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.

The results of the present study suggest that the need for oral hygiene management by dental professionals increases as dementia advances. However, current systems that provide regional dental care are structured based on the level of care need and the degree of independence. A dementia perspective needs to be added to these systems. Geriatr Gerontol Int 2016; 16: 956-962.

Oral ingestion influences the life sustenance, quality of life, and dignity of older adults. Thus, it is an important issue in medical care and the welfare of older adults. The purpose of this four-year prospective cohort study was to investigate the relationship between mortality and oral function among older adults who required long-term care and were living in different settings in a rural area of Japan. This study included 289 participants aged 65 and older who required long-term care and lived in the former Omorimachi area in Yokote City, Akita Prefecture, located in northern Japan. Following the baseline survey, mortality data were collected over four years; 102 participants (35.3%) died during that time. A significant difference was noted in the overall survival rates between the groups with good and deterioration of oral function such as oral dryness, rinsing ability, swallowing function, and articulation, based on Log-rank test results. After adjusting for various potential confounders using Cox proportional-hazards regression, oral dryness (HR: 1.83, 95% confidence interval: 1.12−3.00) was significantly associated with mortality within four years. This study revealed that oral dryness influences the life prognosis of older adults who receive long-term care in different settings.

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 ¼ 20:57:23; 508 kcal/100 g) or a control diet (protein:fat:carbohydrate ¼ 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 realtime 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, 294:1904Rec, 294: -1912Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

No abstract