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Biomedical subjects

S Shankar

Publications and source records attributed to S Shankar.

At least 91 records · Page 5Linked to original sources
PubMed1988

Retinoic acid supplementation of a vitamin A-deficient diet inhibits retinoid loss from hamster liver and serum pools.

These studies were performed to follow a spectrum of relevant parameters in male Syrian golden hamsters fed either a vitamin A-deficient diet or the same diet supplemented with retinoic acid at 3 micrograms/g diet. Body weight and life span were not affected by the vitamin A-deficient diet until after 6-7 wk. Squamous metaplastic lesions of the Formalin-fixed tracheas were not generally observed in the hamsters fed the deficient diet until 6-7 wk, at which time blood retinol and liver retinyl palmitate levels had also decreased. Blood glucose levels remained normal (90 mg/dl) until about 7 wk but declined to about 40% of normal at 9 and 10 wk. Dietary retinoic acid supplementation of the vitamin-deficient diet (3 micrograms/g diet) inhibited the loss of retinol from blood and of retinyl palmitate from the liver so that these compounds were still present at 10 wk, but were not detectable in hamsters fed the vitamin A-deficient diet without retinoic acid.

Animals↗
PubMed1987

In vivo formation of tritium-labeled lactic acid from [2-3H]mannose or [15-3H]retinol by hamster intestinal epithelial cells.

In studies designed to reexamine the in vivo occurrence of retinyl phosphate mannose we injected hamsters intraperitoneally with either [2-3H]mannose or [15-3H]retinol and sacrificed the animals 15 min later. The small intestine was removed, the epithelial cells were scraped, and a methanolic extract of the labeled cells was prepared and chromatographed on a Mono Q anion-exchange column. Intraperitoneal administration of either [2-3H]mannose or [15-3H]retinol lead to the formation of a tritium-labeled anionic compound with a retention time on the Mono Q column similar to that of standard retinyl phosphate mannose. However, the biochemical properties of this labeled anionic compound were those expected of an organic acid and not retinyl phosphate mannose. The compound was resistant to both strong acid hydrolysis and mild base hydrolysis, as well as digestion with alpha- or beta-mannosidase, phosphodiesterase I, nucleotide pyrophosphatase, or beta-glucuronidase. When chromatographed on an Aminex HPX-87H organic acid analysis column or a silicic acid column the labeled anionic compound derived from either [2-3H]mannose or [15-3H]retinol comigrated with standard lactic acid. Treatment of the anionic compound derived from [2-3H]mannose with lactate oxidase or L-lactate 2-monooxygenase resulted in the formation of a tritium-labeled product that cochromatographed, respectively, with pyruvate or acetate on the Aminex HPX-87H column. However, treatment of the anionic compound derived from [15-3H]retinol with these same two enzymes resulted in a labeled product that migrated on the Aminex column at the same position as tritiated water. This result demonstrated that the labeled hydrogen was removed during enzymatic digestion and suggested that it was present on the second carbon of lactic acid. During the course of these studies no evidence for the in vivo labeling of a compound with the properties of retinyl phosphate mannose was found. Since [2-3H]mannose leads to labeled lactic acid in vivo the tritium label must not always be lost, as expected, during the entry step into glycolysis in which mannose 6-phosphate is converted to fructose 6-phosphate. The results suggest that an intramolecular hydrogen transfer from the C-2 position of mannose 6-phosphate to the C-1 position of fructose 6-phosphate can occur during the phosphomannose isomerase reaction. The finding that the position of the tritium label on lactic acid derived from [15-3H]retinol is on the second carbon is consistent with it coming from NADH labeled with tritium in the transferable hydrogen which was formed intracellularly during the NAD+-linked oxidation of retinol to retinaldehyde.

Animals↗
PubMed1987

Diabetes mellitus presenting as "acute osteomyelitis" of the index finger.

A case of previously undiagnosed maturity onset diabetes in a fifty-eight-year-old man with a "septic index finger" is reported. Initial X-rays showed gross destruction of the distal phalanx, suggestive of acute osteomyelitis. Control of the diabetes combined with minimal debridement of the finger resulted in healing of the lesion. X-rays taken four weeks later showed complete reconstitution of the distal phalanx, confirming the need to be conservative in the management of lesions associated with diabetes. In spite of a careful and extensive search into the literature covering unusual presentations of diabetes mellitus, the author is unable to trace a similar recorded case involving the digit of upper limb.

Diabetes Mellitus, Type 2↗
PubMed1987

Lower limb skin loss: simple outpatient management with meshed skin grafts with immediate mobilization.

Traumatic skin loss is a common problem in elderly patients presenting to an accident and emergency department. The authors report their experience with 25 patients in whom pretibial wounds were debrided, and covered with skin grafts taken under local anaesthetic and meshed by hand. All were immediately mobilized and discharged home. Healing was satisfactory in every case and there were no complications. All the patients found the treatment acceptable, and were delighted to avoid admission to hospital. This is a simple and effective outpatient procedure which can readily be carried out in the accident and emergency department.

Aged↗
PubMed1986

Local complications following intravenous benzodiazepines in the dorsum of the hand. A comparison between midazolam and Diazemuls in sedation for dentistry.

Two hundred patients requiring sedation for minor oral surgery were randomly allocated to receive either midazolam or diazepam as Diazemuls intravenously through a 23-gauge indwelling needle in the dorsum of the hand. The site of injection was inspected at 7 days and 14 days post injection and assessed for pain, tenderness, redness, induration, painless thrombosis, and thrombophlebitis. The mean dose administered was 0.119 mg/kg of midazolam and 0.298 mg/kg of Diazemuls. At 7 days there was no significant difference in venous complications. At the 14 day follow up, the midazolam group had a significantly greater incidence of tenderness and redness (p less than 0.001 and p less than 0.05 respectively using Chi squared test). The incidence of thrombophlebitis in the midazolam group was 2% at 7 days and 1% at 14 days, the corresponding figures in those given Diazemuls being none and 1% respectively. We conclude that the dorsum of the hand is a satisfactory site of injection for administration of these drugs. The higher incidence of minor complications at 14 days following midazolam was offset by its more reliable amnesic properties.

Adult↗
PubMed1986

Effect of chronic administration of excess dietary vitamin A and zinc on lipid metabolism in rats.

The effects of chronic feeding of excess dietary vitamin A and zinc on serum cholesterol, liver cholesterol and total liver lipids were studied in rats. Sixty-four Sprague-Dawley female rats were randomly allocated to 4 groups: basal diet: 4848 micrograms of vitamin A and 61 mg of Zn/kg of diet; high Zn (33-fold excess of the requirement) + basal vitamin A; basal Zn + high vitamin A (154-fold excess of the requirement) and high Zn + high vitamin A. After 120 days serum cholesterol, liver cholesterol, total liver lipids, and vitamin A and zinc in the liver and kidney were measured. The mean serum cholesterol (+/- SE) for the 4 groups were: 121 (+/- 12.6), 159 (+/- 6), 133 (+/- 7.6) and 186 (+/- 7.6) mg/dl, respectively. Liver cholesterol and total lipids for the 4 groups were determined as 1.8 (+/- 0.05), 2.2 (+/- 0.09), 4.9 (+/- 0.12) and 4.6 (+/- 0.24) mg/g of tissue and 26.3 (+/- 0.7), 26.0 (+/- 1.1), 38.9 (+/- 0.9) and 40.3 (+/- 1.4) mg/g of tissue, respectively. Liver and kidney vitamin A levels were significantly higher in group C than in group D, suggesting increased vitamin A metabolism in the high dietary zinc + high vitamin A groups. In high dietary zinc groups, a significant elevation of serum cholesterol was observed regardless of the vitamin A levels. Total liver lipids and liver cholesterol were significantly higher in rats fed high vitamin A irrespectively of the zinc levels in the diet.

Animals↗
PubMed1985

Electronegativity and hardness as coordinates in structure stability diagrams.

With electronegativity and hardness of an atom defined as 1/2(I + A) and 1/2(I - A), respectively, where I and A are the ionization potential and electron affinity, electronegativity difference and hardness sum are proposed as coordinates in structure stability diagrams. With these coordinates a successful topological classification of the crystal structures of octet and suboctet binary compounds is obtained, and a clear delineation of the structural classes portraying chemical periodicity is found.

Crystallography↗
PubMedDate not supplied

Cigarette smoking among immigrant Salvadoreans in Washington, DC: behaviors, attitudes, and beliefs.

There has been an influx of immigrants from El Salvador to the Washington, DC (DC) area, but little is known about the health behaviors of this population. This study was conducted to describe the prevalence of cigarette smoking among adult Salvadorean immigrants to the DC area. Bilingual interviewers administered a face-to-face interview to participants recruited from throughout the community. Complete data were available for 1,458 participants: 10.8% of those surveyed were current smokers and 11.7% were former smokers. Men were significantly more likely than women to have ever smoked either in the past (adjusted prevalence difference [PD = 21.0%] or currently (PD = 21.2%). The respondents tended to believe that smoking was a "habit" rather than an addition. Only 16% lived in households where smoking was permitted, and the majority supported smoke-free policies in public places, with men and current smokers being less permissive. The smoking behavior exclusively represented the smoking pattern that the Salvadoreans had adopted before immigration. The data suggest that smoking control strategies aimed at this population should seek to reduce the onset of smoking among men and continue to keep smoking among women rare.

Adult↗