Effects of antenatal glucocorticoid therapy on hippocampal histology of preterm infants

Objective

To investigate if antenatal glucocorticoid treatment has an effect on hippocampal histology of the human preterm newborn.

Patients and Methods

Included were consecutive neonates with a gestational age between 24 and 32 weeks, who were born between 1991 to 2009, who had died within 4 days after delivery and underwent brain autopsy. Excluded were neonates with congenital malformations and neonates treated postnatally with glucocorticoids.The brains were routinely fixed, samples of the hippocampus were stained with haematoxylin and eosin and sections were examined for presence or absence of large and small neurons in regions of the hippocampus. Additional staining with GFAP, neurofilament and vimentin was performed to evaluate gliosis and myelination. The proliferation marker Ki67 was used to evaluate neuronal proliferation. Staining with acid fuchsin-thionin was performed to evaluate ischemic damage.

Results

The hippocampi of ten neonates who had been treated with antenatal glucocorticoids showed a lower density of large neurons (p = 0.01) and neurons irrespective of size (p = 0.02) as compared to eleven neonates who had not been treated with glucocorticoids. No difference was found in density of small neurons, in myelination, gliosis, proliferation or ischemic damage.

Conclusion

We found a significantly lower density of neurons in the hippocampus of neonates after antenatal glucocorticoid treatment. Although the pathophysiological and clinical interpretations of these findings are not clear, they are consistent with those from experiments in mice and rhesus monkeys.     

Mitochondrial rhomboid PARL regulates cytochrome c release during apoptosis via OPA1-dependent cristae remodeling

Rhomboids, evolutionarily conserved integral membrane proteases, participate in crucial signaling pathways. Presenilin-associated rhomboid-like (PARL) is an inner mitochondrial membrane rhomboid of unknown function, whose yeast ortholog is involved in mitochondrial fusion. Parl-/- mice display normal intrauterine development but from the fourth postnatal week undergo progressive multisystemic atrophy leading to cachectic death. Atrophy is sustained by increased apoptosis, both in and ex vivo. Parl-/- cells display normal mitochondrial morphology and function but are no longer protected against intrinsic apoptotic death stimuli by the dynamin-related mitochondrial protein OPA1. Parl-/- mitochondria display reduced levels of a soluble, intermembrane space (IMS) form of OPA1, and OPA1 specifically targeted to IMS complements Parl-/- cells, substantiating the importance of PARL in OPA1 processing. Parl-/- mitochondria undergo faster apoptotic cristae remodeling and cytochrome c release. These findings implicate regulated intramembrane proteolysis in controlling apoptosis.     

Mathematical Models for Sleep-Wake Dynamics: Comparison of the Two-Process Model and a Mutual Inhibition Neuronal Model

Sleep is essential for the maintenance of the brain and the body, yet many features of sleep are poorly understood and mathematical models are an important tool for probing proposed biological mechanisms. The most well-known mathematical model of sleep regulation, the two-process model, models the sleep-wake cycle by two oscillators: a circadian oscillator and a homeostatic oscillator. An alternative, more recent, model considers the mutual inhibition of sleep promoting neurons and the ascending arousal system regulated by homeostatic and circadian processes. Here we show there are fundamental similarities between these two models. The implications are illustrated with two important sleep-wake phenomena. Firstly, we show that in the two-process model, transitions between different numbers of daily sleep episodes can be classified as grazing bifurcations. This provides the theoretical underpinning for numerical results showing that the sleep patterns of many mammals can be explained by the mutual inhibition model. Secondly, we show that when sleep deprivation disrupts the sleep-wake cycle, ostensibly different measures of sleepiness in the two models are closely related. The demonstration of the mathematical similarities of the two models is valuable because not only does it allow some features of the two-process model to be interpreted physiologically but it also means that knowledge gained from study of the two-process model can be used to inform understanding of the behaviour of the mutual inhibition model. This is important because the mutual inhibition model and its extensions are increasingly being used as a tool to understand a diverse range of sleep-wake phenomena such as the design of optimal shift-patterns, yet the values it uses for parameters associated with the circadian and homeostatic processes are very different from those that have been experimentally measured in the context of the two-process model.     

Organelle analysis of symmetric and asymmetric hybrids between Lycopersicon peruvianum and Lycopersicon esculentum

Summary The organelles of somatic hybrids obtained from symmetric and asymmetric fusions between the Lycopersicon species L. peruvianum and L. esculentum were analyzed by DNA hybridization methods. In the asymmetric fusions the L. peruvianum protoplasts were gamma-irradiated at a dose of 50, 300 and 1,000 Gy. The organelles were characterized using the Petunia chloroplast probe pPCY64 and the mitochondrial EcoRI-SalI fragment of the Pcf gene. In all symmetric and asymmetric hybrid plants, a total of 73 being analyzed, only one of the parental chloroplast genomes was present, except for one hybrid plant which harbored both parental chloroplast genomes. No recombination and/or rearrangement in the chloroplast genome could be identified with the pPCY64 probe. Irradiation of the L. peruvianum protoplasts did not significantly reduce the fraction of asymmetric hybrids with L. peruvianum chloroplasts. A novel mitochondrial restriction pattern was present in 5 out of 24 hybrids tested. In 9 hybrids novel combinations of chloroplasts and mitochondria were found, indicating that both organelle types sorted out independently.     

Interaction of monovalent cations with Rb+ and Na+ uptake in yeast

The concentration dependence of both Rb⁺ uptake and Na⁺ uptake by yeast can be described by a quadratic rate equation. This equation is derived for translocation of cations via a two-site translocation system. In accordance with predictions made for such a two-site translocation system the shape of the uptake isotherm depends both upon the substrate cation species and upon the concentration of other added competing cations. On plotting the rate of Rb⁺ uptake against the quotient of that rate and the Rb⁺ concentration concave, convex and also linear curves are found depending upon the type and the concentration of added monovalent cations. The Na⁺ uptake isotherm plotted in a similar way shows a shift from a concave curve to a straight line on adding increasing amounts of Rb⁺ to the yeast suspension.Decreasing the pH of the medium leads to a more pronounced convex     

Association between public media and trends in new acute coronary syndrome presentations during the first COVID‑19 wave in the Netherlands

BackgroundWe aimed to evaluate the association between public media and trends in new presentations of acute coronary syndrome (ACS) during the first wave of the coronavirus disease 2019 (COVID‑19) in the Netherlands.MethodsNew ACS presentations per week in 73 hospitals during the first half of 2019 and 2020 were retrieved from the national organisation Dutch Hospital Data and incidence rates were calculated. Stratified analyses were performed by region, type of ACS and patient characteristics.ResultsAfter the first confirmed COVID‑19 case and during lockdown, numbers declined by up to 41% (95% confidence interval (CI): 36–47%) compared to 2019. This reduction was more pronounced for non-ST-segment elevation myocardial infarction (NSTEMI) (48%; 95% CI: 39–55%) and unstable angina (UA; 50%; 95% CI: 40–59%) than for STEMI (34%; 95% CI: 23–43%). There was no association between ACS and COVID‑19 incidence rate per region. After the steep decline, a public campaign encouraged patients not to postpone hospital visits. Numbers then increased, without a rebound effect. Trends were similar irrespective of sex, age or socio-economic status. During the outbreak, compared to coronary artery bypass graft procedures, relatively more (acute) percutaneous coronary interventions for NSTEMI and UA were performed.ConclusionNew ACS presentations decreased by up to 41%. Lockdown measures and public campaigns, rather than COVID‑19 incidence, were associated with significant changes in new ACS presentations. Even though causality cannot be established, this emphasises the role of the public media and healthcare organisations in informing patients to prevent underdiagnoses of ACS and associated health damage.Supplementary InformationThe online version of this article (10.1007/s12471-021-01603-5) contains supplementary material, which is available to authorized users.     

Identification of single-point mutations in mycobacterial 16S rRNA sequences by confocal single-molecule fluorescence spectroscopy

We demonstrate the specific identification of single nucleotide polymorphism (SNP) responsible for rifampicin resistance of Mycobacterium tuberculosis applying fluorescently labeled DNA-hairpin structures (smart probes) in combination with single-molecule fluorescence spectroscopy. Smart probes are singly labeled hairpin-shaped oligonucleotides bearing a fluorescent dye at the 5′ end that is quenched by guanosine residues in the complementary stem. Upon hybridization to target sequences, a conformational change occurs, reflected in a strong increase in fluorescence intensity. An excess of unlabeled (‘cold’) oligonucleotides was used to prevent the formation of secondary structures in the target sequence and thus facilitates hybridization of smart probes. Applying standard ensemble fluorescence spectroscopy we demonstrate the identification of SNPs in PCR amplicons of mycobacterial rpoB gene fragments with a detection sensitivity of 10⁻⁸ M. To increase the detection sensitivity, confocal fluorescence microscopy was used to observe fluorescence bursts of individual smart probes freely diffusing through the detection volume. By measuring burst size, burst duration and fluorescence lifetime for each fluorescence burst the discrimination accuracy between closed and open (hybridized) smart probes could be substantially increased. The developed technique enables the identification of SNPs in 10⁻¹¹ M solutions of PCR amplicons from M.tuberculosis in only 100 s.     

Regulated intramembrane proteolysis of amyloid precursor protein and regulation of expression of putative target genes

gamma-Secretase-dependent regulated intramembrane proteolysis of amyloid precursor protein (APP) releases the APP intracellular domain (AICD). The question of whether this domain, like the Notch intracellular domain, is involved in nuclear signalling is highly controversial. Although some reports suggest that AICD regulates the expression of KAI1, glycogen synthase kinase-3beta, Neprilysin and APP, we found no consistent effects of gamma-secretase inhibitors or of genetic deficiencies in the gamma-secretase complex or the APP family on the expression levels of these genes in cells and tissues. Finally, we demonstrate that Fe65, an important AICD-binding protein, transactivates a wide variety of different promoters, including the viral simian virus 40 promoter, independent of AICD coexpression. Overall, the four currently proposed target genes are at best indirectly and weakly influenced by APP processing. Therefore, inhibition of APP processing to decrease Abeta generation in Alzheimer's disease will not interfere significantly with the function of these genes.