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Bleomycin is a commonly used anti-cancer drug in the management of a variety of cancers. Previously, we showed that arachidonic acid (AA) augmented the growth inhibitory action of bleomycin on IMR-32 (human neuroblastoma cells) in vitro by enhancing oxidative stress. Despite these results, the exact molecular mechanism of cytotoxic action of bleomycin and its augmentation by AA is not known. Our current study revealed that a combination of bleomycin and AA significantly enhanced the expression of FAS gene, which is involved in programmed cell death (apoptosis) and caspases 3 and 8 compared to either bleomycin or AA alone implying that activation of extrinsic apoptotic pathway plays a major role in their (bleomycin + AA) tumoricidal action. It is interesting to note that AA by itself enhanced the expression of FAS and caspases 3 and 8 compared to control. Since caspases have a role in inflammation, cell proliferation, tumour suppression, cell differentiation, neural development and axon guidance and ageing, this may explain pleiotropic actions of AA and their metabolites., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In both type 1 and type 2 diabetes mellitus, increased production of pro-inflammatory cytokines and reactive oxygen species (ROS) occurs that induce apoptosis of β cells and cause peripheral insulin resistance respectively though the degree of their increased production is higher in type 1 and less in type 2 diabetes mellitus. Despite this, the exact mechanism(s) that lead to increased production of pro-inflammatory cytokines: interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and ROS is not known. Studies showed that plasma concentrations of arachidonic acid (AA) and lipoxin A4 (LXA4) are low in alloxan-induced type 1 diabetes mellitus in experimental animals and patients with type 2 diabetes mellitus. Prior administration of AA, eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively) and transgenic animals that produce increased amounts of EPA and DHA acids were protected from chemical-induced diabetes mellitus that was associated with enhanced formation of LXA4 and resolvins, while protectin D1 ameliorated peripheral insulin resistance. AA, LXA4, resolvins and protectins inhibit IL-6 and TNF-α production and suppress ROS generation. Thus, AA and lipoxins, resolvins and protectins may function as endogenous anti-diabetic molecules implying that their administration could be useful in the prevention and management of both types of diabetes mellitus., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Radiation induces overexpression and activity of the MET oncogene that, in turn, enhances the production of prostaglandin E(2), a pro-inflammatory molecule. Prostaglandin E(2) promotes tumor cell invasion, prevents apoptosis, enhances their metastasis and causes radioresistance. It is proposed that lipoxin A(4), a potent endogenous anti-inflammatory molecule, opposes the actions of prostaglandin E(2) and thus, could promote radiosensitivity, suppress tumor cell proliferation, invasiveness and suppress metastasis. Thus, methods designed to enhance endogenous lipoxin A(4) formation or its synthetic analogs may be useful in the management of cancer., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Phenytoin sodium/diphenyl hydantoin (DPH) is used by a major segment of epileptics and neuro surgery patients with head injury to prevent seizures. DPH is a known mutagen, carcinogen, and teratogen. Essential fatty acids (EFAs) are critical for various tissues and were reported to act as anti-mutagenic agents. In the present study we assessed the effect of five EFAs on DPH-induced genetic damage both in vitro and in vivo. DPH induced significant genetic damage. Of all the EFAs (linoleic acid, alpha-linolenic acid, gamma-linolenic acid, arachidonic acid, dihomo-gamma-linolenic acid, and eicosapentaenoic acid) studied, all except eicosapentaenoic acid showed significant decrease in DPH induced genetic damage as assessed by micronucleus (MN) test. However, gamma-linolenic acid (GLA) was found to be the most effective in reducing the number of MN containing lymphocytes both in vitro and in vivo to control values. EFAs when tested alone produced insignificant increase in the amount of genetic damage but when tested in combination with DPH the number of micronuclei containing lymphocytes was reduced; but the DNA ladder pattern, an indication of DNA damage, was increased. This apparently paradoxical action of EFAs, especially of GLA, suggests that, in all probability, fatty acids induce apoptosis of cells that harbor significant DNA damage. Based on these results we suggest that GLA functions as a unique endogenous molecule that protects cells from accumulating genetic damage.

Polyunsaturated fatty acids (PUFAs) are essential structural components of all cell membranes and, more so, of the central nervous system. Several studies revealed that n-3 PUFAs possess anti-inflammatory actions and are useful in the treatment of dyslipidemia. These actions explain the beneficial actions of n-3 PUFAs in the management of cardiovascular diseases, inflammatory conditions, neuronal dysfunction, and cancer. But, the exact molecular targets of these beneficial actions of n-3 PUFAs are not known. Mice engineered to carry a fat-1 gene from Caenorhabditis elegans add a double bond into an unsaturated fatty acid hydrocarbon chain and convert n-6 to n-3 fatty acids. This results in an abundance of n-3 eicosapentaenoic acid and docosapentaenoic acid specifically in the brain and a reduction in n-6 fatty acids of these mice that can be used to evaluate the actions of n-3 PUFAs. Gene expression profile, RT-PCR and protein microarray studies in the hippocampus and whole brain of wild-type and fat-1 transgenic mice revealed that genes and proteins concerned with inflammation, apoptosis, neurotransmission, and neuronal growth and synapse formation are specifically modulated in fat-1 mice. These results may explain as to why n-3 PUFAs are of benefit in the prevention and treatment of diseases such as Alzheimer's disease, schizophrenia and other diseases associated with neuronal dysfunction, low-grade systemic inflammatory conditions, and bronchial asthma. Based on these data, it is evident that n-3 PUFAs act to modulate specific genes and formation of their protein products and thus, bring about their various beneficial actions.

Low blood folate and raised homocysteine concentrations are associated with poor cognitive function. Folic acid supplementation improves cognitive function. Folic acid enhances the plasma concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). EPA, DHA, and arachidonic acid (AA) are of benefit in dementia and Alzheimer's disease by up-regulating gene expression concerned with neurogenesis, neurotransmission and connectivity, improving endothelial nitric oxide (eNO) generation, enhancing brain acetylcholine levels, and suppressing the production of pro-inflammatory cytokines. EPA, DHA, and AA also form precursors to anti-inflammatory compounds such as lipoxins, resolvins, and neuroprotectin D1 (NPD1) that protect neurons from the cytotoxic action of various noxious stimuli. Furthermore, various neurotrophins and statins enhance the formation of NPD1 and thus, protect neurons from oxidative stress and prevent neuronal apoptosis Folic acid improves eNO generation, enhances plasma levels of EPA/DHA and thus, could augment the formation of NPD1. These results suggest that a combination of EPA, DHA, AA and folic acid could be of significant benefit in dementia, depression, and Alzheimer's disease and improve cognitive function.

Atherosclerosis is a dynamic process. Dyslipidemia, diabetes mellitus, hypertension, obesity, and shear stress of blood flow, the risk factors for the development of atherosclerosis, are characterized by abnormalities in the metabolism of essential fatty acids (EFAs). Gene expression profiling studies revealed that at the sites of atheroslcerosis-prone regions, endothelial cells showed upregulation of pro-inflammatory genes as well as antioxidant genes, and endothelial cells themselves showed changes in cell shape and proliferation. Uncoupled respiration (UCP-1) precedes atherosclerosis at lesion-prone sites but not at the sites that are resistant to atherosclerosis. UCP-1 expression in aortic smooth muscle cells causes hypertension, enhanced superoxide anion production and decreased the availability of NO, suggesting that inefficient metabolism in blood vessels causes atherosclerosis without affecting cholesterol levels. Thus, mitochondrial dysfunction triggers atherosclerosis. Atherosclerosis-free aortae have abundant concentrations of the EFA-linoleate, whereas fatty streaks (an early stage of atherosclerosis) are deficient in EFAs. EFA deficiency promotes respiratory uncoupling and atherosclerosis. I propose that a defect in the activity of Delta6 and Delta5 desaturases decreases the formation of gamma-linolenic acid (GLA), dihomo-DGLA (DGLA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) from dietary linoleic acid (LA) and alpha-linolenic acid (ALA). This, in turn, leads to inadequate formation of prostaglandin E1 (PGE1), prostacyclin (PGI2), PGI3, lipoxins (LXs), resolvins, neuroprotectin D1 (NPD1), NO, and nitrolipids that have anti-inflammatory and platelet anti-aggregatory actions, inhibit leukocyte activation and augment wound healing and resolve inflammation and thus, lead to the initiation and progression atheroslcerosis. In view of this, it is suggested that Delta6 and Delta5 desaturases could serve as biological target(s) for the discovery and development of pharmaceuticals to treat atherosclerosis.

The effect of gamma-linolenic acid (GLA) and prostaglandin E1 (PGE1) on gamma-radiation, diphenylhydantoin (DPH), benzo(a)pyrene (BP), and 4-alpha-phorbol-induced genetic damage to the bone marrow cells of mice, using the sensitive micronucleus (MN) test was investigated. PGE1 and its precursor GLA prevented gamma-radiation, DPH, BP, and 4-alpha-phorbol-induced genetic damage.

Earlier, we reported that oils rich in omega-3 eicosapentaenoic acid and docosahexaenoic acid and omega-6 gamma-linolenic acid and arachidonic acid prevented the development of alloxan-induced diabetes mellitus in experimental animals. Here we report the results of our studies with pure saturated stearic acid (SA), monounsaturated oleic acid (OA) and omega-6 arachidonic acid (AA) on alloxan-induced diabetes mellitus in Wistar male rats. Prior oral supplementation with AA prevented alloxan-induced diabetes mellitus, whereas both SA and OA were ineffective. Cyclo-oxygenase (COX) and lipoxygenase (LO) inhibitors did not block this protective action of AA against alloxan-induced diabetes, suggesting that both prostaglandins and leukotrienes are not involved, and that AA by itself is effective. Furthermore, AA restored the anti-oxidant status to normal range in various tissues. These results suggest that AA protects pancreatic beta cells against alloxan-induced diabetes in experimental animals by attenuating oxidant stress.

Previously, we observed that alloxan-induced in vitro cytotoxicity and apoptosis in an insulin secreting rat insulinoma, RIN, cells was prevented by prior exposure to prostaglandin (PG) E(1), PGE(2), PGI(2), PGF(1)(alpha), and PGF(3)(alpha) (P<0.05 compared to alloxan), whereas thromboxane B(2) (TXB(2)) and 6-keto-PGF(1)(alpha) were ineffective. In an extension of these studies, we now report that prior intraperitoneal administration of PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) prevented alloxan-induced diabetes mellitus in male Wistar rats, whereas PGI(2), TXB(2), and 6-keto PGF(1)(alpha) were not that effective. PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) not only attenuated chemical-induced diabetes mellitus but also restored the antioxidant status to normal range in red blood cells and pancreas. These results suggest that PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) can abrogate chemically induced diabetes mellitus in experimental animals and attenuate the oxidant stress that occurs in diabetes mellitus.

GLUT-4 (glucose transporter) receptor, tumor necrosis factor-alpha (TNF-alpha), interleukins-6 (IL-6), daf-genes and PPARs (peroxisomal proliferation activator receptors) play a role in the development of insulin resistance syndrome and associated conditions. But, the exact interaction between these molecules/factors and the mechanism(s) by which they produce insulin resistance syndrome is not clear. I propose that a defect in the activity of the enzymes Delta6 and Delta5 desaturases that are essential for the formation of long chain metabolites of essential fatty acids, linoleic acid and alpha-linolenic acid, is a factor in the development of insulin resistance syndrome. Long chain polyunsaturated fatty acids (LCPUFAs) increase cell membrane fluidity and enhance the number of insulin receptors and the affinity of insulin to its receptors; suppress TNF-alpha, IL-6, macrophage migration inhibitory factor (MIF) and leptin synthesis; increase the number of GLUT-4 receptors, serve as endogenous ligands of PPARs, modify lipolysis, and regulate the balance between pro- and anti-oxidants, and thus, play a critical role in the pathogenesis of insulin resistance. In the nematode, Caenorhabditis elegans, the protein encoded by daf-2 is 35% identical to the human insulin receptor; daf-7 codes a transforming growth factor-beta (TGF-beta) type signal and daf-16 enhances superoxide dismutase (SOD) expression. Melatonin has anti-oxidant actions similar to daf-16, TGF-beta and SOD. Calorie restriction enhances the activity of Delta6 and Delta5 desaturases, melatonin production, decreases daf-2 signaling, free radical generation, and augments anti-oxidant defenses that may explain the beneficial effect of diet control in the management of obesity, insulin resistance, and type II diabetes mellitus. These evidences suggest that the activities of Delta6 and Delta5 enzymes play a critical role in the expression and regulation of GLUT-4, TNF-alpha, IL-6, MIF, daf-genes, melatonin, and leptin by modulating the synthesis and tissue concentrations of LCPUFAs. Caloric restriction delays ageing by activating Sir 2 deacetylase in yeast, and expression of Sir 2 (SIRT1) in human cells. Both insulin and insulin-like growth factor-1 (IGF-1) attenuated this response. SIRT1 sequesters the proapoptotic factor Bax, prevents stress-induced apoptosis of cells, and thus, prolongs survival. In addition, SIRT1 repressed PPAR-gamma, and overexpression of SIRT1 attenuated adipogenesis, and upregulation of SIRT in differentiated fat cells triggered lipolysis and loss of fat, events that are known to attenuate insulin resistance and prolong life span. It remains to be seen whether LCPUFAs have a regulatory role in SIRT1 expression and control Sir 2 deacetylase activity. Thus, calorie restriction or reduced food intake has a role not only in the pathobiology of insulin resistance, but also in other associated conditions such as obesity, type II diabetes mellitus, ageing, and longevity.

Endothelial lipase (EL), a new member of the lipase gene family, was recently cloned and has been shown to have a significant role in modulating the concentrations of plasma high-density lipoprotein levels (HDL). EL is closely related to lipoprotein and hepatic lipases both in structure and function. It is primarily synthesized by endothelial cells, functions at the cell surface, and shows phospholipase A1 activity. Overexpression of EL decreases HDL cholesterol levels whereas blocking its action increases concentrations of HDL cholesterol. Pro-inflammatory cytokines suppress plasma HDL cholesterol concentrations by enhancing the activity of EL. On the other hand, physical exercise and fish oil (a rich source of eicosapentaenoic acid and docosahexaenoic acid) suppress the activity of EL and this, in turn, enhances the plasma concentrations of HDL cholesterol. Thus, EL plays a critical role in the regulation of plasma HDL cholesterol concentrations and thus modulates the development and progression of atherosclerosis. The expression and actions of EL in specific endothelial cells determines the initiation and progression of atherosclerosis locally explaining the patchy nature of atheroma seen, especially, in coronary arteries. Both HDL cholesterol and EPA and DHA enhance endothelial nitric oxide (eNO) and prostacyclin (PGI2) synthesis, which are known to prevent atherosclerosis. On the other hand, pro-inflammatory cytokines augment free radical generation, which are known to inactivate eNO and PGI2. Thus, interactions between EL, pro- and anti-inflammatory cytokines, polyunsaturated fatty acids, and the ability of endothelial cells to generate NO and PGI2 and neutralize the actions of free radicals may play a critical role in atherosclerosis.

In the present study, we studied the effect of various prostaglandins (PGs) on alloxan-induced cytotoxicity to rat insulinoma (RIN) cells. Of all the PGs tested, PGE(1), PGE(2), PGI(2), PGF(1 alpha), and PGF(3 alpha) protected RIN cells from alloxan-induced cytotoxicity (P<0.05 compared to alloxan), whereas thromboxane B(2) and 6-keto-PGF(1 alpha) were not effective. PGE(1) induces a statistically significant increase in the activities of superoxide dismutase and glutathione peroxidase and decrease in lipid peroxides in alloxan-treated RIN cells (P<0.001). PGE(1) restored nitric oxide/lipid peroxide ratio to normalcy, suggesting that PGE(1) suppresses oxidant stress induced by alloxan in RIN cells in vitro. Furthermore, PGE(1) prevented DNA damage and apoptosis induced by alloxan. These results indicate that PGE(1) prevents alloxan-induced cytotoxicity to RIN cells in vitro.

Malignant gliomas are among the most devastating of cancers and are a major cause of mortality in a young population with a median survival time of 9 months following cytoreductive surgery, radiotherapy and chemotherapy. Recent studies showed that polyunsaturated fatty acids especially gamma-linolenic acid (GLA) have selective tumoricidal action especially against malignant glioma cells both in vitro and in vivo. Limited open label clinical studies showed that intratumoral injection/infusion of GLA is safe and effective against malignant gliomas. In view of this, large-scale, double blind studies are needed to establish the usefulness of GLA in the treatment of malignant brain tumors.

gamma-Linolenic acid (GLA) is known to have selective tumoricidal action. In this study, the effect of lithium salt of GLA conjugated to iodized lymphographic oil (LGIOC) was injected intra-arterially close to the origin of tumor-feeding vessel(s) was studied. Four patients with stage 4 cancer disease (2 with hepatocellular carcinoma, 1 with giant cell tumor of the bone, and one with renal cell carcinoma), were selected for the study. Angiography, radiography and computed axial tomography were performed prior to and immediately after the injection of LGIOC and at periodic intervals. All four patients tolerated the treatment well. The most significant observation was the complete occlusion of the tumor-feeding vessels after LGIOC injection. Follow-up angiograms performed in all the patients showed occlusion of the tumor-feeding vessels is more or less permanent. A significant reduction in the size of the tumor was also observed in these patients. LGIOC showed occlusion of tumor-feeding vessels after infusion, and further studies are needed to confirm these preliminary results.

Breast-fed infants showed decreased incidence of obesity, hypertension, diabetes mellitus, and coronary heart disease in later life and higher cognitive function. Breast milk is rich in long-chain polyunsaturated fatty acids (LCPUFAs) and brain preferentially accumulates LCPUFAs during the last trimester of pregnancy and the first few months of life. Breast-fed infants showed significantly lower plasma glucose levels and higher percentage of docosahexaenoic acid and total percentages of LCPUFAs in their skeletal muscle biopsies compared with formula fed. LCPUFAs suppress the production of pro-inflammatory cytokines, regulate the function of several neurotransmitters, enhance the number of insulin receptors in the brain and other tissues, and decrease insulin resistance. LCPUFAs may enhance the production of bone morphogenetic proteins (BMPs), which participate in neurogenesis. It is proposed that the beneficial effects of breast feeding in later life can be attributed to its rich LCPUFA content. It is likely that inadequate breast feeding results in marginal deficiency of LCPUFAs during the critical stages of development, which can lead to insulin resistance. Hence, promoting prolonged breast feeding and/or supplementing LCPUFAs during the critical stages of development may be beneficial in preventing insulin resistance., (Copyright 2002 Elsevier Science Ltd.)

It is known that the concentrations of essential fatty acids and their metabolites including eicosanoids, free radicals and anti-oxidants are altered in glomerular disorders. Both corticosteroids and n-3 fatty acids--eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA respectively)--are useful in the management of glomerular disorders. In the present study, the altered plasma concentrations of lipid peroxides, nitric oxide and the metabolites of essential fatty acids and anti-oxidants--superoxide dismutase, glutathione peroxidase and vitamin E--in the RBC membranes of patients with glomerular disorders (nephrotic syndrome) reverted to normalcy following corticosteroids or EPA/DHA administration. This suggests that the beneficial actions of corticosteroids and EPA/DHA in glomerular disorders can be attributed to their action on the pro-oxidant and anti-oxidant concentrations and metabolism of essential fatty acids., (Copyright 2001 Harcourt Publishers Ltd.)

In systemic lupus erythematosus, plasma concentrations of tumor necrosis factor alpha (TNF alpha) and other pro-inflammatory cytokines are elevated and those of transforming growth factor beta (TGF beta) are decreased. TNF alpha prevents lupus nephropathy whereas increased concentration of TGF beta causes glomerulosclerosis. Insulin inhibits TNF alpha and enhances TGF beta production, augments nitric oxide synthesis and blocks superoxide anion generation. Polyunsaturated fatty acids (PUFAs) also have actions similar to insulin. Hence, it is suggested that a combination of insulin (in the form of glucose-insulin-potassium) and PUFAs may be of benefit in lupus and other inflammatory conditions., (Copyright 2001 Harcourt Publishers Ltd.)

Statins and polyunsaturated fatty acids have similar actions: both enhance endothelial nitric oxide synthesis, inhibit the production of pro-inflammatory cytokines, lower cholesterol levels, prevent atherosclerosis and are of benefit in coronary heart disease, stroke and osteoporosis. Statins enhance the conversion of linoleic acid and eicosapentaenoic acid to their long chain derivatives. Animals with essential fatty acid deficiency show an increase in HMG-CoA reductase activity, which reverts to normalcy following topical application of linoleic acid. Similarly to statins, polyunsaturated fatty acids also inhibit HMG-CoA reductase activity. In view of the similarity in their actions and as statins influence essential fatty acid metabolism, it is suggested that essential fatty acids and their metabolites may serve as second messengers of the actions of statins., (Copyright 2001 Harcourt Publishers Ltd.)

Vegetarians are known to have a low incidence of cardiovascular diseases and lower blood pressure compared to non-vegetarians. The exact cause for this is not known. In the present study, it was found that, in general, vegetarians (female > males) have a higher concentrations of anti-oxidant enzymes: catalase and superoxide dismutase in their RBC membranes and lower levels of plasma lipid peroxides compared to non-vegetarians. Both male and female non-vegetarians were found to have a higher n-3/n-6 ratio compared to vegetarians. These results suggest that vegetarians have a higher anti-oxidant status and low levels of n-3 fatty acids. It remains to be seen whether this alterations in the oxidant and anti-oxidant status and n-3 concentrations explains the lower incidence of cardiovascular diseases and lower blood pressure in vegetarians., (Copyright 2001 Harcourt Publishers Ltd.)

Previous studies showed that essential fatty acid (EFA) deficiency, conjugated linoleic acid and troglitazone exert a protective effect in animal models of diabetes mellitus. Here we show that alloxan-induced in vitro cytotoxicity and apoptosis in an insulin secreting rat insulinoma, RIN, cells can be prevented by arachidonic acid (AA) and that both cyclo-oxygenase and lipoxygenase inhibitors do not block this protective action. Alloxan-induced diabetes in male Wistar rats was also prevented by oral supplementation of AA, gamma-linolenic acid (GLA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This protective action is best when the animals were pre-treated with the fatty acid. These results suggest that polyunsaturated fatty acids can prevent alloxan-induced diabetes mellitus in experimental animals and may be useful to prevent diabetes mellitus in the high-risk population., (Copyright 2001 Harcourt Publishers Ltd.)

Low rates of coronary heart disease was found in Greenland Eskimos and Japanese who are exposed to a diet rich in fish oil. Suggested mechanisms for this cardio-protective effect focused on the effects of n-3 fatty acids on eicosanoid metabolism, inflammation, beta oxidation, endothelial dysfunction, cytokine growth factors, and gene expression of adhesion molecules; But, none of these mechanisms could adequately explain the beneficial actions of n-3 fatty acids. One attractive suggestion is a direct cardiac effect of n-3 fatty acids on arrhythmogenesis. N-3 fatty acids can modify Na+ channels by directly binding to the channel proteins and thus, prevent ischemia-induced ventricular fibrillation and sudden cardiac death. Though this is an attractive explanation, there could be other actions as well. N-3 fatty acids can inhibit the synthesis and release of pro-inflammatory cytokines such as tumor necrosis factoralpha (TNFalpha) and interleukin-1 (IL-1) and IL-2 that are released during the early course of ischemic heart disease. These cytokines decrease myocardial contractility and induce myocardial damage, enhance the production of free radicals, which can also suppress myocardial function. Further, n-3 fatty acids can increase parasympathetic tone leading to an increase in heart rate variability and thus, protect the myocardium against ventricular arrhythmias. Increased parasympathetic tone and acetylcholine, the principle vagal neurotransmitter, significantly attenuate the release of TNF, IL-1beta, IL-6 and IL-18. Exercise enhances parasympathetic tone, and the production of anti-inflammatory cytokine IL-10 which may explain the beneficial action of exercise in the prevention of cardiovascular diseases and diabetes mellitus. TNFalpha has neurotoxic actions, where as n-3 fatty acids are potent neuroprotectors and brain is rich in these fatty acids. Based on this, it is suggested that the principle mechanism of cardioprotective and neuroprotective action(s) of n-3 fatty acids can be due to the suppression of TNFalpha and IL synthesis and release, modulation of hypothalamic-pituitary-adrenal anti-inflammatory responses, and an increase in acetylcholine release, the vagal neurotransmitter. Thus, there appears to be a close interaction between the central nervous system, endocrine organs, cytokines, exercise, and dietary n-3 fatty acids. This may explain why these fatty acids could be of benefit in the management of conditions such as septicemia and septic shock, Alzheimer's disease, Parkinson's disease, inflammatory bowel diseases, diabetes mellitus, essential hypertension and atherosclerosis.

Background: Increased dietary intake of polyunsaturated fatty acids (PUFAs) is known to be associated with a decrease in the incidence of peptic ulcer disease possibly due to increase in the synthesis of prostaglandins. But, it is also likely that conversion of PUFAs to PGs may not always be required for gastric mucosal protection. Present study was designed to study the role of PUFAs in pathobiology of steroid induce gastric damage in rats., Methods: Wistar rats were treated with 5 mg/kg bodyweight of dexamethasone to induce gastric mucosal ulcers. Effects of PUFAs was studied by supplementation of Fish oil (rich in n-3 EPA and DHA) and AA rich oil. Famotidine was used as a positive control. Generation of lipid peroxides, nitric oxide and the activity of anti-oxidant enzymes were also studied., Results: Dexamethasone induced ulceration was associated with changes in the phospholipid fatty acid profile, levels of lipid peroxidation products, nitric oxide and activity of anti-oxidant enzymes. The fatty acid profile showed an increase in LA and a decrease in other PUFAs like GLA, AA, EPA and DHA. When PUFAs were supplemented in the form of Fish oil and AA rich oil or when the animals were treated with H2-blocker, famotidine, there was a decrease in the incidence of ulceration in the animals associated with near normalization of changes in the phospholipid fatty acid profile. The levels of lipid peroxides, nitric oxide, and anti-oxidant activity also reverted to control values., Conclusions: Dexamethasone induced gastric ulceration was prevented by PUFAs. This is supported by the results of our earlier study where in it was noted that in patients with DU plasma lipid peroxides, nitric oxide and phospholipid fatty acid pattern and red cell antioxidant activity were altered similar to those seen in dexamethasone treated group of the present study. These abnormalities, similar to the PUFA treated groups of the present study, reverted to normalcy following treatment of the patients with lansoprazole, a proton pump inhibitor. Further, PUFAs are known to inhibit the growth of Helicobacter pylori in vitro. Hence, it is concluded that PUFAs, free radicals, nitric oxide and anti-oxidants play a significant role in the pathobiology of peptic ulcer.

Several studies have shown that the activities of delta-6-desaturase and delta-5-desaturase are depressed in experimental diabetes and in humans with insulin- and non-insulin-dependent diabetes mellitus (type I and type II diabetes mellitus respectively). Furthermore, treatment with insulin is known to correct the defects in desaturases in rats and humans with diabetes, especially in type I. In a recent study, we demonstrated that L-arginine and nitric oxide can prevent alloxan-induced beta cell damage, and the severity of diabetes, and restore the antioxidant status to near normal levels. But, no information is available as to the relationship between L-arginine-nitric oxide system and the metabolism of essential fatty acids in diabetes mellitus. In the present study, it was noted that the plasma levels of saturated fatty acids: stearic and palmitic were increased where as unsaturated fatty acids such as oleic, linoleic, gamma-linolenic and eicosapentaenoic acids (OA, LA, GLA and EPA respectively) were decreased in alloxan-induced diabetic rats. In the liver phospholipid (PL) fraction, GLA, DGLA (dihomo-GLA) and alpha-linolenic acid (ALA) were decreased in the alloxan-treated group; in the muscle PL fraction, LA, GLA and DGLA were low, whereas an increase in the saturated fatty acid content was noted. L-arginine (the precursor of nitric oxide) and sodium nitroprusside (a nitric oxide donor) treatment of alloxan-induced diabetic rats enhanced the levels of LA, GLA and DGLA. Further, nitric oxide synthase inhibitor, L-NMMA, prevented this beneficial action of L-arginine-nitric oxide system on essential fatty acid metabolism. The abnormalities in the essential fatty acid metabolism observed also reverted to normalcy following control of diabetes with insulin. These results indicate that nitric oxide can enhance the activities of delta-6- and delta-5 desaturases, which are depressed in diabetes, and suggests that there is a close interaction between L-arginine-nitric oxide system and the metabolism of essential fatty acids.

Long chain polyunsaturated fatty acids derived from essential fatty acids have been shown to be toxic to Plasmodium falciparum both in vitro and in vivo. Here, we present evidence to suggest that in patients with Plasmodium falciparum malaria the levels of lipid peroxides (a marker of free radical generation) nitric oxide (a potent free radical with immunomodulatory actions), and concentrations of linoleic acid (LA) and alpha-linolenic acid (ALA) are low, whereas those of eicosapentaenoic acid (EPA) are high. The ability of the fatty acids to kill P. falciparum is dependent on their capacity to stimulate free radical generation in neutrophils and macrophages. EPA is more potent than LA in killing the parasite. In view of this, the results of the present study suggest that in patients with P. falciparum malaria the decreased levels of lipid peroxides and nitric oxide may contribute to the persistence of the infection, whereas elevated levels of EPA may be a feeble attempt to overcome this defect.

Essential fatty acids (EFAs) and their metabolites, especially gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid and decosahexaenoic acid are known to induce apoptotic death of tumour cells. But the exact mechanism by which these fatty acids are able to induce apoptosis is not clear. Recent studies suggest that these fatty acids are able to induce apoptosis in cells over expressing cytochrome P450 following depletion of cellular glutathione and inhibition of carnitine palmitoyl transferase I (CPTI) activity. On the other hand, BCL-2 prevented apoptosis induced by these long-chain fatty acids, where as n-3 fatty acids suppressed ras expression leading to suppression of development of overt neoplasia. Phosphorylation of BCL-2 inhibits its ability to interfere with apoptosis and enhances lipid peroxidation leading to the occurrence of apoptosis. Tumour cells treated with long-chain fatty acids show increase in lipid peroxidation process, depletion of antioxidants and phosphorylation of proteins. Based on these results, it is suggested that long-chain fatty acids induce apoptosis by enhancing lipid peroxidation, suppressing BCL-2 expression possibly by phosphorylation and augmentation of P450 activity. Thus, these long-chain fatty acids may, infact act at the level of gene/oncogene expression in producing their cytotoxic action on tumour cells.

It is now believed that the GLUT-4 receptor, tumor necrosis factor-alpha (TNF-alpha), essential fatty acids (EFAs) and their metabolites and daf-genes have an important role in the development of obesity and non-insulin dependent diabetes mellitus (NIDDM). The protein encoded by daf-2 is 35% identical to the human insulin receptor, daf-7 codes a transforming growth factor-beta (TGF-beta) type signal and daf-16 can enhance superoxide dismutase (SOD) expression. EFAs and their metabolites can alter the cell membrane fluidity and enhance the expression of GLUT-4 and insulin receptors. EFAs can suppress TNF-alpha production and secretion, a mechanism that may have relevance to the role of these fatty acids in the pathogenesis of insulin resistance, obesity and NIDDM. Melatonin has anti-oxidant actions similar to daf-16, TGF-beta and SOD. Based on this evidence, it is proposed that GLUT-4, TNF-alpha, EFAs, daf-genes, melatonin and leptin interact with each other in ways which may have relevance to the development or abrogation of insulin resistance, obesity, NIDDM, complications due to NIDDM, longevity and ageing.

Cis-unsaturated fatty acids (c-UFAs) have been shown to be capable of decreasing the survival of macrophage tumor (AK-5) cells in vitro. This cytotoxic action of c-UFAs was found to be associated with an increase in free radical generation and lipid peroxidation process and a simultaneous decrease in cellular anti-oxidants such as superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase, glutathione and vitamin E. In the present study, it was observed that c-UFAs such as gamma linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can activate phospholipase C (PLC) and enhance diacylglycerol formation; all the fatty acids except alpha linolenic acid (ALA) increased the binding of phorbol dibutyrate acetate (PDBu) suggesting translocation of protein kinase C (PKC) and at the same time these fatty acids (especially GLA, AA, EPA and DHA) also enhanced PKC activity. AA, EPA and DHA decreased the activity of protein kinase A (PKA) both in the cytosol and particulate fractions whereas ALA and GLA enhanced the PKA activity in the particulate fractions; all the fatty acids except ALA reduced cyclic AMP levels and an enhanced phosphorylation of about 13 proteins of the nuclear fraction and about eight proteins of the plasma membrane fraction was noted in c-UFA treated AK-5 cells in vitro. These results suggest that c-UFAs can alter the activities of second messenger systems such as diacylglycerol and protein kinases and can phosphorylate both plasma membrane and nuclear proteins which are likely to be components of NADPH oxidase. Based on these results, it is suggested that fatty acids may mediate their cytotoxic action in part by modulating the expression of PKC. Activated PKC may then intensify the pro-oxidant state by augmenting NADPH oxidase, so inducing superoxide anion generation which may ultimately lead to cytolysis.

In patients with duodenal ulcer (DU), the plasma levels of nitrite and lipid peroxides, the anti-oxidant content of red cells and plasma phospholipid fatty acid analysis were performed both before and after healing of the ulcer following treatment with lansoprazole, a proton pump inhibitor. These results showed that during the phase of active DU, the concentrations of antioxidants (superoxide dismutase, SOD, catalase and glutathione peroxidase) in red cells were low where as those of lipid peroxides and nitric oxide were high. Of the fatty acids measured, the concentration of palmitic acid (16:0) was increased during the active ulcer phase whereas those of arachidonic acid, alpha-linolenic acid and docosahexaenoic acid were low. These biochemical abnormalities reverted to normal following healing of the ulcer with lansoprazole. These results coupled with the observation that polyunsaturated fatty acids (PUFAs) can inhibit the growth of Helicobacterpylori and heal the ulcer suggest that free radicals, anti-oxidants, nitric oxide and PUFAs may play a significant role in the pathogenesis of DU. If this is true, it suggests that PUFAs can be exploited as potential anti-peptic ulcer drugs.

The effect of fish oil (FO, given in the form of MaxEPA) rich in n-3 fatty acids and evening primrose oil (EPO) rich in n-6 fatty acids on two-stage skin carcinogenesis in mice was studied. Both FO and EPO inhibited the papilloma formation to a significant degree only during the promotion stage which was associated with an increase in lipid peroxidation. Both FO and EPO inhibited the binding of benzo(a)-pyrene to skin cell DNA suggesting that this could be one of the mechanism(s) by which these oils could be preventing papilloma development. Neither EPO nor FO influenced epidermal cell proliferation. In the FO group, LA (linoleic acid), AA (arachidonic acid) and DHA (docosahexaenoic acid) were increased, whereas in the EPO group a significant increase in the AA content was noted. No specific changes in the fatty acid pattern were observed in any of the groups that could be attributed to the papilloma incidence. These results suggest that FO and EPO can influence papilloma formation which can be attributed, at least in part, to their ability to prevent benzo(a)pyrene binding to DNA and to an increase the lipid peroxidation process.

It is now reasonably well established that Helicobacter pylori is the most likely cause for duodenal ulcer. What is not clear is how this infection is related to the excess acid production, why few people with Helicobacter pylori infection have duodenal ulcer and how diet is related to duodenal ulcer. Here it is suggested that a deficiency of cis-unsaturated fatty acids (otherwise called as polyunsaturated fatty acids, PUFAs) especially gamma-linolenic acid, dihomo-gamma-linolenic acid, arachidonic acid and eicosapentaenoic acid may be responsible for duodenal ulcer. Patients with active duodenal ulcer are known to have low concentrations of these PUFAs in their plasma phospholipid fraction and they revert to normal levels after treatment with H2 blockers. In addition, these PUFAs have the ability to inhibit the growth of Helicobacter pylori, suppress acid production and both in experimental animals and humans these PUFAs could heal the ulcer and protect the gastric mucosa from aspirin and steroid-induced damage. Further, PUFAs have other beneficial actions such as capacity to prevent/arrest atherosclerosis, lower plasma cholesterol and triglyceride levels and cytotoxic action on tumour cells. Since PUFAs can be administered over long periods of time and are relatively non-toxic, it is suggested that PUFAs may be exploited as potential anti-ulcer agents.

In vitro and in vivo studies have shown that gamma-leinolenic acid (GLA) can selectively kill tumour cells without harming normal cells. In view of this we have investigated the effect of intratumoural injection of GLA in intracranial gliomas, after reconfirmation of the safety of the drug on normal dog brain (n = 3). Fourteen patients underwent neurosurgical decompression along with placement of a catheter into the tumour bed. At the end of 1 week following surgery the patients were injected with 1 mg of GLA in sterile saline into the tumour bed daily for 10 days through the reservoir placed in the bone flap. Repeat computed tomography scans were obtained both before and after the GLA therapy with and without contrast administration. Necrosis and regression of the tumour have been observed, with reduction in mass effect and shift of midline structures. Two years' follow-up reveals that GLA is safe and tumour recurrence may be less in treated patients.

Tumour cell drug resistance is a major problem in cancer chemotherapy. Essential fatty acids have been shown to be cytotoxic to a variety of tumour cells in vitro. But, the effect of these fatty acids on tumour cell drug resistance has not been well characterized. Gamma-linolenic acid (GLA) of the n-6 series and eicosapentaenoic acid (EPA) of the n-3 series potentiated the cytotoxicity of anti-cancer drugs: vincristine, cis-platinum and doxorubicin on human cervical carcinoma (HeLa) cells in vitro. Alpha-linolenic acid (ALA), GLA, EPA and docosahexaenoic acid (DHA) enhanced the uptake of vincristine by HeLa cells. In addition, DHA, EPA, GLA and DGLA were found to be cytotoxic to both vincristine-sensitive (KB-3-1) and -resistant (KB-ChR-8-5) human cervical carcinoma cells in vitro. Pre-incubation of vincristine-resistant cells with sub-optimal doses of fatty acids enhanced the cytotoxic action of vincristine. GLA, DGLA, AA, EPA and DHA enhanced the uptake and inhibited the efflux of vincristine and thus, augmented the intracellular concentration of the anti-cancer drug(s). Fatty acid analysis of KB-3-1 and KB-ChR-8-5 cells showed that the latter contained low amounts of ALA, GLA, 22:5 n-3 and DHA in comparison to the vincristine-sensitive cells. The concentrations of GLA and DHA were increased 10-15 fold in the phospholipid, free fatty acid and ether lipid cellular lipid pools of GLA and DHA treated cells. These results coupled with the observation that various fatty acids can alter the activity of cell membrane bound enzymes such as sodium-potassium-ATPase and 5'-nucleotidase, levels of various anti-oxidants, p53 expression and the concentrations of protein kinase C suggest that essential fatty acids and their metabolites can reverse tumour cell drug-resistance at least in vitro.

Both alpha-linolenic (ALA) and eicosapentaenoic acids (EPA) were toxic to SP 2/0 mouse myeloma cells in vitro. On the other hand, linoleic acid (LA), gamma-linolenic acid (GLA), di-homo-gamma linolenic acid (DGLA), arachidonic acid (AA), docosahexaenoic acid (DHA) and oleic acid (OA) were much less effective in their growth suppressive actions. Both nordihydroguaiaretic acid (NDGA) and Indomethacin (IM) could block the action of the fatty acids indicating a role for prostaglandins (PGs) and leukotrienes (LTs) in the growth suppressive action of ALA and EPA. Superoxide dismutase (SOD) completely blocked, while vitamin E and reduced glutathione (GSH) could prevent to a limited extent the anti-proliferative effects of ALA and EPA. Catalase, mannitol, chlorpromazine (CPZ) and trifluoperazine (TFP) did not block the cytotoxic actions of ALA and EPA. N(G)-mono-methyl L-arginine (N(G)MMA), an analogue of L-arginine, which inhibits nitric oxide synthase, was ineffective in preventing the cytotoxicity induced by ALA and EPA. Fatty acid analysis of the various lipid fractions of SP 2/0 cells treated with ALA and EPA showed significant incorporation of these fatty acids in the cell membrane lipid pools. These results suggest that ALA and EPA induced suppression of SP 2/0 cell proliferation is cyclo-oxygenase (CO), lipoxygenase (LO) and superoxide dependent. Lipid peroxidation has only a limited role in this process. Both calmodulin dependent process and L-arginine derived nitric oxide do not seem to have a role in the cytotoxic action of ALA and EPA in these cells.

Eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA respectively) can suppress the production of interleukin-1 (IL-1), IL-2 and TNF (tumor necrosis factor) but not of IL-4 by human lymphocytes in vitro. In addition, the concentrations of EPA and DHA were also found to be low in the plasma phospholipid fraction of patients with SLE. In a limited clinical study performed by us earlier, it was observed that oral supplementation of EPA/DHA to patients with SLE can induce clinical remission without any side-effects. Since oxygen free radicals are known to be involved in the pathobiology of SLE, we estimated the plasma concentrations of lipid peroxides, nitric oxide, and anti-oxidants such as catalase, superoxide dismutase (SOD), glutathione peroxidase and vitamin E in these patients both before and after the induction of remission following EPA/DHA administration. These results showed that the levels of lipid peroxides are elevated and those of nitric oxide, SOD and glutathione peroxidase are decreased in SLE prior to EPA/DHA supplementation. Following EPA/DHA administration the concentrations of lipid peroxides, and those of nitric oxide, SOD and glutathione peroxidase reverted to near normal levels. These results suggest that oxidant stress, nitric oxide, and anti-oxidants play a significant role in SLE and that EPA/DHA can modulate oxidant stress and nitric oxide synthesis and may have a regulator role in the synthesis of anti-oxidant enzymes such as SOD and glutathione peroxidase. From the results of this study, we would like to suggest that measurement of lipid peroxides, nitric oxide and anti-oxidants can be used as markers to predict prognosis in patients with SLE.

The effect of n-3 and n-6 fatty acids (FAs) on the growth of human cervical carcinoma (HeLa) cells was studied. Of all the FAs tested, docosahexaenoic acid (DHA, 22:6 n-3) and eicosapentaenoic acid (EPA, 20:5 n-3) were found to be the most potent in their cytotoxic action on HeLa cells and the potency of various fatty acids with regard to their cytotoxic action was as follows: DHA > EPA > dihomo-gamma-linolenic acid (DGLA) = gamma-linolenic acid (GLA) > linoleic acid (LA) > arachidonic acid (AA) > alpha-linolenic acid (ALA). The cycloxygenase inhibitor indomethacin, the lipoxygenase inhibitor nordihydroguaretic acid (NDGA), the antioxidants vitamin E, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT), the superoxide anion quencher superoxide dismutase (SOD), the hydroxyl and hydrogen peroxide quenchers mannitol and catalase, respectively, and the calmodulin antagonists trifluoperazine (TFP) and chlorpromazine (CPZ) could all block the cytotoxic action of GLA, which was used as a representative cytotoxic FA, on HeLa cells. On the other hand, copper and iron salts and buthionine sulfoxamine, a glutathione (GSH) depletor, potentiated the cytotoxic action of suboptimal doses of GLA. GLA-induced radical generation and lipid peroxidation in HeLa cells could be blocked by indomethacin, NDGA and calmodulin antagonists. The cytotoxic action of cis-unsaturated fatty acids (c-UFAs) is not dependent on the alteration in the protein kinase C levels since no alteration in the diacylglycerol levels was observed. Hydroxy and hydroperoxy products of GLA were found to be toxic to HeLa cells, whereas prostaglandin (PG)E1, PGF2 alpha, and prostacyclin stimulated cell growth. From these results, it is evident that radicals are the modulators of the cytotoxic action of c-UFAs, that their formation is a calmodulin-dependent process, and that lipoxygenase products may mediate the tumoricidal action of FAs.

Mortality and morbidity from coronary heart disease (CHD), diabetes mellitus (DM) and essential hypertension (HTN) are higher in people of South Asian descent than in other groups. There is evidence to believe that essential fatty acids (EFAs) and their metabolites may have a role in the pathobiology of CHD, DM and HTN. Fatty acid analysis of the plasma phospholipid fraction revealed that in CHD the levels of gamma-linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are low, in patients with HTN linoleic acid (LA) and AA are low, and in patients with non-insulin dependent diabetes mellitus (NIDDM) and diabetic nephropathy the levels of dihomo-gamma-linolenic acid (DGLA), AA, alpha-linolenic acid (ALA) and DHA are low, all compared to normal controls. These results are interesting since DGLA, AA and EPA form precursors to prostaglandin E1, (PGE1), prostacyclin (PGI2), and PGI3, which are potent platelet anti-aggregators and vasodilators and can prevent thrombosis and atherosclerosis. Further, the levels of lipid peroxides were found to be high in patients with CHD, HTN, NIDDM and diabetic nephropathy. These results suggest that increased formation of lipid peroxides and an alteration in the metabolism of EFAs are closely associated with CHD, HTN and NIDDM in Indians.(ABSTRACT TRUNCATED AT 250 WORDS)

House lizards are able to regenerate their tails. This is an ideal model to study the growth and differentiation of an organ. Prostaglandins (PGs) are local hormones having diverse and potent biological activities. In an effort to understand PG metabolism during the growth and differentiation of the regenerating lizard tail, we analysed the fatty acid (FA) composition of phospholipids are free FAs by GC, the activity of two rate-limiting enzymes (phospholipases A and C), the activity of the enzyme responsible for the oxygenation of polyunsaturated fatty acids to PGs (cyclooxygenase) and characterized the endogenous PGs by HPLC. It was observed that on the 20th day, i.e. the tissue differentiation period, there was an increase in phospholipase A activity, together with a sudden fall in the free arachidonic acid (AA) level, an increase in cyclooxygenase activity and the appearance of endogenous PGE2. PGE2 can stimulate cyclic adenosine monophosphate (cAMP) production and it may stimulate a cascade of events associated with tissue differentiation.

Systemic lupus erythematosus (SLE) is a chronic inflammatory condition characterised by arthritis, cutaneous rash, vasculitis, and involvement of central nervous system, renal and cardiopulmonary manifestations. Abnormalities in the cytokine network is believed to be involved in the pathobiology of this condition. The n-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can suppress T-cell proliferation and the production of interleukin-1, interleukin-2, and tumor necrosis factor by these cells both in vitro and in vivo. Oral supplementation of EPA and DHA induced prolonged remission of SLE in 10 consecutive patients without any side-effects. These results suggest that n-3 fatty acids, EPA and DHA, are useful in the management of SLE and possibly, other similar collagen vascular diseases.

Cis-unsaturated fatty acids such as dihomogamma-linolenic acid (DGLA), arachidonic acid (AA) and eicosapentaenoic acid (EPA), which form precursors to 1, 2 and 3 series prostaglandins (PGs), have been shown to suppress human T-cell growth in vitro by a prostaglandin E (PGE)-independent mechanism. In an earlier study, we showed that these fatty acids can induce free radical generation in human neutrophils and tumor cells. Here we show that cis-unsaturated fatty acids augment free radical generation and lipid peroxidation in human T-cells. The growth suppressive action of cis-unsaturated fatty acids on human T-cells could be blocked by anti-oxidant, vitamin E and the superoxide anion quencher superoxide dismutase. These results suggest that c-UFAs-induced cell growth suppression is a free radical dependent process.

Cytokines, released by T cells, participate in inflammation and produce tissue injury. Excess production of cytokines such as interleukins (ILs) and tumor necrosis factor (TNF) is believed to be involved in the pathobiology of conditions such as septicemia and septic shock, collagen vascular diseases, glomerulonephritis etc. On the other hand, prostaglandins (PGs) are known to modulate inflammation, immune response, and T-cell response to antigens. But relatively little information is available on the effects of PGs and PG precursors on the release of cytokines. Here the authors present data which suggests that PGs including thromboxane B2 (TXB2) and their precursors such as dihomo-gamma linolenic acid (DGLA), arachidonic acid (AA) and eicosapentaenoic acid (EPA) can inhibit T-cell proliferation and influence their ability to secrete IL-2, IL-4, IL-6 and TNF in vitro. These results may have relevance to the use of PG-precursors in various inflammatory conditions including collagen vascular diseases.

Coronary artery disease (CAD), hypertension and diabetes mellitus are more common in Indians compared to their incidence in the Western population. The exact reason for this is not known. One of the risk factors for the development of and complications due to CAD, hypertension and diabetes mellitus could be hyperinsulinemia and insulin resistance and low plasma levels of arachidonic acid and eicosapentaenoic acid, metabolites of dietary essential fatty acids (EFAs), cis-linoleic and alpha-linolenic acids. Fatty acid analysis of the plasma phospholipid (PL) fraction of normal Indians showed that they have low concentrations of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid in comparison to those seen in Canadian and Minnesota (USA) normals. Since insulin can activate EFA metabolism, this alteration in the EFA metabolism may, at least, in part explain the high incidence of CAD, hypertension and diabetes mellitus and insulin resistance and hyperinsulinemia that are common in Indians.

It is now believed that free radicals and eicosanoids participate in the pathogenesis of immune mediated mesangial cell injury and renal tissue damage including glomerulonephritis. But relatively little information is available about the role of essential fatty acids, (EFAs), the precursors of eicosanoids, in renal diseases. We studied the levels of superoxide anion, hydrogen peroxide, lipid peroxides and the concentrations of various metabolites of EFAs in the plasma phospholipid fraction of patients with glomerular disorders. A significant increase in the production of superoxide anion and hydrogen peroxide both by unstimulated and phorbol-myristate acetate (PMA)-stimulated leukocytes, increase in the plasma lipid peroxide levels and a marked reduction in the levels of arachidonic acid (AA) and eicosapentaenoic acid, the precursors of 2 and 3 series prostaglandins (PGs) respectively, were observed in these patients. Since eicosapentaenoic acid and prostacyclin, which is derived from AA, are believed to be of benefit in the prevention of progression of renal disease, and as free radicals can cause renal dysfunction, our results suggest that free radicals and the metabolites of EFAs play a significant role in the pathogenesis of glomerular disorders.

Prostacyclin (PGI2) prevented genetic damage to the bone marrow cells of mice induced by gamma-radiation, benzo(a)pyrene(BP) and cis-platinum(cis-DDP). Carba-PGI2, an analogue of PGI2, was also effective against cis-DDP-induced mutagenicity. In a time-course study it was observed that the geno-protective action of PGI2, can last as long as 24 hr. 6-keto-PGF1 alpha, a major metabolite of PGI2 and c-AMP, a second messenger, were ineffective in bringing about this beneficial action. PGI2 did not influence free radical generation induced by phorbol myristate acetate in human peripheral leukocytes. This suggests that the genoprotective action of PGI2 is not mediated by its metabolite 6-keto-PGF1 alpha and the second messenger cyclic-AMP and is not due to any action on free radical generation. This geno-protective action of PGI2 would be futile if it interfered with the tumoricidal action of cis-DDP. It was observed that the cytotoxic action of cis-DDP against Meth-A tumor cells was not interfered with by PGI2 and carba-PGI2 both in vitro and in vivo. This description of the geno-protective action of PGI2 is important in the development of new strategies in cancer chemotherapy since, it is likely that anticancer drugs, at least cis-DDP can be given along with PGI2 to prevent genetic damage to normal cells without interfering with their tumoricidal action.

We studied fatty acid changes that are likely to occur during phorbolmyristate acetate (PMA)-induced differentiation of HL-60 cells. It was observed that PMA-induced differentiation is associated with increased uptake, but not synthesis, of fatty acids. Fatty acid analysis revealed that arachidonic acid (AA), 20:5 n-3 and 22:6 n-3 levels are reduced with a concomitant increase in 22:5 n-6 in the phospholipid fraction. In the FFA fraction there are increases in free AA, free 20:5 n-3, 22:5 n-3 and 22:6 n-3, and a fall in free 22:5 n-6 in PMA-treated cells. PMA-induced differentiation and nitroblue tetrazolium reduction by PMA-treated cells was only partially inhibited (about 20-30%) by indomethacin and nordihydroguiaretic acid (cyclooxygenase and lipoxygenase inhibitors respectively), but not by superoxide dismutase, catalase or mannitol. These results indicate that PMA-induced differentiation of HL-60 cells is accompanied by specific changes in the fatty acid composition of the cells.

In vitro and in vivo studies have shown that gamma-linoleic acid (GLA), arachidonic acid (AA) and eicosapentaenoic acid (EPA) can selectively kill tumor cells. In a clinical trial, the effectiveness of intratumoral administration of GLA in patients with gliomas was studied. Of the 6 patients treated, all showed substantial response to GLA as documented by computerized tomography. There were no acute side-effects due to the therapy. This report demonstrates that intratumoral administration of GLA is a possible approach to the treatment of human glial tumors.

Eicosanoids, lymphokines, and free radicals are known to participate in the pathogenesis of inflammation. Tumour necrosis factor (TNF), interleukin-1 and 6 (IL-1 and IL-6) and colony stimulating factor -1 (CSF-1) are secreted mainly by activated macrophages, whereas T-cells secrete IL-2, IL-3, IL-4 and interferon-gamma (IFN-gamma). In addition, activated macrophages and lymphocytes can also produce eicosanoids and free radicals which have potent pro-inflammatory actions. Eicosanoids, lymphokines, and free radicals can modulate the immune response, cell proliferation, stimulate collagenase and proteases secretion and induce bone resorption; events which are known to be associated with various collagen vascular diseases. On the other hand transforming growth factor-beta (TGF-beta) produced by synovial tissue, platelets and lymphocytes can inhibit collagenase production, suppress T-cell and NK-cell proliferation and activation and block free radical generation and seems to be of benefit in rheumatoid arthritis. Drugs such as cyclosporine, 1,25,dihydroxycholecalciferol and pentoxyfylline can block lymphokine and TNF production and thus, may inhibit the inflammatory process. Essential fatty acids, the precursors of eicosanoids, are suppressors of T-cell proliferation, IL-1, IL-2 and TNF production and have been shown to be of benefit in rheumatoid arthritis, systemic lupus erythematosus and glomerulonephritis. Thus, the interactions between essential fatty acids, eicosanoids, lymphokines, TGF-beta and free radicals suggest that new therapeutic strategies can be devised to modify the course of collagen vascular diseases.

We studied free radical generation, lipid peroxidation and the levels of essential fatty acids and of their metabolites in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Both superoxide and hydrogen peroxide generation by peripheral leukocytes but not malondialdehyde levels, as measured by thiobarbituric acid assay, were found to be significantly enhanced both in RA and SLE. Fatty acid analysis of the plasma PL fraction revealed that both LA and ALA metabolites are significantly decreased in RA and SLE compared to controls. These results suggest that essential fatty acid metabolism is altered in RA and SLE.

Phorbolmyristate acetate or 12-O-tetradecanyl phorbol 13-acetate (PMA or TPA) stimulates membrane phospholipases (phospholipase C or A2) resulting in the formation of diacylglyceride, free arachidonic acid, and increased amounts of arachidonic acid metabolites. Both PMA and AA are stimulators of the respiratory burst in phagocytic cells, induce inflammation, cause chromosomal aberrations, have anti-viral activity and activate protein kinase C. The initial action of PMA is on the cell membrane and is concentrated largely in the lipid phase of cell membranes. This evidence suggests that the actions of PMA are in large part mediated by AA, released from the cell membrane lipid pool. Thus, it is likely that the ability of PMA to induce terminal differentiation in HL-60 cells and to suppress C-myc mRNA levels are also mediated by AA and/or its products. This may have relevance to the possible role of AA in the regulation of oncogenes and cancer.

Infections due to gram-negative bacteria and other organisms can lead to septicemia and shock in some patients. Endotoxins, which cause these pathophysiological events, stimulate macrophages to elaborate tumor necrosis factor and other lymphokines. These lymphokines can augment free radical generation by polymorphonuclear leukocytes, macrophages and other cells, which may ultimately produce respiratory distress syndrome, multiorgan failure and irreversible shock seen in septicemia. This is supported by our results presented here that there is indeed an increase in free radical generation and lipid peroxidation in patients with septicemia. In addition, analysis of plasma lipid profile in these patients showed that gamma-linolenic, dihomogamma-linolenic and arachidonic acids of n-6 series and alpha-linolenic and eicosapentaenoic acids of the n-3 series are decreased in their plasma phospholipid fraction. These results suggest that free radicals, lipid peroxides, and alteration in essential fatty acid metabolism may have a role in the pathogenesis of septicemia.