Biostructural analysis of the metal-sensor domain of CnrX from <Emphasis Type="Italic">Cupriavidus metallidurans</Emphasis> CH34

In Cupriavidus metallidurans CH34, the proteins CnrX, CnrY, and CnrH regulate the expression of the cnrCBA operon that codes for a cation-efflux pump involved in cobalt and nickel resistance. The periplasmic part of CnrX can be defined as the metal sensor in the signal transduction complex composed of the membrane-bound anti-sigma factor CnrY and the extra-cytoplasmic function sigma factor CnrH. A soluble form of CnrX was overproduced and purified. This protein behaves as a dimer in solution as judged from gel filtration, sedimentation velocity experiments, and NMR. Native crystals diffracting to 2.3 A using synchrotron radiation were obtained using the hanging-drop vapor-diffusion method. They belong to the primitive monoclinic space group P2(1), with unit cell parameters a = 31.87, b = 74.80, c = 93.67 A, beta = 90.107 degrees. NMR data and secondary structure prediction suggest that this protein is essentially formed by helices.     

Acquired resistance in dogs to repeated infestation with Ixodes scapularis (Acari: Ixodidae) reduces tick viability and reproductive success

The purpose of this study was to determine whether dogs develop acquired resistance to adult Ixodes scapularis infestation in an experimental model. Five dogs were each infested with ten mating pairs of ticks every week for 7 consecutive weeks, another five dogs were each infested with ten mating pairs once every 2 weeks for 10 weeks and four dogs served as controls not exposed to ticks. All ticks were allowed to feed to repletion and were collected only after dropping from the host. Several variables were measured to determine the extent of blood feeding success. Regression analysis indicated that the engorgement success, survival and mean tick engorgement weight declined with repeated infestation in both groups of dogs (p<0.05). Tick oviposition as well as the F1 viability declined with each successive infestation in both groups. These results suggest that repeated infestation with I. scapularis elicits a protective immune response against tick feeding and could serve as a limiting factor in the spread and transmission of Borrelia burgdorferi.     

Observations on the morphology of submaxillary gland cells isolated in a density gradient,and the demonstration of interacinar bridges

Summary Methods are presented for the recovery of separate fractions of rabbit submaxillary acinar and striated duct cells from acini and duct segments, by means of density gradient centrifugation in glycerol-sucrose mixtures.Incomplete acinar fragmentation discloses the presence of acellular, nonstaining interacinar structures, referred to as interacinar bridges. The effectiveness of trypsin in liberating the acinar cells is ascribed to the disruption of intercellular secretory capillaries and interacinar bridges.The basal processes of the isolated striated duct cells correspond with both the striations observed with optical microscopy and the infolded cytoplasmic compartments revealed with electron microscopy. The presence of clearly discernible spaces between the basal processes is compatible with the concept of intermembrane dilations.     

Biosynthesis of calystegines: 15N NMR and kinetics of formation in root cultures of Calystegia sepium

Calystegines are nortropane alkaloids bearing between three and five hydroxyl groups in various positions. [15N]Tropinone was administered to root cultures of Calystegia sepium and the incorporation into calystegines was followed. Increase of label in calystegines was measured by one-dimensional 15N NMR and inverse-detected 2D NMR techniques. The results show that tropinone and pseudotropine are metabolites in the biosynthetic pathway of calystegines. The velocity of calystegine accumulation was followed kinetically by transfer of root cultures from 15N-enriched medium to 14N-medium and analysis by GC-MS. A constant calystegine formation with no interference by excretion or degradation was observed. A biosynthetic rate for individual calystegines at each time point was calculated, the maximum was 0.4 mg/day/g of biomass. This allowed the velocity of individual biosynthetic steps to be estimated.     

La fertilité chez le blessé médullaire. Effet du niveau de la lésion médullaire

The majority of spinal cord injured males cannot procreate naturally due to anejaculation as well as abnormal sperm characteristics. Treatment of this impaired fertility must be associated with treatment of neurogenic urinary tract disorders, bowel dysfunction and spasticity. The level of the spinal lesion and the spinal cord injury syndrome influence the possibility of inducing reflex ejaculation by penile vibratory stimulation and sperm quality.     

Shape analysis of tumor cell nuclei in ependymomas by means of Fourier analysis

OBJECTIVE: To study the prognostic significance of nuclear shape analysis in ependymomas. STUDY DESIGN: Tumor cell nuclei in surgical specimens of primary resected ependymomas from 30 patients were evaluated by means of Fourier analysis of nuclear contours, conventional morphometric features (nuclear area, shape factor) and the Ki-67 proliferation index. Fourier analysis can be used for decomposing an irregular nuclear contour by calculating "Fourier amplitudes." Tumors with different tumor grades according to the World Health Organization were compared, as were patients with and without recurrence of ependymomas. Planimetric data were further correlated with the Ki-67 index. RESULTS: t Test and multivariate analysis showed distinct differences between ependymomas with tumor grade 3 and the other tumor grades. Cross-validated, stepwise discriminant analysis with the event of recurrence as grouping variable revealed correct reclassification in 16/18 cases without recurrence and of 10/12 cases with recurrence. When considering just intracranial ependymomas with total surgical removal, Fourier amplitudes provided 100% correct reclassification concerning recurrence. Proliferation index, in contrast, showed considerable overlap between all tumor grades and between cases with and without recurrence. CONCLUSION: Quantification of the shape of tumor cell nuclei in ependymomas by means of Fourier analysis has prognostic significance and seems to be superior to the Ki-67 index.