Effects of coenzyme Qi0 on bone microstructure and myofibril structure induced by D-galactose in male mice / 中国药理学通报

; Aim To observe the effects of CoQ10 on bone microstructure and myofibril structure induced by D-galactose in male mice. Methods Forty male mice were randomly divided into control group, model group, calcitriol group and CoQ10 group, in which drugs were given for 12 weeks. At the end of the experiment, the mice were sacrificed and the femurs were taken for micro-CT and biomechanics analysis. The gastrocnemius muscle was taken for transmission electron microscope examination. Results Compared with control group, the maximum load and stiffness of femur in model group significantly decreased (P < 0. 01). The micro-CT parameters showed that Conn. D and BMD markedly decreased (P < 0. 05), while Tb. Sp evidently increased (P <0. 05). In model group, the gastrocnemius muscle fibrils parameters showed that the length of sarcomere, I-band, H-zone, M-line and Z-line significantly increased (P < 0. 01), while the length of overlapped actin and myosin filaments significantly decreased (P < 0. 01) . Compared with model group, the maximum load, Conn. D., BMD and Tb. Th of femur in coenzyme Q 1 0 group markedly increased (P < 0. 05), while SMI and Tb. Sp significantly decreased (P < 0 . 01) . Moreover, I-band, H-zone, M-line and Z-line were significantly shortened (P < 0 . 01) . Conclusion Coenzyme Q10 can improve bone microstructure damage and the contractility of gastrocnemius muscle in male mice induced by D-galactose.

Relationship between Myofibril Fragmentation Index and Postmortem Interval / 法医学杂志

Objective To study the relationship between myofibril fragmentation index (MFI) of human skeletal muscle and postmortem interval (PMI). Methods The protein concentrations of human right bi-ceps brachii muscle and right quadriceps femoris muscle were obtained at different PMI, and detected at room temperature by biuret method. The MFI of skeletal muscle at 540 nm was measured by ultraviolet spectrophotometer. Regression analysis was performed with time of death as independent variable (x) and MFI as dependent variable (y). Results In early PMI, the MFI of human skeletal muscle increased obviously according to the prolongation of PMI, and peaking by 12 h and then tended to steady. Within 12 h after death, the regression equations of right biceps brachii muscle and right quadriceps femoris muscle were y=32.660+3.227 x(r=0.9879) and y=32.380+3.495 x(r=0.9839), respectively. Conclusion There's high correlation between MFI and PMI. Combining with forensic practice, MFI can be used for the estimation of early PMI (especially in 12 h).

Characteristics and mechanisms of low-frequency muscle fatigue: alterations in skeletal muscle / 体力科学

Repeated contractions of skeletal muscle cause fatigue, as manifested by a reduced ability to produce force and slowed contraction. During studies of muscle fatigue, a phenomenon known as low-frequency fatigue (LFF) was observed in human skeletal muscles. It is characterized by a greater loss of force in response to low- versus high-frequency muscle stimulation and a long period of time for full recovery. This force deficit is most likely to be owing to disturbances in sarcoplasmic reticulum (SR) Ca²⁺ release and/or reductions in myofibrillar Ca²⁺ sensitivity. Studies on metabolites have implied that inorganic phosphate and Mg²⁺ might have some role in reduced SR Ca²⁺ release that occurs immediately after fatiguing contraction. In addition, recent experiments have shown that impaired myofibril function may relate to increased nitric oxide and hydroxyl radical production, whereas deterioration of SR function may be attributable to increased superoxide production, elevation of cytoplasmic Ca²⁺ concentration and/or decreased muscle glycogen. Finally, we will discuss possible proteins which are affected and contribute to the development of LFF.

Chemical basis for beef charqui meat texture

This work evaluated the relationship of charqui meat (CHM) chemical composition with the tenderness throughout its production. CHM was prepared from beef Vastus lateralis of 4-5 years old. Shear force of fresh CHM showed an approx. 3-fold increase in toughness compared to the raw material while, in the case of cooked CHM it was 6-fold increased in relation to the raw charqui. The moisture content decreased by 39.0 and 58.0 percent (p<0.05) for uncooked and cooked CHM, respectively, in relation to the raw material. Mathematical modeling of the influence of these meat components showed that shear force increased exponentially with the loss of moisture. The texture of CHM was the result of a multitude of factors involving myofibril proteins which promoted dynamic biochemical events such as the binding of water molecules. It was the amount of the latter which ultimately determine the final charqui meat texture.

Este trabalho avaliou a relação entre a composição química aproximada do charque (CHM) com a maciez durante todas as etapas de sua produção. CHM foi produzida do m. Vastus lateralis bovino (patinho) de aproximadamente 4-5 anos de idade. A força de cisalhamento do charque cru mostrou o valor aproximado de 3 vezes maior em dureza comparada à matéria prima enquanto que no caso do CHM cozido houve 6 vezes maior em aumento sob as mesmas condições.O índice de umidade diminui de 39 a 58 por cento (p<0,05) para CHM cru e cozido, respectivamente, em relação à matéria prima. O modelo matemático da influência destes componentes mostrou que a força de cisalhamento aumentou exponencialmente com a perda de umidade. A textura do charque é o resultado da associação de multifatores envolvendo proteínas miofibrilares que provocam eventos bioquímicos dinâmicos como a sua ligação com as moléculas da água. É a quantidade destas que determina a textura final do charque.

THE RESPONSE TO CYTOCHALASIN D SEEN IN PRIMARY CULTURED CARDIOCYTES FROM ADULT HUMAN AND ADULT RAT / 解剖学报

10?m cytochalasin D (CD) was used to treat cardiocytes from adult human atrium and adult rat atrium and ventricle in long-term primary cultures. Durations of treatment were 0.5, 1, 6, 12, 24 and 48h. In some cultures, the medium containing CD was removed at the planned time to be replaced with the medium without CD.These dishes were then cultured for an additional 48h. Control cultures were exposed to dimethyl sulfoxide (DMSO), the vehicle used to dissolve CD. All cultured cells were first stained with rhodamine-labelled phalloidin to show F-actin and then stained with fluoreseein-labelled antitubulin to show microtubles. The freshly isolated and rounded cardiocytes did not respond to CD, while the spreading cells responded apparently. The actin filament bundles in the peripheral zone of spreading cells were cut into segments. Most segments were gathered into aggregates and granules. Some aggregates were lodged on the inner aspect of the sarcolemma. Small vacuoles were seen between the myofibrils or somewhere along the course of the myofibrils. The CD response from the atrial spreading cells, especially the human atrial spreading cells, were more obvious than that from the rat ventricular cells. Cells exposed to CD and then cultured in normal medium for 48h did not return to normal. Microtubules were not directly affected by CD, but in places where vacuolization occured they made way for vacuoles. All the control cultures made no response to DMSO. The above-mentioned results suggest that different sensitivity to CD existed in cultured adult cardiocytes between different species and that a difference also existed in the contractile machinery between the atrial culturing cells and ventricular cultureing cells of the same species.