Proteomic analysis of imatinib-resistant CML-T1 cells reveals calcium homeostasis as a potential therapeutic target.

Chronic myeloid leukemia (CML) therapy has markedly improved patient prognosis after introduction of imatinib mesylate for clinical use. However, a subset of patients develops resistance to imatinib and other tyrosine kinase inhibitors (TKIs), mainly due to point mutations in the region encoding the kinase domain of the fused BCR-ABL oncogene. To identify potential therapeutic targets in imatinib­resistant CML cells, we derived imatinib-resistant CML-T1 human cell line clone (CML-T1/IR) by prolonged exposure to imatinib in growth media. Mutational analysis revealed that the Y235H mutation in BCR-ABL is probably the main cause of CML-T1/IR resistance to imatinib. To identify alternative therapeutic targets for selective elimination of imatinib-resistant cells, we compared the proteome profiles of CML-T1 and CML-T1/IR cells using 2-DE-MS. We identified eight differentially expressed proteins, with strongly upregulated Na+/H+ exchanger regulatory factor 1 (NHERF1) in the resistant cells, suggesting that this protein may influence cytosolic pH, Ca2+ concentration or signaling pathways such as Wnt in CML-T1/IR cells. We tested several compounds including drugs in clinical use that interfere with the aforementioned processes and tested their relative toxicity to CML-T1 and CML-T1/IR cells. Calcium channel blockers, calcium signaling antagonists and modulators of calcium homeostasis, namely thapsigargin, ionomycin, verapamil, carboxyamidotriazole and immunosuppressive drugs cyclosporine A and tacrolimus (FK-506) were selectively toxic to CML-T1/IR cells. The putative cellular targets of these compounds in CML-T1/IR cells are postulated in this study. We propose that Ca2+ homeostasis can be a potential therapeutic target in CML cells resistant to TKIs. We demonstrate that a proteomic approach may be used to characterize a TKI-resistant population of CML cells enabling future individualized treatment options for patients.

[Outcomes of catheter ablation of atrial fibrillation in patients over 65 years of age]. / Výsledky katetrové ablace fibrilace síní u pacientu nad 65 let.

PURPOSE: This study assessed ablation techniques, recurrent arrhythmias, long-term outcomes, and complications of catheter ablation for atrial fibrillation (AF) in patients 65 years of age. METHODS: Consecutive patients aged < 65 years (n = 653) vs 65 years (n = 213), who underwent catheter ablation of AF in the course of eight years, were compared. Ablation strategy and procedure endpoints were left at the operators discretion. RESULTS: The group of patients 65 years comprised more females (p < 0.001), and more frequently presented with persistent AF (p = 0.010). These patients less frequently underwent simple pulmonary vein isolation (p = 0.017); on the contrary, extensive ablation including coronary sinus intervention was more common (p = 0.020). There was no difference in repeat ablation procedures (25 % vs 26 % patients; p = 0.823, or 1.4 vs 1.5 ablation procedures/1 patients; p = 0.479, respectively). Spectrum of recurrent arrhythmias did not differ between the groups except for more frequent paroxysmal AF before the first repeat ablation in patients < 65 years (p = 0.050). At the end of 49 ± 26 month total follow-up, stable sinus rhythm (SR) was achieved in 85 % patients < 65 years vs 76 % patients 65 years (p = 0.318). To maintain stable SR, older patients more often continued to take antiarrhythmic medication (p = 0.054). More serious complication occurred in 3.8 % of the patients 65 years vs 2.1 % of the patients < 65 years of age (p = 0.207). CONCLUSION: Patients 65 years of age achieved insignificantly worse long-term outcome after insignificantly fewer repeat ablation procedures, and with more frequent use of antiarrhythmic drugs. SR maintenance and risk of complications were, however, favorable.

[Acute myocardial infarction in young patients--severe failures in the system of acute and secondary care]. / Akutní infarkt myokardu u mladých nemocných - závazné nedostatky v systému akutní a následné péce.

INTRODUCTION: The incidence of cardiovascular (CV) diseases and acute myocardial infarction (AMI) in Czech Republic is de-clining. In spite of this in a proportion of patients AMI occurs in young age. The aim of our project was to assess the character of risk factors, precipitating diseases and the quality of care in young AMI survivors. METHODS: We included 132 patients (97 men and 35 women) in whom AIM with ST elevations occurred before age of 45 years in men and age of 50 years in women. Several results were compared to a control group composed of 84 healthy volunteers of comparable age. We assessed the course of the disease, extent of coronary involvement, subsequent therapy and control of risk factors after 3 years from the index event. RESULTS: Smoking represented the main risk factor - 85% patents were active smokers at the time of AMI and 9% were former smokers, 64% patients had a positive family history of CV disease. We found a higher prevalence of dyslipidemia history in men. In spite of high rate of statin use, laboratory examination during follow-up revealed higher triglyceride values and low levels of HDL-cholesterol in both genders. All together 23% of patients had a history of provoking underlying disease or precipitating factors (inflammatory diseases, malignancies, combined thrombophilias, drug abuse). In total 95% of patients underwent coronary angiography during the acute phase of AMI, the median time from pain onset to intervention was 9 hours. Most patients had single vessel disease, 14% had even coronary angiogram without clinically significant stenosis. The subsequent care was satisfactory concerning the rate of drug prescriptions. However, target lipid values were not reached in 78% patients and blood pressure targets in 37%. CONCLUSIONS: In patients who suffered AMI in young age, risk factors are dominated by smoking and positive family history of CV diseases. One fifth of patients suffer from other underlying disease (inflammatory disease, malignancies, combined thrombophilia) or have another precipitating factor (febrile disease, drug abuse). The acute care seems unsatisfactory due to late arrival of most patients to catheterization laboratories (underestimation of the disease, incorrect initial diagnosis). Subsequent therapy is well composed but lacks in intensity.

[S-100B protein elevation in patients with the acute coronary syndrome after resuscitation is a predictor of adverse neurological prognosis]. / Elevace proteinu S-100B u pacientu s akutním koronárním syndromem po resuscitaci je prediktorem nepríznivé neurologické prognózy.

INTRODUCTION: The annual incidence of out-of-hospital cardiac arrest is around 90-190 cases per 100 000 inhabitants. The limiting factor for further prognosis of patients after out-of-hospital arrest is their neurological status. The S100B protein is mainly the nervous system cells product, its glial-specific and mostly expressed by astrocytes. It has been shown that after circulatory arrest its increased level correlates with the prognosis of patients. Work aims to determine the level of protein S100B in the group of patients with acute myocardial infarction without circulatory arrest, and compare it to the value in patients with acute myocardial infarction after out-of-hospital resuscitation. METHODS: 24 patients were evaluated after out-of-hospital resuscitation for the malignant arrhythmias during acute coronary syndrome (ACS). All patients were treated with mild therapeutic hypothermia. The control group consisted of 19 patients with ACS. The sample for the determination of S-100B was taken immediately on admission. Neurological status was evaluated according to the CPC scores (Cerebral Performance Categories) at discharge, patients were divided into 3 groups: CPC1 - good condition, CPC2 - moderate neurological disability, CPC3-5 - serious neurological impairment, coma or death. RESULTS: The values of protein S-100B fluctuated, in patients with no resuscitation, in range between 0.038 to 0.204 pg/ml. In patients after resuscitation without subsequent neurological disability (CPC 1) was range 0.077 to 0.817 pg/ml, in patients with moderate to severe neurological disability (CPC 2) was range 0.132-2.59 pg/ml, patients with severe neurological disabilities or deaths had S-100B levels from 0.70 to 8.53 pg/ml. According to ROC analysis we found the cut-off value for the S-100B. Cut-off value for probably a good neurological condition is < 0.23 pg/ml (specificity 93%, sensitivity 70%), and value testify for supposed severe neurological disability or death is > 1.64 pg/ml (specificity 95%, sensitivity 83%). CONCLUSION: Protein S-100B is one of the early and sensitive markers of severe brain damage in patients after cardiac arrest. Its early determination can help in prediction of patient neurological condition and help doctors to decide further action.

DnaK and GroEL chaperones are recruited to the Bacillus subtilis membrane after short-term ethanol stress.

AIMS: To find out membrane tolerance strategy to ethanol in Bacillus subtilis that possesses a powerful system of protection against environmental stresses. METHODS AND RESULTS: Cytoplasmic membranes of B. subtilis were severely affected by even short-term exposure to 3% (v/v) ethanol: the growth rate and membrane protein synthesis were markedly reduced, and no adaptive alterations in phospholipids were detected. Simultaneously, steady-state DPH fluorescence anisotropy (r(ss)) showed that the membrane rigidity increased substantially. Analysis of the membrane phosphoproteome using in vitro labelling with [γ-(32) P]ATP revealed the association of DnaK and GroEL chaperones with membrane, indicating a stress induction process. Upon a long-term 3% (v/v) ethanol stress, the cell growth accelerated slightly and the composition of polar head groups and fatty acids of membrane phospholipids underwent an extensive reconstruction. Correspondingly, membrane fluidity turned back to the original r(ss) values of the control cells. CONCLUSIONS: In B. subtilis, the adaptive response to short-term ethanol stress comprises the recruitment of molecular chaperones on the impaired membrane structure; consequently, the phospholipid synthesis is restored and membrane fluidity adapts properly to the continuing ethanol stress. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings underline the role of membrane lipids in establishing tolerance towards ethanol and also suggest the contribution of molecular chaperones to the membrane and cell recovery.

[Acute heart failure and early development of left ventricular dysfunction in patients with ST segment elevation acute myocardial infarction managed with primary percutaneous coronary intervention]. / Akutní srdecní selhání a casný rozvoj dysfunkce levé komory a patientu s akutním infarktem myokardu s elevacemi ST lécených primární perkutánní koronární intervencí.

BACKGROUND: Acute heart failure during ST elevation myocardial infarction (STEMI) makes worse prognosis. The aim of the work was to find independent factors with relationship to acute heart failure (AHF) and the early development of left ventricular dysfunction within the prospective followed patients with STEMI. METHODS: A total of 593 patients with STEMI treated by primary PCI (164 patients with AHF) were the study population. The activity of BNP and NT-ProBNP were measured at hospital admission and 24 h after MI onset. Left ventricular angiography was done before PCI; echocardiography was undertaken between the third and fifth day after MI. RESULTS: The patients with AHF had higher level of glycaemia, creatinine, uric acid, HDL-cholesterol, leukocytosis and natriuretic peptid. The total hospital mortality was 3.7%. 0.2% within the patients without AHF, 3.2%, 14.3%, resp. 63.6% within the patients with mild AHF, with pulmonary oedema, resp. with cardiogenic shock. The patients with AHF had lower ejection fraction (45.4 +/- 11.9% vs 53.0 +/- 10.3%). According to the multiple logistic regression we found higher glycaemia, age, heart rate, anterior wall MI, lower aortic pulse pressure and collaterals of infarct related artery as factors with independent relationship to AHF. Higher glycaemia, age, heart rate, anterior wall MI and lower aortic pulse pressure were found as independent factors with relationship to left ventricular dysfunction. According to ROC analysis possible cut off corresponding with AHF we suggested 29.5 mm Hg for LVEDP, 28.5 for dP/dt/P, 9.5 mmol/l for glycaemia, 50 mm Hg for aortic pulse pressure. CONCLUSIONS: Our results found the development of AHF in one third of patients with STEMI. AHF increases the risk of in-hospital mortality and the risk depends upon severity of failure. As the independent factors with relationship to development of AHF or left ventricular dysfunction we detected higher glycaemia, heart rate, anterior wall MI, age. Lower risk had patients with higher aortic pulse pressure.

Characterization of residual coronary sinus-related tachycardia during ablation of longstanding persistent atrial fibrillation.

PURPOSE: The aim was to characterize the coronary sinus (CS)-related tachycardia that occurred as the last residual arrhythmia and required ablation within the CS or great cardiac vein to restore sinus rhythm (SR) in patients with primary longstanding persistent AF. METHODS: The study included 23 patients in whom stable SR was restored by ablation inside the vein during the first or repeat ablation. RESULTS: The 23 subjects represented 23% of the 99 patients in whom SR was restored by ablation. A reentry tachycardia confined to the CS musculature was suggested in 8 (35%) patients, and a peri-mitral reentry circuit was present in 14 (61%) patients. Twenty (87%) patients have remained free from arrhythmia and class I or III antiarrhythmic drugs for 33 +/- 10 (12-53) months. CONCLUSION: A majority of the residual CS-related tachycardias exhibit properties of reentry, one third utilizing the CS musculature as a reentry substrate independent of the atrial myocardium.

[Immediate and long-term results of conventionally performed radiofrequency catheter ablations of paroxysmal atrial fibrillation]. / Radiofrekvencní katetrová ablace paroxyzmální fibrilace síní konvencní metodou, bezprostrední a dlouhodobé výsledky.

INTRODUCTION: Atrial fibrillation is the most frequent cardiac arrhythmia. Epidemiological studies show sharp increase of incidence and prevalence of atrial fibrillation all over the world. Atrial fibrillation is becoming to be a serious problem, not only clinical, but even social and economical. Aim of the paper was to evaluate immediate and long-term results of radiofrequency catheter ablation of paroxysmal atrial fibrillation at Dpt. of Internal Medicine-Cardiology, University Hospital Brno. METHODS: The patients were indicated for ablation, when the anti-arrhythmic therapy was ineffective. End-point of the ablation was disconnection of myocardial sleeves between left atrium and pulmonary veins and complete electrical isolation of pulmonary veins. GROUP OF THE PATIENTS, RESULTS: There were 67 catheter ablations of paroxysmal atrial fibrillation performed within the years 9/2004 to 12/2006 at our department, out of the whole amount of 1,285 ablations of supraventricular tachyarrhythmias from 1995 to 2006. There were 27 women (40%) and 40 men (60%) in our group of patients, with the mean age 56.9 +/- 9.5 years. The average ejection fraction of left ventricle was 62 +/- 5%, left atrial dimension 42.8 +/- 6 mm. The mean follow-up period was 16.9 +/- 10.9 months. The patients were treated before and after the ablation by 1 anti-arrhythmic drug in 44.8 vs 50%, by 2 drugs in 40.3 vs 14.9% and by 3 drugs in 10.4 vs 9%, respectively. The percentage of patients without any anti-arrhythmic drug increased after successful ablation from 2.9 to 25.4%, the percentage of patients using amiodarone decreased from 29.8 to 16.4%, propafenon from 29.8 to 16.4% and sotalol from 26.8 to 10.4% respectively. The median of RF application duration was 43.8 min, fluoroscopy time 43.8 min and procedure duration 240 min. The success rates were 87.5% in year 2004, 77.4% in 2005 and 79.2% in 2006. CONCLUSION: Catheter ablation of paroxysmal atrial fibrillation has become a routine curative method in symptomatic patients without major structural heart disease, with ineffective anti-arrhythmic treatment. Ablation was associated with significant reduction of anti-arrhythmic and anticoagulation therapy.

[Coronary artery disease with premature manifestation in young patients]. / Ischemická choroba srdecní s predcasnou manifestací u mladých pacientu.

INTRODUCTION: Coronary artery disease (CAD) affects in lower percentage even younger individuals. This paper describes group of young patients aged 40 years or less with premature manifestation of CAD, including analysis of risk factors, severity of coronary arteries affection, management and follow-up lasting up to 7 years. PATIENTS AND METHODS: There were 98 patients included retrospectively, in whom macroscopic affection of coronary arteries was diagnosed by coronary angiography within the years 2000-2007. 68 of the patients were indicated to coronary angiography urgently due to acute coronary syndrome (ACS), 44 of them due to acute myocardial infarction with ST elevations. The patients were called for further co-operation and 45 of them (45.9%) were re-examined completely and they will be observed prospectively. The results show overall good short-term prognosis of these patients and confirm importance of early invasive management and revascularisation. One-year mortality of the patients with ACS was 1.9%. 80% out of 45 completely re-examined patients have ejection fraction of left ventricle better than 50% and 84% ofthem is without any anginal symptoms. However, our results show inadequate secondary prevention in these patients. 15 patients (33%) still smoke, 20 (44%) is over-weighted. Only 22 patients (49%) had LDL-cholesterol level bellow 2.5 mmol/l and even only 15 patients (33%) had blood pressure below 130/80 mm Hg. CONCLUSIONS: Management of these basic risk factors should improve even the long-term prognosis of our patients.

[Superior mesentery artery embolization as a complication of the primary angioplasty solved by local thrombolysis]. / Embolizace vetví a. mesenterica superior jako komplikace direktní angioplastiky resená lokální trombolýzou.

Acute mesentery artery embolization is a rare complication of invasive catheterizations. The incidence is unknown. In case of late diagnosis the mortality may reach up to 93%. Acute abdominal pain, vomitus, rapid and sudden bowel evacuation with or without blood are the typical symptoms of the disease. Plain X-Rays of abdomen or CT tomography may show no signs of intestinal ischaemia. The diagnostic method to choose is either spiral CT angiography or contrast angiography, respectively. The most common therapeutical approach is surgical revascularization but in selected cases it is feasible to perform local thrombolysis with a microcatheter placed directly into the artery with embolus. We report a case of a man who was admitted with an acute myocardial infarction who underwent primary angioplasty with implantation ofa bare-metal stent. After the procedure he developed severe and progressive abdominal pain as a result of acute superior mesentery artery embolization. In this patient we performed a local thrombolysis with rt-PA (alteplase) with a great technical success and immediate pain relief, with no need of surgical revision. Our approach was concordant to recommendations cited in this article.

[Repolarization homogeneity in patients after acute myocardial infarction assessed from long-term 12-lead electrocardiographic recordings]. / Homogenita repolarizace u patientu po akutním infarktu myokardu hodnocená z dlouhodobých 12svodových elektrokardiografických záznamu.

BACKGROUND: Abnormal heterogeneity of myocardial electrophysiologic processes increases the risk of malignant arrhythmias. The aim of the studywas to assess changes ofrepolarization homogeneity in patients after acute myocardial infarction (MI) using morphological parameters obtained from long-term 12-lead electrocardiographic recordings. METHODS: In the group of 200 patients (45 females, 155 males) a long-term (10 minutes supine) 12-lead electrocardiographic recording (SEER MC, GE Medical) was performed 48-72 hours after acute myocardial infarction. The following parameters were calculated using experimental software: total cosine R to T (TCRT) and Twave residuum (TWR). The results were correlated with Q wave evolution and left ventricular ejection fraction (LVEF). RESULTS: Distinguishing the MI type (Q vs nonQ) the following values were obtained: TCRT: 0.17 +/- 0.61 vs 0.16 +/- 0.49, p = 0.52, absolute TWR: 21,200 +/- 21,700 vs 25,700 +/- 29,300, p = 0.3, relative TWR: 0.0012 +/- 0.0017 vs 0.0017 +/- 0.0026, p = 0.28. Stratification according to LVEF (< or = 40% vs > 40%) led to: TCRT: -0.03 +/- 0.66 vs 0.25 +/- 0.54, p = 0.01, absolute TWR: 29,700 +/- 32,400 vs 21,300 +/- 21,500, p = 0.14, relative TWR: 0.0021 +/- 0.0047 vs 0.0013 +/- 0.0021, p = 0.48. CONCLUSION: TCRT is a robust measurement of the spatial angle between the QRS complex and T wave loops which is related to LVEF. The results concerning TWR might indicate that this parameter is independent of LVEF, which needs to be confirmed in further analyses in a larger population.

Mutation analysis of candidate genes SCN1B, KCND3 and ANK2 in patients with clinical diagnosis of long QT syndrome.

The long QT syndrome (LQTS) is a monogenic disorder characterized by prolongation of the QT interval on electrocardiogram and syncope or sudden death caused by polymorphic ventricular tachycardia (torsades de pointes). In general, mutations in cardiac ion channel genes (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2) have been identified as a cause for LQTS. About 50-60 % of LQTS patients have an identifiable LQTS causing mutation in one of mentioned genes. In a group of 12 LQTS patients with no identified mutations in these genes we have tested a hypothesis that other candidate genes could be involved in LQTS pathophysiology. SCN1B and KCND3 genes encode ion channel proteins, ANK2 gene encodes cytoskeletal protein interacting with ion channels. To screen coding regions of genes SCN1B, KCND3, and 10 exons of ANK2 following methods were used: PCR, SSCP, and DNA sequencing. Five polymorphisms were found in screened candidate genes, 2 polymorphisms in KCND3 and 3 in SCN1B. None of found polymorphisms has coding effect nor is located close to splice sites or has any similarity to known splicing enhancer motifs. Polymorphism G246T in SCN1B is a novel one. No mutation directly causing LQTS was found. Molecular mechanism of LQTS genesis in these patients remains unclear.

Detection of lateral heterogeneity in the cytoplasmic membrane of Bacillus subtilis.

Lateral heterogeneity in the cytoplasmic membrane of Bacillus subtilis was found by using density gradient centrifugation. Crude membranes (CM) present in the whole cell lysate were separated into three fractions of increasing density (F, CI, CII). Substantial difference exists in the amount of protein recovered from these fractions, the relative ratio being 15 : 35 : 50. The qualitative protein composition (by SDS-PAGE) of the fractions varies markedly as well. The lipid components extracted from the fractions are also distributed in different proportions, viz. 40 : 40 : 20. The spectrum of fatty acids (FA), detected in lipids of F fraction and analyzed by GC-MS exhibits the same profile as that found in CM; in contrast, fractions CI and CII undergo extensive FA reconstruction. Thermotropic behavior of fractions measured by the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene indicates significant variations of microviscosity (r(s)) within the F, CI and CII fractions. The protein-to-lipid ratio plays evidently a key role in affecting the physical state of the cytoplasmic membrane. Microdomains of different density coexist in the membrane and exhibit heterogeneity in both chemical composition and "physical state"; the increased de novo synthesis of FA induced by the cold exclusively in fractions CI and CII indicates correlation with an altered physiological state of bacterial metabolism.

[QT dynamicity in risk stratification in patients after myocardial infarction]. / QT dynamicita v rizikové stratifikaci u pacientu po infarktu myokardu.

BACKGROUND: Ventricular repolarization abnormalities are associated with increased risk of sudden cardiac death in patients after myocardial infarction. The aim of this study is to assess QT dynamicity - QT/RR relationship - in patients after myocardial infarction and its contribution to risk stratification of sudden cardiac death. METHODS: In a group of patients with diagnosis of acute myocardial infarction a long term ECG recording was performed 48-72 hours after myocardial infarction (MARS Unity Workstation, GE Medical Information Technologies). Patients with unstable circulation, artificial pulmonary ventilation, left bundle brach block, atrial fibrillation and paced rhythm were excluded. Analysis of QT dynamicity was performed by QT Guard software (GE Medical Information Technologies). QT/RR relationship is expressed by linear regression as QT = = aRR + b where "a" is termed "slope". RESULTS: Assessment of QT dynamicity was possible in 215 ECG recordings. In 6-month follow-up 2 patients died and another was successfully resuscitated for primary ventricular fibrillation. Six-month mortality resp. mortality + resuscitation was 0.9 %, resp. 1.4 %. Therefore statistical evaluation was not possible. In the 3 mentioned individuals the slope values were 0.333, 0.249 and 0.342. CONCLUSIONS: Mortality of up-to-date-treated patients after myocardial infarction is low. Therefore, in such patients it is not possible to assess QT dynamicity as a risk factor in midterm follow-up. Limitation of the method is the necessity of substantial selection of patients elegible for analysis and dependance on necessary equipment.

[Extension of QT interval as a consequence of risk factor accumulation--case study]. / Prodlouzení QT intervalu jako dusledek kumulace rizikových faktoru: kazuistika.

BACKGROUND: Many non-cardiovascular drugs have a potential for QT interval prolongation. This phenomenon can be related to occurence of ventricular tachycardia torsades de pointes, syncopi and even sudden death. DESCRIPTION OF THE CASE: A female patient treated with antracycline cytostatics developed a depression of left ventricle ejection fraction. At the same time she was administered 2 common drugs with proarrhythmic potential--terfenadine and itraconazole. In this patient hypokalemia also occured. Combination of the above mentioned risk factors led to QT interval prolongation and frequent ventricular tachycardias torsades de pointes degenerating in ventricular fibrillations with need of repeated defibrillations. Both drugs were withdrawn and dysiontaemia corrected. Then arrhythmias disappeared and QT interval completely normalized. In this patient the congenital long QT syndrome was not proved. DISCUSSION AND CONCLUSIONS: In proarrhythmic effect of non-cardiovascular drugs the following factors play role: predisposition of a particular individual, "repolarization reserve", interindividual differences in drug metabolism. The risk factors are age, sex, dysiontaemia, heart disease and drug interactions. By different choice of medication and attention to risk factors teh life threat to the described patient could have been avoided.

[Mutational analysis of LQT genes in individuals with drug induced QT interval prolongation]. / Mutacní analáza LQT genu u jedincu s polékovým prodlouzením QT intervalu.

BACKGROUND: In a long list of non-cardiovascular drugs a risk of QT interval prolongation and thus an increased risk of malignant arrhythmias has been described. The precise mechanism remains unclear. Many of these drugs are potent blockers of cardiac ion channels. Thus, prolongation of repolarization could be caused by latent ion channel genes mutations which are revealed under stress conditions. GROUP OF PATIENTS AND METHODS: Patients were recruited in screening of antipsychotic drugs with proarrhythmic potential, another sporadic cases were reffered from regional hospitals. In 13 individuals pathologic values of corrected QT interval (> 0.44 s in males, > 0.46 s in females) were observed. Eleven patients gave their consent to mutational analysis of KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2 and KCNJ2 genes (associated with congenital long QT syndrome). RESULTS: At present complete results of mutational analysis are available in 8 patients. In 5 individuals changes in DNA sequence were found which are considered normal variants according to the literature (nucleotide and aminoacid polymorphisms, intronic variants). In 1 male a KCNQ1 gene mutation A590T was identified (yet not reported in literature). CONCLUSION: Mechanisms of drug-induced QT interval prolongation is complex and it cannot be explained simply by ion channel disorders.

Immuno-electron localization of DNA in chondriolites of Saccharomyces cerevisiae mitochondria.

Under electron microscope, the matrix of sectioned mitochondria exhibits ribosomes and an oval, electron-transparent zone which is devoid of ribosomes and is named chondriolite. Fine fibers or clumps of an electron-dense material appeared in this zone after several fixation and contrasting steps and were identified with mitochondrial DNA by cytologists. To verify this assumption, we labeled DNA by a monoclonal antibody and a secondary antibody coupled to immunogold. The label was observed in the nucleus and in the chondriolite zone of sectioned mitochondria. Because the ultrastructure of chondriolites resembles that of nucleoids of prokaryotes, we suggest the term mitochondrial nucleoid for the zone of mitochondrial matrix devoid of ribosomes and containing DNA.