Apical tooth germ cell-conditioned medium enhances the differentiation of periodontal ligament stem cells into cementum/periodontal ligament-like tissues

BACKGROUND AND OBJECTIVE

Limitations of current periodontal regeneration modalities in both predictability and extent of healing response, especially on new cementum and attachment formation, underscore the importance of restoring or providing a microenvironment that is capable of promoting the differentiation of periodontal ligament stem cells (PDLSCs) towards cementoblast-like cells and the formation of cementum/periodontal ligament-like tissues. The aim of this study was to investigate the biological effect of conditioned medium from developing apical tooth germ cells (APTG-CM) on the differentiation and cementogenesis of PDLSCs both in vitro and in vivo.

MATERIAL AND METHODS

Using the limiting dilution technique, single-colony-derived human PDLSCs were isolated and expanded to obtain homogeneous populations of PDLSCs. Morphological appearance, cell cycle analysis, bromodeoxyuridine incorporation, alkaline phosphatase (ALP) activity, mineralization behavior, gene expression of cementoblast phenotype and in vivo differentiation capacities of PDLSCs co-cultured with APTG-CM were evaluated.

RESULTS

The induced PDLSCs exhibited several characteristics of cementoblast lineages, as indicated by the morphological changes, increased proliferation, high ALP activity, and the expression of cementum-related genes and calcified nodule formation in vitro. When transplanted into immunocompromised mice, the induced PDLSCs showed tissue-regenerative capacity to produce cementum/periodontal ligament-like structures, characterized by a layer of cementum-like mineralized tissues and associated periodontal ligament-like collagen fibers connecting with the newly formed cementum-like deposits, whereas control, untreated PDLSCs transplants mainly formed connective tissues.

CONCLUSION

Our findings suggest that APTG-CM is able to provide a cementogenic microenvironment and induce differentiation of PDLSCs along the cementoblastic lineage. This has important implications for periodontal engineering.

Detection of Virulence to Resistance Gene Sr24 Within Race TTKS of Puccinia graminis f. sp. tritici

The stem rust resistance gene Sr24 is effective against most races of Puccinia graminis f. sp. tritici, including race TTKS (syn. Ug99), and is used widely in commercial wheat cultivars worldwide. In 2006, susceptible infection responses were observed on wheat lines and cultivars carrying Sr24 in a field stem rust screening nursery at Njoro, Kenya. We derived 28 single-pustule isolates from stem rust samples collected from the 2006 Njoro nursery. The isolates were evaluated for virulence on 16 North American stem rust differential lines; on wheat lines carrying Sr24, Sr31, Sr38, and SrMcN; and on a wheat cultivar with a combination of Sr24 and Sr31. All isolates were identified as race TTKS with additional virulence on Sr31 and Sr38. These isolates were divided into two groups: group A (seven isolates and the two control isolates), producing a low infection type, and group B (21 isolates), producing a high infection type on Sr24, respectively. Isolates of group B represented a new variant of race TTKS with virulence to Sr24. Eighteen simple sequence repeat (SSR) markers were used to examine the genetic relationship between these two groups of isolates in race TTKS and five North American races (MCCF, QCCQ, RCRS, RTHS, and TPMK) that are representative of distinct lineage groups. All isolates of race TTKS shared an identical SSR genotype and were clearly different from North American races. The virulence and SSR data indicated that the new variant of race TTKS with Sr24 virulence likely has arisen via mutation within the TTKS genetic lineage. We propose to revise the North American stem rust nomenclature system by the addition of four genes (Sr24, Sr31, Sr38, and SrMcN) as the fifth set. This revision recognizes the virulence on Sr31 and differentiates isolates within race TTKS into two separate races: TTKSK and TTKST, with avirulence and virulence on Sr24, respectively. The occurrence of race TTKST with combined virulence on Sr24 and Sr31 has substantially increased the vulnerability of wheat to stem rust worldwide.

Search for the invisible decay of J/psi in psi(2S) --> pi(+)pi(-) J/psi

Using psi(2S) --> pi(+)pi(-) J/psi events in a sample of 14.0 x 10(6) psi(2S) decays collected with the BES-II detector, a search for the decay of the J/psi to invisible final states is performed. No signal is found, and an upper limit at the 90% confidence level is determined to be 1.2 x 10(-2) for the ratio B(J/psi --> invisible)/B(J/psi-->mu(+)mu(-)). This is the first search for J/psi decays to invisible final states.

A five-year follow-up study of goiter and thyroid nodules in three regions with different iodine intakes in China

OBJECTIVE

The association between iodine status and the prevalence of goiter and thyroid nodules has been well established but the extent to which different iodine intake levels influence the incidence of goiter and thyroid nodules is unclear. The aim of the study was to determine the incidence of goiter and thyroid nodules in 3 regions with different iodine intake levels: mildly deficient, more than adequate, and excessive.

DESIGN, PATIENTS AND MEASUREMENTS

Of the 3385 unselected subjects enrolled in 1999 in Panshan, Zhangwu, and Huanghua where median urinary iodine excretion (UIE) was 83.5 microg/l, 242.9 microg/l, and 650.9 microg/l, respectively, 2708 (80.0%) participated in the follow-up study in 2004. The examinations of thyroid ultrasonography, thyroid function, thyroid autoantibodies and UIE were performed at baseline and follow-up.

RESULTS

The cumulative incidence of diffuse goiter was 7.1%, 4.4%, and 6.9%, respectively, higher in Panshan and Huanghua than in Zhangwu (p=0.013 and p=0.015) and that of nodular goiter was 5.0%, 2.4%, and 0.8%, respectively, declining with increasing iodine intake levels (p<0.001). Mild iodine deficiency, chronic iodine excess as well as positive thyroid autoantibodies were associated with the occurrence of goiter [Logistic regression: odds ratio (OR)=1.83 (95% confidence interval (CI) 1.26-2.65), OR=1.46 (95% CI 1.01-2.11) and OR=1.68 (95% CI 1.14-2.48), respectively]. The cumulative incidence of single nodule was 4.0%, 5.7%, and 5.6%, respectively and that of multiple nodules was 0.4%, 1.2%, and 1.0%, respectively.

CONCLUSIONS

The relationship between iodine and the risk for the occurrence of diffuse goiter shows a U-shaped curve. Nodular goiters are more prevalent in iodine-deficient areas.

Electron beam irradiation improves shelf lives of Korean ginseng (Panax ginseng C.A. Meyer) and red ginseng

Effect of electron beam irradiation on microbial growth and qualities of vacuum-packaged Korean ginseng and red ginseng during storage was investigated. Korean ginseng and red ginseng were treated at irradiation doses of 0, 2, 8, and 16 kGy. After treatment, samples were individually vacuum-packaged and stored at 20 degrees C. Microbial growth results of the irradiated samples presented that populations of total bacteria, yeast and mold, and total coliforms were decreased by 2 to 3 log CFU/g. The pH values of the samples were not significantly different among treatments. Thiobarbituric acid-reactive substance values of the samples increased during storage. Electron beam treatment caused negligible changes in Hunter's color L, a, and b values among the samples. Sensory evaluations like color and odor of the samples exhibited that there were no significant changes among the samples. During storage, content of saponin, a leading compound in ginseng, was not affected by irradiation. These results suggest that electron beam treatment should be useful in extending shelf lives of Korean ginseng and red ginseng.

Genetic and QTL analysis of resistance to Xiphinema index in a grapevine cross

Resistance to the dagger nematode Xiphinema index has been an important objective in grape rootstock breeding programs. This nematode not only causes severe feeding damage to the root system, but it also vectors grapevine fanleaf virus (GFLV), the causal agent of fanleaf degeneration and one of the most severe viral diseases of grape. The established screening procedures for dagger nematode resistance are time consuming and can produce inconsistent results. A fast and reliable greenhouse-based system for screening resistance to X. index that is suitable for genetic studies and capable of evaluating breeding populations is needed. In this report, the dynamics of nematode numbers, gall formation, and root weight loss were investigated using a variety of soil mixes and pot sizes over a 52-week period. Results indicated that the number of galls formed was correlated with the size of the nematode population and with the degree of root weight loss. After inoculation with 100 nematodes, gall formation could be reliably evaluated in 4-8 weeks in most plant growth conditions and results were obtained 6 months more rapidly than past evaluation methods. This modified X. index resistance screening method was successfully applied to 185 of the 188 F(1) progeny from a cross of D8909-15 x F8909-17 (the 9621 population), which segregates for a form of X. index resistance originally derived from Vitis arizonica. Quantitative trait loci (QTL) analysis was carried out on both parental genetic maps of 255 markers using MapQTL 4.0. Results revealed that X. index resistance is controlled by a major QTL, designated Xiphinema index Resistance 1 (XiR1), near marker VMC5a10 on chromosome 19. The XiR1 QTL was supported by a LOD score of 36.9 and explained 59.9% of the resistance variance in the mapping population.

Functional analysis of the Arabidopsis PHT4 family of intracellular phosphate transporters

The transport of phosphate (Pi) between subcellular compartments is central to metabolic regulation. Although some of the transporters involved in controlling the intracellular distribution of Pi have been identified in plants, others are predicted from genetic, biochemical and bioinformatics studies. Heterologous expression in yeast, and gene expression and localization in plants were used to characterize all six members of an Arabidopsis thaliana membrane transporter family designated here as PHT4. PHT4 proteins share similarity with SLC17/type I Pi transporters, a diverse group of animal proteins involved in the transport of Pi, organic anions and chloride. All of the PHT4 proteins mediate Pi transport in yeast with high specificity. Bioinformatic analysis and localization of PHT4-GFP fusion proteins indicate that five of the proteins are targeted to the plastid envelope, and the sixth resides in the Golgi apparatus. PHT4 genes are expressed in both roots and leaves, although two of the genes are expressed predominantly in leaves and one mostly in roots. These expression patterns, together with Pi transport activities and subcellular locations, suggest roles for PHT4 proteins in the transport of Pi between the cytosol and chloroplasts, heterotrophic plastids and the Golgi apparatus.

Experimental test of the high-frequency quantum shot noise theory in a quantum point contact

We report on direct measurements of the electronic shot noise of a quantum point contact at frequencies nu in the range 4-8 GHz. The very small energy scale used ensures energy independent transmissions of the few transmitted electronic modes and their accurate knowledge. Both the thermal energy and the quantum point contact drain-source voltage V_{ds} are comparable to the photon energy hnu leading to observation of the shot noise suppression when V_{ds}<hnu/e. Our measurements provide the first complete test of the finite frequency shot noise scattering theory without adjustable parameters.

Effects of calcitonin gene-related peptide on apoptosis of peripheral blood mononuclear cells from patients with systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease with abnormal apoptosis and autoantibody production. Calcitonin gene-related peptide (CGRP) is a neuropeptide produced by the central and peripheral nervous systems and by endocrine cells. It can influence cell death in thymocytes and cultured smooth muscle cells, and inhibits the production of interleukin (IL)-2, which inhibits apoptosis.

AIMS

To investigate the effects of calcitonin gene-related peptide (CGRP) on apoptosis of peripheral blood mononuclear cells (PBMCs) from patients with SLE.

METHODS

The percentage of apoptosis of PBMCs from patients with SLE and healthy blood donors were examined using annexin-V/propidine iodide staining 48 h after culturing with CGRP and/or its receptor antagonist CGRP(8-37) at various concentrations. IL-2 activity in culture supernatants was determined using the incorporation of 3H-TdR by the IL-2-dependent cell line CTLL and evaluated by ELISA.

RESULTS

The percentage of spontaneous apoptosis of PBMCs from patients with SLE was higher than that of healthy blood donors (34.18 +/- 2.86 vs. 18.23 +/- 0.81, P < 0.001). CGRP, at all tested concentrations, had no effect on apoptosis of PBMCs from healthy blood donors, but significantly inhibited apoptosis of PBMCs from patients with SLE at concentrations of >or= 0.5 x 10(-8) mol/L (0.5 x 10(-8) mol/L: 32.01 +/- 3.98 vs. 34.18 +/- 2.86, P < 0.05; 1.0 x 0(-8) mol/L: 26.76 +/- 2.69 vs. 34.18 +/- 2.86, P < 0.001; 1.5 x 10(-8) mol/L: 25.97 +/- 2.65 vs. 34.18 +/- 2.86, P < 0.001), and the effect plateaued at 1.0 x 10(-8) mol/L, at which level inhibition was not significantly increased with increasing concentration. However, CGRP, at any concentration tested, could not reduce the rate of apoptosis of PBMCs from patients with SLE to the normal range. There were significant positive relationships between the effect of CGRP, on apoptosis of PBMCs and SLE Disease Activity Index (0.5 x 10(-8) mol/L: r(s) = 0.328, P < 0.05; 1.0 x 10(-8) mol/L: r(s) = 0.431, P < 0.01; 1.5 x 10(-8) mol/L: r(s) = 0.419, P < 0.01). CGRP(8-37) itself had no effect on apoptosis, but was able to block the effects of CGRP on PBMCs (0.5 x 10(-8) mol/L: 32.01 +/- 3.98 vs. 33.12 +/- 2.37, P < 0.05; 1.0 x 10(-8) mol/L: 26.76 +/- 2.69 vs. 34.73 +/- 2.32, P < 0.001; 1.5 x 10(-8) mol/L: 25.97 +/- 2.65 vs. 35.25 +/- 3.37, P < 0.001). There was no effect of CGRP on IL-2 production.

CONCLUSIONS

These results indicate that CGRP plays an important role in the apoptosis of PBMCs from patients with SLE via its receptor; low plasma levels of CGRP may cause accelerated apoptosis. This regulation does not seem to be related to IL-2.

Characterization of Seedling Infection Types and Adult Plant Infection Responses of Monogenic Sr Gene Lines to Race TTKS of Puccinia graminis f. sp. tritici

Stem rust, caused by Puccinia graminis f. sp. tritici, historically was one of the most destructive diseases of wheat and barley. The disease has been under effective control worldwide through the widespread use of host resistance. A number of stem rust resistance genes in wheat have been characterized for their reactions to specific races of P. graminis f. sp. tritici. Adult plant responses to race TTKS (also known as Ug99) of monogenic lines for Sr genes, a direct measurement of the effectiveness for a given gene, have not been investigated to any extent. This report summarizes adult plant infection responses and seedling infection types for monogenic lines of designated Sr genes challenged with race TTKS. High infection types at the seedling stage and susceptible infection responses in adult plants were observed on monogenic lines carrying Sr5, 6, 7a, 7b, 8a, 8b, 9a, 9b, 9d, 9g, 10, 11, 12, 15, 16, 17, 18, 19, 20, 23, 30, 31, 34, 38, and Wld-1. Monogenic lines of resistance genes Sr13, 22, 24, 25, 26, 27, 28, 32, 33, 35, 36, 37, 39, 40, 44, Tmp, and Tt-3 were effective against TTKS both at the seedling and adult plant stages. The low infection types to race TTKS observed for these resistance genes corresponded to the expected low infections of these genes to other incompatible races of P. graminis f. sp. tritici. The level of resistance conferred by these genes at the adult plant stage varied between highly resistant to moderately susceptible. The results from this study were inconclusive for determining the effectiveness of resistance genes Sr9e, 14, 21, and 29 against race TTKS. The understanding of the effectiveness of individual Sr genes against race TTKS will facilitate the utilization of these genes in breeding for stem rust resistance in wheat.

Successful application of tissue-engineered skin to refractory ulcers

In this study, the effectiveness of a tissue-engineered skin (Activskin; Aierfu, Xi'an, China) was evaluated for the treatment of various refractory ulcers. These ulcers were treated with Activskin after debridement and irrigation with saline. A second application of Activskin was essential if the first application failed to persist on the wounds. Clinical efficacy and safety were assessed at regular clinic visits during 6 months of follow-up. All 11 treated patients improved with Activskin. The ulcers healed by inward migration from the wound edge. The average healing time was 27.8 days. No recurrent ulceration or other adverse events were observed during follow-up. These results provide preliminary evidence that Activskin is safe and effective in the management of refractory ulcers.

Estrogen receptor genotypes, menopausal status, and the lipid effects of tamoxifen

Tamoxifen induces important changes in serum lipid profiles in some women; however, little information is available to predict which women will experience improved lipid profiles during tamoxifen therapy. As part of a multicenter prospective observational trial in 176 breast cancer patients, we tested the hypothesis that tamoxifen-induced lipid changes were associated with genetic variants in candidate target genes (CYP2D6, ESR1, and ESR2). Tamoxifen lowered low-density lipoprotein cholesterol (P<0.0001) by 23.5 mg/dl (13.5-33.5 mg/dl) and increased triglycerides (P=0.006). In postmenopausal women, the ESR1-XbaI and ESR2-02 genotypes were associated with tamoxifen-induced changes in total cholesterol (P=0.03; GG vs GA/AA) and triglycerides (P=0.01; gene-dose effect), respectively. In premenopausal women, the ESR1-XbaI genotypes were associated with tamoxifen-induced changes in triglycerides (P=0.002; gene-dose effect) and high-density lipoprotein (P=0.004; gene-dose effect). Our results suggest that estrogen receptor genotyping may be useful in predicting which women would benefit more from tamoxifen.

Tamoxifen-induced hot flashes are associated with estrogen receptor polymorphisms

501

Background: Hot flashes are the most common side effect of tamoxifen. The pharmacogenetic predictors of hot flashes are not known. We hypothesized that estrogen receptor (ER) genotypes that have been associated with clinical phenotypes may predict the frequency and composite score of tamoxifen-associated hot flashes. Methods: We conducted a prospective observational study in 3 academic centers to evaluate the associations between ER and hot flash composite scores in women with breast cancer during the first year of adjuvant tamoxifen treatment. Menopausal status and prior chemotherapy history were collected at baseline. Medication records and validated hot flash diaries were prospectively collected before and following 1, 4, 8 and 12 months of starting tamoxifen. ERa (ESR1) PvuII (rs2234693) and XbaI (rs9340799) genotypes were determined using a Restriction Fragment Length Polymorphism (RFLP) assay; and ERβ (ESR2–02; rs4986938) genotype was determined using a Taqman™ assay. The haplotype of two ESR1 SNPs and their association with the baseline hot flash score were analyzed with haplo.stat function in R. Individual SNPs and their interactions in baseline hot flash score and month 4 hot flash score change were analyzed with SAS PROC GLM. Results: Of the 298 women recruited to the trial, 286 returned their baseline diaries and 251, 239, 214, and 213 women returned their diaries 1, 4, 8, and 12 months after tamoxifen treatment. At baseline, premenopausal women who were homozygous for the ESR1 CG haplotype reported higher hot flash scores (17.2±3.7) than carriers with one or less CG allele (5.2±3.9), p=0.01. After tamoxifen treatment, postmenopausal women with ESR1 PvuII CC and ESR2–02 GG genotype had the greatest increase (p=0.0004) in hot flash score (53.9±16.4) as compared with women with other genotypes (12.5±3.6). Women who were homozygous for the ESR2–02 AA allele were significantly less likely to experience tamoxifen-induced hot flashes than women with at least one G allele (OR=4.0, P=0.0006) regardless of menopausal status and chemotherapy history. CYP2D6 analysis in underway and results will be available for the meeting. Conclusions: Menopausal status, history of prior chemotherapy, and ER genotype may be used to predict who may suffer hot flashes during tamoxifen treatment.

[Table: see text]

An on-demand coherent single-electron source

We report on the electron analog of the single-photon gun. On-demand single-electron injection in a quantum conductor was obtained using a quantum dot connected to the conductor via a tunnel barrier. Electron emission was triggered by the application of a potential step that compensated for the dot-charging energy. Depending on the barrier transparency, the quantum emission time ranged from 0.1 to 10 nanoseconds. The single-electron source should prove useful for the use of quantum bits in ballistic conductors. Additionally, periodic sequences of single-electron emission and absorption generate a quantized alternating current.

Predicting the development of early skin test sensitization in offspring of parents with asthma

BACKGROUND

The direct causal relationship between skin sensitization and asthma are controversial until now and remains to be further researched. Our aim is to analyse the role of parental asthma in the development of skin sensitization in offspring.

MATERIALS AND METHODS

This study was performed among nuclear families (determined by index of asthma patients), and subjects included parents and offspring. Parents were subdivided into four phenotypes on the basis of skin sensitization (SPT+ or SPT-) and asthma status (AST+ or AST-) and offspring were subdivided into three age groups: 3-8, 9-14 and 15-20 years. The main tests included a standard questionnaire and skin prick tests.

RESULTS

Offspring's skin sensitization differed among parental phenotypes at all ages (P < 0.05). In the SPT+/AST-, SPT-/AST+ and SPT+/AST+ groups, offspring were significantly more likely to be allergic than the ones in SPT-/AST- group at 3-8 years. Offspring with at least one parent with asthma were significantly more likely to have positive skin prick test response than those with non-asthmatic parents at age 3-8 years and 9-14 years, but not at 15-20 years among offspring with allergic parents. Results were independent of asthma in the children and of the characteristics of atopy in the parents.

CONCLUSION

Parent asthma history is an independent risk factor for allergic sensitization in their offspring in a Chinese population.

Letter Code System of Nomenclature for Puccinia graminis f. sp. avenae

Current systems that describe the virulence phenotype in Puccinia graminis f. sp. avenae lack a systematic approach for the naming of races or to provide easily made comparisons of virulence among races. A new nomenclature system that simply and systematically characterizes virulence in P. graminis f. sp. avenae is described. The new system has the distinct advantage of providing easily seen relationships among races in contrast to previous nomenclature systems. This allows for easier interpretation of virulence relationships in the oat stem rust population and provides a large amount of virulence information with a minimum of written characters. This system uses single-gene differential lines with the resistance genes Pg1, Pg2, Pg3, Pg4, Pg6, Pg8, Pg9, Pg10, Pg12, Pg13, Pg15, and Pg16, grouped into three subsets of four lines in sequential Pg gene order. By grouping in sequential gene number order, the relationship of the new system to the "standard" system is easily seen. Each race is designated by a three-letter code, based on the seedling reaction (low or high) on 12 differential lines. The letter code nomenclature system is open ended and can be updated easily as new differential genes are identified. This system simply and precisely describes the virulence phenotypes of isolates of P. graminis f. sp. avenae, and allows for easily made comparisons of virulence of isolates collected over time and across geographical locations worldwide.

Indirubin-3'-monoxime inhibits autophosphorylation of FGFR1 and stimulates ERK1/2 activity via p38 MAPK

Indirubin-3'-monoxime is a derivative of the bis-indole alkaloid indirubin, an active ingredient of a traditional Chinese medical preparation that exhibits anti-inflammatory and anti-leukemic activities. Indirubin-3'-monoxime is mainly recognized as an inhibitor of cyclin-dependent kinases (CDKs) and glycogen synthase kinase-3. It inhibits proliferation of cultured cells, mainly through arresting the cells in the G1/S or G2/M phase of the cell cycle. Here, we report that indirubin-3'-monoxime is able to inhibit proliferation of NIH/3T3 cells by specifically inhibiting autophosphorylation of fibroblast growth factor receptor 1 (FGFR1), blocking in this way the receptor-mediated cell signaling. Indirubin-3'-monoxime inhibits the activity of FGFR1 at a concentration lower than that required for inhibition of phosphorylation of CDK2 and retinoblastoma protein and cell proliferation stimulated by fetal calf serum. The ability of indirubin-3'-monoxime to inhibit FGFR1 signaling was similar to that of the FGFR1 inhibitor SU5402. In addition, we found that indirubin-3'-monoxime activates long-term p38 mitogen-activated protein kinase activity, which stimulates extracellular signal-regulated kinase 1/2 in a way unrelated to the activity of FGFR1. Furthermore, we show that indirubin-3'-monoxime can inhibit proliferation of the myeloid leukemia cell line KG-1a through inhibition of the activity of the FGFR1 tyrosine kinase. The data presented here demonstrate previously unknown activities of indirubin-3'-monoxime that may have clinical implications.

Relaxation time of a chiral quantum R-L circuit

We report on the GHz complex admittance of a chiral one-dimensional ballistic conductor formed by edge states in the quantum Hall regime. The circuit consists of a wide Hall bar (the inductor L) in series with a tunable resistor (R) formed by a quantum point contact. Electron interactions between edges are screened by a pair of side gates. Conductance steps are observed on both real and imaginary parts of the admittance. Remarkably, the phase of the admittance is transmission independent. This shows that the relaxation time of a chiral R -L circuit is resistance independent. A current and charge conserving scattering theory is presented that accounts for this observation with a relaxation time given by the electronic transit time in the circuit.

Cytochrome P450 3A5 genotype is associated with verapamil response in healthy subjects

We hypothesized that CYP3A5 genotype contributes to the interindividual variability in verapamil response. Healthy subjects (n=26) with predetermined CYP3A5 genotypes were categorized as expressers (at least one CYP3A5(*)1 allele) and nonexpressers (subjects without a CYP3A5(*)1 allele). Verapamil pharmacokinetics and pharmacodynamics were determined after 7 days of dosing with 240 mg daily. There was a significantly higher oral clearance of R-verapamil (165.1+/-86.4 versus 91.2+/-36.5 l/h; P=0.009) and S-verapamil (919.4+/-517.4 versus 460.2+/-239.7 l/h; P=0.01) in CYP3A5 expressers compared to nonexpressers. Consequently, CYP3A5 expressers had significantly less PR-interval prolongation (19.5+/-12.3 versus 44.0+/-19.4 ms; P=0.0004), and had higher diastolic blood pressure (69.2+/-7.5 versus 61.6+/-5.1 mm Hg; P=0.036) than CYP3A5 nonexpressers after 7 days dosing with verapamil. CYP3A5 expressers display a greater steady-state oral clearance of verapamil and may therefore experience diminished pharmacological effect of verapamil due to a greater steady state oral clearance.