AIM:To design and validate broad-range 16S rRNA primers for use in high throughput sequencing to classify bacteria isolated from the human foregut microbiome.METHODS:A foregut microbiome dataset was constructed using ...AIM:To design and validate broad-range 16S rRNA primers for use in high throughput sequencing to classify bacteria isolated from the human foregut microbiome.METHODS:A foregut microbiome dataset was constructed using 16S rRNA gene sequences obtained from oral,esophageal,and gastric microbiomes produced by Sanger sequencing in previous studies represented by 219 bacterial species.Candidate primers evaluated were from the European rRNA database.To assess the effect of sequence length on accuracy of classification,16S rRNA genes of various lengths were created by trimming the full length sequences.Sequences spanning various hypervariable regions were selected to simulate the amplicons that would be obtained using possible primer pairs.The sequences were compared with full length 16S rRNA genes for accuracy in taxonomic classification using online software at the Ribosomal Database Project (RDP).The universality of the primer set was evaluated using the RDP 16S rRNA database which is comprised of 433 306 16S rRNA genes,represented by 36 phyla.RESULTS:Truncation to 100 nucleotides(nt)downstream from the position corresponding to base 28 in the Escherichia coli 16S rRNA gene caused misclassification of 87(39.7%)of the 219 sequences,compared with misclassification of only 29(13.2%)sequences with truncation to 350 nt.Among 350-nt sequence reads within various regions of the 16S rRNA gene,the reverse read of an amplicon generated using the 343F/798R primers had the least(8.2%)effect on classification.In comparison,truncation to 900 nt mimicking single pass Sanger reads misclassified 5.0%of the 219 sequences.The 343F/798R amplicon accurately assigned 91.8%of the 219 sequences at the species level.Weighted by abundance of the species in the esophageal dataset,the 343F/798R amplicon yielded similar classification accuracy without a significant loss in species coverage(92%).Modification of the 343F/798R primers to 347F/803R increased their universality among foregut species.Assuming that a typicalpolymerase chain reaction can tolerate 2 mismatches between a primer and a template,the modified 347F and 803R primers should be able to anneal 98%and 99.6%of all 16S rRNA genes in the RDP database.CONCLUSION:347F/803R is the most suitable pair of primers for classification of foregut 16S rRNA genes but also possess universality suitable for analyses of other complex microbiomes.展开更多
Gastroesophageal reflux disease(GERD) is a frequently encountered disorder. Obesity is an important risk factor for GERD, and there are several pathophysiologic mechanisms linking the two conditions. For obese patient...Gastroesophageal reflux disease(GERD) is a frequently encountered disorder. Obesity is an important risk factor for GERD, and there are several pathophysiologic mechanisms linking the two conditions. For obese patients with GERD, much of the treatment effort is focused on weight loss and its consistent benefit to symptoms, while there is a relative lack of evidence regarding outcomes after novel or even standard medical therapy is offered to this population. Physicians are hesitant to recommend operative anti-reflux therapy to obese patients due to the potentially higher risks and decreased efficacy, and these patients instead are often considered for bariatric surgery. Bariatric surgical approaches are broadening, and each technique has emerging evidence regarding its effect on both the risk and outcome of GERD. Furthermore, combined antireflux and bariatric options are now being offered to obese patients with GERD. However, currently Rouxen-Y gastric bypass remains the most effective surgical treatment option in this population, due to its consistent benefits in both weight loss and GERD itself. This article aims to review the impact of both conservative and aggressive approaches of obesity treatment on GERD.展开更多
The prevalence of type 2 diabetes is rising worldwide, especially in older adults. Diet and lifestyle, particularly plant-based diets, are ef-fective tools for type 2 diabetes prevention and management. Plant-based di...The prevalence of type 2 diabetes is rising worldwide, especially in older adults. Diet and lifestyle, particularly plant-based diets, are ef-fective tools for type 2 diabetes prevention and management. Plant-based diets are eating patterns that emphasize legumes, whole grains,vegetables, fruits, nuts, and seeds and discourage most or all animal products. Cohort studies strongly support the role of plant-based diets,and food and nutrient components of plant-based diets, in reducing the risk of type 2 diabetes. Evidence from observational and interven-tional studies demonstrates the benefits of plant-based diets in treating type 2 diabetes and reducing key diabetes-related macrovascular andmicrovascular complications. Optimal macronutrient ratios for preventing and treating type 2 diabetes are controversial; the focus should insteadbe on eating patterns and actual foods. However, the evidence does suggest that the type and source of carbohydrate （unrefined versus refined）,fats （monounsaturated and polyunsaturated versus saturated and trans）, and protein （plant versus animal） play a major role in the prevention andmanagement of type 2 diabetes. Multiple potential mechanisms underlie the benefits of a plant-based diet in ameliorating insulin resistance, in-cluding promotion of a healthy body weight, increases in fiber and phytonutrients, food-microbiome interactions, and decreases in saturated fat,advanced glycation endproducts, nitrosamines, and heme iron.展开更多
Vanishing bile duct syndrome(VBDS) is a group of rare disorders characterized by ductopenia,the progressive destruction and disappearance of intrahepatic bile ducts leading to cholestasis.Described in association with...Vanishing bile duct syndrome(VBDS) is a group of rare disorders characterized by ductopenia,the progressive destruction and disappearance of intrahepatic bile ducts leading to cholestasis.Described in association with medications,autoimmune disorders,cancer,transplantation,and infections,the specific mechanisms of disease are not known.To date,only 4 cases of VBDS have been reported in human immunodeficiency virus(HIV) infected patients.We report 2 additional cases of HIV-associated VBDS and review the features common to the HIV-associated cases.Presentation includes hyperbilirubinemia,normal liver imaging,and negative viral and autoimmune hepatitis studies.In HIV-infected subjects,VBDS occurred at a range of CD4+ T-cell counts,in some cases following initiation or change in antiretroviral therapy.Lymphoma was associated with two cases;nevirapine,antibiotics,and viral co-infection were suggested as etiologies in the other cases.In HIV-positive patients with progressive cholestasis,early identification of VBDS and referral for transplantation may improve outcomes.展开更多
AIM: To investigate the therapeutic potential of an RNA ligand (aptamer) specific for the catalytic ricin A-chain (RTA), the protective effects of a 31-nucleo-tide RNA aptamer (31RA), which formed a high affi nity com...AIM: To investigate the therapeutic potential of an RNA ligand (aptamer) specific for the catalytic ricin A-chain (RTA), the protective effects of a 31-nucleo-tide RNA aptamer (31RA), which formed a high affi nity complex with RTA, against ricin-induced toxicity in cellbased luciferase translation and cell cytotoxicity assays were evaluated. METHODS: To test the therapeutic potential of anti-RTA aptamers in Chinese hamster ovary (CHO) AA8 cells stably transfected with a tetracycline regulat-able promoter, ricin ribotoxicity was measured using luciferase and ricin-induced cytotoxicity was ascertained by MTS cell proliferation assay with tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium]. RESULTS: Inhibition of protein synthesis by ricin in CHO AA8 cells resulted in diminished luciferase activity and treatment with polyclonal antibody against degly-cosylated RTA (dgA) neutralized the inhibitory effects of ricin on luciferase activity and protected against ricin-induced cytotoxicity as measured by MTS assay. The 31RA anti-RTA aptamer inhibited the translation of luciferase mRNA in cell-free reticulocyte translation as- say. 31RA aptamer also partially neutralized the inhibitory effects of ricin on luciferase activity and partially protected against ricin-induced cytotoxicity in CHO AA8 cells. CONCLUSION: We have shown that anti-RTA RNA aptamer can protect against ricin ribotoxicity in cellbased luciferase and cell cytotoxicity assays. Hence, RNA aptamer that inhibits RTA enzymatic activity represents a novel class of nucleic acid inhibitor that has the potential to be developed as a therapeutic agent for the treatment of ricin intoxication.展开更多
AIM:To determine the expression and clinical significance of transcriptional intermediary factor 1 gamma (TIF1γ),Smad4 and transforming growth factor-beta (TGFβR) across a spectrum representing colorectal cancer (CR...AIM:To determine the expression and clinical significance of transcriptional intermediary factor 1 gamma (TIF1γ),Smad4 and transforming growth factor-beta (TGFβR) across a spectrum representing colorectal cancer (CRC) development.METHODS:Tissue microarrays were prepared from archival paraffin embedded tissue,including 51 colorectal carcinomas,25 tubular adenomas (TA) and 26 HPs,each with matched normal colonic epithelium.Immunohistochemistry was performed using antibodies against TIF1γ,Smad4 and TGFβ RⅡ.The levels of expression were scored semi-quantitatively (score 0-3 or loss and retention for Smad4).RESULTS:Overexpression of TIF1γ was detected in 5/26 (19%) HP;however,it was seen in a significantly higher proportion of neoplasms,15/25 (60%) TAs and 24/51 (47%) CRCs (P<0.05).Normal colonic mucosa,HP,and TAs showed strong Smad4 expression,while its expression was absent in 22/51 (43%) CRCs.Over-expression of TGFβ RⅡ was more commonly seen in neoplasms,13/25 (52%) TAs and 29/51 (57%) CRCs compared to 9/26 (35%) HP (P<0.05).Furthermore,there was a correlation between TIF1γ overexpression and Smad4 loss in CRC (Kendall tau rank correlation value=0.35,P<0.05).The levels of TIF1γ overexpression were significantly higher in stage Ⅲ than in stage Ⅰ and Ⅱ CRC (P<0.05).CONCLUSION:The findings suggest that over-expression of TIF1γ occurs in early stages of colorectal carcinogenesis,is inversely related with Smad4 loss,and may be a prognostic indicator for poor outcome.展开更多
AIM:To evaluate the ability of anti-ricin A-chain antibodies,delivered intracellularly,to protect against ricininduced cytotoxicity in RAW264.7 cells. METHODS:Anti-deglycosylated ricin A-chain antibody and RAC18 anti-...AIM:To evaluate the ability of anti-ricin A-chain antibodies,delivered intracellularly,to protect against ricininduced cytotoxicity in RAW264.7 cells. METHODS:Anti-deglycosylated ricin A-chain antibody and RAC18 anti-ricin A-chain monoclonal antibody were delivered intracellularly by encapsulating in liposomes or via conjugation with the cell-penetrating MTS-transport peptide.RAW264.7 cells were incubatedwith these antibodies either before or after ricin exposure.The changes in cytotoxicity were estimated by MTT assay.Co-localization of internalized antibody and ricin was evaluated by fluorescence microscopy. RESULTS:Internalized antibodies significantly increased cell viability either before or after ricin exposure compared to the unconjugated antibodies.Fluorescence microscopy confirmed the co-localization of internalized antibodies and ricin inside the cells. CONCLUSION:Intracellular delivery of antibodies to neutralize the ricin toxin after cellular uptake supports the potential use of cell-permeable antibodies for postexposure treatment of ricin intoxication.展开更多
Continuous-flow left ventricular assist devices(CF-LVADs)have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or,more recently,as destination ...Continuous-flow left ventricular assist devices(CF-LVADs)have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or,more recently,as destination therapy.However,its implantations carries a risk of complications including infection,device malfunction,arrhythmias,right ventricular failure,thromboembolic disease,postoperative and nonsurgical bleeding.A significant number of left ventricular assist devices(LVAD)recipients may experience recurrent gastrointestinal hemorrhage,mainly due to combination of antiplatelet and vitamin K antagonist therapy,activation of fibrinolytic pathway,acquired von Willebrand factor deficiency,and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump.Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions,extended hospital stays,multiple readmissions,and overall mortality.Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients,addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion.Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.展开更多
Primary adult hypertrophic pyloric stenosis is a rare but important cause of gastric outlet obstruction that may be misdiagnosed as idiopathic gastroparesis.Clinically,patients present with early satiety,abdominal ful...Primary adult hypertrophic pyloric stenosis is a rare but important cause of gastric outlet obstruction that may be misdiagnosed as idiopathic gastroparesis.Clinically,patients present with early satiety,abdominal fullness,nausea,epigastric discomfort and eructation.Permanent gastric retention of a video capsule endoscope is diagnostic in differentiating between the two diseases,in the absence of an organic gastric outlet obstruction.This case presents the longest video capsule retention in the medical literature to date.It is also the first case report of adult hypertrophic pyloric stenosis diagnosed with video capsule endoscopy or a computed tomography scan.Finally,an unusual"plugging"of the gastric outlet with free floating capsule has an augmented effect on disease physiology and on patient’s symptoms.展开更多
AIM: To identify the bacterial flora in conditions such as Barrett's esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora.METHODS: Using broad-range 16S rDNA PCR,esophageal ...AIM: To identify the bacterial flora in conditions such as Barrett's esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora.METHODS: Using broad-range 16S rDNA PCR,esophageal biopsies were examined from 24 patients [9with normal esophageal mucosa, 12 with gastroesophageal reflux disease (GERD), and 3 with Barrett's esophagus].Two separate broad-range PCR reactions were performed for each patient, and the resulting products were cloned.In one patient with Barrett's esophagus, g9 PCR clones were analyzed.RESULTS: Two separate clones were recovered from each patient (total = 48), representing 24 different species, with 14 species homologous to known bacteria,5 homologous to unidentified bacteria, and 5 were not homologous (<97% identity) to any known bacterial 16S rDNA sequences. Seventeen species were found in the reflux esophagitis patients, 5 in the Barrett's esophagus patients, and 10 in normal esophagus patients.Further analysis concentrating on a single biopsy from an individual with Barrett's esophagus revealed the presence of 21. distinct bacterial species. Members of four phyla were represented, including Bacteroidetes,Firmicutes, Proteobacteria, and Actinobacteria.Microscopic examination of each biopsy demonstrated bacteria in intimate association with the distal esophageal epithelium, suggesting that the presence of these bacteria is not transitory.CONCLUSION: These findings provide evidence for a complex, residential bacterial population in esophageal reflux-related disorders. While much of this biota is present in the normal esophagus, more detailed comparisons may help identify potential disease associations.展开更多
Enterolithiasis or formation of gastrointestinal concretions is an uncommon medical condition that develops in the setting of intestinal stasis in the presence of the intestinal diverticula,surgical enteroanastomoses,...Enterolithiasis or formation of gastrointestinal concretions is an uncommon medical condition that develops in the setting of intestinal stasis in the presence of the intestinal diverticula,surgical enteroanastomoses,blind pouches,afferent loops,incarcerated hernias,small intestinal tumors,intestinal kinking from intra-abdominal adhesions,and stenosing or stricturing Crohn’s disease and intestinal tuberculosis.Enterolithiasis is classified into primary and secondary types.Its prevalence ranges from 0.3%to 10%in selected populations.Proximal primary enteroliths are composed of choleic acid salts and distal enteroliths are calcified.Clinical presentation includes abdominal pains,distention,nausea,and vomiting of occasionally sudden but often fluctuating subacute nature which occurs as a result of the enterolith tumbling through the bowel lumen.Thorough history and physical exam coupled with radiologic imaging helps establish a diagnosis in a patient at risk.Complications include bowel obstruction,direct pressure injury to the intestinal mucosa,intestinal gangrene,intussusceptions,afferent loop syndrome,diverticulitis,iron deficiency anemia,gastrointestinal hemorrhage,and perforation.Mortality of primary enterolithiasis may reach 3%and secondary enterolithiasis 8%.Risk factors include poorly conditioned patients with significant obstruction and delay in diagnosis.Treatment relies on timely recognition of the disease and endoscopic or surgical intervention.With advents in new technology,improved outcome is expected for patients with enterolithiasis.展开更多
BACKGROUND System based practice(SBP) milestones require trainees to effectively navigate the larger health care system for optimal patient care. In gastroenterology training programs, the assessment of SBP is difficu...BACKGROUND System based practice(SBP) milestones require trainees to effectively navigate the larger health care system for optimal patient care. In gastroenterology training programs, the assessment of SBP is difficult due to high volume, high acuity inpatient care, as well as inconsistent direct supervision. Nevertheless,structured assessment is required for training programs. We hypothesized that objective structured clinical examination(OSCE) would be an effective tool for assessment of SBP.AIM To develop a novel method for SBP milestone assessment of gastroenterology fellows using the OSCE.METHODS For this observational study, we created 4 OSCE stations: Counseling an impaired colleague, handoff after overnight call, a feeding tube placement discussion, and giving feedback to a medical student on a progress note. Twentysix first year fellows from 7 programs participated. All fellows encountered identical case presentations. Checklists were completed by trained standardized patients who interacted with each fellow participant. A report with individual and composite scores was generated and forwarded to program directors to utilize in formative assessment. Fellows also received immediate feedback from a faculty observer and completed a post-session program evaluation survey.RESULTS Survey response rate was 100%. The average composite score across SBP milestones for all cases were 6.22(SBP1), 4.34(SBP2), 3.35(SBP3), and 6.42(SBP4)out of 9. The lowest composite score was in SBP 3, which asks fellows to advocate for cost effective care. This highest score was in patient care 2, which asks fellows to develop comprehensive management plans. Discrepancies were identified between the fellows’ perceived performance in their self-assessments and Standardized Patient checklist evaluations for each case. Eighty-seven percent of fellows agreed that OSCEs are an important component of their clinical training,and 83% stated that the cases were similar to actual clinical encounters. All participating fellows stated that the immediate feedback was "very useful." One hundred percent of the fellows stated they would incorporate OSCE learning into their clinical practice.CONCLUSION OSCEs may be used for standardized evaluation of SBP milestones. Trainees scored lower on SBP milestones than other more concrete milestones. Training programs should consider OSCEs for assessment of SBP.展开更多
We investigate several robust preconditioners for solving the saddle-point linear systems that arise from spatial discretization of unsteady and steady variablecoefficient Stokes equations on a uniform staggered grid....We investigate several robust preconditioners for solving the saddle-point linear systems that arise from spatial discretization of unsteady and steady variablecoefficient Stokes equations on a uniform staggered grid.Building on the success of using the classical projection method as a preconditioner for the coupled velocitypressure system[B.E.Griffith,J.Comp.Phys.,228(2009),pp.7565–7595],as well as established techniques for steady and unsteady Stokes flow in the finite-element literature,we construct preconditioners that employ independent generalized Helmholtz and Poisson solvers for the velocity and pressure subproblems.We demonstrate that only a single cycle of a standard geometric multigrid algorithm serves as an effective inexact solver for each of these subproblems.Contrary to traditional wisdom,we find that the Stokes problem can be solved nearly as efficiently as the independent pressure and velocity subproblems,making the overall cost of solving the Stokes system comparable to the cost of classical projection or fractional step methods for incompressible flow,even for steady flow and in the presence of large density and viscosity contrasts.Two of the five preconditioners considered here are found to be robust to GMRES restarts and to increasing problem size,making them suitable for large-scale problems.Our work opens many possibilities for constructing novel unsplit temporal integrators for finite-volume spatial discretizations of the equations of low Mach and incompressible flow dynamics.展开更多
基金Supported by(in part)Grants UH2CA140233 from the Human Microbiome Project of the NIH Roadmap Initiative and National Cancer InstituteR01AI063477 from the National Institute of Allergy and Infectious Diseases+1 种基金DE-11443 from the National Institute of Dental and Craniofacial ResearchU19DE018385 from the National Institute of Dental & Craniofacial Research
文摘AIM:To design and validate broad-range 16S rRNA primers for use in high throughput sequencing to classify bacteria isolated from the human foregut microbiome.METHODS:A foregut microbiome dataset was constructed using 16S rRNA gene sequences obtained from oral,esophageal,and gastric microbiomes produced by Sanger sequencing in previous studies represented by 219 bacterial species.Candidate primers evaluated were from the European rRNA database.To assess the effect of sequence length on accuracy of classification,16S rRNA genes of various lengths were created by trimming the full length sequences.Sequences spanning various hypervariable regions were selected to simulate the amplicons that would be obtained using possible primer pairs.The sequences were compared with full length 16S rRNA genes for accuracy in taxonomic classification using online software at the Ribosomal Database Project (RDP).The universality of the primer set was evaluated using the RDP 16S rRNA database which is comprised of 433 306 16S rRNA genes,represented by 36 phyla.RESULTS:Truncation to 100 nucleotides(nt)downstream from the position corresponding to base 28 in the Escherichia coli 16S rRNA gene caused misclassification of 87(39.7%)of the 219 sequences,compared with misclassification of only 29(13.2%)sequences with truncation to 350 nt.Among 350-nt sequence reads within various regions of the 16S rRNA gene,the reverse read of an amplicon generated using the 343F/798R primers had the least(8.2%)effect on classification.In comparison,truncation to 900 nt mimicking single pass Sanger reads misclassified 5.0%of the 219 sequences.The 343F/798R amplicon accurately assigned 91.8%of the 219 sequences at the species level.Weighted by abundance of the species in the esophageal dataset,the 343F/798R amplicon yielded similar classification accuracy without a significant loss in species coverage(92%).Modification of the 343F/798R primers to 347F/803R increased their universality among foregut species.Assuming that a typicalpolymerase chain reaction can tolerate 2 mismatches between a primer and a template,the modified 347F and 803R primers should be able to anneal 98%and 99.6%of all 16S rRNA genes in the RDP database.CONCLUSION:347F/803R is the most suitable pair of primers for classification of foregut 16S rRNA genes but also possess universality suitable for analyses of other complex microbiomes.
文摘Gastroesophageal reflux disease(GERD) is a frequently encountered disorder. Obesity is an important risk factor for GERD, and there are several pathophysiologic mechanisms linking the two conditions. For obese patients with GERD, much of the treatment effort is focused on weight loss and its consistent benefit to symptoms, while there is a relative lack of evidence regarding outcomes after novel or even standard medical therapy is offered to this population. Physicians are hesitant to recommend operative anti-reflux therapy to obese patients due to the potentially higher risks and decreased efficacy, and these patients instead are often considered for bariatric surgery. Bariatric surgical approaches are broadening, and each technique has emerging evidence regarding its effect on both the risk and outcome of GERD. Furthermore, combined antireflux and bariatric options are now being offered to obese patients with GERD. However, currently Rouxen-Y gastric bypass remains the most effective surgical treatment option in this population, due to its consistent benefits in both weight loss and GERD itself. This article aims to review the impact of both conservative and aggressive approaches of obesity treatment on GERD.
文摘The prevalence of type 2 diabetes is rising worldwide, especially in older adults. Diet and lifestyle, particularly plant-based diets, are ef-fective tools for type 2 diabetes prevention and management. Plant-based diets are eating patterns that emphasize legumes, whole grains,vegetables, fruits, nuts, and seeds and discourage most or all animal products. Cohort studies strongly support the role of plant-based diets,and food and nutrient components of plant-based diets, in reducing the risk of type 2 diabetes. Evidence from observational and interven-tional studies demonstrates the benefits of plant-based diets in treating type 2 diabetes and reducing key diabetes-related macrovascular andmicrovascular complications. Optimal macronutrient ratios for preventing and treating type 2 diabetes are controversial; the focus should insteadbe on eating patterns and actual foods. However, the evidence does suggest that the type and source of carbohydrate （unrefined versus refined）,fats （monounsaturated and polyunsaturated versus saturated and trans）, and protein （plant versus animal） play a major role in the prevention andmanagement of type 2 diabetes. Multiple potential mechanisms underlie the benefits of a plant-based diet in ameliorating insulin resistance, in-cluding promotion of a healthy body weight, increases in fiber and phytonutrients, food-microbiome interactions, and decreases in saturated fat,advanced glycation endproducts, nitrosamines, and heme iron.
基金Supported by The Intramural Research Programs of the National Institutes of Health Clinical Center and the National Institute of Allergy and Infectious Diseases
文摘Vanishing bile duct syndrome(VBDS) is a group of rare disorders characterized by ductopenia,the progressive destruction and disappearance of intrahepatic bile ducts leading to cholestasis.Described in association with medications,autoimmune disorders,cancer,transplantation,and infections,the specific mechanisms of disease are not known.To date,only 4 cases of VBDS have been reported in human immunodeficiency virus(HIV) infected patients.We report 2 additional cases of HIV-associated VBDS and review the features common to the HIV-associated cases.Presentation includes hyperbilirubinemia,normal liver imaging,and negative viral and autoimmune hepatitis studies.In HIV-infected subjects,VBDS occurred at a range of CD4+ T-cell counts,in some cases following initiation or change in antiretroviral therapy.Lymphoma was associated with two cases;nevirapine,antibiotics,and viral co-infection were suggested as etiologies in the other cases.In HIV-positive patients with progressive cholestasis,early identification of VBDS and referral for transplantation may improve outcomes.
基金Supported by Grant from the National Institutes of Health (Tchou-Wong), No. ES-000260 and No. AI-059476
文摘AIM: To investigate the therapeutic potential of an RNA ligand (aptamer) specific for the catalytic ricin A-chain (RTA), the protective effects of a 31-nucleo-tide RNA aptamer (31RA), which formed a high affi nity complex with RTA, against ricin-induced toxicity in cellbased luciferase translation and cell cytotoxicity assays were evaluated. METHODS: To test the therapeutic potential of anti-RTA aptamers in Chinese hamster ovary (CHO) AA8 cells stably transfected with a tetracycline regulat-able promoter, ricin ribotoxicity was measured using luciferase and ricin-induced cytotoxicity was ascertained by MTS cell proliferation assay with tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium]. RESULTS: Inhibition of protein synthesis by ricin in CHO AA8 cells resulted in diminished luciferase activity and treatment with polyclonal antibody against degly-cosylated RTA (dgA) neutralized the inhibitory effects of ricin on luciferase activity and protected against ricin-induced cytotoxicity as measured by MTS assay. The 31RA anti-RTA aptamer inhibited the translation of luciferase mRNA in cell-free reticulocyte translation as- say. 31RA aptamer also partially neutralized the inhibitory effects of ricin on luciferase activity and partially protected against ricin-induced cytotoxicity in CHO AA8 cells. CONCLUSION: We have shown that anti-RTA RNA aptamer can protect against ricin ribotoxicity in cellbased luciferase and cell cytotoxicity assays. Hence, RNA aptamer that inhibits RTA enzymatic activity represents a novel class of nucleic acid inhibitor that has the potential to be developed as a therapeutic agent for the treatment of ricin intoxication.
基金Supported by Department of Pathology Research Fund,NYU School of Medicine,New York,NY 10016,United States
文摘AIM:To determine the expression and clinical significance of transcriptional intermediary factor 1 gamma (TIF1γ),Smad4 and transforming growth factor-beta (TGFβR) across a spectrum representing colorectal cancer (CRC) development.METHODS:Tissue microarrays were prepared from archival paraffin embedded tissue,including 51 colorectal carcinomas,25 tubular adenomas (TA) and 26 HPs,each with matched normal colonic epithelium.Immunohistochemistry was performed using antibodies against TIF1γ,Smad4 and TGFβ RⅡ.The levels of expression were scored semi-quantitatively (score 0-3 or loss and retention for Smad4).RESULTS:Overexpression of TIF1γ was detected in 5/26 (19%) HP;however,it was seen in a significantly higher proportion of neoplasms,15/25 (60%) TAs and 24/51 (47%) CRCs (P<0.05).Normal colonic mucosa,HP,and TAs showed strong Smad4 expression,while its expression was absent in 22/51 (43%) CRCs.Over-expression of TGFβ RⅡ was more commonly seen in neoplasms,13/25 (52%) TAs and 29/51 (57%) CRCs compared to 9/26 (35%) HP (P<0.05).Furthermore,there was a correlation between TIF1γ overexpression and Smad4 loss in CRC (Kendall tau rank correlation value=0.35,P<0.05).The levels of TIF1γ overexpression were significantly higher in stage Ⅲ than in stage Ⅰ and Ⅱ CRC (P<0.05).CONCLUSION:The findings suggest that over-expression of TIF1γ occurs in early stages of colorectal carcinogenesis,is inversely related with Smad4 loss,and may be a prognostic indicator for poor outcome.
基金Supported by NIEHS Center Grant ES00260(Tchou-Wong KM)NIAID R21 Grant AI059476(Tchou-Wong KM)from the National Institutes of Health
文摘AIM:To evaluate the ability of anti-ricin A-chain antibodies,delivered intracellularly,to protect against ricininduced cytotoxicity in RAW264.7 cells. METHODS:Anti-deglycosylated ricin A-chain antibody and RAC18 anti-ricin A-chain monoclonal antibody were delivered intracellularly by encapsulating in liposomes or via conjugation with the cell-penetrating MTS-transport peptide.RAW264.7 cells were incubatedwith these antibodies either before or after ricin exposure.The changes in cytotoxicity were estimated by MTT assay.Co-localization of internalized antibody and ricin was evaluated by fluorescence microscopy. RESULTS:Internalized antibodies significantly increased cell viability either before or after ricin exposure compared to the unconjugated antibodies.Fluorescence microscopy confirmed the co-localization of internalized antibodies and ricin inside the cells. CONCLUSION:Intracellular delivery of antibodies to neutralize the ricin toxin after cellular uptake supports the potential use of cell-permeable antibodies for postexposure treatment of ricin intoxication.
文摘Continuous-flow left ventricular assist devices(CF-LVADs)have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or,more recently,as destination therapy.However,its implantations carries a risk of complications including infection,device malfunction,arrhythmias,right ventricular failure,thromboembolic disease,postoperative and nonsurgical bleeding.A significant number of left ventricular assist devices(LVAD)recipients may experience recurrent gastrointestinal hemorrhage,mainly due to combination of antiplatelet and vitamin K antagonist therapy,activation of fibrinolytic pathway,acquired von Willebrand factor deficiency,and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump.Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions,extended hospital stays,multiple readmissions,and overall mortality.Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients,addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion.Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.
文摘Primary adult hypertrophic pyloric stenosis is a rare but important cause of gastric outlet obstruction that may be misdiagnosed as idiopathic gastroparesis.Clinically,patients present with early satiety,abdominal fullness,nausea,epigastric discomfort and eructation.Permanent gastric retention of a video capsule endoscope is diagnostic in differentiating between the two diseases,in the absence of an organic gastric outlet obstruction.This case presents the longest video capsule retention in the medical literature to date.It is also the first case report of adult hypertrophic pyloric stenosis diagnosed with video capsule endoscopy or a computed tomography scan.Finally,an unusual"plugging"of the gastric outlet with free floating capsule has an augmented effect on disease physiology and on patient’s symptoms.
基金Supported by R01CA97946, R21DK57941, R01GM63270,R01 DK58587, and R01CA77955, and by the General Clinical Research Center core grant to New York University School of Medicine (NIH/NCRR M01 RR00096) from the National Institutes of Health, by the Medical Research Service of the Department of Veterans Affairs, and by the Ellison Medical Foundation
文摘AIM: To identify the bacterial flora in conditions such as Barrett's esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora.METHODS: Using broad-range 16S rDNA PCR,esophageal biopsies were examined from 24 patients [9with normal esophageal mucosa, 12 with gastroesophageal reflux disease (GERD), and 3 with Barrett's esophagus].Two separate broad-range PCR reactions were performed for each patient, and the resulting products were cloned.In one patient with Barrett's esophagus, g9 PCR clones were analyzed.RESULTS: Two separate clones were recovered from each patient (total = 48), representing 24 different species, with 14 species homologous to known bacteria,5 homologous to unidentified bacteria, and 5 were not homologous (<97% identity) to any known bacterial 16S rDNA sequences. Seventeen species were found in the reflux esophagitis patients, 5 in the Barrett's esophagus patients, and 10 in normal esophagus patients.Further analysis concentrating on a single biopsy from an individual with Barrett's esophagus revealed the presence of 21. distinct bacterial species. Members of four phyla were represented, including Bacteroidetes,Firmicutes, Proteobacteria, and Actinobacteria.Microscopic examination of each biopsy demonstrated bacteria in intimate association with the distal esophageal epithelium, suggesting that the presence of these bacteria is not transitory.CONCLUSION: These findings provide evidence for a complex, residential bacterial population in esophageal reflux-related disorders. While much of this biota is present in the normal esophagus, more detailed comparisons may help identify potential disease associations.
文摘Enterolithiasis or formation of gastrointestinal concretions is an uncommon medical condition that develops in the setting of intestinal stasis in the presence of the intestinal diverticula,surgical enteroanastomoses,blind pouches,afferent loops,incarcerated hernias,small intestinal tumors,intestinal kinking from intra-abdominal adhesions,and stenosing or stricturing Crohn’s disease and intestinal tuberculosis.Enterolithiasis is classified into primary and secondary types.Its prevalence ranges from 0.3%to 10%in selected populations.Proximal primary enteroliths are composed of choleic acid salts and distal enteroliths are calcified.Clinical presentation includes abdominal pains,distention,nausea,and vomiting of occasionally sudden but often fluctuating subacute nature which occurs as a result of the enterolith tumbling through the bowel lumen.Thorough history and physical exam coupled with radiologic imaging helps establish a diagnosis in a patient at risk.Complications include bowel obstruction,direct pressure injury to the intestinal mucosa,intestinal gangrene,intussusceptions,afferent loop syndrome,diverticulitis,iron deficiency anemia,gastrointestinal hemorrhage,and perforation.Mortality of primary enterolithiasis may reach 3%and secondary enterolithiasis 8%.Risk factors include poorly conditioned patients with significant obstruction and delay in diagnosis.Treatment relies on timely recognition of the disease and endoscopic or surgical intervention.With advents in new technology,improved outcome is expected for patients with enterolithiasis.
文摘BACKGROUND System based practice(SBP) milestones require trainees to effectively navigate the larger health care system for optimal patient care. In gastroenterology training programs, the assessment of SBP is difficult due to high volume, high acuity inpatient care, as well as inconsistent direct supervision. Nevertheless,structured assessment is required for training programs. We hypothesized that objective structured clinical examination(OSCE) would be an effective tool for assessment of SBP.AIM To develop a novel method for SBP milestone assessment of gastroenterology fellows using the OSCE.METHODS For this observational study, we created 4 OSCE stations: Counseling an impaired colleague, handoff after overnight call, a feeding tube placement discussion, and giving feedback to a medical student on a progress note. Twentysix first year fellows from 7 programs participated. All fellows encountered identical case presentations. Checklists were completed by trained standardized patients who interacted with each fellow participant. A report with individual and composite scores was generated and forwarded to program directors to utilize in formative assessment. Fellows also received immediate feedback from a faculty observer and completed a post-session program evaluation survey.RESULTS Survey response rate was 100%. The average composite score across SBP milestones for all cases were 6.22(SBP1), 4.34(SBP2), 3.35(SBP3), and 6.42(SBP4)out of 9. The lowest composite score was in SBP 3, which asks fellows to advocate for cost effective care. This highest score was in patient care 2, which asks fellows to develop comprehensive management plans. Discrepancies were identified between the fellows’ perceived performance in their self-assessments and Standardized Patient checklist evaluations for each case. Eighty-seven percent of fellows agreed that OSCEs are an important component of their clinical training,and 83% stated that the cases were similar to actual clinical encounters. All participating fellows stated that the immediate feedback was "very useful." One hundred percent of the fellows stated they would incorporate OSCE learning into their clinical practice.CONCLUSION OSCEs may be used for standardized evaluation of SBP milestones. Trainees scored lower on SBP milestones than other more concrete milestones. Training programs should consider OSCEs for assessment of SBP.
文摘We investigate several robust preconditioners for solving the saddle-point linear systems that arise from spatial discretization of unsteady and steady variablecoefficient Stokes equations on a uniform staggered grid.Building on the success of using the classical projection method as a preconditioner for the coupled velocitypressure system[B.E.Griffith,J.Comp.Phys.,228(2009),pp.7565–7595],as well as established techniques for steady and unsteady Stokes flow in the finite-element literature,we construct preconditioners that employ independent generalized Helmholtz and Poisson solvers for the velocity and pressure subproblems.We demonstrate that only a single cycle of a standard geometric multigrid algorithm serves as an effective inexact solver for each of these subproblems.Contrary to traditional wisdom,we find that the Stokes problem can be solved nearly as efficiently as the independent pressure and velocity subproblems,making the overall cost of solving the Stokes system comparable to the cost of classical projection or fractional step methods for incompressible flow,even for steady flow and in the presence of large density and viscosity contrasts.Two of the five preconditioners considered here are found to be robust to GMRES restarts and to increasing problem size,making them suitable for large-scale problems.Our work opens many possibilities for constructing novel unsplit temporal integrators for finite-volume spatial discretizations of the equations of low Mach and incompressible flow dynamics.
