Tissue oxygenation in obese and non-obese patients during laparoscopy

Acute inhibition of iron-sulfur cluster biosynthesis disrupts metabolic flexibility in mice

Iron-sulfur clusters (ISCs) are cell-essential cofactors present in ∼60 proteins including subunits of OXPHOS complexes I-III, DNA polymerases, and iron-sensing proteins. Dysfunctions in ISC biosynthesis are associated with anemias, neurodegenerative disorders, and metabolic diseases. To assess consequences of acute ISC inhibition in a whole body setting, we developed a mouse model in which key ISC biosynthetic enzyme NFS1 can be acutely and reversibly suppressed. Contrary to in vitro ISC inhibition and pharmacological OXPHOS suppression, global NFS1 inhibition rapidly enhances lipid utilization and decreases adiposity without affecting caloric intake and physical activity. ISC proteins decrease, including key proteins involved in OXPHOS (SDHB), lipoic acid synthesis (LIAS), and insulin mRNA processing (CDKAL1), causing acute metabolic inflexibility. Age-related metabolic changes decelerate loss of adiposity substantially prolonged survival of mice with NFS1 inhibition. Thus, the observation that ISC metabolism impacts organismal fuel choice will aid in understanding the mechanisms underlying ISC diseases with increased risk for diabetes.

Graphical abstract

Highlights

Acute ISC inhibition leads to rapid loss of adiposity in miceMulti-metabolic pathway disruption upon ISC deficiency blocks energy storageNfs1 inhibition induces glucose dyshomeostasis due to ISC deficiency in β-cellsEnergy distress caused by inhibition of ISC synthesis is attenuated in aged mice.

Debunking the "Obesity Paradox": Obesity is Associated With Adverse Outcomes in Emergency General Surgery

INTRODUCTION

Obesity is increasingly prevalent both nationwide and in the emergency general surgery (EGS) population. While previous studies have shown that obesity may be protective against mortality following EGS procedures, the association between body mass index (BMI) and postoperative outcomes, as well as intraoperative decision-making, remains understudied.

METHODS

The National Surgical Quality Improvement Program 2015-2019 database was used to identify all adult patients undergoing an open abdominal or abdominal wall procedure for EGS conditions. Our outcomes included 30-d postoperative mortality, composite 30-d morbidity, delayed fascial closure, reoperation, operative time, and hospital length of stay (LOS). Multivariable logistic regression models were used to explore the association between BMI and each outcome of interest while adjusting for patient demographics, comorbidities, laboratory tests, preoperative and intraoperative variables.

RESULTS

We identified 78,578 patients, of which 3121 (4%) were categorized as underweight, 23,661 (30.1%) as normal weight, 22,072 (28.1%) as overweight, 14,287 (18.2%) with class I obesity, 7370 (9.4%) with class II obesity, and 8067 (10.3%) with class III obesity. Class III obesity was identified as a risk factor for 30-d postoperative morbidity (adjusted odds ratio 1.14, 95% CI, 1.03-1.26, P < 0.01). An increase in obesity class was also associated with a stepwise increase in the risk of undergoing delayed fascial closure, experiencing a prolonged operative time, and having an extended LOS.

CONCLUSIONS

Obesity class was associated with an increase in delayed fascial closure, longer operative time, higher reoperation rates, and extended hospital LOS. Further studies are needed to explore how a patient's BMI impacts intraoperative factors, influences surgical decision-making, and contributes to hospital costs.

Understanding wound healing in obesity

Obesity has become more prevalent in the global population. It is associated with the development of several diseases including diabetes mellitus, coronary heart disease, and metabolic syndrome. There are a multitude of factors impacted by obesity that may contribute to poor wound healing outcomes. With millions worldwide classified as obese, it is imperative to understand wound healing in these patients. Despite advances in the understanding of wound healing in both healthy and diabetic populations, much is unknown about wound healing in obese patients. This review examines the impact of obesity on wound healing and several animal models that may be used to broaden our understanding in this area. As a growing portion of the population identifies as obese, understanding the underlying mechanisms and how to overcome poor wound healing is of the utmost importance.

Hypoxia as a Double-Edged Sword to Combat Obesity and Comorbidities

The global epidemic of obesity is tightly associated with numerous comorbidities, such as type II diabetes, cardiovascular diseases and the metabolic syndrome. Among the key features of obesity, some studies have suggested the abnormal expansion of adipose-tissue-induced local endogenous hypoxic, while other studies indicated endogenous hyperoxia as the opposite trend. Endogenous hypoxic aggravates dysfunction in adipose tissue and stimulates secretion of inflammatory molecules, which contribute to obesity. In contrast, hypoxic exposure combined with training effectively generate exogenous hypoxic to reduce body weight and downregulate metabolic risks. The (patho)physiological effects in adipose tissue are distinct from those of endogenous hypoxic. We critically assess the latest advances on the molecular mediators of endogenous hypoxic that regulate the dysfunction in adipose tissue. Subsequently we propose potential therapeutic targets in adipose tissues and the small molecules that may reverse the detrimental effect of local endogenous hypoxic. More importantly, we discuss alterations of metabolic pathways in adipose tissue and the metabolic benefits brought by hypoxic exercise. In terms of therapeutic intervention, numerous approaches have been developed to treat obesity, nevertheless durability and safety remain the major concern. Thus, a combination of the therapies that suppress endogenous hypoxic with exercise plans that augment exogenous hypoxic may accelerate the development of more effective and durable medications to treat obesity and comorbidities.

Of mice and men: Considerations on adipose tissue physiology in animal models of obesity and human studies

The ever-increasing burden of obesity demands a better pathophysiological understanding, especially regarding adipose tissue pathophysiology. Animal models of obesity are of great importance in investigating potential mechanisms and implications of obesity. Many issues should be considered while interpreting the preclinical results as anatomical and pathophysiological differences exist among species. Importantly, the natural history of obesity development differs considerably. An important example of conflicting results among preclinical models and human physiological studies is that of adipose tissue oxygenation, where rodent models almost unanimously have shown the presence of hypoxia in the adipose tissue of obese animals while human studies have yielded conflicting results to date. Other issues which require further clarification before generalizing preclinical data in humans include adipose tissue browning, endocrine function and fibrosis. The aim of this mini-review is to synopsize similarities and differences between rodent models and humans, which should be taken into consideration in obesity studies.

Diabesity: a superadded effect contributing to worse total primary hip replacement operative outcomes for patients with diabetes and obesity

INTRODUCTION

Although the independent effects of diabetes mellitus and obesity on total hip replacement (THR) outcomes have been widely studied, their combined effect remains uncharacterised. This study aimed to assess the influence of diabesity on primary THR operative outcomes.

MATERIALS AND METHODS

A retrospective study was performed comparing the outcomes of patients with diabesity (diabetes mellitus and obesity [BMI ≥ 30]) with a control cohort after primary THR using an established arthroplasty database. Data were collected pre-operatively and 12 months post-operatively, including Oxford Hip Score (OHS), EuroQol 5-dimensions (EQ5D), post-operative satisfaction and complication rates.

RESULTS

2323 THRs were analysed, of which 94 (4%) had diabesity. Diabesity was independently associated with significantly worse OHS improvement post-operatively (- 1.85 points, 95% CI - 2.93 to - 0.76, p = 0.001). This reduction in addition to the independent effect of obesity (- 0.69 points, 95% CI - 1.18 to - 0.21, p = 0.005) resulted in an overall 2.54 point OHS reduction for patients with diabesity. Diabesity was not associated with EQ5D score change or post-operative satisfaction. Diabesity was independently associated with a worse pre-operative EQ5D score (-0.08 points, 95% CI -0.12 to -0.03, p = 0.002). When combining the associated risk of obesity (Odds Ratio (OR) 1.71, 95% CI 1.15-2.54, p = 0.008) with the superadded effect of diabesity (OR 2.37, 95% CI 1.19-4.71, p = 0.014) the rate of superficial wound infection post-operatively was significantly increased (OR 4.05, 95% CI 1.38-11.95). Obesity was associated with a significantly increased risk of deep infection (OR 3.67, 95% CI 1.55-8.68, p = 0.003), but no additive effect of diabetes was found.

CONCLUSIONS

Diabesity confers a superadded effect over established associations between THR outcomes and obesity and diabetes individually. Patients with diabesity experience worse improvement in hip-specific functional outcome, worse post-operative quality of life, and an increased risk of superficial and deep wound infection following THR.

CYP1A1, VEGFA and Adipokine Responses of Human Adipocytes Co-exposed to PCB126 and Hypoxia

It is increasingly recognized that hypoxia may develop in adipose tissue as its mass expands. Adipose tissue is also the main reservoir of lipophilic pollutants, including polychlorinated biphenyls (PCBs). Both hypoxia and PCBs have been shown to alter adipose tissue functions. The signaling pathways induced by hypoxia and pollutants may crosstalk, as they share a common transcription factor: aryl hydrocarbon receptor nuclear translocator (ARNT). Whether hypoxia and PCBs crosstalk and affect adipokine secretion in human adipocytes remains to be explored. Using primary human adipocytes acutely co-exposed to different levels of hypoxia (24 h) and PCB126 (48 h), we observed that hypoxia significantly inhibits the PCB126 induction of cytochrome P450 (CYP1A1) transcription in a dose-response manner, and that Acriflavine (ACF)—an HIF1α inhibitor—partially restores the PCB126 induction of CYP1A1 under hypoxia. On the other hand, exposure to PCB126 did not affect the transcription of the vascular endothelial growth factor-A (VEGFA) under hypoxia. Exposure to hypoxia increased leptin and interleukin-6 (IL-6), and decreased adiponectin levels dose-dependently, while PCB126 increased IL-6 and IL-8 secretion in a dose-dependent manner. Co-exposure to PCB126 and hypoxia did not alter the adipokine secretion pattern observed under hypoxia and PCB126 exposure alone. In conclusion, our results indicate that (1) hypoxia inhibits PCB126-induced CYP1A1 expression at least partly through ARNT-dependent means, suggesting that hypoxia could affect PCB metabolism and toxicity in adipose tissue, and (2) hypoxia and PCB126 affect leptin, adiponectin, IL-6 and IL-8 secretion differently, with no apparent crosstalk between the two factors.

Association between cardiometabolic risk factors and COVID-19 susceptibility, severity and mortality: a review

The novel coronavirus, which began spreading from China Wuhan and gradually spreaded to most countries, led to the announcement by the World Health Organization on March 11, 2020, as a new pandemic. The most important point presented by the World Health Organization about this disease is to better understand the risk factors that exacerbate the course of the disease and worsen its prognosis. Due to the high majority of cardio metabolic risk factors like obesity, hypertension, diabetes, and dyslipidemia among the population over 60 years old and higher, these cardio metabolic risk factors along with the age of these people could worsen the prognosis of the coronavirus disease of 2019 (COVID-19) and its mortality. In this study, we aimed to review the articles from the beginning of the pandemic on the impression of cardio metabolic risk factors on COVID-19 and the effectiveness of COVID-19 on how to manage these diseases. All the factors studied in this article, including hypertension, diabetes mellitus, dyslipidemia, and obesity exacerbate the course of Covid-19 disease by different mechanisms, and the inflammatory process caused by coronavirus can also create a vicious cycle in controlling these diseases for patients.

Obesity in COVID-19 era, implications for mechanisms, comorbidities, and prognosis: a review and meta-analysis

Background

Recent studies have shown that obesity is associated with the severity of coronavirus disease (COVID-19). We reviewed clinical studies to clarify the obesity relationship with COVID-19 severity, comorbidities, and discussing possible mechanisms.

Materials and methods

The electronic databases, including Web of Science, PubMed, Scopus, and Google Scholar, were searched and all studies conducted on COVID-19 and obesity were reviewed. All studies were independently screened by reviewers based on their titles and abstracts.

Results

Forty relevant articles were selected, and their full texts were reviewed. Obesity affects the respiratory and immune systems through various mechanisms. Cytokine and adipokine secretion from adipose tissue leads to a pro-inflammatory state in obese patients, predisposing them to thrombosis, incoordination of innate and adaptive immune responses, inadequate antibody response, and cytokine storm. Obese patients had a longer virus shedding. Obesity is associated with other comorbidities such as hypertension, cardiovascular diseases, diabetes mellitus, and vitamin D deficiency. Hospitalization, intensive care unit admission, mechanical ventilation, and even mortality in obese patients were higher than normal-weight patients. Obesity could alter the direction of severe COVID-19 symptoms to younger individuals. Reduced physical activity, unhealthy eating habits and, more stress and fear experienced during the COVID-19 pandemic may result in more weight gain and obesity.

Conclusions

Obesity should be considered as an independent risk factor for the severity of COVID-19. Paying more attention to preventing weight gain in obese patients with COVID-19 infection in early levels of disease is crucial during this pandemic.

Effect of Intraoperative Goal-Directed Fluid Management on Tissue Oxygen Tension in Obese Patients: a Randomized Controlled Trial

Background

Perioperative subcutaneous tissue oxygen tension (PsqO₂) is substantially reduced in obese surgical patients. Goal-directed fluid therapy optimizes cardiac performance and thus tissue perfusion and oxygen delivery. We therefore tested the hypothesis that intra- and postoperative PsqO₂ is significantly reduced in obese patients undergoing standard fluid management compared to goal-directed fluid administration.

Methods

We randomly assigned 60 obese patients (BMI ≥ 30 kg/m²) undergoing laparoscopic bariatric surgery to receive either esophageal Doppler-guided goal-directed fluid management or conventional fluid treatment. Our primary outcome parameter was intra- and postoperative PsqO₂ measured with a polarographic electrode in the subcutaneous tissue of the upper arm. A random effects linear regression model was used to analyze the effect of intervention.

Results

Overall, mean (± SD) PsqO₂ was significantly higher in obese patients receiving goal-directed therapy compared to conventional fluid therapy (65.8 ± 28.0 mmHg vs. 53.7 ± 21.7, respectively; repeated measures design adjusted difference: 13.0 mmHg [95% CI 2.3 to 23.7; p = 0.017]). No effect was seen intraoperatively (69.6 ± 27.9 mmHg vs. 61.4 ± 28.8, difference: 9.7 mmHg [95% CI -3.8 to 23.2; p = 0.160]); however, goal-directed fluid management improved PsqO₂ in the early postoperative phase (63.1 ± 27.9 mmHg vs. 48.4 ± 12.5, difference: 14.5 mmHg [95% CI 4.1 to 24.9; p = 0.006]). Intraoperative fluid requirements did not differ between the two groups.

Conclusions

Goal-directed fluid therapy improved subcutaneous tissue oxygenation in obese patients. This effect was more pronounced in the early postoperative period.

Clinical Trial Number and Registry

The study was registered at ClinicalTrials.gov (NCT 01052519).

Thoracoscopic radical surgery for a morbidly obese patient with early lung cancer after laparoscopic sleeve gastrectomy: a case report

Background

We experienced a case of early stage lung cancer involving a morbidly obese patient. Obesity is associated with a higher incidence of surgical complications. We examined the effectiveness of laparoscopic sleeve gastrectomy as a primary weight loss procedure in a morbidly obese patient who required oncological surgery.

Case presentation

A 64-year-old morbidly obese female with a body mass index of 43.5 kg/m² was referred to our hospital to undergo weight loss. A right-sided lung mass was found incidentally on computed tomography conducted in preparation for laparoscopic sleeve gastrectomy, which was performed prior to tumor surgery. As a result, weight loss was achieved within 2.5 months after the laparoscopic sleeve gastrectomy, and the patient’s type-2 diabetes, hypertension, and dyslipidemia, which are linked to obesity, were markedly ameliorated. After a quick intraoperative pathological inspection revealed that the tumor was malignant, thoracoscopic right lung superior lobe resection was performed safely.

Conclusions

Laparoscopic sleeve gastrectomy proved to be a powerful approach in a case in which a morbidly obese patient with early stage cancer needed to lose weight rapidly.

Oxygen: viral friend or foe?

The oxygen levels organ and tissue microenvironments vary depending on the distance of their vasculature from the left ventricle of the heart. For instance, the oxygen levels of lymph nodes and the spleen are significantly lower than that in atmospheric air. Cellular detection of oxygen and their response to low oxygen levels can exert a significant impact on virus infection. Generally, viruses that naturally infect well-oxygenated organs are less able to infect cells under hypoxic conditions. Conversely, viruses that infect organs under lower oxygen tensions thrive under hypoxic conditions. This suggests that in vitro experiments performed exclusively under atmospheric conditions ignores oxygen-induced modifications in both host and viral responses. Here, we review the mechanisms of how cells adapt to low oxygen tensions and its impact on viral infections. With growing evidence supporting the role of oxygen microenvironments in viral infections, this review highlights the importance of factoring oxygen concentrations into in vitro assay conditions. Bridging the gap between in vitro and in vivo oxygen tensions would allow for more physiologically representative insights into viral pathogenesis.

Oxygenation of adipose tissue: A human perspective

Obesity is a complex disorder of excessive adiposity, and is associated with adverse health effects such as cardiometabolic complications, which are to a large extent attributable to dysfunctional white adipose tissue. Adipose tissue dysfunction is characterized by adipocyte hypertrophy, impaired adipokine secretion, a chronic low‐grade inflammatory status, hormonal resistance and altered metabolic responses, together contributing to insulin resistance and related chronic diseases. Adipose tissue hypoxia, defined as a relative oxygen deficit, in obesity has been proposed as a potential contributor to adipose tissue dysfunction, but studies in humans have yielded conflicting results. Here, we will review the role of adipose tissue oxygenation in the pathophysiology of obesity‐related complications, with a specific focus on human studies. We will provide an overview of the determinants of adipose tissue oxygenation, as well as the role of adipose tissue oxygenation in glucose homeostasis, lipid metabolism and inflammation. Finally, we will discuss the putative effects of physiological and experimental hypoxia on adipose tissue biology and whole‐body metabolism in humans. We conclude that several lines of evidence suggest that alteration of adipose tissue oxygenation may impact metabolic homeostasis, thereby providing a novel strategy to combat chronic metabolic diseases in obese humans.

Randomized controlled trial of regional tissue oxygenation following goal-directed fluid therapy during laparoscopic colorectal surgery

BACKGROUND

A randomized, double-blinded controlled trial was performed to evaluate how perioperative goal-directed fluid therapy (GDFT) influences tissue oxygenation in laparoscopic colorectal surgery.

METHODS

A total of 74 patients undergoing elective laparoscopic colorectal surgery were treated with GDFT (G group) guided by stroke volume variation or conventional fluid therapy (C group). Forearm, crural, and cerebral tissue oxygen saturation (rSO₂) were simultaneously measured by near-infrared spectroscopy. Parameters of hemodynamics and rSO₂ were obtained at seven time points including before induction of anesthesia (T1), 5 min after trachea cannula (T2), 5, 60, and 120 min after pneumoperitoneum in the Trendeleburg position (T3, T4 and T5, respectively), after desufflation in the Trendeleburg position (T6), and at the end of the operation in a supine position (T7). The postoperative outcomes were recorded.

RESULTS

Compared to C group, intraoperatively, patients in the G group received more colloid (P<0.05). The stroke volume variation in G group at T5, T6 and T7 was significantly lower than that in C group (P<0.05). The cardiac index, forearm and crural rSO₂ in G group at T4, T5, T6 and T7 were significantly higher than those in C group (P<0.05). No significant differences were observed for the cerebral rSO₂ between the two groups (P > 0.05). The postoperative hospital stay and complications also showed no differences between these two groups.

CONCLUSIONS

Although the implementation of GDFT cannot increase cerebral rSO₂, the forearm and crural rSO₂ are improved during the laparoscopic colorectal surgery, which is helpful to reduce the risk of regional tissue hypoxia.

Body Mass Index does not affect intraoperative goal-directed fluid requirements

BACKGROUND

Perioperative normovolemia is a major determinant of tissue oxygen availability and postoperative outcome. Thus, adequate volume replacement therapy remains an essential part of perioperative management. Nevertheless, volume optimization in overweight and obese surgical patients with alterations in cardiovascular function, peripheral perfusion, and body composition remains challenging. We, therefore, tested the hypothesis that Body Mass Index (BMI) correlates with fluid requirements during goal-directed management. Furthermore, we evaluated subcutaneous tissue oxygen tension (PsqO2) as an indicator of intravascular volume status and peripheral perfusion.

METHODS

Ninety women, undergoing open gynecologic surgery, were assigned to three groups according to their BMI, (lean: BMI 18.5 to 24.9 kg/m2, overweight: BMI 25 to 29.9 kg/m2, obese: BMI>30 kg/m2). Esophageal Doppler monitoring guided intraoperative crystalloid administration. Tissue oxygen tension was measured with a polarographic electrode in the subcutaneous tissue of the upper arm and served as a secondary outcome parameter.

RESULTS

BMI and fluid requirements did not correlate (r=0.093, P=0.384). Total amounts of administered crystalloids were comparable. Lean patients received 2223±1811 mL in total, while overweight patients received 1866±1261 mL. Obese patients required 2416±1143 mL of total crystalloids (P=0.327). Intra- and postoperative PsqO2 did not differ significantly (97.3 vs. 86.8 vs. 79.6 mmHg, P=0.06 and 74.5 vs. 83 vs. 81.5 mmHg, P=0.63, respectively).

CONCLUSIONS

BMI did not affect intraoperative fluid requirements. Doppler-guided intravascular volume optimization was associated with well-maintained subcutaneous tissue oxygen availability in all BMI groups.

Body mass index and the risk of deep surgical site infection following posterior cervical instrumented fusion

BACKGROUND

Surgical site infection (SSI) following spine surgery is associated with increased morbidity, reoperation rates, hospital readmissions, and cost. The incidence of SSI following posterior cervical spine surgery is higher than anterior cervical spine surgery, with rates from 4.5% to 18%. It is well documented that higher body mass index (BMI) is associated with increased risk of SSI after spine surgery. There are only a few studies that examine the correlation of BMI and SSI after posterior cervical instrumented fusion (PCIF) using national databases, however, none that compare trauma and nontraumatic patients.

PURPOSE

The purpose of this study is to determine the odds of developing SSI with increasing BMI after PCIF, and to determine the risk of SSI in both trauma and nontraumatic adult patients.

STUDY DESIGN

This is a retrospective cohort study of a prospective surgical database collected at one academic institution.

PATIENT SAMPLE

The patient sample is from a prospectively collected surgical registry from one institution, which includes patients who underwent PCIF from April 2011 to October 2017.

OUTCOME MEASURES

A SSI that required return to the operating room for surgical debridement.

METHODS

This is a retrospective cohort study using a prospectively collected database of all spine surgeries performed at our institution from April 2011 to October 2017. We identified 1,406 patients, who underwent PCIF for both traumatic injuries and nontraumatic pathologies using International Classification of Diseases 9 and 10 procedural codes. Thirty-day readmission data were obtained. Patient's demographics, BMI, presence of diabetes, preoperative diagnosis, and surgical procedures performed were identified. Using logistic regression analysis, the risk of SSI associated with every one-unit increase in BMI was determined. This study received no funding. All the authors in this study report no conflict of interests relevant to this study.

RESULTS

Of the 1,406 patients identified, 1,143 met our inclusion criteria. Of those patients, 688 had PCIF for traumatic injuries and 454 for nontraumatic pathologies. The incidence of SSI for all patients, who underwent PCIF was 3.9%. There was no significant difference in the rate of SSI between our trauma group and nontraumatic group. There was a higher rate of infection in patients, who were diabetic and with BMI≥30 kg/m². The presence of both diabetes and BMI≥30 kg/m² had an added effect on the risk of developing SSI in all patients, who underwent PCIF. Additionally, logistic regression analysis showed that there was a positive difference measure between BMI and SSI. Our results demonstrate that for one-unit increase in BMI, the odds of having a SSI is 1.048 (95% CI: 1.007-1.092, p=.023).

CONCLUSIONS

Our study demonstrates that our rate of SSI after PCIF is within the range of what is cited in the literature. Interestingly, we did not see a statistically significant difference in the rate of infection between our trauma and nontrauma group. Overall, diabetes and elevated BMI are associated with increased risk of SSI in all patients, who underwent PCIF with even a higher risk in patient, who are both diabetic and obese. Obese patients should be counseled on elevated SSI risk after PCIF, and those with diabetes should be medically optimized before and after surgery when possible to minimize SSI.

Prevention of Infection in Foot and Ankle Surgery

The literature for prevention of surgical infection related primarily to foot and ankle surgery is sparse, with most attention on total joint replacement and abdominal surgery. Attention should be paid to preoperative, intraoperative, and postoperative elements, which can have an effect on the development of postoperative infection. Although antibiotic prophylaxis typically is discussed in isolation, inclusion of this step into the process enhances the overall evaluation of surgery with respect to infection. This evolution provides for better patient outcomes and decreases the likelihood of an infection incurred after foot and ankle surgery.

In vitro profiling of volatile organic compounds released by Simpson-Golabi-Behmel syndrome adipocytes

Breath analysis offers a non-invasive and rapid diagnostic method for detecting various volatile organic compounds that could be indicators for different diseases, particularly metabolic disorders including type 2 diabetes mellitus. The development of type 2 diabetes mellitus is closely linked to metabolic dysfunction of adipose tissue and adipocytes. However, the VOC profile of human adipocytes has not yet been investigated. Gas chromatography with mass spectrometric detection and head-space needle trap extraction (two-bed Carbopack X/Carboxen 1000 needle traps) were applied to profile VOCs produced and metabolised by human Simpson Golabi Behmel Syndrome adipocytes. In total, sixteen compounds were identified to be related to the metabolism of the cells. Four sulphur compounds (carbon disulphide, dimethyl sulphide, ethyl methyl sulphide and dimethyl disulphide), three heterocyclic compounds (2-ethylfuran, 2-methyl-5-(methyl-thio)-furan, and 2-pentylfuran), two ketones (acetone and 2-pentanone), two hydrocarbons (isoprene and n-heptane) and one ester (ethyl acetate) were produced, and four aldehydes (2-methyl-propanal, butanal, pentanal and hexanal) were found to be consumed by the cells of interest. This study presents the first profile of VOCs formed by human adipocytes, which may reflect the activity of the adipose tissue enzymes and provide evidence of their active role in metabolic regulation. Our data also suggest that a previously reported increase of isoprene and sulphur compounds in diabetic patients may be explained by their production by adipocytes. Moreover, the unique features of this profile, including a high emission of dimethyl sulphide and the production of furan-containing VOCs, increase our knowledge about metabolism in adipose tissue and provide diagnostic potential for future applications.

Effects training in hypoxia on cardiometabolic parameters in obese people: A systematic review of randomized controlled trial

Objective

The aim of the present review is to evaluate effects of intermittent hypoxia and exercise therapy in cardiometabolic parameters on adult obese people.

Database

Three well-known databases were selected: EMBASE, MEDLINE and Web of Science. Studies selection: Inclusion criteria were: (a) human healthy overweight or obese adults, (b) study randomized controlled trial, (c) original experimental study, (d) English languages and (e) therapy with intermittent hypoxia and exercise.

Design

The assessment of the methodological quality of each study was based upon the risk of bias (PEDro scale) and level of evidence (CBO Guidelines). Data extraction: five articles clearly met inclusion criteria and were reviewed to data extraction.

Results

In the hypoxia groups, weight, body mass index, waist circumference, waist–hip ratio, fat mass and lean mass improved in at least two studies in comparison with the baseline. Systolic blood pressure improved in one study. The lipid profile and the aerobic capacity were not reduced significantly.

Conclusions

Results suggest that combined hypoxia with exercise may help to improve cardiometabolic parameters in obese people.

Associations of Obesity With Incident Hospitalization Related to Peripheral Artery Disease and Critical Limb Ischemia in the ARIC Study

Background We conducted an analysis of data from the ARIC (Atherosclerosis Risk in Communities) study to assess the independent association of obesity with peripheral artery disease ( PAD ) and critical limb ischemia ( CLI ). Methods and Results All black and white ARIC participants without prevalent PAD at baseline (1987-1989) were included. We used Cox proportional hazards models adjusting for potential confounders and then potential mediators to quantify the association between body mass index ( BMI ) and incident hospitalizations related to PAD without CLI and with CLI through 2013. Our analysis included 13 988 men and women followed for a median of 24 years. Incident PAD without CLI and PAD with CLI occurred in 373 and 201 participants, respectively. After adjusting for potential confounders, higher BMI at baseline was associated with increased risk of PAD without CLI when BMI was modeled continuously (hazard ratio per 1- SD increment in BMI: 1.23; 95% confidence interval, 1.11-1.37) and with PAD with CLI regardless of whether BMI was modeled categorically ( P<0.05) or continuously (hazard ratio per 1- SD increment in BMI: 1.51; 95% confidence interval, 1.34-1.69). The associations of BMI with PAD without CLI and with CLI were attenuated after further accounting for potential mediators but remained significant for PAD with CLI when BMI was linearly modeled (hazard ratio per 1- SD increment in BMI: 1.19; 95% confidence interval, 1.04-1.36). The positive association between BMI and PAD with CLI was stronger than the association between BMI and PAD without CLI for all models ( P<0.001). Conclusions In the general population, BMI is positively associated with incident hospitalized PAD after adjusting for potential confounders, particularly its most severe form of CLI . Maintaining an optimal weight, in addition to controlling other cardiovascular risk factors, may play a role in reducing risk of PAD with CLI .

Polyphenols and their effects on diabetes management: A review

Background: Type 2 diabetes is a growing public health problem and is associated with increased morbidity and mortality. The worldwide prevalence of type 2 diabetes is rising. Polyphenols, such as flavonoids, phenolic acid, and stilbens, are a large and heterogeneous group of phytochemicals in plant-based foods. In this review, we aimed at assessing the studies on polyphenols and diabetes management. Methods: A literature search in the PubMed, EMBASE, Scopus, and ISI Web of Science databases was conducted to identify relevant studies published from 1986 to Jan 2017. Results: Several animal models and a limited number of human studies have revealed that polyphenols decrease hyperglycemia and improve acute insulin secretion and insulin sensitivity. The possible mechanisms include decrease in glucose absorption in the intestine, inhibition of carbohydrates digestion, stimulation of insulin secretion, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in insulin-sensitive tissues, modulation of intracellular signaling pathways, and gene expression. Conclusion: Growing evidence indicates that various dietary polyphenols may influence blood glucose at different levels and may also help control and prevent diabetes complication. However, we still need more clinical trials to determine the effects of polyphenols- rich foods, their effective dose, and mechanisms of their effects in managing diabetes.

Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations

BACKGROUND

During the last two decades, an increasing number of bariatric surgical procedures have been performed worldwide. There is no consensus regarding optimal perioperative care in bariatric surgery. This review aims to present such a consensus and to provide graded recommendations for elements in an evidence-based "enhanced" perioperative protocol.

METHODS

The English-language literature between January 1966 and January 2015 was searched, with particular attention paid to meta-analyses, randomised controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded. After critical appraisal of these studies, the group of authors reached a consensus recommendation.

RESULTS

Although for some elements, recommendations are extrapolated from non-bariatric settings (mainly colorectal), most recommendations are based on good-quality trials or meta-analyses of good-quality trials.

CONCLUSIONS

A comprehensive evidence-based consensus was reached and is presented in this review by the enhanced recovery after surgery (ERAS) Society. The guidelines were endorsed by the International Association for Surgical Metabolism and Nutrition (IASMEN) and based on the evidence available in the literature for each of the elements of the multimodal perioperative care pathway for patients undergoing bariatric surgery.

Nutrient Deficiencies Are Common Prior to Bariatric Surgery

Obesity, defined as a body mass index >30 kg/m², is a growing worldwide epidemic currently effecting 1 in 10 adults, with rates as high as 40% in the United States. The only proven long-term treatment of severe obesity on a population level is surgical modification of the gastrointestinal anatomy to induce weight loss, termed bariatric surgery. With adequate physician guidance and appropriate candidate criteria, bariatric surgery is an option for effective long-term treatment of obesity and its related comorbidities. Complications of bariatric surgery can be seen in patients who are not compliant to the recommended lifestyle and dietary changes required following bariatric surgery, including nausea, vomiting, dumping syndrome, acid reflux, and nutrition deficiencies. Despite caloric density, the diet of patients prior to bariatric surgery is often of poor nutrition quality and does not meet recommended dietary guidelines for micronutrient intake, making this an at-risk population for micronutrient malnutrition. Currently, improvements are needed in standardization of nutrition assessment as well as micronutrient cutoffs for deficiency and insufficiency. In the meantime, utilizing our current tools to conduct nutrition assessment at baseline and implement supplementation where necessary may improve the nutrition status of patients undergoing bariatric surgery, both before and after surgery, which may improve their surgical outcomes.

Risk factors for surgical site infection after posterior cervical spine surgery: an analysis of 5,441 patients from the ACS NSQIP 2005-2012

BACKGROUND CONTEXT

The incidence of surgical site infection (SSI) following posterior cervical surgery has been reported as high as 18% in the literature. Few large studies have specifically examined posterior cervical procedures.

PURPOSE

The study aims to examine the incidence, timing, and risk factors for SSI following posterior cervical surgery.

DESIGN

This is a retrospective cohort study of prospectively collected data in a national surgical outcomes database.

PATIENT SAMPLE

The sample includes patients who underwent posterior cervical spine surgery between 2005 and 2012 identified in the American College of Surgeons National Surgical Quality Improvement Project (ACS NSQIP) Participant Use Data File.

OUTCOME MEASURES

The 30-day rate of postoperative SSI, timing of diagnosis, and associated risk factors were determined.

METHODS

The ACS NSQIP was used to identify 5,441 patients who underwent posterior cervical spine surgery by Current Procedural Terminology codes from 2005 to 2012. Thirty-day readmission data were obtained for 2011-2012. The incidence and timing of SSI were determined. Multivariable logistic regression analysis was then performed to identify significant risk factors.

RESULTS

Of the 5,441 patients identified as having undergone posterior cervical surgery, 3,724 had a posterior cervical decompression, 1,310 had a posterior cervical fusion, and 407 underwent cervical laminoplasty. Surgical site infection within 30 days was identified in 160 patients (2.94%), with 80 of those cases being superficial SSI. There was no significant difference in SSI rate among the three procedure groups. The average time for diagnosis of SSI was over 2 weeks. In 2011-2012, 36.9% of patients with SSI were readmitted within 30 days. Several significant predictors of SSI were identified in univariate analysis, including body mass index (BMI) >35, chronic steroid use, albumin <3, hematocrit <33, platelets <100, higher American Society of Anesthesiologists class, longer operative time, and longer hospital admission. Independent risk factors, including BMI >35 (odds ratio [OR]=1.78, p=.003), chronic steroid use (OR=1.73, p=.049), and operative time >197 minutes (OR=2.08, p=.005), were identified in multivariable analysis.

CONCLUSIONS

Optimization of preoperative nutritional status, serum blood cell counts, and operative efficiency may lead to a reduction in SSI rates. Obese patients and patients on chronic steroid therapy should be counseled on elevated SSI risk.

Hyperlactatemia in type 2 diabetes: Can physical training help?

Type 2 diabetic patients often exhibit hyperlactatemia in association with a reduced aerobic-oxidative capacity and a restricted lactate transport. Studies suggest a link between increased lactate levels and the manifestation and progression of insulin resistance. However, the specificities of molecular mechanisms remain unclear, and it is not entirely clear whether elevated lactate levels are a cause or consequence of type 2 diabetes. This review focuses on lactate as a key molecule in diabetes and provides an overview of how regular physical activity can be helpful in normalizing elevated lactate levels in type 2 diabetic patients. Physical training may reduce lactate production and reinforce lactate transport and clearance among this particular patient group. We emphasize the crucial role physical training plays in the therapy of type 2 diabetes due to evidence that pharmacological treatment with metformin, which is commonly used in the first-line therapy of type 2 diabetes, does not help reducing lactate levels.

Hypoxia induces a HIF-1α dependent signaling cascade to make a complex metabolic switch in SGBS-adipocytes

To elucidate the complex impact of hypoxia on adipose tissue, resulting in biased metabolism, insulin resistance and finally diabetes we used mature adipocytes derived from a Simpson-Golabi-Behmel syndrome patient for microarray analysis. We found a significantly increased transcription rate of genes involved in glycolysis and a striking association between the pattern of upregulated genes and disease biomarkers for diabetes mellitus and insulin resistance. Although their upregulation turned out to be HIF-1α-dependent, we identified further transcription factors mainly AP-1 components to play also an important role in hypoxia response. Analyzing the regulatory network of mentioned transcription factors and glycolysis targets we revealed a clear hint for directing glycolysis to glutathione and glycogen synthesis. This metabolic switch in adipocytes enables the cell to prevent oxidative damage in the short term but might induce lipogenesis and establish systemic metabolic disorders in the long run.

The relationship between serum hypoxia-inducible factor 1α and coronary artery calcification in asymptomatic type 2 diabetic patients

Background

Hypoxia-inducible factor 1 (HIF-1), a master regulator of oxygen homeostasis, is a heterodimer consisting of HIF-1α and HIF-1β subunits, and is implicated in calcification of cartilage and vasculature. The goal of this study was to determine the relationship between serum HIF-1α with coronary artery calcification (CAC) in patients with type 2 diabetes.

Methods

The subjects were 405 (262 males, 143 females, age 51.3 ± 6.4 years) asymptomatic patients with type 2 diabetes mellitus. Serum HIF-1α and interleukin-6 (IL-6) levels were measured by ELISA. CAC scores were assessed by a 320-slice CT scanner. The subjects were divided into 4 quartiles depending on serum HIF-1α levels.

Results

Average serum HIF-1α was 184.4 ± 66.7 pg/ml. Among patients with higher CAC scores, HIF-1α levels were also significantly increased (p <0.001). HIF-1α levels positively correlated with CRP, IL-6, UKPDS risk score, HbA1c, FBG, and CACS, but did not correlate with diabetes duration, age, and LDL. According to the multivariate analysis, HIF-1α levels significantly and independently predict the presence of CAC. ROC curve analysis showed that the serum HIF-1α level can predict the extent of CAC, but the specificity was lower than the traditional risk factors UKPDS and HbA1c.

Conclusion

As a marker of hypoxia, serum HIF-1α level may be an independent risk factor for the presence of CAC. These findings indicate that elevated serum HIF-1α may be involved in vascular calcification in patients with type 2 diabetes mellitus.

Hypoxia induced changes of SePP1 expression in rat preadipocytes and its impact on vascular fibroblasts

Human adipose tissues secret a lot of cytokines involved in physiological and pathological activities. Inflammation around blood vessels is positively related to the severity of atherosclerosis. This study was to investigate the impact of adipokine SePP1 on vascular fibroblasts (VF) under a hypoxia condition might provide new evidence and methods for treatment of atherosclerosis. The mRNA and protein expression of IL-6, MCP-1 and SePP1 were detected in preadipocytes under normoxic (21% O2) and hyperoxic (4% O2) conditions, and the impact of IL-6, MCP-1 and SePP1 on VF was investigated. The preadipocytes were cultured under normoxic and hypoxic conditions. Then, the cell growth, and the mRNA and protein expression of inflammatory cytokines (IL-6, MCP-1 and SePP1) were detected. The VF were cultured in the medium collected from preadipocytes maintained under hypoxic and normoxic conditions, and the phenotypes, migration and type I collagen protein of VF were determined. Results showed that under the hypoxic condition, the proliferation of preadipocytes increased significantly (P<0.05), and the mRNA and protein expression of IL-6 and MCP-1 elevated markedly (P<0.05). However, the SePP1 expression reduced dramatically (P<0.05). After co-culture with VF, the VF transformed into myofibroblasts, accompanied by increased migration and elevated type I collagen expression (P<0.05). Thus, hypoxia may accumulate visceral fat and induce inflammatory state of preadipocytes, with reduced SePP1 expression, which might be involved in the occurrence and development of atherosclerosis.

Adipose tissue oxygenation: Effects on metabolic function

With the increasing prevalence of obesity there is a concomitant increase in white adipose tissue dysfunction, with the tissue moving toward a proinflammatory phenotype. Adipose tissue hypoxia has been proposed as a key underlying mechanism triggering tissue dysfunction but data from human, in vivo studies, to support this hypothesis is limited. Human adipose tissue oxygenation has been investigated by direct assessment of tissue oxygen tension (pO2) or by expression of hypoxia-sensitive genes/protein in lean and obese subjects but findings are inconsistent. An obvious read-out of hypoxia is the effect on intermediary metabolism, and we have investigated the functional consequences, in terms of a "metabolic signature" of human adipose tissue hypoxia in vivo. Here, we discuss the different approaches used and the importance of integrative physiological techniques to try and elucidate what defines adipose tissue hypoxia in humans.

Hexosamine biosynthesis is a possible mechanism underlying hypoxia's effects on lipid metabolism in human adipocytes

INTRODUCTION

Hypoxia regulates adipocyte metabolism. Hexosamine biosynthesis is implicated in murine 3T3L1 adipocyte differentiation and is a possible underlying mechanism for hypoxia's effects on adipocyte metabolism.

METHODS

Lipid metabolism was studied in human visceral and subcutaneous adipocytes in in vitro hypoxic culture with adipophilic staining, glycerol release, and palmitate oxidation assays. Gene expression and hexosamine biosynthesis activation was studied with QRTPCR, immunofluorescence microscopy, and Western blotting.

RESULTS

Hypoxia inhibits lipogenesis and induces basal lipolysis in visceral and subcutaneous human adipocytes. Hypoxia induces fatty acid oxidation in visceral adipocytes but had no effect on fatty acid oxidation in subcutaneous adipocytes. Hypoxia inhibits hexosamine biosynthesis in adipocytes. Inhibition of hexosamine biosynthesis with azaserine attenuates lipogenesis and induces lipolysis in adipocytes in normoxic conditions, while promotion of hexosamine biosynthesis with glucosamine in hypoxic conditions slightly increases lipogenesis.

CONCLUSIONS

Hypoxia's net effect on human adipocyte lipid metabolism would be expected to impair adipocyte buffering capacity and contribute to systemic lipotoxicity. Our data suggest that hypoxia may mediate its effects on lipogenesis and lipolysis through inhibition of hexosamine biosynthesis. Hexosamine biosynthesis represents a target for manipulation of adipocyte metabolism.

Challenges in the surgical management of spine trauma in the morbidly obese patient: a case series

Object

The treatment of morbidly obese individuals with spine trauma presents unique challenges to spine surgeons and trauma staff. This study aims to increase awareness of current limitations in the surgical management of spine trauma in morbidly obese individuals, and to illustrate practical solutions.

Methods

Six morbidly obese patients were treated surgically for spine trauma over a 2-year period at a single trauma center in Australia. All patients were involved in high-speed motor vehicle accidents and had multisystem injuries. All weighed in excess of 265 pounds (120 kg) with a body mass index ≥ 40 (range 47.8–67.1). Cases were selected according to the considerable challenges they presented in all aspects of their management.

Results

Best medical and surgical care may be compromised and outcome adversely affected in morbidly obese patients with spine trauma. The time taken to perform all aspects of care is usually extended, often by many hours. Customized orthotics may be required. Imaging quality is often compromised and patients may not fit into scanners. Surgical challenges include patient positioning, surgical access, confirmation of the anatomical level, and obtaining adequate instrument length. Postoperative nursing care, wound healing, and venous thromboembolism prophylaxis are also significant issues.

Conclusions

Management pathways and hospital guidelines should be developed to optimize the treatment of morbidly obese patients, but innovative solutions may be required for individual cases.

Metabolic signatures of human adipose tissue hypoxia in obesity

Adipose tissue (AT) hypoxia has been proposed as the cause of obesity-related AT dysfunction, moving the tissue toward a proinflammatory phenotype. In humans, AT oxygenation has been assessed by expression of hypoxia-sensitive genes or direct assessment of O₂ tension; the obvious read out of hypoxia, effects on intermediary metabolism, has not been investigated. We used tissue-specific venous catheterization of subcutaneous abdominal AT in humans to investigate oxygen-related metabolic processes, searching for metabolic signatures relating to hypoxia in obesity. O₂ delivery to AT was reduced in obesity (P < 0.05). However, O₂ consumption was low (<30% of resting forearm skeletal muscle [SM], P < 0.001); this was not related to obesity. AT primarily oxidized glucose, as demonstrated by a respiratory quotient close to 1.0 (higher than SM, P < 0.05). AT was a net producer of lactate, but there was an inverse relationship in venous outflow between lactate-to-pyruvate ratio (a marker of cytosolic redox state) and BMI, suggesting that AT is glycolytic but obese AT is not hypoxic. Although delivery of O₂ to the obese AT is reduced, O₂ consumption is low, and metabolic signatures of human AT do not support the notion of a hypoxic state in obesity.

Reducing surgical site infection in arthroplasty of the lower limb: A multi-disciplinary approach

Objectives

To review the current best surgical practice and detail a multi-disciplinary approach that could further reduce joint replacement infection.

Methods

Review of relevant literature indexed in PubMed.

Results

Surgical site infection is a major complication following arthroplasty. Despite its rarity in contemporary orthopaedic practice, it remains difficult to treat and is costly in terms of both patient morbidity and long-term health care resources.

Conclusions

Emphasis on education of patients and all members of the health-care team and raising awareness in how to participate in preventative efforts is imperative.

Resveratrol has inhibitory effects on the hypoxia-induced inflammation and angiogenesis in human adipose tissue in vitro

Hypoxia modulates the production of proteins involved in e.g. inflammation, angiogenesis and glucose utilization and hypoxia may therefore be an important factor underlying adipose tissue dysfunction in obesity. Resveratrol (RSV) is a natural polyphenolic compound and has been shown to have powerful anti-inflammatory effects and beneficial effects on several obesity-related complications. Thus, in the present study we investigated whether RSV has effects on hypoxic markers (GLUT-1, VEGF), hypoxia-induced key markers of inflammation (IL8, IL6), and leptin in human adipose tissue in vitro. Hypoxia was induced by incubating human adipose tissue fragments with 1% O2 for 24h as compared to 21% O2 The gene expressions were investigated by RT-PCR and protein release by Elisa. Hypoxia increases the expression of glucose transporter-1 (GLUT-1) (19-fold, p<0.001), vascular endothelial growth factor (VEGF) (10-fold, p<0.05), interleukin-8 (IL8) (8-fold, p<0.05), interleukin-6 (IL6) (5-fold, p<0.05) and leptin (9-fold). The protein levels of VEGF released to the medium was increased (8-fold, p<0.01) by hypoxia. RSV dose-dependently inhibited several of these hypoxia-induced expressions and at a concentration of 50 μM RSV almost completely inhibited the hypoxic responses at the above mentioned gene expression levels (p<0.05-p<0.001) and significantly attenuated the hypoxia-induced protein releases by 50-60%. These results demonstrate that hypoxia induces extensive changes in human adipose tissue in the expression and release of inflammation and angiogenesis-related adipokines. In addition the inhibition of hypoxia-mediated inflammation and angiogenesis might represent a novel mechanism of RSV in preventing obesity-related pathologies.

Anesthetic implications of obesity in the surgical patient

The obese patient presents many challenges to both anesthesiologist and surgeon. A good understanding of the pathophysiologic effects of obesity and its anesthetic implications in the surgical setting is critical. The anesthesiologist must recognize increased risks and comorbidities inherent to the obese patient and manage accordingly, optimizing multisystem function in the perioperative period that leads to successful outcomes. Addressed from an organ systems approach, the purpose of this review is to provide surgical specialists with an overview of the anesthetic considerations of obesity. Minimally invasive surgery for the obese patient affords improved analgesia, postoperative pulmonary function, and shorter recovery times at the expense of a more challenging intraoperative anesthetic course. The physiologic effects of laparoscopy are discussed in detail. Although laparoscopy's physiologic effects on various organ systems are well recognized, techniques provide means for compensation and reversing such effects, thereby preserving good patient outcomes.

Epidemiology and outcomes associated with surgical site infection following bariatric surgery

BACKGROUND

Surgical site infection (SSI) is a frequent problem complicating bariatric surgery. However, the potential risk factors, risk stratification, and outcomes of SSIs in this patient population remain poorly defined. The aim of this prospective case-control study was to characterize better the risk factors and to improve risk stratification for SSIs following bariatric surgery.

METHODS

Patients studied had SSI following Roux-en-Y gastric bypass surgery (RYGBS) between November 2006 and March 2009 at Harper University Hospital and were each matched with 3 controls based on type of operative procedure, surgeon, and year of surgery. Thirty-day outcomes included mortality, hospital readmissions, outpatient procedures, and emergency room visits. A scoring system (BULCS score) was compared with the National Nosocomial Infections Surveillance system risk index using logistic regression.

RESULTS

In multivariate analysis, duration of surgery (odds ratio [OR], 3.3; 95% confidence interval [CI]: 1.62-6.74), diagnosis of bipolar disorder (OR, 3.341; 95% CI: 1.0-12.27), use of prophylactic antibiotics other than cefazolin (OR, 4.2; 95% CI: 1.47-11.69), and sleep apnea (OR, 1.8; 95% CI: 1.05-2.97) were significantly associated with SSI. Patients with SSI were more likely to have return emergency visits (OR, 4.96; 95% CI: 2.9-8.48), readmission (OR, 6.53; 95% CI: 3.44-12.42), and outpatient procedures following surgery (OR, 4.75; 95% CI: 1.32-17.14) than were controls without SSI. The BULCS score was a stronger predictor of SSI than the National Nosocomial Infections Surveillance system (C-statistic, -0.62 vs 0.55, respectively).

CONCLUSION

SSI following bariatric surgery was associated with receipt of antibiotic prophylaxis other than cefazolin and comorbid conditions including sleep apnea and bipolar disorder. The BULCS score performed favorably as a predictor and risk adjuster for SSI following bariatric surgery. SSI was associated with increased health care resource utilization.

Metabolic consequences of high-fat diet are attenuated by suppression of HIF-1α

Obesity is associated with tissue hypoxia and the up-regulation of hypoxia inducible factor 1 alpha (HIF-1α). Prior studies in transgenic mice have shown that HIF-1α plays a role in the metabolic dysfunction associated with obesity. Therefore, we hypothesized that, after the development of diet-induced obesity (DIO), metabolic function could be improved by administration of HIF-1α antisense oligonucleotides (ASO). DIO mice were treated with HIF-1α ASO or with control ASO for 8 weeks and compared with an untreated group. We found that HIF-1α ASO markedly suppressed Hif-1α gene expression in adipose tissue and the liver. HIF-1α ASO administration induced weight loss. Final body weight was 41.6±1.4 g in the HIF-1α ASO group vs 46.7±0.9 g in the control ASO group and 47.9±0.8 g in untreated mice (p<0.001). HIF-1α ASO increased energy expenditure (13.3±0.6 vs 12±0.1 and 11.9±0.4 kcal/kg/hr, respectively, p<0.001) and decreased the respiratory exchange ratio (0.71±0.01 vs 0.75±0.01 and 0.76±0.01, respectively, p<0.001), which suggested switching metabolism to fat oxidation. In contrast, HIF-1a ASO had no effect on food intake or activity. HIF-1α ASO treatment decreased fasting blood glucose (195.5±8.4 mg/dl vs 239±7.8 mg/dl in the control ASO group and 222±8.2 mg/dl in untreated mice, p<0.01), plasma insulin, hepatic glucose output, and liver fat content. These findings demonstrate that the metabolic consequences of DIO are attenuated by HIF-1α ASO treatment.

Phytochemicals and their impact on adipose tissue inflammation and diabetes

Type 2 diabetes mellitus is an inflammatory disease and the mechanisms that underlie this disease, although still incompletely understood, take place in the adipose tissue of obese subjects. Concurrently, the prevalence of obesity caused by Western diet's excessive energy intake and the lack of exercise escalates, and is believed to be causative for the chronic inflammatory state in adipose tissue. Overnutrition itself as an overload of energy may induce the adipocytes to secrete chemokines activating and attracting immune cells to adipose tissue. But also inflammation-mediating food ingredients like saturated fatty acids are believed to directly initiate the inflammatory cascade. In addition, hypoxia in adipose tissue as a direct consequence of obesity, and its effect on gene expression in adipocytes and surrounding cells in fat tissue of obese subjects appears to play a central role in this inflammatory response too. In contrast, revisiting diet all over the world, there are also some natural food products and beverages which are associated with curative effects on human health. Several natural compounds known as spices such as curcumin, capsaicin, and gingerol, or secondary plant metabolites catechin, resveratrol, genistein, and quercetin have been reported to provide an improved health status to their consumers, especially with regard to diabetes, and therefore have been investigated for their anti-inflammatory effect. In this review, we will give an overview about these phytochemicals and their role to interfere with inflammatory cascades in adipose tissue and their potential for fighting against inflammatory diseases like diabetes as investigated in vivo.

Obesity and symptomatic osteoarthritis of the knee

Given the growing prevalence of obesity around the world and its association with osteoarthritis of the knee, orthopaedic surgeons need to be familiar with the management of the obese patient with degenerative knee pain. The precise mechanism by which obesity leads to osteoarthritis remains unknown, but is likely to be due to a combination of mechanical, humoral and genetic factors. Weight loss has clear medical benefits for the obese patient and seems to be a logical way of relieving joint pain associated with degenerative arthritis. There are a variety of ways in which this may be done including diet and exercise, and treatment with drugs and bariatric surgery. Whether substantial weight loss can delay or even reverse the symptoms associated with osteoarthritis remains to be seen. Surgery for osteoarthritis in the obese patient can be technically more challenging and carries a risk of additional complications. Substantial weight loss before undertaking total knee replacement is advisable. More prospective studies that evaluate the effect of significant weight loss on the evolution of symptomatic osteoarthritis of the knee are needed so that orthopaedic surgeons can treat this patient group appropriately.

Identification of hypoxia-induced genes in human SGBS adipocytes by microarray analysis

Hypoxia in adipose tissue is suggested to be involved in the development of a chronic mild inflammation, which in obesity can further lead to insulin resistance. The effect of hypoxia on gene expression in adipocytes appears to play a central role in this inflammatory response observed in obesity. However, the global impact of hypoxia on transcriptional changes in human adipocytes is unclear. Therefore, we compared gene expression profiles of human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes under normoxic or hypoxic conditions to detect hypoxia-responsive genes in adipocytes by using whole human genome microarrays. Microarray analysis showed more than 500 significantly differentially regulated mRNAs after incubation of the cells under low oxygen levels. To gain further insight into the biological processes, hypoxia-regulated genes after 16 hours of hypoxia were classified according to their function. We identified an enrichment of genes involved in important biological processes such as glycolysis, response to hypoxia, regulation of cellular component movement, response to nutrient levels, regulation of cell migration, and transcription regulator activity. Real-time PCR confirmed eight genes to be consistently upregulated in response to 3, 6 and 16 hours of hypoxia. For adipocytes the hypoxia-induced regulation of these genes is shown here for the first time. Moreover in six of these eight genes we identified HIF response elements in the proximal promoters, specific for the HIF transcription factor family members HIF1A and HIF2A. In the present study, we demonstrated that hypoxia has an extensive effect on gene expression of SGBS adipocytes. In addition, the identified hypoxia-regulated genes are likely involved in the regulation of obesity, the incidence of type 2 diabetes, and the metabolic syndrome.

Effects of different acute hypoxic regimens on tissue oxygen profiles and metabolic outcomes

Obstructive sleep apnea (OSA) causes intermittent hypoxia (IH) during sleep. Both obesity and OSA are associated with insulin resistance and systemic inflammation, which may be attributable to tissue hypoxia. We hypothesized that a pattern of hypoxic exposure determines both oxygen profiles in peripheral tissues and systemic metabolic outcomes, and that obesity has a modifying effect. Lean and obese C57BL6 mice were exposed to 12 h of intermittent hypoxia 60 times/h (IH60) [inspired O₂ fraction (Fi(O₂)) 21-5%, 60/h], IH 12 times/h (Fi(O₂) 5% for 15 s, 12/h), sustained hypoxia (SH; Fi(O₂) 10%), or normoxia while fasting. Tissue oxygen partial pressure (Pti(O₂)) in liver, skeletal muscle and epididymal fat, plasma leptin, adiponectin, insulin, blood glucose, and adipose tumor necrosis factor-α (TNF-α) were measured. In lean mice, IH60 caused oxygen swings in the liver, whereas fluctuations of Pti(O₂) were attenuated in muscle and abolished in fat. In obese mice, baseline liver Pti(O₂) was lower than in lean mice, whereas muscle and fat Pti(O₂) did not differ. During IH, Pti(O₂) was similar in obese and lean mice. All hypoxic regimens caused insulin resistance. In lean mice, hypoxia significantly increased leptin, especially during SH (44-fold); IH60, but not SH, induced a 2.5- to 3-fold increase in TNF-α secretion by fat. Obesity was associated with striking increases in leptin and TNF-α, which overwhelmed effects of hypoxia. In conclusion, IH60 led to oxygen fluctuations in liver and muscle and steady hypoxia in fat. IH and SH induced insulin resistance, but inflammation was increased only by IH60 in lean mice. Obesity caused severe inflammation, which was not augmented by acute hypoxic regimens.

Hypoxia-induced inflammatory cytokine secretion in human adipose tissue stromovascular cells

AIMS

Hypoxia has been implicated as a cause of adipose tissue inflammation in obesity, although the inflammatory response of human adipose tissue to hypoxia is not well understood. The goal of this study was to define in vitro inflammatory responses of human adipose tissue to hypoxia and identify molecular mechanisms of hypoxia-induced inflammation.

METHODS

The inflammatory milieu and responses of visceral (VAT) and subcutaneous (SAT) adipose tissue explants and purified stromovascular cells (SVFs) from obese and lean humans were studied in an in vitro hypoxic culture system using quantitative real-time PCR, ELISA, western blotting, immunofluorescence microscopy, flow cytometry and immunohistochemistry.

RESULTS

Human adipose tissue in obesity demonstrates an increased leucocyte infiltrate that is greater in VAT than SAT and involves macrophages, T cells and natural killer (NK) cells. Hypoxic culture regulates inflammatory cytokine secretion and transcription of metabolic stress response genes in human adipose tissue SVF. Adipocyte diameter is increased and adipose tissue capillary density is decreased in obese participants. Inhibition of c-Jun terminal kinase (JNK) or p38 significantly attenuates hypoxia-induced SVF inflammatory responses. Hypoxia induces phosphorylation of p38 in adipose tissue.

CONCLUSIONS

Human adipose tissue in obesity is characterised by a depot-specific inflammatory cell infiltrate that involves not only macrophages, but also T cells and NK cells. Hypoxia induces inflammatory cytokine secretion by human adipose tissue SVF, the primary source of which is adipose tissue macrophages. These data implicate p38 in the regulation of hypoxia-induced inflammation and suggest that alterations in adipocyte diameter and adipose tissue capillary density may be potential underlying causes of adipose tissue hypoxia.