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1.
BMJ Mil Health ; 169(6): 510-516, 2023 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-34930818

RESUMEN

INTRODUCTION: This study aims to describe injury patterns, prehospital interventions and mortality rates of combat-related thoracic injuries during the past decade among Israel Defense Forces (IDF) soldiers before and after implementation of the 2012 IDF-Military Corps 'My Brother's Keeper' plan which included the publication of clinical practice guidelines (CPGs) for thoracic injuries, emphasis on adequate torso protection, introduction of modern life-saving procedures and encouragement of rapid evacuation. METHODS: The IDF prehospital trauma registry was reviewed to identify all patients who sustained thoracic injuries from January 2006 to December 2017. IDF soldiers who were injured, died of wounds or killed in action (KIA) were included. These were cross-referenced with the Israel National Trauma Registry. The periods before and after the plan were compared. RESULTS: 458 (12.3%) of 3733 IDF soldiers wounded on the battlefield sustained combat-related thoracic injuries. The overall mortality was 44.3% before the CPG and 17.3% after (p<0.001). Most were KIA: 97% (95 of 98) died by 30 June 2012, and 83% (20 of 24) after (p<0.001). Casualties treated with needle thoracostomy before and after CPG were 6.3% and 18.3%, respectively (p=0.002). More tube thoracostomies were performed after June 2012 (16.1% vs 5.4%, p=0.001). Evacuation was faster after June 2012 (119.4 min vs 560.8 min, p<0.001), but the rates of casualties evacuated within 60 min were similar (21.1% vs 25%, p=0.617). CONCLUSIONS: Among military casualties with thoracic injuries, the rate of life-saving interventions increased, evacuation time decreased and mortality dropped following the implementation of My Brother's Keeper plan.


Asunto(s)
Medicina Militar , Personal Militar , Traumatismos Torácicos , Humanos , Israel/epidemiología , Traumatismos Torácicos/terapia , Sistema de Registros , Medicina Militar/métodos
2.
J Cell Biol ; 112(3): 469-78, 1991 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-1846866

RESUMEN

The complementary DNAs for wildtype and tyrosine kinase-inactivated (K634A) forms of the PDGF beta-receptor were expressed in porcine aortic endothelial cells. We examined the internalization and degradation of ligands and receptors after exposure of receptor expressing cells to PDGF-BB, which binds to the beta-receptor with high affinity, and PDGF-AB, which binds with lower affinity. Cells expressing wildtype beta-receptors were able to internalize and degrade the receptor, as well as the ligand, after exposure to PDGF-BB or -AB. Cells expressing the kinase-inactivated mutant receptor also internalized and degraded both receptor and ligand, but with lower efficiency compared with the wildtype receptor cells. The degradation of either form of receptor was inhibited by treatment of the cells with the lysosomotropic drug chloroquine. Exposure of wildtype and K634A receptor expressing cells to PDGF-AB resulted in a twofold slower rate of internalization of this ligand as compared with PDGF-BB, whereas the relative rate of degradation was similar for the two ligands. Our data indicate that tyrosine kinase activity promotes, but is not a prerequisite for, ligand-induced internalization and degradation of the ligand-receptor complex.


Asunto(s)
Endocitosis , Factor de Crecimiento Derivado de Plaquetas/metabolismo , Proteínas Quinasas/metabolismo , Receptores de Superficie Celular/metabolismo , Animales , Línea Celular , Cloroquina/farmacología , Regulación hacia Abajo , Endotelio Vascular , Fibroblastos/metabolismo , Técnica del Anticuerpo Fluorescente , Humanos , Cinética , Proteínas Quinasas/genética , Receptores de Superficie Celular/efectos de los fármacos , Receptores de Superficie Celular/genética , Receptores del Factor de Crecimiento Derivado de Plaquetas , Piel , Porcinos , Transfección
3.
J Cell Biol ; 112(1): 55-63, 1991 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-1986007

RESUMEN

The intracellular sorting of EGF-receptor complexes (EGF-RC) has been studied in human epidermoid carcinoma A431 cells. Recycling of EGF was found to occur rapidly after internalization at 37 degrees C. The initial rate of EGF recycling was reduced at 18 degrees C. A significant pool of internalized EGF was incapable of recycling at 18 degrees C but began to recycle when cells were warmed to 37 degrees C. The relative rate of EGF outflow at 37 degrees C from cells exposed to an 18 degrees C temperature block was slower (t1/2 approximately 20 min) than the rate from cells not exposed to a temperature block (t1/2 approximately 5-7 min). These data suggest that there might be both short- and long-time cycles of EGF recycling in A431 cells. Examination of the intracellular EGF-RC dissociation and dynamics of short- and long-time recycling indicated that EGF recycled as EGF-RC. Moreover, EGF receptors that were covalently labeled with a photoactivatable derivative of 125I-EGF recycled via the long-time pathway at a rate similar to that of 125I-EGF. Since EGF-RC degradation was also blocked at 18 degrees C, we propose that sorting to the lysosomal and long-time recycling pathway may occur after a highly temperature-sensitive step, presumably in the late endosomes.


Asunto(s)
Factor de Crecimiento Epidérmico/metabolismo , Receptores ErbB/metabolismo , Células Tumorales Cultivadas/metabolismo , Carcinoma de Células Escamosas/metabolismo , Endocitosis/fisiología , Humanos , Radioisótopos de Yodo , Cinética , Temperatura
4.
Science ; 261(5121): 612-5, 1993 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-8342026

RESUMEN

The epidermal growth factor (EGF) receptor interacts with plasma membrane-associated adapter proteins during endocytosis through coated pits. Almost 50 percent of the total pool of alpha-adaptins was coimmunoprecipitated with the EGF receptor when A-431 cells were treated with EGF at 37 degrees C, but not at 4 degrees C. Partial proteolysis of alpha-adaptin suggested that the amino-terminal domain is the region that associates with the EGF receptor. The extent of receptor-adaptin association was increased in cells depleted of potassium to block endocytosis. These data suggest that receptor-adaptin association occurs in intact cells before coated pits are fully assembled.


Asunto(s)
Invaginaciones Cubiertas de la Membrana Celular/metabolismo , Endocitosis , Receptores ErbB/metabolismo , Proteínas/metabolismo , Subunidades alfa de Complejo de Proteína Adaptadora , Proteínas Adaptadoras del Transporte Vesicular , Factor de Crecimiento Epidérmico/metabolismo , Factor de Crecimiento Epidérmico/farmacología , Humanos , Fosforilación , Potasio/metabolismo , Temperatura , Células Tumorales Cultivadas , Tirosina/metabolismo
5.
Science ; 281(5381): 1357-60, 1998 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-9721102

RESUMEN

Eps15 homology (EH) domains are eukaryotic signaling modules that recognize proteins containing Asn-Pro-Phe (NPF) sequences. The structure of the central EH domain of Eps15 has been solved by heteronuclear magnetic resonance spectroscopy. The fold consists of a pair of EF hand motifs, the second of which binds tightly to calcium. The NPF peptide is bound in a hydrophobic pocket between two alpha helices, and binding is mediated by a critical aromatic interaction as revealed by structure-based mutagenesis. The fold is predicted to be highly conserved among 30 identified EH domains and provides a structural basis for defining EH-mediated events in protein trafficking and growth factor signaling.


Asunto(s)
Proteínas de Unión al Calcio/química , Oligopéptidos/metabolismo , Fosfoproteínas/química , Conformación Proteica , Secuencia de Aminoácidos , Sitios de Unión , Calcio/metabolismo , Proteínas de Unión al Calcio/metabolismo , Secuencias Hélice-Asa-Hélice , Ligandos , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Resonancia Magnética Nuclear Biomolecular , Oligopéptidos/química , Fosfoproteínas/metabolismo , Unión Proteica , Pliegue de Proteína , Estructura Secundaria de Proteína , Transducción de Señal
6.
Artículo en Inglés | MEDLINE | ID: mdl-32051781

RESUMEN

Intramedullary nailing is used to stabilize distal femoral, proximal tibial, and distal tibial periarticular fractures with short proximal or distal segments, as well as some intra-articular fractures in which a stable articular block can be created. Intramedullary nailing may be beneficial in complex fracture patterns with diaphyseal extension, segmental injuries, or patients who might benefit from a decreased incision burden. Step 1: Preoperative planning. Review imaging and make sure there is a nail with adequate interlocks. Consider the use of adjunctive techniques to obtain and maintain alignment, and how intra-articular fracture lines will be stabilized. Step 2: Position and prepare the patient. Step 3: Exposure for nailing via suprapatellar, infrapatellar, or knee arthrotomy approaches. Limited exposure of fracture planes may also be necessary for adjunctive techniques. Step 4: Convert an OTA/AO C-type fracture to an A-type fracture if needed. Step 5: Obtain appropriate starting point and trajectory with the nail starting wire and use the opening reamer. Step 6: Obtain reduction, if not yet done, and pass the ball-tipped reaming wire across the fracture. Step 7: Ream while holding reduction. Step 8: Pass nail. Step 9: Verify reduction is maintained and correct if needed. Step 10: Place interlocks, preferably multiplanar, in the short segment. Create a fixed angle construct if desired and convert adjunctive techniques/provisional fixation to definitive fixation as needed. Step 11: Perform final checks. Step 12: Closure. Step 13: Postoperative plan. For extra-articular fractures, one may expect healing with maintained alignment from what was present at the case end intraoperatively in the vast majority of cases. For intra-articular fractures, development of posttraumatic arthritis is an additional concern.

7.
Curr Biol ; 11(3): 185-90, 2001 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-11231154

RESUMEN

Adenylyl cyclases possess complex structures like those of the ATP binding cassette (ABC) transporter family, which includes the cystic fibrosis transmembrane regulator, the P-glycoprotein, and ATP-sensitive K(+) channels [1-4]. These structures comprise a cytosolic N terminus followed by two tandem six-transmembrane cassettes, each associated with a highly homologous (ATP binding) cytosolic loop [5-8]. The catalytic domains, which are located in the two large cytoplasmic loops, are highly conserved and well studied. The crystal structure of these domains has even been described recently [9, 10]. However, nothing is known of the function or organization of the 12 transmembrane segments. In the present study we adopted a range of strategies including live-cell fluorescence resonance energy transfer (FRET) microscopy, coimmunoprecipitation, and functional assays of various truncated and substituted, fluorescently-tagged molecules to analyze the trafficking and activity of this molecule. When expressed as individual peptides, the two transmembrane domains - largely independently of any cytosolic region - formed a tight complex that was delivered to the plasma membrane. This cooperation between the two intact transmembrane domains was essential and sufficient to target the enzyme to the plasma membrane of the cell. The extracellular loop between the ninth and tenth transmembrane segments, which contains an N-glycosylation site, was also necessary. Furthermore, the interaction between the two transmembrane clusters played a critical role in bringing together the cytosolic catalytic domains to express functional adenylyl cyclase activity in the intact cell.


Asunto(s)
Adenilil Ciclasas/metabolismo , Membrana Celular/metabolismo , Transferencia de Energía , Fluorescencia , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/metabolismo
8.
Curr Biol ; 10(21): 1395-8, 2000 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-11084343

RESUMEN

The interaction of activated epidermal growth factor receptor (EGFR) with the Src homology 2 (SH2) domain of the growth-factor-receptor binding protein Grb2 initiates signaling through Ras and mitogen-activated protein kinase (MAP kinase) [1,2]. Activation of EGFRs by ligand also triggers rapid endocytosis of EGF-receptor complexes. To analyze the spatiotemporal regulation of EGFR-Grb2 interactions in living cells, we have combined imaging microscopy with a modified method of measuring fluorescence resonance energy transfer (FRET) on a pixel-by-pixel basis using EGFR fused to cyan fluorescent protein (CFP) and Grb2 fused to yellow fluorescent protein (YFP). Efficient energy transfer between CFP and YFP should only occur if CFP and YFP are less than 50A apart, which requires direct interaction of the EGFR and Grb2 fused to these fluorescent moieties [3]. Stimulation by EGF resulted in the recruitment of Grb2-YFP to cellular compartments that contained EGFR-CFP and a large increase in FRET signal amplitude. In particular, FRET measurements indicated that activated EGFR-CFP interacted with Grb2-YFP in membrane ruffles and endosomes. These results demonstrate that signaling via EGFRs can occur in the endosomal compartment. The work also highlights the potential of FRET microscopy in the study of subcellular compartmentalization of protein-protein interactions in living cells.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Receptores ErbB/metabolismo , Microscopía Fluorescente/métodos , Proteínas/metabolismo , Animales , Aorta/citología , Extensiones de la Superficie Celular/metabolismo , Células Cultivadas , Endosomas/metabolismo , Endotelio , Colorantes Fluorescentes/metabolismo , Proteína Adaptadora GRB2 , Sistema de Señalización de MAP Quinasas , Modelos Biológicos , Unión Proteica , Transporte de Proteínas , Proteínas Recombinantes de Fusión/metabolismo , Espectrometría de Fluorescencia
9.
Mol Biol Cell ; 10(8): 2687-702, 1999 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10436022

RESUMEN

The clathrin assembly lymphoid myeloid leukemia (CALM) gene encodes a putative homologue of the clathrin assembly synaptic protein AP180. Hence the biochemical properties, the subcellular localization, and the role in endocytosis of a CALM protein were studied. In vitro binding and coimmunoprecipitation demonstrated that the clathrin heavy chain is the major binding partner of CALM. The bulk of cellular CALM was associated with the membrane fractions of the cell and localized to clathrin-coated areas of the plasma membrane. In the membrane fraction, CALM was present at near stoichiometric amounts relative to clathrin. To perform structure-function analysis of CALM, we engineered chimeric fusion proteins of CALM and its fragments with the green fluorescent protein (GFP). GFP-CALM was targeted to the plasma membrane-coated pits and also found colocalized with clathrin in the Golgi area. High levels of expression of GFP-CALM or its fragments with clathrin-binding activity inhibited the endocytosis of transferrin and epidermal growth factor receptors and altered the steady-state distribution of the mannose-6-phosphate receptor in the cell. In addition, GFP-CALM overexpression caused the loss of clathrin accumulation in the trans-Golgi network area, whereas the localization of the clathrin adaptor protein complex 1 in the trans-Golgi network remained unaffected. The ability of the GFP-tagged fragments of CALM to affect clathrin-mediated processes correlated with the targeting of the fragments to clathrin-coated areas and their clathrin-binding capacities. Clathrin-CALM interaction seems to be regulated by multiple contact interfaces. The C-terminal part of CALM binds clathrin heavy chain, although the full-length protein exhibited maximal ability for interaction. Altogether, the data suggest that CALM is an important component of coated pit internalization machinery, possibly involved in the regulation of clathrin recruitment to the membrane and/or the formation of the coated pit.


Asunto(s)
Clatrina/metabolismo , Endocitosis/fisiología , Proteínas de Ensamble de Clatrina Monoméricas , Proteínas del Tejido Nervioso/metabolismo , Fosfoproteínas/metabolismo , Proteínas Adaptadoras del Transporte Vesicular , Animales , Transporte Biológico , Células COS/metabolismo , Clatrina/genética , Invaginaciones Cubiertas de la Membrana Celular/metabolismo , Endosomas/metabolismo , Receptores ErbB/metabolismo , Aparato de Golgi/metabolismo , Proteínas Fluorescentes Verdes , Humanos , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Proteínas del Tejido Nervioso/genética , Fosfoproteínas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
10.
Oncogene ; 8(11): 3021-8, 1993 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8105439

RESUMEN

The endocytosis of gp185erbB-2 was studied using chimeric receptors in which the intracellular domain of erbB-2, or subdomins thereof, was substituted for the corresponding regions of the epidermal growth factor (EGF) receptor. Chimeric and wild-type EGF or erbB-2 receptors were expressed in mouse NIH3T3 or NR6 fibroblasts and in a human mammary adenocarcinoma cell line, MDAMB-134. The rate of EGF-induced internalization for the chimera consisting of the extracellular EGF receptor domain and intracellular erbB-2 domain was reduced three- to fourfold compared with the wild-type EGF receptor. The low rate of internalization of the chimeric receptor resulted in impaired down-regulation and degradation of the receptor. Substitution of the carboxyl terminus of erbB-2 for the corresponding region of the EGF receptor caused a similar decrease of receptor endocytosis, whereas substitution of the erbB-2 tyrosine kinase domain did not affect internalization and down-regulation. Since the tyrosine kinase of the internalization-defective chimeric receptors could be activated by EGF, kinase activity and autophosphorylation of erbB-2 do not appear to be sufficient for a maximum rapid internalization of the chimeric receptors. These results suggest that the carboxyl terminus of erbB-2 either does not possess all the signals required for the rapid internalization or contains an inhibitory signal for rapid internalization.


Asunto(s)
Receptores ErbB/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Secuencia de Aminoácidos , Animales , Línea Celular , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo , Factor de Crecimiento Epidérmico/metabolismo , Factor de Crecimiento Epidérmico/farmacología , Receptores ErbB/análisis , Receptores ErbB/química , Humanos , Ratones , Datos de Secuencia Molecular , Proteínas Proto-Oncogénicas/análisis , Proteínas Proto-Oncogénicas/química , Receptor ErbB-2
11.
Biochim Biophys Acta ; 1011(1): 88-96, 1989 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-2784329

RESUMEN

The fate of epidermal growth factor (EGF) after internalization by human carcinoma A431 cells has been studied. Cells were allowed to internalize 125I-EGF for 10 min at 37 degrees C and treated with acid/salt solution to remove non-internalized ligand. Further incubation of these '125I-EGF-loaded' cells at 37 degrees C results in rapid recycling of internalized 125I-EGF-receptor complexes back to the cell surface. Recycling was assessed by measuring the increase in plasma membrane pool of 125I-EGF-receptor complexes as they became sensitive to acid/salt treatment, cross-linking with the membrane impermeant reagent bis(sulfosuccinimidyl)suberate and competitive substitution by unlabeled EGF. Moreover, redistribution of 125I-EGF-receptor complexes from endosomes to the plasma membrane was demonstrated using a subcellular fractionation technique. More than 50% of the total internalized EGF was found to be capable of recycling. The rate of recycling was significantly higher than that of EGF degradation in lysosomes. It was shown that EGF/receptor recycling is an energy-requiring and temperature-dependent process. Fluorescence microscopy studies demonstrate that endosomes located in a region adjacent to the Golgi complex are involved in the the recycling of EGF-receptor complexes in A431 cells. The data obtained suggest that dissociation of EGF from internalized receptor is not necessary for EGF receptor recycling.


Asunto(s)
Factor de Crecimiento Epidérmico/metabolismo , Receptores ErbB/metabolismo , Animales , Unión Competitiva , Fraccionamiento Celular , Membrana Celular/metabolismo , Reactivos de Enlaces Cruzados , Metabolismo Energético , Colorantes Fluorescentes , Aparato de Golgi/metabolismo , Humanos , Cinética , Ratones , Microscopía Fluorescente , Succinimidas , Temperatura , Células Tumorales Cultivadas
12.
Am J Psychiatry ; 138(3): 334-9, 1981 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-7468829

RESUMEN

The Lanterman-Petris-Short Act in California has been acclaimed for protecting the civil rights of the mentally ill and curbing unnecessary involuntary psychiatric hospitalization. Its passage, however, has not prevented an increase in the rate of involuntary admissions to state hospitals and a marked decrease in the rate of voluntary admissions. This has greatly changed the functions and problems of state hospitals. In local as well as state hospitals large numbers of people continue to become involuntary psychiatric patients. In many cases this results from gaps between the law and its implementation. It appears that professionals, the courts, families, and society generally feel a continuing need for social control of the mentally ill.


Asunto(s)
Internamiento Obligatorio del Enfermo Mental/legislación & jurisprudencia , Psiquiatría Forense/legislación & jurisprudencia , Enfermos Mentales , California , Derechos Civiles/legislación & jurisprudencia , Servicios Comunitarios de Salud Mental/estadística & datos numéricos , Hospitales Psiquiátricos/estadística & datos numéricos , Hospitales Provinciales/estadística & datos numéricos , Humanos , Trastornos Mentales/terapia , Defensa del Paciente
13.
FEBS Lett ; 221(1): 105-9, 1987 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-3497821

RESUMEN

The fate of epidermal growth factor (EGF) after internalization by A431 cells was studied. First, cells containing 125I-EGF-receptor complexes in endosomes were obtained. Subsequent incubation of the cells at 37 degrees C resulted in the recycling of 125I-EGF from endosomes to the cell surface in the receptor-bound state and the gradual release of recycled ligand into the medium. The excess of unlabeled EGF blocked both rebinding and re-internalization of recycled 125I-EGF to produce enhanced accumulation of ligand in the medium. The rate of recycling was shown to be much higher than that of EGF degradation.


Asunto(s)
Carcinoma de Células Escamosas/metabolismo , Factor de Crecimiento Epidérmico/metabolismo , Animales , Fraccionamiento Celular , Línea Celular , Membrana Celular/metabolismo , Centrifugación por Gradiente de Densidad , Citoplasma/metabolismo , Endocitosis , Receptores ErbB/metabolismo , Humanos , Cinética , Ratones
14.
Soc Sci Med ; 22(3): 345-9, 1986.
Artículo en Inglés | MEDLINE | ID: mdl-3961549

RESUMEN

The paper briefly discusses the importance of macro-economic policy in health sector financing. The ways in which monetary and fiscal policy (macro-economic policy) affect interest rates, price levels and aggregate output are presented. The main portion of the paper considers a variety of methods for public financing of health and development projects. These approaches are analyzed in light of distributional and efficiency considerations. One way of increasing health sector resources is through reallocation from other sectors of the economy. The potential for redistribution from the defense to the health service industry is briefly considered.


Asunto(s)
Recursos en Salud/economía , Países en Desarrollo , Honorarios Médicos , Financiación Gubernamental , Organización de la Financiación , Servicios de Salud/economía , Servicios de Salud/estadística & datos numéricos , Humanos
15.
J Orthop Trauma ; 16(6): 425-30, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12142833

RESUMEN

Many different techniques have been reported for the treatment of clavicular nonunions. Those techniques involving screws and plate generally position the plate on the superior (subcutaneous) surface of the clavicle. To decrease the risk of screw pull-out and prominence of the instrumentation, we currently perform anteroinferior plating using a 3.5-millimeter pelvic reconstruction plate with a lag screw and bone graft. A consecutive group of twelve patients with midshaft clavicular nonunions was treated with this technique. All nonunions united after an average of 3.6 months (range 2 to 8 months). All patients regained full function and mobility of the shoulder. The technique as described in this article illustrates a successful modification of the traditional plating technique of midshaft clavicular nonunions. We conclude that anteroinferior plating is a reliable and safe technique that leads to high rates of bony union in midshaft clavicular nonunions.


Asunto(s)
Placas Óseas , Clavícula/lesiones , Fracturas no Consolidadas/cirugía , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Procedimientos Ortopédicos/métodos , Estudios Retrospectivos
16.
Tsitologiia ; 25(7): 784-92, 1983 Jul.
Artículo en Ruso | MEDLINE | ID: mdl-6623636

RESUMEN

A mathematical model has been analysed describing uridine uptake in mammalian cells as a tandem process that involves membrane transport and uridine phosphorylation within the cell. The measurement of kinetic parametres of uridine uptake in 3T6 cells showed that the transport system possesses a low affinity to uridine (Kt = 145 microM) and a high velocity (Vt = 10 microM/sec), whereas the phosphorylation system possesses a high affinity for uridine (Ke = 10 microM) and a low velocity (Ve = 0.17 microM/sec). A method of construction of "ideal" curves was proposed, describing the time dependence of uridine uptake which helps to verify values of kinetic parameters obtained. On the basis of the theoretical analysis and generalization of experimental data it was concluded that the optimum conditions of uridine transport parameters measuring at 25 degrees C involve the uridine concentration in the medium equal to 20-200 microM, and the time of cell incubation, 2-20 sec, while the optimum conditions of uridine phosphorilation parameters measuring being its concentration in the medium 5-20 microM and the cell incubation longer than 1 minute.


Asunto(s)
Fibroblastos/metabolismo , Modelos Biológicos , Uridina/metabolismo , Animales , Transporte Biológico , Línea Celular , Células Cultivadas , Cinética , Matemática , Métodos , Ratones , Fosforilación
17.
Tsitologiia ; 26(6): 699-705, 1984 Jun.
Artículo en Ruso | MEDLINE | ID: mdl-6528367

RESUMEN

A comparison was made among rates of uptake of 3H-uridine, 3H-glycerol and 3H-D-xylose into mouse fibroblasts of line L sensitive to ethidium bromide (EB), and into EB-resistant cells obtained from this line by selection. Constants of uridine transport and phosphorylation were determined. For EB sensitive L cells Kt was 162 +/- 27 microM, Vt was 7.5 +/- 0.7 microM/sec. For EB resistant cells Kt was 178 +/- 27 microM, and Vt was 4.6 +/- 0.2 microM/sec. Thus, the transport rate of uridine in resistant cells was twice lower than in EB sensitive cells. The rate of uridine phosphorilation in EB resistant cells was by three times lower than in EB sensitive ones. The uptake of glycerol into resistant cells was also lowered. There was no difference in transport of 3H-D-xylose between sensitive and resistant cells. The data obtained may suggest some changes in plasma membrane in the EB resistant cells.


Asunto(s)
Etidio/farmacología , Glicerol/metabolismo , Células L/metabolismo , Uridina/metabolismo , Animales , Transporte Biológico/efectos de los fármacos , Células Clonales/efectos de los fármacos , Células Clonales/metabolismo , Resistencia a Medicamentos , Células L/efectos de los fármacos , Ratones , Fosforilación , Factores de Tiempo , Xilosa/metabolismo
18.
Tsitologiia ; 34(8): 74-81, 1992.
Artículo en Ruso | MEDLINE | ID: mdl-1293877

RESUMEN

The platelet-derived growth factor (PDGF) is a major mitogen in serum for connective tissue derived cells in culture. The influence of receptor structure on the ability of PDGF receptor to be internalized was studied using cell lines transfected with different PDGF-receptor constructions. CHO cell lines expressing either normal PDGF receptor (CHO wt cells) or truncated PDGF receptor, lacking all but 19 amino acids of the intracellular domain (CHO-ECTM cells) were stained according to the method of indirect immunofluorescence with monoclonal antibody B2 to PDGF receptor. It has been found that after a 30-min incubation of the CHO wt cells at 37 degrees C in the presence of PDGF-BB a typical process of endocytosis is observed, while after a 2 h incubation in the same conditions the staining of the cells is absent which suggested the existence of the down-regulation and the process of degradation of PDGF receptor in CHO wt cells. In contrast, in the case of CHO-ECTM cells after both 30-min and 2-h incubation of cells in the presence of PDGF-BB a bright staining of margins and a low staining of the cytoplasm are observed. When the cells where incubated in the presence of lysosomotropic drug chloroquine (0.1 mM), that inhibits degradation of the receptor, the immunostaining of CHO wt cells is changed, with bright compact spots appearing. But in CHO-ECTM cells the fluorescence pattern is not changed. To examine the rate of endocytosis of PDGF-BB, both the types of cells were incubated in the presence of 2 ng/ml of 125I-PDGF-BB.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Endocitosis/fisiología , Mutación/fisiología , Receptores del Factor de Crecimiento Derivado de Plaquetas/metabolismo , Animales , Línea Celular , Células Cultivadas/metabolismo , Cloroquina , Cricetinae , Cricetulus , Femenino , Técnica del Anticuerpo Fluorescente , Radioisótopos de Yodo , Ligandos , Ovario , Factor de Crecimiento Derivado de Plaquetas/metabolismo , Proteínas Recombinantes/metabolismo , Factores de Tiempo
19.
Tsitologiia ; 23(4): 419-26, 1981 Apr.
Artículo en Ruso | MEDLINE | ID: mdl-6167038

RESUMEN

Uridine transport and phosphorylation were studied in cultured Swiss 3T3 CHO-K1 cells, differing in their growth characteristics. Uridine was shown to be transported to the cell with a high rate. With the 2 micronM uridine concentration in the medium, the stationary level of free uridine in cells is reached 10 seconds following incubation at 25 degrees, and the further uridine uptake is limited by phosphorylation.. The uridine transport to the cell does not depend on the DNA synthesis level and the growth phase of 3T3 and CHO-K1 cells. With the increase in culture density, the rate of uridine phosphorylation decreases in 3T3 cells being actually unchanged in CHO-K1 cells. With the equal cell density in both the cases, the phosphorylation rate in CHO-K1 cells is by several times higher than that in 3T3 cells. A positive correlation between uridine phosphorylation rate and DNA synthesis has been observed under various cultivation condition of CHO-K1 cells.


Asunto(s)
Células Cultivadas/metabolismo , Fosforilación Oxidativa , Uridina/metabolismo , Animales , Transporte Biológico , Línea Celular , Cricetinae , Cricetulus , ADN/biosíntesis , Ratones , Ratones Endogámicos , ARN/metabolismo
20.
Tsitologiia ; 23(5): 523-30, 1981 May.
Artículo en Ruso | MEDLINE | ID: mdl-6167039

RESUMEN

In the serum-deficient medium, the cultured Swiss 3T3 and CHO-K1 cells transit to the resting state. The rates of uridine phosphorylation and RNA synthesis in these cells are lowered. After the addition of fresh medium containing 10% serum, cell proliferation is induced. At the early stage of cell entrance into the cell cycle uridine transport through the cell plasma membrane remains unchanged in both cultures. During the 1st hour after serum addition the rate of uridine phosphorylation increases in 3T3 cells to remain practically unchanged in CHO-K1 cells. At this time, RNA synthesis in cells increases almost twofold in both cultures. A correlation has been revealed between the initial level of uridine phosphorylation in 3T3 cells and the percentage of its maximal elevation after serum addition. No such a correlation was observed for CHO-K1 cells. The rate of uridine phosphorylation in arrested CHO-K1 cells is higher than that in 3T3 cells. It has been included that the initial increase of uridine phosphorylation during serum stimulation may be not obligatory for all cell types, but depends on the level of uridine kinase activity before serum addition to the cells.


Asunto(s)
Células Cultivadas/metabolismo , Uridina/metabolismo , Animales , Transporte Biológico/efectos de los fármacos , División Celular/efectos de los fármacos , Cricetinae , Medios de Cultivo , ADN/biosíntesis , Sueros Inmunes/farmacología , Ratones , Fosforilación Oxidativa/efectos de los fármacos , ARN/biosíntesis
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