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1.
Xenotransplantation ; 28(2): e12663, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33230864

RESUMEN

BACKGROUND: Genetically modified pigs (GMP) have been developed to alleviate the shortage of donors in human islet transplantation and rejection. In this study, we characterized and compared the islets from GalTKO, GalTKO/hCD46, GalTKO/hCD46/hCD39, and wild-type (WT) neonatal pigs. METHODS: Islets were isolated from GMP and WT pig pancreases that have been packaged with ice pack for at least 24 hours. The difference in gene expression and function of islets were evaluated by microarray analysis and transplantation of islets under the kidney capsule of streptozotocin-induced diabetic immune-deficient mice, respectively. Blood glucose levels of these mice were monitored weekly post-transplantation for >100 days, and islet grafts were collected and evaluated for the presence of endocrine cells. RESULTS: The genes involved in extracellular components, cell adhesion, glucose metabolism, and inflammatory response are differentially expressed between GMP and WT pig islets. Variation in the ability of pig islets in correcting the diabetic state of the mouse recipients appears to be dependent on the pig donor. In addition, prolonged cold ischemia time had a negative effect on the transplant outcome. All normoglycemic mice were able to respond well to glucose challenge despite the initial differences in the ability of islet transplants to reverse their diabetic state. Islet xenografts of normoglycemic mice contained abundant insulin- and glucagon-positive cells. CONCLUSION: The effect of GMP and WT neonatal pig islet transplants on hyperglycemia in mice appears to be dependent on the pig donor, and prolonged cold ischemia time negatively affects the neonatal pig islet transplant outcome.


Asunto(s)
Diabetes Mellitus Experimental , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Animales , Isquemia Fría , Ratones , Páncreas , Trasplante Heterólogo
2.
Int Braz J Urol ; 45(3): 541-548, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31038863

RESUMEN

OBJECTIVES: To investigate whether Glasgow Prognostic Score has prognostic significance in patients with upper urinary urothelial carcinoma. PATIENTS AND METHODS: We retrospectively reviewed the clinical records of 74 patients with upper urinary urothelial carcinoma. We set the cut-off value for C-reactive protein as 1.0mg/dL, and 3.5mg/dL for albumin as Glasgow Prognostic Score. Their blood data including albumin and C-reactive protein for Glasgow Prognostic Score and cytokeratin 19 fragment 21-1 as a tumor marker were measured before starting treatment. The patients were stratified into three groups with Glasgow Prognostic Score: The Group-1, albumin ≥3.5g/dL and C-reactive protein < 1.0mg/dL; Group-2, albumin < 3.5g/dL or C-reactive protein ≥1.0mg/dL; Group-3, albumin < 3.5g/dL and C-reactive protein ≥1.0mg/dL. RESULTS: The median follow-up for all patients was 26.9 months (range: 10.9-91.1 months), during which 37 (50%) patients died. There was a signifi cant difference in the estimated survival rate among the 3 groups stratified by Glasgow Prognostic Score. The estimated survival rate in the Group-1 was significantly higher than those in Groups 2 and 3. In the univariate analysis C-reactive protein, serum cytokeratin 19 fragment 21-1 and Glasgow Prognostic Score were significant predictors of overall survival. On the multivariate analysis, serum cytokeratin 19 fragment 21-1 and Glasgow Prognostic Score were independently associated with shorter overall survival. CONCLUSION: Our review suggests Glasgow Prognostic Score may play as a prognostic predictor for upper urinary urothelial carcinoma.


Asunto(s)
Carcinoma/sangre , Neoplasias Urológicas/sangre , Anciano , Anciano de 80 o más Años , Antígenos de Neoplasias/sangre , Biomarcadores de Tumor/sangre , Proteína C-Reactiva/análisis , Carcinoma/patología , Femenino , Humanos , Estimación de Kaplan-Meier , Queratina-19/sangre , Masculino , Persona de Mediana Edad , Pronóstico , Modelos de Riesgos Proporcionales , Valores de Referencia , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y Especificidad , Albúmina Sérica/análisis , Estadísticas no Paramétricas , Neoplasias Urológicas/patología , Urotelio/patología
3.
Biochim Biophys Acta ; 1848(1 Pt A): 145-50, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25312694

RESUMEN

KcsA is a pH-dependent potassium channel that is activated at acidic pH. The channel undergoes global conformational changes upon activation. We hypothesized that the open-close conformational changes of the transmem brane region could promote the flip-flop of phosphoiipids. Based on this hypothesis, we measured the flip-flop ofNBD-labeled phospholipids in KcsA-incorporated proteoliposomes. Both flip and flop rates of ~NBD-PC were significantly enhanced in the presence of KcsA and were several times higher at pH 4.0 than at pH 7.4, suggesting that KcsA promotes the phospholipid flip in a conformation-dependent manner. Phospholipids were nonselectively flipped with respect to the glycerophospholipid structure. In the active state of KcsA channel,tetrabutylammonium locks the channel in the open conformation at acidic pH; however, it did not alter the fliprate of CGNBD-PC. Thus, the open-close transition of the transmembrane region did not affect the flip-flop of phospholipids. In addition, the KcsA mutant that lacked anN-terminal amphipathic helix (MO-helix) was found to show reduced ability to fl ip C6NBD-phospholipids at acidic pH. The closed conformation is stabilized in the absence of MO-heli x, and thus the attenuated flip could be explained by the reduced prevalence of the open conformation.These results suggest that the open conformation of KcsA can disturb the bilayer integrity and facilitate the flip-flop of phospholipids.


Asunto(s)
Proteínas Bacterianas/química , Membrana Dobles de Lípidos/química , Fosfolípidos/química , Canales de Potasio/química , 4-Cloro-7-nitrobenzofurazano/análogos & derivados , 4-Cloro-7-nitrobenzofurazano/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Colesterol/química , Colesterol/metabolismo , Concentración de Iones de Hidrógeno , Membrana Dobles de Lípidos/metabolismo , Modelos Moleculares , Mutación , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Fosfolípidos/metabolismo , Canales de Potasio/genética , Canales de Potasio/metabolismo , Unión Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Compuestos de Amonio Cuaternario/química
4.
Phys Chem Chem Phys ; 17(33): 21104-11, 2015 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-26147491

RESUMEN

Surface-enhanced IR absorption spectroscopy (SEIRAS) is a powerful tool for studying the structure of molecules adsorbed on an electrode surface (ATR-SEIRA). Coupled with an electrochemical system, structural changes induced by changes in the electric field can be detected. All the membrane proteins are subjected to the effect of membrane electric field, but conformational changes at different membrane potentials and their functional relevance have not been studied extensively except for channel proteins. In this contribution, background information of potential-dependent functional and structural changes of a prototypical channel, the KcsA channel, is summarized, and SEIRAS applied to the KcsA channel under the application of the potential is shown. The potassium channels allow K(+) to permeate selectively through the structural part called the selectivity filter, in which dehydrated K(+) ions interact with backbone carbonyls. In the absence of K(+), the selectivity filter undergoes conformational changes to the non-conductive collapsed conformation. To apply the electric field, the KcsA channels were fixed on the gold surface in either upside or reverse orientation. The SEIRA spectrum in K(+) or Na(+) solution revealed both backbone structural changes and local changes in the OCO-carboxylate groups. Upon application of the negative electric field, the spectrum of OCO was enhanced only in the K(+) solution. These results indicate that the negative electric field accumulates local K(+) concentration, which turned the collapsed filter to the conductive conformation. ATR-SEIRA serves as an unprecedented experimental system for examining membrane proteins under an electric field.


Asunto(s)
Canales de Potasio/química , Espectrofotometría Infrarroja , Electricidad , Bloqueadores de los Canales de Potasio/química , Bloqueadores de los Canales de Potasio/metabolismo , Canales de Potasio/metabolismo , Estructura Terciaria de Proteína , Compuestos de Amonio Cuaternario/química , Compuestos de Amonio Cuaternario/metabolismo
5.
Surg Endosc ; 29(4): 851-5, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25060685

RESUMEN

BACKGROUND: Rectovesical fistula is a rare complication following prostatectomy, associated with significant symptoms such as urinary drainage from anus or faecaluria. While several surgical procedures have been described to treat this condition, none of them has been accepted as the universal standard. Transanal endoscopic microsurgery (TEM) is a well-established endoluminal procedure for local excision of rectal tumors. But its application to the repair of rectovesical fistula has been almost unknown. METHODS: We performed TEM as a surgical repair for refractory rectovesical fistula developing after radical prostatectomy in 10 patients. Under the magnified three-dimensional view, through the stereoscope, the fistula and the surrounding rectal mucosa were precisely resected. The defect and the muscle layer of the rectum were closed by hand-sew technique in four layers. RESULTS: Fistula was completely closed in 7 patients, who eventually underwent enterostomy closure, while in the other 3 patients the fistula recurred. In the three recurrent cases, the fistula was associated with wide, tough scar tissue due to previous irradiation, HIFU, or repeated surgical repair attempts. CONCLUSIONS: Rectovesical fistulas associated with wide, tough scar tissue due to multi-time attempt of surgical repair or any type of energy ablation should not be indicated for repair by TEM. However, for simple fistulas without tough, fibrotic surroundings, TEM can be indicated as a minimally invasive surgical option with very low morbidity, without any incision in healthy tissue for approach.


Asunto(s)
Microcirugia/métodos , Cirugía Endoscópica por Orificios Naturales/métodos , Complicaciones Posoperatorias/cirugía , Prostatectomía , Fístula Rectal/cirugía , Recto/cirugía , Fístula de la Vejiga Urinaria/cirugía , Anciano , Canal Anal , Humanos , Masculino , Persona de Mediana Edad , Prostatectomía/métodos , Fístula Rectal/etiología , Resultado del Tratamiento , Fístula de la Vejiga Urinaria/etiología
7.
Pediatr Surg Int ; 31(10): 987-90, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26276429

RESUMEN

There is a risk of developing a fatal trachea-innominate artery fistula following laryngotracheal separation for the prevention of intractable aspiration pneumonia. We developed a novel technique of surgical closure of the larynx to avoid this complication and provide long-term cannula-free care.


Asunto(s)
Fístula/prevención & control , Laringe/cirugía , Neumonía por Aspiración/complicaciones , Enfermedades de la Tráquea/prevención & control , Niño , Humanos , Masculino
8.
Afr J Paediatr Surg ; 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38426534

RESUMEN

BACKGROUND: To predict native liver survival (NLS) after Kasai portoenterostomy (KP) for biliary atresia (BA) using pre-operative clinical data. METHODS: Pre-operative data were collected from 29 patients with BA who underwent KP at our department between 1989 and 2017 and were analysed including serum albumin, bilirubin, prothrombin time-international normalised ratio, body height, body weight, age at KP, paediatric end-stage liver disease score calculated using the pre-operative data and the period of NLS. RESULTS: The 10-year NLS rate of all patients was 51%. A multivariate analysis revealed that among all factors, the pre-KP serum albumin level was the only independent predictor of NLS (P = 0.04, hazard ratio = 0.269, 95% confidence interval = 0.077-0.934). The area under the receiver operating characteristic curve for NLS, determined using pre-KP serum albumin was 0.760 and 3.75 mg/dl was selected as the cut-off value. There was a significant difference in NLS between patients with high (≥3.8 mg/dl) and low (≤3.7 mg/dl) pre-KP serum albumin (90.0% vs. 31.5%, P < 0.01). CONCLUSIONS: Decreased pre-KP serum albumin may reflect not only functional impairment of the liver, but also the inflammatory process, which is hypothesized to occur during its advancement. The pre-KP serum albumin level may be a good prognostic factor for NLS in post-KP BA patients.

9.
Plant Cell Physiol ; 54(7): 1027-40, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23737502

RESUMEN

Water-soluble orange carotenoid proteins (OCPs) that bind 3'-hydroxyechinenone are found in cyanobacteria, and are thought to play a key role in photoprotection. The distribution of OCPs in eukaryotes remains largely unknown. In this study, we identified a novel OCP that predominantly binds astaxanthin from a eukaryotic microalga, strain Ki-4, isolated from a dry surface of heated asphalt in midsummer. A purified astaxanthin-binding OCP, named AstaP, shows high solubility in water with an absorption peak at 484 nm, and possesses a heat-stable activity that quenches singlet oxygen. The deduced amino acid sequence of AstaP comprises an N-terminal hydrophobic signal peptide, fasciclin domains found in secreted and cell surface proteins, and N-linked glycosylation sites, the first example of a carotenoprotein among fasciclin family proteins. AstaP homologs of unknown function are distributed mainly in organisms from the hydrosphere, such as marine bacteria, cyanobacteria, sea anemone and eukaryotic microalgae; however, AstaP exhibits a unique extraordinarily high isoelectric point (pI) value among homologs. The gene encoding AstaP, as well as the AstaP peptide, is expressed abundantly under conditions of dehydration and salt stress in conjunction with high light exposure. As a unique aqueous carotenoprotein, AstaP will provide a novel function of OCPs in protection against extreme photooxidative stresses.


Asunto(s)
Proteínas Algáceas/metabolismo , Chlorophyta/metabolismo , Hidrocarburos , Microalgas/metabolismo , Proteínas Algáceas/clasificación , Proteínas Algáceas/genética , Secuencia de Aminoácidos , Northern Blotting , Carotenoides/metabolismo , Chlorophyta/citología , Chlorophyta/ultraestructura , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Células Eucariotas/metabolismo , Expresión Génica/efectos de los fármacos , Expresión Génica/efectos de la radiación , Luz , Espectrometría de Masas/métodos , Microalgas/citología , Microalgas/aislamiento & purificación , Microscopía Electrónica de Rastreo , Datos de Secuencia Molecular , Estrés Oxidativo/efectos de la radiación , Filogenia , Unión Proteica , Estaciones del Año , Homología de Secuencia de Aminoácido , Cloruro de Sodio/farmacología , Solubilidad , Agua/metabolismo , Xantófilas/metabolismo
10.
J Zoo Wildl Med ; 43(3): 632-5, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23082531

RESUMEN

A necropsy was performed on an adult European lynx, Lynx lynx (Linnaeus, 1758), held in captivity until its death, to determine level of parasitism. Examination of the eyes revealed the oriental eyeworm, Thelazia callipaeda, in the conjunctival sac and the third eyelid of both eyes. The species was confirmed by location and morphology. Intact worms were fixed, mounted, and identified. Examination of the alimentary tract revealed the common ascaroid nematode, Toxocara cati. Species was confirmed by the arrow-like anterior end. One hundred and forty-one adult worms were collected. The presence of these nematodes indicated the importance of eliminating the contact of zoo animals with Amiota spp. vectors and to prevent contamination with the infective T. cati eggs.


Asunto(s)
Lynx , Infecciones por Spirurida/veterinaria , Thelazioidea/aislamiento & purificación , Toxocara/aislamiento & purificación , Toxocariasis/parasitología , Animales , Animales de Zoológico , Resultado Fatal , Japón/epidemiología , Masculino , Neumonía/mortalidad , Neumonía/veterinaria , Infecciones por Spirurida/epidemiología , Infecciones por Spirurida/parasitología , Toxocara/clasificación , Toxocariasis/epidemiología
11.
Asian J Endosc Surg ; 14(3): 548-552, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32996277

RESUMEN

Single-incision laparoscopic repair of a congenital Morgagni diaphragmatic hernia using a suture-assisting needle was performed in a 1-year-old boy. Three ports were inserted through a single umbilical incision to repair the 2.5 × 2.3-cm defect. The full-thickness muscle layer of the anterior abdominal wall and the posterior rim of the defect were penetrated with the suture-assisting needle holding a thread, which was then released. The needle tip was pulled back over the muscle layer, shifted laterally, and again passed through the muscle layer and the posterior rim. The thread was then captured by the needle and pulled out through the anterior abdominal wall. Five mattress sutures were placed in this way and tied subcutaneously. The postoperative course was uneventful, and the cosmetic outcome was favorable. A suture-assisting needle is useful for completing full-thickness anterior abdominal wall repair, which is important for preventing the recurrence of a congenital Morgagni diaphragmatic hernia.


Asunto(s)
Pared Abdominal , Hernias Diafragmáticas Congénitas , Laparoscopía , Pared Abdominal/cirugía , Hernias Diafragmáticas Congénitas/cirugía , Humanos , Lactante , Masculino , Agujas , Técnicas de Sutura , Suturas
12.
Biochim Biophys Acta Gen Subj ; 1864(2): 129361, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31077793

RESUMEN

BACKGROUND: Proteins change their conformation depending on function. Although a vast number of static pictures of proteins have been accumulated, information regarding their dynamics in function is limited. Diffracted X-ray tracking (DXT) is a good candidate to obtain the missing data. SCOPE OF REVIEW: A gold nanocrystal was attached to the target protein as a probe and the motion of the X-ray diffraction spots from the crystal corresponded to the motion of the target. Although it has advantages of high temporal (sub-millisecond) and spatial (approximately 0.1°) resolutions, it is not extensively utilized. This review focused on its effective application from a user's perspective. We also present an example with the KcsA channel and the status of recent developments to show the future possibilities of the method. MAJOR CONCLUSIONS: DXT is a powerful method to investigate intramolecular structural changes. For instance, in the KcsA channel, the method revealed a wave of conformational changes transmitted from the gate region to the end of the molecule. The method is continuously being developed, and users can choose an appropriate measurement system depending on the condition of their sample. GENERAL SIGNIFICANCE: Revealing the protein structural changes with respect to function is an important frontier. The most distinctive feature of the DXT method is that both high temporal and spatial resolutions are achievable, and it is possible to track the motions of multiple molecules at the same time. This feature is an advantage for screening molecules associated with the target proteins (e.g., ligands and medicines).


Asunto(s)
Movimiento (Física) , Proteínas/química , Difracción de Rayos X , Oro/química , Concentración de Iones de Hidrógeno , Iones , Ligandos , Nanopartículas del Metal/química , Nanotecnología , Canales de Potasio/química , Conformación Proteica , Relación Estructura-Actividad , Compuestos de Sulfhidrilo/química
13.
Surg Case Rep ; 5(1): 199, 2019 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-31845000

RESUMEN

BACKGROUND: The surgical strategy for congenital perineal lipoma varies depending on the size, location, and accompanying congenital anomalies, with the optimum approach remaining to be determined. We herein report a case of congenital perianal lipoma that was first detected by prenatal ultrasound and review the literature. CASE PRESENTATION: A female neonate was referred to us for the evaluation of a perianal mass. She had been considered to be male prenatally because fetal ultrasound showed a perineal mass similar to a scrotum and penis. A postnatal examination revealed an appropriate-for-age neonate with a soft round mass 1.5 cm in diameter just to the left of the anal verge. She passed urine and stool smoothly, and contrast enema confirmed no anorectal malformation. Magnetic resonance imaging showed that the lesion had a signal intensity consistent with fat located close to the anal sphincter, and no spinal anomaly (e.g., spina bifida) was identified. We excised the lesion (pathologically confirmed to be lipoma) simply at 2 months old, taking care to avoid damaging the anal sphincter by using a muscle stimulator. She has been doing well with good bowel movement and satisfactory cosmetic results for a follow-up period of one and a half years. Our literature search revealed 49 cases of perineal lipoma reported in English in the last 25 years, and 74% of them-including ours-had other congenital anomalies, the breakdown of which was anorectal malformation in 40% of cases, labioscrotal fold or accessory scrotum in 28%, and urogenital malformation, congenital pulmonary airway malformation, and disorder of sex differentiation. The prenatal detection of the lesion, as in our case, was quite rare. CONCLUSION: A thorough physical examination after birth, magnetic resonance imaging and contrast enema to identify the nature of the perineal lipoma and accompanying anomalies are crucial for planning the surgical strategy. The lesion may be deeply interspersed between the sphincter muscle, especially when it accompanies anorectal anomaly. A muscle stimulator is useful for preserving and repairing the sphincter muscles during resection in order to ensure satisfactory bowel movement.

14.
J Pediatr Surg ; 54(12): 2617-2620, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31669127

RESUMEN

BACKGROUND: Eppikajutsuto (TJ-28) is an herbal medicine recently reported to be effective in treating lymphatic malformations (LMs). We report our experience concerning the clinical efficacy of TJ-28 for LMs. METHODS: Medical records of 10 LM cases treated with TJ-28 between 2016 and 2018 were reviewed. TJ-28 was given at 0.3 g/kg/day and then increased to 0.5 if no improvement was noted after the first three months of treatment. Their clinical data were collected, and LM volume indices (depth×width×height) were measured with the first (LMVI-F) and latest (LMVI-L) imaging studies. The response rates were calculated as 1-LMVI-L / LMVI-F (%). RESULTS: The median age at the diagnosis and treatment period was 1.5 years and 17.5 months, respectively. LMs were located in the neck (six), mesenterium or retroperitoneum (three), and inguinal region (one). The median response rate was 83%, including 100% in three cases and the apparent improvement of obstructive airway symptoms in one case. One case underwent surgery for insufficient improvement, and another that showed no effect is being considered for surgery. Most of the satisfactory outcomes were demonstrated in the first six months of treatment. CONCLUSION: TJ-28 seems to be effective in treating LMs in children, especially early in treatment. LEVEL OF EVIDENCE: IV.


Asunto(s)
Anomalías Linfáticas/tratamiento farmacológico , Extractos Vegetales/uso terapéutico , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Preparaciones Farmacéuticas , Estudios Retrospectivos
15.
Case Rep Pediatr ; 2019: 2659089, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31871811

RESUMEN

Adenomyomatosis of the gallbladder (AMG) is characterized by mucosal hyperplasia leading to invagination through the thickened muscle layer, which is relatively common in adults, but is rare in childhood. We report a 12-year-old boy with adenomyomatosis of the gallbladder combined segmental and fundal type. This combined type is rare in adults and is first reported here in childhood. Although initial imaging with computed tomography (CT) suggested the presence of a circular solid mass-like lesion because of its rare morphology, repeated ultrasonography (US) was useful for leading to a correct diagnosis.

16.
Mol Pharmacol ; 73(6): 1643-51, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18326583

RESUMEN

The human ether-à-go-go related gene product (HERG) channel is essential for electrical activity of heart cells, and block of this channel by many drugs leads to lethal arrhythmias. Tyr(652) and Phe(656) of the sixth transmembrane helix are candidates for the drug binding site. In the tetrameric HERG channel, a drug with asymmetric structure should interact unevenly with multiple residues from different subunits. To elucidate the topology of the drug-binding site, we constructed tandem dimers of HERG channels and the aromatic Tyr(652) and Phe(656) residues were replaced by alanine singly or doubly. Eight types of HERG channels, including homotetrameric mutants, having different numbers and arrangements of aromatic residues at the blocking site, were studied. Effects of cisapride on channels expressed in Xenopus laevis oocytes were examined electrophysiologically. The inhibition constants (K(i)) were increased significantly as the diagonal Tyr(652) were deleted, whereas those for the diagonal Phe(656)-deleted mutant were not changed. These results suggest that Tyr(652) residues from adjacent subunits contributed to the binding. Two types of double mutants of tandem dimers showed significantly distinct affinities, suggesting that the coexistence of Tyr(652) and Phe(656) on a subunit in diagonal position is crucial to having a high affinity. Thermodynamic double-mutant cycle analyses revealed interactions between Tyr(652) and Phe(656) upon binding. The kinetics and voltage-dependence of blocking suggested transitions of the binding site from low to high affinity. These approaches using a set of mutant HERG channels gave a dynamic picture of the spatial arrangements of residues that contribute to the drug-channel interaction.


Asunto(s)
Canales de Potasio Éter-A-Go-Go/química , Canales de Potasio Éter-A-Go-Go/metabolismo , Animales , Sitios de Unión/fisiología , Línea Celular , Cisaprida/metabolismo , Dimerización , Canales de Potasio Éter-A-Go-Go/antagonistas & inhibidores , Canales de Potasio Éter-A-Go-Go/genética , Femenino , Humanos , Mutación/fisiología , Xenopus laevis
17.
Elife ; 72018 04 17.
Artículo en Inglés | MEDLINE | ID: mdl-29661272

RESUMEN

Gram-negative bacteria import essential nutrients such as iron and vitamin B12 through outer membrane receptors. This process utilizes proton motive force harvested by the Ton system made up of three inner membrane proteins, ExbB, ExbD and TonB. ExbB and ExbD form the proton channel that energizes uptake through TonB. Recently, crystal structures suggest that the ExbB pentamer is the scaffold. Here, we present structures of hexameric complexes of ExbB and ExbD revealed by X-ray crystallography and single particle cryo-EM. Image analysis shows that hexameric and pentameric complexes coexist, with the proportion of hexamer increasing with pH. Channel current measurement and 2D crystallography support the existence and transition of the two oligomeric states in membranes. The hexameric complex consists of six ExbB subunits and three ExbD transmembrane helices enclosed within the central channel. We propose models for activation/inactivation associated with hexamer and pentamer formation and utilization of proton motive force.


Asunto(s)
Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Multimerización de Proteína , Microscopía por Crioelectrón , Cristalografía por Rayos X , Procesamiento de Imagen Asistido por Computador , Fuerza Protón-Motriz
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 75(6 Pt 1): 061802, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17677289

RESUMEN

We investigate the density fluctuations in crystalline polymers under uniaxial stretch in the order of submicrons to microns with two-dimensional ultrasmall-angle x-ray scattering. Before uniaxial stretch, we found isotropic density fluctuations obeying the mass fractal with the fractal dimension 2.6. After uniaxial stretch, the isotropic scattering pattern was transformed into the butterfly pattern. The butterfly pattern is caused by the stress-induced density fluctuations and the heterogeneous deformation associating with the spatial heterogeneity of stress field due to the distribution of crystalline and amorphous regions.

19.
J Gen Physiol ; 126(5): 529-38, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16260841

RESUMEN

The streaming potential (V(stream)) is a signature feature of ion channels in which permeating ions and water molecules move in a single file. V(stream) provides a quantitative measure of the ion and water flux (the water-ion coupling ratio), the knowledge of which is a prerequisite for elucidating the mechanisms of ion permeation. We have developed a method to measure V(stream) with the whole-cell patch-clamp configuration. A HEK293 cell stably expressing the HERG potassium channel was voltage clamped and exposed to hyperosmotic solutions for short periods of time (<1 s) by an ultrafast solution switching system (the osmotic pulse [quick jump-and-away] method). The reversal potentials were monitored by a series of voltage ramps before, during, and after the osmotic pulse. The shifts of the reversal potentials immediately after the osmotic jump gave V(stream). In symmetrical K+ solutions (10 mM), the V(stream)s measured at different osmolalities showed a linear relationship with a slope of -0.7 mV/DeltaOsm, from which the water-ion coupling ratio (n, the ratio of the flux of water to the flux of cations; Levitt, D.G., S.R. Elias, and J.M. Hautman. 1978. Biochim. Biophys. Acta. 512:436-451) was calculated to be 1.4. In symmetrical 100 mM K+ solutions, the coupling ratio was decreased significantly (n = 0.9), indicating that the permeation process through states with increased ion occupancy became significant. We presented a diagrammatic representation linking the water-ion coupling ratio to the mode of ion permeation and suggested that the coupling ratio of one may represent the least hydrated ion flux in the single-file pore.


Asunto(s)
Canales de Potasio Éter-A-Go-Go/fisiología , Canales de Potasio/efectos de los fármacos , Canales de Potasio/fisiología , Potasio/farmacología , Agua/farmacología , Permeabilidad de la Membrana Celular/efectos de los fármacos , Permeabilidad de la Membrana Celular/fisiología , Células Cultivadas/fisiología , Conductividad Eléctrica , Humanos , Modelos Biológicos , Concentración Osmolar , Presión Osmótica/efectos de los fármacos , Técnicas de Placa-Clamp/métodos , Potasio/fisiología , Transfección , Agua/fisiología
20.
J Exp Anal Behav ; 86(2): 239-51, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17002230

RESUMEN

This study tested the notion that an equivalence relation may include a response when differential responses are paired with stimuli presented during training. Eight normal adults learned three kinds of computer mouse movements as differential response topographies (R1, R2, and R3). Next, in matching-to-sample training, one of the response topographies was used to select a comparison stimulus B (B1, B2, or B3) conditionally upon presentation of sample stimulus A (A1, A2, or A3), and to select stimulus D (D1, D2, or D3) conditionally upon presentation of stimulus C (C1, C2, or C3). After two sample-comparison-response relations (ABR and CDR) were established, 18 sample-comparison relations were tested (BA, DC, RA, RB, RC, RD, AC, CA, AD, DA, BC, CB, BD, DB, AA, BB, CC, and DD). In the RA, RB, RC, and RD tests, the differential responses (R1, R2, and R3) were used as sample stimuli. All subjects made class-consistent comparison selections in the tests. This study provides evidence that responses may become members of an equivalence class.


Asunto(s)
Aprendizaje por Asociación , Aprendizaje Discriminativo , Orientación , Reconocimiento Visual de Modelos , Desempeño Psicomotor , Adulto , Retroalimentación Psicológica , Femenino , Humanos , Masculino , Recuerdo Mental , Solución de Problemas
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