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Biomedical subjects

S Basu

Publications and source records attributed to S Basu.

At least 451 records · Page 25Linked to original sources
PubMed1982

Increased activity of a beta-galactosyltransferase in tissues of rats bearing prostate and mammary adenocarcinomas.

The levels of UDP-galactose: N-acetylglucosamine(beta 1-4)galactosyltransferase activity (GalT-4) were determined in the sera, in solid tumors, and in corresponding cell cultures of rats bearing two lines of prostate adenocarcinomas (PA-2 and PA-3), and in the sera of rats bearing other transplanted and autochthonous adenocarcinomas. Sera and tissues from normal (tumor-free) rats were used as controls. Prostate adenocarcinoma cell cultures had five times greater levels of enzyme activity than did tumor cell infiltrated lymph nodes from animals bearing the prostate adenocarcinomas. The levels of activity in the cells of both prostate tumor lines were equivalent, even though they metastasize through different routes. Serum levels of galactosyltransferase activity were detected in the blood, and in rats bearing a mammary adenocarcinoma with extensive necrosis of the tumor mass (tumor mass greater than 22.0 g/200 g body weight). The increase was three times the control value. The sera of L-W rats bearing prostate tumors (PA-2 and PA-3) were inactive with the GalNAc-containing acceptor, Gm2 (GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc-Cer) but active with either free GlcNAc (Km = 0.25 mM) or LcOse3Cer (GlcNAc beta 1-3 Gal beta 1-4Glc--Cer; GlcNAc--R).

Adenocarcinoma↗
PubMed1981

Interaction of mammalian hemoglobins with dehydroascorbic acid.

Reactive sulfhydryl groups of major hemoglobins from guinea-pig, rat and cat reduced dehydroascorbic acid to ascorbic acid leading to formation of intrachain disulfide bonds. Hybridization experiments indicated that the reduction was carried out by the alpha chain of cat hemoglobin.

Animals↗
PubMed1981

Ascorbic acid metabolism in diabetes mellitus.

In contrast to normal subjects diabetic patients and very low plasma ascorbic acid and significantly high (p less than 0.001) dehydroascorbic acid irrespective of age, sex, duration of the disease, type of treatment, and glycemic control. However, there was no significant difference between the mean leukocyte ascorbate concentrations of the two populations. The in vitro rates of dehydroascorbate reduction in the hemolysate and the erythrocyte reduced glutathione levels and the glucose-6-phosphate dehydrogenase activities, which regulate the dehydroascorbate reduction, were similar in normal and diabetic subjects. The turnover of ascorbic acid was higher in the diabetics than that in the normal volunteers. Experiments with diabetic rats indicated that the increased turnover of ascorbic acid was probably due to increased oxidation of ascorbate to dehydroascorbate in tissue mitochondria. Ascorbic acid supplementation at a dose of 500 mg per day for a brief period of 15 days resulted in an increase in the plasma ascorbate level temporarily, but it did not lower the blood glucose level of the diabetic patients.

Adolescent↗
PubMed1981

Location, function, and nucleotide sequence of a promoter for bacteriophage T3 RNA polymerase.

The major promoters for bacteriophage T3 RNA polymerase on the T3 genome have been mapped by DNA.RNA filter hybridization. One promoter is located in a 300-base-pair Hpa I restriction fragment near the genetic "left" end of T3 DNA. The sequence in the vicinity of the major initiation site of transcription in this region has been determined. A part of the (-)strand sequence is 5' T-A-T-T-T-A-C-C-C-T-C-A-C-T-A-A-A-G-+1 G-G-A-A-U 3'. Comparison of this sequence with the prototype 23-base-pair promoter sequence for bacteriophage T7 RNA polymerase shows a striking pattern of homology and divergence. Between positions -9 and +4, the sequences are virtually identical, whereas between positions -17 and -10, the sequences are quite different. It is postulated that these sequence subsets may perform different functions in transcription initiation by the phage RNA polymerases.

Base Sequence↗
PubMed1981

Differential inhibition of multiple forms of DNA polymerase alpha from IMR-32 human neuroblastoma cells.

Three forms of DNA polymerase (pol) alpha from human neuroblastoma IMR-32 were separated by DEAE column chromatography. All sedimented at approximately 7 S in 5-20% continuous sucrose density gradients. All were heat labile, with pol alpha 2 the most (90% inactivated) and pol alpha 3 the least (50% inactivated) sensitive to heating for 5 min at 50 degrees C. pol alpha 1 and alpha 2 efficiently utilized activated calf thymus DNA as template. The most active form, pol alpha 2, used both poly(dA).(dT)12-18 and poly(dT).(dA)12-18 as template at equal rates. Differential inhibition of DNA polymerase alpha activities was examined in the presence of ricin, hemin, and a nonhistone chromatin protein. All three polymerases were inhibited by both ricin (nonreduced) and hemin, with pol alpha 2 the most (80-90%) and pol alpha 3 the least (60%) sensitive in each case. In contrast, only pol alpha 2 and alpha 3 activities were inhibited (80-85%) by rat liver nonhistone chromatin protein.

Animals↗
PubMed1981

Geographical distribution and epidemiological incidence of phage-types of Salmonella weltevreden in India during 1958-1974.

Phage-typing of Salmonella weltevreden was carried out with a set of 6 typing phages and the geographical distribution of 946 strains isolated during 1958-1974 studied. Phage-type 5 was the most predominant type and types 2 and 7 were found exclusively in India. Strains isolated from epidemics and epizootics were studied to assess the epidemiological significance and utility of the scheme based on the set of six typing phages. Phage-types from various sources in different geographical regions were studied with reference to the incidence in man.

Animals↗
PubMed1980

Sub-classification of phage types of Salmonella weltevreden and typing of strains by an extended phage typing scheme.

By the use of two adapted phage preparations of Typing phage II the S. weltevreden phage types 4 and 5 could be classified into two sub-types each and phage types 9 and 10 into three sub-types each. the 1094 strains of S. weltevreden could be classified into a total of sixteen phage types including the sub-types. The host range mutants of Typing phage II were distinct from the parent strain. After adaptation to two insensitive strains, one of the new preparations, phi IIA lost its affinity to some strains which were lysed by the parent phage strain but gained lytic affinity for a few others that were originally insensitive. The second preparation phi IIB showed an increase in lytic range as expected. Antigenically these preparations were shown to be related but not identical. The possible reasons for serological non-identity of host range mutants with the parent strain have been discussed.

Bacteriophage Typing↗
PubMed1979

Superstructures of wet inactive chromatin and the chromosome surface.

Superpacking of chromatin and the surface features of metaphase chromosomes have been studied by SiO replication of wet, unstained, and unfixed specimens in an exceedingly thin (less than or equal to nm) aqueous layer, keeping them wet. Hydrophilic Formvar substrates allow controlled thinning of the aqueous layer covering the wet specimens. Whole mounts of chromatin and chromosomes were prepared by applying a microsurface spreading method to swollen nuclei and mitotic cells at metaphase. The highest level of nucleosome folding of the inactive chromatin in chicken erythrocytes and rat liver nuclei is basically a second-order superhelical organization (width 150--200 nm, pitch distance 50--150 nm) of the elementary nucleosome filament. In unfavorable environments (as determined by ionic agents, fixative, and dehydrating agetns) this superstructure collapses into chains of superbeads and beads. Formalin (10%) apparently attacks at discrete sites of chromatin, which are then separated into superbeads. The latter consist of 4--6 nucleosomes and seemingly correspond to successive turns of an original solenoidal coil (width 30--35 nm), which forms the superhilical organization. When this organization is unfolded, eg, in 1--2 mM EDTA, DNAse-sensitive filaments (diameter 1.7 nm) are seen to be wrapped around the nucleosomes. The wet chromosomes in each metaphase spread are held to each other by smooth microtubular fibers, 20--20 nm in diameter. Before they enter into a chromsome, these fibers branch into 9--13 protofilaments, each 5 nm wide. The chromosome surface contains a dense distribution of subunits about 10--25 nm in diameter. This size distribution corresponds to that of nucleosomes and their superbeads. Distinct from this beaded chromosome surface are several smooth, 23--30-nm-diameter fibers, which are longitudinal at the centromere and seem to continue into the chromatid structure. The surface replicas of dried chromosomes do not show these features, which are revealed only in wet chromosomes.

Animals↗
PubMed1979

Bacteriophage typing of Salmonella weltevreden.

Salmonella weltevreden has been found to be one of the commonest Salmonella serotypes isolated from diverse sources in India and has also been isolated in a number of other countries. A phage typing scheme was developed for this serotype using a set of six typing phages. These phages had been selected out of 146 phage strains isolated and purified from stool samples of man, laboratory animals and other animals, sewage and surface water sources, and the lytic mutants of temperate phages form S. weltevreden. The phage typing scheme was applied systematically to type the 946 strains from India isolated during 1958-1974 and 148 strains originating from Australia, Burma, England, Gan Island, Holland, Hong Kong, Malaysia, New Zealand, Papua New Guinea, The Philippines, Thailand, The United States and Vietnam during 1953-1971. The scheme was particularly studied to evaluate its utility in mapping the epidemiologically related strains from various sources. The S. weltevreden strains could be classified into ten phage types. Phage types 2 and 7 were found exclusively amongst Indian strains, type 6 from Vietnam and type 8 from Burma, Thailand and Vietnam. Phage types were found to be stable and consistent with the independent epidemiological data available.

Bacteriophage Typing↗
PubMed1979

Inhibition of human neuroblastoma DNA polymerase activities by plant lectins and toxins.

The effects of concanavalin A and ricin (RCAII, Mr 65,000) on [3H]thymidine incorporation into human neuroblastoma IMR-32 DNA showed reduction of total DNA synthesis to 50% and 70% of control, respectively. Two DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7.) activities (alpha and beta) involved in the biosynthesis in vitro of DNA were separated by sucrose density gradient centrifugation from IMR-32 cell homogenate. The DNA polymerase alpha activity was also purified by selective precipitation with polyethylene glycol (Mr 6000) followed by agarose-concanavalin A column chromatography. The activities of both DNA polymerases were examined at various concentrations of mutagenic and nonmutagenic plant agglutinins and the toxin ricin. Concanavalin A and ricin specifically inhibited DNA polymerase alpha activity (activity reduced to 19% and 10%, respectively), whereas DNA polymerase beta activity was inhibited (reduced to 16%) by red kidney bean agglutinin (PHA-P).

Cell Line↗