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Biomedical subjects

S McDonald

Publications and source records attributed to S McDonald.

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

Prophylactic use of oxytocin in the third stage of labour.

BACKGROUND: Many maternal deaths across the world result from complications of the third stage of labour (when the placenta is delivered). OBJECTIVES: To examine the effect of oxytocin given prophylactically in the third stage of labour on maternal and neonatal outcomes. SEARCH STRATEGY: Relevant trials were identified in the Cochrane Collaboration Controlled Trials Register and the Pregnancy and Childbirth Review Group's Specialised Register of Controlled Trials. Date of last search: May 2001. SELECTION CRITERIA: All acceptably randomised or quasi-randomised controlled trials including pregnant women anticipating a vaginal delivery where oxytocin was given prophylactically for the third stage of labour. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed studies for relevance and methodological quality, and extracted data. Analysis was by intention to treat. Subgroup analyses were based on extent of selection bias, oxytocin in the context of active or expectant management of the third stage, and timing of administration. Results are presented as relative risks, and weighted mean difference, both with 95% confidence intervals using a fixed effects model. MAIN RESULTS: In seven trials involving over 3000 women in hospital and/or developed country settings, prophylactic oxytocin showed benefits (reduced blood loss (relative risk (RR) for blood loss > 500 ml 0.50; 95% confidence interval (CI) 0.43, 0.59) and need for therapeutic oxytocics (RR 0.50; 95% CI 0.39, 0.64).) compared to no uterotonics, although there was a non-significant trend towards more manual removal of the placenta (RR 1.17; 95% CI 0.79, 1.73) which was most marked in the expectant management subgroup, and blood transfusions (RR 1.30; 95% CI 0.50, 3.39) in the trials with more manual removals of the placenta). In six trials involving over 2800 women, there was little evidence of differential effects for oxytocin versus ergot alkaloids, except ergot alkaloids are associated with more manual removals of the placenta (RR 0.57; 95% CI 0.41, 0.79), and with the suggestion of more raised blood pressure (RR 0.53; 95% CI 0.19, 1.58) than with oxytocin. In five trials involving over 2800 women, there was little evidence of a synergistic effects of adding oxytocin to ergometrine versus ergometrine alone. For all other outcomes in the comparisons either there are no data or the number of adverse events is very small, and so definite conclusions cannot be drawn. REVIEWER'S CONCLUSIONS: There are strong suggestions of benefit for oxytocin in terms of postpartum haemorrhage, and the need for therapeutic oxytocics, but without sufficient information about other outcomes and side-effects it is difficult to be confident about the trade-offs for these benefits, especially if the risk of manual removal of the placenta may be increased. There seems little evidence in favour of ergot alkaloids alone compared to either oxytocin alone, or to Syntometrine, but the data are sparse. More trials are needed in domiciliary deliveries in developing countries, which shoulder most of the burden of third stage complications.

Ergot Alkaloids↗
PubMed2001

Why barium enemas fail to identify colorectal cancers.

BACKGROUND: The aim of the present study was to determine the cause and clinicopathological factors associated with the failure of barium enemas to detect colorectal cancers. METHODS: A histopathological database was used to identify all patients with a diagnosis of colorectal cancer between 1991 and 1995. These records were matched with the records from patients who underwent barium enema examinations between 1990 and 1995. Those patients who had a colorectal cancer histologically diagnosed within 24 months of a barium enema in which no carcinoma was seen, were identified. Where possible the radiology was reviewed. Failure to identify a carcinoma was then attributed to either simple failure, technical, interpretive or perceptive difficulties. RESULTS: There were 967 patients with colorectal cancers treated in Christchurch Hospital during the study period 1991-1995. Matching of these patient details with all barium enema records revealed 313 patients who had barium enemas and histologically proven colorectal cancer. There were 21 (6.7%) patients in whom a carcinoma was missed. Of these, 18 had a barium enema within 8 months of surgery, and three were performed outside this timespan (15, 18 and 28 months, respectively). On review, 11 carcinomas could not be identified (nine due to technical error: poor coating (n = 1), overlapping loops (n = 3), single-contrast enema (n = 4), faecal residue (n = 1)); and seven could be seen on review of the films (two interpretation errors, one technical and perceptive error, and four perceptive errors). In three cases films could not be found for review. In 16 of the 21 missed lesions the patient had a double-contrast barium enema (DCBE) while five patients had single-contrast barium enema (SCBE). The site and stage of missed tumours is presented. CONCLUSIONS: The most common reason for missed tumours was technical. The percentage of missed tumours in each region of the bowel correlates with the known incidence of tumours in each region and with a normal Dukes stage distribution, except in the caecum where the number of missed lesions was higher than expected.

Aged↗
PubMed2001

Social information processing in adolescents: data from normally developing adolescents and preliminary data from their peers with traumatic brain injury.

OBJECTIVE: To assess aspects of social information processing in naturalistic conversations, using online videotape tasks. DESIGN AND PARTICIPANTS: The tasks were administered to 60 normally developing (ND) subjects ages 13 to 21, and 10 adolescents with traumatic brain injury (TBI). SETTING: University. MAIN OUTCOME MEASURE: Task accuracy scores and measures of reliability and validity. RESULTS AND CONCLUSIONS: ND group scores were generally high, without significant differences by race, sex or age. TBI group scores were significantly lower than ND group scores for both emotion recognition and detection of conversation skills. The results are discussed in light of the evaluation of pragmatic competence in adolescents with TBI.

Adolescent↗
PubMed2001

Key factors in determining a dental practice site.

There is no single "right" place to place a dental practice. Personal preferences, family, friends, church, and recreation all have a hand in determining a dentist's likelihood of happiness with a particular location. Still, the science of demographics and psychographics (who people are and what they do) can provide a dentist with necessary insights into knowing the potential of a location. This article discusses important demographic and psychographic information that should be considered when determining a dental practice site.

California↗
PubMed2000

Measurement of pi(0)pi(0) production in the nuclear medium by pi(-) interactions at 0.408 GeV/c.

We report on an investigation of the (pi(-),pi(0)pi(0)) reaction by means of measurements of the pi(0)pi(0) invariant mass distributions from pi(-) interactions on H, D, C, Al, and Cu targets at p(pi(-)) = 0.408 GeV/c. The sharp, strong peak in the pi(+)pi(-) invariant mass near 2m(pi) reported by the CHAOS Collaboration is not seen in our pi(0)pi(0) data. However, we do observe a change in the shape of the pi(0)pi(0) invariant mass spectrum for the different targets, indicating that the pi(0)pi(0) interaction diminishes in the nuclear medium as represented by nuclei D, C, Al, and Cu, compared to hydrogen.

Journal Article↗
PubMed2000

Exploring the cognitive basis of right-hemisphere pragmatic language disorders.

Despite considerable interest in the linguistic dimensions of right-hemisphere (RH) pragmatic language disorders, the cognitive bases for these are rarely examined. This study investigated two alternative explanations. First, RH pragmatic language disorders may reflect failure of the RH to synthesise incoming and preexisting information, verbal and visuospatial. In this case language and visuospatial performance should covary. Alternatively such disorders may reflect damage to executive control of all cognitive processing secondary to frontal system failure. In this case language and executive function would be associated. Further, in the former case, subjects should be insensitive to the plausibility of information, whereas in the latter they would be fixated by the literal meaning of information and therefore highly sensitive to plausibility. Eighteen patients with RH damage were compared to 20 matched controls on a range of language and neuropsychological tasks. Pragmatic performance was generally correlated to RH (visuospatial) function, not to executive function. Nonetheless RH patients were found to have problems ignoring plausibility. Thus the specific RH hypothesis described needs to be reconsidered.

Adult↗
PubMed2000

Search for the CP forbidden decay eta-->4pi(0)

We report the first determination of the upper limit for the branching ratio of the CP forbidden decay eta-->4pi(0). No events were observed in a sample of 3.0x10(7) eta decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated pi(-) beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B(eta-->4pi(0))</=6. 9x10(-7).

Journal Article↗
PubMed2000

Ligand responsiveness in human prostate cancer: structural analysis of mutant androgen receptors from LNCaP and CWR22 tumors.

Androgen receptors (ARs) belong to the family of hormone receptors that are ligand-dependent transcription factors. Endocrine therapy provides effective treatment for prostate cancer until mutations arise that alter the ligand responsiveness of AR. In this study, structural models were developed for the functional domains of human AR by homology modeling from crystal structures of closely related nuclear receptors. These models were used to locate the sites of two frequently occurring mutations in prostate cancer. The substitutions that develop in LNCaP (threonine-->alanine at residue 877) and CWR22 (histidine-->tyrosine at residue 874) tumor cell lines are both located on helix 11 that forms part of the ligand-binding pocket. However, the results suggest that these mutations influence ligand responsiveness by completely different mechanisms. Residue 877 contacts the ligand directly, and substitution at this site alters the stereochemistry of the binding pocket. Thus, the LNCaP mutation apparently broadens the specificity of ligand recognition. In contrast, residue 874 is located down the helical axis, projects away from the ligand pocket, and does not contact ligand. The side chain of residue 874 lies in a cavity between helices 11 and 12. Substitution of tyrosine for histidine 874 in CWR22 tumors may affect a conformational change of helix 12 and, thus, influence binding of coactivator proteins and their regulatory effect on transcriptional activation.

Amino Acid Sequence↗
PubMed2000

Active versus expectant management in the third stage of labour.

BACKGROUND: Expectant management of the third stage of labour involves allowing the placenta to deliver spontaneously or aiding by gravity or nipple stimulation. Active management involves administration of a prophylactic oxytocic after delivery, early cord clamping and cutting, and controlled cord traction of the umbilical cord. OBJECTIVES: The objective of this review was to assess the effects of active versus expectant management on blood loss, post partum haemorrhage and other maternal and perinatal complications of the third stage of labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register. SELECTION CRITERIA: Randomised trials comparing active and expectant management of the third stage of labour in women with singleton pregnancies whose babies were presenting head first and who were expecting a vaginal delivery. DATA COLLECTION AND ANALYSIS: Trial quality was assessed and data were extracted independently by the reviewers. MAIN RESULTS: Four studies were included. Three of the trials were of good quality. Compared to expectant management, active management (in the setting of a maternity hospital) was associated with the following reduced risks: maternal blood loss (weighted mean difference -79.33 millilitres, 95% confidence interval -94.29 to -64. 37); post partum haemorrhage of more than 500 millilitres (odds ratio 0.34, 95% confidence interval 0.28 to 0.41); prolonged third stage of labour (weighted mean difference -3.40 minutes, 95% confidence interval -4.66 to -2.13). Active management was associated with an increased risk of maternal nausea (odds ratio 1. 95, 95% confidence interval 1.58 to 2.42), vomiting and raised blood pressure (probably due to the use of ergometrine). No advantages or disadvantages were apparent for the baby. REVIEWER'S CONCLUSIONS: Routine 'active management' is superior to 'expectant management' in terms of blood loss, post partum haemorrhage and other serious complications of the third stage of labour. Active managment is, however, associated with an increased risk of unpleasant side effects (eg nausea and vomiting), and hypertension, where ergometrine is used. Active management should be the routine management of choice for women expecting a single baby by vaginal delivery in a maternity hospital. The implications are less clear for other settings including domiciliary practice (in developing and industrialised countries).

Delivery, Obstetric↗
PubMed2000

Prophylactic syntometrine versus oxytocin for delivery of the placenta.

BACKGROUND: The routine prophylactic administration of an oxytocic agent is an integral part of active management of the third stage of labour. These agents help prevent postpartum haemorrhage. OBJECTIVES: The objective of this review was to assess the effects of ergometrine-oxytocin (syntometrine) with oxytocin alone in reducing the risk of postpartum haemorrhage (blood loss of equal to or greater than 500 millilitres) and other maternal and neonatal outcomes. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register. SELECTION CRITERIA: Trials of oxytocic drugs (syntometrine or oxytocin) in women having the third stage of labour managed actively. DATA COLLECTION AND ANALYSIS: Eligibility, trial quality assessment and data extraction were done independently by three reviewers. Study authors were contacted for additional information. MAIN RESULTS: Six trials were included. Compared with oxytocin, ergometrine-oxytocin (syntometrine) was associated with a small reduction in the risk of postpartum haemorrhage (odds ratio 0.74, 95% confidence interval 0.65 to 0.85). This advantage was smaller but still significant when 10 international units of oxytocin was used. There was no difference seen between the groups using either five or 10 international units for blood loss equal to or greater than 1000 millilitres. Adverse effects of vomiting and hypertension were associated with the use of ergometrine-oxytocin. No significant differences were found in other maternal or neonatal outcomes. REVIEWER'S CONCLUSIONS: The use of the combination preparation syntometrine (oxytocin and ergometrine) as part of the routine active management of the third stage of labour appears to be associated with a statistically significant reduction in the risk of postpartum haemorrhage when compared to oxytocin where blood loss is less than 1000ml. No difference was seen between the groups using either five or 10 international units for blood loss equal to or greater than 1000 millilitres. This needs to be weighed against the more common adverse effects associated with the use of syntometrine.

Ergonovine↗
PubMed2000

Cognitive impairment among methadone maintenance patients.

AIMS: To compare the cognitive performance of methadone maintenance patients (MMPs) and a matched sample of non-heroin-using control subjects, and to ascertain risk factors for poorer cognitive performance. DESIGN: Matched control study. SETTING: Sydney, Australia. PARTICIPANTS: Thirty MMPs and 30 non-heroin using controls, matched for age, gender and education. FINDINGS: The MMP group had significantly higher rates than controls of alcohol dependence, heroin overdose and head injury. There was no difference between the groups on pre-morbid functioning. The MMP group performed significantly poorer than controls on all of the neuropsychological domains measured: information processing, attention, short-term visual memory, delayed visual memory, short-term verbal memory, long-term verbal memory and problem solving. A life-time diagnosis of alcohol dependence and the number of non-fatal heroin overdoses were independent significant predictors of poorer cognitive performance. CONCLUSIONS: In addition to high rates of psychiatric morbidity, MMPs also show cognitive deficits compared to matched controls. A history of alcohol dependence and repeated exposure to overdose increase the likelihood of cognitive impairment. The current study does not rule out the possibility of other factors, that were not measured, that may contribute to cognitive impairment among this MMPs.

Adult↗
PubMed2000

Body mass index in aboriginal Australians in remote communities.

OBJECTIVES: To describe the distribution of body mass index (BMI) and estimate the prevalence of potential chronic energy deficiency (CED) and obesity in Aborigines in remote communities (ARC) in the Top End of the Northern Territory, Australia. METHODS: Centile charts were constructed for BMI from 1,631 sets of measurements from 1,138 Aborigines, aged five to 77 years, in three remote communities on the Tiwi Islands, using Cole's LMS method. These were compared with European, American white and American black reference charts. The prevalences of CED and obesity were also compared to the corresponding values from a national Indigenous sample. RESULTS: The BMI centiles change with age. Compared with reference populations, BMIs are lower in ARC children and adult males. Young adult females have similar BMIs to American black and higher BMIs than American white and French counterparts up to 45 years. Aborigines older than 50 years are 'thinner'. Compared with a national sample of Indigenous Australians, our sample has a higher prevalence of CED and a lower prevalence of obesity. CONCLUSIONS: The BMI centile curves describe the contemporary nutritional status in the remote communities. Nutritional status measured by BMI is different in ARC than in other populations. IMPLICATIONS: The difference in nutritional status between ARC and other populations should be considered when planning nutritional intervention strategies. The centile charts will allow health workers to determine the relative ranking of BMI for individual Aborigines in the remote communities.

Adolescent↗
PubMed2000

Detection of Francisella tularensis in biological specimens using a capture enzyme-linked immunosorbent assay, an immunochromatographic handheld assay, and a PCR.

The early detection of Francisella tularensis, the causative agent of tularemia, is important for adequate treatment by antibiotics and the outcome of the disease. Here we describe a new capture enzyme-linked immunosorbent assay (cELISA) based on monoclonal antibodies specific for lipopolysaccharide (LPS) of Francisella tularensis subsp. holarctica and Francisella tularensis subsp. tularensis. No cross-reactivity with Francisella tularensis subsp. novicida, Francisella philomiragia, and a panel of other possibly related bacteria, including Brucella spp., Yersinia spp., Escherichia coli, and Burkholderia spp., was observed. The detection limit of the assay was 10(3) to 10(4) bacteria/ml. This sensitivity was achieved by solubilization of the LPS prior to the cELISA. In addition, a novel immunochromatographic membrane-based handheld assay (HHA) and a PCR, targeting sequences of the 17-kDa protein (TUL4) gene of F. tularensis, were used in this study. Compared to the cELISA, the sensitivity of the HHA was about 100 times lower and that of the PCR was about 10 times higher. All three techniques were successfully applied to detect F. tularensis in tissue samples of European brown hares (Lepus europaeus). Whereas all infected samples were recognized by the cELISA, those with relatively low bacterial load were partially or not detected by PCR and HHA, probably due to inhibitors or lack of sensitivity. In conclusion, the HHA can be used as a very fast and simple approach to perform field diagnosis to obtain a first hint of an infection with F. tularensis, especially in emergent situations. In any suspect case, the diagnosis should be confirmed by more sensitive techniques, such as the cELISA and PCR.

Antibodies, Monoclonal↗
PubMed2000

Where to put a practice: factors to consider.

The temple of the Oracle at Delphi has "Know Thyself" engraved above it. Using modern demographic and psychographic research, it is both possible and practical to "know thy practice site" so that this important and risk-filled decision can be made rationally.

Demography↗
PubMed1999

Apparent bioaccumulation of Mn derived from paper-mill effluent by the freshwater crayfish Cherax destructor--the role of Mn oxidising bacteria.

Bioaccumulation studies of wastewater from a thermo-mechanical paper mill using the freshwater crayfish (Cherax destructor) consistently demonstrated elevated levels of manganese. Most of the Mn appeared to be associated with the carapace of the animals. It is suggested that the elevated Mn levels are the result of Mn-oxidising bacteria forming biofilms on the carapace of the crayfish followed by Mn oxide precipitation rather than active uptake of Mn by the crayfish.

Animals↗
PubMed1999

Subcellular localisation of NS3 in HCV-infected hepatocytes.

Hepatitis C virus (HCV) NS3 is a multifunctional protein with both protease and helicase activities and has been shown to interact with host cell proteins. It is shown that NS3 is present in the hepatocytes from patients with chronic HCV infection by using anti-NS3 antisera. NS3 is detectable in approximately 4% of the hepatocytes from these patients. In most infected cells, NS3 is present in the cytoplasm; however, in a minority of HCV-infected cells, both the cytoplasm and the nucleus or the nucleus on its own are positive for NS3. The presence of NS3 in the nuclei of hepatocytes in chronically infected patients indicates that the protein may play a role other than in virus replication, such as in persistence of HCV infection.

Blotting, Western↗