Biomedical subjects

K T Kimball

Publications and source records attributed to K T Kimball.

25 records · Page 2Linked to original sources

PubMed1994

Paromomycin for cryptosporidiosis in AIDS: a prospective, double-blind trial.

To test the effects of paromomycin, 10 patients with AIDS and cryptosporidiosis were randomized to paromomycin or placebo in a double-blind trial. After 14 days, patients were switched to the other treatment for 14 additional days. Measures included the number and character of each stool and weekly 24-h stool specimens for weight and oocyst excretion. During the paromomycin treatment phase, oocyst excretion decreased from 314 x 10(6) to 109 x 10(6)24 h (P < .02). Oocyst excretion increased for the 4 patients initially on placebo compared to a median decrease of 128 x 10(6)/24 h for the 6 initially treated with drug (P < .02). Stool frequency also decreased more in those treated with drug (3.6 fewer vs. 1.25 fewer/24 h, P < .05). Trends favored drug over placebo for stool weight, stool character, and Karnofsky score. Paromomycin treatment resulted in improvement in both clinical and parasitologic parameters in cryptosporidiosis in AIDS.

AIDS-Related Opportunistic Infections↗

PubMed1993

Duodenal morphology and intensity of infection in AIDS-related intestinal cryptosporidiosis.

BACKGROUND: The pathogenesis of intestinal cryptosporidiosis is not known. Previous studies have shown that the intensity of infection varies between patients. The hypothesis of this study is that intestinal injury is related to the intensity of infection. METHODS: The histological abnormalities associated with Cryptosporidium infection were evaluated in duodenal biopsy specimens from 18 patients with acquired immunodeficiency syndrome-associated cryptosporidiosis. The intensity of Cryptosporidium infection was assessed histologically in all patients as the percentage of mucosa covered by organisms and by quantitation of oocyst excretion in the stools of 14 patients. RESULTS: Duodenal biopsy specimens from 13 patients (72%) showed normal villous architecture. In these patients, the inflammatory component of the lamina propria was either normal or moderately increased. This increase consisted mostly of lymphocytes and plasma cells. Five of 18 patients (28%) had flattening of the mucosa associated with a prominent neutrophilic infiltrate. The intensity of infection in patients with villous flattening as measured from biopsy specimens and stool was significantly higher than in those without flattening (92% vs. 12% mucosa occupied with organisms; 738 x 10(3) vs. 199 x 10(3) oocyst/mL stool) (P < 0.004 in both cases). CONCLUSIONS: Most patients with intestinal Cryptosporidium infection had normal duodenal villous architecture. Severe duodenal morphological abnormalities, including flattening of the villi, were associated with high-intensity infections.

AIDS-Related Opportunistic Infections↗

PubMed1993

Angiographic and hemodynamic determinants of myocardial ischemia during adenosine thallium-201 scintigraphy in coronary artery disease.

BACKGROUND: Myocardial ischemia attributed to coronary steal may occur in some patients receiving pharmacological coronary vasodilation. ECG ST-segment depression is a marker of myocardial ischemia in these patients, but the factors determining the presence or absence of ischemia are not well known. METHODS AND RESULTS: To examine the angiographic, hemodynamic, and scintigraphic determinants of adenosine-induced ischemic ST-segment depression in patients with coronary artery disease, we studied 65 consecutive patients (45 men and 20 women; mean age, 65 +/- 12 years) who showed reversible perfusion defects during adenosine (140 micrograms.kg-1.min-1 for 6 minutes) 201Tl single-photon emission computed tomography. Patients with prior myocardial infarction were excluded. Ischemic ST depression occurred in one third of the whole cohort (22 of 65 patients). The presence of coronary collateral vessels (p = 0.001), systolic blood pressure at baseline (p = 0.006), and adenosine-induced anginal chest pain (p = 0.011) were the only significant independent predictors of ischemic ST-segment depression by stepwise logistic regression analysis. Rate-pressure product at baseline, systolic blood pressure, heart rate, rate-pressure product, increase in heart rate, and rate-pressure product during adenosine infusion and maximal percent stenosis were variables also significantly related to ischemic ST depression by univariate analysis but were not predictive after the three primary variables were included in the regression model. Perfusion defect size, number of diseased vessels, and age did not correlate with ST-segment depression. CONCLUSIONS: The presence of collaterals, which may predispose to coronary collateral steal, is the most significant correlate of ischemic ST-segment depression during adenosine infusion. Systolic blood pressure at baseline, which may affect the myocardial oxygen supply/demand ratio and anginal chest pain induced by adenosine, are additional variables related to ischemic ST-segment depression during adenosine infusion.

Adenosine↗

PubMed1989

Statistical approach to combining the results of similar experiments, with application to the hematologic effects of extremely-low-frequency electric field exposures.

A large proportion of scientific effort in investigating the possible biological effects of exposure to extremely-low-frequency (ELF) fields consists of laboratory studies on experimental animals. Most experiments in which hematologic properties are measured show no statistically significant effect due to exposure. However, some studies show significant effects which, in general, are not clearly reproducible. A difficult question must then be addressed: Are these relatively few indications of ELF effects statistical artifacts due to the increased risk of a type I error in multiple studies, or is there a real biological effect that is undetected in most studies due to the relatively small sample sizes commonly used? A statistical approach for examining the accumulated results of multiple experiments which results in a single test for treatment effect is presented. The technique requires very mild assumptions, and is valid for experiments that vary widely in specific characteristics such as exposure level, duration, and laboratory. The method is applied to the results of a collection of hematologic and serum chemistry experiments, and the combined results indicate the existence of experimental effects on some end points.

Animals↗

PubMed1980

A rare-male advantage in the housefly induced by wing clipping and some general considerations for Drosophila.

Multiple-choice crosses among five geographic strains of the housefly, Musca domestica L., were carried out in equal (10:10) and low-frequency (4:16) ratios. Initially, a low-frequency-male mating advantage was apparent, but further analyses related this minority advantage to a reduction of male mating success during marking by wing clipping. When there are fluctuating differences in the level of sexual vigor between competing male types over replicate trials of a cross, a mating advantage will accrue to the minority type. Even if males from the two competing strains are equally vigorous, such fluctuating differences will occur during sampling of flies. Harming the flies during marking will serve to enhance this effect and make significant departures toward greater mating success of rare males highly likely. This statistical bias in favor of minority males was substantiated in simulations of the KENCE-BRYANT model of mating success and compared with our results of a minority advantage in the housefly and with published results of a minority advantage in Drosophila. Our evidence, though circumstantial, that an advantage to minority males could have been induced by such an experimental bias suggests that a re-examination of existing data, as well as new experimentation, is necessary to discern whether or not a real rare-male advantage exists.

Animals↗

PubMedDate not supplied

Preoperative risk stratification by adenosine thallium 201 single-photon emission computed tomography in patients undergoing vascular surgery.

BACKGROUND: Adenosine perfusion scintigraphy is a powerful technique for diagnosing coronary artery disease and risk stratifying patients with recent myocardial infarction. METHODS AND RESULTS: We investigated the use of adenosine 201Tl tomography to risk stratify 106 patients undergoing vascular arterial reconstruction consisting of lower limb arterial grafting in 44, aortic aneurysmectomy in 36, and carotid endarterectomy in 26 patients. Abnormal tomograms occurred in 57 patients (54%), 47 (82%) of whom had reversible perfusion defects. There were three postoperative deaths, all in the group that underwent aortic aneurysmectomy. Another patient with an aortic aneurysm had unstable angina and one patient who underwent lower limb arterial surgery had pulmonary edema after surgery. No patient without transient defects had an event (negative predictive value 100%). Cardiac events occurred only in patients with transient perfusion defects. However, only 5 of 47 such patients had events (positive predictive value 11%). The perfusion defect size (23% +/- 14% vs 8.9% +/- 135; p = 0.034) and the ischemic fraction (20% +/- 16% vs 5.6% +/- 8.9%; p = 0.009) were 2.5- and 3.5-fold larger, respectively, in patients with than in those without events. A history of diabetes mellitus or previous infarction did not enhance the predictive value of the test. CONCLUSION: Thus absence of reversible hypoperfusion during adenosine scintigraphy ensures virtual absence of postoperative cardiac events. Patients undergoing aortic aneurysmectomy may be targeted preferentially for risk-stratification strategies in the future.

Adenosine↗

PubMedDate not supplied

Distinct criteria for termination of resuscitation in the out-of-hospital setting.

OBJECTIVE: To identify distinct criteria for appropriate on-scene termination of resuscitation efforts for out-of-hospital cardiac arrest when on-scene interventions fail to restore spontaneous circulation. DESIGN: For 18 months, all out-of-hospital cardiac arrests were evaluated prospectively for survival to hospital discharge and for all established survival predictors including age, gender, presenting cardiac rhythm, whether it was a witnessed event, performance of basic cardiopulmonary resuscitation by bystanders, and interval to paramedic arrival and return of spontaneous circulation (ROSC). SETTING: A large municipality with a single, centralized emergency medical services program. PATIENTS: All normothermic adults treated for out-of-hospital, unmonitored, primary cardiac arrest. INTERVENTIONS: Standard advanced cardiac life support provided at the scene by paramedics. MAIN OUTCOME MEASURES: The number and circumstances of patients achieving survival to hospital discharge following failure to achieve on-scene ROSC. RESULTS: Of 1461 consecutive primary cardiac arrests, 139 were monitored (paramedic witnessed), including 59 that occurred en route to the hospital. Of the 1322 unmonitored patients, 370 achieved ROSC at the scene. Only six (0.6%) of the 952 who did not achieve ROSC at the scene survived, and all six were readily identifiable as having persistent ventricular fibrillation. Excluding those patients with persistent ventricular fibrillation, all survivors achieved ROSC within 25 minutes after paramedic arrival. CONCLUSIONS: Excluding patients with persistent ventricular fibrillation, resuscitative efforts can be terminated at the scene when normothermic adults with unmonitored, out-of-hospital, primary cardiac arrest do not regain spontaneous circulation within 25 minutes following standard advanced cardiac life support. These criteria should now be validated in several large centers with high survival rates.

Aged↗