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Biomedical subjects

A M Chang

Publications and source records attributed to A M Chang.

At least 55 records · Page 3Linked to original sources
PubMed1999

Stress associated with tasks for family caregivers of patients with cancer in Hong Kong.

Family caregivers share the strain of cancer and are at risk of physical and psychological symptoms in relation to caregiver stress. This study investigated the relationships between perceived difficulty in managing caregiver tasks and the experience of stress symptoms among 26 family caregivers of terminally ill patients with cancer in Hong Kong. The findings revealed that more stress symptoms were experienced by caregivers who had reported increased difficulty in managing caregiver tasks (rs = 0.64; p < 0.001). Wilcoxon signed-ranks test indicated that psychological stress symptoms, rather than physical symptoms, overwhelmed most of the caregivers (z = -2.15; p < 0.05). There were significantly more negative responses to stress by caregivers who had a shorter duration of experience in providing care. In addition, caregivers who had less education were at higher risk of developing stress (p < 0.01). These findings indicate the need for the provision of support to facilitate the emotional and physical adaptation of caregivers at risk for health problems.

Adult↗
PubMed1999

Elevated mid-trimester maternal corticotrophin-releasing hormone levels in pregnancies that delivered before 34 weeks.

OBJECTIVE: To test whether maternal corticotrophin-releasing hormone levels are elevated in the mid- trimester for those women who subsequently had spontaneous preterm delivery and to assess the clinical utility of the measurement in the prediction of preterm delivery. DESIGN: A prospective observational study. SETTING: Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Hong Kong. POPULATION: 1047 low risk pregnant women recruited at 15-20 weeks of gestation. METHODS: Venous samples were assayed for levels of corticotrophin-releasing hormone. The investigators responsible for the laboratory assay were blinded to the obstetric outcome. MAIN OUTCOME MEASURES: Incidence of preterm, term and post-term pregnancies. RESULTS: Those who were delivered spontaneously at a preterm gestational age (before 34 weeks) had significantly higher corticotrophin-releasing hormone levels in the mid-trimester, compared with those who were delivered at term or post-term. There was a trend towards lower corticotrophin-releasing hormone levels with more advanced gestational age at delivery. When the measurement of corticotrophin- releasing hormone was used to predict delivery before 34 weeks, the best cut off was 1.9 MoM, which produced a sensitivity of 72.7% and specificity of 78.4%. This translated to a positive predictive value of 3.6%, negative predictive value of 99.6% and relative risk of 9.4 when the background prevalence of spontaneous preterm delivery before 34 weeks was 1.1%. The likelihood ratio was 3.4. CONCLUSIONS: Mid-trimester maternal corticotrophin-releasing hormone levels are elevated in pregnancies destined to deliver preterm before 34 weeks. When used alone in a low risk population, the measurement has a low predictive power for preterm delivery. However, the likelihood ratio of 3 4 implies that in high risk populations the test may be considerably more valuable.

Adult↗
PubMed1999

Clinical use of serum c-erbB-2 in patients with ovarian masses.

The c-erbB-2 (Her-2/neu) gene product has a large extracellular domain (ECD) and part of which could be identified in the serum. We measured the serum level of c-erbB-2 ECD in 93 patients, who presented with ovarian masses, with an enzyme immunoassay test and an elevated level was found in 5.5, 16.7 and 38% of patients with benign, borderline and malignant ovarian neoplasms, respectively. This serum marker may reflect the overexpression of c-erbB-2 gene in tumor tissues, which is associated with poor prognosis. However, measurement of c-erbB-2 ECD when used alone or in combination with CA 125 is not useful in differentiating benign from malignant ovarian tumors.

Adult↗
PubMed1999

Increased fetal DNA concentrations in the plasma of pregnant women carrying fetuses with trisomy 21.

BACKGROUND: The recent discovery of the presence of circulating cell-free fetal DNA in maternal plasma opens up new prenatal diagnostic applications and provides new avenues for clinical investigation. It is of research and potential diagnostic interest to determine whether fetal trisomy 21 may be associated with quantitative abnormalities of circulating fetal DNA in maternal plasma. METHODS: Maternal plasma samples were prospectively collected from two centers situated in Hong Kong and Boston. Samples collected from Boston consisted of 7 women carrying male trisomy 21 fetuses, 19 carrying euploid male fetuses, and 13 carrying female fetuses. Samples collected from Hong Kong consisted of 6 women carrying male trisomy 21 fetuses, 18 carrying euploid male fetuses, and 10 carrying female fetuses. Male fetal DNA in maternal plasma was measured using real-time quantitative Y-chromosomal PCR. RESULTS: For patients recruited from Boston, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 46.0 genome-equivalents/mL and 23.3 genome-equivalents/mL, respectively (P = 0.028). For patients recruited from Hong Kong, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 48.2 genome-equivalents/mL and 16.3 genome-equivalents/mL, respectively (P = 0.026). None of the samples from women carrying female fetuses had detectable Y-chromosomal signals. CONCLUSIONS: Abnormally high concentrations of circulating fetal DNA are found in a proportion of women carrying fetuses with trisomy 21. The robustness and reproducibility of real-time PCR analysis of maternal plasma makes it a valuable tool for cross-institutional collaboration involving centers located in different parts of the world.

Biomarkers↗
PubMed1998

Prospective randomized study of the effect of "add-back" hormone replacement on vascular function during treatment with gonadotropin-releasing hormone agonists.

BACKGROUND: Gonadotropin-releasing hormone agonists (GnRHas) are a group of drugs that with long-term use induce a pseudomenopausal state in which estrogen production is suppressed. They are commonly used in the treatment of sex steroid-dependent conditions. "Add-back" hormone replacement therapy is used to prevent menopause-like symptoms and bone loss during GnRHa treatment, but it is also recognized that hypoestrogenism adversely affects vascular function. The aim of this study was to examine the effect of GnRHa and add-back therapy on vascular reactivity. This model serves as a paradigm for the effect of hormone replacement therapy in postmenopausal women. METHODS AND RESULTS: Measurements of endothelium-dependent and endothelium-independent vascular reactivity were compared in 2 groups of women treated with a GnRHa for 6 months. One group received estrogen/progestogen add-back therapy during the second 3 months of GnRHa treatment. Vascular reactivity was examined by use of ultrasound measurements of changes in brachial artery diameter. Endothelium-dependent changes were assessed during reactive hyperemia, whereas endothelium-independent changes were measured after the administration of glyceryl trinitrate sublingual spray. Treatment with the GnRHa alone had an inhibitory effect on endothelium-dependent relaxation. However, endothelium-dependent relaxation significantly improved in the group receiving add-back therapy (14.6%) compared with the group treated with GnRHa alone (8.6%) (P<0.01). There were no significant endothelium-independent changes in either group. CONCLUSIONS: These results suggest that the administration of add-back therapy has a protective effect on vascular function in GnRHa-induced hypoestrogenism. As a model for the menopause, these results also suggest that the long-term administration of hormone replacement therapy would result in endothelium-dependent arterial relaxation, an observation previously attributed only to the acute administration of estrogen.

Adult↗
PubMed1998

Metabolic and inflammatory responses after laparoscopic and abdominal hysterectomy.

OBJECTIVE: Our purpose was to quantify and compare the metabolic and inflammatory changes after laparoscopic and abdominal hysterectomy. STUDY DESIGN: Forty-four patients with no major medical disease requiring abdominal hysterectomy for benign disorders were randomly assigned to have laparoscopic hysterectomy (n = 20) and abdominal hysterectomy (n = 24). Venous blood and 24-hour urine samples were collected the day before and for each of the first 3 postoperative days. RESULTS: No differences were present in demographic characteristics, operating time, and uterine weight between the two groups. No major complications were encountered. The laparoscopic hysterectomy group had a significantly lower postoperative morphine consumption (median 5.5 vs 14 mg, P < .05), lower febrile morbidity rate (15% vs 45.8%, P < .05), and shorter hospital stay (median 4 vs 6 days, P < .001) and demonstrated a less intense stress response in terms of serum interleukin-6 (median 50.6 vs 73.9 pg/mL x hour x 10, P = .01), C-reactive protein (median 28.1 vs 44.7 mg/L x hour x 10(2), P = .005), cortisol (median 23.4 vs 27.2 mg/mL x hour x 10(3), P = .04), white blood cell count (median 59.5 vs 69.8 10(9)/L x hour x 10, P = .009), 24-hour urinary excretion of cortisol (median 34.8 vs 44.2 nmol/L x hour x 10(3), P = .02), and norepinephrine (median 80.8 vs 132.4 nmol/L x hour x 10(2), P = .001). No significant difference was detected in plasma glucose (median 41.5 vs 45.6 mmol/L x hour x 10, P = 6) and 24-hour urinary excretion of epinephrine (median 32.2 vs 34.1 nmol/L x hour x 10(2), P = .3). CONCLUSION: Laparoscopic hysterectomy is associated with a lower morbidity and a less intense stress response than abdominal hysterectomy for benign diseases.

Abdomen↗
PubMed1998

Relationship between premenstrual tension syndrome and anxiety in Chinese adolescents.

This study examined the relationship between anxiety and premenstrual tension syndrome. One hundred and fifty-three schoolgirls completed Spielberger's Trait Anxiety Inventory and Abraham's Menstrual Symptom Questionnaire. The high level of trait anxiety found in this sample was related to an increase in premenstrual tension symptoms.

Adolescent↗
PubMed1998

Can health care assistants replace student nurses?

With the implementation of Project 2000 in the UK the traditional student nurse workforce has largely been replaced by health care assistants (HCAs). This study was carried out in Hong Kong at a time when university-based nurse education is gradually being introduced. Evaluation of a HCA pilot programme in an acute care hospital in Hong Kong provided the opportunity to examine the work of HCAs and hospital-based student nurses during the gradual introduction of university-based nurse education. The data used in this paper were drawn from a larger study evaluating the use of HCAs. The observational data collected at two phases after the introduction of HCAs were analysed using Kruskal-Wallis one way analysis of variance. No significant differences were found in the total amount of all types of activity performed by SNs and HCAs. However in the direct care type of work HCAs performed significantly more basic care and less technical activity than any level of student at phase 1 (P < 0.001) and phase 2 (P < 0.001). These differences in the work undertaken suggest that qualified staff do not perceive SNs and HCAs as equally unqualified. Thus the replacement of SNs with HCAs alone is likely to lead to a notable change in the role of qualified staff in terms of their direct and indirect care activities and in the amount of time spent delegating and supervising unqualified staff.

Health Care Reform↗
PubMed1998

Nursing activities following the introduction of health care assistants.

AIM: The purpose of this study was to determine changes in the work nature of nurses after the introduction of Health Care Assistants (HCAs). BACKGROUND: HCAs with a role similar to those adopted in the UK of assisting the nurse were piloted in a teaching hospital in Hong Kong. METHOD: A quasi-experimental design was used to compare the observed activities of HCAs and nurses in four wards of a teaching hospital, before and after the introduction of HCAs. As the amount of staff activity is influenced by the amount of work, patient dependency data were gained from record reviews and nurse interviews. FINDINGS: HCAs in orthopaedic and medical wards provided more basic care than those in surgical and gynaecological wards. Nurses in wards with HCAs performed significantly fewer activities than nurses in control wards. CONCLUSIONS: HCAs presence accounted for a reduction in both direct and indirect care provided by nurses. Overall, HCAs provided more basic than technical and indirect care.

Activities of Daily Living↗
PubMed1998

Quantitative analysis of fetal DNA in maternal plasma and serum: implications for noninvasive prenatal diagnosis.

We have developed a real-time quantitative PCR assay to measure the concentration of fetal DNA in maternal plasma and serum. Our results show that fetal DNA is present in high concentrations in maternal plasma, reaching a mean of 25.4 genome equivalents/ml (range 3.3-69. 4) in early pregnancy and 292.2 genome equivalents/ml (range 76. 9-769) in late pregnancy. These concentrations correspond to 3.4% (range 0.39%-11.9%) and 6.2% (range 2.33%-11.4%) of the total plasma DNA in early and late pregnancy, respectively. Sequential follow-up study of women who conceived by in vitro fertilization shows that fetal DNA can be detected in maternal serum as early as the 7th wk of gestation and that it then increases in concentration as pregnancy progresses. These data suggest that fetal DNA can be readily detected in maternal plasma and serum and may be a valuable source of material for noninvasive prenatal diagnosis.

DNA↗
PubMed1998

Spontaneous abortion: short-term complications following either conservative or surgical management.

Spontaneous abortion is a common gynaecological condition. It is a commonly held belief that medical morbidity associated with this condition is low and that routine treatment should be surgical evacuation of the uterus. This study was performed to study the short-term complications of spontaneous abortion and its management. Transvaginal sonography (TVS) was used to determine whether retained products of conception (POCs) were visible inside the uterus in women presenting with spontaneous abortion. If tissue was present, surgical evacuation of retained products of conception (ERPC) was performed. If the uterus was empty, the patients were managed expectantly. Four hundred and seventy women were treated with ERPC and 297 were managed expectantly. The complication rate was 3.0% in those managed expectantly compared with 5.8% for those treated by ERPC. Subjects with no POCs on TVS can therefore be managed expectantly without increasing the risk of morbidity associated with this condition.

Abortion, Incomplete↗
PubMed1998

Evaluation of the accuracy of transvaginal sonography for the assessment of retained products of conception after spontaneous abortion.

Transvaginal sonography (TVS) was used to assess uterine contents in 100 consecutive subjects presenting with a diagnosis of spontaneous abortion. TVS assessments were correlated with findings at subsequent evacuation of retained products of conception (ERPC). There was a strong correlation between the weight of the surgical specimen at ERPC with both the sagittal (r = 0.76; p < 0.05) and transverse (r = 0.73; p < 0.05) plane area measurements of the uterine cavity. Combining the 2 sonographic measurements increased the correlation to r = 0.81 (p < 0.05). Fifteen of 25 subjects who had been categorised to have an 'empty' uterus had less than 5 g of tissue removed and the other 10 subjects less than 10 g of tissue. In 20 of these 25 cases, the surgeon described the amount of curettings as 'small or non-significant'. TVS can accurately identify those women who do not have a significant amount of residual uterine tissue following spontaneous abortion.

Abortion, Incomplete↗
PubMed1998

MTAP gene deletion in endometrial cancer.

A gene (MTAP) that encodes the enzyme 5'-deoxy-5'-methylthioadenosine (MTA) phosphorylase has been identified on chromosome 9p21 and cloned. The substrate of this enzyme, MTA, inhibits aminopropyltransferases that synthesize polyamines from putrescine and decarboxylated S-adenosylmethionine. This enzyme normally cleaves MTA to adenine and 5'-methylthioribose-1-phosphate, which are recycled to adenine nucleotides and methionine, respectively. Cancers with deletions of the MTAP gene may be especially susceptible to chemotherapeutic regimes which interfere with purine or methionine utilization. The purpose of this study was to determine deletion of the MTAP gene in endometrial cancer using a polymerase chain reaction-based method. Therefore, 50 endometrial adenocarcinomas were studied. Partial or total deletions of the MTAP gene were detected in 7 (14%) of these cancers. There were no significant relationships between gene deletion and patient age, pathological grade or clinical stage (p > 0.05). The findings indicate that deletion of the MTAP gene does occur in a subgroup of endometrial cancer. The present work may be extended to the development of molecular diagnosis of MTAP gene deletion in other cancers and assist in selecting appropriate chemotherapy.

Adult↗
PubMed1998

State self-esteem following stroke.

BACKGROUND AND PURPOSE: Physical rehabilitation after stroke is often highlighted in the absence of consideration of psychosocial factors. This study sought to determine the relationship between state self-esteem and functional independence in patients recovering from stroke. METHODS: In a longitudinal study, data were collected from 152 stroke patients within 48 hours of admission to a rehabilitation hospital and at 2 weeks and 3 months after admission. The Modified Barthel Index was used to assess functional ability. Patients' current feelings of self-worth were assessed with use of the State Self-Esteem Scale. Additional variables included perceived social support, trait self-esteem, age, previous stroke, side of stroke, comorbidity, marital status, and gender. RESULTS: State self-esteem was significantly correlated to functional independence. The results of linear stepwise regression analysis indicated that functional ability and state self-esteem at 2 weeks, as well as the presence of heart disease, were significant predictors (55%) of functional ability at 3 months. For those with a functional ability score of >/=81 on admission to the rehabilitation unit, state self-esteem and functional ability at 2 weeks as well as previous stroke explained 53% of the variance in functional ability at 3 months. When functional ability was </=80, baseline and 2-week functional ability, state self-esteem at 2 weeks, and age predicted 53% of the variance in functional ability at 3 months. CONCLUSIONS: Functional ability at 2 weeks was a stronger predictor than baseline functional ability in this study. The level of state self-esteem was also a consistent factor in the prediction of functional outcome of patients after stroke.

Activities of Daily Living↗
PubMed1998

Site-selective differences in cytochrome P450 isoform activities. Comparison of expression in rat and rhesus monkey lung and induction in rats.

The distribution of pulmonary cytochrome P450 (P450 or CYP) isoforms has been investigated primarily in immunohistochemical studies, which are neither quantitative nor reflective of the functions of these enzymes. Studies of enzyme activities have been performed using whole-lung homogenates or isolated cells, but there is little information on the regioselective expression of P450 monooxygenases. The aims of this study were to compare the activities of P450 monooxygenases in different lung subcompartments in two commonly studied animal models, i.e. rats and monkeys, and to explore the possibility that inducing agents would result in activity up-regulation that is highly site-selective, using rats as a model. Microdissection techniques were used to separate the airways from blood vessels and lung parenchyma. In rats, CYP1A1 (ethoxyresorufin) and CYP2B (pentoxyresorufin) dealkylase activities were highest in the parenchyma, whereas CYP2E1 (p-nitrophenol) hydroxylase activity was highest in the airways. P450 reductase activities were similar in airways and parenchyma and were lower in trachea. In monkeys, no significant site-selective differences in CYP1A1 and CYP2B1 activities were found. In contrast, CYP2E1 activity was higher in the distal bronchioles and parenchyma than in the proximal airways. P450 reductase activities were similar in microsomes prepared from all subcompartments of monkey lung. Induction of rat CYP1A1 activity by beta-naphthoflavone (administered ip) was much greater in the airways and lung parenchyma ( approximately 30-fold) than in the liver ( approximately 10-fold) or trachea ( approximately 2.5-fold). Oral administration of phenobarbital or acetone increased CYP2B and CYP2E1 activities in rat liver but had no significant effect on P450 activities in subcompartments of rat lung. These findings support the conclusion that there are regiospecific and species-specific differences in the activities of P450 isoforms and that the inducibility of rat pulmonary P450s is dependent on the isoform and lung region.

Animals↗
PubMed1997

Frequent loss of heterozygosity of chromosome 3 short arm detected by PCR-based microsatellite polymorphisms in cervical squamous cell carcinoma.

Karyotypic studies have shown that genetic aberrations of the short arm of chromosome 3 (3p) may be involved in the pathogenesis of cervical carcinoma. In this study we analyzed nine polymorphic microsatellite repeats on 3p using a PCR-based assay for loss of heterozygosity (LOH) in 64 invasive squamous cell carcinomas of the cervix. These markers encompass chromosome region 3p13-25. LOH at one or more loci was detected in 46 (79%) out of the 58 informative cases. The incidence of LOH at locus D3S643 (3p13) was the highest among nine markers examined. The difference between the frequency of LOH at D3S643 in early stage (I-II) disease (43%) and those with advanced stage (stage III-IV) (79%) was statistically significant (P < 0.05). The results indicate that tumor suppressor gene(s) that play a role in cervical cancer may be located on the short arm of chromosome 3, likely near or at 3p13. The LOH at 3p13 appears to be a late event in tumor progression and may serve as an indicator for a less favorable clinical outcome.

Carcinoma, Squamous Cell↗
PubMed1997

Functional identification of the mouse circadian Clock gene by transgenic BAC rescue.

As a complementary approach to positional cloning, we used in vivo complementation with bacterial artificial chromosome (BAC) clones expressed in transgenic mice to identify the circadian Clock gene. A 140 kb BAC transgene completely rescued both the long period and the loss-of-rhythm phenotypes in Clock mutant mice. Analysis with overlapping BAC transgenes demonstrates that a large transcription unit spanning approximately 100,000 base pairs is the Clock gene and encodes a novel basic-helix-loop-helix-PAS domain protein. Overexpression of the Clock transgene can shorten period length beyond the wild-type range, which provides additional evidence that Clock is an integral component of the circadian pacemaking system. Taken together, these results provide a proof of principle that "cloning by rescue" is an efficient and definitive method in mice.

Animals↗