Background: Social stress is a factor involved in the etiology of many diseases. Also, gender is another factor which predisposes individuals to certain disease. Results from animal and human studies suggest that socially-stressed men are more vulnerable to catching diseases compared to socially-stressed women. Materials and Methods:The role of chronic social stress and gender were examined in the present study through implementing food deprivation, food intake inequality, and unstable social status (cagemate change every three days) for a period of 14 days on 96 male and female mice. Then, vital activity of peritoneal macrophages and spleen's lymphocytes were measured using MTT test as well as the concentration of Tumor Necrosis Factor-alpha (TNF-α) by ELISA technique. Results:Our results showed that cell viability of peritoneal macrophages and spleen's lymphocytes as well as serum concentration of TNF-α in all female and male stressed animals increased compared to the controls (P<0.05). Moreover, gender differences in immune function were also apparent; these changes were more prominent in female mice. Conclusion:The results suggest that social factors have significant effects on immunity and should be considered in the studies of gender differences for evaluating possible effective mechanisms.

Objective(s): We aimed to show that the immune system is sensitive to the detrimental effects of inequality and social injustice, and splenic vulnerability to apoptosis may also increase. Methods: In order of better determination of immune responses to chronic social stress, we implemented food deprivation, food intake inequality, and unstable social status (a change of cage-mate every 3 days) for a period of 14 days in 60 male Balb/c mice. At the end of this stress period, nitric oxide (NO) production by peritoneal adherent cells and the serum concentration of corticosterone were measured. Moreover, the viability of peritoneal adherent cells and spleen lymphocytes was evaluated by MTT assay. The terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was done to reveal the TUNEL-reactive apoptotic bodies in the spleen. Results: Our results showed that food deprivation and inequality caused significant changes in the apoptosis of splenic cells in comparison with the control group (p < 0.05). Moreover, the vital activities of lymphocytes and peritoneal adherent cells, as well as NO production by the latter, increased significantly (p < 0.05). However, the experience of unstable social status did not cause a further increase in the viability of lymphocytes and peritoneal adherent cells, or NO production in animals that were food-deprived or experienced inequality. Serum concentration of corticosterone in all experimental groups, except for animals that experienced unstable social status only, significantly decreased versus the control group (p < 0.05). Conclusions: The results suggest that poverty and social inequality, but not unstable social status, affect immune responses and are likely involved in the induction of splenic apoptosis in mice.

The velocity distribution and heat transfer improvement in a two-dimensional channel filled with a water-CuO nanofluid is numerically studied. The nanofluid flow is assumed laminar and one-phase with Newtonian behaviour. Pure water is considered as the base fluid, and water-CuO nanofluid with four different volume fractions of CuO nanoparticles are examined. A constant heat source–sink is considered to cover the entire length of the bottom wall of the channel while the upper wall is assumed thermally insulated. The control volume technique is used to discretize the governing differential equations, and the SIMPLE algorithm is used to solve the velocity-pressure coupling. A CFD simulation is applied on nanofluid flow utilizing ANSYS FLUENT to solve the governing equations of the flow. The effects of nanoparticle volume fraction on the heat transfer, velocity profile, wall shear stress, skin friction coefficient, and Nusselt number along the channel have also been examined. The results confirm that the volume fraction of nanoparticles plays an important role in heat transfer enhancement and hydrodynamic behaviour of flow. The results are presented in figures and tables.