A branching model of lineage differentiation underpinning the neurogenic potential of enteric glia

Glial cells have been proposed as a source of neural progenitors, but the mechanisms underpinning the neurogenic potential of adult glia are not known. Using single cell transcriptomic profiling, we show that enteric glial cells represent a cell state attained by autonomic neural crest cells as they transition along a linear differentiation trajectory that allows them to retain neurogenic potential while acquiring mature glial functions. Key neurogenic loci in early enteric nervous system progenitors remain in open chromatin configuration in mature enteric glia, thus facilitating neuronal differentiation under appropriate conditions. Molecular profiling and gene targeting of enteric glial cells in a cell culture model of enteric neurogenesis and a gut injury model demonstrate that neuronal differentiation of glia is driven by transcriptional programs employed in vivo by early progenitors. Our work provides mechanistic insight into the regulatory landscape underpinning the development of intestinal neural circuits and generates a platform for advancing glial cells as therapeutic agents for the treatment of neural deficits.

Final Measurement of the ^{235}U Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR

This Letter reports one of the most precise measurements to date of the antineutrino spectrum from a purely ^{235}U-fueled reactor, made with the final dataset from the PROSPECT-I detector at the High Flux Isotope Reactor. By extracting information from previously unused detector segments, this analysis effectively doubles the statistics of the previous PROSPECT measurement. The reconstructed energy spectrum is unfolded into antineutrino energy and compared with both the Huber-Mueller model and a spectrum from a commercial reactor burning multiple fuel isotopes. A local excess over the model is observed in the 5-7 MeV energy region. Comparison of the PROSPECT results with those from commercial reactors provides new constraints on the origin of this excess, disfavoring at 2.0 and 3.7 standard deviations the hypotheses that antineutrinos from ^{235}U are solely responsible and noncontributors to the excess observed at commercial reactors, respectively.

hPSCs-derived Schwann cells serve for disease modeling and drug discovery

In this issue, Majd et al.¹ derive Schwann cells from human pluripotent stem cells (hPSCs), which can be used to study Schwann cell development and physiology and model diabetic neuropathy. hPSC-derived Schwann cells possess the molecular features of primary Schwann cells and are capable of myelination in vitro and in vivo.

Schwann cell precursors represent a neural crest-like state with biased multipotency

Schwann cell precursors (SCPs) are nerve-associated progenitors that can generate myelinating and non-myelinating Schwann cells but also are multipotent like the neural crest cells from which they originate. SCPs are omnipresent along outgrowing peripheral nerves throughout the body of vertebrate embryos. By using single-cell transcriptomics to generate a gene expression atlas of the entire neural crest lineage, we show that early SCPs and late migratory crest cells have similar transcriptional profiles characterised by a multipotent "hub" state containing cells biased towards traditional neural crest fates. SCPs keep diverging from the neural crest after being primed towards terminal Schwann cells and other fates, with different subtypes residing in distinct anatomical locations. Functional experiments using CRISPR-Cas9 loss-of-function further show that knockout of the common "hub" gene Sox8 causes defects in neural crest-derived cells along peripheral nerves by facilitating differentiation of SCPs towards sympathoadrenal fates. Finally, specific tumour populations found in melanoma, neurofibroma and neuroblastoma map to different stages of SCP/Schwann cell development. Overall, SCPs resemble migrating neural crest cells that maintain multipotency and become transcriptionally primed towards distinct lineages.

Mortality-Air Pollution Associations in Low Exposure Environments (MAPLE): Phase 2

INTRODUCTION

Mortality is associated with long-term exposure to fine particulate matter (particulate matter ≤2.5 μm in aerodynamic diameter; PM2.5), although the magnitude and form of these associations remain poorly understood at lower concentrations. Knowledge gaps include the shape of concentration-response curves and the lowest levels of exposure at which increased risks are evident and the occurrence and extent of associations with specific causes of death. Here, we applied improved estimates of exposure to ambient PM2.5 to national population-based cohorts in Canada, including a stacked cohort of 7.1 million people who responded to census year 1991, 1996, or 2001. The characterization of the shape of the concentration-response relationship for nonaccidental mortality and several specific causes of death at low levels of exposure was the focus of the Mortality-Air Pollution Associations in Low Exposure Environments (MAPLE) Phase 1 report. In the Phase 1 report we reported that associations between outdoor PM2.5 concentrations and nonaccidental mortality were attenuated with the addition of ozone (O3) or a measure of gaseous pollutant oxidant capacity (Ox), which was estimated from O3 and nitrogen dioxide (NO2) concentrations. This was motivated by our interests in understanding both the effects air pollutant mixtures may have on mortality and also the role of O3 as a copollutant that shares common sources and precursor emissions with those of PM2.5. In this Phase 2 report, we further explore the sensitivity of these associations with O3 and Ox, evaluate sensitivity to other factors, such as regional variation, and present ambient PM2.5 concentration-response relationships for specific causes of death.

METHODS

PM2.5 concentrations were estimated at 1 km2 spatial resolution across North America using remote sensing of aerosol optical depth (AOD) combined with chemical transport model (GEOS-Chem) simulations of the AOD:surface PM2.5 mass concentration relationship, land use information, and ground monitoring. These estimates were informed and further refined with collocated measurements of PM2.5 and AOD, including targeted measurements in areas of low PM2.5 concentrations collected at five locations across Canada. Ground measurements of PM2.5 and total suspended particulate matter (TSP) mass concentrations from 1981 to 1999 were used to backcast remote-sensing-based estimates over that same time period, resulting in modeled annual surfaces from 1981 to 2016.

Annual exposures to PM2.5 were then estimated for subjects in several national population-based Canadian cohorts using residential histories derived from annual postal code entries in income tax files. These cohorts included three census-based cohorts: the 1991 Canadian Census Health and Environment Cohort (CanCHEC; 2.5 million respondents), the 1996 CanCHEC (3 million respondents), the 2001 CanCHEC (3 million respondents), and a Stacked CanCHEC where duplicate records of respondents were excluded (Stacked CanCHEC; 7.1 million respondents). The Canadian Community Health Survey (CCHS) mortality cohort (mCCHS), derived from several pooled cycles of the CCHS (540,900 respondents), included additional individual information about health behaviors. Follow-up periods were completed to the end of 2016 for all cohorts. Cox proportional hazard ratios (HRs) were estimated for nonaccidental and other major causes of death using a 10-year moving average exposure and 1-year lag. All models were stratified by age, sex, immigrant status, and where appropriate, census year or survey cycle. Models were further adjusted for income adequacy quintile, visible minority status, Indigenous identity, educational attainment, labor-force status, marital status, occupation, and ecological covariates of community size, airshed, urban form, and four dimensions of the Canadian Marginalization Index (Can-Marg; instability, deprivation, dependency, and ethnic concentration). The mCCHS analyses were also adjusted for individual-level measures of smoking, alcohol consumption, fruit and vegetable consumption, body mass index (BMI), and exercise behavior.

In addition to linear models, the shape of the concentration-response function was investigated using restricted cubic splines (RCS). The number of knots were selected by minimizing the Bayesian Information Criterion (BIC). Two additional models were used to examine the association between nonaccidental mortality and PM2.5. The first is the standard threshold model defined by a transformation of concentration equaling zero if the concentration was less than a specific threshold value and concentration minus the threshold value for concentrations above the threshold. The second additional model was an extension of the Shape Constrained Health Impact Function (SCHIF), the eSCHIF, which converts RCS predictions into functions potentially more suitable for use in health impact assessments. Given the RCS parameter estimates and their covariance matrix, 1,000 realizations of the RCS were simulated at concentrations from the minimum to the maximum concentration, by increments of 0.1 μg/m3. An eSCHIF was then fit to each of these RCS realizations. Thus, 1,000 eSCHIF predictions and uncertainty intervals were determined at each concentration within the total range.

Sensitivity analyses were conducted to examine associations between PM2.5 and mortality when in the presence of, or stratified by tertile of, O3 or Ox. Additionally, associations between PM2.5 and mortality were assessed for sensitivity to lower concentration thresholds, where person-years below a threshold value were assigned the mean exposure within that group. We also examined the sensitivity of the shape of the nonaccidental mortality-PM2.5 association to removal of person-years at or above 12 μg/m3 (the current U.S. National Ambient Air Quality Standard) and 10 μg/m3 (the current Canadian and former [2005] World Health Organization [WHO] guideline, and current WHO Interim Target-4). Finally, differences in the shapes of PM2.5-mortality associations were assessed across broad geographic regions (airsheds) within Canada.

RESULTS

The refined PM2.5 exposure estimates demonstrated improved performance relative to estimates applied previously and in the MAPLE Phase 1 report, with slightly reduced errors, including at lower ranges of concentrations (e.g., for PM2.5 <10 μg/m3).

Positive associations between outdoor PM2.5 concentrations and nonaccidental mortality were consistently observed in all cohorts. In the Stacked CanCHEC analyses (1.3 million deaths), each 10-μg/m3 increase in outdoor PM2.5 concentration corresponded to an HR of 1.084 (95% confidence interval [CI]: 1.073 to 1.096) for nonaccidental mortality. For an interquartile range (IQR) increase in PM2.5 mass concentration of 4.16 μg/m3 and for a mean annual nonaccidental death rate of 92.8 per 10,000 persons (over the 1991-2016 period for cohort participants ages 25-90), this HR corresponds to an additional 31.62 deaths per 100,000 people, which is equivalent to an additional 7,848 deaths per year in Canada, based on the 2016 population. In RCS models, mean HR predictions increased from the minimum concentration of 2.5 μg/m3 to 4.5 μg/m3, flattened from 4.5 μg/m3 to 8.0 μg/m3, then increased for concentrations above 8.0 μg/m3. The threshold model results reflected this pattern with -2 log-likelihood values being equal at 2.5 μg/m3 and 8.0 μg/m3. However, mean threshold model predictions monotonically increased over the concentration range with the lower 95% CI equal to one from 2.5 μg/m3 to 8.0 μg/m3. The RCS model was a superior predictor compared with any of the threshold models, including the linear model.

In the mCCHS cohort analyses inclusion of behavioral covariates did not substantially change the results for both linear and nonlinear models. We examined the sensitivity of the shape of the nonaccidental mortality-PM2.5 association to removal of person-years at or above the current U.S. and Canadian standards of 12 μg/m3 and 10 μg/m3, respectively. In the full cohort and in both restricted cohorts, a steep increase was observed from the minimum concentration of 2.5 μg/m3 to 5 μg/m3. For the full cohort and the <12 μg/m3 cohort the relationship flattened over the 5 to 9 μg/m3 range and then increased above 9 μg/m3. A similar increase was observed for the <10 μg/m3 cohort followed by a clear decline in the magnitude of predictions over the 5 to 9 μg/m3 range and an increase above 9 μg/m3. Together these results suggest that a positive association exists for concentrations >9 μg/m3 with indications of adverse effects on mortality at concentrations as low as 2.5 μg/m3.

Among the other causes of death examined, PM2.5 exposures were consistently associated with an increased hazard of mortality due to ischemic heart disease, respiratory disease, cardiovascular disease, and diabetes across all cohorts. Associations were observed in the Stacked CanCHEC but not in all other cohorts for cerebrovascular disease, pneumonia, and chronic obstructive pulmonary disease (COPD) mortality. No significant associations were observed between mortality and exposure to PM2.5 for heart failure, lung cancer, and kidney failure.

In sensitivity analyses, the addition of O3 and Ox attenuated associations between PM2.5 and mortality. When analyses were stratified by tertiles of copollutants, associations between PM2.5 and mortality were only observed in the highest tertile of O3 or Ox. Across broad regions of Canada, linear HR estimates and the shape of the eSCHIF varied substantially, possibly reflecting underlying differences in air pollutant mixtures not characterized by PM2.5 mass concentrations or the included gaseous pollutants. Sensitivity analyses to assess regional variation in population characteristics and access to healthcare indicated that the observed regional differences in concentration-mortality relationships, specifically the flattening of the concentration-mortality relationship over the 5 to 9 μg/m3 range, was not likely related to variation in the makeup of the cohort or its access to healthcare, lending support to the potential role of spatially varying air pollutant mixtures not sufficiently characterized by PM2.5 mass concentrations.

CONCLUSIONS

In several large, national Canadian cohorts, including a cohort of 7.1 million unique census respondents, associations were observed between exposure to PM2.5 with nonaccidental mortality and several specific causes of death. Associations with nonaccidental mortality were observed using the eSCHIF methodology at concentrations as low as 2.5 μg/m3, and there was no clear evidence in the observed data of a lower threshold, below which PM2.5 was not associated with nonaccidental mortality.

Joint Determination of Reactor Antineutrino Spectra from ^{235}U and ^{239}Pu Fission by Daya Bay and PROSPECT

A joint determination of the reactor antineutrino spectra resulting from the fission of ^{235}U and ^{239}Pu has been carried out by the Daya Bay and PROSPECT Collaborations. This Letter reports the level of consistency of ^{235}U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant ^{235}U and ^{239}Pu isotopes and improves the uncertainty of the ^{235}U spectral shape to about 3%. The ^{235}U and ^{239}Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the ^{235}U and ^{239}Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.

Joint Measurement of the ^{235}U Antineutrino Spectrum by PROSPECT and STEREO

The PROSPECT and STEREO collaborations present a combined measurement of the pure ^{235}U antineutrino spectrum, without site specific corrections or detector-dependent effects. The spectral measurements of the two highest precision experiments at research reactors are found to be compatible with χ^{2}/ndf=24.1/21, allowing a joint unfolding of the prompt energy measurements into antineutrino energy. This ν[over ¯]_{e} energy spectrum is provided to the community, and an excess of events relative to the Huber model is found in the 5-6 MeV region. When a Gaussian bump is fitted to the excess, the data-model χ^{2} value is improved, corresponding to a 2.4σ significance.

Prediction of neo-adjuvant chemotherapy response in bladder cancer: the impact of clinical parameters and routine biomarkers

PURPOSE

To investigate the role of clinical parameters and immunohistochemical (IHC) biomarkers in their feasibility to predict the effect of neo-adjuvant chemotherapy (NAC) in patients with muscle-invasive urothelial bladder cancer (MIBC).

MATERIALS AND METHODS

The first 76 consecutive patients with MIBC treated with NAC and radical cystectomy in two University hospitals in Finland between 2008 and 2013 were chosen for this study. After excluding patients with non-urothelial cancer, less than two cycles of chemotherapy, no tissue material for IHC analysis or non-muscle-invasive bladder cancer in re-review, 59 patients were included in the final analysis. A tissue microarray block was constructed from the transurethral resection samples and IHC stainings of Ki-67, p53, Her-2 and EGFR were made. The correlations between histological features in transurethral resection samples and immune-histochemical stainings were calculated. The associations of clinicopathological parameters and IHC stainings with NAC response were evaluated. Factors affecting survival were estimated.

RESULTS

The complete response rate after NAC was 44%. A higher number of chemotherapy cycles was associated with better response to neo-adjuvant chemotherapy. No response to neo-adjuvant chemotherapy and female gender was associated with decreased cancer-specific survival. The IHC stainings used failed to show an association with neo-adjuvant chemotherapy response and overall or cancer specific survival.

CONCLUSIONS

Patients who do not respond to neo-adjuvant chemotherapy do significantly worse than responders. This study could not find clinical tools to distinguish responders from non-responders. Further studies preferably with larger cohorts addressing this issue are warranted to improve the selection of patients for neo-adjuvant chemotherapy.

Single-cell ATAC and RNA sequencing reveal pre-existing and persistent cells associated with prostate cancer relapse

Prostate cancer is heterogeneous and patients would benefit from methods that stratify those who are likely to respond to systemic therapy. Here, we employ single-cell assays for transposase-accessible chromatin (ATAC) and RNA sequencing in models of early treatment response and resistance to enzalutamide. In doing so, we identify pre-existing and treatment-persistent cell subpopulations that possess regenerative potential when subjected to treatment. We find distinct chromatin landscapes associated with enzalutamide treatment and resistance that are linked to alternative transcriptional programs. Transcriptional profiles characteristic of persistent cells are able to stratify the treatment response of patients. Ultimately, we show that defining changes in chromatin and gene expression in single-cell populations from pre-clinical models can reveal as yet unrecognized molecular predictors of treatment response. This suggests that the application of single-cell methods with high analytical resolution in pre-clinical models may powerfully inform clinical decision-making.

Single-cell transcriptomics of human embryos identifies multiple sympathoblast lineages with potential implications for neuroblastoma origin

Characterization of the progression of cellular states during human embryogenesis can provide insights into the origin of pediatric diseases. We examined the transcriptional states of neural crest- and mesoderm-derived lineages differentiating into adrenal glands, kidneys, endothelium and hematopoietic tissue between post-conception weeks 6 and 14 of human development. Our results reveal transitions connecting the intermediate mesoderm and progenitors of organ primordia, the hematopoietic system and endothelial subtypes. Unexpectedly, by using a combination of single-cell transcriptomics and lineage tracing, we found that intra-adrenal sympathoblasts at that stage are directly derived from nerve-associated Schwann cell precursors, similarly to local chromaffin cells, whereas the majority of extra-adrenal sympathoblasts arise from the migratory neural crest. In humans, this process persists during several weeks of development within the large intra-adrenal ganglia-like structures, which may also serve as reservoirs of originating cells in neuroblastoma.

Nonfuel Antineutrino Contributions in the High Flux Isotope Reactor

Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ν ¯ e is important when making theoretical predictions. One source of ν ¯ e that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ν ¯ e rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ν ¯ e sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ν ¯ e source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ν ¯ e contributions from HFIR to PROSPECT amount to 1% above the inverse beta decay threshold with a maximum contribution of 9% in the 1.8-2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ν ¯ e contribution.

Determination of Campesterol, Stigmasterol, and Beta-Sitosterol in Saw Palmetto Raw Materials and Dietary Supplements by Gas Chromatography: Collaborative Study

An interlaboratory study was conducted to evaluate a method for the determination of campesterol, stigmasterol, and beta-sitosterol in saw palmetto raw materials and dietary supplements at levels &gt;1.00 mg/100 g based on a 23 g sample. Test samples were saponified at high temperature with ethanolic KOH solution. The unsaponifiable fraction containing phytosterols (campesterol, stigmasterol, and beta-sitosterol) was extracted with toluene. Phytosterols were derivatized to trimethylsilyl ethers and then quantified by gas chromatography with hydrogen flame ionization detection. Twelve blind duplicates, one of which was fortified, were successfully analyzed by 10 collaborators. Recoveries were obtained for the sample that was fortified. The results were 99.8, 111, and 111% for campesterol, stigmasterol, and beta-sitosterol, respectively. For repeatability, the relative standard deviation (RSDr) ranged from 3.93 to 17.3% for campesterol, 3.56 to 22.7% for stigmasterol, and 3.70 to 43.9% for beta-sitosterol. For reproducibility, the RSDR ranged from 7.97 to 22.6%, 0 to 26.7%, and 5.27 to 43.9% for campesterol, stigmasterol, and beta-sitosterol, respectively. Overall, the Study Director approved 5 materials with acceptable HorRat values for campesterol, stigmasterol, and beta-sitosterol ranging from 1.02 to 2.16.

Mechanical stimulation of growth plate chondrocytes: Previous approaches and future directions

Growth plate cartilage resides near the ends of long bones and is the primary driver of skeletal growth. During growth, both intrinsically and extrinsically generated mechanical stresses act on chondrocytes in the growth plate. Although the role of mechanical stresses in promoting tissue growth and homeostasis has been strongly demonstrated in articular cartilage of the major skeletal joints, effects of stresses on growth plate cartilage and bone growth are not as well established. Here, we review the literature on mechanobiology in growth plate cartilage at macroscopic and microscopic scales, with particular emphasis on comparison of results obtained using different methodological approaches, as well as from whole animal and in vitro experiments. To answer these questions, macroscopic mechanical stimulators have been developed and applied to study mechanobiology of growth plate cartilage and chondrocytes. However, the previous approaches have tested a limited number of stress conditions, and the mechanobiology of a single chondrocyte has not been well studied due to limitations of the macroscopic mechanical stimulators. We explore how microfluidics devices can overcome these limitations and improve current understanding of growth plate chondrocyte mechanobiology. In particular, microfluidic devices can generate multiple stress conditions in a single platform and enable real-time monitoring of metabolism and cellular behavior using optical microscopy. Systematic characterization of the chondrocytes using microfluidics will enhance our understanding of how to use mechanical stresses to control the bone growth and the properties of tissue-engineered growth plate cartilage.

Mortality-Air Pollution Associations in Low-Exposure Environments (MAPLE): Phase 1

INTRODUCTION

Fine particulate matter (particulate matter ≤2.5 μm in aerodynamic diameter, or PM2.5) is associated with mortality, but the lower range of relevant concentrations is unknown. Novel satellite-derived estimates of outdoor PM2.5 concentrations were applied to several large population-based cohorts, and the shape of the relationship with nonaccidental mortality was characterized, with emphasis on the low concentrations (<12 μg/m3) observed throughout Canada.

METHODS

Annual satellite-derived estimates of outdoor PM2.5 concentrations were developed at 1-km2 spatial resolution across Canada for 2000-2016 and backcasted to 1981 using remote sensing, chemical transport models, and ground monitoring data. Targeted ground-based measurements were conducted to measure the relationship between columnar aerosol optical depth (AOD) and ground-level PM2.5. Both existing and targeted ground-based measurements were analyzed to develop improved exposure data sets for subsequent epidemiological analyses.

Residential histories derived from annual tax records were used to estimate PM2.5 exposures for subjects whose ages ranged from 25 to 90 years. About 8.5 million were from three Canadian Census Health and Environment Cohort (CanCHEC) analytic files and another 540,900 were Canadian Community Health Survey (CCHS) participants. Mortality was linked through the year 2016. Hazard ratios (HR) were estimated with Cox Proportional Hazard models using a 3-year moving average exposure with a 1-year lag, with the year of follow-up as the time axis. All models were stratified by 5-year age groups, sex, and immigrant status. Covariates were based on directed acyclical graphs (DAG), and included contextual variables (airshed, community size, neighborhood dependence, neighborhood deprivation, ethnic concentration, neighborhood instability, and urban form). A second model was examined including the DAG-based covariates as well as all subject-level risk factors (income, education, marital status, indigenous identity, employment status, occupational class, and visible minority status) available in each cohort. Additional subject-level behavioral covariates (fruit and vegetable consumption, leisure exercise frequency, alcohol consumption, smoking, and body mass index [BMI]) were included in the CCHS analysis.

Sensitivity analyses evaluated adjustment for covariates and gaseous copollutants (nitrogen dioxide [NO2] and ozone [O3]), as well as exposure time windows and spatial scales. Estimates were evaluated across strata of age, sex, and immigrant status. The shape of the PM2.5-mortality association was examined by first fitting restricted cubic splines (RCS) with a large number of knots and then fitting the shape-constrained health impact function (SCHIF) to the RCS predictions and their standard errors (SE). This method provides graphical results indicating the RCS predictions, as a nonparametric means of characterizing the concentration-response relationship in detail and the resulting mean SCHIF and accompanying uncertainty as a parametric summary.

Sensitivity analyses were conducted in the CCHS cohort to evaluate the potential influence of unmeasured covariates on air pollution risk estimates. Specifically, survival models with all available risk factors were fit and compared with models that omitted covariates not available in the CanCHEC cohorts. In addition, the PM2.5 risk estimate in the CanCHEC cohort was indirectly adjusted for multiple individual-level risk factors by estimating the association between PM2.5 and these covariates within the CCHS.

RESULTS

Satellite-derived PM2.5 estimates were low and highly correlated with ground monitors. HR estimates (per 10-μg/m3 increase in PM2.5) were similar for the 1991 (1.041, 95% confidence interval [CI]: 1.016-1.066) and 1996 (1.041, 1.024-1.059) CanCHEC cohorts with a larger estimate observed for the 2001 cohort (1.084, 1.060-1.108). The pooled cohort HR estimate was 1.053 (1.041-1.065). In the CCHS an analogous model indicated a HR of 1.13 (95% CI: 1.06-1.21), which was reduced slightly with the addition of behavioral covariates (1.11, 1.04-1.18). In each of the CanCHEC cohorts, the RCS increased rapidly over lower concentrations, slightly declining between the 25th and 75th percentiles and then increasing beyond the 75th percentile. The steepness of the increase in the RCS over lower concentrations diminished as the cohort start date increased. The SCHIFs displayed a supralinear association in each of the three CanCHEC cohorts and in the CCHS cohort.

In sensitivity analyses conducted with the 2001 CanCHEC, longer moving averages (1, 3, and 8 years) and smaller spatial scales (1 km2 vs. 10 km2) of exposure assignment resulted in larger associations between PM2.5 and mortality. In both the CCHS and CanCHEC analyses, the relationship between nonaccidental mortality and PM2.5 was attenuated when O3 or a weighted measure of oxidant gases was included in models. In the CCHS analysis, but not in CanCHEC, PM2.5 HRs were also attenuated by the inclusion of NO2. Application of the indirect adjustment and comparisons within the CCHS analysis suggests that missing data on behavioral risk factors for mortality had little impact on the magnitude of PM2.5-mortality associations. While immigrants displayed improved overall survival compared with those born in Canada, their sensitivity to PM2.5 was similar to or larger than that for nonimmigrants, with differences between immigrants and nonimmigrants decreasing in the more recent cohorts.

CONCLUSIONS

In several large population-based cohorts exposed to low levels of air pollution, consistent associations were observed between PM2.5 and nonaccidental mortality for concentrations as low as 5 μg/m3. This relationship was supralinear with no apparent threshold or sublinear association.

A Microfluidic Platform for Stimulating Chondrocytes with Dynamic Compression

Mechanical stimuli are known to modulate biological functions of cells and tissues. Recent studies have suggested that compressive stress alters growth plate cartilage architecture and results in growth modulation of long bones of children. To determine the role of compressive stress in bone growth, we created a microfluidic device actuated by pneumatic pressure, to dynamically (or statically) compress growth plate chondrocytes embedded in alginate hydrogel cylinders. In this article, we describe detailed methods for fabricating and characterizing this device. The advantages of our protocol are: 1) Five different magnitudes of compressive stress can be generated on five technical replicates in a single platform, 2) It is easy to visualize cell morphology via a conventional light microscope, 3) Cells can be rapidly isolated from the device after compression to facilitate downstream assays, and 4) The platform can be applied to study mechanobiology of any cell type that can grow in hydrogels.

Measurement of the Antineutrino Spectrum from ^{235}U Fission at HFIR with PROSPECT

This Letter reports the first measurement of the ^{235}U ν[over ¯]_{e} energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the 85  MW_{th} highly enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based, segmented detector, PROSPECT has observed 31678±304(stat) ν[over ¯]_{e}-induced inverse beta decays, the largest sample from HEU fission to date, 99% of which are attributed to ^{235}U. Despite broad agreement, comparison of the Huber ^{235}U model to the measured spectrum produces a χ^{2}/ndf=51.4/31, driven primarily by deviations in two localized energy regions. The measured ^{235}U spectrum shape is consistent with a deviation relative to prediction equal in size to that observed at low-enriched uranium power reactors in the ν[over ¯]_{e} energy region of 5-7 MeV.

First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT

This Letter reports the first scientific results from the observation of antineutrinos emitted by fission products of ^{235}U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton ^{6}Li-doped liquid scintillator detector covering a baseline range of 7-9 m from the reactor and operating under less than 1 m water equivalent overburden. Data collected during 33 live days of reactor operation at a nominal power of 85 MW yield a detection of 25 461±283 (stat) inverse beta decays. Observation of reactor antineutrinos can be achieved in PROSPECT at 5σ statistical significance within 2 h of on-surface reactor-on data taking. A reactor model independent analysis of the inverse beta decay prompt energy spectrum as a function of baseline constrains significant portions of the previously allowed sterile neutrino oscillation parameter space at 95% confidence level and disfavors the best fit of the reactor antineutrino anomaly at 2.2σ confidence level.

Pneumatic microfluidic cell compression device for high-throughput study of chondrocyte mechanobiology

Hyaline cartilage is a specialized type of connective tissue that lines many moveable joints (articular cartilage) and contributes to bone growth (growth plate cartilage). Hyaline cartilage is composed of a single cell type, the chondrocyte, which produces a unique hydrated matrix to resist compressive stress. Although compressive stress has profound effects on transcriptional networks and matrix biosynthesis in chondrocytes, mechanistic relationships between strain, signal transduction, cell metabolism, and matrix production remain superficial. Here, we describe development and validation of a polydimethylsiloxane (PDMS)-based pneumatic microfluidic cell compression device which generates multiple compression conditions in a single platform. The device contained an array of PDMS balloons of different sizes which were actuated by pressurized air, and the balloons compressed chondrocytes cells in alginate hydrogel constructs. Our characterization and testing of the device showed that the developed platform could compress chondrocytes with various magnitudes simultaneously with negligible effect on cell viability. Also, the device is compatible with live cell imaging to probe early effects of compressive stress, and it can be rapidly dismantled to facilitate molecular studies of compressive stress on transcriptional networks. Therefore, the proposed device will enhance the productivity of chondrocyte mechanobiology studies, and it can be applied to study mechanobiology of other cell types.

A multiplex reverse transcription PCR and automated electronic microarray assay for detection and differentiation of seven viruses affecting swine

Microarray technology can be useful for pathogen detection as it allows simultaneous interrogation of the presence or absence of a large number of genetic signatures. However, most microarray assays are labour-intensive and time-consuming to perform. This study describes the development and initial evaluation of a multiplex reverse transcription (RT)-PCR and novel accompanying automated electronic microarray assay for simultaneous detection and differentiation of seven important viruses that affect swine (foot-and-mouth disease virus [FMDV], swine vesicular disease virus [SVDV], vesicular exanthema of swine virus [VESV], African swine fever virus [ASFV], classical swine fever virus [CSFV], porcine respiratory and reproductive syndrome virus [PRRSV] and porcine circovirus type 2 [PCV2]). The novel electronic microarray assay utilizes a single, user-friendly instrument that integrates and automates capture probe printing, hybridization, washing and reporting on a disposable electronic microarray cartridge with 400 features. This assay accurately detected and identified a total of 68 isolates of the seven targeted virus species including 23 samples of FMDV, representing all seven serotypes, and 10 CSFV strains, representing all three genotypes. The assay successfully detected viruses in clinical samples from the field, experimentally infected animals (as early as 1 day post-infection (dpi) for FMDV and SVDV, 4 dpi for ASFV, 5 dpi for CSFV), as well as in biological material that were spiked with target viruses. The limit of detection was 10 copies/μl for ASFV, PCV2 and PRRSV, 100 copies/μl for SVDV, CSFV, VESV and 1,000 copies/μl for FMDV. The electronic microarray component had reduced analytical sensitivity for several of the target viruses when compared with the multiplex RT-PCR. The integration of capture probe printing allows custom onsite array printing as needed, while electrophoretically driven hybridization generates results faster than conventional microarrays that rely on passive hybridization. With further refinement, this novel, rapid, highly automated microarray technology has potential applications in multipathogen surveillance of livestock diseases.

Oriented clonal cell dynamics enables accurate growth and shaping of vertebrate cartilage

Cartilaginous structures are at the core of embryo growth and shaping before the bone forms. Here we report a novel principle of vertebrate cartilage growth that is based on introducing transversally-oriented clones into pre-existing cartilage. This mechanism of growth uncouples the lateral expansion of curved cartilaginous sheets from the control of cartilage thickness, a process which might be the evolutionary mechanism underlying adaptations of facial shape. In rod-shaped cartilage structures (Meckel, ribs and skeletal elements in developing limbs), the transverse integration of clonal columns determines the well-defined diameter and resulting rod-like morphology. We were able to alter cartilage shape by experimentally manipulating clonal geometries. Using in silico modeling, we discovered that anisotropic proliferation might explain cartilage bending and groove formation at the macro-scale.

DOI:http://dx.doi.org/10.7554/eLife.25902.001

Multiplex PCR and Microarray for Detection of Swine Respiratory Pathogens

Porcine respiratory disease complex (PRDC) is one of the most important health concerns for pig producers and can involve multiple viral and bacterial pathogens. No simple, single‐reaction diagnostic test currently exists for the simultaneous detection of major pathogens commonly associated with PRDC. Furthermore, the detection of most of the bacterial pathogens implicated in PRDC currently requires time‐consuming culture‐based methods that can take several days to obtain results. In this study, a novel prototype automated microarray that integrates and automates all steps of post‐PCR microarray processing for the simultaneous detection and typing of eight bacteria and viruses commonly associated with PRDC is described along with associated multiplex reverse transcriptase PCR. The user‐friendly assay detected and differentiated between four viruses [porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus, porcine circovirus type 2, porcine respiratory corona virus], four bacteria (Mycoplasma hyopneumoniae, Pasteurella multocida, Salmonella enterica serovar Choleraesuis, Streptococcus suis), and further differentiated between type 1 and type 2 PRRSV as well as toxigenic and non‐toxigenic P. multocida. The assay accurately identified and typed a panel of 34 strains representing the eight targeted pathogens and was negative when tested with 34 relevant and/or closely related non‐target bacterial and viral species. All targets were also identified singly or in combination in a panel of clinical lung samples and/or experimentally inoculated biological material.

Insulated Isothermal Reverse Transcriptase PCR (iiRT-PCR) for Rapid and Sensitive Detection of Classical Swine Fever Virus

Classical swine fever (CSF) is an OIE‐listed disease that can have a severe impact on the swine industry. User‐friendly, sensitive, rapid diagnostic tests that utilize low‐cost field‐deployable instruments for CSF diagnosis can be useful for disease surveillance and outbreak monitoring. In this study, we describe validation of a new probe‐based insulated isothermal reverse transcriptase PCR (iiRT‐PCR) assay for rapid detection of classical swine fever virus (CSFV) on a compact, user‐friendly device (POCKIT^™ Nucleic Acid Analyzer) that does not need data interpretation by the user. The assay accurately detected CSFV RNA from a diverse panel of 33 CSFV strains representing all three genotypes plus an additional in vitro‐transcribed RNA from cloned sequences representing a vaccine strain. No cross‐reactivity was observed with a panel of 18 viruses associated with livestock including eight other pestivirus strains (bovine viral diarrhoea virus type 1 and type 2, border disease virus, HoBi atypical pestivirus), African swine fever virus, swine vesicular disease virus, swine influenza virus, porcine respiratory and reproductive syndrome virus, porcine circovirus 1, porcine circovirus 2, porcine respiratory coronavirus, vesicular exanthema of swine virus, bovine herpes virus type 1 and vesicular stomatitis virus. The iiRT‐PCR assay accurately detected CSFV as early as 2 days post‐inoculation in RNA extracted from serum samples of experimentally infected pigs, before appearance of clinical signs. The limit of detection (LOD_95%) calculated by probit regression analysis was 23 copies per reaction. The assay has a sample to answer turnaround time of less than an hour using extracted RNA or diluted or low volume of neat serum. The user‐friendly, compact device that automatically analyses and displays results could potentially be a useful tool for surveillance and monitoring of CSF in a disease outbreak.

Expression patterns of calretinin, calbindin and parvalbumin and their colocalization in neurons during development of Macaca monkey retina

The developmental expression of calbindin (CalB), calretinin (CaR) and parvalbumin (PV) was followed in Macaca monkey retina using single and double immunolabeling to identify which proteins provide distinctive labels for specific cell types and to clarify the role of these proteins during development. Ganglion cells (GC) expressed PV at fetal day (Fd)55 and CaR and CalB by Fd85. CaR was downregulated after birth. Separate subsets of amacrine (AM) cells expressed CaR and CalB at Fd65-70. After Fd115, many CaR+ AM coexpressed CalB. After Fd120 a few AM expressed PV and these added CaR and CalB after birth. A subset of horizontal cells (HZ) expressed CaR and CalB at Fd70. Slightly later all HZ express PV and CaR while the early subset is CalB+/PV+/CaR+. CaR downregulates in all HZ after birth. The DB3 cone bipolar cells (BP) under the HZ label for CalB by Fd90-110 while a probable OFF BP cell body just above the AM layer becomes CaR+ near birth with labeling increasing after birth. All cones outside of the fovea label for CalB by Fd125. Foveal cones, rods, most BP and Müller glia do not label for these proteins at any age. The complex patterns of up- and down-regulation found in Macaca retina are similar to previous reports of expression in human retina, but in many instances are quite different than earlier reports of CaR, CalB and PV expression patterns in monkey central visual centers. This makes it highly likely that each protein plays a specific but undetermined role(s) in each visual center, and that its expression is controlled at a given stage of retinal development by multiple intrinsic and extrinsic factors.

Leucocytoclastic vasculitis: an update for the clinician

Leucocytoclastic vasculitis is a small vessel inflammatory disease mediated mostly by deposition of immune complexes. Infections, medications, chemicals, bacteria, viruses, and diseases associated with immune complexes have been accused in the pathogenesis. Cutaneous leucocytoclastic vasculitis presents as palpable purpura most often localized in the lower extremities, often accompanied by abdominal pain, arthralgia and renal involvement. The clinical diagnosis of leucocytoclastic vasculitis is confirmed histopathologically by skin biopsy. In order to determine the cause of the disease, depending on the patient's history, complete blood cell count, blood cultures, cryoglobulins, serum protein electrophoresis, rheumatoid factor, antinuclear antibody, and autoantibodies to neutrophilic cytoplasmic antigens and complement should be checked. Once the diagnosis of leucocytoclastic vasculitis is made, emphasis should be on the search for an etiological factor and the identification of the involved organs. If possible, the underlying cause should be treated or removed, for example discontinuation of drugs. The prognosis depends on the disease that has the cutaneous leucocytoclastic angiitis as a component, as well as the severity of internal organ involvement. For example, a patient with cutaneous leucocytoclastic angiitis and moderate nephritis as component of Henoch-Schonlein purpura has a much better prognosis than a patient with these same findings as a component of Wegener's granulomatosis. Only if physicians recognize and report severe reactions to regulatory authorities and manufacturers, new drugs associated with a risk of such reactions can be identified.

Oral arginine improves blood pressure in renal transplant and hemodialysis patients

BACKGROUND

Hypertension in kidney transplant (KT) patients may result from attenuated whole-body nitric oxide (NO) content and abnormal NO-mediated vasodilation. Increasing NO bioavailability with L-arginine (ARG) could theoretically restore the NO-mediated vasodilatory response and lower blood pressure.

METHODS

In a prospective pilot study, 6 normotensive volunteers and 10 KT patients received oral supplements of ARG (9.0 g/d) for 9 days, then 18.0 g/d for 9 more days. Six hemodialysis (HD) and 4 peritoneal dialysis patients received the same dose for 14 days. Five KT patients received 30 mL/d of canola oil (CanO) in addition to ARG. Systolic (SBP) and diastolic (DBP) blood pressure, creatinine clearance (CCr), and serum creatinine (Cr) were measured at baseline, day 9, and day 18. In a subsequent study, 20 hypertensive KT patients with stable but abnormal renal function were randomized in a crossover study to start ARG-only or ARG+CanO supplements for two 2-month periods with an intervening month of no supplementation. SBP, DBP, CCr, and Cr were measured monthly for 7 months.

RESULTS

In the pilot study, ARG reduced the SBP in HD patients from 171.5 +/- 7.5 mmHg (baseline) to 142.8 +/- 8.3 mmHg (p = .028). In the crossover study, SBP was reduced from baseline (155.9 +/- 5.0 mmHg), after the first 2 months (143.2 +/- 3.2 mmHg; p = .03) and subsequent 2 months (143.3 +/- 2.5 mmHg; p = .014) of supplementation. DBP was also reduced after supplementation in both studies. CanO had no effect on blood pressure. Renal function did not change.

CONCLUSIONS

Oral preparations of ARG (+/-CanO) were well tolerated for up to 60 consecutive days and had favorable effects on SBP and DBP in hypertensive KT and HD patients.

Cutaneous leucocytoclastic vasculitis associated with oxacillin

A 67-year-old man who was treated with oxacillin for one week because of Staphylococcus aureus bacteremia, developed renal failure and diffuse, symmetric, palpable purpuric lesions on his feet. Necrotic blisters were noted on his fingers. Skin biopsies showed findings diagnostic of leucocytoclastic vasculitis. Oxacillin was discontinued and patient was treated with corticosteroids. The rash disappeared after three weeks and renal function returned to normal. Leucocytoclastic vasculitis presents as palpable purpura of the lower extremities often accompanied by abdominal pain, arthralgia, and renal involvement. Etiologic factors or associated disorders include infections, medications, collagen vascular disease and neoplasia. However, in half of the cases no etiologic factor is identified. Usually it is a self-limited disorder, but corticosteroid therapy may be needed in life-threatening cases since early treatment with corticosteroids in severe cases can prevent complications. Oxacillin should be included among the drugs that can cause leucocytoclastic vasculitis.

The spatial and temporal expression of outer segment proteins during development of Macaca monkey cones

PURPOSE

To characterize the spatial and temporal expression of key structural and phototransduction cascade proteins in the monkey cone outer segment (OS).

METHODS

Retinas from Macaca monkeys from ages fetal day (Fd) 89 through adulthood were double labeled using immunofluorescence for short (S) or long/medium (L/M) wavelength-sensitive cone opsin and either a structural protein (peripherin) or a phototransduction cascade protein (alpha-transducin [alpha-T], phosphodiesterase [PDE], or rhodopsin kinase [RK]). The spatial and temporal patterns of expression for each protein at each age were determined and graphed as a percentage of retinal coverage.

RESULTS

In both cone types, opsins and phototransduction proteins appear first in the fovea and last at the retinal edge. Peripherin appears concomitantly with opsin in both S and L/M cones, but S cones express peripherin and opsin 1 to 3 weeks before neighboring L/M cones. Alpha-T, PDE, and RK are expressed together in the L/M cone OS shortly after L/M opsin appears. Phototransduction proteins are not expressed in S cones until 1 to 3 weeks after the appearance of S opsin and at the same time that neighboring cones are expressing both L/M opsin and phototransduction proteins.

CONCLUSIONS

The concomitant appearance of opsin and peripherin strongly suggests roles in promoting the structural integrity of the developing OS. Phototransduction cascade proteins appear in the developing OS at the same time as one another, but after opsin. The significant lag between their expression and that of S cone opsin indicates that phototransduction proteins are not essential for OS formation, nor does opsin expression trigger their expression. The different temporal but similar spatial expression patterns of phototransduction proteins within S and L/M cones suggests that some local signal(s) coordinates their appearance.

Hepatitis C virus envelope glycoprotein E1 originates in the endoplasmic reticulum and requires cytoplasmic processing for presentation by class I MHC molecules

We investigated whether hepatitis C virus envelope glycoprotein E1 is transported from the endoplasmic reticulum (ER) to the cytoplasm of infected cells for class I MHC processing. Target cells expressing E1 were killed by CTL lines from a hepatitis C virus-infected chimpanzee, and synthetic peptides were used to define an epitope (amino acids 233-GNASRCWVA-241) presented by the Patr-B*1601 class I MHC molecule. An unusually high concentration (>100 nM) of this nonameric peptide was required for target cell lysis, but this could be reduced at least 1000-fold by replacing the asparagine at amino acid position 234 (Asn234) with aspartic acid (Asp), the anticipated anchor residue for NH2-terminal peptide binding to Patr-B*1601. Conspicuously, position 234 is part of an N-glycosylation motif (Asn-Xaa-Ser/Thr), suggesting that the Asn234 to Asp substitution might occur naturally within the cell due to deglycosylation/deamidation of this amino acid by the cytosolic enzyme peptide N-glycanase. In support of this model, we demonstrate that presentation of the epitope depended on 1) cotranslational synthesis of E1 in the ER, 2) glycosylation of the E1 molecule, and 3) a functional TAP transporter to shuttle peptide from the cytosolic to ER compartment. These results indicate for the first time that during infection of the host, viral envelope glycoproteins originating in the ER are processed in the cytoplasm for class I MHC presentation. That a posttranslational change in amino acid sequence from Asn to Asp alters the repertoire of peptides presented to CD8+ CTL has implications for the design of antiviral vaccines.

Norepinephrine induced growth and expression of virulence associated factors in enterotoxigenic and enterohemorrhagic strains of Escherichia coli

The small intestine is richly innervated by the sympathetic nervous system. High concentrations of monoamines, most notably norepinephrine, are found throughout the various intestinal layers. In order to determine whether norepinephrine is capable of influencing bacterial pathogenesis, the growth and production of virulence factors in ETEC and EHEC were examined in a physiologically relevant medium utilizing very low initial bacterial inoculums to more closely mimie in vivo conditions. The growth of ETEC strain B44 and the production of the K99 pilus adhesin on a protein equivalent basis was greatly increased in the presence of norepinephrine. Growth of EHEC O157:H7 was also increased in norepinephrine containing medium as well as production of SLT-I and SLT-II. The ability of norepinephrine to increase both bacterial growth and expression of virulence factors was shown to be non-nutritional in nature. Given the abundant adrenergic innervation in the small intestine, these in vitro results suggest that the neurohumoral environment of the host may play a role in bacterial growth and expression of virulence factors.

Purification and characterization of recombinant cystic fibrosis transmembrane conductance regulator from Chinese hamster ovary and insect cells

We have developed procedures to purify highly functional recombinant cystic fibrosis transmembrane conductance regulator (CFTR) from Chinese hamster ovary (CHO) cells to high homogeneity. Purification of CHO-CFTR was achieved using a combination of alkali stripping, alpha-lysophosphatidylcholine extraction, DEAE ion-exchange, and immunoaffinity chromatography. Insect CFTR from Sf9 cells was purified using a modification of the method of Bear et al. (Bear, C. E., Li, C., Kartner, N., Bridges, R. J., Jensen, T. J., Ramjeesingh, M. and Riordan, J. R. (1992) Cell 68, 809-818), which included extraction with sodium dodecyl sulfate, hydroxyapatite, and gel filtration chromatography. Characterization of the properties of purified CFTR from both cell sources using a variety of electrophysiological and biochemical assays indicated that they were very similar. Both the purified CHO-CFTR and Sf9-CFTR when reconstituted into planar lipid bilayers exhibited a low pS, chloride-selective ion channel activity that was protein kinase A- and ATP-dependent. Both the purified CHO-CFTR and Sf9-CFTR were able to interact specifically with the nucleotide photoanalogue 8-N3-[alpha-32P]ATP with half-maximal binding at 25 and 50 microM, respectively. These values compare well with those reported for 8-N3-[alpha-32P]ATP binding to CFTR in its native membrane form. Thus CFTR from either insect or CHO cells can be purified to high homogeneity with retention of many of the biochemical and electrophysiological characteristics of the protein associated in its native plasma membrane form. The availability of these reagents will facilitate further investigation and study of the structure and function of CFTR and its interactions with cellular proteins.

Piperacillin/tazobactam compared with ticarcillin/clavulanate in community-acquired bacterial lower respiratory tract infection

The efficacy and safety of a new combination parenteral antibiotic, piperacillin/tazobactam, was compared with that of parenteral ticarcillin/clavulanate in the treatment of adult patients with community-acquired lower respiratory tract infections. A total of 299 patients were enrolled in this multicentre, double-blind, comparative study; 177 received piperacillin/tazobactam and 122 received ticarcillin/clavulanate. Of these, 119 met the evaluability criteria (69, piperacillin/tazobactam and 50, ticarcillin/clavulanate). The study drugs (piperacillin/tazobactam 3 g/375 mg or ticarcillin/clavulanate 3 g/100 mg) were given every 6 h by slow iv infusion for a minimum of 5 days. The favourable clinical response (cured and improved) rates of evaluable patients were 84% and 64% at endpoint (P < 0.01) for piperacillin/tazobactam and ticarcillin/clavulanate, respectively. The favourable bacteriological response at the early follow-up (eradicated and presumed eradicated) were 91% and 67% for piperacillin/tazobactam and ticarcillin/clavulanate, respectively (P < 0.01). At endpoint, 84% and 64%, respectively (P = 0.02) had a favourable response. The most common adverse experiences involved the gastrointestinal tract and occurred in 31.6% of the piperacillin/tazobactam group compared with 20.5% in the ticarcillin/clavulanate group (P = 0.02). These events were mild and generally did not affect therapy. Piperacillin/tazobactam appears to be more effective than ticarcillin/clavulanate in this patient population and is generally well tolerated.

Coincidental appearance of the alpha 1 subunit of the GABA-A receptor and the type I benzodiazepine receptor near birth in macaque monkey visual cortex

The expression of subtypes of the GABA-A/benzodiazepine receptor complex has been studied during pre- and postnatal development of Macaca monkey visual cortex using complementary radioligand and immunocytochemical labeling. Type I benzodiazepine receptors were labeled directly by [3H]zolpidem. Type II receptors were determined by the amount of binding for [3H]flunitrazepam (FZ) persisting in the presence of the type I-specific ligand CL218872. Monoclonal antibody bd24 was used to label alpha 1 subunits and bd17 to label beta 2 and beta 3 subunits of the GABA-A receptor. Radioligand binding data and bd17 immunoreactivity indicated that type II benzodiazepine receptors were present by fetal day (Fd) 74 (44% of gestation). Immunoreactivity for the beta 2/beta 3 subunits increased until 3-6 weeks after birth, and then declined somewhat into adulthood. Neither radioligand labeling for type I receptors nor immunocytochemical staining for the alpha 1 subunit were apparent until mid-gestation. Both markers appeared shortly before birth in layer 4C, and then in other cortical layers after birth. Immunoreactivity for the alpha 1 subunit increased steadily after birth until it became more intense than that for beta 2/3 subunits in the adult. Quantitative densitometry of CL218872 competition for [3H]FZ binding showed that type I/II distribution was 22%/78% at Fd103; 42%/58% at Fd131; 67%/33% at 9 months; and 61%/39% in adult visual cortex. This "switch" between benzodiazepine receptor subtypes overlaps the postnatal critical period for geniculostriate development, suggesting that the change from type II to type I receptors and the appearance of alpha 1 subunits may play a decisive role in the maturation of geniculocortical axon terminations and cortical response properties. It remains to be shown whether this "switch" is dependent on functional visual input.

Differential localization of two glutamic acid decarboxylases (GAD65 and GAD67) in adult monkey visual cortex

Adult monkey primary visual cortex contains a diverse population of stellate neurons that utilize the neurotransmitter gamma aminobutyric acid (GABA). Two glutamic acid decarboxylase (GAD) enzymes that synthesize GABA, GAD65 and GAD67, were localized within these stellate neurons by in situ hybridization of 35S or digoxigenin (DIG) labeled riboprobes. Double labels were done by using 35S GAD67 riboprobe and GABA immunocytochemistry on the same section to verify that the neuronal population identified by immunocytochemistry was the same one studied in the in situ hybridization experiments. We find that GAD65 mRNA and GAD67 mRNA are widely distributed in the cortex, with four bands of heavily labeled neurons in upper layer 2, lower 3, 4C, and 6. GAD67 labeled neurons were more obvious in layer 4C beta, while GAD65 containing neurons were common in layer 1 and white matter. Northern blots and in situ hybridization on sections with both 35S and DIG riboprobes indicate that cortical neurons typically contain more GAD67 mRNA. Cell counts show that 18% of all cortical neurons contain GAD67 mRNA and 13% contain GAD65 mRNA, suggesting that a small population of GABA neurons might lack GAD65. Cell bodies that contain high amounts of GAD65 mRNA are prominent in layers deep 3, 4B, 4C alpha, and 6 and often are the largest cells in their respective layers. Double labels demonstrate that 96% of all GABA+ neurons contain GAD67 mRNA. Neurons heavily labeled for GABA tend to have smaller cell bodies and contain less GAD67 mRNA, while lightly labeled GABA neurons are larger and contain more GAD67 mRNA. These data indicate that most GABA neurons in monkey striate cortex contain both GAD enzymes. Although the differences in GABA content, cell size, laminar distribution, and GAD mRNA concentration suggest different requirements for GAD67 and GAD65 in cortical circuits, our experiments do not reveal what different roles these two enzymes subserve within GABAergic stellate neurons.

Light and electron microscopic analysis of synaptic development in Macaca monkey retina as detected by immunocytochemical labeling for the synaptic vesicle protein, SV2

The development of synapses has been followed in Macaca monkey fetal and infant retina using immunocytochemical labeling for the transmembrane synaptic vesicle glycoprotein, SV2. Electron microscopy (EM) was used to verify the presence of morphological synapses at selected ages. EM immunocytochemical labeling in adult retina showed that all synaptic types contained SV2 in inner (IPL) and outer (OPL) plexiform layers. In fetal retina, SV2 expression and the appearance of morphological synapses were closely related in time, demonstrating that SV2 is a reliable marker for synaptogenesis. SV2 expression appears along a foveal to peripheral gradient. Both SV2 and synapses appear in the foveal IPL at Fd50-55, and reach the retinal edge by Fd90-103. Cone ribbon synapses and SV2 labeling are not present in the foveal OPL until Fd60. Photoreceptors in the far periphery contain SV2 by Fd119-125. This pattern demonstrates an "inner to outer" direction of synaptogenesis. Cones show SV2 labeling before rods at the same retinal eccentricity. In the cone-dominated fovea, SV2 labeling and bipolar cell ribbon-containing terminals are present at Fd55 when amacrine cell conventional terminals are very scarce, indicating that bipolar synapses precede amacrine synapses in monkey foveal IPL. SV2 labeling and bipolar terminals appear first in the outer IPL which contains "OFF" ganglion and bipolar processes in the adult, suggesting that "OFF" midget bipolar cells may form the first synapses. Both SV2 immunocytochemical labeling and EM morphology find that monkey retina follows a generalized inner before outer, and cone before rod synaptic developmental pattern, similar to that in other mammals. The cone-dominated fovea initiates synaptogenesis, and shows a different synaptic sequence from rod-dominated peripheral retina.

The long-term prevention of tobacco use among junior high school students: classroom and telephone interventions

OBJECTIVES

The purpose of this study was to implement and evaluate the effectiveness of a long-term tobacco use prevention program for junior high school students that used college undergraduate change agents and telephone boosters.

METHODS

A psychosocial intervention combining refusal skills training, contingency management, and other tobacco use prevention methodologies such as telephone and mail boosters was implemented in 11 junior high schools in San Diego County, California. Eleven other junior high schools served as controls. Of the 2668 participants, 57% were White/non-Hispanic, 24% were Hispanic, and 19% were of other racial/ethnic groups. College undergraduates served as change agents for both the classroom and booster interventions, the latter of which was delivered in the third (ninth-grade) year of the program.

RESULTS

At the end of the third year, the prevalence of tobacco use within the past month was 14.2% among the intervention students and 22.5% among the controls, yielding an odds ratio of 0.71 for analysis at the school level.

CONCLUSIONS

Both college undergraduate change agents and direct one-to-one telephone interventions appear to provide cost-effective tobacco-related behavior modification.