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Biomedical subjects

S M Taylor

Publications and source records attributed to S M Taylor.

At least 109 records · Page 6Linked to original sources
PubMed1995

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) second edition of guidelines for evaluating the efficacy of anthelmintics in ruminants (bovine, ovine, caprine)

The first edition of the W.A.A.V.P. anthelmintic guidelines for ruminants was published in 1982. Since then improved parasitological procedures have been developed, new therapeutic and prophylactic products have appeared requiring different test methods, and registration authorities are requesting more detailed record keeping and data validation. This second edition addresses these developments and fulfills the original goal of publishing guidelines for high quality, scientifically valid testing standards for trials that would be accepted as proof of efficacy by registration authorities regardless of country of origin. This second edition includes updated guidance on standard parasitological procedures, dose titration, dose confirmation and clinical trials, and provides guidelines for evaluating products for efficacy against anthelmintic resistant parasites, persistence of activity and prophylactic activity. Tests for efficacy against nematodes, trematodes and cestodes are included.

Animals↗
PubMed1995

Airway smooth muscle proliferation in asthma: the potential of vascular leakage to contribute to pathogenesis.

Proliferation of the non-vascular smooth muscle in the walls of the bronchi and bronchioles is a prominent histopathological feature of asthma and is thought to contribute to airway hyperreactivity and narrowing. Increased vascular permeability with plasma leakage is also a feature of asthma pathology and causes submucosal oedema. We hypothesize that, in asthmatics, the accumulation of enriched plasma in the environment surrounding airway smooth muscle promotes respiratory smooth muscle mitogenesis and hyperplasia. This situation represents the in vivo correlate of the increase in airway smooth muscle cell growth seen in vitro with increasing concentrations of serum in the culture medium. Thus, we hypothesize that vascular leakage in the airways in asthma is a primary pathogenic event leading to airway smooth muscle hyperplasia and hypertrophy, and consequently airway narrowing, promoting the characteristic bronchial hyperreactivity associated with narrowing of the airway lumen.

Animals↗
PubMed1995

The effect of C5a and U46619 on the isolated, perfused human placental lobule: development of a method for the online estimation of tissue fluid accumulation.

A method for the automatic and simultaneous determination of perfusion pressure and fluid accumulation in the isolated, perfused human placental lobule is described. We demonstrated that the inflammatory mediator, C5a, a C5a agonist analogue peptide, and the thromboxane mimetic U46619 caused increased fetal perfusion pressure and increased tissue weight when administered via the fetal arterial circulation. Occlusion of the fetal venous effluent tubing caused significantly greater increases in tissue weight than the pharmacological agents. Detectable increases in tissue weight occurred within 47 +/- 3 sec (n = 21) following pressure increases caused by the pharmacological agents. In each case, the increase in tissue weight was accompanied by an increased permeability of the materno-fetal barrier, shown by the transfer of Evans blue albumin from the fetal circulation to the maternal compartment.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1995

Blood volume restitution and growth in fetal lambs after acute hemorrhage.

The effects of 15-50% fetal hemorrhage (at approximately 1%/min) were studied in 13 pregnant ewes at 130-135 days of gestation for up to 5 days posthemorrhage. The upper limit of acute blood loss appears to be approximately 45%, and the rate of restoration of blood volume decreases with the severity of hemorrhage, particularly with hemorrhage > 30-40%. The restoration of fetal blood volume was due primarily to the restoration of plasma volume; in the animals subject to 40-45% blood loss (n = 9), red cell mass was still only 69.1 +/- 3.9% of the prehemorrhage value at day 5 posthemorrhage. There appear to be two phases in the restoration of plasma: 1) plasma volume was restored by 2 h posthemorrhage and 2) the restoration of plasma protein mass occurred primarily from 2 to 24 h. There was a significant correlation between blood volume and plasma protein mass. However, the regression line for the posthemorrhage days was shifted significantly upward in relation to that for the hemorrhage day because of a significant rise of plasma protein concentration. This may be important for the maintenance of blood volume after hemorrhage. Finally, fetal growth rate was determined by comparing fetal weight estimated in utero (from blood volume) with birth weight in 12 nonhemorrhaged control fetuses and in the 9 fetuses subject to 40-45% hemorrhage. The average rate of growth per day was 1.57 +/- 0.34% and -1.82 +/- 1.02%, respectively. The latter value is not significantly different from zero, suggesting that the acute blood loss impaired fetal growth.

Acute Disease↗
PubMed1995

Oxygen consumption, acid-base status, and behavior during and after acute, severe hemorrhage in fetal lambs.

The metabolic and behavioral effects of 40-45% hemorrhage (at approximately 1%/min) were studied in nine fetal lambs in utero (130-135 days of gestation) until 2 days posthemorrhage. Umbilical blood flow (Qum) fell from 192 +/- 14 to 100 +/- 9 ml.min-1.kg-1 at the end of blood loss, and on the day of hemorrhage it was linearly related to blood volume. However, on the posthemorrhage days, Qum was restored even though blood volume was still reduced. Fetal O2 delivery (DO2) fell with the decrease in Qum and later due to anemia (decrease in hematocrit from 33.4 +/- 1.2 to 23.6 +/- 1.2%), from 946 +/- 81 to 494 +/- 47 mumol.min-1.kg-1, but the decrease was lessened because of a rise in umbilical venous PO2 (31.7 +/- 2.6 to 45.9 +/- 2.8 mmHg). Fetal O2 consumption was reduced during and for 2 h after hemorrhage (262 +/- 17 to 190 +/- 16 mumol.min-1.kg-1), and this was associated with modest lactic acidemia (1.25 +/- 0.11 to 2.91 +/- 0.43 mM). There was also a temporary reduction in fetal breathing activity, low voltage electrocortical state, and rapid eye movements, but this was not associated with hypoxemia. It is concluded that reductions in fetal DO2 achieved via fetal blood loss are better tolerated than during hypoxemia and that the associated depression in fetal biophysical activities involves mechanisms other than systemic hypoxia.

Acid-Base Equilibrium↗
PubMed1995

Thoracoscopy versus thoracotomy: indications and advantages.

Although the diagnosis and treatment of intrathoracic diseases have been affected by the use of thoracoscopy, the indications and advantages of this procedure are poorly defined. To review the indications and results in a community practice, 52 consecutive cases of thoracoscopy were reviewed and the postoperative courses were compared to a control group of 43 simultaneous thoracotomies. Operative indications for thoracoscopy included investigation or treatment of a lung mass (n = 33), spontaneous pneumothorax (n = 10), mediastinal mass (n = 4), pleural effusion (n = 2), mesothelioma (n = 2), and a ruptured hemidiaphragm (n = 1). General endotracheal anesthesia was used in each case. Overall, thoracoscopy was successful in 40 cases (77%). Conversion to formal thoracotomy was required in 14 cases (27%) secondary to poor visualization or to aid in further dissection. Compared to thoracotomy, complication rates were less (7.6 vs 16.2%), hospital stay shorter (5.5 vs 8 days), ICU stay shorter (0 vs 2 days) and pleural drainage time less (2 vs 5 days) in the thoracoscopy group. In summary, 73% of the patients in this study who formerly would have undergone thoracotomy were successfully managed with thoracoscopy alone, with acceptable morbidity and mortality. These data define the indications, morbidity, and mortality of thoracoscopy and suggest that thoracoscopy may emerge as the procedure of choice in the diagnosis and management of many thoracic diseases.

Chest Tubes↗
PubMed1995

Efficacy of ceftriaxone versus cefazolin in the prophylactic management of extra-articular cortical violation of bone due to low-velocity gunshot wounds.

One hundred patients sustained gunshot wounds involving bone but not joint with a low-velocity bullet. Soft-tissue involvement was less than 1 cm at its greatest diameter. All patients were free from artery or nerve damage. No formal fixation of fracture was required. The results of the study suggest that patients need not be hospitalized longer than 2 days after an extra-articular, low-velocity gunshot wound that violates the cortex. In addition, through the use of long half-life antibiotics, such as ceftriaxone, the length of hospitalization may further be reduced to a day, while the potential for morbidity from infection is not increased.

Adult↗
PubMed1994

Effect of tissue inhibitor of the matrix metalloproteinases-2 expression on the growth and spontaneous metastasis of a human melanoma cell line.

In this study, we examined the effect of expression of tissue inhibitor of metalloproteinases-2 (TIMP-2) on the growth and dissemination of a highly metastatic human melanoma cell line (M24net). M24net melanoma cells express a number of matrix metalloproteinases (MMPs), including gelatinase A and B (MMP-2 and MMP-9) and interstitial collagenase (MMP-1) (A. M. P. Montgomery et al., Cancer Res., 53: 693-700, 1993). The activity of these proteases was effectively down-regulated by transfecting M24net cells with complementary DNA-encoding human TIMP-2. Overexpression of TIMP-2 markedly reduced melanoma growth in the skin of immunodeficient mice but did not prevent these highly malignant cells from spontaneously metastasizing to the lungs and lymph nodes of inoculated mice. We provide a mechanism to account for the growth inhibitory property of TIMP-2 based on its ability to regulate M24net cell growth in three-dimensional interstitial collagen. In the presence of this matrix, M24net cells assume a differentiated morphology and have a reduced growth rate. We present evidence that overexpression of TIMP-2 increases the susceptibility of M24net cells to growth inhibition and morphological differentiation by occluding interstitial collagen.

Animals↗
PubMed1994

Decapeptide agonists of human C5a: the relationship between conformation and spasmogenic and platelet aggregatory activities.

A series of decapeptide analogues corresponding to the C-terminal region of human C5a anaphylatoxin (C5a65-74) was synthesized with residue substitutions to restrict conformational flexibility in the C-terminus. These conformationally constrained peptides behaved as agonists of C5a in spasmogenic assays (smooth muscle contraction in human fetal artery, guinea pig ileum, and guinea pig lung parenchyma) as well as guinea pig platelet aggregation. There were significant correlations in the potencies of these peptides between the various assays. A structure-function analysis led to the identification of a preferred backbone conformation that correlated with the expression of these biological responses. These backbone structural motifs were consistent with a helix-like conformation for residues 65-69, an elongated structure for residues 70-71, and a beta-turn of either type II or type V for residues (71)72-74. The most potent of these agonists expressed almost 5% of the potency of natural C5a.

Amino Acid Sequence↗
PubMed1994

Pressor effect of ethanol in the isolated perfused human placental lobule.

Pharmacologically relevant concentrations of ethanol (0.01-0.3 g/%) were perfused via the fetal circulation in isolated human placental lobules. This resulted in a dose-related rise in fetal arterial pressure, which at 0.3 g/% ethanol, was 10.1 +/- 1.1 mmHg above the pre-drug baseline. The pressor responses to ethanol were (i) rapid in onset, reaching a stable plateau within 5-10 min following administration, (ii) readily reversible by perfusion with drug-free media, (iii) non-tachyphylactic and (iv) largely inhibited by the cyclo-oxygenase inhibitor, inhibitor, indomethacin (5 microM). This pressor action of ethanol in the fetal circulation may contribute to the pathogenesis of the fetal alcohol syndrome as well as represent an underlying mechanism of ethanol-induced hypertension.

Blood Pressure↗
PubMed1994

Anthelmintic suppression of Fasciola hepatica infections in sheep.

In an experiment to examine the use of anthelmintics to suppress the faecal egg output of Fasciola hepatica from sheep and reduce the prevalence of infection on a sheep farm with a history of chronic fasciolosis, triclabendazole was administered four times annually for three years. During the first year, treatments in April, June, August and October failed to reduce the prevalence. In the subsequent two years the first annual treatment was brought forward to January and February, and the prevalence was reduced by 74.6 and 69.7 per cent, respectively. The mean plasma gamma-glutamyl transpeptidase concentration of the flock was significantly reduced from 55.9 units/litre before the experiment to 40.9 and 38.3 units/litre. In the second and third years the packed cell volume increased from 0.29 litre/litre to 0.36 litre/litre and the percentage of infected Lymnaea truncatula decreased to zero.

Animals↗
PubMed1994

The juxtarenal abdominal aortic aneurysm. A more common problem than previously realized?

OBJECTIVE: To determine the incidence and treatment outcome of juxtarenal infrarenal aneurysmectomy in a vascular practice minimally biased by tertiary referral. DESIGN: A 5-year retrospective review of all aortic operations from our vascular registry was performed, and a case series of juxtarenal aneurysmectomies was analyzed. PATIENTS: Of 174 infrarenal aortic aneurysmectomies performed, 27 (15.5%) (95% confidence interval, 10.5% to 21.8%) involved the juxtarenal aorta. INTERVENTIONS: Juxtarenal involvement was unsuspected but found by aortography in 25 (93%) of 27 cases. Resection was performed transabdominally in 20 cases (74%) and retroperitoneally in seven cases (26%). MAIN OUTCOME MEASURES: Incidence, operative technique, morbidity, and mortality were analyzed and compared with those of historical controls. RESULTS: The incidence of juxtarenal aneurysmectomy was 15.5%. No operative deaths occurred, but there was a 19% incidence of surgical morbidity (including a 7% incidence of transient renal failure). The late survival rate was 89% (follow-up, 1 to 53 months; mean, 18 months). CONCLUSIONS: Juxtarenal aortic aneurysms are not uncommon. Successful management is possible, even outside the large referral center.

Aged↗
PubMed1994

Reversibility of tachyphylaxis to C5A in guinea pig tissues, perfused human placental lobule, and umbilical artery.

The spasmogenic effect of C5a is mediated by histamine and/or eicosanoids. Tachyphylaxis to this effect of C5a occurs rapidly, but the spasmogenic effects of C5a on a guinea pig lung parenchymal strips, field-stimulated ventricular papillary muscle, and human umbilical artery were completely restored by a 1-h period of drug-free rest, whereas that of guinea pig ileum was not. Perfusion of the isolated human placental lobule with C5a caused a transient pressor response that was largely abolished by indomethacin (5 microM), indicating mediation by cyclooxygenase metabolites. This pressor response to C5a was also completely restored following a 1-h rest period. The results show that tissue rest reverses tachyphylaxis to the spasmogenic effects of C5a in tissues where the response is mediated by cyclooxygenase metabolites. Where the response is mediated by histamine released by mast cells, restoration does not occur, presumably because of the catastrophic nature of mast cell degranulation. Histamine released in guinea pig papillary muscle by C5a may be from non-mast-cell sources.

Animals↗
PubMed1994

Does arterial inflow failure cause distal vein graft thrombosis? A prospective analysis of 450 infrainguinal vascular reconstructions.

Classically, inadequate arterial inflow, diseased runoff, and poor bypass conduit quality have all been cited as causes of infrainguinal vein graft failure. To examine the role of arterial inflow failure as a specific cause of vein graft thrombosis, we prospectively analyzed 450 consecutive infrainguinal vascular reconstructions by means of a strict duplex scan surveillance protocol at three teaching institutions from 1986 to 1993. Sixteen incidences of arterial inflow failure (11 occlusions and five high-grade stenoses) above previously placed infrainguinal vein grafts were identified in 14 patients and confirmed by arteriography. Despite these inflow failures, all 14 autogenous vein infrainguinal reconstructions remained patent on arteriography. These inflow failures were observed from 2 to 72 months (mean 16 months) after infrainguinal reconstruction. Immediate successful inflow repair was performed in 13 of the 16 failures. Conversely, among 450 grafts followed, 37 acute graft occlusions occurred-all with arteriographically or noninvasively documented normal inflow. Thus no graft in the series has yet failed as a result of inflow occlusion (mean follow-up 22 months; range 1 to 78 months). We thus conclude that properly constructed infrainguinal saphenous vein bypass grafts with an intact endothelium often remain patent through low-flow collateral vessels despite total arterial inflow occlusion. These data thus challenge the premise that arterial inflow disease is a major cause of infrainguinal vein bypass occlusion.

Adult↗
PubMed1994

Psychosocial effects of PCB contamination and remediation: the case of Smithville, Ontario.

A cross-sectional study design was used to investigate psychosocial effects in the population exposed to PCB contamination and remediation in Smithville, Ontario, Canada. Psychosocial effects were defined as the complex of distress, dysfunction and disability manifested in a wide range of psychological, social and behavioural outcomes as a consequence of actual or perceived contamination. This paper describes the results of logistic regression analyses conducted to investigate the determinants of psychosocial effects of exposure. The data come from an epidemiologic survey of a sample (N = 272) of Smithville households within 3 km of the site, and a sample from a matched comparison community (N = 263). Two types of outcome variables were used as indicators of psychosocial effects. Scores on the general measures of psychosocial health and well-being (the GHQ-20 and the somatic complaints checklist of the SCL-90) for the Smithville sample did not differ from those expected in a 'normal' population, nor did they differ from those in the comparison community. Scores on these outcomes were associated with plausibly linked independent variables, but were not associated with exposure to the PCB site. Results for site-specific outcome measures (concern and health concern) showed that moderate levels of concern reported by Smithville respondents were explained by concern about another local hazardous waste issue and could not be explained by PCB site exposure. We conclude from these results that local community context exerts an important influence on psychosocial effects of environmental contamination. Furthermore, the types of outcome measures employed and the timing of the research in the context of the site history were important factors in our ability to detect psychosocial effects of the PCB contamination and remediation in Smithville.

Adult↗