Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

Effectiveness of decision support tools on reducing antibiotic use for respiratory tract infections: a systematic review and meta-analysis

Background: Clinical decision support tools (CDSs) have been demonstrated to enhance the accuracy of antibiotic prescribing among physicians. However, their effectiveness in reducing inappropriate antibiotic use for respiratory tract infections (RTI) is controversial. Methods: A literature search in 3 international databases (Medline, Web of science and Embase) was conducted before 31 May 2023. Relative risk (RR) and corresponding 95% confidence intervals (CI) were pooled to evaluate the effectiveness of intervention. Summary effect sizes were calculated using a random-effects model due to the expected heterogeneity (I 2 over 50%). Results: A total of 11 cluster randomized clinical trials (RCTs) and 5 before-after studies were included in this meta-analysis, involving 900,804 patients met full inclusion criteria. Among these studies, 11 reported positive effects, 1 reported negative results, and 4 reported non-significant findings. Overall, the pooled effect size revealed that CDSs significantly reduced antibiotic use for RTIs (RR = 0.90, 95% CI = 0.85 to 0.95, I 2 = 96.10%). Subgroup analysis indicated that the intervention duration may serve as a potential source of heterogeneity. Studies with interventions duration more than 2 years were found to have non-significant effects (RR = 1.00, 95% CI = 0.96 to 1.04, I 2 = 0.00%). Egger's test results indicated no evidence of potential publication bias (p = 0.287). Conclusion: This study suggests that CDSs effectively reduce inappropriate antibiotic use for RTIs among physicians. However, subgroup analysis revealed that interventions lasting more than 2 years did not yield significant effects. These findings highlight the importance of considering intervention duration when implementing CDSs. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023432584, Identifier: PROSPERO (CRD42023432584).

A binary pulsar in a 53-minute orbit

Spider pulsars are neutron stars that have a companion star in a close orbit. The companion star sheds material to the neutron star, spinning it up to millisecond rotation periods, while the orbit shortens to hours. The companion is eventually ablated and destroyed by the pulsar wind and radiation1,2. Spider pulsars are key for studying the evolutionary link between accreting X-ray pulsars and isolated millisecond pulsars, pulsar irradiation effects and the birth of massive neutron stars3-6. Black widow pulsars in extremely compact orbits (as short as 62 minutes7) have companions with masses much smaller than 0.1 M⊙. They may have evolved from redback pulsars with companion masses of about 0.1-0.4 M⊙ and orbital periods of less than 1 day8. If this is true, then there should be a population of millisecond pulsars with moderate-mass companions and very short orbital periods9, but, hitherto, no such system was known. Here we report radio observations of the binary millisecond pulsar PSR J1953+1844 (M71E) that show it to have an orbital period of 53.3 minutes and a companion with a mass of around 0.07 M⊙. It is a faint X-ray source and located 2.5 arcminutes from the centre of the globular cluster M71.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Evaluation of the impact of the COVID-19 pandemic on health service utilization in China: A study using auto-regressive integrated moving average model

Background

The outbreak of COVID-19 in early 2020 presented a major challenge to the healthcare system in China. This study aimed to quantitatively evaluate the impact of COVID-19 on health services utilization in China in 2020.

Methods

Health service-related data for this study were extracted from the China Health Statistical Yearbook. The Auto-Regressive Integrated Moving Average model (ARIMA) was used to forecast the data for the year 2020 based on trends observed between 2010 and 2019. The differences between the actual 2020 values reported in the statistical yearbook and the forecast values from the ARIMA model were used to assess the impact of COVID-19 on health services utilization.

Results

In 2020, the number of admissions and outpatient visits in China declined by 17.74 and 14.37%, respectively, compared to the ARIMA model’s forecast values. Notably, public hospitals experienced the largest decrease in outpatient visits and admissions, of 18.55 and 19.64%, respectively. Among all departments, the pediatrics department had the greatest decrease in outpatient visits (35.15%). Regarding geographical distribution, Beijing and Heilongjiang were the regions most affected by the decline in outpatient visits (29.96%) and admissions (43.20%) respectively.

Conclusion

The study’s findings suggest that during the first year of the COVID-19 pandemic, one in seven outpatient services and one in six admissions were affected in China. Therefore, there is an urgent need to establish a green channel for seeking medical treatment without spatial and institutional barriers during epidemic prevention and control periods.

Traditional Chinese Medicine constitution types of high-normal blood pressure: A meta-analysis

Objective

We determined the distribution of constitutional types of high-normal blood pressure in Traditional Chinese Medicine (TCM) and provided evidence for the prevention of high-normal blood pressure and hypertension.

Methods

Eight digital databases were searched from January 2011 to November 2022, including PubMed, EMBASE, Web of Science, EBSCOhost, CNKI, CBM, Wangfang, and CQVIP. We performed a meta-analysis with the random-effects model or fixed-effects model to describe the distribution of constitutional types of high-normal blood pressure in TCM. The studies were assessed based on heterogeneity testing and the potential for publication bias. The meta-analysis was performed on Stata software 15.0.

Results

A total of 17 studies with 8118 participants were included in this meta-analysis. The proportion of the biased constitution (82.3%; 95% CI: 75.6%-89.1%, p < 0.001) was higher than the balanced constitution (17.3%; 95% CI: 10.7-23.8%, p < 0.001). Phlegm-dampness constitution, Yin-deficiency constitution, and damp-heat constitution accounted for 16.0% (95%CI: 10.5-21.5%, p < 0.001), 14.8% (95% CI: 11.0-18.6%, p < 0.001), 11.3% (95% CI: 8.0-14.5%, p < 0.001) of the total high-normal blood pressure cases, respectively. The subgroup analyses performed that region, age and gender were positively associated with the distribution of constitution types of high-normal blood pressure in TCM. Compared with the general population, the risk of high-normal blood pressure in people with the phlegm-dampness constitution, Yin-deficiency constitution, and blood-stasis constitution was 2.665 (95%CI: 2.286-3.106, p < 0.001), 2.378 (95%CI: 1.197-4.724, p = 0.013), 1.965 (95%CI: 1.634-2.363, p < 0.001) times of the general population, respectively. Meanwhile, the risk of high-normal blood pressure was lower in people with a balanced constitution (0.248, 95%CI: 0.165-0.372, p < 0.001).

Conclusions

Phlegm-dampness constitution, Yin-deficiency constitution, and damp-heat constitution were the common constitution types of high-normal blood pressure. There might also be differences in the distribution characteristics of TCM constitution among people with high-normal blood pressure in different regions, ages, and genders. Finally, a balanced constitution might be a protective factor for hypertensive people.

Substantial Increase in Accessibility to Essential Anticancer Medicines in Anhui, China: A Longitudinal Study

The study aimed to evaluate the change in accessibility of essential anticancer medicines, from 2015 to 2018 in a pilot province for health care reform in China. Data on access to 23 essential anticancer medicines was obtained from 6 provincial tertiary hospitals. A comprehensive analysis was applied to explore these trends. The total utilization of anticancer medicines had increased by an average of 2.57 times (P < .001) during the study period, of which targeted anticancer medicines had the fastest growth rate of 6.45 times (P < .001). The prices of all targeted medicines and original brands (OBs) were showing a downward trend, with the average change rate of -32% and -28% respectively (both P < .001). In contrast, the price of non-targeted medicines and lowest-price generics (LPG) increased by an average of 98% (P < .001) and 117% (P < .004) respectively. All targeted anticancer medicines were found to be unaffordable under this standard of this study, but the affordability of these medicines is on the rise. The study suggested positive changes in the utilization, price, and affordability of the most essential anticancer medicines. In the future, comprehensive strategies need to be conducted to further increase the affordability of targeted anticancer medicines.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Causal association between rheumatoid arthritis and celiac disease: A bidirectional two-sample mendelian randomization study

Objectives: Rheumatoid Arthritis (RA) has been associated with Celiac Disease (CD) in previous observational epidemiological studies. However, evidence for this association is limited and inconsistent, and it remains uncertain whether the association is causal or due to confounding or reverse causality. This study aimed to assess the bidirectional causal relationship between RA and CD. Methods: In this two-sample Mendelian randomization (MR) study, instrumental variables (IVs) for RA were derived from a genome-wide association studies (GWAS) meta-analysis including 58,284 subjects. Summary statistics for CD originated from a GWAS meta-analysis with 15,283 subjects. The inverse-variance weighted (IVW) method was used as the primary analysis. Four complementary methods were applied, including the weighted-median, weighted mode, MR pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression, to strengthen the effect estimates. Results: Positive causal effects of genetically increased RA risk on CD were derived [IVW odds ratio (OR): 1.46, 95% confidence interval (CI): 1.19-1.79, p = 3.21E-04]. The results of reverse MR analysis demonstrated no significant causal effect of CD on RA (IVW OR: 1.05, 95% CI: 0.91-1.21, p = 0.499). According to the sensitivity analysis, horizontal pleiotropy was unlikely to distort the causal estimates. Conclusion: This study reveals a causality of RA on CD but not CD on RA among patients of European descent. This outcome suggests that the features and indicators of CD should regularly be assessed for RA patients.

Diet-related knowledge, attitudes, and behaviors among young and middle-aged individuals with high-normal blood pressure: A cross-sectional study in China

Background

Dietary modifications play an important role in the prevention and management of high-normal blood pressure (BP). The aim of this study was to investigate diet-related knowledge, attitudes, and behaviors, and the socio-demographic determinants of these, among young and middle-aged Chinese individuals with high-normal BP.

Methods

Data from the 2015 China Health and Nutrition Survey (CHNS) were analyzed in this study. A total of 1,756 subjects with high-normal BP were included. A chi-square test and binary logistic regression analysis were conducted to identify the risk factors toward diet-related knowledge, attitudes, and behaviors.

Results

A total of 37.4% of the participants knew about the Chinese Food Pagoda (CFP) or the Dietary Guidelines for Chinese Residents (DGCR). Overall, 39.8% of the subjects were classified as having adequate diet-related knowledge literacy, 27.8% reported positive diet-related attitudes to healthy eating, and 35.3% reportedly looked for nutrition knowledge. Of note, 72.4% and 80.1% of the participants reported liking to eat fruits and vegetables, respectively. Individuals with a middle school education [odds ratio (OR) = 1.784, 95% CI = 1.236-2.576], high school/vocational education (OR = 1.944, 95% CI = 1.305-2.896), and college degree or above (OR = 2.089, 95% CI = 1.341-3.322), who were living in a rural area (OR = 1.311, 95% CI = 1.048-1.639), proactively looking for nutrition knowledge (OR = 1.529, 95% CI = 1.227-1.906), and reported liking to eat vegetables (OR = 1.939, 95% CI = 1.409-2.688), were more likely to have sufficient dietary knowledge literacy. Managers (OR = 1.655, 95% CI = 1.039-2.635) were more likely to have positive dietary attitudes. Female gender (OR = 1.396, 95% CI = 1.089-1.790), high school/vocational school education (OR = 2.071, 95% CI = 1.269-3.379), college degree and above (OR = 2.207, 95% CI = 1.262-3.862), knowledge about the CFP or DGCR (OR = 8.138, 95% CI = 6.326-10.468), and sufficient dietary knowledge literacy (OR = 1.338, 95% CI = 1.050-1.705) were associated with an increased likelihood of looking for nutrition knowledge.

Conclusion

Individuals with high-normal BP, predominantly males, living in rural area, with lower education, farmers, workers, service workers, and workers in the non-government employment unit may have poor diet-related knowledge, attitudes, and behaviors.

Determining the association between different living arrangements and depressive symptoms among over-65-year-old people: The moderating role of outdoor activities

Background

China is presently facing the challenge of meeting enormous health demands because of its rapidly aging society. Enrolling older persons in eldercare institutions is a helpful alternative for relieving family caregivers and promoting healthy aging. However, changes in the living environment may negatively affect the mental health of the elderly.

Objective

To explore the association between different living arrangements and depressive symptoms among over-65-year-old people in China and the moderating role of outdoor activities.

Method

The 2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) used a mixed sampling method to collect the health and demographic information of 15,874 older adults over 65 years from 23 provinces in China. After considering this study's inclusion and exclusion criteria, the final sample comprised 12,200 participants. The participants' risk of depressive symptoms was assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10). The potential association between the two elements was tested using a regression model.

Result

This study's findings suggested a significant relationship between depressive symptoms and living arrangements (P < 0.001). Participants living alone and those living in eldercare institutions had 1.26-times (95%CI: 1.10–1.44) and 1.39-times (95%CI: 1.09–1.77) higher risks of depressive symptoms, respectively, than those living with household members. Outdoor activities play a moderating role between different living arrangements and depressive symptoms. Among participants who engaged in outdoor activities, no significant difference was observed in the risk of depressive symptoms between those living in eldercare institutions and those living with household members (adjusted odds ratio = 1.15, 95%CI = 0.81–1.64, P = 0.426).

Conclusion

The high risk of depressive symptoms among older Chinese people living alone or in eldercare institutions requires considerable attention. The evidence from this study suggests that older people living alone and those living in eldercare institutions should regularly engage in appropriate outdoor activities.

[Gender differences of genetic etiology in the incidence of major depressive disorder among Han freshmen]

Objective: To analyze the gender differences of genetic etiology in the incidence of major depression disorder among Han freshmen. Methods: A 1-year follow-up survey was carried out among 8 079 Han freshmen from Jining, Rizhao and Weifang without lifetime major depressive disorder (MDD) at baseline (April to October 2018) and 4 828 venous blood samples were also collected. After extracting DNA, Sequenom Mass Array time-of-flight mass spectrometry biochip technology was used to detect the genotypes of 17 single nucleotide polymorphisms (SNPs) MDD-related loci. Logistic regression was used for univariate analysis. Generalized multifactor dimension reduction was used to analyze gene-gene interactions. Composite International Diagnostic Interview (CIDI) 3.0 was used for MDD diagnosis. Results: The 1-year incidence of MDD among Han freshmen was 2.23% (95%CI: 1.91%-2.60%) and the gender difference of incidence between males (1.97%, 95%CI: 1.52%-2.56%) and females (2.39%, 95%CI: 1.98%-2.90%) was not statistically significant (P>0.05). AG genotype of rs768705 (nearby gene: TMEM161B) was a risk factor for MDD (OR=1.98, 95%CI: 1.24-2.83). The TC genotype of rs17727765 (nearby gene: CRYBA1) was only a risk factor for MDD in males (OR=9.61, 95%CI: 2.04-45.30). An 8-loci interaction model (PMFBP1, OLFM4, LHPP, ENOX1, TMEM161B, SPPL3, FBXL4 and L3MBTL2) could predict MDD in women with an accuracy rate of 60.05%. No effective prediction model was found for MDD in men. Conclusions: There might be gender differences in the genetic etiology of MDD. Further researches on the genetic causes of MDD in men should be explored.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

Knowledge, Attitude, and Prescription Practice on Antimicrobials Use Among Physicians: A Cross-Sectional Study in Eastern China

Over-prescription of antimicrobials for patients is a major driver of bacterial resistance. The aim of the present study was to assess the knowledge, attitude, and prescription practices regarding antimicrobials among physicians in the Zhejiang province in China, and identify the determining factors. A total of 600 physicians in public county hospitals and township health institutions were surveyed cross-sectionally using a structured electronic questionnaire. The questionnaire was completed by 580 physicians and the response rate was 96.67%. The mean score of 11 terms related to antimicrobial knowledge was 6.81, and an average of 32.1% of patients with upper respiratory tract infections (URTIs) were prescribed antimicrobials. Multivariate analysis indicated that young general practitioners with less training are more likely to contribute to more frequent antimicrobial prescriptions ( P < .05). In contrast, older physicians with more training are more willing to provide patients with the correct knowledge regarding antimicrobials and less likely to prescribe antimicrobials for URTIs. Correlation analysis showed that the level of physician's knowledge, attitude, and prescription practice is related ( P < .05). In conclusion, proper prescription of antimicrobials depends on adequate knowledge and regular training programs for physicians.

No pulsed radio emission during a bursting phase of a Galactic magnetar

Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

Prices, availability, and affordability of national essential medicines in public primary hospitals: A cross-sectional survey in poverty-stricken rural areas in China

INTRODUCTION

This study aimed to determine the prices, availability, and affordability of national essential medicines in public primary hospitals in poverty-stricken areas of Anhui province, China.

METHODS

A cross-sectional study was conducted in 143 public primary hospitals in Anhui province, eastern China. Data on access to 44 essential medicines was evaluated using the standardized methodology available in the World Health Organization and Health Action International manual.

RESULTS

Median price rates show that 46.51% (21 of 44) of the lowest price generics and 100% of the originator brands were more expensive than the international reference price. The median availability of the 44 medicines was 31.47%, and 65.91% (29 of 44) of the medicines had less than 50% availability. The majority of the medicines were affordable as they would cost less than a day's income in sample areas. Suppliers could respond to 88.27% of the procuring orders raised by the 143 hospitals in the study, but this ranged from 43.96% to 99.86%.

CONCLUSIONS

There is poor availability and non-ideal response rate of medicine delivery in public primary hospitals in poverty-stricken areas in eastern China. Further implementation of national essential medicine policy needs to focus on improving both availability and distribution efficiency in these areas.

P2248Impact of Lipoprotein (a) levels on the presence and severity of coronary artery disease in female patients: a large cross-sectional Chinese cohort study

Background

Lipoprotein (a) [Lp(a)] is recently recognized as a risk factor of atherosclerosis, and the development of coronary artery disease (CAD) in women is not fully understood.

Purpose

The present study aimed to examine the association of Lp(a) levels with the presence and severity of (CAD) in female patients pre- and post-menopause.

Methods

A total of 3712 female patients who received coronary angiography were consecutively enrolled. The level of Lp(a) was measured and compared among patients with and without CAD or myocardial infarction (MI), pre- or post- menopause. The association of Lp(a) with the presence of CAD and the severity of coronary atherosclerosis assessed by Gensini Score were examined.

Results

The average of Lp(a) levels were elevated as age increased in female subjects. Notably, women after menopause had higher Lp(a) levels compared with that before menopause [16.8 mg/dL (IQR 7.54–41.12 mg/dL) vs. 14.7 mg/dL (IQR 6.72–30.82 mg/dL), p=0.002]. Furthermore, multiple logistic regression analysis identified that Lp(a) >30mg/dL was an independent risk factor of CAD in the postmenopausal female (OR1.38, 95% CI 1.13–1.69, p=0.002). Finally, Lp(a) had a positive correlation with Gensini score (r=0.11, p<0.001), and Lp(a) >30mg/dL was an independent risk factor for high Gensini score (OR 1.43, 95% CI 1.14–1.79, p<0.001). While such results were not observed in the premenopausal females.

Baseline characteristics of all patients Before menopause (n=525) Post menopause (n=3187) P value Age, (years) 46 (42–49) 62 (58–68) <0.001* Hypertension, n (%) 231 (44.00) 2097 (65.80) <0.001* Diabetes mellitus, n (%) 68 (12.95) 849 (26.64) <0.001* LDL-C (mmol/L) 2.73±1.05 2.77±0.99 0.366 Lp(a) (mg/dL) 14.7 (6.72–30.82) 16.8 (7.54–41.12) 0.002* Data are expressed as mean ± SD or median (interquartile range) and numbers (percentages). BMI, body mass index; TC, total cholesterol; TG, triglyceride; LDL-C, low density lipoprotein cholesterol; HDL-C, high density lipoprotein cholesterol; Lp(a), lipoprotein(a); HsCRP, high-sensitivity C-reactive protein. *Statistically significant differences exist between two groups. CAD, coronary artery disease.

Lp(a) in pre- and post-menopausal women

Conclusion

The present study indicated that circulating Lp(a) levels were independently associated with the presence and severity of CAD in the postmenopausal female, suggesting that further study may be needed to examine the role of Lp(a) in the development of CAD in female individuals with different menopausal status.

Self-Medication with Antibiotics among University Students in LMIC: A systematic review and meta-analysis

INTRODUCTION

Self-medication with antibiotics (SMA) is common among university students in low and middle-income countries (LMICs). However, there has been no meta-analysis and systematic review in the population.

METHODOLOGY

A literature search was conducted using PubMed, Embase and Web of Science for the period from January 2000 to July 2018. Only observational studies that had SMA among university students from LMICs were included. A random-effects model was applied to calculate the pooled effect size with 95% confidence interval (CI) due to the expected heterogeneity (I2 over 50%).

RESULTS

The pooled prevalence of SMA of overall included studies was 46.0% (95% CI: 40.3% to 51.8%). Africa had the highest pooled prevalence of SMA among university students (55.30%), whereas South America had the lowest prevalence (38.3%). Among individual LMICs, the prevalence of SMA among university students varied from as low as 11.1% in Brazil to 90.7% in Congo.

CONCLUSIONS

The practice of SMA is a widespread phenomenon among university students in LMICs and is frequently associated with inappropriate use. Effective interventions such as medication education and stricter governmental regulation concerning antibiotic use and sale are required to be established in order to deal with SMA properly.

Interventions to improve medication adherence among Chinese patients with hypertension: a systematic review and meta-analysis of randomized controlled trails

OBJECTIVE

A systematic review and meta-analysis of randomized controlled trials (RCTs) were performed to understand the effectiveness of medication adherence (MA) interventions among Chinese patients with hypertension.

METHODS

A literature search was conducted with three English databases (PubMed, Web of Science and Embase) and three Chinese databases (China National Knowledge Infrastructure, Wanfang and VIP Database for Chinese Technical Periodicals) for the period from 1970 to October 2017. Only both RCTs with a minimum of 10 participants in each intervention group and Chinese patients with hypertension as participants were included. A random-effects model was applied to calculate pooled effect sizes with 95% CI. Subgroup analysis was conducted to identify potential sources of heterogeneity from duration of intervention, type of intervener, methods of intervention and sites of intervention. Funnel plots and Egger's test were used to evaluate for publication bias.

KEY FINDINGS

A total of 48 studies met criteria for the meta-analysis, including 14 568 participants, testing 57 independent comparisons. Overall, the effect size revealed that interventions significantly improved MA (pooled relative risk = 1.59, 95% CI: 1.43 to 1.78; pooled Cohen's d = 1.42, 95% CI: 0.976 to 1.876). Interventions were found to significantly reduce blood pressure (BP) (systolic BP: Cohen's d = -0.85, 95% CI: -1.11 to -0.60 and diastolic BP: Cohen's d = -0.73, 95% CI: -1.00 to -0.46). Longer duration of intervention gave better effectiveness. Physician as interventionist, regular follow-up visits and interventions conducted at a hospital were associated with better effectiveness.

CONCLUSION

Adherence interventions improve MA and reduce uncontrolled BP among Chinese patients with hypertension. In the future, investigators should adopt a skill set to address the problem of poor MA.

Purinergic P2X7 receptor mediates acetaldehyde-induced hepatic stellate cells activation via PKC-dependent GSK3β pathway

The activation of hepatic stellate cells (HSCs) is an essential part in the development of alcoholic liver fibrosis (ALF). In this study, stimulated HSCs with 200μM acetaldehyde for 48h was used to imitate alcoholic liver fibrosis in vitro. The western blot and qRT-PCR results showed that P2X7R expression was significantly increased in the activation of HSCs after acetaldehyde treatment. Interestingly, activation of P2X7R by stimulating with P2X7R agonist BzATP significantly promoted acetaldehyde-induced CyclinD1 expression, cell proportion in S phase, inflammatory response, and the protein and mRNA levels of α-SMA, collagen I. In contrast, blockage of P2X7R by stimulating with the inhibitor A438079 or transfecting with specific siRNA dramatically suppressed acetaldehyde-induced HSCs activation. Furthermore, PKC activation treated with PMA could obviously up-regulate the expression of α-SMA and collagen I and the phosphorylation of GSK3β, while inhibition of PKC significantly reduced GSK3β activation. Moreover, GSK3β inhibition harvested a dramatic decrease of the mRNA and protein levels of α-SMA and collagen I by suppressing GSK3β phosphorylation. Taken together, these results suggested that purinergic P2X7R mediated acetaldehyde-induced activation of HSCs via PKC-dependent GSK3β pathway, which maybe a novel target for limiting HSCs activation.

[Microsurgical management of petroclival meningiomas combined trans-subtemporal and suboccipital retrosigmoid keyhole approach]

OBJECTIVE

With the development of modern skull base minimally invasive technology mature and neural radio surgery techniques, it is necessary to re-examine the therapeutic strategy for the treatment of petroclival meningiomas. To sum up the operative experience and methods in microsurgical resection of petroclival meningiomas by the combining trans-subtemporal and suboccipital retrosigmoid keyhole approach. To explore the minimally invasive operation approach of petroclival meningiomas, to raise the removal degree and to improve the postoperative result using this approach.

METHODS

The clinical data of the consecutive 21 patients with the petroclival meningiomas were reviewed retrospectively. The method, degree of tumor resection,techniques of the combining keyhole approach, Karnofsky performance score (KPS) before and after operation were also analyzed. The neuronavigation guided operation was performed in 9 cases, and 12 cases were operated in the neuroelectrophysiological monitoring.

RESULTS

Total excision of the tumor resection (Simpson, I-II levels) was conducted in 18 cases (85.7%, 18/21), and 3 patients underwent close resection (Simpson III level, 14.3%, 3/21). Postoperative three-dimensional CT showed good lock bone flap restoration; Postoperative pathology confirmed meningioma. Postoperative cranial nerve dysfunction or new original nerve dysfunction were aggravated in 5 cases (23.8%) , including transient trochlear nerve (3 cases), abducent nerve (1 case), and the motor branch of trigeminal nerve paralysis (1 case). Abducent nerve paralysis (1 case) appeared, with hearing impairment. After the 3-month follow-up, 11 cases had the same KPS aspreoperation, 7 cases improved, and 3 cases not improved. The KPS score was 77.14±23.12 on average, and there was no statistically significant difference compared with that before operation (P>0.05). The postoperative follow-up for half a year showed fluent speaking and writing in 19 cases (KPS 70 or higher), and general recovery in 2 cases (KPS<70). The postoperative follow-up for 3-29 months showed no tumor recurrence or progress.

CONCLUSION

The combining trans-subtemporal and suboccipital retrosigmoid keyhole approach is simple, safe, and minimally invasive, and an ideal operation approach of petroclival meningioma. To master the operation skills and the intraoperative matters needing attention in the operation, is favorable to improve the resection rate and curative effect.

[Microsurgical management of petroclival meningiomas combined trans-subtemporal and suboccipital retrosigmoid keyhole approach]

OBJECTIVE

With the development of modern skull base minimally invasive technology mature and neural radio surgery techniques, it is necessary to re-examine the therapeutic strategy for the treatment of petroclival meningiomas. To sum up the operative experience and methods in microsurgical resection of petroclival meningiomas by the combining trans-subtemporal and suboccipital retrosigmoid keyhole approach. To explore the minimally invasive operation approach of petroclival meningiomas, to raise the removal degree and to improve the postoperative result using this approach.

METHODS

The clinical data of the consecutive 21 patients with the petroclival meningiomas were reviewed retrospectively. The method, degree of tumor resection,techniques of the combining keyhole approach, Karnofsky performance score (KPS) before and after operation were also analyzed. The neuronavigation guided operation was performed in 9 cases, and 12 cases were operated in the neuroelectrophysiological monitoring.

RESULTS

Total excision of the tumor resection (Simpson, I-II levels) was conducted in 18 cases (85.7%, 18/21), and 3 patients underwent close resection (Simpson III level, 14.3%, 3/21). Postoperative three-dimensional CT showed good lock bone flap restoration; Postoperative pathology confirmed meningioma. Postoperative cranial nerve dysfunction or new original nerve dysfunction were aggravated in 5 cases (23.8%) , including transient trochlear nerve (3 cases), abducent nerve (1 case), and the motor branch of trigeminal nerve paralysis (1 case). Abducent nerve paralysis (1 case) appeared, with hearing impairment. After the 3-month follow-up, 11 cases had the same KPS aspreoperation, 7 cases improved, and 3 cases not improved. The KPS score was 77.14±23.12 on average, and there was no statistically significant difference compared with that before operation (P>0.05). The postoperative follow-up for half a year showed fluent speaking and writing in 19 cases (KPS 70 or higher), and general recovery in 2 cases (KPS<70). The postoperative follow-up for 3-29 months showed no tumor recurrence or progress.

CONCLUSION

The combining trans-subtemporal and suboccipital retrosigmoid keyhole approach is simple, safe, and minimally invasive, and an ideal operation approach of petroclival meningioma. To master the operation skills and the intraoperative matters needing attention in the operation, is favorable to improve the resection rate and curative effect.

Red mud (RM)-Induced enhancement of iron plaque formation reduces arsenic and metal accumulation in two wetland plant species

Human activities have resulted in arsenic (As) and heavy metals accumulation in paddy soils in China. Phytoremediation has been suggested as an effective and low-cost method to clean up contaminated soils. A combined soil-sand pot experiment was conducted to investigate the influence of red mud (RM) supply on iron plaque formation and As and heavy metal accumulation in two wetland plant species (Cyperus alternifolius Rottb., Echinodorus amazonicus Rataj), using As and heavy metals polluted paddy soil combined with three rates of RM application (0, 2%, 5%). The results showed that RM supply significantly decreased As and heavy metals accumulation in shoots of the two plants due to the decrease of As and heavy metal availability and the enhancement of the formation of iron plaque on the root surface and in the rhizosphere. Both wetland plants supplied with RM tended to have more Fe plaque, higher As and heavy metals on roots and in their rhizospheres, and were more tolerant of As and heavy metal toxicity. The results suggest that RM-induced enhancement of the formation of iron plaque on the root surface and in the rhizosphere of wetland plants may be significant for remediation of soils contaminated with As and heavy metals.

Relation of resistin to proprotein convertase subtilisin-kexin type 9 levels in coronary artery disease patients with different nutritional status

OBJECTIVE

To investigate the association of resistin with proprotein convertase subtilisin-kexin type 9 (PCSK9) levels, another novel regulator of atherosclerosis, in the condition of coronary artery disease (CAD).

RESEARCH DESIGN AND METHODS

We prospectively enrolled a total of 356 consecutive stable CAD patients who were not treated with lipid-lowering drugs in the present study. The baseline clinical characteristics were collected. Plasma PCSK9 and resistin levels were determined by ELISA. The relationship between plasma PCSK9 and resistin levels was investigated.

RESULTS

Overall, plasma resistin exhibited a positive nonparametric correlation with PCSK9 levels (r = 0.123, p = 0.02). When the patients were classified into groups based on body mass index (BMI), the resistin correlated significantly to the PCSK9 levels in patients with BMI < 25 kg/m(2) (r = 0.162, p = 0.026) but not in patients with BMI ≥ 25 kg/m(2) (r = 0.087, p = 0.205). Multivariate regression analysis corroborated the relation between the PCSK9 and an elevated resistin level in patients with BMI < 25 kg/m(2) independently of traditional parameters including age, sex, BMI, smoking, family history of CAD, systolic blood pressure, glucose, low density lipoprotein cholesterol, white blood cell, neutrophil to lymphocyte ratio, and high-sensitive C-reactive protein.

CONCLUSIONS

Plasma resistin was positively related to PCSK9 levels in CAD patients with normal weight, suggesting that the circulating resistin might represent a link with PCSK9 level variations in CAD progression of normal body weight.

Neuroprotective effects of Bcl-2 overexpression on nerve cells of rats with acute cerebral infarction

We aimed to investigate the influence of lentiviral-mediated Bcl-2 overexpression in cerebral tissues of rats with acute cerebral infarction. Forty-five rats were randomly divided into sham, model, and treatment groups. The sham and model groups were administered a control lentiviral vector via the intracranial arteries 10 days before surgery, while the treatment group received lentivirus encoding a Bcl-2 overexpression vector. We induced cerebral artery infarction using a suture-occlusion method and analyzed the cerebral expression levels of apoptosis-related genes (caspase-3, Bax), total cerebral apoptosis, range of cerebral tissue infarction, and changes in nerve cell function after 72 h. The Bcl-2-encoding lentivirus was well expressed in rat cerebral tissues. The treatment group had significantly higher expression levels of Bcl-2 than the other two groups. After cerebral infarction, the model group had significantly increased expression levels of caspase-3 and Bax protein in cerebral tissues than the sham (P < 0.05). Expression of these apoptosis-related proteins in the treatment group was obviously lower than that in the model group (P < 0.05), but significantly higher than in the sham group (P < 0.05). Compared to sham, neuronal apoptosis levels and infarction range of cerebral tissues was increased in the model and treatment groups; however, these values in the treatment group were significantly lower than that in the model group (P < 0.05). Importantly, the treatment group had significantly decreased neurological impairment scores (P < 0.05). In conclusion, Bcl-2 over-expression can decrease neuronal apoptosis in rat cerebral tissue, and thus is neuroprotective after cerebral ischemia.

Effects of transcranial direct current stimulation on hemichannel pannexin-1 and neural plasticity in rat model of cerebral infarction

The aim of this study was to investigate the effects of transcranial direct current stimulation (TDCS) on hemichannel pannexin-1 (PX1) in cortical neurons and neural plasticity, and explore the optimal time window of TDCS therapy after stroke. Adult male Sprague-Dawley rats (n=90) were randomly assigned to sham operation, middle cerebral artery occlusion (MCAO), and TDCS groups, and underwent sham operation, unilateral middle cerebral artery (MCA) electrocoagulation, and unilateral MCA electrocoagulation plus TDCS (daily anodal and cathodal 10 Hz, 0.1 mA TDCS for 30 min beginning day 1 after stroke), respectively. Motor function was assessed using the beam walking test (BWT), and density of dendritic spines (DS) and PX1 mRNA expression were compared among groups on days 3, 7, and 14 after stroke. Effects of PX1 blockage on DS in hippocampal neurons after hypoxia-ischemia were observed. TDCS significantly improved motor function on days 7 and 14 after stroke as indicated by reduced BWT scores compared with the MCAO group. The density of DS was decreased after stroke; the TDCS group had increased DS density compared with the MCAO group on days 3, 7, and 14 (all P<0.0001). Cerebral infarction induced increased PX1 mRNA expression on days 3, 7, and 14 (P<0.0001), and the peak PX1 mRNA expression was observed on day 7. TDCS did not decrease the up-regulated PX1 mRNA expression after stroke on day 3, but did reduce the increased post-stroke PX1 mRNA expression on days 7 and 14 (P<0.0001). TDCS increased the DS density after stroke, indicating that it may promote neural plasticity after stroke. TDCS intervention from day 7 to day 14 after stroke demonstrated motor function improvement and can down-regulate the elevated PX1 mRNA expression after stroke.

Design and benchtop validation of a handheld integrated dynamic breast imaging system for noninvasive characterization of suspicious breast lesions

We have developed a portable, handheld, integrated, dynamic breast imaging system that integrates a near infrared tissue oximeter, clinical ultrasound, and two pressure sensors for noninvasive detection of pressure-induced structural and functional dynamics of suspicious breast lesions. A series of benchtop tests were conducted to validate multiple performance characteristics of the integrated dynamic near infrared/ultrasound breast imaging system (idNIRUS), including the reconstruction of the absorptive heterogeneities and the generation of the dynamic compression stimuli. In absorptive heterogeneity testing, we reconstructed the absorption coefficients of transparent polypropylene tubing circulated with a skim milk-India ink mixture and embedded in a gel wax tissue simulating phantom. High linear correlations (R(2) greater than 0.989) were observed between the reconstructed and the measured absorption coefficients of the embedded tubing. In dynamic compression testing, five volunteer operators generated ten successive compression sessions by compressing the idNIRUS imager on a breast self examination wearable model following the computer simulated pressure profile. The manually generated pressure profiles demonstrated an accuracy of 95.7% and operator-dependent variation of less than 5%. The results of the current benchtop tests will help to optimize the most appropriate testing conditions for our future planned clinical trial.

Anemia prevalence among pregnant women and birth weight in five areas in China

OBJECTIVES

To investigate the current prevalence of anemia among pregnant women in different areas of China and the association with birth weight and educational level.

METHODS

A total of 6,413 women aged 24-37 in the third trimester of pregnancy from five areas were randomly selected from all gravidas who gave birth in the hospitals from 1999 to 2003. Blood hemoglobin concentration (Hb) was measured by the cyanomethemoglobin method; Hb <110 g/l was considered as anemia.

RESULTS

The overall prevalence of anemia was 58.6%, ranging from 48.1 to 70.5% in the five areas. There was a significant difference in the prevalence of anemia between women who have mental jobs and those who have physical jobs (52.3 vs. 61.1%, p < 0.01). The prevalence of anemia depended on the level of education: with 52.9, 62.4 and 66.5%, for college, secondary school and primary education, respectively, and the difference was statistically significant (p = 0.005). Results showed that higher birth weight was associated with Hb concentrations ranging from 90 to 140 g/l, whereas lower birth weight occurred below 80 g/l and above 140 g/l Hb.

CONCLUSIONS

The prevalence of anemia in Chinese pregnant women was high both in rural areas and towns. Area of residence, education level and type of job influenced the prevalence of anemia. Low maternal Hb concentrations influenced birth weight.

Atomic structure of PDE4: insights into phosphodiesterase mechanism and specificity

Cyclic nucleotides are second messengers that are essential in vision, muscle contraction, neurotransmission, exocytosis, cell growth, and differentiation. These molecules are degraded by a family of enzymes known as phosphodiesterases, which serve a critical function by regulating the intracellular concentration of cyclic nucleotides. We have determined the three-dimensional structure of the catalytic domain of phosphodiesterase 4B2B to 1.77 angstrom resolution. The active site has been identified and contains a cluster of two metal atoms. The structure suggests the mechanism of action and basis for specificity and will provide a framework for structure-assisted drug design for members of the phosphodiesterase family.

Genome duplications and other features in 12 Mb of DNA sequence from human chromosome 16p and 16q

Several publicly funded large-scale sequencing efforts have been initiated with the goal of completing the first reference human genome sequence by the year 2005. Here we present the results of analysis of 11.8 Mb of genomic sequence from chromosome 16. The apparent gene density varies throughout the region, but the number of genes predicted (84) suggests that this is a gene-poor region. This result may also suggest that the total number of human genes is likely to be at the lower end of published estimates. One of the most interesting aspects of this region of the genome is the presence of highly homologous, recently duplicated tracts of sequence distributed throughout the p-arm. Such duplications have implications for mapping and gene analysis as well as the predisposition to recurrent chromosomal structural rearrangements associated with genetic disease.

Specific inhibition of apoptosis after cold-induced brain injury by moderate postinjury hypothermia

OBJECTIVE

Apoptosis of neuronal cells plays a key role in many developmental and pathological processes of the central nervous system. Deoxyribonucleic acid (DNA) of cells undergoing apoptosis is cleaved by an endonuclease into oligonucleosoma-sized fragments. These fragments can be labeled using in situ terminal deoxynucleotidyl transferase so that the apoptotic cells can be visualized by in situ apoptotic staining. The model of cold-induced rat brain edema was used to further examine this hypothesis. The protective effect of hypothermia was also studied in this model of cold-induced brain injury.

METHODS

Using a terminal deoxynucleotidyl transferase-mediated deoxyuridine 5'-triphosphate-biotin nick end labeling technique, the neuronal cells with DNA fragmentation in different regions of the brains of rats subjected to cold-induced brain injury were detected. The internucleosomal fragments of DNA in apoptotic cells were examined using agarose gel electrophoresis. The animals were randomly divided into three groups: 1) sham (n = 8); 2) cold-induced brain injury, killed at 12, 24, 48, 72, and 168 hours after cold lesion (n = 10 for each time point); 3) hypothermia, both mean temporalis and rectal temperatures were reduced by surface cooling to 32 degrees C (standard deviation, 0.1 degrees C) for 3, 6, and 12 hours (n = 10 for each time point) beginning 1 hour after cold-induced brain injury.

RESULTS

The apoptotic cells were detectable for up to 72 hours after the initial brain injury and reached a peak at approximately 24 to 48 hours, with a mean peak value of 24.29 +/- 5.26, 15.37 +/- 4.10, 15.81 +/- 3.56, 13.94 +/- 2.48, 10.46 +/- 2.23, and 7.68 +/- 2.48% in the cortex, subcortex, white matter, CA1, CA3, and dentate gyrus, respectively, and had a significant increase, compared with the control value (mean +/- standard error, P < 0.01). Agarose gel electrophoresis of DNA extracted from cortex and hippocampus containing apoptotic cells revealed a "DNA ladder" at 180- to 200-base pair intervals. In animals subjected to the same brain injury that underwent 32 degrees C hypothermia, the numbers of apoptotic cells were reduced evidently and DNA fragmentation was inhibited.

CONCLUSION

The data suggest that apoptosis occurs after cold-induced brain injury and that DNA fragmentation may be associated with apoptotic cell death. Moderate hypothermia shows specific effect on inhibition of apoptotic cell death and cellular DNA fragmentation after cold-induced brain injury in rats.

NMR structure of a protein kinase C-gamma phorbol-binding domain and study of protein-lipid micelle interactions

Classical protein kinase C (PKC) family members are activated by the binding of various ligands to one of several cysteine-rich domains of the enzyme. The natural agonist, diacylglycerol (DAG), and the natural product superagonist, phorbol dibutyrate (PDB), activate the enzyme to produce wide-ranging physiological effects. The second cysteine-rich (Cys2) domain of rat brain PKC-gamma was expressed and labeled with 15N and 13C, and the solution structure was determined to high resolution using multidimensional heteronuclear NMR methods. The phorbol binding site was identified by titrating this domain with phorbol-12,13-dibutyrate (PDB) in the presence of organic cosolvents. Titrations of this domain with lipid micelles, in the absence and presence of phorbols, indicate selective broadening of some resonances. The observed behavior indicates conformational exchange between bound and free states upon protein-micelle interaction. The data also suggest that half of the domain, including the phorbol site and one of the zinc sites, is capable of inserting into membranes.

Catalytic activity of the SH2 domain of human pp60c-src; evidence from NMR, mass spectrometry, site-directed mutagenesis and kinetic studies for an inherent phosphatase activity

During solution structural studies it was apparent that the human recombinant pp60c-src SH2 domain (srcSH2, residues 144-249) possessed an inherent phosphatase (Pase) activity. Complexes of U[13C,15N]srcSH2 with unlabeled Ac-pYEEIE (I) were examined using 31P and 1H-detected isotope filtered NMR methods. The presence of a high-affinity complex in equimolar solutions of I and U[13C, 15N]-srcSH2 was demonstrated by chemical shift perturbations, line broadening, and the observation of intermolecular nuclear Overhauser effects from the pY and Ile side-chain protons of I to protons on amino acid residues present in the binding pocket of srcSH2. Solutions containing excess I relative to srcSH2 revealed a slow hydrolysis of I to produce Ac-YEEIE and inorganic phosphate. The hydrolysis rate determined from NMR and HPLC-electrospray ionization mass spectrometry data at 30 degrees C for solutions containing excess I was 0.002-0.003 h-1. srcSH2 also catalyzed the hydrolysis of p-nitrophenyl phosphate (pNPP). Isoelectric focusing gels of a number of mutant srcSH2s demonstrated that this activity comigrated with srcSH2. Km, kcat, and kcat/Km were 3.7 +/- 0.4 mM, 3.1 +/- 0.2 x 10(-2) min-1, and 8.4 +/- 0.4 M-1 min-1, respectively, toward pNPP. The C188A mutant of the srcSH2 domain displayed 15% of the activity displayed by wild-type srcSH2, demonstrating that this residue is not absolutely required for activity. Two additional mutations in the known pY binding site, R178K and R158K, also resulted in decreased pNPPase activity, suggesting that the activity resides in or near this site. The inhibitor profile and pH dependence suggest that this is a novel protein Pase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Solution structure of the human pp60c-src SH2 domain complexed with a phosphorylated tyrosine pentapeptide

Human pp60c-src is a cellular nonreceptor tyrosine kinase that participates in cytosolic signal transduction and has been implicated in the development of malignant tumors in the human breast and colon. Signal transduction is mediated by highly specific interactions between the SH2 domain and receptor phosphorylated tyrosine binding motifs. To elucidate the molecular conformation and interactions in solution, a family of highly resolved nuclear magnetic resonance (NMR) structures was determined for the src SH2 domain complexed with a high-affinity phosphorylated pentapeptide, acetyl-p YEEIE-OH. The 23 structures, generated with a distance geometry (DG) and a dynamical simulated annealing (SA) procedure, satisfied 2072 experimental restraints derived from a variety of multifrequency/multidimensional and isotope-filtered NMR data. Superimposition of residues 143-245 upon the mean coordinate set yielded an atomic rmsd of 0.58 +/- 0.09 A for the N, C alpha, C' atoms and 1.04 +/- 0.08 for all the non-hydrogen atoms. Residues in the ordered secondary structure regions superimpose to 0.29 +/- 0.04 A for the N, C alpha, C' and 0.73 +/- 0.08 A for all the non-hydrogen atoms. The angular order parameter calculated for the phi, psi angles was > 0.9 for 81 of the 106 protein residues. The main protein conformational features are three antiparallel beta-strands that traverse a compact core with an alpha-helix on each side of the core near the N- and C-termini. The observed intermolecular nuclear Overhauser effects (NOE) from the pY, +1E, and +3I residues positioned the ligand in an extended conformation across the SH2 domain surface with the pY and +3I side chains inserted into the protein binding pockets. In general, the protein conformation is consistent with previously reported structures of different SH2 domain complexes determined by X-ray crystallography. However, inter- or intramolecular interactions involving the guanidinium side chains of the solvated R alpha A2 or the buried R beta B5 were not observed at pH = 5.5 or 7.0. If such interactions exist in solution, the absence of any confirming data probably arises from rapid exchange with solvent and/or undetermined dynamic components. Thus, the unrestrained R alpha A2 side chain did not show an amino-aromatic interaction or a hydrogen bond to the -1 carbonyl oxygen as observed in the crystal structures. This result is consistent with the solution structure of a different SH2 domain complex. A more detailed comparison between the crystal structure and the NMR-derived solution structures of the same src SH2 domain complex is presented.(ABSTRACT TRUNCATED AT 400 WORDS)

Solution structure of the amino-terminal fragment of urokinase-type plasminogen activator

The amino-terminal fragment (ATF) of urokinase-type plasminogen activator is a two domain protein which consists of a growth factor and a kringle domain. The 1H, 13C, and 15N chemical shifts of this protein have been assigned using heteronuclear two- and three-dimensional NMR experiments on selective and uniformly 15N- and 15N/13C-labeled protein isolated from mammalian cells that overexpress the protein. The chemical shift assignments were used to interpret the NOE data which resulted in a total of 1299 NOE restraints. The NOE restraints were used along with 27 phi angle restraints and 21 hydrogen-bonding restraints to produce 15 low energy structures. The individual domains in the structures are highly converged, but the two domains are structurally independent. The root mean square deviations (rmsd) between residues 11-46 in the growth factor domain and the mean atomic coordinates were 0.99 +/- 0.2 for backbone heavy atoms and 1.65 +/- 0.2 for all non-hydrogen atoms. For residues 55-130 in the kringle domain, the rmsd was 0.84 +/- 0.2 for backbone heavy atoms and 1.42 +/- 0.2 for all non-hydrogen atoms. The overall structures of the individual domains are very similar to the structures of homologous proteins. However, important structural differences between the growth factor and other homologous proteins were observed in the region which has been implicated in binding the urokinase receptor which may explain, in part, why other growth factors show no appreciable affinity for the urokinase receptor.

NMR determination of the structures of peroxycobalt(III) bleomycin and cobalt(III) bleomycin, products of the aerobic oxidation of cobalt(II) bleomycin by dioxygen

The oxidation of Co(II) bleomycin A2 by dioxygen leads to two products, HO2-Co(III) bleomycin A2 (form I) and Co(III) bleomycin A2 (form II). 1H NMR chemical shift assignments for protons of both forms have been made by two-dimensional NMR spectral techniques. The chemical shifts of protons throughout forms I and II differ from each other and from apobleomycin A2. NOESY spectra reveal a number of intermediate and long-range 1H-1H couplings within the metal-binding domain, between the metal-binding domain and the peptide linker, which connects it and the DNA-binding region of the molecule, and, in form I, between the DNA- and metal-binding domains. Molecular dynamics calculations were carried out based on the NOESY results and an adjustable square pyramidyl ligand geometry around Co(III) composed of nitrogen atoms of the primary and secondary amine groups, pyridine (N5), and amide and imidazole (N1) of the hydroxyhistidine residue. In form I, the bithiazole group folds back across the square pyramid forming a compact structure. Although this conformational feature was not observed in form II, the peptide linker between the metal- and DNA-binding domains in both species shows extensive folding based on a large number of intramolecular interactions.

1H, 13C, and 15N assignments and secondary structure of the FK506 binding protein when bound to ascomycin

The 1H, 13C, and 15N resonances of FKBP when bound to the immunosuppressant, ascomycin, were assigned using a computer-aided analysis of heteronuclear double and triple resonance three-dimensional nmr spectra of [U-15N]FKBP/ascomycin and [U-15N,13C]FKBP/ascomycin. In addition, from a preliminary analysis of two heteronuclear four-dimensional data sets, 3JHN,H alpha coupling constants, amide exchange data, and the differences between the C alpha and C beta chemical shifts of FKBP to random coil values, the secondary structure of FKBP when bound to ascomycin was determined. The secondary structure of FKBP when bound to ascomycin in solution closely resembled the x-ray structure of the FKBP/FK506 complex but differed in some aspects from the structure of uncomplexed FKBP in solution.

Heteronuclear 3D NMR studies of water bound to an FK506 binding protein/immunosuppressant complex

From a series of 15N-resolved 3D ROESY-HMQC and 13C-resolved 3D NOESY-HMQC spectra of the FK506 binding protein (FKBP)/ascomycin complex in H2O, the locations of three tightly bound water molecules were identified. These waters are all buried within the interior of the complex and form an integral part of its structure via a network of hydrogen bonds. Water molecules in identical locations exhibiting a similar hydrogen bonding pattern were also observed in the X-ray crystal structures of FKBP/FK506 [Van Duyne, G. D., Standaert, R. F., Karplus, P. A., Schreiber, S. L., & Clardy, J. (1991) Science 252, 839-842] and FKBP/rapamycin [Van Duyne, G. D., Standaert, R. F., Schreiber, S. L., & Clardy, J. (1991) J. Am. Chem. Soc. 113, 7433-7434]. However, none of the surface waters observed in the X-ray structures were detected in the NMR experiments due to their fast exchange with bulk water. In order to examine the effects of the three internal water molecules on NMR structure determinations of the FKBP/ascomycin complex, two sets of NMR structures were calculated either with or without the waters. By including the three internal waters in the structure calculations, a decrease in the root mean square deviation and improved angular order parameters was observed for FKBP residues in the vicinity of the water molecules. In addition, subtle conformational differences were observed between NMR structures generated either with or without the waters.(ABSTRACT TRUNCATED AT 250 WORDS)

A general method for assigning NMR spectra of denatured proteins using 3D HC(CO)NH-TOCSY triple resonance experiments

A general approach for assigning the resonances of uniformly 15N- and 13C-labeled proteins in their unfolded state is presented. The assignment approach takes advantage of the spectral dispersion of the amide nitrogen chemical shifts in denatured proteins by correlating side chain and backbone carbon and proton frequencies with the amide resonances of the same and adjacent residues. The 1H resonances of the individual amino acid spin systems are correlated with their intraresidue amide in a 3D 15N-edited 1H,1H-TOCSY-HSQC experiment, which allows the spin systems to be assigned to amino acid type. The spin systems are then linked to the adjacent i-1 spin system using the 3D H(C)(CO)NH-TOCSY experiment. Complete 13C assignments are obtained from the 3D (H)C(CO)NH-TOCSY experiment. Unlike other methods for assigning denatured proteins, this approach does not require previous knowledge of the native state assignments or specific interconversion rates between the native and denatured forms. The strategy is demonstrated by assigning the 1H, 13C, and 15N resonances of the FK506 binding protein denatured in 6.3 M urea.

Three-dimensional structure of the FK506 binding protein/ascomycin complex in solution by heteronuclear three- and four-dimensional NMR

A high-resolution three-dimensional solution structure of the FKBP/ascomycin complex has been determined using heteronuclear multidimensional nuclear magnetic resonance spectroscopy (NMR) and a distance geometry/simulated annealing protocol. A total of 43 structures of the complex, including 3 tightly bound water molecules, were obtained using 1958 experimental restraints consisting of 1724 nuclear Overhauser effect (NOE) derived distances, 66 chi 1 and 46 phi angular restraints, and 122 hydrogen bond restraints. The root mean square (rms) deviations between the 43 FKBP/ascomycin solution structures and the mean atomic coordinates were 0.43 +/- 0.08 A for the backbone heavy atoms and 0.80 +/- 0.08 A for all non-hydrogen atoms. Angular order parameters for the family of 43 conformations were calculated to determine dihedral convergence. Order parameters for phi, psi, and chi 1 angles exhibited mean values of 0.98, 0.97, and 0.95, respectively, while the mean of the chi 2 order parameter was 0.63. Comparisons were made between the FKBP/ascomycin complex and two NMR-derived solution structures of unbound FKBP and the X-ray crystal structure of an FKBP/FK506 complex. Differences were observed between the FKBP/ascomycin complex and uncomplexed FKBP for residues 33-45 and 78-92. In contrast, the NMR-derived solution structure of the FKBP/ascomycin complex and the X-ray crystal structure of the FKBP/FK506 complex were very similar. Differences between the two complexes were mainly observed in the conformations of some highly solvent exposed side chains.

Side chain and backbone assignments in isotopically labeled proteins from two heteronuclear triple resonance experiments

Two multi-dimensional heteronuclear NMR experiments are described for assigning the resonances in uniformly 15N- and 13C-labeled proteins. In one experiment (HCNH-TOCSY), the amide nitrogen and proton are correlated to the side-chain protons and carbons of the same and preceding residue. In a second triple resonance experiment (HC(CO)NH-TOCSY), the amide nitrogen and proton of one residue is correlated exclusively with the side-chain proton and carbon resonances of the preceding residue by transferring magnetization through the intervening carbonyl. The utility of these two experiments for making sequential resonance assignments in proteins is illustrated for [U-15N,13C]FKBP (107 residues) complexed to the immunosuppressant, ascomycin.

Stereospecific assignments and chi 1 rotamers for FKBP when bound to ascomycin from 3JH alpha,H beta and 3HN,H beta coupling constants

3JH alpha,H beta and 3JN,H beta coupling constants were measured for isotopically labeled FKBP when bound to the immunosuppressant, ascomycin, using a 1H-coupled 3D HCCH-TOCSY and 15N-coupled 3D HSQC-TOCSY experiment, respectively. From an analysis of these two sets of coupling constants, stereospecific beta-proton assignments and chi 1 rotamers for FKBP have been obtained. All of the chi 1 rotamers were consistent with the chi 1 angles measured in the X-ray crystal structure of the FKBP/FK506 complex, suggesting that the structures of the two complexes are similar.

NMR studies of an FK-506 analog, [U-13C]ascomycin, bound to FK-506-binding protein

Multidimensional, heteronuclear NMR methods were used to determine the complete 1H and 13C resonance assignments for [U-13C]ascomycin bound to recombinant FKBP, including stereospecific assignment of all 22 methylene protons. The conformation of ascomycin was then determined from an analysis of NOEs observed in a 13C-edited 3D HMQC-NOESY spectrum of the [U-13C]ascomycin/FKBP. This structure is found to be quite different from the solution structure of the two forms of uncomplexed FK-506. However, it is very similar to the X-ray crystal structure of FK-506 bound to FKBP, rms deviation = 0.56 A. The methods used for resonance assignment and structure calculation are presented in detail. Furthermore, FKBP/ascomycin NOEs are reported which help define the structure of the ascomycin binding pocket. This structural information obtained in solution was compared to the recently described X-ray crystal structure of the FKBP/FK-506 complex.

Reaction of DNA-bound Co(II)bleomycin with dioxygen

The aerobic oxidation of Co(II)bleomycin bound to calf thymus DNA has been investigated in relation to the mechanism of reaction in solution in the absence of DNA. Kinetics of dioxygenation of the Co(II) complex were followed by spectrophotometric and electron spin resonance spectroscopy as well as dioxygen analysis. The reaction is slower than when carried out in solution; its rate is inversely related to the ratio of DNA base pairs to Co(II)bleomycin. The subsequent oxidation reaction, observed spectrophotometrically and by dioxygen analysis, is second order in cobalt complex. The calculated second order rate constant is also inversely related to the base pair to metal complex ratio. Once this ratio exceeds three, the reaction rate slows significantly with each additional increment of DNA added to the starting reaction mixture. Taking advantage of the high stability of O(2)-Co(II)bleomycin bound to greater than a 3-fold excess of DNA base pairs, it could be demonstrated that the rate constant for oxidation of two O(2)-Co(II)bleomycin molecules is much slower than that for O(2)-Co(II)bleomycin plus Co(II)bleomycin. With the same technique it was observed that the metal centers of O(2)-Co(II)bleomycin and Fe(II)bleomycin also undergo oxidation. The binding to DNA of both solution products of the oxidation of Co(II)bleomycin by O2 was examined by 1H NMR spectroscopy. Peroxy-Co(III)bleomycin, Form I, binds with higher affinity than Co(III)bleomycin, Form II. At lower ionic strength, the size of the DNA binding site for each form is about 2 base pairs/molecule of drug.

Reaction of Co(II)bleomycin with dioxygen

The reaction of Co(II)bleomycin with dioxygen has been investigated. Dioxygen binds to the Co(II) complex within the time of mixing according to electron spin resonance and uv-visible spectroscopy and dioxygen analysis. Then, two dioxygenated cobalt centers react, releasing 1 mol of O2 and forming an intermediate characterized by a few highly shifted 1H NMR resonances and loss of the ESR spectrum. This is thought to be a dioxygen-bridged dimer of cobalt bleomycin molecules. Time-dependent absorbance and dioxygen measurements yield the same second order rate constant for this step of the reaction. According to uv-visible and NMR spectral analysis, the intermediate decays into diamagnetic products in a first order rate process. High performance liquid chromatography and 1H NMR studies demonstrate that the product contains two bleomycin species of equal concentration. One component is Co(III)bleomycin, designated Form II. The other is the peroxide adduct of Co(III)bleomycin, Form I, as determined by direct determination of hydrogen peroxide, which is slowly released from the product at low pH. In contrast, hydrogen peroxide is readily detected during the reaction of Co(II)Blm with O2. In isolation, Form I is unstable at pH 7 and is converted within 24 h into a mixture of Form I and Form II.

Experimental evaluation of blood-brain barrier permeability using colloidal gold particles as tracers in early-stage brain injury

We used 46 rabbits for the study of blood-brain barrier (BBB) permeability quantitatively in early-stage brain injury by a dropping weight method. The animals were divided into two groups: control group and brain injury group. Both Evans' blue and colloidal gold (CG) particles were utilized for evaluation of BBB permeability alteration. Three different sizes of CG 5, 10 and 15 nm in diameter were employed as tracers for a quantitative investigation of BBB changes by light and electron microscopes respectively. In addition, the brain water contents were determined. The preliminary data indicated that an increase of BBB permeability began 30 minutes after the injury with a few of 5 or 10 nm CG particles present in the endocytic pits and endothelial microvilli, and the augmentation of BBB permeability reached its peak 6 hours after the injury. More CG tracers penetrated into the precapillary arterioles, venules or capillaries through the opening of tight junctions of BBB and by vesicular transportation. The variation of the brain water contents was closely correlated to the above-mentioned BBB changes. It is suggested that the vasogenic cerebral edema was mainly caused by the augmentation of BBB permeability.