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1.
Behav Brain Res ; 429: 113919, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35525338

RESUMO

Interest in the role of sex as a biological variable has increased, including a mandate for the study of both sexes in NIH-funded research. As sex differences exist in both human chronic pain conditions and rodent models of nociception, it is critical to understand the impact of sex in nociceptive assays. Choice-based thermal nociceptive tests permit the study of avoidance responses to thermal stimuli compared to traditional nociceptive assays, which measure nocifensive reactions. However, to date no comparison of male and female responses to choice-based tests has been published. Herein, we examined the effect of sex on two choice-based thermal nociceptive tests, the thermal gradient test and the temperature place preference test, in adult rats. The activation of a 10 °C-to-47 °C thermal gradient results in an increase in time spent in the 10 °C zone in females, compared to a reduction in males. Additionally, in a temperature place preference test pairing a surface temperature of 22 °C with either 5 °C, 10 °C, 47 °C, or 50 °C, females appeared to have overall greater tolerance for non-ambient temperatures. Males spent less than 50% of their time in every non-22 °C zone, whereas in females this was only observed when testing 5 °C and 50 °C. Together, these results suggest that male rats show more avoidance behavior than females to both hot and cold non-ambient temperatures when given free access to multiple zones, including at milder temperatures than those typically used to evoke a nociceptive response in traditional hot and cold plate tests.


Assuntos
Limiar da Dor , Caracteres Sexuais , Animais , Feminino , Temperatura Alta , Masculino , Nociceptividade/fisiologia , Medição da Dor/métodos , Limiar da Dor/fisiologia , Ratos
2.
Dev Psychobiol ; 63(6): e22186, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34423851

RESUMO

Data in both humans and preclinical animal models clearly indicate drug exposure during adolescence, when the "reward" circuitry of the brain develops, increases the risk of substance use and other mental health disorders later in life. Human data indicate that different neural and behavioral sequelae can be observed in early versus late adolescence. However, most studies with rodent models examine a single adolescent age compared to a mature adult age, and often only in males. Herein, we sought to determine whether the acute response to the opioid morphine would also differ across adolescence, and by sex. By quantifying Fos positive cells, a proxy for neural activity, at different stages during adolescence (pre-, early, mid-, and late adolescence) and in multiple reward regions (prefrontal cortex, nucleus accumbens, caudate/putamen), we determined that the neural response to acute morphine is highly dependent on adolescent age, sex, and brain region. These data suggest that heterogeneity in the consequences of adolescent opioid exposure may be due to age- and sex-specific developmental profiles in individual reward processing regions. In future studies, it will be important to add age within adolescence as an independent variable for a holistic view of healthy or abnormal reward-related neural development.


Assuntos
Morfina , Núcleo Accumbens , Animais , Encéfalo , Feminino , Masculino , Morfina/farmacologia , Núcleo Accumbens/metabolismo , Córtex Pré-Frontal/fisiologia , Recompensa
3.
J Neurosci Methods ; 348: 108982, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33091429

RESUMO

BACKGROUND: The use of immunohistochemistry to quantify neural markers in various brain regions is a staple of neuroscience research. Numerous programs exist to automate quantification, but manual assignment of regions of interest (ROIs) within individual brain sections remains time consuming and can introduce interobserver variability. NEW METHOD: We have developed a novel open source FIJI-based immunohistochemical data analysis pipeline, Atlas-Based Analysis (ABA). ABA uses landmark-based image warping to adjust the experimental image to closely align with a published rat brain atlas. c-Fos positive cells are then quantified within predetermined ROI coordinates derived from the brain atlas. Image warping adjusts for natural variation in brain sections to ensure reliable alignment of ROIs for data analysis. This pipeline can be adapted for new atlases, landmarks, ROIs, and quantification measurements. RESULTS: ABA permits rapid quantification of immunoreactivity in multiple ROIs and produces results with high levels of interobserver consistency. COMPARISON WITH EXISTING METHODS: Compared to manual ROI designation, ABA reduces total analysis time by ∼70%. With correct use of landmarks for image warping, ABA produces similar results to manually drawn ROIs, results in no interobserver variability, and maintains c-Fos+ pixel dimensions. CONCLUSIONS: ABA reduces time to obtain reliable results when performing automated immunoreactivity quantification and allows multiple users to analyze data without compromising the reliability of data obtained.


Assuntos
Mapeamento Encefálico , Encéfalo , Encéfalo/diagnóstico por imagem , Técnicas Histológicas , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Variações Dependentes do Observador , Reprodutibilidade dos Testes
4.
Nat Commun ; 9(1): 1476, 2018 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-29662058

RESUMO

The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.

5.
Mol Psychiatry ; 22(4): 625-633, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27166760

RESUMO

Contactin genes CNTN5 and CNTN6 code for neuronal cell adhesion molecules that promote neurite outgrowth in sensory-motor neuronal pathways. Mutations of CNTN5 and CNTN6 have previously been reported in individuals with autism spectrum disorders (ASDs), but very little is known on their prevalence and clinical impact. In this study, we identified CNTN5 and CNTN6 deleterious variants in individuals with ASD. Among the carriers, a girl with ASD and attention-deficit/hyperactivity disorder was carrying five copies of CNTN5. For CNTN6, both deletions (6/1534 ASD vs 1/8936 controls; P=0.00006) and private coding sequence variants (18/501 ASD vs 535/33480 controls; P=0.0005) were enriched in individuals with ASD. Among the rare CNTN6 variants, two deletions were transmitted by fathers diagnosed with ASD, one stop mutation CNTN6W923X was transmitted by a mother to her two sons with ASD and one variant CNTN6P770L was found de novo in a boy with ASD. Clinical investigations of the patients carrying CNTN5 or CNTN6 variants showed that they were hypersensitive to sounds (a condition called hyperacusis) and displayed changes in wave latency within the auditory pathway. These results reinforce the hypothesis of abnormal neuronal connectivity in the pathophysiology of ASD and shed new light on the genes that increase risk for abnormal sensory perception in ASD.


Assuntos
Percepção Auditiva/genética , Transtorno do Espectro Autista/genética , Contactinas/genética , Adolescente , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/genética , Transtorno do Espectro Autista/metabolismo , Criança , Contactinas/metabolismo , Variações do Número de Cópias de DNA , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Mutação , Polimorfismo de Nucleotídeo Único
6.
J Nutr Health Aging ; 20(1): 48-55, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26728933

RESUMO

This study examined the effectiveness of three different learning methods: trial and error learning (TE), errorless learning (EL) and learning by modeling with spaced retrieval (MR) on the relearning process of IADL in mild-to-moderately severe Alzheimer's Dementia (AD) patients (n=52), using a 6-weeks randomized controlled trial design. The participants had to relearn three IADLs. Repeated-measure analyses during pre-intervention, post-intervention and 1-month delayed sessions were performed. All three learning methods were found to have similar efficiency. However, the intervention produced greater improvements in the actual performance of the IADL tasks than on their explicit knowledge. This study confirms that the relearning of IADL is possible with AD patients through individualized interventions, and that the improvements can be maintained even after the intervention.


Assuntos
Atividades Cotidianas , Doença de Alzheimer/reabilitação , Aprendizagem , Idoso , Idoso de 80 Anos ou mais , Demência , Feminino , Humanos , Masculino , Memória
7.
Nat Mater ; 13(1): 74-80, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24270583

RESUMO

Combining functionalities in devices with high performances is a great challenge that rests on the discovery and optimization of materials. In this framework, layered oxides are attractive for numerous purposes, from energy conversion and storage to magnetic and electric properties. We demonstrate here the oxygen storage ability of ferroelectric LuFe2O4+x within a large x range (from 0 to 0.5) and its cycling possibility. The combination of thermogravimetric analyses, X-ray diffraction and transmission electron microscopy evidences a complex oxygen intercalation/de-intercalation process with several intermediate metastable states. This topotactic mechanism is mainly governed by nanoscale structures involving a shift of the cationic layers. The ferrite is highly promising because absorption begins at a low temperature (~=200 °C), occurs in a low oxygen pressure and the uptake of oxygen is reversible without altering the quality of the crystals. The storage/release of oxygen coupled to the transport and magnetic properties of LnFe2O4 opens the door to new tunable multifunctional applications.

8.
Public Health Action ; 3(2): 175-9, 2013 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-26393023

RESUMO

SETTING: A non-governmental organization, Dignitas International, working in partnership with the Ministry of Health in Malawi, adopted innovative, low-technology methods to collect, capture, and manage patient-level antiretroviral therapy (ART) data in a district database covering 26 remote low-resource facilities in Zomba District, Malawi. OBJECTIVE: To establish a longitudinal, observational database of routinely collected program data that could serve as a program monitoring and evaluation tool as well as a platform to conduct effective operational research. DESIGN: This article describes the processes developed for digital capture of paper-based ART clinical records at health facilities and updating them in a central electronic database. It documents and focuses on lessons learned during the implementation and review of processes. CONCLUSIONS: Data quality can only be ensured with regular review of, and compliance with, clearly delineated workflow protocols and adequate staffing and supervision. Through the implementation of this procedure, we expect to improve data quality, completeness, and use of routine ART clinical data in low-resource settings.

9.
Cancer Radiother ; 16(8): 674-80, 2012 Dec.
Artigo em Francês | MEDLINE | ID: mdl-23103447

RESUMO

PURPOSE: To report retrospective long-term results of historical experience of breast radiotherapy (RT) including external beam radiotherapy (EBRT) followed by low dose rate (LDR) brachytherapy. PATIENTS AND METHODS: Between 1971 and 1983, at our service 474 breast cancer patients underwent exclusive conserving radiotherapy treatment. The RT included an initial external irradiation followed by interstitial LDR brachytherapy (37Gy) to the residual tumour. The local regional nodes received 47.5Gy followed by a 15Gy boost delivered to the mammary nodes internal (IMN) and 25Gy axilla. RESULTS: Median follow-up was 139months (8-342). There were 40 T1, 356 T2, and 78 T3. Local recurrences (LR) were observed in 20% of cases. The rate of recurrences free at 5, 10, 15 and 20years were 86%, 77%, 73% and 67% respectively. At 5, 10, 15 and 20-year, the disease-free survival rates were 63%, 42%, 32% and 24%. Overall survival rates at 5, 10, 15 and 20-years were 75%, 53%, 34% and 25% respectively. CONCLUSION: Although the historical retrospective character of these series, it is interesting to have this experience and to analyse it according to our new knowledge and advances. The described technique was a standard for many years and could be still used in some cases.


Assuntos
Braquiterapia , Neoplasias da Mama/mortalidade , Neoplasias da Mama/radioterapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/patologia , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Linfonodos/patologia , Linfonodos/efeitos da radiação , Pessoa de Meia-Idade , Metástase Neoplásica , Recidiva Local de Neoplasia/epidemiologia , Dosagem Radioterapêutica , Estudos Retrospectivos , Adulto Jovem
11.
Phys Rev Lett ; 105(23): 237203, 2010 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-21231500

RESUMO

The electronic ferroelectric lutetium ferrite (LuFe(2)O(4)) was studied by x-ray diffraction as a function of pressure. Pressure is shown to induce an irreversible rhombohedral to orthorhombic transition leading to a supercell determined by the combination of electron and synchrotron x-ray diffraction. This new configuration is proposed to be charge ordered in agreement with the results of resistivity measurements.

12.
Skin Res Technol ; 14(1): 71-6, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18211604

RESUMO

BACKGROUND/PURPOSE: Cutaneous fibrosis is the quite mandatory sequela after a breast cancer treated by radiotherapy and it induces more or less important functional troubles. The LPG technique is a technique of mechanical massage that allows skin mobilization by folding/unfolding. The aim of this study was to evaluate the changes on irradiated skin before and after LPG treatment by clinical and skin replica analysis. METHODS: Twenty women, 43-55 years old, who had been treated from 6 to 16 months before, for breast cancer with a conservative surgery and radiotherapy, had been enrolled in the trial. They were divided into two groups after randomization: the first group was LPG treated three times a week for 1 month; the second group was only placed under medical supervision. The clinical criteria studied were systematically studied before (T0), at the end of treatment (T1) and 1 month after the end of treatment (T2): pain, itching, skin dryness, erythema, skin infiltration, feeling of tightness and of induration of the skin. Softening of the skin was assessed at T1 and T2. Cutaneous replica was performed on the internal upper 1/4 of each breast with silicone material before, after and 1 month later after the end of the treatment. After polymerization, the replica was stored and then blindly analyzed by image analysis software. The following parameters were systematically measured: average skin roughness, average of wrinkles' depth and residual length, wrinkle number and the space between them. RESULTS: Clinically, the LPG treatment induced a decrease of erythema (10% of the patients vs. 40% before treatment), a decrease of pain and pruritus (10% vs. 20% and 40%, respectively) and a decrease of the feeling of induration of the skin (10% of the patients vs. 70% before treatment). Furthermore, a skin-softening sensation was noted by seven patients vs. one in the control group. Replica shows an increase of roughness and of furrow depth without any change in the residual length and an increase in the space between the wrinkles, whose number decreases. CONCLUSION: This study confirms the impact of the clinical sequelae induced on skin after radiotherapy and shows improvement of the clinical signs after treatment by the LPG technique. The latter induces changes of micro relief, suggesting a softening effect on the skin. These preliminary results have to be confirmed on a more important group of patients.


Assuntos
Neoplasias da Mama/radioterapia , Mama/patologia , Fibrose/terapia , Massagem/métodos , Radiodermite/terapia , Dermatopatias/terapia , Pele/efeitos da radiação , Adulto , Análise de Variância , Neoplasias da Mama/cirurgia , Elasticidade , Feminino , Fibrose/etiologia , Humanos , Pessoa de Meia-Idade , Dor/etiologia , Estudos Prospectivos , Prurido/etiologia , Pele/patologia , Resultado do Tratamento
13.
Can J Gastroenterol ; 21(7): 453-5, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17637949

RESUMO

The present report describes a young woman with no previous gastrointestinal complaints who was initially diagnosed with postinfective irritable bowel syndrome (IBS) after a confirmed case of Campylobacter jejuni enteritis. However, because of persistent diarrhea, new-onset bloating and the development of iron and vitamin deficiencies, serological markers for celiac disease (CD) were evaluated. A positive tissue transglutaminase immunoglobulin A antibody test and repeat endoscopy with duodenal biopsy showing a Marsh IIIa lesion confirmed the diagnosis of CD. Infectious gastroenteritis is a well-established risk factor for the development of IBS, and there is recent evidence that it could play a role in the initiation and exacerbation of inflammatory bowel disease. The present case suggests that the clinical expression of CD can be unmasked by an acute gastrointestinal infection and supports the hypothesis that environmental factors other than gliadin may play a role in the clinical onset of CD in a genetically susceptible host. The increasing availability of serological testing and upper endoscopy has led to increasingly frequent diagnoses of CD and recognition that it may mimic IBS. The present case findings suggest that CD should be considered in the differential diagnosis of persistent IBS-like symptoms after an episode of infectious gastroenteritis.


Assuntos
Infecções por Campylobacter/diagnóstico , Campylobacter jejuni , Doença Celíaca/diagnóstico , Enterite/diagnóstico , Síndrome do Intestino Irritável/diagnóstico , Adulto , Infecções por Campylobacter/complicações , Doença Celíaca/complicações , Diagnóstico Diferencial , Dieta , Duodenoscopia , Enterite/complicações , Fezes/microbiologia , Feminino , Humanos , Síndrome do Intestino Irritável/complicações
14.
Neurogastroenterol Motil ; 19(5): 349-64, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17509017

RESUMO

Crohn's disease associated dysmotility has been attributed to fibrosis and damage to enteric nerves but injury to interstitial cells of Cajal (ICC) could also be involved. We assessed ICC in specimens obtained from patients with Crohn's disease and determined the relation between ICC and the inflammatory infiltrate, particularly mast cells (MC) using quantitative immunohistochemistry and electron microscopy. Ultrastructural injury to ICC was patchy in all ICC subtypes but ICC-Auerbach's plexus (AP) showed damage more frequently, i.e. swelling of mitochondria, decreased electron density, autophagosomes and partial depletion of the cytoplasm. Light microscopy confirmed a significant decrease in c-kit immunoreactivity for ICC-AP and an increased number of MC in the muscularis externa. Electron microscopy showed MC exhibiting piecemeal degranulation and making frequent and selective membrane-to-membrane contact with all types of injured ICC which suggests chronic release of granule content to affect ICC. Extent of ICC injury was not associated with duration of the disease. In conclusion, ultrastructural injury and loss of ICC-AP is evident in Crohn's disease. Epidemiological and morphological data suggest that ICC have the capacity to regenerate in spite of the chronic insult. The muscularis hosts a marked number of MC that exhibit piecemeal degranulation associated with ICC and may facilitate ICC maintenance.


Assuntos
Doença de Crohn/patologia , Sistema Nervoso Entérico/ultraestrutura , Íleo/ultraestrutura , Mastócitos/metabolismo , Plexo Mientérico/ultraestrutura , Adolescente , Adulto , Animais , Humanos , Íleo/metabolismo , Mastócitos/ultraestrutura , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Proteínas Proto-Oncogênicas c-kit/metabolismo
15.
J Neurochem ; 102(2): 479-92, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17419810

RESUMO

Nicotinic acetylcholine receptors play important roles in numerous cognitive processes as well as in several debilitating central nervous system (CNS) disorders. In order to fully elucidate the diverse roles of nicotinic acetylcholine receptors in CNS function and dysfunction, a detailed knowledge of their cellular and subcellular localizations is essential. To date, methods to precisely localize nicotinic acetylcholine receptors in the CNS have predominantly relied on the use of anti-receptor subunit antibodies. Although data obtained by immunohistology and immunoblotting are generally in accordance with ligand binding studies, some discrepancies remain, in particular with electrophysiological findings. In this context, nicotinic acetylcholine receptor subunit-deficient mice should be ideal tools for testing the specificity of subunit-directed antibodies. Here, we used standard protocols for immunohistochemistry and western blotting to examine the antibodies raised against the alpha3-, alpha4-, alpha7-, beta2-, and beta4-nicotinic acetylcholine receptor subunits on brain tissues of the respective knock-out mice. Unexpectedly, for each of the antibodies tested, immunoreactivity was the same in wild-type and knock-out mice. These data imply that, under commonly used conditions, these antibodies are not suited for immunolocalization. Thus, particular caution should be exerted with regards to the experimental approach used to visualize nicotinic acetylcholine receptors in the brain.


Assuntos
Anticorpos/metabolismo , Especificidade de Anticorpos/imunologia , Imuno-Histoquímica/métodos , Neuroquímica/métodos , Subunidades Proteicas/imunologia , Receptores Nicotínicos/imunologia , Acetilcolina/metabolismo , Animais , Animais Recém-Nascidos , Anticorpos/química , Western Blotting , Bungarotoxinas/metabolismo , Córtex Cerebral/anatomia & histologia , Córtex Cerebral/imunologia , Córtex Cerebral/metabolismo , Eletroforese em Gel Bidimensional , Feminino , Hipocampo/anatomia & histologia , Hipocampo/imunologia , Hipocampo/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/imunologia , Neurônios/metabolismo , Subunidades Proteicas/análise , Subunidades Proteicas/genética , Receptores Nicotínicos/análise , Receptores Nicotínicos/genética , Transmissão Sináptica/imunologia
16.
J Physiol ; 580(Pt. 2): 617-28, 2007 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-17272352

RESUMO

Although data relating to muscle glycogen are interpreted as showing it is homogenous when quantified biochemically, it is actually in granules in specific subcellular locations. We hypothesized that postexercise restoration of muscle glycogen would occur initially by an increase in granule number followed by an increase in size, and also that restoration would differ in various subcellular locations. Five men performed prolonged exercise and had muscle biopsies taken at 0, 4, 24 and 48 h of recovery. We quantified granule number and size as well as the total volume of glycogen in the subsarcolemmal and the intra- and intermyofibrillar regions, using transmission electron microscopy. Muscle glycogen was reduced to 36 +/- 8.3 mmol glucosyl units (kg dry weight)(-1) at exhaustion, and was preferentially depleted and subsequently repleted in the intramyofibrillar space. The repletion rate was greatest in the first 4 h; this was associated with a 186% increase in number (P < or = 0.05) and no change in particle size (P > or = 0.05). From 4 h to 48 h, there was an increase in particle size (P < or = 0.05) but not number (P > or = 0.05). Net rate of G volume synthesis per unit area was 50% greater (P < or = 0.05) in the subsarcolemmal than the myofibrillar compartment. Conversely, the net rate of single-particle volume synthesis was greater (P < or = 0.05) in the myofibrillar than the subsarcolemmal compartment. Glycogen granules varied in size and number depending on location, and in all compartments resynthesis of glycogen was characterized initially by an increase in granule number and later by an increase in size.


Assuntos
Exercício Físico/fisiologia , Glicogênio/metabolismo , Músculo Esquelético/metabolismo , Adulto , Glicogênio/ultraestrutura , Humanos , Masculino , Músculo Esquelético/ultraestrutura , Tamanho da Partícula , Fatores de Tempo
18.
Resuscitation ; 63(2): 175-81, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15531069

RESUMO

The positive effect of early defibrillation on survival from cardiac arrest has been demonstrated. We describe the use of AEDs over 1 year following the training of flight attendants. Air France and the University of Paris XII together designed a 1 year training programme for 14000 flight attendants. The university emergency departments (SAMU) provided 250 instructors. AEDs training and certification was conducted for crew members between November 2001 and November 2002. By January 2003, all aircraft were fully equipped with AEDs. All cases of cardiac arrest that occurred during the study were reviewed comprehensively. Comments from the crew were collected. Twelve cardiac arrests were reported between November 2002 and November 2003 out of 4194 cases of emergency care delivered to passengers. Shock treatment was advised initially in 5/12 cases. The survival rate after in-flight cardiac arrest was 3/12. The survival rate at discharge from hospital following in flight shock was 2/5. No complications arose from the use of AEDs. Training by professionals gave the flight attendants confidence and allowed for the survival of two young passengers. Our study highlights the ability of flight attendants to give better onboard care for the future. The next step is to consolidate the network between in-flight care and the medical dispatch centre in Paris.


Assuntos
Medicina Aeroespacial , Desfibriladores , Parada Cardíaca/terapia , Adulto , Medicina Aeroespacial/educação , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Paris
19.
Eur J Neurosci ; 20(8): 2022-30, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15450081

RESUMO

Many neurological pathologies are related to misfolded proteins. During folding and assembly in the endoplasmic reticulum, the nicotinic acetylcholine receptor (nAChR) subunits undergo several conformational changes to acquire the ability to bind ligands. After folding and maturation, by mechanisms largely unknown, receptors are exported to the cell surface. We investigated the maturational role of the extracellular C-terminal segment located at the boundary between the extracellular and the transmembrane domains. In the functional chimeric alpha7-5HT3A receptor used as a model system, amino acids from the C-terminal segment were successively deleted or mutated. Upon progressive shortening of the peptide we observed less and less alpha-bungarotoxin binding sites until no sites could be detected when the entire peptide had been deleted (chimera Del 5). Protein synthesis and pentameric assembly were not altered. In Del 5 transfected cells, pentameric receptors present in the endoplasmic reticulum were not detected on the cell surface where Del 5 proteins appeared as patches. With the Del 5 chimera, export of proteins to the cell surface diminished to about half that of wild-type. We propose that the C-terminal segment plays a double role: (i) through an interaction between the penultimate tyrosine residue of the C-terminal segment and the Cys loop of the N-terminal domain, it locks the receptor in a mature alpha-bungarotoxin binding conformation; (ii) this mature conformation, in turn, masks a retention signal present in the first transmembrane segment allowing properly assembled and matured receptors to escape to the cell surface.


Assuntos
Membrana Celular/metabolismo , Fragmentos de Peptídeos/fisiologia , Receptores 5-HT3 de Serotonina/biossíntese , Receptores 5-HT3 de Serotonina/fisiologia , Sequência de Aminoácidos , Animais , Sítios de Ligação/fisiologia , Membrana Celular/genética , Células LLC-PK1 , Dados de Sequência Molecular , Fragmentos de Peptídeos/biossíntese , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Transporte Proteico/genética , Receptores 5-HT3 de Serotonina/genética , Receptores 5-HT3 de Serotonina/metabolismo , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/fisiologia , Suínos , Transfecção/métodos
20.
Hum Biol ; 76(1): 109-25, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15222683

RESUMO

The excavation of a frozen grave on the Kizil site (dated to be 2500 years old) in the Altai Republic (Central Asia) revealed a skeleton belonging to the Scytho-Siberian population. DNA was extracted from a bone sample and analyzed by autosomal STRs (short tandem repeats) and by sequencing the hypervariable region I (HV1) of the mitochondrial DNA. The resulting STR profile, mitochondrial haplotype, and haplogroup were compared with data from modern Eurasian and northern native American populations and were found only in European populations historically influenced by ancient nomadic tribes of Central Asia.


Assuntos
DNA Mitocondrial/análise , Emigração e Imigração , Antropologia Forense , Genética Populacional , Haplótipos/genética , Sequências de Repetição em Tandem/genética , Ásia , Bases de Dados de Ácidos Nucleicos , Demografia , Fósseis , Marcadores Genéticos , Humanos , Paleontologia , Filogenia , Sibéria , Esqueleto
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