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Biomedical subjects

R Burnett

Publications and source records attributed to R Burnett.

At least 37 records · Page 2Linked to original sources
PubMed1994

DLA-identical bone marrow grafts after low-dose total body irradiation: the effect of canine recombinant hematopoietic growth factors.

Previous studies found that bone marrow (BM) allografts from DLA-identical littermates resulted in survival of two thirds of recipient dogs after otherwise lethal doses of 450 to 600 cGy of total body irradiation (TBI) because of successful allografts or autologous recovery after rejection of the allografts. The current study asked whether survival could be further improved by treating allograft recipients with recombinant canine granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), or G-CSF/SCF. Of 21 dogs, 14 (67%) receiving allografts but no growth factors survived, 10 with successful allografts (including 5 mixed chimeras) and 4 with autologous recovery; whereas 7 animals died, 5 from infections during BM aplasia and 2 from acute graft-versus-host disease. By comparison, 30 of 34 dogs (88%) receiving hematopoietic growth factors in addition to the BM graft survived, 17 with successful allografts (including 10 mixed chimeras) and 13 with autologous recovery; whereas 4 died, all with infection related to BM aplasia after rejection of the allograft. Survival was similar for recipients of G-CSF, SCF, or the combination of G-CSF and SCF. Logistic regression analyses, which accounted for possible effects of TBI dose, showed a trend for improved survival in dogs receiving growth factors (P = .09), no change in allogeneic engraftment (P = .74), and a slight increase in autologous recovery (P = .22). In agreement with previous data, we found that grafts of BM from DLA-identical littermates improved survival of recipient dogs exposed to low but otherwise lethal doses of TBI. A further improvement in survival could be achieved by additional treatment with G-CSF, SCF, or G-CSF/SCF. Results suggest that treatment by hematopoietic growth factors along with BM grafts should be considered for victims of radiation accidents.

Animals↗
PubMed1994

Use of (CA)n polymorphisms to determine the origin of blood cells after allogeneic canine marrow grafting.

We have used a polymerase chain reaction-based assay measuring polymorphic (CA)n repeats, a class of simple sequence repeats, to assess the success of allogeneic canine marrow transplants. Results were compared with those obtained with karyotype analysis of dividing cells in recipients that were sex mismatched with their marrow donors. Twenty recipients were conditioned for transplantation of genotypically DLA-identical littermate marrow by 450 cGy of total-body irradiation. In 2 recipients, results could not be compared, since either only cytogenetic or dinucleotide (CA)n marker data existed. Both dogs had autologous marrow recovery. In 15 of the remaining 18 recipients, complete agreement was found between the results obtained with dinucleotide (CA)n markers, cytogenetic studies, and granulocyte changes after transplantation. Seven of the 15 showed eventual autologous recovery, 6 displayed mixtures of host and donor cells, and 2 showed donor-type hematopoiesis. Two of the 18 dogs showed mixed chimerism with (CA)n markers and autologous recovery by cytogenetics, findings that may be related to differences in cells analyzed by the two techniques--i.e., all nucleated cells by (CA)n markers versus dividing cells by cytogenetics. In one additional recipient, results of marrow cytogenetics, granulocyte changes, and (CA)n markers were consistent with a successful allograft, while peripheral blood cytogenetics suggested autologous recovery, possibly the result of erroneous blood sampling. Polymerase chain reaction-based testing for dinucleotide repeat (CA)n polymorphisms, originally developed for genetic mapping in the dog, is useful and reliable when compared with cytogenetic studies, in assessing the success of allogeneic marrow transplants in dogs.

Animals↗
PubMed1994

Pharmacokinetics of inhaled pyrene in rats.

Male Wistar rats were exposed to micronized aerosol concentrations of a 14C-labeled model polycyclic aromatic hydrocarbon (pyrene) at 200, 500, and 800 mg/m3 for a period of 95 min. Both the 14C label and free pyrene were monitored in the blood, urine, and feces. At the termination of the blood sampling, three of the six rats per dose group were killed and the distribution of [14C]pyrene to eight major tissues was analyzed. The analysis of blood concentration data using a one-compartment pharmacokinetic model revealed that the uptake and elimination kinetic parameters were dose dependent, for both total radioactivity (pyrene plus metabolites) and for pyrene per se, over the range of exposures used in this study. The ratio of the percent excreted via the urinary and fecal routes, collected over a 5-d period postexposure was about 1.0 at each exposure level.

Absorption↗
PubMed1994

Prevalence of childhood asthma across Canada.

BACKGROUND: A large cross-sectional study provided an opportunity to estimate the prevalence of childhood asthma in several regions across Canada. METHODS: In 1988, approximately 18,000 questionnaires were distributed to the families of 5-8 year old children in 30 communities from the following six regions across Canada: the interior of British Columbia, southeastern Saskatchewan, southwestern Ontario, the central region of Ontario, southern Quebec, and the Maritimes (Nova Scotia and Prince Edward Island). These communities were free of point-source air pollutants and selected to represent a range of ambient sulphate concentrations. In all 14,948 questionnaires were returned representing an 83% response rate. RESULTS: Currently present, physician-diagnosed asthma was reported for 4.7% of children by their parents. Persistent wheezing was reported for 13% and persistent cough for 5.9%. Asthma was most common in the two Maritime provinces (7.4%), and least common in British Columbia (3.3%) and Quebec (3.4%). Similar regional differences were seen for persistent cough, persistent wheeze, and also hospital separation rates for asthma which were approximately 800 per 100,000 for the Maritimes and 396 per 100,000 for British Columbia. Differences persisted despite adjustments for several host and environmental (indoor and outdoor) characteristics. CONCLUSIONS: The east coast of Canada may be an endemic area of asthma in Canada. If confirmed by objective measures of asthma, a detailed aetiologic investigation could enhance understanding of this phenomenon and the major environmental determinants of asthma morbidity in general.

Age Factors↗
PubMed1994

Echocardiography of transatrial embolism during cemented and uncemented hemiarthroplasty of the hip.

We performed transoesophageal echocardiography on 20 patients with femoral neck fractures randomly treated with an uncemented Austin-Moore or cemented Hastings hemiarthroplasty. Cemented arthroplasty caused greater and more prolonged embolic cascades than did uncemented arthroplasty. Some emboli were more than 3 cm in length. In some patients the cascades were associated with pulmonary hypertension, diminished oxygen tension and saturation, and the presence of fat and marrow in aspirates from the right atrium.

Arthroplasty↗
PubMed1993

Relevance of history of injury to the diagnosis of meniscal tears.

A consecutive series of 217 arthroscopic meniscectomies has been reviewed in order to investigate the incidence of significant meniscal lesions without obvious precipitating injury. There were 10 bucket handle tears out of 117 (9%) with a mean age of 32 years with no significant injury; 18 flap tears out of 69 (26%) with a mean age of 40 years; and 7 out of 19 (37%) radial tears with a mean age of 36 years also had no significant injury. This study indicates that the absence of a history of injury in the young patient with a symptomatic knee does not exclude significant meniscal tears, such as a bucket handle, and therefore has implications for history taking and diagnosis.

Adolescent↗
PubMed1992

Modification of tumor promotion in the mouse skin by exposure to an alternating magnetic field.

Some epidemiological studies have suggested that exposure to an alternating magnetic field may increase the incidence of some cancers. Our earlier study of carcinogenesis in mouse skin, indicated that exposure to a magnetic field (MF) alone did not promote the growth of tumors. In the present experiment, the ability of a MF to act as a tumor copromoter was investigated. The dorsal skins of female SENCAR mice (6-7-weeks-old) were treated with 10 nmol of 7,12-dimethylbenzanthracene (DMBA) to initiate the carcinogenic process and then tumor development was promoted, for 23 weeks, by weekly applications of 4.9 nmol (0.3 microgram) of 12-0-tetradecanoylphorbal-13-acetate (TPA). One group of 48 mice were exposed to a 60-Hz magnetic field of 2 mT (20 Gauss) for 6 h/day 5 days/week, while a similar group (48 mice) were sham exposed. After week 12, the percentage of mice with tumors and the mean number of tumors per mouse, were higher for the group exposed to MF. At week 18, for example, where the differences between field and sham groups were statistically significant, the percentage of mice with tumors were, respectively, 25% and 8% (P less than 0.05, Fisher exact) and, the mean yield of tumors 1.9 +/- 0.69 and 0.65 +/- 0.46 (mean +/- S.E.M.) (P less than 0.05, Wilcoxon). At week 23 these differences were no longer statistically significant.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Behavioral and cognitive-behavioral approaches to chronic pain: recent advances and future directions.

Behavioral and cognitive-behavioral approaches to chronic pain are receiving increasing attention from researchers and clinicians. This article reviews and highlights recent research advances and future research directions. Assessment research reviewed includes studies examining the social context of pain, the relationship of chronic pain to depression, cognitive variables affecting pain, and comprehensive assessment measures. Treatment outcome studies reviewed are those evaluating the effects of behavioral and cognitive-behavioral treatments for chronic pain. These studies focus on comparisons of behavioral treatment with control conditions, comparisons of two behavioral treatments, and prevention of chronic pain. Future directions for assessment and treatment research are outlined.

Chronic Disease↗
PubMed1991

Respiratory health effects of home dampness and molds among Canadian children.

In 1988, the authors conducted a questionnaire-based study on the health effects of the indoor environment in 30 Canadian communities. This paper focuses on the association between the respiratory health of young children and home dampness and molds. A total of 17,962 parents or guardians of schoolchildren received a questionnaire, and 14,948 (83.2%) questionnaires were returned. Children living in mobile homes, tents, and boats were excluded as were those with cystic fibrosis, leaving 13,495 children included in the study group. The housing stock was distributed as follows: 81% were one-family detached homes, 6% were one-family attached homes, and 13% were buildings for two or more families. Molds were reported in 32.4%, flooding in 24.1%, and moisture in 14.1% of the homes. Prevalences of all respiratory symptoms were consistently higher in homes with reported molds or dampness; i.e., adjusted odds ratios ranged from 1.32 (95% confidence interval 1.06-1.39) for bronchitis to 1.89 (95% confidence interval 1.58-2.26) for cough. The prevalence of home dampness or molds, 37.8%, indicates that it is an important public health issue. Further studies are required to elucidate the pathogenesis.

Canada↗
PubMed1991

Technical aspects of the use of the Russell-Taylor reconstruction nail.

The introduction of the reconstruction nail has broadened the indications for the intramedullary fixation of difficult femoral fractures. The operative technique is, however, complicated. Some technical difficulties encountered during its use are presented, together with guidance to allow these problems to be avoided.

Adult↗
PubMed1991

Adverse health effects among adults exposed to home dampness and molds.

To investigate the association between home dampness and mold and health, questionnaires were administered through the primary school system to parents of school-aged children in six regions of Canada. The present report focuses on the symptoms of the 14,799 adults at least 21 yr of age. The overall response rate was 83%, and missing values for individual variables ranged from 3 to 8%. The presence of home dampness and/or molds (that is, damp spots, visible mold or mildew, water damage, and flooding) was reported by 38% of respondents. The prevalence of lower respiratory symptoms (any cough, phlegm, wheeze, or wheeze with dyspnea) was increased among those reporting dampness or mold compared with those not reporting dampness or mold as follows: 38 versus 27% among current smokers, 21 versus 14% among exsmokers, and 19 versus 11% among nonsmokers (all p values less than 0.001). This association persisted after adjusting for several sociodemographic variables (including age, sex, and region) and several other exposure variables (including active and passive cigarette smoke, natural gas heating, and wood stoves). The odds ratio between symptoms and dampness was 1.62 (95% confidence interval, 1.48 to 1.78) in the final model chosen. This association persisted despite stratification by the presence of allergies or asthma. Exposure to home dampness and mold may be a risk factor for respiratory disease in the Canadian population.

Adult↗
PubMed1991

Souter-Strathclyde arthroplasty of the rheumatoid elbow. 23 cases followed for 3 years.

Twenty-three elbows in 17 rheumatoid arthritis patients have undergone unconstrained Souter-Strathclyde elbow replacements since March 1984. One patient developed a deep-wound infection, and 4 others had a temporary ulnar nerve paresis. At follow-up 3 (0.5-6) years postoperatively, there was a moderate improvement in the arc of movements: 25 degrees in extension-flexion and 45 degrees in forearm rotation. Pain relief was achieved in 20 cases. Three elbows required revision, two following recurrent dislocation and the other after a humeral fracture and component loosening.

Adult↗
PubMed1989

Respiratory health effects associated with ambient sulfates and ozone in two rural Canadian communities.

A cross-sectional epidemiological study investigating the respiratory health of children in two Canadian communities was conducted in 1983-1984 in Tillsonburg, Ontario, located in a region of moderately elevated concentrations of transported air pollutants, and in Portage la Prairie, Manitoba, situated in a low pollution area. There were no significant local sources of industrial emissions in either community. Seven hundred and thirty-five children aged 7-12 were studied in the first town and 895 in the second. Respiratory health was assessed by the measurement of the forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) of each child, and by evaluation of the child's respiratory symptoms and illnesses using a parent-completed questionnaire. Sulfur dioxide (SO2), sulfate, and particulate nitrate levels were significantly higher in Tillsonburg than in Portage la Prairie (P less than 0.05), but nitrogen dioxide (NO2) and inhalable particles (PM10) differed little between the communities. Historical data in the vicinity of Tillsonburg indicated that average annual levels of sulfates, total nitrates, and ozone (O3) did not vary markedly in the 9-year period preceding the study. The results show that Tillsonburg children had statistically significant (P less than 0.001) lower levels of 2% for FVC and 1.7% for FEV1.0 as compared with children in Portage la Prairie. These differences could not be explained by parental smoking or education, the use of gas cooking or wood heating fuels, pollution levels on the day of testing, or differences in age, sex, height, or weight. The differences persisted when children with cough with phlegm, asthma, wheeze, inhalant allergies, or hospitalization before age 2 for a chest illness were excluded from analysis. With the exception of inhalant allergies, which occurred more frequently in Tillsonburg children, the prevalence of chronic respiratory symptoms and illnesses was similar in the two communities.

Air Pollutants↗