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Biomedical subjects

N Raghuramulu

Publications and source records attributed to N Raghuramulu.

At least 19 recordsLinked to original sources
PubMed2000

Oral glucose tolerance is unaltered in vitamin D-deficient rat.

Vitamin D deficiency has been reported to result in impaired glucose tolerance and decreased insulin secretion when glucose is administered either intravenously or intraperitoneally. The aim of the present study was to study oral glucose tolerance and glucose absorption in a vitamin D-deficient rat model. Oral glucose tolerance tests were carried out in vitamin D-deficient and control rats, and this was found to be unaltered in the deficient state. Intestinal absorption of glucose was drastically reduced in the deficient animal and was found to be due to a reduction in the sodium-dependent component of glucose transport. Thus the unaltered oral glucose tolerance in the vitamin D-deficient rat is probably due to impaired absorption of glucose.

Animals↗
PubMed1999

Is vitamin D redundant in an aquatic habitat?

Certain fish are very rich sources of vitamin D as compared to most of the higher vertebrates which have insignificant amounts of this vitamin. Not only the teleosts, which possess a calcified skeleton, but also the elasmobranchs, which lack calcified skeleton, contain extremely high concentrations of this vitamin, leading to the speculation that the function of vitamin D in fish may be different from its known classical functions in terrestrial animals. Interestingly, the two most common calcemic hormones associated with Ca and P homeostasis in higher vertebrates are either missing [parathyroid hormone (PTH)] or inactive [calcitonin (CT)] in fish. In fact, these hormones appear to have developed after transition of life from water (Ca-P rich environment) to land (environment poor in Ca and P). Thus, living in an aquatic environment with a continuous rich supply of Ca and P, do fish need vitamin D? If so, does it need to be converted to its polar forms? Additionally what are the functions of vitamin D and its metabolites in fish? Since fish stand between the invertebrates and higher vertebrates in evolution, they serve as a unique model for the study of the evolutionary and physiological significance of vitamin D. Investigations have demonstrated that the source of a high amount of vitamin D in them is primarily through their food-chain (plankton). In addition, it appears from the studies in fish that vitamin D perhaps had no physiological function in the calcium-rich aquatic environment, and its metabolism was essentially for catabolic purposes. During the course of evolution, when life started on calcium poor terrestrial environment, vitamin D became functional and its metabolism, an anabolic one, was concerned with calcium homeostasis.

Animals↗
PubMed1999

Vitamin D2 is not biologically active for Rora (Labeo rohita) as vitamin D3.

The present investigation was directed towards finding the relative biopotency of vitamin D3 and D2 in fish. The freshwater column feeder fish Labeo rohita (Rora) was used for the study. The feeding of Rora with graded levels of vitamin D2 (550, 1,100 and 1,650 i.u./kg diet) and vitamin D3 (1,100 and 1,650 i.u./kg diet) resulted in no behavioural or morphological changes in comparison with the group fed a vitamin D-deficient diet. Also, the growth rate, feed efficiency, mortality rate, carcass protein, total lipids, calcium and phosphorus were found to remain unaltered in the vitamin D-deficient fish and fish fed any form of the vitamin. Further, there is no difference in any of the above parameters between the different doses of vitamin D3 or vitamin D2. Thus, the results of this study indicate that both of the forms of vitamin D (D2 or D3) are not biologically active for Rora (Labeo rohita) as a representative of freshwater fish.

Animals↗
PubMed1999

Vitamin D3 and its metabolites have no role in calcium and phosphorus metabolism in Tilapia mossambica.

The physiological function of vitamin D in fishes still remains uncertain. Earlier we observed no relationship between vitamin D3 content of several freshwater fishes and their calcemic/phosphatemic status and bone mineral content. In the present study the effects of vitamin D3 and its metabolites, 25-hydroxy vitamin D3 (25-OH-D3) and 1,25-dihydroxy vitamin D3 [1,25-(OH)2D3], administration on serum calcium-phosphorus levels, intestinal calcium absorption, whole-body calcium-phosphorus uptake, and gill calcium binding protein (CaBP) activity in the freshwater fish, Tilapia mossambica (Tilapia) was examined. It was observed that vitamin D3 and its metabolites could alter neither serum calcium-phosphorus levels nor intestinal calcium absorption and gill CaBP activity in fish at various doses. Further, the whole-body uptake of labelled calcium and phosphorus was also unaffected by vitamin D3/1,25-(OH)2D3 at different levels and/or at various lengths of time. Thus these studies indicate that unlike in terrestrial vertebrates, vitamin D3 or its metabolites are not needed for calcium-phosphorus homeostasis in fish.

Animals↗
PubMed1998

Vitamin D metabolism in tilapia (Oreochromis mossambicus).

The present investigation was carried out to study the conversion of [3H]vitamin D3 and 25-OH-D3 in vivo and in vitro in freshwater tilapia (Oreochromis mossambicus). A metabolite co-migrating with 1,25-(OH)2D3 formed from [3H]vitamin D3 in vivo was about 3-fold more concentrated than that of 25-OH-D3. The conversion of 25-OH-[3H]D3 to a product co-eluting with 1,25-(OH)2D3 was several-fold higher in liver than in kidney. Our data suggests that the tilapia 'liver' may be a major site for vitamin D metabolism.

Animals↗
PubMed1998

Vitamin D is not an essential nutrient for Rora (Labeo rohita) as a representative of freshwater fish.

This investigation was directed towards finding the need of vitamin D for fish. The freshwater column feeder fish Labeo rohita (Rora) was used for the study. Early fry stage fish were divided into four experimental groups of 350 each: two groups were kept in natural light, while the other two were maintained under total darkness. One each of the light and dark-grown groups was supplied dietary vitamin D3 [1,650 i.u/kg diet], whereas the other groups were fed a vitamin D-deficient diet for six months. The known vitamin D-related functions and growth parameters were studied in these four experimental groups of fish. The results showed that fish reared on vitamin D-deficient diet and in dark did not have even traces of liver vitamin D, indicating a state of vitamin D deficiency in these fish. No significant differences were observed in percent bone to body weight or dry matter of the vitamin D-deficient/supplemented groups of fish grown in light/dark. Further, it was also observed that there were no significant changes in bone and carcass ash or calcium and phosphorus content in response to vitamin D3 supplementation as compared to the groups which did not receive vitamin D3 (grown both in light and dark). Also, there was little change in several other parameters like carcass protein and lipid, mortality rates, hepatosomatic index, and feed efficiency between the vitamin D-deficient/supplemented groups of fish. Thus, these findings suggest that vitamin D may not be an essential nutrient for Rora (Labeo rohita) as a representative of freshwater fish.

Animals↗
PubMed1998

Bioactive phytochemicals with emphasis on dietary practices.

Diet can modify the pathophysiological processes of various metabolic disorders and can be an effective preventive strategy for various disease processes most of which are known to involve oxidative damage. Both nutrient and non-nutrient components of the diet have been recognized for their anti-oxidant and other potential benefits. Plant foods contain phytochemicals such as flavonoids, phenolic acids, etc., which show biological activity. Some common foods used in Indian culinary practices were assessed for their anti-oxidant, anti-mutagenic and anti-carcinogenic effects and vitamin D activity and evaluated for their plausible biological effects. Green leafy vegetables had the highest anti-oxidant activity followed by wheat and rice. Cooking decreased this activity. Eugenol, the active principle of clove, was shown to offer protection against CCl4 induced hepatotoxicity in rats. It also showed anti-peroxidative activity in addition to decrease in O2 formation. Studies on the anti-carcinogenic effect of turmeric/curcumin revealed that both are potent anti-mutagens in vivo and reduce the adducted DNA levels in liver of rates challenged with B(a)P. In another study, Syrian hamsters receiving turmeric/curcumin through diet or local paint on cheek pouch had lower tumour burden as well as adducted DNA level against 7-12-DMBA challenge. Turmeric/curcumin were found to be better anti-tumour agents when given in the post initiation phase of carcinogenesis. The beneficial effect of turmeric was found to be due to its anti-oxidant potential. Studies on humans at risk of palatal cancer due to reverse smoking showed that turmeric (1 g/day) for 9 months had a significant impact on the regression of precancerous lesions. Onion and garlic also possess anti-mutagenic principle. Further studies on the bioactive phytochemicals in plants showed that certain plants belonging to Solanaceae (Cestrum diurnum, Lycopersicon esculentum and Solanum melongena) have calcinogenic potential and vitamin D like activity. In view of the vast data on bioactive principles from plants, it is suggested that dietary prevention coupled with other life-style changes in perhaps the right answer for prevention of cancer and other chronic diseases in India.

Animals↗
PubMed1997

Vitamin D3 in Tilapia mossambica: relevance of photochemical synthesis.

The capability of fish to synthesize vitamin D on exposure to ultraviolet (UV) light was examined. Purposeful exposure of the freshwater fish Tilapia mossambica (Tilapia) to artificial UV light (300 nm) resulted in a significant increase of vitamin D3 with a concomitant decrease in provitamin D3 [7-dehydrocholesterol (7-DHC)], indicating that provitamin D3 was converted to vitamin D3. However, only 0.13% of the intraperitoneally injected 4-14C cholesterol was recovered in the vitamin D3 and 25-hydroxyvitamin D3 (25-OH-D3) fractions after 15 h of irradiation. Thus, although fish is capable of photosynthesizing vitamin D through constant, prolonged exposure to UV light of appropriate wavelength, the contribution of this mode of synthesis is unlikely to be of any significance in its natural habitat.

Animals↗
PubMed1996

Vitamin D3 and its metabolites in the tomato plant.

The tomato plant has been demonstrated to have vitamin D-like activity. The activity was present in the leaves but not in the fruit of the plant. The chloroform extract of the leaves (containing free vitamin D and its metabolites) and the ethanol extract of the residue (containing the glycosidic forms) were partially purified by column chromatography. The fractions corresponding to authentic vitamin D3, 25-hydroxy vitamin D3 and 1,25-dihydroxy vitamin D3 were tested for biological activity and analysed by HPLC. The results indicate that the plant contains vitamin D3, 25-hydroxy vitamin D3 and 1,25-dihydroxy vitamin D3 and their glycosidic forms. Free vitamin D3 was observed to be the major active principle and the concentration of the free forms of the metabolites was higher than the corresponding glycosides.

Alkaline Phosphatase↗
PubMed1986

Relationship between measles, malnutrition, and blindness: a prospective study in Indian children.

A prospective study was conducted in slum children to determine the incidence of post-measles corneal disease and to clarify its relationship with nutritional status. A total of 318 cases of measles were identified over a period of 15 mo; maximum incidence was observed for children between 1-2 yr. Most of the children showed weight loss and serum proteins decrease during the acute stage of measles. Corneal lesions were observed in 3% of the children, and the lesions responded well to treatment. Serum vitamin A and RBP levels were significantly depressed during the acute stage of measles but were restored to normal 8 wk after recovery. There were no significant differences in the serum levels for those with and without eye lesions, which suggests that these lesions may not be mediated simply through the effect of infection on serum concentration of vitamin A.

Blindness↗
PubMed1986

Absorption of vitamin A by children with diarrhoea during treatment with oral rehydration salt solution.

The results of a study of absorption by children of vitamin A indicate that absorption is lower in children with acute diarrhoea compared with normal children. The glucose or electrolytes present in solutions of oral rehydration salts had no effect on the absorption. Despite malabsorption, 70% of the administered dose of 100 000 IU of vitamin A in 500 ml of fluid was absorbed and retained.

Child, Preschool↗
PubMed1986

Pathogenesis of corneal lesions in measles.

The mechanism of pathogenesis underlying the development of corneal lesions in measles was investigated in 125 children suffering from measles and 66 age- and sex-matched healthy controls. Forty age-matched children with bronchopneumonia were investigated on similar lines to delineate the role played by vitamin A and measles individually in the development of corneal lesions. The results indicate that the pathogenesis of corneal lesions in measles is indeed multifactorial. Vitamin A deficiency alone or measles keratitis per se may not explain the mechanism completely. The immunosuppression induced by the local proliferation of the measles virus in the eye might trigger the invasion of pathogenic microbes which damage the cornea. The structural integrity of the cornea is already compromised by vitamin A deficiency and lesions of measles keratitis.

Bronchopneumonia↗
PubMed1982

Studies on vitamin D metabolism in malnourished children.

1. Basal levels of serum 25-hydroxy vitamin D (25-OHD) were estimated in ten normal children and twenty-seven children with protein-energy malnutrition. 2. Five normal children and fourteen malnourished children were administered a single massive dose of 15 mg vitamin D orally and the remaining children received oral supplements of 50 micrograms vitamin D daily for 20 d. Blood samples were obtained after 10 and 20 d of dosing and serum 25-OHD levels were repeated. 3. The basal serum 25-OHD levels were significantly lower (P less than 0.05) in malnourished children than in normal children. 4. Administration of a single massive dose of vitamin D as well as daily supplementation of small doses resulted in significant increases in serum 25-OHD levels within 10 d. However, the increase with a massive dose was of a higher magnitude. There was no significant difference between the normal and malnourished children. 5. The binding capacity of serum to 25-OHD was similar in both the groups. 6. These results suggest that vitamin D metabolism is not altered in protein-energy malnutrition.

Blood Proteins↗
PubMed1982

Serum prolactin levels in undernourished Indian lactating women.

1. Serum prolactin (PRL) levels, both basal and post-suckling peak, were estimated in fifty-seven lactating women. 2. Basal PRL levels were significantly higher in all lactating women irrespective of the duration of lactation as compared to the levels in non-pregnant, non-lactating women. 3. There was significant positive correlation (r 0.69, P less than 0.001) between the basal PRL levels and the post-suckling peak values. 4. After 8 months of lactation, peak post-suckling, PRL levels were not significantly different from basal values. 5. Basal PRL levels were significantly lower (P less than 0.05) in mothers whose infants were being supplemented. 6. PRL levels were not related to the mother's nutritional status as determined by body-weight. 7. The findings suggest that high PRL levels during lactation prolong the duration of lactional amenorrhoea and hence the relative infertility.

Adult↗
PubMed1980

The effect of dietary protein on the biological activity of cholecalciferol and its metabolites in the rachitic rat.

Rats maintained on low-protein rachitogenic diets show increased intestinal calcium transport, serum inorganic phosphate and increased endochondral calcification responses to calciferol, 25-hydroxycholecalciferol (25-OH-CC) and 1,25-dihydroxycholecalciferol (1,25-(OH)2CC). Because enhanced responses are observed with 1,25-dihydroxycholecalciferol as well as its precursors, it is unlikely that the effect of dietary protein is mediated by a change in the calciferol-25-hydroxylase and the 25-hydroxycholecalciferol-1 alpha-hydroxylase. Instead, it appears that either metabolism of 1,25-dihydroxycholecalciferol or its activity in the target organs is affected.

Animals↗
PubMed1980

Serum 25-hydroxy-vitamin D levels in malnourished children with rickets.

Serum levels of calcium, phosphorus, alkaline phosphatase, and 25 hydroxy-vitamin D (25-OH-D3) were measured in normal and malnourished children with and without rickets. Children with rickets had clinical, biochemical, and x-ray evidence of the disease; most of them were malnourished. 25-OH-D3 levels were lower than in normal children. After treatment with vitamin D their condition improved. 25-OH-D3 levels were also found to be reduced in malnourished children without rickets. These studies show that rickets is common in malnourished children. Inadequate exposure to sunlight appears to be the factor mainly responsible for the high incidence of the disease. In addition, malnutrition perhaps contributes to the development of rickets.

Alkaline Phosphatase↗
PubMed1979

Serum retinol-binding protein and vitamin A levels in malnourished children.

Serum levels of vitamin A and retinol-binding protein (RBP) were measured in children with vitamin A deficiency, in children with protein-energy malnutrition (PEM) and in normal children, before and after administration of 100 000 IU of water-miscible vitamin A. Serum vitamin A and RBP levels were significantly low in children with vitamin A deficiency and in children with severe PEM, whereas the values in milder grades of PEM were similar to those of normal subjects. In severely malnourished children with corneal lesions, serum vitamin A concentration was reduced to a much greater extent than the level of serum RBP. Administration of vitamin A resulted in a significant increase in serum levels of both the components within 4 hours in all the 3 groups of children. The increase in RBP concentration observed in children with PEM was similar to that in vitamin A deficient children. These results indicate that in malnourished children, particularly in those who are at risk of developing keratomalacia, vitamin A is the main limiting factor. It is, therefore, recommended that children with PEM should be treated with vitamin A in addition to dietary protein and calories.

Child↗