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Biomedical subjects

M Pollard

Publications and source records attributed to M Pollard.

At least 109 records · Page 6Linked to original sources
PubMed1979

Promotional effect of sodium barbiturate on intestinal tumors induced in rats by dimethylhydrazine.

Noninbred Sprague-Dawley rats were administered 1,2-dimethylhydrazine hydrochloride (DMH) by gavage or methylazoxymethanol acetate by sc inoculation. Thereafter, one group was given water to which 0.1% sodium barbiturate was added, and the other was given drug-free water. They were examined 20 weeks after onset of the experiments. A direct relationship was noted between dosage of DMH and numbers of intestinal tumors induced in the rats. The rats provided with sodium barbiturate-supplemented water developed more intestinal tumors than did those that drank drug-free water.

Animals↗
PubMed1978

In vitro effects of lipoprotein-associated cytotoxic factor on rat prostate adenocarcinoma cells.

As assayed by the colony inhibition technique, sera from rats at an advanced stage of pregnancy were cytotoxic to a number of tumorigenic and "nontransformed" cell lines. The cytotoxic effect is not species specific. Primary fetal rat kidney cells were not susceptible to this cytotoxic effect. The level of demonstrable cytotoxicity in sera rose gradually as gestation advanced; it peaked at 48 hr before parturition and disappeared thereafter. Sera from control nonpregnant rats were not cytotoxic. The cytotoxic factor(s) in sera was demonstrable only in the very low-density lipoprotein (VLDL) (hydrated density less than 1.006 g/ml) fraction. Reconstitution studies suggest that: (a) inhibitors which usually mask the cytotoxic actitivity of VLDL in whole serum, are present; and (b) pregnancy initiates enhanced VLDL synthesis, which exceeds the masking effect. The possible role of this cytotoxic VLDL in host defense against neoplasia is discussed.

Adenocarcinoma↗
PubMed1978

Induction of colon tumors in 1,2-dimethylhydrazine-resistant Lobund Wistar rats by methylazoxymethanol acetate.

Sprague-Dawley and Lobund Wistar rats, which were sensitive and resistant to induction of colon tumors by 1,2-dimethylhydrazine (DMH), respectively, were treated with methylazoxymethanol (MAM), the product of DMH metabolism by the microsomal mixed-function oxidase system. Although the colon tissue in both stocks of rats had similar NAD+-dependent dehydrogenase activities that are considered necessary to activate MAM to an ultimate carcinogen, still a sevenfold greater incidence of colon tumors was found in the Sprague-Dawley rats, and their tumors were more extensive. The results indicated that the difference in susceptibility to colon tumor induction between the rat stocks was partially related to metabolic activation of the DMH and to other, as yet undetermined, endogenous factors.

Adenocarcinoma↗
PubMed1977

The Erlangen magnetic colostomy control device: technique of use and results in 22 patients.

The evolution and general principle of the Erlangen magnetic ring colostomy device are described and its practical use illustrated by reference to a personal series of 22 patients treated with the device. Analysis of the functional results obtained in 13 of these cases, who were assessed after at least 3 months' trial, shows that only 3, or at most 4, could be considered to have achieved worth-while continence, but there are grounds for believing that these results might be improved a little by more stringent selection of patients for the procedure and by employing a more meticulous technique for implanting the rings.

Colostomy↗
PubMed1977

Investigations on prostatic adenocarcinomas in rats.

Metastatic prostate adenocarcinomas, derived from aging germfree Wistar rats, have been propagated in rats and in tissue culture. A protocol has been developed and demonstrated for assay of treatments which retard or which accelerate the rate and extent of tumor growth and of metastasis in tumor-bearing rats. The pattern of spread has been retarded by cyclophosphamide, aspirin, indomethacin, and Corynebacterium parvum. The spread pattern has been accelerated by oral administrations of sodium barbiturate.

Adenocarcinoma↗
PubMed1977

In vitro propagation of prostate adenocarcinoma cells from rats.

Two rat adenocarcinomas were physically dispersed and propagated in vitro. Epithelial and fibroblast cell lines were cloned from them and the monolayer cell lines derived therof were further characterized. The cells produced acid phosphatase in early in vitro cell passages, and later they turned negative. Fibroblast-like cells produced no tumors when implanted in syngeneic Lobund Wistar rats, but as few as 10 epithelial cells produced metastasizing adenocarcinomas in them. A third prostate tumor has yielded a line of epithelial cells which reproduced the original tumor type in inoculated rats, but the cells have not yet been characterized. Rat prostate adenocarcinomas provided a useful model system for in vitro and in vivo studies on prostate cancer and on metatasis.

Acid Phosphatase↗
PubMed1976

In vivo host immune to a tumor-specific transplantation antigen induced by Rous sarcoma virus.

We examined the host immune response to a tumor-specific transplantation antigen (TSTA) induced by Rous sarcoma virus (RSV) In vivo. In contrast to previous in vitro studies, the present investigation demonstrated in vivo host immunity of the TSTA 10-55 days after tumor inoculation. Immunity to the TSTA appeared specific, since the homologous RSV tumor was rejected. whereas the heterologous tumor grew progressively. No generalized suppression of cell-mediated or hymoral immunity was shown, because tumor-bearing hosts retained the ability to reject heterologous tumor cells and mounted a normal plaque response to sheep red blood cells. Although alpha-globulin levels were elevated, they did not appear to affect the host's immunity to the growing tumor or to heterologous antigens. Assoicated with the progressively growing tumor was the appearance in the serum of a fetal antigen with characteristics of an alpha-2 acute phase protein.

Alpha-Globulins↗
PubMed1976

Allogeneic bone marrow chimerism in germ-free mice. IV. Therapy of "Hodgkin's-like" reticulum cell sarcoma in SJL mice.

"Hodgkin's-like reticulum cell sarcoma develops spontaneously in most SJL mice. Germ-free and conventional SJL mice bearing advanced reticulum cell sarcoma were treated with X-irradiation and transplantation of bone marrow from SJL or C3H/He donors. The 120-day survival rate of germ-free mice receiving allogeneic bone marrow (70%) exceeded that of all control groups; more importantly, germ-free mice that survived more than 4 months after treatment with allogeneic cells had no evidence of neoplastic lesions when killed. The germ-free environment effectively prevented graft-versus-host disease that was lethal to conventional mice. The results of these experiments offer additional evidence that bone marrow transplantation can be used as a therapeutic tool for spontaneous murine neoplasms.

Animals↗
PubMed1976

Bacterial decontamination and antileukemic therapy of AKR mice.

Four nonabsorbable antibiotics (streptomycin, neomycin, bacitracin, and amphotericin B) and a germicidal dip solution (Zephiran chloride/water) were used to eliminate all the detectable bacteria from conventional AKR mice. Control mice were not decontaminated and were used as such. When antibiotic-decontaminated and control mice developed clinical manifestations of spontaneous lymphatic leukemia, each was treated for the disease with an antitumor drug (cyclophosphamide [CP]) at weekly intervals. With the decontamination procedure, mice of each of the two groups became bacteria-free after 16 weeks of continuous oral administration of the antibiotics and two separate germicidal dippings. All decontaminated mice remained free of bacteria throughout the experiment. The bacterial flora of the control mice remained unaltered. With CP therapy, the mean survival time of the female decontaminated mice was 65 days, whereas that of male mice was 218 days. The average survival time of the CP-treated control leukemic mice was 51 days. Untreated decontaminated or control mice usually died of leukemia within 7 days after the onset of symptoms of leukemia. Although CP therapy was not curative, it did prolong the life expectancy of the decontaminated mice significantly.

Amphotericin B↗
PubMed1976

Ultrastructural cytology of prostate carcinoma cells from Wistar rats.

Cells from spontaneous adenocarcinomas of the prostate (Pollard, M.: J. Natl. Cancer Inst. 51: 1235, 1973) in aged Lobund Wistar rats were examined by electron microscopy. Cytologic structures of the rat prostate tumor cells resembled analogous structures from human prostate tumor cells. These findings support the prospect that the rat prostate tumor will provide a model system of prostate cancer in man.

Adenocarcinoma↗
PubMed1975

Inactivation of viruses and bacteria by ozone, with and without sonication.

Selected organisms with public health significance were placed in a reaction chamber for treatment by ozonation, by ozonation and sonication, by sonication, or by sonication during oxygenation. Vesicular stomatitis virus, encephalomyocarditis virus, GDVII virus, Staphylococcus aureus, Pseudomonas fluorescens, Salmonella typhimurium, enteropathogenic Escherichia coli, Vibrio cholerae, and Shigella flexneri were inactivated by treatment with ozone. When microorganisms were suspended in phosphate-buffered saline, they were inactivated rapidly by treatment with ozone. However, microorganisms suspended in secondary effluent from a wastewater treatment plant required longer contact times with ozone for complete inactivation. Simultaneous treatments by ozonation and sonication reduced the contact time for complete inactivation of microorganisms in secondary effluent. Treatment by sonication alone or sonication and oxygenation did not inactivate microorganisms. Therefore, the simultaneous treatment of microorganisms in secondary effluent with ozone and sonication resulted in a synergistic effect.

Animals↗
PubMed1975

Effects of cholestyramine on 1,2-dimethylhydrazine-induced enteric carcinoma in germfree rats.

Oral administration of 1,2-dimethylhydrazine (DMH) induced intestinal neoplasms in germfree rats. A supplement of 2% cholestyramine resin in the diet increased the frequency of DMH-induced intestinal tumors and accelerated malignant transformation. Bile acids in the cecal content were determined with and without cholestyramine in order to obtain a correlation between the bile acid metabolism and the enteric carcinogenesis.

Adenocarcinoma↗
PubMed1975

Transplantable metastasizing prostate adenocarcinomas in rats.

Three spontaneous prostate adenocarcinomas from aged, randombred, germfree Lobund Wistar rats were transplanted, without change, through several series of conventional Lobund Wistar rats. One tumor type differed histologically from the other two tumor types. Rats with subcutaneously transplanted tumors developed metastatic tumors in the lymph nodes and lungs. No microbial agent was detected in the tumor cells.

Adenocarcinoma↗