The influence of myosin regulatory light chain phosphorylation on the contractile performance of fatigued mammalian skeletal muscle

ABSTRACT The myosm regulatory light chain (RLC) of type II fibres is phosphorylated by Ca2+ -calmodulin dependent myosin light chain kinase (skMLCK) during muscular activation. The purpose of this study was to explore the effect of skMLCK gene ablation on the fatigability of mouse skeletal muscles during repetitive stimulation. The absence of myosin RLC phosphorylation in skMLCK knockout muscles attenuated contractile performance without a significant metabolic cost. Twitch force was potentiated to a greater extent in wildtype muscles until peak force had diminished to ~60% of baseline (37.2 ± 0.05% vs. 14.3 ± 0.02%). Despite no difference in peak force (Po) and shortening velocity (Vo), rate of force development (+dP/dt) and shortening-induced deactivation (SID) were almost two-fold greater in WT muscles. The present results demonstrate that myosin RLC phosphorylation may improve contractile performance during fatigue; providing a contractile advantage to working muscles and protecting against progressive fatigue.

The light and dark sides of perfectionism : implications for health and well-being

The present work presents two studies that examined the association of perfectionism, operationally defined by Hewi t t and Fl e t t ' s (1991) multidimensional mode l of perfectionism, with health and subjective well-being (SWB). The underlying question of this research was whether perfectionism could be beneficial as well as detrimental to health and well-being, as this is one of the mos t highly debated questions in the current literature. In samples of relatively healthy university students (n = 538) and community adults suffering from various chronic illnesses (n = 772), results from Study One indicated that socially prescribed perfectionism (SPP) is directly associated wi th poor e r he a l th and well-being. Results further showed f rom a personcentered perspective that there is a l a rge group of individuals wi th high levels of SPP and that i t is indeed these individuals who reported the poorest health and lowe s t levels of well-being. Other-oriented perfectionism was found to be unrelated to health and SWB. Findings revealed that when perfectionism is self-imposed (i.e., self-oriented perfectionism; SOP), i t is neither healthy nor unhealthy in an absolute sense. From the variable-centered perspective, this conclusion was supported by the f a c t tha t SOP was associated wi th both positive (e.g., be t t e r mental health and highe r levels of SWB in the student sample), and nega t ive correlates (e.g., higher levels of negative affect, stress, and neuroticism in both samples). Evidence f rom the chronically-ill sample further substantiated this conclusion by showing that there may be an optimal level of SOP, because mode r a t e levels of SOP we r e found to be associated with be t t e r health and highe r levels of SWB, whereas levels tha t we r e too low or too high we r e found to be associated with poor e r health and lowe r levels of SWB. Findings f rom the person-centered approach we r e particularly informative, in that they not only demonstrated tha t unique profiles of

Reflected rays of light upon Freemasonry, or, the Freemason's pocket compendium (1874)

"With an emblematical frontespiece." Inscribed on front free endpaper: A. Graham Barrie 30th Sep 1881.

Myosin Regulatory Light Chain Phosphorylation and Its Effect on the Contractile Economy of Mouse Fast Muscle

Activated by elevations in myoplasmic calcium concentration, myosin light chain kinase (skMLCK) phosphorylates the regulatory light chains (RLCs) of fast muscle myosin. This covalent modification potentiates force production, but requires an investment of ATP. Our objective was to investigate the effect of RLC phosphorylation on the contractile economy (mechanical output:metabolic input) of fast twitch skeletal muscle. Extensor digitorum longus muscles isolated from Wildtype and skMLCK-/- mice mounted in vitro (25°C) were subjected to repetitive low-frequency stimulation (10Hz,15s) known to cause activation of skMLCK, and staircase potentiation of force. With a 3-fold increase in RLC phosphate content, Wildtype generated 44% more force than skMLCK-/- muscles over the stimulation period (P = .002), without an accompanied increase in energy cost (P = .449). Overall, the contractile economy of Wildtype muscles, with an intact RLC phosphorylation mechanism, was 73% greater than skMLCK /- muscles (P = .043), demonstrating an important physiological function of skMLCK during repetitive contractile activity.

Receipt from the St. Catharines and Welland Canal Gas Light Company

Receipt from the St. Catharines and Welland Canal Gas Light Company for gas rent, April 4, 1887.

Receipt from St. Catharines and Welland Canal Gas Light Company

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent, May 1, 1887.

Receipt from St. Catharines and Welland Canal Gas Light Company

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent, June 6, 1887.

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent, July 4, 1887.

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent, Sept. 3, 1887.

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent

Receipt from St. Catharines and Welland Canal Gas Light Company for gas rent, Dec. 31, 1887.

Evaluación cuantitativa de la oxidación-reducción en un vidrio calizo cristalino y su efecto sobre el color por Tomás Hernández Niño

Tesis (Maestría en Ciencias con Especialidad en Ingeniería Cerámica) U.A.N.L.

Evaluación de dos diferentes técnicas de instrumentación Light Speed y Profile en conductos moderadamente curvos (Un estudio comparativo)

Tesis ( Maestría en Ciencias Odontológicas con Especialidad en Endodoncia) U.A.N.L.

Color studies and a mexican campaign

UANL