Identification of Cadmium Compounds in a Solution Using Graphene-Based Sensor Array

Rapid detection of heavy metals in solution is necessary to ensure human health and environmental protection. Some heavy-metal compounds are present in solution as compounds instead of as ions owing to their low ionization. Therefore, the development of sensor devices for the detection of heavy-metal compounds is important. In this study, as a proof of concept, we propose a sensor device using graphene and a chelating agent, which were used to develop an identification technique for three types of cadmium compounds. Pristine-graphene and two types of chelator-modified graphene-based sensors were successfully used to detect cadmium compounds at concentrations ranging from 50 to 1000 μM. The detection time was less than 5 min. The three type of graphene-based sensors responded differently to each cadmium compound, which indicates that they detected cadmium as a cadmium compound instead of as cadmium ions. Furthermore, we successfully identified cadmium compounds by operating these three types of sensors as a sensor array on the same substrate. The results indicate that sensors that focus on heavy-metal compounds instead of heavy-metal ions can be used for the detection of heavy metals in solution.

Iridium(III)-Catalyzed Asymmetric Site-Selective Carbene C-H Insertion during Late-Stage Transformation

C-H functionalization has recently received considerable attention because C-H functionalization during the late-stage transformation is a strong and useful tool for the modification of the bioactive compounds and the creation of new active molecules. Although a carbene transfer reaction can directly convert a C-H bond to the desired C-C bond in a stereoselective manner, its application in late-stage material transformation is limited. Here, we observed that the iridium-salen complex 6 exhibited efficient catalysis in asymmetric carbene C-H insertion reactions. Under optimized conditions, benzylic, allylic, and propargylic C-H bonds were converted to desired C-C bonds in an excellent stereoselective manner. Excellent regioselectivity was demonstrated in the reaction using not only simple substrate but also natural products, bearing multiple reaction sites. Moreover, based on the mechanistic studies, the iridium-catalyzed unique C-H insertion reaction involved rate-determining asynchronous concerted processes.

Electrical detection of ppb region NO2 using Mg-porphyrin-modified graphene field-effect transistors

The trace detection of NO₂ through small sensors is essential for air quality measurement and the health field; however, small sensors based on electrical devices cannot detect NO₂ with the desired selectivity and quantitativity in the parts per billion (ppb) concentration region. In this study, we fabricated metalloporphyrin-modified graphene field-effect transistors (FETs). Mg-, Ni-, Cu-, and Co-porphyrins were deposited on the graphene FETs, and the transfer characteristics were measured. With the introduction of NO₂ in the ppb concentration region, the FETs of pristine graphene and Ni-, Cu-, and Co-porphyrin-modified graphene showed an insufficient response, whereas the Mg-porphyrin-modified graphene exhibited large voltage shifts in the transport characteristics. This indicates that Mg-porphyrin acts as an adsorption site for NO₂ molecules. An analysis of the Dirac-point voltage shifts with the introduction of NO₂ indicates that the shifts were well-fitted with the Langmuir adsorption isotherm model, and the limit of detection for NO₂ was found to be 0.3 ppb in N₂. The relationship between the mobility and the Dirac-point voltage shift with the NO₂ concentration shows that the complex of NO₂ and Mg-porphyrin behaves as a point-like charge impurity. Moreover, the Mg-porphyrin-modified graphene FETs show less response to other gases (O₂, H₂, acetic acid, trimethylamine, methanol, and hexane), thus indicating high sensitivity for NO₂ detection. Furthermore, we successfully demonstrated the quantitative detection of NO₂ in air, which is near the environmental standards. In conclusion, the results of the Mg-porphyrin-modified graphene FETs enable a rapid, easy, and selective detectability.

Electrical Detection of Molecular Transformations Associated with Chemical Reactions Using Graphene Devices

This study proposes a method to electrically detect chemical reactions that involve bond changes through reactions on graphene surfaces. To achieve a highly sensitive detection, we focused on the thiol-ene reaction that combines the maleimide and thiol groups. Graphene field-effect transistors (FETs) were used to detect the binding changes of the modified molecules. Graphene has high carrier mobility and is sensitive to changes in the electronic state of its surface. Graphene has been used as a sensor to detect low-concentration targets with high sensitivity. N-(9-Acridinyl)maleimide (NAM) was chosen as the modified molecule to immobilize maleimide on graphene through π-interaction, and methanethiol (MeSH) was set as the target thiol. The modification of NAM to graphene was first confirmed by attenuated total reflection Fourier transform infrared spectroscopy, and the modification density was 0.5 ± 0.1/nm² through cyclic voltammetry. Owing to a bond exchange, the transfer characteristics of the graphene FET shifted by 2 V to the negative direction after being exposed to MeSH at 10 parts per billion (ppb), equivalent to 0.2 ng, under ultraviolet irradiation. With 5000 ppb of acetic acid, it only shifted 0.7 V. With 1000 ppb of ethanol and 10,000 ppb of methanol, it shifted to the positive direction by 0.4 and 0.6 V, respectively. Because the nontarget molecule showed only a slight response, a thiol-ene chemical reaction was detected. The proposed method can detect the bond-change reaction using an ultralow concentration of MeSH, which indicates that at least 10 ppb (or 0.2 ng) of MeSH was detected by the graphene FET.

Selective Detection of Cu2+ Ions by Immobilizing Thiacalix[4]arene on Graphene Field-Effect Transistors

Highly accurate quantitative detection of heavy metals is essential for environmental pollution monitoring and health safety. Here, for selective detection of Cu2+ ions with high sensitivity, thiacalix[4]arene (TCA) immobilized on graphene field-effect transistors (G-FETs) are developed. Our proposed TCA-immobilized G-FETs are successfully used to detect Cu2+ ions at concentrations ranging from 1 μM to 1 mM via changes in their transfer characteristics. Moreover, the measured transfer characteristics clearly shift only when Cu2+ ions are introduced in the buffer solution despite it containing other metal ions, including those of Na+, Mg2+, Ni2+, and Cd2+; this selective detection of Cu2+ ions is attributed to the planar arrangement of TCA on graphene. Therefore, TCA-immobilized G-FETs selectively detect Cu2+ with high sensitivity.

Properties of electrostatic correcting systems with annular apertures

Image formation in electron microscopes with circular hole and annular apertures is studied theoretically. The apertures-the circular hole aperture being negative with respect to the annular aperture-produce an additional electrostatic field that exerts a force on the electrons directed toward the optical axis. The resulting deflection angle decreases with increasing distance from the optical axis. This electrostatic field results in a correcting effect of the unavoidable spherical aberration of round electron lenses; the deflection toward the optical axis increases stronger than linearly with increasing distance from the optical axis. Analytical formulae are given for the correcting effect of circular hole and annular apertures. The expressions are based on the Davisson-Calbick formula, which is used to calculate focal length of a simple electrostatic lens.

Photosensing System Using Photosystem I and Gold Nanoparticle on Graphene Field-Effect Transistor

In this study, a light sensor is fabricated based on photosystem I (PSI) and a graphene field-effect transistor (FET) that detects light at a high quantum yield under ambient conditions. We immobilized PSI on a micrometer-sized graphene FET using Au nanoparticles (AuNPs) and measured the I-V characteristics of the modified graphene FET before and after light irradiation. The source-drain current (I_sd) increased upon illumination, exhibiting a photoresponsivity of 4.8 × 10² A W^-1, and the charge neutrality point of graphene shifted by -12 mV. This system represents the first successful photosensing system based on proteins and a solution-gated graphene FET. The probable mechanism of this negative shift can be explained by the increase in negative charge carriers in graphene induced by a hole trap in the AuNP resulting from electron transfer from the AuNP to PSI. Photoresponses were only observed in the presence of two surface-active agents, n-hexyltrimethylammonium bromide and sodium dodecylbenzenesulfonate, because they caused the formation of a hydrophobic environment on the surface of the graphene. The lipid layer of these agents caused dissociation of ascorbate ions from the graphene sheet, thereby expanding the Debye screening length of the electrolyte solution. The hydrophobic environment above graphene also enhanced hole storage in the AuNP through electron transfer from the AuNP to PSI.

Graphene Surface Acoustic Wave Sensor for Simultaneous Detection of Charge and Mass

We have combined a graphene field-effect transistor (GFET) and a surface acoustic wave (SAW) sensor on a LiTaO₃ substrate to create a graphene surface acoustic wave (GSAW) sensor. When a SAW propagates in graphene, an acoustoelectric current (I_A) flows between two attached electrodes. This current has unique electrical characteristics, having both positive and negative peak values with respect to the electrolyte-gate voltage (V_Eg) in solution. We found that I_A is controlled by V_Eg and the amplitude of the SAW. It was also confirmed that the GSAW sensor detects changes of electrical charge in solution like conventional GFET sensors. Furthermore, the detection of amino-group-modified microbeads was performed by employing a GSAW sensor in a phthalate buffer solution at pH 4.1. The hole current peak shifted to the lower left in the I_A-V_Eg characteristics. The left shift was caused by charge detection by the GFET and can be explained by an increase of amino groups that have positive charges at pH 4.1. In contrast, the downward shift is thought to be due to a reduction in the amplitude of the propagating SAW because of an increase in the mass loading of microbeads. This mass loading was detected by the SAW sensor. Thus, we have demonstrated that the GSAW sensor is a transducer capable of the simultaneous detection of charge and mass, which indicates that it is an attractive platform for highly sensitive and multifunctional solution sensing.

Room-temperature discrete-charge-fluctuation dynamics of a single molecule adsorbed on a carbon nanotube

Detection and use of physical noise fluctuations in a signal provides significant advantages in the development of bio- and neuro-sensing and functional mimicking devices. Low-dimensional carbon nanomaterials are a good candidate for use in noise generation due to the high surface sensitivity of these materials, which may themselves serve as the main building blocks of these devices. Here, we demonstrate that the addition of a molecule with high redox activity to a carbon nanotube (CNT) field-effect transistor provides tunable current fluctuation noise. A unique charge-trap state in the vicinity of the CNT surface due to the presence of the single molecule is the origin of the noise, which generates a prominent and unique slow discrete random telegraph signal in the device current. The power spectral density reveals the peculiar frequency limit of the fluctuation for different types of molecules depending on their redox activity and adsorption configuration. These results indicate that the detected noise will provide new opportunities to obtain electronic information for a single molecule combined with a nanotube surface, and that controllability of the noise may contribute to the expansion of noise utilization in future bio-inspired devices.

Inadequate management for secondary fracture prevention in patients with distal radius fracture by trauma surgeons

We evaluated the secondary fracture prevention in 1445 patients with distal radius fracture by trauma surgeons. The rate of patients with distal radius fracture who underwent bone mineral density (BMD) examination was low, suggesting that appropriate treatment for osteoporosis by trauma surgeons is not performed at present.

INTRODUCTION

To clarify the status of osteoporosis interventions after distal radial fractures by trauma surgeons who play the main role in treatment for these fractures, we performed a survey involving multiple institutions in Japan.

METHODS

We asked 155 board members of the Japanese Society for Fracture Repair for their cooperation and performed a survey in 48 institutions with which members who gave cooperation were affiliated. The subjects consisted of consecutive patients with distal radial fractures occurring between January and December 2012. The presence or absence of a diagnosis of osteoporosis and bone mineral density examination after fracture was investigated.

RESULTS

A total of 1445 patients with distal radial fractures were evaluated in this study. BMD examination for diagnosis and treatment for osteoporosis after fracture was performed respectively in 126 (8.7 %) and 193 (13.4 %) of 1445 patients. Treatment for osteoporosis was performed in 93 (73.8 %) of 126 patients who underwent BMD examination after fracture and 100 (8.2 %) of 1219 who did not undergo BMD examination. Of the 126 patients who underwent BMD examination after fracture, 89 showed a BMD <80 % of the young adult mean as a criterion for the initiation of drug treatment for osteoporosis in Japan and 77 (86.5 %) of the 89 patients were treated with drugs.

CONCLUSIONS

The rate of patients with distal radial fractures who underwent BMD examination was low, suggesting that appropriate treatment for osteoporosis by trauma surgeons is not performed at present.

YKL-40 level in gingival crevicular fluid from patients with periodontitis and type 2 diabetes

OBJECTIVE

YKL-40 is a chitin-binding glycoprotein, the level of which increases in inflammatory diseases, diabetes mellitus (DM), cardiovascular diseases, and tumors. Gingival crevicular fluid (GCF) contains many proteins and markers of periodontitis. The purpose of this study was to investigate YKL-40 level in GCF from patients with periodontitis and DM and the association between YKL-40 level and chronic periodontitis (CP) or DM.

SUBJECTS AND METHODS

The subjects were 121 patients with DM, CP, DM and periodontitis (DM-P), and healthy subjects (H). GCF was collected using paper strips after the sites for GCF collection were clinically evaluated for probing depth (PD), gingival index (GI), and bleeding on probing (BOP). YKL-40 in GCF was identified by Western blotting, and its level was determined by ELISA.

RESULTS

YKL-40 was contained in GCF samples from H, DM, CP, and DM-P sites, and its levels (amount and concentration) in CP and DM-P were significantly higher than those in H and DM. GCF YKL-40 level significantly correlated with PD and GI, and its level in BOP-positive sites was significantly higher than that in BOP-negative ones.

CONCLUSIONS

GCF YKL-40 level was elevated in periodontitis, but not DM. YKL-40 in GCF may be an inflammatory marker for periodontitis.

Quantitative evaluation of annular bright-field phase images in STEM

A phase reconstruction method based on multiple scanning transmission electron microscope (STEM) images was evaluated quantitatively using image simulations. The simulation results indicated that the phase shift caused by a single atom was proportional to the 0.6th power of the atomic number Z. For a thin SrTiO3 [001] crystal, the reconstructed phase at each atomic column increased according to the specimen thickness. The STEM phase images can quantify the oxygen vacancy concentration if the thickness is less than several nanometers.

Phase reconstruction in annular bright-field scanning transmission electron microscopy

A novel technique for reconstructing the phase shifts of electron waves was applied to Cs-corrected scanning transmission electron microscopy (STEM). To realize this method, a new STEM system equipped with an annular aperture, annularly arrayed detectors and an arrayed image processor has been developed and evaluated in experiments. We show a reconstructed phase image of graphite particles and demonstrate that this new method works effectively for high-resolution phase imaging.

A schizophrenia risk gene, ZNF804A, is associated with brain white matter microstructure

Genome-wide association studies have provided strong evidence for association of the SNP rs1344706 in the ZNF804A gene with schizophrenia and bipolar disorder. Neuroimaging studies have suggested that variation at rs1344706 may be associated with neural endophenotypes such as white matter volumes and densities. However, analyses of white matter microstructure using diffusion tensor imaging (DTI) have produced conflicting results. We examined the association between rs1344706 and white matter microstructure in 107 healthy individuals using tract-based spatial statistics (TBSS). TBSS analysis showed significant association between the risk allele and lower fractional anisotropy in the corpus callosum, left forceps minor, and right parietal white matter (p<.05; FWE corrected). Post-hoc analyses indicated that this association was largely driven by alterations in radial diffusivity, consistent with an effect of genotype on myelination. In light of the strong DTI evidence for white matter microstructural abnormalities in schizophrenia, the current results implicate a potential mechanism for schizophrenia risk formation by ZNF804A rs1344706 genotype.

[Exposure for harvesting internal mammary artery grafts]

Inflated lungs often disturb the harvesting of internal mammary artery grafts. We employ a Universal Stabilizer Arm and Aortic Valve Assistant (Estech Corporation, Danville) to push the mediastinal pleura and the lung away from the upper part of the mediastinum. This system can be attached to any type of retractor and has excellent flexibility. Its use provides good exposure for harvesting the internal mammary artery.

Development of a parallel detection and processing system using a multidetector array for wave field restoration in scanning transmission electron microscopy

A parallel image detection and image processing system for scanning transmission electron microscopy was developed using a multidetector array consisting of a multianode photomultiplier tube arranged in an 8 x 8 square array. The system enables the taking of 64 images simultaneously from different scattered directions with a scanning time of 2.6 s. Using the 64 images, phase and amplitude contrast images of gold particles on an amorphous carbon thin film could be separately reconstructed by applying respective 8 shaped bandpass Fourier filters for each image and multiplying the phase and amplitude reconstructing factors.

Parry-Romberg syndrome with a clinically silent white matter lesion

We performed a detailed neuroimaging study in a patient with Parry-Romberg syndrome. Proton MR spectroscopy demonstrated normal spectral patterns, though conventional MR imaging revealed high-intensity areas in the entire white matter in the left hemisphere. Single-photon emission tomography showed increased perfusion in the cortex of the affected hemisphere. Pyramidal tracts and optic radiations were preserved on diffusion tensor tractography. We will correlate these neuroimaging findings with normal psychomotor development in our patient.

Transient encephalopathy with reversible white matter lesions in children

We report on two children with acute encephalopathy showing mild clinical manifestations and reversible white matter lesions. In both patients, MRI revealed high intensities on T (2)-weighted imaging and marked reductions of water diffusion in the white matter of the bilateral centrum semiovale and the corpus callosum. These abnormalities disappeared along with the neurological symptoms within a week in both patients. These children represent a characteristic group of patients among childhood acute encephalopathy.

[Redo coronary artery bypass operation under beating heart via the left thoracotomy reusing patent grafts]

We report three cases of successful redo coronary artery bypass grafting (CABG) under beating heart via left thoracotomy with recycling of patent grafts previously implanted. Case 1 and 2: Anginal attack relapsed due to occlusion of the proximal portions of saphenous vein grafts (SVG) that had been sequentially anastomosed to the left coronary artery branches. In each case, the distal portion of the SVG was patent and functioned as coronary-coronary bypass. The left internal thoracic artery graft (ITAG) anastomosed to the left anterior descending coronary artery (LAD) was patent. Each patient underwent off-pump CABG through a left posterolateral thoracotomy. CABG was performed with the radial artery to the circumflex coronary artery (case 1) or the circumflex coronary artery and previous SVG (case 2). The proximal ends of radial artery grafts were anastomosed to the descending aorta. Case 3: Simultaneous reoperative CABG and the operation for the pseudoaneurysm that developed after the abdominal aortic graft replacement were performed. Bypass grafting between ITAG and LAD was performed with SVG via a left anterolateral thoracotomy because of severe anastomotic stricture of ITAG-LAD. The postoperative courses was uneventful for all patients.

Genetic isolates in East Asia: a study of linkage disequilibrium in the X chromosome

The background linkage disequilibrium (LD) in genetic isolates is of great interest in human genetics. Although many empirical studies have evaluated the background LD in European isolates, such as the Finnish and Sardinians, few data from other regions, such as Asia, have been reported. To evaluate the extent of background LD in East Asian genetic isolates, we analyzed the X chromosome in the Japanese population and in four Mongolian populations (Khalkh, Khoton, Uriankhai, and Zakhchin), the demographic histories of which are quite different from one another. Fisher's exact test revealed that the Japanese and Khalkh, which are the expanded populations, had the same or a relatively higher level of LD than did the Finnish, European American, and Sardinian populations. In contrast, the Khoton, Uriankhai, and Zakhchin populations, which have kept their population size constant, had a higher background LD. These results were consistent with previous genetic anthropological studies in European isolates and indicate that the Japanese and Khalkh populations could be utilized in the fine mapping of both complex and monogenic diseases, whereas the Khoton, Uriankhai, and Zakhchin populations could play an important role in the initial mapping of complex disease genes.

Mutation analysis in Rett syndrome

Rett syndrome is an X-linked dominant neurodevelopmental disorder caused by mutations in the MECP2 gene. Mutations have been demonstrated in more than 80% of females with typical features of Rett syndrome. We identified mutations in the MECP2 gene and documented the clinical manifestations in 65 Rett syndrome patients to characterize the genotype-phenotype spectrum. Bidirectional sequencing of the entire MECP2 coding region was performed. We diagnosed 65 patients with MECP2 mutations. Of these, 15 mutations had been reported previously and 13 are novel. Two patients have multiple deletions within the MECP2 gene. Eight common mutations were found in 43 of 65 patients (66.15%). The majority of patients with identified mutations have the classic Rett phenotype, and several had atypical phenotypes. MECP2 analysis identified mutations in almost all cases of typical Rett syndrome, as well as in some with atypical phenotypes. Eleven (20.4%) of the 54 patients with defined mutations and in whom phenotypic data were obtained did not develop acquired microcephaly. Hence, microcephaly at birth or absence of acquired microcephaly does not obviate the need for MECP2 analysis. We have initiated cascade testing starting with PCR analysis for common mutations followed by sequencing, when necessary. Analysis of common mutations before sequencing the entire gene is anticipated to be the most efficacious strategy to identify Rett syndrome gene mutations.

Nano-area electron diffraction pattern reconstructed from three-dimensional Fourier spectrum

A method to obtain a nano-area electron diffraction pattern in transmission electron microscopy (TEM) was proposed, based on three-dimensional (3D)) image formation theory. This method allows us to reconstruct an electron diffraction pattern from a 3D Fourier spectrum of high-resolution through-focus images. As a test case, an electron diffraction pattern from a tilted Si single crystal was reconstructed using the proposed method and compared with the conventional selected-area electron diffraction pattern. The intensity distribution of the reconstructed electron diffraction pattern was confirmed to be qualitatively equal to that of the selected-area electron diffraction pattern, though the degree of the equivalency between these patterns reduces at the high frequency region and the reproducibility of the intensity degrades when the number of images used in the image processing was decreased. By selecting areas in a reconstructed exit wave field, some electron diffraction patterns were obtained from the nano-areas without the influence of spherical aberration.

Effect of tenascin-X together with vascular endothelial growth factor A on cell proliferation in cultured embryonic hearts

Tenascin-X (TNX) is a large glycoprotein that appears in extracellular matrices. Previously, we demonstrated that TNX binds to vascular endothelial growth factors A and B (VEGF-A and -B) and that VEGF-B in combination with TNX induces DNA synthesis in endothelial cells via increased signals mediated by the VEGFR-1 receptor. In this study, we investigated the effect of TNX with VEGF-A on the cell proliferation in embryonic mouse heart explants from either wild-type (TNX+/+) or TNX-deficient (TNX-/-) mice. The addition of VEGF-A to the explants from TNX+/+ mice increased cell proliferation by 1.5 fold compared with that in TNX-/- mice, indicating that TNX with VEGF family member plays an important role in the control of endothelial cell proliferation in vivo.

Wave field restoration using three-dimensional Fourier filtering method

A wave field restoration method in transmission electron microscopy (TEM) was mathematically derived based on a three-dimensional (3D) image formation theory. Wave field restoration using this method together with spherical aberration correction was experimentally confirmed in through-focus images of amorphous tungsten thin film, and the resolution of the reconstructed phase image was successfully improved from the Scherzer resolution limit to the information limit. In an application of this method to a crystalline sample, the surface structure of Au(110) was observed in a profile-imaging mode. The processed phase image showed quantitatively the atomic relaxation of the topmost layer.

Early and long-term results of coronary artery bypass grafting in dialysis patients

OBJECTIVE

We evaluated the surgical outcome of coronary artery bypass grafting in dialysis patients.

METHODS

We retrospectively analyzed 25 consecutive dialysis patients requiring isolated coronary artery bypass grafting. Their mean age was 61.6 years and average dialysis duration 80.4 months.

RESULTS

Eight patients (32%) had emergency or urgent surgery. The mean number of bypassed vessels was 3.3 +/- 1.2. Internal thoracic artery grafts were used in 19 patients and gastroepiploic artery grafts in 5. Two (8%) died during hospitalization and complications occurred in 11 (44%). No cerebral complications were observed. All survivors showed ameliorated symptoms and improved overall function. Of 14 late deaths, 5 were cardiac-related, with 2 involving obvious myocardial ischemic events. Actuarial survival, including hospital deaths, at 1 year was 70.9%, at 3 years was 43.5%, and at 5 years was 34.8%. Cardiac-death-free survival was 70.2% at 3 years and 70.2% at 5 years.

CONCLUSION

Coronary artery bypass grafting in dialysis patients is associated with a higher incidence of complications but has acceptable surgical mortality and effectively relieves angina symptoms.

Dynamic observation of an atom-sized gold wire by phase electron microscopy

A single-atom-sized gold wire was successfully observed in real time by a newly developed defocus-image modulation processing electron microscope. Because of phase retrieval processing with spherical aberration correction, the single-atom strand wire was observed with high contrast and without contrast blurring. By carefully looking at the atomic distance, the contrast, and the dynamic behavior of the wire, we recognized that there are two stages of the wire. In the first stage the wire maintained the atomic distance in the bulk crystal, but in the second stage the wire showed the atomic distance of the nearest-neighbor atoms with weaker contrast. The gold wire was rather stable for a few seconds under strong electron beam illumination.

Rett syndrome from quintuple and triple deletions within the MECP2 deletion hotspot region

Rett syndrome results from mutations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene, which are nearly always lethal in males and lead to regression and reduced life expectancy in females. Herein we report one propositus with five tandem deletions and a second propositus with three tandem deletions within MECP2 exon 4 that encode truncated protein products resulting in classic Rett syndrome. These deletion breakpoints and single deletions in 3 other patients were all found within a 185-bp region along with 64 of 69 other reported deletion breakpoints in the MECP2 gene. Illegitimate recombination resulting in deletion at a substantial proportion of the shared MECP2 sites is enhanced by repeated guanosine (G) DNA sequences in the antisense direction, consistent with reports at other gene loci that polypurine (multiple guanosine or adenosine (A)) basepairs enhance sequence deletion. Multiple deletions at the same poly G recombination sites confirm the existence of deletion hotspots in this gene region with numerous repeated antisense sites that are enriched 26- to 161-fold. Deletion by illegitimate recombination within a single allele can occur during mitotic or meiotic cell cycles. Although prone to disease-causing deletion, this region is unique in humans and highly conserved among mammals for the last 75 000 000 years to maintain the MECP2 gene's critical function.

Mechanism for fetal globin gene expression: Role of the soluble guanylate cyclase-cGMP-dependent protein kinase pathway

Despite considerable concerns with pharmacological stimulation of fetal hemoglobin (Hb F) as a therapeutic option for the beta-globin disorders, the molecular basis of action of Hb F-inducing agents remains unclear. Here we show that an intracellular pathway including soluble guanylate cyclase (sGC) and cGMP-dependent protein kinase (PKG) plays a role in induced expression of the gamma-globin gene. sGC, an obligate heterodimer of alpha- and beta-subunits, participates in a variety of physiological processes by converting GTP to cGMP. Northern blot analyses with erythroid cell lines expressing different beta-like globin genes showed that, whereas the beta-subunit is expressed at similar levels, high-level expression of the alpha-subunit is preferentially observed in erythroid cells expressing gamma-globin but not those expressing beta-globin. Also, the levels of expression of the gamma-globin gene correlate to those of the alpha-subunit. sGC activators or cGMP analogs increased expression of the gamma-globin gene in erythroleukemic cells as well as in primary erythroblasts from normal subjects and patients with beta-thalassemia. Nuclear run-off assays showed that the sGC activator protoporphyrin IX stimulates transcription of the gamma-globin gene. Furthermore, increased expression of the gamma-globin gene by well known Hb F-inducers such as hemin and butyrate was abolished by inhibiting sGC or PKG activity. Taken together, these results strongly suggest that the sGC-PKG pathway constitutes a mechanism that regulates expression of the gamma-globin gene. Further characterization of this pathway should permit us to develop new therapeutics for the beta-globin disorders.

Extracellular matrix tenascin-X in combination with vascular endothelial growth factor B enhances endothelial cell proliferation

BACKGROUND

An extracellular matrix tenascin-X (TNX) is highly expressed in muscular tissues, especially heart and skeletal muscle, and is also prominent around blood vessels. The precise in vivo role of TNX remains to be elucidated. To identify proteins that interact with TNX in the extracellular environment, we searched for TNX-binding proteins using a yeast two-hybrid system.

RESULTS

We used mouse TNX-specific fibronectin type III repeats (mTNX/FNIII13-25) as a bait for the screening. We found that vascular endothelial growth factor B (VEGF-B) binds to mTNX/FNIII13-25. This interaction was confirmed by pull-down assays and co-immunoprecipitation assays. The full-length mTNX, as well as mTNX/FNIII13-25, interacted with both alternative splice isoforms VEGF-B186 and VEGF-B167. Furthermore, the full-length mTNX also bound to VEGF-A. The minimal region of TNX that interacts with VEGF-B was mapped to the FNIII repeats (FNIII13-25) but not to the other characteristic domains of TNX. The TNX-binding site of VEGF-B was located in the N-terminal 115-amino acid region. mTNX/FNIII13-25 did not prevent the interaction of VEGF-B with VEGFR-1 (VEGF receptor 1), and VEGF-B could simultaneously bind to both mTNX/FNIII13-25 and VEGFR-1. A conditioned medium from transfected 293T cells coexpressing full-length TNX and VEGF-B could promote DNA synthesis in bovine endothelial cells in which VEGFR-1 were expressed. VEGFR-1 phosphorylation triggered by VEGF-B186 were increased in cells plated with mTNX/FNIII13-25 or full-length mTNX, compared with cells plated with VEGF-B186 alone.

CONCLUSION

TNX interacts with VEGF-B and enhances the ability of VEGF-B to stimulate cell proliferation. This enhanced mitogenecity is caused by increased signals mediated by the VEGFR-1 receptor. This finding suggests a role for TNX in the regulation of the development of blood vessels such as vasculogenesis and angiogenesis.

Primary structure, genomic organization and expression of the major secretory protein of murine epididymis, ME1

The mouse cDNA and its genomic clones encoding the epididymal secretory glycoprotein ME1 were identified. The Me1 gene spans 15kb with four exons and three introns. The deduced amino-acid sequence of the ME1 cDNA revealed that it consists of 149 amino acid residues, which contain a signal peptide characteristic of secretory proteins, six cysteine residues and a proline-rich region conserved in the orthologous proteins. Northern blot analysis revealed that 1.3kb ME1 mRNA is highly expressed in the mouse epididymis. The polyclonal antibodies generated against human HE1 (ME1 orthologous protein) expressed in bacteria reacted with approximately 17 to 25kDa components in mouse epididymis crude extract. The reduction of the molecular mass of the recombinant ME1 protein with the digestion of glycopeptidase A indicated that it is modified by Asn-linked glycosylation.

Cholesterol sulfate, an activator of protein kinase C mediating squamous cell differentiation: a review

Activity of protein kinase C (PKC) depends on the interaction with polar head-groups of two membrane lipids, i.e., phosphatidylserine and diacylglycerol. We demonstrated that cholesterol metabolism is directly involved in activation of the eta isoform of protein kinase C (PKCeta), which is predominantly expressed in epithelial tissues in close association with epithelial differentiation. We found that PKCeta was activated by cholesterol sulfate (CS), a metabolite of cholesterol formed during squamous cell differentiation. In the presence of CS, phorbol ester only weakly enhanced the activity of PKCeta. CS also activated PKCeta, PKCdelta and PKCepsilon in a dose-dependent manner, when assayed using purified recombinant materials. However, when partially purified materials were used from overexpressing normal human keratinocytes, only PKCeta was activated by CS among the isoforms examined. All the existing lines of evidence, mainly supplied from our laboratory, suggest that CS is involved in a signal transduction of squamous cell differentiation and thereby modifying squamous cell carcinogenesis.

Nucleocytoplasmic shuttling of the aryl hydrocarbon receptor

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that acts in concert with the AhR nuclear translocator (ARNT), and alters gene expression in response to environmental contaminants such as 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD). We have previously shown that AhR contains both a nuclear localization signal (NLS), AhR(13-39), and a nuclear export signal (NES), AhR(55-75), in its NH(2)-terminal region. In this study, we obtained direct evidence for the nucleocytoplasmic shuttling of AhR and show the biological significance of the shuttling in terms of the transcriptional activation of its target gene, CYP1A1. When AhR(13-75) fused with glutathione S-transferase (GST)-green fluorescent protein (GFP) was microinjected into the nucleus of a polykaryotic of BHK21 cell, the GST-AhR(13-75)-GFP migrated from one nucleus to the other. This event, nucleocytoplasmic shuttling, was completely inhibited in the presence of leptomycin B (LMB). The interaction between chromosome region maintenance 1 (CRM1) and endogenous AhR was shown by immunoprecipitation with antibodies to AhR followed by immunoblot analysis with antibodies to CRM1. The inhibition of the nuclear export of AhR by LMB repressed the transcriptional activation of the CYP1A1 gene. The findings suggest that nuclear-cytoplasmic shuttling of AhR is essential for the inducible expression of the CYP1A1 protein.

Association of CYP1B1 genetic polymorphism with incidence to breast and lung cancer

Cytochrome P450 1B1 (CYP1B1) participates in the metabolic activation of a number of procarcinogens including benzo[a]pyrene and the hydroxylation of 17beta-estradiol at the C-4 position. In this study, we investigated the association between CYP1B1 genetic polymorphism and breast or lung cancer incidence. The Ala-Ser polymorphism at codon 119 in presumed substrate recognition site 1 was significantly associated with the incidence of breast or squamous cell carcinoma of the lung. On the other hand, Leu-Val polymorphism at codon 432 did not show any association to the cancers. An allele containing both Ala and Leu simultaneously, comprised 75% of alleles among 315 Japanese healthy controls, was significantly inversely associated with breast cancer incidence. When expressed in a recombinant system, this CYP1B1 cDNA showed the lowest 17beta-estradiol 4-hydroxylase activity among four different variant forms of CYP1B1. Thus, inter-individual differences in activation of procarcinogens or metabolism of oestrogen originating from genetic polymorphisms of the human CYP1B1 gene may contribute to the susceptibility of human cancers.

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal

Ku antigen is a complex of Ku70 and Ku80 subunits and plays an important role in not only DNA double-strand breaks (DSB) repair and V(D)J recombination, but also in growth regulation. Ku is generally believed to always form and function as heterodimers on the basis of in vitro observations. Here we demonstrate that the localization of Ku80 does not completely coincide with that of Ku70. Ku70 and Ku80 were colocalized in the nucleus in the interphase but not in the late telophase/early G1 phase of the cell cycle. Since the in vivo function of Ku might be partially regulated by the control of its transport, we attempted to investigate the molecular mechanisms underlying the nuclear translocation of Ku. The nuclear translocation of Ku80 started during the late telophase/early G1 phase after the nuclear envelope was formed and this was preceded by the nuclear translocation of Ku70. Furthermore, we found that the Ku80 protein was transported to the nucleus without heterodimerization with Ku70. To understand in detail the mechanism of transport of Ku80, we attempted to identify the nuclear localization signal (NLS) of Ku80 and defined to a region spanning nine amino acid residues (positions 561 - 569). The Ku80 NLS was demonstrated to be mediated to the nuclear rim by two components of PTAC58 and PTAC97. All these findings support the idea that Ku80 can translocate to the nucleus using its own NLS independent of the translocation of Ku70.

The nuclear localization signal of the human Ku70 is a variant bipartite type recognized by the two components of nuclear pore-targeting complex

Ku protein is a complex of two subunits, Ku70 and Ku80. Ku is suspected to participate in both DNA double-strand break repair and transcription. Since both of these processes take place in the cell nucleus, we have been investigating the subcellular localization and nuclear transport of Ku proteins. In the present study, we analyzed the subcellular localization and nuclear localization signal (NLS) of Ku70. Fusion proteins of Ku70 and green fluorescent protein (GFP) transiently expressed in cells were clearly localized in the nuclei of interphase cells. Ku70 staining was distributed throughout both the nucleus and the cytoplasm in late telophase to early G1 phase cells. The NLS of Ku70 was located at the region composed of 18 amino acid residues (positions 539 to 556). This region overlapped with the Ku80-independent DNA-binding domain reported previously. The Ku70 NLS consisted of two basic subregions and a nonbasic intervening region. All the subregions were necessary for complete NLS activity. The amino acids in the nonbasic intervening region of Ku70 might be important for full NLS activity not only to provide sufficient length between the two separated clusters of basic amino acids but also to have an adequate amino acid sequence. All of the basic amino acid residues in the basic subregions were conserved among mammalian and avian homologues, confirming their importance in the nuclear translocation of Ku70. The structure of the Ku70 NLS resembled the consensus of a bipartite-type NLS. The Ku70 NLS was mediated to target to the nuclear rim by two components of the nuclear pore-targeting complex, PTAC58 and PTAC97.

Cholesterol sulfate activates transcription of transglutaminase 1 gene in normal human keratinocytes

Cholesterol sulfate and transglutaminase 1 are essential for the process of keratinization. Cholesterol sulfate is formed during keratinization and activates the eta isoform of protein kinase C. Transglutaminase 1 is a key enzyme for formation of the cornified envelope in terminally differentiated keratinocytes. In this study, we demonstrated that cholesterol sulfate acts as a transcriptional activator of the transglutaminase 1 gene in normal human keratinocytes. Growth of normal human keratinocytes was inhibited by cholesterol sulfate, but not by its parental cholesterol. Treatment of normal human keratinocytes with cholesterol sulfate induced activity of transglutaminase 1 in a dose- and time-dependent manner. Activation of transcription of transglutaminase 1 by cholesterol sulfate was demonstrated by northern blotting analysis, whereas that by cholesterol was not. In order to identify a cholesterol sulfate responsive region in the transglutaminase 1 gene, plasmids were constructed containing a luciferase reporter gene ligated to deletion fragments of the 5' upstream region of the tranglutaminase 1 gene and were transfected into normal human keratinocytes. Transfected cells were treated with cholesterol sulfate, the phorbol ester 12-O-tetradecanoylphorbol-13-acetate and a high concentration of Ca2+. Our results indicate that the responsive element(s) for cholesterol sulfate and phorbol ester is located upstream of the human transglutaminase 1 gene at a position(s) between -819 and -549, whereas the responsive element for Ca2+ is located at a position between -79 and -49.