Lower subcutaneous fat index predicts bone metastasis in breast cancer.

BACKGROUND: Bone metastases affect 50% to 70% of breast cancer (BC) patients and have a high mortality rate. Adipose tissue loss plays a pivotal role in the progression of cancer. OBJECTIVE: This study aims to evaluate the prognostic value of adipose tissue for bone metastasis in BC patients. METHODS: 517 BC patients were studied retrospectively. Patients' characteristics before the surgery were collected. Quantitative measurements of the subcutaneous fat index (SFI) were performed at the level of the eleventh thoracic vertebra. In order to adjust for the heterogeneity between the low SFI and high SFI groups, propensity score matching (PSM) was used. The Kaplan-Meier method was used to estimate the 5-year bone metastatic incidence. The prognostic analysis was performed with the Cox regression models. RESULTS: Compared with the patients without bone metastasis, the patients with bone metastasis had reduced SFI levels. In addition, Kaplan-Meier analysis revealed that patients with low SFI were more likely to develop bone metastases. The independent predictive value of SFI for bone metastases was confirmed by Cox regression analysis. The survival analysis was repeated after PSM with a 1:1 ratio, yielding similar results (P< 0.05). CONCLUSIONS: SFI is an independent predictor of bone metastasis in BC patients.

Utility of mean platelet volume in differentiating intrahepatic cholangiocarcinoma from hepatocellular carcinoma.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC) are the most prevalent histologic types of primary liver cancer. HCC and ICC differ in treatment and prognosis, warranting an effective differential diagnosis between them. This study aimed to explore the clinical value of mean platelet volume (MPV) to discriminate between HCC and ICC. MATERIAL/METHODS: We performed a retrospective analysis of ICC and HCC patients who were from the Harbin Medical University Cancer Hospital, China. Logistic regression analysis was used to identify the independent factors for the differentiation of HCC and ICC. A receiver operating characteristic curve was built to evaluate the diagnostic performance of the potential model. An independent validation study was performed to validate the diagnostic ability. RESULTS: ICC patients were detected in 146 out of 348 patients in the primary cohort. MPV levels were decreased in ICC patients compared with those in HCC patients. Logistic regression analysis revealed that MPV was an independent factor in distinguishing HCC from ICC. A combination of sex, hepatitis B surface antigen, MPV, alpha-fetoprotein, and carbohydrate antigen 19-9 demonstrated a good capability to differentiate HCC from ICC. Similar results were achieved in the validation cohort. CONCLUSIONS: MPV may be a new marker to help distinguish ICC from HCC. Further validation studies are required.

Preoperative PDW levels predict pulmonary metastasis in patients with hepatocellular carcinoma.

BACKGROUND: In hepatocellular carcinoma (HCC), pulmonary metastasis (PM) after hepatectomy is associated with poor clinical outcomes. The crucial phases of tumour cell proliferation, angiogenesis, and metastasis all entail platelet activation. In HCC, platelet distribution width (PDW) suggests platelet size changes and predicts a worse prognosis. The aim of this study was to assess the association between PDW and PMs in HCC patients receiving hepatectomy. MATERIAL/METHODS: From January 2013 to December 2015, a cohort of patients who underwent hepatectomy for HCC at the Harbin Medical University Cancer Hospital in China were retrospectively evaluated. The relationship between PDW levels and clinical and demographic parameters was examined. To investigate the relationships between predicted factors and PM, a competing risk model was used. From January 2016 to December 2018, a validation cohort of 109 patients from the First Affiliated Hospital of Harbin Medical University was studied independently. RESULTS: In the primary cohort, 19 out of 214 patients had postoperative PMs. In HCC patients with PM, PDW levels were lower than in those without PM. There was a significant difference in the cumulative incidence of 2-year PM between the high-PDW and low-PDW groups after controlling for competing risk events (death prior to the development of PM) (p < 0.001). In addition, PDW was also found to be an independent predictor for PM in a multivariable competing risk analysis. The results were externally validated in another cohort. CONCLUSIONS: In HCC, preoperative PDW is significantly associated with PM. PDW could be a biomarker for post-operative PM in HCC patients.

Preoperative Pectoralis Muscle Index Predicts Distant Metastasis-Free Survival in Breast Cancer Patients.

Background: Breast cancer is one of the most commonly diagnosed cancers, and the fourth leading cause of cancer deaths in females worldwide. Sarcopenia is related to adverse clinical outcomes in patients with malignancies. Muscle index is a key parameter in evaluating sarcopenia. However, there is no data investigating the association between muscle index and distant metastasis in breast cancer. The aim of this study was to explore whether muscle index can effectively predict distant metastasis and death outcomes in breast cancer patients. Study Design: The clinical data of 493 breast cancer patients at the Harbin Medical University Cancer Hospital between January 2014 and December 2015 were retrospectively analyzed. Quantitative measurements of pectoralis muscle area and skeletal muscle area were performed at the level of the fourth thoracic vertebra (T4) and the eleventh thoracic vertebra (T11) of the chest computed tomography image, respectively. The pectoralis muscle index (PMI) and skeletal muscle index (SMI) were assessed by the normalized muscle area (area/the square of height). Survival analysis was performed using the log-rank test and Cox proportional hazards regression analysis. Result: The patients with metastases had lower PMI at T4 level (PMI/T4) and SMI at T11 level (SMI/T11) compared with the patients without metastases. Moreover, there were significant correlations between PMI/T4 and lymphovascular invasion, Ki67 expression, multifocal disease, and molecular subtype. In addition, multivariate analysis revealed that PMI/T4, not SMI/T11, was an independent prognostic factor for distant metastasis-free survival (DMFS) and overall survival (OS) in breast cancer patients. Conclusions: Low PMI/T4 is associated with worse DMFS and OS in breast cancer patients. Future prospective studies are needed.

Transcription factor Klf9 controls bile acid reabsorption and enterohepatic circulation in mice via promoting intestinal Asbt expression.

Bile acid (BA) homeostasis is regulated by the extensive cross-talk between liver and intestine. Many bile-acid-activated signaling pathways have become attractive therapeutic targets for the treatment of metabolic disorders. In this study we investigated the regulatory mechanisms of BA in the intestine. We showed that the BA levels in the gallbladder and faeces were significantly increased, whereas serum BA levels decreased in systemic Krüppel-like factor 9 (Klf9) deficiency (Klf9-/-) mice. These phenotypes were also observed in the intestine-specific Klf9-deleted (Klf9vil-/-) mice. In contrast, BA levels in the gallbladder and faeces were reduced, whereas BA levels in the serum were increased in intestinal Klf9 transgenic (Klf9Rosa26+/+) mice. By using a combination of biochemical, molecular and functional assays, we revealed that Klf9 promoted the expression of apical sodium-dependent bile acid transporter (Asbt) in the terminal ileum to enhance BA absorption in the intestine. Reabsorbed BA affected liver BA synthetic enzymes by regulating Fgf15 expression. This study has identified a previously neglected transcriptional pathway that regulates BA homeostasis.

Significant difference of c-type lectin-like receptor 2 between colorectal cancer and polyp subgroups.

BACKGROUND: Platelets play a key role in tumor progression and metastasis. C-type lectin-like receptor 2 (CLEC-2) is the receptor expressed on platelets and the marker of platelet activation. OBJECTIVE: This study aims to determine whether soluble CLEC-2 levels differ between patients with benign colorectal polyps and those with colorectal cancer (CRC). METHODS: We measured plasma soluble CLEC-2 by enzyme-linked immunosorbent assay in 150 patients with colorectal polyps, 150 CRC patients without metastasis, 150 CRC liver metastasis, and 150 control subjects. RESULTS: The CRC patients had higher soluble CLEC-2 levels than patients with colorectal polyps (p< 0.001). Moreover, CRC patients with liver metastases displayed higher CLEC-2 levels than those in CRC patients without metastases (p< 0.001). In the CRC patients, CLEC-2 levels were correlated with lymph node metastasis and advanced stage. In the patients with polyps, there was a significant difference in CLEC-2 levels among patients with hyperplastic polyp, sessile serrated adenoma, and traditional serrated adenoma (p< 0.001). The ROC curve analysis revealed CLEC-2 had an optimal sensitivity of 77.3% and specificity of 94.6% for the screening of CRC, and sensitivity of 71.0% and specificity of 76.7% for the differential diagnosis of colorectal polyps and CRC. CONCLUSIONS: CRC patients have higher CLEC-2 levels than patients with colorectal polyps and healthy controls. Moreover, there is a significant difference in CLEC-2 levels among polyp subtypes. Further research is warranted.

Association between apoptosis inhibitor of macrophage and microsatellite instability status in colorectal cancer.

BACKGROUND: The microsatellite instability (MSI) in colorectal cancer (CRC) has a more favorable clinical outcome and is characterized by highly upregulated expression of various immunological checkpoints than microsatellite stable (MSS) tumors. Apoptosis inhibitor of macrophage (AIM) is a circulating protein and circulates throughout the body to remove cellular debris. The aim of this study was to evaluate the association between MSI status and AIM levels in CRC patients. METHODS: In this study, we evaluated the levels of AIM by Enzyme Linked Immuno-Sorbent Assay (ELISA) in serum of 430 CRC patients. All patients' clinical and laboratory characteristics at initial diagnosis were collected. The relationship between AIM levels and MSI status was examined. RESULTS: 64 patients (14.9%) were identified as having MSI-H (high-frequency MSI) and 366 casess (85.1%) having MSS. Patients with an MSI-H phenotype had lower AIM levels compared with MSS patients. Moreover, AIM levels were correlated with histological type and MSI status. Logistic regression analysis revealed that decreased AIM levels were independently associated with MSI-H phenotype after adjusting confounding factors. CONCLUSION: Reduced AIM levels are associated with MSI-H subtyping of CRC. Further research on the involvement of AIM in MSI-H CRC is needed.

Higher platelet distribution width is associated with unfavorable prognosis in ovarian cancer.

BACKGROUND: Ovarian cancer (OC) is one of the most malignant gynecological cancers. Platelets play a profound role in cancer growth and metastasis. Platelet distribution width (PDW) is an indicator of platelet activation and is altered in malignancies. However, the prognostic value of PDW in OC remains unclear. This present study aimed to investigate the predictive significance of PDW in OC. METHODS: 221 OC patients, between January 2013 and December 2013, were included in this study. The correlations between PDW and clinicopathological features were analyzed. Kaplan-Meier method and Cox regression were used to evaluate the prognostic impact of PDW. RESULTS: Of the 221 patients, increased PDW levels were observed in 163 (73.6%) patients. Kaplan-Meier analysis revealed that higher PDW levels were associated with poor progression-free survival and overall survival (both p< 0.001). Cox-regression analysis confirmed the independent predictive value of PDW on overall survival (HR = 2.820, 95% CI = 1.776-4.476, p< 0.001). CONCLUSION: Higher PDW levels predict poor prognosis in patients with OC. Elevated PDW may be a novel target for therapy.

Involvement of galanin and galanin receptor 1 in nociceptive modulation in the central nucleus of amygdala in normal and neuropathic rats.

The present study was performed to explore the role of galanin and galanin receptor 1 (GalR 1) in nociceptive modulation in the central nucleus of amygdala (CeA) in normal rats and rats with neuropathy, and the involvement of GalR 1 and PKC was also investigated. The hindpaw withdrawal latencies (HWLs) to thermal and mechanical stimulations were increased in a dose-dependent manner after intra-CeA injection of galanin in both normal rats and rats with neuropathy. The increased HWLs were significantly attenuated by intra-CeA injection of galanin receptor antagonist M40, indicating an involvement of galanin receptor in nociceptive modulation in CeA. Furthermore, intra-CeA administration of the GalR 1 agonist M 617 induced increases in HWLs in normal rats, suggesting that GalR 1 may be involved in galanin-induce antinociception in CeA. Additionally, intra-CeA injection of the PKC inhibitor inhibited galanin-induced antinociception, showing an involvement of PKC in galanin-induced antinociception in CeA of normal rats. Moreover, there was a significant increase in GalR1 content in CeA in rats with neuropathy than that in normal rats. These results illustrated that galanin induced antinociception in CeA in normal rats and rats with neuropathy, and there is an up-regulation of GalR1 expression in rats with neuropathy.

Involvement of galanin and galanin receptor 2 in nociceptive modulation in anterior cingulate cortex of normal rats and rats with mononeuropathy.

The present study was performed to explore the role of galanin and galanin receptor 2 in nociceptive modulation in anterior cingulate cortex (ACC) of normal rats and rats with mononeuropathy. Intra-ACC injection of galanin induced significant increases in hindpaw withdrawal latencies (HWLs) to thermal and mechanical stimulations in both normal rats and rats with mononeuropathy, the increased HWLs were attenuated significantly by intra-ACC injection of galanin receptor 2 antagonist M871, indicating an involvement of galanin receptor 2 in nociceptive modulation in ACC. Interestingly, the galanin-induced HWL was significant higher in rats with mononeuropathy than that in normal rats tested by Randall Selitto test. Furthermore, both the galanin mRNA expression and galanin content increased significantly in ACC in rats with mononeuropathy than that in normal rats. Moreover, both the mRNA levels of galanin receptor 2 and the content of galanin receptor 2 in ACC increased significantly in rats with mononeuropathy than that in normal rats. These results found that galanin induced antinociception in ACC in both normal rats and rats with mononeuropathy. And there may be plastic changes in the expression of galanin and galanin receptor 2 in rats with mononeuropathy, as well as in the galanin-induced antinociception.

Antinociception induced by galanin in anterior cingulate cortex in rats with acute inflammation.

The present study was performed to explore the role of galanin in nociceptive modulation in anterior cingulate cortex (ACC) of rats with acute inflammation, and the changes in galanin and galanin receptor 2 (Gal R2) expressions in rats with acute inflammation. Intra-ACC injection of galanin induced antinociception in rats with acute inflammation, the antinociceptive effects induced by galanin were attenuated significantly by intra-ACC injection of the Gal R2 antagonist M871, indicating an involvement of Gal R2 in nociceptive modulation in ACC in rats with acute inflammation. Furthermore, we found that both the galanin mRNA expression and galanin content increased significantly in ACC in rats with acute inflammation than that in normal rats. Moreover, both the mRNA levels of Gal R2 and the content of Gal R2 in ACC increased significantly in rats with acute inflammation than that in normal rats. These results demonstrated that galanin induced antinociception in ACC in rats with acute inflammation. And there were changes in the expression of galanin and Gal R2 in rats with acute inflammation.

Involvement of galanin receptor 2 and CaMKII in galanin-induced antinociception in periaqueductal grey of rats.

The present study was performed to explore the effect of the galanin receptor 2 (GalR2) antagonist M871 on the galanin-induced antinociception in periaqueductal grey (PAG), and an involvement of Ca(2+)/calmodulin-dependent kinase II (CaMKII) in the galanin-induced antinociception. Intra-PAG injection of galanin induced marked increases in HWLs to noxious thermal and mechanical stimulation. The increased HWLs to thermal and mechanical stimulation decreased significantly after intra-PAG administration of the GalR2 antagonist M871, indicating an involvement of GalR2 in the galanin-induced antinociception in PAG of rats. Furthermore, rats received intra-PAG injection of galanin, followed 5min later by intra-PAG administration of the CaMKII inhibitor MAP. The galanin-induced increases in HWLs to thermal and mechanical stimulation decreased significantly after intra-PAG administration of MAP, indicating that there is an involvement of CaMKII in the galanin-induced antinociception in PAG, blockade the activity of CaMKII by MAP inhibits the galanin-induced antinociception in PAG of rats. Our results strongly indicate that the galanin-induced antinociception is mediated by GalR2 in the PAG, and CaMKII may be involved in the galanin-induced antinociception in PAG of rats.

[A survey on the agricultural profession-related injuries among 11 902 rural residents in Shandong province].

OBJECTIVE: To understand the prevalence and risk factors of agricultural activities related injuries among rural residents in Shandong province. METHODS: A retrospective investigation was conducted among agricultural profession-related workers in 20 villages with multistage cluster sampling method in Shandong province. Four times face-to-face interview were conducted by trained interviewers, including 32 students and local medical personnel under constructed questionnaires. Accidental injuries occurred in the activities or in the agricultural profession-related jobs were recorded, from May 1(st)2009 to April 30(st) 2010. Data was input and analyzed by SPSS 13.0 statistical software. RESULTS: A total of 837 cases reported at least 1 job-related injury out of the 11 902 people who had been surveyed in one year. The crude incidence rate was 7.03% and the standardized incidence rate was 7.36%, higher in males (9.01%) than in females (4.10%), χ² = 105.53, P = 0.000. Children and adolescents (≤ 14 aged) had the higher incidence rate (9.50%), χ² = 9.70, P = 0.008. People working in the area of commercial service related to agricultural products had the highest incidence rate (12.94%). In particular, those occupations that related to agricultural construction or materials appeared to have had higher incidence rates as 16.80% and 15.59% respectively, than other kinds of jobs (χ² = 167.30, P = 0.000). There were higher proportion of injuries occurred in the roads (28.79%), in the fields (28.08%)during labor work (38.00%) transportation (27.97%), respectively. The seasonality of agricultural injures mostly occurred between June and August, accounted for 47.43%. Major external causes related to injuries were instruments or tools (31.42%) being used, transportation (24.13%) and falls (20.19%). Wounds on limbs took the majority (56.39%). The accidental self-inflicted injury occupied 76.82%, while accidents to passive injuries occupied 11.47%, other kinds accounted for 11.71%. Most of the accidents caused mild or moderate damage, accounted for 60.22% and 30.34% respectively. 7 cases died of injuries, with the fatality rate as 0.84% and the mortality rate was 58.81 per one hundred thousand. 72 cases ended up in disability caused by injuries, with the morbidity rate as 6.05 per thousand. Answers to the major internal causes of injuries appeared to be: "did not know how to protect oneself" (29.87%) with females (45.41%) in particular, followed by"over fatigue" and "inappropriate treatment" which took the 2(nd) place in males. Major natural environmental factors of injuries would relate to "high air temperature and humidity but lower wind velocity" (14.93%), "unclear signs on the country road" (12.19%), "the sky was cloudy or dark" (10.87%), "slippery road caused by rain or snow" (10.51%), "kids were unintended" (10.27%) etc. Most of the wounded received treatment clinically (50.18%), with the percentile (P50) of medical cost as 182.76 RMB (Yuan). The proportion of inpatient was 27.72% and with percentile of time as P(50) = 7.57 day and cost as P(50) = 2840.00 RMB Yuan. The wounded had a rest of P50 = 5.9 days, with an indirect cost as P(50) = 233.16 RMB Yuan. CONCLUSION: The results of this study indicated that the incidence of agricultural profession-related injuries was high, with serious harm. Behavioral intervention and awareness of injuries should be enhanced, together with the improvement of environmental condition.

Determination of main components and anaerobic rumen digestibility of aquatic plants in vitro using near-infrared-reflectance spectroscopy.

A near-infrared-reflectance (NIR) spectroscopy-based method is established to determine the main components of aquatic plants as well as their anaerobic rumen biodegradability. The developed method is more rapid and accurate compared to the conventional chemical analysis and biodegradability tests. Moisture, volatile solid, Klason lignin and ash in entire aquatic plants could be accurately predicted using this method with coefficient of determination (r(2)) values of 0.952, 0.916, 0.939 and 0.950, respectively. In addition, the anaerobic rumen biodegradability of aquatic plants, represented as biogas and methane yields, could also be predicted well. The algorithm of continuous wavelet transform for the NIR spectral data pretreatment is able to greatly enhance the robustness and predictive ability of the NIR spectral analysis. These results indicate that NIR spectroscopy could be used to predict the main components of aquatic plants and their anaerobic biodegradability.

[Repeated gonadotropin stimulations lower the developmental potential of mouse oocytes].

OBJECTIVE: To assess the effect of repeated gonadotropic stimulations on the developmental potential and growth differentiation factor-9 (GDF-9) expression of mouse oocytes. METHODS: Female Kunming mice were treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) for 3 times, and the control mice were treated with normal saline. The two groups of mice were both stimulated subsequently to obtain the mature oocytes. Immunocytochemical staining was employed to evaluate GDF-9 expression in the oocytes. The oocytes were then inseminated and cultured till the formation of blastocysts to compare the cleavage rate and blastocyst formation rate between the groups. RESULTS: A total of 253 mature oocytes were obtained in the repeated stimulation group, with a mean of 11.5 oocytes from each mouse; 521 mature oocytes were obtained in the control group with a significantly greater mean number of 32.6 from each mouse (P<0.05). The average optical density and integrated optical density for GDF-9 expression were significantly lower in the oocytes in repeated stimulation group than in the control group (P<0.05 and 0.01, respectively). After insemination, the cleavage rate were comparable between repeated stimulation group and the control group (85.6% vs 88.8%), but the blastocyst formation rate was significantly lower in repeated stimulation group (20.8% vs 35.2%, P<0.01). CONCLUSION: Repeated gonadal stimulation decreases the developmental potential of mouse oocytes possibly due to reduced GDF-9 expression.

Rapid and accurate determination of VFAs and ethanol in the effluent of an anaerobic H(2)-producing bioreactor using near-infrared spectroscopy.

A rapid quantification method, based on Fourier transform near-infrared (FT-NIR) spectroscopy, was developed and validated to nondestructively quantify the concentrations of volatile fatty acids and ethanol in the effluent of an anaerobic H(2)-producing bioreactor. The first-derivative spectra calculated by a simple numerical difference, combined with the orthogonal signal correction method, were used as spectral preprocessing options. A calibration model was established and validated using gas chromatography measurement results. The number of internal latent variables was optimized based on the lowest root-mean-square error of calibration. The calibration model established shows the satisfactory results for the lowest root-mean-square errors of prediction compared to other preprocess methods. The method developed in this work is demonstrated to be more flexible compared with other approaches to determine the concentrations of volatile fatty acids and ethanol in the anaerobic reactor effluents.

Quantification of the interactions between a cationic dye and humic substances in aqueous solutions.

Humic substances (HS) are ubiquitous in natural waters. Due to their plentiful binding sites, HS play an important role in the mobilization and transport of pollutants in natural environments. However, the presence state of HS causes difficulty in exploring the interactions between HS and pollutants in aqueous solutions. In this study, an effective and rapid method was proposed to quantify the interaction between a cationic dye and HS in aqueous solutions. Humic acids (HA) and Toluidine Blue (TB) were respectively used as the model HS and model cationic dye. This characterization method was based on the binding of TB to HA molecule to form a TB-HA complex. From the difference between the visible spectra of the dye and the TB-HA complex, the adsorption capability of HA could be evaluated. Results demonstrate that the Langmuir adsorption isotherm theory was appropriate to describe the interaction between TB and HA. Both pH and ionic strength had significant effects on the adsorption of TB onto HA. These results suggest that the binding reaction was a physical adsorption driven by the electrostatic interaction.

Determination of proteins and carbohydrates in the effluents from wastewater treatment bioreactors using resonance light-scattering method.

A simple and sensitive method was developed for the determination of low-concentration proteins and carbohydrates in the effluents from biological wastewater treatment reactors using resonance light-scattering (RLS) technique. Two ionic dyes, Congo red and Neutral red were, respectively used as an RLS probes for the determination of proteins and carbohydrates. This method is based on the interactions between biomacromolecules and dyes, which cause a substantial increase in the resonance scattering signal of dyes in the wavelength range of 200-650 nm. The characteristics of RLS spectra of the macromolecule-dye complexes, influencing factors, and optimum analytical conditions for the measurement were explored. The method was satisfactorily applied to the measurement of proteins and carbohydrates in the effluents from 10 aerobic or anaerobic bioreactors, and a high sensitivity were achieved.

Characterization of adsorption properties of extracellular polymeric substances (EPS) extracted from sludge.

Extracellular polymeric substances (EPS) of sludge play an important role in the adsorption of organic pollutants in wastewater biological treatments. Experiments were conducted to characterize the adsorption properties of EPS extracted from aerobic sludge (AE-EPS) and anaerobic sludge (AN-EPS) using a dye-probing method in this study. A model cationic dye, Toluidine blue (TB), was used as the dye probe. The adsorption of dye onto EPS to produce a dye-EPS complex would cause a change in the solution absorbance, attributed to the difference between the visible spectra of the dye and dye-EPS complex. From the change in the absorbance, the equilibrium absorption capability of EPS could be evaluated. Results indicate that Langmuir adsorption isotherm was able to adequately describe the adsorption equilibrium of TB onto both EPS at various pH values. From the Langmuir adsorption isotherm, the maximum binding capabilities were calculated to be 1.9 and 2.5 mmol/g EPS for AE-EPS at pH 7.0 and 11.0, and 1.6 and 1.9 mmol/g EPS for AN-EPS at pH 7.0 and 11.0, respectively. The first-order rate constants were calculated to be 0.033 and 0.35 min(-1) for AE-EPS at pH 7.0 and 11.0, and 0.069 and 0.18 min(-1) for AN-EPS at pH 7.0 and 11.0, respectively. The results of the present study demonstrated that the dye-probing method was appropriate for investigating the adsorption process of EPS in aqueous solution.

A rapid quantitative method for humic substances determination in natural waters.

A simple and rapid method was proposed for humic substances (HS) determination at microgram levels in natural waters. This assay method is based on the binding of a dye, Toluidine Blue (TB), to HS molecules to produce a dye-HS complex, which causes a decrease in absorbance at 630 nm. This method was calibrated with HS samples with up to a concentration of 40 mg L(-1), which covered the range of dissolved HS concentrations present in natural waters. The detection limit was 0.8 mg L(-1) of HS, and the relative standard deviation of 10 replicate measurements for a 20-mg L(-1) standard sample was 3.5%. From the Langmuir adsorption isotherm theory, the binding equilibrium constant and total number of binding sites at neutral pH were calculated to be (8.17+/-0.42)x10(5) L mol(-1) and N of 1.45+/-0.04 mmol g(-1) HS, respectively. The determination results with five water samples from lake, river and pond were consistent with those measured with the reference methods, demonstrating that this quantification method for HS determination was rapid, sensitive and feasible.