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Biomedical subjects

C V Ramakrishnan

Publications and source records attributed to C V Ramakrishnan.

At least 19 recordsLinked to original sources
PubMed1990

Effect of undernutrition on the chemical composition and the activity of alkaline phosphatase in soluble and particulate fractions of the newborn rat calvarium and femur. I: Effect of gestational undernutrition in the rat.

We studied the effect of maternal protein deficiency on the development of the rat calvarium and femur. The results show that maternal protein deficiency during gestation leads to fetal growth retardation, and that the calvarium is more affected than the femur. A significant decrease in the activity of alkaline phosphatase was found in the soluble fraction in both the calvarium and the femur. However, this was not true in the case of the particulate fraction in which a significantly increased activity was found. This increase was not associated, however, with a concomitant increase in calcium and phosphorus (per 100 g fresh bone).

Alkaline Phosphatase↗
PubMed1990

Effect of undernutrition on the chemical composition and the activity of alkaline phosphatase in soluble and particulate fractions of the rat calvarium and femur. II: Effect of preweaning undernutrition in the suckling rat.

We studied the effects of undernutrition during the suckling period on the development of the calvarium and the femur of rat pups suckling dams fed a 20% or 5% protein diet. The results show that the maturation of bone is delayed by undernutrition. In both the calvarium and the femur, the particulate fraction alkaline phosphatase reflects the rate increments in calcium and phosphorus uptake in control animals. This association is affected in the undernourished pups, as both the alkaline phosphatase activity in particulate fraction and the calcium and the phosphorus uptake decreased. However, the extent of disturbance was more prominent in the femur than in the calvarium, suggesting that during postnatal undernutrition the calvarium is less affected when compared to prenatal undernutrition, where the femur is less affected. The results from these studies suggest that proper nutrition is necessary for bone development during both the prenatal and postnatal period.

Alkaline Phosphatase↗
PubMed1990

Effects of postweaning protein malnutrition on intestinal inositol phosphatase activities in normally weaned and neonatally undernourished rats.

Postweaning protein malnutrition imposed on normally weaned or neonatally undernourished rats fed a low-protein diet induced retardation of body and small intestinal growth. A sparing effect on intestinal growth as compared to body growth was observed during protein malnutrition. Postweaning protein malnutrition in normally weaned rats resulted in a significant elevation of specific activities of inositol triphosphatase and phytase in duodenum and jejunum without affecting the activity in ileum. On the other hand, protein malnutrition imposed on neonatally undernourished rats resulted in a significant decrease of enzyme activities in small intestinal segments. These results suggest altered activity of intestinal inositol phosphatase in postweaning protein malnutrition with the direction of effects dependent on the neonatal nutritional status.

6-Phytase↗
PubMed1990

Alcohol exposure and undernutrition: effects on lipid metabolism and alcohol partitioning in rat brain regions in vitro.

The effects of maternal alcohol consumption and undernutrition on lipid metabolism and alcohol partitioning in brain cortical and stem slices of pups were studied under in vitro conditions. Alcohol administration along with a normal diet during gestation and lactation resulted in an increase in the synthesis of cholesterol in cortical and stem slices associated with decreased entry of alcohol. Phospholipid metabolism was not affected in the cortex, whereas the incorporation of [32P] was found to be altered in the brain stem, indicating regional differences with respect to alcohol effects. Undernutrition induced by feeding the mothers a low protein diet, on the other hand, decreased the incorporation of labelled precursors into lipids in cortex and stem. The changes in lipid metabolism observed in the high protein alcohol pups were not evident in the brain regions of undernourished pups exposed to alcohol and the partitioning of alcohol was not altered.

Acetates↗
PubMed1989

Lipid composition of brain regions during chronic maternal alcohol treatment and withdrawal in the rat.

The lipid composition of whole brain, cerebrum, cerebellum and brain stem was studied in rat pups exposed to alcohol during prenatal and postnatal period and subsequent withdrawal or continuation during postweaning period. The concentrations of cholesterol and galactolipids were increased in the whole brain and brain regions of the pups exposed to alcohol. Even after 6 weeks of withdrawal from alcohol during postweaning period, the lipid levels were significantly higher compared to the controls. These observations suggest possible alterations in the functions of CNS related to membrane integrity.

Animals↗
PubMed1988

Interaction of alcohol and protein deficiency on rat brain synaptosomal (Na+-K+)-ATPase.

Administration of low amounts of ethanol for a prolonged period increases rat brain synaptosomal (Na+-K+)-ATPase activity, the increase being less in the protein deficient rats. The adaptive mechanism to offset the stress imposed by the continued presence of ethanol seems to be depressed by low plane of nutrition. In vivo and in vitro effects of ethanol on (Na+-K+)ATPase seems to be different.

Animals↗
PubMed1988

Effect of maternal alcohol consumption on the lipid composition of CNS in the offspring.

Maternal alcohol consumption at a level that does not affect calorie intake increases cholesterol concentration and content as well as incorporation of labeled glucose into cholesterol in the brain and spinal cord of newborn rat pups. Continued consumption of alcohol during lactation also affects the galactolipid concentration in the brain and spinal cord of pups at 21 days of age, and this increase seems mainly to be due to an increase in content of myelin lipids. Analysis of myelin shows that the concentration of phospholipids also increases in this fraction. The increase in incorporation of labeled glucose into these membrane lipids suggests an increase in the synthesis of these lipids, which prevents fluidization of the membrane by alcohol. That in the brainstem the increase in levels of cholesterol and galactolipids is higher than in other regions and that there is also an increase in content of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine suggest that the brainstem needs better protection against fluidization.

Animals↗
PubMed1986

Effects of pre-weaning undernutrition and post-weaning rehabilitation on polyphosphoinositide pools in rat brain regions.

In order to assess the effects of undernutrition during the pre-weaning period on polyphosphoinositide (PolyPI) pools in rat cerebral cortex, brain stem, and cerebellum, dams were fed 5% (L-) or 22% (L+) protein diets from birth to weaning and the pups were used at this age for analyses. To examine rehabilitation post-weaning, L- and L+ pups were fed 22% protein diets (P+) for an additional six week period. Rats were decapitated and the dissection begun either immediately ("0 min" samples) or 10 min later (10 min samples). Body and tissue weights, and cerebroside levels were determined in addition ot PolyPI concentrations. In brain the extent of disappearance of PolyPI during the 10 min post-mortem period paralleled the content of gray matter: cerebral cortex greater than cerebellum greater than brain stem in all groups regardless of diet. Levels of PtdIns4P and PtdIns4,5P2 were decreased by 40% and 70% respectively in cerebral cortex of L- "0 min" samples. Deficits of both lipids in brain stem and cerebellum were 40-50%. In the L- 10 min samples, deficits were 20-30% in all three regions as compared with L+ 10 min levels, indicating the presence of a portion of both lipids affected only moderately by nutritional insufficiency. The effects on this relatively inert pool, much of it localized in myelin, were reversed on nutritional rehabilitation. The PolyPI pool lost post-mortem in L+ brain regions was practically absent in L- brain regions and was not restored in L-P+ animals. Thus, this study indicates that a metabolically labile pool, primarily located in gray matter structures, is more sensitive to nutritional deprivation during the pre-weaning period than the more stable pool. The precise role and function of these pools remain to be determined.

Animals↗
PubMed1986

Effects of pre- and postweaning undernutrition on polyphosphoinositide pools in rat kidney.

The effects of undernutrition on polyphosphoinositide levels in rat kidneys removed and frozen immediately after animal death or 10 min later were determined. Weanling (21-day-old) rats of dams fed a 5 or 22% protein diet and litters fed either normal or protein-deficient diets for an additional six wk were used. Nutritional deprivation lowered phosphatidylinositol-4-phosphate (PtdIns4P) preferentially (35-40%) but preserved phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2) at weaning. This effect was not completely reversed in animals nutritionally rehabilitated after weaning. Postweaning protein deficiency did not reduce the levels of these lipids. Postmortem loss was the same for all five groups, minimal for PtdIns4P and about one-third for PtdIns4,5P2.

Aging↗
PubMed1986

Three chemotherapy studies of tuberculous meningitis in children.

Chemotherapy studies were undertaken in 180 patients with tuberculous meningitis. They were treated for 12 months with 1 of 3 regimens: the first consisted of streptomycin, isoniazid and rifampicin daily for the first 2 months, followed by ethambutol plus isoniazid for 10 months; in the second, pyrazinamide was added for the first 2 months, and in the third, rifampicin was reduced to twice weekly in the first 2 months. Steroids were prescribed for all the patients in the initial weeks of treatment. Approximately 50% of the patients were aged less than 3 years. On admission, 13% of the patients were classified as stage I, 77% as stage II and 9% as stage III. Cerebrospinal fluid (CSF) culture results were available for all the 180 patients and M. tuberculosis was isolated in 59 (33%). CSF smear results for acid fast bacilli were available only for the 103 patients admitted to the second and the third studies, and of these in 60 (58%) the CSF was positive either by smear or culture. The response to therapy was similar in the 3 studies. Despite administration of rifampicin for 2 months, the mortality was high. In all, 27% of the patients died of tuberculous meningitis, 39% had neurological sequelae and 34% recovered completely. There was a strong association between the stage on admission and the mortality rate, the deaths being highest in stage III. In the first study, when isoniazid was prescribed daily in a dosage of 20 mg/kg, 39% of the patients developed jaundice; however, when the dosage was reduced to 12 mg/kg, the incidence fell to 16%. In the third study, where rifampicin was administered twice a week, the incidence of jaundice was much lower (5%).

Antitubercular Agents↗
PubMed1986

Inositol phosphatase in developing rat duodenum, jejunum and ileum.

Inositol phosphatase and phytase activities in different segments of the rat small intestine were measured during postnatal development. In the duodenum and jejunum, inositol phosphatase activity (units/g tissue) was low during the suckling period and increased at weaning, reaching a peak of activity at 4 weeks of age. In the ileum, peak activity was observed during the suckling period with a sharp decline at weaning. Phytase activity was very low during the suckling period in all segments, and increased to exhibit a peak at 4 weeks of age in the duodenum, and to a lesser extent in the jejunum (low activity was maintained in the ileum). The content of inositol phosphatase activity in the duodenum increased rapidly during the suckling period to reach its maximum at 4 weeks of age. This suggests a relationship to cell proliferation rate in the small intestinal mucosa.

6-Phytase↗
PubMed1985

Studies on inositolphosphatase in rat small intestine.

The possibility that inositolphosphatase differs from other intestinal phosphatases was tested by comparing several enzymatic characteristics of phosphatase activities of rat intestinal homogenate acting on various specific substrates. Optimum pH and temperature, Km, Vmax, heat stability, inhibition and metal ion requirement studies suggest that inositolphosphatase differs from phytase and p-nitrophenylphosphatase. Furthermore, we found that inositolphosphatase activity was about 2 times higher in duodenum and jejunum than ileum. It sedimented (90-100%) with a high-speed particulate fraction of mucosal homogenate; 42% of the activity was separated with the brush border membrane isolated from mucosal homogenate. Partial separation by gel filtration on Sephadex G200 and chromatography on phenyl Sepharose CL 4B provided additional evidence to suggest that inositolphosphatase and phytase are different enzymes.

6-Phytase↗
PubMed1984

Effect of ethanol on rat brain polyphosphoinositides.

Female rats were allowed to consume ethanol during gestation and lactation, and brain polyphosphoinositides of the 21-day-old pups were quantified. Ethanol intake prevented the disappearance of the metabolically labile pools of phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bis-phosphate, which are rapidly degraded in the control group. In contrast, preweaning undernutrition left the size of these pools virtually unchanged, indicating a differential effect of the two nutritional regimens.

Animals↗
PubMed1983

Effect of thiamine deficiency and undernutrition on the lipid composition of rat spinal cord at 21 days of age.

Maternal thiamine deficiency and undernutrition are found to cause significant deficits in body and spinal cord weights of the offspring at 21 days of age. The concentration of different lipids is found to be decreased significantly in both experimental groups as compared to normal controls. However, these deficits do not seem to differ between the undernourished and the thiamine-deficient groups. The results suggest a general effect of growth retardation rather than thiamine deficiency per se on the lipid composition of spinal cord.

Animals↗
PubMed1983

Studies on polyphosphoinositides in developing rat brain.

Polyphosphoinositides in rat brain exist in two forms: the metabolically active form that is readily attacked by the polyphosphoinositide phosphohydrolases, and the inert form that is attacked by the enzymes at a slower rate. The two pools continue to increase even during the postweaning period, suggesting a role in glial as well as myelin development apart from their role in neurons.

Aging↗