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1.
Vet Sci ; 11(2)2024 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-38393098

RESUMEN

The neutrophil-to-lymphocyte ratio (NLR) can help in assessing inflammatory diseases, sepsis, and chronic hepatic conditions in humans. Dogs with congenital portosystemic shunts (PSSs) have signs of generalized inflammation, and the clinical signs can overlap with other conditions, including hypoadrenocorticism (HOC). Thus, the potential diagnostic and prognostic value of leukocyte ratios as surrogate markers was assessed in a retrospective case-control study including 106 dogs diagnosed with PSSs. The disease control groups were dogs with parenchymal hepatopathy (PH; n = 22) or HOC (n = 31). In the PSS dogs, the blood NLRs were associated with the severity of systemic inflammation but not with the shunt type, hepatoencephalopathy, systemic infection, or hypoglycemia. The baseline NLRs did not differ between the three disease groups, between medically and surgically treated PSS dogs, or between those with successful PSS ligation and dogs experiencing peri-/post-surgical complications. However, dogs requiring two consecutive surgical interventions had significantly higher NLRs, and an NLR of <2.53 distinguished dogs with successful shunt ligation in one surgery from those requiring two consecutive surgeries for PSS closure. The blood NLR might be a useful clinicopathologic variable in PSS, but its value in helping differentiate PSS from HOC cases appears low. Integrating the NLR into a diagnostic algorithm may allow for a prediction of the number of surgical interventions required.

2.
J Med Internet Res ; 25: e43883, 2023 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-37656499

RESUMEN

BACKGROUND: Providing informed consent means agreeing to participate in a clinical trial and having understood what is involved. Flawed informed consent processes, including missing dates and signatures, are common regulatory audit findings. Electronic consent (eConsent) uses digital technologies to enable the consenting process. It aims to improve participant comprehension and engagement with study information and to address data quality concerns. OBJECTIVE: This systematic literature review aimed to assess the effectiveness of eConsent in terms of patient comprehension, acceptability, usability, and study enrollment and retention rates, as well as the effects of eConsent on the time patients took to perform the consenting process ("cycle time") and on-site workload in comparison with traditional paper-based consenting. METHODS: The systematic review was conducted and reported in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Ovid Embase and Ovid MEDLINE were systematically searched for publications reporting original, comparative data on the effectiveness of eConsent in terms of patient comprehension, acceptability, usability, enrollment and retention rates, cycle time, and site workload. The methodological validity of the studies that compared outcomes for comprehension, acceptability, and usability across paper consent and eConsent was assessed. Study methodologies were categorized as having "high" validity if comprehensive assessments were performed using established instruments. RESULTS: Overall, 37 publications describing 35 studies (13,281 participants) were included. All studies comparing eConsenting and paper-based consenting for comprehension (20/35, 57% of the studies; 10 with "high" validity), acceptability (8/35, 23% of the studies; 1 with "high" validity), and usability (5/35, 14% of the studies; 1 with "high" validity) reported significantly better results with eConsent, better results but without significance testing, or no significant differences in overall results. None of the studies reported better results with paper than with eConsent. Among the "high" validity studies, 6 studies on comprehension reported significantly better understanding of at least some concepts, the study on acceptability reported statistically significant higher satisfaction scores, and the study on usability reported statistically significant higher usability scores with eConsent than with paper (P<.05 for all). Cycle times were increased with eConsent, potentially reflecting greater patient engagement with the content. Data on enrollment and retention were limited. Comparative data from site staff and other study researchers indicated the potential for reduced workload and lower administrative burden with eConsent. CONCLUSIONS: This systematic review showed that compared with patients using paper-based consenting, patients using eConsent had a better understanding of the clinical trial information, showed greater engagement with content, and rated the consenting process as more acceptable and usable. eConsent solutions thus have the potential to enhance understanding, acceptability, and usability of the consenting process while inherently being able to address data quality concerns, including those related to flawed consenting processes.


Asunto(s)
Exactitud de los Datos , Tecnología Digital , Humanos , Electrónica , Consentimiento Informado , Participación del Paciente
3.
Acta Ophthalmol ; 101(2): 123-139, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36117281

RESUMEN

Intravitreally injected anti-vascular endothelial growth factor (anti-VEGF) agents are first-line treatment for neovascular age-related macular degeneration (nAMD). Phase 3 trials demonstrated non-inferiority of anti-VEGF therapy with brolucizumab compared with aflibercept in best corrected visual acuity (BCVA) gains, with superior anatomical outcomes after brolucizumab. The purpose of the review was to summarize real-world efficacy and safety data on brolucizumab in patients with nAMD. The review protocol was registered with PROSPERO (ID: CRD42021290530). We conducted systematic searches in Embase, Medline and key ophthalmology congress websites (19 October 2021). Original reports of efficacy and/or safety in patients receiving brolucizumab to treat nAMD in clinical practice were eligible. The descriptive summary includes reports describing at least 10 brolucizumab-treated eyes. In total, 2907 brolucizumab-treated eyes from 26 studies were included. Outcomes were available for treatment-naive eyes (six studies), eyes switched to brolucizumab from other anti-VEGFs (16 studies), and/or treatment-naive and switch eyes combined (eight studies). Follow-up time points ranged from 4 weeks to 1 year post-brolucizumab initiation. For BCVA, significant improvements compared with brolucizumab initiation were reported in four of six studies in treatment-naive eyes (mean BCVA improvement, range: +3.7 to +11.9 Early Treatment Diabetic Retinopathy Study [ETDRS] letters) and in three of 12 studies in switch eyes (range: +9.0 to +15 ETDRS letters) (all p < 0.05); remaining studies reported no significant post-brolucizumab BCVA changes. For central subfield thickness (CST), improvements post-brolucizumab initiation were reported in all six studies in treatment-naive eyes (mean CST improvement, range: -113.4 to -150.1 µm) and in eight of 11 studies in switch eyes (range: -26 to -185.7 µm) (all p < 0.05). The 14 studies reporting on intraretinal, subretinal and/or total fluid observed improvements post-brolucizumab initiation. The four studies comparing treatment intervals observed extension of the interval between injections after switching to brolucizumab from other anti-VEGFs. Incidence of intraocular inflammation ranged from 0% to 19%. In conclusion, real-world efficacy and safety data concur with brolucizumab pivotal trials. Additionally, reduction of disease activity in anti-VEGF switch eyes was demonstrated by fluid reduction and/or visual acuity gain, along with prolongation of the interval between injections.


Asunto(s)
Retinopatía Diabética , Degeneración Macular , Degeneración Macular Húmeda , Humanos , Ranibizumab/uso terapéutico , Inhibidores de la Angiogénesis/uso terapéutico , Factor A de Crecimiento Endotelial Vascular , Inyecciones Intravítreas , Degeneración Macular/tratamiento farmacológico , Receptores de Factores de Crecimiento Endotelial Vascular/uso terapéutico , Retinopatía Diabética/tratamiento farmacológico , Proteínas Recombinantes de Fusión/uso terapéutico , Degeneración Macular Húmeda/diagnóstico , Degeneración Macular Húmeda/tratamiento farmacológico
4.
Top Companion Anim Med ; 46: 100597, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34710633

RESUMEN

Inflammatory bowel diseases (IBD) in humans are associated with electrolyte shifts and diarrhea. Chronic inflammatory enteropathies (CIE) in dogs produce inflammatory lesions usually located more diffusely throughout the gastrointestinal tract. The prevalence of electrolyte imbalances in canine CIE is unknown. We retrospectively evaluated serum electrolyte (Na+, Cl-, corrected Cl-, and K+) concentrations in 37 dogs with CIE. Hypokalemia was the most frequent electrolyte abnormality, affecting 7 (19%) CIE dogs and with no difference between food-responsive and immunosuppressant-responsive (IRE) cases. Hyponatremia was less common (14%) and predominantly seen with IRE; serum Na+ concentration correlated with the severity of diarrhea and duodenal histologic lesions. Hypo- (5%) and hyperchloridemia (11%) were also detected. Electrolyte imbalances occur with equal frequency in canine CIE and human IBD. Increased K+ secretion might exceed compromised Na+/Cl- absorption or K+ shifts might be more pronounced in canine CIE. Therefore, the mechanisms underlying CIE-associated diarrhea warrant further research.


Asunto(s)
Enfermedades de los Perros , Enfermedades Inflamatorias del Intestino , Animales , Diarrea/veterinaria , Perros , Electrólitos , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/veterinaria , Estudios Retrospectivos
5.
J Vet Diagn Invest ; 33(3): 516-527, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33554784

RESUMEN

Few routinely available biomarkers are clinically useful in assessing dogs with chronic enteropathy (CE) and aid in CE subclassification. The diagnostic potential of the blood neutrophil-to-lymphocyte ratio (NLR) has not been evaluated in canine CE. We evaluated the NLR in 93 dogs with CE (no steroid treatment for ≥2 wk prior) and tested for an association with clinical, clinicopathologic, and histologic characteristics and also with CE subclassification. NLR was significantly higher in CE dogs with severe clinical disease than dogs with mild clinical disease (p = 0.047). Hypoalbuminemia (p < 0.001), but not hypocobalaminemia, was associated with higher NLRs. NLR was correlated with fecal alpha1-proteinase inhibitor concentrations (ρ = 0.47) and the serum-to-fecal alpha1-proteinase inhibitor ratio (ρ = -0.48; both p < 0.001) but not with serum or fecal inflammatory markers nor with the overall histologic score (all p > 0.05). Dogs with steroid- or other immunosuppressant-responsive (IRE) or nonresponsive enteropathy (NRE) had significantly higher NLRs (median: 7.3) than dogs with food-responsive enteropathy (FRE; median: 3.0; p = 0.003), and a NLR ≥5.5 best distinguished both groups of dogs. No difference in NLR was detected between dogs with IRE and dogs diagnosed with NRE. These findings suggest that leukogram changes (i.e., NLR) could be clinically useful in canine CE, and that neutrophils might play a role in the systemic inflammatory response associated with canine CE. The NLR can be easily assessed on routine hematology and can potentially aid in the subclassification of dogs with CE based on the response to treatment.


Asunto(s)
Enfermedades de los Perros/diagnóstico , Pruebas Hematológicas/veterinaria , Enfermedades Inflamatorias del Intestino/veterinaria , Linfocitos/metabolismo , Neutrófilos/metabolismo , Animales , Biomarcadores/sangre , Perros , Heces/química , Femenino , Enfermedades Inflamatorias del Intestino/diagnóstico , Masculino
6.
Eur Heart J Acute Cardiovasc Care ; 6(6): 522-531, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27142175

RESUMEN

AIMS: The aim of this systematic literature review was to assess the consequences of dual antiplatelet therapy discontinuation on clinical outcomes after acute coronary syndromes. METHODS AND RESULTS: A systematic literature search was conducted in PubMed to identify studies reporting data on patients who discontinued dual antiplatelet therapy (planned or unplanned) following acute coronary syndromes and on the clinical impact of dual antiplatelet therapy discontinuation. To be included, more than 50% of the study population had to have had acute coronary syndrome as their index event or, if less than 50%, outcomes data must have been reported separately for the group with acute coronary syndromes. Thirty publications covering 29 studies were identified for inclusion. There was much heterogeneity across studies regarding the included patient populations, treatment durations and outcome definitions and ascertainments. Dual antiplatelet therapy discontinuation was most commonly based on physician decision. Twenty-six studies reported that clopidogrel was prescribed as part of dual antiplatelet therapy. Dual antiplatelet therapy duration was positively associated with a lower risk of all-cause mortality (seven/eight studies), cardiovascular mortality (two/two studies), non-fatal myocardial infarction (two/three studies) and stent thrombosis (five/five studies) in patients and/or patient subgroups in studies without randomised treatment designs, although such associations were not observed in the one study that randomly assigned patients to treatment (i.e. planned discontinuation). CONCLUSIONS: Results from our systematic literature review generally support the benefit of longer-term dual antiplatelet therapy after acute coronary syndromes; however, further research is needed to determine the optimal length of dual antiplatelet therapy in patients after acute coronary syndrome, ideally using prospective studies.


Asunto(s)
Síndrome Coronario Agudo/tratamiento farmacológico , Aspirina/uso terapéutico , Ticlopidina/análogos & derivados , Privación de Tratamiento , Clopidogrel , Quimioterapia Combinada , Humanos , Inhibidores de Agregación Plaquetaria/uso terapéutico , Pronóstico , Ticlopidina/uso terapéutico , Factores de Tiempo
8.
Eur J Gastroenterol Hepatol ; 25(1): 2-14, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23202695

RESUMEN

Gastroesophageal reflux disease (GERD) symptoms are best assessed using patient-reported outcome (PRO) instruments. Guidance on developing well-defined and reliable instruments that capture optimal information from the patient's perspective was recently published by the US Food and Drug Administration and the European Medicines Agency. The aim of this systematic review was to identify and evaluate existing PRO instruments for GERD symptoms with regard to regulatory requirements. Systematic literature searches were conducted in PubMed and Embase to identify PRO instruments for GERD symptoms that have undergone psychometric evaluation. Content, construct and test-retest reliability, internal consistency, and responsiveness were evaluated in relation to regulatory recommendations. Supplementary searches were conducted to assess whether identified instruments had been used as clinical trial endpoint measures. The systematic literature searches identified 15 PRO instruments for GERD symptoms that have undergone psychometric evaluation. Eight were designed to evaluate GERD symptoms, two were to diagnose GERD, four were designed for both evaluative and diagnostic purposes, and one was designed for screening purposes. Five instruments were developed and reported to include most steps recommended by the Food and Drug Administration and European Medicines Agency, and have also been used as endpoint measures in clinical trials: the GERD Symptom Assessment Scale, the Nocturnal Gastro-oesophageal Reflux Disease Symptom Severity and Impact Questionnaire, the Reflux Questionnaire, the Reflux Disease Questionnaire, and the Proton pump inhibitor Acid Suppression Symptom test. Existing PRO instruments for GERD do not meet all the regulatory requirements for an outcome instrument in reflux trials and may need further validation.


Asunto(s)
Reflujo Gastroesofágico/diagnóstico , Pacientes , Encuestas y Cuestionarios , Determinación de Punto Final , Reflujo Gastroesofágico/complicaciones , Reflujo Gastroesofágico/terapia , Pirosis/diagnóstico , Pirosis/etiología , Humanos , Guías de Práctica Clínica como Asunto , Valor Predictivo de las Pruebas , Psicometría , Reproducibilidad de los Resultados , Autoinforme , Índice de Severidad de la Enfermedad , Encuestas y Cuestionarios/normas , Resultado del Tratamiento
9.
Clin Gastroenterol Hepatol ; 10(8): 863-873.e3, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22401904

RESUMEN

BACKGROUND & AIMS: This systematic review assesses findings of endoscopic surveys in the general population with regard to gastroesophageal reflux disease (GERD). METHODS: Systematic searches were conducted in PubMed and EMBASE. Authors were contacted for additional, unpublished data. RESULTS: Data on 61,281 individuals were included from 3 general population studies (Kalixanda study [Sweden], Loiano-Monghidoro study [Italy], SILC study [China]) and 8 health-check studies (Japan, n = 1; China, n = 1; Taiwan, n = 4; Korea, n = 2). The prevalence of reflux esophagitis was 15.5% (Kalixanda), 11.8% (Loiano-Monghidoro), and 6.4% (SILC); it ranged from 3.4% to 8.5% in health-check studies in Japan, China, and Korea (n = 4), but was higher (mean, 15.6%; range, 9.0%-24.6%; n = 4) in Taiwan. Hiatus hernia prevalence was 23.9% (Kalixanda), 43.0% (Loiano-Monghidoro), and 0.7% (SILC), and 0.8%-19.5% in health-check studies (n = 7). For endoscopically suspected esophageal metaplasia (ESEM), the prevalence was 10.3% (Kalixanda), 3.6% (Loiano-Monghidoro), and 1.8% (SILC), and 0.0%-3.4% in health-check studies (n = 4). The prevalence of reflux esophagitis among individuals without symptom-defined GERD was 12.1% (Kalixanda), 8.6% (Loiano-Monghidoro), 6.1% (SILC), and 1.6%-22.8% (health-check studies; n = 6). For individuals without symptom-defined GERD, the prevalence of ESEM was 9.4% (Kalixanda), 2.8% (Loiano-Monghidoro), and 1.8% (SILC). CONCLUSIONS: The prevalence of reflux esophagitis is higher in Sweden and Italy than in China, Korea, and Japan, but is within the range reported in Taiwan. Hiatus hernia and ESEM are generally more prevalent in Europe than in Asia. A considerable proportion of individuals without symptom-defined GERD has reflux esophagitis or ESEM.


Asunto(s)
Esofagoscopía/métodos , Esófago/patología , Reflujo Gastroesofágico/epidemiología , Reflujo Gastroesofágico/patología , Humanos
10.
Resuscitation ; 79(1): 125-32, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18556110

RESUMEN

AIM: The importance of ventilatory support during cardiac arrest and basic life support is controversial. This experimental study used dynamic computed tomography (CT) to assess the effects of chest compressions only during cardiopulmonary resuscitation (CCO-CPR) on alveolar recruitment and haemodynamic parameters in porcine model of ventricular fibrillation. MATERIALS AND METHODS: Twelve anaesthetized pigs (26+/-1 kg) were randomly assigned to one of the following groups: (1) intermittent positive pressure ventilation (IPPV) both during basic life support and advanced cardiac life support, or (2) CCO during basic life support and IPPV during advanced cardiac life support. Measurements were acquired at baseline prior to cardiac arrest, during basic life support, during advanced life support, and after return of spontaneous circulation (ROSC), as follows: dynamic CT series, arterial and central venous pressures, blood gases, and regional organ blood flow. The ventilated and atelectatic lung area was quantified from dynamic CT images. Differences between groups were analyzed using the Kruskal-Wallis test, and a p<0.05 was considered statistically significant. RESULTS: IPPV was associated with cyclic alveolar recruitment and de-recruitment. Compared with controls, the CCO-CPR group had a significantly larger mean fractional area of atelectasis (p=0.009), and significantly lower PaO2 (p=0.002) and mean arterial pressure (p=0.023). The increase in mean atelectatic lung area observed during basic life support in the CCO-CPR group remained clinically relevant throughout the subsequent advanced cardiac life support period and following ROSC, and was associated with prolonged impaired haemodynamics. No inter-group differences in myocardial and cerebral blood flow were observed. CONCLUSION: A lack of ventilation during basic life support is associated with excessive atelectasis, arterial hypoxaemia and compromised CPR haemodynamics. Moreover, these detrimental effects remain evident even after restoration of IPPV.


Asunto(s)
Masaje Cardíaco/métodos , Alveolos Pulmonares/fisiopatología , Atelectasia Pulmonar/fisiopatología , Fibrilación Ventricular/terapia , Animales , Análisis de los Gases de la Sangre , Modelos Animales de Enfermedad , Hemodinámica , Cuidados para Prolongación de la Vida , Microesferas , Alveolos Pulmonares/diagnóstico por imagen , Atelectasia Pulmonar/diagnóstico por imagen , Intercambio Gaseoso Pulmonar , Flujo Sanguíneo Regional , Porcinos , Tomografía Computarizada por Rayos X , Fibrilación Ventricular/fisiopatología
11.
Scand J Gastroenterol ; 43(6): 645-53, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18569980

RESUMEN

OBJECTIVE: The mortality associated with malignant complications of gastroesophageal reflux disease (GERD) is well recognized. The aim of this systematic review was to assess the less well-examined mortality associated with GERD and its non-malignant complications, including esophageal erosions, ulcers, bleeding, perforation and strictures. MATERIAL AND METHODS: Studies reporting mortality in GERD and its non-malignant complications were identified via systematic PubMed searches, and previously unpublished population mortality statistics from public access databases. RESULTS. Three countries were examined (USA, UK, Finland). Cohort studies (n=3) in the UK showed a 1.16- to 1.6-fold increase in risk of death in individuals with GERD compared with the general population, the majority of deaths being due to cardiac disease. Population data indicate that GERD and its likely esophageal complications were the cause of death in 685 and 521 cases, respectively, in the USA (year: 2003) (age-adjusted mortality: 2.3/million and 1.8/million, respectively), and in 36 and 349 cases, respectively, in England and Wales (2004) (0.6/million and 5.4/million, respectively). In Finland (2000), GERD-related mortality was 4.6/million. Mortality from GERD and its likely esophageal complications increased with age, and was between 1.2-fold and 1.8-fold higher in men than in women. Cohort studies in the USA are inconsistent on mortality risk associated with surgical therapy. Time-trend data suggest that mortality from GERD and its non-malignant complications has been increasing. CONCLUSIONS: Data from Europe and the USA show that GERD and its non-malignant complications can on rare occasions cause death.


Asunto(s)
Enfermedades del Esófago/etiología , Enfermedades del Esófago/mortalidad , Reflujo Gastroesofágico/mortalidad , Finlandia/epidemiología , Reflujo Gastroesofágico/complicaciones , Reflujo Gastroesofágico/terapia , Humanos , Factores de Riesgo , Reino Unido/epidemiología , Estados Unidos/epidemiología
12.
Eur J Cell Biol ; 84(4): 467-75, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15900706

RESUMEN

Synaptophysin and synaptobrevin are abundant membrane proteins of neuronal small synaptic vesicles. In mature, differentiated neurons they form the synaptophysin/synaptobrevin (Syp/Syb) complex. Synaptobrevin also interacts with the plasma membrane-associated proteins syntaxin and SNAP25, thereby forming the SNARE complex necessary for exocytotic membrane fusion. The two complexes are mutually exclusive. Synaptobrevin is a C-terminally membrane-anchored protein with one transmembrane domain. While its interaction with its SNARE partners is mediated exclusively by its N-terminal cytosolic region it has been unclear so far how binding to synaptophysin is accomplished. Here, we show that synaptobrevin can be cleaved in its synaptophysin-bound form by tetanus toxin and botulinum neurotoxin B, or by botulinum neurotoxin D, leaving shorter or longer C-terminal peptide chains bound to synaptophysin, respectively. A recombinant, C-terminally His-tagged synaptobrevin fragment bound to nickel beads specifically bound synaptophysin, syntaxin and SNAP25 from vesicular detergent extracts. After cleavage by tetanus toxin or botulinum toxin D light chain, the remaining C-terminal fragment no longer interacted with syntaxin or SNAP 25. In contrast, synaptophysin was still able to bind to the residual C-terminal synaptobrevin cleavage product. In addition, the His-tagged C-terminal synaptobrevin peptide 68-116 was also able to bind synaptophysin in detergent extracts from adult brain membranes. These data suggest that synaptophysin interacts with the C-terminal transmembrane part of synaptobrevin, thereby allowing the N-terminal cytosolic chain to interact freely with the plasma membrane-associated SNARE proteins. Thus, by binding synaptobrevin, synaptophysin may positively modulate neurotransmission.


Asunto(s)
Proteínas de la Membrana/metabolismo , Vesículas Sinápticas/metabolismo , Sinaptofisina/metabolismo , Animales , Toxinas Botulínicas/química , Histidina/química , Técnicas In Vitro , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Terminaciones Nerviosas/metabolismo , Terminaciones Nerviosas/ultraestructura , Proteínas del Tejido Nervioso/metabolismo , Fragmentos de Péptidos/química , Unión Proteica , Proteínas Qa-SNARE , Proteínas R-SNARE , Ratas , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Sinaptofisina/química , Proteína 25 Asociada a Sinaptosomas , Toxina Tetánica/química
13.
Biochem Soc Symp ; (72): 151-64, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15649139

RESUMEN

GPCRs (G-protein-coupled receptors) play key roles in many cellular processes, and malfunction may lead to a range of pathologies, including psychiatric and neurological disorders. It is therefore not surprising that this group of receptors supplies a majority of the targets for pharmaceutical drug development. Despite their importance, the mechanisms that regulate their function and signalling still remain only partially understood. Recently, it has become evident that a subset of GPCRs is not homogeneously distributed in the plasma membrane, but localizes instead to specific membrane microdomains known as lipid rafts. Lipid rafts are characterized by their enrichment in cholesterol and sphingolipids, and have been suggested to serve as platforms for a range of cellular signalling complexes. In the present review, we will be discussing the effects of the lipid raft environment on trafficking, signalling and internalization of raft-associated GPCRs.


Asunto(s)
Microdominios de Membrana/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animales , Transporte Biológico Activo , Humanos , Microdominios de Membrana/química , Modelos Moleculares , Estructura Molecular , Receptor de Adenosina A1/metabolismo , Receptor de Angiotensina Tipo 1/metabolismo , Receptores Adrenérgicos beta/metabolismo , Receptores de Bradiquinina/metabolismo , Receptores CCR5/metabolismo , Receptores Acoplados a Proteínas G/química , Receptores LHRH/metabolismo , Transducción de Señal
14.
Biochem Biophys Res Commun ; 321(4): 981-7, 2004 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-15358124

RESUMEN

Lipid raft domains have attracted much recent attention as platforms for plasma membrane signalling complexes. In particular, evidence is emerging that shows them to be key regulators of G protein coupled receptor function. The G protein coupled gamma-aminobutyric acid receptor B (GABA(B) receptor) co-isolates with lipid raft domains from rat brain cerebellum. In the present study, we show that the GABA(B1a,2) receptor was also present in lipid raft domains when expressed ectopically in a Chinese hamster ovary cell line. Lipid raft-associated receptor was functionally active, displaying a concentration-dependent increase in GTPgammaS binding in response to the receptor agonist GABA. Compared with whole cell membranes, lipid raft-associated receptor displayed an increased EC(50) and a reduced magnitude of response to GABA. We conclude that lipid raft association is an intrinsic property of the GABA(B1a,2) receptor and is not cell-type specific. In addition, localisation to lipid raft domains may provide a mechanism to inhibit receptor function.


Asunto(s)
Receptores de GABA-B/genética , Receptores de GABA-B/metabolismo , Animales , Células CHO , Cerebelo/metabolismo , Cricetinae , Regulación hacia Abajo , Agonistas de Receptores GABA-B , Expresión Génica , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Inmunohistoquímica , Microdominios de Membrana/metabolismo , Ratas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
15.
J Neurochem ; 90(1): 1-8, 2004 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15198661

RESUMEN

Synaptophysin is one of the most abundant membrane proteins of small synaptic vesicles. In mature nerve terminals it forms a complex with the vesicular membrane protein synaptobrevin, which appears to modulate synaptobrevin's interaction with the plasma membrane-associated proteins syntaxin and SNAP25 to form the SNARE complex as a prerequisite for membrane fusion. Here we show that synaptobrevin is preferentially cleaved by tetanus toxin while bound to synaptophysin or when existing as a homodimer. The synaptophysin/synaptobrevin complex is, however, not affected when neuronal secretion is blocked by botulinum A toxin which cleaves SNAP25. Excessive stimulation with alpha-latrotoxin or Ca(2+)-ionophores dissociates the synaptophysin/synaptobrevin complex and increases the interaction of the other SNARE proteins. The stimulation-induced dissociation of the synaptophysin/synaptobrevin complex is not inhibited by pre-incubating neurones with botulinum A toxin, but depends on extracellular calcium. However, the synaptophysin/synaptobrevin complex cannot be directly dissociated by calcium alone or in combination with magnesium. The dissociation of synaptobrevin from synaptophysin appears to precede its interaction with the other SNARE proteins and does not depend on the final fusion event. This finding further supports the modulatory role the synaptophysin/synaptobrevin complex may play in mature neurones.


Asunto(s)
Exocitosis/fisiología , Proteínas de la Membrana/metabolismo , Neuronas/metabolismo , Sinaptofisina/metabolismo , Animales , Toxinas Botulínicas Tipo A/farmacología , Química Encefálica , Calcio/metabolismo , Células Cultivadas , Dimerización , Exocitosis/efectos de los fármacos , Hipocampo/citología , Ionóforos/farmacología , Sustancias Macromoleculares , Magnesio/farmacología , Proteínas de la Membrana/química , Proteínas de la Membrana/efectos de los fármacos , Ratones , Proteínas del Tejido Nervioso/efectos de los fármacos , Proteínas del Tejido Nervioso/metabolismo , Neuronas/citología , Neuronas/efectos de los fármacos , Unión Proteica/efectos de los fármacos , Proteínas R-SNARE , Ratas , Venenos de Araña/farmacología , Estimulación Química , Sinaptofisina/química , Proteína 25 Asociada a Sinaptosomas , Sinaptosomas/química , Sinaptosomas/efectos de los fármacos , Toxina Tetánica/química , Toxina Tetánica/farmacología
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