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Biomedical subjects

A Chakrabarty

Publications and source records attributed to A Chakrabarty.

17 recordsLinked to original sources
PubMed1998

Immunohistochemical analysis of cyclin A in astrocytic tumours.

Cyclins are important regulators of the cell cycle; there is increasing evidence that some cyclins are positively involved in carcinogenesis. Amplification and translocation of the cyclin genes and overexpression of their mRNAs and proteins have been observed in a variety of tumours. We studied cyclin A protein in astrocytic tumours by immunohistochemical analysis. Immunohistochemistry with microwave antigen retrieval was carried out on formalin fixed, paraffin embedded material from 15 glioblastomas (WHO grade IV), 10 anaplastic astrocytomas (WHO grade III), seven diffuse low grade astrocytomas (WHO grade II) and nine pilocytic astrocytomas (WHO grade I) using antibodies against cyclin A and a proliferation marker MIB1. Staining for these antibodies was seen mainly in the tumour cell nuclei; 66% of all cases showing staining for cyclin A and 95% of all cases staining for MIB1. Mean labelling indices (LI) for cyclin a were higher in glioblastoma (mean LI-6.7) and anaplastic astrocytoma (mean LI-5.9) than low grade diffuse astrocytoma (mean LI-1.7) and pilocytic astrocytoma (mean LI-0.12), although there was no clear cut off point between the various tumour types. A good correlation was seen between labelling indices of cyclin A and MIB1 (Pearson correlation coefficient r = 0.59, P < 0.0001). Cyclin A is variably expressed in astrocytic tumours, either reflecting increased tumour proliferation (cyclin A being an integral component of the cell cycle), an alteration of its gene, protein upregulation or regulation of apoptosis. The genetic basis of expression of cyclin A in astrocytic tumours remains to be determined.

Antigens, Nuclear↗
PubMed1996

Cyclin D1 in astrocytic tumours: an immunohistochemical study.

Forty-eight astrocytic tumours were stained immunohistochemically with antibodies to the cell cycle-regulating protein, cyclin D1, and to the proliferation marker MIB1 (Ki-67) using formalin fixed paraffin embedded tissue and a microwave antigen retrieval system. Cases were classified by the WHO system (1993). The labelling indices (LI) for both antibodies were compared with each other and with the tumour type. The mean labelling indices for both antibodies increased with the degree of malignancy, and a significant difference was seen between the pilocytic astrocytoma and diffuse astrocytoma together vs anaplastic astrocytoma and glioblastoma together. However, within each tumour type there was considerable variation in the labelling indices and a clear cut off value could not be demonstrated. There was a strong positive correlation between labelling indices for cyclin D1 and MIB1 in diffuse astrocytoma, but this correlation broke down increasingly in anaplastic astrocytoma and glioblastoma. There was poor correlation between cyclin D1 and MIB1 in pilocytic astrocytoma, a feature which appeared to separate them from the diffuse astrocytoma. Average labelling indices for cyclin D1 were higher than those of MIB1, which suggests that cyclin D1 positive cells represent a pool of cells from which proliferation and hence MIB1 expression can take place. In conclusion, cyclin D1 is overexpressed in astrocytic tumours, more so with increasing grade of malignancy and in a way which approximately correlates with MIB1 expression.

Antigens, Neoplasm↗
PubMed1996

Priapism associated with sickle cell hemoglobinopathy in children: long-term effects on potency.

PURPOSE: Children with sickle cell priapism have traditionally been treated conservatively with surgery done as a last resort. Only sparse subjective data are available on the long-term assessment of potency in these patients. MATERIALS AND METHODS: We retrospectively reviewed the charts of all pediatric patients with sickle cell priapism who presented to Children's Hospital of Michigan between 1972 and 1992, and subsequently assessed erectile capabilities subjectively by questionnaire and objectively by RigiScan. RESULTS: Of the 15 patients interviewed 5 had undergone shunt procedures. The return of potency tended to vary inversely with patient age at onset and duration of priapism. CONCLUSIONS: Shunts performed within 48 hours, especially in postpubertal children, seemed more likely to preserve potency.

Adolescent↗
PubMed1996

Electron microscopic characteristics of actinomycetic agents having aetiological association with human leprosy and epizootic ulcerative syndrome of fish.

The transmission electron microscopic (TEM) studies of the human leprosy derived chemoautotrophic nocardio-form (CAN) bacteria and EUS derived CAN bacteria showed presence of double contoured cell-walls consisting of an electron transparent and a dense layer. The fibrillar structures on the surface of these CAN bacterial cells also suggested their similarity to the human tissue derived Mycobacterium leprae cells. These EM studies further revealed mycelial and coccoid bodies in all these bacteria as was observed originally.

Actinomycetales↗
PubMed1995

Renin-producing leiomyosarcoma originating in the uterus.

We present a case of uterine leiomyosarcoma in a 60-year-old woman, who had severe hypertension with hypokalaemia and metabolic alkalosis. Investigation revealed an elevated serum renin level; the tumour stained for renin on immunocytochemistry. The serum renin level fell on successful treatment of the primary. We suggest that this is the first reported case of uterine leiomyosarcoma shown to be producing renin.

Female↗
PubMed1995

Acquired rectourethral fistula: methods of repair.

Rectourethral fistulas are a rare but devastating complication of urinary or rectal surgery, trauma or inflammation. Historically repair has posed a challenge because of technical difficulties and the high incidence of recurrent fistulas. We report 7 cases of acquired rectourethral fistulas of varying etiology (3 after prostatectomy, 3 after trauma and 1 after recurrent perineal abscess), which were managed by various means. Our data and those in the literature suggest that the first attempt at repair is the best and subsequent repairs become increasingly difficult; the York Mason approach allows easy accessibility with minimal risk of complications and the best chance for a functionally successful outcome when a vascularized flap is not required, and some cases may have such a low probability of successful resolution of the fistula as well as maintenance of urinary continence that cystectomy and supravesical diversion are appropriate considerations.

Adolescent↗
PubMed1988

Primary choice of intervention for distal ureteric stone: ureteroscopy or ESWL?

Either transurethral ureteroscopy (URS) or extracorporeal shock wave lithotripsy (ESWL) was the primary method of intervention in two series of patients presenting consecutively with stones located in the ureter distal to the radiological marking of the sacroiliac joint. Of 65 patients treated by URS, successful evacuation of the major part of the stone was achieved in 97% in one or two sessions. Of those subsequently attending for review, 93% proved stone-free but 3% required surgery for serious complications. In the ESWL series of 53 patients, successful stone fragmentation was recorded in 94%, with 2 patients requiring a supplementary endourological or surgical procedure. No significant complications were related to ESWL and 90% of those followed up after successful ESWL proved stone-free at 6 weeks. In uncomplicated cases, the mean procedure time for ESWL was one-third of that required for URS and the hospital stay one-half. It is suggested that ESWL should be the primary method of intervention in patients with distal ureteric stone, with URS reserved for the small number that prove refractory to such treatment.

Endoscopy↗
PubMed1976

Isolation of plasmid deoxyribonucleic acid from Pseudomonas putida.

Conditions suitable for reproducible recovery of covalently closed circular deoxyribonucleic acid from strains of Pseudomonas putida containing degradative plasmids (CAM, SAL, OCT, etc.) have been defined. These degradative plasmids could not be isolated by the usual procedure, whereas RP1, an R factor of the P group, present in the isogenic strain of P. putida, was isolated equally well by either the usual procedure or the modified procedure. Characterization by electron microscopy of RP1 deoxyribonucleic acid confirmed the molecular weight (about 40 X 10(6)) previously determined by sucrose gradient centrifugation.

Biodegradation, Environmental↗
PubMedDate not supplied

Influence of tumor site on the therapy of murine kidney cancer.

OBJECTIVE: The purpose of this study was to evaluate the influence of tumor site on the therapy of an experimental murine kidney cancer model, Renca. METHODS: Equal number of tumor cells were injected subcutaneously, intraperitoneally, sub-renal capsule, and intravenously to induce tumors. The animals were then assessed for growth of the primary tumor, metastases and survival. Immunohistochemistry and flow cytometry was performed to identify the phenotype of infiltrating lymphocytes. Tumor bearing animals were treated with high dose interleukin-2 or whole body radiation, and response of the primary tumors as well as the metastases was assessed. RESULTS: Renca tumors grew well regardless of the methods of induction. Spontaneous metastasis could be best induced in the sub-renal capsule model. More consistent numbers of pulmonary metastases were obtained by intravenous injection of the tumor cells. Immunotherapy was able to reduce the size of the primary tumor as well as the number of metastasis. Whole body radiation caused some reduction in the primary tumor but did not have a major effect in reducing metastasis. CONCLUSIONS: The Renca model is a suitable animal model to study the response to different therapeutic interventions. The site of the tumor growth is not a significant variable in the response to treatment.

Adenocarcinoma↗
PubMedDate not supplied

Radiation therapy enhances the therapeutic effect of immunotherapy on pulmonary metastases in a murine renal adenocarcinoma model.

In order to improve the efficacy of immunotherapy, we have evaluated the effects of radiation therapy combined with interleukin 2 (IL-2) treatment in a murine metastatic renal adenocarcinoma model (Renca). Pulmonary metastases were induced in Balb/c mice by intravenous injection of Renca and five days later a sublethal dose of radiation (300 rads) was administered either to the whole body or to the left lung only. One day following radiation, immunotherapy was given for 5 consecutive days of IL-2 at 5,000 Cetus units intraperitoneally, twice daily. The animals were either sacrificed on day 23 or 33 to assess tumor burden, or were followed for long term survival. We found that pretreatment with irradiation greatly enhanced the therapeutic efficacy of immunotherapy and was manifested by a significant reduction in pulmonary metastases and an increase in survival. When combined with immunotherapy, local tumor irradiation was not only as effective as whole body irradiation, but irradiation of one lung reduced the number of metastases similarly in both lungs. This suggests that local tumor irradiation may act through a systemic mechanism to increase the anti-tumor response mediated by IL-2 therapy.

Animals↗