Respiratory quotient evolution during normal pregnancy: what nutritional or clinical information can we get out of it?

Food intake increases to a varying extent during pregnancy to provide extra energy for the growing fetus. Measuring the respiratory quotient (RQ) during the course of pregnancy (by quantifying O2 consumption and CO2 production with indirect calorimetry) could be potentially useful since it gives an insight into the evolution of the proportion of carbohydrate vs. fat oxidized during pregnancy and thus allows recommendations on macronutrients for achieving a balanced (or slightly positive) substrate intake. A systematic search of the literature for papers reporting RQ changes during normal pregnancy identified 10 papers reporting original research. The existing evidence supports an increased RQ of varying magnitude in the third trimester of pregnancy, while the discrepant results reported for the first and second trimesters (i.e. no increase in RQ), explained by limited statistical power (small sample size) or fragmentary data, preclude safe conclusions about the evolution of RQ during early pregnancy. From a clinical point of view, measuring RQ during pregnancy requires not only sophisticated and costly indirect calorimeters but appears of limited value outside pure research projects, because of several confounding variables: (1) spontaneous changes in food intake and food composition during the course of pregnancy (which influence RQ); (2) inter-individual differences in weight gain and composition of tissue growth; (3) technical factors, notwithstanding the relatively small contribution of fetal metabolism per se (RQ close to 1.0) to overall metabolism of the pregnant mother.

The Tightness of the Cotton Swabs Meshing Influences the Chances of Getting Conclusive DNA Profiles

Objective: The chance of obtaining a conclusive DNA profile strongly depends on the quantity of biological material that can be recovered from a crime scene sample. Optimizing the collection strategy is therefore of prime interest. A difference in the level of tightness of the cotton meshed around the shaft has been observed between manufacturers and is hypothesized to affect the collection and subsequent release capacity of cotton swabs. Consequently, we compared the performance of cotton swabs from two different suppliers: Applimed SA and DryswabTM. Methods: These swabs were used to recover 50 ml of blood, either pure or diluted (1:1000 and 1:5000), deposited on both smooth and absorbent surfaces. Performance was compared in terms of ease of use, concentration of extracted DNA, and quality of DNA profiles. DNA quantification was obtained by real-time PCR using the QuantifilerTM Human DNA Quantification Kit. Evaluation of DNA profiles was based on profiles obtained using AmpFlSTR® NGM SElectTM PCR Amplification kit. Results: When considering smooth surfaces, recovered DNA was more concentrated when using the DryswabTM than the Applimed SA cotton swab. More precisely, DNA concentrations ranged from 15.7 to 28.8 ng/ml and 6.7 to 21.2 ng/ml, respectively for samples of pure blood. The same trend was observed for the absorbent surface, with 2.0 to 5.0 ng/ml and 0.9 to 1.4 ng/ml, respectively. Conclusion: Our results illustrate that different cotton swabs produce different results in terms of ease of use and quantity of recovered DNA and this should be taken into consideration when choosing which swab to use at both the crime scene and laboratory. More specifically, results from the present study suggest that looser meshing of the cotton fibres