Evaluating microcystinase A-based approach on microcystins degradation during harvested cyanobacterial blooms

Addressing notorious and worldwide Microcystis blooms, mechanical algae harvesting is an effective emergency technology for bloom mitigation and removal of nutrient loads in waterbodies. However, the absence of effective methods for removal of cyanobacterial toxins, e.g., microcystins (MCs), poses a challenge to recycle the harvested Microcystis biomass. In this study, we therefore introduced a novel approach, the "captured biomass-MlrA enzymatic MC degradation", by enriching microcystinase A (MlrA) via fermentation and spraying it onto salvaged Microcystis slurry to degrade all MCs. After storing the harvested Microcystis slurry, a rapid release of extracellular MCs occurred within the initial 8 h, reaching a peak concentration of 5.33 μg/mL at 48 h during the composting process. Upon spraying the recombinant MlrA crude extract (about 3.36 U) onto the Microcystis slurry in a ratio of 0.1% (v/v), over 95% of total MCs were degraded within a 24-h period. Importantly, we evaluated the reliability and safety of using MlrA extracts to degrade MCs. Results showed that organic matter/nutrient contents, e.g. soluble proteins, polysaccharides, phycocyanin and carotenoids, were not significantly altered. Furthermore, the addition of MlrA extracts did not significantly change the bacterial community composition and diversity in the Microcystis slurry, indicating that the MlrA extracts did not increase the risk of pathogenic bacteria. Our study provides an effective and promising method for the pre-treatment of harvested Microcystis biomass, highlighting an ecologically sustainable framework for addressing Microcystis blooms.

Biological Properties of 3D-Printed Zirconia Implants with p-Cell Structures

Research on 3-dimensional (3D) printed porous zirconia-based dental implants is still in its infancy. This study aimed to evaluate the biological responses of novel zirconia implants with p-cell structures fabricated by 3D printing. The solid zirconia samples exhibited comparable density, 3-point flexural strength, and accelerated aging properties compared to specimens prepared previously by conventional methods. Cell-based experiments showed that the p-cell structure promoted cell proliferation, adhesion, and osteogenesis-related protein expression. Mechanical tests showed that both p-cell and control implants could withstand a torque of 35 Ncm without breaking. The mean maximum breaking loads of p-cell and control implants were 1,222.429 ± 115.591 N and 1,903.857 ± 250.673 N, respectively, which were much higher than the human physiological chewing force and human mean maximum occlusal force. An animal experiment showed that the bone trabeculae around the implants were significantly thicker, more numerous, and denser in the p-cell group than in the control group. This work could provide promising guidance for further exploring 3D printing techniques for porous zirconia bionic implants in dentistry.

Changes in CO2 concentration drive a succession of toxic and non-toxic strains of Microcystis blooms

The dynamic changes between toxic and non-toxic strains of Microcystis blooms have always been a hot topic. Previous studies have found that low CO2 favors toxic strains, but how changing dissolved CO2 (CO2 [aq]) in water body influences the succession of toxic and non-toxic strains in Microcystis blooms remains uncertain. Here, we combined laboratory competition experiments, field observations, and a machine learning model to reveal the links between CO2 changes and the succession. Laboratory experiments showed that under low CO2 conditions (100-150 ppm), the toxic strains could make better use of CO2 (aq) and be dominant. The non-toxic strains demonstrated a growth advantage as CO2 concentration increased (400-1000 ppm). Field observations from June to November in Lake Taihu showed that the percentage of toxic strains increased as CO2 (aq) decreased. Machine learning highlighted links between the inorganic carbon concentration and the proportion of advantageous strains. Our findings provide new insights for cyanoHABs prediction and prevention.

Changes in nitrogen metabolism of phosphorus-starved bloom-forming cyanobacterium Microcystis aeruginosa: Implications for nutrient management

The surplus of nitrogen plays a key role in the maintenance of cyanobacterial bloom when phosphorus has already been limited. However, the interplay between high nitrogen and low phosphorus conditions is not fully understood. Nitrogen metabolism is critical for the metabolism of cyanobacteria. Transcriptomic analysis in the present study suggested that nitrogen metabolism and ribosome biogenesis were the two most significantly changed pathways in long-term phosphorus-starved bloom-forming cyanobacteria Microcystis aeruginosa FACHB-905. Notably, the primary glutamine synthetase/glutamate synthase cycle, crucial for nitrogen metabolism, was significantly downregulated. Concurrently, nitrogen uptake showed a marked decrease due to reduced expression of nitrogen source transporters. The content of intracellular nitrogen reservoir phycocyanin also showed a drastic decrease upon phosphorus starvation. Our study demonstrated that long-term phosphorus-starved cells also suffered from nitrogen deficiency because of the reduction in nitrogen assimilation, which might be limited by the reduced ribosome biogenesis and the shortage of adenosine triphosphate. External nitrogen supply will not change the transcriptions of nitrogen metabolism-related genes significantly like that under phosphorus-rich conditions, but still help to maintain the survival of phosphorus-starved cells. The study deepens our understanding about the survival strategies of Microcystis cells under phosphorus starvation and the mutual dependence between nitrogen and phosphorus, which would provide valuable information for nutrient management in the eutrophicated water body.

Non-targeted metabolomic profiling of filamentous cyanobacteria Aphanizomenon flos-aquae exposed to a concentrated culture filtrate of Microcystis aeruginosa

Microcystis and Aphanizomenon are two toxic cyanobacteria genera, which frequently cause blooms in freshwater lakes. In some cases, succession of these two genera was observed in natural water bodies. Among the diverse factors contributing to such succession of dominant cyanobacterial genera, an allelopathic effect was proposed to be involved after the growth inhibitory effect of several Microcystis species on A. flos-aquae was investigated. However, the response of target species exposed to Microcystis are poorly described. In the present study, we used two toxic cyanobacteria strains, Aphanizomenon flos-aquae (Aph1395) and Microcystis aeruginosa strain 905 (Ma905) as research subjects. Aph1395 was inhibited with a necessarily concentrated culture filtrate of Ma905 (MA905-SPE), and the response of the inhibited Aph1395 cells was explored via non-targeted metabolomic profiling. In total, 3735 features were significantly different in the Aph1395 treated with Ma905-SPE vs. those treated with BG11 medium. Among them, the annotations of 146 differential features were considered to be confident via MS/MS spectrum matching analysis. Based on the reported physiological functions of the annotated differential features, we proposed a putative model that in the growth-inhibited Aph1395, a suite of increased or decreased features with activities in apoptosis, growth inhibition, and stress response processes contributed to, or defended against, the allelopathic effect caused by Ma905. Our findings provide insights into the interaction between the bloom forming cyanobacterial species that share the same ecological environment.

Widespread Distribution and Adaptive Degradation of Microcystin Degrader (mlr-Genotype) in Lake Taihu, China

Microbial degradation is an important route for removing environmental microcystins (MCs). Here, we investigated the ecological distribution of microcystin degraders (mlr-genotype), and the relationship between the substrate specificity of the microcystin degrader and the profile of microcystin congener production in the habitat. We showed that microcystin degraders were widely distributed and closely associated with Microcystis abundance in Lake Taihu, China. We characterized an indigenous degrader, Sphingopyxis N5 in the northern Lake Taihu, and it metabolized six microcystin congeners in increasing order (RR > LR > YR > LA > LF and LW). Such a substrate-specificity pattern was congruent to the order of the dominance levels of these congeners in northern Lake Taihu. Furthermore, a meta-analysis on global microcystin degraders revealed that the substrate-specificity patterns varied geographically, but generally matched the profiles of microcystin congener production in the degrader habitats, and the indigenous degrader typically metabolized well the dominant MC congeners, but not the rare congeners in the habitat. This highlighted the phenotypic congruence between microcystin production and degradation in natural environments. We theorize that such congruence resulted from the metabolic adaptation of the indigenous degrader to the local microcystin congeners. Under the nutrient microcystin selection, the degraders might have evolved to better exploit the locally dominant congeners. This study provided the novel insight into the ecological distribution and adaptive degradation of microcystin degraders.

Cyanobacterial blooms in China: diversity, distribution, and cyanotoxins

Cyanobacterial blooms, which refer to the massive growth of harmful cyanobacteria, have altered the global freshwater ecosystems during the past decades. China has the largest population in the world, and it is suffering from the harmful effect of water eutrophication and cyanobacterial blooms along with rapid development of the economy and society. Research on cyanobacterial blooms and cyanotoxins in China have been overwhelmingly enhanced and emphasized during the past decades. In the present review, the research on cyanobacterial blooms in China is generally introduced, including the history of cyanobacterial bloom studies, the diversity of the bloom-forming cyanobacteria species (BFCS), and cyanotoxin studies in China. Most studies have focused on Microcystis, its blooms, and microcystins. Newly emerging blooms with the dominance of non-Microcystis BFCS have been gradually expanding to wide regions in China. Understanding the basic features of these non-Microcystis BFCS and their blooms, including their diversity, occurrence, physio-ecology, and harmful metabolites, will provide direction on future studies of cyanobacterial blooms in China.

Quantitative Proteomic and Microcystin Production Response of Microcystis aeruginosa to Phosphorus Depletion

Microcystis blooms are the most widely distributed and frequently occurring cyanobacterial blooms in freshwater. Reducing phosphorus is suggested to be effective in mitigating cyanobacterial blooms, while the underlying molecular mechanisms are yet to be elucidated. In the present study, isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics was employed to study the effects of phosphorus depletion on Microcystis aeruginosa FACHB-905. The production of microcystins (MCs), a severe hazard of Microcystis blooms, was also analyzed. In total, 230 proteins were found to be differentially abundant, with 136 downregulated proteins. The results revealed that, upon phosphorus limitation stress, Microcystis aeruginosa FACHB-905 raised the availability of phosphorus primarily by upregulating the expression of orthophosphate transport system proteins, with no alkaline phosphatase producing ability. Phosphorus depletion remarkably inhibited cell growth and the primary metabolic processes of Microcystis, including transcription, translation and photosynthesis, with structures of photosystems remaining intact. Moreover, expression of nitrogen assimilation proteins was downregulated, while proteins involved in carbon catabolism were significantly upregulated, which was considered beneficial for the intracellular balance among carbon, nitrogen and phosphorus. The expression of MC synthetase was not significantly different upon phosphorus depletion, while MC content was significantly suppressed. It is assumed that phosphorus depletion indirectly regulates the production of MC by the inhibition of metabolic processes and energy production. These results contribute to further understanding of the influence mechanisms of phosphorus depletion on both biological processes and MC production in Microcystis cells.

The involvement of α-proteobacteria Phenylobacterium in maintaining the dominance of toxic Microcystis blooms in Lake Taihu, China

Lake Taihu in China has suffered serious harmful cyanobacterial blooms for decades. The algal blooms threaten the ecological sustainability, drinking water safety, and human health. Although the roles of abiotic factors (such as water temperature and nutrient loading) in promoting Microcystis blooms have been well studied, the importance of biotic factors (e.g. bacterial community) in promoting and meditating Microcystis blooms remains unclear. In this study, we investigated the ecological dynamics of bacterial community, the ratio of toxic Microcystis, as well as microcystin in Lake Taihu. High-throughput 16S rRNA sequencing and principal component analysis (PCA) revealed that the bacteria community compositions (BCCs) clustered into three groups, the partitioning of which corresponded to that of groups according to the toxic profiles (the ratio of toxic Microcystis to total Microcystis, and the microcystin concentrations) of the samples. Further Spearman's correlation network showed that the α-proteobacteria Phenylobacterium strongly positively correlated with the toxic profiles. Subsequent laboratory chemostats experiments demonstrated that three Phenylobacterium strains promoted the dominance of the toxic Microcystis aeruginosa PCC7806 when co-culturing with the non-toxic PCC7806 mcyB^- mutant. Taken together, our data suggested that the α-proteobacteria Phenylobacterium may play a vital role in the maintenance of toxic Microcystis dominance in Lake Taihu.

Microcystin-LR Degradation and Gene Regulation of Microcystin-Degrading Novosphingobium sp. THN1 at Different Carbon Concentrations

The bacterium Novosphingobium sp. THN1 (THN1) is capable of degrading microcystin-LR (MC-LR). To study the ability of THN1 to degrade MC-LR and its possible mechanism(s) of regulation, we analyzed the effect of carbon concentrations on the degradation process. The MC-LR degradation rate peaked early and then declined during MC-LR biodegradation. Decreased levels of carbon in the medium caused the degradation peak to occur earlier. The expression of the functional gene mlrA, encoding a microcystinase, showed a similar trend to the MC-LR degradation rate at various carbon concentrations (r² = 0.717, p < 0.05), suggesting that regulation of mlrA expression may play an important role in MC-LR degradation by THN1. The total bacterial biomass decreased when the carbon source was limited and did not correlate with the MC-LR degradation rate. Transcriptomic analysis showed that MC-LR degradation differentially regulated 62.16% (2597/4178) of THN1 genes. A considerable number of differentially expressed genes (DEGs) during MC-LR degradation encoded proteins related to carbon-, nitrogen-, and amino acid-related pathways. At 2 h of MC-LR degradation, most DEGs (29/33) involved in carbon and nitrogen metabolism were downregulated. This indicated that MC-LR may regulate carbon and nitrogen pathways of Novosphingobium sp. THN1. KEGG pathway analysis indicated that the upregulated DEGs during MC-LR degradation were mainly related to amino acid degradation and substrate metabolism pathways. Particularly, we detected increased expression of glutathione metabolism-related genes from transcriptomic data at 2 h of MC-LR degradation compared with the gene expression of 0 h, such as GST family protein, glutathione peroxidase, S-(hydroxymethyl) glutathione dehydrogenase, and glutathione-dependent disulfide-bond oxidoreductase that have been reported to be involved in microcystin degradation.

The highly heterogeneous methylated genomes and diverse restriction-modification systems of bloom-forming Microcystis

The occurrence of harmful Microcystis blooms is increasing in frequency in a myriad of freshwater ecosystems. Despite considerable research pertaining to the cause and nature of these blooms, the molecular mechanisms behind the cosmopolitan distribution and phenotypic diversity in Microcystis are still unclear. We compared the patterns and extent of DNA methylation in three strains of Microcystis, PCC 7806SL, NIES-2549 and FACHB-1757, using Single Molecule Real-Time (SMRT) sequencing technology. Intact restriction-modification (R-M) systems were identified from the genomes of these strains, and from two previously sequenced strains of Microcystis, NIES-843 and TAIHU98. A large number of methylation motifs and R-M genes were identified in these strains, which differ substantially among different strains. Of the 35 motifs identified, eighteen had not previously been reported. Strain NIES-843 contains a larger number of total putative methyltransferase genes than have been reported previously from any bacterial genome. Genomic comparisons reveal that methyltransferases (some partial) may have been acquired from the environment through horizontal gene transfer.

Microcystin-Bound Protein Patterns in Different Cultures of Microcystis aeruginosa and Field Samples

Micocystin (MC) exists in Microcystis cells in two different forms, free and protein-bound. We examined the dynamic change in extracellular free MCs, intracellular free MCs and protein-bound MCs in both batch cultures and semi-continuous cultures, using high performance liquid chromatography and Western blot. The results showed that the free MC per cell remained constant, while the quantity of protein-bound MCs increased with the growth of Microcystis cells in both kinds of culture. Significant changes in the dominant MC-bound proteins occurred in the late exponential growth phase of batch cultures, while the dominant MC-bound proteins in semi-continuous cultures remained the same. In field samples collected at different months in Lake Taihu, the dominant MC-bound proteins were shown to be similar, but the amount of protein-bound MC varied and correlated with the intracellular MC content. We identified MC-bound proteins by two-dimensional electrophoresis immunoblots and mass spectrometry. The 60 kDa chaperonin GroEL was a prominent MC-bound protein. Three essential glycolytic enzymes and ATP synthase alpha subunit were also major targets of MC-binding, which might contribute to sustained growth in semi-continuous culture. Our results indicate that protein-bound MC may be important for sustaining growth and adaptation of Microcystis sp.

Microcystin-degrading bacteria affect mcyD expression and microcystin synthesis in Microcystis spp

Cyanobacterial blooms occur increasingly often and cause ecological, economic and human health problems worldwide. Microcystins (MCs) are the dominant toxins produced by cyanobacteria and are implicated in epidemic disease and environmental problems. Extensive research has been reported on the various regulating factors, e.g., light, temperature, nutrients such as nitrogen and phosphorus, pH, iron, xenobiotics, and predators, that influence microcystin (MC) synthesis, but little is known about the effects of cyanobacteria-associated bacteria on MC synthesis. A considerable number of studies have focused on interactions between Microcystis species and their associated bacteria. In this study, we evaluated the effects of MC-degrading bacteria (MCDB) on MC synthesis gene mcyD expression and MC synthesis in axenic strain PCC7806, non-axenic strain FACHB905, and colony strain FACHB1325 of Microcystis by quantitative real-time polymerase chain reaction (RT-PCR) assay and enzyme-linked immunosorbent assay (ELISA). We demonstrate for the first time that MCDB can induce and up-regulate the MC production and transcriptional response of the mcyD gene of toxic Microcystis. On day 4 of the culturing experiment, the intracellular MC concentration and transcriptional response of mcyD of FACHB1325 were up-regulated 1.9 and 5.3-fold over that of the control, and for FACHB905 were up-regulated 1.8 and 4.2-fold over that of the control, respectively. On day 10, the transcriptional response of mcyD was up-regulated 21.3-fold in PCC7806. These results indicate that there are interactions between toxic Microcystis and MCDB, and MCDB may play a role in regulating mcyD expression in toxic Microcystis.

Multi-Year Assessment of Toxic Genotypes and Microcystin Concentration in Northern Lake Taihu, China

Lake Taihu is the third-largest freshwater lake in China and has been suffering from cyanobacterial blooms for over two decades. The northern part of the lake, Meiliang Bay, is known to be at high risk of dense and sustained Microcystis blooms and toxins. This study aimed to investigate and record the annual and seasonal dynamics of toxic genotype, Microcystis morphospecies succession and microcystin variation. It also aimed to find out the underlying driving factors influencing the dynamic changes. Microcystin (MC) and the Microcystis genotype were quantified using HPLC and quantitative real-time PCR, respectively. Our study, over three consecutive years, showed that the pattern of morphospecies succession was seasonally distinct and annually consistent. During the same period in 2012, 2013 and 2014, the average MC were, on dry weight basis, 733 μg·g⁻¹, 844 μg·g⁻¹, 870 μg·g⁻¹, respectively. The proportion of toxic Microcystis accounted for 41%, 44% and 52%, respectively. Cell bound microcystin was found to correlate with the percentage of toxic Microcystis. Based on historical and current data, we conclude that annual bloom toxicity was relatively stable or possibly increased over the last decade.

Distribution and population dynamics of potential anatoxin-a-producing cyanobacteria in Lake Dianchi, China

The occurrence of cyanobacterial blooms is often accompanied by a variety of toxic secondary metabolites known as cyanotoxins. Anatoxin-a (ATX-a) is a highly toxic cyanobacterial neurotoxin synthesized by numerous species (e.g., Aphanizomenon, Anabaena and Oscillatoria) that has received much public attention. In this study, we used molecular methods (PCR and qPCR) to track the presence and dynamics of ATX-a-producing cyanobacteria, Aphanizomenon and Anabaena in Lake Dianchi, China based on the anaC and cpcBA-IGS genes over a 23-month period (from June 2010 to April 2012). Results revealed that Aphanizomenon was the major potential ATX-a producer in Lake Dianchi and that they were most abundant in early spring and least abundant in summer, coinciding with observed Aphanizomenon blooms. It was found that the proportion of ATX-a toxigenic cells was lower in the northern part of the lake (2.1%) than the middle (16.7%) and southern parts (19.2%). The information on the spatio-temporal distributions of ATX-a-producing cyanobacteria obtained in this study will help to build management strategies to improve water quality for public health.

Harmful algal bloom removal and eutrophic water remediation by commercial nontoxic polyamine-co-polymeric ferric sulfate-modified soils

Harmful algal bloom has posed great threat to drinking water safety worldwide. In this study, soils were combined with commercial nontoxic polyamine poly(epichlorohydrin-dimethylamine) (PN) and polymeric ferric sulfate (PFS) to obtain PN-PFS soils for Microcystis removal and eutrophic water remediation under static laboratory conditions. High pH and temperature in water could enhance the function of PN-PFS soil. Algal removal efficiency increased as soil particle size decreased or modified soil dose increased. Other pollutants or chemicals (such as C, P, and organic matter) in eutrophic water could participate and promote algal removal by PN-PFS soil; these pollutants were also flocculated. During PN-PFS soil application in blooming field samples, the removal efficiency of blooming Microcystis cells exceeded 99 %, the cyanotoxin microcystins reduced by 57 %. Water parameters (as TP, TN, SS, and SPC) decreased by about 90 %. CODMn, PO4-P, and NH4-N also sharply decreased by >45 %. DO and ORP in water improved. Netting and bridging effects through electrostatic attraction and complexation reaction could be the two key mechanisms of Microcystis flocculation and pollutant purification. Considering the low cost of PN-PFS soil and its nontoxic effect on the environment, we proposed that this soil combination could be applied to remove cyanobacterial bloom and remediate eutrophic water in fields.

Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake

The increasing occurrence of Microcystis blooms is of great concern to public health and ecosystem due to the potential hepatotoxic microcystins (MCs) produced by these colonial cyanobacteria. In order to interpret the relationships between variations of Microcystis morphospecies and extracellular MC concentrations, the seasonal dynamics of phytoplankton community composition, MC concentrations, and environmental parameters were monitored monthly from August, 2009 to July, 2010. The results indicated that Microcystis dominated total phytoplankton abundance from May to December (96%-99% of total biovolume), with toxic Microcystis viridis and non-toxic Microcystis wesenbergii dominating after July (constituting 65%-95% of the Microcystis population), followed by M. viridis as the sole dominant species from November to January (49%-93%). Correlation analysis revealed that water temperature and nutrient were the most important variables accounting for the occurrence of M. wesenbergii, while the dominance of M. viridis was related with nitrite and nitrate. The relatively low content of MCs was explained by the association with a large proportion of M. viridis and M. wesenbergii, small colony size of Microcystis populations, and low water temperature, pH and dissolved oxygen. The extracellular MC (mean of 0.5±0.2μg/L) of water samples analyzed by enzyme-linked immunosorbent assay (ELISA) demonstrated the low concentrations of MC in Dianchi Lake which implied the low potential risk for human health in the basin. The survey provides the first whole lake study of the occurrence and seasonal variability of Microcystis population and extracellular MCs that are of particular interest for water quality monitoring and management.

α-N-methylation of damaged DNA-binding protein 2 (DDB2) and its function in nucleotide excision repair

DDB2 exhibits a high affinity toward UV-damaged DNA, and it is involved in the initial steps of global genome nucleotide excision repair. Mutations in the DDB2 gene cause the genetic complementation group E of xeroderma pigmentosum, an autosomal recessive disease manifested clinically by hypersensitivity to sunlight exposure and an increased predisposition to skin cancer. Here we found that, in human cells, the initiating methionine residue in DDB2 was removed and that the N-terminal alanine could be methylated on its α-amino group in human cells, with trimethylation being the major form. We also demonstrated that the α-N-methylation of DDB2 is catalyzed by the N-terminal RCC1 methyltransferase. In addition, a methylation-defective mutant of DDB2 displayed diminished nuclear localization and was recruited at a reduced efficiency to UV-induced cyclobutane pyrimidine dimer foci. Moreover, loss of this methylation conferred compromised ATM (ataxia telangiectasia mutated) activation, decreased efficiency in cyclobutane pyrimidine dimer repair, and elevated sensitivity of cells toward UV light exposure. Our study provides new knowledge about the posttranslational regulation of DDB2 and expands the biological functions of protein α-N-methylation to DNA repair.

Immunohistochemical investigation of the correlation between LIM kinase 1 expression and development and progression of human ovarian carcinoma

OBJECTIVES

LIM kinase 1 (LIMK1) is implicated in cellular mechanisms regulating tumour cell invasion and may be involved in ovarian carcinoma progression. This retrospective study, therefore, investigated expression of the LIMK1 gene in primary ovarian tumour tissue samples and evaluated the correlation between LIMK1 gene expression and progression of ovarian carcinoma.

METHODS

LIMK1 protein levels were detected by immunohistochemistry in ovarian tissue samples from 57 patients with primary ovarian epithelial tumours (benign, n = 13; borderline, n = 14; carcinoma, n = 30) and 10 patients with normal ovaries. LIMK1 protein levels were evaluated by calculating the product of the scores for stain intensity and percentage of cells stained.

RESULTS

There was a significant correlation between increasing LIMK1 protein levels and increasing disease severity, from normal ovarian tissues through benign and borderline tumours to ovarian carcinoma. There was also a significant correlation between increasing LIMK1 protein levels and increasingly poor levels of differentiation of ovarian carcinoma.

CONCLUSIONS

LIMK1 is associated with the development of ovarian cancer and with the level of tumour differentiation in patients with ovarian carcinoma.

Fast removal of cyanobacterial toxin microcystin-LR by a low-cytotoxic microgel-Fe(Ⅲ) complex

Eutrophication has become a serious environmental threat throughout the world. In particular, the presence of cyanobacteria toxins, especially microcystins (MCs), has become a severe problem. Inhibition of Microcystis growth in water resources is the most effective way to reduce MCs, but it is a long-term investment. In the present study, a microgel-Fe(Ⅲ) complex was developed for the fast removal of MC-LR. The microgel-Fe(Ⅲ) characteristics and the MC-LR removal dynamics in Milli-Q water and natural water were evaluated. The removal efficiency negatively correlated to the initial MC-LR concentration and pH value (2.0-11.5), but the kinetics was not significantly influenced. The presence of natural organic matter (NOM) in water slightly reduced MC-LR removal using microgel-Fe(Ⅲ). In addition, microgel-Fe(Ⅲ) removed 98.99% of MC-LR in 12 min, while for activated carbon, it took 15-24 h to reach equilibrium. Furthermore, methanol was found to regenerate the microgel-Fe(Ⅲ) after MC-LR removal for at least five regeneration cycles. Finally, the microgel-Fe(Ⅲ) material was made into a membrane so that MCs could be removed by filtration. Therefore, microgel-Fe(Ⅲ) is an effective technology and has a great potential in removing MC-LR from drinking water resources.

Abstract 817: Isothiocyanates inhibit proteasome activity and proliferation of multiple myeloma cells

Isothiocyanates (ITCs), including benzyl ITC (BITC), phenethyl ITC (PEITC), and sulforaphane, induce cell cycle arrest and apoptosis in a variety of cancer cells and animal models. Although studies show that reactive oxygen species (ROS) generation may be responsible, at least in part, for apoptosis induced by ITCs, our recent studies show that covalent binding to target proteins may actually be an important event triggering apoptosis (Cancer Res., 2007, JBC.,2008, and JBC., 2009). In this study, we report that BITC and PEITC significantly inhibit proteasome activity in a variety of cell types. Further studies show that ITCs inhibit both the 26S and 20S proteasome, presumably through direct binding, and that this inhibition is unrelated to either ROS generation or ITC-induced protein aggregation. The potency of ITC-induced proteasome inhibition correlates with the rapid accumulation of p53 (tumor suppressor) and IκB (NF-κB inhibitor). Finally, our results demonstrate that BITC and PEITC as stronger proteasome inhibitors significantly suppress growth of multiple myeloma cells through induction of cell cycle arrest at G2/M phase and apoptosis. These results suggest that proteasome, like tubulin, is a potential molecular target of ITCs, unraveling a novel mechanism by which ITCs may inhibit multiple myeloma cell growth. This study provides new leads for ITC compounds with therapeutic and preventative efficacies for multiple myeloma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 817. doi:10.1158/1538-7445.AM2011-817

Isothiocyanates inhibit proteasome activity and proliferation of multiple myeloma cells

Isothiocyanates (ITCs), including benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC) and sulforaphane, compounds found in cruciferous vegetable, are highly effective in inducing cell cycle arrest and apoptosis in a variety of cancer cells and animal models. Although some studies indicate that ITC-induced reactive oxygen species (ROS) generation may underlie apoptosis induction, our recent studies show that covalent binding to target proteins may be an important event triggering apoptosis. In this study, we report that BITC and PEITC significantly inhibit proteasome activity in a variety of cell types. Further studies show that ITCs inhibit both the 26S and 20S proteasomes, presumably through direct binding, and that this inhibition is unrelated to either ROS generation or ITC-induced protein aggregation. The potency of ITC-induced proteasome inhibition correlates with the rapid accumulation of p53 (tumor suppressor) and IκB nuclear factor-kappaB (nuclear factor-kappaB inhibitor). Finally, our results demonstrate that BITC and PEITC, the two strongest proteasome inhibitors, significantly suppress growth of multiple myeloma (MM) cells through induction of cell cycle arrest at G₂/M phase and apoptosis. This study suggests that proteasome, like tubulin, is a potential molecular target of ITCs, thus providing a novel mechanism by which ITCs strongly inhibit growth of MM cells and new leads in identifying compounds with therapeutic and preventative efficacies for MM. It also supports the future studies of ITCs as therapeutic and preventive agents for MM.

Sulforaphane activates heat shock response and enhances proteasome activity through up-regulation of Hsp27

It is conceivable that stimulating proteasome activity for rapid removal of misfolded and oxidized proteins is a promising strategy to prevent and alleviate aging-related diseases. Sulforaphane (SFN), an effective cancer preventive agent derived from cruciferous vegetables, has been shown to enhance proteasome activities in mammalian cells and to reduce the level of oxidized proteins and amyloid β-induced cytotoxicity. Here, we report that SFN activates heat shock transcription factor 1-mediated heat shock response. Specifically, SFN-induced expression of heat shock protein 27 (Hsp27) underlies SFN-stimulated proteasome activity. SFN-induced proteasome activity was significantly enhanced in Hsp27-overexpressing cells but absent in Hsp27-silenced cells. The role of Hsp27 in regulating proteasome activity was further confirmed in isogenic REG cells, in which SFN-induced proteasome activation was only observed in cells stably overexpressing Hsp27, but not in the Hsp27-free parental cells. Finally, we demonstrated that phosphorylation of Hsp27 is irrelevant to SFN-induced proteasome activation. This study provides a novel mechanism underlying SFN-induced proteasome activity. This is the first report to show that heat shock response by SFN, in addition to the antioxidant response mediated by the Keap1-Nrf2 pathway, may contribute to cytoprotection.

Sulforaphane protects Microcystin-LR-induced toxicity through activation of the Nrf2-mediated defensive response

Microcystins (MCs), a cyclic heptapeptide hepatotoxins, are mainly produced by the bloom-forming cyanobacerium Microcystis, which has become an environmental hazard worldwide. Long term consumption of MC-contaminated water may induce liver damage, liver cancer, and even human death. Therefore, in addition to removal of MCs in drinking water, novel strategies that prevent health damages are urgently needed. Sulforaphane (SFN), a natural-occurring isothiocyanate from cruciferous vegetables, has been reported to reduce and eliminate toxicities from xenobiotics and carcinogens. The purpose of the present study was to provide mechanistic insights into the SFN-induced antioxidative defense system against MC-LR-induced cytotoxicity. We performed cell viability assays, including MTS assay, colony formation assay and apoptotic cell sorting, to study MC-LR-induced cellular damage and the protective effects by SFN. The results showed that SFN protected MC-LR-induced damages at a nontoxic and physiological relevant dose in HepG2, BRL-3A and NIH 3T3 cells. The protection was Nrf2-mediated as evident by transactivation of Nrf2 and activation of its downstream genes, including NQO1 and HO-1, and elevated intracellular GSH level. Results of our studies indicate that pretreatment of cells with 10muM SFN for 12h significantly protected cells from MC-LR-induced damage. SFN-induced protective response was mediated through Nrf2 pathway.

A cautionary note on using N-acetylcysteine as an antagonist to assess isothiocyanate-induced reactive oxygen species-mediated apoptosis

N-Acetylcysteine (NAC) has been widely used in cell culture-based studies for the role of reactive oxygen species (ROS) generation in apoptosis induction by isothiocyanates (ITCs). Here we have demonstrated, using [(14)C]phenethyl ITC and [(14)C]sulforaphane, that NAC pretreatment significantly reduces ITC cellular uptake by conjugating with ITCs in the medium, suggesting that reduced uptake of ITCs, rather than the antioxidant activity of NAC itself, is responsible for the diminished downstream apoptotic effects. The study provides a cautionary note on the assay in studying mechanisms of apoptosis by ITCs and other electrophilic and thiol-reactive compounds.

Increase of Mcm3 and Mcm4 expression in cervical squamous cell carcinomas

PURPOSE

To examine the relevance of expression of two proteins essential for DNA replication initiation, Mcm3 and Mcm4, in cervical squamous cell carcinoma (CSCC).

METHODS

53 cases of cervical squamous cell carcinoma, 35 cervical intraepithelial neoplasias (CIN) grade 2-3, 11 CIN I and 26 normal controls were studied. Immunohistochemistry was performed with anti-Mcm3 and anti-Mcm4 antibodies.

RESULTS

We found Mcm3 and Mcm4 protein expression had a tendency to be stronger from control to CSCC. Both Mcm3 and Mcm4 were significantly upregulated in squamous cervical carcinoma compared to the control, CIN grade 1 and grade 2-3 (p < 0.001), and Mcm3 expression was correlated with CSCC cell differentiation. However there were no independent prognosis correlations between Mcm3 and Mcm4 and clinicopathological parameters including age, stage, tumor size, invasive depth and lymph node metastasis.

CONCLUSIONS

Mcm3 and Mcm4 were highly expressed in CSCC, and these two proteins might be useful as biomolecular markers in clinical diagnosis.

Detection of microcystins in environmental samples using surface plasmon resonance biosensor

An indirect inhibitive surface plasmon resonance (SPR) immunoassay was developed for the microcystins (MCs) detection. The bioconjugate of MC-LR and bovine serum albumin (BSA) was immobilized on a CM5 sensor chip. A serial premixture of MC-LR standards (or samples) and monoclonal antibody (mAb) were injected over the functional sensor surface, and the subsequent specific immunoreaction was monitored on the BIAcore 3000 biosensor and generated a signal with an increasing intensity in response to the decreasing MCs concentration. The developed SPR immunoassay has a wide quantitative range in 1-100 microg L(-1). Although not as sensitive as conventional enzyme-linked immunosorbent assay (ELISA), the SPR biosensor offered unique advantages: (1) the sensor chip could be reusable without any significant loss in its binding activity after 50 assay-regeneration cycles, (2) one single assay could be accomplished in 50 min (including 30-min preincubation and 20-min BIAcore analysis), and (3) this method did not require multiple steps. The SPR biosensor was also used to detect MCs in environmental samples, and the results compared well with those obtained by ELISA. We conclude that the SPR biosensor offers outstanding advantages for the MCs detection and may be further developed as a field-portable sensor for real-time monitoring of MCs on site in the near future.

Cancer preventive isothiocyanates induce selective degradation of cellular alpha- and beta-tubulins by proteasomes

Although it is conceivable that cancer preventive isothiocyanates (ITCs), a family of compounds in cruciferous vegetables, induce cell cycle arrest and apoptosis through a mechanism involving oxidative stress, our study shows that binding to cellular proteins correlates with their potencies of apoptosis induction. More recently, we showed that ITCs bind selectively to tubulins. The differential binding affinities toward tubulin among benzyl isothiocyanate, phenethyl isothiocyanate, and sulforaphane correlate well with their potencies of inducing tubulin conformation changes, microtubule depolymerization, and eventual cell cycle arrest and apoptosis in human lung cancer A549 cells. These results support that tubulin binding by ITCs is an early event for cell growth inhibition. Here we demonstrate that ITCs can selectively induce degradation of both alpha- and beta-tubulins in a variety of human cancer cell lines in a dose- and time-dependent manner. The onset of degradation, a rapid and irreversible process, is initiated by tubulin aggregation, and the degradation is proteasome-dependent. Results indicate that the degradation is triggered by ITC binding to tubulin and is irrelevant to oxidative stress. This is the first report that tubulin, a stable and abundant cytoskeleton protein required for cell cycle progression, can be selectively degraded by a small molecule.

Reduction in microcystin concentrations in large and shallow lakes: water and sediment-interface contributions

Blooms of cyanobacteria, or blue-greens, are known to produce chemicals, such as microcystins, which can be toxic to aquatic and terrestrial organisms. Although previous studies have examined the fate of microcystins in freshwater lakes, primary elimination pathways and factors affecting degradation and loss have not been fully explained. The goal of the present study was to explore sources of algal toxins and investigate the distribution and biodegradation of microcystins in water and sediment through laboratory and field analyses. Water and sediment samples were collected monthly from several locations in Lake Taihu from February 2005 to January 2006. Samples were analyzed for the presence of microcystin. Water and sediment were also used in laboratory studies to determine microcystin degradation rates by spiking environmental samples with known concentrations of the chemical and observing concentration changes over time. Some water samples were found to efficiently degrade microcystins. Microcystin concentrations dropped faster in water collected immediately above lake sediment (overlying water). Degradation in sediments was higher than in water. Based on spatial distribution analyses of microcystin in Lake Taihu, higher concentrations (relative to water concentrations) of the chemical were found in lake sediments. These data suggest that sediments play a critical role in microcystin degradation in aquatic systems. The relatively low levels of microcystins found in the environment are most likely due to bacterial biodegradation. Sediments play a crucial role as a source (to the water column) of bio-degrading bacteria and as a carbon-rich environment for bacteria to proliferate and metabolize microcystin and other biogenic toxins produced by cyanobacteria. These, and other, data provide important information that may be applied to management strategies for improvement of water quality in lakes, reservoirs and other water bodies.

The expression of interleukin-10 in patients with primary ovarian epithelial carcinoma and in ovarian carcinoma cell lines

This study determined interleukin-10 (IL-10) expression in patients with ovarian carcinoma and in ovarian carcinoma cell lines, and investigated its clinical significance in the development and progression of ovarian carcinoma. Expression of IL-10 in ovarian carcinoma, benign ovarian tumour, normal control tissues and ovarian carcinoma cell lines was detected by immunohistochemistry and Western blot analysis. IL-10 concentrations in sera and ascites from patients with ovarian carcinoma, in sera from patients with benign ovarian tumour and normal controls, and in supernatants of ovarian carcinoma cell line cultures were measured by enzyme-linked immunosorbent assay. The tissue level of IL-10 in ovarian carcinoma was significantly higher than in benign ovarian tumour and normal controls. IL-10 expression was detectable in cell lysate and supernatant from ovarian carcinoma cell lines. In patients with ovarian carcinoma the IL-10 level in ascitic fluid was significantly higher than in sera, and the serum IL-10 level in ovarian carcinoma was significantly higher than in benign ovarian tumour and normal controls. Ascitic IL-10 levels in ovarian carcinoma were significantly correlated with disease stage but not cytological grade. These results suggest that ovarian carcinoma cells are able to synthesize and secrete IL-10, which probably assists in promoting the development and progression of ovarian carcinoma.

Distribution and bioaccumulation of microcystins in water columns: a systematic investigation into the environmental fate and the risks associated with microcystins in Meiliang Bay, Lake Taihu

For the purpose of understanding the environmental fate of microcystins (MCs) and the potential health risks caused by toxic cyanobacterial blooms in Lake Taihu, a systematic investigation was carried out from February 2005 to January 2006. The distribution of MCs in the water column, and toxin bioaccumulations in aquatic organisms were surveyed. The results suggested that Lake Taihu is heavily polluted during summer months by toxic cyanobacterial blooms (with a maximum biovolume of 6.7 x 10(8)cells/L) and MCs. The maximum concentration of cell-bound toxins was 1.81 mg/g (DW) and the dissolved MCs reached a maximum level of 6.69 microg/L. Dissolved MCs were always found in the entire water column at all sampling sites throughout the year. Our results emphasized the need for tracking MCs not only in the entire water column but also at the interface between water and sediment. Seasonal changes of MC concentrations in four species of hydrophytes (Eichhornic crassipes, Potamogeton maackianus, Alternanthera philoxeroides and Myriophyllum spicatum) ranged from 129 to 1317, 147 to 1534, 169 to 3945 and 124 to 956 ng/g (DW), respectively. Toxin accumulations in four aquatic species (Carassius auratus auratu, Macrobrachium nipponensis, Bellamya aeruginosa and Cristaria plicata) were also analyzed. Maximum toxin concentrations in the edible organs and non-edible visceral organs ranged from 378 to 730 and 754 to 3629 ng/g (DW), respectively. Based on field studies in Lake Taihu, risk assessments were carried out, taking into account the WHO guidelines and the tolerable daily intake (TDI) for MCs. Our findings suggest that the third largest lake in China poses serious health threats when serving as a source of drinking water and for recreational use. In addition, it is likely to be unsafe to consume aquatic species harvested in Lake Taihu due to the high-concentrations of accumulated MCs.

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: Risk assessment for groundwater protection

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha7 LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha7 LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha7 LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils.

Optimization of an effective extraction procedure for the analysis of microcystins in soils and lake sediments

Microcystin analysis in sediments and soils is considered very difficult due to low recovery for extraction. This is the primary limiting factor for understanding the fate of toxins in the interface between water and sediment in both the aquatic ecosystem as well as in soils. In the present study, a wide range of extraction solvents were evaluated over a wide range of pH, extraction approaches and equilibration time to optimize an effective extraction procedure for the analysis of microcystins in soils and lake sediments. The number of extractions required and acids in extraction solutions were also studied. In this procedure, EDTA-sodium pyrophosphate solution was selected as an extraction solvent based on the adsorption mechanism study. The optimized procedure proved to be highly efficient and achieved over 90% recovery. Finally, the developed procedure was applied to field soil and sediment sample collected from Chinese lakes during bloom seasons and microcystins were determined in six of ten samples.

Effects of microcystins on and toxin degradation by Poterioochromonas sp

A Chrysophyceae species, Poterioochromonas sp., was isolated from Microcystis cultures. This species can efficiently prey on Microcystis and can grow faster phagotrophically than autotrophically. The growth of Poterioochromonas sp. was stimulated in the presence of microcystin-LR and microcystin-RR (in concentrations ranging from 0.1 to 4 mg/L). The growth rate of Poterioochromonas was 4-5 times higher than the control, indicating the toxins serve as growth stimuli for this organism. A subculture of toxin-treated cells, however, showed low cellular viability, suggesting that growth enhancement by microcystins was not a normal process. The antioxidant enzymatic activity of Poterioochromonas sp. was screened for toxicology analysis. Glutathione, malondialdehyde, and superoxide dismutase (SOD) content was up-regulated within 8 h of exposure to microcystin-LR (500 microg/L). A high level of SOD activity during exposure to the toxin indicated that SOD was involved in decreasing oxidative stress caused by microcystin-LR. Simultaneously with growth, Poterioochromonas was able to degrade microcystin-LR even, at a toxin concentration of 4 mg/L. This putative degradation mechanism in Poterioochromonas is explored further and discussed in this article. Our findings may shed light on understanding the role of Poterioochromonas in the aquatic ecosystem, in particular, as a grazer of toxic cyanobacteria and a biodegrader for microcystins.

Chronic toxicity and responses of several important enzymes in Daphnia magna on exposure to sublethal microcystin-LR

In the current study, the toxicological mechanisms of microcystin-LR and its disadvantageous effects on Daphnia magna were examined. Survival rate, number of newborn, activity of several important enzymes [glutathione S-transferase (GST), lactate dehydrogenase (LDH), phosphatases, and glutathione], accumulated microcystins, and ultrastructural changes in different organs of Daphnia were monitored over the course of 21-day chronic tests. The results indicated that low concentrations of dissolved microcystin had no harmful effect on Daphnia. On the contrary, stimulatory effects were detected. In the presence of toxin at high dosage and for long-term exposure, GST and glutathione levels decreased significantly. The decreased enzyme activity in the antioxidant system probably was caused by detoxification reactions with toxins. And these processes of detoxification at the beginning of chronic tests may enable phosphatases in Daphnia magna to withstand inhibition by the toxins. At the same time, we also found that the LDH activity in test animals increased with exposure to microcystin-LR, indicating that adverse effects occurred in Daphnia. With microcystin given at a higher dosage or for a longer exposure, the effect on Daphnia magna was fatal. In the meantime, microcystin began to accumulate in Daphnia magna, and phosphatase activity started to be inhibited. From the ultrastructure results of cells in D. magna, we obtained new information: the alimentary canal may be the target organ affected by exposure of microcystins to D. magna. The results of the current study also suggested that the oxidative damage and PPI (protein phosphatase inhibition) mechanisms of vertebrates also are adapted to Daphnia.

Effects of microcystins on the growth and the activity of superoxide dismutase and peroxidase of rape (Brassica napus L.) and rice (Oryza sativa L.)

Microcystins are naturally occurring hepatotoxic cyclic heptapeptides produced by some toxic freshwater cyanobacterial species. In this study, crude extract of toxic cyanobacterial blooms from Dianchi Lake in southwestern China was used to determine the effects of microcystins on rape (Brassica napus L.) and rice (Oryza sativa L.). Experiments were carried out on a range of doses of the extract (equivalent to 0, 0.024, 0.12, 0.6 and 3 microg MC-LR/ml). Investigations showed that exposure to microcystins inhibited the growth and development of both rice and rape seedlings, however, microcystins had more powerful inhibition effect on rape than rice in germination percentage of seeds and seedling height. Microcystins significantly inhibited the elongation of primary roots of rape and rice seedlings. Determination of the activities of peroxidase and superoxide dismutase demonstrated that microcystin stress was manifested as an oxidative stress. Using ELISA, microcystins were examined from the extract of exposed rape and rice seedlings, indicating that consumption of edible plants exposed to microcystins via irrigation route may have health risks. Significantly different levels of recovered microcystins between exposed rice and rape seedlings suggested that there might be different tolerant mechanisms toward microcystins.

Neurotransmitter dopamine applied in electrochemical determination of aluminum in drinking waters and biological samples

It was demonstrated that the decrease of the differential pulse voltammetric (DPV) anodic peak current of dopamine (3,4-dihydroxyphenylethylamine, DA) was linear with the increase of aluminum (Al) concentration. Under optimum experimental conditions (pH 4.6, 1.2 x 10(-3) M DA, and 0.04 M NaAc-HAc buffer solution), the linear range is 4.0 x 10(-7)-8.0 x 10(-5) M, the detection limit is 1.4 x 10(-7) M, and the relative standard deviation for 4 x 10(-5) M Al(III) is 3.5% (n=8). Many foreign species, especially some low-molecule-weight biological molecules, were chosen for interference testing. The proposed method was applied to the determination of Al in biological samples such as synthetic renal dialysate, Ringer's solution, human blood, cerebrospinal fluid of a patient, and urine of a diabetic patient. The corresponding recoveries were generally between 95 and 105%. The basic principle of the method was determined by examining Al complexed with DA. This results in the blockage of the electroactive sites on DA, followed eventually by the reduction of the electrochemical response of DA. This result was verified by examining the behavior of DA, both in the presence and absence of Al, using electrochemical, UV-Vis, Raman, and (13)C NMR spectroscopic methods.

Speciation of aluminium(III) in natural waters using differential pulse voltammetry with a pyrocatechol violet-modified electrode

A differential pulse voltammetric (DPV) procedure is proposed for the speciation of aluminium in natural waters using Pyrocatechol Violet chemically modified electrodes (PCV-CMEs). This novel speciation idea is based on the selective determination of different AlIII forms under two pH conditions. The labile monomeric Al fraction (mainly inorganic Al) is analysed at pH 4.8 (0.20 mol dm(-3) NaOAc-HOAc) and the total monomeric Al fraction is analysed at pH 8.5 (0.20 mol dm(-3) NH3.H2O-NH4Cl). The difference is thought to be caused by the weak competition ability of PCV to sequester AlIII from AlIII-natural organic matter complexes. This sensitive and simple speciation method has been applied successfully to aluminium speciation in natural waters sampled from different regions of China. Five fractions are measured directly or indirectly: (i) labile monomeric Al; (ii) total monomeric Al; (iii) acid reactive Al; (iv) non-labile monomeric Al; and (v) acid soluble Al. The results are in satisfactory agreement with those obtained by Driscoll's 8-hydroxyquinoline extraction-ion exchange method.

Effects of a single drip infusion of lipo-prostaglandin E1 on vibratory threshold in patients with diabetic neuropathy

We evaluated acute effects of prostaglandin E1 encapsulated in lipid microspheres (lipo-PGE1), in 14 type 2 diabetic patients with neuropathy. Nerve conduction velocity (NCV), vibratory threshold (VT), skin temperature and subjective symptoms were evaluated for 24 hours after a single drip infusion of lipo-PGE1. In 6 of the 14 patients, the decrease in VT (P < 0.05) more than 50% measured by an SMV-5 vibrometer was observed at 6 hours after the infusion (responders). Subjective symptoms were improved (P < 0.05) in 5 of the 6 responders, whereas it improved in only 1 of the 8 patients who had no change in VT (nonresponders). NCV did not change (P > 0.05) either in the responders or in the nonresponders by the infusion. The responders had less impairment in VT and milder retinopathy and nephropathy than the nonresponders (P < 0.05). Our results demonstrate that vibratory sensation and subjective symptoms can be improved by a single infusion of lipo-PGE1 in type 2 diabetic patients with mild neuropathy.

The effects of goshajinkigan, a herbal medicine, on subjective symptoms and vibratory threshold in patients with diabetic neuropathy

Goshajinkigan, a herbal medicine, has long been used in Japan to alleviate the subjective symptoms of diabetic neuropathy; however, its effects have not been confirmed objectively. We evaluated its effects on subjective symptoms and on vibration sensation in patients with diabetic neuropathy. The oral administration of 7.5 g/day of Goshajinkigan for 3 months (treatment period) relieved subjective symptoms of numbness in 9 of 13 patients. When the drug was discontinued for 2 months as a washout period, the subjective symptom worsened in 7 of 13 patients. Chi-square analysis revealed significant effects of Goshajiniagan on subjective symptoms (P < 0.001 for numbness and P < 0.05 for cold sensation). Vibration sensation was evaluated by measuring vibratory threshold using an SMV-5 vibrometer. There were significant changes in vibratory thresholds by paired t-test (P < 0.05) both in the upper and the lower extremities during the treatment and washout periods. Chi-square analysis also revealed a significant effect of Goshajinkigan on vibratory threshold (P < 0.01). There was no significant change in glycosylated hemoglobin as a whole during the study. These observations confirm that Goshajinkigan relieves subjective symptoms and demonstrate that it improves vibration sensation in patients with diabetic neuropathy.

Variant forms of glucokinase gene in Japanese patients with late-onset type 2 diabetes

We have applied the technique of single-strand conformation polymorphism analysis to detect mutations of the glucokinase gene in 50 Japanese patients with late-onset type 2 diabetes and in 50 normal Japanese subjects. Out of the 50 patients with late-onset type 2 diabetes, we observed three kinds of variant patterns: one in exon 1b, one in exon 4, and one in exon 5. The incidence of these patterns was one in exon 1b, two in exon 4 and one in exon 5. Direct sequencing of exon 1b and exon 5 revealed mutations in intron areas at the 12th nucleotide downstream from the 5' splice points in two cases. Direct sequencing of exon 4 revealed a heterozygous silent mutation, CCC[Pro]-->CCG[Pro] at codon 145. In contrast, 50 normal Japanese subjects showed no variant patterns in any exons. Our results showed that although 8% (4 out of 50) of Japanese patients with late-onset type 2 diabetes have variant forms of the glucokinase gene, none is expected to cause apparent qualitative changes in glucokinase. We think that the frequency of mutations of the glucokinase gene which could cause qualitative change is very low in Japanese patients with late-onset type 2 diabetes.