Demonstration Study of Reflector-Based Volumetric Speed-of-Sound Imaging With Linear Ultrasound Arrays.

Conventional B-mode ultrasound imaging has difficulty in delineating homogeneous soft tissues with similar acoustic impedances, as the reflectivity depends on the acoustic impedance at the interface. As a quantitative imaging biomarker sensitive to alteration of biomechanical properties, speed-of-sound (SoS) holds promising potential for tissue and disease differentiation such as delineation of different breast tissue types with similar acoustic impedance. Compared to two-dimensional (2D) SoS images, three-dimensional (3D) volumetric SoS images achieved through a full-angle ultrasound scan can reveal more intricate morphological structures of tissues; however, they generally require a ring transducer. In this study, we introduce a 3D SoS reconstruction system that utilizes hand-held linear arrays instead. This system employs a passive reflector positioned opposite the linear arrays, serving as an echogenic reference for time-of-flight (ToF) measurements, and a high-definition camera to track the location corresponding to each group of transmit-receive data. To merge these two streams of ToF measurements and location tracking, a voxel-based reconstruction algorithm is implemented. Experimental results with gelatin phantom and ex vivo tissue have demonstrated the stability of our proposed method. Moreover, the results underscore the potential of this system as a complementary diagnostic modality, particularly in the context of diseases such as breast cancer.

Mitofusin 2 deficiency leads to oxidative stress that contributes to insulin resistance in rat skeletal muscle cells.

Mitofusin 2 (Mfn2) is a dynamin-like protein anchored in the outer mitochondrial membrane that plays a crucial role in ensuring optimal mitochondrial morphological homeostasis. It has been shown that reduced expression of Mfn2 is associated with insulin resistance, but the mechanism is still unclear. We investigated whether Mfn2 deficiency leads to impaired insulin sensitivity via elevated oxidative stress. L6 skeletal muscle cells were treated with palmitate and Mfn2 expression was repressed by transfection with antisense Mfn2. Levels of antioxidant enzymes, reactive oxygen species (ROS), the phosphorylation of c-Jun N-terminal Kinase (JNK) and nuclear factor-κB (NF-κB) and the mitochondrial membrane potential (Δψm) were measured. The results showed palmitate-induced insulin resistance of skeletal muscle cells was accompanied by Mfn2 repression. Meanwhile, the cells had decreased Δψm and activity of antioxidant enzymes which could increase production of ROS, phosphorylation of JNK and NF-κB. When Mfn2 was up-regulated in palmitate-treated cells, oxidative stress and insulin resistance was alleviated. Furthermore, knock-down of Mfn2 in control cells enhanced oxidative stress. Mfn2 deficiency led to increased superoxide concentration and activation of JNK as well as NF-κB associated with insulin signaling. In conclusion, Mfn2 is a potent repressor for oxidative stress and regulation of Mfn2 expression may prove to be a potential method to circumvent insulin resistance.

Reliable Delineation of Clinical Target Volumes for Cervical Cancer Radiotherapy on CT/MR Dual-Modality Images.

Accurate delineation of the clinical target volume (CTV) is a crucial prerequisite for safe and effective radiotherapy characterized. This study addresses the integration of magnetic resonance (MR) images to aid in target delineation on computed tomography (CT) images. However, obtaining MR images directly can be challenging. Therefore, we employ AI-based image generation techniques to "intelligentially generate" MR images from CT images to improve CTV delineation based on CT images. To generate high-quality MR images, we propose an attention-guided single-loop image generation model. The model can yield higher-quality images by introducing an attention mechanism in feature extraction and enhancing the loss function. Based on the generated MR images, we propose a CTV segmentation model fusing multi-scale features through image fusion and a hollow space pyramid module to enhance segmentation accuracy. The image generation model used in this study improves the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) from 14.87 and 0.58 to 16.72 and 0.67, respectively, and improves the feature distribution distance and learning-perception image similarity from 180.86 and 0.28 to 110.98 and 0.22, achieving higher quality image generation. The proposed segmentation method demonstrates high accuracy, compared with the FCN method, the intersection over union ratio and the Dice coefficient are improved from 0.8360 and 0.8998 to 0.9043 and 0.9473, respectively. Hausdorff distance and mean surface distance decreased from 5.5573 mm and 2.3269 mm to 4.7204 mm and 0.9397 mm, respectively, achieving clinically acceptable segmentation accuracy. Our method might reduce physicians' manual workload and accelerate the diagnosis and treatment process while decreasing inter-observer variability in identifying anatomical structures.

Multi-angle speed-of-sound imaging with sparse sampling to characterize medical tissue properties.

Medical Speed-of-sound (SoS) imaging, which can characterize medical tissue properties better by quantifying their different SoS, is an effective imaging method compared with conventional B-mode ultrasound imaging. As a commonly used diagnostic instrument, a hand-held array probe features convenient and quick inspection. However, artifacts will occur in the single-angle SoS imaging, resulting in indistinguishable tissue boundaries. In order to build a high-quality SoS image, a number of raw data are needed, which will bring difficulties to data storage and processing. Compressed sensing (CS) theory offers theoretical support to the feasibility that a sparse signal can be rebuilt with random but less sampling data. In this study, we proposed an SoS reconstruction method based on CS theory to process signals obtained from a hand-held linear array probe with a passive reflector positioned on the opposite side. The SoS reconstruction method consists of three parts. Firstly, a sparse transform basis is selected appropriately for a sparse representation of the original signal. Then, considering the mathematical principles of SoS imaging, the ray-length matrix is used as a sparse measurement matrix to observe the original signal, which represents the length of the acoustic propagation path. Finally, the orthogonal matching pursuit algorithm is introduced for image reconstruction. The experimental result of the phantom proves that SoS imaging can clearly distinguish tissues that show similar echogenicity in B-mode ultrasound imaging. The simulation and experimental results show that our proposed method holds promising potential for reconstructing precision SoS images with fewer signal samplings, transmission, and storage.

Clinical and genetic characteristics of a child with Sotos syndrome and attention-deficit/hyperactivity disorder: A case report.

BACKGROUND: Sotos syndrome is an autosomal dominant disorder, whereas attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition. This report aimed to summarize the clinical and genetic features of a pediatric case of Soros syndrome and ADHD in a child exhibiting precocious puberty. CASE SUMMARY: The patient presented with accelerated growth and advanced skeletal maturation; however, she lacked any distinct facial characteristics related to specific genetic disorders. Genetic analyses revealed a paternally inherited heterozygous synonymous mutation [c.4605C>T (p.Arg1535Arg)]. Functional analyses suggested that this mutation may disrupt splicing, and bioinformatics analyses predicted that this mutation was likely pathogenic. After an initial diagnosis of Sotos syndrome, the patient was diagnosed with ADHD during the follow-up period at the age of 8 years and 7 months. CONCLUSION: The potential for comorbid ADHD in Sotos syndrome patients should be considered to avoid the risk of a missed diagnosis.

Mitofusion-2-mediated alleviation of insulin resistance in rats through reduction in lipid intermediate accumulation in skeletal muscle.

BACKGROUND: Increased lipid accumulation and mitochondrial dysfunction within skeletal muscle have been shown to be strongly associated with insulin resistance. However, the role of mitofusion-2 (MFN2), a key factor in mitochondrial function and energy metabolism, in skeletal muscle lipid intermediate accumulation remains to be elucidated. RESULTS: A high-fat diet resulted in insulin resistance as well as accumulation of cytosolic lipid intermediates and down-regulation of MFN2 and CPT1 in skeletal muscle in rats, while MFN2 overexpression improved insulin sensitivity and reduced lipid intermediates in muscle, possibly by upregulation of CPT1 expression. CONCLUSIONS: MFN2 overexpression can rescue insulin resistance, possibly by upregulating CPT1 expression leading to reduction in the accumulation of lipid intermediates in skeletal muscle. These observations contribute to the investigations of new diabetes therapies.

Phosphorylated proteomics-based analysis of the effects of semaglutide on hippocampi of high-fat diet-induced-obese mice.

The aim of this paper was to investigate the effects of semaglutide on phosphorylated protein expression, and its neuroprotective mechanism in hippocampi of high-fat-diet-induced obese mice. In total, 16 obese mice were randomly divided into model group (H group) and semaglutide group (S group), with 8 mice in each group. In addition, a control group (C group) was set up comprising 8 C57BL/6J male normal mice. The Morris water maze assay was conducted to detect cognitive function changes in the mice, and to observe and compare body weight and expression levels of serological indicators between groups after the intervention. Phosphorylated proteomic analysis was performed to detect the hippocampal protein profile in mice. Proteins up-regulated twofold or down-regulated 0.5-fold in each group and with t-test p < 0.05 were defined as differentially phosphorylated proteins and were analyzed bioinformatically. The results showed that the high-fat diet-induced obese mice had reduced body weight, improved oxidative stress indexes, significantly increased the percentage of water maze trips and the number of platform crossings, and significantly shortened the water maze platform latency after semaglutide intervention. The phosphorylated proteomics results identified that 44 overlapping proteins among the three experimental groups. Most of the phosphorylated proteins identified were closely associated with pathways of neurodegeneration-multiple diseases. In addition, we identified Huntington, Neurofilament light chain, Neurofilament heavy chain as drug targets. This study demonstrates for the first time that semaglutide exerts neuroprotective effects by reducing HTT Ser1843, NEFH Ser 661 phosphorylation and increasing NEFL Ser 473 phosphorylation in hippocampal tissue of obese mice.

Bone marrow sparing oriented multi-model image registration in cervical cancer radiotherapy.

Cervical cancer poses a serious threat to the health of women and radiotherapy is one of the primary treatment methods for this condition. However, this treatment is associated with a high risk of causing acute hematologic toxicity. Delineating the bone marrow (BM) for sparing based on computer tomography (CT) images before radiotherapy can effectively avoid this risk. Unfortunately, compared to magnetic resonance (MR) images, CT images lack the ability to express the activity of BM. Therefore, medical practitioners currently manually delineate the BM on CT images by corresponding to MR images. However, the manual delineation of BM is time-consuming and cannot guarantee accuracy due to the inconsistency of the CT-MR multimodal images. This study proposes a multimodal image-oriented automatic registration method for pelvic BM sparing. The proposed method includes three-dimensional (3D) bone point clouds reconstruction and an iterative closest point registration based on a local spherical system for marking BM on CT images. By introducing a joint coordinate system that combines the global Cartesian coordinate system with the local point clouds' spherical coordinate system, the increasement of point descriptive dimension avoids the local optimal registration and improves the registration accuracy. Experiments on the dataset of patients demonstrate that our proposed method can enhance the multimodal image registration accuracy and efficiency for medical practitioners in BM-sparing of cervical cancer radiotherapy. The method proposed in this contribution might also provide a solution to multimodal registration, especially in multimodal sequential images in other clinical applications, such as the diagnosis of cervical cancer and the preservation of normal organs during radiotherapy.

Gestational Weight Gain and Small for Gestational Age in Obese Women: A Systematic Review and Meta-Analysis.

Objective: This systematic review and meta-analysis evaluates the relationship between gestational weight gain and the risk of small for gestational age in obese pregnant women. Methods: Studies were identified by searching the Web of Science, Embase, and PubMed databases up to June 30th, 2022. The meta-analysis was carried out to determine the risk of small for gestational age with gestational weight gain (GWG) below the 2009 Institute of Medicine (IOM) guidelines compared with within the guidelines in obese women. The Newcastle-Ottawa Scale was used to assess the methodological quality. The chi-squared test, Q test, and I2 test were used to evaluate statistical heterogeneity. Subgroup analyses were conducted, and publication bias was assessed by funnel plots and Egger's test. Sensitivity analyses were performed for three groups of obese people (I: BMI 30-34.9 kg/m2, II: BMI 35-39.9 kg/m2, and III: BMI ≥ 40 kg/m2) to examine the association of obesity and SGA. Results: A total of 788 references were screened, and 29 studies (n = 1242420 obese women) were included in the systematic review. Obese women who gained weight below the IOM guideline had a higher risk of SGA than those who gained weight within the guideline (OR = 1.27, 95% CI = 1.16-1.38, Z = 5.36). Both weight loss (<0 kg) and inadequate weight (0-4.9 kg) during pregnancy in obese women are associated with an increased risk of SGA (OR = 1.50, 95% CI = 1.37-1.64, Z = 8.82) (OR = 1.18, 95% CI = 1.14-1.23, Z = 8.06). The same conclusions were also confirmed for the three obesity classes (I: OR = 1.38, 95% CI = 1.29-1.47; II: OR = 1.39, 95% CI = 1.30-1.49; and III: OR = 1.26, 95% CI = 1.16-1.37). Subgroup analysis by country showed that GWG below guidelines in obese women of the USA and Europe was associated with risk for SGA (USA (OR = 1.30, 95% CI = 1.15-1.46), Europe (OR = 1.24, 95% CI = 1.11-1.40)) and not in Asia (OR = 1.17, 95% CI = 0.91-1.50). Conclusion: Our findings indicated that obese pregnant women who had weight loss or inadequate weight (0-4.9 kg) according to the IOM guideline had increased risks for SGA. Moreover, we also evaluated that gestational weight loss (<0 kg) in these pregnancies was associated with an increased risk for SGA compared with inadequate weight (0-4.9 kg) in these pregnancies. Therefore, the clinical focus should assist obese women to achieve GWG within the IOM guidelines to decrease the risk for SGA.

Association Between Serum Vitamin D Levels and Ketosis Episodes in Hospitalized Patients with Newly Diagnosed Ketosis-Prone Type 2 Diabetes.

Purpose: This study aimed to investigate the relationship between 25-hydroxyvitamin D (25OHD) and the onset of ketosis in newly diagnosed patients with ketosis-prone type 2 diabetes (KPT2D). Patients and Methods: A total of 162 patients with non-autoimmune newly diagnosed diabetes mellitus were included in this cross-sectional study. Patients were classified into KPT2D (n = 71) or non-ketotic type 2 diabetes (NKT2D, n = 91). Anthropometric parameters, islet functions, biochemical parameters, and body composition were determined in both KPT2D and NKT2D groups. Correlation analysis was performed to determine the associations between 25OHD and plasma ketones. The risk factors associated with ketosis episodes in patients with new-onset KPT2D were evaluated using binary logistic regression analysis. Results: Vitamin D deficiency was observed in both patients with KPT2D and NKT2D. Compared with the NKT2D group, serum 25OHD values were lower in the participants of the KPT2D group [14.20 (10.68, 19.52) vs 16.98 (13.54,2.96) ng/mL, P = 0.011]. Serum 25OHD was associated with plasma ketones (R = -0.387). Serum 25OHD is an independent protective factor for ketosis or ketoacidosis episodes in patients with new onset of KPT2D (P = 0.037, OR = 0.921). Conclusion: Vitamin D levels are associated with ketosis episodes in patients with KPT2D. Serum 25OHD is an independent protective factor for ketosis episodes in patients with KPT2D.

Single Nucleotide Polymorphism Detection for Peach Gummosis Disease Resistance by Genome-Wide Association Study.

Peach gummosis is one of the most widespread and destructive diseases. It causes growth stunting, yield loss, branch, trunk, and tree death, and is becoming a restrictive factor in healthy and sustainable development of peach production. Although a locus has been identified based on bi-parental quantitative trait locus (QTL) mapping, selection of gummosis-resistant cultivars remains challenging due to the lack of resistant parents and of the complexity of an inducing factor. In this study, an integrated approach of genome-wide association study (GWAS) and comparative transcriptome was used to elucidate the genetic architecture associated with the disease using 195 accessions and 145,456 genome-wide single nucleotide polymorphisms (SNPs). The broad-sense and narrow-sense heritabilities were estimated using 2-year phenotypic data and genotypic data, which gave high values of 70 and 73%, respectively. Evaluation of population structure by neighbor-joining and principal components analysis (PCA) clustered all accessions into three major groups and six subgroups, mainly according to fruit shape, hairy vs. glabrous fruit skin, pedigree, geographic origin, and domestication history. Five SNPs were found to be significantly associated with gummosis disease resistance, of which SNPrs285957, located on chromosome6 across 28 Mb, was detected by both the BLINK and the FarmCPU model. Six candidate genes flanked by or harboring the significant SNPs, previously implicated in biotic stress tolerance, were significantly associated with this resistance. Two highly resistant accessions were identified with low disease severity, which could be potential sources of resistance genes for breeding. Our results provide a fresh insight into the genetic control of peach gummosis disease.

Peach allergen Pru p 1 content is generally low in fruit but with large variation in different varieties.

BACKGROUND: Pru p 1 is a major allergen in peach and nectarine, and the different content in varieties may affect the degree of allergic reactions. This study aimed to quantify Pru p 1 levels in representative peach varieties and select hypoallergenic Pru p 1 varieties. METHODS: To obtain monoclonal and polyclonal antibodies, mice and rabbits, respectively, were immunized with recombinant Pru p 1.01 and Pru p 1.02. The Pru p 1 levels in fruits from 83 representative peach varieties was quantified by sandwich enzyme-linked immunosorbent assay (sELISA). nPru p 1 was obtained through specific monoclonal antibody affinity purification and confirmed by Western blot and mass spectrometry. The variable Pru p 1 content of selected varieties was evaluated by Western blot and the expression level of encoding Pru p 1 genes by quantitative polymerase chain reaction. RESULTS: A sELISA method with monoclonal and polyclonal antibodies was built for quantifying Pru p 1 levels in peach. Pru p 1 was mainly concentrated in the peel (0.20-73.44 µg/g, fresh weight), being very low in the pulp (0.05-9.62 µg/g) and not detected in wild peach. For the 78 peach and nectarine varieties, Pru p 1 content varied widely from 0.12 to 6.45 µg/g in whole fruit. We verified that natural Pru p 1 is composed of 1.01 and 1.02 isoallergens, and the Pru p 1 expression level and Pru p 1 band intensity in the immunoblots were in agreement with protein quantity determined by ELISA for some tested varieties. In some cases, the reduced levels of Pru p 1 did not coincide with low Pru p 3 in the same variety in whole fruit, while some ancient wild peach and nectarines contained low levels of both allergens, and late-ripening yellow flesh varieties were usually highly allergenic. CONCLUSION: Pru p 1 content is generally low in peach compared to Pru p 3. Several hypoallergenic Pru p 1 and Pru p 3 varieties, "Zi Xue Tao," "Wu Yue Xian," and "May Fire," were identified, which could be useful in trials for peach allergy patients.

High Body Mass Index and Triglycerides Help Protect against Osteoporosis in Patients with Type 2 Diabetes Mellitus.

PURPOSE: This study was conducted to investigate whether high body mass index (BMI) and triglycerides (TGs) were protective factors for reducing osteoporosis (OP) in patients with type 2 diabetes mellitus (T2DM). Participants and Methods. Seventy-nine patients (aged 20 to 81) with T2DM were included in the study. Basic information and blood indicators were collected. Bone mineral density was used to diagnose OP. Participants were grouped according to BMI (normal weight vs. overweight/obese participants), TG (normal TG vs. hypertriglyceridemia), and OP (non-OP vs. OP), and differences were compared between groups. Regression analysis was used to explore whether BMI or TG were independent factors affecting OP. RESULTS: The proportions of OP in the overweight/obese and hypertriglyceridemic groups were significantly lower than those in the normal weight (30.0% vs. 69.0%; P = 0.001) and normal TG (27.3% vs. 56.5%; P = 0.010) groups. In the OP group, the BMI (24.8 ± 3.4 vs. 26.6 ± 2.5 kg/m2; P = 0.009) was significantly lower than that in the non-OP group, and TG showed the same trend (1.30 (0.81) vs. 1.71 (1.1) mmol/L; P = 0.020). Logistic regression in the crude model showed that the odds ratios (ORs) of OP in the overweight/obese and hypertriglyceridemic groups were 0.193 (95% CI: 0.071, 0.520) and 0.315 (95% CI: 0.119, 0.830) compared with those of the normal weight and normal TG groups. After adjusting for sex and smoking, the ORs were 0.204 (95% CI: 0.074, 0.567) and 0.242 (95% CI: 0.082, 0.709) for the overweight/obese and hypertriglyceridemic groups, respectively. After adjusting for all confounding factors, the ORs for these groups were 0.248 (95% CI: 0.083, 0.746) and 0.299 (95% CI: 0.091, 0.989), respectively. CONCLUSION: BMI and TG are independent protective factors against OP in patients with T2DM.

Effects of Glycated Hemoglobin Level on Bone Metabolism Biomarkers in Patients with Type 2 Diabetes Mellitus.

PURPOSE: We aimed to determine the relationship between the levels of glycated hemoglobin (HbA1c) and biomarkers of bone metabolism in patients with type 2 diabetes mellitus (T2DM), and whether HbA1c independently influences any of these biomarkers. PATIENTS AND METHODS: A cohort study of 240 patients with T2DM was performed. Serum was obtained and used to measure HbA1c, total cholesterol (TC), triglycerides, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol (LDL-C), very-low-density lipoprotein-cholesterol, apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB), total protein, albumin, blood urea nitrogen (BUN), creatinine, serum 25-hydroxyvitamin D (25OHD), osteocalcin (OC), ß-C-terminal cross-linked telopeptide of type I collagen (ß-CTX), procollagen type 1 N-terminal propeptide (P1NP), or parathyroid hormone (PTH) concentrations. The participants were divided into three study groups according to HbA1c level: <7%, 7-9% and ≥9%. Chi-square testing and one-way analysis of variance were used to compare groups. The relationships between HbA1c and bone metabolism biomarker values were analyzed using linear correlation analysis and multiple linear regression analysis. RESULTS: Age, duration of T2DM, and the concentrations of TC, LDL-C, apolipoprotein B, albumin, and BUN showed significant difference among the <7%, 7-9% and ≥9% HbA1c groups. Of the bone metabolism biomarkers, there were significant differences in serum 25-hydroxyvitamin D (25OHD) and osteocalcin (OC) among the groups. The correlation coefficients (r) for the relationships of HbA1c with 25OHD and OC were -0.200 and -0.183, respectively (P <0.05). Regardless of adjustment for none, some, or all of the confounding factors (age, sex, and duration of T2DM), the 25OHD and OC concentrations were significantly lower in the HbA1c ≥9% group than in the HbA1c <7% group. HbA1c showed no relationship with ß-CTX, PINP, or PTH. CONCLUSION: T2DM patients with poorer glycemic control had lower concentrations of serum 25OHD and OC, suggesting that HbA1c is an independent risk factor for low 25OHD and OC.

VEGF gene transfected umbilical cord mesenchymal stem cells transplantation improve the lower limb vascular lesions of diabetic rats.

BACKGROUND: Previous studies had explored the therapeutic effect of hUC-MSCs transplantation on ischemia; in this study, we further assessed the effectiveness of VEGF over-expressed hUC-MSCs cells transplantation on vascular proliferation in lower limb ischemia model in type 2 diabetic rats. METHODS: hUC-MSCs cells were over-expressed with VEGF, and transplanted to lower limb ischemia rats model of type 2 diabetes. RESULTS: VEGF over-expression increased the hUC-MSCs cells proliferation activity and VEGF secretion. VEGF gene transfected hUC-MSCs transplantation increased VEGF expression at a high level throughout 4weeks in skeletal muscle tissues of rats. Importantly, the vascular proliferation and blood perfusion of VEGF over-expressed hUC-MSCs transplanted limb were significantly improved compared with those of control group. The expression levels of ERK, AKT, MMP2 and MMP9 in VEGF over-expressed hUC-MSCs transplantation group increased dramatically compared with control group, while TIMP1 and TIMP2 expression had no significant change. CONCLUSION: VEGF over-expressed hUC-MSCs transplantation was more effective to stimulate angiogenesis and increase blood perfusion than the simply hUC-MSCs transplantation, as maybe a new choice to improve the lower limb vascular lesions of diabetics.

Mitofusin-2 ameliorates high-fat diet-induced insulin resistance in liver of rats.

AIM: To investigate the effects of mitofusin-2 (MFN2) on insulin sensitivity and its potential targets in the liver of rats fed with a high-fat diet (HFD). METHODS: Rats were fed with a control or HFD for 4 or 8 wk, and were then infected with a control or an MFN2 expressing adenovirus once a week for 3 wk starting from the 9(th) wk. Blood glucose (BG), plasma insulin and insulin sensitivity of rats were determined at end of the 4(th) and 8(th) wk, and after treatment with different amounts of MFN2 expressing adenovirus (10(8), 10(9) or 10(10) vp/kg body weight). BG levels were measured by Accu-chek Active Meter. Plasma insulin levels were analyzed by using a Rat insulin enzyme-linked immunosorbent assay kit. Insulin resistance was evaluated by measuring the glucose infusion rate (GIR) using a hyperinsulinemic euglycemic clamp technique. The expression or phosphorylation levels of MFN2 and essential molecules in the insulin signaling pathway, such as insulin receptor (INSR), insulin receptor substrate 2 (IRS2), phosphoinositide-3-kinase (PI3K), protein kinase beta (AKT2) and glucose transporter type 2 (GLUT2) was assayed by quantitative real-time polymerase chain reaction and Western-blotting. RESULTS: After the end of 8 wk, the body weight of rats receiving the normal control diet (ND) and the HFD was not significantly different (P > 0.05). Compared with the ND group, GIR in the HFD group was significantly decreased (P < 0.01), while the levels of BG, triglycerides (TG), total cholesterol (TC) and insulin in the HFD group were significantly higher than those in the ND group (P < 0.05). Expression of MFN2 mRNA and protein in liver of rats was significantly down-regulated in the HFD group (P < 0.01) after 8 wk of HFD feeding. The expression of INSR, IRS2 and GLUT2 were down-regulated markedly (P < 0.01). Although there were no changes in PI3K-P85 and AKT2 expression, their phosphorylation levels were decreased significantly (P < 0.01). After intervention with MFN2 expressing adenovirus for 3 wk, the expression of MFN2 mRNA and protein levels were up-regulated (P < 0.01). There was no difference in body weight of rats between the groups. The levels of BG, TG, TC and insulin in rats were lower than those in the Ad group (P < 0.05), but GIR in rats infected with Ad-MFN2 was significantly increased (P < 0.01), compared with the Ad group. The expression of INSR, IRS2 and GLUT2 was increased, while phosphorylation levels of PI3K-P85 and AKT2 were increased (P < 0.01), compared with the Ad group. CONCLUSION: HFDs induce insulin resistance, and this can be reversed by MFN2 over-expression targeting the insulin signaling pathway.

Overexpression of mitofusin 2 improves translocation of glucose transporter 4 in skeletal muscle of high­fat diet­fed rats through AMP­activated protein kinase signaling.

Mitofusin 2 (Mfn2) is a mitochondrial membrane protein that plays a role in mitochondrial fusion and metabolism in mammalian cells. Previous studies have reported a positive correlation between Mfn2 expression and insulin sensitivity in non­diabetic and type 2 diabetic subjects. Thus, the aim of the present study was to investigate whether Mfn2 overexpression improves insulin sensitivity of high­fat diet (HFD) rats and the possible underlying mechanisms. Male SD rats were randomly divided into four groups: negative control; HFD; HFD plus adenoviral vectors; and HFD plus adenoviral vectors encoding Mfn2. Following an 11­week treatment protocol, the euglycemic­hyperinsulinemic clamp technique was applied to evaluate insulin sensitivity in rats. The skeletal muscles from rats in each group were analyzed by real­time PCR and western blot analysis to determine glucose transporter 4 (GLUT4) expression, translocation and relative translocation signaling. Consistent with Mfn2 repression and glucose intolerance, HFD downregulates GLUT4 expression at the mRNA and protein levels, while Mfn2 overexpression activates AMP­activated protein kinase (AMPK), increases GLUT4 expression and translocation and improves insulin resistance in the skeletal muscles of HFD rats. Results of the present study indicate that Mfn2 overexpression improves insulin sensitivity and may regulate GLUT4 translocation in an AMPK­dependent manner in the skeletal muscles of HFD rats. This study is likely to provide insight into the unique role of Mfn2 in promoting glucose uptake, leading to modulation of GLUT4 translocation signaling and maintenance of glucose homeostasis in vivo.