D-Dimer Elevation at Time of Admission is Associated with Need for Ventilator Support among Pediatric Patients with COVID-19 Infection.

BACKGROUND: This study aims to determine if coagulation abnormalities at presentation are associated with clinical severity of pediatric COVID-19 infection. METHODS: We retrospectively reviewed admission coagulation studies (D-dimer, prothrombin time (PT), partial thromboplastin time with hepzyme, fibrinogen, and platelet count) with disease severity defined by need for ICU admission, ventilator support, and length of stay (LOS). RESULTS: There were 110 pediatric patients (0.5 months to 18 years) who had coagulation studies collected within 24 hours of admission. Patients who required ICU admission and ventilation support had significantly higher D-dimer and PT values at presentation compared to patients who required neither. In addition, D-dimer showed moderate correlation with LOS. CONCLUSIONS: Elevated D-dimer correlated significantly with severity of disease and LOS, while prolonged PT only correlated with disease severity. Our data suggest that D-dimer at presentation may predict a pediatric patient's need for ICU care or ventilator support.

Processing of artificial peptide-DNA-conjugates by the mitochondrial intermediate peptidase (MIP).

Import of DNA from the cytoplasm into the mitochondrial matrix is an obligatory step for an in organello site-directed mutagenesis or gene therapy approach on mitochondrial DNA diseases. In this context, we have developed an artificial DNA translocation vector that is composed of the mitochondrial signal peptide of the ornithine transcarbamylase (OTC) and a DNA moiety. While this vector is capable of directing attached passenger molecules to the mitochondrial matrix, the recognition of this artificial molecule by the endogenous mitochondrial signal peptide processing machinery as well as the cleavage of the peptide plays a pivotal role in the release of the attached DNA. To study the proteolytic processing of the artificial vector, various signal peptide-DNA-conjugates were treated with purified mitochondrial intermediate peptidase. When the leader peptide is directly linked to the DNA moiety without an intervening spacer, MIP processing is prevented. Cleavage of the peptide can be restored, however, when the first ten amino acid residues of the mature part of OTC are appended at the carboxy-terminal end of the signal peptide. Our results show that artificial peptide-DNA-conjugates are recognized by the mitochondrial proteolytic machinery, and therefore an interference of the peptide with the DNA function can be excluded.

Localization of the Ran-GTP binding protein RanBP2 at the cytoplasmic side of the nuclear pore complex.

A partial cDNA clone coding for the mouse homologue of the human Ran-GTP binding protein, RanBP2, has been isolated by screening of a murine expression library with antibodies to nup180, a previously identified nuclear pore complex protein (nucleoporin). Whether the antibodies cross-reacted with the polypeptide encoded by the cDNA clone or, alternatively, nup180 is proteolytically related to RanBP2, has not been determined. The 3795-bp open reading frame of the cDNA encodes a polypeptide consisting of 1265 amino acids with three Ran-GTP binding domains (RanBD) that are almost identical with published partial amino acid sequences of human RanBP2 as deduced from several partial cDNA clones of other authors. Sequence analysis further revealed that murine RanBP2 contains tandemly repeated zinc fingers of Cys2-Cys2 type and multiple copies of the FXFG nucleoporin "signature" motif clustered in regions preceding the RanBDs. Antibodies raised against a synthetic peptide of the derived amino acid sequence decorated the cytoplasmic rings of nuclear pore complexes (NPCs) as shown by immunogold electron microscopy. We suggest that the cytoplasmically disposed nucleoporin RanBP2 provides docking sites for import substrate-receptor complexes and, further, that the affinity of these sites to the transport substrate is modulated in a Ran-dependent fashion.

Nup180, a novel nuclear pore complex protein localizing to the cytoplasmic ring and associated fibrils.

Using an autoimmune serum from a patient with overlap connective tissue disease we have identified by biochemical and immunocytochemical approaches an evolutionarily conserved nuclear pore complex (NPC) protein with an estimated molecular mass of 180 kD and an isoelectric point of approximately 6.2 which we have designated as nup180. Extraction of isolated nuclear envelopes with 2 M urea and chromatography of the solubilized proteins on WGA-Sepharose demonstrated that nup180 is a peripheral membrane protein and does not react with WGA. Affinity-purified antibodies yielded a punctate immunofluorescent pattern of the nuclear surface of mammalian cells and stained brightly the nuclear envelope of cryosectioned Xenopus oocytes. Nuclei reconstituted in vitro in Xenopus egg extract were also stained in the characteristic punctate fashion. Immunogold EM localized nup180 exclusively to the cytoplasmic ring of NPCs and short fibers emanating therefrom into the cytoplasm. Antibodies to nup180 did not inhibit nuclear protein transport in vivo nor in vitro. Despite the apparent lack of involvement in NPC assembly or nucleocytoplasmic transport processes, the conservation of nup180 across species and its exclusive association with the NPC cytoplasmic ring suggests an important, though currently undefined function for this novel NPC protein.