Inhibition of myocardial cathepsin-L release during reperfusion following myocardial infarction improves cardiac function and reduces infarct size

AIMS

Identifying novel mediators of lethal myocardial reperfusion injury that can be targeted during primary percutaneous coronary intervention (PPCI) is key to limiting the progression of patients with ST-elevation myocardial infarction (STEMI) to heart failure. Here, we show through parallel clinical and integrative preclinical studies the significance of the protease cathepsin-L on cardiac function during reperfusion injury.

METHODS AND RESULTS

We found that direct cardiac release of cathepsin-L in STEMI patients (n = 76) immediately post-PPCI leads to elevated serum cathepsin-L levels and that serum levels of cathepsin-L in the first 24 h post-reperfusion are associated with reduced cardiac contractile function and increased infarct size. Preclinical studies demonstrate that inhibition of cathepsin-L release following reperfusion injury with CAA0225 reduces infarct size and improves cardiac contractile function by limiting abnormal cardiomyocyte calcium handling and apoptosis.

CONCLUSION

Our findings suggest that cathepsin-L is a novel therapeutic target that could be exploited clinically to counteract the deleterious effects of acute reperfusion injury after an acute STEMI.

Exploring the Motivational Drivers of Young Adults with Diabetes for Participation in Kidney Research

Understanding motivational drivers and barriers to patient participation in diabetes research are important to ensure research is relevant and valuable. Young adults with type 1 diabetes (T1D) completed a 31-question qualitative survey evaluating participant experience, understanding, and motivators and barriers to research involvement. A total of 35 participants, 19–28 years of age, 60% female, completed the survey. Motivating factors included personal benefit, relationship with the study team, curiosity, financial compensation, altruism, and nostalgia. Older participants (>22 years) reported higher levels of trust in the study team (p = 0.02) and their relationship with the study team positively influenced their decision to participate (p = 0.03). Financial compensation was a strong motivator for participants with higher education (p = 0.02). Age, sex, education level, and trust in the study team influenced participants’ understanding. Barriers included logistics and lack of familial support. Important motivational drivers and barriers to participation in research by young adults with T1D must be considered to increase research engagement and facilitate the discovery of new knowledge.

Regulation of connexin 43 by interleukin 1β in adult rat cardiac fibroblasts and effects in an adult rat cardiac myocyte: fibroblast co-culture model

Connexin 43 expression (Cx43) is increased in cardiac fibroblasts (CFs) following myocardial infarction. Here, potential mediators responsible for increasing Cx43 expression and effects of differential CF phenotype on cardiac myocyte (CM) function were investigated. Stimulating adult rat CFs with proinflammatory mediators revealed that interleukin 1β (IL-1β) significantly enhanced Cx43 levels through the IL-1β pathway. Additionally, IL-1β reduced mRNA levels of the myofibroblast (MF) markers: (i) connective tissue growth factor (CTGF) and (ii) α smooth muscle actin (αSMA), compared to control CFs. A co-culture adult rat CM:CF model was utilised to examine cell-to-cell interactions. Transfer of calcein from CMs to underlying CFs suggested functional gap junction formation. Functional analysis revealed contraction duration (CD) of CMs was shortened in co-culture with CFs, while treatment of CFs with IL-1β reduced this mechanical effect of co-culture. No effect on action potential rise time or duration of CMs cultured with control or IL-1β-treated CFs was observed. These data demonstrate that stimulating CFs with IL-1β increases Cx43 and reduces MF marker expression, suggesting altered cell phenotype. These changes may underlie the reduced mechanical effects of IL-1β treated CFs on CD of co-cultured CMs and therefore have an implication for our understanding of heterocellular interactions in cardiac disease.

Gene Therapy With Angiotensin-(1-9) Preserves Left Ventricular Systolic Function After Myocardial Infarction

Background

Angiotensin-(1-9) [Ang-(1-9)] is a novel peptide of the counter-regulatory axis of the renin-angiotensin-aldosterone system previously demonstrated to have therapeutic potential in hypertensive cardiomyopathy when administered via osmotic mini-pump. Here, we investigate whether gene transfer of Ang-(1-9) is cardioprotective in a murine model of myocardial infarction (MI).

Objectives

The authors evaluated effects of Ang-(1-9) gene therapy on myocardial structural and functional remodeling post-infarction.

Methods

C57BL/6 mice underwent permanent left anterior descending coronary artery ligation and cardiac function was assessed using echocardiography for 8 weeks followed by a terminal measurement of left ventricular pressure volume loops. Ang-(1-9) was delivered by adeno-associated viral vector via single tail vein injection immediately following induction of MI. Direct effects of Ang-(1-9) on cardiomyocyte excitation/contraction coupling and cardiac contraction were evaluated in isolated mouse and human cardiomyocytes and in an ex vivo Langendorff-perfused whole-heart model.

Results

Gene delivery of Ang-(1-9) reduced sudden cardiac death post-MI. Pressure volume measurements revealed complete restoration of end-systolic pressure, ejection fraction, end-systolic volume, and the end-diastolic pressure volume relationship by Ang-(1-9) treatment. Stroke volume and cardiac output were significantly increased versus sham. Histological analysis revealed only mild effects on cardiac hypertrophy and fibrosis, but a significant increase in scar thickness. Direct assessment of Ang-(1-9) on isolated cardiomyocytes demonstrated a positive inotropic effect via increasing calcium transient amplitude and contractility. Ang-(1-9) increased contraction in the Langendorff model through a protein kinase A–dependent mechanism.

Conclusions

Our novel findings showed that Ang-(1-9) gene therapy preserved left ventricular systolic function post-MI, restoring cardiac function. Furthermore, Ang-(1-9) directly affected cardiomyocyte calcium handling through a protein kinase A–dependent mechanism. These data emphasized Ang-(1-9) gene therapy as a potential new strategy in the context of MI.

Preanalytical study of fetuin-A: effect of sample type, processing speed and freeze-thaw cycles

BACKGROUND

It has been suggested that fetuin-A may be a potential biomarker of cardiometabolic disease. However, few studies have investigated preanalytical factors that might impact the measurement of fetuin-A in the circulation. This pilot study aimed to investigate the preanalytical variables of sample type, timing of sample centrifugation and the impact of freeze-thaw cycles on the concentration of fetuin-A in serum or EDTA-plasma.

METHODS

Blood samples were taken from 19 male or female healthy volunteers, aged 18-70 years, and left at ambient room temperature for 2 h or 48 h. The tubes were then centrifuged, serum and EDTA-plasma separated, and fetuin-A concentrations measured using a commercially available enzyme-linked immunosorbent assay (ELISA).

RESULTS

There was no significant difference between the concentrations of fetuin-A in EDTA-plasma and serum following separation from whole blood at 2 h postcollection (P=0.78). The median (interquartile range) concentrations of fetuin-A in EDTA-plasma separated at 2 h and 48 h postcollection were 589 µg/mL (484-703 µg/mL) and 767 µg/mL (687-942 µg/mL), respectively (P<0.0005). For serum, equivalent concentrations were 606 µg/mL (501-669 µg/mL) at 2 h and 607 µg/mL (564-757 µg/mL) at 48 h postcollection (P=0.06). Fetuin-A concentrations measured in EDTA-plasma and serum showed no significant change following three freeze-thaw cycles in samples separated at 2 h postcollection (EDTA-plasma P=0.16; serum P=0.89).

CONCLUSION

This small pilot study has shown that serum is preferable to EDTA-plasma for the measurement of fetuin-A. It has also shown that fetuin-A appears to be as stable after three freeze-thaw cycles as it is after one.

CD38 as a prognostic marker in chronic lymphocytic leukaemia at a single New Zealand centre: patient survival in comparison to age- and sex-matched population data

AIM

The aim of this study is to determine whether the analysis of CD38 expression by chronic lymphocytic leukaemia (CLL) cells provides useful additional prognostic information.

METHODS

Clinical, laboratory, overall survival (OS) and treatment-free survival (TFS) data were collected on 130 CLL patients who had CD38 expression analysed at Canterbury Health Laboratories, New Zealand (NZ) during 1998-2008.

RESULTS

The detection of any level of CD38 expression by CLL cells was associated with a significantly shorter OS and TFS. When analysis was restricted to Binet stage A patients, CD38 expression identified a subset of patients (21%) who, in common with Binet stage B/C patients, had a significantly shorter OS and TFS (P<0.0015), and a TFS at 4 years of <10%. In contrast, CD38-negative Binet stage A patients had an OS that was not significantly different from that of an age/sex-matched NZ population and a 5-year TFS of 77%.

CONCLUSION

This study indicates that, when combined with clinical staging, the presence of any detectable CD38 expression can be used to further improve the identification of CLL patients with more aggressive disease (i.e. Binet stage B/C or Binet stage A and CD38 positive). This will allow better identification of those patients requiring more intensive monitoring and also allow improved patient counselling regarding prognosis.

Managing sedation withdrawal in children who undergo prolonged PICU admission after discharge to the ward

Children who undergo a prolonged stay within the intensive care unit require adequate sedation and analgesia. During the recovery phase there will need to be a period of sedation withdrawal to prevent occurrence of an abstinence syndrome. We present a strategy developed within our hospital for managing this process which uses the resource of the Pain Service, along with guidelines to help prevent the development of withdrawal, and a plan for managing any signs of abstinence which occur.

Behaviors, attitudes, and knowledge of low-income consumers regarding nutrition labels

This exploratory study interviewed 130 participants in federal food assistance programs and 51 low-income nonparticipants to assess their behaviors and attitudes toward and awareness of the nutrition label. Regarding label use, 35.4 percent of participants and 45.1 percent of nonparticipants seldom/never read labels while grocery shopping, 31.5 percent of participants and 19.6 percent of nonparticipants sometimes read them, and 33.1 percent of participants and 35.3 percent of nonparticipants always/frequently read labels in the grocery store. In addition, 38.5 percent of participants and 41.2 percent of nonparticipants seldom/never read labels at home, 33.1 percent of participants and 27.5 percent of nonparticipants sometimes read them, and 28.5 percent of participants and 31.4 percent of nonparticipants always/frequently read labels at home. There were no significant differences between mean scores of participants and nonparticipants on how to use the nutrition label. Findings challenge nutritionists working with low-income individuals to develop more learning opportunities that teach how to use nutrition labels.

Pain relief and wound care in a young woman with special needs

This article focuses on a teenage girl with cerebral palsy admitted for an orthopaedic procedure, and highlights the problems of pain and wound management discussed in this journal's Challenges in Wound Care study days.

Effects of socioeconomic status on the obesity knowledge of adolescents from six Latin American cities

OBJECTIVE

To examine the effects of socioeconomic status (SES) on the obesity knowledge of adolescents in six Latin American cities.

DESIGN

Data were collected using an anonymous, self-administered questionnaire consisting of demographic questions and a 25-item multiple-choice obesity knowledge test. Test items were clustered under five topics: the fat and calorie content of foods and beverages; weight loss methods; energy expenditure; food preparation methods; and the relationship between obesity and health.

SUBJECTS

A total of 1272 ninth grade students from higher and lower SES families were recruited at schools in Buenos Aires, Argentina (n=195); Guatemala City, Guatemala (n=212); Havana, Cuba (n=213); Lima, Peru (n=218); Panama City, Panama (n=195); and Santiago, Chile (n=239).

RESULTS

Mean test scores reflected a low level of obesity knowledge among adolescents from higher and lower SES groups in all six cities. Nevertheless, a trend for higher scores emerged in favor of adolescents from wealthier families. This income effect persisted after controlling for gender and weight status. The weakest knowledge areas among youth from the higher SES groups were food preparation methods and the relationship between obesity and health while those for adolescents from the lower SES groups were the fat and calorie content of foods and beverages and the relationship between obesity and health. Classroom instruction about obesity was generally more available to students from the higher SES groups. The majority of adolescents from both SES groups were interested in learning more about weight loss methods, energy expenditure, and the fat and calorie content of foods and beverages. The topic of least interest was the relationship between obesity and health.

CONCLUSION

These preliminary findings suggest a need for more obesity education programs for adolescents, especially for those living in poverty.

Literacy of women attending family planning clinics in Virginia and reading levels of brochures on HIV prevention

A study estimating the extent to which the reading level of HIV educational brochures matches the reading ability (measured by educational attainment) of women attending public family planning clinics in Virginia shows that the mean reading level of the brochures sampled is grade 9.9. The educational attainment of 18% of Virginia family planning clients falls below this level. The mean reading level of brochures targeted to adolescents (grade 8.3) and the mean reading level of those targeted to minority women (grade 9.1) are significantly lower than the mean for all sampled brochures. Use of the targeted brochures would improve access to information on HIV prevention for 16% of adolescents and 6% of minority women who attend family planning clinics in Virginia.