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1.
Environ Geochem Health ; 44(10): 3359-3376, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34570292

RESUMO

Soil degradation, which is linked to poor nutrient management, remains a major constraint to sustained crop production in smallholder urban agriculture (UA) in sub-Saharan Africa (SSA). While organic nutrient resources are often used in UA to complement mineral fertilizers in soil fertility management, they are usually scarce and of poor quality to provide optimum nutrients for crop uptake. Alternative soil nutrient management options are required. This study, therefore, evaluates the short-term benefits of applying an aluminium-based water treatment residual (Al-WTR), in combination with compost and inorganic P fertilizer, on soil chemical properties, and maize (Zea mays L.) productivity and nutrient uptake. An eight-week greenhouse experiment was established with 12 treatments consisting of soil, Al-WTR and compost (with or without P fertilizer). The co-amendment (10% Al-WTR + 10% compost) produced maize shoot biomass of 3.92 ± 0.16 g at 5 weeks after emergence, significantly (p < 0.05) out-yielding the unamended control which yielded 1.33 ± 0.17 g. The addition of P fertilizer to the co-amendment further increased maize shoot yield by about twofold (7.23 ± 0.07 g). The co-amendment (10% Al-WTR + 10% C) with P increased maize uptake of zinc (Zn), copper (Cu) and manganese (Mn), compared with 10% C + P. Overall, the results demonstrate that combining Al-WTR, compost and P fertilizer increases maize productivity and micronutrient uptake in comparison with single amendments of compost and fertilizer. The enhanced micronutrient uptake can potentially improve maize grain quality, and subsequently human nutrition for the urban population of SSA, partly addressing the UN's Sustainable Development Goal number 3 of improving diets.


Assuntos
Oligoelementos , Purificação da Água , Agricultura/métodos , Alumínio , Cobre/metabolismo , Fertilizantes/análise , Humanos , Manganês , Micronutrientes , Minerais/metabolismo , Nitrogênio/análise , Solo/química , Zea mays/metabolismo , Zinco/metabolismo
2.
N Z Vet J ; 69(4): 247-254, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33906586

RESUMO

CASE HISTORY: A kakapo (Strigops habroptilus) chick hatched on an off-shore island of New Zealand with a small white mass protruding through the cranial skin of the head. The chick's growth followed a normal pattern for kakapo but at 3 weeks of age the cranium mass was non-reducible and fixed in place and the chick was removed from the island for diagnostic imaging and hand-rearing. CLINICAL FINDINGS AND TREATMENT: A computed tomography (CT) examination revealed a full-thickness circular defect in the central cranium with suspected herniation of brain and dura. Surgery was performed at 37 days of age, and the herniated dura was dissected from the open fontanelle. Attempts to reduce the herniated tissue were unsuccessful, so the herniated dura and cortex were clamped and resected. The dura was closed and the periosteum of the skull was scarified and monofilament polypropylene mesh was secured tautly over the fontanelle. The mesh graft was infused with autologous bone marrow harvested from the ulna in an attempt to stimulate osteogenesis in the mesh repair. The skin flap was then closed. Post-operative recovery and healing were without complication. A CT examination 4 weeks after surgery showed no recurrence of the hernia, and a composite of mesh and scar over the open fontanelle which had reduced in diameter. The chick was released back onto an off-shore island with a radio transmitter and it continues to be monitored regularly. PATHOLOGICAL FINDINGS: The tissue resected at surgery consisted of a cylindrical core of cerebral parenchyma overlain by a mildly hyperplastic epidermis, and large amounts of oedematous fibrovascular tissue arising from the leptomeninges. DIAGNOSIS: Rostral parietal meningoencephalocoele. CLINICAL RELEVANCE: This is the first report of successful surgical resolution of a meningoencephalocoele in any bird. Techniques from human neurosurgery were adapted for the unique anatomical features of the avian skull. The risks of the procedure included increased intra-cranial pressure resulting in anaesthetic complications or death, cerebrospinal fluid leakage, meningitis or recurrence of the meningoencephalocoele. In the longer term, there was a risk of developmental deficits in cognition or behaviour. None of these complications eventuated in the short to medium term, probably due to the small size of the meningoencephalocoele.


Assuntos
Papagaios , Animais , Encéfalo , Nova Zelândia , Retalhos Cirúrgicos
3.
J Gen Virol ; 100(1): 3-4, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30431412

RESUMO

The family Nodaviridae includes two genera, Alphanodavirus and Betanodavirus. The family name derives from the Japanese village of Nodamura where Nodamura virus was first isolated from Culex tritaeniorhynchus mosquitoes. Virions are non-enveloped and spherical in shape with icosahedral symmetry (T=3) and diameters ranging from 25 to 33 nm. The genome consists of two molecules of single-stranded positive-sense RNA: RNA1 and RNA2. The virion capsid consists of 180 protein subunits arranged on a T=3 surface lattice. Alphanodaviruses infect insects, whereas betanodaviruses are pathogens of fish. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Nodaviridae, which is available at www.ictv.global/report/nodaviridae.


Assuntos
Nodaviridae/classificação , RNA Viral/genética , Proteínas Virais/análise , Vírion/ultraestrutura , Animais , Peixes/virologia , Insetos/virologia , Nodaviridae/genética , Nodaviridae/isolamento & purificação , Nodaviridae/ultraestrutura
4.
Death Stud ; 43(1): 56-61, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29394156

RESUMO

The current study examined the predictive value of cultural versus classic risk and protective factors for suicide in a community sample of 322 ethnic, sexual, and gender minority adults. Cultural factors played a significant and substantial role in predicting suicide attempts (explained 8% of variance in attempts and correctly classified 8.5% of attempters) over and above the classic factors of hopelessness, depression, and reason for living (which explained 17% of variance in attempts and correctly classified 14.1% of attempters). Findings suggest that cultural factors are important to include in standard suicide practice.


Assuntos
Comparação Transcultural , Prevenção do Suicídio , Suicídio/psicologia , Adulto , Etnicidade , Feminino , Humanos , Masculino , Fatores de Proteção , Fatores de Risco , Minorias Sexuais e de Gênero , Ideação Suicida , Tentativa de Suicídio/prevenção & controle , Tentativa de Suicídio/psicologia , Adulto Jovem
5.
J Gen Virol ; 99(12): 1563-1564, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30507372

RESUMO

The family Sarthroviridae includes a single genus, Macronovirus, which in turn includes a single species, Macrobrachium satellite virus 1. Members of this species, named extra small virus, are satellite viruses of Macrobrachium rosenbergii nodavirus, an unclassified virus related to members of the family Nodaviridae. Both viruses have isometric, spherical virions, infect giant freshwater prawns and together cause white tail disease, which is responsible for mass mortalities and severe economic losses in hatcheries and farms. Infection is caused by both vertical and horizontal transmission of virus. Aquatic insects act as a carrier to transmit the disease in prawns. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Sarthroviridae, which is available at www.ictv.global/report/sarthroviridae.


Assuntos
Nodaviridae/crescimento & desenvolvimento , Vírus de RNA/classificação , Vírus de RNA/genética , Vírus Satélites/classificação , Vírus Satélites/genética , Animais , Transmissão de Doença Infecciosa , Transmissão Vertical de Doenças Infecciosas , Insetos Vetores/virologia , Nodaviridae/ultraestrutura , Palaemonidae/virologia , Infecções por Vírus de RNA/transmissão , Infecções por Vírus de RNA/veterinária , Infecções por Vírus de RNA/virologia , Vírus de RNA/isolamento & purificação , Vírus de RNA/ultraestrutura , Vírus Satélites/isolamento & purificação , Vírus Satélites/ultraestrutura , Vírion/ultraestrutura
6.
Psychol Med ; 47(7): 1179-1191, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27998319

RESUMO

BACKGROUND: The public health, public safety and clinical implications of violent events among adults with mental illness are significant; however, the causes and consequences of violence and victimization among adults with mental illness are complex and not well understood, which limits the effectiveness of clinical interventions and risk management strategies. This study examined interrelationships between violence, victimization, psychiatric symptoms, substance use, homelessness and in-patient treatment over time. METHOD: Available data were integrated from four longitudinal studies of adults with mental illness. Assessments took place at baseline, and at 1, 3, 6, 9, 12, 15, 18, 24, 30 and 36 months, depending on the parent studies' protocol. Data were analysed with the autoregressive cross-lag model. RESULTS: Violence and victimization were leading indicators of each other and affective symptoms were a leading indicator of both. Drug and alcohol use were leading indicators of violence and victimization, respectively. All psychiatric symptom clusters - affective, positive, negative, disorganized cognitive processing - increased the likelihood of experiencing at least one subsequent symptom cluster. Sensitivity analyses identified few group-based differences in the magnitude of effects in this heterogeneous sample. CONCLUSIONS: Violent events demonstrated unique and shared indicators and consequences over time. Findings indicate mechanisms for reducing violent events, including trauma-informed therapy, targeting internalizing and externalizing affective symptoms with cognitive-behavioral and psychopharmacological interventions, and integrating substance use and psychiatric care. Finally, mental illness and violence and victimization research should move beyond demonstrating concomitant relationships and instead focus on lagged effects with improved spatio-temporal contiguity.


Assuntos
Vítimas de Crime/estatística & dados numéricos , Hospitalização/estatística & dados numéricos , Pessoas Mal Alojadas/estatística & dados numéricos , Transtornos Mentais/epidemiologia , Violência/estatística & dados numéricos , Adulto , Humanos , Transtornos Mentais/terapia
7.
J Biomech Eng ; 136(2): 021023, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24362893

RESUMO

The present study, through finite element simulations, shows the geometric effects of a bioinspired solid on pressure and impulse mitigation for an elastic, plastic, and viscoelastic material. Because of the bioinspired geometries, stress wave mitigation became apparent in a nonintuitive manner such that potential real-world applications in human protective gear designs are realizable. In nature, there are several toroidal designs that are employed for mitigating stress waves; examples include the hyoid bone on the back of a woodpecker's jaw that extends around the skull to its nose and a ram's horn. This study evaluates four different geometries with the same length and same initial cross-sectional diameter at the impact location in three-dimensional finite element analyses. The geometries in increasing complexity were the following: (1) a round cylinder, (2) a round cylinder that was tapered to a point, (3) a round cylinder that was spiraled in a two dimensional plane, and (4) a round cylinder that was tapered and spiraled in a two-dimensional plane. The results show that the tapered spiral geometry mitigated the greatest amount of pressure and impulse (approximately 98% mitigation) when compared to the cylinder regardless of material type (elastic, plastic, and viscoelastic) and regardless of input pressure signature. The specimen taper effectively mitigated the stress wave as a result of uniaxial deformational processes and an induced shear that arose from its geometry. Due to the decreasing cross-sectional area arising from the taper, the local uniaxial and shear stresses increased along the specimen length. The spiral induced even greater shear stresses that help mitigate the stress wave and also induced transverse displacements at the tip such that minimal wave reflections occurred. This phenomenon arose although only longitudinal waves were introduced as the initial boundary condition (BC). In nature, when shearing occurs within or between materials (friction), dissipation usually results helping the mitigation of the stress wave and is illustrated in this study with the taper and spiral geometries. The combined taper and spiral optimized stress wave mitigation in terms of the pressure and impulse; thus providing insight into the ram's horn design and woodpecker hyoid designs found in nature.


Assuntos
Transferência de Energia/fisiologia , Modelos Biológicos , Espalhamento de Radiação , Som , Vibração , Animais , Força Compressiva/fisiologia , Simulação por Computador , Módulo de Elasticidade/fisiologia , Humanos , Pressão , Resistência ao Cisalhamento/fisiologia , Estresse Mecânico , Resistência à Tração/fisiologia , Viscosidade
8.
Plant Dis ; 95(6): 697-704, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30731899

RESUMO

Bacterial fruit blotch (BFB), caused by the seedborne, gram-negative bacterium Acidovorax citrulli, is a serious threat to cucurbit seed and fruit production worldwide. Because of the lack of effective management strategies, we investigated the efficacy of a nonpathogenic A. citrulli strain as a biological control seed treatment for BFB. For this study, we generated a type III secretion system mutant of A. citrulli, AAC00-1ΔhrcC, that was nonpathogenic on watermelon but retained its ability to colonize germinating watermelon seed. With watermelon seed naturally infested with A. citrulli, AAC00-1ΔhrcC reduced BFB seedling transmission by 81.8% relative to control seed. In comparison, another A. citrulli antagonist, A. avenae strain AAA 99-2, reduced BFB seedling transmission by 74.6% for seed samples from the same lot. Additionally, when female watermelon blossoms were protected with AAC00-ΔhrcC and subsequently challenged with AAC00-1, the resulting seedlots displayed 8% BFB seedling transmission. This was not significantly different than seed from blossoms protected with AAA 99-2 (4%) but significantly less than those from blossoms protected with 0.1 M phosphate-buffered saline (36%). These results suggest that nonpathogenic A. citrulli has potential as a biological control seed treatment component in a comprehensive BFB management program.

9.
J Mech Behav Biomed Mater ; 119: 104400, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33893020

RESUMO

In this study, ram impacts at 5.5 m/s are simulated through finite element analysis in order to study the mechanical response of the brain. A calibrated internal state variable inelastic constitutive model was implemented into the finite element code to capture the brain behavior. Also, constitutive models for the horns were calibrated to experimental data from dry and wet horn keratin at low and high strain rates. By investigating responses in the different keratin material states that occur in nature, the bounds of the ram brain response are quantified. An acceleration as high as 607 g's was observed, which is an order of magnitude higher than predicted brain injury threshold values. In the most extreme case, the maximum tensile pressure and maximum shear strains in the ram brain were 245 kPa and 0.28, respectively. Because the rams do not appear to sustain injury, these impacts could give insight to the threshold limits of mechanical loading that can be applied to the brain. Following this motivation, the brain injury metric values found in this research could serve as true injury metrics for human head impacts.


Assuntos
Lesões Encefálicas , Encéfalo , Aceleração , Animais , Fenômenos Biomecânicos , Análise de Elementos Finitos , Cabeça , Humanos , Masculino , Ovinos , Estresse Mecânico
10.
Comput Methods Biomech Biomed Engin ; 24(11): 1169-1183, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33635182

RESUMO

Chronic Traumatic Encephalopathy (CTE) affects a significant portion of athletes in contact sports but is difficult to quantify using clinical examinations and modeling approaches. We use an in silico approach to quantify CTE biomechanics using mesoscale Finite Element (FE) analysis that bridges with macroscale whole head FE analysis. The sulci geometry produces complex stress waves that interact with one another to create increased shear stresses at the sulci depth that are significantly larger than in analyses without sulci (from 0.5 to 18.0 kPa). Sulci peak stress concentration regions coincide with experimentally observed CTE sites documented in the literature. HighlightsSulci introduce stress localizations at their depth in the gray matterSulci stress fields interact to produce stress concentration sites in white matterDifferentiating brain tissue properties did not significantly affect peak stresses.


Assuntos
Encefalopatia Traumática Crônica , Esportes , Encéfalo , Análise de Elementos Finitos , Cabeça , Humanos
11.
Science ; 160(3823): 67-8, 1968 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-4171032

RESUMO

Local business-day traffic determines the diurnal carbon monoxide concentrations at individual sites in Manhattan. Concentrations during the day can be predicted from readings taken in early morning.


Assuntos
Monóxido de Carbono/análise , Emissões de Veículos , Poluição do Ar/prevenção & controle , Comércio , Cidade de Nova Iorque , Periodicidade , Estados Unidos , População Urbana
12.
Bioinformatics ; 22(22): 2739-45, 2006 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-16954138

RESUMO

MOTIVATION: Using stable isotopes in global proteome scans, labeled molecules from one sample are pooled with unlabeled molecules from another sample and subsequently subjected to mass-spectral analysis. Stable-isotope methodologies make use of the fact that identical molecules of different stable-isotope compositions are differentiated in a mass spectrometer and are represented in a mass spectrum as distinct isotopic clusters with a known mass shift. We describe two multivariable linear regression models for (16)O/(18)O stable-isotope labeled data that jointly model pairs of resolved isotopic clusters from the same peptide and quantify the abundance present in each of the two biological samples while concurrently accounting for peptide-specific incorporation rates of the heavy isotope. The abundance measure for each peptide from the two biological samples is then used in down-stream statistical analyses, e.g. differential expression analysis. Because the multivariable regression models are able to correct for the abundance of the labeled peptide that appear as an unlabeled peptide due to the inability to exchange the natural C-terminal oxygen for the heavy isotope, they are particularly advantageous for a two-step digestion/labeling procedure. We discuss how estimates from the regression model are used to quantify the variability of the estimated abundance measures for the paired samples. Although discussed in the context of (16)O/(18)O stable-isotope labeled data, the multivariable regression models are generalizable to other stable-isotope labeled technologies.


Assuntos
Biologia Computacional/métodos , Espectrometria de Massas/métodos , Proteínas/química , Proteômica/métodos , Análise de Regressão , Algoritmos , Humanos , Isótopos , Cinética , Análise Multivariada , Isótopos de Oxigênio/química , Mapeamento de Peptídeos , Soroalbumina Bovina/química , Transferrina/química , Tripsina/química
13.
J Dent Res ; 86(6): 556-9, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17525357

RESUMO

Osteoclasts play a vital role in orthodontic tooth movement. Transactivation of nuclear factor kappaB (NFkappaB) by phosphorylation of the p65 component of NFkappaB at amino acid 536 (p65*(536)) plays a role in osteoclast differentiation stimulated by receptor activator of nuclear factor kappaB-ligand (RANK-L). We hypothesized that this transactivation pathway might be involved in the responses of alveolar bone cells during orthodontic tooth movement. We detected sharp increases in the levels of p65*(536) 3 and 12 hrs after the application of orthodontic stimuli in rats. In cell culture, osteoclast-like cells displayed no changes in p65*(536) in response to RANK-L, but levels rapidly increased after the cells were mechanically scraped. We conclude that p65*(536) is produced rapidly in response to orthodontic stimuli and mechanical insults, and may be important in bone remodeling associated with orthodontic tooth movement.


Assuntos
Osteoclastos/metabolismo , Técnicas de Movimentação Dentária , Fator de Transcrição RelA/metabolismo , Processo Alveolar/citologia , Animais , Fenômenos Biomecânicos , Diferenciação Celular/genética , Linhagem Celular , Eletroforese em Gel de Poliacrilamida , Immunoblotting , Técnicas Imunoenzimáticas , Imuno-Histoquímica , Masculino , Camundongos , Fosforilação , Ligante RANK/metabolismo , Ratos , Ratos Sprague-Dawley , Estresse Mecânico , Fatores de Tempo , Fator de Transcrição RelA/análise , Ativação Transcricional/genética
15.
Biotech Histochem ; 92(7): 459-466, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28910197

RESUMO

It is difficult to identify reliable reference genes for transcriptomic analyses in biofluids such as saliva. This situation is particularly relevant for the newborn population, where rapid development is associated with dynamic changes in gene expression. Real-time gene expression monitoring holds great promise for elucidating disrupted pathways that result in morbidities unique to this population, such as retinopathy of prematurity, but its impact depends on identifying stable and consistently expressed genes across a wide range of gestational ages. We extracted total RNA from 400 neonatal saliva samples (postconceptional ages: 32 5/7 to 48 2/7 weeks), converted it to cDNA, and pre-amplified and analyzed it by qPCR for three commonly used reference genes, ACTB, GAPDH, and YWHAZ. Relative quantification was determined using the Δ Ct method. Data were analyzed as a whole and also stratified by age and sex. Descriptive statistics and homogeneity of variance were performed to identify optimal reference genes. Data analyzed from all ages and both sexes showed significant expression variation for ACTB, while GAPDH and YWHAZ showed greater stability. Male infants exhibited increased expression variation compared to females for ACTB, but neither GAPDH nor YWHAZ showed significant variance for either sex. We suggest that ACTB is an unreliable reference gene for the newborn population. Males showed significantly more variation in ACTB expression compared to females, which suggests a sex-specific developmental role for this biomarker. By contrast, GAPDH and YWHAZ were less variable and therefore preferable for use in neonates. Our findings may improve the use of reference genes for the RT-qPCR platform in the newborn over a wide range of gestational ages, thereby minimizing the likelihood of erroneous interpretation of gene expression during rapid growth, development, and differentiation.


Assuntos
Perfilação da Expressão Gênica , Reação em Cadeia da Polimerase em Tempo Real , Saliva/química , Proteínas 14-3-3 , Biomarcadores/química , Feminino , Expressão Gênica , Perfilação da Expressão Gênica/normas , Variação Genética , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora) , Humanos , Recém-Nascido , Masculino , Padrões de Referência
16.
Acta Biomater ; 48: 300-308, 2017 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-27793720

RESUMO

This paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. Samples were tested in the rehydrated (35wt% water) and ambient dry (10wt% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. The horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. The structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram's impacting each other as well as being useful for other analysis regarding horn keratin on other animals. STATEMENT OF SIGNIFICANCE: The horn of the bighorn sheep is an anisotropic composite composed of keratin that is highly sensitive to moisture content. Keratin is also found in many other animals in the form of hooves, claws, beaks, and feathers. Only one previous study contains high rate experimental data, which was performed in the dry condition and only in compression. Considering the bighorn sheep horns' protective role in high speed impacts along with the moisture and strain rate sensitivity, more high strain rate data is needed to fully characterize and model the material. This study provides high strain rate results demonstrating the effects of moisture, anisotropy, and stress state. As a result, the comprehensive data allows modeling efforts to be greatly improved.


Assuntos
Cornos/química , Umidade , Queratinas/química , Estresse Mecânico , Animais , Anisotropia , Fenômenos Biomecânicos , Força Compressiva , Cornos/ultraestrutura , Processamento de Imagem Assistida por Computador , Carneiro da Montanha , Estatística como Assunto , Resistência à Tração
17.
J Colloid Interface Sci ; 296(1): 284-91, 2006 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-16203010

RESUMO

The cycle of loading and unloading of a spherically-tipped probe against an adhesive, viscoelastic plane specimen is studied by numerical integration of the relations between crack speed and apparent surface energy previously found for a linear 3-element viscoelastic solid with a Maugis-Dugdale law of force across the crack. It is found that even when the rate of loading is so slow that the loading and unloading curves almost coincide, suggesting purely elastic behaviour, the pull-off force can be appreciably greater than the elastic (JKR) value. When the normal force is modulated with a small amplitude sinusoidal variation during unloading--in order to find the contact stiffness--the contact radius barely changes, and the stiffness is close to that for a rigid flat punch instead of having the expected JKR value.

18.
J Colloid Interface Sci ; 296(1): 178-88, 2006 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-16168427

RESUMO

Adhesion of micron-scale probes with model poly(dimethylsiloxane), PDMS, elastomers was studied with a depth-sensing nanoindenter under oscillatory loading conditions. For contacts between diamond indenters (radius R = 5 or 10 microm) and PDMS, force-displacement curves were highly reversible and consistent with Johnson-Kendall-Roberts (JKR) behavior. However, our experiments have revealed striking differences between the experimental measurements of tip-sample interaction stiffness and the theoretical JKR stiffness. The measured stiffness was always greater than zero, even in the reflex portion of the curve (between the maximum adhesive force and release), where the JKR stiffness is negative. This apparent paradox can be resolved by considering the effects of viscoelasticity of PDMS on an oscillating crack tip in a JKR contact. Under well described conditions determined by oscillation frequency, sample viscoelastic properties, and the Tabor parameter (with variables R, reduced elastic modulus, E*, and interfacial energy, deltagamma), an oscillating crack tip will neither advance nor recede. In that case, the contact size is fixed (like that of a flat punch) at any given point on the load-displacement cycle, and the experimentally measured stiffness is equal to the equivalent punch stiffness. For a fixed oscillation frequency, a transition between JKR and punch stiffness can be brought about by an increase in radius of the probe or a decrease in PDMS modulus. Additionally, varying the oscillation frequency for a fixed E*, R, and deltagamma also resulted in transition between JKR and punch stiffness in a predictable manner. Comparisons of experiments and theory for an oscillating viscoelastic JKR contact are presented. The storage modulus and surface energy from nanoscale JKR stiffness measurements were compared to calculated values and those measured with conventional nanoindentation and JKR force-displacement analyses.

19.
Oncogene ; 20(30): 4085-94, 2001 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-11494136

RESUMO

Permeability transition, and a subsequent drop in mitochondrial membrane potential (DeltaPsi(m)), have been suggested to be mechanisms by which cytochrome c is released from the mitochondria into the cytosol during apoptosis. Furthermore, a drop in DeltaPsi(m) has been suggested to be an obligate early step in the apoptotic pathway. Didemnin B, a branched cyclic peptolide described to have immunosuppressive, anti-tumour, and anti-viral properties, induces rapid apoptosis in a range of mammalian cell lines. Induction of apoptosis by didemnin B in cultured human pro-myeloid HL-60 cells is the fastest and most complete ever described with all cells being apoptotic after 3 h of treatment. By utilizing the system of didemnin B-induced apoptosis in HL-60 cells, and the potent inhibitors of mitochondrial permeability transition, cyclosporin A and bongkrekic acid, we show that permeability transition as determined by changes in DeltaPsi(m) and mitochondrial Ca2+ fluxing, is not a requirement for apoptosis or cytochrome c release. In this system, changes in mitochondrial membrane potential and cytochrome c release are shown to be dependent on caspase activation, and to occur concurrently with the release of caspase-9 from mitochondria, genomic DNA fragmentation and apoptotic body formation.


Assuntos
Apoptose/efeitos dos fármacos , Caspases/fisiologia , Grupo dos Citocromos c/metabolismo , Depsipeptídeos , Membranas Intracelulares/fisiologia , Canais Iônicos , Mitocôndrias/enzimologia , Peptídeos Cíclicos/farmacologia , Apoptose/fisiologia , Ácido Bongcréquico/farmacologia , Linfoma de Burkitt/patologia , Sinalização do Cálcio , Caspase 9 , Caspases/metabolismo , Ciclosporina/farmacologia , Fragmentação do DNA , Ativação Enzimática , Células HL-60/efeitos dos fármacos , Células HL-60/ultraestrutura , Humanos , Membranas Intracelulares/efeitos dos fármacos , Melanoma/patologia , Potenciais da Membrana/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Mitocôndrias/efeitos dos fármacos , Proteínas de Transporte da Membrana Mitocondrial , Poro de Transição de Permeabilidade Mitocondrial , Permeabilidade/efeitos dos fármacos , Tapsigargina/farmacologia , Células Tumorais Cultivadas
20.
Biotech Histochem ; 90(8): 581-6, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26052888

RESUMO

Analysis of saliva for clinical monitoring and biomarker detection holds great promise for improving health care. Commercially available assays are not intended for use with neonates, however, and collection and processing of saliva for subsequent transcriptomic analysis presents unique challenges in this population. We compared RNA yield, quality, stability and RT-qPCR performance for two commonly used commercial systems: the Qiagen RNeasy Protect Saliva Mini Kit(®) and the DNA Genotek Oragene•RNA(®) assay. Two 10 µl saliva samples were collected from ten newborns and stabilized for each assay. Total RNA was extracted following incubation for 3, 10, 15 or 20 days. Total RNA extracted from each assay was analyzed for integrity, quality and quantity using the Agilent BioAnalyzer 2100. RT-qPCR was performed for the reference gene, GAPDH, to assess subsequent performance of the extracted RNA. Although the DNA Genotek extraction protocol required nearly twice the time of the Qiagen protocol, RNA integrity did not differ between the kits. RNA concentration using the DNA Genotek assay, however, was 3,264 pg/µl (range: 262 - 10,336 pg/µl) compared to 822.4 pg/µl (range: 0 - 1,856 pg/µl) for the Qiagen protocol. Linear regression analysis showed a stronger correlation between the threshold cycle and RNA concentration using DNA Genotek (r(2) = 0.356) compared to Qiagen (r(2) = 0.0331). Our results suggest that although the Qiagen assay may reduce overall extraction time, RNA yield and performance in subsequent transcriptomic analysis is more robust using the DNA Genotek assay.


Assuntos
Testes Genéticos/métodos , Triagem Neonatal/métodos , RNA/genética , Saliva/química , Análise de Sequência de RNA/métodos , Manejo de Espécimes/métodos , Humanos , Recém-Nascido , Ácidos Nucleicos , RNA/química , RNA/isolamento & purificação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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