Tissue Expansion: Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio (Adv. Sci. 22/2019)

Abstract Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. We recently identified LIM domain only 3 (LMO3) in human mature visceral adipocytes; however, its function in these cells is currently unknown. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high-fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics, as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain or loss of LMO3 expression, respectively. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. LMO3 expression in eWAT significantly improved insulin sensitivity and healthy visceral adipose tissue expansion in diet-induced obesity, paralleled by increased serum adiponectin. In vitro, LMO3 expression in 3T3-L1 adipocytes increased PPARγ transcriptional activity, insulin-stimulated GLUT4 translocation and glucose uptake, as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. Mechanistically, LMO3 induced the PPARγ coregulator Ncoa1, which was required for LMO3 to enhance glucose uptake and mitochondrial oxidative gene expression. In human mature adipocytes, LMO3 overexpression promoted, while silencing of LMO3 suppressed mitochondrial oxidative capacity. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose metabolism, insulin sensitivity, mitochondrial function, and adiponectin secretion. Together with increased PPARγ activity and Ncoa1 expression, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity. Key messages LMO3 increases beneficial visceral adipose tissue expansion and insulin sensitivity in vivo. LMO3 increases glucose uptake and oxidative mitochondrial activity in adipocytes. LMO3 increases nuclear coactivator 1 (Ncoa1). LMO3-enhanced glucose uptake and mitochondrial gene expression requires Ncoa1.

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Risk factors for tissue expander infection in scar reconstruction: a retrospective cohort study of 2374 consecutive cases

Burns & Trauma ◽

10.1093/burnst/tkaa037 ◽

2020 ◽

Vol 8 ◽

Author(s):

Chen Dong ◽

Minhui Zhu ◽

Luguang Huang ◽

Wei Liu ◽

Hengxin Liu ◽

...

Keyword(s):

Risk Factors ◽

Logistic Regression ◽

Regression Analysis ◽

Treatment Failure ◽

Logistic Regression Analysis ◽

Disease Duration ◽

Multivariate Logistic Regression Analysis ◽

Tissue Expansion ◽

Multivariate Logistic Regression ◽

Hematoma Evacuation

Abstract Background Tissue expansion is used for scar reconstruction owing to its excellent clinical outcomes; however, the complications that emerge from tissue expansion hinder repair. Infection is considered a major complication of tissue expansion. This study aimed to analyze the perioperative risk factors for expander infection. Methods A large, retrospective, single-institution observational study was carried out over a 10-year period. The study enrolled consecutive patients who had undergone tissue expansion for scar reconstruction. Demographics, etiological data, expander-related characteristics and postoperative infection were assessed. Univariate and multivariate logistic regression analysis were performed to identify risk factors for expander infection. In addition, we conducted a sensitivity analysis for treatment failure caused by infection as an outcome. Results A total of 2374 expanders and 148 cases of expander infection were assessed. Treatment failure caused by infection occurred in 14 expanders. Multivariate logistic regression analysis identified that disease duration of ≤1 year (odds ratio (OR), 2.07; p < 0.001), larger volume of expander (200–400 ml vs <200 ml; OR, 1.74; p = 0.032; >400 ml vs <200 ml; OR, 1.76; p = 0.049), limb location (OR, 2.22; p = 0.023) and hematoma evacuation (OR, 2.17; p = 0.049) were associated with a high likelihood of expander infection. Disease duration of ≤1 year (OR, 3.88; p = 0.015) and hematoma evacuation (OR, 10.35; p = 0.001) were so related to high risk of treatment failure. Conclusions The rate of expander infection in patients undergoing scar reconstruction was 6.2%. Disease duration of <1 year, expander volume of >200 ml, limb location and postoperative hematoma evacuation were independent risk factors for expander infection.

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Repair Exposure of the Postauricular Tissue Expander Using the Modified Brent Method: A 7-Year Experience

Ear Nose & Throat Journal ◽

10.1177/01455613211007967 ◽

2021 ◽

pp. 014556132110079

Author(s):

Tongyu Cao ◽

Qingguo Zhang

Keyword(s):

Soft Tissue ◽

Skin Flap ◽

Tissue Expander ◽

Tissue Expansion ◽

Ear Reconstruction ◽

Lower Pole ◽

Tension Free ◽

Subsequent Exposure ◽

Free Closure ◽

Complicated Conditions

Objectives: Ear reconstruction is a challenging surgery for the complicated conditions in patients with microtia. The tissue expansion techniques were necessary and relatively safe for patients with insufficient soft tissue. However, complications such as necrosis of expanded flap and exposure of tissue expander limited the popularization of this method. This study described the use of modified Brent method to handle the exposure of the postauricular tissue expander. Methods: From January 2013 to December 2019, 27 ear reconstruction patients with trauma or necrosis on an expanded skin flap and subsequent exposure of tissue expander were treated with modified Brent method, which consisted of 3 stages: removal of the expander, tension-free closure of wound, and framework fabrication; elevation of reconstructed ear; lobule rotation; and minor modification. Results: Fifty-six percent of exposures occurred in the lower pole of the tissue expander. Exposure usually occurred 54.5 days after implantation. The majority of reconstructed ears had a satisfactory appearance and showed relatively stable outcomes. Only one case of cartilage exposure required revision surgery and was repaired by the temporoparietal fascia. Conclusion: With reasonable distribution of expanded flap, prolonged interval, and sutures under tension-free conditions, complications like the occurrence of trauma or necrosis-induced exposure of tissue expander can be repaired efficiently by a staging modified Brent method.

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Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening

Metals ◽

10.3390/met11050721 ◽

2021 ◽

Vol 11 (5) ◽

pp. 721

Author(s):

Yongjun Jeon ◽

Hyunseok Choi ◽

Dongearn Kim

Keyword(s):

Hot Stamping ◽

High Strength Steels ◽

High Strength ◽

Expansion Ratio ◽

Hardened Steel ◽

Continuous Increase ◽

Pilot Hole ◽

Experimental Apparatus ◽

Mechanical Fastening ◽

Hole Flanging

The recent stringent regulations on vehicle safety and reducing CO2 emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.

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A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle

Processes ◽

10.3390/pr9061051 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1051

Author(s):

Jungmo Oh ◽

Kichol Noh ◽

Changhee Lee

Keyword(s):

Compression Ratio ◽

Thermal Efficiency ◽

Engine Performance ◽

Thermodynamic Cycle ◽

Expansion Ratio ◽

Boost Pressure ◽

Miller Cycle ◽

Compression Pressure ◽

Air Mass ◽

Atkinson Cycle

The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.

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