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H J Krzywanek

Publications and source records attributed to H J Krzywanek.

At least 19 recordsLinked to original sources
PubMed1999

Pharmacokinetics and pharmacodynamic effects of a new antibody glycoprotein IIb/IIIa inhibitor (YM337) in healthy subjects.

BACKGROUND: This study describes the first administration of YM337, the Fab fragment of a humanized monoclonal antibody against the fibrinogen GP IIb/IIIa receptor, in healthy male humans. METHODS AND RESULTS: Platelet aggregation (20 micromol/L ADP), platelet adhesion, fibrinogen binding, bleeding time, and YM337 concentrations in plasma were studied in substudy 1 after single boluses of 0.025, 0. 05, 0.1, 0.2, and 0.4 mg/kg YM337 and in substudy 2 after a bolus (0. 35 mg/kg) plus 6 hours of infusion at different dose levels of YM337 (0.5, 0.75, 1.0, 1.5 microg. kg(-1) x min(-1)), with abciximab as reference drug (n=5 or 6 subjects per group). After the 0.2-mg/kg and 0.4-mg/kg boluses, fibrinogen binding was reduced by >80% and bleeding time was prolonged to approximately 60 minutes. Bolus followed by infusion of 1.0 and 1.5 microg x kg(-1) x min(-1) YM337 maintained inhibition of platelet aggregation >80%. Aggregation and bleeding time returned to normal within 24 hours. A bolus of 0.25 mg/kg of abciximab followed by an infusion of 0.125 microg x kg(-1) x min(-1) showed effects similar to those observed with the 0.5- and 0. 75-microg x kg(-1) x min(-1) infusion of YM337. In 53 subjects exposed to YM337, 1 case of transient thrombocytopenia and 3 minor bleeding events occurred. No human anti-chimeric antibodies were detected 2 weeks and 2 months after administration. CONCLUSIONS: YM337 effectively inhibits IIb/IIIa-mediated platelet aggregation and adhesion in humans. The results of this phase 1 study will give rise to further clinical evaluation of YM337.

Abciximab↗
PubMed1999

Spontaneous platelet aggregation as a predictive risk factor for vascular occlusions in healthy volunteers? Results of the HAPARG Study. Haemostatic parameters as risk factors in healthy volunteers.

The HAPARG Study (haemostatic parameters as risk factors in healthy volunteers) was performed in a subset of volunteers taking part in the MARISK Study (Mainzer Risikoindikatoren Studie für die koronare Herzkrankheit) sponsored by the German Ministry of Research and started in 1984. A previous study (Yamanishi et al., Thromb Haemostas 1985;54:539-543) had shown that spontaneously enhanced platelet aggregation as measured with the PAT-III-test and higher fibrinogen concentrations are significant risk factors for new vascular occlusions in diabetic patients. It was the aim of the HAPARG Study to establish whether spontaneous platelet aggregation and other hemostatic variables are independent risk factors for vascular occlusions in healthy volunteers. Employees of a chemical/pharmaceutical company aged 40-65 years and personnel of the University of Mainz, aged 30-60 years were included in this prospective study. Besides anamnestic data such as on smoking, hypertension and diabetes, blood pressure, the ankle/arm Doppler-index and an ECG were recorded and serum cholesterol, HDL, LDL, triglycerides, uric acid and glucose were measured. Men (1884) and women (989) entered the study and were followed for 4-6 years. In the age group of 30-50 years, more women than men were included. During the observation period 53 vascular occlusions occurred (36 coronary and nine cerebral events and eight peripheral vascular occlusions). Only three of these endpoints occurred in women. Besides age (odds ratio = 1.7, P = 0.02) and gender as expected risk factors, the multivariate logistic stepwise regression analysis revealed smoking (odds ratio = 2.2, P = 0.008), lower HDL-levels (odds ratio = 2.2, P = 0.013), elevated diastolic blood pressure (odds ratio = 1.4. P = 0.004) followed by spontaneous platelet aggregation (odds ratio = 1.1, P = 0.037), and slightly elevated blood glucose (P = 0.0047) as significant risk factors for men. Higher fibrinogen levels missed significance in this analysis (P = 0.059). None of the other hemostatic parameters showed a significant correlation with the vascular events. To our knowledge, this has been the first prospective trial in a large population of healthy individuals in which a platelet function parameter has been studied together with other possible risk factors. Spontaneously enhanced platelet aggregation is probably an independent risk factor and, like elevated fibrinogen and other haemostatic variables, an indicator of an ongoing active atherosclerotic process.

Adult↗
PubMed1994

Acetylsalicylic acid--reocclusion--prophylaxis after angioplasty (ARPA-study). A randomized double-blind trial of two different dosages of ASA in patients with peripheral occlusive arterial disease.

We report on a randomized controlled clinical trial in patients with peripheral occlusive arterial disease who have been successfully treated with angioplasty. The efficacy and the rate of side effects of two doses of ASA (300 mg vs. 1000 mg daily) have been compared during a treatment period of 6 months after angioplasty. It was planned to include a total of 600 patients in the trial. A predefined interim analysis of 200 patients which was performed after the actual inclusion of 218 patients showed identical reocclusions rates and a very similar frequency of side effects in both treatment groups. The study was then terminated since it was not expected that further continuation would lead to a relevant difference between the two treatment groups concerning efficacy or side effects. Patients already included in the trial at the interim evaluation were included in the final analysis, leading to a total number of 223 patients. Finally 112 patients had been randomized to receive a daily dose of 300 mg ASA and 111 patients to receive 1000 mg ASA. Reocclusions occurred in 18 patients (16%) on 300 mg of ASA/day and in 20 patients (18%) receiving 1000 mg ASA/day. The study was interrupted because of side effects in 27 patients (24%) in the 300 mg/day group and in 27 patients (24%) in the 1000 mg/day group. Mostly subjective gastric complaints were the cause of interruption in 17 patients (15%) in the 300 mg group and in 21 patients (19%) receiving the higher dose regimen. So the reocclusion rate was identical in both dosage-groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1986

Haemostasiological parameters as risk factor for new arterial occlusions in diabetics.

PARD is a prospective study sponsored by the German Research Council with the aim to establish if spontaneously enhanced platelet aggregation or changes of other hemostatic variables are risk factors for new vascular occlusions in diabetic patients. 363 diabetics (aged 45-65, 232 men, 131 women) have been observed for at least 5 years. Of the 232 men, 53 were on diet, 104 on oral antidiabetic agents and 75 on insulin. Of 131 women 16 were on diet, 46 on oral antidiabetic drugs and 69 on insulin. At entry a medical history was obtained and clinical examinations and laboratory tests were performed. Hemostatic tests and clinical examinations were repeated at 3 month's intervals. The life status was followed for all patients with the exception of 2. Until December 31, 1984, 42 patients had died, 23 from cardiovascular disease and 19 from other causes. 13 patients suffered a myocardial infarction, 11 a stroke and 53 a peripheral arterial occlusion. The occurrence of new vascular occlusions was significantly higher in men with enhanced spontaneous platelet aggregation measured by PAT III. This was not the case for women. Other hemostatic parameters with some relation to cardiovascular complications, again only in men, were fibrinogen, von Willebrand factor together with some established risk factors as triglycerides and hypertension.

Aged↗
PubMed1985

PARD: platelet aggregation as a risk factor in diabetics: results of a prospective study.

PARD is a prospective study sponsored by the German research council with the aim to establish whether spontaneously enhanced platelet aggregation or changes of other hemostatic parameters are risk factors for new vascular occlusion in diabetic patients. Hemostatic parameters have been measured in diabetic patients at 3 month-intervals (363 patients aged 45-65 at recruitment). Of the 232 men, 53 were on diet, 104 on oral antidiabetic drugs and 75 on insulin. Of 131 women 16 were on diet, 46 on oral antidiabetic drugs and 69 on insulin. Baseline data and preliminary results obtained between May 1977 and December 31, 1983 are presented. 22 patients have died. 17 diet from cardiovascular disease, 3 from pancreatic cancer and 2 from other causes. 51 patients suffered a myocardial infarction, stroke or peripheral arterial occlusions. The mean levels of spontaneous aggregation (angle alpha-PAT III), F VIIIC, F VIII R:AG, fibrinogen, antithrombin III and plasminogen were higher in men who died or suffered cardiovascular occlusions than in those without these events. In women this difference is less pronounced or absent. In women the mean values of several hemostatic parameters at baseline were higher than in men and the incidence of cardiovascular occlusions was lower. The interim results lead to the hypothesis that spontaneous aggregation, high levels of F VIIIC, F VIII R:AG and to some extent also high levels of fibrinogen, antithrombin III and plasminogen may be indicators of progressive vascular disease and could be useful as predictors of vascular occlusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1977

Photometric platelet aggregation test III: a new tool for the detection of enhancet platelet aggregation.

In clinical investigation on ehnanced platelet aggregation the changes of the various tests with time after blood sampling must be considered. The photometric PAT III for the evaluation of spontaneous aggregation showed enhanced aggregation in a high percentage of patients with vascular disease, and prospective data obtained so far make it likely that enhanced aggregation is a risk factor for thrombosis. More prospective studies are necessary to prove whether continuously enhanced spontaneous platelet aggregation is indicating progressive atherosclerosis.

Coronary Disease↗
PubMed1976

On the measurement of spontaneous platelet aggregation. The platelet aggregation test III. Methods and first clinical results.

A new measuring device was developed for the study of "spontaneous" aggregating activity of thrombocytes. In the photometric platelet aggregation test (PAT III) 0.6 ml of platelet-rich plasma (PRP) are rotated in a disc-shaped cuvette at 20 rpm and 37 degrees C. Changes in optical density of PRP which are induced by the formation of platelet aggregates are continuously registered using a chart recorder. PAT III was developed for the detection of enhanced platelet aggregation, indicating a risk of thrombosis and thromboembolic complications. In 146 healthy individuals a certain percentage showed slight primary aggregation (alpha1) which in some cases was followed by marked aggregation (alpha2) at a certain time (Tr) after the beginning of rotation. The percentage of individuals showing alpha2 increased with age. An increase of plasma pH in the rotating sample, which was caused by diffusion of CO2, was an important conditioning factor for aggregation. The test results depended on the platelet count in PRP. Aggregation curves were suppressed by admixture of erythrocytes and lipid turbidity. The tendency of platelets to aggregate increased within 60-90 min following blood sampling. During this period the interval to the onset of aggregation (Tr) became shorter and the maximum aggregation speed (alpha 2) increased with time. PAT III yielded reproducible results when it was carried out more than 60 min after blood drawing. In a group of 327 diabetic patients "spontaneous" aggregation occurred more frequently in all age groups as compared with the controls. Additional equipment was available for the registration of ADP-, collagen-, or epinephrine-induced aggregation similar to Born's and O'Brien's method. The device can easily be mounted on an Eppendorf photometer without further alterations.

Age Factors↗
PubMed1975

[Measurement of spontaneous platelet aggregation. Platelet aggregation test III (author's transl)].

A new measuring device for the estimation of the "spontaneous" aggregating activity of thrombocytes has been developed. In this photometric platelet aggregation test (PAT III) a small amount (0.6 ml) of platelet-rich plasma (PRP) is being rotated in a disc-shaped cuvette at 20 rpm, at 37% C. Changes in optical density of PRP which are induced by the formation of platelet aggregates are continuously registered using a chart recorder. The decisive trigger mechanism for aggregation is an increase of plasma pH in the rotating sample which is caused by evaporation of CO2. The results of the test depend on the platelet count in PRP. Aggregation curves are misrepresented by admixture of erythrocytes and lipid turbidity. The tendency of platelets to aggregate increases within 60-90 min following blood sampling. During this period the time interval to the onset of aggregation(Tr) is shortening, and the maximum aggregation speed (alpha2) is increasing. The spontaneously enhanced aggregation tendency of thrombocytes may be reliably measured from 60 min after drawing the blood. The reason for these time-dependent changes which are also demonstrable in ADP-collagen-or epinephrine-induced aggregation is probably the primary shape change of platelets, which occurs after blood drawing and makes them "stickly" and aggregable. PAT III was developed for the detection of enhanced platelet aggregation, indicating a risk of thrombosis and thromboembolic omplications. The new measuring device has been designed as "universal" aggregometer. Additional equipment is available for the registration of ADP-collagen-or epinephrine-induced aggregation similar to Born's and O'Brien's methods. The device may be mounted easily on an Eppendorf photometer without further modifications.

Adenosine Diphosphate↗