Effects of whole-body vibration on reproductive physiology in a rat model of whole-body vibration

Findings from epidemiological studies suggest that occupational exposure to whole-body vibration (WBV) may increase the risk of miscarriage and contribute to a reduction in fertility rates in both men and women. However, workers exposed to WBV may also be exposed to other risk factors that contribute to reproductive dysfunction. The goal of this experiment was to examine the effects of WBV on reproductive physiology in a rat model. Male and female rats were exposed to WBV at the resonant frequency of the torso (31.5 Hz, 0.3 g amplitude) for 4 hr/day for 10 days. WBV exposure resulted in a significant reduction in number of developing follicles, and decrease in circulating estradiol concentrations, ovarian luteinizing hormone receptor protein levels, and marked changes in transcript levels for several factors involved in follicular development, cell cycle, and steroidogenesis. In males, WBV resulted in a significant reduction in spermatids and circulating prolactin levels, elevation in number of males having higher circulating testosterone concentrations, and marked alterations in levels of transcripts associated with oxidative stress, inflammation, and factors involved in regulating the cell cycle. Based upon these findings data indicate that occupational exposure to WBV contributes to adverse alterations in reproductive physiology in both genders that may lead to reduction in fertility.

Sub-ppm gas phase Raman spectroscopy in an anti-resonant hollow core fiber

We demonstrate recent progress in the development of a Raman gas sensor using a single cladding ring anti-resonant hollow core micro-structured optical fiber (HC-ARF) and a low power pump source. The HC-ARF was designed specifically for low attenuation and wide bandwidth in the visible spectral region and provided low loss at both the pump wavelength (532 nm) and Stokes wavelengths up to a Raman shift of 5000 cm^-1. A novel selective core pressurization scheme was also implemented to further reduce the confinement loss, improving the Raman signal enhancement by a factor of 1.9 compared to a standard fiber filling scheme. By exploiting longer lengths of fiber, direct detection of both methane and hydrogen at concentrations of 5 and 10 ppm respectively is demonstrated and a noise equivalent limit-of-detection of 0.15 ppm is calculated for methane.

Intracellular Storage Reduces Stoichiometric Imbalances in Soil Microbial Biomass – A Theoretical Exploration

Microbial intracellular storage is key to defining microbial resource use strategies and could contribute to carbon (C) and nutrient cycling. However, little attention has been devoted to the role of intracellular storage in soil processes, in particular from a theoretical perspective. Here we fill this gap by integrating intracellular storage dynamics into a microbially explicit soil C and nutrient cycling model. Two ecologically relevant modes of storage are considered: reserve storage, in which elements are routed to a storage compartment in proportion to their uptake rate, and surplus storage, in which elements in excess of microbial stoichiometric requirements are stored and limiting elements are remobilized from storage to fuel growth and microbial maintenance. Our aim is to explore with this model how these different storage modes affect the retention of C and nutrients in active microbial biomass under idealized conditions mimicking a substrate pulse experiment. As a case study, we describe C and phosphorus (P) dynamics using literature data to estimate model parameters. Both storage modes enhance the retention of elements in microbial biomass, but the surplus storage mode is more effective to selectively store or remobilize C and nutrients according to microbial needs. Enhancement of microbial growth by both storage modes is largest when the substrate C:nutrient ratio is high (causing nutrient limitation after substrate addition) and the amount of added substrate is large. Moreover, storage increases biomass nutrient retention and growth more effectively when resources are supplied in a few large pulses compared to several smaller pulses (mimicking a nearly constant supply), which suggests storage to be particularly relevant in highly dynamic soil microhabitats. Overall, our results indicate that storage dynamics are most important under conditions of strong stoichiometric imbalance and may be of high ecological relevance in soil environments experiencing large variations in C and nutrient supply.

Multiplex digital spatial profiling of proteins and RNA in fixed tissue

Digital Spatial Profiling (DSP) is a method for highly multiplex spatial profiling of proteins or RNAs suitable for use on formalin-fixed, paraffin-embedded (FFPE) samples. The approach relies on (1) multiplexed readout of proteins or RNAs using oligonucleotide tags; (2) oligonucleotide tags attached to affinity reagents (antibodies or RNA probes) through a photocleavable (PC) linker; and (3) photocleaving light projected onto the tissue sample to release PC oligonucleotides in any spatial pattern across a region of interest (ROI) covering 1 to ~5,000 cells. DSP is capable of single-cell sensitivity within an ROI using the antibody readout, with RNA detection feasible down to ~600 individual mRNA transcripts. We show spatial profiling of up to 44 proteins and 96 genes (928 RNA probes) in lymphoid, colorectal tumor and autoimmune tissues by using the nCounter system and 1,412 genes (4,998 RNA probes) by using next-generation sequencing (NGS). DSP may be used to profile not only proteins and RNAs in biobanked samples but also immune markers in patient samples, with potential prognostic and predictive potential for clinical decision-making.

Evaluation of a novel extended automated particle-based multi-analyte assay for the detection of autoantibodies in the diagnosis of primary biliary cholangitis

Background

Anti-mitochondrial autoantibodies (AMA) detected by indirect immunofluorescence (IIF) on rodent tissues are the diagnostic marker of primary biliary cholangitis (PBC). However, up to 15% of patients with PBC are AMA-negative by IIF. In the effort to close the serological gap and improve the diagnostic sensitivity of PBC testing, recently, novel autoantibodies specific for PBC, such as kelch-like 12 (KLHL12, KLp epitope) and hexokinase 1 (HK1) have been described. In this study, we evaluated the autoantibody profile in a large cohort of PBC patients and in patients with other liver disease, including anti-HK1 and anti-KLp autoantibodies.

Methods

Sera of 194 PBC patients (126 AMA-IIF-positive and 68 AMA-IIF-negative) and 138 disease controls were tested for a panel of PBC-specific antibodies (MIT3, sp100, gp210, HK1, KLp) using a new automated particle-based multi-analyte technology (PMAT) assay on the Aptiva instrument (Inova).

Results

Selecting a cutoff yielding a specificity of >95% for all the markers, the sensitivity for anti-MIT3, anti-sp100, anti-gp210, anti-HK1 and anti-KLp in the PBC AMA-IIF-negative cohort was 20.6%, 16.2%, 23.5%, 22.0%, 17.6 and 13.2%, respectively. Six out of the 68 (8.8%) AMA-IIF negative sera were positive for anti-HK1 or anti-KLp alone. Using these new markers in addition to anti-MIT3, anti-sp100 and anti-gp210, the overall sensitivity in this cohort of AMA-IIF-negative patients increased from 53% to 61.8%, reducing the serological gap in AMA-negative PBC patients.

Conclusions

PBC antibody profiling, made possible by the new Aptiva-PMAT technology, allows recognition of a higher number of AMA-negative PBC patients than conventional immunoassays and may represent a useful tool to evaluate the prognostic significance of autoantibody association in PBC patients.

Qualitative evaluation of paediatric surgical otolaryngology content on YouTube

OBJECTIVE

This study evaluated the quality of YouTube content focusing on common paediatric otolaryngology procedures, as this content can influence the opinions and medical decisions of patients.

METHODS

A total of 120 YouTube videos were compiled to review using the terms 'adenoid removal', 'adenoidectomy', 'ear tubes', 'tympanostomy', 'tonsil removal' and 'tonsillectomy'. The Discern criteria was used to rate the quality of health information presented in each video.

RESULTS

The mean bias Discern score was 3.18 and the mean overall Discern score was 2.39. Videos including US board certified physicians were rated significantly higher (p < 0.001) than videos without (bias Discern score = 3.00 vs 2.38; overall Discern score = 3.79 vs 1.55). The videos had been viewed a total of 176 769 549 times.

CONCLUSION

Unbiased, high quality videos on YouTube are lacking. As patients may rely on this information when making medical decisions, it is important that practitioners continually evaluate and improve this video content. Otolaryngologists should be prepared to discuss YouTube content with patients.

Mitochondrial respiratory chain function and content are preserved in the skeletal muscle of active very old men and women

Introduction

The loss of mitochondrial function and content have been implicated in sarcopenia although they have been little studied in the very old, the group in which sarcopenia is most common. In this pilot study, our aim was to determine if mitochondrial respiratory chain function and content are preserved among healthy 85-year-olds.

Methods

We recruited 19 participants (11 female) through their general practitioner and assessed their medical history, functional status and self-reported physical activity. We identified sarcopenia using grip strength, Timed Up-and-Go and bioimpedance analysis. We assessed mitochondrial respiratory chain function using phosphorous magnetic resonance spectroscopy, estimating τ_1/2 PCr, the recovery half-time of phosphocreatine in the calf muscles following a bout of aerobic exercise. We performed a biopsy of the vastus lateralis muscle and assessed mitochondrial respiratory chain content by measuring levels of subunits of complex I and IV of the respiratory chain, expressed as Z-scores relative to that in young controls.

Results

Participants had a median (IQR) of 2 (1,3) long-term conditions, reported regular aerobic physical activity, and one participant (5.3%) had sarcopenia. Sixteen participants completed the magnetic resonance protocol and the mean (SD) τ_1/2 PCr of 35.6 (11.3) seconds was in keeping with preserved mitochondrial function. Seven participants underwent muscle biopsy and the mean fibre Z-scores were −0.7 (0.7) and −0.2 (0.4) for complexes I and IV, respectively, suggesting preserved content of mitochondrial respiratory chain enzymes.

Conclusion

Muscle mitochondrial respiratory chain function and content are preserved in a sample of active, well-functioning 85-year-olds, among whom sarcopenia was uncommon. The results from this study will help inform future work examining the association between muscle mitochondrial deficiency and sarcopenia.

The effects of feed force on rivet bucking bar vibrations

Percussive riveting is the primary process for attaching the outer sheet metal "skins" of an aircraft to its airframe. Workers using manually-operated riveting tools (riveting hammers and rivet bucking bars) are exposed to significant levels of hand-transmitted vibration (HTV) and are at risk of developing components of hand-arm vibration syndrome (HAVS). To protect workers, employers can assess and select riveting tools that produce reduced HTV exposures. Researchers at the National Institute for Occupational Safety & Health (NIOSH) have developed a laboratory-based apparatus and methodology to evaluate the vibrations of rivet bucking bars. Using this simulated riveting approach, this study investigated the effects of feed force on the vibrations of several typical rivet bucking bars and that transmitted to the bucking bar operator's wrist. Five bucking bar models were assessed under three levels of feed force. The study results demonstrate that the feed force can be a major influencing factor on bucking bar vibrations. Similar feed force effects were observed at the bucking bar operator's wrist. This study also shows that different bucking bar designs will respond differently to variations in feed force. Some bucking bar designs may offer reduced vibration exposures to the bar operator's fingers while providing little attenuation of wrist acceleration. Knowledge of how rivet bucking bar models respond to riveting hammer vibrations can be important for making informed bucking bar selections. The study results indicate that, to help in the appropriate selection of bucking bars, candidate bar models should be evaluated at multiple feed force levels. The results also indicate that the bucking bar model, feed force level, or the bucking bar operator have no meaningful effects on the vibration excitation (riveting hammer), which further suggests that the test apparatus proposed by NIOSH researchers meets the basic requirements for a stable vibration source in laboratory-based bucking bar vibration assessments. This study provides relevant information that can be used to help develop a standardized laboratory-based bucking bar evaluation methodology and to help in the selection of appropriate bucking bars for various workplace riveting applications.

RELEVANCE TO INDUSTRY

Because the feed force level can affect HTV exposures to bucking bar operators, the feed force required for specific riveting operations should be an important consideration when selecting bucking bar models. This study provides useful information about bucking bar responses to riveting hammer vibrations; this knowledge can improve bucking bar selections.

Population-based cohort study of variation in the use of emergency cholecystectomy for benign gallbladder diseases

Background

The aims of this prospective population-based cohort study were to identify the patient and hospital characteristics associated with emergency cholecystectomy, and the influences of these in determining variations between hospitals.

Methods

Data were collected for consecutive patients undergoing cholecystectomy in acute UK and Irish hospitals between 1 March and 1 May 2014. Potential explanatory variables influencing the performance of emergency cholecystectomy were analysed by means of multilevel, multivariable logistic regression modelling using a two-level hierarchical structure with patients (level 1) nested within hospitals (level 2).

Results

Data were collected on 4744 cholecystectomies from 165 hospitals. Increasing age, lower ASA fitness grade, biliary colic, the need for further imaging (magnetic retrograde cholangiopancreatography), endoscopic interventions (endoscopic retrograde cholangiopancreatography) and admission to a non-biliary centre significantly reduced the likelihood of an emergency cholecystectomy being performed. The multilevel model was used to calculate the probability of receiving an emergency cholecystectomy for a woman aged 40 years or over with an ASA grade of I or II and a BMI of at least 25·0 kg/m2, who presented with acute cholecystitis with an ultrasound scan showing a thick-walled gallbladder and a normal common bile duct. The mean predicted probability of receiving an emergency cholecystectomy was 0·52 (95 per cent c.i. 0·45 to 0·57). The predicted probabilities ranged from 0·02 to 0·95 across the 165 hospitals, demonstrating significant variation between hospitals.

Conclusion

Patients with similar characteristics presenting to different hospitals with acute gallbladder pathology do not receive comparable care.

Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s^{-2}/sqrt[Hz], or (0.54±0.01)×10^{-15}  g/sqrt[Hz], with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/sqrt[Hz], about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s^{-2}/sqrt[Hz] down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

Antivibration gloves: effects on vascular and sensorineural function, an animal model

Anti-vibration gloves have been used to block the transmission of vibration from powered hand tools to the user, and to protect users from the negative health consequences associated with exposure to vibration. However, there are conflicting reports as to the efficacy of gloves in protecting workers. The goal of this study was to use a characterized animal model of vibration-induced peripheral vascular and nerve injury to determine whether antivibration materials reduced or inhibited the effects of vibration on these physiological symptoms. Rats were exposed to 4 h of tail vibration at 125 Hz with an acceleration 49 m/s(2). The platform was either bare or covered with antivibrating glove material. Rats were tested for tactile sensitivity to applied pressure before and after vibration exposure. One day following the exposure, ventral tail arteries were assessed for sensitivity to vasodilating and vasoconstricting factors and nerves were examined histologically for early indicators of edema and inflammation. Ventral tail artery responses to an α2C-adrenoreceptor agonist were enhanced in arteries from vibration-exposed rats compared to controls, regardless of whether antivibration materials were used or not. Rats exposed to vibration were also less sensitive to pressure after exposure. These findings are consistent with experimental findings in humans suggesting that antivibration gloves may not provide protection against the adverse health consequences of vibration exposure in all conditions. Additional studies need to be done examining newer antivibration materials.

Splenic laceration with a twist: a lesson learnt from gastric volvulus

Acute gastric volvulus is an uncommon entity that requires prompt diagnosis and management to prevent potential life threatening complications. We present a rare case of splenic laceration secondary to acute gastric volvulus.

Integrating quality postnatal care into PMTCT in Swaziland

Swaziland's prevention of mother-to-child transmission (PMTCT) programme is linked to maternal and newborn health (MNH) services, but is mainly focussed on HIV/AIDS. Existing MNH services are inadequate, especially postnatal care (PNC) of mothers and babies, with delayed postnatal visits occurring at 4-6 weeks after delivery. Fifty-seven percent of staff in seven Swazi health facilities were trained in promoting and providing early PNC. A final evaluation showed a 20-fold increase in the number of visits coming for an early postnatal visit (within the first three days after birth). A direct observation of the client-provider interaction showed a significant increase in the competence of the health workers related to postnatal examinations, and care of mothers and babies (p<0.05- < 0.01). The percentage of women breastfeeding within one hour of delivery increased by 41% in HIV-positive mothers and 52% in HIV-negative mothers. Cotrimoxazole prophylaxis for HIV-exposed infants increased by 24%. Although, health workers were observed providing counselling, maternal recall of messages was deficient, suggesting the need for additional strategies for promoting healthy behaviours. High-quality integrated PMTCT programmes and MNH postnatal services are feasible and acceptable, and can result in promoting early postnatal visits and improved care of both HIV-positive and HIV-negative mothers and their babies.

An evaluation of impact wrench vibration emissions and test methods

In the interest of providing more effective evaluations of impact wrench vibration exposures and the development of improved methods for measuring vibration emissions produced by these tools, this study focused on three variables: acceleration measured at the tool surface, vibration exposure duration per test trial, and the amount of torque required to unseat the nuts following a test trial. For this evaluation, six experienced male impact wrench operators used three samples each of five impact wrench models (four pneumatic models and one battery-powered model) in a simulated work task. The test setup and procedures were based on those provided by an International Organization for Standardization (ISO) Technical Committee overseeing the revision of ISO 8662-7. The work task involved the seating of 10 nuts onto 10 bolts mounted on steel plates. The results indicate that acceleration magnitudes vary not only by tool type but also by individual tools within a type. Thus, evaluators are cautioned against drawing conclusions based on small numbers of tools and/or tool operators. Appropriate sample sizes are suggested. It was further noted that evaluators could draw different conclusions if tool assessments are based on ISO-weighted acceleration as opposed to unweighted acceleration. As expected, vibration exposure durations varied by tool type and by test subject; duration means varied more for study participants than they did for tool types. For the 12 pneumatic tools evaluated in this study, torque varied directly with tool handle acceleration. Therefore, in order to reduce vibration exposure, tools should be selected and adjusted so that they produce no more than the needed torque for the task at hand.

Corrigendum to: Estimating the internal conductance to CO2 movement

The concentration of CO₂ in the chloroplast is less than atmospheric owing to a series of gas-phase and liquid-phase resistances. For a long time it was assumed that the concentration of CO₂ in the chloroplasts is the same as in the intercellular spaces (e.g. as measured by gas exchange). There is mounting evidence that this assumption is invalid and that CO₂ concentrations in the chloroplasts are significantly less than intercellular CO₂. It is now generally accepted that internal conductance (g_i) is a significant limitation to photosynthesis, often as large as that due to stomata. Internal conductance describes this decrease in CO₂ concentration between the intercellular spaces and chloroplasts as a function of net photosynthesis [g_i = A/(C_i - C_c)]. Internal conductance is commonly estimated by simultaneous measurements of gas exchange and chlorophyll a fluorescence or instantaneous discrimination against ¹³CO₂. These common methods are complemented by three alternative methods based on (a) the difference between intercellular and chloroplastic CO₂ photocompensation points, (b) the curvature of an A/C_i curve, and (c) the initial slope of an A/C_i curve v. the estimated initial slope of an A/C_c curve. The theoretical basis and protocols for estimating internal conductance are described. The common methods have poor precision with relative standard deviations commonly > 10%; much less is known of the precision of the three alternative methods. Accuracy of the methods is largely unknown because all methods share some common assumptions and no truly independent and assumption-free method exists. Some assumptions can and should be tested (e.g. the relationship of fluorescence with electron transport). Methods generally require knowledge of either the kinetic parameters of Rubisco, or isotopic fractionation by Rubisco. These parameters are difficult to measure, and thus are generally assumed a priori. For parameters such as these a sensitivity analysis is recommended. One means of improving confidence in g_i estimates is by using two or more methods, but it is essential that the methods chosen share as few common assumptions as possible. All methods require accurate and precise measurements of A and C_i - these are best achieved by minimising leaks, maximising the signal-to-noise ratio by using a large leaf area and moderate flow rate, and by taking into account cuticular and boundary layer conductances.

Estimating the internal conductance to CO2 movement

The concentration of CO₂ in the chloroplast is less than atmospheric owing to a series of gas-phase and liquid-phase resistances. For a long time it was assumed that the concentration of CO₂ in the chloroplasts is the same as in the intercellular spaces (e.g. as measured by gas exchange). There is mounting evidence that this assumption is invalid and that CO₂ concentrations in the chloroplasts are significantly less than intercellular CO₂. It is now generally accepted that internal conductance (g_i) is a significant limitation to photosynthesis, often as large as that due to stomata. Internal conductance describes this decrease in CO₂ concentration between the intercellular spaces and chloroplasts as a function of net photosynthesis [g_i = A / (C_i - C_c)]. Internal conductance is commonly estimated by simultaneous measurements of gas exchange and chlorophyll a fluorescence or instantaneous discrimination against ¹³CO₂. These common methods are complemented by three alternative methods based on (a) the difference between intercellular and chloroplastic CO₂ photocompensation points, (b) the curvature of an A / C_i curve, and (c) the initial slope of an A / C_i curve v. the estimated initial slope of an A / C_c curve. The theoretical basis and protocols for estimating internal conductance are described. The common methods have poor precision with relative standard deviations commonly > 10%; much less is known of the precision of the three alternative methods. Accuracy of the methods is largely unknown because all methods share some common assumptions and no truly independent and assumption-free method exists. Some assumptions can and should be tested (e.g. the relationship of fluorescence with electron transport). Methods generally require knowledge of either the kinetic parameters of Rubisco, or isotopic fractionation by Rubisco. These parameters are difficult to measure, and thus are generally assumed a priori. For parameters such as these a sensitivity analysis is recommended. One means of improving confidence in g_i estimates is by using two or more methods, but it is essential that the methods chosen share as few common assumptions as possible. All methods require accurate and precise measurements of A and C_i - these are best achieved by minimising leaks, maximising the signal-to-noise ratio by using a large leaf area and moderate flow rate, and by taking into account cuticular and boundary layer conductances.

POSaM: a fast, flexible, open-source, inkjet oligonucleotide synthesizer and microarrayer

DNA arrays are valuable tools in molecular biology laboratories. Their rapid acceptance was aided by the release of plans for a pin-spotting microarrayer by researchers at Stanford. Inkjet microarraying is a flexible, complementary technique that allows the synthesis of arrays of any oligonucleotide sequences de novo. We describe here an open-source inkjet arrayer capable of rapidly producing sets of unique 9,800-feature arrays.

Vibration energy absorption (VEA) in human fingers-hand-arm system

A methodology for measuring the vibration energy absorbed into the fingers and the palm exposed to vibration is proposed to study the distribution of the vibration energy absorption (VEA) in the fingers-hand-arm system and to explore its potential association with vibration-induced white finger (VWF). The study involved 12 adult male subjects, constant-velocity sinusoidal excitations at 10 different discrete frequencies in the range of 16-1000 Hz, and four different hand-handle coupling conditions (finger pull-only, hand grip-only, palm push-only, and combined grip and push). The results of the study suggest that the VEA into the fingers is considerably less than that into the palm at low frequencies (< or = 25 Hz). They are, however, comparable under the excitations in the 250-1000 Hz frequency range. The finger VEA at high frequencies (> or = 100 Hz) is practically independent of the hand-handle coupling condition. The coupling conditions affect the VEA into the fingers and the palm very differently. The finger VEA results suggest that the ISO standardized frequency weighting (ISO 5349-1, 2001) may underestimate the effect of high frequency vibration on vibration-induced finger disorders. The proposed method may provide new opportunities to examine VEA and its association with VWF and other types of vibration-induced disorders in the hand-arm system.