Regulation of energy expenditure by mitochondrial dynamics in brown adipose tissue from subcellular to whole body level

Obesity is a disorder of energy imbalance in which energy intake exceeds energy expenditure (EEX). Brown adipose tissue (BAT) is unique in that it can increase whole body EEX when it is adrenergically activated. The thermogenic capacity of BAT is mediated by mitochondrial uncoupling through the activation of Uncoupling Protein 1 which uncouple respiration from ATP production. Mitochondria is a dynamic organelle that undergo continuous cycles of fusion and fission. Alteration in mitochondrial dynamics correlates with changes in energy efficiency in different cell types; however, its role in regulating EEX in BAT has not been investigated. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically-induced changes in EEX in BAT. Norepinephrine (NE) induces mitochondrial fragmentation in brown adipocytes (BA) though posttranslational modifications - phosphorylation and proteolytic cleavage -of mitochondrial dynamic proteins. NE-induced EEX is reduced in fission-deficient brown adipocytes while forced mitochondrial fragmentation increases the respiration in response to exogenous free fatty acids (FFAs) indicating increase in EEX. We further investigated whether forced mitochondrial fragmentation in BAT could be utilized as an approach to increase whole body EEX is response to FFA in vivo. We found that a mouse model with forced mitochondrial fragmentation in BAT (BAT-Mitofusin2-KO) gained less body weight and less fat mass and remained more glucose tolerant and insulin sensitive under high fat diet (HFD) compared to the wild type. Additionally, FFA oxidation was enhanced in BAT-Mitofusin2-KO mice indicated by lower respiratory exchange ratio. We also found that subcellular heterogeneity in dynamics leads to the generation of subpopulations of mitochondria with diverse bioenergetics characteristics within the same cell. We described that a subpopulation of mitochondria surrounding the lipid droplet in BA had higher ATP synthesis capacity, supported by higher ATP synthase protein expression and elongated morphology. We suggest that this subpopulation of mitochondria is responsible for addressing the ATP demand of the BA when it is not activated. In conclusion, changes to mitochondrial dynamics are required for BAT thermogenic activity and for the control of EEX efficiency from sub-cellular to the whole body level. Additionally, mitochondrial dynamics in BAT can regulate fatty acid oxidation.2018-06-15T00:00:00

Improving the Sphere-Packing Bound for Binary Codes over Memoryless Symmetric Channels

A lower bound on the minimum required code length of binary codes is obtained. The bound is obtained based on observing a close relation between the Ulam's liar game and channel coding. In fact, Spencer's optimal solution to the game is used to derive this new bound which improves the famous Sphere-Packing Bound.Comment: 5 pages,3 figures, Presented at the Forty-Seventh Annual Allerton Conference on Communication, Control, and Computing, Sep. 200

Annotated Raptor Codes

In this paper, an extension of raptor codes is introduced which keeps all the desirable properties of raptor codes, including the linear complexity of encoding and decoding per information bit, unchanged. The new design, however, improves the performance in terms of the reception rate. Our simulations show a 10% reduction in the needed overhead at the benchmark block length of 64,520 bits and with the same complexity per information bit.Comment: This paper has been Accepted for presentation in IEEE Information Theory Workshop (ITW) 2011, Paraty, Brazi

An innovative concept for rotating a goniolens

A goniolens holder was constructed to facilitate rotation of the lens while placed on the patient\u27s eye. The device consists of a ball-bearing1 mounted on the lens; the outer surface of the lens and bearing are grooved to facilitate independent rotation

Association between physical activity and risk of COVID-19 infection or clinical outcomes of the patients with COVID-19; A systematic review and meta-analysis

Objective:  Nowadays, the COVID-19 pandemic has caused serious consequences for global health and economy. The important question is whether the level of physical activity might influence the risk of COVID-19 incidence or clinical outcomes, including the severity or mortality of infected patients. The objective of this systematic review and meta-analysis is to evaluate the association between sufficient physical activity and incidence, hospitalization, severity, recovery, and mortality of COVID-19. Methods: A systematic search of Web of Sciences, PubMed, and Scopus between December 2019 and November 2021 in English language was conducted. Studies were screened based on the inclusion criteria, i.e. observational studies (case-control, prospective or retrospective longitudinal designs, and cross-sectional studies) which have determined the association of physical activity, exercise, sports participation, or sedentary behavior with COVID-19 incidence or outcomes, including mortality, severity, recovery and hospitalization in healthy population or population with any specific comorbidity. Results: Based on eligibility criteria, 27 articles were finally included in the qualitative synthesis. The meta-analysis of five studies evaluating association of physical activity and COVID-19 mortality showed weighted OR of OR of 0.61 (CI 95%: 0.50- 0.75) with heterogeneity (I2= 45.8%, P<0.001) and in seven studies regarding physical activity and COVID-19 hospitalization, weighted OR was 0.541 (CI 95% :0.491 -0.595) with heterogeneity (I2=81.7%, P<0.001). Conclusion: Participating in sufficient physical activity might decrease COVID-19 related hospitalization and mortality. Developing programs to increase physical activity during the COVID-19 pandemic might be an appropriate health strategy