The incidence of surgical site infections in China

Surgical site infections (SSIs) are a common type of healthcare-associated infection. We performed a literature review to demonstrate the incidence of SSIs in mainland China based on studies since 2010. We included 231 eligible studies with ≥30 postoperative patients, comprising 14 providing overall SSI data regardless of surgical sites and 217 reporting SSIs for a specific site. We found that the overall SSI incidence was 2.91% (median; interquartile range: 1.05%, 4.57%) or 3.18% (pooled; 95% confidence interval: 1.85%, 4.51%) and the SSI incidence varied remarkably according to the surgical site between the lowest (median, 1.00%; pooled, 1.69%) in thyroid surgeries and the highest (median, 14.89%; pooled, 12.54%) in colorectal procedures. We uncovered that Enterobacterales and staphylococci were the most common types of micro-organisms associated with SSIs after various abdominal surgeries and cardiac or neurological procedures, respectively. We identified two, nine, and five studies addressing the impact of SSIs on mortality, the length of stay (LOS) in hospital, and additional healthcare-related economic burden, respectively, all of which demonstrated increased mortality, prolonged LOS, and elevated medical costs associated with SSIs among affected patients. Our findings illustrate that SSIs remain a relatively common, serious threat to patient safety in China, requiring more action. To tackle SSIs, we propose to establish a nationwide network for SSI surveillance using unified criteria with the aid of informatic techniques and to tailor and implement countermeasures based on local data and observation. We highlight that the impact of SSIs in China warrants further study.

Association between dietary flavonol intake and mortality risk in the U.S. adults from NHANES database

Using updated National Health and Nutrition Examination Survey (NHANES) follow-up data, and a large nationwide representative sample of adult U.S. citizens, the aim of this study was to explore the relationship between dietary flavonol intake, all-cause and cause-specific mortality risks. In this prospective cohort study based on NHANES (2007-2008, 2009-2010, and 2017-2018), a total of 11,679 participants aged 20 years and above were evaluated. The amount and type of food taken during a 24-h dietary recall were used to estimate dietary flavonol intake, which includes total flavonol, isorhamnetin, kaempferol, myricetin, and quercetin. Each analysis of the weighted data was dealt with in accordance with the NHANES reporting requirements' intricate stratification design. The Cox proportional risk regression model or Fine and Gray competing risks regression model were applied to evaluate all-cause and cause-specific mortality risks, respectively. The follow-up period was calculated using the time interval between the baseline and the death date or December 31, 2019 (whichever occurs first). Each data analysis was performed between October 1, 2023, and October 22, 2023. Dietary flavonol intake included total flavonol, isorhamnetin, kaempferol, myricetin, and quercetin. Up to December 31, 2019, National Death Index (NDI) mortality data were used to calculate mortality from all causes as well as cause-specific causes. A total of 11,679 individuals, which represents 44,189,487 U.S. non-hospitalized citizens, were included in the study; of these participants, 49.78% were male (n = 5816), 50.22% were female (n = 5, 863); 47.56% were Non-Hispanic White (n = 5554), 18.91% were Non-Hispanic Black (n = 2209), 16.23% were Mexican American (n = 1895), and 17.30% were other ethnicity (n = 2021); The mean [SE] age of the sample was 46.93 [0.36] years, with a median follow-up of 7.80 years (interquartile range, 7.55-8.07 years). After adjusting covariates, Cox proportional hazards models and fine and gray competing risks regression models for specific-cause mortality demonstrated that total flavonol intake was associated with all-cause (HR 0.64, 95% CI 0.54-0.75), cancer-specific (HR 0.45, 95% CI 0.28-0.70) and CVD-specific (HR 0.67, 95% CI 0.47-0.96) mortality risks; isorhamnetin intake was associated with all-cause (HR 0.72, 95% CI 0.60-0.86), and cancer-specific (HR 0.62, 95% CI 0.46-0.83) mortality risks; kaempferol intake was associated with all-cause (HR 0.74, 95% CI 0.63-0.86), and cancer-specific (HR 0.62, 95% CI 0.40-0.97) mortality risks; myricetin intake was associated with all-cause (HR 0.77, 95% CI 0.67-0.88), AD-specific (HR 0.34, 95% CI 0.14-0.85), and CVD-specific (HR 0.61, 95% CI 0.47-0.80) mortality risks; quercetin intake was associated with all-cause (HR 0.66, 95% CI 0.54-0.81), cancer-specific (HR 0.54, 95% CI 0.35-0.84), and CVD-specific (HR 0.61, 95% CI 0.40-0.93) mortality risks; there was no correlation observed between dietary flavonol intake and DM-specific mortality. According to the current study, all-cause, AD, cancer, and CVD mortality risks declined with increased dietary flavonoid intake in the U.S. adults. This finding may be related to the anti-tumor, anti-inflammatory, and anti-oxidative stress properties of flavonol.

Persistent organic pollutants exposure and risk of autism spectrum disorders: A systematic review and meta-analysis

Accumulating number of epidemiological studies has recently proposed that improvement in the risk of autism spectrum disorders (ASD) is associated with persistent organic pollutants (POPs) exposure. However, evidence from current researches is limited and inconsistent. Thus, we conducted a systematic review and meta-analysis to investigate the potential associations comprehensively. We systematically and extensively searched two electronic databases (PubMed and EMBASE) from inception to July 3, 2022 and an updated search was performed before submission. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were derived from stratified random-effects meta-analyses by type of exposure and outcome. We also tested the potential heterogeneity across studies, conducted sensitivity analysis and evaluated publication bias. A total of 20 studies were finally included in our study. Meta-analytical effect estimates indicated a positive association between prenatal exposure to PCB-138, PCB-153 and PCB-170 and an increased risk of ASD, with OR of 1.89 (95% CI = 1.21-2.95, I2 = 0%), 1.61 (95% CI = 1.05-2.47, I2 = 0%) and 1.46 (95% CI = 1.03-2.06, I2 = 0%) respectively. In contrast, PFDA was found inversely associated with the risk of ASD (OR = 0.70, 95% CI = 0.52-0.94, I2 = 0%). The level of evidence supporting a link between ASD risk and exposure to PCB-138, PCB-153, PCB-170, and PFDA was respectively categorized as low, low, moderate, and low. In summary, this systematic review and meta-analysis suggest that exposure to PCB-138, PCB-153, and PCB-170 correlates with a heightened risk of ASD, with evidence levels rated as "low", "low", and "moderate", respectively. In contrast, PFDA exposure appears to be inversely associated with ASD risk, with a "low" level of supporting evidence. However, due to the limited number of studies available for each exposure and outcome pairing, these results should be interpreted with caution. Sufficiently powered studies are needed to validate our findings.

Association between sleep-wake schedules and myopia among Chinese school-aged children and adolescents: a cross-sectional study

BACKGROUND

This study aimed to investigate the relationship between sleep-wake schedules and self-reported myopia in the pediatric population.

METHODS

In this cross-sectional study in 2019, school-aged children and adolescents in the Baoan District of Shenzhen City were sampled using a stratified cluster sampling approach. Sleep-wake schedules of children were determined by a self-administered questionnaire. The age that participants first reported using myopia correction glasses or contact lenses was used to identify those with myopia. Pearson χ² test was used to examine differences in myopia prevalence among participants with different characteristics. Multivariate logistic regression, adjusted for potential confounding variables, was applied to examine the relationship between sleep-wake schedule and risk of self-reported myopia, and a stratification analysis by school grade was also performed.

RESULTS

A total of 30,188 students were recruited. In this study, the overall prevalence of myopia was 49.8%, with prevalence rates of 25.6%, 62.4%, and 75.7% for primary, junior high, and senior high school students, respectively. Students with irregular sleep-wake times reported a higher prevalence of myopia than those with regular sleep-wake times. Nighttime sleep duration of < 7 hours/day (h/d) (OR = 1.27, 95%CI: 1.17-1.38), no daytime nap (OR = 1.10, 95%CI: 1.03-1.18), irregular weekday bedtime (OR = 1.11, 95%CI: 1.05-1.17), irregular weekday wake time (OR = 1.21, 95%CI: 1.12-1.30), weekend bedtime delayed > = 1 h/d (OR = 1.20, 95%CI: 1.11-1.29, P < 0.001), weekend wake time delayed > = 1 h/d (OR = 1.11, 95%CI: 1.03-1.19), irregular sleep-wake time on weekdays (OR = 1.13, 95%CI: 1.07-1.19), and social jetlag > = 1 h (OR = 1.08, 95%CI: 1.03-1.14) were likely to be associated with increased risks of self-reported myopia after adjusting age, sex, grade, parental education level, family income, parental myopia, academic record, and academic workload. When stratified by school grade, we observed that nighttime sleep duration < 7 h/d, no daytime naps, and irregular sleep-wake time on weekdays were significantly associated with self-reported myopia in primary school students.

CONCLUSION

Insufficient sleep and irregular sleep-wake schedules can increase the risk of self-reported myopia in children and adolescents.

Association between PM1 Exposure and Lung Function in Children and Adolescents: A Systematic Review and Meta-Analysis

The detrimental effects of PM_2.5 and PM₁₀ (particulate matter less than 2.5 or 10 μm) on human respiratory system, including lung function, have been widely assessed. However, the associations between PM₁ (particulate matter of less than 1 μm) and lung function in children and adolescents are less explored, and current evidence is inconsistent. We conducted a meta-analysis of the literature on the association between PM₁ and lung function in children and adolescents to fill this gap. With no date or language constraints, we used a combination of MeSH (Medical Subject Headings) terms and free text to search PubMed, EMBASE and Web of Science databases through, 1 October 2022 for "PM₁ exposure" and "lung function". A total of 6420 relevant studies were identified through our initial search, and seven studies were included in our study. In this meta-analysis, the fixed effect and random effects statistical models were used to estimate the synthesized effects of the seven included studies. For every 10 μg/m³ increase in short-term PM₁ exposure, forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) decreased by 31.82 mL (95% CI: 20.18, 43.45), 32.28 mL (95% CI: 16.73, 48.91), 36.85 mL/s (95% CI: 15.33, 58.38) and 34.51 mL/s (95% CI: 19.61, 49.41), respectively. For each 10 μg/m³ increase in long-term PM₁ exposure, FVC, FEV₁, PEF and MMEF decreased by 102.34 mL (95% CI: 49.30, 155.38), 75.17 mL (95% CI: 39.61, 110.73), 119.01 mL/s (95% CI: 72.14, 165.88) and 44.94 mL/s (95% CI: 4.70, 85.18), respectively. Our study provides further scientific evidence for the harmful effects of PM₁ exposure on lung function in children and adolescents, indicating that exposure to PM₁ is detrimental to pulmonary health. To reduce the adverse health effects of air pollution on children and adolescents, effective preventive measures should be taken.

Association between Short-Term Exposure to Ozone and Heart Rate Variability: A Systematic Review and Meta-Analysis

At present, ambient air pollution poses a significant threat to patients with cardiovascular disease (CVD). The heart rate variability (HRV) is a marker of the cardiac autonomic nervous system, and it is related to air pollution and cardiovascular disease. There is, however, considerable disagreement in the literature regarding the association between ozone (O₃) and HRV. To further investigate the effects of short-term exposure to O₃ on HRV, we conducted the first meta-analysis of relevant studies. The percentage change of HRV indicator(s) is the effect estimate extracted for the quantitative analysis in this study. In our meta-analysis, per 10 ppb increase in O₃ was significantly associated with decreases in the time-domain measurements, for standard deviation of the normal-to-normal (NN) interval (SDNN) -1.11% (95%CI: -1.35%, -0.87%) and for root mean square of successive differences (RMSSD) -3.26% (95%CI: -5.42%, -1.09%); in the frequency-domain measurements, for high frequency (HF) -3.01% (95%CI: -4.66%, -1.35%) and for low frequency (LF) -2.14% (95%CI: -3.83%, -0.45%). This study showed short-term exposure to O₃ was associated with reduced HRV indicators in adults, which suggested that the cardiac autonomic nervous system might be affected after O₃ exposure, contributing to the association between O₃ exposure and CVD risk.

Carbon Nanotubes-Based Fuel Cell for Cr(VI) Removal and Electricity Generation

A fuel cell, an energy transducer, can convert chemical energy into electrical energy. In this work, graphite felt (GF) loaded with polypyrrole (PPy) and carboxylic carbon nanotubes (CNTs-COOH) was used as a cathode (GF/PPy/CNTs-COOH) in a double-chamber nonbiofuel cell (D-nBFC) to remove Cr(VI) efficiently. Therein, Na₂S₂O₃ in an alkaline solution and Cr(VI) in a strongly acidic solution were employed as anode and cathode solutions, respectively. An agar salt bridge, consisting of saturated KCl solution, was used to transport ions between the anode and cathode. This system suggested that the removal efficiency of Cr(VI) could reach 99.6%. The maximum current, power, and power density could achieve 136.8 μA, 18.7 μW, and 20.8 mW/m² at 90 min, respectively. Additionally, GF/PPy/CNTs-COOH also had good electrocatalytic stability and reusability after four cycles, which played an important role in the development of the D-nBFC system. Therefore, this study provides an environmentally friendly and efficient method to remove Cr(VI) and generate electricity simultaneously.

A sodium hyposulfite fuel cell for efficient Cr(VI) removal

This work shows a strategy of reducing hexavalent chromium (Cr(VI)) by sodium hyposulfite (Na₂S₂O₃) with self-generated electricity via a dual-chamber non-biological fuel cell (D-nBFC). Therein, Na₂S₂O₃ was electro-oxidized on graphite felt (GF) at anode and Cr(VI) in strong acidic solution was electro-reduced at GF/CCP cathode (GF decorated with conductive carbon paint (CCP)). Additionally, an agar salt bridge, consisting of saturated KCl solution, was introduced to form complete circuit by offering ions. The results showed that Cr(VI) was reduced to trivalent chromium (Cr(III)) and the D-nBFC system could produce electricity in this process. This system could obtain a high Cr(VI) removal efficiency (97.0%), 110 μA maximum current, and 13.4 mW m^-2 maximum power density in 4 h. In addition, the proposed system had high reusability after five cycles and the relative standard deviation was only 3.4% (n = 5). Thus, this D-nBFC system provides a promising and eco-friendly method for treatment of Cr(VI) pollution and generating electricity simultaneously, and also has potential application value for other heavy metals remediation.

Analysis on clinical characteristics and drug resistance of Candida parapsilosis bloodstream infections in West China Hospital, China, from 2012 to 2015

OBJECTIVE OF THE STUDY

Candida parapsilosis has emerged as an important cause of bloodstream infections (BSI) in the health care setting. We aimed to describe the clinical characteristics and drug resistance of C. parapsilosis BSI in West China Hospital of Sichuan University in China and provide the basis for prevention and treatment of this disease.

PATIENTS

We retrospectively collected and analyzed patients presented in our hospital reported with C. parapsilosis BSI from January 2012 to January 2015.

MATERIALS AND METHODS

Data regarding age, gender, the department distribution, the potential clinical risk factors and the result of clinical treatment and prognosis were retrospectively evaluated. As to the antifungal drugs susceptibility testing, we used Etest method for determining the minimum inhibitory concentrations (MICs) of amphotericin B, fluconazole, voriconazole, caspofungin and flucytosine for all the clinical isolates of C. parapsilosis. Standard quality strains were used as the controls.

RESULTS

Most of the patients with C. parapsilosis BSI were over 60-year-old (37.5%) or within 10years old (28.13%). Among patients, 78.13% came from an intensive care unit or had undergone surgery in the past several months. The major risk factors associated with an increased risk of infection included the use of broad-spectrum antibacterial drugs and deep vein indwelling. The overall mortality of patients with C. parapsilosis BSI was 31.25%. The drug sensitivity tests revealed that all isolates were sensitive to amphotericin B and flucytosine. Two and 1 isolates were found susceptible to fluconazole and voriconazole in a dose-dependent manner, respectively. Only 1 isolate was resistant to fluconazole. 4 isolates (12.5%) were medium sensitive to caspofungin, but no one showed drug resistance.

CONCLUSION

In summary, elders and newborns were more vulnerable to C. parapsilosis infections. C. parapsilosis was found frequently as pathogens leading to BSI in patients admitted to ICU and departments of surgery and often causing a high mortality rate. C. parapsilosis rarely showed drug resistance at present, so common antifungal drugs could be used for treatment. Recommendations for using of antifungal drugs focused on paying close attention to possible drug resistance trend.

Testing Hadronic Interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_{CM}=110-170  TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.

Thermal conductivity of oxidized gamma-graphyne

Molecular dynamics simulations are employed to investigate the thermal conductivity of oxidized gamma-graphyne with the different oxygen coverage and at different tensile strain.

Hetastarch with hypertonic saline loading is a better choice for the maintenance of systemic and pulmonary circulation during general and epidural anesthesia

AIM

Sufficient volume load prior to major surgery is important for better management of anesthesia. In this study we assessed systemic and pulmonary hemodynamic stabilization following a load of hypertonic saline plus hydroxyethyl starch (HHS) solution during anesthesia in elective hepatobiliary surgical patients.

METHODS

Thirty-six hepatobiliary surgical patients, ASA physical status I~II, were randomly and double-blindly divided into: HHS (4 mL/kg) group, hydroxyethyl starch (7 mL/kg) group (HES group) and Ringer's solution (7 mL/kg) group (RL group). All the patients underwent general anesthesia and epidural anesthesia. Mean pulmonary artery pressure (MPAP), pulmonary artery wedge pressure (PAWP), right ventricular-stroke work (RVSW) and pulmonary vascular resistance (PVR) were recorded to monitor pulmonary circulation; systemic vascular resistance (SVR), cardiac output (CO) and stroke volume (SV) were recorded to monitor systemic circulation. These parameters were recorded before infusion (T0), 10 min after infusion (T1), 5 min after induction (T2), 5, 10 and 20 min after intubation (T3, T4 and T5, respectively).

RESULTS

In pulmonary circulation, MPAP, PAWP and RVSW were increased at T1 compared to T0 in both HES and HHS groups, the latter being more marked at T1. Pulmonary PVR was decreased in both HHS and HES groups compared to RL group during T2 to T5. In systemic circulation, SVR was decreased in both HHS and HES groups during T1 to T5 compared to RL group. CO and SV were increased at T1 compared to T0 in both HHS and HES groups, and they also increased during T1 to T5 in HHS group compared to RL group.

CONCLUSION

HHS solution was superior in maintaining systemic and pulmonary circulation during general anesthesia combined epidural anesthesia.

Radioiodine therapy for patients with differentiated thyroid cancer after thyroidectomy: direct comparison and network meta-analyses

BACKGROUND AND OBJECTIVES

The effective dose of radioiodine 131 (I-131) ablation for patients with differentiated thyroid cancer (DTC) after thyroidectomy was unclear, so we tried to find out which activity is the best using the methods of direct comparison and network meta-analyses.

METHODS

Direct comparison and network meta-analyses were conducted with ADDIS software. Randomized controlled trials (RCT) which compared different activities of I-131 after thyroidectomy for adult patients with DTC were included. The outcomes we evaluated were successful remnant ablation rate, duration of stay in an isolation unit, the number of subsequent I-131 treatments required, recurrence rate, and adverse effects.

RESULTS

Thirteen RCT (3352 patients) were included. Our network meta-analysis demonstrated that there were not any statistical differences in successful ablation rates among all comparisons except 100 mCi vs 15 mCi. However, rank probability plot suggested 60 mCi might be the best in successful ablation rate. For recurrence rate, both direct comparison and network meta-analyses showed no statistical differences among 100 mCi, 60 mCi, and 30 mCi; 100 mCi was associated with a smaller number of patients who required subsequent I-131 treatments and longer stay in an isolation unit than 30 mCi without any more adverse events.

CONCLUSION

Because of conflicting results between direct comparison and network meta-analyses, we failed to conclude which activity of I-131 is the best in successful ablation rates.

Acinetobacter baumannii isolates associated with community-acquired pneumonia in West China

Acinetobacter baumannii has emerged as an important cause of community-acquired infection. To characterize the microbiological and genotypic features of community-associated Acinetobacter baumannii, 32 isolates associated with community-acquired pneumonia were collected. These isolates were diverse in resistance patterns and had multiple clonal origins. bla(OXA-23) was the main acquired oxacillinases-encoding gene detected.

Assessment of continuum mechanics models in predicting buckling strains of single-walled carbon nanotubes

This paper presents an assessment of continuum mechanics (beam and cylindrical shell) models in the prediction of critical buckling strains of axially loaded single-walled carbon nanotubes (SWCNTs). Molecular dynamics (MD) simulation results for SWCNTs with various aspect (length-to-diameter) ratios and diameters will be used as the reference solutions for this assessment exercise. From MD simulations, two distinct buckling modes are observed, i.e. the shell-type buckling mode, when the aspect ratios are small, and the beam-type mode, when the aspect ratios are large. For moderate aspect ratios, the SWCNTs buckle in a mixed beam-shell mode. Therefore one chooses either the beam or the shell model depending on the aspect ratio of the carbon nanotubes (CNTs). It will be shown herein that for SWCNTs with long aspect ratios, the local Euler beam results are comparable to MD simulation results carried out at room temperature. However, when the SWCNTs have moderate aspect ratios, it is necessary to use the more refined nonlocal beam theory or the Timoshenko beam model for a better prediction of the critical strain. For short SWCNTs with large diameters, the nonlocal shell model with the appropriate small length scale parameter can provide critical strains that are in good agreement with MD results. However, for short SWCNTs with small diameters, more work has to be done to refine the nonlocal cylindrical shell model for better prediction of critical strains.

Cell membrane changes of structure and function in protein kinase inhibitor-induced polyploid cells

Exogenous cyclic AMP has been thought to be a chemical without marked pharmacological effect until now, as it is not capable of penetrating the cell membrane in most eucaryotic cells. The present study obtained results consistent with those of most previous studies, showing that exogenous cyclic AMP itself did not interfere with the cell cycle even at the high dose of 100 microM. However, it was found that K252a, a potent inhibitor of protein kinases including protein kinase C, induced DNA re-replication, i.e. DNA synthesis at a elevated DNA ploidy in cells that had not undergone cytokinesis (leading to polyploidization), and that exogenous cyclic AMP markedly potentiated the K252a-induced polyploidization at a very low dose similar to the effective dose of membrane-permeable cyclic AMP analogue dibutyryl cyclic AMP. These findings suggested that the cell membrane changed during the formation of polyploid cells. This supposition was confirmed by scanning electron microscopy to observe structural changes and by determination of cellular attachment to investigate functional changes.

A three-dimensional human head finite element model and power flow in a human head subject to impact loading

A three-dimensional finite element model of the human head is presented. The model has been validated against two sets of experimental results. To assess injury likelihood of the head subjected to impact loading, the structural intensity (SI) methodology is introduced in accordance with the prevailing practice in experimental biomechanics. SI is a vector quantity indicating the direction and magnitude of power flow inside a dynamically loaded structure. In this paper, the SI field inside the head model is computed for three cases, namely frontal, rear and side impacts. The results for the three cases have revealed that there exist power flow paths. The skull is, in general, a good energy flow channel. The study has also revealed the high possibility of spinal cord injury due to wave motion inside the head.

[Difference of several major nutrients accumulation in vegetable and cereal crop soils]

Investigation and determination of several major nutrients in different types of vegetable and cereal crop soils were carried out in the Guanzhong Plain in Shaanxi Province. The results showed that organic matter, nitrogen, phosphorus and potassium accumulated more in the 0-200 cm profile of vegetable soils than in that of cereal crop soils. However, the accumulation degrees were different with different nutrient forms. The total amount of nitrate-N in the soil profile of plastic greenhouse and usual vegetable field was 1520.9 kg.hm-2 and 1358.8 kg.hm-2, being 5.2 and 4.5 times higher than that in the cereal crop fields respectively. The total amount of available-P was respectively 978.1 kg.hm-2 and 503.3 kg.hm-2 in the two vegetable soils, and 136.2 kg.hm-2 in cereal crop soils, and the former two were 6.2 and 2.7 times higher than the latter. For other nutrients, organic matter in cereal crop soil was 249.4 Mg.hm-2, and that in plastic greenhouse and usual vegetable soil was 280.5 Mg.hm-2 and 269.3 Mg.hm-2, respectively, which were only 12.5% and 8.0% higher than that in cereal crop soils. The total-N in plastic greenhouse and usual vegetable soils was 37.5 Mg.hm-2 and 32.7 Mg.hm-2, which was 36.2% and 18.6% higher than that (27.5 Mg.hm-2) in cereal crop soils, respectively. The ammonium-N was 211.5 kg.hm-2 and 197.8 kg.hm-2, which was 29.6% and 21.2% higher than that (163.2 kg.hm-2) in cereal crop soils. The available-K was 6567.8 kg.hm-2 and 5523.6 kg.hm-2, which was 30.6% and 9.8% higher than that (5029.7 kg.hm-2) in cereal crop soils. Furthermore, serious nutrient leaching occurred in vegetable soil profiles due to over-fertilization and irrigation.

[Nitrate accumulation in vegetables and its residual in vegetable fields]

Determinations of 11 kinds, 48 varieties of vegetables were carried out at different seasons. The results showed that nitrate-N concentrations in 20 vegetables reached Pollution Level 4 (NO3(-)-N > 325 mg.kg-1), which accounted for 41.7% of the total number of the sampled vegetables and included all of the leafy, and most of the melon, root, onion and garlic vegetables. Among them, 5 leafy vegetables even exceeded Level 4 (NO3(-)-N > 700 mg.kg-1). Although leafy vegetables were usually apt to heavily accumulate nitrate, most of them were with nitrate-N concentrations lower than Level 3 (NO3(-)-N < 325 mg.kg-1) in leave blades. Further investigation showed that vegetable soils accumulated more nitrates in each layer from 0 cm to 200 cm than did cereal crop soil. The total amount of residual nitrate-N was 1358.8 kg.hm-2 in the 200 cm soil profile of usual vegetable fields, and 1411.8 kg.hm-2 and 1520.9 kg.hm-2 in the 2-yaers and the 5-years long plastic greenhouse fields respectively, however that in the cereal crop fields was only 245.4 kg.hm-2. Nitrate residual in vegetable soils formed serious threats to underground water in vegetable growing areas.

Biodynamic response of shipboard sitting subject to ship shock motion

Underwater shock can produce very high accelerations, resulting in severe human injuries. In this paper, a shock-structure-human interaction model is proposed to study the biodynamic response of a shipboard sitting subject to ship motion induced by underwater shock (ship shock motion) wherein, the human body is modeled using a lumped parameter system with the parameters obtained from dynamic tensile tests. The results obtained from the human model used in this paper and living human drop test are also compared. Numerical results have revealed the characteristics of human response to ship shock motion. The part in direct contact with the structure (like the pelvis) is much more vulnerable than other parts (like the head). The influences of structural damping and stiffness on the peak loads acting on the human body are investigated. Both damping and stiffness have important influences on the pelvis, but have much less influences on other parts. Injury criteria in the literature are also summarized to facilitate injury assessment.

[Expressions of five protein kinase C isoforms in salivary adenoid cystic carcinoma]

OBJECTIVE

The protein kinase C (PKC) family of isoforms plays the key role in the regulation of cellular events, including cell proliferation, differentiation and canceration. Previous work from our laboratory has shown the alteration of PKC and its inhibitor activities in salivary adenoid cystic carcinoma (SACC) [Sun Changfu, et al. West China Journal of Stomatology, 1998, 16(3): 201-203]. This study aimed to further explore the relationship between PKC isoforms and canceration of SACC.

METHODS

Expressions of five isoforms of PKC (alpha, beta I, beta II, epsilon and delta) were examined in cytosolic and membranous fraction of specimen homogenates from SACCs and were compared with the adjacent normal tissues by immunoblotting. Equal amounts of cytosolic and membrane protein from control and experimental groups were simultaneously subjected to sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), transferred to nitrocellulose membranes, and reacted with first and second antibodies; Color development and image analysis were performed.

RESULTS

1. Cytosolic PKC-alpha, PKC-beta I, and PKC-beta II were expressed in SACCs and adjacent normal tissues. The Expressions of these three cytosolic isoforms were reduced significantly in SACCs compared with the adjacent normal tissues; 2. Membranous PKC-alpha was only detected in SACCs and the membranous translocation of cytosolic PKC-alpha was also seen. 3. The expressions of PKC-epsilon and PKC-delta were not detected in both SACCs and adjacent normal tissues.

CONCLUSION

There was close relationship between changes of expression of PKC isoforms (alpha, beta I, beta II) and carcinogenesis of SACC. We postulated that there may be relationship between the membranous translocation of PKC-alpha and hematogenous lung metastasis in SACC.

[Changes on the protein kinase C activity of alveolar macrophages in patients with idiopathic pulmonary fibrosis]

OBJECTIVE

To study the changes on protein kinase C(PKC) activity of alveolar macrophages (AM) in patients with idiopathic pulmonary fibrosis(IPF).

METHOD

The PKC activity of AM in 9 healthy volunteers and 15 patients with IPF was investigated by radioactivity measuring.

RESULTS

The total, cytosolic and particulate fraction PKC activity of AM in bronchoalveolar lavage fluid(BALF) from patients with IPF were higher than those from control group(P < 0.01 and P < 0.05). The total and the membrane fraction PKC activity had positive correlation with the number of cells in BALF(r = 0.8135, P < 0.01 and r = 0.5917, P < 0.05) respectively.

CONCLUSION

As a bypass of transmembrane signal transduction, PKC was suggested to be involved in the development of IPF.

Saikosaponin b2 induces differentiation without growth inhibition in cultured B16 melanoma cells

Treatment with 5 microM of saikosaponin (SS) b2 for 30 days was found to induce differentiation of B16 melanoma cells, with potentiation of expressions of melanogenesis and tyrosinase. To explore the mechanism of this effect, we observed the cell growth, cell cycle and morphology, and found that SSb2 did not affect any of these parameters. That is, SSb2 induced the differentiation of B16 melanoma cells without growth inhibition or cytotoxicity under conditions of low dose and long-term treatment. Phorbol ester, a protein kinase C (PKC) activator, markedly inhibited the expressions of melanogenesis and tyrosinase in both the control B16 melanoma cells and the long-term treated B16 melanoma cells. Down-regulation of the PKC activity may be involved in the effects of SSb2.

Different manner of DNA synthesis in polyploidizations of meth-A and B16F10 cell lines

Polyploidization of Meth-A and B16-F10 cells by demecolcine was examined using flow cytometry (FCM). In the presence of demecolcine, both cell lines were polyploidized to more than 16c DNA content. A marked difference was observed in the durations of S phase of polyploidy. The S-phase duration of Meth-A cells was doubly increased with ploidy, but that of B16F10 cells remained constant. When the rate of DNA synthesis in the polyploidizing cells was examined through the BrdU-uptake experiments, it was confirmed that the level of DNA-synthesis rate was constant in Meth-A cells but increased in B16F10 cells. The cellular content of c-Myc protein in polyploidized cells was also examined using anti-c-Myc monoclonal antibody. The c-Myc level of Meth-A cells was constant regardless of the ploidy but that of B16F10 cells increased with ploidy. Thus, the c-Myc content seems to be related to the duration of S phase in polyploidy.

Saikosaponin b2-induced apoptosis of cultured B16 melanoma cell line through down-regulation of PKC activity

Saikosaponin (SS) b2 was found to inhibit the proliferation of B16 melanoma cells. To explore this mechanism, we employed flow cytometry to determine the distribution of DNA content. The cell cycle of B16 melanoma cells was accumulated in the G1 phase followed by induction of apoptosis. This suggests that SSb2-induced proliferation inhibition is caused by G1 phase accumulation and that apoptosis induction is G1-phase-accumulation dependent. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, did not interfere with the proliferation and did not induce apoptosis of B16 melanoma cells by itself. However, PMA significantly abolished these effects of SSb2 in including proliferation inhibition and apoptosis induction. Down-regulation of the PKC activity may be involved in the effect of SSb2.