The roles of eicosanoids in experimental glomerulonephritis

There is accumulating evidence showing alterations of renal eicosanoid synthesis in glomerular disease. Despite the complexity of their role in glomerulonephritis, these compounds appear to play a major part in the inflammatory response and in control of renal hemodynamics. The role of eicosanoids in the filtration of macromolecules has not been established, but there is indirect evidence of their involvement in mediating proteinuria. Dietary manipulation, either by high EPA, high linoleic acid, or EFA-deficient diet, in experimental glomerulonephritis have shown promising results as summarized in Table 1. The therapeutic potential of alterations in dietary fatty acid to modulate the inflammatory response appears to be of great value. Table 2 summarizes the effects of different dietary fatty acid alterations on eicosanoid synthesis. Nonetheless, we should point out that most of the studies of alterations in dietary fatty acids did not document changes in glomerular synthesis of prostaglandin, thromboxane, or HETES. Further studies examining the effects of different fatty acid regimens on glomerular eicosanoid synthesis and the role of these eicosanoids in the development of glomerulonephritis will provide valuable information. These findings could determine the specific type of dietary manipulation to inhibit or stimulate the production of selected eicosanoids.

Immune complex effects on glomerular eicosanoid production and renal hemodynamics

We examined the effect of glomerular immune complex (IC) deposition on glomerular eicosanoid synthesis and the role of the eicosanoids in glomerular pathophysiology. Rats received daily 10 mg i.v. injections of native bovine gamma-globulin (NBGG) or cationic bovine gamma-globulin (CBGG) for 21 days; age-matched controls were maintained. Immunofluorescence and electron microscopy showed mesangial deposits of IC in the NBGG group and capillary wall deposits in the CBGG group, without light or electron microscopic evidence of leukocyte infiltration. One week after the last antigen dose, GFR was similar in all three groups, but RPF increased in the rats given CBGG; (8.37 +/- 0.90 vs. control 5.54 +/- 0.56 ml/min, P less than 0.05). Glomerular synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) was normal in animals that received NBGG. Rats given CBGG had increased glomerular production of PGE2, (2.23 +/- 0.37 vs. control 1.03 +/- 0.16 ng/mg glomerular dry wt, P less than 0.05) and TxB2 (3.12 +/- 0.50 vs. control 0.48 +/- 0.07 ng/mg glomerular dry wt, P less than 0.001). Proteinuria only developed in the rats given CBGG, 86.6 +/- 18 mg/24 hr, which correlated with glomerular TxA2 synthesis, r = 0.82, P = 0.01. Acute administration of the TxA2 synthesis inhibitor, UK-38,485, and a TxA2 receptor antagonist, EP-092, to rats given CBGG did not affect GFR or RPF. The cyclo-oxygenase inhibitor, indomethacin, reduced both GFR and RPF by up to 40% in CBGG-immunized rats. Oral administration of UK-38,485 for six days to nephrotic rats did not result in a statistically significant reduction of proteinuria despite 85% inhibition of glomerular TxB2. We conclude that cationic antigen induces a glomerular disease pathologically similar to membranous nephropathy. The increment of RPF is most probably due to increased glomerular PGE2. The increased TxA2 has no effect on glomerular hemodynamics and probably is not a component in the pathogenesis of proteinuria.

Eicosanoids in experimental and human renal disease

The renal prostaglandins and thromboxanes are powerful autacoids with potential effects on renal hemodynamics, salt and water metabolism, and the immune system. The possibility of adverse effects on renal function in certain patients with renal disease due to cyclooxygenase inhibition with nonsteroidal anti-inflammatory drugs has long been appreciated. Experimental evidence indicates that renal prostaglandin and thromboxane production is increased in several models of renal disease and that similar decrements in renal function occur with cyclooxygenase inhibition and may be due to inhibition of vasodilator prostaglandins. Additionally, several investigators have shown that administration of prostaglandins may be therapeutic in some forms of renal disease, particularly immunologically mediated diseases. Dietary modification to affect prostaglandin production has also been promising in certain experimental models. In contrast to vasodilator prostaglandins, thromboxane is a potent vasoconstrictor and would be expected to have adverse effects on renal function. Despite demonstration of elevated glomerular thromboxane, studies using inhibitors of thromboxane synthesis in immunologically mediated glomerular disease have been disappointing. There is some evidence, however, that these drugs may be of benefit in ureteric obstruction and renal transplant rejection.

Glomerular arachidonate lipoxygenation in rat nephrotoxic serum nephritis

Arachidonate lipoxygenation to monohydroxylated eicosatetraenoic acids (HETE) was studied in rat nephrotoxic serum nephritis (NSN). A single infusion of nephrotoxic serum enhanced conversion of [3H]arachidonic acid ([3H]C20:4) to [3H]12-HETE in glomeruli isolated from nephritic rats compared with controls. The percent conversion of [3H]arachidonic acid was 1.95 +/- 0.2% in control glomeruli and 14.2 +/- 2% in nephritic glomeruli 2 d after induction of disease. No significant changes in the conversion of [3H]C20:4 to [3H]5-, 8-, and 9-HETE were noted. Extraction of glomerular HETE by alkaline hydrolysis, to evaluate possible reacylation of HETE after their production, confirmed the presence of 12-HETE and did not provide evidence of 5-HETE synthesis. Increased glomerular 12-HETE synthesis in nephritic rats was also demonstrated by high pressure liquid chromatography-UV detection and by 12-HETE radioimmunoassay. The enhanced glomerular 12-HETE synthesis commenced as early as 3-5 h after administration of nephrotoxic serum and peaked at day 2 with 10-fold enhancement of 12-HETE production. Increments of glomerular 12-HETE persisted on day 7 and returned toward control levels by day 14. Platelet depletion, induced by antiplatelet antisera, did not decrease glomerular 12-HETE synthesis in NSN, thereby eliminating platelets as the cellular origin of 12-HETE. Glomerular epithelial and mesangial cells are the most likely sources of enhanced 12-lipoxygenase activity. The enhanced arachidonate 12-lipoxygenation in glomerular immune injury could have important proinflammatory effects in the evolution of glomerulonephritis since 12-HETE has important effects on leukocyte function.

Second generation alpha-enones from a pyranosidic alpha-enone

The Diels-Alder product from the reaction of methyl 2,3,6-trideoxy-alpha-D-glycero-hex-2-enopyranosid-4-ulose (1b) with trans-1-methoxy-3-tert-butyl-dimethylsilyloxy-1,3-butadiene is 3b (93%). Reaction of 3b wih sodium borohydride causes reduction of the C-4 carbonyl group only, but, with lithium aluminum hydride, further reactions occur which can be rationalized by fragmentation brought about by hydride cleavage on the silicon-oxygen bond, with simultaneous ejection of the beta-methoxyl group complexed to a trivalent aluminum species. The enone resulting from this fragmentation also reacts further with lithium aluminum hydride, and several products result. The behavior of postulated intermediates, which have been prepared separately and subjected to the reaction conditions, supports the proposed reaction mechanisms. The "second generation" enone (methyl 2,3,6-trideoxy-alpha-D-talopyranosido)-[3,2-d]-2-cyclohexenone+ ++ (10a), arising from the first generation precursors 1b, has been prepare by two routes.

Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. I. Cation transport and sodium-potassium-dependent ATPase

Changes in the cation balance cause hydration and initiate the process of lens opacification. Such alterations were studied in human cataractous lenses and during the development of alloxan-induced diabetic cataract in rats by biochemical and histochemical techniques. The development of alloxan-induced cataract in rats was examined in vivo which showed cortical opacities beginning after 32 days. These opacities did progress to maturity after 64 days and finally the lenses were completely opacified after 96 days of alloxan treatment. The histochemical localization of sodium-potassium-activated adenosine triphosphatase using three different methods provided information on the possible role of this enzyme in normal and cataractous lenses. In human cataractous lenses, sodium-potassium adenosine triphosphatase activity was found to be considerably decreased, whereas no activity of this enzyme was localized in human diabetic cataractous lenses. An animal model provided evidence that an apparent decrease of sodium-potassium adenosine triphosphatase may be involved in the initiation of alloxan-induced diabetic cataract in rats.

Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. II. Histochemical evaluation of lenticular enzymes

The effect of cataractogenesis on the behavior of some enzymes involved in glucose metabolism was examined histochemically both in human lenses and in rat lenses from rats with alloxan-induced diabetes. Several modifications in the currently available techniques were made in order to localize glucose-6-phosphate dehydrogenase, aldose reductase, sorbitol dehydrogenase, hexokinase and ketohexokinase in ocular lens. Human cataractous lenses showed a precipitous drop in glucose-6-phosphate dehydrogenase activity, whereas the lenticular tissues of alloxan-treated rats showed a gradual decrease of this enzyme with the prolongation of diabetes. Aldose reductase activity increased in hypermature and senile diabetic cataracts, whereas sorbitol dehydrogenase activity decreased in these lenses. Similarly, in alloxan-diabetic rat lenses the activity of aldose reductase increased while that of sorbitol dehydrogenase decreased with the prolongation of diabetes. Attempts were made to localize hexokinase and ketohexokinase in ocular lens.

Mechanism of contamination from agricultural chemicals in mammals

Chemicals in the form of pharmaceuticals are used to extend the life of man. It is ironic that other chemicals are also required to poison the pests that compete for the food supply so that man will have enough to eat during his extended lifetime. Now these poisons are reaching levels in the environment where the life span of man is again being shortened by both immediate and long-term effects caused by these pesticides. Hundreds of thousands of people are incapacitated and killed by insecticide poisoning each year, many of them in developing countries, from the chemicals no longer allowed for use in the western nations that produce them. Continuous monitoring and surveillance are required to avoid misuse of pesticides, because many of the hazards associated with these chemicals can be reduced substantially, if not eliminated completely.

Trace elements in serum from Pakistani patients with acute and chronic ischemic heart disease and hypertension

We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.

Partial purification and characterization of lenticular S-adenosylmethionine synthetase

Lenticular S-adenosylmethionine synthetase has been partially purified and characterized. Lower levels of S-adenosylmethionine synthetase were detected by a sensitive radioactive assay procedure in the lenticular extract obtained from the pooled lenses of alloxan-treated rats 96 days of age as compared to the nontreated controls. With respect to chromatographic behavior and kinetic analysis, lenticular S-adenosylmethionine synthetase closely resembled that of the corresponding liver enzyme.

Studies on synergism between glucose and amino acids with respect to insulin release in vitro

The mutual enhancement of the effect of insulin release by glucose and amino acids is not clearly understood. Present in vitro studies with isolated rat islets were undertaken to elaborate the role of amino acids on insulin release, particularly their interaction with glucose as well as among each other, which has been reported to lead to synergism in the human subjects. In the presence of 8.3 mM glucose, both arginine, as well as, leucine potentiated the effect of glucose which increased progressively with the increasing concentrations of the amino acid. This effect of arginine was not synergistic in nature because arginine did not stimulate insulin release in the absence of glucose. The effect of glucose and leucine was found to be additive and not synergistic. No synergism was exhibited by any of the amino acid pairs tested in the present study. Thus both phenylalanine and lysine did not potentiate the effect of either arginine or leucine. Arginine showed a mild, but significant potentiating effect on leucine-stimulated insulin release. It is suggested that synergism between glucose and amino acids and between certain amino acid pairs reported in man may not be due to the direct effects of these stimuli on the beta cells, but some other factors in vivo may be involved.

Radiologic findings of bilharzial (schistosomal) contracted bladder

The radiologic findings in bilharzial contracted bladder are presented. Calcifications of the bladder were seen in only 4.3 per cent, hydronephrosis in 37.2 per cent, and reflux in 62.8 per cent.

Studies on blood saccharoid fraction in normal and diabetic subjects

The exact nature of the saccharoid fraction (non-glucose reducing substances) in human blood is not known. The saccharoid fraction is increased in diabetic patients and a direct relationship exists to the height of the blood sugar. Some of the constituents of the saccharoid fraction, namely, glutathione, glucuronic acid and organic phosphate are significantly increased in diabetic patients. Fructose diphosphate and ATP are increased in the patients treated with oral hypoglycemic drugs. The known constituents of the saccharoid fraction which were determined accounted only for about 48% in normal and 36% in diabetic patients. The reduced contribution of these compounds to the saccharoid fraction in diabetic patients indicates that the nature of the saccharoid fraction may be different in diabetic patients.

Adhesion of cholera phage to glass surfaces at high inactivation temperatures

Decimal dilutions of cholera phage heated in test tubes at the temperature range of 65 degrees to 70 degrees showed an erratic behaviour in that the residual counts had no relationship to the quantity of phage originally present in the tubes. If the contents of the heated tubes were decanted off and the empty tubes washed repeatedly with broth, the recovery of phage from successive washings of the tubes was much higher than what would be expected on the basis of the simple dilution effect of washings. The data presented indicate that the heating causes loose adhesion of phage to the wall of the glass tubes from where they can be detached by washing or shaking. The facts that E. coli phage T1 and also cholera phages tested with two different broths have given similar results, suggest that some general property of the phage itself is responsible for the phenomenon observed. The phenomenon appears to be different from the adsorption of phage to glass filters at lower temperature range described by earlier workers.

Effects of undernutrition and protein malnutrition on brain chemistry of rats

The present study was undertaken to assess the effects of different degrees of nutritional restrictions during fetal life, suckling, and after weaning on the chemical composition of the brain. At 42 days of age, the rats were killed, and the brains were processed for analyses. The rats exposed to severe protein malnutrition after weaning had lower brain weights than those on controls. The brain seems to be resistant to the effects of moderate protein malnutrition imposed during suckling or after weaning. Thus, the brain is either resistant to the effects of mild nutritional deficiency imposed during suckling, or brain composition is very responsive to nutritional rehabilitation initiated after weaning. The effects of severe undernutrition during suckling were not, however, reversed when adequate nutrition was initiated after weaning. The suckling period seems to be critical during development, as the process of myelination was lowered and the levels of electrolytes were irreversibly disturbed. The brains of the rats born to the mothers protein malnourished during gestation were not significantly different from those of controls. The brain seems to be either preferentially protected from the effects of malnutrition imposed during fetal development, or the brain component are very responsive to nutritional rehabilitation initiated immediately after birth. It is suggested that the mother's nutritional status during gestation does not significantly affect the development of the brain. When the young were born to and nursed by protein-malnourished mothers, the growth and the maturation of the brain in such animals were similar to those in rats moderately undernourished during suckling. Growth and maturation of the brain are affected by a lowered level of protein in the diet. Moderate undernutrition imposed during suckling is not important, but the effect is maximum when undernutrition is severe during this period. The suckling period is therefore, comparatively more critical during development.

Effect of iron deficiency anemia on the development of atherosclerosis in chicks

The effect of iron deficiency anemia on the development of atherosclerosis was investigated in chicks. The control group of birds were fed a basal diet, the atherosclerosis group received 1% cholesterol. The lipid content of the aortas of the chicks in atherosclerosis and atherosclerosis-anemia group also developed anemia of appreciable severity in 12 weeks. Hemoglobin and PCV were taken as the index of anemia, while the lipid constituents were determined in plasma and aortic tissue for atherosclerosis. Hypercholesterolemia of almost equal severity occurred in both atherosclerosis and atherosclerosis-anemia groups. The abnormal rise of cholesterol and other lipid material in the aortas of the atherosclerosis and atherosclerosis-anemia groups of birds indicates that iron deficiency anemia did not markedly affect the development of atheroslcerosis; it did not offer any protection in chickens and, in fact, a slight potentiating effect was observed.