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D Wichterle

Publications and source records attributed to D Wichterle.

14 recordsLinked to original sources
PubMed2005

Second derivative of the finger arterial pressure waveform: an insight into dynamics of the peripheral arterial pressure pulse.

The study investigated second derivative of the finger arterial pressure waveform (SDFAP) in 120 healthy middle-aged subjects and in 24 subjects with essential hypertension. SDFAP consists of 5 sequential waves 'a'-'e'. Their normalized magnitudes (B/A, C/A, D/A, and E/A) were calculated. In multivariate regression analysis, B/A and C/A correlated only with age. D/A independently correlated with age, heart period, mean blood pressure (MBP), body height, and gender. E/A independently correlated with age and MBP. D/A and E/A were higher (0.42+/-0.16 vs. 0.33+/-0.14, p = 0.05 and 0.63+/-0.15 vs. 0.45+/-0.14, p < 0.001), while B/A and C/A were lower (1.04+/-0.16 vs. 1.20+/-0.17, p = 0.002 and 0.09+/-0.15 vs. 0.26+/-0.20, p = 0.001) in hypertensives compared to sex- and age-matched controls. After the adjustment for MBP, heart period, and body mass index (ANCOVA), independent discriminative power was preserved only for indices B/A and C/A (p = 0.001 and 0.021, respectively). Therefore, B/A and C/A provide additional information about simple clinical characteristics and might reflect the structural alteration of the arterial wall in hypertensive subjects.

Adult↗
PubMed2002

[Heart rate turbulence--a new ECG predictor for risk of sudden death].

Heart Rate Turbulence (HRT) is a newly described physiological chronotropic response of sinus rhythm following a single ventricular premature beat (VPB) consisting of early acceleration and later deceleration of heart rate. Using two large independent cohorts of postinfarction patients, the absence of HRT was retrospectively validated to be a potent multivariate risk predictor, stronger than a number of currently available risk stratifiers. Although exact pathophysiological mechanism of HRT remains speculative, it is now believed that HRT arises from the haemodynamic changes and baroreceptor reflexes that occur following a VPB. Therefore, HRT descriptors (Turbulence Onset and Turbulence Slope) may serve as very reasonable, Holter--based surrogates of baroreflex sensitivity available in clinical practice. The aim of this review is to summarise the current knowledge on pathophysiological mechanisms of HRT and to discuss practical problem of its detection.

Death, Sudden, Cardiac↗
PubMed2001

Both fenofibrate and atorvastatin improve vascular reactivity in combined hyperlipidaemia (fenofibrate versus atorvastatin trial--FAT).

OBJECTIVE: It has been repeatedly proven that statins improve endothelial function in isolated hypercholesterolaemia but there is far less evidence in the case of combined hyperlipidaemia. Studies assessing the effects of fibrates on endothelium have been neglected. Therefore, we conducted a trial in which the effects of fenofibrate and atorvastatin monotherapy on both endothelium-dependent vascular reactivity and biochemical parameters were compared in patients with combined hyperlipidaemia. METHODS: 29 otherwise healthy males (aged 47.4+/-7.8 years) with combined hyperlipidaemia (total cholesterol 7.55+/-1.20 mmol/l, triglycerides 5.41+/-4.54 mmol/l) were included into the randomised, single-blind, cross-over study to receive either 200 mg of micronised fenofibrate or 10 mg of atorvastatin daily--each of the drugs for a period of 10 weeks. Analysed biochemical parameters were as follows: serum total-, LDL- and HDL-cholesterol, apolipoproteins A-I and B, triglycerides, fibrinogen, uric acid, C-reactive protein (CRP), insulin, and homocysteine. Endothelial function was investigated by duplex Doppler ultrasonography at the brachial artery. Two indices of endothelial-dependent postischaemic changes were used - the recently introduced index of peak blood flow (PBF) representing the level of reactive hyperaemia and traditional flow-mediated dilatation (FMD). RESULTS: We observed a small improvement in FMD after both fenofibrate and atorvastatin (from 2.26% to 2.98% and 2.87%, respectively; NS). PBF increased from 448 ml/min to 536 ml/min after fenofibrate (P=0.04) and to 570 ml/min after atorvastatin (P=0.03). The effects of both fenofibrate and atorvastatin on endothelial function did not differ significantly (P-values of 0.82 and 0.47 for FMD and PBF, respectively). Significant correlations (P<0.01) between the changes of vascular reactivity and biochemical indices were found between FMD and CRP (r=-0.60) and between both FMD and PBF, and insulinaemia (r=-0.48 and -0.56, respectively) only during treatment with fenofibrate. CONCLUSIONS: Both fenofibrate and atorvastatin significantly improved endothelium-dependent vascular reactivity without mutual difference. The PBF was superior to FMD for the detection of this improvement. The beneficial effect of both drugs did not correlate with the change of lipid profile during therapy. The improvement of vascular reactivity during treatment with fenofibrate (opposed to atorvastatin) was related to the reduction of indirect marker of chronic vessel wall inflammation and of insulin resistance. The PBF was more reproducible than FMD because of considerably lower intra-subject variability.

Adult↗
PubMed2000

[Function and dysfunction of the endothelium].

Endothelium is a multi-functional barrier separating blood from interstitium. It plays a role in coagulation, inflammation, angiogenesis and it has vasomotor functions. The endothelial dysfunction can be considered as an initial stage of atherosclerosis. Using morphological and biochemical methods it is possible to study the influence of cardiovascular risk factors on the vessels and the effect of therapeutic interventions. A short review of endothelial functions, endothelial dysfunction and its quantification methods is presented in this article.

Blood Coagulation↗
PubMed2000

Stability of the noninvasive baroreflex sensitivity assessment using cross-spectral analysis of heart rate and arterial blood pressure variabilities.

BACKGROUND: Depressed baroreflex sensitivity (BRS), usually estimated using the invasive phenylephrine method or the nitroprusside test, is significantly and independently associated with an increased risk of malignant ventricular arrhythmias and sudden cardiac death in patients surviving acute myocardial infarction. Several investigators have compared the standard phenylephrine test and different noninvasive methods. HYPOTHESIS: This study evaluated the influence of different body positions with different breathing regimes on cross-spectral baroreflex indices (coherence between the spectral densities of blood pressure and cardiac cycle variabilities) in both low- and high-frequency bands. METHODS: The data were obtained in 103 patients (73 males, aged 53 +/- 12 years) with coronary artery disease and/or hypertension. Simultaneous electrocardiographic and noninvasive blood pressure recordings were obtained in each subject in both supine and sitting positions during both spontaneous and slow and fast controlled respiration (0.1 and 0.33 Hz). RESULTS: The results show a significant bias and disagreement between noninvasive baroreflex sensitivity (BRS) indices. The mean values of the baroreflex in low frequency ranged from 5.0 +/- 5.3 to 10.1 +/- 7.9 ms/mmHg, while in high frequency, the mean values ranged from 6.6 +/- 6.1 to 10.1 +/- 7.9 ms/mmHg. The limits of agreement ranged from +/-1.7 to +/-4.1 ms/mmHg with bias from -1.0 to +0.7 ms/mmHg. CONCLUSION: A comprehensive comparison of different methods shows that BRS estimated in low-frequency band in sitting position during spontaneous respiration is the most representative part of the global baroreflex gain.

Adult↗
PubMed2000

Cross-spectral analysis of heart rate and blood pressure modulations.

The cross-spectral analysis of heart rate (HR) and blood pressure (BP) variabilities provides "amplitude" and "phase" related measures. Compared to the amplitude measure, that is the baroreflex gain, the phase related measure characterizing the time lag between HR and BP oscillations has been studied to a much lesser extent. A population of 103 patients (73 men, 30 women, aged 53 +/- 12, range 20-82 years) referred for the management of coronary artery disease and/or hypertension were studied. In each subject, electrocardiogram and BP recordings were obtained in the supine and sitting positions of 5 minutes of rest (spontaneous respiration), 3 minutes of controlled respiration at 0.1 Hz (slow-controlled respiration), and 3 minutes of controlled respiration at 0.33 Hz (fast-controlled respiration). The frequency of maximum coherence (above the arbitrary threshold of 0.5) of BP and RR interval variabilities was searched between 0.033-0.133 Hz and 0.200-0.400 Hz to obtain baroreflex gain and phase shift in low and high frequency bands, respectively. Mean phase shifts of -79.1 and -67.0 degrees (-2.4 and -2.1 s) were found during slow-controlled respiration in the supine and sitting body positions, respectively. The mean phase shift between systolic BP and RR interval in the low frequency band was found between 83 and -109 degrees for body positions and respiration regimes. The actual baroreflex related time lag between systolic BP and RR variations was found between 3.5 and 5.1 seconds. The study concludes that the appropriate, and not always easy, selection of the frequency of maximum coherence between BP and HR oscillation is crucial for an accurate cross-spectral assessment of baroreflex sensitivity.

Adult↗
PubMed2000

[Familial hyperlipoproteinemias--correlations between phenotypes and genotypes].

Within the grant project patients with familial hyperlipoproteinaemias have been examined. The examination was performed in the oldest lipid clinic and research laboratory in the world. The classification of lipid metabolism disorders was based upon a detailed biochemical analysis of plasma lipids including electrophoresis and assessment of apolipoprotein levels. Then optimal treatment regimen could be established. The project was aimed to evaluate the efficacy of different treatment regimens in different types of hyperlipoproteinaemias. Biochemical parameters and mainly the impact of treatment of hyperlipoproteinaemia on morphology and function of the vessel wall was monitored. The non-invasive ultrasound measurement of the intima thickness of carotid arteries was used. For more precise diagnosis of genetically determined disorders of lipid metabolism a large scale of methods of molecular biology was introduced. These methods enable confirmation of familial hypercholesterolaemia, familial defective apolipoprotein B-100 or studying polymorphism of apolipoprotein E. The effort of the authors of the project was to maximally utilise the results of basic and applied research in formulating recommendations for everyday practice of physicians.

Humans↗
PubMed1995

[Anti-insulin antibodies and insulin resistance].

The submitted review deals with the phenomenon of immunological insulin resistance in insulin dependent diabetics which develops as a result of the presence of circulating anti-insulin antibodies as a response of the organism to administered insulin. This phenomenon is a liminal situation when anti-insulin antibodies exceed as to their concentration and affinity a certain arbitrary limit and the increasingly impaired pharmacokinetics of insulin cause a clinically manifest metabolic decompensation of the disease with the necessity of large daily doses of exogenous insulin. The authors discuss factors ensuing from the type of the administered insulin preparation, as well as the biological predisposition of the patient which potentiates the production of anti-insulin antibodies. Some laboratory methods are discussed which are used for the assessment of anti-insulin antibodies in vitro and the authors summarize individual physical variables which characterize the antibody system and which can be extracted by special mathematical procedures from experimental radioimmunoanalytical data. Only a detailed characterization of the antibody system makes it possible to evaluate the influence of this system on the pharmacokinetics of insulin.

Diabetes Mellitus, Type 1↗
PubMed1994

[The effect of Proglicem in patients with an organic hyperinsulinism syndrome].

BACKGROUND: Organic hyperinsulinism is treated as a rule conservatively with diazoxide (Proglicem) which has a hyperglycaemic effect. In some patients, however, treatment fails and severe hypoglycaemia persists. The objective of the present investigation was to find simple criteria for evaluation of the aptness (effectiveness) of this treatment. METHODS AND RESULTS: In 11 patients with a confirmed insulinoma Proglicem was administered for five days (3 mg/kg body weight) and serum insulin and the blood sugar level as well as their ratio (IRI:G) were followed-up. In eight patients the IRI/G coefficient declined from 10.5 +/- 7.7 to 5.8 +/- 2.9 (p < 0.001); only in three patients the coefficient increased from 4.6 +/- 2.9 to 14.9 +/- 12.3 (p < 0.001). Coefficient "k" from the modified Bergman model for the intravenous glucose tolerance test had identical results; there was statistically significant agreement between the two examinations. CONCLUSIONS: To assess the effectiveness of diazoxide treatment (Proglicem) on hypoglycaemia in nesidiomas it is sufficient to evaluate the IRI/G coefficient (on fasting) before and during diazoxide treatment (Proglicem, Schering Corp.).

Adult↗
PubMed1993

Insulin resistance and compensatory insulin secretion in middle-aged persons with hypertriglyceridemia.

Insulin secretion and insulin sensitivity were measured in hypertriglyceridemic patients using the frequently sampled intravenous glucose tolerance test. Three groups of men who were matched for age and body mass index were studied: eight healthy control subjects (C), seven patients with mild hypertriglyceridemia and normal glucose tolerance (TG), and seven with well-controlled type 2 diabetes with hypertriglyceridemia (TG-DM). The first-phase insulin response was increased by 116% in the TG group and decreased by 59% in the TG-DM group. The second phase of insulin secretion was increased in both TG groups (TG by 310% and TG-DM by 250%). The mean insulin sensitivity index (SI) was reduced by 50% in the TG group and by 60% in the TG-DM group. Glucose effectiveness (SG) was reduced by 30% in the TG-DM group compared with the control subjects.

Adult↗
PubMed1993

[Insulin secretion and sensitivity in middle-aged men in the initial stages of type II diabetes mellitus (evaluated by the "minimal model" method].

The objective of the work was to test the minimal model method based on computer evaluation of parameters (blood sugar level, insulin blood level) obtained during the intravenous glucose tolerance test with frequent collection of samples, when examining the insulin glucose homeostasis in patients in the initial stage of type II diabetes. The authors examined a control group of 8 healthy men, mean age 43.6 years, BMI 24.7 and a group of 7 men with type II diabetes, mean age 46.7 years, BMI 31.37. Indexes (phi 1 and phi 2--the first and second stage of insulin secretion, SG-glucose efficiency, SI-insulin sensitivity) were obtained by evaluation of the results, using a programme for a personal computer PC AT. In men of the control group the authors recorded the following values: phi 1 5.80 +/- 1.26 microU/ml x min/mg/dl, phi 2 6.43 +/- 5.15 microU/ml x min-2/mg/dl, SG 0.016 +/- 0.010 min-2. Diabetic patients were divided with a regard to the first stage of insulin secretion into two groups: the first one (n = 4) comprises those where the first stage is minimal (phi 1 = 0.80 +/- 0.68 microU/ml x min/mg/dl, phi 2 = 33.41 +/- 19.06 microU/ml x min-2/mg/dl, in the second group are those (n = 3) where the first stage of insulin secretion is maintained phi (1 12.23 +/- 5.51 microU/ml x min-2/mg/dl, phi 2 7.77 +/- 4.98 microU/ml x min-2/mg/dl). The second stage of insulin secretion in subjects of the first group is, as compared with controls, significantly higher (p < 0.05).

Adult↗
PubMed1993

[Modelling the kinetics of C-peptide and hepatic extraction of insulin (in type 2 diabetics and non-diabetics with hypertriacylglycerolemia)].

Increased glucose release from the liver which is responsible to a considerable extent for fasting hyperglycaemia in type 2 diabetics is associated with hepatic insulin resistance. Assessment of insulin extraction in the liver can therefore be useful in investigations of all pathophysiological conditions with deviations of glucose tolerance, or in the course of insulin secretion. The control group was formed by 8 healthy men, mean age 43.6 +/- 5.9 years, mean BMI 24.7 +/- 2.8. The authors examined also a group of 7 men with diabetes mellitus type II, mean age 46.7 +/- 5.9 years, BMI 31.4 +/- 8.9 and 6 men with hypertriacylglycerolaemia, mean age 44.2 +/- 3.1 years and mean BMI 26.2 +/- 1.4. All were examined by the intravenous glucose tolerance test with frequent blood sampling. In every sample the blood sugar level, insulin level and C-peptide level were assessed. The data were evaluated and the "hepatic insulin extraction index" was thus obtained. The "hepatic insulin extraction index" was significantly lower in type 2 diabetics throughout the experimental period (0-180 min.) as well as during individual intervals evaluated (0-20 min. and 20-180 min.). In subjects with hypertriacylglycerolaemia this index was lower only during the 0-20 min. interval. Changes of the "hepatic insulin extraction index" in patients with hypertriacylglycerolaemia do not reach the intensity recorded in diabetics and may thus indicate a milder grade of hepatic insulin resistance.

Adult↗