Biomedical subjects

K Y Ho

Publications and source records attributed to K Y Ho.

At least 55 records · Page 3Linked to original sources

PubMed1998

Gastroesophageal reflux disease is a common cause of noncardiac chest pain in a country with a low prevalence of reflux esophagitis.

Gastroesophageal reflux disease is believed to be uncommon in the East. This study aimed to determine if such a condition was a significant cause of noncardiac chest pain in Singapore. Eighty consecutive patients with recurrent chest pain, who had cardiac and other obvious causes excluded, underwent esophagogastroduodenoscopy, standard manometry, acid perfusion test, and prolonged ambulatory pH and pressure monitoring. Endoscopic esophagitis, positive acid perfusion tests, pathologic reflux, and positive chest pain-reflux correlation were detected in 7/80 (8.8%), 11/70 (15.7%), 14/61 (23.0%), and 12/25 (48.0%) patients, respectively. Among those with pathologic reflux, endoscopic esophagitis was present in only two (14.3%). Overall, 32 (40%) patients had gastroesophageal reflux disease. Esophageal motility disorder, alone or in association with gastroesophageal reflux disease, was demonstrated in only five (6.3%) patients. Our results confirmed western reports that gastroesophageal reflux disease was a common cause of noncardiac chest pain, whereas motility disorder was an infrequent cause of such pain.

Adult↗

PubMed1998

Symptomatic gastro-oesophageal reflux in pregnancy: a prospective study among Singaporean women.

The present study was undertaken to estimate the prevalence and time course of reflux-type symptoms in Singaporean women and to determine if these symptoms were associated with nausea and vomiting of pregnancy. Consecutive pregnant women in the first trimester of pregnancy were recruited during attendance at an antenatal clinic in a Singapore teaching hospital. Each was interviewed, using a reliable questionnaire detailing demographic characteristics and symptoms, at four time points during the first, second and third trimesters of pregnancy and postpartum period. A total of 35 of 47 women originally enrolled (response rate 74%) completed the study. Heartburn alone, acid regurgitation alone and both heartburn and acid regurgitation were reported by 5.7, 17.1 and 17.1% of the subjects, respectively. Subjects who had these symptoms were more likely to suffer daily nausea and/or vomiting (78.6%) than those who did not (33.3%, P<0.05). In the majority of subjects, heartburn and/or acid regurgitation began in the first trimester (78.6%) and disappeared during the second trimester (71.4%). Nausea alone and in combination with vomiting similarly came on in the first trimester (100%) and subsided by the second trimester (85.7%) in the majority of the subjects studied. The reported prevalence of heartburn and/or acid regurgitation among Western pregnant women were 48-96% and 62%, respectively. Our data, therefore, showed that reflux-type symptoms were less common in Singaporean pregnant women. Reflux-type symptoms were related to nausea and vomiting, both in frequency and time pattern of onset and disappearance of symptoms. The association suggested either a common mechanism or a cause and effect relationship.

Adult↗

PubMed1998

The effect of test duration on the sensitivity and specificity of ultra-rapid urease test for the detection of Helicobacter pylori infection.

BACKGROUND: 'Home made' ultra-rapid urease tests are used extensively in the Asia Pacific region. Data on the reliability of these 'home made' tests are limited. AIMS: To evaluate the effect of test duration on the sensitivity and specificity of a self-prepared biopsy urease test for the detection of Helicobacter pylori. METHODS: Using histology as the 'gold standard', the effect of test duration on the sensitivity and specificity of a self prepared urease test for the detection of H. pylori was evaluated in 411 consecutive patients undergoing upper gastrointestinal endoscopy. RESULTS: Histology was positive for H. pylori in 217 of the 411 patients (52.8%). Within 24 hours of retrieving the specimen, 189 (87.1%) of the histology positives and 174 (89.7%) of the histology negatives were correctly identified by the urease test. Of the H. pylori positives, 72.0%, 81.0%, 89.9% and 100% were detected by the urease test within one minute, five minutes, three hours and 24 hours respectively. Thus, sensitivities of the urease test at one minute, five minutes, three hours and 24 hours were 62.7%, 70.5%, 78.3% and 87.1% respectively. Corresponding figures for the specificity were 93.8%, 93.3%, 92.3% and 89.7% respectively. Using a receiver-operating characteristic curve, an optimal combination of sensitivity and specificity was obtained when the urease test was read at 24 hours. CONCLUSIONS: While the biopsy urease test was positive in most cases within a minute, better results could be obtained if the test continued to be read over a 24 hour period.

Adolescent↗

PubMed1998

Prevalence of gastrointestinal symptoms in a multiracial Asian population, with particular reference to reflux-type symptoms.

OBJECTIVE: Data on the epidemiology of chronic gastrointestinal symptoms in the East are limited. The aims of this study were to estimate the prevalence of chronic gastrointestinal symptoms in Singapore and to determine whether ethnic differences in the prevalence of these symptoms exist. METHODS: A cross-sectional survey, using a reliable and valid questionnaire, was carried out in a race-stratified random sample of residents aged 21-95 yr (mean+/-SD, 40+/-1 yr) in a Singaporean town; 93% responded (n=696). RESULTS: The ethnic-adjusted prevalence of chronic abdominal pain, frequent dyspepsia, irritable bowel syndrome, chronic constipation, chronic diarrhea, and frequent reflux were 5.7% (95% confidence interval [CI], 3.3-8.1), 7.9% (95% CI, 5.0-10.8), 2.3% (95% CI, 0.8-3.9), 3.9% (95% CI, 1.9-5.9), 4.5% (95% CI, 2.3-6.7), and 1.6% (95% CI, 0.6-2.6), respectively. There were no ethnic differences in the prevalence of any of these symptom categories except for reflux-type symptoms, which were more common among Indians (7.5%; 95% CI, 4.4-11.7) than Chinese (0.8%; 95% CI, 0.1-3.0) or Malays (3.0%; 95% CI, 1.26.1). CONCLUSION: The prevalence of all types of chronic gastrointestinal symptoms in the general population of Singapore was low compared with those in the West. Chronic gastrointestinal symptoms were equally prevalent in the three major ethnic groups except for reflux-type symptoms, which were more common among Indians than Chinese or Malays.

Abdominal Pain↗

PubMed1998

Non-cardiac, non-oesophageal chest pain: the relevance of psychological factors.

BACKGROUND: No cause has been determined for chest pain that is neither cardiac nor oesophageal in origin. AIMS: To compare the prevalence of life-time psychiatric disorders and current psychological distress in three consecutive series of patients with chronic chest or abdominal pain. PATIENTS: Thirty nine patients with non-cardiac chest pain and no abnormality on oesophagogastroduodenoscopy, oesophageal manometry, and 24 hour pH monitoring; 22 patients with non-cardiac chest pain having endoscopic abnormality, oesophageal dysmotility, and/or pathological reflux; and 36 patients with biliary colic. METHODS: The Diagnostic Interview Schedule and the 28 item General Health Questionnaire were administered to all patients. RESULTS: Patients with non-cardiac chest pain and no upper gastrointestinal disease had a higher proportion of panic disorder (15%), obsessive-compulsive disorder (21%), and major depressive episodes (28%) than patients with gallstone disease (0%, p < 0.02; 3%, p < 0.02; and 8%, p < 0.05, respectively). In contrast, there were no differences between patients with non-cardiac chest pain and upper gastrointestinal disease and patients with gallstone disease in any of the DSM-111 defined lifetime psychiatric diagnoses. Using the General Health Questionnaire, 49% of patients with non-cardiac chest pain without upper gastrointestinal disease scored above the cut off point (that is, more than 4), which was considered indicative of non-psychotic psychiatric disturbance, whereas only 14% of patients with gallstones did so (p < 0.005). The proportions of such cases were however similar between patients with non-cardiac chest pain and upper gastrointestinal disease (27%) and patients with gallstones. CONCLUSIONS: Psychological factors may play a role in the pathogenesis of chest pain that is neither cardiac nor oesophagogastric in origin.

Adult↗

PubMed1998

Peripheral vascular tree stenoses: detection with subtracted and nonsubtracted MR angiography.

PURPOSE: To compare subtracted and nonsubtracted gadolinium-enhanced magnetic resonance (MR) angiography and cardiac-synchronized time-of-flight MR angiography for help in detecting pelvic-region stenoses. MATERIALS AND METHODS: Twenty-eight patients with intermittent claudication underwent MR angiography with a 1.5-T system; two-dimensional cardiac-synchronized time-of-flight MR angiograms and three-dimensional MR angiograms (without and with gadolinium enhancement) were obtained. Subtracted images were obtained by subtracting unenhanced data from enhanced data of identical volumes, and maximum intensity projection images were constructed, which two observers independently evaluated in blinded fashion, with conventional angiographic results as the reference standard. RESULTS: Sensitivity and specificity for grading of hemodynamically significant stenoses (> or = 50% lumen reduction) on subtracted MR angiograms were 94% and 93%, respectively. Sensitivity of subtracted images was significantly higher compared with that of time-of-flight images (P < .05) but not with that of nonsubtracted images. Contrast-to-noise ratio on subtracted images was significantly higher compared with that on nonsubtracted images (P < .05) but not with that on time-of-flight images. There was good correlation between stenosis length measurements on gadolinium-enhanced MR angiograms and those on conventional angiograms. CONCLUSION: Subtracted MR angiography is superior to cardiac-synchronized time-of-flight MR angiography for imaging of iliac and upper femoral arteries and provides higher contrast-to-noise ratio, fewer artifacts, and easier image interpretability than nonsubtracted MR angiography.

Angiography↗

PubMed1998

Peripheral vascular tree stenoses: evaluation with moving-bed infusion-tracking MR angiography.

PURPOSE: To evaluate a magnetic resonance (MR) angiographic technique for imaging of the peripheral arteries with gadolinium enhancement. MATERIALS AND METHODS: Moving-bed infusion-tracking MR angiograms were obtained in 15 healthy volunteers and in 28 patients with intermittent claudication before and during slow infusion of contrast material. Lower- and upper-leg and pelvic regions were imaged. Unenhanced images were subtracted from gadolinium-enhanced images, and maximum intensity projection images were generated. Image quality was evaluated subjectively and objectively, and maximum intensity projection images were compared with conventional angiograms, which served as the standard of reference. RESULTS: Moving-bed infusion-tracking MR angiography proved to be a robust technique, and image quality on maximum intensity projection images was comparable with that on conventional angiograms. Sensitivity and specificity for grading hemodynamically significant stenoses were 93% and 98%, respectively, with excellent interobserver agreement. CONCLUSION: Moving-bed infusion-tracking MR angiography can be used to image all peripheral arteries in 4 minutes by using a small amount of contrast material and a conventional 1.5-T MR imager.

Constriction, Pathologic↗

PubMed1998

The effect of octreotide on breathing and the ventilatory response to CO2 in conscious dogs.

It has been reported that injection of somatostatin into the brain-stem will lead to apnoea in animals. The aim of this study was to determine whether peripheral administration of octreotide, an analogue of somatostatin, could influence the control of breathing. We measured the tidal volume, respiratory rate and ventilatory response to CO2, before and after the intravenous injection of two dose levels of octreotide (0.1 mg and 0.5 mg) or saline in four conscious adult dogs. Injection of octreotide altered the breathing pattern with a mean decrease in the respiratory frequency of 23% (p<0.05) and an increase in the tidal volume by 16% (p<0.05), resulting in no net change in ventilation. The normal value of the ventilatory response to CO2 ranged between 1.0-3.2 L x min(-1) x mmHg(-1), with a minor variance within each dog but a significant difference amongst the four dogs (p<0.05). No significant change in the ventilatory response to CO2 was observed after octreotide. We conclude that intravenous octreotide alters the pattern of breathing but preserves minute ventilation; peripheral administration of octreotide does not influence the ventilatory response to CO2.

Animals↗

PubMed1998

Management of labyrinthine fistula in middle ear cholesteatoma.

Labyrinthine fistula is a complication of chronic otitis media with cholesteatoma. Canal wall down tympanoplasty with partial mastoid cavity obliteration and complete removal of cholesteatoma matrix was adopted in five cases of labyrinthine fistula. The operation resulted in elimination of vertigo. Sensory hearing has been saved in two cases. Air conduction hearing improved in one case. In three cases whose air conduction deteriorated post-operatively, bone conduction worsened in two cases and remained unchanged in one case (Tympanoplasty type 0 was performed in the other one case.) During the follow-up period, otorrhea improved in all cases and there was no evidence of recurrence of cholesteatoma. If the hearing of the other ear is acceptable, we suggest one-stage canal wall down tympanoplasty with complete removal of cholesteatoma matrix and partial mastoid cavity obliteration. It provides low recurrence rate of cholesteatoma and there is no need of re-operation.

Adolescent↗

PubMed1998

Sensorineural hearing loss in MELAS syndrome--case report.

A mitochondrial tRNA mutation at nucleotide 3,243 is known to be found in most patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes). We report a 30 year-old female patient of MELAS, diagnosed 5 years ago, who presented herself to our ENT outpatient department because of her bilateral tinnitus and progressive hearing impairment since 4 years ago. Two sequential pure tone audiograms showed bilateral symmetrical progressive sensorineural hearing loss, especially in the high frequency area in 1993 and 1996. The pure tone average was R-45 dB, L-47 dB in 1993 and R-62 dB, L-67 dB in 1996. Hearing loss is an important feature in MELAS syndrome and reported to be seen in about 30% of patients. It is often the first clinical symptom, too. In any case, mitochondrial cytopathies need to be considered by the otologist in forming a diagnosis of sensorineural hearing loss (SNHL), particularly in cases, which present adult-onset progressive hearing loss and neurologic symptoms before 50 years of age.

Adult↗

PubMed1998

Characterization of clinical isolates of Helicobacter pylori in Singapore.

Of the 69 Helicobacter pylori isolates analysed, 31 strains (45%) showed resistance to metronidazole, one strain (1.4%) was resistant to amoxicillin while two strains (2.9%) were resistant to clarithromycin. It was found that metronidazole resistance rates increased in Singapore from 20% to 62% between late 1995 and early 1997. By biotyping using API ZYM, a total of 80% (55/69) strains were characterized as biotype II, while the remaining 20% (14/69) strains belonged to biotype III. Interestingly, 71% (10/14) of biotype III were resistant to metronidazole compared with 38% (21/55) of biotype II. DNA profiles generated by random amplified polymorphic DNA from 69 isolates showed highly diversified DNA fingerprints allowing effective discrimination among strains. Of the 60 H. pylori isolates from peptic ulcer patients, it was found that cagA and vacA occurred in 80% (48/60) and 82% (49/60) isolates, respectively.

Amoxicillin↗

PubMed1998

Age and the prognosis of tympanoplasty type I.

The purpose of this study is to evaluate the influence of the age factor on the prognosis for tympanoplasty type I. One hundred subjects (41 males, 59 females, 16-65 years old, mean age 37.9 years old) who accepted tympanoplasty type I during a four-year period were reviewed. The success rate of the surgery was analyzed using the three criteria suggested by the Japan Clinical Otology Committee. In addition, linear regression was used to analyze the correlations between age and pre-operative hearing, post-operative hearing and hearing gain. Using the proportion of patients with a postoperative hearing threshold within 40 dB as the criterion, the 16-25 year-old group had the best results (80%) and the 56-65 year-old group had the worst results (66.7%). Using hearing gain exceeding 15 dB as the criterion, the best result was for the 36-45 year-old group (60.9%), and the worst result was for the 56-65 year-old group (26.7%). Using post-operative air-bone gap within 20 dB as the criterion, the best result was for the 16-25 year-old group (70%), and the worst result was for the 56-65 year-old group (40%). The best total success rate was for the 16-25 year-old group (80%) and the worst was for the 56-65 year-old group (66.7%). The total average success rate was 74%. Linear regression analysis showed that the postoperative hearing thresholds increased significantly with advancing age. But there was no statistically significant difference in hearing gain between the various age groups and the preoperative hearing thresholds also increased with advancing age. In conclusion, although tympanoplasty type I offered the patients a similar hearing gain among the different age groups, from the point of view of social function, it offered younger people a better chance of social hearing than the elderly and a higher surgical success rate. The poor postoperative hearing of the elderly was a result of their poor preoperative hearing condition.

Adolescent↗

PubMed1998

Evaluating the sensation of nasal obstruction with acoustic rhinometry and rhinomanometry.

The relationships among subjective sensation of nasal obstruction, data of rhinomanometry and acoustic rhinometry between individuals or for each individual were explored. Thirty-nine subjects with nasal obstruction problems were examined using the visual analogue scale, nasal airflow resistance (NAR), nasal minimal cross-sectional area (MCA), and nasal cavity volume (NCV). No significant correlation was found between the sensation of unilateral or bilateral nasal obstruction to NAR, MCA, or NCV. Strong correlations between MCA and NAR, and NCV and NAR were noted in this study. Another 10 healthy volunteers were investigated and correlation was studied on each individual level. Strong correlations within subject were found more commonly in persons with short-term follow-up than with the long-term follow-up group. In the present study, rhinomanometry results were compatible with acoustic rhinometry results. However describing the sensation of nasal patency with only rhinomanometric or acoustic rhinometric measurements seems still inadequate.

Adult↗

PubMed1998

The probability of diagnosis of nasopharyngeal carcinoma in patients with only adult-onset otitis media with effusion.

This study tried to assess the probability of nasopharyngeal carcinoma (NPC) being present in adults with only otitis media with effusion (OME) and evaluate the necessity of nasopharyngeal biopsy in Taiwanese adults with only OME. The clinical features of patients with known OME were analyzed and the incidence of nasopharyngeal carcinoma in adults with only OME was assessed. The clinical features of 36 adults with OME but without other symptoms and signs suggestive of NPC who presented to the Kaohsiung Medical College Hospital Department of Otorhinolaryngology between December 1995 and February 1997 were analyzed. Two of these patients had biopsy-proven non-keratinizing carcinomas. OME was caused by upper respiratory infection in 8 patients (22.2%), chronic paranasal sinusitis in 5 (13.9%), allergic rhinitis in 5 (13.9%), NPC in 2 (5.6%), other etiologies in 5 (13.9%) and by unknown etiologies in 11 (30.5%). The incidence of NPC in adults with OME but no other symptoms and signs suggestive of NPC was 5.6% (2 out of 36 patients). It was higher than other reports because NPC has a high prevalence in Taiwan. Therefore, biopsy of the post-nasal space in adults with only OME when NPC is strongly suspected is necessary for the early diagnosis of NPC in Taiwan. We conclude that Taiwanese adults with only OME for which the cause is unclear should be subjected to an examination and biopsy of the nasopharynx to exclude NPC.

Adult↗

PubMed1998

Bone regeneration in advanced periodontitis lesions after a single episode of root planing--case report with ten-years of follow-up.

This report describes a significant bone regeneration in a mandibular molar with advancing long-standing periodontal disease (defect extending to apex and into furcation) following a single episode of scaling and root planing. A 52-year-old female suffered from generalized moderate periodontitis for two years. An acute periodontal abscess with a 12 mm probing depth around the right mandibular first molar was noted. After incision and drainage, thorough scaling and root planing was performed under local anaesthesia. Three months later, radiographic examination showed complete bone regeneration with formation of a distinct lamina dura. It was concluded that favorable clinical and radiographic results could be obtained after a single episode of thorough subgingival root planing combined with excellent oral hygiene maintenance.

Bone Regeneration↗

PubMed1998

Prolonged ambulatory oesophageal pH and pressure recording in healthy adults in Singapore.

BACKGROUND/AIM OF STUDY: Data on prolonged ambulatory oesophageal pH and pressure monitoring in normal subjects in the East are limited. This study aimed to define the normal characteristics of ambulatory oesophageal pH and motility among healthy adults in Singapore. METHOD: Prolonged ambulatory oesophageal pH and pressure recording was performed on 10 healthy volunteers using a one-channel pH probe, a two channel pressure probe, a portable digital data recorder and a computerised data analysis system. The median (range) number of episodes with pH < 4 and the percentage of total time with pH < 4 were 24% (4%-56%) and 3.0% (0.2%-4.0%) respectively. They were greater in the upright than supine positions. RESULTS: The median percentages of peristaltic and simultaneous contractions were 65.8%-80.5% and 10.6%-12.7% respectively. The frequency, amplitude and duration of peristaltic contractions were greater during mealtimes than between meals in the upright position. CONCLUSION: This study provides the first data on prolonged ambulatory oesophageal pH and manometry in healthy Singaporean adults.

Adult↗

PubMed1997

Inhibitory effects of jasmine green tea epicatechin isomers on free radical-induced lysis of red blood cells.

Jasmine green tea is an excellent source of natural polyphenol antioxidants including mainly (-) epicatechin (EC), (-) epicatechin gallate (ECG), (-) epigallocatechin (EGC) and (-) epigallocatechin gallate (EGCG). The present study was to test our hypothesis that ingestion of jasmine tea would protect red blood cell (RBC) membrane from free radical-induced oxidation if jasmine tea epicatechin isomers could be absorbed and circulated in blood. When incubated with RBC suspension, all four epicatechin isomers purified from jasmine tea exhibited a strong protection for RBC membrane to hemolysis induced by 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH), an azo free radical initiator. The inhibitory effect was dose-dependent at the concentrations of 2.5 microM to 40 microM. The fatty acid analysis revealed that all four epicatechin isomers significantly prevented loss of arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) in RBC incubated under the same conditions. Although the in vitro antioxidative activity of EGCG and ECG was more effective than EGC and EC, the latter two isomers were more important in vivo in scavenging free radicals. This was because only EGC and EC instead of EGCG and ECG were circulating in blood stream after a gavage-dose of 100 mg jasmine tea GTP mixture. In fact, ingestion of jasmine tea GTP extracts was associated with a significant decrease in susceptibility of RBC to hemolysis in rats.

Amidines↗

PubMed1997

Racial differences in Helicobacter pylori seroprevalence in Singapore: correlation with differences in peptic ulcer frequency.

The aim of this study was to determine, first, whether racial differences exist in the seroprevalence of Helicobacter pylori infection in Singapore, and second, whether these differences correlate with racial differences in peptic ulcer frequency. A commercial serological test for immunoglobulin (Ig)G antibody to H. pylori which was 90% sensitive and 83% specific in our population was used to screen 403 adult blood donors of Chinese, Malay and Indian origin, aged between 15-60 years. Serum specimens from 84 paediatric patients admitted to the Paediatrics Department, National University of Singapore, with non-gastroenterological illnesses were also tested. In all three races, seroprevalence of H. pylori increased with age. Indians have the highest prevalence of infection followed by Chinese and Malays. Peptic ulcer prevalences are known to be highest in Chinese, followed by Indians and Malays. The Malays have the lowest prevalence of H. pylori and peptic ulcer among the three races in Singapore. Indians have a higher prevalence of H. pylori antibodies but a lower frequency of peptic ulcer than the Chinese. Racial differences in peptic ulcer frequency between Chinese and Indians are not explained by the prevalence of H. pylori infection; other environmental or genetic factors may be involved.

Adolescent↗