Yuji Morimoto

Common Defects of ABCG2, a High-Capacity Urate Exporter, Cause Gout: A Function-Based Genetic Analysis in a Japanese Population

Dysfunctional genotype combinations of polymorphic adenosine 5′-triphosphate–binding cassette transporter gene ABCG2/BCRP, which encodes a high-capacity urate secretion transporter in human gut and kidney, are major causes of gout. Gout, the “Disease of Kings” as it is often known, is a painful medical condition characterized by sharp acute pain in bone joints, due to the high deposition of uric acid crystals from the blood serum into the surrounding cartilage. It affects approximately 1% of the U.S. population and remains a significant public health concern. The prevalence of gout is much higher in certain Asian ethnic groups, and is also reportedly rising in African Americans. Current medical treatments are aimed at ameliorating pain severity, but as the underlying genetic etiology of the disease unfolds, new targets for future therapies are likely to be found. Although genome-wide association studies (GWAS) have enabled the calculation of risk predispositions for a wide variety of complex diseases, the relation of gene function to the causality of disease-related mutations has remained largely unclear. A recent U.S. population–based study supported an association between urate levels and gout in individuals carrying variants in a multifunctional transporter gene, ABCG2. This study identified Q141K as a high-risk variant in nearly 10% of gout cases in Caucasians. Now, a team led by Hirotaka Matsuo report that in a Japanese population, another risk variant in ABCG2, namely the Q126X nonfunctional mutation, confers an even higher risk associated with an increase in uric acid deposition in the blood and may cause gout in Asians. Because this gene is responsible for giving rise to a protein that transports harmful waste products and metabolites out of the kidney and gut, they extensively validate the biological activity of ABCG2 using functional assays in vitro that effectively recapitulate human data obtained from Japanese individuals afflicted with the disease. These findings lend weight to previously reported GWAS; moreover, these newly identified specific high-risk variants that block urate secretion may serve as potential intervention points for quelling the disease. Gout based on hyperuricemia is a common disease with a genetic predisposition, which causes acute arthritis. The ABCG2/BCRP gene, located in a gout-susceptibility locus on chromosome 4q, has been identified by recent genome-wide association studies of serum uric acid concentrations and gout. Urate transport assays demonstrated that ABCG2 is a high-capacity urate secretion transporter. Sequencing of the ABCG2 gene in 90 hyperuricemia patients revealed several nonfunctional ABCG2 mutations, including Q126X. Quantitative trait locus analysis of 739 individuals showed that a common dysfunctional variant of ABCG2, Q141K, increases serum uric acid. Q126X is assigned to the different disease haplotype from Q141K and increases gout risk, conferring an odds ratio of 5.97. Furthermore, 10% of gout patients (16 out of 159 cases) had genotype combinations resulting in more than 75% reduction of ABCG2 function (odds ratio, 25.8). Our findings indicate that nonfunctional variants of ABCG2 essentially block gut and renal urate excretion and cause gout.

Acute brain swelling after out-of-hospital cardiac arrest: pathogenesis and outcome.

ObjectivesFirst, to examine factors that may be related to brain swelling, which was identified by the absence or compression of the lateral and third ventricles and perimesencephalic cisterns on brain computed tomography (CT) scans in the early postresuscitation period in patients who suffered an out-of-hospital cardiac arrest. Second, to characterize the neurologic outcome in those patients in whom cardiac arrest was followed by brain swelling. DesignProspective and retrospective analyses. SettingsGeneral ICU, tertiary care hospital. PatientsFifty-three patients (35 male, 18 female) who had an out-of-hospital cardiac arrest and who also had a brain CT examination on the third day after resuscitation. The 53 patients were divided into two groups: group A (25 patients) experienced brain swelling on postresuscitation day 3; group B (28 patients) did not experience noticeable brain swelling. InterventionsNone Measurements and Main ResultsThere was a significant difference between the two groups in the etiology of the cardiac arrest. Twenty-three of 25 patients in group A had cardiac arrest due to respiratory distress, whereas this finding was true in only five patients in group B. In laboratory data, arterial pH was significantly lower in group A than in group B (6.93 vs. 7.09), as was base deficit (-21.0 mmol/L in group A vs. −13.7 mmol/L in group B). Neurologic outcome was evaluated 1 wk after resuscitation. There were significantly more patients in group A who were not awake and who were diagnosed as braing dead. ConclusionsThe cause of brain swelling may be related to the development of the metabolis acidosis (possibly lactic acidosis) due to hypoxie before the resuscitation period. Brain swelling may be one of the indicators that predicts a poes neurologic outcome in the patients who suffes an out-of-hospital cardiac arrest. (Crit Care Med 1993; 21:104–110)

Vascularization in vivo caused by the controlled release of fibroblast growth factor-2 from an injectable chitosan/non-anticoagulant heparin hydrogel

Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel. In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo. The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse. When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site. These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs.

Intraoperative lymphography using indocyanine green dye for near-infrared fluorescence labeling in lymphedema

A new method for easy detection of functional lymphatic vessels in the superficial layer is reported. In a clinical trial, lymphography using indocyanine green dye for near-infrared fluorescence labeling in lymphaticovenular anastomoses was performed in 5 patients with lymphedema. The technique is simple and enables a minimally invasive operation to be performed. The results indicate that this technique is useful for acceptance as one of the examinations to evaluation of lymphedema.

Enhanced photodynamic cancer treatment by supramolecular nanocarriers charged with dendrimer phthalocyanine.

Photodynamic therapy (PDT) is a promising method for the localized treatment of solid tumors. In order to enhance the efficacy of PDT, we have recently developed a novel class of photosensitizer formulation, i.e., the dendrimer phthalocyanine (DPc)-encapsulated polymeric micelle (DPc/m). The DPc/m induced efficient and unprecedentedly rapid cell death accompanied by characteristic morphological changes such as blebbing of cell membranes, when the cells were photoirradiated using a low power halogen lamp or a high power diode laser. The fluorescent microscopic observation using organelle-specific dyes demonstrated that DPc/m might accumulate in the endo-/lysosomes; however, upon photoirradiation, DPc/m might be promptly released into the cytoplasm and photodamage the mitochondria, which may account for the enhanced photocytotoxicity of DPc/m. This study also demonstrated that DPc/m showed significantly higher in vivo PDT efficacy than clinically used Photofrin (polyhematoporphyrin esters, PHE) in mice bearing human lung adenocarcinoma A549 cells. Furthermore, the DPc/m-treated mice did not show skin phototoxiciy, which was apparently observed for the PHE-treated mice, under the tested conditions. These results strongly suggest the usefulness of DPc/m in clinical PDT.

Novel lymphography using indocyanine green dye for near-infrared fluorescence labeling.

Lymphedema is known to be caused by many pathologic conditions; however, its diagnostic and therapeutic strategies remain to be unestablished. In this study, we investigated the usefulness of a novel lymphographic method based on fluorometric sensing using indocyanine green (ICG) dye for imaging lymphatic vessels using rat models. The real-time imaging system enabled visualization of superficial lymphatic vessels with a diameter of 0.1 mm in 33 frames/second. In addition, morphologic changes in lymphatic vessels in a radiation-induced lymphedema model were detected even at the latent stage. These results suggest that this imaging technique is acceptable as an evaluation method for the lymphatic system.

Chitosan hydrogel as a drug delivery carrier to control angiogenesis

An aqueous solution of photocrosslinkable chitosan containing azide groups and lactose moieties (Az-CH-LA) incorporating paclitaxel formed an insoluble hydrogel within 30 s of ultraviolet light (UV) irradiation. The chitosan hydrogel showed strong potential for use as a new tissue adhesive in surgical applications and wound dressing. The fibroblast growth factor (FGF)-2 molecules retained in the chitosan hydrogel and in an injectable chitosan/IO4-heparin hydrogel remain biologically active, and were gradually released from the hydrogels as they biodegraded in vivo. The controlled release of biologically active FGF-2 molecules from the hydrogels caused induction of angiogenesis and collateral circulation occurred in healing-impaired diabetic (db/db) mice and in the ischemic limbs of rats. Paclitaxel, which is an antitumor reagent, was also retained in the chitosan hydrogel and remained biologically active as it was released on degradation of the hydrogel in vivo. The chitosan hydrogels incorporating paclitaxel effectively inhibited tumor growth and angiogenesis in mice. The purpose of this review is to describe the effectiveness of chitosan hydrogel as a local drug delivery carrier for agents (e.g., FGF-2 and paclitaxel) to control angiogenesis. It is thus proposed that chitosan hydrogel may be a promising new local carrier for drugs such as FGF-2 and paclitaxel to control vascularization.

Tissue factor production not balanced by tissue factor pathway inhibitor in sepsis promotes poor prognosis.

ObjectiveTo determine the precise relationship among tissue factor, tissue factor pathway inhibitor (TFPI), and neutrophil elastase in sepsis, as well as to test the hypothesis that low TFPI concentrations are not sufficient to prevent tissue factor-dependent intravascular coagulation, leading to multiple organ dysfunction syndrome and death. DesignProspective, cohort study. SettingGeneral intensive care unit of tertiary care emergency department. PatientsThirty-one consecutive patients with sepsis, classified as 15 survivors and 16 nonsurvivors. Ten normal, healthy volunteers served as controls. InterventionsNone. Measurements and Main ResultsTissue factor antigen concentration (tissue factor), TFPI, neutrophil elastase, and global variables of coagulation and fibrinolysis were measured on the day of diagnosis of sepsis, severe sepsis, and septic shock and days on 1–4 after diagnosis. The number of systemic inflammatory response syndrome criteria that patients met and the disseminated intravascular coagulation score were determined simultaneously. The results of these measurements were compared between the survivors and the nonsurvivors. In the nonsurvivors, significantly higher concentrations of tissue factor and neutrophil elastase were found compared with the survivors and control subjects. However, the TFPI values showed no difference between the two groups. No correlation was found between the peak concentrations of tissue factor and TFPI. Disseminated intravascular coagulation scores and numbers of the SIRS criteria met by the survivors significantly decreased from day 0 to day 4, but those of the nonsurvivors did not improve during the study period. The nonsurvivors showed thrombocytopenia and higher numbers of dysfunctioning organs than did the survivors. ConclusionsWe systematically elucidated the relationship between tissue factor and TFPI in patients with sepsis, severe sepsis, and septic shock. Activation of tissue factor-dependent coagulation pathway not adequately balanced by TFPI has important roles in sustaining DIC and systemic inflammatory response syndrome, and it contributes to multiple organ dysfunction syndrome and death. High concentrations of neutrophil elastase released from activated neutrophils may explain, in part, the imbalance of tissue factor and TFPI in sepsis.

Systemic activation of tissue-factor dependent coagulation pathway in evolving acute respiratory distress syndrome in patients with trauma and sepsis.

BACKGROUND Extravascular coagulation and fibrin deposition coupled with perturbations of intravascular coagulation occurs in association with acute respiratory distress syndrome (ARDS). To evaluate the pathogenetic role of an extrinsic coagulation pathway in the intravascular coagulation of ARDS patients and to explore the time course of the changes of tissue factor levels, platelet counts, and disseminated intravascular coagulation (DIC), we performed a prospective cohort study. METHODS The study subjects consisted of 113 patients: 27 patients with ARDS, 31 patients at risk for but not developing the syndrome, and 55 patients without ARDS. According to the underlying disease, the patients were further subdivided into two groups: patients with trauma (n = 76) and patients with sepsis (n = 37). Ten normal healthy volunteers served as control subjects. Plasma tissue factor antigen (tissue factor) levels and platelet counts were measured on the day of admission and on days 1 through 4 after admission. Simultaneously, the DIC scores were determined. RESULTS The values of tissue factor in the patients with ARDS were significantly more elevated than those measured in the other two groups (p < 0.001) and control subjects (p < 0.001) on the day of admission. The values continued to be markedly high up to day 4 of admission. On the day of admission, the platelet counts in the ARDS patients showed significantly lower values (p < 0.05) than those in the other two groups. The incidence of DIC and the DIC scores in ARDS patients were significantly higher than those in the other two groups. The tissue factor levels (r(s) = 0.428, p < 0.0001) and DIC scores (r(s) = 0.357, p < 0.0002) correlated significantly with Lung Injury Score. When the patients were subdivided into two subgroups, i.e., trauma and sepsis, some differences of the tissue factor levels were noted between the two groups. CONCLUSION We demonstrated that tissue-factor dependent coagulation pathway of plasma is extensively activated in patients with ARDS, followed by intravascular coagulation and platelet consumption. We further provide precise information on the time course of tissue factor levels and DIC in patients with ARDS and those at risk for developing this syndrome.

Disulfide crosslinked polyion complex micelles encapsulating dendrimer phthalocyanine directed to improved efficiency of photodynamic therapy

Dendrimer phthalocyanine (DPc)-loaded polyion complex micelle (DPc/m) has been developed as photosensitizer (PS) formulation in photodynamic therapy (PDT). Incorporation of DPc into the micelle showed significant enhancement in the in vitro photocytotoxicity. Also, introduction of disulfide crosslinking in the micellar core further improved the in vitro PDT effect of DPc/m. Here, we aim to analyze the mechanism of the enhanced photocytotoxicity of DPc/m, particularly focusing on the photochemical reactions during photoirradiation. As a result, DPc/m has been shown to protect DPc from photobleaching induced by the reactions with serum proteins, although DPc were considerably quenched in the micellar core. Furthermore, the introduction of disulfide crosslinking into the micellar core has demonstrated to improve the efficiency of reactive oxygen species (ROS) production by DPc in the micellar core as well as more effectively prevent the photobleaching of DPc. These effects might lead to effective photochemical reactions by DPc/m, which may account for the enhanced photocytotoxicity. Our findings provide useful knowledge in designing PS formulations for effective PDT.