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Biomedical subjects

S MacDonald

Publications and source records attributed to S MacDonald.

At least 73 records · Page 4Linked to original sources
PubMed1992

Multiple cardiovascular disease risk factors in Canadian adults. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To estimate the prevalence and distribution of the coexistence of major cardiovascular disease (CVD) risk factors among Canadian adults. DESIGN: Population-based cross-sectional surveys. SETTING: Nine Canadian provinces, from 1986 to 1990. PARTICIPANTS: A probability sample of 26,293 men and women, aged 18 to 74 years, was selected from provincial health insurance registries. For 20,582 of these participants, at least two blood pressure (BP) measurements were taken using a standardized technique. At a subsequent visit to a clinic, two additional BP readings, anthropometric measurements and a blood specimen for plasma lipid analysis were obtained. OUTCOME MEASURES: The percentage distribution of subjects by number of major risk factors (smoking, high BP and elevated blood cholesterol level) and by concomitant factors (body mass index [BMI], ratio of waist to hip circumference [WHR], physical activity, diabetes, awareness of CVD risk factors and education). MAIN RESULTS: Sixty-four percent of men and 63% of women had one or more of the major risk factors. Prevalence increased with age to reach 80% in men and 89% in women aged 65 to 74 years. Prevalence of two or three risk factors was highest among men in the 45-54 age group (34%) and in women in the 65-74 age group (37%). The most common associations were between smoking and high blood cholesterol level (10%) and between high BP and high blood cholesterol level (8%). Prevalence of high BP and elevated blood cholesterol, alone or in combination, increased with BMI and WHR. Smoking, elevated blood cholesterol, BMI and prevalence of one or more risk factors increased with lower level of education. Less than 48% of participants mentioned any single major risk factor as a cause of heart disease. Awareness was lowest in the group with fewest years of education. CONCLUSION: The findings of this study call for an approach to reduce CVD that stresses collaboration of the different health sectors to reach both the population as a whole and the individuals at high risk.

Adult↗
PubMed1992

Compliance with a nonrecapping needle policy.

Compliance with nonrecapping needle policies is poor. Accidental needlestick injuries account for up to 80% of reported occupational needle exposures, and 45% of needlestick injuries occur at recapping. To determine the degree of compliance with in-house nonrecapping and needle disposal policies, the authors undertook an unannounced survey of needles disposed in designated sharps disposal containers and, via a questionnaire, surveyed attitudes to policies. The results show between 46 and 77% of needles were being recapped with 9 to 20% of bloodstained needles recapped before disposal. Recapping devices were rarely used and two-handed recapping techniques predominated. Highest rates of recapping were seen in intensive care, intermediate care and medical care units. Common reasons for recapping include inability to dispose immediately of needles properly, and sharps containers being too far away. Awareness of the risks of recapping was widespread with over 90% of respondents having been instructed in proper needle disposal techniques. While few health care professionals disagreed with non-recapping and needle disposal policies, many--for various reasons--persist in hazardous needle disposal practices.

Health Knowledge, Attitudes, Practice↗
PubMed1991

New pharmacologic approaches to the prevention of space/motion sickness.

Fundamental approaches in selection of new agents for evaluation in prevention of space/motion sickness (SMS) are reviewed. The discussion centers on drugs under investigation at the Johnson Space Center. Methodology that employs the rotating chair for measuring SMS symptomatology and susceptibility is described. The most obvious approach to the development of new agents relies on selection of agents from drug classes that possess pharmacologic properties of established anti-motion sickness agents. A second approach selects drugs that are used to prevent emesis caused by means other than exposure to motion. The third approach relies on basic research that characterizes individual differences in susceptibility. The hypothesis is: detection of individual differences leads to identification of specific drugs, which target physiologic systems that show individual differences. These physiologic systems are targets for therapy and may play a role in the etiology of SMS. Two drugs that reduce susceptibility to SMS include dexamethasone and d(CH2)5Tyr(Me)AVP, a vasopressin (AVP)V1 antagonist. The latter peptide has demonstrated complete blockade of emesis and other significant symptoms in squirrel monkeys. These studies were predicated on observations that subjects who were more resistant to SMS had higher plasma AVP after severe nausea than subjects with lower resistances. Investigations are underway to test a 0.5-mg intravenous dose in humans. Kappa opioid agonists inhibit AVP release and offer new therapeutic possibilities and advantages over AVP peptides. This review details the experimental data collected on AVP and adrenocorticotropin. The literature supports interrelated roles for AVP and opioid peptides in SMS. Experimental testing of kappa agonists is warranted because specific opioid agonists act at neuroanatomical sites causing nausea and vomiting. It is argued opioid receptors in the chemoreceptor trigger zone and vomiting center stimulate and inhibit the emetic response, respectively. The evidence suggests kappa and/or mu receptors at VC are involved in inhibition of emesis, whereas delta opioid receptors at CTZ are involved in stimulation of emesis.

Drug Therapy↗
PubMed1991

Nosocomial legionnaires' disease: lessons from a four-year prospective study.

We studied all cases of nosocomial pneumonia at our 800-bed tertiary care hospital from September 1983 to September 1987. Of the 813 cases of nosocomial pneumonia, 31 (3.8%) were definite (isolation of organism or fourfold rise in titer) and 21 (2.5%) were possible cases (single or stable antibody titer of greater than or equal to 1:256) of legionnaires' disease. The definite cases involved a more severe form of pneumonia and a significantly higher mortality rate--64% versus 14% (p less than 0.0009) compared with the possible cases. Despite attempted comprehensive surveillance, only four (13%) of the definite cases of legionnaires' disease were found that would not have been diagnosed if the study were not ongoing. The yield from adequate (4- to 6-week convalescent serum samples) serologic testing was 5%, whereas the yield from sputum culture was 11%. We conclude that targeted surveillance of immunosuppressed patients with nosocomial pneumonia by culture of respiratory tract secretions for Legionella pneumophila is adequate for monitoring for the presence of legionnaires' disease in a hospital.

Cross Infection↗
PubMed1991

Control of endemic nosocomial legionnaires' disease by using sterile potable water for high risk patients.

In a setting where potable water is contaminated with Legionella pneumophila serogroup 1, we performed two case control studies. The first case control study consisted of 17 cases of nosocomial Legionnaires' disease (LD) and 33 control (the patients who were admitted to the ward where the case was admitted immediately before and after the case) subjects. Cases had a higher mortality rate 65% vs 12% (P less than 0.004); were more likely to have received assisted ventilation (P less than 0.00001); to have nasogastric tubes (P less than 0.0004) and to be receiving corticosteroids or other immunosuppressive therapy (P less than 0.0001). Based on the results of this study, sterile water was used to flush nasogastric tubes and to dilute nasogastric feeds. Only 3 cases of nosocomial LD occurred during the next year compared with 12 the previous year (P less than 0.0001). Nine cases subsequently occurred and formed the basis for the second case-control study. Eighteen control subjects were those patients admitted to the same unit where the case developed LD, immediately before and after the case. The mortality rate for the cases was 89% vs 6% for controls (P less than 0.00003). The only other significant difference was that cases were more likely to be receiving corticosteroids or other immunosuppressive therapy 89% vs 39% (less than 0.01). We hypothesized that microaspiration of contaminated potable water by immunocompromised patients was a risk factor for nosocomial Legionnaires' disease. From 17 March 1989 onwards such patients were given only sterile potable water. Only two cases of nosocomial LD occurred from June 1989 to September 1990 and both occurred on units where the sterile water policy was not in effect. We conclude that aspiration of contaminated potable water is a possible route for acquisition of nosocomial LD in our hospital and that provision of sterile potable water to high risk patients (those who are receiving corticosteroids or other immunosuppressive drugs; organ transplant recipients or hospitalized in an intensive care unit) should be mandatory.

Case-Control Studies↗
PubMed1990

The effect of saccular ablation on vertical optokinetic after-nystagmus in squirrel monkeys.

The effect of bilateral saccular ablation on the asymmetry of vertical optokinetic after-nystagmus (OKAN) was studied in squirrel monkeys. No significant changes occurred in the initial slow-phase eye velocity (SPEV) or the time constant of the upward or downward OKAN first phase (OKAN-I) under various stimulus conditions. However, with a protracted downward stimulus, the maximum SPEV and the number of beats of the slow-phase-up OKAN second phase (OKAN-II) significantly increased. This increase should be the result from enhancement of the downward optokinetic input. In contrast, there was only minimal change in the slow-phase-down OKAN-II. Thus, the asymmetrical dominance of the vertical OKAN (dominance upward) remained the same after saccular deafferentation.

Animals↗
PubMed1990

Autonomic indexes during the vestibular-visual conflict exposure: a squirrel monkey study.

To assess the dynamic changes of the autonomic neural responses evoked by vestibular-visual conflict (VVC) in the squirrel monkey, we analyzed the changes of salivary amount and sodium concentration, and the coefficient of variance (CV) of R-R intervals (RRI) along the time course of VVC exposure given in pitch plane. The sodium concentration and the amount of saliva showed clear increases at the first and second 15 min stimulation periods. The CV of RRI was found to increase over the entire periods of stimulation, and there was a significant difference between the rest value and those in stimulated periods. The correlation between the CV of RRI, and amount of salivation was highly positive. These results indicate the existence of a common pattern of autonomic neural response during VVC, and suggest usefulness of these indexes for objectively monitoring the severity of motion sickness.

Animals↗
PubMed1990

The characteristics of alcoholics in treatment arrested for Driving While Impaired.

Relationships were explored between various characteristics and Driving While Impaired (DWI) arrests, within a sample of 258 hospitalized male alcoholics. Information on four groups of variables were collected using a self-administered questionnaire: socio-demographic characteristics, drinking characteristics, driving characteristics and psychosocial characteristics. Subjects were subdivided into three groups; those with zero DWI arrests, one DWI arrest and multiple DWI arrests. The results of bivariate analyses showed that while Groups 0 and 1 were very similar to each other, those in Group 2 differed significantly from at least one of the other two groups for about one half of the variables studied. A multivariate discriminant analyses demonstrated that there were no important differences between people with 0 and 1 DWI arrests, as people with one arrest were usually classified as having zero arrests.

Accidents, Traffic↗
PubMed1989

Selectivity of mediators released by eosinophils.

The presence of receptors for IgE on eosinophils has drawn the attention on their direct participation in IgE-dependent hypersensitivity reactions. Surface IgE antibodies were detected on eosinophils from allergic patients. The addition of the specific allergen or anti-IgE antibodies to such purified eosinophils induced the release of eosinophil peroxidase, but not of eosinophil cationic protein. These findings associated with results obtained by using electron microscopy and immunogold staining of the various antibodies directed against the granule proteins allowed us to suggest a selectivity in the mediators released by eosinophils. In addition, preliminary results concerning the existence and the functional role of a receptor for IgA on eosinophils are reported, leading to the concept of a particular interaction of eosinophils with immunoglobulins present in the tissues and their participation in local immune responses.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1989

Effect of physical exercise prelabyrinthectomy on locomotor balance compensation in the squirrel monkey.

This study examines the effectiveness of physical exercise, during a prepathology state, on locomotor balance compensation after subsequent unilateral labyrinthectomy in squirrel monkeys. An experimental group underwent 3 hr. of daily running exercise on a treadmill for 3 mo. prior to the surgery, whereas a control group was not exercised. Postoperatively, the locomotor balance function of both groups was tested for 3 mo. There was no significant difference in gait deviation counts in the acute phase of compensation. However, in the chronic compensation maintenance phase, the number of gait deviation counts was fewer in the exercise group, which showed significantly better performance stability.

Animals↗
PubMed1986

Atopy, non-allergic bronchial reactivity, and past history as determinants of work related symptoms in seasonal grain handlers.

One hundred and five young subjects with little or no previous exposure to grain dust were studied before and after a seven week period of grain handling work to determine if there was an association between symptoms experienced at work and pre-employment respiratory symptoms, allergy skin test responses, and non-allergic bronchial reactivity. The incidence of work related symptoms was cough 18%, wheeze 13%, and dyspnoea 14%. The results showed that pre-employment history of respiratory symptoms, positive allergy skin test responses, and a high level of non-allergic bronchial reactivity were significantly associated with these symptoms. These measurements may be useful to predict symptoms associated with exposure to grain dust in new employees and the results suggest that these work related symptoms may be due to allergen induced asthma.

Adolescent↗
PubMed1984

Studies of mitomycin C absorption after intravesical treatment of superficial bladder tumors.

Mitomycin C is an active drug in the treatment of superficial bladder cancer. Although clinical safety of intravesical mitomycin C has been well accepted there are no data on absorption of this drug from the bladder in patients with damaged bladder mucosa. We studied 18 patients for evidence of absorption of mitomycin C after transurethral resection and/or radiation therapy. Mitomycin C is absorbed on intravesical instillation and the degree of absorption depends on the degree of damage to the bladder. Despite some evidence of absorption no systemic effect on bone marrow was observed and no evidence of deoxyribonucleic acid damage was found in any of these patients. Mitomycin C appears to be a safe drug but further studies are indicated to document its safety when used for maintenance therapy.

Antibiotics, Antineoplastic↗
PubMed1984

Immunoenzymatic labeling of monoclonal antibodies using immune complexes of alkaline phosphatase and monoclonal anti-alkaline phosphatase (APAAP complexes).

A murine monoclonal antibody specific for calf intestinal alkaline phosphatase has been prepared and used in an unlabeled antibody bridge technique for labeling monoclonal antibodies. This procedure--the alkaline phosphatase monoclonal anti-alkaline phosphatase (APAAP) method--gives excellent immunocytochemical labeling of tissue sections and cell smears, comparable in clarity and intensity to that achieved with immunoperoxidase labeling. If the enzyme label is developed with a naphthol salt as a coupling agent and Fast Red or hexazotized new fuchsin as a capture agent, a vivid red reaction product is obtained which is very easily detected by the human eye. For this reason the APAAP technique was found particularly suitable for labeling cell smears (for both cytoplasmic and surface-membrane antigens) and for detecting low numbers of antigen-bearing cells in a specimen (e.g., carcinoma cells in a malignant effusion). It was found possible to enhance the intensity of the APAAP labeling reaction substantially by repeating the second and third incubation steps (i.e., the unlabelled "bridge" antibody and APAAP complexes). The APAAP technique was superior to immunoperoxidase labeling for staining tissues rich in endogenous peroxidase, and could be used in conjunction with immunoperoxidase methods for double immunoenzymatic staining. The method was also applicable to the detection of antigenic molecules following their electrophoretic transfer from SDS-polyacrylamide gels to nitrocellulose sheets ("immunoblotting").

Alkaline Phosphatase↗
PubMed1984

Monoclonal antibodies specific for human monocytes, granulocytes and endothelium.

Four monoclonal antibodies against antigens of human myeloid cells have been produced and thoroughly characterized in terms of their reactions with peripheral blood cells, cell lines, nine lymphoid and non-lymphoid tissues and the polypeptides with which they react. UCHM1 and SmO identify antigens present on the majority of blood monocytes and a variable, but lower, proportion of tissue macrophages. From their morphology and location in tissues, these cells appear to be recirculating monocytes. SMO antigen is also present on platelets. In addition, both antibodies stained endothelial cells, SMO in all tissues examined and UCHM1 variably. Biochemical investigation indicated that the UCHM1 antigen is a protein of 52,000 MW while the SMO antigen could not be indentified. The antibodies TG1 and 28 identify antigens mainly present on granulocytes. While mAb 28 reacted with neutrophils, TG1 also stained eosinophils and stained strongly a proportion of monocytes. TG1 also reacted variably with some non-haemopoietic cell lines. Both antibodies reacted predominantly with granulocytes in tissue sections. MAb TG1 precipitated a single polypeptide of 156,000 MW from monocytes and granulocytes, while mAb 28 precipitated non-convalently associated polypeptides of 83,000 and 155,000 MW from granulocytes but only a single molecule from monocytes, corresponding to the lower MW chain of 83,000. The epitope with which mAb 28 reacts appears not to be exposed on the surface of intact monocytes. This suggests that a similar or identical 83,000 MW molecule is made by both neutrophils and monocytes, but that its expression differs according to cell type.

Antibodies, Monoclonal↗
PubMed1983

Intrapericardial teratoma: a continuing challenge.

Intrapericardial teratoma is a rare entity that presents a diagnostic and therapeutic challenge. The authors describe the case of an 18-month-old boy with this condition who was successfully managed by resection of the mass. Computerized axial tomography, radionuclide scanning and angiography are important aids in the preoperative assessment of intrapericardial masses. However, all are nonspecific. Definitive diagnosis can only be established by thoracotomy, resection and microscopic examination of the specimen. The long-term prognosis is good.

Angiography↗
PubMed1982

An analysis of the lymphocytotoxic activity found in sera from patients with hypogammaglobulinaemia.

Sera from 59 patients with hypogammaglobulinaemia (hypogamma) were assessed for lymphocytotoxic activity. The activity was compared with that found in sera from patients with systemic lupus erythematosus (SLE) in titre, class of antibody, target cell, and complement requirements. Sera from patients with hypogamma showed cytotoxic activity when compared with sera from normal donors; however, the activity was far less than that in sera from SLE patients, The cytotoxic titre of both hypogamma and SLE sera was greater against T cells than non-T cells. Sera showing activity could be used to sensitize lymphocytes and render them susceptible to subsequent lysis, but IgM was not detectable on the surface of the sensitized cells. Following sucrose density gradient fractionation of the sera the lymphocytotoxic activity was recovered in those fractions that contained IgM. Lymphocytotoxic activity was dependent on classical complement pathway activity. In all the experiments the hypogamma sera showed the same pattern of activity as the SLE sera, but the activity was always far weaker than that found in SLE sera. The evidence does not suggest that lymphocytotoxicity is likely to be more important in the pathogenesis of hypogamma.

Agammaglobulinemia↗
PubMed1980

Placental infection with Mycoplasma homonis and Ureaplasma urealyticum: clinical correlation.

Placentas from a clinical study group of 446 high-risk pregnancies and 108 normal pregnancies were cultured for Mycoplasma hominis and Ureaplasma urealyticum and examined histologically. Results were compared and correlated with the clinical history. The recovery rate of U urealyticum, but not of M hominis, was significantly higher in the clinical study than in the control group. Isolation of both mycoplasmas was associated with polymorphonuclear leukocyte infiltration of placental membranes, fetal surface, and umbilical cord. Recovery of mycoplasma was significantly higher with prolonged membrane rupture, spontaneous abortion, stillbirth, and early neonatal death. Isolation of U urealyticum, but not of M hominis, was associated with prematurity, lower birth weight, and intrauterine growth retardation.

Abortion, Spontaneous↗