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Biomedical subjects

Z Madar

Publications and source records attributed to Z Madar.

At least 73 records · Page 4Linked to original sources
PubMed1984

Binding sites of human growth hormone and ovine and bovine prolactins in the mammary gland and the liver of lactating dairy cow.

Membrane preparations and Triton X-100 solubilized fractions from the mammary gland and liver of the lactating dairy cow were capable of specific binding of [125I]hGH and [125I]oPRL. The specific binding of the latter was significantly lower and could not be increased by higher receptor levels. Displacement studies of [125I]hGh by hGH, bPRL and oPRL revealed that the two latter hormones have a 20-40-fold lower affinity for the receptor than hGH, although strong indications exist that they all bind or the same sites. This feature is unique for cows and does not exist or is much less pronounced in rodents.

Animals↗
PubMed1984

Iodohydroxybenzylpindolol binding to beta-adrenergic receptors of diabetic and control rat adipocytes' crude membrane.

We have characterized the binding of [125I]-Iodohydroxybenzylpindolol to rat adipocytes' crude membrane. The binding was rapid, reaching equilibrium within 19 min. Binding of [125I]-Iodohydroxybenzylpindolol was saturable with 9 nM. Half-maximal saturation provided an estimated Kd of 2.42 nM. The order for 125IHYP displacement by various compounds was (-)-propranolol (-)-isoproterenol greater than (-)-epinephrine greater than (-)-norepinephrine. [125I]-Iodohydroxybenzylpindolol binding was more sensitive to L-propranolol inhibition in crude membrane prepared from diabetic rat fat cells than in those prepared from controls. The basal cAMP level was identical in diabetic and control rat crude membrane. Isoproterenol increased the cAMP level in diabetic more than in control rats.

Adipose Tissue↗
PubMed1983

Down-regulation of prolactin receptors in the liver, mammary gland and kidney of female virgin rat, infused with ovine prolactin or human growth hormone.

Down regulation of prolactin (PRL) receptors resulting from i.v. infusion of oPRL or human growth hormone (hGH) into female virgin rats was demonstrated. A decrease of over 85% in the number of free receptors was achieved within 15 - 30 min using infusion of oPRL or hGH at 25 micrograms/h and remained at this level until the end of infusion. Ovine growth hormone or recombinant bovine growth hormone at ten-fold higher concentration had no effect at all. The decrease in the specific binding resulted from a lower number of binding sites and not from change in the dissociation constants. The decrease in the total receptors in the liver was more gradual and leveled off at 40 - 50% of the initial value. Our results suggest that a change in blood PRL or hGH level may lead to a new steady state in the number, occupancy and distribution of prolactin receptors.

Animals↗
PubMed1983

Effect of brown rice and soybean dietary fiber on the control of glucose and lipid metabolism in diabetic rats.

We have studied the effect of brown rice and soybean dietary fiber on the oral glucose tolerance test, plasma-insulin, -glucagon, -triglycerides, and cholesterol levels in control and streptozotocin-induced diabetic rats. Plasma glucose level after glucose loading in diabetic rats fed soybean fiber was considerably lower (60 and 120 min) than the corresponding group not receiving the fiber. Soybean fiber given to control rats decreased the plasma glucose at 60 min after the oral glucose test. Rice fiber decreased the plasma glucose of diabetic rats only at 60 min and the control rats fed with or without fiber elicited a comparable glycemic response. While soybean fiber significantly lowered the glucagon and triglyceride levels in both control and diabetic rats, rice fiber had no effect on these blood parameters. In conclusion, this study demonstrated the potential benefit of soybean dietary fiber over rice fiber in diabetes treatment with additional advantages resulting from its ease in usage either in a mixture of water or milk products and cooking. As well, being devoid of a disagreeable taste so characteristic of other fibers, patient acceptance is more forthcoming.

Animals↗
PubMed1983

3-O-methyl-D-glucose uptake in isolated rat hepatocytes. Effects of dexamethasone.

We examined the uptake of 3-O-methyl-D-glucose, a nonmetabolizable hexose, by isolated rat hepatocytes. The uptake of 3-O-methyl-D-glucose was linear for 1 min at 22 degrees, and Lineweaver-Burk analysis demonstrated an apparent Km of approximately 6 mM. Cytochalasin B (40 microM) and phloridzin (2 mM) inhibited 3-O-methyl-D-glucose uptake by 88% and 63%, respectively. D-Glucose (20 mM) inhibited the initial rate of 3-O-methyl-D-glucose uptake by 55% (p less than 0.001), whereas L-glucose was without any significant effect. The uptake of 3-O-methyl-D-glucose remained unchanged in the presence of Na+ (0-150 mM) in the incubation medium. After 30 min dexamethasone inhibited glucose uptake (the maximal effect being achieved in a time- and concentration-dependent manner) at 2 microM and 0.5 microM concentrations by 50% and 25%, respectively. Dexamethasone produced a decrease in the Vmax but did not change the Km. Insulin, glucagon, gastric inhibitory polypeptides, and pancreozymin had no effect on 3-O-methyl-D-glucose uptake in isolated hepatocytes. These findings are consistent with the conclusion that 3-O-methyl-D-glucose uptake in isolated rat hepatocytes occurs via a stereospecific, carrier-mediated, facilitated diffusion process. Dexamethasone decreases this process of facilitated diffusion in the isolated hepatocyte.

3-O-Methylglucose↗
PubMed1982

The kidney is the main site of interferon degradation.

Male Sprague Dawley rats (300 g) were infused by constant infusion into the jugular vein through 3-5 h with human leukocyte-derived interferon (HuIFN-alpha 10(6) units/h, 0.9 ml/h). Blood samples were collected every 20 min through the carotid. A steady-state level of interferon in serum (10(4) U/ml) was reached after 50 min of infusion, indicating fast removal of most of the infused material. Examination of interferon distribution in various tissues at the termination of the infusion revealed that over 85% of active interferon was found in the kidneys. No interferon was found in urine. Ligation of both kidneys resulted (after 2.5 h of infusion) in a ten-fold increase in interferon in serum and a minor increase in other tissues. No interferon was found in the kidneys. Simultaneous infusion of HuIFN-alpha, pepstatin and leupeptin (the well-known inhibitors of lysosomal proteinases) for 2.5 h had no effect on interferon concentration in serum and various tissues except in kidneys where a 5-fold increase was found. Mitochondrial-lysosomal fractions contained 55% of the total kidney interferon. Partial inhibition of proteolytic and HuIFN-alpha degrading activities at that fraction was also observed. These data, together with our previous findings of accumulation of injected interferon in the mitochondrial-lysosomal fraction of rats and monkeys' kidney cells, provide a further evidence for the main role of the kidney in HuIFN-alpha degradation.

Animals↗
PubMed1982

Estrogen stimulation of 3-o-methyl-D-glucose uptake in isolated rat hepatocytes.

The effect of in vivo and in vitro estrogen treatment on 3-O-methyl-D-glucose (30MDG) uptake in isolated rat hepatocytes was examined. A 1-h preincubation of isolated hepatocytes with 17 beta-estradiol (E2) or 17 alpha-ethynyl estradiol stimulated uptake of 30MDG in a dose-dependent fashion. The response appeared to be sterospecific, in that 17 alpha-estradiol was approximately 100-fold less effective than its 17 beta isomer. By itself, the triarylethylene antiestrogen, nafoxidine, slightly increased hepatocyte 30MDG uptake, while in combination with estrogen, nafoxidine completely blocked the effects of both E2 and 17 alpha-ethynyl estradiol. The protein synthesis inhibitor, cycloheximide, inhibited basal 30MDG uptake and abolished the stimulatory effect of estrogen. Kinetic analysis indicated that the estrogen effect resulted from an increase in the Vmax of the 30MDG transport system, with no measurable change in its Km. In vivo estrogen treatment, using either estrogen injections or continuous release Silastic E2 capsules, produced an increase in hepatocyte 30MDG uptake of 52-86%. A similar (66%) increase was seen in pregnant animals between the 14th and 19th days of gestation. These findings demonstrate that estrogens exert a rapid stimulatory effect on hepatocyte hexose transport. This effect is qualitatively similar to the response to estrogen of the hexose transport systems in other estrogen target tissues, such as the uterus. In addition, the results provide further support for the concept that the effects of the triarylethylene antiestrogens are both tissue and end-point dependent. Although previous studies have shown that nafoxidine exerts estrogen-like effects on hepatic renin substrate production, the present data indicate that, with respect to hepatocyte 30MDG, nafoxidine is almost a pure estrogen antagonist.

3-O-Methylglucose↗
PubMed1979

Composition and histological observations of enlarged pancreases of chicks adapted to raw soybean meal diets.

Chicks fed raw soybean meal (RSBM) as a sole protein source developed a significantly enlarged pancreas as compared to chicks fed heated soybean meal. No difference in DNA, RNA and protein content was observed, but the number of acinar cells was significantly higher in pancreases of chicks fed RSBM, after 14 and 28 days of feeding. Histological and ultrastructural analyses revealed that the enlargement of the pancreas resulted both from the hyperplasmic increase in the number of acinar cells and from the dilution of the acini by intercellular connective tissue and the appearance of cytopathogenetic areas.

Animal Feed↗
PubMed1978

The level and origin of amylase (EC 3.2.1.1) in the digestive tract of chicks receiving trypsin inhibitors in their diet.

1. Amylase (EC 3.2.1.1) activity found in the intestinal tract of chicks posterior to the stomach is of endogenous origin, as amylase in the food is inactivated by the low pH in the stomachs. 2. Ingestion of raw soya-bean diet (RSD) or of heated soya-bean diet (HSD) supplemented with trypsin inhibitors induced higher amylase activites in the lower part of the small intestine and caecum as compared with HSD. 3. Ingestion of RSD after ligation at the end of the duodenum, end of the ileum or one of the cacea, or injection of soya-bean trypsin inhibitor into a aligated caecum, indicated that there is no amylase synthesis by the intestinal tract cells or microflora as a response to the presence of RSD or trypsin inhibitors. 4. It seems that amylase found in the digestive tract of the chick is of pancreatic origin and the RSD or trypsin inhibitors induce higher pancreatic amylase secretion than HSD which (the additiona amylase) accumulates mainly in the caeca.

Amylases↗
PubMed1976

The comparative effect of prolonged feeding with raw and heated soybean mean on the growth response, pancreatic enlargement and pancreatic enzymes of chicks.

Prolonged feeding of chicks with raw soybean meal as the main protein source in the diet resulted in growth inhibition, pancreas enlargement, and increased content of pancreatic proteolytic enzymes. The effect of feeding with raw soybean meal as compared to heated soybean meal upon total intestinal enzymatic activities in chicks was tested. The tendency of chicks to overcome the effects of raw soybean meal is expressed mainly by the increase of biosynthesis and secretion of proteolytic enzymes in the pancreas.

Amylases↗
PubMedDate not supplied

Cataract development in diabetic sand rats treated with alpha-lipoic acid and its gamma-linolenic acid conjugate.

BACKGROUND: Diabetes commonly leads to long-term complications such as cataract. This study investigated the effects of alpha-lipoic acid (LPA) and its gamma-linolenic acid (GLA) conjugate on cataract development in diabetic sand rats. METHODS: Two separate experiments were conducted. In Experiment 1, sand rats were fed a "high-energy" diet (70% starch), an acute model of Type 2 diabetes, and injected with LPA. In Experiment 2, the animals received a "medium-energy" diet (59% starch), a chronic diabetic model, and were intubated with LPA or its GLA conjugate. Throughout the experiments, blood glucose levels and cataract development were measured. At the termination of the experiments, lens aldose reductase (AR) activity and lenticular reduced glutathione (GSH) levels were analyzed. RESULTS: LPA injection significantly inhibited cataract development and reduced blood glucose levels in rats fed the "high-energy" diet. Lens AR activity tended to be lower, while lenticular GSH levels increased. In sand rats fed a "medium-energy" diet (59% starch), LPA intubation had no effect on blood glucose levels and cataract development but GSH levels were increased. In contrast, sand rats intubated with GLA conjugate showed the highest blood glucose levels and accelerated cataract development. The conjugate treatment also decreased lenticular GSH content. CONCLUSIONS: The hypoglycemic effects of LPA are beneficial in the prevention of acute symptoms of Type 2 diabetes. It remains to be shown that the antioxidant activity of LPA is responsible for prevention or inhibition of cataract progression in sand rats.

Aldehyde Reductase↗
PubMedDate not supplied

Glucose turnover in normal and diabetic rats under anesthesia.

This report describes the effects of four anesthetic agents on glucose metabolism in rats. Ketamine and nubain drastically increased plasma glucose levels in normal rats. They also caused a high death rate as compared to nembutal and seconal and, therefore, were not useful for studies of glucose kinetics. Although both nembutal and seconal had a moderate effect on glucose metabolism, seconal was preferred for epinephrine studies. As this agent displayed a moderate effect on glucose kinetics, it was also deemed suitable for use in the studies of glucose kinetics in diabetic rat models. This study indicates that glucose and probably fat metabolism under anesthesia require considerable further research.

Anesthesia↗
PubMedDate not supplied

Is copper effect on glucose incorporation mediated by the insulin receptor in rat adipose tissue?

The insulin receptor is not the site for the stimulatory effect of copper on glucose incorporation into total lipids by adipose tissue; prewashing of adipose tissue of rats fed a stock diet in an insulin-free medium increases the glucose incorporation into total lipids in the presence of 0.1 unit insulin from 220 above control to 430% in the nondiabetic and from 154 to 230% in the streptozotocin-diabetic rat. In contrast, glucose incorporation in the presence of CuCl2 X 2H2O is unaffected by prewashing, being the same in the prewashed as in the unwashed adipose tissue. On the other hand, mild trypsin digestion of adipocytes decreases the glucose incorporation in the presence of 28.5 mU insulin, from 201 to 126% - whereas the effect of copper on glucose incorporation is the same in the trypsin-treated or untreated adipocyte. In order to obtain maximal copper effect the adipocyte has to be preconditioned by insulin; preincubation of diabetic adipose tissue first for one hour with 0.1 unit insulin, and another hour with 100 micrograms CuCl2 X 2H2O added to the medium, results in greater glucose incorporation (230% above control) than when incubated alone with either CuCl2 X 2H2O (125%) or insulin (154%) for two hours. In addition to its previously noted effect on the in vivo insulin release, copper increased the number of the insulin receptor sites in adipocytes.

Adipose Tissue↗
PubMedDate not supplied

The influence of extruding corn grain on glucose metabolism in pregnant ewes.

Glucose metabolism was studied in 31 pregnant ewes fed mixtures (50:50) of chopped alfalfa hay and corn grain given in whole (HWC) or extruded form (HEC). Number of fetuses was 1 (n = 10), 2 (n = 11) or 3 (n = 10). Diets were supplied at three dietary levels: maintenance (1.0 M), 1.25 x maintenance (1.25 M) or twice maintenance (2.0 M). Glucose metabolism was estimated by a double isotope dilution procedure at days 97-121 of pregnancy. Glucose entry rate (GER) was higher (P < 0.04), and glucose irreversible loss rate (GILR) tended to be higher (P < 0.07) in ewes given HEC than HWC. Dietary level (P < 0.001) and the number of fetuses (P < 0.005) affected GER and GILR positively. These results provide a probable explanation for higher birth weights previously found in lambs born to HEC-, compared with HWC-fed dams.

Animal Feed↗