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Biomedical subjects

T S Ravikumar

Publications and source records attributed to T S Ravikumar.

62 records · Page 4Linked to original sources
PubMed1984

Effects of specific active immunization on tumor recurrence following primary tumor resection in WF rats with 1,2-dimethylhydrazine-induced bowel cancer.

Primary gastrointestinal tumors were induced in male WF rats by 16 weekly sc injections of 1,2-dimethylhydrazine [(DMH) CAS: 540-73-8; 20 mg/kg/wk]. Twenty-four to 28 weeks after the start of DMH injections, all rats were surgically explored and gastrointestinal tumors were resected. Rats with no remaining microscopic disease after operation were immunized with one of four tumor isografts. The first isograft, DMH-W163, is a poorly differentiated mucinous adenocarcinoma explanted from a colon cancer in a DMH-treated animal. It has been shown to possess antigens that cross-react with other DMH-induced bowel adenocarcinoma isografts. The second isograft, DMH-W49, is a carcinosarcoma explanted from a DMH-treated primary colon cancer. It has intermediate antigenic cross-reactivity with other colon adenocarcinoma isografts in the WF model. The third isograft, DMH-W15, is a sarcoma explanted from a DMH-induced colon cancer that does not possess antigens cross-reactive with other DMH-induced colon adenocarcinomas. The fourth isograft, SPK, is a spontaneous (non-DMH-induced) renal cell carcinoma that is immunogenic but should not contain tissue-type-specific antigens cross-reacting with the bowel cancers. Immunized rats received three sc weekly injections of 1 X 10(3) irradiated cells. Concomitant control rats received no immunization after resection of the primary tumor. Within 24 weeks of primary tumor resection, 12 of 16 (75%) rats not immunized had tumor recurrence. Only 8 of 24 (34%) rats immunized with DMH-W163 had tumor recurrence (P less than .025 compared to controls). Fifty percent of animals (10/20) immunized with the carcinosarcoma DMH-W49 had a recurrence. Animals immunized with the non-cross-reacting DMH-W15 sarcoma isograft had a recurrence rate similar to that of controls (16/20, 75%). The rats immunized with SPK were not protected from recurrence. Twelve of 19 (63%) had a recurrence at or near the suture line within 24 weeks following primary tumor resection. These results confirm that adjuvant immunotherapy can decrease the rate of recurrence following primary tumor resection in this model. In addition, immunogens that possessed tissue-type-specific antigens were more effective in preventing tumor recurrence than those that did not.

1,2-Dimethylhydrazine↗
PubMed1983

The association of Fanconi's anemia and squamous cell carcinoma.

Fanconi's anemia is a rare autosomal recessive disorder which manifests itself in early childhood, presenting as pancytopenia, pigmentation changes, skeletal deformities, small statures and chromosomal aberrations. Most patients ultimately die from sepsis as a result of their hematologic abnormalities, however, some patients live long enough to develop malignancies such as leukemia, hepatocellular carcinomas and squamous cell carcinoma. The association of Fanconi's anemia and squamous cell carcinoma is examined with a report of a patient with Fanconi's anemia and squamous cell carcinoma of the pyriform sinus and hypopharynx.

Adult↗
PubMed1983

Surgical resection for isolated cardiac metastases.

We performed what we believe to be the second successful resection of metastatic liposarcoma to the heart using cardiopulmonary bypass. Analysis of ten previous resections of cardiac metastases from a variety of tumors from distant primary sites revealed survivals from four months to two years. When patients can tolerate a major operative procedure, resection of solitary cardiac metastases can be successful if the primary tumor is well controlled. Patients with sarcomas and with long disease-free intervals should strongly be considered for aggressive surgical therapy. Computed tomographic scans of the chest were useful in the diagnosis and accurate delineation of the extent of tumor.

Aged↗
PubMed1983

The syndrome of inappropriate ADH secretion secondary to vinblastine-bleomycin therapy.

A clinical picture compatible with the syndrome of inappropriate ADH (antidiuretic hormone) secretion was observed in two patients receiving vinblastine-bleomycin chemotherapy. The mechanism by which this response is brought about is unclear. Penetration of Vinka alkaloids into CSF of humans is poor in the absence of extensive meningeal involvement, and hence an indirect method of action by a reduction in the osmotic threshold for vasopressin release has been suggested. By administering vinblastine on days 1 and 4 (instead of days 1 and 2, as suggested in the high-response regimen consisting of vinblastine, bleomycin, and cis-platinum) we have found better bone marrow tolerance and have not noticed the inappropriate ADH syndrome.

Adult↗
PubMed1977

Diagnostic Peritoneal Tap.

Diagnostic peritoneal tap has been an invaluable tool in the early diagnosis of acute abdominal catastrophy. We have discussed the role of abdominal paracentesis in 27 cases of blunt abdominal trauma and acute abdomen, where the diagnosis was in doubt despite clinical and emergency investigations. A simple method of tapping was adopted and there have been no complicatons.

Abdomen, Acute↗
PubMedDate not supplied

Subcutaneous lateral internal sphincterotomy for chronic fissure-in-ano.

The results of subcutaneous lateral internal sphincterotomy for chronic fissure-in-ano were analyzed in a series of 60 patients operated upon over a period of two years. Immediate relief from pain with painless first bowel movement was accomplished in 97 per cent of the patients with very low morbidity rates. All patients were treated on an outpatient basis and had a minimum follow-up of two years without any recurrences. The incidence of sphincter dysfunction is very low and is usually only temporary.

Ambulatory Surgical Procedures↗
PubMedDate not supplied

In vitro activation of irinotecan to SN-38 by human liver and intestine.

BACKGROUND: Irinotecan (CPT-11) is hydrolyzed by carboxyl esterase to the active metabolite SN-38 and oral irinotecan could undergo intestinal and hepatic activation. MATERNALS AND METHODS: Irinotecan was incubated with S9 fractions of human liver and intestinal tissues and the specific activity was determined based on the formation rate of SN-38. RESULTS: Irinotecan was hydrolyzed to SN-38 by hepatic and intestinal S9 fractions with mean (+/- SD) specific activities (pmoles/min/mg) of: liver (8.57 +/- 10.4, n = 8), duodenum (5.06 +/- 3.7, n = 4), jejunum (6.44 +/- 2.8, n = 5), ileum (4.81 +/- 2.4, n = 5), colon (1.93 +/- 1.5, n = 6) and rectum (0.82, n = 1). When incubated with S9 fractions obtained from tumor tissues, there appeared to be a decrease in SN-38 formation compared to matched normal liver and colon tissues. CONCLUSION: Irinotecan undergoes conversion to its active metabolite in human intestinal S9 fractions and there is variability in the extent of SN-38 formation. The localized intestinal activation of irinotecan to SN-38 may provide a rationale for the development of oral irinotecan for gastrointestinal malignancies but could also cause mucosal damage leading to toxicity.

Antineoplastic Agents, Phytogenic↗