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Biomedical subjects

A Siegal

Publications and source records attributed to A Siegal.

64 records · Page 4Linked to original sources
PubMed1979

[Whipple's disease].

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Anti-Bacterial Agents↗
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In vitro and in vivo effects of photodynamic therapy on murine malignant melanoma.

BACKGROUND: The role of photodynamic therapy (PDT) in the treatment of malignant melanoma is not well defined, nor is it known whether the dark melanoma cells absorb the light used in PDT. METHODS IN VITRO STUDIES: 2 x 10(5) B16 murine melanoma cells were incubated with aluminum phthalocyanine (AlpcS4, 2.5 mg/kg) and were then subjected to photoradiation (50, 100 or 200 J/cm2). Viability was then assessed. In vivo studies: HISTOLOGY: C57/B1 mice received 2 x 10(5) B16 cells subcutaneously and were randomized into study (PDT) and three control groups. AlpcS4 2.5 mg/kg was injected intraperitoneally and the mice were exposed to light (100 J/cm2). After 24 hours they were sacrificed and underwent autopsies. Survival: 40 mice were randomized into PDT (40 J/cm2) and control groups and were monitored for 50 days. Tumor growth: 40 mice were randomized into one control and three treatment groups (PDT on day 3, 6, or 12 after injection with B16 cells), and were monitored for 50 days. Temperature: Tumor temperatures before and at the end of PDT were recorded. RESULTS IN VITRO STUDIES: PDT caused a decrease in cell viability to 15.5 +/- 0.7%, 11.5 +/- 2.1%, and 1.5 +/- 0.7% (at 50, 100, and 200 J/cm2, respectively; P < .001). A significant reduction in thymidine incorporation was noted at all energy levels. In vivo studies: HISTOLOGY: PDT caused massive tumor necrosis. Survival: PDT prolonged the survival of mice (41 +/- 13.4 days) compared to controls (15.8 +/- 3.8 days, P < .001). Tumor growth: 31 days after injection with B16 cells, the tumor size was 2.6 +/- 0.3 cm in the control group and 1.6 +/- 0.2, 0.9 +/- 0.3, and 1.0 +/- 0.4 cm in the PDT groups (days 3, 6 and 12, respectively; P < .01). Temperature: PDT increased skin temperature to 42.8 degrees C +/- 1.3 degrees C, 45.3 degrees C +/- 3.5 degrees C, and 51.7 degrees C +/- 2.7 degrees C at 40, 60, and 100 J/cm2, respectively (P < .01). CONCLUSIONS: Photodynamic therapy was found to have significant effects in experimental melanoma in mice. The role of PDT in human melanoma remains to be studied.

Animals↗
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Prognostic significance of p53 and ras p21 protein expression in surgically treated non-small cell lung carcinoma.

BACKGROUND AND OBJECTIVE: The prognosis of surgically treated non-small cell lung carcinoma (NSCLC) varies even after careful selection of the patients; the conventional grading and staging system is often deficient in determining which cases will profit best from surgery. Additional techniques are needed to permit better prognostic evaluation. METHODS: In this research, 2 markers of cellular proliferation, p53 and ras (p21) proteins were examined. The material used was from the same series reported previously which were immunostained with different cytokeratin markers for the same purpose. Immunohistochemical stainings of p53 and p21 were performed on the paraffin sections of 88 NSCLC specimens: 45 squamous cell, 22 adeno- and 21 large or undifferentiated carcinomas. RESULTS: At stage I, positive or negative stains of p53 and p21 provided no prognostic information since they had similar 5 year survival rates of approximatively 50% which is similar to the mean predicted survival rate for stage I. In this group as well, there was no significant difference in immunostaining, either in relation to the histological type or grade of the tumors. At stage III-IV, we found a trend, which, however, was not statistically significant, between positive immunostains of p53 and p21 proteins and longer survival. CONCLUSIONS: These results vary from our previous study on the expression of the differentiation marker cytokeratin 18, which showed that positive staining of tumor cells was associated with a statistically significant poorer prognosis at stage I regardless of histological types.

Aged↗
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The fate of the freeze-preserved xenograft: an experimental study on rabbits, cats, and dogs.

Freeze-preserved allografts have been used successfully in patients for vascular peripheral replacement, dialysis, and chemotherapy. Freezing of veins seems to decrease or abolish antigenicity by decreasing the viable cellular components of the grafts. To confirm its acceptance and consequently, the high patency rates of freeze-preserved vein grafts, we inserted segments of human veins preserved at -80 degrees Centigrade as arterial substitutes into rabbits, cats, and dogs and studied the morphological changes of these xenografts up to 2 years. In all the groups, the patency rate was satisfactory. In rabbits and dogs, the cellular inflammatory reaction around the grafts and suture lines disappeared after a few weeks; the endothelium was reconstructed at 2 months and a poorly differentiated cellular fibro-collagenous wall with prominent hyalin matrix was observed. In cats, however, the histio-lymphocytic infiltrate persisted in functioning grafts up to 2 years associated with adjacent prominent vascular and nerve proliferation. It is suggested that this inflammatory reaction has no deleterious effect on the graft; on the contrary, it promotes its neovascularisation and innervation. The cat proved to be a good animal model for vascular surgical experiments. Our study proved the poor antigenicity of freeze-preserved venous xenograft. It could, in the future, be used for human arterial substitutes.

Animals↗
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Bone marrow and peripheral blood modifications in C57BL mice administered with cyclophosphamide and levan.

The effects of cyclophosphamide (CY) and levan at low (0.1 mg) and high (10 mg) doses (previously found to inhibit and stimulate, respectively, B16 melanoma growth) were studied. in single and combined administration, on the blood and bone marrow of C57BL mice. Very marked changes in the cellular composition of blood and bone marrow were induced by the various treatments. CY caused a sharp depletion of leukocytes in blood and bone marrow followed by a restoration of granulocytes while lymphocytes remained low. Levan caused a sharp dose-dependent depletion in bone marrow lymphocytes. Blood lymphocytes were not affected, however, by the polysaccharide. With the high levan dose, after a temporary granulocytopenia and monocytopenia, prominent granulocytosis was observed. While CY affected equally the different types of cells, levan decreased the number of lymphocytes and erythroblasts to a greater degree than the number of granulocytes. In the combined CY-levan treatments, the low levan dose generally attenuated the suppressive effect of CY, while the high concentration aggravated it.

Animals↗
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Freeze-preserved vein grafts and atherosclerosis. An experimental study.

Histopathological changes of three types of vein grafts were studied. Freeze-preserved, fresh human grafts and autografts were inserted as patches in the aorta of rabbits on regular and variable cholesterol diets. In all grafts the endothelium and adventitia were reconstituted after a few months. In the wall, smooth muscle and elastic tissue were markedly diminished and poorly oriented with accompanied collagenisation. Cholesterol diet led to progressive fat and/or calcium deposition with subintimal proliferation in the autografts and fresh xenografts. In contrast this was seen to a much lesser degree and later in freeze preserved xenografts, even on higher cholesterol diets. Deep freezing considerably reduces the cellularity of the graft and its metabolic ability to accumulate lipids. Freeze-preserved veins seem to be a suitable graft for vascular reconstructions in severely atherosclerotic patients and compare favorably with vein autografts.

Animals↗