In cardiac muscle, the intercalated disk (ID) at the longitudinal cell-edges of cardiomyocytes provides as a macromolecular infrastructure that integrates mechanical and electrical coupling within ...the heart. Pathophysiological disturbance in composition of this complex is well known to trigger cardiac arrhythmias and pump failure. The mechanisms underlying assembly of this important cellular domain in human heart is currently unknown.
We collected 18 specimens from individuals that died from non-cardiovascular causes. Age of the specimens ranged from a gestational age of 15 weeks through 11 years postnatal. Immunohistochemical labeling was performed against proteins comprising desmosomes, adherens junctions, the cardiac sodium channel and gap junctions to visualize spatiotemporal alterations in subcellular location of the proteins.
Changes in spatiotemporal localization of the adherens junction proteins (N-cadherin and ZO-1) and desmosomal proteins (plakoglobin, desmoplakin and plakophilin-2) were identical in all subsequent ages studied. After an initial period of diffuse and lateral labelling, all proteins were fully localized in the ID at approximately 1 year after birth. Nav1.5 that composes the cardiac sodium channel and the gap junction protein Cx43 follow a similar pattern but their arrival in the ID is detected at (much) later stages (two years for Nav1.5 and seven years for Cx43, respectively).
Our data on developmental maturation of the ID in human heart indicate that generation of the mechanical junctions at the ID precedes that of the electrical junctions with a significant difference in time. In addition arrival of the electrical junctions (Nav1.5 and Cx43) is not uniform since sodium channels localize much earlier than gap junction channels.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
After two doses of mRNA vaccine, health care workers had less viral neutralizing-antibody activity against the BA.4/5 and BA.2.12.1 omicron subvariants than against the BA.1 and BA.2 subvariants, but ...titers increased significantly with a booster dose.
Channelopathies are a diverse set of disorders associated with defects in ion channel (and transporter) function. Although the vast majority of channelopathies are linked with inherited mutations ...that alter ion channel biophysical properties, another group of similar disorders has emerged that alter ion channel synthesis, membrane trafficking, and or posttranslational modifications. In fact, some electrical and episodic disorders have now been identified that are not defects in the ion channel but instead reflect dysfunction in an ion channel (or transporter) regulatory protein. This review focuses on alternative paradigms for physiological disorders associated with protein biosynthesis, folding, trafficking, and membrane retention. Furthermore, the review highlights the role of aberrant posttranslational modifications in acquired channelopathies.
Recent reports of SARS-CoV-2 Omicron variant sub-lineages, BA.1, BA.1.1, and BA.2, have reignited concern over potential escape from vaccine- and infection-induced immunity. We examine the ...sensitivity of these sub-lineages and other major variants to neutralizing antibodies from mRNA-vaccinated and boosted individuals, as well as recovered COVID-19 patients, including those infected with Omicron. We find that all Omicron sub-lineages, especially BA.1 and BA.1.1, exhibit substantial immune escape that is largely overcome by mRNA vaccine booster doses. While Omicron BA.1.1 escapes almost completely from neutralization by early-pandemic COVID-19 patient sera and to a lesser extent from sera of Delta-infected patients, BA.1.1 is sensitive to Omicron-infected patient sera. Critically, all Omicron sub-lineages, including BA.2, are comparably neutralized by Omicron patient sera. These results highlight the importance of booster vaccine doses for protection against all Omicron variants and provide insight into the immunity from natural infection against Omicron sub-lineages.
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•BA.1.1, BA.1, and BA.2 escape neutralization by two-dose mRNA vaccinee sera•Booster vaccination recovers Omicron immunity to levels comparable to Delta•Sera from Omicron, but not D614G or Delta, COVID-19 patients neutralize Omicron•The Omicron “EPE214” insertion does not dictate neutralization resistance
The emerging SARS-CoV-2 Omicron variants may threaten existing COVID-19 immunity. Evans and colleagues examine immunity against the BA.1.1 and BA.2 variants, as well as prior SARS-CoV-2 variants, in two- and three-dose vaccinated individuals and recovered COVID-19 patients. Booster vaccination, but not two-dose vaccinee or non-Omicron-infected patient sera, neutralizes Omicron.
AnkyrinG (ankG) is highly enriched in neurons at axon initial segments (AISs) where it clusters Na+ and K+ channels and maintains neuronal polarity. How ankG becomes concentrated at the AIS is ...unknown. Here, we show that as neurons break symmetry, they assemble a distal axonal submembranous cytoskeleton, comprised of ankyrinB (ankB), αII-spectrin, and βII-spectrin, that defines a boundary limiting ankG to the proximal axon. Experimentally moving this boundary altered the length of ankG staining in the proximal axon, whereas disruption of the boundary through silencing of ankB, αII-spectrin, or βII-spectrin expression blocked AIS assembly and permitted ankG to redistribute throughout the distal axon. In support of an essential role for the distal cytoskeleton in ankG clustering, we also found that αII and βII-spectrin-deficient mice had disrupted AIS. Thus, the distal axonal cytoskeleton functions as an intra-axonal boundary restricting ankG to the AIS.
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► AnkyrinG (ankG) clustering follows and is dispensable for axon specification ► A distal cytoskeleton defines an intra-axonal boundary limiting ankG to the AIS ► Disruption of the distal cytoskeleton blocks ankG clustering and AIS assembly ► αII and βII-spectrin-deficient mice have disrupted AIS
Clustering of Na+ and K+ channels at the base of the axon by ankyrinG is vital for action potential generation. AnkyrinG is restricted to the axon initial segment by an unanticipated exclusion mechanism: the prior accumulation of ankyrinB in the distal axon acts as a barrier to the penetration of ankyrinG.
Abstract
Cigarette smoking is the most preventable risk factor related to cardiovascular morbidity and mortality. Tobacco usage has declined in recent years; however, the use of alternative nicotine ...delivery methods, particularly e-cigarettes, has increased exponentially despite limited data on their short- and long-term safety and efficacy. Due to their unique properties, the impact of e-cigarettes on cardiovascular physiology is not fully known. Here, we summarize both preclinical and clinical data extracted from short- and long-term studies on the cardiovascular effects of e-cigarette use. Current findings support that e-cigarettes are not a harm-free alternative to tobacco smoke. However, the data are primarily derived from acute studies. The impact of chronic e-cigarette exposure is essentially unstudied. To explore the uniqueness of e-cigarettes, we contemplate the cardiovascular effects of individual e-cigarette constituents. Overall, data suggest that exposure to e-cigarettes could be a potential cardiovascular health concern. Further preclinical research and randomized trials are needed to expand basic and clinical investigations before considering e-cigarettes safe alternatives to conventional cigarettes.
Abstract Reversible protein phosphorylation is central to a variety of cardiac processes including excitation-contraction coupling, Ca 2 + handling, cell metabolism, myofilament regulation, and ...cell-cell communication. While kinase pathways linked with elevated adrenergic signaling have been a major focus for the cardiovascular field over the past half century, new findings support the critical role of protein phosphatases in both health and disease. Protein phosphatase 2A (PP2A) is a central cardiac phosphatase that regulates diverse myocyte functions through a host of target molecules. Notably, multiple mechanisms have evolved to dynamically tune PP2A function, including modulation of the composition, phosphorylation, methylation, and localization of PP2A holoenzyme populations. Further, aberrations in this regulation of PP2A function may contribute to cardiac pathophysiology. In summary, PP2A is a critical regulatory molecule in both health and disease, with a myriad of targets in heart. Based on their unique structure, localization, and regulatory properties, PP2A subunits represent exciting therapeutic targets to modulate altered adrenergic signaling in cardiovascular disease.
Lessons From the Testosterone Trials Snyder, Peter J; Bhasin, Shalender; Cunningham, Glenn R ...
Endocrine reviews,
2018-June, Letnik:
39, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Abstract
The Testosterone Trials (TTrials) were a coordinated set of seven placebo-controlled,
double-blind trials in 788 men with a mean age of 72 years to determine the efficacy of
increasing the ...testosterone levels of older men with low testosterone. Testosterone
treatment increased the median testosterone level from unequivocally low at baseline to
midnormal for young men after 3 months and maintained that level until month 12. In the
Sexual Function Trial, testosterone increased sexual activity, sexual desire, and erectile
function. In the Physical Function Trial, testosterone did not increase the distance
walked in 6 minutes in men whose walk speed was slow; however, in all TTrial participants,
testosterone did increase the distance walked. In the Vitality Trial, testosterone did not
increase energy but slightly improved mood and depressive symptoms. In the Cognitive
Function Trial, testosterone did not improve cognitive function. In the Anemia Trial,
testosterone increased hemoglobin in both men who had anemia of a known cause and in men
with unexplained anemia. In the Bone Trial, testosterone increased volumetric bone mineral
density and the estimated strength of the spine and hip. In the Cardiovascular Trial,
testosterone increased the coronary artery noncalcified plaque volume as assessed using
computed tomographic angiography. Although testosterone was not associated with more
cardiovascular or prostate adverse events than placebo, a trial of a much larger number of
men for a much longer period would be necessary to determine whether testosterone
increases cardiovascular or prostate risk.
The Testosterone Trials were conducted to determine if testosterone treatment would
benefit older men with low testosterone. This report describes the Trials' development and
results and the lessons learned.
The complex architecture of the human atria may create physical substrates for sustained re-entry to drive atrial fibrillation (AF). The existence of sustained, anatomically defined AF drivers in ...humans has been challenged partly due to the lack of simultaneous endocardial-epicardial (Endo-Epi) mapping coupled with high-resolution 3D structural imaging.
Coronary-perfused human right atria from explanted diseased hearts (n = 8, 43-72 years old) were optically mapped simultaneously by three high-resolution CMOS cameras (two aligned Endo-Epi views (330 µm2 resolution) and one panoramic view). 3D gadolinium-enhanced magnetic resonance imaging (GE-MRI, 80 µm3 resolution) revealed the atrial wall structure varied in thickness (1.0 ± 0.7-6.8 ± 2.4 mm), transmural fiber angle differences, and interstitial fibrosis causing transmural activation delay from 23 ± 11 to 43 ± 22 ms at increased pacing rates. Sustained AF (>90 min) was induced by burst pacing during pinacidil (30-100 µM) perfusion. Dual-sided sub-Endo-sub-Epi optical mapping revealed that AF was driven by spatially and temporally stable intramural re-entry with 107 ± 50 ms cycle length and transmural activation delay of 67 ± 31 ms. Intramural re-entrant drivers were captured primarily by sub-Endo mapping, while sub-Epi mapping visualized re-entry or 'breakthrough' patterns. Re-entrant drivers were anchored on 3D micro-anatomic tracks (15.4 ± 2.2 × 6.0 ± 2.3 mm2, 2.9 ± 0.9 mm depth) formed by atrial musculature characterized by increased transmural fiber angle differences and interstitial fibrosis. Targeted radiofrequency ablation of the tracks verified these re-entries as drivers of AF.
Integrated 3D structural-functional mapping of diseased human right atria ex vivo revealed that the complex atrial microstructure caused significant differences between Endo vs. Epi activation during pacing and sustained AF driven by intramural re-entry anchored to fibrosis-insulated atrial bundles.
Abstract
Context
Studies of the possible cardiovascular risk of testosterone treatment are inconclusive.
Objective
To determine the effect of testosterone treatment on cardiovascular biomarkers in ...older men with low testosterone.
Design
Double-blind, placebo-controlled trial.
Setting
Twelve academic medical centers in the United States.
Participants
In all, 788 men ≥65 years old with an average of two serum testosterone levels <275 ng/dL who were enrolled in The Testosterone Trials.
Intervention
Testosterone gel, the dose adjusted to maintain the testosterone level in the normal range for young men, or placebo gel for 12 months.
Main Outcome Measures
Serum markers of cardiovascular risk, including lipids and markers of glucose metabolism, fibrinolysis, inflammation, and myocardial damage.
Results
Compared with placebo, testosterone treatment significantly decreased total cholesterol (adjusted mean difference, −6.1 mg/dL; P < 0.001), high-density lipoprotein cholesterol (adjusted mean difference, −2.0 mg/dL; P < 0.001), and low-density lipoprotein cholesterol (adjusted mean difference, −2.3 mg/dL; P = 0.051) from baseline to month 12. Testosterone also slightly but significantly decreased fasting insulin (adjusted mean difference, −1.7 µIU/mL; P = 0.02) and homeostatic model assessment‒insulin resistance (adjusted mean difference, −0.6; P = 0.03). Testosterone did not change triglycerides, d-dimer, C-reactive protein, interleukin 6, troponin, glucose, or hemoglobin A1c levels more than placebo.
Conclusions and Relevance
Testosterone treatment of 1 year in older men with low testosterone was associated with small reductions in cholesterol and insulin but not with other glucose markers, markers of inflammation or fibrinolysis, or troponin. The clinical importance of these findings is unclear and requires a larger trial of clinical outcomes.
Compared with placebo, testosterone treatment of older men with low testosterone was associated with small reductions in total, HDL, and LDL cholesterol and in insulin and HOMA-IR but not glucose.
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