Search PubMed⌕ Search

Biomedical subjects

H Kritz

Publications and source records attributed to H Kritz.

At least 55 records · Page 3Linked to original sources
PubMed1996

Imaging of atherosclerosis (Part II).

Several methods are currently used to detect and quantitate atherosclerosis. Standard methods like angiography, computed tomography and sonography are described in part I of this paper. Angiography, still considered to be the "gold standard" to detect atherosclerotic lesions is invasive, involves potential risks for the patient and cannot be used in asymptomatic subjects even though they may be at high risk to develop atherosclerosis. Computed tomography and sonography are suitable to define morphological alterations of atherosclerotic lesions, but they are unfit to characterize their functional stage. Functional methods such as scintigraphy (planar and single-photon-emission tomography), positron emission tomography, and magnetic resonance imaging (reviewed in Part I) partly fulfil the claim to image early atherosclerosis. Preliminary evidence indicates that radioisotopic techniques and magnetic resonance imaging may be of great benefit in the future for elucidating functional aspects of this widespread disease. The functional diagnostic procedures available today are reviewed in this paper.

Animals↗
PubMed1996

Passive smoking, platelet function and atherosclerosis.

Active smoking is a well known risk factor for the development of atherosclerosis and in particular coronary heart disease and peripheral vascular disease. The negative effects of active smoking demonstrated on platelet function, the eicosanoid system and platelet thromboxane A2 generation may contribute to the hemostatic imbalance reported. Recently, the problem of passive smoking as a health risk has been widely discussed. Detailed information on the role of passive smoking on hemostatic parameters, however, is still very limited. As far as present knowledge is concerned, platelet activation seems to be significantly involved in the deleterious vascular effects of passive smoking as well.

Arteriosclerosis↗
PubMed1996

[Single passive smoking exposure induces no measurable oxidation of low density lipoproteins].

Oxidation of low-density lipoproteins (LDL) is well known to increase the atherogenic risk. Active smoking has been claimed to be associated with a significant oxidant stress determined by enhanced LDL oxidation and isoprostane formation. We assessed the susceptibility of LDL to oxidation in 9 healthy non-smokers and 7 smokers before and after three and five hours' exposure to passive smoking. Baseline values for the lag time, diene formation, malondialdehyde and isoprostanes differed in part significantly. In contrast to the data on active smoking, passive exposure to cigarette smoke did not significantly affect any of these parameters, nor diene formation and electrophoretic mobility in smokers and non-smokers alike. These results indicate that a single exposure to passive smoking does not induce relevant oxidation of LDL in men.

Adult↗
PubMed1995

Isradipine increases vascular prostaglandin I2-formation while the thromboxane B2-synthesis is diminished.

PGI2- and TXA2-synthesis from vascular tissue samples derived from cultured (endothelial and smooth muscle) cells, rabbit aorta and human bypass surgery were determined using specific radioimmunoassays for the stable derivatives (6-oxo-PGF1a and TXB2, respectively) of these compounds. Cultured cells were incubated in presence of isradipine, rabbits were pretreated for 4 weeks receiving 0.3 mg isradipine/kg*day, while patients were on isradipine (5-10 mg total dose/day, per os twice daily) since 6-19 weeks. In presence of isradipine, cultured cells produced significantly (p < 0.01) more 6-oxo-PGF1a and significantly less TXB2 (p < 0.05). 6-oxo-PGF1a-formation in rabbit aorta was significantly (p < 0.01) higher in isradipine treated normocholesterolemic animals while no significant changes were seen in isradipine treated hypercholesterolemic animals. TXB2 was significantly (p < 0.01) depressed in the abdominal and the thoracic aortic segment of isradipine treated hypercholesterolemic animals and was not significantly influenced in isradipine treated normocholesterolemic animals. Similarly, PGI2-synthesis in human arterial specimen was significantly (p < 0.01) enhanced as compared to the untreated controls. These findings indicate a beneficial behaviour of isradipine on vascular wall eicosanoid profile, which may contribute to a variety of antiatherosclerotic actions at the vascular wall level and to an improvement in hemostatic balance already described.

Aged↗
PubMed1995

Passive smoking and cardiovascular risk.

A possible relationship between passive smoking and coronary heart disease has been widely debated during the past decade. Convincing evidence links environmental (passive) tobacco smoke exposure to heart disease morbidity as well as mortality. In the United States, 37,000 coronary heart disease deaths per year are attributed to environmental tobacco smoke exposure, accounting for 70% of all deaths caused by environmental tobacco smoke. The analysis of 10 epidemiologic studies indicated a consistent dose-response effect related to exposure, but more proof is still needed. Evidence indicates that nonsmokers are more sensitive to smoke, including cardiovascular effects, and that sidestream smoke contains higher concentrations of gas constituents, including carbon monoxide. Pathophysiological and biochemical data after short- and long-term environmental tobacco smoke exposure show changes in endothelial and platelet function as well as exercise capacity similar to those in active smoking. Therefore, passive smoking is a relevant risk factor for heart disease morbidity and mortality.

Animals↗
PubMed1995

Atherosclerotic lesions in humans--plaque stabilization and regression.

Although lowering of total- and LDL-cholesterol with different methods, like dietary restrictions mostly combined with lipid-lowering drugs (monotherapy or combined drug therapy) or changes in lifestyle (e.g., cessation from smoking) have demonstrated significant clinical benefits in a number of clinical trials, the magnitude of angiographically proven regression of atherosclerotic lesions is relatively small despite aggressive lipid-lowering regimens. A potentially important therapeutic target especially for limited indications includes the use of LDL-apheresis, where functional and later morphological regression occurs.

Arteriosclerosis↗
PubMed1995

[Thrombocyte function of healthy probands taking 50 mg of acetylsalicylic acid per day].

The antithrombotic effect of acetylsalicylic acid (ASS) is attributed in part to its inhibitory action on platelet cyclooxygenase and, thereby, thromboxane A2 (TXA2) formation. The therapeutic goal of low-dose ASS regimens was the development of a preparation showing a high inhibitory capacity on platelet TXA2 generation whilst leaving vascular prostaglandin I2 (PGI2) synthesis unaffected, thereby minimizing side effects. The effect of a new acid-resistant preparation of 50 mg ASS (Thrombo-ASS 50 mg) on plasma levels of ASS, salicylate, TXB2, 11-dehydro-thromboxane B2, serum thromboxane B2 and malonyl dialdehyde, the conversion of exogenous 14C-arachidonic acid to TXB2 and hydroxy-5,8,10-heptadecatrienoic acid (HHT), as well as on the urinary metabolites 2,3-dinor-6-oxo-PGF1 alpha and 2,3-dinor TXB2, were compared in a crossover trial to those of a marketed preparation (Aspirin 100 mg) in healthy volunteers after a single dose and repeated administration of ASS. While platelet activity was inhibited by both the test and the reference substance to a comparable extent, vascular PGI2 production (as determined by urinary 2,3-dinor-6-oxo-PGF1 alpha excretion) was less affected by the test substance. These findings confirm the claim that a dosage of 50 mg ASS administered daily as an enteric coated or uncoated tablet is sufficient to almost completely block platelet cyclooxygenase, while the respective vascular enzyme is only minimally affected.

Adult↗
PubMed1995

PGE0 inhibits collagen and glycosaminoglycan-synthesis in the rabbit arterial wall.

The influence of 13,14-dihydro-PGE1 (PGE0), a biologically active metabolite of PGE1, on collagen and glycosaminoglycan synthesis by the rabbit arterial wall was assessed and compared with the effect of PGE1. Collagen (COL) and glycosaminoglycan (GAG) synthesis was measured using 14C proline- and 35S-incorporation respectively and both were subsequently quantified by autoradiography. PGE1 decreased GAG-synthesis by 40%, while PGE0 caused a 25% decrease. COL-synthesis after PGE1 treatment was diminished by 35%, while the biologically active metabolite caused a drop of 30%. Five and 15 micrograms/kg doses of both compounds were almost equally effective, 1 microgram was without effect. These findings indicate that PGE0 shares the inhibitory effect of PGE1 on COL and GAG biosynthesis. This metabolite has about 60 to 70% of the biological activity of its parent compound PGE1. These results suggest that part of the effects of PGE1 in inhibiting extracellular matrix production could be due to its metabolite PGE0.

Alprostadil↗
PubMed1995

Radiation-induced vascular damage.

A 55-year-old male underwent detailed angiological and biochemical investigation because his daughter suffered from myocardial infarction in the 29th gestational week. An inborn familial plasma factor defect and increased Lp(a) were detected. Localized vascular changes were found in the right femoral artery while the resting vascular system was normal. Anamnestic data revealed a testicular cancer and therapeutic irradiation in that area (5000 rad) 12 years ago.

Biological Factors↗
PubMed1989

[Nyctometry and flicker discrimination in diabetic retinopathy].

98 diabetics and 34 healthy probands were recruited for ophthalmoscopic evaluation of the retina with a fundus camera, and for functional tests of the retina using a flicker frequency analyzer and a nyctometer. One year later, funduscopic evaluation of the ocular fundal state was carried out, and the results compared with the original baseline set of functional parameters. In the control group of healthy probands, a result only partially duplicated in the group of diabetics. An age-corrected comparison of the two groups revealed no difference between the diabetics and the healthy probands. Attempts were made to identify groups displaying significant differences in retinal performance as evaluated by the procedures mentioned above, but neither taking duration of diabetes as a criterion, nor selecting for differences in the course of diabetic retinopathy enabled the identification of such groups. A decrease in retinal performance was seen in very severe stages of diabetic retinopathy. These functional tests are not suitable in the early stages of diabetic retinopathy for defining that group of high-risk patients in which rapid progression of diabetic retinopathy is to be expected.

Adult↗
PubMed1985

Controlled drug delivery in the treatment of diabetes mellitus.

Diabetes not only requires correction of an insulin deficiency but it also demands adequate insulin delivery. A short historical review is given over the first 60 years of insulin treatment, where emphasis was mainly on the correction of insulin deficiency. Despite concerted efforts, metabolic results were often poor, and there was a high incidence of late complications, which will be described briefly. A major aim of new treatment approaches, which emphasizes better routes of insulin delivery, is the prevention or reversal of these late complications. Closed-loop systems are infusion systems located outside the body which deliver insulin according to glucose values that are measured continuously. The state of the art for such systems will be described with examples of clinical applications and results. These systems aid and stimulate research, but offer no long-term application for treatment. Open-loop systems are portable, both external and implantable, and lack an accurate glucose sensor so that the loop can be closed. A number of insulin delivery systems have been developed in this category ranging from highly complex, fully implantable units, programable from outside, to simple basal-rate infusion pumps. Various pumps are designed to be used with varying delivery routes, and the evaluation of different routes will be a vital topic in this article. Pros and cons of the intravenous, intraperitoneal, and subcutaneous routes will be discussed, with supporting research referenced. Clinical experience will be cited for both the complex and the simple infusion systems. Other topics to be covered include feasibility of long-term treatment, complications of this new treatment approach, guidelines for patient instruction and supervision, requirements for treatment of large patient groups with pumps in a modern diabetes center, requirements for the physician, the influence of improved metabolic control on late complications (prevention or regression), the possibility for a portable closed-loop system, and future outlook. The primary author is the founder of an international study group on diabetes treatment with implantable insulin delivery devices. The common goals of this study group will also be presented. Special emphasis will be placed on a differentiated approach to treatment of Type I and Type II diabetes with a family of devices. Clinical work and results from a large patient group will be included throughout.

Adolescent↗
PubMed1984

Treatment of type I diabetic with subcutaneous insulin resistance by a totally implantable insulin infusion device ("Infusaid").

A 22-yr-old diabetic female is described who developed insulin resistance due to subcutaneous (and intramuscular) "malabsorption" of insulin resulting in recurrent ketoacidosis and sepsis. Intravenous insulin sensitivity was maintained. Diverse attempts to prevent metabolic decompensation by "external" methods failed. The insulin resistance was treated successfully by a totally implantable insulin infusion device ("INFUSAID") with no episodes of ketoacidosis in the 6 months following implantation. With this constant rate insulin infusion pump, and no supplementation of insulin dose by other means, the plasma glucose control is excellent and serum lipid and glycosylated haemoglobin (HbA1) levels have returned to normal.

Adult↗
PubMed1983

[Interaction of sulfinpyrazone (Anturan) and glibenclamide (Euglucon) in type II diabetic patients].

In a randomised double blind study on 19 with glibenclamide well controlled diabetics of type II the possible interaction between sulfinpyrazone (Anturan) and glibenclamide was studied with the help of the artificial endocrine pancreas. The trial substance in a dose of 800 mg/die or placebo were used over a period of 70 days. During the trial period and at the end of it there were no significant differences in the sulfinpyrazone group as compared to the placebo group concerning the metabolic control of the diabetic condition. It is therefore justified to assume that there exists no interaction between sulfinpyrazone and glibenclamide in this regard. The dosage of sulfinpyrazone used in this trial was well tolerated by all patients and no side effects were observed.

Adult↗
PubMed1983

Implanted constant basal rate insulin infusion devices for Type 1 (insulin-dependent) diabetic patients.

A multi-phase study was undertaken to compare the metabolic effect on unstable Type 1 diabetic patients of optimized conventional treatment with that of external or implantable insulin delivery devices. External units were programmed to simulate implantable constant basal rate insulin infusion pumps with additional insulin doses given by subcutaneous injection or delivered by the pump. The study was continued using external devices with an optimal, meal-adjusted insulin profile simulating programmable, remote-controlled, implantable devices. Such good metabolic control was achieved using the constant insulin infusion, supplemented by two subcutaneous injections of insulin daily, that it justified the implantation of constant rate pumps in five Type 1 patients. Patients with the implanted devices achieved a near-normal life style, experienced significantly fewer hypoglycaemic reactions and had significantly improved glycosylated haemoglobin A1 and mean blood glucose values.

Adolescent↗