bluuebunny/crossref_metadata_2025 huggingface dataset:
Impacts of dislocation bending and impurity incorporation on the local cathodoluminescence spectra of GaN grown by ammonothermal method
Authors: Chichibu S. F. , Onuma T. , Hashimoto T. , Fujito K. , Wu F. , Speck J. S. , Nakamura S.
Published: December 2007

Spatially resolved cathodoluminescence (CL) spectra of GaN films grown on freestanding GaN seeds via fluid transport by the ammonothermal method were correlated with the microstructure and growth polarity. The spectral line shape of local CL was nearly position independent for a 4-μm-thick N-polar film exhibiting featureless morphology. The spectra exclusively exhibited a broad near-band-edge (NBE) free carrier recombination emission with Burstein-Moss shift. Conversely, CL spectra at 100K of a 5-μm-thick Ga-polar film having (101¯1) and (101¯2) facets with ridges originating from central pits exhibited a NBE peak at 3.444eV and emission bands at 3.27, 2.92, and 2.22eV, all of which showed rich intensity contrasts in the CL mapping images. The NBE peak intensity was remarkably enhanced at crests of the ridges, where the density of threading dislocations (TDs) having edge components was greatly reduced by the dislocation bending. The results encourage one to grow low TD density GaN wafers by slicing thick crystals grown by the ammonothermal method.
Emission studies on photonic crystals fabricated using dyed polystyrene colloids
Authors: Nair Rajesh V. , Vijaya R. , Kuroda Keiji , Sakoda Kazuaki
Published: December 2007

Three dimensionally ordered photonic crystals are fabricated with rhodamine B dyed polystyrene colloidal spheres using the inward growing self-assembling method in less than 3 h. This avoids the difficulties due to infiltration of active materials into passive photonic crystals. The superior optical quality of the photonic crystals fabricated using this method results in high reflectance values even at large angles of incidence. The study of emission characteristics on these functionalized photonic crystals shows a clear trend dependent on the angle of emission, wavelength, and the angle-resolved transmittance. The dip observed in the emission spectrum clearly matches the photonic stop band position at different angles of observation. The emission spectrum measured at different angles was found to follow a simple functional form related to the intrinsic emission of the dye and the stop band effect due to the photonic crystal environment.
Effect of surface hydrophilicity on the confined water film
Authors: Liu Shuhai , Ma Liran , Zhang Chenhui , Lu Xinchun
Published: December 2007

The effect of surface hydrophilicity on the water film confined within a nanogap between a smooth plate and a highly polished steel ball has been investigated. It was found that the confined water film formed the thicker lubricate film than the prediction of elastic-isoviscous lubrication theory. Experimental results indicated that the hydrophobic surface induced the thicker water film than the hydrophilic one. It is thought that the “structured” interfacial water layer is formed between the solid surfaces and the hydrophobic group induces the more ordered hydrogen-bonding network of clathrate cages which forms the thicker water film than hydrophilic one.
Strain responsive concave and convex microlens arrays
Authors: Chandra Dinesh , Yang Shu , Lin Pei-Chun
Published: December 2007

We report the fabrication of single-component, strain responsive microlens arrays with real-time tunability. The concave lens array is fabricated by patterning hard oxide layer on a bidirectionally prestretched soft elastomer, poly(dimethylsiloxane) (PDMS) followed by confined buckling upon release of the prestrain. The convex microlens array is replica molded from the concave lenses in PDMS. Due to difference in lens formation mechanisms, the two types of lenses show different tunable range of focal length in response to the applied strain: large focal length change is observed from the concave microlens array, whereas that from the convex microlens array is much smaller.
Processing of fullerene-single wall carbon nanotube complex for bulk heterojunction photovoltaic cells
Authors: Li Cheng , Mitra Somenath
Published: December 2007

A fullerene-single wall carbon nanotube (C60-SWCNT) complex is used as a component of the photoactive layer in bulk heterojunction photovoltaic cells. This complex synthesized by microwave-assisted reaction takes advantage of the electron accepting feature of C60 and the high electron transport capability of SWCNTs. In this paper, quantum efficiency enhancement by increasing light absorption and by bringing about appropriate morphological rearrangements via solvent vapor treatment and thermal annealing is presented. The optimum combination of these steps led to an increase in efficiency by as much as 87.5%.
Nonlinear air-coupled emission: The signature to reveal and image microdamage in solid materials
Authors: Solodov Igor , Busse Gerd
Published: December 2007

It is shown that low-frequency elastic vibrations of near-surface planar defects cause high-frequency ultrasonic radiation in surrounding air. The frequency conversion mechanism is concerned with contact nonlinearity of the defect vibrations and provides efficient generation of air-coupled higher-order ultraharmonics, ultrasubharmonics, and combination frequencies. The nonlinear air-coupled ultrasonic emission is applied for location and high-resolution imaging of damage-induced defects in a variety of solid materials.
Challenges for the determination of piezoelectric constants with piezoresponse force microscopy
Authors: Jungk Tobias , Hoffmann Ákos , Soergel Elisabeth
Published: December 2007

At first sight, piezoresponse force microscopy (PFM) seems an ideal technique for the determination of piezoelectric coefficients, thus making use of its ultrahigh vertical resolution (<0.1pm∕V). In general, however, only qualitative PFM imaging is performed and in the few publications containing quantitative data, the obtained values vary considerably with respect to macroscopic measurements. In this contribution, we present a reliable calibration procedure for PFM followed by a careful analysis of the encounted difficulties using PFM for determining piezoelectric coefficients. We point out different approaches for their solution and expose why those difficulties cannot be circumvented without an extensive effort.
Prion detection by an amyloid seeding assay
Authors: Colby David W. , Zhang Qiang , Wang Shuyi , Groth Darlene , Legname Giuseppe , Riesner Detlev , Prusiner Stanley B.
Published: December 2007

Polymerization of recombinant prion protein (recPrP), which was produced in bacteria, into amyloid fibers was accompanied by the acquisition of prion infectivity. We report here that partially purified preparations of prions seed the polymerization of recPrP into amyloid as detected by a fluorescence shift in the dye Thioflavin T. Our amyloid seeding assay (ASA) detected PrP
Sc
, the sole component of the prion, in brain samples from humans with sporadic Creutzfeldt–Jakob disease, as well as in rodents with experimental prion disease. The ASA detected a variety of prion strains passaged in both mice and hamsters. The sensitivity of the ASA varied with strain type; for hamster Sc237 prions, the limit of detection was ≈1 fg. Some prion strains consist largely of protease-sensitive PrP
Sc
(sPrP
Sc
), and these strains were readily detected by ASA. Our studies show that the ASA provides an alternative methodology for detecting both sPrP
Sc
and protease-resistant PrP
Sc
that does not rely on protease digestion or immunodetection.
Early maternal feeding following caesarean delivery: a prospective randomised study
Authors: BAR GUY , SHEINER EYAL , LEZEROVIZT ADI , LAZER TAL , HALLAK MORDECHAI
Published: December 2007

Objective. To evaluate the effect of early maternal feeding on maternal satisfaction and gastrointestinal complications on patients following simple and complicated caesarean delivery (CD). Methods. A prospective, randomised study was designed including 179 women undergoing first or repeated CD. Women who were assigned to the early feeding group received clear fluids and solid food within 8 h of surgery, in accordance with their request. The traditionally fed women received clear fluids 8–12 h after the surgery subsequent to physician examination confirming bowel sounds. Results. Some 82 women were assigned to the traditionally fed group and 97 women were assigned to the early fed group. Maternal satisfaction was significantly higher among the early fed women. No significant differences were noted between the groups regarding post‐operative complications. Conclusions. Early maternal feeding following CD is associated with higher maternal satisfaction. However, it is not associated with higher rates of post‐operative complications.
Comparative genomics beyond sequence-based alignments: RNA structures in the ENCODE regions
Authors: Torarinsson Elfar , Yao Zizhen , Wiklund Eric D. , Bramsen Jesper B. , Hansen Claus , Kjems Jørgen , Tommerup Niels , Ruzzo Walter L. , Gorodkin Jan
Published: December 2007

Recent computational scans for non-coding RNAs (ncRNAs) in multiple organisms have relied on existing multiple sequence alignments. However, as sequence similarity drops, a key signal of RNA structure—frequent compensating base changes—is increasingly likely to cause sequence-based alignment methods to misalign, or even refuse to align, homologous ncRNAs, consequently obscuring that structural signal. We have used CMfinder, a structure-oriented local alignment tool, to search the ENCODE regions of vertebrate multiple alignments. In agreement with other studies, we find a large number of potential RNA structures in the ENCODE regions. We report 6587 candidate regions with an estimated false-positive rate of 50%. More intriguingly, many of these candidates may be better represented by alignments taking the RNA secondary structure into account than those based on primary sequence alone, often quite dramatically. For example, approximately one-quarter of our predicted motifs show revisions in >50% of their aligned positions. Furthermore, our results are strongly complementary to those discovered by sequence-alignment-based approaches—84% of our candidates are not covered by Washietl et al., increasing the number of ncRNA candidates in the ENCODE region by 32%. In a group of 11 ncRNA candidates that were tested by RT-PCR, 10 were confirmed to be present as RNA transcripts in human tissue, and most show evidence of significant differential expression across tissues. Our results broadly suggest caution in any analysis relying on multiple sequence alignments in less well-conserved regions, clearly support growing appreciation for the biological significance of ncRNAs, and strongly support the argument for considering RNA structure directly in any searches for these elements.
Genome-wide analysis reveals regulatory role of G4 DNA in gene transcription
Authors: Du Zhuo , Zhao Yiqiang , Li Ning
Published: December 2007

G-quadruplex or G4 DNA, a four-stranded DNA structure formed in G-rich sequences, has been hypothesized to be a structural motif involved in gene regulation. In this study, we examined the regulatory role of potential G4 DNA motifs (PG4Ms) located in the putative transcriptional regulatory region (TRR, –500 to +500) of genes across the human genome. We found that PG4Ms in the 500-bp region downstream of the annotated transcription start site (TSS; PG4MD500) are associated with gene expression. Generally, PG4MD500-positive genes are expressed at higher levels than PG4MD500-negative genes, and an increased number of PG4MD500 provides a cumulative effect. This observation was validated by controlling for attributes, including gene family, function, and promoter similarity. We also observed an asymmetric pattern of PG4MD500 distribution between strands, whereby the frequency of PG4MD500 in the coding strand is generally higher than that in the template strand. Further analysis showed that the presence of PG4MD500 and its strand asymmetry are associated with significant enrichment of RNAP II at the putative TRR. On the basis of these results, we propose a model of G4 DNA-mediated stimulation of transcription with the hypothesis that PG4MD500 contributes to gene transcription by maintaining the DNA in an open conformation, while the asymmetric distribution of PG4MD500 considerably reduces the probability of blocking the progression of the RNA polymerase complex on the template strand. Our findings provide a comprehensive view of the regulatory function of G4 DNA in gene transcription.
Generic eukaryotic core promoter prediction using structural features of DNA
Authors: Abeel Thomas , Saeys Yvan , Bonnet Eric , Rouzé Pierre , Van de Peer Yves
Published: December 2007

Despite many recent efforts, in silico identification of promoter regions is still in its infancy. However, the accurate identification and delineation of promoter regions is important for several reasons, such as improving genome annotation and devising experiments to study and understand transcriptional regulation. Current methods to identify the core region of promoters require large amounts of high-quality training data and often behave like black box models that output predictions that are difficult to interpret. Here, we present a novel approach for predicting promoters in whole-genome sequences by using large-scale structural properties of DNA. Our technique requires no training, is applicable to many eukaryotic genomes, and performs extremely well in comparison with the best available promoter prediction programs. Moreover, it is fast, simple in design, and has no size constraints, and the results are easily interpretable. We compared our approach with 14 current state-of-the-art implementations using human gene and transcription start site data and analyzed the ENCODE region in more detail. We also validated our method on 12 additional eukaryotic genomes, including vertebrates, invertebrates, plants, fungi, and protists.
Estimating the length of transmembrane helices using Z‐coordinate predictions
Authors: Papaloukas Costas , Granseth Erik , Viklund Håkan , Elofsson Arne
Published: December 2007

Zpred2 is an improved version of ZPRED, a predictor for the Z‐coordinates of α‐helical membrane proteins, that is, the distance of the residues from the center of the membrane. Using principal component analysis and a set of neural networks, Zpred2 analyzes data extracted from the amino acid sequence, the predicted topology, and evolutionary profiles. Zpred2 achieves an average accuracy error of 2.18 Å (2.17 Å when an independent test set is used), an improvement by 15% compared to the previous version. We show that this accuracy is sufficient to enable the predictions of helix lengths with a correlation coefficient of 0.41. As a comparison, two state‐of‐the‐art HMM‐based topology prediction methods manage to predict the helix lengths with a correlation coefficient of less than 0.1. In addition, we applied Zpred2 to two other problems, the re‐entrant region identification and model validation. Re‐entrants were able to be detected with a certain consistency, but not better than with previous approaches, while incorrect models as well as mispredicted helices of transmembrane proteins could be distinguished based on the Z‐coordinate predictions.
Contributions of a disulfide bond to the structure, stability, and dimerization of human IgG1 antibody CH3 domain
Authors: McAuley Arnold , Jacob Jaby , Kolvenbach Carl G. , Westland Kimberly , Lee Hyo Jin , Brych Stephen R. , Rehder Douglas , Kleemann Gerd R. , Brems David N. , Matsumura Masazumi
Published: December 2007

Recombinant human monoclonal antibodies have become important protein‐based therapeutics for the treatment of various diseases. The antibody structure is complex, consisting of β‐sheet rich domains stabilized by multiple disulfide bridges. The dimerization of the CH3 domain in the constant region of the heavy chain plays a pivotal role in the assembly of an antibody. This domain contains a single buried, highly conserved disulfide bond. This disulfide bond was not required for dimerization, since a recombinant human CH3 domain, even in the reduced state, existed as a dimer. Spectroscopic analyses showed that the secondary and tertiary structures of reduced and oxidized CH3 dimer were similar, but differences were observed. The reduced CH3 dimer was less stable than the oxidized form to denaturation by guanidinium chloride (GdmCl), pH, or heat. Equilibrium sedimentation revealed that the reduced dimer dissociated at lower GdmCl concentration than the oxidized form. This implies that the disulfide bond shifts the monomer–dimer equilibrium. Interestingly, the dimer–monomer dissociation transition occurred at lower GdmCl concentration than the unfolding transition. Thus, disulfide bond formation in the human CH3 domain is important for stability and dimerization. Here we show the importance of the role played by the disulfide bond and how it affects the stability and monomer–dimer equilibrium of the human CH3 domain. Hence, these results may have implications for the stability of the intact antibody.
Folding thermodynamics and kinetics of the leucine‐rich repeat domain of the virulence factor Internalin B
Authors: Courtemanche Naomi , Barrick Doug
Published: December 2007

Although the folding of α‐helical repeat proteins has been well characterized, much less is known about the folding of repeat proteins containing β‐sheets. Here we investigate the folding thermodynamics and kinetics of the leucine‐rich repeat (LRR) domain of Internalin B (InlB), an extracellular virulence factor from the bacterium Lysteria monocytogenes. This domain contains seven tandem leucine‐rich repeats, of which each contribute a single β‐strand that forms a continuous β‐sheet with neighboring repeats, and an N‐terminal α‐helical capping motif. Despite its modular structure, InlB folds in an equilibrium two‐state manner, as reflected by the identical thermodynamic parameters obtained by monitoring its sigmoidal urea‐induced unfolding transition by different spectroscopic probes. Although equilibrium two‐state folding is common in α‐helical repeat proteins, to date, InlB is the only β‐sheet‐containing repeat protein for which this behavior is observed. Surprisingly, unlike other repeat proteins exhibiting equilibrium two‐state folding, InlB also folds by a simple two‐state kinetic mechanism lacking intermediates, aside from the effects of prolyl isomerization on the denatured state. However, like other repeat proteins, InlB also folds significantly more slowly than expected from contact order. When plotted against urea, the rate constants for the fast refolding and single unfolding phases constitute a linear chevron that, when fitted with a kinetic two‐state model, yields thermodynamic parameters matching those observed for equilibrium folding. Based on these kinetic parameters, the transition state is estimated to comprise 40% of the total surface area buried upon folding, indicating that a large fraction of the native contacts are formed in the rate‐limiting step to folding.
DNA inhibits catalysis by the carboxyltransferase subunit of acetyl‐CoA carboxylase: Implications for active site communication
Authors: Benson Brian K. , Meades Glen , Grove Anne , Waldrop Grover L.
Published: December 2007

Acetyl‐CoA carboxylase (ACC) catalyzes the first committed step in the synthesis of long‐chain fatty acids. The crystal structure of the Escherichia coli carboxyltransferase component of ACC revealed an α2β2 subunit composition with two active sites and, most importantly, a unique zinc domain in each αβ pair that is absent in the eukaryotic enzyme. We show here that carboxyltransferase binds DNA. Half‐maximal saturation of different single‐stranded or double‐stranded DNA constructs is seen at 0.5–1.0 μM, and binding is cooperative and nonspecific. The substrates (malonyl‐CoA and biocytin) inhibit DNA:carboxyltransferase complex formation. More significantly, single‐stranded DNA, double‐stranded DNA, and heparin inhibit the reaction catalyzed by carboxyltransferase, with single‐stranded DNA and heparin acting as competitive inhibitors. However, double‐inhibition experiments revealed that both DNA and heparin can bind the enzyme in the presence of a bisubstrate analog (BiSA), and the binding of BiSA has a very weak synergistic effect on the binding of the second inhibitor (DNA or heparin) and vice versa. In contrast, DNA and heparin can also bind to the enzyme simultaneously, but the binding of either molecule has a strong synergistic effect on binding of the other. An important mechanistic implication of these observations is that the dual active sites of ACC are functionally connected.
Enhanced performance in prediction of protein active sites with THEMATICS and support vector machines
Authors: Tong Wenxu , Williams Ronald J. , Wei Ying , Murga Leonel F. , Ko Jaeju , Ondrechen Mary Jo
Published: December 2007

Theoretical microscopic titration curves (THEMATICS) is a computational method for the identification of active sites in proteins through deviations in computed titration behavior of ionizable residues. While the sensitivity to catalytic sites is high, the previously reported sensitivity to catalytic residues was not as high, about 50%. Here THEMATICS is combined with support vector machines (SVM) to improve sensitivity for catalytic residue prediction from protein 3D structure alone. For a test set of 64 proteins taken from the Catalytic Site Atlas (CSA), the average recall rate for annotated catalytic residues is 61%; good precision is maintained selecting only 4% of all residues. The average false positive rate, using the CSA annotations is only 3.2%, far lower than other 3D‐structure‐based methods. THEMATICS–SVM returns higher precision, lower false positive rate, and better overall performance, compared with other 3D‐structure‐based methods. Comparison is also made with the latest machine learning methods that are based on both sequence alignments and 3D structures. For annotated sets of well‐characterized enzymes, THEMATICS–SVM performance compares very favorably with methods that utilize sequence homology. However, since THEMATICS depends only on the 3D structure of the query protein, no decline in performance is expected when applied to novel folds, proteins with few sequence homologues, or even orphan sequences. An extension of the method to predict non‐ionizable catalytic residues is also presented. THEMATICS–SVM predicts a local network of ionizable residues with strong interactions between protonation events; this appears to be a special feature of enzyme active sites.
Successful Palliative Treatment of Gastric Cancer with Splenic Metastasis and Tumor Thrombosis of the Portal Vein by Endoscopic Injection of OK‐432 Directly into the Primary Tumor
Authors: YAMAMOTO Osami , SATO Michio , IWAO Akiko , SHIMIZU Ken
Published: December 2007

Abstract: We describe a case with main portal vein tumor thrombosis and splenic metastases from a gastric cancer. This is the first clinical report of these two metastases occurring concomitantly. The patient had no liver metastasis prior to therapy. We judged the tumor in this case to be unresectable and injected OK‐432 directly into the primary gastric cancer. Injection of OK‐432 resulted in remarkable reductions, in the sizes of the metastatic lesions in the spleen and some reduction in the size of the primary tumor. Moreover, the patient survived for 1 year and 7 months, commuting 544 km monthly by train for 1 year and 4 months to undergo treatment. The course of this patient suggests that the main effect was local immune activation, rather than an increase in systemic nonspecific immune functions. In addition, this therapy was very useful for maintaining the quality of life of this patient.
Acute Graft‐Versus‐Host Disease of the Large Intestine after Bone Marrow Transplantation
Authors: HARUTA Jun‐ichi , KUSUGAMI Kazuo , YAMAGUCHI Takeo , ITO Masafumi , OKA Yuji , KUSAKABE Atsuhiko , TAKEDA Nobuhiko , NOBATA Kazuo , SAITO Hidehiko
Published: December 2007

Abstract: A 13‐year old male with acute lymphocytic leukemia was admitted to our hospital for bone marrow transplantation (BMT). Lower abdominal pain and bloody diarrhea developed during the fourth post‐BMT week. Colonoscopy revealed edematous mucosa, erosions and multiple irregular ulcers in the rectum and sigmoid colon. Histologically, multiple apoptotic lesions were recognizable in the crypt basement membrane. Most infiltrating lymphoid cells were mature memory T lymphocytes bearing LFA‐la‐, CD43 and CD45RO antigens. HLA‐DR and ICAM‐1 immunostaining was seen on the vascular endothelium and the epithelium stained positively for HLA‐DR antigens.
A Case with Multiple Colonic Ulcers Simulating Churg‐Strauss Syndrome
Authors: IKEDA Hideo , KOHAKURA Makoto , MINETOMA Tomoaki , IKEDA Nobuhiro , KAWAGUCHI Shinzo , IMAMURA Yutaka , ITO Yuji , SAKAI Terufumi , IDE Koichi , TOMOYOSE Michiko , TSURUTA Osamu , TOYONAGA Atsushi , TANIKAWA Kyuichi
Published: December 2007

Abstract: Churg‐Strauss syndrome (CSS), a relatively rare disorder which is associated with serious complications, has a highly variable course and several possible manifestations. We present the case of a 35‐year‐old woman with a history of bronchial asthma, admitted for evaluation of lower abdominal pain and melena, whose clinical course had certain features in common with CSS. On admission, the white blood cell count was 45,300/mm3 with 65% eosinophils, and the serum immunoglobulin E (5,300 u/ml) level was remarkably elevated. At colonoscopy, there were shallow ulcers, irregular in shape, throughout the large intestine. Abdominal pain and melena were relieved by oral administration of prednisolone. Most previously reported cases have not been recognized as having colonic involvement until surgery or autopsy. In only a few reports of CSS and related disorders were colonoscopic examination findings described.
Use of the Ultrasonic Microprobe to Evaluate Gastric Varices –Comparison with Endoscopic Color Doppler Ultrasonography–
Authors: SATO Takahiro , YAMAZAKI Katsu , TOYOTA Jouji , KARINO Yoshiyasu , OMURA Takumi , SUGA Toshihiro
Published: December 2007

Abstract: This study was designed to evaluate the usefulness of the ultrasonic microprobe (UMP), as compared with endoscopic color Doppler ultrasonography (ECDUS), in detecting gastric varices in 18 patients. The gastric varices detected were categorized as follows: 14 F2 type varices, four F3 type. Among the 18 cases, four had cardiac varices, nine cardiofornical varices, and five fundic varices. UMP was easily performed visually by using an endoscope with a UM‐3R (20MHz) probe, inserted via the biopsy channel, and a display unit (Olympus EU‐M20). ECDUS was performed using a PENTAX FG‐32UA and a FG‐36UX, 7.5MHz, convex type. The display monitor was a HITACHI EUB 565.

We were able to clearly delineate the vessel images of gastric varices in all 18 patients using UMP. Although the overall features of the peri‐gastric collateral veins could not be discerned with UMP, the color flow images of gastric varices and peri‐gastric collateral veins were clearly visualized in all 18 patients using ECDUS. It was thus possible to determine blood flow direction using ECDUS.

We found the use of UMP to be advantageous in terms of the ease of operation and the excellent view provided of gastric varices. The fact that, due to limited penetration, UMP inadequately delineates the peri‐gastric collateral veins was determined to be a major drawback. Therefore, we recommend ECDUS for evaluating overall hemodynamics. It was, however, technically difficult to scan the fundal region because of the characteristics of the ECDUS instrument.

Thus, we conclude that detailed evaluation of gastric varix hemodynamics is most successfully accomplished by using UMP in conjunction with ECDUS.
A Trial of 13C‐urea Breath Test Combined with Endoscopic Phenol Red Test for Detection of Helicobacter pylori Infection
Authors: SUTO Hiroyuki , AZUMA Takeshi , ITO Shigeji , ITO Yoshiyuki , MIYAJI Hideki , YAMAZAKI Yukinao , HIRANO Fukiko , KURIYAMA Masaru , KOHLP Yoshihiro
Published: December 2007

Abstract: Several tests for the diagnosis of Helicobacter pylori [H. pylori) infection have been employed in clinical studies. To minimize inaccuracies of these tests, we developed a new method which combines the 13C‐urea breath test (UBT) with phenol red dye spraying endoscopy. We have designated this innovation the endoscopic 13C‐urea breath test (EUBT). EUBT was conducted on 103 patients with gastroduodenal diseases. After the collection of a baseline breath sample, gastroduodenal endoscopy was performed. Twenty milliliters of 0.05% phenol red solution containing 100 milligrams of 13C‐urea was sprayed onto the entire gastric mucosa. A breath sample was collected 15 minutes after spraying. We measured 13CO2 in the breath samples by ratio mass spectrometry. Two biopsy specimens each from the antrum and the middle corpus were obtained for culture and histological examination. The mean EUBT values (±standard deviation) in H. pylori ‐positive and negative patients were 38.56±30.34%< and 0.19± 0.18%), respectively. The cut‐off value for EUBT was 0.73%. The sensitivity and specificity of EUBT were 100% and 95.5%, as compared with culture, and 100% and 95.5%, as compared with histological evaluation. The EUBT value of the patients with the diffuse staining type (50.28±31.26%) was significantly higher than that of patients with the regional staining type (26.76±23.17%). EUBT is an accurate method of detecting H. pylori infection and a good indicator of the distribution of the infection within the stomach.
High‐frequency Intraductal Ultrasound Images of Biliary Tract Lesions: Experimental Studies
Authors: UENO Norio , NISHIZONO Takashi
Published: December 2007

Abstract: To investigate the differences in images obtained with a 3.75 MHz, 7.5 MHz or 20 MHz transducer, 27 stones, five debris samples, and three cholesterol polyps were examined in a water tank. All stones showed definite acoustic shadowing on images produced with the 20 MHz transducer, although the acoustic shadowing was weak or absent on images produced by 3.75 MHz or 7.5 MHz transducers. Regarding the relation between stone size and the acoustic shadowing, this shadowing was visualized for stones as small as 1.5 mm when the 20 MHz transducer was used. The hyperechoic appearance changed to a sharp crescent shape with the high frequency transducer. Images of cholesterol polyps and debris produced by the 20 MHz transducer showed no fundamental differences when compared with conventional ultrasonographic images obtained with a 3.75 MHz transducer, and there was no accompanying acoustic shadowing. In conclusion, ultrasonic images obtained with high frequency transducers which are used in intraductal ultrasound are different from those produced with conventional ultrasound probes. These phenomena may be useful for differential diagnosis of biliary tract diseases.
Endoscopic Findings of Acute Intestinal Graft‐versus‐host Disease after Bone Marrow Transplantation
Authors: EGAWA Naoto , KATO Hiroaki , SAKAKI Nobuhiro , TAJIMA Tsuyoshi , SAKAMAKI Hisashi , AKIYAMA Hideki , TANIKAWA Syu , KAKU Hidefumi , HIRUMA Kiyoshi , KOIKE Morio
Published: December 2007

Abstract: To clarify the endoscopic findings of intestinal graft‐versus‐host disease (GVHD), we reviewed the endoscopic findings of 19 patients who underwent colonoscopy because of abdominal pain, watery diarrhea or bloody stool among 196 bone marrow transplant (BMT) recipients between 1986 and 1997. BMT had been performed for treatment of various hematopoietic disorders. Eleven patients were diagnosed as having intestinal GVHD, based on the pathological findings of biopsy specimens. Although the grade of inflammation differed among cases, the terminal ileum was most vulnerable to GVHD, based on our observations. Compared to the ileum, findings in the colon tended to be mild. Therefore, evaluation of intestinal GVHD requires observation of the terminal ileum when the colorectal findings are mild. The findings consisted of shallow ulcerations, erythema and easy bleeding. However, there were very few specific endoscopic findings of intestinal GVHD. Since intestinal GVHD and cytomegalovirus (CMV) enterocolitis share several clinical characteristics, including preferential involvement of the ileum, biopsy is indispensable for the final diagnosis.
An Evaluation of the Efficacy of Preoperative Therapy for Thoracic Esophageal Carcinoma Using Endoscopic Ultrasonography
Authors: OTA Masaho , MURATA Yoko , IDE Hiroko , HAYASHI Kazuhiko , EGUCHI Reiki , SUZUKI Shigeru , TAKASAKI Ken
Published: December 2007

Abstract: We performed endoscopic ultrasonography (EUS) to assess the therapeutic efficacy of thoracic esophageal carcinoma treatment and compared this assessment with that of histology. The subjects were 43 patients who underwent surgical resection following preoperative chemotherapy for advanced thoracic esophageal carcinoma. The region of maximal thickness and the cross‐sectional area of the tumor were measured, and the percent reduction was taken to be the degree of reduction. Total assessment of metastatic lymph nodes was made on the basis of the degree of reduction in the major axis and cross‐sectional area, and the three elements of morphology, border echo and inner echo. The histological findings were classified into Grades 0 through 3 according to criteria for the management of esophageal carcinoma and compared with the EUS findings. The reduction in tumor thickness was 30% or less in 16 patients, 14 (87.5%) of whom had Grades of 0 to 1. The degree of reduction was greater than 50% in 17 patients, 15 (88.2%) of whom had Grades 2 to 3. The degree of reduction was 60% or greater in eight patients, six (75%) of whom had a Grade of 3. Reduction in the cross‐sectional area was less than 50% in 19 patients, 16 (84.2%) of whom had Grades of 0 to 1. Of the 19, all who showed a reduction of 30% or less had Grades of 0 to 1. The reduction in cross‐sectional area was greater than 50% in 24 patients, 20 (83.3%) of whom had Grades of 2 to 3. A significant difference was noted in the correlation between reduction in thickness and histological assessment between Grades 0 to 1 and Grade 2 (p<0.01) and between of Grades 2 and 3 (p<0.02). The correlation between reduction in cross‐sectional area and histological assessment was similar to that for reduction in thickness. None of the methods produced satisfactory results in relation to assessment of metastatic lymph nodes. Assessment of accuracy by down‐staging did not prove useful.
Postoperative Complications Associated with Laparoscopy‐assisted Colectomy
Authors: KONISHI Fumio , NAGAI Hideo , OZAWA Akihito , OHKI Jun , KANAZAWA Kyotaro
Published: December 2007

Abstract: The intraoperative and postoperative complications of laparoscopic colectomy were analyzed in a consecutive series of 69 cases in our experience. The final histological diagnosis of these patients was adenoma of the colon in eight, carcinoma of the colon and rectum in 59, leiomyoma of the colon in one and Crohn's disease in one. The TIMM staging of the carcinomas in our series was Tis in four, T1 in 20, T2 in 10 and T3 in 25 cases. Conversion to open surgery was necessary in four of the 69 cases. The reasons for conversion were bleeding in two, adhesion in one and malignant invasion to the bladder in one. Major postoperative complications occurred in the four cases in whom a reoperation was carried out. These included perforation of the colon, pancreatic fistula, ileus and bleeding. Among the 11 minor postoperative complications, wound infection was the most frequent and occurred in six cases. There were no operative or postoperative deaths. The postoperative observation period ranged from one month to 41/2 years. There was only one case with a possible local recurrence who had a CEA level of 34 ng/ml. In this patient, no findings of port site recurrence were detected. We thus consider laparoscopic‐assisted colectomy, when done by technically well experienced surgeons, to be an effective and curative procedure for the treatment of colorectal carcinoma. However, in view of our complication rate, both sufficient training and experience with the techniques required to perform a laparoscopic colectomy are important for the future development of this procedure.
Buried Bumper Syndrome as a Rare Complication of Percutaneous Endoscopic Gastrostomy
Authors: NISHIGUCHI Yukio , YOSHIKAWA Kazuhiko , MICHIGAMI Shinya , TANAKA Hiroaki , OSAKA Hirohisa , SOWA Michio
Published: December 2007

Abstract: Percutaneous Endoscopic Gastrostomy (PEG), which can be performed under local anesthesia and does not require laparotomy, has become an accepted means of providing long‐term nutritional support for patients who cannot swallow. PEG can be successfully performed in 10–20 minutes with minimal invasion. Although the incidences are low, some complications with PEG have been reported. We describe herein a patient who developed an early complication of PEG in which the internal bumper became buried in the gastric wall. The buried bumper was immediately removed under local anesthesia, and a new PEG tube was successfully placed. There have also been reports of tube migration into the appears to result from excessive traction on the tube with subsequent ischemic necrosis of the gastric mucosa and pressure necrosis. Careful management of the tube is needed prevent this complication.
Endoscopic Dilatation Therapy Using a Small Caliber Balloon for Esophageal Achalasia
Authors: ITOH Hidekazu , SAIKA Akihiro , OKA Hisato , SHIOTANI Akiko , HARA Takeshi , NISHIOKA Shingo , HIGASHP Katsuhiko , TAKATSUJI Mikio
Published: December 2007

Balloon dilation therapy under direct endoscopic vision was performed in three patients with esophageal achalasia. The Rigiflex through‐the‐scope balloon dilator, with a maximum diameter of 10–25 mm, was used for dilatation, with a 10‐min inflation period. In all patients, dysphagia and regurgitation improved, body weight increased, and esophagography revealed a decrease in esophageal diameter. Our approach differs from standard methods used in Europe and America, in that the balloon has a smaller diameter and the duration of inflation is longer. Although our balloon dilator was small caliber, satisfactory results were obtained because of the longer duration of inflation. We conclude that balloon dilatation is the first choice for treatment of esophageal achalasia, and that to increase the safety of this technique, it is necessary to begin such treatment with a small caliber balloon under direct endoscopic vision.
Choledocholithiasis: Evaluation with MR Cholangiography
Authors: TSITOURIDIS John , KOUKLAKIS George , PAPASTERGIOU Christos , IASONIDOU Christina , XIARCHOS Panagiotis
Published: December 2007

This retrospective study compared imaging results with surgery findings in 26 choledocholithiasis patients who were examined with two‐dimensional fast spin‐echo (2D‐FSE) MR cholangiography and half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) MR cholangiography. Patients were examined using a 1, 5 T Philips Gyroscan ACS\11 MR scanner and a 1 T Siemens Harmony MR scanner. A total of 21 of the 26 patients with diagnosed choledocholithiasis on imaging were proven to have common bile ducts stones. Two patients had another small stone which was impacted into the Vater and which was not detected with MR cholangiography. One patient with mild dilated common bile duct and pancreatic duct also had a small impacted stone which was not detected by MR cholangiography. One patient had an irregular stone in the hepatic duct, extending partially into the left hepatic duct which was misintepretated as carcinoma. The last patient had a dilated common bile duct due to a small impacted stone which was not detected and biliary sludge which was misintepretated as a stone. The overall sensitivity of MR cholangiography in the detection of common bile duct stones was 80.8%. In conclusion MR cholangiography can rapidly evaluate the common bile duct for stones. The only problem we encountered was in the evaluation of small impacted stones at the Vater. (Dig Endosc 1999; 11: 220–224)
Gastroduodenal Vascular Ectasia in Patients with Liver Cirrhosis
Authors: YAMADA Masahiko , ICHIKAWA Masafumi , TAKAHARA Osamu , TSUCHIDA Takeshi , ISHIHARA Akira , YAMADA Masahiro , NISHIMURA Daisaku , HOSHINO Hiroshi , KATADA Naoyuki , KATO Katsumoto
Published: December 2007

The purpose of this study was to determine the incidence of hemorrhage due to vascular ectasia of the upper gastrointestinal tract in patients with liver cirrhosis and to assess the prevalence in cirrhotic patients without clinically overt gastrointestinal bleeding. Out of 96 cirrhotic patients with upper gastrointestinal bleeding, vascular ectasia was diagnosed in 6 patients (6.3%) as the cause of bleeding. These 6 patients had numerous spotty or confluent erythemas consisting of ectatic and tortuous capillaries throughout the antrutn and 4 patients required blood transfusion before diagnostic en‐doscopy. Several sessions of endoscopic electrocoagulation resulted in eradication of almost all the abnormal vascular lesions and marked improvement of their anemia without further transfusion. The procedure was well tolerated and no resultant complications were encountered. Among 206 cirrhotic patients without clinically overt gastrointestinal bleeding 25 patients (12.1%) were diagnosed with vascular ectasia. The hemoglobin level was significantly lower in patients with vascular ectasia than those without vascular ectasia but the other features did not differ between the two groups. Vascular ectasia is an important cause of upper gastrointestinal bleeding and anemia in patients with liver cirrhosis. Endoscopic electrocoagulation may be a safe and effective treatment for controlling blood loss from gastroduodenal vascular ectasia in this subset of patients. (Dig Endosc 1999; 11: 241–245)
An Ulcer in the Gastric Tube Used for Esophageal Replacement after Esophagectomy — Report of a Case
Authors: HONMYO Ubehiko , SHIMADA Shinya , YAMAMOTO Shin‐ichi , KURAMOTO Masafumi , INADA Masayuki , OKABE Akihiro , TASHIMA Satoshi , MISUMI Atsunobu
Published: December 2007

Abstract: We report a patient with an asymptomatic recurrent peptic ulcer occurring in the gastric tube after reconstruction for esophagectomy with a long follow‐up. The patient is an 82‐year‐old male, who had undergone an esophagectomy for cancer, and a gastric tube was used for esophageal replacement at the age of 77 years. A follow‐up study using endoscopic examination revealed an active peptic ulcer in the gastric tube one year after the operation, ulcer scar formation 9 weeks after H2 receptor antagonist medication, and recurrence of the ulcer about 3 years after quitting the medication. The recurrent active ulcer has disappeared after re‐administration of H2 receptor antagonist. Helicobacter pylori has not been detected, although eradication has not been per formed. It is suggested that high acidity might play a part in the pathogenesis of ulcer formation despite the vagotomy. Since a peptic ulcer in the gastric tube can potentially cause serious complications including perforation and hemorrhage, we have to bear in mind not only recurrence of the cancer but also gastric tube ulceration in the follow‐up survey after esophagectomy, to facilitate early detection of ulcer and effective treat ment. (Dig Endosc 1999:11: 62–65)
Hypothalamic input is required for development of normal numbers of thyrotrophs and gonadotrophs, but not other anterior pituitary cells in late gestation sheep
Authors: Szarek Eva , Farrand Kirsten , McMillen I. Caroline , Young I. Ross , Houghton Daniel , Schwartz Jeffrey
Published: December 2007

To evaluate the hypothalamic contribution to the development of anterior pituitary (AP) cells we surgically disconnected the hypothalamus from the pituitary (hypothalamo‐pituitary disconnection, HPD) in fetal sheep and collected pituitaries 31 days later. Pituitaries (n= 6 per group) were obtained from fetal sheep (term = 147 ± 3 days) at 110 days (unoperated group) of gestation and at 141 days from animals that had undergone HPD or sham surgery at 110 days. Cells were identified by labelling pituitary sections with antisera against the six AP hormones. Additionally, we investigated the colocalization of glycoprotein hormones. The proportions of somatotrophs and corticotrophs were unchanged by age or HPD. Lactotrophs increased 80% over time, but the proportion was unaffected by HPD. Thyrotrophs, which were unaffected by age, increased 70% following HPD. Gonadotrophs increased with gestational age (LH+ cells 55%; FSH+ cells 19‐fold), but this was severely attenuated by HPD. We investigated the possible existence of a reciprocal effect of HPD on multipotential glycoprotein‐expressing cells. Co‐expression of LH and TSH was extremely rare (< 1%) and unchanged over the last month of gestation or HPD. The increase of gonadotrophs expressing FSH only or LH and FSH was attenuated by HPD. Therefore, the proportions of somatotrophs, lactotrophs and corticotrophs are regulated independently of hypothalamic input in the late gestation fetal pituitary. In marked contrast, the determination of the thyrotroph and gonadotroph lineages over the same time period is subject to complex mechanisms involving hypothalamic factors, which inhibit differentiation and/or proliferation of thyrotrophs, but stimulate gonadotrophs down the FSH lineage. Development of a distinct population of gonadotrophs, expressing only LH, appears to be subject to alternative mechanisms.
Conduction velocity is regulated by sodium channel inactivation in unmyelinated axons innervating the rat cranial meninges
Authors: De Col Roberto , Messlinger Karl , Carr Richard W.
Published: December 2007

Axonal conduction velocity varies according to the level of preceding impulse activity. In unmyelinated axons this typically results in a slowing of conduction velocity and a parallel increase in threshold. It is currently held that Na+–K+‐ATPase‐dependent axonal hyperpolarization is responsible for this slowing but this has long been equivocal. We therefore examined conduction velocity changes during repetitive activation of single unmyelinated axons innervating the rat cranial meninges. In direct contradiction to the currently accepted postulate, Na+–K+‐ATPase blockade actually enhanced activity‐induced conduction velocity slowing, while the degree of velocity slowing was curtailed in the presence of lidocaine (10–300 μm) and carbamazepine (30–500 μm) but not tetrodotoxin (TTX, 10–80 nm). This suggests that a change in the number of available sodium channels is the most prominent factor responsible for activity‐induced changes in conduction velocity in unmyelinated axons. At moderate stimulus frequencies, axonal conduction velocity is determined by an interaction between residual sodium channel inactivation following each impulse and the retrieval of channels from inactivation by a concomitant Na+–K+‐ATPase‐mediated hyperpolarization. Since the process is primarily dependent upon sodium channel availability, tracking conduction velocity provides a means of accessing relative changes in the excitability of nociceptive neurons.