Guideline No. 417: Prevention of Venous Thromboembolic Disease in Gynaecological Surgery

OBJECTIVE

The primary objective of this clinical practice guideline is to provide gynaecologists with an algorithm and evidence to guide the use of thromboprophylaxis in gynaecological surgery.

TARGET POPULATION

All patients undergoing gynaecological surgery for benign or malignant indications.

BENEFITS, HARMS, AND COSTS

The implementation of this guideline will benefit patients undergoing gynaecological surgery and provide physicians with a standard algorithm for the use of perioperative thromboprophylaxis.

EVIDENCE

The following search terms were entered into MEDLINE, Google Scholar, and Cochrane in 2017 and 2018: VTE, PE, DVT, thromboprophylaxis, gynaecological surgery, heparin, graduated compression stocking, intermittent pneumatic stocking, obesity, pediatrics, minimally invasive surgery, heparin induced thrombocytopenia, regional anesthesia). Articles included were randomized controlled trials, meta-analyses, systematic reviews, and observational studies. Additional publications were identified from the reference lists of these articles. There were no date limits, but search results were limited to English language articles only. Searches were updated and incorporated into the guideline up to September 2018.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and weak recommendations).

INTENDED USERS

Gynaecologists and other members of the surgical team. RECOMMENDATIONS (GRADE RATINGS IN PARENTHESES).

Tranexamic Acid Use in the Postpartum Period Since the WOMAN Trial: A retrospective chart review

OBJECTIVE

To analyze the use of tranexamic acid (TXA) in postpartum patients since the WOMAN trial.

METHODS

A retrospective recrods review was conducted from May 2017 to March 2020 at a tertiary care centre to identify all patients who received TXA for postpartum bleeding. The primary outcome was to identify the proportion of patients who received TXA as per World Health Organization guidelines using the results of the WOMAN trial.

RESULTS

A total of 231 patients were included in our analysis. Use increased over time with 18 patients in 2017, 51 in 2018, and 134 in 2019 receiving TXA. In all, 203 patients (87.9%) received TXA within recommended guidelines, and these patients were less likely to require surgery or interventional radiology (12.3% vs. 42.9%, P < 0.001) or blood transfusion (23.6% vs. 42.9%, P = 0.030), and they had a lower likelihood of overall adverse events (LR 1.62 (1.6) vs. 2.60 (2.0), P = 0.024). TXA was commonly used as the first-line agent for postpartum bleeding (48.9% of patients), and was administered at cesarean section (77.0%) and when estimated blood loss did not meet criteria for "true" postpartum hemorrhage (41.6% of patients). Use of TXA as the first medication was associated with fewer adverse outcomes overall than misoprostol (P = 0.035). A shorter time to administration of the first medication was associated with shorter postpartum admission time (P = 0.042).

CONCLUSIONS

The majority of patients received TXA within guidelines and experience fewer adverse outcomes. Further study is needed to identify the best order of TXA administration with additional uterotonics and whether TXA should be used prophylactically in some groups for postpartum bleeding.

Depression in midlife women attending a menopause clinic is associated with a history of childhood maltreatment

A growing body of literature has suggested that the perimenopause and the early postmenopausal years are associated with an increased risk of experiencing symptoms of depression and the development of first-onset and recurrent episodes of major depressive disorder. Multiple risk factors have been identified, including stressful life events and lower socioeconomic status, as well as early life adversity. The objective of the current study was to characterize the influence of early life childhood maltreatment and incident depression among women experiencing bothersome menopausal symptoms. Participants were recruited from two university-affiliated specialty clinics caring for women with bothersome menopausal symptoms. Assessments included the Childhood Trauma Questionnaire (CTQ), the Center for Epidemiological Studies - Depression (CES-D) scale and the Greene Climacteric Scale. Findings from this cross-sectional study indicate that adverse childhood experiences, as measured using the CTQ, were highly prevalent among women seeking care for bothersome menopausal symptoms (66%). Further, a greater score on the CTQ was significantly associated with higher CES-D scores, as well as with a greater burden of menopausal symptoms, after adjusting for confounding. Our findings lend support to the growing body of literature suggesting that early life stress affects mental health well into adulthood.

245 Sleep and cortical thickness are influenced by surgical menopause

Introduction

Early loss of 17β-estradiol (E2), as experienced by women with bilateral salpingo-oophorectomy (BSO; removal of ovaries and fallopian tubes), is associated with increased prevalence of sleep disorders and greater Alzheimer’s disease (AD) risk. In older adults, poor sleep heightens AD risk; hypoxia increases markers for incipient AD, including circulating Aβ, and is linked to prefrontal cortical thinning. Thus, we wondered: 1) if this at-risk population of middle-aged women with BSO had sleep hypoxia, measured by oxygen desaturation, and 2) whether this related to decreased prefrontal cortical thickness in women taking and not taking estradiol therapy (ET).

Methods

Sleep and percent oxygen desaturation (SPO2%) were measured via at-home polysomnography (TEMEC). Prefrontal cortical thickness was obtained from T1-weighted structural scans using the CIVET pipeline. We recruited middle-age women with BSO, some of whom were taking ET (BSO+ET; n=15), and some not (BSO; n=15). We compared their sleep and cortical thickness with that of age and education-matched premenopausal controls (AMC; n=18).

Results

Women with BSO (BSO, BSO+ET) had lower minimum SPO2% values than AMC, and thinner right medial orbitofrontal (rmOF) cortices. There was a trend for women with BSO to have lower average SPO2% than AMC. Analyses separating groups based on ET therapy status (BSO vs BSO+ET vs AMC) revealed only trending differences between groups, such that women with BSO tended to have lower minimum SPO2% and thinner rmOF cortices than AMC.

Conclusion

These preliminary results suggest early loss of E2 due to BSO may drive greater drops in SPO2% in middle-age women, and may be related to reduced prefrontal cortical thickness. This study is the first to show hypoxia in women with BSO.

Support (if any)

Ontario Graduate Scholarship Award (to LG), Alzheimer’s Association Research Fellowship (co-sponsored by Brain Canada Foundation; AARF-17-504715 to NJG), Alzheimer’s Society Canada Postdoctoral Fellowship (to AA), Canadian Institutes of Health Research (CIHR) Masters Award (to LG, AB, and RR), Wilfred and Joyce Posluns Chair in Women’s Brain Health and Aging (from the Posluns Family Foundation, CIHR, Ontario Brain Institute, and Alzheimer Society of Canada; WJP-150643 to GE)

038 Sleep and Hippocampal Function during an Associative Memory Task are Influenced by Surgical Menopause at Midlife

Introduction

17β-estradiol loss is related to Alzheimer’s disease (AD) risk factors, including disordered sleep and associative memory decrements. Women have higher risk for AD than men, and those with mid-life 17β-estradiol loss due to surgical menopause, including bilateral salpingo-oophorectomy (BSO) before age 48, have even higher risk. We wondered whether sleep and associative memory in women with BSO (mean age 44–46) would be comparable to those with spontaneous/natural menopause (SM; mean age 57), and whether 17β-estradiol-based hormone therapy (ET) might mitigate these effects.

Methods

We assessed sleep using the average of three nights of portable polysomnography (Temec) in women with BSO either taking ET (BSO+ET; n=16), or not (BSO; n=18), and in older spontaneously menopausal women (SM; n=14). Using EEG (Fp1-Fp2), we obtained sleep staging automatically (Neurobit Technologies). Participants also completed a face-name associative memory task during functional magnetic resonance imaging. Recognition accuracy and brain activation during encoding were measured.

Results

BSO exhibited reduced sleep efficiency compared to BSO+ET. For BSO, there was no relationship between percent of total sleep time in N3 and hippocampal activation during associative encoding, even though percent of total sleep time in N3 was negatively associated with hippocampal activation during associative encoding in BSO+ET. For all groups, including BSO, lower latency to consolidated N3 correlated with better associative memory accuracy. There were no group differences in associative memory accuracy. In contrast to BSO, SM showed significantly longer latency to consolidated N3 than BSO+ET.

Conclusion

Younger women with BSO have comparable sleep to older women in SM. In younger women with BSO, ET improves sleep efficiency. Further, while associative memory may be disrupted by increased latency to consolidated N3 in all women, BSO and BSO+ET showed similar associative memory accuracy and latency to consolidated N3. Only BSO+ET exhibited a significant correlation between hippocampal activity during associative encoding and time spent in N3, indicating that ET may support the negative relationship between N3 and hippocampal function. Overall, ET in younger women with BSO potentially ameliorates poor sleep and associative memory decrements.

Support (if any)

Alzheimer’s Association/Brain Canada Foundation: AARF-17-504715; Wilfred and Joyce Posluns Chair in Women’s Brain Health and Aging

Transfers of lower quality embryos based on morphological appearance result in appreciable live birth rates: a Canadian center's experience

Objective

To determine the reproductive outcomes resulting from transfer of lower-grade blastocysts to support the practice of cryopreserving and transferring lower-grade embryos.

Design

Retrospective chart review.

Setting

Single infertility center.

Patient(s)

Women who have undergone a fresh (n = 570) or frozen (n = 885) transfer of a single blastocyst embryo between December 2013 and December 2018.

Intervention(s)

None.

Main Outcome Measure(s)

The primary outcome was live birth rate. The secondary outcomes included implantation rate, ongoing pregnancy rate, associations with inner cell mass (ICM) and trophectoderm epithelium (TE) grades determined by morphological assessment, and antenatal/perinatal complications.

Results

Reproductive outcomes directly correlated with embryo quality. Transfers of AA embryos resulted in a 41.4% live birth rate compared to 31.1% for BB embryos and 13.3% for CC embryos. The TE grade was significantly associated with the live birth rate. Embryos with a TE grade of “B” had an odds ratio of 0.677 and embryos with a TE grade of “C” had an odds ratio of 0.394 compared to embryos with a TE grade of “A” for live birth.

Conclusion

Embryos with a TE “C” grade should be considered for transfer and cryopreservation, as they are shown to result in appreciable live birth rates. Such treatment should involve a thorough discussion with patients, however, as these live birth rates are significantly lower than those associated with higher-grade embryos.

Evaluation of a Community-Based Self-Management Program to Increase Access to Rehabilitation for People Living with HIV

We qualitatively evaluated a novel educational program to help people living with HIV understand the role of rehabilitation, facilitate access to rehabilitation, and promote self-management of chronic disease in Canada. The program incorporated components of self-efficacy, client-centered care, peer education, and problem-based learning. Delivery of the community-engaged program was viewed as feasible and acceptable; however, a flexible delivery model was deemed important. Perceived learning was related to rehabilitation, advocacy, and taking responsibility for one's health. A co-leader model and access to online resources were strengths. Future work should assess the ability to apply advocacy knowledge and skills to access rehabilitation services.

Pregnant Canadians' Perceptions About the Transmission of Cannabis in Pregnancy and While Breastfeeding and the Impact of Information From Health Care Providers on Discontinuation of Use

OBJECTIVE

Rates of cannabis use during pregnancy and while breastfeeding are increasing in Canada. Some observational studies have found associations between cannabis use in pregnancy and low birthweight, preterm labour, and admission to the intensive care unit. This study aimed to evaluate women's perceptions about transmission of cannabis to the fetus, and whether receiving information from a health care provider influenced their decision to stop using cannabis during pregnancy.

METHODS

Pregnant women presenting to obstetrical, midwifery, and family practice clinics in the greater Hamilton, Ontario area were asked to complete an anonymous survey. Chi-square tests were used to investigate whether patient knowledge was influenced by health care providers or by self-directed learning and if this information influenced their decision to discontinue cannabis use.

RESULTS

Of the 478 women surveyed, the vast majority perceived that cannabis is transmitted to the fetus during pregnancy and to the infant while breastfeeding (94.3% and 91.2%, respectively). The majority of women (99%) indicated that the advent of cannabis legalization did not influence their choice to use cannabis in pregnancy. Women who continued to use cannabis during pregnancy were more likely to report receiving information on cannabis from a health care provider (52%) than those who chose to discontinue use in pregnancy (35%) (P = 0.035).

CONCLUSIONS

In our study, the proportion of pregnant women who understood that cannabis could be transmitted to the fetus in utero and to the infant via breastmilk was high. Despite this, 4.2% of women reported that they continued to use cannabis in pregnancy. More work is needed to understand why some women continue to use cannabis in pregnancy despite being informed of its risks.

Trajectories of Episodic Disability in People Aging with HIV: A Longitudinal Qualitative Study

People living with HIV may experience disability which is episodic in nature, characterized by periods of wellness and illness. The purpose of this longitudinal qualitative study was to understand how the episodic nature of HIV and the associated uncertainty shape the disability experience of older adults living with HIV over time. Fourteen men and 10 women who were HIV positive and over 50 years (mean age: 57 years; range: 50-73) participated in 4 interviews over 20 months. Longitudinal analyses of the transcribed interviews identified 4 phenotypes of episodic disability over time: decreasing, increasing, stable, or significant fluctuations. Although all participants experienced uncertainty, acceptance and optimism were hallmarks of those whose phenotypes were stable or improved over time. Understanding a person's episodic trajectory may help to tailor interventions to promote stability, mitigate an upward trajectory of increasing disability, and increase the time between episodes of illness.

Design features of a guideline implementation tool designed to increase awareness of a clinical practice guide to HIV rehabilitation: A qualitative process evaluation

RATIONALE, AIMS, AND OBJECTIVES

A comprehensive electronic guide (e-module) describing an interprofessional, evidence-informed approach to HIV rehabilitation was developed as an education resource for rehabilitation professionals. We developed a guideline implementation tool, consisting of a 10-week, case-based education intervention delivered by email, that was perceived to increase rehabilitation professionals' (occupational therapists (OTs), physical therapists (PTs), and speech language pathologists (SLPs)) knowledge and confidence to apply best practices in HIV rehabilitation. This study aimed to increase understanding of how the design of the guideline implementation tool facilitated increased awareness of and access to the e-module among rehabilitation professionals.

METHODS

We conducted a single group intervention study with rehabilitation professionals in Canada and the United Kingdom. Six case studies targeting HIV pathophysiology and associated conditions, an interprofessional approach to rehabilitation assessment and treatment, and psychosocial issues experienced by people living with HIV, were emailed to participants at 2-week intervals. Individual semi-structured interviews were conducted post-intervention. Interview transcripts were analysed using a descriptive qualitative approach.

RESULTS

Twenty-six individuals (17 from Canada, and 9 from the UK; 16 PTs, 7 OTs, 3 SLPs) were interviewed. One main theme related to design features of the intervention that facilitated learning and access to the e-module emerged. Subthemes highlighted features of the case-based intervention, including technical feasibility, terminology, formatting and layout, hyperlinks, number and frequency of case studies, and diverse and realistic case scenarios relevant to the learner's practice, that participants described as facilitating access to information and learning.

CONCLUSION

Electronically administered case studies were perceived as complementary knowledge tools that increased access to an evidence-informed guide to HIV rehabilitation. Findings provide guidance on using case studies as a guideline implementation tool to facilitate access to information and related resources to optimize learning.

Two approaches to longitudinal qualitative analyses in rehabilitation and disability research

Purpose: Although relatively unknown within the field of rehabilitation, qualitative longitudinal research is ideal for rehabilitation and disability research that aims to understand health-related challenges over time. We describe the strengths and challenges of longitudinal qualitative research using two concrete examples.Materials and methods: Qualitative longitudinal research often involves in-depth interviews of participants on multiple occasions over time. Analytic approaches are complex, summarizing data both cross-sectionally and longitudinally. We present two detailed analytic approaches used in research with people living with HIV in Zambia and Canada.Results: Our experiences provide three recommendations. First, development of the initial analytic coding framework should include both inductive and deductive approaches. Second, given the large quantity of data generated through longitudinal qualitative research, it is important to proactively develop strategies for data analysis and management. Third, as retention of participants is challenging over time, we recommend the use of a consistent interviewer over the duration of the study to promote a trusting relationship.Conclusions: Longitudinal qualitative research has much to offer researchers and can provide clinicians with insights on the challenges of living with chronic and episodic disability. The flexibility in analytic approaches allows for diverse strategies to best address the rehabilitation and disability research questions and allow for insights into living with disability over time.

Qualitative longitudinal study of episodic disability experiences of older women living with HIV in Ontario, Canada

OBJECTIVES

To examine the episodic disability experiences of older women living with HIV over time.

DESIGN

Qualitative longitudinal study, conducting semistructured in-depth interviews on four occasions over a 20-month time frame. Inductive thematic analyses were conducted cross-sectionally and longitudinally.

SETTING

Participants were recruited from HIV community organisations in Canada.

PARTICIPANTS

10 women aged 50 years or older living with HIV for more than 6 years.

RESULTS

Two major themes related to the episodic nature of the women's disability. Women were living with multiple and complex sources of uncertainty over time including: unpredictable health challenges, worrying about cognition, unreliable weather, fearing stigma and the effects of disclosure, maintaining housing and adequate finances, and fulfilling gendered and family roles. Women describe strategies to deal with uncertainty over time including withdrawing and limiting activities and participation and engaging in meaningful activities.

CONCLUSIONS

This longitudinal study highlighted the disabling effects of HIV over time in which unpredictable fluctuations in illness and health resulted in uncertainty and worrying about the future. Environmental factors, such as stigma and weather, may put older women living with HIV at a greater risk for social isolation. Strategies to promote dealing with uncertainty and building resilience are warranted.

'I'm still here, I'm still alive': Understanding successful aging in the context of HIV

As people living with HIV (PLWH) live longer, increased understanding of individuals' values and perceptions of successful aging can assist health providers in working with PLWH to set meaningful goals as they age. The purpose of this qualitative study was to understand how PLWH define successful aging and their perceptions of contributors to successful aging. Fourteen men and ten women over the age of 50 years (mean age 57 years; mean time since diagnosis 18 years) participated in individual interviews. Interviews were analyzed using directed content analysis. Six themes emerged: accepting limitations, staying positive, maintaining social supports, taking responsibility, living a healthy lifestyle, and engaging in meaningful activities. The participants emphasized individual control. This highlights the importance of working with PLWH to understand their values and aspirations, and create patient-centered goals. From a research perspective this reinforces calls to include the subjective experiences of older adults in developing successful aging criteria.

Collaborative development of an educational resource on rehabilitation for people living with HIV

OBJECTIVE

The objective of this study is to describe the collaborative development of a rehabilitation guide for people living with human immunodeficiency virus (HIV) which was adapted from an online resource for clinicians.

METHODS

We adapted a comprehensive evidence-informed online clinical resource for people living with HIV using a three-phase participatory process. In Phase 1, we interviewed 26 clinicians and 16 people living with HIV to gather recommendations on how to adapt and format the content to benefit people living with HIV. In Phase 2, we adapted the patient education resource using the recommendations that emerged from Phase 1. Phase 3 consisted of comprehensive stakeholder review of the revised resource on the adaptability, usability, communicability, and relevance of the information. Stakeholders participated in an interview to obtain in-depth information on their perspectives. Transcribed interviews underwent qualitative content analysis.

RESULTS

Stakeholders indicated that the e-guide had utility for people living with HIV, community HIV service organizations, and care providers.

CONCLUSION

Engaging people living with HIV resulted in a more relevant and meaningful resource that incorporated patients' values, needs, and preferences.

IMPLICATIONS

Involving multiple stakeholders and user groups in the adaptation and evaluation of online patient education resources can assist in meeting patients' needs through increasing the relevance, organization and presentation of the content, and incorporating patients' values and needs. Implications for Rehabilitation Online patient education resources should be adapted in order to maximize relevance and meaningfulness to patients. Involving multiple stakeholders in the adaptation and evaluation of online patient education resources can assist in meeting patients' needs. Involving multiple stakeholders increases the relevance, organization and presentation of the content and allows the incorporation of patient values and needs. This collaborative approach with an emphasis on meaningful participation of patients and community may be of interest to others interested in promoting knowledge translation.

Recommendations on breast cancer screening and prevention in the context of implementing risk stratification: impending changes to current policies

In recent years, risk stratification has sparked interest as an innovative approach to disease screening and prevention. The approach effectively personalizes individual risk, opening the way to screening and prevention interventions that are adapted to subpopulations. The international perspective project, which is developing risk stratification for breast cancer, aims to support the integration of its screening approach into clinical practice through comprehensive tool-building. Policies and guidelines for risk stratification-unlike those for population screening programs, which are currently well regulated-are still under development. Indeed, the development of guidelines for risk stratification reflects the translational aspects of perspective. Here, we describe the risk stratification process that was devised in the context of perspective, and we then explain the consensus-based method used to develop recommendations for breast cancer screening and prevention in a risk-stratification approach. Lastly, we discuss how the recommendations might affect current screening policies.

Emergence of spatial behavioral function and associated mossy fiber connectivity and c-Fos labeling patterns in the hippocampus of rats

Improvement on spatial tasks is observed during a late, postnatal developmental period (PND18 – PND24).  The purpose of the current work was 1) to determine whether the emergence of spatial-behavioral function was based on the ability to generate appropriate behavioral output; 2) to assess whether mossy fiber connectivity patterns preceded the emergence of spatial-behavioral function; 3) to explore functional changes in the hippocampus to determine whether activity in hippocampal networks occurred in a training-dependent or developmentally-dependent fashion.  To these ends, male, Long Evans rats were trained on a spatial water or dry maze task for one day (PND16, PND18 or PND20) then euthanized.  Training on these 2 tasks with opposing behavioral demands (swimming versus exploration) was hypothesized to control for behavioral topology.  Only at PND20 was there evidence of spatial-behavioral function for both tasks.  Examination of synaptophysin staining in the CA3 region (i.e., mossy fiber projections) revealed enhanced connectivity patterns that preceded the emergence of spatial behavior.  Analysis of c-Fos labeling (functional changes) revealed developmentally-dependent increases in c-Fos positive cells in the dentate gyrus, CA3 and CA1 regions whereas training-dependent increases were noted in the CA3 and CA1 regions for the water-maze trained groups.  Results suggest that changes in mossy fiber connectivity in association with enhanced hippocampal functioning precede the emergence of spatial behavior observed at PND20.  The combination of neuroanatomical and behavioural results confirms the hypothesis that this time represents a sensitive period for hippocampal development and modification and the emergence of spatial/ cognitive function.

Aging with HIV: a model of disability

The purpose of this qualitative study was to develop a theoretical model describing the disability experienced by older adults living with HIV. Forty nine HIV positive men and women over the age of 50 years participated in in-depth qualitative interviews. Transcribed interviews were analyzed using grounded theory techniques. Uncertainty or worrying about the future was at the core of the model. Components of disability including symptoms and impairments, difficulties with day to day activities and challenges to social participation were experienced in the context of extrinsic or environmental factors (social support, stigma) and intrinsic contextual factors (positive living strategies, age). Time was an overarching component of the model. The model suggests areas for interventions to prevent or reduce disability related to the consequences of aging with HIV and improve overall quality of life.

Aging with HIV and disability: the role of uncertainty

Due to advances in treatment, people with HIV are living longer and developing disabilities related to the virus, adverse side effects of medications, and aging. Illness-related uncertainty has been shown to contribute to disablement; however, there is little understanding of the uncertainties related to aging with HIV. The purpose of this research was to describe the contribution of uncertainty to the disability experienced by older adults living with HIV. Forty-nine men and women living with HIV and 50 years or older participated in in-depth qualitative interviews exploring various aspects of social participation and disability. Transcriptions of the interviews were analyzed using a grounded theory approach. Age-related uncertainties were described in the following themes: source of health challenge; health providers' age-related knowledge and skills; financial uncertainty; transition to retirement; appropriate long-term housing, and uncertainty over who would care for them. While not directly attributable to aging, the episodic nature of HIV left many with uncertainties related to when their next episode of illness would occur and often resulted in an inability to plan in advance. Results highlight the need to focus on the notion of successful and positive aging with the view to identifying effective interventions that reduce disability and enhance the overall health of older adults with HIV. This work builds on previous studies highlighting the role of uncertainty in the disability experience by identifying age-related components specific to older adults aging with HIV.

Heat Synch: Inter- and Independence of Body-Temperature Fluctuations and Brain-State Alternations in Urethane-Anesthetized Rats

During sleep, warm-blooded animals exhibit cyclic alternations between rapid-eye-movement (REM) and nonrapid-eye-movement (non-REM) states, characterized by distinct patterns of brain activity apparent in electroencephalographic (EEG) recordings coupled with corresponding changes in physiological measures, including body temperature. Recently we have shown that urethane-anesthetized rats display cyclic alternations between an activated state and a deactivated state that are highly similar in both EEG and physiological characteristics to REM and non-REM sleep states, respectively. Here, using intracranial local field potential recordings from urethane-anesthetized rats, we show that brain-state alternations were correlated to core temperature fluctuations induced using a feedback-controlled heating system. Activated (REM-like) states predominated during the rising phase of the temperature cycle, whereas deactivated (non-REM-like) states predominated during the falling phase. Brain-state alternations persisted following the elimination of core temperature fluctuations by the use of a constant heating protocol, but the timing and rhythmicity of state alternations were altered. In contrast, thermal fluctuations applied to the ventral surface (and especially the scrotum) of rats in the absence or independently of core temperature fluctuations appeared to induce brain-state alternations. Heating brought about activated patterns, whereas cooling produced deactivated patterns. This shows that although alternations of sleeplike brain states under urethane anesthesia can be independent of imposed temperature variations, they can also be entrained through the activation of peripheral thermoreceptors. Overall, these results imply that brain state and bodily metabolism are highly related during unconsciousness and that the brain mechanisms underlying sleep cycling and thermoregulation likely represent independent, yet coupled oscillators.

Angiotensin-converting enzyme inhibitor-associated angioedema is characterized by a slower degradation of des-arginine(9)-bradykinin

Angioedema (AE) is a rare but potentially life-threatening side effect of therapy with inhibitors of angiotensin-converting enzyme (ACE), the main bradykinin (BK)- inactivating metallopeptidase in humans. The pathogenesis of ACE inhibitor (ACEi)- associated AE (AE+) is presently unknown, although there is increasing evidence of a kinin role. We analyzed the metabolism of endogenous BK (B(2) receptor agonist) and its active metabolite, des-Arg(9)-BK (B(1) receptor agonist), in the presence of an ACEi during in vitro contact activation of plasma from hypertensive patients (n = 39) who presented AE+. Kinetic parameters were compared with those measured in a control group (AE-) of hypertensive patients (n = 39) who never manifested any acute or chronic side effects while treated with an ACEi. The different kinetic parameters were analyzed using a mathematical model (y = k t(alpha) e(-beta t)) previously applied to a normal, healthy population. The slope of BK degradation, but not its formation from high-molecular-weight kininogen, was lower in AE+ patients when compared with the AE- controls. des-Arg(9)-BK accumulation during the kinetic measurements was significantly higher in AE+ plasma. This accumulation of the B(1) agonist in AE+ patients paralleled its half-life of degradation. In conclusion, our results show, for the first time, that an abnormality of endogenous des-Arg(9)-BK degradation exists in the plasma of patients with ACEi-associated AE, suggesting that its pathogenetic mechanism lies in the catabolic site of kinin metabolism.

Biochemical basis of angioedema associated with recombinant tissue plasminogen activator treatment: an in vitro experimental approach

BACKGROUND

Angioedema has been reported during recombinant tissue plasminogen activator (rtPA) treatment of acute ischemic stroke, often with concomitant use of angiotensin I-converting enzyme inhibitor treatment. Angioedema has been partly attributed to the nonapeptide bradykinin (BK), although its precise role has been poorly documented until now. The purposes of this report are 2-fold. First, we sought to define and characterize the in vitro kinin-forming capacity of rtPA when incubated with human plasma at a concentration within the therapeutic concentration range of rtPA attained in blood in vivo during fibrinolysis. Second, we sought to define the mechanism by which rtPA liberates BK from purified human single-chain high-molecular-weight kininogen, a key constituent of the contact system of plasma and the precursor of BK.

SUMMARY OF REPORT

When incubated with human plasma, in the presence of an angiotensin I-converting enzyme inhibitor, rtPA generates BK, which is further metabolized to des-Arg9-BK. The quantity of kinins generated by rtPA is similar to that observed during the activation of the contact system of plasma with a negatively charged surface, suggesting that it is physiologically relevant. The total amount of des-Arg9-BK liberated during the incubation period depends on the aminopeptidase P activity, its main degrading peptidase. Additionally, incubations using purified proteins of the fibrinolytic and the contact system pathways show that the rtPA kinin-forming capacity is mediated by plasmin.

CONCLUSIONS

We conclude that rtPA used in vitro at a therapeutic concentration has the capacity to generate significant quantities of kinins from human plasma. This kinin-forming activity depends on the activation of the fibrinolytic pathway. These data suggest that angioedema associated with rtPA treatment of ischemic stroke results directly from plasmin-mediated release of BK.

Bradykinin and des-Arg(9)-bradykinin metabolic pathways and kinetics of activation of human plasma

In the serum of 116 healthy individuals, exogenous bradykinin (BK) half-life (27 +/- 10 s) was lower than that of des-Arg(9)-BK (643 +/- 436 s) and was statistically different in men compared with women. The potentiating effect of an angiotensin-converting enzyme (ACE) inhibitor was, however, more extensive for BK (9.0-fold) than for des-Arg(9)-BK (2.2- fold). The activities of ACE, aminopeptidase P (APP), and kininase I were respectively 44 +/- 12, 22 +/- 9, and 62 +/- 10 nmol x min(-1) x ml(-1). A mathematical model (y = kt(alpha)e(-beta t), t > 0), applied to the BK kinetically released from endogenous high-molecular-weight kininogen (HK) during plasma activation in the presence of an ACE inhibitor, revealed a significant difference in the rate of formation of BK between men and women. For des-Arg(9)-BK, the active metabolite of BK, the rate of degradation was higher in women compared with men, correlating significantly with serum APP activity (r(2) = 0.6485, P < 0.001). In conclusion, these results constitute a basis for future pathophysiological studies of inflammatory processes where activation of the contact system of plasma and the kinins is involved.

Effects of the vasopeptidase inhibitor omapatrilat on cardiac endogenous kinins in rats with acute myocardial infarction

The purposes of this study were to evaluate and to compare the effects of simultaneous angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP) inhibition by the vasopeptidase inhibitor omapatrilat (1 mg. kg(-1). day(-1)) with those of the selective ACE inhibitor enalapril (1 mg. kg(-1). day(-1)) on survival, cardiac hemodynamics, and bradykinin (BK) and des-Arg(9)-BK levels in cardiac tissues 24 h after myocardial infarction (MI) in rats. The effect of the co-administration of both B(1) and B(2) kinin receptor antagonists (2.5 mg. kg(-1). day(-1) each) with metallopeptidase inhibitors was also evaluated. The pharmacological treatments were infused subcutaneously using micro-osmotic pumps for 5 days starting 4 days before the ligation of the left coronary artery. Immunoreactive kinins were quantified by highly sensitive and specific competitive enzyme immunoassays. The post-MI mortality of untreated rats with a large MI was high; 74% of rats dying prior to the hemodynamic study. Mortality in the other MI groups was not significantly different from that of the untreated MI rats. Cardiac BK levels were not significantly different in the MI vehicle-treated group compared with the sham-operated rats. Both omapatrilat and enalapril treatments of MI rats significantly increased cardiac BK concentrations compared with the sham-operated group (P < 0.05). However, cardiac BK levels were significantly increased only in the MI omapatrilat-treated rats compared with the MI vehicle-treated group (P < 0.01). Cardiac des-Arg(9)-BK concentrations were not significantly modified by MI, and MI with omapatrilat or enalapril treatment compared with the sham-operated group. The co-administration of both kinin receptor antagonists with MI omapatrilat- and enalapril-treated rats had no significant effect on cardiac BK and des-Arg(9)-BK levels. Thus, the significant increase of cardiac BK concentrations by omapatrilat could be related to a biochemical or a cardiac hemodynamic parameter on early (24 h) post-MI state.

Anomaly of the des-Arg9-bradykinin metabolism associated with severe hypotensive reactions during blood transfusions: a preliminary study

BACKGROUND

Severe hypotensive reactions have been described after the transfusion of platelets or red cells through negatively-charged bedside white cell-reduction filters. The possibility of a role for bradykinin (BK) in the genesis of these reactions has been raised.

STUDY DESIGN AND METHODS

To understand if an anomaly of BK metabolism is associated with these reactions, the metabolism of BK and des-Arg9-BK was studied in the sera of four patients who presented with a severe hypotensive transfusion reaction. Tests were performed in the absence and the presence of complete in vitro inhibition of angiotensin-converting enzyme (ACE) activity by enalaprilat.

RESULTS

In the presence of ACE inhibition (enalaprilat), the half-life (t1/2) of BK measured in the sera of patients who presented with a severe hypotensive transfusion reaction (361 +/- 90 sec) was not significantly different from that measured in the sera of normal controls (249 +/- 16 sec). In the presence of ACE inhibition (enalaprilat), the t1/2 of des-Arg9-BK was significantly greater in patients who presented with a severe hypotensive transfusion reaction (1549 +/- 319 sec) than in normal controls (661 +/- 38 sec) (p < 0.001).

CONCLUSION

A metabolic anomaly mainly affecting the degradation of des-Arg9-BK could be responsible for its accumulation in vivo. Des-Arg9-BK could be responsible, at least in part, for severe hypotensive transfusion reactions.

Serum metabolism of bradykinin and des-Arg9-bradykinin in patients with angiotensin-converting enzyme inhibitor-associated angioedema

Angioedema (AE) associated with angiotensin-converting enzyme inhibitors (ACEi) is a rare, but potentially life-threatening adverse reaction. Several studies have suggested that bradykinin (BK) is responsible for ACEi-induced AE, but the mechanism remains unclear. We investigated the metabolism of BK and des-Arg9-BK in the serum of 20 patients with a history of ACEi-associated AE and 21 control (C) subjects. Synthetic BK was incubated with the sera for various periods of time and residual BK and generated des-Arg9-BK were quantified by specific and sensitive enzyme immunoassays. No significant difference of half-life (t1/2) of both BK and des-Arg9-BK could be measured between C subjects and patients with AE (AE) in absence of ACEi. However, an analysis according to the prolonged (+) or not (-) t1/2 of des-Arg9-BK allowed a new stratification of C subjects and AE patients in four subgroups. The preincubation of sera with enalaprilat at a concentration inhibiting ACE significantly prevented the rapid degradation of BK and des-Arg9-BK in these four subgroups. In presence of ACEi, a subgroup (50%) of AE patients (AE + ) had a particularly significant rise of the t1/2 of des-Arg9-BK. Once ACE was inhibited, the concentration or the nature of the ACEi had no significant effect on the t1/2 of des-Arg9-BK. However, a test dilution of AE + sera with a control (C) serum showed that an enzyme defect rather than a circulating inhibitor could be responsible for the abnormal metabolism of des-Arg9-BK when ACE is inhibited. In conclusion, half of the patients with ACEi-associated AE present in serum had an enzyme defect involved in the des-Arg9-BK metabolism leading to its accumulation. The B1 agonist could be responsible, at least in part, for the local inflammatory reaction associated with the AE.

Contribution of angiotensin-converting enzyme to the cardiac metabolism of bradykinin: an interspecies study

The role of angiotensin-converting enzyme (ACE) in the metabolism of bradykinin (BK) has been studied in several tissues. However, and contrary to angiotensin I, the metabolism of BK at the cardiac level has not been investigated. In this study, we define the participation of ACE in the carboxy-terminal degradation of BK in heart membranes of the dog, human, rabbit, and rat. The calculation of the kinetic parameters characterizing the metabolism of BK and the generated des-Arg9-BK can be summarized as follows: the half-life (t1/2) of BK [dog (218 +/- 32 s) > human (143 +/- 9 s) = rat (150 +/- 4 s) > rabbit (22 +/- 2 s)] and of des-Arg9-BK [dog (1,042 +/- 40 s) > human (891 +/- 87 s) > rat (621 +/- 65 s) > rabbit (89 +/- 8 s)] both showed significant differences according to species. Enalaprilat, an ACE inhibitor, significantly prevented the rapid degradation of BK and des-Arg9-BK in all species studied, whereas retrothiorphan, a neutral endopeptidase inhibitor, and losartan, an angiotensin II type I receptor antagonist, did not affect this metabolism. The relative importance of ACE in the cardiac metabolism of BK was species related: dog (68.4 +/- 3.2%) = human (72.2 +/- 2.0%) > rabbit (47.7 +/- 5.0%) = rat (45.3 +/- 3.9%). ACE participation in the metabolism of des-Arg9-BK was as follows: rabbit (57.0 +/- 4.0%) > dog (39.9 +/- 8.8%) = human (25.4 +/- 5.5%) = rat (36.0 +/- 7.0%). The participation of cardiac kininase I (carboxypeptidase M) in the transformation of BK into des-Arg9-BK was minor: human (2.6 +/- 0.1%) > dog (0.9 +/- 0.1%) = rabbit (1.0 +/- 0.1%) = rat (1.0 +/- 0.1%). These results demonstrate that ACE is the major BK-degrading enzyme in cardiac membranes. However, the metabolism of exogenous BK by heart membranes is species dependent. Our observations could explain some discrepancies regarding the contribution of kinins in the cardioprotective effects of ACE inhibitors.

Serum interspecies differences in metabolic pathways of bradykinin and [des-Arg9]BK: influence of enalaprilat

Among the different enzymes responsible for the metabolism of bradykinin (BK), three peptidases look relevant in vivo: kininase I (KI), which transforms BK into its active metabolite, [des-Arg9]BK; kininase II (KII); and neutral endopeptidase, which inactivate BK and [des-Arg9]BK. The in vitro incubation of BK and [des-Arg9]BK in the serum of four species with or without enalaprilat and the quantification of the immunoreactivity of both peptides at different time intervals allowed the measurement of the kinetic parameters characterizing their metabolic pathways. Highly sensitive chemiluminescent enzyme immunoassays were used to measure the residual concentrations of BK and [des-Arg9]BK. Half-life (t1/2) of BK showed significant difference among species: rats (10 +/- 1 s) = dogs (13 +/- 1 s) < rabbits (31 +/- 1 s) < humans (49 +/- 2 s). t1/2 values of [des-Arg9]BK were also species dependent: rats (96 +/- 6 s) < < rabbits (314 +/- 6 s) = dogs (323 +/- 11 s) = humans (325 +/- 12 s). Enalaprilat significantly prevented the rapid BK and [des-Arg9]BK degradation in all species except that of [des-Arg9]BK in rat serum. Relative amount of BK hydrolyzed by serum KII was given as follows: rabbits (93.7 +/- 14.8%) = rats (83.6 +/- 6.7%) = humans (76.0 +/- 7.5%) > dogs (50.0 +/- 3.9%). Its importance in the hydrolysis of [des-Arg9]BK was 5.2 +/- 0.5% in rats < < 33.9 +/- 1.5% in humans < 52.0 +/- 1.1% in rabbits < 65.1 +/- 3.4% in dogs. The participation of serum KI in the transformation of BK into [des-Arg9]BK was dogs (67.2 +/- 5.3%) > > humans (3.4 +/- 1.2%) = rabbits (1.8 +/- 0.2%) = rats (1.4 +/- 0.3%). Finally, no significant difference on t1/2 values for BK and [des-Arg9]BK could be demonstrated between serum and plasma treated with either sodium citrate or a thrombin inhibitor. These results revealed striking species differences in the serum metabolism of kinins that could address at least partially some of the controversial data related to the cardioprotective role of kinins.

Detection of clenbuterol residues in hair

Sixty rats were grown in the presence of 10 (n = 30) and 100 (n = 30) micrograms kg-1 body mass of clenbuterol for a period of 10 d. An immunoextraction step coupled with a competitive enzyme immunoassay allowed the quantification of clenbuterol in hair upon 20 (10 micrograms kg-1) and 30 d (10 micrograms kg-1) after the last dose. This accumulation in hair contrasts with the rapid clearance in tissues. The nature of the immunoreactive material was confirmed by mass spectrometry.

Short-term response to dietary counseling of hyperlipidemic outpatients of a lipid clinic

OBJECTIVE

To evaluate the efficacy of a limited dietary intervention delivered by dietitians in a single counseling session on plasma lipid levels in free-living subjects with hyperlipidemia.

DESIGN

A 2-month, nonrandomized comparative study of dietary counseling efficacy in subjects with hyperlipidemia. Dietary instruction was conducted in a lipid clinic by dietitians. Subjects were instructed to follow a diet low in saturated fat and cholesterol (National Education Cholesterol Program step 1 or 2 diets) for 2 months with concomitant energy restriction for weight reduction when necessary. Another group of patients who did not receive dietary counseling during the same period served as a control.

SUBJECTS

Ambulatory patients were recruited from the Lipid Clinic of the Montreal Clinical Research Institute.

INTERVENTION

Dietary counseling was provided to 104 subjects with hypercholesterolemia and 113 subjects with hypertriglyceridemia. They were compared with 72 subjects with hypercholesterolemia and 80 subjects with hypertriglyceridemia who did not receive dietary counseling.

RESULTS

In the hypercholesterolemic group, significant reductions in plasma cholesterol (mean +/- standard deviation = -5.7 +/- 11.7%) and low-density lipoprotein cholesterol (LDL-C) (-7.3 +/- 14.2%) and no changes in plasma very-low-density lipoprotein cholesterol (VLDL-C) or high-density lipoprotein cholesterol (HDL-C) were observed after dietary counseling. The LDL-C response to diet was normally distributed, and 20% of the individuals with hypercholesterolemia reached LDL-C levels below 4.1 mmol/L. In patients with hypercholesterolemia and no clinical evidence of familial hypercholesterolemia, (n = 76) the reductions in plasma cholesterol (-6.6 +/- 10.8%) and LDL-C (-8.2 +/- 14%) were more pronounced. Among the latter patients, 27.6% reached LDL-C levels below 4.1 mmol/L. In subjects with hypertriglyceridemia, the reductions in plasma cholesterol (-4.8 +/- 12.8%), triglycerides (-20.7 +/- 33%), and VLDL-C (-19.5 +/- 29%) were associated with an increase in LDL-C (+8.5 +/- 25.7%) and HDL-C (+5.5 +/- 18%). Of the subjects with hypertriglyceridemia, 20% had triglyceride levels below 2.3 mmol/L after treatment. No significant changes were observed in the control groups during the same period.

CONCLUSIONS

Dietary counseling of subjects with hypercholesterolemia or hypertriglyceridemia was associated with beneficial changes in plasma lipid levels after 2 months of dietary intervention. However, longer and more controlled dietary interventions are necessary for most patients to achieve lipid goals.

Does pericardial drainage decrease the frequency of postpericardiotomy syndrome?

The postpericardiotomy syndrome occurs in 10% to 40% of patients who undergo open-heart surgery. Its frequency is reportedly decreased when pericardial drainage is used. To challenge this, 50 consecutive patients (1 was disqualified) were randomly assigned to two groups: one in which only the anterior mediastinum was drained (group 1) and the other in which the anterior mediastinum and posterior pericardium were drained (group 2). The surgical procedures performed were: coronary artery bypass grafting in 14 patients, valve surgery in 23 and repair of congenital defects in 12. The two groups were similar with respect to age and the volume of blood drained. Significant differences were found only for the duration of bypass and volume of blood given. At 7 to 10 days there were no differences in the frequency of fever, thoracic pain or presence of arthralgia. Findings were similar in both groups for leukocyte count, sedimentation rate, serum lactic dehydrogenase value and for the frequency of positive blood, urine and sputum cultures. Six patients (three in each group) had a postpericardiotomy syndrome that required steroid treatment and prolonged hospitalization for 10 more days. However, none had postpericardiotomy syndrome complicating coronary artery bypass surgery. None of the patients had cardiac tamponade. This study demonstrates that pericardial drainage has no effect on the frequency of postpericardiotomy syndrome and appears to be unnecessary after open-heart surgery.