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Biomedical subjects

S K Jain

Publications and source records attributed to S K Jain.

At least 19 recordsLinked to original sources
PubMed1992

Putative three-stranded DNA pairing intermediate in recA protein-mediated DNA strand exchange: no role for guanine N-7.

As an early step in DNA strand exchange reactions, the recA protein aligns homologous sequences within two DNA molecules to form a putative triple-stranded intermediate. In virtually all models for three-stranded DNA proposed to date, hydrogen bonds involving the N-7 position of guanine have played a prominent structural role. To determine whether the N-7 position of guanine is required for triple helix and heteroduplex formation in the recA protein-mediated DNA pairing reaction, guanine was completely replaced by the base analog 7-deazaguanine in both strands of the duplex DNA substrate using polymerase chain reaction. This modified double-strand DNA was reacted with unmodified single-strand DNA in vitro. The 7-deazaguanine-substituted DNA functioned as well as the unsubstituted DNA in recA protein-mediated DNA three-strand exchange reactions. Strand exchange reactions involving four strands also proceeded normally when three of the four strands contained 7-deazaguanine rather than guanine. In fact, the rate of strand exchange improved somewhat when the modified DNA substrates were used. This indicates either that the N-7 position of guanine is not essential for the formation of the putative triple-stranded DNA pairing intermediate, or that a three-stranded (or four-stranded) structure is not an obligate intermediate in recA protein-mediated DNA strand exchange.

Base Sequence↗
PubMed1992

Traumatic intrapericardial diaphragmatic hernia.

Traumatic intrapericardinal diaphragmatic hernia is a rare occurrence following blunt thoracoabdominal injuries. We have reviewed 59 cases reported in the literature and added three. Emphasis is placed on the diagnostic difficulties encountered, with some discussion regarding the management and surgical approach.

Accidents, Traffic↗
PubMed1992

The effect of glycemic control and duration of diabetes on cholesterol and phospholipid classes in erythrocytes of type I diabetes.

Abnormalities in the lipid composition of erythrocytes can alter blood rheology and viscosity. These alterations have been implicated in the pathogenesis of microvascular disease in diabetic patients. The present study was undertaken to examine whether or not long-term glycemic control or duration of diabetes has any role in the altered membrane cholesterol and phospholipid composition of erythrocytes in type I diabetes. Long-term glycemic control was assessed by measuring glycosylated hemoglobin (GHb) from diabetic patients and age-matched normal volunteers. There was no significant correlation between GHb or duration of diabetes with total cholesterol, phospholipid, and cholesterol to phospholipid molar ratios in erythrocytes of these patients. Among phospholipid classes, GHb showed a significantly negative relationship with sphingomyelin (SM) (r = .55, P less than .01) levels, but was not related to phosphatidylcholine (PC) and phosphatidylethanolamine (PE) levels of erythrocytes. Duration of diabetes had no effect on SM, PC, or PE levels of erythrocytes.

Adolescent↗
PubMed1992

Sporostatic effect of some oils against fungi causing otomycosis.

In vitro animycotic effect of mustard, groundnut, soybean, coconut and amla oils on five fungi i.e., Aspergillus niger, A. flavus, Absidia corymbifera, Penicillium nigricans and Candida albicans isolated from otitic fungal infection of external ear (Tympanic membrane) of human being was studied. Spore germination was evaluated in the oil samples as such after heating for two minutes & after boiling the oil. Data show that mustard and coconut oil seem to be effective as in these the spore germination was poor. Other oils were not found to be much effective. Sporostatic effect was noted only when the oils were used after heating or boiling this may be correlated by the synthesis of enzymes during spore germination.

Antifungal Agents↗
PubMed1992

Functional hypothalamic amenorrhoea-isolated gonadotropin deficiency.

A 21 year old female patient with primary amenorrhoea was diagnosed to have isolated gonadotropin deficiency with probable functional hypothalamic amenorrhoea. The evaluation included buccal smear for sex chromatin, trial of medroxy-progesterone acetate, trial of oestrogen-progesterone preparation and estimation of serum prolactin, gonadotrophin and oestrogen levels. When diagnosed as isolated gonadotropin deficiency, treatment with gonadotropin is rewarding.

Adult↗
PubMed1992

Cloning and nucleotide sequencing of sheep growth hormone cDNA.

cDNA was prepared from the mRNA isolated from sheep anterior pituitary glands. On cloning cDNA in E. coli, a clone coding full sequence of sheep pre-growth hormone was determined. The sequence for the sheep growth hormone (GH) is in agreement with the amino acid sequence of the protein determined previously except for the asparagine residue at position 99 rather than aspartic acid and the arginine residue at position 146 in place of threonine. The cDNA sequence presented is also in accordance with the genomic sequence for the sheep GH gene that has been reported.

Amino Acid Sequence↗
PubMed1992

Pharmacokinetics and urinary excretion of sulfadiazine in buffalo calves.

Pharmacokinetics and urinary excretion of sulfadiazine were determined in buffalo calves following single oral administration (150 mg/kg). Kinetic evaluation of plasma levels was performed using a 2-compartment model. The absorption half-life and elimination half-life were 3.41 +/- 0.63 and 13.75 +/- 1.94 h, respectively. Based on this study, an optimal dosage regimen of sulfadiazine in buffalo calves would be 165 mg/kg, followed by 75 mg/kg at 12-h intervals. Sulfadiazine was mainly excreted in the urine as free amine, while the percentage of acetylated sulfadiazine was comparatively low.

Absorption↗
PubMed1991

Plasma lecithin-cholesterol acyltransferase activity and cholesterol and phospholipid levels in premature newborn infants.

Lecithin-cholesterol acyltransferase (LCAT) activity has been suggested to play an important role in the regulation of lipid metabolism. The present study was undertaken to examine any relationship between LCAT activity and altered cholesterol levels in plasma of full-term and preterm newborn infants. Plasma total, free and esterified cholesterol, total phospholipid and LCAT activity (cholesterol esterified, nmol/ml per h) were determined in placental cord blood. There was a significant negative relationship between total cholesterol levels and gestational age. The increased cholesterol with prematurity was due to both free and esterified cholesterol. There was also a significant negative relationship between LCAT activity and free cholesterol levels but not between LCAT activity and total cholesterol and esterified cholesterol levels. There was no relationship between esterified-to-free cholesterol ratio and LCAT activity. Total phospholipid was not significantly related to either gestational age or LCAT activity. This study suggests that reduced LCAT activity may be one of the factors that result in the accumulation of cholesterol in premature infants.

Cholesterol↗
PubMed1991

Processing of the p62 envelope precursor protein of Semliki Forest virus.

The spike protein of Semliki Forest virus is composed of three subunits, E1, E2, and E3, which mediate the fusion of the virus membrane with that of the host cell. E2 and E3 are synthesized as a precursor, p62, which is cleaved post-translationally after an Arg-His-Arg-Arg sequence. In vitro mutagenesis of a cDNA clone of the spike proteins was used to specifically alter amino acids in this cleavage site. Cleavage of p62 was completely blocked by mutation of the proximal Arg residue to Phe, without affecting transport or surface expression of the spike protein. The cleavage mutation resulted in the loss of spike protein fusion activity within the physiological pH range. Fusion activity was restored by cleavage with exogenous chymotrypsin and showed the same low pH dependence as that of wild type. The cleavage sensitivity of newly synthesized p62 was investigated by pulse-chase analysis and chymotrypsin treatment in detergent solution. p62 was sensitive to cleavage immediately following its synthesis. Protein trapped in the rough endoplasmic reticulum or Golgi apparatus by carbonyl cyanide m-chlorophenylhydrazone, monensin, or Brefeldin A treatment was also fully sensitive to cleavage. These results suggest that p62 does not require an organelle-mediated conformational change for processing. Thus, in vivo, the site of p62 processing is probably controlled by the location or activity of the cleavage enzyme, rather than the sensitivity of the p62 substrate.

Amino Acid Sequence↗
PubMed1991

Syringohydromyelia: radiological evaluation of 82 patients in a developing country.

A series of 82 patients presenting with syringohydromyelia and confirmed at operation were studied by conventional radiological techniques and computed tomography (CT). Cord collapse was demonstrated in 71% of the patients with wide bony canals and only 11% of patients with normal bony canals. It was most reliably shown with high resolution CT. Intrathecal CT metrizamide myelography (CTMM) failed to demonstrate contrast percolation into many cavities shown in the plain scans. Obliteration of the subarachnoid space at C1-2 levels appreciated in the plain scans strongly indicated coexisting tonsillar herniation, making CTMM unnecessary. In almost all patients, CTMM was found to be non-contributory if the high resolution plain CT scan failed to reveal cord cavitation.

Adolescent↗
PubMed1991

Enhancing effect of a choline-deficient diet on alterations of hepatic drug-metabolizing enzymes in hepatitis- and hepatoma-predisposed rats (LEC rats).

Marked alterations of hepatic drug-metabolizing enzymes were observed in hepatitis- and hepatoma-predisposed rats (LEC rats) fed a choline-deficient diet. The diet enhanced the development of hepatitis with severe jaundice. The levels of two major classes of cytochrome P-450, P-450PB and P-450MC, were markedly decreased. GST-Yp was dramatically increased, whereas GST-Ya, Yb1 and Yb2 were decreased. LEA rats (the control rats to LEC) fed a choline-deficient diet mimicked LEC rats fed a normal diet in terms of the above enzyme alterations, indicating that hypomethylation is involved in the pathogenesis of hepatitis and hepatoma in LEC rats. Such hypomethylation may initiate the hepatocytes that spontaneously develop hepatitis and hepatoma.

Animals↗
PubMed1991

Aluminum uptake and toxicity in cultured mouse hepatocytes.

Hepatic aluminum (Al) accumulation in association with hepatobiliary dysfunction has been described in children receiving contaminated parenteral alimentation solutions and in aluminum-overloaded experimental animals. The mechanisms of hepatic Al uptake are not clearly understood, and it is not known whether Al is directly toxic to the hepatic cell or if toxicity occurs from the effect of Al on hepatic iron (Fe) metabolism. Al causes a microcytic hypochromic anemia and concomitant hepatic Al and Fe can accumulate in dialysis patients, suggesting that Al may alter Fe metabolism. Therefore, Al uptake and toxicity were studied in mouse hepatocytes in culture. Al accumulation, cell growth, media hepatic enzyme concentrations, and cell malonyldialdehyde concentrations, a marker of membrane lipid peroxidation, were measured in mouse hepatocytes grown in media containing either Al citrate, transferrin-Al (Tf-Al), or no additions over 96 h. Al uptake occurred only in cells grown in Tf-Al and Al citrate at 24 h and increased linearly achieving cellular concentrations at 96 h of 522 +/- 36 and 186 +/- 12 micrograms/L, respectively, compared with 31 +/- 3 micrograms/L (P less than 0.001) in control media. Inhibition of cell growth occurred at 48, 72, and 96 h (P less than 0.001), and media lactate dehydrogenase and aspartate aminotransferase concentrations increased starting at 48 and 72 h, respectively (P less than 0.001), only in media containing Tf-Al. Cell malonyldialdehyde levels were significantly higher in Tf-Al-loaded mouse hepatocytes compared with control cells at 96 h (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1991

Reduced vitamin E and increased lipofuscin products in erythrocytes of diabetic rats.

Vitamin E deficiency in erythrocytes causes decreased cell survival, hypercoagulability, and increased adhesiveness to the endothelium. Similar abnormalities are found in erythrocytes of the diabetic population. This study examines the effect of diabetes on vitamin E and lipofuscin products (aging pigments) in erythrocytes of streptozocin-induced diabetic rats. Controls were injected with buffer alone, and a subgroup consisting of insulin-treated diabetic rats were injected daily with insulin for 2 mo. Mean +/- SD vitamin E levels were 23.2 +/- 4.9, 19.4 +/- 3.2, and 25.9 +/- 2.5 nmol/mumol phospholipid. Lipid fluorescence values (relative values/phospholipid) were 11.1 +/- 1.9, 14.1 +/- 2.6, and 11.9 +/- 1.8 (excitation/emission 360/440 nm) in control, diabetic, and insulin-treated diabetic rats, respectively. Differences in vitamin E and lipofuscin products were significant between all control and diabetic groups and diabetic and insulin-treated diabetic groups. Reduction in vitamin E and increases in lipofuscin products in diabetic rats were significant even when values were expressed per micromole Hb or per 100 ml erythrocytes. This study demonstrates that hyperglycemia significantly reduces vitamin E and increases lipofuscin products in erythrocytes of diabetic rats. These effects were prevented with insulin treatment.

Animals↗
PubMed1991

A clinico-radiological study of secondary mycoses in pulmonary tuberculosis.

Clinical and radiological differences were compared in Fungus positive (74) and negative (66) cases of pulmonary tuberculosis. Cough, expectoration, dyspnoea, and fever were marked in former group than that of latter. Anaemia, leucocytosis, raised ESR, abnormal radiological shadows and mycetoma in healed cavity were also noted in significant number in fungus positive cases.

Calcinosis↗