The CNS microenvironment promotes leukemia cell survival by disrupting tumor suppression and cell cycle regulation in pediatric T-cell acute lymphoblastic leukemia

A major obstacle in improving survival in pediatric T-cell acute lymphoblastic leukemia is understanding how to predict and treat leukemia relapse in the CNS. Leukemia cells are capable of infiltrating and residing within the CNS, primarily the leptomeninges, where they interact with the microenvironment and remain sheltered from systemic treatment. These cells can survive in the CNS, by hijacking the microenvironment and disrupting normal functions, thus promoting malignant transformation. While the protective effects of the bone marrow niche have been widely studied, the mechanisms behind leukemia infiltration into the CNS and the role of the CNS niche in leukemia cell survival remain unknown. We identified a dysregulated gene expression profile in CNS infiltrated T-ALL and CNS relapse, promoting cell survival, chemoresistance, and disease progression. Furthermore, we discovered that interactions between leukemia cells and human meningeal cells induced epigenetic alterations, such as changes in histone modifications, including H3K36me3 levels. These findings are a step towards understanding the molecular mechanisms promoting leukemia cell survival in the CNS microenvironment. Our results highlight genetic and epigenetic alterations induced by interactions between leukemia cells and the CNS niche, which could potentially be utilized as biomarkers to predict CNS infiltration and CNS relapse.

Malignant A-to-I RNA editing by ADAR1 drives T cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing

Leukemia-initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches. Here, we show that the RNA-editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine editing is a common attribute of relapsed T cell acute lymphoblastic leukemia (T-ALL) regardless of molecular subtype. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL patient-derived xenograft models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA to avoid detection by the innate immune sensor melanoma differentiation-associated protein 5 (MDA5). Moreover, we uncover that the cell-intrinsic level of MDA5 dictates the dependency on the ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents an effective therapeutic strategy for eliminating T-ALL LICs.

Malignant A-to-I RNA editing by ADAR1 drives T-cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing

Leukemia initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches to eliminate LICs and prevent relapse. Here, we show that the RNA editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine (A-to-I) editing is a common attribute of relapsed T-ALL regardless of molecular subtypes. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL PDX models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA and retains unedited nuclear dsRNA to avoid detection by the innate immune sensor MDA5. Moreover, we uncovered that the cell intrinsic level of MDA5 dictates the dependency on ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents a safe and effective therapeutic strategy for eliminating T-ALL LICs.

Malignant DFFB isoform switching promotes leukemia survival in relapse pediatric T-cell acute lymphoblastic leukemia

With modern treatment most children with acute lymphoblastic leukemia (ALL) survive without relapse. However, for children who relapse the prognosis is still poor, especially in children with T-cell phenotype (T-ALL) and remains the major cause of death. The exact mechanism of relapse is currently not known. While contribution of RNA processing alteration has been linked to other hematological malignancies, its contribution in pediatric T-ALL may provide new insights. Almost all human genes express more than one alternative splice isoform. Thus, gene modulation producing a diverse repertoire of the transcriptome and proteome have become a significant molecular marker of cancer and a potential therapeutic vulnerability. To study this, we performed RNA-sequencing analysis on patient-derived samples followed by splice isoform-specific PCR. We uncovered a distinct RNA splice isoform expression pattern characteristic for relapse samples compared to the leukemia samples from the time of diagnosis. We also identified deregulated splicing and apoptosis pathways specific for relapse T-ALL. Moreover, patients with T-ALL displayed pro-survival splice isoform switching favoring pro-survival isoforms compared to normal healthy stem cells. Cumulatively, pro-survival isoform switching and DFFB isoform regulation of SOX2 and MYCN may play a role in T-ALL proliferation and survival, thus serving as a potential therapeutic option.

Inflammation-driven deaminase deregulation fuels human pre-leukemia stem cell evolution

Inflammation-dependent base deaminases promote therapeutic resistance in many malignancies. However, their roles in human pre-leukemia stem cell (pre-LSC) evolution to acute myeloid leukemia stem cells (LSCs) had not been elucidated. Comparative whole-genome and whole-transcriptome sequencing analyses of FACS-purified pre-LSCs from myeloproliferative neoplasm (MPN) patients reveal APOBEC3C upregulation, an increased C-to-T mutational burden, and hematopoietic stem and progenitor cell (HSPC) proliferation during progression, which can be recapitulated by lentiviral APOBEC3C overexpression. In pre-LSCs, inflammatory splice isoform overexpression coincides with APOBEC3C upregulation and ADAR1p150-induced A-to-I RNA hyper-editing. Pre-LSC evolution to LSCs is marked by STAT3 editing, STAT3β isoform switching, elevated phospho-STAT3, and increased ADAR1p150 expression, which can be prevented by JAK2/STAT3 inhibition with ruxolitinib or fedratinib or lentiviral ADAR1 shRNA knockdown. Conversely, lentiviral ADAR1p150 expression enhances pre-LSC replating and STAT3 splice isoform switching. Thus, pre-LSC evolution to LSCs is fueled by primate-specific APOBEC3C-induced pre-LSC proliferation and ADAR1-mediated splicing deregulation.

Abstract 5726: A-to-I RNA deaminase deregulation in pre-leukemia stem cell evolution

While inflammation induced ADAR1 RNA deaminases protect the human genome from retroviral integration, deregulation promotes therapeutic resistance in many malignancies. However, the combinatorial role of these deaminases in pre-leukemia stem cell (pre-LSC) evolution to therapy resistant LSC had not been elucidated. Thus, we performed whole genome sequencing (WGS) analysis of 43 CD34+pre-leukemic myeloproliferative neoplasm (MPN) samples compared with matched saliva and non-MPN controls andwhole transcriptome sequencing (RNA-seq) analysis of 113 FACS-purified hematopoietic stem cells (HSC) and hematopoietic progenitor cells (HPC) from MPN, acute myeloid leukemia (AML) and healthy young and aged samples. During MPN progression, inflammation-driven ADAR1 isoform p150 upregulation corresponded with increased Adenosine-to-Inosine (A-to-I) transitions in both MPN stem and progenitor populations. We identified unique A-to-I editing events in coding regions that are associated with either normal stem progenitors or with MPN progenitors. In addition, STAT3 transcript hyper-editing leads to STAT3beta splice isoform expression. Moreover, lentiviral ADAR1p150 overexpression enhanced replating as well as beta-catenin activation, which was reversed by lentiviral shRNA ADAR1 knockdown. In summary, innate immune deaminase deregulation fuels pre-LSC evolution to LSC and may represent a vital LSC therapeutic vulnerability.

Citation Format: Qingfei Jiang, Frida Holm, Jane Isquith, Adam Mark, Cayla Mason, Eduardo Reynoso, Isabella Morris, Wenxue Ma, Raymond Diep, Jessica Pham, Chanond Nasamran, Guorong Xu, Roman Sasik, Sara Brin Rosenthal, Amanda Birmingham, Leslie Crews, Gabriel Pineda, Thomas Whisenant, Kathleen Fisch, Catriona Jamieson. A-to-I RNA deaminase deregulation in pre-leukemia stem cell evolution [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5726.

Abstract 3675: Elucidating the role and function of APOBEC3 DNA deaminases in myeloproliferative neoplasms

The prevalence of upregulated apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3 (APOBEC3) transcripts as well as a distinct mutational signature has been identified and presented extensively in numerous cancer types. Previously, this family of cytidine deaminases has been studied in innate immunity, as they are active in the conversion of cytosine to uracil to restrict retroviral replication. Recent studies employing whole exome sequencing of multiple cancer types have shown a significant increase in both APOBEC3 transcript level as well as an increase in mutations indicated as a result of APOBEC3 driven mutagenesis. However, the expression and role of these enzymes in cancer initiation and progression as well as the mechanisms by which the APOBEC3 enzymes elicit a response in the cancer microenvironment remains unknown, especially in hematopoietic malignancies. Here, we elucidate the APOBEC3 mutation phenotype in Myeloproliferative Neoplasms (MPNs) as well as the naïve cell populations of CD34+ cord blood and normal aged samples. Through RNA sequencing we have found a cell type and context specific nature of these enzymes, notably the upregulation of APOBEC3G (A3G) in the Myelofibrosis (MF) stem and progenitor cell population as compared to normal aged counterparts. There is also significant differential expression of APOBEC3C (A3C), APOBEC3D (A3D), and APOBEC3F (A3F) in MF disease states compared to normal controls. By cloning the APOBEC3 enzymes into lentiviral expression vectors, we can now study the physiological effects of changes in APOBEC3 transcript level in relation to the known changes in expression seen in many cancers, focusing on the upregulation of A3G through lentiviral overexpression. Using these techniques, we will also elucidate the mutation signature of APOBEC3G in CD34+ cord blood as compared to the known mutagenesis pattern derived from the editing signature of APOBEC3B. Upon APOBEC3G overexpression we can connect the prevalence and proposed activity of the enzymes to the physiological deregulation present in hematopoietic malignancies. We have found that A3G induces a proliferative burst in normal CD34+ cord blood, which leads us to study the effects of APOBEC3 upregulation in regards to proliferation, differentiation and self-renewal in normal and malignant cells as well as their potential function in disease initiation and progression in MPNs.

Citation Format: Jane Isquith, Qingfei Jiang, Raymond Diep, Jessica Pham, Frida Holm, Catriona Jamieson. Elucidating the role and function of APOBEC3 DNA deaminases in myeloproliferative neoplasms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3675.

Hyper-Editing of Cell-Cycle Regulatory and Tumor Suppressor RNA Promotes Malignant Progenitor Propagation

Adenosine deaminase associated with RNA1 (ADAR1) deregulation contributes to therapeutic resistance in many malignancies. Here we show that ADAR1-induced hyper-editing in normal human hematopoietic progenitors impairs miR-26a maturation, which represses CDKN1A expression indirectly via EZH2, thereby accelerating cell-cycle transit. However, in blast crisis chronic myeloid leukemia progenitors, loss of EZH2 expression and increased CDKN1A oppose cell-cycle transit. Moreover, A-to-I editing of both the MDM2 regulatory microRNA and its binding site within the 3' UTR region stabilizes MDM2 transcripts, thereby enhancing blast crisis progenitor propagation. These data reveal a dual mechanism governing malignant transformation of progenitors that is predicated on hyper-editing of cell-cycle-regulatory miRNAs and the 3' UTR binding site of tumor suppressor miRNAs.

RNA editing-dependent epitranscriptome diversity in cancer stem cells

Cancer stem cells (CSCs) can regenerate all facets of a tumour as a result of their stem cell-like capacity to self-renew, survive and become dormant in protective microenvironments. CSCs evolve during tumour progression in a manner that conforms to Charles Darwin's principle of natural selection. Although somatic DNA mutations and epigenetic alterations promote evolution, post-transcriptional RNA modifications together with RNA binding protein activity (the 'epitranscriptome') might also contribute to clonal evolution through dynamic determination of RNA function and gene expression diversity in response to environmental stimuli. Deregulation of these epitranscriptomic events contributes to CSC generation and maintenance, which governs cancer progression and drug resistance. In this Review, we discuss the role of malignant RNA processing in CSC generation and maintenance, including mechanisms of RNA methylation, RNA editing and RNA splicing, and the functional consequences of their aberrant regulation in human malignancies. Finally, we highlight the potential of these events as novel CSC biomarkers as well as therapeutic targets.

Selective microRNA-Offset RNA expression in human embryonic stem cells

Small RNA molecules, including microRNAs (miRNAs), play critical roles in regulating pluripotency, proliferation and differentiation of embryonic stem cells. miRNA-offset RNAs (moRNAs) are similar in length to miRNAs, align to miRNA precursor (pre-miRNA) loci and are therefore believed to derive from processing of the pre-miRNA hairpin sequence. Recent next generation sequencing (NGS) studies have reported the presence of moRNAs in human neurons and cancer cells and in several tissues in mouse, including pluripotent stem cells. In order to gain additional knowledge about human moRNAs and their putative development-related expression, we applied NGS of small RNAs in human embryonic stem cells (hESCs) and fibroblasts. We found that certain moRNA isoforms are notably expressed in hESCs from loci coding for stem cell-selective or cancer-related miRNA clusters. In contrast, we observed only sparse moRNAs in fibroblasts. Consistent with earlier findings, most of the observed moRNAs derived from conserved loci and their expression did not appear to correlate with the expression of the adjacent miRNAs. We provide here the first report of moRNAs in hESCs, and their expression profile in comparison to fibroblasts. Moreover, we expand the repertoire of hESC miRNAs. These findings provide an expansion on the known repertoire of small non-coding RNA contents in hESCs.

In vivo differentiated human embryonic stem cells can acquire chromosomal aberrations more frequently than in vitro during the same period

Human embryonic stem cells (hESCs) are regarded as a promising approach to generate transplantable cells for the treatment of several diseases. These cells offer an immense potential as a source of cells for regenerative medicine, but the possible ability of these cells to produce tumors in vivo presents a major impediment for the achievement of this potential in clinical reality. hESCs can obtain growth advantages in vitro by acquired mutations, a phenomenon called culture adaptation. The most common chromosome modifications involve chromosomes 12, 17, and X. The mechanisms that may influence chromosome modification in hESCs are not well known. We have performed a comparative in vitro and in vivo study on 3 hESC lines produced in our laboratory to see if there are changes also during in vivo growth. In vivo differentiated cells and in vitro cultured hESCs were analyzed by using a high-resolution Affymetrix SNP 6.0 array revealing DNA copy number variations. We were able, for the first time, to identify chromosomal aberrations that had occurred in vivo in one out of the 3 hESC lines. In the hESC line HS364 differentiated in vivo, an amplification of the whole X chromosome was detected, possibly due to mosaicism of XY and XX cells. In the hESC line HS366, array results showed small amplifications and gains. The third hESC line (HS368) was less altered, but contained also a new gain verified by fluorescent in situ hybridization in a teratoma in 21% of the cells. These results indicate that mutations occur during the in vivo differentiation process as well as in vitro. The potential of precancerous mutations in in-vivo conditions is important to consider for safety measures, and underlines the necessity to remove all pluripotent stem cells from the differentiated cell population that will be transplanted.

Improved cryopreservation of human hepatocytes using a new xeno free cryoprotectant solution

AIM

To optimize a xeno-free cryopreservation protocol for primary human hepatocytes.

METHODS

The demand for cryopreserved hepatocytes is increasing for both clinical and research purposes. Despite several hepatocyte cryopreservation protocols being available, improvements are urgently needed. We first compared controlled rate freezing to polystyrene box freezing and did not find any significant change between the groups. Using the polystyrene box freezing, we compared two xeno-free freezing solutions for freezing of primary human hepatocytes: a new medium (STEM-CELLBANKER, CB), which contains dimethylsulphoxide (DMSO) and anhydrous dextrose, both permeating and non-permeating cryoprotectants, and the frequently used DMSO - University of Wisconsin (DMSO-UW) medium. The viability of the hepatocytes was assessed by the trypan blue exclusion method as well as a calcein-esterase based live-dead assay before and after cryopreservation. The function of the hepatocytes was evaluated before and after cryopreservation by assessing enzymatic activity of 6 major cytochrome P450 isoforms (CYPs): CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4 and CYP3A7.

RESULTS

The new cryoprotectant combination preserved hepatocyte viability significantly better than the standard DMSO-UW protocol (P < 0.01). There was no significant difference in viability estimation between both the trypan blue (TB) and the Live-Dead Assay methods. There was a correlation between viability of fresh hepatocytes and the difference in cell viability between CB and DMSO protocols (r(2) = 0.69) using the TB method. However, due to high within-group variability in the activities of the major CYPs, any statistical between-group differences were precluded. Cryopreservation of human hepatocytes using the cryoprotectant combination was a simple and xeno-free procedure yielding better hepatocyte viability. Thus, it may be a better alternative to the standard DMSO-UW protocol. Estimating CYP activities did not seem to be a relevant way to compare hepatocyte function between different groups due to high normal variability between different liver samples.

CONCLUSION

The cryoprotectant combination may be a better alternative to the standard DMSO-UW protocol in primary human hepatocyte cryopreservation.

Looking beyond borders: integrating best practices in benefit-risk analysis into the field of food and nutrition

An integrated benefit-risk analysis aims to give guidance in decision situations where benefits do not clearly prevail over risks, and explicit weighing of benefits and risks is thus indicated. The BEPRARIBEAN project aims to advance benefit-risk analysis in the area of food and nutrition by learning from other fields. This paper constitutes the final stage of the project, in which commonalities and differences in benefit-risk analysis are identified between the Food and Nutrition field and other fields, namely Medicines, Food Microbiology, Environmental Health, Economics and Marketing-Finance, and Consumer Perception. From this, ways forward are characterized for benefit-risk analysis in Food and Nutrition. Integrated benefit-risk analysis in Food and Nutrition may advance in the following ways: Increased engagement and communication between assessors, managers, and stakeholders; more pragmatic problem-oriented framing of assessment; accepting some risk; pre- and post-market analysis; explicit communication of the assessment purpose, input and output; more human (dose-response) data and more efficient use of human data; segmenting populations based on physiology; explicit consideration of value judgments in assessment; integration of multiple benefits and risks from multiple domains; explicit recognition of the impact of consumer beliefs, opinions, views, perceptions, and attitudes on behaviour; and segmenting populations based on behaviour; the opportunities proposed here do not provide ultimate solutions; rather, they define a collection of issues to be taken account of in developing methods, tools, practices and policies, as well as refining the regulatory context, for benefit-risk analysis in Food and Nutrition and other fields. Thus, these opportunities will now need to be explored further and incorporated into benefit-risk practice and policy. If accepted, incorporation of these opportunities will also involve a paradigm shift in Food and Nutrition benefit-risk analysis towards conceiving the analysis as a process of creating shared knowledge among all stakeholders.

Screening ethnically diverse human embryonic stem cells identifies a chromosome 20 minimal amplicon conferring growth advantage

The International Stem Cell Initiative analyzed 125 human embryonic stem (ES) cell lines and 11 induced pluripotent stem (iPS) cell lines, from 38 laboratories worldwide, for genetic changes occurring during culture. Most lines were analyzed at an early and late passage. Single-nucleotide polymorphism (SNP) analysis revealed that they included representatives of most major ethnic groups. Most lines remained karyotypically normal, but there was a progressive tendency to acquire changes on prolonged culture, commonly affecting chromosomes 1, 12, 17 and 20. DNA methylation patterns changed haphazardly with no link to time in culture. Structural variants, determined from the SNP arrays, also appeared sporadically. No common variants related to culture were observed on chromosomes 1, 12 and 17, but a minimal amplicon in chromosome 20q11.21, including three genes expressed in human ES cells, ID1, BCL2L1 and HM13, occurred in >20% of the lines. Of these genes, BCL2L1 is a strong candidate for driving culture adaptation of ES cells.

State of the art in benefit-risk analysis: food and nutrition

Benefit-risk assessment in food and nutrition is relatively new. It weighs the beneficial and adverse effects that a food (component) may have, in order to facilitate more informed management decisions regarding public health issues. It is rooted in the recognition that good food and nutrition can improve health and that some risk may be acceptable if benefit is expected to outweigh it. This paper presents an overview of current concepts and practices in benefit-risk analysis for food and nutrition. It aims to facilitate scientists and policy makers in performing, interpreting and evaluating benefit-risk assessments. Historically, the assessments of risks and benefits have been separate processes. Risk assessment is mainly addressed by toxicology, as demanded by regulation. It traditionally assumes that a maximum safe dose can be determined from experimental studies (usually in animals) and that applying appropriate uncertainty factors then defines the 'safe' intake for human populations. There is a minor role for other research traditions in risk assessment, such as epidemiology, which quantifies associations between determinants and health effects in humans. These effects can be both adverse and beneficial. Benefit assessment is newly developing in regulatory terms, but has been the subject of research for a long time within nutrition and epidemiology. The exact scope is yet to be defined. Reductions in risk can be termed benefits, but also states rising above 'the average health' are explored as benefits. In nutrition, current interest is in 'optimal' intake; from a population perspective, but also from a more individualised perspective. In current approaches to combine benefit and risk assessment, benefit assessment mirrors the traditional risk assessment paradigm of hazard identification, hazard characterization, exposure assessment and risk characterization. Benefit-risk comparison can be qualitative and quantitative. In a quantitative comparison, benefits and risks are expressed in a common currency, for which the input may be deterministic or (increasingly more) probabilistic. A tiered approach is advocated, as this allows for transparency, an early stop in the analysis and interim interaction with the decision-maker. A general problem in the disciplines underlying benefit-risk assessment is that good dose-response data, i.e. at relevant intake levels and suitable for the target population, are scarce. It is concluded that, provided it is clearly explained, benefit-risk assessment is a valuable approach to systematically show current knowledge and its gaps and to transparently provide the best possible science-based answer to complicated questions with a large potential impact on public health.

State of the art in benefit-risk analysis: introduction

Risk-taking is normal in everyday life if there are associated (perceived) benefits. Benefit-Risk Analysis (BRA) compares the risk of a situation to its related benefits and addresses the acceptability of the risk. Over the past years BRA in relation to food and food ingredients has gained attention. Food, and even the same food ingredient, may confer both beneficial and adverse effects. Measures directed at food safety may lead to suboptimal or insufficient levels of ingredients from a benefit perspective. In BRA, benefits and risks of food (ingredients) are assessed in one go and may conditionally be expressed into one currency. This allows the comparison of adverse and beneficial effects to be qualitative and quantitative. A BRA should help policy-makers to make more informed and balanced benefit-risk management decisions. Not allowing food benefits to occur in order to guarantee food safety is a risk management decision much the same as accepting some risk in order to achieve more benefits. BRA in food and nutrition is making progress, but difficulties remain. The field may benefit from looking across its borders to learn from other research areas. The BEPRARIBEAN project (Best Practices for Risk-Benefit Analysis: experience from out of food into food; http://en.opasnet.org/w/Bepraribean) aims to do so, by working together with Medicines, Food Microbiology, Environmental Health, Economics & Marketing-Finance and Consumer Perception. All perspectives are reviewed and subsequently integrated to identify opportunities for further development of BRA for food and food ingredients. Interesting issues that emerge are the varying degrees of risk that are deemed acceptable within the areas and the trend towards more open and participatory BRA processes. A set of 6 'state of the art' papers covering the above areas and a paper integrating the separate (re)views are published in this volume.

State of the art in benefit-risk analysis: food microbiology

Over the past years benefit-risk analysis (BRA) in relation to foods and food ingredients has gained much attention; in Europe and worldwide. BRA relating to food microbiology is however a relatively new field of research. Microbiological risk assessment is well defined but assessment of microbial benefits and the weighing of benefits and risk has not been systematically addressed. In this paper the state of the art in benefit-risk analysis in food microbiology is presented, with a brief overview of microbiological food safety practices. The quality and safety of foods is commonly best preserved by delaying the growth of spoilage bacteria and contamination by bacterial pathogens. However, microorganisms in food can be both harmful and beneficial. Many microorganisms are integral to various food production processes e.g. the production of beer, wine and various dairy products. Moreover, the use of some microorganisms in the production of fermented foods are often claimed to have beneficial effects on food nutrition and consumer health. Furthermore, food safety interventions leading to reduced public exposure to foodborne pathogens can be regarded as benefits. The BRA approach integrates an independent assessment of both risks and benefits and weighs the two using a common currency. Recently, a number of initiatives have been launched in the field of food and nutrition to address the formulation of the benefit-risk assessment approach. BRA has recently been advocated by EFSA for the public health management of food and food ingredients; as beneficial and adverse chemicals can often be found within the same foods and even the same ingredients. These recent developments in the scoping of BRA could be very relevant for food microbiological issues. BRA could become a valuable methodology to support evaluations and decision making regarding microbiological food safety and public health, supplementing other presently available policy making and administrative tools for microbiological food safety management.

No relationship between embryo morphology and successful derivation of human embryonic stem cell lines

Background

The large number (30) of permanent human embryonic stem cell (hESC) lines and additional 29 which did not continue growing, in our laboratory at Karolinska Institutet have given us a possibility to analyse the relationship between embryo morphology and the success of derivation of hESC lines. The derivation method has been improved during the period 2002–2009, towards fewer xeno-components. Embryo quality is important as regards the likelihood of pregnancy, but there is little information regarding likelihood of stem cell derivation.

Methods

We evaluated the relationship of pronuclear zygote stage, the score based on embryo morphology and developmental rate at cleavage state, and the morphology of the blastocyst at the time of donation to stem cell research, to see how they correlated to successful establishment of new hESC lines.

Results

Derivation of hESC lines succeeded from poor quality and good quality embryos in the same extent. In several blastocysts, no real inner cell mass (ICM) was seen, but permanent well growing hESC lines could be established. One tripronuclear (3PN) zygote, which developed to blastocyst stage, gave origin to a karyotypically normal hESC line.

Conclusion

Even very poor quality embryos with few cells in the ICM can give origin to hESC lines.

A teratocarcinoma-like human embryonic stem cell (hESC) line and four hESC lines reveal potentially oncogenic genomic changes

The first Swiss human embryonic stem cell (hESC) line, CH-ES1, has shown features of a malignant cell line. It originated from the only single blastomere that survived cryopreservation of an embryo, and it more closely resembles teratocarcinoma lines than other hESC lines with respect to its abnormal karyotype and its formation of invasive tumors when injected into SCID mice. The aim of this study was to characterize the molecular basis of the oncogenicity of CH-ES1 cells, we looked for abnormal chromosomal copy number (by array Comparative Genomic Hybridization, aCGH) and single nucleotide polymorphisms (SNPs). To see how unique these changes were, we compared these results to data collected from the 2102Ep teratocarcinoma line and four hESC lines (H1, HS293, HS401 and SIVF-02) which displayed normal G-banding result. We identified genomic gains and losses in CH-ES1, including gains in areas containing several oncogenes. These features are similar to those observed in teratocarcinomas, and this explains the high malignancy. The CH-ES1 line was trisomic for chromosomes 1, 9, 12, 17, 19, 20 and X. Also the karyotypically (based on G-banding) normal hESC lines were also found to have several genomic changes that involved genes with known roles in cancer. The largest changes were found in the H1 line at passage number 56, when large 5 Mb duplications in chromosomes 1q32.2 and 22q12.2 were detected, but the losses and gains were seen already at passage 22. These changes found in the other lines highlight the importance of assessing the acquisition of genetic changes by hESCs before their use in regenerative medicine applications. They also point to the possibility that the acquisition of genetic changes by ESCs in culture may be used to explore certain aspects of the mechanisms regulating oncogenesis.

An effective serum- and xeno-free chemically defined freezing procedure for human embryonic and induced pluripotent stem cells

BACKGROUND

Both human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) bear a great potential in regenerative medicine. In addition to optimized clinical grade culture conditions, efficient clinical grade cryopreservation methods for these cells are needed. Obtaining good survival after thawing has been problematic.

METHODS

We used a novel, chemically defined effective xeno-free cryopreservation system for cryostorage and banking of hESCs and iPSCs. The earlier established slow freezing protocols have, even after recent improvements, resulted in low viability and thawed cells had a high tendency to differentiate. The medium is a completely serum and animal substance free product containing dimethylsulfoxide, anhydrous dextrose and a polymer as cryoprotectants. The cells were directly frozen at -70 degrees C, without a programmed freezer.

RESULTS

The number of frozen colonies versus the number of surviving colonies differed significantly for both HS293 (chi(2) = 9.616 with one degree of freedom and two-tailed P = 0.0019) and HS306 (chi(2) = 8.801 with one degree of freedom and two-tailed P = 0.0030). After thawing, the cells had a high viability (90-96%) without any impact on proliferation and differentiation, compared with the standard freezing procedure where viability was much lower (49%). The frozen-thawed hESCs and iPSCs had normal karyotype and maintained properties of pluripotent cells with corresponding morphological characteristics, and expressed pluripotency markers after 10 passages in culture. They formed teratomas containing tissue components of the three germ layers.

CONCLUSION

The defined freezing-thawing system described here offers an excellent simple option for banking of hESCs and iPSCs.

Derivation of 30 human embryonic stem cell lines--improving the quality

We have derived 30 human embryonic stem cell lines from supernumerary blastocysts in our laboratory. During the derivation process, we have studied new and safe method to establish good quality lines. All our human embryonic stem cell lines have been derived using human foreskin fibroblasts as feeder cells. The 26 more recent lines were derived in a medium containing serum replacement instead of fetal calf serum. Mechanical isolation of the inner cell mass using flexible metal needles was used in deriving the 10 latest lines. The lines are karyotypically normal, but culture adaptation in two lines has been observed. Our human embryonic stem cell lines are banked, and they are available for researchers.

Comparison of defined culture systems for feeder cell free propagation of human embryonic stem cells

There are many reports of defined culture systems for the propagation of human embryonic stem cells in the absence of feeder cell support, but no previous study has undertaken a multi-laboratory comparison of these diverse methodologies. In this study, five separate laboratories, each with experience in human embryonic stem cell culture, used a panel of ten embryonic stem cell lines (including WA09 as an index cell line common to all laboratories) to assess eight cell culture methods, with propagation in the presence of Knockout Serum Replacer, FGF-2, and mouse embryonic fibroblast feeder cell layers serving as a positive control. The cultures were assessed for up to ten passages for attachment, death, and differentiated morphology by phase contrast microscopy, for growth by serial cell counts, and for maintenance of stem cell surface marker expression by flow cytometry. Of the eight culture systems, only the control and those based on two commercial media, mTeSR1 and STEMPRO, supported maintenance of most cell lines for ten passages. Cultures grown in the remaining media failed before this point due to lack of attachment, cell death, or overt cell differentiation. Possible explanations for relative success of the commercial formulations in this study, and the lack of success with other formulations from academic groups compared to previously published results, include: the complex combination of growth factors present in the commercial preparations; improved development, manufacture, and quality control in the commercial products; differences in epigenetic adaptation to culture in vitro between different ES cell lines grown in different laboratories.

Les facteurs cliniques et opératoires associés à la mortalité hospitalière après chirurgie d’une sténose du tronc commun de l’artère coronaire gauche

Stenosis of left main coronary artery (LMCA) is a common finding on coronary angiographies (7 to 10%). Mortality is very high for conservative therapy in comparison with surgery, which provides very good long-term outcome and is accepted as the standard therapy of this condition. Over the last few years, percutaneous coronary intervention (PCI) has become a new alternative in selected patients.

AIM OF THE STUDY

To assess in hospital mortality in subjects referred to our surgical unit for coronary artery bypass grafting (CABG) and to identify the main clinical and surgical determinants of in-hospital mortality.

METHODS

Two year retrospective analysis (1998-1999) of in-hospital mortality and morbidity of patients having left main stenosis referred for CABG.

RESULTS

Among a group of 1443 patients operated for coronary heart disease, LMCA stenosis was found in 330 patients (22.9%). The mean age was 63 +/- 8.6 years. Elective surgery was done in 173 patients (52.4%), and acute operation (i.e. urgent, emergent or desperate) in 157 patients (47.6%). The total in-hospital mortality was 4.2% (14/330). Elective surgery in-hospital mortality was 1.7% (3/173) and urgent surgery in-hospital mortality was 7% (11/157). The main risk factors of in-hospital mortality were age > 68 years, low ejection fraction (LVEF<0.4), history of myocardial infarction, gender (female) and urgency of the operation.

CONCLUSION

The proportion of patients undergoing CABG for left main stenosis is relatively high in our center and their mortality is quite low especially for elective operations. As the mortality of patients treated by PCI for LMCA stenosis is similar to surgery in high-risk patients, we postulate that this approach can be a real alternative treatment for such patients. Because of its potential benefit, combined revascularisation is also an alternative that should be considered in some cases. Furthermore, as a new generation of coated stents has emerged in the treatment of restenosis after PCI, we hypothesize that this method can in the near future be accepted as equivalent to surgery. However several randomized clinical trials must first be conduced prove this point.

[Effect of primary coronary angioplasty on long-term prognosis in patients with diabetes mellitus]

OBJECTIVES

To investigate feasibility and safety of primary PCI in diabetic patients.

BACKGROUND

Diabetic patients with acute myocardial infarction (AMI) have been shown to be at high risk for adverse clinical outcomes. Limited data is available on long term prognosis of diabetics treated with primary PCI.

METHODS

Retrospective analysis of consecutive 67 diabetic patients and 211 non diabetic patients treated with primary PCI from 1/1995 to 12/1999, follow up for 38 +/- 12 months.

RESULTS

The baseline characteristics were comparable in both groups. The mean age was 62 years in diabetic patients and 59 years in non diabetic patients. Hypertension (50% vs. 36%, p = 0.05), contraindications to thrombolytic treatment (13.4% vs. 5.7%, p = 0.037), cardiogenic shock (16.4% vs. 7.1%, p = 0.023), multivessel disease (34% vs. 23%, p = 0.07) and longer time delay to treatment (240 vs. 180 min., p = 0.05) were more often present in diabetic group. 47% of diabetic and 42% of nondiabetic patients received stents. The TIMI 2 or 3 flow rates were reached in 91% of diabetic patients and in 90% of nondiabetic patients, but TIMI 2 flow was found more often in diabetics (9% vs. 2.4%, p = 0.016). Higher rate of bleeding complications leading to significant change in the blood count (7.5% vs. 1.4%, p = 0.01) and higher 30 day mortality (11.9% vs. 5.2%, p = 0.05) was observed in diabetic group. However when the shock patients were excluded from the analysis, the 30 day mortality was different insignificantly in both groups (4.5% vs. 2.4%, p = 0.36). During follow up of 259 acute phase survivors 24 patients died. There was a trend to higher total long term mortality (22.3% vs. 13.2%, p = 0.07) and higher rate of nonfatal reinfarction (13.4% vs. 6.2%, p = 0.05) in diabetic group.

CONCLUSIONS

Primary PCI is safe and effective treatment of diabetic patients presenting with AMI. The higher rate of slow flow in infarct related artery after PCI observed in diabetics can be one of reasons for higher 30 day mortality in this group. Mean ischemic time in diabetics is behind the 4 hour border, where the possible benefit from reperfusion decreases. The main reason for higher mortality in our diabetic group was the higher rate of cardiogenic shock. Higher risk of bleeding complications at puncture site in diabetic patients can be explained by the lower quality of vessel wall.

[Comparison of the morphology of atherosclerotic plaques in patients with stable angina pectoris and acute coronary syndrome using intravascular ultrasonography]

The article summarises present knowledge on the differences in the structure of atherosclerotic plaques in patients with stable angina pectoris and in those with acute coronary syndrome during intravascular ultrasound examination. Authors describe differences in the pathologic anatomy and also in the clinics. The review includes pictures of the typical structural features and references of papers with similar topics.

[Long-term prognosis in patients with acute myocardial infarct and treatment with direct coronary angioplasty]

BACKGROUND

Primary coronary angioplasty (PTCA) has a beneficial effect on the immediate prognosis for patients with acute myocardial infarction. Number of information about effects of direct PTCA on the long-term prognosis are less numerous. The aim of the work was to establish the long-term prognosis for not-selected patients treated by direct PTCA.

METHODS AND RESULTS

The studied group consisted of 279 patients with acute myocardial infarction treated by direct PTCA in years 1995 to 1999 for the period of 38 +/- 12 months. Part of them were out-door patients of our clinic. The necessary data of the other patients were obtained by a questionnaire and by a telephone contact. 45 (16%) patients were lost from the follow up. The mortality rate of the study group was compared with data in the central register of Czech Republic. Positive angiographic effect of the direct PTCA (residual stenosis < 50% + flow TIMI 3) was achieved in 90% of patients. 30-day mortality was 6.8%, after excluding patients with cardiogenic shock it decreased to 3.2%. 6 patients (2.2%) had non-fatal infarction within 30 days after the first attack. From 259 patients who survived the acute infarction phase 24 died during the next period of follow up, 18 (7%) patients had a relapse of non-fatal infarction. PTCA of the infarcted artery was done in 15% of patients, PTCA of another artery in 9% of patients. The aorthocoronary bypass was indicated in 6% of patients. Almost half of relapses occurred during the first year after the hospitalisation. The risk factors of the death during the follow up were the age > 70 years, ejection fraction < 35%, impairment of 3 or more coronary artery branches, i.m. in the history, duration of ischemia > 4 hours, and diabetes mellitus. The total mortality was 11.4% in the first year, 1.4% in the second and 3.3% in the third year of the follow up.

CONCLUSIONS

The beneficial prognostic effect of the direct PTCA on patients with acute infarction carries through the whole period of follow up. Prognosis of the risk patients remains critical. Next revascularization of the infarcted artery was in our cohort of patients necessary in 21% of patients.

[Pharmacologic therapy of acute coronary syndromes]

Acute coronary syndromes (ACS) are caused by neoinclusive thrombosis of the coronary artery. Arterial atherothrombosis usually results from a cracked atheroma plate and includes platelet and plasmatic component of coagulation. The aim of pharmacological treatment is to influence activated platelets and plasma procoagulant activity. Several clinical studies have demonstrated the benefits of antithrombotic treatment by acetylsalicylic acid, clopidogrel and by blockers of platelet receptors IIb/IIIa. In ACS anticoagulant therapy the non-fractionated heparin are replace ed by low-molecular heparins. The new standard in ACS therapy should become a combination of the acetylsalicylic acid, enoxaparine and clopidogrel. Blockers of platelet receptors IIb/IIIa should be given namely to patients indicated for the early invasive treatment.

[Long-term treatment with statins in patients with ischemic heart disease after coronary angioplasty]

Long-term statin therapy is the corner-stone in management of patients with coronary artery disease.

PURPOSE OF STUDY

The aim of our study was to analyze the state of the statin therapy at patients undergoing percutaneous coronary intervention (PCI) and to determine predictors of long-term statin treatment.

METHODS

We performed a retrospective study in 520 patients who underwent percutaneous coronary angioplasty in 2nd Dept. of Internal Medicine, 1st School of Medicine, Charles University, Prague during the year 2000. Data were collected from hospital records and from a mailed questionnaire.

RESULTS

The response rate was 61.9% and the average response time was 11.6 +/- 3.5 months after PCI. Long-term statin therapy was prescribed in 52.5%. In patients with hypercholesterolemia 67.1% were treated in comparison with 32.3% treated patients without this diagnosis (p < 0.0001). Patients aged 70 years and older were treated significantly less frequently then younger individuals (30.6% vs. 61.3%, p < 0.0001). Patients with a history of prior revascularization procedure were treated significantly more often then patients undergoing the first procedure (64.8% vs. 49.8%, p < 0.05). Multivariate logistic regression analysis was applied to detect significant predictors of long-term statin therapy. Only hypercholesterolemia and statin prescription at discharge were identified as independent positive predictors, whereas age > or = 70 years and male gender had negative predictive value.

CONCLUSION

By course of evidence-based medicine, patients who underwent PCI in our study are undertreated by statins. Statin treatment should be initiated in all patients treated by PCI with increased cardiovascular risk. Patients at defined risk for undertreatment are mainly older patients and men. The prescription of statin therapy at the time of hospital discharge appears to be a very effective tool to improve long-term statin therapy.

[Idiopathic aneurysm of the pulmonary artery]

Aneurysm of pulmonary artery (PAA) is relatively rare clinical finding and appears mostly in association with significant cardiovascular or pulmonary abnormalities and is frequently caused by pulmonary hypertension. Its diagnosis is not difficult. However, guidelines for the treatment were not yet established. Patients with PAA are at risk for sudden death by a rupture of aneurysm. Therefore, surgical correction (graft replacement) is the method of choice. Nevertheless, it seems that certain group of patients with asymptomatic idiopathic aneurysm of pulmonary artery without presence of any serious cardiovascular or pulmonary abnormality can profit from conservative approach. We refer a 62-years old man with idiopathic PAA, in whom we did not indicate surgical correction. However, the long-term follow-up is necessary.

[Comparison of the occurrence of positive and negative vascular remodeling in patients with stable vs unstable angina pectoris]

BACKGROUND

The vascular remodelling refers to the increase or decrease in EEM (external elastica membrane) area that occurs during development of atherosclerosis. The positive remodeling, which was thought only as a compensatory factor during atheroma development, was also found as a one of the main features of unstable plaque. The intravascular ultrasound is very good tool to measure different type of arterial remodelling. These findings correlate with histologic post-mortem specimen with excellent results.

AIM OF THE STUDY

To correlate the remodelling index from patients suffered from stable angina pectoris (SAP) and from patients suffered from unstable angina (UA).

METHOD

We performed IVUS in 51 patients. In the group of patients with unstable angina were included patients with worsening angina symptoms in last six weeks or with angina in rest. We used IVUS--endosonics In-Vision with 30 MHz probe Awanar with mechanical pull-back. We studied the occurrence of positive remodelling, negative remodeling (an index that describes remodeling is expressed as: lesion EEM CSA/reference EEM CSA. If the lesion EEM area is greater than the reference EEM area, positive remodelling has occurred, and the index will be > 1.0. If the lesion EEM area is smaller than the reference EEM area, negative remodelling has occurred, and the index will be < 1.0).

RESULTS

We performed the intravascular ultrasound in 51 patients, 22 patients (43.1%) with unstable angina (UA) and in 29 patients (56.9%) stable angina (SAP). The positive remodelling was found in 14 patients (63.6%) in UA group vs. 5 patients (17.2%) in group with SAP, p < 0.05. The negative remodelling was found in 6 patients (27.3%) in UA group vs. 23 patients (79.3%) in SAP group, p < 0.05.

CONCLUSION

Positive remodelling is more often found in patients with UA vs. in patients with SAP. Positive arterial remodelling is therefore one of the features of unstable atherosclerotic plaque.

[Effect of delaying reperfusion therapy with PTCA on long term prognosis in patients with acute myocardial infarct]

BACKGROUND

The benefit of thrombolysis in patients with acute myocardial infarction (AMI) strongly depends on the time from onset of symptoms to the initiation of treatment. For AMI patients treated with PTCA this time seems to be important only to a certain time level. The aim of this study was to assess the influence of time to treatment of AMI with coronary angioplasty on short term and long term prognosis.

METHODS

We followed 339 consecutive AMI patients treated with coronary angioplasty from 1995 to 1999 in a cardiac care unit. Patients were divided to five groups according to time to treatment.

RESULTS

Time to treatment < 90 min. was achieved in 35 (10.5%); 91-210 min. in 105 (31%); 211-330 min. in 72 (21%); 331-690 min. in 74; > 691 min. in 53 (15.5%) patients. Ischemic time (time from symptom onset to reperfusion) in the groups was < 2 h.; 2-4 h.; 4-6 h; 6-12 h; > 12 h. respectively. The ejection fraction of left ventricle 3-5 days after AMI was 50%, 51%, 45%, 40%, 46% and the 30 day mortality was 5.7%, 2.9%, 11.1%, 10.8%, 11.3% in the groups respectively, showing no significant differences between the groups. However the higher rate of TIMI 3 flow was achieved in patients with time to treatment shorter than 3.5 h. compared to patients treated later (93.6% vs. 83.9%, p = 0.007). The lower 30 day mortality (3.6% vs. 11.1%, p = 0.012), lower 3 year mortality (8.6% vs. 19.1%, p = 0.003), lover frequency of heart failure during hospitalisation (11.4% vs. 28.1%, p < 0.001) as well as lower maximal level of released kreatinkinase (32 +/- 29 vs. 44 +/- 39 mukat/l, p = 0.005) was observed in patients treated within 3.5 h. from symptoms onset compared to patients treated later.

CONCLUSION

The success rate of primary PTCA to achieve normal flow in infarct related artery is high, but decreases when treatment is started later than 3.5 h. from AMI onset. The short term and long term mortality as well as incidence of heart failure during acute phase is lowest when the intervention was started within 3.5 h. from symptoms onset. Initiation of intervention after 3.5 h. resulted in significant mortality increase, but further delay of treatment had minimal impact on patients prognosis. Great effort needs to be paid to start the primary PTCA within 3.5 h. from AMI onset in as many patients as possible. From our data we can indirectly conclude: patients without a chance for reperfusion with thrombolytic therapy within 4 h. from symptoms onset should be considered candidates for PTCA regardless the time of transportation. In patients with chance to reperfuse infarct related artery within 4 h. from symptoms onset with thrombolytic treatment (thrombolysis needs to be started before 2.5-3rd h.) while having low probability to start PTCA within 3.5 h., the thrombolysis should be given first and PTCA performed later if needed.

[Video-assisted myocardial revascularization and left-sided minithoracotomy using the Symmetry automatic connector]

OBJECTIVE

Introduction of the new method of videoassisted multiple direct revascularization of the heart muscle from left-sided minithoracotomy (LAST--Left Anterior Small Thoracotomy) using an automatic connector of central anastomoses Symmetry (St. Jude Medical ATG, Inc., St. Paul, MN) in patients indicated for re-operation of bypasses of the coronary arteries or with pathological conditions of the sternum and for the cosmetic effect of submammary incisions in women.

METHOD

From September 2001 to the end of February 2002 15 patients with affections of three arteries had an operation from a LAST approach with videoscopic construction of central anastomoses by means of a Symmetry connector with portal entries and the use of extracorporeal circulation introduced from the groin without cardioplegic arrest. Nine men and six women were operated with a mean age of 68.7 years and a mean ejection fraction (EF) of 58.2%. In seven instances reoperation of aortocoronary bypasses was involved; two patients with multiple myelomas (morbus Kahler) had a brittle and cavernously altered sternum, all six women wanted a small skin incision below the breast. The criterion for ruling out the mentioned procedure was marked atherosclerotic affection of the ascendent aorta, affection of the arteries in the aortoiliac area and affection of one or two coronary arteries suitable for miniinvasive revascularization without extracorporeal circulation. Fourteen patients had an angiographic check up examination of the patency of grafts before they were discharged.

RESULTS

The total number of distal anastomoses per patient was 3.13 +/- 0.6, the median period of extracorporeal circulation was 112 +/- 34 minutes and the mean time of operation 186 +/- 52 minutes. Blood losses were on average 425 ml/24 h without necessity of revision on account of haemorrhage. Eleven (73%) patients were subjected to an ultra fast track protocol with extubation on the operating table. The mean time spent in the postoperative department was 8.6 hours and the total hospitalization period 5.5 days. None of the operated patients died. Peroperative ischaemia of the heart muscle was not observed, in one instance the authors observed a newly developed atrial fibrillation. During an angiographic check-up the authors detected 6 (13.6%) stenoses and occlusions in 44 checked bridged vessels.

CONCLUSION

The alternative approach reduces the risk of cardiac injury during reoperation and the danger of impaired healing of the sternotomical wound in patients with pathological conditions of the sternum, with contamination of the surrounding tissue (e.g. in tracheostomy) or malignant disease. The cosmetic effect of the submammary incision, the small inguinal incision and endoscopic saphenous vein harvesting should be considered in elective direct revascularization of the heart muscle in women. Bridging of the coronary arteries with optical assistance from minithoracotomy and with an automatic connector of central anastomoses seems to be a safe alternative of standard sternotomy only with methodological but not anatomical or functional restriction.

[Direct percutaneous transluminal coronary angioplasty in patients with acute myocardial infarct treated at the Cardiac Center of the General Medical School Hospital in Prague: a 1-year retrospective study]

Direct percutaneous transluminal coronary angioplasty (d-PTCA) in patients with acute myocardial infarctions (AIM) has become an alternative of thrombolytic treatment. If the involved department has adequate experience the success rate of the procedure is high and the immediate and long-term results are better than those of thrombolysis. Moreover contrary to thrombolytic treatment successful percutaneous coronary intervention in AIM is more beneficial for patients also later than 6 hours after the development of infarction pain. In the Cardiocentre of the General Faculty Hospital (GFH) patients with AIM are constantly attended, i.e. those indicated for reperfusion therapy are treated solely by the d-PTCA method.

OBJECTIVE AND METHOD

Retrospective analysis of d-PTCA in AIM made during the annual period from Jan. 1 2000 to Dec. 31 2000. Into the observation study patients were included with clinical and/or ECG signs of AIM when the period from the onset of pain to the beginning of intervention did not exceed 12 hours. All patients were given before the procedures 500 mg of acetylsalicylic acid and 10,000 u. heparin. Cardiac catheterization was implemented by the percutaneous Seldinger technique via the a. femoralis l.dx., in exceptional cases from the left femoral artery. An approach via the a. radialis and/or a. brachialis was not used in any of the patients. From the investigation patients were excluded who had before the percutaneous coronary intervention (PCI) a thrombolytic preparation (so-called rescue-PTCA).

RESULTS

During the mentioned period in the Cardiocentre of the GFH a total of 673 PTCA were performed, incl. 127 (18.9%) d-PTCA in patients with AIM. In the mentioned group of 127 patients subjected to intervention were 87 (68.5%) men and 40 (31.5%) women. The mean age of the men was 59.1 +/- 12 years and the mean age of the women 68.2 +/- 12 years. As to the main risk factors of coronary atherosclerosis arterial hypertension was present in 48%, smoking in 42%, diabetes in 23% and hyperlipoproteinaemia in 31% of the treated patients. More than one third of the patients had a history of myocardial infarction (38%). The infarcted artery was the r. interventricularis anterior (LAD) in 51 (40.2%), the right coronary artery (RCA) in 54 (42.5%), the r. circumflex (LCX) in 16 (12.6%), the left main coronary artery in 2 (1.6%) and the bypass in 4 (3.1%). Multiple coronary affections were recorded in 80 (63%) patients, affections of one artery in 47 (37%). Primary procedural success (flow TIMI 3/2) was achieved in 121 patients (95.3%). Normal flow through the infarcted artery TIMI 3 was achieved in 118/127 (85.8%) patients. In 91 (71.7%) into the infarcted artery a coronary stent was implanted, during hospitalization no subacute stenosis of the stent developed. The mean period between the onset of infarction pain--injection was 4.4 +/- 2.3 hours. The mean period of the entire procedures was 48 +/- 14.5 minutes. As contrast material only non-ionic contrast substances were used (Iomeron 350) with a mean consumption of 150 ml per patient. The mean skiascopic time was 13.6 +/- 1.8 min. A total of 9 (7.1%) patients were treated with GP IIb/IIIa receptor blockers (abciximab). The total hospitalization mortality of the intervened group was 7.1% (9 patients). In a sub-group of 9 patients who at the onset of the procedure were in cardiogenic shock 3 (33%) died. The hospitalization mortality of the sub-group of patients with AIM without cardiogenic shock, treated with d-PTCA was 5.1% (6/118). During hospitalization the authors did not observe any intracranial haemorrhage.

DISCUSSION

The group of subjects with AIM subjected to catheterization who are treated by d-PTCA is relatively numerous in our department. According to a number of clinical studies successful d-PTCA in AIM gives better short-term and long-term results as compared with thrombolytic therapy. The primary success rate of d-PTCA was high and the hospital mortality was low and comparable with contemporary data in the literature.

CONCLUSION

Direct PTCA is effective treatment in patients with acute myocardial infarction. The authors results confirm the high procedural success rate and acceptable hospital mortality. These favourable results of an invasive approach to treatment of AIM must be compared in future with bolus thrombolytic treatment by new types of thrombolytic preparations in combination with anti-platelet treatment with blockers of platelet glycoprotein receptors IIb/IIIa with/or without subsequent percutaneous coronary intervention.

[Complications in administration of contrast media in the catheterization laboratory: a 5-year retrospective study]

Iodine contrast substances (CS) are used since the twenties of the 20th century. From the chemical aspect benzoic acid derivatives are involved which are classified according to their osmolality (high-low- and isoosmolar) tendency of ionization (ionic and non-ionic) and according to the molecular structure monomers and dimers). Side-effects are due to their osmotic, ionic and chemical action on tissues. They include a number of systemic and organ symptoms (cardiovascular, immunological, haemocoagulation, neurological and renal), from the clinical aspect divided into mild, medium severe and severe. The relatively high incidence of undesirable reactions when ionic high-molecular CS are used led to the-development of non-ionic preparations with a lower osmolality, the more extensive use of which is limited by economic factors. Moreover so far convincing clinical data are lacking that the higher incidence of undesirable reactions after the use of CS has a clinical impact.

OBJECTIVE

To summarize experience with administration of CS in the catheterization laboratory of the Cardiocentre of the General Faculty Hospital during diagnostic and intervention procedures within 5 years with regard to the occurrence of undesirable effects when comparing ionic and non-ionic CS.

METHOD

Retrospective analysis of a group of patients examined in the catheterization laboratory to whom a CS was administered during the period between Jan. 1 1995 and Dec. 31 1999.

RESULTS

In 1995-1999 (5 years) in the catheterization laboratory a total of 10,149 procedures where implemented where ionic (ioxitalam-Telebrix 350) and non-ionic (iopromide Ultravist 370, ioversol--Optiray 370 and iomeprol-Iomeron 350) contrast substances were administered. Ionic CS were administered in 4,668 (46%) and non-ionic CS in 5,481 (54%) instances. Undesirable effects were recorded in a total of 107 (1.1%) patients, incl. ventricular fibrillation in 76 (0.75%), cardiac arrest in 12 (0.12%) and in 19 (0.19%) there were other undesirable effects (weakness, nausea, hypotension, flush, urtica etc.). Ionic and non-ionic CS participated equally in complications: ionic CS in 53 (49.5%) cases and non-ionic CS in 54 (50.5%), whereby no difference was observed in the type of complications. No death in conjucntion with administration of CS was observed.

CONCLUSION

The use of contemporary contrast substances in the catheterization laboratory for diagnostic and intervention procedures on the heart is relatively safe with a minimal risk of development of serious complications. No difference was observed between the use of ionic and non-ionic CS.

[Humoral profile of patients with severe aortic stenosis]

BACKGROUND

While the effect of neurohormones is often studied in congestive heart failure, their role in aortic stenosis needs to be elucidated.

METHODS

54 consecutive patients with symptomatic aortic stenosis without overt heart failure were studied at the age of 64.4 +/- 9.3 yrs with echocardiography, x-ray and catheterization. Levels of circulating atrial natriuretic factor endothelin-1, catecholamines, plasma renin activity, immunoreactive insulin and C-peptide were assessed, related to hemodynamic data and compared to those in 23 healthy controls, aged 59.2 +/- 12.8 yrs.

RESULTS

Patients had significantly higher plasma levels of endothelin-1 (z-value 0.64 +/- 1.19, p = 0.019), atrial natriuretic factor (z-value 2.46 +/- 2.46, p < 0.001) and dopamine (z-value 0.91 +/- 2.33, p = 0.02). Levels of endothelin-1 and ANF positively correlated with mean (r = 0.631, p < 0.001) and wedged pulmonary artery pressures and with left atrial diameter index (r = 0.602, p < 0.001). Endothelin-1 levels correlated negatively with aortic valve area (r = -0.306, p = 0.041). No correlation was found between neurohumoral plasma concentrations and left ventricular mass index.

CONCLUSIONS

In patients with symptomatic aortic stenosis without overt heart failure, elevated plasmatic levels of endothelin-1, atrial natriuretic factor and dopamine were documented. The increase of ET-1 levels is related to pulmonary hypertension and severity of the disease. Left ventricular hypertrophy is not related to neurohormonal levels. Neither circulating system renin-angiotensin nor noradrenaline are activated in these patients.

[Effect of a revascularization procedure on functioning of the hibernating myocardium]

Persistent abnormalities of left ventricular wall motion in patients with chronic coronary artery disease can be reversed by successful coronary artery bypass surgery or coronary angioplasty. The identification of hibernating myocardium has therefore important therapeutic and prognostic implications. Echocardiography with low dose dobutamine infusion can detect viable myocardium in patients with chronic left ventricular dysfunction. We have studied 32 patients with angiographically confirmed coronary artery disease and left ventricular dysfunction. The effect of dobutamine infusion (5 micrograms/kg/min. followed by 10 micrograms/kg/min) on left ventricular function was evaluated before coronary revascularization (PTCA, n = 20); CABGm b = 12) and compared with early period after revascularization (1-7 days) and 6-7 months later. Before revascularization 226 segments were hypokinetic, akinetic or dyskinetic, improvement was observed in 122 segments during dobutamine echocardiography. Mean (+/- SD) segment score indexes were 2.50 +/- 0.17 at baseline, 2.04 +/- 0.19 (p < 0.001) after dobutamine infusion, 2.24 +/- 0.25 (p < 0.001) early after and 1.87 +/- 0.25 (p < 0.001) late after revascularization. Sensitivity of dobutamine infusion to predict improvement early and late after revascularization was 84% and 85% respectively, specificity was 85% and 90% respectively. Echocardiography during low dose dobutamine infusion is save and accurate method for identifying of hibernating myocardium and predicts early and late reversibility of wall motion in selected patients with coronary artery disease and chronic left ventricular dysfunction.

[Aneurysms of the left atrium and left atrial appendage]

BACKGROUND

The authors deal with the problem of rare congenital and acquired aneurysm of the left atrium and auricular appendage. The authors attempted to compare findings on operation with results of preoperative examinations and evaluate the yield of echocardiographic and angiocardiographic examinations.

METHODS AND RESULTS

The authors had the opportunity to encounter this unusual finding of cardiac aneurysms in five patients operated in 1987-1990 on account of an advanced mitral defect associated in two patients with ischaemic heart disease. In all patients acquired aneurysms were involved. In two a large thrombus was found.

CONCLUSIONS

In the diagnosis of aneurysms of the left atrium and auricular appendage transoesophageal echocardiography proved to be the most reliable method.

[Uncommon indications for coronary angioplasty]

During the period between March 16, 1989 and October 7, 1992 at the Second Medical Clinic of the First Medical Faculty, Charles University Prague a total of 173 coronary angioplasties were performed. With expanding experience and greater availability of controllable super thin conductors and balloon catheters with a small profile, gradually the indication criteria of coronary angioplasty were extended. In 93.1% of patients simple balloon dilatation of a significant stenosis of the coronary arteries was performed and in 6.9% before dilatation in addition an attempt of recanalization of a chronic occlusion of the coronary artery was made. In 74% of the patients one coronary stenosis was dilated, in 16.7% several stenoses, in 1.2% of the patients a covered stenosis of the trunk of the left coronary was dilated and in the same number an aortocoronary bypass was performed. Even in the group of patients where only one coronary stenosis was dilated the type B coronary affection according to the classification ACC/AHA predominated and the same applied to the entire group of patients.

[Indications for cornary angiography]

This is a summary of relative indications for the selection of patients for coronary angiography. Coronary angiography is an important part of clinical evaluation of patients with ischemic heart disease, valve heart disease, cardiomyopathies. Main groups of patients with ischemic heart disease are: angina pectoris after low levels of effort despite a good medical treatment, unstable angina, variant angina, angina with high risk of acute coronary syndromes from noninvasive exercise testing. In addition coronary angiography is indicated in patients with unexplained congestive heart failure, in patients with acute myocardial infarction with mechanical complication requiring cardiac surgery such as hemodynamically important mitral insufficiency, large ventricular septal defect or a large aneurysm leading to heart failure. Also in patients with sudden death syndrome unrelated to acute myocardial infarction. Patients with silent ischemia with known coronary artery disease and with known risk factors should undergo coronary angiography. Indication for coronary angiography is also in patients with hemodynamically important valvular, subvalvular or supravalvular heart disease in whom corrective surgery is contemplated.

A versatile method for integration of genes and gene fusions into the lambda attachment site of Escherichia coli

We have developed a versatile method for integration of modified genes and gene fusions into the bacteriophage lambda attachment site (attB) of the Escherichia coli chromosome. The method relies on two components: (1) a DNA integration cassette, flanked by multiple restriction enzyme sites, which contains the lambda attP site and, as a selectable marker, the Tn5 aphA gene conferring kanamycin resistance (KmR); and (2) a plasmid with the lambda int gene transcribed from the tet promoter. A fragment carrying the gene in question is ligated to the integration cassette, resulting in a circular piece of DNA unable to replicate. The ligation product is then transformed into a strain that contains the int-carrying plasmid. Selection for KmR results in colonies with the cassette integrated into the attB site of the E. coli chromosome. This method was used for integration of several lacZ and phoA promoter fusions. The integration products were analyzed by Southern hybridization. In addition, we found, fortuitously, that the ligated DNA circles could also integrate by homologous recombination, although usually at a much lower frequency than the Int-mediated integration into attB.

Cloning and characterization of the Escherichia coli phosphoglycerate kinase (pgk) gene

The pgk gene of Escherichia coli coding for the phosphoglycerate kinase was subcloned from the Carbon and Clarke collection plasmid pLC33-5. The position and direction of transcription of the pgk gene was determined by Tn5 insertion mutagenesis. Analysis of proteins encoded from these plasmids showed that the pgk gene product is a 40-kDa protein, and that the gene is transcribed from two promoters, one immediately in front of the gene and one in front of an upstream gene coding for a 38-kDa polypeptide of unknown function. The position of the Pgk protein on two-dimensional O'Farrel gels was identified, and from this we conclude that it is one of the proteins induced by anaerobiosis [Smith and Neidhardt, J. Bacteriol. 154 (1987) 336-343]. The pgk gene was also found to show growth phase regulation; the synthesis of Pgk protein was induced more than ten-fold during transition from the exponential to the stationary growth phase.

[Surgical treatment of postinfarction heart aneurysms and akinesias]

The paper deals with the problem of surgical treatment of cardiac aneurysms and akinesias from the aspect of indication of surgical tactics and technique, risk factors and achieved results. The group of 117 patients is divided into 74 patients operated in 1970-1982 and 43 patients operated in 1983-1987 when already medium hyperthermia was used permanently, similarly as cold cardioplegia, complete haemodilution, pulsed extracorporeal circulation and relieving drainage of the left ventricle via the pulmonary artery. The reduction of early mortality from 24.3% to 4.7% provides clear evidence of the advantages of this procedure. The authors draw attention to differences in indications of surgical treatment between classical aneurysms and akinesians and to the importance of revascularization operations performed nowadays, using aortocoronary bypasses.