Body fat of rats of different age groups and nutritional states: assessment by micro-CT and skinfold thickness

Obesity presents a growing public health problem. Therefore the analysis of body composition is important in clinical practice as well as in animal research models of obesity; hence precise methods for the assessment of body fat would be essential. We aimed to evaluate in vivo abdominal microcomputed tomography scan restricted to the L1-L3 region [micro-CT_(L1-L3)], a skinfold thickness-based method (STM), and postmortem body composition analysis (PMA) with regard to whole body micro-CT scan in rats. Male Wistar rats of different age groups (from 3 to 24 mo) and nutritional states (normally fed, high-fat diet-induced obese, and calorie-restricted) were used. The fat percentage was determined with micro-CT_(L1-L3) and whole body scan in anesthetized rats. Their skinfold thickness was measured in five locations with a Lange caliper. Wet weights of epididymal and retroperitoneal fat pads were determined via PMA. With regard to fat mass, the strongest correlation was observed between abdominal and whole body micro-CT. The other methods showed weaker associations with whole body micro-CT and with each other. Micro-CT_(L1-L3) and PMA showed similar age-associated increase in fat mass between 3 and 18 mo. Micro-CT_(L1-L3), STM, and PMA were efficient to detect differences in fat mass values in groups of different nutritional states. Micro-CT_(L1-L3) appears to be a useful method for body fat assessment in rats with reduced scanning time. In rats, STM may also be a useful, low priced, noninvasive, and simple in vivo technique to assess obesity. NEW & NOTEWORTHY Body fat of rats assessed by in vivo abdominal microcomputed tomography of the L1-L3 region strongly correlates with values determined by whole body scan. Therefore, it is a useful method for fat assessment with reduced scanning time. Skinfold thickness measurement is an in vivo technique to assess progression of obesity in rats.

Fever Is Associated with Reduced, Hypothermia with Increased Mortality in Septic Patients: A Meta-Analysis of Clinical Trials

Background

Sepsis is usually accompanied by changes of body temperature (T_b), but whether fever and hypothermia predict mortality equally or differently is not fully clarified. We aimed to find an association between T_b and mortality in septic patients with meta-analysis of clinical trials.

Methods

We searched the PubMed, EMBASE, and Cochrane Controlled Trials Registry databases (from inception to February 2016). Human studies reporting T_b and mortality of patients with sepsis were included in the analyses. Average T_b with SEM and mortality rate of septic patient groups were extracted by two authors independently.

Results

Forty-two studies reported T_b and mortality ratios in septic patients (n = 10,834). Pearson correlation analysis revealed weak negative linear correlation (R² = 0.2794) between T_b and mortality. With forest plot analysis, we found a 22.2% (CI, 19.2–25.5) mortality rate in septic patients with fever (T_b > 38.0°C), which was higher, 31.2% (CI, 25.7–37.3), in normothermic patients, and it was the highest, 47.3% (CI, 38.9–55.7), in hypothermic patients (T_b < 36.0°C). Meta-regression analysis showed strong negative linear correlation between T_b and mortality rate (regression coefficient: -0.4318; P < 0.001). Mean T_b of the patients was higher in the lowest mortality quartile than in the highest: 38.1°C (CI, 37.9–38.4) vs 37.1°C (CI, 36.7–37.4).

Conclusions

Deep T_b shows negative correlation with the clinical outcome in sepsis. Fever predicts lower, while hypothermia higher mortality rates compared with normal T_b. Septic patients with the lowest (< 25%) chance of mortality have higher T_b than those with the highest chance (> 75%).