Institute of Medical Biology

Martin, Slovakia

Institute of Medical Biology

Martin, Slovakia

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Filseth O.M.,Institute of Medical Biology | Filseth O.M.,University of Tromsø | How O.-J.,Institute of Clinical Medicine | How O.-J.,Institute of Medical Biology | And 5 more authors.
Critical Care Medicine | Year: 2012

Objective: Inotropic drugs are frequently administered in hypothermic Patients to support an assumed inadequate circulation, but their pharmacologic properties at reduced temperatures are largely unknown. Thus we estimated dopamine pharmacokinetics as well as left ventricular function and global hemodynamics after dopamine infusions at various core temperatures in a pig model of surface cooling and rewarming. Design: Prospective, randomized, open, placebo-controlled experimental study. Setting: University-affiliated animal research laboratory. SUBJECTS: Sixteen healthy, anesthetized juvenile (2-3 months) castrated male pigs. Interventions: After normothermic infusions of dopamine at different doses (4, 8, and 16 μg/kg/min), effects of dopamine (n = 8) or saline (n = 8) were tested at 25°C and during rewarming (30-34°C). Measurements and Main Results: Dopamine half-time was 5.4 ± 0.7 min at normothermia, increased to 11.6 ± 0.8 min at 25°C, but returned to control during rewarming at 34-35°C. Dopamine infusion at 25°C elevated dopamine plasma concentration four-fold compared to the same infusion rate at normothermia, leading to increased systemic vascular resistance index not seen at normothermia. Also, in contrast to the dopamine-mediated increase in cardiac index observed at normothermia, high-dose dopamine at 25°C left cardiac index unchanged despite a concomitant increase in heart rate, since stroke index decreased by 43%. During rewarming, cardiovascular effects of dopamine at moderate hypothermia (30-34°C) were principally similar to responses during normothermia. Conclusions: Pharmacodynamic effects and pharmacokinetics of dopamine are Maintained during the rewarming phase at moderate hypothermia. However, at 25°C dopamine pharmacokinetics were seriously altered and dopamine failed to increase cardiac index since stroke index was reduced with incrementing dosages. Properties of the low-flow, high-viscosity circulatory state, combined with altered pharmacokinetics of dopamine, may explain lack of beneficial -and potentially harmful -effects from dopamine administration at 25°C. © 2012 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins.


Hjelmevoll S.O.,University Hospital of North Norway | Olsen M.E.,University Hospital of North Norway | Sollid J.U.E.,Institute of Medical Biology | Haaheim H.,University Hospital of North Norway | And 5 more authors.
Acta Dermato-Venereologica | Year: 2012

Culture is commonly regarded as the gold standard for diagnosis of Neisseria gonorrhoeae. However, nucleic acid amplification tests (NAATs) have rapidly replaced culture for diagnostics in many settings. The aim of the present study was to investigate the appropriate time for test-of-cure (TOC) when NAATs are used for diagnosis of gonorrhoea. In total, 30 patients (28 men and 2 women) provided urethral, cervical, rectal or pharyngeal specimens for TOC. All included patients, except one who did not return for second TOC before day 19, tested negative within 2 weeks after treatment with cefixime 400 mg × 1. Antimicrobial susceptibility testing showed that 68% of the culture-positive strains were resistant to ciprofloxacin. Thus, the recommended empirical treatment with ciprofloxacin in Norway should be changed immediately. TOC can be performed 2 weeks after treatment when NAATs are used for diagnosis of gonorrhoea. © 2012 The Authors.


Kohler R.,Institute of Medical Biology | Kaistha B.P.,Institute of Medical Biology | Kaistha B.P.,University of Marburg | Wulff H.,Institute of Medical Biology | Wulff H.,University of California at Davis
Expert Opinion on Therapeutic Targets | Year: 2010

Importance of the field: Cardiovascular disease is a leading cause of death in modern societies. Hyperpolarizing Ca2+-activated K+ channels (KCa) are important membrane proteins in the control of arterial tone and pathological vascular remodelling and thus could serve as new drug targets. Areas covered in this review: We summarize recent advances in the field of vascular KCa and their roles in cardiovascular pathologies such as hypertension and restenosis disease and draw attention to novel small-molecule channel modulators and their possible therapeutic utility. This review focuses on literature from the last four to five years. What the reader will gain: Pharmacological opening of endothelial KCa3.1/ KCa2.3 channels stimulates endothelium-derived-hyperpolarizing-factormediated arteriolar dilation and lowers blood pressure. Inhibition of smooth muscle KCa3.1 channels has beneficial effects in restenosis disease and atherosclerosis. We consider the therapeutic potential of KCa3.1/KCa2.3 openers as novel endothelium-specific antihypertensive drugs as well as of KCa3.1- blockers for the treatment of pathological vascular remodelling and discuss advantages and disadvantages of the pharmacotherapeutic approaches. Take home message: Pharmacological manipulation of vascular KCa channels by novel small-molecule modulators offers new venues for alternative treatments of hypertension, restenosis and atherosclerosis. Additional efforts are required to optimize these compounds and to validate them as cardiovascular-protective drugs. © 2010 Informa UK Ltd ISSN.


PubMed | Yong In University, National University of Singapore and Institute of Medical Biology
Type: | Journal: Journal of visualized experiments : JoVE | Year: 2016

The glycoprotein family of collagens represents the main structural proteins in the human body, and are key components of biomaterials used in modern tissue engineering. A technical bottleneck is the deposition of collagen in vitro, as it is notoriously slow, resulting in sub-optimal formation of connective tissue and subsequent tissue cohesion, particularly in skin models. Here, we describe a method which involves the addition of differentially-sized sucrose co-polymers to skin cultures to generate macromolecular crowding (MMC), which results in a dramatic enhancement of collagen deposition. Particularly, dermal fibroblasts deposited a significant amount of collagen I/IV/VII and fibronectin under MMC in comparison to controls. The protocol also describes a method to decellularize crowded cell layers, exposing significant amounts of extracellular matrix (ECM) which were retained on the culture surface as evidenced by immunocytochemistry. Total matrix mass and distribution pattern was studied using interference reflection microscopy. Interestingly, fibroblasts, keratinocytes and co-cultures produced cell-derived matrices (CDM) of varying composition and morphology. CDM could be used as bio-scaffolds for secondary cell seeding, where the current use of coatings or scaffolds, typically from xenogenic animal sources, can be avoided, thus moving towards more clinically relevant applications. In addition, this protocol describes the application of MMC during the submerged phase of a 3D-organotypic skin co-culture model which was sufficient to enhance ECM deposition in the dermo-epidermal junction (DEJ), in particular, collagen VII, the major component of anchoring fibrils. Electron microscopy confirmed the presence of anchoring fibrils in cultures developed with MMC, as compared to controls. This is significant as anchoring fibrils tether the dermis to the epidermis, hence, having a pre-formed mature DEJ may benefit skin graft recipients in terms of graft stability and overall wound healing. Furthermore, culture time was condensed from 5 weeks to 3 weeks to obtain a mature construct, when using MMC, reducing costs.


PubMed | Pacific Northwest Research Institute, University of Washington and Institute of Medical Biology
Type: | Journal: G3 (Bethesda, Md.) | Year: 2016

Aneuploidy, a state in which the chromosome number deviates from a multiple of the haploid count, significantly impacts human health. The phenotypic consequences of aneuploidy are believed to arise from gene expression changes associated with the altered copy number of genes on the aneuploid chromosomes. To dissect the mechanisms underlying altered gene expression in aneuploids, we used RNA-seq to measure transcript abundance in colonies of the haploid Saccharomyces cerevisiae strain F45 and two aneuploid derivatives harboring disomies of chromosomes XV and XVI. F45 colonies display complex fluffy morphologies, while the disomic colonies are smooth, resembling laboratory strains. Our two disomes displayed similar transcriptional profiles, a phenomenon not driven by their shared smooth colony morphology nor simply by their karyotype. Surprisingly, the environmental stress response (ESR) was induced in F45, relative to the two disomes. We also identified genes whose expression reflected a non-linear interaction between the copy number of a transcriptional regulatory gene on chromosome XVI, DIG1, and the copy number of other chromosome XVI genes. DIG1 and the remaining chromosome XVI genes also demonstrated distinct contributions to the effect of the chromosome XVI disome on ESR gene expression. Expression changes in aneuploids appear to reflect a mixture of effects shared between different aneuploidies and effects unique to perturbing the copy number of particular chromosomes, including non-linear copy number interactions between genes. The balance between these two phenomena is likely to be genotype and environment specific.


News Article | September 9, 2016
Site: phys.org

Nick Barker's team at A*STAR's Institute of Medical Biology studied the development of flask-shaped pockets in the lining of the stomach's pyloric region, known as pyloric glands, which secrete gastrin and mucus into the stomach. Within each gland is a dividing pool of stem cells that contributes to two essential processes. Some of the daughter cells remain undifferentiated and slowly replace other stem cells within the gland, while others migrate upwards and differentiate to renew the stomach lining relatively rapidly. The researchers used stochastic models to study these two processes, using observations of fluorescently labeled cells to fit the models. Since stem cells divide and replace other stem cells, eventually all of the cells in a gland will have descended from a single stem cell. To investigate this process, the team extended an earlier model that assumed the process starts with a single stem cell, rather than a pool. By building a model without this assumption, the team discovered that only a few of the stem cells are in a position for their descendants to effectively expand to the entire gland. The researchers also quantified the renewal of the stomach lining by stem cell proliferation and differentiation. By integrating stochastic models and experiments they showed that the processes of proliferation and differentiation are tightly coupled; stem cells normally divide at the same rate as their daughters differentiate, ensuring that the pool remains the same size. The team also applied this approach to quantify stem cell proliferation and differentiation under conditions that resembled disease, when these processes become uncoupled. These models will help understand gastric diseases as well as normal pyloric gland development. "For instance, we can examine whether gastric cancer is the result of an imbalance between stem cell proliferation and differentiation or is associated with a slower replacement of stem cells, meaning that faulty stem cells are not replaced early enough" says Carmen Pin, a visiting researcher from the Institute of Food Research in the UK who undertook the study with Barker and Marc Leushacke from the A*STAR team. "The same approach could be used to study the dynamics of any population of cells which can be genetically labeled and traced in other organs," they added.  Explore further: A protein biomarker confirms the presence of stem cells that maintain ovaries More information: Marc Leushacke et al. Quantifying Lgr5-positive stem cell behaviour in the pyloric epithelium, Scientific Reports (2016). DOI: 10.1038/srep21923 Provided by: Agency for Science, Technology and Research (A*STAR), Singapore


Ho per A.C.,Institute of Medical Biology | Salma W.,Institute of Medical Biology | Sollie S.J.,Institute of Medical Biology | Hafstad A.D.,Institute of Medical Biology | And 5 more authors.
Journal of Nutrition | Year: 2014

We showed previously that dietary supplementation with oil from the marine zooplankton Calanus finmarchicus (Calanus oil) attenuates obesity, inflammation, and glucose intolerance in mice. More than 80% of Calanus oil consists of wax esters, i.e., long-chain fatty alcohols linked to long-chain fatty acids. In the present study, we compared the metabolic effects of Calanus oil-derived wax esters (WE) with those of purified eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) ethyl esters (E/D) in a mouse model of diet-induced obesity. C57BL/6J mice received a high-fat diet (HFD; 45% energy from fat). After 7 wk, the diet was supplemented with either 1% (wt:wt) WE or 0.2% (wt:wt) E/D. The amount of EPA + DHA in the E/D diet was matched to the total amount of n-3 (ω-3) polyunsaturated fatty acids (PUFAs) in the WE diet. A third group was given an unsupplemented HFD throughout the entire 27-wk feeding period. WE reduced body weight gain, abdominal fat, and liver triacylglycerol by 21%, 34%, and 52%, respectively, and significantly improved glucose tolerance and aerobic capacity. In abdominal fat depots, WE reduced macrophage infiltration by 74% and downregulated expression of proinflammatory genes (tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1), whereas adiponectin expression was significantly upregulated. By comparison, E/D primarily suppressed the expression of proinflammatory genes but had less influence on glucose tolerance thanWE. E/D affected obesity parameters, aerobic capacity, or adiponectin expression by <10%. These results show that the wax ester component of Calanus oil can account for the biologic effects shown previously for the crude oil. However, these effects cannot exclusively be ascribed to the content of n-3 PUFAs in the wax ester fraction. © 2014 American Society for Nutrition.


Bartos V.,Faculty Hospital in Zilina | Adamicova K.,Institute of Pathological Anatomy | Kullova M.,Faculty Hospital in Zilina | Pec M.,Institute of Medical Biology
Klinicka Onkologie | Year: 2012

Background: Basal cell carcinoma (BCC) recurrences are relatively frequent event in a routine dermatologic practice. One of the most important factor which impacts risk of their development is a histomorphological appearance of tumor. Design: The purpose of our study was to compare histological types of primary and corresponding relapsing BCCs of the skin. Material and methods: The study included 36 cases of BCC recurrences from 34 patients, 17 women and 17 men. The patients ranged in age from 32 to 97 years, with a mean age of 67.1 years at the time of (the first) recurrence. Results: Both tumor groups generally exhibited the same proportion of indolent and aggressive histological phenotype. In 21 cases (58.4%), we found an identical histological BCC type in primary and subsequent relapsing lesion. In 3 cases (8.3%), primary lesion showed indolent histological features without aggressive-growth component, while recurrent tumor already manifested it. Conversely, in next 3 cases (8.3%) primary tumor exhibited focal infiltrative-growth features and corresponding relapsing lesion did not. Of the remainig 9 cases (25%), histomorpological phenotype was not identical, but it showed the same prognostic histological tumor variant. Conclusion: Based on the results of our study it can be assumed that a BCC recurrence is a dynamic histogenetic process, during which the phenotypic transformation and the changes in histomorphological picture of lesions occur, probably as a result of the interactions between cancer cells and re-modulated surrounding stroma.


Kohler R.,Institute of Medical Biology
Pflugers Archiv European Journal of Physiology | Year: 2010

In the cardiovascular system, Ca2+-activated K +-channels (KCa) are considered crucial mediators in the control of vascular tone and blood pressure by modulating the membrane potential and shaping Ca2+-dependent contraction. Vascular smooth muscle cells express the BKCa channel which fine-tunes contractility by providing a negative feedback on Ca2+-elevations. BKCa channel's ionconducting β-subunit is encoded by the KCa1.1 gene, and the accessory and Ca2+-sensitivity modulating β1-subunit is encoded by the KCNMB1 gene. Vascular endothelial cells express the calmodulin-gated KCa channels IKCa (encoded by the KCa3.1 gene) and SKCa (encoded by the KCa2.3 gene). These two channels mediate endothelial hyperpolarization and initiate the endothelium-derived hyperpolarizing factor-dilator response. Considering these essential roles of KCa in arterial function, mutations in KCa genes have been suspected to contribute to cardiovascular disease in humans. So far, DNA sequence analysis in the population and patient cohorts has identified single-nucleotide polymorphisms (SNPs) in the BKCa β1-subunit gene as well as in the α-subunit gene (KCa1.1). Some of these SNPs produce amino acid exchanges and evoke alterations of channel functions ("gain-of-function" as well as "loss-offunction"). Moreover, the epidemiological studies showed that the presence of the E65K polymorphism in, e.g., BKCa β1-subunit gene (producing a "gain-of-function") lowers the prevalence for severe hypertension and myocardial infarction. Other SNPs in the BKCa α-subunit gene and also in the KCa3.1 gene expressed in the endothelium have been suggested to increase the risk of cardiovascular disease. These findings from sequence analysis of human KCa genes, and epidemiological studies thus provide evidence that genetic variations and mutations in KCa channel genes contribute to human cardiovascular disease. © Springer-Verlag 2009.


Stewart C.L.,Institute of Medical Biology
Nucleus (Austin, Tex.) | Year: 2014

Pairing of homologous chromosome is a unique event in meiosis that is essential for both haploidization of the genome and genetic recombination. Rapid chromosome movements during meiotic prophase are a key feature of the pairing process. This is usually telomere-led, and in metazoans is dependent upon microtubules and dynein. Chromosome movements culminate in the formation of a meiotic "bouquet" in which nuclear envelope-associated telomeres are clustered at the centrosomal pole of the nucleus. Bouquet formation is thought to facilitate homolog pairing. Recent studies reveal that coupling of telomeres to cytoplasmic dynein is mediated by SUN1 in the inner nuclear membrane (INM) and KASH5 a novel protein of the outer nuclear membrane (ONM). Together SUN1 and KASH5 assemble to form a transluminal LINC (linker of the nucleoskeleton and cytoskeleton) complex that spans both nuclear membranes. SUN1 forms attachment sites for telomeres at the INM while KASH5 functions as a dynein adaptor at the ONM. In mice deficient in KASH5, homologous chromosome pairing does not occur. The result is that meiosis is arrested at the leptotene/zygotene stage of meiotic prophase 1, and as a consequence both male and female mice are infertile. This study demonstrates an essential role for dynein directed telomere movement during meiotic prophase.

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