SAID SHEHATA

n/a

Sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were once administered in goats via oral and i.v. route (100 mg/kg b.wt.) for determination of plasma and urine concentrations of the unchanged sulphonamides and their acetylated derivatives, kinetic behavior, systemic bioavailability, tissue levels and acetylation. The highest plasma concentrations of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were reached after 0.64, 1.31 and 0.46 hr following oral administration, with an absorption half-life of 0.84, 1.31 and 0.38 hr and an elimination half-life of 3.51, 5.01 and 5.55 hr, respectively. Following a single i.v. injection, the kinetic disposition of sulphamethoxazole and sulphadimethoxine followed a one-compartmental model with an elimination half-life of 1.48 and 1.76 hr and a total body clearance-time curve of sulphadimethyloxazole, after a single i.v. injection, could be described by a two-compartmental open model with an elimination half-life of 3.27 hr, a volume of distribution of 248.07 ml/kg and a total body clearance of 0.82 ml/kg/min. The systemic bioavailability was 19.95, 11.37 and 23.27% after oral administration of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine, respectively. The percentages of serum protein binding of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were determined in most of the body tissues, collected 4 hr after i.v. injection. The highest concentration was found in kidney and liver. On the other hand, sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were N4-acetylated in the body tissues to a higher extent than that in plasma. Acetylation was highest in rumen and skeletal muscle.

The effects of radiation exposure and drug treatment on the immediate type of hypersensitivity reaction were studied. Guinea-pigs were sensitized by s.c. injections of antigen. The animals were killed 3 weeks later and the lungs were perfused through the pulmonary artery. The perfusate was allowed to superfuse a guinea-pig ileum to estimate its total content of mediators. Results revealed that the mere injection of antigen to the perfused lung resulted in the release of spasmogens which caused contraction of the guinea-pig ileum. Analysis of the effluent showed an increase in the amount of PGs (measured biologically) and histamine (measured fluorimetrically) released during challenge. The response of the ileum to the antigen challenge was inhibited by the infusion of diclofenac (20 micrograms.ml-1) or piroxicam (25 micrograms.ml-1). The drugs also inhibited the release of PGs and histamine from the perfused lungs. Exposure of animals to gamma-radiation, before sensitization, caused a reduction in the amount of mediators released during challenge. On the other hand, in nonsensitized animals, a single radiation dose level of 2 Gy caused fluctuation in the amount of PGs and histamine released during challenge throughout the 3 weeks period of the experiment. Diclofenac and piroxicam effectively reduced the amount of mediators released from sensitized perfused lung isolated from both nonirradiated and irradiated animals. This may, at least partly, explain their protective effect against the exaggerated inflammatory response following gamma-irradiation exposure.

The effects of radiation exposure and drug treatment on the immediate type of hypersensitivity reaction were studied. Guinea-pigs were sensitized by s.c. injections of antigen. The animals were killed 3 weeks later and the lungs were perfused through the pulmonary artery. The perfusate was allowed to superfuse a guinea-pig ileum to estimate its total content of mediators. Results revealed that the mere injection of antigen to the perfused lung resulted in the release of spasmogens which caused contraction of the guinea-pig ileum. Analysis of the effluent showed an increase in the amount of PGs (measured biologically) and histamine (measured fluorimetrically) released during challenge. The response of the ileum to the antigen challenge was inhibited by the infusion of diclofenac (20 micrograms.ml-1) or piroxicam (25 micrograms.ml-1). The drugs also inhibited the release of PGs and histamine from the perfused lungs. Exposure of animals to gamma-radiation, before sensitization, caused a reduction in the amount of mediators released during challenge. On the other hand, in nonsensitized animals, a single radiation dose level of 2 Gy caused fluctuation in the amount of PGs and histamine released during challenge throughout the 3 weeks period of the experiment. Diclofenac and piroxicam effectively reduced the amount of mediators released from sensitized perfused lung isolated from both nonirradiated and irradiated animals. This may, at least partly, explain their protective effect against the exaggerated inflammatory response following gamma-irradiation exposure.

The effects of radiation exposure and drug treatment on the immediate type of hypersensitivity reaction were studied. Guinea-pigs were sensitized by s.c. injections of antigen. The animals were killed 3 weeks later and the lungs were perfused through the pulmonary artery. The perfusate was allowed to superfuse a guinea-pig ileum to estimate its total content of mediators. Results revealed that the mere injection of antigen to the perfused lung resulted in the release of spasmogens which caused contraction of the guinea-pig ileum. Analysis of the effluent showed an increase in the amount of PGs (measured biologically) and histamine (measured fluorimetrically) released during challenge. The response of the ileum to the antigen challenge was inhibited by the infusion of diclofenac (20 micrograms.ml-1) or piroxicam (25 micrograms.ml-1). The drugs also inhibited the release of PGs and histamine from the perfused lungs. Exposure of animals to gamma-radiation, before sensitization, caused a reduction in the amount of mediators released during challenge. On the other hand, in nonsensitized animals, a single radiation dose level of 2 Gy caused fluctuation in the amount of PGs and histamine released during challenge throughout the 3 weeks period of the experiment. Diclofenac and piroxicam effectively reduced the amount of mediators released from sensitized perfused lung isolated from both nonirradiated and irradiated animals. This may, at least partly, explain their protective effect against the exaggerated inflammatory response following gamma-irradiation exposure.

Three groups of five clinically healthy buffaloes each were injected intravenously with sulphadiazine, sulphadimidine and sulphamerazine in a dose of 100 mg/kg b. wt. (as a singly initial dose of 40 mg/kg b. wt. an subsequently the plasma level kept constant by a continuous intravenous infusion of a maintenance dose of 20 mg/kg per hour over a period of 3 hours). It was found that, 1) sulphadiazine, sulphadimidine and sulphamerazine increase the plasma glucose levels at 1, 2, 2.5 and 3.5 hours from the start of i.v. infusion. 2) The glucose concentration in urine increased in the buffaloes infused i.v. with sulphadiazine. 3) The glucose level in urine of buffaloes infused i.v. with sulphadimidine and sulphamerazine was slightly increased. 4) The concentrations of sulphadiazine, sulphadimidine and sulphamerazine in plasma reached its highest level, 2.5, 2 and 2.5 hours during the i.v. infusion, respectively, then declined rapidly. 5) The concentrations of sulphadiazine, sulphadimidine and sulphamerazine in urine reached their highest concentrations 3.5 hours after i.v. infusion.

The composition of the microflora, N2‐fixing bacteria particularly, in different soils cultivated with wheat in Egypt was investigated in some samples collected from the fields after applying the agricultural practices recommended for wheat cultivation and just before sowing. The influence of carbon sources, mineral nitrogen and water regimes on potential dinitrogen fixation (acetylene reduction assay) in soils was investigated. The bacterial population densities including‐N2‐fixing organisms were related to a number of environmental factors such as organic matter content. Among diazotrophs, Azotobacter spp. and Azospirillum spp. were encountered in higher densities in comparison with clostridia. Unamended soils showed a lower acetylene‐reducing activity (0.5–61.5 nmoles C2H4 g−1 h−1). Addition of glucose (1% w/w) greatly enhanced such activity being the highest (86.9–2846.5 nmoles C2H4 g−1 h−1) in the clay soil with the highest organic carbon content (1.42%). Glucose amendment had no significant influence on acetylene reduction in the saline soil. N2‐fixation in barley straw‐amended (1%) soils was not much higher than in unamended soils. Concentrations of up to 70 ppm ammonium‐nitrogen depressed N2‐fixation in soils that received barley straw. Acetylene reduction in submerged soil increased after addition of cellulose. Non‐flooded conditions favoured N2‐fixation in the fertile clay soil amended with sucrose. Copyright © 1989 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

The donor–acceptor interaction of acrylonitrile (AN) with indene (In) has been investigated by means of ultraviolet spectroscopy and dielectric polarization measurements. The latter method yielded a value of 0.5 for the association constant of the charge‐transfer‐complex (CTC) and a 4.02 D for its dipole moment. The copolymerization of the two monomers was characterized by a tendency towards alternation when conducted in the bulk. This might be due to the participation of a weak CTC in the process of copolymerization. However, this tendency disappeared in polar solvents such as DMF. Copyright © 1989 John Wiley & Sons, Inc.

The effect of heat treatment on the structural transformation and electrical conductivity σ of the amorphous alloy Ge20Se5Te75 was studied. X-ray diffraction experiments on annealed samples, at temperatures higher than the glass transition temperature, showed the presence of Te and TeGe crystalline phases. On heating the amorphous sample above the glass transition temperature irreversible electrical conductivity changes were observed. The temporal changes in the σ values of the Ge20Se5Te75 samples at various isothermal annealing temperatures were used to determine the transformation ratios from the amorphous to crystalline state. The kinetic parameters were also calculated. The crystallization is a two-dimensional process. A value of 1.02 ± 0.12 eV was obtained for the activation energy of the crystal growth in the temperature range 230-270 °C. © 1989.

The electrical conductivity of γ irradiated and unirradiated finely divided ferrites of composition Fe3O4, CdFe2O4 and CoxZn1-xFe2O4 (0 ≤ x ≤ 1) was studied in a nitrogen atmosphere as a function of temperature. Fe3O4, ZnFe2O4 and CdFe2O4 showed n-type conduction, whereas CoFe2O4 showed p-type conduction. For CoVxZn1-xFe2O4 it was found that the type of conduction varies with the composition of ferrites. The electrical conduction in Fe3O4 and CoxZn1-xFe2O4 (0 ≤ x ≤1) was explained by a hopping mechanism, whereas the conduction in ZnFe2O4 and in CdFe2O4 is interpreted on the basis of the transfer of charge carriers through cation vacancies present on octahedral sites. The effect of γ irradiation on the conductivity, activation energy, charge carriers and the conduction mechanism was discussed. © 1989.

The electrical conductivity of γ-irradiated and unirradiated finely divided ferrites of composition Fe3O4, CdFe2O4 and Cox Fn1-xFe2O4(0 ≤x ≤ 1) was studied in a nitrogen atmosphere as a function of temperature. Fe3O4, ZnFe2O4 and CdFe2O4 showed n-type conduction, whereas CoFe2O4 showed p-type conduction. For CoxZn1-xFe2O4 it was found that the type of conduction varies with the composition of ferrites. The electrical conduction in Fe3O4, and CoxZn1-xFe2O4(0 ≤x ≤ 1) was explained by a hopping mechanism, whereas the conduction in ZnFe2O4 and in CdFe2O4 is interpreted on the basis of the transfer of charge carriers through cation vacancies present on octahedral sites. The effect of γ-irradiation on the conductivity, activation energy, charge carriers and the conduction mechanism is discussed. © 1989 Chapman and Hall Ltd.

The d.c. and a.c. conductivity and the thermoelectric power of the compounds H3N+(CH2)nN+H 3FeCl4, where n = 2, 3, 7 or 10, have been studied over a temperature range of 150-500 K. The conductivity results confirm the presence of more than one structural phase transition for each compound investigated. The thermoelectric power measurements show that electrons are the main charge carriers in all crystal phases. The conductivity results are explained on the basis of an electron-hopping mechanism over the whole temperature range. © 1989.

DTA, dc-conductivity and thermoelectric power of the compounds RMnCl4, RCoCl4 and RMn0.5Co0.5Cl4; {Mathematical expression}, have been measured over a temperature range of 300-500 K. Both DTA and dc-conductivity results showed the presence of many phase transitions in each one of the complexes investigated. The conductivity results were explained in terms of an electron hopping mechanism. The effect of γ-irradiation on the conductivity data and the type of crystal phases have been investigated and discussed. © 1989 Akadémiai Kiadó.