A diamond-detector-based fast-particle spectrometer with digital signal processing

A spectrometer with digital signal processing is intended to make measurements at counting rates that are at least an order of magnitude higher than the limiting counting rate of an analog spectrometer. The tests have shown that the spectrometer operating in the maximum count rate mode compares well with the traditional analog spectrometer in such important characteristics as energy resolution, linearity, and noise immunity. The pilot version of the designed digital spectrometer was successfully used on the JET tokamak for recording energy distributions of fast charge exchange atoms with energies above 40 keV.     

Neutron analysis of the ITER vertical neutron camera

The neutron fields in the collimators of a new design for the vertical neutron camera (VNC) of the ITER have been calculated for a standard isotropic bulk DT neutron source. The neutron and gamma-ray spectra and flux densities at the neutron detector sites have been calculated. The signal-to-background ratio of VNC detectors (²³⁸U-based fission chambers and diamond detectors) has been estimated. The signal-to-background ratios versus the threshold energy were calculated for the diamond detectors operating in the threshold counter mode. The effect of background Γ-ray radiation on the performance of the diamond detectors in the VNC environment has been estimated. The radiation heating of the VNC structural components has been calculated. The serviceability of the VNC with the proposed design has been demonstrated.     

Relationship between dopamine agonist stimulation of inositol phosphate formation and cytidine diphosphate-diacylglycerol accumulation in brain slices

Dopamine receptor-coupled stimulation of inositol phosphate formation has been characterized extensively, but little is known about the diacylglycerol arm of this dual-signaling pathway. This study examined several parameters of cytidine diphosphate-diacylglycerol (CDP-DG) accumulation as an index of agonist-stimulated DG formation. Rat brain slices pre-labeled with 5-[3H]cytidine were incubated with various test agents in the presence of LiCl and accumulated CDP-DG analyzed. Dopamine and SKF38393 significantly and dose-dependently stimulated CDP-DG accumulation. SKF38393 responses were inhibited by neomycin and reversed by myo-inositol or by exclusion of LiCl. Compared to inositol phosphate formation in 2-[3H]inositol-prelabeled slices, the CDP-DG responses were proportionately greater, while the agonist EC50 values were similar between the two assays. The D1-receptor antagonist SCH23390 inhibited SKF38393-mediated responses at 0.1-10 microM concentrations, whereas greater concentrations reversed the inhibition. SKF38393 effects were completely blocked by the DG kinase inhibitor R59022, thus precluding any role for phospholipase-D or de novo phosphatidate synthesis in the dopaminergic response. D609 which inhibits phosphatidylcholine-specific phospholipase-C (PLC), potently inhibited both CDP-DG accumulation and inositol phosphate formation. These findings demonstrate that the selective D1-receptor antagonist SCH23390 is a partial agonist at the D1-like dopamine receptor that couples to phosphoinositide signaling, that dopaminergic facilitation of phosphoinositide signaling is independent of de novo phosphatidate synthesis, and that the widely used enzyme inhibitor, D-609, is probably not selective for phosphatidylcholine-specific PLC in brain slice preparations. The greater sensitivity of the CDP-DG measurement presents this assay as a reliable and possibly superior index of dopamine receptor-coupled PLC activation in intact tissues.     

The cholecystokinin-A receptor mediates inhibition of food intake yet is not essential for the maintenance of body weight

Food intake and body weight are determined by a complex interaction of regulatory pathways. To elucidate the contribution of the endogenous peptide cholecystokinin, mice lacking functional cholecystokinin-A receptors were generated by targeted gene disruption. To explore the role of the cholecystokinin-A receptor in mediating satiety, food intake of cholecystokinin-A receptor-/- mice was compared with the corresponding intakes of wild-type animals and mice lacking the other known cholecystokinin receptor subtype, cholecystokinin-B/gastrin. Intraperitoneal administration of cholecystokinin failed to decrease food intake in mice lacking cholecystokinin-A receptors. In contrast, cholecystokinin diminished food intake by up to 90% in wild-type and cholecystokinin-B/gastrin receptor-/- mice. Together, these findings indicate that cholecystokinin-induced inhibition of food intake is mediated by the cholecystokinin-A receptor. To explore the long-term consequences of either cholecystokinin-A or cholecystokinin-B/gastrin receptor absence, body weight as a function of age was compared between freely fed wild-type and mutant animals. Both cholecystokinin-A and cholecystokinin-B/gastrin receptor-/- mice maintained normal body weight well into adult life. In addition, each of the two receptor-/- strains had normal pancreatic morphology and were normoglycemic. Our results suggest that although cholecystokinin plays a role in the short-term inhibition of food intake, this pathway is not essential for the long-term maintenance of body weight.     

Cesarean section scar as a cause of abnormal vaginal bleeding: diagnosis by sonohysterography

A previously undescribed cause of abnormal uterine bleeding is presented. Nine of 310 women evaluated by sonohysterography for abnormal bleeding demonstrated an 8 to 17 mm gap in the anterior lower uterine segment myometrium at the site of prior cesarean deliveries. All women were premenopausal and had a history of 2 to 12 days of postmenstrual spotting. Presumably a lack of coordinated muscular contractions occurs around the cesarean scar, allowing the defect to collect menstrual debris. Subsequently, the debris leaches out through the cervix for several days after the majority of menstrual flow has ceased.