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1.
Brain Behav Immun ; 120: 117-118, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38788966
3.
J Psychiatr Res ; 165: 248-253, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37531843

RESUMO

Clinician-rated symptom scales are the current standard for outcome measures in Schizophrenia Spectrum Disorders (SSD) research. There has been growing interest in the development of self-report measures for people with SSD to support measurement-based care and inclusive research. We developed the Inspire Self Report Scale (ISRS), which measures the current magnitude of well-being, mood symptoms, psychosis, negative symptoms and cognition using 10 questions on a Likert or Visual analogue scale (VAS). The main aim of this report was to investigate the correlation and concordance between patient self-report and clinician ratings on the ISRS during a clinical encounter. When ratings were discordant, we sought to identify whether the participant's or psychiatrist's rating was more accurate. The results indicated a moderately strong statistically significant correlation between participant and clinician ratings. There was a moderate concordance between participant and clinician ratings on the ISRS. When the results were discordant, the participant ratings were assessed to be more accurate than the clinician rating over 70% of the time. The ISRS has distinct utility compared to existing scales due to the measurement of present symptom severity, capturing multiple clinical domains, and time efficiency and ease of use. Thus, it may be useful in clinical and research settings.


Assuntos
Transtornos Psicóticos , Esquizofrenia , Humanos , Esquizofrenia/diagnóstico , Autorrelato , Estudos de Viabilidade , Transtornos Psicóticos/diagnóstico , Afeto , Escalas de Graduação Psiquiátrica
4.
Dev Neurosci ; 45(6): 315-324, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37379808

RESUMO

Pediatric acute-onset neuropsychiatric syndrome (PANS) is an abrupt-onset neuropsychiatric disorder. PANS patients have an increased prevalence of comorbid autoimmune illness, most commonly arthritis. In addition, an estimated one-third of PANS patients present with low serum C4 protein, suggesting decreased production or increased consumption of C4 protein. To test the possibility that copy number (CN) variation contributes to risk of PANS illness, we compared mean total C4A and total C4B CN in ethnically matched subjects from PANS DNA samples and controls (192 cases and 182 controls). Longitudinal data from the Stanford PANS cohort (n = 121) were used to assess whether the time to juvenile idiopathic arthritis (JIA) or autoimmune disease (AI) onset was a function of total C4A or C4B CN. Lastly, we performed several hypothesis-generating analyses to explore the correlation between individual C4 gene variants, sex, specific genotypes, and age of PANS onset. Although the mean total C4A or C4B CN did not differ in PANS compared to controls, PANS patients with low C4B CN were at increased risk for subsequent JIA diagnosis (hazard ratio = 2.7, p value = 0.004). We also observed a possible increase in risk for AI in PANS patients and a possible correlation between lower C4B and PANS age of onset. An association between rheumatoid arthritis and low C4B CN has been reported previously. However, patients with PANS develop different types of JIA: enthesitis-related arthritis, spondyloarthritis, and psoriatic arthritis. This suggests that C4B plays a role that spans these arthritis types.


Assuntos
Artrite , Complemento C4b , Humanos , Criança , Complemento C4b/genética , Complemento C4a/genética , Dosagem de Genes , Genótipo , Artrite/genética
5.
Front Neurol ; 14: 1090747, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36908615

RESUMO

Background: The global prevalence of PASC is estimated to be present in 0·43 and based on the WHO estimation of 470 million worldwide COVID-19 infections, corresponds to around 200 million people experiencing long COVID symptoms. Despite this, its clinical features are not well-defined. Methods: We collected retrospective data from 140 patients with PASC in a post-COVID-19 clinic on demographics, risk factors, illness severity (graded as one-mild to five-severe), functional status, and 29 symptoms and principal component symptoms cluster analysis. The Institute of Medicine (IOM) 2015 criteria were used to determine the Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) phenotype. Findings: The median age was 47 years, 59.0% were female; 49.3% White, 17.2% Hispanic, 14.9% Asian, and 6.7% Black. Only 12.7% required hospitalization. Seventy-two (53.5%) patients had no known comorbid conditions. Forty-five (33.9%) were significantly debilitated. The median duration of symptoms was 285.5 days, and the number of symptoms was 12. The most common symptoms were fatigue (86.5%), post-exertional malaise (82.8%), brain fog (81.2%), unrefreshing sleep (76.7%), and lethargy (74.6%). Forty-three percent fit the criteria for ME/CFS, majority were female, and obesity (BMI > 30 Kg/m2) (P = 0.00377895) and worse functional status (P = 0.0110474) were significantly associated with ME/CFS. Interpretations: Most PASC patients evaluated at our clinic had no comorbid condition and were not hospitalized for acute COVID-19. One-third of patients experienced a severe decline in their functional status. About 43% had the ME/CFS subtype.

6.
J Psychiatr Res ; 161: 213-217, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36934603

RESUMO

Excess synaptic pruning during neurodevelopment has emerged as one of the leading hypotheses on the causal mechanism for schizophrenia. It proposes that excess synaptic elimination occurs during development before the formal onset of illness. Accordingly, synaptic deficits may be observable at all stages of illnesses, including in the early phases. The availability of [11C]UCB-J, the first-in-human in vivo synaptic marker, represents an opportunity for testing this hypothesis with a relatively high level of precision. The first two published [11C]UCB-J schizophrenia studies have documented significant, widespread reductions in binding in chronic patients. The present study tested the hypothesis that reductions are present in early-course patients. 18 subjects completed [11C]UCB-J PET scans, (nine with schizophrenia, average duration of illness of 3.36 years, and nine demographically-matched healthy individuals). We compared binding levels, quantified as non-displaceable specific binding (BPND), in a set of a priori-specified brain regions of interest (ROIs). Eight ROIs (left and right hippocampus, right superior temporal and Heschl's gyrus, left and right putamen, and right caudal and rostral middle frontal gyrus) showed large reductions meeting Bonferroni corrected significant levels, p < 0.0036. Exploratory, atlas-wide analyses confirmed widespread reductions in schizophrenia. We also observed significant positive correlations between binding levels and cognitive performance and a negative correlation with the severity of delusions. These results largely replicate findings from chronic patients, indicating that extensive [11C]UCB-J binding deficits are reliable and reproducible. Moreover, these results add to the growing evidence that excess synaptic pruning is a major disease mechanism for schizophrenia.


Assuntos
Esquizofrenia , Humanos , Esquizofrenia/diagnóstico por imagem , Lobo Temporal/metabolismo , Hipocampo/diagnóstico por imagem , Hipocampo/metabolismo , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Lobo Frontal/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Glicoproteínas de Membrana , Proteínas do Tecido Nervoso/metabolismo
7.
Transl Psychiatry ; 11(1): 486, 2021 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-34552056

RESUMO

Structural variation in the complement 4 gene (C4) confers genetic risk for schizophrenia. The variation includes numbers of the increased C4A copy number, which predicts increased C4A mRNA expression. C4-anaphylatoxin (C4-ana) is a C4 protein fragment released upon C4 protein activation that has the potential to change the blood-brain barrier (BBB). We hypothesized that elevated plasma levels of C4-ana occur in individuals with schizophrenia (iSCZ). Blood was collected from 15 iSCZ with illness duration < 5 years and from 14 healthy controls (HC). Plasma C4-ana was measured by radioimmunoassay. Other complement activation products C3-ana, C5-ana, and terminal complement complex (TCC) were also measured. Digital-droplet PCR was used to determine C4 gene structural variation state. Recombinant C4-ana was added to primary brain endothelial cells (BEC) and permeability was measured in vitro. C4-ana concentration was elevated in plasma from iSCZ compared to HC (mean = 654 ± 16 ng/mL, 557 ± 94 respectively, p = 0.01). The patients also carried more copies of the C4AL gene and demonstrated a positive correlation between plasma C4-ana concentrations and C4A gene copy number. Furthermore, C4-ana increased the permeability of a monolayer of BEC in vitro. Our findings are consistent with a specific role for C4A protein in schizophrenia and raise the possibility that its activation product, C4-ana, increases BBB permeability. Exploratory analyses suggest the novel hypothesis that the relationship between C4-ana levels and C4A gene copy number could also be altered in iSCZ, suggesting an interaction with unknown genetic and/or environmental risk factors.


Assuntos
Complemento C4 , Esquizofrenia , Complemento C4/genética , Complemento C4a/genética , Células Endoteliais , Predisposição Genética para Doença , Humanos , Esquizofrenia/sangue , Esquizofrenia/genética
8.
Nat Neurosci ; 24(2): 186-196, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33432196

RESUMO

Retrotransposons can cause somatic genome variation in the human nervous system, which is hypothesized to have relevance to brain development and neuropsychiatric disease. However, the detection of individual somatic mobile element insertions presents a difficult signal-to-noise problem. Using a machine-learning method (RetroSom) and deep whole-genome sequencing, we analyzed L1 and Alu retrotransposition in sorted neurons and glia from human brains. We characterized two brain-specific L1 insertions in neurons and glia from a donor with schizophrenia. There was anatomical distribution of the L1 insertions in neurons and glia across both hemispheres, indicating retrotransposition occurred during early embryogenesis. Both insertions were within the introns of genes (CNNM2 and FRMD4A) inside genomic loci associated with neuropsychiatric disorders. Proof-of-principle experiments revealed these L1 insertions significantly reduced gene expression. These results demonstrate that RetroSom has broad applications for studies of brain development and may provide insight into the possible pathological effects of somatic retrotransposition.


Assuntos
Aprendizado de Máquina , Mutagênese Insercional/genética , Neuroglia , Neurônios , Proteínas Adaptadoras de Transdução de Sinal/genética , Adulto , Proteínas de Transporte de Cátions/genética , Desenvolvimento Embrionário/genética , Feminino , Genoma/genética , Células HeLa , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Elementos Nucleotídeos Longos e Dispersos , Transtornos Mentais/genética , Gravidez , Retroelementos , Esquizofrenia/genética
9.
Acad Psychiatry ; 44(1): 86-89, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31642050

RESUMO

OBJECTIVE: Psychiatry residents must learn to incorporate new information into clinical practice as the field quickly evolves. The authors developed a practice-based workshop grounded in active learning principles on the inpatient psychiatric unit. METHODS: Residents rotating on inpatient services observed a patient interview, then brainstormed learner-driven learning objectives. They each independently researched selected topics, then utilized peer instruction and discussion grounded in the clinical case. Topic areas covered over a year were tracked and residents' experiences were surveyed. RESULTS: The material covered included evidence-based treatments, neuroscience, cultural, and systems psychiatry. Residents rated the workshop as highly effective and engaging (91% and 96%, respectively, on Likert Scale) and positively on the Tutorial Group Effectiveness Instrument (3.8 ± 0.6 for cognitive aspects, 3.2 ± 0.7 for motivational aspects, and 2.7 ± 0.6 for demotivational aspects). CONCLUSIONS: This case-based and learner-driven peer teaching model based on an active learning model allows for quick integration of new material into the curriculum with resident satisfaction.


Assuntos
Currículo , Capacitação em Serviço/métodos , Internato e Residência , Aprendizagem Baseada em Problemas/métodos , Unidade Hospitalar de Psiquiatria , Psiquiatria/educação , Adulto , Humanos , Pacientes Internados , Grupo Associado
10.
Addiction ; 111(7): 1293-8, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27073140

RESUMO

BACKGROUND AND AIMS: One of the challenges of international alcohol research and policy is the variability in and lack of knowledge of how governments in different nations define a standard drink and low-risk drinking. This study gathered such information from governmental agencies in 37 countries. METHODS: A pool of 75 countries that might have definitions was created using World Health Organization (WHO) information and the authors' own judgement. Structured internet searches of relevant terms for each country were supplemented by efforts to contact government agencies directly and to consult with alcohol experts in the country. RESULTS: Most of the 75 national governments examined were not identified as having adopted a standard drink definition. Among the 37 that were so identified, the modal standard drink size was 10 g pure ethanol, but variation was wide (8-20 g). Significant variability was also evident for low-risk drinking guidelines, ranging from 10-42 g per day for women and 10-56 g per day for men to 98-140 g per week for women and 150-280 g per week for men. CONCLUSIONS: Researchers working and communicating across national boundaries should be sensitive to the substantial variability in 'standard' drink definitions and low-risk drinking guidelines. The potential impact of guidelines, both in general and in specific national cases, remains an important question for public health research.


Assuntos
Consumo de Bebidas Alcoólicas , Bebidas Alcoólicas , Governo , Guias como Assunto , Depressores do Sistema Nervoso Central , Etanol , Humanos
11.
Nucleus ; 6(3): 203-11, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25807068

RESUMO

The nucleoskeleton contains mainly nuclear intermediate filaments made of lamin proteins. Lamins provide nuclear structure and also play a role in various nuclear processes including signal transduction, transcription regulation and chromatin organization. The disparate functions of lamins may be related to the intrinsic disorder of the tail domains, which allows for altered and promiscuous binding. Here, we show modulation of lamin tail domain structures in the presence of divalent cations. We utilize changes in fluorescence of tryptophan residues within the Ig-fold flanked by disordered regions to experimentally measure protein thermodynamics. Using spectroscopy experiments and molecular dynamics simulations, we show that the tail domain of lamin B1 shows enhanced association with both Ca(2+) and Mg(2+) compared to the tail domain of lamin A. Binding curves show a similar KD between protein and ion (250-300 µM) for both proteins with both ions. However, we observe a maximum binding of ions to lamin B1 tail domain which is 2-3 times greater than that for lamin A tail domain by both experiment and simulation. Using simulations, we show that divalent ion association alters the Ig-fold by pinning flanking regions. With cells in culture, we observe altered lamin B1 organization in the presence of excess Mg(2+) more so than for lamin A. We suggest that the differential sensitivity to divalent cations contributes to the vastly different functionalities and binding of the 2 proteins.


Assuntos
Cálcio/química , Lamina Tipo A/química , Lamina Tipo B/química , Magnésio/química , Matriz Nuclear/metabolismo , Sequência de Aminoácidos , Cálcio/metabolismo , Cátions Bivalentes , Escherichia coli/genética , Escherichia coli/metabolismo , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Expressão Gênica , Humanos , Cinética , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Lamina Tipo B/genética , Lamina Tipo B/metabolismo , Magnésio/metabolismo , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Matriz Nuclear/ultraestrutura , Cultura Primária de Células , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Espectrometria de Fluorescência , Termodinâmica
12.
Biophys Chem ; 195: 43-8, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25194277

RESUMO

Hutchinson-Gilford progeria syndrome is a premature aging disorder associated with the expression of ∆50 lamin A (∆50LA), a mutant form of the nuclear structural protein lamin A (LA). ∆50LA is missing 50 amino acids from the tail domain and retains a C-terminal farnesyl group that is cleaved from the wild-type LA. Many of the cellular pathologies of HGPS are thought to be a consequence of protein-membrane association mediated by the retained farnesyl group. To better characterize the protein-membrane interface, we quantified binding of purified recombinant ∆50LA tail domain (∆50LA-TD) to tethered bilayer membranes composed of phosphatidylserine and phosphocholine using surface plasmon resonance. Farnesylated ∆50LA-TD binds to the membrane interface only in the presence of Ca(2+) or Mg(2+) at physiological ionic strength. At extremely low ionic strength, both the farnesylated and non-farnesylated forms of ∆50LA-TD bind to the membrane surface in amounts that exceed those expected for a densely packed protein monolayer. Interestingly, the wild-type LA-TD with no farnesylation also associates with membranes at low ionic strength but forms only a single layer. We suggest that electrostatic interactions are mediated by charge clusters with a net positive charge that we calculate on the surface of the LA-TDs. These studies suggest that the accumulation of ∆50LA at the inner nuclear membrane observed in cells is due to a combination of aggregation and membrane association rather than simple membrane binding; electrostatics plays an important role in mediating this association.


Assuntos
Lamina Tipo A/química , Progéria/patologia , Cálcio/química , Humanos , Íons/química , Lamina Tipo A/metabolismo , Luz , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Magnésio/química , Simulação de Dinâmica Molecular , Concentração Osmolar , Fosfatidilserinas/química , Fosforilcolina/química , Progéria/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Espalhamento de Radiação , Ressonância de Plasmônio de Superfície
13.
Biophys J ; 104(10): 2246-53, 2013 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-23708364

RESUMO

Lamin proteins contribute to nuclear structure and function, primarily at the inner nuclear membrane. The posttranslational processing pathway of lamin A includes farnesylation of the C-terminus, likely to increase membrane association, and subsequent proteolytic cleavage of the C-terminus. Hutchinson Gilford progeria syndrome is a premature aging disorder wherein a mutant version of lamin A, Δ50 lamin A, retains its farnesylation. We report here that membrane association of farnesylated Δ50 lamin A tail domains requires calcium. Experimental evidence and molecular dynamics simulations collectively suggest that the farnesyl group is sequestered within a hydrophobic region in the tail domain in the absence of calcium. Calcium binds to the tail domain with an affinity KD ≈ 250 µM where it alters the structure of the Ig-fold and increases the solvent accessibility of the C-terminus. In 2 mM CaCl2, the affinity of the farnesylated protein to a synthetic membrane is KD ≈ 2 µM, as measured with surface plasmon resonance, but showed a combination of aggregation and binding. Membrane binding in the absence of calcium could not be detected. We suggest that a conformational change induced in Δ50 lamin A with divalent cations plays a regulatory role in the posttranslational processing of lamin A, which may be important in disease pathogenesis.


Assuntos
Cálcio/metabolismo , Lamina Tipo A/química , Bicamadas Lipídicas/metabolismo , Sequência de Aminoácidos , Animais , Membrana Celular/metabolismo , Humanos , Lamina Tipo A/metabolismo , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Ligação Proteica , Prenilação de Proteína , Estrutura Terciária de Proteína
14.
Nucleus ; 2(6): 570-9, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22127259

RESUMO

Computational image analysis is used in many areas of biological and medical research, but advanced techniques including machine learning remain underutilized. Here, we used automated segmentation and shape analyses, with pre-defined features and with computer generated components, to compare nuclei from various premature aging disorders caused by alterations in nuclear proteins. We considered cells from patients with Hutchinson-Gilford progeria syndrome (HGPS) with an altered nucleoskeletal protein; a mouse model of XFE progeroid syndrome caused by a deficiency of ERCC1-XPF DNA repair nuclease; and patients with Werner syndrome (WS) lacking a functional WRN exonuclease and helicase protein. Using feature space analysis, including circularity, eccentricity, and solidity, we found that XFE nuclei were larger and significantly more elongated than control nuclei. HGPS nuclei were smaller and rounder than the control nuclei with features suggesting small bumps. WS nuclei did not show any significant shape changes from control. We also performed principle component analysis (PCA) and a geometric, contour based metric. PCA allowed direct visualization of morphological changes in diseased nuclei, whereas standard, feature-based approaches required pre-defined parameters and indirect interpretation of multiple parameters. Both methods yielded similar results, but PCA proves to be a powerful pre-analysis methodology for unknown systems.


Assuntos
Núcleo Celular/patologia , Síndrome de Cockayne/patologia , Processamento de Imagem Assistida por Computador , Progéria/patologia , Síndrome de Werner/patologia , Adulto , Animais , Núcleo Celular/genética , Núcleo Celular/metabolismo , Criança , Síndrome de Cockayne/genética , Síndrome de Cockayne/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endonucleases/genética , Endonucleases/metabolismo , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/metabolismo , Humanos , Masculino , Camundongos , Camundongos Knockout , Progéria/genética , Progéria/metabolismo , RecQ Helicases/genética , RecQ Helicases/metabolismo , Síndrome de Werner/genética , Síndrome de Werner/metabolismo , Helicase da Síndrome de Werner
15.
J Struct Biol ; 175(3): 425-33, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21635954

RESUMO

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging syndrome caused by the expression and accumulation of a mutant form of lamin A, Δ50 lamin A. As a component of the cell's nucleoskeleton, lamin A plays an important role in the mechanical stabilization of the nuclear envelope and in other nuclear functions. It is largely unknown how the characteristic 50 amino acid deletion affects the conformation of the mostly intrinsically disordered tail domain of lamin A. Here we perform replica exchange molecular dynamics simulations of the tail domain and determine an ensemble of semi-stable structures. Based on these structures we show that the ZMPSTE 24 cleavage site on the precursor form of the lamin A tail domain orients itself in such a way as to facilitate cleavage during the maturation process. We confirm our simulated structures by comparing the thermodynamic properties of the ensemble structures to in vitro stability measurements. Using this combination of experimental and computational techniques, we compare the size, heterogeneity of size, thermodynamic stability of the Ig-fold, as well as the mechanisms of force-induced denaturation. Our data shows that the Δ50 lamin A tail domain is more compact and displays less heterogeneity than the mature lamin A tail domain. Altogether these results suggest that the altered structure and stability of the tail domain can explain changed protein-protein and protein-DNA interactions and may represent an etiology of the disease. Also, this study provides the first molecular structure(s) of the lamin A tail domain, which is confirmed by thermodynamic tests in experiment.


Assuntos
Lamina Tipo A/química , Lamina Tipo A/genética , Progéria/genética , Sequência de Aminoácidos , Animais , Fluorometria , Camundongos , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Mutação , Estabilidade Proteica , Estrutura Secundária de Proteína
17.
Cell Mol Bioeng ; 3(2): 139-150, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20563238

RESUMO

Nesprins are located at the outer and inner membranes of the nuclear envelope and help link the cytoskeleton to the nucleoskeleton. Nesprin-1α, located at the inner nuclear membrane, binds to A-type lamins and emerin and has homology to spectrin-repeat proteins. However, the mechanical and thermodynamic properties of the spectrin-like repeats (SLRs) of nesprin-1α and the potential structural contributions of the unique central domain were untested. In other spectrin superfamily proteins, tandem spectrin-repeat domains undergo cooperatively coupled folding and unfolding. We hypothesized that the large central domain, which interrupts SLRs and is conserved in other nesprin isoforms, might confer unique structural properties. To test this model we measured the thermal unfolding of nesprin-1α fragments using circular dichroism and dynamic light scattering. The SLRs in nesprin-1α were found to have structural and thermodynamic properties typical of spectrins. The central domain had relatively little secondary structure as an isolated fragment, but significantly stabilized larger SLR-containing molecules by increasing their overall helicity, thermal stability and cooperativity of folding. We suggest this domain, now termed the 'adaptive' domain (AD), also strengthens dimerization and inhibits unfolding. Further engineering of the isolated AD, and AD-containing nesprin molecules, may yield new information about the higher-order association of cooperative protein motifs.

18.
Microcirculation ; 17(3): 179-91, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20374482

RESUMO

Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson-Gilford progeria syndrome, is reviewed specifically as the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation as visualization in situ is difficult. This integrated approach to study--including medicine, molecular and cell biology, biophysics and engineering--provides a unique understanding of multi-scale interactions in the microcirculation.


Assuntos
Microcirculação/fisiologia , Animais , Fenômenos Biomecânicos , Doenças Cardiovasculares/genética , Doenças Cardiovasculares/fisiopatologia , Núcleo Celular/fisiologia , Hemodinâmica , Hemorreologia , Humanos , Lamina Tipo A/genética , Lamina Tipo A/fisiologia , Mecanotransdução Celular , Modelos Cardiovasculares , Mutação , Progéria/genética , Progéria/fisiopatologia , Transdução de Sinais
19.
Phys Rev Lett ; 96(18): 186105, 2006 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-16712378

RESUMO

Dynamical response of nanomechanical cantilever structures immersed in a viscous fluid is important to in vitro single-molecule force spectroscopy, biomolecular recognition of disease-specific proteins, and the study of microscopic protein dynamics. Here we study the stochastic response of biofunctionalized nanomechanical cantilever beams in a viscous fluid. Using the fluctuation-dissipation theorem we derive an exact expression for the spectral density of displacement and a linear approximation for resonance frequency shift. We find that in a viscous solution the frequency shift of the nanoscale cantilever is determined by surface stress generated by biomolecular interaction with negligible contributions from mass loading due to the biomolecules.

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