Use of the Airstretcher with dragging may reduce rescuers' physical burden when transporting patients down stairs.

Transporting patients down stairs by carrying is associated with a particularly high fall risk for patients and the occurrence of back pain among emergency medical technicians. The present study aimed to verify the effectiveness of the Airstretcher device, which was developed to reduce rescuers' physical burden when transporting patients by dragging along the floor and down stairs. Forty-one paramedical students used three devices to transport a 65-kg manikin down stairs from the 3rd to the 1st floor. To verify the physical burden while carrying the stretchers, ratings of perceived exertion were measured using the Borg CR10 scale immediately after the task. Mean Borg CR10 scores (standard deviation) were 3.6 (1.7), 4.1 (1.8), 5.6 (2.4), and 4.2 (1.8) for the Airstretcher with dragging, Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively (p < 0.01). Multiple comparisons revealed that the Airstretcher with dragging condition was associated with significantly lower Borg CR10 scores compared with the backboard with lifting condition (p < 0.01). When the analysis was divided by handling position, estimated Borg CR10 values (standard error) for head position were 4.4 (1.3), 2.9 (0.9), 3.2 (0.8), and 4.0 (1.1) for the Airstretcher with dragging, Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively, after adjusting for participant and duration time (F = 1.4, p < 0.25). The estimated Borg CR10 value (standard error) for toe position in the Airstretcher with dragging condition was 2.0 (0.8), and the scores for the side position were 4.9 (0.4), 6.1 (0.3), and 4.7 (0.4) for the Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively, after adjusting for participant and duration time (F = 3.6, p = 0.02). Transferring a patient down stairs inside a house by dragging using the Airstretcher may reduce the physical burden for rescuers.

Growth hormone receptor gene variant and three-dimensional mandibular morphology.

OBJECTIVE: To examine the relationship between three-dimensional mandibular morphology and growth hormone receptor (GHR) gene variants in a healthy Japanese population. MATERIALS AND METHODS: The subjects, who were unrelated Japanese orthodontic patients, consisted of 64 men and 114 women. Using the Taqman genotyping assay, GHR gene rs6184 and rs6180 variants were detected in genomic DNA extracted from saliva. Mandibular volume and length were measured from cone-beam computed tomography images that were analyzed using Analyze image-processing software. The relationship between GHR gene variants and three-dimensional mandibular morphology was statistically examined. RESULTS: Statistical significance for the relationship between the distance between the left and right coronoid processes and rs6180 was noted (P < .05). CONCLUSION: Our results indicate that the GHR variant rs6180 is associated with the distance between the left and right coronoid process in the Japanese subjects.

Association of common PAX9 variants with permanent tooth size variation in non-syndromic East Asian populations.

Studies on the heredity of dental characteristics in humans have indicated that the variance in many dental traits results from genetic variation. However, the genetic factors that influence commonly occurring dental variants are poorly understood. Paired domain box 9 (PAX9) codes a transcription factor that is important in tooth development. We investigated whether PAX9 polymorphisms are associated with normal variations in tooth agenesis and morphology. The study subjects were 273 Japanese and 223 Korean adults. Single-nucleotide polymorphisms (SNPs) in PAX9 (rs2295222, rs4904155, rs2073244, rs12881240 and rs4904210) were genotyped, and third molar agenesis and mesiodistal and buccolingual diameters were measured. We found that four of the five SNPs were significantly associated with the crown size. However, no SNP was associated with third molar agenesis. In additional analyses on non-metric dental traits, we found significant associations of PAX9 SNPs with shoveling of upper first incisors. In summary, common variants in PAX9 contributed to morphological variation in permanent teeth in humans.

Effects of an Asian-specific nonsynonymous EDAR variant on multiple dental traits.

Dental morphology is highly diverse among individuals and between human populations. Although it is thought that genetic factors mainly determine common dental variations, only a few such genetic factors have been identified. One study demonstrated that a nonsynonymous single-nucleotide polymorphism (370V/A, rs3827760) in the ectodysplasin A receptor gene (EDAR) is associated with shoveling and double-shoveling grades of upper first incisors and tooth crown size. Here, we examined the association of EDAR 370V/A with several dental characters in Korean and Japanese subjects. A meta-analysis that combined analyses of Korean and Japanese subjects revealed that the Asian-specific 370A allele is associated with an increase in the grades of shoveling and double shoveling, as previously found. We also showed a highly significant association between EDAR 370V/A genotype and crown size, especially mesiodistal diameters of anterior teeth. Moreover, we found that the 370A allele was associated with the presence of hypoconulids of lower second molars. These results indicated that the EDAR polymorphism is responsible, in part, for the Sinodonty and Sundadonty dichotomy in Asian populations, and clearly demonstrated that the EDAR polymorphism has pleiotropic effects on tooth morphology. As the 370A allele is known to be a most likely target of positive selection in Asian populations, some phenotypes associated with the variant may be 'hitchhiking phenotypes', while others may be actual targets of selection.

Exome resequencing combined with linkage analysis identifies novel PTH1R variants in primary failure of tooth eruption in Japanese.

Massively parallel sequencing of target regions, exomes, and complete genomes has begun to increase the opportunities for identifying genetic variants underlying rare and common diseases dramatically. Here we applied exome resequencing to primary failure of tooth eruption (PFE) to identify the genetic causality of the disease. Two Japanese families having PFE were recruited and examined by genome-wide linkage study and subsequently exome analyses. Linkage analyses of these two families comprising eight affected individuals and two unaffected individuals revealed linkage signals at 10 loci with a maximum LOD score of 1.5. Four affected individuals in one family were pooled and further processed for exome analysis, followed by massive parallel sequencing. After three-step filtering including annotation and functional expectation, three variants were found to be candidates for PFE. Among the three variants, only a novel variant of parathyroid hormone 1 receptor gene (PTH1R), R383Q, was cosegregated in the first PFE family. Accordingly, we screened the gene for variants at all coding exons and the respective intron-exon boundaries in the second family and two sporadic individuals with PFE. We also identified a novel missense variant, P119L, cosegregating in the second family and missense variants P132L and R147C in the sporadic cases. These variants all were in the highly conserved region across zebrafish to chimpanzee and not observed in 192 unrelated controls, supporting the pathogenicity of the variants. The combination of linkage and exome analyses employed in this study provides a powerful strategy for identifying genes responsible for Mendelian disorders.

Further evidence for an association between mandibular height and the growth hormone receptor gene in a Japanese population.

INTRODUCTION: Craniofacial morphology has a significant genetic component. It has recently been reported that single nucleotide polymorphisms (SNPs) in the growth hormone receptor gene (GHR) are associated with mandibular height. To confirm these findings, we genotyped SNPs in healthy Japanese subjects, about 1.7 times the number analyzed in previous reports. METHODS: By using 5 SNPs in exon 10 of the GHR, we studied the relationships between genotypes and craniofacial linear measurements. The allelic frequencies in a multi-ethnic population (Han Chinese, African American, European American, and Hispanic) were also observed. RESULTS: There was a significant association between SNPs and mandibular ramus height (P = 0.029), confirming our previous report of an association between polymorphism P561T and mandibular ramus height. Moreover, the SNP, C422F, was in linkage disequilibrium with P561T. Subjects with genotype CC of polymorphism P561T and genotype GG of polymorphism C422F had significantly greater mandibular ramus height than those with genotypes CA and GT. Four of the 5 SNPs were found almost exclusively in Asians, with the frequencies in other populations extremely small. CONCLUSIONS: Our results indicate that the GHR polymorphisms P561T and C422F are associated with mandibular ramus height in Japanese population and suggest that the SNPs of the GHR associated with the Japanese are likely to be different in other ethnic groups. This might partly explain the differing craniofacial morphology among different ethnicities.

Association of the growth hormone receptor gene polymorphisms with mandibular height in a Korean population.

Growth hormone receptor gene (GHR) is one of the likely candidates for determining morphological traits, because GH is a key regulator of bone growth. The genetic association of GHR in exon 10 with mandibular ramus height has been found in different populations, Japanese and Chinese. On the other hand, two common isoforms of GHR, one full-length (fl-GHR) and the other lacking the extracellular domain encoded by exon 3 (d3-GHR), are associated with differences in responsiveness to GH. The purpose of this study involving 159 Korean subjects was to study the associations between a GHR polymorphism (d3/fl-GHR) that results in genomic deletion of exon 3 and craniofacial morphology, and to study the associations between GHR genotypes in exon 10 and craniofacial morphology. Moreover, the allelic frequencies in a multi-ethnic population (24 Han Chinese, 24 African-Americans, 24 European-Americans, and 24 Hispanics) in a GHR polymorphism (d3/fl-GHR) were compared in this study. The five craniofacial linear measurements (cranial base length, maxillary length, overall mandibular length, mandibular corpus length, and mandibular ramus height) obtained from lateral cephalograms were examined as craniofacial morphology. We found that the d3/fl-GHR polymorphism had no association for any measurements, and a statistically significant association (P=0.024) between the GHR polymorphisms P561T and C422F in exon 10 and mandibular ramus height. Neither SNPs besides P561T and C422F polymorphisms in exon 10 nor the measurements besides mandibular ramus height have statistically significances. Both derived alleles at P561T and C422F SNPs were highly associated with only one haplotype, haplotype-4 in Korean population. As quantitative haplotype association, the results showed a significant difference in mandibular ramus height between individuals having one haplotype-4 and others without haplotype-4 (P=0.028). Moreover, we found that the d3/fl-GHR polymorphism showed diverse frequency in different population. Regarding GHR genotypes in exon 10, the present study mostly reflected the results obtained for a Japanese population, although our current study does not replicate the correlation between the I526L polymorphism of GHR and mandibular ramus height as was reported in a previous study of Han Chinese. The results of the present study suggest that the GHR exon 10 SNPs, not d3/fl-GHR, contribute to changes in the mandibular ramus height of Koreans.

Allergy as a possible predisposing factor for hypodontia.

The aim of this retrospective study was to identify general health problems as potential predisposing factors for hypodontia in a population of Japanese orthodontic patients. The study included 3683 individuals (1312 males and 2371 females, 13-42 years of age; mean, 23 years 7 months). Dental pantomograms (DPTs) were used to diagnose hypodontia. Health histories were obtained through a questionnaire administered by the dentist in charge. The Mantel-Haenszel test was used to determine the significance of the differences in the prevalence of health problems. The overall frequency of hypodontia was 5.8 per cent. The average number of missing teeth per patient was 1.7. There was a high prevalence of systemic complications, which included allergy, asthma, atopy, and enlarged adenoids associated with hypodontia. Only allergy showed a significant relationship with hypodontia (P < 0.01). The environmental aetiology of hypodontia is not yet fully understood. However, based on the results of this retrospective study, predisposing general health problems, especially allergy, seem to be involved.