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1.
Clin Radiol ; 77(12): 935-942, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36302714

RESUMO

AIM: To identify the magnetic resonance imaging (MRI) features of metastases to the extraocular muscles (EOM metastases). MATERIAL AND METHODS: The MRI features of 19 patients with EOM metastases were compared with those of 24 patients with EOM diseases of non-thyroid origin. MRI was used to assess the number of tumours, morphology, signal intensity on T2-weighted images, enhancement patterns, and apparent diffusion coefficient (ADC) values. RESULTS: Single muscular involvement was observed in 10 patients, and multiple muscular involvement was observed in nine patients. The morphology was focally discrete in nine patients, and diffuse infiltrative in 10 patients; all the nine patients with focal discrete morphology presented with single muscular lesions. On T2-weighted images, the signal intensities were intermediate or low in 15 patients and a mixture of high and intermediate in four patients. In 14 patients for whom contrast-enhanced images were available, ring enhancement (n=5), heterogeneous diffuse enhancement (n=5), and homogeneous enhancement (n=4) were seen. The mean ADC value was 0.98 × 10-3 mm2/s. Compared to other EOM diseases of non-thyroid origin, single muscular presentation, focal discrete morphology, the presence of hyperintensity on T2-weighted images, and ring or heterogeneous enhancement were significantly more frequent in EOM metastases. CONCLUSION: The MRI features of EOM metastases showed two main patterns: a single discrete mass and multiple infiltrative masses. In addition to the presentation as a single discrete mass, the presence of hyperintensity on T2-weighted images and ring or heterogeneous enhancement can aid in the differentiation of EOM metastases from other EOM diseases.


Assuntos
Músculos Oculomotores , Doenças Orbitárias , Humanos , Músculos Oculomotores/diagnóstico por imagem , Músculos Oculomotores/patologia , Meios de Contraste , Imageamento por Ressonância Magnética/métodos , Imagem de Difusão por Ressonância Magnética/métodos , Estudos Retrospectivos
2.
Phys Chem Chem Phys ; 18(10): 7085-92, 2016 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-26884096

RESUMO

The exact structure of the rutile-TiO2(110)-(1 × 2) surface, which had been under debate over the past 30 years, was investigated using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD), which is a positron counterpart of reflection high-energy electron diffraction (RHEED). The rocking-curves for the 00-spot obtained from the experimental diffraction patterns were compared to the curves for various models calculated with a full-dynamical theory. It was found that the rocking-curves matched those for a surface consisting of a Ti2O3 configuration, originally suggested by Onishi and Iwasawa [H. Onishi and Y. Iwasawa, Surf. Sci., 1994, 313, L783], but with a further modification of atomic positions close to the ones proposed by Wang et al. [Q. Wang, A. R. Oganov, Q. Zhu and X. F. Zhou, Phys. Rev. Lett., 2014, 113, 266101]. This result demonstrates that TRHEPD can distinguish between the existence and absence of the oxygen atoms on the topmost surface, and between the Ti atoms residing in positions at the interstitial-vertical sites and those at interstitial-horizontal sites.

3.
Regul Toxicol Pharmacol ; 73(3): 953-9, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26382610

RESUMO

This study reports on variation in the yields of N-nitrosonornicotine (NNN) and (4-methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK) from the mainstream smoke of cigarette brands and describes factors affecting this variation. Yields of NNN and NNK from smoke and tobacco filler, which is blended and cut tobacco filled in a cigarette tube, together with cigarette design parameters, were measured for 11 commercial cigarette brands, which were available in Japan from 2009 to 2013. The ranges of the relative standard deviations (RSDs) for NNN from the smoke of each brand were 5.0%-29.9% under International Organization for Standardization (ISO) and 6.3%-26.3% under Health Canada Intense (HCI) smoking regime. When these RSDs were compared with those of tar, nicotine, and carbon monoxide yields in each brand, they were found to be much higher for all of the brands under the HCI, and higher for most of the brands under the ISO smoking regime. In addition, the RSDs of NNN and NNK in smoke were mostly higher than those of KY3R4F which was manufactured in a single batch. It was identified that variation in NNN yields from tobacco filler mainly contribute to variation in NNN yields from smoke.


Assuntos
Nitrosaminas/análise , Fumaça/análise , Fumar , Produtos do Tabaco , Japão , Controle de Qualidade , Fatores de Tempo , Produtos do Tabaco/normas
4.
Phys Chem Chem Phys ; 16(48): 26991-6, 2014 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-25380102

RESUMO

Effects on the mechanical strength of poly-L-lactic acid (PLLA) upon irradiation with 150 keV He(+) ion were studied. Changes in the irradiated surface were investigated using a surface texture and contour measuring instrument and an atomic force microscope. Observations made with the atomic force microscope revealed that the irradiated surface subsided significantly as the fluence increased. In order to investigate the dependence on fluence of the depth of the Bragg peak for the ion implantation, the cutting strength, Σ, was analysed [F. Saito, I. Nishiyama and T. Hyodo, Mater. Lett., 2012, 66, 144-146]; this value is an indicator of the strength of a material against cutting, and is obtained from the cutting resistance. The averaged ion projected range increased from about 1.1 µm for a fluence of 1 × 10(15) He(+)/cm(2) to about 4 µm for a fluence of 1 × 10(16) He(+)/cm(2). The density of the region following irradiation was estimated using a combination of cutting resistance measurements and positron annihilation γ ray Doppler broadening measurements made with an energy-variable positron beam. The density decreased from the value of 1.27 g cm(-3) to about 0.6 g cm(-3) after irradiation with a fluence of 3 × 10(15) He(+)/cm(2). By considering the decrease in the density and the subsidence of the surface, it is concluded that only 30% of the original weight remained in the irradiated region after exposure to the He(+) ions. Anisotropic change in the cutting resistance suggests that mechanical strength in the direction normal to the surface increased while that in the lateral direction decreased.

5.
Regul Toxicol Pharmacol ; 67(3): 486-98, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24113618

RESUMO

A nicotine part-filter method can be applied to estimate smokers' mouth level exposure (MLE) to smoke constituents. The objectives of this study were (1) to generate calibration curves for 47 smoke constituents, (2) to estimate MLE to selected smoke constituents using Japanese smokers of commercially available cigarettes covering a wide range of International Organization for Standardization tar yields (1-21mg/cigarette), and (3) to investigate relationships between MLE estimates and various machine-smoking yields. Five cigarette brands were machine-smoked under 7 different smoking regimes and smoke constituents and nicotine content in part-filters were measured. Calibration curves were then generated. Spent cigarette filters were collected from a target of 50 smokers for each of the 15 brands and a total of 780 filters were obtained. Nicotine content in part-filters was then measured and MLE to each smoke constituent was estimated. Strong correlations were identified between nicotine content in part-filters and 41 out of the 47 smoke constituent yields. Estimates of MLE to acetaldehyde, acrolein, 1,3-butadiene, benzene, benzo[a]pyrene, carbon monoxide, and tar showed significant negative correlations with corresponding constituent yields per mg nicotine under the Health Canada Intense smoking regime, whereas significant positive correlations were observed for N-nitrosonornicotine and (4-methylnitrosoamino)-1-(3-pyridyl)-1-butanone.


Assuntos
Exposição por Inalação/análise , Mucosa Bucal , Fumaça/análise , Alcatrões/análise , Produtos do Tabaco/análise , Adulto , Calibragem , Técnicas de Química Analítica , Filtração , Humanos , Pessoa de Meia-Idade , Modelos Biológicos , Mucosa Bucal/efeitos dos fármacos , Mucosa Bucal/metabolismo , Nicotina/análise , Valor Preditivo dos Testes , Fumaça/efeitos adversos , Fumar/efeitos adversos , Fumar/metabolismo , Alcatrões/efeitos adversos , Produtos do Tabaco/efeitos adversos
6.
Phys Rev Lett ; 106(15): 153401, 2011 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21568556

RESUMO

Photodetachment of the positronium negative ion, a bound state of one positron and two electrons, has been observed. Development of a method to produce the ions efficiently using a Na coated tungsten surface has enabled the first observation of the photodetachment. The obtained lower limit of the photodetachment cross section for the wavelength of 1064 nm is consistent with the theoretical calculations reported so far. The experimental field developed in the present work gives new opportunities to explore the quantum mechanical three-body problem and to develop energy-tunable positronium beams.

7.
Clin Nephrol ; 74(4): 282-7, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20875380

RESUMO

AIM: The aim of this study was to investigate the effects of ezetimibe on high-density lipoprotein (HDL) subspecies and serum amyloid A (SAA), an apolipoprotein mainly bound and transported by HDL particles, in patients with end-stage renal disease (ERSD), a condition typically characterized by high SAA- and low HDL-cholesterol (C ) levels. METHODS: 26 ERSD patients receiving hemodialysis (HD) were given ezetimibe (10 mg/d) for 6 - 8 weeks. HDL3 was separated from serum by a single precipitation method established by our group. HDL2 was estimated by subtracting HDL3 from total HDL. Serum amyloid A (SAA) was measured by the ELISA method. RESULTS: Ezetimibe significantly reduced remnant-like particle (RLP)-C, low-density lipoprotein (LDL)-C, and apolipoprotein (apo) B without affecting triglyceride, HDL-C and LCAT activities. HDL2-C levels were lower and HDL3-C was substantially lower in the HD patients than in the controls. Ezetimibe increased HDL2-apoAI but decreased HDL3-apoAI without affecting serum apoAI or AII. HDL-SAA was 5-fold higher in the HD patients than in the controls (56 ± 49 vs. 12 ± 9 µg/ml). Ezetimibe decreased HDL-SAA by 43 % (to 32 ± 36 µg/ml), and this inhibitory effect was exclusively attributable to a 72% reduction in HDL3-SAA in response to the ezetimibe treatment. The reduction of HDL3-SAA was significantly associated with increased HDL2-apo AI and reduced HDL3-apo AI. CONCLUSIONS: Ezetimibe treatment decreased "inflammatory" (SAA-containing) HDL3, and may thus have restored the anti-atherogenic function of HDL particles in ESRD patients.


Assuntos
Anticolesterolemiantes/farmacologia , Azetidinas/farmacologia , Lipoproteínas HDL3/análise , Diálise Renal , Proteína Amiloide A Sérica/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Apolipoproteína A-I/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Ezetimiba , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
8.
J Phys Condens Matter ; 28(47): 475002, 2016 11 30.
Artigo em Inglês | MEDLINE | ID: mdl-27662111

RESUMO

We have measured the time-of-flight of ortho-positronium emitted from Cs-, Na- and Li-coated single-crystal tungsten surfaces. The data obtained after the coating show a new positronium energy component with a specific energy loss in addition to the component whose emission energy is simply determined by the positron and the electron work functions. We suggest that this new component is attributed to the formation of positronium accompanied by inter-band transition and/or surface plasmon excitation at the surfaces.

9.
Cardiovasc Res ; 19(9): 578-83, 1985 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-4042123

RESUMO

Effect of two agents of adenosine deaminase inhibitor, 8-azaguanine and adenine, on myocardial reactive hyperaemia was tested in the anaesthetised open-chest dog. Reactive hyperaemic flow response of the circumflex coronary artery was observed following 5, 10, 15, 20 and 30 s coronary occlusions before, during and after infusion of 8-azaguanine and adenine, which are known as adenosine deaminase inhibitors. Intracoronary infusion of 8-azaguanine and adenine caused the minimum increase in the baseline coronary flow. Both the nucleic acids shifted the dose response curve of adenosine to the left. 8-azaguanine enhanced volume response of flow at all occlusion intervals tested. The infused dose of adenine also intensified volume response of flow after 5, 15, 20 and 30 s occlusions. Fifteen minutes after termination of the nucleic acid infusions, the reactive hyperaemia returned towards control levels. The results suggest that 8-azaguanine and adenine enhance myocardial reactive hyperaemia possibly by inhibiting adenosine deaminase to degradate myocardial interstitial adenosine to inosine.


Assuntos
Inibidores de Adenosina Desaminase , Adenosina/fisiologia , Arteriopatias Oclusivas/fisiopatologia , Coração/fisiopatologia , Hiperemia/fisiopatologia , Nucleosídeo Desaminases/antagonistas & inibidores , Adenina/farmacologia , Adenosina/farmacologia , Animais , Azaguanina/farmacologia , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Vasos Coronários , Cães
10.
Eur J Pharmacol ; 315(2): 119-25, 1996 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-8960874

RESUMO

The effects of trans-(+/-)-3,4-dichloro-N-methyl-N-(2-[1-pyrrolidinyl] cyclohexyl) benzeneacetamide methanesulfonate salt (U-50488H) on carbon monoxide (CO)-induced amnesia in mice were investigated using spontaneous alternation and step-down type passive avoidance tasks. The lower percentage alternation and shorter median step-down latency in the retention test of the CO-exposed group indicated that memory deficiency occurred in mice when behavioral testing commenced 5-7 days after CO exposure. Administration of U-50488H (0.21 and 0.64 mumol/kg s.c.) 25 min before spontaneous alternation performance or the first training session of the passive avoidance task improved the CO-induced impairment of alternation performance and passive avoidance tasks. To determine whether the effect of U-50488H was mediated via kappa-opioid receptors, we attempted to block its action using a selective kappa-opioid receptor antagonist (nor-binaltorphimine). Nor-binaltorphimine (5.44 nmol/mouse i.c.v.) blocked the effect of U-50488H on CO-induced delayed amnesia. Furthermore, a low dose of scopolamine (0.41 mumol/kg s.c.) also blocked the ameliorating effect of U-50488H. U-50488H (0.21-2.15 mumol/kg s.c.) did not facilitate the acquisition of memory in normal mice. These results suggest that U-50488H modulates the kappa-opioid receptor-mediated opioid neuronal system and activates the cholinergic neuronal system, and that it ameliorates the disruptive effect of CO on acquisition and/or consolidation of memory.


Assuntos
Amnésia/induzido quimicamente , Amnésia/tratamento farmacológico , Analgésicos/uso terapêutico , Aprendizagem da Esquiva/efeitos dos fármacos , Intoxicação por Monóxido de Carbono/tratamento farmacológico , Pirrolidinas/uso terapêutico , (trans)-Isômero de 3,4-dicloro-N-metil-N-(2-(1-pirrolidinil)-ciclo-hexil)-benzenoacetamida , Analgésicos/antagonistas & inibidores , Animais , Estimulação Elétrica , Masculino , Camundongos , Naltrexona/análogos & derivados , Naltrexona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Pirrolidinas/antagonistas & inibidores
11.
Neurosci Lett ; 236(1): 45-8, 1997 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-9404948

RESUMO

We investigated whether carbachol, a muscarinic receptor agonist, induces learning and memory impairments, and U-50,488H, a selective kappa opioid receptor agonist, ameliorates the impairments of learning and memory using a step-down type passive avoidance task in mice. Carbachol induced a dose-related dual response. Carbachol (3 nmol/mouse, i.c.v.) significantly shortened the step-down latency, while lower (1 nmol) and higher (10 nmol) doses of carbachol did not induce learning and memory impairments. U-50,488H (0.64 micromol/kg, s.c.) significantly improved carbachol-induced impairments of learning and memory. These findings suggest that kappa opioid receptor agonists ameliorate learning and memory impairments which may associate with dysfunction of presynaptic cholinergic neurons.


Assuntos
(trans)-Isômero de 3,4-dicloro-N-metil-N-(2-(1-pirrolidinil)-ciclo-hexil)-benzenoacetamida/farmacologia , Aprendizagem da Esquiva/efeitos dos fármacos , Carbacol/farmacologia , Transtornos da Memória/tratamento farmacológico , Agonistas Muscarínicos/farmacologia , Receptores Opioides kappa/agonistas , Animais , Autorreceptores/agonistas , Relação Dose-Resposta a Droga , Injeções Intraventriculares , Masculino , Transtornos da Memória/induzido quimicamente , Camundongos
12.
J Gastroenterol ; 34(1): 105-10, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10204619

RESUMO

The development of endoscopic biliary stenting (EBS), using the Wallstent, to treat patients with obstructive jaundice secondary to unresectable tumors of the pancreas or biliary ducts has led to improved quality of life in these patients. We followed six patients with intraductal ultrasonography (IDUS) after insertion of a Wallstent. In two patients, endoscopic ultrasonography (EUS) was also performed, and in three patients IDUS was repeated every few months. IDUS allowed ingrowth of the tumor or formation of debris in the stent to be observed clearly and easily. Therefore IDUS was considered to be a powerful tool to follow patients after stenting and to decide on the next treatment when reobstruction occurred.


Assuntos
Ductos Biliares Intra-Hepáticos/diagnóstico por imagem , Cateterismo/métodos , Colestase/diagnóstico por imagem , Endossonografia , Stents , Idoso , Idoso de 80 Anos ou mais , Neoplasias dos Ductos Biliares/complicações , Colangiocarcinoma/complicações , Colestase/etiologia , Colestase/terapia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/complicações , Recidiva , Neoplasias Gástricas/complicações
13.
J Gastroenterol ; 31(6): 851-4, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9027651

RESUMO

In recent years, many cases of alpha-fetoprotein-producing gastric cancer (AFPGC) characterized by increased serum levels of alpha-fetoprotein (AFP) and AFP positivity of the gastric cancer have been reported. Here we present a case of AFPGC coexistent with a different histological type of gastric cancer: The AFPGC was Borrmann type 1 advanced gastric cancer with multiple liver metastasis and appeared to produce both AFP and des-gamma-carboxy prothrombin (PIVKA-II). The second cancer was IIc type early gastric cancer and did not produce AFP. Despite receiving palliative chemotherapy, the patient died, due to hepatic failure, 45 days after admission.


Assuntos
Adenocarcinoma/secundário , Biomarcadores , Neoplasias Hepáticas/secundário , Segunda Neoplasia Primária/patologia , Neoplasias Gástricas/patologia , alfa-Fetoproteínas/análise , Adenocarcinoma/química , Biomarcadores Tumorais , Biópsia , Evolução Fatal , Gastroscopia , Humanos , Imuno-Histoquímica , Neoplasias Hepáticas/química , Masculino , Pessoa de Meia-Idade , Segunda Neoplasia Primária/química , Precursores de Proteínas/análise , Protrombina/análise , Neoplasias Gástricas/química
14.
J Gastroenterol ; 34(5): 577-81, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10535484

RESUMO

Palliative duodenal stenting was attempted in three patients with severe duodenal stenosis due to tumor invasion. Two methods were applied for duodenal stenting: the conventional method, which inserts the Ultraflex (stent for esophageal stenosis) along the guidewire under fluoroscopy, and a new method that uses a snare and an endoscope to guide the esophageal stent. The conventional method is often unsuccessful, because the delivery tube is too short, but the latter method appears to be a safe and effective duodenal stenting technique.


Assuntos
Obstrução Duodenal/terapia , Duodenoscópios , Stents , Idoso , Neoplasias Duodenais/complicações , Neoplasias Duodenais/secundário , Obstrução Duodenal/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Paliativos
15.
J Gastroenterol ; 36(8): 557-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11519835

RESUMO

PURPOSE: We carried out this study to evaluate the usefulness of contrast-enhanced intraductal ultrasonography (ceIDUS) in the differentiation of thickened bile duct wall at the hepatic bifurcation caused by malignant tumor from that caused by cholangitis. METHODS: Seven patients (two with primary sclerosing cholangitis [PSC], one with secondary sclerosing cholangitis [SSC], and four with bile duct carcinomas [BDC] at the hepatic bifurcation underwent endoscopic ceIDUS, in which we used Levovist. The recorded images of echo-brightness were analyzed histographically. RESULTS: The bile duct wall, in PSC and SSC, but not in BDC, was enhanced by Levovist. CONCLUSION: ceIDUS with histographic analysis may be useful for distinguishing thickened bile duct wall caused by malignant tumor from that caused by cholangitis.


Assuntos
Ductos Biliares/diagnóstico por imagem , Colangite/diagnóstico por imagem , Endossonografia/métodos , Idoso , Neoplasias dos Ductos Biliares/diagnóstico por imagem , Colangiocarcinoma/diagnóstico por imagem , Meios de Contraste , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissacarídeos
16.
Clin Nephrol ; 58(1): 68-72, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12141410

RESUMO

A 67-year-old female was admitted to our hospital with eruption and cervical lymphadenopathy which occurred one week after pneumococcal vaccination. Polyclonal hyperimmunoglobulinemia (IgG 6,620 mg/dl) and mild plasma cell proliferation (6.4%) in a bone marrow specimen were found, but a lymph node aspiration biopsy showed no specific findings. Normochromic and normocytic anemia with a positive direct Coombs test were also confirmed. Short-term intensive steroid therapy was given, but the systemic eruption and lymphadenopathy continued. About 4 months after vaccination, she suffered from edema in her face and legs and visual disturbance. When massive proteinuria (10.4 g/day) was found, she was admitted to our ward. A renal biopsy specimen showed a minor glomerular abnormality with mild interstitial plasmacytic infiltration. An abdominal CT scan showed hepatosplenomegaly and para-aortic lymphadenopathy. Uveitis was also found by ophthalmoscopy. These abnormalities completely disappeared after intensive steroid therapy including pulse therapy. On the basis of her clinical course and laboratory findings, it was suggested that minimal change nephrotic syndrome might be induced after vaccination, possibly due to hypersensitivity syndrome.


Assuntos
Hipergamaglobulinemia/etiologia , Nefrose Lipoide/etiologia , Vacinas Pneumocócicas/efeitos adversos , Idoso , Feminino , Humanos , Rim/patologia , Doenças Linfáticas/etiologia , Metilprednisolona/uso terapêutico , Nefrose Lipoide/diagnóstico , Nefrose Lipoide/tratamento farmacológico , Tomografia Computadorizada por Raios X , Resultado do Tratamento
17.
Jpn J Physiol ; 33(5): 837-54, 1983.
Artigo em Inglês | MEDLINE | ID: mdl-6321831

RESUMO

Properties of Ca-dependent outward current were studied in bullfrog atrial muscle using double sucrose-gap techniques. Decreasing [Ca]o inhibited the instantaneous outward current (Ik1) and inward background current (Ib), and the reverse was noted with increases in [Ca]o. When gk1 was blocked with 0.3 mM Ba, there were no such effects. In the presence of Ba and TTX (1.5 X 10(-6)M), 3 mM Co abolished the slow inward current (Isi) and depressed the delayed outward current (Iout). The depression was confined to the voltage range of activation of Isi. Similar results were obtained by replacement of [Ca]o with Co in concentration of equal surface charge effects. Contrarily, isoproterenol (10(-7) M) increased the Isi and Iout at the same voltage range. The activation of Iout became more rapid in the presence of isoproterenol but slowed with Co. In the presence of Ba, TTX, and Co, Ca-free EGTA (approximately 0.3 mM) Ringer further depressed the Iout, eliminating any remaining tension response. The depression, however, was more extensive, the stronger the depolarization. The activation of Iout was markedly retarded and amplitude of the fully activated Iout diminished, yet the deactivation became more rapid. Thus, the Ca-sensitive outward current was classified into 1) Ca-linked Ik1, 2) Isi-dependent Iout, and 3) Isi-independent but [Ca]o-related Iout.


Assuntos
Cálcio/fisiologia , Coração/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Bário/farmacologia , Cálcio/antagonistas & inibidores , Cálcio/farmacologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , Césio/farmacologia , Cobalto/farmacologia , Ácido Egtázico/farmacologia , Condutividade Elétrica , Técnicas In Vitro , Canais Iônicos/efeitos dos fármacos , Canais Iônicos/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Potássio/fisiologia , Rana catesbeiana , Ratos , Tetrodotoxina/farmacologia
18.
Jpn J Physiol ; 32(4): 573-87, 1982.
Artigo em Inglês | MEDLINE | ID: mdl-6983615

RESUMO

Effects of Ca-free or Na-deficient Ringer solutions on the membrane currents of the bullfrog atrial muscle were studied using the double sucrose-gap method. Instantaneous outward current (Ik1) decreased in Ca-free and increased in Na-deficient conditions. The amplitude of nominal "fully activated delayed outward current" diminished under both sets of conditions. The diminution, however, was greater in Na-deficient medium (10 mM Na) and its activation curve shifted about 13.5 mV toward a more negative potential. In Ca-free Ringer, no such shift was observed, and the activation of the delayed outward current became slower and sigmoidal while the deactivation was faster than in the control. Contrarily, in Na-deficient Ringer, the activation became faster and exponential and the deactivation was slower. The current tail was composed of two exponentially declining components, and the slower, K-accumulation-related component (Ia) was suppressed in Ca-free and the faster component (Ixs) diminished in Na-deficient media. These findings may indicate that in the atrial muscle the instantaneous outward current is modified by a Na-Ca exchange mechanisms and that the delayed outward current consists of two components, Ixs and Ia, which are susceptible to Na and Ca ions, respectively.


Assuntos
Cálcio/fisiologia , Coração/fisiologia , Sódio/fisiologia , Animais , Técnicas In Vitro , Potenciais da Membrana , Rana catesbeiana
19.
Acta Med Okayama ; 37(5): 423-9, 1983 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-6650224

RESUMO

Stress-induced changes in the resistance due to coronary arterial stenosis of a fixed diameter and in the myocardial blood flow distal to the stenosis were investigated in the open-chest dog. Myocardial blood flow in the inner and outer third of the left ventricular wall was continuously measured with heated cross-thermocouples. The circumflex coronary artery was constricted with a thick string so that myocardial reactive hyperemia was nearly eliminated. Without constriction, a 15-second occlusion of the artery produced no significant changes in the resistance of large coronary arteries. On the contrary, in the presence of coronary constriction, a brief coronary occlusion caused a sustained decrease in distal coronary pressure and subendocardial myocardial flow during reactive hyperemia, while coronary flow returned quickly to the pre-occlusion level with significant reactive hyperemia of subepicardial flow. This change resulted in a long-lasting increase in the stenosis resistance. These results suggest that stenosis resistance changes dynamically, resulting in additional myocardial ischemia especially in the subendocardial myocardial layers.


Assuntos
Circulação Coronária , Doença das Coronárias/fisiopatologia , Resistência Vascular , Animais , Pressão Sanguínea , Constrição , Vasos Coronários , Cães , Feminino , Hiperemia , Masculino , Fatores de Tempo
20.
Acta Med Okayama ; 36(3): 199-205, 1982 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-7113744

RESUMO

Changes in the stenotic resistance of a coronary artery following brief coronary occlusion were studied in the anesthetized open-chest dog. A critical coronary stenosis was constructed by tying a thick string around the circumflex coronary artery (LCx) near its origin. The LCx was occluded for 5, 10, 15, 20 and 30 seconds with and without coronary stenosis then the reactive hyperemia was observed. In the absence of the stenosis, resistance of the segment of the large coronary artery remained unchanged during the reactive hyperemia independent of the duration of occlusion. In the presence of the stenosis, however, stenotic resistance increased for a certain time after the release of occlusion. This increased resistance lasted longer with more severe stenosis and with longer duration of coronary occlusion. These results suggest that stenotic resistance can increase dynamically, and that the duration of increased resistance may reflect the severity of the stenosis.


Assuntos
Doença das Coronárias/fisiopatologia , Resistência Vascular , Anestesia , Animais , Pressão Sanguínea , Cães , Feminino , Masculino
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