Mitsuhiko Morito

Protective Effect of Lecithinized SOD on Reactive Oxygen Species-Induced Xerostomia

Abstract Reactive oxygen species (ROS) are believed to be involved in radiation-induced xerostomia, and the application of antioxidants may be a promising method for treating patients suffering from salivary gland dysfunction. In this study, we examined the ability of the antioxidant superoxide dismutase (SOD) to restore radiation-induced salivary gland dysfunction using a mouse model of radiation-induced salivary gland hypofunction and ultraviolet B (UVB)-irradiated human salivary gland cells. We administered lecithinized SOD (PC-SOD) prior to and after irradiation and measured the amount of saliva secreted. To confirm ROS generation, flow cytometry was performed using an oxidant-sensitive fluorescent dye, dihydroethidium, and CM-H2DCFDA. While no significant decrease in saliva secretion was observed after irradiation in the mice that were treated with PC-SOD, a significant reduction in saliva secretion was noted in the irradiated mice that were not treated with PC-SOD. Furthermore, flow cytometry clearly revealed that PC-SOD eliminated superoxide (O2−) induced by UVB radiation. These results suggested that PC-SOD may protect against exocrine gland dysfunction induced by radiation, presumably by rapidly converting O2− to hydrogen peroxide. We believe that our results may advance the potential application of antioxidants for the prevention of ROS-induced xerostomia.

Autophagic-lysosomal pathway functions in the masseter and tongue muscles in the klotho mouse, a mouse model for aging.

Klotho mutant (kl/kl) mice, a type of short-lived mouse models, display several aging-related phenotypes. To investigate whether the atrophy of skeletal muscles is induced in these mice via activation of the ubiquitin–proteasomal pathway and/or the autophagic-lysosomal pathway through an alteration of insulin/IGF-I signaling, we analyzed the activity of the two pathways for protein degradation and components of the insulin/IGF signaling pathway in their skeletal muscles. The masseter, tongue, and gastrocnemius muscles in kl/kl showed marked reductions in muscle weight and in myofiber diameter compared with +/+. The autophagic-lysosomal pathway in kl/kl was activated in the masseter and tongue, but not in the gastrocnemius, compared with that in +/+, whereas the ubiquitin–proteasomal pathway in these three muscles of kl/kl was not altered. No marked difference in the phosphorylation levels of insulin/IGF-I signaling components, such as insulin/IGF-I receptor, Akt, and FoxO in three muscles studied were found between kl/kl and +/+, but the phosphorylation levels of signaling component at the downstream of mTOR such as 4E-BP1 and p70 S6K were suppressed in the masseter and tongue of kl/kl compared with +/+. Deficiency of essential amino acids is reported to activate the autophagy-lysosomal pathway through the down-regulation of mTOR, not through IGF–Akt-FoxO. The masseter and tongue seem to be more actively moved than limb muscles in kl/kl, because they are essential for survival activities such as mastication, swallowing, and respiration. Thus, the deficiency of amino acid by the active movement of the masseter and tongue seems to stimulate the autophagic-lysosomal pathway via the down-regulation of mTOR signalling pathway.

Changes in Triacylglycerol‐Accumulated Fiber Type, Fiber Type Composition, and Biogenesis in the Mitochondria of the Soleus Muscle in Obese Rats

Little is known about the effects of obesity on skeletal muscle consisting of approximately 80% type I (slow) fibers, such as that in the soleus muscle, although type I fibers have an enhanced capacity for mitochondrial respiration and fatty acid oxidation. We investigated the effects of obesity on the soleus muscle in the rat. Rats were fed a high‐fat diet (protein:fat:carbohydrate = 20:57:23; 508 kcal/100 g) or a control diet (protein:fat:carbohydrate = 20:10:70; 366 kcal/100 g) for 10 weeks. We analyzed the accumulation of intramyocellular triacylglycerol (IMTG), fiber type composition, and the biogenesis and function of the mitochondria in the soleus muscle of the rat during 10 weeks of feeding, using histochemical and real‐time polymerase chain reaction analyses. Obesity increased body weight and markedly elevated IMTG levels in type I, but not in type II, fibers of the soleus muscle throughout the feeding period. Obesity also inhibited the biogenesis and function in the mitochondria and altered the fiber type composition in the soleus muscle. The suppression of biogenesis and function in the mitochondria, and the alteration in the fiber type composition may be attributable to the marked IMTG accumulation in the soleus muscle of the rat. Anat Rec, 2011.

BMP2, BMP4, and their receptors are expressed in the differentiating muscle tissues of mouse embryonic tongue

To investigate the role of bone morphogenetic proteins (BMPs) in the differentiation process of skeletal muscle, we analyzed the in vivo expression of BMP2 and BMP4, of BMP receptors (BMPR) IA, IB, and II, and of activin receptors (ActR) IA, II, and IIB in mouse tongue muscle between embryonic day 11 (E11) and E17. The mRNA expression levels for BMP2 were 5-fold to 11-fold greater than those for BMP4 between E13 and E17 (P < 0.05-0.01). Expression of the BMP2, BMPRIB, ActRIA, ActRII, and ActRIIB proteins was first observed at E13. Expression of BMP2 and BMPRIB was detected in the whole area of the differentiating muscle tissues identified by immunostaining for fast myosin heavy chain (fMHC), but that of ActRIA, ActRII, and ActRIIB was detected only in the peripheral area of the differentiating muscle tissues. In the E15 tongue, all of the BMPs, BMPRs, and ActRs studied herein were expressed in the whole area of the differentiating muscle tissues identified by immunostaining for fMHC. These results suggest that BMPs play a role in the differentiation of tongue muscle tissues at E15 but have little or no effect at E13.

BMP-2 Regulates the Formation of Oral Sulcus in Mouse Tongue by Altering the Balance Between TIMP-1 and MMP-13

The aim of this study is to investigate whether BMP‐2 regulates the oral sulcus formation of mouse embryonic tongue by modifying the expression of TIMP and MMP. The BMP‐2 siRNA induced a 180% increase in the depth of oral sulcus cavity (P < 0.01) by stimulating the invagination of oral sulcus into the mesenchymal tissues consisting of tongue floor, whereas the recombinant BMP‐2 suppressed the process in the organ culture system of mouse embryonic tongue. The BMP‐2 siRNA induced a 60% decrease in the expression of TIMP‐1 mRNA (P < 0.05) and a drastic decline in TIMP‐1 protein was observed around the oral sulcus in the BMP‐2 siRNA treated mandibles. The recombinant BMP‐2 induced a 220% increases in the expression of TIMP‐1 mRNA and the area of the immunostaining for TIMP‐1 around the oral sulcus was larger in the mandibles treated with the recombinant BMP‐2 than the vehicle. The BMP‐2 siRNA induced a 60% increase in the expression of MMP‐13 protein and a marked increase in the staining intensity for MMP‐13 was observed in the epithelial region of the BMP‐2 siRNA treated mandibles. The recombinant BMP‐2 induced a 70% decrease in the expression of MMP‐13 mRNA and the decrease was mainly observed in the tissues around oral sulcus. The expressions of BMP‐2, TIMP‐1, and MMP‐13 were verified in the tissues around in vivo developing oral sulcus at E11, 12, and 13 by immunohistochemistry. These results suggest that BMP‐2 regulates the formation of oral sulcus by altering the balance between TIMP‐1 and MMP‐13. Anat Rec 293:1408–1415, 2010.

Factors associated with the presence of atrophic tongue in patients with dry mouth

PURPOSE This study aimed to identify factors associated with atrophic tongue in patients with dry mouth. METHODS Discriminant analysis was performed in 1265 patients with dry mouth to identify factors that might influence the risk of developing atrophic tongue. The dependent variable was the presence of atrophic tongue, while patient age, resting saliva flow rate, stimulated saliva flow rate and Candida colony-forming units (CFU) were used as the independent variables. RESULTS The standardised linear discriminant coefficients showed that Candida CFU, stimulated saliva flow rate and age were significantly associated with the presence of atrophic tongue. The following linear discriminant function was obtained: z = 0.024 × age - 0.63 × (resting saliva flow rate) - 0.81 × (stimulated saliva flow rate) + 0.002 × Candida CFU - 0.611. CONCLUSION High Candida CFU, low stimulated saliva flow rate and advanced age were identified as closely associated factors for the risk of development of atrophic tongue.

TGFbeta3 is expressed in differentiating muscle of the embryonic mouse tongue.

The purpose of the present study was to elucidate the involvement of transforming growth factor betas (TGFbetas) in the differentiation of tongue striated muscles by analyzing the expression of TGFbetas, their receptors and factors of TGFbeta signal transduction in the mouse tongue between embryonic days 11 (E11) and E15. The expression levels of TGFbeta3 mRNA and protein were much higher than those of TGFbeta1 and TGFbeta2, and the immunolocalization of TGFbeta3 was more consistent with the differentiating muscle cells in comparison with those of TGFbeta1 and 2 between E12 and E15. TGFbetaRI and II were localized to the differentiating muscle cells between E11 and E15. Phosphorylated-smad2/3 was localized to the nucleus of muscle cells which just began to differentiate. These results suggest that the signal of TGFbeta3, but not that of beta1 or beta2, may be involved in the early stages (particularly the beginning) of differentiation of mouse tongue muscle cells through TGFbetaRI, TGFbetaRII, and smad2/3.

Development of a new system for measuring the mean film thickness of the white silicone on the fitness test of the denture base

A new system is developed for measuring the mean film thickness of the white silicone on the fitness test of the denture base. This system is based on analysing the B/W film density replaced from the thickness of the silicone. The detective feature of this system is as follows: 1. An adequate correlation between the logarithm of the thickness of the white silicone and the logarithm of the B/W film density was estimated from the results of experimental values. 2. With use of the computer assembled into the system, it is capable to quickly process data. 3. Compared with the conventional method, the proper suggestion was gotten to the clinical data. 4. The system is available to use of investigating the bite force and the mean film thickness of the white silicone.