Cell division modulates prion accumulation in cultured cells

The phenotypic effect of prions on host cells is influenced by the physical properties of the prion strain and its level of accumulation. In mammalian cell cultures, prion accumulation is determined by the interplay between de novo prion formation, catabolism, cell division, and horizontal cell-to-cell transmission. Understanding this dynamic enables the analytical modeling of protein-based heritability and infectivity. Here, we quantitatively measured these competing effects in a subline of neuroblastoma (N2a) cells and propose a concordant reaction mechanism to explain the kinetics of prion propagation. Our results show that cell division leads to a predictable reduction in steady-state prion levels but not to complete clearance. Scrapie-infected N2a cells were capable of accumulating different steady-state levels of prions, dictated partly by the rate of cell division. We also show that prions in this subline of N2a cells are transmitted primarily from mother to daughter cells, rather than horizontal cell-to-cell transmission. We quantitatively modeled our kinetic results based on a mechanism that assumes a subpopulation of prions is capable of self-catalysis, and the levels of this subpopulation reach saturation in fully infected cells. Our results suggest that the apparent effectiveness of antiprion compounds in culture may be strongly influenced by the growth phase of the target cells.     

The determination of the fetal D status from maternal plasma for decision making on Rh prophylaxis is feasible

BACKGROUND: Noninvasive fetal RHD genotyping might become a valuable tool in decision making on antenatal Rh prophylaxis, which is currently in routine practice for all D? pregnancies in several countries. This study provides a large‐scale validation study of this technology to address questions concerning feasibility and applicability of its introduction into clinical routine. STUDY DESIGN AND METHODS: Real‐time polymerase chain reaction (PCR) targeting RHD Exons 5 and 7 was applied for the detection of fetal‐specific RHD sequences in maternal plasma. A total of 1113 women in 6 to 32 weeks (median, Week 25) of pregnancy were recruited. All of them were serologically typed as D? according to current German guidelines. DNA was extracted via a spin‐column method and a novel automated approach using magnetic tips. Real‐time PCR results were compared with postnatal serology and discrepancies further elucidated by DNA sequencing from a newborn's buccal swab. RESULTS: Sensitivities of fetal RHD genotyping were 99.7 percent (spin columns) and 99.8 percent (magnetic tips), thus comparable with serology (99.5%). The detection of weak D variants was more reliable by real‐time PCR. Specificities of fetal RHD genotyping were 99.2 percent (spin columns) and 98.1 percent (magnetic tips), which is lower than serology (>99.7%). Automation achieved significantly higher yields of cell‐free fetal DNA. CONCLUSION: This prospective clinical trial revealed that routine determination of the fetal D status from maternal plasma is feasible. Noninvasive fetal RHD genotyping can be considered as sensitive as the traditional postnatal serologic assay.     

A refined pharmacophore identifies potent 4-amino-7-chloroquinoline-based inhibitors of the botulinum neurotoxin serotype A metalloprotease

We previously identified structurally diverse small molecule (non-peptidic) inhibitors (SMNPIs) of the botulinum neurotoxin serotype A (BoNT/A) light chain (LC). Of these, several (including antimalarial drugs) contained a 4-amino-7-chloroquinoline (ACQ) substructure and a separate positive ionizable amine component. The same antimalarials have also been found to interfere with BoNT/A translocation into neurons, via pH elevation of the toxin-mediated endosome. Thus, this structural class of small molecules may serve as dual-function BoNT/A inhibitors. In this study, we used a refined pharmacophore for BoNT/A LC inhibition to identify four new, potent inhibitors of this structural class (IC50's ranged from 3.2 to 17 muM). Molecular docking indicated that the binding modes for the new SMNPIs are consistent with those of other inhibitors that we have identified, further supporting our structure-based pharmacophore. Finally, structural motifs of the new SMNPIs, as well as two structure-based derivatives, were examined for activity, providing valuable information about pharmacophore component contributions to inhibition.     

Infantile bladder rupture during voiding cystourethrography

Bladder rupture is rare during infancy and most of reported cases had urethral obstruction or neurogenic bladder. We report two cases of infantile bladder rupture during voiding cystourethrography (VCUG). This report reinforces the criteria for proper VCUG imaging procedure. Consideration of expected bladder volume for body weight, and close monitoring of bladder pressure and injection speed could prevent such complications.     

Assessing the effects of body weight on subchondral bone formation with quantitative 18F-sodium fluoride PET

Annals of Nuclear Medicine - The aim of this study was to quantify subchondral bone remodeling in the elbows, hands, knees, and feet using volumetric and metabolic parameters derived from...