The regulation of prostaglandin E1 formation: a candidate for one of the fundamental mechanisms involved in the actions of vitamin C

Vitamin C for Type 2 Diabetes Mellitus and Hypertension

It is suggested that supplementation of vitamin C reduces hyperglycemia and lowers blood pressure in hypertensives by enhacing the formation of prostaglandin E1 (PGE1), PGI2 (prostacyclin), endothelial nitric oxide (eNO), and restore essential fatty acid (EFA) metabolism to normal and enhance the formation of lipoxin A4 (LXA4), a potent anti-inflammatory, vasodilator and antioxidant. These actions are in addition to the ability of vitamin C to function as an antioxidant. In vitro and in vivo studies revealed that PGE1, PGI2 and NO have cytoprotective and genoprotective actions and thus, protect pancreatic β and vascular endotheilial cells from the cytotoxic actions of endogenous and exogenous toxins. AA, the precursor of LXA4 and LXA4 have potent anti-diabetic actions and their plasma tissue concentrations are decreased in those with diabetes mellitus and hypertension. Thus, vitamin C by augmenting the formation of PGE1, PGI2, eNO, LXA4 and restoring AA content to normal may function as a cytoprotective, anti-mutagenic, vasodilator and platelet anti-agregator actions that explains its benefical action in type 2 diabetes mellitus and hypertension.

Nutritional factors in the prevention and management of coronary artery disease and heart failure

Nutritional factors such as magnesium, folic acid, vitamins B12 and B6, L-arginine, and polyunsaturated fatty acids (PUFAs) appear to be significantly beneficial for patients with coronary artery disease (CAD), and in the prevention and arresting the progression of HF and cardiac arrhythmias. Additionally, ingestion of adequate amounts of protein and maintaining normal concentrations of plasma albumin seem to be essential for these patients. These nutrients closely interact with the metabolism of L-arginine-nitric oxide (NO) system, essential fatty acids, and eicosanoids such that beneficial products such as NO, prostaglandin E1, prostacyclin, prostaglandin I3, lipoxins, resolvins, and protectins are generated and synthesis of proinflammatory cytokines is suppressed that results in platelet anti-aggregation, vasodilation, angiogenesis, and prevention of CAD, cardiac arrhythmias, and stabilization of HF. This implies that individuals at high risk for CAD, cardiac arrhythmias, and HF and those who have these diseases need to be screened for plasma levels of magnesium, folic acid, vitamins B12 and B6, L-arginine, NO, various PUFAs, lipoxin A4, resolvins, protectins, asymmetrical dimethylarginine (an endogenous inhibitor of NO), albumin, and various eicosanoids and cytokines and correct their abnormalities to restore normal physiology.

The effects on plasma, red cell and platelet fatty acids of taking 12 g/day of ethyl-eicosapentaenoate for 16 months: dihomogammalinolenic, arachidonic and docosahexaenoic acids and relevance to Inuit metabolism

A patient with mantle cell lymphoma took 12g/day of ethyl-eicosapentaenoate for 16 months. Compared to reference values, eicosapentaenoic and docosapentaenoic acids were elevated in plasma, red cells and platelets but docosahexaenoic acid levels were in the normal range. Arachidonic acid levels were moderately reduced but dihomogammalinolenic acid levels remained in the normal range. In spite of a long chain n-3 fatty acid intake higher than in most Inuit populations, arachidonic acid levels remained considerably higher in this patient than in the Inuit. The implications for understanding of fatty acid metabolism in humans are discussed.

Biochemical deficiency of pyridoxine does not affect interleukin-2 production of lymphocytes from patients with Sjögren's syndrome

BACKGROUND

There is evidence that pyridoxine deficiency may alter the immune response. It is not known whether a deficiency of this vitamin is evident in subjects with primary Sjögren's syndrome (SS).

OBJECTIVE

We studied whether subjects with primary SS showed a biochemical deficiency of pyridoxine, and if it is associated with abnormal production of interleukin-2 from lymphocytes stimulated in vitro with phytohemagglutinin (PHA).

DESIGN

Two studies were conducted, (i) biochemical and nutritional assessments were performed in a cross-over study in subjects with primary SS, who were supplemented with 25 mg/day of pyridoxine or placebo for 3 months. After 1 month washout, they were supplemented for 3 months with placebo, (ii) patients with SS and matched controls received pyridoxine or placebo for 45 days, and a blood sample was obtained to study IL-2 production and expression in T-lymphocytes stimulated with PHA.

RESULTS

Subjects with primary SS showed limited dietary intake of pyridoxine and biochemical deficiency of this vitamin assessed through the activation coefficient of the erythrocyte aspartate aminotransferase. The biochemical deficiency did not affect production nor mRNA expression of IL-2 from T-lymphocytes stimulated in vitro with PHA compared with the control group. Supplementation of subjects with primary SS with 25 mg/day with pyridoxine for 45 days did not produce any significant change as compared to those patients supplemented with placebo.

CONCLUSIONS

Subjects with primary SS showed biochemical deficiency of pyridoxine, possibly due to limited intake of this vitamin which was corrected by supplementation with pyridoxine. However, IL-2 production and mRNA expression from stimulated lymphocytes were unaffected by supplementation, probably because the deficiency was not severe enough to affect the immune system.

SPONSORSHIP

This work was supported by the National Council of Science and Technology (CONACYT), Mexico, grant no. 212226-5-0902PM.

The effect of ascorbate on essential fatty acid composition in B16 melanoma cells

Ascorbate has been shown to be involved in essential fatty acid (EFA) metabolism, resulting in the suggestion that the effect of ascorbate on cell growth may be mediated through an influence on the metabolism of these FAs. This study examined the effect of ascorbate, supplemented over the nutritional concentration range of 0-100 micrograms/ml, on the in vitro cell growth of non-malignant LLCMK (monkey kidney) cells and malignant B16 murine melanoma cells. The effect of ascorbate on EFA composition was also investigated, and involved the determination of the levels of linoleic acid (LA), gamma-linoleic acid (GLA), dihomogammalinolenic acid (DGLA) and arachidonic acid (AA) present in the stroma and membrane of the two cell types. Ascorbate had no significant inhibitory or stimulatory effect on the growth of either the LLCMK or B16 cells. EFA levels detected in the LLCMK cells were generally higher than those detected in the B16 cells. The % composition of the various EFAs in the stroma fractions of the two cell types were higher than the level of the corresponding EFAs in the membrane fractions. GLA levels were not detectable in the membrane fractions of the B16 cells. AA % composition determined in both cell types, was greater than that of any other EFA % composition.

Enhanced prostaglandin synthesis as a mechanism for inhibition of melanoma cell growth by ascorbic acid

Both ascorbic acid and the 1-series prostaglandins have been reported to be important regulators of cell growth and since ascorbic acid also increases the synthesis of the 1-series prostaglandins, it is possible that the effects of ascorbic acid on cell growth might be mediated by changes in 1-series prostaglandin synthesis induced by ascorbic acid. This study attempted to examine this possible relationship. The effects of ascorbic acid, prostaglandin E1 and the essential fatty acid precursors of the prostaglandins, linoleic acid and gamma-linolenic acid on the in vitro growth of transformed BL6 murine melanoma cells and untransformed monkey kidney (LLCMK) cells was determined. The effects of ascorbic acid addition on the growth inhibitory effect of the essential fatty acids and on the activity of delta-6-desaturase, a key enzyme in 1-series prostaglandin synthesis were also examined. Addition of ascorbic acid, prostaglandin E1 and both essential fatty acids was found to reduce BL6 growth while PGE1 and to a lesser extent the essential fatty acids reduced LLCMK cell growth. The growth inhibitory effect of the essential fatty acids was enhanced by ascorbic acid which was also found to stimulate delta-6-desaturase activity in BL6 cells. The growth inhibitory effect of ascorbic acid on BL6 cells may thus be mediated by changes in prostaglandin synthesis through an association with the metabolism of the essential fatty acid precursors of the prostaglandins.

On the synthesis of prostaglandins E1, E2 and E2 alpha by sow oviducts. Differential modulation of 1 and 2 series of prostaglandins by norepinephrine

The present study was performed in order to evaluate whether norepinephrine (NE) can modulate the synthesis and release of 1 and 2 series of prostaglandins (PGs) by the isthmic region of preovulatory sow oviducts and also to clarify whether the action of the neurotransmitter is mediated through alpha, through beta or through both types of tissue adrenoreceptors. NE, at a concentration of 1 microgram/ml, depressed significantly (P less than 0.05) the basal output of PGE1 and enhanced (P less than 0.01) the release of PGE2 but, did not modify, the output of "PGF2 alpha-like material". Propranolol (10(-7)M) failed to alter the basal output of "PGE1, PGE2 or PGF2 alpha-like material". In the presence of this beta-adrenoreceptor blocker, the depression induced by NE on PGE1 output, was abolished; its stimulatory influence on the release of PGE2, was eliminated and no effect was detected regarding PGF2 alpha. On the other hand, phentolamine (10(-6)M) did not alter the basal output of "PGE1, PGE2 or PGF2 alpha-like material" and also failed to modify the depression induced by NE on PGE1 release. However, this alpha adrenoceptor blocker completely inhibited the stimulatory action of NE on the output of PGE2 into the incubating medium. The foregoing results document opposite actions of NE on PGE1 and PGE2 outputs from the isthmic region of proestrous sow oviducts and suggest the involvement of beta-adrenoreceptors in both disparate influences. The activation of alpha adrenoreceptors also appears associated with the enhancing effect of the agonist on the release of PGE2. The possible physiological significance of these findings is discussed in terms of the function of the isthmic region as an "adrenergic sphincter" able to influence ovum transport around the moment of ovulation.

The antithrombotic effect of prostaglandin E1 immobilized on albuminated polymer matrix

For intravascular implantation, a biofunctional surface seems to retard surface thrombosis upon synthetic materials. Prostaglandins, like PGI2, PGE1, and PGD2, etc., are believed to stimulate membrane-bound adenyl cyclase and thereby raise intracellular levels of c-AMP within platelets, which inhibit platelet adhesion and aggregation. A new procedure is suggested for the immobilization of prostaglandin E1 on an albuminated polymer matrix, through glutaraldehyde coupling. Materials thus prepared show dramatic antiplatelet effects, with regard to platelet adhesion, when compared with albumin-immobilized surfaces. The affinity of various modified surfaces toward platelet adhesion is studied, using washed platelets suspended in Tyrode's solution. Octane contact angle studies are used to develop an understanding of the varied nature of bound substrates at equilibrium on polymer surfaces. These are studied at the solid/liquid interface, which is closest to in vivo conditions. The plasma recalcification time demonstrates the anticoagulant properties of various surfaces. A possible role of PGE1 in reducing platelet activity in the presence and absence of vitamin C is discussed. This technique may be used in the development of non-thrombogenic surfaces on existing biomedical polymers. Simultaneous pharmaceutical modification of the blood with vitamin C may enhance the blood compatibility of the surface.

Essential fatty acid metabolism in diseases of connective tissue with special reference to scleroderma and to Sjogren's syndrome

Drugs which modify the conversion of essential fatty acids to prostaglandins and leukotrienes are the mainstays of treatment in rheumatology. Yet these drugs have little or no action in scleroderma or Sjogren's syndrome and under some circumstances may have adverse effects. Patients with scleroderma have been shown to have very high levels of circulating prostaglandins, coupled with depletion of the prostaglandin precursors, dihomogammalinolenic acid and arachidonic acid. Levels of the metabolites of arachidonic acid, 22:4n-6 and 22:5n-6, which have major roles in maintaining normal cell membrane characteristics were exceptionally low in both plasma and red cell membranes. Others have observed that various functions are highly resistant to normal actions of PGs in scleroderma. This raises the possibility that the high rate of PG formation in scleroderma may be beneficial, in compensation, and that clinical symptoms develop when PG precursors begin to be depleted. Red cell membrane fatty acids patterns in Sjogren's syndrome are almost identical to those in scleroderma. Placebo-controlled trials of supplementation with essential fatty acids have been found to be beneficial in both scleroderma and Sjogren's syndrome.

Effects of ascorbic acid deficiency on the in vitro biosynthesis of cyclooxygenase metabolites in guinea pig lungs

Endogenous levels of ascorbic acid may play a role in regulating the biosynthesis of cyclooxygenase metabolites in lungs of male guinea pigs. The in vitro biosyntheses of prostaglandins, prostacyclin and thromboxane were examined using isolated microsomal membranes from control and ascorbic acid deficient guinea pigs, under conditions in which the substrate concentration ( [3H]-arachidonic acid) was varied from 10-100 microM. Maintenance of guinea pigs for two weeks on an ascorbic acid deficient diet did not alter lung/body weight ratios, nor protein content of the lungs. Lung microsomes from ascorbic acid deficient guinea pigs demonstrated a greater biosynthesis of total cyclooxygenase metabolites at low substrate concentrations. A significant increase in the PGF2 alpha synthesis was observed in the scorbutic microsomes at 20 microM arachidonic acid. At higher substrate concentrations the production of PGF2 alpha was significantly reduced in ascorbic acid deficient animals. By contrast, biosynthesis of thromboxane or prostacyclin in treated animals was not significantly different from control microsomes. At a substrate concentration of 100 microM, there was equivalent synthesis of total cyclooxygenase metabolites in control and vitamin C deficient animals. The changes in prostaglandin biosynthesis were not due to an interaction of ascorbic acid with glutathione levels in the lung. These results support the hypothesis that ascorbic acid may modulate cyclooxygenase activity in the lung in a substrate dependent nature.

Metabolic factors regulating the generation of prostaglandins E1 and E2 by isolated rat uterus

The generation and output of PGE2 and PGE1 by isolated rat uterus incubated with or without glucose as well as the influence of different metabolic substrates and selective enzyme inhibitors on tissue formation and release of PGE material of the 1 and 2 series, were explored. The output of PGE2 was comparable with glucose, fructose, lactate or pyruvate as the substrate but diminished significantly in citrate-containing solution. In substrate-free media uteri released more PGE2 than in the presence of glucose or other substrates. The PGE1 liberated was similar in glucose, fructose, lactate or pyruvate and decreased significantly in citrate or without substrate. 2-deoxy-D-glucose (2-DG), fluoride or arsenite failed to alter significantly the release of PGE2 whereas 2,4-dinitrophenol (DNP) evoked augmentation. The uterus released less PGE1 after 2-DG or fluoride but not following the addition of DNP or arsenite. The results suggest that the synthesis and release of PGE2 and PGE1 in the isolated rat uterus appear to be selectively modulated by different tissue metabolic pathways.

Melanin: the organizing molecule

The hypothesis is advanced that (neuro)melanin (in conjunction with other pigment molecules such as the isopentenoids) functions as the major organizational molecule in living systems. Melanin is depicted as an organizational "trigger" capable of using established properties such as photon-(electron)-phonon conversions, free radical-redox mechanisms, ion exchange mechanisms, and semiconductive switching capabilities to direct energy to strategic molecular systems and sensitive hierarchies of protein enzyme cascades. Melanin is held capable of regulating a wide range of molecular interactions and metabolic processes primarily through its effective control of diverse covalent modifications. To support the hypothesis, established and proposed properties of melanin are reviewed (including the possibility that (neuro)melanin is capable of self-synthesis). Two "melanocentric systems"--key molecular systems in which melanin plays a central if not controlling role--are examined: 1) the melanin-purine-pteridine (covalent modification) system and 2) the APUD (or diffuse neuroendocrine) system. Melanin's role in embryological organization and tissue repair/regeneration via sustained or direct current is considered in addition to its possible control of the major homeostatic regulatory systems--autonomic, neuroendocrine, and immunological.

The distribution of ascorbic acid between various cellular components of blood, in normal individuals, and its relation to the plasma concentration

1. A study was undertaken to investigate the distribution of ascorbic acid between various cellular components of blood, in normal individuals, and its relation to the plasma concentration. Forty-one unsupplemented individuals and sixteen supplemented (2 g/d for 5 d) individuals were studied. 2. Granulocytes, mononuclear leucocytes, platelets and erythrocytes were separated by differential sedimentation and centrifugation. Ascorbic acid contents were measured by the dinitrophenylhydrazine method. 3. Ascorbic acid content per cell was higher in mononuclear leucocytes and granulocytes than in platelets and erythrocytes. Intracellular ascorbic acid concentrations, calculated from published values for cell volumes, when compared with the plasma concentration showed a marked ability to concentrate ascorbic acid in mononuclear leucocytes (80 times), platelets (40 times) and granulocytes (25 times). 4. Erythrocytes showed little ability to concentrate ascorbic acid over the normal range of plasma concentration but because of their relative numbers they and the plasma fraction accounted for most of the blood-borne ascorbic acid (greater than 70%). 5. The ascorbic acid content of granulocytes, platelets and erythrocytes showed a significant positive correlation with the plasma concentration and supplementation with ascorbic acid significantly increased the content of these cell types. Mononuclear leucocytes in contrast did not show any such relationship. 6. The ability of the mononuclear leucocytes to maintain the highest levels of ascorbic acid in the cell types studied, despite variation in plasma availability, warrants further study, particularly in view of the importance of these cells in immunocompetence.

Does hypoxia selectively stimulate the generation of prostaglandin E1 by the isolated rat uterus?

The contractile activity of uterine horns maintained for 90 to 120 minutes under normal oxygenation (carbogen or 100% O2) became undetectable. When in this condition the gassing was stopped one or two minutes later, regular phasic contractions appeared super-imposed on a small increment of the basal resting tone. Indomethacin and aspirin well known inhibitors of prostaglandin (PG) synthesis, blocked the contractile influence of hypoxia whereas neither tranylcypromine or imidazole were able to alter the stimulatory action. PGE2, PGE1 and PGF2 alpha released into the bathing solution during 10 minutes of normoxia or 10 minutes of hypoxia, were measured. Under O2, PGE2 and PGF2 alpha production diminished significantly (P less than 0.05 and P less than 0.01, normoxia vs. hypoxia, respectively) whereas PGe1 increased (P less than 0.05). "PGI2-like material" generated was also detected and it was found that the values during hypoxia were lower than those observed in O2; however the difference was not statistically significant. Dose-response contractile activity to PGs with and without gassing was explored. It was necessary to add 100 times more PGF2 alpha to obtain the minimal response under hypoxic conditions as compared to normoxia. On the other hand the threshold response to PGE1 was 10 times lower under hypoxic conditions than in normoxia. The possible mechanism(s) that induce an increment in PGE1 generation accompanied by a simultaneous decrement of PGE2 during hypoxia is discussed in connection with a possible role of PGE1 evoking uterine contractions when the gassing of the suspending solution is stopped.

Loss of delta-6-desaturase activity as a key factor in aging

Aging is characterized by a wide variety of defects, particularly in the cardiovascular and immune systems. Cyclic AMP levels fall, especially in lymphocytes. Delta-6-desaturase (D6D) levels have been found to fall rapidly in the testes and more slowly in the liver in aging rats. D6D is an enzyme which converts cis-linoleic acid to gamma-linolenic acid (GLA). Other factors which inhibit D6D activity are diabetes, alcohol and radiation, all of which may be associated with accelerated aging. In meat eaters or omnivores which can acquire arachidonic acid from food, the main consequences of D6D loss will be deficiencies of GLA, dihomogamma-linolenic acid (DGLA) and prostaglandin (PG) E1. PGE1 activates T lymphocytes, inhibits smooth muscle proliferation and thrombosis, is important in gonadal function and raises cyclic AMP levels in many tissues. It is a good candidate for a key factor lost in aging. Moderate food restriction, the only manoeuvre which consistently slows aging in homoiotherms, raises D6D activity by 300%. Other factors important in regulating D6D and the conversion of GLA to PGE1 are zinc, pyridoxine, ascorbic acid, the pineal hormone, melatonin, and possibly vitamin B3. GLA administration to humans has been found to lower blood pressure and cholesterol, and to cause clinical improvement in patients with Sjogren's syndrome, scleroderma and alcoholism. These diseases are associated with some features of accelerated aging. The proposition that D6D loss is not only a marker of aging but a cause of some of its major manifestations is amenable to experimental test even in humans. The blocked enzyme can be by-passed by giving GLA directly.

Ascorbic acid and pyridoxine in experimental anaphylaxis

Two vitamins, ascorbic acid (AA) and pyridoxine have been suggested by others as useful drugs for the treatment of bronchial asthma, although the views concerning AA or controversial. We have tested both vitamins in some models of histamine release and experimental anaphylaxis. AA does not inhibit mast cell degranulation induced by phospholipase A and histamine release from isolated rat mast cells induced by compound 48/80 or antigen (egg albumin). On the contrary, in the latter tests pyridoxine exerts inhibition in a range of concentrations from 10(-3)-10(-2) M. We conclude: 1. There is no experimental basis for considering ascorbic acid as a prophylactic antiasthmatic drug as is disodium cromoglycate. 2. Pyridoxine must receive additional basic and clinical investigations in this field.

Point of view--a role for "nutritional insurance" supplementation in preventive medicine

While macronutrient dietary profile is receiving increasing attention as a determinant of disease risk, the potential of micronutrient supplementation as a public health tool has received little serious attention within orthodox medical circles. In light of the fact that the biochemical effects of many nutrients vary as a function of dose within and beyond "adequate" intake levels, and in light of individual differences in nutrient requirements, it is evident that micronutrient dietary profile--even under the assumption that all nutrient intakes are at least "adequate" or "normal"--plays a major role in determining long-term disease risk. Intelligently planned "nutritional insurance" supplementation could be expected to prevent or delay the onset of many degenerative diseases, while helping to satisfy idiosyncratically high requirements and preventing nutrient deficiency disease.

A biochemical basis for alcoholism and alcohol-induced damage including the fetal alcohol syndrome and cirrhosis: interference with essential fatty acid and prostaglandin metabolism

Alcohol has at least two actions on essential fatty acid (EFA) and Prostaglandin (PG) metabolism. It enhances the conversion of dihomogammalinolenic acid (DGLA) to PGE1 but it blocks the activity of the delta-6-desaturase, an enzyme necessary for replenishment of DGLA stores from dietary precursors. The acute effect of ethanol is therefore an increased production of PGE1 but chronic consumption will lead to depletion of DGLA and PGE1. Withdrawal from alcohol will lead to a precipitous fall in PGE1. PGE1 is known to have profound effects on the nervous system and behaviour. Patients with mania produce more PGE1 than normal while those with depression make less. Alcoholics may drink to maintain a normal PGE1 level, something which will require more and more ethanol as DGLA is depleted. In both animals and humans PGE1 or its precursor, gamma-linolenic acid (GLA) have been shown to attenuate the acute withdrawal syndrome. PGE1 injections prevent the development of fatty liver in alcohol-treated animals. Defective EFA and PGE1 metabolism are known to lead to increased fibrosis, reproductive failure, cardiomyopathy, cardiovascular disorders, gastritis and pancreatitis and could therefore be the basis for these disorders in alcoholics. A PGE1 deficiency could also be responsible for the fetal alcohol syndrome. Three other agents are known to produce constellations of fetal defects very similar to those found in the alcohol syndrome. These other factors are dihphenylhydantoin, lithium, and a deficiency of zinc. These three factors and excessive alcohol consumption all lead to PGE1 deficiency by different routes. If this concept is correct, the key to the management of alcoholism and its medical complications lies in the provision of GLA or DGLA, fatty acids which by-pass the alcohol blocked step and which are unfortunately unlikely to be present in any normal diet. Unlike many concepts of alcoholism and alcohol damage, the EFA/PGE1 idea is very readily testable and already has considerable experimental support.

A new concept of lifestyle-related cardiovascular disease: the importance of interactions between cholesterol, essential fatty acids, prostaglandin E1 and thromboxane A2

A proposal to account for the inter-relationships between established risk factors and cardiovascular disease is presented. In this concept, the critical substance is prostaglandin (PG) E1 which is a vasodilator, an inhibitor of platelet aggregation, an inhibitor of cholesterol and collagen biosynthesis and an inhibitor of smooth muscle proliferation. PGE1 biosynthesis is enhanced by the essential fatty acid, linoleic acid, by the platelet aggregating agent thromboxane (TX) A2, by cholesterol and by melatonin. These factors may participate in a negative feedback control loop. As a result of the operation of this loop, any tendency for PGE1 levels to fall is followed by increased cholesterol and TXA2 biosynthesis, and enhanced platelet aggregation, vasoconstriction, smooth muscle proliferation and collagen biosynthesis. Enhancement of PGE1 biosynthesis will have the opposite effects. Factors known to increase PGE1 biosynthesis include essential fatty acids, vitamin C, ethanol, pyridoxine, zinc and probably niacin, all of which are known to have some protective effects against cardiovascular disease. The hypothesis predicts that lowering of cholesterol biosynthesis by any method other than enhanced PGE1 formation, while reducing the risk of cardiovascular disease, will increase the risk of other disorders. The hypothesis suggest new approaches to treatment and new ways of combining existing treatments. Colchicine, which at low concentrations may imitate and action of melatonin, has particularly interesting possibilities. Colchicine and related compounds have already been shown to have potent cholesterol-lowering and anti-atherogenic actions in both humans and animals.

Development of a papillary thyroid carcinoma in a patient while on high dosage ascorbic acid therapy

A case of reticulum cell sarcoma apparently successfully treated with mega ascorbic acid therapy is described briefly. While the patient continued a large maintenance dose of ascorbic acid, a papillary thyroid carcinoma developed clinically. The role of ascorbic acid in the body resistance to cancer and in tumour prevention is discussed.

The reversibility of cancer: the relevance of cyclic AMP, calcium, essential fatty acids and prostaglandin E1

Transformed cells in culture can be normalised (made to undergo reverse transformation) by exposure to cyclic AMP, prostaglandin (PG) E1 and certain drugs. One of these drugs, thioproline, has been successfully used in treating human cancer. All cancer cells have a number of common characteristics: they exhibit aerobic glycolysis, they fail to show feedback regulation of cholesterol biosynthesis, they do not regulate cytoplasmic calcium levels normally and they produce excessive amounts of 2 series PGs. It has been known since 1975 that transformed cells cannot make PGE1 because of loss of the delta-6-desaturase enzyme which converts linoleic acid to gamma-linolenic acid. There is evidence that PGE1 acting in concert with thromboxane A2 has effects which make it able to reverse all the metabolic abnormalities common to all cancer cells. It is therefore argued that loss of the ability to make PGE1 and/or thromboxane A2 may be the critical step in malignant change in many forms of cancer. Restoration of normal PGE1 synthesis by providing gamma-linolenic or dihomogammal inolenic acids which will by-pass the blocked desaturase, whould be of value in normalising malignant cells and reversing cancer growth. Since this approach is completely non-toxic it is here seriously suggested that it might be used as a first step in treatment of those cancers where current evidence suggests that delay in the administration of orthodox treatment is unlikely to affect prognosis.

Sjogren's syndrome and the sicca syndrome: the role of prostaglandin E1 deficiency. Treatment with essential fatty acids and vitamin C

Lack of adequate synthesis of prostaglandin (PG) E1 may be the key factor in Sjogren's syndrome. PGE1 is important for lacrimal and salivary gland secretion and for T lymphocyte function: a deficiency could therefore account for the main features of Sjogren's syndrome and the sicca syndrome. PGE1 could also account for many of the other features often associated with these syndromes. These include the Raynaud's phenomenon, the abnormalities of renal function and the precipitation of the syndrome by vitamin C deficiency. Vitamin C is important in PGE1 biosynthesis. PGE1 treatment has been shown to correct the immunological abnormalities in the NZB/W mouse, the animal model of Sjogren's syndrome. An attempt to treat humans with Sjogren's syndrome by raising endogenous PGE1 production by administration of essential fatty acid PGE1 precursors, of pyridoxine and of vitamin C was successful in raising the rates of tear and saliva production.

Interactions between zinc, essential fatty acids and prostaglandins: relevance to acrodermatitis enteropathica, total parenteral nutrition, the glucagonoma syndrome, diabetes, anorexia nervosa and sickle cell anaemia

Many of the features of zinc deficiency and of essential fatty acid (EFA) deficiency are similar in both animals and humans. The two agents interact in various ways. EFAs are important in zinc absorption, probably after conversion to prostaglandins (PGs). Zinc seems necessary for at least two stages in EFA metabolism, the conversion of linoleic acid to gamma-linolenic acid, and the mobilisation of dihomogammalinolenic acid (DGLA) for the synthesis of 1 series PGs. Zinc may also be important in the conversion of DGLA to arachidonic acid and in arachidonic acid mobilisation for 2 series PG formation. These interactions shed considerable light on a number of clinical syndromes, including acrodermatitis enteropathica, total parenteral nutrition, diabetes mellitus, the glucagonoma syndrome and sickle cell anaemia. There is substantial evidence to suggest that anorexia nervosa is due to a combined deficiency of zinc and EFAs. Understanding of the roles of zinc and EFAs in these various clinical situations is likely to lead to improved therapy.

The nutritional regulation of T lymphocyte function

Prostaglandin (PG) E1 plays a major role in the regulation of thymus development and T lymphocyte function and the evidence for this is reviewed. The production of PGE1 is dependent on nutritional factors with linoleic acid, gamma-linolenic acid, pyridoxine, zinc and vitamin C playing key roles. Inadequate intake of any one of these will lead to inadequate PGE1 formation and defective T lymphocyte function. Megadoses of any one are likely to be only minimally effective in the absence of adequate intakes of the others. By careful attention to diet it should be possible to activate T lymphocyte function in the large number of diseases including rheumatoid arthritis, various auto-immune diseases, multiple sclerosis, and cancer in which such function is defective. It is possible that T lymphocytes may require both endogenous and exogenous PGE1 in order to function adequately. It is therefore of particular interest that many cancer cells and virally infected cells are unable to make PGE1 because they cannot convert linoleic acid to gamma-linolenic acid. The direct provision of gamma-linolenic or dihomo-gammalinolenic acids in these situations is worthy of full investigation.

Differential regulation of the formation of prostaglandins and related substances from arachidonic acid and from dihomogammalinolenic acid. II. Effects of vitamin C

Vitamin C over the concentration range 10 to 100 microgram/ml (5.7-57 x 10-5 M) caused a dose dependent and highly significant enhancement of conversion of 14C-dihomogammalinolenic acid (DGLA) to prostaglandin (PG) E1 and to thromboxane (Tx) B1 by human platelets. Vitamin C had no effect on conversion of 14C-arachidonic acid to PGE2 and TxB2. The concentration range is relevant to physiology: in some cells which concentrate the vitamin, such as polymorphonbuclear leucocytes and the adrenal cortex, vitamin C concentrations may be substantially higher than 100 microgram/ml. Vitamin C can therefore selectively enhance the formation of cyclo-oxygenase generated products from DGLA without changing formation of those from AA. This effect can account for a number of the known actions of vitamin C including its effect on the immune system. The implications of this finding are discussed.