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1.
J Perinatol ; 36(2): 157-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26814803

RESUMO

Pneumothorax is usually diagnosed when signs of life-threatening tension pneumothorax develop. The case report describes novel data derived from miniature superficial sensors that continuously monitored the amplitude and symmetry of the chest wall tidal displacement (TDi) in a premature infant that suffered from pneumothorax. Off-line analysis of the TDi revealed slowly progressing asymmetric ventilation that could be detected 38 min before the diagnosis was made. The TDi provides novel and valuable information that can assist in early detection and decision making.


Assuntos
Ventilação de Alta Frequência , Recém-Nascido Prematuro , Pneumotórax , Diagnóstico Precoce , Desenho de Equipamento , Ventilação de Alta Frequência/efeitos adversos , Ventilação de Alta Frequência/métodos , Humanos , Recém-Nascido , Masculino , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Pneumotórax/diagnóstico , Pneumotórax/fisiopatologia , Pneumotórax/terapia , Testes de Função Respiratória/instrumentação , Testes de Função Respiratória/métodos , Mecânica Respiratória
2.
J Perinatol ; 36(2): 116-20, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26583946

RESUMO

OBJECTIVE: Existing respiratory rate (RR) monitors suffer from inaccuracy. The study assesses the accuracy of a novel modality that monitors lung ventilation with miniature motion sensors. STUDY DESIGN: RR was measured by three methods: impedance technology, motion sensors and visual count, in babies (n=9) that breathed spontaneously or with respiratory support and babies (n=12) that received high-frequency oscillatory ventilation (HFOV). RESULTS: A line close to equality (slope=0.96, r(2)=0.83) was obtained between the motion sensor and the visual count of the RR with narrow 95% limits of agreements (<14.0 b.p.m.). The relationship between the impedance and the visual count showed a lower correlation (r(2)=0.65) and wider 95% limits of agreements (21.4 b.p.m.). The motion sensor- and the ventilator-determined RRs demonstrated a good agreement during HFOV, whereas the impedance failed to measure the RR during HFOV. CONCLUSION: Monitoring RR with motion sensors is more accurate compared with the impedance, in infants, in all ventilation modes.


Assuntos
Eletrodiagnóstico/métodos , Ventilação de Alta Frequência/métodos , Recém-Nascido Prematuro , Monitorização Fisiológica/métodos , Síndrome do Desconforto Respiratório do Recém-Nascido/diagnóstico , Taxa Respiratória , Equipamentos para Diagnóstico , Precisão da Medição Dimensional , Impedância Elétrica , Desenho de Equipamento , Feminino , Humanos , Recém-Nascido , Masculino , Reprodutibilidade dos Testes , Síndrome do Desconforto Respiratório do Recém-Nascido/fisiopatologia , Síndrome do Desconforto Respiratório do Recém-Nascido/terapia
3.
Cell Death Dis ; 4: e791, 2013 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-24008735

RESUMO

Gemcitabine is a chemotherapeutic that is widely used for the treatment of a variety of haematological malignancies and has become the standard chemotherapy for the treatment of advanced pancreatic cancer. Combinational gemcitabine regimes (e.g.with doxorubicin) are being tested in clinical trials to treat a variety of cancers, including colon cancer. The limited success of these trials has prompted us to pursue a better understanding of gemcitabine's mechanism of cell killing, which could dramatically improve the therapeutic potential of this agent. For comparison, we included gamma irradiation that triggers robust cell cycle arrest and Cr(VI), which is a highly toxic chemical that induces a robust p53-dependent apoptotic response. Gemcitabine induced a potent p53-dependent apoptosis that correlated with the accumulation of pro-apoptotic proteins such as PUMA and Bax. This is accompanied by a drastic reduction in p2l and 14-3-3σ protein levels, thereby significantly sensitizing the cells to apoptosis. In vitro and in vivo studies demonstrated that gemcitabine required PUMA transcription to instigate an apoptotic programme. This was in contrast to Cr(VI)-induced apoptosis that required Bax and was independent of transcription. An examination of clinical colon and pancreatic cancer tissues shows higher p53, p21, 14-3-3σ and Bax expression compared with matched normal tissues, yet there is a near absence of PUMA protein. This may explain why gemcitabine shows only limited efficacy in the treatment of these cancers. Our results raise the possibility that targeting the Bax-dependent cell death pathway, rather than the PUMA pathway, could result in significantly improved patient outcome and prognosis for these cancers.


Assuntos
Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/genética , Desoxicitidina/análogos & derivados , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , Proteína Supressora de Tumor p53/metabolismo , Proteínas 14-3-3/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Linhagem Celular Tumoral , Cromo/farmacologia , Cromo/uso terapêutico , Inibidor de Quinase Dependente de Ciclina p21/genética , Dano ao DNA , Desoxicitidina/farmacologia , Desoxicitidina/uso terapêutico , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Camundongos , Camundongos SCID , Modelos Biológicos , Biossíntese de Proteínas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Indução de Remissão , Transcrição Gênica/efeitos dos fármacos , Proteína X Associada a bcl-2/metabolismo , Gencitabina
4.
J Perinatol ; 33(6): 490-1, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23719252

RESUMO

We present a case of a female neonate who had a nonimmune hydrops fetalis and severe hemolytic anemia due to a rare combination of glucose-6-phosphate dehydrogenase (G6PD) deficiency and congenital dyserythropoietic anemia. We conclude that in severe cases with persistent anemia one should search after delivery for a second reason other than G6PD deficiency alone.


Assuntos
Anemia Diseritropoética Congênita/diagnóstico , Deficiência de Glucosefosfato Desidrogenase/diagnóstico , Hidropisia Fetal/diagnóstico , Hidropisia Fetal/etiologia , Anemia Diseritropoética Congênita/terapia , Biópsia por Agulha , Medula Óssea/patologia , Cesárea , Diagnóstico Diferencial , Células Precursoras Eritroides/patologia , Transfusão Total , Feminino , Deficiência de Glucosefosfato Desidrogenase/terapia , Hematócrito , Humanos , Hidropisia Fetal/terapia , Lactente , Recém-Nascido , Icterícia Neonatal/diagnóstico , Icterícia Neonatal/etiologia , Icterícia Neonatal/terapia , Microscopia Eletrônica , Fototerapia , Gravidez
6.
Ultrasound Obstet Gynecol ; 27(3): 290-5, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16302282

RESUMO

OBJECTIVE: To determine whether Down syndrome can be detected by combining measurements of fetal nasal bone (NB) length, prenasal thickness (PT) and digits 2 and 3 of the hand. METHODS: Two hundred and fifty-four normal and 25 Down-syndrome fetuses were scanned between 15 and 33 weeks' gestation. Physicians performing the scans were not blinded to the fetal karyotype. Both PT and NB were measured in a mid-sagittal plane. For PT measurement calipers were placed between the frontonasal angle and the outer skin edge. Digits 2 and 3 of one hand were also measured. The results (except for PT/NB ratio) were expressed in multiples of the normal gestation-specific median (MoM). A logistic regression model was used to estimate the odds of the fetus having Down syndrome given different combinations of NB, PT, PT/NB ratio, and digits 2 and 3 measurements. The odds were used to calculate the risk of Down syndrome for each pregnant woman from her age and measurements. RESULTS: The median PT MoM for unaffected fetuses and Down-syndrome fetuses was 1.12 vs. 1.35 (P < 0.0001). The median NB MoM for unaffected and Down-syndrome fetuses was 1.03 vs. 0.81 (P < 0.001) and the PT/NB ratio MoM for unaffected and Down-syndrome fetuses was 0.63 vs. 0.96 (P < 0.001). The respective median MoM values for digits 2 and 3 of the Down-syndrome fetuses were significantly smaller (0.81 vs. 0.93 and 0.89 vs. 0.95, respectively, P = 0.003). Only the PT/NB ratio and digit 2 were finally included in the logistic regression equation. Using a 1 in 200 risk cut-off, the observed sensitivity and false-positive rate were 76% and 6.7%, respectively. CONCLUSION: Combining the PT/NB ratio and digit 2 measurements yielded a promising screening detection rate. Confirmation of our findings in a prospective study is needed before the method can be used clinically.


Assuntos
Síndrome de Down/diagnóstico por imagem , Dedos/embriologia , Osso Nasal/embriologia , Adulto , Biometria , Estudos Transversais , Feminino , Dedos/diagnóstico por imagem , Idade Gestacional , Humanos , Osso Nasal/diagnóstico por imagem , Variações Dependentes do Observador , Gravidez , Segundo Trimestre da Gravidez , Estudos Prospectivos , Ultrassonografia
8.
Biochemistry ; 40(44): 13246-53, 2001 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-11683633

RESUMO

Tumor or tumor-associated cells cleave circulating plasminogen into three or four kringle-containing antiangiogenic fragments, collectively referred to as angiostatin. Angiostatin blocks tumor growth and metastasis by preventing the growth of endothelial cells that are critical for tumor vascularization. Here, we show that cancer and normal cells convert plasminogen into a novel 22 kDa fragment (p22). Production of this plasminogen fragment in a cell-free system has allowed characterization of the structure and activity of the protein. p22 consists of amino acid residues 78-180 of plasminogen and therefore embodies the first plasminogen kringle (residues 84-162) as well as additional N- and C-terminal residues. Circular dichroism and intrinsic fluorescence spectrum analysis have defined structural differences between p22 and recombinant plasminogen kringle 1 (rK1), therefore suggesting a unique conformation for kringle 1 within p22. Proliferation of capillary endothelial cells but not cells of other lineages was selectively inhibited by p22 in vitro. In addition, p22 prevented vascular growth of chick chorioallantoic membranes (CAMs) in vivo. Furthermore, administration of p22 at low dose suppressed the growth of murine Lewis lung carcinoma (LLC) metastatic foci in vivo. This is the first identification of a single kringle-containing antiangiogenic plasminogen fragment produced under physiological conditions.


Assuntos
Inibidores da Angiogênese/farmacologia , Fragmentos de Peptídeos/farmacologia , Plasminogênio/farmacologia , Alantoide/efeitos dos fármacos , Sequência de Aminoácidos , Inibidores da Angiogênese/química , Animais , Western Blotting , Carcinoma Pulmonar de Lewis/prevenção & controle , Embrião de Galinha , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Endotélio Vascular/efeitos dos fármacos , Fibrinolisina/metabolismo , Humanos , Técnicas In Vitro , Kringles , Neoplasias Pulmonares/prevenção & controle , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Neovascularização Patológica/prevenção & controle , Fragmentos de Peptídeos/química , Plasminogênio/química
10.
Arch Dis Child Fetal Neonatal Ed ; 85(1): F13-7, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11420315

RESUMO

AIM: To examine the relation between grade III-IV periventricular/intraventricular haemorrhage (PVH/IVH) and antenatal exposure to tocolytic treatment in very low birthweight (VLBW) premature infants. STUDY DESIGN: The study population consisted of 2794 infants from the Israel National VLBW Infant Database, of gestational age 24-32 weeks, who had a cranial ultrasound examination during the first 28 days of life. Infants of mothers with pregnancy induced hypertension or those exposed to more than one tocolytic drug were excluded. Of the 2794 infants, 2013 (72%) had not been exposed to tocolysis and 781 (28%) had been exposed to a single tocolytic agent. To evaluate the effect of tocolysis and confounding variables on grade III-IV PVH/IVH, the chi(2) test, univariate analysis, and a logistic regression model were used. RESULTS: Of the 781 infants (28%) exposed to tocolysis, 341 (12.2%) were exposed to magnesium sulphate, 263 (9.4%) to ritodrine, and 177 (6.3%) to indomethacin. The overall incidence of grade III-IV PVH/IVH was 13.4%. In the multivariate logistic regression analysis, the following factors were related significantly and independently to grade III-IV PVH/IVH: no prenatal steroid treatment, low gestational age, one minute Apgar score 0-3, respiratory distress syndrome, patent ductus arteriosus, mechanical ventilation, and pneumothorax. Infants exposed to ritodrine tocolysis (but not to the other tocolytic drugs) were at significantly lower risk of grade III-IV PVH/IVH after adjustment for other variables (odds ratio = 0.3; 95% confidence interval 0.2 to 0.6). CONCLUSION: This study suggests that antenatal exposure of VLBW infants to ritodrine tocolysis, in contrast with tocolysis induced by magnesium sulphate or indomethacin, was associated with a lower incidence of grade III-IV PVH/IVH.


Assuntos
Recém-Nascido de muito Baixo Peso , Hemorragias Intracranianas/induzido quimicamente , Efeitos Tardios da Exposição Pré-Natal , Tocolíticos/efeitos adversos , Anti-Inflamatórios/uso terapêutico , Índice de Apgar , Permeabilidade do Canal Arterial/complicações , Feminino , Idade Gestacional , Humanos , Indometacina/efeitos adversos , Recém-Nascido , Modelos Logísticos , Sulfato de Magnésio/efeitos adversos , Análise Multivariada , Pneumotórax/complicações , Gravidez , Respiração Artificial , Síndrome do Desconforto Respiratório do Recém-Nascido/complicações , Fatores de Risco , Ritodrina/efeitos adversos , Esteroides
11.
J Biol Chem ; 276(27): 25212-21, 2001 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-11319229

RESUMO

In a previous report we showed that plasmin-dependent lysis of a fibrin polymer, produced from purified components, was totally blocked if annexin II heterotetramer (AIIt) was present during fibrin polymer formation. Here, we show that AIIt inhibits fibrin clot lysis by stimulation of plasmin autodegradation, which results in a loss of plasmin activity. Furthermore, the C-terminal lysine residues of its p11 subunit play an essential role in the inhibition of fibrin clot lysis by AIIt. We also found that AIIt binds to fibrin with a K(d) of 436 nm and a stoichiometry of about 0.28 mol of AIIt/mol of fibrin monomer. The binding of AIIt to fibrin was not dependent on the C-terminal lysines of the p11 subunit. Furthermore, in the presence of plasminogen, the binding of AIIt to fibrin was increased to about 1.3 mol of AIIt/mol of fibrin monomer, suggesting that AIIt and plasminogen do not compete for identical sites on fibrin. Immunohistochemical identification of p36 and p11 subunits of AIIt in a pathological clot provides important evidence for its role as a physiological fibrinolytic regulator. These results suggest that AIIt may play a key role in the regulation of plasmin activity on the fibrin clot surface.


Assuntos
Anexina A2/farmacologia , Fibrina/metabolismo , Fibrinolisina/metabolismo , Fibrinólise , Animais , Bovinos , Glicerol/farmacologia , Humanos , Imuno-Histoquímica , Cinética , Pulmão/patologia , Conformação Proteica
12.
J Biol Chem ; 276(12): 8924-33, 2001 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-11114303

RESUMO

Plasmin, a broad spectrum proteinase, is inactivated by an autoproteolytic reaction that results in the destruction of the heavy and light chains of the protein. Recently we demonstrated that a 61-kDa plasmin fragment was one of the major products of this autoproteolytic reaction (Fitzpatrick, S. L., Kassam, G., Choi, K. S., Kang, H. M., Fogg, D. K., and Waisman, D. M. (2000)Biochemistry 39, 1021-1028). In the present communication we have identified the 61-kDa plasmin fragment as a novel four kringle-containing protein consisting of the amino acid sequence Lys(78)-Lys(468). To avoid confusion with the plasmin(ogen) fragment, angiostatin(R) (Lys(78)-Ala(440)), we have named this protein A(61). Unlike angiostatin, A(61) was produced in vitro from plasmin autodigestion in the absence of sulfhydryl donors. A(61) bound to lysine-Sepharose and also underwent a large increase in fluorescence yield upon binding of the lysine analogue, trans-4-aminomethylcyclohexanecarboxylic acid. Circular dichroism suggested that A(61) was composed of 21% beta-strand, 14% beta-turn, 18% 3(1)-helix and 8% 3(10)-helix. A(61) was an anti-angiogenic protein as indicated by the inhibition of bovine capillary endothelial cell proliferation. Plasminogen was converted to A(61) by HT1080 cells and bovine capillary endothelial cells. Furthermore, a plasminogen fragment similar to A(61) was present in the serum of humans as well as normal and tumor-bearing mice. These results establish that plasmin turnover can generate anti-angiogenic plasmin fragments in a nonpathological setting.


Assuntos
Fibrinolisina/metabolismo , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/isolamento & purificação , Plasminogênio/química , Plasminogênio/isolamento & purificação , Compostos de Sulfidrila/metabolismo , Angiostatinas , Animais , Eletroforese em Gel de Poliacrilamida , Humanos , Hidrólise , Camundongos , Camundongos Endogâmicos C57BL , Células Tumorais Cultivadas
13.
J Biol Chem ; 276(7): 5310-5, 2001 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-11067857

RESUMO

Annexin II heterotetramer (AIIt) is a multifunctional Ca(2+)-binding protein composed of two 11-kDa subunits and two annexin II subunits. The annexin II subunit contains the binding sites for anionic phospholipids, heparin, and F-actin, whereas the p11 subunit provides a regulatory function. The F-actin-binding site is presently unknown. In the present study we have utilized site-directed mutagenesis to create annexin II mutants with truncations in the C terminus of the molecule. Interestingly, a mutant annexin II lacking its C-terminal 16, 13, or 9 amino acids was unable to bind to F-actin but still retained its ability to interact with both anionic phospholipids and heparin. Recombinant AIIt, composed of wild-type p11 subunits and the mutant annexin II subunits, was also unable to bundle F-actin. This loss of F-actin bundling activity was directly attributable to the inability of mutant AIIt to bind F-actin. These results establish for the first time that the annexin II C-terminal amino acid residues, LLYLCGGDD, participate in F-actin binding.


Assuntos
Actinas/metabolismo , Anexina A2/química , Anexina A2/metabolismo , Motivos de Aminoácidos , Animais , Anexina A2/genética , Sítios de Ligação , Cinética , Mutagênese Sítio-Dirigida , Mutação , Fosfolipídeos/metabolismo
14.
J Biol Chem ; 275(49): 38877-84, 2000 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-10980196

RESUMO

Annexin II heterotetramer (AIIt) is a multifunctional Ca(2+)-binding protein composed of two 11-kDa subunits and two annexin II subunits. The annexin II subunit contains three type II and two type III Ca(2+)-binding sites which are thought to regulate the interaction of AIIt with anionic phospholipid, F-actin, and heparin. In the present study we utilized site-directed mutagenesis to create AIIt mutants with inactive type III (TM AIIt), type II (CM AIIt), and both type II and III Ca(2+)-binding sites (TCM AIIt). Surprisingly, we found that in the presence of Ca(2+), the TM, CM, and TCM AIIt bound phospholipid and F-actin with similar affinity to the wild type AIIt (WT AIIt). Furthermore, the TCM mutant, and to a lesser extent the TM and CM AIIt displayed dose-dependent Ca(2+)-independent phospholipid aggregation and binding. While the TM and CM AIIt demonstrated Ca(2+)-dependent binding to F-actin, the binding of the TCM AIIt was Ca(2+)-independent. These results suggest that the type II or type III Ca(2+)-binding sites do not directly participate in anionic phospholipid or F-actin binding. We therefore propose that in the absence of Ca(2+), the type II and type III Ca(2+)-binding sites of AIIt stabilize a conformation of AIIt that is unfavorable for binding phospholipid and F-actin. Ca(2+) binding to these sites, or the inactivation of these Ca(2+)-binding sites by site-directed mutagenesis, results in a conformational change that promotes binding to anionic phospholipid and F-actin. Since the TM, CM, and TCM AIIt require Ca(2+) for binding to heparin, we also propose that novel Ca(2+)-binding sites regulate this binding event.


Assuntos
Actinas/metabolismo , Anexina A2/química , Anexina A2/metabolismo , Cálcio/metabolismo , Substituição de Aminoácidos , Sítios de Ligação , Humanos , Cinética , Lipossomos/química , Lipossomos/metabolismo , Substâncias Macromoleculares , Mutagênese Sítio-Dirigida , Fosfolipídeos/metabolismo , Subunidades Proteicas , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo
15.
J Biol Chem ; 275(17): 12806-12, 2000 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-10777578

RESUMO

To study potential roles of plasma membrane-associated extracellular cathepsin B in tumor cell invasion and metastasis, we used the yeast two-hybrid system to screen for proteins that interact with human procathepsin B. The annexin II light chain (p11), one of the two subunits of the annexin II tetramer, was one of the proteins identified. We have confirmed that recombinant human procathepsin B interacts with p11 as well as with the annexin II tetramer in vitro. Furthermore, procathepsin B could interact with the annexin II tetramer in vivo as demonstrated by coimmunoprecipitation. Cathepsin B and the annexin II tetramer were shown by immunofluorescent staining to colocalize on the surface of human breast carcinoma and glioma cells. Taken together, our results indicate that the annexin II tetramer can serve as a binding protein for procathepsin B on the surface of tumor cells, an interaction that may facilitate tumor invasion and metastasis.


Assuntos
Anexina A2/metabolismo , Catepsina B/metabolismo , Precursores Enzimáticos/metabolismo , Anexina A2/química , Membrana Celular/metabolismo , DNA Complementar/metabolismo , Biblioteca Gênica , Glutationa Transferase/metabolismo , Humanos , Immunoblotting , Imuno-Histoquímica , Proteínas de Membrana/metabolismo , Microscopia Confocal , Mutagênese , Plasmídeos/metabolismo , Testes de Precipitina , Ligação Proteica , Conformação Proteica , Proteínas Recombinantes de Fusão , Células Tumorais Cultivadas , Técnicas do Sistema de Duplo-Híbrido
16.
Biochemistry ; 39(9): 2140-8, 2000 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-10694379

RESUMO

Fucoidan, a sulfated fucopolysaccharide, mimics the fucosylated glycans of glycoproteins and has therefore been used as a probe for investigating the role of membrane polysaccharides in cell-cell adhesion. In the present report we have characterized the interaction of fucoidan with the Ca(2+)- and phospholipid-binding protein annexin II tetramer (AIIt). AIIt bound to fucoidan with an apparent K(d) of 1.24 +/- 0.69 nM (mean +/- SD, n = 3) with a stoichiometry of 0.010 +/- 0.001 mol of fucoidan/mol of AIIt (mean +/- SD, n = 3). The binding of fucoidan to AIIt was Ca(2+)-independent. Furthermore, in the presence but not the absence of Ca(2+), the binding of fucoidan to AIIt caused a decrease in the alpha-helical content from 32% to 7%. A peptide corresponding to a region of the p36 subunit of AIIt, F(306)-S(313), which contains a Cardin-Weintraub consensus sequence for heparin binding, was shown to undergo a conformational change upon fucoidan binding. This suggests that heparin and fucoidan bound to this region of AIIt. The binding of fucoidan but not heparin by AIIt also inhibited the ability of AIIt to bind to and aggregate phospholipid liposomes. These results suggest that the binding of AIIt to the carbohydrate conjugates of certain membrane glycoproteins may have profound effects on the structure and biological activity of AIIt.


Assuntos
Anexina A2/química , Polissacarídeos/química , Sequência de Aminoácidos , Anexina A2/antagonistas & inibidores , Anexina A2/metabolismo , Sítios de Ligação , Cálcio/química , Dicroísmo Circular , Relação Dose-Resposta a Droga , Fucose/química , Heparina/química , Lipossomos/antagonistas & inibidores , Lipossomos/química , Dados de Sequência Molecular , Polissacarídeos/metabolismo , Polissacarídeos/farmacologia , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Alga Marinha , Ésteres do Ácido Sulfúrico/química
17.
Biochim Biophys Acta ; 1477(1-2): 215-30, 2000 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-10708859

RESUMO

The cysteine protease cathepsin B is upregulated in a variety of tumors, particularly at the invasive edges. Cathepsin B can degrade extracellular matrix proteins, such as collagen IV and laminin, and can activate the precursor form of urokinase plasminogen activator (uPA), perhaps thereby initiating an extracellular proteolytic cascade. Recently, we demonstrated that procathepsin B interacts with the annexin II heterotetramer (AIIt) on the surface of tumor cells. AIIt had previously been shown to interact with the serine proteases: plasminogen/plasmin and tissue-type plasminogen activator (tPA). The AIIt binding site for cathepsin B differs from that for either plasminogen/plasmin or tPA. AIIt also interacts with extracellular matrix proteins, e.g., collagen I and tenascin-C, forming a structural link between the tumor cell surface and the extracellular matrix. Interestingly, cathepsin B, plasminogen/plasmin, t-PA and tenascin-C have all been linked to tumor development. We speculate that colocalization through AIIt of proteases and their substrates on the tumor cell surface may facilitate: (1) activation of precursor forms of proteases and initiation of proteolytic cascades; and (2) selective degradation of extracellular matrix proteins. The recruitment of proteases to specific regions on the cell surface, regions where potential substrates are also bound, could well function as a 'proteolytic center' to enhance tumor cell detachment, invasion and motility.


Assuntos
Anexina A2/metabolismo , Catepsina B/metabolismo , Proteínas de Membrana/metabolismo , Neoplasias/metabolismo , Animais , Anexina A2/química , Catepsina B/química , Proteínas da Matriz Extracelular/metabolismo , Humanos , Metástase Neoplásica , Células Tumorais Cultivadas , Regulação para Cima
18.
Biochemistry ; 39(5): 1021-8, 2000 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-10653646

RESUMO

Annexin II tetramer (AIIt) is a major Ca(2+)-binding protein of the endothelial cell surface which has been shown to stimulate the tissue plasminogen activator (t-PA)-dependent conversion of plasminogen to plasmin. In the present report, we have examined the regulation of plasmin activity by AIIt. The incubation of plasmin with AIIt resulted in a 95% loss in plasmin activity. SDS-PAGE analysis established that AIIt stimulated the autoproteolytic digestion of plasmin heavy and light chains. The kinetics of AIIt-stimulated plasmin autoproteolysis were first-order, suggesting that binding of plasmin to AIIt resulted in the spontaneous autoproteolysis of the bound plasmin. AIIt did not affect the activity of other serine proteases such as t-PA or urokinase-type plasminogen activator. Furthermore, other annexins such as annexin I, II, V, or VI did not stimulate plasmin autoproteolysis. Increasing the concentration of AIIt on the surface of human 293 epithelial cells increased cell-mediated plasmin autoproteolysis. Thus, in addition to stimulating the formation of plasmin, AIIt also promotes plasmin inactivation. These results therefore suggest that AIIt may function to provide the cell surface with a transient pulse of plasmin activity.


Assuntos
Anexina A2/fisiologia , Fibrinolisina/antagonistas & inibidores , Fibrinolisina/metabolismo , Animais , Anexina A2/química , Bovinos , Linhagem Celular , Membrana Celular/enzimologia , Relação Dose-Resposta a Droga , Ativação Enzimática , Inibidores Enzimáticos/química , Humanos , Hidrólise , Rim/citologia , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/metabolismo , Plasminogênio/metabolismo , Especificidade por Substrato , Ativador de Plasminogênio Tecidual/metabolismo
19.
Trends Cardiovasc Med ; 9(3-4): 92-102, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10578524

RESUMO

The enzymatic cascade triggered by activation of plasminogen has been implicated in a variety of normal and pathologic events, such as fibrinolysis, wound healing, tissue remodeling, embryogenesis, and the invasion and spread of transformed tumor cells. Recent data established that the Ca(2+)- and phospholipid-binding protein, annexin II heterotetramer (AIIt) binds tissue-type plasminogen activator (tPA), plasminogen, and plasmin, and dramatically stimulates the tPA-dependent conversion of plasminogen to plasmin in vitro. Interestingly, the binding of plasmin to AIIt can inhibit the activity of the enzyme, suggesting that plasmin bound to the cell surface is regulated by AIIt. The existing experimental evidence suggests that AIIt is the key physiological receptor for plasminogen on the extracellular surface of endothelial cells.


Assuntos
Anexina A2/fisiologia , Plasminogênio/metabolismo , Animais , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Fibrinolisina/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores de Ativador de Plasminogênio Tipo Uroquinase , Ativador de Plasminogênio Tecidual/metabolismo
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