RESUMO
BACKGROUND: Recent advances are enabling delivery of precision genomic medicine to cancer clinics. While the majority of approaches profile panels of selected genes or hotspot regions, comprehensive data provided by whole-genome and transcriptome sequencing and analysis (WGTA) present an opportunity to align a much larger proportion of patients to therapies. PATIENTS AND METHODS: Samples from 570 patients with advanced or metastatic cancer of diverse types enrolled in the Personalized OncoGenomics (POG) program underwent WGTA. DNA-based data, including mutations, copy number and mutation signatures, were combined with RNA-based data, including gene expression and fusions, to generate comprehensive WGTA profiles. A multidisciplinary molecular tumour board used WGTA profiles to identify and prioritize clinically actionable alterations and inform therapy. Patient responses to WGTA-informed therapies were collected. RESULTS: Clinically actionable targets were identified for 83% of patients, of which 37% of patients received WGTA-informed treatments. RNA expression data were particularly informative, contributing to 67% of WGTA-informed treatments; 25% of treatments were informed by RNA expression alone. Of a total 248 WGTA-informed treatments, 46% resulted in clinical benefit. RNA expression data were comparable to DNA-based mutation and copy number data in aligning to clinically beneficial treatments. Genome signatures also guided therapeutics including platinum, poly-ADP ribose polymerase inhibitors and immunotherapies. Patients accessed WGTA-informed treatments through clinical trials (19%), off-label use (35%) and as standard therapies (46%) including those which would not otherwise have been the next choice of therapy, demonstrating the utility of genomic information to direct use of chemotherapies as well as targeted therapies. CONCLUSIONS: Integrating RNA expression and genome data illuminated treatment options that resulted in 46% of treated patients experiencing positive clinical benefit, supporting the use of comprehensive WGTA profiling in clinical cancer care.
Assuntos
Neoplasias , Perfilação da Expressão Gênica , Genômica/métodos , Humanos , Mutação , Neoplasias/tratamento farmacológico , Neoplasias/genética , Medicina de Precisão/métodos , RNA , TranscriptomaRESUMO
The study of a desmoglein 2 murine model of arrhythmogenic cardiomyopathy revealed cardiac inflammation as a key early event leading to fibrosis. Arrhythmogenic cardiomyopathy (AC) is an inherited heart muscle disorder leading to ventricular arrhythmias and heart failure due to abnormalities in the cardiac desmosome. We examined how loss of desmoglein 2 (Dsg2) in the young murine heart leads to development of AC. Apoptosis was an early cellular phenotype, and RNA sequencing analysis revealed early activation of inflammatory-associated pathways in Dsg2-null (Dsg2-/-) hearts at postnatal day 14 (2 weeks) that were absent in the fibrotic heart of adult mice (10 weeks). This included upregulation of iRhom2/ADAM17 and its associated pro-inflammatory cytokines and receptors such as TNFα, IL6R and IL-6. Furthermore, genes linked to specific macrophage populations were also upregulated. This suggests cardiomyocyte stress triggers an early immune response to clear apoptotic cells allowing tissue remodelling later on in the fibrotic heart. Our analysis at the early disease stage suggests cardiac inflammation is an important response and may be one of the mechanisms responsible for AC disease progression.
Assuntos
Arritmias Cardíacas/imunologia , Cardiomiopatias/imunologia , Desmogleína 2/metabolismo , Fibrose/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Inflamação/complicações , Animais , Modelos Animais de Doenças , Humanos , Inflamação/patologia , CamundongosRESUMO
Background The IND.226 study was a phase Ib study to determine the recommended phase II dose of durvalumab + tremelimumab in combination with standard platinum-doublet chemotherapy. Sequential administration of multiple agents increases total chair time adding costs overall and inconvenience for patients. This cohort of the IND.226 study evaluated the safety and tolerability of durvalumab + tremelimumab given either sequentially (SEQ) or concurrently (CON). Methods Patients with advanced solid tumours were enrolled and randomised to either SEQ tremelimumab 75 mg IV over 1 h followed by durvalumab 1500 mg IV over 1 h q4wks on the same day, or CON administration over 1 h. The serum pharmacokinetic profile of SEQ versus CON of durvalumab and tremelimumab administration was also evaluated. Results 14 patients either received SEQ (n = 7pts) or CON (n = 7 pts). There were no infusion related reactions. Drug related adverse events (AEs) were mainly low grade and manageable, and comparable in frequency between SEQ/CON- fatigue (43%/57%), rash (43%/43%), pruritus (43%/29%) and nausea (14%/29%). One patient in each cohort discontinued treatment due to toxicity. The PK profiles of durvalumab and tremelimumab were similar between CON and SEQ, and to historical reference data. Conclusions Concurrent administration of durvalumab and tremelimumab over 1 h is safe with a comparable PK profile to sequential administration.
Assuntos
Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais/administração & dosagem , Antineoplásicos Imunológicos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Inibidores de Checkpoint Imunológico/administração & dosagem , Neoplasias/tratamento farmacológico , Adulto , Idoso , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/sangue , Anticorpos Monoclonais/farmacocinética , Anticorpos Monoclonais Humanizados/efeitos adversos , Anticorpos Monoclonais Humanizados/sangue , Anticorpos Monoclonais Humanizados/farmacocinética , Antineoplásicos Imunológicos/efeitos adversos , Antineoplásicos Imunológicos/sangue , Antineoplásicos Imunológicos/farmacocinética , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Feminino , Humanos , Inibidores de Checkpoint Imunológico/efeitos adversos , Inibidores de Checkpoint Imunológico/sangue , Inibidores de Checkpoint Imunológico/farmacocinética , Masculino , Pessoa de Meia-Idade , Neoplasias/sangue , Neoplasias/metabolismoRESUMO
BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is an inherited, frequently underdiagnosed disorder, which can predispose individuals to sudden cardiac death. Rare, recessive forms of AC can be associated with woolly hair and palmoplantar keratoderma, but most autosomal dominant AC forms have been reported to be cardiac specific. Causative mutations frequently occur in desmosomal genes including desmoplakin (DSP). OBJECTIVES: In this study, we systematically investigated the presence of a skin and hair phenotype in heterozygous DSP mutation carriers with AC. METHODS: Six AC pedigrees with 38 carriers of a dominant loss-of-function (nonsense or frameshift) mutation in DSP were evaluated by detailed clinical examination (cardiac, hair and skin) and molecular phenotyping. RESULTS: All carriers with mutations affecting both major DSP isoforms (DSPI and II) were observed to have curly or wavy hair in the pedigrees examined, except for members of Family 6, where the position of the mutation only affected the cardiac-specific isoform DSPI. A mild palmoplantar keratoderma was also present in many carriers. Sanger sequencing of cDNA from nonlesional carrier skin suggested degradation of the mutant allele. Immunohistochemistry of patient skin demonstrated mislocalization of DSP and other junctional proteins (plakoglobin, connexin 43) in the basal epidermis. However, in Family 6, DSP localization was comparable with control skin. CONCLUSIONS: This study identifies a highly recognizable cutaneous phenotype associated with dominant loss-of-function DSPI/II mutations underlying AC. Increased awareness of this phenotype among healthcare workers could facilitate a timely diagnosis of AC in the absence of overt cardiac features.
Assuntos
Cardiomiopatias/genética , Desmoplaquinas/genética , Doenças do Cabelo/genética , Ceratodermia Palmar e Plantar/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Cardiomiopatias/diagnóstico , Cardiomiopatias/patologia , Cardiomiopatia Dilatada , Análise Mutacional de DNA , Feminino , Doenças do Cabelo/diagnóstico , Doenças do Cabelo/patologia , Coração/diagnóstico por imagem , Heterozigoto , Humanos , Ceratodermia Palmar e Plantar/diagnóstico , Ceratodermia Palmar e Plantar/patologia , Mutação com Perda de Função , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Linhagem , Isoformas de Proteínas/genética , Pele/patologia , Adulto JovemRESUMO
OBJECTIVE: HPV infection has been associated with deregulation of the PI3K-Akt-mTOR pathway in invasive cervical carcinomas. This 2-stage phase II study assessed the activity of the mTOR inhibitor, temsirolimus, in patients with measurable metastatic and/or locally advanced, recurrent carcinoma of the cervix. METHODS: Temsirolimus 25mg i.v. was administered weekly in 4 week cycles. One response among the first 18 patients was required to proceed to the second stage of accrual. Correlative molecular studies were performed on archival tumor tissue. RESULTS: Thirty-eight patients were enrolled. Thirty-seven patients were evaluable for toxicity and 33 for response. One patient experienced a partial response (3.0%). Nineteen patients had stable disease (57.6%) [median duration 6.5 months (range 2.4-12.0mo)]. The 6-month progression free survival rate was 28% (95% CI: 14-43%). The median progression free survival was 3.52 months [95% CI (1.81-4.70)]. Adverse effects were mild-moderate in most cases and similar to other temsirolimus studies. No toxicity>grade 3 was observed. Assessment of PTEN and PIK3CA by IHC, copy number analyses and PTEN promoter methylation status did not reveal subsets associated with disease stability. CONCLUSION: Single agent temsirolimus has modest activity in cervical carcinoma with about two-thirds of patients exhibiting stable disease. Molecular markers for treatment benefit remain to be identified.
Assuntos
Antineoplásicos/uso terapêutico , Recidiva Local de Neoplasia/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Sirolimo/análogos & derivados , Serina-Treonina Quinases TOR/antagonistas & inibidores , Neoplasias do Colo do Útero/tratamento farmacológico , Adulto , Idoso , Classe I de Fosfatidilinositol 3-Quinases , Intervalo Livre de Doença , Feminino , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , PTEN Fosfo-Hidrolase/análise , Fosfatidilinositol 3-Quinases/análise , Sirolimo/efeitos adversos , Sirolimo/uso terapêutico , Neoplasias do Colo do Útero/mortalidadeRESUMO
AIMS/HYPOTHESIS: Dominantly acting loss-of-function mutations in the ABCC8/KCNJ11 genes can cause mild medically responsive hyperinsulinaemic hypoglycaemia (HH). As controversy exists over whether these mutations predispose to diabetes in adulthood we investigated the prevalence of diabetes in families with dominantly inherited ATP-sensitive potassium (K(ATP)) channel mutations causing HH in the proband. METHODS: We studied the phenotype of 30 mutation carriers (14 children and 16 adults) from nine families with dominant ABCC8/KCNJ11 mutations. Functional consequences of six novel missense mutations were examined by reconstituting the K(ATP) channel in human embryonic kidney 293 (HEK293) cells and evaluating the effect of drugs and metabolic poisoning on the channels using the (86)Rb flux assay. RESULTS: The mutant channels all showed a lack of (86)Rb efflux on exposure to the channel agonist diazoxide or metabolic inhibition. In the families, dominant ABCC8/KCNJ11 mutations were associated with increased birthweight (median + 1.56 SD score [SDS]). Fourteen children had HH and five adults were reported with HH or hypoglycaemic episodes (63%). Progression from hypoglycaemia to diabetes mellitus occurred in two individuals. Eight adults had a history of gestational diabetes in multiple pregnancies or were diabetic (diagnosed at a median age of 31 years). Within these families, none of the 19 adults who were not carriers of the ABCC8/KCNJ11 mutation was known to be diabetic. CONCLUSIONS/INTERPRETATION: The phenotype associated with dominant ABCC8/KCNJ11 mutations ranges from asymptomatic macrosomia to persistent HH in childhood. In adults, it may also be an important cause of dominantly inherited early-onset diabetes mellitus.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Diabetes Mellitus/etiologia , Diabetes Mellitus/genética , Hiperinsulinismo/etiologia , Hiperinsulinismo/genética , Hipoglicemia/etiologia , Hipoglicemia/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Receptores de Droga/genética , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Receptores de Sulfonilureias , Adulto JovemRESUMO
OBJECTIVE: Clear cell carcinoma (CCC) of the ovary is increasingly recognized as responding poorly to chemotherapy (CT). This review examines the outcomes achieved with a variety of CT regimens, looking for evidence of activity that might guide the development of more effective treatments. METHODS: A retrospective chart review of all cases of CCC referred to the BC Cancer Agency (BCCA) between 2000 and 2008 was conducted. Data were collected from those with primarily advanced disease and from those who recurred after adjuvant treatment. Outcomes were measured using broad definitions of treatment benefit (any objective or subjective evidence of disease control) in order to reflect the real-life use of palliative therapy. RESULTS: There were 158 women with pure CCC. First-line therapy for advanced disease was delivered to 33 patients. Second- and third-line treatment was delivered to 47 and 25 patients, respectively. The total number of treatment courses was 105: 88 CT-alone courses, 14 radiation therapy (RT)-alone and 3 combined modality. Treatment benefit was recorded in 24% of patients receiving CT, 64% of patients receiving RT, and each who received combined modality treatment. There was no CT drug class identified as obviously efficacious. CONCLUSION: Most patients with advanced or recurrent CCC have a low benefit-to-failure ratio from palliative CT. The role of RT and targeted agents must be explored to improve clinical outcomes for such patients.
Assuntos
Adenocarcinoma de Células Claras/tratamento farmacológico , Recidiva Local de Neoplasia/tratamento farmacológico , Neoplasias Ovarianas/tratamento farmacológico , Cuidados Paliativos/métodos , Antraciclinas/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carboplatina/administração & dosagem , Cisplatino/administração & dosagem , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Etoposídeo/administração & dosagem , Feminino , Humanos , Paclitaxel/administração & dosagem , Topotecan/administração & dosagem , Resultado do Tratamento , GencitabinaRESUMO
â¢Gliomatosis peritonei (GP) is a rare benign complication of ovarian teratomas that does not impact overall survival.â¢GP exhibits high 18-F FDG uptake unlike other non-malignant forms of mature teratoma.â¢The specific characteristics of GP on functional imaging may be used to follow it with active surveillance in select cases.
RESUMO
A woman's right to health includes her right to a healthy childbirth and newborn, and the baby possesses his or her own right to life as well. While overall child mortality has declined, 4 million newborns still die each year, primarily in the first days of life. Most could be prevented through existing, cost-effective interventions. Field trials and programs show that low-cost, home- or community-based neonatal care can quickly lead to dramatic decline in neonatal mortality. Newborn health should be integrated with maternal and child health-and these programs should be strengthened and expanded-in order to achieve both the child and maternal survival Millennium Development Goals. Policies and programs should include participatory household and community-based care, with links to the formal health system. Despite recent attention to newborn health, much remains to be done to achieve sustained, high coverage of effective interventions, especially in poor communities where most newborns are born and die, mostly in the first week of life.
Assuntos
Serviços de Saúde da Criança , Mortalidade Infantil , Serviços de Saúde Materna , Assistência Perinatal , Valor da Vida , Criança , Proteção da Criança , Países em Desenvolvimento , Feminino , Direitos Humanos , Humanos , Cuidado do Lactente , Recém-Nascido , Gravidez , Cuidado Pré-NatalRESUMO
Hematogenous metastases are rarely present at diagnosis of ovarian clear cell carcinoma (OCC). Instead dissemination of these tumors is characteristically via direct extension of the primary tumor into nearby organs and the spread of exfoliated tumor cells throughout the peritoneum, initially via the peritoneal fluid, and later via ascites that accumulates as a result of disruption of the lymphatic system. The molecular mechanisms orchestrating these processes are uncertain. In particular, the signaling pathways used by malignant cells to survive the stresses of anchorage-free growth in peritoneal fluid and ascites, and to colonize remote sites, are poorly defined. We demonstrate that the transmembrane glycoprotein CUB-domain-containing protein 1 (CDCP1) has important and inhibitable roles in these processes. In vitro assays indicate that CDCP1 mediates formation and survival of OCC spheroids, as well as cell migration and chemoresistance. Disruption of CDCP1 via silencing and antibody-mediated inhibition markedly reduce the ability of TOV21G OCC cells to form intraperitoneal tumors and induce accumulation of ascites in mice. Mechanistically our data suggest that CDCP1 effects are mediated via a novel mechanism of protein kinase B (Akt) activation. Immunohistochemical analysis also suggested that CDCP1 is functionally important in OCC, with its expression elevated in 90% of 198 OCC tumors and increased CDCP1 expression correlating with poor patient disease-free and overall survival. This analysis also showed that CDCP1 is largely restricted to the surface of malignant cells where it is accessible to therapeutic antibodies. Importantly, antibody-mediated blockade of CDCP1 in vivo significantly increased the anti-tumor efficacy of carboplatin, the chemotherapy most commonly used to treat OCC. In summary, our data indicate that CDCP1 is important in the progression of OCC and that targeting pathways mediated by this protein may be useful for the management of OCC, potentially in combination with chemotherapies and agents targeting the Akt pathway.
Assuntos
Adenocarcinoma de Células Claras/mortalidade , Adenocarcinoma de Células Claras/patologia , Antígenos CD/metabolismo , Moléculas de Adesão Celular/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Ovarianas/mortalidade , Neoplasias Ovarianas/patologia , Adenocarcinoma de Células Claras/metabolismo , Animais , Antígenos CD/análise , Antígenos CD/genética , Antígenos de Neoplasias , Carboplatina/farmacologia , Moléculas de Adesão Celular/análise , Moléculas de Adesão Celular/genética , Linhagem Celular Tumoral/efeitos dos fármacos , Movimento Celular , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Estimativa de Kaplan-Meier , Camundongos Endogâmicos NOD , Proteínas de Neoplasias/análise , Proteínas de Neoplasias/genética , Neoplasias Ovarianas/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Esferoides Celulares/metabolismo , Esferoides Celulares/patologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: Urocortin is a novel cardioprotective agent that can protect cardiac myocytes from the damaging effects of ischemia/reperfusion both in culture and in the intact heart and is effective when given at reperfusion. METHODS AND RESULTS: We have analyzed global changes in gene expression in cardiac myocytes after urocortin treatment using gene chip technology. We report that urocortin specifically induces enhanced expression of the Kir 6.1 cardiac potassium channel subunit. On the basis of this finding, we showed that the cardioprotective effect of urocortin both in isolated cardiac cells and in the intact heart is specifically blocked by both generalized and mitochondrial-specific K(ATP) channel blockers, whereas the cardioprotective effect of cardiotrophin-1 is unaffected. Conversely, inhibiting the Kir 6.1 channel subunit greatly enhances cardiac cell death after ischemia. CONCLUSIONS: This is, to our knowledge, the first report of the altered expression of a K(ATP) channel subunit induced by a cardioprotective agent and demonstrates that K(ATP) channel opening is essential for the effect of this novel cardioprotective agent.
Assuntos
Cardiotônicos/farmacologia , Hormônio Liberador da Corticotropina/farmacologia , Miocárdio/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/biossíntese , Canais de Potássio Corretores do Fluxo de Internalização/fisiologia , Trifosfato de Adenosina/metabolismo , Animais , Morte Celular , Hipóxia Celular , Células Cultivadas , Citocinas/farmacologia , Perfilação da Expressão Gênica , Traumatismo por Reperfusão Miocárdica/metabolismo , Miocárdio/citologia , Análise de Sequência com Séries de Oligonucleotídeos , Canais de Potássio Corretores do Fluxo de Internalização/genética , RNA Mensageiro/biossíntese , Ratos , Ratos Sprague-Dawley , Ativação Transcricional , UrocortinasRESUMO
The sarcoplasmic reticulum Ca(2+)-release channel plays a central role in cardiac muscle function by providing a ligand-regulated pathway for the release of sequestered Ca2+ to initiate contraction following cell excitation. The efficiency of the channel as a Ca(2+)-release pathway will be influenced by both gating and conductance properties of the system. In the past we have investigated conduction and discrimination of inorganic mono- and divalent cations with the aim of describing the mechanisms governing ion handling in the channel (Tinker, A., A.R. G. Lindsay, and A.J. Williams. 1992. Journal of General Physiology. 100:495-517.). In the present study, we have used permeant and impermeant organic cations to provide additional information on structural features of the conduction pathway. The use of permeant organic cations in biological channels to explore structural motifs underlying selectivity has been an important tool for the electrophysiologist. We have examined the conduction properties of a series of monovalent organic cations of varying size in the purified sheep cardiac sarcoplasmic reticulum Ca(2+)-release channel. Relative permeability, determined from the reversal potential measured under bi-ionic conditions with 210-mM test cation at the cytoplasmic face of the channel and 210 mM K+ at the luminal, was related inversely to the minimum circular cation radius. The reversal potential was concentration-independent. The excluded area hypothesis, with and without a term for solute-wall friction, described the data well and gave a lower estimate for minimum pore radius of 3.3-3.5 A. Blocking studies with the impermeant charged derivative of triethylamine reveal that this narrowing occurs over the first 10-20% of the voltage drop when crossing from the lumen of the SR to the cytoplasm. Single-channel conductances were measured in symmetrical 210 mM salt. Factors other than relative permeability determine conductance as ions with similar relative permeability can have widely varying single-channel conductance. Permeant ions, such as the charged derivatives of trimethylamine and diethylmethylamine, can also inhibit K+ current. The reduction in relative conductance with increasing concentrations of these two ions at a holding potential of 60 mV was described by a rectangular hyperbola and revealed higher affinity binding for diethylmethylamine as compared to trimethylamine. It was possible to describe the complex permeation properties of these two ions using a single-ion four barrier, three binding site Eyring rate theory model. In conclusion, these studies reveal that the cardiac Ca(2+)-release channel has a selectivity filter of approximately 3.5-A radius located at the luminal face of the protein.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Canais de Cálcio/metabolismo , Cátions/farmacologia , Miocárdio/metabolismo , Retículo Sarcoplasmático/metabolismo , Animais , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/ultraestrutura , Técnicas In Vitro , Ativação do Canal Iônico/efeitos dos fármacos , Bicamadas Lipídicas , Potenciais da Membrana/efeitos dos fármacos , Modelos Biológicos , Permeabilidade , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/ultraestrutura , OvinosRESUMO
The conduction properties of the alkaline earth divalent cations were determined in the purified sheep cardiac sarcoplasmic reticulum ryanodine receptor channel after reconstitution into planar phospholipid bilayers. Under bi-ionic conditions there was little difference in permeability among Ba2+, Ca2+, Sr2+, and Mg2+. However, there was a significant difference between the divalent cations and K+, with the divalent cations between 5.8- and 6.7-fold more permeant. Single-channel conductances were determined under symmetrical ionic conditions with 210 mM Ba2+ and Sr2+ and from the single-channel current-voltage relationship under bi-ionic conditions with 210 mM divalent cations and 210 mM K+. Single-channel conductance ranged from 202 pS for Ba2+ to 89 pS for Mg2+ and fell in the sequence Ba2+ greater than Sr2+ greater than Ca2+ greater than Mg2+. Near-maximal single-channel conductance is observed at concentrations as low as 2 mM Ba2+. Single-channel conductance and current measurements in mixtures of Ba(2+)-Mg2+ and Ba(2+)-Ca2+ reveal no anomalous behavior as the mole fraction of the ions is varied. The Ca(2+)-K+ reversal potential determined under bi-ionic conditions was independent of the absolute value of the ion concentrations. The data are compatible with the ryanodine receptor channel acting as a high conductance channel displaying moderate discrimination between divalent and monovalent cations. The channel behaves as though ion translocation occurs in single file with at most one ion able to occupy the conduction pathway at a time.
Assuntos
Cátions Bivalentes/farmacocinética , Canais Iônicos/fisiologia , Miocárdio/ultraestrutura , Receptores Colinérgicos/fisiologia , Retículo Sarcoplasmático/ultraestrutura , Animais , Bário/farmacocinética , Transporte Biológico/fisiologia , Cálcio/farmacocinética , Permeabilidade da Membrana Celular/fisiologia , Condutividade Elétrica/fisiologia , Coração/fisiologia , Membranas Intracelulares/química , Membranas Intracelulares/fisiologia , Membranas Intracelulares/ultraestrutura , Bicamadas Lipídicas , Magnésio/farmacocinética , Potenciais da Membrana/fisiologia , Miocárdio/química , Receptores Colinérgicos/análise , Canal de Liberação de Cálcio do Receptor de Rianodina , Retículo Sarcoplasmático/química , Retículo Sarcoplasmático/fisiologia , Estrôncio/farmacocinéticaRESUMO
Under appropriate conditions, the interaction of the plant alkaloid ryanodine with a single cardiac sarcoplasmic reticulum Ca(2+)-release channel results in a profound modification of both channel gating and conduction. On modification, the channel undergoes a dramatic increase in open probability and a change in single-channel conductance. In this paper we aim to provide a mechanistic framework for the interpretation of the altered conductance seen after ryanodine binding to the channel protein. To do this we have characterized single-channel conductance with representative members of three classes of permeant cation; group 1a monovalent cations, alkaline earth divalent cations, and organic monovalent cations. We have quantified the change in single-channel conductance induced by ryanodine and have expressed this as a fraction of conductance in the absence of ryanodine. Fractional conductance seen in symmetrical 210 mM solutions is not fixed but varies with the nature of the permeant cation. The group 1a monovalent cations (K+, Na+, Cs+, Li+) have values of fractional conductance in a narrow range (0.60-0.66). With divalent cations fractional conductance is considerably lower (Ba2+, 0.22 and Sr2+, 0.28), whereas values of fractional conductance vary considerably with the organic monovalent cations (ammonia 0.66, ethylamine 0.76, propanolamine 0.65, diethanolamine 0.92, diethylamine 1.2). To establish the mechanisms governing these differences, we have monitored the affinity of the conduction pathway for, and the relative permeability of, representative cations in the ryanodine-modified channel. These parameters have been compared with those obtained in previous studies from this laboratory using the channel in the absence of ryanodine and have been modeled by modifying our existing single-ion, four-barrier three-well rate theory model of conduction in the unmodified channel. Our findings indicate that the high affinity, essentially irreversible, interaction of ryanodine with the cardiac sarcoplasmic reticulum Ca(2+)-release channel produces a conformational alteration of the protein which results in modified ion handling. We suggest that, on modification, the affinity of the channel for the group 1a monovalent cations is increased while the relative permeability of this class of cations remains essentially unaltered. The affinity of the conduction pathway for the alkaline earth divalent cations is also increased, however the relative permeability of this class of cations is reduced compared to the unmodified channel. The influence of modification on the handling by the channel of the organic monovalent cations is determined by both the size and the nature of the cation.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Canais de Cálcio/metabolismo , Cátions/metabolismo , Miocárdio/metabolismo , Rianodina/metabolismo , Retículo Sarcoplasmático/metabolismo , Animais , Canais de Cálcio/efeitos dos fármacos , Permeabilidade da Membrana Celular , Ativação do Canal Iônico , Transporte de Íons/efeitos dos fármacos , Potenciais da Membrana , Miocárdio/citologia , Rianodina/farmacologia , Retículo Sarcoplasmático/efeitos dos fármacos , OvinosRESUMO
A model is developed for ionic conduction in the sheep cardiac sarcoplasmic reticulum ryanodine receptor channel based on Eyring rate theory. A simple scheme is proposed founded on single-ion occupancy and an energy profile with four barriers and three binding sites. The model is able to quantitatively predict a large number of conduction properties of the purified and native receptor with monovalent and divalent cations as permeant species. It suggests that discrimination between divalent and monovalent cations is due to a high affinity central binding site and a process that favors the passage of divalent cations between binding sites. Furthermore, differences in conductance among the group Ia cations and among the alkaline earths are largely explained by differing affinity at this putative central binding site.
Assuntos
Canais Iônicos/fisiologia , Miocárdio/ultraestrutura , Receptores Colinérgicos/fisiologia , Retículo Sarcoplasmático/ultraestrutura , Animais , Cálcio/farmacocinética , Permeabilidade da Membrana Celular/fisiologia , Coração/fisiologia , Membranas Intracelulares/química , Membranas Intracelulares/fisiologia , Membranas Intracelulares/ultraestrutura , Magnésio/farmacocinética , Modelos Biológicos , Miocárdio/química , Receptores Colinérgicos/análise , Canal de Liberação de Cálcio do Receptor de Rianodina , Retículo Sarcoplasmático/química , Retículo Sarcoplasmático/fisiologia , Ovinos , TrometaminaRESUMO
OBJECTIVE: The aim was to perform a theoretical and experimental study of the possible variations in Ca2+ current through the open cardiac sarcoplasmic reticular Ca2+ release channel under the ionic conditions associated with physiological and pathophysiological states. METHODS: The sheep cardiac sarcoplasmic reticular Ca2+ release channel was purified and reconstituted into planar phospholipid bilayers for study under voltage clamp conditions. Single channel current-voltage relationships were measured under putative physiological conditions with 1, 5, and 10 mM intraluminal Ca2+. The mathematics of a computer model based on Eyring rate theory were extended to include the interactions of three permeant ions. RESULTS: A model used previously to describe ionic conduction under simpler ionic conditions was able to predict the interaction of Ca2+, Mg2+, and K+ in the probable physiological range over the voltage range of interest. The predicted Ca2+ current under ionic conditions proposed to occur at the end of diastole is sensitive to relatively small changes in holding potential which suggests the need for adequate charge compensation across the sarcoplasmic reticular membrane. Theoretically, it was predicted that variations in intraluminal Ca2+, such as may occur in Ca2+ overload and other conditions, and variations in cytosolic Mg2+, which may occur in myocardial stunning, may significantly affect Ca2+ flux through the open Ca2+ release channel. CONCLUSIONS: Variations in permeant ion concentration such as may occur in physiological and pathophysiological states may significantly affect the quantity of Ca2+ released from the cardiac sarcoplasmic reticulum.
Assuntos
Canais de Cálcio/metabolismo , Bombas de Íon/metabolismo , Modelos Cardiovasculares , Retículo Sarcoplasmático/metabolismo , Animais , Cálcio/metabolismo , Membrana Celular/metabolismo , Citosol/metabolismo , Magnésio/metabolismo , Miocárdio Atordoado/metabolismo , Potássio/metabolismo , OvinosRESUMO
OBJECTIVE: Jervell and Lange-Nielsen syndrome (JLNS) is a recessively inherited long QT syndrome (LQTS) characterised by profound sensorineural deafness and predisposition to syncope and sudden cardiac death. Mutation analysis has established the presence of mutations in affected individuals in the genes KCNQ1 and KCNE1: the potassium channel complex responsible for the cardiac I(Ks) current involved in repolarisation of the ventricular action potential. Our objective was to determine the functional effects of disease causing mutations in JLNS. METHODS: In this study we have investigated the electrophysiological effects of eight distinct JLNS mutations after expression of cRNA in Xenopus laevis oocytes. RESULTS: KCNE1 mutant T59P/L60P showed no dominant negative effect and was a pure loss of function mutation. KCNQ1 mutant E261D showed a strong dominant-negative effect. KCNQ1 mutant R243H produced a moderate dominant-negative effect, right shifted the steady-state activation curve and led to an increased deactivation rate. The behaviour of KCNQ1 mutants 572-576del, 1008delC, R518X, Q530X, R594Q depended on the relative quantities of mutant and wild-type proteins (with a weak dominant-negative effect present at 1:3 but not 1:1 injection ratios). These data indicate the presence of an additional assembly domain before S2-S3 and the importance of the S4-S5 region in channel function and gating. CONCLUSIONS: Our data suggest a spectrum of behaviour for disease causing mutations from simple loss of function through to prominent dominant negative behaviour.
Assuntos
Ativação do Canal Iônico , Síndrome do QT Longo/genética , Síndrome do QT Longo/fisiopatologia , Canais de Potássio/genética , Animais , Feminino , Expressão Gênica , Heterozigoto , Humanos , Mutagênese Sítio-Dirigida , Mutação , Oócitos/metabolismo , Isoformas de Proteínas/genética , Xenopus laevisRESUMO
Carboplatin and paclitaxel, delivered on a 3-weekly basis, is the historical standard for the management of advanced epithelial ovarian cancers (EOC). Increased dose intensity, the inclusion of additional active cytotoxic agents and lengthening treatment duration have failed to improve the outcomes seen with standard doses of carboplatin and paclitaxel in the treatment of EOC. Dose-dense (i.e. weekly) delivery of paclitaxel may exploit anticancer mechanisms such as anti-angiogenesis and the induction of apoptosis. Tumour regrowth may be more effectively impaired by the dose-dense delivery of paclitaxel. Non-randomised studies of dose-dense chemotherapy in EOC have been promising, particularly in heavily pretreated and platinum-resistant disease, with reported response rates as high as 60%. Dose-dense paclitaxel also seems to be well tolerated. These observations led to a number of comparative trials of dose-dense paclitaxel chemotherapy, three have been reported and four are ongoing. This review explores the rationale behind dose-dense delivery of paclitaxel and evaluates the results of completed phase III trials.
Assuntos
Antineoplásicos Fitogênicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ovarianas/tratamento farmacológico , Paclitaxel/uso terapêutico , Antineoplásicos Fitogênicos/administração & dosagem , Ensaios Clínicos como Assunto , Esquema de Medicação , Feminino , Humanos , Paclitaxel/administração & dosagemRESUMO
In vivo levels of interleukin-1 (IL-1) and IL-6, present in the interstitial spaces of brain, have been repeatedly monitored up to 7 days after insertion of a microdialysis probe, designed to induce mechanical trauma to the brain. IL-1 is barely detectable immediately after implantation but over a 24-48 h period a 15-fold increase is seen. In contrast IL-6 levels at day 0 are high, increasing slightly (10%) by day 1 but decreasing to 40% by day 2. The temporal pattern of IL-6 recovery in the cerebrospinal fluid was similar to that in the dialysate but the levels were significantly lower and may reflect diffusion from the site of the probe lesion. Cellular sources of these cytokines include macrophages and neutrophils, which have infiltrated the lesion and microglia resident in the brain, which can be identified at the lesion site within 24 h of probe implantation. The astrocytic response to injury, evidenced by increased glial fibrillary acidic protein staining occurs much later, by day 7, and is unlikely to be responsible for IL-1 and IL-6 production found at 24-48 h. Since upon isolation and stimulation of microglia in vitro with lipopolysaccharide IL-1 and IL-6 can be measured in the supernatant, it would appear that they have the capacity to produce cytokines in vivo. Localised synthesis of cytokines at sites of brain injury by microglia would further stimulate microglia in an autocrine manner and also propagate the astrocytic reaction.
Assuntos
Lesões Encefálicas/metabolismo , Encéfalo/metabolismo , Citocinas/biossíntese , Interleucina-1/metabolismo , Interleucina-6/metabolismo , Neuroglia/fisiologia , Animais , Diálise/métodos , Imuno-Histoquímica , Ratos , Ratos EndogâmicosRESUMO
Although women live longer than men, new evidence indicates women bear a disproportionately heavy burden of disease. The effect of disease on economic productivity of women in developing countries has been largely ignored. Infections are often causes of disease in women, including those that affect reproductive health. Although men and women usually experience similar rates of many diseases, rates of exposure and treatment vary between men and women. If untreated, factors adversely affecting women's health in one stage compound women's ill health in succeeding stages.
PIP: This article discusses women's health in developing countries, urges improvements, identifies specific causes of death by age, and indicates future trends and effective strategies for improvements. A number of international conferences have been held to discuss women's health issues. Reference is made to the World Bank's "World Development Report for 1993" and the statistic that women suffer more disability than men. Women are considered to have a greater disease burden than men. Effective strategies include preventing or delaying births to women who do not desire any more children. Increased use of family planning and safe abortion might avert 100,000 maternal deaths each year due to pregnancy related causes and 200,000 maternal deaths due to unsafe abortion. Health services might be extended through use of non-health professionals who are trained as health providers. Well-trained traditional birth attendants and an effective referral system were found to be effective in northeast Brazil. The "safe motherhood" interventions of the World Bank are considered to be the most cost effective. Women need to take more responsibility for their own health. Women's disease burden can be reduced by safe motherhood strategies, safe birthing practices, pre- and postnatal care, ready access to quality family planning, safe abortion services, and treatment of sexually transmitted diseases. Women's health might improve with better access to safe water, good hygiene, and knowledge about safe cooking practices and about the maintenance of good health. Strategies must be directed to gender-specific causes of mortality by age group. Migration is expected to affect women's health status. Urban settings and destitute living conditions that force women into prostitution place women at greater risk of morbidity and mortality.