Mechanism of motor coordination of masseter and temporalis muscles for increased masticatory efficiency in mice

The demand for the use of mice as animal models for elucidating the pathophysiologies and pathogeneses of oral motor disorders has been increasing in recent years, as more and more kinds of genetically modified mice that express functional disorders of the stomatognathic system become available. However, the fundamental characteristics of mouse jaw movements during mastication have yet to be fully elucidated. The purpose of this study was to investigate the roles of the masseter and temporalis muscles, and the mechanisms of motor coordination of these muscles for increasing masticatory efficiency in the closing phase in mice. Twenty-two male Jcl:ICR mice were divided into control (n = 8), masseter-hypofunction (n = 7) and temporalis-hypofunction groups (n = 7). Botulinum neurotoxin type A (BoNT⁄A) was used to induce muscle hypofunction. The masticatory movement path in the horizontal direction during the occlusal phase became unstable after BoNT⁄A injection into the masseter muscle. BoNT⁄A injection into the temporalis muscle decreased antero-posterior excursion of the late-closing phase corresponding to the power phase of the chewing cycle. These results suggest that the masseter plays an important role in stabilizing the grinding path, where the food bolus is ground by sliding the posterior teeth from back to front during the occlusal phase. The temporalis plays a major role in retracting the mandible more posteriorly in the early phase of closing, extending the grinding path. Masticatory efficiency is thus increased based on the coordination of activities by the masseter and temporalis muscles.

Impact of renal transplantation on glucose tolerance in Japanese recipients with impaired glucose tolerance

AIMS

To investigate changes in glucose tolerance, insulin secretion and insulin sensitivity in Japanese recipients before and 1 year after renal transplantation.

METHODS

We conducted a study of Japanese recipients without diabetes who underwent renal transplantation at Hokkaido University Hospital. A 75-g oral glucose tolerance test was performed before and 1 year after renal transplantation in these recipients. Insulin sensitivity was estimated using the Matsuda index and homeostasis model assessment of insulin resistance (HOMA-IR). Insulin secretion was evaluated based on the insulin secretion sensitivity index-2 (ISSI-2).

RESULTS

Of the 62 renal transplant recipients, 31 were diagnosed as having impaired glucose tolerance before transplantation. Among these 31 recipients, after 1 year, four had developed new-onset diabetes after transplantation, and nine had impaired glucose tolerance. Unexpectedly, 18 changed from impaired to normal glucose tolerance. When these recipients with impaired glucose tolerance were classified into a non-amelioration group and an amelioration group, the ISSI-2 was significantly reduced, with no significant changes in the Matsuda index or HOMA-IR, in the non-amelioration group 1 year after renal transplantation. By contrast, ISSI-2 and Matsuda index values were significantly increased, with no significant changes in HOMA-IR values in the amelioration group.

CONCLUSIONS

More than half of Japanese renal transplant recipients with impaired glucose tolerance had normal glucose tolerance 1 year after renal transplantation. These results suggest that an increase in insulin secretion and whole insulin sensitivity was associated with improvement in glucose tolerance in these recipients.

Electron and lattice dynamics of transition metal thin films observed by ultrafast electron diffraction and transient optical measurements

We report the ultrafast dynamics of electrons and lattice in transition metal thin films (Au, Cu, and Mo) investigated by a combination of ultrafast electron diffraction (UED) and pump-probe optical methods. For a single-crystalline Au thin film, we observe the suppression of the diffraction intensity occuring in 10 ps, which direcly reflects the lattice thermalization via the electron-phonon interaction. By using the two-temperature model, the electron-phonon coupling constant (g) and the electron and lattice temperatures (Te, Tl) are evaluated from UED, with which we simulate the transient optical transmittance. The simulation well agrees with the experimentally obtained transmittance data, except for the slight deviations at the initial photoexcitation and the relaxed quasi-equilibrium state. We also present the results similarly obtained for polycrystalline Au, Cu, and Mo thin films and demonstrate the electron and lattice dynamics occurring in metals with different electron-phonon coupling strengths.

Spontaneous Eosinophilic Granulated Round Cell Tumors in Rats

Morphologic and histochemical characteristics were noted for three spontaneous tumors with eosinophilic cytoplasmic granules that occurred in aged Fischer 344 rats. Macroscopic lesions were widely distributed in the body, mainly involving the intra-abdominal adipose tissue, pancreas, and mesenterium. These lesions were generally hard swellings with nodular and sclerosing areas. Bloody ascites was a concomitant finding. Histologically, the tumor cells were round, from 9 to 30 μm in diameter with one or two round to oval nuclei, and characterized by eosinophilic granules (0.5–2.0 μm) that stained definitely to weakly positive with the periodic acid-Schiff reaction and demonstrated no metachromasia with toluidine blue stain. Furthermore, the granules were characterized by a positive reaction with lectin histochemistry for concanavalin A (Con A), wheat germ agglutinin (WGA), phaseolus vulgaris agglutinin (PHA-E4), lens culinaris agglutinin (LCA), and recinus communis agglutinin (RCA-I) in all tumors and for ulex europaeus agglutinin (UEA-I), peanut agglutinin (PNA), and soybean agglutinin (SBA) in one tumor. Positive reactions for anti-rat mast cell protease II and CD8 were not demonstrated immunohistochemically. Abundant glycogen was noted in the large tumor cells from one rat. With electron microscopy, the cytoplasmic granules were identified as electron-dense homogenous bodies bounded by a single unit membrane. These characteristics are similar to those of granulated metrial gland cells, but further study is needed to clarify the cell of origin for these tumors.

Elevational sensitivity in an Asian 'hotspot': moth diversity across elevational gradients in tropical, sub-tropical and sub-alpine China

South-western China is widely acknowledged as a biodiversity ‘hotspot’: there are high levels of diversity and endemism, and many environments are under significant anthropogenic threats not least climate warming. Here, we explore diversity and compare response patterns of moth assemblages among three elevational gradients established within different climatic bioregions - tropical rain forest, sub-tropical evergreen broad-leaved forest and sub-alpine coniferous forest in Yunnan Province, China. We hypothesised that tropical assemblages would be more elevationally stratified than temperate assemblages, and tropical species would be more elevationally restricted than those in the temperate zone. Contrary to our hypothesis, the moth fauna was more sensitive to elevational differences within the temperate transect, followed by sub-tropical and tropical transects. Moths in the cooler and more seasonal temperate sub-alpine gradient showed stronger elevation-decay beta diversity patterns, and more species were restricted to particular elevational ranges. Our study suggests that moth assemblages are under threat from future climate change and sub-alpine rather than tropical faunas may be the most sensitive to climate change. These results improve our understanding of China’s biodiversity and can be used to monitor future changes to herbivore assemblages in a ‘hotspot’ of biodiversity.

Predictors of obstructive sleep apnoea-hypopnea severity and oral appliance therapy efficacy by using lateral cephalometric analysis

Obstructive sleep apnoea-hypopnea (OSAH) is a common disorder characterised by repetitive complete or partial closure of the upper airway during sleep, which results in sleep fragmentation and oxygen desaturation. There is growing interest in the use of oral appliances (OAs) to treat OSAH. The purpose of this study was to clarify the cephalometric factors that are associated with OSAH severity and that predict the outcome of OA therapy. Two hundred nine patients with OSAH were recruited and analysed retrospectively. They had a polysomnographically documented apnoea-hypopnea index (AHI) of more than five respiratory events per hour. Lateral skull radiographs were used for cephalometric analysis. Only 67 of the 209 recruited patients underwent a second polysomnography (PSG) to evaluate the efficacy of OA therapy. In all recruited patients, the angle formed by the subspinal point (A) to the nasion (N) to the supramental point (B) (i.e. ANB angle) and the distance between the mandibular plane and hyoid bone (MP-H) were predictive factors of OSAH severity. In only 67 patients underwent PSG with an OA, the mean rate of decrease in the AHI was 47·8 ± 29·1%. OA therapy effectively treated OSAH in some patients with a very severe form of OSAH. However, patients who had a high position of the hyoid bone had a poor response to OA therapy. This study suggested that cephalometric analysis is useful for predicting OSAH severity and OA therapy efficacy.

Cytogenetic dosimetry by micronucleus assay using peripheral blood cells is modified by thyroid hormones

Cytokinesis-block micronucleus (CBMN) assay is a convenient and easy method of radiation biodosimetry that uses peripheral blood (PB) cells. However, for micronuclei (MN) frequency induced by ionising radiation, a dose-response relationship in abnormal condition, such as in cancer patients, has not been assessed. To clarify the difference between the dose-response curve generated by the CBMN assay in conditions when thyroid hormone levels were normal and during thyroid hormone withdrawal (THW) prior to (131)I treatment, 12 thyroid cancer patients who underwent thyroidectomy were studied. The collected PB mononuclear cells were exposed to 0.5-3.0 Gy X-ray irradiation. Under normal conditions, dose dependency and independency of MN frequency were observed in 92 % and 8 %, respectively. In contrast, during THW, the number of patients who showed dose independency significantly increased to 42 % in comparison with control. Furthermore, a higher concentration of serum thyroglobulin in dose-independent patients was observed. These results suggest that MN frequency in cytogenetic dosimetry is affected by thyroid hormones.