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Biomedical subjects

M King

Publications and source records attributed to M King.

At least 199 records · Page 11Linked to original sources
PubMed1995

The gelweave polyester arterial prosthesis.

OBJECTIVE: To determine the effect of the gelatin coating on the efficacy of Gelweave, a new gelatin-sealed woven polyester graft material, as an arterial prosthesis. DESIGN: In-vitro and in-vivo studies of the prosthesis. SETTING: A laboratory of experimental surgery in a university teaching institution. SUBJECTS: After in-vitro testing of the material, eight dogs were subjected to a series of in-vivo tests to evaluate the properties of Gelweave in comparison with its unsealed precursor and a commerically available collagen-coated woven polyester prosthesis. INTERVENTION: Implantation of the prosthesis as a thoracoabdominal bypass for prescheduled periods ranging from 4 hours to 6 months. MAIN OUTCOME MEASURES: Physical and chemical properties of the virgin prosthesis compared with the other two prostheses, effects of the gelatin-sealed prosthesis on healing, the hematologic characteristics of the dogs before operation and at sacrifice, microscopic studies, fibrin and platelet uptakes, prostaglandin secretion, and properties of the Gelweave grafts removed at varying periods after implantation. RESULTS: The gelatin sealant in the Gelweave prosthesis effectively reduced the water permeability of the new prototype to zero. Neither blood loss at implantation nor infection during the postimplantation period was observed. The gelatin impregnation did not cause any adverse response in the dogs and was completely lysed within 2 weeks, thus allowing encapsulation and graft healing to progress satisfactorily. After 2 weeks, the prostacyclin:thromboxane ratio was greater than 1.0, whereas the fibrin and platelet uptakes on the luminal surface of the Gelweave grafts remained low, regardless of the period of implantation. Analysis of the explanted grafts confirmed that this gelatin-sealed prototype prosthesis healed satisfactorily and no adverse biologic response occurred as a result of the gelatin coating. It maintained its biostability during 6 months in situ. CONCLUSION: The new Gelweave arterial prosthesis is ready for clinical use as a thoracic and abdominal vascular substitute.

Animals↗
PubMed1994

Incidence of psychotic illness in London: comparison of ethnic groups.

OBJECTIVE: To compare annual incidences of psychosis in people from different ethnic groups as defined in the 1991 census. SETTING: Catchment area of district psychiatric hospital. DESIGN: All people aged 16 to 54 years who made contact with a wide range of community and hospital services between 1 July 1991 and 30 June 1992 were screened for psychotic symptoms. Patients with such symptoms were interviewed face to face to collect information on demography, ethnic group, psychiatric history and symptoms, drug use, and how care had been sought. A key informant, usually a close relative, was also interviewed. MAIN OUTCOME MEASURES: Age standardised incidence of schizophrenia and non-affective psychosis according to the ninth edition of the International Classification of Diseases in each ethnic group. RESULTS: Ninety three patients took part, of whom 38 were assigned a certain or very likely diagnosis of schizophrenia (15 in white population, 14 in black, seven in Asian, and two in others). The age standardised annual incidence of schizophrenia was 2.2 (95% confidence interval 1.5 to 2.9) per 10,000 of the population. The incidence ratio for schizophrenia in all ethnic minority groups compared with the white population was 3.6 (1.9 to 7.1); the corresponding figure for non-affective psychosis was 3.7 (2.2 to 6.2). CONCLUSIONS: Raised incidences of schizophrenia were not specific to the African Caribbeans, which suggests that the current focus on schizophrenia in this population is misleading. Members of all ethnic minority groups were more likely to develop a psychosis but not necessarily schizophrenia. The personal and social pressures of belonging to any ethnic minority group in Britain are important determinants in the excess of psychotic disorders found.

Adolescent↗
PubMed1994

Quantitative pathology of nasal passages in rats exposed to urban levels of air pollution.

In order to assess the adverse effects of urban levels of air pollution, rats were used as biological indicators in a chronic exposure experiment. Animals were housed for 6 months in the center of São Paulo (the largest South American town) and compared to controls kept for the same period in a clean area. Pollution levels were obtained from a state air pollution monitoring station, 200 m distant from exposure location, which provided the levels of CO, SO2, particulates, and ozone. The nasal septum was submitted to quantitative analysis of morphological and histochemical parameters, comprising the measurement of volume of epithelium and lamina propria per unity of surface of basal lamina, the amount of mucus stored in the surface epithelium, the volume densities of neutral and acidic mucus in the lamina propria glands, and the densities of secretory and ciliated cells in the epithelium. The results obtained in the present investigation suggest that chronic exposure to urban levels of air pollution induces secretory hypertrophy, combined with a shift toward acidic mucus secretion and ciliary damage. The results are consistent with the idea that prolonged exposure to low levels of air pollution deteriorates respiratory defenses against infectious agents and may cause an increase in respiratory morbidity and perhaps mortality.

Air Pollutants↗
PubMed1994

The echogenic thalamus in hypoxic ischaemic encephalopathy.

This paper reports 16 term infants in whom an echogenic thalamus was identified on cranial ultrasonography. Fourteen of the patients suffered severe birth asphyxia. The prognostic significance of this finding and the underlying pathogenesis is assessed.

Asphyxia Neonatorum↗
PubMed1994

In vitro exposure of a novel polyesterurethane graft to enzymes: a study of the biostability of the Vascugraft arterial prosthesis.

The biostability of the Vascugraft arterial prosthesis, a porous synthetic graft made by a novel spinning process from a unique poly(ester urethane) polymer, has been studied by means of an in vitro enzyme incubation technique. Samples of the Vascugraft were exposed to buffered solutions of collagenase and pancreatin, as well as the buffer solutions alone, for periods of up to 100 days at 37 +/- 1 degrees C. On removal and after cleaning, a number of different analytic methods, including X-ray photoelectron spectroscopy for chemical analysis (ESCA), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), size exclusion chromatography (SEC), scanning electron microscopy (SEM), interference microscopy, moisture content and contact angle measurements, were used to examine the changes in chemical structure and surface morphology of the samples. During incubation in both enzymes the molecular weight of the polyurethane appeared to decrease in the presence of enzyme but increase in the presence of buffer. Further microphase separation in the polyurethane material developed during incubation in buffer solutions. Such changes in microstructure were associated with increased surface hydrophilicity, increased moisture content and a significant improvement in the extent of order and preferred orientation of the hard segment domains within the fibres. In the sampling depth of about 5 nm, both enzymes decreased the carbonate group content at the surface of the prosthesis to as little as 40% of their original values. The results from ATR-FTIR and DSC demonstrated that this phenomenon was limited primarily to the soft segment phase. While the Vascugraft prosthesis did exhibit some limited chemical modifications on exposure to concentrated enzyme solutions, nevertheless such changes were confined to the surface layer of the polyurethane microfibres. The importance and significance of those results will be more adequately determined by in vivo investigation.

Blood Vessel Prosthesis↗
PubMed1994

Spiritual and religious beliefs in acute illness--is this a feasible area for study?

In this paper we discuss the measurement of spiritual, religious and philosophical beliefs in patients admitted to hospital with acute physical illness. The discussion is based on the results of a preliminary study of the beliefs of 300 patients studied by face-to-face interview and questionnaire. Principal outcome measures at 6 months were self reported psychological and belief scores and physical state as reported in the medical records. Two thirds of patients reported a religious and/or spiritual belief system. Strength of belief was not associated with social, psychological or diagnostic factors. However, those patients with a religious and/or spiritual life view who expressed strong beliefs were likely to fare less well clinically. We conclude that empirical study of patients' beliefs is possible, though care must be exercised over the measures used. Beliefs were at least as predictive of outcome as other social and psychological factors. This area is of considerable importance to patients and should not be neglected by carers or researchers.

Acute Disease↗
PubMed1994

A controlled comparison of HIV and general medical referrals to a liaison psychiatry service.

A retrospective case-control study was performed to compare the patterns of psychiatric illness and treatment in 70 patients referred to the psychiatric liaison service from the HIV/AIDS team in a London teaching hospital with 70 age- and sex-matched controls referred for psychiatric assessment from general medical and surgical wards or out-patient clinics. Organic, mood, adjustment and personality disorders were the most common primary diagnoses. The rate of referral in the HIV group was five times that in the control group. The prevalence of each group of diagnoses was not significantly different between the HIV and control groups, except in the case of alcohol dependence (15/70 (control) v. 3/70 (HIV), p = 0.005). Forty-four per cent of the HIV group and 30% of the control group fulfilled DSM-III-R criteria for a secondary diagnosis of non-alcohol psychoactive substance abuse. A diagnosis of borderline personality disorder was made more often in the HIV group. The high frequency of psychoactive substance abuse in both the HIV and control groups has important implications for the provision of psychiatric services.

Adult↗
PubMed1994

Spinal epidural abscess: an elusive diagnosis.

This case illustrates the enigmatic fashion in which spinal epidural abscess (SEA) may manifest. In any patient with back pain and fever of unclear etiology, the diagnosis of SEA should be considered; this is particularly true when radicular symptoms are present. Some patients with SEA may not have a source of infection. SEA constitutes a neurosurgical emergency; with timely intervention, the morbid neurologic sequelae that can result once weakness or paralysis have occurred can be avoided.

Abscess↗
PubMed1994

Effects of publicity and a warning letter on illegal cigarette sales to minors.

The study aimed to assess rates of illegal cigarette sales to children and the impact on these rates of publicity and a warning letter threatening prosecution. Children aged 12 and 13 made two repeat purchasing attempts, three months apart, at 255 randomly selected tobacco retail outlets in Sydney. A randomly selected 50 per cent of retail outlets which sold cigarettes illegally at the first attempt were sent warning letters threatening prosecution. Publicity about the undercover buying operation was organised between the attempts. At the first attempts, 39 per cent of shops sold cigarettes to the children and 32 per cent sold them at the second attempt. Shops which sold on the first occasion and received warning letters reduced selling by 69 per cent compared to the 40 per cent reduction in shops which sold cigarettes on the first attempt and were not sent warning letters, a net reduction of 29 per cent seemingly attributable to the warning letters (95 per cent confidence interval 8 per cent to 50 per cent). It is extremely easy for children as young as 12 to buy cigarettes. The combined effects of publicity about undercover buying operations and warning letters threatening prosecution seem capable of reducing selling by about 29 per cent. Because of inconsistencies in selling or refusals, future attempts to measure selling rates to children should use repeat purchasing attempts and classify outlets as 'selling', 'not selling' or 'sometimes selling'.

Adolescent↗
PubMed1994

Long term non-invasive domiciliary assisted ventilation for respiratory failure following thoracoplasty.

BACKGROUND: Ventilatory failure is a well recognised complication of patients who have had a thoracoplasty for tuberculosis, but there are few data regarding the value of long term non-invasive assisted ventilation in this situation. METHODS: Thirty two patients who had had a thoracoplasty 20-46 years previously and who had developed respiratory failure were treated with nocturnal cuirass assisted ventilation or nasal positive pressure ventilation. Their survival and changes in arterial blood gases, nocturnal oximetry, and pulmonary function tests were assessed. RESULTS: The actuarial survival rates at one, three, five, and seven years after starting treatment were 91%, 74%, 64%, and 55%, respectively. Only seven of the 13 deaths were directly attributable to chronic respiratory or cardiac failure. The arterial PO2, PCO2, mean nocturnal oxygen saturation, vital capacity, and maximal inspiratory and expiratory pressures had all improved at the time of the initial post-treatment assessment (mean 12 days after starting treatment), but no subsequent improvements were seen after up to 48 months of follow up. Neither survival nor physiological improvements were correlated with the patients' age, the interval since thoracoplasty, or the pretreatment arterial blood gas tensions or results of pulmonary function tests. CONCLUSIONS: These results show that, even when ventilatory failure has developed, the prognosis with non-invasive assisted ventilation is good and the physiological abnormalities can be partially reversed. Patients who develop respiratory failure after a thoracoplasty should be considered for this type of long term domiciliary treatment.

Adult↗
PubMed1994

Ventilatory responses to hypoxia in rats pretreated with nonpeptide NK1 receptor antagonist CP-96,345.

This study reports experiments designed to evaluate the role of neurokinin-1 (NK1) receptors for substance P (SP) in the ventilatory response to acute hypoxia. Ventilation was measured by indirect plethysmography in eight unanesthetized unrestrained adult rats before and after bolus injection of 1, 5, or 10 mg/kg (ip) of CP-96,345 (Pfizer), a potent nonpeptide competitive antagonist of the SP NK1 receptor. Ventilation was measured while the rats breathed air or 8% O2-92% N2 with and without administration of SP antagonist. Pretreatment with CP-96,345 decreased the magnitude of the hypoxic response in a dose-dependent fashion. Minute ventilation in rats pretreated with CP-96,345 was reduced by 22.1% (P < 0.05) at the highest dose (10 mg/kg), largely because of an attenuation of the frequency component. Although both control and treated rats responded to hypoxia with a decrease in duration of inspiration and expiration rats pretreated with CP-96,345 displayed a smaller decrease in inspiration and expiration than control rats (P < 0.05). We have recently shown that neuropeptide-containing fibers are important for mediating the tachypnic response during acute isocapnic hypoxia in rats. The attenuation in minute ventilation at the highest dose (10 mg/kg) is comparable in magnitude to the attenuation observed with neonatal capsaicin treatment, which permanently ablates neuropeptide-containing unmyelinated fibers. Accordingly, this previously reported role of capsaicin-sensitive nerves in the hypoxic ventilatory response of rats is probably attributable to released SP acting at NK1 receptors. One of the likely sites of action of SP antagonists is the carotid body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗