The effect of respiratory activity,non-invasive respiratory support and facemasks on aerosol generation and its relevance to COVID-19

Respirable aerosols (< 5 µm in diameter) present a high risk of SARS-CoV-2 transmission. Guidelines recommend using aerosol precautions during aerosol-generating procedures, and droplet (> 5 µm) precautions at other times. However, emerging evidence indicates respiratory activities may be a more important source of aerosols than clinical procedures such as tracheal intubation. We aimed to measure the size, total number and volume of all human aerosols exhaled during respiratory activities and therapies. We used a novel chamber with an optical particle counter sampling at 100 l.min^-1 to count and size-fractionate close to all exhaled particles (0.5–25 µm). We compared emissions from ten healthy subjects during six respiratory activities (quiet breathing; talking; shouting; forced expiratory manoeuvres; exercise; and coughing) with three respiratory therapies (high-flow nasal oxygen and single or dual circuit non-invasive positive pressure ventilation). Activities were repeated while wearing facemasks. When compared with quiet breathing, exertional respiratory activities increased particle counts 34.6-fold during talking and 370.8-fold during coughing (p < 0.001). High-flow nasal oxygen 60 at l.min^-1 increased particle counts 2.3-fold (p = 0.031) during quiet breathing. Single and dual circuit non-invasive respiratory therapy at 25/10 cm.H₂O with quiet breathing increased counts by 2.6-fold and 7.8-fold, respectively (both p < 0.001). During exertional activities, respiratory therapies and facemasks reduced emissions compared with activities alone. Respiratory activities (including exertional breathing and coughing) which mimic respiratory patterns during illness generate substantially more aerosols than non-invasive respiratory therapies, which conversely can reduce total emissions. We argue the risk of aerosol exposure is underappreciated and warrants widespread, targeted interventions.     

Should surgeons repair symptomatic,clinically occult,radiologically evident,inguinal hernias? A case–control study of patient-reported outcomes

Hernia - Patients who present with symptomatic, clinically occult, radiologically evident (SCORE) inguinal hernia represent diagnostic and therapeutic challenge with a wide differential diagnosis...     

Comparison of local influenza vaccine effectiveness using two methods

BackgroundIn some settings, research methods to determine influenza vaccine effectiveness (VE) may not be appropriate because of cost, time constraints, or other factors. Administrative database analysis of viral testing results and vaccination history may be a viable alternative. This study compared VE estimates from outpatient research and administrative databases.MethodsUsing the test-negative, case-control design, data for 2017–2018 and 2018–2019 influenza seasons were collected using: 1) consent, specimen collection, RT-PCR testing and vaccine verification using multiple methods; and 2) an administrative database of outpatients with a clinical respiratory viral panel combined with electronic immunization records. Odds ratios for likelihood of influenza infection by vaccination status were calculated using multivariable logistic regression. VE = (1 ? aOR) × 100.ResultsResearch participants were significantly younger (P < 0.001), more often white (69% vs. 59%; P < 0.001) than non-white and less frequently enrolled through the emergency department (35% vs. 72%; P < 0.001) than administrative database participants. VE was significant against all influenza and influenza A in each season and both seasons combined (37–49%). Point estimate differences between methods were evident, with higher VE in the research database, but insignificant due to low sample sizes. When enrollment sites were separately analyzed, there were significant differences in VE estimates for all influenza (66% research vs. 46% administrative P < 0.001) and influenza A (67% research vs. 49% administrative; P < 0.001) in the emergency department.Conclusions:The selection of the appropriate method for determining influenza vaccine effectiveness depends on many factors, including sample size, subgroups of interest, etc., suggesting that research estimates may be more generalizable. Other advantages of research databases for VE estimates include lack of clinician-related selection bias for testing and less misclassification of vaccination status. The advantages of the administrative databases are potentially shorter time to VE results and lower cost.     

Enzyme kinetics and relaxation measurements with surface coils

A pulse sequence which produces the inversion of magnetization at a selected chemical shift for in vivo surface coil spectroscopy is proposed. The sequence uses a shaped, complex sech inversion pulse and "depth pulse" phase alternation. The sequence can be used for both in vivo inversion transfer and inversion recovery experiments.     

Regeneration in vitro of axolotl peripheral and central axons

Peripheral nerves and spinal cords of axolotls were maintained in organ culture for periods of up to 2 weeks. Sensory axons in peripheral nerves and the dorsal funiculus of the spinal cord showed regeneration through the crush site within about 2 days. Axonal regeneration also occurred in peripheral nerves after cutting but was dependent on close contact between proximal and distal stumps of nerve. When cells in the distal stump of nerve were killed by freezing, axonal regeneration was inhibited.     

The role of individualized care in a service delivery system for children and adolescents with severely maladjusted behavior

Individualized care is a total system of care that is tailored to a child with severely maladjusted behavior. The services are unconditional, flexible, child and family focused, and interagency coordinated. The services follow the child until the child is adjusting in a normalized, mainstream environment. Individualized care is illustrated through two different projects. One is the Alaska Youth Initiative where individualized care was used to return children from out-of-state, residential programs. The other is Project Wraparound where it was used to prevent children from being removed from their families. This paper begins with the principles of individualized care and then describes the ecological, multilevel assessment process that coincides with the delivery of services. A case example from Project Wraparound is provided for clarification. Following the case example is a discussion of the need for evaluation data with some suggested strategies for documenting effectiveness. The final section focuses on two barriers to the implementation of individualized care. One is the tendency to think in terms of component programs rather than individualized services. The other barrier is the competition for scarce resources. Strategies are presented for overcoming both barriers.     

Induction of chorea and dystonia in parkinsonian primates

Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in primates induced a parkinsonian syndrome that could be reversed by levodopa treatment. Animals quickly developed an apparent restlessness ("akathisia") of the lower limbs after as little as five doses. After 4-10 weeks of regular levodopa therapy, animals developed "peak dose" choreiform movements in the lower limbs that spread, with time, to involve the upper limbs and orofacial musculature. With further treatment (5-21 months), animals developed "peak dose" dystonia that variably involved the limbs and orofacial musculature. These conditions represent novel models of levodopa-induced chorea and dystonia in humans. They depend on the same underlying neuropathology and treatment regimen as their human counterparts. It is to be anticipated that these models of dyskinesia will be useful in determining the mechanisms underlying chorea and dystonia in humans and are ideally suited for experimental evaluation of new treatment strategies.     

Sites of [3H]taurine Uptake in the Rat Substantia Nigra in Relation to the Release of Taurine from the Striatonigral Pathway

The autoradiographic localization of radiolabelled taurine taken up in the rat substantia nigra in vivo together with conditions of release of the [3H]taurine taken up into brain slices were studied to determine whether they are consistent with the hypothesis that taurine may act as a neurotransmitter in the striatonigral pathway. At the light microscopic level the main cellular elements that became radiolabelled following the injection of [3H]taurine into the substantia nigra could be identified as glial cells. Electron microscope autoradiography confirmed that a subpopulation of glial cells including astrocytes, pericytes, and oligodendrocytes were radiolabelled and that neuronal perikarya were not radiolabelled. In addition, axonal elements including both terminal and preterminal boutons were found to have silver grains overlying them and were thus considered to be radiolabelled. This was supported by a quantitative analysis of the distribution of the silver grains; whereas glial elements had a significantly higher number of grains associated with them than with any other structure, axonal elements had a significantly greater number of grains than dendritic structures. Release of the preloaded [3H]taurine from superfused slices of substantia nigra occurred in response to veratridine, was calcium-dependent and was sensitive to inhibition by high magnesium concentrations or tetrodotoxin. Following the destruction of neurons in the striatum by ibotenic acid injections, although the weight of the ipsilateral substantia nigra was reduced, the uptake of [3H]taurine was not altered. In contrast to this, the veratridine-stimulated release was markedly attenuated, implying that the destruction of striatal neurons causes the loss of sites in the substantia nigra from which exogenous taurine is released. These results add further support to previous suggestions that taurine might act as a neurotransmitter or neuromodulator in the striatonigral pathway.