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Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 217 records · Page 12Linked to original sources
PubMed1998

Interferon-gamma and human megakaryopoiesis.

Interferon-gamma (IFN-gamma) exhibits various properties including antigrowth activity in neoplastic and normal cells and regulatory roles in immune responses and hematopoiesis, but studies of IFN-gamma effects on human megakaryopoiesis have been inconclusive. Recently we have used serum-free culture of purified CD34+ cells to demonstrate that IFN-gamma stimulates the proliferation of relatively mature megakaryocytic progenitors independently of thrombopoietin. It has been also shown that IFN-gamma stimulates the maturation of megakaryocytes, and has a significant synergism with stem cell factor in human megakaryopoiesis. Further studies are needed to clarify the in vivo effect of IFN-gamma on human megakaryopoiesis and the clinical relevance of IFN-gamma.

Cellular Senescence↗
PubMed1998

[Allogeneic bone marrow transplantation in children from related donors other than HLA-identical siblings].

Thirty-five children with poor-prognosis disease underwent allogeneic bone marrow transplantation (BMT) from related donors other than HLA identical siblings (parents in 18 cases, non-identical siblings in 14, and other relatives in 3). Phenotypically identical donors were involved in 12 cases, donors with one mismatched locus in 17, and donors with two or more mismatched loci in 6. Thirty-two of the children received total-body irradiation as part of their conditioning regimen, followed by unpurged marrow-cell infusions (averaging 4.09 x 10(8) cells/kg). Methotrexate and cyclosporin were administered for graft-versus-host disease (GVHD) prophylaxis; 15 of the children also received antithymocyte globulin (ATG) infusions. The effective graft rate for the group was 84. 8%; of 5 patients who experienced rejections, 4 had non-malignant diseases. The incidence of grade II-IV acute GVHD was 48.4%, significantly higher than that for groups that received allogeneic BMT from matched sibling donors. Three children (8.8%) died of severe GVHD. The incidence of acute GVHD in phenotypically matched patients was the same as that in the one-locus mismatched cases. MLC reactivity affected the incidence of acute GVHD (60.0% MLC-positive, 28.6% negative). ATG reduced the severity of acute GVHD. The event-free survival rate was 40.8 +/- 8.5% for the entire group (N = 35; 32.9 +/- 10.5% for the 22 children with malignancies, and 53.8 +/- 13.8% for the 13 with non-malignant diseases). Despite the risk of severe GVHD, allogeneic BMT from related donors other than HLA-identical siblings seems to be an effective treatment for patients with poor-prognosis diseases.

Acute Disease↗
PubMed1997

Synergistic action of Flt3 and gp130 signalings in human hematopoiesis.

We recently showed that c-kit signal synergizes with glycoprotein (gp)130 signal mediated by a complex of interleukin (IL)-6 and soluble IL-6 receptor (IL-6/sIL-6R) to stimulate the expansion of human primitive hematopoietic progenitor cells and erythropoietin-independent erythropoiesis. In the present study, we examined the effect of a ligand for Flt3 (FL), whose receptor tyrosine kinase is closely related to c-kit, in combination with IL-6/sIL-6R on human hematopoiesis in vitro. In serum-containing methylcellulose clonal culture of cord blood CD34(+) cells, whereas FL alone stimulated only granulocyte-macrophage (GM) colony formation, erythroid bursts and mixed colonies in addition to GM colonies were induced by FL with IL-6/sIL-6R, but not IL-6/sIL-6R alone. In suspension culture, CD34(+) cells generated a small number of myeloid cells in the presence of FL or IL-6/sIL-6R alone. However, the addition of IL-6/sIL-6R to the culture with FL induced the generation of a significant number of erythroid cells and megakaryocytes in addition to myeloid cells. The combination of FL and IL-6/sIL-6R also induced a remarkable expansion of GM colony- and erythroid burst-forming cells and multipotential progenitors, although FL or IL-6/sIL-6R alone induced the generation of only a small number of progenitors for GM colonies. The synergistic effects of FL and IL-6/sIL-6R were confirmed in serum-free clonal and suspension cultures. In addition, the addition of anti-human gp130 monoclonal antibodies abrogated the synergistic action. These results indicate that Flt3 signal, as well as c-kit signal, synergizes with gp130 signal to stimulate human myelopoiesis, erythropoiesis and megakaryopoiesis, and the expansion of primitive multipotential hematopoietic progenitor cells.

Antibodies, Monoclonal↗
PubMed1997

Leptin stimulates the proliferation of murine myelocytic and primitive hematopoietic progenitor cells.

Leptin, the product of obese gene, was originally identified as a factor regulating body-weight homeostasis and energy balance. The present study has shown that leptin acts on murine hematopoiesis in vitro. In the culture of bone marrow cells (BMC) of normal mice, leptin induced only granulocyte-macrophage (GM) colony formation in a dose-dependent manner, and no other types of colonies were detected even in the presence of erythropoietin (Epo). Leptin also induced GM colony formation from BMC of db/db mutant mice whose leptin receptors were incomplete, but the responsiveness was significantly reduced. The effect of leptin on GM colony formation from BMC of normal mice was also observed in serum-free culture, and comparable with that of GM-colony-stimulating factor (CSF ). Although leptin alone supported few colonies from BMC of 5-fluorouracil (5-FU)-treated mice in serum-free culture, remarkable synergism between leptin and stem cell factor (SCF ) was obtained in the colony formation. The addition of leptin to SCF enhanced the SCF-dependent GM colony formation and induced the generation of a number of multilineage colonies in the presence of Epo. When lineage (Lin)-Sca-1(+) cells sorted from BMC of 5-FU-treated mice were incubated in serum-free culture, leptin synergized with SCF in the formation of blast cell colonies, which efficiently produced secondary colonies including a large proportion of multilineage colonies in the replating experiment. In serum-free cultures of clone-sorted Lin-c-Kit+Sca-1(+) and Lin-c-Kit+Sca-1(-) cells, although synergism of leptin and SCF was observed in the colony formation from both cells, leptin alone induced the colony formation from Lin-c-Kit+Sca-1(-), but not Lin-c-Kit+Sca-1(+) cells. These results have shown that leptin stimulates the proliferation of murine myelocytic progenitor cells and synergizes with SCF in the proliferation of primitive hematopoietic progenitors in vitro.

Animals↗
PubMed1997

Hematopoietic and lymphopoietic responses in human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor transgenic mice injected with human GM-CSF.

Using a clonal assay of bone marrow (BM) cells from transgenic mice (Tg-mice) expressing the human granulocyte-macrophage colony-stimulating factor receptor (hGM-CSFR), we found in earlier studies that hGM-CSF alone supported the development not only of granulocyte-macrophage colonies, but also of erythrocytes, megakaryocytes, mast cells, blast cells, and mixed hematopoietic colonies. In this report, we evaluated the in vivo effects of hGM-CSF on hematopoietic and lymphopoietic responses in the hGM-CSFR Tg-mice. Administration of this factor to Tg-mice resulted in dose-dependent increases in numbers of reticulocytes and white blood cells (WBCs) in the peripheral blood. Morphological analysis of WBCs showed that the numbers of all types of the cell, including neutrophils, eosinophils, monocytes, and lymphocytes increased; the most remarkable being in lymphocytes that contained a number of large granular lymphocytes (LGLs) in addition to mature T and B cells. However, total cellularity of the BM of the Tg-mice decreased in a dose-dependent manner when hGM-CSF was injected. In sharp contrast to the BM, spleens of the Tg-mice were grossly enlarged. Although all types of blood cells and hematopoietic progenitors increased in the spleen, erythroid cells and their progenitors showed the most significant increase. Increased numbers of megakaryocytes and LGLs were also observed in spleen and liver of the treated Tg-mice. Flow cytometric analysis showed that LGLs expanded in Tg-mice expressed Mac-1+ CD3- NK1.1+. The thymus of Tg-mice treated with hGM-CSF exhibited a dose-dependent shrinkage and a remarkable decrease in CD4+ CD8+ cells. Thus, hGM-CSF stimulated not only myelopoiesis but also erythropoiesis and megakaryopoiesis of hGM-CSFR Tg-mice in vivo, in accordance with our reported in vitro findings. In addition, hGM-CSF affected the development of lymphoid cells, including natural killer cells of these Tg-mice.

Animals↗
PubMed1997

Requirement of CD4 T cells for skin graft rejection against thymus leukemia (TL) antigen and multiple epitopes on the TL molecule recognized by CD4 T cells.

By selective depletion of CD4 and CD8 T cells in vivo using the respective mAbs, we demonstrate that CD4 T cells are necessary for skin graft rejection against thymus leukemia (TL) Ag. The skin expressing T3b-TL Ag from transgenic C3H Tg.Con.3-1 mice given chimeric H-2Kb/T3b-TL gene was rejected when grafted onto C3H/He recipient mice. Depletion of CD4, but not of CD8, T cells blocked rejection. CD8 CTL were generated in MEM (control)-treated C3H/He recipient mice, while Thy-1+ CD4- CD8- CTL were generated in CD8-depleted recipient mice after rejection. However, no CTL were generated in CD4-depleted or both CD4- and CD8-depleted recipient mice. Thus, the generation of both CD8 and Thy-1+ CD4- CD8- CTL was dependent on CD4 T cells. Ab blocking indicated that both CD8 and Thy-1+ CD4- CD8- CTL were TCR alphabeta and recognized TL Ag. We furthermore demonstrated that CD4 T cells in spleen cells from C3H/He mice that had rejected C3H Tg.Con.3-1 skin showed a weak, but significant, proliferative response to in vitro stimulation with mitomycin C-treated C3H Tg.Con.3-1 spleen cells. Analysis of the reactivity of bulk CD4 T cell lines to 73 synthetic overlapping peptides encompassing the entire T3b-TL molecule showed that CD4 T cells recognized multiple epitopes on the T3b-TL molecule in an APC-dependent manner.

Amino Acid Sequence↗
PubMed1997

Physical mapping 220 kb centromeric of the human MHC and DNA sequence analysis of the 43-kb segment including the RING1, HKE6, and HKE4 genes.

A cosmid contig was constructed from a YAC clone with a 220-kb insert that spans the centromeric side of the human MHC class II region, corresponding to the mouse t complex. The gene order was identified to be HSET-HKE1.5-HKE2-HKE3-RING1-HKE6- HKE4 (RING5). The genomic sequence of a 42,801-bp long region encoded by one cosmid clone in the RING1, HKE6, and HKE4 subregions was determined by the shotgun method. The exon-intron organization of these three genes, RING1 (Ring finger protein), HKE6 (steroid dehydrogenase-like protein), and HKE4 (transmembrane protein with histidine-rich charge clusters), was determined. The previously reported RING2 gene was revealed to be identical to HKE6. Transcripts from HKE4 were detected in the placenta, lung, kidney, and pancreas. Those of HKE6 were found in the liver and pancreas. The 25-kb region proximal to the RING1 gene includes an extensive dense cluster of Alu repeats (about 1.2 Alu per kb), and no gene has been identified in this so far. The region is equivalent to part of the mouse t complex and could be of relevance to human development.

Amino Acid Sequence↗
PubMed1997

Association between HLA-DPB1 matching and 1-year rejection-free graft survival in high-risk corneal transplantation.

We analyzed the effect of matching for HLA class II alleles on corneal graft outcome in a single-center, retrospective study from January 1991 through April 1996. The study involved 81 transplant recipients at high and low risk of corneal graft rejection, who were typed by the polymerase chain reaction-restriction fragment length polymorphism method and who completed at least 1-year of follow-up. The DRB1, DQB1, and DPB1 alleles were analyzed together and transplant recipients were subdivided into groups with matching (one to four alleles matched in the high risk or one to five alleles matched in the low risk) and without matching (no allele matched) for HLA class II. A significantly higher rate of 1-year rejection-free graft survival was revealed in high-risk transplant recipients with matching, compared with those without matching (P=0.0238). We have shown that matching for at least one HLA class II allele was actually beneficial in high-risk transplants. An analysis of matching for each allele separately, detected that only HLA-DPB1 matching was significantly associated with a higher rate of 1-year rejection-free graft survival in high-risk transplant recipients with matching (one or two alleles matched) compared with those without matching (no allele matched) (P=0.0139). In particular, matching for one DPB1 allele was significantly beneficial compared with no matching (P=0.0140). There was no significant effect of HLA-DRB1 and -DQB1 matching (P=0.3177 and P=0.2878, respectively). Furthermore, a strong association between DPB1 matching and 1-year rejection-free graft survival was observed in DRB1-incompatible high-risk transplant recipients (P=0.0308). Nevertheless, no significant effect of DPB1 matching was detected in DQB1-incompatible transplant recipients. Our findings indicate that HLA class II DNA typing is clinically relevant for corneal transplant recipients and that especially HLA-DPB1 matching has a beneficial effect in high-risk corneal transplantation.

Adolescent↗
PubMed1997

Antirheumatic agents: novel methotrexate derivatives bearing a benzoxazine or benzothiazine moiety.

Novel methotrexate (MTX) derivatives bearing dihydro-2H-1,4-benzothiazine or dihydro-2H-1,4-benzoxazine were synthesized and tested for in vitro antiproliferative activities against human synovial cells (hSC) and human peripheral blood mononuclear cells (hPBMC) obtained from patients with rheumatoid arthritis and healthy volunteers, respectively. In vivo antiarthritic activities of these derivatives were also evaluated in a rat adjuvant arthritis model. N-[[4-[(2,4-Diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-glutamic acid (3c) exhibited more potent antiproliferative activities in hSC and hPBMC than MTX in vitro. Antiproliferative activities of N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzoxazin-7-yl]carbonyl]-L-homoglutamic acid (3b) and N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-homoglutamic acid (3d) (MX-68) were comparable to that of MTX in these in vitro assays. Compounds 3b,d (MX-68) significantly suppressed progression of the adjuvant arthritis in a dose-dependent manner ranging from 0.5 to 2.5 mg/kg (po). In addition, 3d (MX-68) completely suppressed this progression at the dose of 2.5 mg/kg (po). Importantly, 3d (MX-68) having benzothiazine and homoglutamate, as expected, did not undergo polyglutamation, a process which may be responsible for the associated side effects of MTX. These results suggest that 3d (MX-68) is a potent and safe candidate antirheumatic agent, absent of the side effects of MTX.

Animals↗
PubMed1997

Clinical study of the relationship between cytological behavior and postoperative prognosis in colorectal cancer cases with special reference to nuclear DNA content and nucleolar organizer regions.

BACKGROUND: We studied the usefulness of nuclear DNA patterns and argyrophylic nucleolar organizer regions (AgNORs) for evaluating the malignant potential of colorectal cancers, which is increasingly being regarded as important in predicting patients' prognosis and for their appropriate postoperative management. METHODS: We measured these two factors in curatively resected specimens of 91 colorectal cancer cases, which were followed up for 1,549 +/- 788 days postoperatively. Ploidy pattern was either diploid or aneuploid, and AgNORs score was either low (LS) or high (HS). Thus, we classified our cases into Group I (diploid, LS). Group II (aneuploid, LS), Group III (diploid, HS), and Group IV (aneuploid, HS). Postoperative survival curves in the cases belonging to these groups were analyzed. RESULTS: Survival rates in Groups I and II were significantly higher than those in Group IV. Correlation between subgroups and clinicopathological factors such as average age, histologic type, depth of invasion, and histologic stage were observed. Incidence of lymph node metastasis at the time of operation and that of postoperative recurrence were higher in group IV than that in groups I and II. CONCLUSIONS: Measurement of DNA ploidy patterns and AgNORs score were found to be useful in evaluating malignant potential of colorectal cancers.

Adult↗
PubMed1997

Synchronous decline of serum-soluble HLA class I antigen and beta-cell function in insulin-dependent diabetes mellitus.

Serum-soluble HLA class I molecules (sHLA) have immunomodulatory functions and their serum levels correlate with the HLA class I phenotype. We studied longitudinal changes of serum sHLA levels in insulin-dependent diabetes mellitus (IDDM). A total of 198 serum samples were obtained from 40 IDDM patients before and after IDDM onset. sHLA was assayed by a sandwich ELISA. sHLA levels in IDDM patients at the initiation of insulin therapy (IDDM onset) were markedly reduced compared with those in normal controls (334.2 +/- 26.3 ng/ml vs 492.4 +/- 55.5 ng/ml, mean +/- SEM, P = 0.0038). They fell sharply during 6 months before and after the onset of IDDM. The dynamic profile of sHLA and the time course of beta-cell loss were different between IDDM patients with and without HLA-A24. In those with HLA-A24, sHLA became significantly lower than normal controls with HLA-A24 at IDDM onset. Recovery of their sHLA values occurred at 3 years from IDDM onset. On the other hand, in those without HLA-A24, sHLA levels began to decrease since the onset of IDDM and became significantly lower than normal controls without HLA-A24 at 4 years after the onset. Recovery of sHLA occurred at more than 6 years from the onset. An early (within 18 months), complete loss of beta-cell function occurred in 5 of 13 IDDM patients with HLA-A24 compared with 1 of 14 of those without HLA-A24 (P = 0.077). A late (more than 36 months after the onset of IDDM), complete loss of beta-cell function occurred in 7 of 14 IDDM patients without HLA-A24 but in none of 13 of those with HLA-A24 (P = 0.0058). These results indicate that the decline of sHLA is synchronous with massive beta-cell destruction, and that these events occur during a short period in IDDM patients with HLA-A24, whereas they occur during a relatively long period in those without HLA-A24.

Adolescent↗
PubMed1997

Serum concentrations of soluble HLA-class I and CD8 forms in patients with viral hepatic disorders.

Soluble HLA-class I and CD8 molecules were determined by sandwich ELISA in patients with viral-induced hepatic disorders. As a whole, the patients with hepatic disorders (acute hepatitis: AH; chronic hepatitis: CH; liver cirrhosis: LC; hepatocellular carcinoma: HCC) showed higher sHLA-class I and sCD8 levels than normal controls (P < 0.001). AH patients had the highest sHLA-class I levels (mean, 3513 +/- 2112 ng/ml), followed by CH (2896 +/- 1290 ng/ml), LC (2293 +/- 1266 ng/ml), and HCC (2221 +/- 1212 ng/ml) sCD8 levels wer highest in AH, followed by HCC, LC, and CH, in that order. Among histologically defined C virus-positive patients, sHLA-I levels were higher in those with chronic active hepatitis (CAH) 2A (3802 +/- 1124 ng/ml) than in those with chronic persistent hepatitis (CPH; 2200 +/- 711 ng/ml; P < 0.01), the levels then decreased as the disease progressed (CAH2B, 3564 +/- 1783 ng/ml, LC, 2376 +/- 1265 ng/ml). In contrast, sCD8 values showed little difference among the disorders. sHLA-class I levels showed a positive correlation with sCD8 values both in whole patients and in patients with AH (P < 0.01), but no correlation was shown, in any patients, with biochemical parameters such as GPT and GOT. These findings, taken together, suggest that hepatic destruction is not the only cause of sHLA-class I production, but that sHLA-class I levels, together with sCD8 levels, may reflect immunological activity in hepatic disorders.

CD8 Antigens↗
PubMed1997

HLA-A2 antigen status predicts metastasis and response to immunotherapy in gastric cancer.

Our previous studies have shown that HLA-DR4 and -B52 antigens are associated with an increased risk of lymph node metastasis in patients with gastric cancer. We hypothesized that a putative HLA antigen, correlated with a low risk of lymph node metastasis, may also be correlated with the response to anticancer therapy. The microcytotoxicity assay was used to examine 49 HLA antigens of the A, B, C, DR, and DQ loci, and the association between HLA class I and II antigen status and lymph node metastasis in 847 patients with gastric cancer as well as the response to the therapy in 739 patients were analyzed. HLA-A2 antigen was significantly associated with a low risk of lymph node metastasis in patients with T2-T4 advanced cancer [58.8% compared to 37.0% in patients with lymph node metastasis; corrected P, Pc (98), = 0.011], especially in those with moderately differentiated adenocarcinoma [71.0% compared to 26.4% in patients with lymph node metastasis, Pc (294) = 0.00294] and with a better response to post-operative immunotherapy using protein-bound polysaccharide K (PSK), a nonspecific immunomodulator, than to chemotherapy. HLA alleles may be associated with resistance or susceptibility to lymph node metastasis and HLA-A2 antigen may be a useful predictor of the response to PSK. The data suggest that the predictive power of this HLA antigen may prove useful in the selection of anticancer therapy.

Adenocarcinoma↗
PubMed1997

Alloplasmic wheats with Aegilops crassa cytoplasm which express photoperiod-sensitive homeotic transformations of anthers, show alterations in mitochondrial DNA structure and transcription.

Alloplasmic wheat. Triticum aestivum cv. Norin 26, with Aegilops crassa cytoplasm, shows photoperiod-sensitive cytoplasmic male sterility (PCMS). This alloplasmic line expresses pistillody of anthers only when grown in long-day conditions (> 15 h light). To assess the molecular basis of the PCMS, we carried out Southern and Northern hybridization analyses on mitochondrial DNAs and RNAs isolated from seedlings of alloplasmic lines showing various PCMS phenotypes using probes for twelve mitochondrial genes. All RFLP patterns of mitochondrial DNA from alloplasmic lines greatly differed from those of common wheat, and were slightly changed from those of the parental species, i.e., Ae. crassa. This indicates that nuclear substitutions between related plant species induce structural alterations in the mitochondrial genome. Furthermore, RFLP patterns of (cr)-N61 and FR-mutant probed with coxIII and orf25 were identical with each other, but different from those of the other alloplasmic lines, indicating that the nuclei of N61 and FR-mutant harbor some gene(s) that induces structural alterations of the mitochondrial genome in the coxIII and orf25 regions. The transcription patterns of atp6 and cob in Ae. crassa type were different from those of T. aestivum type. Furthermore, the orf25 transcript in alloplasmic wheats was about 300 nucleotides longer than that of euplasmic lines, including the Ae. crassa pure line, suggesting that transcription patterns of orf25 are associated with recovery from the PCMS phenomenon. These data clearly show the mutual cross-talk between the nuclear genome and chondriome. These observations raise the possibility that the dysfunction of mitochondria caused by the failure of a cooperative control of mitochondrial gene(s) expression influences the pathway of flower morphogenesis, especially in the process that determines organ identity.

Blotting, Northern↗
PubMed1997

Immunohistochemical distribution of surfactant apoprotein-A in congenital diaphragmatic hernia.

The high mortality for congenital diaphragmatic hernia (CDH) has been attributed to a combination of pulmonary hypoplasia and persistent pulmonary hypertension. Recent experimental studies suggest that surfactant deficiency may also contribute to CDH pathophysiology. In this report, the authors immunohistochemically and morphometrically examined whether or not the hypoplastic lungs of CDH are associated with the immaturity of the surfactant system, especially alveolar type II cell function. Nine autopsy cases with CDH were immunohistochemically examined for the expression of surfactant apoprotein, using anti-IgG against human surfactant apoprotein A (SP-A), and the findings were compared with those in a gestational and postnatal age-matched control group. The lung/body weight ratio in the CDH was less than that in the controls (0.010 +/- 0.005 versus 0.021 +/- 0.013, P < .01). The radial alveolar count (RAC) of the CDH cases were also significantly less than that of the control cases (2.10 +/- 0.52 versus 3.48 +/- 0.39, P < .01). In the CDH cases, the RAC of the lung on the affected side were also significantly less than that of the lung on the unaffected side (1.71 +/- 0.34 versus 2.50 +/- 0.26, P < .01). In the immunohistochemical distribution of SP-A, compared with the control cases, the number of SP-A-positive cells on the alveolar septa of the CDH cases decreased in number, and this immunohistochemical reaction was weak even in positive type II cells. In addition, the immunoreaction observed in the alveolar type II cells of the unaffected side lungs in the four CDH cases was stronger than that of the unaffected side lungs. These results suggest that in the lungs of the CDH cases, especially on the affected side, there is a possible delay in both the structural growth and functional maturation or development of SP-A synthesis by alveolar type II cells, and this retardation of the functional maturation in alveolar type II cells is also considered to play a role in postnatal respiratory insufficiency in CDH patients.

Apolipoproteins A↗
PubMed1997

Stability of microcystins from cyanobacteria--IV. Effect of chlorination on decomposition.

Microcystins, the cyclic heptapeptide toxins produced by cyanobacteria such as Microcystis, show tumor-promoting activity through inhibition of protein phosphatases 1 and 2A. They potentially threaten human health, and are increasing the world-wide interest in the health risk associated with cyanobacterial toxins. In this study, the effect of chlorination on the decomposition of microcystins-LR and -RR was examined. The toxins were easily decomposed by chlorination with sodium hypochlorite, and the decomposition depended on the free chlorine dose. In this operation, many reaction products were formed, one of which was determined to be dihydroxymicrocystin formed through the chloronium ion at the conjugated diene of Adda [3-amino-9-methoxy-10-phenyl-2,6,8-trimethyl-deca-4(E), 6(E)-dienoic acid], followed by hydrolysis. Other products may be its stereoisomers and/or regioismers. No noxious products were detected from the chlorination process of microcystin-LR. Although these results suggested that chlorination at an adequate chlorine dose is very effective for the removal of microcystin in raw water, preoxidation of the cell itself with chlorine must be avoided, because it frequently causes toxin release from algae and produce trihalomethanes during water treatment.

Animals↗