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Biomedical subjects

J Amend

Publications and source records attributed to J Amend.

7 recordsLinked to original sources
PubMed1996

Systemic responses to SFHS-infusion in hemorrhaged dogs.

Anesthetized mongrel (weight range: 16-27 Kg) dogs were prepared for monitoring hemodynamics, blood flow distribution, plasma colloid osmotic pressure and renal functional parameters at various intervals. Removal of 35 ml/Kg blood resulted in marked drop and only partial spontaneous recovery in systemic and pulmonary arterial pressures, cardiac output and organ blood flows (> 50% flow-decrements occurred in kidney, spleen, heart, gut and pancreas); plasma colloid osmotic pressure as well as urine output and creatinine clearance also fell. Group I (n = 6) of dogs was transfused after 45 minutes of hypovolemia with their own anticoagulated blood, while Group II (n = 6) received an equal volume of unmodified 6% stromafree hemoglobin solution (SFHS). Comparison of the two groups' responses to resuscitation yielded some differences. There was a significant overshoot (30 mmHg) in systemic arterial blood pressure accompanied by bradycardia in Group II only. Cardiac output recovered in both groups but was less well sustained in Group II. Cerebral blood flow rose higher and hepatic arterial flow-increment was less in Group II than in Group I; the responses to resuscitation in the other organs were comparable. Colloid osmotic pressure decreased in Group I whereas it rose immediately after resuscitation in Group II, declining thereafter with a converging trend and 30 minutes thereafter the differences were not significant between the groups. Urine excretion and creatinine clearance recovered to comparable extents in both groups, but N-acetyl-beta-D-glucosaminidase (N.A.G.) excretion rose over 10-fold higher in Group II than in Group I. These experiments have defined the response of bled animals to resuscitation with unmodified, unpurified SFHS, when compared to resuscitation with whole blood, showing a less well sustained but adequate hemodynamic and renal functional recovery while revealing indications of early renal tubular cellular injury, providing baseline comparison for testing highly purified and modified hemoglobin solutions.

Animals↗
PubMed1995

Coronary artery bypass grafting after failed coronary angioplasty: risk factors and long-term results.

In this case-control study we investigated the preoperative risk factors and long-term results in patients undergoing emergency coronary artery bypass grafting (CABG) after failed percutaneous transluminal coronary angioplasty (PTCA). From January 1990 to March 1993, 56 emergency CABGs (Group A) were performed in patients from 7 different cardiology centres--six of these located outside our hospital within a radius of 19 km-1 h to 114 h (phi 7.3 h) after failed PTCA. No special stand-by was given and patients were operated in the next available theatre. Criteria of anatomically unfavourable stenoses for PTCA were defined as follows: Long stenoses, occlusions of other major vessels, tandem stenoses, stenoses at or near a bend or branch and, finally, eccentric stenoses. Thirty-two percent met one criterion, 35.8% two, 6.9% three and 1.8% four criteria. All patients were examined echocardiographically 14.6 +/- 8.2 months postoperatively. Patients who had been operated on electively within the same period served as a control (Group B; n = 56; case-control study). The patients were matched for age, sex, EF, LVEDP, body surface area, reoperation status, and concomitant diseases. The mortality rate for Group A patients was 10.7% (n = 6); for Group B, 1.8% (n = 1). Five of the Group A patients who died came from our own hospital and only one from a hospital 1 km away (mortality: 14.3% vs. 4.8%). There were no deaths among patients with an anatomically favourable stenosis for a PTCA; in patients with more than one criterion for an unfavourable stenosis mortality increased to 19.0% (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1995

Use of the internal mammary artery as a graft in emergency coronary artery bypass grafting after failed PTCA.

The use of the internal mammary artery (IMA) is recommended in elective aorto-coronary bypass grafting (CABG) because of favourable long-term patency results. In emergency CABG many surgeons prefer revascularization only with venous grafts due to the shorter operation time and higher initial flow rates of this type of graft. We investigated whether use of the IMA influences operative and mid-term results of emergency CABG after failed percutaneous transluminal coronary angioplasty (PTCA). From January 1990, to March, 1993, 56 emergency CABGs were performed in patients from 7 different cardiological centres where PTCA had failed. In 23 patients (Group A), the IMA was used as a bypass graft. In most of these patients the left IMA was anastomosed with the left anterior descending artery (n = 19). In one case both IMAs were used as bypass grafts. Venous grafts only were applied in 33 patients (Group B). Due to preparation of the IMA, aortic cross-clamp and bypass times were approximately 15 mins longer in Group A patients, although there was no significant difference in the number of grafts (1.7 +/- 0.8 in Group A vs. 1.5 +/- 0.7 in Group B). All patients of Groups A and B underwent echocardiographical investigations 14.6 +/- 8.2 months postoperatively. The overall mortality in Group A was 13% (n = 3) compared to 9% (n = 3) in Group B (p = 0.58). Significant predictors for death were age 65 years and over, diabetes mellitus, dilatation of the RCX and stenoses unfavourable for PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1978

Quantum yield and image contrast of bacteriochlorophyll monolayers in photoelectron microscopy.

The photoelectron quantum yield spectrum of bacteriochlorophyll aGg (Bchl a ) from Rhodospirillum rubrum was determined in order to evaluate the possibility of mapping photoreceptor distribution and organization in bacterial chromatophores. The quantum yield is on the order of 1 X 10(-3) electrons/incident photon at 180 nm and decreases to 2.5 X 10(-5) electrons/incident photon at 230 nm. Photoelectron micrographs confirm the high contrast predicted between monolayers of Bchl a against a lipid background (calcium arachidate). A significant contrast difference is found between the two monolayer orientations, demonstrating that photoelectron microscopy is a sensitive detector of asymmetry in Bch1 a monolayers.

Bacteriochlorophylls↗
PubMed1976

Systolic time intervals in induced atrial fibrillation in the dog.

The effect of induced atrial fibrillation on ventricular performance in the dog as measured by changes in the systolic time intervals (STI), was investigated. Atrial fibrillation was induced by enhancement of vagal tone with morphine sulfate, followed by direct mechanical stimulation of the atrium. Dogs received 15 mg. per kilogram of morphine sulfate subcutaneously, followed by 3 mg. per kilogram of pentobarbital sodium. ECG, atrial electrogram, phonocardiogram, and direct arterial blood pressure were recorded during periods of sinus rhythm and during periods of induced atrial fibrillation. Data were analyzed by selecting 20 representative cardiac cycles from each condition in each of 15 dogs. Cycles were selected so that the broadest spectrum of rates was examined for each animal. Three hundred cycles were examined from each condition, or a total of 600 cycles. Heart rate (HR), left ventricular end-diastolic pressure, and aortic end-diastolic pressure were unchanged during atrial fibrillation. The left ventricular pre-ejection period (LVPEP), externally derived isovolumic contraction time (EICT), and total mechanical systole (S1-S2 interval) were all found to increase significantly in duration after the induction of atrial fibrillation. The left ventricular ejection time (LVET) and the electromechanical delay (Q-S1 interval) were significantly decreased in duration following the induction of atrial fibrillation.

Animals↗