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Biomedical subjects

F H Osman

Publications and source records attributed to F H Osman.

10 recordsLinked to original sources
PubMed1989

Acute toxicity and anti acetylcholinesterase potential of some biphenyl derivatives to non target species.

Five newly synthesised biphenyl derivatives were evaluated for their acute contact toxicity (LC50) against rice weevil and honey bee and anti acetylcholinesterase potential (I50) against honey bee, fish, pigeon and rat. Amongst, O,O-dimethyl-O, p-Nitro-biphenyl phosphate was most potent against rice weevil, whereas p-(4-Nitrophenyl) phenyl-N-methyl carbamate against honey bee. Based on I50 values the biphenyl derivatives of phosphoric acid esters were more potent anti acetylcholinesterase (AChE) agents against rat and fish brain AChE while derivative of carbamic esters towards pigeon brain AChE. The anti AChE potency of both groups appear to be of the same order towards bee head AChE.

Animals↗
PubMed1984

A study of interaction between levonorgestrel and ethanol.

Female Wistar rats were pair-fed a diet containing either ethanol (5%) or isocaloric carbohydrate substituent. After 6 weeks, a single dose (5 micrograms/kg) of levonorgestrel was given to the animals in each group either orally, subcutaneously or intravenously. Plasma levels of levonorgestrel at different time intervals were measured by RIA. Chronic alcohol administration did not affect plasma levels of levonorgestrel after oral administration. When the drug was given subcutaneously, plasma levels and AUC were significantly decreased in the alcoholic compared to control group. Following intravenous administration, the elimination half-life of levonorgestrel was shorter while the metabolic clearance was higher in the alcohol-treated group rather than the control group.

Animals↗
PubMed1983

Influence of acetaminophen-induced hepatic necrosis on the pharmacokinetics of levonorgestrel.

The pharmacokinetics of levonorgestrel in control mice and in mice with induced hepatic necrosis were investigated. Hepatic necrosis was induced by fasting mice for 18 hr and then giving the acetaminophen in a dose of 750 mg/kg i.p. Measurement by radioimmunoassay of plasma levonorgestrel has been used to compare the pharmacokinetic parameters of the drug after oral and intravenous administration in both control and liver-affected animals. The pharmacokinetic parameters of levonorgestrel in control mice showed some similarity to those observed in human subjects, save the systemic bioavailability which was about 67% in mice compared to 100% in humans. The animals with induced hepatic necrosis compared with controls showed: 1 - Similar mean plasma levels; 2 - Increased metabolic clearance; 3 - Shortened elimination half-life; and 4 - No change in volume of distribution, half-life of distribution and systemic bioavailability. The reasons for any change have been discussed and interpreted.

Acetaminophen↗
PubMed1976

Potentiation by lithium and protection by rubidium of digitalis intoxication.

Investigating the effects of Li and Rb on the toxicity of digoxin and ouabain revealed Li to be a potentiator while Rb to be a protector. The effects of Rb in this respect are, more or less, qualitatively comparable to those of K; the intensity of Rb effects is more than that of K. In case of digoxin the effect produced from the combined use of both Rb and K is more than each individual effect. With ouabain, however, whereas Rb offered protection K failed to do so. Electrolyte changes in cardiac tissue showed that Li increased the tissue content of Ca while Rb produced the opposite effect. In comparing Rb with K, both increased the K level in the cardiac muscle. However, in the case of ouabain the infusion of K failed to decrease the Ca level and this might explain its failure to protect against ouabain toxicity. This points to the importance of Ca, rather than K, in controlling the excitability of the cardiac muscle and in effecting the toxicity of cardiac glycosides. Evidences presented indicate the superiority of Rb over K and propose its trial in clinical practice.

Animals↗
PubMed1975

5-hydroxytryptamine receptors in uterine smooth muscle.

When studying some of the properties of 5-hydroxytryptamine (5HT) receptors in the rat uterine muscle using phenoxybenzamine (PBZ) as an antagonist it was found that the specific receptors for 5HT in the smooth muscle were selectively blocked by PBZ; a period of 20-minute exposure to the antagonist was required for maximal effect. The blockade produced was of long duration and the recovery of response was relatively slow; it was incomplete throughout the 4-hour observation period. A concentration of 1 X 10(-8) g/ml PBZ produced a parallel shift of the dose-response effects while higher concentrations reduced both the slope and maximal response. The reasons for such a shift were discussed. 5HT produced a rapid onset and offset of effect suggesting that the site of 5HT receptor is on the surface of the cell membrane. Moreover, 5HT could protect its own receptor against PBZ blockade.

Acetylcholine↗