Spatiotemporal characteristics of ozone and the formation sensitivity over the Fenwei Plain

High surface ozone (O₃) levels affect human and environmental health. The Fenwei Plain (FWP), one of the critical regions for China's "Blue Sky Protection Campaign", has reported severe O₃ pollution. This study investigates the spatiotemporal properties and the causes of O₃ pollution over the FWP using high-resolution data from the TROPOspheric Monitoring Instrument (TROPOMI) from 2019 to 2021. This study characterizes spatial and temporal variations in O₃ concentration by linking O₃ columns and surface monitoring using a trained deep forest machine learning model. O₃ concentrations in summer were 2-3 times higher than those found in winter due to higher temperatures and greater solar irradiation. The spatial distributions of O₃ correlate with the solar radiation showing decreased trends from the northeastern to the southwestern FWP, with the highest O₃ values in Shanxi Province and the lowest in Shaanxi Province. For urban areas, croplands and grasslands, the O₃ photochemistry in summer is NO_x-limited or in the transitional regime, while it is VOC-limited in winter and other seasons. Reducing NO_x emissions would be effective for decreasing O₃ levels in summer, while VOC reductions are necessary for winter. The annual cycle in vegetated areas included both NO_x-limited and transitional regimes, indicating the importance of NO_x controls to protect ecosystems. The O₃ response to limiting precursors shown here is of importance for optimizing control strategies and is illustrated by emission changes during the 2020 COVID-19 outbreak.

Prediction of Neurodevelopmental Disorders Based on De Novo Coding Variation

The early detection of neurodevelopmental disorders (NDDs) can significantly improve patient outcomes. The differential burden of non-synonymous de novo mutation among NDD cases and controls indicates that de novo coding variation can be used to identify a subset of samples that will likely display an NDD phenotype. Thus, we have developed an approach for the accurate prediction of NDDs with very low false positive rate (FPR) using de novo coding variation for a small subset of cases. We use a shallow neural network that integrates de novo likely gene-disruptive and missense variants, measures of gene constraint, and conservation information to predict a small subset of NDD cases at very low FPR and prioritizes NDD risk genes for future clinical study.

MAGI-MS: multiple seed-centric module discovery

Summary

Complex disorders manifest by the interaction of multiple genetic and environmental factors. Through the construction of genetic modules that consist of highly coexpressed genes, it is possible to identify genes that participate in common biological pathways relevant to specific phenotypes. We have previously developed tools MAGI and MAGI-S for genetic module discovery by incorporating coexpression and protein interaction networks. Here, we introduce an extension to MAGI-S, denoted as Merging Affected Genes into Integrated Networks-Multiple Seeds (MAGI-MS), which permits the user to further specify a disease pathway of interest by selecting multiple seed genes likely to function in the same molecular mechanism. By providing MAGI-MS with seed genes involved in processes underlying certain classes of neurodevelopmental disorders, such as epilepsy, we demonstrate that MAGI-MS can reveal modules enriched in genes relevant to chemical synaptic transmission, glutamatergic synapse and other functions associated with the provided seed genes.

Availability and implementation

MAGI-MS is free and available at https://github.com/jchow32/MAGI-MS.

Supplementary information

Supplementary data are available at Bioinformatics Advances online.

His resynchronization therapy produces more physiological ventricular repolarisation compared with biventricular pacing

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

BACKGROUND

Biventricular pacing (BVP) is known to shorten activation time in patients with heart failure and left bundle branch block (LBBB) but its effects on repolarisation are not well studied. His bundle pacing (HBP) can correct LBBB to deliver cardiac resynchronization therapy (HBP-CRT), producing more physiological ventricular activation time and pattern than BVP. It is not known whether this translates to more physiological repolarisation, and if so whether the effect is mediated through its effects on activation.

PURPOSE

We measured the effects of HBP-CRT and BVP on left ventricular repolarisation using non-invasive epicardial mapping (ECGI).

METHODS

Patients were recruited in two groups. 1) Patients scheduled for clinically indicated BVP procedures for heart failure with LBBB, 2) Individuals with narrow QRS, normal ventricular function and intact conduction systems. Using non-invasive electrocardiographic imaging, we identified patients with LBBB in whom HBP shortened ECGI-derived left ventricular (LV) activation time by >10ms. We compared the effects of HBP and BVP on ECGI-derived dispersion of LV repolarisation times and activation-recovery intervals (a surrogate for action potential duration).

RESULTS

21 patients in whom HBP shortened LV activation time by >10ms and an equal number of individuals with narrow intrinsic QRS were recruited. LV repolarisation dispersion was reduced by HBP-CRT (-42.0 ms, 95% confidence interval (CI): -52.3 to -31.7 ms, p <0.001) but not by BVP (11.9 ms, 95% CI: -6.24 to 30.1 ms, p = 0.182). The mean within-patient change in LV repolarisation dispersion from BVP to HBP-CRT was -56.5 ms (95% CI: -70.5 to -42.5 ms, p < 0.001). LV repolarisation dispersion with HBP-CRT was not different from individuals with narrow intrinsic QRS (2.75 ms, 95% CI: -16.2 to 21.7 ms, p = 0.981). The magnitude of reduction in LV repolarisation dispersion with HBP-CRT from intrinsic LBBB appeared similar to the magnitude of LV activation time shortening (-54.9 ms, 95% CI: -68.2 to -41.6 ms, p < 0.001). However, LV activation-recovery interval dispersion was also reduced by HBP-CRT (-44.3 ms, 95% CI: -69.2 to -19.3 ms, p < 0.001). Repolarisation mapping demonstrated normalisation of repolarisation pattern by HBP-CRT.

CONCLUSIONS

HBP-CRT can normalise repolarisation dispersion, producing more physiological repolarisation compared with BVP, which does not resolve the repolarisation abnormality of LBBB. HBP-CRT improves repolarisation through both activation resynchronization and modulation of action-potential duration. If these acute results translate to longer term outcomes, HBP-CRT may reduce the risk of ventricular arrhythmias in heart failure with LBBB to a greater extent than BVP. Abstract Figure. Epicardial Repolarisation Maps

Sea Turtle Population Genomic Discovery: Global and Locus-Specific Signatures of Polymorphism, Selection, and Adaptive Potential

In the era of genomics, single-nucleotide polymorphisms (SNPs) have become a preferred molecular marker to study signatures of selection and population structure and to enable improved population monitoring and conservation of vulnerable populations. We apply a SNP calling pipeline to assess population differentiation, visualize linkage disequilibrium, and identify loci with sex-specific genotypes of 45 loggerhead sea turtles (Caretta caretta) sampled from the southeastern coast of the United States, including 42 individuals experimentally confirmed for gonadal sex. By performing reference-based SNP calling in independent runs of Stacks, 3,901–6,998 SNPs and up to 30 potentially sex-specific genotypes were identified. Up to 68 pairs of loci were found to be in complete linkage disequilibrium, potentially indicating regions of natural selection and adaptive evolution. This study provides a valuable SNP diagnostic workflow and a large body of new biomarkers for guiding targeted studies of sea turtle genome evolution and for managing legally protected nonmodel iconic species that have high economic and ecological importance but limited genomic resources.

Concentrations and source contributions of particulate organic matter before and after implementation of a low emission zone in Munich, Germany

Within the Munich low emission zone (LEZ), samples of PM(2.5) were collected before (2006/2007) and after (2009/2010) the implementation of the LEZ. The samples were analyzed for carbon fraction (EC/OC) and particulate organic compounds (POC). Significant lower concentrations were noticed for elemental carbon (EC) and some of the POC like vanillic acid, acetosyringone, syringylacetone and syringic acid after the implementation of the LEZ. Higher concentrations of levoglucosan, retene and O-PAH were detected in the second sampling period. Positive matrix factorization (PMF) was used to identify the main sources of POC. Emissions from traffic, solid fuels combustion, cooking and mixed source were separated. The contribution of traffic source factor was decreased about 60% after the implementation of the LEZ. Thus the average concentration of EC from traffic factor decreased from 1.1 to 0.5 μg/m(3) after the implementation of the LEZ.

Characteristics and source apportionment of PM1 emissions at a roadside station

The mass concentrations of PM(1) (particles less than 1.0 μm in aerodynamic diameter), organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 25 elements were reported for 24h aerosol samples collected every sixth day at a roadside sampling station in Hong Kong from October 2004 to September 2005. Annual average PM(1) mass concentration was 44.5 ± 19.5 μg m(-3). EC, OM (organic matter, OC × 1.2), and SO(4)(=) were the dominant components, accounting for ∼ 36%, ∼ 26%, and ∼ 24% of PM(1), respectively. Other components, i.e., NO(3)(-), NH(4)(+), geological material, trace elements and unidentified material, comprised the remaining ∼ 14%. Annual average OC/EC ratio (0.6 ± 0.3) was low, indicating that primary vehicle exhaust was the major source of carbonaceous aerosols. The seasonal variations of pollutants were due to gas-particle partitioning processes or a change in air mass rather than secondary aerosol produced locally. Vehicle exhaust, secondary aerosols, and waste incinerator/biomass burning were dominant air pollution sources, accounting for ∼ 38%, ∼ 22% and ∼ 16% of PM(1), respectively. Pollution episodes during summer (May-August) which were frequently accompanied by tropical storms or typhoons were dominated by vehicle emissions. During winter (November-February) pollution episodes coincided with northeasterly monsoons were characterized by secondary aerosols and incinerator/biomass burning emissions.

Chemically-speciated on-road PM(2.5) motor vehicle emission factors in Hong Kong

PM(2.5) (particle with an aerodynamic diameter less than 2.5microm) was measured in different microenvironments of Hong Kong (including one urban tunnel, one Hong Kong/Mainland boundary roadside site, two urban roadside sites, and one urban ambient site) in 2003. The concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 40 elements (Na to U) were determined. The average PM(2.5) mass concentrations were 229+/-90, 129+/-95, 69+/-12, 49+/-18microg m(-3) in the urban tunnel, cross boundary roadside, urban roadside, and urban ambient environments, respectively. Carbonaceous particles (sum of organic material [OM] and EC) were the dominant constituents, on average, accounting for approximately 82% of PM(2.5) emissions in the tunnel, approximately 70% at the three roadside sites, and approximately 48% at the ambient site, respectively. The OC/EC ratios were 0.6+/-0.2 and 0.8+/-0.1 at the tunnel and roadside sites, respectively, suggesting carbonaceous aerosols were mainly from vehicle exhausts. Higher OC/EC ratio (1.9+/-0.7) occurred at the ambient site, indicating contributions from secondary organic aerosols. The PM(2.5) emission factor for on-road diesel-fueled vehicles in the urban area of Hong Kong was 257+/-31mg veh(-1) km(-1), with a composition of approximately 51% EC, approximately 26% OC, and approximately 9% SO(4)(=). The other inorganic ions and elements made up approximately 11% of the total PM(2.5) emissions. OC composed the largest fraction (approximately 51%) in gasoline and liquid petroleum gas (LPG) emissions, followed by EC (approximately 19%). Diesel engines showed higher emission rates than did gasoline and LPG engines for most pollutants, except for V, Br, Sb, and Ba.

The effect of acidification on the determination of elemental carbon, char-, and soot-elemental carbon in soils and sediments

We studied the influence of acid pretreatment on the effective distinction between elemental carbon (EC) and organic carbon (OC), and between char-EC and soot-EC. Though widely employed in the pretreatment of soils and sediments for EC quantification, the use of HCl, HF, and HNO(3) could decrease soot thermal stability as acid remains, leading to an underestimation of soot-EC by thermal methods. We compared thermal optical reflectance (TOR) measurements of EC concentrations in char reference materials and in lacustrine and marine sediments following pretreatment with various acids. The results showed that pretreatment with 2M HCl, concentrated HNO(3), 7 M HNO(3), and 1 M HNO(3) did not result in EC oxidation. However, hot concentrated HNO(3) oxidized EC significantly, leading to lower concentrations of EC, char-EC and soot-EC. By comparing the removal of potentially interfering materials, which contain little fire-derived carbon, with different acid pretreatments, we recommend the HCl-HF-HCl and concentrated (not hot) HNO(3)-HF-HCl pretreatments for the determination of EC, char-EC, and soot-EC in soils and sediments using the TOR method.

Indoor/outdoor relationships for PM2.5 and associated carbonaceous pollutants at residential homes in Hong Kong - case study

Six residences were selected (two roadside, two urban, and two rural) to evaluate the indoor-outdoor characteristics of PM(2.5) (aerodynamic diameter <2.5 microm) carbonaceous species in Hong Kong during March and April 2004. Twenty-minute-averaged indoor and outdoor PM(2.5) concentrations were recorded by DustTrak samplers simultaneously at each site for 3 days to examine diurnal variability of PM(2.5) mass concentrations and their indoor-to-outdoor (I/O) ratios. Daily (24-h average) indoor/outdoor PM(2.5) samples were collected on pre-fired quartz-fiber filters with battery-powered portable mini-volume samplers and analyzed for organic and elemental carbon (OC, EC) by thermal/optical reflectance (TOR) following the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. The average indoor and outdoor concentrations of 24 h PM(2.5) were 56.7 and 43.8 microg/m(3), respectively. The short-term PM(2.5) profiles indicated that the penetration of outdoor particles was an important contributor to indoor PM(2.5), and a household survey indicated that daily activities were also sources of episodic peaks in indoor PM(2.5). The average indoor OC and EC concentrations of 17.1 and 2.8 microg/m(3), respectively, accounted for an average of 29.5 and 5.2%, respectively, of indoor PM(2.5) mass. The average indoor OC/EC ratios were 5.8, 9.1, and 5.0 in roadside, urban, and rural areas, respectively; while average outdoor OC/EC ratios were 4.0, 4.3, and 4.0, respectively. The average I/O ratios of 24 h PM(2.5), OC, and EC were 1.4, 1.8, and 1.2, respectively. High indoor-outdoor correlations (r(2)) were found for PM(2.5) EC (0.96) and mass (0.81), and low correlations were found for OC (0.55), indicative of different organic carbon sources indoors. A simple model implied that about two-thirds of carbonaceous particles in indoor air are originated from outdoor sources.

PRACTICAL IMPLICATIONS

Indoor particulate pollution has received more attentions in Asia. This study presents a case study regarding the fine particulate matter and its carbonaceous compositions at six residential homes in Hong Kong. The characteristics and relationship of atmospheric organic and elemental carbon were discussed indoors and outdoors. The distribution of eight carbon fractions was first reported in indoor samples to interpret potential sources of indoor carbonaceous particles. The data set can provide significant scientific basis for indoor air quality and epidemiology study in Hong Kong and China.

Ectopic XIST transcripts in human somatic cells show variable expression and localization

XIST encodes a functional RNA that is expressed exclusively from the inactive X in female mammals and is required for the silencing of most of the genes on the chromosome. XIST transcripts remain in the nucleus, and their specific localization to the inactive X is important for silencing; however, it is not known how these transcripts localize to the inactive X chromosome. Expression of mouse and human XIST from ectopic sites has suggested that localization to the chromosome from which the gene is expressed may be dependent upon either the copy number of the integrated constructs or the level of ectopic XIST expression. To further examine the behavior of XIST transgenes when expressed from ectopic sites, we introduced an XIST-containing PAC into the human male somatic cell line HT-1080. In five different transformant clones, the degree of localization and associated DNA condensation of the surrounding chromatin varied within nuclei of the same clone, as well as among different clones. Comparing the number of integrated transgenes and the levels of XIST expression revealed that neither factor was sufficient for a tight localization of the XIST signal. Therefore, the extent of expression and localization of XIST transcripts from ectopic transgenes is likely dependent upon many interacting factors, including the number of integrated transgenes, the level of XIST expression, and the site of integration.

Forming facultative heterochromatin: silencing of an X chromosome in mammalian females

Compensating for the dosage difference in X-linked genes between male and female mammals involves the formation of an extremely stable heterochromatin structure on one of the two X chromosomes in females. The inactive X acquires numerous features of silent chromatin, including the expression of a noncoding RNA, a switch to late replication, histone modifications, recruitment of the histone variant macroH2A and DNA hypermethylation. Although the induction of inactivation in differentiating mouse embryonic stem cells suggests that the onset of each of these features appears to occur in a sequential manner, it is likely that there is a much more complex interplay between the different features which leads to the extremely stable silencing observed in female somatic cells. Expression of the untranslated RNA, XIST, is required in cis for the establishment of the heterochromatic state. Recent results have started to elucidate how expression of Xist is controlled, including the role of the antisense transcript Tsix.

Estimating middle-, neighborhood-, and urban-scale contributions to elemental carbon in Mexico City with a rapid response aethalometer

A successive moving average subtraction method is developed and applied to black carbon measured over 5-min intervals at a downtown location near many small emitters and at a suburban residential site within the urban plume but distant from specific emitters. Short-duration pulses assumed to originate from nearby sources are subtracted from the concentrations at each site and are summed to estimate middle-scale (approximately 0.1-1 km) contributions. The difference of the remaining baselines at the urban and suburban monitors is interpreted as the contribution to the downtown monitor from source emissions mixed over a neighborhood scale (1-5 km). The baseline at the suburban site is interpreted as the contribution of the mixture of black carbon sources for the entire city. When applied to a 24-day period from February and March 1997 in Mexico City, the analysis showed that 65% of the 24-hr black carbon was part of the urban mixture, 23% originated in the neighborhood surrounding the monitor, and only 12% was contributed from nearby sources. These analyses indicate that a fixed-site monitor can reasonably represent exposures in its surrounding neighborhood even when many local sources, such as exhaust from diesel buses and trucks, affect the monitor.

A confirmatory factor analysis of the BASIS-32 in racial and ethnic samples

The present study performed confirmatory factor analysis across major racial and ethnic groups of the BASIS-32, a measure of functional status of persons receiving mental health treatment and suitable for routine assessment mental health care. The purpose was to perform a preliminary investigation of cross-cultural equivalence in a county-level mental health program in a major metropolitan area. The results indicated a factor structure similar to that reported in the literature, and they suggested acceptable levels of agreement in structure between racial and ethnic minority groups and whites. The study revealed little reason to believe that the BASIS-32 varied in underlying structure across racial and ethnic boundaries, although further research is indicated.

Examination of chlorpromazine and other amphipathic drugs on the activity of lipopolysaccharide antagonists, E5564 and E5531

The synthetic antagonists of lipopolysaccharide (LPS), E5531 and E5564, are analogs of the lipid A portion of LPS that not only lack agonistic activity but also inhibit the biological effects of LPS both in vitro and in vivo. The effects of LPS and these synthetic antagonists have been localized to the recently described Toll-like receptor 4 (TLR4). A recent report indicated that the naturally occurring LPS antagonist Rhodobacter sphaeroides LPS loses its antagonist properties and gains pro-inflammatory qualities in the presence of chlorpromazine and other amphipathic drugs. To determine whether these reported actions occur with our chemically defined LPS antagonists, we examined the effects of chlorpromazine, fluphenazine, trifluoperazine, and lidocaine on the antagonism elicited by RsLPS and E5531 in U373 cells, which produce IL-6 in response to LPS. We also tested the effects of these amphipathic molecules on the LPS-neutralizing activity of RsLPS and E5564 on LPS-induced TNF-alpha release in human whole blood. The results indicate that neither chlorpromazine, fluphenazine, trifluoperazine nor lidocaine alter the activity of E5531 or E5564 in an in vitro cell system or human whole blood. Furthermore, chlorpromazine did not affect the antagonistic activity of RsLPS or E5564 on IL-6 generation by peripheral blood mononuclear cells. Thus, based on these data, our purified synthetic LPS-antagonists do not appear to lose their antagonistic properties and/or become agonists in the presence of amphipathic agents or drugs.

Arthroscopic osteochondral transplantation: Histologic results

PURPOSE

Localized, full-thickness articular cartilage defects of the femoral condyle are challenging. This report presents the histology of clinical cases obtained at intervals from 2 to 12 months after arthroscopic osteochondral transplantation.

TYPE OF STUDY

Longitudinal cohort study.

METHODS

Patients found at arthroscopy to have full-thickness femoral condyle defects between 1 and 3.5 cm in diameter underwent arthroscopic osteochondral transplantation. Exclusion criteria were associated tibial defects, patellar defects, or generalized arthritic change. The grafts taken from the superior and lateral intercondylar femoral notch were press-fit into holes drilled into the defect starting adjacent to the articular cartilage margin. Cancellous bone bridges were maintained between grafts. At various time intervals from 2 to 12 months after the osteochondral transplantation, arthroscopic biopsy specimens of the recipient sites were obtained.

RESULTS

Ten patients (5 male, 5 female) enrolled at 2 centers were evaluated arthroscopically at various intervals up to 13 months after osteochondral transplantation. The average patient age was 40 years (range, 17 to 65 years). One to 3 plugs had been harvested and inserted. Seven patients underwent biopsy at intervals ranging up to 12 months postoperatively. All showed maintenance of the integrity of the grafts with living chondrocytes and osteocytes. Donor sites filled without grafting and were covered with fibrocartilagenous scar. No complications occurred in this group.

CONCLUSIONS

These histologic results suggest that arthroscopic osteochondral transplantation is a viable alternative for treating full-thickness chondral defects, with the grafts retaining their integrity and living chondrocytes and osteocytes observed in the grafts for up to 12 months after implantation.

Sources of PM10 and sulfate aerosol at McMurdo Station, Antarctica

Source contributions to PM10 and sulfate aerosol at McMurdo Station, Antarctica during the austral summers of 1995-1996 and 1996-1997 were estimated using Chemical Mass Balance (CMB) receptor modeling. The average PM10 (particles with aerodynamic diameters less than 10 microm) concentration at Hut Point, located less than 1 km downwind of downtown McMurdo, was 3.4 microg/m3. Emissions profiles were determined for potentially important aerosol source types in McMurdo: exposed soil, power generation, space heating, and surface vehicles. Soil dust, sea salt, combustion emissions, sulfates, marine biogenic emissions as methanesulfonate, and nitrates contributed 57%, 15%, 14%, 10%, 3%, and 1%, respectively, of average estimated PM10 at Hut Point (3.2 microg/m3). Soil dust, sea salt, and combustion sources contributed 12%, 8%, and 20%, respectively, of the average PM10 sulfate concentration of 0.46 microg/m3. Marine biogenic sources contributed 0.17 microg/m3 (37%). The remaining sulfate is thought to have come from emissions from Mt. Erebus or hemispheric pollution sources.

Zones of representation for PM10 measurements along the US/Mexico border

The 'Imperial/Mexicali Valley Cross-Border PM10 Transport Study' acquired a database of meteorological and air quality measurements to determine source contributions to elevated PM10 concentrations and to estimate transport of PM10 between the US and Mexico. The study was conducted from 13 March 1992 to 29 August 1993, in a 80-km long by 20-km wide area spanning the US/Mexico border approximately 200 km inland from the coast of the Pacific Ocean, with monitoring sites located in the Imperial Valley on the US side and in the Mexicali Valley on the Mexico side. Measurements of PM 10 (particles with aerodynamic diameters less than 10 microm) mass, elements, water-soluble cations (i.e. sodium, potassium, ammonium) and anions (i.e. chloride, nitrate, sulfate), organic and elemental carbon and particle light absorption were acquired at two base sites on an every-sixth-day schedule supplemented by daily monitoring during winter and 4 times per day monitoring during intensive periods. Measurements were also taken at as many as 30 neighborhood (satellite) sites during week-long intensive monitoring periods in spring, summer and winter. This paper examines the zones of representation of long-term PM10 monitors by comparing their measurements with those from a spatially dense network of satellite sites. PM10 concentrations at the Mexicali site were consistently 30 to 50% higher than those observed at the Calexico site, even though the two sites were only 12 km apart. Distinct diurnal variations were found, with 6-h average PM10 concentrations often varying by a factor of 2 throughout the day - lowest during afternoon (12.00-18.00 h PST) and highest during night time (18.00-24.00 h PST). On average, crustal material accounted for 32-35% of annual-average PM10, carbonaceous aerosol for 20-30%, and ionic species for 8-10%. Levels of trace elements and sea salt were in the range of 1-4% of PM10. Significant concentration variations were found within the study area. PM10 concentrations in Mexico were double those in the US, decreasing with increasing northerly distance.

Source characterization of major emission sources in the imperial and Mexicali Valleys along the US/Mexico border

Chemical profiles for particle emissions are needed for source apportionment studies using the chemical mass balance (CMB) receptor model. Source measurements of geological sources, motor vehicle exhaust, vegetative burning (e.g. asparagus, field burning, charbroil cooking), and industrial sources (e.g. oil-fueled glass plant, manure-fueled power plants) were acquired as part of the Imperial/Mexicali Valley Cross Border PM10 Transport Study in 1992. Six different source sampling techniques (i.e. hot- and diluted-exhaust sampling, ground-based source sampling, particle sweeping/grab sampling, vacuum sampling, and laboratory resuspension sampling) were applied to acquire filter samples of PM 2.5 and PM10 (particulate matter with aerodynamic diameters < 2.5 and 10 microm, respectively). Filter samples were analyzed for mass by gravimetry, elements (Na to U) by X-ray fluorescence, anions (Cl(-), NO3(-), SO4(=)) by ion chromatography, ammonium (NH4(+)) by automated colorimetry, soluble sodium (Na+) and potassium (K+) by atomic absorption spectrophotometry, and organic and elemental carbon (OC, EC) by thermal/optical reflectance. Concentration data were acquired for a total of approximately 50 chemical species. Elevated abundances of crustal components (Al, Si, K, Ca, Fe) from geological material, carbon (OC, EC) and trace elements (Br, Pb) from vehicle exhausts, carbon (OC, EC) and ions (K(+), Cl(-)) from vegetative burning, ions (SO4(=), NH4(+), Na(+), K(+), Cl(-)) and elements (Cl, Se) from a manure-fueled power plants, and sulfur and trace elements (Na(+), Pb, Se, Ni, V) from an oil-fueled glass plant were found in the resulting source profiles. Abundances of crustal species (e.g. Al, Si, Ca) in the Imperial/Mexicali Valley geological profiles are more than twice those found in central and southern California. Abundances of lead in motor vehicle exhausts indicate different vehicle fleets in border cities. Emission profiles from field burning and charbroil cooking specific to the border area show that a majority (>60%) of emissions are comprised of carbon, with high organic to total carbon ratios (0.93 to 0.97). Abundances of sulfate and ammonium account for nearly 60% of the manure-fueled power plant's emissions. Elevated levels of metals (Na(+), Pb, Cd, Se) and byproducts of petroleum combustion (S, Ni, V) were found in the oil-fueled glass plant's emissions.

Aerosol chemical and optical properties during the Mt. Zirkel Visibility Study

Aerosol chemical and optical properties were measured near the Mt. Zirkel Wilderness Area in northwestern Colorado. Six-hour PM2.5 (particles with aerodynamic diameters less than 2.5 microm) mass concentrations and PM2.5 dry particle light scattering at 550 nm averaged 4.6 microg m(-3) and 8.6 Mm(-1), respectively. Sulfates, organic carbon, and geological material were the principle components of particle mass and light scattering. Hygroscopic growth was consistent with that expected for ammonium sulfate aerosols. Size distributions derived from three-wavelength (i.e., 450, 550, and 700 nm) nephelometer data were similar to those measured in other remote areas of the western USA. Quasi-dry chemical light scattering efficiencies derived using Mie theory were 3.6 m2 g(-1) for organic carbon, 2.5 m2 g(-1) for sulfates (ammonium sulfate and ammonium bisulfate), 2.6 m2 g(-1) for ammonium nitrate, and 1.76 m2 g(-1) for geological material. These values are lower than but consistent with previously reported results. Realistic efficiencies could not be derived using the multiple linear regression (MLR) approach.

Sustained endotoxemia leads to marked down-regulation of early steps in the insulin-signaling cascade

OBJECTIVES

To determine the effects of sustained, 3-day endotoxin infusion on early steps of the insulin-signaling pathway in rat liver and skeletal muscle in vivo; to examine insulin signaling in well-established acute endotoxin models of insulin resistance.

DESIGN

Prospective, controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Male Sprague-Dawley rats: 24 in the 3-day endotoxin study, 22 in each acute endotoxin study.

INTERVENTIONS

In prolonged endotoxemia studies, endotoxin (1 mg.kg-1.24 hrs-1) was administered via jugular venous catheter for 74 hrs. Insulin was then injected, and liver and skeletal muscle were removed after 5 mins. In acute endotoxemia studies, an endotoxin bolus (1 mg/kg) was administered, and insulin-signaling responses were studied after 4 hrs.

MEASUREMENTS AND MAIN RESULTS

In liver of rats with sustained endotoxemia, there were significant decreases in insulin-stimulated tyrosine phosphorylation of insulin receptors (74%), insulin receptor substrate (IRS)-1 (74%), and IRS2 (53%); binding of the p85 subunit of phosphatidylinositide 3-kinase to IRS1 (80%); and IRS1-precipitable phosphatidylinositide 3-kinase activity (>90%). These findings were associated with significant reductions in abundance of insulin receptors (37%), IRS1 (60%), and IRS2 (23%). Signaling in skeletal muscle was similarly affected, with reduced IRS1 phosphorylation (49%), IRS1 abundance (50%), and binding of p85 to IRS1 (57%). Insulin signaling 4 hrs after endotoxin administration was not different from controls.

CONCLUSIONS

Prolonged endotoxemia is associated with marked deficits in early steps of the insulin-signaling pathway, which are at least partly explained by reduced abundance of the insulin receptor and IRS proteins. Signaling defects were not evident 4 hrs after endotoxin administration under conditions of adequate nutrition, indicating that insulin resistance develops gradually, may require concomitant malnutrition, and is not reversed by the development of endotoxin tolerance.

PM2.5 and PM10 concentrations from the Qalabotjha low-smoke fuels macro-scale experiment in South Africa

This article presents results from the particulate monitoring campaign conducted at Qalabotjha in South Africa during the winter of 1997. Combustion of D-grade domestic coal and low-smoke fuels were compared in a residential neighborhood to evaluate the extent of air quality improvement by switching household cooking and heating fuels. Comparisons are drawn between the gravimetric results from the two types of filter substrates (Teflon-membrane and quartz-fiber) as well as between the integrated and continuous samplers. It is demonstrated that the quartz-fiber filters reported 5 to 10% greater particulate mass than the Teflon-membrane filters, mainly due to the adsorption of organic gases onto the quartz-fiber filters. Due to heating of sampling stream to 50 degrees C in the TEOM continuous sampler and the high volatile content of the samples, approximately 15% of the particulate mass was lost during sampling. The USEPA 24-hr PM2.5 and PM10 National Ambient Air Quality Standards (NAAQS) of 65 microg m(-3) and 150 microg m(-3), respectively, were exceeded on several occasions during the 30-day field campaign. Average PM concentrations are highest when D-grade domestic coal was used, and lowest between day 11 and day 20 of the experiment when a majority of the low-smoke fuels were phased in. Source impacts from residential coal combustion are also found to be influenced by changes in meteorology, especially wind velocity. PM2.5 and PM10 mass, elements, water-soluble cations (sodium, potassium, and ammonium), anions (chloride, nitrate, and sulfate), as well as organic and elemental carbon were measured on 15 selected days during the field campaign. PM2.5 constituted more than 85% of PM10 at three Qalabotjha residential sites, and more than 70% of PM10 at the gradient site in the adjacent community of Villiers. Carbonaceous aerosol is by far the most abundant component, accounting for more than half of PM mass at the three Qalabotjha sites, and for more than a third of PM mass at the gradient site. Secondary aerosols such as sulfate, nitrate, and ammonium are also significant, constituting 8 to 12% of PM mass at the three Qalabotjha sites and 15 to 20% at the Villiers gradient site.

PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995

PM2.5 (particles with aerodynamic diameters less than 2.5 microm) chemical source profiles applicable to speciated emissions inventories and receptor model source apportionment are reported for geological material, motor vehicle exhaust, residential coal (RCC) and wood combustion (RWC), forest fires, geothermal hot springs; and coal-fired power generation units from northwestern Colorado during 1995. Fuels and combustion conditions are similar to those of other communities of the inland western US. Coal-fired power station profiles differed substantially between different units using similar coals, with the major difference being lack of selenium in emissions from the only unit that was equipped with a dry limestone sulfur dioxide (SO2) scrubber. SO2 abundances relative to fine particle mass emissions in power plant emissions were seven to nine times higher than hydrogen sulfide (H2S) abundances from geothermal springs, and one to two orders of magnitude higher than SO2 abundances in RCC emissions, implying that the SO2 abundance is an important marker for primary particle contributions of non-aged coal-fired power station contributions. The sum of organic and elemental carbon ranged from 1% to 10% of fine particle mass in coal-fired power plant emissions, from 5% to 10% in geological material, >50% in forest fire emissions, >60% in RWC emissions, and >95% in RCC and vehicle exhaust emissions. Water-soluble potassium (K+) was most abundant in vegetative burning profiles. K+/K ratios ranged from 0.1 in geological material profiles to 0.9 in vegetative burning emissions, confirming previous observations that soluble potassium is a good marker for vegetative burning.

Black carbon aerosol at McMurdo Station, Antarctica

Aerosol light absorption as black carbon (BC) was measured from November 19, 1995, to February 6, 1996, at a location 0.65 km downwind of the center of McMurdo Station on the Antarctic coast. The results show a bimodal frequency distribution of BC concentrations. Approximately 65% of the measurements were found in a mode at a low range of concentrations centered at approximately 20 ng/m3. These concentrations are higher than those found at other remote Antarctic locations and probably represent contamination from the station. The remaining measurements were in a high-concentration mode (BC approximately 300 ng/m3), indicating direct impact of local emissions from combustion activities at the station. High values of BC were associated with winds from the direction of the station, and the BC flux showed a clear directionality. Maximum BC concentrations occurred between 7:00 and 11:00 a.m. The "polluted" mode accounted for more than 80% of the BC frequency-weighted impact at this location.

The extra domain A of fibronectin activates Toll-like receptor 4

Cellular fibronectin, which contains an alternatively spliced exon encoding type III repeat extra domain A (EDA), is produced in response to tissue injury. Fragments of fibronectin have been implicated in physiological and pathological processes, especially tissue remodeling associated with inflammation. Because EDA-containing fibronectin fragments produce cellular responses similar to those provoked by bacterial lipopolysaccharide (LPS), we examined the ability of recombinant EDA to activate Toll-like receptor 4 (TLR4), the signaling receptor stimulated by LPS. We found that recombinant EDA, but not other recombinant fibronectin domains, activates human TLR4 expressed in a cell type (HEK 293 cells) that normally lacks this Toll-like receptor. EDA stimulation of TLR4 was dependent upon co-expression of MD-2, a TLR4 accessory protein. Unlike LPS, the activity of EDA was heat-sensitive and persisted in the presence of the LPS-binding antibiotic polymyxin B and a potent LPS antagonist, E5564, which completely suppressed LPS activation of TLR4. These observations provided a mechanism by which EDA-containing fibronectin fragments promote expression of genes involved in the inflammatory response.

A novel synthetic acyclic lipid A-like agonist activates cells via the lipopolysaccharide/toll-like receptor 4 signaling pathway

ER-112022 is a novel acyclic synthetic lipid A analog that contains six symmetrically organized fatty acids on a noncarbohydrate backbone. Chinese hamster ovary (CHO)-K1 fibroblasts and U373 human astrocytoma cells do not respond to lipopolysaccharide (LPS) in the absence of CD14. In contrast, exposure to ER-112022 effectively induced activation of CHO and U373 cells under serum-free conditions. Expression of CD14 was not necessary for cells to respond to ER-112022, although the presence of soluble CD14 enhanced the sensitivity of the response. Several lines of evidence suggested that ER-112022 stimulates cells via the LPS signal transduction pathway. First, the diglucosamine-based LPS antagonists E5564 and E5531 blocked ER-112022-induced stimulation of CHO-K1, U373, and RAW264.7 cells. Second, ER-112022 was unable to activate C3H/HeJ mouse peritoneal macrophages, containing a mutation in Toll-like receptor (TLR) 4, as well as HEK293 cells, an epithelial cell line that does not express TLR4. Third, ER-112022 activated NF-kappaB in HEK293 cells transfected with TLR4/MD-2. Finally, tumor necrosis factor release from primary human monocytes exposed to ER-112022 was blocked by TLR4 antibodies but not by TLR2 antibodies. Our results suggest that ER-112022 and the family of lipid A-like LPS antagonists can functionally associate with TLR4 in the absence of CD14. Synthetic molecules like ER-112022 may prove to be valuable tools to characterize elements in the LPS receptor complex, as well as to activate or inhibit the TLR4 signaling pathway for therapeutic purposes.

Aqueous humor nitric oxide levels differ in patients with different types of glaucoma

Nitric oxide (NO) has effects on the regulation of aqueous humor dynamics, but the exact mechanism is not yet established. To investigate the possible roles of NO in glaucoma, we determined NO levels in aqueous humor and plasma in glaucoma patients and a control group, cataract patients. The study is an open trial with purposed sampling. One hundred fifty-two patients, including 87 glaucoma patients and 65 cataract patients from two medical centers, were recruited. NO levels in the samples were measured by a chemiluminescence assay. We found that, although the mean aqueous humor NO level (mean +/- SEM) was higher in the glaucoma patients than in the cataract patients (39.7 +/- 1.5 microM vs. 35.5 +/- 1.3 microM, p < 0.05), NO levels varied significantly in different types of glaucoma. The juvenile glaucoma patients had the lowest mean NO level (8.4 +/- 0.9 microM), while the acute angle-closure glaucoma and neovascular glaucoma patients had the highest mean NO levels (64.8 +/- 7.6 microM, 67.3 +/- 8.2 microM). In comparison, the mean plasma NO level in the glaucoma patients was not statistically different from that in the cataract patients (14.1 +/- 1.2 microM vs. 13.9 +/- 1.1 microM, p = 0.91). Our data may provide information for applying NO-mimicking nitrovasodilators in the treatment of glaucoma.

Light absorption by black sand dust

Light absorption by fine and coarse aerosols derived from Hawaiian black sand was determined by light transmission. The real part of the refractive index of this material was measured directly, and the imaginary part was estimated. The measured light absorption coefficients (B(ap)) were adjusted for multiple scattering artifacts by use of absorption-to-extinction ratios estimated with Mie theory. The best agreement between calculated and measured fine and coarse B(ap) was achieved with a value of 0.014 for the imaginary part of the refractive index. The corresponding absorption efficiencies for the fine and coarse black sand aerosols were 0.22 and 0.09 m(2)/g, respectively.

Air quality measurements from the Fresno Supersite

The Fresno Supersite intends to 1) evaluate non-routine monitoring methods, establishing their comparability with existing methods and their applicability to air quality planning, exposure assessment, and health effects studies; 2) provide a better understanding of aerosol characteristics, behavior, and sources to assist regulatory agencies in developing standards and strategies that protect public health; and 3) support studies that evaluate relationships between aerosol properties, co-factors, and observed health end-points. Supersite observables include in-situ, continuous, short-duration measurements of 1) PM2.5, PM10, and coarse (PM10 minus PM2.5) mass; 2) PM2.5 SO4(-2), NO3-, carbon, light absorption, and light extinction; 3) numbers of particles in discrete size bins ranging from 0.01 to approximately 10 microns; 4) criteria pollutant gases (O3, CO, NOx); 5) reactive gases (NO2, NOy, HNO3, peroxyacetyl nitrate [PAN], NH3); and 6) single particle characterization by time-of-flight mass spectrometry. Field sampling and laboratory analysis are applied for gaseous and particulate organic compounds (light hydrocarbons, heavy hydrocarbons, carbonyls, polycyclic aromatic hydrocarbons [PAH], and other semi-volatiles), and PM2.5 mass, elements, ions, and carbon. Observables common to other Supersites are 1) daily PM2.5 24-hr average mass with Federal Reference Method (FRM) samplers; 2) continuous hourly and 5-min average PM2.5 and PM10 mass with beta attenuation monitors (BAM) and tapered element oscillating microbalances (TEOM); 3) PM2.5 chemical speciation with a U.S. Environmental Protection Agency (EPA) speciation monitor and protocol; 4) coarse particle mass by dichotomous sampler and difference between PM10 and PM2.5 BAM and TEOM measurements; 5) coarse particle chemical composition; and 6) high sensitivity and time resolution scalar and vector wind speed, wind direction, temperature, relative humidity, barometric pressure, and solar radiation. The Fresno Supersite is coordinated with health and toxicological studies that will use these data in establishing relationships with asthma, other respiratory disease, and cardiovascular changes in human and animal subjects.

Cellular events mediated by lipopolysaccharide-stimulated toll-like receptor 4. MD-2 is required for activation of mitogen-activated protein kinases and Elk-1

Lipopolysaccharide (LPS) stimulates multiple signaling events, including nuclear factor-kappaB (NF-kappaB) activity and the mitogen-activated protein (MAP) kinases, ERK, JNK, and p38 in LPS-responsive cells, resulting in transcriptional activation and cytokine generation. LPS-induced signaling via toll-like receptor 4 (TLR4) results in the activation of the transcription factor NF-kappaB. Since LPS activates other signaling cascades in responsive cells, the objective of this study was to determine whether such events are mediated by TLR4 in response to LPS. We generated human embryonic kidney cells (HEK293) that stably express TLR4 (HEK-TLR4) and examined their responsiveness to LPS by measuring NF-kappaB activity and production of interleukin-8 (IL-8). A trans-reporting system was used to measure the activity of Elk-1, an ETS-domain transcription factor targeted by MAP kinase pathways. LPS stimulated NF-kappaB reporter activity and IL-8 production but not Elk-1 activity in HEK-TLR4 cells. When MD-2, a protein associated with the extracellular domain of TLR4, was expressed in these cells, there was a marked increase in Elk-1 activity as well as ERK, JNK, and p38 MAP kinase phosphorylation in response to LPS. TLR4-mediated NF-kappaB reporter activity and IL-8 production was enhanced by the expression of MD-2. This study demonstrates that expression of both TLR4 and MD-2 is required for LPS to activate or augment the MAP kinase pathways, Elk-1 stimulation, and IL-8 generation.

Particulate Air Pollution in Mexico City: A Collaborative Research Project

PM₁₀, PM₂₅, precursor gas, and upper-air meteorological measurements were taken in Mexico City, Mexico, from February 23 to March 22, 1997, to understand concentrations and chemical compositions of the city's particulate matter (PM). Average 24-hr PM₁₀ concentrations over the period of study at the core sites in the city were 75 H g/m³. The 24-hr standard of 150 μ g/m³ was exceeded for seven samples taken during the study period; the maximum 24-hr concentration measured was 542 μ g/m³. Nearly half of the PM₁₀ was composed of fugitive dust from roadways, construction, and bare land. About 50% of the PM₁₀ consisted of PM_2.5, with higher percentages during the morning hours. Organic and black carbon constituted up to half of the PM_2.5. PM concentrations were highest during the early morning and after sunset, when the mixed layers were shallow. Meteorological measurements taken during the field campaign show that on most days air was transported out of the Mexico City basin during the afternoon with little day-to-day carryover.

Use of public mental health services by Russian refugees

OBJECTIVES

This study identifies the demographic characteristics and patterns of mental health service use among Russian refugees in New York State.

METHODS

Data from a 1995 statewide survey of characteristics of patients served by the New York State mental health system were analyzed using chi square statistics and logistic regression.

RESULTS

The demographic characteristics and service-use patterns of Russian refugees are different from those of non-Russian refugees and non-refugees. Russian refugees who used mental health services were likely to be older women with major depression who were enrolled in Medicaid and who were using those services for the first time. Relying heavily on themselves, family members, or friends as referral sources, they tended to use exclusively individual, outpatient services at voluntary, nonprofit agencies.

CONCLUSIONS

Existing services systems must recognize the presence of Russian refugees. To improve access and service use, outreach efforts to the refugee community should be conducted, and services must be tailored to meet their mental health needs.

Middle- and Neighborhood-Scale Variations of PM10 Source Contributions in Las Vegas, Nevada

The Las Vegas Valley PM10 Study was conducted during 1995 to determine the contributions to PM10 aerosol from fugitive dust, motor vehicle exhaust, residential wood combustion, and secondary aerosol sources. Twenty-four-hr PM10 samples were collected at two neighborhood-scale sites every sixth day for 13 months. Five week-long intensive studies were conducted over a middle-scale sub-region at 29 locations that contained many construction projects emitting fugitive dust. The study found that the zone of influence around individual emitters was less than 1 km. Most of the sampling sites in residential and commercial areas yielded equivalent PM10 concentrations in the neighborhood region, even though they were more distant from each other than they were from the nearby construction sources. Based on chemical mass balance (CMB) receptor modeling, fugitive dust accounted for 80-90% of the PM10, and motor vehicle exhaust accounted for 3-9% of the PM10 in the Las Vegas Valley.

Endoscopic release of the carpal ligament for carpal tunnel syndrome: long-term results using the Chow technique

This report presents the author's experience with the Chow method for endoscopic release of the carpal ligament for carpal tunnel syndrome, with a minimum follow-up of 5 years. The report includes 116 cases (wrists) of 84 patients. The success rate for these cases is 93.3% and the recurrence rate is 0.96%. One temporary ulnar neuropraxia was reported in this group with spontaneous recovery. There were no permanent nerve injuries. Results of 5-year follow-up nerve conduction velocity tests are also included. This report shows that endoscopic release of the carpal ligament for carpal tunnel syndrome, using the Chow method, is a reliable alternative to the open procedure and has produced good, long-term, results.

Toll-like receptor-4 mediates lipopolysaccharide-induced signal transduction

TLR4 is a member of the recently identified Toll-like receptor family of proteins and has been putatively identified as Lps, the gene necessary for potent responses to lipopolysaccharide in mammals. In order to determine whether TLR4 is involved in lipopolysaccharide-induced activation of the nuclear factor-kappaB (NF-kappaB) pathway, HEK 293 cells were transiently transfected with human TLR4 cDNA and an NF-kappaB-dependent luciferase reporter plasmid followed by stimulation with lipopolysaccharide/CD14 complexes. The results demonstrate that lipopolysaccharide stimulates NF-kappaB-mediated gene expression in cells transfected with the TLR4 gene in a dose- and time-dependent fashion. Furthermore, E5531, a lipopolysaccharide antagonist, blocked TLR4-mediated transgene activation in a dose-dependent manner (IC50 approximately 30 nM). These data demonstrate that TLR4 is involved in lipopolysaccharide signaling and serves as a cell-surface co-receptor for CD14, leading to lipopolysaccharide-mediated NF-kappaB activation and subsequent cellular events.

Leptin signaling in the hypothalamus of normal rats in vivo

Leptin has been shown to activate multiple signaling molecules in cultured cells, including Janus kinase-2, STAT (signal transducer and activator of transcription) proteins, and mitogen-activated protein kinase, and to stimulate the DNA-binding activity of STAT3 in mouse hypothalamus. In this study, the activation of candidate leptin signaling molecules in the hypothalamus of normal rats in vivo was investigated. Fasted male Sprague-Dawley rats were injected iv with recombinant murine leptin or vehicle. Plasma leptin concentrations were determined at defined time points, and the phosphorylation of signaling proteins was assessed in hypothalamic lysates. There was a marked increase in plasma leptin concentration at 2 min and a gradual decline by 45 min after leptin injection. Immunoblotting analysis of hypothalamic lysates with a phosphospecific STAT3 antibody demonstrated a time-dependent stimulation of STAT3 tyrosine phosphorylation. STAT3 phosphorylation was first evident at 5 min and was maximal at 30 min after leptin injection. By contrast, leptin did not increase the phosphorylation of Janus kinase proteins, mitogen-activated protein kinase, or STAT1 and -5 despite abundant expression of these signaling molecules in the hypothalamus. These results differ from findings in cultured cells and in vitro systems. It remains unclear how signaling is propagated downstream from the leptin receptor to STAT3, but this may involve novel signaling intermediates.

Stabilization and localization of Xist RNA are controlled by separate mechanisms and are not sufficient for X inactivation

These studies address whether XIST RNA is properly localized to the X chromosome in somatic cells where human XIST expression is reactivated, but fails to result in X inactivation (Tinker, A.V., and C.J. Brown. 1998. Nucl. Acids Res. 26:2935-2940). Despite a nuclear RNA accumulation of normal abundance and stability, XIST RNA does not localize in reactivants or in naturally inactive human X chromosomes in mouse/ human hybrid cells. The XIST transcripts are fully stabilized despite their inability to localize, and hence XIST RNA localization can be uncoupled from stabilization, indicating that these are separate steps controlled by distinct mechanisms. Mouse Xist RNA tightly localized to an active X chromosome, demonstrating for the first time that the active X chromosome in somatic cells is competent to associate with Xist RNA. These results imply that species-specific factors, present even in mature, somatic cells that do not normally express Xist, are necessary for localization. When Xist RNA is properly localized to an active mouse X chromosome, X inactivation does not result. Therefore, there is not a strict correlation between Xist localization and chromatin inactivation. Moreover, expression, stabilization, and localization of Xist RNA are not sufficient for X inactivation. We hypothesize that chromosomal association of XIST RNA may initiate subsequent developmental events required to enact transcriptional silencing.

Intestinal adaptation after extensive small bowel resection: differential changes in growth and insulin-like growth factor system messenger ribonucleic acids in jejunum and ileum

The distal small bowel exhibits greater adaptive growth than proximal segments after partial small intestine resection. To explore this process, we evaluated adaptive cellularity, intestinal insulin-like growth factor (IGF) system messenger RNA (mRNA) transcripts, and effects of recombinant IGF-I treatment in jejunum and ileum of adult rats. Gastrostomy-fed animals underwent 80% jejuno-ileal resection or intestinal transection and reanastomosis without resection, followed by infusion of human recombinant IGF-I (2.4 mg/kgXday) or vehicle. After 7 days, resected rats demonstrated modest adaptive growth in jejunum and marked cell proliferation in ileum. Resection increased IGF-I mRNA in both jejunum (183%) and ileum (249%) and up-regulated IGFBP-4 mRNA levels in both tissues. IGFBP-3 mRNA fell significantly in ileum after resection. IGF-I infusion modestly increased ileal cellularity after resection, but had no effect in jejunum. IGF-I markedly increased IGFBP-3 mRNA levels in jejunum after both transection and resection. These data confirm that bowel resection induces greater adaptive growth in ileum than jejunum. IGF-I administration modestly increases ileal, but not jejunal, growth after resection. Increased levels of intestinal IGF-I and IGFBP-4 mRNA suggest roles for IGF-I and IGFBP-4 in mediating small bowel adaptation. Higher levels of jejunal IGFBP-3 mRNA may be related to limited jejunal vs. ileal growth after extensive jejuno-ileal resection.

Particulate emission rates for unpaved shoulders along a paved road

This paper reports the first empirical estimate of particle emissions from unpaved shoulders along paved roads. Its objectives are to develop and demonstrate an emission rate measurement methodology that can be applied in different areas; identify the mechanisms that suspend dust from unpaved shoulders and the observables related to this suspension process; and quantify PM10 mass emissions in the form of an emission rate. To achieve these objectives, fast-response observations from nephelometers and a sonic anemometer were used to characterize short-lived dust plumes generated by passing vehicles. In addition, detailed soil surface measurements determined the mechanical properties of the shoulder surfaces. Large traffic-induced turbulence events that led to significant dust entrainment were almost exclusively caused by "large" vehicles such as trucks, semis, and vehicles pulling trailers, all traveling 50-65 mph. PM10 emission rates for these large, fast-traveling vehicles were determined to be 8 +/- 4 grams per vehicle kilometer traveled under dry conditions. Emissions due to smaller vehicles such as cars, vans, and sport utility vehicles were negligible for normal on-road driving. These results indicate that the majority of PM10 emissions from unpaved shoulders is caused by relatively few vehicles.

Effects of dietary protein and tumor necrosis factor on components of the insulin-like growth factor-I pathway in the colon and small intestine in protein-depleted rats

Intestinal cell growth is markedly affected by nutrient intake and the presence of cytokines. Since insulin-like growth factor-I (IGF-I) is an important hormone regulator of intestinal proliferation, this study examined the effects of dietary protein content and tumor necrosis factor (TNF) on mRNA levels of IGF-I, IGF-I receptor, IGF binding protein-3 (IGFBP-3), and IGFBP-4 and on the histology of the colon, jejunum, and ileum in protein-malnourished rats. After 2 weeks of feeding a 2% casein diet, rats continued on the 2% casein diet or were refed with a 20% casein diet and received daily intraperitoneal injections of either TNF (50 microg/kg) or saline for 4 days. The abundance of mRNA in the intestine was determined by RNA dot-blot analysis, and morphology measurements were performed by light microscopy. Simultaneous refeeding with the 20% casein diet and administration of TNF led to a modest increase in IGF-I and IGFBP-4 mRNA abundance in the colon. However, in the jejunum and ileum, refeeding had no effect but TNF caused a decrease in IGF-I and IGFBP-3 mRNA levels in malnourished rats. Refeeding with the 20% casein diet resulted in relatively modest histologic changes, which were greater in the colon versus the small intestine. The decreased magnitude of histologic changes in the order of the colon, ileum, and jejunum may reflect a response to a gradient of amino acid availability from intraluminal nutrients. These data demonstrate that TNF has distinct effects on colon and small intestine mRNA, but these mild changes had only a slight impact in the colon and did not translate into identifiable histologic changes in the small intestine. Combined protein restriction and TNF administration had only a modest effect on intestinal mRNA levels and mucosal histology.

Insulin-like growth factor-I receptor internalization regulates signaling via the Shc/mitogen-activated protein kinase pathway, but not the insulin receptor substrate-1 pathway

Insulin-like growth factor-I (IGF-I) receptors activate divergent signaling pathways by phosphorylating multiple cellular proteins, including insulin receptor substrate-1 (IRS-1) and the Shc proteins. Following hormone binding, IGF-I receptors cluster into clathrin-coated pits and are internalized via an endocytotic mechanism. This study investigates the relationship between IGF-I receptor internalization and signaling via IRS-1 and Shc. A mutation in the C terminus of the IGF-I receptor decreased both the rate of receptor internalization and IGF-I-stimulated Shc phosphorylation by more than 50%, but did not affect IRS-1 phosphorylation. Low temperature (15 degrees C) decreased IGF-I receptor internalization and completely inhibited Shc phosphorylation. Although receptor and IRS-1 phosphorylation were decreased in accordance with delayed binding kinetics at 15 degrees C, the ratio of IRS-1 to receptor phosphorylation was increased more than 2-fold. Dansylcadaverine decreased receptor internalization and Shc phosphorylation, but did not change receptor or IRS-1 phosphorylation. Consistent with these findings, dansylcadaverine inhibited IGF-I-stimulated Shc-Grb2 association, mitogen-activated protein kinase phosphorylation, and p90 ribosomal S6 kinase activation, but did not affect the association of phosphatidylinositide 3-kinase with IRS-1 or activation of p70 S6 kinase. These data support the concept that Shc/mitogen-activated protein kinase pathway activation requires IGF-I receptor internalization, whereas the IRS-1 pathway is activated by both cell surface and endosomal receptors.

Tissue-specific effects of chronic dietary protein restriction and gastrostomy on the insulin-like growth factor-I pathway in the liver and colon of adult rats

Dietary protein restriction decreases plasma concentrations of insulin-like growth factor-I (IGF-I) and reduces IGF-I mRNA levels in the liver. In addition to the actions of systemic IGF-I, locally produced IGF-I is thought to mediate autocrine and paracrine growth effects in the colon. The objectives of the present study were to investigate the IGF-I pathway in the colon and liver of adult rats under conditions of dietary protein restriction, surgical stress, and dietary protein repletion. Two groups of rats were placed on either a 20% or 2% casein diet for 19 days. Two additional groups of rats underwent gastrostomy after a 2% casein diet for 2 weeks, and then were either kept on the 2% casein diet or changed to a 20% casein diet until day 19. Dietary protein restriction reduced plasma concentrations of IGF-I and IGF-binding proteins (IGFBPs) and hepatic IGF-I mRNA content, while increasing colonic IGF-I receptor mRNA. Gastrostomy in protein-depleted animals had no effect on hepatic IGF-I mRNA, but led to a marked increase in colonic IGF-I mRNA levels. Dietary protein repletion resulted in a decrease in colonic IGF-I receptor mRNA. The distinct effects of dietary protein depletion and operative stress on the IGF pathway in the colon as compared with the liver may serve to maintain the level of IGF-I signaling in the colon by autocrine or paracrine mechanisms under these conditions.

The adapter protein Grb10 associates preferentially with the insulin receptor as compared with the IGF-I receptor in mouse fibroblasts

To identify receptor-associated proteins that may contribute to the specificity of insulin and IGF-I signaling responses, a mouse embryo library was screened using the yeast two-hybrid system. Multiple receptor-interactive clones encoding the SH2 domain of the adapter protein Grb10 were isolated. Subsequent cloning of the full-length Grb10 sequence from a mouse fat cDNA library defined a previously unknown Grb10 variant, that appears to be the predominant isoform in mouse tissues. Receptor-deficient R- cells (fibroblasts from mice with homologous disruption of the IGF-I receptor gene) and transfected R- cells expressing either insulin receptors (R-IR cells) or IGF-I receptors (R+ cells) were used to investigate the specificity of Grb10 interaction with the two related receptors. Hormone-activated insulin receptors in R-IR cells coprecipitated with three species, all recognized as Grb10 isoforms by specific Grb10 antibody. Under the same conditions, Grb10 was essentially undetectable in IGF-I receptor immunoprecipitates from stimulated R+ cells. Grb10 association with insulin receptors was maximal at 10 nM insulin stimulation and sustained from 5-10 min after hormone stimulation in R-IR cells. In conclusion, Grb10 interacts preferentially with insulin vs. IGF-I receptors in intact cells and, thus, may have a role in mediating insulin receptor-specific cellular responses.

The use of routine wrist radiography in the evaluation of patients with carpal tunnel syndrome

The objective of this study was to evaluate the use of routine wrist radiography in the evaluation of patients with carpal tunnel syndrome (CTS). In the setting of a community-based hand surgery practice, we performed a retrospective review of charts and radiographs for 300 consecutive patients (447 wrists) meeting clinical and electrophysiologic criteria for CTS. Data on all patients included information obtained by the use of medical history questionnaires, physical examinations, nerve conduction studies, and radiographs of the wrist. Abnormalities were noted in 146 of 447 wrist radiographs (33%). Eighty-three (18.6%) had abnormalities that might have been implicated in the development of CTS, although these findings would not alter management. For only 2 of 447 wrists (0.4% of wrists; 0.6% of patients) were there radiographic findings of therapeutic significance. Radiographic charges were calculated to be $5,869 to $20,115 for each finding of therapeutic significance. We conclude that wrist radiographs should not be performed routinely in patients with CTS, owing to the low yield of useful information.

Gut adaptation and the insulin-like growth factor system: regulation by glutamine and IGF-I administration

Intestinal adaptation after extensive small bowel resection in rats is augmented by the provision of diets supplemented with the amino acid glutamine (Gln) or by administration of insulin-like growth factor-I (IGF-I). The goal of this study was to investigate potential synergistic effects of Gln and IGF-I on postresection ileal hyperplasia. Rats underwent 80% small bowel resection (SBR) and then were fed low-Gln or L-Gln-enriched diets and subcutaneously given recombinant human IGF-I or vehicle for 7 days. Gln and IGF-I each significantly enhanced adaptive ileal hyperplasia (DNA content) compared with rats receiving vehicle and low-Gln diet. Ileal DNA content was highest when IGF-I was administered together with Gln supplementation. Combined IGF-I plus Gln synergistically increased ileal weight and protein content. This was associated with higher plasma concentrations of IGF-I and Gln than observed when IGF-I or Gln was given individually. Ileal IGF-I mRNA expression rose nearly twofold during gut adaptation after SBR; this response was augmented with IGF-I administration but was unaltered by Gln feeding. In contrast, dietary Gln, but not IGF-I therapy, prevented a decrease in hepatic IGF-I mRNA induced by SBR. We conclude that parenteral IGF-I and enteral Gln have both individual and synergistic effects on ileal adaptation after massive small intestinal resection. These findings support the concept that specific gut-trophic nutrients and growth factors may be combined to enhance intestinal adaptation and possibly reduce the severity of short bowel syndrome after intestinal resection.