Hormonal regulation of cell junction permeability: Upregulation by catecholamine and prostaglandin E1

Summary By cellular activation with hormones, we test the proposition (Loewenstein, W.R.,Physiol. Rev. 61:829, 1981) that the permeability of cell junction is upregulated through elevation of the level of cyclic AMP. Cultured rat glioma C-6 cells, with -adrenergic receptors, and human lung WI-38 cells, with prostaglandin receptors, were exposed to catecholamine (isoproterenol) and prostaglandin E₁, respectively, while their junctions were probed with microinjected fluorescent-labelled mono-, di-, and triglutamate. Junctional permeability, as indexed by the proportion of cell interfaces transferring the probes, rose after the hormone treatments. The increase in permeability took several hours to develop and was associated with an increase in the number of gap-junctional membrane particles (freeze-fracture electron microscopy). Such interaction between hormonal and junctional intercellular communication may provide a mechanism for physiological regulation of junctional communication and (perhaps as part of that) for physiological coordination of responses of cells in organs and tissues to hormones.     

Kinetics and persistence of cellular and humoral immune responses to SARS‐CoV‐2 vaccine in healthcare workers with or without prior COVID‐19

SARS‐CoV‐2 vaccines are highly efficient against severe forms of the disease, hospitalization and death. Nevertheless, insufficient protection against several circulating viral variants might suggest waning immunity and the need for an additional vaccine dose. We conducted a longitudinal study on the kinetics and persistence of immune responses in healthcare workers vaccinated with two doses of BNT162b2 mRNA vaccine with or without prior SARS‐CoV‐2 infection. No new infections were diagnosed during follow‐up. At 6 months, post‐vaccination or post‐infection, despite a downward trend in the level of anti‐S IgG antibodies, the neutralizing activity does not decrease significantly, remaining higher than 75% (85.14% for subjects with natural infection, 88.82% for vaccinated after prior infection and 78.37% for vaccinated only). In a live‐virus neutralization assay, the highest neutralization titres were present at baseline and at 6 months follow‐up in persons vaccinated after prior infection. Anti‐S IgA levels showed a significant descending trend in vaccinated subjects (p < 0.05) after 14 weeks. Cellular immune responses are present even in vaccinated participants with declining antibody levels (index ratio 1.1–3) or low neutralizing activity (30%–40%) at 6 months, although with lower T‐cell stimulation index (p = 0.046) and IFN‐γ secretion (p = 0.0007) compared to those with preserved humoral responses.     

The connective connection: interstitial cells of Cajal (ICC) and ICC-like cells establish synapses with immunoreactive cells. Electron microscope study in situ

We present transmission electron microscope (TEM) evidence that ICC and ICC-like cells frequently establish close contacts (synapses) with several types of immunoreactive cells (IRC): lymphocytes, plasma cells, eosinophils, basophils, macrophages and mast cells. Such synapses were found in various organs: human mammary gland and myometrium, as well as rat stomach, gut, bladder and uterus. Specimens were observed by conventional TEM on ultrathin sections. Based on morphometric analyses and computer-aided 3-D reconstructions from serial sections, we propose an operational definition of ICC-IRC synapses: cell-to-cell close contacts where the two cells are separated by only approximately 15 nm, equivalent to twice the plasmalemmal thickness. Two types of such synapses were found: (i) uniform ('plain') synapses (PS). close contact extending for >200 nm, and (ii) multi-contact ('kiss and run') synapses (MS)--with multiple, focal, close-contact points alternating with regions of wider intermembrane distance. For instance, a typical PS between a rat bladder ICC-like cell and an eosinophil was 2.48 microm long and 11+/-4 nm wide. By contrast, a MS synapse in rat myometrium (between an ICC-like cell and an eosinophil) was 8.64 microm long and had 13 contact points. The synaptic cleft measured 15+/-8 nm at contact points and approximately 100 nm or more in wider areas. These synapses are different from gap junctions usually seen between ICC and between ICC and smooth muscle cells. We previously proposed that ICC-like cells might represent stromal progenitor cells, participate in juxtacrine/paracrine signaling and play a role in immune surveillance. The nanoscopic distances between the two contiguous membranes suggest a juxtacrine cell-to-cell signaling (chemical synapse), via juxtacrinins, a specific case of phenomenins. However, the (micro)vesicles found in the synaptic cleft may correspond to an exosome-based mechanism.     

Improvement in raw sago starch degrading enzyme production from Acremonium sp. endophytic fungus using carbon and nitrogen sources

Attempts were made to improve the growth of endophytic fungus Acremonium sp. and its raw sago starch degrading enzyme (RSSDE) production using different nitrogen and carbon sources at varying pH values and temperatures. It was observed that growth and enzyme activity levels were highest with peptone and sodium nitrate as the nitrogen sources and raw sago starch as the carbon source of which the optimum concentrations were 0.5 g/l, 3 g/l, and 20 g/l, respectively. Cell growth and RSSDE production reached their optimum at pH 5.0 and incubation temperature of 30 degrees C. Under these conditions, the enzyme production was significantly increased by 19- to 22-folds compared to the activity obtained in the original basal medium.     

PTPsigma promotes retinal neurite outgrowth non-cell-autonomously

The receptor-like protein tyrosine phosphatase (RPTP) PTPsigma controls the growth and targeting of retinal axons, both in culture and in ovo. Although the principal actions of PTPsigma have been thought to be cell-autonomous, the possibility that RPTPs related to PTPsigma also have non-cell-autonomous signaling functions during axon development has also been supported genetically. Here we report that a cell culture substrate made from purified PTPsigma ectodomains supports retinal neurite outgrowth in cell culture. We show that a receptor for PTPsigma must exist on retinal axons and that binding of PTPsigma to this receptor does not require the known, heparin binding properties of PTPsigma. The neurite-promoting potential of PTPsigma ectodomains requires a basic amino acid domain, previously demonstrated in vitro as being necessary for ligand binding by PTPsigma. Furthermore, we demonstrate that heparin and oligosaccharide derivatives as short as 8mers, can specifically block neurite outgrowth on the PTPsigma substrate, by competing for binding to this same domain. This is the first direct evidence of a non-cell-autonomous, neurite-promoting function of PTPsigma and of a potential role for heparin-related oligosaccharides in modulating neurite promotion by an RPTP.     

Novel progerin-interactive partner proteins hnRNP E1, EGF, Mel 18, and UBC9 interact with lamin A/C

The Hutchinson-Gilford progeria syndrome (HGPS or progeria) is an apparent accelerated aging disorder of childhood. Recently, HGPS has been characterized as one of a growing group of disorders known as laminopathies, which result from genetic defects of the lamin A/C (LMNA) gene. The majority of HGPS mutant alleles involve a silent mutation, c.2063C>T resulting in G608G, that generates a cryptic splicing site in exon 11 of LMNA and consequently truncates 50 amino acids near the C-terminus of pre-lamin A/C. To explore possible mechanisms underlying the development of HGPS, we began a search for proteins that would uniquely interact with progerin (the truncated lamin A in HGPS) using a yeast two-hybrid system. Four new progerin interactive partner proteins were identified that had not been previously found to interact with lamin A/C: hnRNP E1, UBC9 (ubiquitin conjugating enzyme E2I), Mel-18, and EGF1. However, using control and progeria fibroblasts, co-immunoprecipitation studies of endogenous proteins did not show differential binding affinity compared to normal lamin A/C. Thus, we did not find evidence for uniquely interacting partner proteins using this approach, but did identify four new lamin A/C interactive partners.     

High-resolution crystal structures of Desulfovibrio vulgaris (Hildenborough) nigerythrin: facile, redox-dependent iron movement, domain interface variability, and peroxidase activity in the rubrerythrins

High-resolution crystal structures of Desulfovibrio vulgaris nigerythrin (DvNgr), a member of the rubrerythrin (Rbr) family, demonstrate an approximately 2-Å movement of one iron (Fe1) of the diiron site from a carboxylate to a histidine ligand upon conversion of the mixed-valent ([Fe2(II),Fe1(III)]) to diferrous states, even at cryogenic temperatures. This GluHis ligand toggling of one iron, which also occurs in DvRbr, thus, appears to be a characteristic feature of Rbr-type diiron sites. Unique features of DvNgr revealed by these structures include redox-induced flipping of a peptide carbonyl that reversibly forms a hydrogen bond to the histidine ligand to Fe1 of the diiron site, an intra-subunit proximal orientation of the rubredoxin-(Rub)-like and diiron domains, and an electron transfer pathway consisting of six covalent and two hydrogen bonds connecting the Rub-like iron with Fe2 of the diiron site. This pathway can account for DvNgrs relatively rapid peroxidase turnover. The characteristic combination of iron sites together with the redox-dependent iron toggling between protein ligands can account for the selectivity of Rbrs for hydrogen peroxide over dioxygen.Electronic Supplementary Material Supplementary material is available for this article at .An erratum to this article can be found at Ramesh B. Iyer and Radu Silaghi-Dumitrescu contributed equally to this work.     

Nocturnal acid breakthrough - approach to management

Nocturnal acid breakthrough is defined as the presence of intragastric pH < 4 during the overnight period for at least 60 continuous minutes in patients taking a proton-pump inhibitor (PPI). Nocturnal acid breakthrough occurs in more than 70% of Helicobacter pylori-negative patients on PPI therapy and has clinical consequences in particular in patients with complicated gastroesophageal reflux disease (GERD), Barrett's esophagus, and esophageal motility abnormalities. The clinical importance of nocturnal acid breakthrough and the benefit of adding histamine-2 receptor antagonists (H2RAs) to PPI therapy have been debated ever since these concepts were introduced. In our experience, the addition of bedtime H2RAs is clinically effective in controlling nocturnal acid breakthrough and GERD symptoms.     

Maintenance of size and function of influenza virus hemagglutinin specific transgenic T-cell clone during life

Immunization induces less protective immunity against infectious diseases in old compared to young subjects. We have studied the effect of age on the in vitro and in vivo function of murine transgenic T cells expressing a receptor for influenza hemagglutinin 110-120 peptide. During aging the transgenic T cells undergo the age-associated shift from naive to memory phenotype but maintain, despite thymic involution, their number as well as their cytokine production and proliferative responses induced by the hemagglutinin 110-120 peptide in vitro . The maintenance of the size and functions of transgenic T cells during the aging may be related to low expression of CTLA-4 molecules known to exhibit a negative regulatory effect subsequent to interaction with costimulatory molecules as well as of stimulation of T cells by unknown cross reactive endogenous factors but not by nominal antigen since innate immunity prevents natural infection with influenza virus of murine species. This suggests that the impaired immunity induced by immunization in old subjects reflects defects in the development and maintenance of T cell memory and not in the expression of effector activity.