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Biomedical subjects

D M Phillips

Publications and source records attributed to D M Phillips.

At least 163 records · Page 9Linked to original sources
PubMed1978

Human semen as a source of epithelial cells for culture.

When washed cells from human semen samples were plated out, epithelial cultures were obtained. The human ejaculates used as starting material contained, in addition to spermatazoa, 10(3) to 10(7) cells of other types, including granulocytes, macrophages, lymphocytes, spermatocytes and epithelial cells. Although no fractionation of cell types was attempted, semen samples yielded epithelial cultures uncontaminated by fibroblasts. The cultured cells appeared characteristically epithelial with a polygonal shape, interdigitating cell membranes, and desmosomes. ABH blood-group antigenic determinants of the donor were expressed with variable frequency as a surface antigen on these cells. About half the trials gave some cell attachment. Most cultures remained as small, tight colonies, but a few reached confluency in about 5 weeks and could be subcultured successfully. Cell proliferation, as monitored by (3H) thymidine incorporation into nuclear macromolecules, ceased in less than 2 months.

Antigens, Surface↗
PubMed1978

Juvenile polyp in a 10-month-old infant.

A 10-month-old boy had episodes of apparent colic with bloody diarrhea. On investigation after prolapse of a rectal mass, a pedunculated polyp was found and removed by transanal ligation. The abdominal pain had been caused by the polyp intussuscepting the sigmoid colon into the rectum. Although rectal bleeding in children under age 1 is rarely caused by rectal polyps, physicians should consider this diagnosis in children of any age when recurrent colic and blood-streaked diarrhea occur.

Gastrointestinal Hemorrhage↗
PubMed1977

Leukocyte emigration and migration in the vagina following mating in the rabbit.

Within 45 minutes after mating in the rabbit, numerous heterophil leukocytes adhere to the endothelium of venules in the vagina. Initial association appears to occur via small protuberances from the leukocyte which fit into small indentions in the endothelial cell. Following adherence, leukocytes flatten and pass between endothelial cells. A regular intercellular space separates the leukocyte from the endothelial cells. Leukocytes subsequently migrate through the connective tissue to the epithelium. By three hours postcoitus, the region beneath the basement lamina of the vaginal epithelium is crowded with numerous juxtaposed leukocytes. Leukocytes subsequently migrate between epithelial cells into the vaginal lumen where they actively engulf spermatozoa. Spermatozoa appear to be ingested head first. Numerous small filaments are observed in the leukocyte cytoplasm in the region adjacent to the sperm head. Degranulation of azurophyl granules follows sperm uptake. The leukocyte response can be elicited either by spermatozoa (from the epididymis) or by semen (from vasectomized bucks), but is not elicited by ovulation (with human chorionic gonadotropin). It is suggested that the response may be initiated because the vagina does not distinguish between semen, spermatozoa and bacterial infection.

Animals↗
PubMed1977

Phagocytosis of spermatozoa by the rabbit vagina.

Twenty-four hours after mating in the rabbit, numerous spermatozoa are observed attached to the surgace of the vaginal epithelium. Spermatozoa appear to be attached by their heads to microvilli of the simple columnar cells which compose the vaginal epithelium. Spermatozoa are taken up by the epithelial cells, and they are found within the cells in various stages of degeneration up to seven days after mating. Epithelial cells frequently appear to be filled with numerous vacuoles containing sperm components in various stages of degeneration. It is suggested that some property of the surface of sperm heads may render them particularly susceptible to phagocytosis. Phagocytosis of spermatozoa may not have long-term harmful effects for the epithelium since these epithelial cells presumably have a high rate of turnover.

Animals↗
PubMed1977

Differentiation of catalases in Mycobacterium phlei on the basis of susceptibility to isoniazid: association with peroxidase and acquired resistance to isoniazid.

Mycobacterium phlei contains two catalase activities and a single peroxidase activity. The latter is associated with one of the catalases. The single catalase-peroxidase enzyme accounted for 75% of the total catalase activity and was lost upon acquisition of resistance to the antitubercular drug isoniazid (INH). Heat-treated (68 degrees C) wild-type cells showed similar decreases in catalase activity as well as complete loss of peroxidase activity. Catalase activity in the INH-resistant strain of M. phlei (Inh(r)) was unaffected by heating. The heat-sensitive catalase of the wild-type M. phlei was completely inhibited by 0.1 M INH, and Cu(2+) enhanced this inhibitory effect by 100-fold. No inhibition of activity was found with the heat-stable enzyme. Equivalent inhibition of catalase was also observed with nicotinic acid hydrazide and benzoic acid hydrazide. Peroxidase activity was also completely inhibited by any one of the three hydrazides, either INH, benzoic acid hydrazide, or nicotinic acid hydrazide at 10(-3) M. The presence of two catalase activities and the loss of one (catalase-peroxidase) on acquiring INH resistance or heating wild-type cells was confirmed by acrylamide gel electrophoresis of the cell-free extracts.

Bacterial Proteins↗
PubMed1975

Cell surface structure of rodent sperm heads.

Replicas of critical point dried rodent sperm were examined by transmission electron microscopy. The surface of rat sperm heads appeared to be coated with regularly spaced 90A lamellar material. The plasma membrane overlying the acrosomal region of guinea pig spermatozoa displayed a regular scalloped array of lamellar structures. In replicas, the surface of Chinese hamster spermatozoa appeared coated by an array of small tubles and vesicles in the region overlaying the acrosome. It was possible to obtain replicas of the outer acrosomal membrane by removing the plasma membrane of mouse spermatozoa by brief treatment with Hank's balanced salt solution containing 0.2-0.5% MgC12. Replicas of the surface of the outer acrosomal membrane reveal evenly spaced, hexagonally-packed 90A particles similar to those which have been observed by other workers in replicas of freeze fractured outer acrosomal membranes. The finding of hexagonally arranged structures on the surface of the outer acrosomal membrane which appear very similar to those which have been observed in the plane of the membrane suggests that protein molecules in the plane of the membrane may protrude through or in some other manner distort the membrane surface. The post-acrosomal region of mouse sperm displays parallel lamellae with 100A spacing. If surface changes occur on sperm heads during maturation or capacitation, it should be possible to detect them with this technique.

Animals↗
PubMed1973

Repopulation of postmitotic nucleoli by preformed RNA. II. Ultrastructure.

The reconstruction of the nucleolus after mitosis was analyzed by electron microscopy in cultured mammalian (L929) cells in which nucleolar RNA synthesis was inhibited for a 3 h period either after or before mitosis. When synchronized mitotic cells were plated into a concentration of actinomycin D sufficient to block nucleolar RNA synthesis preferentially, nucleoli were formed at telophase as usual. 3 h after mitosis, these nucleoli had fibrillar and particulate components and possessed the segregated appearance characteristic of nucleoli of actinomycin D-treated cells. Cells in which actinomycin D was present for the last 3 h preceding mitosis did not form nucleoli by 3 h after mitosis though small fibrillar prenucleolar bodies were detectable at this time. These bodies subsequently grew in size and eventually acquired a particulate component. It took about a full cell cycle before nucleoli of these cells were completely normal in appearance. Thus, nucleolar RNA synthesis after mitosis is not necessary for organization of nucleoli after mitosis. However, inhibition of nucleolar RNA synthesis before mitosis renders the cell incapable of forming nucleoli immediately after mitosis. If cells are permitted to resume RNA synthesis after mitosis, they eventually regain nucleoli of normal morphology.

Cell Nucleolus↗