Presence of Thrombin-Activatable Fibrinolysis Inhibitor in Helicobacter pylori-Associated Gastroduodenal Disease

Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in the regulation of coagulation and inflammation. In addition to inhibiting the fibrinolytic system, TAFI may also regulate the bradykinin and complement systems. We hypothesized that TAFI also plays a role in defense mechanisms of the gastric mucosa during Helicobacter pylori infection. This study comprised 65 patients with gastroduodenal disorders: 41 patients with H. pylori infection, 13 without, and 11 patients with cured H. pylori infection. The gastric intramucosal concentrations of TAFI were measured by enzyme immunoassay. The gastric levels of TAFI and plasminogen activator inhibitor-1 were significantly increased in patients with H. pylori compared to those without infection or cured H. pylori . The presence of TAFI was detected in gastric mucosal epithelial cells. The concentration of TAFI was correlated with the degree of gastric mucosal atrophy, inflammation, and disease activity. These results show that TAFI is present in the gastric mucosa and that it may play a role in the pathogenesis of H. pylori infection-associated gastroduodenal disorders.     

A new model for predicting time course toxicity of heavy metals based on Biotic Ligand Model (BLM)

A new model for predicting time course toxicity of heavy metals was developed by extending the effective ratio of biotic ligand binding with toxic heavy metals to the total biotic ligand for 50% of test organisms (f₅₀) derived by the Biotic Ligand Model (BLM). BLM has been well-known as a useful model for prediction of heavy metal toxicity. BLM can consider the effect of exposure conditions such as pH and Ca²⁺ on heavy metal toxicity. In addition to the exposure conditions, heavy metal toxicity is strongly dependent on exposure time. In this study, BLM is extended to predict time dependency of heavy metal toxicity by connecting with the concept of primary reaction. The model developed in this study also generates the estimation of the 50% effect concentration (EC₅₀) for toxicologically unknown organisms and heavy metals. Two toxicological and kinetic constants, f_50,0 and k, were derived from the initial value of f₅₀ (f_50,0) and a time constant (k) independent of time. The model developed in this study enables us to acquire information on the toxicity of heavy metals such as Cu, Cd and Co easily.     

Expression of inducible nitric oxide (NO) synthase but not prevention by its gene ablation of hepatocarcinogenesis with fibrosis caused by a choline-deficient, L-amino acid-defined diet in rats and mice.

Expression of inducible nitric oxide synthase (iNOS) and effects of iNOS gene ablation on the hepatocarcinogenesis associated with fibrosis caused by a choline-deficient, L-amino acid-defined (CDAA) diet, were examined in male F344 rats and C57BL/6J wild-type and iNOS-/- mice. Western blot, RT-PCR and immunohistochemical analyses revealed increased expression of iNOS protein and mRNA in the livers of rats and wild-type mice fed a CDAA diet for 12-80 weeks, associated with elevated serum NO(x) and liver nitrotyrosine levels. iNOS-/- mice demonstrated greater liver injury and fibrosis in the early stage than their wild-type counterparts, but this did not significantly affect the incidence and multiplicity of altered foci, adenomas and hepatocellular carcinomas in spite of immunohistochemical iNOS expression in these lesions. Results suggested no major determinant roles of the expressed iNOS in the development of liver tumors caused by the CDAA diet.     

Novel emission properties of melem caused by the heavy metal effect of lanthanides(III) in a LB film.

A novel emissive molecular system is constructed by the intercalation of the fluorophore melem (triamino-tri-s-triazine) within a Langmuir-Blodgett (LB) film of stearic acid with the periodic arrangement of lanthanides (Ln(III)), mainly Pr(III) with supporting of Eu(III). From emission spectra, decay curves, quantum yields and XPS measurements, it is clarified that the external heavy metal effect of Pr(III) on melem is much stronger in the film than in the bulk solid state, resulting in producing an unusual triplet state of melem. The triplet state of melem in the LB film donates the excitation energy to Pr(III) in the LB film, which is completely different from the energy transfer pathway of Pr-melem complex in the solid state through the singlet state of melem.     

AP-1-independent sensitization to oxidative stress-induced apoptosis by proteasome inhibitors

Hydrogen peroxide (H(2)O(2)) induces apoptosis of mesangial cells via c-Jun N-terminal kinase (JNK)-activator protein-1 (AP-1) and extracellular signal-regulated kinase (ERK)-AP-1 pathways. We recently found that subtoxic doses of proteasome inhibitors, MG132 and lactacystin, dramatically enhanced H(2)O(2)-induced apoptosis in mesangial cells. In this report, we examined molecular mechanisms involved in this phenomenon, especially focusing on AP-1 pathways. Reporter assays showed that MG132 induced activation of AP-1. However, pharmacological inhibitors of AP-1, retinoic acid, and curcumin, did not suppress the proapoptotic effect of MG132. Suppression of JNK-AP-1 by transfection with either a dominant-negative mutant of JNK or a dominant-negative mutant of c-Jun did not attenuate the apoptosis enhancement by MG132. Similarly, suppression of ERK-AP-1 by PD98059 or dominant-negative mutants of ERK did not affect the apoptosis-promoting effect of MG132. Interestingly, pretreatment with MG132 did not enhance activation of AP-1 by H(2)O(2). These data suggested a novel, AP-1-independent promotion of apoptosis by proteasome inhibitors.     

Involvement of telomere dysfunction in the induction of genomic instability by radiation in scid mouse cells

To determine the effects of a defect in NHEJ on the induction of genomic instability by radiation, we investigated X-ray-induced delayed chromosomal aberrations such as dicentrics and fragments in scid mouse cells. We found that radiosensitive scid mouse cells are more susceptible than wild-type mouse cells to the induction of delayed chromosomal aberrations when the cells are exposed to an equivalent survival dose of X-rays. Telomere FISH analysis revealed that radiation enhances the induction of telomeric fusions where telomeric sequences remain at the fused position (tel+ end-fusions), suggesting that radiation induces telomere dysfunction. Moreover, formation of the tel+ end-fusions was found to be enhanced in scid mouse cells, suggesting that DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a role in telomeric stabilization. Thus, the present study suggests that a cause of genomic instability is telomere dysfunction induced by radiation and that a defect in DNA-PKcs enhances the telomeric destabilization.     

Hypotonic buffer induces meiosis and formation of anucleate cytoplasmic islands in the egg of the two-spotted cricket Gryllus bimaculatus

In insects, egg activation is known to occur in vivo and independently of fertilization, but its mechanisms are poorly understood. To gain understanding of these mechanisms, an attempt was made to activate the egg of Gryllus bimaculatus in vitro. It was found that meiosis resumed and was completed in unfertilized eggs treated with hypotonic buffer. Early developmental processes in activated, unfertilized eggs were investigated and compared with those in fertilized eggs. Mitosis did not progress, resulting in formation of anucleate cytoplasmic islands (pseudoenergids). Development in the activated, unfertilized eggs stopped at this stage and both yolk subdivision and cellularization did not occur. To elucidate the role of the nucleus in the developmental process to the syncytial stage in fertilized eggs, eggs were treated with aphidicolin to inhibit DNA polymerization. It was found that pseudoenergids also formed in these aphidicolin-treated fertilized eggs. These results demonstrate that pseudoenergids can increase in number independently of nuclei, suggesting that the cytoplasm rather than the nucleus plays the primary role in development to the syncytial stage in G. bimaculatus.     

A small deletion hotspot in the type II keratin gene mK6irs1/Krt2-6g on mouse chromosome 15, a candidate for causing the wavy hair of the caracul (Ca) mutation

A new mutation has arisen in a colony of mice transgenic for human alpha-galactosidase. The mutation is independent of the transgenic insertion, autosomal dominant, and morphologically very similar to the classical wavy coat mutation, caracul (Ca), on chromosome 15. Therefore, we designated this locus the caracul Rinshoken (Ca(Rin)). Applying a positional cloning approach, we identified the mK6irs1/Krt2-6g gene as a strong candidate for Ca(Rin) because among five Ca alleles examined mutations always occurred in the highly conserved positions of the alpha-helical rod domain (1A and 2B subdomain) of this putative gene product. The most striking finding is that four independently discovered alleles, the three preexistent alleles Ca(J), Ca(9J), Ca(10J), and our allele Ca(Rin), all share one identical amino acid deletion (N 140 del) and the fifth, Ca(medJ), has an amino acid substitution (A 431 D). These findings indicate that a mutation hotspot exists in the Ca locus. Additionally, we describe a Ca mutant allele induced by ENU mutagenesis, which also possesses an amino acid substitution (L 424 W) in the mK6irs1/Krt2-6g gene. The identification of the Ca candidate gene enables us to further define the nature of the genetic pathway required for hair formation and provides an important new candidate that may be implicated in human hair and skin diseases.     

Closing the (Ran)GAP on segregation distortion in Drosophila

Segregation Distorter (SD) is a meiotic drive system in Drosophila that causes preferential transmission of the SD chromosome from SD/SD(+) males owing to induced dysfunction of SD(+) spermatids. Since its discovery in 1956, SD and its mode of action have baffled biologists. Recently, substantial progress has been made in elucidating this puzzle. Sd, the primary gene responsible for distortion encodes a mutant RanGAP, a key protein in the Ran signaling pathway required for nuclear transport and other nuclear functions. The mutant protein is enzymatically active but mislocalized to nuclei, which apparently disrupts Ran signaling by reducing intranuclear Ran-GTP levels. Some evidence suggests that a defect in nuclear transport may be the main cause of sperm dysfunction. Although important questions remain, the basic mechanism of distortion is now understood sufficiently well that specific hypotheses can be formulated and tested. This previously mysterious genetic system may now offer unique insights into novel aspects of regulation by Ran.     

A disposable biosensor employing a glucose-sensitive biochemomechanical gel

A novel approach to construct a disposable biosensor is proposed. By immobilizing glucose oxidase in a pH-sensitive copolymerized poly(N-isopropylacrylamide)/acrylic acid gel, a glucose-sensitive gel can be obtained. When the gel makes contact with a sample solution containing glucose, the pH of the gel decreases as a result of the enzymatic reaction, inducing the collapse of the gel. The response time to the shrinkage depended upon the activity of the enzyme and the concentration of glucose, although the final ratio of shrinkage settled to approximately the same value irrespective of the concentration of glucose. The transient stage can be used for sensing. The volume change of the gel was transduced into the movement of a colored solution in a flow channel with the help of a silicone rubber diaphragm. The mechanism was used to construct a disposable glucose sensor. A clear dependence of the column length of the colored solution on the concentration of glucose was observed. By measuring the change at a predetermined time, the glucose concentration was obtained. This sensor can be considered the ultimate style in disposable sensors, as detection does not require any electrical measurement or spectroscopic procedures.