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Biomedical subjects

P J Stewart

Publications and source records attributed to P J Stewart.

At least 19 recordsLinked to original sources
PubMed1993

The need for a community-wide approach to promote healthy babies and prevent low birth weight.

A community-wide approach offers a potentially more effective way to promote healthy babies in healthy families and to prevent low birth weight. It can address the many factors associated with preterm birth and intrauterine growth restriction, the need to include all members of the community in effecting meaningful change in the incidence rate of adverse outcomes and the development of an effective mechanism to plan and coordinate the delivery of programs. Physicians have an essential role to play in this approach. The evaluation of such a program would complement current biomedical research on the prevention of preterm birth and intrauterine growth restriction. The work for this paper was supported by the Community Health Research Unit, funded by the Ontario Ministry of Health.

Community Health Services↗
PubMed1993

Intra-operative ultrasound for the detection of hepatic metastases from colorectal cancer.

The aim of this study was to compare the accuracy of intra-operative ultrasound (IOUS) with other imaging modalities and with surgical palpation in detecting liver metastases from colorectal cancer (CRC). Intra-operative ultrasound was performed in 100 patients undergoing surgery for CRC. All patients had pre-operative liver function tests, transcutaneous ultrasound and computerized tomography (CT) scan of the liver. The liver was palpated intra-operatively by a surgeon who was unaware of the pre-operative findings. The liver was then assessed by IOUS. Intra-operative ultrasound detected more patients with metastases than either CT scan, transcutaneous ultrasound or surgical palpation. It also detected a greater number of smaller metastases in these patients and allowed better anatomical definition compared with pre-operative investigations.

Adult↗
PubMed1991

Parathyroid hormone (1-34) and Nleu8,18Tyr34-parathyroid hormone, (3-34) amide increase diacylglycerol in neonatal mouse calvaria.

Previously, we and others have presented evidence that a calcium second messenger system is involved in the action of parathyroid hormone (PTH) on bone. In the present report, the effects of PTH(1-34) and PTH(3-34)amide treatment on diacylglycerol (DG) in neonatal mouse calvaria are described. PTH(1-34) produced a rapid (within 5 minutes) increase in calvarial incorporation of 3H-arachidonic acid into DG. The effect was maximal at 0.1 nMPTH(1-34), the lowest concentration tested. The 3-34 amide analogue of PTH increased DG to the same extent as PTH(1-34). The effect was maximal at 10 nM PTH(3-34)amide, the lowest concentration tested. These concentrations were lower than those required to elicit maximal effects on bone resorption. In contrast to effects on cyclic AMP, where the 3-34 amide inhibited the increase elicited by PTH, combined treatment of calvaria with PTH(1-34) and PTH(3-34)amide did not inhibit effects on resorption or diacylglycerol.

Animals↗
PubMed1991

Complications following closure of loop ileostomy.

The morbidity and mortality of 50 patients undergoing closure of loop ileostomy was reviewed. The patients had a mean age of 57.9 years and significant intercurrent disease. There were no in-hospital deaths or anastomotic leakage at the site of closure. Small bowel obstruction occurred in 12% of patients, all of whom responded to conservative treatment. The wound infection rate was 14%, but the development of a wound infection did not result in a significantly longer hospital stay. We conclude that, when a careful technique of sharp dissection is used, closure of a loop ileostomy is associated with an acceptably low incidence of complications even in elderly and often unwell patients.

Adolescent↗
PubMed1991

Frequency of intermediate admissions and place of death of patients with advanced colorectal cancer.

An analysis was made of the place of death and the degree of institutional support required following surgery in patients with colorectal cancer (CRC) who had distant metastases. There was a high incidence of intermediate admissions to an acute hospital, and most patients died in an acute hospital bed. The number of readmissions and the place of death were not influenced by the patients' age, sex, site of tumour or their home situation at the time of diagnosis. In view of the high demand for acute surgical beds, there is a need to develop more appropriate facilities to care for patients in the terminal phase of this disease.

Aged↗
PubMed1990

Interest in alternative birthplaces among women in Ottawa-Carleton.

Birthing rooms, birth centres and home birth have been proposed as alternatives to the traditional in-hospital caserooms to meet the needs of women and their families more effectively. We performed a descriptive survey to determine the level of interest of childbearing women in the Ottawa-Carleton region in these birthplaces and to examine the characteristics of women who express an interest in using them. Of the 1629 women who gave birth between July 1 and Aug. 28, 1987, 1115 (68.4%) completed a self-administered questionnaire during the pregnancy, in the early postpartum period in hospital or at home. Of the respondents 577 (53.1%) said they would choose the caseroom, 316 (29.1%) the birthing room, 165 (15.2%) the birth centre and 30 (2.8%) home birth. The women who expressed an interest in a birthplace other than the caseroom were more likely than the others to be older, married, well-educated and interested in midwifery services and to breastfeed their babies (p less than 0.05). They were also more likely to have had a low-intervention vaginal birth (p less than 0.05). The interest expressed in birthing rooms, birth centres and home birth suggests that these alternatives should be considered for inclusion in the health care system.

Adolescent↗
PubMed1990

Diagnosis of dystocia and management with cesarean section among primiparous women in Ottawa-Carleton.

We carried out a chart review study to determine the rate of diagnosis of dystocia (abnormal progress) and the use of cesarean section to treat dystocia among 3887 primiparous women who gave birth to a single baby in the vertex presentation at four hospitals in Ottawa-Carleton in 1984. Of the 3740 women who had some labour 1127 (30.1%) were given a diagnosis of dystocia. Cesarean section for dystocia was done during all phases of labour (41% of procedures in the latent phase, 38% in the active phase and 21% in the second stage). The cesarean section rate varied among the hospitals from 11.8% to 19.6%. A total of 75% of the cesarean sections were for dystocia, disproportion or failed induction. The findings suggest that cesarean section is being done for disproportion without a trial of labour beyond the latent phase and for dystocia in the absence of fetal distress. If these practices were modified the cesarean section rate could be reduced from 16% to about 8%, the rate found in some other centres and that observed in Canada in the early 1970s.

Adult↗
PubMed1990

Midwifery in Ontario: a survey of interest in services.

Maternity care for women in Ontario is provided almost exclusively by physicians, the majority of whom are obstetricians. Using a self-administered questionnaire, pregnant women in one Ontario city were surveyed about their interest in midwifery care as an alternative to physician care. Although 3 percent of the women surveyed had used a midwife, 60 percent expressed an interest in midwifery care, particularly the counseling and support aspects. Over 11 percent showed an interest in complete primary midwifery care.

Attitude to Health↗
PubMed1989

Cyclosporines: correlation of immunosuppressive activity and inhibition of bone resorption.

Cyclosporine A (CsA) is a potent immunosuppressive agent that inhibits stimulated bone resorption in vitro. To study the mechanism of this effect, we have compared CsA with several cyclosporine analogs that vary in immunosuppressive potency. CsA as well as another potent immunosuppressive analog, CsG, inhibited parathyroid hormone (PTH) and interleukin-1 (IL-1)-stimulated resorption of fetal rat limb bones. The nonimmuno-suppressive analogs CsH and CsF did not inhibit PTH or IL-1-stimulated bone resorption. Likewise, the weakly immunosuppressive analog CsD did not significantly inhibit PTH-stimulated bone resorption. Although other mechanisms cannot be excluded, our data are consistent with the concept that bone resorption may involve an immune cell-derived mediator.

Animals↗
PubMed1989

Interaction of cyclosporine A and calcitonin on bone resorption in vitro.

Cyclosporine A (CsA), which is a potent immunosuppressive agent, inhibits bone resorption in vitro. The inhibition of bone resorption by CsA is sustained, unlike the transient inhibition of bone resorption produced by calcitonin (CT). These different patterns of inhibition were studied by examining the interaction between CsA and CT on stimulated bone resorption in the neonatal mouse calvarial resorptive system. "Escape" from the CT inhibition of PTH stimulated bone resorption occurred after 24 hr of organ culture. Coincubation with CsA (1 micrograms/ml) delayed the "escape" response of CT + PTH treated bones, so that the full "escape" response did not occur until after 48 hr of organ culture. Likewise, a pretreatment of 24 hr with CsA (1 micrograms/ml) was sufficient to delay "escape" from CT inhibition of PTH stimulated bone resorption until after 48 hr of organ culture. A higher concentration of CsA (10 micrograms/ml) completely prevented the "escape" response. Our data could indicate an interaction between the CsA and CT inhibitory effects on resorption.

Analysis of Variance↗
PubMed1988

Opinions of physicians assisting births in Ottawa-Carleton about the licensing of midwives.

The Ontario Ministry of Health announced in January 1986 that midwives would be licensed to practise in Ontario. In September of that year we surveyed all physicians in Ottawa-Carleton who were assisting at births to determine their opinions on midwifery. A total of 78 (74%) of the eligible physicians completed the questionnaire. Almost half thought that midwives should be licensed. Most felt that midwives should be trained as nurses first and should work under the supervision of a physician in hospital-based clinics or in a group practice with physicians. A small proportion thought that midwives should be able to practise as independent practitioners. Some obstetricians thought that legalization of midwifery would allow them to concentrate on high-risk obstetrics, and some family physicians thought this would make it easier for them to continue to be involved in maternity care. Those opposed to the introduction of midwives did not think the public would benefit, and some were concerned that midwives would reduce the size of their own obstetric practices.

Attitude of Health Personnel↗
PubMed1988

Influence of relative humidity on the adhesive properties of a model interactive system.

The influence of relative humidity on the adhesive properties of model drug-carrier interactive systems was investigated using the centrifuge method. The degree of adhesion was quantified by determining the S50 from the adhesion profile. High ambient humidity (greater than 40% r.h.) decreased the degree of interaction of three sulphonamide powders with model hydroxypropyl methylcellulose phthalate-coated glass bead carriers during blending. All drug-carrier interactive systems displayed decreases in the degree of adhesion during storage. The extent and rate of the decreases increased with relative humidity and was interactive system-dependent. Preconditioning the powders to varying moisture contents produced contrasting results during blending, with one system showing a decrease in adhesion as the relative humidity increased, while the other's interactive capability increased. This increase was attributed to the enhancement of charging sites on the drug's powders surface by the adsorbed moisture.

Adsorption↗
PubMed1987

Calcium/phosphatidylserine-stimulated protein phosphorylation in bone: effect of parathyroid hormone.

The calcium/phosphatidylserine (PS)-stimulated phosphorylation of endogenous proteins in the 100,000 x g particulate fraction from neonatal mouse calvaria was investigated. EGTA selectively inhibited the phosphorylation of a 20K protein. The phosphorylation of this 20K protein was stimulated by calcium and by PS. The combination of calcium plus PS increased the phosphorylation of the 20K protein more markedly than either calcium or PS alone. Parathyroid hormone (PTH) (100 nM) treatment of calvaria rapidly altered the phosphorylation of the 20K protein in a time-dependent manner. The PTH treatment time course demonstrated that after 5 minutes the in vitro phosphorylation of the 20K protein was markedly enhanced, after 15 minutes the 20K protein was not as heavily phosphorylated, and after 30 minutes the in vitro phosphorylation of the 20K was less than control. Our results demonstrate the presence of calcium/PS-stimulated phosphorylation in bone tissue and a rapid effect of PTH on this phosphorylation.

Animals↗
PubMed1987

Vertebral bone resorption in vitro: effects of parathyroid hormone, calcitonin, 1,25 dihydroxyvitamin D3, epidermal growth factor, prostaglandin E2, and estrogen.

We have developed and characterized a new bone resorption system to test the effect of estrogen on vertebral bone in vitro. Neonatal mouse vertebral bones prelabeled with 45Ca were maintained in stationary tissue culture for 60-108 hours at 37 degrees C in 5% CO2/air. Each vertebral bone measured approximately 1 mm X 1 mm. Hormonal treatments were added directly to the incubation medium. The morphological appearance of these bones, before and after the onset of resorption, was examined by scanning electron microscopy. Bone resorption was measured by determining the % of the bone 45Ca released into the incubation medium. Vertebral bone resorption was stimulated in a dose-dependent manner by parathyroid hormone (1-100 nM), 1,25 dihydroxyvitamin D3 (0.0325-3.25 nM), and prostaglandin E2 (3-3000 nM). Epidermal growth factor (300 ng/ml) produced a small stimulation of bone resorption which was not inhibited by indomethacin (0.5 microM). Likewise, indomethacin (0.5 microM) did not inhibit PTH-stimulated vertebral bone resorption. Calcitonin (6.6 nM) produced a 79% inhibition of bone resorption induced by PTH (10 nM), whereas estradiol (up to 3 microM) did not inhibit bone resorption. Our results demonstrate that estrogen does not have a direct effect on vertebral bone tissue in vitro. This new bone culture system is a sensitive assay for the direct effects of resorptive agents on vertebral bone.

Animals↗
PubMed1987

The effect of particle size and concentration on the adhesive characteristics of a model drug-carrier interactive system.

The effect of concentration and particle size on the adhesive tendency of drug particles in a model interactive system was investigated using a centrifuge technique. The model interactive system consisted of drug powders adhered to coated glass carrier beads. Adhesion profiles of per cent of drug remaining on the carrier versus the square of the speed of rotation were a logarithmic normal function. Increase in the adherent particle size and concentration decreased the adhesive tendency of all drug powders studied. Particle collisions during detachment and the formation of multiparticulate layers even before the monolayer saturation of the carrier surface were responsible for the reduced adhesive stability of the drugs on the carrier as the particle loading increased.

Adhesiveness↗
PubMed1987

The effect of blending time on particle adhesion in a model interactive system.

The adhesive tendency of drug particles in a model drug carrier interactive system increased with blending time. The degree of interaction was measured using a centrifuge technique; the resultant adhesion profile of per cent retained on the carrier versus the square of the speed of rotation was a logarithmic normal function that allowed the determination of the S50 to characterize the adhesion tendency. The relative degree of adhesion of the drug particles in the interactive mixtures and the rate to attain adhesion saturation in the interactive system during the mixing process was markedly different for the three mixtures studied. The increased adhesive tendencies during blending were probably associated with triboelectrification of the drug and carrier particles.

Adhesiveness↗