PubMed Health⌕ Search

Biomedical subjects

Jaroslav Racek

Publications and source records attributed to Jaroslav Racek.

17 recordsLinked to original sources
PubMed2006

The effect of intravenous iron on oxidative stress in hemodialysis patients at various levels of vitamin C.

BACKGROUND/AIMS: Vitamin C levels decrease during hemodialysis (HD), which deteriorates antioxidant defense. Vitamin C may also act pro-oxidatively, via reduction in Fe(III). We sought to determine whether intravenous iron (Fe(iv))-induced oxidative stress differs in HD patients with low and physiological vitamin C levels and whether intravenous vitamin C (C(iv)) administration during HD would change the response to Fe(iv). PATIENTS AND METHODS: Twenty patients with vitamin C deficiency (median 15.7 micromol/l, range 8.0-22.7) received Fe(iv) (100 mg iron sucrose between 150 and 180 min of HD). After 4 weeks of oral supplementation, the levels of vitamin C were comparable with those of controls (60.1 micromol/l, range 47.4-70.9). Patients were subsequently treated with (1) Fe(iv), (2) Fe(iv) and continuous 2 mg/min C(iv) throughout HD, (3) saline (S), and (4) S+C(iv). Plasma thiobarbituric acid reacting substances (TBARS) and vitamin C were assessed before, during and after FE(iv)(S), and 15, 30 and 60 min after infusion. RESULTS: Fe(iv) induced a comparable rise in TBARS in patients with vitamin C deficiency (before Fe(iv), 1.9 micromol/l, range 1.4-1.9; after Fe(iv), 2.6 micromol/l, range 2.3-2.9; p < 0.01) and in those with normal vitamin C (before Fe(iv), 1.9 micromol/l, range 1.7-2.1; after Fe(iv), 2.6 micromol/l, range 2.5-2.9; p < 0.01). Fe(iv)+C(iv) resulted in a greater increase in TBARS (after Fe(iv), 3.1 micromol/l, range 2.8-3.2) compared with Fe(iv) (p < 0.01). CONCLUSION: Iron sucrose-induced oxidative stress is comparable in HD patients with vitamin C deficiency and in those with normal vitamin C. We documented a pro-oxidative effect of vitamin C during Fe(iv)+C(iv) administration.

Administration, Oral↗
PubMed2006

Brain natriuretic peptide and N-terminal proBNP in chronic haemodialysis patients.

BACKGROUND: Brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are released into circulation as a result of congestive heart failure (HF). As HF and water overload are frequent complications in haemodialysis (HD) patients, we decided to study the levels of BNP and NT-proBNP and their changes during HD. METHODS: BNP and NT-proBNP levels were determined in 94 HD patients before and after a regular 4-h HD. We followed changes in these peptides during HD depending on age, sex, HF (NYHA classification and left ventricular ejection fraction [LVEF]), duration on HD, presence of hypertension, coronary artery disease, type of membrane used for HD [low-flux (LFx) or high-flux (HFx)] and body mass change during HD. Furthermore, patients basic medication and creatinine levels and presence of diabetes mellitus were monitored. RESULTS: Respectively,94% and 100% of the patients had pre-dialysis concentrations of BNP and NT-proBNP above the cut-off values for HF. The marker levels correlated significantly both before and after HD (r = 0.903 and 0.888, respectively, p < 0.001). BNP levels significantly decreased (p < 0.0001), whereas NT-proBNP significantly increased (p < 0.0001) during HD on LFx membranes. HD on HFx membranes caused greater decrease of BNP (compared to LFx membranes, p < 0.001), but also a decrease of NT-proBNP (p < 0.001).We did not find any significant differences in marker levels for HF and non-HF patients (NYHA classification). However, both peptides reached higher levels in the group with LVEF < or = 50% (p < 0.001 for both peptides). Body mass change during HD negatively correlated only with the change of NT-proBNP (r = -0.27, p < 0.05). In the multiple regression model, the change of both peptides during HD was significantly influenced by membrane type (p = 0.003 for BNP and p = 0.001 for NT-proBNP). NT-proBNP change during HD was further significantly influenced by LVEF (p = 0.012), sex (p = 0.002) and duration on HD (p = 0.006). CONCLUSIONS: Both BNP and NT-proBNP levels were significantly increased in HD patients prior to dialysis. The change in concentrations of both peptides during HD is influenced by membrane type. HD probably triggers increased production of both peptides and this increase is emphasized by impaired LVEF. This fact can be clinically observed only on NT-proBNP levels, because BNP levels are biased by significant removal of this protein during HD.

Aged↗
PubMed2006

Influence of chromium-enriched yeast on blood glucose and insulin variables, blood lipids, and markers of oxidative stress in subjects with type 2 diabetes mellitus.

The aim of this study was to determine the effect of chromium (Cr)- enriched yeast on blood glucose and insulin variables, blood lipids, and blood markers of oxidative stress in persons with type 2 diabetes mellitus (median duration: 3.0 yr). Thirty-six subjects (9 men, 27 women; mean age: 61.3 yr; mean body mass index: 34.33 kg/m2) were supplemented with 400 microg Cr/d as Cr-enriched yeast (n = 19) or placebo (n = 17) for 12 wk in a randomized, double-blind study. The most interesting results were obtained by comparison of the change in the placebo group to the change in the Cr group. The Cr group showed a significantly greater increase in serum Cr compared to the placebo group (p < 0.05). Supplementation with Cr-enriched yeast was associated with a significant decrease in fasting serum glucose compared to placebo (p < 0.01). Blood markers of oxidative stress glutathione peroxidase activity and levels of reduced glutathione were essentially unchanged in the Cr group after 12 wk, but decreased significantly in the placebo group (p < 0.05, p < 0.01, respectively). Serum HbA1c and glycated protein (fructosamine) were essentially unchanged in the Cr group, whereas HbA1c tended to increase in the placebo group (from 6.94% to 7.11%). Fasting serum insulin decreased in both groups, with a greater tendency in the Cr group (-16.5% vs -9.5%). These data suggest that supplementation of well-controlled type 2 diabetics with Cr-enriched yeast is safe and can result in improvements in blood glucose variables and oxidative stress.

Aged↗
PubMed2006

Measurement of carnitine in hemodialysis patients - adaptation of an enzymatic photometric method for an automatic analyzer.

BACKGROUND: The main goal of this work was to describe the analytical characteristics of an enzymatic photometric test for carnitine determination and its automation using an Olympus analyzer. METHODS: We used a test from Roche intended for manual processing and tried to apply it for use on an Olympus AU 400 analyzer. The analytical parameters of our modified technique were determined using external quality controls and kit controls, and by measurements in venous blood samples from 85 chronically hemodialyzed patients (before and after hemodialysis) and from 68 healthy blood donors serving as controls. RESULTS: A reference value for free carnitine was estimated parametrically as 40.1+/-17.8 micromol/L. The mean bias for eight control measurements was 5.1%. Sensitivity was calculated as the limit of quantification at 2.6 micromol/L. The intra-assay coefficient of variation was 2.4%. The inter-assay coefficient of variation was 8.3%. Analytical recovery was 101.8%, 99.5% and 95.4%. CONCLUSIONS: The main advantages of our automated method in comparison to the original manual method are the smaller amounts of samples, reagents and diluents required and the shorter analysis time. As hemodialysis patients often suffer from carnitine deficiency, we conclude that its determination may be helpful for diagnostic verification.

Adult↗
PubMed2006

Ischemic training and immunosuppressive agents reduce the intensity of ischemic reperfusion injury after kidney transplantation.

OBJECTIVES: Ischemia-reperfusion injury affects posttransplant renal function, directly increases the probability of acute rejection, and is associated with chronic rejection and impaired long-term function. Animal studies suggest that ischemic preconditioning enhances resistance to ischemia and may be augmented by treating donors using immunosuppressant agents. This study sought to confirm the hypothesis that a combination of ischemic training and immunosuppression prior to renal harvest would maximize a transplanted kidney's resistance to ischemia-reperfusion injury. MATERIALS AND METHODS: Landrace pigs underwent either preharvest immunosuppression plus left kidney ischemic training (group 1, n=6) or ischemic training alone (group 2, n=6). Immunosuppression was composed of mycophenolate mofetil (20 mg/kg) and tacrolimus (0.1 mg/kg) administered intravenously 30 minutes before training. Training comprised 2 cycles of left renal pedicle occlusion for 5 minutes followed by release (reperfusion) for 10 minutes. Warm renal ischemia was then induced by clamping the left renal pedicle for 30 minutes, followed by heterotopic left kidney transplantation. Blood from the transplanted kidney renal vein was sampled directly at 0, 10, 20, 40, and 60 minutes posttransplantation for malondialdehyde (a reactive oxygen species marker), tumor necrosis factor-alpha (TNF-alpha), interleukins 6 and 8 (inflammatory cytokines), and erythrocyte-reduced glutathione (an antioxidant). Renal histology was graded on a 3-point scale. RESULTS: Reperfusion levels of malondialdehyde, TNF-alpha, and interleukin 6 were significantly lower in group 1 at both 40 and 60 minutes. None of the animals in group 1 (0/6) that received preharvest immunosuppression showed severe interstitial inflammation, compared with 4 of 6 animals in group 2 that did (P<.03). CONCLUSIONS: Preharvest immunosuppression with mycophenolate mofetil and tacrolimus significantly decreases immediate posttransplant reactive oxygen species and inflammatory cytokine production, enhances the protective effect of ischemic training, and should not only reduce ischemiareperfusion injury in transplanted kidneys but also should enhance immediate and long-term graft function while preventing acute rejection.

Animals↗
PubMed2005

Average arch widths and associated changes between initial, post-treatment and post-retention measurements.

Computer image monitoring was used for evaluation of dental arch changes. A new special device captured geometrically calibrated images permitting comparison of several different dental casts. In the first part of this study 792 sets of study casts were screened. Measurements of dental arch width between reference points of canines, first premolars and first molars were made: upper jaw: men: canines: 35.1 +/- 0.13 mm; first premolars: 37.5 +/- 0.13 mm; first molars: 48.1 +/- 0.19 mm; women: canines: 33.4 +/- 0.13 mm; first premolars: 35.6 +/- 0.15 mm; first molars: 46.7 +/- 0.19 mm. In the second part of the study, changes between initial, post-treatment and post-retention alignment (5-years after orthodontic therapy) of upper and lower dental arch of 36 subjects were analyzed. Upper and lower arch compression in first premolars and molars area was visible before treatment. We conclude that computer image monitoring can be used for evaluation of dental arch changes during the different steps of treatment.

Bicuspid↗
PubMed2005

Asymmetric dimethylarginine, homocysteine and renal function--is there a relation?

The adverse effect of hyperhomocysteinemia on the vascular wall can be partially explained by increasing plasma concentration of asymmetric dimethylarginine (ADMA), a potent inhibitor of nitric oxide synthase. The aim of the study was to compare ADMA and homocysteine levels in three groups of subjects: blood donors with normal homocysteine concentration (group A), patients with hyperhomocysteinemia and normal kidney function (group B) and hemodialysis patients who are known to be hyperhomocysteinemic (group C). Concentrations of homocysteine (enzymatic method), ADMA (enzyme-linked immunoassay) and creatinine (Jaffe method) in EDTA plasma were measured. Plasma ADMA levels were significantly higher in both groups with hyperhomocysteinemia (1.60+/-0.56 micromol/L in group B, 1.81+/-0.57 micromol/L in group C) when compared with those in blood donors (0.82+/-0.29 micromol/L, p<0.001 in both cases). Significant positive correlations were found between concentrations of ADMA and homocysteine (r=0.42, p<0.0001), ADMA and creatinine (r=0.39 p<0.001), homocysteine and creatinine (r=0.69, p<0.0001), age and homocysteine (r=0.47, p<0.001), age and ADMA (r=0.57, p<0.001) and age and creatinine (r=0.37, p<0.001). Increased ADMA concentrations in hyperhomocysteinemic patients were confirmed, but multiple linear regression analysis showed that this significant correlation is only apparent due the dependence of both parameters on age.

Adult↗
PubMed2004

Aspects of oxidative stress in children with type 1 diabetes mellitus.

Diabetes mellitus is considered to be one of a rank of free radical diseases. The existence of hyperglycemia produces increased oxidative stress (OS) via non-enzymatic glycation, glucose autoxidation, and alterations in polyol pathway activity with subsequent influences on the whole organism. In childhood, Type 1 diabetes prevails and is characterized by its autoimmune character with progressive destruction of beta cells and lack of insulin in genetically predisposed patients. Our study focused on diabetic children and their 1st degree relatives and confirmed increased oxidative stress in diabetic children as well as a similar tendency in their siblings. Following this, we carried out a one-year study comprising diabetic children supplemented with vitamins E and C. The vitamin treatment improved diabetes control and reduced markers of oxidative stress substantially when compared with non-supplemented diabetic children. As oxidative stress impairs not only lipids and proteins, but also DNA, we attempted to examine the level of DNA strand breaks as well as DNA repair processes using comet assay modifications. Though children with Type 1 diabetes demonstrated increased oxidative stress (lower SOD and GSH when compared with healthy children), their oxidative DNA damage (measured as DNA strand breaks) were not substantially altered compared with normals. On the other hand, their DNA repair capacity was significantly increased. This demonstrates a stimulated DNA repair process that is most certainly a response to the permanently elevated state of oxidative stress. Owing to the presented results, it is appropriate to ponder the increased influence of oxidative stress on children with Type 1 diabetes and to take into account this fact when considering their treatment.

Adolescent↗
PubMed2003

An evaluation of the influence of therapeutic interventions on serum trace element levels in groups of patients.

The aim of the study was to propose a method of large amount data evaluation. A new graphical method for data evaluation was suggested: the data were ranked according to the initial values and both the initial values and final values were intersected by polynomial curves. This method was used in the following situations: 1. Serum levels of Mg and Zn were measured just before and after hemodialysis (HD) in 87 patients in chronic renal failure. 2. Mg levels in serum, red blood cells and urine were estimated in 20 patients before and after administration of a Mg containing drug. Three basic graphic forms of curves were established: 1. Significant decrease of serum Mg levels during HD resulted in two uncrossed lines, the initial-values line being higher than terminal-values one (the higher the initial level the more pronounced was its decrease during HD). 2. Balanced effect of HD on the serum levels of Zn (low values increased, high levels decreased) represented two crossing-lines. 3. Significant increase of urine Mg in patients supplemented by Mg demonstrated two uncrossed lines. The position of initial-values curve was lower than the terminal-values one. The proposed graphical method of the evaluation of large amounts of data is simple and enables a quick orientation in the assessment of the effects of therapeutic interventions (trace elements, drugs and other relevant substances).

Adult↗
PubMed2003

Tissue factor, its pathway inhibitor, and metabolic disturbances in long-term peritoneal dialysis.

BACKGROUND/AIM: The tissue factor (TF) plays a key role in triggering the coagulation system in vivo. Our study was designed to determine whether or not the plasma levels of TF and its pathway inhibitor (TF pathway inhibitor; TFPI) in patients with chronic renal failure (CRF) treated by peritoneal dialysis (PD) (1) are pathologically altered; (2) differ between diabetics and nondiabetics, and (3) depend on the metabolic disorders associated with CRF and/or diabetes. METHODS: Using ELISA, plasma TF and TFPI levels were measured once in 21 PD patients (10 with diabetes, 11 without diabetes) and in 21 healthy subjects. RESULTS: As compared with healthy subjects (TF 282 pg/ml; TFPI 73 ng/ml), both TF and TFPI levels were significantly higher in PD patients with diabetes (485 pg/ml, p < 0.001, and 106 ng/ml, p < 0.01, respectively) and in PD patients without diabetes (480 pg/ml, p < 0,001, and 121 ng/ml, p < 0.001, respectively). The difference between diabetics and nondiabetics was not significant. In stepwise regression analysis, the TF levels depended on serum creatinine (partial correlation 0.39, p < 0.05), glycemia (0.43, p < 0.01), and insulin (-0.43, p < 0.05), and the TFPI levels depended on creatinine (partial correlation 0.67, p < 0.001), apolipoprotein B (0.46, p < 0.01), and plasma fibrinogen (0.43, p < 0.01). CONCLUSIONS: CRF patients on PD show increased plasma TF and TFPI levels. There is no difference between diabetics and nondiabetics. The TF and TFPI levels depend significantly on the renal function, as assessed by serum creatinine, and on some metabolic disorders. Elevated TF and TFPI levels may be related to thrombosis and atherosclerosis in CRF patients on PD.

Adult↗
PubMed2003

Free radicals after painful stimulation are influenced by antioxidants and analgesics.

OBJECTIVES: To study the balance between the pro-oxidative and antioxidative defence system after repeated painful stimulation in rats and the efficacy of the administration of different antioxidants (vitamins C, E, A, and selenium), analgesics (acetylsalicylic acid, morphine), and their combinations. METHODS: Mechanical clamping of both hind limbs was applied for 10 min for 5 consecutive days in adult male Wistar rats. The tail-flick latency was measured before and after a 5-day nociceptive stimulation with or without the substance application. The reactive oxygen species (ROS) were determined in the sensorimotor cortex. RESULTS: Painful stimulation increased lipoperoxidation which persisted for up to 15 days after it had been discontinued. A simultaneous injection of antioxidants decreased the levels of TBARS, SOD and GSHPx; however, antioxidants applied one week prior to the painful stimulation were ineffective. A simultaneous injection of analgesics reduced stress-induced analgesia caused by the nociceptive stimulation, but did not affect lipoperoxidation. CONCLUSIONS: A combination of antioxidants with analgesics normalized both the oxidative stress and functional (the tail-flick latency) indicators. These results suggest that the administration of antioxidants in pain treatment may be employed to decrease the doses of analgesics and to prevent the negative impact of reactive oxygen species on nociception.

Analgesics↗
PubMed2002

Does treatment modality have an impact on anemia in patients with chronic renal failure? Effect of low- and high-flux biocompatible dialysis.

Renal anemia significantly affects the morbidity and mortality of dialysis patients. The aim of the present study was to establish whether the severity of anemia and success of its treatment differs when using high-flux (HF) or low-flux (LF) hemodialysis. Twenty-five patients on long-term hemodialysis with a mean hematocrit (Hct) of 33%, S alb of 36 g/L, and Kt/V urea of 1.5 were divided into Groups X (n = 13) and Y (n = 12) in a prospective randomized crossover study. Group X was initially treated with LF hemodialysis to be followed by HF hemodialysis for 8 weeks each time. Group Y started with 8 week HF hemodialysis and continued, after crossover, with 8 weeks of LF hemodialysis. HF and LF hemodialysis were performed with polysulfone dialyzers F 7HPS and F60S (Fresenius Medical Care, Bad Homburg, Germany). Hct values, examined at 2 week intervals, did not differ significantly between Groups X and Y during 16 weeks of the study at any measuring interval. In another analysis, all results of HF hemodialysis (first 8 weeks of Y + second 8 weeks of X) were pooled as were all data of LF hemodialysis (first 8 weeks of X + second 8 weeks of Y). No significant relationships were noted between duration of treatment with HF hemodialysis and Hct (n = 72, rS = 0.11, p = 0.36) and between duration of LF hemodialysis and Hct (n = 74, rS = 0.02, p = 0.87) in the newly formed groups. The Hct measured during HF hemodialysis and LF hemodialysis did not differ significantly. Analysis of variance did not reveal a relationship between Hct and the HF or LF membrane. As HF and LF hemodialysis differed significantly in Kt/V urea, the variables were adjusted to identical Kt/V urea using analysis of covariance. No relationship between Hct and dialysis membrane permeability was demonstrated even in this case. Use of biocompatible LF and HF membranes in standard hemodialysis modes under conditions of adequate dose of dialysis and the time period studied did not result in different effects on anemia.

Aged↗
PubMed2002

Treatment of hyperhomocysteinemia with folic acid: effects on homocysteine levels, coagulation status, and oxidative stress markers.

The aim of the study was to determine whether folic acid treatment in subjects with homocysteinemia would change their coagulation and oxidative status. Thirty-three patients with peripheral vascular disease and 26 elderly subjects with no symptoms of atherosclerosis, all of whom had total homocysteine >20 microM, were treated with folic acid (5 or 10 mg) for 3 months. In the 33 patients with peripheral vascular disease, homocysteine levels decreased from a median of 26.7 microM at baseline to 20.0 microM (p < 0.0001), whereas in the 26 asymptomatic elderly subjects, homocysteine level decreased from 24.4 microM to 18.6 microM (p < 0.0001). Plasma fibrinogen decreased whereas plasminogen and anti-thrombin increased; the differences between pre- and posttreatment values were significant in both patients and healthy subjects. Oxidative status markers showed a shift toward lower oxidative stress. This effect was observed in both study groups. An association of the therapeutic effect with the genetic polymorphism of 5,10-methylenetetrahydrofolate reductase was not detected. Folic acid supplementation to hyperhomocysteinemic subjects resulted in a decrease in total blood homocysteine concentrations; moreover, there was a tendency to reverse the coagulation status and oxidative stress.

Aged↗
PubMed2002

First kidney transplantation from a non-heart-beating donor in the Czech Republic.

The long-lasting decline in the number of kidney donors with brain death in recent years is the reason for a quest for new sources of kidney donors in the Czech Republic. One possible source to increase the number of donor kidneys is the program of obtaining kidneys from non-heart-beating donors (NHBDs). Based on previous experience abroad, optimum hospital conditions, and, first of all, three years of experimental work, it was possible to realise an NHBD program for the first time in the Czech Republic, in the Transplant Centre of the Plzen Hospital in early 2002. The first two kidneys were obtained from a donor with a devastating gunshot brain injury (Maastricht criteria, Class III). After machine perfusion (RM3 renal perfusion system, Waters Medical) both kidneys were transplanted into two recipients with chronic renal insufficiency (chronic glomerulonephritis, nephrosclerosis). Both kidneys resumed their function immediately. For immunosuppression, basiliximab (Simulect, Novartis), rapamycin (Rapamune, Wyeth), and methylprednisolone (Urbason solubile forte, Hoechst) were used. To improve renal function, cyclosporine A (Sandimmune Neoral, Novartis) was started later in the course, simultaneously reducing the dose of rapamycin. The postoperative course was uneventful and both patients could be discharged on the twenty-first day of hospitalisation for further care at home.

Creatinine↗
PubMedDate not supplied

Parameters of oxidative stress in children with Type 1 diabetes mellitus and their relatives.

Oxidative stress (OS) plays an important role in the pathogenesis of Type 1 diabetes mellitus (DM). The aim of the study was to compare OS parameters in diabetic children and their first-degree relatives. Fifty diabetic children from the West Bohemian Region were examined as well as their 32 siblings (12 Boys and 20 girls) and 65 of their parents during a period of 6 months. Thirty healthy sex- and age-matched children studied before planned surgeries were normal controls for children, 40 healthy adult volunteers were controls for parents. OS parameters were evaluated in all participants of the study (superoxide dismutase, SOD; glutathione peroxidase, GSHPx; plasma antioxidant capacity, AOC; reduced glutathione, GSH; and malondialdehyde, MDA) and also Type 1 DM-associated antibodies (ICA and GADA). The results in diabetic children showed significantly lower GSHPx and AOC and increased MDA when compared with healthy children. Similar findings were found in their siblings but without statistical significance. It is consequently evident that decreased antioxidative protection and simultaneous free radical (FR) overproduction occur in diabetic children and that there is a similar, but not significant, tendency in their siblings. The findings warrant reducing OS in diabetic children and postponing disease onset in susceptible relatives.

Adolescent↗
PubMedDate not supplied

Composite veneers, crowns, and inlay bridges after orthodontic therapy--a three-year prospective study.

Composite veneers, crowns, and adhesive bridges also can be a part of interdisciplinary therapy, namely, cooperation between orthodontics and prosthodontics. This study sought to systematically analyze patients treated orthodontically and prosthodontically with permanent teeth from a long-term point of view (three years). Forty-nine composite veneers, crowns, and adhesive bridges were inserted on the anterior teeth of 20 patients as a part of reshaping and reorientation of teeth after orthodontic therapy. The results indicated that composite resin restoration, including fiber-reinforcement restoration, is the treatment of choice in anterior dentition.

Adult↗