Background: Nucleic acid amplification enhancers suitable for use in a recombinase-aided amplification (RAA) assay were studied for the first time, and amplification of a long-fragment (509 bp) was initially explored.
Methods: Using recombinant plasmids and clinical samples, RAA fluorescence and basic methods were used to evaluate the efficacy. The fluorescence method was evaluated by threshold time and fluorescence value, and the basic method was characterized by 2% agarose gel electrophoresis.
Results: Taking a previously established RAA assay for HPV18 as an example, we demonstrated that the addition of 0.2 M, 0.4 M, and 0.6 M betaine and 10% pullulan could enhance the RAA. The new RAA assays with betaine and pullulan were named B-RAA and P-RAA, respectively. Using the B-RAA and P-RAA fluorescence methods, the threshold time values could be shortened by 1.72-2.32 minutes and 2.60 minutes, respectively, and the fluorescence values could be enhanced by 8847.25-9094.37 mv and 5250 mv, respectively. Using the basic method, the sensitivity could be increased 10-fold. We successfully amplified a long-fragment of 509 bp using a P-RAA assay with a sensitivity of 102 copies/µL (compared with 103 copies/µL in the RAA assay).
Conclusions: Thus, we concluded that betaine and pullulan are effective additives to enhance the sensitivity of RAA assays.
In human neurodegenerative diseases, neurons undergo axonal degeneration months to years before they die. Here, we developed a system modeling early degenerative events in Drosophila adult photoreceptor cells. Thanks to the stereotypy of their axonal projections, this system delivers quantitative data on sporadic and progressive axonal degeneration of photoreceptor cells. Using this method, we show that exposure of adult female flies to a constant light stimulation for several days overcomes the intrinsic resilience of R7 photoreceptors and leads to progressive axonal degeneration. This was not associated with apoptosis. We furthermore provide evidence that loss of synaptic integrity between R7 and a postsynaptic partner preceded axonal degeneration, thus recapitulating features of human neurodegenerative diseases. Finally, our experiments uncovered a role of postsynaptic partners of R7 to initiate degeneration, suggesting that postsynaptic cells signal back to the photoreceptor to maintain axonal structure. This model can be used to dissect cellular and circuit mechanisms involved in the early events of axonal degeneration, allowing for a better understanding of how neurons cope with stress and lose their resilience capacities.SIGNIFICANCE STATEMENT Neurons can be active and functional for several years. In the course of aging and in disease conditions leading to neurodegeneration, subsets of neurons lose their resilience and start dying. What initiates this turning point at the cellular level is not clear. Here, we developed a model allowing to systematically describe this phase. The loss of synapses and axons represents an early and functionally relevant event toward degeneration. Using the ordered distribution of Drosophila photoreceptor axon terminals, we assembled a system to study sporadic initiation of axon loss and delineated a role for non-cell-autonomous activity regulation in the initiation of axon degeneration. This work will help shed light on key steps in the etiology of nonfamilial cases of neurodegenerative diseases.
Objective: Caregiver stress from a child's diagnosis can impact a caregiver's ability to participate in treatment decisions, comply, and manage long-term illness. The aim of this study was to compare caregiver stress in children with craniosynostosis at diagnosis and postoperatively.
Methods: This prospective study included caregivers of pediatric patients with craniosynostosis receiving operative intervention. Demographics and Parenting Stress Index, Short Form (PSI-SF) and Pediatric Inventory for Parents (PIP) surveys at baseline (preoperatively) and 3 and 6 months postoperatively were completed. PSI-SF scores between 15 and 80 are considered normal, with > 85 being clinically significant and requiring follow-up. Higher PIP scores represent increased frequency and difficulty of stressful events due to the child's illness. Pairwise comparisons were performed using the Wilcoxon signed-rank test. Multivariate analysis was performed to assess for PSI-SF and PIP predictors.
Results: Of 106 caregivers (84% Caucasian), there were 62 mothers and 40 fathers. There were 68 and 45 responses at 3 and 6 months postoperatively, respectively. Regarding the baseline group, more than 80% were between 20 and 40 years of age and 58% had less than 2 years of college education. The median household income fell in the $45,001-$60,000 bracket. There was no significant difference between median baseline PSI-SF score (65, IQR 51-80) and those at 3 months (p = 0.45) and 6 months (p = 0.82) postoperatively. Both median PIP frequency (89 vs 74, p < 0.01) and difficulty (79 vs 71, p < 0.01) scores were lower at 3 months, although no significant difference was observed at 6 months (frequency: 95 vs 91, p = 0.67; difficulty: 82 vs 80, p = 0.34). Female sex, uninsured status, and open surgery type were all risk factors for higher parental stress.
Conclusions: Stress levels ranged from normal to clinically significant in the caregivers, with sex, uninsured status, and open repair predicting higher stress. Stress decreased at 3 months postoperatively before increasing at 6 months. Intervention targeting caregiver stress should be explored to maintain lower stress observed at 3 months after surgery.
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