Miastenia gravis de rápida instauración Santiago Cortés, Eva de; Cortés Durán, Petra María; Bedoya, María Jesús ...
Revista clínica de medicina de familia,
2021, Letnik:
14, Številka:
1
Journal Article
Recenzirano
Odprti dostop
RESUMEN La miastenia gravis es una enfermedad que se caracteriza por fatiga y debilidad muscular de predominio proximal, como son los músculos oculares, funciones bulbares, de las extremidades y de ...los músculos respiratorios. La evolución de la enfermedad suele ser fluctuante. Es la alteración más común dentro de las enfermedades que afectan a la transmisión neuromuscular. Los síntomas derivan de la agresión inmunológica contra la membrana postsináptica de la unión neuromuscular. Presentamos el caso de un hombre de 36 años que acude a consulta por parestesias al comer, que ceden espontáneamente a los pocos minutos. Dos semanas después es ingresado por diplopía y disfagia. Tras la sospecha de miastenia gravis, se realizan las pruebas complementarias pertinentes, concluyendo en el diagnóstico de miastenia gravis generalizada seronegativa asociada a timoma.
Separando y reciclando en el centro de salud Ruiz Chércoles, Esther; Encinas Rodríguez, Luz Divina; Escobar Gallegos, Mª del Mar ...
Pediatría Atención Primaria,
2020, Letnik:
22, Številka:
suppl 28
Journal Article
Upon activation, platelets secrete a 120-kDa protein that competes for the binding and internalization of acetyl low density lipoproteins (AcLDL) by macrophages. From the amino-terminal amino acid ...sequence, amino acid composition, and immunoblot analysis, we identified the active factor in platelet secretion products as sAPP, an alpha-secretase cleavage product of the beta-amyloid precursor protein (APP), that contains a Kunitz-type protease inhibitor (KPI) domain. We showed that both sAPP751 (also called Nexin II) and sAPP695, which does not contain a KPI domain, are ligands for the class A scavenger receptor (SR-A). Chinese hamster ovary cells stably transfected to express the SR-A bound and internalized 4-fold more human platelet-derived sAPP than control cells. The binding and internalization of sAPP were inhibited by the SR-A antagonist fucoidin. In addition, sAPP competed as effectively as fucoidin for SR-A-mediated cell association and degradation of (125)I-AcLDL. To determine if the KPI domain is required for the binding of sAPP to the SR-A, APP751 and APP695 were expressed in Chinese hamster ovary cells, and sAPP751 and sAPP695 purified from the medium were tested for their binding to the SR-A. sAPP751 and sAPP695 were equally effective in competing for the cell association of (125)I-AcLDL by SR-A-expressing cells, demonstrating that the KPI domain is not essential for binding. We also found that sAPP751 is present in extracts of atherosclerotic lesions and that sAPP competes for the SR-A-mediated cell association of oxidized low density lipoprotein. Deletion mutagenesis indicated that a negatively charged region of APP (residues 191-264) contributes to binding to the SR-A. These results suggest that the SR-A contributes to the clearance of sAPP and that sAPP competes for the cell association of other SR-A ligands.
A macromolecule in human platelet secretory products was demonstrated previously to inhibit the binding and uptake of acetoacetylated
(AcAc) low density lipoproteins (LDL) by scavenger receptors on ...mouse peritoneal macrophages. In the current study, this macromolecule
was purified to apparent homogeneity by DEAE-Sephacel chromatography, Sephacryl S-300 chromatography, and sucrose gradient
centrifugation. SDS-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of approximately
120 kDa. Chemical analysis indicated that the macromolecule (designated platelet-derived macrophage-binding proteoglycan (PDMBP))
was a chondroitin 4-sulfate proteoglycan with an approximately 32-kDa core protein. A polyclonal antibody produced against
this proteoglycan identified only PDMBP on Western blots of platelet secretory products and removed all ability of these products
to inhibit the binding of AcAc LDL to macrophages. Treatment of purified PDMBP with protease or chondroitinase AC or ABC abolished
the ability of the proteoglycan to inhibit the binding of AcAc LDL to macrophages. Binding studies using radiolabeled PDMBP
demonstrated that the proteoglycan bound directly to the macrophage cell surface and was competitively inhibited by AcAc LDL,
acetyl-LDL, fucoidin, and unlabeled PDMBP. PDMBP inhibited binding of 125I-labeled AcAc LDL to macrophages but had no effect
on binding to endothelial cells. The finding that PDMBP binds to the scavenger receptor on macrophages suggests a mechanism
for the inhibition of foam cell formation and suggests that the receptor could be involved in the plasma clearance of chondroitin
sulfate proteoglycans.
Upon activation, platelets secrete a 120-kDa protein that competes for the binding and internalization of acetyl low density
lipoproteins (AcLDL) by macrophages. From the amino-terminal amino acid ...sequence, amino acid composition, and immunoblot analysis,
we identified the active factor in platelet secretion products as sAPP, an α-secretase cleavage product of the β-amyloid precursor
protein (APP), that contains a Kunitz-type protease inhibitor (KPI) domain. We showed that both sAPP751 (also called Nexin
II) and sAPP695, which does not contain a KPI domain, are ligands for the class A scavenger receptor (SR-A). Chinese hamster
ovary cells stably transfected to express the SR-A bound and internalized 4-fold more human platelet-derived sAPP than control
cells. The binding and internalization of sAPP were inhibited by the SR-A antagonist fucoidin. In addition, sAPP competed
as effectively as fucoidin for SR-A-mediated cell association and degradation of 125 I-AcLDL. To determine if the KPI domain is required for the binding of sAPP to the SR-A, APP751 and APP695 were expressed
in Chinese hamster ovary cells, and sAPP751 and sAPP695 purified from the medium were tested for their binding to the SR-A.
sAPP751 and sAPP695 were equally effective in competing for the cell association of 125 I-AcLDL by SR-A-expressing cells, demonstrating that the KPI domain is not essential for binding. We also found that sAPP751
is present in extracts of atherosclerotic lesions and that sAPP competes for the SR-A-mediated cell association of oxidized
low density lipoprotein. Deletion mutagenesis indicated that a negatively charged region of APP (residues 191â264) contributes
to binding to the SR-A. These results suggest that the SR-A contributes to the clearance of sAPP and that sAPP competes for
the cell association of other SR-A ligands.
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