Racial Differences in Donor-Derived Cell-Free DNA and Mitochondrial DNA After Heart Transplantation, on Behalf of the GRAfT Investigators

BACKGROUND

Black heart transplant patients are at higher risk of acute rejection (AR) and death than White patients. We hypothesized that this risk may be associated with higher levels of donor-derived cell-free DNA (dd-cfDNA) and cell-free mitochondrial DNA.

METHODS

The Genomic Research Alliance for Transplantation is a multicenter, prospective, longitudinal cohort study. Sequencing was used to quantitate dd-cfDNA and polymerase chain reaction to quantitate cell-free mitochondrial DNA in plasma. AR was defined as ≥2R cellular rejection or ≥1 antibody-mediated rejection. The primary composite outcome was AR, graft dysfunction (left ventricular ejection fraction <50% and decrease by ≥10%), or death.

RESULTS

We included 148 patients (65 Black patients and 83 White patients), median age was 56 years and 30% female sex. The incidence of AR was higher in Black patients compared with White patients (43% versus 19%; P=0.002). Antibody-mediated rejection occurred predominantly in Black patients with a prevalence of 20% versus 2% (P<0.001). After transplant, Black patients had higher levels of dd-cfDNA, 0.09% (interquartile range, 0.001-0.30) compared with White patients, 0.05% (interquartile range, 0.001-0.23; P=0.003). Beyond 6 months, Black patients showed a persistent rise in dd-cfDNA with higher levels compared with White patients. Cell-free mitochondrial DNA was higher in Black patients (185 788 copies/mL; interquartile range, 101 252-422 133) compared with White patients (133 841 copies/mL; interquartile range, 75 346-337 990; P<0.001). The primary composite outcome occurred in 43% and 55% of Black patients at 1 and 2 years, compared with 23% and 27% in White patients, P<0.001. In a multivariable model, Black patient race (hazard ratio, 2.61 [95% CI, 1.35-5.04]; P=0.004) and %dd-cfDNA (hazard ratio, 1.15 [95% CI, 1.03-1.28]; P=0.010) were associated with the primary composite outcome.

CONCLUSIONS

Elevated dd-cfDNA and cell-free mitochondrial DNA after heart transplant may mechanistically be implicated in the higher incidence of AR and worse clinical outcomes in Black transplant recipients.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02423070.

Pre-arrest doxycycline protects donation after circulatory death kidneys

Kidney injury during donation after circulatory determination of death (DCDD) includes warm ischemic (WI) injury from around the time of asystole, and cold ischemic (CI) injury during cold preservation. We have previously shown that Matrix Metalloproteinases (MMPs) are involved in CI injury and that Doxycycline (Doxy), an antibiotic and known MMP inhibitor, protects the transplant kidney during CI. The purpose of our study was to determine if Doxy given before asystole can also prevent injury during WI. A rat model of DCDD was used, including Control, Preemptive Doxy (45 mg/kg iv), and Preemptive and Perfusion (100 microM) Doxy groups. Thirty minutes after asystole, both kidneys were removed. The left kidney was perfused at 4 °C for 22 h, whereas the right was used to establish the degree of warm ischemic injury prior to cold preservation. MMP-2 in the perfusate was significantly reduced in both treatment groups [Control 43.7 ± 7.2 arbitrary units, versus Preemptive Doxy group 23.2 ± 5.5 (p = 0.03), and 'Preemptive and Perfusion' group 18.0 ± 5.6 (p = 0.02)]. Reductions in NGAL, LDH, and MMP-9 were also seen. Electron microscopy showed a marked reduction in mitochondrial injury scores in the treatment groups. Pre-arrest Doxy was associated with a reduction in injury markers and morphologic changes. Doxy may be a simple and safe means of protecting transplant kidneys from both WI and CI.

The prevalence of undiagnosed Prediabetes/type 2 diabetes, prehypertension/hypertension and obesity among ethnic groups of adolescents in Western Canada

Background

An increased incidence of type 2 diabetes in youth is occurring worldwide. While diverse ethnic groups are disproportionately affected by type 2 diabetes, studies that explore ethnic differences and undiagnosed prediabetes/type 2 diabetes in adolescents are scarce. This paper compares the prevalence of undiagnosed prediabetes and type 2 diabetes and the associated risk factors among various ethnic groups of adolescents living in Western Canada.

Methods

The data for this study were derived from two previous studies in which 396 adolescents, aged 14 to 19 years and living in a western Canadian province, were screened for undiagnosed prediabetes, diabetes, and any associated risk factors. Risk was determined by demographics, family history, anthropometric measurements (body mass index, BMI), blood pressure (BP), and HbA1c. Descriptive and inferential statistics (SPSS) were used to establish both risk and prevalence for prediabetes and type 2 diabetes. Chi-square analyses were done to determine if the risk factors occurred at higher frequencies in certain ethnicities.

Results

Based on BP, BMI, and HbA1c measurements, several statistically significant differences were identified in relation to ethnicity. Many of the adolescents had increased HbA1c levels, with 27.3% considered high risk and 2.3% in the prediabetes range; these high risk and prediabetes groups were heavily represented by Filipino (46%), Indigenous (22%), and European (10%) adolescents. Notable prevalence of prehypertension (17.7%) and hypertension (21.7%) were reported in European (59%) followed by Filipino (50%) and Indigenous (26%) adolescents. Higher numbers of adolescents in the European and Filipino ancestry groups had two or more risk factors (BP, BMI, & HbA1c) for developing type 2 diabetes in relation to the adolescents from the Indigenous group.

Conclusions

Ethnic adolescent groups demonstrate a notable prevalence of undiagnosed prediabetes and type 2 diabetes. Specifically, a significant number of Filipino adolescents had both increased HbA1c and blood pressure that has gone undetected. Earlier onset of type 2 diabetes is congruent with an increased risk of developing diabetes-associated complications and, ultimately, diabetes-related morbidity and mortality at a younger age. Future studies should explore how genetic and/or environmental factors among ethnic groups may contribute to early onset hypertension and prediabetes/type 2 diabetes.

Prediabetes: An emerging public health concern in adolescents

OBJECTIVES

To identify the presence of risk factors for type 2 diabetes (ethnicity, body mass index, blood glucose tolerance and blood pressure) and to determine the prevalence of prediabetes and type 2 diabetes in Canadian adolescents attending two multicultural urban high schools.

METHODS

A total of 266 multicultural urban high school students who live in a mid-sized Western Canadian city, aged 14-21, were screened for risk factors of prediabetes and type 2 diabetes in March-April 2018. Data with respect to demographics, family history of diabetes, anthropometrics, blood pressure and haemoglobin A1c (HbA1c) were collected. Data analysis was done using descriptive and inferential statistics in addition to chi-square analyses.

RESULTS

Based on body mass index, 38% of the adolescents were classified as either overweight or obese. Overweight rates for females (69.8%) were double than males (30.2%); however, males (52.2%) were more likely to obese than the females (47.8%). Based on HbA1c levels, 29.3% were at high risk to develop either diabetes or prediabetes and 2.6% were classified in the prediabetes range. Prehypertension/hypertension rates of 47% in the sample increased to 51% in those adolescents with elevated HbA1c; the majority of these prehypertensive/hypertensive participants were male.

CONCLUSION

High rates of overweight/obesity and prehypertension/hypertension were found in the adolescents studied and indicated the presence of prediabetes and an increased risk to develop type 2 diabetes and associated complications. Obesity and hypertension are major risk factors for developing type 2 diabetes, resulting in earlier exposure to metabolic consequences and, ultimately, long-term complications. Thus, timely research is needed to identify age-appropriate strategies that address risks and to develop recommendations for routine screening of adolescents for prediabetes.

Recombinant Factor VIII Measurement in a Hemophilia A Patient Undergoing Cardiopulmonary Bypass-Supported Cardiac Surgery

Patients with hemophilia A (Hem A) requiring cardiopulmonary bypass-supported cardiac surgery pose unique challenges for perioperative hemostatic management. This report describes a staged perioperative approach to clinical hematologic management as applied to an 80-year-old male of O-positive blood type with mild Hem A, who underwent successful, uncomplicated coronary artery bypass graft surgery. Hematologic management primarily consisted of normalization of plasma factor VIII levels followed by standard care. Conventional laboratory methods and point-of-care-testing methods such as thromboelastography and heparin management assays were combined to guide patient care. Minimal blood loss and minimal hemodilution techniques were also used to achieve favorable outcomes. The thorough preparation and execution of care by our multidisciplinary team from perfusion, pathology and laboratory medicine, cardiovascular surgery, transfusion services, nursing, and anesthesia, facilitated a safe, smooth, clinical course and an optimal outcome.

Performance Evaluation of the Plateletworks® in the Measurement of Blood Cell Counts as compared to the Beckman Coulter Unicel DXH 800

Prior to undergoing cardiac surgery many patients may have impaired platelet function due to platelet inhibition. Point of care testing (POCT) that produces quick results of platelet counts and function allow earlier clinician interpretation, diagnosis and treatment. Before being adopted for routine clinical use, a POCT device's performance must be evaluated by standard laboratory techniques to ensure high quality results. The purpose of this study is to determine the performance of the Plateletworks?V BC 3200 automated hematology analyzer by correlating its precision, accuracy and linearity for the measurement of blood counts to our hospital central laboratory analyzer (Beckman Coulter Unicel DXH 800). The study utilizes well described methods for Within-Run and Day-to-Day precision, comparison of methods (bias), and linearity. Control samples from the manufacturer were used for the precision studies, blood samples from 115 cardiac surgical subjects were used for comparison of methods and accuracy, and pre-diluted control samples from the manufacturer were used for the linearity studies. The precision of the Plateletworks® analyzer was acceptable. The overall coefficient of variation (CV) for the measured parameters at all levels of control for Within-Run precision was acceptable ranging from 0.65-6.4%. Likewise, the CV for the measured parameters at all levels of control for Day-to-Day precision was acceptable ranging from 1.45% to 6.7%. The correlation and accuracy between the two analyzers for the evaluated parameters (platelets, red blood cells, white blood cells, and hemoglobin) was acceptable. The linearity for the measured parameters was also acceptable with a range between 98-100%. The performance of the Plateletworks® analyzer was acceptable for providing blood cell counts as compared to our central hospital laboratory analyzer.

Bivalirudin as an adjunctive anticoagulant to heparin in the treatment of heparin resistance during cardiopulmonary bypass-assisted cardiac surgery

Heparin resistance (unresponsiveness to heparin) is characterized by the inability to reach acceptable activated clotting time values following a calculated dose of heparin. Up to 20% of the patients undergoing cardiothoracic surgery with cardiopulmonary bypass using unfractionated heparin (UFH) for anticoagulation experience heparin resistance. Although UFH has been the "gold standard" for anticoagulation, it is not without its limitations. It is contraindicated in patients with confirmed heparin-induced thrombocytopenia (HIT) and heparin or protamine allergy. The safety and efficacy of the use of the direct thrombin inhibitor bivalirudin for anticoagulation during cardiac surgery has been reported. However, there have been no reports on the treatment of heparin resistance with bivalirudin during CPB. In this review, we report the favorable outcome of our single-center experience with the alternative use of bivalirudin in the management of anticoagulation of heparin unresponsive patients undergoing coronary artery bypass graft surgery.

Outcomes comparison of 5 coated cardiopulmonary bypass circuits versus an uncoated control group of patients undergoing cardiac surgery

Attenuated inflammatory response and decreased platelet activation have been claimed repeatedly when biocompatible circuits are used for cardiopulmonary bypass. We evaluated five Health Canada approved biocompatible circuit coatings (BCC) against an un-coated control group to determine their effectiveness in improving post-operative outcomes.

Patients were assigned to the Control group or one of the 5 coated circuit groups: 40 Control; 33 Trillium; 32 Phisio; 34 Bioline; 33 X; and 11 GBS. Measured outcomes included: ventilator time; ICU time; post-operative chest tube drainage and transfusion volume; high sensitivity C-reactive protein (hsCRP); tau protein; and pre- and 72-hour post-operative anti-saccadic eye movement test comparisons.

Results: 183 patients were enlisted into the study. One arm of the study (GBS) was abandoned after 11 patients on account of inconsistent pressure excursions within the oxygenator and the excessive consumption of platelets necessitating transfusion. Patients in the X-coated group had significantly longer ventilator and intensive care unit (ICU) time compared to the three remaining coated circuit study groups. Though not significant, patients in the X group also demonstrated the highest post-operative chest tube losses, the most platelet transfusions, the highest tau protein levels and the lowest post-operative anti-saccadic eye movement test (ASEMT) results compared to the three remaining coated groups. The patients in the Trillium, Bioline and Phisio groups showed an improvement in ventilator and ICU time relative to the Control group. The diabetic patients in the Trillium, Bioline and Phisio groups showed an improvement in bleeding relative to the diabetic patients in the Control group.

Conclusion: We compared all 5 coated circuits approved for clinical use in Canada against an uncoated control circuit. Three of the 5 coated circuits (Trillium, Phisio and Bioline BCC) were found to improve ventilator and ICU time compared to Control. Further studies are indicated to validate these results and their impact upon approval criteria, purchasing choices and safe clinical practice, especially as applied to higher risk diabetic patients.

A comparison of intra-operative cell-saving strategies upon immediate post-operative outcomes after CPB-assisted cardiac procedures

Cardiotomy suction has been associated with adverse outcomes under routine conditions in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). We hypothesized that the routine use of a cell saver (CS) in place of the cardiotomy sucker would have no negative impact on transfusion rate (TR), chest tube drainage (CTD), ventilation time (VT) or intensive care unit length of stay (ICULOS) while avoiding the detrimental effects of cardiotomy suction. Retrospective data were collected from 69 patients where a cell saver was not used (NCS). Prospective data were collected from 219 patients who were followed after the implementation of an intra-operative cell saver. No significant increase in transfusion rate, chest tube drainage or ventilation time was found between the NCS group and the CS group. However, post-operative hemoglobin concentrations were significantly higher in the CS group (0.0001) and the CS group spent significantly less time in the ICU (p=0.018).

The homeless experience: clinic building in a community health discovery-learning project

The concept of discovery learning is exemplified in this account of four students and their instructor who began and developed a nurse-run clinic for the homeless in a community health project. The students were registered nurses returning for their bachelor's degrees. They experienced frustration at learning the difference between care based on their assessments of patients' needs and care geared to clients' assessments of desired interventions. The journals that they kept reveal self-discovery as well as new respect for other humans. In addition, a new type of community care emerged, which gives all indications of surviving.

Effect of sex and castration on nicotine-induced activity responses

The nature of the short-term interactions between nicotine and sex hormones in affecting activity remain unclear. The present study was an investigation of these effects. Three levels of nicotine injection--0.0 (saline control), 0.2 mg/kg body weight, and 0.4 mg/kg body weight-were given to male, female, and castrated Sprague-Dawley albino rats. Activity was measured when the animals were 6 weeks and 12 weeks old. Nicotine produced an initial depression of activity relative to the saline control levels, and a later activation which peaked at 40 to 60 minutes. The biphasic effect was most striking in female animals, but the forms of the curves relating activity to time in all groups were quite similar.

Effects of nicotine on weight change and food consumption in rats

The present study was designed to test the effects of nicotine and nicotine withdrawal on weight change and food consumption in rats. Twelve male and 12 female three month old Sprague-Dawley rats were divided into three treatment groups: 0.2, 0.4, and 0.6 mg nicotine/kg body wt. Half were given subcutaneous nicotine treatment for three weeks and then saline for three weeks; treatment sequence was reversed for the other half. Injections were administered three times daily throughout the experimental period. Prior to treatment, baseline measures were established for both food consumption and weight. Mean differences in weight change were calculated on a weekly basis throughout the experiment. Overall tests indicated that nicotine withdrawal produced significant (p less than 0.05) weight gains and nicotine administration produced inhibition of weight gain. A significant sex X drug X time interaction (p less than 0.05) demonstrated that food consumption increased when nicotine was discontinued and decreased when nicotine was administered. Specific comparison tests showed these effects on food consumption and weight were strongest at the 0.6 level and that larger effects were obtained for males than for females.

Effects of nicotine on two types of motor activity in rats

Effects of injections of two doses of nicotine (o.2 and 0.4 mg/kg body wt) were tested on general activity (in a photocell chamber) and on locomotor activity (in an activity wheel) in male and female rats of two ages (40 and 90 days). Behavior was monitored under light and dark conditions at 15, 30, and 45 min post-injection over a period of 12 days. A general excitatory effect of nicotine was observed in the photocell chamber, with the high dosage greatly increasing activity for younger and female animals. In the activity wheel an initial depressant effect was observed followed by excitation at the lower dose. no evidence for tolerance or difference between light and dark test conditions was found.