Legionella pneumophila NudA Is a Nudix hydrolase and virulence factor

We studied the identity and function of the 528-bp gene immediately upstream of Legionella pneumophila F2310 ptsP (enzyme I(Ntr)). This gene, nudA, encoded for a Nudix hydrolase based on the inferred protein sequence. NudA had hydrolytic activity typical of other Nudix hydrolases, such as Escherichia coli YgdP, in that Ap(n)A's, in particular diadenosine pentaphosphate (Ap(5)A), were the preferred substrates. NudA hydrolyzed Ap(5)A to ATP plus ADP. Both ptsP and nudA were cotranscribed. Bacterial two-hybrid analysis showed no PtsP-NudA interactions. Gene nudA was present in 19 of 20 different L. pneumophila strains tested and in 5 of 10 different Legionella spp. other than L. pneumophila. An in-frame nudA mutation was made in L. pneumophila F2310 to determine the phenotype. The nudA mutant was an auxotroph that grew slowly in liquid and on solid media and had a smaller colony size than its parent. In addition, the mutant was more salt resistant than its parent and grew very poorly at 25 degrees C; all of these characteristics, as well as auxotrophy and slow-growth rate, were reversed by transcomplementation with nudA. The nudA mutant was outcompeted by about fourfold by the parent in competition studies in macrophages; transcomplementation almost completely restored this defect. Competition studies in guinea pigs with L. pneumophila pneumonia showed that the nudA mutant was outcompeted by its parent in both lung and spleen. NudA is of major importance for resisting stress in L. pneumophila and is a virulence factor.     

Performance of seven consumer sleep-tracking devices compared with polysomnography

Study ObjectivesConsumer sleep-tracking devices are widely used and becoming more technologically advanced, creating strong interest from researchers and clinicians for their possible use as alternatives to standard actigraphy. We, therefore, tested the performance of many of the latest consumer sleep-tracking devices, alongside actigraphy, versus the gold-standard sleep assessment technique, polysomnography (PSG).MethodsIn total, 34 healthy young adults (22 women; 28.1 ± 3.9 years, mean ± SD) were tested on three consecutive nights (including a disrupted sleep condition) in a sleep laboratory with PSG, along with actigraphy (Philips Respironics Actiwatch 2) and a subset of consumer sleep-tracking devices. Altogether, four wearable (Fatigue Science Readiband, Fitbit Alta HR, Garmin Fenix 5S, Garmin Vivosmart 3) and three nonwearable (EarlySense Live, ResMed S+, SleepScore Max) devices were tested. Sleep/wake summary and epoch-by-epoch agreement measures were compared with PSG.ResultsMost devices (Fatigue Science Readiband, Fitbit Alta HR, EarlySense Live, ResMed S+, SleepScore Max) performed as well as or better than actigraphy on sleep/wake performance measures, while the Garmin devices performed worse. Overall, epoch-by-epoch sensitivity was high (all ≥0.93), specificity was low-to-medium (0.18–0.54), sleep stage comparisons were mixed, and devices tended to perform worse on nights with poorer/disrupted sleep.ConclusionsConsumer sleep-tracking devices exhibited high performance in detecting sleep, and most performed equivalent to (or better than) actigraphy in detecting wake. Device sleep stage assessments were inconsistent. Findings indicate that many newer sleep-tracking devices demonstrate promising performance for tracking sleep and wake. Devices should be tested in different populations and settings to further examine their wider validity and utility.     

Infections in the diabetic host

The presence of the diabetic state seems to predispose patients to more severe and unusual types of infections. Awareness and early recognition of these sometimes devastating problems, coupled with appropriate medical and surgical treatment and aggressive metabolic control of diabetes, provide the maximum opportunity for healing and recovery.     

Are computed tomography scans adequate in assessing cervical spine pain following blunt trauma?

Good quality three-view radiographs (anteroposterior, lateral, and open-mouth/odontoid) of the cervical spine exclude most unstable injuries, with sensitivity as high as 92% in adults and 94% in children. The diagnostic performance of helical computed tomography (CT) scanners may be even greater, with reported sensitivity as high as 99% and specificity 93%. Missed injuries are usually ligamentous, and may only be detected with magnetic resonance imaging (MRI) or dynamic plain radiographs. With improvements in the accessibility of advanced imaging (helical CT and MRI) and with improvements in the resolution of such imaging, dynamic screening is now used less commonly to screen for unstable injuries. This case involves a patient with an unstable cervical spine injury whose cervical subluxation was only detected following use of dynamic radiographs, despite a prior investigation with helical CT. In this way, the use of dynamic radiographs following blunt cervical trauma should be considered an effective tool for managing acute cervical spine injury in the awake, alert, and neurologically intact patient with neck pain.     

Reuse of disposable syringe-needle units in the diabetic patient

A comparison was made between reuse of plastic disposable needle-syringe units and glass syringes with daily new needles in diabetic patients who take daily insulin injections. Parameters studied were incidence of infection, clarity of syringe readings, ability to use syringe, and sharpness of needle. The plastic disposable units could be reused with safety and patient satisfaction by most patients for at least 3 days. Considerable cost benefit could accrue if disposable units were used more than one time for insulin injections.