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Biomedical subjects

G Hutchins

Publications and source records attributed to G Hutchins.

8 recordsLinked to original sources
PubMed1992

Correlation of the complete version of the Selvester QRS scoring system with quantitative anatomic findings for multiple left ventricular myocardial infarcts.

The correlation between myocardial infarct size estimated by the complete version of the Selvester QRS scoring system and that documented by pathoanatomic studies has been reported for single anterior, inferior and posterolateral infarcts. Although previous studies described electrocardiographic changes in patients with multiple infarcts, no quantitative documentation of the ability of such changes to estimate the total amount of left ventricular infarction has been reported. This study of 32 patients with anatomically documented multiple infarcts shows a significant correlation between QRS-estimated and anatomically documented sizes (r = 0.44; p = 0.01), which is less than that previously reported for single infarcts in the anterior, inferior and posterolateral locations. Several of the 54 electrocardiographic criteria were never satisfied. Criteria for posterior infarction were seldom present, suggesting "cancellation effect" of coexisting anterior infarction. These results will be the basis for future modification of QRS criteria for estimating myocardial infarct size.

Adult↗
PubMed1991

Imaging of renal cancer using positron emission tomography with 2-deoxy-2-(18F)-fluoro-D-glucose: pilot animal and human studies.

The feasibility of imaging renal cancers with 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) and whole-body positron emission tomographic scanning was assessed in nude mice with human renal adenocarcinoma xenografts and then in 5 patients with primary renal cancer (4 adenocarcinomas and 1 transitional cell carcinoma). In nude mouse biodistribution studies tumor FDG uptake was maximal at 0.33 to 2 hours but tumor-to-blood ratios increased continuously to 7.8/l. by 4 hours after intravenous FDG injection. In all 5 patients primary and metastatic tumors were imaged within 1 hour by FDG positron emission tomography following intravenous injection of the FDG. By contrast, an hepatic hemangioma did not accumulate FDG. In summary, FDG metabolic and anatomical imaging of primary and metastatic renal cancer is feasible and in these pilot studies appears to be a promising imaging methodology that may be further enhanced by delayed imaging times. Additional study in a larger number of patients is essential to define better the accuracy and potential clinical use of this method.

Adenocarcinoma↗
PubMed1991

Quantitative evaluation of regional substrate metabolism in the human heart by positron emission tomography.

Meaning interpretation of metabolic images obtained by positron emission tomography for evaluation of cardiac disease requires a knowledge of the normal variation in regional myocardial substrate metabolism. Recent studies with fluorine-18 (F-18) fluorodeoxyglucose suggest inhomogeneity of myocardial glucose metabolism in the normal human heart, which may relate to substrate availability. Therefore, quantitative evaluation of myocardial oxidative metabolism and glucose metabolism, as derived by dynamic positron emission tomography with carbon-11 (C-11) acetate and F-18 fluorodeoxyglucose, was performed in nine healthy male volunteers. All were studied under tightly controlled metabolic conditions of hyperinsulinemic-euglycemic clamping with and without a concurrent lipid emulsion infusion. Significant inhomogeneity of regional glucose metabolism was noted although it was less than that described under fasting conditions. Glucose utilization was 13% lower in the septum compared with the lateral wall both without and with lipid infusion (0.34 vs. 0.39 mumol/g per min, respectively, p less than 0.05; and 0.33 vs. 0.38 mumol/g per min, respectively, (p less than 0.05). Relatively decreased septal glucose utilization could not be explained by decreased metabolic demand because C-11 clearance constants were marginally higher in the septum than in the lateral wall in both studies (0.055 vs. 0.054 per min, respectively, p = NS; and 0.061 vs. 0.056 per min, respectively, p less than 0.05). Relatively decreased septal glucose utilization could reflect regional variation in substrate use and possible preferential free fatty acid utilization by the septum. These data provide a useful framework for assessing altered cardiac metabolism in disease and support standardization of metabolic conditions during metabolic imaging with positron emission tomography.

Acetates↗
PubMed1990

Effect of regional myocardial ischemia on sympathetic nervous system as assessed by fluorine-18-metaraminol.

With the introduction of radiolabeled catecholamine analogues, the noninvasive evaluation of the cardiac sympathetic nervous system has become possible. This study evaluated the effect of regional ischemia on myocardial retention of the new norepinephrine analogue 6-[18F] fluorometaraminol (FMR) in the open chest dog model. Six dogs were injected intravenously with FMR following 30-min occlusion of the left anterior descending artery. Six sham animals served as control group. Regional myocardial blood flow as determined by microspheres decreased 87% during ischemia (p less than 0.01), but was not significantly different from control myocardium following reperfusion. Regional myocardial 18F activity as determined postmortem was significantly reduced in reperfused myocardium (-34%), which paralleled an 18% reduction of tissue norepinephrine concentration. Thus, short time periods of coronary occlusion affect neuronal function indicating the sensitivity of the sympathetic nerve terminals to ischemia. FMR provides a new tracer approach for the characterization of neuronal integrity in postischemic myocardium.

Animals↗
PubMed1979

The pregnant Syrian hamster as a model to study intravascular trophoblasts and associated maternal blood vessel changes.

In pregnant Syrian hamsters (Mesocricetus auratus) used as an animal model for studying the migration of fetal trophoblasts and the associated changes in maternal blood vessels, intravascular trophoblasts migrated well beyond the blood vessels of the uterus and into the vessels of the mesometrium. They migrated beyond the decidua of the uterus, into the lumina of maternal uterine and mesometrial arteries, but not into veins. The arterial changes, which were often segmental, resembled those seen in the decidua and consisted of a replacement of normal smooth muscle cells by poorly differentiated stromal cells. Ultrastructurally, the trophoblasts were either above or below maternal endothelial cells. They occurred also as single or multiple layers within the lumina of arteries that lacked an endothelial lining. Apparent penetration of the elastic membrane by the fetal trophoblasts brought them into close apposition to maternal cells in the arterial wall. Histochemical studies showed heightened metabolic activity of the intravascular trophoblasts as suggested by strong histochemical reactions to nonspecific esterase, succinic dehydrogenase and the glycerophosphate dehydrogenase reactions. Thus, these metabolically active fetal trophoblasts actively migrate into the maternal arterial system, resulting in loss of endothelial cells and changes in the wall of the maternal arteries similar to those in the decidua at the uteroplacental junction.

Animals↗
PubMed1975

Vascular interdependence in postmortem human lungs.

Interdependence of arteries and the surrounding lung was estimated in excised, postmortem human lungs. At low vascular pressures, vessel diameter increased as the lung was inflated. At high vascular pressures, vessel diameter decreased as the lung was inflated. Compared to the effects of interdependence in excised dog lobes, those in human lungs at low transpulmonary pressures were small. The following conclusions were reached: (1) the diameter of intrapulmonary arteries is stabilized (more constant with changes in intravascular pressure) when the lung has a high transpulmonary pressure; (2) increases in pulmonary vascular resistance at high lung volumes may be related to extra-alveolar, as well as intra-alveolar, vessel compression; (3) interdependence in human lungs differs markedly from interdependence in dog lungs.

Adolescent↗
PubMedDate not supplied

Successful four-hour heart-lung preservation with core-cooling on cardiopulmonary bypass: a simplified model that assesses preservation.

This study was done to determine whether core-cooling could provide extended cardiopulmonary preservation and if reimplantation could be simulated and evaluated in the ex vivo autoperfused working heart-lung model. Twenty calves were divided into four groups and placed on cardiopulmonary bypass and rapidly cooled to 15 degrees C. Control heart and lungs were harvested after administration of cardioplegia through the aortic root and were subsequently resuscitated in the autoperfused working heart-lung circuit (group 1) or were orthotopically allotransplanted (group 2). Preserved heart and lungs were similarly excised but stored in a normal saline solution bath at 4 degrees C for 4 hours and then were resuscitated in the autoperfusion circuit (group 3) or were orthotopically allotransplanted (group 4). All groups received isoproterenol during explantation and reperfusion and were studied for 4 hours. Myocardial function was assessed by sonomicrometric techniques, and pulmonary preservation was evaluated by measurements of extravascular lung water, arterial oxygen tension on 100% inspired oxygen, and pulmonary vascular resistance. Cardiorespiratory function after 4-hour static preservation was similar in all four groups except that the arterial oxygen tension in group 1 was lower compared with group 3. Core-cooling on cardiopulmonary bypass without pulmonary artery flushing results in cold ischemic heart-lung preservation, comparable to other currently used modalities. In addition, reperfusion in the ex vivo autoperfusion circuit provides a simplified model to assess the adequacy of cardiopulmonary preservation techniques.

Animals↗