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Biomedical subjects

A M Chang

Publications and source records attributed to A M Chang.

At least 73 records · Page 4Linked to original sources
PubMed1997

p16INK4 and p15INK4B alterations in primary gynecologic malignancy.

Chromosome 9 abnormalities have been found in primary tumors and cell lines from human gynecologic malignancy. Alterations of p16INK4 and p15INK4B genes mapped on the band p21 of chromosome 9 have been detected in various human tumors, but the role of these genes as tumor suppressors in vivo appear to be dependent on tumor type. Polymerase chain reaction (PCR)-based analysis was performed to search for lesions of these genes in 202 primary gynecologic malignancies. Homozygous deletions of p16INK4 were detected in 7 of 128 (5%) cervical, 1 of 41 (2%) endometrial, 2 of 27 (7%) ovarian, and 3 of 6 (50%) vulvar carcinomas, while homozygous deletions of p15INK4B were detected in 19 of 128 (15%) cervical, 1 of 41 (2%) endometrial, 9 of 27 (33%) ovarian, and 3 of 6 (50%) vulvar carcinomas, respectively. No mutations were found in exon 2 of p16INK4 from 161 cases of gynecologic malignancy without deletion of p16INK4. All 3 cases of vulvar carcinoma showing homozygous deletions of p16INK4 and p15INK4B were at advanced clinical stage (stage III-IV), while all 7 cases of cervical carcinoma and 2 cases of ovarian carcinoma showing homozygous deletion of p16INK4 were at early stage (stage I-II). The results indicate that homozygous deletions of p16INK4 and/or p15INK4B genes may play a role in a subset of primary gynecologic malignancy.

Carrier Proteins↗
PubMed1997

The effect of different sampling intervals on the measurement of intrapartum fetal heart rate variability.

OBJECTIVE: To test the hypothesis that increasing the sampling interval affects the intrapartum fetal heart rate (FHR) variability measurement. METHODS: Fetal electrocardiograms were obtained from women in labor. Using the peak of the fetal R wave, the R-R interval and FHR were calculated on a beat-to-beat basis. Retrospectively, the original data were repartitioned using different intervals (2-900 seconds) to generate a window of measurement (epoch). The mean value for each epoch and the last FHR in that epoch (epochal value) were compared with published animal and human data. Errors were quantified by comparing the epochal and mean values for each epoch. Fetal heart rate variability between epochs and within each epoch was compared. RESULTS: Fetal heart rate and R-R interval were measured in 146 cases. The FHR had a normal distribution (mean 140.1 beats per minute, +/- standard deviation [SD] 15.6, skew -0.07), but its inverse, the R-R interval, was not normally distributed (mean 432 milliseconds, +/- SD 52.4, skew 1.78). Using a single value for an epoch duration of 2 seconds resulted in an error that was similar to the within-epoch variability (+/- SD of 2.2 beats per minute difference between mean and epochal value compared to +/- SD of 2 beats per minute within epoch) but which increased with epoch duration. CONCLUSION: An epoch duration of 2 seconds and a single sampled value within this period may be appropriate for measurement of both medium and long-term variability in any computerized intrapartum FHR interpretation system. Fetal heart rate (not R-R interval, because of its normal distribution) should be used to design such a computerized system.

Adult↗
PubMed1997

Antepartum and intrapartum prediction of cesarean need: risk scoring in singleton pregnancies.

OBJECTIVE: To demonstrate the use of generalized additive logistic regression in the development of a risk-scoring system to predict cesarean delivery. METHODS: Women who delivered in the Prince of Wales Hospital, Hong Kong, from 1994 to 1995 were the subjects of our study. Cases included were term singleton pregnancies with cephalic presentation, excluding those requiring cesarean delivery before labor. The cases were divided randomly into two sets. The prediction models were developed from set A and tested on set B, and vice versa. Maternal demographic and obstetric variables were used as potential predictors. Two models were formed, one before and one after the onset of labor. The generalized additive logistic regression was used to achieve optimal dichotomization of continuous measurements, and the predictive models were then developed. The validating results were pooled, represented, and compared as areas under receiver operating characteristic (ROC) curves. RESULTS: The first prediction model used maternal age, height, and weight at delivery as well as nulliparity, history of cesarean delivery, and the need for induction of labor. The second model had in addition the need for labor augmentation. The areas under the ROC curve for the models were 0.81 and 0.82, respectively, a statistically significant difference (z = 5.75, P < .001). CONCLUSION: The use of generalized additive logistic regression optimizes dichotomization of continuous measurements and facilitates the development of precise and reproducible prediction models. Generalized additive logistic regression appears to be a useful tool, and its use is commended.

Adult↗
PubMed1997

Evaluation of a health care assistant pilot programme.

Health Care Assistants (HCAs) were piloted in four wards of a large teaching hospital in Hong Kong. Evaluation of this pilot programme was based on patients' and nurses' satisfaction with HCAs, the HCAs' job satisfaction, and the retention rate of HCAs. Data were collected at 3 and 6-months following the introduction of HCAs to ascertain the level of satisfaction and the rate of HCA retention. Overall, the HCAs' work was seen as satisfactory and contributing to the work being carried out on each ward. Both nurses and patients were highly satisfied with HCA's, the mean total levels of satisfaction by nurses being 97 out of a possible range of 26-104 and for patients 53 out of a possible range of 14-56. While there was a high level of nurses' approval of introducing HCAs into the health care team there were significant differences (P < 0.05) with Nursing Officer, followed by Ward Managers being more in agreement than Registered Nurses. There were eight HCA activities seen by more than 70% of nurses to have been carried out frequently. The mean total job satisfaction of HCAs was 67 out of a possible 17-95. Although the 50% retention rate of HCAs was poor, there was overall satisfaction with the work of the HCAs.

Adolescent↗
PubMed1997

The mouse Clock mutation behaves as an antimorph and maps within the W19H deletion, distal of Kit.

Clock is a semidominant mutation identified from an N-ethyl-N-nitrosourea mutagenesis screen in mice. Mice carrying the Clock mutation exhibit abnormalities of circadian behavior, including lengthening of endogenous period and loss of rhythmicity. To identify the gene affected by this mutation, we have generated a high-resolution genetic map (> 1800 meioses) of the Clock locus. We report that Clock is 0.7 cM distal of Kit on mouse chromosome 5. Mapping shows that Clock lies within the W19H deletion. Complementation analysis of different Clock and W19H compound genotypes indicates that the Clock mutation behaves as an antimorph. This antimorphic behavior of Clock strongly argues that Clock defines a gene centrally involved in the mammalian circadian system.

Animals↗
PubMed1997

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line.

OBJECTIVE: To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour. DESIGN: Retrospective observational study. METHODS: Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor. The computerised algorithm for the baseline estimation was developed for intrapartum applications and is based on averaging modal fetal heart rate values. Evaluation was carried out on sixty cardiotocographic recordings by 12 experts and by the computer. These estimates were compared with those obtained from the computerised system using paired differences and intraclass correlation. RESULTS: The study showed that it is possible to produce a low frequency line from data obtained from intrapartum records. The system could not estimate the low frequency line in four records, whereas experts were also unable to estimate between one and seven tracings. The 95% CI for the paired differences between computer and experts was -12 to 15 bpm, whereas between the experts this was -10 to 10. With the exception of one expert, there was a high concordance between experts and between computer and experts (intraclass correlation > 0.9). CONCLUSIONS: The performance of this computerised algorithm cannot be distinguished from that of experienced clinicians. There were no significant differences between baseline values obtained by the computerised algorithm and those by the clinicians.

Algorithms↗
PubMed1997

C-myc mutation detected by polymerase chain reaction--heteroduplex in cervical cancer.

To evaluate both the incidence of c-myc gene mutation and the relationship of this finding to the clinico-pathologic characteristics of patients with cervical cancer, a polymerase chain reaction (PCR)-based heteroduplex gel electrophoresis method was used to screen DNA extracted from 102 cervical invasive carcinomas referred to the Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong. C-myc mutation was detected and then characterised by sequencing of PCR products in 4 cases (4%). The incidence of c-myc mutation in patients with advanced stage tumours (stage III-IV, 11% was statistically higher than in those with early stages (stage I-II, 1%, p = 0.05). There was also a significant difference in the incidence of c-myc mutation among the patients who had died of their disease (10%), were alive with evidence of disease (25%), and those without evidence of disease (0%, p = 0.0003). These findings indicate that the c-myc mutation is not common in cervical cancer, but where it exists, it may be associated with cancer progression and poorer outcome. Whether the c-myc mutation is an adjunct prognostic indicator in cervical cancer remains to be established in a larger study.

Base Sequence↗
PubMed1997

Lipid peroxidation in cord blood at birth: a marker of fetal hypoxia during labour.

OBJECTIVE: This prospective study examined purine metabolism in relation to free oxygen radical activity, as reflected by lipid peroxide levels in umbilical cord blood at birth. SETTING: Departments of Obstetrics and Gynaecology and of Chemical Pathology, the Chinese University of Hong Kong, Hong Kong, and Purine Research Laboratory, UMDS of Guy's and St. Thomas' Hospitals, London, UK. METHODS: Umbilical cord arterial and venous blood samples were collected from 132 singleton term deliveries for determination of hypoxanthine, xanthine, inosine, uric acid, organic hydroperoxides (OHP) and malondialdehyde. Oxygen saturation, PO2, pCO2, pH, and base excess (BE) were also measured. RESULTS: There was a significant correlation between umbilical arterial and venous levels of hypoxanthine, xanthine, inosine, uric acid and all acid-base parameters (p < 0.001). Significant arteriovenous differences were observed for all parameters with the exception of inosine, uric acid and OHP. Umbilical arterial xanthine and potassium correlated significantly with OHP, but hypoxanthine, inosine and uric acid did not. In 13 babies classified as severely asphyxiated at birth (umbilical arterial pH <7.15, BE <-8), xanthine and OHP levels were significantly elevated when compared with non-asphyxiated babies. No significant differences were observed for hypoxanthine, inosine or uric acid. CONCLUSION: The findings indicate that OHP, either in cord arterial or venous blood, is the best marker of free oxygen radical activity in the fetus, and that this correlates with other evidence of cellular hypoxia-reperfusion injury. We propose OHP is a better measure of perinatal outcome than either acid-base balance or hypoxanthine.

Adult↗
PubMed1997

Transvaginal sonographic assessment of cervical dynamics during the third trimester of normal pregnancy.

BACKGROUND: To obtain a normogram of measurements of the uterine cervix by transvaginal sonography during the third trimester of normal primiparous pregnancies and to relate these measurements to the events surrounding labor. METHODS: A prospective observational study, set in Guangzhou, Peoples Republic of China, was undertaken. Fifty-five normal nulliparous Chinese women with singleton pregnancies were studied from 30 weeks gestation until delivery. Serial transvaginal ultrasound examinations were performed at 30, 32, 34 and 36 weeks gestation and weekly thereafter. RESULTS: There was a significant correlation between gestational age and cervical length and width. Funnelling of the internal os was present in 25% of cases, and its earliest appearance was at 36 weeks. There was no consistent relationship between funnel length and width and gestational age. The duration of the first stage of labor was inversely correlated with the last ultrasound measurement of cervical length, but there was no relationship with either cervical width nor the presence of funnelling. The cervical changes in this population differed from those found in Caucasians. CONCLUSIONS: There is a direct relationship between both cervical width and length and gestational age and an inverse relationship with cervical length and the duration of labor. Funnelling of the internal os was not a predictor of the early onset of labor. The dimensions and features of the Asian cervix differ from those of the Europeans, and this should be considered when conducting further studies of a similar nature.

Cervix Uteri↗
PubMed1997

Laparoscopic management of adnexal mass during pregnancy.

BACKGROUND: To assess the use of laparoscopy in the management of persistent adnexal mass during the second trimester of pregnancy. SUBJECTS: Six consecutive pregnant women undergoing laparoscopic surgery for persistent adnexal masses in the second trimester. RESULTS: Laparoscopic removal of an adnexal mass was successfully performed in all patients. The median operating time was 37.5 minutes. There were no intra- and post-operative complications. Tocolytic therapy was not required and no patients developed uterine contractions. All patients delivered normal infants vaginally at term without complications. CONCLUSION: With attention to the surgical technique, laparoscopic removal of persistent adnexal mass during the second trimester of pregnancy is safe and carries the same benefits over laparotomy as in non-pregnant women.

Adult↗
PubMed1997

A medical approach to management of spontaneous abortion using misoprostol. Extending misoprostol treatment to a maximum of 48 hours can further improve evacuation of retained products of conception in spontaneous abortion.

BACKGROUND: To compare a 48 hour non surgical policy in the management of spontaneous abortion with a policy of routine, universal uterine curettage. METHODS: A prospective, observational study on 354 women admitted to hospital with spontaneous abortion. Of these, 225 who had retained products of conception were treated with misoprostol for up to 48 hours after 101 were excluded because they had an empty uterus on transvaginal scan (TVS) and another 28 women because they were unsuitable for conservative management. Follow-up was conducted over a 3 week period to assess morbidity. A reference group of 137 women, all of whom had an evacuation of retained products of conception (ERPC) as a routine after they had a TVS documenting retained products of conception (POCs), was used for comparison. RESULTS: Evacuation of the uterus occurred within 24 hours in 107 women and in 148 at 48 hours after misoprostol treatment was started. There were three uterine curettages up to 14 days after discharge from hospital for persistent bleeding and two cases of pelvic infection. An ectopic pregnancy was diagnosed at follow-up in one woman. In the reference group, there were nine women who had complications, four requiring another ERPC and five had infection, an overall complication rate of 6.6% in the reference group and 1.7% in the protocol treatment group. CONCLUSION: A 48 hour regimen using transvaginal ultrasound and misoprostol for the management of spontaneous abortion was successful in avoiding surgery in 249 out of a possible 354 (70.6%) women with spontaneous abortion, with a low rate of subsequent morbidity.

Abortifacient Agents, Nonsteroidal↗
PubMed1996

Coincidental renal cell and endometrial carcinoma: a case report.

A case of renal cell carcinoma and coexistent endometrial carcinoma is reported. The renal tumor in the lower pole of left kidney was detected by staging preoperative ultrasound scan and was confirmed to be a multilocular cystic renal cell carcinoma. There were two separate foci of moderately differentiated endometrial cancer in the endometrial cavity. Microscopic tumor deposits were also found in the left ovary and the right obturator pelvic lymph nodes. The multicentric involvement of endometrial cavity is uncommon and even rarer is the association with renal cell carcinoma. To the best of our knowledge, this is the first report of an association between renal cell carcinoma and endometrial cancer. This case demonstrates the importance of complete preoperative investigation before any definitive surgery for cancer. Without the abdominal ultrasound scanning, the asymptomatic renal cell carcinoma would probably have been undetected.

Adenocarcinoma↗
PubMed1996

A randomized, double-blind, placebo-controlled, crossover study on the effect of oral oestradiol on acute menopausal symptoms.

Acute menopausal symptoms occur less frequently in Asian than in Caucasian women. Oestrogen replacement therapy has been shown to be effective in controlling acute symptoms in Caucasians, but the effect of oestrogens is not well documented in Asian women. A randomized, double-blind, placebo-controlled, crossover study of the effect of oral oestradiol on the incidence of acute menopausal symptoms was conducted in 83 Hong Kong Chinese women who had experienced a surgical menopause. Although there was a significant increase in the oestradiol concentration with treatment compared with placebo (P < 0.001), there were no significant differences in the reporting of symptoms between the treatment and placebo groups. There is no obvious explanation for this apparent lack of effect of oestrogen on acute menopausal symptoms in Chinese women. Whilst it may be related to the generally low incidence of symptoms or to a higher dietary intake of phytoestrogens in Chinese women, further studies are necessary to explain these findings.

Administration, Oral↗
PubMed1996

Lipid peroxidation in cord blood at birth.

OBJECTIVE: The purpose of this study was to determine oxygen free radical activity in the neonate at birth and relate it to umbilical cord blood acid-base status. STUDY DESIGN: A series of 110 singleton deliveries had determination of two lipoperoxides in umbilical cord blood: malondialdehyde and organic hydroperoxide. Umbilical pH, PO2, PCO2, bicarbonate, and base excess were also measured. RESULTS: There was a significant association between lipoperoxides and cord blood pH and base excess. A significant difference existed in the levels of umbilical artery lipoperoxides between nonacidemic and acidemic fetus, as defined by an umbilical arterial pH < 7.20. CONCLUSION: There is a positive association between lipoperoxide production and acid-base balance at delivery.

Acid-Base Equilibrium↗
PubMed1996

HER-2/neu gene amplification in cervical cancer in Chinese women of Hong Kong and China.

OBJECTIVE: To determine the amplification of proto-oncogene HER-2/neu in invasive cervical cancer and its relationship with the stage of disease, grade of tumor and prognosis of patients. METHODS: In this retrospective study 70 women with invasive cervical squamous cell carcinoma were included. DNA was extracted from the paraffin-embedded tumor tissue. The amplification of HER-2/neu was studied using a differential polymerase reaction (PCR) technique. Assessment of significance was performed using Peason's Chi-square test and Fisher's exact test. RESULTS: Eleven of the 70 cases (16%) showed an amplification of HER-2/neu but there was no relation between amplification and tumor histologic grading (p = 0.408) or clinical staging (p = 0.180). Follow-up information in 67 patients was available. The incidence of amplification in the patients who were alive with disease was not statistically different from that in the patients who were alive with no evidence of disease (p = 0.315). The incidence of amplification in the patients who died of disease was higher than that in the patients who were still alive, but statistical significance did not reached (p = 0.062). CONCLUSION: The results suggest that HER-2/neu amplification does exist in a subgroup of invasive cervical cancer and may play a role in cervical carcinogenesis. The role as independent prognostic factor has to be evaluated by further prospective studies.

Base Sequence↗
PubMed1996

Fetal sex as a risk factor for fetal distress leading to abdominal delivery.

A retrospective analysis of perinatal information of 7,924 confinements in the calendar year of 1994 was performed to determine whether fetal sex was a significant risk factor for fetal distress in labour leading to abdominal delivery. The sex of the fetus (male) was a significant, independent, risk factor for Caesarean section (odds ratio = 1.26, 95% CI = 1.05 to 1.50). This increase was wholly attributable to the increased risk of having fetal distress in labour (odds ratio = 1.76, 95% CI = 1.32 to 2.34). Male fetuses are at higher risk of developing fetal distress during labour.

Cesarean Section↗