Environmental pollution of fluoroquinolones and its relationship with nitrogen cycling mediated by microorganisms.

Fluoroquinolone antibiotics (FQs) are one of the most widely used antibiotics, which are new pollutants with 'pseudo persistence' in the environment, causing great ecological risks. FQs could change the structure and function of microbial communities and affect nitrogen cycling mediated by microorganisms. Consequently, FQs would change the composition of various types of nitrogen in the environment and exert a significant impact on the global nitrogen cycling. We encapsulated the distribution of FQs in the environment and its impacts on nitrogen cycling mediated by microorganisms, explained the role of FQs in each key process of nitrogen cycling, aiming to provide an important reference for revealing the ecological effects of FQs. Generally, FQs could be detected in various environmental media, with significant differences in the concentration and types of FQs in different environments. Ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin are the four types of FQs with the highest detection frequency and concentration. The effect of FQs on nitrogen cycling deeply depends on typical characteristics of concentration and species. FQs mainly inhibit nitrification by reducing the abundance of amoA gene related to ammoxidation process and the abundance and composition of ammoxidation bacteria. FQs inhibits nitrification by reducing the abundance and composition of microbial communities. The denitrification process is mainly inhibited due to the reduction of the activity of related enzymes and the abundance of genes such as narG, nirS, norB, and nosZ genes, as well as the abundance and composition of denitrifying functional microorganisms. The process of anammox is restricted due to the reduction of the abundance, composition and hzo gene abundance of anaerobic anammox bacteria. FQs lead to the reduction of active nitrogen removal and the increase of N2O release in the environment, with further environmental problems such as water eutrophication and greenhouse effect. In the future, we should pay attention to the effects of low concentration FQs and complex antibiotics on the nitrogen cycling, and focus on the effects of FQs on the changes of nitrogen cycle-related microbial monomers and communities.

Behavioral and ecotoxicology of sulfonamide metabolites in the aquatic environment.

Sulfonamides (SAs) are the first broad-spectrum synthetic antimicrobial agents used in human health and veterinary medicine. The majority of SAs entering human body is discharged into aquatic environment in the form of parent material or metabolites. The residues of SAs and their metabolites in the aquatic environment and the development of drug resistance can be serious threats to ecosystems and human health. We summarized recent advances in the research of SAs. The main metabolite types of SAs and the distribution characteristics of metabolites in different aquatic environments were introduced. The ecotoxicology of SAs metabolites, especially the distribution and hazards of sulfonamide resistance genes (sul-ARGs), were discussed with emphasis. Finally, the future research works were proposed. This paper could provide basic information for further research on SAs.

Biogeochemical behavior and ecological environmental effects of fluoroquinolones.

Synthetic fluoroquinolones (FQs) are the third most commonly used antibiotics in the world and play an extremely important role in antibacterial drugs. The excessive use and discharge will alter ecological environment, with consequence on human health and global sustainable development. It is therefore of great significance for scientific use and management of FQs to systematically understand their biogeochemical behavior and eco-environmental effects. After drug administration in humans and animals, only a small part of FQs are transformed in vivo. The main transformation processes include formylation, acetylation, oxidation and cleavage of piperazine ring, defluorination and decarboxylation of aromatic core ring, etc. About 70% of the original drug and a small amount of transformed products would be migrated to the environment through excretion. After entering the environment, FQs and their transformation products mainly exist in environmental media such as water, soil and sediment, and undergo migration and transformation processes such as adsorption, photolysis and biodegradation. Adsorption facilitates transfer of FQs from medium to another. The photolysis mainly affects the C7-amine substituents of FQs, whereas the core structure of FQs remains intact. Biodegradation mainly refers to the degradation of FQs by microorganisms and microalgae, including piperazine modification of the piperazine ring such as acetylation and formylation, partial or complete ring cleavage, core structure decarboxylation, defluorination and conjugation formation. The migration and transformation processes of FQs cannot completely eliminate them from the environment. Instead, they would become "pseudo-persistent" pollutants, which seriously affect the behavior, growth and reproduction of algae, crustaceans and fish, change biogeochemical cycle, destroy aquatic environment, and stimulate microbial resistance and the generation of resistance genes. In the future, more in-depth studies should be conducted on the environmental behavior of FQs and their impacts on ecological environment, the risk assessment of microbial resistance and resistance genes of FQs, and the mechanism and effect of micro-biodegradation of FQs.

Pancreatic neuroendocrine tumor: prediction of the tumor grade using magnetic resonance imaging findings and texture analysis with 3-T magnetic resonance.

PURPOSE: The purpose of this study was to evaluate the performance of magnetic resonance imaging (MRI) findings and texture parameters for prediction of the histopathologic grade of pancreatic neuroendocrine tumors (PNETs) with 3-T magnetic resonance. PATIENTS AND METHODS: PNETs are classified into Grade 1 (G1), Grade 2 (G2), and Grade 3 (G3) tumors based on the Ki-67 proliferation index and the mitotic activity. A total of 77 patients with pathologically confirmed PNETs met the inclusion criteria. Texture analysis (TA) was applied to T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) maps. Patient demographics, MRI findings, and texture parameters were compared among three different histopathologic subtypes by using Fisher's exact tests or Kruskal-Wallis test. Then, logistic regression analysis was adopted to predict tumor grades. ROC curves and AUCs were calculated to assess the diagnostic performance of MRI findings and texture parameters in prediction of tumor grades. RESULTS: There were 31 G1, 29 G2, and 17 G3 patients. Compared with G1, G2/G3 tumors showed higher frequencies of an ill-defined margin, a predominantly solid tumor type, local invasion or metastases, hypo-enhancement at the arterial phase, and restriction diffusion. Four T2-based (inverse difference moment, energy, correlation, and differenceEntropy) and five DWI-based (correlation, contrast, inverse difference moment, maxintensity, and entropy) TA parameters exhibited statistical significance among PNETs (P<0.001). The AUCs of six predicting models on T2WI and DWI ranged from 0.703-0.989. CONCLUSION: Our data indicate that MRI findings, including tumor margin, texture, local invasion or metastases, tumor enhancement, and diffusion restriction, as well as texture parameters can aid the prediction of PNETs grading.

The prognostic value of pretreatment tumor apparent diffusion coefficient values in nasopharyngeal carcinoma.

BACKGROUND: Diffusion-weighted MR imaging (DWI) has increasingly contributed to the management of nasopharyngeal carcinoma (NPC) patients. The objective of this paper was to explore the prognostic significance of apparent diffusion coefficient (ADC) values in 93 NPC patients. METHODS: This retrospective study included 93 newly diagnosed NPC patients. Pretreatment ADC values were determined and compared with patients' age, gender, alcohol intake, smoking, tumor volume, pathological type, tumor stage, and nodal stage. Using the Kaplan-Meier method, overall survival (OS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS) were calculated and the values compared between the low and high ADC groups. Multivariate analysis of ADC values and other 9 clinical parameters was performed using a Cox proportional hazards model to test the independent significance for OS, LRFS and DMFS. RESULTS: The mean ADC value for the initial nasopharyngeal tumors was 0.72 × 10-3 mm2/s (range: 0.48-0.97 × 10-3 mm2/s). There was no significant difference between pretreatment ADCs and patient' gender, age, smoking, alcohol intake, or tumor stage. A significant difference in the ADCs for different N stages (P = 0.022) and correlation with initial tumor volume (r = -0.26, P = 0.012) were observed. In comparison, the ADC value for undifferentiated carcinoma was lower than that for other 3 pathological types. With a median follow-up period of 50 months, the 3-year and 5-year OS rates were 88.2% and 83.3%, respectively, 3-year and 5-year LRFS rates were 93.5% and 93.3%, respectively, and 3-year and 5-year DMFS rates were 83.9% and 83.3%, respectively. Patients with tumor ADC values ≥0.72 × 10-3 mm2/s exhibited longer OS and LRFS periods compared with tumor ADC values <0.72 × 10-3 mm2/s, with P values 0.036 and 0.018, respectively. In addition, patients with deaths or recurrences or distant metastasis had significant lower ADC values than those without disease failures. According to a multivariate analysis using the Cox proportional hazard test, ADC values showed a significant correlation with OS (P = 0.0004), LRFS (P = 0.0009), and DMFS (P < 0.0001), respectively. CONCLUSIONS: Pretreatment tumor ADC values supposed to be a noninvasive important prognostic parameter for NPC.

[Distribution and Sources of n-alkanes in Surface Seawater of Jiaozhou Bay].

Hydrocarbons emitted by human activities probably constitute the largest class of contaminants that are present in coastal areas, because of widespread use of fossil fuels for power generation and logistics, and accidental spillages. The chemical composition of hydrocarbon mixtures found in the marine environment allowed the identification of relative contributions of different natural and anthropogenic sources. Identification of these hydrocarbons, especially n-alkanes, could act as tracers for the possible sources. To evaluate n-alkanes concentrations with emphasis on source analysis, surface water without visible oil was collected from the cruise in April 2016. Determination and quantification were performed by solvent extraction and gas chromatography-mass spectrometry. Various molecular diagnostic parameters were used to assess the contribution of different sources and origin of n-alkanes in surface seawater of Jiaozhou Bay. Concentrations of total dissolved n-alkanes(C11-C37) were between 1.756-39.09 µg·L-1 with a high carbon number predominance profile without odd-even carbon number preference. The n-alkane concentrations varied spatially depending on the distance away from main input sources and the ability of water exchange. It was at a higher concentration in the northeast and west coastal areas, as well as the mouth of Jiaozhou Bay. And concentrations were relatively lower in the inner area and outside of Jiaozhou Bay. In the sea area with strong water exchange, concentrations of total n-alkanes were around 2.196 µg·L-1, which could be considered as the environmental background level of n-alkanes in Jiaozhou Bay. Those n-alkanes were dominated with C24, with a slightly odd carbon number preference in low carbon n-alkanes and an even carbon number preference in high carbon n-alkanes. The values of CPI for the whole range of n-alkanes series, low carbon n-alkanes, and high carbon n-alkanes were 0.949, 1.026, and 0.980, respectively. Diagnostic indices and curves indicated that the dominant inputs of those n-alkanes were from marine biogenic input such as algae and marine bacteria. The concentration profiles of n-alkanes in other areas were characterized by no odd-even predominance in the range of C21-C33 with peaks center at C24 which were indicative of anthropic contributions as emission sources. N-alkanes dominating with anthropic sources comprised a high proportion(83.7%) of total n-alkanes. Activities of harbors and ships were the main contributors of Jiaozhou Bay n-alkanes. Physical processes, such as evaporation and dilution, were the principal weathering mechanisms. Because of its sufficient environmental capacity, Jiaozhou Bay was still moderately contaminated with petroleum.

Apparent diffusion coefficient measurements with diffusion-weighted imaging for differential diagnosis of soft-tissue tumor.

OBJECTIVES: To evaluate the diagnostic potential of apparent diffusion coefficient (ADC) values of diffusion-weighted imaging (DWI) in distinguishing malignant and benign soft-tissue tumors. MATERIALS AND METHODS: Published studies were retrieved through comprehensive search in various computerized databases. High-quality studies relevant to ADC values of DWI in differential diagnosis of soft-tissue tumors were screened using our stringent inclusion and exclusion criteria for this meta-analysis. The standard mean difference with 95% confidence interval (95% CI) was estimated. Statistical analyses were performed using the STATA statistical software (Stata Co., College Station, TX, USA). RESULTS: Thirteen cohort studies were finally included, and these studies provided the required information on the diagnostic value of diffusion magnetic resonance imaging in soft-tissue tumors. The 13 studies contained a combined total of 344 malignant soft tumors and 315 benign soft tumors. The results of our meta-analysis revealed that mean ADC value in patients with malignant soft-tissue tumor decreased significantly in comparison with the ADC values obtained in patients with benign soft-tissue tumor (P < 0.001). Country-stratified analysis suggested that ADC value might play a predictive role in the differential diagnosis of soft-tissue tumors in China (P = 0.007), Egypt (P < 0.001), Germany (P = 0.001), Japan (P = 0.049), and The Netherlands (P < 0.001). CONCLUSION: Our results provide strong evidence that patients diagnosed with malignant soft-tissue tumors have low ADC values of DWI compared to those with benign soft-tissue tumors. Therefore, ADC measurements with DWI may be reliable in differential diagnosis of soft-tissue tumors.

[Distribution and Environmental Significances of Radionuclides in the Sediment of the Changyi Coastal Wetland].

The radionuclides contents in the surface sediments and sediment cores were determined by gamma spectrometry method. The distribution of radionuclides and its indication to material sources, human activities and other sedimentary environmental evolution events were discussed and the sedimentation rate was estimated. The results showed that the average activity concentrations of 238U,232Th, 226Ra and40K in the surface sediment were (54.4±11.7), (57.9±9.7), (28.6±4.3) and (542±21) Bq·kg-1, respectively. Regional differences of radioactivity level reflected the material sources and influences of human activities on the sediment characteristics. According to the vertical distribution of excess 210Pb, the sedimentation rate of high tidal areas was estimated at 0.23 cm·a-1. In the sediment core, the variable coefficients of 238U,232Th and 226Ra contents were high. According to the vertical profiles of 238U,226Ra and 238U/226Ra ratio, the process of sedimentation could be divided into four periods: period of slow deposition, period of dramatic change in sedimentary environment caused by great migration of the Yellow River channels, period of stable deposition after the Yellow River ran into one single channel, and period of alternate degradation and growth under the influence of human activities. The vertical variation of radionuclides in the sediment core could serve as an effective environmental indicator since it could record the environmental evolution processes of the coastal wetland.

Gd-EOB-DTPA-enhanced magnetic resonance imaging for bile duct intraductal papillary mucinous neoplasms.

AIM: To investigate gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) of intraductal papillary mucinous neoplasms of the bile duct (IPMN-B). METHODS: The imaging findings of five cases of IPMN-B which were pathologically confirmed at our hospital between March 2012 and May 2013 were retrospectively analyzed. Three of these cases were diagnosed by duodenal endoscopy and biopsy pathology, and two cases were diagnosed by surgical pathology. All five patients underwent enhanced and non-enhanced computed tomography (CT), magnetic resonance cholangiopancreatography, and Gd-EOB-DTPA-enhanced MRI; one case underwent both Gd-EOB-DTPA-enhanced MRI and positron emission tomography-CT. The clinical data and imaging results for these cases were compared and are presented. RESULTS: Conventional imaging showed diffuse dilatation of bile ducts and multiple intraductal polypoid and papillary neoplasms or serrated changes along the bile ducts. In two cases, Gd-EOB-DTPA-enhanced MRI revealed dilated biliary ducts and intraductal tumors, as well as filling defects caused by mucin in the dilated bile ducts in the hepatobiliary phase. Gd-EOB-DTPA-enhanced MRI in one case clearly showed a low-signal tumor in the hepatobiliary phase, similar to what was seen by positron emission tomography-CT. In two patients, routine inspection was unable to discern whether the lesions were inflammation or tumors. However, Gd-EOB-DTPA-enhanced MRI revealed a pattern of gradual enhancement during the hepatobiliary phase, and the signal intensity of the lesions was lower than the surrounding liver parenchyma, suggesting tissue inflammation in both cases, which were confirmed by surgical pathology. CONCLUSION: Gd-EOB-DTPA-enhanced MRI reveals the intraductal mucin component of IPMN-B in some cases and the extent of tumor infiltration beyond the bile ducts in invasive cases.

Early changes in apparent diffusion coefficient as an indicator of response to sorafenib in hepatocellular carcinoma.

OBJECTIVE: The relationship between apparent diffusion coefficient (ADC) and chemotherapy has been established. However, whether ADC could be considered as a measure for monitoring response to sorafenib in hepatocellular carcinoma (HCC) has not been demonstrated. This study was to investigate the ADC changes of advanced HCC under sorafenib treatment. METHODS: Athymic mice with HepG2 xenografts were allocated to two groups: control and sorafenib (40 mg/kg, bid). T2 and diffusion images were acquired at each time point (0, 10, 14, and 18 d post-therapy). Tumor volume and changes in ADC were calculated. RESULTS: Tumor volumes on Days 10, 14, and 18 after treatment showed significant decreases in the sorafenib-treated group compared with the control. Pretreatment ADC values were not significantly different between the control and treated groups. A slow increase in ADC in the peripheral zone of tumors appeared in the treated group, which was significantly higher compared with the control group on Days 10, 14, and 18. In the central part of tumors on Day 10 after treatment, an increase in ADC appeared in the treated and control groups, the ADC of the control group being significantly lower compared with the treated tumors. From Day 10 to Day 14, the ADC map showed a progressive decrease in the central region of tumors in the treated and control groups. However, this change is more significant in the treated groups. CONCLUSIONS: Early changes in mean ADC correlated with sorafenib treatment in HCC, which are promising indicators for predicting sorafenib response in this carcinoma.

[CT and MRI findings in patients with autoimmune pancreatitis].

OBJECTIVE: To evaluate computed tomography (CT) and magnetic resonance imaging (MRI) findings in patients with autoimmune pancreatitis (AIP). METHODS: The imaging findings of pancreas and extra-pancreas in 24 patients with AIP were retrospectively reviewed. Among them, CT scan was performed in 18 patients, MRI in 11, and bGth CT and MRI in 10. RESULTS: The pancreas showed diffuse enlargement (25%, 6/24), focal enlargement (37. 5%, 9/24), combined enlargement (25%, 6/24) ,and no enlargement (12. 5%, 9/24). Unenhanced CT showed hypoattenuation in AIP area (n = 2) . After intravenous injection of contrast medium, 17 patients showed abnormal contrast enhancement in the affected pancreatic parenchyma, including hypoattenuation during the arterial phase (50%, 9/18) and hyper attenuation during the delayed phase (94. 4%, 17/18). Precontrast MRI showed abnormal signal intense (n =9), including hypointense on T1-weight images (T1 WI) (n = 7), hyperintense (n = 7) and hypointense (n = 2) on T2-weight images (TIWI). Enhanced MRI demonstrated abnormal contrast enhancement within lesions (n = 11), including hypoattenuation during the arterial phase (81. 8%, 9/11) and good enhancement during the delayed phase (100%, 11111). A capsule-like rim was seen around pancreas (37. 5%, 9/24), among which CT detected in 6 out of 18 patients and MRI found in 7 out of 11 patients.The main pancreatic duct lumen within lesions has no visualization (100%, 24/24) and upstream dilation of the main pancreatic duct (n = 8) , ranging from 2. 2 to 4. 5 mm(mean 3. 1 0. 47 mm) in diameter. Narrowing of the common bile duct was shown in 14 patients. Miscellaneous findings were: infiltration of extrapancreatic vein (n = 9) and artery (n = 1); mild fluid collection around pancreas (n = 2); pseudocysts (n = 3). Fourteen patients also presented one or more of the following extrapancreatic imaging findings: narrowing of the intra-hepatic bile duct or hilar duct (n = 5); thickening of gallbladder wall (n = 5); fibrosis in mesenteric (n = 2), in retroperitoneal (n = 2) and in ligamentum teres hepatis (n = 1); renal involvement (n = 3); peri-pancreatic or para-aortic lymphadenopathy (n = 10); and ulcerative colitis (n = 3). CONCLUSION: AIP display some characteristic CT and MRI imaging features: sausage-like change of the pancreas; capsule-like rims around lesions; delayed contrast enhancement in the affected pancreatic parenchyma; segment or diffuse pancreatic duct stenosis but mild upstream dilation and extrapancreatic organs involvement. CT and MRI findings combining with serological tests and pancreas biopsy can assist physicians to make accurate and timely diagnosis.

[MRI scan of striatum volume in healthy adults].

OBJECTIVE: To examine the age, sex, and hemispheric differences in volume of the striatum by MRI in healthy adults. METHODS: The volumes of the bilateral caudate nucleus and putamen were measured on MR images in 100 healthy right-handed adults (18-70 y). RESULTS: The volume of bilateral caudate nucleus and putamen in healthy adults was (8.42 +/-0.88) cm(3) and (8.90 +/-0.89) cm(3), which were decreased with aging (for caudate nucleus r=-0.727, P<0.001; for putamen r=-0.709, P<0.001). The average annual shrinkage rate was 0.52 % in the caudate nucleus and 0.50 % in the putamen. There were no gender differences in the volume of the striatum, however, the age-related shrinkage of the striatum was more evident in men than that in women. The volume of the left caudate nucleus (t=4.43, P<0.001) and the putamen (t=4.88, P<0.001) was greater than that of its right counterpart. CONCLUSION: Bilateral age-related shrinkage of the striatum is found in healthy adults, which is more evident in men than that in women. In both sexes, significant leftward asymmetry in volume of the caudate nucleus and the putamen is found.

[Evaluation of kidney oxygen bioavailability in acute renal failure by blood oxygen level dependent magnetic resonance imaging].

OBJECTIVE: To assess the kidney oxygen bioavailability in acute renal failure using blood oxygen level dependent (BOLD) magnetic resonance (MR) imaging. METHODS: Twenty-one patients with acute renal failure, including 18 patients with oliguric renal failure, 1 nonoliguric acute renal failure and 2 functional renal failure were enrolled in the study; 20 healthy subjects served as controls. All subjects received renal functional MR examination. BOLD MR imaging with 16 gradient-recalled-echoes on a 1.5-T scanner were performed. R2(*)(1/sec) values of the cortex and medulla and R2(*) ratio of the medulla to cortex (R2(*) ratio of M/C) of the renal were recorded respectively. RESULTS: The R2(*) values of the medulla was higher than those of the cortex in controls (17.64 +/-1.86/sec vs 13.73 +/-0.49/sec, P<0.00). The R2(*) ratio of M/C in controls was 1.28 +/-0.06. The R2(*) values of the medulla (13.31 +/-4.28/sec) and cortex (12.25 +/-2.41/sec) and the R2(* ) ratio of M/C (1.01 +/-0.25) in oliguric renal failure were lower than those in controls (P <0.05). Patients with functional renal failure and nonoliguric acute renal failure had higher R2(*) values in cortex and medulla and higher R2(*) ratio of M/C than those of controls. CONCLUSION: BOLD MRI demonstrates that decreased R2(*) values of cortex and medulla suggest lower oxygen bioavailability in acute renal failure and decreased R2(*)ratio of M/C suggests the disappearance of a steep cortico-medullary gradient of oxygen.

Diagnostic value of the fluoroscopic triggering 3D LAVA technique for primary liver cancer.

BACKGROUND: Primary liver cancer (PLC) is one of the common malignant tumors. Liver acquisition with acceleration volume acquisition (LAVA), which allows simultaneous dynamic enhancement of the hepatic parenchyma and vasculature imaging, is of great help in the diagnosis of PLC. This study aimed to evaluate application of the fluoroscopic triggering 3D LAVA technique in the imaging of PLC and liver vasculature. METHODS: The clinical data and imaging findings of 38 adults with PLC (22 men and 16 women; average age 52 years), pathologically confirmed by surgical resection or biopsy, were collected and analyzed. All magnetic resonance images were obtained with a 1.5-T system (General Electrics Medical Systems) with an eight-element body array coil and application of the fluoroscopic triggering 3D LAVA technique. Overall image quality was assessed on a 5-point scale by two experienced radiologists. All the nodules and blood vessel were recorded and compared. The diagnostic accuracy and feasibility of LAVA were evaluated. RESULTS: Thirty-eight patients gave high quality images of 72 nodules in the liver for diagnosis. The accuracy of LAVA was 97.2% (70/72), and the coincidence rate between the extent of tumor judged by dynamic enhancement and pathological examination was 87.5% (63/72). Displayed by the maximum intensity projection reconstruction, nearly all cases gave satisfactory images of branches III and IV of the hepatic artery. Furthermore, small early-stage enhancing hepatic lesions and the parallel portal vein were also well displayed. CONCLUSIONS: Sequence of LAVA provides good multi-phase dynamic enhancement scanning of hepatic lesions. Combined with conventional scanning technology, LAVA effectively and safely displays focal hepatic lesions and the relationship between tumor and normal tissues, especially blood vessels.

[Asymmetry in internal capsule detected with magnetic diffusion tensor imaging].

OBJECTIVE: To investigate the asymmetry of fibers in the posterior limb of the internal capsule with diffusion tensor imaging. METHODS: Twenty-nine volunteers (right-handers: 20, left-handers: 9) were enrolled in this study. All the data were obtained using a 1.5 tesla scanner (Signa EXCITE II. GE Medical Systems). The parameters including apparent diffusion coefficient (ADC), fractional anisotropy (FA) and eigenvalue lambda1, lambda2, lambda3 were acquired from the posterior limb of the internal capsule in both hemisphere of brain, and paired t-test was used for statistical differences between the hemisphere. RESULTS: No differences of ADC and lambda1 were found among the right-handers, but FA in the internal capsule of left hemisphere was larger than that in the right (0.72+/-0.03 compared with 0.70 +/-0.04, P=0.001), and lambda2, lambda3 in the left was lower than that in the right [(4.39+/-0.32 compared with 4.50+/-0.33)x10(-3) mm(2)/s, P=0.016 and (2.19 +/-0.34 compared with 2.29 +/-0.40)x10(-3) mm(2)/s, P=0.024, respectively]. In contrast to the results among the right-handers, all parameters in the left-handers showed no statistical differences. CONCLUSION: The fibers in the posterior limb of the internal capsule of left hemisphere might be well sheathed with myelin among right-handers.

[Are there gender differences in iron contents of adult brain: an in vivo susceptibility weighted imaging study].

OBJECTIVE: To investigate the gender-related difference in the iron contents of the human brain. METHODS: The brain iron levels were evaluated in vivo in 78 healthy adult volunteers using a noninvasive magnetic resonance method termed susceptibility weighted phase imaging. The subjects consisted of 40 males and 38 females, with the mean age of 41.5+/-11.9 and 45.2+/-15.9, respectively. The phase values were measured on the corrected phase images in the globus pallidus, putamen, caudate, substantia nigra, red nucleus, thalamus and frontal white matter. Phase values of these regions measured from the subjects aged over 30 were correlated with published values of brain iron contents in normal adults to check the validity of the data. Covariance models were used to evaluate the gender effect on the brain iron concentration, with age as the covariate, controlling for the linear effects of age. RESULTS: A strongly negative correlation was showed between the phase values of this study and the reference values (r=-0.796, P=0.032). No significant gender-related difference in the brain iron concentration was found in any regions of interest (P>0.05). CONCLUSION: Gender differences in the iron contents of the adult human brain are not found in this study.

[Different patterns of aversive emotion regulation in homosexual and heterosexual men].

OBJECTIVE: To compare the differences between homosexual and heterosexual men in the pattern of induced aversive emotion regulation. METHODS: Ten healthy homosexual men and 10 heterosexual men were investigated by functional magnetic resonance imaging under three types of visual sexual stimuli designed by Block. SPM2 software was used for data analysis. RESULTS: Same levels of negative emotions of homosexual men and heterosexual were induced by female-female and male-male erotic stimuli respectively. Activations of same brain regions including prefrontal gyrus, temporal gyrus, occipital gyrus and cerebellum were observed in two groups. However, there were significant differences in the side of hippocampus and precuneus. Activations of right cingulate cortex were observed in homosexual men, but not in heterosexual men. CONCLUSION: There are some differences in the patterns of aversive emotion regulation between homosexual and heterosexual men.

[Development of the driving cycle-based mobile emission model (DCMEM)].

Vehicle specific power (VSP) and engine stress (ES) were introduced to reflect the driving characteristics of vehicles in China. Emission rates of 60 BIN based on VSP and ES for light-duty vehicles were calculated on the basis of the on-board emission test data in 5 cities of China. The driving cycle-based mobile emission model (DCMEM) was developed to simulate CO, NOx and HC emission factors of light-duty vehicles for different cities or driving cycles. The differences in CO and NOx emission factors between the DCMEM simulation results and the emissions testing results were less than 10%, and less than 18% for HC.

[Application study of IVE vehicle emission model].

This paper introduced IVE model and presented the method to quantify the main parameters by taking Beijing city as a case. Emissions from different vehicle fleets of Beijing were calculated using IVE model. The results show that emissions factors of buses and trucks were much higher, especially for PM, which were 14 and 44 times those of passenger cars. The daily CO, VOC, NO, and PM emissions of vehicles in Beijing city were 2767.4, 182.5, 353.8 and 7.1 t respectively. Common light duty vehicles were the main emission source of CO and VOC, with the contribution of 42.0% and 34.7% respectively, Trucks were the largest contributor of NO, and PM emissions, with the contribution of 66.3% and 83.0% respectively. The methodology and calculating results of MOBILE6 and IVE model were compared, and advantages of IVE model's application in China were discussed.

Real-world vehicle emission factors in Chinese metropolis city--Beijing.

The dynamometer tests with different driving cycles and the real-world tests are presented. Results indicated the pollutants emission factors and fuel consumption factor with ECE15 + EUDC driving cycle usually take the lowest value and with real world driving cycle occur the highest value, and different driving cycles will lead to significantly different vehicle emission factors with the same vehicle. Relative to the ECE15 + EUDC driving cycle, the increasing rate of pollutant emission factors of CO, NOx and HC are - 0.42-2.99, -0.32-0.81 and -0.11-11 with FTP75 testing, 0.11-1.29, -0.77-0.64 and 0.47-10.50 with Beijing 1997 testing and 0.25-1.83, 0.09-0.75 and - 0.58-1.50 with real world testing. Compared to the carburetor vehicles, the retrofit and MPI + TWC vehicles' pollution emissionfactors decrease with different degree. The retrofit vehicle (Santana) will reduce 4.44%-58.44% CO, -4.95%-36.79% NOx, -32.32%-33.89% HC, and -9.39%-14.29% fuel consumption, and especially that the MPI + TWC vehicle will decrease CO by 82.48%-91.76%, NOx by 44.87%-92.79%, HC by 90.00%-93.89% and fuel consumption by 5.44%-10.55%. Vehicles can cause pollution at a very high rate when operated in high power modes; however, they may not often operate in these high power modes. In analyzing vehicle emissions, it describes the fraction of time that vehicles operate in various power modes. In Beijing, vehicles spend 90% of their operation in low power modes or decelerating.