Perception from students regarding online synchronous interactive teaching in the clinical year during COVID-19 pandemic.

AIM: The global pandemic of COVID-19 has led to extensive practice of online learning. Our main objective is to compare different online synchronous interactive learning activities to evaluate students' perceptions. Moreover, we also aim to identify factors influencing their perceptions in these classes. METHODS: A cross-sectional, questionnaire-based study focusing on clinical year medical students' perceptions and feedback was conducted between February 2021 -June 2021 at the University of Hong Kong. Online learning activities were divided into bedside teaching, practical skill session, problem-based learning (PBL) or tutorial, and lecture. A questionnaire based on the Dundee Ready Education Environment Measure (DREEM) was distributed to 716 clinical year students to document their perceptions. RESULTS: One hundred responses were received with a response rate of 15.4% (110/716, including 96 from bedside teaching, 67 from practical skill session, 104 from PBL/tutorial, and 101 from lecture). For the mean score of the DREEM-extracted questionnaire, online PBL/tutorial scored the highest (2.72 ± 0.54), while bedside scored the lowest (2.38 ± 0.68, p = 0.001). Meanwhile, there was no significant difference when we compared different school years (p = 0.39), age (p = 0.37), gender (p = 1.00), year of internet experience (<17 vs ≥17 years p = 0.59), or prior online class experience (p = 0.62). When asked about students' preference for online vs face-to-face classes. Students showed higher preferences for online PBL/tutorial (2.06 ± 0.75) and lectures (2.27 ± 0.81). Distraction remains a significant problem across all four learning activities. A multivariate analysis was performed regarding students' reported behavior in comparison with their perception through the DREEM-extracted questionnaire. The results showed that good audio and video quality had a significant and positive correlation with their perception of online bedside teaching, practical skill sessions, and PBL/tutorial. It also showed that the use of the video camera correlated with an increase in perception scores for lectures. CONCLUSION: The present analysis has demonstrated that students' perception of different online synchronous interactive learning activities varies. Further investigations are required on minimizing distraction during online classes.

Distance education for anatomy and surgical training - A systematic review.

Rapid development of COVID-19 has resulted in a massive shift from traditional to online teaching. This review aims to evaluate the effectiveness of distance learning on anatomy and surgical training. This systematic review was conducted in line with the PRISMA statement and current methodological literature. The databases CINAHL, Cochrane, EMBASE and Pubmed were searched using the search terms "Distant learning" OR "Distance learning" AND "Anatomy OR Surgery". 182 non-duplicate studies were identified. 20 studies were included for qualitative analysis. 10 studies evaluated students' performance with distance learning. 3 studies suggested that students' learning motivation improved with distance learning pedagogy. 5 studies found improved student performance with distance learning (performance or task completion time) when compared to conventional physical method. While 2 other studies found non-inferior student performance. 10 studies evaluated students' feedback on distance learning. Most feedbacks were positive, with flexibility, efficiency, increased motivation and better viewing angles as the most-liked features of distance teaching. 4 studies pointed out some limitations of distance learning, including the lack of personal contact with tutor, poor network and reduced student concentration. 7 studies evaluated tutors' feedback on distance learning. Tutors generally liked online platforms for the ease of tracking silent students, monitoring performance and updating fast-changing knowledge. Yet the lack of hands-on experience for students, technical issues and high costs are the main concerns for tutors. In conclusion, distance learning is a feasible alternative for anatomy and surgical teaching.

Online teaching of basic surgical skills to medical students during the COVID-19 pandemic: a case-control study.

PURPOSE: Medical education has been disrupted by the COVID-19 pandemic in many countries, with face-to-face lectures replaced by pre-recorded videos. However, surgical skills training cannot be replaced easily by videos, as a high level of tutor-student interaction is required. Thus, we developed a new web-based surgical skill learning session (WSSL). This case-control study evaluates the surgical skills competency of medical students taught by the WSSL. METHODS: This case-control study compares WSSL with face-to-face tutorials. Students were assigned randomly to one of two groups according to the teaching method. Independent blinded assessment was performed by a standardized marking scheme, modified from the Objective Structured Assessment of Technical Skills (OSATS) global rating scale. RESULTS: We recruited 62 final-year medical students into the study, with 33 randomized to the face-to-face teaching group (control group), and 29 to the WSSL group(case group) according to their student number. The baseline demographic characteristics of the two groups were comparable. The mean score at the clinical competency assessment of the control group was 4.8/5 (range 4-5) and that of the case group was 4.7/5 (range 4-5) (p = 1). There were no difficulties with program or hardware installation reported by the WSSL students. CONCLUSIONS: Surgical skills performance was comparable between students who were taught by the WSSL and those taught by conventional face-to-face tutorials.

A comparative study regarding distance learning and the conventional face-to-face approach conducted problem-based learning tutorial during the COVID-19 pandemic.

BACKGROUND: Educational pedagogies were modified during the COVID-19 pandemic to minimise interruption to teaching. One approach has been the distance learning problem-based learning (PBL) tutorial utilising the online peer-to-peer platform. The aim of this study was to compare the performance of students using distance learning PBL tutorials using with that of students utilising the conventional face-to-face approach. METHODS: This retrospective study was conducted in a single academic institution. We compared two groups of fourth-year medical students from the same class: one group used distance learning (DL); the other, the face-to-face (FF) method. We used students' baseline performance at the preceding block for one-to-one propensity score matching. Students utilising the PBL tutorial were given grades by their tutors according to a standardised scoring system encompassing five key areas (score range: 0-10). The main outcome was a student's total score (i.e., the sum of the scores from the five key areas, ranging from 0 to 50). RESULT: We matched 62 students in each group. With four tutorials, there were 490 observations, with 245 in each group. The mean total score for the DL group was 37.5 ± 4.6, which was significantly lower than that of the FF group (39.0 ± 4.4, p < 0.001). We noted that students in the DL group had a significantly lower scores for all five areas of proficiency: participation, communication, preparation, critical thinking and group skills. CONCLUSION: Findings of this study revealed that the performance of students utilising the DL PBL tutorials was lower than that of students participating in the conventional FF approach. Further studies are needed to ascertain the underlying cause.

Exosomal miRNAs as circulating biomarkers for prediction of development of haematogenous metastasis after surgery for stage II/III gastric cancer.

Exosomes secreted by living cancer cells can regulate metastasis. Exosomal miRNAs can reflect pathological conditions of the original cancer cells. Therefore, we aim to identify exosomal miRNAs as circulating biomarkers for haematogenous metastasis of gastric cancer. Pre-treatment serum samples of eighty-nine patients with stage II/III gastric cancer were collected. Thirty-four of them developed haematogenous metastasis after surgery and the other fifty-five did not. Extraction of exosomes was validated by western blot, transmission electron microscopy and nanoparticle tracking analysis. MiRNA qPCR array was performed in three matched pairs of samples. Internal control was selected from PCR array and validated in the remaining samples. Expressions of exosomal miRNAs were evaluated in the remaining samples by RT-qPCR, as well as in gastric cancer tissue samples and cell culture medium. Expression levels of exosomal miRNAs were analysed with clinical characteristics. The results indicated thirteen up-regulated and six down-regulated miRNAs were found after normalization. MiR-379-5p and miR-410-3p were significantly up-regulated in metastatic patients (P < .01). Higher expression of exosomal miR-379-5p or miR-410-3p showed shorter progression-free survival of the patients (P < .05). It was also found that miR-379-5p and miR-410-3p were down-regulated in gastric cancer tissue samples, while they were significantly up-regulated in gastric cancer cell culture medium compared with cancer cells. In conclusion, exosomal miRNAs are promising circulating biomarkers for prediction of development of haematogenous metastasis after surgery for stage II/III gastric cancer.

α-Actinin-4 promotes metastasis in gastric cancer.

Metastasis increases the mortality rate of gastric cancer, which is the third leading cause of cancer-associated deaths worldwide. This study aims to identify the genes promoting metastasis of gastric cancer (GC). A human cell motility PCR array was used to analyze a pair of tumor and non-tumor tissue samples from a patient with stage IV GC (T3N3M1). Expression of the dysregulated genes was then evaluated in GC tissue samples (n=10) and cell lines (n=6) via qPCR. Expression of α-actinin-4 (ACTN4) was validated in a larger sample size (n=47) by qPCR, western blot and immunohistochemistry. Knockdown of ACTN4 with specific siRNAs was performed in GC cells, and adhesion assays, transwell invasion assays and migration assays were used to evaluate the function of these cells. Expression of potential targets of ACTN4 were then evaluated by qPCR. Thirty upregulated genes (greater than twofold) were revealed by the PCR array. We focused on ACTN4 because it was upregulated in 6 out of 10 pairs of tissue samples and 5 out of 6 GC cell lines. Further study indicated that ACTN4 was upregulated in 22/32 pairs of tissue samples at stage III &IV (P=0.0069). Knockdown of ACTN4 in GC cells showed no significant effect on cell proliferation, but significantly increased cell-matrix adhesion, as well as reduced migration and invasion of AGS, MKN7 and NCI-N87 cells. We found that NF-κB was downregulated in GC with the knockdown of ACTN4. In conclusion, this is the first study to indicate that ACTN4 is significantly upregulated in patients with metastatic GC. ACTN4 reduces cell adhesion and enhances migration and invasion of GC cells and may therefore be a novel therapeutic target for GC.

Plasma miR-940 may serve as a novel biomarker for gastric cancer.

It was reported that circulating microRNAs could be applied as non-invasive biomarkers for cancer monitoring. The purpose of this study was to identify plasma miRNA that may serve as a novel biomarker for gastric cancer and to evaluate its clinical application. MicroRNA profiles were generated from plasma samples of 5 patients with gastric cancer (GC) versus 5 healthy controls (HC). MicroRNA-940 (miR-940) was one of the most downregulated miRNAs with fold change of 0.164. It was revealed that the expression of miR-940 was downregulated in both the initial set (N = 30, P < 0.0001) and the validation set (N = 80, P < 0.0001) of plasma samples of patients with gastric cancer. The sensitivity was obviously higher than the current biomarkers CEA and CA19-9 (81.25 % vs. 22.54 % and 15.71 %). MiR-940 was also significantly downregulated in gastric cancer tissue samples (N = 34, P = 0.0015), as well as in cancer cell lines (N = 7). Importantly, miR-940 was significantly highly expressed in stomach tissue samples than in other types of tissue samples including the liver, breast, thyroid, and lung. Moreover, there was a trend of lower expression of miR-940 from early to advanced stage of gastric cancer. Target prediction suggested that miR-940 regulated cell signaling including NF-κB and Wnt/ß-catenin, as well as pathways of cell communication and adhesion. These pathways play critical roles in gastric cancer initiation and progression. It is the first report that miR-940 may mainly express in the stomach. Downregulation of plasma miR-940 may serve as a novel biomarker for detection of gastric cancer.

A three-miRNA signature as promising non-invasive diagnostic marker for gastric cancer.

BACKGROUND: Despite the declining incidence of gastric cancer, mortality rate remains high due to late presentation. We aimed to evaluate the sensitivity of miRNA as a diagnostic marker for gastric cancer in the circulation. METHODS: Plasma samples from 3 independent groups comprise 123 gastric cancer patients and 111 healthy controls for miRNA profiling from microarray screening. RESULTS: Microarray data showed that 25 miRNAs were upregulated in gastric cancer patients and 6 highly expressed miRNAs (miR-18a, miR-140-5p, miR-199a-3p, miR-627, miR-629 and miR-652) were selected for validation. In an independent validation set, levels of miR-627, miR-629 and miR-652 were significantly higher in gastric cancer patients than healthy controls (P <0.0001). An algorithm with improved sensitivity and specificity as gastric cancer classifier was adopted and validated in another random set of 15 plasma samples. Results showed that combination of 3 miRNAs obtained the highest area under curve, with a cut-off at 0.373, with a sensitivity of 86.7% and a specificity of 85.5%. CONCLUSION: This study revealed a three-miRNA signature as a promising classifier for gastric cancer, and greatly enhances the feasibility of circulating miRNAs as non-invasive diagnostic marker for this disease.

Treatment of Gastric Metaplasia or Dysplasia by Endoscopic Radiofrequency Ablation: A Pilot Study.

BACKGROUND/AIMS: Patients with gastric intestinal metaplasia and dysplasia are at increased risk of gastric cancer development. We tested the feasibility of using endoscopic radiofrequency ablation for the treatment of dysplasia and metaplasia in the stomach. METHODOLOGY: Patients who had histologically confirmed low-grade gastric dysplasia or IM were recruited. Endoscopic RFA was performed at 8 week-intervals for a maximum of 3 sessions. All patients were followed up by endoscopy until 12 months post-RFA. The primary outcome was the complete eradication of dysplasia or IM on follow-up. Secondary outcome was adverse events related to RFA. RESULTS: A total of 12 patients were recruited. Four patients had low-grade dysplasia and the remaining 8 patients had non-dysplastic IM at baseline. At one year after RFA, complete eradication of dysplasia was noted in four patients with low-grade dysplasia (100%). Gastric IM persisted in all patients with baseline metaplasia but the severity of IM improved in 6 (75%) patients. Endoscopic RFA was safe with minimal complications encountered. CONCLUSIONS: RFA successfully eradicated low-grade dysplasia of the stomach. Gastric IM however persisted after RFA but most patients had evidence of histological improvement on follow up.

MiR-410-3p suppresses primary gastric cancer and exosomes regulate endogenous expression of miR-410-3p.

MicroRNAs play significant roles in cancer initiation and progression. Exosomes are important extracellular vesicles for transporting molecules to distant sites. This study aims to investigate the functional roles of miR-410-3p in primary gastric cancer, as well as the roles of exosomes in regulating expression of miR-410-3p. In this study, forty-seven pairs of human gastric cancer tissue samples were collected. Endogenous expression of miR-410-3p in tissue samples and cell lines, and expression of exosomal miR-410-3p in cell culture medium were evaluated by RT-qPCR. Functional assays including cell proliferation assay by MTT, cell migration and invasion assay by transwell, and cell adhesion assay were performed. Targets of miR-410-3p were screened. Cell culture medium of culturing cell lines established from stomach (AGS and BCG23) was applied for culturing cell lines established from other sites (MKN45 and HEK293T). It was found that miR-410-3p was significantly downregulated in gastric cancer. Overexpression of miR-410-3p inhibited gastric cancer cell proliferation, migration, and invasion. MiR-410-3p mimic enhanced cell adhesion. HMGB1 was a target of miR-410-3p in primary gastric cancer. Expression of exosomal miR-410-3p in cell culture medium was dramatically higher than its endogenous expression. Exosomes from cell culture medium of AGS or BCG23 regulated endogenous expression of miR-410-3p in MKN45. In conclusion, miR-410-3p functioned as a tumor suppressor in primary gastric cancer. MiR-410-3p was higher expressed in exosomes of cell culture medium than its endogenous expression in cells. Endogenous expression of miR-410-3p in a distant site could be regulated by exosomes from the original site.

CD44 activation in mature B-cell malignancies by a novel recurrent IGH translocation.

Using inverse polymerase chain reaction, we identified CD44, located on chromosome 11p13, as a novel translocation partner of IGH in 9 of 114 cases of gastric, nongastric extranodal, follicular, and nodal diffuse large B-cell lymphoma (DLBCL). Notably, these translocations involving IGHSmu were detected in follicular lymphomas and exclusively in germinal center B cell-ike (GCB)-DLBCLs. CD44 is not expressed in reactive GC B cells. The IGHSmu/CD44 translocations substitute Smu for the CD44 promoter and remove exon 1 of CD44, resulting in the overexpression of Imu-CD44 hybrid mRNA transcripts activated from derivative 11 that encode a new CD44 variant lacking the leader peptide and with a unique C-terminus (CD44DeltaEx1). When overexpressed in vitro in the CD44(-) GCB-DLBCL cell line BJAB, CD44DeltaEx1-green fluorescent protein localized to the cytoplasm and nucleus, whereas CD44s-green fluorescent protein (standard form) localized to the plasma membrane. The ectopic expression of CD44DeltaEx1 in BJAB cells enhanced their proliferation rate and clonogenic ability, indicating a possible pathogenic role of the translocation.

A prospective case-control study on online teaching of ultrasonography skills to medical students during COVID-19 pandemic.

INTRODUCTION: A new Online interactive Ultrasound Teaching (OUT) was developed in our institution in March 2021 during COVID-19 outbreak. METHODS: This is a case control study on 65 final year medical students to compare OUT with conventional face-to-face ultrasound tutorials. There were 31 female and 34 male students. Median age was 23 years old (Range 21-30). Students were randomly assigned into two different teaching groups. Competency in conducting ultrasonic exam was assessed by Objective Structured Assessment of Ultrasound Skills (OSAUS). RESULTS: 32 students were randomized into the control group (face to face teaching) while 33 students were randomized into the case group (OUT). Baseline demographic characteristics were comparable between the two groups (p > 0.05).The median score of the blinded OSAUS assessment was 5.5 (Range 3-7). There were 4 (6.2%) students who failed in the assessment (scored <4 out of 7), and 10 (15.4%) students scored full marks in the assessment.The medians scores were 5.5 (Range 3-7), and 6 (Range 3-7) (p = 0.8057) in the control and case groups respectively. 6 (18.8%) students in the control group scored full mark, comparing to 4 (12.1%) students in the case group (p = 0.5105). 2 students from each group failed the assessment (p = 1). CONCLUSION: Ultrasonographic skills performance was comparable between students who were taught by OUT and conventional face-to-face tutorial.

Inhibition of EP2 receptor suppresses tumor growth and chemoresistance of gastric cancer.

Gastric cancer is one of the leading causes of cancer death in the world. Early diagnosis and effective chemotherapy are vital to reduce the overall mortality. Prostaglandin E2 (PGE2) has been implicated as an important factor in gastric cancer carcinogenesis. ECF based regimen (epirubicin, cisplatin, 5-fluorouracil) is the first-line chemotherapy for advanced gastric cancer. However, patients develop resistance after chemotherapy. The aim of this study is sought to investigate the role of EP2 receptor, a PGE2 receptor, and the antagonism of EP2 receptor in response to ECF treatment. Expression of EP2 receptor was evaluated in gastric cancer tissue samples and cell lines. Cell proliferation and cell apoptosis assays were performed in vitro and in vivo, upon knockdown of EP2 receptor, antagonist of EP2 receptor and/or ECF treatment. Western Blot was applied for evaluation of proteins relating to cell cycle, apoptosis and drug transporter. Next generation sequencing and ingenuity pathway analysis were applied for screening for downstream targets of EP2 receptor. Expressions of the targets of EP2 receptor were further evaluated in gastric cancer cells and tissues. In this study, we found that expression of EP2 receptor was significantly upregulated in gastric cancer. Inhibition of EP2 receptor reduced gastric cancer cell proliferation, induced cell cycle arrest proteins, and enhanced cell apoptosis. Moreover, knockdown of EP2 receptor by siRNA or antagonist sensitized gastric cancer cells to ECF. Silence of EP2 receptor also significantly abrogated gastric cancer growth in a mice model. Analysis revealed that CAV1 was a downstream target of EP2 receptor in gastric cancer. Our findings illustrated that blocking EP2 receptor reduced tumor growth and induced apoptosis in gastric cancer. This novel study unraveled CAV1 was a downstream target of EP2 receptor. Antagonizing EP2 receptor could be a potential therapeutic target in gastric cancer, in particular those with high EP2 receptor expression.

NF-κB targets miR-16 and miR-21 in gastric cancer: involvement of prostaglandin E receptors.

Cigarette smoke is one of the risk factors for gastric cancer and nicotine has been reported to promote tumor growth. Deregulation of microRNA (miRNA) and cyclooxygenase-2 (COX-2) expressions are hallmarks of many cancers including gastric cancer. Here, we used an miRNA array platform covering a panel of 95 human miRNAs to examine the expression profile in nicotine-treated gastric cancer cells. We found that miR-16 and miR-21 were upregulated upon nicotine stimulation, transfection with anti-miR-16 or anti-miR-21 significantly abrogated cell proliferation. In contrast, ectopic miR-16 or miR-21 expression exhibited a similar stimulatory effect on cell proliferation as nicotine. Nicotine-mediated IkappaBα degradation and nuclear factor-kappa B (NF-κB) translocation dose-dependently. Knockdown of NF-κB by short interfering RNA (siRNA) or specific inhibitor (Bay-11-7085) markedly suppressed nicotine-induced cell proliferation and upregulation of miR-16 and miR-21. Interestingly, NF-κB-binding sites were located in both miR-16 and miR-21 gene transcriptional elements and we showed that nicotine enhanced the binding of NF-κB to the promoters of miR-16 and miR-21. Furthermore, activation of COX-2/prostaglandin E2 (PGE2) signaling in response to nicotine was mediated by the action of prostaglandin E receptors (EP2 and EP4). EP2 or EP4 siRNA or antagonists impaired the nicotine-mediated NF-κB activity, upregulation of miR-16 and miR-21 and cell proliferation. Taken together, these results suggest that miR-16 and miR-21 are directly regulated by the transcription factor NF-κB and yet nicotine-promoted cell proliferation is mediated via EP2/4 receptors. Perhaps this study may shed light on the development of anticancer drugs to improve the chemosensitivity in smokers.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone promoted gastric cancer growth through prostaglandin E receptor (EP2 and EP4) in vivo and in vitro.

Prostaglandin E (EP) receptor is positively related with COX-2, which is involved in cancer biology. A mechanistic study on how 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) promotes gastric carcinogenesis is lacking. Recently, we found that nicotine promoted tumor growth through upregulation of the COX-2/prostaglandin E(2) pathway. This extended our study on the involvement of EP receptors in gastric carcinogenesis. Both in vitro and in vivo studies showed that NNK promoted cancer cell growth with concomitant EP2 and EP4 upregulation. We found that NNK stimulated vascular endothelial growth factor (VEGF) and angiogenesis, but suppressed apoptosis by increasing Bcl2 and decreasing caspase-3 expressions. Both EP2 and EP4 siRNA significantly impaired these tumorigenic actions of NNK in xenograft tumor. Cell cycle analysis showed that NNK increased S phase entry with increased cyclin D1 and the associated cyclin-dependent kinase 4/6, and downregulation of p21 and p27. The p38 phosphorylation was EP2/4-dependent, and SB203580 (p38 inhibitor) suppressed NNK-induced prostaglandin E(2) , VEGF, and cell proliferation. Antagonists of EP2 or EP4 abolished the elevated VEGF and VEGF receptor-2. These data strongly indicate that EP2/4 are important for NNK-promoted gastric carcinogenesis, thus providing a framework for future evaluation of EP antagonist(s) as anticancer drugs for smokers.

Distant surgical teaching during COVID-19 - A pilot study on final year medical students.

Introduction: Due to the COVID-19 outbreak, all on-site undergraduate medical teaching activities in Hong Kong have been suspended. A new web-based surgical skills learning (WSSL) for basic surgical skills training that were normally taught face-to-face was developed. Methodology: Basic surgical skills were taught with normal face-to-face tutorial to 30 final year medical students prior to the outbreak. The same group of students were invited to join the online WSSL using Zoom. Evaluation of WSSL was performed by a standardized questionnaire. Results: Thirty final year medical students (16 female, 14 male students) were recruited into the study. Median age was 23 (range 22-24). Most of them believed that WSSL is easy to follow. When compared to face-to-face teaching. Most students (N = 22, 73.4%) felt that WSSL was just as difficult/easy as conventional teaching for learning instrumental knots. Students were asked to evaluate WSSL by using a Likert scale of 1 to 10 (with 10 being highly recommended). Twelve (40%) students highly recommended WSSL (Score 9 to 10), 15 students (50%) slightly recommended WSSL (Score 6-8). Conclusion: Web-based surgical skills learning is a feasible alternative for face-to-face surgical skills teaching.

Anti-fibrotic effect of decorin in peritoneal dialysis and PD-associated peritonitis.

BACKGROUND: Progressive peritoneal fibrosis is a common complication in patients on long-term peritoneal dialysis (PD). PD-associated peritonitis is a major exacerbating factor. We investigated the anti-fibrotic properties of decorin secreted by peritoneal mesothelial cells. METHODS: Dialysate decorin level in stable PD patients and those with peritonitis was measured. In vitro experiments were conducted to investigate the effect of decorin in fibrotic response in human peritoneal mesothelial cells (HPMC). FINDINGS: Increasing PD duration was associated with a progressive decrease of dialysate decorin and CA125 levels. Dialysate decorin level correlated with CA125 level. Peritonitis episodes were associated with a massive drop of dialysate decorin, which persisted for over three months despite clinical recovery. Dialysate decorin level correlated with that of TGF-ß1, but was inversely related to IL-1ß and IL-8. TGF-ß1, IL-1ß, IL-6, IL-8, or TNF-α reduced decorin secretion in HPMC, but induced fibronectin expression. The effects were mediated in part through increased p38 MAPK and AKT/PI3K phosphorylation. Decorin abrogated the induction of fibronectin expression in mesothelial cells by PD fluids or pro-fibrotic cytokines, through decreased TGF-ßRI, p38 MAPK and AKT/PI3K phosphorylation and increased glycogen synthase kinase-3ß phosphorylation. Decorin gene-silencing resulted in increased fibronectin expression under these conditions. INTERPRETATION: Our data demonstrate anti-fibrotic actions of decorin in HPMC, when these cells are subjected to the pro-fibrotic effect of peritoneal dialysate and pro-fibrotic cytokines in PD, especially during peritonitis.

Regulation of CCN2/CTGF and related cytokines in cultured peritoneal cells under conditions simulating peritoneal dialysis.

BACKGROUND: Continuous ambulatory peritoneal dialysis (CAPD) is a major treatment modality for end-stage renal failure. The peritoneal membrane exhibits pathological changes that correlate with the duration of dialysis. These changes are due to the exposure of the peritoneum to non-physiologic peritoneal dialysis solution (PDS) with a high glucose content, and containing potentially toxic substances including glucose degradation products (GDP) and advanced glycation end products (AGE). Connective tissue growth factor (CTGF/CCN2) is one of the determinants of progressive fibrosis and peritoneal membrane dysfunction in CAPD. In this study, we examined the CCN2 expression and its regulation in peritoneal resident cells using a cell culture model. METHODS: The expression of transforming growth factor-beta (TGF-beta), CCN2 and vascular endothelial growth factor (VEGF) in human peritoneal mesothelial cells (HPMC), human peritoneal fibroblasts (HPF) or endothelial cell line EA.hy926 (EC) cultured with various PDS and their components was examined by quantitative PCR (qPCR). The modulation of CCN2 synthesis under the crosstalk between HPMC and HPF or EC was examined using a conditioned medium transfer system in which HPMC was exposed to conditioned media obtained from HPF or EC incubated with PDS and their components. The differential effects of TGF-beta, CCN2 and VEGF in inducing the expression of transcriptional factors as well as interleukin-6 (IL-6), matrix metallopeptidase 9 (MMP-9) and collagen I were examined by electrophoretic mobility-shift assay (EMSA) and qPCR. RESULTS: PDS and their components differentially modulated the expression of TGF-beta, CCN2 and VEGF in HPMC, HPF and EC. The expression of CCN2 by HPMC was significantly increased after cultured with a HPF-conditioned medium and an EC-conditioned medium. Neutralizing anti-TGF-beta antibodies reduced but not completely abolished the CCN2 synthesis in HPMC cultured with the HPF- or EC-conditioned medium. CCN2, TGF-beta and VEGF activated distinct transcriptional factors in HPMC, which resulted in divergent biological responses in terms of IL-6, MMP-9 and collagen I mRNA expression. CONCLUSION: AGE and GDPs in PDS differentially regulate the synthesis of CCN2 by peritoneal resident cells. The CCN2 synthesis by HPMC can be further amplified by TGF-beta released from HPF or EC. The differential activation of different transcriptional factors and diverse response of HPMC towards CCN2, TGF-beta and VEGF suggest that these cytokines/growth factors have an overlapping and distinct role on HPMC.

Clarithromycin-amoxycillin-containing triple therapy: a valid empirical first-line treatment for Helicobacter pylori eradication in Hong Kong?

BACKGROUND: Recent studies have suggested the eradication rate for Helicobacter pylori infection with standard amoxycillin-clarithromycin-containing triple therapy as first-line treatment have fallen below 80%. Levofloxacin-containing triple therapy was proposed as an alternative. The aim of this study is to compare the efficacy and tolerability of the standard 7-day clarithromycin-containing triple therapy against the 7-day levofloxacin-containing triple therapy, and to assess whether the classical triple therapy is still valid as empirical first-line treatment for H. pylori infection in Hong Kong. METHODS: Three hundred consecutive H. pylori-positive patients were randomized to receive either 1 week of EAL (esomeprazole 20 mg b.d., amoxycillin 1 g b.d., and levofloxacin 500 mg daily) or EAC (esomeprazole 20 mg b.d., amoxycillin 1 g b.d., and clarithromycin 500 mg b.d.). H. pylori status was rechecked by (13)C-urea breath test 6 weeks after treatment. Patients who failed either of the first-line eradication therapy were invited to undergo H. pylori susceptibility testing. RESULTS: H. pylori eradication was achieved in 128 of 150 (85.3%) patients in EAL and 139 of 150 (92.7%) patients in EAC groups, respectively (p = .043), for both intention-to-treat and per-protocol analysis. More patients in the clarithromycin- than the levofloxacin-containing therapy group developed side effects from the medication (21.3% vs 13.3%, p = .060). Nine patients (six from the EAL group and three from the EAC group) who failed their corresponding eradication therapy returned for susceptibility testing. All nine isolates were highly resistant to levofloxacin (minimum inhibitory concentration or MIC > 32 microg/mL), whereas only two of the six isolates from the EAL group were resistant to clarithromycin (MIC > 0.5 microg/mL). CONCLUSIONS: The standard 7-day clarithromycin-containing triple therapy is still valid as the most effective empirical first-line eradication therapy for H. pylori infection in Hong Kong, as prevalence of primary resistance of H. pylori to amoxycillin and clarithromycin remains low. Patients who failed their empirical first-line eradication therapy should undergo H. pylori susceptibility testing to guide further treatment.

Constitutive hypophosphorylation of extracellular signal-regulated kinases-1/2 and down-regulation of c-Jun in human gastric adenocarcinoma.

Hyperphosphorylation of extracellular signal-regulated protein kinases-1/2 (ERK1/2) is known to promote cancer cell proliferation. We therefore investigated the constitutive phosphorylation levels of ERK1/2 and the expression of its downstream targets c-Fos, c-Jun, and cyclooxygenase-2 (COX-2) in biopsied human gastric cancer tissues. Results showed that ERK1/2 phosphorylation and c-Jun expression were significantly lowered in gastric cancer compared with the non-cancer adjacent tissues. The expression of c-Fos, however, was not altered while COX-2 was significantly up-regulated. To conclude, we demonstrate that hypophosphorylation of ERK1/2 may occur in gastric cancer. Such discovery may have implication in the application of pathway-directed therapy for this malignant disease.