Constitutional and mosaic large NF1 gene deletions in neurofibromatosis type 1.

A set of neurofibromatosis type 1 (NF1) patients was screened for large NF1 gene deletions by comparing patient and parent genotypes at 10 intragenic polymorphic loci. Of 67 patient/parent sets (47 new mutation patients and 20 familial cases), five (7.5%) showed loss of heterozygosity (LOH), indicative of NF1 gene deletion. These five patients did not have severe NF1 manifestations, mental retardation, or dysmorphic features, in contrast to previous reports of large NF1 deletions. All five deletions were de novo and occurred on the maternal chromosome. However, two patients showed partial LOH, consistent with somatic mosaicism for the deletion, suggesting that mosaicism may be more frequent in NF1 than previously recognised (and may have bearing on clinical severity). We suggest that large NF1 deletions (1) are not always associated with unusual clinical features, (2) tend to occur more frequently on maternal alleles, and (3) are an important mechanism for constitutional and somatic mutations in NF1 patients.     

A bovine aortic arch in humans

We describe a curious congenital variation of human aortic arch (AA) branching pattern termed the “bovine aortic arch”. Rather than arising directly from the AA as a separate branch as occurs in the most common AA branching pattern, the left common carotid artery moves to the right and merges from the brachiocephalic trunk. It is the normal AA branching pattern presented in a number of animals (canines, felines or Macaque monkeys) but it has nothing to do with anatomy of AA in ruminant animals, including cattle and buffalo. That is why it is one of the most widely misnomers used in medical literature whose origin is nowadays unknown.     

Thioredoxin-related protein of 14 kDa is an efficient L-cystine reductase and S-denitrosylase

Thioredoxin-related protein of 14 kDa (TRP14, also called TXNDC17 for thioredoxin domain containing 17, or TXNL5 for thioredoxin-like 5) is an evolutionarily well-conserved member of the thioredoxin (Trx)-fold protein family that lacks activity with classical Trx1 substrates. However, we discovered here that human TRP14 has a high enzymatic activity in reduction of l-cystine, where the catalytic efficiency (2,217 min⁻¹⋅µM⁻¹) coupled to Trx reductase 1 (TrxR1) using NADPH was fivefold higher compared with Trx1 (418 min⁻¹⋅µM⁻¹). Moreover, the l-cystine reduction with TRP14 was in contrast to that of Trx1 fully maintained in the presence of a protein disulfide substrate of Trx1 such as insulin, suggesting that TRP14 is a more dedicated l-cystine reductase compared with Trx1. We also found that TRP14 is an efficient S-denitrosylase with similar efficiency as Trx1 in catalyzing TrxR1-dependent denitrosylation of S-nitrosylated glutathione or of HEK293 cell-derived S-nitrosoproteins. Consequently, nitrosylated and thereby inactivated caspase 3 or cathepsin B could be reactivated through either Trx1- or TRP14-catalyzed denitrosylation reactions. TRP14 was also, in contrast to Trx1, completely resistant to inactivation by high concentrations of hydrogen peroxide. The oxidoreductase activities of TRP14 thereby complement those of Trx1 and must therefore be considered for the full understanding of enzymatic control of cellular thiols and nitrosothiols.The redox or nitrosylation state of reactive cysteine (Cys) residues in proteins can affect a multitude of intracellular events, either beneficial or harmful, depending upon biological context (1, 2). Two major cellular systems that control the redox states of Cys residues are the thioredoxin (Trx) and the glutathione (GSH) systems. The Trx system includes isoforms of Trx, Trx reductase (TrxR), and NADPH together with several Trx-dependent enzymes and proteins (3). The GSH/GSH disulfide redox couple is kept reduced by the NADPH-dependent activity of GSH reductase (GR) and donates electrons to isoforms of glutaredoxin (Grx) and other GSH-dependent enzymes (4).In addition to Trx, many proteins have a Trx fold and a Trx-like active-site sequence. One such protein is thioredoxin-related protein of 14 kDa (TRP14, also known as TXNDC17 or TXNL5), which is an evolutionarily well-conserved cytosolic and widely expressed Trx-fold protein that can be reduced by TrxR1 (5). Its crystal structure, compared with Trx1, shows additional structural features in the active site, thereby explaining its lack of activity with most classical Trx1 protein disulfide substrates including ribonucleotide reductase, insulin, peroxiredoxins, or methionine sulfoxide reductase (5–7). TRP14 was suggested to have evolved to exert specific signaling roles in cells and was identified as a modulator of TNFα/NFκB signaling pathways through interactions with the dynein light chain LC8 protein (6, 8). We previously found that treatment of cells with cisplatin triggered the formation of covalent cross-links between TrxR1 and either Trx1 or TRP14, which suggests that TRP14 is tightly linked to TrxR1 within the cellular context (9). Recently, we also found that TRP14 is able to reactivate oxidized phosphotyrosine phosphatase 1B, thereby indeed implicating specific functions in modulation of cellular signaling pathways (10).In addition to having general protein disulfide reductase activities, Trx1 is also a denitrosylase for a broad spectrum of nitrosoproteins and nitrosothiols (11, 12). Substrates include S-nitrosocaspase 3 (13, 14), S-nitrosocaspase 8 (15), S-nitrosoglutathione (GSNO) (16, 17), and S-nitrosocysteine (l-CysSNO) (12). Nitrosylation and denitrosylation reactions provide a regulatory mechanism for protein function and are thereby also involved in a variety of cellular signal transduction pathways. For example, S-nitrosylation of caspases can inhibit their activity and thus regulate apoptosis in resting cells (18, 19). A full understanding of NO homeostasis and its pathways is of medical importance because an aberrant formation of nitrosylated proteins has been implicated in a variety of diseases. However, protein denitrosylation is a hitherto less studied part in NO-mediated signaling (20, 21). In addition to Trx1, another enzyme mediating cellular denitrosylation reactions is GSNO reductase (GSNOR). GSNOR is the same enzyme as class III alcohol dehydrogenase, mainly catalyzing denitrosylation of GSNO using NADH as an electron donor (22, 23). In addition, S-denitrosylation activities are supported by protein disulfide isomerase (PDI) (24), carbonyl reductase 1 (25), and lipoic acid (17).The high intracellular concentrations of GSH are also important in NO metabolism because of facilitated formation of GSNO by reaction of GSH with NO or by denitrosylation of cellular nitrosothiols (20, 26). Because the synthesis of GSH depends upon availability, cellular uptake and reduction of sulfur-containing precursors such as l-cystine, l-cystine homeostasis is also important for GSH functions (27). l-Cystine is taken up into cells using different transport systems, e.g., the oxidative stress-inducible cystine/glutamate antiporter (system ) (28). The mechanism behind the reduction of l-cystine still has not been fully elucidated, but has been implicated to include GSH itself or also TrxR1-dependent systems (29).In the present study, we wanted to further characterize the enzymatic properties of TRP14, which revealed that the protein is at least as efficient as Trx1 in supporting reduction of specific redox substrates, such as l-cystine. In that assay, TRP14 is a fivefold better substrate for TrxR1 than Trx1 itself and, furthermore, more dedicated as its activity is not diminished in the presence of other Trx1 substrates that are not reduced by TRP14. Furthermore, we discovered that TRP14 is yet another cytosolic oxidoreductase that can catalyze S-denitrosylation reactions.     

Impacto de la infección por el nuevo coronavirus en los pacientes con uveítis asociada a una enfermedad autoinmune: resultado de la encuesta COVID-19-GEAS pacientes

IntroductionThe objetive of these study is to know the characteristics of COVID-19 in patients with uveitis associated with Systemic Autoimmune Disease (SAD) through telematic survey.Material and methodsInternal Medicine Society and Group of Systemic Autoimmune disease conducted a telematic survey of patients with SAD to learn about the characteristics of COVID-19 in this population.ResultsA total of 2,789 patients answered the survey, of which 28 had a diagnosis of uveitis associated with SAE. The majority (82%) were female and caucasian (82%), with a mean age of 48 years. The most frequent SAEs were Behçet's disease followed by sarcoidosis and systemic lupus erythematosus. 46% of the patients were receiving corticosteroid treatment at a mean prednisone dose of 11 mg/day. Regarding infection, 14 (50%) patients reported symptoms compatible with SARS-CoV-2 infection. RT-PCR was performed on the nasopharyngeal smear in two patients and in one of them (4%) it was positive.ConclusionsBoth asymptomatic and symptomatic COVID-19 patients with ASD-associated UNI had received similar immunosuppressive treatment.     

Adoptive Transfer of Renal Allograft Tolerance in a Large Animal Model

Our recent studies in an inbred swine model demonstrated that both peripheral and intra‐graft regulatory cells were required for the adoptive transfer of tolerance to a second, naïve donor‐matched kidney. Here, we have asked whether both peripheral and intra‐graft regulatory elements are required for adoptive transfer of tolerance when only a long‐term tolerant (LTT) kidney is transplanted. Nine highly‐inbred swine underwent a tolerance‐inducing regimen to prepare LTT kidney grafts which were then transplanted to histocompatible recipients, with or without the peripheral cell populations required for adoptive transfer of tolerance to a naïve kidney. In contrast to our previous studies, tolerance of the LTT kidney transplants alone was achieved without transfer of additional peripheral cells and without strategies to increase the number/potency of regulatory T cells in the donor. This tolerance was systemic, since most subsequent, donor‐matched challenge kidney grafts were accepted. These results confirm the presence of a potent tolerance‐inducing and/or tolerance‐maintaining cell population within LTT renal allografts. They suggest further that additional peripheral tolerance mechanisms, required for adoptive transfer of tolerance to a naïve donor‐matched kidney, depend on peripheral cells that, if not transferred with the LTT kidney, require time to develop in the adoptive host.     

Extreme sports performance for more than a week with severely fractured sleep

Sleep and Breathing - Severely fractured sleep is mostly portrayed negatively, but investigations in extreme sports show that humans can maintain performance with a minimum of sleep. With two cases...