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Biomedical subjects

L Y Wong

Publications and source records attributed to L Y Wong.

At least 19 recordsLinked to original sources
PubMed2002

Clinicopathologic significance of bcl-2 expression in the surgical treatment of oral tongue carcinoma.

AIM: There is still controversy on the incidence of positive expression of bcl-2 and its prognostic significance for oral tongue carcinoma patients who are treated by surgery. The present study aims at resolving the controversy on the clinicopathologic significance of bcl-2 in a well selected group of patients who satisfy the recruitment criteria: (1) oral tongue carcinoma, (2) squamous cell carcinoma, (3) primary surgical treatment. METHOD: Bcl-2 expression was studied by immunohistochemistry on glossectomy specimens of 73 patients. The expression of bcl-2 was correlated with clinicopathologic data. RESULTS: Of the 73 tumours, 11% had positive expression of bcl-2. Bcl-2 expression was not significantly correlated with tumour grade, stage, nodal metastasis and survival. CONCLUSION: Bcl-2 expression played a minor role in oral tongue carcinoma. It had no significant correlation with tumour grade, stage and nodal metastasis. It also had no prognostic value on survival for patients who were treated by primary surgery.

Adolescent↗
PubMed2001

Impact of folic acid fortification of the US food supply on the occurrence of neural tube defects.

CONTEXT: Daily consumption of 400 microg of folic acid before conception and during early pregnancy dramatically reduces the occurrence of neural tube defects (NTDs). Before food fortification, however, only an estimated 29% of US reproductive-aged women were taking a supplement containing 400 microg of folic acid daily. The US Food and Drug Administration authorized addition of folic acid to enriched grain products in March 1996, with compliance mandatory by January 1998. OBJECTIVE: To evaluate the impact of food fortification with folic acid on NTD birth prevalence. DESIGN, SETTING, AND POPULATION: National study of birth certificate data for live births to women in 45 US states and Washington, DC, between January 1990 and December 1999. MAIN OUTCOME MEASURE: Birth certificate reports of spina bifida and anencephaly before fortification (October 1995 through December 1996) compared with after mandatory fortification (October 1998 through December 1999). RESULTS: The birth prevalence of NTDs reported on birth certificates decreased from 37.8 per 100 000 live births before fortification to 30.5 per 100 000 live births conceived after mandatory folic acid fortification, representing a 19% decline (prevalence ratio [PR], 0.81; 95% confidence interval [CI], 0.75-0.87). During the same period, NTD birth prevalence declined from 53.4 per 100 000 to 46.5 per 100 000 (PR, 0.87; 95% CI, 0.64-1.18) for women who received only third-trimester or no prenatal care. CONCLUSIONS: A 19% reduction in NTD birth prevalence occurred following folic acid fortification of the US food supply. However, factors other than fortification may have contributed to this decline.

Folic Acid↗
PubMed2001

Survival of infants with spina bifida: a population study, 1979-94.

This study aimed to investigate the survival of infants born with spina bifida between 1979 and 1994 from the population-based Metropolitan Atlanta Congenital Defects Program (MACDP) and to identify clinical and demographic factors associated with survival. Survival status was obtained from MACDP records and the National Death Index. Survival rates were calculated using the Kaplan-Meier method. Risk factors potentially associated with survival were examined by the log-rank test. We assessed the independent effect of risk factors using the Cox proportional hazards model. Overall, 78.4% of children with spina bifida survived during the study period. Of the 235 infants born with spina bifida, 87.2% survived the first year of life. Survival to age 1 for the 1979-83, 1984-88 and 1989-94 birth cohorts was 82.7%, 88.5% and 91.0% respectively. In multivariable analysis, factors associated with increased mortality were low birthweight (<2500 g) (vs. > or =2500g, relative risk (RR) 2.3 [95% CI 1.1, 4.9]) and high lesions (vs. low lesions, RR 3.4 [95% CI 1.6, 7.1]). This study suggests a continuous improvement in survival among children born with spina bifida in Atlanta. Demographic and clinical factors are associated with length of survival. This information is useful for both clinicians and families who need to plan for the long-term care of these children.

Birth Weight↗
PubMed2001

Epidemiology of headache in Hong Kong primary-level schoolchildren: questionnaire study.

OBJECTIVE: To collect and analyse epidemiological data on childhood headache in the Hong Kong community. DESIGN: Questionnaire study. SETTING: Three primary schools, Hong Kong. PARTICIPANTS: Two thousand, one hundred and twenty pupils from 2156 replied to the questionnaire survey. One hundred and twenty-four pupils who were identified to have suspected recurrent headache were invited to a follow-up medical consultation. MAIN OUTCOME MEASURES: Age-groups and prevalence of tension-type and migraine headache, using the diagnostic criteria of the International Headache Society. RESULTS: The overall prevalence of headache in the 2120 respondents was 2.8%. The prevalence of tension-type headache, migraine, probable migraine, and unclassified headache were 1.2%, 0.5%, 0.7%, and 0.5%, respectively. The age-specific prevalence of headache from the age of 6 to 13 years showed a steadily increasing trend from childhood to the early teens. CONCLUSION: Headache is a common complaint for children, although it may be underrecognised. Further study will be beneficial for providing better management of headache in this population.

Adolescent↗
PubMed2000

Visual field plasticity in a female with right occipital cortical dysplasia.

Brain plasticity refers to its ability to recover after damage. Visual field plasticity is not well recognized. We report a 12-year-old female who first presented with recurrent seizures and was subsequently found to have a large, right occipital cortical dysplasia on magnetic resonance imaging. Her visual field by Goldmann perimetry was totally normal. Visual-evoked potential studies revealed the left hemifield P100 response was detected maximally at the right temporal and parietal regions. A weak but reproducible right hemifield P100 response was located at the right medial skull base. Functional magnetic resonance imaging with flashlight stimulation revealed cerebral activity mainly at the right posterior temporal and parietal lobes and left occipital lobe. These studies suggested that the left hemifield function was located at the right posterior temporal and parietal lobes. The left occipital lobe may also have been reorganized, with a P100 vector pointing out from its inferiomedial base. We reviewed other related reported cases. We believe that visual-evoked potential studies and visual functional magnetic resonance imaging should be performed more liberally for recognition of visual field plasticity.

Brain Mapping↗
PubMed2000

General method for HPLC purification and sequencing of selected dsDNA gene fragments from complex PCRs generated during gene expression profiling.

Gene expression profiling using an AFLP-based technique generates a large number of gene fragments that require identification by sequencing. The DNA fragments vary in length from about 50-500 bp. Ion-pair reversed-phase HPLC can be used to purify selected double-stranded DNA fragments that represent differentially expressed genes. The gene fragments are sequenced directly after vacuum drying of the collected HPLC fractions.

Animals↗
PubMed1999

Prevention of neural-tube defects with folic acid in China. China-U.S. Collaborative Project for Neural Tube Defect Prevention.

BACKGROUND AND METHODS: Periconceptional administration of folic acid can reduce a woman's risk of having a fetus or infant with a neural-tube defect. As part of a public health campaign conducted from 1993 to 1995 in an area of China with high rates of neural-tube defects (the northern region) and one with low rates (the southern region), we evaluated the outcomes of pregnancy in women who were asked to take a pill containing 400 microg of folic acid alone daily from the time of their premarital examination until the end of their first trimester of pregnancy. RESULTS: Among the fetuses or infants of 130,142 women who took folic acid at any time before or during pregnancy and 117,689 women who had not taken folic acid, we identified 102 and 173, respectively, with neural-tube defects. Among the fetuses or infants of women who registered before their last menstrual period and who did not take any folic acid, the rates of neural-tube defects were 4.8 per 1000 pregnancies of at least 20 weeks' gestation in the northern region and 1.0 per 1000 in the southern region. Among the fetuses or infants of the women with periconceptional use of folic acid, the rates were 1.0 per 1000 in the northern region and 0.6 per 1000 in the southern region. The greatest reduction in risk occurred among the fetuses or infants of a subgroup of women in the northern region with periconceptional use who took folic acid pills more than 80 percent of the time (reduction in risk, 85 percent as compared with the fetuses or infants of women who registered before their last menstrual period and who took no folic acid; 95 percent confidence interval, 62 to 94 percent) [corrected]. In the southern region the reduction in risk among the fetuses or infants of women with periconceptional use of folic acid was also significant (reduction in risk, 41 percent; 95 percent confidence interval, 3 to 64 percent). CONCLUSIONS: Periconceptional intake of 400 microg of folic acid daily can reduce the risk of neural-tube defects in areas with high rates of these defects and in areas with low rates.

Adult↗
PubMed1999

Nausea during pregnancy and congenital heart defects: a population-based case-control study.

The authors investigated the possible association between a mother's nausea during pregnancy and her child's risk for a congenital heart defect using data from the population-based Atlanta Birth Defects Case-Control Study conducted in 1982-1983. Case infants (n = 998) had nonsyndromic congenital heart defects and control infants (n = 3,029) had no congenital defects. Nausea during pregnancy (NP) was graded in eight levels of "severity" based on its onset, frequency, and duration. Level 1, the most severe NP, was associated with a lower risk for a congenital heart defect in the child (odds ratio (OR) = 0.81, 95% confidence interval (CI) 0.67-0.99) compared with no nausea. The lower risk tended to disappear with less severe levels of nausea, and the trend was statistically significant. Overall, early NP (levels 1 to 4 combined) with use of antinausea medication, particularly Bendectin (doxylamine, dicyclomine (dropped from the formulation in 1976), pyridoxine (vitamin B6)), was associated with a lower risk for congenital heart defects compared with: 1) absence of nausea (OR = 0.67, 95% CI 0.50-0.92), and 2) nausea without medication use (OR = 0.70, 95% CI 0.50-0.94). The results suggest that pregnancy hormones and factors or, alternatively, a component of Bendectin (most probably pyridoxine) may be important for normal heart development. These findings outline potential areas for future research on and prevention of congenital heart defects.

Adolescent↗
PubMed1996

From maximum surgical blood ordering schedule to unlimited computer crossmatching: evolution of blood transfusion for surgical patients at a tertiary hospital in Hong Kong.

The maximum surgical blood ordering schedule (MSBOS) was developed to permit efficient use of blood stocks and reduce blood wastage due to outdating. Success of the MSBOS required full cooperation between surgeons, anaesthetists, blood bankers and house officers. However, clinical staff sometimes disregarded the system or distrusted the ability of the laboratory to provide blood in an emergency. This led to frustration and wastage of laboratory staff effort. We developed a computer crossmatch system that could overcome the shortcomings of the MSBOS. The advantages of this system are reported.

Antibodies↗
PubMed1993

Cranial computed tomography in children with acute lymphoblastic leukemia after prophylactic treatment with cranial radiation therapy and intrathecal methotrexate.

BACKGROUND AND METHODS: Thirty-one children with acute lymphoblastic leukemia (ALL) who had received cranial radiation therapy (CrRT) and five concomitant doses of intrathecal methotrexate (IT MTX) for central nervous system prophylaxis (CNSP) and who had an event-free survival exceeding 5 years had cranial computed tomography (Cr CT) examination. The fractional dose for 21 of them was 1.5 Gy. The interval between the completion of CNSP and the time of Cr CT ranged from 5 to 8.5 years, with a median of 5 years 2 months. RESULTS: Unlike the previous reports in the literature that 9-77% of children with ALL who had received Cr RT 18 Gy and IT MTX as CNSP had CT scan abnormalities, in this study no patient had CT scan abnormalities. CONCLUSIONS: Our results might be attributable to the fractional dose of Cr RT being adequate, the IT chemotherapy being suitable, and the systemic chemotherapy not being intensive.

Brain↗
PubMed1991

Effect of blood transfusion on acid base, glucose and electrolyte status in very low birth weight infants.

The effect of citrate phosphate dextrose (CPD) blood transfusion on the acid base, glucose and electrolyte status of VLBW infants was studied in infants aged 1-7, 8-20 and greater than 20 days; a 4th group composed of infants greater than 20 days subjected to a second transfusion was also studied. All the infants remained clinically well during and after the transfusion. Only the infants in the group 1-7 days experienced a significant fall in ionic Ca and PO2. No significant change in all the other parameters studied was observed. In the other groups of infants studied, the changes observed were not significant, and became less with increasing age and repeat transfusion. VLBW infants apparently tolerate CPD blood transfusion well.

Acid-Base Equilibrium↗
PubMed1991

Renal osteodystrophy.

The term "renal osteodystrophy" is used to include skeletal disorders of patients with chronic renal failure: osteitis fibrosa, osteomalacia, osteosclerosis, osteoporosis and the frequently associated extraskeletal calcifications. It is the chronic glomerular disease with phosphate retention and resultant hyperphosphatemia on one hand and deficient 1,25 (OH)2 D3 and resultant hypocalcemia on the other to induce secondary hyperparathyroidism. The three most common causes of chronic renal failure in our patients are chronic glomerulonephritis, diabetic nephropathy, hypertensive nephropathy in decreasing frequency, polycystic renal disease occurs in five patients. Other miscellaneous causes include nephrotic syndrome, chronic pyelonephritis, systemic lupus erythematosus, periarteritis nodosa, interstitial nephritis and renal stones. The bone changes are similar in primary and secondary hyperparathyroidism and the incidence of brown tumor is about 3% in the former and 1.5 to 1.7% in the latter. We present one among the 94 dialyzed patients who has long-standing severe chronic renal failure from polycystic kidney disease and develops brown tumor in the mid ulna after 7 years on maintenance hemodialysis. The incidence of brown tumor in our series is about 1.1%. Because of increased longevity of the dialyzed patients, brown tumor from secondary hyperparathyroidism is now more commonly observed. Hyperphosphatemia with serum calcium-phosphate products exceeding plasma solubility of 60 to 75 mg/dl may induce soft tissue and vascular calcification. This explains the much higher incidence of soft tissue calcification in secondary than primary hyperparathyroidism; two of our patients with generalized Monckeberg's type arterial calcification and multiple periarticular calcifications in five patients have been observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Parosteal osteosarcoma: a case report.

Parosteal osteosarcoma is a low-grade malignant tumor arising from the periosteum. It involves mainly adults of third to sixth decades and the favorite site is the posterior aspect of distal femoral metaphysis. Microscopically, it is composed of woven to lamellar bone trabeculae within spindle cell stroma. We present a case of parosteal osteosarcoma that has very well-formed lamellar bone trabeculae and fat marrow under microscopic examination. Without the help of radiologic study, it is impossible to make the diagnosis of parosteal osteosarcoma.

Bone Neoplasms↗
PubMed1990

Detection of tumour antigens in sera of patients with hepatocellular carcinoma using monoclonal antibodies.

A total of 70 serum samples taken from patients with hepatocellular carcinoma (HCC), acute viral hepatitis and cirrhosis and normal individuals were tested in a binding inhibition immunofluorescence assay using 5 mouse monoclonal antibodies (2G9, 3H11, 3H12, 1C7, 3H5) specific for hepatoma cells. Seven out of the 30 HCC sera (23.3%) inhibited the binding of one of these antibodies, 3H11. This detection of antigen 3H11 or antigens of similar structure in HCC sera was significantly more frequent than in control sera (1/40 = 2.5%) (Fisher's exact test, p = 0.009; df = 1, relative risk calculated by the odds ratio in a 2 x 2 table = 12.0). The presence of this antigen was unrelated to the hepatitis B surface antigen and alphafetoprotein status. Thus it would be of value particularly for the detection of hepatitis B negative or alphafetoprotein negative liver cancers.

Acute Disease↗
PubMed1988

Altered fibrinolysis in DVT: influence of site of sampling.

Alteration of the fibrinolytic system is considered to be important in the development of deep venous thrombosis (DVT). Using specific assays for tissue plasminogen activator (t-PA) activity, t-PA inhibitor (PAI) and t-PA antigen, we measured these activities in 16 women who developed DVT during their pregnancies. A group of 24 healthy females of comparable age was studied as controls. PAI was increased in 87% of these patients compared to the healthy controls. In some of these patients a defect in release of t-PA from vascular endothelium was found as well. The site at which blood was sampled for analysis appeared to be an important criterion in the ex vivo assessment of functional t-PA reserve and PAI levels, though relatively less so for the latter measurement. The unaffected lower limbs, relative to the unaffected upper limbs, showed an increase in PAI and a demonstrable decrease in t-PA release, both representing increased risk factors for rethrombosis. The affected lower limbs showed similar but more accentuated changes in these parameters.

Adult↗
PubMed1988

The prevalence of hepatitis B virus markers in dental personnel in Singapore.

A seroepidemiological survey of the prevalence of hepatitis B virus (HBV) markers was conducted in a group of 693 dental personnel in Singapore where HBV infection is endemic. The overall prevalence of HBsAg (4.5%) and anti-HBc (29%) was no higher than that in the general population. However, dentists had a significantly higher HBsAg prevalence (11.4%) compared with that in the general population (4.2%) (P less than 0.01) and of other categories of dental personnel (3.1%) (P less than 0.001). Similarly, the anti-HBc prevalence of the dentists (45.6%) was significantly higher than that of the general population (29.7%) (P less than 0.01) and of other categories of dental personnel (25.7%) (P less than 0.0001). It appears that dentists in the endemic area have a definite occupational risk of acquiring HBV infection.

Dental Staff↗
PubMed1988

Effect of recombinant gamma interferon on hepatocellular carcinoma cell lines.

The effects of recombinant gamma interferon (rIFN-gamma) were tested on 4 different hepatocellular carcinoma (HCC) cell lines PLC/PRF/5, HepG2, Hep3B and SK-Hep1. Exposure of these HCC cells to 100/ml of rIFN-gamma induced high levels of major histocompatibility complex (MHC) class I expression on their membrane, but not class II antigens. The enhancement of class I antigen synthesis occurs without a corresponding increase in synthesis of HBsAg by HBV genome positive PLC/PRF/5 and Hep3B cells. A 5 log dose of rIFN-gamma also did not trigger the integrated HBV genome into active replication as indicated by a lack of HBcAg and HBeAg synthesis. These results point to a possible role for the use of rIFN-gamma to enhance tumour cell recognition by the host immune system via the increased MHC class I expression.

Carcinoma, Hepatocellular↗