Role of β-glucans in reducing oxidative stress and improving muscle tissue health in European whitefish (Coregonus lavaretus L.)

MicroRNAs (miRNAs) are an abundant class of small regulatory RNAs that negatively regulate gene expression at the post-transcriptional level. Although an increasing number of porcine miRNAs recently have been identified, research has yet to identify the full repertoire of miRNAs in pig skeletal and adipose tissues and their differences between breeds. We extracted small RNA from skeletal muscle and adipose tissues of Landrace and Lantang pigs, and the expression of a total of 184 known porcine miRNAs (113 from Solexa sequencing and 171 from miRNA chip hybridization) as well as 521 novel miRNA candidates was detected. Moreover, 20 miRNAs were selected randomly from the 184 miRNAs and analysed by quantitative real-time PCR to confirm the aforementioned results. In the skeletal muscle tissues, 21 miRNAs were up-regulated in Lantang and another 33 were highly expressed in Landrace pigs. In the adipose tissues, 25 miRNAs were down-regulated in Lantang and another 23 were lowly expressed in Landrace pigs. miRNA divergence between tissues was also detected in this study. Ten miRNAs were highly expressed in the skeletal muscle tissue in comparison with adipose tissue, and another 10 miRNAs exhibited the opposite expression profile. To investigate the regulatory mechanism of the miRNAs in muscle and adipose tissues, the 10 miRNAs with the most divergent expression profiles were functionally categorized using the Kyoto Encyclopedia of Genes and Genomes database. Most of the miRNAs strongly corresponded to myogenesis and adipogenesis processes. In addition, 84 of the 521 miRNA candidates were potentially porcine-specific miRNAs. This study adds new valuable information to comparative miRNA profiles of skeletal muscle and adipose tissues in porcine species. The great diversity of miRNA composition and expression levels both between breeds and between tissues suggests that a complex regulatory network exists in porcine subcutaneous fat development.

The effect of Fructus Mume formula and its separated prescription extract on insulin resistance in type 2 diabetic rats was investigated. The rat model of type 2 diabetes was established by feeding on a high-fat diet for 8 weeks and by subsequently intravenous injection of small doses of streptozotocin. Rats in treatment groups, including the Fructus Mume formula treatment group (FM), the cold property herbs of Fructus Mume formula treatment group (CFM), the warm property herbs of Fructus Mume formula treatment group (WFM), were administrated with Fructus Mume formula and its separated prescription extract by gavage, while the rats in diabetic model group (DM) and metformin group (MET) were given by gavage with normal saline and metformin correspondingly. The body weight before and after treatment was measured, and the oral glucose tolerance test (OGTT) and the insulin release test (IRT) were performed. The homeostasis model assessment-insulin resistance index (HOMA-IR) was calculated. The protein and mRNA expression levels of Insr, β-arrestin-2, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were detected by using Western blotting and RT-PCR respectively. The results demonstrated that, as compared with DM group, OGTT, IRT (0 h, 1 h) levels and HOMR-IR in treatment groups were all reduced, meanwhile their protein and mRNA expression levels of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were obviously increased, and their protein and mRNA expression levels of β-arrestin-2 in the liver and skeletal muscle tissues were also markedly increased. It was suggested that the Fructus Mume formula and its separated prescription extracts could effectively improve insulin resistance in type 2 diabetic rats, which might be related to the up-regulated expression of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues, and β-arrestin-2 in the liver and skeletal muscle tissues.

Skeletal muscle comprises a family of diverse tissues with highly specialized functions. Many acquired diseases, including HIV and COPD, affect specific muscles while sparing others. Even monogenic muscular dystrophies selectively affect certain muscle groups. These observations suggest that factors intrinsic to muscle tissues influence their resistance to disease. Nevertheless, most studies have not addressed transcriptional diversity among skeletal muscles. Here we use RNAseq to profile mRNA expression in skeletal, smooth, and cardiac muscle tissues from mice and rats. Our data set, MuscleDB, reveals extensive transcriptional diversity, with greater than 50% of transcripts differentially expressed among skeletal muscle tissues. We detect mRNA expression of hundreds of putative myokines that may underlie the endocrine functions of skeletal muscle. We identify candidate genes that may drive tissue specialization, including Smarca4, Vegfa, and Myostatin. By demonstrating the intrinsic diversity of skeletal muscles, these data provide a resource for studying the mechanisms of tissue specialization.

Skeletal muscle comprises a family of diverse tissues with highly specialized functions. Many acquired diseases, including HIV and COPD, affect specific muscles while sparing others. Even monogenic muscular dystrophies selectively affect certain muscle groups. These observations suggest that factors intrinsic to muscle tissues influence their resistance to disease. Nevertheless, most studies have not addressed transcriptional diversity among skeletal muscles. Here we use RNAseq to profile mRNA expression in skeletal, smooth, and cardiac muscle tissues from mice and rats. Our data set, MuscleDB, reveals extensive transcriptional diversity, with greater than 50% of transcripts differentially expressed among skeletal muscle tissues. We detect mRNA expression of hundreds of putative myokines that may underlie the endocrine functions of skeletal muscle. We identify candidate genes that may drive tissue specialization, including Smarca4, Vegfa, and Myostatin. By demonstrating the intrinsic diversity of skeletal muscles, these data provide a resource for studying the mechanisms of tissue specialization.

Altered immunometabolism in adipose tissue: A major contributor to the ageing process?

가물치(Channa argus) 조직의 젖산탈수소효소 동위효소(EC 1.1.1.27, lactate dehydrogenase, LDH)를 정제하고 생화학적, 면역학적 및 역학적 방법으로 특성을 연구하였다. LDH 활성은 골격근이 380.4 units로 가장 높고 심장 13.4, 눈 3.5, 뇌 조직 5.4 units이었으며, 심장의 CS 활성은 20.7 unit로 가장 높고, LDH/CS는 골격근 172.9, 심장 0.6, 눈 0.32, 뇌 0.47이고, 단백질 양은 골격근 14.7 mg/g이며, 특이활성(units/mg)은 골격근 25.88, 심장 0.79, 눈 0.31, 뇌 1.38 units/mg이었으므로 골격근은 혐기적이고, 심장은 호기적이었다. LDH <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX>, eye-specific <TEX>$C_4$</TEX>에 대한 항혈청을 사용한 Western blot, 면역침강반응 및 native-polyacrylamide gel electrophoresis에 의해 <TEX>$A_4$</TEX>, <TEX>$A_3B$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$AB_3$</TEX> 및 <TEX>$B_4$</TEX>가 모든 조직에서 확인되었고, 눈 조직에서 <TEX>$C_4$</TEX>와 <TEX>$AC_3$</TEX>, <TEX>$A_2C_2$</TEX>, <TEX>$AC_3$</TEX>, 뇌 조직에서 <TEX>$A_3C$</TEX>도 확인되었다. LDH <TEX>$A_4$</TEX>, <TEX>$A_3B$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$AB_3$</TEX>, <TEX>$B_4$</TEX>, eye-specific <TEX>$C_4$</TEX> 동위효소는 affinity chromatography와 Preparative PAGE Cell에 의해 정제되었다. LDH <TEX>$A_4$</TEX> 동위효소는 <TEX>$NAD^+$</TEX> 유입 후 정제되었고, eye-specific <TEX>$C_4$</TEX>는 <TEX>$A_4$</TEX>에 이어 용출되기 시작하였으며 <TEX>$B_4$</TEX>는 buffer 유입 후 용출되었다. 정제한 결과 <TEX>$A_4$</TEX>는 <TEX>$B_4$</TEX> 및 eye-specific <TEX>$C_4$</TEX>와 분자구조의 일부가 유사하였지만 <TEX>$B_4$</TEX>와 <TEX>$C_4$</TEX>는 서로 다른 것으로 나타났으므로, 하부단위체 A는 보존적이고, 하부단위체 B는 A보다 더 빠르게 진화된 것으로 보인다. 피루브산 10 mM에서 <TEX>$A_4$</TEX> 동위효소 39.98%, <TEX>$A_2B_2$</TEX> 21.28%, <TEX>$B_4$</TEX> 19.67% 및 eye-specific <TEX>$C_4$</TEX> 16.87%의 활성이 남아있었고, 피루브산에 대한 <TEX>$Km^{PYR}$</TEX>은 <TEX>$A_4$</TEX> 0.17 mM, <TEX>$B_4$</TEX> 0.27 mM, eye-specific <TEX>$C_4$</TEX> 0.133 mM였다. <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX>, eye-specific <TEX>$C_4$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$A_3B$</TEX> 및 <TEX>$AB_3$</TEX>의 최적 pH는 각각 pH 6.50, pH 8.5, pH 5.5, pH 6.0-6.5, 5.0 및 pH 7.5였고, 동질사량체 <TEX>$A_4$</TEX>와 이질사량체 동위효소들은 넓은 pH 영역에서 안정하였다. 특히 골격근은 LDH 활성이 크므로 활동성이 크며, 눈조직에서 피루브산 친화력이 강한 eye-specific <TEX>$C_4$</TEX>에 의해 피루브산 대사가 빠르게 일어나고, 이어서 <TEX>$A_4$</TEX>에 의해 젖산이 산화되어지는 것으로 사료되므로, 종의 생태환경 및 먹이 획득 양식에 따라 LDH-C 발현, 기질에 대한 친화도 및 대사 시간이 다른 것으로 사료된다. The lactate dehydrogenase (EC 1.1.1.27, LDH) isozymes in tissues from Channa argus were purified and characterized by biochemical, immunochemical and kinetic methods. The activity of LDH in skeletal muscle was the highest at 380.4 units and those in heart, eye and brain tissues were 13.4, 3,5 and 5.4 units, respectively. Citrate synthase (EC 4.1.3.7, CS) activity in heart tissue was the highest at 20.7 units. LDH/CS in skeletal muscle, heart, eye and brain tissues were 172.9, 0.6, 0.32 and 0.47. Protein concentration in skeletal muscle tissue was 14.7 mg/g and specific activities of LDH in skeletal muscle, heart, eye and brain tissues were 25.88, 0.79, 0.31 and 1.38 units/mg, respectively. Therefore, skeletal muscle tissue was anaerobic and heart tissue was aerobic. The LDH isozymes in tissues were identified by polyacrylamide gel electrophoresis, immunoprecipitation and Western blot with antiserum against <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX>, and eye-specific <TEX>$C_4$</TEX>. LDH <TEX>$A_4$</TEX>, <TEX>$A_3B$</TEX>, <TEX>$A_2B_2$</TEX>. <TEX>$AB_3$</TEX> and <TEX>$B_4$</TEX> isozymes were detected in every tissue, <TEX>$C_4$</TEX>, <TEX>$AC_3$</TEX>, <TEX>$A_2C_2$</TEX> and <TEX>$A_3C$</TEX> were detected in eye tissue, and <TEX>$A_3C$</TEX> was found in brain tissue. LDH <TEX>$A_4$</TEX>, <TEX>$A_3B$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$AB_3$</TEX>, <TEX>$B_4$</TEX>, eye-specific <TEX>$C_4$</TEX> isozymes were purified by affinity chromatography and Preparative PAGE Cells. The LDH <TEX>$A_4$</TEX> isozyme was purified in the fraction from elution with <TEX>$NAD^+$</TEX> containing buffer of affinity chromatography. Eye-specific <TEX>$C_4$</TEX> isozyme was eluted right after <TEX>$A_4$</TEX>, after which <TEX>$B_4$</TEX> isozyme was eluted with plain buffer. As a result, one part of molecular structures in <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX> and eye-specific <TEX>$C_4$</TEX> were similar, but were different from each other in <TEX>$B_4$</TEX> and <TEX>$C_4$</TEX>. Therefore the subunit A may be conservative in evolution, and the evolution of subunit B seems to be faster than that of subunit A. The activity of LDH <TEX>$A_4$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$B_4$</TEX>, and eye-specific <TEX>$C_4$</TEX> isozymes remained at 39.98, 21.28, 19.67 and 16.87% as a result of the inhibition by 10 mM of pyruvate, so the degree of inhibition was very high. The <TEX>$Km^{PYR}$</TEX> values were 0.17, 0.27 and 0.133 mM in <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX> and eye-specific <TEX>$C_4$</TEX> isozymes, respectively. The optimum pH of LDH <TEX>$A_4$</TEX>, <TEX>$B_4$</TEX>, eye-specific <TEX>$C_4$</TEX>, <TEX>$A_2B_2$</TEX>, <TEX>$A_3B$</TEX>, and <TEX>$AB_3$</TEX> were pH 6.5, pH 8.5, pH 5.5, pH 6.0-6.5, pH 5.0 and pH 7.5. The <TEX>$A_4$</TEX> and heterotetramer isozymes stabilized a broad range of pH. Especially, LDH activities in skeletal muscle tissue were high, resulting in a high degree of muscle activity.LDH metabolism in eye tissue seems to be converted faster from pyruvate to lactate by eye-specific <TEX>$C_4$</TEX> isozyme as eye-specific <TEX>$C_4$</TEX> have the highest affinity for pyruvate, and right after the conversion, oxidation of lactate was induced by <TEX>$A_4$</TEX> isozyme. It was found that expression of Ldh-C, affinity to substrate and reaction time of <TEX>$C_4$</TEX> isozyme were different according to the ecological environmental and feeding capturing patterns.

[Purpose]In this study, the authors have intended to investigate the effects that the exercise training and the intake of the water extract from propolis have on the activity of antioxidant enzymes.[Methods]For this purpose, the exercise training (70% VO2max treadmill running exercise for 60min)of 5 times per week for six weeks and the intake (50mg/kg/day) of the water extract from propolis were performed by separating the experimental animals (SD rats, n=32) into CON(n=8) group, CON+Ex(n=8), PA(n=8), and PA+Ex(n=8).[Results]As a result, the following conclusions were obtained: The concentration of the blood glucose and insulin of the CON+Ex group and PA+Ex group which are the exercise parallel group were significantly decreased in comparison with the control group, whereas if comparing the glycogen concentration in skeletal muscle and liver tissue between the exercise parallel group and the CON group, the former showed significantly high value in comparison with the latter (p < .05). In the case of the activity of the antioxidant enzyme in the skeletal muscle and the liver tissue, the activities of SOD, GPX and CAT in the gastrocnemius muscle tissue of the experimental animals showed significantly high value in PA+Ex group in comparison with other experimental groups (p < .05). In addition, the SOD activity in the liver tissue showed that only PA+Ex group was significantly increased, whereas GDX activity showed significantly higher value in CON+Ex group and PA group than CON group (p < .05). However, the activity of CAT in the liver tissue showed that there is no difference between the experimental groups. As a result that measured the concentration of MDA in order to evaluate the damage level of the tissue by oxygen free radicals, the difference between the groups in the liver tissue was not shown, while it was shown that only PA+Ex group in the skeletal muscle tissue was significantly decreased in comparison with other experimental groups (p < .05).[Conclusion]Taken together the above findings, it is considered that the parallel treatment of the exercise training and the water extract from propolis can not only increase the use of glycogen of the skeletal muscle and liver tissue, but also it can give the effect to suppress the creation of active oxygen by inducing the activity of the antioxidant enzyme in the body, and in the future, the possibility as the exercise supplements and the antioxidant of the water-soluble propolis are expected.

In addition to regulating cell motility, contractility, and cytokinesis, the actin cytoskeleton plays a critical role in the regulation of transcription and gene expression. We have previously identified a novel muscle-specific actin-binding protein, STARS (striated muscle activator of Rho signaling), which directly binds actin and stimulates serum-response factor (SRF)-dependent transcription. To further dissect the STARS/SRF pathway, we performed a yeast two-hybrid screen of a skeletal muscle cDNA library using STARS as bait, and we identified two novel members of the ABLIM protein family, ABLIM-2 and -3, as STARS-interacting proteins. ABLIM-1, which is expressed in retina, brain, and muscle tissue, has been postulated to function as a tumor suppressor. ABLIM-2 and -3 display distinct tissue-specific expression patterns with the highest expression levels in muscle and neuronal tissue. Moreover, these novel ABLIM proteins strongly bind F-actin, are localized to actin stress fibers, and synergistically enhance STARS-dependent activation of SRF. Conversely, knockdown of endogenous ABLIM expression utilizing small interfering RNA significantly blunted SRF-dependent transcription in C2C12 skeletal muscle cells. These findings suggest that the members of the novel ABLIM protein family may serve as a scaffold for signaling modules of the actin cytoskeleton and thereby modulate transcription.

Skeletal muscle comprises a family of diverse tissues with highly specialized morphology, function, and metabolism. Many acquired diseases – including HIV, COPD, cancer cachexia, critical illness myopathy, and sepsis – affect specific muscles while sparing others. Even monogenic muscular dystrophies tend to selectively affect certain muscle groups, despite their causative genetic mutations being present in all tissues. These observations suggest that factors intrinsic to muscle tissues influence their susceptibility to various disease mechanisms. Nevertheless, most studies have not addressed transcriptional diversity among skeletal muscles. Here we use unbiased RNA sequencing (RNAseq) to profile global mRNA expression in a wide array of skeletal, smooth, and cardiac muscle tissues from mice and rats. Our data set, MuscleDB, reveals extensive transcriptional diversity, with greater than 50% of transcripts differentially expressed among skeletal muscle tissues. This diversity is only partly explained by fiber type composition and developmental history, suggesting that specialized transcriptional profiles establish the functional identity of muscle tissues. We find conservation in the transcriptional profiles across species as well as between males and females, indicating that these data may be useful in predicting gene expression in related species, such as humans. Notably, thousands of differentially expressed genes in skeletal muscle are associated with human disease, and hundreds of these genes encode targets of drugs on the market today. Related to this observation, we suggest a mechanistic explanation for how myotonic dystrophy induces weakness in the extensor digitorum longus (EDL) while sparing nearby muscles. These data may therefore provide the means by which muscle-specific sensitivity to disease may be unraveled. In addition, we detect hundreds of putative myokines that may underlie the endocrine functions of skeletal muscle. We anticipate that in conjunction with transcriptional modeling, this resource will catalyze more sophisticated tissue engineering of skeletal muscle to improve the efficacy of regenerative medicine.

Resveratrol Supplementation Does Not Improve Metabolic Function in Nonobese Women with Normal Glucose Tolerance

Gene expression analyses based on messenger RNA (mRNA) profiling require accurate data normalisation. When using endogenous reference genes, these have to be validated carefully. Therefore, we examined the transcript stability of 10 potential reference genes using quantitative real-time polymerase chain reaction: beta actin, 18S rRNA, glyceraldehyde-3-phosphate dehydrogenase, TATA box-binding protein, hypoxanthine phosphoribosyl-transferase I, beta-2-microglobulin, hydroxymethylbilane synthase, succinate dehydrogenase complex, subunit A, cyclophilin A and ubiquitin C. The aim of the current study was to assess which reference genes show stable mRNA levels in human post mortem cardiac muscle, skeletal muscle and brain tissue. Considering cardiac muscle tissue, CYCA and TBP were identified as the most stable while in skeletal muscle tissue, SDHA and TBP, and in brain tissue, SDHA and HMBS turned out to be the most stable. Furthermore, we recommend a minimum of four carefully validated endogenous control genes for reliable data normalisation in human post mortem tissue. Parameters influencing the stability of transcript amounts were found to be mainly the post mortem interval in cardiac muscle and skeletal muscle tissue and the donor's cause of death in skeletal muscle and brain samples. Further parameters like gender, age at death and body mass index were found to influence mRNA quantities in skeletal muscle only. The set of stable control genes identified in this study may be used in further studies if the composition of the samples is similar to the one used here.

The body’s musculature is both quantitatively and qualitatively of critical importance to the body. In an average human, the muscle takes up a third to half of all the body mass. Qualitatively, it is critical to all aspects of life; even the brain has virtually no other means of expressing its thoughts other than by contraction of muscle fibers. Two main distinct muscle tissues are present in the body, smooth and striated muscle tissue. Striated muscle tissue is subdivided into two major parts: skeletal muscle tissue and cardiac muscle tissue. In the muscular dystrophies, both skeletal and cardiac muscle tissues are part of the pathological manifestation of disease. In this chapter, we will discuss the basic mechanism of contraction at the molecular level, as well as the regulatory mechanisms that make the muscle function in vivo. We will focus on skeletal muscle and cardiac muscle, briefly describing the extent to which muscular dystrophy impacts muscle contraction in these two different muscle tissues.

1. Microdialysis was used to gain insight into the substrate exchanges in the interstitial space of skeletal muscle and adipose tissue. Probes were inserted in the quadriceps femoris muscle and para-umbilical subcutaneous adipose tissue of thirteen subjects and microdialysis was performed at different flow rates (1-4 microliters min-1) and during changes in tissue blood flow. 2. When ethanol (5 mM) is included in the perfusion solution, the ethanol clearance from the probe is a measure of tissue blood flow. Blood flow changes induced by adenosine or vasopressin perfusion, by exercise or by circulatory occlusion resulted in ethanol clearance values of 69-139% of the basal level. The ethanol clearance was higher in skeletal muscle than in adipose tissue (32-62%, P < 0.001), a difference compatible with a higher blood flow in muscle tissue. 3. The fraction of the interstitial glucose concentration that was recovered with the microdialysis was similar in skeletal muscle (the absolute values being 1.70 +/- 0.14 mM at 1 microliter min-1 and 0.59 +/- 0.05 mM at 4 microliters min-1) and adipose tissue (1.89 +/- 0.20 mM at 1 microliter min-1; 0.54 +/- 0.05 mM at 4 microliters min-1) and correlated inversely with the tissue ethanol clearance, both in the basal state and during changes in tissue blood flow (muscle: r = -0.56 to -0.67; adipose tissue r = -0.72 to -0.95). Coefficients of variation were 6-8% (glucose) and 11-16% (lactate) and were similar during isometric exercise. The reproducibility of the technique (comparison of two contralateral probes; perfusion flow rate 4 microliters min-1) was 5.3-8.3% (ethanol) and 23.9-20.8% (glucose) in muscle (n = 6) and adipose tissue (n = 4) respectively. 4. The skeletal muscle dialysate lactate concentration (1 microliter min-1: 1.16 +/- 0.2 mM) was higher than in adipose tissue (0.76 +/- 0.08 mM, P < 0.05), where the absolute amount of lactate that could be removed from the tissue (at 4 microliters min-1) was only half of that in skeletal muscle (0.8 +/- 0.11 vs. 1.76 +/- 0.23 nmol min-1, P < 0.05). The dialysate lactate level was not affected in either tissue by large changes in the interstitial glucose concentration indicating that in neither tissue is blood glucose a significant source of lactate formation. 5. The blood flow effects on the dialysate glucose concentration are the likely consequence of probe glucose drainage artificially shifting the balance between the supply and consumption of interstitial glucose.(ABSTRACT TRUNCATED AT 400 WORDS)

In recent years, the effect of vibration applications on the endocrine system is a subject which has been discussed. Studies have shown that muscle contractions cause some responses in the endocrine system. This study aimed to determine the effects of whole body vibration (WBV) exercise applied at different environmental temperatures on the distribution of the irisin in muscle tissue. In our study, 30 healthy and adult female rats were used. Rats were divided into four groups as a control group (n = 6) and three different experimental groups (n = 8). 1st experimental group at 15 ± 0.5˚C, 2nd experimental group in normal room conditions, 3rd the experimental group at 35 ± 0.5˚C applied WBV exercise 5 sessions a week, 20 minutes in each session for 4 weeks. The control group rats were kept in vibration cassettes at normal room temperature, with the same number and duration of sessions, without WBV exercise. After all experimental procedures were completed, samples of skeletal muscle (M.gastrocnemius) tissue taken from the rats in the groups were used as material. When the localization and distribution of irisin in the skeletal muscle tissue were examined, it was determined that irisin was secreted from both muscle fibers and connective tissue in all groups, and the concentration of irisin synthesized from muscle fiber was the highest in the 3rd experimental group (p &lt; 0.05). As a result, in this study, WBV exercise applied in a hot environment increases the level of irisin in muscle tissue more than WBV exercise applied in a cold environment and at room temperature.

BackgroundWith the increasing number of studies on osteoporosis and muscle adipose tissue, existing studies have shown that skeletal muscle tissue and adipose tissue are closely related to osteoporosis by dual-energy x-ray absorptiometry (DXA) measurement. However, few studies have explored whether the skeletal muscle and adipose tissue index measured at the lumbar spine 3 (L3) level are closely related to bone mineral density (BMD) and can even predict osteoporosis. Therefore, this study aimed to prove whether skeletal muscle and adipose tissue index measured by computed tomography (CT) images based on a single layer are closely related to BMD.MethodsA total of 180 participants were enrolled in this study to obtain skeletal muscle index (SMI), psoas muscle index (PMI), subcutaneous fat index (SFI), visceral fat index (VFI), and the visceral-to-subcutaneous ratio of the fat area (VSR) at L3 levels and divide them into osteoporotic and normal groups based on the T-score of DXA. Spearman rank correlation was used to analyze the correlation between SMI, PMI, SFI, VFI, VSR, and BMD. Similarly, spearman rank correlation was also used to analyze the correlation between SMI, PMI, SFI, VFI, VSR, and the fracture risk assessment tool (FRAX). Receiver operating characteristic (ROC) was used to analyze the efficacy of SMI, PMI, SFI, VFI, and VSR in predicting osteoporosis.ResultsBMD of L1-4 was closely correlated with SMI, PMI, VFI and VSR (r = 0.199 p = 0.008, r = 0.422 p < 0.001, r = 0.253 p = 0.001, r = 0.310 p < 0.001). BMD of the femoral neck was only correlated with PMI and SFI (r = 0.268 p < 0.001, r = − 0.164 p-0.028). FRAX (major osteoporotic fracture) was only closely related to PMI (r = − 0.397 p < 0.001). FRAX (hip fracture) was closely related to SMI and PMI (r = − 0.183 p = 0.014, r = − 0.353 p < 0.001). Besides, FRAX (major osteoporotic fracture and hip fracture) did not correlate with VFI, SFI, and VSR. SMI and PMI were statistically significant, with the area under the curve (AUC) of 0.400 (95% confidence interval 0.312-0.488 p = 0.024) and 0.327 (95% confidence interval 0.244-0.410 p < 0.001), respectively. VFI, SFI, and VSR were not statistically significant in predicting osteoporosis.ConclusionsThis study demonstrated that L3-based muscle index could assist clinicians in the diagnosis of osteoporosis to a certain extent, and PMI is superior to SMI in the diagnosis of osteoporosis. In addition, VFI, SFI, and VSR do not help clinicians to diagnose osteoporosis well.