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Biomedical subjects

M Hassan

Publications and source records attributed to M Hassan.

At least 145 records · Page 8Linked to original sources
PubMed1994

Effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal shunts.

The present study was performed to investigate the effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal (VP) shunts. The series included 35 hydrocephalic patients and five individuals without hydrocephalus who were used as controls. The hydrocephalic patients were divided into three groups: 15 patients who received VP shunts with a differential-pressure valve (DP group); 11 who received VP shunts with a variable-resistance valve (VR group), and 13 hydrocephalic patients (Hyd group) who had not received shunts (four underwent VP shunts later). The cerebral blood flow (CBF) of patients in the supine and upright positions was measured by technetium-99m hexamethylpropylenamine oxide (HMPAO) single-photon emission computerized tomography in each patient, using the subtraction technique. Cerebral perfusion pressure (CPP) was taken as the difference between the mean arterial blood pressure and ventricular fluid pressure, both referenced to the level of the foramen of Mono. The patients' heads were elevated stepwise from supine to upright. Percent changes of the mean CBF in the upright position (% delta mCBFupr) were 24.9% +/- 4.3% (mean +/- standard error of the mean) in the DP group, 6.2% +/- 2.7% in the VR group, 3.5% +/- 2.6% in the Hyd group, and 4.5% +/- 2.2% in the control group. Patients in the DP group showed a pathological increase in CPP with head elevation, whereas those in the Hyd and VR groups showed a physiological decrease in CPP. Three patients with differential-pressure valves, whose % delta mCBFupr was markedly high, developed low-intracranial pressure syndrome. In conclusion, shunted patients with a DP valve showed pathological intracranial hemodynamics in the upright position. This pathological hemodynamic stress in patients with long-standing differential-pressure valve implantation may induce pathological changes in the brain such as subependymal gliosis.

Adolescent↗
PubMed1994

Tacrine in Alzheimer's disease: pharmacokinetic and clinical comparison of oral and rectal administration.

In a previous pharmacokinetic study in Alzheimer patients great inter-individual variation and low oral bioavailability of the cholinesterase inhibitor tacrine (tetrahydroaminoacridine, THA) were found. In the present investigation oral and rectal administration of tacrine were compared with the aim to find a route for improved bioavailability through diminished first-pass metabolism in the liver. Eight patients suffering from Alzheimer's dementia were given tacrine by oral (25 and 50 mg b.i.d.) and rectal (12.5 and 25 mg b.i.d.) routes for 1 week with 4-6 weeks washout in between. Drug hydroxylation capacity in the patients was determined using the debrisoquine test. Levels of tacrine in plasma and cerebrospinal fluid (CSF) were determined and the cognitive performance was examined by the Mini-Mental State Examination (MMSE) and the Alzheimer Deficit Assessment Scale (ADAS). Tacrine was well tolerated in all but one patient, a slow hydroxylator, who developed an aplastic anemia. MMSE and ADAS scores did not significantly change, except for word recall which was improved on tacrine when given by the rectal route. Pharmacokinetic analysis of the two administration routes revealed that the drug dose may be reduced by almost 50% when given rectally compared to orally. Concentrations of tacrine in the CSF were significantly lower and correlated linearly with the concentrations in plasma.

Administration, Oral↗
PubMed1994

[Anaphylactic shock and low osmolarity contrast medium].

BACKGROUND: Low osmolality contrast media are generally better tolerated than those with high osmolality. This report describes a case of severe collapse after injecting a low osmolality contrast medium. CASE REPORT: A 15 month-old girl with aortic arch abnormalities was admitted for investigation under general anesthesia. She had a history of allergy but had not previously been exposed to contrast medium. She was given ioxaglate (2 mg/kg) into an artery. The infusion immediately resulted in generalized erythema, tachycardia, hypotensive collapse and ECG abnormalities. The patient was immediately given adrenaline, vasopressive drugs, corticosteroids and plasma protein fraction, which led to a rapid recovery. The ductus arteriosus was ligated a few days later without complications despite the application of iodine to the skin and the use of anesthetic drugs. CONCLUSION: An unpredictable adverse reaction to low osmolality contrast medium can occur. Risk factors must be identified and immediate arrangements made for resuscitation.

Anaphylaxis↗
PubMed1994

[Morphological abnormalities of the pituitary stalk of unknown cause in 4 cases of diabetes insipidus in children].

BACKGROUND: Magnetic resonance imaging (MRI) is the best technique for studying hypothalamic and hypophyseal structures. CASE REPORTS: Four children aged 2 years 5 months to 8 years with idiopathic diabetes insipidus were studied. Their condition had been identified for 2-6 years. All the patients had undergone complete clinical, neurological and endocrinological investigations during the search for the cause of their diabetes insipidus. A CT scan was performed in one patient and MRI in all four; the investigations were repeated each 6 months for 4 years. RESULTS: The first examination showed complete lack of antidiuretic hormone (four patients) and growth hormone deficiency (two patients). An enlarged pituitary stalk was seen in three patients, one patient had a small anterior pituitary, and three patients gave no posterior pituitary hypersignal. Follow-up showed that three patients completely lacked of growth hormone. One was thyrotropin deficient, three had persistent enlarged pituitary stalks, three had sub-normal anterior pituitaries and all four patients produced no post-pituitary hypersignal. None of the patients developed signs of histiocytosis or germinoma. CONCLUSION: The finding of abnormal pituitary stalks by MRI raises the possibility that the apparently idiopathic diabetes insipidus is due to some type of infiltrating disease of the hypothalamus and pituitary.

Child↗
PubMed1994

Severe aplastic anaemia--an aetiological correlation.

Over 4 years, 43 cases of severe aplastic anaemia (SAA) were seen. Etiologically 58.1% had idiopathic, 39.5% secondary and 2.3% congenital aplastic, anaemia. Idiopathic SAA was more common in patients between 0-15 years of age, whereas secondary SAA was more frequent in 16-60 years age group. Males were more commonly affected with a male:female ratio of 3.3:1. Amongst 17 cases of secondary SAA, chloramphenicol was responsible for 4, septran for 3, insecticides for 2 and anti-scabitic drugs, anti-diabetic drugs and "kushta from hakeem" in one patient each. Hepatitis associated SAA was suspected in 3 cases.

Adolescent↗
PubMed1993

Variations in DNA aneuploid cell content during tumor dissociation in human colon and head and neck cancers analyzed by flow cytometry.

Experimental research involving human solid tumors often requires single cell suspensions of high yield that are representative of the tissue of origin and in which the cellular property of interest is preserved. This is particularly necessary for the determination of DNA ploidy by flow cytometry. Mechanical dissaggregation and proteolytic enzyme digestion are the most commonly employed dissociation techniques for solid tumors. Comparative testing of techniques is often not performed. Mechanical and proteolytic enzyme dissociation techniques were comparatively tested in 77 human squamous cell cancers of the head and neck (SCCHN) and 25 human colon cancers for cellular yield, dye exclusion viability, quality, and morphology of DNA histograms, and the presence and proportion of DNA aneuploid subpopulations. Significant and consistent DNA aneuploid subpopulation losses were noted in mechanical preparations of SCCHN and enzymatic preparations of colon cancers. The frequency of SCCHN specimens with DNA aneuploid subpopulations was underestimated by 52% in mechanical cell suspensions, and the proportion of DNA aneuploid cells was diminished in an additional 30% of the specimens. Conversely, the frequency of specimens with DNA aneuploid subpopulations was underestimated by 38% in cell suspensions from enzymatically dissociated human colon cancer and their proportion diminished in an additional 50% of the specimens. Incubations of human colon cancers with three commonly employed proteolytic enzymes demonstrated a progressive loss of DNA aneuploid subpopulations as a function of enzyme concentration and incubation time. This is a serious potential source of error in the flow cytometric determination of DNA ploidy in human solid tumors, and may contribute to the diversity of results obtained and occasional contradictory conclusions reached in such studies.

Adult↗
PubMed1993

Influence of prophylactic anticonvulsant therapy on high-dose busulphan kinetics.

The pharmacokinetics of high-dose busulphan was studied in 17 patients during conditioning prior to bone marrow transplantation using deuterium-labeled busulphan (d8-BU). About 50% of busulphan doses 1 and 16 was replaced with d8-BU. Patients were treated with phenytoin or diazepam as prophylactic anticonvulsant therapy. Patients who received phenytoin demonstrated significantly higher clearance (mean +/- SD, 3.32 +/- 0.99 ml min-1 kg-1), a lower area under the concentration-time curve (AUC, 5,412 +/- 1,534 ng h ml-1; corrected for dose/kilogram) and a shorter elimination half-life (3.03 +/- 0.57 h) for the last dose of d8-BU (dose 16) as compared with the first dose (2.80 +/- 0.78 ml min-1 kg-1, 6,475 +/- 2,223 ng h ml-1 and 3.94 +/- 1.10 h, respectively). No difference in the above mentioned pharmacokinetic parameters was seen in patients treated with diazepam. Moreover, a continuous decrease in the steady-state level of busulphan was observed in four of seven patients in the phenytoin-treated group, whereas in the diazepam group, such a decrease was seen in only one of eight patients. We conclude that phenytoin used as prophylactic anticonvulsant therapy alters busulphan pharmacokinetics and, most probably, its pharmacodynamics. For adequate prophylactic therapy, anticonvulsants with fewer enzyme-inductive properties than phenytoin should be used.

Adult↗
PubMed1993

Clinical experiences and biochemical findings with tacrine (THA).

A clinical comparison of tacrine (THA) and placebo was performed in 15 Alzheimer patients using a double blind crossover technique over 4 plus 4 weeks with one drug-free week in between. Treatment results, as evaluated by clinical rating scales and neuropsychological tests, were mostly negative. Side effects were few, except for elevation liver enzymes which occurred in one third of the patients. CSF levels of the monoamine metabolites HVA and 5-HIAA increased on tacrine as evidence for activation of dopamine and serotonin pathways through cholinergic receptors. Pharmacokinetic investigations showed that the oral bioavailability of tacrine was low and greatly varying between subjects. Patients with high bioavailability of the drug tended to improve more, and also to have more liver enzyme elevations, than those with low bioavailability. A gel preparation for rectal administration was manufactured for comparison of plasma levels attained during one week's treatment with levels attained with oral capsules. Preliminary results indicate that the dose of tacrine can be reduced to 50 per cent when administered rectally, probably as by this route the rapid first-pass metabolism of the drug in the liver is diminished. A clinical trial of tacrine via the rectal route would be justified as this could decrease the number of patients with liver side effects and increase the number of patients improving on the treatment.

Administration, Rectal↗
PubMed1993

Lead encephalopathy mimicking a cerebellar tumor.

Encephalopathy is a rare but severe complication of lead poisoning, mainly due to cerebral edema. Usually diffuse, symptoms and signs are sometimes focal, suggesting a false diagnosis of tumor, particularly cerebellar tumor. We report such a case diagnosed by MR imaging in which early treatment for edema avoided neurosurgical exploration. Only six cases have been published since Biemond and Van Creveld's first report in 1939. Several data--clinical and experimental--providing specific involvement of cerebellum in lead poisoning are emphasized.

Cerebellar Diseases↗
PubMed1993

Antigen profile of Helicobacter pylori strains isolated from peptic ulcer patients in Dhaka, Bangladesh.

The whole-cell-extract and the acid-extract preparations of Helicobacter pylori strains isolated from peptic ulcer patients and the NCTC 11638 control strain were studied to compare their antigen profiles. Besides, the anti-H. pylori-antibody profile in serum from H. pylori-infected peptic ulcer patients were also studied to define the antigen stimulating specific anti-H. pylori-antibody response in the infected patients. The whole-cell extract (WCE) and the acid-extract (AE) preparations showed a general antigenic homogeneity among the H. pylori strains isolated from the patients and the NCTC 11638 control strain. A humoral immune response against the infecting organism was observed and three antigenic bands of approximate molecular masses of 61 kDa, 58 kDa and 24 kDa were recognized by all the tested sera. Those bands were found to be unique for H. pylori and did not show any cross reaction with the Campylobacter jejuni antigenic bands. This makes them a candidate for the specific antigens required to develop a specific serological diagnostic test. Further purification and characterization of the protein bands may be carried out to define their probable diagnostic or immuno-pathogenic role.

Antibodies, Bacterial↗
PubMed1993

Dose response of prophylactic antipsychotics.

A review of the literature concerning the use of oral and depot antipsychotic medication has high-lighted some important considerations in the treatment of chronic schizophrenic patients. All patients not treated with any form of antipsychotic drug will relapse within 3 years. These relapses will be more clinically significant and will occur at greater frequency than in patients who receive medication on a regular basis. Careful consideration should be given to each patient when choosing between oral or depot medication and inpatient or outpatient therapy. In addition, the clinician should consider the dosage schedule of each medication and balance this against the probability of extrapyramidal side effects and noncompliance. One option for the prevention of relapse without an increase in adverse side effects is the administration of depot haloperidol. For all therapeutic options, medication should be given on a regular basis, since intermittent dosing strategies do not work, and psychosocial rehabilitation should be initiated.

Administration, Oral↗
PubMed1992

In vivo distribution of [11C]-busulfan in cynomolgus monkey and in the brain of a human patient.

The in vivo distribution of the antileukemic agent busulfan labeled with the positron-emitting radionuclide carbon 11 was investigated in cynomolgus monkeys and in a human patient using positron emission tomography. After i.v. injection of the radiotracer, its regional uptake was monitored for about 1 h in the monkey's body and, in a separate experiment, in the monkey's brain. The concentration of radioactivity in the liver, which showed the highest levels of all the organs scanned, increased throughout the experiment and was 9-fold that in the brain at the end of the experiment. [11C]-Busulfan rapidly crossed the blood-brain barrier. The radioactivity peaked in both the cortex and the white matter showing a ratio of 1.25, at 3 min but declined quickly to yield a ratio of approximately 1 after 30 min. In the human brain, radioactivity in the cerebellum, cortex, and white matter reached a maximum within 5 min showing a cortex:white matter ratio of 1.6. The activity in the cortex declined to yield a ratio of 1 within 30 min. Of the delivered dose, 20% penetrated into the brain.

Adult↗
PubMed1992

Contribution of MR in the diagnosis of 'occult' posterior laryngeal cleft.

This paper reports three cases of 'occult' submucous posterior laryngeal cleft in which MR examination has visualized the deficiency of the posterior cricoid lamina. Laryngeal cleft is an uncommon anomaly, and its clinical and endoscopic diagnosis is always difficult. To our knowledge, the role of MR in this diagnosis has not yet been emphasized.

Cricoid Cartilage↗
PubMed1992

Effectiveness of the daily record review at the medical emergency room department in a French teaching children's hospital.

We evaluate the effectiveness of the daily record review (DRR) of 4393 ambulatory medical patients seen at the emergency room department of a teaching pediatric hospital in Paris between 8th January and 11 March 1991. For these patients, 137 potential quality problems were found, 117 of them remaining after discussion with the junior. For 80 of the 117 confirmed problems (68.4%), the reviewing senior estimated that sufficient advice had been given to the child's usual caretaker or health care provider and (or) the children returned to seek medical advice when indicated. Experts proved the procedure to be reliable: they detected a problem for 36% of the cases with potential quality problems and for only 2% of a sample of control records considered without potential quality problems after the DRR.

Emergency Service, Hospital↗
PubMed1992

On the bioavailability of oral and subcutaneous 2-chloro-2'-deoxyadenosine in humans: alternative routes of administration.

PURPOSE: The antimetabolite 2-chloro-2'-deoxyadenosine (CdA) is a promising alternative to alkylating agents for the treatment of lymphoproliferative disorders. Its use, however, is hampered by the need for intravenous (IV) administration. The aim of the present study was to determine the bioavailability of subcutaneously (SC) and orally administered CdA, and to establish an oral dose of CdA that could supersede IV administration. PATIENTS AND METHODS: A previously developed high-performance liquid chromatography method was used for the determination of plasma CdA concentrations in 13 patients. Ten patients were treated on alternate days with 0.14 mg/kg/d CdA as a 2-hour IV infusion or by a SC injection. Three of these patients were also given 0.14 mg/kg CdA orally in enteric-coated capsules. Ten patients were administered CdA orally that was dissolved in phosphate-buffered saline (PBS) after treatment with 20 mg omeprazole 1 and 6 hours before the administration of CdA. RESULTS: The bioavailability of SC CdA was 102% +/- 28% (mean +/- SD), and the bioavailability of CdA administered in enteric-coated capsules was 19%, 24%, and 60%. In the three patients who were given 0.14 mg/kg orally dissolved in PBS, the bioavailability was 48% +/- 8%, whereas in the seven patients who received 0.28 mg/kg, the bioavailability was 55% +/- 17%. In the 10 patients who were treated with the CdA solution orally, the coefficients of variation of the areas under the curve (AUCs) after oral and IV administration were similar. Thus, oral administration did not add to the interindividual variability. CONCLUSIONS: We conclude that orally administered CdA can supersede IV infusion if the dose is doubled. SC administration gives a high peak concentration of short duration with an AUC identical to that of IV infusion. Thus, SC injection can also be used as an alternative to IV infusion.

Administration, Oral↗