Eyeing the world of food, nutrition, and medicine through the lens of evidence and evolution.
03 May 2009
Getting high off endorphins
What the heck are these endorphins anyway? Well, they are your body’s own natural painkillers (1) and they are distributed throughout the brain stem binding to receptors. The drug, morphine, attaches to the same receptors to dull pain (1). The name endorphin, in fact, comes from “endogenous morphinelike substance” (1).
So, what about exercise? Anything to it? Yes. I was able to find in quite a few studies that exercise, almost any kind, does increase endorphin levels in the blood (2-7). In fact, a study in 1995 showed that when compared to meditation, running was more effective for releasing endorphins (7).To get the most potent pain-killing buzz from your workout, do high-intensity exercise to reach your anaerobic threshold. Anaerobic exercise promotes greater endorphin release than aerobic exercise (2). (Although the workout might come back to haunt you with pain later.) It was thought that lactic acid played a role in causing endorphin release, but this theory has been challenged (8).
Also, you don’t have to exercise for natural pain relief. There are other ways. Exposure to cold appears to stimulate endorphin release and a huge amount of electrical impulses to the brain (9). This led to one hypothesis that taking a cold shower daily may be useful to help those with depression (9). Electroacupuncture can help stimulate endorphin release, which may explain why it may be a good complementary treatment for pain (10).Massage therapy is also thought to stimulate endorphin release, but its effects are not proven (2).
It’s worth noting that in patients with heart failure, a functional disability includes decreased release of endorphins during exercise (11).
Reference List
1. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
2. Bender T, Nagy G, Barna I, Tefner I, Kadas E, Geher P. The effect of physical therapy on beta-endorphin levels. Eur J Appl Physiol 2007;100:371-82.
3. Armstrong DW, III, Hatfield BD. Hormonal responses to opioid receptor blockade: during rest and exercise in cold and hot environments. Eur J Appl Physiol 2006;97:43-51.
4. Harbach H, Hell K, Gramsch C, Katz N, Hempelmann G, Teschemacher H. Beta-endorphin (1-31) in the plasma of male volunteers undergoing physical exercise. Psychoneuroendocrinology 2000;25:551-62.
5. Jarmukli NF, Ahn J, Iranmanesh A, Russell DC. Effect of raised plasma beta endorphin concentrations on peripheral pain and angina thresholds in patients with stable angina. Heart 1999;82:204-9.
6. Goldfarb AH, Jamurtas AZ. Beta-endorphin response to exercise. An update. Sports Med 1997;24:8-16.
7. Harte JL, Eifert GH, Smith R. The effects of running and meditation on beta-endorphin, corticotropin-releasing hormone and cortisol in plasma, and on mood. Biol Psychol 1995;40:251-65.
8. Petrides JS, Deuster PA, Mueller GP. Lactic acid does not directly activate hypothalamic-pituitary corticotroph function. Proc Soc Exp Biol Med 1999;220:100-5.
9. Shevchuk NA. Adapted cold shower as a potential treatment for depression. Med Hypotheses 2008;70:995-1001.
10. Lee SH, Lee BC. Electroacupuncture relieves pain in men with chronic prostatitis/chronic pelvic pain syndrome: three-arm randomized trial. Urology 2009;73:1036-41.
11. Perna GP, Modoni S, Valle G, Stanislao M, Loperfido F. Plasma beta-endorphin response to exercise in patients with congestive heart failure. Chest 1997;111:19-22.
Alternative treatment for Parkinson's
Many reasons, apparently. The botanical with natural L-DOPA appears to actually help restore endogenous levels of endogenous levodopa, dopamine, norepinephrine and serotonin in the substantia nigra (1). And, unlike synthetic levodapa, it doesn’t produce DNA damage (2). The neuroprotective effects are thought to come from copper-chelation properties (2). One clinical trial on 60 patients with Parkinson’s disease taking Mucuna pruriens reported that adverse effects were limited to only gastrointestinal issues, not lab reports (3).
Reference List
1. Manyam BV, Dhanasekaran M, Hare TA. Neuroprotective effects of the antiparkinson drug Mucuna pruriens. Phytother Res 2004;18:706-12.
2. Tharakan B, Dhanasekaran M, Mize-Berge J, Manyam BV. Anti-Parkinson botanical Mucuna pruriens prevents levodopa induced plasmid and genomic DNA damage. Phytother Res 2007;21:1124-6.
3. An alternative medicine treatment for Parkinson's disease: results of a multicenter clinical trial. HP-200 in Parkinson's Disease Study Group. J Altern Complement Med 1995;1:249-55.
It's finals week and you've got a tension headache
Get headaches way too often? You might as well take poison. No, seriously! The same neurotoxic dinoflagellate contaminant that produces shellfish poisoning, and even botulinum toxin, could be injected to impede nerve impulse causing headache pain to provide significant relief (2-4).
Reference List
1. Xue CC, Dong L, Polus B et al. Electroacupuncture for tension-type headache on distal acupoints only: a randomized, controlled, crossover trial. Headache 2004;44:333-41.
2. Lattes K, Venegas P, Lagos N et al. Local infiltration of gonyautoxin is safe and effective in treatment of chronic tension-type headache. Neurol Res 2009;31:228-33.
3. de Ru JA, Buwalda J. Botulinum toxin A injection into corrugator muscle for frontally localised chronic daily headache or chronic tension-type headache. J Laryngol Otol 2009;123:412-7.
4. Freund BJ, Schwartz M. Relief of tension-type headache symptoms in subjects with temporomandibular disorders treated with botulinum toxin-A. Headache 2002;42:1033-7.
26 April 2009
Biochem of starvation
Humans didn’t always have restaurants and grocery stores to visit on every corner. As part of human evolution, in fact, most of the time it’s likely our ancestors were starving quite often and got pretty good at it while foraging and hunting.
It took the agricultural revolution to really make a shift to food aplenty. But starvation hasn’t gone away by any stretch. It’s a daily reality for much of the underdeveloped world.
And, a bit closer to my reality, my own great grandmother often shared stories with me about how she’d go for weeks without meals as a little girl.
To be able to survive from meal to meal, we depend on a starve-feed cycle. It refers to the changes in metabolism that allows variable fuel and nitrogen consumption to meet variable metabolic and anabolic demand (1). In plain English, it is what gives humans capacity to eat food well beyond caloric requirements and store it as glycogen and triacylglycerol to utilize when needed (1).
This is what happens to someone biochemically as they enter starvation.
Early Starvation State (about two-five days after last meal)
About two days after a last meal with insulin low and glycagon on the rise, glycogen is depleted and muscle proteolysis is predominating (1). The protein catabolism would release of a mix of amino acids high in alanine and glutamine into the blood (1p246).
The alanine stimulates glycogen and is taken up from the liver where it's deaminated for conversion to urea and where pyruvate can be used for gluconeogenesis (1p246). Gluconeogenesis is also made from recycled lactate, pyruvate and from glycerol from fat tissue lipolysis (1p245). Blood glucose levels are successfully kept normal (1p246).
Prolonged Starvation State (one week or longer after last meal)
As starvation becomes prolonged, the body enters a metabolic shift. The shift is away from the glycogen-depleting and muscle-protein-breakdown fasting state (1). The body now intends to conserve vital body proteins to preserve vital functions such as antibodies fighting infection, enzymes catalyzing reactions and hemoglobin transporting oxygen (1).
For energy, the body begins using fat conveniently stored in adipose tissue during a time when more calories were consumed than expended (1). Thus, the blood’s level of fatty acids increases as those fatty acids become fuel (1). The heart, liver and muscle all oxidize them, but not the brain because fatty acids can’t cross the blood-brain barrier (1). The brain can use glycerol backbones, however, and these largely replace amino acids and glucose as its fuel (1).
TCA cycle intermediates for gluconeogenesis eventually become depleted and low levels of oxaloacetate coupled with rapid production of acetyl CoA from fatty acid catabolism create accumulation favoring ketone bodies (1). The ketone bodies are valuable as an energy source for sparing protein (1).
To survive in a starvation state generally depends on stored fat before starvation, although ketosis can cause significant physiological damage and even death (1). The ketosis is kept in check as long as possible by directing glutamine to kidneys, but acidosis increases as ketone production accelerates (1). Once fat stores are used up the body starts on essential protein leading to liver and muscle function loss that ultimately leads to death (1).
Reintroducing Food
As a starved person begins to eat again, there are metabolic interrelationships between the liver, muscle and fat tissue. Triaylglycerol is metabolized normally, but glucose metabolism must be slowly re-established (1). The reason is because the liver extracts glucose poorly and ends up staying in a gluconeogenec mode for awhile after feeding (1).
But the hepatic gluconeogenesis is not producing blood glucose (1). It's providing glucose 6-phosphate for glycogenesis (1). It's an indirect pathway for glycogen synthesis because glucose is catabolized in other tissues (muscle, fat) and then sent to the liver to be converted to the glycogen (1).
Finally, after a few hours, gluconeogenesis declines and glycolysis predominates (1). The liver glycogen then can be sustained again by direct synthesis from blood glucose (1).
Reference List
1. Devlin TM. Textbook of Biochemistry with Clinical Correlations. Philadelphia: Wiley-Liss, 2002.
2. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
Other:
Johnstone AM. Fasting - the ultimate diet? Obes Rev 2007;8:211-22.
Cahill GF, Jr. Fuel metabolism in starvation. Annu Rev Nutr 2006;26:1-22.
How does fat get absorbed and stored as fat?
Reference
1. Devlin TM. Textbook of Biochemistry with Clinical Correlations. Philadelphia: Wiley-Liss, 2002.
19 April 2009
Levels of consciousness (and no, I'm not Deepak Chopra)
Example of consciousness terminology (1):
- Normal consciousness is characterized by a fully responsive, self-awareness and awareness of surroundings
- Inattention is when a patient finds it difficult to identify and attend revelant stimuli
- Confusion happens when thinking is slower or less clear; or when a patient is distracted
- Clouding (obtundation) is when inattention and confusion are more profound; rousing is more difficult
- Stupor is physical and mental activity at its minimum (kind of like me in the morning); you have to use persistent and vigorous stimulation to arouse them
- Coma is when a patient simply can’t be aroused, but might produce a pattern of behavior if stimulus is intense
Many clinical methods of have been used to determine the conscious state. The Glasgow Coma Scale, introduced in 1974 (2), has been functional in many hospitals including Grady Memorial Hospital in Atlanta, Georgia, for 30 years (3). The scale is easy to use using eye, verbal and motor responses (1;3). But it does have many limitations because there is a tendency to skew scores depending on experience of examiners and their paradigms (2). New techniques for determining consciousness may come in the future. They may include new terminology and new scales (2;3).
Reference List
1. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
2. Matis G, Birbilis T. The Glasgow Coma Scale--a brief review. Past, present, future. Acta Neurol Belg 2008;108:75-89.
3. Tindall S. 1990. Levels of Consciousness. Clinical Methods: The History, Physical, and Laboratory Examinations. Available at: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cm&part=A1731
Don't depend on Glasgow Coma Scale
But it should be clear that it should not be the only test used. This was a hard lesson for the medics that treated Natasha Richardson after her skiing head injury (2). For this reason when my daughter fell off a scooter and hurt her head, her doctor suggested I take her to the hospital for a scan.
Reference
1. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
2. Tremblant M. 2009. 911 Calls Show Urgency of Richardson Fall. CBS News. Available at: http://www.cbsnews.com/stories/2009/03/31/entertainment/main4906004.shtml
Neural tube defects may not be related to high sugar intake
Reference List
1. Shaw GM, Carmichael SL, Laurent C, Siega-Riz AM. Periconceptional glycaemic load and intake of sugars and their association with neural tube defects in offspring. Paediatr Perinat Epidemiol 2008;22:514-9.
18 April 2009
Going senile
Dementia is a symptom used in a broad way to describe any loss of ordered neural function. It affects my grandfather as senility—its cause being his age of 82. It is a relief that my grandmother, just as old, does not show similar signs. And I just hope my parents don’t get it. I hope I don’t get it. Worst case scenario would be Alzheimer’s disease—the slow progression of dementia to the point that mental function is surrendered. If you happen to live with a parent or grandparent who is one of the 6 percent of the population that has Alzheimer’s, then, yes, I feel for you. My situation doesn’t come close.
Depending on the pathological cause, dementia can be reversible. If altered mental function is due to depression, impaired heart function, or anemia, it can be helped. We know now that Pick’s and Alzheimer’s disease are different because they affect the cerebral cortex.
Although symptoms may be indistinguishable to Alzheimer’s, Pick’s causes atrophy of the gyri, which at autopsy is called “walnut brain.” Alzheimer’s doesn’t just affect the cerebral cortex. It also affects the hippocampus, the amygdale and the basal nucleus of Meynert. This is because of widespread depletion of acetylcholine (and other chemicals) resulting from loss of cells in the nucleus of Meynert. Neurons called pyramidal cells die, their associated axons die and the brain loses its white matter. The gyri shrinks and ventricals expand worsening the atrophy.
The severity and progression of Alzheimer’s depends on three findings: 1) neurofibrillary tangles that encircle or displace the nucleus of pyramidal cells; 2) neuritic plaques that contain a cluster of neural processes filled with filaments; 3) amyloid precursor protein, which is normal in cells, but is elevated in the brains of patients with Alzheimer’s. Ten percent of cases are familial due to a gene that produces amyloid protein, which may be related to Down syndrome. Most of those with Down syndrome do develop Alzheimer’s if they live beyond 45. A mutation of another gene called APP may be related to early-onset Alzheimer’s. And research also has identified enzyme (secretases) abnormalities that may result in increased conversion of abnormal APP to amyloid beta protein.
No, there are no practical treatments for Alzheimer’s, unfortunately. Someday maybe we’ll have something to degrade amyloid protein. Elevated aluminum levels found in patients who’ve had Alzheimer’s raises concerns that those with a genetic predisposition shouldn’t use aluminum cookware or other products such as deodorants containing aluminum. To remove aluminum, chelating agents have been used to reverse symptoms. Another experimental treatment is tetrahydroaminoacridine to enhance memory, but may cause liver damage. Aspirin also appears to slow inflammation that is part of Alzheimer’s.Healthy diet and exercise as well as exercise of cognitive skills remain the most important ways to help slow the progression of dementia and Alzheimer’s.
Reference List
Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
MS patients can look forward to stem cell therapy
The researchers found improvement in symptoms after testing the therapy for five years on nine patients with severe MS, ages between 9 and 34 (1). The therapy has been studied for a total of 15 years (1).
Reference List
1. Fagius J, Lundgren J, Oberg G. Early highly aggressive MS successfully treated by hematopoietic stem cell transplantation. Mult Scler 2009;15:229-37.
Feel down in the dumps? Could be Alzheimer’s disease
Reference List
1. Robert P, Onyike CU, Leentjens AF et al. Proposed diagnostic criteria for apathy in Alzheimer's disease and other neuropsychiatric disorders. Eur Psychiatry 2009;24:98-104.
Why insulin is key for intracellular protein synthesis
Protein synthesis is also sensitive to multiple influences including stability of mRNA, amount of rRNA, activity of ribosomes, and (most important from diet), the presence of essential and nonessential amino acids in appropriate concentration to charge the tRNA and hormone environment (1p232). When amino acids are not present or not present in sufficient quantity, amino acid oxidation increases (1p232).
Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
After my high-protein shake
Well, it turns out that I need those carbs to stimulate insulin secretion to promote tissue cell uptake and use of the amino acids (1p206)(1). For this reason, it doesn’t make too much sense to take protein with some other kind of sweetener. The insulin affects movement of amino cid transporters to the membrane and their activity while also antagonizing activation of some enzymes that oxidize amino acids—very important if you’re trying to put on muscle (1p206-207)! You don’t want glucagon to dominate, leaving you with protein degradation (1p207). At least I don’t. Insulin stimulates protein synthesis and inhibits its degradation (1p207).
My shake’s protein content happens to be made up of contain whey and casein. That’s a good thing for me because whey is considered a “fast” protein that’s quickly digested, absorbed and oxidized to get that protein synthesis I want (1p207); the casein, a “slow” protein, prolongs amino acid concentration in the plasma at a low degree to keep protein synthesis up and protein degradation by around 30 percent (1p207). It’s unclear if older people are better off with the faster proteins and if younger people are better off with the slower proteins (1p207), but I’m 30 so I take both just in case. Plus, that casein keeps me feeling full longer (personal experience).
What’s also great about my protein shake is its amino acid profile. Leucine is important for promoting protein synthesis in my liver, muscles and skin because it accelerates phases of mRNA translation (1p207); plus, it’s involved in a signaling cascade to stimulate the mRNA translation (1p207). Leucine is great for me. And the whey apparently causes a rapid absorption of that leucine along with other branched-chain amino acids isoleucine and valine (2). The other amino acids will promote protein synthesis too along with cell volume through intracellular signaling, like leucine does (1p207).
Pretty much because I’ve just eaten (and just worked out), protein synthesis is dominating in my body (1p208) and the high-protein is speeding recovery of my muscles, specifically the whey more than the casein (3;4). About 20 percent of the amino acids going into the liver end up used for protein synthesis (most of what stays in the liver) and nitrogen-containing compounds (like creatine, glutathione, carnitine, carnosine, and choline) (1p198). The other amino acids end up in the plasma (1p198). Some of the amount will be used for purine and pyrimidine bases, which mainly make up DNA and RNA.
Because 40 percent of body protein is in muscle, a lot of activity occurs there (1p223). The muscle catabolizes aspartate, asparagines, glutamate and the branched-chain amino acids to a greater extent (1p223). My muscles are especially liking the content of branched-chain amino acids from the whey (2) that are circulating (1p218). Enzymes in my muscles as well as heart, kidneys, diaphragm, adipose and other organs like the liver transaminate them to be further oxidized into energy or for reamination (1p224).
Glutamine, for example, is generated in the muscle through several pathways (1p226). One such pathway includes transamination of branched-chain amino acids combined with alpha-ketoglutarate to form branched-chain alpha-keto acid and glutamate, then an enzyme combines glutamate with ammonia to form glutamine (1p226). Glutamine synthesis is relatively higher in skeletal muscle, lungs, brain and adipose tissues (1p226).
Creatine, which contains nitrogen from amino acids arginine and glycine with methyl groups donated from methionine, is also functioning in the skeletal muscle for energy (1p226). If not used it doesn’t stay there forever, but leaves the muscle as creatinine to the kidney and is excreted in urine (1p226). I can use the excretion, in fact, as a great indicator of my existing muscle and rate of degradation (1p226).
Along with creatinine, the urine will have nitrogen from urea, amino acids, ammonia and uric acid (1p238). Feces may have amino acids and ammonia too (1p238). A calculation that shows my nitrogen balance—how much protein I consume versus how much nitrogen comes out—can help me measure whether or not my protein intake is adequate and if the quality of my protein is good (1p237). After a high-protein meal the balance may be more likely to be on the side of delivering a positive result.
Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Farnfield MM, Trenerry C, Carey KA, Cameron-Smith D. Plasma amino acid response after ingestion of different whey protein fractions. Int J Food Sci Nutr 2008;1-11.
3. Buckley JD, Thomson RL, Coates AM, Howe PR, Denichilo MO, Rowney MK. Supplementation with a whey protein hydrolysate enhances recovery of muscle force-generating capacity following eccentric exercise. J Sci Med Sport 2008.
4. Cribb PJ, Williams AD, Carey MF, Hayes A. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int J Sport Nutr Exerc Metab 2006;16:494-509.
Should I starve or should I receive bodily injury?
The answer is pretty straightforward. My body’s insulin would drop while glucagon would rise (1p246). Muscle and fat tissue would also become a bit resistant to insulin (1p246). Protein synthesis would drop (1p246). Glycogen from my liver would start becoming used up and muscles would release a mix of amino acids for gluconeogenesis (stimulating the glucagon) (1p246). The liver would keep my blood sugar level stable (1p246). If I didn’t eat for awhile, then my tissues would keep using fatty acids and glucose, but also start using ketones (from the fatty acid oxidation) for gluconeogenesis too (1p246). This is an important step to limit to conserve body protein, but does increase acidosis (1p246). The body has a way to deal with that too: more glutamine directed to the kidneys produces ammonia that combines with hydrogen ions to make urea for excretion (1p246). Acidosis is corrected and the kidney simply uses the carbon skeleton of glutamine to make glucose (1p246).
Summary of Starvation –
- Glucagon up, insulin down
- Reduced mRNA for translate of proteins
- Protein synthesis drops
- Increased starvation leads to decrease in secretion of glucocorticoids including cortisol
- Few days of fasting or starvation, glycogen is depleted and muscles undergo proteolysis for gluconeogenesis
- As fasting continues, tissues use fatty acids and glucose, but also ketones from fatty acids.
- Decrease in protein catabolism.
Apart from hurting pretty bad, stress from trauma like from a gun shot wound or burn would cause a bunch of problems. Mainly, it would send hormones in my body into a frenzy; glutocorticoids (primarily cortisol), catecholamines, cytokines, insulin and glucagon would all shoot up (1p246). Unlike starvation, the insulin presence would inhibit use of ketones for energy, thus, leaving me defenseless against muscle wasting (1p246). I’d lose more fast-twitch muscle than slow-twitch muscle (1p247). And yet, because tissues would be resistant to insulin, it would be useless in guarding against hyperglycemia caused partly by elevated cortisol (1p247). The cortisol, in fact, would be promoting the proteolysis (1p247). Cytokines would mediate proteolysis as well as hormonal response (1p247). The cytokines and glucocorticoids are thought to start synthesizing proteins including acute phase reactant and acute phase response proteins that cause fever, further hormonal changes and blood cell count changes (1p247). Other protein synthesis would decrease (1p247). To cope with possible loss of blood or to restore circulation depressed by shock, luckily, I’d have release of aldosterone and antidiuretic hormone to promote renal sodium and fluid reabsorption (1p247).
Summary of Stress –
- Glutocorticoids (primarily cortisol), catecholamines, cytokines, insulin and glucagon all up
- Tissues becomes resistant to insulin and hyperglycemia results
- Cytokines change substrate use
- Cortisol remains elevated causing proteolysis and hyperglycemia
- Cytokines and cortisol thought to increase synthesis of some proteins in liver to modulate body’s response; albumin and transferring to diminish stress
- Release of aldosterone causing sodium and fluid reabsorption and increasing blood volume (helps diminish fluid loss)
- Basal metabolic rate elevated
- Protein catabolism and lipolysis
- Lipolysis does not produce ketones for ketogenesis because of insulin presence and cannot defend against muscle catabolism
- Muscle wasting – white first, then red
- Protein turnover worsened by immune and acute phase responses (fever, etc.)
- Protein degradation exceeds starvation
Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
12 April 2009
Raw or pasteurized
But a French study in the latest J Nutr and other studies explain that when milk protein is exposed to ultra-high heat (but not pasteurization), digestibility and nutritional content due can be affected (2-4). The change occurs not specifically due to denaturation, but due to Maillard reactions (reaction between amino acids and sugars) from heat, production of unusual amino acids such as furosine, and reduced availability of essential amino acids (2-4). Pasteurization resulting in partial denaturation of milk and whey has also been shown to create a biological significance on the bioavailability of nutrients such as folic acid (5).
Still, I fear microbes, so suggest avoiding raw milk. Instead, try low-temp processed milk. Undenatured whey is good because it's filtrated, the cleaner the better for flavor.
Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Lacroix M, Bon C, Bos C et al. Ultra high temperature treatment, but not pasteurization, affects the postprandial kinetics of milk proteins in humans. J Nutr 2008;138:2342-7.
3. Corzo N, Lopez-Fandino R, Delgado T, Ramos M, Olano A. Changes in furosine and proteins of UHT-treated milks stored at high ambient temperatures. Z Lebensm Unters Forsch 1994;198:302-6.
4. Mauron J. Influence of processing on protein quality. J Nutr Sci Vitaminol (Tokyo) 1990;36 Suppl 1:S57-S69.
5. Gregory JF, III. Denaturation of the folacin-binding protein in pasteurized milk products. J Nutr 1982;112:1329-38.
Deamination and transamination
Deamination examples
The amino acid threonine has its amino group removed by threonine dehydratase (1p209). This particular amino acid is commonly deaminated along with glutamate, histidine, serine and glycine (1p209). In the case of thronine, the reaction proceeds with loss of water, which is why the enzyme catalyzing the reaction is called a dehydratase instead of a deaminase (1p209). Vitamin B6 is important for this reaction to occur (1p209). The amino group is used by periportal hepatocytes to synthesize urea (1p209).
Transamination examples
The transfer of an amino groupf from one amino acid to an amino acid carbon skeleton or alpha-keto acid occurs to feed protein synthesis (1p209). The enzymes include tyrosine aminotransferase, branched-chain aminotransferases, alanine aminotransferase, and aspartate aminotransferase (1p209). The enzymes can often require vitamin B6 in a coenzyme form (1p209). The reactions are reversible and are often used to create non-essential amino acids from essential ones except lysine, histidiene and threonine (1p209).
Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.11 April 2009
Emergency contraception and ectopic pregnancy
Reference List
1. Ghosh B, Dadhwal V, Deka D, Ramesan CK, Mittal S. Ectopic pregnancy following levonorgestrel emergency contraception: a case report. Contraception 2009;79:155-7.
Dysmenorrhea news
Endometriosis can ultimately result in causing dysmenorrhea (1). According to Chinese researchers, there has been conflicting reports leading to debate about the actual relationship, but statistical models suggest a stage and site of the endometriotic lesions (1). According to the researchers, there is still variation recognized and further research is needed (1).
Reference List
1. Liu X, Guo SW. Dysmenorrhea: risk factors in women with endometriosis. Womens Health (Lond Engl ) 2008;4:399-411.
Increased Intracranial Pressure
The potential complication can come from a variety of pathologies including central nervous system edema, tumor masses, hematoma, hydrocephalus, venous obstruction and increased CSF volume (1p557-8).
Increased ICP can occur in four stages:
- Stage 1 is a phase of potential danger from one of the complications listed previously.
- Stage 2 is a gradual rise in ICP effectively causing cerebral perfusion to drop and a decrease in oxygenation that stimulates vasoconstriction to increase cardiac output, resulting in lowered consciousness of the patient.
- Stage 3 is the established condition of rapid rise of ICP at a point where it is called the stage of decompensation and autoregulation is lost, resulting in increased blood volume in the brain, hypoxia and cytotoxic edema, which only makes things worse anc causing coma to deepen (1p558). A pattern of apnea for 15-60 seconds followed by deep, labored breathing that eventually becomes shallow and apneic again is called Cheyne-Stokes respiration (1p558). Carbon dioxide accumulation induces the cycled breathing (1p558). Hypoxia and vasoconstriction stretches pressure receptors in carotid arteries signaling the medulla to induce bradycardia (1p558).
- Stage 4 results when cerebral perfusion pressure falls below 30 mm Hg, widespread necrosis begins, and compression of brain stem respiratory centers leads to respiratory arrest and death.
Reference List
1. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
Post-32-HyperPsychoProteinuria Stages 1 and 2
The ischemic placenta also disrupts endothelia causing a predisposition to disseminated intravascular coagulation (1). This blocks microcirculation causing tissue hypoxia and reduced blood flow in the kidney causes albuminuria, which leads to systemic edema (1). The symptoms may be accompanied by headache and vision disruption (2). In addition, the woman may have memory and concentration problems, according to a study published in March (3).
Also, a March-published “revised view” in Placenta also reviews placental stress as leading to the syndrome (4). The study suggests a two-stage model claiming, “it is not only an endothelial disease, but a disorder of systemic inflammation” (4).
The syndrome was previously called toxemia, but wasn’t a good name since no toxins are involved (1). The syndrome is now called preeclampsia referring to late occurrence of convulsions and coma (1). But it could use another name more in line with its symptoms for early detection… Post-32-HyperPsychoProteinuria. And it could be separated into Stage 1 and 2.
Reference List
1. Yu L, Chen M, Zhao D et al. The H19 Gene Imprinting in Normal Pregnancy and Pre-eclampsia. Placenta 2009.
2. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
3. Baecke M, Spaanderman ME, van der Werf SP. Cognitive function after pre-eclampsia: an explorative study. J Psychosom Obstet Gynaecol 2009;30:58-64.
4. Redman CW, Sargent IL. Placental stress and pre-eclampsia: a revised view. Placenta 2009;30 Suppl A:S38-S42.