Pediatric transplantation in Europe during the COVID-19 pandemic: Early impact on activity and healthcare

The current pandemic SARS-CoV-2 has required an unusual allocation of resources that can negatively impact chronically ill patients and high-complexity procedures. Across the European Reference Network on Pediatric Transplantation (ERN TransplantChild), we conducted a survey to investigate the impact of the COVID-19 outbreak on pediatric transplant activity and healthcare practices in both solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT). The replies of 30 professionals from 18 centers in Europe were collected. Twelve of 18 centers (67%) showed a reduction in their usual transplant activity. Additionally, outpatient visits have been modified and restricted to selected ones, and the use of telemedicine tools has increased. Additionally, a total of 14 COVID-19 pediatric transplanted patients were identified at the time of the survey, including eight transplant recipients and six candidates for transplantation. Only two moderate-severe cases were reported, both in HSCT setting. These survey results demonstrate the limitations in healthcare resources for pediatric transplantation patients during early stages of this pandemic. COVID-19 disease is a major worldwide challenge for the field of pediatric transplantation, where there will be a need for systematic data collection, encouraging regular discussions to address the long-term consequences for pediatric transplantation candidates, recipients, and their families.     

Effects of ponesimod,a selective S1P1 receptor modulator,on the pharmacokinetics of a hormonal combination contraceptive

Purpose

To determine the effects of steady-state concentrations of the selective S1P₁ receptor modulator ponesimod on the pharmacokinetics (PK) of a single dose of a combined oral contraceptive, containing 1 mg norethisterone (NET) and 35 μg ethinyl estradiol (EE) and to investigate the effects on heart rate at different ponesimod doses within an up-titration regimen prior to co-administration of the contraceptive.

Methods

Twenty-two healthy women (age: 29-60 years) received twice a single oral dose of the combined oral contraceptive, alone or in combination with multiple doses of 40 mg ponesimod attained by an up-titration regimen. Heart rate (HR) effects were assessed on the first day of each up-titration level. PK parameters of NET and EE were determined by non-compartmental analysis.

Results

Geometric mean ratios (ponesimod and contraceptive / contraceptive alone) of C_max and AUC_0-24 of NET were 0.87 (90 % CI: 0.80, 0.94) and 0.84 (90 % CI: 0.76, 0.93), respectively. Geometric mean ratios of C_max and AUC_0-24 of EE were 0.94 (90 % CI: 0.86, 1.03) and 0.95 (90 % CI: 0.89, 1.01), respectively. The maximum mean HR reduction after the first dose of 10 mg ponesimod was 12.4 bpm (SD?±?6.2) at 2.5 h post-dose. On Day 4 (first dose of 20 mg) and Day 7 (first dose of 40 mg) the maximum mean HR reduction was 4.3 bpm (SD?±?5.7) and 1.4 (SD?±?6.4), respectively, at 2.5 h post-dose compared to baseline.

Conclusion

No clinically relevant PK interactions between ponesimod and the combined oral contraceptive were observed, therefore, efficacy of hormonal contraceptives is not expected to be affected by concomitant administration of ponesimod. The up-titration regimen showed that HR reductions are diminished upon repeated ponesimod administration.     

Prevalence,Trends, and Outcomes of Higher-Risk Percutaneous Coronary Interventions Among Patients Without Acute Coronary Syndromes

Background/purpose

Patients and lesions at a higher procedural risk for percutaneous coronary intervention (PCI) are an understudied population. We examined the frequency, clinical characteristics, and outcomes of higher risk and non-higher risk PCIs at a large tertiary center.

Genome-wide RNA interference screen identifies previously undescribed regulators of polyglutamine aggregation

Protein misfolding and the formation of aggregates are increasingly recognized components of the pathology of human genetic disease and hallmarks of many neurodegenerative disorders. As exemplified by polyglutamine diseases, the propensity for protein misfolding is associated with the length of polyglutamine expansions and age-dependent changes in protein-folding homeostasis, suggesting a critical role for a protein homeostatic buffer. To identify the complement of protein factors that protects cells against the formation of protein aggregates, we tested transgenic Caenorhabditis elegans strains expressing polyglutamine expansion yellow fluorescent protein fusion proteins at the threshold length associated with the age-dependent appearance of protein aggregation. We used genome-wide RNA interference to identify genes that, when suppressed, resulted in the premature appearance of protein aggregates. Our screen identified 186 genes corresponding to five principal classes of polyglutamine regulators: genes involved in RNA metabolism, protein synthesis, protein folding, and protein degradation; and those involved in protein trafficking. We propose that each of these classes represents a molecular machine collectively comprising the protein homeostatic buffer that responds to the expression of damaged proteins to prevent their misfolding and aggregation.     

Plasmin activity is required for myogenesis in vitro and skeletal muscle regeneration in vivo

Plasmin, the primary fibrinolytic enzyme, has a broad substrate spectrum and is implicated in biologic processes dependent upon proteolytic activity, such as tissue remodeling and cell migration. Active plasmin is generated from proteolytic cleavage of the zymogen plasminogen (Plg) by urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA). Here, we have investigated the role of plasmin in C2C12 myoblast fusion and differentiation in vitro, as well as in skeletal muscle regeneration in vivo, in wild-type and Plg-deficient mice. Wild-type mice completely repaired experimentally damaged skeletal muscle. In contrast, Plg(-/-) mice presented a severe regeneration defect with decreased recruitment of blood-derived monocytes and lymphocytes to the site of injury and persistent myotube degeneration. In addition, Plg-deficient mice accumulated fibrin in the degenerating muscle fibers; however, fibrinogen depletion of Plg-deficient mice resulted in a correction of the muscular regeneration defect. Because we found that uPA, but not tPA, was induced in skeletal muscle regeneration, and persistent fibrin deposition was also reproducible in uPA-deficient mice following injury, we propose that fibrinolysis by uPA-dependent plasmin activity plays a fundamental role in skeletal muscle regeneration. In summary, we identify plasmin as a critical component of the mammalian skeletal muscle regeneration process, possibly by preventing intramuscular fibrin accumulation and by contributing to the adequate inflammatory response after injury. Finally, we found that inhibition of plasmin activity with alpha2-antiplasmin resulted in decreased myoblast fusion and differentiation in vitro. Altogether, these studies demonstrate the requirement of plasmin during myogenesis in vitro and muscle regeneration in vivo.     

Effect of 3'' flanking neighbors on kinetics of pairing of dCTP or dTTP opposite O6-methylguanine in a defined primed oligonucleotide when Escherichia coli DNA polymerase I is used.

O6-Methylguanine (m6G) was incorporated site-specifically into two 25-base oligonucleotides differing only in the nucleotide on the 3' side of the modified base. Templates were primed with oligonucleotides terminating one or two bases prior to the site at which incorporation kinetics were to be investigated. Escherichia coli DNA polymerase I (Klenow fragment) was used to determine the apparent Km and relative Vmax of incorporation of either dCTP or dTTP opposite m6G or G. These data were used to calculate the relative frequency of incorporation opposite the m6G or the unmodified G. When the sequence was 3'-Cm6G-5', there was a 6- to 7-fold preference for formation of a m6G.T pair compared with m6G.C. The m6G.T frequency, based on Vmax/Km, was at least 50-fold greater than that of a G.T pair at the same site. Changing the sequence to 3'-Tm6G-5' had a marked effect on both Km and Vmax of pairs containing m6G and on the incorporation frequency of T opposite m6G, which was then only slightly favored over m6G.C. When replication was started directly opposite m6G, the kinetics appeared unaffected. These data indicate that the frequency of incorporation of C or T opposite m6G in a DNA template is dependent on the flanking neighbors and that a change of even a single base at the 3' position can have a major effect on mutagenic efficiency. Replication using Drosophila Pol alpha gave the same values for relative frequencies. Pairing of either C or T with m6G on the primer terminus did not significantly inhibit extension of the next normal base pair, in contrast to terminal mismatches of unmodified bases. It is concluded that, in the absence of repair, m6G can exhibit widely differing mutation frequencies which, in these experiments, can be as high as 85% of the replicated base. This variation in frequency of changed pairing could contribute to the occurrence of mutational "'hot spots" after replication of damaged DNA.