Interdependent changes of nuclear lamins, nuclear pore complexes, and ploidy regulate cellular regeneration and stress response in the heart

In adult mammals, many heart muscle cells (cardiomyocytes) are polyploid, do not proliferate (post-mitotic), and, consequently, cannot contribute to heart regeneration. In contrast, fetal and neonatal heart muscle cells are diploid, proliferate, and contribute to heart regeneration. We have identified interdependent changes of the nuclear lamina, nuclear pore complexes, and DNA-content (ploidy) in heart muscle cell maturation. These results offer new perspectives on how cells alter their nuclear transport and, with that, their gene regulation in response to extracellular signals. We present how changes of the nuclear lamina alter nuclear pore complexes in heart muscle cells. The consequences of these changes for cellular regeneration and stress response in the heart are discussed.

Histone deacetylase 1 controls cardiomyocyte proliferation during embryonic heart development and cardiac regeneration in zebrafish

In contrast to mammals, the zebrafish maintains its cardiomyocyte proliferation capacity throughout adulthood. However, neither the molecular mechanisms that orchestrate the proliferation of cardiomyocytes during developmental heart growth nor in the context of regeneration in the adult are sufficiently defined yet. We identified in a forward genetic N-ethyl-N-nitrosourea (ENU) mutagenesis screen the recessive, embryonic-lethal zebrafish mutant baldrian (bal), which shows severely impaired developmental heart growth due to diminished cardiomyocyte proliferation. By positional cloning, we identified a missense mutation in the zebrafish histone deacetylase 1 (hdac1) gene leading to severe protein instability and the loss of Hdac1 function in vivo. Hdac1 inhibition significantly reduces cardiomyocyte proliferation, indicating a role of Hdac1 during developmental heart growth in zebrafish. To evaluate whether developmental and regenerative Hdac1-associated mechanisms of cardiomyocyte proliferation are conserved, we analyzed regenerative cardiomyocyte proliferation after Hdac1 inhibition at the wound border zone in cryoinjured adult zebrafish hearts and we found that Hdac1 is also essential to orchestrate regenerative cardiomyocyte proliferation in the adult vertebrate heart. In summary, our findings suggest an important and conserved role of Histone deacetylase 1 (Hdac1) in developmental and adult regenerative cardiomyocyte proliferation in the vertebrate heart.

Heart disease is one of the most common causes of death in all developed countries. While zebrafish cardiomyocytes are able to proliferate throughout adulthood, mammalian cardiomyocytes lose this ability during early development, and therefore are not capable to replace and renew cardiomyocytes after injury. The underlying mechanisms of cardiomyocyte proliferation are still not completely resolved. Understanding how zebrafish cardiomyocytes preserve their proliferating state, would be a valuable information to foster cardiac regeneration, e.g. after myocardial infarction in patients. Knowledge of the signaling pathways that need to be activated, or deactivated in order to induce cardiomyocyte proliferation after acute or chronic injury will pave the way for the development of genetic and/or pharmacological treatment options. In an ENU-mutagenesis screen, we identified the zebrafish mutant baldrian, which shows reduced embryonic cardiomyocyte proliferation. As genetic cause of the observed phenotype, we identified a missense mutation in the hdac1 gene. By treatment of heart-injured adult fish with the HDAC1 inhibitor Mocetinostat, we were able to show a reduced rate of cardiomyocyte proliferation also in the adult zebrafish heart in vivo, suggesting a role of Hdac1 in embryonic heart growth and adult regenerative cardiomyocyte proliferation in zebrafish.

Single-cell analysis uncovers that metabolic reprogramming by ErbB2 signaling is essential for cardiomyocyte proliferation in the regenerating heart

While the heart regenerates poorly in mammals, efficient heart regeneration occurs in zebrafish. Studies in zebrafish have resulted in a model in which preexisting cardiomyocytes dedifferentiate and reinitiate proliferation to replace the lost myocardium. To identify which processes occur in proliferating cardiomyocytes we have used a single-cell RNA-sequencing approach. We uncovered that proliferating border zone cardiomyocytes have very distinct transcriptomes compared to the nonproliferating remote cardiomyocytes and that they resemble embryonic cardiomyocytes. Moreover, these cells have reduced expression of mitochondrial genes and reduced mitochondrial activity, while glycolysis gene expression and glucose uptake are increased, indicative for metabolic reprogramming. Furthermore, we find that the metabolic reprogramming of border zone cardiomyocytes is induced by Nrg1/ErbB2 signaling and is important for their proliferation. This mechanism is conserved in murine hearts in which cardiomyocyte proliferation is induced by activating ErbB2 signaling. Together these results demonstrate that glycolysis regulates cardiomyocyte proliferation during heart regeneration.

Heart attacks are a common cause of death in the Western world. During a heart attack, oxygen levels in the affected part of the heart decrease, which causes heart muscle cells to die. In humans the dead cells are replaced by a permanent scar that stabilizes the injury but does not completely heal it. As a result, individuals have a lower quality of life after a heart attack and are more likely to die from a subsequent attack.

Unlike humans, zebrafish are able to regenerate their hearts after injury: heart muscle cells close to a wound divide to produce new cells that slowly replace the scar tissue and restore normal function to the area. It remains unclear, however, what stimulates the heart muscle cells of zebrafish to start dividing. To address this question, Honkoop, de Bakker et al. used a technique called single-cell sequencing to study heart muscle cells in wounded zebrafish hearts.

The experiments identified a group of heart muscle cells close to the site of the wound that multiplied to repair the damage. This group of cells had altered their metabolism compared to other heart muscle cells so that they relied on a pathway called glycolysis to produce the energy and building blocks they needed to proliferate. Blocking glycolysis impaired the ability of the heart muscle cells to divide, indicating that this switch is necessary for the heart to regenerate. Further experiments showed that a signaling cascade, which includes the molecules Nrg1 and ErbB2, induces heart muscle cells in both zebrafish and mouse hearts to switch to glycolysis and undergo division.

These findings indicate that activating glycolysis in heart muscle cells may help to stimulate the heart to regenerate after a heart attack or other injury. The next step following on from this work is to develop methods to activate glycolysis and promote cell division in injured hearts.

FEC 60 adjuvant chemotherapy (AdCT) in breast cancer (BC) patients (Pts): 10-year follow-up results

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Background: To evaluate the efficacy of the Epirubicin as a part of the FEC60 AdCT in operable BrC patients in a Brazilian single-center. Methods: We verified retrospectively our experience with FEC 60 as AdCT in pre and postmenopausal, node positive and negative, pathologic stage I, II and III patients with BrC. Pts were submitted after surgery to receive Fluorouracil 600 mg/m2, Epirubicin 60 mg/m2 and Cyclophosphamide 600 mg/m2 every 28 days for 6 cycles. Pts who were ER+ and/or PR+ received Tamoxifen (TMX) 20 mg/day for 5 years after AdCT. Radiotherapy was also offered at the end of AdCT if indicated. All patients were evaluated in terms of 10 year (y) Disease Free Survival (DFS) and Overall Survival (OS). The most common toxicities (acute and chronic) and metastatic sites will also be reported. Results: Between July 1983 and December 1995 a total of 752 patients (ranging from 22 to 77 years old - median 47.7) were encountered and all of them were evaluated to 10 year (y) DFS and OS. Approximately 61% of these patients received adjuvant TMX. Pts in premenopausal and postmenopausal represented 62.5% and 37.5% respectively. 72 (11%) pts had pathological stage I; 353 (46%) pts had stage II and 327 (43%) had stage III. The 10y DFS was 70%, 46% and 19% for stage I, II and III respectively. The 10y OS after a minimal follow-up of 122.98 months was 74%, 48% and 20% for stage I, II and III respectively. Conclusions: Our results demonstrated that FEC 60 regimen is active and well tolerated in the adjuvant treatment for BrC pts. We had about 89% of stage II and III pts and in this population FEC60 regimen add benefit. Nevertheless, the randomized studies indicate that the greatest anticancer effect of Epirubicin requires doses ranging from 75 to 120 mg/m2, but due to economic reasons (we integrate the brazilian public healthy system) we could not offer dosages greater than 60 mg/m2. FEC 60 was feasible and offered reasonable results in our population in terms of 10y DFS and OS.

No significant financial relationships to disclose.

Global models for moving contact lines

We consider thin film flows driven by surface tension and gravity. Within the framework of the lubrication approximation, we study the contact line motion using global models where either precursor film or slip are allowed. We show that completely wetting films can be simulated under both conditions without requiring direct tracking of the contact line interface. We perform a comparative study of standard and positivity preserving numerical methods for these problems in one space dimension, with the ultimate goal of choosing the best method applicable to two-dimensional problems. We find a considerable computational advantage of the precursor film model over the slipping models.

[Tridimensional ultrasonography in andrology]

Three-dimensional ultrasound has already been employed to improve detection and characterization of the masses in various organs. The system can also be expected to improve qualitative evaluation of vessel pathology. Three-dimensional ultrasound could offer an additional contribution even in Andrology, in at least three fields: in the best evaluation of the anatomical structures; in most accurate measurement of the volumes of the organs; in the study of the Peyronie's disease, for the availability of the coronal plain.