Cell cycle of primitive hematopoietic progenitors decelerated in senescent mice is reactively accelerated after 2-Gy whole-body irradiation.

Aging is considered to be a functional retardation of continuous xenobiotic responses over a lifetime after the developmental period; thus, the effects of ionizing radiation over a lifetime may be somewhat accounted for by a modifier of aging effects. This study was conducted to evaluate the possible/synergic effects of radiation during aging by determining cell-cycle parameters of hematopoietic stem cells/hematopoietic progenitor cells (HSCs/HPCs), such as the percent of cells in cycling, the generation doubling time, and the cumulative cycling-cell fraction, by bromodeoxyuridine-ultraviolet assay, which enables the determination of their cycling capacity in vivo. Colony-forming progenitor cells, such as colony-forming unit (CFU)-granulocyte/macrophage (GM), CFU in the spleen on day 9 (CFU-S9), and CFU-S on day 13 (CFU-S13) for mature, less mature, and immature HPCs, respectively, were evaluated in young and old mice (6 weeks and 21 months of age, respectively) with or without 2-Gy whole-body irradiation and a 4-week recovery period. Then, cell-cycle parameters were evaluated and compared. As a result, the generation doubling time of all types of HPC was prolonged by the irradiation in both young and old mouse groups, except that of CFU-S13 in old mice, which showed acceleration of the cell cycle following the irradiation. In addition, only CFU-S13 in irradiated old mice showed a significant increase in the cumulative cycling-cell-fraction ratio. Significant changes due to the effects of aging and irradiation on HPCs were observed only in the immature HPCs, i.e., the cell cycle of immature HPCs was suppressed by aging without irradiation and was, in contrast, accelerated as the cells recovered from radiation-induced damage. This suggests that the mechanisms of peripheral blood recovery after 2-Gy whole-body irradiation are markedly different between young and old mice, although 21-month-old mice showed almost the same level of recovery as the young mice.

Experimentally induced, synergistic late effects of a single dose of radiation and aging: significance in LKS fraction as compared with mature blood cells.

The number of murine mature blood cells recovered within 6 weeks after 2-Gy whole-body irradiation at 6 weeks of age, whereas in the case of the undifferentiated hematopoietic stem/progenitor cell (HSC/HPC) compartment [cells in the lineage-negative, c-kit-positive and stem-cell-antigen-1-positive (LKS) fraction], the numerical differences between mice with and without irradiation remained more than a year, but conclusively the cells showed numerical recovery. When mice were exposed to radiation at 6 months of age, acute damages of mature blood cells were rather milder probably because of their maturation with age; but again, cells in the LKS fraction were specifically damaged, and their numerical recovery was significantly delayed probably as a result of LKS-specific cellular damages. Interestingly, in contrast to the recovery of the number of cells in the LKS fraction, their quality was not recovered, which was quantitatively assessed on the basis of oxidative-stress-related fluorescence intensity. To investigate why the recovery in the number of cells in the LKS fraction was delayed, expression levels of genes related to cellular proliferation and apoptosis of cells in the bone marrow and LKS fraction were analyzed by real-time polymerase chain reaction (RT-PCR). In the case of 21-month-old mice after radiation exposure, Ccnd1, PiK3r1 and Fyn were overexpressed solely in cells in the LKS fraction. Because Ccnd1and PiK3r1 upregulated by aging were further upregulated by radiation, single-dose radiation seemed to induce the acceleration of aging, which is related to the essential biological responses during aging based on a lifetime-dependent relationship between a living creature and xenobiotic materials.

Decreased "ineffective erythropoiesis" preserves polycythemia in mice under long-term hypoxia.

Hypoxia induces innumerable changes in humans and other animals, including an increase in peripheral red blood cells (polycythemia) caused by the activation of erythropoiesis mediated by increased erythropoietin (EPO) production. However, the elevation of EPO is limited and levels return to normal ranges under normoxia within 5-7 days of exposure to hypoxia, whereas polycythemia continues for as long as hypoxia persists. We investigated erythropoiesis in bone marrow and spleens from mouse models of long-term normobaric hypoxia (10 % O2) to clarify the mechanism of prolonged polycythemia in chronic hypoxia. The numbers of erythroid colony-forming units (CFU-E) in the spleen remarkably increased along with elevated serum EPO levels indicating the activation of erythropoiesis during the first 7 days of hypoxia. After 14 days of hypoxia, the numbers of CFU-E returned to normoxic levels, whereas polycythemia persisted for >140 days. Flow cytometry revealed a prolonged increase in the numbers of TER119-positive cells (erythroid cells derived from pro-erythroblasts through mature erythrocyte stages), especially the TER119 (high) CD71 (high) population, in bone marrow. The numbers of annexin-V-positive cells among the TER119-positive cells particularly declined under chronic hypoxia, suggesting that the numbers of apoptotic cells decrease during erythroid cell maturation. Furthermore, RT-PCR analysis showed that the RNA expression of BMP-4 and stem cell factor that reduces apoptotic changes during erythroid cell proliferation and maturation was increased in bone marrow under hypoxia. These findings indicated that decreased apoptosis of erythroid cells during erythropoiesis contributes to polycythemia in mice during chronic exposure to long-term hypoxia.

Lipopolysaccharide reciprocally alters the stromal cell-regulated positive and negative balance between myelopoiesis and B lymphopoiesis in C57BL/6 mice.

Hematopoiesis in the bone marrow (BM) and spleen is controlled by stromal cells. Inflammation promotes myelopoiesis and simultaneously suppresses B lymphopoiesis. However, the role of the reciprocal regulation of myelopoiesis and B lymphopoiesis by stromal cells during inflammation is not fully understood. We investigated inflammation-induced alteration of hematopoietic regulation in lipopolysaccharide (LPS)-treated mice. C57BL/6 female mice were intravenously injected with a single, 5-µg dose of LPS, which induced a rapid decrease in the number of granulocyte-macrophage progenitors (colony-forming unit granulocyte-macrophage; CFU-GM) and B cell progenitors (CFU-preB) in BM. The CFU-GM count rapidly recovered, whereas the recovery of CFU-preB was delayed. LPS induced a marked increase in the number of CFU-GM but not in the number of CFU-preB in spleen. After LPS treatment, gene expression levels of positive regulators of myelopoiesis such as granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in BM and spleen were markedly upregulated whereas levels of positive regulators for B lymphopoiesis such as stromal cell-derived factor (SDF)-1, stem cell factor (SCF), and IL-7 remained unchanged. Meanwhile, the negative regulator of B lymphopoiesis tumor necrosis factor (TNF)-α was markedly up-regulated. The number of CFU-GM in S-phase in BM increased after LPS treatment, whereas the number of CFU-preB in S-phase decreased. These results suggest that LPS-activated stromal cells induce positive-dominant regulation of myelopoiesis and negative-dominant regulation of B lymphopoiesis, which facilitates emergency myelopoiesis during inflammation by suppressing B lymphopoiesis, thereby contributing to the host defense against infection.

Expression of cytokeratin 20 indicates invasive histological phenotype in poorly differentiated colorectal adenocarcinoma.

BACKGROUND/AIM: Cytokeratin (CK) 20 expression is an independent prognostic factor of poorly differentiated adenocarcinoma (PDA) of the colon and rectum. We aimed to investigate the mechanism of its involvement through a clinicopathological study. PATIENTS AND METHODS: We analyzed 156 surgically resected PDAs, which were sub-classified as solid type (Por1) showing expansive growth, or non-solid type (Por2) showing infiltrative growth. Associations of CK20 expression with morphological features and molecular markers were analyzed. RESULTS: CK20(+) PDA (n=91) was associated with more advanced disease stage and unfavorable prognosis compared with CK20(-) PDA (n=65). Pathologically, CK20(+) PDA was significantly associated with p53 overexpression, Por2, abundant fibrous stroma, and stepwise de-differentiation, while CK20(-) PDA was significantly associated with mismatch repair deficiency, Por1, sparse fibrous stroma, and de novo histogenesis. CONCLUSION: CK20 expression in PDA is closely associated with invasive histological features, providing prognostic significance, and may also point to a specific histogenetic pathway.

[Clinical experience of imatinib mesylate for metastatic or recurrent gastrointestinal stromal tumor].

We examined the clinical results of 15 patients treated with imatinib mesylate for metastatic or recurrent gastrointestinal stromal tumors(GIST)at the Osaka City General Hospital. Treatment with imatinib was initiated at 400 mg daily; however, in case of severe adverse events, the dose was gradually reduced to 300 mg or 200 mg to reach a tolerable dose so that administration could be continued for as long as possible. Assessments were performed according to the Response Evaluation Criteria in Solid Tumors(RECIST)and Choi criteria. According to the assessment by the RECIST criteria, clinical response(CR)was observed in 1 patient; partial response(PR), in 5 patients; stable disease(SD), in 6 patients; and progressive disease(PD), in 3 patients; the response rate was 40%. However, as per the Choi criteria, CR was observed in 1 patient; PR, in 11 patients; SD, in 1 patient; and PD, in 2 patients; the response rate was 80%. The median period of progression-free survival was 2,031 days and the 5-year survival rate was 80.0%. Grade 3 or higher adverse reactions observed included leukopenia(1 case), neutropenia( 2 cases), and anemia(1 case). In 6 patients(40%), the dose of imatinib was reduced to 300 mg or less; however, no significant difference in progression-free survival was observed between the 200/300mg group and 400/800mg group. Choi criteria are useful in assessing the response of advanced GIST to imatinib mesylate, and reducing the dose of imatinib mesylate to 200/300mg daily might be sufficient for treating patients who experience severe adverse reactions.

Aberrant cytokeratin expression as a possible prognostic predictor in poorly differentiated colorectal carcinoma.

BACKGROUND AND AIM: The cytokeratin (CK)7(-) /CK20(+) immunoprofile is characteristic of colorectal carcinoma (CRC), although CK7(+) or CK20(-) phenotypes are occasionally encountered, particularly in histologically variant CRCs. We analyzed CK7/CK20 profiles in variant CRCs in association with clinicopathologic parameters and prognosis. METHODS: CK expression in well- and moderately differentiated adenocarcinoma (WMDA) (n = 63), poorly differentiated adenocarcinoma (PDA) (n = 91), mucinous adenocarcinoma (MUA) (n = 81), signet-ring cell carcinoma (SRCC) (n = 15), undifferentiated carcinoma (UDC) (n = 12), and adenosquamous carcinoma (n = 2) was analyzed using immunohistochemistry. Cut-off scores were set at 1% for CK7 and 25% for CK20 using the receiver operating characteristic curve analysis of PDA. Association between CK20(-) and better prognosis in PDA was validated in the second cohort (n = 66). RESULTS: CK7/CK20 immunoprofiling revealed a predominant CK7(-) /CK20(+) profile in WMDA, MUA, and SRCC, while the majority of UDC was characterized by a CK7(-) /CK20(-) profile. The CK7/CK20 profile in PDA was variable. Contingency table analysis revealed that CK expression was not significantly associated with any clinicopathologic parameters in WMDA, PDA, and MUA. However, survival analysis demonstrated that CK20(-) was significantly associated with better prognosis in PDA. Although CK20(-) was significantly associated with mismatch repair deficiency in PDA, it was an independent prognostic factor in multivariate analysis. Finally, we confirmed that CK20 status, determined using a 25% cut-off score, was a significant prognostic parameter in the second PDA cohort. CONCLUSIONS: CK20 status may be used as a prognostic predictor of PDA.

Differential mucin phenotypes and their significance in a variation of colorectal carcinoma.

AIM: To investigate mucin expression profiles in colorectal carcinoma (CRC) histological subtypes with regard to clinicopathologic variables and prognosis. METHODS: Mucin (MUC)2 and MUC5AC expressions were assessed by immunohistochemistry for a total of 250 CRC cases that underwent surgical resection. CRCs included 63 well-to-moderately differentiated adenocarcinomas (WMDAs), 91 poorly differentiated adenocarcinomas (PDAs), 81 mucinous adenocarcinoma (MUAs), and 15 signet-ring cell carcinomas (SRCCs). MUC2 and MUC5AC were scored as positive when ≥ 25% and ≥ 1% of cancer cells were stained positive, respectively. The human mutL homolog 1 and human mutS homolog 2 expressions were assessed by immunohistochemistry in PDAs to investigate mismatch-repair (MMR) status. Tumors that did not express either of these two were considered MMR-deficient. Results were analyzed for associations with clinicopathologic variables and the prognosis in individual histological CRC subtypes. RESULTS: MUC2-positive and MUC5AC-positive WMDA percentages were 49.2% and 30.2%, respectively. In contrast, MUC2-positive and MUC5AC-positive PDA percentages were 9.5% and 51.6%, respectively. MUC2 levels tended to decrease and MUC5AC levels tended to increase from WMDA to PDA. In 21 tumors comprising both adenoma and adenocarcinoma components in a single tumor (4 WMDAs, 7 PDAs, and 10 MUAs), MUC2 was significantly downregulated in PDA and MUC5AC was downregulated in PDA and MUA in the adenoma-carcinoma sequence. These results suggested that MUC2 levels might be associated with malignant potential and that MUC5AC expression was an early event in tumorigenesis. Despite worse prognoses than WMDA, high MUC2 expression levels were maintained in MUA (95.1%) and SRCC (71.5%), which suggested a pathogenesis for these subtypes distinct from that of WMDA. No significant associations were found between MUC2 expression and any clinicopathologic variables in any histological subtype. MUC5AC expression in PDA was closely associated with right-sided location (P = 0.017), absence of nodal metastasis (P = 0.010), low tumor node metastasis stage (P = 0.010), and MMR deficiency (P = 0.003). MUC2 expression in WMDA was a marginal prognostic factor for recurrence/metastasis-free survival (RFS) by univariate Cox analysis (P = 0.077) but not by multivariate Cox analysis (P = 0.161). MUC5AC expression in PDA was a significant prognostic factor for RFS by univariate Cox analysis (P = 0.007) but not by multivariate Cox analysis (P = 0.104). Kaplan-Meier curves and log-rank tests revealed that MUC2 expression was marginally associated with a better WMDA prognosis [P = 0.064 for RFS and P = 0.172 for overall survival (OS)] but not for PDA. In contrast, MUC5AC expression was significantly and marginally associated with a better PDA prognosis in terms of RFS and OS, respectively (P = 0.004 for RFS and P = 0.100 for OS), but not for WMDA and MUA. CONCLUSION: Mucin core protein expression profiles and clinical significance differ according to histological CRC subtypes. This may reflect different pathogeneses for these tumors.

Age-related decline of mast cell regeneration in senescence-accelerated mice (SAMP1) after chemical myeloablation due to senescent stromal cell impairment.

An age-related decline in immune functions is referred to as immunosenescence. Mast cells play an important role in the immune system. However, it has not yet been determined if aging may affect mast-cell development. In the present study, we examined the age-related change in mast-cell development after myeloablation with 5-fluorouracil (5-FU) in senescence accelerated mice (SAMP1), which exhibit senescence-mimicking stromal cell impairment after 30 weeks of age. We found that aged mice with stromal cell impairment (30-36 weeks old) showed a lower recovery of the number of femoral mast-cell progenitors (colony-forming unit [CFU]-mast) (64% of steady state), whereas young mice (8-12 weeks old) showed a higher recovery (122% of steady state). Stromal cells influence mast-cell development by producing positive regulators such as stem cell factor (SCF) and negative regulators such as transforming growth factor-beta (TGF-ß). The ratio of the gene expression of SCF to that of TGF-ß (SCF/TGF-ß ratio) indicates the balance of positive and negative regulation of mast-cell development. SCF/TGF-ß ratio increased in both the young and aged mice after 5-FU treatment. However, the SCF/TGF-ß ratio rapidly decreased in aged mice, whereas it remained high in young mice. The number of femoral CFU-mast in the S-phase after 5-FU treatment reflects the activation of positive-dominant regulation for mast-cell development by stromal cells. Aged mice showed lower recovery of the number of femoral CFU-mast in the S-phase (47% of steady state), whereas young mice showed a higher recovery (205% of steady state). These results suggest that mast-cell development declines with aging due to stromal-cell functional impairment, which contributes to immunosenescence.

[A case of recurrent gastrointestinal stromal tumor with complete response from treatment with reduced dose of imatinib mesylate].

We report a patient who had a complete response by treatment with 200 mg of imatinib mesylate daily for peritoneal recurrences of gastrointestinal stromal tumor(GIST)of the stomach. On March 2007, a 68-year-old woman underwent distal gastrectomy for GIST of the stomach. On May 2007, peritoneal recurrences were recognized on CT scan, and treatment with 400 mg daily of imatinib mesylate was started. Because grade 2 systemic edema and rash developed one week later, the imatinib mesylate dose had to be reduced to 200 mg daily from July 2007. After reduction of imatinib mesylate, the adverse reactions resolved. Peritoneal dissemination disappeared on CT scan from April 2010, and complete response has been maintained for 18 months.

Ovariectomized mouse uterotrophic assay of 36 chemicals.

The concern over endocrine disruptors prompted international establishment of a strategic framework for the identification of the estrogenic compounds. OECD has launched the Conceptual Framework tool box containing various screening and testing methods including the uterotrophic assay. The (anti)estrogenicity of 36 chemicals suspected to be estrogen-receptor interactive by in silico and/or in vitro screening in the Extended Scheme for Endocrine Disruptor Screening and Testing of the Ministry of Health, Labour and Welfare, Japan, were monitored by the uterotrophic assay using C57BL/6J ovariectomized adult female mice after a 7-day exposure by oral gavage (po) and subcutaneous injection (sc). Ethynyl estradiol was used as reference for agonist and antagonist detection. In addition, Bisphenol A (sc) and Genistein (po) were tested for the comparison to rat assays. Among the 36, 2-[Bis(4-hydroxy-phenyl)methyl]benzylalcohol, 2,2',4,4'-Tetrahydroxybenzophenone, 2,4-Dihydroxybenzophenone, 3,3',5-Triiodothyroacetic acid, New fuchsin and alpha-Naphtholbenzein, showed both estrogenic agonistic and antagonistic activities; first two showed U-shaped dose-response in antagonistic studies. N,N-Diphenyl-p-phenylenediamine, 2,2'-Dihydroxy-4,4'-dimethoxybenzophenone, n-Butyl 4-hydroxybenzoate, and Reserpine were agonistic by sc. Benzo [a] pyrene, Benz [a] anthracene, Dibenz [a,h] anthracene, 2-(2H-Benzotriazol-2-yl)-4,6-di(t-pentyl)phenol, Rosemarinic acid, meta-Thymol, 6-Gingerol, Colchicine, Malachite green base, Fenbuconazole, and Lead acetate were antagonistic. The rest, i.e. n-Heptyl 4-hydroxybenzoate, Tetrazolium violet, Pravastatin sodium salt, Physostigmine, salicylate (1:1), Nordihydroguaiaretic acid, o-Cresolphthalein, 1,3-Dinitrobenzene, C.I. Pigment orange, Tetrabromobis-phenol-A, 2-Hydroxy-4-methoxybenzophenone, Ethylparaben, Propyl p-hydroxybenzoate, Kaempferol, 2-(2-Benzotriazolyl)-p-cresol and Phenolphthalein were negative for both effects. Taking together with in silico/ in vitro screening, the result suggested that the ovariectomized mouse uterotrophic bioassay has sufficient performance comparable to rat for the screening of (anti)estrogenicity of various chemicals.

Surface adsorption and vesicle formation of dilauroylphosphatidylcholine in room temperature ionic liquids.

Surface chemical properties of a phospholipid, dilauroylphosphatidylcholine (DLPC), in two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)) and hexafluorophosphate (bmimPF(6)), were investigated by means of surface tension, dynamic light-scattering, and freeze-fracture transmission electron microscopy. It was found that DLPC shows finite solubility in the ILs and spontaneously forms vesicles with size distribution around 400 nm in diameter above the critical vesicular concentration (CVC) of 0.040 wt.% (in bmimBF(4)) and approx. 0.08 wt.% (in bmimPF(6)). Other than the CVC value, anion specificity of the ILs was also seen in the temperature effect on the vesicular aggregation; that is, a temperature-induced reversible aggregation was observed in bmimPF(6), but not in bmimBF(4). The differences in the vesicular stability against the temperature-induced aggregation could be attributed to differences in the interaction between anion species of the ILs and zwitterionic phosphatidylcholine head groups. The apparent molecular area occupied by DLPC at the air/solution interface was estimated to be 0.37 nm(2) in bmimBF(4) and 0.20 nm(2) in bmimPF(6) by applying the Gibbs adsorption equation. These values are much smaller than the molecular area of 0.69 nm(2) reported for the hydrated DLPC bilayer of lamellar liquid-crystalline phase. This result is not consistent with the traditional Gibbs adsorption model, but can be interpreted in terms of a picture for the surface adsorption of soluble amphiphiles proposed by Moroi et al. Differential scanning calorimetric study is also reported regarding the phase transition behavior of DLPC bilayer solvated by the ILs.

Neopterin, inflammation-associated product, prolongs erythropoiesis suppression in aged SAMP1 mice due to senescent stromal-cell impairment.

Anemia induced by inflammation is well known to be more serious in the elderly than in non-elderly adults; however, the reason why this is so remains unclear. Neopterin produced by monocytes during inflammation promotes myelopoiesis but suppresses B-lymphopoiesis and erythropoiesis, by activating stromal cells in mice. Here, age-related changes in the erythropoietic response to neopterin were determined using senescence accelerated mice (SAMP1) with senescence stromal-cell impairment. Intravenous injection of neopterin into young mice (8-12 weeks old) resulted in a decrease in erythroid progenitor cell number in the bone marrow (BM), concomitant with an increase in myeloid progenitor cell number over one week. Intravenous injection of neopterin into aged mice (30-36 weeks old) resulted in a prolonged decrease in erythroid progenitor cell number in the BM over three weeks and a limited increase in myeloid progenitor cell number over one day. Neopterin treatment induced a decrease in serum erythropoietin concentrations in young mice but not in aged mice. The gene expression of tumor necrosis factor α (TNF-α), a negative regulator of erythropoiesis, was up-regulated in the BM of both young and aged mice, and the degree of TNF-α up-regulation was the same in both groups. The gene expression of interleukin (IL)-11, a positive regulator of erythropoiesis, was also up-regulated over one day in both young and aged mice. However, IL-11 gene expression remained up-regulated thereafter in young mice, whereas it was rapidly down-regulated in aged mice. These data suggest that prolonged suppression of erythropoiesis in aged mice may be due to a decrease in the production of positive regulators rather than to an increase in the production of negative regulators. Our combined data suggest that age-related impairment of stromal cells induces serious anemia in the elderly during inflammation.

[Three cases of giant rectal gastrointestinal stromal tumor].

The frequency of rectal gastrointestinal stromal tumor (GIST) is relatively low. We have experienced three cases of giant rectal GIST. Case 1 was treated with sunitinib after imatinib failed by Stevens-Johnson syndrome as neoadjuvant therapy. Case 2 was treated with imatinib as neoadjuvant therapy. These neoadjuvant therapies had no effect on tumor size. All patients underwent an abdominoperineal resection. The mean major axis was 11 .7 cm. Immnohistochemical staining showed that CD34 and KIT were positive. The term of follow-up is short, but no recurrences have been found in all cases. It has been reported that imatinib as neoadjuvant therapy is useful for radical resection in cases of giant rectal GIST. Furthermore, neoadjuvant therapy seems to be one of the treatment options for locally advanced rectal GIST. However, in cases of GIST patients not responding to imatinib, we should perform a surgical resection immediately.

Mast cell development and biostresses: different stromal responses in bone marrow and spleen after treatment of myeloablater, 5-fluorouracil, and inflammatory stressor, lipopolysaccharide.

Mast-cell-development in the bone-marrow (BM) and the spleen is restrictedly controlled by stromal-cells which produce positive-regulators such as stem cell factor (SCF), and negative-regulators such as transforming growth factor-ß (TGF-ß). How the balance between positive- and negative-regulation is achieved or maintained by stromal-cells is not well understood. We intravenously injected 5-fluorouracil (5-FU) and lipopolysaccharide (LPS) into C3H/HeN mice to disrupt mast-cell-development in order to reveal mechanisms of mast-cell-regulation. 5-FU treatment induces a rapid decrease in the number of mast-cell-progenitor (colony-forming unit (CFU)-mast) cells in the BM and spleen, followed by rapid recovery of CFU-mast numbers. Expression of the SCF gene is one-fiftieth the level of that of TGF-ß during the steady-state in BM and spleen. After 5-FU treatment, SCF mRNA levels in the BM markedly increased, approaching TGF-ß mRNA levels, whereas SCF levels in the spleen showed limited oscillations whose increases paralleled those in TGF-ß levels. In contrast, LPS treatment induces a rapid decrease in CFU-mast number in the BM and a rapid increase in of CFU-mast number in the spleen. After LPS treatment, SCF mRNA levels in the BM markedly decreased, whereas SCF levels in the spleen remained unchanged. These results suggest that regulation of mast-cell-development is dominated by negative-signals in the BM and spleen during the steady-state, and, under biostress-conditions such as 5-FU and LPS treatment, the balance between positive- and negative-regulation can be changed in the BM but not in the spleen. The difference in the regulation of mast-cell-development in the BM versus the spleen probably reflects the different roles of tissue-specific stromal-cells.

Aggregation behavior of nonionic surfactants in ionic liquid mixtures.

We investigated the aggregation behavior of polyoxyethylene (POE)-type nonionic surfactants in ionic liquid mixtures composed of 1-ethyl- and 1-hexyl-3-methylimidazolium tetrafluoroborates (emimBF(4) and hmimBF(4), respectively) by means of (1)H NMR chemical shift analysis and dynamic light-scattering measurements. The surfactants do not aggregate in hmimBF(4), whereas they are essentially immiscible with emimBF(4). That is, the surfactants are highly solvophilic to hmimBF(4), while are highly solvophobic to emimBF(4). In mixtures of emimBF(4) and hmimBF(4) micellization was observed. The critical micelle concentration (cmc) decreased and the mean hydrodynamic diameter of micelles, and hence, the micellar aggregation number, increased with increase in mole fraction of emimBF(4) in the ionic liquid mixture. (1)H NMR chemical shift analysis revealed that hmimBF(4) interacts with surfactant molecules preferentially in the ionic liquid mixture through interaction of hexyl groups with the surfactant hydrocarbon chains. The present work demonstrates that solvent quality can be controlled by mixing two ionic liquids to induce self-aggregation of amphiphilic molecules.

Surface adsorption and aggregate formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6).

Surface adsorption and aggregation behavior of polyoxyethylene (POE)-type nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF(6)), were investigated by means of surface tension, (1)H NMR, and dynamic light-scattering (DLS) measurements. The maximum surface excess in bmimPF(6) is much lesser than those observed for aqueous solution, reflecting a much weaker solvophobicity exhibited by the surfactant hydrocarbon chain in the ionic liquid compared with the hydrophobicity experienced in water. Compared with another ionic liquid with different anion species, 1-butyl-3-methylimidazolium terafluoroborate (bmimBF(4)), the surfactant solution in bmimPF(6) brings about higher critical micelle concentration (cmc), smaller micellar aggregation number, and weaker dependence of cmc on the surfactant hydrocarbon chain length. This indicates that the solvophobic interaction between surfactant hydrocarbon chains acts more weakly in bmimPF(6) than in bmimBF(4). The weaker solvophobic effect in bmimPF(6) is also appreciable in the thermodynamic parameters for micelle formation derived from temperature dependence of cmc, and would be attributed to weaker attractive interaction between bmim cation and PF(6)(-) ion compared with that between bmim cation and BF(4)(-) ion. Present results give an insight into a better understanding of the importance of anion species for the properties of ionic liquids as a solvent to support a self-assembly of amphiphilic molecules.

Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect.

The low-dose issue and stochastic responses to endocrine disruptors.

The impact of endocrine disruptors, and specifically the low-dose issue, involves interdisciplinary sciences. Thus, in the past these topics have been published widely in the toxicology area. Owing to recent developments in biology, including the whole-genome reading program, the mechanisms underlying the low-dose issue have been clarified. These mechanisms have been found to involve stochastic and probabilistic receptor-mediated adverse effects induced by endocrine disruptors. The effects thought to be induced by low doses of endocrine-disrupting chemicals remain disputed, and the underlying mechanisms remain poorly understood. Three independent factors, each only recently identified and never before encountered in the history of toxicological studies, are associated with what is termed the 'low-dose issue'. First, toxicological risk has been estimated only by extrapolation of adverse phenotypes from high-dose effects and thus provides no reliable information on low-dose effects observed at the right time under experimental paradigm with sufficient sensitivity. Second, toxicity is based on disturbances of homeostatic regulation, a largely unexplored area in toxicology. Third, toxicity is based on stochastic and probabilistic xenobiotic response, a new field of toxicology that is specifically linked to low-dose and less-frequent events. To resolve the low-dose issue whether it causes effects or whether effects observed at low-doses should be considered 'adverse'--or both, each of these factors needs to be addressed.