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Biomedical subjects

E Wong

Publications and source records attributed to E Wong.

At least 91 records · Page 5Linked to original sources
PubMed2000

A transitional model of barrier methods compliance with unbalanced loss to follow-up.

Differential loss to follow-up can substantially influence the evaluation of treatment effects on a dichotomous outcome of interest in longitudinal trials. The use of transitional models incorporating loss to follow-up as an additional category of response and the nature of the correlated responses can provide a comprehensive view of a trial with unbalanced loss to follow-up. Under the Markov assumption, transitional models estimate the probability of changing from one outcome to another outcome between follow-up visits. Patterns of the response variable can be described by the estimated transition probabilities. The effects of intervention and covariates on the outcome of interest can also be estimated using a conditional likelihood function or a multinomial logit regression. Data from a randomized barrier method study designed to compare the proportion of participants using barrier methods consistently in two counselling groups are used to illustrate the proposed model.

Adolescent↗
PubMed2000

Lumbar spine imaging. Normal variants, imaging pitfalls, and artifacts.

Accurate recognition and reporting of spine abnormalities on MRI requires knowledge of normal anatomy and its variants. This article deals with common normal variants, points out pitfalls which may be sources of errors in interpretation and describes imaging artifacts which are essential to be recognized and not mistaken for true pathologies.

Artifacts↗
PubMed2000

Accuracy of clinical estimates of intraocular pressure in Chinese eyes.

PURPOSE: To investigate the validity of clinical estimates of intraocular pressure (IOP) in Chinese people. DESIGN: Prospective, cross-sectional, hospital-based in vivo study. PARTICIPANTS: Twenty-three ethnic Chinese adults (aged 35-82 years) undergoing routine phacoemulsification surgery were examined. TESTING: "True" IOP was measured with a solid-state hemodynamic monitor through a cannula in the anterior chamber. IOP was set successively to 10, 20, and 30 mmHg in each subject, using a reservoir of balanced salt solution. Intraocular pressure was simultaneously estimated by use of a hand-held applanation tonometer (Perkin's) and a Tono-Pen. The association between ocular biometric variables and measurement error was examined. MAIN OUTCOME MEASURES: The median of three readings at each IOP level was taken as the IOP estimate of each instrument. Measurement error was calculated as the mean difference (tonometer minus direct measurement). RESULTS: The error for the hand-held applanation tonometer was -1.6, -4.3 and -5.7 at 10, 20, and 30 mmHg, respectively. For the Tono-Pen the measurement error was +0.4, -2.0, and -4.1 at 10, 20, and 30 mmHg, respectively. We could identify no association between measurement error and corneal thickness or curvature, anterior chamber depth, or axial length. CONCLUSIONS: The applanation tonometer and Tono-Pen underestimate the true IOP in Chinese eyes. Error increases as true IOP increases. These tonometers do not give an accurate estimate of IOP in East Asians.

Adult↗
PubMed2000

General practitioner referral guidelines for dermatology: do they improve the quality of referrals?

Guidelines have proliferated in recent years in all areas of medicine, sometimes with little evaluation of their effect. Referral guidelines for dermatology were compiled by the dermatologist at the Royal Surrey County Hospital in consultation with local general practitioners. An audit was undertaken to assess how appropriate referrals were just before and after distribution of the guidelines and was repeated 2 years later to determine whether they had made any significant impact. The results revealed a 40% increase in the number of appropriate referrals immediately after introduction of the guidelines, but this was not sustained 2 years later. Five common conditions accounted for two-thirds of inappropriate referrals before and after the guidelines were sent. The need for continued general practitioner education in dermatology to reinforce referral guidelines is demonstrated.

Family Practice↗
PubMed2000

A pollen tube growth-promoting arabinogalactan protein from nicotiana alata is similar to the tobacco TTS protein.

Upon germination on the stigma, pollen tubes elongate in the stylar transmitting tract, aided by female factors, with speed and directionality not mimicked in in vitro pollen tube growth cultures. We have shown that a stylar transmitting tissue arabinogalactan protein (AGP) from Nicotiana tabacum (tobacco), TTS protein, stimulates pollen tube growth in vivo and in vitro and attracts pollen tubes grown in a semi-in vivo culture system. It has been reported that the self-incompatible Nicotiana alata produced a stylar glycoprotein, GaRSGP, which had a backbone polypeptide that shared 97% identity with those of TTS proteins but some of its properties were different from those described for TTS proteins. We report here the characterization of a family of stylar transmitting tissue glycoproteins from N. alata that is virtually identical to tobacco TTS proteins and which we refer to as NaTTS proteins. Like their tobacco counterparts, NaTTS proteins are recognized by the traditional AGP-diagnostic reagent beta-glucosyl Yariv reagent, and they are also recognized by JIM13, a monoclonal antibody against AGP. NaTTS proteins also stimulate pollen tube elongation in vitro and attract pollen tubes in a semi-in vivo pollen tube culture system. Biochemical and immunological characterization of NaTTS proteins revealed that they have extraordinary variability in the extent of sugar modifications of their polypeptide backbones. The extent of sugar modifications on NaTTS proteins significantly affects their biochemical properties, influences how they interact with the transmitting tissue extracellular matrix, and affects their solubility from this matrix. Our results suggest that the strategy used to purify GaRSGP only recovered a less glycosylated, more tightly extracellular matrix-bound sub-population of the entire spectrum of N. alata TTS proteins.

Electrophoresis, Gel, Two-Dimensional↗
PubMed2000

Factors predicting stroke disability at discharge: a study of 793 Chinese.

OBJECTIVE: To identify factors predicting stroke disability at discharge in a Chinese population. DESIGN: Retrospective analysis of data collected from stroke patients. SETTING: A 25-bed stroke rehabilitation unit in Hong Kong. PARTICIPANTS: A total of 793 Chinese patients with acute stroke consecutively admitted for inpatient rehabilitation. INTERVENTIONS: All patients received traditional rehabilitation therapies including physical, occupational, and speech therapies when appropriate. MAIN OUTCOME MEASURES: Disability was measured with the Barthel index (BI), and mild disability at discharge was defined as a BI score of > or =15. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed. RESULTS: Logistic regression analysis revealed that a BI score of > or = 15 points at admission strongly predicted that the patient's BI at discharge would be > or =15. For those whose BI score at admission was less than 15, these factors correlated negatively with a discharge BI of 15: BI at admission of <5 (OR .08, CI .04-.17); National Institutes of Health stroke scale at admission of >7 (OR .23, CI .12-.43); urinary incontinence at admission (OR .35, CI .21-.60); age > or =65 years (OR .44, CI .25-.77); and abbreviated mental test at admission of <7 (OR .56, CI .33-.94). CONCLUSIONS: For Chinese stroke patients, the disability at admission is the most important predictor for disability at discharge. Patients with very severe disability, severe neurologic impairment, urinary incontinence, old age, and impaired cognition at admission are less likely to recover to mild disability at discharge. Although hemorrhagic stroke is more common among Chinese populations, it is not an independent predictor for disability at discharge.

Aged↗
PubMed2000

Effect of remifentanil compared with fentanyl on intraocular pressure after succinylcholine and tracheal intubation.

Rapid sequence induction using succinylcholine is associated with an increase in intraocular pressure (IOP). This may lead to loss of ocular contents in open globe injuries. No method has previously been shown to prevent this increase in IOP. We investigated whether remifentanil, an ultra-short-acting opioid, could attenuate this increase in IOP during rapid sequence induction of anaesthesia. Forty-five patients were randomized blindly to receive remifentanil 1 microgram kg-1, fentanyl 2 micrograms kg-1 or placebo 1 min before thiopental, succinylcholine and tracheal intubation. IOP and haemodynamic variables were measured before, 1 min after the test solution, 30 s after thiopental, 30 s after succinylcholine, immediately after intubation and then every 3 min for 9 min. Remifentanil obtunded the increase in IOP after succinylcholine and intubation, so it could be suitable for use in open globe injuries.

Adult↗
PubMed2000

Hepatitis B prevalence in young women living in low-income areas: the population-based San Francisco Bay area's Young Women's Survey.

BACKGROUND: The risk of sexually transmitted hepatitis B virus infection is proportionally higher for young adults and women. Low socioeconomic groups have high rates of hepatitis B infection with no identified source of transmission. The prevalence and correlates of transmission of hepatitis B virus among young women of low socioeconomic status have not been well documented. GOAL: To determine the population-based prevalence and correlates of sexually acquired hepatitis B virus infection in young low-income women in the San Francisco Bay Area. STUDY DESIGN: A three-county, door-to-door serosurvey of hepatitis B virus core antibody among young women living in low-income areas was conducted from April 1996 to January 1998. Multivariate analysis of sexually acquired hepatitis B virus infection excluded participants of Asian or Pacific Islander ethnicity or with a history of intravenous drug use or transfusion. RESULTS: The prevalence of sexually acquired hepatitis B virus infection was 6.4% (95% CI, 4.7%-8.1%). Correlates of infection were black race (odds ratio, 3.9; 95% CI, 1.2-11.9 compared with white race) and herpes simplex virus type 2 infection (odds ratio, 2.0; 95% CI, 1.0-3.9). CONCLUSIONS: Young black women have a higher risk of sexually acquired hepatitis B virus infection. Herpes simplex virus type 2 infection may predispose to hepatitis B virus infection and/or be a marker for lifetime sexual risk behavior.

Adolescent↗
PubMed2000

Ectopic pregnancy--a diagnostic challenge in the emergency department.

The aim of this study was to elucidate the clinical presentation of ectopic pregnancy in the emergency department and highlight the atypical presentations and pitfalls in its diagnosis. This was a 4-year retrospective descriptive study carried out at a tertiary teaching hospital. Two hundred and seven cases of ectopic pregnancy treated in a tertiary teaching hospital were reviewed. Among the risk factors, 4.9% had a history of tubal ligation. Two patients developed ectopic pregnancy while breastfeeding. Of the patients, 43.7% did not have the triad symptoms of lower abdominal pain, vaginal bleeding and amenorrhoea. One patient presented with rectal bleeding while three patients presented with epigastric pain and central abdominal pain instead of lower abdominal pain. All who had tachycardia (10.4% of all cases) had ruptured ectopic pregnancy. Of the cases, 30% and 49% did not have abdominal pain and rebound tenderness respectively; 37.5% had negative cervical motion tenderness; 3.1% and 2.6% of cases had negative urine HCG and plasma beta HCG tests respectively. Ultrasound missed 1.6% of ectopic pregnancies. Missed pregnancy, normal ultrasound study and diagnosis of other gynaecological conditions were reasons for the delayed diagnosis of 5.8% of cases. There was one mortality. Any female in the reproductive age group with syncope, abdominal symptoms or any of the components of the classical triad must have ectopic pregnancy excluded. Patients with normal ultrasound studies should have their serum beta HCG levels and ultrasound scans repeated until the condition can be completely excluded. Transabdominal or transvaginal ultrasound studies done within the emergency department would enable earlier diagnosis and management.

Adolescent↗
PubMed2000

Leptin and metabolic hormones in infants of diabetic mothers.

AIMS: To investigate the effect of maternal diabetes on leptin in term newborns and to determine whether leptin correlates with insulin and its associated biochemical parameters in support of the hypothesis that a functional "adipoinsular axis" might exist at this stage of development. METHODS: A total of 116 term newborns were prospectively enrolled and categorised into three groups: 44 were infants of non-diabetic mothers (control group C); 41 were infants born to mothers with gestational diabetes on dietary treatment (group D); and 31 were infants born to mothers with gestational or pregestational diabetes on insulin treatment (group I). RESULTS: No significant difference in serum leptin was observed between the three groups; the results of the study population were therefore pooled and analysed. Serum leptin correlated significantly with serum insulin, insulin:glucose ratio, birth weight, body length, body mass index, placenta weight, and maternal HbA(1c). Female infants had significantly higher serum leptin than male infants. All parameters except placenta weight and body length remained significantly associated with serum leptin when multivariate stepwise regression analysis was applied. Subgroup analysis revealed a significant correlation between serum leptin and cortisol in group D. CONCLUSIONS: There was no significant difference in serum leptin between infants born to diabetic and non-diabetic mothers, though infants born to mothers requiring insulin treatment had the highest median serum leptin concentrations. The significant association between serum leptin and insulin or insulin:glucose ratio supports the hypothesis that a functional adipoinsular axis might exist in term newborns. Furthermore, the significant correlation between maternal HbA(1c) and circulating leptin of the studied infants suggests that the clinical control of maternal diabetes could affect the regulation of serum leptin in these infants.

Blood Glucose↗
PubMed2000

Leptin and metabolic hormones in preterm newborns.

AIM: To investigate the inter-relation between leptin and other metabolic hormones in preterm and term infants and to explore whether a functional "adipoinsular axis" might exist in preterm newborns. METHODS: A total of 140 preterm and term newborns were prospectively recruited and categorised according to gestation length. Blood samples were taken at 24 hours (day 1), and on day 4-5 of life. RESULTS: Serum leptin, cortisol, free thyroxine, and plasma ACTH on day 1 were significantly higher in term than in preterm infants. The relation between serum leptin and gestation followed a non-linear pattern; the slope of the curve began to increase steeply between 33 and 35 weeks gestation. Serum leptin on day 1 was significantly associated with serum insulin, insulin:glucose ratio, and plasma ACTH in infants less than 34 weeks gestation; serum leptin on day 1 and day 4-5 were significantly correlated with insulin:glucose ratio in infants 34 or more weeks gestation. Significant changes in the pattern of metabolic hormones were observed in the first week of life. Serum insulin and plasma glucose were significantly increased between day 1 and day 4-5; serum leptin was significantly decreased. CONCLUSIONS: The circulating leptin concentration increases markedly after 34 weeks gestation and bears a close temporal relation with the exponential accumulation of body fat mass during that period. The inter-relation between serum leptin and insulin or insulin:glucose ratio before and after 34 weeks gestation indicates that the "adipoinsular axis" is likely to be functional in early (<34 weeks gestation) intrauterine life. The rapid decline in the circulating concentrations of leptin after birth may be of physiological advantage to preterm and term newborns by limiting their body energy expenditure and conserving nutritional reverses for subsequent growth and development.

Adrenocorticotropic Hormone↗
PubMed2000

Keratinocyte growth factor-2 (FGF-10) promotes healing of experimental small intestinal ulceration in rats.

Keratinocyte growth factor-2 (KGF-2, repifermin) is a homolog of KGF-1 with epithelial mitogenic activities. We investigated the therapeutic role of KGF-2 in intestinal ulceration and its mechanisms of protection. KGF-2 (0.3-5 mg/kg) was administered before or after induction of small intestinal ulceration by indomethacin (Indo) in prevention and treatment protocols. In acute studies, KGF-2 was injected for up to 7 days before or daily for 5 days after Indo. In a 15-day chronic study, KGF-2 was injected intravenously daily beginning before or 7 days after Indo. Injury was evaluated by blinded macroscopic and microscopic inflammatory scores, epithelial BrdU staining, tissue IL-1beta, PGE(2), and hydroxyproline concentrations, and collagen type I RNA expression. In vitro effects of KGF-2 were evaluated by epithelial cellular proliferation, restitution of wounded monolayers, PGE(2) secretion, and expression of COX-2 and collagen mRNA. Intravenous KGF-2 significantly decreased acute intestinal injury by all parameters and significantly decreased chronic ulceration. Pretreatment, daily infusion, and delayed treatment were effective. KGF-2 promoted in vitro epithelial restitution with only modest effects on epithelial cell proliferation, stimulated COX-2 expression in cultured epithelial cells, and upregulated in vitro and in vivo PGE(2) production. KGF-2 did not affect in vivo fibrosis, although it induced collagen expression in cultured intestinal myofibroblasts. These results suggest that KGF-2 inhibits intestinal inflammation by stimulating epithelial restitution and protective PGs.

Acute Disease↗
PubMed2000

Do pain and disability differ in depressed cancer patients?

Seventy consecutively admitted Chinese patients with advanced cancer and pain (mean age 62 years) were evaluated with the Chinese version of the Hospital Anxiety and Depression Scale (HADS), and with the Geriatric Depression Scale (GDS) Short Form (for patients 65 years old or over) in a prospective study. The HADS and GDS had good concordance (kappa = 0.53). By these depression screening tests, the prevalence of probable depression was 41-49%, and the prevalence of definite depression (HADS > or = 11) was 29%. There was no difference in age, gender and educational level; no difference in nature and severity of pain; and no difference in the level of disability between depressed (using HADS > or = 11) and nondepressed patients with advanced cancer. The study suggests that depression does not correlate with the severity of pain in patients with advanced cancer. It also suggests that impaired activity of daily living (ADL) in these patients is not related to depression.

Activities of Daily Living↗
PubMed1999

Constitutive activation of stimulatory guanine nucleotide binding protein (G(S)alphaQL)-mediated signaling increases invasiveness and tumorigenicity of PC-3M prostate cancer cells.

An abnormal stimulation of cAMP signaling cascade has been implicated in various human carcinomas. Since the agents activating G(S)alpha-mediated signaling pathways have been shown to increase in vitro proliferation of prostate cancer cells, present studies examined the G(S)alpha-mediated signaling in tumorigenicity and invasiveness of PC-3M prostate cancer cells. PC-3M cells were stably transfected with plasmids containing either wild type (G(S)alpha-WT) or constitutively active (gsp mutant of G(S)alpha or G(S)alpha-QL) cDNAs. The stable transfectants were then tested for: (1) colony formation in soft agar; (2) cell migration and penetration of basement matrix in an in vitro invasion assay; and (3) the ability to form tumors and metastases in nude mice. PC-3M cells expressing G(S)alpha-QL protein displayed 15-fold increase in their ability to migrate and penetrate the basement membrane as compared to parental PC-3M cells or those expressing G(S)alpha-WT. G(S)alpha-QL transfectants also displayed a dramatically greater rate of growth in soft agar, and greater tumorigenicity and metastasis forming ability when orthotopically implanted in nude mice. All mice receiving PC-3M cells produced primary tumors within 5 weeks after implantation. However, the cells expressing G(S)alpha-QL displayed a significantly faster tumor growth as assessed by prostate weight (greater than 20-fold as compared to PC-3M cells), and produced metastases in kidneys, lymph nodes, blood vessels, bowel mesentery and intestine. Interestingly, expression of G(S)alpha-WT reduced the ability of PC-3M cells to form tumors in nude mice. These results suggest that persistent activation of G(S)alpha-mediated signaling cascade can dramatically accelerate tumorigenesis and metastasizing ability of prostate cancer cells.

Animals↗
PubMed1999

Mgm101p is a novel component of the mitochondrial nucleoid that binds DNA and is required for the repair of oxidatively damaged mitochondrial DNA.

Maintenance of mitochondrial DNA (mtDNA) during cell division is required for progeny to be respiratory competent. Maintenance involves the replication, repair, assembly, segregation, and partitioning of the mitochondrial nucleoid. MGM101 has been identified as a gene essential for mtDNA maintenance in S. cerevisiae, but its role is unknown. Using liquid chromatography coupled with tandem mass spectrometry, we identified Mgm101p as a component of highly enriched nucleoids, suggesting that it plays a nucleoid-specific role in maintenance. Subcellular fractionation, indirect immunofluorescence and GFP tagging show that Mgm101p is exclusively associated with the mitochondrial nucleoid structure in cells. Furthermore, DNA affinity chromatography of nucleoid extracts indicates that Mgm101p binds to DNA, suggesting that its nucleoid localization is in part due to this activity. Phenotypic analysis of cells containing a temperature sensitive mgm101 allele suggests that Mgm101p is not involved in mtDNA packaging, segregation, partitioning or required for ongoing mtDNA replication. We examined Mgm101p's role in mtDNA repair. As compared with wild-type cells, mgm101 cells were more sensitive to mtDNA damage induced by UV irradiation and were hypersensitive to mtDNA damage induced by gamma rays and H2O2 treatment. Thus, we propose that Mgm101p performs an essential function in the repair of oxidatively damaged mtDNA that is required for the maintenance of the mitochondrial genome.

Alleles↗