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1.
Nat Biomed Eng ; 6(11): 1298-1316, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-35835995

RESUMEN

A lack of comprehensive mapping of ganglionic inputs into the pancreas and of technology for the modulation of the activity of specific pancreatic nerves has hindered the study of how they regulate metabolic processes. Here we show that the pancreas-innervating neurons in sympathetic, parasympathetic and sensory ganglia can be mapped in detail by using tissue clearing and retrograde tracing (the tracing of neural connections from the synapse to the cell body), and that genetic payloads can be delivered via intrapancreatic injection to target sites in efferent pancreatic nerves in live mice through optimized adeno-associated viruses and neural-tissue-specific promoters. We also show that, in male mice, the targeted activation of parasympathetic cholinergic intrapancreatic ganglia and neurons doubled plasma-insulin levels and improved glucose tolerance, and that tolerance was impaired by stimulating pancreas-projecting sympathetic neurons. The ability to map the peripheral ganglia innervating the pancreas and to deliver transgenes to specific pancreas-projecting neurons will facilitate the examination of ganglionic inputs and the study of the roles of pancreatic efferent innervation in glucose metabolism.


Asunto(s)
Páncreas , Activación Viral , Ratones , Masculino , Animales , Páncreas/inervación , Páncreas/metabolismo , Neuronas/fisiología , Sinapsis , Glucosa/metabolismo
2.
Ann R Coll Surg Engl ; 101(5): 342-345, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-30854861

RESUMEN

INTRODUCTION: Total hip arthroplasty is recommended for elderly patients with fractured neck of femur who are independently mobile, have few co-morbidities and are not cognitively impaired. Providing a daily total hip arthroplasty service is challenging for some units in the UK and considering that these patients may be physiologically distinct from the average hip fracture patient, loss of the best practice tariff as a result of surgical delay may be unjustified. The aim of this study was to determine whether time to surgical intervention for patients eligible for total hip arthroplasty had a negative impact on patient complications, length of stay and functional outcomes. METHODS: All patients undergoing total hip arthroplasty for fractured neck of femur at our institution over a ten-year period were identified. Complications and functional outcomes were compared between patients receiving total hip arthroplasty before and after 36 hours. RESULTS: Of 112 consecutive patients undergoing total hip arthroplasty, 70 responded to a questionnaire or telephone consultation. Four patients were excluded owing to delayed presentation, the presence of advanced rheumatoid arthritis or a pathological fracture. Two-thirds (64%) of the remaining 66 patients underwent surgery within 36 hours of presentation. There were no significant differences between the groups of patients receiving surgery before or after 36 hours with regard to postoperative length of stay, complications, Oxford hip scores or visual analogue scale scores for state of health. CONCLUSIONS: Delaying surgery for patients eligible for total hip arthroplasty as per the National Institute for Health and Care Excellence guidelines is justified and should not incur loss of the best practice tariff.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Fracturas del Cuello Femoral/cirugía , Complicaciones Posoperatorias/etiología , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Tiempo de Internación/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/epidemiología , Recuperación de la Función , Estudios Retrospectivos , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
3.
Case Rep Womens Health ; 14: 6-7, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29593989

RESUMEN

BACKGROUND: Shoulder dystocia is an obstetric emergency which occurs in 0.2-3% of all births ACOG Committee on Practice Bulletins-Obstetrics and The American College of Obstetrician and Gynecologists (2002) . Symphysiotomy is a treatment option reserved primarily for developing countries where mortality rates of Cesarean delivery are 1-2% Monjok et al. (2013) . CASE: A G3P2002 with a history of two prior vaginal deliveries had a term delivery complicated by a severe shoulder dystocia. She underwent emergent symphysiotomy at an outside institution, with delivery of a dead macrosomic infant. She was transferred to our tertiary care center for further care. CONCLUSION: Symphysiotomy is rarely performed in the United States. We submit our postoperative management to add to the literature of this rarely performed obstetric intervention. PRÉCIS: Symphysiotomy for severe shoulder dystocia is rarely utilized in the United States. We describe a case of symphysiotomy done for severe shoulder dystocia at an outside institution, and the patient's subsequent care at our institution.

4.
Epidemiol Infect ; 142(1): 134-41, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23594431

RESUMEN

Little information is available about perceptions of influenza vaccination of parents with healthy children in daycare. Therefore, we systematically explored the relationship between parental risk perception and influenza vaccination in children attending daycare. We distributed a self-administered paper survey to parents of children aged 6-59 months attending licensed daycare centres in Tarrant County, Texas. We used conditional logistic regression with penalized conditional likelihood to estimate odds ratios (ORs) and 95% profile likelihood confidence limits (PL) for parental risk-perception factors and influenza vaccination. A high level of parental prevention behaviours (OR 9.1, 95% PL 3.2, 31) and physician recommendation (OR 8.2, 95% PL 2.7, 30) had the highest magnitudes of association with influenza vaccination of healthy children in daycare. Our results provide evidence about critical determinants of influenza vaccination of healthy children in daycare, which could help inform public health interventions aimed at increasing influenza vaccination coverage in this population.


Asunto(s)
Guarderías Infantiles/estadística & datos numéricos , Conocimientos, Actitudes y Práctica en Salud , Vacunas contra la Influenza/administración & dosificación , Padres/psicología , Aceptación de la Atención de Salud/psicología , Vacunación/psicología , Vacunación/estadística & datos numéricos , Adulto , Preescolar , Femenino , Humanos , Lactante , Gripe Humana/prevención & control , Modelos Logísticos , Masculino , Oportunidad Relativa , Encuestas y Cuestionarios , Texas/epidemiología
5.
Occup Med (Lond) ; 63(8): 575-8, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24213094

RESUMEN

BACKGROUND: The 'fit note' was introduced in the UK in April 2010, to facilitate return to work (RTW). However, no research to date has reported on how general practitioners (GPs) complete the comments section of the fit note. AIMS: To investigate the content of GPs' comments in a sample of actual fit notes. METHODS: Data were collected in a service evaluation of fit notes issued by a regular general practice and those issued by a fit for work service (FFWS), where the fit notes for patients using the service are signed by GPs who have completed or are studying for a Diploma in Occupational Medicine. Content analysis was conducted on the fit note comments. RESULTS: There were 1212 fit notes available for analysis. Seven hundred and twelve were issued by the general practice and 500 by the FFWS. The FFWS made comments in 98% of those who may be fit and 90% of those not fit against 72% and 12%, respectively, for comments by the general practice. Fourteen different categories were identified in the comments. Most comments made some reference to RTW but few described the functional effects of the patient's condition. Comments frequently covered more than one category and appeared to be serving a number of different purposes. CONCLUSIONS: There was a wide variety in how the comments section was completed, and GPs were not completing the fit note as intended. The information provided may require improvement if it is to be useful to employers.


Asunto(s)
Actitud del Personal de Salud , Médicos Generales/psicología , Ausencia por Enfermedad , Evaluación de Capacidad de Trabajo , Humanos , Registros Médicos/normas , Medicina del Trabajo/educación , Relaciones Médico-Paciente
6.
Br Dent J ; 212(3): 105, 2012 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-22322747
7.
Br Dent J ; 210(4): 151, 2011 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-21350515
8.
Clin Endocrinol (Oxf) ; 73(4): 497-501, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20560981

RESUMEN

BACKGROUND: Low high-density lipoprotein (HDL) cholesterol and particle concentration are risk factors for coronary heart disease in women. Tibolone lowers HDL cholesterol and HDL particle concentration, an effect that could be reversed by the peroxisome proliferator-activator receptor-α agonist fenofibrate. OBJECTIVE: To assess the effects of fenofibrate on plasma HDL particles in postmenopausal women taking tibolone therapy. DESIGN AND PARTICIPANTS: Randomized crossover study conducted in a women's health clinic. Fourteen postmenopausal women taking tibolone 2.5 mg daily for menopausal symptoms were randomized to either fenofibrate 160 mg daily or no treatment for 8 weeks, followed by a 3-week wash-out for fenofibrate and then crossed over to alternate therapy for another 8 weeks. The main outcome measure was changes in plasma HDL cholesterol concentration, apoA-I and apoA-II, LpA-I and LpA-I-A-II. RESULTS: After 8 weeks of fenofibrate therapy, there was no change in HDL cholesterol, 1.13 ± 0.06 v 1.16 ± 0.06 mmol/l (P = 0.47) or apoA-I, 1.19 ± 0.05 v 1.20 ± 0.05 g/l (P = 0.23). LpA-I fell significantly 0.35 ± 0.03 v 0.29 ± 0.02 (P = 0.02) but there was a rise in apoA-II, 0.35 ± 0.01 v 0.39 ± 0.01 g/l (P = 0.01). There was a significant fall in total cholesterol, triglycerides, low-density lipoprotein cholesterol and apoB. CONCLUSION: In women taking tibolone, fenofibrate increases plasma apoA-II concentration and effects a redistribution of HDL subfractions but does not correct tibolone-induced changes in HDL cholesterol or HDL particle concentration. The mechanism and significance of this require further investigation.


Asunto(s)
HDL-Colesterol/sangre , Moduladores de los Receptores de Estrógeno/efectos adversos , Fenofibrato/farmacología , Sofocos/tratamiento farmacológico , Hipolipemiantes/farmacología , Lipoproteínas HDL/sangre , Norpregnenos/efectos adversos , Anciano , Apolipoproteína A-II/sangre , Estudios Cruzados , Femenino , Humanos , Persona de Mediana Edad , Posmenopausia
9.
Hypertens Pregnancy ; 29(1): 54-68, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19909212

RESUMEN

OBJECTIVES: To identify correlates of a prolonged length of stay (PLOS) in women hospitalized for preeclampsia/eclampsia in Texas, USA. METHODS: Statewide hospital data were obtained, and the records of women who were discharged in 2004 and/or 2005 with a principal discharge diagnosis of preeclampsia or eclampsia were extracted using ICD-9-CM codes. PLOS was defined as a stay greater than 5 days. Odds ratios (OR) for PLOS were calculated. Generalized estimating equations were used to account for a small group of women who were hospitalized multiple times during the study period for preeclampsia. A total of 21,203 records were analyzed. RESULTS: The crude incidence of PLOS was 17.5%. Advancing maternal age was positively associated with PLOS: for every 10-year increase, there was a 20% increase in the odds of PLOS (adjusted OR = 1.20,95% confidence interval (CI): 1.13, 1.28). The strongest risk factor for PLOS was the presence of renal disease: adjusted OR 5.81 (95% CI: 3.97, 8.50). Protective factors included Medicaid beneficiary status, and being admitted from the emergency department. CONCLUSIONS: The strongest correlate of PLOS in a large cohort of women hospitalized for preeclampsia was the presence of renal disease.


Asunto(s)
Eclampsia/epidemiología , Enfermedades Renales/epidemiología , Preeclampsia/epidemiología , Comorbilidad , Intervalos de Confianza , Femenino , Humanos , Clasificación Internacional de Enfermedades , Tiempo de Internación , Edad Materna , Medicaid , Oportunidad Relativa , Alta del Paciente , Embarazo , Medición de Riesgo , Factores de Riesgo , Índice de Severidad de la Enfermedad , Texas , Estados Unidos
10.
Contraception ; 77(6): 415-9, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18477490

RESUMEN

BACKGROUND: This retrospective analysis evaluated the association of age and weight with cycle control in women using either of two formulations of low-estrogen-dose oral contraceptives. STUDY DESIGN: Data for this secondary analysis were derived from a randomized multicenter trial assessing the efficacy and safety of norgestimate (NGM) 180/215/250 mcg/ethinyl estradiol (EE) 25 mcg (n=1506) and norethindrone acetate 1 mg/EE 20 mcg (n=1057). In this retrospective analysis, the incidence of breakthrough bleeding/spotting (BTB/S) was evaluated in women stratified by age (18-24, 25-34 and >34 years) and weight (155 lb). RESULTS: A lower percentage of women experienced BTB/S with NGM/EE during most cycles, regardless of age or weight, compared with norethindrone acetate/EE. At Cycle 6, the incidences of BTB/S for NGM/EE versus norethindrone acetate/EE were as follows: 18-24 years, 10.9% versus 29.7% (p<.0001); 25-34 years, 10.9% versus 18.6% (p<.001); >34 years, 8.1% versus 19.1% (p<.005); 155 lb, 10.0% versus 18.3% (p<.01). CONCLUSION: NGM/EE provided better cycle control as defined by BTB/S compared with norethindrone acetate/EE, regardless of subject age or weight for six cycles.


Asunto(s)
Anticonceptivos Orales Combinados/farmacología , Anticonceptivos Sintéticos Orales/farmacología , Estrógenos/farmacología , Etinilestradiol/farmacología , Menstruación/efectos de los fármacos , Adolescente , Adulto , Factores de Edad , Peso Corporal , Femenino , Humanos , Metrorragia/inducido químicamente , Persona de Mediana Edad , Noretindrona/farmacología , Norgestrel/análogos & derivados , Norgestrel/farmacología , Estudios Retrospectivos , Resultado del Tratamiento
11.
J Econ Entomol ; 98(6): 1816-23, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16539099

RESUMEN

After characterization of the natural spread of necrosis-inducing Bean yellow mosaic potyvirus (family Potyviridae, genus Potyvirus, BYMV(N)), nonpersistently transmitted from clover, Trifolium repens L., to an adjacent field of snap bean, Phaseolus vulgaris L., in western Oregon, we established a study site enabling us to investigate the virus reservoir, to observe en masse transmission of BYMV(N) to bean plants, and to identify aphid species associated with virus spread. Colonies of Myzus persicae (Sulzer), Acyrthosiphon pisum (Harris), and Aphis fabae Scopoli associated with virus spread were established in an insectary and shown to vector this virus. Although Nearctaphis bakeri (Cowen) comprised 68% of aphid alatae taken from bean leaves during virus spread, we were unable to show that this species could vector the virus by using the same methods that were successful for the other species. Instead, we found that when two distinct N. bakeri colonies unexpectedly emerged from the roots of T. repens BYMV(N) source plants (WZwc #6 and #11) that were present in the laboratory (insectary), these aphids transmitted BYMVN at rates comparable with those of M. persicae and A. pisum. Transmission of BYMVN also occurred with two other N. bakeri colonies maintained for 4 mo on Trifolium pratense L. (NZwc Sch 3B and Sch 7C) BYMVN source plants. Each of these four BYMVN transmission successes also demonstrated an unprecedented once-only transmission of BYMV(N) by N. bakeri colonies. Our experience with western Oregon N. bakeri colonies was compared with descriptions of this native North American species after its 1960-1980s arrival in France, Germany, and Italy.


Asunto(s)
Áfidos/virología , Fabaceae/virología , Enfermedades de las Plantas/virología , Potyvirus , Trifolium/virología , Animales , Especificidad de la Especie
12.
Spinal Cord ; 42(8): 450-8, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15037861

RESUMEN

STUDY DESIGN: Retrospective case series. OBJECTIVES: Respiratory disorders are the leading cause of death in persons with spinal cord injury (SCI), but the epidemiology and medical management of pneumonia in persons with chronic SCI is not well characterized. We describe the clinical presentation of persons with SCI with community-acquired pneumonia (CAP), characterize its management and compare practice to recommendations for CAP in the general population. SETTING: Three United States Veterans Affairs Medical Centers with specialized SCI services. METHODS: Chart abstraction was performed for all persons with chronic SCI seen at participating centers for treatment of CAP during a 2-year period. Collected data included presenting signs and symptoms, laboratory and imaging results, initial antibiotic therapy, secretion mobilization techniques, in-patient vs outpatient management, length of stay, and mortality. RESULTS: In all, 41 persons with SCI received treatment for CAP during the study period. A total of 32 (78.0%) patients were admitted for treatment; two (4.8%) required intubation and mechanical ventilation. Initial antibiotic coverage met guideline recommendations for only half of inpatients and infrequently provided adequate antipseudomonal coverage. Microbiologic testing was performed on 26 cases (63.4%) and demonstrated a specific pathogen in only five cases (12.2% of total). Three cases (7.3%) died during treatment for CAP, and 16 (42.1%) of 38 CAP survivors died within a median follow-up of 3 years. CONCLUSION: The majority of chronic SCI patients who present to specialized SCI centers with CAP are admitted for treatment. Short-term mortality is comparable to CAP in the general population.


Asunto(s)
Neumonía/microbiología , Neumonía/terapia , Traumatismos de la Médula Espinal/fisiopatología , Adulto , Anciano , Antibacterianos/uso terapéutico , Infecciones Comunitarias Adquiridas/microbiología , Infecciones Comunitarias Adquiridas/mortalidad , Infecciones Comunitarias Adquiridas/terapia , Diagnóstico Diferencial , Femenino , Unidades Hospitalarias/estadística & datos numéricos , Hospitales de Veteranos/estadística & datos numéricos , Humanos , Masculino , Persona de Mediana Edad , Neumonía/mortalidad , Guías de Práctica Clínica como Asunto , Infecciones por Pseudomonas/diagnóstico , Infecciones por Pseudomonas/terapia , Estudios Retrospectivos , Traumatismos de la Médula Espinal/complicaciones , Estados Unidos
13.
Mol Biol Cell ; 12(12): 4114-28, 2001 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11739805

RESUMEN

We isolated a temperature-sensitive mutant, hrd4-1, deficient in ER-associated degradation (ERAD). The HRD4 gene was identical to NPL4, a gene previously implicated in nuclear transport. Using a diverse set of substrates and direct ubiquitination assays, our analysis revealed that HRD4/NPL4 is required for a poorly characterized step in ERAD after ubiquitination of target proteins but before their recognition by the 26S proteasome. Our data indicate that this lack of proteasomal processing of ubiquitinated proteins constitutes the primary defect in hrd4/npl4 mutant cells and explains the diverse set of hrd4/npl4 phenotypes. We also found that each member of the Cdc48p-Ufd1p-Npl4p complex is individually required for ERAD.


Asunto(s)
Cisteína Endopeptidasas/metabolismo , Retículo Endoplásmico/química , Retículo Endoplásmico/metabolismo , Complejos Multienzimáticos/metabolismo , Proteínas de Complejo Poro Nuclear , Proteínas Nucleares/metabolismo , Procesamiento Proteico-Postraduccional , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Ubiquitina/metabolismo , Transporte Activo de Núcleo Celular , Adenosina Trifosfatasas , Proteínas de Ciclo Celular/metabolismo , Ácidos Grasos Insaturados/metabolismo , Citometría de Flujo , Mutación , Proteínas Nucleares/genética , Proteínas de Transporte Nucleocitoplasmático , Complejo de la Endopetidasa Proteasomal , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteína que Contiene Valosina , Proteínas de Transporte Vesicular
14.
Contraception ; 63(6): 289-95, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11672549

RESUMEN

This multicenter study compared the contraceptive efficacy, cycle control, and safety of a new triphasic norgestimate (180/215/250 microg)/ethinyl estradiol 25 microg regimen (Ortho Tri-Cyclen Lo) (n = 1,723) with that of norethindrone acetate 1 mg/ethinyl estradiol 20 microg (Loestrin Fe 1/20) (n = 1,171). Healthy women were treated for up to 13 cycles. Demographics were similar between regimens. Contraceptive efficacy was comparable for Ortho Tri-Cyclen Lo and Loestrin Fe 1/20. The overall and method failure probabilities of pregnancy through 13 cycles were 1.9% and 1.5%, respectively, with Ortho Tri-Cyclen Lo and 2.6% and 2.4%, respectively, with Loestrin Fe 1/20. Breakthrough bleeding and spotting was reported by a significantly lower percentage of participants in the Ortho Tri-Cyclen Lo group compared with the Loestrin Fe 1/20 group. At representative Cycles 1, 3, 6, 9, and 13, breakthrough bleeding and spotting rates were 16.3, 11.5, 10.3, 7.9, and 7.7%, respectively, in the Ortho Tri-Cyclen Lo group and 34.9, 22.9, 22.2, 15.9, and 13.1%, respectively, in the Loestrin Fe 1/20 group. Compliance and safety data were similar for the two regimens.


Asunto(s)
Anticonceptivos Orales Combinados/administración & dosificación , Anticonceptivos Orales Combinados/efectos adversos , Combinación Etinil Estradiol-Norgestrel/administración & dosificación , Combinación Etinil Estradiol-Norgestrel/efectos adversos , Etinilestradiol/administración & dosificación , Etinilestradiol/efectos adversos , Noretindrona/administración & dosificación , Noretindrona/efectos adversos , Norgestrel/análogos & derivados , Norgestrel/administración & dosificación , Norgestrel/efectos adversos , Administración Oral , Adolescente , Adulto , Combinación de Medicamentos , Femenino , Humanos , Ciclo Menstrual/efectos de los fármacos , Persona de Mediana Edad , Cooperación del Paciente , Embarazo , Factores de Tiempo , Resultado del Tratamiento
15.
Dermatol Surg ; 27(9): 837-40, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11553174

RESUMEN

Glomangiosarcoma, or malignant glomus tumor, is a very rare neoplasm that when seen typically arises from a benign glomus tumor. Despite having histologic features of malignancy, these tumors usually do not metastasize. However, when metastasis occurs this disease is often fatal. We report a case of a malignant glomus tumor arising de novo on the nose of an 89-year-old white woman, and we review the literature concerning glomangiosarcomas.


Asunto(s)
Tumor Glómico/patología , Neoplasias Nasales/patología , Neoplasias Cutáneas/patología , Anciano , Anciano de 80 o más Años , Femenino , Tumor Glómico/cirugía , Humanos , Cirugía de Mohs , Neoplasias Nasales/cirugía , Piel/patología , Neoplasias Cutáneas/cirugía
16.
AIDS Res Hum Retroviruses ; 17(11): 1009-19, 2001 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-11485618

RESUMEN

In a previous study we showed that budding of HIV-1 particles occurs at highly specialized membrane microdomains known as lipid rafts. These microdomains are characterized by a distinct lipid composition that includes high concentrations of cholesterol, sphingolipids, and glycolipids. Since cholesterol is known to play a key role in the entry of some other viruses, our observation of HIV budding from lipid rafts led us to investigate the role in HIV-1 entry of cholesterol and lipid rafts in the plasma membrane of susceptible cells. We have used 2-OH-propyl-beta-cyclodextrin (beta-cyclodextrin) to deplete cellular cholesterol and disperse lipid rafts. Our results show that removal of cellular cholesterol rendered primary cells and cell lines highly resistant to HIV-1-mediated syncytium formation and to infection by both CXCR4- and CCR5-specific viruses. beta-Cyclodextrin treatment of cells partially reduced HIV-1 binding, while rendering chemokine receptors highly sensitive to antibody-mediated internalization. There was no effect on CD4 expression. All of the above-described effects were readily reversed by incubating cholesterol-depleted cells with low concentrations of cholesterol-loaded beta-cyclodextrin to restore cholesterol levels. Cholesterol depletion made cells resistant to SDF-1-induced binding to ICAM-1 through LFA-1. Since LFA-1 contributes significantly to cell binding by HIV-1, this latter effect may have contributed to the observed reduction in HIV-1 binding to cells after treatment with beta-cyclodextrin. Our results indicate that cholesterol may be critical to the HIV-1 coreceptor function of chemokine receptors and is required for infection of cells by HIV-1.


Asunto(s)
Colesterol/metabolismo , Infecciones por VIH/metabolismo , VIH-1/crecimiento & desarrollo , Microdominios de Membrana/metabolismo , beta-Ciclodextrinas , Línea Celular , Ciclodextrinas/farmacología , Humanos , Células Jurkat , Microdominios de Membrana/química , Microdominios de Membrana/efectos de los fármacos , Unión Proteica , Receptores CCR5/metabolismo , Receptores CXCR4/metabolismo , Células Tumorales Cultivadas
17.
Mol Cell Biol ; 21(13): 4276-91, 2001 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-11390656

RESUMEN

Ubiquitination is used to target both normal proteins for specific regulated degradation and misfolded proteins for purposes of quality control destruction. Ubiquitin ligases, or E3 proteins, promote ubiquitination by effecting the specific transfer of ubiquitin from the correct ubiquitin-conjugating enzyme, or E2 protein, to the target substrate. Substrate specificity is usually determined by specific sequence determinants, or degrons, in the target substrate that are recognized by the ubiquitin ligase. In quality control, however, a potentially vast collection of proteins with characteristic hallmarks of misfolding or misassembly are targeted with high specificity despite the lack of any sequence similarity between substrates. In order to understand the mechanisms of quality control ubiquitination, we have focused our attention on the first characterized quality control ubiquitin ligase, the HRD complex, which is responsible for the endoplasmic reticulum (ER)-associated degradation (ERAD) of numerous ER-resident proteins. Using an in vivo cross-linking assay, we directly examined the association of the separate HRD complex components with various ERAD substrates. We have discovered that the HRD ubiquitin ligase complex associates with both ERAD substrates and stable proteins, but only mediates ubiquitin-conjugating enzyme association with ERAD substrates. Our studies with the sterol pathway-regulated ERAD substrate Hmg2p, an isozyme of the yeast cholesterol biosynthetic enzyme HMG-coenzyme A reductase (HMGR), indicated that the HRD complex discerns between a degradation-competent "misfolded" state and a stable, tightly folded state. Thus, it appears that the physiologically regulated, HRD-dependent degradation of HMGR is effected by a programmed structural transition from a stable protein to a quality control substrate.


Asunto(s)
Retículo Endoplásmico/metabolismo , Hidroximetilglutaril-CoA Reductasas/metabolismo , Ligasas/metabolismo , Glicoproteínas de Membrana/metabolismo , Unión Proteica/efectos de los fármacos , Proteínas de Saccharomyces cerevisiae , Enzimas Ubiquitina-Conjugadoras , Animales , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Retículo Endoplásmico/química , Inhibidores Enzimáticos/farmacología , Citometría de Flujo , Proteínas Fúngicas/metabolismo , Glicerol/farmacología , Hidroximetilglutaril-CoA Reductasas/química , Hidroximetilglutaril-CoA Reductasas/genética , Isoenzimas/genética , Isoenzimas/metabolismo , Ligasas/genética , Lovastatina/farmacología , Sustancias Macromoleculares , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Conformación Proteica , Pliegue de Proteína , Saccharomyces cerevisiae/genética , Esteroles/biosíntesis , Especificidad por Sustrato , Ácidos Tricarboxílicos/farmacología , Tripsina/metabolismo , Ubiquitina-Proteína Ligasas
18.
Proc Natl Acad Sci U S A ; 98(9): 5359-62, 2001 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-11274360

RESUMEN

Humans are consciously aware of some memories and can make verbal reports about these memories. Other memories cannot be brought to consciousness, even though they influence behavior. This conspicuous difference in access to memories is central in taxonomies of human memory systems but has been difficult to document in animal studies, suggesting that some forms of memory may be unique to humans. Here I show that rhesus macaque monkeys can report the presence or absence of memory. Although it is probably impossible to document subjective, conscious properties of memory in nonverbal animals, this result objectively demonstrates an important functional parallel with human conscious memory. Animals able to discern the presence and absence of memory should improve accuracy if allowed to decline memory tests when they have forgotten, and should decline tests most frequently when memory is attenuated experimentally. One of two monkeys examined unequivocally met these criteria under all test conditions, whereas the second monkey met them in all but one case. Probe tests were used to rule out "cueing" by a wide variety of environmental and behavioral stimuli, leaving detection of the absence of memory per se as the most likely mechanism underlying the monkeys' abilities to selectively decline memory tests when they had forgotten.


Asunto(s)
Cognición/fisiología , Macaca mulatta/fisiología , Macaca mulatta/psicología , Memoria/fisiología , Animales , Conducta de Elección/fisiología , Señales (Psicología) , Preferencias Alimentarias/psicología , Masculino , Probabilidad , Pruebas Psicológicas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
19.
J Biol Chem ; 276(12): 8681-94, 2001 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-11134013

RESUMEN

Sterol synthesis by the mevalonate pathway is modulated, in part, through feedback-regulated degradation of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR). In mammals, both a non-sterol isoprenoid signal derived from farnesyl diphosphate (FPP) and a sterol-derived signal appear to act together to positively regulate the rate of HMGR degradation. Although the nature and number of sterol-derived signals are not clear, there is growing evidence that oxysterols can serve in this capacity. In yeast, a similar non-sterol isoprenoid signal generated from FPP acts to positively regulate HMGR degradation, but the existence of any sterol-derived signal has thus far not been revealed. We now demonstrate, through the use of genetic and pharmacological manipulation of oxidosqualene-lanosterol cyclase, that an oxysterol-derived signal positively regulated HMGR degradation in yeast. The oxysterol-derived signal acted by specifically modulating HMGR stability, not endoplasmic reticulum-associated degradation in general. Direct biochemical labeling of mevalonate pathway products confirmed that oxysterols were produced endogenously in yeast and that their levels varied appropriately in response to genetic or pharmacological manipulations that altered HMGR stability. Genetic manipulation of oxidosqualene-lanosterol cyclase did result in the buildup of detectable levels of 24,25-oxidolanosterol by gas chromatography, gas chromatography-mass spectroscopy, and NMR analyses, whereas no detectable amounts were observed in wild-type cells or cells with squalene epoxidase down-regulated. In contrast to mammalian cells, the yeast oxysterol-derived signal was not required for HMGR degradation in yeast. Rather, the function of this second signal was to enhance the ability of the FPP-derived signal to promote HMGR degradation. Thus, although differences do exist, both yeast and mammalian cells employ a similar strategy of multi-input regulation of HMGR degradation.


Asunto(s)
Hidroximetilglutaril-CoA Reductasas/metabolismo , Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Esteroles/metabolismo , Regulación hacia Abajo , Hidrólisis , Hidroximetilglutaril-CoA Reductasas/genética , Transferasas Intramoleculares/antagonistas & inhibidores , Transferasas Intramoleculares/metabolismo , Biosíntesis de Proteínas , Transcripción Genética , Ubiquitinas/metabolismo
20.
Nat Cell Biol ; 3(1): 24-9, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11146622

RESUMEN

In eukaryotes, endoplasmic reticulum-associated degradation (ERAD) functions in cellular quality control and regulation of normal ER-resident proteins. ERAD proceeds by the ubiquitin-proteasome pathway, in which the covalent attachment of ubiquitin to proteins targets them for proteasomal degradation. Ubiquitin-protein ligases (E3s) play a crucial role in this process by recognizing target proteins and initiating their ubiquitination. Here we show that Hrd1p, which is identical to Der3p, is an E3 for ERAD. Hrd1p is required for the degradation and ubiquitination of several ERAD substrates and physically associates with relevant ubiquitin-conjugating enzymes (E2s). A soluble Hrd1 fusion protein shows E3 activity in vitro - catalysing the ubiquitination of itself and test proteins. In this capacity, Hrd1p has an apparent preference for misfolded proteins. We also show that Hrd1p functions as an E3 in vivo, using only Ubc7p or Ubc1p to specifically program the ubiquitination of ERAD substrates.


Asunto(s)
Retículo Endoplásmico/metabolismo , Membranas Intracelulares/metabolismo , Ligasas/metabolismo , Proteínas/metabolismo , Proteínas de Saccharomyces cerevisiae , Enzimas Ubiquitina-Conjugadoras , Ubiquitinas/metabolismo , Catálisis , Cisteína Endopeptidasas/metabolismo , Retículo Endoplásmico/ultraestructura , Proteínas del Grupo de Alta Movilidad/metabolismo , Membranas Intracelulares/ultraestructura , Complejos Multienzimáticos/metabolismo , Fenotipo , Complejo de la Endopetidasa Proteasomal , Estructura Terciaria de Proteína/fisiología , Ubiquitina-Proteína Ligasas , Levaduras
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