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R M Bohle

Publications and source records attributed to R M Bohle.

80 records · Page 5Linked to original sources
PubMed1991

Failure of iloprost to protect the regionally ischemic, reperfused porcine heart.

The effect of iloprost (Schering AG, Berlin), a stable prostacyclin analogue, was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery (LAD) was distally occluded in 18 pigs for 45 min followed by 3-d of reperfusion. Nine pigs were continuously treated with iloprost at a dose of 25 ng/kg per min. Treatment was started as intracoronary infusion into the proximal LAD 10 min before occlusion. The intercoronary infusion was replaced by an intravenous infusion after 45 min of reperfusion, which was continued until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Myocardial concentrations of adenosine triphosphate were evaluated at the end of the experiment. Generation of free radicals by stimulated polymorphonuclear neutrophils was determined by luminol-enhanced chemiluminescence. Histologic and immunohistologic techniques were applied to characterize the myocardial inflammatory response. Global hemodynamics did not differ between the two groups. Neither infarct size (control group 68 +/- 18%, treated group 74 +/- 14%), recovery of systolic shortening (control group 3 +/- 6%, treated group 6 +/- 6%), nor myocardial adenosine triphosphate concentrations were improved by iloprost treatment. Myocardial inflammatory response remained unaffected by this treatment. The capacity of coronary venous, stimulated polymorphonuclear neutrophils to generate free radicals was slightly suppressed in the treated group before ischemia, at the end of ischemia and during early reperfusion. In this preparation, iloprost did not exhibit any beneficial effect on infarct size, recovery of systolic shortening and myocardial adenosine triphosphate concentrations.

Adenosine Triphosphate↗
PubMed1991

Modulation of the inflammatory response in experimental myocardial infarction.

The role of inflammation in reperfused, ischaemic myocardium was assessed morphologically in 39 porcine hearts after 24 h (n = 23) and 72 h (n = 16) of reperfusion and after different antiphlogistic treatments. The left anterior descending coronary artery (LAD) was occluded distally for 45 min. Seven pigs received BW755C (10 mg kg-1) i.v. prior to ischaemia (A), eight pigs were given the same dose before 24 h of reperfusion (B), and eight pigs were treated with iloprost (25 ng kg-1 min-1) i.v. before occlusion and continuously for 72 h (C). Two groups of eight pigs each served as controls for 24 h (D) and 72 h (E) of reperfusion. Infarct sizes were determined, myocardium was investigated by light microscopy, and polymorphonuclear leucocytes (PMNs) and macrophages were quantitated after histo- and immunohistochemical staining. Jeopardized myocardium contained 129 neutrophils mm-2 and 120 macrophages mm-2 (D) vs 10 neutrophils mm-2 and 290 macrophages mm-2 (E). Neutrophils and infarct sizes were only significantly decreased in group A (68 neutrophils mm-2, 30% reduction of infarct size). Macrophages infiltration was not significantly affected for all treatment groups (A, B, C). It is concluded that myocardial infarct sizes are neutrophil-mediated postischaemic tissue injury can be reduced by BW755C applied prior to ischaemia. Neutrophil-mediated myocardial injury is unlikely to occur beyond 3 days of reperfusion.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1988

Antiinflammatory agent BW 755 C in ischemic reperfused porcine hearts.

The effect of the antiinflammatory compound BW 755 C on myocardial infarctions was evaluated in regionally ischemic reperfused hearts of 35 pigs. The left anterior descending coronary artery was occluded distally in 23 anesthetized pigs for 45 min and was reperfused for 24 h. The BW 755 C (10 mg/kg) was intravenously injected prior to ischemia in seven pigs (group A). A second dose of BW 755 C (5 mg/kg) was given after 4 h of reperfusion. Group B consisted of eight animals. They were treated with BW 755 C immediately before (10 mg/kg i.v.) and after 4 h of reperfusion (5 mg/kg). Another eight pigs served as controls. At the end of the experiments, infarct size was determined as the ratio of the infarcted myocardium (tetrazolium stain) over the risk region (fluorescent dye). Leukocyte infiltration of the risk region was histologically quantitated in one slice of each experiment. In a second set of experiments recovery of regional myocardial function of the risk region was determined by sonomicrometry during 2 weeks of reperfusion. The BW 755 C (10 mg/kg) was injected intravenously in six pigs before ischemia and at a dose of 5 mg/kg after 4 h of reperfusion. Six pigs served as controls. Hemodynamic parameters and total leukocyte blood count did not differ between the groups. Treatment protocol of group A reduced the infarct size from 72 +/- 13% (control group) to 50.9 +/- 12% (p less than 0.005). Infarct size of group B (65 +/- 16%) did not differ from control experiments. Leukocyte infiltration of the risk region was only attenuated in group A (p = 0.01) compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1986

Morphology of healing in vascular prostheses.

Vascular grafts differ in shape and size, material, mode of construction, and porosity. The latter was found to be of great importance with respect to tissue response of the host to the graft. The first reaction of the host after implantation represents the phase of exsudation. An aggregate of platelets and fibrin will cover most of the luminal and external surface of the graft, which is also seen between the interstices. The following phase of resorption develops within 2 weeks. It is characterized by replacement of the fibrinous material on the outer surface and between the interstices by capillaries, histiocytes, and myofibroblasts. Organisation of the outer capsule will then occur, and is also seen inside the transprosthetic bridges within one month. However, organization of the luminal lining remains very slow and is almost never completed. Healing depends on blood flow and local hemodynamic factors, and a mismatch in mechanical properties between the graft and host vessel may be important. Sources of endothelium in graft healing are anastomotic sites, pluripotent cells growing through the graft wall or deposition of pluripotent cells from the blood. Early failure of a prosthetic vascular graft occurs mainly as a result of separation at its sites of attachment. Late complications may be the result of mechanical failure (anastomotic sites or within the graft), kinking, inadequate or incomplete healing, and infection. The incidence of infectious complications varies from 0.25% to 6.0%, usually associated with high mortality rates.

Animals↗
PubMed1984

Adaptation and decompensation of intrarenal small arteries in experimental hypertension.

In the presence of hypertension, the arterial and arteriolar vessel walls may undergo adaptive, destructive, and reparative changes. These different types of hypertensive alterations were studied simultaneously in the intrarenal vascular bed of two-kidney, one-clip hypertensive rats. After constriction of one renal artery, focal medial necrosis of the interlobular arteries developed in the untouched kidneys after the first 24 h. These earliest signs of vascular decompensation could be explained by short-lasting hypertensive episodes that were only detectable by continuous blood pressure recording in conscious animals. Two weeks after the experiment was started, owing to a widening of the media, a substantial increase in the wall-to-lumen ratio was observed in the interlobular arteries. At the same time, the frequency of focal medial necrosis began to fall significantly. Therefore we concluded that the structural vascular adaptation might be responsible for the disappearance of focal medial necrosis in spite of still rising blood pressure values. This assumption was confirmed by an additional experiment in previously chronically two-kidney, one-clip hypertensive rats: 24 h after removing the renal artery clip, a short, severely hypertensive period, induced by infusions of angiotensin II, caused hypertensive vascular lesions almost exclusively in the primarily clipped kidneys with a nonadapted vascular bed. Early intimal changes, which are known to lead to malignant nephrosclerosis, were not only absent in the beginning of two-kidney, one-clip hypertension, but also did not occur during the angiotensin-induced accelerated hypertension. Thus, even extremely high blood-pressure values per se may not be enough to initiate this crucial renal vascular disease.

Adaptation, Physiological↗
PubMed1982

Contrasting renal effects of different antihypertensive agents in hypertensive rats with bilaterally constricted renal arteries.

Systemic and renal effects of the vasodilators dihydralazine and minoxidil were compared with those of the converting-enzyme inhibitor captopril (SQ 14225) and the AII antagonist sarisoleucin (Sar1Ile8-AII) in chronically sodium-depleted, two-kidney, two-clip hypertensive rats. Arterial blood pressure normalized in all experimental groups within 24 hours and remained normal until the end of the experiment. By day 4, plasma concentrations of creatinine and urea in animals treated by captopril or sarisoleucin were significantly higher than those measured after the administration of dihydralazine or minoxidil. Renal tubular lesions were also more frequently observed after the renin-angiotensin system (RAS) was blocked than they were after vasodilatation was induced by direct smooth muscle relaxation. Captopril and sarisoleucin stimulated the RAS more extensively than dihydralazine and minoxidil did. The results indicate that, in the presence of bilateral renal artery stenosis and sodium deprivation, systemic blood pressure normalization after the blockade of the RAS may be accompanied by acute renal failure. This may be explained partially by poststenotic renal hypotension, but it may also reflect a reduction of the GFR because of the blockade of intrarenal actions of AII.

Animals↗
PubMedDate not supplied

Intrarenal arteries in rats with early two-kidney, one clip hypertension.

Structural arterial adaptation and decompensation were studied in the contralateral untouched kidneys of two-kidney, one clip hypertensive rats 1 to 64 days after constricting one renal artery. Focal necroses of intrarenal arteries were observed as early as 24 hours after starting the experiment. The necroses reached their maximum on Day 8 and thereafter decreased significantly in spite of still increasing blood pressure values. After 8 days the media thickness of the interlobular arteries was significantly increased by more than 30% and remained so until the end of the experiment. Blood pressure levels as measured by tail plethysmography were nearly normal within the first 4 days. The continuous 24-hour blood pressure recording in the conscious rats, however, showed shortlasting intermittent hypertensive spikes as early as 6 hours after renal artery constriction. In spite of these acute hypertensive peaks, which frequently exceeded 200 mm Hg, intimal lesions, potentially leading to malignant nephrosclerosis, began to appear after only 2 weeks. Thus, the development of nonobliterating, acute focal necroses of intrarenal arteries in the earliest stage of two-kidney, one clip hypertension may be explained by intermittent hypertensive episodes accompanied by a segmental overstretching of the nonadapted vascular bed. On the other hand, the occurrence of obliterating malignant nephrosclerosis in the presence of severe hypertension may also depend on the previously changed composition of the vessel walls.

Animals↗