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1.
Med Oral Patol Oral Cir Bucal ; 22(5): e630-e635, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28809376

RESUMO

OBJECTIVES: Injury of the inferior alveolar nerve (IAN) is a serious intraoperative complication that may occur during routine surgical procedures, such as dental implant placement or extraction of impacted teeth. Thus, the purpose of this study was to analyze the trajectory of the mandibular canal (MC), the location of the mental foramen (MF) and the presence and extension of an anterior loop of the mental nerve (AL). STUDY DESIGN: In this cross-sectional study, a total of 348 CBCTs were analyzed. Distances from MC to the surface of the basal, medial and lateral cortical of the mandible were measured at the level of the second molar, first molar and second premolar. Location of the MF relative to the apices of the premolars, as well as incidence and anterior extent of the AL were also determined. RESULTS: Significant and clinically relevant correlations were found between the position of the MC in women, which was located more caudal (r=-0.219, p=0.007; r=-0.276, p<0.001; right and left, respectively) and lateral (r=-0.274, p=0.001; r=-0.285, p<0.001; right and left, respectively), particularly at the level of the premolars. Additionally, the presence (r=-0.181, p=0.001; r=-0.163, p=0.002; right and left, respectively) and anterior extension (r=-0.180, p=0.009; r=-0.285, p=0.05; right and left, respectively) of the AL was found to be inversely correlated with the age of the patient. CONCLUSIONS: This analysis of a Caucasian population has found that the older the patient, the lower the incidence of the loop and the shorter its anterior extension.


Assuntos
Nervo Mandibular/anatomia & histologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Queixo , Tomografia Computadorizada de Feixe Cônico , Estudos Transversais , Feminino , Humanos , Masculino , Nervo Mandibular/diagnóstico por imagem , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
2.
Appl Microbiol Biotechnol ; 97(8): 3373-81, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23188458

RESUMO

Spodoptera exigua Se301 cells have been successfully adapted to two different commercial serum-free media (SFM; Ex-Cell 420 and Serum-Free Insect Medium-1) by gradually reducing the 10 %-added serum-containing medium content from 100 % to 0 % (v/v) in suspended cultures. Both direct adaptation to a serum-free medium and cell growth in the absence of protective additives against fluid dynamic stress [polyvinyl pyrrolidone and polyvinyl alcohol] and disaggregation [dextran sulfate] proved impossible. Cells grew reproducibly in both SFMs once the serum had been completely removed, although the use of Ex-Cell 420 resulted in higher growth rates and cell densities. Turbulence was sufficiently high to reduce growth rates and final cell densities at the highest Reynolds number investigated, although no clear influence of agitation was observed on virus productivity. Both attached and suspended Se301 cell cultures were successfully infected with the SeMNPV baculovirus. Cells adapted to different conditions (attached or suspended culture, serum-containing or serum-free medium) showed different occlusion bodies productivities at the two multiplicities of infection assayed (0.1 and 0.5).


Assuntos
Baculoviridae/crescimento & desenvolvimento , Técnicas de Cultura de Células/métodos , Vetores Genéticos , Animais , Linhagem Celular , Meios de Cultura Livres de Soro , Spodoptera
3.
Int J Clin Health Psychol ; 22(3): 100318, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35847567

RESUMO

Background: Although there is broad agreement that perceived risks determine risk-taking behavior, previous research has shown that this association may not be as straightforward as expected. The main objective of this study was to investigate if the levels of impulsivity can explain part of these controversial findings. Method: A total of 1579 participants (Mage = 23.06, from 18 to 60 years; 69.4% women) were assessed for levels of risk perception, risk-taking avoidance, and impulsivity. Results: The results showed that while impulsivity was significantly and negatively related to both risk perception and risk-taking avoidance, the relationship with risk-taking avoidance was significantly stronger than with risk perception. The levels of impulsivity predicted risk-taking avoidance even when controlling for risk perception. Conclusions: These findings indicate that impulsivity can differentially affect risk perception and risk-taking. We propose that the stronger influence of impulsivity on risk-taking is due to the greater reliance of risk-taking, compared with risk perception, on automatic processes guided by impulses and emotions.

4.
Sci Rep ; 10(1): 12469, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32719329

RESUMO

Recent studies investigated the association of cardiorespiratory fitness with white matter microstructure in children, yet little work has explored to what extent other components of physical fitness (i.e., muscular or motor fitness) are associated with white matter microstructure. Indeed, this association has not been previously explored in children with overweight/obesity who present a different white matter development. Therefore, we aimed to examine associations between physical fitness components and white matter microstructure in children with overweight/obesity. In total, 104 (10.04 ± 1.15 years old; 43 girls) children were included in this cross-sectional study. Physical fitness was assessed using the ALPHA-fitness test battery. Fractional anisotropy (FA) and mean diffusivity were derived from diffusion tensor imaging (DTI). No association was found between physical fitness and global DTI metrics (all P > 0.082). Within individual tracts, all associations became non-significant when analyses were adjusted for multiple comparisons. Using the voxel-wise approach, we identified a small cluster in the left lateral frontal lobe where children with greater upper-body muscular fitness showed higher FA (PFWE-corrected = 0.042). Although our results cannot conclude physical fitness is related to white matter microstructure in children with overweight/obesity; those findings indicate that the association of muscular fitness with white matter microstructure might be more focal on frontal areas of the brain, as opposed to global differences.


Assuntos
Obesidade/diagnóstico por imagem , Sobrepeso/diagnóstico por imagem , Aptidão Física , Substância Branca/diagnóstico por imagem , Anisotropia , Criança , Estudos Transversais , Imagem de Tensor de Difusão , Feminino , Humanos , Masculino , Força Muscular , Obesidade/fisiopatologia , Sobrepeso/fisiopatologia , Substância Branca/anatomia & histologia
5.
Neuropsychologia ; 119: 464-473, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30244003

RESUMO

We are often required to make decisions that can have safe or risky consequences. Evaluating the risk of each possible alternative is an important step before making our final decision. The main goal of the present research was to explore the neural basis of risk perception in a naturalistic context (driving). Twenty-two drivers evaluated the perceived risk in 72 traffic situations (previously categorized by driving instructors) while brain activity was recorded using fMRI. A neural network involving attentional factors, emotional processing, stimulus-response associations, and risk aversion was related to the perception of risks. Given the nature of our task, a more prominent role was played by emotional factors (evaluation of the consequences) than cognitive factors (e.g. probabilistic calculations). Moreover, activation in the insula, inferior frontal gyrus, precentral/postcentral gyrus, inferior parietal gyrus, and temporal and occipital regions linearly increased as a function of risk level. Our findings provide a new step towards understanding the neural processing underlying risk behavior in daily life tasks, which is particularly relevant given the study context and its important practical implications for our society.


Assuntos
Condução de Veículo , Encéfalo/fisiologia , Percepção/fisiologia , Assunção de Riscos , Associação , Atenção/fisiologia , Condução de Veículo/psicologia , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Emoções/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Adulto Jovem
6.
Brain Imaging Behav ; 12(3): 653-662, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28447245

RESUMO

Complex tasks require the learning and integration of multiple cognitive, sensory, and psychomotor skills for correct execution. Driving-related skills are developed step by step through the increase of mileage driven and the accumulation of practice in different traffic situations. The acquisition of these skills should be reflected in the brain structure. However, no previous studies have explored brain structural variations associated with driving experience. The aim of the present study was to investigate whether driving frequency, defined as average annual driving mileage, is related to neuroanatomical variations in gray matter (GM) volume and white matter (WM) integrity using voxel-based morphometry (VBM) and DTI-based fractional anisotropy (FA), respectively. We recruited 83 drivers with variable range of annual driving mileage and controlled for age, sex, handedness, IQ, time since the acquisition of driving license, use of motorcycles/mopeds and bicycles, perceived driving skills, and subjective probability of having an accident. Our results showed variations in white matter FA as a function of mileage driven. Driving experience was related to a significant increase of FA in parts of the right hemisphere superior and inferior longitudinal fasciculus, anterior thalamic radiation, forceps majors, inferior fronto-occipital fasciculus, and corticospinal tract. No significant differences were observed in gray matter volumes. FA variations were found in brain regions that have been associated with cognitive, visual, and motor processes necessary for skilled performance in driving. These results suggest that variations in white matter diffusivity can underlie the development of driving skills and safer driving.


Assuntos
Condução de Veículo , Encéfalo/diagnóstico por imagem , Prática Psicológica , Adulto , Encéfalo/anatomia & histologia , Imagem de Tensor de Difusão , Feminino , Substância Cinzenta/anatomia & histologia , Substância Cinzenta/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão , Substância Branca/anatomia & histologia , Substância Branca/diagnóstico por imagem , Adulto Jovem
7.
J Sci Med Sport ; 21(2): 179-184, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29031643

RESUMO

OBJECTIVES: To examine the associations of physical fitness (i.e. cardiorespiratory fitness, muscular strength, and speed/agility) with psychological distress and psychological well-being in overweight/obese pre-adolescent children. DESIGN: 110 overweight/obese children (10.0±1.1years old, 61 boys) from the ActiveBrains project (http://profith.ugr.es/activebrains) participated in this cross-sectional study. METHODS: Physical fitness was evaluated by the ALPHA battery test. Cardiorespiratory fitness was additionally evaluated by a maximal incremental treadmill. Stress was assessed by the Children's Daily Stress Inventory, anxiety by the State-Trait Anxiety Inventory, depression by the Children Depression Inventory, positive affect and negative affect by the Positive and Negative Affect Scale for Children, happiness by the Subjective Happiness Scale, optimism by the Life Orientation Test, and self-esteem by the Rosenberg Self-Esteem questionnaire. Linear regression adjusted for sex and peak height velocity was used to examine associations. RESULTS: Absolute upper-body muscular strength was negatively associated with stress and negative affect (ß=-0.246, p=0.047; ß=-0.329, p=0.010, respectively). Furthermore, absolute lower-body muscular strength was negatively associated with negative affect (ß=-0.301, p=0.029). Cardiorespiratory fitness, expressed by the last completed lap, and relative upper-body muscular strength were positively associated with optimism (ß=0.220, p=0.042; ß=0.240, p=0.017, respectively). Finally, absolute upper-body muscular strength was positively associated with self-esteem (ß=0.362, p=0.003) independently of sex and weight status (p for interactions >0.3), and absolute lower-body muscular strength was also positively associated with self-esteem (ß=0.352, p=0.008). CONCLUSIONS: Muscular strength was associated with psychological distress (i.e. stress and negative affect) and psychological well-being (i.e. optimism and self-esteem) as well as cardiorespiratory fitness was associated with optimism. Therefore, increased levels of physical fitness, specifically muscular strength, could have significant benefits for overweight/obese children psychological health.


Assuntos
Afeto , Aptidão Cardiorrespiratória/psicologia , Força Muscular/fisiologia , Sobrepeso/psicologia , Obesidade Infantil/psicologia , Criança , Estudos Transversais , Depressão/etiologia , Teste de Esforço , Feminino , Humanos , Modelos Lineares , Masculino , Autoimagem , Estresse Psicológico/etiologia , Inquéritos e Questionários
8.
J Dent Res ; 95(4): 372-9, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26701350

RESUMO

At the present time, peri-implantitis has become a global burden that occurs with a frequency from 1% to 47% at implant level. Therefore, we aimed herein at assessing the impact of peri-implant maintenance therapy (PIMT) on the prevention of peri-implant diseases. Electronic and manual literature searches were conducted by 3 independent reviewers using several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register, for articles up to June 2015 without language restriction. Articles were included if they were clinical trials aimed at demonstrating the incidence of peri-implant diseases under a strict regime or not of PIMT. Implant survival and failure rate were studied as secondary outcomes. A meta-analysis was conducted to evaluate the influence of PIMT and other reported variables upon peri-implant diseases. Thirteen and 10 clinical trials were included in the qualitative and quantitative analysis, respectively. Mucositis was affected by history of periodontitis and mean PIMT at implant and patient levels, respectively. Similarly, significant effects of history of periodontal disease were obtained for peri-implantitis for both implant and patient levels. Furthermore, mean PIMT interval was demonstrated to influence the incidence of peri-implantitis at implant but not patient level. PIMT interval showed significance at both levels. For implant survival, implants under PIMT have 0.958 the incident event than those with no PIMT. Within the limitations of the present systematic review, it can be concluded that implant therapy must not be limited to the placement and restoration of dental implants but to the implementation of PIMT to potentially prevent biologic complications and hence to heighten the long-term success rate. Although it must be tailored to a patient's risk profiling, our findings suggest reason to claim a minimum recall PIMT interval of 5 to 6 mo. Additionally, it must be stressed that even in the establishment of PIMT, biologic complications might occur. Thus, patient-, clinical-, and implant-related factors must be thoroughly explored.


Assuntos
Implantes Dentários/efeitos adversos , Mucosite/prevenção & controle , Peri-Implantite/prevenção & controle , Falha de Restauração Dentária , Humanos , Incidência , Mucosite/epidemiologia , Peri-Implantite/epidemiologia , Doenças Periodontais/complicações , Fatores de Risco
9.
J Exp Psychol Hum Percept Perform ; 24(2): 664-72, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9554102

RESUMO

In 5 experiments the authors examine the role of object-based grouping on negative priming. The experiments used a letter-matching task with multiple letters presented in temporally separated prime and probe displays. On mismatch trials, distractor letters in primes were repeated as targets in probes, or distractor and target letters were completely different. Negative priming was shown by slowed responses when distractors were repeated as targets relative to when the stimuli differed. This occurred both when only letters were presented (Experiments 1 and 4) and when letters were surrounded by boxes (Experiment 5). Experiments 2, 3, and 4 showed that negative priming was affected by the grouping of target and distractor letters in prime displays. Negative priming was reduced when 1 of the distractor letters was placed in the target box and 1 was left outside the box; facilitatory priming was observed when both distractor letters appeared in the target box. The data were accounted for in terms of there being (a) object-based competition for visual selection, (b) inhibition of distractor objects that compete for selection with target objects, and (c) activation or inhibition of the identities of all component elements within target or distractor objects.


Assuntos
Aprendizagem por Associação , Atenção , Aprendizagem por Discriminação , Reconhecimento Visual de Modelos , Adulto , Feminino , Humanos , Masculino , Desempenho Psicomotor , Psicofísica , Estudantes/psicologia
10.
JPEN J Parenter Enteral Nutr ; 2(1): 28-30, 1978.
Artigo em Inglês | MEDLINE | ID: mdl-121808

RESUMO

The use of a standardized hyperalimentation solution that can be modified is discussed. A comparison of in-hospital addition of electrolytes with factor addition of electrolytes is presented, in which both solutions are acceptable to patients and in which the labor and cost to the pharmacy are decreased in the factory-mixed additives.


Assuntos
Eletrólitos , Nutrição Parenteral Total/métodos , Nutrição Parenteral/métodos , Serviço de Farmácia Hospitalar , Aminoácidos , Contagem de Células Sanguíneas , Glicemia/análise , Glucose , Hospitais com mais de 500 Leitos , Humanos , New Jersey , Nutrição Parenteral Total/economia , Equilíbrio Hidroeletrolítico
11.
Arch Clin Neuropsychol ; 5(3): 231-41, 1990.
Artigo em Inglês | MEDLINE | ID: mdl-14589683

RESUMO

The present research was designed to assess auditory discrimination, attention, memory, and learning in paranoid schizophrenic patients using a dichotic listening procedure consisting of attending to a signal or a story channeled only to one ear. A sample of 24 paranoid schizophrenics and 24 normal controls volunteered. In Experiment 1, 12 schizophrenics and 12 controls attended to the signal while shadowing the story. The task of the other 12 clinical and 12 normal subjects in Experiment 2 was identical to Experiment 1 with the exception that the subjects did not shadow the story. In each experiment, subjects completed three trials as well as three evaluations of the story. The results indicated that schizophrenics showed substantial attentional deficits in comparison to normal controls.

12.
Carbohydr Polym ; 114: 141-148, 2014 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-25263874

RESUMO

Injectable polymer scaffolds are particularly attractive for guided tissue growth and drug/cell delivery with minimally invasive intervention. In the present work, "all-polymeric" gelling systems based on pectins and water-soluble maltose-conjugated chitosans (CM) have been developed. Maltose-conjugated chitosan has been synthesized at three different molar ratios, as evaluated by FITR analysis and fluorimetric titration. A thorough rheological characterization of the blends and their parent solutions has been performed. Macroscopic gelation has been achieved by mixing the high esterification degree pectins with CM at higher maltose grafted to chitosan contents. Gels form in a few minutes and reach their full strength in less than two hours. These features encourage their further development as scaffold for tissue engineering.


Assuntos
Quitosana/química , Géis/química , Maltose/química , Pectinas/química , Quitosana/análise , Géis/análise , Concentração de Íons de Hidrogênio , Maltose/análise , Pectinas/análise , Soluções/análise , Soluções/química , Alicerces Teciduais/química
13.
J Dent Res ; 93(7 Suppl): 80S-85S, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24621670

RESUMO

In this study, we analyzed the influence of prosthetic abutment height on marginal bone loss (MBL) around implants in the posterior maxilla. In this retrospective cohort study, the radiographically determined MBL was related to the height of the abutments of internal conical connection implants at 6 and 18 months post-loading. Data were gathered on age, sex, bone substratum, smoking habit, history of periodontitis, and prosthetic features, among other variables. A linear mixed model was used for statistical analysis. The study included 131 patients receiving 315 implants. MBL rates at 6 and 18 months were mainly affected by the abutment height but were also significantly influenced by the bone substratum, periodontitis, and smoking habit. MBL rates were higher for prosthetic abutment < 2 mm vs. ≥ 2 mm, for periodontal vs. non-periodontal patients, for grafted vs. pristine bone, and for a heavier smoking habit. The abutment height is a key factor in MBL. MBL rates followed a non-linear trend, with a greater MBL rate during the first 6 months post-loading than during the next 12 months.


Assuntos
Dente Suporte , Projeto do Implante Dentário-Pivô , Peri-Implantite/etiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea/fisiologia , Transplante Ósseo/métodos , Estudos de Coortes , Prótese Dentária Fixada por Implante , Feminino , Seguimentos , Humanos , Masculino , Maxila/cirurgia , Pessoa de Meia-Idade , Perda da Inserção Periodontal/classificação , Periodontite/classificação , Radiografia Panorâmica , Estudos Retrospectivos , Fumar , Propriedades de Superfície , Adulto Jovem
14.
J Dent Res ; 93(10): 993-8, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25139359

RESUMO

Cardiovascular disease has been associated with 40% of deaths in high-income countries and 28% in lower-income countries. The relationship between periodontitis and acute myocardial infarction is well documented, but it has not been established whether the extent and severity of periodontitis influence the infarct size. This cross-sectional and analytic study was designed to investigate the association of chronic periodontitis extent and severity with acute myocardial infarct size as indicated by serum cardiac troponin I and myoglobin levels. Sociodemographic, periodontal, cardiologic, and hematologic variables were gathered in 112 consecutive patients with myocardial infarction. The extent (Arbes Index) and severity (Periodontal Inflammatory Severity Index) of the chronic periodontitis were significantly associated with troponin I levels after controlling for sociodemographic and clinical confounders (change in R (2) = .041, p < .02, and R (2) = .031, p = .04). However, only the extent index accounted for levels of myoglobin (change in R (2) = .030, p < .05), total leukocytes (change in R (2) = .041 p < .02), and neutrophils (change in R (2) = .059, p < .01). Mediated regression analysis showed that leukocytes and neutrophils may underlie these observed relationships of chronic periodontitis with troponin I and myoglobin. To our knowledge, this study contributes the first research data demonstrating that the extent and severity of periodontitis is positively associated with acute myocardial infarct size as measured by serum troponin I and myoglobin levels.


Assuntos
Periodontite Crônica/classificação , Infarto do Miocárdio/classificação , Periodontite Crônica/sangue , Angiografia Coronária , Estudos Transversais , Complicações do Diabetes/classificação , Escolaridade , Eletrocardiografia , Feminino , Seguimentos , Humanos , Contagem de Leucócitos , Masculino , Estado Civil , Pessoa de Meia-Idade , Infarto do Miocárdio/sangue , Mioglobina/sangue , Neutrófilos/patologia , Perda da Inserção Periodontal/classificação , Índice Periodontal , Bolsa Periodontal/classificação , Fatores Sexuais , Método Simples-Cego , Troponina I/sangue
15.
Rev Clin Esp (Barc) ; 214(3): 113-20, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24560733

RESUMO

BACKGROUND AND OBJECTIVES: Whilst traditional studies have shown that obese individuals are at a higher risk of cardiovascular events compared to lean subjects, recent studies in patients with acute myocardial infarction (AMI) have suggested that obesity may exert protective effects (the "obesity paradox"). We sought to assess the relationship between body mass index (BMI) and the BARI score (BARIsc), a validated tool used to assess myocardium at risk, in patients with acute coronary syndrome. PATIENTS AND METHODS: Participants were 116 consecutive patients (mean age, 60.6 years; 97 men) with AMI (68 ST elevated myocardial infarction, STEMI; 48 non-ST elevated myocardial infarction, NSTEMI). Demographics, BMI, risk factors, biochemistry data, left ventricular function, angiographic data and the BARIsc were assessed in every patient. RESULTS: Multiple linear regression analyses showed that BMI significantly correlated with BARIsc; ß=.23, p<0.02. This was found only in the overweight/obese patients, ß=.27, p<0.01, but not in patients with normal BMIs, ß=0.08, p=0.71. CONCLUSIONS: An increased body weight is associated with an increased area of myocardium at risk in patients with ACS.


Assuntos
Síndrome Coronariana Aguda/epidemiologia , Miocárdio/patologia , Obesidade/epidemiologia , Sobrepeso/epidemiologia , Síndrome Coronariana Aguda/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Estudos Transversais , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Fatores de Risco
16.
Conscious Cogn ; 14(2): 278-95, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15950882

RESUMO

A classical definition of automaticity establishes that automatic processing occurs without attention or consciousness, and cannot be controlled. Previous studies have demonstrated that semantic priming can be reduced if attention is directed to a low-level of analysis. This finding suggests that semantic processing is not automatic since it can be controlled. In this paper, we present two experiments that demonstrate that semantic processing may occur in the absence of attention and consciousness. A negative semantic priming effect was found when a low-level prime-task was required and when a masked lexical decision prime-task was performed (Experiment 1). This paper also discusses the limitations of the inhibitory mechanism involved in negative semantic priming effect.


Assuntos
Automatismo , Cognição , Mascaramento Perceptivo , Semântica , Adolescente , Adulto , Atenção , Estado de Consciência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tempo de Reação , Vocabulário
17.
J Bacteriol ; 101(2): 476-82, 1970 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-5413822

RESUMO

Anthranilate synthetase from Bacillus alvei was partially purified by ammonium sulfate fractionation and was stabilized by glycerol. The reaction mechanism of the enzyme was found to be sequential with respect to substrate, and the enzyme formed a hydroxamic acid in the absence of Mg(++). The K(m) for chorismic acid was 1.25 x 10(-4)m, and the K(m) for l-glutamine was 5.5 x 10(-4)m. Enzyme activity was inhibited by tryptophan noncompetitively with respect to chorismic acid and uncompetitively with respect to l-glutamine. An analysis of the inhibition patterns indicated that tryptophan may act as a dead end inhibitor and bind at the catalytic site. Enzyme activity could be completely inhibited in vitro and in vivo under the appropriate conditions, and enzyme synthesis was sensitive to repression by tryptophan. A sedimentation coefficient of 5.5S and an estimated molecular weight of 90,000 were obtained for the enzyme.


Assuntos
Bacillus/enzimologia , Transaminases/metabolismo , ortoaminobenzoatos/metabolismo , Centrifugação com Gradiente de Concentração , Cromatografia , Cromatografia em Gel , Meios de Cultura , Ácidos Cicloexanocarboxílicos/metabolismo , Ácidos Cicloexanocarboxílicos/farmacologia , Glutamina/farmacologia , Ácidos Hidroxâmicos/biossíntese , Cinética , Triptofano/farmacologia , ortoaminobenzoatos/análise
18.
J Clin Microbiol ; 11(5): 515-21, 1980 May.
Artigo em Inglês | MEDLINE | ID: mdl-6769956

RESUMO

Antisera against whole cells of each Peptostreptococcus species (P. anaerobius, P. micros, P. parvulus, and P. productus) were produced in rabbits. When these antisera were reacted against sonically disrupted cells and culture supernatant fluids in Ouchterlony tests, lines of identity were obtained among the antigens from all the species and uninoculated culture medium. When the antisera were subsequently absorbed with the dehydrated culture medium used to grow the peptostreptococci, all cross-reactions in heterologous antigen-antibody combinations were eliminated, leaving only species-specific precipitin arcs. These absorbed antisera, specific for each Peptostreptococcus species by Ouchterlony tests, were used for rapid identification studies. Staphylococcus aureus-bearing protein A was sensitized with each absorbed antiserum. These reagents produced specific coagglutination reactions with suspensions of each Peptostreptococcus reference strain and with 16 clinical isolates. No cross-reactions occurred with the Streptococcus intermedius, Peptococcus magnus, or Peptococcus asaccharolyticus strains tested.


Assuntos
Antígenos de Bactérias/análise , Peptostreptococcus/classificação , Testes de Aglutinação/métodos , Reações Cruzadas , Imunodifusão , Peptostreptococcus/imunologia , Staphylococcus aureus
19.
Appl Environ Microbiol ; 50(3): 629-33, 1985 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16346883

RESUMO

An Arthrobacter sp. isolated from a glucose-sucrose agar plate was found to produce a neutral, extremely viscous, opalescent extracellular polymer. Growth, polymer production, and rheological properties and chemical composition of the isolated polymer were examined. The polymer was found to be substantially different from other arthrobacter polymers. Some unusual properties included irreversible loss of viscosity with high temperature and degradation of the polymer during fermentation and upon storage at 4 degrees C. Other characteristics included dependence on sucrose for polymer production, relative pH stability, increased viscosity with increased salt concentration, and pseudoplasticity. The polymer was found to be composed primarily (if not entirely) of d-fructose. The fructose content and other characteristics suggested that the polymer was a levan.

20.
Q J Exp Psychol B ; 45(1): 15-32, 1992 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1496136

RESUMO

In three experiments, successive negative contrast was examined in one-way avoidance learning. Reward magnitude in first (pre-shift) and second (post-shift) phases was manipulated by time spent in the safe compartment. Experiment 1 demonstrated that when time in the danger compartment was held constant, a group shifted from a large reward--30 sec spent in the safe compartment--to a small reward--1 sec--showed poor performance and longer response latency than a group conditioned with the small reward in both phases. Experiment 2 replicated this effect with a less intense shock and also demonstrated that a group shifted from large to small reward performed more poorly than a group exposed to large reward--30 sec--in both phases. Finally, Experiment 3 showed that changes in intertrial interval, defined as total time spent in the safe compartment and the danger compartment before the onset of the warning signal, were not responsible for this contrast effect. These results suggest that time spent in a safe place can act as appetitive incentive during one-way avoidance learning.


Assuntos
Nível de Alerta , Aprendizagem da Esquiva , Condicionamento Clássico , Esquema de Reforço , Meio Social , Animais , Medo , Feminino , Ratos , Ratos Endogâmicos , Tempo de Reação
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