RESUMEN
A new heteroleptic iridium complex demonstrated low cytotoxicity and near-infrared excitation (via two-photon absorption) for target-specific in vitro Golgi imaging in various cell lines (HeLa and A549 cells) with two-photon absorption cross section (~350 GM) in DMSO.
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Aparato de Golgi/metabolismo , Iridio/química , Sustancias Luminiscentes/química , Sustancias Luminiscentes/metabolismo , Compuestos Organometálicos/química , Compuestos Organometálicos/metabolismo , Fotones , Aparato de Golgi/efectos de los fármacos , Células HeLa , Humanos , Sustancias Luminiscentes/síntesis química , Sustancias Luminiscentes/toxicidad , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/toxicidadRESUMEN
BACKGROUND: The prevalence of childhood sleep bruxism (SB) varied from 5% to 46% among various studies. In addition to local facial and dental adverse consequences, accumulating evidence suggests that childhood SB could be associated with comorbid sleep and systemic neurobehavioral disturbances. This study attempted to investigate the prevalence and clinical correlates of SB in a large community sample. METHODS: This study was part of an ongoing epidemiologic study about sleep problems among Hong Kong Chinese children. A total of 9172 questionnaires were distributed to children of grades 1-6 from 13 randomly selected primary schools. Parents of the children were asked to complete and return the Hong Kong children sleep questionnaire, which aimed to explore the sleep problems and patterns of their children. RESULTS: Six thousand three hundred and eighty-nine questionnaires with valid answers to SB were received and the response rate was 69.7%. The mean age of the recruited children was 9.2±1.8years (50.6%, boys). The prevalence of SB with teeth grinding frequency more than thrice weekly over the past year was 5.9%. SB was more prevalent among boys with decreasing prevalence across age. SB was associated with chronic medical diseases, sleep-related breathing problem, upper respiratory infection, and other parasomnia features, especially sleep talking (OR (95%CI)=4.07 (2.33-7.11)). Children with SB were more likely noticed by their parents to be hyperactive (OR (95%CI)=1.61 (1.25-2.07)) and bad-tempered (OR (95%CI)=1.69 (1.35-2.12)) and had deterioration in their academic performance (OR (95%CI)=1.22(1.03-1.43)). CONCLUSIONS: Almost 6% of Hong Kong primary schoolchildren suffered from frequent SB. The condition was most prevalent among young boys. SB was found to be associated with a variety of medical conditions, neuropsychiatric sequelae, and comorbid sleep conditions, especially sleep talking and sleep related breathing problems. Further prospective studies will need to clarify the longitudinal course of childhood SB and its response to treatment.
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Síndromes de la Apnea del Sueño/epidemiología , Bruxismo del Sueño/epidemiología , Trastornos del Sueño-Vigilia/epidemiología , Niño , Conducta Infantil , Preescolar , Comorbilidad , Recolección de Datos , Escolaridad , Femenino , Hong Kong/epidemiología , Humanos , Masculino , Prevalencia , Habla , Encuestas y CuestionariosRESUMEN
Due to their widespread use in domestic and commercial premises, polyurethane foams, as either fragmented or bulk foam, are types of evidence commonly found at crime scenes. The traditional approach to determining the evidential value of polyurethane foam (PF) involves comparing recovered and control fragments under low and high magnification, under various lighting conditions, as well as the comparison of their respective dye spectra. As with most forms of trace evidence, chemical comparison is also desirable. In this work, two approaches to chemically comparing foam fragments were investigated, i.e. inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis of the Tin (Sn) content in different foam types; and gas chromatography-flame ionization detection (GC-FID) analysis of soluble components in PFs mobilized by dichloromethane. Seven different foam types were studied and their Sn content was found to be different. They also produced characteristic GC-FID chromatographic profiles whose compounds were identified with gas chromatography-mass spectrometry (GC-MS) analysis. This study suggests that incorporating chemical data obtained from GC-FID/GC-MS and ICP-OES into a case involving PF could be advantageous, as this will enable the forensic scientist to broaden the comparison between control and recovered fragments, and further assess the strength of the evidence. However, ICP-OES analysis is a destructive technique with a relatively short sample turnaround time, whilst GC-FID analysis is more time-consuming and non-destructive, requiring corroboration with GC-MS data. The values of these two analytical techniques in the forensic chemical characterization of PFs are discussed.
RESUMEN
Microdialysis is a novel and minimally invasive sampling technique, based on the diffusion of analytes from the interstitial compartment through a semi-permeable membrane, and enables direct assessment of tissue disposition and penetration of drugs. Variable antitumor responses may be associated with differences in tumor vascularity, capillary permeability or tumor interstitial pressure resulting in variable delivery of anticancer agents. In preparation of pharmacokinetic studies, aimed at measuring docetaxel concentrations in healthy and malignant tissues in vivo, in pre-clinical as well as clinical studies, in vitro recovery experiments were performed. In contrast to published data, the recovery experiments suggest that docetaxel has a very low recovery as a result of non-specific binding to currently available microdialysis catheters. Here we discuss our findings with docetaxel in a historical perspective and we report on our experience using polysorbate 80 to eliminate the non-specific binding and its effects on the recovery of docetaxel.
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Antineoplásicos/administración & dosificación , Antineoplásicos/farmacocinética , Microdiálisis/métodos , Taxoides/administración & dosificación , Taxoides/farmacocinética , Cromatografía Liquida , Protocolos Clínicos , Docetaxel , Humanos , Espectrometría de MasasRESUMEN
The Indo-Pacific humpback dolphin is considered threatened due to several factors including pollution in Hong Kong and the risks due to consumption of fish tainted with polychlorinated biphenyls (PCBs) and organochlorine pesticides were assessed. Six species of fish Collichthys lucida, Pseudosciaena crocea, Johnius sp., Thryssa sp., Mugil sp. and Trichiurus sp., which comprise the main prey species of humpback dolphins were collected for analyses. Risks due to total PCBs, total TEQs, PCB 118 and the pesticides were assessed with the use of toxicity reference values as the threshold reference benchmarks. The calculated risk quotients (RQs) showed that the risks associated with organochlorines were generally low. The highest RQ was associated with total TEQs suggesting that dioxin-like PCBs may pose the highest risk to the dolphins. The HCHs, total PCBs and heptachlor had comparatively high RQs and thus they should also be the priority organochlorines that would require further investigation.
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Delfines/metabolismo , Peces/metabolismo , Hidrocarburos Clorados/análisis , Contaminantes Químicos del Agua/análisis , Animales , DDT/análisis , Monitoreo del Ambiente/métodos , Extinción Biológica , Contaminación de Alimentos/análisis , Heptacloro/análisis , Hexaclorociclohexano/análisis , Hong Kong , Residuos de Plaguicidas/análisis , Bifenilos Policlorados/análisis , Conducta Predatoria , Medición de Riesgo/métodosRESUMEN
Current optical methods to collect Nomarski differential interference contrast (DIC) or phase images with a transmitted light detector (TLD) in conjunction with confocal laser scanning microscopy (CLSM) can be technically challenging and inefficient. We describe for the first time a simple method that combines the use of the commercial product QPm (Iatia, Melbourne Australia) with brightfield images collected with the TLD of a CLSM, generating DIC, phase, Zernike phase, dark-field or Hoffman modulation contrast images. The brightfield images may be collected at the same time as the confocal images. This method also allows the calculation of contrast-enhanced images from archival data. The technique described here allows for the creation of contrast-enhanced images such as DIC or phase, without compromising the intensity or quality of confocal images collected simultaneously. Provided the confocal microscope is equipped with a motorized z-drive and a TLD, no hardware or optical modifications are required. The contrast-enhanced images are calculated with software using the quantitative phase-amplitude microscopy technique (Barone-Nugent et al., 2002). This technique, being far simpler during image collection, allows the microscopist to concentrate on their confocal imaging and experimental procedures. Unlike conventional DIC, this technique may be used to calculate DIC images when cells are imaged through plastic, and without the use of expensive strain-free objective lenses.
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Microscopía Confocal/métodos , Microscopía de Interferencia/métodos , Animales , Línea Celular Tumoral , Embrión no Mamífero/anatomía & histología , Fibroblastos , Humanos , Leishmania mexicana , Mastocitos , Ratones , Células 3T3 NIH , Ratas , Pez Cebra/embriologíaRESUMEN
In order to assess the potential risks associated with consumption of contaminated prey items to the Indo-Pacific Humpback dolphin (Sousa chinensis), fish species (Collichthys lucida, Pseudosciaena crocea, Johnius sp., Thryssa sp., Mugil sp. and Trichiurus sp.) representing the main food items of the dolphin were collected from the northwestern waters of Hong Kong, including the Sha Chau and Lung Kwu Chau Marine Park, which form the main habitat of the dolphin in Hong Kong. Within these waters, there are several potential sources of pollution including significant inputs from the Pearl River catchment, several major sewage outfalls and a series of mud pits that receive contaminated dredged sediments. Concentrations of thirteen trace elements (Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mn, Ni, Se, V, and Zn) in the fish tissue were analyzed by inductively coupled plasma mass spectrometer (ICP-MS). An assessment of the risks of adverse effects on the dolphin due to consumption of tainted fish was undertaken using two toxic reference benchmarks, namely the reference dose (RfD) and toxicity reference value (TRV). The risk quotient (RQ) calculated for each element showed that the risks from consumption of fish were generally low and within safe limits. The risks associated with arsenic, cadmium and mercury were, however, elevated. The highest calculated RQ was associated with total arsenic; however, the majority of arsenic in marine organisms tends to be in the non-toxic organic form, and the actual risk to the dolphin due to this metalloid is likely to be lower.
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Arsénico/análisis , Dieta , Delfines/metabolismo , Contaminantes Ambientales/análisis , Peces/metabolismo , Cadena Alimentaria , Metales Pesados/análisis , Animales , Arsénico/toxicidad , Monitoreo del Ambiente/estadística & datos numéricos , Contaminantes Ambientales/toxicidad , Hong Kong , Espectrometría de Masas , Metales Pesados/toxicidad , Valores de Referencia , Medición de Riesgo , Agua de MarRESUMEN
Polyps of the gall bladder are uncommon conditions in children. We present a case report of a 14-year-old girl who had calculous cholecystitis and an adenomatous hyperplastic polyp of the gall bladder. She was treated by laparoscopic cholecystectomy.
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Pólipos Adenomatosos/patología , Colelitiasis/patología , Neoplasias de la Vesícula Biliar/patología , Pólipos Adenomatosos/cirugía , Adolescente , Colecistectomía Laparoscópica , Colelitiasis/cirugía , Femenino , Neoplasias de la Vesícula Biliar/cirugía , Humanos , Hiperplasia/patología , Hiperplasia/cirugíaRESUMEN
Eggs of two Ardeid species, the Little Egret (Egretta garzetta) and the Black-crowned Night Heron (Nycticorax nycticorax), were collected from two egretries located in the New Territories of Hong Kong with one located near the internationally acclaimed wetland reserve, the Mai Po Marshes, and the other in a remote site (A Chau). The eggs were analysed for organochlorine (OC) compounds including the DDTs, PCBs, hexachlorocyclohexanes (HCHs) and the chlordanes (CHLs). All of the OCs under investigation were detected in the eggs of both species with significantly higher levels in the Little Egret (DDTs, 560-2200; PCBs, 270-1700; CHLs, 81-470 ng g(-1) wet weight) than the Night Heron (DDTs, 210-1200; PCBs, 85-600; CHLs 59-75 ng g(-1) wet weight). The DDTs consisted mainly of DDE with levels ranging from 85% to 95% of the total. The HCHs were at about the same levels in both species (8.4-30 ng g(-1) wet weight). All of the OCs had linear concentration probability distributions on a log-normal basis which were used to evaluate exposure associated with these compounds as part of a probabilistic risk analysis. A linear dose/response relationship for the percentage reduction in the survival of young associated with DDE in eggs was developed. This probabilistic relationship was used to establish the threshold level (1000 ng g(-1) wet weight) at which there was a significant level of reduction in the survival of young above zero and the variability in DDE concentrations at this effect level. Using a threshold level of 1000 ng g(-1), the calculated Risk Quotient (RQ) had a 12.4% probability of RQ exceeding unity with the Night Heron, and 40.9% with the Little Egret. These results indicate that the DDTs in eggs would be expected to be associated with adverse effects on the survival of young of both species, particularly the Little Egret.
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Aves , Hidrocarburos Clorados , Insecticidas/efectos adversos , Reproducción , Animales , Animales Recién Nacidos , Huevos , Exposición a Riesgos Ambientales , Femenino , Hong Kong , Insecticidas/análisis , Insecticidas/farmacocinética , Masculino , Medición de Riesgo , SobrevidaRESUMEN
Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/ F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.
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Benzofuranos/análisis , Contaminantes Ambientales/análisis , Sedimentos Geológicos/química , Dibenzodioxinas Policloradas/análogos & derivados , Dibenzodioxinas Policloradas/análisis , Contaminantes del Suelo/análisis , Dibenzofuranos Policlorados , Monitoreo del Ambiente , Hong Kong , Valores de ReferenciaRESUMEN
OBJECTIVE: To investigate the effectiveness of misoprostol given vaginally for cervical priming before hysteroscopy in postmenopausal women. DESIGN: Double-blind randomised controlled study. SETTING: Regional hospital, Hong Kong. PARTICIPANTS: One hundred women with postmenopausal bleeding scheduled for hysteroscopy from October 1998 to September 2001 were randomly assigned to receive either misoprostol or placebo vaginally before the operation. MAIN OUTCOME MEASURES: The number of women requiring cervical dilatation, outcome of hysteroscopy and side effects of the medication were assessed. RESULTS: Forty-eight women receiving misoprostol and 48 women receiving placebo were compared. The mean degree of endocervical diameter estimated by Hegar's dilator was similar between the treatment group and the control group. A similar number of women in the treatment group and the control group required cervical dilatation. The operative times for both groups were similar. The incidence of side effects was comparable in both groups. The most common side effects for misoprostol were febrile episodes and diarrhoea. There was no cervical tear nor uterine perforation encountered in both groups. The mean duration of hospital stay in both groups were similar. Subanalysis of results were similar in women receiving vaginal medication at least five hours before the operation. CONCLUSION: Vaginal misoprostol was not shown to reduce the need for cervical dilatation in postmenopausal women. It cannot convert diagnostic hysteroscopy from a hospital procedure into an office one in postmenopausal women with tight cervical os.
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Cuello del Útero/efectos de los fármacos , Histeroscopía/métodos , Misoprostol/administración & dosificación , Oxitócicos/administración & dosificación , Administración Intravaginal , Anciano , Dilatación/métodos , Método Doble Ciego , Femenino , Humanos , Persona de Mediana Edad , Misoprostol/efectos adversos , Oxitócicos/efectos adversos , Posmenopausia/fisiologíaRESUMEN
The feathers of two Ardeid species, the Little Egret (Egretta garzetta) and the Black-crowned Night Heron (Nycticorax nycticorax) were collected from six egretries and two egretries respectively, located in different areas in the New Territories of Hong Kong, including the Mai Po Marshes (within a Ramsar site). These feathers were digested and concentrations (microg/g dry weight) of copper (4.6-19.4), iron (8.1-641.3), manganese (0.4-19.4), zinc (51.3-183.5), lead (0.1-5.1), cadmium (0.01-0.15), chromium (0.06-1.7) and mercury (0.0-7.1) were determined by ICP-AES, ICP-MS and CVAAS. The levels of manganese, mercury and lead found were equal to or less than the concentrations found in previous investigations, reflecting a slight downward trend most apparent with lead. As a general rule, the levels of lead and mercury were higher in the egretries close to the polluted Deep Bay. A probabilistic risk assessment of the possible adverse effects on the breeding success of the Little Egret was carried out with respect to mercury, lead and cadmium. It was concluded that mercury (0.5-7.1 microg/g dry weight feathers) probably has had adverse effects at the Au Tau egretry of the Little Egrets, but there was no evidence of adverse effects at other egretries. The probabilistic analysis also indicated a low likelihood of adverse effects of mercury on the breeding of the Black-crowned Night Herons at A Chau (0.3-1.2 microg/g) and Mai Po Village (0.0-1.4 microg/g). The evidence for the effects of lead and cadmium was limited but suggested there may possibly be adverse effects with lead but not cadmium.
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Aves , Metales Pesados/efectos adversos , Reproducción , Contaminantes del Agua/efectos adversos , Animales , Plumas/química , Femenino , Hong Kong , Masculino , Metales Pesados/farmacocinética , Medición de Riesgo , Contaminantes del Agua/farmacocinéticaRESUMEN
Parathyroid hormone-related protein is responsible for hypercalcemia induced by various tumors. The similarity of its N-terminus to that of parathyroid hormone enables parathyroid hormone-related protein to share parathyroid hormone's signaling properties, but the rest of the molecule possesses distinct functions including a role in the nucleus/nucleolus in reducing apoptosis and enhancing cell proliferation. We have previously shown that parathyroid hormone-related protein nuclear import is mediated by importin beta1. Here we use fluorescence recovery after photobleaching for the first time to show that, in living cells, parathyroid hormone-related protein is exported from the nucleus in a leptomycin B-sensitive manner, implicating CRM1 as the parathyroid hormone-related protein nuclear export receptor. Leptomycin B treatment significantly reduced the rate of nuclear export 4 -10-fold, thereby increasing parathyroid hormone-related protein concentration in the nucleus/nucleolus about 2-fold. Intriguingly, this also led to a 2-fold reduced nuclear import rate. Inhibiting the nuclear export of a protein able to shuttle between nucleus and cytoplasm through distinct receptors thus can also affect nuclear import, indicating that the subcellular localization of a protein containing distinct nuclear import and export signals is the product of an integrated system. Although there have been several recent studies examining the dynamics of intranuclear transport using fluorescence recovery after photobleaching, this represents, to our knowledge, the first use of the technique to examine the kinetics of nucleocytoplasmic flux in living cells.
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Núcleo Celular/efectos de los fármacos , Citoplasma/efectos de los fármacos , Ácidos Grasos Insaturados/farmacología , Proteínas/metabolismo , Animales , Células COS , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Humanos , Proteína Relacionada con la Hormona Paratiroidea , Transporte de Proteínas , Células Tumorales CultivadasRESUMEN
A solid-phase microextraction (SPME) method was applied to study microcystin (MC) profiles in a natural Microcystis sp. bloom in a freshwater pond in Guangzhou, China. Three dominant MC variants, namely MC-LR, MC-YR, and MC-RR, were quantified. Simultaneous study of their total, extracellular, and intracellular profiles was made possible using SPME coupled to high-performance liquid chromatography. The total and intracellular concentrations of MC-LR in the bloom were 8.67 x 10(-2) microg/ ml and 1.93 mg/g, respectively. The corresponding concentrations of MC-YR were 1.20 x 10(-3) microg/ml and 0.06 mg/g, respectively, and those of MC-RR were 5.57 x 10(-2) microg/ml and 1.49 mg/g, respectively. Only MC-LR was detectable in the extracellular phase (1.49 x 10(-2) microg/ml) of the bloom, and its concentration was 14% of the intracellular content. Mass balance consideration revealed that only 71.1% of total MC-LR, 36.0% of total MC-YR, and 67.4% of total MC-RR within the cyanobacterial cells were released into the aqueous phase immediately after cell lysis.
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Cianobacterias , Eutrofización , Péptidos Cíclicos/análisis , Cromatografía Líquida de Alta Presión , Monitoreo del Ambiente/métodos , Líquido Intracelular/química , Toxinas Marinas , MicrocistinasRESUMEN
Specific cellular stresses, including hyperosmotic stress, caused a dramatic but reversible cytoplasmic accumulation of the otherwise nuclear 45-kDa variant of the protein-tyrosine phosphatase TCPTP (TC45). In the cytoplasm, TC45 dephosphorylated the epidermal growth factor receptor and down-regulated the hyperosmotic stress-induced activation of the c-Jun N-terminal kinase. The hyperosmotic stress-induced nuclear exit of TC45 was not inhibited by leptomycin B, indicating that TC45 nuclear exit was independent of the exportin CRM-1. Moreover, hyperosmotic stress did not induce the cytoplasmic accumulation of a green fluorescent protein-TC45 fusion protein that was too large to diffuse across the nuclear pore. Our results indicate that TC45 nuclear exit may occur by passive diffusion and that cellular stress may induce the cytoplasmic accumulation of TC45 by inhibiting nuclear import. Neither p42(Erk2) nor the stress-activated c-Jun N-terminal kinase or p38 mediated the stress-induced redistribution of TC45. We found that only those stresses that stimulated the metabolic stress-sensing enzyme AMP-activated protein kinase (AMPK) induced the redistribution of TC45. In addition, specific pharmacological activation of the AMPK was sufficient to cause the accumulation of TC45 in the cytoplasm. Our studies indicate that specific stress-activated signaling pathways that involve the AMPK can alter the nucleocytoplasmic distribution of TC45 and thus regulate TC45 function in vivo.
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Núcleo Celular/metabolismo , Proteínas Tirosina Fosfatasas/metabolismo , Receptores Citoplasmáticos y Nucleares , Células 3T3 , Proteínas Quinasas Activadas por AMP , Transporte Activo de Núcleo Celular/fisiología , Animales , Células COS , Tamaño de la Célula , Células Cultivadas , Citoplasma/enzimología , Citosol/metabolismo , Difusión , Activación Enzimática , Receptores ErbB/metabolismo , Células HeLa , Humanos , Carioferinas/metabolismo , Ratones , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Complejos Multienzimáticos/metabolismo , Presión Osmótica , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 2 , Transducción de Señal/fisiología , Fracciones Subcelulares , Proteína Exportina 1RESUMEN
Produced by various types of solid tumors, parathyroid hormone-related protein (PTHrP) is the causative agent of humoral hypercalcemia of malignancy. The similarity of PTHrP's amino-terminus to that of parathyroid hormone enables it to share some of the latter's signalling properties, but its carboxy-terminus confers distinct functions including a role in the nucleus/nucleolus in reducing apoptosis and enhancing cell proliferation. PTHrP nuclear import occurs via a novel importin beta1-mediated pathway. The present study uses several different direct binding assays to map the interaction of PTHrP with importin beta using a series of alanine mutated PTHrP peptides and truncated human importin beta1 derivatives. Our results indicate that PTHrP amino acids 83-93 (KTPGKKKKGK) are absolutely essential for importin beta1 recognition with residues 71-82 (TNKVETYKEQPL) additionally required for high affinity binding; residues 380-643 of importin beta1 are required for the interaction. Binding of importin beta1 to PTHrP is reduced in the presence of the GTP-bound but not GDP-bound form of the guanine nucleotide binding protein Ran, consistent with the idea that RanGTP binding to importin beta is involved in the release of PTHrP into the nucleus following translocation across the nuclear envelope. This study represents the first detailed examination of a modular, non-arginine-rich importin beta1-recognized nuclear targeting signal.
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Proteínas Nucleares/metabolismo , Proteínas/metabolismo , Transporte Activo de Núcleo Celular , Secuencia de Aminoácidos , Animales , Sitios de Unión/genética , Línea Celular , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Técnicas In Vitro , Carioferinas , Cinética , Datos de Secuencia Molecular , Mutación , Señales de Localización Nuclear/genética , Proteínas Nucleares/química , Proteínas Nucleares/genética , Proteína Relacionada con la Hormona Paratiroidea , Unión Proteica , Proteínas/química , Proteínas/genética , Conejos , Ratas , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Eliminación de Secuencia , Proteína de Unión al GTP ran/metabolismoRESUMEN
Although the specific role of transcription factors (TFs) is nuclear, surprisingly little is known in quantitative terms regarding the pathways by which TFs localize in the nucleus. In this study, we use direct binding assays, native gel electrophoresis, and fluorescence polarization measurements to show for the first time that the cAMP-response element binding protein (CREB) and related AP-1 and jun and fos constituents are recognized by importin beta1 (Impbeta) with nanomolar affinity. We reconstitute the nuclear import of these TFs in vitro, demonstrating dependence on cytosolic factors, and show that this is due to the requirement for Impbeta, since antibodies to Impbeta, but not to importin alpha (Impalpha), inhibit nuclear accumulation significantly. We show that Impbeta is necessary and sufficient for docking of CREB at the nuclear envelope; that Ran is essential for CREB nuclear import is demonstrated by the reduction of nuclear accumulation effected by RanGTPgammaS but not RanGDP, and by dissociation of the Impbeta-CREB-GFP complex by RanGTPgammaS but not RanGDP as demonstrated using fluorescence polarization assays. The results support the existence of an Impbeta1- and Ran-mediated nuclear import pathway for CREB and related constitutively nuclear TFs, which is Impalpha-independent and thus distinct from import pathways utilized by inducible TFs.
Asunto(s)
Núcleo Celular/metabolismo , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Proteínas Nucleares/fisiología , Factor de Transcripción AP-1/metabolismo , Proteína de Unión al GTP ran/fisiología , Transporte Activo de Núcleo Celular/genética , Animales , Núcleo Celular/genética , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/genética , Citosol/fisiología , Carioferinas , Ratones , Poro Nuclear/genética , Poro Nuclear/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Unión Proteica/genética , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , Proteínas Proto-Oncogénicas c-jun/genética , Proteínas Proto-Oncogénicas c-jun/metabolismo , Ratas , Factor de Transcripción AP-1/genéticaRESUMEN
The use of radiation therapy to inhibit vascular proliferative diseases has produced encouraging results in several clinical trials. However, little is known about the possible side effects of radiation on vascular responsiveness. Our goal was to study the in vitro vascular responses of the rabbit aorta to various agonists immediately after several regimens of radiation therapy administered at doses prescribed in clinical protocols and at two different dose rates. High-dose-rate radiation was administered either by brachytherapy, using a gamma source, iridium 192, or an external electron beam producing beta radiation. Low-dose-rate radiation was administered by brachytherapy using a liquid-filled balloon with the beta emitter 32P. Vascular reactivity after the various regimens of irradiation was determined using the organ bath pharmacology assay. Various agonists were applied to the rabbit aorta to produce full cumulative concentration-response curves. Radiation, administered using an external electron beam, did not alter endothelium-dependent relaxation of the aorta induced by acetylcholine. However, the use of a catheter-based system to deliver radiation disrupted the endothelial cell lining of the vessel, causing a lack of relaxation by acetylcholine. Therefore, to compare all modalities of radiation therapy on vascular responsiveness, the agonists used in this study are known to act directly on the smooth muscle. Radiation therapy had no effect on the contractile responses induced by the following agonists: phenylephrine and potassium chloride. Vascular dilatation induced by nitroglycerin, a nitric oxide donor, was unaffected by radiation therapy. The contractile response induced by des-Arg9-bradykinin, a kinin B1 receptor agonist, was significantly increased twofold to threefold by all types of irradiation under study. This enhanced response is attributable to an increase of mRNA levels coding for this receptor. In all cases, radiation therapy did not alter the effective concentration producing 50% of maximal responsiveness (EC50) and did not reduce the vascular responsiveness induced by agonists. Taken together, we conclude that radiation therapy does not hinder endothelium-independent vascular responsiveness and increases the kinin B1 receptor-mediated vasoconstriction.
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Aorta/efectos de la radiación , Bradiquinina/análogos & derivados , Bradiquinina/farmacología , Contracción Muscular/efectos de los fármacos , Fenilefrina/farmacología , Acetilcolina/farmacología , Animales , Aorta/fisiología , Partículas beta , Rayos gamma , Técnicas In Vitro , Contracción Muscular/efectos de la radiación , Nitroglicerina/farmacología , Cloruro de Potasio/farmacología , Conejos , Dosificación Radioterapéutica , Receptor de Bradiquinina B1 , Receptores de Bradiquinina/genética , Receptores de Bradiquinina/metabolismo , Vasoconstrictores/farmacología , Vasodilatadores/farmacologíaRESUMEN
Predatory waterbirds, such as ardeids, are susceptible to bioaccumulation of pollutants through the ingestion of contaminated food sources. High body burdens of contaminants, including PCBs, PAHs, cadmium, mercury, lead, copper, zinc and arsenic have been detected in many bird species worldwide. There is a paucity of literature, however, linking contaminant body burden and effects on reproductive success in waterbirds. This review is a synthesis of pertinent literature on this topic, with specific reference to contaminant residues in various tissue types, relationship between body burden and reproductive success, and the use of biomarkers to predict more serious adverse affects. The impetus for this review was the development of a conservation strategy and management plan (commissioned by the Agriculture, Fisheries and Conservation Department of Hong Kong Special Administrative Region (SAR)) for an important wetland in Hong Kong that supports many threatened waterbirds, including ardeids.