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Biomedical subjects

R M Klein

Publications and source records attributed to R M Klein.

214 records · Page 12Linked to original sources
PubMedDate not supplied

Models for the study of cell proliferation in the developing gastrointestinal tract.

Which is the best system to study in order to obtain data for the human developmental situation? While the temporal pattern of differentiation and growth in some of these species is similar to human development, there are major differences in terms of absorption of immunoglobulins. Humans and rabbits receive virtually complete passive immunity in utero, while rats receive partial immunity, and other species such as the calf, sheep, and pig receive virtually their complete passive immunity during the postnatal period. The morphological similarity of the neonatal rat and mouse small intestine to human fetal small intestine between 10 and 22 weeks adds some validity to the limited use of this model. However, the pattern of gastrointestinal differentiation late in gestation; the dependence on the postnatal period for the transfer of passive immunity; and the delayed closure of the gut are limiting factors in the use of this model comparison to the human situation. Although the opossum provides a useful model for the study of gastrointestinal development in a species with an extremely dependent, underdeveloped newborn and an extremely delayed closure of the gut, this situation is not analagous to the human fetal and neonatal pattern of gastrointestinal development. While animals such as the calf, pig, and sheep are morphologically similar to the human condition and exhibit a relatively short postnatal period of functional immunoglobulin uptake they are almost completely dependent upon the early postnatal period for transfer of passive immunity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Hemorrhage of major branch retinal artery during vitrectomy.

A 45-year-old man had vitreoretinal surgery for intraocular foreign body. Five weeks postoperatively he developed severe proliferation of fibrous tissue from a chorioretinal scar at the site where the intraocular foreign body had lacerated the inferior temporal retinal artery. During a second vitreous surgical procedure, there was severe hemorrhaging from the previously lacerated inferior temporal retinal artery. Elevation of the intraocular pressure to 80 mm Hg after complete air fluid exchange, followed by repeated application of diathermy, resulted in permanent closure of the inferior temporal retinal artery. Elevation of intraocular pressure above the systolic blood pressure of the retinal artery following air fluid exchange offers a successful method for dealing with this serious complication of vitreoretinal surgery.

Eye Foreign Bodies↗
PubMedDate not supplied

Isoproterenol-induced changes in cell cycle kinetics of parotid gland acinar cells in 8-day-old rats.

Isoproterenol (IPR) was shown to alter some parameters of the parotid gland acinar cell cycle in 8-year-old rats. Although the deoxyribonucleic acid (DNA) synthetic period (S) was decreased and the pre-DNA synthetic (G1) period was lengthened, there were no differences in the total cycle time. There was an increase in the 3H-thymidine labeling index from 35.7 to 50.8% combined with a decrease in the value of the mitotic index from 2.64 to 2.16% after IPR was administered. The results suggest that noncycling (G0) cells may be involved in the normal differentiation of the parotid gland and that IPR alters the transition of acinar cells between the cycling and noncycling state.

Animals↗