Cusp overlap technique decreases paravalvular leakage in self-expandable transcatheter aortic valve replacement

The cusp overlap technique allows greater visual separation between the basal annular plane and the conduction system and decreases the permanent pacemaker implantation rate. We assessed the impact of the cusp overlap technique on conduction disturbance and paravalvular leakage after transcatheter aortic valve replacement. A total of 97 patients underwent transfemoral transcatheter aortic valve replacement with self-expandable valves at our institution from November 2018 to January 2023. The mean age of the patients was 85 years, and 23% were male. The patients were divided into two groups: the cusp overlap technique group and the non-cusp overlap technique group. We compared the clinical results between the two groups. The 30-day permanent pacemaker implantation rate was similar between the two groups (cusp overlap technique: 6.3% vs. non-cusp overlap technique: 10.2%, p = 0.48). The rate of new-onset conduction disturbance was slightly lower in the cusp overlap than non-cusp overlap technique group (18.8% vs. 34.7%, respectively; p = 0.08). The implanted valve function was similar between the two groups, but the rate of trivial or less paravalvular leakage (PVL) was significantly higher in the cusp overlap technique group on echocardiography (69% vs. 45%, p = 0.02). On multidetector computed tomography, the implantation depth at the membranous septum was significantly shorter in the cusp overlap technique group (2.0 ± 2.3 vs. 2.9 ± 1.5 mm, p = 0.02). The degree of canting was slightly smaller in the cusp overlap technique group (1.0 ± 2.2 vs. 1.7 ± 1.9 mm, p = 0.07). The relative risk of PVL equal to or greater than mild was 1.76 times higher for valve implantation without the cusp overlap technique (adjusted odds ratio, 3.74; 95% confidence interval, 1.45-9.69; p < 0.01). Transcatheter aortic valve replacement using the cusp overlap technique is associated with an optimized implantation depth, leading to fewer conduction disturbances. Optimal deployment may also maximize the radial force of self-expanding valves to reduce paravalvular leakage.

Optical film-thinning of few-layer graphene epitaxially grown on 4H-SiC(0001) surface : Robustness of monolayer-graphene against the photoexcitation

As the properties of graphene films depend on their stacked atomic layers, their thickness should be accurately controlled to improve their specific properties. However, by existing methods, controlling the homogeneity of graphene films at the atomic level remains difficult. In this work, photo-stimulated structural modifications of few-layer graphene epitaxially grown on 4H-SiC(0001) were studied using Raman scattering spectroscopy and core-level photoemission spectroscopy. Iterative excitation with laser pulses (800nm, 100fs, p-polarized, 250mJ/cm2) changed the graphene-related 2D Raman line, which is composed of three components characterized by their different responses upon photoexcitation: two components decaying at fast and slow rates, and a component highly resistant to excitation. Core-level photoemission spectroscopy revealed that the observed decay of the 2D line was associated with the elimination of carbon atoms from the graphene layers, finally leaving the robust thin film of single-layer graphene by prolonged excitation. Therefore, this work clearly demonstrates the thickness-dependent structural stability of graphene to optical excitation and opens a promising new method for thinning graphene. An underlying mechanism for the photo-stimulated modifications was also proposed.

Thickness dependent band structure of-bismuthene grown on epitaxial graphene

Along with the great interest in two-dimensional elemental materials that has emerged in recent years, atomically thin layers of bismuth have attracted attention due to physical properties on account of a strong spin-orbit coupling. Thickness dependent electronic band structure must be explored over the whole Brillouin zone in order to further explore their topological electronic properties. The anisotropic band structures along zig-zag and armchair directions of α-bismuthene (α-Bi) were resolved using the two-dimensional mapping of angle-resolved photoemission spectra. An increase in the number of layers from 1- to 2-bilayers (BLs) shifts the top of a hole band onΓ¯-X¯1line to high wavenumber regions. Subsequently, an electron pocket onΓ¯-X¯1line and a hole pocket centred atΓ¯point appears in the 3 BL α-Bi. Gapless Dirac-cone features with a large anisotropy were clearly resolved onX¯2point in the 1-BL and 2-BL α-Bi, which can be attributed to the strong spin-orbit coupling and protection by the nonsymmorphic symmetry of the α-Bi lattice.

Genetic variants in combination with early partial improvement as a clinical utility predictor of treatment outcome in major depressive disorder: the result of two pooled RCTs

Pharmacogenetics may allow for a personalized treatment, but a combination with clinical variables may further enhance prediction. In particular, in the present paper, we investigated early partial improvement (EPI) defined as 20% or more improvement by rating scales 2  weeks after treatment, in combination with selected gene variants as a predictor of treatment outcome in patients with major depressive disorder. Two randomized controlled trials with 168 Japanese depressed patients were used. A stepwise multiple linear regression model with HAM-D score change at week 6 as the dependent variable and genotypes, EPI, baseline HAM-D score, age and sex as independent variables was performed in paroxetine, fluvoxamine and milnacipran, respectively, to estimate the prediction of HAM-D change at week 6. In the paroxetine sample, only EPI (P<0.001) was significantly associated with HAM-D change (n=81, R(2)=0.25, P<0.001). In the fluvoxamine sample, 5-HTTLPR La/Lg, S (P=0.029), FGF2 rs1449683C/T (P=0.013) and EPI (P=0.003) were associated with HAM-D change (n=42, R(2)=0.43, P<0.001). In the milnacipran sample, HTR-1A-1019C/G (P=0.001), ADRA2A-1297C/G (P=0.028) and EPI (P<0.001) were associated with outcome (n=45, R(2)=0.71, P<0.001). EPI in combination with genetic variants could be a useful predictor of treatment outcome and could strengthen the practical use of pharmacogenetic data in clinical practice.

Topological phase transitions driven by magnetic phase transitions in Fe(x)Bi2Te3 (0≤x≤0.1) single crystals

We propose a phase diagram for Fe(x)Bi2Te3 (0≤x≤0.1) single crystals, which belong to a class of magnetically bulk-doped topological insulators. The evolution of magnetic correlations from ferromagnetic to antiferromagnetic gives rise to topological phase transitions, where the paramagnetic topological insulator of Bi2Te3 turns into a band insulator with ferromagnetic-cluster glassy behavior around x∼0.025, and it further evolves to a topological insulator with valence-bond glassy behavior, which spans over the region from x∼0.03 up to x∼0.1. This phase diagram is verified by measuring magnetization, magnetotransport, and angle-resolved photoemission spectra with theoretical discussions.

Photoemission study on the valence band of a β-FeSi2 thin film using synchrotron radiation

Resonant and constant-initial state photoemission spectroscopies using synchrotron radiation were applied to investigate the valence-band electronic structure of a semi-conducting β-type iron-disilicide (β-FeSi(2)) thin film. The results clearly indicated that the component elements, iron (Fe) and silicon (Si), contribute differently to the valence band features; the Fe 3d orbitals mainly concentrate in the top region of the valence band while the Si 3s and 3p orbitals spread over the wide region of the valence band. The β-FeSi(2) thin film showed a typical p-type semi-conducting nature with a work function of 4.78 eV. The β-FeSi(2) film showed the Fe M(1)VV Auger lines around the kinetic energy of 88 eV. It would be expected from these observations that there exist strong interactions between iron and silicon atoms in the β-FeSi(2) film resulting in orbital mixing and band formation.

Microwave-assisted autohydrolysis of Prunus mume stone for extraction of polysaccharides and phenolic compounds

Stone of Prunus mume (P. mume) is a by-product of pickled P. mume industry. Stones of native and pickled P. mume, mainly composed of holocellulose (83.8 +/- 1.8% and 65.1 +/- 0.3%, respectively) and acid-insoluble lignin (25.3 +/- 2.2% and 30.6 +/- 0.9%, respectively), were autohydrolyzed by microwave heating to extract polysaccharides and phenolic compounds. By heating at 200 to 230 degrees C, 48.0% to 60.8% of polysaccharide and 84.1% to 97.9% of phenolic compound were extracted in water along with partial degradation of hemicelluloses and lignin. The extracted liquors showed antioxidant activity against hydroxyl radical and DPPH radical originated from phenolic compounds. The pickled P. mume stone showed higher autohydrolyzability and microwave absorption capacity than the native stone due to absorbed salts and acids during pickling in fruit juice of P. mume with external addition of sodium chloride. Pickling process in salty and weak acidic juice seemed to be a kind of pretreatment for softening the stones prior to autohydrolysis induced by microwave heating.

Long-term safety and efficacy of tocilizumab, an anti-IL-6 receptor monoclonal antibody, in monotherapy, in patients with rheumatoid arthritis (the STREAM study): evidence of safety and efficacy in a 5-year extension study

OBJECTIVES

To evaluate the safety and efficacy of 5-year, long-term tocilizumab monotherapy for patients with rheumatoid arthritis.

METHODS

In an open-label, long-term extension trial following an initial 3-month randomised phase II trial, 143 of the 163 patients who participated in the initial blinded study received tocilizumab monotherapy (8 mg/kg) every 4 weeks. Concomitant therapy with non-steroidal anti-inflammatory drugs and/or oral prednisolone (10 mg daily maximum) was permitted. All patients were evaluated with American College of Rheumatology (ACR) improvement criteria, disease activity score (DAS) in 28 joints, and the European League Against Rheumatism response, as well as for safety issues.

RESULTS

143 patients were enrolled in the open-label, long-term extension trial and 94 (66%) patients had completed 5 years as of March 2007. 32 patients (22%) withdrew from the study due to adverse events and one patient (0.7%) due to unsatisfactory response. 14 patients withdrew because of the patient's request or other reasons. The serious adverse event rate was 27.5 events per 100 patient-years, with 5.7 serious infections per 100 patient-years, based on a total tocilizumab exposure of 612 patient-years. Of the 88 patients receiving corticosteroids at baseline, 78 (88.6%) were able to decrease their corticosteroid dose and 28 (31.8%) discontinued corticosteroids. At 5 years, 79/94 (84.0%), 65/94 (69.1%) and 41/94 (43.6%) of the patients achieved ACR20, ACR50, and ACR70 improvement criteria, respectively. Remission defined as DAS28 less than 2.6 was achieved in 52/94 (55.3%) of the patients.

CONCLUSION

In this 5-year extension study, tocilizumab demonstrated sustained long-term efficacy and a generally good safety profile.

Pharmacokinetics/genotype associations for major cytochrome P450 enzymes in native and first- and third-generation Japanese populations: comparison with Korean, Chinese, and Caucasian populations

Application of foreign clinical data across geographic regions can accelerate drug development. Drug disposition can be variable, and identification of factors influencing responsible pharmacokinetic/pharmacogenomic approaches could facilitate the universal application of foreign data and reduce the total amount of phase III clinical trials evaluating risks in different populations. Our objective was to establish and compare genotype (major cytochrome P450 (CYP) enzymes)/phenotype associations for Japanese (native and first- and third-generation Japanese living abroad), Caucasian, Chinese, and Korean populations using a standard drug panel. The mean metabolic ratios (MRs) for the four ethnic groups were similar except for a lower activity of CYP2D6 in Caucasians and CYP2C19 in Asians. Genotype, not ethnicity, impacted the MR for CYP2C9, CYP2C19, and CYP2D6; neither affected CYP1A2, CYP2E1, and CYP3A4/5 activities. We conclude that equivalent plasma drug concentrations and metabolic profiles can be expected for native Japanese, first- and third-generation Japanese, Koreans, and Chinese for compounds handled through these six CYP enzymes.

Polymorphisms of norepinephrine transporter and adrenergic receptor alpha1D are associated with the response to beta-blockers in dilated cardiomyopathy

Recent clinical trials have clearly demonstrated that the administration with beta-blockers decreases the mortality in the patients with chronic heart failure (CHF). However, significant heterogeneity exists in the effectiveness of beta-blockers among individual cases. We focused on 39 polymorphisms in 16 genes related to adrenergic system and investigated their association with the response to beta-blockers among 80 patients with CHF owing to idiopathic dilated cardiomyopathy. The polymorphisms of NET T-182C (P=0.019), ADRA1D T1848A (P=0.023) and ADRA1D A1905G (P=0.029) were associated with the improvement of left ventricular fractional shortening (LVFS) by beta-blockers. Furthermore, combined genotype analysis of NET T-182C and ADRA1D T1848A revealed a significant difference in LVFS improvement among genotype groups (P=0.011). These results suggest that NET (T-182C) and ADRA1D (T1848A and A1905G) polymorphisms are predictive markers of the response to beta-blockers. Genotyping of these polymorphisms may provide clinical insights into an individual difference in the response to the beta-blocker therapy in CHF.

Infrared absorption change in single-walled carbon nanotubes observed by combination spectroscopy of synchrotron radiation and laser

The Drude tail due to photo-excited carriers in single-walled carbon nanotubes (SWNTs) has been observed in the mid-infrared region by using combination spectroscopy of synchrotron radiation and Ti:sapphire laser. It is found that the density of photo-excited carriers increases as the sample temperature is raised from 12 to 300 K, and their lifetime is of the order of minutes at 300 K. These facts suggest that the movement of photo-excited carriers is largely affected by some extrinsic defect, thus resulting in the long-lasting Drude reflection in SWNTs.

Angiogenic and antifibrotic actions of hepatocyte growth factor improve cardiac dysfunction in porcine ischemic cardiomyopathy

Impairment of cardiac function in ischemic cardiomyopathy has been postulated to be due to the decrease in blood flow and increase in collagen synthesis. Therefore, an approach to alter them directly by means of a growth factor may open up a new therapeutic concept in ischemic cardiomyopathy. From this viewpoint, hepatocyte growth factor (HGF) is a unique growth factor with angiogenic and antifibrotic effects. Thus, we examined the feasibility of gene therapy using HGF plasmid DNA for ischemic cardiomyopathy. Human HGF plasmid DNA at a dose of 0.4 or 4 mg was injected into ischemic myocardium of pigs induced by ameroid constrictor with the NOGA system. At 1 month after injection, the ischemic area was significantly reduced in the HGF group, accompanied by a significant increase in capillary density and regional myocardial perfusion in the ischemic area (P<0.01). In contrast, a significant decrease in fibrotic area was observed in the HGF group, associated with a significant decrease in collagen I, III and TGF-beta synthesis as compared to the control group (P<0.01). Consistently, cardiac function was significantly improved in the 4 mg HGF group as compared to the control group (P<0.05). Overall, the present in vivo experiments demonstrated that intramyocardial injection of human HGF plasmid DNA in ischemic cardiomyopathy resulted in a significant improvement in cardiac function through an increase in blood flow and decrease in fibrosis. These favorable outcomes suggest potential utility to treat patients with ischemic heart disease using HGF gene transfer. Currently, a phase I study using human HGF plasmid DNA is ongoing to test the validity of this concept.

CYP2A6 polymorphisms are associated with nicotine dependence and influence withdrawal symptoms in smoking cessation

CYP2A6 is the main enzyme that catalyzes nicotine into cotinine. Interindividual differences in nicotine metabolism result at least partially from polymorphic variation of CYP2A6 gene. In this study, we evaluated the influence of CYP2A6 polymorphisms on clinical phenotypes of smoking, such as smoking habit and withdrawal symptoms. Japanese smokers (n = 107) were genotyped for CYP2A6*1, *4 and *9. Consistent with the previous reports, CYP2A6 genotypes have a tendency to correlate with the number of cigarettes per day and with daily intake of nicotine. Interestingly, CYP2A6 high-activity group (CYP2A6*1/*1, *1/*9, *1/*4, *9/*9) smoked the first cigarette of the day earlier than low-activity group (CYP2A6*4/*9, *4/*4), indicating more remarkable nicotine dependence. Furthermore, nicotine withdrawal symptoms were more serious in smoking cessation in CYP2A6 high-activity group. Collectively, CYP2A6 genotypes are related with nicotine dependence, influencing smoking habits and withdrawal symptoms in quitting smoking. It is proposed that individualized smoking cessation program could be designed based on CYP2A6 genotypes.

Two-photon spectroscopy of core excitons in barium fluoride using synchrotron radiation and laser light

We have conducted two-photon spectroscopy of core excitons in BaF(2). Synchrotron radiation and laser light were used for 5p core-electron excitation and Auger-free luminescence was detected as the signal. Two-photon excitation enables access to f and p orbitals that cannot be reached by one-photon excitation of electrons in p orbitals. It has been found that the spin-orbit splittings of 4f and 6p states of the Ba ion in BaF(2) are 0.7 +/- 0.1 and 1.4 +/- 0.1 eV, respectively.

Protective effect of taurine on the detachment of cultured cardiac fibroblasts from the substratum induced by calcium depletion

Removal of Ca2+ from the incubation medium of cultured rat cardiac fibroblasts causes cellular morphological changes, such as the formation of blebs, the ballooning of the cell membrane and the detachment from the culture dish. A 24 hr preincubation with 20 mM taurine blocked the Ca2+ depletion-induced detachment of the cardiac fibroblasts. However, taurine treatment did not prevent other morphological changes induced by Ca2+ depletion. The data suggest that taurine plays an important role in cell adhesion in the heart.

CYP3A5 genotype did not impact on nifedipine disposition in healthy volunteers

CYP3A5 expression is regulated by single-nucleotide polymorphisms (SNPs). The CYP3A5 genotype might contribute to a marked interindividual variation in CYP3A-mediated metabolism of drugs. Nifedipine is a typical substrate of CYP3A4 and CYP3A5 in vitro. The aim of this study was to elucidate the influence of the CYP3A5 genotype on nifedipine disposition in healthy subjects. A single capsule containing 10 mg of nifedipine was administered to 16 healthy male Japanese subjects (eight subjects: CYP3A5(*)1/(*)3; eight subjects: CYP3A5(*)3/(*)3). Blood samples were collected to analyze the pharmacokinetics of serum nifedipine and nitropyridine metabolite (M-I). The area under the plasma concentration-time curve (AUC), the peak plasma concentration (C(max)) and the terminal half-life (t(1/2)) of nifedipine, and the ratio of the nifedipine AUC to M-I AUC showed large intragroup variations, but no significant differences between the two genotypes. Based on the present findings, the functional relevance of CYP3A5 polymorphism should be re-evaluated in clinical trials.

The association of Pro12Ala polymorphism in PPARgamma2 with lower carotid artery IMT in Japanese

In this study, the association of the Pro12Ala peroxisome proliferator-activated receptor gamma2 (PPARgamma2) polymorphism with atherosclerosis was examined in a Japanese Type 2 diabetic population. PPARgamma has been identified as a key regulator of adipogenesis. Recently, some studies reported that the Pro12Ala polymorphism was associated with resistance to Type 2 diabetes. It is well-known that Type 2 diabetes is closely related with disorder of lipid metabolism as well as impaired glucose homeostasis, resulting in atherosclerosis. We aimed to evaluate the association between carriers of the Pro12Ala PPARgamma2 mutation and clinical profiles concerning atherosclerosis besides plasma glucose and lipid concentrations. Screening for the mutation was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method among 154 Type 2 diabetic patients. The homozygotes of the Pro12 allele were 143 (93%), the heterozygotes of the Pro12 and Ala12 allele were 11 (7%) and the homozygote of the Ala12 allele was not detected. The group with the Ala12 allele had a significantly lower value of carotid artery intima-media thickness (IMT) than that without it, although there was no difference between two groups in sex, age or other clinical variables we examined. The Pro12Ala PPARgamma2 polymorphism may be associated with carotid artery IMT values in Type 2 diabetes mellitus.

In vitro inhibitory effects of Kampo medicines on metabolic reactions catalyzed by human liver microsomes

BACKGROUND

Although it is well known that drug-drug interactions may lead to toxicity and therapeutic failure, little is known about the incidence and consequences of herb-drug interactions in patients receiving Kampo medicines.

METHODS

We evaluated the frequency of the combined use of Kampo medicines and Western drugs at Osaka University Hospital, and investigated the effects of these formulae on the metabolic activity of different cytochrome P450 (CYP) isoforms using pooled microsomes obtained from human liver.

RESULTS

Twenty-two Kampo formulae were used together with 40 Western drugs catalyzed by the CYP isoforms CYP3A4, CYP2C9, CYP2D6 and CYP1A2. Among the Kampo medicines, HOCHUEKKI-TO, SHOSAIKO-TO, NINJINYOUEI-TO, SAIREI-TO and KAKKON-TO were most frequently used during the study period (1996-2000). These were co-administered with 11 categories of drugs, which are substrates for CYP3A4. HOCHUEKKI-TO and SAIREI-TO were competitive inhibitors of CYP3A4 with Ki values of 0.65 and 0.1 mg/mL, respectively. HOCHUEKKI-TO, SHOSAIKO-TO and SAIREI-TO inhibited the metabolic activities of CYP2C9, but had no effect on CYP2D6. HOCHUEKKI-TO and SAIREI-TO exhibited non-competitive inhibition of the metabolic activity of CYP2C9 with a similar Ki value (0.7-0.8 mg/mL). SAIRE-TO (0.25 mg/mL) was a potent inhibitor of CYP1A2 (inhibition > 68%).

CONCLUSIONS

Frequently used Kampo medicines may interact with Western drugs, which are substrates for CYP3A4, CYP2C9 and CYP1A2. Their co-administration should be undertaken with care.

Effect of ischemia, calcium depletion and repletion, acidosis and hypoxia on cellular taurine content

Occlusion of the left main coronary artery led to a time-dependent release of taurine from the heart. Upon reperfusion, there was a second phase of taurine release, which exceeded the amount of taurine that exited the heart during the 45 min ischemic insult. To obtain information on the mechanism underlying the release of taurine, three variables were examined, acidosis, hypoxia and calcium overload. It was found that large amounts of taurine also leave the cell during the calcium paradox, a condition induced by perfusing the heart with calcium containing buffer following a period of calcium free perfusion. However, little taurine effluxes the hearts exposed to buffer whose pH was lowered to 6.6. Isolated neonatal cardiomyocytes subjected to chemical hypoxia also lost large amounts of taurine. However, the amount of taurine leaving the cells appeared to be correlated with the intracellular sodium concentration, [Na(+)](i). The data suggest that taurine efflux is regulated by [Na(+)](i) and cellular osmolality, but not by cellular pH.

CYP2C9*3 influences the metabolism and the drug-interaction of candesartan in vitro

Candesartan cilexetil is an angiotensin II receptor antagonist, and candesartan, its active metabolite, is metabolized by CYP2C9. However, the effect of CYP2C9*3 on candesartan metabolism is not established. We characterized the kinetics of candesartan by CYP2C9*1/*1 and CYP2C9*1/*3 in human liver microsomes. The difference between the two was not significant. Subsequently, CYP2C9*1 and CYP2C9*3 (Leu359) were expressed in yeast, and the kinetics of candesartan were determined. The wild-type showed the lower Km (345 vs 439 microM; 3/4) and higher Vmax/Km (1/3) than the Leu359 variant. Also, we investigated potential interaction between candesartan and warfarin with both the wild-type and the Leu359 variant. Candesartan had no effect on S-warfarin 7-hydroxylation. In contrast, S-warfarin inhibited candesartan metabolism by the wild-type (K = 17microM) greater than by the Leu359 variant (Ki = 36 microM). These findings suggest that CYP2C9*3 may change not only the metabolic activity but also the inhibitory susceptibility compared with CYP2C9*1.

Protective effect of Salvia miltiorrhiza on angiotensin II-induced hypertrophic responses in neonatal rat cardiac cells

The effect of the root of Salvia miltiorrhiza (SM) on angiotensin II (Ang II)-induced hypertrophic responses was examined in cultured neonatal rat cardiac cells (cardiomyocytes and non-cardiomyocytes). The methanol eluate fraction (SM2) of the water extract and the ethyl acetate-insoluble fraction (SM3) and its soluble fraction (SM4) partitioned from the methanol extract were prepared. Treatment with SM4 (5-80 microg/ml), not SM2 and SM3, for 24 h produced dose-dependent cytotoxicity against cardiac cells relative to the reduction in viability and the morphological injury of cardiomyocytes. SM2 or SM3 in the absence of Ang II affected neither hyperplastic nor hypertrophic growth of both cell types. However, SM3 (40 microg/ml) attenuated the positive chronotropic responsiveness of cardiomyocytes to Ang II (1 nM) stimulation, whereas Ang II-induced increase in non-cardiomyocyte number was decreased only by SM2 (40 microg/ml) treatment. Furthermore, SM3 suppressed Ang II-induced enlargement of cell size by preceding Ang II-induced induction of immediate early response gene (c-jun) expression in cardiomyocytes, while SM2 decreased Ang II-induced DNA synthesis in non-cardiomyocytes. Moreover, three phenolic compounds and tanshinone IIA that differed quantitatively among three SM fractions were identified by reverse-phase high performance liquid chromatography. Thus, the present findings indicate that the root of SM is an effective inhibitor of Ang II action and has a plural effective constituent, which possess different pharmacological activities on Ang II-induced hypertrophy and hyperplasia in cultured neonatal rat cardiac cells.

Impact of pre-stent plaque debulking for chronic coronary total occlusions on restenosis reduction

BACKGROUND

While stenting improves the long-term angiographic outcomes of successfully recanalized chronic coronary total occlusions (CTO), the restenosis rate still remains high. The massive plaque burden in CTO is considered to be one of the causes of in-stent restenosis.

METHODS

We examined the pre-stent plaque debulking strategy with high-speed rotational atherectomy (RA) for 50 CTO (Thrombolysis in Myocardial Infarction flow grade 0; estimated occlusive duration, 3 months). Angiographic follow-up results were compared to those of 120 consecutive CTO recanalized with primary stenting in which RA could be indicated retrospectively. Angiographic restenosis was defined as diameter stenosis > 50% at 6-month follow-up.

RESULTS

RA could be performed safely in all lesions without any major complications. Adjunctive ballooning and stenting could be performed without high-pressure dilatation (8.4 +/- 1.7 atmospheres). Follow-up angiography was performed in 48 lesions 184 +/- 61 days after the procedure. There were no significant differences in baseline characteristics between the two groups; however, the implanted stent type was different. Quantitative coronary angiography revealed that diameter stenosis was smaller at follow-up (36.2 +/- 20.0% versus 52.2 +/- 26.7%; p = 0.0003) as well as post-procedure (7.8 +/- 11.5% versus 17.8 +/- 13.6%; p < 0.0001) compared with the control group. Angiographic restenosis was also significantly reduced (29.2% versus 52.5%; p = 0.0061).

CONCLUSIONS

RA is a safe procedure for plaque debulking of CTO in selected cases. Plaque debulking of CTO facilitates subsequent stent expansion and may reduce the restenosis rate.

Role of osmoregulation in the actions of taurine

Taurine regulates an unusual number of biological phenomena, including heart rhythm, contractile function, blood pressure, platelet aggregation, neuronal excitability, body temperature, learning, motor behavior, food consumption, eye sight, sperm motility, cell proliferation and viability, energy metabolism and bile acid synthesis. Many of these actions are associated with alterations in either ion transport or protein phosphorylation. Although the effects on ion transport have been attributed to changes in membrane structure, they could be equally affected by a change in the activity of the affected transporters. Three common ways of altering transporter activity is enhanced expression, changes in the phosphorylation status of the protein and cytoskeletal changes. Interestingly, all three events are altered by osmotic stress. Since taurine is a key organic osmolyte in most cells, the possibility that the effects of taurine on ion transport could be related to its osmoregulatory activity was considered. This was accomplished by comparing the effects of taurine, cell swelling and cell shrinkage on the activities of key ion channels and ion transporters. The review also compares the phosphorylation cascades initiated by osmotic stress with some of the phosphorylation events triggered by taurine depletion or treatment. The data reveal that certain actions of taurine are probably caused by the activation of osmotic-linked signaling pathways. Nonetheless, some of the actions of taurine are unique and appear to be correlated with its membrane modulating and phosphorylation regulating activities.

Cellular characterization of an in-vitro cell culture model of seal-induced cardiac ischaemia

The lack of a well-characterized in-vitro cell culture model of load-induced cardiac ischaemia has hampered investigations into the mechanism of ischemic injury. We therefore developed a new in-vitro model of cardiac ischaemia that mimics distinct features of ischaemic injury. Neonatal rat heart cells were cultured in a sealed flask for 24-72 h. In this environment, the cells were exposed to stresses of hypoxia, acidosis and stagnant incubation medium. The pO2 and pH of the medium gradually decreased during the ischaemic insult and ultimately fell to a level of 14 mmHg and pH 6.8, respectively. The model triggered severe cell injury, including morphological degeneration, CPK release, beating impairment and ATP depletion. Apoptosis occurred in some cardiomyocytes as early as 24 h after onset of seal-induced ischaemia. This was evidenced by positive nuclear staining using Hoechst 33258 and by the induction of caspase-3 mRNA. By 72 h, internucleosomal DNA fragmentation was observed in 45% of the myocytes; however, a non-myocyte preparation subjected to the same ischaemic insult exhibited no evidence of DNA fragmentation. These results demonstrate that neonatal cardiomyocytes subjected to the new simulated ischaemia model exhibit several similarities to cardiac ischaemia, including the simultaneous appearance of necrosis, breakdown of cellular ATP, beating cessation and apoptosis. The new model should prove useful in unravelling the molecular alterations underlying ischaemic injury and myocardial apoptosis.

Interaction between the actions of taurine and angiotensin II

The amino acid, taurine, is an important nutrient found in very high concentration in excitable tissue. Cellular depletion of taurine has been linked to developmental defects, retinal damage, immunodeficiency, impaired cellular growth and the development of a cardiomyopathy. These findings have encouraged the use of taurine in infant formula, nutritional supplements and energy promoting drinks. Nonetheless, the use of taurine as a drug to treat specific diseases has been limited. One disease that responds favorably to taurine therapy is congestive heart failure. In this review, we discuss three mechanisms that might underlie the beneficial effect of taurine in heart failure. First, taurine promotes natriuresis and diuresis, presumably through its osmoregulatory activity in the kidney, its modulation of atrial natriuretic factor secretion and its putative regulation of vasopressin release. However, it remains to be determined whether taurine treatment promotes salt and water excretion in humans with heart failure. Second, taurine mediates a modest positive inotropic effect by regulating [Na+]i and Na+/Ca2+ exchanger flux. Although this effect of taurine has not been examined in human tissue, it is significant that it bypasses the major calcium transport defects found in the failing human heart. Third, taurine attenuates the actions of angiotensin II on Ca2+ transport, protein synthesis and angiotensin II signaling. Through this mechanism taurine would be expected to minimize many of the adverse actions of angiotensin II, including the induction of cardiac hypertrophy, volume overload and myocardial remodeling. Since the ACE inhibitors are the mainstay in the treatment of congestive heart failure, this action of taurine is probably very important.

Taurine attenuates hypertrophy induced by angiotensin II in cultured neonatal rat cardiac myocytes

The effect of taurine on angiotensin II-induced changes in cell morphology and biochemistry of the cultured neonatal cardiomyocyte was examined. Angiotensin II (1-100 nM) alone caused a slow increase in the surface area of the myocyte accompanied by an induction of the expression of atrial natriuretic peptide (ANP) and an upregulation of transforming growth factor beta(1) gene (TGF-beta(1)). The signaling pathway of angiotensin II (1-100 nM) was found to proceed through protein kinase C and the rapid activation of mitogen-activated protein (MAP) kinases. Pretreatment of the myocyte with taurine (20 mM) in the absence of angiotensin II had no visible effect on cell size or growth rate. However, the cells that were pretreated with taurine (20 mM) for 24 h exhibited reduced responsiveness to angiotensin II (100 nM) relative to surface cell area enlargement and the upregulation of the late and growth factor genes(ANP, TGF-beta(1)). Angiotensin II-mediated activation of the MAP kinases (extracellular signal-regulated protein kinase 1/2: ERK1/2) was not blocked by taurine. Taurine reduced the phosphorylation of a 29-kDa protein, a reaction which was enhanced by angiotensin II and appears to involve protein kinase C step. The results indicate that taurine is an effective inhibitor of certain aspects of angiotensin II action.

Specific determination of urinary 6beta-hydroxycortisol and cortisol by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

The urinary 6beta-hydroxycortisol to cortisol ratio is believed to be a noninvasive index of cytochrome P450 3A activity. For precise assessment of the ratio in human urine, we have developed a reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry method. The selective method was accurate and reproducible with intra- and inter-day precision of variation coefficients of less than 8%. The 6beta-hydroxycortisol to cortisol ratio ranged from 3.0 to 12.4 in healthy Japanese 24-h urine. With the recent popularization of LC-MS, our LC-MS method will be advantageous to detect human in vivo CYP3A activity for clinical investigation and routine measurement in various laboratories.

The decreased in vivo clearance of CYP2D6 substrates by CYP2D6*10 might be caused not only by the low-expression but also by low affinity of CYP2D6

CYP2D6 exhibits genetic polymorphism with interindividual differences in metabolic activity. We have found a significant influence on the pharmacokinetics of venlafaxine by the CYP2D6*10 allele in a Japanese population. CYP2D6.10, which is translated from CYP2D6*10, has two amino acid substitutions: Pro34 --> Ser and Ser486 --> Thr. In this study, CYP2D6.10 was expressed in Saccharomyces cerevisiae and its catalytic activity for CYP2D6 substrates was investigated. The CYP2D6*10B- and *10C-associated cDNA were isolated from human lymphocyte genotyped as CYP2D6*10. In addition, three forms of CYP2D6, Pro34/Thr486 (PT), Ser34/Ser486 (SS), and Pro34/Ser486 (wild type, CYP2D6.1), were constructed by PCR-site mutagenesis to clarify the effects of the two amino-acid substitutions. The expression of CYP2D6 protein was confirmed by immunoblotting using CYP2D antibody. The absorbance at 450 nm was measured by CO-reduced difference spectra from five all microsome preparations. The CYP2D6 forms with Pro34 --> Ser amino acid substitution were at a lower expression than CYP2D6.1 from the findings of immunoblotting and spectral analysis. The apparent K(m) values of CYP2D6.1, CYP2D6.10A, and CYP2D6.10C were 1.7, 8.5, and 49.7 microM, respectively, for bufuralol 1'-hydroxylation, and 9.0, 51.9, and 117.4 microM, respectively, for venlafaxine O-demethylation, respectively. The V(max) values were not significantly different among the three variants. These findings suggest that the decreased in vivo clearance by CYP2D6*10 was caused not only by low expression of but also the increased K(m) value of CYP2D6.

Distribution and properties of endo-beta-1,4-glucanase from a lower termite, Coptotermes formosanus (Shiraki)

A multi-enzyme distribution of endo-beta-1,4-glucanase activity was found in the digestive system of a worker caste of the lower termite Coptotermes formosanus (Shiraki) by zymogram analysis. Its distribution analysis demonstrated that about 80% of this activity was localized in salivary glands from where only one component (EG-E) was secreted into the digestive tract. EG-E was isolated by a combination of chromatographic and electrophoretic techniques. Its molecular mass, optimal pH and temperature, isoelectric point, and Km were 48 kDa, 6.0, 50 degrees C, 4.2, and 3.8 (mg/ml on carboxymethylcellulose), respectively. EG-E hydrolyzed cellooligosaccharides with a degree of polymerization of 4 and larger, and had low activity on crystalline cellulose. Main reaction products from low molecular weight cellulose were cellobiose and cellotriose. The N-terminal amino acid sequence of EG-E has similarity with fungal endo-beta-1,4-glucanases and cellobiohydrolases of the glycosyl hydrolase family 7 rather than the other insect endo-beta-1,4-glucanases of family 9.

The impact of the CYP2D6 and CYP2C19 genotypes on venlafaxine pharmacokinetics in a Japanese population

OBJECTIVE

The cytochrome P450 isozymes CYP2D6 and CYP2C19 exhibit genetic polymorphism in human, including a marked interethnic difference. As the functional status of the isozymes CYP2D6 and CYP2C19 have an impact on the pharmacokinetics of some antidepressants, we investigated whether the disposition of venlafaxine was affected by the CYP2D6 and CYP2C19 genotypes.

METHODS

Twenty-eight adult Japanese men in good health participated in this study. Genomic DNA was isolated from peripheral lymphocytes, and the CYP2D6 genotype was determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and XbaI-RFLP analysis. Subjects were categorized into the following four groups: group 1 CYP2D6*10/*10; group 2 CYP2D6*1/*10 and *2/*10; group 3 CYP2D6*1/*1, *1/*2 and *2/*2; and group 4 the other genotypes. Two defective CYP2C19 alleles (CYP2C19*2 and CYP2C19*3) were identified by means of PCR-RFLP analysis. Venlafaxine was administered orally following an overnight fast. Plasma concentrations of venlafaxine and O-desmethylvenlafaxine were monitored using high-performance liquid chromatography up to 24 h.

RESULTS

The peak plasma concentration and values of area under the concentration-time curve up to 24 h for venlafaxine were 298% and 453% higher for group 1 than group 3, and 91% and 120% higher for group 2 than for group 3, respectively. The homozygote for two defective alleles of CYP2C19 showed a higher concentration of venlafaxine within group 1 and group 2.

CONCLUSION

The CYP2D6*10 allele and two CYP2C19 defective alleles, common in an Asian population, are the most likely genetic factors to use in determining interindividual differences in the pharmacokinetics of venlafaxine, although the results with respect to CYP2C19 are preliminary because of the few subjects used.

Slow N-acetyltransferase 2 genotype affects the incidence of isoniazid and rifampicin-induced hepatotoxicity

SETTING

Japanese in-patients with pulmonary tuberculosis and normal liver function receiving treatment with isoniazid and rifampicin (INH + RMP).

OBJECTIVE

To elucidate the relationship between N-acetyltransferase 2 (NAT2) genotype and the incidence of isoniazid + rifampicin-induced hepatotoxicity.

DESIGN

Prospective study. After NAT2* genotyping, 77 patients were classified into three groups according to their NAT2* genotypes: rapid-type (a homozygote of NAT2*4), intermediate-type (a heterozygote of NAT2*4 and mutant alleles) and slow-type (a combination of mutant alleles). Their biochemical profiles of liver function test were investigated for 3 months to assess the development of serum aminotransferase elevation.

RESULT

Of the 77 patients, 18.2% developed adverse hepatic reaction within the first month of INH + RMP treatment. A significant association was observed between hepatotoxicity and NAT2* genotype: compared with rapid-type, the relative risk was 4.0 (95% CI 1.94-6.06) for intermediate-type and 28.0 (95%CI 26.0-30.0) for slow-type. Especially in slow-type, the incidence of hepatotoxicity and serum aminotransferase elevation was significantly higher than in the other two types.

CONCLUSION

Slow NAT2* genotype significantly affected the development of INH + RMP-induced hepatotoxicity. This suggests the possibility that NAT2* genotyping prior to medication may be useful in evaluating patients with high risk for INH + RMP-induced hepatotoxicity.

Circadian variation of the urinary 6beta-hydroxycortisol to cortisol ratio that would reflect hepatic CYP3A activity

OBJECTIVES

Chronopharmacokinetics of drugs metabolized by cytochrome P450 3A (CYP3A) has been reported recently; however, little is studied on intra-individual circadian variation in CYP3A activity in human. The aim of this study was to assess the intra-individual diurnal variation and day-to-day variation of the urinary 6beta-hydroxycortisol to cortisol ratio, a noninvasive index of human CYP3A activity.

METHODS

Urine samples from ten healthy Japanese men were collected over four time intervals (0900 hours to 1300 hours, 1300 hours to 1700 hours, 1700 hours to 2100 hours and 2100 hours to 0900 hours) on days 1, 5 and 14 to verify diurnal variation, and 24-h urine was collected to study day-to-day variation over 2 weeks. Urinary 6beta-hydroxycortisol and cortisol were determined by means of high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry.

RESULTS

The ratio of urinary 6beta-hydroxycortisol to cortisol exhibited noteworthy diurnal variation intra-individually; 2.8-fold on average. However, day-do-day intra-individual variation of the ratio was not observed over 2 weeks; the coefficient of variation was 11.9 +/- 3.0%.

CONCLUSION

The result indicates that imprudent use of random urine has a great risk of false evaluation in assessment of the 6beta-hydroxycortisol to cortisol ratio and that the ratio in 24-h urine samples provides a more robust measure of the inter-individual difference of this metabolic ratio, which to a certain but not complete extent represents the CYP3A activity.

Quantitative analysis of constitutive and inducible CYPs mRNA expression in the HepG2 cell line using reverse transcription-competitive PCR

Drug interactions which affect drug metabolism are of clinical importance. It is, however, difficult to estimate drug interactions in human from results obtained in animal experiments. In our previous study, we demonstrated that a combination of the HepG2 cell line and semiquantitative reverse transcription-PCR (RT-PCR) could be used to evaluate the degree of CYP3A mRNA induction by various drugs. Using an RT-competitive PCR (RT-cPCR) with beta-actin as the standard in this study, the constitutive and rifampicin (RFP)-induced expression of CYP3A4, CYP2C9, CYP2E1, and CYP1A2 mRNA in the HepG2 cells could be quantitatively and reproducibly determined. 120 h-treatment of HepG2 cells with 50 micromol/l RFP induced maximally 8.4- and 6.0-fold the expression of CYP3A4 and CYP2C9 mRNA, respectively, in comparison with untreated cells. On the other hand, mRNA level in CYP2E1 and CYP1A2 was not significantly changed by 50 micromol/l RFP after 24 to 120 h. To our knowledge, we report for the first time quantitative profiles of CYPs mRNA in HepG2 cells. This study demonstrates the efficiency of a combination of HepG2 cells and RT-cPCR in the evaluation of CYPs mRNA-induction by drugs.

Metallothionein acts as a cytoprotectant against doxorubicin toxicity

The protective role of metallothionein (MT) against the myocardiotoxicity and hepatotoxicity of doxorubicin (Dox) was investigated in mice. Dox-induced elevations of plasma creatine kinase activity, a measure of myocardiac damage, and plasma glutamate pyruvate transaminase activity, reflecting hepatic damage, were prevented by pretreatment with an MT inducer. Pretreatment with zinc induced MT in the liver and heart, thereby reducing Dox toxicity in these two organs. Pretratment with n-hexane also induced MT and reduced Dox toxicity, but only in the liver. In primary hepatocyte cultures, the leakage of lactate dehydrogenase induced by Dox was prevented by zinc pretreatment. These results suggest that MT induction prevents Dox toxicity in vivo and in vitro. Furthermore, we determined that MT-null mice were more sensitive to the myocardiotoxic and hepatotoxic effects of Dox. These findings indicate that both basal and induced MT protect against Dox toxicity.

Relationship between mRNA levels quantified by reverse transcription-competitive PCR and metabolic activity of CYP3A4 and CYP2E1 in human liver

Reverse transcription-competitive polymerase chain reaction is a powerful and sensitive tool for quantifying the absolute amount of mRNA. Using this method with beta-actin as the standard, we measured the mRNA level of CYP3A and CYP2E1 isoforms in human livers. We also determined the metabolic activities for both CYP isoforms. The absolute amounts of CYP3A4 and CYP2E1 mRNA in 15 liver tissues ranged from 15 to 5127 and 15163 to 69289 copies/10(4) copies of beta-actin (341- & 3.6-fold), respectively. The testosterone 6beta-hydroxylation for CYP3A4 and chlorzoxazone 6-hydroxylation activity for CYP2E1 ranged from 30 to 505 pmol/mg/min (16-fold) and from 0.59 to 2.73 nmol/mg/ml (3.6-fold), respectively. The correlation between the mRNA level and activity of CYP3A4 was significant (r = 0.94), while there was no significant correlation for CYP2E1 (r = 0.04). In conclusion, we observed a significant correlation between enzyme activity and mRNA expression for CYP3A4 but not for CYP2E1. This fact indicates that CYP2E1, in addition to being less variable between individuals than CYP3A4, differs in its regulation mechanism.

Effects of antisense oligonucleotides to the cardiac Na+/Ca2+ exchanger on calcium dynamics in cultured cardiac myocytes

The present study was designed to explore the role of the Na+/Ca2+ exchanger on spontaneous beating of cultured cardiac myocytes. Antisense oligonucleotides (AS) based on the sequence of the cardiac Na+/Ca2+ exchanger were used to decrease expression of this Ca2+ transporting protein in cardiac myocytes. An application of AS (10 microM) caused an increase in beating rate of myocytes within 6-24 h. After 24 h of exposure, AS increased the beating rate from an average rate of 77 beats/min in control and sense-treated myocytes to 103 beats/min. Moreover, myocytes treated for 24 h with 10 microM AS exhibited an increase in diastolic [Ca2+]i levels. The antisense treatment also led to a approximately 20% decrease in expression of Na+/Ca2+ exchanger proteins within 6-24 h. Changes in mRNA levels following AS treatment could not be detected within 3- to 24-h periods. The results of these studies suggest that the Na+/Ca2+ exchanger plays a potentiating role in spontaneous the beating process by regulating [Ca2+]i dynamics and that even a small reduction in the levels of the exchanger protein has marked effects on the handling of [Ca2+]i during the cardiac cycle.

Effect of the CYP2D6*10 genotype on venlafaxine pharmacokinetics in healthy adult volunteers

AIMS

Interindividual differences in the pharmacokinetics of venlafaxine, a new antidepressant, were shown during early clinical trials in Japan. Venlafaxine is metabolized mainly by CYP2D6 to an active metabolite, O-desmethylvenlafaxine (ODV). Therefore, the influence of the CYP2D6 genotypes on venlafaxine pharmacokinetics was examined in a Japanese population.

METHODS

Twelve adult Japanese men in good health participated in this study. Genomic DNA was isolated from peripheral lymphocytes, and the CYP2D6 genotypes were determined by codon 188C/T, 1934G/A, 2938G/A and 4268G/C mutations using endonuclease tests based on PCR and by Xba I-RFLP analysis. Subjects were categorized into the following 3 groups (n=4 in each group); Group1: CYP2D6*10/*10, *5/*10, Group2: CYP2D6*1/*10, *2/*10 and Group3: CYP2D6*1/*1, CYP2D6*1/*2. Venlafaxine (25 mg, n=6; 37.5 mg, n=6) was administered orally at 09.00 h following an overnight fast. Plasma concentrations of venlafaxine and ODV were monitored by h.p.l.c. for 48 h.

RESULTS

The Cmax and AUC of venlafaxine were 184% and 484% higher in the group 1 subjects than in the group 3 subjects, and 101% and 203% higher in the group 1 than in the group 2, respectively.

CONCLUSIONS

These results suggest that CYP2D6*10 influences the pharmacokinetics of venlafaxine in a Japanese population.

CYP2C19 genotypes and omeprazole metabolism after single and repeated dosing when combined with clarithromycin

OBJECTIVES

Omeprazole is metabolized mainly by CYP2C19 which has two major mutations (CYP2C19*2 in exon5 and CYP2C19*3 in exon4) associated with the poor metabolizer (PM) phenotype. The aim of this study was to examine the relationship between genetic polymorphism of CYP2C19 and metabolism of omeprazole administrated as a single dose or as repeated-doses, which were in both cases co-administered with clarithromycin.

METHODS

Twelve healthy Japanese subjects were typed for CYP2C19 polymorphism. In the single-dose study, plasma levels of omeprazole and its metabolites were measured for 24 h after administration of 20 mg omeprazole and 400 mg clarithromycin to six healthy Japanese subjects. In the repeated-dose study, plasma levels of omeprazole and its metabolites were measured after repeated oral administration of 20 mg omeprazole and 400 mg clarithromycin twice daily for 6 days and then after 20 mg omeprazole and 400 mg clarithromycin once on the 7th day to the other 6 healthy Japanese subjects.

RESULTS

In the single-dose study, the areas under the plasma concentration-versus-time curve (AUCs) of omeprazole of homozygotes for the wild-type allele (*1/*1 n = 2), heterozygotes (n = 3) for the CYP2C19*2 (*1/ *2) or for the CYP2C19*3 (*1/*3) and heterozygote (n = 1) for the two defects (*2/*3) were on average 450, 1007 and 6710 ng x h(-1) x ml(-1), respectively. The ratios of AUCs of omeprazole/5-hydroxyomeprazole for *1/*1, *1/*2 or *1/*3 and *2/*3 were 1, 2 and 30, respectively. In the repeated-dose study, the AUCs of omeprazole for * 1/ *1, *1/*2 or *1/*3 and *2/*3 were 4041 (n = 2), 3149 (n = 3) and 6684 (n = 1) ng x h(-1) x ml(-1), respectively. The ratios of AUCs of omeprazole/5-hydroxyomeprazole for *1/*1, * 1/*2 or * 1/*3 and *2/*3 were7, 11 and 30, respectively. In the repeated-dose study, the AUC of omeprazole of * 1/*1 genotypes was nine-fold higher, that of *1/*2 and *1/*3 genotypes was three-fold higher, and the Cmax value of omeprazole was three-fold higher compared with subjects with the same genotype in the single-dose study. However, there were few differences in the AUC and Cmax of omeprazole between the *2/*3 genotype in the single-dose study and the homozygote for the CYP2C19*2 (*2/*2) in the repeated-dose study.

CONCLUSION

Subjects with *1/*1, *1/*2 and *1/*3 genotypes in the repeated-dose study had lower CYP2C19 activity than subjects of the same genotype in the single-dose study. The difference in omeprazole metabolism between subjects with different genotypes observed on day 1 seemed to disappear after 7 days of repeated-dose administration.

Shape and size changes induced by taurine depletion in neonatal cardiomyocytes

Taurine is a very important organic osmolyte in most adult cells. Because of this property it has been proposed that large changes in the intracellular content of taurine can osmotically stress the cell, causing changes in its size and shape. This hypothesis was examined by measuring cell dimensions of taurine deficient cardiomyocytes using confocal microscopy. Incubation of isolated neonatal rat myocytes with medium containing 5 mM beta-alanine led to a 55% decrease in intracellular taurine content. Associated with the loss of taurine was a reduction in cell size. Two factors contributed to the change in cell size. First, there was a shift in cell shape, favoring the smaller of the two cellular configurations commonly found in the myocyte cell culture. Second, the size of the polyhedral configuration was reduced after beta-alanine treatment. These same two events also contributed to size reduction in cardiomyocytes incubated with medium containing 30 mM mannitol. Nonetheless, some qualitative differences exist between cells osmotically stressed by increasing the osmolality of the incubation medium and decreasing intracellular osmolality. The results support a role for taurine in the regulation of osmotic balance in the neonatal cardiomyocyte.