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Biomedical subjects

R D Watson

Publications and source records attributed to R D Watson.

At least 19 recordsLinked to original sources
PubMed1992

Patients with suspected myocardial infarction: effect of mode of referral on admission time to a coronary care unit.

The aim of this prospective study was to determine the delay between the onset of symptoms and arrival in the coronary care unit of patients with suspected acute myocardial infarction, and the relative contribution to the total delay of patient delay, method of referral (self referral or general practitioner referral) and delay in the hospital before reaching the coronary care unit. All patients admitted with chest pain to the coronary care unit at Dudley Road Hospital, Birmingham, over the six month period April-September 1989 were included in the study. Ninety five patients were referred by their general practitioner and 107 patients attended the accident and emergency department directly or arrived by ambulance without contacting their general practitioner. The proportion of self referred and general practitioner referred patients with acute myocardial infarction, angina and non-cardiac chest pain were not significantly different. The total delay was significantly longer for patients who had been referred by their general practitioner (median 5.3 hours) than for self referrals (3.2 hours, P less than 0.001), with a significantly higher proportion of self referrals arriving at the coronary care unit within six hours of the onset of symptoms (77% versus 54%, P less than 0.01). Among general practitioner referrals, initial patient delay accounted for a median of 2.5 hours and the general practitioner's response time for a median of 1.1 hours. The delay in hospital was similar for both groups of patients. In inner city areas, self referral may result in considerably less delay than general practitioner referral allowing a greater proportion of patients to receive effective thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Care Units↗
PubMed1991

Computer graphics representation of a statistical model used with computer-aided diagnosis.

A description of computer graphics of a multidimensional model that is used with computer-aided diagnosis or prognosis is presented. The model is discussed and computer graphics of the model are developed. The computer graphics are suitable as visual supplements for presenting the computer-aided diagnostic model to individuals who may be inexperienced in multivariate statistics.

Animals↗
PubMed1991

Influence of racial origin on admission rates of patients with suspected myocardial infarction in Birmingham.

All patients with suspected myocardial infarction admitted to hospital in four Birmingham health districts were studied to test the hypothesis that Asian patients would be overrepresented and Caribbean patients underrepresented compared with the indigenous population. One thousand four hundred and ninety six patients had a final diagnosis of myocardial infarction or severe angina pectoris. The relative risk of admission for Asian men compared with white men aged 45-64 years was 2.65 (95% confidence interval 2.20 to 3.19) and the risk for Asian men was high for both myocardial infarction and ischaemia when analysed separately. The relative risk of admission for Caribbean men compared with white men was 0.53 (95% CI 0.33 to 1.20). The relative risk for Asian women compared with white women in the same age group was 2.58 (95% CI 1.68 to 3.96), but this was due to an excess of admissions diagnosed as ischaemia rather than infarction in the Asian women. For Caribbean and white women the risk of admission was the same, although significantly fewer Caribbean women were admitted with myocardial infarction. The study was undertaken in 1986-87 and population data had to be derived from the 1981 census. The resident population changed in those five years and so the results were recalculated making allowances for these changes in the health districts involved. Based on these data the admission rate for Asian men with suspected myocardial infarction aged 45-64 was nearly twice that for white men (1.8): the relative risk of admission for Asian men compared with white men was 2.04 (95% CI 1.53 to 2.18). For Caribbean men the relative risk compared with white men was 0.45 (95% CI 0.29 to 0.71). For Asian women the relative risk of admission calculated from the adjusted census data resemble that in white women aged 45-64 years. The relative risk for admission with coronary heart disease in Asians is higher than expected work; one possible explanation for this is that the Asian population resident in the area under study was larger than estimated. The single major difference in risk factors was the high prevalence of diabetes mellitus in Asians (19.5% compared with 8.3% for white residents) but this did not wholly account for the excess of admissions from the Asian community.

Asia↗
PubMed1990

Treatment of postural hypotension. A review.

Many drugs have been used in treating patients with postural hypotension but for a large number the evidence of benefit is small and the potential for adverse effects, particularly supine hypertension, is great. Full clinical assessment is essential at the outset to define the nature and extent of pathophysiological disturbance of autonomic function. Many patients can be treated adequately by sleeping with the head of the bed elevated, and the use of fludrocortisone. Patients without evidence of central neurological deficit may benefit from additional treatment with drugs which alter beta-adrenoceptor tone. Patients who respond poorly to these measures should be admitted to hospital, and treatment with desmopressin initiated. Symptomatic postprandial hypotension should be identified early since the response to these measures alone is often poor, caffeine administered before eating, with abstinence for the rest of the day, may be very helpful.

Humans↗
PubMed1989

Regulation of ecdysteroidogenesis in prothoracic glands of the tobacco hornworm Manduca sexta.

Ecdysteroidogenesis in Manduca sexta prothoracic glands is regulated by a set of bioregulatory molecules, including prothoracicotropic hormone (PTTH) and a protein factor present in larval hemolymph, and by the competence of the glands to synthesize ecdysteroids in response to those molecules. A larval molting bioassay was used to assess the in vivo activity of Manduca PTTHs. Crude PTTH, big PTTH, and small PTTH each elicited a larval molt in head-ligated larvae. However, big PTTH was approximately 10-fold more potent than crude PTTH, which was, in turn, several orders of magnitude more potent than small PTTH. When big and small PTTH were combined, the molting response was similar to that elicited with crude PTTH. The chemical nature of the hemolymph protein factor was also investigated. Injection of [3H]cholesterol into last-instar larvae and fractionation of the radiolabeled hemolymph by gel filtration chromatography revealed three peaks of radioactivity. One peak eluted in fractions containing the hemolymph protein factor, a result consistent with the notion that the factor transports a sterol substrate. The possibility that the factor is a 3(2)-ketoreductase was investigated by assessing the effect of the factor on the accumulation of RIA-detectable ecdysteroids in prothoracic-gland-conditioned medium. Three of five preparations of the factor significantly enhanced the amount of RIA-detectable ecdysteroids in conditioned medium, indicating that at least some preparations of the factor may contain ketoreductase activity. The above findings are discussed in the context of current hypotheses of how bioregulatory molecules interact with the prothoracic glands to regulate ecdysteroidogenesis in Manduca.

Animals↗
PubMed1989

Evidence that Y-organs of the crab Cancer antennarius secrete 3-dehydroecdysone.

Y-organs are paired glands in crustaceans that secrete a class of steroid hormones (ecdysteroids) that regulate growth, molting and development. The glandular secretion has been assumed to be solely the ecdysteroid, ecdysone, a polyhydroxylated derivative of cholesterol. We previously reported that Y-organs of a crab (Cancer antennarius) additionally secreted an ecdysteroid that is less polar than ecdysone. Evidence is presented here that the other secretion product is 3-dehydroecdysone (3-dhE). The compound co-chromatographed with authentic 3-dhE in both normal-phase, and reversed-phase, high-performance liquid chromatography. Mass spectrometry of the ecdysteroid gave results consistent with its identity as 3-dhE. The putative 3-dhE was radiolabeled by injecting crabs with [3H]cholesterol and then incubating the Y-organs. The putative [3H]3-dhE secretion was then subjected to chemical reduction. The reaction yielded labeled products that co-chromatographed with authentic ecdysone and 3-epiecdysone. Results of other experiments gave the following results: (1) Putative 3-dhE was not altered (chromatographic criteria) by incubations with snail hydrolases. (2) Putative [3H]3-dhE, added to incubations of Y-organ halves or homogenates, was not significantly converted to ecdysone; also, no conversion was evident after incubation in medium alone in which the hemolymph serum supplement was raised to 50% of the volume. (3) [3H]Ecdysone was not converted to putative 3-dhE in vitro by Y-organ halves or homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Skin tags are not a risk factor for colorectal polyps.

To ascertain whether acrochordons (simple skin tags) are associated with a higher risk for colon polyps, we prospectively studied 218 male and female patients, age 40 or older without history of colon cancer, polyps, ulcerative colitis, familial polyposis, or recent lower intestinal symptoms. Each patient was assessed for the presence of skin tags. A screening flexible sigmoidoscopy was then performed without knowledge of the dermatologic findings. All polypoid lesions were recorded, and patients with polyps greater than or equal to 3 mm in diameter underwent full colonoscopy and polypectomy. Twenty patients (9.2%) had documented adenomatous polyps on colonoscopy. Nineteen other patients had hyperplastic polyps and mamillations. There was no significant difference in the prevalence of polypoid lesions in those with skin tags compared with those without skin tags, either analyzed as group totals or stratified by age, sex, or type of polyp. We conclude that skin tags are not associated with a higher than usual risk for colonic polyps and should not be used as a marker for more intensive screening.

Adult↗
PubMed1989

Unruptured aneurysm of the sinus of Valsalva presenting with isolated heart block: echocardiographic diagnosis and successful surgical repair.

A 31 year old man presented with intermittent dizziness and electrocardiographic evidence of a severe conduction disturbance, with asystolic pauses of up to six seconds, and was treated by implantation of a permanent pacemaker. Echocardiography showed an enlarging aneurysm of the right sinus of Valsalva extending into the interventricular septum. This was confirmed by aortography, and successful surgical repair was carried out. The characteristic diastolic expansion of the aneurysm and the demonstration of continuity between the septal extension and the related aortic sinus were useful diagnostic features.

Adult↗
PubMed1989

The catecholamine content of a cystic phaeochromocytoma.

We report a case of phaeochromocytoma in which the tumour was a single 10 cm adrenal cyst. The cyst fluid contained noradrenaline and adrenaline in concentrations 100 to 200 fold higher than are seen in the serum of phaeochromocytoma patients. Possibly cystic tumours containing large amounts of catecholamine may if inadvertently compressed at operation, present a greater surgical hazard than solid tumours.

Adrenal Gland Neoplasms↗
PubMed1988

Skin tests.

Explore the source record for details and available documents.

Allergens↗
PubMed1988

Plasma catecholamine levels in acute myocardial infarction: influence of beta-adrenergic blockade and relation to central hemodynamics.

In a prospective study, 20 patients with acute myocardial infarction were randomly assigned in a double-blind fashion to treatment with intravenous metoprolol followed by oral metoprolol or placebo. All patients underwent hemodynamic monitoring for 24 hours. Plasma adrenaline and noradrenalin levels were estimated at baseline (mean 6.0 +/- 0.9 hours from onset of symptoms) and at 1 and 24 hours after the start of therapy. Plasma adrenaline and noradrenalin levels were elevated in all but one patient, with a further increase at 1 hour after administration of metoprolol (p less than 0.05). At baseline pulmonary capillary wedge pressure was directly related to both plasma adrenaline (r = -0.44; p less than 0.05) and noradrenalin levels (r = -0.44; p less than 0.05). There was also an inverse relationship between stroke volume index and the plasma noradrenalin level (r = -0.44; p less than 0.05) but not the plasma adrenaline level. These relationships were lost after the baseline measurements. However, between baseline and 1 hour there was a close relationship between the change in systemic vascular resistance and the changes in both adrenaline (r = -0.48; p less than 0.05) and noradrenalin levels (r = -0.66; p less than 0.01). Thus, in the early stages of myocardial infarction high plasma catecholamine levels are associated with the hemodynamic markers of severe left ventricular damage. Beta-adrenergic blockade with metoprolol produced a further increase in catecholamine levels that was associated with an increase in systemic vascular resistance.

Administration, Oral↗
PubMed1988

Juvenile hormone regulates the steroidogenic competence of Manduca sexta prothoracic glands.

The acquisition of steroidogenic competence by prothoracic glands of last instar Manduca sexta larvae is regulated by juvenile hormone (JH). Topical treatment of pre-commitment larvae with JH I or (7S)-hydroprene (a JH analog) delays development by increasing the time to pupal commitment and wandering. Prothoracic gland competence is suppressed in JH-treated larvae: Unstimulated and prothoracicotropic hormone (PTTH)-stimulated rates of in vitro ecdysone secretion are decreased relative to rates of secretion by competent glands. (7S)-Hydroprene also suppresses the competence of glands in head-ligated pre-commitment larvae, suggesting the hormone acts directly on the glands. Two results indicate PTTH plays a role in controlling competence, and that JH regulates competence indirectly by inhibiting PTTH release: (1) head-ligation prevents the acquisition of full competence, and (2) cAMP levels are elevated in glands from JH-treated larvae. Thus, the decrease in the JH titer that precedes pupal commitment in Manduca is permissive for the acquisition by prothoracic glands of steroidogenic competence.

Animals↗
PubMed1987

Regulation of juvenile hormone biosynthesis by 20-hydroxyecdysone during the fourth larval instar of the tobacco hornworm, Manduca sexta.

A previous study of the role of 20-hydroxyecdysone in the regulation of juvenile hormone (JH) biosynthesis during pupal commitment in the last (fifth, V) larval instar of Manduca sexta revealed that the increase in the hemolymph edysteroid titer that elicits commitment also stimulates the corpora allata (CA) to synthesize JHs I and III and/or their acids. This stimulation is exerted indirectly via the brain-corpora cardiaca and results in the postcommitment increase in the JH titer that is important for the molt to a pupa. The possibility that a similar form of interendocrine regulation of JH biosynthesis by 20-hydroxyecdysone is involved in the control of larval molting in Manduca was investigated for the molt from the fourth (IV) to the V larval instar. During the IV instar, the increase in the hemolymph ecdysteroid titer and the capacity of the CA to synthesize JHs I and III in vitro correlated temporally in a manner suggestive of CA regulation by 20-hydroxyecdysone. With an in vitro approach, physiological concentrations of 20-hydroxyecdysone (greater than or equal to 1 microgram ml-1 hemolymph) were shown to have a dose-dependent trophic effect on CA activity, specifically stimulating JH I synthesis. Since neither basally active nor stimulated CA contained significant amounts of JH I, it appears that 20-hydroxyecdysone acts at the level of biosynthesis rather than at the level of release. The specificity of 20-hydroxyecdysone stimulation of JH I synthesis was demonstrated by the inability of the biologically inactive ecdysteroids 22-isoecdysone and 5 alpha-ecdysone to activate the glands.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Variation in cuff blood pressure in untreated outpatients with mild hypertension--implications for initiating antihypertensive treatment.

Thirty-two patients with mildly elevated blood pressure (BP), but without target organ damage, attended a BP measuring clinic where duplicate BP measurements were made on 12 visits. During visits 1-3, BP showed a systematic decrease which varied from patient to patient. During visits 4-12, no further systematic changes in BP were observed. During the latter period, between-visit variation in BP was substantial, the standard deviation of the difference in BP from one visit to another being 10.4 mmHg for systolic, 6.8 mmHg for diastolic (phase IV) and 7.0 mmHg for diastolic (phase V). These values were used to determine the chance that the BP estimated after a number of visits differed from the average stable BP. After visit 4, the chance of a difference of 5 mmHg or more was 0.50 systolic blood pressure (SBP) and 0.32 diastolic blood pressure (DBP; phase V). Increasing the number of visits to six or more reduced the chance of error. Before initiating lifelong treatment in mild hypertensives free of target organ damage, BP should be recorded in duplicate on a minimum of six visits.

Adult↗
PubMed1987

Amiodarone-induced pulmonary toxicity mimicking metastatic lung disease.

A 65 year old man developed atrial arrhythmias secondary to a congestive cardiomyopathy which were resistant to quinidine and disopyramide. Amiodarone controlled the paroxysmal atrial tachycardia but 4 months after starting the drug he developed increasing dyspnoea and radiological changes highly suggestive of metastatic lung disease. Lung biopsy showed change of drug-induced pneumonitis and 4 months after stopping amiodarone his symptoms resolved and the chest X-ray had cleared. Amiodarone may cause pulmonary toxicity mimicking metastatic lung disease.

Aged↗