Homoplasmic mitochondrial tRNAPro mutation causing exercise-induced muscle swelling and fatigue

A new family with a case of severe early-onset muscle fatigue and a peculiar maternally inherited painful swelling in chewing muscles associated with homoplasmic m.15992A>T mutation in mitochondrial tRNAPro

A 16-year-old boy was evaluated for a history of exercise-induced fatigability associated with nausea even after minimal effort, lower limbs muscle hypotrophy, and swelling of the masseter muscles after chewing. Laboratory tests were remarkable for hyperlactatemia and metabolic acidosis after short physical activity. The muscle biopsy showed non-specific mitochondrial alterations and an increase in intrafibral lipids. Biochemical analysis showed reduced activity of the respiratory chain complexes. Mitochondrial DNA sequencing revealed the presence of a homoplasmic variant m.15992A>T in the MT-TP gene, coding for the mt-tRNAPro in the patient, in his mother and in his brother. Pathogenic or likely pathogenic variants in MT-TP gene are rare. They are responsible for different clinical presentation, almost ever involving the muscle tissue. We report the first family with exercise-induced muscle weakness and swelling of the chewing muscles due to m.15992A>T variant in absence of J1c10 haplogroup, confirming its pathogenicity.

CHINESE MEDICINAL BATH ON ATHLETES’ SPORT MUSCLE FATIGUE

ABSTRACT Introduction: The Fifth International Conference on Sports Biochemistry defines sports fatigue as the physiological process of dysfunction at a certain level or inability to maintain predetermined exercise intensity. When left untreated, it can cause adverse effects to the musculoskeletal system. Natural alternatives for controlling sports fatigue exist in Chinese culture, but scientific research is needed to determine the effectiveness of these treatments. Objective: This study aimed to verify the effect of traditional Chinese medicinal baths on athletes’ muscle fatigue. Methods: 100 athletes with exercise-induced muscle fatigue were randomly divided into two groups. The control group received ganglioside injection combined with therapeutic exercise protocols, while the experimental group received the medicinal bath based on traditional Chinese medicine. Tonus of adductors, ischiotibials, gastrocnemius, in addition to lower limb motor function, was evaluated. Results: The total effective rate (90.8%) of the observation group was higher than that of the control group (72.3%), and the difference was statistically significant (P<0.05). After treatment, adductor, hamstring, and gastrocnemius muscle tension in the observation group were lower than the control group (P<0.05). Gross motor function assessment score (GMFM-88), Berg Balance Scale (BBS), 10m walking speed on a 20cm wide walkway (MWS) in the observation group were higher than those in the control group (P<0.05). Conclusion: Chinese herbal lavender lotion combined with suspension exercise can effectively improve the body's muscle strength after exercises, accelerate the recovery of muscle strength, and significantly reduce exercise-induced muscle fatigue. Evidence Level II; Therapeutic Studies - Investigating the result.

Roles of tRNA metabolism in aging and lifespan

Transfer RNAs (tRNAs) mainly function as adapter molecules that decode messenger RNAs (mRNAs) during protein translation by delivering amino acids to the ribosome. Traditionally, tRNAs are considered as housekeepers without additional functions. Nevertheless, it has become apparent from biological research that tRNAs are involved in various physiological and pathological processes. Aging is a form of gradual decline in physiological function that ultimately leads to increased vulnerability to multiple chronic diseases and death. Interestingly, tRNA metabolism is closely associated with aging and lifespan. In this review, we summarize the emerging roles of tRNA-associated metabolism, such as tRNA transcription, tRNA molecules, tRNA modifications, tRNA aminoacylation, and tRNA derivatives, in aging and lifespan, aiming to provide new ideas for developing therapeutics and ultimately extending lifespan in humans.