Search PubMed⌕ Search

Biomedical subjects

H J Smith

Publications and source records attributed to H J Smith.

At least 145 records · Page 8Linked to original sources
PubMed1988

Effects of chronic sympathectomy on muscle fibre composition ISO-myosin patterns, protein synthesis and calcium content in canine gracilis muscle.

We have previously reported functional and histological studies in five beagle dogs with unilateral lumbar sympathectomy. Three months later, fatiguability in the gracilis muscles was increased on the denervated sides, and this was associated with an increase in the relative distribution of FT fibres. Biochemical studies now show that these changes were associated with an increase in cytosolic protein without change in DNA content; this is consistent with an increase in cell size. There was a reduction in the proportion of slow myosin light chain isoforms from 50 +/- 7 to 34 +/- 6%. Noradrenaline levels were increased on the denervated sides but this may reflect greater vascularity. Calcium content did not correlate with fibre type but there was a positive relation with both noradrenaline content (r = 0.73; P less than 0.05) and DNA content (r = 0.84; P less than 0.05). It is concluded that sympathectomy induces several biochemical changes in skeletal muscle which constitute a change and increase in fast myosin light chain synthesis and a corresponding fibre type transformation.

Animals↗
PubMed1988

Isolation of Mobiluncus species from clinical specimens by using cold enrichment and selective media.

New and selective Rlk and SA media, combined with cold enrichment at 4 to 5 degrees C, allowed isolation of Mobiluncus species from patients with bacterial vaginosis at higher rates than with conventional cultivation methods. Rlk medium consists of Columbia CNA agar supplemented with peptone, yeast extract, 5% laked rabbit or sheep blood, nalidixic acid, and tinidazole. SA medium consists of Columbia CNA agar supplemented with 2% rabbit serum, 1.6% laked rabbit or sheep blood, nalidixic acid, and tinidazole. Use of these selective media plus the cold enrichment technique permitted Mobiluncus species to propagate at rates similar to those of other anaerobic members of the vaginal flora.

Bacteria, Anaerobic↗
PubMed1988

Risk of hepatitis B infection among medical and paramedical workers in a general hospital in Zimbabwe.

To evaluate the addition of hepatitis vaccine to health schemes for hospital workers in Zimbabwe we undertook a cross sectional study of viral markers in 226 hospital workers and compared the results with 97 volunteer blood donor controls. One hundred and thirty one (58%) hospital workers had hepatitis markers compared with 45 (46%) of the donor group. Racial group was the strongest risk factor. Blacks were 70% more likely to have markers than whites. This racial difference was not explained by job status or patient contact. Our data suggest that work in a district general hospital does not constitute a clinically important hazard for hepatitis B infection. Because of the high cost of the vaccine, additional studies to assess the risk of hospital work in other settings in Zimbabwe are required before health policy regarding routine hepatitis B vaccination is determined.

Black or African American↗
PubMed1988

Pooling of sera for human immunodeficiency virus (HIV) testing: an economical method for use in developing countries.

To determine whether donated blood samples in African countries could be pooled, then tested for the presence of human immunodeficiency virus (HIV) antibodies with a single test without loss of accuracy, a single test on five pooled samples was used, followed by individual testing of positive pools. This resulted in no loss of either sensitivity or specificity. Pooling 10 samples resulted in a loss of sensitivity for low antibody titre specimens. Pooling reduced the costs of screening by 70% and time needed for analysis. It is concluded that pooling of five samples for HIV screening may result in a substantial reduction in costs; in countries where the prevalence of HIV is higher than the 2-3% found in Zimbabwean donors, however, savings may not be as great.

Acquired Immunodeficiency Syndrome↗
PubMed1988

MR imaging in the management of supratentorial intracranial AVMs.

The MR images, CT scans, and angiograms of 15 consecutive patients with intracranial, supratentorial arteriovenous malformations (AVMs) were studied retrospectively. The three imaging techniques were evaluated separately to assess their utility in defining the size, characteristics, and location of the AVM nidus, its arterial supply, and venous drainage. The studies were also evaluated for their ability to show associated parenchymal abnormalities, the presence of mass effect, and changes occurring after embolization. MR was superior to both CT and angiography in showing the exact anatomic relationships of the nidus, feeding arteries, and draining veins, as well as in demonstrating the extent of AVM nidus obliteration after embolization. MR was more sensitive than CT in revealing associated parenchymal abnormalities and subacute hemorrhage. Because of flow-related artifacts and low sensitivity in distinguishing calcification from rapid flow and/or hemosiderin, MR seemed to have a low sensitivity for detecting old hemorrhage within an AVM nidus. Angiography is still needed in the planning of either surgical or endovascular treatment of AVMs.

Adolescent↗
PubMed1988

Comparison of pepsin-digestion and enzyme-linked immunosorbent assay for the diagnosis of trichinosis in swine.

Comparison of parasitological and serological diagnosis of trichinosis in swine was carried out on 36 pigs given 15,400 infective larvae each by gavage. Circulating eosinophil levels were determined and sera were examined by enzyme-linked immunosorbent assay for anti-Trichinella antibodies. Two pigs were killed per day from days 15 to 29 postinfection. Muscle was examined by pepsin-digestion and comparable tissue was fed to a rat. Eosinophil counts increased at about day 6 and reached peak levels about day 25 postinfection and returned to approximate preinfection levels about two months postinfection in those pigs still in the study. Infective larvae were recovered from all pigs killed at greater than or equal to 18 days postinfection. Using the criterion of 5 x mean optical density readings of negative sera as positive, seroconversion occurred between days 19 and 26 postinfection. Use of a lower criterion of 3 x mean optical density readings of negative sera resulted in only three of 30 pigs killed greater than or equal to 18 days postinfection seroconverting less than or equal to 18 days postinfection, when infective larvae were first recovered in the musculature. In pigs, even in those heavily infected, there is a lag between the period that trichinae in musculature become infective and development of antibodies as detected by enzyme-linked immunosorbent assay which results in false negative reactions in many animals. This study demonstrated that the enzyme-linked immunosorbent assay using an excretory-secretory antigen should not be used to certify pork or pork products free of infective Trichinella larvae or safe for human consumption.

Animals↗
PubMed1988

Prevalence of trichinosis in Canadian swine determined serologically by enzyme-linked immunosorbent assay.

Fifteen thousand three hundred and eighteen porcine sera from all regions of Canada were examined for the presence of anti-Trichinella antibodies using the enzyme-linked immunosorbent assay with an excretory-secretory antigen. Four sera (0.026%) revealed the presence of anti-Trichinella antibodies, with titers (optical density readings) that fell in the low positive or high negative range on repeated examinations. One animal originated in British Columbia and three in Ontario. Serological examination of swine in the herds at time of traceback did not reveal further animals with anti-Trichinella antibodies.

Animals↗
PubMed1988

Sylvatic trichinosis in Canada.

Pepsin digestion of musculature from 2253 animals revealed that sylvatic trichinosis occurred in various species of mammals from the eastern to the western Arctic and extended down into the Rocky Mountain and Foothills regions of western Canada. Infections were demonstrated in Arctic fox, red fox, wolf, raccoon, coyote, lynx, bobcat and dog.

Animals↗
PubMed1987

Effect of cisapride on gastric emptying of indigestible solids in patients with gastroparesis diabeticorum. A comparison with metoclopramide and placebo.

Cisapride is a prokinetic agent believed to facilitate acetylcholine release from the myenteric plexus of the gut. The effect of cisapride on gastric emptying of solids was studied in 9 diabetic patients, all of whom had delayed gastric emptying of indigestible solids (gastroparesis). Six patients had chronic nausea and vomiting, and 3 had no symptoms. Cisapride (5 mg) was given intravenously 15 min before ingestion of a 400-kcal test meal and 10 indigestible solid radiopaque markers. On separate days and in random order each patient also received intravenous metoclopramide (10 mg) or placebo 15 min before ingestion of the meal and markers. Mean gastric emptying of radiopaque markers, assessed by serial radiographs of the gastric region, was accelerated by metoclopramide and cisapride, but the difference reached significance only with cisapride (p less than 0.05). There was considerable intersubject variability in gastric emptying responses to cisapride and metoclopramide. No side effects occurred with either drug. This study indicates that acute, intravenous administration of cisapride accelerates gastric emptying of indigestible solids in patients with diabetic gastroparesis.

Adult↗
PubMed1987

Inhibition of aromatase activity in the rat by aminoglutethimide and related compounds.

Two compounds possessing aromatase inhibitory activity have been evaluated for their effects on oestradiol (E2) biosynthesis in the rat. These compounds, structurally related to aminoglutethimide (1), were administered intra-peritoneally at two dose levels to 10 week old female rats previously treated with pregnant mares' serum gonadotrophin (PMSG, 100 i.u. subcutaneously every other day for 9 days). Three hours after dosing, blood was collected and plasma oestradiol levels determined by RIA. Aminoglutethimide, 3-(4'-aminophenyl-3-ethylpyrrolidine-2,5-dione (2) and N-methyl-3-(4'-aminophenyl)-3-ethylpyrrolidine-2,5-dione (3) decreased E2 blood levels by 98, 97 and 82% of control levels respectively (n = 6) at a dose of 50 mg/kg. Similarly effective inhibition was also observed at a dose of 25 mg/kg (n = 4). Ovarian aromatase activity, assessed by incubating the homogenised ovaries of treated rats with tritium-labelled androstenedione (0.2 microM) or testosterone (1 microM), indicated that residual enzyme activity was reduced compared with controls. Aminoglutethimide, and the new pyrrolidinedione aromatase inhibitors 2 and 3, are therefore effective inhibitors of E2 biosynthesis in the rat with functioning ovarian activity.

Aminoglutethimide↗
PubMed1987

Effects of beta-adrenoceptor blockade on heart rate and physiological tremor in diabetics with autonomic neuropathy. A comparative study of epanolol, atenolol and pindolol.

Eight diabetics with autonomic neuropathy were given single oral doses of epanolol (200 mg), atenolol (50 mg), pindolol (5 mg) and placebo in a double-blind randomised order at weekly intervals. Supine resting heart rate, physiological tremor and blood glucose were measured before, 2 and 4 h after dosing, and ambulatory heart rate monitored for 24 h. Supine resting heart rate was significantly lowered by atenolol both at 2 and 4 h, and increased on pindolol at 4 h. Heart rate was unaffected by epanolol compared with placebo. Heart rate during the 'waking' period (14.00-23.00 h) was lower than placebo after epanolol and atenolol but unaffected by pindolol. During the 'sleeping' period (23.00 h-08.00 h) heart rate was significantly increased by pindolol, lowered with atenolol and unaffected on epanolol. Pindolol significantly increased physiological tremor at 4 h. No differences were seen between epanolol, atenolol and placebo. Plasma glucose was significantly increased by pindolol 2 h after dosing. These results suggest that pindolol probably produces its partial agonist activity at both beta 1- and beta 2-adrenoceptors, while the partial agonist activity of epanolol is beta 1-selective. Despite abnormal cardiovascular reflex tests in these diabetics, the heart rate responses obtained in this study after beta-adrenoceptor blockade were surprisingly normal, and suggest that the concept of 'cardiac denervation' in diabetes requires modification.

Adrenergic beta-Antagonists↗
PubMed1987

Right ventricular blood temperature profiles for rate responsive pacing.

To establish the efficacy of a temperature-based pacemaker control algorithm, right ventricular temperature and heart rate were measured for 12-70 hours in eight patients (51 +/- 17 years) and in one normal volunteer (28 years) during a variety of activities including exercise, rest, sleeping, eating, drinking, and bathing. A diurnal variation in heart rate and temperature was observed. Drinking caused transient temperature changes (less than one minute); during eating, increases of 0.07-0.36 degrees C over 3-12 minutes were observed. An increase of 0.24 degrees C over 8.5 minutes was observed in one patient during bathing. An abrupt drop in temperature was typically observed at the onset of exercise, followed by a steady temperature rise. During treadmill exercise, after a drop (0.13-0.48 degrees C, Bruce n = 4; 0.16-0.34 degrees C, Naughton, n = 3) during the first 1-2 minutes, temperature rose steadily through the end of peak exercise (0.45-1.01 degrees C, Bruce; 0.28-0.47 degrees C, Naughton). A temperature dip was also observed when a patient was told exercise would start but the treadmill failed to turn on. The dip is probably secondary to changes in blood flow from the peripheral circulation to the central system at the onset of exercise. Repeated exercise separated by short rests caused progressive blunting of the initial dip. Right ventricular temperature changes in a predictable manner with daily activity, allowing a temperature algorithm to detect rest and exercise.

Adult↗
PubMed1987

Performance of barium examinations after acute myocardial infarction: report of a survey.

A survey of members of the Society of Gastrointestinal Radiologists was conducted to ascertain the standards of practice and timing for elective barium studies of the gastrointestinal tract in patients recovering from acute myocardial infarction. Sixty-two percent of respondents do not have cardiac monitoring apparatus readily available in the fluoroscopy suite. When readily available, such equipment is rarely (42%) or never (58%) used during routine barium examinations. Twenty-four percent of respondents take special precautions when performing examinations on these patients by reducing patient movement, the length of the examination, and the number of radiographs exposed, and by employing cardiac monitoring. Seventy-two (89%) of 81 respondents noted at least one adverse cardiovascular reaction. This was most often chest pain, but there were 10 deaths from cardiac causes. Two-thirds of respondents delay elective barium examinations of any kind for at least 4 weeks after acute myocardial infarction. The remaining one-third perform these studies earlier than 4 weeks. The latter typically limit their studies to the upper gastrointestinal tract (82%), 42% of which are single-contrast; the rest are equally divided between double-contrast and biphasic studies. This minority of radiologists is twice as likely to perform a single-contrast barium enema than a double-contrast barium enema during this period. No such preference for single-contrast (47%) over double-contrast (53%) barium enema is revealed by the majority who delay their elective barium enemas 4 or more weeks. The data indicate a strong preference to defer elective barium examinations a minimum of 4 weeks after acute myocardial infarction. A sizable minority (one-third) of radiologists, however, feel comfortable performing a single-contrast upper gastrointestinal examination at an earlier time.

Barium Sulfate↗
PubMed1987

Factors affecting preconditioning of Trichinella spiralis nativa larvae in musculature to low temperatures.

The influence of preconditioning temperature, length of the preconditioning period, host and age of the infection on the survival of Trichinella spiralis nativa larvae in musculature to low temperature refrigeration was investigated. Dogs, foxes, ferrets, mink and guinea pigs were infected with a T. spiralis nativa isolate, killed at various times postinfection, preconditioned at temperature of -10 degrees C, -15 degrees C or -20 degrees C for varying periods of time prior to low temperature refrigeration and subsequent pepsin digestion to determine survival of larvae. The preconditioning temperature played an important role in the subsequent survival of larvae in musculature at low refrigeration temperatures. Under the conditions of this study, survival of larvae was greater as the preconditioning temperature became lower. The minimum period of preconditioning required had an inverse relationship with the refrigeration temperature. Preconditioning of the T. spiralis nativa isolate used occurred in the musculature of guinea pigs, foxes, ferrets, mink and dogs with larvae surviving longer in vulpine and canine musculature than in the other hosts studied. Age of the infection was not a major factor in the survival of preconditioned larvae in musculature at low refrigeration temperatures although survival was slightly longer in older infections.

Animals↗
PubMed1987

Evaluation of the ELISA for the serological diagnosis of trichinosis in Canadian swine.

An ELISA using a Trichinella spiralis spiralis excretory-secretory antigen was evaluated as a procedure for the diagnosis of trichinosis in swine in Canada. Field and experimental trials were carried out using both indirect serological (ELISA) and direct parasitological (pepsin-digestion) methods concurrently on serum and musculature, respectively, from each animal. The ELISA is a sensitive and specific test for the detection of Trichinella antibodies in porcine sera when present. The development of Trichinella antibodies appears to be dependent on the magnitude of the infection established, age of the infection when the animal is tested and the immunocompetence or response to infection of individual animals. False negative reactions were recorded in both field and experimental trials. In the field study, five of the 1009 swine examined were parasitologically positive with light infections ranging from 0.01 to 0.046 larvae per gram (la/g) of musculature yet all were serologically negative. Experimentally it was shown that Trichinella antibodies develop slowly, at least two to three months postinfection, in pigs with very light infections. Even in pigs which developed infections of 33 to 55 la/g of musculature, seroconversion occurred greater than 23 and less than 30 days postinfection. The immunocompetence or response to infection of individual pigs was variable as illustrated by one pig inoculated with 3000 infective larvae which had consistently lower titers compared to others in the same group despite the establishment of a muscle infection of 8.5 la/g of musculature. One false positive reaction was recorded in the experimental trial in an animal which had received 100 larvae and seroconverted at about three months postinfection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Vaccination of rats and pigs against Trichinella spiralis spiralis using the subspecies, T. spiralis nativa.

Rats and pigs were vaccinated against Trichinella spiralis spiralis either by feeding infective larvae of the subspecies, Trichinella spiralis nativa in musculature or by gavage. The number of larvae established in the musculature of vaccinated nonchallenged and vaccinated challenged rats and pigs were negligible and statistically comparable, while highly significant infections were established in the nonvaccinated challenged rats and pigs. High vaccination doses of T. spiralis nativa gave virtually complete protection to challenge with T. spiralis spiralis in pigs. The results of one trial in rats with a lower vaccination dose of larvae suggest that there is a minimal vaccination dose of larvae required to elicit marked resistance to challenge. The low numbers of muscle larvae established due to the high vaccination doses of larvae confirm the low infectivity of the subspecies, T. spiralis nativa in rats and pigs.

Animals↗
PubMed1987

Detection of Trichinella spiralis nativa antibodies in porcine sera by ELISA using T. spiralis spiralis excretory-secretory antigen.

Enzyme-linked immunosorbent assay examination of sera from pigs vaccinated with T. spiralis nativa infective larvae and/or challenged with T. spiralis spiralis larvae using a T. spiralis spiralis excretory-secretory antigen showed a significant cross-reaction between the two species of Trichinella. Eight of 12 pigs vaccinated with a high dose of T. spiralis nativa reacted positively 28 days postvaccination while the remaining four pigs had high but negative ELISA optical density readings. Five of six pigs challenged with the homologous species reacted positively 28 days postchallenge but the sixth pig remained negative despite having a muscle infection of 5.6 larvae/g of musculature.

Animals↗