High-frequency ultrasound is used in this study to measure noninvasively, by means of osmotic loading, changes in speed of sound and cartilage thickness caused by variations of the salt concentration in the external bath. Articular cartilage comprises three main structural components: Water, collagen fibrils and proteoglycan macromolecules carrying negative charges. The negatively charged groups of proteoglycans attract cations and water into tissue and govern its shrinkage/swelling behavior, which is a fundamental mechano-electrochemical function of cartilage tissue. In this study, the mechano-electrochemical behavior of cartilage is modeled by a diffusion model. The proposed model enables simulations of cartilage osmotic loading under various parameter settings and allows to quantify cartilage mechanical properties. This theoretical model is derived from the kinetic theory of diffusion. The objectives of the study are to quantify time dependent changes in cartilage thickness, and in speed of sound within tissue with help of the finite element based simulations and data from experiments. Experimental data are obtained from fresh and trypsinized ovine patella samples. Results show that the proposed diffusion model is capable to describe transient osmotic loading of cartilage. Mean values and their deviations of the relative changes of cartilage characteristics in response to chemical loading are presented.

• MeSH
• Models, Biological * MeSH
• Cartilage, Articular * diagnostic imaging   MeSH
• Osmosis MeSH
• Sheep MeSH
• Proteoglycans MeSH
• Ultrasonography MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

OBJECTIVES: Our previous experiments proved that methylprednisolone (MP) can significantly reduce axonal impairment accompanying extracellular oedema induced by the osmotic challenge (load) on the blood-brain barrier (BBB). The aim of the present work was to identify whether MP can affect myelin impairment accompanying intracellular oedema induced by water intoxication. METHODS: For induction of cellular brain oedema, the standard model of water intoxication was chosen. Animals received distilled water in amount corresponding to 15% of the animal's body weight. The volume was divided into three parts and administered intraperitoneally in 8 hours interval. Axonal changes were recognized as signs of myelin disintegration (oedematous distensions, axonal swelling, vesicles, varicosities) at histological sections stained with Black Gold and classified into four grades of myelin degradation. Hippocampal CA1 and CA3 areas and the dentate gyrus were selected for the study. Methylprednisolone was administered either intraperitoneally or intracarotically. Its effect was studied in two different time intervals: in the acute group (30 minutes after hyperhydration and MP application) and in chronic one (1 week after hyperhydration and MP application). Results: In both the acute and chronic groups, cellular oedema induced by water intoxication brought about apparent damage of myelin (compared to control animals p<0.0001). Intracarotic injection of MP was not able to influence myelin integrity changes either in the acute or in chronic group. However, intraperitoneal administration of MP increased the level of myelin deterioration in the acute group (p 0.05), but improved myelin changes in the chronic group (p<0.005). Conclusion: The effect of MP on axonal impairment during cellular brain oedema induced by water intoxication differs from that during the extracellular osmotic oedema. In the extracellular oedema, cellular metabolism is not significantly affected and myelin changes can be influenced by the neuroprotective effect of MP. The primary cause of cellular oedema is a disorder of cellular metabolism and myelin impairment is one of the structural consequences of such disorder. That is why the myelin changes are not affected by MP administration in a consistent and specific manner.

• MeSH
• Axons drug effects   metabolism   pathology   MeSH
• Brain Edema drug therapy   metabolism   pathology   MeSH
• Glucocorticoids pharmacology   MeSH
• Blood-Brain Barrier drug effects   metabolism   pathology   MeSH
• Water Intoxication drug therapy   metabolism   pathology   MeSH
• Rats MeSH
• Methylprednisolone pharmacology   MeSH
• Myelin Sheath drug effects   metabolism   pathology   MeSH
• Nerve Fibers, Myelinated drug effects   metabolism   pathology   MeSH
• Neuroprotective Agents pharmacology   MeSH
• Osmotic Pressure drug effects   MeSH
• Rats, Wistar MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Optimálně sestavený individualizovaný peritoneální dialyzační rozvrh je základním předpokladem dlouhodobě úspěšné peritoneální dialýzy. Stávající možnosti jsou rozšířené o novou modifikaci, adaptovanou APD. Za využití stejného času a stejných prostředků lze s tímto předpisem dosáhnout lepší ultrafiltrace. optimální clearance urey, kreatininu a fosforu. Další přínos této metody spočívá ve snížení množství absorbované glukózy z dialyzačního roztoku a tím snížení metabelické náleže pro pacienta.

Optimal and individualized schedule of dialysis solution exchanges in peritoneal dialysis represents a basic requirement for long-term peritoneal dialysis success. Existing modalities are now expaned by a novel modification, adapted automated peritoneal dialysis. Using the identical time and identical resources, adopted APD offers better ultrafiltration and optimal urea, creatinine and phosphate clearance. Another benefits of this new approach consist in the decreased amount of absorbed glucose from dialysis solution. This results in lowering of the metabolic load for the patient.

• MeSH
• Biological Transport, Active MeSH
• Glucose metabolism   standards   MeSH
• Hemodialysis Solutions * standards   MeSH
• Peritoneal Dialysis, Continuous Ambulatory * methods   standards   MeSH
• Humans MeSH
• Metabolic Clearance Rate MeSH
• Osmotic Pressure MeSH
• Peritoneum * MeSH
• Permeability MeSH
• Software MeSH
• Ultrafiltration * methods   standards   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Review MeSH

Biomechanics is one of the branches of science contributing significantly not only to increasing our knowledge of the development of living systems but also to our understanding of the relevant laws of mechanics and their mechanical functions. Important anatomical and biomechanical data as related to the individual functions of the organism and their biomechanical significance are focussed on in this publication. The locomotor and circulatory apparatus and the identification of the mechanical properties of living tissue and materials used in osteosynthesis and alloarthroplasty are among the fields covered. The phenomena observed in the cardiovascular system are described using the basic equation of motion of viscous fluids. Suitable hydraulic models are proposed for investigation and testing of vascular grafts, artificial cardiac valves and artificial heart. Important research data are presented about biomechanical structures of the locomotoric apparatus, and joint rheology. A section is included presenting the fundamentals of the biomechanical analysis in criminology and in bioballistics.

• Keywords
• systém kardiovaskulární - biomechanika - texty učební postgraduální,

• Conspectus
• Biochemie. Molekulární biologie. Biofyzika
• NML Fields
• fyzika, biofyzika
• fyziologie
• kardiologie
• angiologie

Long-term peritoneal dialysis is associated with alterations in peritoneal function, like the development of high small solute transfer rates and impaired ultrafiltration. Also, morphologic changes can develop, the most prominent being loss of mesothelium, vasculopathy, and interstitial fibrosis. Current research suggests peritoneal inflammation as the driving force for these alterations. In this review, the available evidence for inflammation is examined and a new hypothesis is put forward consisting of high glucose-induced pseudohypoxia. Hypoxia of cells is characterized by a high (oxidized-reduced nicotinamide dinucleotide ratio) NADH-NAD+ ratio in their cytosol. Pseudohypoxia is similar but occurs when excessive amounts of glucose are metabolized, as is the case for peritoneal interstitial cells in peritoneal dialysis. The glucose-induced high NADH-NAD+ ratio upregulates the hypoxia-inducible factor-1 gene, which stimulates not only the glucose transporter-1 gene but also many profibrotic genes like TGFβ, vascular endothelial growth factor, plasminogen activator inhibitor-1, and connective tissue growth factor, all known to be involved in the development of peritoneal fibrosis. This review discusses the causes and consequences of pseudohypoxia in peritoneal dialysis and the available options for treatment and prevention. Reducing peritoneal exposure to the excessively high dialysate glucose load is the cornerstone to avoid the pseudohypoxia-induced alterations. This can partly be done by the use of icodextrin or by combinations of low molecular mass osmotic agents, all in a low dose. The addition of alanyl-glutamine to the dialysis solution needs further clinical investigation.

• MeSH
• Dialysis Solutions adverse effects   metabolism   MeSH
• Glucose adverse effects   metabolism   MeSH
• Hypoxia MeSH
• Humans MeSH
• NAD * metabolism   MeSH
• Peritoneal Dialysis * adverse effects   MeSH
• Peritoneum metabolism   MeSH
• Vascular Endothelial Growth Factor A metabolism   MeSH
• Inflammation MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

Recent studies in humans and rats suggested that increased Na+ storage in the skin without parallel water retention may predispose to salt-sensitive hypertension. In the current studies, we compared tissue Na+ storage in salt sensitive spontaneously hypertensive rats (SHR) versus salt resistant normotensive Brown Norway (BN-Lx) rats. After salt loading (10 days drinking 1% NaCl solution), the SHR showed significant parallel increase in Na+-to-water as well as (Na++K+)-to-water ratios suggesting increased storage of osmotically inactive Na+ in the skin while no significant changes in skin electrolyte concentrations were observed in BN-Lx rats. SHR rats after salt treatment exhibited a nonsignificant decrease in skin blood capillary number (rarefaction) while BN-Lx rats showed significantly increased skin blood capillary density. Analysis of dermal gene expression profiles in BN-Lx rats after salt treatment showed significant up-regulation of genes involved in angiogenesis and proliferation of endothelial cells contrary to the SHR. Since the skin harbors most of the body's resistance vessels it is possible that blood capillary rarefaction may lead to increased peripheral resistance and salt sensitivity in the SHR.

• Publication type
• Journal Article MeSH

Icodextrin, polymer glukózy, je vedle glukózy alternativním osmotickým agens peritoneálně dialyzačních roztoků. Ultrafiltraci generuje na principu koloidní osmózy, a je proto účinný i při dlouhotrvajících (např. nočních) prodlevách a vysoké permeabilitě peritonea, kdy zabraňuje zpětné resorpci dialyzátu. Ultrafiltrace je udržena i při případné peritonitidě. Incidence bakteriální peritonitidy se při léčení icodextrinovým a glukózovým roztokem neliší. Při icodextrinu byl svého času pozorován zvýšený výskyt sterilní peritonitidy. Přičino u byla kontaminace některých šarží roztoku peptidoglykanem, což je součást buněčné stěny grampozitivních bakterií. Exaktními izotopovými metodami bylo prokázáno, že léčení icodextrinovým roztokem zlepšuje stav hydratace peritoneálně dialyzovaných nemocných, což dává předpoklad pro snazší kontrolu krevního tlaku. Při dialýze s icodextrinem dochází ke snížení masy levé komory. Akutní hemodynamické účinky icodextrinu zatím vzhledem k metodickým problémům provedených studií není možné jednoznačně interpretovat. Pokud je do preskripce peritoneální dialýzy zařazen místo glukózového icodextrinový roztok, snižuje se metabolická zátěž glukózou, což může příznivě ovlivnit hyperlipidemii, hyperinzulinemii, hyperleptinemii, u diabetiků navíc i kontrolu glykemie. Funkce peritonea jako dialyzační membrány je při léčení icodextrinovým roztokem stabilní, pravděpodobně déle než při léčení glukózovými roztoky. Data z rozsáhlého registru dokladují nižší mortalitu nemocných léčených icodextrinem, to však bude muset být potvrzeno v prospektivních randomizovaných kontrolovaných studiích.

Icodextrin, a glucose polymer, is an alternative osmotic agent to glucose in peritoneal dialysis solutions. Icodextrin generates ultrafiltration through colloid osmosis and is thus effective even during long-term (e.g., nighttime) dwells and in cases of high peritoneal permeability, where it prevents dialysate reabsorption into the systemic circulation. Ultrafiltration is maintained even in the presence of peritonitis. The incidence of bacterial peritonitis is not different when using icodextrin- or glucose-based solutions. Some time ago, icodextrin use was implicated in an increased incidence of sterile peritonitis. This was due to contamination of some batches of the solution by peptidoglycan present in the cell wall of G+ bacteria. Using exact isotope methods, treatment with icodextrin-based solution has been shown to improve the hydration status of peritoneal dialysis patients, suggesting a potential for improved blood pressure control. Icodextrin-based dialysis is associated with a reduction of left ventricular mass. Given the methodological flaws of trials conducted to date, the acute hemodynamic effects of icodextrin cannot be conclusively interpreted. Inclusion of icodextrin-based solution instead of the glucose-based one into the prescription of peritoneal dialysis decreases the metabolic load with glucose potentially having a beneficial effect on hyperlipidemia, hyperinsulinemia and hyperleptinemia, with improved glycemic control in patients with diabetes as an additional benefit. Function of the peritoneum as a dialysis membrane is stable during icodextrin-based treatment, possibly longer compared with glucose-based solutions. Data derived from a large-scale registry have shown lower mortality oficodextrin-treated patients; this, however, needs to be confirmed by prospective randomized controlled trials.

• MeSH
• Glucans adverse effects   MeSH
• Glucose adverse effects   MeSH
• Hemodialysis Solutions adverse effects   MeSH
• Hemodynamics MeSH
• Humans MeSH
• Peritoneal Dialysis MeSH
• Peritoneum metabolism   MeSH
• Peritonitis etiology   MeSH
• Ultrafiltration MeSH
• Water-Electrolyte Balance MeSH
• Check Tag
• Humans MeSH

Východisko. Blokátory cyklooxygenázy 2 (COX-2) jsou často užívanými léky u pacientů s degenerativními poruchami pohybové ústrojí. Většinou jde o starší nemocné s chronickými nefropatiemi. Cílem naší studie bylo zjištění účinku specifické blokády COX-2 rofecoxibem na ledvinové funkce u starších pacientů se středně významnou poruchou ledvinové funkce. Metody a výsledky. Použili jsme běžných vyšetřovacích metod jednak za podmínek vyrovnaného metabolizmu vody a soli, jednak za podmínek submaximální vodní diurézy. Vyšetřovali jsme glomerulární filtraci zjišťovanou pomocí clearance kreatininu, inulínu (Cin) a cystatinu C, frakční exkreci (FE) elektrolytů, všech osmoticky aktivních látek, vody a bezsolutové vody a celkové močové vylučování prostaglandinů UPGE2V a UPGF2αV. Zjišťovali jsme plazmatickou reninovou aktivitu (PRA) a aldosteron (Paldo) po stimulaci ortostatickou polohou. Při porovnání nálezů před versus po léčbě rofecoxibem jsme zjistili: Cin 0,82±0,34 vs 0,74±0,18 ml/s/1,73m2, FENa 1,0±0,3 vs 1,2±0,4 (p=0,02), FEOSM 2,9±0,7 vs 3,7±1,2 % (p=0,03), UPGE2αV 663±528 vs 414±195 (p=0,059), UPGF2V (559±625) vs 205±174 ηg/24 h (p=0,02), stimulovanou PRA 0,94±0,73 vs 0,4±0,27 ±pg/l/h (p=0,019), Paldo 104,56±50,15 vs 56,94±27,08 ηg/l/h (p=0,008). Závěry. Naše nálezy nasvědčují tomu, že u nemocných s poruchou ledvinové funkce může specifická inhibice COX-2 za definovaných podmínek snížit tubulární transport sodíku, aniž by změnila GFR a vylučování vody.

Background. Elderly patients suffering from nociceptive pain of locomotive organs and concomitantly from renal impairment represent a target population for painkilling drugs. That is why they are predisposed to nephrotoxic effects non-steroidal anti-inflammatory drugs. The aim of our study was to evaluate cycloxygenase-2 (COX-2) inhibition effect on renal function in elderly with moderate impairment of renal function. Methods and Results. Based on 24-h urine collection we assessed creatinine clearance (CCr), fractional excretion of sodium (FENa), potassium (FEK), chloride (FECl), osmotic active solutes (FEOSM) and 24h urinary excretion of prostaglandin PGE2 and PGF2α. Under conditions of sub-maximal water load fractional excretion of electrolytes, inulin clearance (Cin), serum cystatin C (Scyst) were assessed. In addition basal and stimulated plasma renin activity (PRA) and plasma aldosteron (Paldo) were examined. Using comparison of parameters before and at the end of 7-days rofecoxib treatment we found out Cin 0,82±0,34 vs 0,74±0,18 ml/s/1,73 m2, FENa 1,0±0,3 vs 1,2±0,4 (p=0,02), FEOSM 2,9±0,7 vs 3,7±1,2 % (p=0,03), UPGE2αV 663±528 vs 414±195 (p=0,059), UPGF2V (559±625) vs 205±174 ηg/24h (p=0,02), stimulated PRA 0,94±0,73 vs 0,4±0,27 ±pg/l/h (p=0,019), Paldo 104,56±50,15 vs 56,94±27,08 ηg/l/h (p=0,008). Conclusions. Short-term COX-2 inhibition in patients with moderate renal impairment was associated with significant decrease of tubular transport of sodium, without changing GFR and water excretion.

• MeSH
• Arthralgia drug therapy   complications   MeSH
• Kidney Failure, Chronic complications   metabolism   MeSH
• Cyclooxygenase Inhibitors pharmacology   adverse effects   MeSH
• Humans MeSH
• Aged MeSH
• Check Tag
• Humans MeSH
• Aged MeSH

• MeSH
• Physiology MeSH
• Publication type
• Congress MeSH
• Collected Work MeSH

• Conspectus
• Fyziologie člověka a srovnávací fyziologie
• NML Fields
• fyziologie