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Biomedical subjects

D Stewart

Publications and source records attributed to D Stewart.

At least 163 records · Page 9Linked to original sources
PubMed1997

Estimation of cardiac output by noninvasive echocardiographic techniques in the critically ill subject.

We evaluated the accuracy of cardiac output estimations by three transthoracic echocardiographic techniques in critically ill subjects. This study was a prospective comparison study carried out in a general intensive care unit of a teaching hospital. The subjects had a broad range of diagnoses including pulmonary embolus, cardiogenic shock, septic shock, Legionnaire's disease and perioperative myocardial infarction. All patients requiring pulmonary artery catheterization underwent echocardiographic cardiac assessment with comparison of findings to those obtained by thermodilution techniques. Nineteen studies on eighteen patients were performed, with cardiac output calculated by the two-chamber Simpson's, four-chamber Simpson's, and left ventricular outflow tract (LVOT) Doppler methods. Acceptable data was obtained in those patients without mitral regurgitation. There was good correlation between the thermodilution technique and Simpson's two-chamber method (r = 0.91), but less so with the Simpson's four-chamber method (r = 0.77). All studies were included in the LVOT Doppler method with a good correlation (r = 0.94). A plot of differences between methods using the Bland and Altman statistical method indicated that only the LVOT Doppler method demonstrated acceptable agreement with a mean of 0.2 litres/minute, standard deviation of 0.82 litres/minute and 95% limits of agreement of -1.5 to +1.9 litres/minute. We concluded that the LVOT Doppler method was the only one which demonstrated acceptable agreement between the thermodilution method and echocardiographic techniques in all critically ill patients studied.

Adolescent↗
PubMed1996

Review of larval and postlarval eye ultrastructure in the lamprey (Cyclostomata) with special emphasis on Geotria australis (Gray).

The literature dealing with the lateral eye in lampreys is briefly reviewed here. While there appears to be no longer much doubt that the short and long photoreceptor cells in the lamprey eye correspond to rods and cones, questions of dark/light adaptational changes, the nature of visual pigments, and the roles of retinal serotonin and melatonin need to be re-addressed. Eyes of the larval and postlarval ("macrophthalmia") stages of the lamprey Geotria australis were examined by electron microscopy and it was found that the larval retina is largely undifferentiated except for a small central zone surrounding the optic nerve head. The retina of the postlarval stage is fully differentiated and the photoreceptor outer segments undergo renewal, which appears to involve the retinal pigment epithelium (RPE). The distribution of larval RPE and choroidal pigments, postlarval ganglion cells, and the orientation of scleral collagen are unusual for vertebrates. No obvious positional or size differences of any retinal cell type were apparent between day- and night-fixed specimens.

Animals↗
PubMed1996

Diabetes mellitus, a predictor of morbidity and mortality in the Studies of Left Ventricular Dysfunction (SOLVD) Trials and Registry.

Diabetes is an independent predictor of morbidity and mortality in patients with symptomatic heart failure, patients with asymptomatic left ventricular dysfunction (defined as an ejection fraction of 35% or less), and in a broader registry population with less stringent entry criteria. Although the SOLVD Trials made a major clinical contribution by proving the value of enalapril, diabetes remains a significant predictor of outcome even after adjusting for treatment with enalapril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Vascular-derived myocardial contractile factor: positive myocardial inotropic substance released from medial layer of the canine aorta.

Interactions between the various cell types that make up the cardiovascular system are known to play an important role in maintaining homeostasis. One area about smooth muscle cells that has received little attention, despite the production of a wide variety of mediators by smooth muscle cells, is their effect on myocardial function. In this study, the myocardial contractile effects of four different types of dog aortic strips on rabbit papillary muscles were evaluated. Of these, medial vascular smooth muscle strips most consistently (65% of the time) produced a "vascular-derived contractile factor" (VDCF), which caused a 15% increase in isometric twitch tension and a 24% increase in isotonic twitch shortening with no change in twitch configuration. Endovascular strips with or without intact endothelium and complete aortic rings had less consistent effects. Vascular-derived contractile factor was stable after freezing at -80 degrees C, its activity was not modified by a broad spectrum peptidase, but it was heat-labile. The angiotensin II blocker, losartan, did not modify its effects. However, incubation with indomethacin did reduce, but did not eliminate, the contractile effects of vascular strips. The addition of alpha 1- and beta-blockers did not further modify the effects of VDCF. Endocardial endothelial removal increased the effects of VDCF. No correlation existed between endothelin levels and the contractile effects of vascular strips. It is concluded that VDCF is produced by the medial layer of large vessels but its exact cellular origin is uncertain. These findings expand the ever-increasing understanding of the inter-relationship between the structures that make up the cardiovascular system, and open the door to new studies evaluating the inter-relationship of vessels and myocardium.

Animals↗
PubMed1996

Phase II trial of docetaxel in patients with recurrent malignant glioma: a study of the National Cancer Institute of Canada Clinical Trials Group.

BACKGROUND: We conducted a phase II study to determine the response to, and toxicity of, docetaxel (Taxotere; Rhône Poulenc Rorer Pharmaceuticals, Inc) in patients with recurrent malignant glioma. PATIENTS AND METHODS: Eighteen patients with recurrent malignant glioma were treated with 100 mg/m2 (no prior chemotherapy) or 75 mg/m2 (prior adjuvant chemotherapy) of docetaxel intravenously over 1 hour, every 3 weeks. Premedication with dexamethasone, diphenhydramine and ranitidine or cimetidine was given to all patients. Five (28%) had gioblastoma multiforme (GBM) and the rest other malignant gliomas. Eleven (61%) had an ECOG performance status of 0 or 1, and 13 (72%) were on corticosteroids at the start of treatment. Rigorous response criteria were used. All were eligible and evaluable for response. RESULTS: No complete or partial responses were observed; the objective response rate was 0% (95% confidence interval: 0-15.3%). Patients received a median of 2 cycles (range, 1-6). Grade 3 or 4 neutropenia occurred in 17 (94%) patients and was associated with fever that required intravenous antibiotics in 4 (22%) patients. An additional patient received intravenous antibiotics for an infection not associated with neutropenia. Six (33%) patients had mild hypersensitivity reactions. Onychodystrophy, peripheral edema and peripheral neuropathy were uncommon and mild. CONCLUSIONS: Docetaxel has no significant activity in patients with recurrent malignant glioma.

Adult↗
PubMed1996

A comparison of hyperthermia cisplatin sensitization in human ovarian carcinoma and glioma cell lines sensitive and resistant to cisplatin treatment.

Two pairs of human tumor cell lines (glioma and ovarian carcinoma (OvCa) each having a parental cell line and cisplatin-resistant variant, were evaluated for (a) cisplatin response, (b) hyperthermia response, and (c) combined hyperthermia and cisplatin response. The two resistant lines had comparable resistant responses while for the parental lines, the OvCa was more sensitive than the glioma to cisplatin doses up to 14 microgram/ml. For the hyperthermia response, the OvCa parental line was more resistant than the variant line at low-temperature hyperthermia (41 degrees C or 42 degrees C) but became more sensitive at high temperature (45 degree C). For the glioma, the parental line was more sensitive to hyperthermia at all temperatures tested. Hyperthermia caused sensitization to cisplatin in all cell lines but was generally greater in the glioma cell lines. In the OvCa system, hyperthermia had a slightly greater sensitizing effect on the resistant cell lines, while in the glioma the opposite was true. The degree of sensitization increased with hyperthermia temperature. In summary, the results showed that there is no cross- resistance for hyperthermia and cisplatin, that the degree of thermal sensitization is not reduced in cisplatin- resistant cell lines, and that cisplatin thermal sensitization is cell-line and temperature dependent. Thus, hyperthermia can effectively improve tumor cell response to cisplatin and may be useful in overcoming resistance to cisplatin.

Carcinoma↗
PubMed1996

Tallimustine is inactive in patients with previously treated small cell lung cancer. A phase II trial of the National Cancer Institute of Canada Clinical Trials Group.

Tallimustine binds to the minor groove of DNA where it alkylates the N3 position of adenine and may interfere with gene transcription. We conducted a phase II trial of Tallimustine given at a dose of 750 micrograms/m2 intravenously every 4 weeks in patients with small cell lung cancer progressing or relapsing following cisplatin or carboplatin-based chemotherapy. We treated 14 eligible patients with a performance status 0, 1 or 2, bi-dimensionally measurable disease and adequate end-organ function. The main toxicity was neutropenia with a median granulocyte count of 0.1 x 10(9) per liter (range 0-3.9) and four patients (27%) developing febrile neutropenia. In addition, most patients (93%) experienced lethargy. No objective responses were seen. A mixed response was seen in one patient and three others had stable disease for a median of 3.7 months. We conclude that Tallimustine is an ineffective agent in previously treated small cell lung cancer.

Aged↗
PubMed1996

Myocardial infarction patients in the 1990s--their risk factors, stratification and survival in Canada: the Canadian Assessment of Myocardial Infarction (CAMI) Study.

OBJECTIVES: This study sought to evaluate the in-hospital and postdischarge mortality of patients with an acute myocardial infarction in the 1990s. BACKGROUND: The widespread implementation of therapeutic interventions that modify the natural history of coronary artery disease has led to changes in the profile and survival of patients with an acute myocardial infarction. Although data exist for selected subsets of patients with an acute myocardial infarction, at this time there is little recent prospective information on all patients presenting with an acute myocardial infarction, particularly for survival after hospital discharge. METHODS: All patients < or = 75 years old presenting with an acute myocardial infarction between July 1, 1990 and June 30, 1992 at nine Canadian hospitals were prospectively evaluated and followed up for 1 year. From November 1991, patients of all ages were included. In two centers, recruitment continued until December 31, 1992. A total of 3,178 patients were recruited. RESULTS: The in-hospital mortality rate of patients < or = 75 years old was 8.4%, and that at 1 year after hospital discharge was 5.3%. For patients of all ages recruited after November 1, 1991, the in-hospital mortality rate was 9.9% and 7.1% for 1 year after hospital discharge. For patients < or = 75 years old, age carried an independent in-hospital but no post discharge risk. Female patients had a twofold greater risk of dying in hospital. After hospital discharge, only 1.7% of patients < or = 75 years old and 1.9% of patients of all ages died of a presumed arrhythmic death. Premature ventricular contractions had no independent prognostic value. The relatively low in-hospital (5.3%) and postdischarge (6.1%) reinfarction rate may have contributed to improved survival. A greater reinfarction rate in patients >75 years old (17.4% vs. 9.6%, p < 0.001) may have contributed to their poorer outcome. CONCLUSIONS: One-year mortality after acute myocardial infarction continues to decrease, and changes in the prognostic value of traditional methods of risk stratification have occurred.

Age Factors↗
PubMed1996

The use of lithium in the treatment of aggressive behaviours with two brain-injured individuals in a state psychiatric hospital.

Brain-injured individuals often experience problems with aggression which can prevent full community reintegration. Two cases involving individuals (one 4 years, one 17 years post-injury) who had been placed in a state psychiatric hospital due to aggressive and/or self-injurious behaviours are discussed. Utilizing medication dosages and behavioural acuity indicators over a 2 year period, the authors demonstrate the efficacy of lithium carbonate in treating aggressive behaviours. Lithium, in concert with other medications, not only led to a decrease in the frequency of aggressive outbursts and in the need for restrictive and costly behaviour control techniques, but also allowed for a significant reduction in the use of neuroleptic medication in one case. The authors conclude that the use of lithium, within the context of an intensive, behavioural rehabilitation programme, may yield positive effects in the control of aggressive behaviour even in long-term post-injury cases.

Adult↗
PubMed1996

Concomitant low dose-rate irradiation and cisplatin treatment in ovarian carcinoma cell lines sensitive and resistant to cisplatin treatment.

Human ovarian carcinoma parental and cisplatin-resistant cells were evaluated for their radiation sensitivity to high and low dose-rate irradiation and for the effectiveness of cisplatin in radiosensitization. The cisplatin resistant variant A2780cp showed increased radiation resistance for both low dose-rate (LDRI) and high dose-rate irradiation. For cisplatin treatment for 1 h before and after HDRI there was radiosensitization in only the cisplatin-resistant variant. Concomitant cisplatin treatment during LDRI resulted in radiosensitization in both cell lines with dose-modifying factors ranging from 1.6 to 5.8. In this case greater radiosensitization was achieved in the parental cell line. In both cell lines the dose-modifying factors were larger when the cisplatin was refreshed every 6 h instead of 12 h during LDRI. These data show that cisplatin may be a very effective radiosensitizer when given during LDRI which is used in brachytherapy.

Antineoplastic Agents↗
PubMed1996

Phase II study of topotecan in patients with recurrent malignant glioma. National Clinical Institute of Canada Clinical Trials Group.

BACKGROUND: The NCIC Clinical Trial Group has an ongoing interest in assessing investigational agents in minimally pretreated patients with malignant glioma. Topotecan is one of the first topoisomerase I inhibitors to enter clinical trials and has shown early evidence of activity in several solid tumors. We have conducted a phase II trial of topotecan in patients with malignant glioma. METHODS: Adults with malignant glioma and recurrent contrast enhancing measurable disease (> or = 2 x 2 cm) were eligible. Topotecan 1.5 mg/m2 i.v. was given daily x five days every three weeks. Response and toxic effects were assessed at the end of each cycle. RESULTS: Thirty-one patients were entered onto the study: fifteen had glioblastoma, 16 anaplastic astrocytoma, all had prior radiation, 15 prior chemotherapy, and all were assessable for response and toxicity. Two patients (6%) responded: one had a complete radiographic response, but died with neutropenic sepsis, and the second had a prolonged partial response (> 97 weeks). Twenty-one patients (68%) had stable disease for five to 86 + weeks (median 19) and eight (26%) had progressive disease after one cycle. Toxicity was primarily hematologic; 18 (58%) had grade 4 neutropenia (< 0.5 x 10(9)/1), usually brief, and three (10%) grade 4 thrombocytopenia (< 25 x 10(9)/1). Twelve of 109 cycles (11%) were given at reduced dose. CONCLUSIONS: Topotecan in this dose and schedule has only modest activity in recurrent glioblastoma and anaplastic astrocytoma.

Adult↗
PubMed1996

Phase I study of paclitaxel (Taxol) and ifosfamide in previously untreated patients with advanced non-small-cell lung cancer. A study of the National Cancer Institute of Canada Clinical Trials Group.

BACKGROUND: Paclitaxel (Taxol) and ifosfamide are among the most active single agents for the treatment of non-small-cell lung cancer. We undertook this phase I dose escalation study to determine the maximum tolerated doses of these drugs which could be administered without growth factors to untreated patients with tumours of this type. PATIENTS AND METHODS: Forty patients with advanced non-small-cell lung cancer were treated with a 3-hour infusion of paclitaxel and a 1-hour infusion of ifosfamide every 3 weeks. Groups of 3 patients were entered at escalating dose levels in traditional phase I design. Starting doses were paclitaxel, 100 mg/m2, and ifosfamide 3 g/m2, and all patients received premedication with dexamethasone, diphenhydramine and a 5-HT3 blocker. Dose escalation occurred only after full toxicity assessment for 2 cycles for all patients in the dose level. RESULTS: Dose escalation of paclitaxel continued to 225 mg/m2 without dose-limiting toxicity, but further escalation was not attempted because of the known likelihood of neuro-toxicity above this level. Instead, ifosfamide was increased to 4 g/m2 for the final level. At these doses, dose-limiting myelosuppression was not seen, and there was only 1 episode of febrile neutropenia in 164 treatment cycles. Drug-related toxicities of ifosfamide included gross hematuria and confusion in 1 patient each, and paclitaxel-related symptoms included flu-like syndrome in most patients, mild to moderate arthralgia and/or myalgia in 8 and 25 patients, respectively, parasthesiae in 15 patients and mild to moderate hypersensitivity reactions in 15 patients each. Partial response was seen in 20.5% of patients (CI 9.3%-36.5%). SUMMARY: Out-patient paclitaxel given over 3 hours and single-dose ifosfamide over 1 hour may be combined safely without the need for hematopoietic growth factors for the treatment of patients with non-small-cell lung cancer. The recommended doses for phase II study are paclitaxel, 225 mg/m2 and ifosfamide, 4 g/m2 every 3 weeks.

Adult↗
PubMed1996

The gap between guidelines, practice, and knowledge in interpreting services for deaf students.

In this article, we examine the literature on educational interpreting for information related to optimal interpreting in school settings. this literature review is coupled with an examination of 15 guidelines for educational interpreters in school districts and programs for the deaf and hard of hearing across the United States. With this information, we then explore discrepancies between what guidelines recommend, what actually occurs in classrooms, and what research on the process of interpreting has found on the basis of three major areas of concern: the production of the message by the interpreter, the reception of the message by the student, and additional responsibilities required of interpreters working in school programs.

Journal Article↗