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Biomedical subjects

P Kumar

Publications and source records attributed to P Kumar.

At least 523 records · Page 29Linked to original sources
PubMed1992

Altered host resistance to Listeria monocytogenes in mice exposed to 1-chloroacetophenone (CN) vapours.

Short term repeated exposure of 1-chloroacetophenone (CN) vapours at a concentration of 0.153 mg per litre for 15 minutes daily on 10 consecutive days in Swiss albino male mice resulted in increased mortality to Listeria monocytogenes. Significantly elevated bacterial growth was observed in the spleen and liver of the CN exposed animals. The increased bacterial count in these organs was evident within 4-6 days post challenge as compared to vehicle exposed infected and unexposed infected animals. Increased susceptibility to infection has been considered to be the function of immune alteration due to cumulative short term effects of CN vapour inhalation. This may be attributed to immunotoxic effects of CN on T-cells mediated macrophage functions.

Animals↗
PubMed1991

A general method for the synthesis of 3'-sulfhydryl and phosphate group containing oligonucleotides.

The syntheses are described of polymer supports useful for the synthesis of 3'-partially protected sulfhydryl, free sulfhydryl or phosphate group containing oligonucleotides. The supports are compatible with established phosphoramidite chemistry of oligonucleotide synthesis giving rise to oligonucleotides with terminal 3'-partially protected sulfhydryl, free sulfhydryl or phosphate function during final deprotection. Crosslinking of the thiol group containing oligonucleotide to sulfhydryl group specific fluorescent probes was carried out with high selectivity, in high yields under mild conditions. 3-Aminopropylated Controlled Pore Glass (CPG) was succinylated with succinic anhydride followed by the reaction with S-(2-thio-5-nitropyridyl)-2-mercaptoethanol in the presence of dicyclohexylcarbodiimide (DCC). The resultant polymer support was reacted with 4,4'-dimethoxytrityloxyalkanthiol 5(a - c) to yield the derivatized polymer supports 5(a - c). The support 5a directly leads to oligonucleotide-3'-phosphate on deprotection with ammonical DTT at 55 degrees C while the supports 5b and 5c lead to oligonucleotide-3'-thiols or partially protected 3'-sulfhydryl group containing oligonucleotides during final deprotection.

Base Sequence↗
PubMed1991

Superoxide dismutase activity regulation by spermine: a new dimension in spermine biochemistry and sperm development.

Amines are a group of highly important compounds of biological importance; they are known promoters of cell growth, can complex with nucleic acids and can stimulate DNA-primed RNA polymerase activity. Spermine, a polyamine abundantly present in the secretions of the male accessory sex organs, has received no functional attributes till date. This study had been a pioneer attempt to validate the hypothesis of a metalloenzyme activity modulation by spermine and implicit correlations have been drawn.

Animals↗
PubMed1991

Superoxide dismutase activation in thyroid and suppression in adrenal. Novel pituitary regulatory routes.

This study reports that administration of TSH in young female mice results in a concomitant augmentation of SOD activity in the thyroid gland. A strong thyroid-adrenal interdependence was also evident in the form of a marked loss of SOD activity in the adrenal gland in response to TSH administration. Very recently SOD/O2.- system had been identified as a potent H2O2 generator which provides substrate for the action of key enzyme in thyroxine and progesterone biosynthesis, viz. the peroxidase. Thus, these results strongly suggest that trophic hormones tonically stimulate hormone biosynthesis by modulating activation/suppression of specific enzymes, which could be the basis of the tuning sequence.

Adrenal Glands↗
PubMed1991

Immunoglobulin heavy chain constant-region gene polymorphism in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is associated with immunoglobulin allotypes in several ethnic groups. In this study, we investigated the association of a Bst EII immunoglobulin heavy chain constant-region gene restriction fragment length polymorphism with SLE in patients from the US and Mexico. A 3-kb restriction fragment was observed with significantly decreased frequency in randomly selected Mexican SLE patients and in Mexican SLE patients in multiplex families. However, no such association was observed in SLE patients from the US. Thus, the absence of a 3.0-kb Bst EII restriction fragment from immunoglobulin heavy chain constant-region genes provides a marker for SLE in Mexican individuals.

Blotting, Southern↗
PubMed1991

Poly(vinyl alcohol) hydrogel as an artificial articular cartilage: evaluation of biocompatibility.

We have developed a new poly(vinyl alcohol) hydrogel (PVA-H) of increased physical strength through a new manufacturing process. Its mechanical properties have been found to be preferable as a substitute for articular cartilage. To evaluate its biocompatibility as an artificial articular cartilage, a series of in vivo tests within the intraarticular, as well as the intramuscular, environment were conducted. Tissue reactions of cartilage, bone, synovium, and muscle to PVA-H were studied histologically. In the experimental group, in which PVA-H was implanted, inflammatory reactions of all of these tissues were very slight. In the control group, in which ultra-high molecular weight polyethylene (UHMWPE) was implanted, although tissue reactions of bone and muscle were as slight as in the experimental group, those of cartilage and synovium were somewhat more conspicuous. By way of these findings, the better biocompatibility of PVA-H was documented.

Animals↗
PubMed1991

Low wear rate of UHMWPE against zirconia ceramic (Y-PSZ) in comparison to alumina ceramic and SUS 316L alloy.

Partially stabilized zirconia ceramic is being recognized among ceramics for its high strength and toughness. With this ceramic, is possible to manufacture a 22-mm-size femoral head for low friction arthroplasty of the hip joint in association with an ultra-high-molecular-weight polyethylene socket. Wear-resistant properties of zirconia ceramic were screened on two principally different wear devices. Sterile calf bovine serum, physiological saline, and distilled water were chosen as the lubricant fluid media. Depending on the lubricant medium, the wear factor of polyethylene against zirconia ceramic counterfaces was 40 to 60% less than that against alumina ceramic counterfaces, and 5 to 10 times lower than with the SUS316L metal counterfaces. Polyethylene wear against metal was more susceptible in saline in which it had 2 to 3 times higher wear rate than with serum. On the other hand, different fluid media had little effect on polyethylene wear against ceramic counterfaces. In each set of tests, the wear factor obtained on an unidirectional wear device showed 10 to 15 times higher values, in comparison to the wear factor estimated on a reciprocating wear device.

Alloys↗
PubMed1991

The dartos musculocutaneous flap.

Six dartos musculocutaneous flaps have been used to resurface proximal penile defects. The vascular anatomy of the flap, surgical technique and complications are described in detail.

Adult↗
PubMed1991

Human immunodeficiency virus infection of enterocytes and mononuclear cells in human jejunal mucosa.

Intestinal malabsorption is a recognized cause of malnutrition in patients infected with human immunodeficiency virus. However, the relationships among human immunodeficiency virus infection, morphological changes in the intestine, and development of intestinal malabsorption are not well established. Nine patients infected with human immunodeficiency virus underwent tests of intestinal absorption and jejunal biopsies for morphometric measurements, enzyme assays, and virus detection by in situ hybridization. Steatorrhea and low lactase activities were found in more than 85% of the patients. All biopsy specimens were abnormal with reversal of the ratio of villus length to crypt depth in seven and enlarged enterocyte nuclear size in nine. Human immunodeficiency virus was detected in five jejunal biopsy specimens, within villus enterocytes of one patient who had the most severe malabsorption of the group and in four other biopsy specimens in mononuclear infiltrating cells of the lamina propria. These results suggest that human immunodeficiency virus infection of the small intestinal mucosa is an early event that is associated with altered enterocyte differentiation and function.

Acquired Immunodeficiency Syndrome↗
PubMed1991

DR3 and nonDR3 associated complement component C4A deficiency in systemic lupus erythematosus.

The molecular basis of complement component C4A deficiency in white U.S. and Mexican patients with systemic lupus erythematosus (SLE) was studied. Genomic DNA from SLE patients and non-SLE controls was analyzed for restriction fragments using HindIII and a 5' C4 cDNA probe. C4A gene deletion was recognized by the loss of a 15-kb restriction fragment and the appearance of a 8.5-kb fragment. Thirty-two selected U.S. SLE patients, 7 nonSLE controls, and 11 Mexican SLE patients and 9 relatives were studied. The deletion was recognized in all of the 14 HLA-B8;DR3 SLE patients with a C4A protein deficiency. Two SLE patients with DR3 but without B8 also had this gene deletion. None of the 3 U.S. SLE nonDR3, C4A protein deficient patients nor 20 C4A protein deficient Mexican individuals (11 SLE patients and 9 relatives; none had B8 and/or DR3) showed this deletion. Thus the C4A gene deletion failed to account for the C4A protein deficiency in all the nonDR3 Mexicans and in some U.S. SLE patients. To determine whether gene conversion at the C4A locus would encode a C4B-like protein and be responsible for the C4A protein deficiency (in nonDR3 patients), the C4d region of the gene was amplified by polymerase chain reaction and subjected to Nla IV digestion, and restriction fragment analysis was performed using a C4d region-specific probe. The resulting restriction fragment length polymorphism pattern revealed no changes in the isotype-specific region of the gene as characterized by C4A-specific 276- and 191-bp fragments in Dr3 or nonDR3 individuals. Thus, homoexpression of C4B at both loci was not responsible for C4A deficiency in nonDR3 SLE patients without C4A gene deletion.

Alleles↗
PubMed1991

Radiographic pulmonary abnormalities after different types of cardiac surgery.

One aim of this study was to determine the incidence of new radiographic pulmonary abnormalities during hospitalization after cardiac surgery. Another aim was to determine if such abnormalities are more common among patients who had left internal mammary artery (LIMA) grafting. The predictive value of radiographic abnormalities for clinically important pulmonary morbidity was also determined. The anteroposterior chest radiographs of 152 patients obtained by portable equipment were evaluated to determine the incidence of new postoperative radiographic pulmonary abnormalities such as atelectasis, consolidation, infiltrate, and pleural effusion. Clinically important pulmonary morbidity was defined as a delay in tracheal extubation or discharge from the hospital because of a pulmonary reason. Among the 89 patients who had LIMA grafting and left pleurotomy, there was an 88% incidence of left-sided pulmonary abnormalities; a 73% incidence of left-sided atelectasis; and a 55% incidence of left-sided effusion. Among the 63 patients who had saphenous vein grafting only and/or valvular surgery, the respective incidences were 68%, 54%, and 35%, which were lower (P less than or equal to 0.05) than those in the patients who had LIMA grafting. There was no significant difference in abnormalities between the saphenous vein grafting and the valvular surgery groups. The 35% incidence of left-sided pleural effusion when LIMA grafting and pleurotomy were not performed was unexpectedly high. There was no association between radiographic abnormalities and age, the duration of cardiopulmonary bypass, and the duration of aortic occlusion, indicating that cardiopulmonary bypass was not a primary etiology of these radiographic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗