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Biomedical subjects

C Johnston

Publications and source records attributed to C Johnston.

At least 127 records · Page 7Linked to original sources
PubMed1996

New college data may shed light on issue of sexual abuse by physicians.

During a recent conference on physician health that was cosponsored by the CMA and American Medical Association, physicians learned that there had been an increase in the number of reported cases of abuse of patients by physicians in Ontario. The increase occurred after new legislation made the reporting of suspected sexual abuse mandatory in the province in 1994. Dr. Laurel Dempsey said there was "a considerable body of opinion" at the College of Physicians and Surgeons of Ontario that there would be a backlog of cases waiting to be reported once the new law took effect. However, it won't be possible to tell if this backlog actually exists until data have been gathered for at least a few more years.

Canada↗
PubMed1996

US ad uses lure of prompt treatment to entice Canadians needing joint replacement.

A Virginia hospital has used newspaper advertisements to solicit Ontario patients who are waiting for hip- or knee-replacement surgery. The ads promote the medical services of US orthopedic surgeons and call attention to exasperatingly long waiting lists for the same surgery in Canada. "Pain doesn't wait," they state. "Neither should you." The hospital says it has been receiving more than 100 calls a week inquiring about the procedure, which costs $15000 (US).

Advertising↗
PubMed1996

Scottish MDs benefit from database model developed in Saskatchewan.

A data-tracking system developed in Saskatchewan has helped health authorities in Scotland identify some deficiencies in the way certain drugs are prescribed and used. A researcher who published survey results in a local medical journal said the findings have helped doctors improve prescribing practices and identified a need to educate patients about the way antidepressant drugs work.

Computer Systems↗
PubMed1996

Comparison of nonrandomized trials with slow-release sodium fluoride with a randomized placebo-controlled trial in postmenopausal osteoporosis.

The results of slow-release sodium fluoride (SR-NaF) treatment in two nonrandomized trials involving 65 patients with postmenopausal osteoporosis from the primary site and 121 patients from collaborative sites were compared with those obtained from 54 treated patients and 56 patients taking placebo from a randomized controlled trial. Spinal fracture data were analyzed separately in mild to moderate bone loss of lumbar spine (baseline L2-L4 bone density [BD] > or = 65% young normal) and in severe bone loss (BD < 65%). Since demographic and fracture data were similar among fluoride-treated patients from the three trials at each stratum of bone loss, their data were combined. In mild to moderate bone loss, SR-NaF treatment in the combined group virtually eliminated new spinal fractures with 96.6% of patients remaining fracture-free. The Fluoride group had a markedly lower individual vertebral fracture rate (0.025 vs. 0.188/patient year, p = 0.0001) and group vertebral fracture rate (0.029 vs. 0.175/patient year, relative risk [RR] 0.12, p = 0.0001) than the Placebo group. In severe bone loss, the combined treated group had a significantly lower new spinal fracture rate than the Placebo group, although the differences were not as marked (group vertebral fracture rate of 0.150 vs. 0.276/patient year, RR 0.54, p = 0.03). In the combined fluoride-treated group, the L2-L4 bone mass rose by 4-6%/year for 4 years, and the femoral neck BD increased by 1-2%/year during first 2 years. The radial shaft BD did not change. The Placebo group did not show a change in bone mass at any site. The prevalence (percentage) of patients with related gastrointestinal side effects and nonvertebral fracture rates did not differ significantly between the combined SR-NaF group and the Placebo group (hip fracture rate of 0.0045/patient year in SR-NaF and 0.0053/patient year in Placebo; appendicular fracture other than hip (see text) rate of 0.0193/patient year in SR-NaF and 0.0159/patient year in Placebo). A subgroup analysis showed a low baseline L2-L4 BD, high prevalent spinal fractures, and reduced body weight to be important determinants of the development of spinal fracture during SR-NaF treatment. Concomitant medications (estrogen, vitamin D, thiazide and thyroid hormone) were not independent predictors of the spinal fracture risk. Only 17% of fluoride-treated patients were nonresponders (new spinal fractures or a fall/no change in L2-L4 bone mass). Thus, the effects of SR-NaF treatment on the spinal fracture rate from nonrandomized trials were similar to those of the treated group of the randomized trial but different from those of the Placebo group. The similarity of response of nonrandomized trials with that of the randomized controlled trial and the resultant combined analysis further validate the efficacy and safety of SR-NaF in the treatment of postmenopausal osteoporosis.

Bone Density↗
PubMed1996

Parent characteristics and parent-child interactions in families of nonproblem children and ADHD children with higher and lower levels of oppositional-defiant behavior.

This study examined parent-child interactions and parent characteristics in families of nonproblem children and attention deficit hyperactivity disorder (ADHD) children with lower (ADHD-LOD) and higher (ADHD-HOD) levels of oppositional-defiant behavior. Families of ADHD children were recruited from a parent training program. Observed and parent-reported child behavior problems were highest in the ADHD-HOD group. Observed parent behavior revealed few differences, but daily reports indicated that parents in both ADHD groups used more negative-reactive and fewer positive parenting strategies than control parents. Maternal psychological functioning differed between the ADHD and nonproblem groups, but not between the two ADHD groups. Fathers of ADHD-HOD children reported more psychological disturbance than controls. Parenting self-esteem was lowest in the ADHD-HOD group and highest in the nonproblem group. The results support the LOD and HOD distinction, but also suggest that, although certain difficulties are more common in the families of ADHD-HOD children, families of ADHD-LOD children also differ from controls on a number of dimensions.

Adult↗
PubMed1996

High risk of lymphomas in children of Asian origin: ethnicity or confounding by socioeconomic status?

To examine the role of ethnic origin as a risk factor for paediatric lymphoma, a cancer registry-based analysis was undertaken in Yorkshire, UK. Children of Asian ethnic origin were found to have an odds ratio for lymphomas of 1.60 (CI 0.98-2.62), after adjusting for age and sex. After adjusting also for 'super profile group' as an indicator of socioeconomic status, the estimate became 1.99 (CI 1.08-3.68). Hodgkin's disease and non-Hodgkin's lymphomas were analysed separately with similar results. Super profile group is an area-based measure and may not reflect the individual variation in living standards, especially among the Asian immigrants. Our results indicate that socioeconomic status does not confound the relationship between lymphomas and ethnic origin. However, there is a need for studies of ethnicity that include indicators of individual living standards or socioeconomic status.

Adolescent↗
PubMed1996

Transcriptional activation of Salmonella typhimurium invasion genes by a member of the phosphorylated response-regulator superfamily.

The Salmonella typhimurium PhoP-repressed locus prgHIJK encodes components of a sec-independent type III secretion apparatus. This apparatus is composed of at least 17 proteins encoded on a 40 kb pathogenicity Island located at centisome 63 on the S. typhimurium chromosome. The secretion apparatus and some of its targets, SapB, SapC and SspD, are necessary for epithelial cell invasion. The transcription of many invasion genes, including prgHIJK, is coordinately activated by HilA, a transcription factor encoded within the pathogenicity island. In this report we identify sirA, a gene located outside the pathogenicity island that is essential for induction of prgHIJK and hilA transcription. sirA encodes a 234-amino-acid protein that is essential for S. typhimurium Ssp (Salmonella secreted protein) secretion and invasion and is similar to response regulators of two-component regulatory systems. sirA-mutant phenotypes could be suppressed by two DNA clones from unlinked loci, designated sirB and sirC. These data suggest that SirA may be phosphorylated in response to S. typhimurium sensing a mammalian microenvironment. Furthermore, SirA phosphorylation is predicted to initiate a cascade of transcription-factor synthesis which results in invasion-gene transcription, Ssp secretion, and bacterial invasion of epithelia.

Amino Acid Sequence↗
PubMed1996

Premature Infant Pain Profile: development and initial validation.

OBJECTIVE: Inadequate assessment of pain in premature infants is a persistent clinical problem. The objective of this research was to develop and validate a measure for assessing pain in premature infants that could be used by both clinicians and researchers. DESIGN: The Premature Infant Pain Profile (PIPP) was developed and validated using a prospective and retrospective design. Indicators of pain were identified from clinical experts and the literature. Indicators were retrospectively tested using four existing data sets. PATIENTS AND SETTINGS: Infants of varying gestational ages undergoing different painful procedures from three different settings were utilized to develop and validate the measure. METHODS AND RESULTS: The largest data set (n = 124) was used to develop the PIPP. The development process included determining the factor structure of the data, developing indicators and indicator scales and establishing internal consistency. The remaining three data sets were utilized to establish beginning construct validity. CONCLUSIONS: The PIPP is a newly developed pain assessment measure for premature infants with beginning content and construct validity. The practicality and feasibility for using the PIPP in clinical practice will be determined in prospective research in the clinical setting.

Gestational Age↗
PubMed1996

Kinematics of the distal hindlimb during stance phase in the fast trotting standardbred.

Fast trotting Standardbred horses were filmed along a straight on an oval dirt track. Five consecutive stance phases were analysed to describe the planar kinematics of the distal hindlimb. The rapid changes in the geometry of the distal hindlimb that occur during the early stance phase were studied. The hoof segment was initially braked vertically and moved in the direction of the horse. The hoof moved forward on the track surface for more than 20% of the stance time (ST). Two specific deviations in the otherwise smooth course of the fetlock joint angle appeared at 16 and 29% of ST. Tarsal angular joint displacement was, on the other hand, more smooth throughout the stance phase. Segment angular velocity was greatest in the proximal pastern segment, while the metatarsus was almost totally braked in its forward rotation during the early stance. Tibial angular velocity was more smooth and greater than that of the metatarsus. Initial vertical braking of the hoof was related to the rapid rotation of the proximal pastern segment, while the metatarsal and proximal pastern segment angular velocities decreased as the hoof was braked horizontally. Also coincident with horizontal braking of the hoof was an increase in the angular velocity of the tibial segment. It was concluded that the horizontal as well as the vertical braking of the hoof affect the disto-proximal braking of the segments of the distal hindlimb during the early stance phase. The early stance phase changes in the distal hindlimb suggest rapid changes in the internal forces of the limb and should be of importance to the orthopaedic health of Standardbred trotters. These rapid changes at the fetlock joint and hock joint during the early stance may be important in lameness as excessive rapid and repetitive loading and movement are thought to induce joint damage (Radin et al. 1991).

Animals↗
PubMed1996

Clara cell secretory protein: a determinant of PCB bioaccumulation in mammals.

Clara cell secretory protein (CCSP) is a product of nonciliated cells of the conducting airway epithelium. The normal physiological function of CCSP is unknown. However, the ability of CCSP to bind small lipophilic molecules, such as steroid hormones and certain pollutants, has led to speculation that this protein may mediate the biological accumulation of potentially harmful polychlorinated biphenyl (PCB) metabolites within the lung. To investigate the contribution of CCSP in the in vivo accumulation of methylsulfonyl-PCB, a line of mice was established that were homozygous for a null allele of the CCSP gene. CCSP-deficient mice were healthy and fertile, with no gross physiological or pathological abnormalities Parenteral challenge with the PCB metabolite 4-methylsulfonyl-2,2',4',5,5'-pentachlorobiphenyl (MeSO2-PCB) demonstrated that CCSP-deficient mice no longer accumulate this class of pollutants within lung and kidney tissues. These data demonstrate that CCSP is the determinant for MeSO2-PCB accumulation within mice and support the notion that bioconcentration of MeSO2-PCB pollutants occurs at sites of CCSP localization, such as the respiratory and reproductive tracts of humans.

Animals↗
PubMed1996

Alpha-quartz-induced chemokine expression by rat lung epithelial cells: effects of in vivo and in vitro particle exposure.

Chemokines are chemotactic cytokines that can play a key role in leukocyte recruitment to sites of tissue injury or infection. Previous studies have demonstrated that exposure to alpha-quartz as well as other noxious particles increases chemokine gene expression in rat lung, although the cells responsible for chemokine expression and the mechanisms underlying this response have remained unclear. The present studies demonstrate that exposure of rats to alpha-quartz induced expression of mRNA for the chemokine macrophage-inflammatory protein (MIP)-2 in epithelial cells lining the terminal bronchioles and alveolar ducts as well as macrophages and alveolar type II cells in the more distal lung. Treatment of rats with an anti-MIP-2 antiserum before alpha-quartz exposure markedly attenuated neutrophilic infiltration of the lungs demonstrating an important role for MIP-2 in alpha-quartz-induced pulmonary inflammation. In vitro exposure of primary cultures of rat alveolar type II cells or the rat alveolar type II cell line RLE-6TN to tumor necrosis factor-alpha, endotoxin, or alpha-quartz increased mRNA for MIP-2 as well as the structurally and functionally similar chemokine cytokine-induced neutrophil chemoattractant but not the chemokine MIP-1 alpha. The alpha-quartz-induced increase in epithelial MIP-2 mRNA resulted, at least in part, from increased gene transcription and was associated with the release of active MIP-2 protein. Induction of RLE-6TN MIP-2 and cytokine-induced neutrophil chemoattractant mRNA expression was not unique to alpha-quartz, being also increased by crocidolite asbestus fibers but not by titanium dioxide or MMVF-10 glass fibers. These findings indicate that epithelial cells contribute to chemokine expression in rat lung after exposure to alpha-quartz and potentially other noxious particles and suggest that alpha-quartz-activated MIP-2 expression in vivo results, at least in part, from a direct action of the particles on the lung epithelium.

Animals↗
PubMed1996

A retrospective study of the maintenance requirements associated with implant stabilised mandibular overdentures.

The maintenance requirements of a group of 58 patients, treated with the IMZ osseointegrated implant system and mandibular overdentures were investigated. Prostheses were retained by either bar and clip or separate stud attachments. The patients were followed up regularly for periods of between one and six years. The median number of maintenance procedures required per patient per year varied between 1-5. Detailed examination of the data revealed that a wide range of maintenance procedures was required, including replacement prostheses in 46% of cases. There were some differences related to the retentive elements used for the prostheses.

Adult↗
PubMed1995

Prosthetic management of the atrophic mandible using endosseous implants and overdentures: a six year review.

This paper presents the treatment results and experiences gained from a retrospective study of patients treated with the IMZ osseo-integrated implant system and mandibular overdentures. Patients experiencing problems wearing conventional dentures were assessed by the implant team and 65 cases were treated with 154 endosseous implants placed in the edentulous mandible. Two to four implants were placed in each case and in addition some patients have had augmentation of the mandible with hydroxyapatite. The definitive mandibular prostheses were supported by both implants and the residual ridges. A variety of retention systems were utilised, which included different types of bar and clip, stud attachments, and magnets. The patients have been followed up regularly and evaluated after periods of between one and six years. Six implants have failed over this time resulting in a success rate of over 96%. Most patients expressed a high degree of satisfaction with their new overdentures. There was, however, a considerable burden of maintenance care required for the patient group examined. The findings demonstrate that implant retained overdentures offer a highly effective means of oral rehabilitation for the atrophic mandible, restoring both oral function and facial form.

Adult↗
PubMed1995

Influence of clinician workload and patterns of treatment on survival from breast cancer.

Chemotherapy and hormone therapy prolong disease-free and overall survival for patients with breast cancer in the clinical-trial setting, but it is not clear if this translates into a benefit on a population basis. It is also not clear if surgical caseload has any influence on survival. We used cancer-registry data from 12,861 patients with breast cancer treated in Yorkshire, UK, between 1979 and 1988, and found that patients of surgeons with higher rates of usage of chemotherapy and hormone therapy (regional mean usage 9.3%, range 0-46%) had prolonged survival. There was considerable variation in survival of breast cancer patients between surgeons, but their rate of use of chemotherapy and hormone therapy explained about 26% of this survival variation. Had the practice of the surgeons with the better outcomes been used by all treating clinicians, 5-year survival would have increased by about 4-5%. Examination of differences in survival as a function of consultant caseload demonstrated poorer results amongst those surgeons treating less than 30 new cases of breast cancer per year (risk ratio [95% CI] for treating > 30 compared with < 10 = 0.85 [0.77-0.93]). We recommend that patients with breast cancer be dealt with only by clinicians who see more than 30 new cases per year and who have a full range of treatment options available within a multidisciplinary setting.

Aged↗