Stefan Viktor Vormfelde

The Social Phobia Psychotherapy Research Network : The First Multicenter Randomized Controlled Trial of Psychotherapy for Social Phobia: Rationale, Methods and Patient Characteristics

This paper presents the Social Phobia Psychotherapy Research Network. The research program encompasses a coordinated group of studies adopting a standard protocol and an agreed-on set of standardized measures for the assessment and treatment of social phobia (SP). In the central project (study A), a multicenter randomized controlled trial, refined models of manualized cognitive-behavioral therapy and manualized short-term psychodynamic psychotherapy are compared in the treatment of SP. A sample of 512 outpatients will be randomized to either cognitive-behavioral therapy, short-term psychodynamic psychotherapy or waiting list. Assessments will be made at baseline, at the end of treatment and 6 and 12 months after the end of treatment. For quality assurance and treatment integrity, a specific project using highly elaborated measures has been established (project Q). Study A is complemented by 4 interrelated add-on projects focusing on attachment style (study B1), on cost-effectiveness (study B2), on variation in the serotonin transporter gene in SP (study C1) and on structural and functional deviations of the hippocampus and amygdala (study C2). Thus, the Social Phobia Psychotherapy Research Network program enables a highly interdisciplinary research into SP. The unique sample size achieved by the multicenter approach allows for studies of subgroups (e.g. comorbid disorders, isolated vs. generalized SP), of responders and nonresponders of each treatment approach, for generalization of results and for a sufficient power to detect differences between treatments. Psychological and biological parameters will be related to treatment outcome, and variables for differential treatment indication will be gained. Thus, the results provided by the network may have an important impact on the treatment of SP and on the development of treatment guidelines for SP.

Interindividual Variation in the Pharmacokinetics of Δ9-Tetrahydrocannabinol as Related to Genetic Polymorphisms in CYP2C9

The impact of the CYP2C9 polymorphism on the pharmacokinetics of orally administered Δ9‐tetrahydrocannabinol (THC) was studied in 43 healthy volunteers. THC pharmacokinetics did not differ by CYP2C9*2 allele status. However, the median area under the curve of THC was threefold higher and that of 11‐nor‐9‐carboxy‐9‐tetrahydrocannabinol was 70% lower in CYP2C9*3/*3 homozygotes than in CYP2C9*1/*1 homozygotes. CYP2C9*3 carriers also showed a trend toward increased sedation following administration of THC. Therefore, the CYP2C9*3 variant may influence both the therapeutic and adverse effects of THC.

The Polymorphisms Asn130Asp and Val174Ala in OATP1B1 and the CYP2C9 Allele *3 Independently Affect Torsemide Pharmacokinetics and Pharmacodynamics

To the editor: We investigated two organic anion transporting polypeptide 1B1 (OATP1B1) polymorphisms in relation to torsemide pharmacokinetics and pharmacodynamics. The major conclusions are as follows: (1) OATP1B1 transports torsemide; (2) OATP1B1 supposedly also transports other CYP2C9 substrates; (3) the polymorphisms Asn130Asp and Val174Ala affected kinetics independently; (4) haplotype analysis was necessary to detect their independent impact; (5) together, CYP2C9, OATP1B1, OAT1, and OAT4 polymorphisms explained nearly 50% pharmacokinetic variation; and (6) this example of significant gene–gene interactions may stimulate future research to conjointly consider enzyme and transporter polymorphisms. We hypothesized genetic variability in hepatocellular torsemide uptake because polymorphisms affecting torsemide’s biotransformation and renal excretion only incompletely explained the variation in its pharmacokinetics. Polymorphisms affecting the hepatocellular uptake of other anions have been reported in OATP1B1 (synonyms SLCO1B1, OATP-C, OATP2, LST1). We explored the impact of the OATP1B1 polymorphisms Asn130Asp and Val174Ala in our study with 10mg torsemide in 99 healthy Caucasians. Asn130Asp (rs2306283) and Val174Ala (rs4149056) had minor allele frequencies of 0.393 and 0.173. They were in moderate linkage disequilibrium (D0 1⁄4 0.62, 95% CI: 0.34–0.8, LOD (logarithm of odds) score: 2.85). Four haplotypes resulted: Asn130Val174 (synonym *1a), Asp130Val174 (*1b), Asn130Ala174 (*5), and Asp130Ala174 observed at allele frequencies of 0.577, 0.246, 0.027, and 0.150. Total oral torsemide clearance (Cl/F) was associated with the Val174Ala polymorphism with 62+3, 46+3, and 41+5ml/min (mean+SE) in Val/Val, Val/Ala, and Ala/Ala carriers (Po0.001) it was not statistically significantly associated with Asn130Asp (55+3, 54+3, 64+3ml/min in Asn/Asn, Asp/Asn, Asp/Asp). It was the haplotype–phenotype analysis that revealed a consistently higher clearance with aspartate130: total oral clearance was 56+3, 73+7, 27+16, and 41+9ml/min in homozygous Asn130Val174, Asp130Val174, Asn130Ala174, and Asp130Ala174 carriers (Po0.01, multiple linear regression). The corresponding extrarenal clearance was 40+3, 56+5, 13+12, and 26+7 (Po0.001). Especially, the Asp130Val174 haplotype was clearly associated with the torsemide clearance (Figure 1). We previously reported that the CYP2C9*3 allele is associated with reduced torsemide biotransformation and that polymorphisms in the organic anion transporters OAT1 and OAT4 alter renal torsemide clearance. The associations with the OATP1B1 alleles and those in CYP2 C9 (Figure 2), OAT1, and OAT4 were independent of each other. A fraction of 15.5% of variation was explained by the OATP1B1 haplotypes, roughly additive to approximately 20% explained by CYP2C9 and the 10% explained by OAT1 and OAT4, resulting in 46.7% variation now explained in the total oral torsemide clearance. This is a prime example showing how pharmacokinetic variation in a substrate of a polymorphic enzyme can be substantially better explained by including genetic variation in a transporter that mediates variable access to this enzyme (Fig u re 2 ). Renal torsemide excretion was higher with lower clearing OATP1B1 alleles and vice versa (Figure 1). Mean renal torsemide excretion was 2.8+0.1, 3.2+0.1, and 4.5+0.1mg with no, one, and two alanine174 alleles (Po0.001). It was not associated with the Asn130Asp po lymorphism (3.1 + 0.1, 3.0 + 0.1, and 2.7+0.2mg with no, one, and two aspartate130 alleles). Again as for clearance, the haplotype–phenotype analysis clarified this: renal torsemide excretion with all three less frequent haplotypes was significantly different from that in carriers of the most common Asn130Val174 haplotype with 3.0+0.1, 2.5+0.2, 4.9+0.5, and 3.6+0.3mg in homozygous carriers of PERSPECTIVES

CYP2C9 polymorphisms and the interindividual variability in pharmacokinetics and pharmacodynamics of the loop diuretic drug torsemide

According to in vitro data, torsemide (INN, torasemide) is a substrate of the genetically polymorphic enzyme cytochrome P450 (CYP) 2C9, but the impact of CYP2C9 polymorphisms on torsemide pharmacokinetics and pharmacodynamics has not been studied in humans.

Relative Impact of Genotype and Enzyme Induction on the Metabolic Capacity of CYP2C9 in Healthy Volunteers

Pharmacokinetics in individual subjects is determined by genes and environment. The relative contributions of enzyme induction and inherited genomic variation to cytochrome P450 enzyme 2C9 (CYP2C9) activity are unknown. In 130 volunteers, CYP2C9 activity was measured in vivo using tolbutamide as a probe drug. Tolbutamide was administered orally, and the pharmacokinetics of the drug was analyzed twice—before and after four doses of 450 mg rifampin. Mean total apparent clearances (Cl/F) in the genotype groups CYP2C9*1/*1, *1/*2, *1/*3, *2/*3, and *3/*3 before rifampin were 0.78, 0.74, 0.52, 0.40, and 0.13 l/h, respectively. After rifampin administration, these clearances increased in all genotype groups by a median factor of 1.9 (range 1.1–4.8). The combined effects of genes and environment could be predicted by a simple additive model. Thus, enzyme induction resulted in an approximately twofold difference in CYP2C9 activity, irrespective of the CYP2C9 genotypes. But the difference in activity levels between the CYP2C9*1/*1 and *3/*3 genotypes before the administration of rifampin was sixfold.

Torasemide Transport by Organic Anion Transporters Contributes to Hyperuricemia

The high renal clearance of torasemide, the most potent loop diuretic, suggests active tubular secretion in the proximal tubule. Previous studies implicated the organic anion transporters (OAT) in this process; human OAT1 (hOAT1) and hOAT3 are found on the basolateral surface of proximal tubule

Genetic variation in the renal sodium transporters NKCC2, NCC, and ENaC in relation to the effects of loop diuretic drugs.

There is little data on genetic predictors of loop diuretic efficacy in humans. Therefore, we investigated the diuretic effects of single oral doses of bumetanide, frusemide, and torsemide in a crossover study in 97 healthy Caucasians in relation to genetic variation in the renal sodium transporters NKCC2 (coded by SLC12A1), NCC (SLC12A3), and ENaC (three subunits coded by SCNN1A, SCNN1B, and SCNN1G). The NCC alanine 264 allele (Gly264Ala) and the most frequent SCNN1B haplotype were associated with stronger diuresis, indicating lower reabsorbing function of these alleles. The variant alleles of the tightly coupled polymorphisms rs5723 (Leu649Leu) and rs5729 in SCNN1G were associated with weaker diuresis, indicating higher activity. Extended haplotype homozygosity implied evolutionary selection of the NCC alanine 264 allele. In conclusion, acute diuretic effects of loop diuretics were affected by genetic variation in sodium transporters that, in the nephron, are located distally from NKCC2.

Amelogenin-based sex identification as a strategy to control the identity of DNA samples in genetic association studies

Misassignment between DNA samples and clinical or epidemiological data may compromise the results of genetic association studies. Genotyping in replicates or controlling for Hardy-Weinberg equilibrium cannot identify misassignments caused by sample mix-ups. DNA-based sex identification (sex typing) is currently the best strategy to identify mix-ups. Here we review the available methods and present validated protocols for sex typing. The protocols are based on single-nucleotide differences between the human amelogenin genes, AMELX and AMELY, and are optimized for real-time PCR (TaqMan), primer-extension (SNaPshot) and PCR-RFLP genotyping platforms. In addition, we review the limitations of the sex-typing strategy, including a limited ability to identify single sample mix-ups, the dependence of the power of this approach on the sex distribution in the study population, and rare genetic conditions. Alternative strategies for mix-up identification and possible consequences of mix-up identification are also discussed.

Genetic variation at the CYP2C locus and its association with torsemide biotransformation

In 97 unselected volunteers and two additional homozygous carriers of CYP2C9*3, we investigated the oral clearance of torsemide in relation to 37 polymorphisms at the CYP2C gene locus. Torsemide total oral clearance was linearly associated with the number of CYP2C9*3 alleles (geometric mean: 59, 40 and 20 ml/min in carriers of no, one and two alleles) and so were the methyl- and ring-hydroxylation but not the carboxylation clearance. Haplotypes including the CYP2C9*3 allele were similarly associated with the clearances but no other variant and no haplotype not including the CYP2C9*3 variant. The extended haplotype length (EHL) of the CYP2C9 haplotypes was positively associated with higher activity of the gene product. Torsemide total oral clearance was predictable with r2=82.1% using plasma concentrations at 0.5, 1, 2 and 24 h. In conclusion, torsemides biotransformation strongly depended on the CYP2C9*3 variant but no other. Higher clearance CYP2C9 haplotypes appear to be evolutionarily selected.

Video-assisted patient education to modify behavior: A systematic review

OBJECTIVE To evaluate the efficacy of video-assisted patient education to modify behavior. METHODS Fourteen databases were searched for articles published between January 1980 and October 2013, written in English or German. Behavioral change as main outcome had to be assessed by direct measurement, objective rating, or laboratory data. RESULTS Ten of the 20 reviewed studies reported successful behavioral modification in the treatment group. We discerned three different formats to present the information: didactic presentation (objective information given as verbal instruction with or without figures), practice presentation (real people filmed while engaged in a specific practice), narrative presentation (real people filmed while enacting scenes). Seven of the ten studies reporting a behavioral change applied a practice presentation or narrative presentation format. CONCLUSION The effectiveness of video-assisted patient education is a matter of presentation format. Videos that only provide spoken or graphically presented health information are inappropriate tools to modify patient behavior. Videos showing real people doing something are more effective. PRACTICE IMPLICATIONS If researchers wish to improve a skill, a model patient enacting the behavior seems to be the best-suited presentation format. If researchers aim to modify a more complex behavior a narrative presentation format seems to be most promising.