Spinocerebellar ataxia type 17: Report of a family with reduced penetrance of an unstable Gln(49 )TBP allele, haplotype analysis supporting a founder effect for unstable alleles and comparative analysis of SCA17 genotypes

BACKGROUND: Spinocerebellar ataxia type 17 (SCA17), a neurodegenerative disorder in man, is caused by an expanded polymorphic polyglutamine-encoding trinucleotide repeat in the gene for TATA-box binding protein (TBP), a main transcription factor. Observed pathogenic expansions ranged from 43 – 63 glutamine (Gln) codons (Gln(43–63)). Reduced penetrance is known for Gln(43–48 )alleles. In the vast majority of families with SCA17 an expanded CAG repeat interrupted by a CAA CAG CAA element is inherited stably. RESULTS: Here, we report the first pedigree with a Gln(49 )allele that is a) not interrupted, b) unstable upon transmission, and c) associated with reduced penetrance or very late age of onset. The 76-year-old father of two SCA17 patients carries the Gln(49 )TBP allele but presents without obvious neurological symptoms. His children with Gln(53 )and Gln(52 )developed ataxia at the age of 41 and 50. Haplotype analysis of this and a second family both with uninterrupted expanded and unstable pathological SCA17 alleles revealed a common core genotype not present in the interrupted expansion of an unrelated SCA17 patient. Review of the literature did not present instability in SCA17 families with expanded alleles interrupted by the CAA CAG CAA element. CONCLUSION: The presence of a Gln(49 )SCA17 allele in an asymptomatic 76-year-old male reams the discussion of reduced penetrance and genotypes producing very late disease onset. In SCA17, uninterrupted expanded alleles of TBP are associated with repeat instability and a common founder haplotype. This suggests for uninterrupted expanded alleles a mutation mechanism and some clinical genetic features distinct from those alleles interrupted by a CAA CAG CAA element

Fully automized system for pollen concentration measurement in ambient air

For the first time a fully automated system for the analysis of pollen concentration in ambient air has been built and was successfully tested. Principle of operation, range of application and present status of performance are described. The technology used in the system has the potential for further applications in the analysis of other airborne particles

Feasibility of Pulse Oximetry Pre-discharge Screening Implementation for detecting Critical Congenital heart Lesions in newborns in a secondary level maternity hospital in the Western Cape, South Africa: The ‘POPSICLe’ study

Background. Early detection of critical congenital heart disease (CCHD) through newborn pulse oximetry (POx) screening is an effective strategy for reducing paediatric morbidity and mortality rates and has been adopted by much of the developed world. Objectives. To document the feasibility of implementing pre-discharge POx screening in well babies born at Mowbray Maternity Hospital, a busy government hospital in Cape Town, South Africa. Parent and staff acceptance was assessed.Methods. We conducted a prospective study of predischarge POx screening in one postnatal ward, following informed parental consent.Results. During the 4-month study period, 1 017 of 2 256 babies discharged (45.1%) were offered POx screening and 1 001 were screened; 94.0% of tests took <3 minutes to perform, 4.3% 3 - 5 minutes and 1.7% >5 minutes. Eighteen patients needed second screens and three required third screens. Only 3.1% protocol errors were made, all without consequence. The vast majority (91.6%) of nursing staff reported insufficient time to perform the study screening in addition to their daily tasks, but ~75% felt that with a full nursing staff complement and if done routinely (not part of a study), pre-discharge POx screening could be successfully instituted at our facility. Over 98% of the mothers had positive comments. Two babies failed screening and required echocardiograms; one was diagnosed with CCHD and the other with neonatal sepsis. The sensitivity and specificity were 50% (95% confidence interval (CI) 1.3 - 98.7%) and 99.9% (95% CI 99.4 - 100%), respectively, with a percentage correct of 99.8%.Conclusions. POx screening was supported and accepted by staff and parents. If there are no nursing staff shortages and if it is done routinely before discharge, not as part of a study, we conclude that POx screening could be implemented successfully without excessive false positives or errors, or any additional burden to cardiology services

Safety of streptococcus pyogenes vaccines: anticipating and overcoming challenges for clinical trials and post marketing monitoring

Streptococcus. pyogenes (Strep A) infections result in a vastly underestimated burden of acute and chronic disease globally. The Strep A Vaccine Global Consortium (SAVAC) mission is to accelerate the development of safe, effective and affordable S. pyogenes vaccines. The safety of vaccine recipients is of paramount importance. A single S. pyogenes vaccine clinical trial conducted in the 1960s raised important safety concerns. A SAVAC Safety Working Group was established to review the safety assessment methodology and results of more recent early phase clinical trials and to consider future challenges for vaccine safety assessments across all phases of vaccine development. No clinical or biological safety signals were detected in any of these early phase trials in the modern era. Improvements in vaccine safety assessments need further consideration, particularly for pediatric clinical trials, large-scale efficacy trials, and preparation for post-marketing pharmacovigilance

Rem2-Targeted shRNAs Reduce Frequency of Miniature Excitatory Postsynaptic Currents without Altering Voltage-Gated Ca2+ Currents

Ca2+ influx through voltage-gated Ca2+ channels (VGCCs) plays important roles in neuronal cell development and function. Rem2 is a member of the RGK (Rad, Rem, Rem2, Gem/Kir) subfamily of small GTPases that confers potent inhibition upon VGCCs. The physiologic roles of RGK proteins, particularly in the brain, are poorly understood. Rem2 was implicated in synaptogenesis through an RNAi screen and proposed to regulate Ca2+ homeostasis in neurons. To test this hypothesis and uncover physiological roles for Rem2 in the brain, we investigated the molecular mechanisms by which Rem2 knockdown affected synaptogenesis and Ca2+ homeostasis in cultured rat hippocampal neurons. Expression of a cocktail of shRNAs targeting rat Rem2 (rRem2) reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) measured 10 d after transfection (14 d in vitro), but did not affect mEPSC amplitude. VGCC current amplitude after rRem2-targeted knockdown was not different from that in control cells, however, at either 4 or 10 d post transfection. Co-expression of a human Rem2 that was insensitive to the shRNAs targeting rRem2 was unable to prevent the reduction in mEPSC frequency after rRem2-targeted knockdown. Over-expression of rRem2 resulted in 50% reduction in VGCC current, but neither the mEPSC frequency nor amplitude was affected. Taken together, the observed effects upon synaptogenesis after shRNA treatment are more likely due to mechanisms other than modulation of VGCCs and Ca2+ homeostasis, and may be independent of Rem2. In addition, our results reveal a surprising lack of contribution of VGCCs to synaptogenesis during early development in cultured hippocampal neurons

Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Cav1.3 channels

Ca2+/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca2+ channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within CaV1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a “hinged lid–shield” mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a “shield” in CaV1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca2+ channelopathies involving S6 mutations