Muscle Fiber Hyperplasia Research Articles

A rare case of Wilkie`s syndrome with infantile hypertrophic pyloric stenosis

Wilkie’s syndrome is a rare clinical disorder characterized by partial or complete obstruction of the duodenum. Infantile hypertrophic pyloric stenosis (IHPS) is defined as hyperplasia of the smooth muscle fibers of the pylorus, which is considered responsible for narrowing the pyloric canal and eventually obstructing the gastric outlet. This paper presents a case of a 3-month-old boy who had been vomiting after feeding for one month. The main symptoms, postprandial vomiting, dehydration, alkalosis, and weight reduction, point to the IHPS disease. Imaging studies also confirmed the diagnosis. During the surgical treatment, a concomitant condition known as Wilkie’s syndrome was also evidenced. The team performed a complex surgical treatment of a patient diagnosed with both Wilkie’s syndrome and IHPS within one single surgical operation. Surgical treatment with pyloromyotomy and duodenal-duodenal anastomosis within one operation is an optimal option for one-stage treatment of patients with IHPS and Wilkie’s syndrome.

Multi-omics reveals the molecular mechanism of muscle quality changes in common carp (Cyprinus carpio) under two aquaculture systems

Preliminary experiments in our laboratory have demonstrated that common carp (Cyprinus carpio) cultivated for two months in land-based container recirculating aquaculture systems (C-RAS) exhibit superior muscle quality compared to those raised in traditional pond systems (TP). To elucidate the molecular mechanisms underlying muscle quality variations in common carp cultured under two aquaculture systems, transcriptomic and metabolomic analyses were performed on muscle tissues of specimens aged 11 to 23 months. Comparison of muscle histological sections between the two groups indicated a significantly lower long diameter of muscle fibers in the C-RAS group compared to the TP group (P < 0.01). Conversely, the muscle fiber density was significantly higher in the C-RAS group than in the TP group (P < 0.05). Transcriptomic and metabolomic analyses identified 3390 differentially expressed genes (DEGs)—1558 upregulated and 1832 downregulated—and 181 differentially expressed metabolites (DEMs)—124 upregulated and 57 downregulated—between the groups. Based on integrated transcriptomic and metabolomic analyses, the significant differences focus on metabolic pathways involving glycolysis/gluconeogenesis, arginine and proline metabolism, arginine biosynthesis, and purine metabolism. The study revealed that the muscle quality of common carp in two aquaculture systems is primarily regulated through improvements in energy metabolism, amino acid metabolism, fatty acid metabolism, and purine metabolism. These metabolic processes play significant roles in promoting muscle fiber hyperplasia and hypertrophy, enhancing muscle flavor, and increasing muscle antioxidant capacity. This study provides new insights into the molecular and metabolic pathways that control muscle quality in common carp under different environmental factors.

Histopathological staging of atrophic lesions of gastric mucosa

ObjectiveTo study the histopathological staging of atrophic lesions of the gastric mucosa. MethodsHistology and immunohistochemistry were used to closely examine 2144 specimens of atrophic gastric mucosa that were taken from endoscopic biopsies. ResultsWhen the gastric mucosa epithelium is affected by infection, chemical stimulation, immune factors, genetic factors, and other factors, it may cause an atrophy of gastric mucosa epithelium and a decrease in the number of glands, intestinal metaplasia, hyperplasia of smooth muscle fibers, and atrophy of stem cells in the proliferative zone. In this study, we characterized the above lesions as atrophic lesions of the gastric mucosa. Based on the morphological and histological characteristics of the lesion, as well as the law of cell proliferation and transformation during its occurrence and development, we propose five stages. We also noted the onset age, gender correlation, and histopathological characteristics of each stage of gastric mucosal atrophies. ConclusionUnderstanding the pathological staging of gastric mucosal atrophy is essential for treating patients correctly and keeping track of changes in malignant cells. It is also very important in preventing the initiation of gastric cancer or from getting worse.

Dietary creatine promotes creatine reserves, protein deposition, and myofiber hyperplasia in muscle of juvenile largemouth bass (Micropterus salmoides)

Creatine can increase muscle mass, enhance performance, prevent disease-induced muscle atrophy, and improve overall cellular energy. This study investigated the effects of creatine as a feed additive on muscle growth and intrinsic molecular regulation mechanism in largemouth bass (Micropterus salmoides). Seven diets supplemented with different concentrations of creatine (0%, 0.1%, 0.25%, 0.5%, 1%, 2%, and 4%) were fed to juvenile largemouth bass (4.5–5.1 g) for eight weeks. Dietary creatine significantly increased body weight and body length, and reduced feed conversion ratio. High-performance liquid chromatography analysis revealed that dietary creatine addition notably increased creatine and phosphocreatine levels by 19.94% and 16.54% in the muscle of largemouth bass, respectively. Histological observation showed that dietary creatine significantly increased the total muscle fiber number and decreased the mean muscle fiber diameter. The Western blot results indicated that creatine ingestion significantly increased the protein level of MyoD1 in the muscle and promoted muscle fiber hyperplasia. In addition, dietary creatine also contributed to mTOR-S6K/4EBP1-mediated protein synthesis by maintaining AMPKα Thr172 dephosphorylation and AKT Thr308 phosphorylation. Moreover, the protein levels of the muscle-specific E3 ligases Atrogin1 and Murf1 responsible for ubiquitination degradation exhibited no significant change after feeding with creatine in largemouth bass. Overall, our data showed that creatine as a feed additive increased creatine and phosphocreatine contents, thus promoting muscle protein deposition and myofiber hyperplasia, eventually elevating growth performance and feed utilization efficiency in juvenile largemouth bass. The regression analysis of weight gain rate, specific growth rate, and feed conversion ratio determined 0.46%–0.54% creatine concentration range as optimal supplementation concentration for the culture of juvenile largemouth bass.

33 Identification of How Future Climates May Impact the Reproductive Herd and What This May Mean for Nutrition

Abstract Changes in our climate with global warming will translate to an expansion in the seasons and an increased incidence of extreme heat events, such that heat stress (HS) will become a major management issue. This poses particular challenges to the reproductive herd, as by virtue of their increased physical size and pregnancy, they are less resilient to environmental challenges. Recent work from our laboratory has quantified the performance of summer mated piglets on productivity, demonstrating that these litters are lighter at birth, have a lighter placenta weight and are more likely to be stillborn. These piglets also take longer to reach market weight and have increased carcass backfat, which can trigger market penalties. Collectively our studies demonstrate that summer conditions result in developmental abnormalities in piglets, potentially through placental insufficiency. Additionally, HS was challenging sows during the periparturient period, resulting in more stillbirths. Two subsequent climate-controlled studies quantified the effects of HS (cyclic 28 to 33 oC) during early to mid-pregnancy (d 40 to 60), when the placenta is undergoing rapid growth, as well as the effects of HS (cyclic 28 to 30 oC) in the periparturient period (d 110 of pregnancy to farrowing). In the first study, gestational HS did not influence the number or size of the piglets at mid-gestation but increased placental mass by 22% and reduced Longissimus muscle fiber hyperplasia by 16%. The apparent enlargement of the placenta at mid-gestation may reflect an adaptation to a reduction in uterine blood flow. In other species, HS is known to reduce blood flow to the splanchnic bed and reproductive tract organs, as blood is redistributed to the periphery and upper respiratory tract to augment heat dissipation. Therefore, the prioritization of placental growth by the piglet may represent an adaptation against a backdrop of insufficient nutrient supply. Whilst reductions in muscle fiber hyperplasia were associated with reduced vascularity, although it is not clear if this was a cause or effect. In the second study, the effects of periparturient HS resulted in a 30% increase in stillbirths, with surviving piglets having lower umbilical vein blood oxygen saturation and increased meconium staining. This supports the likelihood of HS restricting uterine and umbilical blood flows, resulting in increased periparturient fetal stress. Collectively these studies emphasize the challenges that climate change poses to swine production and that addressing these challenges will require a whole farm approach. In the near term, it is likely that advances in nutrition will form an important component in adjusting to a changing climate and minimize production losses.

Morphological and functional changes in the skeletal muscles of the hind limbs in rats under enforced anaerobic physical exertion and allogeneic biomaterial application

Exhausting physical activity leads to sarcomere overstrain, destruction of the cell membrane, hydrolysis of structural proteins, thus, resulting in irreversible damage to muscle fibers. Allogeneic biomaterial (AB) is applied to regenerate various tissues and organs. The aim of the study was to identify morphofunctional features of the skeletal muscle tissue after physical exertion and under AB application. Material and methods. This experimental study involved male Wistar rats. Anaerobic physical exertion was simulated using the Porsolt test with a load equal 10 % of the body weight for 30 days. After training, animals of the main group (n = 10) were injected AB suspension: 4 ml of a 0.2 % solution into the muscles of the fore and hind limbs totally. Animals of the control group (n = 10) received physiological saline into similar zones. Tolerant load was investigated in 5 and 21 days after injection. Then the animals were withdrawn from the experiment, and muscles of the hind limbs were studied histologically, the total number, the average cross-sectional area of muscle fibers, and the number of necrotic fibers were measured. Results. In 5 and 21 days animals from the control group manifested dystrophic changes in muscle fibers: type III, IV contractures, microcirculation disorders, mosaic necrosis of muscle fibers, inflammatory cell infiltration, and a decreased tolerant load. In 21 days fibrosis was detected. The AB introduction provided rhabdomyogenesis as soon as in 5 days. Inflammatory cell infiltration decreased, the polygonality of muscle fiber profiles was restored, and edematous phenomena were leveled. There was hyperplasia of muscle fibers, a decreased number of necrotic muscle fibers, inhibited fibrosis, and an increased tolerant load. AB further biodegraded. Conclusion. AB contributed to the reduced manifestations of dystrophic changes in muscle fibers, strengthened actoprotective mechanism, and restored physical activity in the early stages.

Dual single guide RNAs-mediating deletion of mature myostatin peptide results in concomitant muscle fibre hyperplasia and adipocyte hypotrophy in pigs

Myostatin (MSTN) is a major gene target for skeletal muscle overgrowth in animals. We hypothesized that deletion of the entire mature peptide encoded by MSTN in pigs would knock out its bioactive form and accordingly stimulate skeletal muscle overgrowth. Thus, we engineered two pairs of single-guide RNAs (sgRNAs) to target exons 1 and 3 of MSTN in primary fetal fibroblasts of Taoyuan black pigs. We found that sgRNAs targeting exon 3, which encodes the mature peptide, had higher biallelic null mutation efficiency than those targeting exon 1. Somatic cell nuclear transfer was conducted using the exon 3 mutation cells as donor cells to generate five cloned MSTN null piglets (MSTN−/−). Growth testing revealed that both the growth rate and average daily weight gain of MST−/− pigs were greater than those of wild-type (MSTN+/+) pigs. Slaughter data demonstrated that the lean ratio of MSTN−/− pigs was 11.3% higher (P < 0.01) while the back-fat thickness was 17.33% lower (P < 0.01) than those of MSTN+/+ pigs. Haematoxylin–eosin staining indicated that the increased leanness of MSTN−/− pigs resulted from muscle fibre hyperplasia rather than hypertrophy.HE staining showed markedly decreased adipocyte size in MSTN−/− pigs. We also critically examined the off-target and random integration by resequencing, which showed that the founder MSTN−/− pigs contained no non-target mutations or exogenous plasmid elements. This study is the first to report the successful knock out of the mature MSTN peptide using dual sgRNA-mediated deletion, leading to the most prominent alteration of meat production traits in pigs published thus far. This new strategy is expected to have a wide impact on genetic improvements in food animals.

Morphological features and histological structure of the musculature of two trout phenotypic forms when reared in warm water of a power plant

The paper studies the effect of rearing in stocking ponds using the warm discharge water of the Smolensk NPP on the growth and trout meat quality. Some morphological indicators of trout cultivation are presented. The histological studies of the musculature of golden and typically colored trout are presented. It was revealed that the golden trout musculature grows with a predominance of hyperplasia of muscle fibers compared to the typically colored trout. It was shown that trout rearing using NPP cooling ponds does not lead to excessive accumulation internal fat and gives good results.

Comparative genome-wide methylation analysis reveals epigenetic regulation of muscle development in grass carp (Ctenopharyngodon idellus) fed with whole faba bean.

Crisp grass carp (CGC), the most representative improved varieties of grass carp (GC), features higher muscle hardness after feeding faba bean (Vicia faba L.) for 90-120 days. DNA methylation, a most widely studied epigenetic modification, plays an essential role in muscle development. Previous studies have identified numerous differentially expressed genes (DEGs) between CGC and GC. However, it remains unknown if the expression levels of these DEGs are influenced by DNA methylation. In the present study, we performed a comprehensive analysis of DNA methylation profiles between CGC and GC, and identified important candidate genes related to muscle development coupled with the transcriptome sequencing data. A total of 9,318 differentially methylated genes (DMGs) corresponding to 155,760 differentially methylated regions (DMRs) were identified between the two groups under the CG context in promoter regions. Combined with the transcriptome sequencing data, 14 key genes related to muscle development were identified, eight of which (gsk3b, wnt8a, wnt11, axin2, stat1, stat2, jak2, hsp90) were involved in muscle fiber hyperplasia, six of which (tgf-β1, col1a1, col1a2, col1a3, col4a1, col18a1) were associated with collagen synthesis in crisp grass carp. The difference of methylation levels in the key genes might lead to the expression difference, further resulting in the increase of muscle hardness in crisp grass carp. Overall, this study can help further understand how faba bean modulates muscle development by the epigenetic modifications, providing novel insights into the texture quality improvement in other aquaculture fish species by nutritional programming.

224 Awardee Talk: Investigating Muscle Fiber Hypertrophy During pre- and Post-Natal Growth

Abstract Research has established that muscle fiber hyperplasia is complete during mid gestation; therefore, skeletal muscle fiber hypertrophy is responsible for the increase in muscle mass observed during late gestation and postnatal growth periods. Our research is investigating key times points during muscle fiber hypertrophy and the role of miRNA and mRNA transcriptome in this process. Two studies were conducted to examine changes in muscle mass, muscle fiber hypertrophy, and gene expression from gestational d (gd) 85 to market weight in Suffolk or Texel cross lambs. Longissimus muscle (LM) samples were taken for muscle fiber histology at the following time points: gd85, gd110, gd133, and market (d243) in study one and at postnatal d2, d14 and d203 in study two. microRNA (miRNA) and mRNA sequencing of the LM were conducted in study one and included biopsies at d 42 and 65. Type I and Type II muscle fiber area increased (P &amp;lt; 0.05) at each stage of growth evaluated. Type I muscle fiber area increased by 26.7-fold and Type II muscle fiber area increased by 37.4-fold from gd85 to market (d243). mRNA sequencing identified a total of 9360 unique genes differentially expressed (DEGs; P &amp;lt; 0.05) in LM during hypertrophic growth but the majority of DEGs were observed in the prenatal (51%) and early postnatal (54%) periods. There were 142 unique miRNAs differentially expressed (P &amp;lt; 0.05) during hypertrophic growth of LM but the majority (62%) were observed in the transition period from prenatal to postnatal growth. Overall, muscle fiber hypertrophy is dynamic from late gestation through postnatal growth, but transcriptomic changes indicate key time periods during development in which mechanisms underlying hypertrophic growth may be altered.

Gestational heat stress alters skeletal muscle gene expression profiles and vascularity in fetal pigs in a sexually dimorphic manner

BackgroundThere is evidence that sow heat stress (HS) during gestation affects fetal development with implications for impaired muscle growth. We have previously demonstrated that maternal HS during early to mid-gestation compromised muscle fibre hyperplasia in developing fetal pigs. Thus, we hypothesised these phenotypic changes are associated with a change in expression of genes regulating fetal skeletal muscle development and metabolism. To test this, at d 60 of gestation, RNA sequencing and immunohistochemistry were performed on fetal longissimus dorsi (LD) muscle biopsies collected from pregnant gilts that had experienced either thermoneutral control (CON, 20 °C, n = 7 gilts, 18 LD samples) or controlled HS (cyclic 28 to 33 °C, n = 8 gilts, 23 LD samples) conditions for 3 weeks.ResultsA total of 282 genes were differentially expressed between the HS and CON groups in female LD muscles (false discovery rate (FDR) ≤ 0.05), whereas no differentially expressed genes were detected in male LD muscles between the two groups (FDR > 0.05). Gestational HS increased the expression of genes associated with transcription corepressor activity, adipogenesis cascades, negative regulation of angiogenesis and pro-inflammatory signalling in female LD muscles. Immunohistochemical analyses revealed a decreased muscle vascularity density in fetuses from HS group for both sexes compared to those from the CON group (P = 0.004).ConclusionsThese results reveal gilt HS during early to mid-gestation altered gene expression profiles in fetal LD muscles in a sexually dimorphic manner. The molecular responses, including transcription and angiogenesis repressions and enhanced adipogenesis cascades, were exclusively observed in females. However, the associated reductions in muscle vascularity were observed independently of sexes. Collectively this may indicate female fetal pigs are more adaptive to gestational HS in terms of gene expression changes, and/or there may be sexually dimorphic differences with respect to the timing of muscle molecular responses to gestational HS.

Natural evolution of perforating wounds of 30% extension of the left diaphragm and the anatomopathological characteristics of its healing. Experimental Study.

diaphragmatic injury is a challenge for surgeons. It is an injury that can be isolated. It is frequent in penetrating thoracoabdominal trauma. It represents a diagnostic challenge and the ideal approach is not yet well established. The occurrence of spontaneous healing of these injuries is still much discussed and even more, if it does, what is the healing mechanism? to macroscopically and histologically evaluate the natural evolution of perforation and cutting wounds equivalent to 30% of the left diaphragm. 50 specimens of rats underwent a surgical procedure and, after 30 days, were euthanized and those that presented scar tissue in the diaphragm, the samples were submitted to histopathological study, using the hematoxylin and eosin stains, Massons trichrome and Picrosirius to assess the presence of collagen or muscle fibers (hyperplasia) in the scar. it was found that healing occurred in diaphragmatic injuries in 90% of rats. We also observed the presence of fibrosis in all analyzed samples. Spontaneous healing occurred in most diaphragmatic injuries and the inflammatory reaction represented by the presence of fibrosis and collagen deposition was observed in all our samples. Muscle fiber hyperplasia did not occur.

Клінічний випадок гострої кишкової непрохідності під час вагітності в пацієнтки з ектракорпоральним заплідненням та великим інтергенетичним інтервалом

The great importance in the development of acute intestinal obstruction (AIO) is the change in intestinal kinetics during pregnancy. In pregnant women, the rhythmic function of the intestine slows down due to an increase in the threshold of excitability of its receptors to biologically active substances. The article provides an overview of modern literary sources on the problem of acute intestinal obstruction in pregnant women. According to foreign literature sources, the incidence of intestinal obstruction in pregnant women is 1:3600–1:66000, and complications of diseases of the digestive system rank 4th among the causes of maternal mortality during pregnancy — 9%. According to domestic scientific sources, the frequency with which intestinal obstruction occurs in pregnant women is 1:40000–1:50000 births, mortality reaches 35–50%, stillbirth — 60–75%. The development of the disease is caused by physiological changes in the body of a pregnant woman. With increasing gestational age there are changes in the anatomical arrangement of the abdominal organs. From the second trimester of pregnancy, the uterus extends beyond the pelvis and gradually occupies the entire abdominal cavity. The increase in the size of the uterus due to hypertrophy and hyperplasia of muscle fibers, amniotic fluid, fetal growth, leads to increased intraabdominal pressure, displacement of the small intestine and lumbar colon up, thereby creating conditions for compression of intestinal loops, nodules, development. The modern classification, clinic, diagnostics and methods of treatment of this surgical pathology are presented. The author presents his own clinical case of acute intestinal obstruction in a 51-year-old pregnant woman with the sixth desired pregnancy, which occurred as a result of assisted reproductive technologies and a large intergenetic interval. Both surgeon and obstetrician-gynecologist treat intestinal obstruction in pregnant women. Conservative treatment is carried out simultaneously with diagnostic procedures. No effect of conservative therapy for 2 hours is an indication for surgery. The main purpose of surgery is to eliminate the causes of intestinal obstruction and restore bowel function. The scope of surgery is determined in each case individually and depends on the type of AIO and the age of the disease. The chosen tactics of the preoperative period, the volume of surgery, anesthesia and adequate management of the postoperative period can cure acute surgical pathology, maintain the desired pregnancy, avoid the development of obstetric and surgical purulent-septic complications. The research was carried out in accordance with the principles of the Helsinki declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: sharp bowel obstruction, pregnancy, extracorporal impregnation, large intergenic interval.

High lipid and high carbohydrate diets affect muscle growth of blunt snout bream (Megalobrama amblycephala) through different signaling pathways

The study was carried out to explore the effect of high lipid/carbohydrate diet on muscle growth of Megalobrama amblycephala. In vivo, three experimental diets, a control diet (6% lipid and 28.13% carbohydrate, CD), a high lipid diet (11%lipid，HLD) and a high carbohydrate diet (39.6% carbohydrate, HCD), were formulated and randomly fed to Megalobrama amblycephala (average initial weight 19.80 ± 0.15 g) for 12 weeks. The results showed that there was no significant difference in specific growth rate (SGR) and weight gain rate (WGR) between the control diet group and the high energy diets group (P > 0.05). The springiness, gumminess, chewiness and muscle fiber density were significantly up-regulated in the high energy diets group than control diet group (P < 0.05). HLD, compared with HCD, significantly increased the muscle fiber cross-sectional area (CSA) and muscle fiber diameter in the white muscle (P < 0.05). High energy diets significantly elevate the transcriptional levels of Myf5, Myog and Mrf4, and reduce the transcriptional levels of MSTNa and MSTNb (P < 0.05). The transcriptional levels and protein expressions of AMPK and Sirt1 were significantly elevated in the HLD group (P < 0.05). The CAMK and CAN protein levels were significantly increased in the HCD group (P < 0.05). In vitro, the isolated primary hepatocytes from Megalobrama amblycephala were coincubated with 0.4 mM oleic acid (OA) and 40 mM d-glucose respectively. The results clearly state that 0.4 mM OA significantly increased the transcriptional levels of AMPKα1, AMPKα2 and Sirt1, the protein level of AMPK, p-AMPK, p-AMPK/AMPK and Sirt1 (P < 0.05). The protein expression of CAMK and CAN in hepatocytes treated with 40 mM d-glucose were significantly higher than that in the other two treatments (P < 0.05). In summary, high energy diets promoted the muscle fiber hyperplasia in Megalobrama amblycephala while high lipid and high carbohydrate diets may affect muscle growth through AMPK/Sirt1 pathway and Ca2+-dependent pathway, respectively.

Deciphering Myostatin's Regulatory, Metabolic, and Developmental Influence in Skeletal Diseases.

Current research findings in humans and other mammalian and non-mammalian species support the potent regulatory role of myostatin in the morphology and function of muscle as well as cellular differentiation and metabolism, with real-life implications in agricultural meat production and human disease. Myostatin null mice (mstn−/−) exhibit skeletal muscle fiber hyperplasia and hypertrophy whereas myostatin deficiency in larger mammals like sheep and pigs engender muscle fiber hyperplasia. Myostatin’s impact extends beyond muscles, with alterations in myostatin present in the pathophysiology of myocardial infarctions, inflammation, insulin resistance, diabetes, aging, cancer cachexia, and musculoskeletal disease. In this review, we explore myostatin’s role in skeletal integrity and bone cell biology either due to direct biochemical signaling or indirect mechanisms of mechanotransduction. In vitro, myostatin inhibits osteoblast differentiation and stimulates osteoclast activity in a dose-dependent manner. Mice deficient in myostatin also have decreased osteoclast numbers, increased cortical thickness, cortical tissue mineral density in the tibia, and increased vertebral bone mineral density. Further, we explore the implications of these biochemical and biomechanical influences of myostatin signaling in the pathophysiology of human disorders that involve musculoskeletal degeneration. The pharmacological inhibition of myostatin directly or via decoy receptors has revealed improvements in muscle and bone properties in mouse models of osteogenesis imperfecta, osteoporosis, osteoarthritis, Duchenne muscular dystrophy, and diabetes. However, recent disappointing clinical trial outcomes of induced myostatin inhibition in diseases with significant neuromuscular wasting and atrophy reiterate complexity and further need for exploration of the translational application of myostatin inhibition in humans.

Commentary on: Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

Commentary on: Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

BackgroundHigh-intensity focused electromagnetic (HIFEM) field technology has been reported to increase muscle thickness and hypertrophy. However, this process has not yet been confirmed on a histologic level.ObjectivesThe aim of this study was to evaluate in-vivo structural changes in striated porcine muscle tissue following HIFEM treatment.MethodsThree Yorkshire pigs received four 30-minute HIFEM treatments applied to the biceps femoris muscle on 1 side only. The fourth pig served as a control subject. At baseline and 2 weeks after the last treatment, biopsy specimens of the muscle tissue were collected from the treatment site. The control pig underwent muscle biopsy from a similar but untreated site. Twenty-five histology slides were evaluated from each pig. A certified histopathologist analyzed sliced biopsy samples for structural changes in the tissue.ResultsHistologic analysis showed hypertrophic changes 2 weeks posttreatment. The muscle mass density increased by 20.56% (to a mean of 17,053.4 [5617.9] µm2) compared with baseline. Similarly, muscle fiber density (hyperplasia) increased: the average change in the number of fibers in a slice area of 136,533.3 µm2 was +8.0%. The mean size of an individual muscle fiber increased by 12.15% (to 332.23 [280.2] µm2) 2 weeks posttreatment. Control samples did not show any significant change in fiber density or hyperplasia.ConclusionsHistopathologic quantification showed significant structural muscle changes through a combination of fiber hypertrophy and hyperplasia. Control biopsies showed a lack of similar changes. The data correlate with findings of other HIFEM research and suggest that HIFEM could be used for noninvasive induction of muscle growth.

Exogenous Expression of an Alternative Splicing Variant of Myostatin Prompts Leg Muscle Fiber Hyperplasia in Japanese Quail.

Myostatin (MSTN) negatively regulates muscle growth and development through inhibiting myoblast proliferation and differentiation. Five alternative splicing isoforms of MSTN (MSTN-A to MSTN-E) have been discovered in domestic avian species. MSTN-A has high expression in skeletal muscle and encodes the full-length peptide with anti-myogenic activity. Another isoform, MSTN-B, is also highly expressed in skeletal muscle and encodes a truncated peptide that has pro-myogenic capabilities in vitro, which include promoting the proliferation and differentiation of quail muscle precursor cells. The objective of this study was to investigate overexpression of MSTN-B in vivo by using two independent lines of transgenic Japanese quail with expression directed in the skeletal muscle. Unexpectedly, the chicken skeletal muscle alpha actin 1 (cACTA1) promoter resulted in restricted exogenous MSTN-B protein expression to certain skeletal muscles, such as the gastrocnemius and tibialis anterior, but not the pectoralis major muscle. Gastrocnemius weight as a percentage of body weight in transgenic quail was increased compared to non-transgenic quail at posthatch day 21 (D21) and posthatch D42. An increase in the size of the gastrocnemius in transgenic quail was attributed to an increase in fiber number but not fiber cross-sectional area (CSA). During embryonic development, paired box 7 (PAX7) expression was prolonged in the transgenic embryos, but other myogenic regulatory factors (MRFs) were unchanged after MSTN-B overexpression. Taken together, these data provide novel insights into the regulation of skeletal muscle development by alternative splicing mechanisms in avians.

Sevoflurane Prevents Airway Remodeling via Downregulation of VEGF and TGF-β1 in Mice with OVA-Induced Chronic Airway Inflammation.

Asthma is characterized by chronic airway inflammation, which is the underlying cause of airway remodeling featured by goblet cell hyperplasia, subepithelial fibrosis, and proliferation of smooth muscle. Sevoflurane has been used to treat life-threatening asthma and our previous study shows that sevoflurane inhibits acute lung inflammation in ovalbumin (OVA)-induced allergic mice. However, the effect of sevoflurane on airway remodeling in the context of chronic airway inflammation and the underlying mechanism are still unknown. Here, female C57BL/6 mice were used to establish chronic airway inflammation model. Hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Sirius red (SR) staining were used to evaluate airway remodeling. Protein levels of α-SMA, VEGF, and TGF-β1 in lung tissues were detected by western blotting analyses and immunohistochemistry staining. Results showed that inhalation of sevoflurane inhibited chronic airway inflammation including inflammatory cell infiltration and pro-inflammatory cytokine production in BALF of the OVA-challenged mice. Meanwhile, sevoflurane suppressed airway thickening, goblet cell hyperplasia, smooth muscle hyperplasia, collagen deposition, and fiber hyperplasia in the lung tissues of the mice with airway remodeling. Most notably, sevoflurane inhibited the OVA-induced expressions of VEGF and TGF-β1. These results suggested that sevoflurane effectively inhibits airway remodeling in mouse model of chronic airway inflammation, which may be due to the downregulation of VEGF and TGF-β1in lung tissues. Therefore, our results indicate a potential role of sevoflurane in inhibiting airway remodeling besides its known suppression effect on airway inflammation, and support the use of sevoflurane in treating severe asthma in ICU.

Cloning, SNP detection, and growth correlation analysis of the 5' flanking regions of two myosin heavy chain-7 genes in Mandarin fish (Siniperca chuatsi).

Myosin heavy chains (MYHs) play important roles in muscle growth and contraction. In fish, MYHs contribute to hyperplasia and hypertrophy of muscle fibers, which can continue into adult life and thus result in indeterminate growth in some species. We previously identified two MYH genes, MYH-7a and MYH-7b, that are differentially expressed in Mandarin fish (Siniperca chuatsi) and appear to function in early growth. However, the regulatory role of their 5' flanking regions is unknown. To examine the effects of single nucleotide polymorphisms (SNPs) in these regions, we used genome walking to amplify their flanking sequences and analyzed the regulatory elements and binding sites. A single SNP locus was found in the flanking sequence of each gene. These SNP loci are located in the conserved glucocorticoid receptor binding region (MYH-7a: G-614A; Allele frequency: G:A = 94.9:5.1; GG (89.76) and AG (10.24) genotypes) and the LIM homeobox domain transcription factor binding sequence (MYH-7b: C-1933A; Allele frequency: C:A = 54.8:45.2; AA (20.82), AC (48.81), and CC (30.37) genotypes). At the G-614A loci, the GG genotype exhibited more superior growth traits (total length, body length, body height, etc.) than the AG genotype, with the exception of caudal peduncle length. Alternatively, at the C-1933A loci, the AC and AA genotypes showed significant differences in all growth traits, except for head length, with AC exhibiting superior traits. The AA and CC genotypes showed significant differences in caudal peduncle length and height, while no differences were observed between the AC and CC genotypes. Thus, these SNPs in the 5' flanking regions of MYH-7a and MYH-7b are correlated with superior growth and can be used for selecting Mandarin fish during breeding.