[Effects of crowding on immune functions in mice]

Chronic effect of training on neutrophil functions in humans

We performed this study to evaluate the chronic effect of training on neutrophil functions in humans. Twenty-six university students (14 males and 12 females) with a mean age of 19.1±0.8 years were divided into the athlete group and the control group based on answers given to a written questionnaire. The capacity of circulating neutrophils to ingest bacteria (phagocytosis) and to produce superoxide (nitroblue tetrazolium reduction) was measured under resting conditions in the absence of training activities. In addition, we measured hematological and serum biochemical parameters.The present analyses revealed that the frequency of subjective symptoms concerning susceptibility to infections (sum of males and females) was higher in the athlete group than in the control group (p<0.05). In the investigation of males, hemoglobin and serum protein levels of the athlete group were lower than that of the control group (p<0.01, p<0.05, respectively). Although total and differential leukocyte counts, and phagocytic activity of neutrophils were not significantly different between the groups, superoxide productivity of neutrophils in the male athlete group was higher than that in the control group (p<0.05).Since significant differences were observed in hemoglobin and serum protein levels in the male athletes, the training is considered to have been intense. An increase was noted in the neutrophil superoxide production along with these changes, but no significant difference was observed in the phagocytic activity. Therefore, there is the possibility of superoxide overproduction, which may lead to tissue damage.

Effects of life events and stress on neutrophil functions in elderly men

Background

Psychological stress or life events might significantly decrease neutrophil function in elderly individuals and lead to infectious diseases. However, relationships between these factors have not been examined in detail.

We investigated the relationships between neutrophil function measured using the nitroblue tetrazolium (NBT) reduction test and measurements of psychological stress and life events among 81 men aged over 60 years.

Results

The numbers and scores for life events were significantly higher (p < 0.01, respectively) in a group with values reflecting phagocytosis below the median than in a control group.

Conclusions

Chronic psychological stress due to life events decreases neutrophil functions among elderly men.

The intervention of antioxidant therapy on platelet adhesion and immunomodulation in experimental physical stress

During effort overstress the reactive oxygen species act chiefly on unsaturated lipids, inducing the formation of certain peroxidation products. We have investigated malondialdehide (MDA), platelet adhesion index, and immunological activation parameters during effort overstress and administration of vitamins E and C. Biochemical measurements were performed on erythrocytes and heart homogenate. In the vitamin E supplemented group, the platelet adhesion index was constantly correlated with the MDA level (p < 0.001). There is a protecting effect concerning the oxidative stress in animals pretreated with vitamin E and C, which is expressed through the diminution of the MDA quantity both in the erythrocyte and in the heart. The physical effort required by swimming led to a decrease in the NBT test values and in the activity of the serum complement. The steady administration of vitamin E in the effort overstress, due to its antioxidant properties, causes the progressive decrease in peroxidation and platelet adhesion.

Physiological profile of juvenile rats: effects of cage size and cage density

Although there is a general consensus that housing conditions affect the well-being of laboratory animals, the ideal cage size and density for housing laboratory rodents has not been established. The authors investigated the effects of cage size and cage density on growth, organ development, metabolic profile, and hemogram in juvenile Sprague-Dawley rats. Larger cages and increased cage density were associated with depressions in body weight and in the weights of several organs. In general, increasing group size and density correlated more strongly with detrimental effects on the growth of females than males, although hemogram values indicated that males are more prone to emotional stress and immune suppression than females in response to increasing group size and crowding.

Relationships between lifestyle factors and neutrophil functions in the elderly

We investigated the relationships between neutrophil functions and lifestyle factors in the elderly. The subjects (84 males, 73.9+/-5.8 years old; and 63 females, 70.0+/-4.6 years old) belonged to a recreational seniors club in Japan. Investigations of the subjects' stress, exercise habits, smoking habits, and alcohol-drinking habits were performed. The phagocytosis and superoxide productivity of the neutrophils were measured with a nitroblue tetrazolium (NBT) reduction test. In addition, leukocyte counts and serum total protein (TP) levels were determined. The results revealed that aging, high serum levels, and stress-coping factors (e.g., having hobbies, keeping pets, and close links with friends or family) significantly correlated with preferable neutrophil functions. In addition, significant effects of lifestyle factors on the balance between phagocytosis and subsequent superoxide production were observed. Thus, the results of the present study suggest that there are correlations between neutrophil functions and lifestyle factors in the elderly.

Importance of correlations between phagocytic activity and superoxide production of neutrophils under conditions of voluntary exercise and stress

The importance of the neutrophil function to host defense and tissue damage has been widely recognized. However, the usefulness of the correlation analysis between phagocytic activity and superoxide production of neutrophils is unknown. We investigated the relationship by histochemical NBT assay using rats and mice exposed to voluntary exercises and stresses. The following conclusions were shown from the results in this report and from our previously published findings. The results of voluntary exercise showed significant positive correlations between phagocytic activity and superoxide production of neutrophils after the continuation of the exercise for 8 months, but no relationship after only 3 or 4 months. However, when Salmonella was injected into the same group after 4 months, significant positive correlations were observed immediately following and on the 6th and 14th days after injection. In contrast, negative correlations emerged after psychological stress and severe-crowding stress, suggesting that appropriate expression of neutrophil function was disturbed by the reverse effects, such as by suppression of oxygen-dependent killing capacity or over-production of toxic free radicals subsequent to these stress. These results suggest that the correlations of phagocytic activity and superoxide production of neutrophils reflect whether a neutrophil functional state is appropriate or not.