K. Komamura

Haplotype structures of the UGT1A gene complex in a Japanese population.

Genetic polymorphisms of UDP-glucuronosyltransferases (UGTs) are involved in individual and ethnic differences in drug metabolism. To reveal co-occurrence of the UGT1A polymorphisms, we first analyzed haplotype structures of the entire UGT1A gene complex using the polymorphisms from 196 Japanese subjects. Based on strong linkage disequilibrium between UGT1A8 and 1A10, among 1A9, 1A7, and 1A6, and between 1A3 and 1A1, the complex was divided into five blocks, Block 8/10, Block 9/6, Block 4, Block 3/1, and Block C, and the haplotypes for each block were subsequently determined/inferred. Second, using pyrosequencing or direct sequencing, additional 105 subjects were genotyped for 41 functionally tagged polymorphisms. The data from 301 subjects confirmed the robustness of block partitioning, but several linkages among the haplotypes with functional changes were found across the blocks. Thus, important haplotypes and their linkages were identified among the UGT1A gene blocks (and segments), which should be considered in pharmacogenetic studies.

Which factors predict the recovery of natural heart function after insertion of a left ventricular assist system

BACKGROUNDnRecent reports have demonstrated that use of a left ventricular assist system (LVAS) can initiate recovery of cardiac function, and subsequent weaning from the LVAS has attracted considerable interest. In this study we investigated reliable predictors of LVAS weaning.nnnMETHODSnEighty-two patients underwent LVAS implantation between April 1994 and July 2006 at our institution. Cardiac function was restored in 8 patients, who were weaned from LVAS after a mean of 5 months (Group R). Thirty-three patients remained on LVAS support for >1 year (Group N) because natural heart function did not show adequate improvement. We retrospectively evaluated the differences between these two groups. Group R was younger, and had a shorter duration of heart failure than Group N (23.4 vs 36.7 years and 13.3 vs 56.1 months, p < 0.01, respectively). Pathologic findings showed that the interstitial fibrosis score was lower in Group R (p < 0.01). Three months after LVAS insertion, B-type natriuretic peptide (BNP) and fractional shortening (FS) were more favorable (66.6 +/- 46 vs 264.5 +/- 170 pg/ml, p < 0.01, and 23 +/- 17.1 vs 12 +/- 9.1%, p < 0.05, respectively) in Group R. Furthermore, Group R received a higher dose of beta-blocker (15.4 +/- 8.4 vs 5.8 +/- 3.9 mg, p < 0.05).nnnCONCLUSIONSnYounger age, shorter history of heart failure, and less interstitial fibrosis were effective predictors of weaning from LVAS. Restoration of natural heart function was more rapid and more persistent in candidates for LVAS explantation, and presence of beta-blocker played a prominent role in improving cardiac function after LVAS implantation.

Genetic Variations and Haplotype Structures of the ABCB1 Gene in a Japanese Population: An Expanded Haplotype Block Covering the Distal Promoter Region, and Associated Ethnic Differences

As functional ABCB1 haplotypes were recently reported in the promoter region of the gene, we resequenced the ABCB1 distal promoter region, along with other regions (the enhancer and proximal promoter regions, and all 28 exons), in a total of 533 Japanese subjects. Linkage disequilibrium (LD) analysis based on 92 genetic variations revealed 4 LD blocks with the same make up as previously described (Blocks −1, 1, 2 and 3), except that Block 1 was expanded to include the distal promoter region, and that a new linkage between polymorphisms −1789G>A in the distal promoter region and IVS5 + 123A>G in intron 5 was identified. We re‐assigned Block 1 haplotypes, and added novel haplotypes to the other 3 blocks. The reported promoter haplotypes were further classified into several types according to tagging variations within Block 1 coding or intronic regions. Our current data reconfirm the haplotype profiles of the other three blocks, add more detailed information on functionally‐important haplotypes in Block 1 and 2 in the Japanese population, and identified differences in haplotype profiles between ethnic groups. Our updated analysis of ABCB1 haplotype blocks will assist pharmacogenetic and disease‐association studies carried out using Asian subjects.

Genetic Polymorphisms and Haplotypes of the Human Cardiac Sodium Channel α Subunit Gene (SCN5A) in Japanese and their Association with Arrhythmia

Genetic variations in cardiac ion channels have been implicated not only as the causes of inherited arrhythmic syndromes, but also as genetic risk factors for some acquired arrhythmias. To elucidate the potential roles of genetic polymorphisms of the α subunit of the voltage‐gated sodium channel type V (SCN5A) in cardiac rhythm disturbance, the entire SCN5A coding exons and their flanking introns were sequenced in 166 Japanese arrhythmic patients and 232 healthy controls. We detected 69 genetic variations, including 54 novel ones. Out of the 12 novel nonsynonymous single nucleotide polymorphisms (SNPs), p.Leu1988Arg was found at a frequency of 0.015. The other 11 SNPs were rare (0.001), with 6 found in arrhythmic patients and 5 in healthy controls. The frequency of a novel intronic SNP, c.703+130G>A, was significantly higher in the patients than in the controls, suggesting this SNP is associated with an unknown risk factor for arrhythmia. Following linkage disequilibrium analysis, the haplotype structure of SCN5A was inferred using high‐frequency SNPs. The frequency of the haplotype harbouring both p.Leu1988Arg and the common SNP p.His558Arg (haplotype GG) was significantly lower in the patients than in the controls. This finding suggests that this haplotype (GG) might have been positively selected in the controls because of its protective effect against arrhythmias. This study provides fundamental information necessary to elucidate the effect of genetic variations in SCN5A on channel function and cardiac rhythm in Japanese, and probably in the Asian population.

Drug interaction between tacrolimus and carbamazepine in a Japanese heart transplant recipient: a case report.

This article reports changes in tacrolimus (FK506) blood levels connected with carbamazepine (CBZ). A drug interaction between FK506 and CBZ was investigated in a woman, who was in her 40s, who underwent heart transplantation. Pharmacokinetic parameters were measured, including dose and trough blood levels (C(0)), area under the serum concentration-time curve from 0 to 12 hours (AUC(0-12h)), and apparent clearance of oral FK506 (CL/F) for FK506 alone (about 3 months before starting CBZ) and combined with CBZ (11 days and about 3 months after starting CBZ). FK506 C(0) levels were decreased within 7 days of CBZ treatment. FK506 dosing required a 1.3- to 1.4-fold increase to maintain adequate blood levels while taking 200 mg CBZ daily. The AUC(0-12h)/dose 11 days after CBZ treatment was about 50% of the value before CBZ, and was about 70% at 3 months after CBZ treatment. The CL/F at 11 days and about 3 months after starting CBZ treatment was about 2 times higher than before CBZ therapy. FK506 C(0) levels are decreased by CBZ treatment, and blood levels should be closely monitored.

4: Which factors predict the recovery of natural heart function after left ventricular assist system insertion

analysis were performed. Results: 15 pts requiring VAD support were studied. All pts demonstrated significantly improved Grade LV, LVDD, LVSD and mitral regurgitation after VAD. Six pts (responders) demonstrated significant improvements in c after VAD (Figure 1). There were no differences in lab, hemodynamic or echo variables between responders vs non-responders, pre or post-VAD. There was a greater improvement in c(14.2% vs 4.2%, p .005) and SR E (0.87 vs 0.31, p .025) in responders vs nonresponders. SR S, SR E and c correlated with an improvement in post-VAD LV grade in responders only ( r 0.86; p .025, r 0.89;p .016, r 0.81;p .047). Responders had improved systolic and SR despite a trend towards shorter mean duration of support (77.5 vs 126.8 days). Conclusions: This pilot study demonstrates the utility of SI in the objective assessment of myocardial function in pts with VAD. SI supplements conventional EF measurement and may be a useful technique to identify responders to VAD support. Further studies are needed to determine whether this technique can be applied clinically as a predictor of LV recovery.