Skeletal Muscle Triacylglycerol Hydrolysis Does Not Influence Metabolic Complications of Obesity

Intramyocellular triacylglycerol (IMTG) accumulation is highly associated with insulin resistance and metabolic complications of obesity (lipotoxicity), whereas comparable IMTG accumulation in endurance-trained athletes is associated with insulin sensitivity (the athlete’s paradox). Despite these findings, it remains unclear whether changes in IMTG accumulation and metabolism per se influence muscle-specific and systemic metabolic homeostasis and insulin responsiveness. By mediating the rate-limiting step in triacylglycerol hydrolysis, adipose triglyceride lipase (ATGL) has been proposed to influence the storage/production of deleterious as well as essential lipid metabolites. However, the physiological relevance of ATGL-mediated triacylglycerol hydrolysis in skeletal muscle remains unknown. To determine the contribution of IMTG hydrolysis to tissue-specific and systemic metabolic phenotypes in the context of obesity, we generated mice with targeted deletion or transgenic overexpression of ATGL exclusively in skeletal muscle. Despite dramatic changes in IMTG content on both chow and high-fat diets, modulation of ATGL-mediated IMTG hydrolysis did not significantly influence systemic energy, lipid, or glucose homeostasis, nor did it influence insulin responsiveness or mitochondrial function. These data argue against a role for altered IMTG accumulation and lipolysis in muscle insulin resistance and metabolic complications of obesity.Obesity is a global public health problem and a major risk factor for insulin resistance and type 2 diabetes. These disorders are characterized by excess lipid accumulation in multiple tissues, primarily as triacylglycerols (TAGs). The lipotoxicity hypothesis suggests that this lipid excess promotes cellular dysfunction and cell death, which ultimately contribute to insulin resistance and metabolic disease (1). However, intracellular TAG accumulation is not always associated with adverse metabolic outcomes, suggesting that TAGs themselves are not pathogenic (2). In contrast, other non-TAG lipid metabolites such as fatty acids (FAs), diacylglycerols (DAGs), and ceramides have been shown to influence glucose homeostasis and insulin action by interfering with insulin signaling and glucose transport, promoting endoplasmic reticulum stress and mitochondrial dysfunction, and activating inflammatory and apoptotic pathways (reviewed in ref. 3). Nevertheless, the precise identities and sources of these bioactive lipid intermediates remain elusive (4,5). Furthermore, whether intracellular TAGs serve as a protective sink or a toxic source of deleterious lipid metabolites that contribute to insulin resistance remains unclear (6).Since skeletal muscle is the major contributor to insulin-mediated glucose disposal, lipid excess in this tissue could have serious implications for systemic glucose homeostasis and insulin responsiveness (7). Indeed, numerous studies have demonstrated a strong association between intramyocellular triacylglycerol (IMTG) accumulation and insulin resistance (reviewed in ref. 8). In contrast, endurance exercise training is characterized by IMTG accumulation and insulin sensitivity (the athlete’s paradox) (2). This variable association between IMTG accumulation and insulin responsiveness has largely been attributed to differences in the balance between lipid delivery and muscle oxidative capacity (8–10). Not surprisingly then, most studies have focused on the impact of muscle FA uptake and/or oxidation on glucose homeostasis and insulin action (11). However, experimental manipulations of these parameters cannot distinguish among the effects of IMTGs, IMTG metabolism, and other lipid intermediates. Furthermore, accumulating evidence suggests that muscle oxidative capacity cannot entirely explain differences in IMTGs or insulin responsiveness (12). These findings have led to speculation that dynamic IMTG metabolism (i.e., TAG synthesis or hydrolysis) may be critically involved in lipid-induced insulin resistance (6). However, few studies have specifically addressed the contribution of IMTG metabolism per se to this process.The regulated storage and release of IMTGs remain poorly understood, but require the coordinated action of synthetic enzymes (i.e., diacylglycerol acyltransferases [DGATs]), hydrolytic enzymes (i.e., adipose triglyceride lipase [ATGL] and hormone sensitive lipase [HSL]), and other lipid droplet proteins (6). Specifically, modulating IMTG synthesis in murine skeletal muscle alters IMTG content and systemic glucose homeostasis, supporting a role for IMTG metabolism in metabolic disease (13–15). However, the metabolic impact of modulating IMTG hydrolysis in vivo remains unclear. Global deletion of either ATGL (16–19) or HSL (20) has produced variable results. The former, but not the latter, results in massive IMTG accumulation with improvement in systemic glucose homeostasis, suggesting that inhibition of ATGL-mediated TAG hydrolysis protects against insulin resistance. In contrast, recent studies in cardiac muscle (21) and other tissues (22,23) indicate that ATGL-mediated TAG hydrolysis is required for mitochondrial function such that enhancing, rather than inhibiting, ATGL action may improve metabolic outcomes. Nevertheless, the autonomous role of skeletal muscle TAG catabolism in influencing muscle-specific and systemic metabolic phenotypes remains unknown.The goal of the current study was to understand the contribution of IMTG hydrolysis to tissue-specific and systemic metabolic phenotypes, particularly glucose homeostasis and insulin action, in the context of obesity. We therefore generated animal models with decreased (skeletal muscle-specific ATGL knockout [SMAKO] mice) and increased (muscle creatine kinase [Ckm]-ATGL transgenic [Tg] mice) ATGL action exclusively in skeletal muscle, and assessed the metabolic consequences at baseline and in response to chronic high-fat feeding. Interestingly, modulation of IMTG hydrolysis via ATGL action did not significantly influence glucose homeostasis, insulin action, or other metabolic phenotypes in the context of obesity despite dramatic changes in IMTG content.     

Role of Splenic Artery Embolization in Management of Traumatic Splenic Injuries: A Prospective Study

The objective of our study was to evaluate the role of splenic artery embolization (SAE) in the management of traumatic splenic injuries. From September 2008 to September 2010, a total of 67 patients underwent nonoperative management (NOM) for blunt splenic injuries. Twenty-two patients were excluded from the study because of associated significant other organ injuries. Twenty-five patients underwent SAE followed by NOM (group A) and 20 patients underwent standard NOM (group B). Improvement in clinical and laboratory parameters during hospital stay were compared between two groups using Chi-square test and Mann–Whitney test. SAE was always technically feasible. The mean length of the total hospital stay was lower in the group A patients (5.4 vs. 6.6 day, [P = 0.050]). There was significant increase in hemoglobin and hematocrit levels and systolic blood pressure (SBP) in group A patients after SAE, whereas in group B patients there was decrease in hemoglobin and hematocrit levels and only slight increase in SBP (pre- and early posttreatment relative change in hemoglobin [P = 0.002], hematocrit [P = 0.001], and SBP [P = 0.017]). Secondary splenectomy rate was lower in group A (4 % [1/25] vs. 15 % [3/20] [P = 0.309]). No procedure-related complications were encountered during the hospital stay and follow-up. Minor complications of pleural effusion, fever, pain, and insignificant splenic infarct noted in 9 (36 %) patients. SAE is a technically feasible, safe, and effective method in the management of splenic injuries. Use of SAE as an adjunct to NOM of splenic injuries results improvement in hemoglobin, hematocrit levels, and SBP. SAE also reduces secondary splenectomy rate and hospital stay.Keyword: Trauma, Splenic artery embolisation     

Peripheral T-cell lymphoma emerging in a patient with aggressive polymyositis: molecular evidence for neoplastic transformation of an oligoclonal T-cell infiltrate

We report a rare case of peripheral T-cell lymphoma arising in a 52-year-old man with biopsy-proven aggressive polymyositis, who had cardiac involvement, progressive bulbar symptoms, and died 11 months post diagnosis due to multiorgan failure. Using a multimodality approach including immunohistochemistry, genome-wide single nucleotide polymorphism (SNP)-array analysis, and high-throughput sequencing of the complementary determining region 3 (CDR3) of T-cell receptor beta (TCRβ) genes, our study demonstrates a molecular link between polymyositis and T-cell lymphoma, and provides evidence of the rapid and possibly late occurrence of genomic instability during neoplastic transformation of an oligoclonal T-cell population. Immunohistochemical analysis revealed loss of CD5, CD7, and CD8 antigen expression in autopsy tissue samples, as well as the occurrence of aberrant CD56 expression, not seen in pre-mortem biopsies, supporting the emergence of a neoplastic T-cell population. Multiplex polymerase chain reaction and next-generation sequencing of the TCRβ CDR3 region displayed two unique T-cell clones in both the diagnostic biopsy confirming polymyositis and the autopsy muscle tissue exhibiting T-cell lymphoma, linking the two pathological processes. SNP-array analysis revealed complex genomic abnormalities at autopsy but not in the pre-mortem muscle biopsies displaying polymyositis, confirming malignant transformation of the oligoclonal T-cell infiltrate. Our findings raise the possibility that clinically aggressive polymyositis might represent a preneoplastic condition in some instances, similar to certain other autoimmune and inflammatory disorders.     

Frontotemporoparietal asymmetry and lack of illness awareness in schizophrenia

Introduction: Lack of illness awareness or anosognosia occurs in both schizophrenia and right hemisphere lesions due to stroke, dementia, and traumatic brain injury. In the latter conditions, anosognosia is thought to arise from unilateral hemispheric dysfunction or interhemispheric disequilibrium, which provides an anatomical model for exploring illness unawareness in other neuropsychiatric disorders, such as schizophrenia. Methods: Both voxel‐based morphometry using Diffeomorphic Anatomical Registration through Exponentiated Lie Algebra (DARTEL) and a deformation‐based morphology analysis of hemispheric asymmetry were performed on 52 treated schizophrenia subjects, exploring the relationship between illness awareness and gray matter volume. Analyses included age, gender, and total intracranial volume as covariates. Results: Hemispheric asymmetry analyses revealed illness unawareness was significantly associated with right < left hemisphere volumes in the anteroinferior temporal lobe (t = 4.83, P = 0.051) using DARTEL, and the dorsolateral prefrontal cortex (t = 5.80, P = 0.003) and parietal lobe (t = 4.3, P = 0.050) using the deformation‐based approach. Trend level associations were identified in the right medial prefrontal cortex (t = 4.49, P = 0.127) using DARTEL. Lack of illness awareness was also strongly associated with reduced total white matter volume (r = 0.401, P < 0.01) and illness severity (r = 0.559, P < 0.01). Conclusion: These results suggest a relationship between anosognosia and hemispheric asymmetry in schizophrenia, supporting previous volume‐based MRI studies in schizophrenia that found a relationship between illness unawareness and reduced right hemisphere gray matter volume. Functional imaging studies are required to examine the neural mechanisms contributing to these structural observations. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Neutral zone approach for the rehabilitation of a severely atrophic mandibular ridge: Case report

Providing a complete denture for a patient with an atrophic mandibular ridge presents a unique challenge for dentists. Retention, stability, and support must be considered when fabricating and fitting a complete denture. This article highlights the use of the neutral zone technique for successful complete denture therapy in a patient with an atrophic mandibular ridge, with special emphasis on the role of coverage of genial tubercles for maximum prosthesis support and stability.     

(E)-2-(2-Allylidenehydrazinyl)thiazole derivatives: Design,green synthesis,in silico and in vitro antimycobacterial and radical scavenging studies

By understanding the rampant infections of Mycobacterium tuberculosis (Mtb) and inflammations caused due to the generation of radical species during the Mtb infection, a series of (E)-2-(2-allylidenehydrazinyl)thiazole derivatives, with dual-action properties, was designed. The molecules were designed with a considerable variation in LogP, one of the critical parameters in physicochemical properties, and analyzed for their drug-likeness. For the synthesis, a simple, green, and multicomponent one-pot synthesis method was developed. The in vitro inhibition potentials were evaluated against Mtb H₃₇Rv by the microplate Alamar Blue assay. The results reveal that compound 6 was potent, with a MIC value of 6.5 µg/ml, and showed better interactions with the KasA protein with binding free energy (ΔG) of −9.4 kcal/mol. Also, the radical scavenging properties were studied to establish the dual-action properties of the molecules. Compound 9 exhibited promising antioxidant and nitric oxide radical scavenging activities, with 81.7% and 81.0%, respectively, at 1,000-μg/ml concentration.