PubMed Health⌕ Search

Biomedical subjects

J W Hoekstra

Publications and source records attributed to J W Hoekstra.

28 records · Page 2Linked to original sources
PubMed1985

Effects of long-term catheter implantation on the contractile and histological properties of the canine bladder.

In beagles, a bladder catheter was surgically implanted and subvesical obstruction was artificially introduced. After 3 months a striking reduction in detrusor contractility measured in vitro was observed, which was associated with a presumptive reduction in the concentration of acetylcholinesterase in the muscle cells and a probable reduction in the mean cell size. In this model the contribution of the catheter to the changes is greater than that of the subvesical obstruction.

Acetylcholinesterase↗
PubMed1983

A new method for permanent catheterization in the dog.

A new method of enabling urodynamic measurements to be made in the conscious dog is reported. A connecting device is located under the skin on the dog's back, and a catheter passes between this device and the bladder. The system described has proved valuable.

Animals↗
PubMed1981

Kinetics and mechanism of the oxidation of human deoxyhemoglobin by nitrites.

The reactions of human hemoglobin with sodium nitrite and ethyl nitrite in deoxygenated media have been examined in kinetic detail. Nitrous acid has been identified from kinetic pH dependence studies as the principal oxidant of hemoglobin in reactions with sodium nitrite. Nitrosylhemoglobin is produced concurrently with methemoglobin as a result of reductive release of nitric oxide from nitrous acid. However, oxidation of hemoglobin by nitric oxide competes with association, and this process is proposed to arise from the action of the nitric oxide dimer on hemoglobin. Ethyl nitrite, which serves as a model for nitrous acid, reacts with hemoglobin at rates that are at least 10 times slower than those extrapolated for nitrous acid, and hydrolysis of the alkyl nitrite is not competitive with oxidation of hemoglobin. The composite experimental results are interpreted to describe alkyl nitrite, and, presumably, nitrous acid association with hemoglobin followed by rate-limiting electron transfer resulting in nitric oxide and alkoxide (or hydroxide) production. Proton transfer resulting in alcohol (or water) formation occurs subsequent to the rate-limiting step as do reactions of hemoglobin with nitric oxide.

Hemoglobin A↗
PubMed1981

Oxidation of nitrogen oxides by bound dioxygen in hemoproteins.

Nitric oxide is unique among the higher oxides of nitrogen in its reactivity and efficiency for the oxidation of oxygen-bound hemoproteins. Dinitrogen trioxide serves as a nitric oxide donor, but dinitrogen tetroxide does not exhibit similar reactivity. Details are provided of the stoichiometric transformation through which nitric oxide is converted to nitrate with accompanying oxidation of myoglobin or hemoglobin to the corresponding iron(III) hemoprotein, including an estimate of the rate constant for nitric oxide oxidation of oxygen-associated myoglobin and the effect of unassociated oxygen on the stoichiometry and rates for nitric oxide oxidation. Evidence is presented to establish the mechanism of oxidation in the direct combination of nitric oxide with iron(II)-bound dioxygen.

Animals↗
PubMedDate not supplied

Emergency-department diagnosis of acute myocardial infarction and ischemia: a cost analysis of two diagnostic protocols.

OBJECTIVE: To assess the potential cost savings of the emergency-department (ED) diagnosis of acute myocardial infarction (AMI) and other myocardial ischemia using a nine- hour ED evaluation protocol. METHODS: This one-year study of chest-pain evaluation unit (CPEU) patient charges was undertaken at two midwestern urban university hospital EDs. Included in the study were 447 patients presenting to the EDs with chest pain consistent with myocardial ischemia, nondiagnostic electrocardiograms (ECGs), and stable vital signs. Following initial ED evaluation, CPEU patients underwent nine hours of continuous ECG ST-segment monitoring with serum CK-MB levels determined at zero, three, six, and nine hours. Nonrandomized concurrent chest pain patients with routine ED evaluation and hospital admission without CPEU workup served as controls. At Center 1, patients with negative CPEU evaluations underwent immediate echocardiography (echo) and graded exercise testing (GXT) followed by ED release (CPEU;REL). At Center 2, CPEU patients were released from the ED for outpatient stress thallium testing (CPEU;REL). At Center 2, CPEU patients with positive workups as indicated by elevated CK-MB levels, ischemia by ST-segment monitoring, or positive echo/GXT/ stress thallium testing were admitted to the hospital for further testing. Control patients were admitted directly to the hospital to evaluate for AMI. Hospital charges for CPEU and control groups were compared. RESULTS: (Total charges in dollars, mean +/- SD, student's t-test): [table: see text] CONCLUSION: At both centers, hospital charges related to the acute evaluation of chest pain were significantly lower with this ED diagnostic protocol for AMI and myocardial ischemia.

Adult↗
PubMedDate not supplied

Emergency department CK-MB: a predictor of ischemic complications. National cooperative CK-MB project group.

OBJECTIVE: To demonstrate that a positive CK-MB in the emergency department (ED) predicts an increased risk for complications of myocardial ischemia in patients admitted to the hospital for evaluation of chest pain. METHODS: 53 academic and community hospital EDs participated in this prospective observational cohort analysis of 5,120 patients with chest pain without ST-segment elevation on the initial ED 12-lead electrocardiogram. All patients were admitted for evaluation of chest pain in one of the participating hospitals as part of the National Cooperative CK-MB Project. Patients were stratified by whether or not they had an elevated CK-MB level in the ED. CK-MB measurements were made on ED presentation and two hours later. Patient medical records were reviewed for inpatient diagnoses--myocardial infarction (MI) or other diagnosis--and for ischemic complication--cardiac-related death, recurrent or delayed in-hospital MI, significant ventricular arrhythmias, new conduction defects, congestive heart failure, and cardiogenic shock. RESULTS: 369 (7.2%) of the 5,120 patients had MI. The proportion of patients with any complication in the MI group was 24%, while the complication rate in the non-MI group was 0.4%. In all patients, regardless of final diagnosis, the relative risk of any complication was 16.1 (95% CI 11.0-23.6) in those with a positive ED CK-MB versus negative ED CK-MB patients. Similarly, the relative risk of death was 25.4 (95% CI 10.8-60.2) in positive ED CK-MB versus negative ED CK-MB patients. CONCLUSIONS: Multicenter data support the hypothesis that CK-MB measurements can help risk-stratify ED chest pain patients whose initial ECGs are without diagnostic ST-segment elevation.

Adult↗