Biomedical subjects

S M Taylor

Publications and source records attributed to S M Taylor.

At least 163 records · Page 9Linked to original sources

PubMed1991

Comparison of arachidonate metabolism by alveolar macrophages from bighorn and domestic sheep.

We have defined the metabolites of arachidonic acid (AA) secreted by alveolar macrophages (AMs) of bighorn sheep and domestic sheep in response to three agents: calcium ionophore A23187, phorbol myristate acetate (PMA), and opsonized zymosan. Cells were labeled with [3H]AA prior to stimulation and 11 tritiated metabolites, including prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and hydroxyeicosatetraenoic acids (HETEs), were detected and quantitated by high-performance liquid chromotography and radiometry. Zymosan stimulation resulted in the release of significantly elevated quantities (P less than 0.05), of LTB4, [5(S), 12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid], 5-HETE, [5(S)-hydroxyeicosatetraenoic acid], and the nonenzymatic isomers of LTB4, [LTB I, 5(S),12(R)-6-trans-LTB4] and LTB II, [5(S), 12(S)-6-trans-LTB4], from domestic sheep AM when compared to bighorn sheep AM. Phorbol myristate acetate (PMA) stimulation released significantly elevated quantities (P less than 0.04), of TXB2, (thromboxane B2), HHT, [12(S)-12-hydroxy-5,8,10-heptadecaenoic acid], LTB I, LTB II, and 15-HETE, [15(S)-hydroxyeicosatetraenoic acid] from domestic sheep AMs when compared to bighorn sheep AMs. However, after A23187 challenge, only 15-HETE was significantly elevated (P less than 0.04) in domestic sheep AMs when compared to bighorn sheep AMs. These clear differences in AA metabolism of AMs obtained from bighorn and domestic sheep in response to three different agonists suggest not only different control mechanisms for lung metabolism of AA in the two species, but also suggest that differences in the metabolites released may lead to quite different regulation of lung defense mechanisms in the two sheep species.

Animals↗

PubMed1991

Results of infrainguinal revascularization with reversed vein conduits: a modern control series.

To determine the outcome of infrainguinal reversed vein bypasses in the modern era, we reviewed the results of 120 consecutive reversed vein grafts performed from March, 1986 to March, 1990. Forty-nine bypasses were to tibial, peroneal, or pedal arteries, 46 grafts to the below-knee popliteal artery, and 25 grafts to the above-knee popliteal artery. Limb salvage was the indication for revascularization in 70% of patients. All grafts were followed with serial, duplex scan, peak-systolic graft flow velocity measurements every three months for one year and every six months thereafter. The primary life table patency rate at 36 months was 67.6% for the entire series; the secondary patency rate was 92.5%. The secondary patency rate reflects the impact of graft revisions resulting from the detection of failing grafts by duplex scanning. Patency rates of reversed vein grafts to the tibial arteries at 36 months (73.8% primary and 89.8% secondary) were equivalent to those performed to the popliteal artery. Our current patency rates with reversed vein grafts are comparable or superior to those reported for in-situ vein conduits and suggest that operative technique and meticulous follow-up are more important with respect to long-term graft durability than whether the vein is used in the in-situ or reversed configuration.

Arterial Occlusive Diseases↗

PubMed1991

The retroperitoneal, left flank approach to the supraceliac aorta for difficult and repeat aortic reconstructions.

Between 1986 and 1990, 11 patients with relative or absolute contraindications to standard infrarenal reconstructions underwent supraceliac aortofemoral bypass. The operation was performed through a left-flank incision extended into the eleventh intercostal space with retroperitoneal and extrapleural dissection. Indications included multiple failed infrarenal reconstructions in four patients, previous removal of infected aortofemoral bypass graft with failure of extra-anatomic bypass in five patients, prior para-aortic lymph node dissection and radiotherapy in one patient, and aortic aneurysmal disease proximal to the renal arteries in one patient. Bypass conduits included either a bifurcated Dacron graft or a tube graft to the left femoral artery with a femorofemoral cross-over graft; concomitant left renal artery reconstruction was performed in three patients. The mean supraceliac cross-clamp time was 24 minutes, and only one patient experienced transient postoperative acute tubular necrosis. There was no operative mortality. The graft limb patency was 95% after mean follow-up extending to 17 months (range: 5 months to 5 years). We conclude that the supraceliac aorta is a useful inflow source for aortofemoral reconstruction in difficult repeat cases. It can be approached easily without thoracotomy and avoids difficult infrarenal aortic dissection in a scarred field. The tunneling is easier than with descending thoracic aorta or ascending aorta inflow sources. In addition, this bypass is likely to be more durable than inflow reconstructions based on the axillary artery.

Aorta, Abdominal↗

PubMed1991

Psychosocial impacts in populations exposed to solid waste facilities.

This interdisciplinary study uses a parallel case study design to investigate psychosocial impacts in populations exposed to three solid waste facilities in Southern Ontario. Impacts are examined at three social scales: individual, social network and community levels. The objectives and design derive from a feasibility study recently completed by the same research team. A two stage approach is adopted. The first is an epidemiologic survey to determine the prevalence of psychosocial impacts in the populations within a prescribed area around each site. A disproportionate stratified (by distance) random sample of 250 households is surveyed at each site. Data on awareness, knowledge, concern and action regarding the site are also obtained. Scores on pre-validated health measurement scales will be compared with population norms to determine the frequency distribution above, within and below the range of normal. The second stage involves the use of qualitative methodologies to provide an in-depth analysis of the individual, social network and community level factors affecting psychosocial impacts and reactions to the situation. Depth interviews with a sub-sample of survey respondents explore individual perceptions, attitudes and actions. Focus groups composed of members of relevant organizations and discussion groups comprising non-members uncover social network and community perspectives in an interactional setting. Interviews and group sessions are taped and transcribed for content analysis of salient themes. Textual analysis of media reports and other relevant documentation provide insights regarding the informational environment and the community context of the issues.

Adaptation, Psychological↗

PubMed1991

The diabetic foot: consequences of delayed treatment and referral.

The pathophysiology of foot problems in diabetic patients is poorly understood by many physicians. Two major factors that frequently lead to a delay in appropriate treatment with subsequent limb loss are failure to appreciate the presence and severity of underlying infection and attribution of gangrene of the toe and forefoot to microvascular disease. To evaluate the consequences of delayed recognition and treatment, we reviewed the records of 55 diabetic patients with localized gangrene or infection of the forefoot in 62 limbs, treated consecutively on a single vascular surgical service over a 2-year period using a standard protocol. All appropriately treated neuropathic ulcers and forefoot infections healed in patients with palpable pedal pulses. If foot pulses were absent and arteriography confirmed large-vessel occlusive disease, foot lesions and infections likewise healed if concomitant revascularization was done. In our series, 33 bypasses were required because of severe atherosclerotic occlusive disease. Only one patient had "unreconstructable" arterial disease. Limb salvage was 86% at a mean follow-up of 12.4 months. In 16 of the patients (29%), there was a prolonged delay between initial treatment and referral for definitive care. The specific causes of delay were underestimation of the severity of foot infection in 10 patients, and lack of recognition of ischemia due to large-vessel occlusive disease in six. These delays led to more proximal levels of amputation in six patients, including three below-knee amputations in patients with limbs that were initially salvageable.

Adult↗

PubMed1991

Clearance and disposition of ritodrine in the fluid compartments of the fetal lamb during and after constant rate fetal intravenous infusion.

The disposition of the beta-2 adrenoreceptor agonist, ritodrine, has been examined in the fetal lamb during and after constant rate fetal intravenous infusion (8-24 h). Samples were collected from the fetal femoral artery, umbilical vein, maternal femoral artery, uterine vein, fetal trachea and the amniotic activity for ritodrine quantitation. The amniotic fluid was also analyzed for conjugated metabolites of ritodrine. Ritodrine appears to be cleared across the sheep placenta only to a limited extent (placental clearance 9.2 +/- 2 ml/min/kg; mean +/- S.E.M.). There is, however, significant fetal nonplacental clearance of ritodrine (fetal nonplacental clearance 52.8 +/- 8.0 ml/min/kg). At least part of this clearance appears to be due to fetal drug metabolism, as evidenced by the accumulation of glucuronide conjugates of ritodrine in the amniotic fluid. Ritodrine was also shown to accumulate in the amniotic and fetal tracheal fluids and persist after fetal arterial plasma ritodrine concentrations became undetectable. The accumulation of ritodrine in the tracheal fluid may be of pharmacologic significance, given the well documented, potent effects of beta-2 agonists on fetal lung function and development.

Animals↗

PubMed1991

Duodenal stricture: a complication of chronic fibrocalcific pancreatitis.

Over the past 10 years, one of us (M.C.A.) has treated 92 patients who required operation for symptoms associated with alcohol-induced chronic fibrocalcific pancreatitis. Four of these patients had duodenal obstruction. All four had had lateral pancreaticojejunostomy to relieve pancreatic ductal obstruction and associated chronic abdominal pain; three of the four also required biliary diversion for stenosis of the intrapancreatic portion of the common bile duct. Each duodenal stricture required reoperation and gastrojejunostomy to bypass the site of obstruction. A review of the English language literature revealed that duodenal obstruction in patients with chronic fibrocalcific pancreatitis is uncommon, only 58 previous cases having been reported. All of those patients had pancreatic ductal obstruction, and more than half had concomitant distal biliary stenosis. Two thirds of the duodenal obstructions were treated by gastroenterostomy, and one third were resected. Duodenal obstruction in patients with chronic pancreatitis and biliary stricture appears to reflect an advanced form of the disease. Combined lateral pancreaticojejunostomy and biliary diversion has emerged as the preferred surgical procedure for this problem. Careful preoperative assessment for evidence of duodenal stenosis also is needed in this group of patients, and gastroenterostomy is indicated in appropriate cases.

Adult↗

PubMed1990

Comparison of the efficacy of dermal formulations of ivermectin and levamisole for the treatment and prevention of Dictyocaulus viviparus infection in cattle.

Four groups of six parasite-naive calves were infected at seven day intervals with three doses of infective larvae of Dictyocaulus viviparus. Twenty-one days after the first dose three of the groups were treated either with an injectable formulation of ivermectin at a dose rate of 200 micrograms/kg bodyweight, or with pour-on preparations of levamisole at 10 mg/kg or ivermectin at 500 micrograms/kg. On day 28 two calves from each group were slaughtered and their burdens of lungworms counted. On day 35 the remaining calves were reinfected with D viviparus infective larvae at a rate of 80 L3/kg. The levamisole preparation was 94.6 per cent effective and both ivermectin preparations were 100 per cent effective against the initial infections. The ivermectin-treated calves were protected from the reinfection which subsequently became patent in the levamisole-treated and control calves.

Administration, Topical↗

PubMed1990

A comparison of interactions between vaccination against Dictyocaulus viviparus and anthelmintic suppression in immunised and unimmunised yearling cattle.

Twenty parasite-naive calves aged approximately four months were divided randomly into four groups of five. Two groups were treated with oral lungworm vaccine. One immunised group plus another non-immunised group were put out to graze on May 1 on a pasture known to be contaminated with Dictyocaulus viviparus infective larvae during the previous autumn. All the calves both indoor and outdoor were treated with ivermectin at three, eight and 13 weeks after the first groups started to graze and again at housing at the end of September. After the winter housing period on April 27 of the following year all the calves were given an artificial challenge of D viviparus infective larvae at the rate of 15 larvae per kg bodyweight, and the clinical and parasitological reactions monitored. All the calves which had been vaccinated or exposed to field infection during year 1 reacted strongly in ELISAs using antigen prepared from fourth stage D viviparus larvae but much less strongly in similar tests using adult derived antigen. Clinically those calves exposed to previous field infections were less severely affected than the housed calves, although parasitologically all three groups with prior exposure to D viviparus appeared to have a similar functional level of immunity to the challenge infection in comparison to the unexposed calves of the same age.

Animals↗

PubMed1990

Functional studies of bovine alveolar neutrophils elicited with recombinant bovine IL-1 beta.

Bovine rIL-1 beta (rbIL-1 beta) was instilled intrabronchially into the lungs of steers to elicit harvestable alveolar neutrophils for functional analysis. Before instillation, bronchoalveolar lavage samples from the steers consisted of 96.4 +/- 1.5% (mean +/- SEM) macrophages, with the remaining cells neutrophils and occasional lymphocytes. Four hours after instillation of 1.0 and 10.0 nmol of IL-1, the lavage samples consisted of 96.3 +/- 0.8% and 91.0 +/- 5.7% neutrophils, respectively. Alveolar neutrophils elicited with rbIL-1 beta and challenged with the calcium ionophore, A23187, released similar amounts of leukotriene B4 (LTB4) and its nonenzymatic isomer LTB I, and significantly greater amounts of 5-hydroxyeicosatetraenoic acid and the nonenzymatic isomer LTB II, when compared with circulating neutrophils. The rbIL-1 beta did not, by itself, stimulate release of arachidonate metabolites from circulating neutrophils in quantities that were detectable by HPLC. Circulating neutrophils, preincubated with rbIL-1 beta and stimulated with A23187, released significantly greater amounts of 5-hydroxyeicosatetraenoic acid and total 5-lipoxygenase metabolites when compared with control cells not incubated with rbIL-1 beta. Incubation of circulating neutrophils with rbIL-1 beta and A23187 concurrently resulted in a significantly increased release of all 5-lipoxygenase metabolites of arachidonate. However, both the release of superoxide anion and bacterial killing by rbIL-1 beta-elicited bovine alveolar neutrophils did not differ from the values obtained for circulating neutrophils.

Animals↗

PubMed1990

Influence of extracellular calcium on the metabolism of arachidonic acid in alveolar macrophages.

Bovine alveolar macrophage metabolism of arachidonic acid (AA) via cyclooxygenase (CO) and lipoxygenase (LO) pathways is stimulus specific. Under standard conditions with RPMI-1640 media containing 0.4 mM Ca2+, the calcium ionophore A23187 stimulates the release of both CO and LO products, whereas opsonized zymosan and phorbol myristate acetate (PMA) selectively stimulate the CO pathway in these cells. We have examined the effect of varying the extracellular concentration of calcium (0-2.4 mM) on the profiles of AA metabolites secreted with differing stimuli. All stimuli caused the release of CO products, even in the absence of calcium in the media. The magnitude of release was correlated with increasing extracellular calcium concentrations, indicating some dependence of phospholipase activation on extracellular calcium. However, there were notable differences between stimuli regarding the magnitude of CO product formation and dependence on extracellular Ca2+. No 5-LO products were demonstrable with either zymosan or PMA at any concentration of extracellular calcium tested, and inhibition of CO by indomethacin did not result in 5-LO product formation for these stimuli. The production of 5-LO products in bovine alveolar macrophages by A23187 required extracellular calcium, demonstrating an absolute dependence for activation of the 5-LO pathway on an influx of extracellular calcium. Our results indicate that intracellular and extracellular Ca2+ have differing roles in the metabolism of AA down CO and LO pathways in bovine alveolar macrophages depending on the stimulus used. This regulation suggests that the pools of calcium required for activation of phospholipase A2 (PLA2) are not necessarily available for the 5-LO enzyme.

Animals↗

PubMed1990

Fetal and maternal placental and nonplacental clearances of metoclopramide in chronically instrumented pregnant sheep.

The placental and nonplacental clearances of metoclopramide were studied in nine chronically instrumented, near-term pregnant sheep using a two-compartment open model. Metoclopramide was administered to the ewe and fetus on separate occasions as an initial iv bolus loading dose followed by a constant-rate infusion, with steady-state maternal and fetal plasma concentrations being obtained by 45 min. Following the maternal infusions, metoclopramide reached average steady-state concentrations of 50.0 +/- 20.2 ng/mL in the ewe and 27.1 +/- 8.6 ng/mL in the fetus, with a mean fetal-to-maternal concentration ratio of 0.57 +/- 0.14. The ability of the fetus to eliminate metoclopramide by nonplacental routes appears to be responsible for this ratio being less than unity, rather than differential protein binding and ion-trapping effects. Mean steady-state concentrations were 13.8 +/- 4.5 and 253.7 +/- 92.1 ng/mL in the ewe and fetus, respectively, after fetal drug administration. Metoclopramide was bound significantly less to fetal (39.5 +/- 8.9%) than to maternal (49.5 +/- 7.9%) plasma proteins, with values similar to that reported for humans (approximately 40%). Clearance of metoclopramide across the placenta from the fetus to the ewe (6.2 +/- 2.4 L/h/kg) was significantly greater than that in the reverse direction (4.3 +/- 1.3 L/h/kg) and accounted for approximately 80% of total fetal drug elimination. This may be explained by the higher percentage of fetal cardiac output to the placenta and the flow-limited transfer of this compound.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Production of arachidonic acid metabolites by caprine alveolar macrophages.

The in vitro release of arachidonic acid (AA) metabolites from caprine alveolar macrophages (CAM) stimulated with the calcium ionophore A23187 or opsonized zymosan was examined. Leukotriene B4 [5(S),12(R)-6,14-cis-8,10-trans-dihydroxyeicosatetraenoic acid] was the major AA metabolite elicited with either agonist; smaller amounts of 12- and 5-mono-hydroxyeicosatetraenoic acid (HETE), and 12-hydroxyheptadecatrienoic acid (HHT) were also detected. Zymosan stimulation also caused the release of very small quantities of prostaglandins E2 and F2 alpha, and thromboxane B2. Our report is the first to describe arachidonic acid metabolism in CAM.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1990

Reported versus recorded health service utilization in Grenada, West Indies.

Calls for household surveys to provide information on service utilization in less developed countries raise questions regarding the accuracy and reliability of reporting. This paper compares reported to recorded health service utilization for diarrhoea and any other morbidity over a 2-week and 3-month period for information obtained from a household survey in Grenada, West Indies. A sensitivity analysis is used to derive minimum and maximum estimates of the accuracy of reported utilization. Over-reporting utilization was found to be between 33 and 62% for diarrhoea and 49 and 81% for any other morbidity. Under-reporting of all utilization was estimated to be between 47 and 65%. These results cast doubt on the utility of household surveys as a reliable source of information regarding service utilization.

Child↗

PubMed1990

The risk approach in diarrheal disease intervention in Grenada.

In a previous paper (Soc. Sci. Med. 23, 995-1002, 1986), we described the development of a method for identifying households at high risk of childhood diarrhea based on a logit analysis of data collected as part of a diarrhea disease control project in Grenada. In this paper, we report the results of a follow-up study designed to replicate the first using data on diarrhea incidence and risk factors collected in a different set of rural communities in Grenada. The findings of the first study were not replicated. There was no significant association between the risk factors and diarrhea in the follow-up study in contrast to the very strong associations found in the first study. As a consequence, it was not possible to construct a logit model from the second data set. The possible reasons for the contrasting sets of results and their implications for the application of the risk approach are discussed with reference to a two by two true-false table.

Diarrhea↗

PubMed1990

The ecology of health services utilization in Grenada, West Indies.

Few empirical investigations into the nature of health services utilization fully acknowledge that the home environment may act as a socio-geographic focus of both disease transmission and of learned health behavior. This paper examines the role of the home environment, as well as of personal characteristics and accessibility, in the utilization of health services in Grenada, West Indies. Bivariate and logit analyses of household survey data are employed to identify markers of high user individuals and households. Aspects of each domain of the home environment (physical and behavioral environment, demographics, and residential mobility) emerge as contributors to the utilization phenomenon in the study communities. Both etiological and socio-economic linkages are postulated to underlie the observed relationships. The implications of this work for health planning in developing countries is discussed.

Age Factors↗

PubMed1990

Housing satisfaction, preference and need among the chronically mentally disabled in Hamilton, Ontario.

This paper examines housing satisfaction, preference and need among a sample of the CMD in Hamilton, Ontario. The research goes beyond simply documenting the gap in housing supply by examining issues of housing quality as expressed by clients themselves. Survey data were obtained in two rounds of interviews from 66 clients attached to three aftercare programmes. Various indicators were consistent in showing a relatively high level of satisfaction with the current living situation. At the same time, clients reported major housing difficulties due to lack of appropriate and affordable accommodation, unacceptable conditions and financial constraints. Housing satisfaction was a significant correlate of scores of coping indices. There was considerable variability in satisfaction within groups of the sample defined in terms of type of housing, location and living arrangement. Data on preferences and expressed needs correspond quite closely with normative prescriptions for a continuum of housing options ranging from restricted congregate care to autonomous individual living situations. These findings underline the heterogeneity of the CMD and their needs.

Adaptation, Psychological↗

PubMed1990

Methylmalonyl-CoA mutase (EC 5.4.99.2) and methionine synthetase (EC 2.1.1.13) in the tissues of cobalt-vitamin B12 deficient sheep.

The changes in the activities of the two vitamin B12-dependent enzymes methylmalonyl-CoA mutase (EC 5.4.99.2) and methionine synthetase (5-methyltetrahydrofolate-homocysteine methyltransferase, EC 2.1.1.13) are described in two groups of sheep maintained for 20 weeks on either a cobalt-deficient or a Co-sufficient whole-barley diet. At the end of that period, the plasma concentrations of vitamin B12 were depressed and those of methylmalonic acid were raised in the Co-deficient group. During the course of the experiment hepatic holo-mutase activity, measured on biopsy samples, declined in Co-deficient animals with a half-life of 73 d. There was a similar, but slower decline in lymphocyte holo-mutase activity which fell with a half-life of 125 d. At slaughter, there was no difference between Co-sufficient and Co-deficient animals in total mutase activity in liver, kidney, brain and spinal cord. In contrast, the total-synthetase activity of liver and kidney was reduced by 60 and 30% respectively in the Co-deficient animals. There was no change in either group of animals in total-synthetase activity, or in either holo-mutase or holo-synthetase activity, in brain and spinal cord. In the Co-deficient animals, holo-mutase and holo-synthetase activities in liver, the tissue with the greatest activity of both enzymes, fell to 25 and 39% respectively, of that of Co-sufficient animals. The corresponding reductions for kidney were 12 and 51% respectively. These results indicated that activity of both holoenzymes is greatly reduced in Co-deficient sheep.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗