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1.
Phys Rev Lett ; 130(17): 173001, 2023 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-37172243

RESUMO

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high precision x-ray spectroscopy of the 5g-4f and 5f- 4d transitions (BSQED contribution of 2.4 and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the 5g_{9/2}- 4f_{7/2} transition energy to be 6297.08±0.04(stat)±0.13(syst) eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

2.
Phys Rev Lett ; 127(5): 053001, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34397250

RESUMO

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kß x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

3.
Opt Express ; 26(2): 1452-1460, 2018 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-29402019

RESUMO

Nonlinear optical processes are strongly dominated by phase relationships among electromagnetic fields involved. In this paper, we theoretically and experimentally show that in a Raman-resonant four-wave-mixing process, the first anti-Stokes and Stokes generations can be tailored in a variety of ways by manipulating the phase relationships among the relevant electromagnetic fields.

4.
Phys Rev Lett ; 116(16): 161101, 2016 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-27152783

RESUMO

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12} GeV^{-1} for ALP masses 0.5≲m_{a}≲5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

5.
J Fish Biol ; 86(4): 1335-47, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25846857

RESUMO

The growth and mortality rates of Myctophum affine larvae were analysed based on samples collected during the austral summer and winter of 2002 from south-eastern Brazilian waters. The larvae ranged in size from 2·75 to 14·00 mm standard length (L(S)). Daily increment counts from 82 sagittal otoliths showed that the age of M. affine ranged from 2 to 28 days. Three models were applied to estimate the growth rate: linear regression, exponential model and Laird-Gompertz model. The exponential model best fitted the data, and L(0) values from exponential and Laird-Gompertz models were close to the smallest larva reported in the literature (c. 2·5 mm L(S)). The average growth rate (0·33 mm day(-1)) was intermediate among lanternfishes. The mortality rate (12%) during the larval period was below average compared with other marine fish species but similar to some epipelagic fishes that occur in the area.


Assuntos
Peixes/crescimento & desenvolvimento , Modelos Biológicos , Animais , Tamanho Corporal , Brasil , Larva/crescimento & desenvolvimento , Modelos Lineares , Estações do Ano
6.
J Fish Biol ; 86(2): 822-826, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25545049

RESUMO

Efficiency of the identification of eggs of Engraulis anchoita can be greatly improved by a method developed from egg measurements, using photography and the ImageJ programme, analysed by discriminant analysis using R software.

7.
J Fish Biol ; 77(10): 2248-67, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21155781

RESUMO

This paper establishes the spawning habitat of the Brazilian sardine Sardinella brasiliensis and investigates the spatial variability of egg density and its relation with oceanographic conditions in the shelf of the south-east Brazil Bight (SBB). The spawning habitats of S. brasiliensis have been defined in terms of spatial models of egg density, temperature-salinity plots, quotient (Q) analysis and remote sensing data. Quotient curves (Q(C)) were constructed using the geographic distribution of egg density, temperature and salinity from samples collected during nine survey cruises between 1976 and 1993. The interannual sea surface temperature (SST) variability was determined using principal component analysis on the SST anomalies (SSTA) estimated from remote sensing data over the period between 1985 and 2007. The spatial pattern of egg occurrences in the SBB indicated that the largest concentration occurred between Paranaguá and São Sebastião. Spawning habitat expanded and contracted during the years, fluctuating around Paranaguá. In January 1978 and January 1993, eggs were found nearly everywhere along the inner shelf of the SBB, while in January 1988 and 1991 spawning had contracted to their southernmost position. The SSTA maps for the spawning periods showed that in the case of habitat expansion (1993 only) anomalies over the SBB were zero or slightly negative, whereas for the contraction period anomalies were all positive. Sardinella brasiliensis is capable of exploring suitable spawning sites provided by the entrainment of the colder and less-saline South Atlantic Central Water onto the shelf by means of both coastal wind-driven (to the north-east of the SBB) and meander-induced (to the south-west of the SBB) upwelling.


Assuntos
Ecossistema , Peixes , Óvulo , Comportamento Sexual Animal , Animais , Oceano Atlântico , Brasil , Geografia , Modelos Estatísticos , Densidade Demográfica , Salinidade , Temperatura , Zooplâncton
8.
Opt Express ; 16(23): 18667-74, 2008 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-19581952

RESUMO

We present a technique that enhances the intensity of a nanosecond laser pulse by confining it in an enhancement cavity. The point of the technique is that a weak continuous-wave laser radiation, locked to the enhancement cavity, is injected into a nanosecond injection-locked pulsed laser as a seed. This leads to a stable confinement of the nanosecond pulse in the enhancement cavity. It is demonstrated that the pulsed intensity is enhanced by a factor of 120 for a 40-ns pulse, consistent with the theoretical prediction.


Assuntos
Lasers , Nanotecnologia/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Transdutores , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
J Am Coll Cardiol ; 21(3): 604-11, 1993 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-8436741

RESUMO

OBJECTIVES: The purpose of this study was to examine the histologic-angiographic correlates of chronic total coronary occlusion and to explain why a tapering type of occlusion and short occluded segments are favorable for percutaneous transluminal coronary angioplasty. BACKGROUND: Coronary angioplasty is less successful for vessels with chronic total occlusion than for highly stenotic but patent vessels. Several clinical and angiographic factors determining the rate of initial success have been investigated, but the underlying histologic features are not clear. METHODS: Ten autopsy hearts that showed chronic total coronary occlusion on cineangiography performed < or = 3 months before death were selected. In all, the estimated duration of occlusion was > 1 year. At autopsy, postmortem angiography was performed and hearts were fixed with 10% buffered formalin. Occluded segments were sectioned transversely and serially into slices 10 microns thick. Every five slices were stained in hematoxylin-eosin and elastic van-Gieson. RESULTS: Ten hearts with chronic total coronary occlusion were angiographically classified into five with a tapering and five with an abrupt type of occlusion and seven with a short (< or = 15 mm) and three with a long (> 15 mm) occluded segment. Histologically, the occluded segment was composed of loose or dense fibrous tissue, atheroma, small vascular channels and calcified tissue. Reconstruction of the serial preparations showed that small lumen recanalized areas (diameter 160 to 230 microns) with surrounding loose fibrous tissue penetrated the occluded segment in four hearts with occlusion of the tapering type and a short occluded segment. In these four cases, the lack of anterograde flow on cineangiography could be explained by the presence of rich collateral flow. In three cases of the abrupt type of occlusion with a short occluded segment, a mass of loose fibrous tissue penetrated the occluded segment. In hearts with a long occluded segment (one with a tapering type of occlusion and two with an abrupt type), there was no recanalization and loose fibrous tissue was dispersed in the occluded segment. CONCLUSIONS: Chronic total coronary occlusion of the tapering type or with a short occluded segment, or both, is possibly favorable for angioplasty, because small lumen recanalized areas or loose fibrous tissue penetrates the occluded segment and may form a route for successful angioplasty.


Assuntos
Angioplastia Coronária com Balão , Arteriopatias Oclusivas/terapia , Doença das Coronárias/terapia , Vasos Coronários/patologia , Miocárdio/patologia , Idoso , Idoso de 80 Anos ou mais , Arteriopatias Oclusivas/diagnóstico por imagem , Arteriopatias Oclusivas/patologia , Cineangiografia , Angiografia Coronária , Doença das Coronárias/diagnóstico por imagem , Doença das Coronárias/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
10.
Cardiovasc Res ; 32(5): 830-8, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8944813

RESUMO

BACKGROUND: The cardioprotective effect of ischemic preconditioning has been hypothesized to occur through one or more signalling mechanisms which activate protein kinase C. Stimulation of alpha 1-adrenergic receptors by catecholamines released during the preconditioning episodes of ischemia is one of these putative signalling mechanisms. METHODS: To determine whether stimulation of alpha 1-adrenergic receptors before an ischemic challenge can mimic preconditioning, anesthetized dogs were treated with 4 intracoronary infusions of methoxamine HCl (10 micrograms/kg/min; n = 8), each 5 min in duration and followed by 5 min of washout. Control dogs (n = 10) were given similar infusions of 0.9% NaCl. A third group of dogs was preconditioned with 4 cycles of 5 min ischemia, each followed by 5 min of reperfusion (n = 8). All dogs then underwent 60 min of ischemia (circumflex coronary occlusion) followed by 3 h of reperfusion. Infarct size (expressed as % of area-at-risk) was measured with TTC macrochemistery and analyzed (using analysis of covariance [ANCOVA]) with respect to coronary collateral blood flow (measured using radioactive microspheres). RESULTS: Methoxamine markedly increased systemic arterial and left atrial pressures prior to but not during the ischemic challenge. Baseline predictors of infarct size were not different among the groups. Mean infarct size (adjusted from ANCOVA) did not differ between control and methoxamine-treated groups, 28.3 +/- 2.8% vs. 29.7 +/- 3.2%, respectively (P = NS), but was only 12.7 +/- 3.2% in the preconditioned group (P < 0.01 vs. control and methoxamine). CONCLUSIONS: A series of methoxamine infusions before an ischemic challenge did not affect infarct size. Thus, stimulation of alpha 1-adrenergic receptors alone is insufficient to mimic the cardioprotective effect of ischemic preconditioning in this canine model.


Assuntos
Agonistas alfa-Adrenérgicos/administração & dosagem , Precondicionamento Isquêmico Miocárdico , Metoxamina/administração & dosagem , Infarto do Miocárdio/prevenção & controle , Receptores Adrenérgicos alfa/efeitos dos fármacos , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Circulação Coronária/efeitos dos fármacos , Cães , Feminino , Infusões Intra-Arteriais , Masculino , Metoxamina/farmacologia , Estimulação Química
11.
Phys Rev Lett ; 85(12): 2474-7, 2000 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-10978085

RESUMO

Parametric Raman sideband generation is investigated using strongly driven Raman coherence in solid hydrogen. We show that the Raman coherence prepared with two coaxial single-mode lasers beats with multimode laser radiation with very broad bandwidth and efficiently replicates the broadband nature to the Raman sidebands without the restriction of phase matching. We demonstrate that this efficient replication occurs mainly on the negative side of Raman detuning, where the medium adiabatically follows the antiphased state.

12.
Carbohydr Res ; 224: 237-43, 1992 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-1591764

RESUMO

A beta-(1----6)-branched (1----3)-beta-D-glucan(AM-ASN) was isolated from the alkaline extract of the fruiting bodies of Amanita muscaria. AM-ASN had [alpha]D - 11 degrees in 0.5 M sodium hydroxide. Its estimated molecular weight was 95,000 in this alkaline solution and 260,000 in a neutral solution. The branches in the glucan were primarily single, (1----6)-linked D-glucopyranosyl groups, two for every seven residues in the (1----3)-linked main chain. AM-ASN exhibited significant antitumor activity against Sarcoma 180 in mice, and a mixture of AM-ASN with mitomycin C was more effective against the tumor than mitomycin C only.


Assuntos
Amanita/química , Antineoplásicos/química , Glucanos/química , Sarcoma Experimental/tratamento farmacológico , Animais , Antineoplásicos/farmacologia , Sequência de Carboidratos , Glucanos/isolamento & purificação , Glucanos/farmacologia , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Dados de Sequência Molecular , Monossacarídeos/análise
13.
Opt Lett ; 25(3): 177-9, 2000 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-18059821

RESUMO

We report a steady-state Raman gain measurement of the Q(1)(0) transition (v = 1 ? 0, J = 0 ? 0) in solid parahydrogen. We carry out measurements by pumping with a continuous-wave frequency-doubled YAG laser at 532 nm and observing the direct amplification of a probe-laser beam for the first Stokes transition at 683 nm. A large single-pass amplification coefficient of 2.3 +/- 0.2 is obtained at a pump intensity of 46 kW/cm(2), with an interaction length of 1 cm, giving a steady-state Raman gain coefficient of 18 +/- 3 cm/MW.

14.
Biol Pharm Bull ; 17(11): 1460-2, 1994 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-7703963

RESUMO

A water-insoluble, alkali-soluble, glucan (AM-APP), [alpha]D +160 degrees in 0.4 M NaOH, was isolated from the alkaline extract of the fruiting bodies of Amanita muscaria. The results of chemical and spectroscopic investigations indicate that AM-APP is a linear (1 --> 3)-alpha-D-glucan with a molecular weigh estimated by gel chromatography of about 42000. Its carboxymethylated product (AM-APP-CM) showed potent antitumor activity against sarcoma 180 in mice, although the native polysaccharide (AM-APP) had little effect. The distribution of carboxymethyl groups in the molecule was analyzed by gas chromatography and mass spectrometry. The degree of substitution of carboxymethyl groups was 0.95 and the substituents were located at O-2, at O-4, at O-6, at O-2 and O-6, and at O-4 and O-6 on glucose.


Assuntos
Amanita/metabolismo , Antineoplásicos/farmacologia , Polissacarídeos/isolamento & purificação , Sarcoma 180/tratamento farmacológico , Acetatos/química , Animais , Antineoplásicos/isolamento & purificação , Antineoplásicos/metabolismo , Antineoplásicos/uso terapêutico , Divisão Celular/efeitos dos fármacos , Cromatografia Gasosa , Cromatografia em Gel , Relação Dose-Resposta a Droga , Eletroforese em Gel de Poliacrilamida , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Masculino , Metilação , Camundongos , Peso Molecular , Polissacarídeos/metabolismo , Polissacarídeos/farmacologia
15.
Jpn Circ J ; 57(10): 1000-6, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8230671

RESUMO

The purpose of this study was to compare vascular damage and thrombus formation in the coronary and femoral arteries after balloon angioplasty, and to develop a physiological animal model of intracoronary occlusive thrombus using the balloon angioplasty technique. Angioplasty of the left anterior descending coronary arteries of 14 dogs was performed with an oversized balloon catheter at a high inflation pressure (150 PSI). This was followed angiographically (PTCA protocol). Dogs that showed arterial occlusion were divided into 2 groups. The dogs in 1 group were killed with an overdose of sodium pentobarbital, and those in the other group were infused with a tissue-type plasminogen activator (t-PA; 300,000 unit/kg). Angioplasty of the femoral and profunda femoris arteries (n = 5) was performed in 5 other dogs (PTA protocol). All of the animals were eventually sacrificed and tissue preparations were made from all 3 types of arteries. In the PTCA protocol, acute arterial occlusion was seen angiographically within 2 h in 10 of the 14 dogs. A histological study of the acutely occluded arteries (n = 5) showed thrombotic occlusion and severe arterial damage with medial tearing. T-PA was infused to 5 of the dogs with acute occlusion, and all showed reperfusion. A histological study of these animals showed severe arterial damage, but no macroscopic thrombus. In 4 dogs without acute occlusion, none of the 10 arteries examined were acutely occluded. In the PTA protocol, none of the 10 arteries were acutely occluded. A histological study showed fewer thrombi and less severe arterial damage.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Angioplastia Coronária com Balão , Angioplastia com Balão , Trombose Coronária/patologia , Vasos Coronários/patologia , Artéria Femoral/patologia , Animais , Angiografia Coronária , Trombose Coronária/etiologia , Modelos Animais de Doenças , Cães , Masculino
16.
Acta Neurol Scand ; 84(5): 448-51, 1991 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1776394

RESUMO

A 69-year-old woman presented a transient cerebral ischemic attack, showing left arm weakness and slurred speech which recovered within 4 h of onset, while computed tomography indicated a putaminal hemorrhage. The regional cerebral blood flow distribution, measured semiquantitatively by use of 123I amphetamine emission tomography, was disturbed, which persisted more than one month up to a maximum of 4.5 months from the onset of symptoms. This case illustrates a variety of putaminal hemorrhage of good functional and vital prognosis, and provides an example in which the regional cerebral blood flow disturbances might persist for more than one month up to 4.5 months after the occurrence of a transient ischemic attack caused by a putaminal hemorrhage.


Assuntos
Hemorragia Cerebral/diagnóstico por imagem , Ataque Isquêmico Transitório/diagnóstico por imagem , Putamen/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único , Idoso , Anfetaminas , Gânglios da Base/irrigação sanguínea , Córtex Cerebral/irrigação sanguínea , Feminino , Humanos , Radioisótopos do Iodo , Iofetamina , Putamen/irrigação sanguínea , Fluxo Sanguíneo Regional/fisiologia
17.
J Cardiogr ; 16(4): 1027-37, 1986 Dec.
Artigo em Japonês | MEDLINE | ID: mdl-3429900

RESUMO

An interesting case of right and left coronary arteries-right atrial fistulas diagnosed by Doppler echocardiography was presented. A 59-year-old woman was referred for evaluation of her continuous murmur. A thrill was palpable at the left sternal border in the third intercostal space. The proximal portions of the dilated right and left coronary arteries and distal portions of the tortuous and converging fistulas of both coronary arteries were imaged by two-dimensional echocardiography. Bidirectional continuous turbulent Doppler signals were detected in the proximal portions of the dilated right and left coronary arteries, in the distal portions of the fistulas around the crux and in the right atrium. These findings facilitated our diagnosis of right and left coronary arteries-right atrial fistulas. The flow velocity at the ostium of the right coronary artery was highest and nearly the same as the flow velocity (about 2 m/s) obtained by continuous wave Doppler from the maximum point of the thrill. The maximum pressure difference was considered located at this portion. Selective coronary angiography confirmed the right coronary artery and left main trunk-left circumflex coronary artery to be large, elongated and tortuous. These fistulas were communicating with the right atrium. This case demonstrates the usefulness of Doppler echocardiography in the noninvasive diagnosis of coronary arteriovenous fistula.


Assuntos
Malformações Arteriovenosas/diagnóstico , Anomalias dos Vasos Coronários/diagnóstico , Ecocardiografia/métodos , Átrios do Coração/anormalidades , Cateterismo Cardíaco , Angiografia Coronária , Feminino , Humanos , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
18.
J Cardiol ; 18(1): 251-7, 1988 Mar.
Artigo em Japonês | MEDLINE | ID: mdl-3221315

RESUMO

This is a case report presenting interesting findings on two-dimensional and Doppler echocardiograms due to multiple pulmonary thromboses. A 67-year-old woman had a history of surgery for colon polyps in August, 1986. After surgery, she suffered from tachycardia and dyspnea, and was admitted to our hospital because of a loss of consciousness. Sinus tachycardia, complete right bundle branch block and T-wave inversion in leads III, aVF and V1-4 were observed on her electrocardiogram. Cardiomegaly was noted on her chest radiograph. On the third hospital day, echocardiography was performed. On two-dimensional echocardiography, marked right ventricular dilatation with hypokinesis of the wall, and a flattened interventricular septum were observed on the short-axis view, and M-mode echocardiograms showed disappearance of the E wave and delay of the opening of the tricuspid valve, resulting in a monophasic triangular pattern. Doppler echocardiography showed the tricuspid valve flow to be delayed, mainly observed during atrial systole. These findings indicate decreased right ventricular compliance. The patient died on the 6th hospital day, and multiple new and old thrombi were found in the pulmonary artery at autopsy.


Assuntos
Morte Súbita , Ecocardiografia Doppler , Ecocardiografia , Embolia Pulmonar/diagnóstico , Idoso , Feminino , Humanos , Pulmão/diagnóstico por imagem , Embolia Pulmonar/mortalidade , Embolia Pulmonar/patologia , Radiografia
19.
Circulation ; 88(1): 223-34, 1993 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8319337

RESUMO

BACKGROUND: It has been reported that a brief period of coronary occlusion and reperfusion slows the rate of ATP depletion during subsequent sustained ischemia as well as limiting infarct size. However, it has not yet been determined whether ischemic preconditioning also has an effect on the functional and metabolic recovery of stunned myocardium. Our study was designed to address this problem. METHODS AND RESULTS: Farm pigs were anesthetized with fluothane and randomly assigned to either a control group or a preconditioned group. The control group (n = 15) underwent 15 minutes of coronary occlusion followed by 120 minutes of reperfusion. The preconditioned group (n = 14) underwent two episodes of 5-minute occlusion and 5-minute reperfusion followed by 15 minutes of occlusion and 120 minutes of reperfusion. This protocol was designed to exclude the stunning effect of the preconditioning procedure itself as much as possible besides preconditioning the heart. A pair of ultrasonic crystals was implanted in the area at risk perfused by the left anterior descending coronary artery. 31P-nuclear magnetic resonance spectroscopy and sonomicrometry were performed alternately. Regional myocardial blood flow (RMBF) was determined with colored microspheres. At 15 minutes of sustained ischemia, phosphocreatine (Pcr), ATP, and intracellular pH were significantly better preserved in the preconditioned group (Pcr: control/preconditioned, 1 +/- 1%/14 +/- 1%; ATP:control/preconditioned, 66 +/- 2%/74 +/- 2%; pH:control/preconditioned, 6.32 +/- 0.07/6.52 +/- 0.05; P < .05). After reperfusion, ATP increased progressively and was almost normalized at 120 minutes of reperfusion in the preconditioned group (control/preconditioned, 73 +/- 4%/95 +/- 3%; P < .05). Overshoot of Pcr (which indicates that the energy generating system is operating better than energy utilizing system) persisted in preconditioned hearts but disappeared rapidly in controls (control/preconditioned, 104 +/- 3%/130 +/- 3% after 120 minutes of reperfusion). There was no significant difference in percent segment shortening (%SS), RMBF, and hemodynamics between the two groups throughout the experiment (%SS: control/preconditioned, 29.8 +/- 5.9%/28.8 +/- 6.3% of baseline after 120 minutes of reperfusion). CONCLUSIONS: Preconditioning improves energy metabolism during reperfusion, although it does not attenuate myocardial stunning for at least 2 hours after reperfusion.


Assuntos
Circulação Coronária/fisiologia , Contração Miocárdica/fisiologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miocárdio/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Constrição , Vasos Coronários/fisiologia , Metabolismo Energético/fisiologia , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Fosfocreatina/metabolismo , Suínos , Fatores de Tempo , Função Ventricular Esquerda/fisiologia
20.
Heart Vessels ; 12(4): 157-66, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9559965

RESUMO

The purpose of the present study was to investigate the responses of the cytoskeleton and the presence of apoptosis following acute damage of medial smooth muscle cells after percutaneous transluminal coronary angioplasty (PTCA). We killed 20 dogs, 4h and 4 days after PTCA (n=10 in each group). Ten dogs without PTCA were used as controls. PTCA was achieved by inflating balloon catheters two times, for 60s each time, to 150 PSI, followed by a 60-s deflation. The coronary artery obtained from each dog was fixed in 10% formalin neutral buffer solution. The response of the cytoskeleton was studied immunohistochemically. using monoclonal antibodies against alpha-smooth muscle actin, vimentin, and beta-tubulin. Proliferation was determined by proliferating cell nuclear antigen (PCNA), and DNA fragmentation indicating apoptosis was determined by in situ nick end labeling. Four h after PTCA, endothelial denudation, microscopic mural thrombi, rupture of the internal elastic membrane, medial tear, and stretched smooth muscle cells with nuclei were found at the PTCA site. An immunohistochemical study revealed diffuse reduction or defective immunoreactivity in each cytoskeleton of medial smooth muscle cells, 4h after PTCA. The extent of positive immunoreactivity in the media decreased to 45+/-11% in alpha-smooth muscle actin (control value, 80+/-10%), 9+/-8% in vimentin (control value, 83+/-9%), and 10+/-7% in beta-tubulin (control value, 75+/-8%). The decrease was more significant in vimentin and beta-tubulin than in alpha-smooth muscle actin. Four days after PTCA, the features were diffuse cell death and the focal proliferation of medial cells, as well as macroscopic intramural thrombi. The extent of positive immunoreactivity in the media was 15+/-9% in alpha-smooth muscle actin, 13+/-7% in vimentin, and 14+/-11% in beta-tubulin. There were no smooth muscle cells with positive PCNA (0%) in the control and 4-h groups, but 4 days after PTCA the percentage was 19+/-4%. In situ nick end labeling showed DNA fragmentation in the nuclei of medial smooth muscle cells at a rate of 15+/-5% 4h after PTCA and at 8+/-6% 4 days after PTCA, compared with 0% in the control. We concluded that severe damage of the cytoskeleton and medial smooth muscle cell death were induced immediately after PTCA, followed by proliferation of smooth muscle cells. Apoptosis may be partially involved in the death of smooth muscle cells, in addition to necrosis. Damage to the cytoskeleton and apoptosis may play an important role in the pathogenesis of acute lesions and the proliferation of smooth muscle cells after PTCA.


Assuntos
Angioplastia Coronária com Balão , Apoptose , Vasos Coronários/citologia , Citoesqueleto , Músculo Liso Vascular/citologia , Animais , Divisão Celular , Vasos Coronários/patologia , Citoesqueleto/patologia , Cães , Imuno-Histoquímica , Músculo Liso Vascular/patologia
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