Active duty service members who sustain a traumatic brain injury have chronically elevated peripheral concentrations of Aß40 and lower ratios of Aß42/40.

PRIMARY OBJECTIVE: Excessive accumulation of amyloid beta (Aß) and tau have been observed in older individuals with chronic neurological symptoms related to a traumatic brain injury (TBI), yet little is known about the possible role of Aß in younger active duty service members following a TBI. The purpose of the study was to determine if Aß 40 or 42 related to sustaining a TBI or to chronic neurological symptoms in a young cohort of military personnel. RESEARCH DESIGN: This was a cross-sectional study of active duty service members who reported sustaining a TBI and provided self-report of neurological and psychological symptoms and provided blood. METHODS AND PROCEDURES: An ultrasensitive single-molecule enzyme-linked immunosorbent assay was used to compare concentrations of Aß in active duty service members with (TBI+; n = 53) and without (TBI-; n = 18) a history of TBI. Self-report and medical history were used to measure TBI occurrence and approximate the number of total TBIs and the severity of TBIs sustained during deployment. MAIN OUTCOMES AND RESULTS: This study reports that TBI is associated with higher concentrations of Aß40 (F1,68 = 6.948, p = 0.009) and a lower ratio of Aß42/Aß40 (F1,62 = 5.671, p = 0.020). These differences remained significant after controlling for co-morbid symptoms of post-traumatic stress disorder and depression. CONCLUSIONS: These findings suggest that alterations in Aß relate to TBIs and may contribute to chronic neurological symptoms.

A murine model of peripheral irradiation-induced fatigue.

PURPOSE: Fatigue is the most ubiquitous side effect of cancer treatment, but its etiology remains elusive. Further investigations into cancer-related fatigue pathobiology necessitate the expanded use of animal models. This study describes the development of a murine model of radiation-induced fatigue. METHODS: Voluntary wheel running activity measured fatigue in 5-8 week-old, male C57BL/6 mice before and after γ irradiation totaling 2400cGy (3 consecutive days×800cGy daily fractionated doses) to the lower abdominal areas. Three trials confirmed fatigue behavior at this dose. Anhedonia, body weight, and hemoglobin were also measured. Gastrointestinal, skeletal muscle, and bone marrow tissue samples were evaluated for signs of damage. RESULTS: In two validation trials, irradiated mice (trial 1, n=8; trial 2, n=8) covered less cumulative distance in kilometers post-irradiation (trial 1, mean=115.3±12.3; trial 2, mean=113.6±21.8) than sham controls (trial 1, n=5, mean=126.3±5.7, p=0.05; trial 2, n=8, mean=140.9±25.4, p=0.02). Decreased mean daily running distance and speed were observed during the last four hours of the dark cycle in irradiated mice compared to controls for two weeks post-irradiation. There were no differences in saccharin preference or hemoglobin levels between groups, no effect of changes in body weight or hemoglobin on wheel running distance, additionally, histology showed no damage to muscle, bone marrow, or gastrointestinal integrity, with the latter confirmed by ELISA. CONCLUSION: We characterized a novel mouse model of fatigue caused by peripheral radiation and not associated with anemia, weight changes, or anhedonia. This model provides opportunities for detailed study of the mechanisms of radiation-induced fatigue.

Sickness behavior induced by cisplatin chemotherapy and radiotherapy in a murine head and neck cancer model is associated with altered mitochondrial gene expression.

The present study was undertaken to explore the possible mechanisms of the behavioral alterations that develop in response to cancer and to cancer therapy. For this purpose we used a syngeneic heterotopic mouse model of human papilloma virus (HPV)-related head and neck cancer in which cancer therapy is curative. Mice implanted or not with HPV+ tumor cells were exposed to sham treatment or a regimen of cisplatin and radiotherapy (chemoradiation). Sickness was measured by body weight loss and reduced food intake. Motivation was measured by burrowing, a highly prevalent species specific behavior. Tumor-bearing mice showed a gradual decrease in burrowing over time and increased brain and liver inflammatory cytokine mRNA expression by 28 days post tumor implantation. Chemoradiation administered to healthy mice resulted in a mild decrease in burrowing, body weight, and food intake. Chemoradiation in tumor-bearing mice decreased tumor growth and abrogated liver and brain inflammation, but failed to attenuate burrowing deficits. PCR array analysis of selected hypoxia and mitochondrial genes revealed that both the tumor and chemoradiation altered the expression of genes involved in mitochondrial energy metabolism within the liver and brain and increased expression of genes related to HIF-1α signaling within the brain. The most prominent changes in brain mitochondrial genes were noted in tumor-bearing mice treated with chemoradiation. These findings indicate that targeting mitochondrial dysfunction following cancer and cancer therapy may be a strategy for prevention of cancer-related symptoms.