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1.
Energy Sustain Soc ; 12(1): 50, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36589223

RESUMO

Background: Applying the Multi-Level Perspective (MLP) on socio-technical transitions, paired with the interdisciplinary framing approach, this paper investigates how incumbent actors of automobility in Germany framed the issue of a "transition of mobility and transport" ("Verkehrs/Mobilitätswende") in their public communication in 2020. We first identified representatives of industry, science, policy, and media, since the Verkehrs/Mobilitätswende and its implementation measures are contested among these actors. Employing qualitative content analysis, we then screened 325 public documents according to the elements of the framing approach problem definition, causal interpretation, moral evaluation, and treatment recommendation. Results: Findings show that most of the actors frame a transformation of transport and mobility as a necessity. Their arguments encompass environmental and climate-related issues as well as infrastructural problems for bikes and public transport caused by the hegemony of automobility. The actors propose a variety of solutions, primarily focusing on technical innovations for cars or on the expansion of different infrastructures to achieve a modal shift towards sustainable mobility. Conclusion: This paper demonstrates that there is no common understanding of the problems and solutions to foster a mobility transition, as the diversity of problems and solutions proposed within the frame elements is high and complicates the prevailing implementation gap of the mobility transition. Therefore, MLP should be conceptually and methodologically bridged with the interdisciplinary framing approach, particularly with regard to the transition of mobility and transport.

2.
Phys Rev Lett ; 107(27): 276601, 2011 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-22243321

RESUMO

We observe photocurrents induced in single-layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left to right handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory based on Boltzmann's kinetic equation is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.

3.
Anaesthesist ; 57(12): 1167-71, 2008 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-18726078

RESUMO

BACKGROUND: The presence of multiple blood clots in leucocyte-depleted erythrocyte concentrates during a transfusion gave rise to an investigation to find the exact cause. MATERIALS AND METHODS: Determination of the various blood group systems was carried out using the gel centrifugation method and also the polymerase chain reaction (PCR) using sequence-specific primers. In addition the human leucocyte antigens (HLA) class 1 and class 2 markers were determined with molecular biological methods. RESULTS: The erythrocytes in the blood bags containing the blood clots showed a mixed-field agglutination in each blood group where the donor and recipient had different phenotypes. The HLA groups, however, could be solely attributed to the patient, since during the preparation of erythrocyte concentrates all leucocytes are removed and only very few residual cells containing DNA are present. CONCLUSIONS: To the best of our knowledge, this is the first detailed report on blood clots from patient blood in erythrocyte concentrates, which occurred during a transfusion. The retrograde filling of the blood bag with patient blood during the transfusion led to coagulation in the bag. Therefore, careful attention must be taken when dealing with stored blood and corresponding training must be regularly carried out.


Assuntos
Coagulação Sanguínea , Transfusão de Eritrócitos/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Aglutinação , Antígenos de Grupos Sanguíneos , Perda Sanguínea Cirúrgica , Centrifugação , DNA/sangue , Primers do DNA , Genes MHC Classe I/genética , Genes MHC da Classe II/genética , Marcadores Genéticos , Humanos , Complicações Intraoperatórias/terapia , Leucócitos , Masculino , Embalagem de Produtos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
4.
Technol Cancer Res Treat ; 6(4): 321-8, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17668940

RESUMO

To describe the technological background, the accuracy, and clinical feasibility for single session lung radiosurgery using a real-time robotic system with respiratory tracking. The latest version of image-guided real-time respiratory tracking software (Synchrony, Accuray Incorporated, Sunnyvale, CA) was applied and is described. Accuracy measurements were performed using a newly designed moving phantom model. We treated 15 patients with 19 lung tumors with robotic radiosurgery (CyberKnife, Accuray) using the same treatment parameters for all patients. Ten patients had primary tumors and five had metastatic tumors. All patients underwent computed tomography-guided percutaneous placement of one fiducial directly into the tumor, and were all treated with single session radiosurgery to a dose of 24 Gy. Follow up CT scanning was performed every two months. All patients could be treated with the automated robotic technique. The respiratory tracking error was less than 1 mm and the overall shape of the dose profile was not affected by target motion and/or phase shift between fiducial and optical marker motion. Two patients required a chest tube insertion after fiducial implantation because of pneumothorax. One patient experienced nausea after treatment. No other short-term adverse reactions were found. One patient showed imaging signs of pneumonitis without a clinical correlation. Single-session radiosurgery for lung tumor tracking using the described technology is a stable, safe, and feasible concept for respiratory tracking of tumors during robotic lung radiosurgery in selected patients. Longer follow-up is needed for definitive clinical results.


Assuntos
Neoplasias Pulmonares/cirurgia , Radiocirurgia/instrumentação , Robótica , Software , Cirurgia Assistida por Computador/instrumentação , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Fatores de Tempo , Resultado do Tratamento
5.
Int J Obstet Anesth ; 27: 85-8, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27378710

RESUMO

Stiff person syndrome is a rare neurologic disorder with an estimated incidence of 1:1000000. The underlying pathophysiology is truncal and proximal limb muscle stiffness resulting from continuous co-contracture of agonist and antagonist muscle groups concomitant with superimposed episodic muscle spasms. Loss of gamma-aminobutyric acid-mediated inhibition creates chronic excitation manifested by tonic agonist-antagonist muscle contraction. To date, only three case reports referred indirectly to the anesthetic management of parturients with Stiff person syndrome. The authors describe their management of a parturient with Stiff person syndrome who underwent urgent cesarean delivery under epidural anesthesia.


Assuntos
Anestesia Epidural/métodos , Anestesia Obstétrica/métodos , Cesárea , Rigidez Muscular Espasmódica/complicações , Adulto , Emergências , Feminino , Humanos , Gravidez
6.
Vet Microbiol ; 77(1-2): 99-108, 2000 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11042403

RESUMO

In the study three groups with five pregnant sows each were used. The animals were vaccinated twice, 2 weeks apart, in different stages of gestation, i.e. +/-4, +/-8 and +/-12 weeks after insemination and then 14 days later, respectively. From each group of sows three litters were randomly selected and vaccinated twice, 4 weeks apart, at 5 and 9, 7 and 11, and 9 and 13 weeks of life, respectively. Blood for serological investigations by virus neutralisation test and ELISA tests (for E(rns) antibodies and for E2 antibodies, separately) was taken before immunisation, at each vaccination and 2 weeks thereafter. Clinical observations shown that no local nor systemic reactions as well as no adverse effect on gestation occurred after vaccinations in any of the sows. Serological tests detected a low level of antibodies after the first vaccination and a typical booster effect after the second one. In piglets no adverse effect of the vaccination on the body weight gain was found. The presence of maternally derived antibodies (MDA) in non-vaccinated control piglets was observed up to the age of 5-13 weeks of life. The most evident immunological reaction was obtained in piglets vaccinated at the age of 5 or 7 weeks of life and revaccinated 4 weeks later. The CSFV-E2 subunit marker vaccine tested proved to be safe for pregnant sows and immunogenic for MDA positive piglets.


Assuntos
Vírus da Febre Suína Clássica/imunologia , Peste Suína Clássica/prevenção & controle , Vacinação/veterinária , Animais , Anticorpos Antivirais/análise , Feminino , Gravidez , Suínos , Proteínas do Envelope Viral/imunologia
7.
Vet Microbiol ; 77(1-2): 83-97, 2000 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11042402

RESUMO

The efficacy of the classical swine fever (CSF) subunit marker vaccine Porcilis Pesti based on baculovirus expressed envelope glycoprotein E2 of CSF virus (CSFV) was evaluated in pregnant sows. Ten gilts were vaccinated with one dose of marker vaccine, followed by a second dose 4 weeks later. Four gilts remained unvaccinated and received a placebo at the same times. Thirty-three days after the second vaccination all animals were artificially inseminated. Neither local or systemic reactions nor an increase of body temperature were observed after vaccinations. All gilts showed a normal course of pregnancy. Thirty-five days after first vaccination all animals developed E2 specific neutralising antibodies with titres in the range of 5.0 and 7.5 log(2). No antibodies to CSFV-E(rns) were found in ELISA. On day 65 of gestation (126 days after the first immunisation) all sows were infected intranasally using 2ml (10(6.6) TCID(50)/ml) of the low virulent CSFV strain "Glentorf". After challenge in two of the unvaccinated control sows a slight transient increase of body temperature was observed, whereas leukopenia was demonstrated in all control animals. In addition all controls became viraemic. Vaccinations with the CSFV subunit vaccine protected the animals from clinical symptoms of CSF. In two sows a moderate decrease of leukocyte counts was detected on day 5 post infection. In contrast to the unvaccinated control sows in none of the vaccinated animals virus was isolated from the nasal swabs or the blood. Approximately 40 days after challenge all sows were killed and necropsy was done. The sows and their offspring were examined for the presence of CSFV in blood, bone marrow and different organs. No virus was found in any of the sows. In contrast, in all litters of the control sows CSFV was found in the blood as well as in the organ samples. Nine out of 10 litters of the vaccinated sows were protected from CSFV infection. Blood samples, lymphatic organs and bone marrow of these animals were all virologically negative. When sera were tested for CSFV-antibodies all sows had developed E(rns)-specific antibodies but no CSFV-specific antibodies were found in any of the progeny. It was concluded that vaccination with CSF subunit marker vaccine Porcilis((R)) Pesti protected 90% of the litters from viral infection when sows were challenged mid-gestation using the CSFV-strain "Glentorf".


Assuntos
Vírus da Febre Suína Clássica/imunologia , Peste Suína Clássica/prevenção & controle , Transmissão Vertical de Doenças Infecciosas/veterinária , Vacinação/veterinária , Vacinas Virais , Animais , Biomarcadores , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Gravidez , Suínos , Eliminação de Partículas Virais
8.
Nat Nanotechnol ; 8(2): 104-7, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23334170

RESUMO

A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations. This so-called ratchet effect has fascinating ramifications in engineering and natural sciences. Graphene is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.

9.
Z Orthop Unfall ; 150(3): 309-17, 2012 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-22354443

RESUMO

BACKGROUND: The results of a national survey from 1998 showed that only around 10 % of orthopaedic surgeons in Germany had strictly implemented modern third-generation cementing techniques in total hip arthroplasty (THA). A 2005 update showed an improvement up to 29.4 %. The study was repeated in 2010 in order to evaluate the current situation and to determine whether modern cementing techniques have become more popular. MATERIAL AND METHODS: A detailed, slightly modified questionnaire regarding cement and bone preparation, cementing techniques on acetabulum and femur, and implant types was sent to 492 German orthopaedic and trauma hospitals, as well as to visiting surgeons with an interest in THA. The survey was conducted over 6 months. The response rate was 51.8 %, 255 questionnaires were available for evaluation and statistical analysis. RESULTS: Palacos R+G bone cement remained the most widely used cement (52.2 %). The mixing times given varied significantly. Vacuum mixing systems have again become more popular (85.2 %). In the femur 78.6 % of the surgeons attempted to preserve cancellous bone and 77.8 % used pulsatile (jet) lavage. Retrograde cement application via a cement gun was done in 85.8 %. Cement restrictors were used in more than 98 %. Only 72.7 % of the surgeons implemented sustained cement pressurisation and preferred a cement mantle thickness over 2 mm (55.2 %). Only 18.1 % drilled multiple small acetabular keyholes and 66.5 % used jet lavage. In 67.9 % no cement gun was used and in 70.7 % the cement was applied at high viscosity. Cement pressurisation was done manually in 89.1 %. The Müller straight stem device remained the most popular implant. Only 7.4 % of the centres implanted less than 20 and 40.3 % more than 100 cemented stems per year, whereby higher THA volumes correlated with better cementing technique. CONCLUSION: The results of this survey demonstrate that, in comparison to 2005, the current state of cemented THA, in particular cementing technique has generally significantly improved. Future emphasis should focus on continued surgeon education and training, as the cementing techniques are of utmost importance for long-term durability.


Assuntos
Artroplastia de Quadril/métodos , Artroplastia de Quadril/estatística & dados numéricos , Cimentos Ósseos/uso terapêutico , Cimentação/estatística & dados numéricos , Padrões de Prática Médica/estatística & dados numéricos , Alemanha/epidemiologia , Humanos
10.
Vet Rec ; 166(3): 70-4, 2010 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-20081177

RESUMO

Three vaccination challenge studies were performed to evaluate the impact on vaccine efficacy of combining porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae vaccines. Piglets were vaccinated with either a M hyopneumoniae bacterin, a modified live PRRSV vaccine based on a European-type PRRSV strain, or a combination of both vaccines, followed by experimental infection with either M hyopneumoniae or PRRSV. Vaccine efficacy was evaluated by assessing lung lesion scores for M hyopneumoniae and measuring viraemia for PRRSV. There were no significant differences between the protective efficacy of the combined vaccine protocol and the protective efficacy of the two single vaccines, indicating that PRRSV vaccination did not interfere with M hyopneumoniae vaccine efficacy and vice versa.


Assuntos
Vacinas Bacterianas/administração & dosagem , Mycoplasma hyopneumoniae/imunologia , Pneumonia Suína Micoplasmática/prevenção & controle , Síndrome Respiratória e Reprodutiva Suína/prevenção & controle , Vírus da Síndrome Respiratória e Reprodutiva Suína/imunologia , Vacinas Virais/administração & dosagem , Animais , Animais Recém-Nascidos , Distribuição Aleatória , Organismos Livres de Patógenos Específicos , Suínos , Resultado do Tratamento , Vacinas Atenuadas , Vacinas Combinadas
14.
Vaccine ; 22(31-32): 4183-90, 2004 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-15474708

RESUMO

The aim of this study was to find out how efficiently pigs that are vaccinated with an attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine based on a virus from the Lelystad cluster are protected against a European wild-type strain from the same or another genetic cluster. Two experiments were performed. In each experiment, 5-week-old PRRSV-seronegative pigs were vaccinated intramuscularly with 10(4.5) TCID50 of a commercial vaccine based on a European virus strain from the Lelystad cluster. Non-vaccinated pigs were included as controls. At 5, 9, 15, 20, 28, 35 and 42 days post vaccination (PV), broncho-alveolar lavage (BAL) fluids and blood were collected to determine vaccine virus quantities. Forty-nine days PV, pigs were challenged intranasally with 10(6.0) TCID50 of a European wild-type strain, belonging either to the Lelystad cluster (98% nucleotide identity in ORF5 with vaccine strain) (experiment A) or to an Italian cluster (84% nucleotide identity in ORF5 with vaccine strain) (experiment B). At 5, 9, 15, 20 and 27 days post challenge (PC), BAL fluids and blood were collected to determine virus quantities. Vaccine virus was first detected in BAL fluids and blood at 5 days PV and reached highest quantities between 9 and 15 days PV. One pig was positive in its BAL fluid until 42 days PV. After challenge, virus was isolated from BAL fluids and blood of all non-vaccinated control pigs. All vaccinated pigs challenged with the Lelystad strain remained negative for virus, while virus was present in BAL fluids and blood of all vaccinated pigs after challenge with the Italian strain. Mean virus titres of the vaccinated pigs challenged with the Italian strain were significantly lower than those of the non-vaccinated control pigs (P <0.05) at 9, 15 and 20 days PC. Thus, the genetic diversity within European-type PRRSV may affect the efficacy of the current European-type vaccines.


Assuntos
Vírus da Síndrome Respiratória e Reprodutiva Suína/genética , Vírus da Síndrome Respiratória e Reprodutiva Suína/imunologia , Suínos/imunologia , Vacinas Virais/genética , Vacinas Virais/imunologia , Animais , Líquido da Lavagem Broncoalveolar/citologia , Europa (Continente) , Síndrome Respiratória e Reprodutiva Suína/imunologia , Síndrome Respiratória e Reprodutiva Suína/prevenção & controle , Síndrome Respiratória e Reprodutiva Suína/virologia , Vacinação , Replicação Viral
15.
Anesth Analg ; 88(3): 625-32, 1999 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10072018

RESUMO

UNLABELLED: The sedative and anesthetic-sparing ability of the alpha2-adrenergic agonist dexmedetomidine is well documented. In this study, we identified the effects of halothane, with and without dexmedetomidine, on hemodynamic and electroencephalographic (EEG) variables and quantified the concentration of halothane resulting in various anesthetic depth indices mediated through the central nervous system (CNS) in chronically instrumented cats. Halothane was given alone or after dexmedetomidine (15 microg/kg p.o.). In both groups, four indices of anesthetic depth--minimum alveolar anesthetic concentration (MAC; no movement to noxious stimuli), MAC(BAR) (no autonomic response to noxious stimuli), MAC(BS) (EEG burst suppression), and MAC(ISOELECTRIC) (EEG isoelectricity)--were determined. Halothane decreased arterial blood pressure, heart rate, and higher frequency components of the EEG before the onset of burst suppression and isoelectricity. Dexmedetomidine pretreatment augmented the actions of halothane on arterial pressure, heart rate, and the EEG. Dexmedetomidine reduced the halothane concentrations resulting in MAC (from 1.22% +/- 0.06% to 0.89% +/- 0.08%) and MAC(BAR) (from 1.81% +/- 0.05% to 1.1% +/- 0.10%), but not those resulting in MAC(BS) (3.01% +/- 0.17% vs 3.14% +/- 0.10%) or MAC(ISOELECTRIC) (4.39% +/- 0.26% vs 4.65% +/- 0.12%). These results suggest that dexmedetomidine does not alter various CNS-mediated indices of anesthetic action to equivalent degrees and that there are dissimilar degrees of an anesthetic-sparing action at different levels of the neuraxis. IMPLICATIONS: The anesthetic adjuvant dexmedetomidine seems to differentially alter central nervous system-mediated indices of anesthetic action. Lower brainstem or spinal determinants of anesthetic depth (movement and hemodynamic responses) are more attenuated than those of higher brain functions, such as the electroencephalogram.


Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Anestésicos Inalatórios/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Halotano/farmacologia , Imidazóis/farmacologia , Agonistas alfa-Adrenérgicos/farmacocinética , Anestésicos Inalatórios/farmacocinética , Animais , Pressão Sanguínea/efeitos dos fármacos , Gatos , Combinação de Medicamentos , Eletroencefalografia/efeitos dos fármacos , Feminino , Halotano/farmacocinética , Frequência Cardíaca/efeitos dos fármacos , Imidazóis/farmacocinética , Masculino , Medetomidina , Alvéolos Pulmonares/metabolismo
16.
Anesthesiology ; 91(5): 1462-9, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10551599

RESUMO

BACKGROUND: Cerebral ischemia and hypoxia may cause injury to both neuronal and vascular tissue. The direct effects of hypoxia on endothelial function in intraparenchymal cerebral arterioles are unknown. Using a modification of the rat brain slice preparation, allowing continuous imaging of these previously inaccessible vessels, microvessel dilation was evaluated before and after a brief hypoxic episode. METHODS: Rat brain slices were superfused with oxygenated artificial cerebrospinal fluid. Hippocampal arterioles were visualized using computerized videomicroscopy, and their diameters (range, 12-27 microm) were measured using image analysis. After preconstriction with prostaglandin F2alpha and controlled pH and carbon dioxide tension, graded concentrations of either acetylcholine (endothelium-dependent vasodilation) or sodium nitroprusside (endothelium-independent vasodilation) were given before and after a 10-min period of hypoxia. RESULTS: Sodium nitroprusside (100 microM) caused similar dilation before and after hypoxia (mean +/- SEM: 9.6 +/- 0.6% vs. 13.0 +/- 0.9%). Acetylcholine (100 microM) caused significantly less dilation (P < 0.05) after hypoxia (mean +/- SEM: 9.3 +/- 1.8% vs. 3.6 +/- 1.2%). The decreased acetylcholine-induced dilation after hypoxia was not reversed by pretreatment with L-arginine (1 mM), the precursor of nitric oxide (mean +/- SEM: 8.8 +/- 1.3% vs. 4.4 +/- 0.7%). CONCLUSIONS: Even brief periods of hypoxia may cause endothelial dysfunction in intraparenchymal cerebral arterioles. This does not seem to be related to a deficiency of the nitric oxide substrate, L-arginine. Endothelial dysfunction and impaired endothelium-dependent dilation of microvessels may decrease oxygen delivery and increase neuronal injury during cerebral hypoxia-reoxygenation.


Assuntos
Endotélio Vascular/fisiologia , Hipocampo/fisiopatologia , Hipóxia-Isquemia Encefálica/fisiopatologia , Acetilcolina/farmacologia , Animais , Arteríolas/efeitos dos fármacos , Gasometria , Hipocampo/irrigação sanguínea , Técnicas In Vitro , Masculino , Microcirculação , Nitroprussiato/farmacologia , Ratos , Ratos Sprague-Dawley , Vasodilatadores/farmacologia
17.
Anesthesiology ; 92(1): 125-32, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10638908

RESUMO

BACKGROUND: The causes of volatile anesthetic-induced cerebral vasodilation include direct effects on smooth muscle and indirect effects via changes in metabolic rate and release of mediators from vascular endothelium and brain parenchyma. The role of nitric oxide and the relative importance of neuronal and endothelial nitric oxide synthase (nNOS and eNOS, respectively) are unclear. METHODS: Rat brain slices were superfused with oxygenated artificial cerebrospinal fluid. Hippocampal arteriolar diameters were measured using computerized videomicrometry. Vessels were preconstricted with prostaglandin F2alpha (PGF2alpha; halothane group) or pretreated with 7-nitroindazole sodium (7-NINA, specific nNOS inhibitor, 7-NINA + halothane group) or N-nitro-L-arginine methylester (L-NAME; nonselective NOS inhibitor, L-NAME + halothane group) and subsequently given PGF2alpha to achieve the same total preconstriction as in the halothane group. Increasing concentrations of halothane were administered and vasodilation was calculated as a percentage of preconstriction. RESULTS: Halothane caused significant, dose-dependent dilation of hippocampal microvessels (halothane group). Inhibition of nNOS by 7-NINA or nNOS + eNOS by L-NAME similarly attenuated halothane-induced dilation at 0.6, 1.6, and 2.6% halothane. The dilation (mean +/- SEM) at 1.6% halothane was 104 +/- 10%, 65 +/- 6%, and 51 +/- 9% in the halothane, 7-NINA + halothane and L-NAME + halothane groups, respectively. The specificity of 7-NINA was confirmed by showing that acetylcholine-induced dilation was not inhibited by 7-NINA but was converted to constriction by L-NAME. CONCLUSIONS: At clinically relevant concentrations, halothane potently dilates intracerebral arterioles. This dilation is mediated, in part, by neuronally derived nitric oxide. Endothelial NOS does not play a major role in halothane-induced dilation of hippocampal microvessels.


Assuntos
Anestésicos Inalatórios/farmacologia , Encéfalo/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Halotano/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/farmacologia , Óxido Nítrico/fisiologia , Análise de Variância , Animais , Circulação Cerebrovascular/efeitos dos fármacos , Interações Medicamentosas , Indazóis/farmacologia , Masculino , Microcirculação/efeitos dos fármacos , Óxido Nítrico Sintase/antagonistas & inibidores , Ratos , Ratos Sprague-Dawley , Vasodilatação/efeitos dos fármacos
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