ProANP31-67 ameliorates adverse cardiac remodeling and improves systolic and diastolic functions in a preclinical model of cardiorenal syndrome

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): South-Eastern Norway Regional Health Authority (HSØ-RHF, Project No. 25674)

Background

The cardiac hormone proANP31-67, a linear fragment of the N-terminal Atrial Natriuretic Peptide, has known enhancing renal effects. More recently, we described the cardio protective effects of this hormone in a model of chronic hypertension. More specifically, independently of the blood pressure level, proANP31-67 improved diastolic function, attenuated cardiac fibrosis, and reduced hypertrophy.

Purpose

The current study was designed to assess the cardiorenal effects of proANP31-67 in a rodent model of hampered renal function, followed by cardiac injury produced by ischemia/reperfusion (I/R).

Methods

Right uninephrectomy (UNX) was performed in Wistar rats (n=28). Sixteen weeks after UNX, rats underwent cardiac I/R injury and randomly assigned to proANP31-67 (50 ng/kg/day s.c., n=15) or Vehicle (n=13) for four weeks post I/R. Echocardiographic examinations were performed at baseline (before UNX), 16 weeks after UNX, and four weeks after I/R. At the end of the study, cardiomyocytes were isolated and tissue samples were collected.

Results

Chronic UNX resulted in diastolic impairment (E/A: 1.47±0.08 at baseline vs 0.98±0.14 at 16 wks post UNX, p=0.0010). I/R further accentuated the development of the cardiorenal syndrome, and induced a mild systolic dysfunction in the placebo treated animals. However, four weeks of treatment with proANP31-67 preserved systolic function (EF: 62±3% placebo vs 74±2% proANP31-67, p<0.0001), and reverted the diastolic dysfunction (E/A: 0.72±0.15 placebo vs 1.24±0.11 proANP31-67, p=0.0134). ProANP31-67 ameliorated the adverse cardiac remodeling (i.e., reduction in the cardiomyocyte cross-sectional area and interstitial fibrosis), enhanced Ca2+ handling, and improved cardiomyocyte t-tubules´ structural changes compared to vehicle. At the cellular level, in vitro experiments demonstrated the direct effect of proANP31-67 on cardiomyocyte hypertrophy (assessed by [3H]-leucine incorporation) induced by endothelin 1 and angiotensin II.

Conclusion

ProANP31-67 has a direct cardiomyocyte protective effect, leading to an improvement in Ca2+ homeostasis and t-tubules´ structures and, prevents the development of systolic and diastolic dysfunction in a pre-clinical model of cardiorenal syndrome.

Cardiomyocyte substructure reverts to an immature phenotype during heart failure

Key points

As reactivation of the fetal gene program has been implicated in pathological remodelling during heart failure (HF), we examined whether cardiomyocyte subcellular structure and function revert to an immature phenotype during this disease.

Surface and internal membrane structures appeared gradually during development, and returned to a juvenile state during HF. Similarly, dyadic junctions between the cell membrane and sarcoplasmic reticulum were progressively ‘packed’ with L‐type Ca²⁺ channels and ryanodine receptors during development, and ‘unpacked’ during HF.

Despite similarities in subcellular structure, dyads were observed to be functional from early developmental stages, but exhibited an impaired ability to release Ca²⁺ in failing cardiomyocytes.

Thus, while immature and failing cardiomyocytes share similarities in subcellular structure, these do not fully account for the marked impairment of Ca²⁺ homeostasis observed in HF.

Abstract

Reactivation of the fetal gene programme has been implicated as a driver of pathological cardiac remodelling. Here we examined whether pathological remodelling of cardiomyocyte substructure and function during heart failure (HF) reflects a reversion to an immature phenotype. Using scanning electron microscopy, we observed that Z‐grooves and t‐tubule openings at the cell surface appeared gradually during cardiac development, and disappeared during HF. Confocal and super‐resolution imaging within the cell interior revealed similar structural parallels; disorganization of t‐tubules in failing cells was strikingly reminiscent of the late stages of postnatal development, with fewer transverse elements and a high proportion of longitudinal tubules. Ryanodine receptors (RyRs) were observed to be laid down in advance of developing t‐tubules and similarly ‘orphaned’ in HF, although RyR distribution along Z‐lines was relatively sparse. Indeed, nanoscale imaging revealed coordinated packing of L‐type Ca²⁺ channels and RyRs into dyadic junctions during development, and orderly unpacking during HF. These findings support a ‘last in, first out’ paradigm, as the latest stages of dyadic structural development are reversed during disease. Paired imaging of t‐tubules and Ca²⁺ showed that the disorganized arrangement of dyads in immature and failing cells promoted desynchronized and slowed Ca²⁺ release in these two states. However, while developing cells exhibited efficient triggering of Ca²⁺ release at newly formed dyads, dyadic function was impaired in failing cells despite similar organization of Ca²⁺ handling proteins. Thus, pathologically deficient Ca²⁺ homeostasis during HF is only partly linked to the re‐emergence of immature subcellular structure, and additionally reflects lost dyadic functionality.

As reactivation of the fetal gene program has been implicated in pathological remodelling during heart failure (HF), we examined whether cardiomyocyte subcellular structure and function revert to an immature phenotype during this disease.

Surface and internal membrane structures appeared gradually during development, and returned to a juvenile state during HF. Similarly, dyadic junctions between the cell membrane and sarcoplasmic reticulum were progressively ‘packed’ with L‐type Ca²⁺ channels and ryanodine receptors during development, and ‘unpacked’ during HF.

Despite similarities in subcellular structure, dyads were observed to be functional from early developmental stages, but exhibited an impaired ability to release Ca²⁺ in failing cardiomyocytes.

Thus, while immature and failing cardiomyocytes share similarities in subcellular structure, these do not fully account for the marked impairment of Ca²⁺ homeostasis observed in HF.

Sudden unexpected death in a female fitness athlete, with a possible connection to the use of anabolic androgenic steroids (AAS) and ephedrine

The use of anabolic androgenic steroids (AAS) has been associated with different adverse effects, some of which potentially lethal. Most users of AAS are male, but the prevalence of such use appears to be increasing in females. Here we present a sudden unexpected death in a female fitness athlete with a possible connection to use of doping agents.

Environmental tobacco smoke exposure during childhood is associated with increased prevalence of asthma in adults

OBJECTIVE

To examine if exposure to environmental tobacco smoke (ETS) during childhood has an impact on asthma prevalence in adults, and to identify the amount of nuisance from ETS and other lower airway irritants (LAWIs) in a city population.

DESIGN

A postal survey.

SETTING

The municipality of Orebro, Sweden.

PARTICIPANTS

A total of 8,008 randomly selected inhabitants aged 15 to 69 years.

MEASUREMENTS

Exposures, airway symptoms, and respiratory history were assessed using a questionnaire.

RESULTS

The response rate was 84%. In never-smokers with childhood ETS exposure, the prevalence of physician-diagnosed asthma was 7.6% vs 5.9% in nonexposed subjects (p = 0.036). In never-smokers without a family history of asthma, the prevalence of physician-diagnosed asthma in subjects reporting childhood ETS exposure was 6.8% vs 3.8% in nonexposed subjects (p < 0.001). Subjects with childhood ETS exposure were more likely to start smoking in adulthood. The prevalence of ever-smokers was 54.5% vs 33.8% (p < 0.0001) in nonexposed subjects. ETS was the most commonly reported LAWI in the total sample (21%), followed by exercise in cold air (20%), dust (19%), exercise (16%), perfume (15%), cold air (12%), pollen (10%), and pets (8%). All LAWIs were more frequently reported by women.

CONCLUSIONS

Childhood exposure to ETS is associated with an increased prevalence of asthma among adult never-smokers, especially in nonatopic subjects. Children exposed to ETS are also more likely to become smokers. ETS is as a major LAWI.

A complex background in children and adolescents with psychiatric disorders: developmental delay, dyslexia, heredity, slow cognitive processing and adverse social factors in a multifactorial entirety

A consecutive cohort of 112 children, 42 girls and 70 boys, aged 5-17 years, receiving child psychiatric inpatient care, was investigated regarding the probability of a complex background of concomitant biological and social factors. Most of the subjects showed maladjustment and depressive states, school problems, problems with peers, psychosomatic complaints and anxiety. A very high rate of factors indicating neurodevelopmental dysfunctions was found particularly in boys, who exhibited developmental delay, dyslexia, heredity for dyslexia, and a slow complex reaction time (CRT) - suggesting slow cognitive processing - considered an impairment in itself. Further, many children obtained errors on the CRT task, indicating attention deficit and deterioration during the test, pointing toward exhaustion. The social background displayed frequent problems such as broken homes, care outside the biological home, and disordered and/or abusing parents. The biological and social factors created a complex web, predisposing the child to primary, secondary and/or comorbidity problems, and leading to an interactive process reducing the child's psychosocial capacity and competence. A pattern was developed of an impaired child, living in an inadequate/insufficient family milieu in a modern society, with increasing demands on children.

Social competence and emotional/behaviour problems in 6-16 year-old Swedish school children

Social competence and emotional/behavioural problems as reported by parents on a Swedish version of the Child Behaviour Checklist (CBCL) were examined in 1308 Swedish school-aged children/adolescents recruited from a stratified, random sample of schools in urban, semirural, and rural areas in Uppsala County, Sweden, and from Stockholm, the capital city of Sweden. The overall response rate was 80.6%. Few gender differences were found, but adolescents received higher problem scores and higher social competence scores than the younger children. Children from the middle SES groups were regarded as having higher social competence levels, and children from the lower SES groups had higher emotional/behaviour problem scores. Children from the larger cities consistently obtained higher problem scores. Those who had received help during the previous year because of psychological problems (2%) had much higher problems scores than those who had not received help. The levels of emotional/behavioural problems in children and adolescents in the present sample seem to be comparable to those reported in similar Scandinavian studies where the CBCL has been used. However, they were considerably lower than those commonly reported in epidemiological studies of children/adolescents from other countries and cultures.

Mental and somatic health and social adjustment in ordinary school children during childhood and adolescence related to central nervous functions as expressed by a complex reaction time

A cohort of ordinary Swedish children were followed up from school entry through childhood and adolescence and checked retrospectively from birth to the age of 6 years regarding psychiatric and physical health and contact with the social welfare authorities. The children were allocated to different risk groups at age 7 on the basis of their psycho-physical development expressed as complex reaction time (CRT). It was previously shown that many of the slow CRT children have problems in psychomotor and language development at school, and that many leave compulsory school with poor achievements in Swedish and gymnastics as continuing signs of their developmental delay. This study shows that slow CRT children have an increased prevalence of child psychiatric problems. At an early age there were symptoms of aggression, hyperactivity and withdrawal in conjunction with developmental delay. During adolescence, depression, maladjustment and psycho-somatic disorders were prominent features, often in association with developmental delay, dyslexia and poor motoric skill. These children could have a disadvantage at school and in society and they felt themselves "handicapped" and were stressed by feelings of limited future possibilities. In adolescence, many of them were in need of help, especially financial aid from the social welfare services. The findings stress that a slow cognitive processing ability seen as a slow CRT must be considered a handicap of importance and a risk-factor in the society of today, with primary or secondary psychic and social manifestations often in a multifactorial setting of biological co-morbidity and family problems. In contrast, an advanced CNS development with a fast CRT may be seen as a protective factor.

Effects of zolpidem on sleep architecture, night time ventilation, daytime vigilance and performance in heavy snorers

1. In a double-blind, crossover, placebo controlled trial, zolpidem 10 mg, a new imidazopyridine hypnotic drug, was administered in a single dose to 10 healthy non-obese heavy snorers. 2. Nocturnal polysomnography showed that zolpidem increased total sleep time, sleep efficiency and the percentage of stage 2. 3. Respiratory monitoring showed that zolpidem did not modify the percentage of total sleep time spent snoring. The percentages of total sleep time with a SaO2 < 4% of the baseline value and with a SaO2 < 90% and the mean SaO2 were also unchanged with zolpidem. The respiratory disturbance index was modestly increased by zolpidem although in all but one subject it remained < 5 with both treatments. 4. Zolpidem intake did not impair daytime vigilance and performance evaluated the day after.

School achievement and school adaptation in children in relation to CNS development as assessed by a complex reaction time measured on school entry--a follow-up

Schoolchildren aged seven years underwent a complex reaction time (CRT) measurement and were followed up regarding language achievements and performance in gymnastics during the nine years of compulsory school. An analysis was made of the correlation between school results and CRT findings. In grade 3, there were large differences in psychomotor development between children with fast and slow CRT in both sexes. Only minor differences in school achievement were seen between girls in different CRT groups. Among the boys, however, many with a slow CRT were considered handicapped in language development, with dyslexia as the most important problem in addition to poor motoricity. They left compulsory school with poor results in Swedish, their native language, and gymnastics, and with a certificate that may reduce their changes of future studies and employment. The boys in general were inferior to the girls. The slow CRT boys, who were mainly considered to be developmentally delayed, also carried a risk of social maladjustment. It would appear to be important that psychophysical maturity receives attention at school, in addition to emotional and social factors. The school health services have an important responsibility in this respect.

Effect of zolpidem during sleep on ventilation and cardiovascular variables in normal subjects

A double-blind study comparing the effect of zolpidem 10 mg, and placebo, on sleep architecture, nocturnal ventilation, cardiovascular parameters (heart rate, systolic, diastolic and mean blood pressures) was carried out. Ten healthy middle-aged males took part in the study. No significant differences were found between zolpidem and placebo in relation to sleep architecture. Mean respiratory disturbance index (RDI) and SaO2 values (mean SaO2, time spent with SaO2 < 90%) were similar under both conditions. The diastolic and mean blood pressure readings taken from REM periods which occurred during the first third of the night were significantly higher with zolpidem. No changes in systolic blood pressure or heart rate were found with zolpidem in comparison to placebo.

Chloroquine in malaria. Isn't it time for revision of prophylaxis schedules?

Two antimalarial prophylactic regimens were compared in healthy subjects belonging to the flying personnel of Scandinavian Airlines System. Regimen I: 310 mg chloroquine (CQ) base was given once weekly, starting the week prior to departure to the endemic area, then weekly during presence there and for four weeks after return. Regimen II: a loading dose of 620 mg chloroquine base was given at the latest 48 h prior to departure to the endemic area, followed by 310 mg base weekly throughout the visit. Blood samples were analysed by HPLC for CQ and its major metabolite desethylchloroquine (CQM). Regimen I gave suboptimal whole blood concentrations of CQ and CQM at the end of the first week of treatment. Regimen II gave prophylactic concentrations from the beginning of visit up to 6 weeks after departure from the endemic area. Both regimens were well tolerated, but Regimen II appeared better accepted by the volunteers due to its shorter duration.

The role of personality factors and suggestion in placebo effect during mental stress test

The aims of this study were first of all to document a placebo effect on systolic blood pressure and heart rate during mental arithmetic induced stress and secondly to assess the role of suggestion in producing this effect. Two types of placebo were used, a simple placebo and a placebo with an implied therapeutic action. Both were compared with alprazolam. A placebo response was seen in just over half of the volunteers when the cardiovascular changes to mental arithmetic induced stress in healthy volunteers were measured. This response appeared to be unaffected by the suggested therapeutic effect. Dominant, independent subjects, identified using the Cattell 16 PF personality test were less likely to respond to placebo. Alprazolam (0.5 mg) did not prevent, to a significantly greater degree than placebo, the systolic blood pressure or heart rate increases provoked by the mental stress.

School readiness and CNS maturity: relation to psychophysical and psychosocial development and to early school achievement

In randomly selected schools 113 girls and 102 boys were subjected to a School Readiness (SR) test and to a Complex Reaction Time (CRT) measurement at the age of 7. Their psychophysical development, social adjustment and school achievement were assessed by teachers and by means of self-ratings during the first 3 school years. The developmental outcome of the children seemed principally related to CNS-maturity as measured by CRT, and not to the SR test scores. A CNS-dysfunction, indicated by slow CRT, seemed to be an essential handicap during the early school years, impairing particularly the boys' language and motor development and their school achievement and causing feelings of inferiority. This handicap, which is mainly a developmental delay, should thus be taken into consideration when assessing school maturity. Early detection of this handicap might enable us to take preventive measures with regard to these children.