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Biomedical subjects

R Welch

Publications and source records attributed to R Welch.

At least 37 records · Page 2Linked to original sources
PubMed1995

General practitioner obstetric practice in rural and remote Western Australia.

The objective of this study was to examine the practice of obstetrics by general practitioners in rural and remote areas of Western Australia (WA). A questionnaire was mailed to all rural and remote GPs in June, 1994. The response rate was 67%. Questionnaires asked GPs to self-report how many deliveries they had performed in the previous year and how many of those deliveries were by Caesarean section or assisted by forceps or ventouse. Comparisons were made with perinatal statistics for the entire State of WA. GPs reported an average of 28 deliveries per year. The Caesarean section rate of 8% was lower than the rate of 21% for all WA in 1993. Ventouse was used more often than forceps to assist the delivery of a baby. Intervention rates for ventouse, forceps and Caesarean section were lower in rural and remote areas of WA than the State as a whole; there was also less use of epidural analgesia. More than half of these GPs currently practising obstetrics hold the Dip RACOG or DRCOG. Medical indemnity is an increasing issue for many GPs. For 6 of the 7 country health regions, close to 80% of women deliver within the health region in which they reside.

Delivery, Obstetric↗
PubMed1995

Identification and characterization of an outer membrane protein, OmpX, in Escherichia coli that is homologous to a family of outer membrane proteins including Ail of Yersinia enterocolitica.

We previously reported that a region of the Escherichia coli chromosome at 18 min increased E sigma E activity when cloned in multicopy (J. Mecsas, P. E. Rouviere, J. W. Erickson, T. J. Donohue, and C. A. Gross, Genes Dev. 7:2618-2628, 1993). In the present report, we identify and characterize the gene responsible for the increase in E sigma E activity. This gene is in a monocistronic operon with two promoters and a rho-independent terminator. Sequence analysis of this gene indicated that it encodes an outer membrane protein which is 83% identical to OmpX in Enterobacter cloacae, leading us to name this gene ompX. There are four other proteins that are homologous to OmpX. Several of these proteins, Ail of Yersinia enterocolitica and Rck and PagC of Salmonella typhimurium, have properties that allow bacteria to adhere to mammalian cells, survive exposure to human serum, and/or survive within macrophages. We therefore characterized strains deleted for ompX for their growth phenotypes, E sigma E activity, serum resistance, and adherence to mammalian cells. No differences in growth rates, serum resistance, or adherence to mammalian cells were observed; however, E sigma E activity was dependent on expression of OmpX in certain strain backgrounds.

Amino Acid Sequence↗
PubMed1994

Pore-formation by Escherichia coli hemolysin (HlyA) and other members of the RTX toxins family.

Escherichia coli hemolysin (HlyA) is a major cause of E. coli virulence. It lyses erythrocytes by a colloid osmotic shock due to the formation of hydrophilic pores in the cell wall. The size of these channels can be estimated using osmotic protectant of increasing dimensions. To show that the formation of pores does not depend critically on the osmotic swelling we prepared resealed human erythrocyte ghosts loaded with a fluorescent marker. When attacked by HlyA the internal marker was released, indicating the formation of toxin channels so large as to let it through. The channels can be directly demonstrated also in purely lipidic model systems such as planar membranes and unilamellar vesicles, which lack any putative protein receptor. HlyA has been recognised as a member of a large family of exotoxins elaborated by Gram-negative organisms including Proteus, Bordetella, Morganella, Pasteurella and Actinobacillus. These toxins have quite different target cell specificity and in many cases are leukocidal. When tried on planar membranes however, even specific leukotoxins open channels not dissimilar from those formed by HlyA, suggesting this might be a common step in their action. Comparison of the hydrophobic properties of six members of the toxin family indicates the presence of a conserved cluster of ten contiguous amphipathic helixes, located in the N-terminal half of the molecule, which might be involved in channel formation.

Bacterial Proteins↗
PubMed1994

Clinical utility of fetal RhD typing in alloimmunized pregnancies by means of polymerase chain reaction on amniocytes or chorionic villi.

OBJECTIVE: Our purpose was to describe the clinical utility of a deoxyribonucleic acid amplification method for determining fetal RhD status in alloimmunized pregnancies STUDY DESIGN: Six RhD-negative women with alloimmunized pregnancies and heterozygous partners underwent amniocentesis (n = 5) or chorionic villus sampling (n = 1). Fetal RhD type was determined by polymerase chain reaction and results disclosed to the attending physicians. RESULTS: Knowledge of the fetal RhD status avoided further invasive procedures in two pregnancies and facilitated the timing or performance of intrauterine transfusions in the remainder. CONCLUSIONS: In alloimmunized pregnancies the ability to RhD-type the fetus in amniotic fluid avoids the risks of fetomaternal hemorrhage and increased sensitization associated with fetal blood sampling or chorionic biopsy. This allows more rational pregnancy management, avoiding invasive procedures in the presence of an RhD-negative fetus, or planning therapeutic interventions or offering termination of pregnancy in the presence of an RhD-positive fetus.

Amniotic Fluid↗
PubMed1994

Changes in hemorheology with fetal intravascular transfusion.

OBJECTIVE: Our aim was to determine the changes in fetal hemorheologic parameters caused by fetal intravascular transfusion for alloimmune anemia. STUDY DESIGN: Fetal blood samples were collected before and after 95 fetal transfusions in 31 women. Fetal hematocrit, whole-blood viscosity at a variety of shear rates, plasma viscosity, fetal fibrinogen, and fetal plasma proteins were measured. RESULTS: Fetal whole-blood viscosity increased, sometimes massively, with transfusion. The rise in viscosity was principally dependent on the rise in hematocrit, with a linear rise in hematocrit producing a linear rise in the logarithm of whole-blood viscosity, but was also affected by the amount of adult plasma proteins present in the donor blood. CONCLUSIONS: Rises in fetal whole-blood viscosity during transfusion can be minimized by using donor blood that has been serum depleted to a high hematocrit (> 90%) and by restricting the end hematocrit to 50% to 55%.

Blood Proteins↗
PubMed1993

The cost-benefits of a nursing demonstration project, Part III.

The Milieu Enhancement Nursing project was funded for 3 years by the Division of Nursing, Department of Health and Human Services. One of the project goals was to perform a cost/benefit analysis of project activities. The conceptual framework and formulas used for data analysis are presented. The project was deemed successful, as data supported a favorable cost to benefit ratio.

Adolescent↗
PubMed1992

Recombinant human erythropoietin in patients with ovarian carcinoma and anaemia secondary to cisplatin and carboplatin chemotherapy: preliminary results.

Preliminary results from the first 21 patients of a group of 30 with International Federation of Gynaecology and Obstetrics (FIGO) stage II-IV epithelial ovarian carcinoma and anaemia are reported. Patients entered this open-label, comparative-group, out-patient study and were randomized to receive conventional support alone (control patients) or recombinant human erythropoietin (r-HuEPO) in addition to conventional support for 6 months. The aim of the study was to determine the effects of r-HuEPO on the anaemia induced by platinum-based chemotherapy. Patients randomized to r-HuEPO therapy received 300 U/kg subcutaneously 3 times weekly in addition to conventional chemotherapy. All patients underwent regular haematological monitoring. One patient developed a deep venous thrombosis after 17 doses of r-HuEPO; it was thought that this event may have been related to therapy and the patient was withdrawn from the study. Three other withdrawals occurred after 11, 15 and 40 doses of r-HuEPO because of progressive anaemia, metoclopramide-induced skin rash and change of chemotherapy, respectively. In the 21 patients analysed to date, there was a notable reduction in blood transfusion requirements during the 6 months of chemotherapy and an improvement in mean serial haemoglobin concentrations in patients on r-HuEPO compared with the control group. In conclusion, r-HuEPO has the potential for reducing haematological toxicity in patients with ovarian carcinoma receiving platinum-based chemotherapy. Also, r-HuEPO may allow modest dosage increments in chemotherapy or the addition of abdominopelvic radiotherapy.

Adult↗
PubMed1990

High-performance liquid chromatographic analysis of doxacurium, a new long-acting neuromuscular blocker.

A rapid and sensitive high-performance liquid chromatographic procedure was developed for the analysis of the new, long-acting neuromuscular blocker doxacurium in the plasma and urine of dog and man and in the bile of dog. Samples were prepared on solid-phase extraction cartridges containing a methyl (C1) bonded phase and were chromatographed on a 15 cm reversed-phase column (C1) using a mobile phase of 0.05 M monobasic potassium phosphate-acetonitrile (30:70, v/v). The compound was detected at 210 nm with a lower limit of quantitation of 10 ng/ml. An inter-assay accuracy of 90-92% was obtained for the analysis of the drug from biological fluids. The method was applied to studies of doxacurium after intravenous administration to dog and man.

Animals↗
PubMed1990

Serial magnetic resonance imaging in neonatal hypoxic-ischemic encephalopathy.

We prospectively performed magnetic resonance imaging (MRI) studies during the neonatal period, and at 4 and 8 months of age, on 15 term infants with hypoxic-ischemic encephalopathy, and compared the results with their neurodevelopmental outcome at 18 months of age. Cerebral palsy developed in nine infants, two infants were classified as having abnormalities of tone and delayed motor milestones that were suggestive of cerebral palsy, and four infants were normal. Structural abnormalities, delayed myelination, or a combination of the two were detected with MRI at 8 months of age in all nine infants with later development of cerebral palsy. Three of the four normal infants and one infant with suggestive abnormalities had normal serial MRI findings. Each of the remaining two infants (one normal, one with suggestive abnormalities) had isolated persistent ventricular dilation on all three MRI studies. Our results suggest that 8 months appears to be the earliest time at which MRI findings correlate well with later adverse neurodevelopmental outcome in this population.

Age Factors↗
PubMed1990

Mental health needs of the chronically mentally ill elderly.

The treatment histories and current social, financial, and clinical status of 111 chronically mentally ill (CMI) persons over the age of 60 were examined. Information was obtained from Ss, family, mental health records, and mental health professionals familiar with Ss. Psychiatric symptoms were observed in 74% of Ss. Many Ss experienced long periods without acute episodes of illness. Recurring episodes eventually appeared in most Ss, however, and ongoing deficits in daily functioning and social contacts were prototypical. Two thirds of the Ss were living in the community, relying heavily on family contacts; the rest lived primarily in nursing homes (23.4%) or psychiatric hospitals (7.2%). Social support was the best predictor of level of functioning. Findings suggest that failure of CMI elderly to use mental health services is not due to lack of need. Mental health services currently do not appear to be meeting the needs of this population.

Activities of Daily Living↗
PubMed1989

Determinants of polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), and dichlorodiphenyl trichloroethane (DDT) levels in the sera of young children.

Serum samples from 285 4-year-old Michigan children were evaluated for levels of 11 environmental contaminants. Polychlorinated biphenyls (PCBs) were found in half the samples tested; polybrominated biphenyls (PBBs) in 13-21 percent; dichlorodiphenyl trichloroethane (DDT), in more than 70 percent. Nursing (Mothers' milk) was the principal source of these exposures. Congener-specific analysis documented the presence of at least one highly toxic PCB congener, 2,3',4,4',5-pentachlorobiphenyl. The data demonstrate the multigenerational impact of female exposure to persistent organic environmental contaminants.

Body Burden↗
PubMed1989

Validity of messages from quadriplegic persons with cerebral palsy.

Interpreting gestures from retarded, nonvocal subjects is scientifically risky. Investigators must construe the subject's meaning without reference to an external validity measure. A procedure was devised in which message content was provided to nonvocal, severely palsied quadriplegic subjects in advance. Subjects' responses were limited to yes/no gestures. Another investigator elicited the messages without prior knowledge of their content. Results, which indicated reasonably high correspondence between stimulus messages and messages elicited, suggest that such subjects can present the content of their own phenomenal field accurately and that investigators' interpretations need not be considered imaginary.

Adult↗
PubMed1987

Toluidine blue in the corroboration of rape in the adult victim.

Objective physical evidence to corroborate a claim of rape is frequently absent. Genital lacerations are considered evidence that rape has occurred. In this study, toluidine blue dye, a nuclear stain, was used to detect vaginal lacerations. The detection of vaginal lacerations in reported rape victims increased from one in 24 to 14 in 24 with toluidine application. Toluidine blue increases the detection of perineal lacerations in adult rape victims and the presence of lacerations is supportive of the documentation of rape.

Adult↗