Biomedical subjects

K Y Ho

Publications and source records attributed to K Y Ho.

At least 37 records · Page 2Linked to original sources

PubMed2000

Esophageal mucosal acid sensitivity can coexist with normal pH recording in healthy adult volunteers.

We aimed to determine whether healthy volunteers with normal pH monitoring study results experienced heartburn or discomfort during an esophageal acid perfusion test. We performed an esophageal acid perfusion test, followed by ambulatory esophageal pH monitoring, in 15 healthy and asymptomatic volunteers (aged 19 to 34 years). The results of the acid perfusion test were correlated with those of the pH monitoring. Three subjects (20%) reported chest discomfort during acid perfusion. The pH data in all subjects were within our laboratory reference ranges; the median (range) percent total time at pH < 4 being 1.7 (0.2-4.0)% [laboratory reference, median (range), 3.0 (0.2-4.0)%]. We concluded that direct infusion of acid onto the distal esophagus can produce discomfort akin to that of gastroesophageal reflux disease in asymptomatic adult volunteers, even in the absence of excessive esophageal acid exposure.

Acid-Base Equilibrium↗

PubMed2000

Otogenic brain abscess--a case report.

Brain abscess is one of the life-threatening complications of otitis media. Mortality and morbidity have decreased with the advent of antibiotic therapy. More frequently encountered in cases of acute otitis media in the preantibiotic era, in recent years otogenic brain abscess was noticed almost only in patients of chronic otitis media with cholesteatoma. A case of brain abscess in a 49-year-old female was initially diagnosed as a headache. A high resolution computed tomography (HRCT) scan of the temporal bones later revealed that there were two abscesses over the right side temporal lobe. A modified radical mastoidectomy was performed. Cultures of the middle ear cholesteatoma later grew Pseudomonas aeruginosa and Strenotrophomonas maltophilia. Antibiotic therapy was carried on for three months postoperatively. The patient improved but retained a conductive hearing loss.

Brain Abscess↗

PubMed2000

Normal bowel habits and prevalence of functional bowel disorders in Singaporean adults--findings from a community based study in Bishan. Community Medicine GI Study Group.

BACKGROUND/AIM OF STUDY: Data on the epidemiology of bowel frequency and functional bowel disorders in the East are limited. The aims of this study were to determine the most common bowel frequency and the prevalence of functional bowel disorders in Singaporean adults. METHODS: A cross sectional study, using a reliable and valid questionnaire was carried out in a random sample of residents aged 16 years and above in Bishan, 68% responded (n = 271). RESULTS: The most common (59.0 +/- 6.5%) bowel frequency was once a day with 96.8 +/- 5.6% of individuals having bowel frequency between 3 times/week and 3 times/day. The prevalences of irritable bowel syndrome, chronic constipation and chronic diarrhoea were 3.2 +/- 2.3%, 7.3 +/- 3.5% and 6.9 +/- 3.4%, respectively. Women were found to have a lower bowel frequency (p < 0.001) and a higher prevalence of chronic constipation (11.3 +/- 6.0% vs. 3.6 + 3.5%, p < 0.05) than men. CONCLUSIONS: Normal bowel frequency may be defined as bowel movements between 3 times per week and three times per day. The prevalence of irritable bowel syndrome in the general population of Singapore was low compared with those reported in the West.

Adolescent↗

PubMed1999

[Contrast-enhanced magnetic resonance angiography].

Contrast-enhanced magnetic resonance angiography (MRA) involves intravenous injection of a contrast medium that increases the signal intensity of blood by shortening its T1 value. With contrast-enhanced MRA the acquisition time is short (less than 40 s for the abdominal aorta and the iliac vessels) and the images obtained can be interpreted accurately. The contrast medium currently in use virtually never causes adverse effects and is not nephrotoxic. After obtaining a three-dimensional dataset projections can be made at will. In addition, the individual partitions should be evaluated. The postprocessing time is about 15 min per examination. Current clinical applications are diagnostic examination of (stenoses of) the aortic arch and its branches, the thoracic and abdominal aorta, the visceral vessels, the renal arteries and the peripheral arteries. The sensitivity and specificity of contrast-enhanced MRA in most studies amount to over 90%.

Aortic Diseases↗

PubMed1999

MR angiography of run-off vessels.

Magnetic resonance angiography has taken a huge step forward since the introduction of contrast-enhanced MR angiography using gadolinium chelates. The more conventional MR angiographic techniques, such as time-of-flight and phase-contrast MR angiography, have been ousted by contrast-enhanced MR angiography in most vascular areas. However, in imaging the lower extremities, the major obstacle is the length of the vascular tree. In order to cover the entire peripheral vasculature, at least two to three fields of view are required. Using contrast-enhanced MR angiography, the best results are obtained if the vessels of interest are imaged during passage of a bolus of contrast material. Vessel-to-background contrast in subsequent acquisitions using subsequent injections of contrast material is hampered by recirculation and leakage of previously injected gadolinium, enhancing both the venous system and surrounding tissue. To overcome this problem several research groups have come up with various solutions. The three main strategies employed can be classified as either bolus catch, bolus chase, or bolus track techniques. The purpose of this article is to explain working mechanisms of the three bolus imaging strategies for imaging both inflow and outflow vessels of the lower extremities, to show their advantages and disadvantages, and to review results described in the literature in imaging patients using these techniques.

Contrast Media↗

PubMed1999

Peripheral MR angiography.

Atherosclerotic disease of the lower extremities is a common disorder in western society. Its debilitating nature calls for accurate diagnosis and treatment. The gold standard for diagnosing this disease by depiction of vessel morphology is X-ray angiography (either conventional or digital subtraction angiography). However, the invasive nature of this technique and the possible harmful effects of iodinated contrast agents have led to the idea that non-invasive MR angiography might be a good alternative for acquiring information about vessel morphology. Most extensively studied was time-of-flight MR angiography. Although first results with this technique were encouraging, it is now apparent that time-of-flight MR angiography is hampered by the virtue of which it exists, since blood flow not only generates vessel-to-background contrast, but is also the cause of disturbing artifacts. However, with the introduction of minimally invasive contrast-enhanced MR angiography, using gadolinium chelates to reduce the T1 of blood, image quality has improved dramatically. Moreover, using contrast-enhanced MR angiography, high-resolution three-dimensional data about the entire peripheral vascular tree can be obtained within several minutes, which might make MR angiography a true competitor of X-ray angiography as a diagnostic tool in the clinical work-up of a patient with complaints of peripheral atherosclerosis. The purpose of this article is to explain working mechanisms and usefulness of both time-of-flight and contrast-enhanced MR angiography.

Arterial Occlusive Diseases↗

PubMed1999

Features that may predict hospital admission following outpatient therapeutic ERCP.

BACKGROUND: Some patients are admitted following outpatient therapeutic ERCP because of adverse events. This study aimed to identify factors that may predict such admissions. METHODS: We prospectively studied admissions for post-ERCP adverse events in 415 consecutive patients undergoing outpatient therapeutic ERCP. Potentially relevant predictors of admission were assessed by univariate analysis and in case of significance included in a multivariate analysis. RESULTS: Admission was necessary in 41 patients (9.9%) because of complications and in 63 (15.2%) for observation of adverse events that did not progress to definable complications. Potential predictors of admission were evaluated comparing patients who required more than an overnight admission (n = 63) with those who did not (n = 352). Multivariate analysis identified three factors that were significant: pain during the procedure (odds ratio 3.8: 95% CI [1.8, 7.9]), history of pancreatitis (odds ratio 2.3: 95% CI [1.1, 4.7]) and performance of sphincterotomy (odds ratio 2.2: 95% CI [1.1, 4.3]). The presence of all these features was associated with a 66.7% likelihood of admission, whereas the absence of pain during the procedure, history of pancreatitis and performance of sphincterotomy made admission likely in only 11.0%, 9.8% and 10.7%, respectively, of the cases. CONCLUSIONS: The occurrence of pain during the procedure, a history of pancreatitis and the performance of sphincterotomy were independent predictors of admission following outpatient therapeutic ERCP.

Adult↗

PubMed1999

Patterns of consultation and treatment for heartburn: findings from a Singaporean community survey.

BACKGROUND: The prevalence of reflux-type symptoms among community individuals in Singapore is low. AIM: To describe the healthcare-seeking behaviour of those subjects with heartburn. METHODS: A cross-sectional survey, using a reliable and valid questionnaire, was carried out on a race-stratified random sample of residents, aged 21-95 years, in a Singaporean town; 93% responded (n = 696). RESULTS: The ethnic-adjusted prevalence of heartburn for the past 1-year was 4.6%. Sixteen (30%) of the 53 heartburn sufferers had sought consultation for their symptoms. They were more likely to have severe heartburn (P<0.001), and to have complained of nocturnal awakening due to heartburn (P<0.05) than those who did not present to medical attention. Ethnic origin did not influence the consultation pattern. Only 18 (34%) of the 53 heartburn sufferers received pharmacological therapy for their symptoms. The most commonly used medication was antacid. Medication use was associated with symptom severity (P<0.05), but not ethnicity. CONCLUSIONS: Heartburn is uncommon in the general population of Singapore. Few heartburn sufferers seek medical attention, and most do not receive medications for symptomatic control. The decision to seek medical advice and/or to medicate was generally linked to symptom severity, but not to ethnicity.

Adult↗

PubMed1999

Reduced expression of APC and DCC gene protein in breast cancer.

AIMS: To investigate if the adenomatous polyposis coli (APC) protein and the deleted in colorectal cancer (DCC) protein expression can be demonstrated by an immuno-histochemical method and to study the role of APC and DCC gene inactivation in the development and progression of breast cancer using colorectal cancer as a control model. METHODS AND RESULTS: The reduced or loss of protein expression of the APC and DCC genes was studied in 27 surgical specimens of primary breast cancer using an immunohistochemical method. Reduced or lost expression was identified in 11 out of 27 samples (40.7%) for the APC gene and 15 out of 27 samples (55.6%) for the DCC gene. No statistically significant difference was observed between the reduced or lost protein expression and the histological grading of breast tumour for both the APC and the DCC gene. CONCLUSIONS: Both gene proteins can be demonstrated by the immunohistochemical method. Reduced or loss of APC and DCC gene product were observed in 40.7% and 55.6% cases of primary breast cancer respectively. Further work is required to investigate the significance of the finding.

Adenomatous Polyposis Coli Protein↗

PubMed1999

Peptic ulcer and gastritis in uraemia, with particular reference to the effect of Helicobacter pylori infection.

AIMS: To determine: (i) the prevalence of histological gastritis and peptic ulcer; and (ii) the clinical features of peptic ulcer, in patients with end-stage renal failure. METHODS: Upper endoscopy was performed by a single observer in 268 patients with end-stage renal failure over a 6-year period. Gastric histology and Helicobacter pylori status were studied in 40 consecutive subjects in whom there were no contraindications for gastric biopsy and who had not used antibacterial drugs in the preceding 4 weeks. As there are only limited data for healthy volunteers in Singapore, 33 age-, sex- and race-matched patients with functional dyspepsia from an earlier drug trial and 18 healthy volunteers who were not age-matched were used as controls. The clinical features of 43 consecutive uraemic patients with peptic ulcer were compared with those of 118 consecutive non-uraemic peptic ulcer patients seen by the same author. RESULTS: Among uraemic patients, histological gastritis was less common, compared with healthy volunteers and functional dyspepsia patients. Helicobacter pylori infection as assessed by histology was also less common among uraemic patients compared with functional dyspepsia patients, but the difference was not statistically significant on serological assessment. Uraemic patients with ulcer had an equal sex ratio, in contrast to a male preponderance among peptic ulcer patients with normal renal function. Uraemic patients with ulcer were more likely to be pain-free, to present with haemorrhage, to have multiple ulcers and postbulbar duodenal ulcers, but were less likely to have H. pylori infection. Among uraemic subjects, the prevalence of H. pylori infection was similar whether or not peptic ulcer was present. CONCLUSIONS: The prevalence of histological gastritis was lower in uraemic patients when compared with patients with functional dyspepsia and healthy volunteers. Peptic ulcers in uraemic subjects have different clinical characteristics from peptic ulcer in non-uraemic subjects.

Adolescent↗

PubMed1999

A prospective study of the clinical features, manometric findings, incidence and prevalence of achalasia in Singapore.

BACKGROUND: This study aimed to describe the clinical features, manometric findings, prevalence and incidence of achalasia in Singapore. METHODS: A total of 615 new patients referred for oesophageal manometry between 1989 and 1996 were examined prospectively. Twenty-four men and 25 women fulfilled the manometric and clinical criteria for achalasia. RESULTS: Their median age of onset of symptoms was 37 years (range 15-71) and 37% first developed symptoms after the age of 50 years. The presenting symptoms were dysphagia (100%), regurgitation (80%), weight loss (67%) and chest discomfort (33%). Five patients (10%) had a history of benign (mostly autoimmune) thyroid disorders. Endoscopy was reported as normal in 10/43 patients (23%) and achalasia was suggested in only 31 (72%) of 43 barium examinations. Lower oesophageal sphincter (LOS) dysfunction was present in 82% of cases. Using data from medical records and from a survey of gastroenterologists and surgeons in Singapore, the prevalence (in 1996) and incidence of achalasia in Singapore were estimated to be 1.8 per 100000, and 0.3 per 100000 per year, respectively. The incidence was significantly lower in Malays than Chinese or Indians. The age-specific incidence of achalasia for both genders followed a bimodal distribution with the larger peak in the sixth decade. No cases of oesophageal carcinoma were identified among these patients. CONCLUSION: Achalasia is an uncommon condition in Singapore. The clinical and manometric features were similar to those described in Western countries.

Adolescent↗

PubMed1999

Different prevalences of reflux oesophagitis and hiatus hernia among dyspeptic patients in England and Singapore.

OBJECTIVE: To compare the frequency of reflux oesophagitis and hiatus hernia in dyspeptic patients in England with that in Singapore. DESIGN: Demographic, clinical and endoscopic findings in consecutive dyspeptic patients seen in England and Singapore by the same clinician were compared. The association of various factors with the occurrence of hiatus hernia and oesophagitis was analysed by logistic regression. SETTING: District general hospital in England and university hospital in Singapore. PARTICIPANTS: The English series comprised 212 consecutive patients, and 173 patients were seen in Singapore. RESULTS: Reflux oesophagitis and hiatus hernia were found in 52 (25%) and 50 (49%) of the English patients, and 12 (6%) and 7 (4%) of the Singapore patients, respectively (P<0.005 in each case). Race, body mass index and age were independently associated with hiatus hernia (odds ratios 3.07, 1.08 and 1.04, respectively). The risk factors for oesophagitis were race, sex, body mass index and age (odds ratios 4.04, 2.37, 1.11 and 1.02, respectively). If hiatus hernia was included in the analysis, the risk factors were hiatus hernia, sex, race and body mass index (odds ratios 20.10, 3.07, 2.81 and 1.09, respectively). CONCLUSIONS: Reflux oesophagitis and hiatus hernia are more common in English dyspeptic patients compared to those in Singapore. The most important risk factor for both oesophagitis and hiatus hernia is race.

Adult↗

PubMed1999

Reflux esophagitis patients in Singapore have motor and acid exposure abnormalities similar to patients in the Western hemisphere.

OBJECTIVE: Endoscopic esophagitis is less common in the East than in the West. The reason for this is unknown. This study examines prospectively the relationship between endoscopic esophagitis and lower esophageal sphincter pressure, distal esophageal contractility, esophageal peristaltic performance, esophageal acid exposure, gastric acid output, and Helicobacter pylori (H. pylori) status in a consecutive series of Asian patients. METHODS: Esophageal manometry and ambulatory pH monitoring were carried out in 48 patients with endoscopic esophagitis and 208 patients with symptoms suspicious of gastroesophageal reflux disease but without esophagitis. Gastric acid output and H. pylori serology were determined in 22 of the esophagitis group and 36 of the nonesophagitis group. RESULTS: Compared to the nonesophagitis patients, esophagitis patients had a higher prevalence of hypotensive lower esophageal sphincter (49% vs 24%, p < 0.001), impaired esophageal contractility (45% vs 22%, p < 0.005), poor peristaltic performance (23% vs 12%, p < 0.05), and pathological acid reflux (48% vs 27%, p < 0.005). However, there was no difference in the two groups with respect to gastric acid output and H. pylori positivity. CONCLUSIONS: Lower esophageal sphincter competence, esophageal peristaltic contractility, and esophageal acid exposure were important factors in the pathogenesis of reflux esophagitis--results identical to Western studies. Gastric acid output per se and H. pylori infection might not be responsible for susceptibility to esophagitis.

Adult↗

PubMed1999

Antioxidant activity of tannin components from Vaccinium vitis-idaea L.

Reactive oxygen molecules have been implicated as important pathological mediators in many clinical disorders and periodontal disease. To provide possible alternative treatment of periodontal disease, six tannins isolated from Vaccinium vitis-idaea L. were evaluated for anti-lipid peroxidation, anti-superoxide formation and free radical scavenging activity. The results showed that cinnamtannin B1 displayed the strongest anti-lipid peroxidation activity, proanthocyanidin A-1 displayed the strongest superoxide scavenging activity, and epicatechin-(4beta--> 6)-epicatechin-(4beta-->8, 2beta-->O--> 7)-catechin had the strongest anti-superoxide formation effect. We conclude that tannins isolated from V. vitis-idaea L. exhibited multiple antioxidant activity, and could be used for the treatment of periodontal disease.

Antioxidants↗

PubMed1999

Tissue polypeptide antigen, carcinoembryonic antigen, carbohydrate antigen, and CA125 levels as tumor markers in squamous cell carcinoma of the head and neck.

Ninety-eight untreated patients with squamous cell carcinoma of the head and neck of different localizations (larynx 36, oral cavity 48, nasal cavity 14) were selected for a study to measure TPA, CEA, CA 19-9, CA125 pre- and post-therapy. Fifty healthy individuals and 42 patients with benign lesions were as normal and disease controls. The positive rates were 22.3%, 27.8%, 5.6% and 0% respectively in TPA, CEA, CA 19-9 and CA125 markers in laryngeal cancer patients. The positive rates of TPA level was higher with significant difference in advanced stage group than in early stage group; conversely, the positive rate of CEA levels were somewhat high in early stages of laryngeal cancer. Meanwhile, the positive rates were 25.0%, 18.8%, 14.6% and 4.2% individually in the same order in oral cancer patients. There was no relationship between the marker levels and progression of the oral cancer. The tumor markers were almost of no use in detecting nasal cancer. It also seemed there was no relationship between the various serum levels and the tumor or nodal burden in laryngeal and oral cancer. Only TPA level decreased significantly after therapy in patients with laryngeal and oral cancer who had originally elevated marker levels. Conclusively, only TPA and CEA markers are of some clinical use in the disease.

Biomarkers, Tumor↗

PubMed1999

Standard oesophageal manometry in healthy adults in Singapore.

Data on oesophageal manometry in normal subjects in the East are limited. The aim of this study was to define standard oesophageal pressure values in a group of healthy adults in Singapore. Standard oesophageal manometry was performed on 26 asymptomatic volunteers (12 males and 14 females, aged 19 to 34 years) using the water-perfused capillary system and stationary pull-through technique. Median (range) lower oesophageal sphincter pressure, distal oesophageal contractile amplitude, distal oesophageal contractile duration and distal oesophageal contractile velocity were 13.6 (8.0 to 32.0) mmHg, 93.0 (41.0 to 143.0) mmHg, 3.8 (3.2 to 5.3) s and 3.6 (2.2 to 4.6) cm/s respectively. They were similar in males and females except for distal oesophageal contractile velocity which was higher in males than females [4.0 (3.1 to 4.6) cm/s versus 3.2 (2.2 to 4.4) cm/s, P < 0.01]. They were also generally in line with published normal values from Western countries. The present study helps to establish standards for normal manometric findings, at least among the young adults, in this part of the world.

Adult↗

PubMed1999

Evaluation of proliferative activity in middle ear cholesteatoma using proliferating cell nuclear antigen.

Middle ear cholesteatoma has a remarkable invasive activity accompanied by destruction of ossicles and temporal bone. Its aggressive growth and high tendency to recur have impact on the postoperative care of the patients. Proliferating cell nuclear antigen (PCNA) is a 36 KDa DNA-delta-polymerase-associated protein whose level of synthesis has been found to correlate directly with rates of cellular proliferation. In this present study, we used ABC (avidin-biotin complex) technique and monoclonal antibody to PCNA to evaluate the expression of PCNA in 37 cases of cholesteatoma epithelium and 21 cases of normal postauricular skin. The rate of PCNA-positive cells in basal, parabasal, and upper layer of cholesteatoma epithelium tissue is 78% (29 cases), 68% (25 cases), and 41% (15 cases). In each layer of the postauricular skin tissue is 71% (15 cases), 67% (14 cases) and 34% (7 cases). No statistical difference of expression of PCNA-positive cells exists between each layer of cholesteatoma epithelium and normal postauricular skin; however, a tendency of higher PCNA-positive cells in cholesteatoma epithelium was observed. Immunohistochemical method of PCNA has the advantages of spatial architecture preservation, the relative simplicity of the methodology and the rapid acquisition of results. Although the etiology and histopathology of the growth pattern and osteolytic activity of cholesteatoma are unclear, information on cell kinetics may assist in cholesteatoma classification and may help predict the risk of recurrence and bone destruction. The results of this report indicate that cholesteatoma has a similar proliferative activity to the normal postauricular skin, and cholesteatoma itself is not a real tumor, despite its clinical behavior, which is similar to neoplastic cells. It is necessary to further study whether the cell kinetic information we obtained from the PCNA immunohistochemical analysis provides a valuable tool in accessing the prognosis of the cholesteatoma.

Adult↗

PubMed1999

Traumatic ossicular chain discontinuity--report of two cases.

In addition to hemotympanum and traumatic eardrum perforation, traumatic ossicular chain discontinuity should also be considered in the differential diagnosis of conductive hearing impairment resulting from head injury. The most common form of these ossicular chain lesions following head injury is incudostapedial joint (I-S joint) separation. We successfully managed two patients with I-S joint separation resulting from head injury through exploratory tympanotomy with ossiculoplasty within the recent 2 years. Both were young females who had sustained head injury resulting from traffic accident with the sequelae of persistent hearing impairment. They both gained significant hearing improvement postoperatively.

Adult↗