RESUMO
Sexual well-being frequently declines following the menopause transition and can be associated with significant personal and relationship distress. This distress is the hallmark of female sexual dysfunction (FSD). FSD is highly prevalent in postmenopausal women. The prevalence of sexual problems increases with age, but conversely this is associated with decreasing distress with advancing age. This pattern has been seen across multiple international populations with varied cultural norms. While the etiology of FSD is multifactorial, the physiological changes of sex hormone insufficiency and postmenopausal symptoms, such as dyspareunia, are primary factors contributing to FSD at midlife. The International Menopause Society is working to increase awareness of FSD and to provide a framework for practitioners to address sexual medicine concerns. This White Paper aims to review the process of care for female sexual well-being following menopause, from initially approaching the discussion of FSD, to identifying clinical signs and symptoms, and ultimately determining the best available biopsychosocial therapies. As with most processes of care, the first step is often the most difficult. Health-care practitioners need to broach the topic of sexuality in the clinical setting. Lack of information on, comfort with, and biases about the topic of sexuality after menopause are significant hurdles that the International Menopause Society addresses in this document. Each member of the Writing Group remains committed to continued advocacy for the validity of FSD as a diagnosis, the need for therapies for women to be both available and included in health insurance coverage, and continued therapeutic research to provide evidence-based solutions.
Assuntos
Menopausa , Comportamento Sexual/psicologia , Disfunções Sexuais Fisiológicas/terapia , Disfunções Sexuais Psicogênicas/terapia , Feminino , Humanos , Qualidade de Vida , Disfunções Sexuais Fisiológicas/etiologia , Disfunções Sexuais Psicogênicas/etiologia , Sociedades MédicasRESUMO
El bienestar sexual frecuentemente disminuye después de la transición de la menopausia y puede asociarse con estrés personal y de la relación. Este estrés es la característica típica de la disfunción sexual femenina (DSF). La DSF es altamente prevalente en mujeres posmenopáusicas. La prevalencia de problemas sexuales aumenta con la edad, pero por otra parte, esto se asocia con una disminución del estrés con el avance de la edad. Este patrón se ha visto en múltiples poblaciones internacionales con variadas normas culturales. Si bien la etiología de la DSF es multifactorial, los cambios fisiológicos de la insuficiencia de las hormonas sexuales y los síntomas posmenopáusicos, como la dispareunia, son los principales factores que contribuyen a la DSF en la mediana edad. La Sociedad Internacional de Menopausia está trabajando para incrementar el conocimiento de la DSF y proporcionar un esquema para que los profesionales aborden las preocupaciones sobre medicina sexual. El presente documento técnico tiene como objetivo revisar el proceso de cuidado del bienestar sexual femenino después de la menopausia, desde un abordaje inicial de la discusión de DSF hasta identificar signos y síntomas clínicos y, en última instancia, determinar las mejores terapias biopsicosociales disponibles. Al igual que con la mayoría de los procesos de atención, el primer paso es a menudo el más difícil. Los profesionales de la salud necesitan abordar el tema de la sexualidad en el entorno clínico. La falta de información, comodidad al respecto, y los prejuicios sobre el tema de la sexualidad después de la menopausia son obstáculos importantes que la Sociedad Internacional de Menopausia aborda en este documento; cada miembro del grupo que lo escribe sigue comprometido con la defensa continua para la validación de la DSF como un diagnóstico, la necesidad de que las terapias para mujeres estén disponibles e incluidas en la cobertura del seguro de salud, y la investigación terapéutica continua para proporcionar soluciones basadas en la evidencia.
Assuntos
Pessoa de Meia-Idade , Menopausa , SexualidadeRESUMO
Thermally sensitive fluorescent indicators have been proposed to monitor temperature changes in microfluidic systems, mainly based on fluorescence intensity or lifetime. However, measuring temperature in a structured environment, such as biological tissue, presents additional challenges due to the chemical and structural complexity. Here, we investigate the potential for resolving temperature distributions within the volume of a single cell. Rhodamine B (RhB) dye was employed as a temperature indicator to compare fluorescence intensity- and lifetime-based techniques. The relationship between the fluorescence lifetime and temperature was found to be highly dependent on the biological environment. The intensity-based method allowed the temperature distribution to be mapped with partial success within the volume of a single cell. Under ideal circumstances, the temperature can be mapped pixel by pixel with a resolution better than ±0.3°C within the cell cytoplasm, but this accuracy was reduced to ±1.8°C by environmental variations. These results suggest that the fluorophore should be encapsulated and immobilized in the biological tissue in order to reduce the influence of environmental factors on temperature measurements at the cellular level.
Assuntos
Fenômenos Fisiológicos Celulares , Técnicas Citológicas/métodos , Corantes Fluorescentes/metabolismo , Fluorometria/métodos , Coloração e Rotulagem/métodos , Fenômenos Químicos , Fluorescência , Processamento de Imagem Assistida por Computador/métodos , TemperaturaRESUMO
Hypoactive Sexual Desire Disorder (HSDD) is defined as a persistent or recurrent deficiency of sexual fantasies and desire for sexual activity, which causes marked personal distress or interpersonal difficulty, and is not better accounted for by another psychiatric disorder or the direct physiological effects of a substance (e.g., a medication) or medical condition. HSDD is believed to be the most common form of Female Sexual Dysfunction and is associated with emotional distress and relationship problems. No pharmacologic therapy is approved for the treatment of HSDD in premenopausal or naturally postmenopausal women. Flibanserin is a 5-HT(1A) agonist/5-HT(2A) antagonist that is under investigation as a treatment for HSDD in women. The aim of this article is to present an overview of the pharmacology, clinical efficacy and safety of flibanserin. Flibanserin is an investigational drug that is not licensed for any indication in any country.
Assuntos
Benzimidazóis/uso terapêutico , Pré-Menopausa , Serotoninérgicos/uso terapêutico , Disfunções Sexuais Psicogênicas/tratamento farmacológico , Benzimidazóis/administração & dosagem , Benzimidazóis/efeitos adversos , Ensaios Clínicos como Assunto , Feminino , Humanos , Libido/efeitos dos fármacos , Serotoninérgicos/administração & dosagem , Serotoninérgicos/efeitos adversosRESUMO
The graphical representation of single-frequency phase-modulation fluorescence lifetime imaging data, referred to as the AB plot, is extended to take into account measurements of the polarized components of the fluorescence. For a hindered rotator model (characterized with a single excited-state lifetime, a single rotational correlation time and limiting initial and final anisotropies) the rotational correlation time and the excited lifetime can be determined from the AB plot of any two of the following emission components: parallel, perpendicular, total emission or combinations thereof. A strategy for resolving the component hindered rotations and lifetimes for mixtures of two hindered rotators from measurements of the total, parallel and perpendicular components of the emission is developed. The analysis does not require prior knowledge of the initial limiting anisotropy or of the steady-state anisotropy or of the excited state lifetime. Plots in polarized AB space derived for heterogeneous systems are constructed to aid interpretation of frequency-domain dynamic depolarization imaging microscopy experiments. These plots can be used to distinguish spatially dependent rotational correlation time heterogeneity from heterogeneity in limiting anisotropies. The effects of noise and aperture depolarization are discussed. It is anticipated that the polarized AB plot will provide a useful adjunct to existing methods for visualizing and analysing dynamic polarization phenomena arising from molecular dynamics and homo-energy transfer in single-frequency microscopy applications.
RESUMO
The adenomatous polyposis coli (APC) tumour suppressor is a multifunctional protein involved in the regulation of Wnt signalling and cytoskeletal dynamics. Little is known about how APC controls these disparate functions. In this study, we have used APC- and axin-fluorescent fusion proteins to examine the interactions between these proteins and show that the functionally distinct populations of APC are also spatially separate. Axin-RFP forms cytoplasmic punctate structures, similar to endogenous axin puncta. Axin-RFP recruits beta-catenin destruction complex proteins, including APC, beta-catenin, glycogen synthase kinase-3-beta (GSK3-beta) and casein kinase-1-alpha (CK1-alpha). Recruitment into axin-RFP puncta sequesters APC from clusters at cell extensions and this prevents its microtubule-associated functions. The interaction between APC-GFP and axin-RFP within the cytoplasmic puncta is direct and dramatically alters the dynamic properties of APC-GFP. However, recruitment of APC to axin puncta is not absolutely required for beta-catenin degradation. Instead, formation of axin puncta, mediated by the DIX domain, is required for beta-catenin degradation. An axinDeltaDIX mutant did not form puncta, but still mediated recruitment of destruction complex proteins and phosphorylation of beta-catenin. We conclude that there are distinct pools of APC and that the formation of axin puncta, rather than the axin/APC complex, is essential for beta-catenin destruction.
Assuntos
Proteína da Polipose Adenomatosa do Colo/metabolismo , Proteínas Repressoras/metabolismo , beta Catenina/metabolismo , Proteína da Polipose Adenomatosa do Colo/genética , Animais , Proteína Axina , Linhagem Celular , Citoplasma/metabolismo , Citoplasma/ultraestrutura , Cães , Transferência Ressonante de Energia de Fluorescência , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Camundongos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Repressoras/genéticaRESUMO
Fibromyalgia is an enigmatic medical condition whose specific etiology remains undiscovered but currently plagues five million Americans. Research indicates that the origin of the disease is most likely multifactorial. Treatment should therefore be tailored accordingly. Thus, it is often necessary to combine different options in order to achieve the maximum benefit in patients suffering from fibromyalgia.
Assuntos
Fibromialgia/tratamento farmacológico , Terapia Cognitivo-Comportamental , Quimioterapia Combinada , Terapia por Exercício , Fibromialgia/etiologia , Fibromialgia/terapia , HumanosRESUMO
The binding, conformation and orientation of a hydrophilic vector peptide penetratin in lipid membranes and its state of self-association in solution were examined using circular dichroism (CD), analytical ultracentrifugation and fluorescence spectroscopy. In aqueous solution, penetratin exhibited a low helicity and sedimented as a monomer in the concentration range approximately 50-500 microM. The partitioning of penetratin into phospholipid vesicles was determined using tryptophan fluorescence anisotropy titrations. The apparent penetratin affinity for 20% phosphatidylserine/80% egg phosphatidylcholine vesicles was inversely related to the total peptide concentration implying repulsive peptide-peptide interactions on the lipid surface. The circular dichroism spectra of the peptide when bound to unaligned 20% phosphatidylserine/80% egg phosphatidylcholine vesicles and aligned hydrated phospholipid multilayers were attributed to the presence of both alpha-helical and beta-turn structures. The orientation of the secondary structural elements was determined using oriented circular dichroism spectroscopy. From the known circular dichroism tensor components of the alpha-helix, it can be concluded that the orientation of the helical structures is predominantly perpendicular to the membrane surface, while that of the beta-type carbonyls is parallel to the membrane surface. On the basis of our observations, we propose a novel model for penetratin translocation.
Assuntos
Proteínas de Transporte/química , Membranas Artificiais , Fosfolipídeos/química , Peptídeos Penetradores de Células , Conformação ProteicaRESUMO
OBJECTIVE: Gender differences in clinical presentation and response to sertraline treatment were examined for patients diagnosed with DSM-III-R panic disorder with or without agoraphobia. METHOD: Data was pooled from 4 double-blind, placebo-controlled outpatient studies (males, N = 335; females, N = 338). Two were 12-week fixed-dose studies (sertraline 50 mg vs. 100 mg vs. 200 mg) and 2 were 10-week flexible-dose studies (sertraline 50-200 mg). Primary outcome measures consisted of the Clinical Global Impression-Improvement scale (CGI-I) and change in panic attack frequency. RESULTS: The clinical presentation of panic disorder was similar except that men reported an earlier age of onset, shorter duration of illness, and significantly more frequent history of alcohol and/or substance dependence/abuse. Sertraline was significantly more effective than placebo in both women and men on the 2 primary outcome measures. When between-sex efficacy was compared, women achieved significantly greater improvement than men on panic frequency and CGI-I, but had equivalent improvement on all other measures. There was no significant between-sex difference in study completion rates, or in adverse event profiles. CONCLUSIONS: There was a modest but consistent trend for women to show superior efficacy at the end of acute sertraline treatment. This gender effect only occasionally achieved significance, and must be confirmed by future treatment research.
Assuntos
Transtorno de Pânico/tratamento farmacológico , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Sertralina/farmacologia , Adulto , Agorafobia/tratamento farmacológico , Agorafobia/psicologia , Análise de Variância , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Humanos , Masculino , Transtorno de Pânico/psicologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores Sexuais , Análise de Sobrevida , Resultado do Tratamento , Estados UnidosRESUMO
Premenstrual symptoms can pose significant problems for a large number of women; this small exploratory study was designed to investigate biological markers that may provide etiological clues. Using an algorithm based on daily symptom charting for two months, 15 participants were assigned to one of three study groups: non-symptomatic (n = 9), probable PMS (n = 3) and probable PMDD (n = 3). During two overnight admissions, one prior to and one following the onset of menses, participants had blood drawn to assess the level of available serotonin via one of its metabolites, 5-HIAA. The three groups exhibited potentially significant differences in several biological markers. This study's results are consistent with a hypothesis implicating serotonin in the generation of premenstrual symptomology.
Assuntos
Fase Luteal/sangue , Síndrome Pré-Menstrual/sangue , Serotonina/sangue , Adulto , Análise de Variância , Biomarcadores/análise , Feminino , Humanos , Saúde da MulherRESUMO
Most treatments of frequency domain lifetime measurements indicate that a set of measurements must be made at multiple frequencies in order to determine the lifetimes of the components in a mixture. Although this is the case in general, under special conditions, single-frequency data can resolve multiple lifetimes. Here, data are presented showing several approaches to determining fluorescence lifetimes in two-component mixtures using single-frequency data. Common to all of the procedures presented is exploitation of variations in the relative contributions of a particular fluorophore to the total fluorescence from a mixture of fluorophores. This variation can be produced intentionally by observing a number of samples which contain different relative amounts of the fluorophores. It can be produced fortuitously by observing spatial variations in a mixture of fluorophores in a specimen or set of specimens observed with a lifetime imaging system. It can also be produced by examination of the lifetime spectrum obtained from a fluorophore mixture or by varying the concentration of a quencher in a fluorophore mixture, in which the two fluorophores have different rate constants for quenching. In many instances, the set of approaches presented here will be unsuitable for examination of arbitrary samples of unknown composition for which the multifrequency approach should be used. However, measurements produced using single-frequency methods may be applied to good effect for controlled experiments having defined fluorophores or sets of fluorophores, particularly in the case of biological lifetime imaging studies.
RESUMO
The membrane-binding properties of a class A amphipathic peptide (18D) were investigated using two different immobilized model membrane systems. The first system involved the use of surface plasmon resonance (SPR) to study the binding of 18D to dimyristylphosphatidylcholine (DMPC) and dimyristylphosphatidylglycerol (DMPG), which allowed peptide binding to be monitored in real time. The SPR experiments indicated stronger binding of 18D to DMPG than DMPC, which kinetic analysis revealed was due to a faster on-rate. The second model membrane system involved immobilized membrane chromatography in which the binding of 18D to either DMPC or DMPG monolayers covalently linked to silica particles was analysed by elution chromatography. Stronger binding affinity of 18D was also obtained with the negatively charged phosphatidylglycerol (PG) monolayer compared to the phosphatidylcholine (PC) monolayer, which was consistent with the SPR results. Non-linear binding behaviour of 18D to the immobilized lipid monolayers was also observed, which suggests that the peptide undergoes conformational and orientational changes upon binding to the immobilized PC and PG ligands. Significant band broadening was also observed on both monolayers, with larger bandwidths obtained on the PC surface, indicating slower binding and orientation kinetics with the zwitterionic surface. The dependence of logk' on the percentage of methanol also demonstrated a bimodal interaction whereby hydrophobic forces predominated at higher temperatures and methanol concentrations, while at lower temperatures, electrostatic and other polar forces also made a contribution to the affinity of the peptides for the lipid monolayer particularly. Overall, these results demonstrate the complementary use of these two lipid biosensors which allows the role of hydrophobic and electrostatic forces in peptide-membrane interactions to be studied and insight gained into the kinetic factors associated with these interactions.
Assuntos
Técnicas Biossensoriais/métodos , Dimiristoilfosfatidilcolina/química , Bicamadas Lipídicas/química , Lipossomos/química , Proteínas de Membrana/química , Peptídeos/química , Fosfatidilgliceróis/química , Sítios de Ligação , Cromatografia/métodos , Fluidez de Membrana , Membranas Artificiais , Ligação Proteica , Ressonância de Plasmônio de Superfície/métodos , TemperaturaRESUMO
Graphical representation of fluorescence lifetime imaging microscopy data demonstrates that a mixture of two components with single exponential decays can be resolved by single frequency measurements. We derive a method based on linear fitting that allows the calculation of the fluorescence lifetimes of the two components. We show that introduction of proper error-weighting results in a non-linear method that is mathematically identical to a global analysis algorithm that was recently derived. The graphical approach was applied to cellular data obtained from a lifetime-based phosphorylation assay for the epidermal growth factor receptor and yielded results similar to those obtained by a global analysis algorithm.
Assuntos
Carbocianinas/metabolismo , Receptores ErbB/metabolismo , Corantes Fluorescentes/metabolismo , Processamento de Imagem Assistida por Computador/métodos , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência/métodos , Linhagem Celular , Transferência Ressonante de Energia de Fluorescência , Proteínas de Fluorescência Verde , Humanos , Fosforilação , Fosfotirosina/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Células Tumorais CultivadasRESUMO
We report the implementation and exploitation of fluorescence polarization measurements, in the form of anisotropy fluorescence lifetime imaging microscopy (rFLIM) and energy migration Förster resonance energy transfer (emFRET) modalities, for wide-field, confocal laser-scanning microscopy and flow cytometry of cells. These methods permit the assessment of rotational motion, association and proximity of cellular proteins in vivo. They are particularly applicable to probes generated by fusions of visible fluorescence proteins, as exemplified by studies of the erbB receptor tyrosine kinases involved in growth-factor-mediated signal transduction.
Assuntos
Anisotropia , Microscopia de Fluorescência/instrumentação , Microscopia de Fluorescência/métodos , Animais , Células CHO , Linhagem Celular , Cricetinae , Relação Dose-Resposta a Droga , Receptores ErbB/química , Citometria de Fluxo , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/metabolismo , Microscopia Confocal , Modelos Estatísticos , MutaçãoRESUMO
BACKGROUND: We examine changes in sexual functioning and depressive symptoms in patients' transition from a selective serotonin reuptake inhibitor (SSRI), which induced both a therapeutic response and sexual dysfunction, to bupropion sustained release (SR) over the course of an 8-week trial. METHOD: The study included 11 adults (8 women and 3 men) who had a DSM-IV diagnosis of major depressive disorder in remission (Hamilton Rating Scale for Depression [HAM-D] score < 11) and were receiving an SSRI. Depression (using the HAM-D) and sexual dysfunction (using the Changes in Sexual Functioning Questionnaire) were assessed at baseline, 2 weeks after bupropion SR was added to the current antidepressant (combined treatment), 2 weeks after taper of the SSRI was initiated and completed, and after 4 weeks of bupropion SR monotherapy. T tests were performed to assess changes in depression and sexual function. RESULTS: Patient participation dropped from the initial group of 11 at week 2 to 9 at week 4 and to 6 by week 8. Sexual functioning improved from week 0 (baseline) to week 2 and from week 2 to week 4. The patients showed no significant change in mean HAM-D scores in weekly comparisons during the study period; 55% of patients completed the substitution without significant adverse events or recurrence of depressive symptoms. CONCLUSION: Bupropion SR as a treatment for depression also alleviates sexual dysfunction due to SSRI treatment. Results show that sexual functioning improves after the addition of bupropion SR to SSRI treatment and continues to improve, after discontinuation of the SSRI, with bupropion SR treatment alone.
Assuntos
Antidepressivos de Segunda Geração/uso terapêutico , Bupropiona , Bupropiona/uso terapêutico , Transtorno Depressivo/tratamento farmacológico , Inibidores Seletivos de Recaptação de Serotonina/efeitos adversos , Disfunções Sexuais Psicogênicas/induzido quimicamente , Disfunções Sexuais Psicogênicas/tratamento farmacológico , Adulto , Antidepressivos de Segunda Geração/administração & dosagem , Bupropiona/administração & dosagem , Cicloexanóis/efeitos adversos , Cicloexanóis/uso terapêutico , Preparações de Ação Retardada , Transtorno Depressivo/psicologia , Esquema de Medicação , Quimioterapia Combinada , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inibidores Seletivos de Recaptação de Serotonina/uso terapêutico , Comportamento Sexual/efeitos dos fármacos , Disfunções Sexuais Psicogênicas/prevenção & controle , Inquéritos e Questionários , Resultado do Tratamento , Cloridrato de VenlafaxinaRESUMO
To aid the development of custom peptide antibiotics, a kinetic study of membrane lysis by cecropin B (CB) and its analogs, cecropin B1 (CB1) and cecropin B3 (CB3) was carried out to determine the mechanism by which these peptides disrupt the bilayer structure of liposomes of defined composition. Disruption of the phospholipid bilayer was determined by a fluorescence assay involving the use of dithionite to quench the fluorescence of lipids labeled with N-7-nitro-2,1,3-benzoxadiazol-4-yl. Lytic peptides caused the disruption of liposomes to occur in two kinetic steps. For liposomes composed of mixtures of phosphatidylcholine and phosphatidic acid, the time constants for each kinetic step were shorter for CB and CB1 than for CB3. Oriented circular dichroism experiments showed that the peptides could exist in at least two different membrane-associated states that differed primarily in the orientation of the helical segments with respect to the bilayer surface. The results are discussed in terms of kinetic mechanisms of membrane lysis. The mode of actions of these peptides used for the interpretation of their kinetic mechanisms were supported by surface plasmon resonance experiments including or excluding the pore-forming activities.
Assuntos
Proteínas de Insetos/metabolismo , Sequência de Aminoácidos , Membrana Celular/metabolismo , Dicroísmo Circular , Proteínas de Insetos/química , Cinética , Lipossomos , Dados de Sequência Molecular , Espectrometria de FluorescênciaRESUMO
Recognition of sexual dysfunction associated with depression or its treatment is critical for patient satisfaction and medication compliance. This report reviews relevant literature related to types of sexual problems, the etiology of sexual dysfunction, prevalence rates, barriers to assessment, and available instruments for evaluating sexual functioning in individuals with depression. Evaluation of sexual functioning should include examination of each phase of the sexual response cycle, with classification of sexual disorders as described in the DSM-IV. Sexual functioning requires both an adequate hormonal milieu and appropriate neurotransmitter functioning. Evaluation of sexual functioning should include a sexual history, current level of sexual functioning, history and current diagnoses of medical and psychiatric illnesses, evaluation of medications and/or other substances taken, indicated endocrine measures, and targeted physical examination. Appropriate evaluation of sexual functioning associated with depression could help reduce the enormous societal costs of this disorder.
Assuntos
Transtorno Depressivo/diagnóstico , Disfunções Sexuais Psicogênicas/diagnóstico , Antidepressivos/efeitos adversos , Antidepressivos/farmacologia , Transtorno Depressivo/complicações , Transtorno Depressivo/psicologia , Feminino , Humanos , Masculino , Anamnese , Inventário de Personalidade , Exame Físico , Prevalência , Escalas de Graduação Psiquiátrica , Psicometria , Comportamento Sexual/efeitos dos fármacos , Comportamento Sexual/fisiologia , Comportamento Sexual/psicologia , Disfunções Sexuais Psicogênicas/epidemiologia , Disfunções Sexuais Psicogênicas/psicologia , Inquéritos e Questionários , Estados Unidos/epidemiologiaRESUMO
The effect of lipid phase state on the orientation and conformation of a class A alpha-helical peptide on aligned lipid multilayers was examined using oriented circular dichroism spectroscopy. A comparison of oriented spectra in aligned peptide-lipid multilayers with CD spectra of unaligned peptide lipid vesicle complexes is consistent with a preferential alignment of helices parallel to the membrane surface at temperatures above and below the main acyl-chain melting transition temperature of the phospholipid. Changes are observed in the oriented CD spectra with lipid phase state which are attributed to a subtle conformational change of the peptide on the lipid surface. The results are compared with available experimental data on membrane-active lytic and antimicrobial helical peptides.
Assuntos
Membranas Artificiais , Peptídeos/química , Fosfolipídeos/química , Sequência de Aminoácidos , Dicroísmo Circular , Dimiristoilfosfatidilcolina/química , Dados de Sequência Molecular , Estrutura Secundária de Proteína , TemperaturaRESUMO
The amphipathic helix plays a key role in many membrane-associating peptides and proteins. The dynamics of helices on membrane surfaces might be of importance to their function. The fluorescence anisotropy decay of tryptophan is a sensitive indicator of local, segmental, and global dynamics within a peptide or protein. We describe the use of frequency domain dynamic depolarization measurements to determine the site-specific tryptophan dynamics of single tryptophan amphipathic peptides bound to a phospholipid surface. The five 18-residue peptides studied are based on a class A amphipathic peptide that is known to associate at the interface of phospholipid bilayers. The peptides contain a single tryptophan located at positions 2, 3, 7, 12, or 14 in the sequence. Association of the peptides with egg phosphatidylcholine vesicles results in complex behavior of both the tryptophan intensity decay and the anisotropy decay. The anisotropy decays were biphasic and were fitted to an associated model where each lifetime component in the intensity decay is associated with a particular rotational correlation time from the anisotropy decay. In contrast, an unassociated model where all components of the intensity decay share common rotational modes was unable to provide an adequate fit to the data. Two correlation times were resolved from the associated analysis: one whose contribution to the anisotropy decay was dependent on the exposure of the tryptophan to the aqueous phase, and the other whose contribution reflected the position of the tryptophan in the sequence. The results are compared with existing x-ray structural data and molecular dynamics simulations of membrane-incorporated peptides.
Assuntos
Bicamadas Lipídicas/química , Peptídeos/química , Estrutura Secundária de Proteína , Triptofano , Sequência de Aminoácidos , Polarização de Fluorescência , Modelos Moleculares , Dados de Sequência Molecular , Fosfatidilcolinas/química , Proteínas/química , Relação Estrutura-Atividade , Difração de Raios XRESUMO
In a study of 115 women who presented with complaints of premenstrual symptoms, we investigated the relationship between the menstrual cycle and different aspects of sexual functioning, using the Changes in Sexual Functioning Questionnaire. Women who were assessed at the screening visit during the late luteal phase of their menstrual cycle reported less desire to engage in sexual activity and less frequent sexual activity than women who were assessed during other phases of the menstrual cycle. The 24 women who returned for the second and third visits reported less frequent orgasms and less satisfaction from their orgasms premenstrually than during midcycle.