Search PubMed⌕ Search

Biomedical subjects

J R Stewart

Publications and source records attributed to J R Stewart.

At least 145 records · Page 8Linked to original sources
PubMed1984

Regional hyperthermia in the treatment of clinically advanced, deep seated malignancy: results of a pilot study employing an annular array applicator.

From October 1980 through December 1982, 46 patients were entered into a pilot study at the University of Utah Medical Center to assess the feasibility and safety of heating deep-seated, advanced, pelvic and abdominal malignancies with an annular array of electromagnetic wave (EMW) applicators. The patients, most of whom were heavily pretreated, were treated on a protocol in which most of the patients received combined hyperthermia and low dose X ray therapy. Discomforting local symptoms were the predominant treatment related acute side effects in 28 patients with pelvic disease, while systemic hyperthermia and associated symptoms were the predominant side effects in 18 patients with abdominal disease. Minor subacute toxicity was minimal and no serious treatment related, chronic toxicity was observed. The treatments of 22 patients with sufficiently detailed thermometry were analyzed at arbitrary index temperatures of 41 degrees C and 43 degrees C. Objective response rates in 22 evaluable patients were 67% and 9% for pelvic and abdominal sites respectively.

Abdominal Neoplasms↗
PubMed1984

Prevalence and significance of ventriculoatrial conduction.

Because retrograde atrioventricular conduction may predispose to pacemaker-induced tachycardia when DDD pacing is employed, we assessed ventriculo-atrial conduction in 117 patients undergoing electrophysiologic studies. Ventriculo-atrial conduction was present in 40% with a mean (+/- sem) conduction time of 205 +/- 12 ms. The maximum VA conduction time following minimum extrastimulus intervals averaged 258 +/- 14 ms. Antegrade AV nodal properties predicted VA conduction in only 67% by using stepwise discriminant analysis. Only the PR interval, AH interval, and AV nodal effective refractory periods were helpful in predicting ventriculo-atrial conduction. Although ventriculo-atrial conduction time increased on most antiarrhythmic drugs, it was infrequently eliminated.

Aged↗
PubMed1984

Past clinical studies and future directions.

The biological rationale for hyperthermia and radiation is strong, initial results in superficial tumor sites have established efficacy in human cancer, and deep tumor sites are beginning to yield to our efforts at deep regional heating. Major thrusts of new clinical research should go toward improved equipment and defining techniques with existing devices, which can lead us into definitive Phase III trials to assess the role of regional hyperthermia in primary multimodality management of cancer. Detailed thermometry is an absolute requirement for all future clinical studies. Invasive techniques to achieve deep hyperthermia are under investigation and may prove to be useful. Whole-body hyperthermia with radiation and/or chemotherapy has been less well studied in the laboratory than has local hyperthermia, and studies to show clinical efficacy in humans are lacking.

Clinical Trials as Topic↗
PubMed1984

Mediastinal tap as useful method for the early diagnosis of mediastinal infection.

The simple and quick technique of mediastinal aspiration (mediastinal tap) can facilitate the early diagnosis of mediastinitis in the postoperative cardiac surgical patient. This technique offers objective evidence of mediastinal infection before the development of wound drainage or sternal instability, or both.

Bacterial Infections↗
PubMed1983

Operative removal of misplaced Greenfield vena caval filters.

Operative retrieval has not been necessary in our experience, though interest has been expressed by other surgeons. Specifically, during removal the hooks of the filter may become attached to adjacent structures, making manipulation and eventual extraction difficult. Because the occasion for late removal of a misplaced filter may arise, we have developed this method using readily available materials. We anticipate that this technique will be most useful for removal of filters that have been in place for more than 7 days. A method to retrieve filters in place less than 1 week has already been reported [4]. We have found the technique quite satisfactory in experimental animals.

Filtration↗
PubMed1983

Change in the in vivo hyperthermic response resulting from the metabolic effects of temporary vascular occlusion.

Previous workers have reported that clamping of animal tumors in vivo enhanced the effect of hyperthermia; the enhancement has been attributed to pH and nutritional effects of vascular occlusion. It has not been clear, however, the degree to which improved heating patterns or effects on the tumor cells and vasculature from the clamping procedure itself might have contributed to the observed effect. In the experiments herein reported, care was taken to insure comparable heating of C3H mouse mammary tumors transplanted on the flank whether clamped or unclamped. Clamping for one hour with hyperthermia during the final 30 minutes caused a marked thermosensitization as measured by tumor control. The temperature at 30 minutes heating to control 50% of the tumors for 120 days (TCT 50-120) was reduced from 46.8 degrees C in controls to 43.5 degrees C in clamped tumors, a difference of 3.3 +/- 0.09 degrees C. No cytotoxicity from the clamping alone was evident by assessment of subsequent tumor growth and no lasting vascular effects could be detected by 133Xe washout and tumor growth. Since the techniques used produced essentially identical heating patterns, we conclude that the striking enhancement in hyperthermic response in clamped tumors can be attributed to the metabolic consequences of temporary vascular occlusion.

Animals↗
PubMed1983

Allergic contact dermatitis from an organic di-isocyanate.

Organic di-isocyanates are used widely in industry. The concomitant respiratory complications are well-known. Cutaneous problems precipitated by skin contact with these chemicals are less well recognised. Allergic contact dermatitis caused by exposure to di-cyclohexylmethane 4,4'-di-isocyanate has been demonstrated in a factory where it was used to form a surface-coating polyurethane. Attention to hygiene methods may have reduced the incidence of cases.

Adolescent↗
PubMed1983

Ruptured lumbar artery pseudoaneurysm: an unusual cause of retroperitoneal hemorrhage.

A patient with a functioning renal transplant presented for treatment 8 years after operation with acute retroperitoneal hemorrhage ipsilateral to the allograft. A ruptured false aneurysm of the lumbar artery was identified and was treated initially with balloon catheter occlusion, then operative ligation, with satisfactory result.

Abdominal Muscles↗
PubMed1983

Reduction of myocardial ischemic injury with oxygen-derived free radical scavengers.

Experimental data suggesting that oxygen-derived free radicals may play a role in the myocardial injury associated with ischemia and reperfusion are presented. In several studies of prolonged global myocardial ischemia, the administration of free radical scavenging agents, such as superoxide dismutase, catalase, and mannitol, resulted in significantly better recovery of left ventricular function following reperfusion. In a region-at-risk model of localized myocardial ischemia, both superoxide dismutase and allopurinol significantly reduced the extent of myocardial necrosis that developed following reversible coronary arterial branch occlusion. The manner in which oxygen-derived free radicals may be harmful is examined. In particular, the possibility that these toxic species are involved in the exacerbation of the ischemic injury that develops upon reflow and reoxygenation is examined.

Animals↗
PubMed1983

In vivo cytotoxicity of misonidazole and hyperthermia in a transplanted mouse mammary tumor.

The cytotoxicity of misonidazole (miso) in vivo in unclamped tumors at hyperthermic temperatures, and in clamped tumors at hypothermic, euthermic, and hyperthermic temperatures has been examined. No cytotoxicity, measured as increased tumor control, was observed in unclamped tumors heated 30 min after systemic miso administration. This may reflect the short serum half-time of miso in the mouse and a small hypoxic fraction in this tumor system. There was, however, significant miso cytotoxicity in clamped tumors at euthermic and hyperthermic temperatures when the clamp was applied 30 min after systemic miso. The degree of cytotoxicity observed was dependent upon the temperature of incubation, the length of clamping, and the dose of miso.

Animals↗
PubMed1983

Inhibition of surgically induced ischemia/reperfusion injury by oxygen free radical scavengers.

Recent experimental work implicates oxygen free radicals as mediators of ischemia/reperfusion injury. A simple cardioplegic solution was designed to scavenge superoxide anion and hydroxyl free radical with superoxide dismutase (10 micrograms/ml), mannitol (325 mOsm/L), and KCl 25 mEq/L (FRS). Hemodynamic and subcellular functions were studied in seven in situ canine models of hypothermic global ischemia receiving FRS, compared to a group (n = 7) receiving hyperosmolar, hyperkalemic saline (HSK) and to a standard model of topical hypothermia (TH, n = 5). Following 60 minutes of ischemia (10 degrees to 15 degrees C), hearts were reperfused and rewarmed. After 45 minutes of reperfusion, left ventricular peak systolic pressure (LVPSP), developed pressure (LVDP), dP/dt max, -dP/dt max, compliance, and elastic stiffness constant (K) were improved in the FRS group and not significantly different from control. Sarcoplasmic reticulum (SR) calcium transport in the FRS group was significantly improved (control = 1.077 +/- 0.022, TH = 0.754 +/- 0.018, HSK = 0.725 +/- 0.05, and FRS = 0.966 +/- 0.05 mumol/mg-min). Calcium adenosine triphosphatase (ATPase) activity did not differ significantly from control at pH 7.0. In this model of hypothermic global ischemia and reperfusion, free radical scavengers provide significant protection of mechanical and subcellular function. These findings support the hypothesis that oxygen free radicals are important mediators of myocardial ischemia and reperfusion injury.

Animals↗
PubMed1982

Transvenous vena caval filtration and pulmonary embolectomy.

The diagnosis of deep vein thrombosis or pulmonary embolism can be made accurately using angiographic and radioisotopic techniques. Utilizing hemodynamic data, it is possible to classify patients with pulmonary embolism into five groups, which is helpful for planning therapy and assessing prognosis. Surgery for pulmonary embolism has evolved to include intraluminal methods of vena caval filtration for prevention of recurrent pulmonary embolism and transvenous extraction of pulmonary emboli. Though the majority of patients surviving pulmonary embolism can be managed medically with anticoagulation, a significant number will require surgical intervention. The development of transvenous methods allows effective emergency management of major pulmonary embolism, even in hospitals that do not have the capability for cardiopulmonary bypass.

Blood↗