Biomedical subjects
Publications and source records attributed to D Van Dyke.
In this model, peer review takes place on a nursing department-wide basis within the framework of a preceptor and clinical ladder program. The peer review program is described step-by-step, from planning through evaluation.
At birth, pulmonary vasodilation occurs during rhythmic distension of the lungs with oxygen. Both mechanical and humoral factors are involved, including the release of vasoactive substances such as prostacyclin and endothelium-derived nitric oxide (EDNO). However, the exact mechanisms remain unclear. Because endothelin-1 (ET-1) produces potent pulmonary vasodilation in the fetus via EDNO release and ET-1 concentrations are increased at birth, we considered that ET-1 activity may participate in the pulmonary vasodilation that occurs with O2 ventilation. Therefore, we studied and compared the changes in pulmonary hemodynamics associated with in utero O2 ventilation with and without ET-1 receptor blockade induced by an infusion of Ro 47-0203 (Bosentan, a nonselective ET receptor antagonist), in 13 late-gestation fetal lambs. In all fetal lambs, prostaglandin synthesis was prevented by an infusion of meclofenamate, and ductus arteriosus constriction was prevented by prior formalin infiltration. The infusion of Ro 47-0203 blocked the decrease in pulmonary vascular resistance induced by injections of either ET-1 (-0.985 versus +0.012 mm Hg/mL/min/100 g of lung, p < 0.05) or 4-Ala-ET-1 (an ETb receptor agonist) (-0.717 versus -0.052 mm Hg/mL/min/100 g of lung, p < 0.05). However, ET receptor blockade did not change the increase in pulmonary blood flow or decrease in pulmonary vascular resistance associated with in utero O2 ventilation. This study suggests that endogenous ET-1 activity does not play an important role in the vasodilatory response to ventilation with O2 in utero.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The combination of high-resolution scanning, image-databasing technology and sequence assembly software makes it possible to assemble contiguous overlapping sequences of DNA in a fraction of the time required by manual methods. This paper describes and evaluates an assembly program that rapidly generates contigs from scanned images and provides a unique ability to verify disagreements between overlapping strands or fragments of complementary DNA sequences on-screen, further increasing sequencing throughput.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We studied 53 patients with severe gastrointestinal symptoms thought to be due to a gastric motility disorder. Sixty-six percent had had a previous operation on the stomach, and 21 percent had insulin-dependent diabetes mellitus. Based on clinical, radiographic, and endoscopic findings, 48 patients were thought to have gastroparesis, 3 were thought to have dumping, and 2 had no diagnosis. Measurement of gastric emptying of solids showed that gastric emptying was normal in 12 patients, rapid in 15 patients, and slow in 26 patients. Further evaluation showed that half of the patients with normal gastric emptying, and one third of those with rapid gastric emptying had other diseases of the gastrointestinal tract that responded well to surgery. Of those patients with dumping, diet modification was effective in 40 percent, and half of those who did not respond to dietary manipulations did well after reoperation. Nineteen patients with delayed gastric emptying were treated with metoclopramide. Sixty percent of those without previous gastric surgery responded, whereas only 25 percent of those with previous gastric surgery had good results. The rate of gastric emptying improved following reoperation in 9 (90 percent) of 10 patients with delayed gastric emptying (4 who had not responded to metoclopramide). Gastric emptying was measured again in 15 patients after treatment. The changes after treatment paralleled the clinical response. These studies indicate that gastroparesis cannot be reliably diagnosed on the basis of clinical findings and standard tests. Gastric emptying studies are essential to diagnose and treat patients thought to have gastric motility disorders, and to evaluate the results of therapy.
In 14 patients with Parkinson's disease on long-term therapy the erythrocyte catechol-O-methyltransferase activity was found to correlate with the average plasma concentration ratio of 3-O-methyldopa to levodopa and with the fasting plasma concentration ratio of 3-O methyldopa to levodopa. Patients with the higher erythrocyte catechol-O-methyltransferase activities were those with less favorable clinical responses to levodopa. Since erythrocyte catechol-O-methyltransferase activity may reflect the activity of that enzyme in the major metabolizing tissues, catechol-O-methyltransferase activity would seem to be a significant determinant of response to levodopa.
Explore the source record for details and available documents.
The subject of left ventricular involvement in chronic obstructive airways disease is controversial. We measured left ventricular ejection fraction (LVEF) in 120 patients with severe chronic obstructive airways disease, 92 of them acutely decompensated and 28 stable. A bedside radionuclide technic using a scintillation probe was used to measure LVEF. Of the 28 patients with acute respiratory failure, LVEF was normal (larger than or equal to 55 per cent) in 60 and subnormal in 32. Of the 28 patients with stable chronic obstructive airways disease, LVEF was normal in 12 and low in 16. Coronary artery disease could be demonstrated clinically or at autopsy in 13 of the patients with acute and in 7 of the patients with stable chronic obstructive airways disease. LVEF was 28 plus or minus 10.4 per cent (average plus or minus SEM) in the patients with acute chronic obstructive airways disease and coronary artery disease which was significantly different (P smaller than 0.001) from LVEF in patients without coronary artery disease (61 plus or minus 1.9 per cent). In the patients stable with chronic obstructive airways disease and coronary artery disease, LVEF was (42 plus or minus 3.5 per cent), significantly different (P smaller than 0.001) from LVEF in those without coronary artery disease (55 plus or minus 2.1 per cent). There was no relationship between LVEF and arterial oxygen, or carbon dioxide tension, or pH. Results suggest that LVEF is normal in patients with severe lung disease alone and that reduced LVEF in patients with chronic obstructive airways disease can reasonably be ascribed to coronary artery disease.
Seventeen patients with coronary artery, valvular, or myopathic heart disease were studied to determine correlations of the cardiac output and ejection fraction when comparing the results obtained with a portable probe technique using 113mIn with those obtained with standard methods (cineangiographic, Fick, and dye dilution). With ejection fractions ranging from o.10 to 0.85, the coefficient of correlation was 0.90 when comparing cineangiographic and radionuclide techniques. Cardiac output determinations by the radionuclide technique also correlated well with standard methods (r equals 0.88). The radionuclide method shows promise as an accurate, safe, and simple method in the evaluation of cardiac function at the bedside.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.