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1.
Phys Rev Lett ; 132(5): 051002, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38364164

RESUMO

We present the measurement of the cosmic ray proton spectrum from 50 TeV to 1.3 PeV using 7.81×10^{6} extensive air shower events recorded by the ground-based GRAPES-3 experiment between 1 January 2014 and 26 October 2015 with a live time of 460 day. Our measurements provide an overlap with direct observations by satellite and balloon-based experiments. The electromagnetic and muon components in the shower were measured by a dense array of plastic scintillator detectors and a tracking muon telescope, respectively. The relative composition of the proton primary from the air shower data containing all primary particles was extracted using the multiplicity distribution of muons which is a sensitive observable for mass composition. The observed proton spectrum suggests a spectral hardening at ∼166 TeV and disfavors a single power law description of the spectrum up to the Knee energy (∼3 PeV).

2.
Tech Coloproctol ; 25(1): 69-74, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32815047

RESUMO

BACKGROUND: Transanal (Ta) pelvic exenteration is a promising, minimally invasive method for treating locally advanced colorectal cancer. However, since it is technically difficult to perform, Ta pelvic exenteration is rarely reported in locally advanced T4 rectal cancer cases. The aim of this study was to evaluate the feasibility of transabdominal laparoscopy-assisted Ta pelvic exenteration. METHODS: Six patients (4 males and 2 females) had laparoscopy-assisted Ta total or posterior pelvic exenteration for locally advanced or recurrent colorectal cancer cases at the Nagasaki University Hospital between September 2018 and August 2019. Clinical and pathological outcomes were measured and analyzed. RESULTS: The median operation time and intraoperative blood loss were 481 (range 456-709) minutes and 352.5 (range 257-1660) ml, respectively. R0 resection was achieved in all cases, and no patient required open surgery. Two patients had grade 3 complications (Clavien-Dindo) or higher. There was no mortality, and no reoperation was required. CONCLUSIONS: The results suggest that laparoscopic-assisted Ta pelvic exenteration is an acceptable procedure, may help overcome the current technical difficulties, and may improve outcomes in patients with locally advanced rectal cancer.


Assuntos
Laparoscopia , Exenteração Pélvica , Neoplasias Retais , Estudos de Viabilidade , Feminino , Humanos , Masculino , Recidiva Local de Neoplasia/cirurgia , Neoplasias Retais/cirurgia , Estudos Retrospectivos
4.
Neuropathol Appl Neurobiol ; 42(3): 242-54, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26538301

RESUMO

AIMS: A hexanucleotide expansion in C9orf72 is the major genetic cause of inherited behavioural variant Frontotemporal dementia (bvFTD) and motor neurone disease (MND), although the pathological mechanism(s) underlying disease remains uncertain. METHODS: Using antibodies to poly-GA, poly-GP, poly-GR, poly-AP and poly-PR proteins, we examined sections of cerebral cortex, hippocampus, thalamus, cerebellum and spinal cord, from 20 patients with bvFTD and/or MND bearing an expansion in C9orf72 for aggregated deposits of dipeptide repeat proteins (DPR). RESULTS: Antibodies to poly-GA, poly-GP and poly-GR detected numerous rounded cytoplasmic inclusions (NCI) within granule cells of hippocampal dentate gyrus and those of the cerebellum, as well as 'star-burst' shaped NCI in pyramidal neurones of CA3/4 region of hippocampus. NCI were uncommon in Purkinje cells, and only very rarely seen in anterior horn cells. Poly-PA antibody detected occasional NCI within CA3/4 neurones alone, whereas poly-PR antibody did not identify any NCI but immunostained the nucleus of anterior horn cells, CA3/4 neurones and Purkinje cells, in patients with or without expansion in C9orf72, as well as in normal controls. Poly-GA antibody generally detected more DPR than poly-GP, which in turn was greater than poly-GR. All patients with bvFTD + MND or MND showed plentiful p62/TDP-43 positive inclusions in remaining anterior horn cells. CONCLUSION: Degeneration and loss of anterior horn cells associated with expansions in C9orf72 occurs in the absence of DPR, and implies that changes involving loss of nuclear staining for and a cytoplasmic aggregation of TDP-43 are more likely to be the cause of this.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Degeneração Lobar Frontotemporal/patologia , Doença dos Neurônios Motores/patologia , Degeneração Neural/patologia , Proteínas/genética , Idoso , Proteína C9orf72 , Expansão das Repetições de DNA , Dipeptídeos , Feminino , Degeneração Lobar Frontotemporal/genética , Humanos , Imuno-Histoquímica , Corpos de Inclusão/metabolismo , Corpos de Inclusão/patologia , Masculino , Pessoa de Meia-Idade , Doença dos Neurônios Motores/genética , Degeneração Neural/genética , Neurônios/patologia
6.
Science ; 382(6673): 903-907, 2023 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-37995237

RESUMO

Cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. Their arrival is infrequent, so detection requires instruments with large collecting areas. In this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the Telescope Array experiment. We calculate the particle's energy as [Formula: see text] (~40 joules). Its arrival direction points back to a void in the large-scale structure of the Universe. Possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics.

7.
Colorectal Dis ; 14(10): e740-6, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22709354

RESUMO

AIM: A case-controlled study was performed to investigate the association of colonic angiectasia with other conditions and to identify risk factors for bleeding. METHOD: Information was collected from all patients who underwent colonoscopy at our hospital between January 2008 and December 2010. Data on 90 individuals with angiectasia [58 men; median age 69 (26-92) years] were compared with those of 180 individuals without angiectasia, matched for gender and age. RESULTS: Multivariate analysis showed that occult gastrointestinal bleeding [odds ratio (OR) 2.523; 95% confidence interval (CI) 1.238-5.142], liver cirrhosis (OR 13.195; 95% CI 3.502-49.711), chronic renal failure (OR 6.796; 95% CI 1.598-28.904) and valvular heart disease (OR 6.425; 95% CI 1.028-40.165) were identified as significant predictors of the presence of colonic angiectasia. Eight patients were diagnosed with bleeding from angiectasia. Cardiovascular disease (OR 22.047; 95% CI 1.063-457.345) and multiple angiectasias (P-value 0.0019) were identified as significant risk factors for active bleeding. Medication and a large size were not associated with an increased risk of bleeding. CONCLUSION: The presence of colonic angiectasia was associated with valvular heart disease, liver cirrhosis and chronic renal failure. Valvular heart disease and multiple lesions increased the risk of bleeding.


Assuntos
Angiodisplasia/etiologia , Doenças do Colo/etiologia , Hemorragia Gastrointestinal/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Angiodisplasia/diagnóstico , Estudos de Casos e Controles , Doenças do Colo/diagnóstico , Colonoscopia , Feminino , Hemorragia Gastrointestinal/diagnóstico , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Retrospectivos , Fatores de Risco
8.
Clin Exp Rheumatol ; 28(1): 6-12, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20346231

RESUMO

OBJECTIVES: To evaluate the safety and potential efficacy of tacrolimus for the treatment of patients with lupus nephritis and persistent proteinuria. METHODS: A total of 23 Japanese patients with lupus nephritis (21 females/2 males) were enrolled in this study. Patients were administered tacrolimus at a dose of 2-3 mg once daily after the evening meal for 6 months. The dose of tacrolimus was unchanged throughout the study period. Concomitant prednisolone therapy was unchanged or gradually tapered, while other immunosuppressants were stopped at the start of tacrolimus treatment. RESULTS: Tacrolimus was well tolerated, and none of the patients developed adverse drug reactions that required discontinuation of the study. Daily urinary protein loss, the U-prot/U-creat ratio, and serum albumin were significantly improved after 4 months, 3 months, and 1 month of treatment with tacrolimus (p<0.05), respectively, and the improvement persisted until 6 months. The serum complement hemolytic activity (CH50), complement C3 level, and CRP level were also significantly improved after treatment with tacrolimus (p<0.05). Improvement of the U-prot/U-creat ratio was most prominent for patients who were in WHO class IV. CONCLUSIONS: Tacrolimus is safe and effective as maintenance therapy for patients with lupus nephritis, at least for 6 months. A larger randomised, controlled trial over a longer period is needed to confirm these results.


Assuntos
Imunossupressores/administração & dosagem , Nefrite Lúpica/tratamento farmacológico , Proteinúria/tratamento farmacológico , Tacrolimo/administração & dosagem , Adolescente , Adulto , Proteína C-Reativa/metabolismo , Complemento C3/metabolismo , Ensaio de Atividade Hemolítica de Complemento , Quimioterapia Combinada , Feminino , Glucocorticoides/administração & dosagem , Humanos , Imunossupressores/efeitos adversos , Masculino , Pessoa de Meia-Idade , Prednisolona/administração & dosagem , Tacrolimo/efeitos adversos , Resultado do Tratamento , Adulto Jovem
9.
Phytopathology ; 99(2): 209-16, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19159313

RESUMO

Bacterial shoot blight (BSB) disease, caused by Pseudomonas syringae pv. theae, is a major bacterial disease of tea plants in Japan. BSB mainly occurs in the low-temperature season, and lesion formation by P. syringae pv. theae is enhanced by both low temperature and the presence of ice nucleation-active Xanthomonas campestris (INAX), which catalyzes ice formation at -2 to -4 degrees C and is frequently co-isolated with P. syringae pv. theae from tea plants. Low temperature is thus the most important environmental factor influencing the incidence of BSB; however, the effects of low temperature on infection of the host by P. syringae pv. theae and of environmental controls in fields on the occurrence of the disease are poorly understood. In this study, we show that ice formation on tea leaves by INAX enhanced P. syringae pv. theae invasion into leaf tissue. The natural incidence of BSB in the field was closely related to early autumn frost. Frost protection in late autumn, which prevented ice formation on tea plants, significantly decreased the incidence of BSB, and frost protection combined with bactericide application held the incidence under the economic threshold level. Our data indicate that environmental control in the field based on microbial interactions in the host offers a new strategy for plant disease control.


Assuntos
Agricultura , Camellia sinensis/microbiologia , Meio Ambiente , Doenças das Plantas/microbiologia , Pseudomonas syringae/classificação , Antibacterianos/uso terapêutico , Controle Biológico de Vetores , Folhas de Planta/microbiologia , Pseudomonas syringae/efeitos dos fármacos , Estações do Ano , Temperatura , Fatores de Tempo
10.
J Neurol Neurosurg Psychiatry ; 79(10): 1153-8, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18403441

RESUMO

OBJECT: The pathophysiology of syringomyelia in Chiari type 1 malformations has not been clarified. Oedema-like spinal-cord swelling was recently reported in several pathological conditions, including Chiari type 1 malformations as a pre-syrinx state. However, the role of the pre-syrinx state in the development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformations. METHODS: Pre- and postoperative MRI findings in 14 patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualisation of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus. RESULTS: Twelve patients had large and expansive syrinx, whereas 2 patients showed small syrinx confined to the centre of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial oedema. CONCLUSIONS: From this study, the interstitial oedema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformations. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformations.


Assuntos
Malformação de Arnold-Chiari/complicações , Edema/etiologia , Doenças da Medula Espinal/etiologia , Siringomielia/etiologia , Adolescente , Adulto , Idoso , Malformação de Arnold-Chiari/diagnóstico , Criança , Diagnóstico Diferencial , Edema/diagnóstico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Doenças da Medula Espinal/patologia , Siringomielia/diagnóstico
11.
J Dent Res ; 97(6): 701-708, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29513618

RESUMO

Head and neck cancer is the sixth most common cancer worldwide. It remains one of the leading causes of death, and its early detection is crucial. Liquid biopsy has emerged as a promising tool for detecting and monitoring the disease status of patients with early and advanced cancers. Circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and exosomal miRNAs have received enormous attention because of their apparent clinical implications. Analyses of these circulating biomarkers have paved the way for novel therapeutic approaches and precision medicine. A growing number of reports have implicated the use of circulating biomarkers for detection, treatment planning, response monitoring, and prognosis assessment. Although these new biomarkers can provide a wide range of possible clinical applications, no validated circulating biomarkers have yet been integrated into clinical practice for head and neck cancer. In this review, we summarize the current knowledge of circulating biomarkers in this field, focusing on their feasibility, limitations, and key areas of clinical applications. We also highlight recent advances in salivary diagnostics and their potential application in head and neck cancer.


Assuntos
Neoplasias de Cabeça e Pescoço/diagnóstico , Biópsia Líquida , Biomarcadores Tumorais/análise , DNA de Neoplasias/análise , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Biópsia Líquida/métodos , Saliva/química
12.
Neurogastroenterol Motil ; 29(12)2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28631871

RESUMO

BACKGROUNDS: Chronic intestinal pseudo-obstruction (CIPO) is an intractable rare digestive disease manifesting persistent small bowel distension without any mechanical cause. Intestinal decompression is a key treatment, but conventional method including a trans-nasal small intestinal tube is invasive and painful. Therefore, a less invasive and tolerable new decompression method is urgently desired. We conducted a pilot study and assessed the efficacy and safety of percutaneous endoscopic gastro-jejunostomy (PEG-J) decompression therapy in CIPO patients. METHODS: Seven definitive CIPO patients (2 males and 5 females) were enrolled. All patients received PEG-J decompression therapy. The number of days with any abdominal symptoms in a month (NODASIM), body mass index (BMI), serum albumin level (Alb), and small intestinal volume before and after PEG-J were compared in all patients. RESULTS: Percutaneous endoscopic gastro-jejunostomy was well tolerated and oral intake improved in all patients. NODASIM has significantly decreased (24.3 vs 9.3 days/months) and BMI/Alb have significantly increased (14.9 vs 17.2 kg/m2 and 2.6 vs 3.8 g/dL, respectively), whereas total volume of the small intestine has not significantly reduced (4.05 vs 2.59 L, P=.18). Reflux esophagitis and chemical dermatitis were observed in one case but was successfully treated conservatively. CONCLUSIONS & INFERENCES: Percutaneous endoscopic gastro-jejunostomy decompression therapy can contribute greatly to improvement of abdominal symptoms and nutritional status in CIPO patients. Although sufficient attention should be paid to acid reflux symptoms, PEG-J has the potential to be a non-invasive novel decompression therapy for CIPO available at home. However, accumulation of more CIPO patients and long-term observation are needed (UMIN000017574).


Assuntos
Endoscopia Gastrointestinal/métodos , Gastrostomia/métodos , Pseudo-Obstrução Intestinal/cirurgia , Jejunostomia/métodos , Adulto , Idoso , Doença Crônica , Descompressão Cirúrgica/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Adulto Jovem
13.
J Thromb Haemost ; 4(6): 1271-8, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16706971

RESUMO

OBJECTIVES: Although the concept of aspirin resistance is extensively reported in medical literature, its precise mechanisms and clinical outcomes are largely unknown. In this study, we examined individual thromboxane biosynthesis and platelet aggregation in aspirin-treated patients, and whether the results of a platelet aggregation test influenced clinical outcomes. RESULTS: Subjects taking 81 mg of aspirin (n = 50) and controls (n = 38) were evaluated for platelet aggregation and platelet cyclooxygenase-1 (COX-1) activity by measuring collagen-induced thromboxane B2 production. For aggregometry, both light transmission (LT) and laser-light scattering methods were employed to quantitatively evaluate aggregate sizes and numbers. Aspirin treatment resulted in the inhibition of collagen-induced platelet aggregation, particularly the transition from small to large platelet aggregates. Although platelet COX-1 activity seemed to be uniformly inhibited in all patients, platelet aggregation studies showed great inter-individual differences; variation in platelet COX-1 activity only accounted for 6-20% of the individual aggregations. Factor analysis revealed the existence of a common factor (other than platelet COX-1) that explained 48.4% of the variations in platelet aggregation induced by collagen, adenosine diphosphate (ADP), and collagen-related peptide. We then prospectively enrolled 136 aspirin-treated patients in our study, and we found that being in the upper quartile level of LT, or with large aggregate formation induced by collagen, was an independent risk factor for developing cardiovascular events within 12 months [hazard ratio (HR) = 7.98, P = 0.008 for LT; HR = 7.76, P = 0.007 for large aggregates]. On the other hand, the existence of diabetes mellitus was an independent risk factor for overall outcomes (HR 1.30-11.9, P = 0.015-0.033). CONCLUSIONS: Aspirin resistance expressed as unsuppressed platelet COX-1 activity is a rare condition in an out-patient population. Other factor(s) affecting collagen-induced platelet aggregation may influence early outcomes in aspirin-treated patients.


Assuntos
Aspirina/farmacologia , Plaquetas/efeitos dos fármacos , Doenças Cardiovasculares/sangue , Inibidores de Ciclo-Oxigenase/farmacologia , Resistência a Medicamentos , Inibidores da Agregação Plaquetária/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Idoso , Aspirina/efeitos adversos , Plaquetas/enzimologia , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/urina , Colágeno/farmacologia , Ciclo-Oxigenase 1/metabolismo , Inibidores de Ciclo-Oxigenase/efeitos adversos , Feminino , Humanos , Masculino , Inibidores da Agregação Plaquetária/efeitos adversos , Testes de Função Plaquetária/métodos , Estudos Prospectivos , Fatores de Risco , Transdução de Sinais , Tromboxano B2/análogos & derivados , Tromboxano B2/metabolismo , Tromboxano B2/urina , Resultado do Tratamento
14.
Structure ; 4(1): 33-45, 1996 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-8805511

RESUMO

BACKGROUND: Mouse lung carbonyl reductase (MLCR) is a member of the short-chain dehydrogenase/reductase (SDR) family. Although it uses both NADPH and NADH as coenzymes, the structural basis of its strong preference for NADPH is unknown. RESULTS: The crystal structure of the ternary complex of MLCR (with NADPH and 2-propanol) has been determined at 1.8 A resolution. This is the first three-dimensional structure of a carbonyl reductase, and MLCR is the first member of the SDR family to be solved in complex with NADPH (rather than NADH). Comparison of the MLCR ternary complex with three structures reported previously for enzymes of the SDR family (all crystallized as complexes with NADH) reveals a pair of basic residues (Lys17 and Arg39) making strong electrostatic interactions with the 2'-phosphate group of NADPH. This pair of residues is well conserved among the NADPH-preferring enzymes of the SDR family, but not among the NADH-preferring enzymes. In the latter, an aspartate side chain occupies the position of the two basic side chains. The aspartate residue, which would come into unacceptably close contact with the 2'-phosphate group of the adenosine moiety of NADPH, is replaced by a threonine or alanine in the primary sequences of NADPH-preferring enzymes of the SDR family. CONCLUSIONS: The cofactor preferences exhibited by the enzymes of the SDR family are mainly determined by the electrostatic environment surrounding the 2'-hydroxyl (or phosphate) group of the adenosine ribose moiety of NADH (or NADPH). Thus, positively charged and negatively charged environments correlate with preference for NADPH and NADH respectively.


Assuntos
Oxirredutases do Álcool/química , 1-Propanol/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Coenzimas/metabolismo , Pulmão/metabolismo , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , NAD/metabolismo , NADP/química , NADP/metabolismo , Oxirredutases/química , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Especificidade por Substrato
15.
J Int Med Res ; 34(1): 65-72, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16604825

RESUMO

In this study, the effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2A receptor antagonist, on platelet aggregation at the site of injured carotid artery endothelium was examined. The rat common carotid artery was clamped for 30 min to induce endothelial injury. Sarpogrelate hydrochloride was administered before and after the injury, and the effects were compared with those in rats receiving sham operation only and those receiving clipping injury but no sarpogrelate hydrochloride. The animals were killed 24 h after the procedure. The common carotid artery was examined by scanning electron microscopy and stained immunochemically for factor VIII. Sarpogrelate hydrochloride treatment was associated with reduced aggregation of platelets on electron microscopy and lower expression of factor VIII at the injured intima. Sarpogrelate hydrochloride has an inhibitory effect on platelet aggregation at the intima in the acute stage after injury, suggesting that this drug may be used to prevent early ischaemic complications after surgical or endovascular arterial intervention.


Assuntos
Endotélio/lesões , Inibidores da Agregação Plaquetária/farmacologia , Receptores de Serotonina/metabolismo , Antagonistas da Serotonina/farmacologia , Succinatos/farmacologia , Animais , Artéria Carótida Primitiva/ultraestrutura , Esquema de Medicação , Endotélio/ultraestrutura , Fator VIII/metabolismo , Imuno-Histoquímica , Injeções Intraperitoneais , Masculino , Inibidores da Agregação Plaquetária/administração & dosagem , Ratos , Ratos Sprague-Dawley , Serotonina/metabolismo , Antagonistas da Serotonina/administração & dosagem , Succinatos/administração & dosagem , Túnica Íntima/ultraestrutura
16.
Rev Sci Instrum ; 87(5): 053309, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27250416

RESUMO

For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.

17.
Biochim Biophys Acta ; 1233(2): 163-74, 1995 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-7532435

RESUMO

Ion channels in the apical membrane of rat inner medullary collecting duct (IMCD) were investigated by the patch clamp technique. Owing to the histological heterogeneity of IMCD, cells were cultured from the lower half of the inner medulla of Wistar rat kidney. Channel activity was rarely seen in cell attached patch, but membrane excision activated multiple units of 28.2 +/- 0.7 pS cation selective channel. A Na or K selective channel was not found. The 28 pS channel showed membrane voltage dependency, no rectification, almost equal permeability to monovalent cations (Na/K/Li/Cs/Rb/NH4 = 1:1.00:0.82:0.97:1.10:1.71) and no significant permeation to anions or divalent cations. Calcium of the cytoplasmic side from 10(-7) M to 10(-4) M affected the mean number of open channels (nPo) dose-dependently in excised patch (IC50 = 5 x 10(-6) M). 1 mM of ATP, ADP, AMP and gadolinium reversibly suppressed nPo to near zero whereas amiloride, cAMP or cGMP had no effect. Multiple conductance substates were frequently observed. These results suggested that this channel belongs to the nonselective cation channels which has been identified in other epithelia and is not responsible for amiloride sensitive Na transport through IMCD cells.


Assuntos
Canais Iônicos/metabolismo , Medula Renal/metabolismo , Amilorida/farmacologia , Animais , Cátions Monovalentes , Células Cultivadas , Técnicas In Vitro , Ativação do Canal Iônico/efeitos dos fármacos , Masculino , Potenciais da Membrana/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Ratos Wistar
18.
Biochim Biophys Acta ; 1431(2): 306-14, 1999 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-10350607

RESUMO

The active site of sepiapterin reductase (SPR), which is a member of the NADP(H)-preferring short-chain dehydrogenase/reductase (SDR) family and acts as the terminal enzyme in the biosynthetic pathway of tetrahydrobiopterin cofactor (BH4), was investigated by truncation and site-directed mutagenesis. The truncation mutants showed that N-terminal and C-terminal residues contribute to bind coenzyme and substrate, respectively. The mutant rSPRA29V showed decreased activity; however, the A-X-L-L-S sequence, which has been reported as a putative pterin binding site, was estimated to preferably work as a component in the region for binding coenzyme rather than substrate. Site-directed mutants of rSPRS158D, rSPRY171V, and rSPRK175I showed low, but significant, activity having similar Km values and kcat/Km values less than 25%, for both sepiapterin and NADPH. Both amino acids Tyr-171 and Ser-158 are located within a similar distance to the carbonyl group of the substrate in the crystal structure of mouse SPR, and the double point mutant rSPRY171V+S158D was indicated to be inactive. These results showed that Ser-158, Tyr-171, and Lys-175 contributed to the catalytic activity of SPR, and both Tyr-171 and Ser-158 are simultaneously necessary on proton transfer to the carbonyl functional groups of substrate.


Assuntos
Oxirredutases do Álcool/química , Oxirredutases do Álcool/genética , Animais , Sítios de Ligação , Biopterinas/análogos & derivados , Biopterinas/biossíntese , Clonagem Molecular , DNA Complementar/metabolismo , Escherichia coli/metabolismo , Humanos , Mutagênese Sítio-Dirigida , Mutação , Ratos , Serina/química , Tirosina/química
19.
Biochim Biophys Acta ; 1266(1): 50-6, 1995 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-7718621

RESUMO

We investigated the effect of cyclic AMP (cAMP) on the pericellular fibrinolytic system in NY cells. Dibutyryl cAMP (dbcAMP) or forskolin increased the level of urokinase-type plasminogen activator (u-PA) mRNA and enhanced the secretion of u-PA antigen into the conditioned medium. These agents also increased u-PA antigen on the cell surface. PA inhibitor-1 (PAI-1) antigen was inhibited by dbcAMP or forskolin. Butyrate had no effect on the production and secretion of u-PA and PAI-1. A binding assay of 125I-DFP-u-PA to NY cells revealed a single class of binding sites with a Kd of 3.85 nM and Bmax of 0.89.10(5) binding sites/cell. The Bmax was increased by dbcAMP (1 mM or 10 mM), forskolin (2 microM or 20 microM) of 1.0-, 1.4-, 1.2- and 1.8-fold, respectively. However, the Kd value was not changed. Furthermore, the level of mRNA for the u-PA receptor (u-PAR) was increased by these agents 1.2-, 1.7-, 1.8- and 2.5-fold, respectively. However, butyrate did not alter either the Bmax or the u-PAR mRNA level. These results indicated that the pericellular fibrinolytic activity induced by u-PA/u-PAR is modulated by cAMP in osteoblast-like cells.


Assuntos
AMP Cíclico/farmacologia , Inibidor 1 de Ativador de Plasminogênio/biossíntese , Receptores de Superfície Celular/efeitos dos fármacos , Ativador de Plasminogênio Tipo Uroquinase/biossíntese , Bucladesina/farmacologia , Butiratos/farmacologia , Ácido Butírico , Linhagem Celular/efeitos dos fármacos , Colforsina/farmacologia , Fibrinólise/efeitos dos fármacos , Humanos , Osteoblastos , Inibidor 1 de Ativador de Plasminogênio/genética , RNA Mensageiro/análise , Receptores de Superfície Celular/genética , Receptores de Ativador de Plasminogênio Tipo Uroquinase
20.
J Mol Biol ; 255(2): 310-20, 1996 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-8551522

RESUMO

The three-dimensional structure of ribonuclease Rh (RNase Rh), a new class of microbial ribonuclease from Rhizopus niveus, has been determined at 2.0 A resolution. The overall structure of RNase Rh is completely different from those of other previously studied RNases, such as RNase A from bovine pancreas and RNase T1 from Aspergillus oryzae. In the structure of RNase Rh, two histidine residues (His46 and His109) and one glutamic acid residue (Glu105), which were predicted to be critical to the activity from the chemical modification and mutagenesis experiments, are found to be located close together, constructing the active site. The indole ring of Trp49 plays an important role in preserving the active site structure by its stacking interactions with the imidazole ring of His 109, and by hydrogen bonding with the carboxyl group of Glu105. There exists a hydrophobic pocket around the active site, which contains the aromatic side-chain of Trp49 and Tyr57. The results of mutagenesis studies suggest that this pocket is the base binding site of the substrate.


Assuntos
Endorribonucleases/química , Conformação Proteica , Rhizopus/enzimologia , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Ligação de Hidrogênio , Dados de Sequência Molecular , Ribonucleases/química , Alinhamento de Sequência
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