Biomedical subjects
Publications and source records attributed to M Osman.
Separation of the enamel organ and pulp of mice tooth germs by trypsin removed the basal lamina. Within 18 hours in cultivated reassociations of enamel organ and pulp, a new lamina was deposited. When the epithelial component was cultivated alone, no basal lamina formed.
The restoration of the basement membrane and the terminal differentiation of odontoblasts were studied in iso- and heterochronal reassociations between dental mesenchyme and enamel organs. It was suggested that the cytodifferentiation of odontoblasts was triggered by the basement membrane secreted by the enamel organ of a specific stage.
Sixteen or eighteen day old mouse embryonic first lower molars were treated with 5-bromodeoxyuridine (BrdU) in vitro. --In 16-day old tooth germs cytodifferentiation of both odontoblasts and ameloblasts was inhibited. This inhibition was reversible. --In 18-day old tooth germs, the odontoblasts localized at the top of the principal cusps (post-mitotic cells) differentiated normally and secreted predentin. In these conditions ameloblasts localized in front of functional odontoblasts differentiated, although they were able to incorporate BrdU. --In others experiments, control and BrdU-treated tooth germs were dissociated into enamel organs and pulps. Cultivated associations between either control or BrdU treated pulps with either control or BrdU treated enamel organs were analyzed. It appeared that the primary effect of BrdU might result in its incorporation in the preameloblasts which were no longer able to interact normally with the preodontoblasts.
The first lower molar tooth germs removed from 16-day-old mouse embryos were cultured for 2 days on a standard medium and then for 24 hours on the same medium containing BrdU (treated tooth germs) or not (controls). We attempted to study the effects of 5-Bromodeoxyuridine on the type I and type III collagen synthesis 24 (stage 16 + 4) and 72 (stage 16 + 6) hours after the incorporation of this thymidine analogue. At stage 16 + 4, type I and type III collagen were synthesized both in control and BrdU-treated tooth germs. However BrdU induced quantitative modifications in the type I collagen synthesis which might be explained by modifications in the turnover of this type of collagen. At stage 16 + 6, the BrdU treatment resulted in the inhibition of the terminal differentiation of odontoblasts. Consequently, the normal amplification of collagen type I synthesis could not occur. However, both control and BrdU-treated tooth germs synthesized type I and type III collagen. Quantitatively, the synthesis of type III collagen was slightly affected by BrdU treatment.
The action spectrum of photoinduction of carotenoid biosynthesis in Verticillium agaricinum has a high peak in the near-UV region with very small peaks in the blue, yellow and red regions. This suggests that neither a flavoprotein nor a carotenoid could be the photoreceptor, but a new unknown pigment system. Sporulation however is not photoregulated and is unaffected by light in the near-UV region. So, mycochrome cannot be implicated in the sporulation of this fungus. Further, sporulation and carotenogenesis must be under separate regulatory control in this organism, but not necessarily so in other organisms.
Carotenoids identified in Verticillium agaricinum under near-UV were beta-, zeta-, and gamma-carotenes, neurosporene, torulene, neurosporaxanthin and one of its esters. Evidence supports the proposal that gamma-carotene, and not torulene, is the immediate precursor of neurosporaxanthin. It is also suggested that phytochrome may be involved in the high irradiance reactions (HIR) causing carotenoid synthesis in this fungus although there is no knowledge of how this is effected. Spores grown under near-UV conditions varied in size and shape from those grown in the dark. A new pigment (390, 420 nm) is also proposed as the photoreceptor for carotenogenesis in V. agaricinum.
The effect of prostaglandin F2alpha (PGF2alpha) on the nonpregnant human uterus was evaluated in 35 patients. The compound was administered both by intra-uterine and intravenous routes. Two groups of volunteers were studied;fifteen cases who were under oral contraceptives and twenty women with normal ovulatory cycles. The uterus under the influence of oral contraceptives showed a reduced response to local and systemic administration of PGF2alpha at all phases of the menstrual cycle. The implications of these findings in certain physiological and pathological conditions related to reproduction are discussed.
The clinical entity of functional infertility still remains unexplained and largely lacking a line of proper management. The uterine response to prostaglandin E2 (PGE2) and prostaglandin F2alpha (administered by intravenous and intrauterine routes) was evaluated during different phases of the menstrual cycle in five functionally infertile women. The results (quantitative and qualitative) were compared with those elicited among 20 fertile women. There were no apparent differences between the two groups with respect to either compound (systemic or local) when given during the proliferative or luteal phase of the cycle. However, at midcycle, about the time of ovulation (days 13 to 18), there was a salient deviation in the type of response following local instillation of PGE2; in the normal fertile group there was a definite inhibition of motility, while uteri in the functionally infertile group showed marked stimulation. The possible role of this aberrant uterine response in the etiology of functional infertility is discussed.
The in vitro evolution of interspecific associations between pulps and enamel organs of embryonic Mouse and Rabbit tooth germs was studied. It was shown that young pulps controlled the three-dimensional structure of tooth germs. It was also shown that dental papillae cells and dental epithelial cells, after monolayer culture, did not loose their respective ability to direct the histogenesis of teeth.
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Experiments were conducted to determine the relative effectiveness of selenium (Se) from sodium selenite, selenomethionine and selenocystine for promoting weight gain and preventing exudative diathesis. The chicks used were hatched from eggs low in Se. They were fed a basal diet made up mostly of corn (low in Se) and torula yeast or the basal diet supplemented with various levels of Se from sodium selenite, selenomethionine, or selenocystine. At 10 mug. of added Se per kg of diet, sodium selenite and selenocystine were about equal in promoting weight gain and preventing exudative diathesis. Selenomethionine was less effective. Tissues from chicks fed the various Se sources providing 60 mug. Se per kg of diet for four weeks were analyzed for Se. The content of tissues from chicks fed sodium selenite or selenocystine was similar. Chicks fed selenomethionine had a higher concentration of Se in the pancreas and breast muscle than chicks fed the other two Se sources, but a lower concentration in the kidney, liver, and heart. The level of Se in the kidney, liver, or heart which a Se source produces seems to be more important for preventing exudative diathesis than that which is found in the pancreas or muscle.
The response of the non-pregnant human uterus to intravenous (i.v.) injections and intra-uterine instillation of various doses of prostaglandin E-2 (PGE-2) was evaluated at the different phases of the menstrual cycle in 13 fertile regularly menstruating women who were neither lactating nor using any hormonal therapy. Uterine contractility was recorded by the microballoon technique in at least three sessions(proliferative, mid-cycle and secretory) in a single cycle with endometrial biopsy performed immediately following the last session to ascertain that the particular cycle was an ovulatory one. Single i.v. injections of PGE-I had a consistent stimulatory effect on the contractility throughout the cycle with a tendency towards a decreased uterine response at mid-cycle and luteal phase as compared to the proliferative part of the cycle. Intra-uterine instillation of the compound induced a peculiar and interesting type of response. In the proliferative and secretory phases of the cycle the response was one of stimulation; being more pronounced in the former period. However, around ovulation time, the local administration induced an evident uterine relaxation in most cases without any instance of stimulation. The possible implication of this triphasic response behaviour on the non-pregnant uterus within certain physiological events and pathological conditions is discussed.
Practical diets containing various selenium levels, with and without selenite supplementation, were fed to hens. Eggs were then collected over a 14-day period to determine how quickly changes in dietary selenium affected egg white and yolk selenium. Changes in egg white selenium content were rapid and essentially completed seven days after changing the selenium content of a practical diet. Changes in egg yolk were not yet completed by 14 days. When selenium from practical feedstuffs was fed, the selenium content of dried egg white was about equal to or greater than the selenium content of dried egg yolk. When selenite was fed, the selenium content of dried yolk was higher. Feeding selenomethionine resulted in more selenium in egg white than in egg yolk. Feeding selenocystine resulted in more selenium in egg yolk than egg white, a pattern similar to that from feeding selenite. The data suggest that selenocystine is not incorporated into protein but is metabolized to an inorganic selenium compound.
The effects of Depoprovera and Deladroxone were studied in humans, on certain milk components as well as on the growth of the nursed infants. Both drugs caused reduction in milk yield. Both drugs caused an increase in the concentration of milk total proteins, however. Depoprovera caused an increase while Deladroxone caused a decrease in the total amount of milk proteins per feed. Depoprovera showed no effect while Deladroxone caused an increase in the concentration of milk lipids; however, both drugs caused reduction in the total amount of milk lipids per feed. Both drugs showed no effect on the concentration of milk lactose, but caused reduction in the total amount of milk lactose per feed. The percentage increase in weight of nursed infants was decreased by Depoprovera, but not affected by Deladroxone.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.