P Rossmann

Academy of Sciences of the Czech Republic, Praha, Praha, Czech Republic

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Publications (129)195.19 Total impact

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    ABSTRACT: Polymer drug carriers that are based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers have been widely used in the development and synthesis of high-molecular-weight (HMW) drug delivery systems for cancer therapy. In this study, we compared linear (Mw ~27kDa, Rh ~4nm) and non-degradable star (Mw ~250kDa, Rh ~13nm) HPMA copolymer conjugates bearing anthracycline antibiotic doxorubicin (DOX) bound via pH-sensitive hydrazone bond. We determined the in vitro and in vivo toxicity of both conjugates and their maximum tolerated dose (MTD). We also compared their anti-tumour activity in mouse B-cell leukaemia (BCL1) and a mouse T-cell lymphoma (EL4) model. We found that MTD was higher for the linear conjugate (85mgDOX/kg) and lower for the star conjugate (22.5mgDOX/kg). An evaluation of the intestinal barrier integrity using FITC-dextran as a gut permeability tracer proved that no pathology was caused by the MTD of either conjugate. However, free DOX showed some damage to the gut barrier. The therapy of BCL1 leukaemia by both of the polymeric conjugates using the MTD or its fraction (i.e., equitoxic dosage) showed better results in the case of the star conjugate. On the other hand, treatment of EL4 lymphoma seemed to be more efficient when the linear conjugate was used. We suppose that the anti-cancer treatment of solid tumours and leukaemias requires different types of drug conjugates. We hypothesise that the most suitable HPMA copolymer-DOX conjugate for the treatment of solid tumours should have an HMW structure with increased Rh that would be stable for three to four days after the conjugate administration and then rapidly disintegrate in the short polymer chains, which are excretable from the body by glomerular filtration. On the other hand, the treatment of leukaemia requires a drug conjugate with a long circulation half-life. This would provide an active drug, whilst slowly degrading to excretable fragments.
    Full-text · Article · Dec 2015 · Journal of Controlled Release
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    ABSTRACT: The tube-within-tube body plan of earthworms is appropriate for studying the interactions of microorganisms with the immune system of body cavities such as the digestive tract and coelom. This study aims to describe the immune response on the molecular and cellular level in the coelomic cavity and the gut of the earthworm Eisenia andrei after experimental microbial challenge by administering two bacterial strains (E. coli and B. subtilis) or yeast S. cerevisiae to the environment. The changes in mRNA levels of defense molecules (pattern recognition receptor CCF, lysozyme, fetidin/lysenins) in the coelomocytes and gut tissue were determined by quantitative PCR. The immune response at a cellular level was captured in histological sections, and the expression of CCF was localized using in situ hybridization. Coelomocytes respond to the presence of bacteria in the coelomic cavity by increasing the mRNA levels of defense molecules, especially CCF. The immune response in gut tissue is less affected by microbial stimulation because the epithelial cells of gut exhibit basically strong mRNA synthesis of ccf as a defense against the continuous microbial load in the gut lumen. The cellular immune response is mediated by coelomocytes released from the mesenchymal lining of the coelomic cavity. These combined immune mechanisms are necessary for the survival of earthworms in the microbially rich environment of soil.
    No preview · Article · Dec 2015 · Developmental and comparative immunology
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    ABSTRACT: Here we present the polymer conjugates where the core formed by poly(amido amine) dendrimers was grafted with semitelechelic N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers containing docetaxel (DTX) attached by a pH-sensitive hydrazone bond. DTX was derivatized with three different keto acids prior to attachment to the polymer carrier to introduce reactive keto groups into the drug. The therapeutic efficacy of such high-molecular-weight star conjugates is based on: a) the Enhanced Permeability and Retention (EPR) effect facilitating selective accumulation within solid tumors; b) pH-controlled release of the drug, thus ensuring faster DTX release in the mildly acidic tumor microenvironment. The star DTX conjugate had a remarkably higher maximum tolerated dose in comparison to free DTX when administered as a single i.v. injection (~ 160 mg/kg vs. 40 mg/kg of DTX) in C57BL/6 mice. The star DTX conjugate showed significantly higher antitumor activity than free drugDTX in the EL4 T cell lymphoma growing in syngeneic C57BL/6 mice even when given at the same dose (20 mg/kg of DTX eq.). Thus, the star DTX conjugates exert a much higher therapeutic activity yet lower systemic toxicity than free DTX.
    Full-text · Article · Sep 2014
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    ABSTRACT: Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) belong to the group of persistent organic pollutants, highly toxic environmental pollutants that include hydrophobic compounds with the tendency to bioaccumulate. Earthworms (Eisenia andrei) were exposed to PCDD/Fs-contaminated soil, and changes in their lipophilic structures and the gene expression of their defense molecules were followed. Damage to the intestinal wall and adjacent chloragogenous tissue was observed. Further, the up-regulation of the expression of several genes was detected. On the basis of these results, the mechanism of the impact of PCDD/Fs on earthworms has been proposed. Dioxins that accumulate in the lipophilic structures cause an increase in reactive oxidative species that triggers oxidative stress followed by the gene expression of two molecules that play a role in protection against oxidant toxicity, calreticulin (CRT) and Hsp70. Moreover, the effect of microbial biomass on the expression of coelomic cytolytic factor (CCF), a pattern recognition receptor, was also observed.
    Full-text · Article · Jun 2014 · Environmental Pollution
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    ABSTRACT: Immunocompatibility of gelatin-based hydrogels to be applied as implant coatings for local regenerative treatment has been studied. First, the bio- and immunoacceptability of the methacrylamide-modified gelatin hydrogels per se was screened. The results indicated that the hydrogels support cell growth. Metabolic activity of normal cells and permanent cell lines representing various cell types (endothelial, epithelial, fibroblast, monocyte/macrophage) cultivated on the gelatin hydrogels was moderately lower compared to cells cultivated on tissue culture plastic. The cells cultivated on the hydrogels produced identical cytokines as the control cells although at lower levels. Importantly, no inflammatory activity, measured by nitric oxide and pro-inflammatory cytokine (IL-1α, IL-6, TNFα) production, was observed in peritoneal cells and monocyte/macrophage RAW 264.7 cell line cultivated on the hydrogels. Finally, polyimide (PI) implantable membranes were surface-modified with gelatin hydrogels and screened for their in vivo immunocompatibility. Their histological examination performed after subcutaneous implantation in mice produced a sound proof of immunoacceptability. Normal tissue repair, mild cellular infiltration and oedema mainly induced by the surgery were observed after 2 and 6 days. No adverse tissue responses were induced by the implants. Analysis performed after 4 and 9 weeks indicated areas of foreign body granuloma without formation of a fibrous capsule.
    No preview · Article · Jun 2014 · Journal of Biomedical Materials Research Part A
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    ABSTRACT: Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) belong to the group of persistent organic pollutants, highly toxic environmental pollutants that include hydrophobic compounds with the tendency to bioaccumulate. Earthworms (Eisenia andrei) were exposed to PCDD/Fs-contaminated soil, and changes in their lipophilic structures and the gene expression of their defense molecules were followed. Damage to the intestinal wall and adjacent chloragogenous tissue was observed. Further, the up-regulation of the expression of several genes was detected. On the basis of these results, the mechanism of the impact of PCDD/Fs on earthworms has been proposed. Dioxins that accumulate in the lipophilic structures cause an increase in reactive oxidative species that triggers oxidative stress followed by the gene expression of two molecules that play a role in protection against oxidant toxicity, calreticulin (CRT) and Hsp70. Moreover, the effect of microbial biomass on the expression of coelomic cytolytic factor (CCF), a pattern recognition receptor, was also observed.
    No preview · Article · Jan 2014
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    Full-text · Article · Oct 2013 · Molecular Biology Reports
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    ABSTRACT: Altered expression and methylation pattern of tumor suppressor and DNA repair genes, in particular involved in mismatch repair (MMR) pathway, frequently occur in primary colorectal (CRC) tumors. However, little is known about (epi)genetic changes of these genes in precancerous and early stages of CRC. The aim of this pilot study was to analyze expression profile and promoter methylation status of important tumor suppressor and DNA repair genes in the early stages of experimentally induced colorectal carcinogenesis. Rats were treated with azoxymethane (AOM), dextran sodium sulphate (DSS) or with their combination, and sacrificed 1 or 4 months post-treatment period. The down-regulation of Apc expression in left colon, detectable in animals treated with DSS-AOM and sacrificed 1 month after the end of treatment, represents most early marker of the experimental colorectal carcinogenesis. Significantly reduced gene expressions were also found in 5 out of 7 studied MMR genes (Mlh1, Mlh3, Msh3 Pms1, Pms2), regarding the sequential administration of DSS-AOM at 4 months since the treatment. Strong down-regulation was also discovered for Apc, Apex1, Mgmt and TP53. Tumors developed in rectum-sigmoid region displayed significantly lower Apc and Pms2 expressions. The decreased expression of studied genes was not in any case associated with aberrant methylation of promoter region. Present data suggest that down-regulation of Apc and MMR genes are prerequisite for the development of CRC. In this study we addressed for the first time early functional alterations of tumor suppressor genes with underlying epigenetic mechanisms in experimentally induced CRC in rats.
    No preview · Article · Sep 2013 · Molecular Biology Reports
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    ABSTRACT: Background: Microbial sensing by Toll-like receptors (TLR) and its negative regulation have an important role in the pathogenesis of inflammation-related cancer. In this study, we investigated the role of negative regulation of Toll-like receptors signaling and gut microbiota in the development of colitis-associated cancer in mouse model. Methods: Colitis-associated cancer was induced by azoxymethane and dextran sodium sulfate in wild-type and in interleukin-1 receptor-associated kinase M (IRAK-M)-deficient mice with or without antibiotic (ATB) treatment. Local cytokine production was analyzed by multiplex cytokine assay or enzyme-linked immunosorbent assay, and regulatory T cells were analyzed by flow cytometry. Changes in microbiota composition during tumorigenesis were analyzed by pyrosequencing, and β-glucuronidase activity was measured in intestinal content by fluorescence assay. Results: ATB treatment of wild-type mice reduced the incidence and severity of tumors. Compared with nontreated mice, ATB-treated mice had significantly lower numbers of regulatory T cells in colon, altered gut microbiota composition, and decreased β-glucuronidase activity. However, the β-glucuronidase activity was not as low as in germ-free mice. IRAK-M-deficient mice not only developed invasive tumors, but ATB-induced decrease in β-glucuronidase activity did not rescue them from severe carcinogenesis phenotype. Furthermore, IRAK-M-deficient mice had significantly increased levels of proinflammatory cytokines in the tumor tissue. Conclusions: We conclude that gut microbiota promotes tumorigenesis by increasing the exposure of gut epithelium to carcinogens and that IRAK-M-negative regulation is essential for colon cancer resistance even in conditions of altered microbiota. Therefore, gut microbiota and its metabolic activity could be potential targets for colitis-associated cancer therapy.
    Full-text · Article · Apr 2013 · Inflammatory Bowel Diseases
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    Full-text · Dataset · Feb 2013
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    ABSTRACT: This is a wrong sequence of authors! Look at the full text, there it is correct. JK
    Full-text · Dataset · Feb 2013

  • No preview · Article · Jan 2013 · International Journal of Molecular Medicine

  • No preview · Article · Jan 2013 · International Journal of Molecular Medicine
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    ABSTRACT: Purpose: Human colostrum and milk provide a newborn with immunomodulatory components, ensuring protection and proper development of the immune system. Secretory IgA antibodies in colostrum represent the first line of defence against harmful substances, but their potential spectra of reactivity with autoantigens remains unclear. Here, we characterised the repertoire of natural sectretory IgA autoantibodies in colostrum of healthy mothers. Methods: The human colostrum samples from 39 healthy mothers were analyzed for autoantibodies by indirect immunofluorescence, dot blots, immunoblots and ELISA. Results: We found that there is high diversity in reactivities of colostral IgA antibodies to autoantigens among individual samples. Using tissue sections and biochips commonly used for autoimmunity testing, we found that most samples reacted with monkey ovary (79.3%), monkey pancreatic tissue (78.6%), human HEp-2 cells (69%) and monkey adrenal gland (69.0%), fewer samples reacted with monkey liver tissue (47.2%), rat stomach (42.9%), monkey testicular tissue (41.4%), monkey salivary gland (39.3%), rat kidney (32.1%) and monkey cerebellar tissue (17.9%). At the protein level, we detected reactivity of IgA with 21 out of 25 (auto) antigens. The majority of the samples reacted with the pyruvate dehydrogenase complex, E3 ubiquitin ligase, cytosolic liver antigen, promyelocytic leukemia protein and nuclear pore glycoprotein-210. Using ELISA, we found reactivity of colostral IgA antibodies against examined extractable nuclear antigens, double stranded DNA, phospholipids and neutrophil cytoplasm. Conclusions: The broad spectrum of polyreactive natural autoantibodies present in human colostrum may contribute to proper development of mucosal immune system of the breastfed infant.
    No preview · Article · Jul 2012 · Journal of Clinical Immunology
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    ABSTRACT: Probiotic bacteria can be used for the prevention and treatment of human inflammatory diseases including inflammatory bowel diseases (IBD). However, the nature of active components and exact mechanisms of this beneficial effects have not been fully elucidated. Our aim was to investigate if lysate of probiotic bacterium L. casei DN-114 001 (Lc) could decrease the severity of intestinal inflammation in a murine model of IBD. The preventive effect of oral administration of Lc significantly reduces the severity of acute dextran sulfate sodium (DSS) colitis in BALB/c but not in SCID mice. In order to analyze how this beneficial effect interferes with well-known phases of intestinal inflammation pathogenesis in vivo and in vitro, we evaluated intestinal permeability using the FITC-labeled dextran method and analysed tight junction proteins expression by immunofluorescence and PCR. We also measured CD4(+)FoxP3(+) regulatory T cells proportion by FACS analysis, microbiota composition by pyrosequencing, and local cytokine production by ELISA. Lc leads to a significant protection against increased intestinal permeability and barrier dysfunction shown by preserved ZO-1 expression. We found that the Lc treatment increases the numbers of CD4(+)FoxP3(+) regulatory T cells in mesenteric lymph nodes (MLN), decreases production of pro-inflammatory cytokines TNF-α and IFN-γ, and anti-inflammatory IL-10 in Peyer's patches and large intestine, and changes the gut microbiota composition. Moreover, Lc treatment prevents lipopolysaccharide-induced TNF-α expression in RAW 264.7 cell line by down-regulating the NF-κB signaling pathway. Our study provided evidence that even non-living probiotic bacteria can prevent the development of severe forms of intestinal inflammation by strengthening the integrity of intestinal barrier and modulation of gut microenvironment.
    Full-text · Article · Nov 2011 · PLoS ONE
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    ABSTRACT: Oral thiopurines are effective and widely used in treatment of inflammatory bowel disease (IBD) in humans, although their use is limited due the development of adverse events. Here, we examine the efficacy and toxicity of oral treatment with 6-tioguanine (6-TG) and azathioprine (AZA) in a murine model of IBD. We induced acute or chronic colitis in BALB/c mice by one or four cycles of 3% dextran sulphate sodium (DSS), respectively. Mice were treated by daily gavages of various dosages of 6-tioguanine, azathioprine, or by phosphate buffered saline (PBS) starting the first day of DSS or after two cycles of DSS, respectively. We monitored the efficacy and toxicity by measuring the weight change and serum alanine aminotransferase (ALT) activity and by disease severity and histology, at the end of the experiment. Moreover, we measured cytokine production after colon fragment cultivation by enzyme-linked immunoabsorbent assay and numbers of apoptotic cells in the spleen by flow cytometry. 6-TG is effective in the treatment of acute DSS-induced colitis in a dose-dependent manner and 40 μg of 6-TG is significantly more effective in the treatment of acute colitis than both AZA and PBS. This effect is accompanied by decrease of IL-6 and IFN-γ production in colon. We did not observe histological abnormalities in liver samples from control (PBS) or 6-TG treated mice. However, liver samples from most mice treated with AZA showed mild, yet distinct signs of hepatotoxicity. In chronic colitis, all thiopurine derivatives improved colitis, 20 μg of 6-TG per dose was superior. High doses of 6-TG led to significant weight loss at the end of the therapy, but none of the thiopurine derivatives increased levels of serum ALT. Both thiopurine derivatives reduced the proportion of apoptotic T helper cells, but a high production of both IL-6 and TGF-β was observed only in colon of AZA-treated mice. Use of 6-TG in the treatment of experimental colitis in mice appears superior to AZA administration and placebo. In contrast to 6-TG, the use of AZA resulted in histological liver abnormalities.
    Full-text · Article · May 2011 · BMC Gastroenterology
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    ABSTRACT: Subretinal implants aim to replace the photoreceptor function in patients suffering from degenerative retinal disease by topically applying electrical stimuli in the subretinal space. Critical obstacles in the design of high-resolution subretinal implants include the proximity of stimulating electrodes to the target cells and enabling nutrient flow between the retina and the choroid. The present work evaluates the adhesion, migration and survival of retinal cells on an ultrathin (5 μm), highly porous (Ø 1 μm spaced 3 μm), gelatin-coated polyimide (PI) membrane. The biocompatibility was examined in mice indicating a good tolerance upon subcutaneous implantation with only a mild inflammatory response. In addition, organotypic cultures of rat retina evidenced that the porous membrane allowed the necessary nutrient flow for the retinal cell survival and maintenance. A transscleral implantation technique was applied to position the membrane into the subretinal space of rats. The effect on the obtained retinal integration was investigated in vivo using scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT). In 12 out of 18 rat eyes, the implant was successfully placed subretinally. SLO and OCT demonstrated complete retinal attachment and fluorescein angiography showed no retinal vascular abnormalities over and around the implant, immediately after and up to four weeks after the implantation. Histological examination of the eyes showed a close attachment of a thin fibrocyte layer to the implant, the occlusion of the pores by living cells and the survival of some photoreceptors at the implantation site.
    No preview · Article · Mar 2011 · Biomaterials
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    ABSTRACT: Metagenomic approaches are currently being used to decipher the genome of the microbiota (microbiome), and, in parallel, functional studies are being performed to analyze the effects of the microbiota on the host. Gnotobiological methods are an indispensable tool for studying the consequences of bacterial colonization. Animals used as models of human diseases can be maintained in sterile conditions (isolators used for germ-free rearing) and specifically colonized with defined microbes (including non-cultivable commensal bacteria). The effects of the germ-free state or the effects of colonization on disease initiation and maintenance can be observed in these models. Using this approach we demonstrated direct involvement of components of the microbiota in chronic intestinal inflammation and development of colonic neoplasia (i.e., using models of human inflammatory bowel disease and colorectal carcinoma). In contrast, a protective effect of microbiota colonization was demonstrated for the development of autoimmune diabetes in non-obese diabetic (NOD) mice. Interestingly, the development of atherosclerosis in germ-free apolipoprotein E (ApoE)-deficient mice fed by a standard low-cholesterol diet is accelerated compared with conventionally reared animals. Mucosal induction of tolerance to allergen Bet v1 was not influenced by the presence or absence of microbiota. Identification of components of the microbiota and elucidation of the molecular mechanisms of their action in inducing pathological changes or exerting beneficial, disease-protective activities could aid in our ability to influence the composition of the microbiota and to find bacterial strains and components (e.g., probiotics and prebiotics) whose administration may aid in disease prevention and treatment.Keywords: allergy; hygiene hypothesis; intestinal permeability; leaky gut; probiotics
    Preview · Article · Jan 2011 · Cellular & molecular immunology
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    ABSTRACT: Metagenomic approaches are currently being used to decipher the genome of the microbiota (microbiome), and, in parallel, functional studies are being performed to analyze the effects of the microbiota on the host. Gnotobiological methods are an indispensable tool for studying the consequences of bacterial colonization. Animals used as models of human diseases can be maintained in sterile conditions (isolators used for germ-free rearing) and specifically colonized with defined microbes (including non-cultivable commensal bacteria). The effects of the germ-free state or the effects of colonization on disease initiation and maintenance can be observed in these models. Using this approach we demonstrated direct involvement of components of the microbiota in chronic intestinal inflammation and development of colonic neoplasia (i.e., using models of human inflammatory bowel disease and colorectal carcinoma). In contrast, a protective effect of microbiota colonization was demonstrated for the development of autoimmune diabetes in non-obese diabetic (NOD) mice. Interestingly, the development of atherosclerosis in germ-free apolipoprotein E (ApoE)-deficient mice fed by a standard low-cholesterol diet is accelerated compared with conventionally reared animals. Mucosal induction of tolerance to allergen Bet v1 was not influenced by the presence or absence of microbiota. Identification of components of the microbiota and elucidation of the molecular mechanisms of their action in inducing pathological changes or exerting beneficial, disease-protective activities could aid in our ability to influence the composition of the microbiota and to find bacterial strains and components (e.g., probiotics and prebiotics) whose administration may aid in disease prevention and treatment.
    Full-text · Article · Jan 2011 · Cellular & molecular immunology
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    ABSTRACT: Commensal bacteria have been shown to modulate the host mucosal immune system. Here, we report that oral treatment of BALB/c mice with components from the commensal, Parabacteroides distasonis, significantly reduces the severity of intestinal inflammation in murine models of acute and chronic colitis induced by dextran sulphate sodium (DSS). The membranous fraction of P. distasonis (mPd) prevented DSS-induced increases in several proinflammatory cytokines, increased mPd-specific serum antibodies and stabilized the intestinal microbial ecology. The anti-colitic effect of oral mPd was not observed in severe combined immunodeficient mice and probably involved induction of specific antibody responses and stabilization of the intestinal microbiota. Our results suggest that specific bacterial components derived from the commensal bacterium, P. distasonis, may be useful in the development of new therapeutic strategies for chronic inflammatory disorders such as inflammatory bowel disease.
    Full-text · Article · Nov 2010 · Clinical & Experimental Immunology

Publication Stats

2k Citations
195.19 Total Impact Points

Institutions

  • 1984-2015
    • Academy of Sciences of the Czech Republic
      • • Institute of Hydrobiology
      • • Laboratory of Tumor Immunology
      • • Division of Immunology and Gnotobiology
      • • Laboratory of Natural Immunity
      Praha, Praha, Czech Republic
  • 2005-2013
    • University of Alabama at Birmingham
      • Department of Microbiology
      Birmingham, Alabama, United States
    • Charles University in Prague
      • Institute of Microbiology (Pilsen)
      Praha, Praha, Czech Republic
  • 1985-2008
    • The Police Academy of the Czech Republic in Prague
      Praha, Praha, Czech Republic
  • 1986
    • Food Research Institute Prague
      Praha, Praha, Czech Republic
  • 1972-1985
    • Institute for Clinical and Experimental Medicine (IKEM)
      Praha, Praha, Czech Republic
  • 1970
    • Centrum kardiovaskulární a transplantační chirurgie
      Brünn, South Moravian, Czech Republic