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Biomedical subjects

R Basu

Publications and source records attributed to R Basu.

At least 55 records · Page 3Linked to original sources
PubMed1994

Humoral immunity response in malignancies with special reference to the effect of radiotherapy.

In view of the variability in the findings recorded by different authors in the level of immunoglobulins in patients suffering from malignancies, a study on 34 cases of six types of malignancies treated with radiotherapy (telecobalt and telecesium) was carried out to record the humoral response and also to compare the response during radiotherapy and after radiotherapy in these cases. Serum of 20 age-matched normal volunteers served as normal control. The study recorded that the pretherapy levels of IgA and IgG were raised in most of the cases; but the IgM was decreased than that of the control level. This is probably due to the fact that the selective clones of cells producing different types of immunoglobulins are responding to the malignancies in different ways. The midtherapy level of all immunoglobulins showed the value lower than the pretherapy level, but recovery was observed in the post-therapy period with all immunoglobulins in all the cases irrespective of the histological types of malignancies. It was also apparent from this study that the post-therapy gain in the level of immunoglobulins over midtherapy level was more pronounced in cases having telecobalt therapy. Assessment of humoral response in 25 patients suffering from squamous cell carcinoma of different grades revealed that the midtherapy fall and subsequent post-therapy gain had no definite correlation with grading.

Adult↗
PubMed1993

A fluorescence anisotropy study of stabilizing effect of tri- and tetra- nitrovasodilatory drugs on DPPC liposomal membrane.

Glyceryl trinitrate (GT) and pentaerythritol tetranitrate (PT) are two vasodilatory drugs. The physical properties of the membrane lipid matrix, which determine the structure and function of the membrane-bound proteins, generally control the perturbation mechanism of these drugs. Thus, physical interaction of these drugs with membrane lipids is very crucial for their clinical use, different cellular processes, as well as for targetted drug delivery systems. In the present paper, we have reported for the first time the interaction between these drugs and the lipid molecules in the liposomal system of dipalmitoylphosphatidyl-choline (DPPC), as measured by steady-state fluorescence anisotropy using 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescent probe. Our results show that by dissolving in the lipid matrix these two drugs effectively stabilise the liposomal membrane: the effect being more in case of GT than in PT, indicating that the rigidifying effect is independent of the number of nitrate groups of the two drugs. This effect increases with the increase in drug concentration, implying solubilisation of all drug molecules. Though our in vitro study has more physical significance than a physiological one, the results obtained here may be used to interpret the effects that are observed in vivo.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Isolation, characterization, and expression of a cDNA encoding N-acetylglucosaminyltransferase V.

A cDNA clone for the complete coding sequence for alpha-1,3(6)-mannosylglycoprotein beta-1,6-N-acetylglucosaminyltransferase V (GlcNAc-T V, EC 2.4.1.155) was isolated and expressed in COS-7 cells. Degenerate oligonucleotide primers for polymerase chain reaction were synthesized based on the amino acid sequence of three tryptic peptides isolated from affinity-purified GlcNAc-T V. Polymerase chain reaction amplimers were isolated from rat and mouse mRNA. A cDNA-encoding full-length enzyme was isolated from a rat 1 cell (EJ-ras-transformed) library and sequenced. Transient expression of this clone in COS-7 cells, followed by enzymatic activity assays, demonstrated that this cDNA sequence encodes GlcNAc-T V. Northern analysis of rat kidney mRNA revealed a single band corresponding to a length of about 7 kilobases. Sequence analysis of the cDNA clone demonstrated an open reading frame that encoded a type II membrane protein of 740 amino acids.

Amino Acid Sequence↗
PubMed1993

Biophysical characterization of Vibrio El Tor typing phage e5.

Vibrio cholerae typing phage e5, which can lyse only the El Tor strains of V. cholerae, was characterized. The phage had a polyhedral head 51 nm in diameter and a short tail 13 nm in length. It contained 13 structural polypeptides, with the molecular mass of the major component being 50 kDa. Phage chromosome comprised a 38.5-kb linear double-stranded DNA molecule with unique termini, as determined by restriction fragment analysis and electron microscopy, and had a G+C content of 35.5%. A physical map was constructed with the restriction endonucleases HaeII and HpaII. Adsorption of the phage to its host followed a biphasic kinetics and its intracellular growth was characterized by a latent period of 15 min and a burst size of 100 particles per infected cell. The phage was found to be moderately thermotolerant.

Bacteriophages↗
PubMed1993

Photoinduced proton transport mechanism in merocyanine-dye-probed planar lipid membranes.

Planar lipid membranes were used to study photovoltage generation after the incorporation of various merocyanine dyes. These dyes undergo photochemical isomerization on illumination and can act as a photon-driven facilitated proton transport system under suitable conditions. This system has the advantage of preventing back recombination of the photodissociated charges, thus improving its storage capacity. A sufficiently high photovoltage, with a long storage time and good reproducibility, was obtained with these dyes. The spectral studies indicate the formation of a 1:1 complex between dye and lipid molecules. Our results show that the strength and stability of complex formation increase with the hydrophobicity of the dye which, in turn, increase the magnitude and storage of the photovoltage generated in the system.

Alkanes↗
PubMed1989

Gallstone lithotripsy with the pulsed dye laser: in vitro studies.

The use of a pulsed dye laser to fragment human gallstones is reported. Laser energy was delivered by a 320 microns quartz fibre at wavelengths of 440, 480, 504, 560, 590, and 635 nm, in 1 microsecond pulses at energies of 5-60 mJ per pulse, producing peak powers of the order of 10(5) W. Cholesterol, pigment and mixed stones were fragmented. The shorter wavelengths were most efficient, using significantly less energy at 440 and 480 nm than at the longer wavelengths. Pigment stones were fragmented with significantly less energy than those in which cholesterol predominated. Thermal imaging during laser treatment showed no significant rise in temperature in the bulk of the stone. Absorption spectroscopy of bile revealed a peak at 450 nm, coinciding with the known absorption characteristic of bilirubin. Bile strongly attenuated light at shorter wavelengths, even at dilutions as great as 1:20 and protected samples of biliary epithelium from laser damage except when the optical fibre was in direct contact. The pulsed dye laser may offer significant advantages over current methods of biliary stone fragmentation.

Bile↗
PubMed1989

Defining parameters for peripheral laser angioplasty.

In vitro studies are reported using a Pulsed Dye laser at wavelengths of 440, 480, 504, 560 and 590 nm, to vaporise multiple samples of yellow, fibrous and calcified plaque. The threshold for crater production at 440 nm was 5 mJ/pulse and at 590 nm 65 mJ/pulse. Crater depth was significantly deeper at the short wavelengths (440, 480 and 504 nm) than at the longer (560 and 590 nm). Light microscopy confirmed the absence of thermal damage associated with continuous wave lasers. Electron microscopy revealed smooth-contoured craters and no disruption of subcellular elements at the crater margin. Samples of thrombus- and atheroma-occluded human femoral artery were successfully recanalised at the 480 nm wavelength with atraumatic spherical-tipped and modified spherical tipped optical fibres. The advantages of pulsed laser energy in peripheral vessel recanalisation are discussed.

Aorta↗
PubMed1987

Inducible reactivation of UV-irradiated cholera phage e5 in Vibrio cholerae MAK757.

The survival of UV-irradiated cholera phage e5 was found to increase when the host cells, Vibrio cholerae MAK757, were exposed to a low dose of UV irradiation before phage infection (Weigle reactivation), indicating the existence of a UV-inducible DNA repair pathway (SOS repair) in V. cholerae MAK757. The induction signal generated by UV irradiation was transient in nature and lasted about 20-30 min at 37 degrees C. Maximal Weigle reactivation of the phage was obtained when the host cells were irradiated with a UV dose of 16 J/m2. V. cholerae MAK757 was also found to possess efficient photoreactivation and host cell reactivation of UV-damaged DNA in phage e5.

Bacteriophages↗
PubMed1981

Genetic toxicological of some plant flavonoids by the micronucleus test.

4 important flavonoid compounds, namely quercetin, kaempferol, neohesperidin dihydrochalcone and rutin, were administered to male mice for the detection of gross chromosomal anomalies by the micronucleus test. The first 3 compounds were positively clastogenic to different extents, whereas the 4th was negative.

Animals↗
PubMed1981

Enhancement and inhibition of phagocytic activity in the retinal pigment epithelium.

The phagocytic activity of the pigmented epithelium of the bovine retina was studied with an organ culture model. Latex particles coated with immunoglobulin, or bovine rod outer segments, both labelled with radioactive iodine, were the objects to be phagocytosed. Various agents were tested with this model for their effects on phagocytosis by the retinal pigment epithelium. Iodoacetate significantly inhibited phagocytosis, as did penicillin, though to a lesser extent. Concanavalin A and gentamicin enhanced phagocytosis. Dimethyl sulfoxide had no effect. The results with lymphokines were not conclusive.

Animals↗