Mohs Micrographic Surgery for Facial Merkel Cell Carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare malignant cutaneous tumor with frequent metastases. They often appear in the face where cosmetic and functional outcome is critical. Mohs micrographic surgery (MMS) is a controlled intervention that optimizes negative margins without sacrificing tissue. OBJECTIVE: A comprehensive assessment of outcomes of MMS-treated facial MCC will help guide clinicians in surgical and medical management. METHODS & MATERIALS: Retrospective review identified facial MCC cases treated with MMS at a single institution from January 2005 to August 2020. Tumor characteristics and outcomes were recorded and descriptive and predictive analyses were performed. RESULTS: 34 cases were reviewed with a mean followup of 34.4 months. The most common sites were the forehead, cheek-jaw region, and nasal ala. 2 (5.9%) patients had local recurrence by a mean of 4.3 months. No documented variables were significantly associated with local recurrence. 8 (23.5%) patients had progression to metastasis by a mean of 9.4 months. Younger age at biopsy and surgery, male sex, and intraoperative detection of in-transit disease were significantly associated with progression to metastasis. CONCLUSIONS: In summary, the tissue-sparing approach of MMS may be beneficial for MCC in cosmetically and functionally sensitive facial locations as it preserves tissue without compromising outcomes.

Video coding deep learning-based modeling for long life video streaming over next network generation.

Availability is one of the primary goals of smart networks, especially, if the network is under heavy video streaming traffic. In this paper, we propose a deep learning based methodology to enhance availability of video streaming systems by developing a prediction model for video streaming quality, required power consumption, and required bandwidth based on video codec parameters. The H.264/AVC codec, which is one of the most popular codecs used in video steaming and conferencing communications, is chosen as a case study in this paper. We model the predicted consumed power, the predicted perceived video quality, and the predicted required bandwidth for the video codec based on video resolution and quantization parameters. We train, validate, and test the developed models through extensive experiments using several video contents. Results show that an accurate model can be built for the needed purpose and the video streaming quality, required power consumption, and required bandwidth can be predicted accurately which can be utilized to enhance network availability in a cooperative environment.

Dactylospongia elegans-A Promising Drug Source: Metabolites, Bioactivities, Biosynthesis, Synthesis, and Structural-Activity Relationship.

Marine environment has been identified as a huge reservoir of novel biometabolites that are beneficial for medical treatments, as well as improving human health and well-being. Sponges have been highlighted as one of the most interesting phyla as new metabolites producers. Dactylospongia elegans Thiele (Thorectidae) is a wealth pool of various classes of sesquiterpenes, including hydroquinones, quinones, and tetronic acid derivatives. These metabolites possessed a wide array of potent bioactivities such as antitumor, cytotoxicity, antibacterial, and anti-inflammatory. In the current work, the reported metabolites from D. elegans have been reviewed, including their bioactivities, biosynthesis, and synthesis, as well as the structural-activity relationship studies. Reviewing the reported studies revealed that these metabolites could contribute to new drug discovery, however, further mechanistic and in vivo studies of these metabolites are needed.

HPLC with Fluorescence and Photodiode Array Detection for Quantifying Capmatinib in Biological Samples: Application to In Vivo and In Vitro Studies.

Capmatinib, a recently approved tyrosine kinase inhibitor, is used for the treatment of non-small cell lung cancer. We describe two new HPLC methods for capmatinib quantification in vivo and in vitro. HPLC with a fluorescence detection method was used to quantify capmatinib in plasma for the first time. The method was successfully applied in a pharmacokinetic study following a 10 mg/kg oral dose of capmatinib given to rats. The chromatographic separation was performed using a Eurospher II 100-3 C18H (50 × 4 mm, 3 µm) column and a mobile phase containing 10 mM of ammonium acetate buffer (pH 5.5): acetonitrile (70:30, v/v), at a flow rate of 2.0 mL min-1. The study also describes the use of HPLC-PDA for the first time for the determination of capmatinib in human liver microsomes and describes its application to study its metabolic stability in vitro. Our results were in agreement with those reported using LC-MS/MS, demonstrating the reliability of the method. The study utilized a Gemini-NX C18 column and a mobile phase containing methanol: 20 mM ammonium formate buffer pH 3.5 (53:47, v/v), delivered at a flow rate of 1.1 mL min-1. These methods are suitable for supporting pharmacokinetic studies, particularly in bioanalytical labs lacking LC-MS/MS capabilities.

Genus Smenospongia: Untapped Treasure of Biometabolites-Biosynthesis, Synthesis, and Bioactivities.

Marine sponges continue to attract remarkable attention as one of the richest pools of bioactive metabolites in the marine environment. The genus Smenospongia (order Dictyoceratida, family Thorectidae) sponges can produce diverse classes of metabolites with unique and unusual chemical skeletons, including terpenoids (sesqui-, di-, and sesterterpenoids), indole alkaloids, aplysinopsins, bisspiroimidazolidinones, chromenes, γ-pyrones, phenyl alkenes, naphthoquinones, and polyketides that possessed diversified bioactivities. This review provided an overview of the reported metabolites from Smenospongia sponges, including their biosynthesis, synthesis, and bioactivities in the period from 1980 to June 2022. The structural characteristics and diverse bioactivities of these metabolites could attract a great deal of attention from natural-product chemists and pharmaceuticals seeking to develop these metabolites into medicine for the treatment and prevention of certain health concerns.

In Vitro Anti-Inflammatory Activity of Cotula anthemoides Essential Oil and In Silico Molecular Docking of Its Bioactives.

The genus Cotula (Asteraceae) comprises about 80 species, amongst them Cotula anthemoides L. It is a wild plant growing in Egypt that possesses many traditional uses as a headache, colic, and chest cold remedy. In our study, the chemical composition of C. anthemoides essential oils was analyzed using GC-MS spectroscopy. Sixteen components of leave and stem oils and thirteen components of flower oils were characterized. The main components in both essential oil parts were camphor (88.79% and 86.45%) and trans-thujone (5.14% and 10.40%) in the leaves and stems and the flowers, respectively. The anti-inflammatory activity of the oils in lipopolysaccharide-stimulated RAW 264.7 macrophage cells was evaluated. The flower oil showed its predominant effect in the amelioration of proinflammatory cytokines and tumor necrosis factor-α, as well as cyclooxygenase-2. The bornyl acetate showed the highest affinity for the cyclooxygenase-2 receptor, while compound cis-p-menth-2-ene-1-ol had the best affinity for the tumor necrosis factor receptor, according to the results of molecular docking. In addition, the molecule cis-ß-farnesene showed promising dual affinity for both studied receptors. Our findings show that essential oils from C. anthemoides have anti-inflammatory properties through their control over the generation of inflammatory mediators. These findings suggest that C. anthemoides essential oils could lead to the discovery of novel sources of anti-inflammatory treatments.

Physiologically-based pharmacokinetic model for alectinib, ruxolitinib, and panobinostat in the presence of cancer, renal impairment, and hepatic impairment.

Renal (RIP) and hepatic (HIP) impairments are prevalent conditions in cancer patients. They can cause changes in gastric emptying time, albumin levels, hematocrit, glomerular filtration rate, hepatic functional volume, blood flow rates, and metabolic activity that can modify drug pharmacokinetics. Performing clinical studies in such populations has ethical and practical issues. Using predictive physiologically-based pharmacokinetic (PBPK) models in the evaluation of the PK of alectinib, ruxolitinib, and panobinostat exposures in the presence of cancer, RIP, and HIP can help in using optimal doses with lower toxicity in these populations. Verified PBPK models were customized under scrutiny to account for the pathophysiological changes induced in these diseases. The PBPK model-predicted plasma exposures in patients with different health conditions within average 2-fold error. The PBPK model predicted an area under the curve ratio (AUCR) of 1, and 1.8, for ruxolitinib and panobinostat, respectively, in the presence of severe RIP. On the other hand, the severe HIP was associated with AUCR of 1.4, 2.9, and 1.8 for alectinib, ruxolitinib, and panobinostat, respectively, in agreement with the observed AUCR. Moreover, the PBPK model predicted that alectinib therapeutic cerebrospinal fluid levels are achieved in patients with non-small cell lung cancer, moderate HIP, and severe HIP at 1-, 1.5-, and 1.8-fold that of healthy subjects. The customized PBPK models showed promising ethical alternatives for simulating clinical studies in patients with cancer, RIP, and HIP. More work is needed to quantify other pathophysiological changes induced by simultaneous affliction by cancer and RIP or HIP.

Why do students skip classroom lectures: A single dental school report.

BACKGROUND: Conventional classroom lectures continue to represent a major component of the dental education system to ensure optimum delivery of knowledge. Certain number of students are less compliant and likely to skip classes which may impact the overall academic performance. The aim of this study was to investigate dental students' attitude towards classroom attendance and potential reasons for absenteeism at King Abdulaziz University-Faculty of Dentistry (KAU-FD). METHODS: This was a cross-sectional survey of all dental students actively enrolled at KAU-FD from January to June 2019. The survey included questions on demographics, average travel time to school, current dental year, most recent GPA, student's perspective toward classroom lectures. The survey was validated and distributed to all students at a pre-selected time frame. Data were analysed and presented as frequencies and percentages; chi-square test was used to explore parameters association. RESULTS: A total of 678 students consented and completed the survey. Overall, 44.3% of students were more likely to skip two classes or less per month. Second year dental students were more likely to be absent from classroom lectures (31.3%), while 3rd year dental students were less likely to do so (15.4%). Reported students' justifications for missing classes included early morning classes (47.9%), exams preparation (42%), and lecturer's weak presentation skills (41.9%). CONCLUSION: Compliance of dental students with classroom attendance has been an ongoing challenge for most programs. The current data suggests a multifactorial module for students' attitude toward classroom attendance. Future studies focusing on reasons behind classroom attendance behavior and addressing students' concerns are needed.

A chloride channel in rat pancreatic acinar AR42J cells is sensitive to extracellular acidification and dependent on ROS.

Extracellular acidification, playing a promoting role in the process of acute pancreatitis, has been reported to activate Cl- channels in several types of cells. However, whether extracellular acidification aggravates acute pancreatitis via activating Cl- channels remains unclear. Here, we investigated the effects of extracellular acidification on Cl- channels in rat pancreatic acinar AR42J cells using whole-cell patch-clamp recordings. We found that extracellular acidification induced a moderately outward-rectified Cl- current, with a selectivity sequence of I- > Br- ≥ Cl- > gluconate-, while intracellular acidification failed to induce the currents. The acid-sensitive currents were inhibited by Cl- channel blockers, 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt hydrate and 5-Nitro-2-(3-phenylpropylamino) benzoic acid. After ClC-3 was silenced by ClC-3 shRNA, the acid-sensitive Cl- currents were attenuated significantly, indicating that ClC-3 plays a vital role in the induction of acid-sensitive Cl- currents. Extracellular acid elevated the intracellular level of reactive oxygen species (ROS) significantly, prior to inducing Cl- currents. When ROS production was scavenged, the acid-sensitive Cl- currents were abolished. Whereas, the level of acid-induced ROS was unaffected with silence of ClC-3. Our findings above demonstrate that extracellular acidification induces a Cl- current in pancreatic acinar cells via promoting ROS generation, implying an underlying mechanism that extracellular acidification might aggravate acute pancreatitis through Cl- channels.

Genetic basis of neurodevelopmental disorders in 103 Jordanian families.

We recruited 103 families from Jordan with neurodevelopmental disorders (NDD) and patterns of inheritance mostly suggestive of autosomal recessive inheritance. In each family, we investigated at least one affected individual using exome sequencing and an in-house diagnostic variant interpretation pipeline including a search for copy number variation. This approach led us to identify the likely molecular defect in established disease genes in 37 families. We could identify 25 pathogenic nonsense and 11 missense variants as well as 3 pathogenic copy number variants and 1 repeat expansion. Notably, 11 of the disease-causal variants occurred de novo. In addition, we prioritized a homozygous frameshift variant in PUS3 in two sisters with intellectual disability. To our knowledge, PUS3 has been postulated only recently as a candidate disease gene for intellectual disability in a single family with three affected siblings. Our findings provide additional evidence to establish loss of PUS3 function as a cause of intellectual disability.

Comparison of adhesin genes expression among Klebsiella oxytoca ESBL-non-producers in planktonic and biofilm mode of growth, and imipenem sublethal exposure.

BACKGROUND: Bacterial adhesins play an important role in the bacterial attachment and colonization. The aim of this study was comparison of adhesin genes expression in the planktonic and biofilm mode of growth among ESBL-non-producers isolates of K. oxytoca and effect of imipenem. MATERIALS AND METHODS: A total of eight extended-spectrum beta-lactamase (ESBL) non-producer K. oxytoca isolates were included from patients with hemorrhagic colitis. The adhesin genes including fimA (type 1 fimbria), mrkA (type 3 fimbria), pilQ and the capsular matB genes were adopted. Phenotypic biofilm production was assessed by microtiter tissue plate assay. Expression of adhesin genes in the planktonic and biofilm growth conditions was calculated using quantitative Real-time PCR (RT-qPCR) technique and sub-MIC (0.25 µg/ml) levels of imipenem were also added to broth culture of isolates to evaluate the gene expression. RESULTS: The isolates produced biofilm in moderate level. The expression of pilQ, mrkA and matB but not fimA genes was significantly higher in biofilm conditions compared to the planktonic mode of growth (p = 0.002, p = 0.011 and p = 001, respectively). In addition, imipenem sub-MIC treatment led to a significant overexpression of matB (p = 0.002) and mrkA (p = 0.003) genes compared to the control group. CONCLUSION: Although none of isolates produced strong biofilm, biofilm conditions led to the increase in the expression of adhesin encoding genes in non-ESBL-producing K. oxytoca. Furthermore, ß-lactams; and especially carbapenems possibly increase the colonization of K. oxytoca and increase the biofilm formation. Hence, accurate consumption of antibiotics must be considered.

The structure-energy landscape of NMDA receptor gating.

N-Methyl-D-aspartate (NMDA) receptors are the main calcium-permeable excitatory receptors in the mammalian central nervous system. The NMDA receptor gating is complex, exhibiting multiple closed, open, and desensitized states; however, central questions regarding the conformations and energetics of the transmembrane domains as they relate to the gating states are still unanswered. Here, using single-molecule Förster resonance energy transfer (smFRET), we map the energy landscape of the first transmembrane segment of the Rattus norvegicus NMDA receptor under resting and various liganded conditions. These results show kinetically and structurally distinct changes associated with apo, agonist-bound, and inhibited receptors linked by a linear mechanism of gating at this site. Furthermore, the smFRET data suggest that allosteric inhibition by zinc occurs by an uncoupling of the agonist-induced changes at the extracellular domains from the gating motions leading to an apo-like state, while dizocilpine, a pore blocker, stabilizes multiple closely packed transmembrane states.

Effectiveness of Nonsurgical Interventions for Managing Adhesive Capsulitis in Patients With Diabetes: A Systematic Review.

OBJECTIVE: This systematic review evaluated the effectiveness of nonsurgical interventions for managing adhesive capsulitis (AC) in patients with diabetes on pain, function, and range of motion. DATA SOURCES: MEDLINE and other databases were searched for studies published in the last 20 years. STUDY SELECTION: Randomized controlled trials (RCTs) that assessed AC in people with diabetes and implemented 1 or a combination of physiotherapeutic interventions, corticosteroids, and manipulation under anesthesia (MUA) were eligible for inclusion. DATA EXTRACTION: The Cochrane Risk of Bias was used by 2 independent raters who met to achieve consensus. The quality of trials was assessed using Grading of Recommendations, Assessment, Development and Evaluations. Data extracted from the eligible studies included study design, participant characteristics and duration of symptoms, type of intervention, outcome measures, follow-up intervals, and research findings. DATA SYNTHESIS: Because of the lack of similar interventions, a narrative synthesis was conducted, and meta-analyses were not performed. The effect sizes or between-group differences of the interventions were reported. A total of 8 RCTs met the inclusion criteria: 4 addressed physiotherapeutic interventions, 3 corticosteroid injections, and 1 MUA. The effect sizes for physiotherapeutic interventions were 0.8-2.0, 0.9-2.0, and 1.0 for ROM, function, and pain, respectively, with the largest effect size (2.0) being reported for joint mobilization plus exercises. The effect sizes for corticosteroids were 0.2-0.5 and 0.1 for ROM and pain. The between-group improvement for MUA was 5.6 points on Constant Shoulder Score. CONCLUSION: Low-quality evidence suggests large effects of joint mobilization plus exercises on AC in people with diabetes, although confidence in this conclusion is limited due to the high risk of bias. Even weaker support was available for corticosteroid and MUA. Future high-quality RCTs are needed to determine the best intervention for managing AC in patients with diabetes.

The effect of diabetes on functional outcomes among individuals with distal radial fractures.

STUDY DESIGN: Prospective cohort study. INTRODUCTION: Diabetes is reported to adversely affect outcomes; however, its effect on distal radial fractures (DRF) is not well examined. PURPOSE OF THE STUDY: This study investigated the effect of diabetes on pain, hand function, physical health status, grip strength, and wrist and forearm range of motion among patients with DRF. METHODS: A total of 479 patients with DRF were classified into patients with and without diabetes based on self-report. Patient-Rated Wrist Evaluation assessed pain and hand function. The Short Form-12 assessed physical health status. Both questionnaires examined DRF recovery at baseline, 3 month, and 1 year. RESULTS: There was a significant improvement in Patient-Rated Wrist Evaluation scores over time (69 [19] to 25 [22]; 76 [15] to 20 [20] for patients with and without diabetes respectively, P < .01) with a significant interaction between time and diabetes (P < .01), indicating that patients with diabetes recovered more slowly than the rest of the cohort. There was an improvement over time on physical status (36 [12] to 45 [12]; 39 [9] to 50 [9], P < .01), grip strength (16 [7] to 24 [10]; 15 [9] to 24 [10], P < .01), and range of motion (flexion [42 {14} to 49 {15}; 43 {15} to 54 {14}, P < .01], extension [45 {11} to 52 {11}; 46 {13} to 53 {12}, P < .01], pronation [73 {10} to 77 {9}; 73 {11} to 78 {9}, P < .01], and supination [58 {17} to 65 {14}; 61 {17} to 70 {12}, P < .01]) for patients with and without diabetes, respectively. Patients with diabetes did not differ significantly in these secondary outcomes compared to the rest of the cohort. DISCUSSION AND CONCLUSION: Although individuals with diabetes had good outcomes, their recovery was slower than the rest of the cohort. This may be due to the adverse effect of hyperglycemia on bone tissues and small blood vessels. Future studies are required to assess how severity and duration of diabetes affect outcomes after DRF.

Treatment strategy by lactoperoxidase and lactoferrin combination: Immunomodulatory and antibacterial activity against multidrug-resistant Acinetobacter baumannii.

Lactoperoxidase (Lpo) and Lactoferrin (Lf) were extracted from camel colostrum milk and purified. The antibacterial activity of the two purified proteins was estimated against 14 isolates of multidrug resistance Acinetobacter baumannii. A combination of Lpo and Lf exhibited bactericidal action against A. baumannii in vitro. A mouse model of acute A. baumannii pneumonia was improved. The injection of combined Lpo and Lf after infection leads to significant clearance of A. baumannii rates in lung as well as blood culture P < 0.05 in comparing with control. Furthermore, the results showed a significant P < 0.05 reduction in the Bronchoalveolar lavage albumin concentration, lung injury and lactate dehydrogenase activity in comparing with control. In addition, the combination of Lpo and Lf treatment induced substantial elevation of IL-4 and IL10 concentrations p < 0.0 5 that helped to prevent damage caused by the inflammatory response. We concluded that combination of Lpo and Lf had a major inhibition effect against A. baumannii in comparing with imipenem as well as their immunomodulatory activity against resistant A. baumannii was increased by a synergistic effect of them as a crude combination. This study indicated two combined proteins consider as crucial strategy for practical treatment of pneumonia in the future.

Conformational Selection and Submillisecond Dynamics of the Ligand-binding Domain of the N-Methyl-d-aspartate Receptor.

The N-methyl-d-aspartate (NMDA) receptors are heteromeric non-selective cation channels that require the binding of glycine and glutamate for gating. Based on crystal structures, the mechanism of partial agonism at the glycine-binding site is thought to be mediated by a shift in the conformational equilibrium between an open clamshell and a closed clamshell-like structure of the bilobed ligand-binding domain (LBD). Using single-molecule Förster resonance energy transfer (smFRET) and multiparameter fluorescence detection, which allows us to study the conformational states and dynamics in the submillisecond time scale, we show that there are at least three conformational states explored by the LBD: the low FRET, medium FRET, and high FRET states. The distance of the medium and low FRET states corresponds to what has been observed in crystallography structures. We show that the high FRET state, which would represent a more closed clamshell conformation than that observed in the crystal structure, is most likely the state initiating activation, as evidenced by the fact that the fraction of the protein in this state correlates well with the extent of activation. Furthermore, full agonist bound LBDs show faster dynamic motions between the medium and high FRET states, whereas they show slower dynamics when bound to weaker agonists or to antagonists.

Two novel roles of buffalo milk lactoperoxidase, antibiofilm agent and immunomodulator against multidrug resistant Salmonella enterica serovar Typhi and Listeria monocytogenes.

The increasing occurrence of multidrug resistant bacteria causing bacteremia infection, constitutes a major health problem, difficult-to-treat bacteremia due to its ability to form biofilm. Buffalo milk lactoperoxidase (BMLpo) is effective and safe to use as bacteriostatic agent. The MIC of BMLpo and amikacin were used to evaluate the antibiofilm activity against resistant L. monocytogenes and S. typhi. Prophylactic effects of BMLpo against L. monocytogenes and S. typhi bacteremia in vivo have been tested and ELISA test used to evaluate serum cytokines. Significant antibiofilm activity of BMLpo observed against the highest biofilm producer isolates. Our results showed that the prophylactic effect of BMLpo in BALB/c mice bacteremic model. A significant clearance of L. monocytogenes and S. typhi, investigated in blood and different organs tissues in BMLpo-treated infected groups when compared to the non-treated groups. Further, analysis of serum cytokines levels revealed that BMLpo prophylaxis modulates their release in different way when it compared to the control. This study showed, BMLpo effects as an alternative antibiofilm agent to compact gram negative pathogens, and protects the host against bacteremia infection. Moreover, the BMLpo role as an immunomodulatory. These investigations indicated the BMLpo crucial role in the practical clinical applications.

The effects of diurnal Ramadan fasting on energy expenditure and substrate oxidation in healthy men.

The study aimed to examine the effects of diurnal Ramadan fasting (RF) on substrate oxidation, energy production, blood lipids and glucose as well as body composition. Nine healthy Muslim men (fasting (FAST) group) and eight healthy non-practicing men (control (CNT) group) were assessed pre- and post-RF. FAST were additionally assessed at days 10, 20 and 30 of RF in the morning and evening. Body composition was determined by hydrodensitometry, substrate oxidation and energy production by indirect calorimetry, blood metabolic profile by biochemical analyses and energy balance by activity tracker recordings and food log analyses. A significant group×time interaction revealed that chronic RF reduced body mass and adiposity in FAST, without changing lean mass, whereas CNT subjects remained unchanged. In parallel to these findings, a significant main diurnal effect (morning v. evening) of RF on substrate oxidation (a shift towards lipid oxidation) and blood metabolic profile (a decrease in glucose and an increase in total cholesterol and TAG levels, respectively) was observed, which did not vary over the course of the Ramadan. In conclusion, although RF induces diurnal metabolic adjustments (morning v. evening), no carryover effect was observed throughout RF despite the extended daily fasting period (18·0 (sd 0·3) h) and changes in body composition.

Phospholamban and sarcolipin: Are they functionally redundant or distinct regulators of the Sarco(Endo)Plasmic Reticulum Calcium ATPase?

In muscle, the Sarco(Endo)plasmic Reticulum Calcium ATPase (SERCA) activity is regulated by two distinct proteins, PLB and SLN, which are highly conserved throughout vertebrate evolution. PLB is predominantly expressed in the cardiac muscle, while SLN is abundant in skeletal muscle. SLN is also found in the cardiac atria and to a lesser extent in the ventricle. PLB regulation of SERCA is central to cardiac function, both at rest and during extreme physiological demand. Compared to PLB, the physiological relevance of SLN remained a mystery until recently and some even thought it was redundant in function. Studies on SLN suggest that it is an uncoupler of the SERCA pump activity and can increase ATP hydrolysis resulting in heat production. Using genetically engineered mouse models for SLN and PLB, we showed that SLN, not PLB, is required for muscle-based thermogenesis. However, the mechanism of how SLN binding to SERCA results in uncoupling SERCA Ca(2+) transport from its ATPase activity remains unclear. In this review, we discuss recent advances in understanding how PLB and SLN differ in their interaction with SERCA. We will also explore whether structural differences in the cytosolic domain of PLB and SLN are the basis for their unique function and physiological roles in cardiac and skeletal muscle.

Sarcolipin Is a Key Determinant of the Basal Metabolic Rate, and Its Overexpression Enhances Energy Expenditure and Resistance against Diet-induced Obesity.

Sarcolipin (SLN) is a novel regulator of sarcoplasmic reticulum Ca(2+) ATPase (SERCA) in muscle. SLN binding to SERCA uncouples Ca(2+) transport from ATP hydrolysis. By this mechanism, SLN promotes the futile cycling of SERCA, contributing to muscle heat production. We recently showed that SLN plays an important role in cold- and diet-induced thermogenesis. However, the detailed mechanism of how SLN regulates muscle metabolism remains unclear. In this study, we used both SLN knockout (Sln(-/-)) and skeletal muscle-specific SLN overexpression (Sln(OE)) mice to explore energy metabolism by pair feeding (fixed calories) and high-fat diet feeding (ad libitum). Our results show that, upon pair feeding, Sln(OE) mice lost weight compared with the WT, but Sln(-/-) mice gained weight. Interestingly, when fed with a high-fat diet, Sln(OE) mice consumed more calories but gained less weight and maintained a normal metabolic profile in comparison with WT and Sln(-/-) mice. We found that oxygen consumption and fatty acid oxidation were increased markedly in Sln(OE) mice. There was also an increase in both mitochondrial number and size in Sln(OE) muscle, together with increased expression of peroxisome proliferator-activated receptor δ (PPARδ) and PPAR γ coactivator 1 α (PGC1α), key transcriptional activators of mitochondrial biogenesis and enzymes involved in oxidative metabolism. These results, taken together, establish an important role for SLN in muscle metabolism and energy expenditure. On the basis of these data we propose that SLN is a novel target for enhancing whole-body energy expenditure.