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1.
Br J Clin Pharmacol ; 2020 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-33289121

RESUMEN

Glucocorticoids are highly effective medicines in the treatment of inflammatory disorders. However they cause severe adverse reactions, particularly where taken at high doses systemically for prolonged periods. Systemic glucocorticoids are therefore given at dosage sufficient to control the disease, then withdrawn as fast as is possible to minimise dose- and time-related adverse drug reactions without losing disease control. Adverse withdrawal reactions present a major challenge in the withdrawal of long term glucocorticoids. Suppression of the hypothalamic-pituitary-adrenal (HPA) axis causes adrenal insufficiency, which is potentially life threatening and can become symptomatic as treatment is withdrawn. Adrenal insufficiency can be extremely difficult to differentiate from 'glucocorticoid withdrawal syndrome', where patients experience symptoms despite adequate adrenal function, and from psychological dependence. Long term systemic glucocorticoids should therefore be withdrawn slowly. The rate at which the dose is tapered should initially be determined by treatment requirements of the underlying disease. Once 'physiological' doses are reached, the rate of reduction is determined by rate of HPA recovery and need for exogenous glucocorticoid cover while endogenous secretion recovers. If symptoms prevent treatment withdrawal, HPA testing should be used to look for adrenal insufficiency. Patients with adrenal insufficiency require 'physiological' doses of glucocorticoids for adrenal replacement, which may be lifelong if the HPA axis fails to recover.

2.
PLoS One ; 15(1): e0227175, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31923188

RESUMEN

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is associated with an increased risk of myocardial infarction and stroke but it remains unclear how to identify microvascular changes in this population. OBJECTIVES: We hypothesized that simple non-mydriatic retinal photography is feasible and can be used to assess microvascular damage in COPD. METHODS: Novel Vascular Manifestations of COPD was a prospective study comparing smokers with and without COPD, matched for age. Non-mydriatic, retinal fundus photographs were assessed using semi-automated software. RESULTS: Retinal images from 24 COPD and 22 control participants were compared. Cases were of similar age to controls (65.2 vs. 63.1 years, p = 0.38), had significantly lower Forced Expiratory Volume in one second (FEV1) (53.4 vs 100.1% predicted; p < 0.001) and smoked more than controls (41.7 vs. 29.6 pack years; p = 0.04). COPD participants had wider mean arteriolar (155.6 ±15 uM vs. controls [142.2 ± 12 uM]; p = 0.002) and venular diameters (216.8 ±20.7 uM vs. [201.3± 19.1 uM]; p = 0.012). Differences in retinal vessel caliber were independent of confounders, odds ratios (OR) = 1.08 (95% confidence intervals [CI] = 1.02, 1.13; p = 0.007) and OR = 1.05 (CI = 1.01, 1.09; p = 0.011) per uM increase in arteriolar and venular diameter respectively. FEV1 remained significantly associated with retinal vessel dilatation r = -0.39 (p = 0.02). CONCLUSIONS: Non-mydriatic retinal imaging is easily facilitated. We found significant arteriole and venous dilation in COPD compared to age-matched smokers without COPD associated with lung function independent of standard cardiovascular risk factors. Retinal microvascular changes are known to be strongly associated with future vascular events and retinal photography offers potential to identify this risk. TRIAL REGISTRATION: clinicaltrials.gov NCT02060292.


Asunto(s)
Procesamiento de Imagen Asistido por Computador/métodos , Microvasos/diagnóstico por imagen , Fotomicrografía/métodos , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedades de la Retina/diagnóstico por imagen , Enfermedades de la Retina/etiología , Vasos Retinianos/diagnóstico por imagen , Adulto , Anciano , Estudios de Casos y Controles , Estudios de Factibilidad , Femenino , Fondo de Ojo , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Vasos Retinianos/patología , Fumadores , Fumar/efectos adversos
3.
Curr Oncol ; 26(3): e346-e356, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31285679

RESUMEN

Introduction: Total pancreatectomy for pancreatic ductal adenocarcinoma has historically been associated with substantial patient morbidity and mortality. Given advancements in perioperative and postoperative care, evaluation of the surgical treatment options for pancreatic adenocarcinoma should consider patient outcomes and long-term survival for total pancreatectomy compared with partial pancreatectomy. Methods: The U.S. National Cancer Database was queried for patients undergoing total pancreatectomy or partial pancreatectomy for pancreatic adenocarcinoma during 1998-2006. Demographics, tumour characteristics, operative outcomes, 30-day mortality, 30-day readmission, additional treatment, and Kaplan-Meier survival curves were compared. Results: The database query returned 807 patients who underwent total pancreatectomy and 5840 who underwent partial pancreatectomy. More patients who underwent total pancreatectomy than a partial pancreatectomy had a margin-negative resection (p < 0.0001). Mortality and readmission rates were similar in the two groups, as was long-term survival on Kaplan-Meier curves (p = 0.377). A statistically significant difference in the rate of surgery only (without additional treatment) was observed for patients in the total pancreatectomy group (p = 0.0003). Conclusions: Although total compared with partial pancreatectomy was associated with a higher rate of margin-negative resection, median survival was not significantly different for patients undergoing either procedure. Patients who underwent total pancreatectomy were significantly less likely to receive adjuvant therapy.


Asunto(s)
Adenocarcinoma/cirugía , Pancreatectomía/métodos , Neoplasias Pancreáticas/cirugía , Adenocarcinoma/mortalidad , Adenocarcinoma/patología , Anciano , Bases de Datos Factuales , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Márgenes de Escisión , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Pancreáticas/mortalidad , Neoplasias Pancreáticas/patología , Readmisión del Paciente , Estados Unidos
4.
AJNR Am J Neuroradiol ; 38(2): 376-382, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27765741

RESUMEN

BACKGROUND AND PURPOSE: Infantile neuronal ceroid lipofuscinosis is a devastating neurodegenerative storage disease caused by palmitoyl-protein thioesterase 1 deficiency, which impairs degradation of palmitoylated proteins (constituents of ceroid) by lysosomal hydrolases. Consequent lysosomal ceroid accumulation leads to neuronal injury, resulting in rapid neurodegeneration and childhood death. As part of a project studying the treatment benefits of a combination of cysteamine bitartrate and N-acetyl cysteine, we made serial measurements of patients' brain volumes with MR imaging. MATERIALS AND METHODS: Ten patients with infantile neuronal ceroid lipofuscinosis participating in a treatment/follow-up study underwent brain MR imaging that included high-resolution T1-weighted images. After manual placement of a mask delineating the surface of the brain, a maximum-likelihood classifier was applied to determine total brain volume, further subdivided as cerebrum, cerebellum, brain stem, and thalamus. Patients' brain volumes were compared with those of a healthy population. RESULTS: Major subdivisions of the brain followed similar trajectories with different timing. The cerebrum demonstrated early, rapid volume loss and may never have been normal postnatally. The thalamus dropped out of the normal range around 6 months of age; the cerebellum, around 2 years of age; and the brain stem, around 3 years of age. CONCLUSIONS: Rapid cerebral volume loss was expected on the basis of previous qualitative reports. Because our study did not include a nontreatment arm and because progression of brain volumes in infantile neuronal ceroid lipofuscinosis has not been previously quantified, we could not determine whether our intervention had a beneficial effect on brain volumes. However, the level of quantitative detail in this study allows it to serve as a reference for evaluation of future therapeutic interventions.


Asunto(s)
Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Lipofuscinosis Ceroideas Neuronales/diagnóstico por imagen , Acetilcisteína/uso terapéutico , Envejecimiento/patología , Tronco Encefálico/diagnóstico por imagen , Cerebelo/diagnóstico por imagen , Cerebro/diagnóstico por imagen , Niño , Preescolar , Cisteamina/uso terapéutico , Electroencefalografía , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Lipofuscinosis Ceroideas Neuronales/tratamiento farmacológico , Tálamo/diagnóstico por imagen
5.
Int J Med Robot ; 12(3): 554-60, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26202591

RESUMEN

BACKGROUND: Robotic pancreaticoduodenectomy (RP) has shown some advantages over open pancreaticoduodenectomy (OP) but no data has been published providing a cost comparison. METHODS: Retrospective analysis of all pancreaticoduodenectomies at a single quaternary cancer referral center was performed. Patient demographics, comorbidities, operative characteristics, complications, and charge data were recorded, and then compared using standard statistical methods. RESULTS: 71 pancreaticoduodenectomies were performed: 22 RP and 49 OP. Patients undergoing OP had similar demographics, comorbidities, pathology, and oncologic characteristics as patients undergoing RP. While operative charges were higher for RP, once inpatient stay associated costs and follow-up costs were included, there was no difference in total costs between RP and OP. CONCLUSIONS: Patients undergoing RP have equivalent rates of R0 resection as OP, and benefit from decreased number of complications, surgical site infections, and length of stay in the intensive care unit. Once cost of complications and follow-up are incorporated, no significant difference between procedures exists. Copyright © 2015 John Wiley & Sons, Ltd.


Asunto(s)
Pancreaticoduodenectomía/efectos adversos , Procedimientos Quirúrgicos Robotizados/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Costos de la Atención en Salud , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Pancreaticoduodenectomía/economía , Estudios Retrospectivos , Procedimientos Quirúrgicos Robotizados/economía
7.
AJNR Am J Neuroradiol ; 36(1): 194-201, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25190203

RESUMEN

BACKGROUND: Bilateral infarcts confined to the globus pallidus are unusual and occur in conjunction with only a few disorders, including isolated methylmalonic acidemia, a heterogeneous inborn error of metabolism. On the basis of neuroradiographic features of metabolic strokes observed in a large cohort of patients with methylmalonic acidemia, we have devised a staging system for methylmalonic acidemia-related globus pallidus infarcts. MATERIALS AND METHODS: Forty patients with isolated methylmalonic acidemia and neurologic symptoms underwent clinical brain MR imaging studies, which included 3D-T1WI. Infarcted globus pallidus segments were neuroanatomically characterized, and infarct volumes were measured. RESULTS: Globus pallidus infarcts were present in 19 patients; all were bilateral, and most were left-dominant. A neuroanatomic scoring system based on the infarct patterns was devised; this revealed a 5-stage hierarchical susceptibility to metabolic infarct, with the posterior portion of the globus pallidus externa being the most vulnerable. Globus pallidus infarct prevalence by methylmalonic acidemia class was the following: cblA (5/7, 71%), cblB (3/7, 43%), mut(o) (10/22, 45%), and mut- (1/4, 25%). Tiny lacunar infarcts in the pars reticulata of the substantia nigra, previously unrecognized in methylmalonic acidemia, were found in 17 patients, 13 of whom also had a globus pallidus infarct. CONCLUSIONS: The staged pattern of globus pallidus infarcts in isolated methylmalonic acidemia suggests a nonuniform, regionally specific cellular susceptibility to metabolic injury, even for patients having milder biochemical phenotypes. In support of this hypothesis, the delineation of lacunar infarcts in the pars reticulata of the substantia nigra, a tissue functionally and histologically identical to the globus pallidus interna, supports the concept of cell-specific pathology.


Asunto(s)
Errores Innatos del Metabolismo de los Aminoácidos/complicaciones , Infarto Encefálico/etiología , Infarto Encefálico/patología , Globo Pálido/patología , Estudios de Cohortes , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino
9.
Neurology ; 71(24): 1973-80, 2008 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-19064878

RESUMEN

BACKGROUND: Autosomal dominant partial epilepsy with auditory features (ADPEAF) is an idiopathic focal epilepsy syndrome with auditory symptoms or receptive aphasia as major ictal manifestations, frequently associated with mutations in the leucine-rich, glioma inactivated 1 (LGI1) gene. Although affected subjects do not have structural abnormalities detected on routine MRI, a lateral temporal malformation was identified through high resolution MRI in one family. We attempted to replicate this finding and to assess auditory and language processing in ADPEAF using fMRI and magnetoencephalography (MEG). METHODS: We studied 17 subjects (10 affected mutation carriers, 3 unaffected carriers, 4 noncarriers) in 7 ADPEAF families, each of which had a different LGI1 mutation. Subjects underwent high-resolution structural MRI, fMRI with an auditory description decision task (ADDT) and a tone discrimination task, and MEG. A control group comprising 26 volunteers was also included. RESULTS: We found no evidence of structural abnormalities in any of the 17 subjects. On fMRI with ADDT, subjects with epilepsy had significantly less activation than controls. On MEG with auditory stimuli, peak 2 auditory evoked field latency was significantly delayed in affected individuals compared to controls. CONCLUSIONS: These findings do not support the previous report of a lateral temporal malformation in autosomal dominant partial epilepsy with auditory features (ADPEAF). However, our fMRI and magnetoencephalography data suggest that individuals with ADPEAF have functional impairment in language processing.


Asunto(s)
Corteza Auditiva/fisiopatología , Percepción Auditiva/genética , Epilepsias Parciales/complicaciones , Trastornos del Lenguaje/fisiopatología , Percepción del Habla/genética , Estimulación Acústica , Adulto , Corteza Auditiva/patología , Mapeo Encefálico , Trastornos de los Cromosomas/complicaciones , Trastornos de los Cromosomas/genética , Epilepsias Parciales/genética , Femenino , Lateralidad Funcional/genética , Genes Dominantes/genética , Humanos , Péptidos y Proteínas de Señalización Intracelular , Trastornos del Lenguaje/genética , Trastornos del Lenguaje/patología , Pruebas del Lenguaje , Imagen por Resonancia Magnética , Magnetoencefalografía , Masculino , Mutación/genética , Proteínas/genética , Tiempo de Reacción/genética
10.
Thorax ; 61(4): 284-9, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16449265

RESUMEN

BACKGROUND: Hyperglycaemia is associated with poor outcomes from pneumonia, myocardial infarction and stroke, but the effect of blood glucose on outcomes from acute exacerbations of chronic obstructive pulmonary disease (AECOPD) has not been established. Recent UK guidelines do not comment on measurement or control of blood glucose in AECOPD. A study was therefore undertaken to determine the relationship between blood glucose concentrations, length of stay in hospital, and mortality in patients admitted with AECOPD. METHODS: Data were retrieved from electronic records for patients admitted with AECOPD with lower respiratory tract infection in 2001-2. The patients were grouped according to blood glucose quartile (group 1, <6 mmol/l (n = 69); group 2, 6.0-6.9 mmol/l (n = 69); group 3, 7.0-8.9 mmol/l (n = 75); and group 4, >9.0 mmol/l (n = 71)). RESULTS: The relative risk (RR) of death or long inpatient stay was significantly increased in group 3 (RR 1.46, 95% CI 1.05 to 2.02, p = 0.02) and group 4 (RR 1.97, 95% CI 1.33 to 2.92, p < 0.0001) compared with group 1. For each 1 mmol/l increase in blood glucose the absolute risk of adverse outcomes increased by 15% (95% CI 4 to 27), p = 0.006. The risk of adverse outcomes increased with increasing hyperglycaemia independent of age, sex, a previous diagnosis of diabetes, and COPD severity. Isolation of multiple pathogens and Staphylococcus aureus from sputum also increased with increasing blood glucose. CONCLUSION: Increasing blood glucose concentrations are associated with adverse clinical outcomes in patients with AECOPD. Tight control of blood glucose reduces mortality in patients in intensive care or following myocardial infarction. A prospective study is now required to determine whether control of blood glucose can also improve outcomes from AECOPD.


Asunto(s)
Hiperglucemia/complicaciones , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedad Aguda , Anciano , Glucemia/metabolismo , Femenino , Hospitalización , Humanos , Hiperglucemia/mortalidad , Masculino , Pronóstico , Enfermedad Pulmonar Obstructiva Crónica/sangre , Enfermedad Pulmonar Obstructiva Crónica/mortalidad , Factores de Riesgo , Espirometría , Esputo/microbiología
11.
Thorax ; 60(9): 761-4, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16135681

RESUMEN

BACKGROUND: The risk of nosocomial infection is increased in critically ill patients by stress hyperglycaemia. Glucose is not normally detectable in airway secretions but appears as blood glucose levels exceed 6.7-9.7 mmol/l. We hypothesise that the presence of glucose in airway secretions in these patients predisposes to respiratory infection. METHODS: An association between glucose in bronchial aspirates and nosocomial respiratory infection was examined in 98 critically ill patients. Patients were included if they were expected to require ventilation for more than 48 hours. Bronchial aspirates were analysed for glucose and sent twice weekly for microbiological analysis and whenever an infection was suspected. RESULTS: Glucose was detected in bronchial aspirates of 58 of the 98 patients. These patients were more likely to have pathogenic bacteria than patients without glucose detected in bronchial aspirates (relative risk 2.4 (95% CI 1.5 to 3.8)). Patients with glucose were much more likely to have methicillin resistant Staphylococcus aureus (MRSA) than those without glucose in bronchial aspirates (relative risk 2.1 (95% CI 1.2 to 3.8)). Patients who became colonised or infected with MRSA had more infiltrates on their chest radiograph (p<0.001), an increased C reactive protein level (p<0.05), and a longer stay in the intensive care unit (p<0.01). Length of stay did not determine which patients acquired MRSA. CONCLUSION: The results imply a relationship between the presence of glucose in the airway and a risk of colonisation or infection with pathogenic bacteria including MRSA.


Asunto(s)
Glucosa/análisis , Resistencia a la Meticilina , Infecciones del Sistema Respiratorio/diagnóstico , Infecciones Estafilocócicas/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Líquido del Lavado Bronquioalveolar/química , Líquido del Lavado Bronquioalveolar/microbiología , Cuidados Críticos , Enfermedad Crítica , Infección Hospitalaria/diagnóstico , Infección Hospitalaria/microbiología , Femenino , Humanos , Hiperglucemia/etiología , Intubación Intratraqueal/efectos adversos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Respiración Artificial/efectos adversos , Infecciones del Sistema Respiratorio/tratamiento farmacológico , Infecciones del Sistema Respiratorio/microbiología , Factores de Riesgo , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiología , Estrés Fisiológico/etiología
12.
Emerg Med J ; 22(8): 556-7, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16046755

RESUMEN

Rhinorrhoea is a clinical sign of cerebrospinal fluid (CSF) leakage in patients with skull fracture, but can also be attributable to respiratory secretions or tears. Laboratory tests confirming the presence of CSF are not sufficiently rapid to support clinical decision making in the emergency department and may not be universally available. Detection of glucose in nasal discharge was traditionally used to diagnose CSF leak at the bedside, but has fallen into disuse as it has poor positive predictive value. We propose an algorithm to improve the diagnostic value of this test taking into consideration factors we have found to affect the glucose concentration of respiratory secretions. In patients at risk of CSF leak, nasal discharge is likely to contain CSF if glucose is present in the absence of visible blood, if blood glucose is <6 mmol x L(-1), and if there are no symptoms of upper respiratory tract infection.


Asunto(s)
Algoritmos , Rinorrea de Líquido Cefalorraquídeo/diagnóstico , Glucosa Oxidasa , Glucosa/líquido cefalorraquídeo , Glucemia/análisis , Rinorrea de Líquido Cefalorraquídeo/líquido cefalorraquídeo , Rinorrea de Líquido Cefalorraquídeo/etiología , Traumatismos Craneocerebrales/complicaciones , Humanos , Moco/química , Tiras Reactivas
13.
Tob Control ; 14(2): 141-2, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15791025

RESUMEN

Life time smoking of ready made cigarettes can be readily quantified as "pack years" smoked, but methods for measuring loose tobacco use are less well established. In this study the frequency of loose tobacco use by 247 hospital in-patients was determined; 64% were current or ex-smokers, 41.3% of whom (25.9% of participants) had smoked loose tobacco. A formula was developed for converting loose tobacco use to pack years smoked, based on the weight of tobacco in ready made cigarettes; 12.5 g or half an ounce of loose tobacco was approximately equivalent to one packet of 20 cigarettes. Using a questionnaire it was found that hospital physicians of all grades were able to convert smoking histories of ready made cigarettes, but not loose tobacco, into number of "pack years" smoked.


Asunto(s)
Nicotiana , Fumar/epidemiología , Femenino , Hospitalización , Humanos , Masculino , Persona de Mediana Edad , Distribución por Sexo
14.
Pflugers Arch ; 444(4): 476-83, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12136266

RESUMEN

In rat distal colon, aldosterone has little effect on Na(+) channel (ENaC) alpha-subunit levels but increases the expression of the beta- and gamma-subunits and stimulates electrogenic Na(+) transport. By contrast, the molecular basis of aldosterone's inability to stimulate electrogenic Na(+) transport in the proximal colon is unclear. We therefore compared the effects of hyperaldosteronism secondary to 10 days dietary Na(+) depletion on ENaC subunit expression in rat proximal and distal colon. Northern analyses revealed appreciable and similar levels of alpha-subunit mRNA throughout the colon in control and Na(+)-depleted animals. By contrast, Na(+) depletion substantially enhanced beta-subunit mRNA expression in the distal colon, but had no effect on the low expression levels of beta-subunit mRNA in the proximal colon. Expression of the gamma-subunit, evaluated by PCR, was also restricted to the distal colon of Na(+)-depleted animals. Western analyses demonstrated similar levels of alpha-subunit protein in the proximal and distal colon of both groups of animals, whereas beta-subunit and gamma-subunit proteins were detected solely or predominantly in the distal colon of the Na(+)-depleted animals. Immunocytochemistry confirmed that significant levels of all three subunit proteins only occurred in the apical membrane of surface cells in the distal colon of Na(+)-depleted animals. Our findings are consistent with previous studies demonstrating that aldosterone stimulates electrogenic Na(+) transport in rat distal colon by increasing the expression of beta- and gamma-subunit mRNA and protein, and thus the amount of functional heteromeric ENaC protein in the apical domain. They also show that aldosterone is incapable of stimulating electrogenic Na(+) transport in rat proximal colon (despite the presence of alpha-subunit mRNA and protein) because of its inability to enhance beta- and gamma-subunit expression in this segment.


Asunto(s)
Colon/metabolismo , Dieta Hiposódica , Regulación de la Expresión Génica , Canales de Sodio/biosíntesis , Canales de Sodio/genética , Animales , Northern Blotting , Western Blotting , Canales Epiteliales de Sodio , Regulación de la Expresión Génica/fisiología , Hiperaldosteronismo/metabolismo , Inmunohistoquímica , Masculino , Reacción en Cadena de la Polimerasa , Subunidades de Proteína/biosíntesis , Subunidades de Proteína/genética , ARN Mensajero/análisis , Ratas , Ratas Sprague-Dawley
16.
J Hypertens ; 19(9): 1595-600, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11564979

RESUMEN

BACKGROUND: Several studies in isolated cells have reported that intracellular pH (pHi) in individuals with essential hypertension may be relatively alkaline compared to normotensive individuals. Such an abnormality of pHi in hypertension would be consistent with enhanced sodium-hydrogen exchanger activity and may provide potential mechanisms by which hypertension and its complications could develop. OBJECTIVES: To determine in-vivo intracellular pH of skeletal muscle at rest and during recovery from exercise-induced acidosis in hypertensive and normotensive subjects. METHODS: Using 31-phosphorus magnetic resonance spectroscopy, pHi of the dominant flexor digitorum superficialis was measured in 20 Caucasian subjects (14 male) with essential hypertension and 20 normotensive controls matched for gender, age, race and body mass index. Measurements were made at rest and during the exercise and recovery periods of a stepped incremental maximal exercise protocol. The rate of pHi recovery from exercise-induced acidosis was calculated by linear regression over the first 210 s of recovery from the pHi time plots of respective subjects. RESULTS: Mean resting pHi in the hypertensive (7.05 +/- 0.04) and normotensive groups (7.06 +/- 0.04) were not significantly different. There was a significant effect of gender on pHi: mean pHi was 7.07 +/- 0.03 in males and 7.02 +/- 0.03 in females, respectively (P < 0.0005). The mean intracellular pH achieved by exercise was 6.74 +/- 0.31 in hypertensive individuals and not significantly different in normotensive individuals (6.68 +/- 0.19; P = 0.4). The mean rate of pHi recovery in the hypertensives was 0.08 +/- 0.03 pH units/min and not significantly different in normotensives (0.08 +/- 0.02; P = 0.4). CONCLUSIONS: These results contrast with previously documented abnormalities in the control of pHi in hypertension and demonstrate the absence of major in-vivo disturbances of pHi in skeletal muscle, both at rest and during recovery from exercise-induced acidosis, in essential hypertension. Therefore, it is possible that previously documented abnormalities of pHi and activity of the exchanger may be either specific to cell type or not present under in-vivo conditions.


Asunto(s)
Ejercicio Físico/fisiología , Hidrógeno/metabolismo , Hipertensión/metabolismo , Membranas Intracelulares/metabolismo , Músculo Esquelético/metabolismo , Femenino , Humanos , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Masculino , Persona de Mediana Edad , Fósforo , Valores de Referencia , Descanso , Caracteres Sexuales
17.
J Hum Hypertens ; 15(6): 425-30, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11439319

RESUMEN

Polymorphisms of the epithelial sodium channel may raise blood pressure by increasing renal sodium reabsorption. This study examines frequency distributions and associations with hypertension of the T594M and of the G442V polymorphisms of the beta subunit of the epithelial sodium channel in a population-based sample. We studied a stratified random sample of 459 subjects (279 women), aged 40-59 years, of black African origin from general practices' lists within a defined area of South London. All were first generation immigrants. The polymorphic variants were detected using single strand conformational polymorphism technique (SSCP). The prevalence of hypertension (BP > or =160 and/or 95 mm Hg or on drug therapy) was 43%; of these, 76% were on drug therapy. The main analysis was carried out by three ordered blood pressure categories (I to III) according to increasing blood pressure and presence or absence of drug therapy. The frequency of the 594M variant (heterozygotes and homozygotes) was 4.6%; the frequency of the 442V variant was higher (27.0%). The frequency of the 594M variant increased with increasing blood pressure category (P = 0.05) and was more common in hypertensives than normotensives. By contrast the frequency of the 442V variant did not vary across increasing blood pressure categories (P = 0.62). No gender difference was observed. Adjustment for age, sex and body mass index did not alter these findings. These results suggest that the 594M variant may contribute to high blood pressure in black people of African origin whereas the G442V polymorphism is unlikely to influence blood pressure in this population.


Asunto(s)
Población Negra/genética , Hipertensión/etnología , Hipertensión/genética , Polimorfismo Genético/genética , Canales de Sodio/genética , Adulto , Presión Sanguínea/genética , Intervalos de Confianza , Estudios Transversales , Femenino , Humanos , Hipertensión/diagnóstico , Londres/epidemiología , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Prevalencia
18.
Hypertension ; 38(1): 76-80, 2001 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-11463763

RESUMEN

Salt-sensitive hypertension is more common and has more severe consequences in urban black populations than in white populations. Increased renal sodium reabsorption through epithelial sodium channels may underlie the development of high blood pressure in black people. Increased sodium channel activity has been detected in subjects with Liddle's syndrome by nasal potential difference measurements. Nasal potential difference measurements were made in 39 black normotensive, 106 black hypertensive, 51 white normotensive, and 61 white hypertensive subjects. Blood pressure, body mass index, and 24-hour urinary sodium excretion were also measured. Maximum potential difference was significantly higher in black subjects than in white subjects (P=0.009) but was not significantly different between normotensive and hypertensive subjects after adjustment for age, gender, current smoking status, body mass index, and 24-hour urinary sodium excretion (black normotensive, -21.6+/-1.0 mV; black hypertensive, -21.5+/-0.7 mV; white normotensive, -18.5+/-1.0 mV; and white hypertensive subjects, -18.9+/-0.9 mV). Nasal potential difference did not correlate with blood pressure or biochemical variables within ethnic and blood pressure groups. Nasal potential difference, an index of nasal sodium channel activity, is greater in black than in white people but does not differ between normotensive and hypertensive groups. Increased nasal potential difference measurements may reflect generalized upregulation of sodium transport in black people compared with white people, which may help to explain the high prevalence of hypertension in black people but would not explain differences in blood pressure within separate ethnic groups.


Asunto(s)
Células Epiteliales/fisiología , Hipertensión/metabolismo , Canales de Sodio/metabolismo , Sodio/metabolismo , Absorción/fisiología , Adulto , Negro o Afroamericano , Análisis de Varianza , Población Negra , Presión Sanguínea , Células Epiteliales/metabolismo , Femenino , Humanos , Hipertensión/etnología , Hipertensión/patología , Masculino , Potenciales de la Membrana , Canales de Sodio/fisiología
19.
Clin Sci (Lond) ; 100(3): 327-33, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11222120

RESUMEN

Salt-sensitive hypertension is common in people of African origin, and may be caused by increased transepithelial sodium absorption. The pH of nasal secretions is negatively correlated with the difference in Na(+) concentration between nasal secretions and plasma, and may be a marker of transepithelial sodium absorption. Nasal pH was measured using a probe sited under the inferior turbinate. Measurements of nasal pH were reproducible, with a coefficient of variation of 3.3% for repeated measurements on the same day and of 2.7% between measurements on different days. Nasal pH did not correlate with nasal potential difference, a measure of transepithelial sodium absorption. Nasal pH was significantly lower in 89 black individuals (24 normotensive and 65 hypertensive) than in 51 white individuals (26 normotensive and 25 hypertensive) (black normotensive. 6.44+/-0.08; black hypertensive, 6.62+/-0.05; white normotensive, 6.91+/-0.06; white hypertensive, 6.98+/-0.06), after adjustment for age, gender, current smoking status, body mass index and 24 h urinary sodium excretion (P=0.002), but was not significantly different between the normotensive and hypertensive individuals. Nasal pH was more acidic in black than in white individuals, which may represent generalized up-regulation of sodium transport in black people. However, the lack of correlation between nasal pH and potential difference suggests that nasal pH is, at best, only weakly related to transepithelial sodium absorption. Ethnic differences in nasal pH may be of direct relevance in the airways, as many of the functions of airway surface liquid are dependent on pH.


Asunto(s)
Población Negra , Hipertensión/etnología , Mucosa Nasal/química , Población Blanca , Absorción , Adulto , Análisis de Varianza , Estudios de Casos y Controles , Femenino , Humanos , Concentración de Iones de Hidrógeno , Hipertensión/metabolismo , Masculino , Potenciales de la Membrana , Persona de Mediana Edad , Mucosa Nasal/metabolismo , Reproducibilidad de los Resultados , Fumar/etnología , Fumar/metabolismo , Sodio/farmacocinética
20.
Br J Clin Pharmacol ; 49(3): 185-98, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10718773

RESUMEN

Ion channels exist in all cells and are enormously varied in structure, function and regulation. Some progress has been made in understanding the role that ion channels play in the control of blood pressure, but the discipline is still in its infancy. Ion channels provide many different targets for intervention in disorders of blood pressure and exciting advances have been made in this field. It is possible that new drugs, as well as antisense nucleotide technology or gene therapy directed towards ion channels, may form a new class of treatments for high and low blood pressure in the future.


Asunto(s)
Presión Sanguínea/fisiología , Canales Iónicos/fisiología , Bloqueadores de los Canales de Calcio/uso terapéutico , Humanos , Hipertensión/tratamiento farmacológico , Activación del Canal Iónico/fisiología , Canales Iónicos/química , Transporte Iónico/fisiología , Músculo Liso/efectos de los fármacos , Conformación Proteica
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