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1.
Ann Oncol ; 29(5): 1292-1303, 2018 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-29509840

RESUMEN

Background: MSR1 repeats are a 36-38 bp minisatellite element that have recently been implicated in the regulation of gene expression, through copy number variation (CNV). Patients and methods: Bioinformatic and experimental methods were used to assess the distribution of MSR1 across the genome, evaluate the regulatory potential of such elements and explore the role of MSR1 elements in cancer, particularly non-familial breast cancer and prostate cancer. Results: MSR1s are predominately located at chromosome 19 and are functionally enriched in regulatory regions of the genome, particularly regions implicated in short-range regulatory activities (H3K27ac, H3K4me1 and H3K4me3). MSR1-regulated genes were found to have specific molecular roles, such as serine-protease activity (P = 4.80 × 10-7) and ion channel activity (P = 2.7 × 10-4). The kallikrein locus was found to contain a large number of MSR1 clusters, and at least six of these showed CNV. An MSR1 cluster was identified within KLK14, with 9 and 11 copies being normal variants. A significant association with the 9-copy allele and non-familial breast cancer was found in two independent populations (P = 0.004; P = 0.03). In the white British population, the minor allele conferred an increased risk of 1.21-3.51 times for all non-familial disease, or 1.7-5.3 times in early-onset disease. The 9-copy allele was also found to be associated with increased risk of prostate cancer in an independent population (odds ratio = 1.27-1.56; P =0.009). Conclusions: MSR1 repeats act as molecular switches that modulate gene expression. It is likely that CNV of MSR1 will affect risk of development of various forms of cancer, including that of breast and prostate. The MSR1 cluster at KLK14 represents the strongest risk factor identified to date in non-familial breast cancer and a significant risk factor for prostate cancer. Analysis of MSR1 genotype will allow development of precise stratification of disease risk and provide a novel target for therapeutic agents.


Asunto(s)
Neoplasias de la Mama/genética , Regulación Neoplásica de la Expresión Génica/genética , Predisposición Genética a la Enfermedad , Repeticiones de Minisatélite/genética , Neoplasias de la Próstata/genética , Edad de Inicio , Neoplasias de la Mama/patología , Estudios de Casos y Controles , Biología Computacional , Variaciones en el Número de Copia de ADN , Femenino , Mutación de Línea Germinal , Histonas/genética , Humanos , Calicreínas/genética , Masculino , Persona de Mediana Edad , Familia de Multigenes/genética , Neoplasias de la Próstata/patología , Medición de Riesgo/métodos
2.
J Behav Ther Exp Psychiatry ; 54: 239-246, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27620071

RESUMEN

BACKGROUND AND OBJECTIVES: It is well established that attention bias and interpretation bias each have a key role in the development and continuation of anxiety. How the biases may interact with one another in anxiety is, however, poorly understood. Using cognitive bias modification techniques, the present study examined whether training a more positive interpretation bias or attention bias resulted in transfer of effects to the untrained cognitive domain. Differences in anxiety reactivity to a real-world stressor were also assessed. METHODS: Ninety-seven first year undergraduates who had self-reported anxiety were allocated to one of four groups: attention bias training (n = 24), interpretation bias training (n = 26), control task training (n = 25) and no training (n = 22). Training was computer-based and comprised eight sessions over four weeks. Baseline and follow-up measures of attention and interpretation bias, anxiety and depression were taken. RESULTS: A significant reduction in threat-related attention bias and an increase in positive interpretation bias occurred in the attention bias training group. The interpretation bias training group did not exhibit a significant change in attention bias, only interpretation bias. The effect of attention bias training on interpretation bias was significant as compared with the two control groups. There were no effects on self-report measures. LIMITATIONS: The extent to which interpretive training can modify attentional processing remains unclear. CONCLUSIONS: Findings support the idea that attentional training might have broad cognitive consequences, impacting downstream on interpretive bias. However, they do not fully support a common mechanism hypothesis, as interpretive training did not impact on attentional bias.


Asunto(s)
Atención/fisiología , Sesgo , Trastornos del Conocimiento/rehabilitación , Terapia Cognitivo-Conductual/métodos , Emociones/fisiología , Transferencia de Experiencia en Psicología , Adolescente , Análisis de Varianza , Ansiedad/complicaciones , Ansiedad/rehabilitación , Trastornos del Conocimiento/etiología , Depresión/complicaciones , Depresión/rehabilitación , Retroalimentación Psicológica , Femenino , Estudios de Seguimiento , Humanos , Masculino , Escalas de Valoración Psiquiátrica , Tiempo de Reacción/fisiología , Autoinforme , Encuestas y Cuestionarios , Adulto Joven
3.
Cytokine ; 12(4): 388-96, 2000 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-10805221

RESUMEN

This is the first report of the serum profile of a glycosylated recombinant form of human IL-6 (rhIL-6) administered subcutaneously (1-10 microg/kg/day) in a phase I/II trial as a thrombopoietic agent in patients with advanced cancer. The pharmacodynamic effects of IL-6 were also examined. Detailed pharmacokinetic measurements were made in four patients. Peak concentrations at 5-8 h and a median t0.5 of ca. 5 h were similar to those previously reported for non-glycosylated IL-6. However, higher peak concentrations and apparent differences in effective dose levels to those previously reported with the non-glycosylated form were seen. Indications of an apparent attenuation in circulating IL-6 concentrations with continuing injections were seen in eight of 10 patients examined but anti-IL-6 antibody generation was seen in only two patients. Soluble interleukin 6 receptor concentrations generally decreased. No major changes in T cell subsets were seen but expression of CD25 and CD54 by T lymphocytes significantly increased, accompanied by marked increases in soluble CD25 (sIL-2R) and CD54 (sICAM-1). No consistent change in B cells, monocytes or NK cells were seen. No evidence for induction of TNF-alpha was found. This study demonstrates similar biological effects of glycosylated rhIL-6 to those reported for the non-glycosylated form but illustrates several apparent differences which are discussed further.


Asunto(s)
Adyuvantes Inmunológicos/farmacocinética , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias del Colon/tratamiento farmacológico , Interleucina-6/farmacocinética , Melanoma/tratamiento farmacológico , Adyuvantes Inmunológicos/administración & dosificación , Adyuvantes Inmunológicos/uso terapéutico , Adulto , Antígenos CD/clasificación , Biomarcadores , Neoplasias de la Mama/sangre , Neoplasias de la Mama/inmunología , Neoplasias del Colon/sangre , Neoplasias del Colon/inmunología , Femenino , Glicosilación , Humanos , Inmunofenotipificación , Inyecciones Subcutáneas , Interleucina-6/administración & dosificación , Interleucina-6/inmunología , Interleucina-6/uso terapéutico , Leucocitos Mononucleares/clasificación , Leucocitos Mononucleares/inmunología , Masculino , Melanoma/sangre , Melanoma/inmunología , Persona de Mediana Edad , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/farmacocinética , Proteínas Recombinantes/uso terapéutico , Factor de Necrosis Tumoral alfa/análisis
4.
Int J STD AIDS ; 8(10): 622-8, 1997 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-9310221

RESUMEN

The number of clinic consultations for condylomata acuminata (genital warts) has increased substantially during the last 30 years. Most infections produce benign lesions but a few types may be associated with cervical and penile cancers. Interferons (IFN) have shown antiviral properties to these infections and IFN-beta in particular has demonstrated a specific cytopathic effect in humans. A total of 124 patients with condylomata acuminata, the majority of whom had failed previous therapy, were treated intralesionally with either recombinant human interferon-beta la (r-hIFN-beta-1a) or placebo. Up to 6 lesions were treated in each patient, and injections were made 3 times per week for a total of 9 injections. The patients were then followed up for 3 months. Efficacy assessments at all time points (day 19, week 6 and month 3) showed a clear advantage for the r-hIFN-beta-1a interferon-beta treatment. Patients receiving r-hIFN-beta-1a showed a greater proportion of treatment success in terms of the complete or partial reduction (at least 50%) of the total area of the treated lesions. The treatment was also well tolerated. Headache, flu-like symptoms and asthenia were more common in patients receiving r-hIFN-beta-1a, but these adverse events were generally mild in severity and rarely led to patient withdrawal. It was concluded that r-hIFN-beta-1a has good efficacy in condylomata acuminata, and therefore presents a useful therapeutic alternative in this hard-to-treat condition.


Asunto(s)
Condiloma Acuminado/terapia , Interferón beta/uso terapéutico , Adulto , Método Doble Ciego , Femenino , Estudios de Seguimiento , Humanos , Inyecciones Intralesiones , Interferón beta-1a , Masculino , Proteínas Recombinantes/uso terapéutico , Resultado del Tratamiento
5.
Br J Cancer ; 75(3): 423-6, 1997.
Artículo en Inglés | MEDLINE | ID: mdl-9020490

RESUMEN

The combination of 5-fluorouracil (5-FU) and interferon-alpha (IFN-alpha) has reported activity in the treatment of advanced colorectal carcinoma. Laboratory studies of IFN-beta suggest that this agent may offer theoretical advantages over IFN-alpha in combination with 5-FU. A total of 27 patients with advanced or recurrent colorectal carcinoma were treated in a non-randomized open phase II study with a combination of 5-fluorouracil (750 mg m(-1) daily for 5 days as a continuous intravenous (i.v.) infusion followed, from day 15, by i.v. bolus 750 mg m(-2) every 7 days) and recombinant interferon-beta [r-hIFN-beta-1a; 9 MIU (total dose) by subcutaneous injection from day 1 on every Monday, Wednesday and Friday throughout the treatment period]. Toxicity was less than that seen with this schedule of 5-FU in combination with IFN-alpha. Among 21 evaluable patients, four objective responses were seen. Recombinant human interferon-beta-1a in combination with 5-FU is an acceptable regimen in terms of toxicity. However, the study did not demonstrate a superior response rate when compared with previous reports of treatment with 5-FU alone or in combination with IFN-alpha.


Asunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Antineoplásicos/uso terapéutico , Neoplasias del Colon/terapia , Fluorouracilo/uso terapéutico , Interferón beta/uso terapéutico , Neoplasias del Recto/terapia , Adulto , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos/efectos adversos , Antineoplásicos/efectos adversos , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/mortalidad , Femenino , Fluorouracilo/efectos adversos , Humanos , Interferón beta/efectos adversos , Interferones , Masculino , Persona de Mediana Edad , Neutropenia/inducido químicamente , Selección de Paciente , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Neoplasias del Recto/tratamiento farmacológico , Neoplasias del Recto/mortalidad , Tasa de Supervivencia
7.
Cytokine ; 8(9): 717-23, 1996 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-8932983

RESUMEN

Platelet numbers and circulating haemopoietic progenitor cells were examined in 12 patients with advanced malignancies who were receiving recombinant human interleukin-6 (rhIL-6) as part of an investigation of its thrombopoietic effects. Patients received recombinant glycosylated IL-6 by daily subcutaneous injection for 7 consecutive days in doses of 1, 3 or 10 micrograms/kg/day. Platelet numbers increased reaching a peak on days 12-15 with a mean on day 15 of 198.1% of pre-treatment values. This was accompanied by a significant fall in the mean platelet volume (mean decrease of 10.6%, P = 0.0044). No significant correlation was seen between the IL-6 dose and the change in platelet number. No significant differences were observed between pre- and post-treatment levels of circulating erythroid burst-forming units (E-BFU) and granulocyte macrophage colony-forming units (GM-CFU) but a small significant increase was seen in circulating primitive progenitor cells measured in a plastic-adherent (P delta) assay (P = 0.025). As positive controls, a group of patients treated with cyclophosphamide/G-CSF showed significant increases in GM-CFU (P = 0.018), E-BFU (P = 0.018) and P delta progenitors (P = 0.028). These data suggest that the thrombopoietic effects of IL-6 are mediated at a relatively late stage via effects on megakaryocyte differentiation, with a relatively small effect on circulating haemopoietic progenitors.


Asunto(s)
Plaquetas/efectos de los fármacos , Células Madre Hematopoyéticas/efectos de los fármacos , Interleucina-6/uso terapéutico , Neoplasias/sangre , Adulto , Antineoplásicos/uso terapéutico , Plaquetas/patología , Diferenciación Celular/efectos de los fármacos , Ensayo de Unidades Formadoras de Colonias , Ciclofosfamida/uso terapéutico , Células Madre Hematopoyéticas/patología , Humanos , Inyecciones Subcutáneas , Persona de Mediana Edad , Neoplasias/terapia , Recuento de Plaquetas/efectos de los fármacos , Proteínas Recombinantes/uso terapéutico
9.
Clin Exp Immunol ; 102(1): 217-23, 1995 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7554393

RESUMEN

IL-6, tumour necrosis factor-alpha (TNF-alpha) and IL-1 are thought to be the key mediators of the acute phase response although much of the evidence is based on in vitro studies. It is not clear to what extent each of the acute phase proteins are regulated in vivo by each of these cytokines. The aim of this study was to examine the effects of IL-6 treatment in eight patients with cancer on the concentrations of an extensive range of positive and negative acute phase proteins. It was part of a larger investigation to assess the value of IL-6 in the management of chemotherapy-induced thrombocytopenia. IL-6 was administered by a daily subcutaneous injection for 7 days at a dose level of 1, 3, or 10 micrograms/kg/day. Increases in the positive acute phase proteins, serum amyloid A, C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antichymotrypsin, haptoglobin, alpha 1-antitrypsin, fibrinogen, complement component C3, and caeruloplasmin, were observed, with the greatest incremental changes and fastest responses being seen for C-reactive protein and serum amyloid A protein. The negative acute phase proteins transferrin, transthyretin and retinol binding protein all fell to a nadir within 48-96 h after the first IL-6 injection. Increases in complement component C4 were only found in two patients, which may be related to the increase in circulating TNF-alpha concentrations found only in these patients. This study has therefore shown that IL-6 is capable of causing changes in the majority of acute phase proteins in vivo. Although secondary induction of TNF-alpha was not observed in the majority of patients examined, it is still possible however that other cytokines involved in regulation of the acute phase response, such as IL-1, may have been induced and contributed to the overall response.


Asunto(s)
Proteínas de Fase Aguda/biosíntesis , Interleucina-6/farmacología , Adulto , Complemento C4/biosíntesis , Femenino , Humanos , Inyecciones Subcutáneas , Interleucina-6/administración & dosificación , Masculino , Persona de Mediana Edad , Factor de Necrosis Tumoral alfa/farmacología
10.
Scand J Clin Lab Invest ; 52(2): 83-93, 1992 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1589701

RESUMEN

A double-blind randomized study comparing the effects of 1 year's treatment with atenolol (A) 50 mg or hydrochlorothiazide 25 mg plus amiloride 5 mg (Moduretic (M)) on the lipid profile was performed in 100 hypertensive men (mean age 47, range 22-64 years). After 4 weeks' wash-out and 4 weeks on placebo therapy subjects were randomized to either A or M therapy and followed up every third month for 1 year. If the diastolic blood pressure (DBP) was greater than or equal to 95 mmHg at a subsequent visit, the doses were doubled (n = 17 for A and n = 12 for M) and, if DBP was still greater than or equal to 95 mmHg on double dose, nifedipine 20 mg b.d. was added (n = 15 for A and n = 27 for M, p less than 0.05). The lowering of heart rate (p = 0.0001) and DBP (p = 0.005) was more pronounced with A after 1 year. During that time no significant treatment differences were noted for total cholesterol, low-density lipoprotein (LDL) cholesterol or apoproteins A and B. High-density lipoprotein (HDL) cholesterol decreased from a mean of 1.19 (+/- 0.36) mmol l-1 to 1.13 (+/- 0.35) with A, and increased from 1.14 (+/- 0.30) mmol l-1 to 1.22 (+/- 0.28) with M, and this treatment difference was significant (p = 0.0002). The triglycerides increased from 2.0 (+/- 1.2) mmol l-1 to 2.3 (+/- 1.6) in the A group and did not change with M treatment (p = 0.02) for treatment difference). In view of similar effects on cholesterol, LDL cholesterol and apoproteins, the prognostic importance of the observed treatment differences on HDL cholesterol and triglycerides remains to be established.


Asunto(s)
Amilorida/administración & dosificación , Atenolol/uso terapéutico , Hidroclorotiazida/administración & dosificación , Hipertensión/tratamiento farmacológico , Lípidos/sangre , Adulto , Apoproteínas/sangre , Quimioterapia Combinada , Humanos , Hipertensión/sangre , Recién Nacido , Lipoproteínas/sangre , Masculino , Persona de Mediana Edad
11.
Med Hypotheses ; 27(4): 313-6, 1988 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3226362

RESUMEN

The ultraviolet wavelengths in the sun's spectrum are known to be a basic cause of carcinomas of the skin. Since the skin as well as all body cavities, linings, and glands are composed of epithelial cells, it has been suggested that the ultraviolet bioluminescence and chemiluminescence which are emitted by bodily functions may be just as basic a cause of carcinomas within the body. Ninety percent of all human cancers are carcinomas. Bodily functions which emit a "normal" background of ultra-violet emission can be caused to emit higher, more dangerous levels and bursts of radiation by synergistic combinations of foods and chemicals. Damaging effects can also be increased by the sensitization of the epithelia to radiation by foods, dyes, drugs, medications, and prior irradiation. Certain foods and chemicals also produce serious damage at specific sites within the body. If the role of ultraviolet suggested here proves to be correct, an entirely new approach to the knowledge, prevention, and treatment of carcinomas becomes available.


Asunto(s)
Carcinoma/etiología , Modelos Biológicos , Neoplasias Inducidas por Radiación/etiología , Rayos Ultravioleta/efectos adversos , Daño del ADN , Epitelio/efectos de la radiación , Humanos , Mediciones Luminiscentes
12.
IEEE Trans Pattern Anal Mach Intell ; 9(5): 690-8, 1987 May.
Artículo en Inglés | MEDLINE | ID: mdl-21869428

RESUMEN

We introduce the Adaptive Hough Transform, AHT, as an efficient way of implementing the Hough Transform, HT, method for the detection of 2-D shapes. The AHT uses a small accumulator array and the idea of a flexible iterative "coarse to fine" accumulation and search strategy to identify significant peaks in the Hough parameter spaces. The method is substantially superior to the standard HT implementation in both storage and computational requirements. In this correspondence we illustrate the ideas of the AHT by tackling the problem of identifying linear and circular segments in images by searching for clusters of evidence in 2-D parameter spaces. We show that the method is robust to the addition of extraneous noise and can be used to analyze complex images containing more than one shape.

13.
Med Hypotheses ; 19(2): 155-9, 1986 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-3634907

RESUMEN

Carcinomas are the most common of human malignancies and occur in epithelial cells both in the skin and throughout the body. The ultraviolet wavelengths in solar radiation are accepted as the predominant cause of the DNA damage which results in skin cancer. These same ultraviolet wavelengths are emitted at all inner epithelial areas during normal bodily functions. It is suggested that DNA damage to epithelial cells caused by the absorption of ultraviolet radiation may be a basic cause of all carcinomas.


Asunto(s)
Carcinoma/etiología , Modelos Biológicos , Neoplasias Inducidas por Radiación , Rayos Ultravioleta , Animales , ADN/efectos de la radiación , Reparación del ADN , Digestión , Epitelio/efectos de la radiación , Enfermedades Genéticas Congénitas/complicaciones , Humanos , Neoplasias/patología
14.
Biochem J ; 224(1): 153-62, 1984 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-6095815

RESUMEN

The effects of 23 agonists on the rates of cellular 32P efflux and lactate dehydrogenase (LDH) release were tested in a perfused rat heart preparation which had been prelabelled in vitro with [32P]Pi. Some 13 compounds produced detectable changes at high doses within 10 min, and in most cases a polyphasic response was observed. Six classes of compound gave rise to substantial effects, as follows. Catecholamines and glucagon produced a transient initial stimulation of Pi efflux, followed by a long-term inhibition of Pi transport and an increased rate of LDH release. These effects were clearly different from the response seen after treatment with dibutyryl cyclic AMP, which had a slower, stimulatory, effect on Pi output in doses which gave rise to a pronounced inotropic effect, and produced a marked increase in both coronary flow and LDH release. Carbachol also gave rise to a large transient stimulation of Pi efflux, which was followed by smaller sustained increase in Pi output without any obvious effect on LDH release. Dibutyryl cyclic GMP had no effect on Pi efflux or LDH release. Insulin decreased the rate of Pi efflux, although the loss rate partially recovered towards the control value after prolonged exposure to the hormone. Insulin had no obvious inotropic effects and produced no change in the rate of LDH release. Corticosteroids increased the rate of Pi efflux, although the loss rate partially declined towards the control value with prolonged exposure to the hormones. Corticosteroids produced a very slight inotropic response, and large doses sometimes increased the rate of LDH release from the tissue. Aldosterone slightly stimulated Pi output. A small, transient and somewhat variable stimulation of Pi efflux was observed with vasopressin and angiotensin, whereas tri-iodothyronine was slightly inhibitory, but adenosine, histamine, spermidine, des-Asp1-angiotensin, prolactin, parathyroid substances, calcitonin and somatostatin had no significant effects under our experimental conditions. Ouabain stimulated Pi efflux in doses that had no detectable inotropic effect. It is suggested that Pi efflux involves the electroneutral transport of NaH2PO4 across the cardiac plasmalemma and that many of the hormonal effects might be explained by changes in the intracellular [Na+] and pH in addition to changes in the intracellular [Pi].


Asunto(s)
Hormonas/farmacología , Miocardio/metabolismo , Fosfatos/metabolismo , Animales , Bucladesina/farmacología , Carbacol/farmacología , Circulación Coronaria/efectos de los fármacos , Glucagón/farmacología , Corazón/efectos de los fármacos , Hidrocortisona/farmacología , Técnicas In Vitro , Insulina/farmacología , L-Lactato Deshidrogenasa/metabolismo , Masculino , Ratas , Ratas Endogámicas
15.
Biochem J ; 214(2): 317-23, 1983 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-6604525

RESUMEN

Rat polymorphonuclear leucocytes or neonatal-rat heart cells in culture were treated with 2'-deoxycoformycin and 5-iodotubercidin at concentrations that inhibited adenosine deaminase (EC 3.5.4.4) and adenosine kinase (EC 2.7.1.20) inside the intact cells, and the rate of adenosine accumulation was determined. The basal rate of adenosine formation was 2% (polymorphonuclear leucocytes) or 9% (heart cells) of the maximal activity of adenosine kinase also measured in intact cells. Greatly increased rates of adenosine formation were observed during adenine nucleotide catabolism. This condition also led to a decrease in adenosine kinase activity. When isolated rat hearts were perfused with 5-iodotubercidin alone at a concentration which inhibited adenosine kinase, no increase in tissue or perfusate adenosine or inosine concentration was observed. However, perfusion with hypoxic buffer or infusion of adenosine into the coronary circulation at a rate (20 nmol/min) equivalent to 40% of the activity of adenosine kinase caused large increases in effluent perfusate adenosine and inosine concentrations. These data argue unanimously against the existence of a substrate cycle controlling adenosine concentration. They suggest instead that an increase in the rate of adenosine formation is the principal cause of elevations in adenosine concentration during ATP catabolism.


Asunto(s)
Adenosina/metabolismo , Miocardio/metabolismo , Neutrófilos/metabolismo , Adenosina/biosíntesis , Adenosina Quinasa/antagonistas & inhibidores , Adenosina Quinasa/metabolismo , Animales , Células Cultivadas , Coformicina/análogos & derivados , Coformicina/farmacología , Corazón/efectos de los fármacos , Técnicas In Vitro , Masculino , Miocardio/citología , Neutrófilos/efectos de los fármacos , Pentostatina , Perfusión , Ratas , Ratas Endogámicas , Tubercidina/análogos & derivados , Tubercidina/farmacología
16.
Biochem J ; 195(1): 259-62, 1981 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-7306051

RESUMEN

Glass-electrode assemblies in which the reference half-cell contains a porous ceramic type of liquid junction are likely to produce misleading pH measurements under normal service conditions. The error arises from substantial liquid-junction potentials, associated with the porous ceramic plug, which vary with the ionic composition of the solution under test. The error is not revealed by conventional two-point calibration procedures, since the majority of standard buffer solutions have a similar total ionic strength, but will nevertheless be present when the unknown solution differs in ionic strength from the standardizing buffers. The size of the error is proportional to the ratio between the salt concentration in the standard buffers and the concentration present in the unknown solution, and varies from one electrode specimen to another. The fault was present in 24 out of 30 electrodes in normal use selected at random from seven laboratories, and the mean error was 0.2pH unit per 10-fold salt-concentration difference between standard and test solutions. It is estimated that errors of this order must be widespread in the recent literature. Older pH determinations are likely to be more reliable, since the original reference electrode design with a free-flowing liquid junction is apparently free from the artefact.


Asunto(s)
Concentración de Iones de Hidrógeno , Tampones (Química) , Electrodos/normas
17.
Biochem J ; 188(2): 297-11, 1980 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-7396864

RESUMEN

Pi uptake by a perfused rat heart preparation did not require the presence of any other permeant anion, but was markedly dependent on the extracellular Na+ concentration and accelerated when tissue oxygenation was inadequate. Pi efflux was also independent of other permeant anions, but apparently varied with the intracellular Na+ concentration. Cardiac Pi efflux was not sensitive to a number of inhibitors that clock Cl- movement in heart and other tissues. Both uptake and efflux apparently proceed via a reversible electroneutral co-transport system linked to the transmembrane Na+ gradient. Pi uptake was independent of cardiac work load, but the efflux rate was sharply accelerated after an increase in aortic pressure development, with a slow return towards basal values during sustained periods of high work output. An inverted biphasic effect on the efflux rate was observed after a reduction in cardiac work load. Mild hypoxia and respiratory and metabolic acidosis each resulted in a transient acceleration of Pi efflux followed by a return towards basal values during prolonged exposure to the stimulus, whereas respiratory and metabolic alkalosis produced a similar but inverted response. The origin of these phasic effects on Pi efflux remains to be identified at present.


Asunto(s)
Miocardio/metabolismo , Fosfatos/metabolismo , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-disulfónico/farmacología , Animales , Transporte Biológico/efectos de los fármacos , Furosemida/farmacología , Corazón/efectos de los fármacos , Hipoxia/metabolismo , Técnicas In Vitro , Iones/metabolismo , Cinética , Masculino , Nitroprusiato/farmacología , Perfusión , Esfuerzo Físico , Ratas
19.
Eur J Biochem ; 102(2): 625-36, 1979 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-230966

RESUMEN

Cardiac lactate production under aerobic conditions is absolutely dependent upon the availability of extracellular pyruvate. In the steady state, aerobic lactate output is largely independent of cardiac work load, but increases slightly when octanoate is included in addition to pyruvate in the perfusion fluid. Transient episodes of supra-normal lactate production are seen after sudden increases in cardiac work output, and also after transitions from octanoate to pyruvate in the perfusion media. These pulses of lactate production are invariably associated with the slow activation of pyruvate dehydrogenase in response to a sudden change in cardiac metabolic state, and they are abolished by pre-perfusion with dichloracetate, which converts pyruvate dehydrogenase into the fully active form. A second, additional component of the lactate pulses is sensitive to pre-perfusion with the transaminase inhibitor aminooxyacetate. The size of the second component is markedly dependent upon the precise protocol adopted for the experiment, and these variations suggest that the second component is associated with a major redistribution of cardiac Krebs' cycle intermediates and amino acids following the initial exposure to pyruvate-containing media. Steadystate aerobic lactate production is insensitive to both dichloroacetate and aminooxyacetate, and is thought to result from a direct exchange of malate for oxaloacetate across the heart mitochondrial membranes.


Asunto(s)
Lactatos/biosíntesis , Miocardio/metabolismo , Aerobiosis , Ácido Aminooxiacético/farmacología , Animales , Caprilatos/metabolismo , Ácido Dicloroacético/farmacología , Corazón/efectos de los fármacos , Cinética , Masculino , NAD/metabolismo , Perfusión , Complejo Piruvato Deshidrogenasa/metabolismo , Piruvatos/metabolismo , Ratas
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