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1.
BMJ Mil Health ; 169(6): 510-516, 2023 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-34930818

RESUMO

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.


Assuntos
Medicina Militar , Militares , Traumatismos Torácicos , Humanos , Israel/epidemiologia , Traumatismos Torácicos/terapia , Sistema de Registros , Medicina Militar/métodos
2.
J Cell Biol ; 112(3): 469-78, 1991 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-1846866

RESUMO

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.


Assuntos
Endocitose , Fator de Crescimento Derivado de Plaquetas/metabolismo , Proteínas Quinases/metabolismo , Receptores de Superfície Celular/metabolismo , Animais , Linhagem Celular , Cloroquina/farmacologia , Regulação para Baixo , Endotélio Vascular , Fibroblastos/metabolismo , Imunofluorescência , Humanos , Cinética , Proteínas Quinases/genética , Receptores de Superfície Celular/efeitos dos fármacos , Receptores de Superfície Celular/genética , Receptores do Fator de Crescimento Derivado de Plaquetas , Pele , Suínos , Transfecção
3.
J Cell Biol ; 112(1): 55-63, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1986007

RESUMO

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.


Assuntos
Fator de Crescimento Epidérmico/metabolismo , Receptores ErbB/metabolismo , Células Tumorais Cultivadas/metabolismo , Carcinoma de Células Escamosas/metabolismo , Endocitose/fisiologia , Humanos , Radioisótopos do Iodo , Cinética , Temperatura
4.
Science ; 261(5121): 612-5, 1993 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-8342026

RESUMO

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.


Assuntos
Invaginações Revestidas da Membrana Celular/metabolismo , Endocitose , Receptores ErbB/metabolismo , Proteínas/metabolismo , Subunidades alfa do Complexo de Proteínas Adaptadoras , Proteínas Adaptadoras de Transporte Vesicular , Fator de Crescimento Epidérmico/metabolismo , Fator de Crescimento Epidérmico/farmacologia , Humanos , Fosforilação , Potássio/metabolismo , Temperatura , Células Tumorais Cultivadas , Tirosina/metabolismo
5.
Science ; 281(5381): 1357-60, 1998 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-9721102

RESUMO

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.


Assuntos
Proteínas de Ligação ao Cálcio/química , Oligopeptídeos/metabolismo , Fosfoproteínas/química , Conformação Proteica , Sequência de Aminoácidos , Sítios de Ligação , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Sequências Hélice-Alça-Hélice , Ligantes , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Ressonância Magnética Nuclear Biomolecular , Oligopeptídeos/química , Fosfoproteínas/metabolismo , Ligação Proteica , Dobramento de Proteína , Estrutura Secundária de Proteína , Transdução de Sinais
6.
Artigo em Inglês | MEDLINE | ID: mdl-32051781

RESUMO

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.
Artigo em Inglês | MEDLINE | ID: mdl-11231154

RESUMO

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.


Assuntos
Adenilil Ciclases/metabolismo , Membrana Celular/metabolismo , Transferência de Energia , Fluorescência , Proteínas de Fluorescência Verde , Proteínas Luminescentes/metabolismo
8.
Curr Biol ; 10(21): 1395-8, 2000 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-11084343

RESUMO

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.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Receptores ErbB/metabolismo , Microscopia de Fluorescência/métodos , Proteínas/metabolismo , Animais , Aorta/citologia , Extensões da Superfície Celular/metabolismo , Células Cultivadas , Endossomos/metabolismo , Endotélio , Corantes Fluorescentes/metabolismo , Proteína Adaptadora GRB2 , Sistema de Sinalização das MAP Quinases , Modelos Biológicos , Ligação Proteica , Transporte Proteico , Proteínas Recombinantes de Fusão/metabolismo , Espectrometria de Fluorescência
9.
Mol Biol Cell ; 10(8): 2687-702, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10436022

RESUMO

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.


Assuntos
Clatrina/metabolismo , Endocitose/fisiologia , Proteínas Monoméricas de Montagem de Clatrina , Proteínas do Tecido Nervoso/metabolismo , Fosfoproteínas/metabolismo , Proteínas Adaptadoras de Transporte Vesicular , Animais , Transporte Biológico , Células COS/metabolismo , Clatrina/genética , Invaginações Revestidas da Membrana Celular/metabolismo , Endossomos/metabolismo , Receptores ErbB/metabolismo , Complexo de Golgi/metabolismo , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Proteínas do Tecido Nervoso/genética , Fosfoproteínas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
10.
Oncogene ; 8(11): 3021-8, 1993 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8105439

RESUMO

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.


Assuntos
Receptores ErbB/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular , Relação Dose-Resposta a Droga , Regulação para Baixo , Fator de Crescimento Epidérmico/metabolismo , Fator de Crescimento Epidérmico/farmacologia , Receptores ErbB/análise , Receptores ErbB/química , Humanos , Camundongos , Dados de Sequência Molecular , Proteínas Proto-Oncogênicas/análise , Proteínas Proto-Oncogênicas/química , Receptor ErbB-2
11.
Biochim Biophys Acta ; 1011(1): 88-96, 1989 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-2784329

RESUMO

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.


Assuntos
Fator de Crescimento Epidérmico/metabolismo , Receptores ErbB/metabolismo , Animais , Ligação Competitiva , Fracionamento Celular , Membrana Celular/metabolismo , Reagentes de Ligações Cruzadas , Metabolismo Energético , Corantes Fluorescentes , Complexo de Golgi/metabolismo , Humanos , Cinética , Camundongos , Microscopia de Fluorescência , Succinimidas , Temperatura , Células Tumorais Cultivadas
12.
Am J Psychiatry ; 138(3): 334-9, 1981 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7468829

RESUMO

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.


Assuntos
Internação Compulsória de Doente Mental/legislação & jurisprudência , Psiquiatria Legal/legislação & jurisprudência , Pessoas Mentalmente Doentes , California , Direitos Civis/legislação & jurisprudência , Serviços Comunitários de Saúde Mental/estatística & dados numéricos , Hospitais Psiquiátricos/estatística & dados numéricos , Hospitais Estaduais/estatística & dados numéricos , Humanos , Transtornos Mentais/terapia , Defesa do Paciente
13.
FEBS Lett ; 221(1): 105-9, 1987 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-3497821

RESUMO

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.


Assuntos
Carcinoma de Células Escamosas/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Animais , Fracionamento Celular , Linhagem Celular , Membrana Celular/metabolismo , Centrifugação com Gradiente de Concentração , Citoplasma/metabolismo , Endocitose , Receptores ErbB/metabolismo , Humanos , Cinética , Camundongos
14.
Soc Sci Med ; 22(3): 345-9, 1986.
Artigo em Inglês | MEDLINE | ID: mdl-3961549

RESUMO

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.


Assuntos
Recursos em Saúde/economia , Países em Desenvolvimento , Honorários Médicos , Financiamento Governamental , Organização do Financiamento , Serviços de Saúde/economia , Serviços de Saúde/estatística & dados numéricos , Humanos
15.
J Orthop Trauma ; 16(6): 425-30, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12142833

RESUMO

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.


Assuntos
Placas Ósseas , Clavícula/lesões , Fraturas não Consolidadas/cirurgia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Ortopédicos/métodos , Estudos Retrospectivos
16.
Tsitologiia ; 25(7): 784-92, 1983 Jul.
Artigo em Russo | MEDLINE | ID: mdl-6623636

RESUMO

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.


Assuntos
Fibroblastos/metabolismo , Modelos Biológicos , Uridina/metabolismo , Animais , Transporte Biológico , Linhagem Celular , Células Cultivadas , Cinética , Matemática , Métodos , Camundongos , Fosforilação
17.
Tsitologiia ; 26(6): 699-705, 1984 Jun.
Artigo em Russo | MEDLINE | ID: mdl-6528367

RESUMO

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.


Assuntos
Etídio/farmacologia , Glicerol/metabolismo , Células L/metabolismo , Uridina/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Células Clonais/efeitos dos fármacos , Células Clonais/metabolismo , Resistência a Medicamentos , Células L/efeitos dos fármacos , Camundongos , Fosforilação , Fatores de Tempo , Xilose/metabolismo
18.
Tsitologiia ; 30(11): 1311-7, 1988 Nov.
Artigo em Russo | MEDLINE | ID: mdl-3266692

RESUMO

Endocytosis of the epidermal growth factor (EGF) was investigated in three cell lines--A431, 3T6 and Swiss 3T3--after their incubation with cytochalasin B (CB). CB was introduced into culture medium (10 mkg/ml) 1.5-2 hours before addition of 125I-EGF (20-40 ng/ml). The label uptake rate was measured after a 35-40 minutes incubation of cells with 125I-EGF. It appeared that disorganization of microfilamentous network caused by CB exerted no influence on the binding of EGF to the surface membrane receptors and its internalization. Nevertheless, the experiments performed on A431 cells using a fluorescent label--rhodamine--bound to EGF (EGF-R) indicate that CB, though not influencing the initial steps of endocytosis, inhibits the next step--the intracellular transport of EGF-receptor complexes from the trans-Golgi region to lysosomes. As was shown elsewhere (Barkan, Nikol'sky, 1986), CB inhibits the mitogenic effect of EGF on resting Swiss 3T3 cells. So, the process of EGF-receptor uptake and delivery to the trans-Golgi region is evidently not enough to stimulate the cell proliferation; next steps of transport and degradation of ligand-receptor complexes are presumably needed.


Assuntos
Actinas , Citocalasina B/farmacologia , Citoesqueleto/efeitos dos fármacos , Endocitose/efeitos dos fármacos , Fator de Crescimento Epidérmico/metabolismo , Animais , Receptores ErbB/efeitos dos fármacos , Humanos , Camundongos , Células Tumorais Cultivadas/efeitos dos fármacos
19.
Tsitologiia ; 29(8): 904-10, 1987 Aug.
Artigo em Russo | MEDLINE | ID: mdl-3318045

RESUMO

Dynamics of compartmentalization of epidermal growth factor (EGF) in human carcinoma A431 cells during the first hour after initiation of endocytosis was examined by methods of the organelle fractionation on a 20% Percoll gradient and of the microfluorimetric visualization of endocytosis of rhodamine-labeled EGF (EGF-R). EGF was revealed in small vesicles localized in the peripheral region of cytoplasm in a few minutes after endocytosis initiation. During centrifugation in Percoll these vesicles (endosomes), with an average density of 1.038 g/ml, were seen co-sedimented with Golgi membranes. By one hour after initiation of endocytosis, EGF-R was accumulated in perinuclear zone, in a trans-Golgi region, as numerous big luminous centres that were apparently MB-endosomes and had the same density in Percoll as did small peripheral endosomes. Such centres appeared in several cells already within 5-10 minutes. In A431 cells EGF did not reach lysosomes within 60 minutes, because no accumulation of 125I-EGF was shown in lysosome corresponding regions of Percoll gradient (average density 1.070 g/ml).


Assuntos
Carcinoma de Células Escamosas/metabolismo , Compartimento Celular , Fator de Crescimento Epidérmico/metabolismo , Animais , Carcinoma de Células Escamosas/ultraestrutura , Linhagem Celular , Técnicas Citológicas , Endocitose , Humanos , Camundongos , Microscopia de Fluorescência , Organoides/metabolismo , Organoides/ultraestrutura , Fatores de Tempo , Células Tumorais Cultivadas
20.
Tsitologiia ; 34(8): 74-81, 1992.
Artigo em Russo | MEDLINE | ID: mdl-1293877

RESUMO

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)


Assuntos
Endocitose/fisiologia , Mutação/fisiologia , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismo , Animais , Linhagem Celular , Células Cultivadas/metabolismo , Cloroquina , Cricetinae , Cricetulus , Feminino , Imunofluorescência , Radioisótopos do Iodo , Ligantes , Ovário , Fator de Crescimento Derivado de Plaquetas/metabolismo , Proteínas Recombinantes/metabolismo , Fatores de Tempo
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