Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
1.
Clin Oncol (R Coll Radiol) ; 30(10): 625-633, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30196845

RESUMO

AIMS: Emerging evidence suggests that contact X-ray brachytherapy (CXB) may increase the clinical complete response rate and durability when administered after standard chemoradiotherapy in patients with rectal cancer. The addition of CXB in partial responders is therefore probably cost-effective. The affordability of widening access to CXB in the UK, however, has not been evaluated. MATERIALS AND METHODS: Decision analytical modelling with Monte Carlo simulation was used to evaluate long-term costs for the management of patients with rectal cancers who were given a CXB boost when a clinical complete response was not initially achieved following chemoradiotherapy in order to facilitate a watch and wait approach. A third-party payer (National Health Service) perspective was adopted, probabilistic sensitivity analysis was carried out and a scenario analysis was performed to investigate the effect of the number of referral centres and number of patients treated with CXB. RESULTS: We estimate that 818 (95% confidence interval 628-1021) patients per year are eligible for CXB as an adjunct to a watch and wait approach in England and Wales. As this management is less costly than surgical management for each individual patient, the more patients treated, the more affordable the technology. Even if as few as 125 patients are treated nationally in 15 centres, the cost of implementing this technology would be less than £4 million. If the average number of patients treated in each centre is 30, this technology would be cost saving within 5 years. CONCLUSIONS: The cost of CXB is not prohibitive according to the National Institute for Health and Care Excellence threshold for implementation of new technology and may even be cost saving within 5 years compared with standard surgical management, depending on the uptake of the technology and the number of referral centres.


Assuntos
Braquiterapia/economia , Braquiterapia/métodos , Custos de Cuidados de Saúde , Neoplasias Retais/economia , Neoplasias Retais/radioterapia , Quimiorradioterapia , Redução de Custos , Análise Custo-Benefício , Inglaterra , Humanos , Neoplasias Retais/terapia , País de Gales , Conduta Expectante , Raios X
2.
Clin Oncol (R Coll Radiol) ; 30(3): 166-177, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29248311

RESUMO

AIMS: Following chemoradiotherapy in patients with rectal cancer, the addition of contact X-ray brachytherapy (CXB) in partial responders might increase the proportion of patients with a clinical complete response (cCR) and who are thus suitable for watch and wait management. However, the long-term cost-effectiveness of this approach has not been evaluated. MATERIALS AND METHODS: Decision analytical modelling and a Markov simulation were used to compare long-term costs, quality-adjusted life years (QALYs) and cost-effectiveness from a third-party payer (National Health Service) perspective for treatment strategies after chemoradiotherapy; watch and wait with CXB when a cCR was not initially achieved after external beam radiotherapy (EBRT) (WWCXB), watch and wait with EBRT alone (WWEBRT) and radical surgery for all patients. The effect of uncertainty in model parameters and patient demographics was investigated. RESULTS: WWCXB had a higher QALY payoff than both radical surgery and WWEBRT and was less costly in most scenarios and demographic cohorts. In all plausible scenarios, WWCXB was the most cost-effective, at a threshold of £20 000/QALY. This finding was insensitive to uncertainty associated with model parameters. CONCLUSIONS: WWCXB is likely to be cost-effective compared with both WWEBRT alone and radical surgery. These findings support the use of CXB boost as an adjunct to a watch and wait strategy.


Assuntos
Braquiterapia/economia , Neoplasias Retais/economia , Neoplasias Retais/radioterapia , Conduta Expectante/economia , Quimiorradioterapia , Análise Custo-Benefício , Feminino , Humanos , Pessoa de Meia-Idade , Anos de Vida Ajustados por Qualidade de Vida , Neoplasias Retais/tratamento farmacológico
3.
Mucosal Immunol ; 3(6): 633-44, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20664576

RESUMO

Tumor necrosis factor α (TNFα) is a key pathogenic factor in Crohn's disease and rheumatoid arthritis. TNF(ΔARE) mice express high levels of TNFα and present Crohn's-like ileitis and arthritis. Alterations in the chemokine network could underline the TNF-driven ileitis. The aim of this study was to evaluate the role of TNF and chemokines in ileitis using ectromelia virus cytokine response modifier D (CrmD), a protein that binds TNFα and a limited number of chemokines. We generated transgenic mice expressing CrmD in intestinal epithelial cells (vCrmD mice) and crossed them with the TNF(ΔARE) mice to test whether CrmD could affect TNF-driven inflammatory processes. During homeostasis, only the number of B cells in the lamina propria was reduced by CrmD expression. Interestingly, CrmD expression in the intestine markedly attenuated the inflammatory infiltrates in the ileum of TNF(ΔARE) mice, but did not affect development of arthritis. Our results suggest that CrmD affects development of ileitis by locally affecting both TNF and chemokine function in the ileum.


Assuntos
Linfócitos B/metabolismo , Doença de Crohn/imunologia , Vírus da Ectromelia/imunologia , Mucosa Intestinal/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Febre Reumática/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Virais/metabolismo , Animais , Artrite , Linfócitos B/imunologia , Linfócitos B/patologia , Proteínas de Transporte/genética , Proteínas de Transporte/imunologia , Proteínas de Transporte/metabolismo , Células Cultivadas , Doença de Crohn/genética , Doença de Crohn/patologia , Doença de Crohn/fisiopatologia , Modelos Animais de Doenças , Humanos , Ileíte , Inflamação , Mucosa Intestinal/imunologia , Mucosa Intestinal/patologia , Camundongos , Camundongos Mutantes , Camundongos Transgênicos , Mutação/genética , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/imunologia , Febre Reumática/genética , Febre Reumática/patologia , Febre Reumática/fisiopatologia , Transgenes/genética , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Proteínas Virais/genética , Proteínas Virais/imunologia
4.
Transplant Proc ; 40(4): 891-4, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18555073

RESUMO

BACKGROUND: A safe and effective preservation solution is a precondition for successful orthotopic liver transplantation (OLT). This study compared University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) solutions in OLT. PATIENTS AND METHODS: We retrospectively reviewed the medical records of 137 primary cadaveric. OLT performed between January 2003 and December 2006 at our institution. Sixty-eight grafts were harvested using UW and 69 using HTK. Recipients were managed similarly in regard to operative techniques and immunosuppression. We collected donor data including serum transaminases, serum sodium, ICU stay and assessed macroscopic liver quality. Recipient serum transaminases were collected on postoperative days 1, 7, 14, and 30. We compared biliary and vascular complications, as well as patient and graft survivals. RESULTS: Mean serum bilirubin levels were slightly higher in the HTK group at 1,7,14, and 30 days after transplantation, whereas transaminases were higher in the UW group. Primary nonfunction occurred in 1 patient in each group. Retransplantation was performed in 5 patients in the UW and in 9 patients in the HTK group. Biliary complication rates were similar in the UW and HTK groups (22% and 17%, respectively). Six arterial complications occurred in the HTK (8.7%) and 2 in the UW group (2.9%; P < .05). Mean follow-up was 25 months. Graft survival at 1, 12, and 36 months was 90%, 78%, and 75% versus 90%, 71%, and 71% in the UW versus HTK groups, respectively. One-, 12-, and 36-month patient survival rates were 93%, 78%, and 75% versus 93%, 78%, and 78% in the UW versus HTK groups, respectively. CONCLUSIONS: There were no significant differences in graft and patient survivals between the 2 groups. Whereas the biliary complication rates were comparable in both groups, the arterial complications were clearly higher in the UW group (8.7% vs 2.9%; P < .05%). UW and HTK solutions seemed to be equally safe and effective in the preservation of liver grafts. The high incidence of arterial complications in the UW group requires further prospective studies.


Assuntos
Transplante de Fígado/fisiologia , Soluções para Preservação de Órgãos , Adenosina , Adulto , Idoso , Alopurinol , Feminino , Seguimentos , Glucose , Glutationa , Sobrevivência de Enxerto , Humanos , Insulina , Testes de Função Hepática , Transplante de Fígado/mortalidade , Masculino , Manitol , Prontuários Médicos , Pessoa de Meia-Idade , Cloreto de Potássio , Procaína , Rafinose , Estudos Retrospectivos , Análise de Sobrevida , Fatores de Tempo
5.
Transplant Proc ; 38(10): 3615-9, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17175348

RESUMO

Glycogen storage disease type Ib is a rare metabolic disease caused by a defect of the G6P transporter. Patients suffer from hypoglycemic episodes; growth and developmental delay; osteoporosis; neutropenia; and tendency to infections, ovarian cysts, and liver adenomas. Terminal kidney disease is a rare complication. Liver transplantation has been performed to prevent malignant transformation of hepatic adenomas. We present the case of a female patient with glycogenosis type Ib who had severe hypoglycemic episodes and recurrent infections since early childhood. She became dialysis dependent at the age of 24 years. Kidney transplantation was performed at age 30, and liver transplantation 2 years later. The main indication for liver transplantation were the persistent, therapy-refractory hypoglycemic episodes. The transplanted kidney function is stable. The liver transplantation resulted in the disappearance of hypoglycemic episodes, with the patient leading a normal life and eating a normal diet. The neutropenia did not recover, but there were no more significant infectious episodes after liver transplantation. This is, to the best of our knowledge, the first communication of a dual kidney and liver transplant performed in a patient with glycogenosis type Ib. It confirmed the beneficial effect of liver transplantation on the quality of life of patients with severe hypoglycemia. The transplantation should be attempted earlier in the course of the disease to reduce complications and allow catch-up growth. Hepatocyte transplantation may be considered; however, long-term results seem to be rather poor in the few documented cases.


Assuntos
Doença de Depósito de Glicogênio Tipo I/cirurgia , Transplante de Rim , Transplante de Fígado , Adulto , Biópsia , Feminino , Doença de Depósito de Glicogênio Tipo I/patologia , Doença de Depósito de Glicogênio Tipo I/psicologia , Humanos , Deficiência Intelectual/etiologia , Fígado/patologia , Obesidade/etiologia , Resultado do Tratamento
6.
Clin Exp Allergy ; 33(8): 1118-24, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12911787

RESUMO

BACKGROUND: Leucocyte migration within inflammatory skin compartments in allergic contact dermatitis (ACD) is the result of a sophisticated multi-step event where multiple molecules are involved. OBJECTIVE: Since non-antigen-specific mechanisms have been described as an early participant in elicitation of ACD, we investigated the kinetics of the expression of monocyte chemoattractant protein-1 (MCP-1/CCL2) and the type of infiltrating cells. We compared the time course production of MCP-1/CCL2 with connecting segment-1 (CS-1) fibronectin and thymus and activation-regulated chemokine (TARC/ CCL17) expression. METHODS: Biopsies from 10 individuals challenged in their back with the antigen responsible for their contact dermatitis and an irrelevant antigen were taken at different times and histology, immunohistochemistry for CS-1 fibronectin, TARC/CCL17, CD3, CD68, CXCR3, CCR4 and in situ hybridization for MCP-1/CCL2 were performed. RESULTS: At positive antigen stimulated sites expression of MCP-1/CCL2 by basal keratinocytes and isolated cells in dermis started at 10 h. CS-1 fibronectin and TARC/CCL17 expression by blood endothelial cells was found at 2 and 10 h, respectively. This was followed by dermal accumulation of mononuclear cells with a significant increase of CD3+ and CD68+cells. At 48 h, approximately 58% of infiltrating cells were CXCR3+, and 35% CCR4+. CONCLUSIONS: We showed evidence of the fact that CS-1 fibronectin expression precedes the production of MCP-1/CCL2 and TARC/CCL17 in the skin of patients with ACD, suggesting that these molecules participate in the early complex process of migrating mononuclear cells during elicitation of ACD.


Assuntos
Proteínas de Transporte/biossíntese , Quimiocina CCL2/biossíntese , Dermatite Alérgica de Contato/metabolismo , Oligopeptídeos/biossíntese , Adulto , Idoso , Biópsia , Quimiocina CCL17 , Quimiocina CCL2/genética , Quimiocinas CC/biossíntese , Dermatite Alérgica de Contato/imunologia , Dermatite Alérgica de Contato/patologia , Feminino , Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Hibridização In Situ , Masculino , Pessoa de Meia-Idade , Testes do Emplastro/métodos , RNA Mensageiro/genética , Pele/imunologia , Pele/metabolismo
7.
J Cutan Pathol ; 29(6): 347-53, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12135465

RESUMO

BACKGROUND: Allergic contact dermatitis (ACD) is a common human dermatosis in which not all the mechanisms involved in its pathogenesis have been elucidated. OBJECTIVE: To study the expression of CS-1 fibronectin, TARC and Th1-associated chemokine receptors in biopsies from allergic patch test reactions. MATERIAL AND METHODS: Thirteen patients already diagnosed with ACD were challenged on the back with the antigen responsible of the disease and macroscopic responses and biopsies taken after 48 h. Skin biopsies from negative control challenge sites, AD and ICD were also taken. Samples were fixed, embedded in paraffin wax and processed in order to perform histological and immunohistochemical studies. RESULTS: All subjects with ACD showed a positive clinical response and a perivascular mononuclear cell infiltration at 48 h, which was not seen in the negative controls. The majority of skin-infiltrating cells were CD4+ and CD8+ and up to 54% or 40% of them expressed CXCR3 or CCR5, respectively. We also showed expression of CS-1 fibronectin in inflamed endothelial cells not only in ACD but also in AC and ICD. In contrast TARC was only expressed in ACD and AC. CONCLUSION: We showed for the first time that CS-1 fibronectin is expressed in dermal vessels from allergic patch tests positive reactions, as well as irritant and atopic skin lesions.


Assuntos
Dermatite Alérgica de Contato/metabolismo , Endotélio Vascular/metabolismo , Peptídeos/metabolismo , Adolescente , Adulto , Idoso , Antígenos CD/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Quimiocina CCL17 , Quimiocinas CC/metabolismo , Proteínas de Ligação a DNA/metabolismo , Dermatite Alérgica de Contato/patologia , Endotélio Vascular/patologia , Feminino , Humanos , Técnicas Imunoenzimáticas , Peptídeos e Proteínas de Sinalização Intercelular , Masculino , Pessoa de Meia-Idade , Receptores CCR5/metabolismo , Receptores CXCR3 , Receptores de Quimiocinas/metabolismo , Fatores de Transcrição/metabolismo
9.
Eur J Haematol ; 59(2): 89-99, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9293856

RESUMO

In order to determine the relationships between CD2+ lymphocyte subpopulations and tumour mass, the immunophenotype of natural killer (NK) cells and T lymphocyte subsets was studied in 56 B-chronic lymphocytic leukaemia (B-CLL) patients and 38 healthy subjects. The patients were classified according to their blood lymphocyte count (BLC). Forty patients had BLC<30x10(9)/l (low BLC, less tumour mass) and 16 patients had BLC>30x10(9)/l (high BLC, larger tumour mass). The percentage of CD3- CD56+ cells, as well as of CD8+, CD8+ CD45RO+ and CD3+ CD57+ T subsets in low BLC patients, were higher than those found in high BLC patients. Conversely, the percentages of CD3+ HLA x DR+, CD4+ and CD4+ CD45RO+ lymphocytes were higher in high BLC patients than in low BLC patients. The CD4/CD8 ratio was decreased in low BLC patients while it was increased in high BLC patients and a significant positive correlation was found between their CD4/CD8 ratio and their BLC. We conclude that in low BLC B-CLL patients there is a decreased percentage of activated helper lymphocytes and an increased percentage of NK cells and activated cytotoxic T lymphocytes. These results suggest a role for NK cells, and helper and cytotoxic T lymphocytes in the control of tumour burden in B-CLL patients.


Assuntos
Leucemia Linfocítica Crônica de Células B/patologia , Linfócitos T Citotóxicos/citologia , Adulto , Idoso , Antígenos CD/análise , Relação CD4-CD8 , Feminino , Humanos , Imunofenotipagem , Leucemia Linfocítica Crônica de Células B/imunologia , Ativação Linfocitária , Subpopulações de Linfócitos , Masculino , Pessoa de Meia-Idade
10.
Ann R Australas Coll Dent Surg ; 11: 82-95, 1991 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1844051

RESUMO

Endodontic therapy can be challenging at the diagnostic and technical levels. The more one can advance one's accomplishments, the more that would-be barriers cease to be so. Difficult aspects of tooth isolation and assessment of root integrity can be rendered less problematic by some relatively simple methods. Gaining a clear awareness of the internal layout of a coronal chamber and any possible inclusions can be assisted by use of a modified endodontic explorer. It can be usefully employed to resolve with certainty the common dilemma of whether openings at the base of a molar or maxillary premolar coronal access cavity are exposures in the pulp chamber roof or orifices in the chamber floor. Locating and then gaining full working length entry into partly calcified canals, even when they are not radiographically discernible, remains one of the difficult tasks in endodontic therapy, but methods can be implemented that maximize their successful negotiation and management. The use of fine engine-driven reamers, but absolutely restricted to a reciprocating action handpiece, is described.


Assuntos
Preparo da Cavidade Dentária/instrumentação , Cavidade Pulpar/anatomia & histologia , Tratamento do Canal Radicular/métodos , Raiz Dentária/anatomia & histologia , Preparo da Cavidade Dentária/métodos , Calcificações da Polpa Dentária , Humanos , Odontometria , Radiografia , Tratamento do Canal Radicular/instrumentação , Raiz Dentária/diagnóstico por imagem
12.
Mech Ageing Dev ; 53(2): 157-67, 1990 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-2160571

RESUMO

The proposed study was undertaken to investigate the effect of aging on control of the oxidative phosphorylation pathway. Flux control coefficients for adenine nucleotide translocase and cytochrome c oxidase were determined using the procedure of Groen et al. [J. Biol. Chem., 257 (1982) 137-144]. Hepatic mitochondrial fractions from Fischer 344 rats were isolated from control (average age 6.5 months), and aged (average age 27.3 months) groups. No aging-related changes in the extent of control of respiration by the oxidase were obtained, however, differences were observed for the translocase. For the control group of animals, the greatest regulation occurred at 80-85% maximal respiratory rates, and declined at higher rates. For the aged group, a similar flux control coefficient was obtained at 80-85% respiration, but was maintained as respiration increased to maximal rates. It is proposed that changes in the flux control coefficients at maximal respiratory rates are associated with an aging-related decrease in translocase activity. Evaluation of translocase content revealed no significant differences between the two groups supporting the concept that the decreased activity was not due to decreased content. During the course of these experiments, it also became apparent that there was a significant aging-related decrease in the rate of succinate oxidation providing an adequate supply of ADP was present. No significant changes in respiratory rates, or RCR, were evident at suboptimal concentrations of ADP as reported previously from this laboratory [Vorbeck, M.L. et al., Arch. Biochem. Biophys., 214 (1982) 67-79]. Since similar decreases in respiration were obtained upon addition of an uncoupler, the aging-related changes in respiration are attributed to differences at the level of the electron transport system, including its associated reactions. The aging-related differences in respiratory rates, and extent of control of respiration, were both observed under conditions of maximal stimulation of respiration. This suggests an inability of mitochondria from aged animals to respond to the increased demands of oxidation. Basic to these differences may be the lipid-membrane associated changes seen during aging.


Assuntos
Envelhecimento/metabolismo , Fosforilação Oxidativa , Difosfato de Adenosina/farmacologia , Animais , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Cinética , Microssomos Hepáticos/metabolismo , Translocases Mitocondriais de ADP e ATP/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos Endogâmicos F344
13.
Biochim Biophys Acta ; 821(3): 445-52, 1985 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-2416348

RESUMO

The involvement of Ca2+-activated K+ channels in the regulation of the plasma membrane potential and electrogenic uptake of glycine in SP 2/0-AG14 lymphocytes was investigated using the potentiometric indicator 3,3'-diethylthiodicarbocyanine iodide. The resting membrane potential was estimated to be -57 +/- 6 mV (n = 4), a value similar to that of normal lymphocytes. The magnitude of the membrane potential and the electrogenic uptake of glycine were dependent on the extracellular K+ concentration, [K+]o, and were significantly enhanced by exogenous calcium. The apparent Vmax of Na+-dependent glycine uptake was doubled in the presence of calcium, whereas the K0.5 was not affected. Ouabain had no influence on the membrane potential under the conditions employed. Additional criteria used to demonstrate the presence of Ca2+-activated K+ channels included the following: (1) addition of EGTA to calcium supplemented cells elicited a rapid depolarization of the membrane potential that was dependent on [K+]o; (2) the calmodulin antagonist, trifluoperazine, depolarized the membrane potential in a dose-dependent and saturable manner with an IC50 of 9.4 microM; and (3) cells treated with the Ca2+-activated K+ channel antagonist, quinine, demonstrated an elevated membrane potential and depressed electrogenic glycine uptake. Results from the present study provide evidence for Ca2+-activated K+ channels in SP 2/0-AG14 lymphocytes, and that their involvement regulates the plasma membrane potential and thereby the electrogenic uptake of Na+-dependent amino acids.


Assuntos
Cálcio/farmacologia , Canais Iônicos/fisiologia , Potássio/metabolismo , Animais , Linhagem Celular , Glicina/farmacologia , Canais Iônicos/efeitos dos fármacos , Cinética , Linfócitos , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Plasmocitoma , Quinina/farmacologia , Termodinâmica , Trifluoperazina/farmacologia
14.
J Immunol Methods ; 75(1): 141-8, 1984 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-6096446

RESUMO

A method is described for the binding of a detergent solubilized integral membrane protein to polystyrene immunoassay plates. Addition of Bouin's fluid, a histochemical fixative, to wells of plates containing the detergent solubilized antigen, followed by low speed centrifugation, is sufficient to promote binding of antigen in the presence of Triton X-100 concentrations as high as 1.75%. The binding of antigen is rapid and the entire binding procedure, including removal of fixative and washing of the plates, can be accomplished in less than 15 min. Immunological specificity of the bound antigen is retained. This method has been used to effectively screen hybridoma cultures for specific antibodies.


Assuntos
Ácido Acético , Anticorpos Monoclonais/análise , Ensaio de Imunoadsorção Enzimática , Hibridomas/imunologia , Técnicas Imunoenzimáticas , Proteínas de Membrana/metabolismo , Polietilenoglicóis/farmacologia , Acetatos/farmacologia , Animais , Sítios de Ligação/efeitos dos fármacos , Detergentes , Complexo IV da Cadeia de Transporte de Elétrons/imunologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Fixadores , Formaldeído/farmacologia , Soros Imunes/farmacologia , Fígado/enzimologia , Camundongos , Camundongos Endogâmicos BALB C , Octoxinol , Picratos/farmacologia , Ratos
15.
Biochem Biophys Res Commun ; 115(2): 430-6, 1983 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-6626199

RESUMO

A Na+/Ca2+ exchange activity for Ca2+ efflux has been identified in isolated Ehrlich ascites tumor mitochondria. Further, under conditions favoring cycling of Ca2+ across the mitochondrial inner membrane, extramitochondrial [Ca2+] also was shown to be Na+-dependent. The Na+/Ca2+ exchange showed sigmoidal kinetics with a mean (+/-SD) [Na+] required for half maximal stimulation of Ca2+ efflux of 8.4 +/- 3.8 mM and a Hill coefficient of 1.6. Na+/Ca2+ exchange was very sensitive to inhibition by the Ca2+ antagonist diltiazem (56% inhibition at 7.5 nmoles X mg protein-1) whereas a number of other compounds, including verapamil, nupercaine, and trifluoperazine were less effective in inhibiting Ca2+ efflux. These data demonstrate for the first time the presence of a pathway in tumor mitochondria for unidirectional Ca2+ efflux induced by Na+, and provide a mechanism for regulation of tumor intra- and extramitochondrial [Ca2+]. Results of the present study support the need for further study of intracellular Na+ and its role in regulation of Ca2+ homeostasis in tumor cells.


Assuntos
Cálcio/metabolismo , Carcinoma de Ehrlich/metabolismo , Mitocôndrias/metabolismo , Animais , Carbonil Cianeto p-Trifluormetoxifenil Hidrazona/farmacologia , Linhagem Celular , Dibucaína/farmacologia , Masculino , Camundongos , Sódio/farmacologia , Trifluoperazina/farmacologia , Verapamil/farmacologia
16.
J Biol Chem ; 257(21): 12481-4, 1982 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-6182140

RESUMO

The addition of chlortetracycline (CTC) to succinate-energized rat liver mitochondria resulted in depolarization of the membrane potential and decreased respiratory control. CTC inhibited both processes at concentrations that were half maximally effective at approximately 13 and 16 microM, respectively. These inhibitory effects were prevented by either the Ca2+ chelator, ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, or the inhibitor of mitochondrial Ca2+ influx, ruthenium red. These findings are consistent with the formation of a membrane associated calcium-CTC complex and suggest that CTC can alter mitochondrial energy metabolism during transmembrane Ca2+ cycling.


Assuntos
Cálcio/farmacologia , Clortetraciclina/farmacologia , Membranas Intracelulares/fisiologia , Mitocôndrias Hepáticas/fisiologia , Difosfato de Adenosina/farmacologia , Animais , Ácido Egtázico/farmacologia , Membranas Intracelulares/efeitos dos fármacos , Masculino , Potenciais da Membrana/efeitos dos fármacos , Mitocôndrias Hepáticas/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Potenciometria , Ratos , Ratos Endogâmicos , Rutênio Vermelho/farmacologia , Succinatos/farmacologia , Ácido Succínico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA