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J Basu

Publications and source records attributed to J Basu.

At least 37 records · Page 2Linked to original sources
PubMed1990

Abnormalities of the erythrocyte membrane in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a hematologic malignancy characterized by excessive growth of myeloid cells and their progenitors. The proportion of spectrin dimers compared to tetramers extracted from membranes at 4 degrees C, under low ionic strength conditions, increased in CML erythrocytes. These also displayed abnormal thermal sensitivity (between 45 and 46 instead of 49 degrees C). Crosslinking with the bifunctional reagent, dimethyl adipimidate (8.6 A) showed significant organizational modification of not only spectrin, but other cytoskeletal components such as ankyrin, bands 4.2 and 5. Enhanced concanavalin A (Con-A) agglutinability of CML erythrocytes also suggests altered topographic distribution of a functionally important membrane protein, band 3. The anion transport activities of erythrocytes from patients with CML and normal donors were comparable. In CML erythrocytes, significant reduction in the number of ankyrin-binding sites, present in the cytoplasmic domain of band 3, may lead to partial loss of cytoskeletal anchorage to the bilayer and account for their increased Con-A agglutinability and heat sensitivity and may lead to their premature removal from the circulation.

Agglutination↗
PubMed1990

Chronic myelogenous leukemia: alterations in red cell membrane band 3 and increased IgG binding.

Chronic myelogenous leukemia (CML) is a hematologic malignancy arising from an abnormal hemopoietic stem cell. Our earlier studies have identified defects in spectrin tetramer formation and organization of cytoskeletal proteins (Basu et al., Biochim. Biophys. Acta 1988, 121-126); and decreased ankyrin binding to ankyrin-depleted vesicles in CML patients. These may lead to clustering of band 3 and increased binding of autologous IgG. This has now been explored by studying the binding of 125I-protein A to normal and CML erythrocytes. There is increased binding of 125I-protein A in CML erythrocytes compared to normal erythrocytes. Since binding of autologous IgG is responsible for removal of erythrocytes from the circulation, the above findings suggest that CML erythrocytes are likely to be prematurely removed from the circulation, accounting for anemia.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1990

Depression.

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Depression↗
PubMed1990

An insight into the structure of DNA through melting studies.

Helix-coil transition of calf thymus (CT) DNA in 0.1 M NaCl was observed under different environmental conditions for studying structural and conformational changes, if any. Pre-exposure of the DNA to different types of radiations - UV and gamma-brought different degrees of change (lowering) in the melting temperature (Tm). Interaction of drugs (daunomycin and actinomycin-D) increased the Tm inducing structural stability. There was 50% more destabilisation in case of polynucleotide-drug complex as compared to DNA-drug complex exposed to UV radiation. Thermodynamic studies on DNA in D2O (0.1 M NaCl prepared in D2O) were carried out and compared with the corresponding results in H2O. Presence of D2O increased the stability of the DNA structure. Structural and conformational aspects have been discussed in the light of the results obtained.

Animals↗
PubMed1989

Purification and characterization of an extracellular lectin from Mycobacterium smegmatis.

Mycobacteria exist naturally in aggregated form and pathogenic strains colonize macrophages. A lectin has been isolated from the culture broth of M. smegmatis, which may, possibly, have an important role in either or both of these phenomena. The lectin of Mr 12,000-14,000 agglutinates erythrocytes from different species, and agglutination is reversed by arabinogalactan isolated from mycobacteria, as well as by yeast mannan. It has a pI of 5.5 and is rich in aspartic and glutamic acid residues.

Amino Acids↗
PubMed1989

Abnormalities in erythrocyte membrane band 3 in chronic myelogenous leukemia.

The anion transport activities of erythrocytes from patients with chronic myelogenous leukemia (CML) and normal donors were comparable. In CML erythrocytes, significant reduction in the number of ankyrin-binding sites, present in the cytoplasmic domain of band 3, may lead to partial loss of cytoskeletal anchorage to the bilayer and account for their increased Con-A agglutinability and heat-sensitivity (Basu, J., Kundu, M., Rakshit, M.M. and Chakrabarti, P. (1988) Biochim. Biophys. Acta 945, 121-126).

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1989

Abnormalities in the erythrocyte membrane in acute lymphoid leukaemia.

Erythrocytes from patients suffering from acute lymphoid leukaemia (ALL) show decreased proportions of spectrin tetrameters and altered spatial distribution of band 4.1 and ankyrins. These abnormalities of the cytoskeleton are probably responsible for altered membrane fluidity and transbilayer distribution of phosphatidylethanolamine in ALL. ALL is associated with severe anaemia and usually, but not always, with overproduction of lymphocytes. To our knowledge, this is the first report of abnormalities in the erythrocyte membrane in ALL which may, in part, be responsible for the observed anaemia.

Dimethyl Adipimidate↗
PubMed1989

Effects of smoking and oral contraception on plasma beta-carotene levels in healthy women.

Oral contraceptive use and smoking have been known to affect plasma vitamin levels. Total carotenoids have been studied with spectrophotometry, a relatively insensitive technique. In this study plasma concentrations of beta-carotene and retinol were measured in coded samples by sensitive high-pressure liquid chromatography in a cross-sectional study of 149 normal healthy women attending a family planning clinic. At the time of recruitment in the morning, a general health questionnaire was administered for patient age, methods of contraception, smoking habits, and food intake at breakfast. Of the 149 enrolled volunteers, 88 were oral contraceptive users and 61 were not users. Among users, 21 smoked cigarettes, and there were 18 smokers among nonusers. Oral contraceptive users had significantly lower plasma concentrations of beta-carotene (p less than 0.001) and higher retinol levels (p less than 0.0001). Plasma beta-carotene or retinol levels did not differ among users of intrauterine contraceptive devices or barrier methods of contraception. No association was noted between the plasma levels of these two micronutrients and age greater than or less than 30 years. Cigarette smoking alone was associated with significantly reduced plasma beta-carotene levels in nonusers (p less than 0.001). Combined cigarette smoking and oral contraceptive usage were associated with low plasma beta-carotene levels; the results appear to be additive. These findings suggest a possible synergistic effect on plasma beta-carotene levels from the use of both cigarette smoking and oral contraception.

Adolescent↗
PubMed1989

Plasma reduced and total ascorbic acid in healthy women: effects of smoking and oral contraception.

This is the first report of both reduced (RAA) and total (TAA) plasma ascorbic acid levels in women who smoke and are on oral contraception. 155 normal healthy subjects were investigated. A study questionnaire was completed including age, method of contraception, smoking status, and food intake at breakfast, prior to attending the clinic. Biochemical assays were promptly carried out without knowledge of subject's clinical or dietary status. One-way analysis of variance revealed that oral contraception per se, barrier or IUD methods have no effect on plasma ascorbic acid levels. The mean values (mg/dl +/- SD) for plasma RAA between smokers and nonsmokers were 0.512 +/- 0.241 and 0.601 +/- 0.263; and that for TAA were 0.565 +/- 0.232 and 0.682 +/- 0.231, respectively. Significant decreases in both plasma RAA (p less than 0.05) and TAA levels (p less than 0.001) were observed in smokers. Age was an interacting variable. No association of smoking or oral contraceptive use was seen with RAA or TAA levels among women less than 26 years, but decreases in both RAA and TAA levels were evident among smokers aged 26 years or older. The present study emphasizes the total exposure to smoking, e.g., pack years, is a significant confounding variable in the study of plasma ascorbic acid levels.

Adolescent↗
PubMed1989

Plasma retinol-binding protein in human uterine cervical dysplasias and cancer.

Plasma concentrations of retinol-binding protein (RBP) were measured in a cross-sectional study of asymptomatic normal menstruating women (n = 94) who obtained Pap smears and participated in a double-blinded nutritional survey. Controls (n = 45) were women with negative cervical cytology, normal colposcopy and no known gynecologic pathology or dysfunction. Cases (n = 49) were subjects with abnormal cytology and colposcopically directed biopsy that established cervical epithelial dysplasias histopathologically in the previous 12-month period. In addition, 8 women with cancer of the cervix were also investigated. The mean plasma concentration of RBP was significantly lower in cases than in controls (p less than 0.001). In normal females, the follicular phase of the menstrual cycle was increased. This increase was absent in the plasma of patients with cervical dysplasias (p less than 0.05). The data direct attention to a possible etiologic association between RBP in human cervical epithelial abnormalities and cancer.

Adult↗
PubMed1989

Psychic seizure.

Epilepsy is a fairly common disease. Various types of epilepsy, e.g., grand mal, petit mal, Jacksonian, akinetic, and myoclonic are usually encountered. An atypical type, presenting only with psychiatric symptoms is rarely found. A report of one such case is presented.

Adolescent↗
PubMed1988

Abnormal erythrocyte membrane cytoskeleton structure in chronic myelogenous leukaemia.

Chronic myelogenous leukaemia (CML) is a haematologic malignancy characterised by excessive growth of myeloid cells and their progenitors. Our studies show that there are several abnormalities in CML red blood cells. The proportion of spectrin dimers compared to tetramers extracted from membranes at 4 degrees C, under low ionic strength conditions, increased in CML erythrocytes. These also displayed abnormal thermal sensitivity (between 45 and 46 instead of 49 degrees C). Decreased spectrin tetramer formation observed in several hereditary anaemias has been associated with decreased red cell deformability leading to splenic sequestration. This could also be one of the causes of the severe anaemia observed in CML. Crosslinking with the bifunctional reagent, dimethyl adipimidate (8.6 A) showed significant organizational modification of not only spectrin, but other cytoskeletal components such as ankyrin, bands 4.2 and 5. Enhanced concanavalin A agglutinability of CML erythrocytes also suggests altered topographic distribution of a functionally important membrane protein, band 3.

Concanavalin A↗
PubMed1988

Purification and characterisation of a non-specific lipid transfer protein from goat liver.

A non-specific lipid transfer protein has been purified from the pH 5.1 supernatant of goat liver by DEAE-cellulose, CM-cellulose and Sephadex G-75 column chromatography. The protein shows a single band on polyacrylamide gel electrophoresis and transfers 450 nmol of phosphatidylcholine per min per mg of protein under the present assay condition. This protein has a subunit molecular weight of 12,000 and an isoelectric point of 8.65. Amino acid analysis reveals the absence of methionine. Histidine has been identified as the only N-terminal amino acid. Besides phosphatidylcholine, the protein transfers phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine and cholesterol. Chemical modification studies showed the involvement of free amino and thiol groups in the maintenance of the transfer activity of the goat liver protein.

Amino Acids↗
PubMed1988

Vaginal hydrolysis of retinyl acetate: increase in plasma retinol and retinol binding protein in women with cervical dysplasias.

We previously reported the clinical feasibility of a Phase I trial involving the topical administration of a RA gel applied cervicovaginally in women with mild or moderate cervical dysplasia. Now, we report hydrolysis and systemic absorption of the RA gel from the vagina. HPLC analysis of samples of residual gel obtained from the cervical canal after topical bolus application indicate that the RA undergoes prompt in vivo hydrolysis yielding retinol as a major metabolite. Venous blood samples of 41 subjects, who self-administered a RA gel, were analyzed for plasma retinol and RBP concentrations prior to and upon completion of a 7-day treatment course and upon return for follow-up examinations. An increase in both the concentrations of plasma retinol and RBP were detected after topical application of the RA gel. These elevated values receded after the gel administration was discontinued. No significant changes were observed in plasma retinol or RBP concentrations in placebo-treated subjects. The efficacy of RA as a chemopreventive agent in treating cervical dysplasias remains to be determined.

Diterpenes↗
PubMed1987

Chemical modification studies on a lectin from Saccharomyces cerevisiae (baker's yeast).

The effect of chemical modification on a galactose-specific lectin isolated from a fatty acid auxotroph of Saccharomyces cerevisiae was investigated in order to identify the type of amino acids involved in its agglutinating activity. Modification of 50 free amino groups with succinic anhydride or citraconic anhydride led to an almost complete loss of activity. This could not be protected by the inhibitory sugar methyl alpha-D-galactopyranoside. Treatment with N-bromosuccinimide and N-acetylimidazole, for the modification of tryptophan and tyrosine residues, did not affect lectin activity. Modification of carboxy groups with glycine ethyl ester greatly affected lectin activity, although sugars afford partial protection. Modification of four thiol groups with N-ethylmaleimide was accompanied by a loss of 85% of the agglutinating activity, and two thiol groups were found to be present at the sugar-binding site of the lectin. Modification of 18 arginine residues with cyclohexane-1,2-dione and 26 histidine residues with ethoxyformic anhydride led to a loss of lectin activity. However, in these cases, modification was not protected by the abovementioned inhibitory sugar, suggesting the absence of these groups at the sugar-binding site. In all the cases, immunodiffusion studies with modified lectin showed no gross structural changes which could disrupt antigenic sites of the lectin.

Amino Acids↗
PubMed1987

Lipid composition and amino acid transport in a nystatin-resistant mutant of Aspergillus niger.

A nystatin-resistant mutant of Aspergillus niger has been isolated and used as a model system to study the effect of altered sterol levels on lipid composition, transport behavior and physical properties of membrane lipids. There is a decrease in the sterol to phospholipid ratio in the mutant compared to the wild type. Although there is no qualitative change in phospholipid composition, the mutant contains a higher amount of phosphatidylcholine and a lower amount of phosphatidylethanolamine compared to the wild type. The most significant change is the elevated level of linoleic acid in the mutant, concomitant with a decreased level of oleic acid. These adaptive changes to nystatin resistance are manifested in the altered thermotropic behavior of membrane lipids as studied by the steady-state fluorescence polarization technique. These changes are also associated with altered membrane permeability as evidenced by the change in Vmax values for uptake of some amino acids in the mutant compared to the wild type.

Amino Acids↗
PubMed1987

Isolation and characterization of an extracellular lipase from the conidia of Neurospora crassa.

A triacylglycerol lipase (EC 3.1.1.3) from the conidia of Neurospora crassa was purified and characterized. The enzyme was purified by Sephadex G-100 column chromatography. Homogeneity was checked by PAGE, and isoelectric focusing gave a single band corresponding to a pI of 6.4. The enzyme had an apparent Mr 54000 +/- 1000 as determined by gel filtration. SDS-PAGE gave a single band of Mr 27000, suggesting the presence of two identical subunits. This lipase preferred triglycerides with C16- and C18-fatty acyl chains. It cleaved only the primary groups of triglycerides. The lipase also exhibited a marked preference for substrates containing endogenously occurring fatty acids and so may prove useful in detailed studies on the physiological relevance of fatty acyl specificity of lipases. The enzyme was not affected by detergents, or thiol-binding agents. Modification of free amino groups caused 90% inhibition, suggesting a role of these groups in the maintenance of lipase activity.

Chromatography, Gel↗