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Biomedical subjects

W H Tam

Publications and source records attributed to W H Tam.

At least 19 recordsLinked to original sources
PubMed2006

Oxidative stress in midpregnancy as a predictor of gestational hypertension and pre-eclampsia.

OBJECTIVES: To explore the relationship between the levels of maternal oxidative stress and glycaemia during pregnancy and to compare the predictive values of 8-epimer of prostaglandin F(2alpha) (8-isoPGF(2alpha)) and mean arterial pressure (MAP) in midpregnancy for the development of hypertensive complications in later pregnancy. DESIGN: Prospective observational study as an ancillary study to the Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) study. SETTING: Obstetric clinics and wards of a university teaching hospital in Hong Kong. POPULATION: Selected women with singleton pregnancies attending the antenatal clinic. METHODS: Pregnant women who met HAPO inclusion criteria were recruited for the study. Glucose tolerance was assessed by a 75-g 2-hour oral glucose tolerance test (OGTT) at 24-32 weeks of gestation. Fasting plasma samples for 8-isoPGF(2alpha) estimation and urine samples for 8-isoPGF(2alpha) and 2,3-dinor 8-isoPGF(2alpha) assays were collected and blood pressures measured during the OGTT visit. Random plasma and urine samples were also obtained at 34-37 weeks. Glucose results were unblinded to the attending obstetrician if limits preset under the HAPO protocol were met. MAIN OUTCOME MEASURES: Maternal plasma 8-isoPGF(2alpha) and urinary 8-isoPGF(2alpha) and 2,3-dinor 8-isoPGF(2alpha) both at the time of OGTT (24-32 weeks) and at 34-37 weeks of gestation. Incidence of pre-eclampsia and gestational hypertension. RESULTS: Of the 408 women who attended for OGTT at 24-32 weeks, two met the glucose criteria for unblinding and 25 had missing 8-isoPGF(2alpha) values and thus were excluded from analysis. Of the 381 women, 338 (88.7%) attended for random plasma samples at 34-37 weeks. Significant correlations were observed between maternal fasting plasma isoprostane and both fasting (r= 0.20; P < 0.001) and 2-hour (r= 0.39; P < 0.001) plasma glucose levels at the time of OGTT. Gestational hypertension/pre-eclampsia occurred in 17 (4.2%) women, and at the time of OGTT, they had significantly higher fasting plasma 8-isoPGF(2alpha) (P < 0.001), urine 8-isoPGF(2alpha) (P < 0.005) and urine 2,3-dinor 8-isoPGF(2alpha) to creatinine ratios (P < 0.001), as well as higher MAP (P < 0.001) than women who remained normotensive. At 34-37 weeks, only random plasma 8-isoPGF(2alpha) was significantly higher (P < 0.001) among the women with gestational hypertension/pre-eclampsia. CONCLUSIONS: Plasma markers of oxidative stress were positively correlated with plasma glucose at the time of OGTT (24-32 weeks). Women who subsequently developed gestational hypertension/pre-eclampsia had significantly higher plasma and urine markers of oxidative stress at the time of OGTT but only higher plasma markers at 34-37 weeks. Plasma 8-isoPGF(2alpha) appears to be a very good predictor of subsequent gestational hypertension/pre-eclampsia when measured at the time of OGTT, but its ability to discriminate deteriorates as pregnancy advances.

Adult↗
PubMed2003

Sociodemographic and atopic factors affecting breastfeeding intention in Chinese mothers.

OBJECTIVE: The factors accounting for the low 'ever breastfeeding' rate in Hong Kong remain unclear. The objective of this survey was to study the intention and planned duration of breastfeeding in Chinese women in Hong Kong, and to investigate the sociodemographic and atopic factors affecting the intention to breastfeed. METHODS: All Chinese mothers who were Hong Kong residents and who delivered their babies in a University teaching hospital were given a self administered and anonymous Chinese questionnaire within 1 day postpartum. The questionnaire included items on sociodemographic data, the presence of allergic diseases in the families, and the intention and planned duration of breastfeeding for their newborn babies. RESULTS: A total of 1374 eligible questionnaires were collected. About one-third of mothers were born outside Hong Kong and the majority (78%) of them were aged between 25 and 40 years. Logistic regression revealed that only socioeconomic factors, namely older maternal age (odds ratio (OR) 2.10, 95% confidence interval (CI) 1.14-3.89), parity (OR 3.08, 95% CI 1.02-9.27) and higher educational background (OR 2.87, 95% CI 1.92-4.27), significantly affected the intention to breastfeed. In addition, mothers born outside Hong Kong and those with first babies, had a longer intended duration of breastfeeding (P-values < 0.001 and 0.033, respectively). A family history of atopic disorders in parents or siblings did not influence the breastfeeding intention of these Chinese mothers. CONCLUSION: Several sociodemographic factors, rather than a history of atopic disorders, of Chinese mothers in Hong Kong affected their intention to breastfeed and the planned duration of breastfeeding.

Adult↗
PubMed2002

A randomised controlled trial of intramuscular syntometrine and intravenous oxytocin in the management of the third stage of labour.

OBJECTIVE: To compare the efficacy and safety of intravenous oxytocin with intramuscular syntometrine in the management of the third stage of labour. DESIGN: A prospective randomised trial. SETTING: A university teaching hospital. METHODS: A total of 991 women having a singleton pregnancy and vaginal delivery were randomised by a computer-generated number to receive either 1 ml syntometrine intramuscularly or 10 units of intravenous Syntocinon after delivery of the anterior shoulder of the fetus. MAIN OUTCOME MEASURES: Blood loss during delivery, rate of postpartum haemorrhage, need for repeated oxytocics, haemoglobin level before and 24 hours after delivery, duration of third stage, need for manual removal of placenta and sides effects including hypertension, nausea, vomiting, headache and chest pain. RESULTS: The use of intravenous oxytocin was associated with a reduction in postpartum blood loss (P < 0.001) but there was no difference in the risk of postpartum haemorrhage in the need for repeated oxytocic injections and the drop in peripartum haemoglobin level between the two groups. There was also no difference in the risk of prolonged third stage, or in the need for manual removal of placenta. The use of syntometrine was associated with a higher risk of hypertension (RR 2.39, 95% CI 1.00-5.70). Other side effects were mild in nature with no differences between the two groups. CONCLUSIONS: There are no important clinical differences in the effectiveness of intramuscular syntometrine and intravenous oxytocin for the prevention of postpartum blood loss. Intravenous oxytocin is less likely to cause hypertension.

Adult↗
PubMed2001

High carriage rate of TT virus in the cervices of pregnant women.

Prevalence studies of the recently identified TT virus (TTV) have suggested that parenteral transmission is a common route of infection, but other routes also appear likely. In this study, a high rate of cervical carriage (66%) of TTV DNA was found by polymerase chain reaction, which suggests that perinatal and sexual transmission is possible.

Adolescent↗
PubMed2001

Venous thromboembolism in pregnant Chinese women.

OBJECTIVE: To evaluate the incidence, disease pattern, and risk factors for thromboembolism in pregnant Chinese women. METHODS: We conducted a study from January 1998 to December 2000. Women with thromboembolic diseases were identified and their case records retrieved and reviewed. Demographic characteristics were compared between women with and without thromboembolism. RESULTS: Thirty-two women were diagnosed as having thromboembolic disease during the study period. The total number of deliveries over the study period was 16,993, giving an incidence of 1.88 per 1000 deliveries. There were two cases of pulmonary embolism and one resulted in a maternal death. The others had deep vein thrombosis of which over 80% were limited to calf veins only. The ultrasound examinations requested for suspected deep venous thrombosis before and after the event of maternal death were 1.62 and 10.7 per 1000 deliveries (P <.001); and the corresponding cases of deep venous thrombosis diagnosed were 0.29 and 2.94 per 1000 deliveries, respectively (P <.001). The majority (75%) of cases were diagnosed in the postpartum period, mainly after cesarean delivery. Women with venous thromboembolism were older, had higher body mass index, and a higher incidence of preeclampsia. CONCLUSION: Thromboembolic disease is not uncommon among pregnant Chinese women. The incidence was similar to that of the white population, although the sites of vascular occlusion were different. The long-standing belief that thromboembolism is rare among Chinese is at least partly because of underdiagnosis.

Asian People↗
PubMed2001

Ovarian stanniocalcin in trout is differentially glycosylated and preferentially expressed in early stage oocytes.

The stanniocalcin (STC) gene was recently found to be widely expressed in fish. In this study, we have characterized ovarian STC in the rainbow trout (Oncorhynchus mykiss) and cloned the ovarian cDNA. The STC gene expression was highest in early stage oocytes and diminished progressively as oocytes developed. At the cellular level, ovarian STC gene expression was most abundant in the ooplasm of early stage oocytes, but it was also weakly evident in the theca layer, interstitial cells, and vitellogenic oocytes. The STC protein was distributed in a pattern similar to that of gene expression but was also apparent in glycoprotein vesicles, nuclei, multivesicular bodies, and follicles undergoing atresia. Cloned cDNAs obtained from the corpuscles of Stannius (CS) and ovarian transcripts were nearly identical. However, Western blotting of the partially purified proteins revealed that ovarian STC was larger than CS STC. Further analysis revealed that ovarian STC had a much larger N-linked carbohydrate moiety (approximately 12 kDa) compared to CS STC (approximately 7 kDa), indicating that the two hormones were differentially posttranslationally modified. To our knowledge, this is the first characterization of STC gene expression, cDNA, and protein distribution in the piscine ovary and the first evidence for any difference between alternative sources of the hormone in any species.

Amino Acid Sequence↗
PubMed2001

The predictive value of serum 1,5-anhydro-D-glucitol in pregnancies at increased risk of gestational diabetes mellitus and gestational impaired glucose tolerance.

The objective of the study was to determine the efficacy of 1,5-anhydro-D-glucitol (1,5 AG) for the prediction of gestational diabetes and gestational impaired glucose tolerance (GIGT). One hundred and eighty-five pregnant women with epidemiological risk factors of gestational diabetes or GIGT underwent 75 g oral glucose tolerance test and plasma 1,5 AG assay at 26 to 28 weeks of gestation. There was no significant difference in plasma 1,5 AG either before or after an oral glucose load. The area under the receiver operator characteristic curve for 1,5 AG was only 0.485 which implies that 1,5 AG is a poor predictor of GIGT or gestational diabetes.

Adolescent↗
PubMed2001

Risk and prediction of preterm delivery in pregnancies complicated by antepartum hemorrhage of unknown origin before 34 weeks.

OBJECTIVE: To assess the timing and risk factors of preterm delivery in pregnancies complicated by antepartum hemorrhage of unknown origin (APHUO) before 34 weeks of gestation, and to formulate a clinical management protocol. METHODS: A retrospective study involving singleton pregnancies with APHUO occurring before the 34th week of gestation was performed over a 4-year period at a university teaching hospital. RESULTS: Seventy-five cases were identified. Fifty-nine (78.7%) did not have any associated uterine contractions, 74.7 and 90.7% of the cases were classified as having mild bleeding according to history and physical examination, respectively. The number of cases delivering before 37 weeks of gestation and before 34 weeks were 28 (37.3%) and 22 (29.3%), respectively. Eighteen cases (24%) delivered within the first week of APHUO, and 4 (5.3%) within the first day. The number of cases delivering within the first week was significantly higher when there were uterine contractions (62.5 vs. 13.6%, p < 0.001). The severity of bleeding was not shown to be related to the time of delivery. CONCLUSION: APHUO that occurs before 34 weeks is associated with a high risk of preterm delivery before 34 weeks (29.3%). The chance of delivery within the first week is 62.5% when there are coexisting uterine contractions. Even if contractions are absent, the risk is still high (13.6%) and persists beyond the first week. We suggest that this group of patients should be managed with a course of steroid injection and hospitalization for 4 days.

Female↗
PubMed2000

The incidence of pregnancy-induced hypertension among patients with carbohydrate intolerance.

OBJECTIVE: To determine the association between pregnancy-induced hypertension (PIH) and carbohydrate intolerance in pregnancy. METHODS: Data on singleton pregnancies were retrieved from the obstetric database of University Hospital, Kuala Lumpur. Gestational impaired glucose tolerance (GIGT) and gestational diabetes mellitus (GDM) were defined according to the World Health Organization criteria. Established diabetes mellitus (EDM) was defined as diabetes mellitus diagnosed prior to pregnancy. PIH was diagnosed according to the criteria of the International Society for the Study of Hypertension in Pregnancy. Maternal characteristics were compared between groups using analysis of variance (ANOVA) and incidence counts using the chi-squared test. Logistic regression analysis using the presence of PIH as the response variable was used to study the association among GDM, GIGT, EDM, and PIH, controlling for maternal factors. MAIN OUTCOME MEASURES: To determine the incidence of PIH among patients with glucose intolerance and the independent risk factors for the development of PIH. RESULTS: There were 24,290 singleton pregnancies retrieved from the database. Both the prevalence of carbohydrate intolerance and the incidence of PIH differed among the three principal ethnic groups (p < 0.0001). There was a significant association between PIH and both a higher maternal age (OR = 1.04, p < 0.0001) and a higher maternal body mass index (BMI) at delivery (OR = 1.14 per unit increment, p < 0.0001). After adjusting for maternal age, BMI, parity, and ethnic origin, using logistic regression, there was a significant residual risk of PIH among individuals with GIGT, GDM, or EDM. CONCLUSIONS: Patients with carbohydrate intolerance of varying severity are at increased risk of developing PIH. Our findings lend credence to the theory that carbohydrate intolerance and PIH share a common etiology.

Comorbidity↗
PubMed2000

A randomised double-blind placebo-controlled trial of transcervical intrauterine local anaesthesia in outpatient hysteroscopy.

OBJECTIVE: To assess whether transcervical intrauterine instillation of local anaesthetic agent reduces pain during diagnostic outpatient hysteroscopy and endometrial biopsy. DESIGN: Prospective, randomised, double blind, placebo-controlled trial. SETTING: Outpatient hysteroscopy clinic in a university teaching hospital. POPULATION: Ninety women undergoing outpatient diagnostic hysteroscopy with or without endometrial biopsy. METHODS: Transcervical intrauterine instillation of 5 mL of 2% lignocaine into the uterine cavity before performing the procedure. MAIN OUTCOME MEASURES: Evaluation of pain at different stages of the procedure using a visual analogue scale and changes in blood pressure and heart rate. RESULTS: The use of local anaesthetic did not alleviate pain experienced during hysteroscopy and endometrial biopsy. It did not prevent the occurrence of vaso-vagal reactions; however the incidence of these was low. CONCLUSIONS: Transcervical instillation of local anaesthesia neither reduced pain nor prevented vaso-vagal reaction during hysteroscopy and endometrial biopsy.

Administration, Topical↗
PubMed1999

Paracervical anaesthesia in outpatient hysteroscopy: a randomised double-blind placebo-controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of paracervical anaesthesia in reducing pain during outpatient hysteroscopy and endometrial biopsy. DESIGN: Prospective, randomised, placebo-controlled, double-blind study. POPULATION: One hundred women undergoing outpatient hysteroscopy and endometrial biopsy for abnormal uterine bleeding. INTERVENTIONS: Paracervical block using 10 mL of either 2% lignocaine or normal saline before the procedure. MAIN OUTCOME MEASURES: Evaluation of pain at different stages of hysteroscopy using a visual analogue scale together with blood pressure and heart rate monitoring. RESULTS: Compared with placebo, paracervical anaesthesia significantly reduced the pain only at the time of insertion of the hysteroscope, but not at the subsequent stages of the procedure. However, paracervical injection of lignocaine resulted in a higher incidence of bradycardia and hypotension. CONCLUSIONS: Paracervical anaesthesia not only fails to reduce pain during outpatient hysteroscopy and endometrial biopsy, but also carries a risk of inducing bradycardia and hypotension, which is probably a result of inadvertent intravascular injection.

Adult↗