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Biomedical subjects

S Arnold

Publications and source records attributed to S Arnold.

At least 163 records · Page 9Linked to original sources
PubMed1987

Community outbreak of adenovirus type 7a infections associated with a swimming pool.

In July 1982, an outbreak of pharyngitis caused by adenovirus type 7a occurred among children in a small town in western Oklahoma. Predominant symptoms were fever and sore throat (by case definition), headache (83%), abdominal pain (64%), and conjunctivitis (51%). At least 77 persons were identified whose symptoms met the case definition for illness. Onsets of illness peaked during the week of July 5 to 12, and the outbreak resolved within three weeks. A systematic telephone survey of the town revealed that persons who had swum at the community swimming pool were more likely to be ill than those who had not (P less than .001). A second survey of families with season passes to the pool showed that among swimmers, illness was directly related to average number of hours of exposure to the pool each week (P less than .001 by chi-square for trend). In addition, swimmers who reported swallowing pool water were more likely to be ill (29 of 56, 52%) than persons who did not (ten of 41, 24%) (P = .01). Throat-swab specimens from five of seven ill persons (71%) grew adenovirus 7a compared with one of 12 well persons (8%) (P = .01). The pool chlorinator had reportedly malfunctioned during early July. The outbreak resolved with proper operation of the chlorination system. Swimming pools continue to be a potential source of community-wide outbreaks of adenovirus infections.

Adenoviridae Infections↗
PubMed1986

[Diagnostic and prognostic significance of so-called rheumatoid vasculitis--2].

51 patients with rheumatoid arthritis and high rheumatoid factors (mean titres 928) underwent examination for the demonstration of an extraarticular organ manifestation within the scope of the cooperation between the Department of Medicine of the Karl-Marx-University Leipzig and the Institute for Rheumatology of the Academy of Medical Sciences of the USSR in Moscow. The frequency of nodous rheumatism (about 60%) is comparable with the frequency of polyneuropathy. In 20% of the patients a systemic muscle atrophy, a hepatomegaly as well as a Raynaud-syndrome were stated. By means of skin biopsy in 28% perivascular infiltrates were found. Altogether in 6 patients (12%) a participation of the lungs and the pleura, respectively, could be proved. Only rarely a clinically manifest heart disease caused by the rheu-we we found an pericardial effusions in 3 cases. In systemic manifestation, such as myositis, participation of the eyes or vasculitis of the digital arteries with necrosis, were only sporadically to be established. Among 22 patients we found an pericardial effusions in 3 cases. In systemic manifestation in most cases increased parameters of activity were found. From the practical point of view apart from increased titers of the rheumatoid titres and circulating immune complexes (C1q-BT) increased concentrations of the C-reactive protein are prognostically significant. The presence of high rheumatoid factor titres alone as well as the isolated presence of rheumatic nodes must not always be connected with an unfavourable prognosis. When severe extraarticular manifestations are present a possibly early, intensive occasionally extracorporeal treatment is indicated.

Adolescent↗
PubMed1986

Impending cardiac herniation: the snow cone sign.

Two cases of cardiac herniation and volvulus that occurred after right pneumonectomy are presented. Both asymptomatic patients demonstrated an unusual bulging contour to the right side of the heart on radiographs obtained in the recovery room, before complete herniation and volvulus occurred. In an autopsy preparation, a similar right contour was produced after partial cardiac herniation through a pericardial defect. The hemispheric contour from partial cardiac herniation resembles the shape of a snow cone. Clinical awareness of this sign of impending herniation is important, so risk factors known to produce herniation may be modified.

Adult↗
PubMed1982

Insulin infusion in conscious dogs. Effects on systemic and coronary hemodynamics, regional blood flows, and plasma catecholamines.

Cardiovascular actions of insulin were studied by intravenous infusions of insulin (4 and 8 mU/kg per min) in normal conscious dogs. This resulted in increases in cardiac output, heart rate, and left ventricular derivative of pressure with respect to time (dP/dt) and dP/dt/P, as blood glucose was reduced. The inotropic and chronotropic effects of insulin were not related to hypoglycemia, as they persisted even when blood glucose was restored to control values or when it was prevented from falling by a simultaneous infusion of glucose. These cardiac effects were accompanied by increases in plasma catecholamines, and were abolished by propranolol pretreatment. Both plasma epinephrine and norepinephrine increased during insulin hypoglycemia, but only norepinephrine increased during insulin infusion when euglycemia was maintained. Mean arterial blood pressure did not change significantly during insulin hypoglycemia, but rose if euglycemia was maintained, probably due to the selective increase in norepinephrine in the latter condition. A pressor response also occurred in propranolol-pretreated dogs during insulin hypoglycemia, but was abolished when the animals also had been pretreated with phentolamine, indicating that the vasoconstrictor action of insulin was mediated via alpha adrenergic receptors. Insulin infusion increased left ventricular work and myocardial blood flow in dogs with and without hypoglycemia. Myocardial blood flow, however, did not change significantly during insulin infusion in dogs pretreated with propranolol. As propranolol also diminished the inotropic response, it appears that the increase in myocardial blood flow caused by insulin in the normal dog is causally related to the increased myocardial metabolic demand. Insulin also produced vasomotor effects on other vascular beds. In skeletal muscle, blood flow was increased under all study conditions, except during insulin hypoglycemia after propranolol-pretreatment when unopposed alpha-mediated vasoconstriction was present. The persistent increase in flow during both alpha and beta adrenergic blockade suggests that insulin has a direct dilator effect on skeletal muscle vasculature. In the adrenal gland, flow was increased except during euglycemia, when no rise in plasma epinephrine was observed, suggesting coupling between adrenal flow and catecholamine release. In the splanchnic bed, flow was decreased during euglycemia, when plasma norepinephrine rose, and during beta adrenergic blockade with propranolol, when unopposed alpha-mediated vasoconstriction also predominated. A similar pattern was found in the kidney, except that renal blood flow also fell after combined alpha and beta adrenergic blockade. The results show that the vasomotor effects on regional flows are mediated both via adrenergic mechanisms, and in the case of skeletal muscle and kidney, via mechanisms unrelated to sympathetic stimulation.

Adrenergic beta-Antagonists↗
PubMed1981

Contrast enhancement of thallium-201 myocardial scintigrams: improved sensitivity with diminished specificity in coronary disease detection.

Thallium-201 myocardial scintigraphy (TMS) has become an increasingly popular noninvasive technique with a high diagnostic specificity, but a somewhat lower sensitivity for coronary disease (CAD) detection. Many centers now routinely employ computer techniques to contrast enhance scintigrams, but the resulting changes in sensitivity and specificity have not been carefully evaluated. In the present study, three observers with different levels of experience blindly interpreted both unprocessed and enhanced exercise TMS from 40 patients with CAD and from 15 without significant obstructions. The sensitivity for CAD achieved by each observer was higher with the enhanced scintigrams (increase from an average of 80% to 93%), but there was concomitant loss of specificity (from 93% to 73%). Similarly, significant changes were present in the sensitivity and specificity with which ischemic regions were diagnosed. In addition, contrast enhancement facilitated interpretation of TMS studies, particularly in making comparisons between exercise scintigrams and subsequent rest or redistribution images. Contrast enhancement affected the interpretations of the inexperienced observer most significantly. We conclude that contrast enhancement improves TMS sensitivity but results in some loss of specificity. The variable effect of enhancement on observers with different levels of experience suggests that laboratories should critically evaluate their own results before routinely employing computer processing.

Computers↗
PubMed1981

Hemodynamic effects of prazosin in chronic heart failure.

Three series of investigations were carried out with prazosin (PZN) hydrochloride. In the first, hemodynamic effects of PZN were compared with those of hydralazine (HDZ) in 11 patients with chronic congestive heart failure (CHF). In doses up to 5 mg, PZN increased cardiac output (CO) 20% accompanied by a 20% decrease in pulmonary capillary wedge pressure (LVFP). HDZ increased CO by 50% with little or no effect on LVFP. An additional 12 patients were given multiple 5 mg doses of PZN at 6-hour intervals with measurements of hemodynamic and plasma blood levels. Results suggested an attenuation of the effects of PZN on increasing CO but not on decreasing LVFP. This attenuation of CO was not due to inadequate plasma levels. Acute exercise studies (supine bicycle) were performed in 10 patients with severe CHF before and after the administration of several doses of PZN. There appeared to be a greater effect of PZN during exercise than at rest, with a beneficial increase in CO and reduction in LVFP. These data suggest that, despite hemodynamic attenuation of its effects on CO at rest, PZN may still be beneficial to active patients with CHF. In vitro studies with various vasodilators were performed to evaluate potential intropic effects. Isometric force (cat papillary muscle) increased 2% with 10-4M and 31% with 10-3M HDZ. PZN increased force 4% at 10-6M and 18% at 10-4M. Captopril did not increase force development at any dose level. The doses of HDZ and PZN that increased force development were higher than usual clinical doses.

Adult↗
PubMed1981

Changes in the food intake and body weight of protein-malnourished rats infected with Nippostrongylus brasiliensis (Nematoda).

The daily food intake and related changes in body weight were measured in young rats which were fed on synthetic diets containing 1% (3 experiments), 2% (4 experiments) and 20% (1 experiment) casein respectively. Some rats were infected with Nippostrongylus brasiliensis and allowed to feed ad libitum, some remained uninfected and were allowed to feed ad libitum, while others, which were matched by initial weight with rats from the infected group, remained uninfected and were given only the same amount of food as that consumed during the previous 24 h by their infected partners. No significant differences were detected between the rats before the start of the infection. Thereafter, the food intake of the infected undernourished rats was usually found to be significantly lower and the loss of body weight significantly greater than those of the uninfected rats. In infection periods of relatively long duration, the pair-fed uninfected rats did not lose as much weight as their infected partners even though their food intake (1% and 2% casein) was the same. Although the food intake, and consequently the weight, of infected rats fed on the diet containing 20% casein were significantly less than in their uninfected partners, no significant differences were observed between the weights of the infected and pair-fed rats fed on this diet.

Animals↗
PubMed1981

Aspects of intestinal parasitism in villagers from rural peninsular India.

In 1977, a parasitological survey was undertaken of stool samples collected from 335 people from 5 villages in semi-arid regions of peninsular India. Stools, which were collected from various individuals in a stratified sample of 40 matched households from each village, were examined by standard diagnostic procedures. Eggs of Ascaris lumbricoides and protozoan cysts, which were identified on morphological grounds as belonging to Entamoeba spp., were most common. Other protozoan cysts were considered to be those of Balantidium coli, and eggs of hookworm and Hymenolepis nana were also observed in some of the stool specimens. The prevalence of parasitic infections varied between villages. The village with the highest prevalence of Ascaris (70%) appeared to have the greatest demands made on its meager drinking-water supply. This village is located in a dry, windy and dusty region and it is speculated that, in addition to well-established transmission mechanisms, the villagers may be exposed, perhaps through contamination of uncovered drinking-water wells and inhalation, to wind-borne Ascaris eggs. In 1967, a WHO Expert Committee Report on the Control of Ascariasis pointed out that information on the frequency of dust-borne infection with Ascaris in man was inadequate.

Adolescent↗
PubMed1981

Diastolic aortic root motion in left ventricular hypertrophy.

The echocardiographic motion of the aortic root reflects, in part, left atrial filling and emptying. The echocardiograms of 60 patients with left ventricular hypertrophy (LVH) secondary to aortic stenosis, hypertrophic subaortic stenosis, and hypertension were compared with those of 36 normal subjects to determine whether the alterations of early rapid diastolic filling associated with LvH would alter motion of the posterior aortic root. Patients with LVH had a characteristic echographic pattern of motion of the posterior aortic root manifested by the attenuation of normal abrupt diastolic posterior aortic root motion. The atrial emptying index (AEI), defined as the fraction of passive posterior aortic wall motion occurring in the first third of diastole, was significantly reduced in patients with LVH (p less than 0.001), but did not discriminate among mild, moderate, and marked hypertrophy. The AEI may be useful in the identification of altered left ventricular filling associated with LVH. The changes associated with a decreased AEI are readily appreciated by visual inspection and provide a rapid method of qualitatively assessing left ventricular filling properties.

Adult↗
PubMed1980

Altered prazosin pharmacokinetics in congestive heart failure.

The pharmacokinetics of prazosin (Minipress) were studied in nine patients with NYHA Class 3 or 4 congestive heart failure and in five healthy controls. After a single 5 mg oral dose, plasma concentrations of prazosin, as reflected in the area under the plasma concentration-time curve (AUC) and prazosin plasma half-life, were approximately double in the patients in comparison to the control group. Reduction in hepatic blood flow, altered gastrointestinal absorption of the drug or diminished intrinsic hepatic metabolic activity in the patient group may have contributed to the observed changes in prazosin disposition. The finding of higher prazosin plasma concentrations in patients with refractory heart failure demonstrates the need for close monitoring of these individuals following administration of the drug in the treatment of chronic congestive heart failure.

Adult↗
PubMed1980

Caecal growth in the domestic fowl following surgical manipulation.

1. Some effects of removing increasing proportions of the left caecum on the remaining caecal tissue and on the right caecum were studied in young chicks during a period of 35 d. The chicks were 22 d old when the operations were carried out. 2. No differences were detected between the gains in weight of the control and experimental groups of birds. 3. A marked negative linear relationship was observed between the dry weight of the amount of caecal tissue removed when the birds were 22 d old and weight of the left caecum at the end of the experiment. 4. The average growth rate of the left caecum (g dry tissue/week) was found to be dependent on the estimated weight of caecal tissue remaining after surgery. 5. No evidence was obtained to indicate that the growth of the right caecum responded to the removal of the left caecal tissue. 6. The morphology and histology of the operated caeca were found to be similar to the equivalent regions of the unoperated caeca. Surgical interference was not followed by any major changes in mucosal architecture. 7. In birds which had experienced unilateral caecectomy, the discharge of caecal faeces usually stopped for about 2 d. When caecal defaecation was resumed, the pattern of defaecation appeared to be the same as that observed in sham-operated birds with both caeca intact.

Animals↗