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Biomedical subjects

M Ng

Publications and source records attributed to M Ng.

At least 19 recordsLinked to original sources
PubMed2006

The role of cytokines in mediating effects of prenatal infection on the fetus: implications for schizophrenia.

Maternal infections with bacterial or viral agents during pregnancy are associated with an increased incidence of schizophrenia in the offspring at adulthood although little is known about the mechanism by which maternal infection might affect fetal neurodevelopment. Exposure of pregnant rodents to the bacterial endotoxin, lipopolysaccharide (LPS), results in behavioral deficits in the adult offspring that are relevant to schizophrenia. It is however unknown whether these effects are due to the direct action of the inflammatory stimulus on the developing fetus, or due to secondary immune mediators (cytokines) activated at maternal/fetal sites. In this study we sought to elucidate the site of action of LPS, following a single intraperitoneal (i.p.) injection, in pregnant rats at gestation day 18. Animals received 5 muCi of iodinated LPS ((125)I-LPS) and its distribution was assessed in maternal/fetal tissues (1-8 h). In addition, induction of the inflammatory cytokines, TNF-alpha, IL-1beta and IL-6, was measured in maternal/fetal tissues following maternal LPS challenge (0.05 mg/kg, i.p.) (2-8 h). (125)I-LPS was detected in maternal tissues and placenta, but not the fetus. This distribution was accompanied by significant increases in TNF-alpha, IL-1beta and IL-6 in maternal plasma and placenta, but not in fetal liver or brain. A significant increase in IL-1beta was however detected in fetal plasma, possibly due to transfer from the maternal circulation or placenta. Collectively, these data suggest that effects of maternal LPS exposure on the developing fetal brain are not mediated by the direct action of LPS, but via indirect actions at the level of the maternal circulation or placenta.

Animals↗
PubMed2006

Value of low-dose 2 x 2 Gy palliative radiotherapy in advanced low-grade non-Hodgkin's lymphoma.

Low-dose radiotherapy over the last decade has been reported to provide effective palliation for patients with low-grade non-Hodgkin's lymphoma. In this retrospective case series of 10 patients, we report our early experience using low-dose radiotherapy (usually 2 x 2 Gy) for patients with advanced-stage follicular, mucosal associated lymphoid tissue, mantle cell and small lymphocytic lymphomas. Median follow up was 27 weeks. Response rates were high (complete response, 70%; partial response, 20%), the response durable and the toxicity was minimal (no toxicity greater than grade 1). Low-dose irradiation is an effective treatment option for patients with low-grade lymphomas with local symptoms.

Aged↗
PubMed2005

Gemcitabine, cisplatin and methylprednisolone (GEM-P) is an effective salvage regimen in patients with relapsed and refractory lymphoma.

There is currently no standard salvage chemotherapy regimen in relapsed and refractory lymphoma. Gemcitabine is a novel nucleoside analogue, which acts synergistically with cisplatin both in vitro and in clinical studies. We evaluated the combination of gemcitabine, cisplatin and methylprednisolone (GEM-P) in 41 heavily pretreated patients with relapsed and refractory Hodgkin's and non-Hodgkin's lymphoma. The best-achieved response rate (RR) was 79% (95% CI 64-91), with a complete RR of 21%. In patients with chemo-resistant disease, the RR was 63%. Myelosuppression was the main toxicity, the incidence of Grade 3 or 4 anaemia, neutropenia and thrombocytopenia was 17.1, 61.0 and 53.7% respectively. Only one patient had neutropenic sepsis and none of the patients suffered from haemorrhage. Grade 3 or 4 nonhaematological toxicity was minimal and stem cell mobilisation was not inhibited. GEM-P is an effective salvage regimen and its use prior to autologous stem cell transplant warrants further investigation.

Adolescent↗
PubMed2004

Outcome of emergency ERCP for acute cholangitis in patients 90 years of age and older.

BACKGROUND: An increasing proportion of the general population across the Western World now survives to an advanced age. However, there is limited data on the outcome of therapeutic endoscopic retrograde cholangiopancreatography in patients above 90 years of age with severe acute cholangitis. AIM: To determine the relative frequency of postendoscopic retrograde cholangiopancreatography complication in this group of patients. METHODS: The postendoscopic retrograde cholangiopancreatography complications related outcome of 64 patients aged 90 years and above (Group 1) with severe acute cholangitis were retrospectively compared with 165 patients under the age of 90 years (Group 2). RESULTS: The postendoscopic retrograde cholangiopancreatography complication rate was 4.7% (three patients) in Group 1 and 7.3% (12 patients) in Group 2. There was no significant difference in the postendoscopic retrograde cholangiopancreatography complication rate between the two groups (P = 0.567). The relative frequency of 30-day mortality was 7.8% (five patients) in Group 1 and 4.2% (seven patients) in Group 2 (P = 0.227). CONCLUSION: Urgent biliary decompression with endoscopic retrograde cholangiopancreatography in patients 90 years of age and older with severe acute cholangitis is a safe and effective procedure in the hands of highly skilled endoscopists and is not associated with increased morbidity or mortality even in this group of high risk patients.

Acute Disease↗
PubMed2004

The role of cholecystectomy in reducing recurrent gallstone pancreatitis.

BACKGROUND AND STUDY AIM: Endoscopic sphincterotomy (ES) or cholecystectomy can prevent recurrent acute pancreatitis (RAP) in patients with gallstone-related pancreatitis. However, it is unknown whether cholecystectomy after ES offers additional benefit in preventing RAP in these patients. This is a retrospective study to assess whether cholecystectomy can decrease the incidence of RAP in patients with gallstone-related pancreatitis. PATIENTS AND METHODS: Records from 139 patients with gallstone-related pancreatitis were analyzed. Of these, 58 patients had gallbladder stones with concomitant common bile duct (CBD) stones and 81 patients had gallbladder stones without CBD stones. Of the 58 patients who had both gallbladder and CBD stones, 37 (63.8 %) did not undergo cholecystectomy after ES (group 1) and 21 patients (36.2 %) did undergo cholecystectomy after ES (group 2). Of the 81 patients who had gallbladder stones but who did not have CBD stones, 54 (66.7 %) did not undergo cholecystectomy (group 3) and 27 (33.3 %) did undergo cholecystectomy (group 4). RESULTS: At the time of analysis, three patients (8.1 %) in group 1 and three patients (14.3 %) in group 2 developed RAP. There was no significant difference in the estimated probability of occurrence of RAP over time between group 1 and group 2 ( P = 0.41). However, there was a significantly higher probability of patients developing RAP over time in group 3 compared with group 4 (6/54 vs. 0/27 respectively, P = 0.04). CONCLUSION: In patients with gallbladder stones without CBD stones, cholecystectomy can decrease the incidence of RAP. In patients with both gallbladder and CBD stones, however, the risk of RAP was not further reduced by cholecystectomy after ES and complete removal of CBD stones.

Aged↗
PubMed2004

Cetuximab (Erbitux)--an emerging targeted therapy for epidermal growth factor receptor-expressing tumours.

The epidermal growth factor receptor (EGFR) provides a rational target for cancer therapy as it is commonly over-expressed in a variety of solid rumours, and deregulation of its activity is associated with resistance to chemotherapy and radiotherapy and a poorer prognosis. Cetuximab is a new monoclonal chimeric antibody directed against the EGFR. It has demonstrable activity in a number of tumour types both in combination with chemotherapy and radiotherapy and on its own. The potential to combine chemotherapy and radiotherapy with cetuximab and increase efficacy without significantly increasing toxicity provides an exciting advancement in the treatment of cancers.

Antibodies, Monoclonal↗
PubMed2003

Retained common bile duct stones: a comparison between biliary stenting and complete clearance of stones by electrohydraulic lithotripsy.

BACKGROUND: There is some uncertainty as to whether high-risk patients with difficult common bile duct stones should be subjected to a further endoscopic procedure for the complete removal of stones by electrohydraulic lithotripsy or whether permanent biliary stenting should be performed. AIM: To compare the outcome of permanent biliary stenting with electrohydraulic lithotripsy in this group of patients. METHODS: In a prospective study, 36 patients with difficult common bile duct stones were investigated: 19 underwent double pigtail insertion (stent group), whereas 17 underwent complete clearance of stones (electrohydraulic lithotripsy). RESULTS: In the electrohydraulic lithotripsy group, successful stone clearance was achieved in 76.5%, whereas, in the stent group, the success of stenting was 94.7%. A significant difference was detected in the actuarial incidence of recurrent acute cholangitis when the electrohydraulic lithotripsy group was compared with the stent group [one patient (7.7%) vs. 12 patients (63.2%), respectively; P = 0.002, log rank test]. A significant difference was detected in the actuarial frequency of mortality between the electrohydraulic lithotripsy and stent groups [seven patients (41.2%) vs. 14 patients (73.7%), respectively; P = 0.01, log rank test]. CONCLUSIONS: The removal of difficult common bile duct stones by electrohydraulic lithotripsy and further endoscopic retrograde cholangiopancreatography has a high success rate and a low complication rate even in the elderly.

Aged↗
PubMed2003

Association of interleukin 1B gene polymorphism and gastric cancers in high and low prevalence regions in China.

AIM: Our aim was to study the relationship between interleukin 1B (IL-1B) polymorphism, Helicobacter pylori infection, and gastric cancer in high prevalent (Shanxi) and low prevalent (Guangdong) regions in China. METHOD: Genomic DNA was extracted from peripheral blood of 192 healthy volunteers, 84 gastric cancer patients from Guangdong and 169 healthy volunteers, and 86 gastric cancer patients from Shanxi. Polymorphisms in IL-1B that encodes IL-1beta and IL-1RN that encodes IL-1 receptor antagonist were analysed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). These polymorphic sites include promoter regions of IL-1B at positions +3954, -511 (C-T transition), and -31 (T-C transition), and IL-1RN variable tandem repeats. RESULTS: In the low prevalence region, the frequencies of the IL-1B +3954 T/T and IL-1RN *2/*2 genotypes were similar. IL-1B -511T/T genotype frequency was significantly higher among patients with gastric cancer (25.0%) than control subjects (12.5%) (chi2=6.7, p=0.01). In the high prevalence region, the frequencies of the IL-1B +3954T/T and -511T/T genotypes and the IL-1RN *2/*2 genotype in the cancer and control groups were similar. IL-1B -31C/C genotype frequency was significantly higher among patients with gastric cancer (90.0%) than controls (78.0%) (chi2=5.0, p=0.025). Compared with the low prevalence region, control subjects from the high prevalence region had a higher frequency of the IL-1B -511T/T genotype (23.0% v 12.5%; chi2=7.0, p<0.008). While H pylori infection alone had only a modest effect on the risk of gastric cancer development (odds ratio (OR) 5.0 (95% confidence interval (CI) 1.5-16.3)), combined with the IL-1B -511T/T genotype the risk was markedly elevated (OR 17.1, 95% CI 3.8-76.4). CONCLUSION: IL-1B -511T/T genotypes are associated with gastric cancer in China. The effect of IL-1B polymorphism is less obvious in areas of high prevalence for gastric cancer.

Adult↗
PubMed2001

A crucial role of macrophages in the immune responses to oral DNA vaccination against hepatitis B virus in a murine model.

In the previous study, we had shown that live oral vaccination with Salmonella typhimurium delivering plasmid DNA-HBsAg (oral DNA vaccine) evoked a vigorous T cell response and a weak antibody response with predominant subclass IgG2a in mice, suggesting a significant involvement by professional antigen presenting cells (APC). In the present study, this possibility was further studied by infecting peritoneal macrophages (MPhi) with the oral DNA vaccine. Although, the infected cells could only express low level of the viral antigen, they nevertheless stimulated a vigorous lymphocyte proliferation of splenocytes from immune mice, induced these cells to elaborate interferon-gamma and stimulated development of HBV-specific cytotoxicity against target cells expressing the viral antigen. Infusion of the infected MPhi evoked a vigorous Th 1 and cytotoxic T lymphocyte (CTL) response and a weak IgG2a antibody response in mice, which was essentially the same as response to the oral DNA vaccine. In contrast, recombinant protein vaccine evoked a vigorous IgG1 antibody response and a weak T cell response. While, given intramuscularly, the same plasmid DNA vaccine as that contained in the oral DNA vaccine evoked a vigorous IgG1 antibody response and a moderate T cell response in these animals. It was concluded that professional APC may orchestrate the immune response to live oral DNA vaccine and it was of interest to note that different vaccine formulation and routes of administration evoke distinct immune response to HBV.

Administration, Oral↗
PubMed2001

Function and evolution of the plant MADS-box gene family.

The function of MADS-box genes in flower and fruit development has been uncovered at a rapid pace over the past decade. Evolutionary biologists can now analyse the expression pattern of MADS-box genes during the development of different plant species, and study the homology of body parts and the evolution of body plans. These studies have shown that floral development is conserved among divergent species, and indicate that the basic mechanism of floral patterning might have evolved in an ancient flowering plant.

Animals↗
PubMed2001

Acute cholangitis--predictive factors for emergency ERCP.

BACKGROUND: Acute cholangitis varies in severity from a mild form to severe cases which require urgent biliary decompression. AIM: This study was undertaken in order to develop a prognostic scoring system that can be used to predict which patients are likely to require emergency endoscopic retrograde cholangiopancreatogram (ERCP) upon admission. METHODS: This is a prospective study of 142 consecutive patients with acute cholangitis. Emergency ERCP was performed in patients who did not respond to medical therapy. RESULTS: Thirty-one patients (21.8%) required emergency ERCP. A maximum heart rate of more than 100/min, albumin of less than 30 g/L, bilirubin of more than 50 micromol/L and prothrombin time of more than 14 s on admission were associated with failure of medical treatment and the need for emergency ERCP (P=0.001, < 0.001, 0.006 and 0.004, respectively). By using these four factors in a scoring system, 50.7% of those with a score of one or more required emergency ERCP compared with 1.5% of those with none of the four risk factors (P < 0.001). This scoring system has a sensitivity of 96.8% and a specificity of 59.6%. CONCLUSIONS: As patients with severe acute cholangitis show a higher mortality, we recommend that emergency ERCP be performed in patients with one or more of the four prognostic factors.

Acute Disease↗
PubMed2001

Safety and patient experience with transtympanic electrocochleography.

OBJECTIVES/HYPOTHESIS: Transtympanic electrocochleography (t-ECOG) is a sensitive diagnostic instrument used for Meniere's disease. It is sensitive by virtue of the recording electrode's position on the promontory of the cochlea where the signals are generated. There is concern about the invasive nature of t-ECOG in comparison to extratympanic recording techniques. The purpose of this study was to examine the safety issues, complications, and patient experience with t-ECOG. STUDY DESIGN: Observational study utilizing retrospective chart review and patient survey. METHODS: The medical records of 205 patients who underwent t-ECOG were reviewed for complications. Complications included persistent tympanic membrane perforation, hearing loss, otitis media, otitis externa, ear canal injury, hemotympanum, and pain. An additional 36 patients undergoing t-ECOG were surveyed on subjective measures such as pain during topical anesthesia of the tympanic membrane, during transtympanic placement of the needle electrode, and during the test procedure and overall experience with t-ECOG. RESULTS: There was one case of a nonhealed, persistent perforation in the setting of acute otitis media directly as a result of t-ECOG. Two patients developed otitis media, and three patients had ear pain for up to 5 days. All 36 patients felt the procedure to be tolerable with minimal discomfort. CONCLUSIONS: Transtympanic electrocochleography may be performed with good patient acceptance and infrequent complications.

Audiometry, Evoked Response↗
PubMed2001

Activation of the Arabidopsis B class homeotic genes by APETALA1.

Proper development of petals and stamens in Arabidopsis flowers requires the activities of APETALA3 (AP3) and PISTILLATA (PI), whose transcripts can be detected in the petal and stamen primordia. Localized expression of AP3 and PI requires the activities of at least three genes: APETALA1 (AP1), LEAFY (LFY), and UNUSUAL FLORAL ORGANS (UFO). It has been proposed that UFO provides spatial cues and that LFY specifies competence for AP3 and PI expression in the developing flower. To understand the epistatic relationship among AP1, LFY, and UFO in regulating AP3 and PI expression, we generated two versions of AP1 that have strong transcriptional activation potential. Genetic and molecular analyses of transgenic plants expressing these activated AP1 proteins show that the endogenous AP1 protein acts largely as a transcriptional activator in vivo and that AP1 specifies petals by regulating the spatial domains of AP3 and PI expression through UFO.

Arabidopsis↗
PubMed2001

Microvessel density, vascular endothelial growth factor and its receptors Flt-1 and Flk-1/KDR in hepatocellular carcinoma.

Assessment of angiogenesis may yield important information for an effective antiangiogenic treatment for hepatocellular carcinoma (HCC) because HCC is characteristically hypervascular We examined the relationship of microvessel density (MVD), vascular endothelial growth factor (VEGF), and VEGF receptors Flt-1 and Flk-1/KDR in 50 patients with HCC and in 3 hepatoma cell lines. VEGF messenger RNA (mRNA) was overexpressed in 26 tumors (52%), and the 3 VEGF isoforms (121, 165, and 189) were present in high frequencies. Flt-1 mRNA was overexpressed in 34 tumors (68%), with levels significantly increased in HCCs compared with the nontumorous livers. Tumor Flt-1 mRNA significantly correlated with tumor VEGF mRNA levels. Within the group of tumors 8.5 cm or less in diameter, tumors with intrahepatic metastasis in the form of tumor microsatellite formation had significantly higher VEGF mRNA levels. MVD assessed by immunohistochemical analysis with CD34 antibody was inversely related to tumor size. Angiogenesis as assessed by MVD and tumor VEGF expression seems to have a more important role in tumor growth and intrahepatic metastasis in smaller HCCs. The differential up-regulation of Flt-1 suggests that it may have an important role in angiogenesis in HCC.

Adult↗
PubMed2001

What if pediatric residents could bill for their outpatient services?

OBJECTIVE: We prospectively studied the potential of billing and coding practices of pediatric residents in outpatient clinics and extrapolated our results to assess the financial implications of billing inaccuracies. Using Medicare as a common measure of "currency," we also used the relative value unit (RVU) and ambulatory payment class methodologies as means of assessing the productivity and financial value of resident-staffed pediatric clinics. METHODS: Residents were asked to submit voluntarily shadow billing forms and documentation of outpatient clinic visits. Documentation of work was assessed by a blinded reviewer, and current procedure terminology evaluation and management codes were assigned. Comparisons between resident codes and calculated codes were made. Financial implications of physician productivity were calculated in terms of dollar amounts and RVUs. Resource intensity was measured using the ambulatory payment class methodology. RESULTS: A total of 344 charts were reviewed. Coding agreement for health maintenance visits was 86%, whereas agreement for acute care visits was 38%. Eighty-three percent of coding disagreement in the latter group was resulting from undercoding by residents. Errors accounted for a 4.79% difference in potential reimbursement for all visit types and a 19.10% difference for acute care visits. No significant differences in shadow billing discrepancies were found between different levels of training. Residents were predicted to generate $67 230, $87 593, and $96 072 in Medicare revenue in the outpatient clinic setting during each successive year of training. On average, residents generated 1.17 +/- 0.01 and 0.81 +/- 0.02 work RVUs for each health maintenance visit and office visit, respectively. Annual productivity from outpatient clinic settings was estimated at 548, 735, and 893 work RVUs in the postgraduate levels 1, 2, and 3, respectively. CONCLUSION: When pediatric residents are not trained adequately in proper coding practices, the potential for billing discrepancies is high and potential reimbursement differences may be substantial. Discussion of financial issues should be considered in curriculum development.

Accounting↗
PubMed2001

Prokaryotical expression of structural and non-structural proteins of hepatitis G virus.

AIM: To study the epitope distribution of hepatitis G virus (HGV) and to seek for the potential recombinant antigens for the development of HGV diagnostic reagents. METHODS: Fourteen clones encompassing HGV gene fragments from core to NS3 and NS5 were constructed using prokaryotic expression vector pRSET and (or) pGEX, and expressed in E.coli. Western blotting and ELISA were used to detect the immunoreactivity of these recombinant proteins. RESULTS: One clone with HGV fragment from core to E1 (G1), one from E2 (G31), three from NS3 (G6, G61, G7), one from NS5B (G821) and one chimeric fragment from NS3 and NS5B (G61-821) could be expressed well and showed obvious immunoreactivity by Western blotting. One clone with HGV framment from NS5B (G82) was also well expressed, but could not show immunoreactivity by Western blotting. No obvious expression was found in the other six clones. All the expressed recombinant proteins were in inclusion body form, except the protein G61 which could be expressed in soluble form. Further purified recombinant proteins G1, G31, G61, G821 and G61-821 were detected in indirected ELISA as coating antigen respectively. Only recombinant G1 could still show immunoreactivity, and the other four recombinant proteins failed to react to the HGV antibody positive sera. Western blotting results indicated that the immunoactivity of these four recombinant proteins were lost during purification. CONCLUSION: Core to E1, E2, NS3 and NS5 fragment of HGV contain antigenic epitopes, which could be produced in prokaryotically expressed recombinant proteins. A high-yield recombinant protein (G1) located in HGV core to E1 could remain its epitope after purification, which showed the potential that G1 could be used as a coating antigen to develop an ELISA kit for HGV specific antibody diagnosis.

Blotting, Western↗