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Biomedical subjects

D Francis

Publications and source records attributed to D Francis.

At least 145 records · Page 8Linked to original sources
PubMed1980

Development of virus non-producer lymphosarcomas in pet cats exposed to FeLv.

Naturally occurring oncoviruses of several species are transmitted contagiously and cause lymphosarcoma (LSA) or leukaemia in their hosts. All naturally occurring oncoviruses replicate in vivo in the tumours they induce or, as with bovine leukaemia virus, can be isolated from tumour cells grown in short-term cell culture. However, we have shown that feline leukemia virus (FeLV) is not present in a significant minority of pet cats that develop LSA. Unlike experimentally induced virus-negative leukaemias and sarcomas of other species, LSA cells from FeLV-negative LSA cats lack any FeLV proteins, including p15 or p12, and complete functional copies of FeLV provirus and thus do not produce FeLV when grown in cell culture. Thus, except for FeLV, the naturally occurring animal leukaemogenic oncoviruses seem to induce only virus-producing lymphoid tumours. Our earlier findings prompted a study to determine the frequency of occurrence of FeLV non-producer (NP) LSA in pet cats and whether NP LSAs develop in cats exposed to FeLV. We report here epidemiological data which indicate that development of NP LSAs in pet cats is associated with exposure to FeLV and suggest that FeLV may be the aetiological agent for FeLV NP feline LSAs. Thus, feline NP LSAs may be suitable for studying the potential viral aetiology and mechanism of leukaemogenesis of human lymphoid tumours in which no oncoviruses have, as yet, been proved to cause the disease.

Animals↗
PubMed1980

Oxatomide: in vivo assessment of antagonistic activity, and effects on histamine release and enzymatic histamine degradation in skin.

The antagonistic activity of oxatomide, and its effects on evoked histamine release and histamine-N-methyl transferase activity in skin, have been studied. Oxatomide antagonizes H1 activity in a dose-dependent but non-competitive manner. It also shows some atropine-like activity. Oxatomide did not cause detectable inhibition of antigen-stimulated histamine release from skin slices of sensitized guinea-pigs although the possibility that oxatomide may cause weak inhibition could not be excluded. In the presence of low concentrations of histamine, oxatomide suppressed human skin histamine-N-methyl transferase, but in the presence of higher substrate concentrations it enhanced activity of this enzyme. These observations, which were limited by the poor solubility of oxatomide in aqueous media, should encourage further in vivo studies of oxatomide's histamine-suppressing properties in the human subjects.

Acetylcholine↗
PubMed1980

Pulmonary blastoma. A clinico-pathological study of eleven cases.

Eleven cases of pulmonary blastoma are presented, the largest series reported from one department to date. The frequency of pulmonary blastoma was found to be 0.5 per cent of all primary lung cancers. The variegated histologic appearance of the tumour and the diverging metastatic pattern are described in detail. In light of the complex histological picture and the biological behavior a suggestion of the histogenesis of pulmonary blastoma is attempted.

Aged↗
PubMed1978

Transthoracic aspiration biopsy. Occurrence of non-neoplastic cells in biopsies from malignant and non-malignant lesions.

In the search for a possible distinction between false and true negative biopsies, an analysis of the distribution of the non-neoplastic cells has been performed in 100 randomized transthoracic aspiration biopsies in so many histologically verified cases. Aspiration biopsies from malignant lesions often contain many giant cells, alveolar epithelial cells, and mast cells, but a significant differences was only found for the mast cells. A negative biopsy containing many inflammatory cells and mast cells and showing a pronounced degree of necrosis may represent a chronic obstructive pneumonitis, and such a finding should always prompt further investigation.

Biopsy, Needle↗
PubMed1978

Transthoracic aspiration biopsy. The distribution of the non-neoplastic cells in aspiration biopsies from different types of malignant lung tumours.

In an earlier paper concerning classification of aspirated May-Grünwald-Giemsa stained malignant tumour cells from lung lesions, we found the sensitivity to be 80--95 per cent for adenocarcinomas, undifferentiated carcinomas and small cell carcinomas. For epidermoid carcinomas the sensitivity was only 64 per cent. It was therefore found of interest to see if a registration of the non-neoplastic cells could be an aid in the cytological tumour cell classification. An analysis has been performed of the distribution of the non-neoplastic cells in 71 aspiration biopsies from six different types of malignant lung tumours. A variegated population of many and different types of infalmmatory cells, mast cells and alveolar epithelial cells was a characteristic finding in biopsies from neoplasms with an epidermoid differentiation.

Biopsy, Needle↗
PubMed1978

Transthoracic aspiration biopsy. The occurrence and significance of alveolar epithelial cells.

Alveolar epithelial cells in pulmonary aspirates sometimes appear with a pronounced nuclear atypism which may give rise to diagnostic difficulties. An analysis has been performed of the occurrence and morphology of alveolar epithelial cells in a series of histologically-verified transthoracic aspiration biopsies not containing clear-cut malignant tumour cells. Alveolar epithelial cells, as well as atypism of these cells, are more often seen in biopsies from histologically malignant cases than in benigh cases. Their presence in a pulmonary aspirate may be due to a chronic obstruction atelectasis. In cases with tumour-like configuration of the alveolar epithelial cells, an open pulmonary biopsy is recommended, as it seems impossible to decide whether such findings represent a neoplastic or a reactive process.

Adolescent↗
PubMed1977

Enzymatic histamine degradation by human skin.

1. Degradation of histamine by homogenized human skin in vitro, in the presence of the cofactor S-adenosyl methionine, indicates the presence of the histamine metabolizing enzyme histamine-N-methyl transferase in human skin. Under the experimental conditions described, no significant histamine degradation by diamine oxidase was observed. 2. The enzyme activity is temperature-sensitive with an optimum at 37 degrees C. The enzyme is stable in in intact excised skin at -20 degrees C, but unstable in homogenized skin at this temperature. 3. Little or no enzyme activity is present in mid- or deep dermis, but the distribution of the enzyme between superficial papillary dermis and epidermis is uncertain. 4. The presence of a potent histamine degrading mechanism raises the possibility that histamine-N-methyl transferase activity may be an important modulating factor in histamine-mediated skin disorders.

Chromatography, Thin Layer↗
PubMed1977

The breeding system of Polysphondylium pallidum, a cellular slime mold.

A mating type analysis was performed on 231 isolates of the cellular slime mold, Polysphondylium pallidum found in 61 samples collected in eastern North America between northern Florida and sourthern Canada. Seventy-eight percent of the isolates belonged to one of 2 mating types; 18% were incapable of mating with any partner; 3% were homothallic; and 1%, consisting of 2 isolates from a Florida sample, belonged to a separate breeding group. It is suggested that the majority of isolates represent a species capable of local genetic adaptation to a niche, the parameters of which undergo considerable variation over space and time.

Ecology↗