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1.
Nat Commun ; 13(1): 4205, 2022 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-35864084

RESUMO

Clouds regulate the Greenland Ice Sheet's surface energy balance through the competing effects of shortwave radiation shading and longwave radiation trapping. However, the relative importance of these effects within Greenland's narrow ablation zone, where nearly all meltwater runoff is produced, remains poorly quantified. Here we use machine learning to merge MODIS, CloudSat, and CALIPSO satellite observations to produce a high-resolution cloud radiative effect product. For the period 2003-2020, we find that a 1% change in cloudiness has little effect (±0.16 W m-2) on summer net radiative fluxes in the ablation zone because the warming and cooling effects of clouds compensate. However, by 2100 (SSP5-8.5 scenario), radiative fluxes in the ablation zone will become more than twice as sensitive (±0.39 W m-2) to changes in cloudiness due to reduced surface albedo. Accurate representation of clouds will therefore become increasingly important for forecasting the Greenland Ice Sheet's contribution to global sea-level rise.

2.
Clin Radiol ; 76(10): 748-762, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33579518

RESUMO

The incidence of gastrointestinal (GI) malignancy is increasing worldwide. In particular, there is a concerning rise in incidence of GI cancer in younger adults. Direct endoscopic visualisation of luminal tumour sites requires invasive procedures, which are associated with certain risks, but remain necessary because of limitations in current imaging techniques and the continuing need to obtain tissue for diagnosis and genetic analysis; however, management of GI cancer is increasingly reliant on non-invasive, radiological imaging to diagnose, stage, and treat these malignancies. Oesophageal, gastric, and colorectal malignancies require specialist investigation and treatment due to the complex nature of the anatomy, biology, and subsequent treatment strategies. As cancer imaging techniques develop, many opportunities to improve tumour detection, diagnostic accuracy and treatment monitoring present themselves. This review article aims to report current imaging practice, advances in various radiological modalities in relation to GI luminal tumour sites and describes opportunities for GI radiologists to improve patient outcomes.


Assuntos
Neoplasias Colorretais/diagnóstico por imagem , Diagnóstico por Imagem/métodos , Neoplasias Esofágicas/diagnóstico por imagem , Neoplasias Gástricas/diagnóstico por imagem , Humanos
4.
J Affect Disord ; 264: 193-200, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32056750

RESUMO

BACKGROUND: Postpartum depression (PPD) is a common and gravely disabling health concern. Repetitive transcranial magnetic stimulation (rTMS) is an FDA approved treatment for major depression and may be a valuable tool in the treatment of PPD. The treatment effect of rTMS is rapid, generally well tolerated, without systemic effects, and without medication exposure to a fetus and/or breastfed infant. METHODS: Six women with PPD received 20 sessions of 10 Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) over a 4 week period. Psychiatric rating scales (BDI, EPDS, STATI), cognitive assessments (MMSE, Trails B, List Generation) and breastfeeding practices were surveyed at baseline and post rTMS treatment. BDI and EPDS were obtained weekly, as well as 3 months and 6 months post study conclusion. RESULTS: Average BDI, EPDS, and STAI scores declined over the 4-week duration of rTMS treatment. Of the six patients, four achieved remission as assessed by EPDS and one achieved remission and two responded as assessed by BDI. Mean BDI and EPDS scores at 3 and 6 months follow-up remained below levels at study entry. No evidence of cognitive changes or breastfeeding disruptions. LIMITATIONS: This was an exploratory study with small sample size with no sham control arm. Daily administration of rTMS provides potential for confounding of behavioral activation in the otherwise often isolative postpartum period. CONCLUSIONS: rTMS was safe and well tolerated among participants with evidence of sustained improvements in depression and anxiety scores. This study supports rTMS as a promising non-pharmacologic treatment modality for perinatal depression.


Assuntos
Depressão Pós-Parto , Transtorno Depressivo Maior , Depressão Pós-Parto/terapia , Transtorno Depressivo Maior/terapia , Feminino , Humanos , Córtex Pré-Frontal , Gravidez , Estimulação Magnética Transcraniana , Resultado do Tratamento
5.
Mol Psychiatry ; 23(5): 1345-1355, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-28373690

RESUMO

Dietary intake of methyl donors, such as folic acid and methionine, shows considerable intra-individual variation in human populations. While it is recognized that maternal departures from the optimum of dietary methyl donor intake can increase the risk for mental health issues and neurological disorders in offspring, it has not been explored whether paternal dietary methyl donor intake influences behavioral and cognitive functions in the next generation. Here, we report that elevated paternal dietary methyl donor intake in a mouse model, transiently applied prior to mating, resulted in offspring animals (methyl donor-rich diet (MD) F1 mice) with deficits in hippocampus-dependent learning and memory, impaired hippocampal synaptic plasticity and reduced hippocampal theta oscillations. Gene expression analyses revealed altered expression of the methionine adenosyltransferase Mat2a and BK channel subunit Kcnmb2, which was associated with changes in Kcnmb2 promoter methylation in MD F1 mice. Hippocampal overexpression of Kcnmb2 in MD F1 mice ameliorated altered spatial learning and memory, supporting a role of this BK channel subunit in the MD F1 behavioral phenotype. Behavioral and gene expression changes did not extend into the F2 offspring generation. Together, our data indicate that paternal dietary factors influence cognitive and neural functions in the offspring generation.


Assuntos
Cognição/fisiologia , Suplementos Nutricionais/efeitos adversos , Herança Paterna/fisiologia , Animais , Metilação de DNA , Dieta , Epigênese Genética , Pai , Ácido Fólico/metabolismo , Hipocampo/metabolismo , Subunidades beta do Canal de Potássio Ativado por Cálcio de Condutância Alta , Aprendizagem/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Metionina/metabolismo , Metionina Adenosiltransferase , Metilação , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Herança Paterna/genética , Regiões Promotoras Genéticas
7.
Oncogenesis ; 6(9): e378, 2017 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-28920928

RESUMO

Adhesion to extracellular matrix (ECM) is crucially important for survival of normal epithelial cells as detachment from ECM triggers specific apoptosis known as anoikis. As tumor cells lose the requirement for anchorage to ECM, they rely on cell-cell adhesion 'multicellular aggregation' for survival. Multicellular aggregation of tumor cells also significantly determines the sensitivity of tumor cells to the cytotoxic effects of chemotherapeutics. In this report, we demonstrate that expression of immunoglobulin containing and proline-rich receptor-1 (IGPR-1) is upregulated in human primary colon cancer. Our study demonstrates that IGPR-1 promotes tumor multicellular aggregation, and interfering with its adhesive function inhibits multicellular aggregation and, increases cell death. IGPR-1 supports colon carcinoma tumor xenograft growth in mouse, and inhibiting its activity by shRNA or blocking antibody inhibits tumor growth. More importantly, IGPR-1 regulates sensitivity of tumor cells to the chemotherapeutic agent, doxorubicin/adriamycin by a mechanism that involves doxorubicin-induced AKT activation and phosphorylation of IGPR-1 at Ser220. Our findings offer novel insight into IGPR-1's role in colorectal tumor growth, tumor chemosensitivity, and as a possible novel anti-cancer target.

8.
Neuroimage Clin ; 15: 194-199, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28529875

RESUMO

BACKGROUND/AIM: The safety of amateur and professional boxing is a contentious issue. We hypothesised that advanced magnetic resonance imaging and neuropsychological testing could provide evidence of acute and early brain injury in amateur boxers. METHODS: We recruited 30 participants from a university amateur boxing club in a prospective cohort study. Magnetic resonance imaging (MRI) and neuropsychological testing was performed at three time points: prior to starting training; within 48 h following a first major competition to detect acute brain injury; and one year follow-up. A single MRI acquisition was made from control participants. Imaging analysis included cortical thickness measurements with Advanced Normalization Tools (ANTS) and FreeSurfer, voxel based morphometry (VBM), and Tract Based Spatial Statistics (TBSS). A computerized battery of neuropsychological tests was performed assessing attention, learning, memory and impulsivity. RESULTS: During the study period, one boxer developed seizures controlled with medication while another developed a chronic subdural hematoma requiring neurosurgical drainage. A total of 10 boxers contributed data at to the longitudinal assessment protocol. Reasons for withdrawal were: logistics (10), stopping boxing (7), withdrawal of consent (2), and development of a chronic subdural hematoma (1). No significant changes were detected using VBM, TBSS, cortical thickness measured with FreeSurfer or ANTS, either cross-sectionally at baseline, or longitudinally. Neuropsychological assessment of boxers found attention/concentration improved over time while planning and problem solving ability latency decreased after a bout but recovered after one year. CONCLUSION: While this neuroimaging and neuropsychological assessment protocol could not detect any evidence of brain injury, one boxer developed seizures and another developed a chronic sub-dural haematoma.


Assuntos
Traumatismos em Atletas/diagnóstico , Boxe/fisiologia , Lesões Encefálicas/diagnóstico , Imageamento por Ressonância Magnética/métodos , Testes Neuropsicológicos , Adulto , Traumatismos em Atletas/patologia , Traumatismos em Atletas/fisiopatologia , Lesões Encefálicas/etiologia , Lesões Encefálicas/patologia , Lesões Encefálicas/fisiopatologia , Feminino , Humanos , Masculino , Estudos Prospectivos , Universidades , Adulto Jovem
9.
Malays J Pathol ; 38(2): 165-8, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27568675

RESUMO

Prostate cancer is one of the most common cancers among men worldwide and in the USA. Most prostate cancer progression either locally invades to seminal vesicles or metastasizes distally to bone. Skin is not a common site of metastasis for the majority of malignancies including prostate cancer. This paper reports two extremely rare cases of prostate carcinoma metastatic to the skin: a 74-year-old man previously treated with radiation for prostate cancer with cutaneous metastases to the shoulder and a 68-year-old man with prostate adenocarcinoma and cutaneous metastases to the groin. Both patients were diagnosed with skin punch biopsy and later confirmed with immunohistochemical staining for PSA and prostate specific acid phosphatase, specific for prostatic carcinoma. Although unusual, development of multiple skin lesions in patients with prostate adenocarcinoma should raise the flags of cutaneous metastases.


Assuntos
Adenocarcinoma/secundário , Neoplasias da Próstata/patologia , Neoplasias Cutâneas/secundário , Idoso , Biomarcadores Tumorais/análise , Humanos , Imuno-Histoquímica , Masculino
10.
Psychoneuroendocrinology ; 55: 164-72, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25768266

RESUMO

BACKGROUND: Lactation is thought to buffer stress reactivity via oxytocin (OT). Dysregulation of the HPA axis has been reported in women with postpartum depression (PPD). The co-occurrence of PPD and lactation failure suggests that abnormalities in OT signaling may play a role in PPD. We hypothesized that abnormal OT signaling is implicated in dysregulated HPA axis reactivity among postpartum women with mood symptoms. In a prospective perinatal cohort, we tested associations between OT levels during breastfeeding and stress reactivity. METHODS: We recruited 52 pregnant women who intended to breastfeed, among whom 47 underwent a standardized stressor, the Trier Social Stress Test (TSST), at 8 weeks postpartum. 39 were breastfeeding at time of TSST. We assessed mood symptoms using validated instruments and defined as symptomatic women with EPDS ≥ 10 and/or Spielberger ≥ 34. Following IV placement for blood draws, women breastfed their infants and then underwent the TSST. Mothers' hormone responses were quantified. RESULTS: Among symptomatic breastfeeding women (N=11; asymptomatic N=28), we found lower OT levels during breastfeeding (p<0.05) and higher CORT levels (p<0.05) both during breastfeeding and the TSST, as compared to asymptomatic breastfeeding women. In a mixed effects model examining CORT reactivity by symptom group and OT AUC, we observed a paradoxical response in symptomatic breastfeeding women during the TSST (group × time × OT AUC p<0.05); higher OT AUC was associated with higher CORT. CONCLUSIONS: In all breastfeeding women, the surge of OT during feeding appears to buffer subsequent stress-induced CORT secretion. However, in symptomatic breastfeeding women, we found a positive correlation between OT AUC and CORT, instead of the expected negative correlation, which we found among asymptomatic women.


Assuntos
Aleitamento Materno , Depressão Pós-Parto/metabolismo , Hidrocortisona/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Lactação/metabolismo , Ocitocina/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Estresse Psicológico/metabolismo , Adulto , Ansiedade/metabolismo , Ansiedade/psicologia , Estudos de Casos e Controles , Estudos de Coortes , Depressão/metabolismo , Depressão Pós-Parto/psicologia , Feminino , Humanos , Lactação/psicologia , Estudos Longitudinais , Período Pós-Parto , Estudos Prospectivos , Estresse Psicológico/psicologia , Adulto Jovem
11.
Cogn Neurosci ; 4(1): 12-20, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23486527

RESUMO

A prevalent view of working memory (WM) considers it to be capacity-limited, fixed to a set number of items. However, recent shared resource models of WM have challenged this "quantized" account using measures of recall precision. Although this conceptual framework can account for several features of visual WM, it remains to be established whether it also applies to auditory WM. We used a novel pitch-matching paradigm to probe participants' memory of pure tones in sequences of varying length, and measured their precision of recall. Crucially, this provides an index of the variability of memory representation around its true value, rather than a binary "yes/no" recall measure typically used in change detection paradigms. We show that precision of auditory WM varies with both memory load and serial order. Moreover, auditory WM resources can be prioritized to cued items, improving precision of recall, but with a concomitant cost to other items, consistent with a resource model account.


Assuntos
Estimulação Acústica/métodos , Memória de Curto Prazo/fisiologia , Rememoração Mental/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Modelos Estatísticos , Percepção da Altura Sonora/fisiologia , Adulto Jovem
12.
Behav Genet ; 42(2): 299-312, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21909962

RESUMO

Mouse models of Rett syndrome, with targeted mutations in the Mecp2 gene, show a high degree of phenotypic consistency with the clinical syndrome. In addition to severe and age-specific regression in motor and cognitive abilities, a variety of studies have demonstrated that Mecp2 mutant mice display impaired social behavior. Conversely, other studies indicate complex enhancements of social behavior in Mecp2 mutant mice. Since social behavior is a complicated accumulation of constructs, we performed a series of classic and refined social behavior tasks and revealed a relatively consistent pattern of enhanced pro-social behavior in hypomorphic Mecp2 (308/Y) mutant mice. Analyses of repetitive motor acts, and cognitive stereotypy did not reveal any profound differences due to genotype. Taken together, these results suggest that the mutations associated with Rett syndrome are not necessarily associated with autism-relevant social impairment in mice. However, this gene may be a valuable candidate for revealing basic mechanisms of affiliative behavior.


Assuntos
Proteína 2 de Ligação a Metil-CpG/genética , Síndrome de Rett/psicologia , Transtornos do Comportamento Social/psicologia , Comportamento Social , Animais , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Síndrome de Rett/genética , Transtornos do Comportamento Social/genética
13.
Exp Brain Res ; 209(4): 587-98, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21336830

RESUMO

Response time, or latency, is increasingly being used to provide information about neural decision processes. LATER (Linear Approach to Threshold with Ergodic Rate) is a quasi-Bayesian model of decision-making, with the additional feature that it introduces a degree of gratuitous randomisation into the decision process. It has had some success in predicting latencies under various conditions, but has not specifically been applied to an equally important aspect of decision-making, namely errors: a complete model of decision-making should not only account for latency distributions of correct decisions but also of wrong ones. We therefore used a decision task that generates large numbers of errors: subjects are told to look at suddenly appearing targets of one colour, but not another. We found that subjects' faster responses are as likely to be correct as wrong, but eventually the latency distributions diverge, with errors becoming infrequent. It seems that colour information, arriving after a delay, results both in cancellation of the developing response to the mere existence of the target and in delayed initiation of the correct response. A simple model, using LATER units in a similar way to one that has previously successfully modelled countermanding, accurately predicts latency distributions and proportions of all responses, whether correct or incorrect, demonstrating that the LATER model can indeed account for errors as well as correct responses.


Assuntos
Tomada de Decisões/fisiologia , Tempo de Reação/fisiologia , Movimentos Sacádicos/fisiologia , Feminino , Humanos , Masculino , Modelos Psicológicos , Testes Neuropsicológicos , Estimulação Luminosa , Desempenho Psicomotor/fisiologia
14.
Genes Brain Behav ; 10(2): 228-35, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21040460

RESUMO

The BTBR T+tf/J inbred mouse strain displays a variety of persistent phenotypic alterations similar to those exhibited in autism spectrum disorders (ASDs). The unique genetic background of the BTBR strain is thought to underlie its lack of reciprocal social interactions, elevated repetitive self-directed grooming, and restricted exploratory behaviors. In order to clarify the existence, range, and mechanisms of abnormal repetitive behaviors within BTBR mice, we performed detailed analyses of the microstructure of self-grooming patterns and noted increased overall grooming, higher percentages of interruptions in grooming bouts and a concomitant decrease in the proportion of incorrect sequence transitions compared to C57BL/6J inbred mice. Analyses of active phase home-cage behavior also revealed an increase in stereotypic bar-biting behavior in the BTBR strain relative to B6 mice. Finally, in a novel object investigation task, the BTBR mice exhibited greater baseline preference for specific unfamiliar objects as well as more patterned sequences of sequential investigations of those items. These results suggest that the repetitive, stereotyped behavior patterns of BTBR mice are relatively pervasive and reflect both motor and cognitive mechanisms. Furthermore, other pre-clinical mouse models of ASDs may benefit from these more detailed analyses of stereotypic behavior.


Assuntos
Transtorno Autístico/genética , Transtorno Autístico/psicologia , Cognição/fisiologia , Atividade Motora/fisiologia , Transtorno de Movimento Estereotipado/genética , Transtorno de Movimento Estereotipado/psicologia , Animais , Modelos Animais de Doenças , Comportamento Exploratório/fisiologia , Asseio Animal , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes Neurológicos , Gravação em Vídeo
16.
Chaos ; 19(3): 033140, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19792020

RESUMO

A premixed flat flame on a circular porous plug burner can form patterns of one or two concentric rings of cells in which brighter, hotter regions are separated by darker, cooler cusps and folds. Dynamic states are found at parameter values that are interleaved between those of the ordered states. Rotating states, modulated rotating states, hopping states, and intermittently ordered states have all been observed with motions of approximately 100 degrees/s. These states have been described using the ideas of dynamical systems. Their characteristics have been analyzed using modal decomposition techniques. Ratcheting states are qualitatively and quantitatively different from these other dynamic states. In ratcheting states one or both of the concentric rings rotate very slowly, approximately 0.8 degrees/s, each speeding up and slowing down in a manner unique to that state. Measurements of the angular displacement and computed values of the angular velocity are presented for four ratcheting states. The experimental results are discussed in the context of the physical characteristics of the flame front and in terms of bifurcations of systems with symmetry. Many of the principal features of ratcheting motion are not yet understood.


Assuntos
Algoritmos , Simulação por Computador , Calefação , Modelos Estatísticos , Dinâmica não Linear , Oscilometria/métodos
17.
Genome Dyn ; 6: 91-109, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19696496

RESUMO

The thermophilic Campylobacter species C. jejuni and C. coli are important human pathogens, which are major causes of bacterial gastroenteritis. The recent progress in genomics techniques has allowed for a rapid increase in our knowledge of the molecular biology of Campylobacter species, but needs to be matched by concurrent increases in our understanding of the unique biology of these organisms. Campylobacter species display significant levels of genomic variation via natural transformation, phase variation, plasmid transfer and infection with bacteriophages, and this poses a continuous challenge for studies on pathogenesis, physiology, epidemiology and evolution of Campylobacter. In this chapter we will review the current state of the art of the genomics of thermophilic Campylobacter species, and opportunities where genomics can further contribute to our understanding of the biology of these successful human pathogens.


Assuntos
Campylobacter jejuni , Campylobacter , Bacteriófagos/genética , Campylobacter/genética , Campylobacter jejuni/genética , Evolução Molecular , Genômica , Humanos , Dados de Sequência Molecular , Plasmídeos
18.
Mol Psychiatry ; 13(9): 858-72, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18332879

RESUMO

The glutamate receptor 6 (GluR6 or GRIK2, one of the kainate receptors) gene resides in a genetic linkage region (6q21) associated with bipolar disorder (BPD), but its function in affective regulation is unknown. Compared with wild-type (WT) and GluR5 knockout (KO) mice, GluR6 KO mice were more active in multiple tests and super responsive to amphetamine. In a battery of specific tests, GluR6 KO mice also exhibited less anxious or more risk-taking type behavior and less despair-type manifestations, and they also had more aggressive displays. Chronic treatment with lithium, a classic antimanic mood stabilizer, reduced hyperactivity, aggressive displays and some risk-taking type behavior in GluR6 KO mice. Hippocampal and prefrontal cortical membrane levels of GluR5 and KA-2 receptors were decreased in GluR6 KO mice, and chronic lithium treatment did not affect these decreases. The membrane levels of other glutamatergic receptors were not significantly altered by GluR6 ablation or chronic lithium treatment. Together, these biochemical and behavioral results suggest a unique role for GluR6 in controlling abnormalities related to the behavioral symptoms of mania, such as hyperactivity or psychomotor agitation, aggressiveness, driven or increased goal-directed pursuits, risk taking and supersensitivity to psychostimulants. Whether GluR6 perturbation is involved in the mood elevation or thought disturbance of mania and the cyclicity of BPD are unknown. The molecular mechanism underlying the behavioral effects of lithium in GluR6 KO mice remains to be elucidated.


Assuntos
Transtorno Bipolar/metabolismo , Receptores de Ácido Caínico/metabolismo , Análise de Variância , Animais , Antimaníacos/uso terapêutico , Aprendizagem da Esquiva/efeitos dos fármacos , Sintomas Comportamentais , Transtorno Bipolar/tratamento farmacológico , Transtorno Bipolar/genética , Transtorno Bipolar/fisiopatologia , Comportamento Exploratório/efeitos dos fármacos , Relações Interpessoais , Carbonato de Lítio/uso terapêutico , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Ácido Caínico/deficiência , Assunção de Riscos , Natação , Fatores de Tempo , Receptor de GluK2 Cainato
19.
Artigo em Inglês | MEDLINE | ID: mdl-19150962

RESUMO

All multicellular organisms have requirements for tumor suppression to regulate cellular proliferation during either embryonic development or adult life. However, different organisms have vastly different requirements. Adult tumor suppression is probably not crucial to organisms possessing both short life spans and largely postmitotic soma. In contrast, animals with lifelong tissue turnover or those capable of regenerating body parts lost to injury must possess evolutionarily selected mechanisms to control rates of cell proliferation such that tissue homeostasis can be maintained or restored after injury. We hypothesize that these biological differences may help to explain why the lists of tumor suppressor genes in humans and Drosophila are largely nonoverlapping. Here, we address this disparity by examining the tumor suppressor gene content of two outgroups to the vertebrates and flies/nematodes: the freshwater planarian and the single-celled choanoflagellate. Both of these organisms have recently had their genomes sequenced, giving us a first glimpse of which known tumor suppressor genes have been maintained during evolution. In addition, we attempt to resolve which genes may have had ancestral tumor suppressor function and which may have acquired this function de novo.


Assuntos
Neoplasias/prevenção & controle , Regeneração/fisiologia , Células-Tronco/fisiologia , Células-Tronco Adultas/citologia , Células-Tronco Adultas/fisiologia , Animais , Evolução Biológica , Proliferação de Células , Drosophila , Eucariotos , Genes Supressores de Tumor , Humanos , Longevidade , Neoplasias/genética , Neoplasias/patologia , Planárias , Regeneração/genética , Células-Tronco/citologia , Vertebrados
20.
J Electromyogr Kinesiol ; 18(5): 807-14, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17449278

RESUMO

Spine motion has been described to have two regions, a neutral zone where lumbar rotation can occur with little resistance and an elastic zone where structures such as ligaments, facet joints and intervertebral disks resist rotation. In vivo, the passive musculature can contribute to further limiting the functional neutral range of lumbar motion. Movement out of this functional neutral range could potentially put greater loads on these structures. In this study, the range of lumbar curvature rotation was examined in twelve healthy, untrained volunteers at four torso inclination angles. The lumbar curvature during straight-leg lifting tasks was then defined as a percentage of this range of possible lumbar curvatures. Subjects were found to remain neutrally oriented during the flexion phase of a lifting task. During the extension phase of the lifting task, however, subjects were found to assume a more kyphotic posture, approaching the edge of the functional range of motion. This was found to be most pronounced for heavy lifting tasks. By allowing the lumbar curvature to go into a highly kyphotic posture, subjects may be taking advantage of stretch-shortening behavior in extensor musculature and associated tendons to reduce the energy required to raise the torso. Such a kyphotic posture during extension, however, may put excessive loading on the elastic structures of the spine and torso musculature increasing the risk of injury.


Assuntos
Remoção , Vértebras Lombares/fisiologia , Movimento/fisiologia , Pelve/fisiologia , Equilíbrio Postural/fisiologia , Amplitude de Movimento Articular/fisiologia , Análise e Desempenho de Tarefas , Suporte de Carga/fisiologia , Adulto , Feminino , Humanos , Masculino
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