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1.
Phys Chem Chem Phys ; 25(37): 25552-25565, 2023 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-37718648

RESUMO

NiOx films grown from 50 nm thick Ni on Si(111) were put in contact with oxygen and subsequently water vapor at elevated temperatures. Near ambient pressure (NAP)-XPS and -XAS reveal the formation of oxygen vacancies at elevated temperatures, followed by H2O dissociation and saturation of the oxygen vacancies with chemisorbing OH. Through repeated heating and cooling, OH-saturated oxygen vacancies act as precursors for the formation of thermally stable NiOOH on the sample surface. This is accompanied by a significant restructuring of the surface which increases the probability of NiOOH formation. Exposure of a thin NiOx film to H2O can lead to a partial reduction of NiOx to metallic Ni accompanied by a distinct shift of the NiOx spectra with respect to the Fermi edge. DFT calculations show that the formation of oxygen vacancies and subsequently Ni0 leads to a state within the band gap of NiO which pins the Fermi edge.

2.
Nervenarzt ; 90(3): 293-298, 2019 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-30143832

RESUMO

BACKGROUND: The German Law for the Development of Care and Funding for Psychiatric and Psychosomatic Services (PsychVVG) has established a new regulation for the mental healthcare system. In the future, characteristics of hospitals and catchment areas will be an elementary part of negotiations on remuneration. OBJECTIVE: The aim of this study was to identify structural and regional characteristics of psychiatric hospitals in Germany that contribute to increased average costs according to the views of clinical managers and directors. METHODS: In this study 37 guided expert interviews were conducted with business managers, financial controllers, leading medical and nursing personnel from psychiatric hospitals and the characteristics relevant for the budget and increased average costs were collated. RESULTS: Important factors with top priority were hospital infrastructure, characteristics of the catchment area and specialties of inpatient services provided. Obligatory service for a defined catchment area, increased documentation requirements and infrastructure of buildings and grounds were estimated as being associated with the highest additional financial expenditure. CONCLUSION: It is a challenge for clinics to prove increased average costs due to the respective hospital structural and regional characteristics. This study shows which characteristics should be considered as most cost-relevant from the perspective of hospital management.


Assuntos
Orçamentos , Hospitais Psiquiátricos , Custos e Análise de Custo , Alemanha , Hospitais Psiquiátricos/economia , Hospitais Psiquiátricos/organização & administração , Hospitais Psiquiátricos/estatística & dados numéricos , Humanos
3.
Nervenarzt ; 90(1): 40-44, 2019 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-30238232

RESUMO

The objective of this study was to systematically review the international literature with respect to significant links between staffing levels or qualification on the one hand and patient-related outcomes on the other. Of the initial 7778 abstracts identified by means of a complex search strand in PubMed and CINAHL, 51 could finally be included in a qualitative synthesis. A total of nine different patient-related outcome categories with significant associations on an at least ordinally scaled level were distinguished. None of the studies included had a (quasi-)experimental research design. Despite, in some instances, high numbers of cases at multiple sites and efforts to control obvious confounding variables by regression analysis, no evidence-based conclusions for health policy or clinical practice can be drawn from the available observational studies. There is therefore a considerable need for prospective randomized or at least quasi-experimental studies also as accompanying research on novel models of financing.


Assuntos
Resultado do Tratamento , Recursos Humanos , Humanos , Estudos Prospectivos , Recursos Humanos/estatística & dados numéricos
5.
Nervenarzt ; 89(7): 814-820, 2018 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-29679128

RESUMO

The aim of this pilot study was to estimate the share of working time that staff in psychiatric hospitals theoretically spend on obligatory activities, such as training and further education, organizational and documentation tasks as well as statutory lecturing duties without patient contact. A total of 47 physicians, 39 nurses, 34 psychologists and 35 social workers from eight psychiatric hospitals were interviewed. The results reveal that the theoretically remaining time for direct patient contact is low. The ratio of time spent with versus time spent without patient contact was even worse for senior physicians and leading nurses as well as part-time employees; however, all activities without direct contact to patients seemed to be indispensable in terms of quality of treatment and care. Hence, employees in German psychiatric hospitals regularly have to make decisions on which of their duties they prefer to neglect, to which they are actually obligated.


Assuntos
Hospitais Psiquiátricos , Médicos , Documentação , Hospitais Psiquiátricos/economia , Hospitais Psiquiátricos/estatística & dados numéricos , Humanos , Entrevistas como Assunto , Projetos Piloto
6.
Polymers (Basel) ; 10(6)2018 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-30966618

RESUMO

Diphenyl guanidine (DPG) is an essential ingredient in silica-reinforced rubber compounds for low rolling resistance tires, as it not only acts as a secondary accelerator, but also as a catalyst for the silanization reaction. However, because of concern over the toxicity of DPG that liberates aniline during high-temperature processing, safe alternatives are required. The present work studies several amines as potential alternatives for DPG. Different amines (i.e., hexylamine, decylamine, octadecylamine, cyclohexylamine, dicyclohexylamine, and quinuclidine) are investigated in a model system, as well as in a practical rubber compound by taking the ones with DPG and without amine as references. The kinetics of the silanization reaction of the silica/silane mixtures are evaluated using model compounds. The mixtures with amines show up to 3.7 times higher rate constants of the primary silanization reaction compared to the compound without amine. Linear aliphatic amines promote the rate constant of the primary silanization reaction to a greater extent compared to amines with a cyclic structure. The amines with short-alkyl chains that provide better accessibility towards the silica surface, enhance the primary silanization reaction more than the ones with long-alkyl chains. The different amines have no significant influence on the rate constant of the secondary silanization reaction. The amine types that give a higher primary silanization reaction rate constant show a lower flocculation rate in the practical compounds. For the systems with a bit lower primary silanization reaction rate, but higher extent of shielding or physical adsorption that still promotes higher interfacial compatibility between the elastomer and the filler surface, the rubber compounds show a lower Payne effect which would indicate lower filler-filler interaction. However, the flocculation rate constant remained high.

7.
Pharmacopsychiatry ; 48(3): 118-20, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25723148

RESUMO

Yawning often occurs during states of increased sleep propensity. Depression is associated with sleep problems and tiredness. The aim of this paper is to review the present knowledge about possible changes of yawning during an episode of major depression (MD) and to report data on yawning from an online depression forum comprising of 450,000 postings. A literature search did not reveal any study about yawning in people with MD when compared to controls. However, there is evidence for an increased frequency of yawning under the influence of antidepressants. Analysis of the depression forum postings revealed 63 people writing about increased yawning in the context of depression. However, all but one of them were treated with antidepressants; and yawning was not reported as a symptom of depression, but in most cases (N=56) as occurring as a result of treatment with antidepressants. These findings are in agreement with a tonic hyperarousal in typical depression which is reduced by all standard antidepressants. For clinicians, it would be of interest to know whether yawning is reduced in untreated depression and whether it predicts treatment outcome.


Assuntos
Depressão/fisiopatologia , Bocejo/fisiologia , Depressão/diagnóstico , Humanos
9.
Int J STD AIDS ; 23(2): 115-9, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22422686

RESUMO

To investigate the relationship between alcohol consumption and the experience of sexual assault, either as victim or perpetrator, among genitourinary (GU) medicine department attendees in Portsmouth, UK, we carried out a cross-sectional survey of consecutive patients attending the walk-in service when a researcher was available. Self-completed questionnaires were used and anonymized data were collected from 1186 participants (response rate 34%). Responses showed that 15.6% of female and 3.7% of male participants had ever being sexually assaulted. Women who reported sexual assault drank more on a heavy night out than those who did not report sexual assault (mean 21.3 versus 17.0 units, P = 0.041). Over half of the victims had been drinking prior to the relevant assault. Twenty-seven participants (2.3%) admitted to having sex with a person who was not fully willing. Of these, 59% had been drinking prior to the assault, and the majority believed alcohol had contributed to the assault. Any strategies aiming to reduce the incidence of sexual assault must address hazardous drinking as a high priority.


Assuntos
Consumo de Bebidas Alcoólicas/epidemiologia , Delitos Sexuais/estatística & dados numéricos , Estudos Transversais , Inglaterra/epidemiologia , Feminino , Departamentos Hospitalares/estatística & dados numéricos , Humanos , Incidência , Masculino , Inquéritos e Questionários
10.
Int J STD AIDS ; 22(9): 512-3, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21890547

RESUMO

A small cluster of infectious syphilis among young heterosexuals aged under 25 years in south-east Hampshire has highlighted the limitations of effective partner notification, the challenges of providing effective awareness raising and the need for increased accessibility to genitourinary (GU) medicine services. Evaluation of awareness raising to both the target age group and health care professionals indicated that the strategies employed did not increase testing and had limited impact on young people in terms of seeking further information.


Assuntos
Busca de Comunicante/estatística & dados numéricos , Conhecimentos, Atitudes e Prática em Saúde , Acessibilidade aos Serviços de Saúde , Heterossexualidade/estatística & dados numéricos , Sífilis/epidemiologia , Adolescente , Adulto , Análise por Conglomerados , Meios de Comunicação , Inglaterra/epidemiologia , Feminino , Pessoal de Saúde/psicologia , Promoção da Saúde , Humanos , Masculino , Sífilis/diagnóstico , Sífilis/prevenção & controle , Adulto Jovem
11.
Rev Sci Instrum ; 81(10): 105102, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21034114

RESUMO

We describe the design and performance of a pressure-jump instrument for time-resolved NMR experiments. Initial pressure of up to 250 bars can be produced by means of a HPLC pump and distilled water as a pressure-transmitting liquid. Fast pressure release at a time resolution of 3 ms is achieved using a fast acting valve driven by a piezostack close to the sample chamber. The pressure-jump cell is placed together with two valves in an especially designed NMR probe, which can be used in standard spectrometers with wide-bore magnets. All functions of the instrument are personal computer controlled. The equipment is designed for investigations on systems of biological interest, especially lipid-water dispersions. A theoretical consideration implies that probably the limited speed of valve opening determines the lower boundary of the jump time. The performance is illustrated by time-resolved NMR spectra across the phase transition of a phospholipid-water dispersion after a pressure jump from 100 bars to atmospheric pressure.


Assuntos
Espectroscopia de Ressonância Magnética/instrumentação , Pressão , Computadores , Reprodutibilidade dos Testes , Fatores de Tempo
12.
Int J STD AIDS ; 19(11): 744-6, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18931266

RESUMO

There is currently a debate as to whether microscopy is necessary in asymptomatic men presenting for a sexual health screen. Arguments favouring microscopy include finding chlamydia in a significant proportion of sexual partners of men with non-specific urethritis (NSU) in studies that included symptomatic men. We aimed to investigate the proportion of partners of men with asymptomatic NSU who were diagnosed with a sexually transmitted infection. A retrospective case-note review was carried out for all men diagnosed with asymptomatic pathogen-negative NSU, and their traced sexual contacts, during a nine-month period. As a result of contact-tracing, we identified 42 partners who attended the clinic. Only one partner (2.4%) tested positive for chlamydia. A further two partners were diagnosed with a viral sexually transmitted infection (STI). The low level of chlamydia and other STIs in partners of asymptomatic men with pathogen-negative NSU does not support the routine use of microscopy to identify these patients.


Assuntos
Infecções por Chlamydia/epidemiologia , Chlamydia trachomatis/isolamento & purificação , Infecções Sexualmente Transmissíveis/microbiologia , Uretrite/microbiologia , Cervicite Uterina/epidemiologia , Adolescente , Adulto , Infecções por Chlamydia/diagnóstico , Busca de Comunicante , Feminino , Humanos , Masculino , Saúde do Homem , Pessoa de Meia-Idade , Neutrófilos/microbiologia , Neutrófilos/patologia , Estudos Retrospectivos , Parceiros Sexuais , Infecções Sexualmente Transmissíveis/diagnóstico , Reino Unido/epidemiologia , Uretrite/diagnóstico , Cervicite Uterina/diagnóstico , Cervicite Uterina/microbiologia , Adulto Jovem
13.
Clin Hemorheol Microcirc ; 39(1-4): 99-111, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18503116

RESUMO

INTRODUCTION: The study's objective was to determine the effects of the administration of N-acetylcysteine (NAC) and of tirilazad mesylate (TM) on intestinal functional capillary density, mesenteric plasma extravasation, leukocyte adherence and on cytokine release during experimental endotoxemia in rats. METHODS: In a prospective, randomized, controlled animal study, 80 male Wistar rats were examined in 2 test series. Both series were divided into 4 groups. Group 1 served as control group (CON group). Group 2 (LPS group), group 3 (NAC group) and group 4 (TM group) received endotoxin infusions (10 mg/kg over 2 h). In NAC group 150 mg/kg body weight NAC was administered after the first 30 minutes of endotoxemia intravenously. In TM group, 10 mg/kg body weight TM was administered after the first 30 minutes of endotoxemia intravenously. Animals of the series 1 underwent studies of leukocyte adherence on submucosal venular endothelium of the small bowel wall and intestinal functional capillary density (FCD) in the intestinal mucosa and the circular as well as the longitudinal muscle layer by intravital fluorescence microscopy (IVM). Plasma levels of interleukin 1beta (IL-1beta), interferone gamma (IFN-gamma) and soluble intercellular adhesion molecule1 (s-ICAM 1) as well as white blood cell count (WBC) were estimated. In the animals of the series 2 mesenteric plasma extravasation was determined by IVM and plasma levels of tumor necrosis factor alpha (TNF-alpha), IL-4, IL-6, IL-10 and malondialdehyde (MDA) were estimated. RESULTS: After LPS administration, FCD in the villi intestinales was unchanged and in the longitudinal muscularis layer it was increased. There was no effect of NAC or TM administration on FCD.Although the plasma extravasation was not significantly influenced by LPS administration, TM administration resulted in a lower plasma extravasation in the TM group compared to the other groups. After endotoxin challenge, the firmly adherence of leukocytes to vascular endothelium as a parameter of leukocyte activation in endotoxemia was increased but NAC or TM administration had no influence on leukocyte adherence. The plasma levels of IL-1beta, IL-6, IL-10, TNF-alpha, IFN-gamma and sICAM-1 were increased in the endotoxemic groups (LPS group, NAC group and TM group) and the WBC was decreased compared to controls. IL-4 levels were unchanged during observation period. Plasma MDA levels were not influenced by LPS administration compared to controls. The administration of NAC resulted in lower sICAM-1 and MDA levels compared to the LPS group. The IL-1beta, IL-6, IL-10, TNF-alpha and IFN-gamma plasma levels were not influenced by NAC or TM administration. CONCLUSIONS: In this posttreatment sepsis model in rats, NAC administration resulted in lower sICAM-1 and MDA levels compared to the LPS treated animals. TM administration reduced the plasma extravasation in this model.


Assuntos
Acetilcisteína/farmacologia , Capilares/efeitos dos fármacos , Citocinas/metabolismo , Endotoxemia/sangue , Intestinos/irrigação sanguínea , Leucócitos/citologia , Pregnatrienos/farmacologia , Animais , Antioxidantes/farmacologia , Capilares/metabolismo , Adesão Celular , Endotoxinas/metabolismo , Frequência Cardíaca , Leucócitos/efeitos dos fármacos , Leucócitos/metabolismo , Masculino , Ratos , Ratos Wistar
14.
Artigo em Alemão | MEDLINE | ID: mdl-18385961

RESUMO

Optimised treatment of depression is important to patients and their families and has important health economic implications in Germany. The optimised treatment of depression can best be achieved with multilevel interventions targeting different groups. The "German Alliance Against Depression" emerged within the framework of the "German Research Network on Depression and Suicidality". This action-oriented programme aims to improve the care of depressed patients through parallel interventions on four levels. These levels are as follows: 1) co-operation with general practitioners, 2) a public relations campaign, 3) training programmes for community facilitators and 4) interventions with high-risk groups. The programme was tested in Nuremberg. Results were promising with a 24% decrease in suicidal behaviour reported. In the meantime, groups in Germany and abroad declared their interest in adapting the programme. Today, close to 40 German regions have implemented similar multilevel interventions. The European Alliance Against Depression (EAAD) formed and now includes 17 countries. The EAAD was mentioned in the 2005 EU green paper on mental health as an "example for best practice". Improving the care of affected persons requires a systematic research approach. The "Mental Health Research Network" contributes to research related to the optimisation of services for persons with mental disorders.


Assuntos
Depressão/terapia , Prevenção do Suicídio , Pesquisa Biomédica , Depressão/psicologia , Europa (Continente) , Medicina de Família e Comunidade , Alemanha , Humanos , Relações Públicas , Fatores de Risco , Suicídio/psicologia , Organização Mundial da Saúde
15.
Biophys J ; 93(9): 3132-41, 2007 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-17660321

RESUMO

Islet amyloid polypeptide (IAPP) is a pancreatic hormone and one of a number of proteins that are involved in the formation of amyloid deposits in the islets of Langerhans of type II diabetes mellitus patients. Though IAPP-membrane interactions are known to play a major role in the fibrillation process, the mechanism and the peptide's conformational changes involved are still largely unknown. To obtain new insights into the conformational dynamics of IAPP upon its aggregation at membrane interfaces and to relate these structures to its fibril formation, we studied the association of IAPP at various interfaces including neutral as well as charged phospholipids using infrared reflection absorption spectroscopy. The results obtained reveal that the interaction of human IAPP with the lipid interface is driven by the N-terminal part of the peptide and is largely driven by electrostatic interactions, as the protein is able to associate strongly with negatively charged lipids only. A two-step process is observed upon peptide binding, involving a conformational transition from a largely alpha-helical to a beta-sheet conformation, finally forming ordered fibrillar structures. As revealed by simulations of the infrared reflection absorption spectra and complementary atomic force microscopy studies, the fibrillar structures formed consist of parallel intermolecular beta-sheets lying parallel to the lipid interface but still contain a significant number of turn structures. We may assume that these dynamical conformational changes observed for negatively charged lipid interfaces play an important role as the first steps of IAPP-induced membrane damage in type II diabetes.


Assuntos
Amiloide/química , Amiloide/metabolismo , Fosfatidilcolinas/metabolismo , Fosfatidilgliceróis/metabolismo , Adsorção , Amiloide/farmacocinética , Animais , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Fosfatidilcolinas/química , Fosfatidilgliceróis/química , Ratos , Espectrofotometria Infravermelho , Eletricidade Estática , Água/metabolismo
16.
J Trauma Stress ; 20(3): 239-49, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17597132

RESUMO

The present study evaluated whether Posttraumatic Stress Disorder (PTSD) symptom severity was associated with participation and treatment outcomes comparing a Vipassana meditation course to treatment as usual in an incarcerated sample. This study utilizes secondary data. The original study demonstrated that Vipassana meditation is associated with reductions in substance use. The present study found that PTSD symptom severity did not differ significantly between those who did and did not volunteer to take the course. Participation in the Vipassana course was associated with significantly greater reductions in substance use than treatment as usual, regardless of PTSD symptom severity levels. These results suggest that Vipassana meditation is worthy of further study for those with comorbid PTSD and substance use problems.


Assuntos
Alcoolismo/reabilitação , Meditação , Prisioneiros/psicologia , Transtornos de Estresse Pós-Traumáticos/reabilitação , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Adulto , Alcoolismo/diagnóstico , Alcoolismo/psicologia , Comorbidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Centros de Reabilitação , Transtornos de Estresse Pós-Traumáticos/diagnóstico , Transtornos de Estresse Pós-Traumáticos/psicologia , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Transtornos Relacionados ao Uso de Substâncias/psicologia
17.
Eur Biophys J ; 36(4-5): 425-35, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16909276

RESUMO

The interaction between the negatively charged phospholipid DPPG and positively charged poly(L: -lysine) (PLL) of different lengths was studied by X-ray scattering in the SAXS and WAXS region. As a reference pure DPPG (Na salt) was investigated over a wide temperature range (-30 to 70 degrees C). The phase behavior of DPPG in aqueous and in buffer/salt dispersions showed a metastable subgel phase at low temperatures and a recrystallization upon heating before reaching the liquid-crystalline phase. The presence of additional salt stabilizes the bilayer structure and decreases the recrystallization temperature. Large changes in the SAXS region are not connected with changes in chain packing. In DPPG/PLL samples, the PLL is inserted between adjacent headgroup layers and liberates counterions which give rise to a freezing point depression. In the complex with DPPG PLL form an alpha-helical secondary structure at pH 7 and temperatures below the gel to liquid-crystalline phase transition. This prevents DPPG from recrystallization and strongly increases the stacking order. The lamellar repeat distance is decreased and fixed by the helix conformation of PLL in the gel phase. PLL with n = 14 is too short to form helices and is squeezed out reversibly from the interbilayer space upon cooling by freezing of trapped water. In dispersions with longer PLLs (n > 400) at -20 degrees C a 1D crystallization of PLL alpha-helices in the aqueous layer between the headgroups takes place. A structural model is presented for the lateral periodic complex, which is similar to the known cationic lipid/DNA complex.


Assuntos
Coloides/química , Bicamadas Lipídicas/química , Lipossomos/química , Modelos Químicos , Fosfatidilgliceróis/química , Polilisina/química , Água/química , Simulação por Computador , Modelos Moleculares , Conformação Molecular , Soluções , Difração de Raios X/métodos
18.
Int J Artif Organs ; 28(1): 66-73, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15742312

RESUMO

Fourier transform infrared microscopy was used to investigate human cortical bone samples before and after treatment with increasing doses of X-ray radiation. Especially the spectral region of the v1 and v3 phosphate vibrations of hydroxyapatite, the main mineral component of bone, and the region of the amide I and amide II vibrational bands due to the collagen extracellular matrix were examined. Major spectral changes in the phosphate region between 1250-1000 cm(-1) occur after irradiation doses between 1 and 4 Gray. These findings are explained by a decrease in size of mineral crystallites and by variances of the toichiometric/non-stoichiometric apatite composition. The Ca2+ /PO4(3-) /HPO4(2-) composition in the biological apatite is altered near the bone surface. The secondary structure of the collagen matrix is not affected by cumulative irradiation up to doses of 15 Gray as indicated by the unchanged frequency maximum and contour shape of the amide I band between 1600-1700 cm(-1) . However, side chain carboxylate groups of the collagen matrix that are involved in coordination with apatite bound calcium ions are partially removed by decarboxylation upon irradiation. Concomitantly, a loss of acidic phosphate groups due to a formation of phosphate groups with bound calcium is observed. These changes on a molecular level can be correlated with alterations in the mechanical properties of the bone samples, e.g. with an increased embrittlement as deduced from experiments with a scanning acoustic microscope.


Assuntos
Osso e Ossos/efeitos da radiação , Amidas/química , Amidas/efeitos da radiação , Osso e Ossos/química , Cálcio/química , Cálcio/efeitos da radiação , Ácidos Carboxílicos/química , Ácidos Carboxílicos/efeitos da radiação , Colágeno/química , Colágeno/efeitos da radiação , Cristalografia , Durapatita/química , Durapatita/efeitos da radiação , Humanos , Microespectrofotometria , Fosfatos/química , Fosfatos/efeitos da radiação , Doses de Radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Raios X
19.
J Hum Hypertens ; 16 Suppl 3: S64-70, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12140731

RESUMO

Biochemical, physiological and functional studies suggest that the brain renin-angiotensin system (RAS) is regulated independently of the peripheral RAS. The classical actions of angiotensin II in the brain include blood pressure control, drinking behaviour, natriuresis and the release of vasopressin into the circulation. At least two subtypes of G-protein coupled receptors, the AT(1) and the AT(2) receptor, have been identified. Most of the classic actions of angiotensin II in the brain are mediated by AT(1) receptors. The AT(2) receptor is involved in brain development and neuronal regeneration and protection. Additionally, AT(2) receptors can modulate some of the classic angiotensin II actions in the brain. Selective non-peptide AT(1) receptor blockers, applied systemically, have been shown to inhibit both peripheral and brain AT(1)receptors. In genetically hypertensive rats, inhibition of brain AT(1) receptors may contribute to the blood pressure lowering effects of AT(1) receptor blockers. Animal studies have shown that AT(1) receptor antagonists enable endogenous angiotensin II to stimulate neuronal regeneration via activation of AT(2) receptors. In animal models, inhibition of the brain RAS proved to be beneficial with respect to stroke incidence and outcome. Blockade of brain and cerebrovascular AT(1) receptors by AT(1) receptor blockers prevents the reduction in blood flow during brain ischaemia, reduces the volume of ischaemic injury and improves neurological outcome after brain ischaemia. This paper reviews the actions of angiotensin II and its receptors in the brain, and discusses the possible consequences of AT(1) receptor blockade in neuroprotection, neuroregeneration, cerebral haemodynamics and ischaemia.


Assuntos
Antagonistas de Receptores de Angiotensina , Encéfalo/metabolismo , Sistema Renina-Angiotensina/fisiologia , Animais , Isquemia Encefálica/tratamento farmacológico , Isquemia Encefálica/fisiopatologia , Circulação Cerebrovascular/efeitos dos fármacos , Receptor Tipo 1 de Angiotensina
20.
Neuropharmacology ; 42(2): 281-8, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11804625

RESUMO

Angiotensin II (Ang II) acts as a neuromodulator/neurotransmitter in specific brain nuclei involved in the regulation of blood pressure and volume homeostasis. It also induces a highly differentiated transcription factor expression in these nuclei. We investigated whether adrenoceptors, which modulate other central actions of angiotensin II like the vasopressin release, also play a role in the AT1 receptor-mediated expression of the transcription factors (TF) c-Fos, c-Jun and Krox-24 in the rat brain. Ang II, injected intracerebroventricularly, induced the expression of c-Fos, c-Jun and Krox-24 in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Pretreatment with the alpha 1-adrenoceptor antagonist, prazosin, significantly inhibited the Ang II-induced transcription factor expression in the SON and PVN. The alpha 2-adrenoceptor antagonist, yohimbine, also reduced Ang II-stimulated transcription factors significantly in both nuclei. This inhibition was mainly localized in vasopressinergic magnocellular neurons in both nuclei. The beta-adrenoceptor antagonist, propranolol, did not influence the Ang II-induced expression of TF. Our results show that both, Ang II-induced vasopressin release and transcription factor expression, involve the same neuronal connections in the brain, implicating that the signal transduction pathways leading to the two different effects are at least to a certain degree convergent.


Assuntos
Angiotensina II/farmacologia , Hipotálamo/metabolismo , Proteínas Imediatamente Precoces , Prosencéfalo/metabolismo , Receptores Adrenérgicos/efeitos dos fármacos , Fatores de Transcrição/biossíntese , Animais , Proteínas de Ligação a DNA/genética , Proteína 1 de Resposta de Crescimento Precoce , Genes fos/efeitos dos fármacos , Genes fos/genética , Genes jun/efeitos dos fármacos , Genes jun/genética , Hipotálamo/efeitos dos fármacos , Imuno-Histoquímica , Injeções Intraventriculares , Prosencéfalo/efeitos dos fármacos , Ratos , Ratos Wistar , Fatores de Transcrição/genética
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