Association between metabolic syndrome and vascular endothelium dysfunction in children and adolescents

We aimed at investigating the association between metabolic syndrome (MS) and vascular endothelial cell dysfunction (ECD) in children and adolescents. Sixty children (30 obese children and 30 children with MS) were included in this retrospective analysis. Thirty healthy subjects were randomly selected as the control group. A series of indices/biomarkers known to be related to MS/ECD were determined using ELISA. Correlations between the variables measured were analyzed. Compared with the control group, PAI-1, vWF, VE-cad, TM, and VEGF were significantly increased in the MS group (P < 0.05). Adolescents in the obese group had significantly increased levels of serum PAI-1, VE-cad, TM, and VEGF as compared with the control group (P < 0.05). Further, vWF in the obese and control groups did not differ significantly (P = 0.556). Our results suggest that ECD is correlated with MS in children and adolescents. Pathophysiological changes of the vascular endothelium may exist in obese children who have yet to develope MS. PAI-1, vWF, VE-cad, TM, and VEGF could be used as biomarkers for predicting ECD. ECD that develops in patients with MS may be associated with obesity, elevated blood lipid, elevated blood glucose, and higher blood pressure.

Effects of feeding lutein on production performance, antioxidative status, and milk quality of high-yielding dairy cows

This experiment was conducted to determine the influences of supplementing different levels of an additive containing lutein in the diet of Chinese Holstein lactating cows on production performance, antioxidative plasma metabolites, and milk quality. This study was performed on 60 multiparous Holstein dairy cows in peak lactation. The cows were randomly allocated to 1 of 4 homogeneous treatments, with lutein preparation (extracted from marigolds; effective lutein content was 2%) added at levels of 0, 100, 150, and 200 g/d per head, with the actual available amounts being 0, 2, 3, and 4 g of lutein/d per head, respectively. The experiment lasted for 13 wk, with the first week for adaptation. Milk yield and milk compositions were recorded weekly, and milk concentrations of lutein, dry matter intake, and antioxidative blood index were analyzed in the first, fourth, seventh, and thirteenth week of the study. The results showed that adding lutein in the diet had no effect on dry matter intake compared with the control group; however, it slowed down the trend of decline in milk yield, and had a linear incremental effect on milk yield with increasing concentration of lutein. Dietary lutein tended to quadratically increase the percentage of milk fat, and linearly increased milk lactose concentration, with the highest value when treated at 200 g of lutein preparation/d per head, and decreased somatic cell count, with the lowest values when treated with 150 and 200 g of lutein preparation/d per head. The concentration of lutein in milk linearly increased with the incorporation of the additive, with a value of 0.59, 0.70, 1.20, and 1.50 μg/100mL when treated with 0, 100, 150, and 200 g/d, respectively. Total plasma antioxidant capacity tended to linearly increase in cows fed lutein preparation, whereas plasma superoxide dismutase and glutathione peroxidase activities did not differ significantly. In conclusion, addition of lutein in the diet could improve the production performance and health status of dairy cows.

Immediate radical therapy or conservative treatments when meeting the Milan criteria for advanced HCC patients after successful TACE

BACKGROUND AND AIMS

Many advanced hepatocellular carcinoma (HCC) cases can be successfully downstaged into the Milan criteria; however, immediate radical therapy cannot be applied to all such patients for various reasons. Of the patients who are not eligible for immediate radical therapy, some accept repeated downstaging therapies and some undergo persistent observation. The aim of the present study was to compare long-term survival between these two groups of patients.

PATIENTS AND METHODS

Between August 2003 and October 2008, 156 HCC patients successfully received downstaging therapy resulting in compliance with the Milan criteria. Of those, 98 cases accepted radical therapies, including liver transplantation (LT), resection, or radiofrequency ablation (RFA) (group 1), and 58 cases underwent repeated transcatheter arterial chemoembolization (TACE) or persistent observation (group 2). The baseline characteristics, demographic data, downstaging protocol, and information on long-term outcomes were collected and compared.

RESULTS

No significant differences were observed in the patient demographic data, downstaging protocols, or tumor characteristics between the two groups. The 1-, 3-, and 5-year overall survival rates were 92.9, 82.7, and 78.6 %, respectively, in group 1, whereas these rates were 82.8, 65.5, and 48.3 %, respectively, in group 2 (P = 0.046). Among the 58 patients in group 2, the 1-, 3-, and 5-year overall survival rates were 92.3, 65.4, and 46.2 %, respectively, in the repeated TACE group, and 81.3, 65.6, and 50 %, respectively, in the persistent observation group (P = 0.783).

CONCLUSION

Immediate radical therapy should be the first choice for advanced HCC patients who undergo successful TACE, and repeated TACE is unnecessary.

Anatomical substrates for direct interactions between hippocampus, medial prefrontal cortex, and the thalamic nucleus reuniens

The reuniens nucleus in the midline thalamus projects to the medial prefrontal cortex (mPFC) and the hippocampus, and has been suggested to modulate interactions between these regions, such as spindle-ripple correlations during sleep and theta band coherence during exploratory behavior. Feedback from the hippocampus to the nucleus reuniens has received less attention but has the potential to influence thalamocortical networks as a function of hippocampal activation. We used the retrograde tracer cholera toxin B conjugated to two fluorophores to study thalamic projections to the dorsal and ventral hippocampus and to the prelimbic and infralimbic subregions of mPFC. We also examined the feedback connections from the hippocampus to reuniens. The goal was to evaluate the anatomical basis for direct coordination between reuniens, mPFC, and hippocampus by looking for double-labeled cells in reuniens and hippocampus. In confirmation of previous reports, the nucleus reuniens was the origin of most thalamic afferents to the dorsal hippocampus, whereas both reuniens and the lateral dorsal nucleus projected to ventral hippocampus. Feedback from hippocampus to reuniens originated primarily in the dorsal and ventral subiculum. Thalamic cells with collaterals to mPFC and hippocampus were found in reuniens, across its anteroposterior axis, and represented, on average, about 8 % of the labeled cells in reuniens. Hippocampal cells with collaterals to mPFC and reuniens were less common (~1 % of the labeled subicular cells), and located in the molecular layer of the subiculum. The results indicate that a subset of reuniens cells can directly coordinate activity in mPFC and hippocampus. Cells with collaterals in the hippocampus-reuniens-mPFC network may be important for the systems consolidation of memory traces and for theta synchronization during exploratory behavior.

Factors associated with colonization of Streptococcus mutans in 8- to 32-month-old children: a cohort study

BACKGROUND

The factors involved in Streptococcus mutans colonization in young children are not clear. The aim of this study was to determine the factors associated with S. mutans colonization in 8- to 32-month-old children.

METHODS

A group of 225 caries-free 8-month-old children was recruited for the study. They were examined every six months until they were 32 months old to investigate their environmental factors, host factors and bacterial transmission factors. At baseline and during each examination, their teeth were checked for the presence of dental plaque and developmental defects of enamel, and S. mutans plaque status was assessed using a real-time PCR test.

RESULTS

Eight children (3.6%) showed S. mutans colonization by the age of 8 months. The percentages of colonization were 6.0% at 14 months, 16.2% at 20 months, 26.7% at 26 months, and 33.5% at 32 months. The results showed that females (p = 0.006), children with enamel hypoplasia (p = 0.024), children with low birth weights (p = 0.005), those who consume more sweets (p < 0.001), and those with a higher proportion of visible plaque (p = 0.020 and p = 0.041) were more likely to be colonized by S. mutans.

CONCLUSIONS

Streptococcus mutans colonization in young children was associated with gender, tooth enamel hypoplasia, low birth weight, frequent consumption of sweets and poor oral hygiene.

Inhibition of Liver Cancer Cell Proliferation and Migration by a Combination of (-)-Epigallocatechin-3- Gallate and Ascorbic Acid

A mixture of (-)-epigallocatechin-3-gallate (EGCG) and ascorbic acid exhibited 73.2% inhibition of SMMC-7721 cell proliferation in a soft agar colony formation assay, which was much higher than EGCG (40.4%) or ascorbic acid (12.4%) alone. In the cell migration assay, the mixture also significantly suppressed the migration of SMMC-7721 cells by 65.9% while EGCG and/or ascorbic acid did by 28.9% and 18.7%, respectively. Ascorbic acid was able to enhance the antioxidant activity of EGCG by decreasing the intracellular oxidative stress according to fluorographic analysis of oxidative stress. In conclusion, the combination of EGCG and ascorbic acid can strongly suppress the proliferation and metastasis of liver cancer cells, possibly with a mechanism associated with the scavenging of reactive oxygen species. All these events add to our knowledge of liver cancer chemotherapy.

Flagellin-PAc fusion protein is a high-efficacy anti-caries mucosal vaccine

We previously demonstrated that an anti-caries DNA vaccine intranasally administered with recombinant flagellin protein as a mucosal adjuvant enhanced salivary IgA response and conferred better protection against caries. However, the relatively weak immunogenicity of DNA vaccines and the necessity for a large quantity of antigens remain significant challenges. Here, we fused the flagellin derived from E. coli (KF) and target antigen PAc containing the A-P fragment of PAc from S. mutans (rPAc) to produce a single recombinant protein (KF-rPAc). The abilities of KF-rPAc to induce rPAc-specific mucosal and systemic responses and protective efficiency against caries following intranasal immunization were compared with those of rPAc alone or a mixture of rPAc and KF (KF + rPAc) in rats. Results showed that KF-rPAc promoted significantly higher rPAc-specific antibodies in serum as well as in saliva than did an equivalent dose of rPAc alone or a mixture of KF + rPAc. Intranasal immunization of 8.5 µg KF-rPAc could achieve 64.2% reduction of dental caries in rats. In conclusion, our study demonstrated that flagellin and PAc fusion strategy is promising for anti-caries vaccine development, and KF-rPAc could be used as an anti-caries mucosal vaccine.

Unsteady relativistic shock-wave diffraction by cylinders and spheres

The unsteady relativistic shock-wave diffraction patterns generated by a relativistic blast wave impinging on a circular cylinder and a sphere are numerically simulated using some high-resolution relativistic kinetic beam schemes in a general coordinate system for solving the relativistic Euler equations of gas dynamics. The diffraction patterns are followed through about 6 radii of travel of the incident shock past the body. The complete diffraction patterns, including regular reflection, transition from regular to Mach reflection, slip lines, and the complex shock-on-shock interaction at the wake region resulting from the Mach shocks collision behind the body are reported in detail. Computational results of several incident shock Mach numbers covering the near ultrarelativistic limit are studied. Various contours of flow properties including the Lorentz factor and velocity streamline plots are also presented to add a better understanding of the complex diffraction phenomena. The three-dimensional relieving effects of the sphere cases are evident and can be quantitatively evaluated as compared with the corresponding cylinder cases.

Relationship between time to positivity of blood culture with clinical characteristics and hospital mortality in patients with Escherichia coli bacteremia

BACKGROUND

Previous studies indicated that the time to positivity (TTP) of blood culture is a parameter correlating with degree of the bacteremia and outcome in patients with bloodstream infections caused by Escherichia coli (E. coli). The objective of this study was to further investigate the diagnostic and prognostic power of using TTP to predict E. coli bacteremia.

METHODS

A retrospective cohort study at two university hospitals was conducted. We retrieved all the medical records of those with E. coli bloodstream infection according to the records generated by their microbiology departments. Univariate and multivariate analyses were applied to identify clinical factors correlating with fast bacterial growth and significant prognostic factors for hospital mortality.

RESULTS

Medical records of 353 episodes of E. coli bacteremia diagnosed between January 1, 2007 and December 31, 2009 were retrieved in the investigation. Univariate analysis demonstrated that the TTP ≤ 7 hours group is associated with higher incidence of active malignancies (41.7% vs. 27.2%, P = 0.010), neutropenia (30% vs.14.3%, P = 0.007), primary bacteremia (55.0% vs. 33.4%, P = 0.002), and poorer outcome (hospital mortality 43.3% vs.11.9%, P = 0.000) than the TTP > 7 hours group. Multivariate analysis revealed that the significant predictors of hospital mortality, in rank order from high to low, were TTP (for TTP ≤ 7 hours, odds ratio (OR): 4.886; 95% confidence interval (CI): 2.572 - 9.283; P = 0.000), neutropenia (OR: 2.800; 95%CI: 1.428 - 5.490; P = 0.003), comedication of steroids or immunosuppressive agents (OR: 2.670; 95%CI: 0.971 - 7.342; P = 0.057).

CONCLUSIONS

Incidence of malignancies, neutropenia and primary bacteremia correlates with fast bacterial growth in patients with E. coli bacteremia. The parameter of TTP has been identified as a variable of highest correlation to hospital mortality and therefore can be potentially utilized as a mortality prognostic marker.

Chemical and biological differentiation of Cortex Phellodendri Chinensis and Cortex Phellodendri Amurensis

The Chinese herbal drug Cortex Phellodendri is derived from two species of PHELLODENDRON, P. CHINENSIS Schneid. and P. AMURENSE Rupr. Traditionally, Cortex Phellodendri Chinensis (CPC) and Cortex Phellodendri Amurensis (CPA) are used interchangeably because they are believed to share the same clinical efficacy. Berberine has been believed to be the active ingredient of the herbs. However, recent studies have shown that the content of berberine is much higher in CPC than in CPA. Interestingly, the majority of researches deal with CPA, the one with lower content of berberine. These observations provoke us to reconsider the active ingredients of Cortex Phellodendri. In this study, two traditional usages (antidiarrheal and antibacterial) of Cortex Phellodendri were compared with the chemical analysis of the two herb species used in its formulation. The results suggest that berberine is one of the active ingredients responsible for the antidiarrheal and antibacterial activities of the herbs, but that other chemical ingredients are also involved in regulating the biological actions of the herbal drug. These chemical ingredients may have the same or the opposite effect as berberine. The effectiveness of the herbs is more likely to correlate to the content of total alkaloids rather than to the content of berberine.

Scanning tunnelling microscope studies of angstrom-scale Co3O4 nanowires

We report the bottom-up assembly of an atomic-scale building block, which consists of four Co(3+) cations, two Co(2+) cations, and eight O(2-) anions, for generating one-dimensional Co(3)O(4) nanostructures with diameters ranging from 0.5 to 3 nm. Controlled experiments were carried out and the growth mechanism of the Co(3)O(4) nanowires was investigated. The effects of a single cation defect on the epitaxial growth of the one-dimensional nanostructures were investigated. We proposed a self-rectifying growth mechanism on the basis of direct experimental observations. This mechanism will help us to understand synthesized crystals usually exhibiting homogeneous composition and uniform morphology, though the existence of defects is inevitable in the growth process.

Risk of water contamination by nitrogen in Canada as estimated by the IROWC-N model

With increasing amounts of nitrogen (N) being added to farmland in the form of fertilizer and manure to optimize crop yields, and more broadly, to meet the growing demands for food, feed and energy, there are public concerns regarding its possible negative impact on the environment. An optimal balance between N requirements for production versus efficient N use is required, so as to minimize N losses from the agricultural system. An agri-environmental indicator i.e., the Indicator of the Risk of Water Contamination by Nitrogen (IROWC-N) was developed to assess the risk of N moving from agricultural areas into groundwater and/or nearby surface water bodies. The indicator linked the quantity of mineral nitrogen remaining in the soil at harvest, i.e., the Residual Soil Nitrogen (RSN) indicator, and the subsequent climatic conditions during the winter period. The results were assessed in terms of nitrate lost through leaching and nitrate concentration in the drainage water, expressed in five IROWC-N risk classes. Unlike previous versions of the indicator, the current model provided a more complete description of the soil-water balance, including the calculation of rainfall interception by crops, surface runoff, actual evapotranspiration and soil-water contents. Consequently, the current IROWC-N estimates differed markedly from those obtained previously. Between 1981 and 2006, the risk of water contamination by N in Canada was small, and reflected what was happening in the three Prairie provinces where 85% of Canada's farmland is located. However, the aggregated IROWC-N index, which is a combination of all five risk classes, increased steadily by 2.3% per year, from 6.7 in 1981 to 10.6 in 2006. The proportion of farmland in the very low IROWC-N risk class decreased from 88 to 78%; correspondingly, the proportion in the low risk class increased from 2 to 12%. The proportion of farmland in the moderate-, high- and very high-risk classes changed by less than 3% over time. The trends in IROWC-N in the Atlantic provinces were significantly worse than the national trend; for example, in Atlantic Canada, the aggregated IROWC-N index tripled from 27.8 in 1981 to 87.5 in 2006. Increases in fertilizer use (except in British Columbia), increases in livestock numbers in Manitoba and the Atlantic provinces, and an increase in legume crop acreage were the main factors that contributed to the increase in IROWC-N estimates. Climatic factors were also involved, as droughts reduced yields, N uptake and N leaching in many regions of Canada in 2001.

The preparation, cytocompatibility, and in vitro biodegradation study of pure beta-TCP on magnesium

Biodegradable and bioactive beta-tricalcium phosphate (beta-TCP) coatings were prepared on magnesium (Mg) in order to improve its biocompatibility by a chemical method. The tensile bonding strength of beta-TCP coating and Mg substrate was measured by the standard adhesion test (ISO 13779-4). And the cytocompatibility of beta-TCP coated Mg was studied by using human osteoblast-like MG63 cells. It was found that the MG63 cells could grow well on the surface of beta-TCP coated Mg and the cell viability on beta-TCP coated Mg was above 80% during the cocultivation of MG63 cells and beta-TCP coated Mg for 10 days, indicating no cytotoxicity. It was concluded that the beta-TCP coated Mg had good cytocompatibility. The degradation of Mg substrate with beta-TCP coating in vitro was studied in detail by XRD, EDX, SEM, and ICP. The results showed that a bone-like apatite continually formed on the surface of the sample with the degradation of both Mg substrate and beta-TCP coating in Hank's solution (a simulated body fluid). The biodegradation mechanism was preliminarily analyzed in the paper.

Preliminary experience with indications for liver transplantation for hepatolithiasis

OBJECTIVE

The aim of this study was to explore the indications for liver transplantation among patients with hepatolithiasis.

PATIENTS AND METHODS

Data from 1,431 consecutive patients who underwent surgical treatment from January 2000 to December 2006 were retrospectively collected for analysis. Surgical procedures included T-tube insertion combined with intraoperative cholangioscopic removal of intrahepatic stones, hepatectomy, cholangiojejunostomy, and liver transplantation.

RESULTS

Nine hundred sixty-one patients who had a stone located in the left or right intrahepatic duct underwent hepatectomy or T-tube insertion combined with intraoperative cholangioscopic removal of intrahepatic stones. The rate of residual stones was 7.5%. Four hundred seventy patients who had a stone located in the bilateral intrahepatic ducts underwent surgical procedures other than liver transplantation; the rate of residual stones was 21.7%. Only 15 patients with hepatolithiasis underwent liver transplantation; they all survived. According to the degree of biliary cirrhosis, recipients were divided into 2 groups: a group with biliary decompensated cirrhosis (n = 7), or group with compensated cirrhosis or no cirrhosis (n = 8). There were significant differences in operative times, transfusion volumes, and blood losses between the 2 groups (P < .05). In the first group, 6 of 7 patients experienced surgical complications, and in the second, 8 recipients recovered smoothly with no complications. Health status, disability, and psychological wellness of all recipients (n = 15) were significantly improved at 1 year after transplantation compared with pretransplantation (P < .05).

CONCLUSIONS

Liver transplantation is a possible method to address hepatolithiasis and secondary decompensated biliary cirrhosis or difficult to remove, diffusely distributed intrahepatic duct stones unavailable by hepatectomy, cholangiojejunostomy, and choledochoscopy.

Inhibitory effect of a novel resveratrol derivative on nitric oxide production in lipopolysaccharide-activated microglia

Excessive nitric oxide (NO) production by activated microglial cells has been implicated in various neurodegenerative diseases. In the present study, we found that a new resveratrol derivative, (E)-5-(3-nitrostyryl)benzene-1,3-diol (RV06), has a more potential inhibitory effect on the production of NO in LPS-activated N9 microglial cells, and the result was confirmed on primary rat microglial cells. Further studies showed that RV06 inhibited LPS-induced iNOS expression in N9 microglial cells, with no activity on direct scavenging nitric oxide radical in a cell-free environment. The results suggest that RV06 might be a potential anti-inflammatory agent or leading compound which can inhibit inflammatory responses of microglia.

Human high-density lipoprotein particles prevent activation of the JNK pathway induced by human oxidised low-density lipoprotein particles in pancreatic beta cells

AIMS/HYPOTHESIS

We explored the potential adverse effects of pro-atherogenic oxidised LDL-cholesterol particles on beta cell function.

MATERIALS AND METHODS

Isolated human and rat islets and different insulin-secreting cell lines were incubated with human oxidised LDL with or without HDL particles. The insulin level was monitored by ELISA, real-time PCR and a rat insulin promoter construct linked to luciferase gene reporter. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei.

RESULTS

Prolonged incubation with human oxidised LDL particles led to a reduction in preproinsulin expression levels, whereas the insulin level was preserved in the presence of native LDL-cholesterol. The loss of insulin production occurred at the transcriptional levels and was associated with an increase in activator protein-1 transcriptional activity. The rise in activator protein-1 activity resulted from activation of c-Jun N-terminal kinases (JNK, now known as mitogen-activated protein kinase 8 [MAPK8]) due to a subsequent decrease in islet-brain 1 (IB1; now known as MAPK8 interacting protein 1) levels. Consistent with the pro-apoptotic role of the JNK pathway, oxidised LDL also induced a twofold increase in the rate of beta cell apoptosis. Treatment of the cells with JNK inhibitor peptides or HDL countered the effects mediated by oxidised LDL.

CONCLUSIONS/INTERPRETATION

These data provide strong evidence that oxidised LDL particles exert deleterious effects in the progression of beta cell failure in diabetes and that these effects can be countered by HDL particles.

Incomplete discoid glenoid labrum combined with a ganglion cyst of the spinoglenoid notch

In a 41-year-old man, right-sided infraspinatus muscle weakness was associated with compression of the suprascapular nerve caused by a spinoglenoid ganglion cyst. The lesion was confirmed using electromyography and MRI. In addition, arthroscopy showed an incomplete discoid labrum. The free inner edge of the labrum was removed as in a meniscectomy of a discoid meniscus in the knee joint. Arthroscopic decompression of the cyst was performed through a juxtaglenoid capsulotomy which was left open. Neurological function recovered completely.

Effects of pH, organic acids, and inorganic ions on lead desorption from soils

The desorption characteristics of lead in two variable charge soils (one developed from Arenaceous rock (RAR) and the other derived from Quaternary red earths (REQ)) were studied, and the effects of pH value, organic acid, and competitive ions were examined. Desorption of Pb(2+) decreased from nearly 100.0 to 20.0% within pH 1.0-4.0 in both soils, and then the decrease diminished at pH > 4.0. Organic ligands at relatively low concentrations (< or =10(-3) mol L(-1)) slightly inhibited Pb(2+) desorption, but enhanced Pb(2+) desorption at higher concentrations. In this study, citric acid or acetic acid at higher concentrations (>10(-3) mol L(-1)) had the greatest improvement of Pb(2+) desorption, followed by malic acid; and the smallest was oxalic acid. Desorption of the adsorbed Pb(2+) increased greatly with increasing concentrations of added Cu(2+) or Zn(2+). Applied Cu(2+) increased Pb(2+) desorption more than Zn(2+) at the same loading.

Tooth survival and periodontal tissues healing of allogenic-transplanted teeth in the mice

OBJECTIVE

For the successful organ transplantation, immune rejection has to be considered. Autogenic transplantation of human teeth is generally carried out free of clinical difficulty because of the lack of immune reaction, whereas allogenic tooth transplantations easily induce host immune rejection to donor tissues. The aim of the present study was to evaluate the replacement of donor tissue by host cells after allogenic tooth transplantation.

MATERIALS AND METHODS

First molars extracted from lacZ transgenic ROSA26 mice were transplanted into the alveolar socket and the tongue of host wildtype mice, where the first molar had existed.

RESULTS

Donor cells from lacZ transgenic mice were not detected in the periodontal ligament space, but rather in the pulp chamber of the donor tooth. Furthermore, if the pulp chamber was widely open to an affluent blood supply, odontoblasts and fibroblasts in the donor tissue survived in the dental pulp.

CONCLUSIONS

Our experimental models using lacZ transgenic ROSA26 mice clearly demonstrate that donor periodontal tissue cells are replaced by host cells and that periodontal tissue can regenerate after allogenic tooth transplantation. Furthermore, our models suggest that donor pulpal cells can survive if the vascular supply into the pulp chamber is sufficient.

Leaching potential of heavy metals (Cd, Ni, Pb, Cu and Zn) from acidic sandy soil amended with dolomite phosphate rock (DPR) fertilizers

There is an increasing concern on heavy metal leaching from the soils amended with sewage sludge. A column study was conducted to examine the extent of leaching of five important heavy metals (Cd, Ni, Pb, Cu and Zn) from an acidic sandy soil amended with different dolomite phosphate rock (DPR) fertilizers (an application rate of 1% fertilizers) developed from DPR and N-Viro (consisting of biosolids and fly ash) at 0%, 10%, 20%, 30%, 40%, 50% and 100% DPR. Ten leaching events were carried out with each event done at an interval of 7 days and with total leaching volume of 1183mm, which is equivalent to the mean annual rainfall of this region during the period of 2001-2003. Leachate was collected after each leaching event and analyzed for heavy metals. The maximum leachate concentrations of Cd, Ni, Pb, Cu and Zn were all below drinking water quality guidance limits set by Florida Department of Environmental Protection and World Health Organization, suggesting that the application of DPR fertilizers may not pose a threat to water quality by leaching. Most of leachate concentrations of Cd, Ni and Pb were below their detection limits and there were no significant differences between the control and the treatments with different DPR fertilizers. By contrast, there were higher leachate concentrations of Cu and Zn (ranging from 0.7 to 37.1mug Cu/l and 5.1 to 205.6mug Zn/l for all treatments) due to their higher contents in both the soil and different DPR fertilizers compared with Cd, Ni and Pb. The leachate concentrations of Cu and Zn for each treatment decreased with increasing leaching events. The differences in leachate concentrations of Cu and Zn between the control and the treatments with different DPR fertilizers containing N-Viro were significant, especially in the first several leaching events and, moreover, they increased with increasing proportion of N-Viro in the DPR fertilizers. There were similar trends in total losses of Cu and Zn after ten leaching events. Greater differences in both leachate concentrations and total losses of Zn between the control and the treatments containing N-Viro were noted. Total losses of Zn for the treatments containing N-Viro were 3.0-5.1 times higher than those for the control compared with 1.4-2.2 times higher for total losses of Cu, suggesting that greater proportions of Zn losses came from the DPR fertilizers due to the greater mobility of Zn in the DPR fertilizers compared with Cu.

Adsorption-desorption characteristics of lead in variable charge soils

Adsorption desorption processes of Pb at contaminated levels in two variable charge soils were investigated. The red soil (RAR) developed on the Arenaceous rock (clayey, mixed siliceous thermic typic Dystrochrept) adsorbed more Pb2+ than the red soil (REQ) derived from the Quaternary red earths (clayey, kaolinitic thermic plinthite Aquult). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 52.6 mmol Pb2+ kg(-1) soil and 29.9 mmol Pb2+ kg(-1) soil, respectively, for the RAR and REQ. Adsorption of Pb2+ decreased soil pH by 1.10 unit for the RAR soil and 1.21 unit for the REQ soil at the highest loading. The adsorption equilibrium pH of RAR was higher than that of REQ at the same Pb2+ concentration. The distribution coefficient (Kd) of Pb in the soils decreased exponentially with increasing Pb2+ loading. Most of the adsorbed Pb2+ in the soils was not desorbed in the 0.01 mol L(-1) NaNO3 solution. After five successive extractions with NaNO3, only 0-11% of the total adsorbed Pb2+ in the RAR soil was desorbed and the corresponding value of the REQ soil was 0-19%, indicating that the RAR soil had a greater affinity for Pb2+ than the REQ soil at the same Pb2+ loading. Different mechanisms might be involved in Pb2+ adsorption/desorption at different levels of Pb2+ loading and between the two soils.