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Biomedical subjects

D M Taylor

Publications and source records attributed to D M Taylor.

At least 235 records · Page 13Linked to original sources
PubMed1978

Maintenance of biological and biochemical characteristics of human colorectal tumours during serial passage in immune-deprived mice.

The effect of serial passage in immune-deprived mice on certain biological and biochemical parameters has been studied in a series of 6 human colorectal tumour xenografts. Histological integrity is maintained for up to 10 serial passages, together with production of epithelial mucins and carcinoembryonic antigen. Passaged tumours retain human lactate dehydrogenase and glucose-6-phosphate dehydrogenase isoenzyme patterns and a human chromosome constitution. The induction of a murine tumour has been identified in this system, and the importance of routine checks for the presence of human tissue during serial passage is stressed.

Animals↗
PubMed1978

Growth characteristics of human colorectal tumours during serial passage in immune-deprived mice.

The growth characteristics of 6 human colorectal tumours have been examined during serial passage in both male and female immune-deprived mice. Exponential growth is a characteristic feature, especially on very early passages. Growth rates in 5 out of the 6 tumour lines increase during the first few transplant generations. This is accompanied by a shorter exponential growth phase and an increased slope of the growth curves. Lag phases and growth rates for individual tumours are variable within a passage. Growth rates for tumours maintained within the same host are similar, and are at least partially influenced by the host. In one tumour line examined in detail, the increased growth rate is attributable to a decreased cell-loss factor, and the difference in growth rate between human colorectal tumours and their corresponding xenografts may therefore largely be due to a difference in the contribution of this factor.

Animals↗
PubMed1978

Rationalisation and modification of a germ-free isolator design.

A modified design of polyvinyl chloride isolator, suitable for small laboratory animals utilises room space more effectively than previous models and is particularly useful where accommodation is restricted. The standard attachments and ancillary equipment used with other flexible isolators are compatible with the modified isolator.

Animals↗
PubMed1978

Antimetastatic action of some triazene derivatives against the Lewis lung carcinoma in mice.

Two dimethyltriazenoimidazoles, DTIC and BRL 51308, and a benzenoid dimethyltriazene, CB 10286, have been examined for their effects in mice bearing Lewis lung carcinoma. A slight reduction of primary tumor growth was found after treatment with DTIC and BRL 51308, whereas CB 10286 caused no significant effect. On the contrary, all the tested compounds sharply reduced the number of lung metastases and also resulted in a high proportion of animals free of metastases at death. No significant cytotoxic effect of the triazenes was observed in small established pulmonary tumors, as determined by evaluating the effects of treatment on the fractional incorporation of 3H-TdR into DNA of the lung colonies. These results are in contrast to those obtained with a purely cytotoxic agent, cyclophosphamide, and indicate that all three triazene derivatives tested have selective antimetastatic properties.

Animals↗
PubMed1978

The effect of haematoporphyrin derivative on the uptake of 67Ga, 59Fe and 65Zn in tumours.

The effect of prior administration of haematoporphyrin derivative on the uptake in tumours of 67Ga, 59Fe and 65Zn has been studied in tumour-bearing rats and mice. An approximately two-fold increase in the uptake of 67Ga was observed in the August 15 rat tumour when the nuclide was administered 17 to 24 hr after haematoporphyrin. No increase in the uptake of 67Ga occurred in three mouse tumours. Haematoporphyrin administration did not affect the uptake of 65Zn and 59Fe in any of the tumour systems. It is concluded that the presence of haematoporphyrin does not markedly increase the ability of tumours to accummulate metallic radionuclides.

Animals↗
PubMed1977

Effects of cytotoxic agents on TdR incorporation and growth delay in human colonic tumour xenografts.

The relationship between the utilization of 3H-thymidine in situ ([3H]-TdR fractional incorporation or TFI) and tumour growth delay after treatment with various cytotoxic agents has been examined. It is shown that (a) it is not possible to predict tumour growth delay, or to select the most effective agent, from changes in TFI 1 day after treatment; (b) there is a good correlation between tumour growth delay and the time for recovery of TFI to the pretreatment level; (c) there is a relationship within a tumour line between the depression of TFI 4 days after treatment and growth dealy induced by the same treatment. This relationship appears to be independent of the mechanism by which the agent exerts its cytotoxic effect.

Animals↗
PubMed1977

Fractional incorporation of [3H]thymidine and DNA specific activity as assays of inhibition of tumour growth.

The Fractional Incorporation (FI) of [3H] thymidine ([3H]TdR) has been examined in small lung tumours after cyclophosphamide (CY) treatment in vivo and compared to the DNA specific activity (SA) at different times after treatment. FI was found to correlate with the incidence of labelled cells after treatment, whereas SA did not, due to the loss of DNA from drug-killed cells 72 h after treatment. The FI is independent of the precursor concentration in the tissue, and therefore may give a better index of DNA synthesis in irregularly perfused tissues than SA. Following either CY or 60Co radiation treatment, the time necessary for FI to reach the pretreatment level is quite similar to the growth delay measured for the FI depression 45 h after treatment and growth delay has been established in the Lewis lung tumour, which would allow the prediction of growth delay induced by another agent to be made within 2 days of treatment.

Animals↗
PubMed1977

Studies with cyclophosphamide labeled with phosphorus-32: nucleic acid alkylation and its effect on DNA synthesis in rat tumor and normal tissues.

The gross distribution of levels of [32P]cyclophosphamide ([32P]CY) in August female rats was similar in tumor, intestinal mucosa, spleen, bone marrow, and striated muscle tissue, with slightly higher levels in liver and kidney tissue. A triphasic association with nucleic acids was found and actual alkylation of DNA and RNA reached a maximum of 48 hours post treatment. There was no evidence of 32P-label reutilization that could have accounted for prolonged alkylation. We found that 100 mg CY/kg suppressed the incorporation of [3H]thymidine, [3H]deoxyuridine, and [14C]sodium formate into the DNA of the BICR-A15 carcinoma for at least 10 days. This correlated well with the observed regression of tumor volume. Bone marrow and intestinal mucosa, two tissues which limit chemotherapuetic treatment of the tumor, were less affected by 100 mg CY/kg. Bone marrow had regained normal levels of DNA precursor incorporation by 5 days, and intestinal mucosa had regained normal levels by 3 days. Results indicated that this differential in recovery time may assist in the successful scheduling of vital tissue-sparing drug regimens.

Alkylation↗
PubMed1977

The effects of supplementary nicotine in regular cigarette smokers.

Blood nicotine levels were measured in eight subjects over a 5-week period, while smoking normally, while smoking and chewing gum containing 2 mg nicotine, and while smoking and chewing placebo gum. Despite a small but significant rise in blood nicotine levels during the period of the nicotine gum chewing (mean 35.3 ng/ml) compared with placebo (mean 28.9 ng/ml) and control (mean 26.3 ng/ml), cigarette consumption butt lengths, filter nicotine and blood carboxyhaemoglobin levels did not change indicating that there had been no significant changes in smoking patterns. The reasons for this failure to demonstrate an effect are discussed. It is concluded that the dose of nicotine used was probably not adequate to produce an effect.

Administration, Oral↗