RESUMEN
Visual short-term memory (VSTM) capacity is often assessed using change detection tasks, and individual differences in performance have been shown to predict cognitive aptitudes across a range of domains in children and adults. We recently showed that intelligence correlates with an attentional component necessary for change detection rather than with memory capacity per se (Cusack, Lehmann, Veldsman, & Mitchell, 2009). It remained unclear, however, whether different attentional strategies during change detection have most impact during the encoding or maintenance of information. Here we present recent findings from our laboratory supporting the hypothesis that attentional selection during encoding dominates individual differences in change detection measures of visual short-term memory. In a first study, we unpredictably varied whether short-term memory was probed using change detection or whole report, encouraging participants to adopt the same encoding strategy throughout the tasks. Change detection performance of lower-IQ individuals improved. In a second study, we found that deficits in top-down attentional selectivity can be alleviated in participants with low change detection performance by providing helpful grouping information during encoding. Finally, a meta-analysis of neuroimaging data from 112 participants performing a variety of VSTM tasks showed that performance correlates with activity in several parietal and frontal regions during the encoding but not the maintenance phase. Taken together, these results support the notion that encoding strategy and not short-term memory capacity itself largely determines individual differences in visual change detection performance.
Asunto(s)
Atención/fisiología , Discriminación en Psicología/fisiología , Inteligencia/fisiología , Memoria a Corto Plazo/fisiología , Percepción Visual/fisiología , Adulto , Lóbulo Frontal/fisiología , Humanos , Individualidad , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Lóbulo Parietal/fisiología , Valores de Referencia , Detección de Señal Psicológica/fisiología , Adulto JovenRESUMEN
Gene-directed enzyme prodrug therapy is a promising approach to the local management of cancer and a number of gene prodrug combinations have entered clinical trials. The antitumor activity of Escherichia coli nitroreductase (NTR) in combination with the prodrug CB1954 relies on the reduction of the nitro groups to reactive N-hydroxylamine intermediates that are toxic in proliferating and nonproliferating cells. We examined whether secondary metabolic activation of the N-hydroxylamines by sulfotransferases or acetyltransferases altered cell responsiveness to the drug. We evaluated the coexpression of NTR with the human cytosolic sulfotransferases SULT1A1, 1A2, 1A3, 1E1 and 2A1, or the human arylamine N-acetyltransferases NAT1 and NAT2 on SKOV3 cell survival. Only NAT2 significantly altered the toxicity of CB1954, decreasing the IC(50) 16-fold from 0.61 to 0.04 microM. These results suggest that one or more of the N-hydroxyl metabolites are a substrate for O-acetylation by NAT2. We also examined the bystander effect of SKOV3 cells expressing NTR or NTR plus NAT2. Addition of the acetyltransferase resulted in a significant decreased bystander effect (P>0.01), possibly due to a lower concentration of reactive metabolites in the culture medium. These results suggest that a combination of bacterial NTR and NAT2 may provide a greater clinical response at therapeutic concentrations of CB1954 provided the reduction in bystander effect is not clinically significant. Moreover, endogenous NAT2, which is localized predominantly in the liver and gut, may be involved in the dose-limiting hepatic toxicity and gastrointestinal side effects seen in patients treated with the higher doses of CB1954.
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Antineoplásicos/metabolismo , Arilamina N-Acetiltransferasa/metabolismo , Aziridinas/metabolismo , Quimioterapia/métodos , Escherichia coli/enzimología , Nitrorreductasas/metabolismo , Neoplasias Ováricas/tratamiento farmacológico , Profármacos/metabolismo , Análisis de Varianza , Antineoplásicos/farmacología , Antineoplásicos/toxicidad , Aziridinas/farmacología , Aziridinas/toxicidad , Western Blotting , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Cartilla de ADN/genética , Femenino , Citometría de Flujo , Humanos , Hidroxilaminas/metabolismo , Concentración 50 Inhibidora , Nitrorreductasas/farmacología , Plásmidos/genética , Profármacos/farmacología , Profármacos/toxicidad , Sulfotransferasas/metabolismoRESUMEN
Polygonum odoratum (= Persicaria odorata), known as rau ram or sang hum, is native to southeastern Asia and is a common herb in Vietnamese cuisine (1). It has been studied most extensively for its aromatic compound content (2). In Florida, rau ram commonly is grown hydroponically in greenhouses using large, cement beds with recirculated water. The plants form dense mats from which new growth is trimmed for market. During January of 2002, a severe dieback was observed in one production house in Saint Lucie County, FL. Plants with less severe symptoms were yellowed and stunted. Roots of symptomatic plants were largely decayed with root symptoms beginning as a tip necrosis. The cortex of severely affected roots slipped off easily, leaving a stringy vascular system. Plating of symptomatic tissue from 20 randomly selected plant samples was performed with multiple general and selective media including potato dextrose agar, corn meal agar with pimaricin, ampicillin, rifampicin, and pentachloronitrobenzene (PARP) (3). All colonies produced were identified as Pythium helicoides Drechsler on the basis of sporangial, oogonial, and antheridial characteristics (4). Isolates had proliferous, obovoid, papillate sporangia, and were homothallic with smooth-walled oogonia and thick-walled, aplerotic oospores. Multiple antheridial attachments per oogonium were common with the antheridium attached along its entire length. Pathogenicity tests were conducted using P. odoratum plants grown from commercial transplants. Two tests were performed. Each test was conducted using eight inoculated and eight control plants. In the first test, plants were maintained in 10-cm pots immersed in sterilized pond water for the duration of the test. Plants were inoculated with five 7- × 70-mm sections of freshly growing mycelial culture per plant using 10-day-old cultures of Pythium helicoides grown on water agar. Chlorosis was observed at approximately 2 months after inoculation. Root necrosis was observed in inoculated plants approximately 5 months after inoculation. This test was performed in the greenhouse with temperatures ranging from 20 to 30°C. The second test was performed in growth chambers at 35 to 40°C. Plants were maintained in 10-cm pots immersed in Hoagland's solution and were inoculated with four 6-mm plugs per plant. Symptoms were observed on inoculated plants at this temperature within 1 week of inoculation. No chlorosis or root decay was observed in noninoculated, immersed plants. The pathogen was reisolated from inoculated, symptomatic tissue. To our knowledge, this is the first report of root rot of P. odoratum caused by Pythium helicoides. References: (1) R. E. Bond. Herbarist 55:34, 1989. (2) N. X. Dung et al. J. Essent. Oil Res. 7:339, 1995. (3) M. E. Kannwischer and D. J. Mitchell. Phytopathology 68:1760, 1978. (4) A. J. van der Plaats-Niterink. Monograph of the Genus Pythium. Vol. 21, Studies in Mycology. Centraalbureau voor Schimmelcutltures, Baarn, The Netherlands, 1981.
RESUMEN
The ribosomal internal transcribed spacer 1 region was sequenced for 10 species of Pythium and eight species of Phytophthora. Alignment of the sequences revealed considerable sequence microheterogeneity, which was utilized to prepare a capture probe of unique sequence for each species. The capture probes were tested by PCR ELISA, combining the sensitivity and specificity of the polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). The probes were entirely species specific, enabling the detection and identification of the amplified DNA of species from individual cultures or from mixed samples of the DNAs of two different species. This approach to species identification, which provides a molecular technology to process large numbers of samples and still identify the fungi with a high level of confidence, may greatly reduce the resources and the time of highly trained specialists currently needed to identify these important species of plant pathogenic fungi.
Asunto(s)
ADN Espaciador Ribosómico/análisis , Phytophthora/genética , Reacción en Cadena de la Polimerasa/métodos , Pythium/genética , Secuencia de Bases , Capsicum/microbiología , ADN Espaciador Ribosómico/genética , Digoxigenina , Ensayo de Inmunoadsorción Enzimática , Solanum lycopersicum/microbiología , Datos de Secuencia Molecular , Phytophthora/clasificación , Raíces de Plantas/microbiología , Pythium/clasificación , Alineación de Secuencia , Especificidad de la EspecieRESUMEN
This study compares a comprehensive method of collecting injury data from sports medicine clinics, with a more simplified method of injury surveillance. The sports medicine injury surveillance (SMIS) project was implemented in a group of five allied sports medicine clinics in Melbourne. over two consecutive years. The injury surveillance method used in the second year (SMIS2) was a simplified version of that used in the first year (SMIS1). Methodological differences in the injury surveillance systems included form design, staff commitment and training, auditing process, financial incentives offered and employment of a project officer. Data were collected on 6479 new sports injury patients during SMIS1 and on 1682 patients during SMIS2. Comparative data from the two years of injury surveillance included patient profile (gender. age. days from injury to treatment, sport and context of injury) and injury information (site, cause and nature of injury). The SMIS2 methodology was associated with a lower sensitivity (p < 0.001) and a higher proportion of missing information (p < 0.001) than the SMIS1 methodology. There was also a significant difference in the nature and cause of injury variables (p < 0.001) between SMIS1 and SMIS2 and this was associated with coding changes. This study shows that the method of data collection influences both the proportion of missing information and the sensitivity of the system. A comprehensive method of injury surveillance will lead to a more complete data collection process. Methodological differences, however, do not appear to substantially alter conclusions about general patient characteristics, but do have some influence on the accuracy with which broad injury data are identified. Notwithstanding these comments, this study shows that injury surveillance activities can be successfully implemented in sports medicine clinics.
Asunto(s)
Instituciones de Atención Ambulatoria/estadística & datos numéricos , Traumatismos en Atletas/epidemiología , Vigilancia de la Población/métodos , Medicina Deportiva/estadística & datos numéricos , Distribución de Chi-Cuadrado , Femenino , Humanos , Masculino , Nueva Gales del Sur/epidemiología , Sensibilidad y Especificidad , Encuestas y CuestionariosRESUMEN
T cell-mediated destruction of the myelin sheath causes inflammatory damage of the CNS in multiple sclerosis (MS). The major T and B cell responses in MS patients who are HLA-DR2 (about two-thirds of MS patients) react to a region between residues 84 and 103 of myelin basic protein (1 ). The crystal structure of HLA-DR2 complexed with myelin basic protein(84-102) confirmed that Lys(91) is the major TCR contact site, whereas Phe(90) is a major anchor to MHC and binds the hydrophobic P4 pocket (2 ). We have tested peptides containing repetitive 4-aa sequences designed to bind critical MHC pockets and to interfere with T cell activation. One such sequence, EYYKEYYKEYYK, ameliorates experimental autoimmune encephalomyelitis in Lewis rats, an animal model of MS.
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Encefalomielitis Autoinmune Experimental/inmunología , Antígenos de Histocompatibilidad/metabolismo , Péptidos/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Adyuvantes Inmunológicos/farmacología , Secuencia de Aminoácidos , Animales , Sitios de Unión/genética , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Femenino , Antígeno HLA-DR2/metabolismo , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Esclerosis Múltiple/tratamiento farmacológico , Esclerosis Múltiple/inmunología , Proteína Básica de Mielina/genética , Proteína Básica de Mielina/inmunología , Proteína Básica de Mielina/farmacología , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/inmunología , Fragmentos de Péptidos/farmacología , Péptidos/genética , Péptidos/farmacología , Ratas , Ratas Endogámicas Lew , Homología de Secuencia de Aminoácido , Linfocitos T/inmunologíaRESUMEN
Trimethylamine dehydrogenase (TMADH) from the bacterium Methylophilus methylotrophus (sp. W(3)A(1)) and its C30A mutant were inactivated with three known inactivators of monoamine oxidase, namely, phenylhydrazine, N-cyclopropyl-alpha-methylbenzylamine, and 1-phenylcyclopropylamine. All three compounds irreversibly inactivated both the wild-type and C30A mutant enzymes, although phenylhydrazine was 10 times more potent than N-cyclopropyl-alpha-methylbenzylamine, which was much more potent than 1-phenylcyclopropylamine. The change in the UV--visible absorption spectra upon modification indicated that the flavin was modified. In the case of the C30A mutant, the absence of a covalent attachment of the flavin to the polypeptide has permitted LC-electrospray mass spectrometry of the reaction product to be undertaken, demonstrating new mass peaks corresponding to various chemically modified forms of the flavin cofactor. In the case of N-cyclopropyl-alpha-methylbenzylamine, masses corresponding to hydroxy-FMN and hydroxyriboflavin were detected. 1-Phenylcyclopropylamine inactivation of the C30A mutant produced three modified flavins, as evidenced by the electrospray mass spectrum: hydroxy-FMN, FMN plus C(6)H(5)COCH(2)CH(2), and hydroxy-FMN plus C(6)H(5)COCH(2)CH(2). Phenylhydrazine inactivation of the C30A mutant gave at least seven different modified flavins: hydroxyriboflavin, hydroxy-FMN, two apparently isomeric compounds corresponding to hydroxy-FMN plus one phenyl group, two apparently isomeric compounds corresponding to FMN plus one phenyl group, and FMN plus two phenyl groups. Covalent flavin adduct formation appears to be the only modification because dialysis of the inactive enzyme followed by reconstitution with FMN restores the enzyme activity to that of a noninactivated control.
Asunto(s)
Bencilaminas/farmacología , Ciclopropanos/farmacología , Inhibidores Enzimáticos/farmacología , Oxidorreductasas N-Desmetilantes/antagonistas & inhibidores , Oxidorreductasas N-Desmetilantes/genética , Fenilhidrazinas/farmacología , Alanina/genética , Cromatografía Liquida , Cisteína/genética , Activación Enzimática/efectos de los fármacos , Mononucleótido de Flavina/química , Inhibidores de la Monoaminooxidasa/farmacología , Mutagénesis Sitio-Dirigida , Oxidorreductasas N-Desmetilantes/química , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría UltravioletaRESUMEN
Incubation of 1-phenylcyclopropylamine with bovine liver MAO (MAO B), followed by complete enzymatic digestion to single amino acid residues and subsequent analysis by on-line liquid chromatography-electrospray ionization mass spectrometry, was used to investigate the resulting flavin adduct structure.
Asunto(s)
Ciclopropanos/farmacología , Flavinas/química , Inhibidores de la Monoaminooxidasa/farmacología , Monoaminooxidasa/efectos de los fármacos , Animales , Bovinos , Cromatografía Liquida/métodos , Ciclopropanos/química , Espectrometría de Masa por Ionización de Electrospray/métodosRESUMEN
1-Phenylcyclopropylamine (1-PCPA) is shown to be an inactivator of the fungal flavoenzyme monoamine oxidase (MAO) N. Inactivation results in an increase in absorbance at 410 nm and is accompanied by the concomitant loss of the flavin absorption band at 458 nm. The spectral properties of the covalent adduct formed between the flavin cofactor of MAO N and 1-PCPA are similar to those reported for the irreversible inactivation product formed with 1-PCPA and mammalian mitochondrial monoamine oxidase B [Silverman, R. B., and Zieske, P. A. (1985) Biochemistry 24, 2128-2138]. There is a hypsochromic shift of the 410 nm band upon lowering the pH to 2, indicating that an N(5)-flavin adduct formed upon inactivation. Use of the fungal enzyme, MAO N, which lacks the covalent attachment to the flavin adenine dinucleotide (FAD) cofactor present in the mammalian forms MAO A and MAO B, has allowed for the isolation and further structural identification of the flavin-inactivator adduct. The incorporation of two (13)C labels into the inactivator, [2,3-(13)C(2)]-1-PCPA, followed by analysis using on-line liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy, provided a means to explore the structure of the flavin-inactivator adduct of MAO N. The spectral evidence supports covalent attachment of the 1-PCPA inactivator to the cofactor as N(5)-3-oxo-3-phenylpropyl-FAD.
Asunto(s)
Ciclopropanos/química , Flavinas/química , Inhibidores de la Monoaminooxidasa/química , Monoaminooxidasa/química , Aspergillus niger/enzimología , Cromatografía Líquida de Alta Presión , Cromatografía Liquida , Ciclopropanos/metabolismo , Mononucleótido de Flavina/química , Mononucleótido de Flavina/metabolismo , Flavina-Adenina Dinucleótido/química , Flavina-Adenina Dinucleótido/metabolismo , Flavinas/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Monoaminooxidasa/metabolismo , Inhibidores de la Monoaminooxidasa/metabolismo , Resonancia Magnética Nuclear Biomolecular , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría UltravioletaRESUMEN
BACKGROUND: Monitoring oesophageal pH conventionally detects "acid reflux" (pH less than 4). The pH of the gastric contents determines whether or not reflux can be detected. AIM: To monitor gastric and oesophageal pH simultaneously in order to determine the effect of milk feeds on gastric pH and how this would influence interpretation of the oesophageal pH record. METHODS: Milk fed infants for whom oesophageal pH monitoring was requested underwent simultaneous gastric and oesophageal pH monitoring using a dual channel pH probe. RESULTS: Twenty of 24 records were technically satisfactory. Mean reflux index was 1.0%, range 0.0-4.0%. Gastric pH was less than 4 for 24.5% (range 0.6-69.1%) of the total time. The average time the gastric pH was greater than 4 after feeds was 130 minutes (range 29-212 minutes). The corrected reflux index (limited to the time the gastric pH was less than 4) was 2.6% (range 0.0-11.0%). CONCLUSION: The pH of the gastric contents may be greater than 4 for prolonged intervals, during which oesophageal pH monitoring using current criteria cannot detect reflux nor correlate it with clinical events. A low reflux index may reflect prolonged buffering of gastric acidity rather than the absence of reflux.
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Esófago/química , Reflujo Gastroesofágico/diagnóstico , Alimentos Infantiles , Leche , Estómago/química , Animales , Femenino , Humanos , Concentración de Iones de Hidrógeno , Lactante , Recién Nacido , Masculino , Valor Predictivo de las Pruebas , Factores de TiempoRESUMEN
The oversummer survival of Colletotrichum gloeosporioides in strawberry crown tissue under field conditions was investigated in 1998 and 1999. Strawberry crowns infected naturally with C. gloeosporioides were placed inside cloth bags containing field soil, buried in the field at 5 or 13 cm, then recovered over 6 months of each year. The recovered crowns were plated onto a Colletotrichum spp. semiselective medium and speciated by colony, spore morphology, and molecular markers with species-specific DNA primers. Pathogenicity of selected isolates was confirmed by greenhouse bioassays on strawberry. Of the 428 isolates of Colletotrichum spp. recovered from buried crowns, 96% were C. gloeosporioides and 4% Colletotrichum acutatum. Following an initial increase in the detection of the fungus, survival of C. gloeosporioides was stable for 2 to 3 weeks, then declined. No Colletotrichum spp. were detected after burial for 56 days in 1998 and 98 days in 1999. Because the time between crop seasons is typically more than 170 days, these data support the hypothesis that inoculum of C. gloeosporioides does not survive in buried plant debris between seasons in Florida and, therefore, oversummering crop debris does not contribute inoculum for epidemics of Colletotrichum crown rot in Florida.
RESUMEN
Homopolymers or peptides containing a high percentage of cationic amino acids have been shown to have a unique ability to cross the plasma membrane of cells, and consequently have been used to facilitate the uptake of a variety of biopolymers and small molecules. To investigate whether the polycationic character of these molecules, or some other structural feature, was the molecular basis for the effect, the ability of a variety of homopolymers to enter cells was assayed by confocal microscopy and flow cytometry. Polymers of L- or D-arginine containing six or more amino acids entered cells far more effectively than polymers of equal length composed of lysine, ornithine and histidine. Peptides of fewer than six amino acids were ineffective. The length of the arginine side-chain could be varied without significant loss of activity. These data combined with the inability of polymers of citrulline to enter cells demonstrated that the guanidine headgroup of arginine was the critical structural component responsible for the biological activity. Cellular uptake could be inhibited by preincubation of the cells with sodium azide, but not by low temperature (3 degrees C), indicating that the process was energy dependent, but did not involve endocytosis.
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Permeabilidad de la Membrana Celular , Péptidos/química , Péptidos/metabolismo , Poliaminas/metabolismo , Transporte Biológico/efectos de los fármacos , Biopolímeros/química , Biopolímeros/metabolismo , Permeabilidad de la Membrana Celular/efectos de los fármacos , Citrulina/metabolismo , Citosol/metabolismo , Endocitosis/efectos de los fármacos , Citometría de Flujo , Histidina/metabolismo , Humanos , Células Jurkat , Lisina/metabolismo , Microscopía Confocal , Peso Molecular , Ornitina/metabolismo , Poliaminas/química , Polielectrolitos , Azida Sódica/farmacología , Temperatura , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Certain proteins contain subunits that enable their active translocation across the plasma membrane into cells. In the specific case of HIV-1, this subunit is the basic domain Tat(49-57) (RKKRRQRRR). To establish the optimal structural requirements for this translocation process, and thereby to develop improved molecular transporters that could deliver agents into cells, a series of analogues of Tat(49-57) were prepared and their cellular uptake into Jurkat cells was determined by flow cytometry. All truncated and alanine-substituted analogues exhibited diminished cellular uptake, suggesting that the cationic residues of Tat(49-57) play a principal role in its uptake. Charge alone, however, is insufficient for transport as oligomers of several cationic amino acids (histidine, lysine, and ornithine) are less effective than Tat(49-57) in cellular uptake. In contrast, a 9-mer of l-arginine (R9) was 20-fold more efficient than Tat(49-57) at cellular uptake as determined by Michaelis-Menton kinetic analysis. The d-arginine oligomer (r9) exhibited an even greater uptake rate enhancement (>100-fold). Collectively, these studies suggest that the guanidinium groups of Tat(49-57) play a greater role in facilitating cellular uptake than either charge or backbone structure. Based on this analysis, we designed and synthesized a class of polyguanidine peptoid derivatives. Remarkably, the subset of peptoid analogues containing a six-methylene spacer between the guanidine head group and backbone (N-hxg), exhibited significantly enhanced cellular uptake compared to Tat(49-57) and even to r9. Overall, a transporter has been developed that is superior to Tat(49-57), protease resistant, and more readily and economically prepared.
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Proteínas Portadoras/química , Productos del Gen tat/química , Péptidos/química , Péptidos/farmacocinética , Secuencia de Aminoácidos , Animales , Linfocitos B/metabolismo , Transporte Biológico , Proteínas Portadoras/síntesis química , Proteínas Portadoras/metabolismo , Células Cultivadas , Diseño de Fármacos , Productos del Gen tat/metabolismo , VIH-1/metabolismo , Humanos , Células Jurkat , Cinética , Linfocitos/metabolismo , Ratones , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Péptidos/síntesis química , Peptoides , Subunidades de Proteína , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
The objective of this study was to investigate whether leukocytes could be recruited by rolling leukocytes in a human whole blood model system. In all experiments, either neutrophils, whole blood, or diluted blood was perfused over immobilized E-selectin. With isolated neutrophils (2 x 10(5)/mL), the free-flowing neutrophils were captured by attached neutrophils to form secondary interactions that resulted in lines of rolling leukocytes. These secondary tethers accounted for 50% to 60% of all interactions and were eliminated by an L-selectin antibody, which also eliminated the lines of rolling leukocytes. Perfusion of whole blood or diluted blood revealed no lines of rolling leukocytes. The addition of red blood cells to isolated neutrophils either in a 1000:1 or a 10:1 ratio also inhibited lines of rolling leukocytes. Leukocytes were fluorescently labeled with rhodamine-6G so that leukocyte-leukocyte interactions could be studied in whole blood. A small number of secondary tethers (less than 20%) occurred and could be reduced by more than 80% with an L-selectin antibody. However, the overall impact on leukocyte recruitment was negligible. Similar experiments were performed using murine whole blood or isolated murine leukocytes. In the absence of red blood cells, murine leukocytes also formed lines of rolling leukocytes on E-selectin, and secondary tethers accounted for 50% of total interactions. However, when murine blood (diluted 1:5 with buffer) was perfused over E-selectin, secondary tethers accounted for only 13% of total interactions. These interactions were completely absent when blood was used from L-selectin-deficient mice. These data demonstrate for the first time that the importance of L-selectin-dependent leukocyte-leukocyte interactions is greatly reduced in whole blood and does not enhance overall recruitment of leukocytes in this physiologic milieu. (Blood. 2000;95:2954-2959)
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Adhesión Celular/fisiología , Selectina L/fisiología , Leucocitos/fisiología , Neutrófilos/fisiología , Animales , Comunicación Celular , Humanos , Técnicas In Vitro , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Ten species of Pythium and a group of isolates that produced filamentous sporangia but did not form sexual structures (Pythium 'group F') were recovered from the root systems of fresh market bell pepper plants grown on polyethylene-mulched production systems in Florida. Pathogenicity tests using pasteurized field soil inoculated with infested wheat seed demonstrated that P. aphanidermatum, P. myriotylum, P. helicoides, and P. splendens can cause significant root rot and reductions in root growth of pepper. P. aphanidermatum and P. myriotylum caused the most severe root rot, the greatest reductions in plant weight, and 42 and 62% plant mortality, respectively. In pathogenicity tests with tomato plants, these four species produced similar plant weight losses and disease ratings to those observed in pepper, but little or no plant mortality. Low incidences of root tip necrosis in pepper plants were observed with P. arrhenomanes, P. catenulatum, P. graminicola, and P. irregulare, but none of these species caused losses in root weight and only P. irregulare reduced shoot weight. P. periplocum, P. spinosum, and Pythium sp. F colonized root tissue of pepper but caused no significant root rot and did not adversely affect growth. Similar trends were observed with tomato, except that P. arrhenomanes caused limited root tip necrosis without affecting plant growth and P. catenulatum, P. graminicola, P. irregulare, P. spinosum, and Pythium sp. F colonized at least some of the plants but did not cause root disease. A significant interaction between temperature and P. aphanidermatum or P. myriotylum was observed on pepper transplants. The greatest reductions in growth occurred at 28°C, whereas plant mortality only occurred at 34°C.
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ABSTRACT Phytophthora nicotianae was added to pasteurized soil at the rate of 500 laboratory-produced chlamydospores per gram of soil and exposed to temperatures ranging from 35 to 53 degrees C for 20 days. The time required to reduce soil populations to residual levels (0.2 propagule per gram of soil or less) decreased with increasing temperatures. Addition of cabbage residue to the soil reduced the time required to inactivate chlamydospores. Temperature regimes were established to simulate daily temperature changes observed in the field, with a high temperature of 47 degrees C for 3 h/day, and were good estimators of the efficacy of soil solarization for the control of P. nicotianae in soil. Cabbage amendment reduced the time required to inactivate chlamydospores of P. nicotianae and its effect was more pronounced at lower temperature regimes.
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Filtrates from nematode-parasitic fungi have been reported to be toxic to plant-parasitic nematodes. Our objective was to determine the effects of fungal filtrates on second-stage juveniles and eggs of Heterodera glycines. Eleven fungal species that were isolated from cysts extracted from a soybean field in Florida were tested on J2, and five species were tested on eggs in vitro. Each fungal species was grown in Czapek-Dox broth and malt extract broth. No toxic activity was observed for fungi grown in Czapek-Dox broth. Filtrates from Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, and Fusarium solani grown in malt extract broth were toxic to J2, whereas filtrates from Exophiala pisciphila, Fusarium oxysporum, Gliocladium catenulatum, Pyrenochaeta terrestris, Verticillium chlamydosporium, and sterile fungi 1 and 2 were not toxic to J2. Filtrates of P. lilacinus, S. heteroderae, and N. vasinfecta grown in malt extract broth reduced egg viability, whereas F. oxysporum and P. terrestris filtrates had no effect on egg viability.
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Unlike the ability to acquire our native language, we struggle to learn multiplication and division. It may then come as a surprise that the mental machinery for performing lightning-fast integer arithmetic calculations could be within us all even though it cannot be readily accessed, nor do we have any idea of its primary function. We are led to this provocative hypothesis by analysing the extraordinary skills of autistic savants. In our view such individuals have privileged access to lower levels of information not normally available through introspection.
Asunto(s)
Matemática , Procesos Mentales/fisiología , Arte , Trastorno Autístico/psicología , Niño , Preescolar , Humanos , Aprendizaje/fisiología , Modelos Psicológicos , Música , Discriminación de la Altura Tonal/fisiologíaRESUMEN
Usually we rely on vaccination to promote an immune response to a pathogenic microbe. In this study, we demonstrate a suppressive from of vaccination, with DNA encoding a minigene for residues 139-151 of myelin proteolipid protein (PLP139-151), a pathogenic self-Ag. This suppressive vaccination attenuates a prototypic autoimmune disease, experimental autoimmune encephalomyelitis, which presents clinically with paralysis. Proliferative responses and production of the Th1 cytokines, IL-2 and IFN-gamma, were reduced in T cells responsive to PLP139-151. In the brains of mice that were successfully vaccinated, mRNA for IL-2, IL-15, and IFN-gamma were reduced. A mechanism underlying the reduction in severity and incidence of paralytic autoimmune disease and the reduction in Th1 cytokines involves altered costimulation of T cells; loading of APCs with DNA encoding PLP139-151 reduced the capacity of a T cell line reactive to PLP139-151 to proliferate even in the presence of exogenous CD28 costimulation. DNA immunization with the myelin minigene for PLP-altered expression of B7.1 (CD80), and B7.2 (CD86) on APCs in the spleen. Suppressive immunization against self-Ags encoded by DNA may be exploited to treat autoimmune diseases.
Asunto(s)
Autoantígenos/genética , Autoantígenos/inmunología , Encefalomielitis Autoinmune Experimental/inmunología , Encefalomielitis Autoinmune Experimental/prevención & control , Inmunosupresores/inmunología , Activación de Linfocitos , Linfocitos T/inmunología , Vacunas de ADN/inmunología , Animales , Autoantígenos/administración & dosificación , Secuencia de Bases , Encefalomielitis Autoinmune Experimental/etiología , Femenino , Inmunosupresores/administración & dosificación , Inyecciones Intramusculares , Activación de Linfocitos/genética , Ratones , Ratones Endogámicos , Datos de Secuencia Molecular , Proteína Proteolipídica de la Mielina/administración & dosificación , Proteína Proteolipídica de la Mielina/genética , Proteína Proteolipídica de la Mielina/inmunología , Fragmentos de Péptidos/administración & dosificación , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/inmunología , Células TH1/inmunología , Vacunas de ADN/administración & dosificaciónRESUMEN
The effects of soil solarization with or without cabbage leaf amendments on the survival of Phytophthora spp. were evaluated in several North Florida soils. Soil temperature under solarization treatments reached a maximum of 47°C at a 10-cm depth, but only 41°C at 25 cm. Solarization with a clear, gas-impermeable film was as effective as methyl bromide in reducing populations of P. nicotianae at a 10-cm depth but had no effect on populations at a depth of 25 cm. Populations of P. capsici after solarization with either a clear, low-density polyethylene or a clear, gas-impermeable film were similar to methyl bromide treatment at the 10-cm depth, while at the 25-cm depth, no reduction in populations was observed. Incorporation of cabbage into the soil at a rate of 6.6 to 8.9 kg/m2 did not enhance the effectiveness of solarization in reducing populations of either Phytophthora sp.