Effects of conservative treatment of 2-week rigorous bed rest on muscle disuse atrophy in osteoporotic vertebral fracture patients / Journal of Rural Medicine

Objective: Osteoporotic vertebral fracture (OVF) is conventionally treated with conservative management such as bed rest, but a relatively prolonged bed rest has the potential risk of muscle disuse atrophy. This study aimed to examine whether the 2-week of rigorous bed rest affects muscle disuse atrophy in OVF patients.Patients and Methods: A total of 54 OVF patients (16 males; 38 females; mean age, 80.2 ± 9.2 years) were treated with an initial 2-week rigorous bed rest by hospitalization with persistent rehabilitation. Cognitive function, swallowing function, grip strength, and lower extremity circumference were evaluated at three-time points (admission, end of bed rest, and discharge).Results: Of the 51 patients who were able to walk independently before the injury, one patient (2.0%) had to use a wheelchair after the injury. During hospitalization, cognitive function decline was observed in 33.3% of patients, but not in patients with Revised Hasegawa’s Dementia Scale score ≥25 at admission. Swallowing function decline was observed in one patient, and none of the patients developed aspiration pneumonia during hospitalization. The grip strength significantly improved both at the end of bed rest (P=0.04) and discharge (P=0.02). Although the lower extremity circumference significantly decreased at the end of bed rest (P<0.01), it was recovered afterward. The lower extremity circumference did not significantly differ between the admission and discharge (P=0.17).Conclusion: Our results suggested that conservative treatment of OVF through an initial 2-week rigorous bed rest with persistent hospital rehabilitation poses a low risk of muscle disuse atrophy. If cognitive dysfunction is observed on admission, close monitoring for exacerbation should be performed during the hospital stay.

Short-term creatine supplementation changes protein metabolism signaling in hindlimb suspension

The effect of a short-term creatine supplementation on hindlimb suspension (HS)-induced muscle atrophy was investigated. Creatine monohydrate (5 g/kg b.w. per day) or placebo, divided in 2 daily doses, was given by oral gavage for 5 days. Rats were maintained in HS with dietary supplementation concomitantly for 5 days. Body weight, soleus and EDL muscle masses, and cross-sectional areas (CSA) of the muscle fibers were measured. Signaling pathways associated with skeletal muscle mass regulation (FST, MSTN, FAK, IGF-1, MGF, Akt, mTOR, atrogin-1, and MuRF1 expressions, and Akt, S6, GSK3B, and 4EBP1 proteins) were evaluated in the muscles. Soleus muscle exhibited more atrophy than the EDL muscle due to HS. Creatine supplementation attenuated the decrease of wet weight and increased p-4EBP1 protein in the EDL muscle of HS rats. Also, creatine increased mTOR and atrogin-1 expressions in the same muscle and condition. In the absence of HS, creatine supplementation increased FAK and decreased MGF expressions in the EDL muscle. Creatine attenuated the increase in FST expression due to HS in the soleus muscle. MuRF1 expression increased in the soleus muscle due to creatine supplementation in HS animals whereas atrogin-1 expression increased still further in this group compared with untreated HS rats. In conclusion, short-term creatine supplementation changed protein metabolism signaling in soleus and EDL muscles. However, creatine supplementation only slightly attenuated the mass loss of both muscles and did not prevent the CSA reduction and muscle strength decrease induced by HS for 5 days.

Sarcomere structure: the importance of desmin protein in muscle atrophy / Estructura de sarcómera: la importancia de proteína desmina en atrofia muscular

Knowing the ultrastructure of skeletal muscle is critical to understand how it works under normal situation and the disorders caused by extreme or pathological conditions. Sarcomere is the basic structural unit of striated muscle tissue. An important element of sarcomere architecture are the intermediate filaments, including the desmin protein. Desmin protein contributes to maintenance of cell integrity, efficient transmission of force and mechanochemical signaling within the myocyte. Because of this, desmin protein has constantly been a focus of research that investigates its alterations associated to damage and muscle atrophy under different conditions. The purpose of the following literature review is to describe the basic concepts of muscle ultrastructure, emphasizing the desmin protein role under conditions of muscle disuse atrophy and aging.

Conocer la ultraestructura del músculo esquelético es crítico para entender cómo trabaja bajo situaciones normales y en desórdenes causados por condiciones extremas o patológicas. La sarcómera es la unidad de estructura básica del tejido muscular estriado. Elementos importantes en la arquitectura de la sarcómera son los filamentos intermedios, incluyendo la proteína desmina. La proteína desmina contribuye en mantener la integridad celular, la transmisión eficiente de fuerza y la señalización mecanoquímica dentro del miocito. Debido a lo anterior, la proteína desmina ha sido constante foco de investigación en trabajos que estudian sus alteraciones asociadas a daño y atrofia muscular bajo diferentes condiciones. El propósito de la siguiente revisión de la literatura es describir los conceptos básicos de la ultraestructura muscular, enfatizando en el rol de la proteína desmina bajo condiciones de atrofia muscular por desuso y envejecimiento.

Balloon dilation of jejunal afferent loop functional stenosis following left hepatectomy and hepaticojejunostomy long time after pylorus-preserving pancreaticoduodenectomy: a case report

We present a rare case of functional stenosis of the jejunal loop following left hepatectomy and hepaticojejunostomy long after pylorus-preserving pancreaticoduodenectomy (PPPD), which was successfully managed by balloon dilation. A 70-year-old Korean man had undergone PPPD 6 years before due to 1.8 cm-sized distal bile duct cancer. Sudden onset of obstructive jaundice led to diagnosis of recurrent bile duct cancer mimicking perihilar cholangiocarcinoma of type IIIb. After left portal vein embolization, the patient underwent resection of the left liver and caudate lobe and remnant extrahepatic bile duct. The pre-existing jejunal loop and choledochojejunostomy site were used again for new hepaticojejunostomy. The patient recovered uneventfully, but clamping of the percutaneous transhepatic biliary drainage (PTBD) tube resulted in cholangitis. Biliary imaging studies revealed that biliary passage into the afferent jejunal limb was significantly impaired. We performed balloon dilation of the afferent jejunal loop by using a 20 mm-wide balloon. Follow-up hepatobiliary scintigraphy showed gradual improvement in biliary excretion and the PTBD tube was removed at 1 month after balloon dilation. This very unusual condition was regarded as disuse atrophy of the jejunal loop, which was successfully managed by balloon dilation and intraluminal keeping of a large-bore PTBD tube for 1 month.

The effects of fracture fixation on joint contracture and disuse atrophy in immobilized rat soleus muscle / 体力科学

In the present study, we investigated the effects of fracture fixation on joint contracture and disuse muscle atrophy. We surgically fractured the right hind limbs of male Wistar rats, and then fixed the right ankle joints at maximal plantar flexion for two weeks using dorsal splints. Compared with immobilized healthy and sham operated joints, the fractured joints concomitantly showed highly restricted range of motion and significantly higher degrees of disuse atrophy in soleus muscle; decrease of muscle fiber cross sectional area, development of central core lesion and a change in myosin heavy chain isoforms from slow type myosin to fast type myosin. Therefore, it is suggested that orthopedic fracture fixation induces intense disuse muscle atrophy to aggravate joint contracture.

Metformina minimiza as alterações morfométricas no músculo sóleo de ratos submetidos à imobilização articular / Metformin minimizes the morphometric alterations in the soleus muscle of rats submitted to articular immobilization

A proposta deste trabalho foi avaliar o músculo sóleo (S) de ratos submetidos à imobilização articular por sete dias, associado ou não ao tratamento com metformina (MET, 1,4mg.ml-1) por meio de análises morfométricas. Ratos adultos Wistar (n = 5) foram divididos nos grupos: controle (C), imobilizado em posição neutra do tornozelo (I), tratado com metformina (M), imobilizado tratado com metformina (I + MET). Foram avaliadas a área das fibras, a densidade de área do tecido conjuntivo intramuscular e a massa muscular do S. A análise estatística foi realizada pelo teste de normalidade, ANOVA e de Tukey (p < 0,05). A imobilização reduziu o peso muscular (mg) do S (34 por cento). No grupo M não houve alteração significativa do peso muscular quando comparado com o grupo C. Já no grupo I + MET foi observado aumento do peso muscular em 29,6 por cento quando comparado com o grupo I. O tratamento com metformina não alterou a área da fibra muscular quando comparado com grupo C. Já no grupo I, houve redução de 44 por cento na área da fibra. Com relação ao grupo I + MET, houve aumento de 22 por cento quando comparado com o grupo I. Por outro lado, ao compararmos o grupo C com o grupo I + MET, houve redução de 31 por cento. Ao avaliar a densidade de área do tecido conjuntivo, observou-se que o grupo I apresentou elevação de 216 por cento quando comparado com o grupo C. No grupo I + MET, houve redução de 67 por cento comparado com o grupo I. O tratamento com metformina em músculos submetidos à imobilização minimizou a redução da área das fibras do S, bem como o aumento do tecido conjuntivo. Esses resultados sugerem que a metformina pode favorecer recuperação mais rápida na fase pós-imobilização.

The aim of this study was to evaluate the effect of metformin treatment on the muscle mass, fibers area and connective tissue area density in soleus (S) muscle under articular immobilization. METHODS AND RESULTS: Male Wistar rats (250-300g) were divided in 4 groups (n=5): control, treated with metformin, immobilized and immobilized treated with metformin. Immobilization was performed by acrylic resin orthoses on the left hindlimb keeping the ankle in neutral position during 7 days. The animals were euthanatized and the S muscle was dissected and weighed. Samples of its ventral portion were treated for inclusion in paraffin and stained in Hematoxylin-Eosin (H:E). The results were obtained through analyses of the muscular fiber area (images analyzed - Image Pró-plus 4,0), as well as of intramuscular connective tissue by means of planimetry. The statistical analysis was performed by normality test followed by ANOVA and Tukey (p<0.05). Hindlimb immobilization during 7 days promoted significant reduction (p<0.05) of 35 percent in the muscular mass; 44 percent (p<0.05) in the fiber area and increase of 216 percent (p<0.05) in the intramuscular connective tissue. The metformin in immobilized group promoted significant alterations (p<0.05) in the muscular mass. In addiction, it was observed significant increase (p<0.05) of 29.6 percent in the fibers area and significant reduction (p<0.05) of 67 percent in the intramuscular connective tissue. CONCLUSION: The metformin treatment minimized the reduction of muscle fibers area, as well as the increase of connective tissue in hindlimb immobilized muscle. These results suggest that metformin should be used to increase fast muscle recovery after hindlimb immobilization.

Sufficient quantity of leg exercise for prevention of disuse atrophy of the quadriceps femoris murcle / 体力科学

A study was conducted to determine the minimum quantity of leg exercise required to prevent disuse atrophy of the quadriceps femoris muscle during bed rest. The subjects were 10 normal young university students with a mean age of 21.1 years. First, analysis of rectified filtered electromyography (RFEMG) was performed on the rectus femoris and vastus medialis during walking with cadences of 100 steps/min and 150 steps/min. Then, the effects of straight leg raising (SLR), patella setting (PS), knee extension-flexion in a supine position (KEF) and knee extension in a sitting position (KE) were analysed for each muscle using the same method. Based on the value of RFEMG for each muscle during walking, the repetition number for each exercise was calculated. For the rectus femoris, the repetition number for each exercise corresponding to 10000 steps with a cadence of 100 steps/min was 289 for SLR, 466 for PS, 1255 for LEF and 1663 for KE. For the vastus medialis, the corresponding numbers were 1223, 381, 6367 and 2170, respectively. When the cadence increased to 150 steps/min, the repetition number of each exercise for each muscle also increased. These results indicate that high repetition exercise is recommendable to prevent disuse atrophy of the quadriceps femoris muscle. Therefore, the activity of patients should be increased to stimulate weakened muscles such as the quadriceps femoris during hospitalization.

Experimental Studies on Disuse Atrophy of the Rat Tibialis Anterior Muscle / 대한정형외과학회잡지

The experiment was designed to investigate type-selectivity of the involved muscle fibers and changes in the component ratios of the fiber types following the progression of disuse atrophy in the skeletal muscle. After inducing disuse atrophy of the skeletal muscle by applying cast on the hind limb, we used histological and histochemical stains in the sections of the rat Tibialia anterior muscles. The results were as follows. 1. Even 8 weeks after immobilization of the hind limb, differentiation of muscle fiber types by histolo gical and histochemical staining methods in the Tibialis anterior muscle could be possible. 2. Atrophy of muscle fibers was more pronounced in type IIB and type I fibers than in type IIA fibers. 3. Central migration of sarcolemmal nuclei and ring fiber appeared after 6th and 8th weeks of immobilization respectively, in the H&E and trichrome preparations. Ac-pase or Alk-pase positive fibem were not noted throughout the experimental periods.