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Biomedical subjects

S M Davis

Publications and source records attributed to S M Davis.

At least 19 recordsLinked to original sources

Streptokinase in acute stroke: effect on reperfusion and recanalization. Australian Streptokinase Trial Study Group.

The Australian Streptokinase Trial was a randomized, double-blind, placebo-controlled trial, in which streptokinase (SK, 1.5 million IU I.V.) was given within 4 hours of stroke onset. In a subset of 37 patients, 99mTc-labeled D,L-hexamethylpropylene amine oxime single-photon emission computed tomography (SPECT) and/or transcranial Doppler (TCD) studies were performed before and after therapy to test the hypothesis that SK may improve the hemodynamic measures of reperfusion/recanalization rates (TCD parameter) within 24 hours. Eighteen patients received SK and 19 placebo. Baseline characteristics were similar in both groups, and there were no differences in clinical outcomes assessed at 3 months after stroke. Although there was no increase in the group mean perfusion defect or volume on SPECT after thrombolytic therapy, a larger number of patients demonstrating the combined end point of reperfusion or recanalization was seen in the SK group (13/14, 93%) than in the placebo group (7/14, 50%; p = 0.01). Although SK given within 4 hours of acute ischemic stroke appears to improve arterial patency/tissue reperfusion, this effect is neither early nor extensive enough to influence overall clinical outcome.

Acute Disease

Adaptation of the Dartmouth COOP Charts for use among American Indian people with diabetes.

OBJECTIVE: To adapt the Dartmouth COOP Charts for use among American Indians with diabetes and to evaluate the operating characteristics of the adapted charts because measures of health status have not been evaluated for use among American Indians with diabetes. RESEARCH DESIGN AND METHODS: American Indian adults participated in focus group conferences to adapt and review the Dartmouth COOP Charts for use in American Indian communities. American Indian participants with diabetes were interviewed and administered the adapted charts. The operating characteristics of the charts were evaluated by measuring internal and external consistency, reliability, and acceptability. RESULTS: Some of the wording and pictures were considered to be offensive and culturally inappropriate in American Indian communities. The adapted charts showed internal consistency in a comparison of interchart variables. CONCLUSIONS: The adapted Dartmouth COOP Charts are more culturally acceptable than the original charts and appear to measure constructs adequately.

Adolescent

Risk factors for stroke due to cerebral infarction in young adults.

BACKGROUND AND PURPOSE: Stroke in the young is particularly tragic because of the potential for a lifetime of disablement. More than 10% of patients with stroke due to cerebral infarction are aged 55 years or younger. While a number of studies have addressed the issue of stroke mechanism in the young, quantitation of risk factors has rarely been undertaken. Given the importance of risk factor assessment in primary prevention, we aimed to assess this using case-control methodology in a hospital-based series and community-based control subjects. METHODS: A total of 201 consecutive patients with first-onset stroke due to cerebral infarction aged 15 to 55 years (mean, 45.5 years) were accrued from four teaching hospitals during 1985 to 1992 and compared with their age- and sex-matched neighborhood controls. Information concerning potential risk factor exposure status was collected by structured questionnaire at interview. Stroke risks were estimated by calculating the odds ratios with multivariate logistic regression. RESULTS: Significantly increased risk of stroke was found among those with diabetes (odds ratio, 11.6 [95% confidence intervals, 1.2 to 115.2]), hypertension (6.8 [3.3 to 13.9]), heart disease (2.7 [1.1 to 6.4]), current cigarette smoking (2.5 [1.3, 5.0]), and long-term heavy alcohol consumption (> or = 60 g/d) (15.3 [1.0 to 232.0]). However, heavy alcohol ingestion (> or = 60 g) within 24 hours preceding stroke onset was not a risk factor (0.9 [0.3 to 3.4]). CONCLUSIONS: Diabetes, hypertension, heart disease, current smoking, and long-term heavy alcohol consumption are major risk factors for stroke in young adults. Given that the majority of these factors are either correctable or modifiable, prevention strategies may have the potential to reduce the impact of stroke in this age group.

Adolescent

Suspected lamotrigine-induced toxic epidermal necrolysis.

OBJECTIVE: To describe a patient who developed toxic epidermal necrolysis (TEN) possibly secondary to lamotrigine use. CASE SUMMARY: A 74-year-old white man with a history of probable complex partial seizures was admitted to the neurology service for a prolonged postictal state. His antiepileptic regimen was changed while he was in the hospital to include lamotrigine. After 19 days of hospitalization and 14 days of lamotrigine therapy, the patient became febrile. The next day he developed a rash which progressed within 4 days to TEN, diagnosed by skin biopsy. All suspected drugs were discontinued, including lamotrigine. The patient was treated with hydrotherapy in the burn unit. His symptoms improved and he was discharged from the hospital 26 days after the rash developed. DISCUSSION: During lamotrigine's premarketing clinical trials, the manufacturer reported several cases of Stevens-Johnson syndrome and TEN. There are several published case reports of lamotrigine-induced severe skin reactions. All of these reports included patients being treated with both valproic acid and lamotrigine. Our patient was exposed to phenytoin, carbamazepine, clindamycin, and lamotrigine, but not valproic acid. The patient reported prior use of phenytoin with no skin rash. Carbamazepine was the antiepileptic drug the patient was maintained on prior to his hospital admission, and the symptoms of TEN resolved while he was still receiving carbamazepine. The patient received only two doses of clindamycin, which makes this agent an unlikely cause of TEN. CONCLUSIONS: Because of the temporal relationship of the onset of the patient's rash and several drugs that are known to cause severe rashes, it is not certain which drug was the definite culprit. However, based on the evidence from the literature, lamotrigine appears to be the causative agent.

Aged

Lung volume reduction surgery at a community hospital: program development and outcomes.

STUDY OBJECTIVES: Description of the development and results of a program in lung volume reduction surgery (LVRS) at a community hospital. DESIGN: Prospective data collection. SETTING: A 320-bed community hospital. PATIENTS: Fifty-five patients consecutively discharged from the hospital following LVRS. The mean preoperative FEV1 averaged 28% (+/-8%) of predicted values, while the preoperative PaCO2 averaged 49 mm Hg (+/-11.5 mm Hg). Forty-eight patients completed a preoperative conditioning regimen and underwent the procedure on an elective basis. Seven patients underwent the procedure during a hospital admission for a COPD exacerbation. Eight patients required mechanical ventilation preoperatively, including three who had required long-term mechanical ventilatory support. RESULTS: Three patients (5%) died in the hospital following surgery. One patient developed chronic ventilator dependence. All three of the patients who required long-term mechanical ventilation preoperatively were weaned from the ventilator and returned home. Follow-up pulmonary function testing is available for 42 patients 3 months after surgery, and for 20 patients 6 months after the operation. At 3 months, the mean FEV1 improved 0.19 L (p=0.0002), the mean improvement for FVC was 0.37 L (p=0.0001), and the mean drop in residual volume was 0.97 L (p=0.0001). Similar changes are seen at 6 months. Highly significant improvements were also seen in quality of life measurements and exercise performance. The benefits of surgical treatment of emphysema seemed similar in both elective and urgent groups. CONCLUSIONS: LVRS can be done safely and effectively at a community hospital, with significant improvement in pulmonary function and quality of life.

Adult

Risks of infection or reactivation of tuberculosis associated with chronic corticosteroid therapy.

Although corticosteroids are known to be immunosuppressive, there have been no studies to show that use of corticosteroids increases the risk of developing new tuberculosis or reactivating old tuberculosis. In fact, corticosteroids are recommended for the treatment of several forms of tuberculosis, such as pleural tuberculosis, genitourinary tuberculosis, and tuberculous meningitis. Clinicians should still be alert for tuberculosis appearing in immunocompromised patients as a disseminated infection or for tuberculosis that is atypical in appearance.

Adrenal Cortex Hormones

Volumetric analysis of cerebral hypoperfusion on SPECT: validation and reliability.

UNLABELLED: A method of volumetric analysis of hypoperfusion on 99mTc-labeled hexamethylpropylene amine oxime SPECT has been developed. This analysis integrates both the size and severity of perfusion reduction, yielding an equivalent volume of cortical tissue having zero blood flow, or the effective hypoperfusion volume. This study aimed to validate the methodology in vitro using the Hoffman brain phantom and two different camera systems, to examine the relationship between spatial resolution and accuracy of volume measurement and to assess the interobserver variability in SPECT studies of stroke patients. METHODS: Simulated cortical lesions of three different sizes were sequentially incorporated into the Hoffman brain phantom and imaged using both single- and triple-head camera systems. For each system and for each lesion size, successive acquisitions were performed using three progressively larger radii of camera rotation. The hypoperfusion volume for each study was measured three times by a blinded observer, and the percentage difference from the true lesion volume was then calculated. SPECT studies of 32 stroke patients were independently analyzed by two blinded observers. RESULTS: At the smallest radii of rotation, mean (s.d.) percentage difference between observed and true volumes was 0.90% (4.80%) for the triple-head and 4.50% (11.58%) for the single-head system. The degree of overestimation was similar for both systems. Percentage overestimation was strongly associated with radius of rotation (B = 0.71 +/- 0.32, p = 0.04 for the triple-head system; B = 1.26 +/- 0.55, p = 0.03 for the single-head system) but not with lesion size. The mean difference between hypoperfusion volumes of stroke patients obtained by two observers was 0.045 (3.240) cm3, which was not significant. CONCLUSION: This study has shown that this technique of volumetric analysis of regional hypoperfusion on SPECT is both highly accurate and reproducible between two different camera systems. The degree of overestimation chiefly relates to diminishing spatial resolution. Despite some element of subjectivity, the interobserver variability is negligible.

Animals

Food preferences, practices, and cancer-related food and nutrition knowledge of southwestern American Indian youth.

BACKGROUND: Pathways to Health is a cancer prevention and health promotion curriculum for fifth- and seventh-grade Navajo and Pueblo students living in New Mexico. METHODS: A diet and nutrition questionnaire was administered to 1007 fifth- and seventh-grade students before beginning the Pathways to Health intervention. Sections of the questionnaire included listing favorite foods, frequency of intake of selected foods (e.g., "How often do you eat vegetables?"), targeted food practices (e.g., "When you eat chicken, do you eat the skin?"), and applied dietary fat and fiber knowledge questions. Descriptive analyses were generated by grade, gender, and tribe. RESULTS: Students' favorite foods were pizza, hamburgers, and tacos. Only 35.7% of students reported consuming the U.S. Dietary Guidelines recommendation of two or more daily servings of fruit, with only 19.3% reporting more than once-a-day intake of vegetables. The mean score (percent correct responses) to questions identifying common food sources of dietary fat and fiber, and other cancer-related nutrition knowledge questions, was 45.2% and 57.9% for fifth- and seventh-grade students, respectively. CONCLUSIONS: These and related data support the need for nutrition education interventions in this population that target essential cancer prevention skills and motivational information required to make positive dietary choices.

Adolescent

Four Corners Research Consortium for Native Americans and cancer research.

Cancer morbidity and mortality in Native Americans in the Southwestern four-corners region of the United States (Arizona, Colorado, New Mexico, and Utah) is of critical concern to public health workers, health care providers, cancer researchers, and Native American communities of the region. As a follow-up to the national conference in Seattle, Washington, representatives from the Arizona, Colorado, New Mexico, and Utah Cancer Centers, the AMC Cancer Research Center, and the Indian Health Service participated in a regional conference on September 26, 1995. The primary reason for the "Four Corners Consortium" meeting was to assess cancer research activities in each state and to determine how Native American cancer research could be organized in the four-state region. One interest of the group was to determine strategies to explore why some cancers are more or less prevalent among Southwest Native American populations and to evaluate how the group might jointly establish research that would address the cancer needs of Southwestern tribes.

Arizona

Streptokinase for acute ischemic stroke with relationship to time of administration: Australian Streptokinase (ASK) Trial Study Group.

OBJECTIVES: To determine whether the administration of 1.5 million units of streptokinase intravenously within 4 hours of the onset of acute ischemic stroke would reduce morbidity and mortality at 3 months and whether outcomes may be better for those receiving therapy within 3 hours of stroke onset compared with those receiving it after 3 hours. DESIGN: Randomized, double-blind, placebo-controlled trial with 3-month follow-up. PARTICIPANTS: A total of 340 patients, aged 18 to 85 years, with moderate to severe strokes were randomized from 40 centers throughout Australia from June 1992 to November 1994. INTERVENTION: Administration of 1.5 million units of streptokinase or placebo intravenously in 100 mL of normal saline over 1 hour. MAIN OUTCOME MEASURE: Combined death and disability score (Barthel index <60) 3 months after the stroke. RESULTS: Using an intention-to-treat analysis with a combined death and disability score at 3 months after stroke as the primary end point, we found a nonsignificant overall trend toward unfavorable outcomes for streptokinase vs placebo (relative risk [RR] of unfavorable outcome, 1.08; 95% confidence interval [CI], 0.74-1.58) and an excess of hematomas (13.2%[12.6% symptomatic] in the treated group, 3% [2.4% symptomatic] for placebo [P<.01]). However, poor outcomes were confined to patients receiving therapy more than 3 hours after stroke onset (RR of unfavorable outcome, 1.22; 95% CI, 0.80-1.86). In contrast, among the 70 patients who were entered into the trial within 3 hours of stroke onset, there was a trend toward improved outcomes for those who received streptokinase (RR of unfavorable outcome, 0.66; 95% CI, 0.28-1.58), and this outcome pattern was significantly better than for those receiving therapy after 3 hours (P=.04). Streptokinase administration resulted in excess deaths in the group treated after 3 hours (RR, 1.98; 95% CI, 1.18-3.35), but not among those treated within 3 hours (RR, 1.11; 95% CI, 0.38-3.21). CONCLUSION: The administration of streptokinase within 4 hours of acute ischemic stroke increased morbidity and mortality at 3 months. While treatment within 3 hours of stroke was safer and associated with significantly better outcomes than later treatment, it showed no significant benefit over placebo. The timing of thrombolytic therapy for acute stroke is critical.

Acute Disease

Streptokinase increases luxury perfusion after stroke.

BACKGROUND AND PURPOSE: Recent acute stroke trials have reported that intravenous streptokinase is associated with an increased risk of adverse outcomes. We aimed to study the effect of streptokinase on the nature of reperfusion and the relation between reperfusion and clinical outcome. METHODS: We studied 24 patients in the Australian Streptokinase Trial with acute middle cerebral cortical infarction using 99mTc-hexamethylpropyleneamine oxime single-photon emission CT. Eleven of the 24 patients were scanned before therapy and again 24 hours later. The remaining 13 were scanned once either before therapy (1 patient) or after therapy (12 patients). All patients had outcome scans after 3 months. Infarct hypoperfusion was measured with a validated volumetric technique. Neurological impairment and functional outcome were assessed with the Canadian Neurological Scale and the Barthel Index, respectively. RESULTS: Fifteen patients received streptokinase and 9 received placebo. There was no difference in early reperfusion between streptokinase and placebo. However, streptokinase was associated with a greater amount of nonnutritional reperfusion than was placebo (P = .04). This luxury perfusion was associated with poor functional outcome (P = .02). CONCLUSIONS: This study suggests that streptokinase augments luxury perfusion after stroke. Luxury perfusion is associated with a worse outcome, which might be due in part to reperfusion injury.

Adult

Microemboli during carotid angiography. Association with stroke risk factors or subsequent magnetic resonance imaging changes?

BACKGROUND AND PURPOSE: Carotid angiography is associated with a 1% risk of major stroke. Recently, transcranial Doppler ultrasonography (TCD) has shown cerebral microemboli during carotid angiography. To determine their significance, we correlated the number of microemboli during angiography with clinical characteristics, angiography findings, and preangiography and postangiography cerebral magnetic resonance imaging (MRI). METHODS: One middle cerebral artery was monitored with TCD in 24 patients during angiography for carotid territory ischemia. The number of microemboli was correlated with angiographic and clinical characteristics. T2-weighted cerebral MRI was performed before and < or = 48 hours after angiography, and the number of new ischemic lesions was determined in a blinded review. RESULTS: Microemboli were seen in all patients, with an average of 51 per procedure (range, 12 to 154). The majority of microemboli had signal characteristics typical of air. Sixteen of the 24 patients had both preangiography and postangiography MRI. One of 24 patients had an angiographic stroke, with a single new thalamic lesion on MRI. No other patient had a new lesion. The microembolus count correlated with the angiographic contrast volume (P < .001) but not with any other radiological or clinical characteristic. CONCLUSIONS: This study confirmed the presence of numerous cerebral microemboli during carotid angiography. The microembolic signal characteristics and the correlation with contrast volume indicate that introduced air is the cause. These microemboli are usually clinically silent and do not lead to new changes on cerebral MRI.

Adult

Faculty commitment: retaining minority nursing students in majority institutions.

Minority students are at risk in majority institutions. Students face personal, academic, and institutional barriers to their success. Low retention and graduation rates at majority institutions, and particularly in nursing programs, are cause for alarm and compel nursing faculty to take action in order to reverse the trend of under-representation of minorities in the ranks of the profession. Based on the literature and personal experiences, the authors maintain that commitment of both minority and majority faculty is the primary factor in promoting minority student success. Such commitment can lead to increased involvement of faculty in the success of minority students and to the establishment of organized programs and services that facilitate minority student success. Case illustrations are included.

Attitude