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Biomedical subjects

A C Ng

Publications and source records attributed to A C Ng.

At least 19 recordsLinked to original sources
PubMed2001

Correlation between Helicobacter pylori infection, gastric inflammation and serum homocysteine concentration.

BACKGROUND: Epidemiological studies have suggested a link between chronic Helicobacter pylori infection and ischemic heart disease but the underlying mechanism remains elusive. We hypothesized that H. pylori-associated chronic gastritis causes impairment of absorption of vitamin cofactors that are essential in the metabolism of homocysteine and results in hyperhomocysteinemia. MATERIALS AND METHODS: Forty-nine dyspeptic patients were studied. H. pylori infection was defined by rapid urease test and histology. Fasting serum homocysteine level, which was measured by a validated commercial fluorescence polarization immunoassay, was correlated with H. pylori infection statuses and gastric histology. H. pylori-infected patients were followed up for 24 weeks post eradication for changes in serum homocysteine concentration. RESULTS: Univariate analyses showed that serum homocysteine level correlated with increasing age (p <.001), male sex (p =.003) and smoking habit (p =.025). There was no significant difference in serum homocysteine levels between H. pylori infected and uninfected subjects (median 10.5 vs. 10.2 micromol/l). After successful eradication of the bacterium, there was no significant reduction in homocysteine level. Moreover, there was no correlation between homocysteine level and gastric histology including H. pylori density, activity and inflammation scores, presence of atrophy or intestinal metaplasia. CONCLUSIONS: The postulated link between H. pylori infection and ischemic heart disease, if it actually exists, is unlikely to be mediated through hyperhomocysteinemia.

Adult↗
PubMed2000

Helicobacter pylori infection is associated with milder gastro-oesophageal reflux disease.

BACKGROUND: We have previously demonstrated a negative relationship between the prevalence of Helicobacter pylori and gastro-oesophageal reflux disease (GERD). AIM: To study the effects of H. pylori infection on the severity of GERD. METHODS: Ethnic Chinese patients with frequent heartburn and/or endoscopic oesophagitis were studied. Endoscopic examination was performed to assess the severity of oesophagitis (modified Savary-Miller grading) and the presence of hiatus hernia. Biopsies were taken for rapid urease testing and confirmation of Barrett's oesophagus. Risk factors which may affect the severity of oesophagitis (age, sex, smoking, drinking, diabetes mellitus, hiatus hernia, H. pylori status and body mass index) were evaluated by a multiple regression model. The cagA status of H. pylori infected GERD and age-and-sex matched controls were determined by Western blot. Age-and-sex matched non-reflux patients were recruited as controls for comparison. RESULTS: Two hundred and twenty-five patients with GERD were studied, of whom 77 (34%) were infected with H. pylori. Oesophagitis and Barrett's oesophagus were found in 140 patients (62%) and six patients (3%), respectively. H. pylori infected patients had significantly less severe oesophagitis compared to the uninfected group (P=0.022). All patients with Barrett's oesophagus were uninfected. Factors that predicted severe oesophagitis included age over 60 years (P < 0.001) and hiatus hernia (P < 0.001). H. pylori infection was the only factor that showed a negative correlation with severe oesophagitis (P=0.011). The prevalence of the cagA positive strain in endoscopy-negative GERD, erosive oesophagitis and control subjects was 70, 76 and 78%, respectively (P=0.75). CONCLUSIONS: H. pylori infection is associated with milder GERD.

Adult↗
PubMed1998

A single point mutation controls the cholesterol dependence of Semliki Forest virus entry and exit.

Membrane fusion and budding are key steps in the life cycle of all enveloped viruses. Semliki Forest virus (SFV) is an enveloped alphavirus that requires cellular membrane cholesterol for both membrane fusion and efficient exit of progeny virus from infected cells. We selected an SFV mutant, srf-3, that was strikingly independent of cholesterol for growth. This phenotype was conferred by a single amino acid change in the E1 spike protein subunit, proline 226 to serine, that increased the cholesterol independence of both srf-3 fusion and exit. The srf-3 mutant emphasizes the relationship between the role of cholesterol in membrane fusion and virus exit, and most significantly, identifies a novel spike protein region involved in the virus cholesterol requirement.

Amino Acid Sequence↗
PubMed1996

Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction.

OBJECTIVE: We compare the reliability and define the role of plain film radiography and CT in the assessment of various severities of small-bowel obstruction. MATERIALS AND METHODS: A blinded retrospective analysis was done on 78 patients who underwent plain abdominal radiography, CT, and enteroclysis to assess for suspected small-bowel obstruction. The findings at enteroclysis and the clinical outcomes were used as standards of reference. RESULTS: The sensitivity of plain film radiography for revealing small-bowel obstruction was 69% (44/64), and its specificity was 57% (8/14). Overall accuracy of plain film radiography was 67% (52/78). The sensitivity and specificity of CT were 64% (41/64) and 79% (11/ 14), respectively. Overall accuracy of CT was 67% (52/78). When obstructions were classified as low- and high-grade partial obstruction, plain film radiography and CT had sensitivities of 86% (24/28) and 82% (23/28), respectively, for high-grade obstruction and 56% (20/36) and 50% (18/36), respectively, for low-grade obstruction. CT revealed the cause of the small-bowel obstruction in 95% (39/41) of those patients in who CT correctly showed the obstruction. CONCLUSION: Plain film radiography and CT had similar overall accuracies in showing small-bowel obstruction of various severities. Plain film radiography should remain the initial method of imaging patients with suspected small-bowel obstruction. The ability of CT to show the cause of small-bowel obstruction makes CT an important additional diagnostic tool when specific management issues must be addressed.

Adult↗
PubMed1993

Obstruction of the small intestine: accuracy and role of CT in diagnosis.

The reliability of abdominal computed tomography (CT) in the assessment of varying degrees of small bowel obstruction (SBO) was evaluated by using results at enteroclysis and clinical outcome as standards of reference. A blinded retrospective analysis was performed of the studies of 55 patients who underwent both CT and enteroclysis in the course of assessment for suspected SBO. Nine patients had no obstruction, 40 patients had obstruction due to adhesions, and six patients had tumor-related obstruction. CT results were used to identify correctly 63% (29 of 46) of those who had SBO and 78% (seven of nine) of the patients who did not. The overall accuracy of the CT interpretations to help establish diagnosis was 65% (36 of 55). When obstructions were classified into low- and high-grade partial obstruction, CT results could be used to identify correctly 81% (17 of 21) of high-grade SBOs and 48% (12 of 25) of low-grade SBOs. The procedure yielded two false-positive and 13 false-negative results for patients with low-grade obstruction, revealed masses in all six cases with tumor-related obstruction, and helped predict the correct cause in all true-positive cases.

Double-Blind Method↗
PubMed1989

Traumatic knee injuries: the accuracy of MRI compared with arthroscopy.

Forty-three knees in 43 patients were evaluated preoperatively with magnetic resonance imaging (MRI). Both menisci and cruciate ligaments subsequently were examined directly with arthroscopy. A grading scale was used to evaluate intrameniscal signal intensity and to predict the presence of meniscal tear using MR. Compared with arthroscopy, the sensitivity, specificity and accuracy of MRI were, respectively, 100%, 88% and 93% for tears of the medial meniscus; 72.7%, 93.7% and 88.4% for tears of the lateral meniscus; 100%, 96.7% and 97.7% for tears of the anterior cruciate ligament. There were no posterior cruciate ligament tears, and none were suggested from the images. Our results show that MRI is a valuable diagnostic aid in the management of traumatic knee injury.

Adolescent↗
PubMed1988

Patterns of calcifications and cholangiographic findings in hepatobiliary tuberculosis.

The radiologic findings on conventional examinations (plain films and cholangiograms) in a large group of patients with proven hepatobiliary tuberculosis are reviewed. The plain film findings of large "chalky" and confluent hepatic calcifications or nodal-type calcifications along the course of the common bile duct are suggestive of hepatobiliary tuberculosis. Small, discrete, scattered calcifications may be mimicked by histoplasmosis but can be differentiated from hepatobiliary tuberculosis. Obstructing defects seen on cholangiography are indicative of tuberculosis when adjacent calcifications are present. The patterns of liver calcifications could provide a clue to the diagnosis of hepatobiliary tuberculosis and its differentiation from liver calcifications of various other etiologies.

Adolescent↗
PubMed1984

Leiomyoma in a "blind pouch".

This report describes a patient with anemia and chronic diarrhea secondary to an ulcerating leiomyoma in a blind pouch. It emphasizes the clinical and radiologic difficulty in diagnosing focal lesions of the mesenteric small bowel and the need for a careful scrutiny of all segments of small bowel in a patient with unexplained anemia and diarrhea.

Adult↗
PubMed1979

Gastrointestinal perforation by chicken bones.

Four cases of gastrointestinal perforation by chicken bones are presented. Variability in the clinical manifestations generally precludes a correct preoperative diagnosis of intraabdominal chicken bone abscess. However, in 2 patients, a diagnosis was possible with plain abdominal radiographs. Although the abnormalities seen were nonspecific, the identification of a chicken bone with an associated mass or extraluminal gas collection in a patient with signs of peritonitis, mechanical bowel obstruction, or pneumoperitoneum strongly suggests the diagnosis. A history of alcoholism or wearing dentures strengthens it.

Aged↗
PubMed1977

Use of Fogarty catheter tamponade for ruptured abdominal aortic aneurysms.

A simple rapid potentially life-serving aid in the treatment of ruptured abdominal aortic aneurysms by the use of a Fogarty no. 8 French catheter is presented. In five cases at high surgical risk, further bleeding was successfully controlled by occluding the aorta proximal to the site of the ruptured aneurysm, making operative procedure easier. Four of the five patients survived the procedure. The technique of inserting the catheter via a left axillary arteriotomy and the solutions to certain technical difficulties are discussed.

Aged↗