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Biomedical subjects

A Dawson

Publications and source records attributed to A Dawson.

At least 109 records · Page 6Linked to original sources
PubMed1993

Anticoagulant activity of Hirulog, a direct thrombin inhibitor, in humans.

Hirulog (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095-101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers. In a randomized, placebo-controlled study (n = .54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 l kg-1 h-1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p < 0.001) and subcutaneous administration (r = 0.7, p = 0.002). To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide's activity. At the administered dose of 0.6 mg kg-1 h-1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

An unusual perilobular pattern of pulmonary interstitial fibrosis associated with Crohn's disease.

Pulmonary pathology associated with inflammatory bowel disease is rare, and seldom biopsied. In this report, we describe a case of pulmonary interstitial fibrosis associated with Crohn's disease. Biopsy showed a unique pattern, with cellular fibroblastic proliferation and fibrosis affecting interlobular septa, spreading into the parenchymal interstitium from the periphery, with associated lymphoid aggregates and thickening of arterial adventitia.

Adult↗
PubMed1993

Cor pulmonale as a complication of ventriculo-atrial shunts reviewed.

The authors present the case of a nine-year-old patient with spina bifida and hydrocephalus treated with a ventriculo-atrial shunt who developed fatal pulmonary hypertension 5 1/2 years after his last valve revision; he had been well and active up to one month before his death. Details of the dramatic cardiovascular findings are given. The problems of treatment, once symptoms occur, and the difficulty of pre-symptomatic detection are discussed.

Child↗
PubMed1993

A paramedic based emergency domiciliary obstetric service: the South Glamorgan experience.

OBJECTIVE: To assess the potential benefits of using extended trained ambulance personnel (paramedics) as primary responders for domiciliary obstetric and gynecological emergencies. DESIGN: An observational study of performance and analysis of operational data in a newly established service. SETTING: A mixed urban and rural population served by South Glamorgan Health Authority. MAIN OUTCOME MEASURES: Work load, response times, management and transfer of patients, efficiency of communications and appropriateness of training. RESULTS: There was an initial increase in requests above that when a hospital-based service operated. Targets for response times were met. The mean response time for providing appropriate skilled help was halved compared with the previous arrangements and a safe and efficient service was provided. Prompt transport and advance notice and preparation for reception in the delivery unit contributed to optimal management. Medical staff depletion in the delivery unit was minimised. CONCLUSION: An Emergency Domiciliary Obstetric Service based on primary response by specially trained ambulance service paramedics can beneficially replace traditional hospital-based Obstetric Flying Squads.

Allied Health Personnel↗
PubMed1993

Effect of bedtime ethanol on total inspiratory resistance and respiratory drive in normal nonsnoring men.

We have previously reported that bedtime ethanol (2.0 ml/kg of 100 proof vodka) increases upper airway closing pressure in males who habitually snored but were otherwise healthy. We also observed that some of these snorers developed obstructive apneas. To explore this phenomenon in more detail, we measured the inspiratory resistance (RI) and respiratory drive after bedtime ethanol in 10 nonobese men (ages 23 to 33) with no history of snoring. Subjects went to bed wearing a tightly fitting valved mask over the nose and mouth that allowed measurement of inspiratory and expiratory flow, pressure in the mask, and endtidal CO2. We measured RI by calculating the pressure difference between the mouth and a balloon positioned in the midesophagus. Respiratory drive was quantified by the inspiratory occlusion pressure (P0.1), the ventilatory response to hyperoxic hypercapnia (delta VE/delta PETCO2), and the ventilatory response to isocapnic hypoxia (delta VE/delta SaO2). Measurements were made during waking and during stage 2 NREM sleep on two nights: (1) when the subjects drank 1.5 ml/kg of 100 proof vodka in orange juice over a 30-min period 15-45 min before lights out and (2) when the orange juice contained less than 0.1 ml of vodka floating on the top. Eight of the nine men in whom we had technically adequate measurements showed a rise in RI during NREM sleep above the waking level on both control and ethanol nights and the sleeping RI was greater on the ethanol than on the control night.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Malignant mesothelioma in women.

BACKGROUND: Malignant mesothelioma reportedly shows different epidemiology and pathology in females, and a proportion are believed to arise spontaneously. METHODS: One hundred and seventy seven cases of malignant mesothelioma in females were reviewed, examined by histochemistry and immunohistochemistry, assessed for asbestosis and lung fibre burden by transmission electron microscopy with energy dispersive x ray analysis, and compared with 31 female controls. RESULTS: Two of one hundred and three cases tested for carcinoembryonic antigen were positive and were excluded from further analysis. Tumour cases showed increased amphibole burdens; in those in whom exposure information was known, 74 (80%) of 93 patients had a history of exposure to asbestos. Seventy two (47%) of 152 patients had lung fibrosis. Tumour site and histological type were little different from those reported in adult males. Mixed type histological pattern, lung fibrosis, and peritoneal site were associated with heavier lung asbestos burdens, but not exclusively. Thirty five (30%) of 117 patients had amphibole burdens of less than 2 x 10(6) fibres/g; the sites affected and the histological pattern of tumours in this group were similar to those in cases with amphibole fibre counts of > or = 2 x 10(6)/g lung. A higher lung amphibole burden than the mean burden in control females was found in 115 (98%) of 117 patients tested. CONCLUSIONS: The pathology of malignant mesothelioma appears to be similar in women and in men, and in cases associated and unassociated with asbestos.

Adolescent↗
PubMed1993

Circannual rhythms in starlings: response of castrated birds to 12-hr days depends on photoperiodic history.

The annual cycle of reproductive function in starlings (Sturnus vulgaris) is driven by seasonal changes in daylength and consists of a 6-month period of photosensitivity, culminating in maximal gonadal development, followed by a 6-month period of photorefractoriness. If male starlings are held under a constant photoperiod of 12 hr of light per day (LD 12:12), some individuals show circannual rhythms of testicular size. Do these rhythms consist of alternating periods of photosensitivity and photorefractoriness, and does the response depend on whether daylength is increased or decreased to 12 hr? Castrated starlings were transferred from natural short days in January (LD 9.5:14.5) to LD 12:12. Plasma LH decreased and then remained low for 2.5 years. Most birds molted, some twice. Other castrated birds were transferred from long days in August (LD 16:8) to LD 12:12. Plasma LH increased and then remained high for 15 months. None of these birds molted. Young starlings were exposed to LD 12:12 throughout incubation and thereafter. Plasma LH remained low until birds were 13 months old. All of these birds molted. These results demonstrate, first, that castrated starlings show no evidence of alternating periods of photosensitivity and photorefractoriness under LD 12:12; and second, that LD 12:12 can be perceived as a long day or a short day depending on photoperiodic history, and that young birds with no experience of any other daylength perceive LD 12:12 as a long day.

Animals↗
PubMed1993

Thyroidectomy progressively renders the reproductive system of starlings (Sturnus vulgaris) unresponsive to changes in daylength.

If starlings (Sturnus vulgaris) are transferred to long days soon after being thyroidectomized, they show gonadal maturation but no subsequent photorefractoriness, suggesting a specific role for thyroid hormones in the development of photorefractoriness. This study tests an alternative hypothesis: that following thyroidectomy all gonadal responses to photoperiodic changes are progressively inhibited. Photoperiodic responses of starlings were examined at two different times after thyroidectomy. Transfer of thyroidectomized birds to long days 4 weeks after thyroidectomy caused testicular growth but at a slower rate than in intact birds, whereas, in thyroidectomized birds kept on short days, testicular growth was greater than in corresponding intact birds. Thirteen weeks after thyroidectomy, there was little or no response to an increase or a decrease in daylength in thyroidectomized birds, whereas intact birds showed marked testicular growth or regression respectively. The results support the hypothesis that the reproductive system gradually becomes unresponsive to changes in daylength during the weeks following thyroidectomy. This long-term effect may mean that earlier conclusions regarding the effects of thyroidectomy need to be reassessed.

Animals↗
PubMed1992

Familial mesothelioma. Details of 17 cases with histopathologic findings and mineral analysis.

Nine new cases of mesothelioma clustering in four families are described, and additional information is provided on four previously reported families. All of the members of these families had some exposure to asbestos. Diagnoses were confirmed histologically, and the relevance of the histologic pattern is discussed after the literature review. The lung mineral fiber burden was quantified in patients by transmission electron microscopic examination and energy-dispersive x-ray analysis, and this confirmed significant exposure to amphibole asbestos in all patients. Evidence supporting an increased incidence of mesothelioma in family members is discussed.

Aged↗
PubMed1992

Efficacy of traditional Chinese herbal therapy in adult atopic dermatitis.

There has been considerable interest in traditional Chinese herbal therapy (TCHT) as a new treatment for atopic dermatitis. To establish the efficacy and safety of this treatment, a daily decoction of a formula containing ten herbs that has been found to be beneficial in open studies was tested in a double-blind placebo-controlled study. 40 adult patients with longstanding, refractory, widespread, atopic dermatitis were randomised into two groups to receive 2 months' treatment of either the active formulation of herbs (TCHT) or placebo herbs, followed by a crossover to the other treatment after a 4-week washout period. The main outcome measures were extent and severity of erythema and surface damage as judged by standardised body scores. The patients' own assessments of the overall response to treatment were also sought. The geometric mean score for erythema at the end of active treatment was 12.6 (95% confidence interval [CI] 5.9 to 22.0) and at the end of the placebo phase was 113 (65 to 180). The geometric mean score for surface damage was 11.3 (5.8 to 21.8) and 111.0 (68 to 182), respectively. The 95% CI for the mean geometric ratio for the two values with active treatment was 0.04 to 0.22 for erythema (p less than 0.0005) and 0.04 to 0.27 for surface damage (p less than 0.0005). Of the 31 patients who completed the study and expressed a preference, 20 preferred that phase of the trial in which they received TCHT whereas 4 patients preferred placebo (p less than 0.02). There was a subjective improvement in itching (p less than 0.001) and sleep (p less than 0.078) during the TCHT treatment phase. No side-effects were reported by the patients although many commented on the unpalatability of the decoction. TCHT seems to benefit patients with atopic dermatitis. Palatability of the treatment needs to be improved and its safety assured.

Administration, Oral↗
PubMed1992

Nuclear factor I is specifically targeted to discrete subnuclear sites in adenovirus type 2-infected cells.

During the S phase of the eukaryotic cell cycle and in virus-infected cells, DNA replication takes place at discrete sites in the nucleus, although it is not clear how the proteins involved in the replicative process are directed to these sites. Nuclear factor I is a cellular, sequence-specific DNA-binding protein utilized by adenovirus type 2 to facilitate the assembly of a nucleoprotein complex at the viral origin of DNA replication. Immunofluorescence experiments reveal that in uninfected cells, nuclear factor I is distributed evenly throughout the nucleus. However, after a cell is infected with adenovirus type 2, the distribution of nuclear factor I is dramatically altered, being colocalized with the viral DNA-binding protein in a limited number of subnuclear sites which bromodeoxyuridine pulse-labeling experiments have identified as sites of viral DNA replication. Experiments with adenovirus type 4, which does not require nuclear factor I for viral DNA replication, indicate that although the adenovirus type 4 DNA-binding protein is localized to discrete nuclear sites, this does not result in the redistribution of nuclear factor I. Localization of nuclear factor I to discrete subnuclear sites is therefore likely to represent a specific targeting event that reflects the requirement for nuclear factor I in adenovirus type 2 DNA replication.

Adenovirus Infections, Human↗
PubMed1992

Puberty in birds: the reproductive system of starlings does not respond to short days until birds are fully grown.

If adult starlings are kept on long days, they rapidly become refractory to long days (photorefractory). The recovery of the ability to respond to long days (photosensitivity) occurs after transfer to short days. Photosensitivity is associated with an increase in hypothalamic content of gonadotrophin-releasing hormone (GnRH), and, in castrated birds, with an increase in plasma LH. If photorefractory adult or juvenile starlings are transferred to short days, these events begin 3 and 4 weeks respectively after transfer. Starlings apparently hatch in a photorefractory state. However, if nestlings are hand-reared under short days, the increases in GnRH and LH begin at 6 and 7 weeks of age respectively. In this 3-week delay, which corresponds to the time to reach adult body size, simply due to a slower response, or are nestlings incapable of responding to short days until fully grown? Castrated male nestling starlings were hand-reared under short days, under long days or under long days initially and transferred to short days at 2, 3, 6 or 9.5 weeks of age. The increase in plasma LH in birds transferred to short days at or before 3 weeks began at the same time as in birds kept on short days (7 weeks). In birds transferred at 3 weeks or later, the increase in LH began 4 weeks after transfer, irrespective of age. Intact female starlings showed similar responses. Birds kept on short days did not moult whereas birds transferred from long days to short days at 3 weeks did.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗