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Biomedical subjects

Kenshi Hayashi

Publications and source records attributed to Kenshi Hayashi.

At least 19 recordsLinked to original sources
PubMed2003

A novel missense mutation in the myosin binding protein-C gene is responsible for hypertrophic cardiomyopathy with left ventricular dysfunction and dilation in elderly patients.

OBJECTIVES: We studied the clinical features of hypertrophic cardiomyopathy (HCM) caused by a novel mutation in the myosin binding protein-C (MyBP-C) gene in patients and family members of Japanese descent. BACKGROUND: Previous reports have demonstrated that the clinical features of HCM associated with mutations in the MyBP-C gene include late onset and a favorable clinical course. Recently, some mutations in genes encoding sarcomeric proteins have been reported to be a cause of dilated cardiomyopathy (DCM), as well as HCM. However, mutations of the MyBP-C gene have not been reported as a cause of DCM up to now. METHODS: We analyzed MyBP-C gene mutations in 250 unrelated probands with HCM and in 90 with DCM. We used electrocardiography (ECG) and echocardiography to determine clinical phenotypes. RESULTS: We identified 17 individuals in 8 families (7 HCM, 1 DCM) with an Arg820Gln mutation in the MyBP-C gene. Overall, 2 (40%) of 5 carriers age >70 years displayed "burnt-out" phase HCM, and one of them had been diagnosed as having DCM before genetic identification. The disease penetrance in subjects age >50 years was 70% by echocardiography and 100% by ECG, and that in those age <50 years was 40% and 50%, respectively. CONCLUSIONS: Elderly patients with Arg820Gln mutation may show "burnt-out" phase HCM, and patients with this mutation may be included among those diagnosed as having DCM. Screening of patients with DCM, as well as HCM, for this mutation is of significant importance because patients with this mutation may be diagnosed clinically as having DCM.

Adolescent↗
PubMed2003

Hemodynamic changes and prognosis in patients with hypertrophic cardiomyopathy and abnormal blood pressure responses during exercise.

BACKGROUND: An abnormal blood pressure response (BPR) during exercise has been proposed as a risk factor for sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). Some patients with HCM show systolic dysfunction during exercise. HYPOTHESIS: The aim of this study was to clarify the hemodynamic response during exercise and prognosis in patients with HCM and abnormal BPR. METHODS: Sixty-five patients with HCM underwent radionuclide monitoring of left ventricular function and measurement of blood pressure during supine ergometer exercise. Thereafter, cardiac events were recorded for an average period of 76 months. RESULTS: Seven of 65 patients had abnormal BPR, while the others had normal BPR. Changes of heart rate and systemic vascular resistance during exercise did not differ between the two groups. Stroke volume did not increase in the abnormal BPR group but did in the normal BPR group. During a mean follow-up period of 76 months, three of the seven patients (43%) with abnormal but only one patient (2%) with normal BPR suffered a malignant arrhythmia. CONCLUSIONS: Abnormal BPR occurred in about 11% of patients with nonobstructive HCM and was associated with a high prevalence of cardiac events. The predictor of abnormal BPR during exercise may not be an abnormal response of systemic vascular resistance and heart rate, but the lack of an appropriate increase in stroke volume.

Blood Pressure↗
PubMed2003

Clinical and electrophysiological characterization of a novel mutation (F193L) in the KCNQ1 gene associated with long QT syndrome.

KCNQ1 is a gene encoding an alpha subunit of voltage-gated cardiac K(+) channels, with properties similar to the slowly activating delayed rectifier K(+) current, and one of the genes causing long QT syndrome (LQTS). However, genotype-phenotype correlations of the KCNQ1 gene mutations are not fully understood. The aims of this study were to identify a mutation in the KCNQ1 gene in patients with LQTS, and to characterize the clinical manifestations and electrophysiological properties of the mutation. We screened and identified mutations by PCR, single-strand conformational polymorphism analysis and DNA sequencing. We identified a novel mutation [Phe193Leu (F193L)] in the KCNQ1 gene in one family with LQTS. The patients with this mutation showed a mildly affected phenotype. The proband was a 17-year-old girl who had a prolonged QT interval. Her elder brother, father and paternal grandmother also had the mutation. None of them had any history of syncope. Sudden death was not found in this family. Next, we studied the electrophysiological characteristics of the F193L mutation in the KCNQ1 gene using the expression system in Xenopus oocytes and the two-microelectrode voltage-clamp technique. Co-expression of F193L KCNQ1 with the K(+) channel minK suppressed peak (by 23.3%) and tail (by 38.2%) currents compared with those obtained by the combination of wild-type (WT) KCNQ1 and minK. Time constants of current activation in F193L KCNQ1 and F193L KCNQ1+minK were significantly slower than those of WT KCNQ1 and WT KCNQ1+minK. This electrophysiological study indicates that F193L causes less severe KCNQ1 current suppression, and thereby this mutation may result in a mildly affected phenotype.

Adolescent↗
PubMed2003

Diagnosis of autosomal dominant retinitis pigmentosa by linkage-based exclusion screening with multiple locus-specific microsatellite markers.

PURPOSE: To describe a hierarchical approach for efficient genetic diagnosis of autosomal dominant retinitis pigmentosa (adRP). METHODS: Forty di-, tri-, or tetra-nucleotide repeats tightly linked to 10 genes known to be responsible for adRP were identified from the human genome sequence and used as markers in multiplex amplification and genotyping, followed by linkage analysis. Discordance of cosegregation of markers and the disease excluded the majority of the examined genes as candidates, and mutation screening for the remaining genes was performed. RESULTS: With this strategy, examination of an adRP-affected family indicated that 3 of 10 candidate genes segregated concordantly with the disease. Further searches for mutations revealed a novel insertion and deletion in the last exon of a splicing factor gene, PRPF8. CONCLUSIONS: This systematic approach facilitates the molecular diagnosis of adRP, which is known to have a highly heterogeneous genetic background.

Carrier Proteins↗
PubMed2003

Q-T peak dispersion in congenital long QT syndrome: possible marker of mutation of HERG.

Congenital long QT syndrome (LQTS) is caused by mutations in various cardiac potassium or sodium channel genes, with 6 different genotypes thus far identified. However, it is unknown whether these genotypes can be differentiated by QT variables. The electrocardiograms obtained from 16 patients with a mutation in KCNQ1 (LQT1), 7 patients with a mutation in HERG (LQT2) and 20 control subjects were analyzed. The corrected QT interval (QTc), Q-T peak interval (QTpc) and dispersion of QTc or QTpc were measured in 6 precordial leads. The corrected interval from T peak to T end (Tpec) was measured in lead V(5). The maximum QTc, QTc dispersion, and Tpec were significantly increased in the LQT1 and LQT2 patients than in the controls. However, there were no significant differences in these indices between the LQT1 and LQT2 patients. In contrast, QTpc dispersion was significantly increased in the LQT2 patients (78+/-25 ms) compared with the LQT1 patients (29+/-15 ms) and controls (26+/-19 ms). These results suggest that increased lag of the peak of the T wave in each precordial lead (QTpc dispersion) may be a possible index to differentiate LQTS patients with HERG mutation from those with KCNQ1 mutation.

Adult↗
PubMed2003

In-hospital outcome in octogenarians with acute coronary syndrome undergoing emergent coronary angiography.

Very elderly patients have higher mortality rates than younger patients after acute coronary syndrome (ACS). However, the mechanism by which increasing age contributes to such mortality remains unclear. In addition, the efficacy and safety of invasive coronary procedures for octogenarians with ACS have not been well established. We compared the clinical characteristics and in-hospital outcome of 193 octogenarians (mean age, 83 years) with those of 1,462 younger patients (mean age, 64 years) with ACS who underwent emergent coronary angiography. Octogenarians included a greater number of females, had higher rates of cerebrovascular disease and multivessel disease, a higher Killip class, a higher Forrester class, and lower rates of smoking, diabetes, and hypercholesterolemia than the younger subjects. Interventions, including percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG), were performed less frequently in octogenarians than in younger patients (88.0% versus 90.8%). The procedural success rate in octogenarians did not differ from that in younger patients. However, the in-hospital mortality rate for the octogenarians was about three times higher than for the younger patients (19.2% versus 6.9%). Multivariate analysis revealed that the predictors of in-hospital mortality in the octogenarians were a higher Killip class and a higher Forrester class. Octogenarians with ACS had fewer coronary risk factors and a similar success rate for the intervention, but had more greatly impaired hemodynamics and higher in-hospital mortality than the younger patients. Therefore, impaired myocardial reserve may contribute to a large portion of in-hospital deaths in octogenarians with ACS.

Aged↗
PubMed2002

Molecular bases for human complement C7 polymorphisms, C7*3 and C7*4.

Complement C7 is one of the components of membrane attack complex (MAC) generated by the terminal complement cascade. C7 protein is polymorphic and most of its polymorphisms have been identified using isoelectric focusing (IEF), which detects protein charge differences. To date, the molecular bases of the polymorphisms detected by IEF have not been determined. In this paper, we describe the structural bases of two C7 IEF-detected polymorphisms, C7*3 and C7*4, both of which are common in Asian populations. C7*3 resulted from substitution of cysteine (Cys) at amino acid residue 106 by charged arginine (Arg; C106R), while charged lysine (Lys) at amino acid residue 398 was replaced by neutral glutamine (Gln; K398Q) in C7*4. As C7*3 is hypomorphic, it is important to study its possible associations with diseases such as immunological disorders and infections. We present genetic bases for this C7 polymorphism, which we determined using polymerase chain reaction (PCR)-based genotyping, a simple and accurate method suitable for large-scale studies.

Base Sequence↗
PubMed2002

Characterization of caspase-8L: a novel isoform of caspase-8 that behaves as an inhibitor of the caspase cascade.

Caspase-8 (Fas-associating protein with death domain-like interleukin-1beta- converting enzyme [FLICE]/MACH/Mch5) belongs to a family of cysteine proteases presumed to be the apex of the apoptotic signaling pathways. We recently reported the presence of a novel isoform of caspase-8, named caspase-8L, generated by the alternative splicing of human caspase-8 gene, from human peripheral blood lymphocytes by reverse transcriptase-polymerase chain reaction. We herein report a functional analysis of caspase-8L in the Fas-mediated apoptotic pathway. Caspase-8L is missing the catalytic site of caspase-8 but retains 2 N-terminal repeats of the death-effector domain. The caspase-8L messenger RNA was detected in various tissues but not in any cell lines examined. In human peripheral blood lymphocytes, caspase-8L was strongly suggested to be expressed at the protein level. In MCF-7 cells, caspase-8L transfection itself did not affect cell viability but instead inhibited the apoptosis induced by the cotransfection of caspase-8 in a dominant negative manner. Moreover, Fas-mediated apoptosis was inhibited in caspase-8L-transfected Jurkat cells, which were associated with a reduction in the caspase-8 catalytic activity. In vitro binding assays demonstrated that caspase-8L bound to FADD (Fas-associating protein with death domain) and caspase-8a and blocked the binding of caspase-8 to FADD. In in vivo binding assays, transfected caspase-8L bound to endogenous FADD. Thus, caspase-8L acts as an inhibitor of caspase-8 by interfering with the binding of caspase-8 to FADD and is involved in the regulation of Fas-mediated apoptosis.

Amino Acid Sequence↗
PubMed2002

Ordered catenation of sequence-tagged sites and multiplexed SNP genotyping by sequencing.

We describe a method for the efficient genotyping of SNPs, involving sequencing of ordered and catenated sequence-tagged sites (OCS). In OCS, short genomic segments, each containing an SNP, are amplified by PCR using primers that carry specially designed extra nucleotides at their 5'-ends. Amplification products are then combined and converted to a concatamer in a defined order by a second round of thermal cycling. The concatenation takes place because the 5'-ends of each amplicon are designed to be complementary to the ends of the presumptive neighboring amplicons. The primer sequences for OCS are chosen using newly developed dedicated software, OCS Optimizer. Using sets of SNPs, we show that at least 10 STSs can be concatenated in a predefined order and all SNPs in the STSs are accurately genotyped by one two-way sequencing reaction.

Asian People↗
PubMed2002

A single-strand conformation polymorphism method for the large-scale analysis of mutations/polymorphisms using capillary array electrophoresis.

We present a high-throughput single-strand conformation polymorphism (SSCP) method, performed on a commercially available capillary array DNA sequencer. We tested various sieving matrices and electrophoretic conditions, using 51 DNA fragments which included 45 fragments carrying only one single nucleotide polymorphism (SNP), 4 fragments having two SNPs and 2 fragments with insertion or deletion. Resolution of alleles was improved by increasing concentrations of both sieving matrices and buffers, and all examined polymorphisms of DNA fragments were detected, most of them (45 fragments) as clearly split allele peaks in heterozygotes. Allele frequencies of SNPs can be estimated accurately by determining the relative amounts of alleles in pooled DNA. In this method, the turn-around time for the analysis of 96 samples is less than 3 h. These results demonstrate that capillary array-based SSCP is an efficient and accurate technique for the large-scale quantitative analysis of mutations/polymorphisms.

DNA Mutational Analysis↗
PubMed2002

T-peak to T-end interval may be a better predictor of high-risk patients with hypertrophic cardiomyopathy associated with a cardiac troponin I mutation than QT dispersion.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) associated with a deletion of lysine 183 (K183del) in the cardiac troponin I (cTnI) gene suffer sudden cardiac death at all ages. However, the correlation between QT variables and sudden cardiac death in these patients remains uncertain. HYPOTHESIS: We evaluated the correlation between QT variables and sudden cardiac death and/or ventricular tachyarrhythmia (SCD/VT) in patients with HCM associated with the cTnI mutation. METHODS: We analyzed 10 probands with HCM associated with the cTnI gene K183del and their family members. The subjects were divided into three groups: Group A (n = 7), mutation carriers with SCD/VT; Group B (n = 16), mutation carriers without SCD/VT; Group C (n = 24), no mutation carriers. QT intervals were corrected using Bazett's formula. RESULTS: Maximum QTc and corrected QT dispersion were significantly longer in Groups A and B than in Group C. However, there were no differences in either parameter between Groups A and B. On the contrary, the peak-to-end interval of T wave/QT interval in V5 (Tpe) in Group A was significantly longer than that in Groups B and C. Logistic regression analysis revealed that Tpe was a good clinical predictor for SCD/VT in patients with HCM in this study. CONCLUSIONS: These results suggest that Tpe rather than QT dispersion may be one of the best predictors for SCD/VT in patients with HCM associated with the K183del mutation in the cTnI gene.

Adult↗
PubMed2002

Characterization of a novel missense mutation E637K in the pore-S6 loop of HERG in a patient with long QT syndrome.

OBJECTIVE: In a 32-year-old woman with marked QT prolongation (QTc=0.61 s) and repeated episodes of syncope, we identified a single pertinent base substitution (G to A at 1909) in HERG by genetic analysis. This novel missense mutation is predicted to cause an amino acid substitution of lysine for glutamic acid at position 637 (E637K) in the pore-S6 loop. Therefore, we investigated the role of a glutamic acid at the vicinity of the pore in HERG channels by mutating it to a lysine. METHODS: We characterized the electrophysiological properties of the E637K mutation using a Xenopus oocyte heterologous expression system. RESULTS: Injection of the E637K mutant cRNA alone into Xenopus oocytes did not result in any expression of detectable currents. Coexpression of wild-type (WT) and E637K (E637K/WT) elicited only about 30% of the control peak tail current that was expected from expression of WT alone. Kinetic analyses revealed that E637K/WT decelerated the rate of channel activation and enhanced steady-state inactivation. Furthermore, the reversal potentials at low concentrations of K+ showed a positive shift in oocytes injected with E637K/WT compared with WT alone. CONCLUSIONS: These results indicated that the E637K mutation causes apparent dominant negative suppression of WT HERG channel function and suggest that E637 at the Pore-S6 is a crucial component of the activation and inactivation gate of HERG channels.

Adult↗
PubMed2002

Chronologic electrocardiographic changes in patients with hypertrophic cardiomyopathy associated with cardiac troponin 1 mutation.

BACKGROUND: Deletion of lysine 183 (K183del) in the cardiac troponin I (cTnI) gene is one of the mutations that causes hypertrophic cardiomyopathy (HCM). However, the phenotypic expression of this mutation has not been well established. METHODS AND RESULTS: We analyzed 10 probands with HCM associated with a K183del in the cTnI gene, as well as their family members. Forty-seven of these 80 subjects were found to be carriers and 33 were noncarriers. In the carrier subjects, electrocardiogram (ECG) abnormalities were initially noted during the early teenage years preceding echocardiographic abnormalities. Abnormal Q waves were found first and most frequently compared with other ECG abnormalities. Abnormal Q waves were frequently observed in leads II, III, aVF, V5, and V6 in teenage patients, whereas they were observed in many leads in patients >20 years old. The youngest of the 11 patients who had sudden cardiac death among studied pedigrees was a 14-year-old boy. CONCLUSIONS: These results suggest that the first phenotypic manifestation in patients with HCM associated with a K183del mutation in the cTnI gene is abnormal Q waves in leads II, III, aVF, V5, and V6 during the early teenage years. To prevent sudden death in family members of patients with this mutation, it may be necessary to genetically diagnose it before age 10 years and to pay careful attention to any development of abnormal Q waves.

Adolescent↗
PubMed2002

Septal wall thinning and systolic dysfunction in patients with hypertrophic cardiomyopathy caused by a cardiac troponin I gene mutation.

BACKGROUND: Lysine 183 deletion in the cardiac troponin I gene is 1 of the mutations that causes hypertrophic cardiomyopathy (HCM). However, the clinical course and determinants of poor prognosis in patients with this mutation have not been well established. METHODS AND RESULTS: We analyzed 10 probands with HCM caused by this mutation and their family members. Forty-six of these 79 subjects were found to be carriers, and 33 were non-carriers. All non-carriers had a percent fractional shortening (%FS) of >25% at all ages. By contrast, 7 of 24 carriers >40 years of age had a %FS of <25%, and no carriers <40 years of age had a %FS of <25%. The change in interventricular septal thickness and the change in %FS were significantly correlated (R = 0.758; P =.0017). CONCLUSION: These results suggest that about 30% of patients with HCM caused by a lysine 183 deletion mutation in the cardiac troponin I gene have systolic dysfunction develop after 40 years of age, and that patients with this mutation whose interventricular septal thickness shows a serial decrease should be followed-up closely for development of systolic dysfunction.

Adult↗
PubMed2002

Characterization of the biological functions of a transcription factor, c-myc intron binding protein 1 (MIBP1).

The c-myc intron binding protein 1 (MIBP1) is a gigantic zinc finger protein comprising 2,437 amino acids and belonging to the MHC binding protein (MBP) family. MIBP1 is suggested to be a transcription factor involved in various biological functions. We show here that MIBP1 represses c-myc transcription from the major promoter, P2. Screening by the yeast two-hybrid system revealed that the MIBP1 protein interacts with the Ski-interacting protein (SKIP). In vitro pull-down assays and in vivo co-immunoprecipitation experiments confirmed this interaction. The acidic region of MIBP1 was found to be the site of interaction with the N-terminal half of SKIP. In situ hybridization analysis using developing rat embryos revealed that the MIBP1 mRNA is highly expressed in post-mitotic neurons, but the expression in immature neuroepithelium is low. The expression of MIBP1 in adult rat brain is also predominantly in neuronal cells, indicating that MIBP1 is involved in the physiology of mature neuronal cells.

Amino Acid Sequence↗
PubMed2002

Multiplexed analysis of post-PCR fluorescence-labeled microsatellite alleles and statistical evaluation of their imbalance in brain tumors.

Detection of the loss of chromosomal regions in cancerous tissues has diagnostic and prognostic relevance, and the development of a reliable and cost-effective technique for this is clinically important. Here we present an efficient technique for quantitative detection of microsatellite alleles, using a post-PCR fluorescence-labeling procedure and multiplexed analysis. We also present a new statistical method for the interpretation of the data that permits reliable and sensitive evaluation of the allelic status of sampled DNA. A high-resolution analysis of allelic imbalance on chromosomes 1p, 10 and 19q in 28 glioma samples of various types using this method revealed that allelic imbalances are more frequent than have been reported, suggesting the diagnostic value of this method in examining the genetic profiles of gliomas.

Allelic Imbalance↗
PubMed2002

Effects of gender on the number of diseased vessels and clinical outcome in Japanese patients with acute coronary syndrome.

It has been reported that women with acute myocardial infarction (AMI) have a higher short-term mortality rate than men, but the reason is unclear and it is not known if it also applies to unstable angina pectoris (UAP). In addition, most previous studies have not presented angiographic findings. In the present study, the findings from 1,408 patients with AMI (group A: 361 women, 1,047 men) and 332 patients with UAP (group B: 103 women, 229 men) who underwent coronary angiography within 30 days of onset were analyzed. In both groups, the women were older and had a higher rate of hypertension and a lower rate of smoking than the men. There was no significant difference in Killip class or the number of diseased vessels between the women and men in both groups. Interventions (coronary angioplasty and coronary artery bypass grafting) were performed less frequently in the women than in the men (87.2% vs 91.8%, p=0.04) in group A, but not in group B (80.6% vs 81.2%, NS). In both groups, the overall mortality rate during hospitalization was higher in women than in men (group A: 14.4% vs 7.4%, p<0.0001, group B: 7.8% vs 1.7%, p=0.007). Multivariate analysis revealed that female gender was an independent predictor of in-hospital mortality in group B (odds ratio (OR): 6.4, 95% confidence interval (CI) 1.1-37.0, p=0.04), but not in group A (OR: 1.7, 95%CI 0.98-2.9, p=0.06). The independent predictors of in-hospital mortality, other than female gender were age, prior congestive heart failure, prior cerebrovascular disease and a higher Killip class in group A, and in both groups a higher number of diseased vessels. In conclusion, Japanese women with acute coronary syndromes present with similar angiographic findings and hemodynamics, but have a higher in-hospital mortality than male patients. Our results suggest that older age may be a potential explanation for the higher in-hospital mortality in women with AMI, but female gender itself may be an important predictor for it among those with UAP.

Acute Disease↗