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1.
QJM ; 112(12): 891-899, 2019 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-31350560

RESUMEN

BACKGROUND: Acute stroke is the third leading cause of death in Taiwan. Although statin therapy is widely recommended for stroke prevention, little is known about the epidemiology of statin therapy after acute ischemic stroke (AIS) in Taiwan. To investigate the effects of statin therapy on recurrent stroke, intracranial hemorrhage (ICH), coronary artery disease (CAD), cost of hospitalization and mortality, we conducted a nationwide population-based epidemiologic study. METHODS: Cases of AIS were identified from the annual hospitalization discharge diagnoses of the National Health Insurance Research Database with the corresponding International Classification of Diseases, ninth revision codes from January 2001 to December 2010. We divided the AIS patients into three groups: non-statin, pre-stroke statin and post-stroke statin. RESULTS: A total of 422 671 patients with AIS (including 365 419 cases in the non-statin group, 22 716 cases in the pre-stroke statin group and 34 536 cases in the post-stroke statin group) were identified. When compared to the non-statin group, both statin groups had a lower recurrent stroke risk [pre-stroke statin: odds ratio (OR) = 0.84; 95% confidence interval (CI) = 0.82-0.87; P < 0.0001; post-stroke statin: OR = 0.89; 95% CI = 0.86-0.91; P < 0.0001], lower ICH risk (pre-statin: OR = 0.75; 95% CI = 0.69-0.82; P < 0.0001; post-stroke statin: OR = 0.75; 95% CI = 0.71-0.81; P < 0.0001), and a lower mortality rate (pre-stroke statin: OR = 0.56; 95% CI = 0.53-0.59; P < 0.0001; post-stroke statin: OR = 0.51; 95% CI = 0.48-0.53; P < 0.0001). In terms of CAD, only the post-statin group had a lower risk (OR = 0.81; 95% CI = 0.79-0.84; P < 0.0001) than the non-statin group. The post-statin group had the lowest 1-year medical costs after index discharge among the three groups. CONCLUSIONS: Statin therapy reduced the risks of recurrent stroke, CAD, ICH and the first year mortality in patients after AIS. Treatment with statin therapy after AIS is a cost-effective strategy in Taiwan.


Asunto(s)
Isquemia Encefálica/tratamiento farmacológico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Accidente Cerebrovascular/tratamiento farmacológico , Anciano , Enfermedad de la Arteria Coronaria/epidemiología , Enfermedad de la Arteria Coronaria/etiología , Bases de Datos Factuales , Estudios Epidemiológicos , Femenino , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Hemorragias Intracraneales/inducido químicamente , Hemorragias Intracraneales/epidemiología , Masculino , Persona de Mediana Edad , Alta del Paciente/estadística & datos numéricos , Recurrencia , Factores de Riesgo , Accidente Cerebrovascular/mortalidad , Accidente Cerebrovascular/prevención & control , Taiwán/epidemiología , Factores de Tiempo , Resultado del Tratamiento
2.
Oncogene ; 36(41): 5770, 2017 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-28825723

RESUMEN

This corrects the article DOI: 10.1038/onc.2015.168.

3.
QJM ; 110(9): 565-570, 2017 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-28383687

RESUMEN

BACKGROUND: Caregivers play a major role in providing care for patients with Alzheimer's disease (AD) and are themselves at higher risk of health comorbidities. AIM: To address the impact of neuropsychiatric symptoms of patients in different stages of AD on their caregivers' burden. DESIGN: This prospective study enrolled 260 AD patients with clinical dementia rating (CDR) of 0.5, 1 and 2 at a tertiary medical center. METHODS: All patients were tested using the mini-mental state examination (MMSE), the cognitive abilities screening instrument (CASI), the neuropsychiatric inventory (NPI) and the CDR scale. Data regarding therapeutic outcomes of anti-Alzheimer's drugs were also collected. Caregivers were tested using NPI. RESULTS: The mean follow-up interval was 25.0 ± 12.2 months, and two patients died during follow-up. NPI-burden was positively correlated with NPI-sum ( r = 0.822, P < 0.001) but negatively correlated with years of education ( r = -0.140, P = 0.024), CASI score ( r = -0.259, P < 0.001) and MMSE score ( r = -0.262, P <0.001). Multiple linear regression analysis showed that only NPI-sum was independently associated with mean NPI-burden. Both higher mean CASI and MMSE scores had better therapeutic outcome of anti-Alzheimer's drugs ( P = 0.001 and P = 0.005, respectively). CONCLUSIONS: The severity of neuropsychiatric symptoms in patients with AD was positively associated with caregiver's stress, and patients with better cognitive functions, under treatment with anti-Alzheimer's drugs, had better therapeutic outcomes. To reduce the impact of neuropsychiatric symptoms, it is crucial to detect dementia in its early phases and provide early intervention with anti-Alzheimer's drugs, which might help decrease the caregiver burden, thereby improving their quality of life.


Asunto(s)
Enfermedad de Alzheimer , Síntomas Conductuales , Cuidadores/psicología , Costo de Enfermedad , Nootrópicos/uso terapéutico , Calidad de Vida , Adaptación Psicológica , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/psicología , Enfermedad de Alzheimer/terapia , Síntomas Conductuales/diagnóstico , Síntomas Conductuales/etiología , Síntomas Conductuales/terapia , China , Cognición , Femenino , Humanos , Masculino , Competencia Mental/psicología , Persona de Mediana Edad , Pruebas Neuropsicológicas , Estudios Prospectivos , Escalas de Valoración Psiquiátrica , Resultado del Tratamiento
4.
Oncogene ; 35(9): 1134-42, 2016 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-25982274

RESUMEN

MicroRNAs (miRNAs) are small RNAs that suppress gene expression by their interaction with 3'untranslated region of specific target mRNAs. Although the dysregulation of miRNAs has been identified in human cancer, only a few of these miRNAs have been functionally documented in breast cancer. Thus, defining the important miRNA and functional target involved in chemoresistance is an urgent need for human breast cancer treatment. In this study, we, for the first time, identified a key role of miRNA 520h (miR-520h) in drug resistance. Through protecting cells from paclitaxel-induced apoptosis, expression of miR-520h promoted the drug resistance of human breast cancer cells. Bioinformatics prediction, compensatory mutation and functional validation further confirmed the essential role of miR-520h-suppressed Death-associated protein kinase 2 (DAPK2) expression, as restoring DAPK2 abolished miR-520h-promoted drug resistance, and knockdown of DAPK2 mitigated cell death caused by the depletion of miR-520h. Furthermore, we observed that higher level of miR-520h is associated with poor prognosis and lymph node metastasis in human breast cancer patients. These results show that miR-520h is not only an independent prognostic factor, but is also a potential functional target for future applications in cancer therapeutics.


Asunto(s)
Neoplasias de la Mama/genética , Proteínas Quinasas Asociadas a Muerte Celular/biosíntesis , Resistencia a Antineoplásicos/genética , MicroARNs/biosíntesis , Apoptosis/efectos de los fármacos , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Línea Celular Tumoral , Proteínas Quinasas Asociadas a Muerte Celular/genética , Progresión de la Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , MicroARNs/genética , Paclitaxel/administración & dosificación , ARN Mensajero/biosíntesis
5.
Clin Microbiol Infect ; 17(4): 615-20, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20491832

RESUMEN

Although treatment of brain abscess requires a combination of antimicrobials and surgical intervention for the infected foci, nonsurgical, empirical treatment is possible and efficient in selected groups of patients. A total of 31 patients were enrolled in this 22-year retrospective study. We describe our therapeutic experiences and attempt to analyze the risk factors that were predictive of therapeutic outcomes. Multiple logistic regression was used to evaluate the relationships between baseline clinical factors and therapeutic outcome during the study period. Of these 31 patients, 25 had community-acquired infections, whereas the other six had nosocomially-acquired infections. Thirteen cases (42%) had a single brain abscess and the other 18 cases (58%) had multiple brain abscesses. Furthermore, the association of bacterial meningitis and brain abscess was found in 81% (25/31) of cases. The overall case fatality rate was 48% (15/31). Significant risk factors for poor outcomes included Glasgow coma scale (GCS) at presentation, presence of septic shock and neck stiffness. In addition, each reduction of one point on the GCS increased the poor outcome rate by 28%. The findings of the study demonstrate that both a higher mortality rate (48%) and worse outcomes were found in this select group of patients. Among the significant prognostic factors, a lower mean GCS at presentation was a major determinant of poor outcome.


Asunto(s)
Antibacterianos/administración & dosificación , Infecciones Bacterianas/tratamiento farmacológico , Absceso Encefálico/tratamiento farmacológico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Resultado del Tratamiento , Adulto Joven
6.
J Biomech Eng ; 127(4): 611-8, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16121531

RESUMEN

The fluid flow through a stenosed artery and its bypass graft in an anastomosis can substantially influence the outcome of bypass surgery. To help improve our understanding of this and related issues, the steady Navier-Stokes flows are computed in an idealized arterial bypass system with partially occluded host artery. Both the residual flow issued from the stenosis--which is potentially important at an earlier stage after grafting--and the complex flow structure induced by the bypass graft are investigated. Seven geometric models, including symmetric and asymmetric stenoses in the host artery, and two major aspects of the bypass system, namely, the effects of area reduction and stenosis asymmetry, are considered. By analyzing the flow characteristics in these configurations, it is found that (1) substantial area reduction leads to flow recirculation in both upstream and downstream of the stenosis and in the host artery near the toe, while diminishes the recirculation zone in the bypass graft near the bifurcation junction, (2) the asymmetry and position of the stenosis can affect the location and size of these recirculation zones, and (3) the curvature of the bypass graft can modify the fluid flow structure in the entire bypass system.


Asunto(s)
Anastomosis Arteriovenosa , Velocidad del Flujo Sanguíneo , Estenosis Coronaria/fisiopatología , Estenosis Coronaria/cirugía , Modelos Cardiovasculares , Animales , Presión Sanguínea , Simulación por Computador , Humanos
7.
Virology ; 286(1): 206-15, 2001 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-11448173

RESUMEN

Japanese encephalitis virus (JEV) infects a broad range of cell types in vitro, though little is known about the initial events of JEV infection. In the present study, we found that highly sulfated glycosaminoglycans (GAGs) are involved in infection of both neurovirulent (RP-9) and attenuated (RP-2ms) JEV strains. Competition experiments using highly sulfated GAGs, heparin and dextran sulfate, demonstrated an inhibition of JEV's attachment and subsequent infection of BHK-21 cells. Treatment of target cells by a potent sulfation inhibitor, sodium chlorate, greatly reduced viral binding ability as well as infection, suggesting a critical role of GAGs' sulfation status on the cellular surface in JEV infection. This phenomenon was confirmed by the manifestation of a distinct binding efficiency of JEV to the wild-type CHO cell line and its mutants with defects in GAG biosynthesis. We also demonstrated the binding of JEV particles and virus envelope glycoprotein to immobilized heparin beads. Furthermore, the addition of heparin suppressed the cytopathic effects induced by JEV infection in cultured cells. Our results establish that the highly sulfated form of GAGs on cell surfaces plays a determining role in the early stage of in vitro JEV infection.


Asunto(s)
Virus de la Encefalitis Japonesa (Especie)/fisiología , Encefalitis Japonesa/virología , Glicosaminoglicanos/fisiología , Animales , Línea Celular , Cricetinae , Humanos , Replicación Viral
8.
Zhonghua Yi Xue Za Zhi (Taipei) ; 63(7): 577-80, 2000 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10934812

RESUMEN

Henoch-Schönlein purpura (HSP) is a systemic vasculitis with manifestations usually involving the skin, gastrointestinal tract, kidney and joints. Epididymitis is rarely seen as a complication of HSP. It is easily misdiagnosed as testicular torsion, causing the patient to undergo unnecessary surgery, because the patient may have complained of severe scrotal pain and swelling. We report a 5-year-old boy who was suffering from HSP associated with acute scrotal pain and swelling of the left testicle. No gastrointestinal signs were noted but severe joint pain, swelling and palpable skin lesions in the lower limbs and the buttocks were found. Prednisolone was prescribed and the boy recovered without surgical intervention.


Asunto(s)
Epididimitis/etiología , Vasculitis por IgA/complicaciones , Escroto , Enfermedad Aguda , Preescolar , Humanos , Vasculitis por IgA/tratamiento farmacológico , Masculino , Prednisona/uso terapéutico
9.
Plasmid ; 43(3): 223-9, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10783301

RESUMEN

A 19-kb plasmid, pNI100, was isolated from Nocardia italica CCRC12359; its replicon was cloned and characterized as having a single open reading frame (ORF) of 1188 bp specifying 396 amino acids (aa). Analyses of the deduced aa sequence of the Rep protein indicated that characteristics of three consensus sequences and a P-loop-like motif in the Rep protein of plasmid pSG5, a conjugative plasmid involving a rolling-circle replication mechanism, were conserved in those of plasmid pNI100. Phenotypically, a pock structure was produced in the regenerated mycelium by introducing pNI100 DNA into the Streptomyces lividans protoplast. This result strongly suggests that pNI100 is a conjugative plasmid and probably replicates by a rolling-circle replication mechanism. By using the replicon of pNI100, a bifunctional plasmid pNI105 that could replicate in both Escherichia coli and S. lividans was constructed and found to be a useful cloning shuttle vector.


Asunto(s)
Proteínas de Unión al ADN , Nocardia/genética , Plásmidos/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , ADN Helicasas/genética , Replicación del ADN , Escherichia coli/genética , Datos de Secuencia Molecular , Mutación , Origen de Réplica , Homología de Secuencia de Aminoácido , Streptomyces/genética , Transactivadores/genética , Transformación Bacteriana/genética
10.
Changgeng Yi Xue Za Zhi ; 22(1): 133-7, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10418223

RESUMEN

Internal hernia, herniation of the internal organs through defects in the intraabdominal cavity, is rare. Due to the rarity of this pathology and lack of the specific symptoms and signs, early diagnosis and treatment are always stressful to the clinician and misdiagnoses may occur in the emergency room. The prognosis of a patient with uncomplicated internal hernia is excellent. We report a 21-year-old Chinese man with internal herniation through a defect of mesocolon, presented as an impalpable abdominal mass which was shown only on imaging studies. In addition to the typical whirlpool pattern, a huge solid mass between the pancreatic tail and stomach was found under computed tomography (CT) scan. The major symptoms were intermittent epigastralgia and abdominal fullness that had bothered him for years. Physical examination results showed only mild epigastric tenderness. Computed tomography scans and exploratory laparotomy of the abdomen played vital roles during diagnosis. The herniated organ was a portion of jejunum with partial small intestinal obstruction.


Asunto(s)
Hernia/diagnóstico , Enfermedades del Yeyuno/diagnóstico , Mesocolon , Adulto , Humanos , Masculino
11.
Zhonghua Yi Xue Za Zhi (Taipei) ; 62(3): 159-66, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10222604

RESUMEN

BACKGROUND: Cervical cancer is a worldwide malignancy particularly prevalent in older women. Due to the increasing population ratio of older women and their more complicated illnesses, doctors in Taiwan are concerned about the care of older patients with cervical cancer. Few studies have been performed on the association between referral initiative and illness severity upon referral as well as the tendency of older patients with cervical cancer to return to the referring doctor and to the consultant at the medical center for follow-up. The purpose of this study was to investigate the referral association by adjusting for confounding variables. METHODS: This study included 214 women aged 65 years and over with cervical cancer diagnosed between 1987 and 1995. Patients were referred to a tertiary teaching hospital by 71 primary care gynecologists. The International Federation of Gynecology and Obstetrics clinical stage and clinical severity were assessed in each patient. Histopathologic results were reviewed to confirm the diagnosis. RESULTS: Of all the cervical cancer referrals, 20.2% were initiated by patients or families and 79.8% were initiated by primary care doctors. No statistically significant differences were found in the Basic Activities of Daily Living or Instrumental Activities of Daily Living between doctor- and patient-initiated referrals. High Geriatric Depression Scale and low Mini-Mental State Examination were associated with doctor-initiated referrals. Higher cancer stage and greater clinical severity of patients with cervical cancer was found in patient- rather than doctor-initiated referrals. After adjusting for marriage, family type, medical payment, mental status, cancer stage and clinical severity, the data showed that, if the referral was initiated by a primary care doctor, older patients with cervical cancer had a similar likelihood to return to both the primary care doctor and the tertiary teaching hospital for follow-up. CONCLUSIONS: If a referral was initiated by a doctor, older women with cervical cancer were not only likely to return to their consulting physician at the medical center, but also likely to return to their primary care doctor. Continuous care is more likely to occur when the primary care doctor initiated the referral.


Asunto(s)
Derivación y Consulta , Neoplasias del Cuello Uterino/terapia , Anciano , Femenino , Humanos
12.
Circ Res ; 83(6): 668-78, 1998 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-9742063

RESUMEN

Mutations in the HERG gene are linked to the LQT2 form of the inherited long-QT syndrome. Transgenic mice were generated expressing high myocardial levels of a particularly severe form of LQT2-associated HERG mutation (G628S). Hearts from G628S mice appeared normal except for a modest enlargement seen only in females. Ventricular myocytes isolated from adult wild-type hearts consistently exhibited an inwardly rectifying E-4031-sensitive K+ current resembling the rapidly activating cardiac delayed rectifier K+ current (Ikr) in its time and voltage dependence; this current was not found in cells isolated from G628S mice. Action potential duration was significantly prolonged in single myocytes from G628S ventricle (cycle length=1 second, 26 degrees C) but not in recordings from intact ventricular strips studied at more physiological rates and temperature (200 to 400 bpm, 37 degrees C). ECG intervals, including QT duration, were unchanged, although minor aberrancies were noted in 20% (16/80) of the G628S mice studied, primarily involving the QRS complex and, more rarely, T-wave morphology. The aberrations were more commonly observed in females than males but could not be correlated with sex-based differences in action potential duration. These results establish the presence of IKr in the adult mouse ventricle and demonstrate the ability of the G628S mutation to exert a dominant negative effect on endogenous IKr in vivo, leading to the expected LQT2 phenotype of prolonged repolarization at the single cell level but not QT prolongation in the intact animal. The model may be useful in dissecting repolarization currents in the mouse heart and as a means of examining the mechanism(s) by which the G628S mutation exerts its dominant negative effect on native cardiac cells in vivo.


Asunto(s)
Proteínas de Transporte de Catión , Proteínas de Unión al ADN , Síndrome de QT Prolongado/genética , Bloqueadores de los Canales de Potasio , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Transactivadores , Potenciales de Acción/fisiología , Animales , Canales de Potasio de Tipo Rectificador Tardío , Modelos Animales de Enfermedad , Canal de Potasio ERG1 , Electrocardiografía , Canales de Potasio Éter-A-Go-Go , Femenino , Expresión Génica , Ventrículos Cardíacos/citología , Masculino , Ratones , Ratones Transgénicos , Modelos Cardiovasculares , Músculo Liso Vascular/citología , Mutación , Miocardio/patología , Canales de Potasio/fisiología , ARN Mensajero/genética , Función Ventricular
13.
J Cardiovasc Pharmacol ; 22(6): 857-62, 1993 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-7509905

RESUMEN

Long-chain acylcarnitines (LCA) have been shown to accumulate during myocardial ischemia and to contribute to malignant derangements characteristic of ischemia. We detail the time course of the increase in LCA levels during both ischemia and reperfusion. Evidence indicates an additional specific reperfusion-induced increase in LCA that peaks at 2 min and decreases to basal levels by 30 min. This increase in LCA during reperfusion is observed after 2-, 10-, or 20-min ischemia and is inhibited by the presence of the carnitine palmitoyl transferase 1 (CPT1) inhibitor phenyloxirane carboxylic acid (POCA). A role for increased LCA in mediating "reperfusion damage" is not indicated, however, because POCA did not attenuate either the incidence of ventricular fibrillation (VF) during early reperfusion or the survival rate of rats undergoing 24-h reperfusion after 10-min occlusion.


Asunto(s)
Carnitina O-Palmitoiltransferasa/metabolismo , Carnitina/metabolismo , Compuestos Epoxi/farmacología , Isquemia Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Animales , Compuestos Epoxi/química , Masculino , Peso Molecular , Ratas , Ratas Sprague-Dawley , Fibrilación Ventricular/inducido químicamente
14.
J Surg Oncol ; 49(4): 231-8, 1992 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1556867

RESUMEN

Radiation-induced intestinal injury is a dose limiting factor in the treatment of pelvic, abdominal, and retroperitoneal malignancies with radiation therapy. In experimental models, radiation has been associated with increased intestinal prostaglandin activity and in clinical trials prostaglandin inhibitors have been demonstrated to improve the symptoms of acute radiation enteritis. This study was conducted to determine if the prostaglandin inhibitor indomethacin could prevent the morphologic changes of acute radiation induced intestinal injury. Twenty-four male rats received either parenteral indomethacin at doses of 0.5, 1.0, and 3.0 mg/kg per dose every 12 hours or saline from 24 hours pre-radiation exposure until sacrifice 48 hours later. Twenty-four control animals received identical drug dosages and anesthesia but no radiation. Radiation produced a decreased villus/crypt ratio and increased acute inflammation and degeneration. Indomethacin treated animals demonstrated significantly less polymorphonuclear leukocyte infiltration and decreased degeneration. Villus/crypt ratio was not affected by indomethacin.


Asunto(s)
Indometacina/uso terapéutico , Enfermedades del Yeyuno/prevención & control , Traumatismos Experimentales por Radiación/prevención & control , Enfermedad Aguda , Animales , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos , Enteritis/patología , Enteritis/prevención & control , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/patología , Enfermedades del Yeyuno/patología , Yeyuno/efectos de los fármacos , Yeyuno/patología , Masculino , Antagonistas de Prostaglandina/uso terapéutico , Traumatismos Experimentales por Radiación/patología , Ratas , Ratas Endogámicas
15.
Horm Metab Res ; 23(1): 15-21, 1991 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-1826667

RESUMEN

The stability of growth-hormone releasing factor (growth regulating factor; GRF) analogs in porcine plasma was examined. GRF analogs were incubated in porcine plasma at 37 degrees C, extracted and subsequently analyzed using high performance liquid chromatography (HPLC). GRF(1-29)-NH2 was rapidly broken down in the plasma with a degradation rate of t1/2 = 13 min. The primary degradation product was identified as GRF(3-29)-NH2. Substitution of Gly15 by Ala15 slightly prolonged the plasma half-life (t1/2 = 17 min) and the major degradative fragment was found to be [Ala15]GRF(3-29)-NH2. The cleavage between the 2 and 3 position of the peptide was not inhibited by trasylol at a concentration of 1,000 KIU/ml but was dramatically reduced by the combined use of diprotin A and trasylol. Absence of the free amino group at the N-terminus and/or substitution of a D-amino acid residue at the penultimate position completely prevented cleavage between the 2 and 3 position in the structural linear GRF analogs. Side-chain to side-chain cyclization between Asp8 and Lys12 amino acid residues significantly improved the stability of GRF in plasma with t1/2 greater than 2 hr. An additional stability was provided by substitution of D-Ala2 for Ala2 in the structural cyclic analog. Cyclization between Lys21 and Asp25 also improved the stability of the GRF peptide in the plasma. Stability was further enhanced by the presence of D-Ala2 or by forming a dicyclic analog through an additional linkage between Asp8 and Lys12.


Asunto(s)
Hormona Liberadora de Hormona del Crecimiento/análogos & derivados , Porcinos/sangre , Secuencia de Aminoácidos , Animales , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Hormona Liberadora de Hormona del Crecimiento/sangre , Semivida , Datos de Secuencia Molecular , Fragmentos de Péptidos/sangre , Sermorelina
16.
Can J Physiol Pharmacol ; 65(12): 2472-82, 1987 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3449204

RESUMEN

The actions of 2,6-dimethyl-3,5-dicarbomethoxy-4-(2-isothiocyano)phenyl-1,4- dihydropyridine (o-NCS-DHP), a nifedipine analog bearing a reactive group, have been characterized in vitro by pharmacological and radioligand binding techniques in a number of smooth muscles and in vivo by blood pressure and radioligand binding. o-NCS-DHP exhibits persistent, but slowly reversible, antagonism in guinea pig ileal longitudinal smooth muscle, guinea pig bladder, taenia coli, rat portal vein, and rat tail artery to receptor responses (muscarinic and alpha-adrenoceptor) and K+ depolarization initiated responses. Duration of response was significantly longer than that of equivalent concentrations of nifedipine. In many tissues a component of antagonism produced by o-NCS-DHP was not reversed by repeated washing over the duration of the experiment (up to 2 or 7 h). A comparison of the actions of o-NCS-DHP and its isomers m-NCS-DHP and p-NCS-DHP revealed the former to be significantly longer lasting in rat tail artery against K+ depolarization induced responses. A similar profile was exhibited when the Ca2+ channel activator Bay K 8644 was employed as the stimulant, but the antagonism produced by all three compounds was fully reversed with sufficiently prolonged washing. In vivo administration of o-NCS-DHP (5-25 mg/kg) produced a persistent reduction of [3H]nitrendipine binding in rat brain, gut, and heart characterized as Bmax, but not KD, changes. No effects on [3H]dihydroalprenolol or [3H]quinuclidinyl benzilate binding were detected. Binding site recoveries were characterized by t1/2 values of 35-50 h, and these were significantly prolonged to 91-107 h in animals treated with cycloheximide. Recovery of [3H]nitrendipine binding sites correlated with blood pressure restoration in spontaneously hypertensive rats. These data suggest that o-NCS-DHP possesses both reversible and irreversible actions. The reversible actions are unusually persistent compared with nifedipine and other 1,4-dihydropyridine analogs. This persistent, but reversible component, may be accompanied by an irreversible action particularly at the higher concentrations employed in the in vivo experiments.


Asunto(s)
Bloqueadores de los Canales de Calcio/farmacología , Dihidropiridinas/farmacología , Isotiocianatos , Tiocianatos/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Bloqueadores de los Canales de Calcio/metabolismo , Bloqueadores de los Canales de Calcio/farmacocinética , Colon/efectos de los fármacos , Cobayas , Técnicas In Vitro , Masculino , Proteínas de la Membrana/metabolismo , Músculo Liso Vascular/efectos de los fármacos , Nitrendipino/metabolismo , Vena Porta/efectos de los fármacos , Potasio/farmacología , Quinuclidinil Bencilato , Ratas , Ratas Endogámicas SHR , Receptores Muscarínicos/efectos de los fármacos , Vejiga Urinaria/efectos de los fármacos
18.
J Pharmacol Exp Ther ; 239(1): 144-53, 1986 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-2428971

RESUMEN

The actions of the enantiomers of Bay K 8644 and 202-791 were studied in rat tail artery and guinea pig ileal longitudinal smooth muscle using pharmacologic and radioligand binding assays. (-)-(S)-Bay K 8644 (below 10(-7) M in rat tail artery and 3 X 10(-7) M in guinea pig ileum) and (+)-(S)-202-791 (below 10(-6) M) induced contractions and potentiated the responses to KCl depolarization in both smooth muscle preparations. In contrast, (+)-(R)-Bay K 8644 and (-)-(R)-202-791 inhibited the responses to KCl-induced depolarization. At higher concentrations, (-)-(S)-Bay K 8644 (10(-7) to 10(-6) M) and (+)-(S)-202-791 (10(-6) to 3 X 10(-5) M) in rat tail artery, and (-)-(S)-Bay K 8644 (3 X 10(-7) to 3 X 10(-6) M) in guinea pig ileal smooth muscle relaxed the tissues contracted maximally at lower concentrations of the same drug. Cross antagonism between 1,4-dihydropyridine activators was observed when (-)-(S)-Bay K 8644 (10(-7) to 10(-6) M) relaxed the maximum contraction in response to (+)-(S)-202-791. [3H]Nitrendipine bound in a tail arterial microsomal preparation to a single class of site, with KD of 3.63 X 10(-10) M and maximum binding of 552.7 fmol mg-1 protein. In both rat tail artery and guinea pig ileal smooth muscle, (-)-(S)-Bay K 8644, (+)-(R)-Bay K 8644, (+)-(S)-202-791 and (-)-(R)-202-791 inhibited specific [3H]nitrendipine binding competitively; the Kl values correlate well to the pharmacologic EC50 (for activators) or IC50 (for antagonists, measured against 80 mM KCl depolarization) values. The biphasic response to (-)-(S)-Bay K 8644 and (+)-(S)-202-791 suggests that the properties of Ca++ channel activation and antagonism may reside within a single 1,4-dihydropyridine molecule.


Asunto(s)
Ácido 3-piridinacarboxílico, 1,4-dihidro-2,6-dimetil-5-nitro-4-(2-(trifluorometil)fenil)-, Éster Metílico/metabolismo , Músculo Liso Vascular/metabolismo , Ácidos Nicotínicos/metabolismo , Oxadiazoles , Animales , Unión Competitiva , Calcio/metabolismo , Sinergismo Farmacológico , Cobayas , Canales Iónicos/metabolismo , Contracción Muscular/efectos de los fármacos , Nitrendipino/metabolismo , Cloruro de Potasio/farmacología , Ratas , Estereoisomerismo
19.
Can J Physiol Pharmacol ; 64(7): 909-21, 1986 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-2876766

RESUMEN

Postsynaptic alpha-adrenoceptors in the rat tail artery have been examined by determining the pA2 values for antagonists against several alpha-adrenoceptor agonists. In this tissue the alpha-adrenoceptor agonists all produce concentration-dependent mechanical responses with the following rank order of potency: clonidine greater than norepinephrine greater than phenylephrine greater than UK 14304 greater than B-HT 920. Antagonism by prazosin and yohimbine of phenylephrine, norepinephrine, and clonidine responses does not reveal the anticipated discrimination between alpha 1- and alpha 2-adrenoceptors. Thus, pA2 values for prazosin (9.1-9.5), yohimbine (7.2-7.4), and corynanthine (7.0-7.1) and idazoxan (7.6) do not show large differences between these receptor agonists and suggests the predominance of alpha 1-adrenoceptor mediated contractile responses in this preparation. Significant differences between antagonist activities (pA2 values) in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) artery preparations have not been observed. The sensitivity sequence of alpha-adrenoceptor agonist-induced responses to nifedipine and D 600 is B-HT 920 greater than clonidine greater than phenylephrine greater than norepinephrine. Dependence of agonist response upon extracellular Ca2+ parallels the sensitivity to Ca2+ channel antagonists. Sensitivity to D 600 of phenylephrine responses increased with decreasing concentration of phenylephrine or with receptor blockade by phenoxybenzamine: sensitivity of responses to B-HT 920 was not affected by these procedures. Tail artery strips from WKY and SHR do not exhibit major differences in sensitivity to D 600 or to Ca2+ depletion. Bay k 8644, a Ca2+ channel activator, produces concentration-dependent mechanical responses in the tail artery in the presence of modestly elevated K+ concentrations (10-15 mM): these actions of elevated K+ can be mimicked by both alpha 1- and alpha 2-adrenoceptor agonists including methoxamine, St 587, UK 14304, and clonidine. These studies do not provide clear evidence for the existence of discrete postsynaptic alpha 1- and alpha 2-adrenoceptor populations in rat tail artery as indicated by pA2 values or Ca2+ dependence of response.


Asunto(s)
Arterias/efectos de los fármacos , Hipertensión/fisiopatología , Músculo Liso Vascular/efectos de los fármacos , Receptores Adrenérgicos alfa/efectos de los fármacos , Agonistas alfa-Adrenérgicos/farmacología , Antagonistas Adrenérgicos alfa/farmacología , Animales , Bloqueadores de los Canales de Calcio/farmacología , Masculino , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Cola (estructura animal)/irrigación sanguínea
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