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Biomedical subjects

A Roux

Publications and source records attributed to A Roux.

At least 19 recordsLinked to original sources
PubMed1992

The Johannesburg Hospital mobile anaesthesia service.

At a teaching hospital such as the Johannesburg Hospital with an air ambulance service, the need may arise for the administration of an anaesthetic outside the hospital. The occurrence of just such an event prompted the authors to review the literature regarding anaesthesia in adverse circumstances and to assemble, in a portable container, the equipment and drugs considered necessary to cope with the situation. In addition, the responsible anaesthetic personnel are receiving training in the use of the equipment and techniques required.

Aircraft↗
PubMed1992

Intramedullary epidermoid cysts of the spinal cord. Case report.

Epidermoid cysts are tumors familiar to neurosurgeons, but intramedullary epidermoid cysts are rare. The authors report the case of a 6-year-old girl presenting with progressive paraparesis. A midthoracic intramedullary mass was revealed on myelography and magnetic resonance (MR) imaging and confirmed as an intramedullary epidermoid cyst at surgery, at which time the cyst was removed. This is the fourth report documenting a purely intramedullary epidermoid cyst occurring in a child. The pathology and etiology, epidemiology, clinical features, radiology (including MR image characteristics), and surgical treatment of such rare intramedullary benign tumors are discussed. Magnetic resonance imaging reduces the delay in diagnosis of spinal cord tumors but should be guided by clinical judgment.

Child↗
PubMed1992

Postoperative hypoxaemia--its causes and prevention.

Postoperative hypoxaemia presents with varying degrees of severity. Aetiology of the condition is diverse and may originate in the pre-, intra- or postoperative periods. However, induction of anaesthesia and the type of operation are important initiating factors over which there is little control. The impact of postoperative hypoxaemia, especially when detected early, can be alleviated. This article attempts to explain the pathophysiology and provide suggestions as to detection and management of postoperative hypoxaemia.

Age Factors↗
PubMed1991

Natural inhibitors of T-cell activation in Hodgkin's disease.

Secondary immunodeficiency is frequently observed in Hodgkin's disease (HD) and is due in part to impaired T-cell function. Using monoclonal antibodies that bind to triggering molecules of human T lymphocytes (CD3/Ti antigen receptor; CD2 E-rosette receptor) and exert functional effects on T-cell activation, we have investigated in vitro immune responses of circulating lymphocytes from patients with HD in progression (n = 9) and in remission (n = 14). In patients with progressive HD, a severe dysfunction of the alternative CD2-mediated T-cell activation pathway was detected (49.3 +/- 14.2 v 9.4 +/- 5.1 cpm x 10(-3), in controls, P less than .01; n = 9) that parallels the reduced capacity of T lymphocytes to form rosettes with sheep red blood cells. Diminished alternative pathway activation in HD is not only due to a defect at the cellular level but also due to soluble mediators in the patients' plasma. Plasma from patients in progression markedly reduces CD2 mediated activation (P less than .01). These activities interfere, at least in part, with CD2/CD58 interactions and, therefore, reduce T-lymphocyte triggering through this amplifier mechanism.

Adult↗
PubMed1991

Liquid chromatographic analysis of propranolol enantiomers in human blood using precolumn derivatization with (+)-1-(9-fluorenyl)ethyl chloroformate.

A method for the determination of the R-(+) and S-(-) enantiomers of propranolol in blood was developed. After extraction with heptane-isopentanol and derivatization with (+)-1-(9-fluorenyl)ethyl chloroformate, excess reagent was removed using solid-phase extraction. The enantiomers were separated on an achiral, reversed-phase, radially compressed column, and detected by fluorescence with excitation and emission wavelengths of 260 and 340 nm, respectively. The limit of quantification was 0.5 ng/ml. This method was used for pharmacokinetic analysis of propranolol enantiomers after administration of immediate-release (80 mg) or sustained-release (160 mg) racemic propranolol.

Chromatography, High Pressure Liquid↗
PubMed1991

Influence of amiodarone on genetically determined drug metabolism in humans.

Amiodarone has been shown to interact with the nongenetically determined hepatic elimination of several drugs, including phenytoin and digoxin. Its influence on genetically determined metabolic pathways has not been studied in humans. We examined the effects of oral amiodarone therapy on the genetically determined metabolism of isoniazid (N-acetyltransferase), mephenytoin (cytochrome P450MEPH), and dextromethorphan (CYP2D6). Eight patients with arrhythmias were studied before and 76 +/- 16 days after amiodarone (loading dose of 1000 mg/day for 10 days followed by a maintenance dose of 200 to 400 mg/day). Genetically determined enzyme activity was assessed indirectly by calculating the metabolic ratio (parent drug/metabolite in 8-hour urine for CYP2D6 and P450MEPH and N-acetylisoniazid/isoniazid in plasma for N-acetyltransferase) after oral administration of the parent compounds. At the time of phenotyping, plasma concentrations of amiodarone and N-desethylamiodarone were 0.66 +/- 0.35 micrograms/ml and 0.65 +/- 0.26 micrograms/ml, respectively. Amiodarone increased the log(metabolic ratio) of dextromethorphan from a median of -2.5 (range, -2.9 to -2.0) to a median of -1.9 (range, -2.5 to -1.5; p less than 0.02) but did not alter the metabolic ratio of mephenytoin or isoniazid. The amount of dextromethorphan excreted in urine increased from a median of 0.084 mumol/8 hours (range, 0.041 to 0.161 mumol/8 hours) to a median of 0.205 mumol/8 hours (range, 0.064 to 0.288 mumol/8 hours; p less than 0.02) and the amount of its metabolite (dextrorphan) tended to decrease from a median of 26 mumol/8 hours (range, 15 to 37 mumol/8 hours) to a median of 20 mumol/8 hours (range, 7 to 27 mumol/8 hours; p less than 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Combination of long-acting furosemide and instant-acting amiloride: pharmacokinetics and pharmacodynamics in human subjects.

The pharmacokinetics and pharmacodynamics of the combination of amiloride (2 x 2.5 mg) and long-acting furosemide (2 x 10 mg) were compared with amiloride (5 mg) and furosemide (20 mg) in 12 healthy male volunteers aged 26.2 +/- 1.6 years and weighing 68.8 +/- 6.2 kg, after random order administration. Furosemide and amiloride plasma or urine concentrations were determined by HPLC with fluorimetric detection. The rate of absorption (tmax = 3 h) and the bioavailability of the two diuretics were not significantly modified by their combination. Furosemide plasma half-life was 2.77 +/- 1.04 h after the combination treatment and 2.76 +/- 0.98 h alone, amiloride plasma half-life was respectively 15.7 +/- 4.6 h and 14.6 +/- 3.7 h. The urinary elimination of furosemide was significantly higher in the 2-4 h interval in the combination treatment, accompanying its delayed maximum effect of diuresis. A synergistic effect was observed after the combination administration of the two diuretics; between the 2nd and the 8th hour, the sodium elimination was significantly increased (P less than 0.01) and the potassium excretion was significantly decreased (P = 0.05). After a single dose, no modification of plasma or erythrocyte magnesium levels was observed. This study shows that the combination of the two drugs entails a synergy of their activities which does not involve pharmacokinetic changes.

Adult↗
PubMed1991

Vasoconstrictor effects of adrenaline in human septic shock.

In an open prospective study, adrenaline administration in ten patients with eleven episodes of septic shock was studied. Appropriate supportive therapy (antibiotics, laparotomies, parenteral alimentation, ventilation) was given as needed. Haemoglobin was kept at or about 12 g%, pulmonary capillary wedge pressure kept at approximately 15 mmHg, and cardiac index at greater than 4.5 l/min/m2. Only when systemic vascular resistance (SVR) dropped below 600 dyn. s. cm-5 was adrenaline given to raise the latter to no higher than 800 dyn. s. cm-5 and the adrenaline was titrated to this end point. Adrenaline was used at doses up to 0.47 microgram/kg/min for up to nineteen days. There was no reliable dose response curve for adrenaline: each septic insult needed different dosages. However, if high enough doses were given, SVR eventually increased. There was no deterioration in cardiac index nor further increase in pulse rate and no renal damage was demonstrated. Only one patient died in septic shock. Two others died from causes not directly related to sepsis and another two while still in hospital, but again not septic. Five patients were eventually discharged from hospital. Adrenaline can thus be used as a vasoconstrictor in septic shock without adverse effects, but initial doses have to be high and the effects measured and titrated carefully. Used this way, adrenaline provides time for the eradication of sepsis.

Adult↗
PubMed1991

[Pharmacokinetics of aspirin in African children with normal nutrition and malnutrition].

Pharmacokinetics of aspirin given orally at antipyretic dose (12 mg/kg) were studied in 11 African children aged 4-48 months. In order to examine the influence of nutritional status on aspirin kinetics, children were classified according to Waterlow criteria. Blood samples were collected during the 8 hours following the initial dose. Albumin, prealbumin and transferrin plasma levels were measured and plasma salicylic acid (SA) concentrations determined by a fluorometric method. Nutritional status seemed to have no prominent effect on plasma concentrations of SA. The volume of distribution found in our study was lower than those obtained in other studies. This could be explained by lower plasma aspirin esterase activities in black children. There were large individual variations in plasma salicylate concentrations. For example, even at antipyretic doses, saturation phenomena appeared in two children.

Aspirin↗
PubMed1991

Spinal man after declaration of brain death.

Complex spinal automatism in a patient who was declared brain dead is described. These movements tend to appear once cerebrospinal shock has abated. We postulate that these manifestations are a reflection of the physiological potential of the isolated spinal cord. These spinal movements should be included in the revised guidelines for the determination of cerebral death.

Adult↗
PubMed1990

[Treatment with sustained theophylline release. Monitoring by salivary assay in children].

We have tested the possibility of replacing plasma assays by salivary assays of theophylline for the monitoring of sustained-release theophylline therapy in asthmatic children. In a first group of 40 children aged 7.2 +/- 3.3 years (mean +/- SD) treated with sustained-release theophylline in mean daily doses of 18.8 +/- 5 mg/kg, 77 plasma and saliva samples were taken simultaneously 6 hours after the morning dose (6 H). Saliva was collected after mouth-wash and stimulation with 10 mg of citric acid. Assays were performed using the EMIT method. Theophylline plasma concentrations (P) and salivary concentrations (S), both expressed as mumol/l, were found to correlate: P = 1.58 S + 8.7 (P less than 0.0001). In a second group of 33 children, 39 simultaneous samples were taken at 6 H. From the equation previously obtained the plasma concentration corresponding to each salivary concentration was calculated, and the calculated value was compared with the measured value. The difference between the two values was 7.1 +/- 9 mumol/l. On this basis, and because the method is non-invasive and painless, were are now using salivary assays (under strict conditions of collection and measurement) to verify the patients' compliance and to maintain or adjust dosage in asthmatic children.

Adolescent↗
PubMed1990

Causes of mental handicap in Cape Town.

A cross-cultural study of the cause of the mental handicap of greater than 1,000 children born in the Cape Town area between 1974 and 1986 was carried out. Acquired causes were noted to be more prevalent among the black ethnic group. This study showed that at least 80-100 additional cases of moderate-severe mental handicap can be expected in the Cape Town area each year. Attention is drawn to the expanded facilities that will be required to provide for the ongoing special needs of these children. Possible areas for prevention of mental handicap are discussed.

Adolescent↗
PubMed1990

Vertebro-PICA aneurysms: midline suboccipital approach and laminectomy of the atlas.

Vertebro-PICA aneurysms represent a particular technical challenge because of the extremely narrow operative field and the presence of numerous vital neural and vascular structures. The lack of exposure still remains the limiting factor in most cases. During the 9-year period from January 1980 to October 1989, 8 vertebro-PICA aneurysms have been treated microsurgically. Of these, 2 underwent a pure suboccipital approach while 6 underwent a midline suboccipital approach with deliberate removal of the arch of the atlas in the park bench position. Seven patients did well and regained full activities while one patient died from complications related to vasospasm with brainstem infarction. One patient developed symptomatic obstructive dilation of the fourth ventricle requiring ventriculo-cisternostomy. The authors recommend the midline suboccipital approach with deliberate C1-laminectomy in ventrolateral decubitus for vertebro-PICA aneurysms. The main advantages are: constant access to the proximal vertebral artery, less medullary retraction in ventrally located aneurysms, improved exposure of the laterobulbar cisterns and the lateromedullary and tonsillar segments of the PICA, thus facilitating dissection of the aneurysm.

Adult↗
PubMed1989

Natural mode of horizontal transmission of bovine leukemia virus (BLV): the potential role of tabanids (Tabanus spp.).

In order to evaluate the potential role of hematophagous insects in the natural spreading of bovine leukemia virus (BLV) infection in cattle, a 2-year survey was carried out involving sequential serological tests on 3328 cattle in three different areas. A parallel entomological study was run over the same period, using continuous trapping, in order to determine both the density and variations of horsefly (Tabanus spp.) populations in the close vicinity of the herds. After statistical analysis, this space-time study showed that: (1) There is a significant positive geographical correlation between the rate of incidence of BLV infection and the density of the horsefly population. (2) Seasonal variations in the incidence rate exist; the highest rates are generally observed during summer (from July of September), and the lowest during winter, spring and early summer (from November to mid-July). (3) There is a time link between the rate of sero-conversion and the variations in activity of the horsefly population. All these data combined would appear to indicate that tabanids play a considerable role in the spread of BLV under natural conditions.

Animals↗