Quantitative trait locus on chromosome X affects bone loss after maturation in mice.

Genetic programming is known to affect the peak bone mass and bone loss after maturation. However, little is known about how polymorphic genes on chromosome X (Chr X) modulate bone loss after maturation. We previously reported a quantitative trait locus (QTL) on Chr X, designated Pbd3, which had a suggestive linkage to bone mass, in male SAMP2 and SAMP6 mice. In this study, we aimed to clarify the effects of Pbd3 on the skeletal phenotype. We generated a congenic strain, P2.P6-X, carrying a 45.6-cM SAMP6-derived Chr X interval on a SAMP2 genetic background. The effects of Pbd3 on the bone phenotype were determined by microcomputed tomography (microCT), whole-body dual-energy X-ray absorptiometry (DXA), serum bone turnover markers, and histomorphometric parameters. Both the bone area fraction (BA/TA) on microCT and whole-body DXA revealed reduced bone loss in P2.P6-X compared with that in SAMP2. The serum concentrations of bone turnover markers at 4 months of age were significantly lower in P2.P6-X than in SAMP2, but did not differ at 8 months of age. These results were observed in female mice, but not in male mice. In conclusion, a QTL within a segregated 45.6-cM interval on Chr X is sex-specifically related to the rate of bone loss after maturation.

Quantitative trait locus that determines the cross-sectional shape of the femur in SAMP6 and SAMP2 mice.

UNLABELLED: We segregated a QTL on chromosome 11 that affects femoral cross-sectional shape during growth by generating a congenic strain and an additional 16 subcongenic strains of the senescence-accelerated mouse strain, SAMP6. The QTL region was narrowed down to a 10.0-Mbp region. INTRODUCTION: Genetic background is known to affect bone characteristics. However, little is known about how polymorphic genes modulate bone shape. In a previous study using SAMP2 and SAMP6 mice, we reported a quantitative trait locus (QTL) on chromosome (Chr) 11 that had significant linkage to peak relative bone mass in terms of cortical thickness index (CTI) in male mice. We named it Pbd1. Here we aimed to clarify the effects of Pbd1 on skeletal phenotype in male mice and to narrow down the QTL region. MATERIALS AND METHODS: We generated a congenic strain named P6.P2-Pbd1(b), carrying a 39-cM SAMP2-derived Chr11 interval on a SAMP6 genetic background. Sixteen subcongenic strains with smaller overlapping intervals on the SAMP6 background were generated from P6.P2-Pbd1(b) to narrow the region of interest. The effects of Pbd1 on bone properties were determined. Gene expression analysis of all candidate genes in Pbd1 was performed using real-time RT-PCR. RESULTS: The CTI of strain P6.P2-Pbd1(b) at 16 wk was higher than that of SAMP6. This was not caused by differences in cortical thickness but by cross-sectional shape. Morphological analysis by microCT revealed that the femoral cross-sectional shape of P6.P2-Pbd1(b) (and the other subcongenic strains with higher CTI or bone area fraction [BA/TA]) was more compressed anteroposteriorly than that of SAMP6, which was associated with superior mechanical properties. This feature was formed during bone modeling up to 16 wk of age. Subcongenic strains with a higher CTI showed significant increases in endocortical mineral apposition rate and significant reductions in periosteal mineral apposition rate at 8 wk compared with those of the SAMP6. The Pbd1 locus was successfully narrowed down to a 10.0-Mbp region, and the expression analysis suggested a candidate gene, Cacng4. CONCLUSIONS: The Pbd1 affects femoral cross-sectional shape by regulating the rate of endocortical and periosteal bone formation of the femur during postnatal growth.

Detection of dexmedetomidine in human breast milk using liquid chromatography-tandem mass spectrometry: Application to a study of drug safety in breastfeeding after Cesarean section.

Several analytical methods for dexmedetomidine (DEX) in human plasma have been published, but quantification of DEX in human breast milk has not been described. In this article, we describe a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method suitable for quantification of DEX in human breast milk. DEX and an internal standard were extracted in a single liquid-liquid extraction step with diethyl ether from 200µL of human breast milk. HPLC was performed on a TSK-gel ODS-100V column with isocratic elution at a flow rate of 0.3mL/min using a mobile phase of 5mM ammonium formate:0.1% formic acid in acetonitrile (60:40, v/v). Detection was performed using an API4000 mass spectrometer with positive electrospray ionization. The method was validated in the concentration range of 10pg/mL (lower limit of quantification) to 2000pg/mL. The intra- and inter-day accuracy were within ±5.8% and precision was <6.31% based on the coefficient of variation. The recoveries of DEX in human breast milk were 82.4-87.9%. Recovery and matrix effects were consistent and reproducible for human breast milk. The method is robust and was successfully used in a study of drug safety in breastfeeding in patients after administration of DEX.

Secreted frizzled-related protein 4 is a negative regulator of peak BMD in SAMP6 mice.

UNLABELLED: We segregated a QTL for peak BMD on Chr 13 by generating congenic sublines of the senescence-accelerated mouse SAMP6. Sfrp 4 within this locus was responsible for lower BMD of SAMP6. INTRODUCTION: Our genome-wide linkage study using SAMP6 and SAMP2 showed a significant quantitative trait locus (QTL) for peak BMD on chromosome (Chr) 13. To verify the gene that regulates peak BMD, we generated a congenic strain, P6.P2-Pbd2(b), which carried a 15-cM SAMP2 interval on an osteoporotic SAMP6 background, and showed that this Pbd2 locus increased peak BMD in SAMP6. MATERIALS AND METHODS: To narrow down this interval, we generated a new congenic subline P6.P2-13. We studied the effect of this locus on morphological and histomorphological features in vivo and on osteoblasts in vitro. The levels of expression of all genes in the segregated interval were examined, and we clarified the effect of the candidate gene, secreted frizzled-related protein (Sfrp4), on osteoblasts in vitro. RESULTS: The new congenic strain, P6.P2-13, retained the 2.4-Mb SAMP2 interval on the SAMP6 background, and 11 genes existed in this interval. In morphometrical analysis, P6.P2-13 increased the bone area fraction (BA/TA) by 6.6% at the diaphysial cortex (p < 0.001) and increased the trabecular bone volume (BV/TV) by 54.2% at the distal metaphysis (p < 0.05) in the femora compared with those of SAMP6. The bone formation rate of P6.P2-13 was markedly increased at the periosteal surface of femoral cortex and that was caused by a higher proliferation rate of osteoblasts in P6.P2-13 compared with those in SAMP6. Quantitative RT-PCR analysis of calvaria tissue showed approximately 40-fold higher levels of expression of Sfrp4 in SAMP6 than in P6.P2-13. Taken together with the result that recombinant Sfrp4 suppressed the proliferation of osteoblasts, we hypothesized that Sfrp4 inhibited the proliferation of osteoblasts through its antagonistic effect on Wnt signaling. TCF/beta-catenin-dependent reporter activity in osteoblasts derived from SAMP6 showed lower responsiveness for the Wnt ligand, Wnt3A, than that in osteoblasts from P6.P2-13. CONCLUSIONS: In SAMP6 mice, Sfrp4 negatively regulates bone formation and decreases BMD through the inhibition of Wnt signaling.

Clinical trials for drug approval: a pilot study of the view of doctors at Tokushima University Hospital.

The development of new and useful pharmaceutical drugs is essential in order to improve the quality of drug therapeutics. Clinical trials play a central role in drug development. Over time, the clinical trial infrastructure has improved and is now integrating the contribution of clinical research coordinators (CRC). Nevertheless, the attitude of doctors towards clinical trials still favors conventional/historical methodologies. In the present study, we explored the view of doctors towards clinical trials for drug development, in order to improve communication among participants, sponsors, and investigators.A questionnaire was designed for this pilot study. The questionnaire included general attitudes, difficult points, the benefit of doctors in participating as investigators, special attention requirements, and the expected role of CRC in clinical trials for drug approval. In addition, the appropriate use of the outpatient clinic was examined. The questionnaire was provided to doctors in each department of Tokushima University Hospital in 2000 and 2004. Because of the small number of subjects included in this pilot study, no statistical analysis is presented. A total of 89 (81%) and 62 (56%) doctors among 110 responded to the survey in 2000 and 2004, respectively. Inquiries about the familiarity of the physicians with clinical trials for drug approval revealed that 84% in 2000 and 66% in 2004 were aware of such trials. The attitude towards participating as investigators in the clinical trials was favorable, with a response of 66% in 2000 and 58% in 2004. Patients' refusal and the informed consent process were considered difficult areas by many doctors. Expected roles of CRC included activities based on the nurse's specialty. Although many doctors agreed to take care of the study participants separately from the clinical practice, they lacked the time to do so. In spite of the doctors' workload reduction by introduction of the CRC concept, their views regarding clinical trials for drug approval remain conventional. Further refinement in the support process by CRC should be considered in our hospital, and the views of the doctors should be investigated in a larger study, in order to promote clinical trials for drug approval in Japan.

Osteoblast-targeted expression of Sfrp4 in mice results in low bone mass.

UNLABELLED: Transgenic mice overexpressing Sfrp4 in osteoblasts were established. These mice exhibited low bone mass caused by a decrease in bone formation. INTRODUCTION: We recently reported that single nucleotide polymorphisms in the secreted frizzled-related protein 4 (Sfrp4) gene are responsible for low peak BMD in senescence-accelerated mouse (SAM) P6. In vitro studies revealed inhibition of osteoblast proliferation by Sfrp4, which is supposed to be mediated by canonical Wnt signaling. MATERIALS AND METHODS: We examined the expression of Sfrp4 in neonate long bones by in situ hybridization and generated transgenic mice in which Sfrp4 was specifically overexpressed in osteoblasts under the control of a 2.3-kb Col1a1 osteoblast-specific promoter. Next, we compared the phenotype of Sfrp4 transgenic (Sfrp4 TG) mice with that of mice in which one allele of beta-catenin was conditionally disrupted in osteoblasts (betaChet), and administered lithium chloride (LiCl) to Sfrp4 TG mice. RESULTS: Hemizygous Sfrp4 TG mice exhibited a 30% reduction of trabecular bone mass compared with that in wildtype littermates at 8 wk of age, and histomorphometrical analysis showed decreases in both osteoblast numbers and bone formation rate. betaChet mice exhibited a 17% reduction of trabecular bone mass in distal femora caused by an increase in the osteoclast number and a decrease in bone formation rate. Furthermore, LiCl administration rescued the bone phenotype of Sfrp4 TG mice. CONCLUSIONS: Expression of Sfrp4 in periosteum and bone tissues suggested the role of Sfrp4 in osteoblasts, and we identified that overexpression of Sfrp4 in osteoblasts suppressed osteoblast proliferation, resulting in a decrease in bone formation in vivo. Partial suppression of beta-catenin/canonical Wnt signaling also impaired bone formation, and activation of the signaling restored low bone mass of Sfrp4 TG mice. Thus, these results indicate that Sfrp4 decreases bone formation at least in part by attenuating canonical Wnt signaling in vivo.

Role of clinical research coordinators in promoting clinical trials of drugs for surgical patients.

BACKGROUND: Clinical trials play a central role in the establishment of clinical evidence, and the important role of clinical research coordinators (CRCs) in various processes of clinical trials is now widely recognized. In Japan, many CRCs work under the discretion of their hospital and support clinical trials in various areas. Modification of CRC activity pursuant to the types of clinical trials may make roles of the CRC more effective and meaningful. In the present study, we examine the dedicated role of the CRC considering the specialty of a registration trial of a drug for surgical patients used during the operation period. METHODS: In 2006, we had a chance to support a registration trial of a drug for surgical patients used during the operation period. Regarding the mental and emotional status of possible participants in the present registration trial, we collected data from the perspective of CRCs by focus group interviews involving four CRCs working under the discretion of Tokushima University Hospital. The four CRCs were all nurses and had 7, 4.5, 1, or 0.5 years experience as CRCs, respectively. RESULTS: In contrast to clinical trials of drugs for chronic diseases, these often anxious patients must decide whether or not to enter the trial simultaneously with the decision to undergo surgery itself, and all in a relatively limited time after receiving explanation of the trial. Therefore, special attention should be paid to the mental and emotional status of possible participants. Additionally, the cooperation of the relatively large surgical and nursing staff becomes important. In such situations, the following contributions of CRCs were considered to be useful for the harmonious procedure of clinical trials: 1) providing a precise explanation of the trial to the participant and key persons, 2) understanding the needs of the investigators and appropriately assigning themselves roles, and 3) communicating between the investigators and surgical and nursing staff. CONCLUSION: Further study is warranted to evaluate the benefit of the intervention provided by dedicated CRCs in running high quality clinical trials involving surgical patients.