rise and other foods as safe foods- that do not make a person's blood sugar levels to rise. Each individual absorbs sugar differently and this is why testing is a necessity.

HbA1c test

A useful test that has usually been done in a laboratory is the measurement of blood HbA1c levels. This is the ratio of glycated hemoglobin in relation to the total hemoglobin. Persistent raised plasma glucose levels cause the proportion of these molecules to go up. This is a test that measures the average amount of diabetic control over a period originally thought to be about 3 months (the average red blood cell lifetime), but more recently thought to be more strongly weighted to the most recent 2 to 4 weeks. In the non-diabetic, the HbA1c level ranges from 4.0–6.0%; patients with diabetes mellitus who manage to keep their HbA1c level below 6.5% are considered to have good glycemic control. The HbA1c test is not appropriate if there has been changes to diet or treatment within shorter time periods than 6 weeks or there is disturbance of red cell aging (e.g. recent bleeding or hemolytic anemia) or a hemoglobinopathy (e.g. sickle cell disease). In such cases the alternative Fructosamine test is used to indicate average control in the preceding 2 to 3 weeks.

Continuous glucose monitoring

The first CGM device made available to consumers was the GlucoWatch biographer in 1999. This product is no longer sold. It was a retrospective device rather than live. Several live monitoring devices have subsequently been manufactured which provide ongoing monitoring of glucose levels on an automated basis during the day.

Lifestyle modification

The British National Health Service launched a programme targeting 100,000 people at risk of diabetes to lose weight and take more exercise in 2016. In 2019 it was announced that the programme was successful. The 17,000 people who attended most of the healthy living sessions had, collectively lost nearly 60,000 kg, and the programme was to be doubled in size.

Diet

Because high blood sugar caused by poorly controlled diabetes can lead to a plethora of immediate and long-term complications, it is critical to maintain blood sugars as close to normal as possible, and a diet that produces more controllable glycemic variability is an important factor in producing normal blood sugars.

People with type 1 diabetes who use insulin can eat whatever they want, preferably a healthy diet with some carbohydrate content; in the long term it is helpful to eat a consistent amount of carbohydrate to make blood sugar management easier.

There is a lack of evidence of the usefulness of low-carbohydrate dieting for people with type 1 diabetes. Although for certain individuals it may be feasible to follow a low-carbohydrate regime combined with carefully-managed insulin dosing, this is hard to maintain and there are concerns about potential adverse health effects caused by the diet. In general people with type 1 diabetes are advised to follow an individualized eating plan rather than a pre-decided one.

Medications

Currently, one goal for diabetics is to avoid or minimize chronic diabetic complications, as well as to avoid acute problems of hyperglycemia or hypoglycemia. Adequate control of diabetes leads to lower risk of complications associated with unmonitored diabetes including kidney failure (requiring dialysis or transplant), blindness, heart disease and limb amputation. The most prevalent form of medication is hypoglycemic treatment through either oral hypoglycemics and/or insulin therapy. There is emerging evidence that full-blown diabetes mellitus type 2 can be evaded in those with only mildly impaired glucose tolerance.

Patients with type 1 diabetes mellitus require direct injection of insulin as their bodies cannot produce enough (or even any) insulin. As of 2010, there is no other clinically available form of insulin administration other than injection for patients with type 1: injection can be done by insulin pump, by jet injector, or any of several forms of hypodermic needle. Non-injective methods of insulin administration have been unattainable as the insulin protein breaks down in the digestive tract. There are several insulin application mechanisms under experimental development as of 2004, including a capsule that passes to the liver and delivers insulin into the bloodstream. There have also been proposed vaccines for type I using glutamic acid decarboxylase (GAD), but these are currently not being tested by the pharmaceutical companies that have sublicensed the patents to them.

For type 2 diabetics, diabetic management consists of a combination of diet, exercise, and weight loss, in any achievable combination depending on the patient. Obesity is very common in type 2 diabetes and contributes greatly to insulin resistance. Weight reduction and exercise improve tissue sensitivity to insulin and allow its proper use by target tissues. Patients who have poor diabetic control after lifestyle modifications are typically placed on oral hypoglycemics. Some Type 2 diabetics eventually fail to respond to these and must proceed to insulin therapy. A study conducted in 2008 found that increasingly complex and costly diabetes treatments are being applied to an increasing population with type 2 diabetes. Data from 1994 to 2007 was analyzed and it was found that the mean number of diabetes medications per treated patient increased from 1.14 in 1994 to 1.63 in 2007.

Patient education and compliance with treatment is very important in managing the disease. Improper use of medications and insulin can be very dangerous causing hypo- or hyper-glycemic episodes.

Insulin

Insulin pen used to administer insulin
 
For type 1 diabetics, there will always be a need for insulin injections throughout their life, as the pancreatic beta cells of a type 1 diabetic are not capable of producing sufficient insulin. However, both type 1 and type 2 diabetics can see dramatic improvements in blood sugars through modifying their diet, and some type 2 diabetics can fully control the disease by dietary modification.

Insulin therapy requires close monitoring and a great deal of patient education, as improper administration is quite dangerous. For example, when food intake is reduced, less insulin is required. A previously satisfactory dosing may be too much if less food is consumed causing a hypoglycemic reaction if not intelligently adjusted. Exercise decreases insulin requirements as exercise increases glucose uptake by body cells whose glucose uptake is controlled by insulin, and vice versa. In addition, there are several types of insulin with varying times of onset and duration of action.

Several companies are currently working to develop a non-invasive version of insulin, so that injections can be avoided. Mannkind has developed an inhalable version, while companies like Novo Nordisk, Oramed and BioLingus have efforts undergoing for an oral product. Also oral combination products of insulin and a GLP-1 agonist are being developed. 

Insulin therapy creates risk because of the inability to continuously know a person's blood glucose level and adjust insulin infusion appropriately. New advances in technology have overcome much of this problem. Small, portable insulin infusion pumps are available from several manufacturers. They allow a continuous infusion of small amounts of insulin to be delivered through the skin around the clock, plus the ability to give bolus doses when a person eats or has elevated blood glucose levels. This is very similar to how the pancreas works, but these pumps lack a continuous "feed-back" mechanism. Thus, the user is still at risk of giving too much or too little insulin unless blood glucose measurements are made.

A further danger of insulin treatment is that while diabetic microangiopathy is usually explained as the result of hyperglycemia, studies in rats indicate that the higher than normal level of insulin diabetics inject to control their hyperglycemia may itself promote small blood vessel disease. While there is no clear evidence that controlling hyperglycemia reduces diabetic macrovascular and cardiovascular disease, there are indications that intensive efforts to normalize blood glucose levels may worsen cardiovascular and cause diabetic mortality.

Driving

Paramedics in Southern California attend a diabetic man who lost effective control of his vehicle due to low blood sugar (hypoglycemia) and drove it over the curb and into the water main and backflow valve in front of this industrial building. He was not injured, but required emergency intravenous glucose.
 
Studies conducted in the United States and Europe showed that drivers with type 1 diabetes had twice as many collisions as their non-diabetic spouses, demonstrating the increased risk of driving collisions in the type 1 diabetes population. Diabetes can compromise driving safety in several ways. First, long-term complications of diabetes can interfere with the safe operation of a vehicle. For example, diabetic retinopathy (loss of peripheral vision or visual acuity), or peripheral neuropathy (loss of feeling in the feet) can impair a driver’s ability to read street signs, control the speed of the vehicle, apply appropriate pressure to the brakes, etc.

Second, hypoglycemia can affect a person’s thinking process, coordination, and state of consciousness. This disruption in brain functioning is called neuroglycopenia. Studies have demonstrated that the effects of neuroglycopenia impair driving ability. A study involving people with type 1 diabetes found that individuals reporting two or more hypoglycemia-related driving mishaps differ physiologically and behaviorally from their counterparts who report no such mishaps. For example, during hypoglycemia, drivers who had two or more mishaps reported fewer warning symptoms, their driving was more impaired, and their body released less epinephrine (a hormone that helps raise BG). Additionally, individuals with a history of hypoglycemia-related driving mishaps appear to use sugar at a faster rate and are relatively slower at processing information. These findings indicate that although anyone with type 1 diabetes may be at some risk of experiencing disruptive hypoglycemia while driving, there is a subgroup of type 1 drivers who are more vulnerable to such events. 

Given the above research findings, it is recommended that drivers with type 1 diabetes with a history of driving mishaps should never drive when their BG is less than 70 mg/dl (3.9 mmol/l). Instead, these drivers are advised to treat hypoglycemia and delay driving until their BG is above 90 mg/dl (5 mmol/l). Such drivers should also learn as much as possible about what causes their hypoglycemia, and use this information to avoid future hypoglycemia while driving.

Studies funded by the National Institutes of Health (NIH) have demonstrated that face-to-face training programs designed to help individuals with type 1 diabetes better anticipate, detect, and prevent extreme BG can reduce the occurrence of future hypoglycemia-related driving mishaps. An internet-version of this training has also been shown to have significant beneficial results. Additional NIH funded research to develop internet interventions specifically to help improve driving safety in drivers with type 1 diabetes is currently underway.

Exenatide

The U.S. Food and Drug Administration (FDA) has approved a treatment called Exenatide, based on the saliva of a Gila monster, to control blood sugar in patients with type 2 diabetes.

Other regimens

Artificial Intelligence researcher Dr. Cynthia Marling, of the Ohio University Russ College of Engineering and Technology, in collaboration with the Appalachian Rural Health Institute Diabetes Center, is developing a case based reasoning system to aid in diabetes management. The goal of the project is to provide automated intelligent decision support to diabetes patients and their professional care providers by interpreting the ever-increasing quantities of data provided by current diabetes management technology and translating it into better care without time consuming manual effort on the part of an endocrinologist or diabetologist. This type of Artificial Intelligence-based treatment shows some promise with initial testing of a prototype system producing best practice treatment advice which anaylizing physicians deemed to have some degree of benefit over 70% of the time and advice of neutral benefit another nearly 25% of the time.

Use of a "Diabetes Coach" is becoming an increasingly popular way to manage diabetes. A Diabetes Coach is usually a Certified diabetes educator (CDE) who is trained to help people in all aspects of caring for their diabetes. The CDE can advise the patient on diet, medications, proper use of insulin injections and pumps, exercise, and other ways to manage diabetes while living a healthy and active lifestyle. CDEs can be found locally or by contacting a company which provides personalized diabetes care using CDEs. Diabetes Coaches can speak to a patient on a pay-per-call basis or via a monthly plan.

Dental care

High blood glucose in diabetic people is a risk factor for developing gum and tooth problems, especially in post-puberty and aging individuals. Diabetic patients have greater chances of developing oral health problems such as tooth decay, salivary gland dysfunction, fungal infections, inflammatory skin disease, periodontal disease or taste impairment and thrush of the mouth. The oral problems in persons suffering from diabetes can be prevented with a good control of the blood sugar levels, regular check-ups and a very good oral hygiene. By maintaining a good oral status, diabetic persons prevent losing their teeth as a result of various periodontal conditions.

Diabetic persons must increase their awareness about oral infections as they have a double impact on health. Firstly, people with diabetes are more likely to develop periodontal disease, which causes increased blood sugar levels, often leading to diabetes complications. Severe periodontal disease can increase blood sugar, contributing to increased periods of time when the body functions with a high blood sugar. This puts diabetics at increased risk for diabetic complications.

The first symptoms of gum and tooth infection in diabetic persons are decreased salivary flow and burning mouth or tongue. Also, patients may experience signs like dry mouth, which increases the incidence of decay. Poorly controlled diabetes usually leads to gum recession, since plaque creates more harmful proteins in the gums.

Tooth decay and cavities are some of the first oral problems that individuals with diabetes are at risk for. Increased blood sugar levels translate into greater sugars and acids that attack the teeth and lead to gum diseases. Gingivitis can also occur as a result of increased blood sugar levels along with an inappropriate oral hygiene. Periodontitis is an oral disease caused by untreated gingivitis and which destroys the soft tissue and bone that support the teeth. This disease may cause the gums to pull away from the teeth which may eventually loosen and fall out. Diabetic people tend to experience more severe periodontitis because diabetes lowers the ability to resist infection and also slows healing. At the same time, an oral infection such as periodontitis can make diabetes more difficult to control because it causes the blood sugar levels to rise.

To prevent further diabetic complications as well as serious oral problems, diabetic persons must keep their blood sugar levels under control and have a proper oral hygiene. A study in the Journal of Periodontology found that poorly controlled type 2 diabetic patients are more likely to develop periodontal disease than well-controlled diabetics are. At the same time, diabetic patients are recommended to have regular checkups with a dental care provider at least once in three to four months. Diabetics who receive good dental care and have good insulin control typically have a better chance at avoiding gum disease to help prevent tooth loss.

Dental care is therefore even more important for diabetic patients than for healthy individuals. Maintaining the teeth and gum healthy is done by taking some preventing measures such as regular appointments at a dentist and a very good oral hygiene. Also, oral health problems can be avoided by closely monitoring the blood sugar levels. Patients who keep better under control their blood sugar levels and diabetes are less likely to develop oral health problems when compared to diabetic patients who control their disease moderately or poorly. 

Poor oral hygiene is a great factor to take under consideration when it comes to oral problems and even more in people with diabetes. Diabetic people are advised to brush their teeth at least twice a day, and if possible, after all meals and snacks. However, brushing in the morning and at night is mandatory as well as flossing and using an anti-bacterial mouthwash. Individuals who suffer from diabetes are recommended to use toothpaste that contains fluoride as this has proved to be the most efficient in fighting oral infections and tooth decay. Flossing must be done at least once a day, as well because it is helpful in preventing oral problems by removing the plaque between the teeth, which is not removed when brushing.

Diabetic patients must get professional dental cleanings every six months. In cases when dental surgery is needed, it is necessary to take some special precautions such as adjusting diabetes medication or taking antibiotics to prevent infection. Looking for early signs of gum disease (redness, swelling, bleeding gums) and informing the dentist about them is also helpful in preventing further complications. Quitting smoking is recommended to avoid serious diabetes complications and oral diseases. 

Diabetic persons are advised to make morning appointments to the dental care provider as during this time of the day the blood sugar levels tend to be better kept under control. Not least, individuals who suffer from diabetes must make sure both their physician and dental care provider are informed and aware of their condition, medical history and periodontal status.

Medication nonadherence

Because many patients with diabetes have two or more comorbidities, they often require multiple medications. The prevalence of medication nonadherence is high among patients with chronic conditions, such as diabetes, and nonadherence is associated with public health issues and higher health care costs. One reason for nonadherence is the cost of medications. Being able to detect cost-related nonadherence is important for health care professionals, because this can lead to strategies to assist patients with problems paying for their medications. Some of these strategies are use of generic drugs or therapeutic alternatives, substituting a prescription drug with an over-the-counter medication, and pill-splitting. Interventions to improve adherence can achieve reductions in diabetes morbidity and mortality, as well as significant cost savings to the health care system. Smartphone apps have been found to improve self-management and health outcomes in people with diabetes through functions such as specific reminder alarms, while working with mental health professionals has also been found to help people with diabetes develop the skills to manage their medications and challenges of self-management effectively.

Psychological mechanisms and adherence

As self-management of diabetes typically involves lifestyle modifications, adherence may pose a significant self-management burden on many individuals. For example, individuals with diabetes may find themselves faced with the need to self-monitor their blood glucose levels, adhere to healthier diets and maintain exercise regimens regularly in order to maintain metabolic control and reduce the risk of developing cardiovascular problems. Barriers to adherence have been associated with key psychological mechanisms: knowledge of self-management, beliefs about the efficacy of treatment and self-efficacy/perceived control. Such mechanisms are inter-related, as one's thoughts (e.g. one's perception of diabetes, or one's appraisal of how helpful self-management is) is likely to relate to one's emotions (e.g. motivation to change), which in turn, affects one's self-efficacy (one's confidence in their ability to engage in a behaviour to achieve a desired outcome).

As diabetes management is affected by an individual's emotional and cognitive state, there has been evidence suggesting the self-management of diabetes is negatively affected by diabetes-related distress and depression. There is growing evidence that there is higher levels of clinical depression in patients with diabetes compared to the non-diabetic population. Depression in individuals with diabetes has been found to be associated with poorer self-management of symptoms. This suggests that it may be important to target mood in treatment.

To this end, treatment programs such as the Cognitive Behavioural Therapy - Adherence and Depression program (CBT-AD) have been developed to target the psychological mechanisms underpinning adherence. By working on increasing motivation and challenging maladaptive illness perceptions, programs such as CBT-AD aim to enhance self-efficacy and improve diabetes-related distress and one's overall quality of life.

Research

Type 1 diabetes

Diabetes type 1 is caused by the destruction of enough beta cells to produce symptoms; these cells, which are found in the Islets of Langerhans in the pancreas, produce and secrete insulin, the single hormone responsible for allowing glucose to enter from the blood into cells (in addition to the hormone amylin, another hormone required for glucose homeostasis). Hence, the phrase "curing diabetes type 1" means "causing a maintenance or restoration of the endogenous ability of the body to produce insulin in response to the level of blood glucose" and cooperative operation with counterregulatory hormones. 

This section deals only with approaches for curing the underlying condition of diabetes type 1, by enabling the body to endogenously, in vivo, produce insulin in response to the level of blood glucose. It does not cover other approaches, such as, for instance, closed-loop integrated glucometer/insulin pump products, which could potentially increase the quality-of-life for some who have diabetes type 1, and may by some be termed "artificial pancreas".

Encapsulation approach

The Bio-artificial pancreas: a cross section of bio-engineered tissue with encapsulated islet cells delivering endocrine hormones in response to glucose
 
A biological approach to the artificial pancreas is to implant bioengineered tissue containing islet cells, which would secrete the amounts of insulin, amylin and glucagon needed in response to sensed glucose.

When islet cells have been transplanted via the Edmonton protocol, insulin production (and glycemic control) was restored, but at the expense of continued immunosuppression drugs. Encapsulation of the islet cells in a protective coating has been developed to block the immune response to transplanted cells, which relieves the burden of immunosuppression and benefits the longevity of the transplant.

Stem cells

Research is being done at several locations in which islet cells are developed from stem cells

Stem cell research has also been suggested as a potential avenue for a cure since it may permit regrowth of Islet cells which are genetically part of the treated individual, thus perhaps eliminating the need for immuno-suppressants.[48] This new method autologous nonmyeloablative hematopoietic stem cell transplantation was developed by a research team composed by Brazilian and American scientists (Dr. Julio Voltarelli, Dr. Carlos Eduardo Couri, Dr Richard Burt, and colleagues) and it was the first study to use stem cell therapy in human diabetes mellitus This was initially tested in mice and in 2007 there was the first publication of stem cell therapy to treat this form of diabetes. Until 2009, there was 23 patients included and followed for a mean period of 29.8 months (ranging from 7 to 58 months). In the trial, severe immunosuppression with high doses of cyclophosphamide and anti-thymocyte globulin is used with the aim of "turning off" the immunologic system", and then autologous hematopoietic stem cells are reinfused to regenerate a new one. In summary it is a kind of "immunologic reset" that blocks the autoimmune attack against residual pancreatic insulin-producing cells. Until December 2009, 12 patients remained continuously insulin-free for periods ranging from 14 to 52 months and 8 patients became transiently insulin-free for periods ranging from 6 to 47 months. Of these last 8 patients, 2 became insulin-free again after the use of sitagliptin, a DPP-4 inhibitor approved only to treat type 2 diabetic patients and this is also the first study to document the use and complete insulin-independendce in humans with type 1 diabetes with this medication. In parallel with insulin suspension, indirect measures of endogenous insulin secretion revealed that it significantly increased in the whole group of patients, regardless the need of daily exogenous insulin use.

Gene therapy

Gene therapy: Designing a viral vector to deliberately infect cells with DNA to carry on the viral production of insulin in response to the blood sugar level.
 
Technology for gene therapy is advancing rapidly such that there are multiple pathways possible to support endocrine function, with potential to practically cure diabetes.
  • Gene therapy can be used to manufacture insulin directly: an oral medication, consisting of viral vectors containing the insulin sequence, is digested and delivers its genes to the upper intestines. Those intestinal cells will then behave like any viral infected cell, and will reproduce the insulin protein. The virus can be controlled to infect only the cells which respond to the presence of glucose, such that insulin is produced only in the presence of high glucose levels. Due to the limited numbers of vectors delivered, very few intestinal cells would actually be impacted and would die off naturally in a few days. Therefore, by varying the amount of oral medication used, the amount of insulin created by gene therapy can be increased or decreased as needed. As the insulin-producing intestinal cells die off, they are boosted by additional oral medications.
  • Gene therapy might eventually be used to cure the cause of beta cell destruction, thereby curing the new diabetes patient before the beta cell destruction is complete and irreversible.
  • Gene therapy can be used to turn duodenum cells and duodenum adult stem cells into beta cells which produce insulin and amylin naturally. By delivering beta cell DNA to the intestine cells in the duodenum, a few intestine cells will turn into beta cells, and subsequently adult stem cells will develop into beta cells. This makes the supply of beta cells in the duodenum self replenishing, and the beta cells will produce insulin in proportional response to carbohydrates consumed.

Type 2 diabetes

Type 2 diabetes is usually first treated by increasing physical activity, and eliminating saturated fat and reducing sugar and carbohydrate intake with a goal of losing weight. These can restore insulin sensitivity even when the weight loss is modest, for example around 5 kg (10 to 15 lb), most especially when it is in abdominal fat deposits. Diets that are very low in saturated fats have been claimed to reverse insulin resistance.

Cognitive Behavioural Therapy is an effective intervention for improving adherence to medication, depression and glycaemic control, with enduring and clinically meaningful benefits for diabetes self-management and glycaemic control in adults with type 2 diabetes and comorbid depression.

Testosterone replacement therapy may improve glucose tolerance and insulin sensitivity in diabetic hypogonadal men. The mechanisms by which testosterone decreases insulin resistance is under study. Moreover, testosterone may have a protective effect on pancreatic beta cells, which is possibly exerted by androgen-receptor-mediated mechanisms and influence of inflammatory cytokines.

Recently it has been suggested that a type of gastric bypass surgery may normalize blood glucose levels in 80–100% of severely obese patients with diabetes. The precise causal mechanisms are being intensively researched; its results may not simply be attributable to weight loss, as the improvement in blood sugars seems to precede any change in body mass. This approach may become a treatment for some people with type 2 diabetes, but has not yet been studied in prospective clinical trials. This surgery may have the additional benefit of reducing the death rate from all causes by up to 40% in severely obese people. A small number of normal to moderately obese patients with type 2 diabetes have successfully undergone similar operations.

MODY is a rare genetic form of diabetes, often mistaken for Type 1 or Type 2. The medical management is variable and depends on each individual case.

Saturday, October 26, 2019

Adrenaline

From Wikipedia, the free encyclopedia
 
Epinephrine
Skeletal formula of adrenaline
Ball-and-stick model of epinephrine (adrenaline) molecule
Clinical data
Trade namesEpiPen, Adrenaclick, others
SynonymsEpinephrine, adrenaline, adrenalin
AHFS/Drugs.comMonograph
MedlinePlusa603002
License data
Pregnancy
category
  • US: C (Risk not ruled out)
Addiction
liability
None
Routes of
administration
IV, IM, endotracheal, IC, nasal, eye drop
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)
  • UK: POM (Prescription only)
  • US: ℞-only
Pharmacokinetic data
Metabolismadrenergic synapse (MAO and COMT)
Onset of actionRapid
Elimination half-life2 minutes
Duration of actionFew minutes
ExcretionUrine
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
PDB ligand
CompTox Dashboard (EPA)
ECHA InfoCard100.000.090 Edit this at Wikidata
Chemical and physical data
FormulaC9H13NO3
Molar mass183.204 g/mol g·mol−1
3D model (JSmol)
Density1.283±0.06 g/cm3 @ 20 °C, 760 Torr

Adrenaline, also known as epinephrine, is a hormone and medication. Adrenaline is normally produced by both the adrenal glands and a small number of neurons in the medulla oblongata where it acts as a neurotransmitter involved in regulating visceral functions (e.g., respiration). It plays an important role in the fight-or-flight response by increasing blood flow to muscles, output of the heart, pupil dilation response, and blood sugar level. It does this by binding to alpha and beta receptors. It is found in many animals and some single cell organisms. Napoleon Cybulski first isolated epinephrine in 1895.

Medical uses

As a medication, it is used to treat a number of conditions including anaphylaxis, cardiac arrest, and superficial bleeding. Inhaled adrenaline may be used to improve the symptoms of croup. It may also be used for asthma when other treatments are not effective. It is given intravenously, by injection into a muscle, by inhalation, or by injection just under the skin. Common side effects include shakiness, anxiety, and sweating. A fast heart rate and high blood pressure may occur. Occasionally it may result in an abnormal heart rhythm. While the safety of its use during pregnancy and breastfeeding is unclear, the benefits to the mother must be taken into account.

A case has been made for the use of adrenaline infusion in place of the widely accepted treatment of inotopes for preterm infants with clinical cardiovascular compromise. Although there is sufficient data which strongly recommends Adrenaline infusions as a viable treatment, more trials are needed in order to conclusively determine that these infusions will successfully reduce morbidity and mortality rates among preterm, cardiovascularly compromised infants.

Physiological effects

The adrenal medulla is a minor contributor to total circulating catecholamines (L-DOPA is at a higher concentration in the plasma), though it contributes over 90% of circulating adrenaline. Little adrenaline is found in other tissues, mostly in scattered chromaffin cells. Following adrenalectomy, adrenaline disappears below the detection limit in the blood stream.

The adrenal glands contribute about 7% of circulating noradrenaline, most of which is a spill over from neurotransmission with little activity as a hormone. Pharmacological doses of adrenaline stimulate α1, α2, β1, β2, and β3 adrenoceptors of the sympathetic nervous system. Sympathetic nerve receptors are classified as adrenergic, based on their responsiveness to adrenaline.

The term "adrenergic" is often misinterpreted in that the main sympathetic neurotransmitter is noradrenaline, rather than adrenaline, as discovered by Ulf von Euler in 1946.

Adrenaline does have a β2 adrenoceptor-mediated effect on metabolism and the airway, there being no direct neural connection from the sympathetic ganglia to the airway.

The concept of the adrenal medulla and the sympathetic nervous system being involved in the flight, fight and fright response was originally proposed by Cannon. But the adrenal medulla, in contrast to the adrenal cortex, is not required for survival. In adrenalectomized patients hemodynamic and metabolic responses to stimuli such as hypoglycemia and exercise remain normal.

Exercise

One physiological stimulus to adrenaline secretion is exercise. This was first demonstrated using the denervated pupil of a cat as an assay, later confirmed using a biological assay on urine samples. Biochemical methods for measuring catecholamines in plasma were published from 1950 onwards. Although much valuable work has been published using fluorimetric assays to measure total catecholamine concentrations, the method is too non-specific and insensitive to accurately determine the very small quantities of adrenaline in plasma. The development of extraction methods and enzyme-isotope derivate radio-enzymatic assays (REA) transformed the analysis down to a sensitivity of 1 pg for adrenaline. Early REA plasma assays indicated that adrenaline and total catecholamines rise late in exercise, mostly when anaerobic metabolism commences.

During exercise the adrenaline blood concentration rises partially from increased secretion from the adrenal medulla and partly from decreased metabolism because of reduced hepatic blood flow. Infusion of adrenaline to reproduce exercise circulating concentrations of adrenaline in subjects at rest has little haemodynamic effect, other than a small β2-mediated fall in diastolic blood pressure. Infusion of adrenaline well within the physiological range suppresses human airway hyper-reactivity sufficiently to antagonize the constrictor effects of inhaled histamine.

A link between what we now know as the sympathetic system and the lung was shown in 1887 when Grossman showed that stimulation of cardiac accelerator nerves reversed muscarine-induced airway constriction. In experiments in the dog, where the sympathetic chain was cut at the level of the diaphragm, Jackson showed that there was no direct sympathetic innervation to the lung, but that bronchoconstriction was reversed by release of adrenaline from the adrenal medulla. An increased incidence of asthma has not been reported for adrenalectomized patients; those with a predisposition to asthma will have some protection from airway hyper-reactivity from their corticosteroid replacement therapy. Exercise induces progressive airway dilation in normal subjects that correlates with work load and is not prevented by beta blockade. The progressive dilation of the airway with increasing exercise is mediated by a progressive reduction in resting vagal tone. Beta blockade with propranolol causes a rebound in airway resistance after exercise in normal subjects over the same time course as the bronchoconstriction seen with exercise induced asthma. The reduction in airway resistance during exercise reduces the work of breathing.

Emotional response

Every emotional response has a behavioral component, an autonomic component, and a hormonal component. The hormonal component includes the release of adrenaline, an adrenomedullary response that occurs in response to stress and that is controlled by the sympathetic nervous system. The major emotion studied in relation to adrenaline is fear. In an experiment, subjects who were injected with adrenaline expressed more negative and fewer positive facial expressions to fear films compared to a control group. These subjects also reported a more intense fear from the films and greater mean intensity of negative memories than control subjects. The findings from this study demonstrate that there are learned associations between negative feelings and levels of adrenaline. Overall, the greater amount of adrenaline is positively correlated with an arousal state of negative feelings. These findings can be an effect in part that adrenaline elicits physiological sympathetic responses including an increased heart rate and knee shaking, which can be attributed to the feeling of fear regardless of the actual level of fear elicited from the video. Although studies have found a definite relation between adrenaline and fear, other emotions have not had such results. In the same study, subjects did not express a greater amusement to an amusement film nor greater anger to an anger film. Similar findings were also supported in a study that involved rodent subjects that either were able or unable to produce adrenaline. Findings support the idea that adrenaline does have a role in facilitating the encoding of emotionally arousing events, contributing to higher levels of arousal due to fear.

Memory

It has been found that adrenergic hormones, such as adrenaline, can produce retrograde enhancement of long-term memory in humans. The release of adrenaline due to emotionally stressful events, which is endogenous adrenaline, can modulate memory consolidation of the events, ensuring memory strength that is proportional to memory importance. Post-learning adrenaline activity also interacts with the degree of arousal associated with the initial coding. There is evidence that suggests adrenaline does have a role in long-term stress adaptation and emotional memory encoding specifically. Adrenaline may also play a role in elevating arousal and fear memory under particular pathological conditions including post-traumatic stress disorder. Overall, "Extensive evidence indicates that epinephrine (EPI) modulates memory consolidation for emotionally arousing tasks in animals and human subjects.” Studies have also found that recognition memory involving adrenaline depends on a mechanism that depends on β adrenoceptors. Adrenaline does not readily cross the blood–brain barrier, so its effects on memory consolidation are at least partly initiated by β adrenoceptors in the periphery. Studies have found that sotalol, a β adrenoceptor antagonist that also does not readily enter the brain, blocks the enhancing effects of peripherally administered adrenaline on memory. These findings suggest that β adrenoceptors are necessary for adrenaline to have an effect on memory consolidation. 

For noradrenaline to be acted upon by PNMT in the cytosol, it must first be shipped out of granules of the chromaffin cells. This may occur via the catecholamine-H+ exchanger VMAT1. VMAT1 is also responsible for transporting newly synthesized adrenaline from the cytosol back into chromaffin granules in preparation for release.

In liver cells, adrenaline binds to the β adrenergic receptor, which changes conformation and helps Gs, a G protein, exchange GDP to GTP. This trimeric G protein dissociates to Gs alpha and Gs beta/gamma subunits. Gs alpha binds to adenyl cyclase, thus converting ATP into cyclic AMP. Cyclic AMP binds to the regulatory subunit of protein kinase A: Protein kinase A phosphorylates phosphorylase kinase. Meanwhile, Gs beta/gamma binds to the calcium channel and allows calcium ions to enter the cytoplasm. Calcium ions bind to calmodulin proteins, a protein present in all eukaryotic cells, which then binds to phosphorylase kinase and finishes its activation. Phosphorylase kinase phosphorylates glycogen phosphorylase, which then phosphorylates glycogen and converts it to glucose-6-phosphate.

Pathology

Increased adrenaline secretion is observed in pheochromocytoma, hypoglycemia, myocardial infarction and to a lesser degree in benign essential familial tremor. A general increase in sympathetic neural activity is usually accompanied by increased adrenaline secretion, but there is selectivity during hypoxia and hypoglycaemia, when the ratio of adrenaline to noradrenaline is considerably increased. Therefore, there must be some autonomy of the adrenal medulla from the rest of the sympathetic system.

Myocardial infarction is associated with high levels of circulating adrenaline and noradrenaline, particularly in cardiogenic shock.

Benign familial tremor (BFT) is responsive to peripheral β adrenergic blockers and β2-stimulation is known to cause tremor. Patients with BFT were found to have increased plasma adrenaline, but not noradrenaline.

Low, or absent, concentrations of adrenaline can be seen in autonomic neuropathy or following adrenalectomy. Failure of the adrenal cortex, as with Addisons disease, can suppress adrenaline secretion as the activity of the synthesing enzyme, phenylethanolamine-N-methyltransferase, depends on the high concentration of cortisol that drains from the cortex to the medulla.

Terminology

In 1901, Jōkichi Takamine patented a purified extract from the adrenal glands, and called it "adrenalin" (from the Latin ad and renal, "near the kidneys"), which was trademarked by Parke, Davis & Co in the US. The British Approved Name and European Pharmacopoeia term for this drug is hence adrenaline

However, the pharmacologist John Abel had already prepared an extract from adrenal glands as early as 1897, and coined the name epinephrine to describe it (from the Greek epi and nephros, "on top of the kidneys"). In the belief that Abel's extract was the same as Takamine's (a belief since disputed), epinephrine became the generic name in the US, and remains the pharmaceutical's United States Adopted Name and International Nonproprietary Name (though the name adrenaline is frequently used). 

The terminology is now one of the few differences between the INN and BAN systems of names. Although European health professionals and scientists preferentially use the term adrenaline, the converse is true among American health professionals and scientists. Nevertheless, even among the latter, receptors for this substance are called adrenergic receptors or adrenoceptors, and pharmaceuticals that mimic its effects are often called adrenergics. The history of adrenaline and epinephrine is reviewed by Rao [Trends in Endocrinology and Metabolism, 30(6): 331-334, 2019].

Mechanism of action

Physiologic responses to adrenaline by organ
Organ Effects
Heart Increases heart rate; contractility; conduction across AV node
Lungs Increases respiratory rate; bronchodilation
Liver Stimulates glycogenolysis
Brain
Systemic Vasoconstriction and vasodilation
Triggers lipolysis
Muscle contraction

As a hormone, adrenaline acts on nearly all body tissues. Its actions vary by tissue type and tissue expression of adrenergic receptors. For example, high levels of adrenaline causes smooth muscle relaxation in the airways but causes contraction of the smooth muscle that lines most arterioles.

Adrenaline acts by binding to a variety of adrenergic receptors. Adrenaline is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3. Adrenaline's binding to these receptors triggers a number of metabolic changes. Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis and inhibits insulin-mediated glycogenesis in muscle. β adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Together, these effects lead to increased blood glucose and fatty acids, providing substrates for energy production within cells throughout the body.

Its actions are to increase peripheral resistance via α1 receptor-dependent vasoconstriction and to increase cardiac output via its binding to β1 receptors. The goal of reducing peripheral circulation is to increase coronary and cerebral perfusion pressures and therefore increase oxygen exchange at the cellular level. While adrenaline does increase aortic, cerebral, and carotid circulation pressure, it lowers carotid blood flow and end-tidal CO2 or ETCO2 levels. It appears that adrenaline may be improving macrocirculation at the expense of the capillary beds where actual perfusion is taking place.

Measurement in biological fluids

Adrenaline may be quantified in blood, plasma or serum as a diagnostic aid, to monitor therapeutic administration, or to identify the causative agent in a potential poisoning victim. Endogenous plasma adrenaline concentrations in resting adults are normally less than 10 ng/L, but may increase by 10-fold during exercise and by 50-fold or more during times of stress. Pheochromocytoma patients often have plasma adrenaline levels of 1000–10,000 ng/L. Parenteral administration of adrenaline to acute-care cardiac patients can produce plasma concentrations of 10,000 to 100,000 ng/L.

Biosynthesis and regulation

The biosynthesis of adrenaline involves a series of enzymatic reactions.
 
In chemical terms, adrenaline is one of a group of monoamines called the catecholamines. Adrenaline is synthesized in the chromaffin cells of the adrenal medulla of the adrenal gland and a small number of neurons in the medulla oblongata in the brain through a metabolic pathway that converts the amino acids phenylalanine and tyrosine into a series of metabolic intermediates and, ultimately, adrenaline. Tyrosine is first oxidized to L-DOPA by Tyrosine hydroxylase, this is the rate-limiting step. Then it is subsequently decarboxylated to give dopamine by DOPA decarboxylase (aromatic L-amino acid decarboxylase). Dopamine is then converted to noradrenaline by dopamine beta-hydroxylase which utilizes ascorbic acid (Vitamin C) and copper. The final step in adrenaline biosynthesis is the methylation of the primary amine of noradrenaline. This reaction is catalyzed by the enzyme phenylethanolamine N-methyltransferase (PNMT) which utilizes S-adenosyl methionine (SAMe) as the methyl donor. While PNMT is found primarily in the cytosol of the endocrine cells of the adrenal medulla (also known as chromaffin cells), it has been detected at low levels in both the heart and brain.

Regulation

The major physiologic triggers of adrenaline release center upon stresses, such as physical threat, excitement, noise, bright lights, and high or low ambient temperature. All of these stimuli are processed in the central nervous system.

Adrenocorticotropic hormone (ACTH) and the sympathetic nervous system stimulate the synthesis of adrenaline precursors by enhancing the activity of tyrosine hydroxylase and dopamine β-hydroxylase, two key enzymes involved in catecholamine synthesis. ACTH also stimulates the adrenal cortex to release cortisol, which increases the expression of PNMT in chromaffin cells, enhancing adrenaline synthesis. This is most often done in response to stress. The sympathetic nervous system, acting via splanchnic nerves to the adrenal medulla, stimulates the release of adrenaline. Acetylcholine released by preganglionic sympathetic fibers of these nerves acts on nicotinic acetylcholine receptors, causing cell depolarization and an influx of calcium through voltage-gated calcium channels. Calcium triggers the exocytosis of chromaffin granules and, thus, the release of adrenaline (and noradrenaline) into the bloodstream.

Unlike many other hormones adrenaline (as with other catecholamines) does not exert negative feedback to down-regulate its own synthesis. Abnormally elevated levels of adrenaline can occur in a variety of conditions, such as surreptitious adrenaline administration, pheochromocytoma, and other tumors of the sympathetic ganglia.

Its action is terminated with reuptake into nerve terminal endings, some minute dilution, and metabolism by monoamine oxidase and catechol-O-methyl transferase.

History

Extracts of the adrenal gland were first obtained by Polish physiologist Napoleon Cybulski in 1895. These extracts, which he called nadnerczyna ("adrenalin"), contained adrenaline and other catecholamines. American ophthalmologist William H. Bates discovered adrenaline's usage for eye surgeries prior to 20 April 1896. Japanese chemist Jōkichi Takamine and his assistant Keizo Uenaka independently discovered adrenaline in 1900. In 1901, Takamine successfully isolated and purified the hormone from the adrenal glands of sheep and oxen. Adrenaline was first synthesized in the laboratory by Friedrich Stolz and Henry Drysdale Dakin, independently, in 1904.

Society and culture

Adrenaline junkie

An adrenaline junkie is somebody who engages in sensation-seeking behavior through "the pursuit of novel and intense experiences without regard for physical, social, legal or financial risk". Such activities include extreme and risky sports, substance abuse, unsafe sex, and crime. The term relates to the increase in circulating levels of adrenaline during physiological stress. Such an increase in the circulating concentration of adrenaline is secondary to activation of the sympathetic nerves innervating the adrenal medulla, as it is rapid and not present in animals where the adrenal gland has been removed. Although such stress triggers adrenaline release, it also activates many other responses within the central nervous system reward system which drives behavioral responses, so while the circulating adrenaline concentration is present, it may not drive behavior. Nevertheless, adrenaline infusion alone does increase alertness and has roles in the brain including the augmentation of memory consolidation.

Strength

Adrenaline has been implicated in feats of great strength, often occurring in times of crisis. For example, there are stories of a parent lifting part of a car when their child is trapped underneath.

Entropy (information theory)

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