Degree of biological apatite c‐axis orientation rather than bone mineral density controls mechanical function in bone regenerated using recombinant bone morphogenetic protein‐2

The aim of the present study was to assess the bone regeneration process in defects introduced into rabbit long bones, which were regenerated with controlled release of recombinant bone morphogenetic protein‐2 (rBMP‐2). The orientation of the biological apatite (BAp) c‐axis and bone mineral density (BMD) were compared as predictors of bone mechanical function. A 20‐mm‐long defect was introduced in rabbit ulnas, and 17 µg of rBMP‐2 was controlled‐released into the defect using a biodegradable gelatin hydrogel as the carrier. In the bone regeneration process, two characteristic phases may have been governed by different factors. First, new bone formation actively occurred, filling the bone defect with newly formed bone tissue and increasing the BMD. This process was regulated by the strong osteoinductive capacity of rBMP‐2. Second, after filling of the defect and moderate BMD restoration, preferential BAp c‐axis orientation began to increase, coincident with initiation of remodeling. In addition, the BAp c‐axis orientation, rather than BMD, was strongly correlated with Young's modulus, an important index of bone mechanical function, particularly in the later stage of bone regeneration. Thus, preferential BAp c‐axis orientation is a strong determinant and predictor of the mechanical function of tissue‐engineered bone. Therefore, analysis of BAp preferential c‐axis orientation in addition to measurement of BMD is crucial in assessment of bone mechanical function. © 2013 American Society for Bone and Mineral Research © 2013 American Society for Bone and Mineral Research     

Hepatocyte growth factor stimulates root growth during the development of mouse molar teeth

Sakuraba H, Fujiwara N, Sasaki‐Oikawa A, Sakano M, Tabata Y, Otsu K, Ishizeki K, Harada H. Hepatocyte growth factor stimulates root growth during the development of mouse molar teeth. J Periodont Res 2012; 47: 81–88. © 2011 John Wiley & Sons A/S Background and Objective: It is well known that tooth root formation is initiated by the development of Hertwig’s epithelial root sheath (HERS). However, relatively little is known about the regulatory mechanisms involved in root development. As hepatocyte growth factor (HGF) is one of the mediators of epithelial–mesenchymal interactions in rodent tooth, the objective of this study was to examine the effects of HGF on the root development of mouse molars. Material and Methods: The HERS of mouse molars and HERS01a, a cell line originated from HERS, were used in this study. For detection of HGF receptors in vivo and in vitro, we used immunochemical procedures. Root development was assessed by implanting molar tooth germs along with HGF‐soaked beads into kidney capsules, by counting cell numbers in HERS01a cell cultures and by performing a 5′‐bromo‐2′‐deoxyuridine (BrdU) assay in an organ‐culture system. Results: HGF receptors were expressed in the enamel epithelium of molar germs as well as in HERS cells. HGF stimulated root development in the transplanted tooth germs, the proliferation of HERS01a cells in culture and HERS elongation in the organ‐culture system. Examination using BrdU revealed that cell proliferation in HERS was increased by treatment with HGF, especially that in the outer layer of HERS. This effect was down‐regulated when antibody against HGF receptor was present in the culture medium. Conclusion: Our results raise the possibility that HGF signaling controls root formation via the development of HERS. This study is the first to show that HGF is one of the stimulators of root development.     

Increased parietal activity after training of interference control

Recent studies suggest that computerized cognitive training leads to improved performance in related but untrained tasks (i.e. transfer effects). However, most study designs prevent disentangling which of the task components are necessary for transfer. In the current study, we examined whether training on two variants of the adaptive dual n-back task would affect untrained task performance and the corresponding electrophysiological event-related potentials (ERPs). Forty three healthy young adults were trained for three weeks with a high or low interference training variant of the dual n-back task, or they were assigned to a passive control group. While n-back training with high interference led to partial improvements in the Attention Network Test (ANT), we did not find transfer to measures of working memory and fluid intelligence. ERP analysis in the n-back task and the ANT indicated overlapping processes in the P3 time range. Moreover, in the ANT, we detected increased parietal activity for the interference training group alone. In contrast, we did not find electrophysiological differences between the low interference training and the control group. These findings suggest that training on an interference control task leads to higher electrophysiological activity in the parietal cortex, which may be related to improvements in processing speed, attentional control, or both.     

Immunohistochemical changes related to ageing in the mouse hippocampus and subventricular zone

We investigated mainly immunohistochemical changes of nestin (a marker of neuroepithelial stem cells) and Ki-67 (a marker of proliferating cells) proteins related to ageing in the mouse hippocampus and subventricular zone (SVZ) using young adult (8 weeks old) and middle-aged (40 weeks old) mice. In the present study, no significant changes in neurons and astrocytes of the hippocampal CA1 sector were found in a middle-aged male ICR mice without severe senile weakness, as compared with young adult animals. In contrast, a significant change in the number of microglia was found in the hippocampal CA1 sector of the middle-aged mice. Furthermore, no significant changes in the number of nestin- and Ki-67-positive cells were observed in the hippocampal CA1 sector of the middle-aged mice. On the other hand, decreases in the number of nestin- and Ki-67-immunopositive cells were observed in the SVZ of the middle-aged mice. Furthermore, a migration of nestin- and Ki-67-immunoreactive cells in the corpus callosum was not observed in the SVZ of the middle-aged mice. In the dentate gyrus, significant decreases in the number of Ki-67-immunopositive cells were observed in the middle-aged mice. Our study also showed that nestin immunoreactivity was observed in both Ki-67-postive cells and astrocytes in the SVZ of young adult mice. These findings emphasize the need to recognize ageing as important factors in studies of microglia, which may help to clarify the role of glial cell structure and function during ageing processes. Furthermore, the present findings suggest that ageing processes may decrease neurogenesis in the corpus callosum, SVZ and dentate gyrus. Thus our present findings provide valuable information for the neurogenesis during ageing processes.     

Evaluating a single dental anxiety question in Finnish adults

OBJECTIVE: To evaluate the psychometric properties (criterion validity, construct validity, sensitivity, and specificity) of a single-item question screening for dental anxiety in a Finnish adult population. MATERIAL AND METHODS: A total of 823 subjects, ranging in age from 18 to 87 years, answered a questionnaire comprising sections assessing the respondents' demographic profile and dental attendance patterns. A single dental anxiety question and the Modified Dental Anxiety Scale (MDAS) were included. The final response rate was 85%. RESULTS: Eight percent of the sample was highly dentally anxious using the MDAS cut-off point of 19 or above. Twelve percent of the respondents rated themselves as "very scared" on the single-item question. The percentage agreement between the single-item question and the MDAS was 93; the Kappa coefficient was 0.63. Specificity of the single question was 0.95 while sensitivity was 0.80 using the MDAS dichotomous classification. The single-item question related to age (p<0.001), gender (p<0.001), and dental attendance (p<0.001), as predicted. CONCLUSIONS: The single question has good validity, specificity, and sensitivity and may be used with confidence to assess dental fear in such situations as national health surveys or in routine dental practice where a multi-item dental anxiety questionnaire is not feasible.     

Distinct intraspecific variations of garlic (Allium sativum L.) revealed by the exon–intron sequences of the alliinase gene

Garlic (Allium sativum L.) has been used worldwide as a food and for medicinal purposes since early times. Garlic cultivars exhibit considerable morphological diversity despite the fact that they are mostly sterile and are grown only by vegetative propagation of cloves. Considerable recombination occurs in garlic genomes, including the genes involved in secondary metabolites. We examined the genomic DNAs (gDNAs) from garlic, encoding alliinase, a key enzyme involved in organosulfur metabolism in Allium plants. The 1.7-kb gDNA fragments, covering three exons (2, 3, and 4) and all four introns, were amplified from total DNAs prepared from garlic samples produced in Asia and Europe, leading to 73 sequences in total: Japan (JPN), China (CHN), India (IND), Spain (ESP), and France (FRA). The exon sequences were highly conserved among all the sequences, probably reflecting the fully functional alliinase associated with the flavor quality. Distinct intraspecific variations were detected for all four intron sequences, leading to the haplotype classifications. A close relationship between JPN and CHN was observed for all four introns, whereas IND showed a more divergent distribution. ESP and FRA afforded clearly different variants compared with those from Asian sequences. The present study provides information that could be useful in the development of an additional molecular marker for garlic authentication and quality control.