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Biomedical subjects

M Hassan

Publications and source records attributed to M Hassan.

At least 199 records · Page 11Linked to original sources
PubMed1987

Non-separation radioassay for cortisol binding capacity in human serum.

A radioassay for the measurement of cortisol binding capacity in human serum was developed and the results validated by radioimmunoassay of serum corticosteroid binding globulin. The mini-scale method is simple, reliable and rapid, and avoids separation of partitioned phases. The linear correlation between the free cortisol index and free cortisol concentration as calculated by the two methods utilizing serum samples with normal and abnormal protein concentrations was r = 0.962 (n = 114, p less than 0.001) and the regression equation was y = 3.516 x - 2.632. The technique requires no preparation of reagents, and the assay can be performed in 45 minutes using 0.05 ml of serum or plasma.

Circadian Rhythm↗
PubMed1987

Leiomyosarcoma of the inferior vena cava. Ultrasonographic appearance.

Ultrasonographic features of six leiomyosarcomas of the inferior vena cava are described. In most cases, the presentation is typical enough to strongly suggest the histologic diagnosis. The tumor is usually greater than 10 cm long, hypoechoic, heterogeneous. Cystic components can be found. It is sharply demarcated from neighboring organs which are displaced. The mass is located at the very place of the inferior vena cava, the lumen of which is no longer seen. It is fusiform shaped, surprisingly sparing the aorta. Differential diagnosis along with other radiologic examinations, pathologic findings, and prognosis are discussed.

Adult↗
PubMed1987

[Ultrasonic pseudotumoral aspect of cirrhosis].

Seven cases of cirrhosis with non-tumoral nodules on ultrasound imaging are reviewed. Comparison of ultrasound and histopathologic data provided information on mode of formation and pathologic significance of these images. They correspond usually to a particular distribution of fibrosis and steatosis, exceptionally to regenerating nodules. Nodule formations seen on ultrasound images are independent of histopathologic criteria defining micro- and macro-nodular cirrhosis. Ultrasound guided cytohistology is the only examination allowing their distinction from true tumoral lesions.

Diagnosis, Differential↗
PubMed1987

Distribution of thyroid diseases and evaluation of laboratory parameters used in their diagnosis.

A retrospective rationalization of commonly performed tests and procedures for the assessment of patients with suspected thyroid disease was attempted. The final diagnosis, in 392 consecutive new referrals to a central thyroid clinic, was primarily established by combined criteria of clinical/scintigraphic/cytopathologic findings. Detailed statistical analysis and evaluation of the accumulated data have demonstrated that: (a) only 15.8% of patients exhibited measurable thyrometabolic disturbances, thus indicating a rather limited scope for the application of laboratory tests in screening for thyroid diseases; (b) the measurement of serum total thyroxine with the thyroid hormone uptake test and the derivation of the free thyroxine index constitute, at present, the most appropriate initial in vitro laboratory procedure for assessing thyrometabolic function; and (c) recently available innovative methods for estimating serum levels of free thyroid hormones have no advantages over established assays.

False Negative Reactions↗
PubMed1986

Computer simulations of cyclic enkephalin analogues.

Molecular dynamics simulations and energy minimization studies of cyclic enkephalin analogues incorporating retro-inverso modifications have been carried out. The dynamic trajectories are analyzed in terms of the relative mobility of the 14-membered rings, conformational transitions among equilibrium states, and hydrogen-bonding patterns. The cyclization of the molecules reduces the motion of the ring structures substantially. Time-correlated conformational transitions resulting in the reorientation of peptide units are observed. Hydrogen bonds form principally C7 structures. Because of the incorporation of retro-inverso residues, C6 and C8 structures are also formed. Starting conformations for energy minimizations were obtained from the molecular dynamics simulations and from a systematic search of the conformational space available to the molecules. Several minimum energy backbone and side-chain conformations were found for each analogue. The effect of retro-inverso residues on hydrogen-bonding patterns and backbone conformations is discussed.

Amino Acid Sequence↗
PubMed1986

Ventricular tachycardia associated with non-freon aerosol propellants.

A previously well 2-year-old child presented with seizures and ventricular tachycardia shortly after playing with an aerosol can of a well-known proprietary deodorant. She required intensive care and survived without sequelae. The propellants used in this product were isobutane, n-butane, and propane. The propellants have been thought to be safer than the previously used Freons, which were known to be cardiotoxic and neurotoxic. Significant exposure was confirmed by the detection of n-butane and isobutane in the patient's serum. We conclude that unintentional exposure to non-Freon aerosol propellants in a nonconfined space can be hazardous to children. Aerosol cans should be considered to represent toxic hazards and should be kept out of reach of children.

Acetone↗
PubMed1986

Antenatal phenobarbital for the prevention of neonatal intracerebral hemorrhage.

Forty-six pregnant women less than 35 weeks of gestation were enrolled in a prospective randomized controlled study evaluating the effects of antenatal phenobarbital on neonatal intracerebral hemorrhage. The women were randomly assigned to control (n = 22) or treatment (n = 24) groups; the treatment group received 500 mg of phenobarbital intravenously. The time interval between the dose of phenobarbital and delivery was 5.5 +/- 4.8 hours (mean +/- SD). The infants in the control group (n = 23) and those in the phenobarbital-treated group (n = 25) were comparable regarding birth weight, gestational age, and other obstetric and neonatal risk factors associated with intracerebral hemorrhage. The incidence of intracerebral hemorrhage was 56.5% (13 of 23 infants) in the control group and 32% (eight of 25 infants) in the phenobarbital-treated group (p = 0.08). Moderate or severe hemorrhage was diagnosed in six of 13 control infants and in none of the phenobarbital-treated infants (p less than 0.01). The mortality rate was significantly lower in the phenobarbital-treated group (two of 25 infants) than in the control group (eight of 23 infants; p less than 0.05). Our study suggests that antenatal phenobarbital administration results in a decrease in mortality and in the severity of intracerebral hemorrhage in the preterm neonate.

Cerebral Hemorrhage↗
PubMed1986

The effect of vaginal administration of low-dose oral contraceptive tablets on human ovulation.

The effect of vaginal administration of a low dose combined oral contraceptive pill containing 0.15 mg levonorgestrel and 0.03 mg ethinyl oestradiol was studied in twenty women for a total of 58 cycles. Ovulation was suppressed in all treatment cycles in women receiving two pills daily. Failure of suppression of ovulation occurred in four out of 26 treatment cycles in women receiving one pill daily. Only seven women complained of side effects; most of the side effects were mild and disappeared gradually within the first treatment cycle. Intermenstrual spotting was present in only one case receiving one pill daily. It is concluded that vaginal administration of low dose combined pills has a good ovulation suppression effect with minimal side effects and with good cycle control.

Administration, Topical↗
PubMed1986

Degradation of busulfan in aqueous solution.

The influence of pH, phosphate buffer components and temperature on the degradation rate of busulfan was studied. The analysis was performed using gas chromatography with electron capture detection and reversed-phase liquid chromatography with radioactivity monitoring. The degradation rate of busulfan showed no pH dependence in the range pH 1.5-11 and increased at higher pH values. The degradation rate constant was 0.034 +/- 0.001 h(-1) (S.E.M.) for the degradation of busulfan in pure water and 0.45 +/- 0.01 h(-1)M(-1) (S.E.M.) for the reaction of busulfan with the hydroxide ion at 37 degrees C. The reactivity of HPO(4)(-2) was six times higher than the reactivity of H(2)PO(4)(-1) towards busulfan. The hydrolysis products were identified as tetrahydrofuran and methanesulphonic acid by nuclear magnetic resonance spectroscopy.

Journal Article↗
PubMed1986

Pirenzepine and propantheline effects on esophageal pressure responses to bethanechol.

Pirenzepine is an antisecretory anticholinergic type drug that has recently been shown to be relatively free of usual anticholinergic side effects on esophageal smooth muscle. It has also been suggested that this drug might release some of the inhibitory control of the esophagus and allow increased muscle contractions. To test this hypothesis, we compared the response of the lower esophageal sphincter (LES) and esophageal peristaltic contractions to bethanechol in 12 healthy controls after background oral doses of placebo, pirenzepine (50 mg), and propantheline (30 mg). After baseline placebo, bethanechol (40 micrograms/kg subcutaneously) produced the expected significant increases in LES pressure and amplitude of peristaltic contractions. Maximal increases were 51.9 +/- 14.9 and 29.5 +/- 7.0%, respectively. Also as expected, propantheline inhibited the cholinergic stimulation from bethanechol, allowing only a 10.1 +/- 13.6% increase in LES pressure and a decrease in peristaltic contraction amplitudes (-44.1 +/- 5.0%) after bethanechol. After background pirenzepine, the responses to bethanechol were intermediate between the other two drugs. A significant increase (44.2 +/- 16.4%) in LES pressure occurred after bethanechol while no significant changes (6.9 +/- 5.8%) were noted in peristaltic amplitudes with this drug. Typical side effects of dry mouth were noted in six of the 12 subjects with propantheline and in only three subjects after pirenzepine. These studies once again confirm the absence of usual anticholinergic side effects with oral pirenzepine compared to oral propantheline in the doses studied. We could find no evidence for a release of cholinergic inhibition after pirenzepine administration.

Adult↗
PubMed1986

[Codus: a coding system for ultrasonic examinations].

A semeiologic and anatomic code for ultrasound imaging data has been in use for 3 years. A simple index, it allows coding under specific headings of almost all ultrasound record sheets and can be modified as a function of the requirement of different departments. It is also perfectly well adapted for inclusion in a data-processing system.

Abstracting and Indexing↗
PubMed1986

[Hepatic pseudo-nodule of diaphragmatic origin. Apropos of 6 cases].

Ultrasound images in 6 patients with hyperechogenic "pseudo-nodules" of diaphragmatic origin were analyzed. In each case the findings corresponded to variations in curve of right diaphragmatic dome on radiology, but these diaphragmatic bumps were not associated routinely by a pseudo-nodule. A semiologic explanation for the formation of the ultrasound image is suggested.

Diagnosis, Differential↗
PubMed1986

Therapeutic drug levels and toxicology screen.

Toxicologic analysis cannot supplant physician skills in the diagnosis and management of poisoning; however, it is a useful adjunct when properly used. Laboratory use should reflect critical consideration of clinical contribution as well as insight into institutional capability. A detailed historic review and interview of multiple sources may provide more useful and expeditious information than the blind "drug screen." Test ordering should be limited to that which directly contributes to clinical patient management.16 Similarly, test results must be interpreted in the clinical context of patient presentation. The reported units of measurement must be carefully scrutinized; and the potential for laboratory error must be appreciated. Most importantly, communication and cooperation must be maintained between the physician and laboratory personnel if the resource is to be optimally used.

Chromatography, Thin Layer↗
PubMed1985

The effects of chronic bromocriptine treatment on behaviour and dopamine receptor binding in the rat striatum.

Agonist-induced rotation and striatal binding of [3H]spiperone ([3H]SPIP) were assessed in rats with unilateral lesions of the substantia nigra during and after a period of chronic bromocriptine administration. Agonist-induced rotation significantly increased over a three week period of daily administration of bromocriptine (10 mg/kg i.p.); control animals were tested for agonist-induced rotation at one week intervals, which remained constant. Rotation was increased by chronic bromocriptine administration in response to either of two DA agonists, apomorphine (APO) and bromocriptine, suggesting that increased agonist sensitivity did not reflect a reduction in the metabolism of bromocriptine. Striatal binding of the dopamine D2 radioligand, [3H]SPIP, was significantly increased in the denervated striata of nigra-lesioned rats. Chronic bromocriptine administration decreased binding in denervated striata to levels not significantly different from control values. [3H]SPIP binding in intact striata was significantly reduced by bromocriptine to below control values. Differences in receptor levels reflected changes in the maximum density of binding sites with no change in affinities. Paradoxical behavioural hypersensitivity developing during chronic bromocriptine levels is not apparently mediated by changes in striatal D2 binding sites.

Animals↗