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Biomedical subjects

K Chaudhuri

Publications and source records attributed to K Chaudhuri.

At least 37 records · Page 2Linked to original sources
PubMed1992

Tuberculous infection in a rural population of south India: 23-year trend.

A survey was conducted in Bangalore district of south India between February 1984 and January 1986 to study the tuberculosis infection rate. The data from this survey, along with the information derived from the earlier ones in the same area conducted between 1961-1968, have been used in the report to study the trend of tuberculosis. Tuberculin test results in 0- to 14-year-old unvaccinated children from each survey were distributed, and based on the antimode, infected persons were identified. The standardized prevalence rates in population from the surveys were converted into risk rates by using the TSRU methodology and compared. The average annual risk of infection of 1.1% observed in 1961 declined to 0.61% in 1985, representing a decline of approximately 37% in nearly 23 years. This amounted to an average decline of 3.2% per annum over the period. The trend probably represented a natural dynamics. Whether organized intervention played some role could not be commented upon. Similar studies in other parts of the country are recommended in order to have information on the trend in the country as a whole.

Adolescent↗
PubMed1992

Presence of exposed phospholipids in the outer membrane of Vibrio cholerae.

Vibrio cholerae 569B was found to be highly sensitive to a wide range of chemicals, particularly hydrophobic compounds and neutral and anionic detergents. The phospholipid profile of the outer membrane was similar to that reported for other Gram-negative bacteria. The lipopolysaccharide (LPS) contained O-antigenic sugars and exhibited heterogeneity. In addition, the LPS moiety was characterized by a relatively low negative charge. Analysis by topological probes revealed the presence of a significant amount of exposed phospholipids in the outer membrane. The reduced negative charge of LPS molecules and the exposed phospholipids present in the outer membrane could be important in the increased permeation of exogenous compounds in V. cholerae.

Binding Sites↗
PubMed1992

Interaction of Vibrio cholerae cells with beta-lactam antibiotics: emergence of resistant cells at a high frequency.

Unlike other gram-negative enteric bacteria, Vibrio cholerae cells were equally susceptible to penicillin and ampicillin and in general more susceptible than Escherichia coli to most of the beta-lactam antibiotics. The turbidity of penicillin-treated cultures contained to increase exponentially for about 3 h, although the cell viability declined rapidly within 30 min of penicillin addition. Prolonged treatment with beta-lactam antibiotics produced cells resistant to these antibiotics. A fluctuation test indicated that this resistance might be due to adaptive mutation. Cells resistant to a beta-lactam exhibited broad cross-resistance to other beta-lactam antibiotics. A new 12,000-Da outer membrane protein was detected both in beta-lactam-resistant cells and in wild-type cells growing in medium containing beta-lactam antibiotics. While the penicillin-resistant cells had all of the penicillin-binding proteins (PBPs) present in the parental cells, significant differences in the relative proportion of low-molecular-weight PBPs were seen. The low-molecular-weight PBPs from resistant cells seemed to form more stable complexes with penicillin than those from the parental strain.

Anti-Bacterial Agents↗
PubMed1992

Cell surface characteristics of environmental and clinical isolates of Vibrio cholerae non-O1.

The cell surfaces of several toxigenic and nontoxigenic environmental and clinical isolates of Vibrio cholerae non-O1 have been examined. The environmental strains, irrespective of toxigenicity, are significantly more resistant to antibiotics and detergents than are V. cholerae O1 strains. The clinical isolates of non-O1 vibrios are as sensitive to a wide variety of chemicals as the O1 vibrios. The environmental non-O1 strains are also less susceptible to lysis when treated with protein denaturants or neutral and anionic detergents than are O1 vibrios and the clinical non-O1 strains. In contrast to O1 vibrios, the environmental non-O1 vibrios do not have exposed phospholipids in their outer membranes. These features of the cell surfaces of environmental non-O1 vibrios might have a role in the better survival of these organisms under environmental fluctuations.

Anti-Bacterial Agents↗
PubMed1992

Haematological manifestations of primary Sjögren's syndrome: a clinicopathological study.

Clinically significant cytopenias are thought to be uncommon in primary Sjögren's syndrome: only a few cases have been reported in the literature. Over a 3-year period we identified haematological abnormalities in 11 of 27 patients with Sjögren's syndrome. Six patients had a positive direct antiglobulin test, including one patient with all the features of autoimmune haemolytic anaemia and two others with some features of this condition. Four patients had immune thrombocytopenia and two patients had myelodysplastic syndrome. Neutropenia was noted in two patients, one patient had aplastic anaemia and one had pure red cell aplasia. Haematological disorders were found to be common in patients with Sjögren's syndrome (40 per cent). Accordingly, we suggest that patients with immune cytopenia(s) should be screened for Sjögren's syndrome using sensitive assays for anti-SS.A and anti-SS.B antibodies, and that patients with Sjögren's syndrome should be periodically monitored, with a full blood count to rule out any haematological abnormality.

Adolescent↗
PubMed1991

HIV antibody screening of commercially available blood products in India.

In a screening of 182 vials of various commercially available blood products in the Indian market, 32 (17%) were found to contain HIV-1 antibodies. The contamination with HIV-1 antibodies was detected in all types of blood products including immunoglobulin preparations, cryoprecipitates as well as albumin. Interestingly, the contamination was seen almost exclusively in the products manufactured in the Bombay-Pune area (32 of 92, 34%). It was very low in products manufactured near Delhi (1 of 90). A single vial of imported Factor VIII concentrate tested negative.

Biological Products↗
PubMed1990

Prenatal diagnosis of autosomal dominant microcephaly and postnatal evaluation with magnetic resonance imaging.

A case of fetal autosomal dominant microcephaly was prenatally diagnosed with ultrasonography in a woman with previously undiagnosed microcephaly. At the time of initial ultrasonographic assessment, the mother was identified to have a markedly small cranium, consistent with maternal microcephaly. The ultrasonographic examination showed the fetal head size to be four standard deviations below the mean for gestational age. Gestational dating from the other biometric parameters and from the last menstrual period was consistent with 31 weeks' gestation. Neurosonographic evaluation of the fetus revealed no obvious structural abnormalities. Serial ultrasonographic examinations at 35 and 38 weeks' gestation showed no changes in the fetal head size. A 2.64 kg male fetus was delivered at term. Neonatal assessment showed the fetal head circumference to be less than the second percentile for gestational age. Neurologic assessment of the neonate with magnetic resonance imaging showed abnormal development of the brain, with small cerebellar and cerebral hemispheres, and pachygyria. These images are compared with the magnetic resonance images of the mother. Our findings of maternal and fetal microcephaly are consistent with autosomal dominant microcephaly. To our knowledge, this is the first report of the prenatal diagnosis of autosomal dominant microcephaly.

Adult↗
PubMed1990

Bioeconomic dynamics of a fishery modeled as an S-system.

A bioeconomic model of a single species fishery is developed by using a realistic catch-rate function and assuming that a regulatory agency controls exploitation of the fishery by imposing a suitable tax on the catch. The existence of a nontrivial steady state and its stability are examined. The optimal harvesting policy is discussed from the viewpoints of variational calculus and control theory. The fishery is then modeled as an S-system by following the recasting techniques of Savageau and Voit. Numerical examples of the optimal control curves and the yield-effort curves are obtained by executing the ESSYNS algorithm.

Fisheries↗
PubMed1990

Human immunodeficiency virus infection in the blood donors of Delhi, India.

In the present study, blood from paid and unpaid donors was screened for the presence of HIV infection using a competitive ELISA test. None of the 8,000 unpaid donors but 4 (0.23%) of the 1,700 paid donors showed evidence of HIV infection. All of these four ELISA-positive samples were confirmed by the Western blot test. The present study indicates that HIV infection has entered the group of paid donors in the Delhi metropolitan area. Careful donor screening, discouraging use of paid donors, and stringent screening of donated units of blood has become mandatory in India to prevent HIV transmission through blood and blood products.

Adult↗
PubMed1990

HIV serosurveillance among prostitutes and patients from a sexually transmitted diseases clinic in Delhi, India.

Screening of 701 prostitutes in Delhi for HIV antibodies by a competitive ELISA test and supplementary Western blot test showed that only one of them was infected. Of the 4,572 samples from the patients attending a sexually transmitted disease clinic in Delhi, none showed evidence of HIV infection. In contrast to this low frequency of HIV infection in Delhi, a much higher frequency has been reported to the Indian Council of Medical Research from major metropolitan centers on the coast of India, namely, Bombay and Madras and their surrounding areas. It is possible that the infection is making inroads from these coastal areas to the interior of the country.

Adolescent↗
PubMed1987

Morphological study of the combined effect of purpurin derivatives and light on transplantable rat bladder tumors.

Purpurin derivatives, a group of synthetic photosensitizers, were tested for their photodynamic activity against transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide-induced urothelial tumors growing in male Fischer 344 rats. Histological examination of tumors in animals treated with the purpurin derivatives and red light (greater than 590 nm, 360 joules/cm2) revealed tumor cell necrosis 24 h after completion of therapy. Control tumors showed no histological change. Purpurins have a major absorption peak in the red region (greater than 650 nm) of the visible spectrum, a region with good tissue penetration, and purpurins can be synthesized with a high degree of purity. This study demonstrates the potential of purpurin derivatives as photosensitizers for photodynamic cancer therapy.

Animals↗
PubMed1986

Photodynamic treatment of transplantable bladder tumors in rodents after pretreatment with chloroaluminum tetrasulfophthalocyanine.

Chloroaluminum tetrasulfophthalocyanine (AlPCS) was used as a photosensitizer for the photodynamic treatment of transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) induced urothelial tumors. Two groups of six rats each were injected with AlPCS (three micrograms./gm. body weight) and 24 hours after injection underwent photodynamic treatment with red light (greater than 590 nm., 360 joules/cm.2). Tumors examined four hours (Group I) and 24 hours (Group II) after the completion of phototreatment showed extensive hemorrhagic necrosis. Tumors treated with AlPCS alone showed no changes. In two other groups of six rats each, blood flow to tumors treated with AlPCS alone (Group III) and AlPCS plus light (Group IV) was measured using the radioactive microsphere technique. AlPCS plus light resulted in a significant decrease (p less than .05) in tumor blood flow within 10 minutes of completion of phototreatment while AlPCS alone had no effect on tumor blood flow. These findings are similar to those observed when higher doses (10 micrograms./gm. to 20 micrograms./gm. body weight) of hematophorphyrin derivative (HpD) and light were used for phototreatment of FANFT induced tumors. AlPCS is a stable sulfonated derivative of tetraazotetrabenzoporphyrin which absorbs maximally in the red portion of the visible spectrum, a region with good tissue penetration properties. These studies suggest the AlPCS may be a useful new agent for photodynamic therapy of cancer.

Animals↗
PubMed1986

Histological study of the effect of hematoporphyrin derivative photodynamic therapy on the rat jejunum.

Hematoporphyrin derivative photodynamic therapy is evolving as a local treatment for neoplastic disease. The emphasis of previous research has been on the determination of mechanisms of tumoricidal activity and defining the tumoricidal porphyrin component in hematoporphyrin derivative. The effect of hematoporphyrin derivative photodynamic therapy on normal tissue has received little attention. In the following study we examined the morphological changes of normal rat intestine exposed to hematoporphyrin derivative and light. In this model a segment of rat jejunum was exposed to red light (greater than 590 nm; 360 J/cm2) 24 or 72 h after the i.v. administration of hematoporphyrin derivative (5 or 10 micrograms/g body weight). Control groups received either no treatment, hematoporphyrin derivative only, or light only. Four h after treatment, intestinal segments were removed and examined by light microscopy. Segments treated with hematoporphyrin derivative and light showed extensive sloughing of the mucosa and submucosa with sparing of the muscular and serosal layers. It appears that hematoporphyrin derivative photodynamic therapy is capable of causing mucosal and submucosal damage to normal rat jejunum at these doses of light and hematoporphyrin derivative.

Animals↗