Protective effect of myristic acid on renal necrosis occurring in rats fed a methyl-deficient diet.

Weanling rats fed a methyl-deficient diet develop acute renal failure, the morphological features of which vary from focal tubular necrosis to widespread cortical necrosis. We and others have shown that coconut oil, rich in saturated fatty acids, has a renal protective effect in this experimental model. In the experiment we are reporting now, we studied which fatty acid is involved in the protection afforded by coconut oil by feeding five groups of methyl-deficient rats a mixture of corn oil and hydrogenated vegetable oil, C6-C8-C10 fatty acids, C12 fatty acid, C14 fatty acid and C16-C18 fatty acids. Five groups of rats receiving the same diets supplemented with choline chloride were used as controls. The group of methyl-deficient rats fed C14 fatty acid (myristic acid) showed a greater percentage of surviving animals and lower renal damage than the other groups of methyl-deficient rats, indicating that the protective effect of coconut oil found in previous experiments is due to its high content of myristic acid.

Role of kinins in the renoprotective effect of angiotensin-converting enzyme inhibitors in experimental chronic renal failure.

The aim of this study was to investigate whether the renoprotective effect of angiotensin-converting enzyme inhibitors (ACEIs) following 5/6 renal mass reduction is due in part to the potentiation of kinins. Three groups of rats with 5/6 renal mass reduction were studied during the 14 weeks following surgery. One group received no therapy (control); the second group was treated from the beginning with the ACEI ramipril (1 mg/kg/day) added to the drinking water, and the last group received ramipril plus a beta2-bradykinin antagonist, HOE 140 (500 microg/kg/day) via osmotic minipumps. Plasma creatinine did not change in any group during the study. Urinary protein excretion rose in the controls from 9.18+/-1.6 to 45.0+/-5.6 mg/24 h at the end of the study. In ramipril group proteinuria was prevented (initial 7.5+/-1.0 and final 8.6+/-0.8 mg/24h). The effect of ramipril was abolished by HOE 140 (initial 11.6+/-2.0 and final 38.9+/-11 mg/ 24 h). The systolic blood pressure of the controls increased from 106+/-2 to 144+/-5 mm Hg at the 14th week. Ramipril abolished the increase in systolic blood pressure. The effect of ramipril was reverted by HOE 140 (initial 108+/-2 and final 140+/-9 mmHg). Control rats had more severe histopathologic changes. Those animals receiving ramipril + HOE 140 displayed less severe glomerular changes, while rats treated only with ramipril had mild alterations. Thus the glomerular injury score was 2.11+/-0.32 for controls, 1.53+/-0.52 for rats treated with ramipril + HOE 140, and 0.06+/-0.04 for rats treated only with ramipril. The glomerular area was 20,886+/-1,410, 19,693+/-2,200 and 14,352+/-3,200 microm2, respectively, for the 3 groups. These results suggest that the protective effect of ACEIs in the development of chronic renal failure is partially mediated by kinins.

The pigment of melanosis coli: a lectin histochemical study.

BACKGROUND: The compositional nature of the pigment of melanosis coli is essentially unknown. Previous histochemical studies suggested that this pigment has certain similarities with lipofuscin (i.e., age-dependent pigment) and ceroids (i.e., pathologically derived pigments) and that it may contain, therefore, polymerized glycolipids and glycoproteins. However, the saccharide composition of this pigment was never explored by lectin histochemical procedures, which was the main object of this study. METHODS: Colonoscopic biopsy specimens from eight patients with melanosis coli and from three normal control subjects were studied by fluorescent microscopy and by standard and lectin histochemistry. The number of apoptoses in the lining colonic epithelium was also evaluated histologically. RESULTS: Apoptotic bodies were significantly more numerous in patients with melanosis coil than in control subjects. The pigment that accumulates in macrophages of the lamina propia showed autofluorescence, sudanophilia, acid-fastness, and positiveness to PAS and Schmorl's reactions, all of which are common to lipofuscin and ceroids, plus an intense argentaffin reaction abolished by bleaching, indicative of a melanic substance. Lectin histochemistry showed, in decreasing order of frequency, the presence of alpha-D-mannose, sialic acid, beta-D-galactose (lactose), gal-beta-(1-3)acetyl-galactosamine, alpha-D-galactose, and alpha-L-fucose, but no terminal alpha-D-acetyl-galactosaminyl residues. CONCLUSIONS: The significant increase of apoptotic bodies in the lining colonic epithelium indicated that this type of cell death is not due to the natural programmed cell renewal, but to the action of laxatives. Because the autofluorescent pigment of melanosis coli contains melanin (as well as glycoconjugates) and is not dependent on age but on the use of anthranoid laxatives, it should be categorized as a "melanized ceroid." The lectin affinities of this pigment indicated that it contains a substantial number of saccharide residues almost similar to those found in the ceroid pigment of human aortic atheromas. These findings and considerations on the metabolism and pharmacokinetics of anthranoids suggested that the apoptotic epithelial cells, rather than the laxatives, may be the source of the pigment saccharides, whereas the precursors of the melanic substance may be derived from the anthranoids.

Chemiluminescence and antioxidant levels during peroxisome proliferation by fenofibrate.

Fenofibrate, the hypolipidemic drug and peroxisome proliferator, was given to mice (0.23% w/w in the diet) during 1-3 weeks and H2O2 and TBARS steady state concentrations, liver chemiluminescence and antioxidant levels were measured. Administration of fenofibrate during 2 weeks induced an increase of 89% in H2O2 steady state concentration. Spontaneous chemiluminescence was decreased by 57% during fenofibrate treatment, while no significant effect was observed on TBARS concentration. Hydroperoxide-initiated chemiluminescence was decreased by 56% after 15 days of fenofibrate treatment, probably due to an increase in endogenous antioxidant levels. Total and oxidized glutathione increased gradually after fenofibrate administration, obtaining maximal increases of 67% and 58% respectively, after 22 days of treatment. An increase of 55% was found in ubiquinol levels in treated mice, as compared with the controls. alpha-tocopherol content was decreased by 51% in the liver of fenofibrate-treated mice. According to our findings, the high rate of H2O2 production associated with peroxisome proliferation, would not lead to an increase in lipid peroxidation. This can be explained by the presence of high levels of ubiquinols, which act as an antioxidant. The increased production of H2O2, would lead to DNA damage directly, and not through lipid peroxidation processes.

[Collagen nephritis]. / Nefritis colágena.

Fibrillar collagen in the glomeruli is considered specific of the nail-patella syndrome. A new nephropathy with diffuse intraglomerular deposition of type III collagen without nail and skeletal abnormalities has been described. We report the case of a 26-year-old woman who presented persistent proteinuria, hematuria, deafness without nail and skeletal abnormalities. The renal biopsy showed focal and segmental glomerulosclerosis by light microscopy. The electron microscopy revealed the presence of massive fibrillar collagen within the mesangial matriz and the basement membrane. This is the first patient reported in our country. We emphasize the usefulness of electron microscopy in the study of glomerular diseases.

Protective effect of coconut oil on renal necrosis occurring in rats fed a methyl-deficient diet.

Weanling rats fed a methyl-deficient diet develop renal necrosis with acute renal failure. The aim of this experiment was to explore further the role of coconut oil in this experimental model. Weanling Wistar male rats were fed methyl-deficient and their controls were fed methyl-supplemented diets. Coconut oil was fed at 14% and 20%, the latter concentration with and without 1% safflower oil (rich in linoleic acid); other groups received similar diets but instead of coconut oil, a mixture of hydrogenated vegetable oil and corn oil (rich in unsaturated fatty acids) was employed. Coconut oil fed at a 14% concentration did not evidence any protective outcome in relation to the renal lesions. Coconut oil at a 20% concentration showed a protective effect, mainly when the diet included safflower oil. The renal protective effect was evidenced by less or no mortality and increased survival time in the methyl-deficient rats receiving coconut oil, as well as by a reduced incidence (%) and severity of the renal lesions as evaluated by renal weight, and type (tubular and cortical necrosis or repair) and extent (grade) of the renal damage. The lack of a protective outcome when coconut oil was fed at 14%, along with the fact that in those rats receiving coconut oil at 20% the protection was greater when the diet was supplemented with 1% safflower oil, indicates that the protective effect should be attributed to the type of fatty acids coconut oil has and not to their shortage of essential fatty acids.

Lectin histochemistry of lipofuscin and certain ceroid pigments.

Little is known at present about the saccharide components of lipofuscin (age pigment) and ceroid pigments in situ. The purpose of this study was, therefore, to study in detail the lectin reactivities of lipofuscin in neurons and cardiac myocytes of old humans and rats. In addition, those of diverse ceroid pigments found in human aortic atheromas, in the livers of choline-deficient rats, in the uteri of vitamin E-deficient rats and in the crushed epididymal fat pad of rats, are included. Cryostat and deparaffinized sections from all these tissues were either extracted with a solvent mixture of chloroform-methanol-water (10:10:3, v/v) and incubated with 7 different biotinylated lectins or left untreated. Delipidation was done in order to study whether it was possible to discriminate between the saccharide moieties of glycolipids and glycoproteins of lipofuscin and ceroid pigments in situ. Other similarly treated sections were used to study the autofluorescence, sudanophilia, acid-fastness and reactivity to PAS. The frequency and intensity of lectin binding and standard histochemical properties of all the pigments were evaluated semi-quantitatively and blind. The results indicated that mannose was in general the most consistently detected sugar residue in lipofuscin granules of humans and rats, and that this pigment may also contain acetylglucosamine, acetylgalactosamine, sialic acid, galactose and fucose. However, notable differences were found not only in the lipofuscin saccharide components of different cell types of humans and rats, but also in those in the same type of cells in both species. Although mannose was not detected in the hepatic ceroid of choline-deficient rats, this saccharide moiety was almost always present in the other ceroid pigments. Each of the ceroids also contained other types of saccharides although the frequency of the latter varied between different ceroid pigments. While lipofuscin and each of the ceroid pigments showed somewhat different lectin binding patterns, the variability in the frequency of reactivity to lectins suggests that these patterns may not be permanent but transient. In this sense, it appears that lectin histochemistry may not allow these pigments to be differentiated. Furthermore, the extractive procedures used in this study did not enable us to determine whether the saccharides detected in the pigments in situ corresponded to glycolipids or glycoproteins.

Changes in cathepsin B and lipofuscin during development and aging in rat brain and heart.

While results with inhibitors of thiol proteases have led to the suggestion that the progressive increase with age of lipofuscin in post-mitotic and some stable cells may be due to an age-related decline in the activity of these enzymes (Ivy et al., 1989), no direct evidence has been yet presented to support this hypothesis. In this study Wistar female rats were killed at age of 5, 14, and 24 months and the amounts of lipofuscin were histologically quantitated in neurons of the left cerebral parietal cortex and in cardiac myocytes of left ventricle. The sites of cathepsin B activity histochemically detected were quantitated in sections from left cerebral parietal cortex and left ventricle, and the activity of this enzyme was also measured biochemically in brain and heart homogenates. In line with previous findings, the amounts of lipofuscin in neurons and cardiac myocytes increased linearly during development and aging (from 5 to 14 and from 14 to 24 mo.). The sites of cathepsin B activity histochemically detected in sections from cerebral cortex significantly increased from 5 to 14 mo., but remained unchanged from 14 to 24 mo, while in sections from the left cardiac ventricle these sites of activity remained unchanged during development, and significantly increased during aging. On the other hand the biochemically determined activities of cathepsin B in brain and heart homogenates remained unchanged from 5 to 14 mo., but significantly decreased from 14 to 24 mo. These results suggest that the increase in lipofuscin with age may not be due to an age-wise decline in cathepsin B activity.

Effects of lovastatin and leupeptin on ceroidogenesis of vitamin E-deficient and -supplemented young rats.

Previous studies in young normal rats have shown that intracerebral administration of the proteinase inhibitor, leupeptin, caused a rapid accumulation of lipofuscin-like pigment in lysosomes of brain cells (Ivy et al., 1984a). On the other hand, we have recently found that the administration of lovastatin, an inhibitor of HMG-CoA reductase, reduced the ceroid-like pigment and dolichol contents in the crushed epididymal fat pad of rats (Porta et al., 1988). In order to study now the possible modulating effects of these enzyme inhibitors on ceroidogenesis associated with vitamin E deficiency, two main groups of weanling Wistar female rats were respectively fed ad libitum a vitamin E-deficient basal diet, or the same diet supplemented with 16 mg% of dl-alpha-tocopherol acetate. The vitamin E-deficient and -supplemented rats were further subdivided and received for 8 weeks their diets alone or with 2, 1, or 0.5 g of lovastatin/kg of diet. Other subgroups were treated with constant peritoneal infusion of 0.5 mg/day of leupeptin by means of osmotic minipumps (Alzet 2002) consecutively implanted at days 15, 30, and 45. Lovastatin treatment to vitamin E-deficient rats was associated with dose-dependent toxicity, resulting in 100%, 75%, and 50% mortality at concentrations of 2, 1, and 0.5 g/kg diet, respectively. This mortality was mainly due to extensive hepatic necrosis. Food intake and growth rates were reduced, while the relative weights of liver, kidneys, spleen, heart and brain, as well as the serum levels of GPT and GOT were significantly increased over the values of the untreated vitamin E-deficient control rats. The volumetric densities of ceroid pigment and the dolichol contents in liver and kidneys were not significantly modified. Lovastatin toxicity was partially prevented by vitamin E supplementation. However, in these supplemented rats, lovastatin treatment did not modify the volumetric densities of hepatic and renal ceroid, although the contents of hepatic and renal dolichol were significantly increased. No correlations could be found between levels of hepatic or renal ceroid and total dolichol content in vitamin E-deficient and supplemented rats. Leupeptin treatment to vitamin E-deficient rats only slightly reduced food intake and growth rates, and did not significantly modify the relative organ weights or the serum levels of cholesterol, GOT and GPT. Although in both vitamin E-deficient and -supplemented rats the leupeptin treatment consistently showed a tendency to increase the volumetric densities of hepatic and renal ceroid pigment, the differences with the control untreated rats were not statistically significant.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of unilateral ureteric occlusion on renal necrosis occurring in rats fed a methyl-deficient diet.

Wistar male rats were fed from weaning a methyl-deficient diet (groups I and II) or a standard commercial diet (groups III and IV). At the day 3 the left ureter was tied and divided in animals of groups I and III, while those in groups II and IV were sham operated. Rats of all groups were killed on days 8 and 10 to evaluate the incidence and extent of tubular necrosis (day 8) and tubular and cortical necrosis (day 10). The results of this study show that unilateral ureteric obstruction diminishes the incidence, severity and extent of necrosis in the same kidney.

Effect of chemical modification with p-bromophenacyl bromide on the enzymatic and lethal properties of phospholipase A2 from Bothrops alternatus (Víbora de la Cruz) venom.

The effects on lethal potency and enzymatic activity were determined following alkylation, with p-bromophenacyl bromide, of the acidic toxic phospholipase A2 from Bothrops alternatus. The modified B. alternatus enzyme, which lost its enzymatic activity, retained considerable toxicity. Histopathologic studies on mice have demonstrated features similar to those of the native enzyme. However, the distribution of the damage was different and the survival time was longer. It is concluded that the enzyme activity is not important for the lethal action of the enzyme although it influences the distribution of the damage and survival time.

Contribution of phospholipase A2 to the lethal potency of Bothrops alternatus (víbora de la cruz) venom.

Purified phospholipase A2 from Bothrops alternatus venom is one single protein species with a molecular weight of 15,000 and isoelectric point 5.08. When injected i.p. or i.v. at a dose of 0.7 microgram/g body weight it is lethal to mice, eliciting a typical syndrome of dyspnea, tachycardia, arrhythmia and irreversible shock. Post mortem and histopathologic studies have demonstrated that the lungs (massive pulmonary hemorrhage), heart (foci of myocardial and endocardial necrosis with interfibrillar hemorrhage), liver (congestion, hepatocytic microvacuolization with zones of massive necrosis) and kidneys (foci of tubular and glomerular necrosis) were severely injured. Except for the less extensive hemorrhages and the significantly longer survival time, the observed lesions are similar to those observed after the injection of lethal doses of whole venom. The lethal potency of the purified enzyme (LD50 i.p. 0.14 microgram/g body weight) is 46-fold greater than that of the whole venom (LD50 i.p. 6.4 micrograms/g body weight). The contribution of phospholipase A2 to the overall lethal effect of B. alternatus venom is suggested by the decreased lethal potency of a venom sample in which a significant amount of phospholipase A2 has been removed and the full restoration of the lethal potency upon supplementation of the depleted sample with purified enzyme. It is concluded that phospholipase A2 is a major component responsible for lethality of the whole B. alternatus venom, while the contribution of other venom components appears to be significant mainly in reducing the time of survival.

Nephrotic syndrome due to preeclampsia incidence of focal and segmental glomerular sclerosis

De 14 pacientes embarazadas que desarrollaron síndrome nefrótico e hipertensión arterial en el tercer trimestre de la gestación, en 7 se hallaron en la histopatología renal lesiones de preenclampsia y de escrerosis glomerular focal y segmentaria y en las 7 restantes sólo de preeclampsia. El hallazgo de la lesión esclerosante podría indicar una nefropatía preexistente complicada con una preeclampsia, o bien representar una lesión adicional de la glomerulopatía preeclámptica. Para analizar estas posibilidades, las enfermas fueron divididas en grupo I, con aquéllas que asociaron lesiones glomerulares de preclampsia y esclerosis segmentaria, y en grupo II, con sólo lesiones de preenclampsia. Ambos grupos fueron comparados con respecto a las alteraciones del riñon encontradas con microscopía óptica y electrónica, edades de las enfermas, paridad, antecedentes de hipertensión arterial, duración del embarazo, semana de comienzo de las manifestaciones clínicas de preeclampsia, duración de la preeclampsia, nivel de la presión arterial sistólica y diastólica, tasa de filtración glomerular, días entre el parto y la biopsia renal, recidiva de la preeclampsia, secuelas clínicas postparto (proteinuria y/o hipertensión arterial) y la evolución clínica alejada del parto. La confrontación de los grupos con respecto a los cambios observados con microscopía de luz mostró semajanza entre ellos, con excepción de las lesiones vinculadas a la esclerosis glomerular focal y segmentaria; en la microscopía ...

Vitamin B12 in blood of rats fed a methyl deficient diet

El objetivo de este trabajo fue medir la concentración de vitamina B12 en plasma y en eritrocitos de ratas alimentadas con una dieta hipolipotrópica. No conocemos que estos datos experimentales en ratas colina deficientes hayan sido reportados previamente. Se utilizaron ratas Wistar machos recién destetadas que se separaron en 4 grupos: CD, alimentadas con dieta hipolipotrópica; CS, alimentadas con dieta similar pero suplementada con colina e individual y diariamente apareadas con ratas líderes de grupo CD; C, alimentadas con dieta comercial, y W, que fueron sacrificadas en el momento del destete. Los cambios morfológicos en hígado, riñón y sangre periférica fueron correlacionados con la concentración de vitamina B12 en sangre determinada en los días 0 (grupo W) 5§ y 8§ (CD y CS). Los cambios hepáticos, renales y de sangre periférica fueron similares a los previamente publicados. En los animales del grupo CD se encontró anemia con marcadas alteraciones eritrocitarias y trombocitopenia, además de hígado graso y necrosis renal. Una disminución significativa en la concentración de vitamina B12 en plasma y eritrocitos en el 8§ día se encontró en los grupos CD y CS. La suplementación de colina previno el daño renal y hepático pero no así los cambios en sangre periférica debidos a la deficiencia de vitamina B12. El grupo CS mostró una menor concentración de vitamina B12 que el grupo CD con necrosis renal, lo que permite suponer una liberación por parte del tejido renal necrosado

A catabolin-like factor from porcine kidney.

Explants of pig kidney cortex and medulla release a catabolin-like factor (CLF). The CLF of both kidney cortex and medulla can be precipitated with ammonium sulphate, mainly in the 60-95 per cent fraction. By gel chromatography the kidney CLF showed a major active fraction at a molecular weight of around 22 500. Whole glomeruli and dissociated glomerular cells in culture also released into the medium a CLF that could be bioassayed in live cartilage but displayed no effect on dead cartilage. The possible role of such a local hormone is discussed.

Consumption coagulopathy in acute renal failure induced by hypolipotropic diets.

Weanling male rats fed on a hypolipotropic diet develop acute renal failure whose morphological features vary from focal tubular necrosis to cortical necrosis. We have sequentially studied the hemostatic mechanism in correlation with the morphology of various tissues, mainly renal and hepatic, in choline-deficient rats as well as in three control groups. No important changes were observed in the hemostatic mechanisms before the development of tubular necrosis. Along with tubular necrosis a consumption coagulopathy was found, evidenced mainly by a decrease in the activity of factors V and VIII as well as a prolongation in PTTK and Quick's time and a decrease in platelets. Fibrin degradation products were found in serum and urine and soluble fibrin monomer complexes in the former. Following tubular necrosis thrombi were found in the renal microvasculature. It is possible to speculate that the tubular necrosis induced by choline deficiency could produce an activation of the coagulation system which in turn would lead to thrombosis of the renal microcirculation and cortical necrosis.