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Biomedical subjects

N L Block

Publications and source records attributed to N L Block.

At least 91 records · Page 5Linked to original sources
PubMed1978

Nitrosamine formation in bladder infections and its role in the etiology of bladder cancer.

Dimethylnitrosamine, a powerful carcinogen, is produced in the urine of patients with urinary tract infections of Proteus mirabilis and Escherichia coli when nitrite is present. Treatment with tetracycline antibiotics does not enhance the concentration of this carcinogen but, rather, sharply reduces it. The results emphasize the importance of proper antibiotic therapy for the infections to reduce the possibility of the subsequent development of bladder cancer.

Dimethylnitrosamine↗
PubMed1978

Inhibition of growth and guanylate cyclase activity of an undifferentiated prostate adenocarcinoma by an extract of the balsam pear (Momordica charantia abbreviata).

We have recently described the presence of a guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] inhibitor (GCI) in an aqueous extract of the balsam pear (Momordica charantia abbreviata). Because the guanylate cyclase-cyclic GMP system is though to be involved in cell growth, DNA and RNA synthesis, and possible malignant transformation, we examined the effect of the aqueous extract containing GCI on an undifferentiated adenocarcinoma of the rat prostate and concanavalin-A-stimulated [3H]thymidine incorporation into cultured splenic lymphocytes, a process thought to be mediated by cyclic GMP. The results demonstrate that the extract of the balsam pear blocks both the growth of the rat prostatic adencarcinoma in vitro and [3H]thymidine incorporation into DNA. DNA histograms from flow cytometry indicated that the extract containing GCI inhibited in the G2 + M phase of the cell cycle, a presumed locus of cyclic GMP effects. In addition, guanylate cyclase activity was significantly greater in the tumor than normal prostate tissue and was decreased by the extract containing GCI. Cyclic GMP levels in the tumor in culture wer also decreased by addition of the extract. It remains to be determined whether or not the anti-tumor agent and GCI are the same substance.

Adenocarcinoma↗
PubMed1978

The initiation, progress, and diagnosis of dog bladder cancer induced by 4-aminobiphenyl.

Twenty-four beagles received 4-aminobiphenyl orally 5 days a week for 3 years. The dogs were examined cytoscopically at frequent intervals. Biopsy and surgery were performed according to predetermined criteria. Three basic patterns of carcinogen responses were seen. Negative or minimal disease was seen in four dogs. Of these, two remained completely free of neoplasia. Eleven dogs progressed slowly in their development of neoplasia with minor fluctuations in development. A rapidly progressive pattern was observed in the remaining nine dogs. A large variance in the time of onset of the first positive diagnosis of neoplasia was seen. Eleven dogs underwent surgery ranging from tumor sampling to cystectomy plus ureterosigmoidostomy. Histologic types and grades and patterns of metastasis as well as several other characteristics seemed to parallel closely human bladder cancer.

Adenocarcinoma↗
PubMed1978

Further experience with chemotherapy in the Dunning prostatic adenocarcinoma.

A number of chemotherapeutic agents, including L-asparaginase, actinomycin D, chloroethylcyclohexy-nitrosourea, 5-flourouracil, cyclophosphamide, hydroxyurea, cis-platinum, adriamycin and methotrexate, alone and in combination and at variable dose levels, were applied against the Dunning R3327 rat prostatic adenocarcinoma-subline G. We found a continuing parallel between responses of the human and rat tumors and conclude that the usefulness of this animal model as a screening system for agents against the human tumor is further supported.

Adenocarcinoma↗
PubMed1977

Chemotherapy of the transplantable adenocarcinoma (R-3327) of the Copenhagen rat.

A number of therapeutic agents including L-asparaginase, Actinomycin-D, CCNU, Hydroxyurea, 5-FU, Cis-platinum, Cyclophosphamide, orchiectomy, Adriamycin and DES alone and in various combinations has been applied against the Dunning R-3327 rat prostatic adenocarcinoma subline G. We have found a parallel between the results of this study and those of similar therapeutic application to the human tumor. We conclude that this animal model may prove to be a useful screening system for agents against human prostatic cancer.

Adenocarcinoma↗
PubMed1976

Simultaneous surgical management of bilateral hypernephroma: an alternative therapy.

Herein are reported 2 cases of bilateral hypernephroma treated by simultaneous bilateral partial hephrectomy. One patient died of a myocardial infarction 3 years postoperatively and the other is well 30 months postoperatively. Bilateral partial nephrectomy is proposed as an alternative to bilateral nephrectomy and homotransplantation.

Adenocarcinoma↗
PubMed1975

Urinary bladder carcinogenesis in the dog: preliminary studies on cellular immunity.

The immunologic status of dogs undergoing bladder carcinogenesis with 4-amino-biphenyl and normal littermate controls is being evaluated. Studies using blastogenic transformation, nonimmune cytotoxic reactions, and rosette formation have revealed that dogs possess lymphocytes that have some properties similar to those of B and T cells of other species. Since tumors are now just appearing and hence are not yet available for specific immunologic determinations, the assessments had to be limited for the present to other types of antigens and mitogens (yeast, red blood cells and plant lectins). No major changes in reactions of cells from the carcinogenized animals have yet been observed during the preneoplastic phase as measured by phagocytosis, migration inhibition, or cytotoxicity tests, although a trend to lower blastogenic responses was noted. It yet remains to be seen whether lower lymphocyte responses to mitogens in carcinogenized dogs are of prognostic value for the early detection of tumors of the bladder.

Aminobiphenyl Compounds↗