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Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 1,657 records · Page 92Linked to original sources
PubMed1989

Cockroaches as vectors of pathogenic bacteria.

One hundred and thirty two cockroaches of species Blattella germanica--96 from hospital ward (test group) and 36 from residential areas (control group) were caught during Nov. 1985 to Nov. 1986. A variety of pathogenic and non-pathogenic bacteria were isolated from test and control group of insects. Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus faecalis, and Micrococci were isolated only from the test group of cockroaches. A high percentage (98.95 per cent) of test cockroaches were found to be carriers of various microorganisms as compared to the control group (80.55 per cent), the difference being statistically significant (p less than 0.001). Quantitative analysis in this study revealed that higher number of microorganisms are carried by test group of insects in the hospital environment. This, thereby suggests that these insects can play an important role in the etiology of hospital acquired infections.

Animals↗
PubMed1989

Communicating intravitreal cysticercosis.

A viable intravitreal cysticercus cellulosae communicating with subretinal space was identified in a 45-year-old man. The cyst was removed in toto via the direct scleral approach without incident. To our knowledge this is the first report of intravitreal cysticercus with subretinal extension removed successfully by the direct route. The role of careful ultrasonic scanning in cases of intravitreal cysticercosis is emphasized.

Betamethasone↗
PubMed1989

Gastric varices: profile, classification, and management.

Development of gastric varices is an important manifestation of portal hypertension. In segmental portal hypertension, gastric varices originate from short gastric and gastroepiploic veins. In generalized portal hypertension, intrinsic veins at cardia participate in the formation of gastric varices. Endoscopy and/or splenoportovenography and a high index of suspicion are required for the diagnosis of gastric varices. The incidence of gastric varices in patients with portal hypertension has been variably reported (2-70%), probably due to difficulties in diagnosis. In a small proportion of patients with gastric varices, chronic portal-systemic encephalopathy or significant variceal bleeding develops. Gastric varices can be classified, depending on their anatomical location, into gastroesophageal varices (a continuation of esophageal varices) or "isolated" gastric varices (fundal or ectopic varices). This distinction is necessary for management. Whereas surgery is recommended for bleeding fundal varices, in acute bleeding from gastroesophageal varices, sclerotherapy could be attempted successfully. In more than a quarter of patients, gastric varices disappear after obliteration of esophageal varices. Prophylactic sclerotherapy of gastric varices is not recommended.

Catheterization↗
PubMed1989

Acute pancreatitis in sickle cell crisis.

A case of acute pancreatitis, complicated by pseudocyst formation, is described in a patient with sickle cell crisis. The differential diagnosis is discussed and the literature reviewed.

Acute Disease↗
PubMed1989

Under utilization of MCH services--the major factor for very high IMR in rural Rajasthan.

Infant mortality rate (IMR) and its relation to the utilization of health services was studied in twelve villages of ICDS block Rajsamand, Rajasthan from 1st April, 1985 to 31st March, 1986. The total number of births and infant deaths were 386 and 74, respectively during one year, computing 37.44 as birth rate and 191.70 as IMR. Neonatal deaths contributed 51.4%, the most common causes of which were septicemia (28.9%), birth asphyxia (23.6%), extreme prematurity (18.4%) and tetanus neonatorum (13.1%). The common causes of deaths in post-neonatal period were pneumonia (36.1%), diarrhea (25.0%), complications of measles (16.7%) and that of pertussis (8.3%). Extreme under utilization of preventive, promotive and curative MCH services was found to be one of the major factors for very high IMR prevailing in the region.

Child Health Services↗
PubMed1989

Interaction of antitumour agent mitoxantrone with poly[d(G-C)]--a circular dichroic study.

The binding of antitumour drug mitoxantrone [1,4-dihydroxy-5, 8-bis [2-(2-hydroxy ethyl)amino)ethyl)amino)-9, 10-anthracenedione] to the synthetic polynucleotide poly[d(G-C)] was studied by circular dichroic titrations. The interaction induced intense chiroptical properties in the visible (688 nm) as well as the ultraviolet (260, 320 nm) region in an otherwise optically inactive drug. The interaction occurs in two stages, one below a drug/nucleotide ratio of 0.11 and other above this value. The second mode of interaction causes an almost cooperative enhancement of the visible induced circular dichroism (ICD).

Circular Dichroism↗
PubMed1989

Angiosarcoma of the gallbladder.

A patient with angiosarcoma of the gallbladder is presented. Occasionally, this rare malignancy is found within the abdominal cavity. However, this is only the third reported case of angiosarcoma of the gallbladder. Etiological, diagnostic, and therapeutic aspects are discussed.

Gallbladder Neoplasms↗
PubMed1989

The phenomenon of super activity in dihydrofolate reductase entrapped inside reverse micelles in apolar solvents.

Bovine liver dihydrofolate reductase has been solubilized in reverse micelles of cationic surfactant cetyltrimethylammonium bromide (CTAB) in isooctane-chloroform (1:1,V/V) mixture. Variation of waterpool (WO), pH and surfactant concentration showed that the enzyme activity was regulated by these parameters and was higher than the activity found in aqueous buffer (defined as superactivity); the maximum being at WO 13.3, pH 7.0 and CTAB concentration 75 mM. The Michaelis constants, Km for the substrate FAH2 and NADPH were found to be greater than those determined in water. Since reverse micelles have some features similar to those of biomembranes, display of super activity by dihydrofolate reductase indicates that enzymes in vivo may possess higher activity than actually observed in vitro studies in aqueous solutions.

Animals↗
PubMed1989

Role of immune serum globulin in post transfusion virus B infection.

Fifty four blood recipients were administered prophylactic immune serum globulin (31) or hepatitis B immune globulin (23) and followed up for six months. None of the patients developed either acute hepatitis B or HBsAg carrier state. However, 7 (14%) had anicteric self limiting non-B post-transfusion hepatitis. Twenty (40%) of the blood recipients developed anti-HBs during the follow up period suggesting either HBV exposure by subdetectable levels of HBsAg present either in blood or immunoglobulin preparation or due to passive transfer by administration of immunoglobulins.

Adult↗
PubMed1988

Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes.

The nucleotide sequences of the Escherichia coli genome between the glycogen biosynthetic genes glgB and glgC, and 1170 bp of DNA which follows glgA have been determined. The region between glgB and glgC contains an open reading frame (ORF) of 1521 bp which we call glgX. This ORF is capable of coding for an Mr 56,684 protein. The deduced amino acid (aa) sequence for the putative product shows significant similarity to the E. coli glycogen branching enzyme, and to several different glucan hydrolases and transferases. The regions of sequence similarity include residues which have been reported to be involved in substrate binding and catalysis by taka-amylase. This suggests that the proposed product may catalyze hydrolysis or glycosyl-transferase reactions. The cloned region which follows glgA contains an incomplete ORF (1149 bp), glgY, which appears to encode 383 aa of the N terminus of glycogen phosphorylase, based upon sequence similarity with the enzyme from rabbit muscle (47% identical aa residues) and with maltodextrin phosphorylase from E. coli (37% identical aa residues). Results suggest that neither ORF is required for glycogen biosynthesis. The localization of glycogen biosynthetic and degradative genes together in a cluster may facilitate the regulation of these systems in vivo.

Amino Acid Sequence↗
PubMed1988

Biosynthesis of bacterial glycogen. Use of site-directed mutagenesis to probe the role of tyrosine 114 in the catalytic mechanism of ADP-glucose synthetase from Escherichia coli.

Previous covalent modification studies showed that tyrosine 114 of Escherichia coli ADP-glucose synthetase is involved in substrate binding (Lee, Y. M., and Preiss, J. (1986) J. Biol. Chem. 261, 1058-1064). We have prepared, via site-directed mutagenesis, an E. coli ADP-glucose synthetase variant (Phe114) containing a Tyr114 to Phe substitution in order to test whether the phenolic hydroxyl group plays a critical role in catalysis. Kinetic characterization of Phe114 ADP-glucose synthetase indicates that the Tyr114 hydroxyl is not obligatory for the enzyme catalysis. However, the variant enzyme showed altered properties. It showed a decreased apparent affinity for the substrates. The variant enzyme showed less than 2-fold activation by 5 mM fructose 1,6-bisphosphate in the ADP-glucose synthesis direction. In contrast, in the pyrophosphorolysis direction, the mutant enzyme showed about a 30-fold activation by 5 mM fructose 1,6-bisphosphate. The variant enzyme is heat-labile compared to wild type enzyme. It lost about 60% enzyme activity on incubation at 65 degrees C for 5 min in the presence of 30 mM Pi. The wild type enzyme is stable under these conditions. The results indicate that tyrosine 114 is involved directly or indirectly in enzyme catalysis, but is not obligatory for the enzyme catalysis. Conversion of Tyr114 to Phe also alters the regulatory properties of the enzyme with respect to activation by fructose-1,6-P2 and inhibition by AMP.

Enzyme Stability↗
PubMed1988

Reconstituted U1 small nuclear ribonucleoprotein complex restores 5' splice site cleavage activity.

Functional reconstitution of U1 small nuclear ribonucleoprotein particle (U1 snRNP) was performed using in vitro transcribed U1 snRNA. Hela cell nuclear extract was depleted of its constituent snRNPs by centrifugation at 100,000 X g. The supernatant was devoid of snRNAs and lacked cleavage activity in splicing reactions using in vitro transcribed beta-globin pre-mRNA as substrate. The resulting pellet which contained the snRNAs, retained 5' splice site cleavage activity in a similar splicing reaction. Supplementation of the inactive supernatant fraction with in vitro transcribed U1 snRNA, partially restored 5' splice site cleavage activity thereby demonstrating the specific requirement of U1 snRNP in the initial stage of pre-mRNA splicing.

Cell Nucleus↗
PubMed1988

A rapid procedure for the isolation of phycobilisomes from cyanobacteria.

This paper describes a method for the rapid isolation of phycobilisomes using a cationic detergent, CTAB (cetyltrimethylammonium bromide). The method has distinct advantages over those currently in use in that (i) release of intact phycobilisomes from cells in the presence of CTAB occurs in 40 s (as compared to 40-60 min of incubation required with Triton X-100), thereby reducing the chances of proteolysis of the component phycobiliproteins; and (ii) these phycobilisome preparations have reduced chlorophyll contamination in the initial stages. In addition this method also helps retain the structural and functional properties, as evidenced by spectroscopy and sodium dodecyl sulfate-polyacrylamide gel analysis.

Cell Membrane↗