Adipose tissue: a neglected organ in the response to severe trauma?

Passive mechanical properties of adipose tissue and skeletal muscle from C57BL/6J mice

Skeletal muscle and adipose tissue are characterized by unique structural features finely tuned to meet specific functional demands. In this study, we investigated the passive mechanical properties of soleus (SOL), extensor digitorum longus (EDL) and diaphragm (DIA) muscles, as well as subcutaneous (SAT), visceral (VAT) and brown (BAT) adipose tissues from 13 C57BL/6J mice. Thereto, alongside stress-relaxation assessments we subjected isolated muscles and adipose tissues (ATs) to force-extension tests up to 10% and 30% of their optimal length, respectively. Peak passive stress was highest in the DIA, followed by the SOL and lowest in the EDL (p < 0.05). SOL displayed also the highest Young's modulus and hysteresis among muscles (p < 0.05). BAT demonstrated highest peak passive stress and Young's modulus followed by VAT (p < 0.05), while SAT showed the highest hysteresis (p < 0.05). When comparing data across all six biological specimens at fixed passive force intervals (i.e., 20-40 and 50-70 mN), skeletal muscles exhibited significantly higher peak stresses and strains than ATs (p < 0.05). Young's modulus was higher in skeletal muscles than in ATs (p < 0.05). Muscle specimens exhibited slower force relaxation in the first phase compared to ATs (p < 0.05), while there was no significant difference in behavior between muscles and AT in the second phase of relaxation. The study revealed distinctive mechanical behaviors specific to different tissues, and even between different muscles and ATs. These variations in mechanical properties are likely such to optimize the specific functions performed by each biological tissue.

The Impact of Body Mass Composition on Outcome in Multiple Traumatized Patients—Results from the Fourth Thoracic and Third Lumbar Vertebrae: A Single-Center Retrospective Observational Study

Background: Body mass composition (BC) was shown to correlate with outcome in patients after surgery and minor trauma. As BC is assessed using computed tomography (CT) and routinely applied in multiple trauma (MT), this study will help to analyze whether BC variables also correlate with outcome in trauma patients. Materials and Methods: Inclusion criteria were MT (Injury Severity Score (ISS) > 15) and whole-body CT (WBCT) scan on admission. Muscle and fat tissue were assessed at the level of the fourth thoracic vertebra (T4) and the third lumbar vertebra (L3) using Slice-O-matic software, version 5.0 (Tomovision, Montreal, QC, Canada). Univariate and multivariate regression models were used with regard to outcome parameters such as duration of ventilation, hospital stay, local (i.e., pneumonia, wound infection) and systemic (i.e., MODS, SIRS) complications, and mortality. Results: 297 patients were included. BC correlated with both the development and severity of complications. Skeletal muscle index (SMI) and subcutaneous adipose tissue index (SATI) at both T4 and L3 correlated positively with the occurrence of systemic infections. Local infections positively correlated with SMI at T4. Low muscle mass and high visceral adipose tissue (VAT) predicted the severity of systemic and local complications. Muscle tissue markers at both T4 and L3 predicted the severity of complications in roughly the same way. Moreover, higher muscle mass at the L3 level was significantly associated with higher overall survival, while SATI at the T4 level correlated positively with hospital stay, length of stay in the ICU, and duration of ventilation. Conclusions: A lower muscle mass and a high adipose tissue index are associated with a poor outcome in MT. For the first time, it was shown that BC at the fourth thoracic vertebra is associated with comparable results to those found at the third lumbar level.

High Fat-to-Muscle Ratio Was Associated with Increased Clinical Severity in Patients with Abdominal Trauma

Overweight and moderate obesity confer a survival benefit in chronic diseases such as coronary artery disease and chronic kidney disease, which has been termed the "obesity paradox". However, whether this phenomenon exists in trauma patients remains controversial. We performed a retrospective cohort study in abdominal trauma patients admitted to a Level I trauma center in Nanjing, China between 2010 and 2020. In addition to the traditional body mass index (BMI) based measures, we further examined the association between body composition-based indices with clinical severity in trauma populations. Body composition indices including skeletal muscle index (SMI), fat tissue index (FTI), and total fat-to-muscle ratio (FTI/SMI) were measured using computed tomography. Our study found that overweight was associated with a four-fold risk of mortality (OR, 4.47 [95% CI, 1.40-14.97], p = 0.012) and obesity was associated with a seven-fold risk of mortality (OR, 6.56 [95% CI, 1.07-36.57], p = 0.032) compared to normal weight. Patients with high FTI/SMI had a three-fold risk of mortality (OR, 3.06 [95% CI, 1.08-10.16], p = 0.046) and double the risk of an intensive care unit length of stay ≥ 5 d (OR, 1.75 [95% CI, 1.06-2.91], p = 0.031) compared to patients with low FTI/SMI. The obesity paradox was not observed in abdominal trauma patients, and high FTI/SMI ratio was independently associated with increased clinical severity.

A systematic review and meta-analysis of the effect of obesity on patients undergoing lower extremity revascularization

OBJECTIVE

In the present review, we assessed the effect of obesity on clinical outcomes for patients with peripheral arterial disease who had undergone endovascular or open lower extremity revascularization surgery.

METHODS

A systematic search strategy of MEDLINE, EMBASE, CINAHL, Web of Science, and Cochrane Library was conducted. The included studies had compared obese and nonobese cohorts with peripheral arterial disease who had undergone endovascular or open lower extremity revascularization. The outcomes included mortality, major adverse cardiovascular events, major adverse limb events, surgical site infections, endovascular access site complications, and perioperative complications.

RESULTS

Eight studies were included with 171,648 patients. The obese patients (body mass index ≥30 kg/m²) were more likely to be women, to have diabetes, and to have more cardiovascular comorbidities despite being younger. No association was found between obesity and peripheral arterial disease severity. Obesity was associated with an overall 22% decreased mortality risk after lower extremity revascularization (risk ratio [RR], 0.78; 95% confidence interval [CI], 0.71-0.85; P < .001; I² = 0%; GRADE (grading of recommendations assessment, development, evaluation), very low quality). A subgroup analysis by intervention type showed similar findings (endovascular: RR, 0.79; 95% CI, 0.71-0.87; P < .001; I² = 0%; open: RR, 0.70; 95% CI, 0.51-0.95; P = .024; I² = 43%). Obesity was associated with a 14% decreased risk of major adverse cardiovascular events for open surgery only (RR, 0.86; 95% CI, 0.76-0.98; P = .021; I² = 0%; GRADE, very low quality). Obesity was associated with an increased risk of surgical site infections pooled across intervention types (RR, 1.69; 95% CI, 1.34-2.14; P < .001; I² = 78%; GRADE, very low quality). No association was found between obesity and major adverse limb events (RR, 1.02; 95% CI, 0.93-1.11; P = .73; I² = 15%; GRADE, very low quality) or endovascular access site complications (RR, 1.11; 95% CI, 0.76-1.63; P = .58; I² = 86%; GRADE, very low quality). Pooled perioperative complications did not differ between the obese and nonobese cohorts (RR, 1.04; 95% CI, 0.84-1.28; P = .73; I² = 92%; GRADE, very low quality).

CONCLUSIONS

Obesity was associated with reduced mortality risk with both endovascular and open surgery, although a reduction in major adverse cardiovascular events was only observed with open surgery. In addition, obese patients had an increased risk of surgical site infections. Obesity was not associated with major adverse limb events, endovascular access site complications, or perioperative complications. The GRADE quality of evidence was very low. The findings from the present review suggest a survival advantage for obese patients with peripheral arterial disease. Future studies could focus on prospectively investigating the effect of obesity on peripheral arterial disease outcomes. A nuanced evaluation of body mass index as a preoperative risk factor is warranted.

Microbiota-Pain Association; Recent Discoveries and Research Progress

The relationship between gut microbiota and pain, such as visceral pain, headaches (migraine), itching, prosthetic joint infection (PJI), chronic abdominal pain (CAP), joint pain, etc., has received increasing attention. Several parts of the evidence suggest that microbiota is one of the most important pain modulators and they can regulate pain in the central and peripheral nervous systems. Any alteration in microbiota by diet or antibiotics mediation may characterize a novel therapeutic strategy for pain management. The present study includes the most up-to-date and influential scientific findings on the association of microbiota with pain, despite the fact that the underlying mechanism is not identified in most cases. According to recent research, identifying the molecular mechanisms of the microbiota-pain pathway can have a unique perspective in treating many diseases, even though there is a long way to reach the ideal point. This study will stress the influence of microbiota on the common diseases that can stimulate the pain with a focus on underlying mechanisms.

Exploring the alterations and function of skin microbiome mediated by ionizing radiation injury

Background

Radiation-induced skin injury (RISI) is still the most common and severe side effect of radiotherapy. The role of the skin’s microbial barrier in the pathogenesis and progression of RISI needs to be fully investigated.

Methods

This study aimed to explore the alterations in and functions of the skin microbiota in RISI. We applied the unculturable approach to characterize the cutaneous microbiomes of a radiation-induced animal model by sequencing the V1–V3 regions of the 16S ribosomal RNA (rRNA) gene. Combined with the downloaded clinical data of patients, a comprehensive analysis was performed to identify potential radioprotective species and metabolic pathways.

Results

There were no significant differences in the alpha diversity indices (Sobs, Shannon, Simpson, Ace, and Chao) between the acute radiation injury and control groups. Phylum-level analysis of the RISI microbiomes exhibited significant predominance of Firmicutes (mean abundance = 67%, corrected p = 0.0035). The high abundance of Firmicutes was significantly associated with rapid healing of RISI (average relative abundance = 52%; Kruskal–Wallis: p = 5.7E−4). Among its members, Streptococcus, Staphylococcus, Acetivibrio ethanolgignens group, Peptostreptococcus, Anaerofilum, and UCG-002 [linear discriminant analysis (LDA) &gt; 3, p &lt; 0.05] were identified as the core genera of Firmicutes. In addition, Lachnosiraceae and Lactobacillus occupied an important position in the interaction network (r &gt; 0.6, p &lt; 0.05). The differential metabolic pathways of RISI were mainly associated with carbohydrate metabolism (butanoate and propanoate metabolism), amino acid metabolism (tryptophan and histidine metabolism), energy metabolism, and lipid metabolism (fatty acid degradation and biosynthesis).

Conclusion

This study provides new insights into the potential mechanism and skin microbial changes in the progression of RISI. The overwhelming predominance of members of Firmicutes, including Streptococcaceae, Staphylococcaceae, Lachnospiraceae, and Lactobacillus, is potentially related to rapid healing of RISI. The microbiota–metabolite axis plays a critical role in RISI and provides promising therapeutic targets for the treatment of adverse side effects.

Prospective Association of Circulating Adipokines with Cardiometabolic Risk Profile Among Women: The Rape Impact Cohort Evaluation Study

BACKGROUND

Sexual violence is associated with poor cardiometabolic outcomes, yet the etiopathogenic pathways remain unclear. Adipokines may contribute to pathways in the development of cardiometabolic disease (CMD), including in vulnerable populations. Further investigation of adipokines among sexually traumatized individuals may inform cardiometabolic screening. This study aimed to investigate the association between circulating adipokines, metabolic syndrome (MetS), and longitudinal change in MetS components (namely abdominal obesity, blood pressure, lipid profile, and glycemic status) over a 1-year period in a cohort of rape exposed (RE) and rape unexposed (RUE) females.

MATERIALS AND METHODS

Seven hundred seventy-eight RE and 617 RUE black South African women aged 18-40 years were recruited for the Rape Impact Cohort Evaluation study. Nonfasting blood samples were analyzed for cardiometabolic variables and adipokine levels using enzyme-linked immunosorbent assay. Serum adiponectin was measured in both RE and RUE and resistin, leptin, and leptin/adiponectin (L/A) ratio in RE only. Associations between baseline serum adipokines, MetS, and its components were assessed at baseline and follow-up using adjusted linear and logistic regressions.

RESULTS

In the RE group, adiponectin, leptin, and L/A ratio were significantly associated with MetS prevalence cross-sectionally (all p ≤ 0.001). No adipokine marker was related to incident MetS at 12-month follow-up. In the RE group, significant longitudinal associations with high-density lipoprotein cholesterol were shown for adiponectin (β = 0.146 [0.064], p = 0.022) and leptin (β = 0.001 [0.002], p = 0.012).

CONCLUSIONS

Findings suggest that adipokines may have a potential role as biomarkers to identify RE individuals at high risk for CMD.