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1.
Osteoporos Int ; 35(6): 951-969, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38300316

RESUMEN

Fracture liaison services (FLS) have been proven clinically effective and cost-effective in preventing subsequent fractures among patients with an existing fragility fracture. Little is known about their monetary benefits such as their return on investment (ROI). This systematic review aimed to investigate the ROI of FLS and identify the FLS characteristics with better ROI. Studies on the cost-effectiveness of FLS published between January 2000 and December 2022 were searched from MEDLINE, EMBASE, PubMed, and Cochrane Central. Two independent reviewers conducted study selection and data extraction. ROI was calculated based on the difference between monetary benefits and FLS costs divided by the FLS costs. Subgroup analysis of ROI was performed across FLS types and FLS design details. A total of 23 FLS were included in this review. The majority of them were targeting patients aged over 50 years having fractures without identified sites. The mean ROI of these FLS was 10.49 (with a median ROI of 7.57), and 86.96% of FLS had positive ROI. FLS making treatment recommendations yielded the highest ROI (with a mean ROI of 18.39 and a median of 13.60). Incorporating primary care providers (with a mean ROI of 16.04 and a median of 13.20) or having them as program leaders (with a mean ROI of 12.07 and a median of 12.07) has demonstrated a high ROI. FLS for specific fracture sites had great monetary return. Intensive FLS such as type A and B FLS programs had higher ROI than non-intensive type C and D FLS. This review revealed a 10.49-fold monetary return of FLS. Identified characteristics contributing to greater economic return informed value-for-money FLS designs. Findings highlight the importance of FLS and the feasibility of expanding their contribution in mitigating the economic burden of osteoporotic fracture and are conducive to the promotion of FLS internationally.


Asunto(s)
Análisis Costo-Beneficio , Fracturas Osteoporóticas , Humanos , Fracturas Osteoporóticas/prevención & control , Fracturas Osteoporóticas/economía , Costos de la Atención en Salud/estadística & datos numéricos , Prevención Secundaria/organización & administración , Prevención Secundaria/economía
2.
Acta Anaesthesiol Scand ; 62(5): 588-599, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29573399

RESUMEN

BACKGROUND: Impaired cerebrovascular autoregulation (CVAR) is observed in up to 20% of cardiac surgical patients. This systematic review aims to evaluate the association between impaired CVAR, measured by current monitoring techniques, and patient-centred outcomes in adults following cardiac surgery. METHODS: MEDLINE, EMBASE, PubMed, MEDLINE In-Process and Cochrane Library were systematically searched through 8 December 2017. Studies were included if they assessed associations between CVAR and patient-centred outcomes in the adult cardiac surgical population. The primary outcome of this systematic review was mortality. Secondary outcomes were stroke, delirium and acute kidney injury. Risk of bias was systematically assessed, and the GRADE methodology was used to evaluate the quality of evidence across outcomes. RESULTS: Eleven observational studies and no randomised controlled trials met the inclusion criteria. Due to methodological heterogeneity, meta-analysis was not possible. There was a high risk of bias within individual studies and low quality of evidence across outcomes. Of the included studies, one assessed mortality, five assessed stroke, four assessed delirium, and three assessed acute kidney injury. No reliable conclusions can be drawn from the one study assessing mortality. Interpretation of studies investigating CVAR and stroke, delirium and acute kidney injury was complicated by the lack of standardisation of monitoring techniques as well as varying definitions of impaired CVAR. CONCLUSIONS: There is a paucity of high quality evidence for CVAR monitoring and its associations with outcome measures in post-cardiac surgical patients, highlighting the need for future studies.


Asunto(s)
Procedimientos Quirúrgicos Cardíacos/efectos adversos , Circulación Cerebrovascular/fisiología , Homeostasis/fisiología , Lesión Renal Aguda/etiología , Procedimientos Quirúrgicos Cardíacos/mortalidad , Delirio/etiología , Humanos , Evaluación de Resultado en la Atención de Salud , Accidente Cerebrovascular/etiología
3.
J Neurol ; 271(9): 6038-6044, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39030458

RESUMEN

INTRODUCTION: Ubiquitin C-terminal hydrolase L1 (UCHL1) has been associated with a severe, complex autosomal recessive spastic paraplegia (HSP79) [1] [2] [3] [4]. More recently, UCHL1 loss of function (LoF) variants have been associated to an autosomal dominant disease characterized by late-onset spastic ataxia, neuropathy, and frequent optic atrophy [5]. METHODS: Routine clinical care whole-genome (WGS) and exome (ES) sequencing. RESULTS: We present three families with autosomal dominant UCHL1-related disorder. The clinical phenotype mainly associated optic atrophy, mixed cerebellar and sensory ataxia, and possible hearing loss. We delineated two major phenotypes, even within the same family: (1) juvenile severe optic atrophy followed by a later-onset ataxia, or (2) late-onset ataxia with asymptomatic or mild optic atrophy. The families harboured three novel heterozygous variants in UCHL1: two loss of function (p.Lys115AsnfsTer40; c.171_174 + 7del11), and one missense (p.Asp176Asn) involving the catalytic site of the protein and potentially altering the adjacent splice site. DISCUSSION: We confirm the existence of dominantly inherited UCHL1 pathogenic variants. We describe a considerable intrafamilial phenotypic variability, with two main phenotypes. Optic atrophy was consistently present, but with varying degrees of severity. Neither delayed motor or intellectual development, nor dysmorphic features were part of the dominant phenotype in comparison with the autosomal recessive form. The molecular mechanism appears to be haploinsufficiency. UCHL1 monoallelic variants should therefore be considered in any case of early-onset optic atrophy or in late-onset complex ataxic syndrome with asymptomatic optic atrophy.


Asunto(s)
Ataxia , Linaje , Fenotipo , Ubiquitina Tiolesterasa , Humanos , Ubiquitina Tiolesterasa/genética , Masculino , Femenino , Adulto , Ataxia/genética , Ataxia/fisiopatología , Persona de Mediana Edad , Mutación , Atrofia Óptica/genética
4.
Health Educ Res ; 28(1): 46-57, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22798564

RESUMEN

Research in the United States and Australia acknowledges the potential of non-government social and community service organizations (SCSOs) for reaching socially disadvantaged smokers. This study aimed to describe SCSO smoking policies and practices, and attitudes of senior staff towards smoking and cessation. It also investigated factors associated with positive tobacco control attitudes. In 2009, a cross-sectional telephone survey was undertaken of senior staff in Australian SCSOs, 149 respondents representing 93 organizations completed the survey (response rate=65%; 93/142). Most service clients (60%) remained in programs for 6 months plus, and 77% attended at least weekly. Although 93% of respondents indicated they had an organizational smoking policy, it often did not include the provision of smoking cessation support. Most respondents indicated that client smoking status was not recorded on case notes (78%). Attitudes were mostly positive towards tobacco control in SCSOs, with a mean (standard deviation) score of 8.3 (2.9) of a possible 13. The practice of assessing clients' interest in quitting was the only statistically significant factor associated with high tobacco control attitude scores. The results suggest that SCSOs are appropriate settings for reaching socially disadvantaged smokers with cessation support. Although generally receptive to tobacco control, organizations require further support to integrate smoking cessation support into usual care. In particular, education, training and support for staff to enable them to help their clients quit smoking is important.


Asunto(s)
Conocimientos, Actitudes y Práctica en Salud , Política Organizacional , Fumar , Bienestar Social , Estudios Transversales , Femenino , Humanos , Masculino , Nueva Gales del Sur , Pobreza , Prevención del Hábito de Fumar
5.
mBio ; 14(1): e0333522, 2023 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-36723077

RESUMEN

Climate change is a complex problem involving nonlinearities and feedback that operate across scales. No single discipline or way of thinking can effectively address the climate crisis. Teams of natural scientists, social scientists, engineers, economists, and policymakers must work together to understand, predict, and mitigate the rapidly accelerating impacts of climate change. Transdisciplinary approaches are urgently needed to address the role that microorganisms play in climate change. Here, we demonstrate with case studies how diverse teams and perspectives provide climate-change insight related to the range expansion of emerging fungal pathogens, technological solutions for harmful cyanobacterial blooms, and the prediction of disease-causing microorganisms and their vector populations using massive networks of monitoring stations. To serve as valuable members of a transdisciplinary climate research team, microbiologists must reach beyond the boundaries of their immediate areas of scientific expertise and engage in efforts to build open-minded teams aimed at scalable technologies and adoptable policies.


Asunto(s)
Cambio Climático , Políticas , Tecnología
6.
Clin Transl Radiat Oncol ; 41: 100649, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37346275

RESUMEN

Background and purpose: MAPKs are among the most relevant signalling pathways involved in coordinating cell responses to different stimuli. This group includes p38MAPKs, constituted by 4 different proteins with a high sequence homology: MAPK14 (p38α), MAPK11 (p38ß), MAPK12 (p38γ) and MAPK13 (p38δ). Despite their high similarity, each member shows unique expression patterns and even exclusive functions. Thus, analysing protein-specific functions of MAPK members is necessary to unequivocally uncover the roles of this signalling pathway. Here, we investigate the possible role of MAPK11 in the cell response to ionizing radiation (IR). Materials and methods: We developed MAPK11/14 knockdown through shRNA and CRISPR interference gene perturbation approaches and analysed the downstream effects on cell responses to ionizing radiation in A549, HCT-116 and MCF-7 cancer cell lines. Specifically, we assessed IR toxicity by clonogenic assays; DNA damage response activity by immunocytochemistry; apoptosis and cell cycle by flow cytometry (Annexin V and propidium iodide, respectively); DNA repair by comet assay; and senescence induction by both X-Gal staining and gene expression of senescence-associated genes by RT-qPCR. Results: Our findings demonstrate a critical role of MAPK11 in the cellular response to IR by controlling the associated senescent phenotype, and without observable effects on DNA damage response, apoptosis, cell cycle or DNA damage repair. Conclusion: Our results highlight MAPK11 as a novel mediator of the cellular response to ionizing radiation through the control exerted onto IR-associated senescence.

7.
ACG Case Rep J ; 9(12): e00934, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36600796

RESUMEN

The typical appearance of Candida esophagitis is white plaque-like membranes within the esophagus. We describe a unique case of Candida esophagitis that presented as a bulky, malignant-appearing, positron emission tomography-computed tomography-avid mass on endoscopy. Esophageal candidiasis persisted despite a standard course of antifungal medications (fluconazole 400 mg daily for 14 days), and eradication was successful only after fluconazole 800 mg daily was administered. Malignancy was excluded based on 2 separate sessions of endoscopy with multiple biopsies and finally with endoscopic full-thickness resection assisted by preresection closure with an over-the-scope clip.

8.
J Plast Reconstr Aesthet Surg ; 75(8): 2831-2870, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35780000

RESUMEN

BACKGROUND: Micropigmentation is a well-recognised option for nipple-areola complex reconstruction, as part of the breast reconstruction pathway for patients following mastectomy. As a part of delayed breast reconstruction, this treatment was put on hold during the COVID-19 pandemic. AIMS: To assess the views of patients regarding micropigmentation in response to the COVID-19 pandemic, and whether their attitudes to seeking out this part of the reconstructive journey had been altered. METHODS: A questionnaire undertaken with 53 patients between August & September 2020 attending the Micropigmentation clinic. FINDINGS: 81.1% of patients reported COVID-19 had not impacted their decision, with a similar proportion happy to proceed with the treatment at the time of questioning. CONCLUSIONS: The results highlight the importance of nipple-areola complex to our patients' reconstructive journey.


Asunto(s)
Neoplasias de la Mama , COVID-19 , Mamoplastia , Neoplasias de la Mama/cirugía , COVID-19/epidemiología , Femenino , Humanos , Mamoplastia/métodos , Mastectomía/métodos , Pezones/cirugía , Pandemias , Estudios Retrospectivos
10.
Science ; 203(4379): 410-5, 1979 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-760198

RESUMEN

The fundamentally diverse vertebrate pigment cells, melanophores, xanthophores, and iridophores, contain pigmentary organelles known, respectively, as melanosomes, pterinosomes, and reflecting platelets. Their pigments are mealanins pteridines, and purines. Mosaic pigment cells containing more than one type of organelle have been observed and mosaic organelles containing more than one type of pigment have been discovered. It is proposed that the various pigment cells are derived from a stem cell that contains a primordial organelle of endoplasmic reticular origin. This primordial organelle can differentiate into any of the known pigmentary organelles.


Asunto(s)
Cromatóforos/ultraestructura , Cresta Neural/citología , Pigmentación , Animales , Diferenciación Celular , Cromatóforos/metabolismo , Retículo Endoplásmico/metabolismo , Modelos Biológicos , Organoides/ultraestructura , Pigmentos Biológicos/metabolismo
11.
Osteoporos Int ; 19(10): 1431-44, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18324342

RESUMEN

UNLABELLED: We have developed clinical nomograms for predicting 5-year and 10-year fracture risks for any elderly man or woman. The nomograms used age and information concerning fracture history, fall history, and BMD T-score or body weight. INTRODUCTION: Although many fracture risk factors have been identified, the translation of these risk factors into a prognostic model that can be used in primary care setting has not been well realized. The present study sought to develop a nomogram that incorporates non-invasive risk factors to predict 5-year and 10-year absolute fracture risks for an individual man and woman. METHODS: The Dubbo Osteoporosis Epidemiology Study was designed as a community-based prospective study, with 1358 women and 858 men aged 60+ years as at 1989. Baseline measurements included femoral neck bone mineral density (FNBMD), prior fracture, a history of falls and body weight. Between 1989 and 2004, 426 women and 149 men had sustained a low-trauma fracture (not including morphometric vertebral fractures). Two prognostic models based on the Cox's proportional hazards analysis were considered: model I included age, BMD, prior fracture and falls; and model II included age, weight, prior fracture and fall. RESULTS: Analysis of the area under the receiver operating characteristic curve (AUC) suggested that model I (AUC = 0.75 for both sexes) performed better than model II (AUC = 0.72 for women and 0.74 for men). Using the models' estimates, we constructed various nomograms for individualizing the risk of fracture for men and women. If the 5-year risk of 10% or greater is considered "high risk", then virtually all 80-year-old men with BMD T-scores < -1.0 or 80-year-old women with T-scores < -2.0 were predicted to be in the high risk group. A 60-year-old woman's risk was considered high risk only if her BMD T-scores < or = -2.5 and with a prior fracture; however, no 60-year-old men would be in the high risk regardless of their BMD and risk profile. CONCLUSION: These data suggest that the assessment of fracture risk for an individual cannot be based on BMD alone, since there are clearly various combinations of factors that could substantially elevate an individual's risk of fracture. The nomograms presented here can be useful for individualizing the short- and intermediate-term risk of fracture and identifying high-risk individuals for intervention to reduce the burden of fracture in the general population.


Asunto(s)
Fracturas Óseas/etiología , Nomogramas , Accidentes por Caídas , Factores de Edad , Anciano , Anciano de 80 o más Años , Densidad Ósea , Métodos Epidemiológicos , Femenino , Fracturas Óseas/epidemiología , Fracturas Óseas/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Nueva Gales del Sur/epidemiología , Osteoporosis/complicaciones , Osteoporosis/epidemiología , Pronóstico , Factores Sexuales
12.
Bone ; 41(4): 690-7, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17870039

RESUMEN

UNLABELLED: This study examined the concordance in BMD measurement and longitudinal change in BMD between the GE Lunar Prodigy and GE Lunar DPX. Even though a high concordance between the densitometers was observed on a single measurement occasion, a significant discordance in longitudinal changes in BMD was observed. INTRODUCTION: Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) technology plays an important role in the diagnosis and management of osteoporosis. The present study examined the concordance in BMD measurement and longitudinal change in BMD between GE Lunar Prodigy and DPX. METHODS: BMD at the lumbar spine and femoral neck was measured in 135 individuals (47 men and 88 women, mean age 73+/-9 years) using both GE Lunar DPX and Prodigy densitometers at baseline. In this group, 56 individuals (22 men and 34 women) had repeated BMD measurements using the DPX and Prodigy during a subsequent follow-up visit (average duration: 2.2 years). RESULTS: For a single BMD measurement, the coefficient of concordance between the Prodigy and DPX was greater than 0.98 at the lumbar spine and 0.96 at the femoral neck, with the slope of linear regression being approximately 1.0. During the period of follow-up, the lumbar spine BMD decreased by -0.5% (S.D. 1.8%) when measured by DPX, which was significantly different (p=0.002) from the change measured by Prodigy (mean change=0, S.D. 2.0%). However, there was no significant difference (p=0.95) in the rate of change in femoral neck BMD measured by DPX (mean=-1.6%, S.D.=2.9) and Prodigy (mean=-1%, S.D.=1.8%). The correlation in rates of BMD change between Prodigy and DPX was 0.63 at the lumbar spine and 0.52 at the femoral neck. Simulation analysis showed that the theoretical maximum correlation in rates of BMD change between Prodigy and DPX was 0.71. CONCLUSIONS: Despite both densitometers being highly concordant in a single BMD measurement, discordance in the assessment of BMD changes between the Prodigy and DPX densitometers was observed. These findings have implications regarding the assessment of response to therapy in a multi-centre setting when different densitometers are used.


Asunto(s)
Densidad Ósea/fisiología , Densitometría/normas , Anciano , Simulación por Computador , Femenino , Humanos , Estudios Longitudinales , Masculino , Caracteres Sexuales
13.
Eat Weight Disord ; 12(2): 61-9, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17615490

RESUMEN

UNLABELLED: REASON FOR THE STUDY: Little is known about how motivation to change evolves over the course of an eating disorder. The present study compared 'stage of change' and motivation, confidence and readiness to change in two groups of patients with bulimia nervosa (BN), adolescents with a short duration of illness and adults with a long duration of illness. METHOD: Patients completed the Severity of eating disorder symptomatology scale, Hospital Anxiety and Depression Scale and measures of stage of change and motivation, readiness and confidence to change their bulimic symptomatology at pre-treatment. MAIN FINDINGS: Short- and long duration groups did not differ in illness severity, comorbidity, stage of change, motivation, readiness, and confidence to change. There were, however, some differences between groups in terms of the relationship between motivational measures, illness severity, duration and comorbidity. CONCLUSIONS: There seem to be more similarities than differences between adolescents with short duration of illness and those with well-established BN in terms of their motivation to change.


Asunto(s)
Bulimia Nerviosa/psicología , Motivación , Adolescente , Adulto , Ansiedad/complicaciones , Bulimia Nerviosa/clasificación , Depresión/complicaciones , Humanos , Aceptación de la Atención de Salud/psicología , Índice de Severidad de la Enfermedad , Factores de Tiempo
14.
Trends Microbiol ; 4(2): 77-82, 1996 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-8820572

RESUMEN

Death of HIV-infected CD4+ cells and HIV-induced death of uninfected CD4+ cells by apoptosis have been suggested to be important factors in causing the gradual progressive decline of CD4+ cells in the blood of HIV-positive patients. Recent advances in our knowledge of the dynamics of infection and the mechanism of apoptosis are reviewed with the aid of a mathematical model.


Asunto(s)
Apoptosis , Linfocitos T CD4-Positivos/virología , Infecciones por VIH/inmunología , VIH , VIH/inmunología , VIH/patogenicidad , Humanos , Cinética , Modelos Inmunológicos , Replicación Viral
15.
Biochim Biophys Acta ; 1034(1): 39-45, 1990 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-2328260

RESUMEN

We have postulated that the interaction of hyaluronic acid (HA), an extracellular matrix glycosaminoglycan, with fibrin is important during the early stages of wound healing and inflammation (J. Theor. Biol. 119:219; 1986), and have demonstrated the specific binding of 125I-labeled HA to human fibrinogen (J. Biol. Chem. 261:12 586; 1986). To determine whether HA binding is limited to human fibrinogen, we tested the ability of fibrinogens from various mammalian species to bind 125I-HA using a dot-blot assay. Increasing amounts of fibrinogen were adsorbed to nitrocellulose, and incubated with 125I-HA in the presence or absence of a 100-fold excess of nonradiolabeled HA to assess specific binding. In three independent experiments, the amount of 125I-HA bound/mg fibrinogen was determined from the slope derived by linear regression analysis of specifically bound 125I-HA versus protein concentration. A Student's t-test was performed to determine whether the slopes were statistically greater than zero. HA binding was considered statistically significant when P less than 0.05 was obtained by this analysis. Rabbit and dog fibrinogens significantly bound HA in all three trials. Baboon fibrinogen demonstrated significant HA binding in two of three trials. Pig, sheep and goat fibrinogens bound HA significantly in only one of three trials, whereas horse, rat and cow fibrinogens did not bind HA significantly at all. We conclude that fibrinogen from mammalian species other than human can specifically bind HA. The ability of fibrinogen to bind HA appears to correlate with an evolutionary divergence that separated human, baboon, dog, rabbit and rat from cow, pig, horse, goat and sheep.


Asunto(s)
Fibrinógeno/metabolismo , Ácido Hialurónico/metabolismo , Secuencia de Aminoácidos , Animales , Bovinos , Perros , Fibrina/metabolismo , Humanos , Datos de Secuencia Molecular , Papio , Conejos , Ratas , Ovinos , Especificidad de la Especie
16.
Biochim Biophys Acta ; 946(1): 66-74, 1988 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-3207732

RESUMEN

Intact isolated rat hepatocytes show a small amount of specific 125I-labeled hyaluronic acid (HA) binding. However, in the presence of digitonin, a very large increase in the specific binding of 125I-HA is observed. Chondroitin sulfate, heparin and dextran sulfate were as effective as unlabeled HA in competing for 125I-HA binding to permeabilized hepatocytes, indicating that the binding sites may have a general specificity for glycosaminoglycans. After rat hepatocytes had been homogenized in a hypotonic buffer, more than 98% of the 125I-HA binding activity could be pelleted by centrifugation at 100,000 x g for 1 h. Mild alkaline treatment of hepatocyte membranes did not release 125I-HA binding activity, suggesting that the HA binding site is an integral membrane molecule. Furthermore, trypsin treatment of deoxycholate-extracted membranes destroyed the binding activity, as assessed by a dot-blot assay. This suggests that a protein component in the membrane is necessary for 125I-HA binding activity. Rat fibrinogen could be a possible candidate for the HA binding activity because HA binds specifically to human fibrinogen (LeBoeuf et al. (1986) J. Biol. Chem. 261, 12 586). Also, fibrinogen can be found in a quasi-crystalline form in rat hepatocytes and could be pelleted with the membranes. Rat fibrinogen was not responsible for the 125I-HA binding activity, since (1) purified rat fibrinogen did not bind to 125I-HA, and (2) immunoprecipitation of rat fibrinogen from hepatocyte extracts did not decrease the 125I-HA binding of these extracts. We conclude that the internal HA binding sites are membrane- or cytoskeleton-associated proteins and are neither cytosolic proteins nor fibrinogen.


Asunto(s)
Ácido Hialurónico/metabolismo , Hígado/metabolismo , Animales , Western Blotting , Carbonatos/farmacología , Permeabilidad de la Membrana Celular , Digitonina/farmacología , Fibrinógeno/metabolismo , Masculino , Membranas/metabolismo , Ratas , Ratas Endogámicas , Tripsina/metabolismo
17.
Biochim Biophys Acta ; 1112(1): 45-51, 1992 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-1420268

RESUMEN

Atrial natriuretic peptide (ANP) is rapidly cleared and degraded in vivo. Nonguanylate-cyclase receptors (C-ANPR) and a metalloproteinase, neutral endopeptidase (EC 3.4.24.11) (NEP 24.11), are thought to be responsible for its metabolism. We investigated the mechanisms of ANP degradation by an endothelial-derived cell line, CPA47. CPA47 cells degraded 88% of 125I-ANP after 1 h at 37 degrees C as determined by HPLC. Medium preconditioned by these cells degraded 41% of the 125I-ANP, and this activity was inhibited by a divalent cation chelator, EDTA. Furthermore, a cell-surface proteolytic activity degraded 125I-ANP in the presence of EDTA when receptor-mediated endocytosis was inhibited either by low temperature (4 degrees C) or by hyperosmolarity at 37 degrees C. The metalloproteinase, NEP 24.11, is unlikely to be the cell-surface peptidase because 125I-ANP is degraded by CPA47 cells at 4 degrees C in the presence of 5 mM EDTA. These data indicate that CPA47 cells can degrade ANP by a novel divalent cation-independent cell-surface proteolytic activity.


Asunto(s)
Factor Natriurético Atrial/metabolismo , Cationes Bivalentes , Células Cultivadas , Cromatografía Líquida de Alta Presión , Ácido Edético , Humanos , Hidrólisis , Radioisótopos de Yodo , Cinética , Neprilisina/metabolismo , Concentración Osmolar , Receptores del Factor Natriurético Atrial/metabolismo
18.
Biochim Biophys Acta ; 1499(1-2): 74-84, 2000 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-11118640

RESUMEN

Glucose deprivation leads to the synthesis of an aberrantly glycosylated ('alternative') and inefficiently processed form of the insulin proreceptor in 3T3-L1 adipocytes. To further explore the effect of aberrant (rather than absent) N-linked glycosylation of the insulin receptor, we examined the relationship of processing to function. Our studies show that the alternative form of the proreceptor does not oligomerize nor does it acquire the ability to undergo insulin-sensitive autophosphorylation. This along with an interaction with the glucose-regulated stress protein GRP78/BiP implies inappropriate folding/dimerization and retention in the ER. Glucose refeeding causes the post-translational modification of the alternative form of the proreceptor to a novel 'intermediate' form which is independent of new protein synthesis. As little as 100 microM glucose (or mannose) can induce this modification. In vitro digestion of the alternative and intermediate proreceptors with SPC1/furin shows that both the alpha- and beta-subunit domains are glycosylated, albeit aberrantly. This implies that the aberrantly glycosylated proreceptor could serve as a substrate for SPC1 in a physiological setting if the receptor was able to interact with the enzyme in the appropriate compartment (i.e., the trans-Golgi network). Based on inhibitor studies, however, both the alternative and intermediate forms of the proreceptor appear to be primarily targeted to the proteasome for degradation.


Asunto(s)
Proteínas de Choque Térmico , Receptor de Insulina/metabolismo , Proteínas de Schizosaccharomyces pombe , Células 3T3 , Animales , Proteínas Portadoras/metabolismo , Compartimento Celular , Cisteína Endopeptidasas/química , Relación Dosis-Respuesta a Droga , Chaperón BiP del Retículo Endoplásmico , Glucosa/deficiencia , Glucosa/farmacología , Glicosilación , Ratones , Proteínas Quinasas Activadas por Mitógenos/química , Chaperonas Moleculares/metabolismo , Complejos Multienzimáticos/química , Fosforilación , Complejo de la Endopetidasa Proteasomal , Pliegue de Proteína , Precursores de Proteínas/biosíntesis , Precursores de Proteínas/metabolismo , Receptor de Insulina/biosíntesis , Receptor de Insulina/química , Transducción de Señal
19.
Biochim Biophys Acta ; 885(3): 317-26, 1986 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-3511974

RESUMEN

The glucose transporter in 3T3-L1 adipocytes has been identified as a polypeptide of average Mr 51000 by means of its reaction with antibodies raised against the purified human erythrocyte glucose transporter and by photolabeling with [3H]cytochalasin B. The finding that the antibodies immunoprecipitated the photolabeled polypeptide demonstrated that both methods detected the same polypeptide. The 3T3-L1 adipocyte glucose transporter has been partially purified. The main steps in the purification procedure were the preparation of salt-washed cellular membranes, Triton X-100 solubilization, and immunoaffinity chromatography on affinity-purified antibodies against the human erythrocyte transporter. A simple method of affinity purification of these antibodies, which consists of adsorption from serum onto protein-depleted erythrocyte membranes and release with acid, and an assay for the 3T3-L1 adipocyte transporter polypeptide, which employs immunoblotting, have been developed.


Asunto(s)
Tejido Adiposo/análisis , Proteínas de Transporte de Monosacáridos/aislamiento & purificación , Tejido Adiposo/citología , Animales , Línea Celular , Membrana Celular/análisis , Cromatografía de Afinidad , Insulina/farmacología , Ratones , Proteínas de Transporte de Monosacáridos/análisis , Proteínas de Transporte de Monosacáridos/inmunología
20.
Mol Endocrinol ; 13(11): 1801-10, 1999 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-10551774

RESUMEN

Recent studies have shown that methylation of the CpG island within the p16/CDKN2A gene is associated with an absence of p16 protein in human pituitary tumors. However, the effect of restoration of p16 protein expression in this tumor type has not been investigated. In the absence of an available human pituitary cell line we first assessed the suitability of the mouse corticotroph cell line AtT20 as a model system. Initial experiments showed that the p16/CDKN2A gene was not expressed, whereas a transcript for RB1 was detected as assessed by RT-PCR. Further studies showed the p16/CDKN2A gene to be homozygously deleted. The absence of p16/CDKN2A and presence of RB1, the down-stream effector of p16-mediated cell cycle arrest confirmed the suitability of the AtT20 cell line as a model system. Stable transfectants were generated in which p16/CDKN2A is regulated by an inducible promoter. The regulatory effects of p16/CDKN2A expression on cell proliferation were assessed and complemented by fluorescence-activated cell sorting (FACS) analysis of cell cycle profile. Induced expression of p16/CDKN2A resulted in a profound inhibition of cell growth and G1 arrest (80-82%). Western blot analysis showed concomitant expression of p16 protein in arrested cells and a shift in the phosphorylation status of pRB toward its hypophosphorylated form. To further confirm that expression of p16/CDKN2A mimicked its in vivo role, reversibility was assessed using alternate cycles in the presence and absence of inducer (isopropyl-1-thio-beta-D-galactopyranoside). Over three cycles the absence of induced expression of p16/CDKN2A resulted in release from G1 arrest. These results show that, in a pituitary cell line model, restoration of p16 expression is indeed sufficient to arrest cells in G1 and inhibit cell proliferation and is reversible. Thus restoration of p16 expression through novel strategies, including gene therapy or demethylating agents, may offer successful therapeutic intervention in human forms of this disease.


Asunto(s)
Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Fase G1/genética , Neoplasias Hipofisarias/genética , Neoplasias Hipofisarias/patología , Animales , Isopropil Tiogalactósido/genética , Ratones , Regiones Promotoras Genéticas , Transfección , Células Tumorales Cultivadas , Ensayo de Tumor de Célula Madre
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