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Biomedical subjects

Donald W McKay

Publications and source records attributed to Donald W McKay.

15 recordsLinked to original sources
PubMed2006

Prolactin responses to infant cues in men and women: effects of parental experience and recent infant contact.

We used a longitudinal design to test whether parental experience differentially affects the development of prolactin responses to infant cues in men and women. Couples provided two blood samples at three tests, one test just before their babies were born, and two tests during the early postnatal period (n=21). Nine couples repeated the tests near the birth of their second babies. In the 30 min between the two samples, couples listened to recorded infant cries at the prenatal test and held their baby (fathers) or a doll (mothers) at the postnatal tests. Blood samples were analyzed for prolactin concentrations. Prolactin values were then related to sex and parity differences as well as to questionnaire data concerning emotional responses to infant cries and previous infant contact. We found that (1) prior to the birth of both the first and second babies, women's prolactin concentrations increased after exposure to infant stimuli, whereas men's prolactin concentrations decreased; postnatal sex differences varied with parity; (2) women's prolactin reactivity did not change significantly with parental experience; (3) the same men's prolactin concentrations decreased after holding their first newborns but increased after holding their second newborns; this change was not gradual or permanent; (4) men reporting concern after hearing recorded infant cries showed a different postnatal pattern of prolactin change after holding their babies than men not reporting concern; and (5) men who had little contact with their babies just prior to testing had a more positive prolactin response than men who had recently held their babies for longer periods. Although parental experience appears to affect men's prolactin responses, differences in reactivity were also related to patterns of recent infant contact and individual differences in responses to infant cues.

Adult↗
PubMed2006

The 2006 Canadian Hypertension Education Program recommendations for the management of hypertension: Part I--Blood pressure measurement, diagnosis and assessment of risk.

OBJECTIVE: To provide updated, evidence-based recommendations for the diagnosis and assessment of adults with high blood pressure. OPTIONS AND OUTCOMES: For persons in whom a high blood pressure value is recorded, a diagnosis of hypertension is dependent on the appropriate measurement of blood pressure, the level of the blood pressure elevation, the approach used to monitor blood pressure (office, ambulatory or home/self), and the duration of follow-up. In addition, the presence of cardiovascular risk factors and target organ damage should be assessed to determine the urgency, intensity and type of treatment. For persons diagnosed as having hypertension, estimating the overall risk of adverse cardiovascular outcomes requires an assessment for other vascular risk factors and hypertensive target organ damage. EVIDENCE: MEDLINE searches were conducted from November 2004 to October 2005 to update the 2005 recommendations. Reference lists were scanned, experts were polled, and the personal files of the authors and subgroup members were used to identify other studies. Identified articles were reviewed and appraised using prespecified levels of evidence by content and methodological experts. As per previous years, the authors only included studies that had been published in the peer-reviewed literature and did not include evidence from abstracts, conference presentations or unpublished personal communications. RECOMMENDATIONS: The present document contains recommendations for blood pressure measurement, diagnosis of hypertension, and assessment of cardiovascular risk for adults with high blood pressure. These include the accurate measurement of blood pressure, criteria for the diagnosis of hypertension and recommendations for follow-up, assessment of overall cardiovascular risk, routine and optional laboratory testing, assessment for renovascular and endocrine causes, home and ambulatory blood pressure monitoring, and the role of echocardiography for those with hypertension. Key features of the 2006 recommendations include continued emphasis on an expedited diagnosis of hypertension, an in-depth review of the role of global risk assessment in hypertension therapy, and the use of home/self blood pressure monitoring for patients with masked hypertension (subjects with hypertension who have a blood pressure that is normal in clinic but elevated on home/self measurement). VALIDATION: All recommendations were graded according to the strength of the evidence and were voted on by the 45 members of the Canadian Hypertension Education Program Evidence-Based Recommendations Task Force. All recommendations reported herein received at least 95% consensus. These guidelines will continue to be updated annually.

Advisory Committees↗
PubMed2006

Social and hormonal bases of individual differences in the parental behaviour of birds and mammals.

We present an overview of research on how social experiences and hormonal responses affect individual variation in parental care of birds and mammals. The parental roles of prolactin and glucorticoids (corticosterone or cortisol) have many similarities in birds and in mammals. Prolactin may be involved in the initiation of parental interactions, with prolactin variation possibly explaining individual differences in parental decision-making. Glucocorticoid levels increase when parents have to work harder, with some individuals showing greater hormonal and behavioural responses than others. Testosterone interferes with paternal behaviour in birds, but its role is more complex and species-specific in male mammals. We examine these differences in an adaptive framework, where retaining flexibility of response has allowed individuals to respond differentially to social opportunities and environmental change.

Animals↗
PubMed2006

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect.

OBJECTIVES: BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse. METHODS: Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices. RESULTS: Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol. CONCLUSIONS: Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.

Aged↗
PubMed2005

Protein synthesis and the mechanisms of lasting change in anxiety induced by severe stress.

Brief, unprotected exposure of rats to cats (predator stress) may be lastingly anxiogenic in a variety of tests of rodent anxiety. Recent findings suggest that predator stress induced plasticity in neural circuitry implicated in fear learning underlies some of these anxiogenic effects. In addition, recent work implicates a consolidation-like process in the impact of predator stress on anxiety in that effects of predator stress may be interrupted by immediate post stressor pharmacological interventions. The present study tested whether "consolidation" of the anxiogenic effects of predator stress were dependent on protein synthesis. In addition, the study examined whether a protein synthesis dependent reconsolidation-like process was at work when rats were exposed to a cat twice. Anisomycin (210 mg/kg) or vehicle (Tween 80 in saline) was injected subcutaneously 1 min after a single cat exposure (consolidation test paradigm) or a 1 min after a second cat exposure (reconsolidation test paradigm) and behavior tested 7-8 days after predator stress. In the consolidation test paradigm, anisomycin blocked the anxiogenic effects of predator stress in the elevated plus maze (EPM) measured with open arm exploration. Moreover, anisomycin blocked the potentiation of startle by predator stress when rats were startled in the light, but not when startled in the dark. In contrast, the delay of habituation of startle produced by predator stress was unaffected by anisomycin. Suppression of risk assessment in the EPM by predator stress was not affected by anisomycin either. In startle testing, vehicle injection 1 min after predator stress led to a lasting suppression, rather than enhancement of startle response. Vehicle plus predator stress enhanced and prolonged corticosterone level changes sampled over 30-180 min after treatment when compared to handled or predator stressed only rats. In addition, predator stress plus vehicle suppression of startle was blocked by a benzodiazepine anxiolytic (chloradiazepoxide) or the glucorticoid receptor (GR) blocker RU486. Both drugs returned startle to the predator stressed only heightened levels. It is argued that an added anxiogenic effect of vehicle injection plus predator stress leads to a suppression, rather than enhancement of startle. Startle suppression appears to be mediated, in part, by activation of GR by corticosterone which engages a protein synthesis dependent process, since anisomycin blocked the startle suppressive effects of vehicle. Startle suppression also appeared to be independent of the startle enhancing effect of predator stress and in competition with it. Since predator stress may model aspects of hyperarousal associated with post traumatic stress disorder (PTSD), implications of these findings for understanding of mechanisms of initiation of the disorder and for treatment are discussed.

Analysis of Variance↗
PubMed2005

New algorithm for the diagnosis of hypertension.

Most national and international guidelines for diagnosing hypertension include 24-h ambulatory blood pressure monitoring (ABPM) and self (home) BP monitoring (SBPM) as optional methods for identifying hypertensive patients. However, none of the current guidelines have yet included ABPM or SBPM as fundamental tools for diagnosing hypertension, preferring instead to rely on conventional office readings recorded by mercury sphygmomanometry. During the past 10 years, clinical outcome studies have consistently reported 24-h ABPM and SBPM to be significantly better predictors of cardiovascular events compared with the office BP, even when recorded under "research conditions." Based on the available evidence, the Canadian Hypertension Education Program has now developed an algorithm for diagnosing hypertension that offers three options: 1) conventional office BP, 2) SBPM, or 3) 24-h ABPM. Out-of-office BP measurements are recommended, whenever feasible, to minimize both measurement error associated with mercury sphygmomanometry and the white coat effect experienced by some patients.

Algorithms↗
PubMed2005

Misclassification of blood pressure by usual measurement in ambulatory physician practices.

BACKGROUND: Standardized measurement of blood pressure (BP) is widely recommended but rarely followed in usual clinical practice. METHODS: We compared the classification of hypertension status of 107 patients referred by family physicians for ambulatory BP monitoring (ABPM) and with elevated clinic BP when assessed by usual clinical office measurement, a trained hypertension research nurse using a standardized measurement protocol, or an ambulatory BP monitor. RESULTS: Usual clinic readings resulted in higher BP readings than those obtained by the research nurse: mean (95% confidence interval [CI]), 10.8 (8.0 to 13.6)/4.9 (2.9 to 6.9) mm Hg, the daytime ambulatory BP 7.7 (5.1 to 10.3)/5.1 (3.0 to 7.1), and the 24-h ambulatory BP 12.1 (9.6 to 14.6)/8.9 (6.9 to 10.9). The interpretation of whether the patient had a hypertensive versus normotensive reading in the usual clinic setting differed in 42% of patients relative to standardized nurse readings. CONCLUSIONS: Following standardized technique is important for correct classification of the BP status of patients. Use of usual or casual technique results in higher readings than standardized or ambulatory BP readings. This study indicates that significant improvement in the assessment of BP is required for diagnosis and optimal management of hypertension. Consideration strongly needs to be given to the development of alternative methods of assessing BP in clinical practice.

Ambulatory Care Facilities↗
PubMed2005

The 2005 Canadian Hypertension Education Program recommendations for the management of hypertension: part 1- blood pressure measurement, diagnosis and assessment of risk.

OBJECTIVE: To provide updated, evidence-based recommendations for the diagnosis and assessment of adults with high blood pressure (BP). OPTIONS AND OUTCOMES: For persons in whom a high BP value is recorded, the assignment of a diagnosis of hypertension is dependent on the appropriate measurement of BP, the level of the BP elevation and the duration of follow-up. In addition, the presence of cardiovascular risk factors and target organ damage should be assessed to determine the urgency, intensity and type of treatment. For persons diagnosed as having hypertension, estimating overall risk of adverse cardiovascular outcomes requires an assessment of other vascular risk factors and hypertensive target organ damage. EVIDENCE: MEDLINE searches were conducted from November 2003 to October 2004 to update the 2004 recommendations. Reference lists were scanned, experts were polled, and the personal files of the authors and subgroup members were used to identify other studies. Identified articles were reviewed and appraised using prespecified levels of evidence by content and methodological experts. As per previous years, only studies that had been published in the peer-reviewed literature were included; evidence from abstracts, conference presentations and unpublished personal communications was not included. RECOMMENDATIONS: This document contains recommendations for BP measurement, diagnosis of hypertension and assessment of cardiovascular risk for adults with high BP. These include the accurate measurement of BP, criteria for diagnosis of hypertension, and recommendations for follow-up, assessment of overall cardiovascular risk, routine and optional laboratory testing, assessment for renovascular and endocrine causes, home and ambulatory BP monitoring, and the role of echocardiography for those with hypertension. Key features of the 2005 recommendations include an expedited diagnostic algorithm for hypertension and an endorsement of the use of home/self and ambulatory BP assessment as validated techniques in establishing the diagnosis of hypertension. VALIDATION: All recommendations were graded according to the strength of the evidence and voted on by the 43 members of the Canadian Hypertension Education Program Evidence-Based Recommendations Task Force. All recommendations reported in the present paper received at least 95% consensus. These guidelines will continue to be updated annually.

Blood Pressure Monitoring, Ambulatory↗
PubMed2004

The 2004 Canadian Hypertension Education Program recommendations for the management of hypertension: Part I--Blood pressure measurement, diagnosis and assessment of risk.

OBJECTIVE: To provide updated, evidence-based recommendations for the assessment of the diagnosis, cardiovascular risk and identifiable causes for adults with high blood pressure. OPTIONS: For persons in whom a high blood pressure value is recorded, the assignment of a diagnosis of hypertension is dependent on the appropriate measurement of blood pressure, the level of the blood pressure elevation and the duration of follow-up. In addition, the presence of concomitant vascular risk factors, target organ damage and established atherosclerotic diseases should be assessed to determine the urgency, intensity and type of treatment. For persons diagnosed as having hypertension, defining overall risk of adverse cardiovascular outcomes requires an assessment of concomitant vascular risk factors, including laboratory testing, a search for target organ damage and an assessment for modifiable causes of hypertension. Home and ambulatory blood pressure assessment and echocardiography are options for selected patients. OUTCOMES: The identification of persons at increased risk of adverse cardiovascular outcomes; the quantification of overall cardiovascular risk; and the identification of persons with potentially modifiable causes of hypertension. EVIDENCE: Medline searches were conducted from November 2001, one year before the period of the last revision of the Canadian recommendations for the management of hypertension, to October 2003. Reference lists were scanned, experts were polled, and the personal files of subgroup members and authors were used to identify other studies. Identified articles were reviewed and appraised using prespecified levels of evidence by content experts and methodological experts. VALUES: A high value was placed on the identification of persons at increased risk of cardiovascular morbidity and mortality, and persons with identifiable and potentially modifiable causes of hypertension. BENEFITS, HARMS AND COSTS: The identification of persons at higher risk of cardiovascular disease will permit counselling for lifestyle maneuvers and introduction of antihypertensive drugs to reduce blood pressure for patients with sustained hypertension. The identification of specific causes of hypertension may permit the use of cause-specific interventions. For certain subgroups of patients and specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality. RECOMMENDATIONS: The document contains recommendations for blood pressure measurement, diagnosis of hypertension and assessment of cardiovascular risk for adults with high blood pressure. These include the accurate measurement of blood pressure, criteria for diagnosis of hypertension, and recommendations for follow-up, assessment of overall cardiovascular risk, routine and optional laboratory testing, assessment for renovascular and endocrine causes, home and ambulatory blood pressure monitoring, and the role of echocardiography for those with hypertension. VALIDATION: All recommendations were graded according to strength of evidence and voted on by the Canadian Hypertension Education Program Evidence-Based Recommendations Task Force. Only the recommendations that achieved high levels of consensus are reported. These guidelines will be updated annually.

Adult↗
PubMed2004

Eprosartan mesylate effectively reduces systolic and diastolic blood pressure in a Canadian primary care setting.

BACKGROUND: Evidence suggests that antihypertensive agents may have differential effects on systolic blood pressure (SBP) and that home BP monitoring (HBPM) may enhance the antihypertensive effects. OBJECTIVES: To evaluate the efficacy and safety of eprosartan mesylate in the treatment of hypertension, particularly on SBP in older subjects, and to assess the role of HBPM. METHODS: A randomized, open-label, 10-week study was conducted in 35 primary care centres across Canada. One hundred ninety-eight subjects (aged 60 to 84 years) with mild to moderate hypertension (SBP 140 mmHg to 179 mmHg, diastolic BP [DBP] 109 mmHg or less) were included in the analysis. All subjects received open-label eprosartan mesylate 600 mg once daily, and were randomly assigned to eprosartan treatment alone or eprosartan plus HBPM. Hydrochlorothiazide 12.5 mg once daily could be added after week 4. The primary outcomes were the change in SBP at study end and the effect of HBPM on SBP. RESULTS: In the eprosartan and eprosartan plus HBPM groups, SBP was reduced by 17.6 mmHg and 19.9 mmHg, and DBP was reduced by 8.7 mmHg and 8.5 mmHg, with a systolic pressure response of 58% and 65%, respectively. HBPM had no additional benefits. Eprosartan was well tolerated, with the majority of adverse events being mild to moderate. CONCLUSIONS: Eprosartan alone or in combination with hydrochlorothiazide was highly effective and safe in lowering blood pressure, notably SBP, in older subjects with mild to moderate hypertension.

Acrylates↗
PubMed2003

The rating of pre-clerkship examination questions by postgraduate medical students: an assessment of quality and relevancy to medical practice.

OBJECTIVE: To determine whether postgraduate students are able to assess the quality of undergraduate medical examinations and to establish whether faculty can use their results to troubleshoot the curriculum in terms of its content and evaluation. SUBJECTS: First and second year family medicine postgraduate students. MATERIALS: A randomly generated sample of undergraduate medical examination questions. METHODS: Postgraduate students were given two undergraduate examinations which included questions with an item difficulty (ID) > 0.60. The students answered and then rated each question on a scale of 1-7. RESULTS: The percentage of postgraduate students answering each question correctly correlated significantly with the average perceived relevance (Examination 1: r=0.372; P < 0.05; Examination 2: r=0.458; P < 0.05). Questions plotted for average postgraduate/undergraduate performance ratio versus the average perceived relevance were significantly correlated (Examination 1: r=0.462; P < 0.01; Examination 2: r=0.458; P < 0.05). CONCLUSIONS: This study offers a method of validating question appropriateness prior to examination administration. The design has the potential to be used as a model for determining the relevancy of a medical curriculum.

Clinical Clerkship↗
PubMed2003

The Supplemental Instruction Project: peer-devised and delivered tutorials.

The purpose of this study was to determine whether student devised and delivered supplemental instruction is beneficial and acceptable to first-year medical students. A student-run Supplemental Instruction Project (SIP) was developed and delivered by second-year medical students and offered free of charge to all first-year medical students at Memorial University of Newfoundland taking the Integrated Study of Disease I course in 1999 and again in 2000. Small-group tutorials focused on subject material that second-year medical students identified as 'difficult'. Five 60- to 90-minute sessions covering topics in cardiology, nephrology and respirology were offered. Student and tutor perceptions about the project were collected using anonymous questionnaires. Students were quizzed before and after each tutorial session. Post-tutorial quiz scores were significantly greater than pre-tutorial scores. Student and tutor perceptions of SIP were positive. It is concluded that the SIP is an acceptable, practical and effective method to supplement delivery of challenging material to first-year medical students.

Attitude of Health Personnel↗
PubMed2002

The 2001 Canadian recommendations for the management of hypertension: Part one--Assessment for diagnosis, cardiovascular risk, causes and lifestyle modification.

OBJECTIVE: To provide updated, evidence-based recommendations for the assessment of the diagnosis, cardiovascular risk, identifiable causes and lifestyle modifications for adults with high blood pressure. OPTIONS: For persons in whom a high blood pressure value is recorded, hypertension is diagnosed based on the appropriate measurement of blood pressure, the level of the blood pressure elevation and the duration of follow-up. In addition, the presence of concomitant vascular risk factors, target organ damage and established atherosclerotic diseases must be assessed to determine the urgency, intensity and type of treatment. For persons receiving a diagnosis of hypertension, defining the overall risk of adverse cardiovascular outcomes requires an assessment of concomitant vascular risk factors, including laboratory testing, a search for target organ damage and an assessment for modifiable causes of hypertension. Home and ambulatory blood pressure assessment and echocardiography are options for selected patients. OUTCOMES: The outcomes were: the identification of persons at increased risk of adverse cardiovascular outcomes; the quantification of overall cardiovascular risk; and the identification of persons with potentially modifiable causes of hypertension. EVIDENCE: Medline searches were conducted from one year before the period of the last revision of the Canadian recommendations for the management of hypertension (May 1999 to May 2001). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. Identified articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts. In addition to an update of the previous year's review, new sections on assessing overall cardiovascular risk and endocrine causes are provided. VALUES: A high value was placed on the identification of persons at increased risk of cardiovascular morbidity and mortality, and of persons with identifiable causes of hypertension. BENEFITS, HARMS AND COSTS: The identification of persons at higher risk of cardiovascular disease will permit counseling for lifestyle manoeuvres and introduction of antihypertensive drugs to reduce blood pressure for patients with sustained hypertension. The identification of specific causes of hypertension may permit the use of cause-specific interventions. In certain subgroups of patients, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity or mortality. RECOMMENDATIONS: The present document contains recommendations for the assessment of the diagnosis, cardiovascular risk, identifiable causes and lifestyle modifications for adults with high blood pressure. These include the accurate measurement of blood pressure, criteria for the diagnosis of hypertension and recommendations for follow-up, assessment of overall cardiovascular risk, routine and optional laboratory testing, assessment for renovascular and endocrine causes, home and ambulatory blood pressure monitoring, the role of echocardiography and lifestyle modifications. VALIDATION: All recommendations were graded according to the strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported. These guidelines will be updated annually. ENDORSEMENT: These guidelines are endorsed by the Canadian Hypertension Society, The Canadian Coalition for High Blood Pressure Prevention and Control, The College of Family Physicians of Canada, The Heart and Stroke Foundation of Canada, The Adult Disease Division and Bureau of Cardio-Respiratory Diseases and Diabetes at the Centre for Chronic Disease Prevention and Control, Health Canada.

Antihypertensive Agents↗
PubMedDate not supplied

Hypertension surveillance in Canada: minimum standards for assessing blood pressure in surveys.

The last Canadian survey that accurately assessed hypertension treatment and control is over 12 years old. The survey indicated that only 13% of adults with hypertension were treated and controlled. Statistics Canada has announced a new survey that will measure health risks in 2007-2008. A committee of hypertension and survey experts was formed to provide recommendations to ensure the survey would address the minimum surveillance needs of the hypertension community. The committee made several innovative recommendations to improve the reproducibility and standardization of blood pressure assessment. In particular, it was recommended to adopt oscillometric measurement and to have measurements conducted in the absence of study personnel. Continued use of standard Canadian survey questions to assess awareness and treatment of hypertension was recommended to allow comparison with prior surveys. It was also recommended that Canada adopt a specific question on lifestyle changes. The new survey will allow the Canadian hypertension community, and in particular the Canadian Hypertension Education Program, to evaluate the effectiveness of current programs for prevention, treatment and control of hypertension and to revise our strategies based on the results.

Adult↗