ECM is composed of different collagenous and non-collagenous proteins. Collagen nanofibers play a dominant role in maintaining the biological and structural integrity of various tissues and organs, including bone, skin, tendon, blood vessels, and cartilage. Artificial collagen nanofibers are increasingly significant in numerous tissue engineering applications and seem to be ideal scaffolds for cell growth and proliferation. The modern tissue engineering task is to develop three-dimensional scaffolds of appropriate biological and biomechanical properties, at the same time mimicking the natural extracellular matrix and promoting tissue regeneration. Furthermore, it should be biodegradable, bioresorbable and non-inflammatory, should provide sufficient nutrient supply and have appropriate viscoelasticity and strength. Attributed to collagen features mentioned above, collagen fibers represent an obvious appropriate material for tissue engineering scaffolds. The aim of this minireview is, besides encapsulation of the basic biochemical and biophysical properties of collagen, to summarize the most promising modern methods and technologies for production of collagen nanofibers and scaffolds for artificial tissue development., L. Koláčná, J. Bakešová, F. Varga, E. Košťáková, L. Plánka, A. Nečas, D. Lukáš, E. Amler, V. Pelouch., and Obsahuje bibliografii
This work evaluates the myocardial protective potential of potassium cardioplegia on ischaemically arrested and reperfused hearts by two cardioplegic solutions: the University of Wisconsin solution (UW) and the standard crystalloid solution of St. Thomas’ Hospital (ST). Evaluation of myocardial preservation was based on creatine kinase and lactate releases and on high-energy phosphate preservation of isolated rabbit hearts after 4 hours’ hypothermic ischaemia. A morphometric ultrastructural evaluation of mitochondria in cardiomyocytes was also performed. The hearts of 24 rabbits were normothermally perfused with oxygenated Krebs-Henseleit solution for 30 min (Langendorff preparation), and the baseline contractile performance and biochemical parameters were evaluated. The hearts were then arrested and stored in the cardioplegic solutions (12 UW and 12 ST) at 4 °C for 4 hours. The hearts were then rewarmed and reperfused with oxygenated Krebs-Henseleit solution for further 30 min. At the end of reperfusion, creatine phosphate and high energy phosphates were higher with UW (p<0.05); creatine kinase release during reperfusion was significantly lower with UW both at 15 min (p<0.01) and at 30 min (p<0.05). Lactate release during the first 15 min of reperfusion was about doubled (p<0.05) with respect to controls in both groups; at 30 min this increase had almost vanished ( + 8 %) with UW but not with ST ( + 30 %). Ultrastructural morphometry did not show any significant difference at the level of mitochondria between the two treatments. The results indicate, for UW, an improved myocardial preservation associated with relative retention of high-energy phosphates and higher recovery of mechanical function, accelerated metabolic recovery and reduced stress of cell membranes.
The objective of this study was to investigate the early biological response in the olive flounder exposed to sub-lethal concentrations of waterborne phenanthrene (0.5, 1 or 2 μM). The fish were exposed for 4 weeks and we analyzed their enzymatic defense system, antioxidant and phase II enzyme activities, to evaluate the chronic exposure toxicity of phenanthrene. Waterborne phenanthrene affected antioxidant enzymes and glutathione-mediated detoxification as an enzyme defense system. Hepatic, gill and kidney glutathione reductase as well as glutathione S-transferase, and catalase activities were markedly elevated after two or four weeks of exposure. These enzyme activities of the olive flounder, Paralichthys olivaceus, seem to be a convenient approach for monitoring pollution in coastal areas against polycyclic aromatic hydrocarbon pollution including phenanthrene.
The aim of our study was to evaluate potential differences in the concentration of biochemical markers of endothelial dysfunction between essential hypertension, endocrine hypertension (pheochromocytoma, primary hyperaldosteronism) and control healthy group and to assess a potential relationship between these markers of endothelial dysfunction and
vasopressor substances overproduced in endocrine hypertension. We have investigated 21 patients with moderate essential hypertension, 29 patients with primary hyperaldosteronism, 24 subjects with pheochromocytoma and 26 healthy volunteers. Following parameters of endothelial dysfunction were measured, von Willebrand factor (vWf),
plasminogen activator (t-PA) and E-selectin (E-sel). Clinical blood pressure was measured according to the European Society of Hypertension recommendations. We found significantly higher levels of the von Willebrand factor in patients with essential hypertension in comparison with a control group (114±20 IU/dl vs 90±47 IU/dl; P=0.04) and patients with primary hyperaldosteronism (114±20 IU/dl vs 99±11 IU/dl; P=0.01). Patients with endocrine hypertension revealed increased levels of vWF compared to the control group, but these differences did not reach statistical significance. Levels of t-PA were increased in patients with pheochromocytoma in comparison with the control group (4.6±1.9 ng/ml vs 3.4±0.9 ng/ml; P=0.01) and with primary hyperaldosteronism (4.6±1.9 ng/ml vs 3.4±1.1 ng/ml; P<0.01). In case of E-selectin we found lower levels in patients with pheochromocytoma in comparison with other
groups, but they differed significantly only with primary hyperaldosteronism (40.2±15.0 ng/ml vs 51.3±23.0 ng/ml; P=0.05). Our study did not reveal any convincing evidence of differences in the levels of biochemical markers of endothelial dysfunction between essential and endocrine hypertension. No correlation between the biochemical markers of endothelial dysfunction and vasopressor substances activated in endocrine hypertension was found.
The well-known bottleneck of systems pharmacology, i. e., systems biology applied to pharmacology, refers to the model parameters determination from experimentally measured datasets. This paper represents the development of our earlier studies devoted to inverse (ill-posed) problems of model parameters identification. The key feature of this research is the introduction of control (or periodic forcing by an input signal being a drug intake) of the nonlinear model of drug-induced enzyme production in the form of a system of ordinary differential equations. First, we tested the model features under periodic dosing, and subsequently, we provided an innovative method for a parameter estimation based on the periodic dosing response measurement. A numerical example approved the satisfactory behavior of the proposed algorithm.
Regulace příjmu potravy a nutričního stavu organismu je komplexní děj, který se odehrává na úrovni několika orgánových systémů. Centrálním regulátorem je hypothalamus, který integruje nervové a hormonální signály z periferie a monitoruje sérové hladiny glukózy a lipidů. V hypothalamu se nacházejí neurony produkující jak orexigenní hormony zvyšující příjem potravy (neuropeptid Y, agouti-related protein, orexiny), tak anorexigenní hormony, které působí opačným mechanismem (proopiomelanokortin, kokainem a amfetaminem regulovaný transkript). Gastrointestinální trakt je místem produkce především anorexigenních regulačních hormonů (cholecystokinin, oxyntomodulin, bombesin), které zpětnovazebně prostřednictvím cirkulace a vagových zakončení ovlivňují hypothalamická centra. Jediným orexigenním peptidem tvořeným v trávicím traktu je ghrelin. Pankreatické hormony (inzulin, pankreatický polypeptid, amylin), které ovlivňují glukózový metabolismus, regulují také příjem potravy a nutriční stav organismu přímým působením na CNS i nepřímo prostřednictvím ovlivnění glykémie. Pohled na tukovou tkáň jako na pasivní úložiště energie je již překonán. Adipocyty produkují řadu hormonálně aktivních látek, které se podílejí jak na regulaci tělesné hmotnosti (leptin), tak insulinové senzitivity (adiponektin, rezistin). Sérové hladiny uvedených regulačních hormonů reagují dynamicky jak na příjem potravy, tak na celkový nutriční stav organismu. Jejich periferní nebo centrální aplikace působí změnu příjmu potravy a u některých z nich byla již vyvinuta syntetická analoga, u kterých se předpokládá využití v léčbě poruch výživy u člověka. Proto jsou tyto hormony vhodné ke studiu z pohledu klinické biochemie jako potencionální biomarkery., Regulation of food intake and nutritional status is a complex process which takes place in several organ systems. Hypothalamus is the central regulator that integrates signals from the nervous system and peripheral hormones and monitors serum levels of glucose and lipids. In the hypothalamus, there are neurons producing both orexigenic hormones that increase food intake (neuropeptide Y, agouti-related protein, orexins), and anorexigenic hormones, that act in antagonistic way (proopiomelanocortin, cocaine- and amphetamine-regulated transcript). Gastrointestinal tract is mainly the source of anorexigenic regulatory hormones (cholecystokinin, oxyntomodulin, bombesin), that influence hypothalamic centres by both circulation and vagal nerves. The only orexigenic peptide produced by gastrointestinal tract is ghrelin. Pancreatic hormones (insulin, pancreatic polypeptide, amylin), that influence glucose metabolism, regulate also food intake and nutritional status of the organism both by direct action on CNS and indirectly through changes of glycaemia. Adipose tissue is not considered a passive place of energy stores anymore. Adipocytes produce quite a number of hormonally active substances that participate in the regulation of body weight (leptin), and insulin sensitivity (adiponectin, resistin). Serum levels of above-mentioned regulatory hormones are dynamically influenced both by food intake, and general nutritional status of the organism. Peripheral or central administration leads to changes in food intake and for some of them synthetic analogues are being developed with potential future use in treatment of nutritional disorders. Thus, these hormones are suitable for studies in the field of clinical biochemistry as potential biomarkers., Jiří Bronský, Richard Průša, and Lit.: 35
Many extracellular signals are at the cell surface received by specific receptors, which upon activation transduce information to the appropriate cellular effector molecules via trimeric G proteins. The G protein-mediated cascades ultimately lead to the highly refined regulation of systems such as sensory perception, cell growth, and hormonal regulation. Transmembrane signaling may be seriously deranged in various pathophysiological conditions. Over the last two decades the major experimental effort of our group has been devoted to better understanding the molecular mechanisms underlying transmembrane signaling regulated by G proteins and to the closely related process of desensitization of hormone response. This review provides general information about the basic principles of G protein-regulated transmembrane signaling as well as about our contribution to the current progress in the field.
Spinal cord injury results in a permanent neurological deficit due to tissue damage. Such a lesion is a barrier for “communication” between the brain and peripheral tissues, effectors as well as receptors. One of the primary goal s of tissue engineering is to bridge the spinal cord injury and re-establish the damaged connections. Hydrogels are biocompatible implants used in spinal cord injury repair. They can create a permissive environment and bridge the lesion cavities by providing a scaffold for the regeneration of neurons and their axons, glia and other tissue elements. The advantage of using artificial materials is the possibility to modify their physical and chemical properties in order to develop the best implant suitable for spinal cord injury repair. As a result, several types of hydrogels have been tested in experimental studies so far. We review our work that has been done during the last 5 years with various types of hydrogels and their applications in experimental spinal cord injury repair., A. Hejčl, P. Lesný, M. Přádný, J. Michálek, P. Jendelová, J. Štulík, E. Syková., and Obsahuje bibliografii a bibliografické odkazy