Pavel Zivny

Epidemiology of Helicobacter pylori Infection in the Czech Republic

Background:  Prevalence of Helicobacter pylori infection has been estimated to range from 60 to 95% in the former communist countries of Central and Eastern Europe. The aim of this study was to evaluate H. pylori infection prevalence in a representative sample of the Czech population. The second objective was to describe difference of H. pylori prevalence between different social groups of children and adults.

Impact of cardiopulmonary bypass on peripheral tissue metabolism and microvascular blood flow.

The aim of this study was to monitor and compare the changes in metabolism and blood flow in the skeletal muscles during cardiac operations performed with cardiopulmonary bypass (CPB) and operations without CPB (off-pump) by means of interstitial microdialysis (Figure 1). Surgical revascularization, coronary artery bypass grafting (CABG), was performed in 40 patients randomized to two groups. Twenty patients (On-Pump Group) were operated on using CPB, 20 patients (Off-Pump Group) were operated on without CPB. Interstitial microdialysis was performed by 2 probes of a CMA 60 (CMA Microdialysis AB, Solna, Sweden) inserted into the patient’s deltoid muscle. Microdialysis measurements were performed at 30-minute intervals. Glucose, lactate, pyruvate and glycerol as markers of basic metabolism and tissue perfusion were measured in samples from the first probe, using a CMA 600 Analyzer (CMA Microdialysis AB). Blood flow through the interstitium was monitored by means of dynamic microdialysis of ethanol as a flow-marker in the dialysates taken from the second probe (ethanol dilution technique). Results in both the groups were statistically processed and compared. Both the groups were similar in respect of preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in both the patient groups (on-pump vs. off-pump) during the operation. There was no significant difference in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate and glycerol interstitial concentrations, lactate/pyruvate ratio and lactate/glucose ratio between the on-pump vs. off-pump patients. In the Off-Pump Group, pyruvate concentrations were higher and the values of concentrations of glycerol lower. The lactate/pyruvate ratio and the lactate/glucose ratio, indicating the aerobic and anaerobic tissue metabolism status, were lower in the Off-Pump Group. There was no significant difference in dialysate concentrations of ethanol as a flow-marker during the surgery in either of the groups. There was no statistically significant difference between the groups (On-Pump Group vs. Off-Pump Group) comparing the postoperative clinical outcome (ICU stay, ventilation duration, length of hospital stay). The dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both the groups of patients (On-Pump Group and Off-Pump Group), but there was no difference in local blood flow when the ethanol dilution technique was used. These results showed significantly higher aerobic metabolic activity of the peripheral tissue of patients in the Off-Pump Group vs. the On-Pump Group during the course of cardiac revascularization surgery. Results suggest that extracorporeal circulation, cardiopulmonary bypass, compromises peripheral tissue (skeletal muscles) energy metabolism. These changes have no impact on the postoperative clinical outcome; no significant difference between the groups was found.

New high-performance liquid chromatography method for the determination of (R)-warfarin and (S)-warfarin using chiral separation on a glycopeptide-based stationary phase.

Warfarin is a well-known anticoagulant agent that occurs in two enantiomers, (R)-(+)-warfarin and (S)-(-)-warfarin. A new liquid chromatography method for the determination of both enantiomers was developed, validated and applied in in vitro studies with the aim of evaluating the accumulation of (R)-warfarin and (S)-warfarin in the hepatoma HepG2 cell line. OptiMEM cell cultivation medium samples and cellular lysates were purified using Waters Oasis MAX extraction cartridges. The chiral separation of warfarin and the internal standard p-chlorowarfarin enantiomers was performed on an Astec Chirobiotic V2 column at a flow rate of 1.2mL/min. The mobile phase was composed of 31% acetonitrile, 5% of methanol and 64% of ammonium acetate buffer (10mmol/L, pH 4.1). The enantiomers were quantified using a fluorescence detector (lambda(excit)=320nm, lambda(emiss)=415nm). The limit of detection was found to be 0.121micromol/L of (S)-warfarin and 0.109micromol/L of (R)-warfarin. The range of applicability and linearity was estimated from 0.25 to 100micromol/L. The precision ranged from 1.3% to 12.2% of the relative standard deviation, and the accuracy reached acceptable values from 95.5% to 108.4%. The new bioanalytical method confirmed the same accumulation of (R)-warfarin and (S)-warfarin in the hepatoma HepG2 cell line.

The effect of levetiracetam on rat bone mass, structure and metabolism.

OBJECTIVE To determine the effect of levetiracetam (LEV) Lon bone mineral density (BMD), mineral content (BMC), bone markers, body composition and bone mechanical strength in the orchidectomised (ORX) rat model. METHOD 16 orchidectomised Wistar rats were divided into control and test groups, 8 rats in each group. The control rats received standard laboratory diet (SLD) while rats in the test group were fed with SLD enriched with LEV for 12 weeks. BMD was measured by dual energy X-ray absorptiometry at the whole body, lumbar spine and femur. Bone marker concentrations were examined of osteoprotegerin (OPG) and insulin-like growth factor 1 (IGF-1) in serum, and amino-terminal propeptide of procollagen type I (PINP), carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I), bone alkaline phosphatase (ALPL), and bone morphogenetic protein 2 (BMP-2) in bone homogenate. The femurs were used for biomechanical testing. RESULTS Compared to the control group we found lower fat mass, lower BMD in the area of the left femur, lower BMC in both femurs, a reduced concentration of OPG, and an increased concentration of CTX-I of borderline statistical significance (p=0.0661). Biomechanical parameters did not differ between groups. CONCLUSIONS Significant loss of BMD or BMC was seen at the left and right femur area in the LEV group. Administration of LEV in the ORX-rat model significantly decreased levels of OPG (marker of bone formation) in serum and increased levels of CTX-I (marker of bone resorption) in bone homogenate, but results in this study did not reveal any change in biomechanical bone strength. Administration of LEV in the ORX-rat model may reduce adipose tissue. Further studies in animals and humans will be needed to confirm these findings.

Protective Effect of Amlodipine on Rat Bone Tissue after Orchidectomy

Aim: Our study aimed to investigate the effect of amlodipine on bone metabolism in orchidectomized rats. Methods: Eight-week-old rats were divided into three groups. The sham-operated control group (SHAM) and the control group after orchidectomy (ORX) received the standard laboratory diet (SLD). The experimental group after orchidectomy (ORX+AML) received SLD enriched with amlodipine for 12 weeks. Bone marker concentrations in serum of PINP, OPG and IGF-1, and the levels of CTX-I, BAP and BMP-2 in a bone homogenate were measured using enzyme-linked immunosorbent assay. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The femurs were used for biomechanical testing. Results: Bone markers (CTX-I, BAP, BMP-2) in ORX were higher versus SHAM. In ORX+AML there was a decrease in PINP, CTX-I, BAP, BMP-2 and OPG versus ORX. IGF-1 was decreased in ORX versus SHAM. In ORX+AML it was increased versus ORX. In ORX, a decrease was demonstrated versus SHAM in BMD of the whole body, in the lumbar vertebrae and in both femurs. In ORX+AML there was an increase in BMD of the whole body versus ORX. Three-point bending test revealed a decrease in maximal load values in ORX versus SHAM. After amlodipine administration there was an increase in the left femur versus ORX. Conclusions: Amlodipine is capable of mitigating the negative effects of orchidectomy and could be a good prevention of osteoporosis.

Influence of high cholesterol diet and pravastatin sodium on the initiation of liver regeneration in rats after partial hepatectomy.

OBJECTIVES Liver regeneration is influenced by cholesterol and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-reductase). HMG-CoA-reductase is a key enzyme for cholesterol synthesis. Recent studies have shown that inhibitors of HMG-CoA-reductase improve liver functions after 67% partial hepatectomy (PH). METHODS Male Wistar rats (W) and Prague hereditary hypercholesterolemic rats (PHHC) were used. Aqua pro injectione (AI) or pravastatin (prava; 1 mg/kg) was administered orally once daily. Group 1: W, standard diet (SD) + AI; group 2: W, SD + prava; group 3: W, cholesterol-enriched diet (chol) + AI; group 4: PHHC, chol + AI; group 5: PHHC, chol + prava. After 27 d, PH was performed in all groups. RESULTS Groups fed chol before PH had significantly higher liver triacylglycerol content (group 3: 25.8 +/- 2.6 mg/g of liver weight; group 4: 16.0 +/- 1.0 of liver weight; group 5: 22.0 +/- 1.0 of liver weight) than did the groups fed SD (group 1: 6.1 +/- 0.5; group 2: 5.9 +/- 0.7). Liver DNA synthesis after PH was significantly lower in chol-fed groups (group 3: 561 +/- 78; group 4: 472 +/- 92) than in SD-fed groups (group 1: 1645 +/- 574; group 2: 2935 +/- 1298), except the chol-fed PHHC given prava (group 5: 3230 +/- 527). CONCLUSIONS In prava-treated rats, the induction of HMG-CoA activity overcame the inhibitory capability of pravastatin. The induction of HMG-CoA-reductase activity had a stimulatory effect on the initiation of liver regeneration.

Protective effect of atorvastatin on bone tissue in orchidectomised male albino Wistar rats.

Recent studies have shown that atorvastatin influences bone metabolism. We investigated its bone protective effect in orchidectomised rats after 12 weeks of treatment. Eight-week-old rats were divided into 3 groups: sham-operated group, control group after orchidectomy and experimental group after orchidectomy with atorvastatin administration (12 mg/kg/day). Bone mineral density and bone marker concentrations of aminoterminal propeptide of procollagen type I (PINP), osteoprotegerin (OPG), insulin-like growth factor 1 (IGF-1) in serum, and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I), bone alkaline phosphatase (BALP), bone morphogenetic protein 2 (BMP-2) in bone homogenate were measured. Total serum calcium and tibial calcium content was determined. Femurs were used for three-point bending test of the shaft and compression testing of the femoral neck. Bone markers (CTX-I, BALP, BMP-2) in control rats were higher vs. sham-operated rats. Atorvastatin reduced CTX-I, BMP-2 and OPG compared to controls. IGF-1 was decreased in control rats vs. sham-operated rats; atorvastatin increased IGF-1 vs. control rats. Atorvastatin exerts a positive effect on bone metabolism by increasing bone mineral density of the whole body, which had decreased under the effects of orchidectomy. Three-point bending test revealed an increase in maximal load values of the left femurs after atorvastatin administration compared to controls. The diameter of the left femur and length of both femurs were increased after atorvastatin administration compared to controls. Our findings suggest that atorvastatin has a beneficial effect on bone metabolism in orchidectomised rats by decreasing bone turnover, with resulting improvement in bone mineral density and bone biomechanical properties.

Changes of cholinesterase activities in the plasma and some tissues following administration of l-carnitine and galanthamine to rats

Changes of acetylcholinesterase (AChE) activities in the hypophysis and brain (frontal cortex, hippocampus, medial septum and basal ganglia), and butyrylcholinesterase in plasma and liver following galanthamine (GAL) administration were studied in rats pretreated with L-carnitine (CAR). Following only GAL administration (10 mg/kg, i.m.), both cholinesterases (without clinical symptoms of GAL overdosage) were significantly inhibited. Pretreatment with CAR (3 consecutive days, 250 mg/kg, p.o.) followed by GAL administration showed higher AChE inhibition in comparison with single GAL administration. However, a statistically significant difference was observed for AChE in the hippocampus only. The activity of peripheral cholinesterases was not influenced by CAR pretreatment. Thus, pretreatment with CAR enhanced AChE inhibition in some brain parts of the rat following GAL administration.

Serum leptin concentrations after surgery in young rats

OBJECTIVES We describe changes in serum leptin concentrations after surgery (laparotomy, partial hepatectomy, splenectomy, and unilateral nephrectomy) in young male rats. Because we presumed that pain and inflammation would influence food intake and subsequent leptin release, laparotomized and partially hepatectomized rats were treated with ibuprofen. METHODS Preoperative blood samples were taken from the retroorbital sinuses, and postoperative blood samples were taken from the aorta, vena portae, and vena cava 18 h after surgery. Serum leptin concentrations were estimated by radioimmunoassay. RESULTS Pre- and postoperative serum leptin concentrations did not differ significantly in rats with partial hepatectomy (5.1 +/- 0.4 versus 4.2 +/- 1.1 microg/L), splenectomy (6.1 +/- 0.4 versus 5.0 +/- 0.6 microg/L), or unilateral nephrectomy (4.1 +/- 0.7 versus 5.0 +/- 1.3 microg/L). Significant decreases in serum leptin were observed after laparotomy (8.1 +/- 0.9 versus 3.7 +/- 0.5 microg/L), laparotomy plus ibuprofen treatment (8.9 +/- 1.6 versus 3.1 +/- 0.4 microg/L), and partial hepatectomy plus ibuprofen treatment (5.4 +/- 0.6 versus 3.2 +/- 0.3 microg/L). We observed no significant differences in serum leptin concentrations measured in different regions of the body. CONCLUSIONS Surgical interventions in young rats are accompanied by decreases in serum leptin. The liver, spleen, and kidney may participate in leptin clearance. Ibuprofen treatment leads to additional decreases in serum leptin concentrations.

The effect of topiramate and lamotrigine on rat bone mass, structure and metabolism

There is only limited data concerning the effect of the newer antiepileptic drugs on bone. The objective of this study was to determine the effect of topiramate (TPM) and lamotrigine (LTG) monotherapy on bone mineral density (BMD), mineral content (BMC), bone markers, body composition and bone mechanical strength in the orchidectomized (ORX) rat model. 24 orchidectomized Wistar rats were divided into control and test groups, 8 rats in each group. The control rats received standard laboratory diet (SLD) while rats in the test group were fed with SLD enriched with LTG or TPM for 12 weeks. Dual energy X-ray absorptiometry was used to measure bone mineral density. The concentrations of bone metabolism markers were assayed in bone homogenate. In addition, both femurs were measured and used for biomechanical testing. Compared to the control group, both test groups had significantly lower weight, fat mass, whole body and femur BMD, BMC and reduced mechanical strength of bone. All of these changes were more pronounced in rats exposed to LTG. In conclusion, both LTG and TPM significantly reduce BMD and body weight and impair mechanical strength of bone. A question arises as to the degree of dependence of the effect on the dose. Further studies are warranted to establish whether LTG and TPM may have a clinically significant effect on BMD exclusively in the model of gonadectomized rats, or whether the effect applies also in the model of gonadally intact animals, and in the respective human models.