Untargeted metabolomics analysis on kidney tissues from mice reveals potential hypoxia biomarkers

Chronic hypoxia may have a huge impact on the cardiovascular and renal systems. Advancements in microscopy, metabolomics, and bioinformatics provide opportunities to identify new biomarkers. In this study, we aimed at elucidating the metabolic alterations in kidney tissues induced by chronic hypoxia using untargeted metabolomic analyses. Reverse phase ultrahigh performance liquid chromatography-mass spectroscopy/mass spectroscopy (RP-UPLC-MS/MS) and hydrophilic interaction liquid chromatography (HILIC)-UPLC-MS/MS methods with positive and negative ion mode electrospray ionization were used for metabolic profiling. The metabolomic profiling revealed an increase in metabolites related to carnitine synthesis and purine metabolism. Additionally, there was a notable increase in bilirubin. Heme, N-acetyl-L-aspartic acid, thyroxine, and 3-beta-Hydroxy-5-cholestenoate were found to be significantly downregulated. 3-beta-Hydroxy-5-cholestenoate was downregulated more significantly in male than female kidneys. Trichome Staining also showed remarkable kidney fibrosis in mice subjected to chronic hypoxia. Our study offers potential intracellular metabolite signatures for hypoxic kidneys.

The metabolome of human milk is altered differentially by Holder pasteurization and high hydrostatic pressure processing

The milk metabolome is composed of hundreds of molecules that can impact infant development. In preterm infants, sterilized donor milk (DM) is frequently used for their feeding. We aimed to identify differences in the metabolome of DM after two types of milk sterilization: the Holder pasteurization (HoP) and a high hydrostatic pressure (HP) processing. DM samples were sterilized by HoP (62.5°C for 30 min) or processed by HP (350 MPa at 38°C). 595 milk metabolites were analyzed using an untargeted metabolomic analysis. Both treatments differentially altered several classes of compounds. The major changes noted included decreased levels of free fatty acids, phospholipid metabolites, and sphingomyelins. Decreases were more strongly noted in HP samples rather than in HoP ones. Both HoP and HP treatments increased the levels of ceramides and nucleotide compounds. The sterilization of human milk altered its metabolome especially for lipids.

Evaluating the strengths and challenges of PAX dream makers approach to mental health promotion: perspectives of youth and community members in indigenous communities in Manitoba, Canada

PAX Good Behaviour Game (PAX-GBG) is an evidence-based approach to co-create a nurturing environment where all children can thrive. This school-based approach was identified as a promising intervention for suicide prevention by First Nations communities in Manitoba, Canada. To enhance this mental health promotion approach, PAX Dream Makers was developed. It is a youth-led addition to PAX-GBG for middle and high school students. This study's aim was to examine, from the communities' perspectives, the influence of PAX Dream Makers on youth as well as its strengths, challenges and suggestions for future improvements. A case study method was conducted using interviews and focus groups with 30 youth and 17 adult mentors and elders. Participants reported that PAX Dream Makers provided support and encouragement to the youth, increased their resilience and provided an opportunity to be positive role models. It strengthened PAX-GBG implementation in schools. Challenges included: adult mentors availability, frequent teacher turn-over and community mental distress. Suggestions expressed were: being mindful of cultural and community contexts, increasing community leadership's understanding of PAX-GBG and better recruitment of mentors and youth. PAX Dream Makers approach was well-received by communities and holds great promise for promoting the well-being of First Nations youth.

Methamphetamine Use in Manitoba: An Evidence-to-Action (E2A) approach to a linked administrative data study

ObjectiveA multi-disciplinary E2A group was established as part of a linked administrative data study examining methamphetamine use in Manitoba. In this presentation we will share our experiences of establishing an E2A, embedding stakeholders in the research process, and outline an iterative engagement plan for the remaining study years. ApproachThe E2A group is led by two researchers with expertise in patient and public engagement and guided by Pal’s (2014) work on policy analysis and activation. Pal emphasizes a multidisciplinary and iterative process as the basis of a more inclusive approach to policy development for complex problems, such as the prevalence of methamphetamine use in Manitoba. Our goal in engaging public rightsholders, service providers and knowledge users in the research is to ensure that their first-hand knowledge and perspectives are reflected in the interpretations of the findings and that analyses address identified complexities in a culturally sensitive and equity-focused way. ResultsIn the fall of 2020 E2A members were recruited, including persons with lived experience using methamphetamines and their families/care-givers, academics, clinicians, government, and non-government stakeholders. Training was provided on the topics of trauma-informed care, public engagement, effects of colonial and racist institutions, and cultural safety. The first E2A meetings co-developed guiding principles, a vision and mission, as well as provided capacity building around administrative data research. This work was done as a foundation for the next two years, wherein the group will make decisions about key variables (ie: between methamphetamine use and mental health), interpretation of results, knowledge mobilization, and policy development using an iterative self-evaluation process. To date challenges addressed included public health restrictions related to Covid-19 and adapting the research flow to centre lived-experience decision making. ConclusionThe E2A group is a key component of this study and could serve as a model for other administrative data studies. The group prioritizes stakeholder knowledge, interprets results, flags potential biases in the data research process, and ensures the findings are relevant to the people they are meant to support.

Inulin Supplementation Mitigates Gut Dysbiosis and Brain Impairment Induced by Mild Traumatic Brain Injury during Chronic Phase

Mild traumatic brain injury (mTBI) has been shown to acutely alter the gut microbiome diversity and composition, known as dysbiosis, which can further exacerbate metabolic and vascular changes in the brain in both humans and rodents. However, it remains unknown how mTBI affects the gut microbiome in the chronic phase recovery (past one week post injury). It is also unknown if injury recovery can be improved by mitigating dysbiosis. The goal of the study is to fill the knowledge gap. First, we aim to understand how mTBI alters the gut microbiome through the chronic period of recovery (3 months post injury). In addition, as the gut microbiome can be modulated by diet, we also investigated if prebiotic inulin, a fermentable fiber that promotes growth of beneficial bacteria and metabolites, would mitigate dysbiosis, improve systemic metabolism, and protect brain structural and vascular integrity when administered after 3 months post closed head injury (CHI). We found that CHI given to male mice at 4 months of age induced gut dysbiosis which peaked at 1.5 months post injury, reduced cerebral blood flow (CBF) and altered brain white matter integrity. Interestingly, we also found that Sham mice had transient dysbiosis, which peaked 24 hours after injury and then normalized. After 8 weeks of inulin feeding, CHI mice had increased abundance of beneficial/anti-inflammatory bacteria, reduced abundance of pathogenic bacteria, enriched levels of short-chain fatty acids, and restored CBF in both hippocampi and left thalamus, compared to the CHI-control fed and Sham groups. Using machine learning, we further identified top bacterial species that separate Sham and CHI mice with and without the diet. Our results indicate that there is an injury- and time-dependent dysbiosis between CHI and Sham mice; inulin is effective to mitigate dysbiosis and improve brain injury recovery in the CHI mice. As there are currently no effective treatments for mTBI, the study may have profound implications for developing therapeutics or preventive interventions in the future.

Impact of acute lymphoblastic leukemia induction therapy: findings from metabolomics on non-fasted plasma samples from a biorepository

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is among the most common cancers in children. With improvements in combination chemotherapy regimens, the overall survival has increased to over 90%. However, the current challenge is to mitigate adverse events resulting from the complex therapy. Several chemotherapies intercept cancer metabolism, but little is known about their collective role in altering host metabolism.

OBJECTIVES

We profiled the metabolomic changes in plasma of ALL patients initial- and post- induction therapy.

METHODS

We exploited a biorepository of non-fasted plasma samples derived from the Dana Farber Cancer Institute ALL Consortium; these samples were obtained from 50 ALL patients initial- and post-induction therapy. Plasma metabolites and complex lipids were analyzed by high resolution tandem mass spectrometry and differential mobility tandem mass spectrometry. Data were analyzed using a covariate-adjusted regression model with multiplicity adjustment. Pathway enrichment analysis and co-expression network analysis were performed to identify unique clusters of molecules.

RESULTS

More than 1200 metabolites and complex lipids were identified in the total of global metabolomics and lipidomics platforms. Over 20% of those molecules were significantly altered. In the pathway enrichment analysis, lipids, particularly phosphatidylethanolamines (PEs), were identified. Network analysis indicated that the bioactive fatty acids, docosahexaenoic acid (DHA)-containing (22:6) triacylglycerols (TAGs), were decreased in the post-induction therapy.

CONCLUSION

Metabolomic profiling in ALL patients revealed a large number of alterations following induction chemotherapy. In particular, lipid metabolism was substantially altered. The changes in metabolites and complex lipids following induction therapy could provide insight into the adverse events experienced by ALL patients.

Overlap between child protection services and the youth justice system: protocol for a retrospective population-based cohort study using linked administrative data in Manitoba, Canada

INTRODUCTION

Children who have a history of involvement in child protection services (CPS) are over-represented in the youth and adult criminal justice systems. There are significant health and socioeconomic implications for individuals involved in either or both CPS and the justice system. Understanding the 'overlap' between these two systems would provide insight into the health and social needs of this population. This protocol describes a research programme on the relationship between the child welfare and the youth justice systems, looking specifically at the population involved in both CPS and the youth justice system. We will examine the characteristics associated with involvement in these systems, justice system trajectories of individuals with a history of CPS involvement and early adult outcomes of children involved in both systems.

METHODS AND ANALYSIS

Administrative data sets will be linked at the individual level for three cohorts born 1991, 1994 and 1998 in Manitoba, Canada. Involvement in CPS will be categorised as 'placed in out-of-home care', 'received in-home services, but was not placed in care' or 'no involvement'. Involvement in the youth justice system will be examined through contacts with police between ages 12 and 17 that either led to charges or did not proceed. Individual, maternal and neighbourhood characteristics will be examined to identify individuals at greatest risk of involvement in one or both systems.

ETHICS AND DISSEMINATION

The study was approved by the University of Manitoba Health Research Ethics Board and permission to access data sets has been granted by all data providers. We also received approval for the study from the First Nations Health and Social Secretariat of Manitoba's Health Information Research Governance Committee and the Manitoba Metis Federation. Strategies to disseminate study results will include engagement of stakeholders and policymakers through meetings and workshops, scientific publications and presentations, and social media.

A81 POST COLONOSCOPY COLORECTAL CANCERS IN MANITOBA: A POPULATION-BASED ANALYSIS

Background

Recent consensus guidelines from the World Endoscopy Organization (WEO) recommend all jurisdictions report unadjusted rates of post colonoscopy (PC) colorectal cancers (CRC). Until recently, prior reports have mostly focused on PC-CRC in the CRC screening age groups.

Aims

We evaluated the rate and predictors of PC-CRC in the adult population for the province of Manitoba from 1990 to 2016.

Methods

Individuals 18+ years at CRC diagnosis were identified from the Manitoba Cancer Registry. Colonoscopies in the 3 years preceding CRC diagnosis were identified via linkage to Manitoba Health (MH) physicians billing claims. CRCs were classified, based on WEO recommendations, as: (1) detected CRC (colonoscopy up to 6 months before CRC diagnosis) and (2) PC-CRC-3y (colonoscopy 6–36 months before CRC diagnosis). Generalized linear models with generalized estimating equations (to adjust for clustering within endoscopy physicians) were used to test for differences in rates over 3-time intervals (1990/91 – 1999/00; 2000/01 - 2009/10; 2010/11 – Dec 31 2016), provincial region of performance of colonoscopy and identify other associations from the MH data.

Results

Overall, 10.5% of the 16,639 CRCs diagnosed in the study period and with colonoscopy in the preceding 3 years were PC-CRC-3y. CRCs diagnosed between April 2000 and March 2010 were more likely to be PC-CRC-3y than those diagnosed between April 2010 and December 2016 (odds ratio [OR] 1.18; 95% confidence interval [CI]: 1.03–1.37). Female sex (OR for male: 0.86; 95% CI: 0.77–0.94), IBD diagnosis (OR 3.04; 95% CI: 2.56–4.52), prior CRC (OR 5.41; 95% CI: 4.61–6.34), prior colonoscopy (OR 2.10; 95% CI 1.88–2.36), diverticulosis (OR 2.39; 95% CI: 2.16–2.6), colonoscopy by GP (OR: 1.62; 95% CI 1.16–2.26 vs. surgeons) were associated with increased odds of PC-CRC-3y. There were no regional differences, and no effect of colonoscopy volume or age greater than 75 (or lower than 50).

Conclusions

In Manitoba, the PC-CRC-3y rate decreased slightly in recent years. The study results of large number of PC-CRC-3y along with only a slight decrease in rates over the years, support calls for root cause analysis to evaluate individual cases of PC-CRC. An initial focus could be the groups with increased risk of PC-CRC.

Funding Agencies

Manitoba Health

A24 RATE OF GASTROINTESTINAL ENDOSCOPY USE AND CONCOMITTANT ANESHESIOLOGY ASSISTANCE AND PREDICTORS OF ANESTHESIOLOGY ASSISTANCE: A POPULATION-BASED ANALYSIS

Background

There are limited Canadian data on time trends of gastrointestinal endoscopy (GIE) use and concomitant anesthesiology assistance.

Aims

To test the time trends and variations in concomitant anesthesiology assistance during GIE in the central Canadian province of Manitoba.

Methods

Physicians claims reimbursement data from the provincial health ministry were used to ascertain upper & lower GIE procedures and anesthesiology assistance annually from 1984 to 2016. The annual provincial population was determined from health insurance registration files. Generalized linear models with generalized estimating equations were used to test the linear trend over time and differences amongst age groups, health regions and income quintiles. Logistic regression analysis with generalized estimating equations was used to assess predictors of anesthesiology use.

Results

410, 685 individuals had at least one procedure in the observation period. Approximately half of the procedures were performed outside the recommended CRC screening age group of 50–74 years, with 38% among those less than 50 years. The average annual rate of increase was 4.6% (95% CI 4.4–4.8%). The rate of increase stabilized among the > 75 years group over the last 5 years of the study. There were marked regional variation in GIE procedures, with the smallest increase in Winnipeg region (the largest urban region):2.9% (95%CI: 2.5–3.3) vs. 5.2% (95%CI: 4.8–5.6) in Southern Health; RR: 2.2(figure 1 A). There were no differences in GIE rates by income quintile. Similar patterns were seen in analysis stratified by upper and lower GIE. Concomitant anesthesiology use ranged from 1% in Winnipeg region to 80% in the southern rural region (figure 1B). In the logistic regression analysis, independent predictors of concomitant anesthesiology use in rural regions included younger age, female sex, lower income quintile, and higher comorbidities of patients, GP endoscopist, region of physician practice, and lower volume endoscopy physician.

Conclusions

Marked regional variations in GIE use and concomitant anesthesiology use were observed in a universal health care system. Efforts to standardize care are needed to reduce variations.

Funding Agencies

Manitoba Health

Latent tuberculosis treatment completion rates from prescription drug administrative data

OBJECTIVE

In the province of Manitoba, Canada, given that latent tuberculosis infection (LTBI) treatment is provided at no cost to the patient, treatment completion rates should be optimal. The objective of this study was to estimate LTBI treatment completion using prescription drug administrative data and identify patient characteristics associated with completion.

METHODS

Prescription drug data (1999-2014) were used to identify individuals dispensed isoniazid (INH) or rifampin (RIF) monotherapy. Treatment completion was defined as being dispensed INH for ≥ 180 days (INH180) or ≥ 270 days (INH270) or RIF for ≥ 120 days (RIF120). Logistic regression models tested socio-demographic and comorbidity characteristics associated with treatment completion.

RESULTS

The study cohort comprised 4985 (90.4%) persons dispensed INH and 529 (9.6%) RIF. Overall treatment completion was 60.2% and improved from 43.1% in 1999-2003 to 67.3% in 2009-2014. INH180 showed the highest completion (63.8%) versus INH270 (40.4%) and RIF120 (27.0%). INH180 completion was higher among those aged 0-18 years (68.5%) compared with those aged 19+ (61.0%). Sex, geography, First Nations status, income quintile, and comorbidities were not associated with completion.

CONCLUSIONS

Benchmark 80% treatment completion rates were not achieved in Manitoba. Factors associated with non-completion were older age, INH270, and RIF120. Access to shorter LTBI treatments, such as rifapentine/INH, may improve treatment completion.

Comparative Metabolomic Sampling of Upper and Lower Airways by Four Different Methods to Identify Biochemicals That May Support Bacterial Growth

Bacteria need nutrients from the host environment to survive, yet we know little about which biochemicals are present in the airways (the metabolome), which of these biochemicals are essential for bacterial growth and how they change with airway disease. The aims of this pilot study were to develop and compare methodologies for sampling the upper and lower airway metabolomes and to identify biochemicals present in the airways that could potentially support bacterial growth. Eight healthy human volunteers were sampled by four methods: two standard approaches - nasal lavage and induced sputum, and two using a novel platform, synthetic adsorptive matrix (SAM) strips—nasosorption and bronchosorption. Collected samples were analyzed by Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS). Five hundred and eighty-one biochemicals were recovered from the airways belonging to a range of metabolomic super-pathways. We observed significant differences between the sampling approaches. Significantly more biochemicals were recovered when SAM strips were used, compared to standard sampling techniques. A range of biochemicals that could support bacterial growth were detected in the different samples. This work demonstrates for the first time that SAM strips are a highly effective method for sampling the airway metabolome. This work will assist further studies to understand how changes in the airway metabolome affect bacterial infection in patients with underlying airway disease.

Measuring social determinants of health and their impact on service use and medical complexity

IntroductionPopulation based data on the social determinants of health are not widely available, despite a wide body of evidence pointing to their importance. The Mantioba Population Research Data Repository offers a unique opportunity to leverage data from multiple government departments to assess the relationship between measurable social determinants and health. Objectives and ApproachUsing population based data from health, small area level census survey questions, social assisitance, education, social housing, child protective services and justice, linked at the individual level, we measured indicators of social complexity and mapped them in the province of Manitoba. Individuals with high level of social complexity were then compared with indicators of medical complexity and/or high use of medical services to determine the degree of overlap between these attributes of individuals. A matched group of individuals without any of the measured social complexities was developed and the number and reason for visits to primary care providers was compared. ResultsThe rate of individuals having three or more social complexities varied from a low of ~7% to a high of 35%, depending on the geographic location. High residential mobiity, involvement with the justice system and history of social assistance were the most frequent (>15%). Individuals with social complexities tended to be younger and live in poorer neighbourhoods than medically complex individuals or high users of health services. Socially complex persons had on average 5.5 primary care visits annually, compared to only ~3.5 for matched individuals with no social complexities. The overlap with high users of health services was slight (14.4%) and depended on the characteristics of the population. The overlap with medically complex patients ws higher (16.2%), particularly when medical complexity included mental health related diagnoses (20.4%). Conclusion/ImplicationsThe proportion of individuals with social complexities is large, and a substantial number have multiple risk factors. These individuals are for the most part a unique group, distinct from medically complex patients. Different strategies for care may be necessary to promote and sustain mental and physical health and wellbeing.

The Overlap Between the Child Welfare and Youth Justice Systems in Manitoba, Canada

IntroductionManitoba has one of the highest rates of children taken into care of child welfare services (Child and Family Services; CFS) in the world, and also one of the highest youth incarceration rates in Canada. Policy-makers recognize there is overlap between these systems; the extent of that overlap is unknown. Objectives and ApproachWe linked CFS, Justice, and Population Health Registry data to quantify the overlap between having a history of CFS during childhood (0-17 years) and being charged with a crime as a youth (12-17 years). Using a cohort approach, we selected all individuals in Manitoba who were born in 1988 (N=28,178); those not in the province at any time from 12-17 years were excluded, leaving a final cohort of 18,182. The cohort was divided into 3 groups according to CFS involvement: CFS out-of-home care (1,148); CFS in-home services (3,395); no CFS (13,639). Criminal charges between 12-17 years were identified. Results6.3% of our cohort had CFS out-of-home care, 18.7% received CFS in-home services, and 75% had no CFS involvement. 10.5% of the cohort were charged of a crime between 12-17 years. Almost half (46.6%) of youth who had CFS out-of-home care had criminal charges, compared to 19.4% of youth who had CFS in-home services, and 5.3% of youth with no CFS. Despite accounting for only 6.3% of the cohort, youth who had out-of-home care accounted for 28.0% of youth with criminal charges. Indigenous (First Nations (FN) and Metis) children/youth were over-represented in both systems; for example, 24.5% of FN youth had been in care compared to 3.1% of non-Indigenous; and 32.2% of FN youth were charged with a crime compared to 6.6% of non-Indigenous youth. Conclusion/ImplicationsThere is substantial overlap between the child welfare and youth justice systems, with overrepresentation of Indigenous youth in both systems. Culturally appropriate programs and policies aimed at supporting parents, families and communities to care for their own children will likely have long-term positive impacts on the youth justice system.

Association of the Social Determinants of Health With Quality of Primary Care

PURPOSE

In primary care, there is increasing recognition of the difficulty of treating patients' immediate health concerns when their overall well-being is shaped by underlying social determinants of health. We assessed the association of social complexity factors with the quality of care patients received in primary care settings.

METHODS

Eleven social complexity factors were defined using administrative data on poverty, mental health, newcomer status, and justice system involvement from the Manitoba Population Research Data Repository. We measured the distribution of these factors among primary care patients who made at least 3 visits during 2010-2013 to clinicians in Manitoba, Canada. Using generalized linear mixed modeling, we measured 26 primary care indicators to compare the quality of care received by patients with 0 to 5 or more social complexity factors.

RESULTS

Among 626,264 primary care patients, 54% were living with at least 1 social complexity factor, and 4% were living with 5 or more. Social complexity factors were strongly associated with poorer outcomes with respect to primary care indicators for prevention (eg, breast cancer screening; odds ratio [OR] = 0.77; 99% CI, 0.73-0.81), chronic disease management (eg, diabetes management; OR = 0.86; 99% CI, 0.79-0.92), geriatric care (eg, benzodiazepine prescriptions; OR = 1.63; 99% CI, 1.48-1.80), and use of health services (eg, ambulatory visits; OR = 1.09; 99% CI, 1.08-1.09).

CONCLUSIONS

Linking health and social data demonstrates how social determinants are associated with primary care service provision. Our findings provide insight into the social needs of primary care populations, and may support the development of focused interventions to address social complexity in primary care.

Metabolomic responses to lumacaftor/ivacaftor in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a life-limiting disease caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Lumacaftor/Ivacaftor is a novel CFTR modulator approved for patients that are homozygous for Phe508del CFTR, but its clinical effectiveness varies amongst patients, making it difficult to determine clinical responders. Therefore, identifying biochemical biomarkers associated with drug response are clinically important for follow-up studies.

METHODS

Serum metabolomics was performed on twenty patients with CF pre- and 6-month post-Lumacaftor/Ivacaftor response via Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS). Correlation with clinical variables was performed.

RESULTS

Metabolomics analysis demonstrated 188 differentially regulated metabolites between patients pre- and post-Lumacaftor/Ivacaftor initiation, with a predominance of lipid and amino acid alterations. The top 30 metabolites were able to differentiate pre- and post-Lumacaftor/Ivacaftor status in greater than 90% of patients via a random-forest confusion matrix. Alterations in bile acids, phospholipids, and bacteria-associated metabolites were the predominant changes associated with drug response. Importantly, changes in metabolic patterns were associated with clinical responders.

CONCLUSIONS

Selected key lipid and amino acid metabolic pathways were significantly affected by Lumacaftor/Ivacaftor initiation and similar pathways were affected in clinical responders. Targeted metabolomics may provide useful and relevant biomarkers of CFTR modulator responses.

Associations of cord blood metabolites with perinatal characteristics, newborn anthropometry, and cord blood hormones in project viva

CONTEXT

Metabolomics has emerged as a powerful tool to characterize biomarkers and elucidate physiological processes underlying adverse health outcomes. Little is known of these relationships during gestation and infancy, which are critical period for development of metabolic disease risk.

OBJECTIVES

To identify cord blood metabolite patterns associated with birth size; and to investigate relations of the birth size-associated metabolite patterns, and a branched chain amino acid (BCAA) metabolite pattern with a range of newborn and perinatal characteristics.

METHODS

Using untargeted mass-spectrometry, we quantified metabolites in cord blood of 126 mother-child pairs. After excluding 103 xenobiotics, we used principal components analysis (PCA) to consolidate the remaining 606 metabolites into principal components ("factors"). Next, we identified factors associated with gestational age-and sex-standardized birthweight z-score (BW/GA) and examined associations of the BW/GA-associated pattern(s) and the BCAA pattern with cord blood insulin, leptin, adiponectin, insulin-like growth factor (IGF)-1, IGF-2, and IGF binding protein 3 (IGFBP-3) using multivariable linear regression. Finally, we examined associations of maternal/perinatal characteristics with the cord blood metabolite patterns.

RESULTS

Mean BW/GA z-score was 0.27±0.98 units. About half of the infants were male (52.4%) and white (57.1%). Of the 6 factors identified from PCA, one was associated with higher BW/GA: Factor 5, which comprised metabolites involved in energy production (malate, succinate, fumarate) and nucleotide turnover (inosine 5-monophosphate, adenosine 5-monophosphate, cytidine 5-monophosphate) pathways. In multivariable analysis, Factor 5 was related to higher cord blood leptin (1.64 [95% CI: 0.42, 2.87] ng/mL) and IGF-1 even after adjusting for IGFBP-3 (3.35 [0.25, 6.44] ng/mL). The BCAA pattern was associated with higher BW/GA (0.20 [0.03, 0.36] z-scores) and IGFBP-3 (106.5 [44.7, 168.2] ng/mL). No maternal characteristics were associated with either metabolite pattern; however, infants born via Cesarean delivery exhibited a higher score for Factor 5, and gestation length was inversely associated with the BCAA pattern.

CONCLUSIONS

Metabolites in energy production and DNA/RNA turnover pathways in cord blood are associated with larger size at birth, and higher leptin and IGF-1. Similarly, the BCAA pattern was associated with larger birth size and IGFBP-3.

Greater occipital nerve blocks in chronic cluster headache: a prospective open-label study

BACKGROUND AND PURPOSE

Greater occipital nerve blockade (GONB) has been shown to be effective in episodic cluster headache. However, its use in chronic cluster headache (CCH) is less certain. The study aims to prospectively assess the efficacy and consistency of response to GONB in a large series of CCH patients.

METHODS

CCH patients who had a unilateral GONB and were referred to the National Hospital for Neurology and Neurosurgery were studied prospectively. Headache characteristics were collected using headache diaries. Responders were considered to be patients with a complete or partial response lasting at least 7 days. In a subgroup of responders the outcomes of serial GONB performed at 3-monthly intervals were also analysed.

RESULTS

Eighty-three CCH patients were studied. After the first GONB, a positive response was observed in 47 (57%) patients: 35 (42%) were rendered pain free, 12 (15%) had a partial benefit and one patient obtained <50% improvement. The duration of a positive response lasted a median of 21 days (range 7-504 days). There was a transient worsening of condition in 6% of patients. The overall rate and average duration of response remained consistent after the second [n = 37; 31 responders (84%); median duration 21 days], third [n = 28; 20 responders (71%); median duration 25 days] and fourth [n = 14; 10 responders (71%); median duration 23 days] injections.

CONCLUSION

GONB seems to be an efficacious treatment with reproducible effects in CCH patients. Performed three monthly, GONB may have a useful role in the management of CCH.

Dynamic two-axis curvature measurement using multicore fiber Bragg gratings interrogated by arrayed waveguide gratings

We describe the use of arrayed waveguide gratings (AWGs) in the interrogation of fiber Bragg gratings (FBGs) for dynamic strain measurement. The ratiometric AWG output was calibrated in a static deflection experiment over a +/-200 microepsilon range. Dynamic strain measurement was demonstrated with a FBG in a conventional single-mode fiber mounted on the surface of a vibrating cantilever and on a piezoelectric actuator, giving a resolution of 0.5 microepsilon at 2.4 kHz. We present results of this technique extended to measure the dynamic differential strain between two FBG pairs within a multicore fiber. An arbitrary cantilever oscillation of the multicore fiber was determined from curvature measurements in two orthogonal axes at 1125 Hz with a resolution of 0.05 m(-1).

Eicosanoid and muscarinic receptor blockade abolishes hyperventilation-induced bronchoconstriction

This study was designed to test the hypothesis that hyperventilation-induced bronchoconstriction (HIB) results from the combined effects of prostanoid and leukotriene metabolism. A bronchoscope was used in anesthetized dogs to record peripheral airway resistance and HIB before and after combined treatment with inhibitors of cyclooxygenase (indomethacin) and 5-lipoxygenase (MK-0591). Bronchoalveolar lavage fluid (BALF) cells and mediators from hyperventilated and control airways were also measured. Pretreatment with MK-0591 and indomethacin significantly attenuated, but did not abolish, HIB. However, addition of atropine nearly eliminated the residual response. Blockade of eicosanoid metabolism markedly reduced the concentrations of eicosanoids recovered in BALF after hyperventilation. Positive correlations between posthyperventilation BALF prostanoid and epithelial cell concentrations are suggestive of mucosal injury-induced mediator production and release. We conclude that HIB is prevented in the presence of eicosanoid and muscarinic-receptor blockade and that both classes of eicosanoids contribute similarly to the development of HIB.

Analysis of urine for drugs of abuse using mixed-mode solid-phase extraction and gas chromatography-mass spectrometry

A method for the simultaneous analysis of urine for the major drugs of abuse is described. The analytical procedure uses solid-phase extraction (SPE), gas chromatography-mass spectrometry (GC-MS) and a semi-automated identification process. It allows simultaneous extraction, derivatization and analysis of acidic, neutral and basic drugs from urine. Urine samples were subjected to enzymatic hydrolysis followed by SPE using Bakerbond narc-2 columns. The eluant was selectively derivatized with N-methyl-bis-trifluoroacetamide (MBTFA) and N-methyl-N-trimethylsilyltrifluoroacetamide + 1% trimethylchlorosilane. Analysis was performed using a GC-MS system operating in full scan mode. A simple macro programme was written to enhance the mass spectra identification capabilities of the MS software by producing extracted ion chromatograms (EIC) for the drugs of interest. Once a suspect compound was indicated by EIC, the mass spectrum of the compound was searched manually against reference libraries for positive identification and the retention time checked against that of the standard. This procedure has increased both the amount and the reliability of information given to clinicians without increasing the cost per sample. The system has been in routine operation for 24 months, processing up to 40 urine samples per day, with a usual turn-around time of 48 h.

Electrical burn of urethra as cause of stricture after transurethral resection

BACKGROUND AND PURPOSE

One of the most common complications of transurethral resection is urethral stricture. The exact etiology is still controversial. Postulated pathophysiology ranges from mechanical trauma to the urethra during the resection to inflammatory reaction secondary to local anesthesia. We propose electrical burn to the urethra as a contributory factor in some cases.

MATERIALS AND METHODS

Electrical events during transurethral resection were simulated in vitro. The distribution of current was measured at the loop/rollerball and in the outer metal sheath. Both an intact loop/rollerball and loop/rollerball with faulty insulation were tested. Various power outputs simulating coagulation, cutting, and vaporization were used. Data were recorded both in settings where the outer metal sheath was and was not smeared with nonconductive lubricating gel.

RESULTS

Approximately 20% of the total current output was shunted to the metal sheath when an intact loop/rollerball was used. One hundred percent of the current was short-circuited to the sheath when a loop/rollerball with faulty insulation was retracted into the sheath. Little current was detectable in the nonconductive lubricating gel. We then calculated the length of time required, in various settings, to reach tissue temperature of 45 degrees C, when protein denaturation starts. The higher the power output and the smaller the contacting surface area, the more likely it is for urethral burns to occur.

CONCLUSION

Our in vitro experiment showed that urethral burns secondary to stray current in the resectoscope sheath are unlikely when an intact loop is used. However, urethral burns can occur when a loop/rollerball with faulty insulation is used, especially in combination with nonconductive gel that is dispersed unevenly within the urethra.

Genital tract electrical burns during hysteroscopic endometrial ablation: report of 13 cases in the United States and Canada

We investigated 13 alleged thermal injuries to the genital tract of women undergoing hysteroscopic endometrial ablation. Possible mechanisms proposed to explain these injuries are hot-weighted speculum, povidone-iodine scrub solution, inadequate rinsing of Cidex sterilizing solution, and electrical burns. The history, nature, and distribution, as well as experimental evidence strongly support the hypothesis that these injuries are electrical due to capacitive coupled currents induced onto the sheath of the resectoscope, and/or stray currents generated by arcing or direct coupling from defective electrode insulation to the telescope, electrifying the entire resectoscope.

Intended and stray radiofrequency electrical currents during resectoscopic surgery

STUDY OBJECTIVE

To test the hypothesis that electrical burns of the genital tract and urethral strictures after hysteroscopic endometrial ablation and transurethral prostatectomy, respectively, are related to capacitive coupling and/or stray currents induced by intact and defective electrodes and/or resectoscopes.

DESIGN

Basic in vitro measurements.

SETTING

Laboratory.

MATERIALS

Porcine muscle and liver, resectoscope, electrosurgical unit (ESU), and ESU analyzer.

INTERVENTION

We measured electrical coagulation and cutting currents of rollerball and loop electrodes and the external sheath of the resectoscope from 80 to 200 W through a resistance load of 200 and 250 ohms, using intact electrodes and conditions simulating potential insulation defects along the shaft of the electrodes.

MEASUREMENTS AND MAIN RESULTS

Approximately 20% to 25% of current was induced by capacitive coupling to the resectoscope sheath. Touching porcine muscle or liver with small areas of the sheath while the generator was activated resulted in superficial tissue burn. Surrounding large segments of the sheath with tissue did not result in visible burns, indicating that under normal conditions the sheath acts as a dispersive electrode. Defective insulation of distal segments of the electrodes resulted in 100% transfer of current to the sheath and caused extensive electrical burns of tissue in contact with the sheath.

CONCLUSIONS

Capacitive coupled currents induced by intact resectoscopes and electrodes may cause thermal injury to surrounding tissue during prolonged resectoscopic surgery. Stray currents from defective insulation of the electrodes result in direct coupling of current to the telescope and sheath and cause extensive burns of surrounding tissues in contact with the sheath.

Mucosal injury and eicosanoid kinetics during hyperventilation-induced bronchoconstriction

Bronchoalveolar lavage (BAL) of canine peripheral airways was performed at various times after hyperventilation, and BAL fluid (BALF) cell and mediator data were used to evaluate two hypotheses: 1) hyperventilation-induced mucosal injury stimulates mediator production, and 2) mucosal damage is correlated with the magnitude of hyperventilation-induced bronchoconstriction. We found that epithelial cells increased in BALF immediately after a 2- and a 5-min dry air challenge (DAC). Prostaglandins D(2) and F(2alpha) and thromboxane B(2) were unchanged immediately after a 2-min DAC but were significantly increased after a 5-min DAC. Leukotriene C(4), D(4), and E(4) did not increase until 5 min after DAC. Hyperventilation with warm moist air did not alter BALF cells or mediators and caused less airway obstruction that occurred earlier than DAC. BALF epithelial cells were correlated with mediator release, and mediator release and epithelial cells were correlated with hyperventilation-induced bronchoconstriction. These observations are consistent with the hypothesis that hyperventilation-induced mucosal damage initiates peripheral airway constriction via the release of biochemical mediators.

Venous allografts prepared from stripped long saphenous vein. Is there a need for antibiotic sterilisation?

AIM

Can useful lengths of vein be retrieved from varicose vein stripping procedures; is it necessary to sterilise this tissue prior to use as vein allografts?

METHOD

Stripped long saphenous vein was retrieved at operation. Vein samples were cultured using direct plate inoculation and enrichment culture. Further samples were immersed in two low concentration antibiotic solutions and recultured. Smooth muscle viability was assessed after antibiotic immersion and storage by cryopreservation.

RESULTS

High quality vein could be retrieved by vein stripping. Vein segments grew skin commensals on enrichment culture despite negative cultures with standard media plate inoculation (Chi-squared = 53.34 1 d.f. p < 0.001). Low concentration antibiotic solutions sterilised processed vein. Smooth muscle cell viability was reduced by cryopreservation, Mann-Whitney p = 0.008 (control 98% S.E. 0.93 vs. cryopreserved 64% S.E. 6.58), but prior exposure to antibiotics did not compound this effect.

CONCLUSION

Useful lengths of vein grafts can be retrieved from varicose vein stripping procedures. Venous segments are frequently contaminated by skin commensals. Enrichment culture is required to detect contamination. Low concentration antibiotics sterilise venous-tissue without affecting smooth muscle cell viability.

ATP-dependent interaction of human mismatch repair proteins and dual role of PCNA in mismatch repair

DNA mismatch repair ensures genomic stability by correcting biosynthetic errors and by blocking homologous recombination. MutS-like and MutL-like proteins play important roles in these processes. In Escherichia coli and yeast these two types of proteins form a repair initiation complex that binds to mismatched DNA. However, whether human MutS and MutL homologs interact to form a complex has not been elucidated. Using immunoprecipitation and Western blot analysis we show here that human MSH2, MLH1, PMS2 and proliferating cell nuclear antigen (PCNA) can be co-immunoprecipitated, suggesting formation of a repair initiation complex among these proteins. Formation of the initiation complex is dependent on ATP hydrolysis and at least functional MSH2 and MLH1 proteins, because the complex could not be detected in tumor cells that produce truncated MLH1 or MSH2 protein. We also demonstrate that PCNA is required in human mismatch repair not only at the step of repair initiation, but also at the step of repair DNA re-synthesis.