Glycine, a Dispensable Amino Acid, Is Conditionally Indispensable in Late Stages of Human Pregnancy

BACKGROUND

Recently, we showed that there are higher protein, lysine, and phenylalanine requirements in late stages of pregnancy compared with early stages. Animal studies have suggested an increased dietary need for specific dispensable amino acids in pregnancy; whether such a need exists in human pregnancies is unknown.

OBJECTIVE

The objective of the current study was to examine whether healthy pregnant women at midgestation (20-29 wk) and late gestation (30-40 wk) have a dietary demand for glycine, a dispensable amino acid, using the indicator amino acid oxidation method and measurement of plasma 5-oxoproline concentrations.

METHODS

Seventeen healthy women (aged 26-36 y) randomly received different test glycine intakes (range: 5-100 mg·kg-1·d-1) during each study day in midgestation (∼26 wk, n = 17 observations in 9 women) and late gestation (∼35 wk, n = 19 observations in 8 women). Diets were isocaloric with energy at 1.7 × resting energy expenditure. Protein was given as a crystalline amino acid mixture based on egg protein composition at current estimated average requirement (EAR; 0.88 g·kg-1·d-1). Breath samples were collected at baseline and isotopic steady state to measure oxidation of L-[1-13C]phenylalanine to 13CO2 (F13CO2). Plasma was collected at the sixth hour of the study day. Linear regression crossover analysis and simple linear regression were used to assess responses in F13CO2 and plasma 5-oxoproline concentrations to different glycine intakes.

RESULTS

No statistically significant responses were observed in midgestation. However, in late gestation, lower glycine intakes resulted in higher rates of F13CO2 (suggesting low protein synthesis) with a breakpoint for phenylalanine oxidation at >37 mg glycine·kg-1·d-1 and higher plasma 5-oxoproline (suggesting low glycine availability) with a breakpoint >27 mg glycine·kg-1·d-1.

CONCLUSIONS

The findings suggest that glycine should be considered a "conditionally" indispensable amino acid during late gestation, especially when protein intakes are at 0.88 g·kg-1·d-1, the current EAR. This trial was registered at clinicaltrials.gov as NCT02149953.

Cardiovascular Functional Changes in Chronic Kidney Disease: Integrative Physiology, Pathophysiology and Applications of Cardiopulmonary Exercise Testing

The development of cardiovascular disease during renal impairment involves striking multi-tiered, multi-dimensional complex alterations encompassing the entire oxygen transport system. Complex interactions between target organ systems involving alterations of the heart, vascular, musculoskeletal and respiratory systems occur in Chronic Kidney Disease (CKD) and collectively contribute to impairment of cardiovascular function. These systemic changes have challenged our diagnostic and therapeutic efforts, particularly given that imaging cardiac structure at rest, rather than ascertainment under the stress of exercise, may not accurately reflect the risk of premature death in CKD. The multi-systemic nature of cardiovascular disease in CKD patients provides strong rationale for an integrated approach to the assessment of cardiovascular alterations in this population. State-of-the-art cardiopulmonary exercise testing (CPET) is a powerful, dynamic technology that enables the global assessment of cardiovascular functional alterations and reflects the integrative exercise response and complex machinery that form the oxygen transport system. CPET provides a wealth of data from a single assessment with mechanistic, physiological and prognostic utility. It is an underutilized technology in the care of patients with kidney disease with the potential to help advance the field of cardio-nephrology. This article reviews the integrative physiology and pathophysiology of cardio-renal impairment, critical new insights derived from CPET technology, and contemporary evidence for potential applications of CPET technology in patients with kidney disease.

Characteristics and outcome of patients with relapsed/refractory Hodgkin lymphoma following front-line escalated BEACOPP-based chemotherapy: a report from the Australasian Lymphoma Alliance

The optimal management of the small number of patients who experience early failure of eBEACOPP in Hodgkin lymphoma (HL) is unclear. We identified 12 patients with HL who progressed within 12 months of the front-line therapy between January 2010 and July 2019. Median time of first progression following diagnosis was 7 months (range 2.1-13.2). Nine patients proceeded to stem cell therapy following salvage therapy (8 autografts, 1 allograft). Seven patients received novel therapy after relapse, of these, 6 were alive at census, versus 2 out of 5 of those who had standard therapy alone. At the end of follow up (median 22 months), 4 were deceased from progressive disease, 6 were in complete remission and 2 in partial remission on continuing therapy. The outcome of patients with primary refractory HL to eBEACOPP therapy is better than expected and the use of a novel agents after relapse may be a contributing factor.

Klotho and the Treatment of Human Malignancies

Klotho was first discovered as an anti-ageing protein linked to a number of age-related disease processes, including cardiovascular, renal, musculoskeletal, and neurodegenerative conditions. Emerging research has also demonstrated a potential therapeutic role for Klotho in cancer biology, which is perhaps unsurprising given that cancer and ageing share similar molecular hallmarks. In addition to functioning as a tumour suppressor in numerous solid tumours and haematological malignancies, Klotho represents a candidate therapeutic target for patients with these diseases, the majority of whom have limited treatment options. Here, we examine contemporary evidence evaluating the anti-neoplastic effects of Klotho and describe the modulation of downstream oncogenic signalling pathways, including Wnt/β-catenin, FGF, IGF1, PIK3K/AKT, TGFβ, and the Unfolded Protein Response. We also discuss possible approaches to developing therapeutic Klotho and consider technological advances that may facilitate the delivery of Klotho through gene therapy.

FUS-mediated dysregulation of Sema5a, an autism-related gene, in FUS mice with hippocampus-dependent cognitive deficits

Pathological fused in sarcoma (FUS) inclusions are found in 10% of patients with frontotemporal dementia and those with amyotrophic lateral sclerosis (ALS) carrying FUS mutations. Current work indicates that FUS mutations may incur gain-of-toxic functions to drive ALS pathogenesis. However, how FUS dysfunction may affect cognition remains elusive. Using a mouse model expressing wild-type human FUS mimicking the endogenous expression pattern and level within the central nervous system, we found that they developed hippocampus-mediated cognitive deficits accompanied by an age-dependent reduction in spine density and long-term potentiation in their hippocampus. However, there were no apparent FUS aggregates, nuclear envelope defects and cytosolic FUS accumulation. These suggest that these proposed pathogenic mechanisms may not be the underlying causes for the observed cognitive deficits. Unbiased transcriptomic analysis identified expression changes in a small set of genes with preferential expression in the neurons and oligodendrocyte lineage cells. Of these, we focused on Sema5a, a gene involved in axon guidance, spine dynamics, Parkinson's disease and autism spectrum disorders. Critically, FUS binds directly to Sema5a mRNA and regulates Sema5a expression in a FUS-dose-dependent manner. Taken together, our data suggest that FUS-driven Sema5a deregulation may underlie the cognitive deficits in FUS transgenic mice.

AB1126 THE RELIABILITY AND DIAGNOSTIC ACCURACY OF DIGITAL TOMOSYNTHESIS COMPARED WITH CONVENTIONAL RADIOGRAPHY FOR THE INVESTIGATION OF SACROILIITIS

Background:

Conventional radiography remains part of the diagnosis of axial spondyloarthritis and determines qualification for biologic disease modifying anti-rheumatic drugs in many countries. The standard anteroposterior radiograph (XR) incompletely images the complex sacroiliac joint with recognised unacceptably low levels of agreement between readers. Digital tomosynthesis (DTS) uses conventional radiographic projections to create a three-dimensional image and is a potential alternative for the initial radiographic detection and grading of sacroiliitis.

Objectives:

To compare the level of agreement between two radiologists when reporting sacroiliac joint imaging with digital tomosynthesis versus conventional radiography, as well as to compare the diagnostic accuracy of each imaging modality.

Methods:

229 consecutive patients that had radiography and digital tomosynthesis performed at Footscray Hospital, Melbourne, Australia were included. Two blinded radiologists independently re-reported all images according to the modified New York criteria, or listed an alternative diagnosis. An overall assessment of each image as inflammatory sacroiliitis, normal or non-inflammatory disease was also recorded. Demographic and clinical data were extracted from medical records. Agreement between and within readers was evaluated using kappa (κ) statistic. Diagnostic accuracy was calculated by comparing each reader’s overall assessment against 2 reference standard comparators: most recent rheumatologist diagnosis and fulfillment of ASAS criteria at any time point.

Results:

The intra-reader agreement of reader 1 was almost perfect for the left, right and overall sacroiliac joint assessments (κ 0.77 - 0.94), with DTS outperforming XR. Reader 2 agreement was mostly moderate (κ 0.39 - 0.69), with DTS and XR better on the left and right sacroiliac joint respectively, but XR having better overall assessment. The inter-reader agreement of DTS for all patients was moderate and better than XR as shown in the Table. When excluding non-spondyloarthritis patients, inter-reader agreement improved (κ 0.50 to 0.58) but there was no significant difference between DTS and XR. Using reader 1, the sensitivity of DTS (64.8 - 66.7%) was better than XR (54.9 - 60.7%) but low, in keeping with what is known about radiographic sacroiliitis and axial spondyloarthritis. The specificity of XR (78.5 – 80.3%) was better than DTS (72.3 – 73.1%). There were no significant differences when fulfillment of modified New York Criteria was used as a reader’s positive test.

Table.

Inter-rater reliability between the readers

All patients(N=229)*Inflammatory sacroiliitis & normal patients (N=164)**Inflammatory sacroiliitis patients (N=92)**XR Right0.360.520.56DTS Right0.390.500.51XR Left0.340.550.56DTS Left0.420.550.58XR Overall0.40DTS Overall0.45

*Non-weighted kappa statistic

**Weighted kappa statistic

Conclusion:

DTS demonstrated moderate reliability for assessment of sacroiliitis, marginally better than conventional radiography. Overall levels of agreement for both imaging modalities were however lower than radiography in previous studies, with several possible contributing factors. A prospective study in a selected spondyloarthritis cohort may better determine any benefit of DTS.

References:

[1]Christiansen AA, Hendricks O, Kuettel D, Horslev-Petersen K, Jurik AG, Nielsen S, et al. Limited Reliability of Radiographic Assessment of Sacroiliac Joints in Patients with Suspected Early Spondyloarthritis. The Journal of rheumatology. 2017;44(1):70-7.

[2]van Tubergen A, Heuft-Dorenbosch L, Schulpen G, Landewe R, Wijers R, van der Heijde D, et al. Radiographic assessment of sacroiliitis by radiologists and rheumatologists: does training improve quality? Annals of the rheumatic diseases. 2003;62(6):519-25.

Disclosure of Interests:

None declared

Dietary Phenylalanine and Tyrosine Requirements in Healthy Human Pregnancy

Objectives

Phenylalanine (PHE), an indispensable amino acid, is required for protein synthesis and is fundamental for proper fetal development. PHE is the precursor for tyrosine (TYR), a conditionally indispensable amino acid that is crucial for synthesis of dopamine, norepinephrine and epinephrine. The current recommendation for PHE + TYR during pregnancy is 36 mg/kg/d, which is factorially determined and not based on experimental studies. Our objective was to experimentally determine PHE + TYR requirements during early (13–19 wks) and late (33–39 wks) gestation, accounting for potential changes in requirement since metabolism and rate of growth are not static throughout pregnancy.

Methods

20 women (22–39 y) were studied using the non-invasive stable isotope based indicator amino acid oxidation technique (with L-[1–,13C]Leucine as indicator) for a total of 51 study days. A range of PHE intakes (5 to 100 mg/kg/d) were provided in early and late pregnancy as isonitrogenous and isocaloric meals on separate study days, in the absence of dietary tyrosine. Breath samples were collected at baseline and isotopic steady state. Samples were analyzed for ,13C enrichment on an Isotope Ratio Mass Spectrometer, and the PHE + TYR requirement was determined using two-phase linear regression crossover analysis to identify a breakpoint in ,13CO2 production (represents the minimum dietary requirement) in response to changes in PHE intake.

Results

Results suggest the PHE + TYR requirement is 43 and 55 mg/kg/d in early and late pregnancy respectively.

Conclusions

Our preliminary results suggest that PHE + TYR requirements in pregnancy are higher compared to current recommendations, and are different between gestational stages. These results are similar to our previous findings of increased requirements for dietary protein, lysine and PHE (in the presence of excess TYR) in late compared to early pregnancy. They also highlight the need to investigate the dietary requirement of the remaining indispensable amino acids during this life stage.

Funding Sources

Canadian Institute of Health Research.

Complication rates and lymph node count between two different skin incisions at time of inguino-femoral lymph node dissection in vulvar cancer

Introduction

Inguino-femoral lymph node dissection plays a crucial role in the management of vulvar cancer. The procedure is associated with high complication rates, including infection, lymphocysts/lymphoedema and wound dehiscence. Several skin incision techniques exist and practice among gynecology oncologists is variable. Little evidence exists to guide surgeons regarding the optimal surgical approach. This study aimed to determine the difference in 30-day complication rates, number of lymph nodes and length of stay between patients undergoing the modified oblique and classical ‘lazy S’ skin incision.

Methods

A retrospective review between January 2014 and September 2018 was performed in the University Hospital of Wales, Cardiff. All cases of inguino-femoral lymph node dissection performed for vulvar cancer were included in the study without exclusion. Data collected included age, body mass index (BMI), incision type, suture material, length of hospital stay, complication rates, cancer stage, lymph node count, lymph node positivity rate and recurrence rates. Data were analyzed using SPSS software and clinical significance was set as p<0.05.

Results

Thirty-five cases of classical ‘lazy S’ and 14 cases of modified oblique were included in the analysis. The mean patient age was 65 years (range 41–86) in the classical ‘lazy S’ group and 58 years (range 19–81) in the modified oblique group. The mean BMI was 28 kg/m2 (range 18–45) in the classical ‘lazy S’ group and 29 kg/m2 (range 20–36) in the modified oblique group. In the classical ‘lazy S’ group, the stage classification was as follows: stage IB (18), II (2), IIIA (3), IIIB (4), IIIC (8). In the modified oblique group, the stage classification was: stage IB (8), II (4), IIIA (2). Grade 3–4 complications were statistically significantly more common after the classical ‘lazy S’ versus the modified oblique operation (20/35, 57.1% vs 2/14, 14.3%, p<0.02). Mean number of nodes harvested was statistically significantly higher in the classical ‘lazy S’ group compared with the modified oblique group (11.1 nodes, range 6–17 vs 7 nodes, range 4–11, p<0.001). Node positivity rate was higher in the classical ‘lazy S’ group compared with the modified oblique group (28.6% vs 10%, p=0.08). Mean hospital stay was statistically significantly longer in patients undergoing classical ‘lazy S’ versus modified oblique (10.7 vs 4.5 days, p=0.02). One case of groin node recurrence occurred and this patient was in the classical ‘lazy S’ arm.

Conclusion

The rate of overall and serious complications was lower after modified oblique skin incision compared with classical ‘lazy S’. However, the absolute lymph node count and lymph node positivity rate were higher in the ‘lazy S’ group.

Cuffless Single-Site Photoplethysmography for Blood Pressure Monitoring

One in three adults worldwide has hypertension, which is associated with significant morbidity and mortality. Consequently, there is a global demand for continuous and non-invasive blood pressure (BP) measurements that are convenient, easy to use, and more accurate than the currently available methods for detecting hypertension. This could easily be achieved through the integration of single-site photoplethysmography (PPG) readings into wearable devices, although improved reliability and an understanding of BP estimation accuracy are essential. This review paper focuses on understanding the features of PPG associated with BP and examines the development of this technology over the 2010-2019 period in terms of validation, sample size, diversity of subjects, and datasets used. Challenges and opportunities to move single-site PPG forward are also discussed.

Acceptability and appropriateness of a perinatal depression preventive group intervention: a qualitative analysis

BACKGROUND

Perinatal depression is a prevalent public health concern. Although preventive interventions exist, there is limited literature on the acceptability and appropriateness of these interventions, especially those delivered by paraprofessionals. The Mothers and Babies Program (MB) is a group-based perinatal depression preventive intervention delivered prenatally. A cluster-randomized controlled trial examined the acceptability, appropriateness, and effectiveness of MB delivered by mental health professionals compared to paraprofessional staff from home visiting programs.

METHODS

The full study enrolled 874 pregnant women. Fifty-three facilitators were trained and delivered the MB intervention to women in one of seven states in the United States. Semi-structured interviews were attempted with a randomly-selected subset of the full sample of pregnant women who received the MB intervention and with all facilitators. Specifically, interviews were conducted with 88 women who received the MB group intervention (45 in the paraprofessional-led arm and 43 in the mental health professional-led arm) and 46 women who facilitated the groups (27 home visiting staff and 19 mental health professionals). Interviews were conducted over the phone in English or Spanish and audio recorded. The recordings were translated into English, as needed, and transcribed. Thematic analysis was conducted using NVIVO to identify key themes related to intervention acceptability and appropriateness. Similarities and differences between study arms were explored.

RESULTS

Clients and facilitators found the MB content and group format acceptable. Challenges included maintaining group attendance, transportation issues, and managing group discussion. Overall, facilitators found the intervention appropriate for pregnant clients with some challenges presented for clients in crisis situations, experiencing housing instability, and with literacy and learning challenges. Participants provided suggestions for improvement, both for the course content and implementation. There were no significant differences found between study arms.

CONCLUSIONS

Overall, clients and facilitators enjoyed MB irrespective of study arm, and facilitators found the intervention appropriate for the population. These findings add to the qualitative literature on perinatal depression preventive interventions, specifically those delivered by paraprofessionals.

TRIAL REGISTRATION

This trial is registered on ClinicalTrials.gov (Initial post: December 1, 2016; identifier: NCT02979444).

miR-218 Expressed in Endothelial Progenitor Cells Contributes to the Development and Repair of the Kidney Microvasculature

Ischemia due to hypoperfusion is one of the most common forms of acute kidney injury. We hypothesized that kidney hypoxia initiates the up-regulation of miR-218 expression in endothelial progenitor cells (EPCs) to guide endocapillary repair. Murine renal artery-derived EPCs (CD34+/CD105-) showed down-regulation of mmu-Mir218-5p/U6 RNA ratio after ischemic injury, while in human renal arteries, MIR218-5p expression was up-regulated after ischemic injury. MIR218 expression was clarified in cell culture experiments in which increases in both SLIT3 and MIR218-2-5p expressions were observed after 5 minutes of hypoxia. ROBO1 transcript, a downstream target of MIR218-2-5p, showed inverse expression to MIR218-2-5p. EPCs transfected with a MIR218-5p inhibitor in three-dimensional normoxic culture showed premature capillary formation. Organized progenitor cell movement was reconstituted when cells were co-transfected with Dicer siRNA and low-dose Mir218-5p mimic. A Mir218-2 knockout was generated to assess the significance of miR-218-2 in a mammalian model. Mir218-2-5p expression was decreased in Mir218-2-/- embryos at E16.5. Mir218-2-/- decreased CD34+ angioblasts in the ureteric bud at E16.5 and were nonviable. Mir218-2+/- decreased peritubular capillary density at postnatal day 14 and increased serum creatinine after ischemia in adult mice. Systemic injection of miR-218-5p decreased serum creatinine after injury. These experiments demonstrate that miR-218 expression can be triggered by hypoxia and modulates EPC migration in the kidney.

Dietary phenylalanine requirements during early and late gestation in healthy pregnant women

BACKGROUND

Phenylalanine is an indispensable amino acid and, via tyrosine, is the precursor for the neurotransmitters dopamine, norepinephrine, and epinephrine. Currently, dietary requirements for phenylalanine during pregnancy are unknown.

OBJECTIVES

This study's aim was to determine phenylalanine requirements (in the presence of excess tyrosine) during early and late gestation using direct amino acid oxidation (DAAO; with l-[1-13C]phenylalanine) and indicator amino acid oxidation (IAAO; with l-[1-13C]leucine).

METHODS

Twenty-three healthy women (age: 30.4 ± 3.1 y, mean ± SD) were studied at a range of phenylalanine intakes (5.5-30.5 mg · kg-1 · d-1 in early and late pregnancy using DAAO, and 2.5-30.5 mg · kg-1 · d-1 in late pregnancy using IAAO) for a total of 76 study days. Test intakes were provided as 8 isocaloric and isonitrogenous meals with 1.5 g · kg-1 · d-1 protein and energy at 1.7 times the measured resting energy expenditure. Breath samples were analyzed on an isotope ratio mass spectrometer for 13C enrichment. Phenylalanine requirement was determined using a 2-phase linear regression crossover model to identify a breakpoint in 13CO2 production (representing the mean requirement) in response to phenylalanine intakes.

RESULTS

Phenylalanine requirement during early pregnancy was determined to be 15 mg · kg-1 · d-1 (95% CI: 10.4, 19.9 mg · kg-1 · d-1); during late pregnancy, it was determined to be 21 mg · kg-1 · d-1 by DAAO (95% CI: 17.4, 24.7 mg · kg-1 · d-1) and IAAO (95% CI: 10.5, 32.2 mg · kg-1 · d-1).

CONCLUSIONS

Our results suggest a higher requirement (40%) for phenylalanine during late pregnancy than during early pregnancy. Moreover, the early pregnancy requirements are higher than the previous adult male requirement (9.1 mg · kg-1 · d-1; 95% CI: 4.6, 13.6 mg · kg-1 · d-1), although the 95% CIs overlap. Both DAAO and IAAO methods provided similar breakpoints in late pregnancy, showing that the DAAO method was appropriate even though low phenylalanine intakes could not be tested. These results have potential implications for gestation stage-specific dietary phenylalanine recommendations in future.This trial was registered at clinicaltrials.gov as NCT02669381.

Outcomes of Selective Reduction of DCDA Twins Complicated by PV-PROM Compared with Expectant Management: A Case Series and Review of the Literature

OBJECTIVE

To report the outcomes of selective reduction (SR) in dichorionic twins complicated by pre-viable, premature rupture of membranes (PV-PROM).

METHODS

Retrospective case series. Ultrasound database was searched for cases of dichorionic twin pregnancy with PV-PROM, either managed conservatively or with SR. Chart reviews were done for these cases. Simple descriptive statistics were used where appropriate.

RESULTS

Twenty-two cases of expectantly managed dichorionic twins complicated by PV-PROM with delivery information were available for analysis. Mean GA at PV-PROM was 20.6 weeks, mean GA of delivery was 27.6 weeks, and the mean latency was 39.6 days. There were five cases of SR following PV-PROM in dichorionic twin pregnancies. Mean GA of PV-PROM was 17.0 weeks. Average time from PV-PROM to procedure was 2.5 weeks. Mean GA of delivery of the surviving fetus was 32.6 weeks (P = 0.20) with mean latency of 108 days (P = 0.06). Twelve additional cases have been published and are summarized along with our five cases.

CONCLUSION

There was a trend towards an increase in latency interval between cases of PV-PROM managed by SR and expectant management in our institution. When combined with the existing literature data, there may be an improvement in latency.

The Role of Nonenzymatic Post-translational Protein Modifications in Uremic Vascular Calcification

Considerable technological advances have enabled the identification and linkage of nonenzymatic post-translationally modified proteins to the pathogenesis of cardiovascular disease (CVD) in patients with kidney failure. Through processes such as the nonenzymatic carbamylation reaction as well as the formation of advanced glycation end products, we now know that protein modifications are invariably associated with the development of CVD beyond a mere epiphenomenon and this has become an important focus of nephrology research in recent years. Although the specific mechanisms by which protein modifications occurring in kidney failure that may contribute to CVD are diverse and include pathways such as inflammation and fibrosis, vascular calcification has emerged as a distinct pathological sequelae of protein modifications. In this review, we consider the biological mechanisms and clinical relevance of protein carbamylation and advanced glycation end products in CVD development with a focus on vascular calcification.

Klotho: A Major Shareholder in Vascular Aging Enterprises

Accelerated vascular aging is a condition that occurs as a complication of several highly prevalent inflammatory conditions such as chronic kidney disease, cancer, HIV infection and diabetes. Age-associated vascular alterations underlie a continuum of expression toward clinically overt cardiovascular disease. This has contributed to the striking epidemiologic transition whereby such noncommunicable diseases have taken center stage as modern-day global epidemics and public health problems. The identification of α-Klotho, a remarkable protein that confers powerful anti-aging properties has stimulated significant interest. In fact, emerging data have provided fundamental rationale for Klotho-based therapeutic intervention for vascular diseases and multiple other potential indications. However, the application of such discoveries in Klotho research remains fragmented due to significant gaps in our molecular understanding of Klotho biology, as well as hurdles in clinical research and experimental barriers that must first be overcome. These advances will be critical to establish the scientific platform from which future Klotho-based interventional trials and therapeutic enterprises can be successfully launched.

Pre-clinical model of severe glutathione peroxidase-3 deficiency and chronic kidney disease results in coronary artery thrombosis and depressed left ventricular function

Background

Chronic kidney disease (CKD) patients have deficient levels of glutathione peroxidase-3 (GPx3). We hypothesized that GPx3 deficiency may lead to cardiovascular disease in the presence of chronic kidney disease due to an accumulation of reactive oxygen species and decreased microvascular perfusion of the myocardium. Methods. To isolate the exclusive effect of GPx3 deficiency in kidney disease-induced cardiac disease, we studied the GPx3 knockout mouse strain (GPx3-/-) in the setting of surgery-induced CKD. Results. Ribonucleic acid (RNA) microarray screening of non-stimulated GPx3-/- heart tissue show increased expression of genes associated with cardiomyopathy including myh7, plac9, serpine1 and cd74 compared with wild-type (WT) controls. GPx3-/- mice underwent surgically induced renal mass reduction to generate a model of CKD. GPx3-/- + CKD mice underwent echocardiography 4 weeks after injury. Fractional shortening (FS) was decreased to 32.9 ± 5.8% in GPx3-/- + CKD compared to 62.0% ± 10.3 in WT + CKD (P < 0.001). Platelet aggregates were increased in the myocardium of GPx3-/- + CKD. Asymmetric dimethylarginine (ADMA) levels were increased in both GPx3-/- + CKD and WT+ CKD. ADMA stimulated spontaneous platelet aggregation more quickly in washed platelets from GPx3-/-. In vitro platelet aggregation was enhanced in samples from GPx3-/- + CKD. Platelet aggregation in GPx3-/- + CKD samples was mitigated after in vivo administration of ebselen, a glutathione peroxidase mimetic. FS improved in GPx3-/- + CKD mice after ebselen treatment.

Conclusion

These results suggest GPx3 deficiency is a substantive contributing factor to the development of kidney disease-induced cardiac disease.

The use of photoplethysmography for assessing hypertension

The measurement of blood pressure (BP) is critical to the treatment and management of many medical conditions. High blood pressure is associated with many chronic disease conditions, and is a major source of mortality and morbidity around the world. For outpatient care as well as general health monitoring, there is great interest in being able to accurately and frequently measure BP outside of a clinical setting, using mobile or wearable devices. One possible solution is photoplethysmography (PPG), which is most commonly used in pulse oximetry in clinical settings for measuring oxygen saturation. PPG technology is becoming more readily available, inexpensive, convenient, and easily integrated into portable devices. Recent advances include the development of smartphones and wearable devices that collect pulse oximeter signals. In this article, we review (i) the state-of-the-art and the literature related to PPG signals collected by pulse oximeters, (ii) various theoretical approaches that have been adopted in PPG BP measurement studies, and (iii) the potential of PPG measurement devices as a wearable application. Past studies on changes in PPG signals and BP are highlighted, and the correlation between PPG signals and BP are discussed. We also review the combined use of features extracted from PPG and other physiological signals in estimating BP. Although the technology is not yet mature, it is anticipated that in the near future, accurate, continuous BP measurements may be available from mobile and wearable devices given their vast potential.