			Home About us Contact

Regular Arrangement (regular + arrangement)

Distribution by Scientific Domains

Medical Sciences	62%

Selected Abstracts

Regular arrangement of periodates bound to lysozyme

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2005
Jan Ondrá
The structure of tetragonal hen egg-white lysozyme soaked in a periodate solution has been determined to a resolution of 1.8,Å. Four high-occupancy periodate positions have been identified on the basis of the anomalous signal of the I atoms. The four periodates exhibit a regular rectangular arrangement on the surface of the lysozyme molecule. No similar regular arrangement was found either in lysozyme crystals soaked in other heavy-atom anions or in other structures from the Protein Data Bank. Depending on their position on the surface of the protein, the periodate ions deviate to a varying extent from ideal octahedral geometry. [source]

ENDOSCOPIC IDENTIFICATION OF HELICOBACTER PYLORI GASTRITIS IN CHILDREN

DIGESTIVE ENDOSCOPY, Issue 2 2010
Nao Hidaka
Aim:, The role of endoscopic findings in deciding whether to biopsy the gastric mucosa of children remains unclear. The present study attempted, for the first time, to identify the value of endoscopic features for diagnosis of Helicobacter pylori (Hp) infection in children. Methods:, Hp status of consecutive children receiving esophagogastroduodenoscopy (EGD) was established by combinations of histology, 13C-urea breath test, and serum Hp immunoglobulin (Ig)G antibody. After routine EGD using a conventional endoscope, the presence of RAC (regular arrangement of collecting venules) was scored by close observation, which was carried out at two sites of lower corpus lesser curvature and upper corpus greater curvature. RAC-positive was defined as the presence of minute red points in a regular pattern. Antral nodularity was also scored as present/absent. Results:, Eighty-seven consecutive children (38 boys, median age 13 years, range 9,15 years) were evaluated; 25 (29%) were Hp positive. Antral nodularity was seen in 21 (84%) all of whom were Hp positive. The RAC-negative pattern based on examination of the upper and lower corpus yielded a sensitivity, specificity, positive predictive value and negative predictive value for the presence of Hp infection of 100%, 90%, 81%, and 100%. Magnifying endoscopy confirmed that the RAC pattern corresponded to collecting venules in the gastric corpus. Conclusions:, The absence of RAC pattern suggests that gastric mucosa biopsies should be taken despite otherwise normal-appearing gastric mucosa for the diagnosis of Hp infection in children. [source]

Organically Functionalized Mesoporous Silica by Co-structure-Directing Route

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Chuanbo Gao
Abstract This article provides a brief overview of functional mesoporous silica materials synthesized by the co-structure-directing route, which is distinct from conventional synthesis strategies. In these systems, organosilane serves as the co-structure-directing agent (CSDA), which provides critical interactions between the template and organic part of the organosilane to form mesostructures, thus retaining the organic groups on the pore surface after removal of the template by extraction. i) The formation of anionic-surfactant-templated mesoporous silicas (AMSs) has been achieved by the co-structure-directing route, which leads to a variety of mesostructures, porous properties and morphologies. ii) Other co-structure-directing systems for synthesizing mesoporous silicas have also been achieved, including systems using cationic surfactants and non-surfactants, and systems using DNA for constructing nanofibers and DNA,silica liquid crystalline complexes. iii) Evidence for the regular arrangement of functional groups on the pore surface resulted from the co-structure-directing effect has been discussed. Also included is a brief description of the application, future requirements, and trends in the development of mesoporous materials by the co-structure-directing route. [source]

Comparison of High Resolution Magnifying Endoscopy and Standard Videoendoscopy for the Diagnosis of Helicobacter pylori Gastritis in Routine Clinical Practice: A Prospective Study

HELICOBACTER, Issue 1 2009
Can Gonen
Abstract Background:, It has been shown that standard endoscopic features often labeled as gastritis has a poor correlation with histopathology. Recently, high resolution magnifying endoscopy has been reported to be an effective method to diagnose gastritis. The aim of the present study was to compare standard endoscopy with magnifying endoscopy for the diagnosis of Helicobacter pylori gastritis, and to determine whether gastritis can be diagnosed based on findings at magnification endoscopy. Materials and Methods:, A total of 129 patients were enrolled into the study. Erythema, erosions, prominent area gastrica, nodularity, and regular arrangement of collecting venules (RAC) were investigated by standard endoscopy. Standard endoscopy was followed by magnifying endoscopy in all patients, and repeated in 55 patients after indigo carmine spraying. Results:, None of the standard endoscopic features showed a sensitivity of more than 70% for H. pylori gastritis, except RAC pattern analysis. Absence of a corporal RAC pattern had 85.7% sensitivity and 82.8% specificity for predicting H. pylori infection. Under magnification, the sensitivity and specificity of regular corporal pattern (regular collecting and capillary vascular structures with gastric pits resembling pinholes) for predicting normal histology were 90.3% and 93.9%, respectively. Loss of collecting venules, or both collecting and capillary structures was correlated with chronic inflammation and activity. With the progression of mucosal atrophy, irregular collecting venules became visible. The values for irregularly arranged antral ridge pattern for the prediction of antral gastritis were 89.3% and 65.2%, respectively. Indigo carmine staining increased sensitivity and specificity up to 97.6% and 100% for corporal gastritis, and up to 88.4% and 75.0% for antral gastritis, respectively. Indigo carmine staining significantly increases the detection of intestinal metaplasia. Conclusions:, High resolution magnifying is superior to standard endoscopy for the diagnosis of H. pylori gastritis, and identification of specific histopathologic features such as atrophy and intestinal metaplasia seems possible. [source]

Discrimination of Normal Gastric Mucosa from Helicobacter pylori Gastritis using Standard Endoscopes and a Single Observation Site: Studies in Children and Young Adults

HELICOBACTER, Issue 2 2004
Yoshiko Nakayama
ABSTRACT Background., In the Helicobacter pylori -negative normal stomach, collecting venules are visible in the gastric corpus as numerous minute points. This finding has been termed ,regular arrangement of collecting venules' (RAC). The aim of the present study was to investigate the reliability of the presence of the RAC pattern for discrimination of normal gastric mucosa from H. pylori gastritis in pediatric patients. Methods., Fifty-two consecutive children, adolescents and young adults (male:female 24 : 28; median age 15 years, range 8,29 years) referred for endoscopy and assessed for H. pylori infection were prospectively studied. The lower lesser curvature of the corpus near the incisura was evaluated for the RAC pattern using a standard endoscope with the tip close to, but not in contact with, the gastric surface. Gastric biopsies were taken after the endoscopic observation. Results., In all the 29 RAC-positive patients, active H. pylori gastritis was absent, whereas H. pylori gastritis was found in 20 of 23 RAC-negative patients (86.9%). Conclusions., Identification of the RAC pattern at the lower lesser curvature of the corpus using close observation with a standard endoscope proved to be an effective and practical marker to discriminate normal histology from H. pylori gastritis among both children and young adults. Absence of the RAC pattern should prompt gastric mucosal biopsies despite otherwise normal-appearing gastric mucosa. [source]

Characteristic endoscopic and magnified endoscopic findings in the normal stomach without Helicobacter pylori infection

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 1 2002
KAZUYOSHI YAGI
Abstract Background and Aims: The aim of this study was to clarify the endoscopic features of the Helicobacter pylori (H. pylori) -free stomach by examining the arrangement of minute points visible on the corpus. Since these points were clarified by magnifying endoscopy as collecting venules, this finding was termed ,regular arrangement of collecting venules (RAC)'. The findings from more endoscopic studies are presented and the differences between magnified views of the normal and H. pylori -infected corpus and antrum are described in particular. Methods: The study group consisted of 557 patients who were subjected to endoscopy and checked for H. pylori. The RAC in each patient was assessed. Magnifying endoscopy in 301 patients was used to examine the corpus and in 94 patients to examine the antrum. Results: One hundred and fifty-eight patients had normal stomachs without H. pylori. We diagnosed 389 patients with H. pylori gastritis. In 10 patients H. pylori was not detected, but inflammation was present. Of the 158 patients with H. pylori -negative normal stomachs, 151 had RAC. As a determinant of the normal stomach without H. pylori infection, the presence of RAC had 93.8% sensitivity and 96.2% specificity. All 30 patients with H. pylori -negative normal stomachs had a well-defined ridge pattern (wDRP) on the antrum as observed under magnifying endoscopy. As a determinant of the normal stomach without H. pylori infection, wDRP had a specificity of 100%, but a sensitivity of only 54.5%. Conclusions: The presence of RAC is characteristic of a normal stomach without H. pylori. Magnified views of the normal antrum were different from that of the normal corpus. [source]

Regular arrangement of periodates bound to lysozyme

Remodelling of collagen fibrils and proteoglycans in the zebrafish cornea during development

ACTA OPHTHALMOLOGICA, Issue 2007
S AKHTAR
Purpose: Collagen fibrils and proteoglycans are the main components of the corneal extracellular matrix and corneal transparency depends crucially on their proper organisation. We investigated their formation and arrangement in the developing cornea of the zebrafish, a major model of vertebrate development and genetic disease. Methods: We employed thin-section electron microscopy to investigate the ultrastructure of the zebrafish cornea at different stages of development. Results: Layering of the zebrafish cornea into an epithelium, Bowman's layer, stroma and endothelium was observed by 72 hours post-fertilization. At this stage, the stroma contained orthogonally arranged collagen fibrils and small proteoglycans. The density of proteoglycans increased gradually throughout subsequent development. In the stroma of 2 week old larvae, the collagen fibrils were organized into thin lamellae for the first time and were separated by very large, randomly distributed proteoglycans. At 4 weeks, a regular arrangement of proteoglycans around the collagen fibrils was observed for the first time and the lamellae also thickened. Conclusions: This is the first report of collagen fibril and proteoglycan development in the zebrafish cornea and it directly correlates collagen fibril and proteoglycan organisation of the zebrafish cornea with that of the human cornea. The similarities between the two species, including the possession of a Bowman layer, suggest that the zebrafish could serve as a model for the genetics of human corneal development and inherited disease. [source]