Growth Hormones - What are Growth Hormones?

Growth Hormones 

Growth hormone (GH) is a protein-based peptide hormone. It stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland.

Somatotropin refers to the growth hormone 1 produced naturally in animals, whereas the term somatropin refers to growth hormone produced by recombinant DNAtechnology, and is abbreviated "HGH" in humans.

Growth hormone is used in medicine to treat children's growth disorders and adult growth hormone deficiency. In recent years, growth hormone replacement therapies have become popular in the battle against ageing and obesity.

Reported effects on GH-deficient patients (but not on healthy people) include decreased body fat, increased muscle mass, increased bone density, increased energy levels, improved skin tone and texture, increased sexual function, and improved immune system function. At this time, hGH is still considered a very complex hormone, and many of its functions are still unknown.

In its role as an anabolic agent, HGH has been used by competitors in sports since the 1970s, and it has been banned by the IOC and NCAA.

Traditional urine analysis could not detect doping with HGH, so the ban was unenforceable until the early 2000s when blood tests that could distinguish between natural and artificial hGH were starting to be developed.

Blood tests conducted by WADA at the 2004 Olympic Games in Athens primarily targeted HGH. while recently an additional variant of ~ 23-24 kDa has also been reported in post-exercise states at higher proportions.

This variant has not been identified, but it has been suggested to coincide with a 22 kDa glycosilated variant of 23 kDa identified in the pituitary gland.

Furthermore, these variants circulate partially bound to a protein (growth hormone-binding protein, GHBP), which is the truncated part of the growth hormone receptor, and an acid-labile subunit (ALS).

Regulation

Peptides released by neurosecretory nuclei of the hypothalamus (Growth hormone-releasing hormone/''somatocrinin'' and Growth hormone-inhibiting hormone/''somatostatin'') into the hypophyseal portal venous blood surrounding the pituitary are the major controllers of GH secretion by the somatotropes.

However, although the balance of these stimulating and inhibiting peptides determines GH release, this balance is affected by many physiological stimulators (e.g., exercise, nutrition, sleep) and inhibitors of GH secretion (e.g., Free fatty acids)

''Stimulators'' of HGH secretion include:

• peptide hormones
  • Growth hormone-releasing hormone (GHRH) through binding to the growth hormone-releasing hormone receptor (GHRHR)
  • ghrelin through binding to growth hormone secretagogue receptors (GHSR)
  • sex hormones
    • increased androgen secretion during puberty (in males from testis and in females from adrenal cortex)
    • estrogen
    • clonidine and L-DOPA by stimulating GHRH release
    • hypoglycemia, arginine and propranolol by inhibiting somatostatin release
    • fasting
    • vigorous exercise

''Inhibitors'' of GH secretion include:

• somatostatin from the periventricular nucleus
• circulating concentrations of GH and IGF-1 (negative feedback on the pituitary and hypothalamus)
• dihydrotestosterone

In addition to control by endogenous and stimulus processes, a number of foreign compounds (xenobiotics such as drugs and endocrine disruptors) are known to influence GH secretion and function.

Secretion patterns

HGH is synthesized and secreted from the anterior pituitary gland in a pulsatile manner throughout the day; surges of secretion occur at 3- to 5-hour intervals. The largest and most predictable of these GH peaks occurs about an hour after onset of sleep. Otherwise there is wide variation between days and individuals.

Nearly fifty percent of HGH secretion occurs during the third and fourth REM sleep stages. Between the peaks, basal GH levels are low, usually less than 5 ng/mL for most of the day and night.

A number of factors are known to affect HGH secretion, such as age, gender, diet, exercise, stress, and other hormones.

Prostate Cancer

Prostate Cancer Overview

What is prostate cancer? Prostate cancer occurs when cells in the prostate gland grow out of control. There are often no early prostate cancer symptoms, but some men have urinary symptoms and discomfort. Prostate cancer treatment options are surgery, chemotherapy, cryotherapy, hormonal therapy, and/or radiation. In some instances, doctors recommend "watchful waiting."

What Are the Symptoms of Prostate Cancer?

There are no warning signs or symptoms of early prostate cancer. Once a malignant tumor causes the prostate gland to swell significantly, or once cancer spreads beyond the prostate, the following symptoms may be present:

• A frequent need to urinate, especially at night
• Difficulty starting or stopping a stream of urine
• A weak or interrupted urinary stream
• Leaking of urine when laughing or coughing
• Inability to urinate standing up
• A painful or burning sensation during urination or ejaculation
• Blood in urine or semen

Proton Beam Therapy Better for Prostate Cancer?

Nov. 1, 2012 (Boston) -- A pricey new treatment for prostate cancer called proton beam therapy appears to cause slightly less diarrhea, bloating, and cramping than traditional radiation treatments. But the effect is short-lived, a new study suggests.

The findings come from a review of questionnaires filled out by men who underwent one of three forms of radiation therapy, so the results are far from conclusive.

But even though proton beam therapy's effectiveness and safety has yet to be proven, more and more men are opting for the treatment. The number of treatments has climbed steadily in the last five years and is expected to double in the next three years, says researcher Phillip J. Gray, MD, a resident in the Harvard Radiation Oncology program in Boston.

"Patients say proton beam therapy sounds so much better, they want it no matter what the cost," says Colleen Lawton, MD, a radiation oncologist at the Medical College of Wisconsin Clinical Cancer Center in Milwaukee.

"We don't know if it is less toxic. We don’t know if it is more effective. All we do know is that it is more costly."

Lawton, who was not involved with the research, moderated a news briefing to discuss the findings here at the annual meeting of the American Society for Radiation Oncology (ASTRO).

Bowel, Urinary Problems

In proton beam therapy, beams of protons are targeted directly to tumors, thereby sparing healthy tissue, which theoretically should cause fewer side effects. Indeed, its benefit in treating eye and pediatric brain tumors is well documented. But for prostate cancer, the answer is far less clear.

So Gray and colleagues studied three groups of men: 94 who got proton beam therapy, 153 who were treated with what's called intensity-modulated radiation therapy (IMRT), and 123 who were treated with an older form of external beam radiation that IMRT has replaced over the past decade.

Internal radiation therapy (also known as brachytherapy) was not included in this study.

IMRT also delivers its radiation with extremely high precision, thereby reducing the risk that it will hit surrounding healthy tissue -- but in this case the cargo is X-ray radiation, not protons.

By two to three months later, men treated with proton beam therapy reported minimal diarrhea and cramping compared with men in either of the other two groups.

But by one year later, men treated with proton beams had similar bowel problems, and that persisted out to the two years of the study.

All three groups had more urinary irritation and flow problems in the first few months of treatment than they did before the study started. Men given IMRT fared the worst, reporting bothersome urinary problems in the early months. "By two years out, all three groups had minimal, lingering problems," Gray says.

And all three groups reported worsening sexual function over the two years of the study.

The men weren't followed for long enough to know whether one treatment curbs tumor growth better than the others.

Alzheimer's disease: 10 Warning Signs

Alzheimer's disease is a progressive, degenerative disease. Symptoms include loss of memory, difficulty with day-to-day tasks, and changes in mood and behaviour. People may think these symptoms are part of normal aging but they aren't. It is important to see a doctor when you notice any of these symptoms as they may be due to other conditions such as depression, drug interactions or an infection. If the diagnosis is Alzheimer's disease, your local Alzheimer Society can help.
To help you know what warning signs to look for, the Alzheimer Society has developed the following list:

1. Memory loss that affects day-to-day function
   It's normal to occasionally forget appointments, colleagues' names or a friend's phone number and remember them later. A person with Alzheimer's disease may forget things more often and not remember them later, especially things that have happened more recently.
2. Difficulty performing familiar tasks
   Busy people can be so distracted from time to time that they may leave the carrots on the stove and only remember to serve them at the end of a meal. A person with Alzheimer's disease may have trouble with tasks that have been familiar to them all their lives, such as preparing a meal.
3. Problems with language
   Everyone has trouble finding the right word sometimes, but a person with Alzheimer's disease may forget simple words or substitute words, making her sentences difficult to understand.
4. Disorientation of time and place
   It's normal to forget the day of the week or your destination -- for a moment. But a person with Alzheimer's disease can become lost on their own street, not knowing how they got there or how to get home.
5. Poor or decreased judgment
   People may sometimes put off going to a doctor if they have an infection, but eventually seek medical attention. A person with Alzheimer's disease may have decreased judgment, for example not recognizing a medical problem that needs attention or wearing heavy clothing on a hot day.
6. Problems with abstract thinking
   From time to time, people may have difficulty with tasks that require abstract thinking, such as balancing a cheque book. Someone with Alzheimer's disease may have significant difficulties with such tasks, for example not recognizing what the numbers in the cheque book mean.
7. Misplacing things
   Anyone can temporarily misplace a wallet or keys. A person with Alzheimer's disease may put things in inappropriate places: an iron in the freezer or a wristwatch in the sugar bowl.
8. Changes in mood and behaviour
   Everyone becomes sad or moody from time to time. Someone with Alzheimer's disease can exhibit varied mood swings -- from calm to tears to anger -- for no apparent reason.
9. Changes in personality
   People's personalities can change somewhat with age. But a person with Alzheimer's disease can become confused, suspicious or withdrawn. Changes may also include apathy, fearfulness or acting out of character.
10. Loss of initiative
    It's normal to tire of housework, business activities or social obligations, but most people regain their initiative. A person with Alzheimer's disease may become very passive, and require cues and prompting to become involved.