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Biomedical subjects

M Rizk

Publications and source records attributed to M Rizk.

At least 73 records · Page 4Linked to original sources
PubMed1980

MHPG excretion in depression.

3-Methoxy-4-hydroxyphenylethyleneglycol (MHPG) was measured in 24-hour urine collections obtained from 44 drug-free patients hospitalized for a major depressive disorder, MHPG was significantly lower in a group of three biopolar 1 patients than in a group of unipolar patients. The excretion of MHPG did not significantly differ among patients classified as psychoatic, agitated, or retarded subtypes of depression as compared to patients not assigned to these subtypes.

Adult↗
PubMed1979

Identification and quantitation of phenylethylene glycol in human and rat urine, and its elevation in phenylketonuria.

Phenylethylene glycol has been identified in rat and human urine using gas chromatography/chemical ionization/mass spectrometry. A method was developed for the quantitative analysis in urine of this phenylalanine metabolite and of p-hydroxyphenylethanol, a metabolite of tyrosine, by converting them to the pentafluoropropionyl derivatives and measuring them by selected ion monitoring. In human urine, about 90% of the phenylethylene glycol was present in a conjugated form (releasable by glusulase), but the reverse was true for rat urine, with about 90% being present in the unconjugated form. The excretion of free phenylethylene glycol (expressed as ng/mg creatinine) was 2.7-fold higher in a group of untreated phenylketonuric patients than in the control group, but the phenylketonuric patients excreted abnormally low amounts of 3-methoxy-4-hydroxyphenylethylene glycol. Intraperitoneal injections of L-phenylalanine in rats resulted in a small increase in the excretion of phenylethylene glycol. On the other hand, the injection of phenylethanolamine resulted in an 82-fold increase in the excretion of phenylethylene glycol, but phenylethylamine had no effect. These results indicate that the conversion of phenylethylamine to phenylethanolamine is the rate limiting step in this metabolic pathway.

2-Hydroxyphenethylamine↗
PubMed1979

Studies on the effects of ethinyl estradiol and norethisterone acetate on the adrenal cortex and some other tissues in the rat.

Alkaline phosphatase activity (AP) of the adrenal cortex of rats were determined under the effect of ethinyl estradiol (EE) and/or norethisterone acetate (NA), the two components of the contraceptive pill gyn-anovlar (Schering AG Berlin). A pathological study was also carried out to examine the effects of EE and NA on other tissues mainly the liver, lungs, spleen and ovaries. EE in a dose of 10 micrograms/day for 2 weeks caused a significant increase in the weight of the adrenal but no significant increase in the AP/g cortical tissue. The 25 and 50 micrograms doses for the same period caused a significant increase in both adrenal weight and AP. When treatment was prolonged to 6 weeks no effect on adrenal weight or AP was detected. The same finding was obtained with NA in a dose of 7 mg/rat/day for 2 weeks. The 14 mg dose of NA for the same period caused a significant increase in adrenal weight but no effect on AP. The 21 mg dose caused a significant increase in adrenal weight accompanied by significant decrease in AP/g cortical tissue. Treatment with NA for 6 weeks caused a rise in adrenal weight and AP with the 7 mg dose, then a decline in AP with the 14 mg dose, and a decline in both adrenal weight and AP with the 21 mg dose. As regards the effects of EE and NA on other tissues, EE was found to have a powerful stimulatory effect on the reticuloendothelial system (RES) as well as toxic effects on the liver. NA did not produce such lesions except for the large doses and prolonged periods of treatment. In addition NA produced cholestasis in the liver associated with staining of the liver cells with bile. Combination of EE and NA in the form of gyn-anovlar produced more powerful stimulation of RES and decreased the toxic manifestations of either component. As regards the ovaries, administration of 50 micrograms EE for 6 weeks produced profound hyperplasia of the granulosa cells of the Graafian follicles and inhibited ovulation, however, NA did not inhibit ovulation. With gyn-anovlar, the effect of EE on the ovaries seemed to predominate and ovulation was inhibited.

Adrenal Cortex↗
PubMed1979

Evaluation of certain pharmaceuticals with dibromodimethylhydantoin. Part 2: Determination of analgesics.

1,3-Dibromodimethylhydantoin (DBH) is a stable dihalogen reagent. It can be used as an analytical reagent for certain analgesics. It gives stoichiometric results by direct titration in acid medium. The end point is detected visually or potentiometrically. Also spectrophotometric titrations have been attempted at 345 nm. In all cases the results of the analysis of the drugs studied either in the pure state or in their dosage forms comply with those given by N-bromo succinimide (NBS) and by the official methods, however this application is distinguished by simplicity and accuracy.

Analgesics↗
PubMed1978

Gas-liquid chromatographic analysis of lynestrenol in contraceptive tablets.

A simple procedure for the estimation of lynestrenol in contraceptive tablets is described. The method consists of extraction of the hormone into dichloromethane followed by g.l.c. of the resulting solution. 3 alpha-Etiocholanol-17-one is demonstrated as a suitable internal reference standard.

Chromatography, Gas↗
PubMed1975

Histochemical measurements of rat kidney hexokinase.

HK has been measured in substructures of the developing rat nephron. Reactions were carried on samples dissected from freeze dried kidney and assayed in 1 mul reaction volume utilizing the "oil-well" technique. Samples from 4 days prenatal to 44-day adult were analyzed. Activity during development decreased in G, PCT, and it increased in ALH. There was little change in PRT, DCT and CT. Activity in small arteries decreased.

Adenosine Triphosphate↗
PubMedDate not supplied

Fluorimetric determination of oxamniquine in biological fluids.

A highly sensitive and specific fluorimetric method was developed for the determination of oxamniquine in biological fluids (urine and plasma). The proposed method is based on the reduction of oxamniquine using zinc/calcium chloride to obtain its nitroso derivative. The latter is then allowed to react with 2-cyanoacetamide to get a highly fluorescent product. The different experimental parameters affecting the intensity of the fluorescence were carefully studied and incorporated into the procedure. Under the described conditions, the method is applicable over the concentration range of 0.08-0.88 microgram/ml with a minimum detectability (S/N = 2) of 8 ng/ml. The percentage recoveries from spiked urine and plasma were 99.75 +/- 1.58 and 97.46 +/- 0.44%, respectively.

Calibration↗
PubMedDate not supplied

Derivative spectrophotometric analysis of 4-quinolone antibacterials in formulations and spiked biological fluids by their Cu(II) complexes.

A derivative UV-spectrophotometric analytical procedure was developed for determination of three 4-quinolone antibacterials: norfloxacin (NFX), ciprofloxacin (CFX), and sparfloxacin (SFX). The method depends on the complexation of Cu(II) with the studied compounds in aqueous medium. A third order, measurement was applied for their quantification. A linear correlation was established between the amplitude of the peak and concentration for all the studied drugs in the range of 15-80, 35-120, and 200-700 ng/mL, with minimum detectability (S/N = 2) of 1.0, 1.3, and 5.1 ng/mL for NFX, CFX, and SFX, respectively. The method was successfully applied for accurate, sensitive, and selective determination of the studied drugs in bulk and tablets formulation with average percentage recoveries of 99.22 +/- 0.55 to 100.33 +/- 1.60. The results obtained were favorably compared with those of the reference method. The method was also used to determine sparfloxacin in spiked human plasma and urine. The results obtained were satisfactory, accurate, and precise.

4-Quinolones↗