Sympathetic neuro-adipose connections mediate leptin-driven lipolysis.

Leptin is a hormone produced by the adipose tissue that acts in the brain, stimulating white fat breakdown. We find that the lipolytic effect of leptin is mediated through the action of sympathetic nerve fibers that innervate the adipose tissue. Using intravital two-photon microscopy, we observe that sympathetic nerve fibers establish neuro-adipose junctions, directly "enveloping" adipocytes. Local optogenetic stimulation of sympathetic inputs induces a local lipolytic response and depletion of white adipose mass. Conversely, genetic ablation of sympathetic inputs onto fat pads blocks leptin-stimulated phosphorylation of hormone-sensitive lipase and consequent lipolysis, as do knockouts of dopamine ß-hydroxylase, an enzyme required for catecholamine synthesis. Thus, neuro-adipose junctions are necessary and sufficient for the induction of lipolysis in white adipose tissue and are an efferent effector of leptin action. Direct activation of sympathetic inputs to adipose tissues may represent an alternative approach to induce fat loss, circumventing central leptin resistance. PAPERCLIP.

The Impact of Marijuana Use on Postoperative Outcomes in Abdominal-based Free Flap Breast Reconstruction.

BACKGROUND: There is an increasing prevalence of marijuana use in the general population yet clinical studies on marijuana's effect on surgical outcomes remain limited. Marijuana's effect on wound healing, venous thromboembolism (VTE) due to endothelial inflammation, and bleeding due to inhibited platelet function have been cited based on animal models but have not been evaluated clinically in patients undergoing microsurgical reconstruction. METHODS: Retrospective chart review was performed on all patients who underwent abdominal-based free flap breast reconstruction in a single institute from August 2018 to December 2022. Patient self-reported marijuana use, demographics, total narcotic use during hospitalization converted to oral morphine milligram equivalent (MME), and 90-day complications were collected and compared. RESULTS: A total of 162 patients were included and 13 patients (8.5%) had reported marijuana use on presurgical history. Marijuana users are more likely to be younger and report concurrent nicotine smoking. Marijuana users were also at a significantly elevated risk of developing symptomatic VTE (15 vs. 1%; odds ratio (OR) 13.4 [95% confidence interval (CI) 1.71-104.2]; p = 0.01) and marijuana use remained a significant risk factor with multivariate analysis. On postoperative 90-day complications, there was no increased risk of flap loss, reoperation, postoperative transfusion, or hematoma associated with marijuana use, and no significantly increased risk for overall donor or recipient site complications. Marijuana users required significantly more narcotics for pain control during hospitalization (100 ± 77 vs. 49 ± 45 MME; p = 0.0003), although they had similar lengths of stay, achievement of mobilization on post operative day (POD)1, and maximal pain scores. CONCLUSION: Marijuana use increases the risks of postoperative VTE and increased postoperative narcotic requirements in patients who underwent abdominal-based free flap breast reconstruction. Future prospective cohort study is required to further understand marijuana-associated risks in microsurgical procedures.

Visual Perception of Breast Free Flap Size Is Influenced by Radiation Changes of Surrounding Tissue.

BACKGROUND: Microsurgical reconstruction for bilateral mastectomy defects after unilateral radiation often results in asymmetry, despite both flap tissues never being radiated. METHODS: Photos of 16 patients who received prior radiation to one breast and underwent bilateral abdominal free flap reconstruction were taken postoperatively. Layperson and expert assessment were attained via online crowdsourcing and a panel of attending surgeons and senior residents. Stratification by interflap weight differences was done for subanalysis. RESULTS: A total of 399 laypersons responded, with the majority (57.3%) reporting that the radiated breast appeared smaller than the nonradiated breast. When the photos were stratified by interflap weight differences, the photos with the radiated side flap weight over 3% more than nonradiated side were significantly more likely to be perceived by laypersons as the same size (odds ratio [OR] = 2.7; p < 0.001) and of similar aesthetic (OR = 1.9; p < 0.001) when compared with photos with same-sized flaps. Of the expert responses (n = 16), the radiated side was perceived as smaller 72.3% of the time and the nonradiated side appeared more aesthetic 52.7% of the time. Contrary to layperson responses, the experts tend to report the radiated side as smaller despite varying flap weight. Interestingly, expert raters were significantly more likely to rate the flaps of equal aesthetics when the radiated side has a flap larger by 3% or more (OR = 3.6; p < 0.001). CONCLUSION: Higher aesthetic scores were noted when larger flaps were inset to the radiated envelope by both laypersons and experts, suggesting potential technical refinement in reconstructive outcomes.

Postoperative Magnesium Sulfate Repletion Decreases Narcotic Use in Abdominal-Based Free Flap Breast Reconstruction.

BACKGROUND: Microsurgical breast reconstruction after mastectomy is now the standard of care for breast cancer patients. However, the costs and resources involved in free flap reconstruction can vary across different medical settings. To enhance patient outcomes in a cost-effective manner, we investigated the effect of intravenous magnesium sulfate (IV Mg) on postoperative opioid usage in this context. METHODS: A retrospective chart review was performed on all consecutive patients who underwent abdominal-based free flap breast reconstruction in a single institute following an enhanced recovery after surgery (ERAS) protocol. Patients who received IV Mg were compared with those who did not receive supplementation. Serum magnesium levels at different time points, narcotic consumption in units of oral morphine milligram equivalents (MMEs), and other postoperative recovery parameters were compared. RESULTS: Eighty-two patients were included. Those who received IV Mg on postoperative day 0 (n = 67) showed significantly lower serum magnesium levels before repletion (1.5 vs. 1.7 mg/dL, p = 0.004) and significantly higher levels on postoperative day 1 after repletion (2.2 vs. 1.7 mg/dL, p = 0.0002) compared to patients who received no magnesium repletion (n = 13). While both groups required a similar amount of narcotics on postoperative day 0 (20.2 vs. 13.2 MMEs, p = 0.2), those who received IV Mg needed significantly fewer narcotics for pain control on postoperative day 1 (12.2 MMEs for IV Mg vs. 19.8 MMEs for No Mg, p = 0.03). Recovery parameters, including maximal pain scores, postoperative mobilization, and length of hospital stay, did not significantly differ between the two groups. CONCLUSION: This is the first study to describe the potential analgesic benefits of routine postoperative magnesium repletion in abdominal-based free flap reconstruction. Further research is necessary to fully understand the role of perioperative magnesium supplementation as part of an ERAS protocol.

An Anatomical Feasibility Study on the Use of the Hypoglossal and Hemihypoglossal Nerve as a Donor Motor Nerve for Free Functioning Muscle Transfer in Upper Extremity Reconstruction.

PURPOSE: Brachial plexus injuries (BPI) with complete root avulsions remains a clinical challenge due to a paucity of nerves available for nerve transfer and innervation of free functioning muscle transfers (FFMT). The hypoglossal and hemihypoglossal nerve has not been studied as a donor nerve option for FFMTs in brachial plexus reconstruction, despite successful outcomes of hypoglossal nerve transfers in facial reanimation surgery. We hypothesized that the hypoglossal nerve could be an appropriate candidate for surgical repair of BPI using FFMT. METHODS: A cadaveric study was performed to determine the anatomic feasibility of using the hypoglossal and hemihypoglossal nerves as donor nerves to neurotize the gracilis or latissimus dorsi muscle in an FFMT to restore elbow flexion. Twelve cadavers (6 males and 6 females) were studied. The hypoglossal nerve, thoracodorsal nerve, and obturator nerve branches to the gracilis muscle were dissected, measured, and analyzed. RESULTS: The average length of the hypoglossal nerve was 6.3 ± 0.5 cm in both sexes. The average distance between the lowest point of the hypoglossal nerve and the lateral clavicle was 8.4 ± 1.3 cm in males and 7.7 ± 0.8 cm in females. When the hypoglossal nerve was transected distally, the average distance to the clavicle was 4.5 ± 1.6 cm in males and 3.8 ± 1.5 cm in females. CONCLUSIONS: The maximum theoretical length of the donor nerve required to perform an adequate FFMT using the hypoglossal nerve was 8.9 ± 1.2 cm, which was well exceeded by the lengths of the thoracodorsal nerve (14.5 ± 1.3 cm) and nerve to the gracilis muscle (12.7 ± 1.7 cm). CLINICAL RELEVANCE: This cadaveric study demonstrated that the hypoglossal or hemihypoglossal nerves may be used as potential motor donor nerves to innervate a free gracilis or latissimus dorsi muscle transfer for the restoration of elbow flexion via a direct nerve transfer without the need for nerve grafting.

Hemostatic Agents Do Not Significantly Affect Seroma Formation in Abdominal Body Contouring.

BACKGROUND: Objective: Seroma formation is plaguing complication in abdominal body contouring surgery (ABCS) that has been loosely associated with the use of intraoperative hemostatic agents. The aim of this study was to investigate the association between hemostatic agent usage and seroma development following ABCS. METHODS: A retrospective review of patients undergoing ABCS between 2010 and 2020 was completed. Cases who received hemostatic agents were matched to controls (1:2) based on potential confounders including age, BMI, and ASA score. Demographic data, operative details, and postoperative complications including development of seroma, hematoma, venous thromboembolism, wound dehiscence, and delayed wound healing were collected. RESULTS: Seven hundred and seven patients were included in the study. Sixty-five patients (9.2%) received at least one hemostatic agent. The most used agents were topical thrombin (n = 33, 50.1%), dry matrices including oxidized cellulose, microporous polysaccharides, and absorbable gelatin matrices (n = 15, 23.1%) followed by combination fibrin sealant/thrombin preparations (n = 9, 14.0%). No significant differences with respect to demographic data or medical comorbidities between the cases and controls were identified. Bivariate analysis demonstrated no significant differences in the rate of development of seroma (OR: 0.83, 95% confidence interval [CI] = 0.23-1.99, p = 0.781), hematoma (OR: 3.72, 95% confidence interval [CI] = 0.95-14.65, p = 0.060), venous thromboembolism (OR: 0.40, 95% confidence interval [CI] = 0.44-3.81, p = 0.433). CONCLUSION: Hemostatic agent use, regardless of type, does not significantly affect the risk of seroma, hematoma, and venous thromboembolism development, nor does it influence the rates of delayed wound healing or wound dehiscence. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Language Disparity Predicts Poor Patient-Reported Outcome and Follow-Up in Microsurgical Breast Reconstruction.

BACKGROUND: Patients with limited English proficiency (LEP) have starkly different health care experiences compared with their English-proficient counterparts. The authors aim to examine the link between LEP and postoperative outcomes in patients undergoing microsurgical breast reconstruction. METHODS: A retrospective review of all patients who underwent abdominal-based microsurgical breast reconstruction at our institution between 2009 and 2019 was performed. Variables collected included patient demographics, language status, interpreter usage, perioperative complications, follow-up visits, and self-reported outcomes (Breast-Q). Pearson's χ 2 test, Student's t-test, odds ratio analysis, and regression modeling were used for analysis. RESULTS: A total of 405 patients were included. LEP patients comprised 22.22% of the overall cohort with 80% of LEP patients utilizing interpreter services. LEP patients reported significantly lower satisfaction with an abdominal appearance at the 6-month follow-up and lower physical and sexual well-being scores at the 1-year follow-up (p = 0.05, 0.02, 0.01, respectively). Non-LEP patients had significantly longer operative times (539.6 vs. 499.3 minutes, p = 0.024), were more likely to have postoperative donor site revisions (p = 0.05), and more likely to receive preoperative neuraxial anesthesia (p = 0.01). After adjusting for confounders, LEP stats was associated with 0.93 fewer follow-up visits (p = 0.02). Interestingly, compared with LEP patients who did not receive interpreter services, LEP patients who did had 1.98 more follow-up visits (p = 0.02). There were no significant differences in emergency room visits or complications between the cohorts. CONCLUSION: Our findings suggest that language disparities exist within microsurgical breast reconstruction and underscore the importance of effective, language-conscious communication between surgeon and patient.

Women in Microsurgery Fellowships: Trends and Impact on Future Practice Patterns.

BACKGROUND: While the number of female plastic surgeons has continued to increase over time, plastic surgery has historically been a male-dominated profession with only 15% of practicing plastic surgeons being female. Microsurgery, as a subspecialty, has been long perceived as an even more male-centric career path. The objective of this study was to determine the representation of females in the subspecialty field of microsurgery and the impact of microsurgical fellowship training. METHODS: A review of all microsurgery fellowship programs participating in the microsurgery fellowship match from 2010 to 2019 were analyzed. Fellows were identified through fellowship Web site pages or direct contact with fellowship program coordinators and directors. The current type of practice and performance of microsurgery were also identified through a Web search and direct contact with fellowship program coordinators and directors. RESULTS: A total of 21 programs and 317 fellows over a 10-year period were analyzed. Over this 10-year period, there was a total of 100 (31.5%) female microsurgery fellows and 217 (68.5%) male microsurgery fellows. There was a small, statistically insignificant increase in the yearly percentage of female microsurgery fellows over this 10-year period with an average yearly increase of 2.7% (p = 0.60; 95% confidence interval: -6.9 to 13.2%). There were significantly fewer females who continued to practice microsurgery compared to males (75 [75.0%] vs. 186 [85.7%], p = 0.02). There was no significant difference in the current practice types (academic, private, and nonacademic hospital) between females and males (p = 0.29). CONCLUSION: Women are underrepresented in the field of microsurgery to a similar extent as they are underrepresented in overall plastic surgery. While there is a small insignificant increase in the number of female microsurgery fellows every year, a significantly smaller proportion of females continue to practice microsurgery compared to males.

A noncanonical PPARγ/RXRα-binding sequence regulates leptin expression in response to changes in adipose tissue mass.

Leptin expression decreases after fat loss and is increased when obesity develops, and its proper quantitative regulation is essential for the homeostatic control of fat mass. We previously reported that a distant leptin enhancer 1 (LE1), 16 kb upstream from the transcription start site (TSS), confers fat-specific expression in a bacterial artificial chromosome transgenic (BACTG) reporter mouse. However, this and the other elements that we identified do not account for the quantitative changes in leptin expression that accompany alterations of adipose mass. In this report, we used an assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) to identify a 17-bp noncanonical peroxisome proliferator-activated receptor gamma (PPARγ)/retinoid X receptor alpha (RXRα)-binding site, leptin regulatory element 1 (LepRE1), within LE1, and show that it is necessary for the fat-regulated quantitative control of reporter (luciferase) expression. While BACTG reporter mice with mutations in this sequence still show fat-specific expression, luciferase is no longer decreased after food restriction and weight loss. Similarly, the increased expression of leptin reporter associated with obesity in ob/ob mice is impaired. A functionally analogous LepRE1 site is also found in a second, redundant DNA regulatory element 13 kb downstream of the TSS. These data uncouple the mechanisms conferring qualitative and quantitative expression of the leptin gene and further suggest that factor(s) that bind to LepRE1 quantitatively control leptin expression and might be components of a lipid-sensing system in adipocytes.

Reanalysis of parabiosis of obesity mutants in the age of leptin.

In this study we set out to explain the differing effects of parabiosis with genetically diabetic (db) mice versus administration of recombinant leptin. Parabiosis of db mutant, which overexpress leptin, to wildtype (WT) or genetically obese (ob) mice has been reported to cause death by starvation, whereas leptin infusions do not produce lethality at any dose or mode of delivery tested. Leptin is not posttranslationally modified other than a single disulphide bond, raising the possibility that it might require additional factor(s) to exert the maximal appetite-suppressing effect. We reconfirmed the lethal effect of parabiosis of db mutant on WT mice and further showed that this lethality could not be rescued by administration of ghrelin or growth hormone. We then initiated a biochemical fractionation of a high-molecular-weight leptin complex from human plasma and identified clusterin as a major component of this leptin-containing complex. However, in contrast to previous reports, we failed to observe a leptin-potentiating effect of either exogenous or endogenous clusterin, and parabiosis of db clusterin(-/-) double-mutant to WT mice still caused lethality. Intriguingly, in parabiotic pairs of two WT mice, leptin infusion into one of the mice led to an enhanced starvation response during calorie restriction as evidenced by increased plasma ghrelin and growth-hormone levels. Moreover, leptin treatment resulted in death of the parabiotic pairs. These data suggest that the appetite suppression in WT mice after parabiosis to db mutants is the result of induced hyperleptinemia combined with the stress or other aspect(s) of the parabiosis procedure.

Three phosphatidylglycerol-phosphate phosphatases in the inner membrane of Escherichia coli.

The phospholipids of Escherichia coli consist mainly of phosphatidylethanolamine, phosphatidylglycerol (PG), and cardiolipin. PG makes up ∼25% of the cellular phospholipid and is essential for growth in wild-type cells. PG is synthesized on the inner surface of the inner membrane from cytidine diphosphate-diacylglycerol and glycerol 3-phosphate, generating the precursor phosphatidylglycerol-phosphate (PGP). This compound is present at low levels (∼0.1% of the total lipid). Dephosphorylation of PGP to PG is catalyzed by several PGP-phosphatases. The pgpA and pgpB genes, which encode structurally distinct PGP-phosphatases, were identified previously. Double deletion mutants lacking pgpA and pgpB are viable and still make PG, suggesting the presence of additional phosphatase(s). We have identified a third PGP-phosphatase gene (previously annotated as yfhB but renamed pgpC) using an expression cloning strategy. A mutant with deletions in all three phosphatase genes is not viable unless covered by a plasmid expressing either pgpA, pgpB, or pgpC. When the triple mutant is covered with the temperature-sensitive plasmid pMAK705 expressing any one of the three pgp genes, the cells grow at 30 but not 42 °C. As growth slows at 42 °C, PGP accumulates to high levels, and the PG content declines. PgpC orthologs are present in many other bacteria.

Limitation of adipose tissue by the number of embryonic progenitor cells.

Adipogenesis in adulthood replaces fat cells that turn over and can contribute to the development of obesity. However, the proliferative potential of adipocyte progenitors in vivo is unknown (Faust et al., 1976; Faust et al., 1977; Hirsch and Han, 1969; Johnson and Hirsch, 1972). We addressed this by injecting labeled wild-type embryonic stem cells into blastocysts derived from lipodystrophic A-ZIP transgenic mice, which have a genetic block in adipogenesis. In the resulting chimeric animals, wild-type ES cells are the only source of mature adipocytes. We found that when chimeric animals were fed a high-fat-diet, animals with low levels of chimerism showed a significantly lower adipose tissue mass than animals with high levels of chimerism. The difference in adipose tissue mass was attributed to variability in the amount of subcutaneous adipose tissue as the amount of visceral fat was independent of the level of chimerism. Our findings thus suggest that proliferative potential of adipocyte precursors is limited and can restrain the development of obesity.

Dysregulation of a long noncoding RNA reduces leptin leading to a leptin-responsive form of obesity.

Quantitative changes in leptin concentration lead to alterations in food intake and body weight, but the regulatory mechanisms that control leptin gene expression are poorly understood. Here we report that fat-specific and quantitative leptin expression is controlled by redundant cis elements and trans factors interacting with the proximal promoter together with a long noncoding RNA (lncOb). Diet-induced obese mice lacking lncOb show increased fat mass with reduced plasma leptin levels and lose weight after leptin treatment, whereas control mice do not. Consistent with this finding, large-scale genetic studies of humans reveal a significant association of single-nucleotide polymorphisms (SNPs) in the region of human lncOb with lower plasma leptin levels and obesity. These results show that reduced leptin gene expression can lead to a hypoleptinemic, leptin-responsive form of obesity and provide a framework for elucidating the pathogenic mechanism in the subset of obese patients with low endogenous leptin levels.

Twelve-Minute Daily Yoga Regimen Reverses Osteoporotic Bone Loss.

OBJECTIVE: Assess the effectiveness of selected yoga postures in raising bone mineral density (BMD). METHODS: Ten-year study of 741 Internet-recruited volunteers comparing preyoga BMD changes with postyoga BMD changes. OUTCOME MEASURES: Dual-energy x-ray absorptiometric scans. Optional radiographs of hips and spine and bone quality study (7 Tesla). RESULTS: Bone mineral density improved in spine, hips, and femur of the 227 moderately and fully compliant patients. Monthly gain in BMD was significant in spine (0.0029 g/cm2, P = .005) and femur (0.00022 g/cm2, P = .053), but in 1 cohort, although mean gain in hip BMD was 50%, large individual differences raised the confidence interval and the gain was not significant for total hip (0.000357 g/cm2). No yoga-related serious injuries were imaged or reported. Bone quality appeared qualitatively improved in yoga practitioners. CONCLUSION: Yoga appears to raise BMD in the spine and the femur safely.

Corrigendum to "Nuclear Factor-Y is an adipogenic factor that regulates leptin gene expression"[Mol Metab 4 (2015) 392-405].

[This corrects the article DOI: 10.1016/j.molmet.2015.02.002.].

Nuclear Factor-Y is an adipogenic factor that regulates leptin gene expression.

OBJECTIVE: Leptin gene expression is highly correlated with cellular lipid content in adipocytes but the transcriptional mechanisms controlling leptin expression in vivo are poorly understood. In this report, we set out to identify cis- and trans-regulatory elements controlling leptin expression. METHODS: Leptin-BAC luciferase transgenic mice combining with other computational and molecular techniques were used to identify transcription regulatory elements including a CCAAT-binding protein Nuclear Factor Y (NF-Y). The function of NF-Y in adipocyte was studied in vitro with 3T3-L1 cells and in vivo with adipocyte-specific knockout of NF-Y. RESULTS: Using Leptin-BAC luciferase mice, we showed that DNA sequences between -22 kb and +8.8 kb can confer quantitative expression of a leptin reporter. Computational analysis of sequences and gel shift assays identified a 32 bp sequence (chr6: 28993820-2899385) consisting a CCAAT binding site for Nuclear Factor Y (NF-Y) and this was confirmed by a ChIP assay in vivo. A deletion of this 32 bp sequence in the -22 kb to +8.8 kb leptin-luciferase BAC reporter completely abrogates luciferase reporter activity in vivo. RNAi mediated knockdown of NF-Y interfered with adipogenesis in vitro and adipocyte-specific knockout of NF-Y in mice reduced expression of leptin and other fat specific genes in vivo. Further analyses of the fat specific NF-Y knockout revealed that these animals develop a moderately severe lipodystrophy that is remediable with leptin therapy. CONCLUSIONS: These studies advance our understanding of leptin gene expression and show that NF-Y controls the expression of leptin and other adipocyte genes and identifies a new form of lipodystrophy.