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Biomedical subjects

M S Rogers

Publications and source records attributed to M S Rogers.

At least 37 records · Page 2Linked to original sources
PubMed2001

Oxidative stress in the fetal lamb brain following intermittent umbilical cord occlusion: a path analysis.

OBJECTIVE: To evaluate the relative contribution of cord occlusion length intervals between occlusions and experimental duration on oxidative stress in the fetal lamb brain. DESIGN: Acute, partially exteriorised fetal lambs with intermittent total cord occlusion. SETTING: The Vivarium of Westmead Hospital, University of Sydney, Australia and The Chinese University of Hong Kong. MAIN OUTCOME MEASURES: Arterio-venous differences in the concentration of organic hydroperoxides, measured in paired samples of carotid arterial and jugular venous blood, as an index of oxidative stress in the brain. METHODS: Thirty-two fetal lambs were exposed to graded hypoxia, induced by intermittent total umbilical cord compression of 30 seconds, 60 seconds and 90 seconds duration, occurring every minute for a total of 27 occlusions over 81 minutes. Three sham experiments were also performed. In addition to organic hydroperoxides, carotid arterial blood samples were also assayed in 15 animals (two sham) for oxygen saturation, pH, hypoxanthine, xanthine and urate concentrations. A causal model for oxidative stress was defined: occlusions leading to hypoxia with a rise in hypoxanthine; reperfusion during intervals between occlusions leading to the accelerated production of xanthine and uric acid and the generation of oxygen free radicals, which in turn, are responsible for the rise in lipid peroxidation. Path analysis was performed to assess the strength of the relationships between these variables and the cord occlusion length, the interval between occlusions and the duration of the experiment. RESULTS: Sham experiments showed no change in organic hydroperoxide production. Following 30-second umbilical cord occlusions a sixfold drop in mean organic hydroperoxides was observed between carotid arterial and jugular venous levels. In contrast, following occlusions of 60 seconds duration (or longer) a median 20-fold increase in organic hydroperoxide production was observed. Path analysis revealed a strong indirect pathway from occlusion length --> hypoxanthine --> urate and weak positive pathways from oxygen saturation --> urate and from interval between occlusions --> urate. After accounting for these pathways reflecting oxidative stress, a strong direct path remained from time from first occlusion --> organic hydroperoxide production. CONCLUSIONS: Peroxidation of lipids in the brain occurs under conditions of severe hypoxia and reperfusion associated with intermittent umbilical cord occlusions of 60 seconds or longer. The path analysis supported the causal model as originally defined, with the exception that the indirect pathway via pH was found to be trivial.

Animals↗
PubMed2001

Reference intervals for thyroid hormones in pregnant Chinese women.

OBJECTIVE: To establish gestation-related reference intervals for thyroid hormones in a Chinese population. MATERIALS AND METHODS: A prospective study with 343 healthy pregnant women (5-41 weeks) and 63 non-pregnant controls. Thyroid stimulating hormone (TSH), free thyroxine (T4) and tri-iodothyronine (T3) (and human chorionic gonadotrophin) were measured by immunoassays. The median, 2.5th and 97.5th percentiles at 4-week intervals were calculated. Data were also analysed for significant trends using ANOVA. RESULTS: Free T3 decreased during pregnancy, whereas free T4 initially increased, peaking between 9-13 weeks and then decreased, the decline becoming significant by week 21. TSH mirrored changes in free T4. CONCLUSION: The gestation-related reference intervals for thyroid hormones should alleviate the misinterpretation of thyroid function in pregnancy.

Adult↗
PubMed2001

Are thyroid hormones or hCG responsible for hyperemesis gravidarum? A matched paired study in pregnant Chinese women.

OBJECTIVE: To determine the relative importance of thyroid hormones and human chorionic gonadotropin in the etiology of hyperemesis gravidarum. DESIGN: A prospective study comparing the hormonal status in women with hyperemesis gravidarum (5-18 weeks), with healthy pregnant controls, matched for gestational age. Sensitive thyroid stimulating hormone, free thyroxine, free triiodothyronine and total beta human chorionic gonadotropin were measured by immunoassays. The hormone results for hyperemesis gravidarum group (n=58) were compared with pregnant control women (n=58) using the Mann Whitney test. Stepwise logistic regression analysis was performed to determine which variables were significantly associated with hyperemesis gravidarum and to estimate the probability of each woman having hyperemesis gravidarum. The strength of the resulting association was tested by generating a receiver operating characteristic curve for predicting hyperemesis gravidarum using these probabilities. RESULTS: Maternal age and all hormones were significantly different between the hyperemetic and control groups. However, logistic regression analysis demonstrated that only maternal age, free thyroxine and thyroid stimulating hormone were significant independent variables. The area beneath the receiver operating characteristic curve for prediction of hyperemesis gravidarum was 0.84. CONCLUSION: Human chorionic gonadotropin is not independently involved in the etiology of hyperemesis gravidarum but may be indirectly involved by its ability to stimulate the thyroid. Differences in maternal age and thyroid function are highly discriminatory with regard to hyperemesis gravidarum.

Adult↗
PubMed2000

Complications of laparoscopic surgery for benign ovarian cysts.

STUDY OBJECTIVE: To assess complications of laparoscopic surgery in the management of ovarian cysts. DESIGN: Prospective observational study (Canadian Task Force classification II-2). SETTING: University-affiliated hospital. PATIENTS: Consecutive patients (513) undergoing laparoscopic surgery for ovarian cysts not suspected to be malignant. INTERVENTION: Laparoscopic surgery. MEASUREMENTS AND MAIN RESULTS: A total of 587 ovarian cysts were removed from 513 women. Conversion to laparotomy was necessary in five cases (<1%). Mean +/- SD cyst diameter was 5.5+/-2.9 cm, with endometriomas (44. 5%) and dermoids (24.3%) being the two most common pathologies; 6.6% were functional. Mean +/- SD operating time was 69+/-31 minutes, and hospital stay and postoperative convalescence was 2.6+/-1.5 and 14.3 +/-9.6 days, respectively. The overall complication rate was 13.3%. Major complications occurred in three patients (0.6%): one small bowel injury and two ureter injuries. Cannula site complications were five inferior epigastric vessel injuries and four incisional hernias at the 10-mm lateral port site. CONCLUSION: Laparoscopic ovarian surgery was associated with 13.3% complications, with 0.6% being major. Careful patient selection and proper surgical training are critical to ensure safe performance of laparoscopy.

Adult↗
PubMed2000

Color ultrasonography: a useful technique in the identification of nuchal cord during labor.

OBJECTIVE: To compare the accuracy of intrapartum ultrasound with and without color Doppler for identification of nuchal cord displacement during labor. METHODS: 180 normal pregnant women, admitted in labor, or for induction to labor, were examined independently by two researchers, using either conventional real-time gray-scale imaging or color Doppler imaging. A repeat examination was performed by the other researcher using the other ultrasound modality. Nuchal cord displacement was classified as either negative, definite or suspicious. Nuchal cord at birth was classified as either tight or loose. RESULTS: Sixty-two (34%) cases examined using the two ultrasound imaging modalities presented with nuchal cord at delivery. The sensitivity of color Doppler was 96.8%. The accuracy of color Doppler in detecting nuchal cord during labor was significantly better (P < 0.05) than gray-scale imaging alone. The results of a restricted sequential t-test analysis of 53 un-tied pairs showed an overall preference in favor of color Doppler assessment: statistical significance (P < 0.01) was reached after 41 un-tied pairs. CONCLUSIONS: The tight and loose nuchal cord could not be distinguished by ultrasound. Color Doppler imaging can provide useful additional information to gray-scale imaging in the detection of nuchal cord displacement during labor.

Female↗
PubMed2000

Effect of external cephalic version at term on fetal circulation.

OBJECTIVE: We sought to investigate the subclinical effect of external cephalic version on fetal circulation. STUDY DESIGN: A prospective observational study was conducted on 136 subjects who had external cephalic version at or beyond 36 weeks of gestation without clinical complication. Doppler ultrasonographic studies of the umbilical and middle cerebral circulations were performed before and after the external cephalic version. The following Doppler indexes were measured: (1) the pulsatility index of the umbilical artery, which represents disturbance of placental circulation, and (2) the pulsatility index of the fetal middle cerebral artery, which represents fetal response. The Wilcoxon signed rank test was used for all statistical analyses. RESULTS: There was no significant difference in pulsatility index of the umbilical artery before and after external cephalic version (P =.674). There was a statistically significant reduction in the pulsatility index of the middle cerebral artery after external cephalic version (P =.043), and this difference existed only among multiparous women (P =.029), among those in whom the external cephalic version was considered to be difficult (P =.038), and when the placenta was posteriorly located (P =.028). The reduction in pulsatility index was not related to whether the external cephalic version was successful. In all cases the Doppler indexes remained within the normal ranges, and there were no associated fetal complications. CONCLUSION: External cephalic version was not associated with any significant disturbance of placental resistance to blood flow. Conversely, external cephalic version was associated with a significant reduction in the pulsatility index of the middle cerebral circulation, especially among the multiparous women, after a difficult procedure or in those with a posterior placenta. This probably represents a normal fetal physiologic response to manipulation of the fetal head.

Bradycardia↗
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

Effect of labour and delivery on plasma hepatic enzymes in the newborn.

OBJECTIVE: To study the relationship between cord blood hepatic enzymes and obstetric and neonatal outcome in a Chinese population. MATERIALS AND METHODS: The study group consisted of 288 low-risk Chinese women with singleton term pregnancies. The following enzymes were assayed in cord blood: lactate dehydrogenase (LDH), glutamyl transferase (GGT), aspartate aminotransferase (AST) and alanine transferase (ALT). These were correlated to maternal and neonatal characteristics. RESULTS: A strong correlation was noted between cord blood AST and LDH (R = 0.582, p < 0.01), which was absent amongst those infants delivered by elective cesarean section. LDH, AST and ALT were negatively correlated with cord arterial pH and base excess (BE). GGT was inversely related only to gestational age (R = -0.18, p < 0.01). Both LDH and AST were weakly correlated with the duration of the first and second stages of labour. LDH was most closely linked to arterial pH, whereas AST was related to both arterial BE and duration of the second stage. CONCLUSIONS: The reference values are comparable to those published for Caucasian populations. There are moderate elevations in LDH and AST associated with the onset of labour and changes in acid-base status.

Acid-Base Equilibrium↗
PubMed2000

Determinants of umbilical cord arterial 8-iso-prostaglandin F2alpha concentrations.

OBJECTIVE: To determine the concentration of 8-isoPGF(2alpha) in cord blood as a measure of oxidative stress during labour, and to compare them with other established parameters of in vivo lipid peroxidation and with the acid-base status of the newborn. METHOD: Umbilical cord arterial and venous blood samples were collected from 81 singleton term deliveries for determination of 8-isoPGF(2alpha), malondialdehyde and organic hydroperoxides. In addition, metabolites derived from the oxidative metabolism of purines during hypoxia-reoxygenation and routine cord blood of oxygen saturation, pH, pO2, pCO2, HCO3 and base excess were measured. RESULTS: Arterial concentrations of 8-isoPGF(2alpha) were significantly higher in cases with fetal distress, tight nuchal cord (P < 0.001), the umbilical coiling index, and male sex (P < 0.05) (R2 = 0.48). No correlation was found with any parameter of acid-base status. In arterial and venous blood the concentrations of organic hydroperoxides and hypoxanthine significantly correlated with the fetal nuchal cord (P < 0.001) (R2 = 0.26 and 0.16, respectively). CONCLUSION: Our findings indicate that 8-isoPGF2(alpha) in cord arterial blood is a suitable parameter to quantify a possible oxidative stress in the fetus during labour. Measurements of the F2-isoprostane concentrations in cord blood at labour provide a clinically useful method to assess the perinatal outcome.

Acid-Base Imbalance↗
PubMed2000

Outcome of labour after successful external cephalic version at term complicated by isolated transient fetal bradycardia.

OBJECTIVES: To investigate factors associated with the occurrence of transient fetal bradycardia after external cephalic version, and labour outcome after isolated transient fetal bradycardia. DESIGN: Cohort study. SETTING: Teaching hospital with a policy of offering external cephalic version for breech presentation at or beyond 36 weeks of gestation. POPULATION: Four hundred and twenty-nine external cephalic versions performed over a 5-year period. METHODS: Between group differences were compared with the unpaired t test or the chi2 test. Logistic regression analysis was performed to exclude confounding effects. MAIN OUTCOME MEASURES: Incidence of caesarean section for fetal distress. RESULTS: Transient fetal bradycardia occurred in 8.4% of external cephalic versions, and was associated with a successful version (OR 16.45, P < 0.001), a difficult procedure (OR 3.70, P = 0.001), and nulliparity (OR 2.83, P = 0.007). The incidence of intrapartum caesarean section for fetal distress was 16.7% in pregnancies with transient fetal bradycardia, compared with 7.9% in those without (OR 2.34, 95% CI 0.81, 6.71). CONCLUSIONS: Transient fetal bradycardia after external cephalic version may be associated with a higher risk of intrapartum caesarean section for fetal distress.

Bradycardia↗
PubMed2000

A survey of pregnant women's attitude towards breech delivery and external cephalic version.

A structured interview survey was carried out in 150 women who came for their first antenatal visit in a university hospital in Hong Kong between June and July 1998. Their opinions and perceptions of fetal and maternal safeties on different modes of delivery for both cephalic and breech presentation, and external cephalic version (ECV) were surveyed. Their decisions on the management of term breech-presenting pregnancy were examined. Most women (92%) preferred vaginal delivery to Caesarean delivery (CS) in case of cephalic presentation, mainly because it was a natural way of parturition. They perceived that vaginal delivery was safer than CS for both mothers and babies, but the reverse was true for breech presentation. About 82% chose ECV as the first choice of managing breech presentation, mainly because a successful version allowed a natural way of delivery. Only 2% of women considered ECV ineffective, and 13.3% and 18.7% considered it not safe for mothers and fetuses respectively. Therefore, ECV should be an available option in all obstetric units. Adequate counselling and explanation would improve the acceptance of ECV.

Attitude to Health↗
PubMed2000

The 'right kind' of pain: talking about symptoms in outpatient oncology consultations.

Despite improvements in cancer management over the past 25 years, unrelieved symptoms continue to be reported. Little is known about how patients' problems and concerns are communicated to professionals during oncology treatment. This qualitative study investigates the process of communication between cancer patients and oncologists during consultations in outpatient clinics of a regional teaching hospital. Data were collected by nonparticipant observation and audiotaping consultations. Analyses were by qualitative content analysis and conversation analysis. An objectives, strategies and tactics model was applied to organize the findings. Seventy-four consultations between cancer patients and 15 doctors were observed and audiotaped. Pain talk is defined and identified as a substantial topic, occurring in 39 out of 74 consultations. Doctor-initiated questions are the predominant discourse feature and are prominent not only in initiating discussions but also in directing further talk (e.g. over three-quarters of doctor-initiated questions are in a closed form which focus narrowly on limited physical aspects of patients' pain). This limited information exchange is used alongside other communication tactics to identify the 'right kind' of pain that may benefit from cancer therapy and to truncate talk of problems perceived to be outside of this specialist remit. Although individualized, holistic care is the expressed philosophy of the clinic, our data show that doctors tightly control the agenda to focus narrowly on pain which was amenable to radiotherapy, chemotherapy, surgery or hormone manipulation. Inadequate exploration of patients' pain is likely to be detrimental to symptom control.

Adult↗
PubMed1999

Dichotomization of continuous measurements using generalized additive modelling--application in predicting intrapartum caesarean delivery.

In prediction model development, continuous variables are often dichotomized at empirically chosen thresholds to simplify calculations and facilitate decision making. However, these choices are often made in the absence of estimated covariate effects and may be inaccurate, thus weakening the models. To improve this approach, generalized additive modelling that allows non-parametric estimation of the true covariate effects is used for threshold selection. In this study, this approach is illustrated by development of prediction models for intrapartum Caesarean deliveries. The prediction performance of the models thus developed is significantly better than that developed using empirically chosen thresholds for dichotomization.

Adolescent↗
PubMed1999

Fetus papyraceous: an unusual cause of obstructed labour.

Fetus papyraceous is a relatively rare complication in twin pregnancy. The occurrence of fetus papyraceous is frequently associated with perinatal morbidity in the other twin, making antenatal diagnosis of this condition desirable. Ultrasound detection is not always possible due to anatomical position and technical difficulties. A case of fetus papyraceous, found during Caesarean section for obstructed labour is reported and the implications of antenatal detection are discussed.

Adult↗
PubMed1999

A comparison of three ultrasound estimates of intrapartum oligohydramnios for prediction of fetal hypoxia-reperfusion injury.

A prospective observational study assessed the predictive value of three techniques for amniotic fluid volume assessment on umbilical cord arterial lipid peroxide levels and acid-base balance. Women with singleton, term, cephalic presentation, and an initially normal fetal heart rate tracing were recruited. All pregnancies had the largest vertical pocket (LVP), two diameter pocket (2phi), and amniotic fluid index (AFI) assessments before and after amniotomy and cord arterial acid-base and lipid peroxide determinations at delivery. In 171 cases with confirmed cord arterial samples, malondialdehyde (MDA), organic hydroperoxide (OHP), pH and base excess (BE) were examined in relationship to intrapartum LVP, 2phi and AFI before and after amniotomy. Improvements in correlation between the estimates of amniotic fluid volume and outcome measures were observed 30 min after amniotomy, particularly with lipid peroxide measurements. Examination of scatter-plots using Lowess regression suggested that the correlation was only valid in cases of oligohydramnios but that the cutoff values recommended in the literature for defining oligohydramnios were not appropriate in our population sample. We suggest that oligohydramnios should be defined as an AFI < 8 cm or LVP < 4 cm. We concur with the recommendation of < 15 cm2 for the 2phi measurement.

Amniotic Fluid↗
PubMed1999

Loss of immunoreactivity for human calmodulin-like protein is an early event in breast cancer development.

Cell proliferation requires calmodulin, a protein that regulates calcium-dependent enzymes involved in signal transduction pathways in eukaryotic cells. Calmodulin-like protein (CLP) is found in certain epithelial cell types, including normal breast epithelium, and, although it closely resembles calmodulin in amino acid sequence, CLP interacts with different proteins than does calmodulin. The observation that CLP mRNA expression is dramatically reduced in transformed breast epithelial cells led to two hypotheses: (1) CLP helps to maintain the differentiated state in epithelial cells; and (2) downregulation of CLP accompanies malignant transformation of breast epithelial cells. The objective of this study was to determine if the expression of CLP in human breast cancer specimens is reduced in comparison to its expression in normal breast tissue. Eighty human breast cancer biopsy specimens were analyzed immunohistochemically for CLP expression by using a polyclonal rabbit antihuman CLP antibody. CLP expression was reduced in 79% to 88% of the invasive ductal carcinoma and lobular carcinoma specimens and in a similar fraction of the ductal carcinoma in-situ specimens, compared with normal breast specimens. None of the breast cancer specimens showed an increase in CLP expression. These findings support the hypotheses that CLP behaves as a functional tumor suppressor protein and is downregulated early in breast cancer progression.

Animals↗