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Biomedical subjects

S Chakraborty

Publications and source records attributed to S Chakraborty.

At least 109 records · Page 6Linked to original sources
PubMed1995

Plasma prolactin and luteinizing hormone during termination and onset of photorefractoriness in intact and pinealectomized European starlings (Sturnus vulgaris).

Plasma levels of prolactin and luteinizing hormone have been examined in intact and pinealectomized European starling (Sturnus vulgaris) during termination and onset of photorefractoriness. Photorefractory starlings exposed to long (18L:6D) daily photoperiods for 10 weeks were pinealectomized. One week after pinealectomy these birds, along with the intact and sham-operated birds, were transferred to short (8L:16D) daily photoperiods. After 10 weeks on short day lengths the daily photoperiod was switched to long (18L:6D) and the birds remained on this regime for a further 10 weeks. Plasma prolactin and luteinizing hormone were determined prior to pinealectomy and then weekly throughout the experiment. Molt scores were also recorded. Profiles of both the hormones and the molt pattern were similar in pinealectomized, sham-operated, and intact control starlings. In European starlings the pineal gland does not seem to exert significant effects on the photoinduced rise in plasma prolactin and luteinizing hormone seen in photosensitive birds. It is also suggested that pinealectomy has no significant effect on the dissipation and onset of photorefractoriness assessed from plasma luteinizing hormone secretion in this bird.

Animals↗
PubMed1995

2-Mercaptopropionylglycine affords enhanced radioprotection after a liposome encapsulation.

Use of radioprotective drugs in radiotherapy is desirable to protect normal tissues. 2-mercaptopropionylglycine (MPG) has shown promising results in experimental radioprotection. In this report, a liposome drug delivery system for MPG has been used in Swiss albino mice exposed to 1 to 8 Gy whole body Gamma-irradiation to test whether or not this modality enhances the MPG afforded radioprotection. A statistically significant, dose dependent enhancement of protection by liposome encapsulated MPG (LEM) was observed. LEM, as compared to free MPG, improved the viabilities of spleen and bone marrow cells by factors between 1.11 and 2.23 for different doses of radiation.

Animals↗
PubMed1995

Quantitative image analysis of MIB-1 immunoreactivity. A comparison with flow cytometric assessment of proliferative activity in invasive carcinoma of the breast.

Proliferative activity, especially flow cytometrically determined S-phase fraction, is generally accepted as an important prognostic indicator in carcinoma of the breast. We studied cellular proliferation in 53 breast carcinomas using quantitative image analysis of immunoreactivity to a recently available monoclonal antibody, MIB-1, which is applicable to formalin-fixed, paraffin-embedded tissues. MIB-1 is a murine monoclonal antibody that reacts with the Ki-67 nuclear antigen expressed by proliferating cells in the late G1, and G2/M phases of the cell cycle. These results were compared to flow cytometric determinations of S-phase and S + G2/M phase fractions obtained from corresponding fresh tissue samples. There was a good correlation between quantitative immunoreactivity to MIB-1 as measured by image analysis and flow cytometric S-phase and S + G2/M phase fractions (r = .63, P < .00001; r = .607, P < .00001, respectively). Immunoreactivity to MIB-1 and flow cytometric S-phase and S + G2/M phase fractions were significantly increased in aneuploid tumors as compared to diploid tumors. Histologic grade correlated with flow cytometric S-phase and S + G2/M phase fractions and MIB-1 immunoreactivity as determined by image analysis. There was a correlation between tumor size and MIB immunoreactivity. No proliferative parameters significantly correlated with lymph node status. Assessment of proliferative activity by quantitative image analysis of immunoreactivity to monoclonal MIB-1 antibody may be employed in cases of invasive carcinoma of the breast in which flow cytometric analysis fails to result in quantitative proliferative values, or it may be used as an alternative measurement of such proliferative activity.

Adenocarcinoma↗
PubMed1995

Postcardiac injury rheumatism.

The incidence, clinical comparison, laboratory features, therapeutic choices with outcomes of early and late postcardiac injury rheumatism (PIR) were studied prospectively. Out of the 249 patients who survived cardiac surgery, 20 (8%) and 22 (9%) patients had early and late PIR respectively. Earlier onset (within two weeks of surgery), milder articular involvement, absence of constitutional features and laboratory abnormalities and good response to analgesics were characteristics of early PIR. In contrast, late PIR which occurred between the third and fourteenth week after surgery was associated with more marked articular involvement along with systemic and laboratory abnormalities and required longer analgesic therapy, steroid support or prolonged physiotherapy in different combinations. We conclude that two distinct rheumatic syndromes with different clinical dimensions and therapeutic options can occur after cardiac surgery.

Adolescent↗
PubMed1995

Parenteral ciprofloxacin in persistent diarrhoea in children.

In a controlled trial of 30 cases of persistent diarrhoea in infants, ciprofloxacin was used parenterally for systemic antibiotic therapy. Group A cases (15 in number) were treated with parenteral ciprofloxacin and group B control cases (remaining 15) were treated with parenteral ampicillin and chloramphenicol or ampicillin/amikacin along with treatment of dehydration and malnutrition. All group A cases had excellent response and 9 infants of group B had no response up to day 4. After stopping all other drugs and with parenteral ciprofloxacin they responded favourably. Follow-up of all the cases was done regularly every 2 weeks for 6 months after discharge. No toxicity of ciprofloxacin was noted.

Anti-Bacterial Agents↗
PubMed1994

DNA ploidy measurements in prostate cancer: differences between image analysis and flow cytometry and clinical implications.

The relationship between DNA ploidy and prognostic parameters has been established in prostate cancer. However, comparison of various techniques used for DNA ploidy analysis has not been sufficiently addressed in prostate carcinoma. In the present study, grossly identified discrete carcinoma foci from 48 consecutive radical prostatectomy specimens were analyzed by flow cytometry and image analysis using both imprints and tissue sections. Correlations with other prognostically important pathological findings such as grade, size, extracapsular extension, positive surgical margin, and seminal vesicle and lymph node involvement were done. Image analysis detected 26 (54.2%) nondiploid tumors compared to 15 (31.3%) nondiploid tumors by flow cytometry. No significant differences were demonstrated between imprints and tissue sections. DNA ploidy status showed a good correlation with most other pathological findings listed above. In conclusion, DNA ploidy status determination gives clinically useful information which correlates well with the other useful pathological parameters of prognostic importance. Image analysis may be more sensitive than flow cytometry in detecting nondiploid populations. Tissue sections appear to be as reliable as imprints when properly controlled.

Adenocarcinoma↗
PubMed1994

Ascorbate protects guinea pig tissues against lipid peroxidation.

In recent years we and others have shown that ascorbic acid (AH2) is a potential scavenger of superoxide (O2.-) and peroxyl (LOO.) radicals, the species involved in lipid peroxidation (LPO) in animal tissues. In this paper we have demonstrated that AH2 protects guinea pig tissues from LPO both in vivo and in vitro. The extent of LPO has been determined by estimating malonaldehyde using the thiobarbituric acid test and HPLC and also by measuring the accumulation of fluorescent pigment and occurrence of protein changes in the microsomal membranes. In AH2-deficiency, LPO occurs progressively in guinea pig tissues, despite the presence of adequate levels of antioxidants like alpha-tocopherol, GSH, protein thiols, and scavenging enzymes, namely, superoxide dismutase, catalase, and glutathione peroxidase. In a model in vitro system, microsomal LPO initiated by O2.- is completely prevented by AH2 but not by alpha-tocopherol, GSH, uric acid, and catalase. AH2 is also the most effective antioxidant in preventing microsomal LPO mediated by tert-butylhydroperoxide or the chain propagating species LOO., generated from 2,2'-azobis (2-amidinopropane) hydrochloride. The results obtained with guinea pigs may be applicable to humans, because humans are also dependent on dietary AH2. Our data suggest that an adequate vitamin C nutrition may prevent common cellular degenerative diseases associated with LPO.

Adrenal Glands↗
PubMed1994

Clostridium difficile in antibiotic associated pediatric diarrhea.

A case control study was carried out at the medical wards of Dr. B.C. Roy Memorial Hospital for Children, Calcutta, between January and September 1989. One hundred eleven hospitalized children up to the age of 5 years, receiving antibiotics for different medical problems, developed antibiotic associated diarrhea. Isolation of Clostridium difficile as sole pathogen was very low (3.6%) from these patients. Fecal samples of 111 case matched control children were also screened for C.difficile. Only 2.7% fecal samples of control children were positive for C.difficile. All the strains of C.difficile isolated from antibiotic associated diarrhea cases showed neutralisable cytotoxin in in vitro test. In contrast none of the strains isolated from control children showed cytotoxicity. This study suggests that C.difficile is not an important pathogen related to antibiotic associated diarrhea in children at this hospital.

Anti-Bacterial Agents↗
PubMed1994

Mutations in the lysosomal beta-galactosidase gene that cause the adult form of GM1 gangliosidosis.

Three adult patients with acid beta-galactosidase deficiency/GM1 gangliosidosis who were from two unrelated families of Scandinavian descent were found to share a common point mutation in the coding region of the corresponding gene. The patients share common clinical features, including early dysarthria, mild ataxia, and bone abnormalities. When cDNA from the two patients in family 1 was PCR amplified and sequenced, most (39/41) of the clones showed a C-to-T transition (C-->T) at nucleotide 245 (counting from the initiation codon). This mutation changes the codon for Thr(ACG) to Met(ATG). Mutant and normal sequences were also found in that position in genomic DNA, indicating the presence of another mutant allele. Genomic DNA from the patient in family 2 revealed the same point mutation in one allele. It was determined that in each family only the father carried the C-->T mutation. Expression studies showed that this mutation produced 3%-4% of beta-galactosidase activity, confirming its deleterious effects. The cDNA clones from the patients in family 1 that did not contain the C-->T revealed a 20-bp insertion of intronic sequence between nucleotides 75 and 76, the location of the first intron. Further analysis showed the insertion of a T near the 5' splice donor site which led to the use of a cryptic splice site. It appears that the C-->T mutation results in enough functional enzyme to produce a mild adult form of the disease, even in the presence of a second mutation that likely produces nonfunctional enzyme.

Adult↗
PubMed1993

A comparative study of annual changes in the pineal gland morphology with reference to the influence of melatonin on testicular activity in tropical birds, Psittacula cyanocephala and Ploceus philippinus.

The aim of the present comparative investigation was to examine annual pineal cytological changes and the action of melatonin in relation to testicular activity in two wild tropical avian species. The findings revealed that in both blossomheaded parakeets (Psittacula cyanocephala) and Indian weaver birds (Ploceus philippinus) the pineal gland was inactive, with reduced karyometric values during the breeding season. A pinealoactive phase showing significantly increased pinealocyte nuclear diameter corresponded with the nonbreeding phase. Administration of melatonin (250 micrograms/100 g body wt) for 10 consecutive days caused significant involution of testes during the breeding phase, although it failed to alter reproductive activity during the nonbreeding phase. The results indicated that the pineal gland activity varied inversely with the seasonal testicular weight cycle and the antigonadal influence of melatonin appeared to be phase dependent, which corroborated the inverse temporal relationship of the pineal gland and male reproductive activity examined in the two tropical avian species.

Acclimatization↗