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Biomedical subjects

Bo Shen

Publications and source records attributed to Bo Shen.

69 records · Page 4Linked to original sources
PubMed2003

sal1 determines the number of aleurone cell layers in maize endosperm and encodes a class E vacuolar sorting protein.

A microscopy-based screen of a large collection of maize Mutator (Mu) transposon lines identified the supernumerary aleurone layers 1-1 (sal1-1) mutant line carrying up to seven layers of aleurone cells in defective kernel endosperm compared with only a single layer in wild-type grains. Normal, well filled endosperm that is homozygous for the sal1-1 mutant allele contains two to three layers of aleurone cells. Cloning of the sal1 gene was accomplished by using Mu tagging, and the identity of the cloned gene was confirmed by isolating an independent sal1-2 allele by reverse genetics. Homozygous sal1-2 endosperm has two to three layers of aleurone cells in normal, well filled grains. In situ hybridization experiments reveal that the sal1 gene is ubiquitously expressed in vegetative as well as zygotic grain tissues, with no difference being detected between aleurone cells and starchy endosperm cells. Northern blot analysis failed to detect the sal1-2 transcript in leaves of homozygous plants, suggesting that the allele is a true sal1 knockout allele. The sal1 gene encodes a homologue of the human Chmp1 gene, a member of the conserved family of the class E vacuolar protein sorting genes implicated in membrane vesicle trafficking. In mammals, CHMP1 functions in the pathway targeting plasma membrane receptors and ligands to lysosomes for proteolytic degradation. Possible roles for the function of the sal1 gene in aleurone signaling, including a defect in endosome trafficking, are discussed.

Amino Acid Sequence↗
PubMed2003

Modified pouchitis disease activity index: a simplified approach to the diagnosis of pouchitis.

PURPOSE: Pouchitis is the most common complication of ileal pouch-anal anastomosis for ulcerative colitis. Our previous study suggested that symptoms alone are not reliable for the diagnosis of pouchitis. The most commonly used diagnostic instrument is the 18-point pouchitis disease activity index consisting of three principal component scores: symptom, endoscopy, and histology. Despite its popularity, the pouchitis disease activity index has mainly been a research tool because of costs of endoscopy (especially with histology), complexity in calculation, and time delay in determining histology scores. It is not known whether pouch endoscopy without biopsy can reliably diagnose pouchitis in symptomatic patients. The aim of the present study was to determine whether omitting histologic evaluation from the pouchitis disease activity index significantly affects the sensitivity and specificity of diagnostic criteria for pouchitis. METHODS: Ulcerative colitis patients with an ileal pouch-anal anastomosis and symptoms suggestive of pouchitis were evaluated. Patients with chronic refractory pouchitis and Crohn's disease were excluded. Patients with pouchitis disease activity index scores of seven or more were diagnosed as having pouchitis. Different diagnostic criteria were compared on the basis of the pouchitis disease activity index component scores. Nonparametric receiver-operating-characteristic curves were used to measure proposed pouchitis scores' diagnostic accuracy compared with diagnosis from the pouchitis disease activity index. The receiver-operating-characteristic area under the curve measured how much these diagnostic strategies differed from each other. RESULTS: Fifty-eight consecutive symptomatic patients were enrolled; 32 (55 percent) patients were diagnosed with pouchitis. With the use of the pouchitis disease activity index as a criterion standard, the use of only symptom and endoscopy scores (modified pouchitis disease activity index) produced an area under the curve of 0.995. Establishing a cut-point of five or more for diseased patients resulted in a sensitivity equal to 97 percent and specificity equal to 100 percent. CONCLUSIONS: Diagnosis based on the modified pouchitis disease activity index offers similar sensitivity and specificity when compared with the pouchitis disease activity index for patients with acute or acute relapsing pouchitis. Omission of endoscopic biopsy and histology from the standard pouchitis disease activity index would simplify pouchitis diagnostic criteria, reduce the cost of diagnosis, and avoid delay associated with determining histology score, while providing equivalent sensitivity and specificity.

Endoscopy, Gastrointestinal↗
PubMed2003

A cost-effectiveness analysis of diagnostic strategies for symptomatic patients with ileal pouch-anal anastomosis.

OBJECTIVE: Pouchitis is often diagnosed based on symptoms and empirically treated with antibiotics (treat-first strategy). However, symptom assessment alone is not reliable for diagnosis, and an initial evaluation with pouch endoscopy (test-first strategy) has been shown to be more accurate. Cost-effectiveness of these strategies has not been compared. The aim of this study was to compare cost-effectiveness of different clinical approaches for patients with symptoms suggestive of pouchitis. METHODS: Pouchitis was defined as pouchitis disease activity index scores > or =7. The frequency of pouchitis in symptomatic patients with ileal pouch was estimated to be 51%; the efficacy for initial therapy with metronidazole (MTZ) and ciprofloxacin (CIP) was 75% and 85%, respectively. Cost estimates were obtained from Medicare reimbursement data. RESULTS: Six competing strategies (MTZ trial, CIP trial, MTZ-then-CIP trial, CIP-then-MTZ trial, pouch endoscopy with biopsy, and pouch endoscopy without biopsy) were modeled in a decision tree. Costs per correct diagnosis with appropriate treatment were $194 for MTZ trial, $279 for CIP trial, $208 for MTZ-then-CIP trial, $261 for CIP-then-MTZ trial, $352 for pouch endoscopy with biopsy, and $243 for pouch endoscopy without biopsy. Of the two strategies with the lowest cost, the pouch endoscopy without biopsy strategy costs $50 more per patient than the MTZ trial strategy but results in an additional 15 days for early diagnosis and thus initiation of appropriate treatment (incremental cost-effectiveness ratio $3 per additional day gained). The results of base-case analysis were robust in sensitivity analyses. CONCLUSIONS: Although the MTZ-trial strategy had the lowest cost, the pouch endoscopy without biopsy strategy was most cost-effective. Therefore, based on its relatively low cost and the avoidance of both diagnostic delay and adverse effects associated with unnecessary antibiotics, pouch endoscopy without biopsy is the recommended strategy among those tested for the diagnosis of pouchitis.

Aged↗
PubMed2003

Diagnosis and treatment of patients with pouchitis.

Pouchitis is the most common long-term complication of ileal pouch-anal anastomosis in patients with underlying ulcerative colitis. Clinical symptoms of pouchitis are not specific, and they can be caused by other conditions such as rectal cuff inflammation and irritable pouch syndrome. Therefore, to make an accurate diagnosis, endoscopic evaluation together with symptom assessment is necessary. Among five available treat-first and test-first strategies, the initial approach with pouch endoscopy without histology was the most cost-effective strategy for the diagnosis of pouchitis. On the basis of clinical course, pouchitis can be classified into acute, relapsing and chronic forms. Pouchitis can also be classified into three categories based on the response to antibacterial therapy: antibacterial-responsive; antibacterial-dependent; and antibacterial-resistant. Metronidazole and ciprofloxacin are both effective in treating acute pouchitis. Although antibacterial therapy can induce and maintain remission, probiotics such as VSL#3 can also be used as to maintain clinical remission and prevent relapse in patients with relapsing or chronic pouchitis. For patients with chronic pouchitis that is resistant to antibacterials, therapy with anti-inflammatory agents and immunomodulators is often required.

Acute Disease↗
PubMed2003

Molecule action mechanisms of NM-3 on human gastric cancer SGC-7901 cells in vivo or in vitro.

AIM: To study the molecule action mechanisms of NM-3 on the growth of human gastric cancer SGC-7901 cells in vivo or in vitro. METHODS: SGC-7901 from human non-differentiated gastric cancer cell line was cultured with NM-3 at 100 mg/ml for 24 h. We observed its inhibitory rate and the density of micro-vascular growth in grafted mice with human gastric cancer SGC-7901. The apoptosis of human gastric cancer SGC-7901 was revealed in NM-3 treatment group by using terminal deoxynucleotidyl transferase-mediated deoxy-uridine triphosphate-fluorescene nick end labeling (TUNEL) method and flow cytometry analysis. RESULTS: The growth of SGC-7901 cells was markedly inhibited compared with control growp, which was smaller than that in normal saline control group (4.17 g+/-0.22 g vs 9.45 g+/-1.38 g, P<0.01). The level of apoptosis of human gastric cell line SGC-7901 was obviously increased in NM-3 treatment group at 1 mg.L(-1) for 24 h. NM-3 inducing apoptotic index in NM-3 plus carboplatin group was 3.5 times that of carboplatin control group (TUNEL: 27.98+/-6.12% vs 12.94+/-2.12%, FACScan: 26.86+/-5.69% vs 11.86+/-1.09%, P<0.01). Western blot analysis showed that the apoptotic index of human gastric cancer was elevated for 12, 24 and 36 h with an evident time-effect relationship in groups at 100 mg.L(-1). NM-3 enhanced the inhibitive effects and sensitivity of chemotherapy for human gastric cancer in nude mice. These results suggested that NM-3 played a key inhibitive role in the growth of grafted human gastric cancer in nude mice. CONCLUSION: NM-3 can inhibit the growth of human gastric cancer cell line SGC-7901, and enhance the sensitivity of carboplatin on SGC-7901 and induced its apoptosis.

Animals↗
PubMed2003

[QTLs mapping of leaf traits and root vitality in a recombinant inbred line population of rice].

By employing a recombinant inbred line (RIL) population of 247 lines derived from an inidca-indica cross Zhenshan 97B x Milyang 46, a linkage map consisting of 158 DNA markers was constructed and used for the determination of QTLs conditioning five leaf traits and root exudates. The leaf traits analyzed were leaf area, leaf length, leaf width, leaf perimeter and leaf length/width ratio measured on top first leaf, top second and top third leaves. The RIL population showed transgressive segregation on each trait, and highly significant or significant positive correlations were observed between all traits except between leaf length and width, and between leaf perimeter and length/width ratio. A total of 24 QTLs located in 9 intervals were detected to have significant additive effects for leaf traits analyzed, with LOD scores ranging 2.9-11.8 and 4.0%-32.5% phenotypic variation explained for a single QTL. Clustering of QTLs for leaf traits was evident. In interval RM197-RZ516 on chromosome 6, 2 QTLs for leaf length, 2 QTLs for leaf width and 3 QTLs for leaf length/width ratio of different leaves were detected, among which the alleles for increasing trait values were from Zhenshan 97B for leaf length and leaf length/width ratio, and from Milyang 46 for leaf width. In interval RM1-RG532 on chromosome 1,2 QTLs for leaf length and 2 QTLs for leaf perimeter were detected on top first leaf and top second leaf, respectively, and all the alleles for increasing trait values were from Milyang 46. In this interval, larger additive effects were observed for QTLs detected on top first leaf than at top second leaf. In interval RZ667-B10B on chromosome 6, a QTL for leaf perimeter of top second leaf was detected, accounting for 8.0% phenotypic variation. In intervals RZ66-RM264 and RG81-RM313 on chromosome 8 and 12, each QTL was detected for leaf length of top third leaf and explained for 9.0% and 15.3% phenotypic variation, respectively. Epistasis analysis detected 56 and 4 significant additive-by-additive interactions for leaf traits and root vitality, explaining 2.7% to 13.7% and 6.8% to 14.9% of the total phenotypic variation, respectively. On comparison with QTLs for yield traits detected in the same population previously, it was found that the majority of QTLs for leaf traits and root vitality and those for yield traits were located in similar intervals. Fine mapping of QTLs for both leaf and yield traits in these chromosomal regions would facilitate investigations of the source-sink relationship in rice.

Chromosome Mapping↗
PubMed2002

Mannopeptimycins, novel antibacterial glycopeptides from Streptomyces hygroscopicus, LL-AC98.

A series of novel antibiotics with activity against methicillin-resistant staphylococci and vancomycin-resistant enterococci has been purified, and their structures have been characterized using spectroscopic analyses and chemical conversions. These antibiotics, designated mannopeptimycins alpha-epsilon (1-5), are glycosylated cyclic hexapeptides containing two stereoisomers of an unprecedented amino acid, alpha-amino-beta-[4'-(2'-iminoimidazolidinyl)]-beta-hydroxypropionic acid (Aiha), as a distinguishing feature. The cyclic peptide core of these antibiotics is attached to a mannosyl monosaccharide moiety in 2 and to mannosyl monosaccharide and disaccharide moieties in 1, 3, 4, and 5. The presence and position of an isovaleryl group in the terminal mannose (Man-B) in 3-5 are critical for retaining antibacterial potency.

Anti-Bacterial Agents↗
PubMed2002

Paneth cell trypsin is the processing enzyme for human defensin-5.

The antimicrobial peptide human alpha-defensin 5 (HD5) is expressed in Paneth cells, secretory epithelial cells in the small intestine. Unlike other characterized defensins, HD5 is stored in secretory vesicles as a propeptide. The storage quantities of HD5 are approximately 90 450 microg per cm2 of mucosal surface area, which is sufficient to generate microbicidal concentrations in the intestinal lumen. HD5 peptides isolated from the intestinal lumen are proteolytically processed forms--HD5(56-94) and HD5(63-94)--that are cleaved at the Arg55-Ala56 and Arg62-Thr63 sites, respectively. We show here that a specific pattern of trypsin isozymes is expressed in Paneth cells, that trypsin colocalizes with HD5 and that this protease can efficiently cleave HD5 propeptide to forms identical to those isolated in vivo. By acting as a prodefensin convertase in human Paneth cells, trypsin is involved in the regulation of innate immunity in the small intestine.

Amino Acid Sequence↗
PubMed2002

Cytokeratin expression patterns in noncardia, intestinal metaplasia-associated gastric adenocarcinoma: implication for the evaluation of intestinal metaplasia and tumors at the esophagogastric junction.

BACKGROUND: Barrett esophagus (BE)/Barrett adenocarcinoma and distal gastric intestinal metaplasia (IM)/adenocarcinoma are similar histologically, but they differ in their clinical presentation, epidemiology, and pathogenesis. Differentiating BE from gastric IM and Barrett adenocarcinoma from gastric adenocarcinoma is difficult, especially when IM is short or tumors are large and involve both sides of the esophagogastric junction. Previously, the authors identified unique cytokeratin (CK) immunoreactivity patterns that were associated strongly with BE and Barrett adenocarcinoma. The specificity of CK7 and CK20 (CK7/20) expression patterns in patients with IM-associated gastric adenocarcinoma, which is distinct epidemiologically from BE/Barrett adenocarcinoma, has not been evaluated. The objective of the current study was to evaluate the CK7/20 expression patterns in noncardia, IM-associated gastric adenocarcinoma in a Chinese population with a low risk for BE and esophageal adenocarcinoma and a high risk for Helicobacter pylori infection and gastric carcinoma. METHODS: Endoscopic biopsy specimens of gastric IM and adjacent tumor from 50 consecutive patients with advanced noncardia gastric carcinoma were immunostained for CK7 and CK20. Clinical and endoscopic features and H. pylori status were documented. Two gastrointestinal pathologists, blinded to clinical and endoscopic data, independently assessed CK7/20 immunohistochemistry. RESULTS: H. pylori infection was present in 43 of 50 patients (86%). In the area of IM, patchy CK7 staining was seen in 9 patients (18%), and diffuse CK20 staining was seen in all 50 patients (100%). The BE CK7/20 pattern characterized by CK7 staining in superficial and deep glands and the CK20 staining in surface epithelium was not seen in any of the 50 patients. Only one patient (2%) demonstrated a CK7 positive/CK20 negative immunophenotype characteristic of Barrett adenocarcinoma. The remaining 49 patients (98%) showed non-Barrett adenocarcinoma patterns of CK7/20 staining, i.e., a CK7 positive/CK20 positive pattern was seen in 33 patients (66%), a CK7 negative/CK20 positive pattern was seen in 12 patients (24%), and a CK7 negative/CK20 negative pattern was seen in 4 patients (8%). CONCLUSIONS: In a patient population without risk factors for the development of BE/esophageal adenocarcinoma, the CK7/20 pattern characteristic of BE was not present in gastric IM adjacent to adenocarcinoma, and the CK7/20 pattern characteristic of Barrett adenocarcinoma also was extremely rare. These results support the hypothesis that, despite the presence of intestinalized mucosa in both disorders, BE/Barrett adenocarcinoma and gastric IM/adenocarcinoma are two distinct clinical entities with unique demographic, clinical, and CK immunophenotypic findings. These results may have application to the evaluation of patients with IM and adenocarcinoma arising at the esophagogastric junction.

Adenocarcinoma↗
PubMed2002

High free-methionine and decreased lignin content result from a mutation in the Arabidopsis S-adenosyl-L-methionine synthetase 3 gene.

As an approach to understand the regulation of methionine (Met) metabolism, Arabidopsis Met over-accumulating mutants were isolated based on their resistance to selection by ethionine. One mutant, mto3, accumulated remarkably high levels of free Met - more than 200-fold that observed for wild type - yet showed little or no difference in the concentrations of other protein amino-acids, such as aspartate, threonine and lysine. Mutant plants did not show any visible growth differences compared with wild type, except a slight delay in germination. Genetic analysis indicated that the mto3 phenotype was caused by a single, recessive mutation. Positional cloning of this gene revealed that it was a novel S-adenosylmethionine synthetase, SAMS3. A point mutation resulting in a single amino-acid change in the ATP binding domain of SAMS3 was determined to be responsible for the mto3 phenotype. SAMS3 gene expression and total SAMS protein were not changed in mto3; however, both total SAMS activity and S-adenosylmethionine (SAM) concentration were decreased in mto3 compared with wild type. Lignin, a major metabolic sink for SAM, was decreased by 22% in mto3 compared with wild type, presumably due to the reduced supply of SAM. These results suggest that SAMS3 has a different function(s) in one carbon metabolism relative to the other members of the SAMS gene family.

Arabidopsis↗
PubMed2002

Engineering for drought avoidance: expression of maize NADP-malic enzyme in tobacco results in altered stomatal function.

Water is a principal limitation to agricultural production during drought and in arid regions of the world. Mechanisms that plants use to cope with drought can be grouped into two different strategies: drought tolerance and drought avoidance. Previous efforts toward engineering plants for improved performance during drought have focused on drought tolerance, the ability to adjust to dry conditions. This report addresses the engineering of a drought-avoidance phenotype, which allows for the conservation of water during plant growth. The majority of water lost from plants occurs through stomata. When stomata are open, potassium, chloride and/or malate are present at high concentrations in guard cells. The accumulation of large numbers of ions during stomatal opening increases the turgor pressure of the guard cells, which results in increased pore size. Expression of a single gene from maize, NADP-malic enzyme (ME), which converts malate and NADP to pyruvate, NADPH, and CO(2), resulted in altered stomatal behaviour and water relations in tobacco. The ME-transformed plants had decreased stomatal conductance and gained more fresh mass per unit water consumed than did the wild type, but they were similar to the wild type in their growth and rate of development. Providing chloride via the transpiration stream partially reversed the effects of ME expression on stomatal aperture size, which is consistent with the interpretation that expression of ME altered malate metabolism in guard cells. These results suggest a role for malic enzyme in the mechanism of stomatal closure, as well as a potential mechanism for genetically altering plant water use.

Acclimatization↗
PubMed2002

Irritable pouch syndrome: a new category of diagnosis for symptomatic patients with ileal pouch-anal anastomosis.

OBJECTIVE: Pouchitis often is diagnosed based on symptoms alone. However, increased stool frequency, urgency, and abdominal pain could be due to a condition resembling irritable bowel syndrome. This study was designed to assess the etiology of bowel symptoms using the Pouchitis Disease Activity Index (PDAI). METHODS: Symptoms, endoscopy, and histology were assessed in 61 consecutive symptomatic patients with ulcerative colitis after ileal pouch-anal anastomosis. Pouchitis was defined as a PDAI score of > or = 7, cuffitis was defined as endoscopic and histological inflammation of the rectal cuff and no inflammation of the pouch, and irritable pouch syndrome (IPS) was defined as symptoms with a PDAI of <7 and the absence of cuffitis. RESULTS: Thirty-one patients (50.8%) had pouchitis, four (6.5%) had cuffitis, and 26 (42.6%) had IPS. Demographics were similar in the three groups. Increased stool frequency, urgency, and abdominal cramps were the most common symptoms in the three groups. Rectal bleeding was seen only in cuffitis (p < 0.001). No patient in the three groups had fever. Twenty-seven patients (87.1%) with pouchitis responded to a 2-wk course of ciprofloxacin or metronidazole with a reduction in PDAI scores of > or = 3. All four patients with cuffitis responded to topical hydrocortisone or mesalamine with a reduction in the PDAI symptom component score of > or = 1. Twelve patients with IPS (46.2%) responded to antidiarrheal, anticholinergic, and/or antidepressant therapies with a reduction in the PDAI symptom component score of > or = 1, whereas the remaining patients had persistent symptoms despite therapy. CONCLUSIONS: A substantial number of symptomatic patients after ileal pouch-anal anastomosis do not meet the diagnostic criteria for either pouchitis or cuffitis and have been classified as having IPS. There is an overlap of symptoms among patients with pouchitis, cuffitis, and IPS, and endoscopic evaluation can differentiate among these groups. Distinction between these three groups has therapeutic implications.

Adult↗
PubMed2002

[Cloning and sequence analysis of full-length trypsin cDNA of Culex pipiens pallens].

The expression difference of trypsin gene between deltamethrin-resistant strain and -susceptible strain of Culex pipiens pallens was further investigated, and the results showed that the expression of trypsin gene were respectively 4.3 and 3.9 fold more in the resistant strain than in the susceptible strain, by reverse Northern blot and Northern blot assays. A full-length trypsin cDNA of 909 base pairs (GenBank/NCBI AY034060) with an open reading frame of 786 base pairs was cloned from the constructed cDNA library by the rapid amplification of cDNA ends, and the deduced protein of 261 amino acids was 55% homologous with Anopheles gambiae trypsin.

Amino Acid Sequence↗
PubMed2002

[Research on slit lamp bio-microscope image analysis system].

Slit lamp bio-microscope image analysis system can provide objective and quantitative diagnosis evidences for ophthalmologists and make available efficient storing, management and intercourse of sufferer information and diagnosis results. In this paper, the system is discussed on its devices, software structure, analysis process and algorithm.

Algorithms↗