The pair potential of colloidal stars

We report on the construction of colloidal stars: 1 micrometer polystyrene beads grafted with a dense brush of 1 micrometer long and 10 nm wide semi-flexible filamentous viruses. The pair interaction potentials of colloidal stars are measured using an experimental implementation of umbrella sampling, a technique originally developed in computer simulations in order to probe rare events. The influence of ionic strength and grafting density on the interaction is measured. Good agreements are found between the measured interactions and theoretical predictions based upon the osmotic pressure of counterions.Comment: 5 pages, 3 figures. Changed conten

Association of IL-1beta gene polymorphism with cachexia from locally advanced gastric cancer

BACKGROUND: IL-1beta has been implicated in inflammatory episode. In view of the inflammatory nature of cancer cachexia, we determined the predictive value of IL-1B-31 T/C, -511 C/T, +3954 C/T and IL-1RN VNTR gene polymorphisms on the occurrence of cachexia associated with locally advanced gastric cancer. METHODS: The study included 214 patients and 230 healthy volunteers. Genomic DNA was prepared from peripheral blood leukocytes. Genotypes and allele frequencies were determined in patients and healthy controls using restriction fragment length polymorphism analysis of polymerase chain reaction products. RESULTS: The overall frequencies of IL-1B-31 T, -511 T, +3954 T and IL-1RN VNTR alleles in patients with locally advanced gastric cancer were all comparable with those in controls. No significant differences were found in the distribution of IL-1B-31 T, -511 T and IL-1RN VNTR between patients with cachexia and without. Patients with cachexia showed a significantly higher prevalence of IL-1B+3954 T allele than those without (P = 0.018). In a logistic regression analysis adjusted for actual weight, carcinoma location and stage, the IL-1B+3954 CT genotype was associated with an odds ratio of 2.512 (95% CI, 1.180 – 5.347) for cachexia. CONCLUSION: The IL-1B+3954 T allele is a major risk for cachexia from locally gastric cancer. Genetic factors studied are not likely to play an important role in the determination of susceptibility to locally advanced gastric cancer

Restoration of Contralateral Representation in the Mouse Somatosensory Cortex after Crossing Nerve Transfer

Avulsion of spinal nerve roots in the brachial plexus (BP) can be repaired by crossing nerve transfer via a nerve graft to connect injured nerve ends to the BP contralateral to the lesioned side. Sensory recovery in these patients suggests that the contralateral primary somatosensory cortex (S1) is activated by afferent inputs that bypassed to the contralateral BP. To confirm this hypothesis, the present study visualized cortical activity after crossing nerve transfer in mice through the use of transcranial flavoprotein fluorescence imaging. In naïve mice, vibratory stimuli applied to the forepaw elicited localized fluorescence responses in the S1 contralateral to the stimulated side, with almost no activity in the ipsilateral S1. Four weeks after crossing nerve transfer, forepaw stimulation in the injured and repaired side resulted in cortical responses only in the S1 ipsilateral to the stimulated side. At eight weeks after crossing nerve transfer, forepaw stimulation resulted in S1 cortical responses of both hemispheres. These cortical responses were abolished by cutting the nerve graft used for repair. Exposure of the ipsilateral S1 to blue laser light suppressed cortical responses in the ipsilateral S1, as well as in the contralateral S1, suggesting that ipsilateral responses propagated to the contralateral S1 via cortico-cortical pathways. Direct high-frequency stimulation of the ipsilateral S1 in combination with forepaw stimulation acutely induced S1 bilateral cortical representation of the forepaw area in naïve mice. Cortical responses in the contralateral S1 after crossing nerve transfer were reduced in cortex-restricted heterotypic GluN1 (NMDAR1) knockout mice. Functional bilateral cortical representation was not clearly observed in genetically manipulated mice with impaired cortico-cortical pathways between S1 of both hemispheres. Taken together, these findings strongly suggest that activity-dependent potentiation of cortico-cortical pathways has a critical role for sensory recovery in patients after crossing nerve transfer