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Biomedical subjects

P Baxter

Publications and source records attributed to P Baxter.

At least 37 records · Page 2Linked to original sources
PubMed1997

Utrophin abundance is reduced at neuromuscular junctions of patients with both inherited and acquired acetylcholine receptor deficiencies.

Congenital myasthenic syndromes are a heterogeneous group of conditions in which muscle weakness resulting from impaired neuromuscular transmission is often present from infancy. One form of congenital myasthenic syndrome is due to a reduction of the number of acetylcholine receptors (AChRs) at the neuromuscular junction. We describe four new cases of AChR deficiency, characterized by a reduction in both miniature endplate potential amplitude and AChR abundance accompanied by elongation of the neuromuscular junction and some decrease in postsynaptic folding. A number of cytoplasmic proteins are normally associated with the postsynaptic membrane and may contribute to the clustering of AChRs at the neuromuscular junction. We therefore investigated the expression of several of these proteins in these AChR-deficiency patients. In each patient, immunolabelling of the neuromuscular junction for rapsyn, dystrophin, beta-dystroglycan and a form of beta-spectrin was strong but that for utrophin was markedly reduced or absent. This suggested that a defect in utrophin expression might underlie the congenital AChR deficiency. However, a reduction in utrophin labelling was also seen in three patients with adult acquired autoimmune myasthenia gravis in whom AChR loss results directly from the extracellular binding of autoantibodies. We conclude that the loss of AChRs in AChR deficiency does not result from the absence of rapsyn or beta-dystroglycan and that reduction of utrophin is probably secondary to the loss of AChRs. The possible role of AChRs and/or utrophin in determining the extent of postsynaptic folding is discussed.

Action Potentials↗
PubMed1996

A randomized controlled trial of laparoscopic extraperitoneal hernia repair as a day surgical procedure.

BACKGROUND: A randomized controlled trial was conducted in a day surgery setting comparing a standardized variant of the Shouldice hernioplasty with extraperitoneal laparoscopic herniorrhaphy. METHODS: The laparoscopic repair was technically challenging, evidenced by conversion from extraperitoneal to transabdominal repairs in 6.25% of patients. It was free from the inherent dangers of intraperitoneal laparoscopy. Surgical morbidity was low and comparable to that for patients randomized to the open repair. RESULTS: Outcome following laparoscopic extraperitoneal herniorrhaphy varied depending on the parameter measured. It was comparable to the open repair with respect to postoperative activity levels and the number of days required for return to work but inferior to the open repair in terms of operation time and time to hospital discharge. The extraperitoneal approach was superior to the open repair with respect to postoperative pain levels and analgesic requirements. No attempt was made to compare recurrence rates due to the short follow-up period. CONCLUSIONS: Laparoscopic extraperitoneal herniorrhaphy should not supercede conventional hernia repair until subjected to further trials with the aid of larger study populations and greater technical expertise; the results of long-term recurrence rates are awaited.

Adolescent↗
PubMed1996

Self-paced learning stations for tuberculosis respirator training: report of a pilot program.

BACKGROUND: In response to the Centers for Disease Control and Prevention's recently issued "Guidelines for Preventing the Transmission of Mycobacterium Tuberculosis in Health-Care Facilities, 1994," during May 1994 we implemented and evaluated a pilot tuberculosis respirator training program that used four self-directed learning stations, through which participants proceeded at their own pace. Employee tuberculin skin testing was included in the training program. METHODS: The time required to train each employee was recorded. At the completion of the training program, all participants were asked to assess their ability to attain the learning objectives and whether they believed the program format was an effective and efficient use of their time. Two weeks later, a convenience sample of 100 employees completed an 11-question test designed to measure knowledge retention. RESULTS: One hundred seventy-six employees completed training during the pilot period. The average time necessary to train each employee was 19.5 minutes. Overall 97.1% of participants stated that they were able to fully meet the course objectives. Test scores among the convenience sample averaged 88% 2 weeks after training. CONCLUSIONS: The use of self-paced stations for tuberculosis respirator training and employee tuberculosis skin test screening was both effective and time-efficient for employees. We have expanded this program to include all of our approximately 500 employees who may be exposed to tuberculosis.

Educational Measurement↗
PubMed1996

Co-dominant inheritance of hyperekplexia and spastic paraparesis.

In four generations of a family with autosomal dominant hyperekplexia (startle disease), untreated affected adult members had pes cavus and extensor plantar responses, as well as hyper-reflexia. Electroencephalography during a startle, electromyography, nerve conduction velocities and somatosensory evoked potentials were normal. Genetic studies showed linkage to the CSF1R locus on chromosome 5q33-q35, which includes the glycine receptor. This either represents a variant of hyperekplexia with spasticity or suggests that genes for hyperekplexia and a form of hereditary spastic paraparesis may be closely linked.

Adult↗
PubMed1996

Pyridoxine-dependent seizures: demographic, clinical, MRI and psychometric features, and effect of dose on intelligence quotient.

A regional population-based survey identified six patients with pyridoxine dependency. Four presented on the first day of life and the other two at 1 and 8 months of age. Apart from multiple seizure types, other presenting features included jitteriness; encephalopathy, at first thought to be hypoxic-ischaemic; hepatomegaly, and abdominal distension with bilious vomiting. Later problems included break-through fits with fever; transient visual agnosia; squint; severe articulatory apraxia; motor delay with later dyspraxia; macrocephaly, and post-haemorrhagic hydrocephalus. Magnetic resonance imaging showed variable structural abnormalities in all the early onset cases. Psychometric assessment revealed a stereotyped pattern of intelligence scale subtest scores, with a specific impairment of expressive verbal ability. In a prospective open study over one year, an increased dose of pyridoxine was associated with an improvement in IQ, particularly in performance subtests. Pyridoxine dependency is more common than has been thought. It has a wider range of clinical features than the classical neonatal seizures and causes specific impairments of higher function, some of which may be reversible. The dosage of pyridoxine should be optimal for IQ as well as seizure control.

Adolescent↗
PubMed1995

An epidemic of optic neuropathy and painful sensory neuropathy in Cuba: clinical aspects.

An epidemic of bilateral optic neuropathy and painful sensory neuropathy occurred in Cuba in 1991-1993. Over 45,000 individuals were stated to have been affected. We report a clinical study on 25 patients seen in Cuba in 1993-1994. Affected patients showed either bilateral optic neuropathy with caecocentral scotomata or a distal predominantly sensory neuropathy sometimes associated with deafness, or a combination of both optic and peripheral sensory neuropathy. The nature of the epidemic is discussed. The clinical features in patients with confirmed neurological deficits were consistent with a diagnosis of Strachan's syndrome, probably related to nutritional deficiency. Other patients with similar symptoms showed no evidence either of optic or peripheral neuropathy and were considered to represent disease mimicry on a psychoneurotic basis.

Adult↗
PubMed1993

Oral absorption and bioavailability of fenbendazole in the dog and the effect of concurrent ingestion of food.

Fenbendazole was administered orally without food to six beagle dogs at 2.5, 5.0, 10, 20, 40 and 80 mg/kg of body weight. Increasing the dose rate did not significantly increase the amount of fenbendazole absorbed. In a separate study fenbendazole was administered to the same six beagle dogs at a dose rate of 20 mg/kg of bodyweight in food with high, medium and low fat content. The food provided 1.52, 0.70 or 0.34 g of fat per kg of body weight. Administration of fenbendazole in food with different fat contents did not affect its relative bioavailability. Administration of fenbendazole at a dose rate of 20 mg/kg in food, irrespective of fat content, did however significantly increase its bioavailability when compared to administration of the same dose as a bolus on an empty stomach.

Administration, Oral↗
PubMed1993

Pharmacodynamics, pharmacokinetics and faecal persistence of morantel in cattle and goats.

Morantel could not be detected (< 0.05 microgram/ml) in the plasma of cattle or goats following the oral administration of morantel tartrate at a dose rate of 10 mg/kg bodyweight. No morantel was detected in the milk of lactating goats except in one animal where a concentration of 0.092 microgram/ml was detected at 8 h after drug administration. Morantel was highly effective against Cooperia oncophora infections in calves treated 6, 9 or 18 days after infection; however, was highly effective against Ostertagia ostertagi only when treated 18 days after infection. Morantel did not affect the fecundity of adult O. ostertagi surviving treatment 18 days after infection which had similar average numbers of eggs in their uteri (range 13.4 +/- 0.73-16.8 +/- 0.98) as did parasites from control animals (range 12.0 +/- 0.70-13.6 +/- 0.66). Morantel could be detected at a concentration of 96 +/- 4.5 micrograms/g (dry weight) in the faeces of a calf 24 h after treatment with 10 mg/kg bodyweight of morantel tartrate. The concentration of morantel in replicate samples of this faeces exposed to natural atmosphere, but not to soil or soil organisms, declined slowly over the following 322 days. At day 322 after the start of the experiment 8.8 micrograms/g of morantel could be measured in the remaining faecal material. Throughout the faecal degradation study the concentration of morantel in the crusts of the replicate sample pats was lower than the concentration in the core samples.

Animals↗
PubMed1993

Congenital livedo reticularis and recurrent stroke-like episodes.

Three children with pronounced livedo reticularis present since birth (cutis marmorata-telangiectasia congenita) have been followed to the ages of eight, 17 and 21 years. During childhood they developed frequent recurrent transient stroke-like hemipareses, affecting either side of the body, associated with ipsilateral pain, headache, visual symptoms, dysphasia, fits and confusion. Intellectual failure and, in one, progressive spasticity have followed. Attacks were more frequent in winter. Other problems have included abnormal peripheral vascular responses to temperature change, gastro-intestinal bleeding, glaucoma, local tissue hypertrophy and, in the two older patients, renal involvement with hypertension. Their condition represents a form of congenital vasculopathy. Anticonvulsants, anti-migraine agents, anti-platelet drugs and flunarizine have been ineffective. Nifedipine prevented further attacks in one patient and reduced attacks in another, but has not helped the third child. Adequate clothing and warmth may also be important.

Adult↗
PubMed1992

Pharmacokinetics of carprofen administered intravenously to sheep.

Carprofen was administered intravenously to sheep at two dose rates (0.7 and 4.0 mg kg-1), and the pharmacokinetics of the drug studied. Plasma concentrations of the drug were measured by high performance liquid chromatography. Carprofen had a small volume of distribution (Vd[area], 95.5 and 118.4 ml kg-1), a prolonged elimination half-life (t1/2 beta, 26.1 and 33.7 hours) and a slow body clearance rate (Clb, 2.5 ml kg-1 h-1) in sheep.

Animals↗
PubMed1991

The designated forensic professional program: a state government-university partnership to improve forensic mental health services.

As the law/mental health field has expanded and matured in the last 20 years, the sophistication required by mental health professionals in order to respond appropriately to legal questions has grown significantly. Courts and legislatures define a growing number of legal competencies. Judges and attorneys are more familiar with mental health law than they were 10 or 20 years ago.

Credentialing↗
PubMed1991

Fecundity of anthelmintic resistant adult Haemonchus contortus after exposure to ivermectin or benzimidazoles in vivo.

A strain of Haemonchus contortus resistant to the benzimidazoles, ivermectin and salicylanilides was used to study the effect of exposure to ivermectin or oxfendazole on the number of eggs produced by adult female parasites. After anthelmintic administration there was a reduction in the faecal egg count of the infected lambs. Ivermectin caused a reduction in the number of eggs within adult parasites for up to 72 hours but this returned to higher than pre-treatment levels at 168 hours after treatment. After oxfendazole treatment there was an increase in the number of eggs stored in the adult parasites at 24 hours and then a significant reduction in the number of eggs for over 168 hours. This suggested that both ivermectin and oxfendazole have a deleterious effect on the reproductive potential of female H contortus although the parasites are resistant to these drugs. These results confirm the importance of allowing up to 10 days to elapse between the time of administration of an anthelmintic and the collecting of faecal samples when using the faecal egg count reduction test to identify anthelmintic resistance, especially when using benzimidazoles. The more prolonged effect on fecundity produced by oxfendazole may reflect the antimitotic action of the benzimidazole anthelmintics.

Animals↗