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Biomedical subjects

A Dawson

Publications and source records attributed to A Dawson.

At least 127 records · Page 7Linked to original sources
PubMed1991

Enzyme replacement therapy for Gaucher disease.

Four patients with moderately severe type I Gaucher disease were treated with commercially available mannose terminated glucocerebrosidase (Ceredase; Genzyme, Boston, MA) for up to 13 months. The enzyme was administered at the rate of three to four times weekly at one fourth the total recommended dosage, greatly decreasing the cost. Marked regression of hepatomegaly and improvement in liver function tests, peripheral blood counts, and serum angiotensin-converting enzyme levels were documented. The two patients with pulmonary involvement manifested improvement in pulmonary function tests. Skeletal disease remained unchanged.

Adult↗
PubMed1991

Reactivity of the workshop monoclonal antibodies with ovine bone marrow cells and bone marrow-derived monocyte/macrophage and mast cell lines.

The workshop monoclonal antibodies were tested by flow cytometry for reactivity against: (1) ovine bone marrow cells, (2) cultured bone marrow-derived monocyte/macrophage cell lines and (3) cultured bone marrow-derived mast cell lines. Both single and two-colour immunofluorescence tests were performed. The results of these analyses are presented and discussed.

Animals↗
PubMed1991

Effect of daylength on the rate of recovery of photosensitivity in male starlings (Sturnus vulgaris).

Four groups of castrated photorefractory starlings were transferred from a photoperiod of 18 h light/day (18 L) to photoperiods of 6 L, 8 L, 11 L or 12 L. A control group was kept on 18 L. Plasma concentrations of luteinizing hormone (LH) were low in all groups initially. The first significant increase in LH, which signals the recovery of photosensitivity, occurred after 4 weeks in the groups on 6 L and 8 L, after 8 weeks in the 11 L group and after 13 weeks in the 12 L group. There was no increase in the group on 18 L. The rate of recovery of photosensitivity is therefore inversely proportional to daylength, for daylengths between 8 L and 12 L.

Animals↗
PubMed1990

Carotid endarterectomy under cervical plexus block--a prospective clinical audit.

One hundred and twenty-eight patients having carotid endarterectomy under superficial and deep cervical plexus blocks were prospectively audited. The aim of the audit was to determine the incidence of intra-operative and postoperative neurological and cardiovascular complications and to establish patient acceptance of the technique. Twenty-seven patients who had intra-operative neurological changes following carotid artery clamping responded to shunt insertion. Six patients had transient neurological changes after the operation but there were no permanent neurological complications. Tachycardia (55%) and hypertension (67%) were the most common intra-operative cardiovascular changes and there was one clinical postoperative myocardial infarction. Ninety-two per cent of patients who could be adequately assessed preferred to have the same method of anaesthesia for future carotid endarterectomy. The authors concluded that carotid endarterectomy under superficial and deep cervical plexus blocks was associated with a high patient acceptance, low neurological complication rate and an acceptable rate of cardiovascular complications.

Aged↗
PubMed1989

GTP causes calcium release from a plant microsomal fraction.

Studies on a variety of animal cell types have revealed a GTP-specific calcium-releasing mechanism in a non-mitochondrial, microsomal fraction. Here we report that GTP also induces rapid release of calcium from a zucchini (Cucurbita pepo L.) hypocotyl microsomal fraction. Maximal release occurs at 50 microM, and half-maximal release at 8 microM GTP. GTP is highly specific in its effect, and may not be replaced by UTP, ATP, CTP, TTP, GMP, or by non-hydrolysable analogues of GTP. Reuptake of calcium after release does not normally occur; however, this may be induced by non-hydrolysable GTP analogues. Calcium release is also blocked by prior treatment with these analogues.

Adenosine Triphosphate↗
PubMed1989

Neuroleptic malignant syndrome: a case report with post-mortem brain and muscle pathology.

The neuroleptic malignant syndrome is a rare but dangerous complication of treatment with neuroleptics. The aetiology and pathophysiology of the syndrome are reviewed, and a fatal case is presented where both brain and muscle pathology are described. Striking myopathic changes in this case, accompanied by only minimal and non-specific brain abnormalities, support a peripheral rather than central mechanism for the hyperthermia.

Aged↗
PubMed1989

Sexual maturation in starlings raised on long or short days: changes in hypothalamic gonadotrophin-releasing hormone and plasma LH concentrations.

Is the extended prepubertal period which occurs in most birds due to a juvenile photorefractoriness analogous to photorefractoriness in adults? Starlings were taken from nest boxes 4 days after hatching and hand-reared on long days or short days. In females on long days, hypothalamic gonadotrophin-releasing hormone (GnRH) content and plasma LH concentration remained low. In intact males on long days, plasma LH remained low and the testes remained small, and in castrated birds, plasma LH also remained low. In females reared on short days, hypothalamic GnRH content began to increase dramatically from 4 weeks of age and plasma LH increased from 6 weeks of age. In intact males on short days, there was a slight increase in plasma LH and testicular size, and in castrated males, plasma LH increased markedly from six weeks of age. All birds on long days moulted into adult plumage, whereas those on short days retained juvenile plumage. The changes in birds reared on short days were similar to those found when photorefractory adult birds are transferred to short days. This adds to the evidence that juvenile photorefractoriness is analogous to photorefractoriness in adults, and therefore that the seasonal termination of photorefractoriness is an annual puberty. However, the responses to short days occur later in birds raised on short days than in older birds transferred to short days, which suggests either that short day-induced changes occur more slowly in young birds, or that birds only respond to short days after a certain age.

Aging↗
PubMed1988

Bedtime ethanol increases resistance of upper airways and produces sleep apneas in asymptomatic snorers.

Nasal continuous positive airway pressure (nasal CPAP) and polysomnography were used to analyze the time course of the effect of bedtime ethanol on resistance of upper airways and on the number of respiratory pauses during sleep. On one night, six asymptomatic nonalcoholic male snorers drank 2 ml/kg of 100 proof vodka mixed in orange juice (ethanol dose, 0.79 gm/kg, giving a peak blood alcohol level of 71.8 +/- 33.3 mg/dl). On a second night they received a placebo (1-2 drops of vodka floated on top of the orange juice). We measured (a) the minimum nasal (CPAP) required to eliminate snoring, (b) the number of hypopneas and apneas during each hour of sleep and (c) the arterial oxygen saturation (SaO2) by ear oximetry. On the alcohol night there was a significant increase in the CPAP pressure required to eliminate snoring (placebo 4.8 +/- 1.7 cm H2O, alcohol 6.2 +/- 1.5 cm H2O). The number of respiratory events per hour of sleep (apnea index) was 7.5 +/- 2.1 for ethanol nights versus 3.8 +/- 2.7 for placebo nights (p less than 0.0125). An apnea index of greater than 5 is generally considered abnormal. There was no significant difference in the number of desaturation events (declines of 4% or more in the SaO2) or in the mean SaO2, but the minimum SaO2 was significantly lower on the ethanol night (placebo 89.8% +/- 1.6, alcohol 86.8% +/- 2.7, p less than 0.05). The effect of this dose of alcohol on airway resistance was most pronounced during the first 2 hr after ingestion.

Adult↗
PubMed1988

Effect of triazolam on sleep and arterial oxygen saturation in patients with chronic obstructive pulmonary disease.

We compared the effects of a placebo with 0.125 and 0.25 mg of triazolam (Halcion) on sleep quality, oximetry, and respiratory events during sleep in ten stable outpatients with chronic obstructive pulmonary disease. The subjects had a forced expiratory volume in 1 s ranging from 17% to 76% of the predicted value (mean +/- SD, 38.1% +/- 19%) and a waking arterial oxygen pressure from 46 to 84 mm Hg (mean +/- SD, 67 +/- 12 mm Hg). Polysomnography was done on three nights within a two-week period after the patients received on a "blinded" basis either placebo or 0.125 or 0.25 mg of triazolam. Triazolam produced improvements in total sleep duration, time spent in stage 2 nonrapid eye movement (NREM) sleep, and subjective of sleep quality. For most patients, there was a nighttime drop in arterial oxygen percentage of saturation (SaO2) in the placebo condition, but triazolam did not cause a significant worsening, of the mean SaO2, minimum SaO2, or the number of apneic and hypopneic events. Across all experimental conditions, we documented little desaturation during wakefulness (mean low, 87.2% +/- 10.2%), more during NREM sleep (mean low, 83.2% +/- 12.6%), and most desaturation in REM sleep (mean low, 80.1% +/- 15.7%). We conclude that single-night use of triazolam improved the quality and duration of sleep in patients with chronic obstructive pulmonary disease. In patients without severe waking hypoxemia and without carbon dioxide retention, triazolam did not increase either nocturnal hypoxemia or respiratory events during sleep.

Aged↗
PubMed1987

Short days induce premature reproductive maturation in juvenile starlings, Sturnus vulgaris.

Castration of juvenile and photorefractory adult starlings caused no immediate increase in circulating concentrations of LH. In castrated juveniles and adults exposed to natural changes in daylength, plasma LH increased between mid-October and mid-November, although the increase was more rapid in adults. In castrated photorefractory adults, plasma LH increased 3-5 weeks after transfer to artificial short days (8L:16D). In castrated juvenile starlings plasma LH increased 4-6 weeks after transfer to 8L:16D, irrespective of the age of the birds. Birds as young as 17 weeks had high LH concentrations. These results suggest that the reproductive system of juvenile starlings is in the same state as that of photorefractory adults, and therefore the activation of the hypothalamo-pituitary axis for the first time in juveniles is analagous to the termination of photorefractoriness in adults.

Animals↗
PubMed1987

Thyroidectomy of nestling starlings appears to cause neotenous sexual maturation.

Nestling starlings (Sturnus vulgaris) were thyroidectomized, in the wild, when 8 days old. They were later brought into captivity and hand reared on a daylength of 16h light: 8h darkness per day. Thyroidectomy dramatically affected somatic development so that even at 23 weeks of age these birds retained the physical characteristics of approximately 3-week-old euthyroid birds. Nevertheless, they appeared to be healthy and were active. Despite retaining juvenile features, these thyroidectomized birds became sexually mature. In males, testicular growth began at 8 weeks of age and by 23 weeks both males and females had well developed gonads.

Aging↗
PubMed1986

Seasonal changes in testicular size and in plasma follicle-stimulating hormone and prolactin concentrations in thyroidectomized male and thyroidectomized castrated starlings (Sturnus vulgaris).

Testicular size and plasma concentrations of FSH and prolactin were measured frequently in thyroidectomized male and thyroidectomized castrated starlings kept in outdoor aviaries during 1 year. In thyroidectomized males, testes increased from minimal to maximal size during March, remained large until June, and then decreased slowly during the next 6 months. Plasma FSH increased to a peak in April (126 micrograms/litre) and then declined slightly. Plasma FSH in thyroidectomized castrates was very high (360-760 micrograms/litre) and did not change significantly during the year. In both groups of birds, plasma prolactin concentration remained low (less than 5 micrograms/litre) and there was no molt. These results demonstrate that while thyroidectomy prevents the onset of photorefractoriness in starlings, short days nevertheless cause gonadal regression. However, this regression is not analogous to the short-day-induced gonadal regression shown by species, such as quail, which do not exhibit absolute photorefractoriness.

Animals↗