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Biomedical subjects

M Shea

Publications and source records attributed to M Shea.

At least 55 records · Page 3Linked to original sources
PubMed1990

Diagnosis and control of neonatal losses in sheep.

Perinatal mortality is affected by a variety of management factors and disease processes that create significant losses for the sheep industry. Annual production losses prior to weaning include roughly 15% to 20% of the lamb crop. The majority of these perinatal losses occur during the prenatal, natal, and early postnatal periods, with the predominant wave of mortality occurring during the first several days following birth. Causes of perinatal mortality may vary between flocks and between geographic areas; however, four dominant categories of lamb loss consistently surface: (1) abortions; (2) hypothermia, starvation, and exposure; (3) pneumonia; and (4) stillbirth and dystocia. They account for roughly 50% to 75% of all documented perinatal losses. Veterinarians and producers need to work together to document the type of losses that occur in a given flock and then design economic prevention programs that address these problems. In most cases, traditional prevention programs will need to be replaced by a comprehensive management scheme addressing nutrition, genetics, housing, marketing, lambing husbandry, and labor.

Abortion, Veterinary↗
PubMed1990

Compressive strength of autologous and allogenous bone grafts for thoracolumbar and cervical spine fusion.

The selection of the bone graft type for stabilization of spinal fusion depends on availability, the clinical situation, and the desired mechanical stability. The authors determined the potential immediate postoperative compressive strength of various types of bone grafts under axial compression on a material testing machine. The fibular strut graft (5,070 +/- 3,250 N, mean +/- standard deviation [SD]) was significantly stronger (P less than 0.05) than the anterior (1,150 +/- 487 N) and posterior (667 +/- 311 N) iliac crest grafts, and the rib grafts (452 +/- 192 N). Hydroxyapatite grafts with a pore size of 200 mu were significantly stronger (P less than 0.05) than those with a pore size of 500 mu (1,420 +/- 480 N versus 338 +/- 78 N). Ethylenoxide sterilization had no significant effect on the immediate compressive strength. Bicortical and tricortical Bailey-Badgley and Cloward bone grafts also were compared. Results showed that all cervical graft types may be sufficiently strong to support sizable loads.

Aged↗
PubMed1989

Nanophthalmos in sisters, one with exfoliation syndrome.

In a consanguineous family of two siblings, both with nanophthalmos, one was found to also have bilateral exfoliation syndrome. This combination of conditions has not, to our knowledge, previously been reported and has not had any apparent negative consequences. Her sister has manifested typical complications of nanophthalmos, including angle-closure glaucoma initially and, eventually, severe uveal effusion after cataract surgery.

Aged↗
PubMed1988

The role of echocardiography and CT in the diagnosis of cardiac tumors.

A young male who presented with atypical chest pain was found to have a primary cardiac tumor. Chest X-ray, electrocardiogram, and echocardiographic findings can be nonspecific. Differential diagnosis and the role of different diagnostic modalities including echocardiogram, computerized tomography and magnetic resonance imaging are discussed.

Adult↗
PubMed1987

Sequential infusional 5-fluorouracil followed by concomitant radiation for tumors of the esophagus and gastroesophageal junction.

Thirteen patients with esophageal or gastroesophageal tumors with regional disease only were treated with sequential combined therapy. Weeks 1 to 6 continuous (24 hours) infusion 5-fluorouracil (5-FU) 300 mg/m2/d; weeks 6 to 10 or 12 infusional 5-FU administered concomitantly with radiation to the primary tumor site using standard fractionation with a cumulative median dose of 5000 rad; range 4400 to 6900 rad. Surgery was performed in five patients. All patients were evaluable for assessing response to the initial 5-FU infusion and 11/13 patients demonstrated tumor regression. Of 12 evaluable patients subsequently receiving combined infusional 5-FU and concomitant radiation, all 12 achieved complete clinical (10) or pathologic (two) tumor regression. Two of five patients having surgical resection had no pathologic evidence of tumor. All patients had relief of dysphagia within 1 week of initiating chemotherapy. Acute complications of therapy included stomatitis (two patients); hand-foot syndrome (two patients), and subclavian vein thrombosis (two patients). Stricture requiring periodic dilation occurred in three patients, and one patient developed a tracheoesophageal fistula at 36 months. Local control was maintained in 12/13 evaluable patients. Four of 13 patients were alive and without disease at 12 to 46 months. Nine patients died of distant metastases at 6 to 40 months. Median survival for the whole group was 16 months. Ten of the 13 patients (77%) survived for more than 1 year and 3/13 (22%) survived more than 3 years. This pilot study demonstrates the activity of 5-FU administered on an infusion schedule in both squamous and adenocarcinoma of the esophagus and the capacity to deliver infusional 5-FU throughout standard fractionation radiation. The local control and survival data may provide a basis for expanded Phase II trials, and a comparative trial against surgery alone might also be justified.

Aged↗
PubMed1986

Character of transient ischemia in angina pectoris.

There is growing interest in the possible therapeutic and prognostic significance of silent myocardial ischemia in coronary artery disease (CAD) and its detection by ambulatory electrocardiographic (ECG) monitoring. In 100 apparently healthy normal subjects (20 with angiographically normal coronary arteries), Holter monitoring revealed significant ST-segment depression in only 2 (both over 40 years, one with positive treadmill test, the other with risk factor for CAD). No significant ECG changes were found in those with normal coronary vessels. In 30 patients with documented CAD, significant ST-segment depression during 1,934 episodes over 446 days of monitoring over 18 months was found. Only 24% of the episodes were associated with angina. Asymptomatic and symptomatic episodes were associated with comparable changes in perfusion detected by positron emission tomography. Heart rate increases greater than 10 beats/min preceding the onset of the ST-segment changes occurred in only 23% of the episodes. There was considerable variability in the ST-segment changes in the same patient monitored serially over long periods of time. The data indicate that it is extremely uncommon for patients without CAD to exhibit silent myocardial ischemia, whereas patients with stable angina exhibit frequent, variable and often asymptomatic ECG evidence of myocardial ischemia rarely triggered by increases in heart rate. These findings are likely to be of therapeutic and prognostic significance.

Adult↗
PubMed1984

Transient ST-segment depression as a marker of myocardial ischemia during daily life.

Patients with angina and coronary artery disease (CAD) have many episodes of transient ST-segment depression during ordinary daily life, and these are often asymptomatic. To investigate this signal as a marker of myocardial ischemia, 30 patients with chronic stable angina and CAD underwent positron tomography, recording the regional myocardial uptake of rubidium-82, pain and ST-segment changes before, during and after 59 technically satisfactory exercise tests, 35 cold pressor tests and 22 episodes of unprovoked ST depression. Exercise resulted in 53 episodes of ST depression with angina and in 5 episodes without pain. After cold pressor tests, there were 3 episodes of ST depression and pain and 12 of painless ST depression. Only 9 episodes of unprovoked ST depression were accompanied by pain. Tomography showed independent evidence of ischemia in 63 (97%) of the total 65 episodes of ST depression with angina and in all 30 episodes of painless ST depression. In each patient perfusion defects occurred in the same myocardial segment during painful and painless ST depression and responses were significantly different from those in 16 normal subjects studied in the same way. These findings support the use of transient ST depression in continuous monitoring to assess the activity of CAD, but only in patients with typical angina pectoris, ST depression during exercise and proved CAD. They strengthen the evidence derived from ambulatory monitoring for a wider picture of the disease than is generally appreciated, with more frequent episodes of silent myocardial ischemia than of angina pectoris.

Adult↗
PubMed1984

Silent myocardial ischaemia due to mental stress.

Patients with angina and coronary disease have many episodes of symptomless transient myocardial ischaemia, most of which cannot be explained by physical exertion. 16 patients with typical stable angina pectoris were examined to test the hypothesis that these episodes can be triggered off by ordinary daily events, such as changes in mental activity. Regional myocardial perfusion and ischaemia were assessed by measurement of the uptake of rubidium-82 with positron tomography after mental arithmetic and physical exercise. With mental arithmetic, 12 (75%) patients had abnormalities of regional perfusion, accompanied in only 6 by ST-segment depression and in 4 of these 6 by angina, leaving 6 patients with perfusion abnormalities but neither pain nor electrocardiographic changes. After exercise, all the patients showed abnormal regional myocardial perfusion in the segments that became ischaemic with mental arithmetic. This was accompanied by ST depression in all and angina in 15. The association between mental activity and myocardial ischaemia may operate frequently during everyday life and may explain many of the transient and symptomless electrocardiographic changes in patients with coronary disease.

Activities of Daily Living↗
PubMed1984

High-performance liquid chromatographic measurement of exogenous thiosulfate in urine and plasma.

A simple technique using reverse-phase ion-pair liquid chromatography for measurement of exogenous thiosulfate is described. Accurate measurement of thiosulfate in plasma and urine was permitted by precolumn derivatization with monobromobimane, a substance that readily yields fluorescent compounds upon reaction with a variety of biologically important nucleophiles including glutathione, cysteine, and sulfite. Using an injection volume of 50 microliters, as little as 0.16 nmol of thiosulfate was reliably measured. The interassay precision of the method was reflected by a coefficient of variation of 7.7% while the coefficient of variation for interassay analysis was 2.6%. Recovery of thiosulfate from plasma was 96.9 +/- 3.2% and greater than 98% from urine. The simplicity, sensitivity, and precision of the method make it ideal for the study of thiosulfate and other important nucleophiles in body fluids.

Chromatography, High Pressure Liquid↗
PubMed1984

Kinetics of sodium thiosulfate, a cisplatin neutralizer.

Sodium thiosulfate kinetics were studied in eight subjects, six of whom were given the drug as a cisplatin neutralizer. Thiosulfate at a dose of 12 gm/m2 was injected by continuous intravenous infusion over 6 hr. Under these conditions, steady-state plasma concentrations were not achieved and apparent volume of distribution could not be calculated. The drug was eliminated from plasma by first-order kinetics, and the data best fit a one-compartment kinetic model with a t1/2 (mean +/- SD) of 80 +/- 38 min. Total body thiosulfate clearance was 190 +/- 76 ml/min/m2 and renal clearance was 50 +/- 11 ml/min/m2. The plasma elimination t1/2 and renal thiosulfate clearance correlated poorly with clearance of endogenous creatinine. Only 28.5% +/- 9.4% of the thiosulfate was recovered unchanged in the urine. Urinary excretion was rapid, with approximately 95% of recoverable drug eliminated within 4 hr after termination of the infusion. No toxic effects of thiosulfate were observed. These data provide the basis for the rational development of dose schedules when sodium thiosulfate is used as a cisplatin neutralizer.

Adult↗
PubMed1984

Different mechanisms for the relief of angina after coronary bypass surgery. Physiological versus anatomical assessment.

To determine the physiological effect of coronary artery bypass surgery and the mechanisms for pain relief, 15 patients with exertional angina were studied before and after operation. Before the operation conventional tests included exercise tests (all positive) and coronary angiography (all patients had greater than or equal to 70% stenosis of major vessels). In addition, ambulatory electrocardiographic monitoring during 48 hours detected 92 episodes (greater than or equal to 1 mm) of ST depression. Regional myocardial perfusion was assessed with positron tomography using rubidium-82 (t1/2 78 s) and this showed reversible inhomogeneity with absolute regional reduction of cation uptake after exercise in all 15 patients. After coronary surgery 10 of the 15 patients had (a) no angina, (b) patent grafts (three or more), (c) no evidence of ischaemia during ambulatory monitoring out of hospital, and (d) homogeneous perfusion with reversal of the disturbances in regional myocardial perfusion after exercise. After operation one of the 15 patients had no angina and showed silent infarction in the segment that was previously ischaemic but supplied by a patent graft. All but one of the remaining patients had no angina, patent grafts, but disturbances of regional myocardial perfusion with silent ischaemia on exercise. Two of these patients continued to have asymptomatic and ischaemic episodes of ST depression during ambulatory monitoring out of hospital. This physiological study of regional myocardial perfusion in patients in hospital and in those with ischaemia out of hospital showed that three different mechanisms may account for the relief of pain--improved perfusion, infarction, and silent ischaemia. Silent ischaemia in particular raises puzzling pathophysiological and therapeutic questions that may affect prognosis and the interpretation of clinical trials.

Adult↗
PubMed1983

Early vitrectomy in proliferative diabetic retinopathy.

Pars plana vitrectomy was carried out in 140 patients with useful to excellent visual acuity associated with elevated proliferative diabetic retinopathy. A substantial reduction in the incidence of traction retinal detachment occurred and a significant improvement in visual prognosis was achieved.

Diabetic Retinopathy↗