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1.
Clin Med (Lond) ; 24(2): 100028, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38387536

RESUMEN

BACKGROUND: Acute kidney injury (AKI) is a common complication of hospitalisations. This national audit assessed the care received by patients with AKI in hospital Trusts in England and Wales. METHODS: Twenty four hospital Trusts across England and Wales took part. Patients with AKI stage2/3 were identified using the UK Renal Registry AKI master patient index. Data was returned through a secure portal with linkage to hospital episode statistic mortality and hospitalisation data. Completion rates of AKI care standards and regional variations in care were established. RESULTS: 989 AKI episodes were included in the analyses. In-hospital 30-day mortality was 31-33.1% (AKI 2/3). Standard AKI interventions were completed in >80% of episodes. Significant inter-hospital variation remained in attainment of AKI care standards after adjustment for age and sex. Recording of urinalysis (41.9%) and timely imaging (37.2%) were low. Information on discharge summaries relating to medication changes/re-commencement and follow-up blood tests associated with reduced mortality. No quality indicators relating to clinical management associated with mortality. Better communication on discharge summaries associated with reduced mortality. CONCLUSIONS: Outcomes for patients with AKI in hospital remain poor. Regional variation in care exists. Work is needed to assess whether improving and standardising care improves patient outcomes.


Asunto(s)
Lesión Renal Aguda , Humanos , Gales/epidemiología , Lesión Renal Aguda/terapia , Lesión Renal Aguda/mortalidad , Inglaterra/epidemiología , Masculino , Femenino , Anciano , Persona de Mediana Edad , Anciano de 80 o más Años , Auditoría Médica , Mortalidad Hospitalaria , Adulto
2.
J Dairy Sci ; 100(4): 2944-2953, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28131570

RESUMEN

The availability of reliable tools to enable the sensitive and specific detection of mastitis in dairy cows can assist in developing control strategies and promote the more rational use of antibiotics. We have developed a milk cathelicidin ELISA that shows high sensitivity and specificity for dairy cow mastitis, based on latent class analysis. In this study, we investigated the effect of microbial agents on cathelicidin abundance in the milk of cows with clinical mastitis. We subjected 535 quarter milk samples (435 from quarters showing signs of clinical mastitis and 100 from healthy quarters as a control) to milk cathelicidin ELISA, somatic cell count (SCC), and microbiologic culture. Of the 435 clinical mastitis samples, 431 (99.08%) were positive for cathelicidin, 424 (97.47%) had SCC >200,000 cells/mL, and 376 (86.44%) were culture-positive. Of the 59 culture-negative samples, 58 (98.30%) were positive for cathelicidin and 55 (93.22%) had SCC >200,000 cells/mL. The abundance of cathelicidin and the extent of SCC increase depended on the causative agent: Streptococcus agalactiae and coagulase-negative staphylococci showed the highest and lowest changes, respectively. We also observed differences in behavior between the 2 markers depending on the pathogen: Streptococcus agalactiae induced the highest cathelicidin abundance, and Serratia spp. induced the highest SCC. Nevertheless, the different ability of microorganisms to induce cathelicidin release in milk did not compromise its value as a mastitis marker, given its higher sensitivity compared to SCC or microbiologic culture. All 100 negative control samples (collected from healthy quarters with SCC <100,000 cells/mL and culture-negative) were also negative for cathelicidin, corresponding to 100% specificity in the evaluated sample cohort. This study confirmed the value of the milk cathelicidin ELISA for detecting bovine mastitis, and highlighted the influence of mastitis-causing microorganisms on cathelicidin abundance. This influence did not compromise diagnostic performance; instead, it may have better reflected disease severity and evolution than SCC.


Asunto(s)
Mastitis Bovina/microbiología , Leche/química , Animales , Antibacterianos/uso terapéutico , Péptidos Catiónicos Antimicrobianos , Bovinos , Recuento de Células/veterinaria , Femenino , Staphylococcus , Catelicidinas
3.
J Dairy Sci ; 100(1): 608-619, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27865508

RESUMEN

In this study we investigated the circulation of methicillin-resistant Staphylococcus aureus (MRSA) in 2 dairy cattle farms (farm A and B), previously identified as MRSA-positive in bulk tank milk samples, and epidemiologically related to swine farms. Collected specimens included quarter milk samples and nasal swabs from dairy cows, pig nasal swabs collected at both the farm and slaughterhouse level, environmental dust samples, and human nasal swabs from the farms' owners and workers. The prevalence of MRSA was estimated at the herd level by testing quarter milk samples. The prevalence of MRSA was 4.8% (3/63; 95% confidence interval=0-10.2%) and 60% (33/55; 95% confidence interval=47.05-72.95) in farm A and B, respectively. In farm A, MRSA was also isolated from humans, pigs sampled at both farm and slaughterhouse level, and from environmental samples collected at the pig facilities. The dairy cattle facilities of farm A tested negative for MRSA. In farm B, MRSA was isolated from environmental dust samples in both the cattle and pig facilities, whereas nasal swabs collected from cows and from humans tested negative. Sixty-three selected MRSA isolates obtained from different sources in farm A and B were genetically characterized by multilocus sequence typing, spa-typing, ribosomal spacer-PCR, and also tested for the presence of specific virulence genes and for their phenotypical antimicrobial susceptibility by broth microdilution method. Different clonal complex (CC) and spa-types were identified, including CC398, CC97, and CC1, CC already reported in livestock animals in Italy. The MRSA isolates from quarter milk of farm A and B mostly belonged to CC97 and CC398, respectively. Both lineages were also identified in humans in farm A. The CC97 and CC398 quarter milk isolates were also identified as genotype GTBE and GTAF by ribosomal spacer-PCR respectively, belonging to distinct clusters with specific virulence and resistance patterns. The GTBE and GTAF clusters also included swine, environmental, and human isolates from both farms. A high heterogeneity in the genetic and phenotypic profiles was observed in environmental isolates, in particular from farm B. These results demonstrate the possibility of a dynamic sharing and exchange of MRSA lineages or genotypes between different species and farm compartments in mixed-species farms. The risk of transmission between swine and related dairy cattle herds should be considered. Our findings also confirm the zoonotic potential of livestock-associated MRSA and underline the importance of applying biosecurity measures and good hygiene practices to prevent MRSA spread at the farm level and throughout the food production chain.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Meticilina , Animales , Bovinos , Granjas , Femenino , Humanos , Ganado , Pruebas de Sensibilidad Microbiana , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/genética , Porcinos
4.
J Dairy Sci ; 99(10): 8250-8258, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27522416

RESUMEN

Mastitis due to intramammary infection is one of the most economically relevant diseases in dairy cows, causing reductions in milk quality and quantity. Currently, mastitis monitoring is based on somatic cell count (SCC) and bacteriologic culture (BC) of milk. Nevertheless, inflammation-specific protein markers might provide more sensitive and reliable assays, enabling immunoassay-based screening strategies. Cathelicidin is an inflammatory protein released in milk that has recently demonstrated fair reliability and diagnostic potential for ewe mastitis. To assess its performance in cows, 531 quarter milk samples from 2 herds were tested using cathelicidin ELISA, SCC, and BC. We found that 29.0% of samples were positive for cathelicidin, 18.8% had SCC >200,000 cells/mL, and 13.7% were BC-positive. Cathelicidin showed a strong positive correlation with SCC as demonstrated by receiver operating characteristics curve analysis and by the clustering of cathelicidin-negative and cathelicidin-positive samples in association with low and high SCC values, respectively. For evaluating the diagnostic performance of a novel test, BC cannot be considered a reliable gold standard for true disease status because of its known limitations. Therefore, we assessed the sensitivity (Se) and specificity (Sp) of the milk cathelicidin ELISA using a latent class analysis approach together with BC and SCC by considering different diagnostic thresholds to identify the preferred Se/Sp combination. We modeled conditional dependence of cathelicidin and SCC to account for their close association. The cathelicidin ELISA showed higher Se than SCC and BC for almost all threshold combinations. In fact, at the best-performing threshold combination, the Se of cathelicidin was 80.6%, 6.2 percentage points higher than that of SCC >200,000 cells/mL (74.4%) and similar to that of SCC >100,000 cells/mL (80.2%). Most importantly, this Se was obtained with a loss in Sp of only 1.4 percentage points compared with SCC >200,000 cells/mL (94.9% Sp for cathelicidin vs. 96.3% for SCC >200,000). The limited Se of BC (38.8%) was also confirmed in this study, and BC showed a slightly lower Sp than both cathelicidin and SCC for most of threshold combinations. This study confirmed that cathelicidin is released in the milk of cows with mastitis and that its presence is highly correlated with SCC. The measurement of cathelicidin by ELISA may hold significant potential for improving the sensitivity of mastitis detection in dairy cows while maintaining high specificity.


Asunto(s)
Mastitis Bovina/microbiología , Leche/microbiología , Animales , Bovinos , Recuento de Células/veterinaria , Femenino , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
5.
J Dairy Sci ; 99(8): 6519-6531, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27265178

RESUMEN

The study objective was to compare 2 commercial dry cow mastitis products at the quarter level, with concurrent internal teat sealant application, evaluating the cure risk difference, odds of a cure, odds of a new intramammary infection (NIMI) during the dry period, and risk for a clinical mastitis (CM) case between calving and 60d in milk (DIM). A total of 590 cows (2,360 quarters) from 8 commercial dairy herds in Italy were enrolled and randomized to 1 of the 2 treatments at dry off: Cefovet A (CF; 250mg of cephazoline; Merial Italia SpA, Milan, Italy), and Cepravin (CP; 250mg of cephalonium dehydrate MSD Animal Health Srl, Segrate, Italy). Quarter milk samples were collected before dry cow therapy treatment at dry off, 2 to 9 DIM, and 10 to 17 DIM. Quarter milk samples from CM cases were collected during the first 60 DIM. Noninferiority analysis was used to evaluate the effect of treatment on the risk difference of a bacteriological cure during the dry period, the primary outcome. The odds of cure, developing a NIMI during the dry period, and the risk of a CM event within 60 DIM were evaluated with multivariable logistic regression and hazard analysis, respectively. The overall crude quarter-level prevalence of NIMI at dry off was 15.3%. The most common pathogen isolated from milk samples at dry-off was coagulase-negative staphylococci. Noninferiority analysis showed no effect of treatment on the risk difference for a cure between dry off and both postpartum samples, difference was 0.013. The least squares means from the multivariable model evaluating the odds of cure was 94% for CF and 95%for CP. We observed no effect of treatment on the odds for the presence of a NIMI at 2 to 9 DIM (least squares means: CF=0.09 and CP=0.07), nor did we note a difference in risk of experiencing a CM event between calving and 60 DIM (hazard ratio=0.8). In conclusion, no difference was observed between the 2 products evaluated when assessing the aforementioned outcomes in quarters also receiving an internal teat sealant.


Asunto(s)
Lactancia , Mastitis Bovina/epidemiología , Animales , Antibacterianos/uso terapéutico , Bovinos , Cefalosporinas/uso terapéutico , Femenino , Glándulas Mamarias Animales/efectos de los fármacos , Leche/efectos de los fármacos
6.
J Dairy Sci ; 97(8): 5250-64, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24881797

RESUMEN

The aim of this study was to evaluate vaccine efficacy of a commercial vaccine (Startvac, Hipra Spain) aimed at reducing intramammary infections (IMI) with Staphylococcus aureus and coagulase-negative staphylococci under field conditions. During the 21-mo duration of the study, 1,156 lactations from 809 cows were enrolled in 2 herds. During the first phase of the trial, all cows that were due to calve were vaccinated until approximately 50% of cows in the milking herd were vaccinated (at ~6mo). At that point, when 50% vaccination coverage was reached, cows that were due to calve were randomly assigned to be vaccinated or left as negative controls. Cure rate, rate of new infection, prevalence, and duration of infections were analyzed. Vaccination resulted in a moderate reduction in incidence of new staphylococcal IMI and a more pronounced reduction in duration of IMI associated with reduction of the basic reproduction ratio of Staph. aureus by approximately 45% and of coagulase-negative staphylococci by approximately 35%. The utilization of vaccine in combination with other infection-control procedures, such as excellent milking procedures, treatment, segregation, and culling of known infected cattle, will result in an important reduction in incidence and duration of intramammary staphylococcal infections.


Asunto(s)
Vacunas Bacterianas/inmunología , Mastitis Bovina/epidemiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/inmunología , Vacunación/veterinaria , Animales , Vacunas Bacterianas/administración & dosificación , Bovinos , Coagulasa/metabolismo , Femenino , Incidencia , Mastitis Bovina/microbiología , Prevalencia , España/epidemiología , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Vacunación/normas
7.
J Dairy Sci ; 94(9): 4574-7, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21854930

RESUMEN

The present study was undertaken during an outbreak of clinical and subclinical mastitis in 14 dairy cows caused by Candida rugosa, in which high somatic cell counts were seen and cases did not respond to antibiotic treatment. Intramammary infection cured spontaneously in 10 cows, whereas 4 cows were culled as a result of persistent infections. Repeated sampling of these cows and biomolecular analysis of the isolates showed that the infections were caused by the same genotype, even over a period of 2 lactations. Random amplification of the genome of C. rugosa milk isolates gave 3 different DNA banding patterns (genotypes G1, G2, and G3). Viable cells of C. rugosa were also isolated from various environmental sources and were present in high concentrations in total mixed ration samples, which could be considered the primary source of diffusion of viable yeast cells in the environment, as demonstrated by genotyping. The proven capacity of these microorganisms to survive in the environment of the cow, such as the total mixed ration, bedding, water, and cow skin, and to cause persistent intramammary infections highlights the importance of mycotic spread in dairy herds.


Asunto(s)
Candida/genética , Candidiasis/veterinaria , Glándulas Mamarias Animales/microbiología , Mastitis Bovina/microbiología , Animales , Candidiasis/microbiología , Bovinos , Microbiología Ambiental , Femenino , Genotipo , Técnicas de Genotipaje/veterinaria , Mastitis Bovina/epidemiología , Leche/microbiología
8.
Clin Neurophysiol ; 120(1): 174-80, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19022703

RESUMEN

OBJECTIVE: To evaluate the after-effects of low frequency, sub-threshold repetitive Transcranial Magnetic Stimulation (rTMS) of primary motor cortex, on the excitability of Blink Reflex (BR) in healthy subjects. METHODS: The BR recovery cycle was carried out in 10 healthy volunteers in basal conditions, immediately after rTMS (30s), 15 and 60min later. A paired electric supraorbital stimulus paradigm with inter-stimulus intervals (ISI) of 100-600-1000-1500ms was used. The "real" rTMS consisted of a 200 stimuli long train delivered at 1Hz and intensity 80% of rest Motor Threshold of the FDI muscle, using a focal coil applied over the primary motor cortex region. The basal BR recovery cycle was also compared with that obtained after a "sham" rTMS. RESULTS: The recovery of the R2 component of the BR was significantly suppressed 30s after rTMS. This effect was also observed at 15min, though of lower magnitude and only at long ISIs (1000-1500ms). No significant effect on R2 recovery was observed 60min after real rTMS as well as after sham rTMS. CONCLUSIONS: rTMS of motor cortex modulates the excitability of BR through its action on cortical excitability and on the cortical facilitatory drive to the brainstem reflex pathways. SIGNIFICANCE: Slow (1Hz), sub-threshold rTMS of motor cortex determines a long-lasting reduction of excitability of BR.


Asunto(s)
Parpadeo/fisiología , Potenciales Evocados Motores/fisiología , Corteza Motora/fisiología , Estimulación Magnética Transcraneal , Adulto , Mapeo Encefálico , Estimulación Eléctrica/métodos , Electromiografía , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Músculo Esquelético/fisiología , Vías Nerviosas/fisiología , Tiempo de Reacción/fisiología , Adulto Joven
9.
Acta Neurol Scand ; 111(3): 199-201, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15691290

RESUMEN

Three Alzheimer's disease patients with Pisa syndrome were presented. These patients were treated with cholinesterase inhibitors within a post-marketing surveillance study. The clinical and pharmacological histories of these patients suggest a relation between cholinesterase inhibitors and the pleurothotonus. The diffuse use of cholinesterase inhibitors in the treatment of dementia may cause an increasing number of Pisa syndrome cases.


Asunto(s)
Enfermedad de Alzheimer/complicaciones , Distonía/etiología , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/epidemiología , Inhibidores de la Colinesterasa/efectos adversos , Distonía/inducido químicamente , Distonía/epidemiología , Femenino , Humanos , Incidencia , Síndrome
10.
J Med Chem ; 44(22): 3582-91, 2001 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-11606122

RESUMEN

In the search for a novel water-soluble general anesthetic agent the activity of an alpha-amino acid phenolic ester lead, identified from patent literature, was markedly improved. In addition to improving in vivo activity in mice, good in vitro activity at GABA(A) receptors was also conferred. Within the series of compounds good enantioselectivity for both in vitro and in vivo activity was found, supporting a protein-mediated mechanism of action for anesthesia involving allosteric modulation of GABA(A) receptors. alpha-Amino acid phenolic ester 19, as the hydrobromide salt Org 25435, was selected for clinical evaluation since it retained the best overall anesthetic profile coupled with improved stability and water solubility. In the clinic it proved to be an effective intravenous anesthetic in man with rapid onset of and recovery from anesthesia at doses of 3 and 4 mg/kg.


Asunto(s)
Aminoácidos/síntesis química , Anestésicos Generales/síntesis química , GABAérgicos/síntesis química , Fenoles/síntesis química , Receptores de GABA-A/efectos de los fármacos , Regulación Alostérica , Aminoácidos/química , Aminoácidos/farmacología , Anestésicos Generales/química , Anestésicos Generales/farmacología , Animales , Encéfalo/metabolismo , Cromatografía Líquida de Alta Presión , Evaluación Preclínica de Medicamentos , Ésteres , GABAérgicos/química , GABAérgicos/farmacología , Técnicas In Vitro , Masculino , Ratones , Modelos Moleculares , Oocitos/fisiología , Fenoles/química , Fenoles/farmacología , Ensayo de Unión Radioligante , Ratas , Ratas Wistar , Solubilidad , Relación Estructura-Actividad , Xenopus laevis
12.
J Dairy Sci ; 82(10): 2101-7, 1999 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-10531594

RESUMEN

A change in the epidemiology of mastitis in recent years has emphasized the role of the udder immune system in the pathogenesis of Staphylococcus aureus. Therefore, if the bovine or udder immune capability could be enhanced, susceptibility to Staph. aureus could be reduced and antibiotic efficacy could be increased. Immune system defense mechanisms could be enhanced by vaccination and by biological response modifiers. Within this latter group, a biological response modifier obtained from Parapox ovis that was attenuated over 200 tissue culture passages was recently developed and commercialized in some European countries. This study reports the results of a field trial on the efficacy of this biological response modifier in reducing Staph. aureus intramammary infection (IMI) after calving in primiparous and pluriparous cows. The trial included 106 cows sampled six times (55 cows from herd A and 51 from herd B) for a total of 2544 quarter milk samples. The analysis of IMI prevalence showed that 25.09% of samples were bacteriologically positive in the placebo group, and 23.17% of the positive samples were observed in the biological response modifier group. Staphylococcus aureus IMI had a frequency of 11.44% in the placebo group and 6.00% in the biological response modifier group. The dynamic of the hazards showed significantly lower rates in the biological response modifier group than in the placebo group (risk ratio = 0.47). Treatment with the parapox-containing biological response modifier showed significant reduction of Staph. aureus IMI around calving, and this reduction was attributed to an increase in immune defenses.


Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Factores Inmunológicos/uso terapéutico , Mastitis Bovina/prevención & control , Infecciones Estafilocócicas/prevención & control , Vacunas Virales/uso terapéutico , Adyuvantes Inmunológicos/administración & dosificación , Animales , Bovinos , Femenino , Mastitis Bovina/epidemiología , Mastitis Bovina/microbiología , Parapoxvirus/inmunología , Infecciones Estafilocócicas/epidemiología , Vacunas Virales/administración & dosificación
13.
Neuroscience ; 77(4): 1029-36, 1997 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9130784

RESUMEN

Dopamine neurons in midbrain coronal slices from adult rats (40-70 days old) discharged only in pacemaker-like mode. Irregular or bursting mode was never observed. In contrast, dopamine neurons in slices from immature rats (15-21 days old) exhibited not only pacemaker-like firing (53.4% of neurons), but also irregular and bursting patterns (28.3 and 18.3%, respectively). Glutamate and kainate increased the firing rate but failed to induce bursts in dopamine neurons from either adult or immature rats. N-Methyl-D-aspartate augmented the firing rate in all neurons from adult rats and produced a modest increase of bursts in only three out of 18 cells. In slices from immature rats, N-methyl-D-aspartate activated the discharge rate in all neurons and also induced bursts in 37 and 53% of pacemaker and irregular neurons, respectively, and increased the occurrence of spikes in bursts in 76% of spontaneously bursting neurons. The selective N-methyl-D-aspartate receptor antagonist (+/-)2-amino,5-phosphonopentanoic acid prevented N-methyl-D-aspartate-induced changes and also reduced spontaneous bursts, suggesting that bursting discharge is mediated by N-methyl-D-aspartate receptor activation. While pacemaker neurons from immature and from adult rats exhibited the same sensitivity to N-methyl-D-aspartate-induced stimulation of firing rate, spontaneously bursting neurons were more sensitive than pacemaker neurons from either immature or adult rats. The present study indicates that spontaneous bursting, dependent on N-methyl-D-aspartate receptor activation, is present, and may be induced, in dopamine neurons in slices from immature rats. Its absence from cells in slices from adult rats may reflect a reduced sensitivity of N-methyl-D-aspartate receptors on dopamine or the loss of the N-methyl-D-aspartate-activated burst generator.


Asunto(s)
Dopamina/fisiología , Mesencéfalo/citología , Neuronas/fisiología , Receptores de N-Metil-D-Aspartato/fisiología , 2-Amino-5-fosfonovalerato/farmacología , Factores de Edad , Animales , Animales Recién Nacidos , Electrofisiología , Agonistas de Aminoácidos Excitadores/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Ácido Glutámico/farmacología , Ácido Kaínico/farmacología , Masculino , Mesencéfalo/química , N-Metilaspartato/farmacología , Neuronas/química , Periodicidad , Ratas , Ratas Sprague-Dawley , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores
14.
Mol Pharmacol ; 51(3): 484-90, 1997 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-9058604

RESUMEN

The effects of subunit composition of the gamma-aminobutyric acid (GABA) type A receptor on the multiple actions of the general anesthetics alphaxalone and etomidate were investigated. The abilities of the two drugs to activate directly Cl- currents and to modulate GABA-evoked Cl- currents mediated by human recombinant GABA(A) receptors composed of alpha1, gamma2S, and either beta1, beta2, or beta3 subunit expressed in Xenopus laevis oocytes were compared. Both alphaxalone and etomidate evoked Cl currents in alpha1 beta1 gamma2S, alpha1 beta2 gamma2S, and alpha1 beta3 gamma2S receptors, an action that was blocked by both SR 95531 and picrotoxin. However, although maximal current activation by alphaxalone varied only slightly with the specific beta subunit isoform present, the efficacy of etomidate showed a rank order of beta3 > beta2 >>> beta1. In addition, beta1 homomeric receptors were markedly activated by etomidate but not by alphaxalone. Conversely, receptors consisting of alpha1 and gamma2S subunits were markedly activated by alphaxalone but not by etomidate. The modulatory effect of alphaxalone was also not markedly influenced by the beta-specific subunit isoform, whereas the modulatory efficacy of etomidate showed a rank order of beta3 > beta2 >> beta1. These results further demonstrate that the actions of general anesthetics at GABA(A) receptors are influenced by receptor subunit composition, and they suggest that the effects of alphaxalone and etomidate are mediated by different binding sites on the receptor complex.


Asunto(s)
Anestésicos/farmacología , Etomidato/farmacología , Pregnanodionas/farmacología , Receptores de GABA-A/química , Receptores de GABA-A/efectos de los fármacos , Animales , Sitios de Unión , Cloruros/metabolismo , Oocitos , Picrotoxina/farmacología , Piridazinas/farmacología , Receptores de GABA-A/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacología , Xenopus laevis
15.
Neuropharmacology ; 35(12): 1753-60, 1996.
Artículo en Inglés | MEDLINE | ID: mdl-9076754

RESUMEN

Loreclezole, an anticonvulsant and antiepileptic compound, potentiates gamma-aminobutyric acid (GABA) type A receptor function, by interacting with a specific allosteric modulatory site on receptor beta-subunits. A similar selectivity for GABAA receptor beta-subunits is apparent for the direct activation of receptor-operated Cl- channels, by the general anesthetics propofol and pentobarbital. The ability of loreclezole to activate GABAA receptors directly has now been compared, biochemically and electrophysiologically, with that of propofol. In well-washed rat cortical membranes (devoid of endogenous GABA), loreclezole and propofol increased t-[35S]butylbicyclophosphorothionate ([35S]TBPS) binding by up to 28% (at 5 microM) and 80% (at 10 microM), respectively. Higher concentrations (50-100 microM) of both compounds inhibited [35S]TBPS binding with great efficacy, an effect mimicked by GABA. In contrast, the benzodiazepine diazepam increased [35S]TBPS binding, but failed to inhibit this parameter, even at high concentrations. At concentrations of 50-100 microM, loreclezole induced inward Cl- currents in the absence of GABA, in Xenopus oocytes expressing human recombinant GABAA receptors, comprised of alpha 1-, beta 2- and gamma 2S-subunits. At 100 microM, the current evoked by loreclezole was 26% of that induced by 5 microM GABA. The current evoked by 100 microM propofol was 98% of that induced by 5 microM GABA. Currents induced by loreclezole, like those evoked by propofol, were potentiated by diazepam in a flumazenil-sensitive manner and blocked by either bicuculline or picrotoxin. These data suggest that loreclezole shares, with propofol, an agonistic action at GABAA receptors containing the beta 2-subunit and that the different efficacies of the two compounds in this regard, may underlie the difference in their pharmacological profiles. The failure of loreclezole to activate GABAA receptors containing the beta 1-subunit may be responsible for its lack of hypnotic effect.


Asunto(s)
Anticonvulsivantes/farmacología , Corteza Cerebral/metabolismo , Receptores de GABA-A/fisiología , Triazoles/farmacología , Animales , Bicuculina/farmacología , Unión Competitiva , Compuestos Bicíclicos Heterocíclicos con Puentes/metabolismo , Membrana Celular/metabolismo , Canales de Cloruro/efectos de los fármacos , Canales de Cloruro/fisiología , Convulsivantes/metabolismo , ADN Complementario , Diazepam/farmacología , Femenino , Humanos , Cinética , Sustancias Macromoleculares , Masculino , Potenciales de la Membrana/efectos de los fármacos , Oocitos/fisiología , Picrotoxina/farmacología , Propofol/farmacología , Ratas , Ratas Sprague-Dawley , Receptores de GABA-A/química , Receptores de GABA-A/efectos de los fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/efectos de los fármacos , Proteínas Recombinantes/metabolismo , Xenopus laevis , Ácido gamma-Aminobutírico/farmacología
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