38 research outputs found
Experience with use of extended length peritoneal shunt catheters
Journal ArticleThe placement of a ventriculoperitoneal (VP) shunt is the current treatment of choice for diversion of cerebrospinal fluid associated with hydrocephalus. Although there are a host of reported potential abdominal complications related to the procedure, they are notably uncommon. The authors report their experience with the primary insertion of an extended length open-ended peritoneal tubing (120 cm) undertaken expressly to avoid the need for a lengthening procedure because of growth of the patient. In a review of new insertions of VP shunts using the extended length tubing over a 14-year period at Childrens Hospital of Los Angeles, a total of 998 shunts were placed in 952 patients, with a mean follow-up period of 6.7 years. The patients experienced a total of 52 distal shunt revisions for a variety of malfunction etiologies. In patients ranging in age from premature neonate to 20 years, there was no increase in the distal complication rate, and specifically no complications were experienced that were directly related to the use of the extended length tubing. The authors conclude that the use of an extended length peritoneal shunt catheter is not associated with an increase in complications and eliminates the need to lengthen the peritoneal catheter for growth of the patient
Novel Riboswitch Ligand Analogs as Selective Inhibitors of Guanine-Related Metabolic Pathways
Riboswitches are regulatory elements modulating gene expression in response to specific metabolite binding. It has been recently reported that riboswitch agonists may exhibit antimicrobial properties by binding to the riboswitch domain. Guanine riboswitches are involved in the regulation of transport and biosynthesis of purine metabolites, which are critical for the nucleotides cellular pool. Upon guanine binding, these riboswitches stabilize a 5′-untranslated mRNA structure that causes transcription attenuation of the downstream open reading frame. In principle, any agonistic compound targeting a guanine riboswitch could cause gene repression even when the cell is starved for guanine. Antibiotics binding to riboswitches provide novel antimicrobial compounds that can be rationally designed from riboswitch crystal structures. Using this, we have identified a pyrimidine compound (PC1) binding guanine riboswitches that shows bactericidal activity against a subgroup of bacterial species including well-known nosocomial pathogens. This selective bacterial killing is only achieved when guaA, a gene coding for a GMP synthetase, is under the control of the riboswitch. Among the bacterial strains tested, several clinical strains exhibiting multiple drug resistance were inhibited suggesting that PC1 targets a different metabolic pathway. As a proof of principle, we have used a mouse model to show a direct correlation between the administration of PC1 and the reduction of Staphylococcus aureus infection in mammary glands. This work establishes the possibility of using existing structural knowledge to design novel guanine riboswitch-targeting antibiotics as powerful and selective antimicrobial compounds. Particularly, the finding of this new guanine riboswitch target is crucial as community-acquired bacterial infections have recently started to emerge
The rise and fall of the king : the correlation between FO Aquarii's low states and the White Dwarf's Spindown
The intermediate polar FO Aquarii experienced its first-reported low-accretion states in 2016, 2017, and 2018. We establish that these low states occurred shortly after the system's white dwarf (WD) began spinning down, after having spent a quarter-century spinning up. FO Aquarii is the only intermediate polar whose period derivative has undergone a sign change, and it has now done so twice. By combining our spin-pulse timings with previous data, we determine that the WD's spin period has varied quasi-sinusoidally since the system's discovery, and an extrapolation predicts that the white dwarf was spinning down during newly discovered low states in photographic plates from 1964, 1965, and 1974. Thus, FO Aquarii's low states appear to occur exclusively during epochs of spindown. Additionally, our time-series photometry of the 2016-18 low states reveals that the mode of accretion is extremely sensitive to the accretion rate; when the system is fainter than V~14.0, the accretion onto the WD is largely stream-fed, but when it is brighter, it is almost exclusively disk-fed. The system's grazing eclipse remained detectable throughout all observations, confirming the uninterrupted presence of a disk-like structure, regardless of the accretion state. Our observations are consistent with theoretical predictions that during the low states, the accretion disk dissipates into a ring of diamagnetic blobs. Finally, a new XMM-Newton observation from 2017 indicates that the system's anomalously soft X-ray spectrum and diminished X-ray luminosity in the wake of the 2016 low state appear to be long-lasting changes compared to pre-2016 observations.peer-reviewe
Sensory Communication
Contains table of contents for Section 2, an introduction and reports on twelve research projects.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R01-DC00270U.S. Air Force - Office of Scientific Research Contract AFOSR-90-0200National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Training Systems Center Contract N61339-93-M-1213U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0055U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0083U.S. Navy - Office of Naval Research Grant N00014-92-J-4005U.S. Navy - Office of Naval Research Grant N00014-93-1-119
Sensory Communication
Contains table of contents for Section 2 and reports on five research projects.National Institutes of Health Contract 2 R01 DC00117National Institutes of Health Contract 1 R01 DC02032National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Contract N01 DC22402National Institutes of Health Grant R01-DC001001National Institutes of Health Grant R01-DC00270National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Air Warfare Center Training Systems Division Contract N61339-94-C-0087U.S. Navy - Naval Air Warfare Center Training System Division Contract N61339-93-C-0055U.S. Navy - Office of Naval Research Grant N00014-93-1-1198National Aeronautics and Space Administration/Ames Research Center Grant NCC 2-77
Trust in government regarding COVID-19 and its associations with preventive health behaviour and prosocial behaviour during the pandemic: a cross-sectional and longitudinal study
Background. The effective implementation of government policies and measures for controlling the coronavirus disease 2019 (COVID-19) pandemic requires compliance from the public. This study aimed to examine cross-sectional and longitudinal associations of trust ingovernment regarding COVID-19 control with the adoption of recommended health behaviours and prosocial behaviours, and potential determinants of trust in government duringthe pandemic.Methods. This study analysed data from the PsyCorona Survey, an international project onCOVID-19 that included 23 733 participants from 23 countries (representative in age andgender distributions by country) at baseline survey and 7785 participants who also completedfollow-up surveys. Specification curve analysis was used to examine concurrent associationsbetween trust in government and self-reported behaviours. We further used structural equation model to explore potential determinants of trust in government. Multilevel linear regressions were used to examine associations between baseline trust and longitudinal behavioural changes.Results. Higher trust in government regarding COVID-19 control was significantly associatedwith higher adoption of health behaviours (handwashing, avoiding crowded space, self-quarantine) and prosocial behaviours in specification curve analyses (median standardised β =0.173 and 0.229, p < 0.001). Government perceived as well organised, disseminating clear messages and knowledge on COVID-19, and perceived fairness were positively associated withtrust in government (standardised β = 0.358, 0.230, 0.056, and 0.249, p < 0.01). Higher trustat baseline survey was significantly associated with lower rate of decline in health behavioursover time ( p for interaction = 0.001).Conclusions. These results highlighted the importance of trust in government in the control of Covid-19
Malignant transformation of recurrent meningioma with pulmonary metastases
A patient presented with a histologically benign intracranial meningioma which, after multiple recurrences, underwent malignant transformation. The patient survived 18 years following initial presentation. Pulmonary metastases were present over the final 8 years. Eleven subtotal resections of the meningioma were performed, including exenteration of the right eye and a thoracotomy. Radiation therapy and chemotherapy were relatively ineffective. The problem and treatment of recurrent meningiomas is briefly reviewed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27950/1/0000380.pd
An Analysis of the Open Architecture Warfare System Domain Model for surface time critical targets
This study's objective is to evaluate the Open Architecture Warfare System Domain Model (OAWSDM) against time critical targets with specific focus on command, control, and communication processes. A functional analysis of the OAWSDM was conducted and synthesized to create the Open Architecture Time Critical Target Engagement Process Model (OATCTEPM). This model represents the notional engagement cycle of a Navy cruiser. Two scenarios were developed to exercise the system: a surprise assault from a number of personal watercraft and a saturation assault in which approximately fifty craft of varying sizes attack. Results from these scenarios were analyzed for system bottlenecks and recommendations were made to improve decision making processes and reduce engagement time. This study concludes that while the OAWSDM may offer no technical flaws in its design, it fails to factor in the role of the human in the decision making and engagement processes. In doing so it overlooks a key factor in the effectiveness of the architecture against surface TCT engagements.http://archive.org/details/ananalysisofopen109456933N
Application aspects of multiterminal DC power transmission
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[beta]-Hydroxybutyrate and response to hypoxia in the ground squirrel, Spermophilus tridecimlineatus
1. 1. Previous studies have suggested that elevated ketone levels are associated with increased survival time in rodents exposed to hypoxia. In this study the association between whole blood BHB ([beta]-hydroxybutyrate) and hypoxic surivaval time was investigated in hibernating and non-hibernating ground squirrels and in rats.2. 2. Non-hibernating ground squirrels and rats were exposed to hypoxia (4.5% O2). One hundred per cent of ground squirrels survived 1 hr of hypoxia vs 20% of rats.3. 3. Ketone levels were significantly higher in ground squirrels than rats during hypoxia, and rats surviving the longest had the highest ketone levels. 4. When hibernation was induced in ground squirrels there was a significant increase in [beta]-hydroxybutyrate from 0.45 to 1.6 mM (P = 0.0005).4. 5. Ground squirrel heart mitochondrial respiratory control ratios and ATP synthesis rates indicated no preferential ketone utilization which might suggest a possible extramitochondrial role of BHB during hypoxia.5. 6. We conclude that elevated blood BHB levels are associated with increased hypoxic survival and they may have evolved in response to life-threatening hypoxia as experienced during hibernation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28833/1/0000668.pd