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1.
FASEB J ; 35(12): e22019, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34792819

RESUMO

Exogenously applied mature naïve B220+ /CD19+ /IgM+ /IgD+ B cells are strongly protective in the context of tissue injury. However, the mechanisms by which B cells detect tissue injury and aid repair remain elusive. Here, we show in distinct models of skin and brain injury that MyD88-dependent toll-like receptor (TLR) signaling through TLR2/6 and TLR4 is essential for the protective benefit of B cells in vivo, while B cell-specific deletion of MyD88 abrogated this effect. The B cell response to injury was multi-modal with simultaneous production of both regulatory cytokines, such as IL-10, IL-35, and transforming growth factor beta (TGFß), and inflammatory cytokines, such as tumor necrosis factor alpha (TNFα), IL-6, and interferon gamma. Cytometry analysis showed that this response was time and environment-dependent in vivo, with 20%-30% of applied B cells adopting an immune modulatory phenotype with high co-expression of anti- and pro-inflammatory cytokines after 18-48 h at the injury site. B cell treatment reduced the expression of TNFα and increased IL-10 and TGFß in infiltrating immune cells and fibroblasts at the injury site. Proteomic analysis further showed that B cells have a complex time-dependent homeostatic effect on the injured microenvironment, reducing the expression of inflammation-associated proteins, and increasing proteins associated with proliferation, tissue remodeling, and protection from oxidative stress. These findings chart and validate a first mechanistic understanding of the effects of B cells as an immunomodulatory cell therapy in the context of tissue injury.

2.
J Comput Neurosci ; 49(4): 419-439, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34032982

RESUMO

Intrinsic oscillators in the central nervous system play a preeminent role in the neural control of rhythmic behaviors, yet little is known about how the ionic milieu regulates their output patterns. A powerful system to address this question is the pacemaker nucleus of the weakly electric fish Apteronotus leptorhynchus. A neural network comprised of an average of 87 pacemaker cells and 20 relay cells produces tonic oscillations, with higher frequencies in males compared to females. Previous empirical studies have suggested that this sexual dimorphism develops and is maintained through modulation of buffering of extracellular K+ by a massive meshwork of astrocytes enveloping the pacemaker and relay cells. Here, we constructed a model of this neural network that can generate sustained spontaneous oscillations. Sensitivity analysis revealed the potassium equilibrium potential, EK (as a proxy of extracellular K+ concentration), and corresponding somatic channel conductances as critical determinants of oscillation frequency and amplitude. In models of both the pacemaker nucleus network and isolated pacemaker and relay cells, the frequency increased almost linearly with EK, whereas the amplitude decreased nonlinearly with increasing EK. Our simulations predict that this frequency increase is largely caused by a shift in the minimum K+ conductance over one oscillation period. This minimum is close to zero at more negative EK, converging to the corresponding maximum at less negative EK. This brings the resting membrane potential closer to the threshold potential at which voltage-gated Na+ channels become active, increasing the excitability, and thus the frequency, of pacemaker and relay cells.


Assuntos
Peixe Elétrico , Potássio , Animais , Tronco Encefálico , Feminino , Masculino , Modelos Neurológicos , Caracteres Sexuais
3.
JMIR Public Health Surveill ; 7(4): e24292, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33667173

RESUMO

BACKGROUND: Significant uncertainty has existed about the safety of reopening college and university campuses before the COVID-19 pandemic is better controlled. Moreover, little is known about the effects that on-campus students may have on local higher-risk communities. OBJECTIVE: We aimed to estimate the range of potential community and campus COVID-19 exposures, infections, and mortality under various university reopening plans and uncertainties. METHODS: We developed campus-only, community-only, and campus × community epidemic differential equations and agent-based models, with inputs estimated via published and grey literature, expert opinion, and parameter search algorithms. Campus opening plans (spanning fully open, hybrid, and fully virtual approaches) were identified from websites and publications. Additional student and community exposures, infections, and mortality over 16-week semesters were estimated under each scenario, with 10% trimmed medians, standard deviations, and probability intervals computed to omit extreme outliers. Sensitivity analyses were conducted to inform potential effective interventions. RESULTS: Predicted 16-week campus and additional community exposures, infections, and mortality for the base case with no precautions (or negligible compliance) varied significantly from their medians (4- to 10-fold). Over 5% of on-campus students were infected after a mean of 76 (SD 17) days, with the greatest increase (first inflection point) occurring on average on day 84 (SD 10.2 days) of the semester and with total additional community exposures, infections, and mortality ranging from 1-187, 13-820, and 1-21 per 10,000 residents, respectively. Reopening precautions reduced infections by 24%-26% and mortality by 36%-50% in both populations. Beyond campus and community reproductive numbers, sensitivity analysis indicated no dominant factors that interventions could primarily target to reduce the magnitude and variability in outcomes, suggesting the importance of comprehensive public health measures and surveillance. CONCLUSIONS: Community and campus COVID-19 exposures, infections, and mortality resulting from reopening campuses are highly unpredictable regardless of precautions. Public health implications include the need for effective surveillance and flexible campus operations.


Assuntos
COVID-19/epidemiologia , COVID-19/transmissão , Universidades/organização & administração , COVID-19/mortalidade , Infecções Comunitárias Adquiridas/epidemiologia , Humanos , Modelos Teóricos , Medição de Risco , Incerteza , Estados Unidos/epidemiologia
4.
Trials ; 21(1): 894, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33115527

RESUMO

BACKGROUND: Surgical site infections (SSIs) cause significant patient suffering. Surveillance and feedback of SSI rates is an evidence-based strategy to reduce SSIs, but traditional surveillance methods are slow and prone to bias. The objective of this cluster randomized controlled trial (RCT) is to determine if using optimized statistical process control (SPC) charts for SSI surveillance and feedback lead to a reduction in SSI rates compared to traditional surveillance. METHODS: The Early 2RIS Trial is a prospective, multicenter cluster RCT using a stepped wedge design. The trial will be performed in 29 hospitals in the Duke Infection Control Outreach Network (DICON) and 105 clusters over 4 years, from March 2016 through February 2020; year one represents a baseline period; thereafter, 8-9 clusters will be randomized to intervention every 3 months over a 3-year period using a stepped wedge randomization design. All patients who undergo one of 13 targeted procedures at study hospitals will be included in the analysis; these procedures will be included in one of six clusters: cardiac, orthopedic, gastrointestinal, OB-GYN, vascular, and spinal. All clusters will undergo traditional surveillance for SSIs; once randomized to intervention, clusters will also undergo surveillance and feedback using optimized SPC charts. Feedback on surveillance data will be provided to all clusters, regardless of allocation or type of surveillance. The primary endpoint is the difference in rates of SSI between the SPC intervention compared to traditional surveillance and feedback alone. DISCUSSION: The traditional approach for SSI surveillance and feedback has several major deficiencies because SSIs are rare events. First, traditional statistical methods require aggregation of measurements over time, which delays analysis until enough data accumulate. Second, traditional statistical tests and resulting p values are difficult to interpret. Third, analyses based on average SSI rates during predefined time periods have limited ability to rapidly identify important, real-time trends. Thus, standard analytic methods that compare average SSI rates between arbitrarily designated time intervals may not identify an important SSI rate increase on time unless the "signal" is very strong. Therefore, novel strategies for early identification and investigation of SSI rate increases are needed to decrease SSI rates. While SPC charts are used throughout industry and healthcare to improve and optimize processes, including other types of healthcare-associated infections, they have not been evaluated as a tool for SSI surveillance and feedback in a randomized trial. TRIAL REGISTRATION: ClinicalTrials.gov NCT03075813 , Registered March 9, 2017.


Assuntos
Infecção Hospitalar , Infecção da Ferida Cirúrgica , Infecção Hospitalar/diagnóstico , Infecção Hospitalar/prevenção & controle , Humanos , Controle de Infecções , Medição de Risco , Infecção da Ferida Cirúrgica/diagnóstico , Infecção da Ferida Cirúrgica/prevenção & controle
5.
medRxiv ; 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32908993

RESUMO

BACKGROUND: Significant uncertainty exists in many countries about the safety of, and best strategies for, reopening college and university campuses until the Covid-19 pandemic is better controlled. Little also is known about the effects on-campus students may have on local higher-risk communities. We aimed to estimate potential community and campus Covid-19 exposures, infections, and mortality due to various university reopening and precaution plans under current ranges of assumptions and uncertainties. METHODS: We developed and calibrated campus-only, community-only, and campus-x-community epidemic differential equation and agent-based models. Input parameters for campus and surrounding communities were estimated via published and grey literature, scenario development, expert opinion, accuracy optimization algorithms, and Monte Carlo simulation; models were cross-validated against each other using February-June 2020 data from heterogeneous U.S. counties and states. Campus opening plans (spanning various fully open, hybrid, and fully virtual approaches) were identified from websites and publications. All scenarios were simulated assuming 16-week semesters and estimated ranges for Covid-19 prevalence among community residents and arriving students, precaution compliance, contact frequency, virus attack rates, and tracing and isolation effectiveness. Additional student and community exposures, infections, and mortality were estimated under each scenario, with 10% trimmed medians, standard deviations, and probability intervals computed to omit extreme outlier scenarios. Factorial analyses were conducted to identify intervention inputs with largest and smallest effects. RESULTS: As a base case with no precautions (or no compliance), predicted 16-week student infections and mortality under normal operations ranged significantly from 471 to 9,495 (median: 2,286, SD: 2,627) and 0 to 123 (median: 9, SD: 14) per 10,000 students, respectively. The maximum active exposures across a semester was 15.76% of all students warranting tracing. Total additional community exposures, infections, and mortality ranged from 1 to 187, 13 to 820, and 1 to 21 per 10,000 residents, respectively. 1% and 5% of on-campus students were infected after a mean (SD) of 11 (3) and 76 (17) days, respectively; >10% students infected by the end of a semester in 34.8% of scenarios, with the greatest increase (first inflection point) occurring on aver-age on day 84 (SD: 10.2 days). Common reopening precautions reduced infections by 24% to 26% and mortality by 36% to 50% in both populations. Uncertainties in many factors, however, produced tremendous variability in all results, ranging from medians by -67% to +342%. CONCLUSIONS: Consequences on community and student Covid-19 exposures, infections, and mortality of reopening physical campuses are very highly unpredictable, depending on a combination of random chance, controllable (e.g. physical layouts), and uncontrollable (e.g. human behavior) factors. Implications include needs for criteria to adapt campus operations mid-semester, methods to detect when necessary, and contingency plans for doing so.

7.
BMJ Qual Saf ; 29(6): 472-481, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-31704893

RESUMO

OBJECTIVE: Surgical site infections (SSIs) are common costly hospital-acquired conditions. While statistical process control (SPC) use in healthcare has increased, limited rigorous empirical research compares and optimises these methods for SSI surveillance. We sought to determine which SPC chart types and design parameters maximise the detection of clinically relevant SSI rate increases while minimising false alarms. DESIGN: Systematic retrospective data analysis and empirical optimisation. METHODS: We analysed 12 years of data on 13 surgical procedures from a network of 58 community hospitals. Statistically significant SSI rate increases (signals) at individual hospitals initially were identified using 50 different SPC chart variations (Shewhart or exponentially weighted moving average, 5 baseline periods, 5 baseline types). Blinded epidemiologists evaluated the clinical significance of 2709 representative signals of potential outbreaks (out of 5536 generated), rating them as requiring 'action' or 'no action'. These ratings were used to identify which SPC approaches maximised sensitivity and specificity within a broader set of 3600 individual chart variations (additional baseline variations and chart types, including moving average (MA), and five control limit widths) and over 32 million dual-chart combinations based on different baseline periods, reference data (network-wide vs local hospital SSI rates), control limit widths and other calculation considerations. Results were validated with an additional year of data from the same hospital cohort. RESULTS: The optimal SPC approach to detect clinically important SSI rate increases used two simultaneous MA charts calculated using lagged rolling baseline windows and 1 SD limits. The first chart used 12-month MAs with 18-month baselines and best identified small sustained increases above network-wide SSI rates. The second chart used 6-month MAs with 3-month baselines and best detected large short-term increases above individual hospital SSI rates. This combination outperformed more commonly used charts, with high sensitivity (0.90; positive predictive value=0.56) and practical specificity (0.67; negative predictive value=0.94). CONCLUSIONS: An optimised combination of two MA charts had the best performance for identifying clinically relevant small but sustained above-network SSI rates and large short-term individual hospital increases.


Assuntos
Auditoria Clínica/métodos , Infecção da Ferida Cirúrgica/epidemiologia , Hospitais Comunitários , Humanos , Vigilância em Saúde Pública , Análise de Regressão , Estudos Retrospectivos
8.
Cell Mol Neurobiol ; 40(5): 695-710, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31808010

RESUMO

Cathepsin K deficiency in male mice (Ctsk-/-) results in decreased numbers of hippocampal astrocytes and altered neuronal patterning as well as learning and memory deficits. Additionally, cathepsin K carries essential roles in the thyroid gland where it contributes to the liberation of thyroid hormones (TH). Because TH are essential for brain development, in particular for the cerebellum, we investigated whether cathepsin K's function in the thyroid is directly linked to the brain phenotype of Ctsk-/- mice. Serum levels of thyroid stimulating hormone, brain concentrations of free TH, and deiodinase 2 (Dio2) activity in brain parenchyma as well as cerebellar development were comparable in Ctsk-/- and WT animals, suggesting regular thyroid states and TH metabolism. Despite unaltered transcript levels, protein expression of two TH transporters was enhanced in specific brain regions in Ctsk-/- mice, suggesting altered TH supply to these regions. Thyrotropin releasing hormone (Trh) mRNA levels were enhanced threefold in the hippocampus of Ctsk-/- mice. In the striatum of Ctsk-/- mice the mRNA for Dio2 and hairless were approximately 1.3-fold enhanced, while mRNA levels for monocarboxylate transporter 8 and Trh were reduced to 60% and 40%, respectively, pointing to altered striatal physiology. We conclude that the role of cathepsin K in the thyroid gland is not directly associated with its function in the central nervous system (CNS) of mice. Future studies will show whether the brain region-specific alterations in Trh mRNA may eventually result in altered neuroprotection that could explain the neurobehavioral defects of Ctsk-/- mice.


Assuntos
Catepsina K/fisiologia , Sistema Nervoso Central/enzimologia , Glândula Tireoide/enzimologia , Animais , Catepsina K/genética , Cerebelo/enzimologia , Cerebelo/crescimento & desenvolvimento , Masculino , Camundongos , Camundongos Knockout , RNA Mensageiro/análise , Tireotropina/sangue , Tiroxina/sangue , Tri-Iodotironina/sangue
9.
Infect Control Hosp Epidemiol ; 41(3): 306-312, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31852562

RESUMO

BACKGROUND: The reported incidence of Clostridoides difficile infection (CDI) has increased in recent years, partly due to broadening adoption of nucleic acid amplification tests (NAATs) replacing enzyme immunoassay (EIA) methods. Our aim was to quantify the impact of this switch on reported CDI rates using a large, multihospital, empirical dataset. METHODS: We analyzed 9 years of retrospective CDI data (2009-2017) from 47 hospitals in the southeastern United States; 37 hospitals switched to NAAT during this period, including 24 with sufficient pre- and post-switch data for statistical analyses. Poisson regression was used to quantify the NAAT-over-EIA incidence rate ratio (IRR) at hospital and network levels while controlling for longitudinal trends, the proportion of intensive care unit patient days, changes in surveillance methodology, and previously detected infection cluster periods. We additionally used change-point detection methods to identify shifts in the mean and/or slope of hospital-level CDI rates, and we compared results to recorded switch dates. RESULTS: For hospitals that transitioned to NAAT, average unadjusted CDI rates increased substantially after the test switch from 10.9 to 23.9 per 10,000 patient days. Individual hospital IRRs ranged from 0.75 to 5.47, with a network-wide IRR of 1.75 (95% confidence interval, 1.62-1.89). Reported CDI rates significantly changed 1.6 months on average after switching to NAAT testing (standard deviation, 1.9 months). CONCLUSION: Hospitals that switched from EIA to NAAT testing experienced an average postswitch increase of 75% in reported CDI rates after adjusting for other factors, and this increase was often gradual or delayed.


Assuntos
Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/diagnóstico , Infecções por Clostridium/epidemiologia , Técnicas Imunoenzimáticas/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Hospitais , Humanos , Técnicas de Diagnóstico Molecular/métodos , Vigilância de Evento Sentinela , Sudeste dos Estados Unidos/epidemiologia
10.
Artigo em Inglês | MEDLINE | ID: mdl-31165281

RESUMO

Additive neurogenesis, the net increase in neuronal numbers by addition of new nerve cells to existing tissue, forms the basis for indeterminate spinal cord growth in brown ghost knifefish (Apteronotus leptorhynchus). Among the cells generated through the activity of adult neural stem cells are electromotoneurons, whose axons constitute the electric organ of this weakly electric fish. Electromotoneuron development is organized along a caudo-rostral gradient, with the youngest and smallest of these cells located near the caudal end of the spinal cord. Electromotoneurons start expressing calbindin-D28k when their somata have reached diameters of approximately 10 µm, and they continue expression after they have grown to a final size of about 50 µm. Calbindin-D28k expression is significantly increased in young neurons generated in response to injury. Immunohistochemical staining against caspase-3 revealed that electromotoneurons in both intact and regenerating spinal cord are significantly less likely to undergo apoptosis than the average spinal cord cell. We hypothesize that expression of calbindin-D28k protects electromotoneurons from cell death; and that the evolutionary development of such a neuroprotective mechanism has been driven by the indispensability of electromotoneurons in the fish's electric behavior, and by the high size-dependent costs associated with their production or removal upon cell death.


Assuntos
Calbindina 1/metabolismo , Gimnotiformes/fisiologia , Neurônios Motores/metabolismo , Regeneração Nervosa/fisiologia , Neurogênese/fisiologia , Medula Espinal/metabolismo , Células-Tronco Adultas/metabolismo , Animais , Órgão Elétrico/citologia , Órgão Elétrico/metabolismo , Células-Tronco Neurais/metabolismo
11.
Brain Behav Evol ; 93(1): 4-18, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30982030

RESUMO

The behavioral demands of living in social groups have been linked to the evolution of brain size and structure, but how social organization shapes investment and connectivity within and among functionally specialized brain regions remains unclear. To understand the influence of sociality on brain evolution in ants, a premier clade of eusocial insects, we statistically analyzed patterns of brain region size covariation as a proxy for brain region connectivity. We investigated brain structure covariance in young and old workers of two formicine ants, the Australasian weaver ant Oecophylla smaragdina, a pinnacle of social complexity in insects, and its socially basic sister clade Formica subsericea. As previously identified in other ant species, we predicted that our analysis would recognize in both species an olfaction-related brain module underpinning social information processing in the brain, and a second neuroanatomical cluster involved in nonolfactory sensorimotor processes, thus reflecting conservation of compartmental connectivity. Furthermore, we hypothesized that covariance patterns would reflect divergence in social organization and life histories either within this species pair or compared to other ant species. Contrary to our predictions, our covariance analyses revealed a weakly defined visual, rather than olfactory, sensory processing cluster in both species. This pattern may be linked to the reliance on vision for worker behavioral performance outside of the nest and the correlated expansion of the optic lobes to meet navigational demands in both species. Additionally, we found that colony size and social organization, key measures of social complexity, were only weakly correlated with brain modularity in these formicine ants. Worker age also contributed to variance in brain organization, though in different ways in each species. These findings suggest that brain organization may be shaped by the divergent life histories of the two study species. We compare our findings with patterns of brain organization of other eusocial insects.


Assuntos
Encéfalo/fisiologia , Tamanho do Órgão/fisiologia , Fatores Etários , Animais , Formigas/fisiologia , Comportamento Animal/fisiologia , Evolução Biológica , Cognição/fisiologia , Relações Interpessoais , Olfato , Comportamento Social
12.
J Theor Biol ; 437: 101-114, 2018 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-29031516

RESUMO

The study of indeterminate-growing organisms such as teleost fish presents a unique opportunity for improving our understanding of central nervous tissue growth during adulthood. Integrating the existing experimental data associated with this process into a theoretical framework through mathematical or computational modeling provides further research avenues through sensitivity analysis and optimization. While this type of approach has been used extensively in investigations of tumor growth, wound healing, and bone regeneration, the development of nervous tissue has been rarely studied within a modeling framework. To address this gap, the present work introduces a distributed model of spinal cord growth in the knifefish Apteronotus leptorhynchus, an established teleostean model of adult growth in the central nervous system. The proposed model incorporates two mechanisms, cell proliferation by active stem/progenitor cells and cell drift due to population pressure, both of which are subject to global constraints. A coupled reaction-diffusion equation approach was adopted to represent the densities of actively-proliferating and non-proliferating cells along the longitudinal axis of the spinal cord. Computer simulations using this model yielded biologically-feasible growth trajectories. Subsequent comparisons with whole-organism growth curves allowed the estimation of previously-unknown parameters, such as relative growth rates.


Assuntos
Algoritmos , Gimnotiformes/crescimento & desenvolvimento , Modelos Biológicos , Medula Espinal/crescimento & desenvolvimento , Animais , Proliferação de Células , Simulação por Computador , Gimnotiformes/anatomia & histologia , Medula Espinal/anatomia & histologia , Medula Espinal/citologia , Fatores de Tempo
13.
BMJ Qual Saf ; 27(8): 600-610, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29175853

RESUMO

BACKGROUND: Traditional strategies for surveillance of surgical site infections (SSI) have multiple limitations, including delayed and incomplete outbreak detection. Statistical process control (SPC) methods address these deficiencies by combining longitudinal analysis with graphical presentation of data. METHODS: We performed a pilot study within a large network of community hospitals to evaluate performance of SPC methods for detecting SSI outbreaks. We applied conventional Shewhart and exponentially weighted moving average (EWMA) SPC charts to 10 previously investigated SSI outbreaks that occurred from 2003 to 2013. We compared the results of SPC surveillance to the results of traditional SSI surveillance methods. Then, we analysed the performance of modified SPC charts constructed with different outbreak detection rules, EWMA smoothing factors and baseline SSI rate calculations. RESULTS: Conventional Shewhart and EWMA SPC charts both detected 8 of the 10 SSI outbreaks analysed, in each case prior to the date of traditional detection. Among detected outbreaks, conventional Shewhart chart detection occurred a median of 12 months prior to outbreak onset and 22 months prior to traditional detection. Conventional EWMA chart detection occurred a median of 7months prior to outbreak onset and 14 months prior to traditional detection. Modified Shewhart and EWMA charts additionally detected several outbreaks earlier than conventional SPC charts. Shewhart and SPC charts had low false-positive rates when used to analyse separate control hospital SSI data. CONCLUSIONS: Our findings illustrate the potential usefulness and feasibility of real-time SPC surveillance of SSI to rapidly identify outbreaks and improve patient safety. Further study is needed to optimise SPC chart selection and calculation, statistical outbreak detection rules and the process for reacting to signals of potential outbreaks.


Assuntos
Infecção Hospitalar/epidemiologia , Vigilância em Saúde Pública/métodos , Infecção da Ferida Cirúrgica/epidemiologia , Bases de Dados Factuais , Surtos de Doenças/estatística & dados numéricos , Monitoramento Epidemiológico , Hospitais Comunitários , Humanos , Controle de Infecções , Projetos Piloto , Estudos Retrospectivos , Sudeste dos Estados Unidos/epidemiologia
14.
Wound Repair Regen ; 25(5): 774-791, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28922523

RESUMO

Chronic wounds affect 12-15% of patients with diabetes and are associated with a drastic decrease in their quality of life. Here, we demonstrate that purified mature naive B220+ /CD19+ /IgM+ /IgD+ B cells improve healing of acute and diabetic murine wounds after a single topical application. B cell treatment significantly accelerated acute wound closure by 2-3 days in wild-type mice and 5-6 days in obese diabetic mice. The treatment led to full closure in 43% of chronic diabetic wounds, as compared to only 5% in saline-treated controls. Applying equivalent numbers of T cells or disrupted B cells failed to reproduce these effects, indicating that live B cells mediated pro-healing responses. Topically applied B cell treatment was associated with significantly reduced scar size, increased collagen deposition and maturation, enhanced angiogenesis, and increased nerve growth into and under the healing wound. ß-III tubulin+ nerve endings in scars of wounds treated acutely with B cells showed increased relative expression of growth-associated protein 43. The improved healing associated with B cell treatment was supported by significantly increased fibroblast proliferation and decreased apoptosis in the wound bed and edges, altered kinetics of neutrophil infiltration, as well as an increase in TGF-ß and a significant reduction in MMP2 expression in wound granulation tissue. Our findings indicate that the timeline and efficacy of wound healing can be experimentally manipulated through the direct application of mature, naive B cells, which effectively modify the balance of mature immune cell populations within the wound microenvironment and accelerate the healing process.


Assuntos
Linfócitos B , Terapia Baseada em Transplante de Células e Tecidos/métodos , Diabetes Mellitus Experimental/complicações , Dermatopatias/terapia , Pele/patologia , Cicatrização/imunologia , Doença Aguda , Animais , Biópsia , Sobrevivência Celular , Doença Crônica , Citometria de Fluxo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Pele/imunologia , Dermatopatias/etiologia , Dermatopatias/patologia
15.
Dev Neurobiol ; 77(11): 1269-1307, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28707354

RESUMO

The knifefish Apteronotus leptorhynchus exhibits indeterminate growth throughout adulthood. This phenomenon extends to the spinal cord, presumably through the continuous addition of new neurons and glial cells. However, little is known about the developmental dynamics of cells added during adult growth. The present work characterizes the structural and functional development of the adult spinal cord in this model organism through a comprehensive quantitative analysis of the spatial and temporal dynamics of new cells at various developmental stages. This analysis, based on a novel statistical mapping approach, revealed within the adult spinal cord a wide distribution of both mitotically active and quiescent Sox2-expressing stem/progenitor cells (SPCs). While such cells are particularly concentrated within the ependymal layer near the central canal, the majority of them reside in the parenchyma, resembling the distribution of SPCs observed in the mammalian spinal cord. The active SPCs in the adult knifefish spinal cord give rise to transit amplifying progenitor cells that undergo a few additional mitotic divisions before developing into Hu C/D+ neurons and S100+ glial cells. There is no evidence of long-distance migration of the newborn cells. The persistence of cell proliferation and differentiation, combined with low levels of apoptosis, leads to a continuous addition of cells to the existing tissue. Newly generated neurons have functional and behavioral relevance, as indicated by the integration of axons of new electromotor neurons into the electric organ of these weakly electric fish. This results in a gradual increase in the amplitude of the electric organ discharge during adult development. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1269-1307, 2017.


Assuntos
Diferenciação Celular/fisiologia , Células-Tronco Multipotentes/fisiologia , Neurogênese/fisiologia , Medula Espinal/citologia , Medula Espinal/crescimento & desenvolvimento , Animais , Bromodesoxiuridina/metabolismo , Contagem de Células , Proteínas ELAV/metabolismo , Peixe Elétrico , Órgão Elétrico/citologia , Órgão Elétrico/fisiologia , Feminino , Fluoresceína/metabolismo , Glutamato-Amônia Ligase/metabolismo , Histonas/metabolismo , Masculino , Modelos Anatômicos , Proteínas do Tecido Nervoso/metabolismo , Antígeno Nuclear de Célula em Proliferação/metabolismo , Fatores de Transcrição SOXB1/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo
16.
Artigo em Inglês | MEDLINE | ID: mdl-27225982

RESUMO

Among the cellular processes that follow injury to the central nervous system, glial scar formation is thought to be one of the major factors that prevent regeneration. In regeneration-competent organisms, glial scar formation has been a matter of controversy. We addressed this issue by examining the glial population after spinal cord injury in a model of regeneration competency, the knifefish Apteronotus leptorhynchus. Analysis of spinal cord sections immunostained against the glial markers glial fibrillary acidic protein, vimentin, or chondroitin sulfate proteoglycan failed to produce any evidence for the formation of a glial scar in the area of the lesion at post-injury survival times ranging from 5 to 185 days. This result was independent of the lesion paradigm applied-amputation of the caudal part of the spinal cord or hemisection lesioning-and similar after examination of transverse and longitudinal sections. We hypothesize that the well-developed network of radial glia in both the intact and the injured spinal cord provides a support system for regeneration of tissue lost to injury. This glial network is likely also involved in the generation of new cells, as indicated by the large subset of glial fibrillary acidic protein-labeled glia that express the stem cell marker Sox2.


Assuntos
Gimnotiformes/fisiologia , Neuroglia/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Regeneração da Medula Espinal/fisiologia , Animais , Modelos Animais de Doenças , Proteínas de Peixes/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Gliose , Imuno-Histoquímica , Microscopia Confocal , Microscopia de Fluorescência , Células-Tronco Neurais/patologia , Células-Tronco Neurais/fisiologia , Neuroglia/patologia , Fatores de Transcrição SOXB1/metabolismo , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/patologia
17.
Mol Cell Neurosci ; 68: 9-23, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25827096

RESUMO

Matrix metalloproteinases (MMPs) are a family of highly conserved zinc-dependent proteases involved in both development and pathogenesis. The present study examines the role of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) in adult neurogenesis, using the corpus cerebelli, a subdivision of the cerebellum, of knifefish (Apteronotus leptorhynchus) as a model system. Transcripts of five isoforms of these gelatinases were identified in the central nervous system of this species. Sequence similarity analysis and homology modeling indicated that functionally and structurally critical elements were highly conserved in knifefish gelatinases. Immunohistochemical staining revealed a differential distribution of MMP-2 and MMP-9 at both the cellular and subcellular level. MMP-2 expression was found mainly in Sox2-immunopositive stem/progenitor cells, both quiescent and mitotically active; and was localized in both the cytoplasmic compartment and the nucleus. By contrast, MMP-9 immunoreactivity was absent in neurogenic niches and displayed a more homogenous distribution, with low to moderate intensity levels, in the molecular and granular layers. MMP-9 expression appeared to be restricted to the extracellular space. In situ zymography indicated that gelatinase activity matched the cellular and subcellular distributions of the two MMPs. The observed patterns of gelatinase activity and expression support the hypothesis that MMP-2 is primarily involved in regulation of the activity of stem/progenitor cells that give rise to new granule neurons, whereas MMP-9 facilitates migration of the progeny of these cells by proteolysis of extracellular matrix proteins.


Assuntos
Cerebelo/enzimologia , Metaloproteinase 9 da Matriz/metabolismo , Neurogênese/fisiologia , Células-Tronco Adultas/fisiologia , Animais , Movimento Celular/fisiologia , Cerebelo/citologia , Peixes , Gelatinases/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Metaloproteinase 2 da Matriz/metabolismo , Modelos Moleculares , Antígeno Nuclear de Célula em Proliferação/metabolismo , RNA Mensageiro/metabolismo , Fatores de Transcrição SOXB1/metabolismo , Frações Subcelulares/enzimologia , Vimentina/metabolismo
18.
Brain Behav Evol ; 85(1): 63-76, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25766867

RESUMO

A central question in brain evolution concerns how selection has structured neuromorphological variation to generate adaptive behavior. In social insects, brain structures differ between reproductive and sterile castes, and worker behavioral specializations related to morphology, age, and ecology are associated with intra- and interspecific variation in investment in functionally different brain compartments. Workers in the hyperdiverse ant genus Pheidole are morphologically and behaviorally differentiated into minor and major subcastes that exhibit distinct species-typical patterns of brain compartment size variation. We examined integration and modularity in brain organization and its developmental patterning in three ecotypical Pheidole species by analyzing intra- and interspecific morphological and neuroanatomical covariation. Our results identified two trait clusters, the first involving olfaction and social information processing and the second composed of brain regions regulating nonolfactory sensorimotor functions. Patterns of size covariation between brain compartments within subcastes were consistent with levels of behavioral differentiation between minor and major workers. Globally, brains of mature workers were more heterogeneous than brains of newly eclosed workers, suggesting diversified developmental trajectories underscore species- and subcaste-typical brain organization. Variation in brain structure associated with the striking worker polyphenism in our sample of Pheidole appears to originate from initially differentiated brain templates that further diverge through species- and subcaste-specific processes of maturation and behavioral development.


Assuntos
Formigas/anatomia & histologia , Formigas/fisiologia , Envelhecimento , Animais , Comportamento Animal , Evolução Biológica , Encéfalo/anatomia & histologia , Encéfalo/crescimento & desenvolvimento , Especificidade da Espécie
19.
Dev Neurobiol ; 75(1): 39-65, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25044932

RESUMO

Adult neurogenesis has been described in dozens of brain regions in teleost fish, with the largest number of new neurons being generated in the cerebellum. Here, we characterized the cerebellar neural stem/progenitor cells (NSPCs) in the brown ghost knifefish (Apteronotus leptorhynchus), an established model system of adult neurogenesis. The majority of the new cerebellar cells arise from neurogenic niches located medially, at the interface of the dorsal/ventral molecular layers and the granular layer. NSPCs within these niches give rise to transit-amplifying progenitors which populate the molecular layer, where they continue to proliferate during their migration toward target areas in the granular layer. At any given time, the majority of proliferating cells are located in the molecular layer. Immunohistochemical staining revealed that the stem cell markers Sox2, Meis1/2/3, Islet1, and, to a lesser extent, Pax6, are widely expressed in all regions of the adult cerebellum. A large subpopulation of these NSPCs coexpress S100, GFAP, and/or vimentin, indicating astrocytic identity. This is further supported by the specific effect of the gliotoxin l-methionine sulfoximine, which leads to a targeted decrease in the number of GFAP+ cells that coexpress Sox2 or the proliferation marker PCNA. Pulse-chase analysis of the label size associated with new cells after administration of 5-bromo-2'-deoxyuridine demonstrated that, on average, two additional cell divisions occur after completion of the initial mitotic cycle. Overall numbers of NSPCs in the cerebellum niches increase consistently over time, presumably in parallel with the continuous growth of the brain.


Assuntos
Células-Tronco Adultas/fisiologia , Cerebelo/fisiologia , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Células-Tronco Adultas/citologia , Animais , Cerebelo/citologia , Peixes , Células-Tronco Neurais/citologia
20.
Dev Neurobiol ; 74(9): 934-52, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24639054

RESUMO

Neural stem/progenitor cells in the neurogenic niches of the adult brain are widely assumed to give rise predominantly to neurons, rather than glia. Here, we performed a quantitative analysis of the resident neural progenitors and their progeny in the adult pacemaker nucleus (Pn) of the weakly electric fish Apteronotus leptorhynchus. Approximately 15% of all cells in this brainstem nucleus are radial glia-like neural stem/progenitor cells. They are distributed uniformly within the tissue and are characterized by the expression of Sox2 and Meis 1/2/3. Approximately 2-3% of them are mitotically active, as indicated by expression of proliferating cell nuclear antigen. Labeling of proliferating cells with a single pulse of BrdU, followed by chases of up to 100 days, revealed that new cells are generated uniformly throughout the nucleus and do not undergo substantial migration. New cells differentiate into S100+ astrocytes and Hu C/D+ small interneurons at a ratio of 4:1, reflecting the proportions of the total glia and neurons in this brain region. The continuous addition of new cells leads to a diffuse growth of the Pn, which doubles in volume and total cell number over the first 2 years following sexual maturation of the fish. However, the number of pacemaker and relay cells, which constitute the oscillatory neural network, remains constant throughout adult life. We hypothesize that the dominance of gliogenesis is an adaptation to the high-frequency firing of the oscillatory neurons in this nucleus.


Assuntos
Astrócitos/fisiologia , Relógios Biológicos/fisiologia , Tronco Encefálico/fisiologia , Gimnotiformes/fisiologia , Interneurônios/fisiologia , Neurogênese/fisiologia , Animais , Astrócitos/citologia , Tronco Encefálico/anatomia & histologia , Tronco Encefálico/crescimento & desenvolvimento , Contagem de Células , Simulação por Computador , Feminino , Gimnotiformes/anatomia & histologia , Gimnotiformes/crescimento & desenvolvimento , Interneurônios/citologia , Masculino , Modelos Biológicos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/fisiologia , Tamanho do Órgão , Maturidade Sexual
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