Defining the optimal technique for endoscopic ultrasound shear wave elastography: a combined benchtop and animal model study with comparison to transabdominal shear wave elastography

Background/Aims@#Shear wave elastography (SWE) is used for liver fibrosis staging based on stiffness measurements. It can be performed using endoscopic ultrasound (EUS) or a transabdominal approach. Transabdominal accuracy can be limited in patients with obesity because of the thick abdomen. Theoretically, EUS-SWE overcomes this limitation by internally assessing the liver. We aimed to define the optimal technique for EUS-SWE for future research and clinical use and compare its accuracy with that of transabdominal SWE. @*Methods@#Benchtop study: A standardized phantom model was used. The compared variables included the region of interest (ROI) size, depth, and orientation and transducer pressure.Porcine study: Phantom models with varying stiffness values were surgically implanted between the hepatic lobes. @*Results@#For EUS-SWE, a larger ROI size of 1.5 cm and a smaller ROI depth of 1 cm demonstrated a significantly higher accuracy. For transabdominal SWE, the ROI size was nonadjustable, and the optimal ROI depth ranged from 2 to 4 cm. The transducer pressure and ROI orientation did not significantly affect the accuracy. There were no significant differences in the accuracy between transabdominal SWE and EUS-SWE in the animal model. The variability among the operators was more pronounced for the higher stiffness values. Small lesion measurements were accurate only when the ROI was entirely situated within the lesion. @*Conclusions@#We defined the optimal viewing windows for EUS-SWE and transabdominal SWE. The accuracy was comparable in the non-obese porcine model. EUS-SWE may have a higher utility for evaluating small lesions than transabdominal SWE.

Clinical effects of robot-assisted esophageal hiatal hernia repair and laparoscopic esophageal hiatal hernia repair: a retrospective comparative study / 中华外科杂志

Objective: To analyze the short-term clinical effects of robot-assisted and laparoscopic repair of the hiatal hernia. Methods: The clinical data of 56 patients underwent minimally invasive hiatal hernia repair from January 2021 to January 2022 in the Department of Minimally Invasive Surgery, Hernias and Abdominal Wall Surgery, People's Hospital of Xinjiang Uygur Autonomous Region were retrospectively analyzed. There were 32 males and 24 females, aging (59.7±10.7) years (range: 28 to 75 years). All patients were divided into laparoscopy group (n=27) and robot group (n=29) according to surgical procedures. Perioperative conditions, hospital stay, and improvement in symptoms before and after surgery were compared between the two groups by the t test, Wilcoxon rank-sum test and χ2 test. Results: All surgical procedures were successfully completed, without conversion to laparotomy or change in operation mode. There were no serious complications related to the operation. The intraoperative blood loss of the robot group was less than that of the laparoscopic group (M (IQR)): (20 (110) ml vs. 40 (80) ml, Z=-4.098, P<0.01). The operation time ((111.7±33.6) minutes vs. (120.4±35.0) minutes, t=-0.943, P=0.350) and hospitalization time ((3.9±1.4) days vs. (4.7±1.9) days, t=-1.980, P=0.053) of the robot group and the laparoscopic group were similar. Follow-up for 12 months after the operation showed no postoperative complications and recurrence. The score of the health-related quality of life questionnaire for gastroesophageal reflux disease in the robot group decreased from 10.8±2.8 before the operation to 6.5±0.6 after the operation, and that in the laparoscopic group decreased from 10.6±2.1 before the operation to 6.3±0.6 after the operation. There was no difference in the influence of different surgical methods on the change in score (t=0.030,P=0.976). Conclusion: Compared with laparoscopic repair of the hiatal hernia, robot-assisted hiatal hernia repair has the advantages of less bleeding, rapid postoperative recovery and good short-term effect.

Diagnosis, prevention and treatment of post-operative rare complications after radical gastrectomy for gastric cancer / 中华胃肠外科杂志

Radical gastrectomy for gastric cancer results in various post-operative complications, and the influencing factors are complicated. The diagnosis, treatment and prevention of common complications have been reported in many literatures. However, there are few reports on the prevention and treatment of rare complications. Rare complications after radical gastrectomy are often overlooked due to their low incidence. In addition, there are few guidelines and expert consensus regarding to the rare complications. Therefore, clinicians may lack experience in the diagnosis, treatment and prevention of rare complications after radical gastrectomy. Based on the literature review and the author's experience, this article systematically reviews seven rare complications after radical gastrectomy (duodenal stump fistula, pancreatic fistula, chyle leakage, esophagomediastinal fistula, internal hernia, gastroparesis, and intussusception). This article aims to provide a comprehensive reference for the diagnosis, treatment and prevention of rare complications after radical gastrectomy for gastric cancer patients.

Treatment of obstructive colorectal cancer / 中华胃肠外科杂志

Obstructive colorectal cancer is a common malignant bowel obstruction. Colostomy or colostomy following tumor resection may be the first choice for emergency surgery. The intestinal and systemic conditions of patients undergoing emergency surgery are often poor, and patients need to undergo multiple operations, which increase the surgical risk and economic burden and reduce the quality of life of patients. Poor intraoperative visualization may also affect the radical operation of emergency surgery. Transanal decompression tube (TDT) can rapidly decompress and drain the obstructed bowel, effectively relieve obstruction symptoms, and improve the success rate of primary radical resection. The TDT squeeze the tumor lightly, causing no spread of tumor cells, and is cheap, but the cavity of transanal decompression tube is small and easily blocked, and requires tedious flushing or regular replacement. Self-expanding metallic stents (SEMS) can relieve intestinal obstruction effectively, provide sufficient preparation time for preoperative examination and improvement of nutritional status. By improving patient's tolerance to radical surgery, SEMS might be used as an important treatment strategy choice for obstructive colorectal cancer. However, SEMS may squeeze the tumor, leading to the spread of tumor cells, increase the recurrence rate and metastasis rate, and reduce the survival rate. Moreover, intestinal wall edema still existed during the operation following SEMS, and the rate of ostomy after anastomosis was as high as 34%. We hypothesized that prolonging the interval between stent insertion and surgery to 2 months, with neoadjuvant chemotherapy administered during this interval (SEMS-neoadjuvant chemotherapy strategy), would help improve outcomes. The SEMS-neoadjuvant chemotherapy strategy is a safe, effective, and well tolerated treatment approach with a high laparoscopic resection rate, low stoma formation rate and improvement in the overall survival for patients with left-sided colon cancer obstruction. The patient physical status is improved, the primary tumor is downstaged, and intestinal wall edema is relieved during the relatively longer interval between SEMS placement and surgery. The SEMS-neoadjuvant chemotherapy strategy may be a preferred therapeutic strategy for obstructive left colon cancer.

Conversion of osteoporotic-like vertebral fracture severity score to osteoporosis T-score equivalent status: A framework study for older Chinese men

Objectives@#To define what portion of older community men with what severity of radiographic osteoporotic-like vertebral fracture (OLVF) correspond to what low T-score status. @*Methods@#There were 755 community Chinese men (age: 76.4 ± 6.7 years) with thoracic and lumbar spine radiographs, and hip and lumbar spine bone mineral density measures. For each vertebra in a subject, a score of 0, -0.5, −1, −1.5, −2, −2.5, and −3 was assigned for no OLVF or OLVF of <20%, ≥ 20–25%, ≥ 2 5%–1/3, ≥ 1/3–40%, ≥ 40%–2/3, and ≥ 2/3 vertebral height loss, respectively. OLVFss was defined as the summed score of vertebrae T4 to L5. OLVFss and T-scores were ranked from the smallest to the largest values. @*Results@#OLVFss of −2, −2.5, −3, corresponded to a mean femoral neck T-score of −2.297 (range: -2.355∼-2.247), −2.494 (range: -2.637∼ −2.363), and −2.773 (range: -2.898∼-2.643), a mean hip T-score of-2.311 (range: -2.420∼-2.234), −2.572 (range: -2.708∼-2.432), −2.911 (range: -3.134∼-2.708), a mean lumbar spine T-score of −2.495 (range: -2.656∼-2.403), −2.931 (range: -3.255∼-2.664), and −3.369 (range: -3.525∼-3.258). The Pearson correlation value of OLVFss and T-score of femoral neck, hip and lumbar spine was r = 0.21, 0.26, and 0.22 (all P < 0.0001). @*Conclusions@#A single severe grade radiological OLVF (≥ 40% height loss) or OLVFss ≤ −2.5 suggest the subject is osteoporotic, and a single collapse grade (≥ 2/3 height loss) OLVF or OLVFss ≤ −3 meets osteoporosis diagnosis criterion. The results highlight the difficulty of diagnosing osteoporotic vertebral fractures among Chinese older men.

Radiological features of traumatic vertebral endplate fracture: an analysis of 194 cases with 263 vertebral fractures / 中华医学杂志(英文版)

BACKGROUND@#The importance of identifying osteoporotic vertebral endplate or/and cortex fracture (ECF), which primarily includes endplate fracture (EPF) and vertebral anterior cortex buckling, has been recognized. However, some old traumatic ECFs with healing process in the elderly may be mistaken as osteoporotic. This study analyzes the radiological features of traumatic EPF.@*METHODS@#This was a retrospective analysis of 194 spine trauma patients with 263 vertebral fractures (mean age: 42.11 ± 9.82 years, 118 males and 76 females). All patients had traumatic EPF identified by X-ray/CT/MRI.@*RESULTS@#The involved vertebra was mostly L1 (29.7%), followed by T12 and L2. Except EPFs involved both superior and inferior endplates (12.6%), only 1.9% involved inferior endplate alone, with the majority involved superior endplate. If each endplate was divided into five segments of equal lengths (from anterior to posterior: a1, a2, m, p2, p1), the most depressed point of superior EPFs was mostly at segment-a2 (approximately 45%), followed by segment-a1 (approximately 20%) or segment-m (approximately 20%), and very rarely at segment-p1. The upper 1/3 of anterior vertebral wall was more likely to fracture, followed by middle 1/3 of anterior wall. For posterior vertebral wall fracture, 68.5% broke the bony wall surrounding the basivertebral vain. 58.6%, 30.0%, and 11.4% of vertebral fractures had 1/3 vertebral body height loss. As the extent of vertebral height loss increased, the chance of having both superior and inferior EPFs also increased; however, the chance of having inferior EPF alone did not increase.@*CONCLUSION@#Traumatic EPF features are characterized, which may help the differentiation of traumatic and osteoporotic EPFs.

Analysis of efficiency of sacral neuromodulation in the treatment of non-neurogenic and non-obstructive dysuria in elderly patients / 中华老年医学杂志

Objective To evaluate the effectiveness and safety of sacral neuromodulation(SNM) in the treatment of non-neurogenic and non-obstructive dysuria in elderly patients.Methods Six elderly patients with non-neurogenic and non-obstructive(2 males and 4 females)treated with SNM were recruited from multiple medical centers across the country in this retrospective study from January 2012 to December 2016.All patients received two or more conservative treatments including behavior therapy,oral therapy,etc.,with no good effect.Data of the average residual urine volume,average urine volume,maximum urine volume,average urinary frequency and quality of life score before operation,after implantation of stage Ⅰ tined lead,and at the end of follow-up after implantation of stage Ⅱ implanted pulse generator(IPG) were compared.Results The average age in the 6 patients was 69.5 (65 ～ 79) years.The results of SNM treatment showed that the objective findings and/or subjective symptoms in all patients were significantly improved in more than 50％ of indexes before treatment.All patients chose embedding of IPG at the end of stage Ⅰ,with 100.0％ of the conversion rate from stage Ⅰ to stage Ⅱ.The curative effect was stable in general.At stages of baseline,personal experience and end of follow-up respectively,the average residual urine volumes were (161.7±110.2)ml,(70.0±52.2) ml,and(50.0±44.7)ml,the average urine volume were(105.0± 74.0)ml,(163.3 ± 93.1) ml,and (155.0 ± 92.3) ml,and the maximum urine volume were (146.7 ± 81.2) ml,(216.7 ± 93.1) ml,and (206.7 ± 112.7) ml,which showed continuously significant improvements with patients' great satisfaction.The mean duration of fellow-up in 6 cases was 17.5 months(7-57 months).No severe adverse reactions such as wound infection,electrode dislocation and hematoma were observed.Conclusions SNM treatment is safe and effective for elderly patients with non-neurogenic and non-obstructive dysuria who are refractory to other treatments.SNM has a stable medium-term curative effect and a high-transfer-rate from stage Ⅰ to stage Ⅱ,which is appropriate for non-neurogenic and non-obstructive dysuria.The duration of SNM may be positively correlated with the improvement of residual urine volume and urination frequency.

Cryoballoon Ablation for Atrial Fibrillation: a Comprehensive Review and Practice Guide

The cryoballoon was invented to achieve circumferential pulmonary vein isolation more efficiently to compliment the shortcomings of point-by-point ablation by radiofrequency ablation (RFA). Its efficacy and safety were shown to be comparable to those of RFA, and the clinical outcomes have improved with the second-generation cryoballoon. The basic biophysics, implemental techniques, procedural recommendations, clinical outcomes, and complications of the cryoballoon are presented in this practical and systematic review.

Cryoballoon Ablation for Atrial Fibrillation: a Comprehensive Review and Practice Guide

The cryoballoon was invented to achieve circumferential pulmonary vein isolation more efficiently to compliment the shortcomings of point-by-point ablation by radiofrequency ablation (RFA). Its efficacy and safety were shown to be comparable to those of RFA, and the clinical outcomes have improved with the second-generation cryoballoon. The basic biophysics, implemental techniques, procedural recommendations, clinical outcomes, and complications of the cryoballoon are presented in this practical and systematic review.

Pre-treatment with rapamycin protects hematopoiesis against radiation injury

Background: Protection of hematopoietic system has become a primary goal in the development of novel medical countermeasures against ionization radiation and radiotherapy. This study was to explore the role of rapamycin in normal tissues against radiation

Materials and Methods: Mice were pretreated with rapamycin by i.p. every other day for five times before 5 Gy or 8.5 Gy gamma-ray whole body irradiation. Blood cell counts, HE staining of bone marrow and liver, bone marrow transplantation, CFU of spleen were used to measure the damage of hematopoiesis and extramedullary hemopoietic organs. Regular karyotype analysis and expression of gamma-H2AX [by flow cytometry and western blot] were used to measure DNA damage. Rad 50 and DNA Lig 4 expression by western blot were to see the DNA repair ability

Results: The decrease of red blood cells and platelet induced by radiation were alleviated by pretreatment with rapamycin [d 7,15, p<0.01], and the long-term restoration of white blood cells, lymphocytes and bone marrow were enhanced in rapamycin pretreatment group [d 30,40,70, p<0.05]. The transplantation experiment also indicates that the long-term reconstitution in lethally irradiated recipient mice was improved in rapamycin group [p<0.05]. The hepatocellular injury by radiation was also reduced and the colony formation numbers of spleen after irradiation was improved in rapamycin group [p<0.05]. Karyotype analysis indicates that rapamycin protected bone marrow cells from chromosome mutation. Furthermore, expression of DNA repair proteins Rad 50 and DNA Lig 4 was enhanced and DNA damage marker gamma-H2AX was reduced in mice exposed to radiation by rapamycin pretreatment

Conclusion: Rapamycin pretreatment mitigates hematopoietic system from radiation injury in both bone marrow and extramedullary hematopoietic organs by improving genomic stability and increasing survival of hematopoietic stem and progenitor cells [HSPCs]

Clinical target volume [CTV] in postoperation radiotherapy of esophageal squamous cell carcinoma could benefit from the detection of telomere length in lymph node

Background: This study evaluated the relation between telomere length in lymph node [LN] and prognosis of esophageal squamous cell carcinoma [ESCC]

Materials and Methods: LNs collected from 50 patients were assessed by pathological examination and quantitative reverse transcription polymerase chain reaction [qRT-PCR], which was used for detecting telomere length. The relation between clinical factors and the number of lymph node metastasis [LNM] identified were analyzed by the x2 test. The comparison of the pattern of LNM identified by pathological examination and detection of telomere length was assessed by Wilcoxon signed-rank test. Overall survival was assessed using the Kaplan-Meier method, and Cox proportional hazard regression analysis was used to evaluate the relationship between survival and the number of LNM

Results: The best threshold values, which could define the positive metastasis by detecting the telomere length, were 1.50, using the critical value method of statistic. Length of tumor, depth of tumor invasion and differentiation of tumor correlated closely with LNM were identified by detecting telomere length. The rates of LNM identified by detecting telomere length were 34.4%, 22.4%, 22.9%, 5.0% in 108,107, 7, and 3 LN station, respectively. The number of LNM identified by detecting telomere length was more closely related to the prognosis of ESCC than that of pathological examination [HR: 1.23 VERSUS 1.04]

Conclusion: The change of telomere length in LN was closely related to the prognosis of ESCC. Delineation of clinical target volume [CTV] may benefit from the detection of telomere length in regional LN

Long-term effect of iodine deficiency on growth and food utilization rate in second filial generation rats / 中华预防医学杂志

To study the effect of iodine deficiency on body weight, food consumption, and food utilization rate of second filial generation Wistar rats.According to the food pattern of a high-iodine deficient population, two types of low-iodine food have been produced using the main crops grown in this area (iodine levels of 50 and 20 μg/kg, respectively). Wistar rats were randomly divided into three groups, normal iodine group (NI group), low-iodine group one (LI group) and low-iodine group two (LII group), using the random number table method and fed diets containing 300, 50, and 20 μg/kg of iodine, respectively. Parental generation rats were fed until they reached reproductive age; first filial generation rats were allocated to the same diet as their mothers. After 3 months of feeding, first filial generation rats gave birth to second filial generation rats; second filial generation rats were allocated to the same diet as their mothers. After feeding for 90, 180, and 270 days, rats were sacrificed. One-way analysis of variance was used to analyze body weight, food intake, and food utilization rate data collected during the time of feeding and blood iodine hormone level, which was determined after sacrifice.The LI and LII groups generally demonstrated decreased activity, slow reaction, and growth retardation compared with the NI group. After 270 days, the urine iodine levels of the LI and LII groups were 1.7 and 0.2 μg/L, respectively, which were significantly lower than the NI group (255.2 μg/L) (0.001). Additionally, the weight of female rats in the LI and LII groups were (288.1±10.5) and (275.7±2.7) g, respectively, which was significantly lower than that of the NI group ((311.0±2.3) g) (0.001). The weight of male rats were (446.0±4.6) and (451.8±19.1) g, respectively, which were significantly lower than that of the NI group ((517.2±7.8) g) (0.001). In the LI and LII groups, food intake of female and male rats after 270 days were (465.0±27.7), (658.4±28.6) and (423.0±13.2), (548.0±18.8) g, respectively, which were significantly lower than that of the NI group ((499.5±21.8), (760.8±33.0) g) (0.001). Moreover, the food utilization rate of female rats in the LI and LII groups was (8.7±0.4)% and (6.0±0.58)%, which was lower than that of the NI group ((11.7±3.5)%) (0.001); similarly, male rats showed rates of (8.9±1.5)% and (6.9±1.31)%, respectively, which were lower than that of the NI group ((13.7±3.0)%) (0.001). After 270 days, the level of T3 in the LI and LII groups were (0.45±0.10) and (0.34±0.15) ng/ml, respectively, which was significantly lower than that of the NI group ((0.91±0.49) ng/ml) (0.01). Moreover, the level of T4 were (69.02±27.87) , (53.18±13.53) ng/ml in LI and LII groups, respectively, which was lower than that of the NI group ((76.69±29.42) ng/ml) (0.05).This study indicated that iodine deficiency induced by a long-term low-iodine diet can cause changes in weight, food intake, and food utilization rate among second filial iodine deficiency rats. More importantly, the iodine content in low-iodine food impacts these parameters.

Rapid Increase in Marrow Fat Content and Decrease in Marrow Perfusion in Lumbar Vertebra Following Bilateral Oophorectomy: An MR Imaging-Based Prospective Longitudinal Study

OBJECTIVE: Bilateral oophorectomy leads to reduced bone mineral density (BMD), and reduced BMD is associated with increased marrow fat and reduced marrow perfusion. Purpose of this study was to investigate how soon these changes occur following surgical oophorectomy. MATERIALS AND METHODS: Six patients who underwent hysterectomy and bilateral salpingo-oophorectomy were studied. At baseline, mean patient age was 49.5 years (range: 45-54 years). Third lumbar vertebral body BMD measurement using quantitative CT, marrow fat fraction (FF) using MR spectroscopy and marrow perfusion using dynamic contrast enhanced MRI were conducted immediately prior to surgery and at 3, 9, and 21 months after surgery. RESULTS: Reduced BMD, increased marrow FF, and reduced marrow perfusion occurred synchronously post-oophorectomy. There was a sharp decrease of 12.5 +/- 7.2% in BMD (n = 6), a sharp increase of 92.2 +/- 46.3% (n = 6) in FF, a sharp decrease of 23.6 +/- 3.9% in maximum contrast enhancement (n = 5), and of 45.4 +/- 7.7% for enhancement slope (n = 5) during the initial 3 months post surgery. BMD and marrow perfusion continued to decrease, and marrow FF continued to increase at a slower rate during the following 18 months. Friedman test showed a significant trend for these changes (p < 0.05). CONCLUSION: Bilateral oophorectomy leads to a rapid decrease in lumbar BMD, an increase in marrow fat content, and a decrease in marrow blood perfusion.

Hepatic Sinusoidal Obstruction Syndrome Caused by Herbal Medicine: CT and MRI Features

OBJECTIVE: To describe the CT and MRI features of hepatic sinusoidal obstruction syndrome (HSOS) caused by herbal medicine Gynura segetum. MATERIALS AND METHODS: The CT and MRI features of 16 consecutive Gynura segetum induced HSOS cases (12 men, 4 women) were analyzed. Eight patients had CT; three patients had MRI, and the remaining five patients had both CT and MRI examinations. Based on their clinical presentations and outcomes, the patients were classified into three categories: mild, moderate, and severe. The severity of the disease was also evaluated radiologically based on the abnormal hepatic patchy enhancement in post-contrast CT or MRI images. RESULTS: Ascites, patchy liver enhancement, and main right hepatic vein narrowing or occlusion were present in all 16 cases. Hepatomegaly and gallbladder wall thickening were present in 14 cases (87.5%, 14/16). Periportal high intensity on T2-weighted images was present in 6 cases (75%, 6/8). Normal liver parenchymal enhancement surrounding the main hepatic vein forming a clover-like sign was observed in 4 cases (25%, 4/16). The extent of patchy liver enhancement was statistically associated with clinical severity classification (kappa = 0.565). CONCLUSION: Ascites, patchy liver enhancement, and the main hepatic veins narrowing were the most frequent signs of herbal medicine induced HSOS. The grade of abnormal patchy liver enhancement was associated with the clinical severity.

Experimental Evaluation of Accelerated T1rho Relaxation Quantification in Human Liver Using Limited Spin-Lock Times

OBJECTIVE: It was reported lately that to obtain consistent liver T1rho measurement, at 3T MRI using six spin-lock times (SLTs), is feasible. In this study, the feasibility of using three or two SLT points to measure liver T1rho relaxation time was explored. MATERIALS AND METHODS: Seventeen healthy volunteers underwent 36 examinations. Three representative axial slices were selected to cut through the upper, middle, and lower liver. A rotary echo spin-lock pulse was implemented in a 2D fast field echo sequence. Spin-lock frequency was 500 Hz and the spin-lock times of 1, 10, 20, 30, 40, and 50 milliseconds (ms) were used for T1rho mapping. T1rho maps were constructed by using all 6 SLT points, three SLT points of 1, 20, and 50 ms, or two SLTs of 1 and 50 ms, respectively. Intra-class correlation coefficient (ICC) and Bland and Altman plot were used to assess the measurement agreement. RESULTS: Two examinations were excluded, due to motion artifact at the SLT of 50 ms. With the remaining 34 examinations, the ICC for 6-SLT vs. 3-SLT T1rho measurements was 0.922, while the ICC for 6-SLT vs. 2-SLT T1rho measurement was 0.756. The Bland and Altman analysis showed a mean difference of 0.19 (95% limits of agreement: -1.34, 1.73) for 6-SLT vs. 3-SLT T1rho measurement, and the mean difference of 0.89 (95% limits of agreement: -1.67, 3.45) for 6-SLT vs. 2-SLT T1rho measurement. The scan re-scan reproducibility ICC (n = 11 subjects) was 0.755, 0.727, and 0.528 for 6-SLT measurement, 3-SLT measurement, and 2-SLT measurement, respectively. CONCLUSION: Adopting 3 SLTs of 1, 20, and 50 ms can be an acceptable alternative for the liver T1rho measurement, while 2 SLTs of 1 and 50 ms do not provide reliable measurement.

Determination of retardation effect of SOM on aqueous leaching of poly cyclic aromatic hydrocarbons using confocal laser scanning microscope

Influence of soil organic matter [SOM] on the adsorption, desorption and transport of polycyclic aromatic hydrocarbons [PAHs] has already been given full investigation in soils. In this paper, confocal laser scanning microscope [CLSM] was used to elucidate aqueous leaching of PAHs in different types of soil with soil columns, which enhanced understanding on transport of PAHs appreciably. Four typical soils in China including fluvo-aquic soil [FAS], aquic brown soil [ABS], red soil [RS] and black soil [BS] were selected in the experiment. Target pollutants of phenanthrene and pyrene were extracted from the leachate by solid phase extraction [SPE] and then determined by high performance liquid chromatography [HPLC]. The experimental results showed that the retardation ability of pollutants to the four selected types of soil increased in the order: FAS H" ABS < RS < BS. To better expatiate the dissimilar ability of the PAHs transported in the four typical soils, the retardation factor [R], distribution constant [K[d]] and partition coefficient [K[oc] were evaluated based on the observed breakthrough curves [BTCs]. Furthermore, CLSM was used to visualize the effects of SOM on the transport ability of PAHs in different types of soil. All the results provided vivid understanding with mathematical and especially optical measures that SOM was considered the single most important factor limiting the availability and mobility of PAHs in soil over the duration of the experiment

Effect of aging on bioavailability of copper on the fluvo aquic soil

The bioavailability of copper in contaminated soils has received more attention due to the safety concern of food chain. The bioavailability of metals is determined by its fractions which are affected by the soil properties and its aging time. This paper focused on the aging effect on the bioavailability of copper added to the soil. The garden soil [fluvo aquic soil] was treated with 100mg/kg and 1000 mg/kg of CuSO4 and incubated for 14, 21, 28, 42, 63, 120, 200, 300 and 400 days in the laboratory respectively. The sequential extraction procedure was used to characterize copper bioavailability in the soil. Meanwhile, the barley was cultured on the same soil incubated and its toxicity was assessed according to the guideline of International Organization for Standardization. The findings show that the exchangeable and carbonate-bound copper decreased with the aging time after addition of CuSO4 in to soil. Meanwhile, the percentages of Fe-Mn oxides and organic bound copper increased. The residual copper was changed little during the aging course. The copper fractions became stable in soils after 60 days. The kinetic equations showed that the Power function and the Elovich equation were fitted well to the experimental data, and the r2 values ranged from 0.840 to 0.982 and 0.741 to 0.975 respectively. The barley test showed that the barley root length was more sensitive to reflect copper toxicity than the shoot biomass. And the exchangeable and carbonate-bound copper were significantly correlated with the barley root length

Forecast of water level and ice jam thickness using the back propagation neural network and support vector machine methods

Ice jams can sometimes occur in high latitude rivers during winter and the resulting water level rise may generate costly and dangerous flooding such as the recent ice jam flooding in the Nechako River in downtown Prince George in Canada. Thus, the forecast of water level and ice jam thickness is of great importance. This study compares three methods to simulate and forecast water level and ice jam thickness based on field observations of river ice jams in the Quyu Reach of the Yellow River in China. More specifically, simulation results generated by the traditional multi-variant regressional method are compared to those of the back propagation neural network and the support vector machine methods. The forecast of ice jam thickness and water level under ice jammed condition have been conducted in two different approaches, 1] simulation of water level and ice jam thickness in the second half of the period of measurement using models developed based on data gained during the first half of the period of measurement, 2] simulation of water level and ice jam thickness at the downstream cross sections using models developed based on data gained at the upstream cross sections. For this reason, as the results of simulation and field observations indicated, the back propagation neural network method and the support vector machine method are superior in terms of accuracy to the multi-variant regressional method

Demographic, laboratory and clinical characteristics of HIV-positive tuberculosis cases in Canada

Human immunodeficiency virus [HIV] is an important risk factor for the global incidence and mortality of tuberculosis [TB] and has had a tremendous impact on the epidemiology and the control of the disease. The purpose of this study was to determine the demographic, laboratory and clinical characteristics of HIV-positive TB cases in Canada as compared to HIV-negative cases. TB cases reported to the Canadian TB Reporting System [CTBRS] from 1997 to 2006 were retrospectively reviewed and for those with known HIV serostatus, the distributions of age, sex, country of birth, smear and culture positivity, drug resistance, site of disease and treatment outcome were compared. 2710 TB cases had a report of an HIV test with a 12.9% positivity rate. HIV-positive cases were more likely to be 30-44 years old, male, Canadian born non-Aboriginal or African born. Sputum and lymph node biopsies were significantly more likely to be smear-positive and sputum was more likely to be culture positive. Anti-TB drug resistant rates were similar, except for lower streptomycin resistance in new HIV-positive cases. HIV-positive cases were significantly more likely to present with miliary or central nervous system TB, to have multi-system disease, to have lower treatment success rates [66.4% versus 88.5%] and to have a 5.6 higher case-fatality rate. HIV-positive cases have a different demographic profile, present with more advanced and severe forms of disease, have poorer treatment outcomes and higher mortality. All TB cases should be tested for HIV so as to offer appropriate case management and treatment

Numerical simulations of ice accumulation under ice cover along a river bend

In this paper, the k-epsilon two-equation turbulence model has been used to simulate ice accumulation under ice cover along a river bend. A 2D depth-averaged numerical model has been developed in a nonorthogonal coordinate system with nonstaggered curvilinear grids. In this model, the contravariant velocity has been treated as an independent variable. To avoid the pressure oscillation in the nonstaggered grids, the momentum interpolation has been introduced to interpolate variables at the interface. The discretization equations have been solved by using pressure correction algorithms. An equation has been developed for describing the deformation of ice jam bottom. The thickness distribution of ice accumulation [ice jam] along the bend has been simulated. The developed model has been applied to the experimental studies under different conditions carried out at the Hefei University of Technology. Results indicate that all simulated thickness of ice accumulation agrees reasonably well with the measured thickness of ice accumulation in laboratory