Relationship between vitamin D receptor gene polymorphisms (BsmI, TaqI, ApaI, and FokI) and calcium intake on bone mass in young Japanese women

Background

The high prevalence of low bone mass in young women in Japan has emerged as a serious health issue in recent years. Therefore, the aim of the present study was to reevaluate the relationship between genetic and dietary factors, as well as its influence on bone mass in young Japanese women, with particular emphasis on vitamin D receptor (VDR) gene polymorphisms and calcium intake.

Methods

A total of 499 Japanese women aged 20–24 years were enrolled in the study. The bone mass of the calcaneus was assessed using the quantitative ultrasound method and expressed as the osteo sono-assessment index (OSI). VDR gene polymorphisms (BsmI, TaqI, ApaI, and FokI) were analyzed using DNA extracted from saliva. Calcium intake was assessed using the Food Frequency Questionnaire based on food groups (FFQg) and adjusted with the energy intake. Participants were divided into two groups based on the median calcium intake (250 mg/1000 kcal).

Results

Consequently, bone mass was significantly different among the BsmI and TaqI genotypes after adjusting for body mass index (BMI) (p = 0.030 and 0.019, respectively). In addition, the BsmI AA and ApaI GT genotypes showed significant differences in bone mass between the calcium-intake groups, with low OSI in the low-calcium intake group and high OSI in the high-calcium intake group, respectively, even after adjusting for BMI (p = 0.020 and 0.038, respectively).

Conclusions

These findings may prove instrumental in developing a logical approach towards preventing bone loss in young Japanese women.

Effect of Cdx2 Polymorphism on the Relationship between Dietary Calcium Intake and Peak Bone Mass in Young Japanese Women

Studies investigating the effect of the caudal-type homeobox protein 2 (Cdx2) polymorphism in the vitamin D receptor gene and calcium intake on bone mass have shown inconsistent results. This study investigated whether the effect of calcium intake on peak bone mass is affected by Cdx2 polymorphism in young Japanese women. A cross-sectional study of 500 young women was conducted. Dietary intake was assessed by the Food Frequency Questionnaire. The osteo sono-assessment index (OSI), assessed by the qualitative ultrasound method, was used as a bone mass index. The subjects were divided into two groups by the median calcium intake. The OSI was not different among Cdx2 genotypes and between calcium groups (p = 0.960, p = 0.191, respectively). The interaction between calcium and Cdx2 genotypes on the OSI approached significance (GG versus GA and AA genotypes, p = 0.092). The difference in the OSI between calcium groups was significant in the GG genotype (p = 0.028), but not in the GA or AA genotypes (p = 0.501, p = 0.306, respectively). Adjustment for covariates (body mass index and physical activity) did not change the results. In conclusion, the relationship between dietary calcium intake and peak bone mass may vary according to Cdx2 polymorphism.

Liver stiffness measurement using acoustic radiation force impulse elastography in hepatitis C virus-infected patients with a sustained virological response

BACKGROUND

Acoustic radiation force impulse (ARFI) elastography is a non-invasive method for measuring liver stiffness. However, there are no reports evaluating the value of ARFI elastography for liver fibrosis in chronic hepatitis C patients with a sustained virological response (SVR).

AIM

To investigate the diagnostic performance of ARFI elastography for the assessment of liver fibrosis in hepatitis C virus (HCV) infected patients with an SVR.

METHODS

In this prospective study, we enrolled 336 patients: 121 HCV patients with an SVR (44.6% women) and 215 patients with HCV (47.9% women). ARFI elastography measurements of all patients were performed on the same day of liver biopsy.

RESULTS

The diagnostic accuracies, expressed as areas under the receiver operating characteristic curves for ARFI elastography, in HCV patients with an SVR and those in patients with HCV were 0.818 and 0.875 for the diagnosis of significant fibrosis (≥F2), 0.909 and 0.888 for the diagnosis of severe fibrosis (≥F3), and 0.981 and 0.890 for the diagnosis of liver cirrhosis (F4), respectively. The optimum cut-off values for ARFI elastography were 1.26 m/s for ≥F2, 1.31 m/s for ≥F3 and 1.49 m/s for F4 in HCV patients with an SVR. The liver stiffness values were lower in patients with SVR compared with those in patients with HCV at the same stage of fibrosis. The liver stiffness values were affected by the necroinflammatory activity and the time after SVR.

CONCLUSION

Acoustic radiation force impulse elastography is an acceptable method for predicting the severity of fibrosis in patients with hepatitis C virus and a sustained viral response.

Diffusion of Uranium in Compacted Bentonite in the Presence of Carbon Steel

In a high-level waste repository, a carbon steel overpack will be corroded by consuming oxygen trapped in the repository after closure. This will create a reducing environment in the vicinity of repository. Reducing conditions are expected to retard the migration of redox-sensitive radionuclides such as uranium.

The apparent diffusivities of uranium were measured in compacted bentonite (Kunigel VI®, Japan) in contact with carbon steel under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusivities of uranium were 3.5 × 10-14 to 1.1 × 10-13 m2/s under reducing conditions and 9.0 × 10-13 to 1.4 × 10-12 m2/s under oxidizing conditions. There was no significant effect of dry density (1.6 to 1.8 g/cm3) and silica sand (0 or 40%) on the apparent diffusivities.

Since the bentonite pore water would be buffered at a pH between 8 and 9, uranium in the bentonite pore water would probably exist as a neutral hydroxide complex under reducing conditions and as an anioníc carbonate or hydroxide complex under oxidizing conditions. The anion exclusion theory cannot explain the difference of diffusivities between the two conditions. The uranium concentrations in bentonite under oxidizing conditions were one order of magnitude higher than those under the reducing conditions. The uranium concentration in the bentonite pore water under the reducing condition is estimated to be two orders of magnitude lower than that under the oxidizing conditions under the assumption of diffusion in porous media.

Diffusion of Uranium in Compacted Bentonites in the Reducing Condition with Corrosion Products of Iron

In high-level waste repository, a carbon steel overpack will be corroded after closure. This will create a reducing environment in the vicinity of the repository. Reducing conditions are expected to retard the migration of redox-sensitive radionuclides such as uranium.

The apparent diffusion coefficients of uranium were measured in compacted bentonites (Kunigel VI® and Kunipia F®, JAPAN) in contact with carbon steel and its corrosion products under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusion coefficients measured were 10-12 to 10-14 m2/s under oxidizing conditions and 10-13 to 10-14 m2/s under reducing conditions. There were significant effects of redox conditions, dry density (0.8 to 2.0 g/cm3) and montmorillonite contents (60% for Kunigel VI or 100% for Kunipia F) on the apparent diffusion coefficients. The sorption of uranium on corrosion products of iron was smaller than that on montmorillonite. Montmorillonite density could be a good index to explain density dependence of the diffusion coefficients under the reducing conditions. Uranium would diffuse in free pore water with diffusion coefficients greater than 10-13 m2/s in low density bentonites under both redox conditions because the diffusion coefficients depended on sorption coefficients. Since diffusion coefficients were independent of sorption coefficients in high density bentonites where free pore water is scarce, surface diffusion might occur with coefficients were of about 10-13 m2/s.

Diffusion of Cs and Sr in Compacted Bentonites Under Reducing Conditions and in the Presence of Corrosion Products of Iron

In high-level waste repositories, a carbon steel overpack will be corroded by consuming oxygen trapped in the repository after closure. Iron corrosion products are expected to interfere with migration of radionuclides by filling the pore in bentonite and sorbing radionuclides. In this study the apparent diffusion coefficients of cesium and strontium were measured in compacted Na-bentonites (Kunigel VI® and Kunipia F®, JAPAN) contacted with carbon steel and its corrosion products under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusion coefficients of cesium with and without corrosion product were 2.2 to 13 × 10−12 m2/s. The apparent diffusion coefficients of strontium with and without corrosion product were 3.1 to 25 × 10−12 m2/s. There were significant effects of dry density (0.8 to 2.0 g/cm3) and montmorillonite contents (50% for Kunigel V1 or 100% for Kunipia F). The presence of corrosion product decreased the apparent diffusion coefficients of Cs in both bentonites and that of Sr in Kunigel V1, especially at low dry density. This may be due to corrosion product filling the pore in the bentonite, decreasing the free pore size and density for diffusion.

Sorption and diffusion of Eu in sedimentary rock in the presence of humic substance

Sorption and diffusion behaviors of Eu in sedimentary rock in the presence of humic substance were investigated. The sedimentary rock collected from 500 m depth of HDB-6 bore hole at horonobe URL site of Japan and Aldrich humic acid (HA) were used in the present study. Sorption behaviors of Eu and the HA on the sedimentary rocks with and without the rock organic matter (ROM) were elucidated as a function of HA concentration. The HA reduced the sorption of Eu on the rock with the increase of HA. Eu and HA sorption on the rock with the ROM was larger than on the rock after removing the ROM, indicating that the ROM plays an important role on the sorption of Eu and HA. The diffusion of Eu in the presence of HA was examined as a function of HA concentration and molecular weight of the HA (∼150 kDa or below 10 kDa) by means of a reservoir depletion test method with the intact rock core of the sedimentary rock. Depletion of Eu concentration in the reservoir was reduced with the increase of HA concentration. On the other hand, slight depletion of HA concentration in the reservoir was observed, indicating that the larger HA molecule diffused less into the rock. From the depletion curve and in-diffusion profile of Eu in the rock, the effective diffusion coefficient, D e, and distribution coefficient, K d, in the intact system were estimated based on the profile fitting of the diffusion data with the conventional simple diffusion-sorption model. It was elucidated that the HA reduced the K d and D e of Eu in the intact system with the increase of HA. The contribution of the HA with smaller molecular weight to both the Eu sorption and diffusion was examined.

Diffusion and sorption of neptunium(V) in compacted montmorillonite: effects of carbonate and salinity

Diffusion and sorption of radionuclides in compacted bentonite/montmorillonite are key processes in the safe geological disposal of radioactive waste. In this study, the effects of carbonate and salinity on neptunium(V) diffusion and sorption in compacted sodium montmorillonite were investigated by experimental and modeling approaches. Effective diffusion coefficients (De) and distribution coefficients (Kd) of237Np(V) in sodium montmorillonite compacted to a dry density of 800 kg m−3were measured under four chemical conditions with different salinities (0.05/0.5 M NaCl) and carbonate concentrations (0/0.01 M NaHCO3).Devalues for carbonate-free conditions were of the order of 10−10–10−11 m2s−1and decreased as salinity increased, and those for carbonate conditions were of the order of 10−11–10−12 m2s−1and showed the opposite dependence. Diffusion-derivedKdvalues for carbonate-free conditions were higher by one order of magnitude than those for carbonate conditions. Diffusion and sorption behaviors were interpreted based on mechanistic models by coupling thermodynamic aqueous speciation, thermodynamic sorption model (TSM) based on ion exchange, and surface complexation reactions, and a diffusion model based on electrical double layer (EDL) theory in homogeneous narrow pores. The model predicted the experimentally observed tendency ofDeandKdqualitatively, as a result of the following mechanisms; 1) the dominant aqueous species are NpO2+and NpO2CO3−for carbonate-free and carbonate conditions, respectively, 2) the effects of cation excess and anion exclusion result in opposite tendencies ofDefor salinity, 3) higher carbonate in solution inhibits sorption due to the formation of carbonate complexes.

Vitamin D receptor gene polymorphism is associated with chronic periodontitis

Chronic periodontitis (CP) is caused by enhanced resorption of the alveolar bone supporting the teeth and is associated with intraoral inflammation after infection with certain bacteria. The VDR gene polymorphism was reported recently to be deeply related to the occurrence of tuberculosis and infection of chronic hepatitis B virus. This may be interpreted to indicate a close relationship between VDR gene polymorphism and the immunological action, because vitamin D activates monocytes, stimulates cell-mediated immunity, and suppresses lymphocyte proliferation. The purpose of the present study was to clarify whether polymorphisms in VDR gene exons are associated with the incidence of CP. A case-controlled study was performed on a group of 168 unrelated Japanese subjects whose ages ranged from 35 to 65 years. The Taq I polymorphism in the VDR gene was found to be associated significantly with CP (X2=4.48, P=0.034). We performed multiple logistic regression analyses on the TT genotype, which was found to be associated with CP, and on well-recognized risk factors, smoking and diabetes. The odds ratio (OR) for the genotype (TT/Tt) was 2.73 (95% CI 1.11-6.68, P=0.028), being larger than the unadjusted value. This indicates that the VDR gene polymorphism (TT genotype) is a risk factor for CP, independently of smoking and diabetes.

Association of vitamin D receptor gene polymorphism with periodontal diseases in Japanese and Chinese

We examined whether polymorphisms in the vitamin D receptor (VDR) gene are associated with the incidence of adult periodontitis (AP) and early-onset periodontitis (EOP) in case-controlled studies of Japanese and Chinese subjects. Restriction fragment length polymorphisms in the VDR gene detected by digestion with Taq I were found to be significantly associated with the occurrence of AP or EOP, suggesting that the VDR genotype a risk factor for periodontitis.

Genetic polymorphisms of the interleukin-1 gene and early marginal bone loss around endosseous dental implants

Dental implant surgery commonly proceeds in two stages. It is generally accepted that bone loss around implants does not occur at stage-II surgery because implants do not receive mechanical loading. However, early marginal bone loss around implants occasionally does occur during the healing period. Genetic polymorphisms in the interleukin-1 (IL-1) gene have been reported to be important for bone homeostasis and susceptibility to bone disease. We therefore investigated whether the idiopathic early marginal bone loss around implants is related to polymorphisms in the IL-1 gene. We performed a case-control study. Patients demonstrating marginal bone loss around implants at stage-II surgery were designated as the 'marginal bone loss (+)' group and those without bone loss as the 'marginal bone loss (-)' group. Polymorphisms of the IL-1alpha and IL-1beta genes (IL-1A-889, IL-1B-511 and IL-1B+3954) were detected by restriction fragment length polymorphism using NcoI, AvaI and TaqI after polymerase chain reactions. A total of 251 implants were placed in 39 patients. Marginal bone loss was observed in 36 implants. The patients with IL-1B-511 2/2 genotype exhibited a significantly higher occurrence of marginal bone loss than those with IL-1B-511 1/1 or 1/2 genotypes (OR=5.63; 95% CI=1.20-26.42; P=0.033). Multiple logistic regression analyses showed a markedly increased odds ratio (OR=10.86; 95% CI=1.64-71.90) in IL-1B-511 2/2 genotype carriers, while ORs of the other risk factors for bone loss, such as age, smoking status, post-menopausal women and bone quality, remained between 0.44 and 6.20. There was no significant difference in the distributions of the IL-1B+3954 and IL-1 A-889 genotypes between cases and controls. These data suggest that the IL-1B-511 2/2 genotype has a significant association with the incidence of early marginal bone loss around endosseous implants.

Bone morphogenetic protein-4 gene polymorphism and early marginal bone loss around endosseous implants

PURPOSE

At stage II surgery during dental implant treatment, early marginal bone loss around the implant occasionally occurs despite a lack of apparent causal events, and the etiology of this bone loss is unclear. This study was designed to investigate whether the bone morphogenetic protein-4 (BMP-4) genetic polymorphism is associated with early marginal bone loss around implants.

MATERIALS AND METHODS

The BMP-4 polymorphism was detected by restriction fragment length analysis using HphI digestion after polymerase chain reaction. A total of 262 implants were placed in 41 patients, and early marginal bone loss was observed in 25 of the 109 maxillary implants and 14 of the 153 mandibular implants.

RESULTS

In the mandible, the patients with the BMP-4 AV genotype had a significantly higher rate of occurrence of marginal bone loss than those with the BMP-4 W genotype (P = .012). According to multiple logistic regression analyses, the odds ratio of the AV versus the W BMP-4 genotype was 8.106 between patients with and those without bone loss in the mandible (95% CI = 1.30 to 50.51; P = .025).

DISCUSSION

These results suggest that the BMP-4 genetic polymorphism influences early marginal bone loss around implants.

CONCLUSION

While perhaps premature in recommendation, genetic screening before implant surgery may prove to be a very useful aid to consider the risk of implant treatment.

Comparison of 5-fluorouracil and 5-fluoro-2'-deoxyuridine as an effector in radiation-activated prodrugs

The purpose of this study was to clarify whether 5-fluoro-2'-deoxyuridine (FdUrd) is superior to 5-fluorouracil (5-FU) as an effector in the radiation-activated prodrugs which we have been developing. The in vitro cytotoxicity of 5-FU and FdUrd was compared in two murine tumor and four human pancreatic cancer cell lines using a colony assay and in vivo efficacy was compared with SCCVII tumor using a growth delay time assay. FdUrd was slightly more hydrophilic than 5-FU. In vitro, FdUrd was more efficient than 5-FU in two lines, whereas 5-FU was more efficient in two lines and the two drugs were almost equal in efficacy in the remaining two. The concentration to reduce tumor cell survival to 50% after 24-h drug exposure was 5-32 microM for both 5-FU and FdUrd in murine lines, while it was 30-210 microM in human pancreatic cancer cell lines. The difference in relative efficacy of the two drugs among these cell lines could not be attributed to the rate of intracellular uptake of the compounds. FdUrd was less toxic than 5-FU in C3H/He mice, and FdUrd was less efficient than 5-FU in SCCVII tumors in vivo. These results suggest that FdUrd is not necessarily more potent than 5-FU, and development of the FdUrd prodrugs may not necessarily turn out to be fruitful.

Relationship between vitamin D receptor gene polymorphism and periodontitis

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions.

METHODS

Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion.

RESULTS

One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.

Association of calcitonin receptor gene polymorphism with early marginal bone loss around endosseous implants

PURPOSE

This study investigated the relationship between calcitonin receptor (CTR) genotype and buccal marginal bone loss observed at stage II surgery for endosseous implants.

MATERIALS AND METHODS

A total of 237 implants were placed in 35 patients; 89 implants were placed in maxillae and 148 implants in mandibles. The CTR genetic polymorphism was examined by the polymerase chain reaction restriction fragment length polymorphism method.

RESULTS

Patients with the TC genotype were 20 times more likely to suffer buccal marginal bone loss in the mandible than patients with the CC genotype. Furthermore, there were no significant differences in the distribution of age, smoking status, postmenopausal women, and bone quality between patients with and without bone loss in either jaw.

DISCUSSION

These results suggest that the known risk factor for bone loss cannot explain the early marginal bone loss around the implants.

CONCLUSION

Although further genetic research should be conducted, it is suggested that the CTR genetic test could become a useful tool in the planning of treatment before implant surgery and lead to more predictable implant treatment.

Modulation of coordination chemistry in copper(I) complexes supported by Bis[2-(2-pyridyl)ethyl]amine-based tridentate ligands

Structure and physicochemical properties of copper(I) complexes of the tridentate ligands L(2) (N,N-bis[2-(6-methylpyridin-2-yl)ethyl]phenethylamine) and L(3) (N,N-bis[2-(2-pyridyl)ethyl]-beta-methylphenethylamine) have been examined to obtain deeper insights into modulation of the coordination chemistry of copper(I) complexes. [Cu(I)(L(2))(CH(3)CN)](ClO(4)) (2.CH(3)CN) has a distorted tetrahedral geometry, which consists of three nitrogen atoms of the ligand and one nitrogen atom of the bound CH(3)CN. Steric repulsion between the 6-methyl group on the pyridine nucleus of L(2) and the metal ion of the complex prevents the cuprous complex from adaptation to a three-coordinate geometry which must have a shorter Cu-N(pyridine) distance ( approximately 1.88 A). Thus, the four-coordinate copper(I) complex (2.CH(3)CN) with a longer Cu-N bond (1.98 approximately 2.13 A) becomes favorable, resulting in rather strong binding of CH(3)CN to the metal ion. In [Cu(I)(L(3))](ClO(4)) (3), there is a Cu(I)-pi interaction between the cuprous ion and the phenyl group of the ligand sidearm. Such a copper(I)-arene interaction is essentially weak, but is significantly stabilized in complex 3. The methyl group at the benzylic position of L(3)() reduces the degree of freedom of sidearm rotation to make the phenyl group stick on the cuprous ion. Thus, the reactivity of the copper(I) complexes of L(2) and L(3) toward dioxygen is significantly diminished, showing sharp contrast to the high reactivity of the copper(I) complex supported by a similar tridentate ligand L(1) (N,N-bis[2-(2-pyridiyl)ethyl]phenethylamine).

Hyperglycemia in diabetic rats reduces the glutathione content in the aortic tissue

The glutathione redox cycle plays a major role in scavenging hydrogen peroxide (H2O2) under physiological conditions. Recently, we demonstrated that a high glucose concentration in the culture medium reduced the level of H2O2 scavenging activity of human vascular smooth muscle cells (hVSMCs). We also showed that a high glucose concentration reduced the intracellular glutathione (GSH) content and the rate of uptake of cystine, which itself is a rate-limiting factor that maintains the GSH level (FEBS Lett.421: 19-22,1998). In the present study, we investigated whether the hyperglycemic condition in diabetic rats impairs the glutathione content in the aortic tissue in vivo. Wistar rats were divided into the following three groups: streptozotocin-induced diabetic rats (STZ-D, n=7), insulin-treated STZ-D rats (I-STZ-D, n=8), and non-diabetic controls (C, n=7). Fourteen days after streptozotocin injection, the aortic tissue was extracted and the GSH content in the aortic tissue was measured. Furthermore, the relationship between the GSH content in the aortic tissue and blood glucose level in Otsuka Long-Evans Tokushima Fatty (OLETF) rats aged 30 weeks, which developed diabetes spontaneously, was investigated. The GSH content in the aortic tissue of the STZ-D group (0.99+/-0.14 nmol/mg protein) was significantly lower than that of the control group (1.68+/-0.15 nmol/mg protein). Insulin treatment to the diabetic rats restored the GSH content in the aortic tissue (I-STZ-D group; 1.45+/-0.11 nmol/mg protein). Among the 22 Wistar rats, the GSH content in the aortic tissue was negatively correlated with the blood glucose level (r=-0.69, p<0.01, n=22). Among the OLETF rats, a similar negative correlation between the GSH content in the aortic tissue and blood glucose level was seen (r=-0.64, p<0.05, n=10). We demonstrated in vivo that the hyperglycemic condition in STZ-induced diabetic Wistar rats and OLETF rats reduced the GSH content in aortic tissue. This suggested reduced glutathione redox cycle function of aorta.

Experimental and modeling studies on sorption and diffusion of radium in bentonite

The sorption and desorption behavior of radium on bentonite and purified smectite was investigated as a function of pH, ionic strength and liquid to solid ratio by batch experiments. The distribution coefficients (Kd) were in the range of 10(2) to > 10(4) ml g-1 and depended on ionic strength and pH. Most of sorbed Ra was desorbed by 1 M KCl. The results for purified smectite indicated that Ra sorption is dominated by ion exchange at layer sites of smectite, and surface complexation at edge sites may increase Ra sorption at higher pH region. Reaction parameters between Ra and smectite were determined based on an interaction model between smectite and groundwater. The reaction parameters were then used to explain the results of bentonite by considering dissolution and precipitation of minerals and soluble impurities. The dependencies of experimental Kd values on pH, ionic strength and liquid to solid ratio were qualitatively explained by the model. The modeling result for bentonite indicated that sorption of Ra on bentonite is dominated by ion exchange with smectite. The observed pH dependency was caused by changes of Ca concentration arising from dissolution and precipitation of calcite. Diffusion behavior of Ra in bentonite was also investigated as a function of dry density and ionic strength. The apparent diffusion coefficients (Da) obtained in compacted bentonite were in the range of 1.1 x 10(-11) to 2.2 x 10(-12) m2 s-1 and decreased with increasing in dry density and ionic strength. The Kd values obtained by measured effective diffusion coefficient (De) and modeled De were consistent with those by the sorption model in a deviation within one order of magnitude.

Heme-Cu complexes as oxygen-activating functional models for the active site of cytochrome c oxidase

Tri(2-pyridylmethyl)amineCu complex-linked iron meso-tetraphenylporphyine derivatives were prepared to model the active site of cytochrome c oxidase. Exposure to oxygen converted the reduced forms of the complexes to the corresponding stable mu-peroxo species in spite of the presence of three coordination sites, two on the heme and one on the Cu. The oxy forms were characterized spectroscopically. Kinetic analyses of the oxygenation reactions of the reduced forms suggests that preferential O2 binding occurs at the Cu site over the heme. This mechanism is also supported by examination of the redox potentials of the two metal ions. Since the peroxy complexes of the models exhibit a structure similar to that of the previously reported fully-oxidized form, the relevance of the model chemistry to the enzyme reaction is discussed.

Effect of vitamin E on the degradation of hydrogen peroxide in cultured human umbilical vein endothelial cells

Vitamin E reacts with radicals such as lipid peroxyl radical (LOO*) and singlet oxygen ((1)O2), and plays a role in inhibiting lipid peroxidation in cell membranes and preventing the oxidation of low-density lipoproteins (LDL). However, only a few studies have investigated the effect of vitamin E on the degradation of hydrogen peroxide (H2O2). Therefore, we examined the effect of vitamin E on glutathione redox cycle-dependent H2O2 degradation activity in human umbilical vein endothelial cells (HUVEC). Confluent HUVEC were cultured for seven days in media containing various concentrations of vitamin E (alpha-tocopherol). The level of glutathione redox cycle-dependent H2O2 degradation activity and the intracellular glutathione level were determined. HUVEC that had been cultured in the presence of higher concentrations of vitamin E had a higher level of H2O2 degradation activity and a higher intracellular content of the reduced form of glutathione (GSH). Therefore, it is suggested that the vitamin E-induced increase in H2O2 degradation activity in HUVEC results from an increase in intracellular GSH level.

Nitric oxide decreases insulin resistance induced by high-fructose feeding

The effect of nitric oxide (NO) on insulin resistance was studied in high-fructose-fed rats. A sequential hyperinsulinemic euglycemic clamp procedure was employed (insulin infusion rates: 3 and 30 mU/kg BW/min) in 12 high-fructose-fed rats and 12 chow-fed rats while awake. Half of the high-fructose-fed and the chow-fed rats, respectively, were continuously given sodium nitroprusside (SNP, 3 ng/kg BW/min) during the clamp study. Blood glucose was clamped at the fasting level in each rat. Plasma insulin levels during the 3 and 30 mU/kg BW/min insulin infusions were 30 and 400 microU/ml, respectively. Metabolic clearance rate of glucose (MCR) was regarded as an index of whole body insulin action. At both 3 and 30 mU/kg BW/min insulin infusions, high-fructose feeding showed a significant decrease in MCR compared with the chow-fed rats. However, decreased MCRs were stimulated by SNP administration and reached similar levels as the chow-fed rats. SNP infusion did not influence MCRs in the chow-fed rats. Therefore it could be concluded that NO can improve insulin resistance induced by high-fructose feeding.

A Cu(II)-mediated C-H oxygenation of sterically hindered tripyridine ligands to form triangular Cu(II)3 complexes

Two sterically hindered tris-pyridyl methane ligands, tris(6-methyl-2-pyridyl)methane (L1) and bis(6-methyl-2-pyridyl)pyridylmethane (L2), are newly synthesized. Under aerobic conditions, Ln (n = 1 or 2) reacts with CuX2 (X = Cl or Br), oxygenated at the methine position to LnOH or LnOMe. The former alcoholate ligand creates trinuclear Cu(II) complexes [Cu3(X)(LnO)3](PF6)2 [(X, n) = (Br, 1) 1, (C1, 1) 2, (Br, 2) 3, or (C1, 2) 4] in which the alkoxide oxygen atoms bridge copper centers. The crystal structures of 1-4 are presented along with their magnetic susceptibility data. The weak antiferromagnetic coupling between the Cu(II) centers in this trinuclear arrangement is due to weak interaction of the magnetic orbitals (dz2) which are oriented along three alternate sides in a hexagon of the Cu3O3 core in 1-4. Under anaerobic conditions, L1 reacts with CuBr2 to form a square pyramidal complex [CuL1Br2] (9) with the ligand facially capping. [Cu(Br)2(L1OMe)] (10) was obtained after the suspension of 9 in MeOH was stirred under air for 48 h. In the presence of cyclohexene, 9 is converted to [Cu(Br)(L1)]m (m = 1 or 2) 5 quantitatively to give trans- 1,2-dibromocyclohexane, indicating that Br2 is generated during the reaction. The FAB MS spectrum of [18O]-1 prepared by the reaction of L1 with CuBr2 under 18O2 shows that the ligand of [18O]-1 is L1(18O-.) L1(18OH), L1OCD3, and bis(6-methyl-2-pyridyl) ketone were obtained from reaction of L1 with CuBr2 in CD3OD under 18O2. These results indicate that the origins of the O atom in L1OH and L1OMe are O2 and MeOH, respectively. On the basis of these results, a mechanism of the oxygenation of L1 in the present system will be proposed.

Function of poly(ADP-ribose) polymerase in response to DNA damage: gene-disruption study in mice

To elucidate the biological functions of poly(ADP-ribose) polymerase (PARP, [EC 2.4.2.30]) in DNA damage responses, genetic and biochemical approaches were undertaken. By disrupting exon 1 of the mouse PARP gene by a homologous recombination, PARP-deficient mouse embryonic stem (ES) cell lines and mice could be produced without demonstrating lethality. PARP-/- ES cells showed complete loss of PARP activity and increased sensitivity to gamma-irradiation and an alkylating agents, indicating a physiological role for PARP in the response to DNA damage. p53, a key molecule in cellular DNA damage response, was found to stimulate PARP activity and became poly(ADP-ribosyl)ated in the presence of damaged DNA. However, PARP-/- ES cells showed p21 and Mdm-2 mRNA induction following gamma-irradiation, indicating that PARP activity is not indispensable for p21 and Mdm-2 mRNA induction in the established p53-cascade. On the other hand, in a reconstituted reaction system, purified PARP from human placenta suppressed the pRB-phosphorylation activity in the presence of NAD and damaged DNA. Human PARP expressed in E. coli showed a similar effect on pRB-phosphorylation activity of cdk2. These findings suggest a direct involvement of PARP in the regulation of cdk activity for cell-cycle arrest.

High concentration of glucose causes impairment of the function of the glutathione redox cycle in human vascular smooth muscle cells

We demonstrated that high glucose reduced H2O2 scavenge activity in human vascular smooth muscle cells. In the cells exposed to high glucose, the intracellular glutathione content decreased, although the NADPH content was unchanged. The rate of uptake of cystine, which is a rate-limiting precursor of the glutathione synthesis, decreased in the high glucose group compared with the control group. These decreases were shown to be dependent on glucose concentration. It was suggested that high glucose causes impairment of the function of the glutathione redox cycle in human vascular smooth muscle cells, resulting in reduced H2O2 scavenge activity.

Paraoxonase polymorphism (Gln192-Arg) is associated with coronary heart disease in Japanese noninsulin-dependent diabetes mellitus

Serum paraoxonase/arylesterase (PONA) is associated with high-density lipoprotein and may prevent oxidation of low-density lipoprotein by hydrolyzing lipid peroxides. A recent report suggested an association of glutamine (A type)/arginine (B type) polymorphism at position 192 of PONA gene with coronary heart disease (CHD) among Caucasian patients with noninsulin-dependent diabetes mellitus (NIDDM). However, conflicting results have also been reported. To investigate the significance of this polymorphism in the pathogenesis of CHD, we performed an association study of this polymorphism with CHD in Japanese NIDDM patients. We genotyped 164 patients with NIDDM, 42 with CHD, and 122 without CHD. Other known risk factors for CHD were matched between the 2 groups. AB+BB isoforms were detected in 41 of 42 diabetic patients with CHD. The proportion of B allele carriers (AB+BB) was significantly higher than that of AA carriers among diabetic patients with CHD compared with those without CHD (chi 2 = 7.68, P = 0.003). Multivariate logistic regression analyses showed a markedly increased odds ratio (OR: 8.823, CI, 1.13-68.7) in B allele carriers, while ORs of other risk factors remained between 1.01 and 1.92. Carriers of the B allele of the Gln192Arg polymorphism in the PONA gene proved to be at increased risk for developing CHD in Japanese NIDDM patients. This association was independent of other known risk factors for CHD, suggesting an important role of the paraoxonase B isoform in the pathogenesis of CHD.

Absence of association between the Gly40-->Ser mutation in the human glucagon receptor and Japanese patients with non-insulin-dependent diabetes mellitus or impaired glucose tolerance

We investigated whether a G123-->A mutation causing a Gly40-->Ser substitution in exon 2 of the human glucagon receptor gene, which has been reported to be associated with non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) in France and Sardinia with a prevalences as high as 4.6% and 8.3%, respectively, is associated with Japanese patients with glucose intolerance. This mutation was not found in 242 unrelated Japanese patients with NIDDM or 23 with IGT by screening by the polymerase chain reaction-restriction fragment length polymorphism method. We also performed single-stranded conformational polymorphism analysis to search for new mutations in this gene associated with glucose intolerance. We found no mutations by examining all the 13 exons from 30 selected patients with NIDDM who had at least 2 diabetic first-degree relatives. These patients were also screened for the common polymorphism at codon 155 reported previously, but none were found to carry it. The absence of the mutation and polymorphism, which are common in French and Sardinian NIDDM or IGT patients, in Japanese indicates the existence of marked ethnic differences.

Restoration of nitric oxide production by aldose reductase inhibitor in human endothelial cells cultured in high-glucose medium

The effects of elevated glucose and aldose reductase inhibitor (ARI:ONO-2235) on nitric oxide (NO) production in cultured human umbilical endothelial cells (HUVEC) were evaluated. Aldose reductase and nitric oxide synthase(NOS) share NADPH as an obligate cofactor, therefore it is suggested that the enhanced of glucose flux (27.5 mM) by aldose reductase inhibited NO production by blunting NOS activity. However, the addition of ONO-2235 (100 microM) prevented the inhibition of [NO2-] production. Since ARI decreases glucose-mediated inhibition of NO production in HUVEC. this agent might ameliorate endothelial function associated with diabetes.

Increased production of PDGF by angiotensin and high glucose in human vascular endothelium

The mechanisms responsible for the abnormalities in the vascular wall associated with long standing diabetes mellitus are incompletely understood. The aim of this investigation was to assess the effects of angiotensin II and high glucose on the production of platelet-derived growth factor (PDGF) in human endothelial cells. For this purpose, a primary culture was obtained from fresh human umbilical cords by collagenase digestion of the vein interior. A high glucose medium increased the production of PDGF and a similar effect was observed by the addition of mannitol. These data are consistent with a stimulatory effect of glucose on PDGF that is mediated by the osmotic effect of this substance. Angiotensin II significantly increased PDGF in human endothelial cells and the effect was accompanied by a transient increase in cytosolic calcium. The angiotensin II-induced intracellular Ca2+ increases, PDGF production were completely abolished by saralasin and neomycin, respectively. We postulate that the increased production of PDGF by the vascular endothelium in response to high glucose and angiotensin II may participate in the development of the diabetic angiopathy.

[Surgical treatment of a long-term decubitus ulcer]

A 64-year-old male presented with a large decubitus ulcer of the sacrum which had not healed for thirteen years in spite of various conservative treatments. His primary disease was paraplegia following spondylitis. Although he was not ambulatory, he was able to manage a wheelchair. The decubitus, which had a 8 x 13 cm dead space, was successfully closed with a single operation using two fasciocutaneous flaps. The patient was discharged two months postoperatively. The medical cost of his treatment before and after the surgery was investigated. The expense including the surgery and postoperative care until discharge was five times more than the monthly cost of the preoperative period. These findings suggest that a decubitus ulcer which does not respond to conservative treatments for more than several months should be considered for a surgical management, as long as the patient's general condition permits an operation.