Ageing, Muscle Power and Physical Function: A Systematic Review and Implications for Pragmatic Training Interventions.

BACKGROUND: The physiological impairments most strongly associated with functional performance in older people are logically the most efficient therapeutic targets for exercise training interventions aimed at improving function and maintaining independence in later life. OBJECTIVES: The objectives of this review were to (1) systematically review the relationship between muscle power and functional performance in older people; (2) systematically review the effect of power training (PT) interventions on functional performance in older people; and (3) identify components of successful PT interventions relevant to pragmatic trials by scoping the literature. METHODS: Our approach involved three stages. First, we systematically reviewed evidence on the relationship between muscle power, muscle strength and functional performance and, second, we systematically reviewed PT intervention studies that included both muscle power and at least one index of functional performance as outcome measures. Finally, taking a strong pragmatic perspective, we conducted a scoping review of the PT evidence to identify the successful components of training interventions needed to provide a minimally effective training dose to improve physical function. RESULTS: Evidence from 44 studies revealed a positive association between muscle power and indices of physical function, and that muscle power is a marginally superior predictor of functional performance than muscle strength. Nine studies revealed maximal angular velocity of movement, an important component of muscle power, to be positively associated with functional performance and a better predictor of functional performance than muscle strength. We identified 31 PT studies, characterised by small sample sizes and incomplete reporting of interventions, resulting in less than one-in-five studies judged as having a low risk of bias. Thirteen studies compared traditional resistance training with PT, with ten studies reporting the superiority of PT for either muscle power or functional performance. Further studies demonstrated the efficacy of various methods of resistance and functional task PT on muscle power and functional performance, including low-load PT and low-volume interventions. CONCLUSIONS: Maximal intended movement velocity, low training load, simple training methods, low-volume training and low-frequency training were revealed as components offering potential for the development of a pragmatic intervention. Additionally, the research area is dominated by short-term interventions producing short-term gains with little consideration of the long-term maintenance of functional performance. We believe the area would benefit from larger and higher-quality studies and consideration of optimal long-term strategies to develop and maintain muscle power and physical function over years rather than weeks

Neonatal hyperthyroidism: neonatal clinical course of two brothers born to a mother with Graves-Basedow disease, before and after total thyreoidectomy

BACKGROUND: About 1-2% of infants born to mothers with Graves' disease or Hashimoto's thyroiditis develop neonatal hyperthyroidism because of transplacental passage of IgG stimulating TSH receptors (TRAb). OBJECTIVE: To evaluate the effect of maternal total thyroidectomy on neonatal clinical course. METHODS: We describe two brothers born to a mother with Graves' disease, before and after total thyroidectomy. RESULTS: The first child showed persistent tachycardia, the presence of TRAb and a laboratory pattern of hyperthyroidism. Lugol's solution was started and then propylthiouracil was added. Digitalis, furosemide and diazepam were necessary for treatment of heart failure, hypertension and irritability. On the 70th day of life, hormone serum levels normalized and treatment was interrupted. TRAb normalized by the third month of life. The second infant was born 2 years after the mother underwent total thyroidectomy. In spite of a laboratory pattern of hyperthyroidism and positivity to TRAb, he showed only considerable weight loss, and no therapy was required. CONCLUSIONS: TRAb may persist after total thyroidectomy: clinical and instrumental follow-up of the newborn is recommended

The C2B Ca2+-binding motif of synaptotagmin is required for synaptic transmission in vivo

Synaptotagmin is a synaptic vesicle protein that is postulated to be the Ca2+ sensor for fast, evoked neurotransmitter release. Deleting the gene for synaptotagmin (sytnull) strongly suppresses synaptic transmission in every species examined, showing that synaptotagmin is central in the synaptic vesicle cycle. The cytoplasmic region of synaptotagmin contains two C2 domains, C2A and C2B. Five, highly conserved, acidic residues in both the C2A and C2B domains of synaptotagmin coordinate the binding of Ca2+ ions, and biochemical studies have characterized several in vitro Ca2+-dependent interactions between synaptotagmin and other nerve terminal molecules. But there has been no direct evidence that any of the Ca2+-binding sites within synaptotagmin are required in vivo. Here we show that mutating two of the Ca2+-binding aspartate residues in the C2B domain (D416, 418N in Drosophila) decreased evoked transmitter release by >95%, and decreased the apparent Ca2+ affinity of evoked transmitter release. These studies show that the Ca2+-binding motif of the C2B domain of synaptotagmin is essential for synaptic transmission