Metabolic responses to tyramine and cold in young male Sprague-Dawley and Fischer 344 rats

Serum metabolomics analysis of patients with chikungunya and dengue mono/co-infections reveals distinct metabolite signatures in the three disease conditions

Chikungunya and dengue are arboviral infections with overlapping clinical symptoms. A subset of chikungunya infection occurs also as co-infections with dengue, resulting in complications during diagnosis and patient management. The present study was undertaken to identify the global metabolome of patient sera infected with chikungunya as mono infections and with dengue as co-infections. Using nuclear magnetic resonance (NMR) spectroscopy, the metabolome of sera of three disease conditions, namely, chikungunya and dengue as mono-infections and when co-infected were ascertained and compared with healthy individuals. Further, the cohorts were analyzed on the basis of age, onset of fever and joint involvement. Here we show that many metabolites in the serum are significantly differentially regulated during chikungunya mono-infection as well as during chikungunya co-infection with dengue. We observed that glycine, serine, threonine, galactose and pyrimidine metabolisms are the most perturbed pathways in both mono and co-infection conditions. The affected pathways in our study correlate well with the clinical manifestation like fever, inflammation, energy deprivation and joint pain during the infections. These results may serve as a starting point for validations and identification of distinct biomolecules that could be exploited as biomarker candidates thereby helping in better patient management.

Age-related differences in response to acute cold challenge (-10 degrees C) in male F344 rats

Male F344 rats, 3, 12, and 24 months of age, were acclimated to either 5 degrees C (CA) or 23 degrees C (non-CA). At the end of acclimation, all CA rats exhibited higher basal oxygen uptake than the non-CA when measured at 28 degrees C. When challenged by a 3-hour exposure to -10 degrees C, significant difference in tolerance to cold was observed not only between the CA and non-CA rats but among the different age groups. The 3-month-olds tolerated cold better than 12-month-olds, and the 12-month-olds did better than the 24-month-olds. The ranking order for cold tolerance in -10 degrees C was: 3-month CA greater than 12-month CA greater than 3-month non-CA = 12-month non-CA = 24-month CA greater than 24-month non-CA. Total 3-hour O2 uptake decreased progressively with advancing age. Heat productions were doubled in -10 degrees C in all age groups, and all CA rats had higher heat production than non-CAs. The increase of heat production in -10 degrees C was insufficient to maintain body temperature in all animals. All animals had loss of body heat content, the loss becoming greater with advancing age. Non-CA rats had greater loss of heat content or faster decline of colonic temperature than the CAs. Significant strain-related difference in cold tolerance was noted between the F344 and Sprague-Dawley (S-D) rats, because 24-month-old non-CA male F344 rats still exhibited a better tolerance to -10 degrees C than 3-month-old CA S-D rats.