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Biomedical subjects

A Pethö

Publications and source records attributed to A Pethö.

8 recordsLinked to original sources
PubMed1989

Influence of diltiazem on postischemic microcirculation and function in the rat kidney.

Renal microcirculation and function were studied in the unilateral clamp-induced ischemia/reperfusion model in anesthetized rats. After 60-min reperfusion fluorochromelabeled globulin was injected i.v. allowing histological determination of capillary plasma flow patterns (CPFP). In the 60-min ischemia protocol the untreated group revealed poor capillary labeling in the outer medulla (OM), whereas cortical perfusion patterns were only slightly altered. Pre- and postischemic treatment with diltiazem led to significant improvement of CPFP in the OM: 4.9% of tissue areas were lying more than 60 microns from the next perfused capillary vs 70.2% after untreated ischemia. Postischemic treatment with diltiazem proved much less effective. Inulin clearance (CIn) amounted to less than 2% of baseline values irrespective of the treatment regimen. However, in the 30-min ischemia protocol, displaying normal CPFP, preservation of CIn was evident and most effective after pre- and postischemic diltiazem treatment (53% vs 8% after untreated ischemia). Measurements of tubular function, however, did not reveal any significant improvement after diltiazem treatment. This observation and the fact that the drugs has a vasodilating effect lend support to the view that the preservation of glomerular filtration rate (GFR) is most likely mediated by vascular mechanisms. In conclusion, in this experimental model diltiazem significantly reduced postischemic disturbances of renal microcirculation occurring after prolonged periods of ischemia and was clearly efficient in maintaining GFR after shorter ischemic episodes; however, tubular function was not preserved. Our results, as well as those of other authors, strongly suggest that diltiazem causes the aforementioned effects mainly by actions at the vascular site.

Animals↗
PubMed1989

Hypoxia-induced acute changes in capillary and fiber density and capillary red cell distribution in the rat heart.

The influence of acute hypoxia (respiration gas 12%, 10%, and 8% O2 and asphyxia, respectively) on 1) the density of perfused capillaries and muscle fibers, and 2) the capillary red cell distribution was investigated in the left heart of anesthetized rats. To observe capillaries and fibers, fluorescein isothiocyanate-labeled (FITC)-gamma-globulin and lissamine-rhodamine-B200-labeled (RB200) myoglobin were injected intravenously as labels of the perfused intravasal and the extracellular space, respectively. The hypoxic conditions were induced subsequently and maintained for 3 minutes. After this period the heart was rapidly frozen for histological demonstration of the dyes. Ventilation with 12% or 10% O2 did not induce any changes in the density of perfused capillaries; however, 8% O2 in respiration gas did lead to a significant increase (capillaries/mm2: subepicardium, 4,180, controls, 3,620; subendocardium, 3,930, controls, 3,240). A similar increase was found in the asphyxia group (capillaries/mm2: subepicardium, 4,170; subendocardium, 3,700). The increases in the density of perfused capillaries were paralleled by rises in fiber density. This leads to the conclusion that the changes in capillary counts were caused by fiber elongation with a resultant decrease in intercapillary distances. This assumption was supported by observations that there were no signs of changes in ventricular segment length during respiration of 12% or 10% O2 but that an increase did occur with 8% oxygen and with asphyxia. Densities of perfused capillaries exactly coincided with anatomical densities (demonstrated by additional labeling of capillary basement membranes with isolectin B4) in normoxic and asphyctic hearts. The distribution of red cells in the capillaries, determined in histological sections, did not differ appreciably under hypoxia due to reduced O2 in respiration air (12%) or asphyxia. The results obtained indicate that 1) extreme hypoxic states cause the capillaries to move closer to each other due to elongation of myocardial fibers and 2) red cell distribution is not altered during these conditions.

Acute Disease↗
PubMed1987

Morphometric investigation of the microvascular system of pancreatic exocrine and endocrine tissue in the rat.

Morphometric data were obtained from the microvasculature in exocrine and endocrine tissue of the rat pancreas. Two groups of anesthetized rats (100 and 300 g body wt, respectively), received intravenous injections of fluorochrome-coupled globulins in order to label the entire vascular system. After circulation of fluorescein-isothiocyanate (FITC)-globulin through the vascular system for 30 min and lissamine rhodamine B 200 (RB 200)-globulin for 5 min, the pancreas was frozen rapidly. In frozen sections of the organ, both dyes showed the same intravascular distribution. The mean number of sectioned vascular elements was 970 +/- 40/mm2 in the exocrine parenchyma and 1430 +/- 60/mm2 in islet tissue. The cross-sectional area fraction of the microvascular system, which is equivalent to the intravascular volume fraction, amounted to 0.027 +/- 0.001 mm2/mm2 in the exocrine system and to 0.061 +/- 0.002 mm2/mm2 in the endocrine pancreas. The corresponding values for microvascular surface area (mm2/mm3) were 18.0 +/- 0.8 (exocrine tissue) and 34.2 +/- 2.0 (endocrine tissue). Mean diameters of vessels up to 10 microns in exocrine tissue amounted to 5.5 +/- 0.2 and 6.1 +/- 0.1 microns in exocrine and endocrine tissues, respectively; when all vessels up to 30 microns in diameter were considered, these values amounted to 5.7 +/- 0.2 and 6.7 +/- 0.2 microns, respectively. Especially in light of the fact that flow rate was observed to be much higher in islets than in acini, the present results support the existence of an insular microcirculatory system which is specialized in terms of its exchange capacity.

Animals↗
PubMed1986

The role of upstream sequences in determining the strength of an rRNA promoter of E. coli.

In vitro transcription experiments were carried out with recombinant plasmids containing the promoters of the rrnB gene of Escherichia coli, and with deletion mutants lacking various lengths of the AT-rich sequence upstream from the P1 promoter of that gene. The main conclusions are as follows: The in vitro transcriptional activity of the P1 and P2 promoters of the rrnB gene are an order of magnitude higher on closed-circular (supercoiled) templates than on linear DNA; the strong P1 and P2 promoters are heparin-sensitive on linear templates, and on circular DNA only P2 is heparin-resistant; removal of the upstream AT-rich region did not decrease the apparent in vitro strength of the P1 promoter under standard conditions (50 mM KCl, high RNA polymerase/DNA ratio); at higher salt concentrations, or with a lower RNA polymerase/DNA ratio, the deletion mutants displayed much lower in vitro transcriptional activity than the wild-type, and the apparent weakening of the P1 promoter was roughly proportional to the length of the deleted AT-rich sequence. The implications of these findings for the possible in vivo role of the AT-rich region are discussed.

Base Sequence↗
PubMed1986

Distribution of capillary blood flow in rat kidney during postischemic renal failure.

Changes in distribution of intrarenal blood flow were studied in anesthetized rats during the acute phase of postischemic renal failure (1 h renal artery occlusion, 1 h reflow). Distribution of capillary plasma flow was determined by injecting fluorescein-isothiocyanate-globulin and lissamine-rhodamine-B200-globulin 1, 3, or 10 min prior to rapid freezing of the kidney. In histological sections it was possible to differentiate among the vessels perfused during the time of labeling because of their respective fluorescence. In these experiments all glomeruli became labeled within 1 min, although in contrast to the controls, the glomerular capillary network itself was not filled completely in the postocclusion organs. Incomplete labeling was far more pronounced, however, in the postglomerular network of the occlusion experiments. Due to this effect in the cortex and in the medulla, 11 and 58% of tissue, respectively, were found lying at a distance of more than 60 microns from the next vessel labeled after 1 min of dye circulation. In the control experiments there was no tissue within this distance. Prolonging the time of labeling up to 10 min caused little change in this pattern of distribution. In the occlusion experiments, the globulins were observed in nearly all Bowman spaces, but in less than half of the tubular lumina. The results strengthen the view that the ischemic insult leads primarily to disturbance of the postglomerular perfusion, which then results in trophic damage of the tubular system mainly within the renal medulla.

Acute Kidney Injury↗
PubMed1984

[Follow-up treatment of vaginal hysterectomies using a bensopyrone preparation. Single-blind study on the subject of prevention of disorders of wound healing].

In a single blind study a benzopyrone drug proved efficient in the treatment of wound healing disorders following vaginal hysterectomy. The verum group (n = 60) had less symptoms and signs as rubor , edema, flux, pain, adnexitis etc. than the control (n = 60). The formation of keloid was very rare, micturition difficulties were missing, and the "second catheterization", generally practised, was very seldom needed. The mode of action of the drug is described.

Clinical Trials as Topic↗
PubMed1981

[Efficacy of benzopyrones in posttraumatic inflammations/Clinical double blind study in the postoperative treatment of episiotomy (author's transl)].

A clinical double-blind study of the effectiveness of the benzopyrone product 5.6-benzo-alpha-pyron + 3',4',7-tris-(hydroxy-ethyl)-rutin (coumarin + troxerutin, Venalot) was investigated in 560 patients following medio-lateral episiotomy. The compound was investigated at various dose levels, and its active components coumarin and troxerutin separately. It was shown that the symptoms of posttraumatic inflammation like edema, rubor around the incision wound, and posttraumatic pain as well as consumption of analgesics and the postoperative scar formation were beneficially influenced by the drug. As a guideline for dosing, 1 mg/kg/d related to the coumarin content, was calculated. The efficacy of the combination of the active compounds was superior to that found with the components applied separately. The significance of episiotomy as clinical model for posttraumatic inflammation in general is discussed and application of the benzopyrone product above all in plastic surgery is suggested.

Adolescent↗