Recent converging evidence suggests that the brain may receive stimuli and possibly modulate tumor progression via the vagus nerve. The present study aimed to compare brain metabolism in patients with and without lung cancer and to assess if significant differences exist in regions associated with the vagus nerve. Methods: Eighteen patients with lung malignancy and 19 controls underwent 18 F-FDG PET of the brain. Brain metabolism was compared using statistical parametric mapping. Results: Patients with lung malignancy showed a statistically significantly higher right cerebellar metabolism. Conclusion: This finding may be related to the role of the cerebellum in immune regulation, because of its proximity to the nucleus tractus solitarius innervated by the vagus and its connections with the hypothalamus. This higher metabolism in the right cerebellum may reflect an attempt to reinstate homeostasis in functions such as respiration and immunity pertinent to lung malignancy. Cancer research has shifted from solely focusing on genetic aspects and defining the intracellular etiology of tumorigenesis to also assessing interactions between tumors and their microenvironment (1). Furthermore, there is increasing interest in assessing the potential presence of bidirectional links between peripheral malignant tumors and the brain, in the form of tumor-to-brain communication and modulation (2).The inflammatory microenvironment plays a crucial role early during tumorigenesis (3,4) and later for angiogenesis and tumor invasion (5). The brain receives signals from peripheral inflammatory processes by several routes, including the vagus (6), through interleukin-1 receptors on its paraganglia. There are conflicting reports on the rate of cancer-related death in vagotomized ulcer patients (7,8). However, chemical and surgical vagotomy prevents tumorassociated anorexia in mice (9) and enhances the metastasizing rate of peripheral malignant tumors (10). In view of these studies, it has been hypothesized that the vagus (and potentially other neural routes) may provide signals about the presence of malignancy-related inflammation to the brain with possible subsequent modulation of tumorigenesis (2,11).The present study aimed to examine brain metabolism in patients with lung malignancy, addressing most of the limitations of prior studies (12-15). Most patients included in the study were evaluated because of pulmonary nodules detected on CT. Both patients and physicians were unaware of the final diagnosis with respect to the presence of active malignancy at the time of imaging, which was performed before any treatment. MATERIALS AND METHODS Patients and Control SubjectsEighteen patients with lung malignancy and 19 controls were included. The malignancy group consisted only of newly diagnosed, histologically proven cases of cancer and included 16 patients with non-small cell lung cancer ( The control group comprised a subgroup of 8 patients with lymphoma in remission for at least 4 y (the LymC group), including Hodgkin lymphoma (n 5 2, s...

We previously reported that a decreased TCR mediated activity of the GTP-GDP binding p21ras protooncogene is associated with prediabetes in non-obese diabetic (NOD) mice. Furthermore, prevention of autoimmune diabetes is associated with reversal of the p21ras signaling defect in NOD T cells. Based on these animal studies we determined the activation of p21ras in PBMC from patients with Insulin Dependent Diabetes Mellitus (IDDM), Non-Insulin Dependent Diabetes Mellitus (NIDDM) and normal healthy controls. Stimulation by PHA induced a decrease of 3.7 +/- 1.4% and an increase of 2.44 +/- 2.3%, p < 0.02 and 2.6 +/- 1.6%,p < 0.003 in the basal unstimulated p21ras activity in the IDDM, NIDDM and normal control groups, respectively. Expression of p21ras and its regulatory elements, the GTPase activating protein p120ras-GAP and the guanine nucleotide releasing factor (GNRF) hSOS, was comparable in the three groups. The in vitro proliferative response to PHA was comparable in the IDDM and control groups: stimulation index (SI) of 8.6 +/- 2.5 and 9.4 +/- 3.5 respectively, p < 0.44. No correlations were found in the IDDM patients between the degree of p21ras activation and the mitogen induced in vitro proliferative response or the various clinical parameters including age, gender, disease duration, daily insulin requirements and metabolic control. Taken together these data indicate that PBMC from IDDM patients are characterized by a persistent impairment in the activation of their p21ras. They also suggest that p21ras stimulated activity is a sensitive and independent parameter of PBMC activation in these patients.

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