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Biomedical subjects

B L Sheppard

Publications and source records attributed to B L Sheppard.

At least 55 records · Page 3Linked to original sources
PubMed1978

Fibrinolysis in decidual spiral arteries in late pregnancy.

The fibrinolytic activity of the intimal cells of decidual spiral arteries and the syncytium of placental villi was studied by electron microscopy in ten normal full-term human pregnancies using a modification of the fibrin slide technique. Endothelial cells lining the intima of the decidual spiral arteries showed a considerably greater fibrinolytic activity than intimal cytotrophoblast and the syncytiotrophoblast showed no activity. The replacement of endothelial cells by an intimal lining of cytotrophoblast, and the presence of cytotrophoblast in the media, appears to play an important role in the reduction of the fibrinolytic activity of the vessel. This inhibition of fibrinolytic activity in the utero-placental arteries may be the physiological mechanism which controls fibrin deposition in these vessels and on the placental villi.

Arteries↗
PubMed1976

The ultrastructure of the arterial supply of the human placenta in pregnancy complicated by fetal growth retardation.

The ultrastructure of the arterial supply of the human placenta was studied in 15 pregnancies with severe fetal growth retardation. There were five patients with essential hypertension and superimposed pre-eclampsia, five patients with pre-eclampsia, and five patients with no hypertension. The patients were delivered by elective Caesarean section and biopsies of the placental bed were taken under direct vision. Extensive placental infarction was invariably present and the degree of infarction reflected the extent of pathological changes in the spiral arteries. In both hypertensive and normotensive patients the spiral arteries and basal arteries of the decidua showed occlusive atheromatous lesions with considerable fibrin deposition and accumulation of lipid-laden cells in both the intima and media of the vessel walls.

Adult↗
PubMed1975

An ultrastructural study of the reversibility of the effects of hypoxia on human trophoblast maintained in organ culture.

Ultrastructural changes in normal human trophoblast maintained in hypoxic organ culture are described. Marked structural changes were noted even after hypoxia for 6 hr. These changes could be partly reversed by reoxygenation after hypoxia for 18 hr or less, but no regeneration occurred when hypoxia lasted for 24 hr or longer. The significance of the vulnerability of trophoblast to hypoxia is discussed.

Carbon Dioxide↗
PubMedDate not supplied

Ultrastructural abnormalities of placental villi in placentae from pregnancies complicated by intrauterine fetal growth retardation: their relationship to decidual spiral arterial lesions.

An ultrastructural study has been made of villi adjacent to decidual spiral arteries exhibiting varying degrees of luminal occlusion in placentae from cases of intrauterine growth retardation. Partially occluded spiral arteries are associated with placental villous syncytiotrophoblast exhibiting extensive budding of surface microvilli, vacuolation of the cytoplasm, clumping of nuclear chromatin and a thickening of the underlying basement membrane. Marked degeneration of the syncytium is present in association with severely occluded spiral arteries. In contrast, the capillary endothelium of the villus retains a normal structure despite degenerative changes in villous Langhan's and stromal cells. The most extensive pathological changes in the placental villi are found distal to completely occluded spiral arteries and consist of complete necrosis of the syncytium and underlying fetal blood vessels, These findings suggest that the occlusive lesions in the maternal uterine vasculature may be the major cause of the infarction and impairment of placental function found in pregnancies complicated by fetal growth retardation.

Arteries↗
PubMedDate not supplied

Serous papillary adenocarcinomas of the ovary display heterogeneity in their response to chemotherapy.

The response of ovarian serous papillary adenocarcinomas to various cytotoxic drugs was examined using the (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) (MTS) cytotoxicity assay. Thirty tumors were collected and organized into four groups according to histologic grade and FIGO stage: stage III, grade 2; stage III, grade 3; stage IV, grade 2; and stage IV, grade 3. The MTS chemosensitivity assay was performed on each tumor to examine the response to cisplatin, paclitaxel, hycamtin and the combination of cisplatin and paclitaxel. Ovarian adenocarcinomas of similar stage and grade displayed varying responses to the same drug. A lower concentration of the drug was often as effective as the peak plasma concentration. For some specimens combination therapy was more effective for inhibiting tumor growth, and for others single-agent therapy gave a better response. A chemosensitivity/resistance profile is recommended before deciding on appropriate chemotherapy.

Antineoplastic Agents↗