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1.
Sci Total Environ ; 871: 161981, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-36739015

RESUMO

Sedimentomics methods offer insight into the physiological parameters that influence freshwater sediment organic matter (sedOM). To date, most sedimentomics studies characterized variations across large spatial and environmental gradients; here we examine whether sedimentomics methods capture subtle sedOM variations within a relatively homogeneous study area in southwestern Nova Scotia, Canada. Additionally, we explore the lake sedimentome for candidate biomarkers related to ongoing carnivorous animal farming in the region. Sediment cores were recovered from seven lakes across a trophic (oligo- to eu- trophic) and anthropogenic land use gradient (carnivorous animal farming in catchment, downstream of farming, no farming nearby). Subsamples that dated prior to 1910 (pre-carnivorous animal farming) and later than 2010 (during carnivorous animal farming) were analyzed using UHPLC-HRMS in both negative (ESI-) and positive (ESI+) electrospray ionization modes. Cluster analysis (k-means) showed replicate samples from a given lake clustered distinctly from one another in both ESI modes, indicating sedOM captured subtle variations between lake systems. PCA combined with multiple linear regression indicated carnivorous animal farming and OM source explained most of the observed variation in lake sedOM. Principal component analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) of ESI- and ESI+ data sets identified 103 unique candidate biomarkers. Ten strong candidate biomarkers were identified using graphical methods; more research is required for biomarker verification and molecular characterization. Our results indicate sedimentomics could be used in environmentally homogeneous areas, offering insight into the controls of sedOM cycling. Additionally, we identified prospective biomarkers related to carnivorous animal farming that could be used to understand relative contributions of farming to ongoing eutrophication issues in southwestern Nova Scotia.


Assuntos
Biomarcadores Ambientais , Monitoramento Ambiental , Animais , Lagos , Agricultura , Nova Escócia , Sedimentos Geológicos/análise
2.
Neuropathol Appl Neurobiol ; 47(2): 316-327, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32910464

RESUMO

AIMS: Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a life-threatening condition often associated with highly raised serum antibodies to glycine receptors (GlyRs); these bind to the surface of large neurons and interneurons in rodent brain and spinal cord sections and, in vitro, inhibit function and reduce surface expression of the GlyRs. The effects in vivo have not been reported. METHODS: Purified plasma IgG from a GlyR antibody-positive patient with PERM, and a healthy control (HC), was injected daily into the peritoneal cavity of mice for 12 days; lipopolysaccharide (LPS) to open the blood-brain barrier, was injected on days 3 and 8. Based on preliminary data, behavioural tests were only performed 48 h post-LPS on days 5-7 and 10-12. RESULTS: The GlyR IgG injected mice showed impaired ability on the rotarod from days 5 to 10 but this normalized by day 12. There were no other behavioural differences but, at termination (d13), the GlyR IgG-injected mice had IgG deposits on the neurons that express GlyRs in the brainstem and spinal cord. The IgG was not only on the surface but also inside these large GlyR expressing neurons, which continued to express surface GlyR. CONCLUSIONS: Despite the partial clinical phenotype, not uncommon in passive transfer studies, the results suggest that the antibodies had accessed the GlyRs in relevant brain regions, led to antibody-mediated internalization and increased GlyR synthesis, compatible with the temporary loss of function.


Assuntos
Autoanticorpos/farmacologia , Encefalomielite/imunologia , Imunoglobulina G/farmacologia , Neurônios Motores/metabolismo , Rigidez Muscular/imunologia , Receptores de Glicina/metabolismo , Animais , Autoanticorpos/imunologia , Autoantígenos/imunologia , Autoantígenos/metabolismo , Tronco Encefálico/imunologia , Tronco Encefálico/metabolismo , Encefalomielite/metabolismo , Humanos , Imunoglobulina G/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios Motores/imunologia , Rigidez Muscular/metabolismo , Mioclonia/imunologia , Mioclonia/metabolismo , Receptores de Glicina/imunologia , Medula Espinal/imunologia , Medula Espinal/metabolismo
3.
Curr Biol ; 30(3): 465-479.e5, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-31956026

RESUMO

In yeast, the main ubiquitin ligase responsible for the sorting of proteins to the lysosomal vacuole is Rsp5, a member of the Nedd4 family of ligases whose distinguishing features are a catalytic homologous to E6AP C terminus (HECT) domain and 3 central WW domains that bind PY motifs in target proteins. Many substrates do not bind Rsp5 directly and instead rely on PY-containing adaptor proteins that interact with Rsp5. Recent studies indicate that the activities of these adaptors are elevated when they undergo ubiquitination, yet the mechanism whereby ubiquitination activates the adaptors and how this process is regulated remain unclear. Here, we report on a mechanism that explains how ubiquitination stimulates adaptor function and how this process can be regulated by the Rsp5-associated deubiquitinase, Ubp2. Our overexpression experiments revealed that several adaptors compete for Rsp5 in vivo. We found that the ability of the adaptors to compete effectively was enhanced by their ubiquitination and diminished by a block of their ubiquitination. Ubiquitination-dependent adaptor activation required a ubiquitin-binding surface within the Rsp5 catalytic HECT domain. Finally, like constitutively ubiquitinated adaptors, a Ubp2 deficiency increased both the adaptor activity and the ability to compete for Rsp5. Our data support a model whereby ubiquitinated Rsp5 adaptors are more active when "locked" onto Rsp5 via its N-lobe ubiquitin-binding surface and less active when they are "unlocked" by Ubp2-mediated deubiquitination.


Assuntos
Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Regulação Fúngica da Expressão Gênica , Proteínas de Saccharomyces cerevisiae/genética , Complexos Ubiquitina-Proteína Ligase/genética , Ubiquitinação , Endopeptidases/deficiência , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Microrganismos Geneticamente Modificados/genética , Microrganismos Geneticamente Modificados/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Complexos Ubiquitina-Proteína Ligase/metabolismo
4.
Vet J ; 212: 71-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27256028

RESUMO

In order to determine the comparative efficacy of vaccines administered intranasally or orally to protect puppies from disease subsequent to experimental infection with Bordetella bronchiseptica (Bb), a randomized controlled trial was performed using 48 approximately 8-week-old specific pathogen free, Bb naive Beagle puppies. Puppies were randomized into three groups and administered vaccines containing Bb intranasally or orally, or a placebo intranasally. Twenty-one days later, all dogs were challenge exposed via aerosol administration of Bb. Clinical signs, nasal bacterial shedding and immune responses were monitored for 28 days after challenge. Intranasally vaccinated puppies had significantly lower rates of coughing, nasal discharge, retching and sneezing (i.e. were less sick clinically) than control puppies. The distinction between the orally vaccinated puppies and the control puppies was less consistent. The orally vaccinated puppies had less coughing and less retching than the control puppies, but nasal discharge and sneezing did not differ from control animals. Orally vaccinated puppies had higher rates of coughing, nasal discharge, retching and sneezing than the intranasally vaccinated puppies. Although both intranasal and oral Bb vaccines stimulated immune responses associated with disease sparing following Bb infection, the intranasal route of delivery conferred superior clinical outcomes. The observed difference in clinical efficacy suggests the need to question the rationale for the use of currently available orally administered Bb vaccines.


Assuntos
Vacinas Bacterianas/imunologia , Infecções por Bordetella/veterinária , Bordetella bronchiseptica/imunologia , Doenças do Cão/prevenção & controle , Administração Intranasal/veterinária , Administração Oral , Animais , Derrame de Bactérias , Infecções por Bordetella/microbiologia , Infecções por Bordetella/prevenção & controle , Doenças do Cão/microbiologia , Cães , Feminino , Masculino , Organismos Livres de Patógenos Específicos
5.
J Dairy Sci ; 97(7): 4639-48, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24835974

RESUMO

Four cohorts of nonlactating, pregnant dairy cows (n=50, 47, 45, and 42) were individually fed indoors to determine the amount of feed required for body weight (BW) gain from autumn pasture and commonly used supplementary feeds. These results were used to estimate the apparent efficiency with which metabolizable energy (ME) is used for BW gain (app_kg). Control cows were offered autumn pasture to estimated maintenance requirements (~0.55 MJ of ME/kg of BW(0.75)), with an additional 20 MJ of ME/d allocated for pregnancy and activity. All other cows received the same allowance of autumn pasture and an additional allowance (2.5 or 5.0 kg of dry matter/d) of autumn pasture (Past), spring pasture silage (Psil), maize silage (Msil), cracked maize grain (Mgr), or palm kernel expeller (PKE), resulting in a total of 11 treatments. Individual cow dry matter intake was determined daily; BW was recorded once per week for cohorts 1 and 2, and 3 times per week for cohorts 3 and 4. The ME contents of feeds were estimated from feed quality assays. Regression analyses were used on each feed to determine the ME requirement for 1 kg of BW gain. The app_kg of Past and Msil was 0.34 and 0.47, respectively; these estimates are in line with published literature. The app_kg of Psil (0.50) was consistent with the published kg for spring pasture, from which the silage was made. Palm kernel expeller had the greatest app_kg (0.61). The reasons for this cannot be deduced from the current study but may reflect the relatively high fat content of the feed and the high kg of fat. The app_kg for Mgr was low (0.38) in comparison with the other supplementary feeds and, in particular, relative to its feed ME and published kg estimates. Although the reason for the low app_kg cannot be deduced from the current data, the most plausible reason is the preferential use of propionate-derived glucose for conceptus metabolism rather than BW gain, a factor not accounted for in previous experimental models that did not use late-gestation cows. In summary, the app_kg for autumn pasture was low but consistent with historical growth rate trials in other ruminant species. In comparison, Msil, Psil, and PKE were used with a greater apparent efficiency (app_kg=0.47 to 0.61), but Mgr resulted in a relatively low rate of gain per MJ of ME (app_kg=0.38). These differences have implications for accurate feed budgeting on farm.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios/métodos , Necessidades Nutricionais , Aumento de Peso , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Ingestão de Energia , Feminino , Gravidez , Distribuição Aleatória , Estações do Ano
6.
BMC Biotechnol ; 12: 54, 2012 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-22916790

RESUMO

BACKGROUND: The ability to produce the same recombinant protein in both prokaryotic and eukaryotic cells offers many experimental opportunities. However, the cloning of the same gene into multiple plasmids is required, which is time consuming, laborious and still may not produce soluble, stable protein in sufficient quantities. We have developed a set of expression vectors that allows for ligation-independent cloning and rapid functional screening for protein expression in both E. coli and S. cerevisiae. RESULTS: A set of expression vectors was made that can express the same open reading frame in E. coli (via the T7 phage promoter) and in S. cerevisiae (via the CUP1 or MET25 promoter). These plasmids also contain the essential elements for replication and selection in both cell types and have several advantages: they allow for cloning of genes by homologous recombination in yeast, protein expression can be determined before plasmid isolation and sequencing, and a GST-fusion tag is added to aid in soluble expression and purification. We have also included a TEV recognition site that allows for the specific cleavage of the fusion proteins to yield native proteins. CONCLUSIONS: The dual promoter vectors can be used for rapid cloning, expression, and purification of target proteins from both prokaryotic and eukaryotic systems with the ability to study post-translation modifications.


Assuntos
Clonagem Molecular , Escherichia coli/metabolismo , Plasmídeos/metabolismo , Proteínas Recombinantes de Fusão/biossíntese , Saccharomyces cerevisiae/metabolismo , Endopeptidases/metabolismo , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Fases de Leitura Aberta , Plasmídeos/genética , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/isolamento & purificação
7.
Traffic ; 12(10): 1306-17, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21722280

RESUMO

The endosomal-sorting complex required for transport (ESCRT) apparatus has multiple ubiquitin (Ub)-binding domains and participates in a wide variety of cellular processes. Many of these ESCRT-dependent processes are keenly regulated by Ub, which serves as a lysosomal-sorting signal for membrane proteins targeted into multivesicular bodies (MVBs) and which may serve as a mediator of viral budding from the cell surface. Hints that both ESCRTs and Ub work together in the processes such as cytokinesis, transcription and autophagy are beginning to emerge. Here, we explore the relationship between ESCRTs and Ub in MVB sorting and viral budding.


Assuntos
Complexos Endossomais de Distribuição Requeridos para Transporte/fisiologia , Ubiquitina/fisiologia , Proteínas Virais/metabolismo , Liberação de Vírus/fisiologia , Animais , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Ligação Proteica , Transporte Proteico , Ubiquitina/genética , Ubiquitina/metabolismo
8.
N Z Vet J ; 57(5): 295-8, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19802044

RESUMO

AIM: To determine whether canine respiratory coronavirus (CRCoV) and canine influenza virus (CIV) are present in dogs in New Zealand. METHODS: Serum samples from 251 dogs of varying age, breed and clinical histories were tested for the presence of antibodies to CRCoV and CIV, using indirect fluorescent antibody (IFA) analysis. The population sampled represented a wide geographic area but principally encompassed the central and lower North Island of New Zealand. RESULTS: Seventy-three of the 251 samples (29%) were seropositive for CRCoV. Dogs <2 years old were less likely to be seropositive for CRCoV than older dogs. None was seropositive for CIV. CONCLUSIONS: This study revealed the presence of antibodies to CRCoV in dogs in New Zealand. Young dogs are less likely to be seropositive than older dogs, probably due to increased opportunity for exposure to CRCoV over time. Serum antibodies to CIV were not detected in any of the dogs sampled, suggesting that this virus is unlikely to be present in dogs in New Zealand. CLINICAL RELEVENCE: Canine respiratory coronavirus is present in New Zealand. Although the role of this virus in canine infectious tracheobronchitis has not been fully elucidated, evidence suggests that it may have a causal role in this disease. Veterinarians should consider CRCoV as a differential diagnosis in cases of respiratory disease in dogs in New Zealand. While CIV appears not to be currently present in New Zealand, veterinarians should consider infection with this virus as a differential diagnosis in dogs presenting with respiratory signs.


Assuntos
Infecções por Coronaviridae/veterinária , Coronavirus Canino/isolamento & purificação , Infecções por Orthomyxoviridae/veterinária , Animais , Infecções por Coronaviridae/epidemiologia , Cães , Nova Zelândia/epidemiologia , Infecções por Orthomyxoviridae/epidemiologia , Estudos Soroepidemiológicos
9.
J Cell Biol ; 185(2): 213-24, 2009 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-19380877

RESUMO

Ubiquitin (Ub) sorting receptors facilitate the targeting of ubiquitinated membrane proteins into multivesicular bodies (MVBs). Ub-binding domains (UBDs) have been described in several endosomal sorting complexes required for transport (ESCRT). Using available structural information, we have investigated the role of the multiple UBDs within ESCRTs during MVB cargo selection. We found a novel UBD within ESCRT-I and show that it contributes to MVB sorting in concert with the known UBDs within the ESCRT complexes. These experiments reveal an unexpected level of coordination among the ESCRT UBDs, suggesting that they collectively recognize a diverse set of cargo rather than act sequentially at discrete steps.


Assuntos
Endossomos/metabolismo , Proteínas de Membrana/metabolismo , Complexos Multiproteicos/metabolismo , Transporte Proteico , Ubiquitina/metabolismo , Sequência de Aminoácidos , Animais , Carboxipeptidases/genética , Carboxipeptidases/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Transporte Proteico/fisiologia , Receptores de Fator de Acasalamento/genética , Receptores de Fator de Acasalamento/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismo
10.
J Inorg Biochem ; 101(5): 783-8, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17346797

RESUMO

To further the understanding of the biological importance of metal-binding by avian prion proteins, we have investigated the affinity and selectivity of peptides Hx1 [Ac-HNPGYP-nh] and Hx2 [Ac-NPGYPHNPGYPH-nh] with a range of physiological metals via electrospray ionization mass spectrometry and tyrosine fluorescence emission spectroscopy. Both the hexamer Hx1 and the "dimer" peptide Hx2 bind only one equivalent of Cu(II), although only the latter peptide binds copper with significant affinity (Hx1 K(d)=150+/-35 microM; Hx2 K(d)=1.07+/-0.78 microM, pH 7.0 in 3-(N-morpholino)propanesulfonic acid (MOPS) buffer). Both peptides are selective for Cu(II) over divalent Ca, Co, Mg, Mn, Ni, and Zn. Cyclic voltammetry was used to estimate Cu(II/I) solution potentials at pH 6.8, which were very similar for the two peptides (CuHx1 E degrees'=+350 mV, CuHx2 E degrees'=+320 mV vs. normal hydrogen electrode). These results suggest similar binding modes for the two peptides, and relative stabilization of Cu(I) relative to similar His-Gly-rich peptides in the literature.


Assuntos
Cobre/metabolismo , Príons/metabolismo , Animais , Cátions Bivalentes/metabolismo , Galinhas , Ligação Proteica , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização por Electrospray , Especificidade por Substrato , Tirosina/metabolismo
11.
Endoscopy ; 38(12): 1246-9, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17163327

RESUMO

BACKGROUND AND STUDY AIMS: Patients undergoing pancreaticoduodenectomy develop postoperative complications related to surgery and their disease. Very little data are available on the role or success of endoscopic retrograde cholangiopancreatography (ERCP) in such patients. The aim of this study was to evaluate the indications and role of diagnostic and therapeutic ERCP after pancreaticoduodenectomy for both benign and malignant disease. PATIENTS AND METHODS: This study was a 10-year (1990 - 2000) single institution retrospective review of all ERCPs performed on patients who had undergone pancreaticoduodenectomy surgery. Indications for the ERCP and technical procedural success were studied. RESULTS: 29 patients with a pancreaticoduodenectomy underwent 56 ERCPs. Reasons for surgery were neoplasia and chronic pancreatitis. Indications for ERCP included evaluation of jaundice and pain. Technical success related to the clinical indication (jaundice 69 %, pain 54 %). CONCLUSION: ERCP plays an important role in the management of postpancreatic surgery problems including biliary and anastomotic strictures, and should be the modality of choice. However, surgical technique may make the afferent limb inaccessible, and the ductal anastomosis difficult to identify in patients with some types of pancreaticoduodenectomy. Closer collaboration between surgeon and endoscopist may allow alterations in surgical technique to improve postoperative ERCP success.


Assuntos
Colangiopancreatografia Retrógrada Endoscópica/métodos , Pancreatopatias/diagnóstico , Pancreatopatias/terapia , Pancreaticoduodenectomia/métodos , Oclusão com Balão , Humanos
12.
Poult Sci ; 84(12): 1816-24, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16479936

RESUMO

The purpose of this study was to determine the effect of 2 different bedding types, sand and wood shavings, on the behavior of broiler chickens. In experiment 1, 6 pens were divided down the center and bedded half with sand and half with wood shavings. Male broilers (10/pen) were observed by scan sampling at 5- or 12-min intervals throughout the 6-wk growth period during the morning (between 0800 to 0900 h), afternoon (1200 to 1500 h), and night (2300 to 0600 h). There was a significant behavior x substrate x week interaction during the day (P < 0.0001) and at night (P < 0.0002). Drinking, dustbathing, preening, and sitting increased in frequency on the sand side but decreased on the wood shavings side during the day, as did resting at night. In general, broilers performed a greater proportion of their total behavioral time budget on the sand (P < 0.0001) as they aged. Broilers used the divider between the 2 bedding types to perch; perching behavior peaked during wk 4. In experiment 2, male broilers were housed in 8 pens (50 birds/pen) bedded only in sand or wood shavings. Bedding type had no effect on behavioral time budgets (P = 0.8946), although there were age-related changes in behavior on both bedding types. These results indicate that when given a choice, broilers increasingly performed many of their behaviors on sand, but if only one bedding type was provided they performed those behaviors with similar frequency on sand or wood shavings.


Assuntos
Comportamento Animal , Pisos e Cobertura de Pisos , Abrigo para Animais , Dióxido de Silício , Madeira , Envelhecimento , Animais , Galinhas , Masculino , Fatores de Tempo
13.
Biochemistry ; 43(51): 16086-91, 2004 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-15610003

RESUMO

A chimeric Cu-binding peptide has been designed on the basis of a turn substitution of the prion (PrP) octarepeat Cu-binding site into the engrailed homeodomain helix-turn-helix motif (HTH). This system is a model for the investigation of a single PrP Cu-binding site in a defined protein context. The 28-mer Cu-HTH peptide P7 spectroscopically mimics the PrP octarepeat (P7 = TERRRQQLSHGGGWGEAQIKIWFQNKRA). The Cu(II)-binding affinity of P7 was determined by ESI-MS and tryptophan fluorescence titrations to be K(d) = 2.5 +/- 0.7 microM at pH = 7.0. The quenching of fluorescence of the Trp within the binding loop (underlined above) is pH dependent and highly specific for Cu(II). No Trp quenching was observed in the presence of divalent Zn, Mn, Co, Ni, or Ca ions, and ESI-MS titrations confirmed that these divalent ions do not appreciably bind to P7. The EPR spectrum of Cu(II)-P7 shows that the Cu environment is axial and consistent with 6-coordinate N(3)O(H(2)O)(2) or N(4)(H(2)O)(2) coordination (A( parallel) = 172 x10(-)(4) cm(-)(1); g( parallel) = 2.27), very similar to that of the PrP octarepeat itself. Also like PrP, circular dichroism studies show that apo P7 is predominantly disordered in solution, and the structure is slightly enhanced by Cu binding. These data show the Cu-PrP HTH peptide reproduces the Cu-binding behavior of a single PrP octarepeat in a new context.


Assuntos
Cobre/metabolismo , Engenharia de Proteínas , Proteínas Recombinantes de Fusão/metabolismo , Sequência de Aminoácidos , Dicroísmo Circular , Cristalografia por Raios X , Espectroscopia de Ressonância de Spin Eletrônica , Dados de Sequência Molecular , Príons/genética , Príons/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/química , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização por Electrospray
14.
Neuropathol Appl Neurobiol ; 30(1): 80-9, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14720179

RESUMO

In order to establish the effects of systemically administered progesterone on central nervous system (CNS) remyelination, a toxin-induced model of CNS demyelination was used in which the rate of remyelination is age-dependent. The rapid remyelination in young adult rats allowed an assessment of potential adverse effects of progesterone while the slow remyelination in older adult rats allowed an assessment of its potentially beneficial effects. There was no significant difference in the rate of remyelination between young control and treated animals. However, a modest but significant increase in the extent of oligodendrocyte remyelination in response to progesterone (and a comparable significant decrease in the proportion of axons that remained demyelinated) was observed in older rats 5 weeks after lesion induction. We also found a significant increase in the proportion of Schwann cell remyelinated axons between 3 and 5 weeks after lesion induction that was not apparent in the control animals. These results indicate that progesterone does not inhibit CNS remyelination and that it has a positive modulating effect on oligodendrocyte remyelination in circumstances where it is occurring sub-optimally.


Assuntos
Envelhecimento , Encéfalo/efeitos dos fármacos , Doenças Desmielinizantes/tratamento farmacológico , Progesterona/farmacologia , Animais , Encéfalo/patologia , Preparações de Ação Retardada , Doenças Desmielinizantes/induzido quimicamente , Etídio/toxicidade , Masculino , Neurotoxinas/toxicidade , Oligodendroglia/efeitos dos fármacos , Progesterona/administração & dosagem , Progesterona/sangue , Ratos , Ratos Sprague-Dawley
15.
J Res Natl Inst Stand Technol ; 109(4): 391-405, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-27366620

RESUMO

We demonstrate that dc quantized Hall resistance (dc QHR) guideline properties and dc and ac QHR values can be measured without changing sample probe lead connections at the QHR device, and report ac QHR values that converge to the dc QHR value when using four-terminal-pair ac QHR measurements. This was accomplished during one cooldown using single-series and quadruple-series connections outside the sample probe. The QHR was measured from 0 Hz to 5500 Hz in 1:1 ratio at 20 µA to ±1 part in 10(7) uncertainties with a poor-quality QHR device. A good device would allow an order of magnitude smaller uncertainties over this frequency range. We exchanged positions of the QHR device and reference resistor in the bridge and remeasured the resistance ratios to remove dominant ac bridge effects.

16.
Prog Neurobiol ; 71(1): 49-56, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14611867

RESUMO

The myelin sheaths that surround all but the smallest diameter axons within the mammalian central nervous system (CNS) must maintain their structural integrity for many years. Like many tissues, however, this function is prone to the effects of ageing, and various structural anomalies become apparent in the aged CNS. Similarly, the regenerative process by which myelin sheaths, lost as a consequence of exposure to a demyelinating insult, are restored (remyelination) is also affected by age. As animals grow older, the efficiency of remyelination progressively declines. In this article, we review both phenomena and describe how both can be partially reversed by steroid hormones and their derivatives.


Assuntos
Envelhecimento , Bainha de Mielina/efeitos dos fármacos , Regeneração Nervosa/efeitos dos fármacos , Esteroides/farmacologia , Animais , Sistema Nervoso Central/efeitos dos fármacos , Humanos , Progesterona/farmacologia
17.
Vet Surg ; 31(2): 167-73, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11884962

RESUMO

OBJECTIVE: To determine the effect of acetabular cup temperature and duration of cement pressurization on porosity of the acetabular cement mantel. STUDY DESIGN: In vitro study. METHODS: Twenty-four polyurethane foam blocks prepared for acetabular prosthetic implantation were implanted with polyethylene acetabular cups using four combinations and variations of temperature and pressure: (1) high temperature/short-term pressurization; (2) high temperature/long-term pressurization; (3) low temperature/long-term pressurization; and (4) low temperature short-term pressurization. Five 1-mm-thick slices were taken from the center of each block using a tissue processing system. The slices were scanned into a personal computer using a photo slide scanner. Imaging software was used to determine cement surface area and size, number, and distribution of pores. The quality of the cement-implant interface was subjectively evaluated. Statistical analysis of relative cement porosity was performed by a Kruskal-Wallis analysis of variance comparing the four groups individually and combining the short-term pressurization groups versus the long-term pressurization groups. RESULTS: There were no significant differences in cement porosity between the four test groups (P =.11). There were no significant differences in porosity between the combined groups (P =.48). CONCLUSIONS: There is no benefit in prewarming acetabular cups before implantation. There are no deleterious effects of short-term pressurization of the cement during implantation.


Assuntos
Acetábulo , Cimentos Ósseos , Cimentação/instrumentação , Cães/cirurgia , Prótese de Quadril/veterinária , Animais , Artroplastia de Quadril/veterinária , Fenômenos Biomecânicos , Modelos Animais , Temperatura
18.
Nature ; 411(6840): 957-62, 2001 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-11418861

RESUMO

Tissue injury generates endogenous factors that heighten our sense of pain by increasing the response of sensory nerve endings to noxious stimuli. Bradykinin and nerve growth factor (NGF) are two such pro-algesic agents that activate G-protein-coupled (BK2) and tyrosine kinase (TrkA) receptors, respectively, to stimulate phospholipase C (PLC) signalling pathways in primary afferent neurons. How these actions produce sensitization to physical or chemical stimuli has not been elucidated at the molecular level. Here, we show that bradykinin- or NGF-mediated potentiation of thermal sensitivity in vivo requires expression of VR1, a heat-activated ion channel on sensory neurons. Diminution of plasma membrane phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) levels through antibody sequestration or PLC-mediated hydrolysis mimics the potentiating effects of bradykinin or NGF at the cellular level. Moreover, recruitment of PLC-gamma to TrkA is essential for NGF-mediated potentiation of channel activity, and biochemical studies suggest that VR1 associates with this complex. These studies delineate a biochemical mechanism through which bradykinin and NGF produce hypersensitivity and might explain how the activation of PLC signalling systems regulates other members of the TRP channel family.


Assuntos
Bradicinina/fisiologia , Fator de Crescimento Neural/fisiologia , Fosfatidilinositol 4,5-Difosfato/fisiologia , Receptores de Droga/fisiologia , Animais , Linhagem Celular , Eletrofisiologia , Ativação Enzimática , Feminino , Temperatura Alta , Masculino , Camundongos , Nociceptores/metabolismo , Oócitos/fisiologia , Dor , Proteína Quinase C/metabolismo , Receptor trkA/fisiologia , Receptores de Droga/genética , Transdução de Sinais , Fosfolipases Tipo C/fisiologia , Xenopus laevis
19.
Nucleic Acids Res ; 29(9): 1951-9, 2001 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-11328879

RESUMO

The aim of the present study is to determine the chemical structure and conformation of DNA adducts formed by incubation of the bioactive form of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), N-acetoxy-PhIP, with a single-stranded 11mer oligodeoxyribonucleotide. Using conditions optimized to give the C8-dG-PhIP adduct as the major product, sufficient material was synthesized for NMR solution structure determination. The NMR data indicate that in duplex DNA this adduct exists in equilibrium between two different conformational states. In the main conformer, the covalently bound PhIP molecule intercalates in the helix, whilst in the minor conformation the PhIP ligand is probably solvent exposed. In addition to the C8-dG-PhIP adduct, at least eight polar adducts are found after reaction of N-acetoxy-PhIP with the oligonucleotide. Three of these were purified for further characterization and shown to exhibit lowest energy UV absorption bands in the range 342-347 nm, confirming the presence of PhIP or PhIP derivative. Accurate mass determination of two of the polar adducts by negative ion MALDI-TOF MS revealed ions consistent with a spirobisguanidino-PhIP derivative and a ring-opened adduct. The third adduct, which has the same mass as the C8-dG-PhIP oligonucleotide adduct, may contain PhIP bound to the N2 position of guanine.


Assuntos
Adutos de DNA/química , Adutos de DNA/síntese química , Desoxiguanosina/análogos & derivados , Desoxiguanosina/química , Desoxiguanosina/síntese química , Imidazóis/química , Imidazóis/síntese química , Sequência de Bases , Cromatografia Líquida de Alta Pressão , Ressonância Magnética Nuclear Biomolecular , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/síntese química , Oligodesoxirribonucleotídeos/química , Piridinas/síntese química , Piridinas/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
20.
J Clin Epidemiol ; 54(6): 580-6, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11377118

RESUMO

The purpose of this study was to determine whether individual items in a disability questionnaire were answered differently depending on whether or not the questions were attributed to the upper limb (i.e., "do you have difficulty eating due to your arm or hand problem?" or "do you have difficulty eating?", respectively). The a priori hypothesis was that the same or more disability would be detected by nonattributed items. Four hundred sixty-seven patients with upper extremity disorders completed the SF-36 general health survey, which does not attribute health problems to affected areas. Patients also completed six additional questions, modified from the SF-36, regarding work (four questions) and social function with friends and family (two questions), which attributed their disability to their affected upper extremity. Of 467 patients, 419-431 (89-92%) responded to both versions of the questions. Although we demonstrated a significant order effect (Generalized Estimating Equation; P=.003), comparison of the responses to the six questions showed that for five of the six questions (Generalized Estimating Equation; P< or = .001) patients reported more disability when the questions were worded with attribution to the upper extremity. Even considering the order effect, patients demonstrated a counterintuitive result by reporting more disability when questions were attributed to their affected area. Thus, both the wording of questions and order of questions can significantly affect patients' responses about their disability and raises questions about the validity of patients' reports of their disability.


Assuntos
Avaliação da Deficiência , Indicadores Básicos de Saúde , Adulto , Comorbidade , Pessoas com Deficiência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos de Pesquisa , Autoavaliação (Psicologia) , Inquéritos e Questionários
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