Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 53
Filtrar
1.
Anaesthesia ; 74(2): 203-210, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30467827

RESUMO

Fibreoptic-guided tracheal intubation using a supraglottic airway device as a conduit is a technique that can be used in anticipated and unanticipated difficult airway management. Although the i-gel® supraglottic airway device has been examined for this purpose, the LMA® ProtectorTM , a recently introduced second-generation supraglottic airway device, has not been evaluated for this use in clinical trials. This prospective, randomised clinical trial compared fibreoptic-guided tracheal intubation via i-gel and LMA Protector supraglottic airway devices in two UK hospitals. Patients who were ASA physical status 1 or 2 and undergoing elective surgery requiring tracheal intubation were recruited to the study. A block randomisation list was generated for each study site. The primary outcome measure was time to successful tracheal intubation and secondary outcomes were tracheal intubation success rate, glottic view through flexible fibrescope, ease of tracheal intubation using operator visual analogue score, supraglottic airway device insertion time and insertion success rate. Ninety patients were randomly allocated to each device, and final data analysis was carried out for 92 patients in the i-gel group and 86 patients in the LMA Protector group. Mean (SD) tracheal intubation time in the i-gel and LMA Protector groups were 54.3 (13.8) s and 52.0 (13.0) s, respectively (p = 0.240). There were no significant differences in tracheal intubation success rate, glottic view and ease of tracheal intubation between the two groups. This study demonstrates that the LMA Protector supraglottic airway device is comparable to the i-gel supraglottic airway device as a conduit for fibreoptic-guided tracheal intubation.


Assuntos
Tecnologia de Fibra Óptica , Intubação Intratraqueal/instrumentação , Máscaras Laríngeas , Adulto , Idoso , Feminino , Humanos , Intubação Intratraqueal/métodos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
2.
Anaesthesia ; 73(7): 847-855, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29660807

RESUMO

Head and neck position is one of the factors which can be associated with difficult videolaryngoscopy and tracheal intubation. This prospective randomised clinical trial compared 'sniffing' and neutral positions using a channelled (KingVision® ) and a non-channelled (C-MAC® D-blade) videolaryngoscope in 200 adult patients randomly allocated into four groups (KingVision 'sniffing', KingVision neutral, C-MAC 'sniffing' and C-MAC neutral). The primary outcome was the ease of tracheal intubation using the modified intubation difficulty scale (mIDS) score. Laryngoscopy time, intubation time, laryngoscopic view using the percentage of glottic opening (POGO) score and success rate of tracheal intubation were secondary outcomes. The median (IQR [range]) modified difficulty scale scores for the four groups, respectively, were 0 (0-1 [0-3]), 0 (0-1 [0-4]), 1 (0-1 [0-5]) and 0 (0-1 [0-3]; p = 0.384). There was no significant difference in laryngoscopy time (p = 0.020), intubation time (p = 0.272) and success rate (p = 0.968) between the groups. The percentage of glottic opening score was lower for C-MAC neutral group as compared with other three groups (p = 0.01). There was no significant difference in the ease of intubation between the 'sniffing' and the neutral position when using the KingVision and the C-MAC videolaryngoscopes. Therefore, either of the two positions could be used with these types of videolaryngoscopes, if deemed advantageous for the patient.


Assuntos
Laringoscópios , Laringoscopia/métodos , Posicionamento do Paciente , Adulto , Idoso , Manuseio das Vias Aéreas/instrumentação , Manuseio das Vias Aéreas/métodos , Anestesia Geral , Feminino , Glote/anatomia & histologia , Humanos , Intubação Intratraqueal , Laringoscopia/instrumentação , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Gravação em Vídeo
3.
Org Biomol Chem ; 14(20): 4595-604, 2016 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-27031609

RESUMO

Several nucleotide-specific phosphohydrolases can cleave P-F bonds in substrate analogues containing a fluorophosphate moiety to release fluoride ions. In this work, by employing a fluoride-sensitive molecular sensor, we harnessed this cleavage reaction to develop a fluorescence assay to screen for phosphohydrolase inhibitors. The assay is rapid, sensitive, and based on simple and synthetically available reagents. The assay was adapted to the high-throughput screening (HTS) format and its utility was demonstrated by screening an 'in-house' library of small nucleotides against two enzymes: DcpS, a metal-independent mRNA decapping pyrophosphatase of the histidine triad (HIT) family; and PDE-I, a divalent cation-dependent nuclease. Our screening results agreed with the known specificities of DcpS and PDE-I, and led to the selection of several inhibitors featuring low-micromolar IC50 values. For DcpS, we also verified the results by using an alternative method with the natural substrate. Notably, the assay presented here is the first fluorescence-based HTS-adaptable assay for DcpS, an established therapeutic target for spinal muscular atrophy. The assay should be useful for phosphohydrolase specificity profiling and inhibitor discovery, particularly in the context of DcpS and other HIT-family enzymes, which play key roles in maintaining cellular functions and have been linked to disease development.


Assuntos
Nucleotídeo Cíclico Fosfodiesterase do Tipo 1/antagonistas & inibidores , Endorribonucleases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Ensaios de Triagem em Larga Escala/métodos , Capuzes de RNA/metabolismo , Animais , Crotalus , Humanos , Concentração Inibidora 50 , Espectrometria de Fluorescência
4.
Theor Appl Genet ; 127(5): 1073-90, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24567047

RESUMO

KEY MESSAGE: Proof of concept of Bayesian integrated QTL analyses across pedigree-related families from breeding programs of an outbreeding species. Results include QTL confidence intervals, individuals' genotype probabilities and genomic breeding values. Bayesian QTL linkage mapping approaches offer the flexibility to study multiple full sib families with known pedigrees simultaneously. Such a joint analysis increases the probability of detecting these quantitative trait loci (QTL) and provide insight of the magnitude of QTL across different genetic backgrounds. Here, we present an improved Bayesian multi-QTL pedigree-based approach on an outcrossing species using progenies with different (complex) genetic relationships. Different modeling assumptions were studied in the QTL analyses, i.e., the a priori expected number of QTL varied and polygenic effects were considered. The inferences include number of QTL, additive QTL effect sizes and supporting credible intervals, posterior probabilities of QTL genotypes for all individuals in the dataset, and QTL-based as well as genome-wide breeding values. All these features have been implemented in the FlexQTL(™) software. We analyzed fruit firmness in a large apple dataset that comprised 1,347 individuals forming 27 full sib families and their known ancestral pedigrees, with genotypes for 87 SSR markers on 17 chromosomes. We report strong or positive evidence for 14 QTL for fruit firmness on eight chromosomes, validating our approach as several of these QTL were reported previously, though dispersed over a series of studies based on single mapping populations. Interpretation of linked QTL was possible via individuals' QTL genotypes. The correlation between the genomic breeding values and phenotypes was on average 90 %, but varied with the number of detected QTL in a family. The detailed posterior knowledge on QTL of potential parents is critical for the efficiency of marker-assisted breeding.


Assuntos
Cruzamentos Genéticos , Malus/genética , Locos de Características Quantitativas , Teorema de Bayes , Cruzamento , Mapeamento Cromossômico , Cromossomos de Plantas , Frutas/anatomia & histologia , Frutas/genética , Estudos de Associação Genética , Ligação Genética , Genótipo , Malus/anatomia & histologia , Linhagem
5.
Eur J Gynaecol Oncol ; 34(5): 489-92, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24475592

RESUMO

Conservative treatment of metastatic germ-cell tumor of the ovary does not exclude the possibility of pregnancy in the future. Serum beta-human chorionic gonadotropin (beta-hCG) serves as pregnancy test, and has also been proven to be a useful marker for ovarian germ-cell tumors. This paper is a case report of a 19-year-old patient who was admitted to a district hospital in emergency due to pelvic pain, amenorrhoea, and free fluid in the pelvis. Laboratory tests demonstrated slight increase in beta-hCG serum concentration and transvaginal ultrasound (TVUS) showed no evidence of gestational sac in the uterus. At the age of 14, the patient was diagnosed with malignant germ-cell tumor of the left ovary in FIGO Stage IV and was treated with four courses of chemotherapy according to TGM-95 protocol with etoposide, ifosfamide, and cisplatin, followed by conservative surgery and adjuvant two courses of cytostatics. The initial diagnosis was recurrence of ovarian malignancy and the patient was referred to an oncology center. Wait-and-see approach and repeated ultrasound examination confirmed a normal intrauterine pregnancy which concluded with the delivery of a healthy newborn through cesarean section.


Assuntos
Gonadotropina Coriônica/sangue , Recidiva Local de Neoplasia/diagnóstico , Neoplasias Embrionárias de Células Germinativas/diagnóstico , Neoplasias Ovarianas/diagnóstico , Dor Pélvica/etiologia , Adulto , Feminino , Humanos , Recém-Nascido , Neoplasias Embrionárias de Células Germinativas/complicações , Neoplasias Ovarianas/complicações , Gravidez
6.
Clin Oral Investig ; 17(2): 579-83, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22476450

RESUMO

OBJECTIVES: The purpose of this study was to analyze the prevalence of dental erosion among competitive swimmers of the local swimming club in Szczecin, Poland, who train in closely monitored gas-chlorinated swimming pool water. MATERIALS AND METHODS: The population for this survey consisted of a group of junior competitive swimmers who had been training for an average of 7 years, a group of senior competitive swimmers who had been training for an average of 10 years, and a group of recreational swimmers. All subjects underwent a clinical dental examination and responded to a questionnaire regarding aspects of dental erosion. In pool water samples, the concentration of calcium, magnesium, phosphate, sodium, and potassium ions and pH were determined. The degree of hydroxyapatite saturation was also calculated. RESULTS: Dental erosion was found in more than 26 % of the competitive swimmers and 10 % of the recreational swimmers. The lesions in competitive swimmers were on both the labial and palatal surfaces of the anterior teeth, whereas erosions in recreational swimmers developed exclusively on the palatal surfaces. Although the pH of the pool water was neutral, it was undersaturated with respect to hydroxyapatite. CONCLUSION: The factors that increase the risk of dental erosion include the duration of swimming and the amount of training. An increased risk of erosion may be related to undersaturation of pool water with hydroxyapatite components. CLINICAL RELEVANCE: To decrease the risk of erosion in competitive swimmers, the degree of dental hydroxyapatite saturation should be a controlled parameter in pool water.


Assuntos
Cloro/uso terapêutico , Desinfetantes/uso terapêutico , Piscinas , Natação , Erosão Dentária/epidemiologia , Purificação da Água/métodos , Adolescente , Cálcio/análise , Dente Canino/patologia , Esmalte Dentário/patologia , Durapatita/análise , Feminino , Gases , Halogenação , Humanos , Concentração de Íons de Hidrogênio , Ácido Hipocloroso/química , Incisivo/patologia , Magnésio/análise , Masculino , Fosfatos/análise , Polônia/epidemiologia , Potássio/análise , Prevalência , Sódio/análise , Fatores de Tempo , Água/análise
7.
Pol J Vet Sci ; 14(4): 591-5, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22439330

RESUMO

This in vitro study evaluated the temperature rise on the outer root surface of the mandibular first molar following root canal filling using the high-temperature, thermoplasticized, Gutta-Percha technique (HTTG) (BeeFill) in the dog. Twelve extracted dog mandibular first molars were used. After root canal preparation, the teeth were filled with thermoplasticized Gutta-Percha and root canal sealer. Temperature changes on the vestibular surfaces of the mesial and distal roots of mandibular first molars were measured using a thermal imaging camera. The results of this in vitro study showed that using HTTG to fill mandibular first molars in dogs produces a safe temperature rise on the root surface and, therefore, should not damage the periodontal ligament and/or surrounding tissues.


Assuntos
Guta-Percha/química , Guta-Percha/uso terapêutico , Temperatura Alta , Tratamento do Canal Radicular/veterinária , Raiz Dentária , Animais , Cães , Materiais Restauradores do Canal Radicular/química , Materiais Restauradores do Canal Radicular/uso terapêutico , Tratamento do Canal Radicular/métodos
8.
Anal Chim Acta ; 1177: 338784, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34482902

RESUMO

In this study, two approaches to salivary glands studies are presented: Raman imaging (RI) of tissue cross-section and surface-enhanced Raman spectroscopy (SERS) of tissue homogenates prepared according to elaborated protocol. Collected and analyzed data demonstrate the significant potential of SERS combined with multivariate analysis for distinguishing carcinoma or tumor from the normal salivary gland tissues as a rapid, label-free tool in cancer detection in oncological diagnostics. Raman imaging allows a detailed analysis of the cell wall's chemical composition; thus, the compound's distribution can be semi-quantitatively analyzed, while SERS of tissue homogenates allow for detailed analysis of all moieties forming these tissues. In this sense, SERS is more sensitive and reliable to study any changes in the area of infected tissues. Principal component analysis (PCA), as an unsupervised pattern recognition method, was used to identify the differences in the SERS salivary glands homogenates. The partial least squares-discriminant analysis (PLS-DA), the supervised pattern classification technique, was also used to strengthen further the computed model based on the latent variables in the SERS spectra. Moreover, the chemometric quantification of obtained data was analyzed using principal component regression (PCR) multivariate calibration. The presented data prove that the PCA algorithm allows for 91% in seven following components and the determination between healthy and tumor salivary gland homogenates. The PCR and PLS-DA methods predict 90% and 95% of the variance between the studied groups (in 6 components and 4 factors, respectively). Moreover, according to calculated RMSEC (RMSEP), R2C (R2P) values and correlation accuracy (based on the ROC curve), the PLS-DA model fits better for the studied data. Thus, SERS methods combined with PLS-DA analysis can be used to differentiate healthy, neoplastic, and mixed tissues as a competitive tool in relation to the commonly used method of histopathological staining of tumor tissue.


Assuntos
Carcinoma , Análise Espectral Raman , Análise Discriminante , Humanos , Análise dos Mínimos Quadrados , Análise de Componente Principal
9.
Oper Dent ; 45(3): 306-317, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31750802

RESUMO

OBJECTIVE: This study evaluated the effect of etching mode and thermomechanical loading on universal adhesives. METHODS AND MATERIALS: Two universal adhesives, Peak Universal and Adhese Universal, were used in two etching modes as the experimental groups: Peak Universal etch-and-rinse (PER), Peak Universal self-etch (PSE), Adhese Universal etch-and-rinse (AER), and Adhese Universal self-etch (ASE). Two adhesives considered gold standards were used as control groups: OptiBond FL (OER) was used as a control group for the etch-and-rinse (ER) mode, and Clearfil SE Bond (CSE) was used as a control group for the self-etch (SE) mode. Standardized class V cavities were created on the buccal and lingual surface in 30 extracted caries-free human third molars. Each adhesive and resin composite was applied according to the manufacturer's instructions. The specimens were subjected to thermomechanical loading (TML) immediately after the fillings were placed. Before and after TML, replicas and photographs of the fillings were performed and evaluated quantitatively and qualitatively. The Mann-Whitney U-test or Kruskal-Wallis test was used for quantitative analyses, and Fisher exact test was used for qualitative analysis. RESULTS: Adhese Universal achieved a significantly higher percentage of continuous margin in the enamel than Peak Universal for the two types of etching both before and after TML (except for the SE group after TML). In dentin, the greatest percentage of continuous margin was achieved for Adhese Universal in the ER group (100%) before TML and for both universal adhesives in the SE groups (61%) after TML. For both etching modes and both time points, Adhese Universal had a greater percentage of continuous margin than Peak Universal for the whole margin. For the ER approach, significant differences were observed both before and after TML, and for the SE approach, significant differences were observed before TML. TML did not cause a significant decrease in the percentage of continuous margin in the enamel, but the results were the opposite in dentin. A qualitative assessment using World Dental Federation criteria did not show statistically significant differences between the groups. CONCLUSIONS: Scanning electron microscope assessment of marginal integrity showed that the evaluated factors such as etching mode and TML significantly influenced the marginal integrity of the universal adhesives. The replica method shows that laboratory and clinical assessment methods complement each other and give a broader view of marginal integrity.


Assuntos
Colagem Dentária , Adesivos Dentinários , Adesivos , Resinas Compostas , Cimentos Dentários , Humanos , Teste de Materiais , Cimentos de Resina
10.
Folia Morphol (Warsz) ; 79(4): 835-844, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31802476

RESUMO

BACKGROUND: The purpose of the study was to analyse mandibular anterior teeth in a Polish population and determine the symmetry of root and root canal morphology between the right and left side using cone-beam computed tomography (CBCT) scanning. MATERIALS AND METHODS: From 111 CBCT examinations, 303 pairs of equivalent mandibular anterior teeth were analysed on the right and left sides to evaluate symmetry. Axial, sagittal, and cross-sectional slices with a thickness of 0.2-0.25 mm were used. The number of root canals and their internal patterns were classified following Vertucci's criteria. RESULTS: All incisors in this study had 1 root. Canines usually had a single root and much less often had 2 roots. Type I and III root canal configurations were found most often, while type V and II configurations were less frequent. Significant compatibility between the left and right side was observed in all evaluated variables. Incisors had the highest symmetry with regard to the number of roots (100%). Second canals were observed more often in males than females, but only the results in lateral incisors were significant. CONCLUSIONS: This study provides supplemental information for dentists and should help them to better predict the morphology of mandibular anterior teeth in complicated cases in the Polish population. Symmetry was observed in roots and root canal morphology in all examined parameters.


Assuntos
Cavidade Pulpar , Raiz Dentária , Tomografia Computadorizada de Feixe Cônico , Estudos Transversais , Cavidade Pulpar/diagnóstico por imagem , Feminino , Humanos , Masculino , Mandíbula/diagnóstico por imagem , Polônia , Raiz Dentária/diagnóstico por imagem
11.
Neurobiol Learn Mem ; 90(1): 280-4, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18329298

RESUMO

We have investigated whether the left (LH) and right (RH) hemisphere play a different role in eliciting false recognition (FR) and whether their involvement in this memory illusion depends on the emotional content of stimuli. Negative and neutral pictures (taken from IAPS) were presented in the divided-visual field paradigm. Subjects task was to indicate whether the pictures had already been presented or not during the preceding study phase. FR rate was much higher for the RH than the LH presentations. In line, FR resulted in activations mainly in the right prefrontal cortex (PFC) for either RH or LH presentations. Emotional content of stimuli facilitated the formation of false memories and strengthened the involvement of the right PFC in FR induction.


Assuntos
Emoções/fisiologia , Lateralidade Funcional/fisiologia , Imageamento por Ressonância Magnética , Córtex Pré-Frontal/fisiologia , Reconhecimento Psicológico/fisiologia , Repressão Psicológica , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa
12.
Sci Rep ; 8(1): 14332, 2018 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-30254234

RESUMO

Conventional metal wires suffer from a significant degradation or complete failure in their electrical performance, when subjected to harsh oxidizing environments, however wires constructed from Carbon Nanotubes (CNTs) have been found to actually improve in their electrical performance when subjected to these environments. These opposing reactions may provide new and interesting applications for CNT wires. Yet, before attempting to move to any real-world harsh environment applications, for the CNT wires, it is essential that this area of their operation be thoroughly examined. To investigate this, CNT wires were treated with multiple combinations of the strongest acids and halogens. The wires were then subjected to conductivity measurements, current carrying capacity tests, as well as Raman, microscopy and thermogravimetric analysis to enable the identification of both the limits of oxidative conductivity boosting and the onset of physical damage to the wires. These experiments have led to two main conclusions. Firstly, that CNT wires may operate effectively in harsh oxidizing environments where metal wires would easily fail and secondly, that the highest conductivity increase of the CNT wires can be achieved through a process of annealing, acetone and HCl purification followed by either H2O2 and HClO4 or Br2 treatment.


Assuntos
Bromo/química , Condutividade Elétrica , Peróxido de Hidrogênio/química , Nanotubos de Carbono/química , Oxidantes/química , Percloratos/química , Oxirredução
13.
Sci Rep ; 7(1): 16438, 2017 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-29180637

RESUMO

The self-face has a prioritized status in the processing of incoming visual inputs. As the self-face changes over the lifespan, this stimulus seems to be well-suited for investigation of the self across time. Here, steady-state visual evoked potentials (SSVEP, oscillatory responses to periodic stimulation with a frequency that mirrors the frequency of stimulation) were used to investigate this topic. Different types of faces (present self, past self, close-other's, unknown, scrambled) flickered four times per second in two types of stimulation ('identical', with the same image of a given type of face; 'different', with different images of the same type of face). Each of the 10 stimulation sessions lasted 90 seconds and was repeated three times. EEG data were recorded and analyzed in 20 participants. In general, faces evoked higher SSVEP than scrambled faces. The impact of identical and different stimulation was similar for faces and scrambled faces: SSVEP to different stimuli (faces, scrambled faces) was enhanced in comparison to identical ones. Present self-faces evoked higher SSVEP responses than past self-faces in the different stimulation condition only. Thus, our results showed that the physical aspects of the present and past selves are differentiated on the neural level in the absence of an overt behavior.


Assuntos
Potenciais Evocados Visuais/fisiologia , Reconhecimento Facial , Autoimagem , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Estimulação Luminosa
14.
Oncogene ; 35(24): 3125-38, 2016 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-26500060

RESUMO

Activation of hypoxia-inducible factor (HIF) is due to loss of von Hippel-Lindau protein (pVHL) function in most clear cell renal cell carcinomas (ccRCCs). Here we describe a novel pVHL-independent mechanism of HIF regulation and identify nuclear factor (NF)-κB essential modulator (NEMO) as a hitherto unknown oncogenic factor influencing human ccRCC progression. Over 60% of human ccRCCs (n=157) have negative or weak NEMO protein expression by immunohistochemistry. Moderate/strong NEMO protein expression is more frequent in VHL wild-type ccRCCs. We show that NEMO stabilizes HIFα via direct interaction and independently of NF-κB signaling in vitro. NEMO prolongs tumor cell survival via regulation of apoptosis and activation of epithelial-to-mesenchymal transition, facilitating tumor metastasis. Our findings suggest that NEMO-driven HIF activation is involved in progression of ccRCC. Therefore, NEMO may represent a clinically relevant link between NF-κB and the VHL/HIF pathways. Targeting NEMO with specific inhibitors in patients with metastatic ccRCC could be a novel treatment approach in patients with ccRCC expressing functional pVHL.


Assuntos
Carcinoma de Células Renais/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Quinase I-kappa B/metabolismo , Neoplasias Renais/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Animais , Carcinoma de Células Renais/patologia , Morte Celular/fisiologia , Movimento Celular/fisiologia , Progressão da Doença , Feminino , Xenoenxertos , Humanos , Neoplasias Renais/patologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , NF-kappa B/metabolismo , Transdução de Sinais , Regulação para Cima
15.
BMC Evol Biol ; 1: 13, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11801180

RESUMO

BACKGROUND: Any DNA sequence is a result of compromise between the selection and mutation pressures exerted on it during evolution. It is difficult to estimate the relative influence of each of these pressures on the rate of accumulation of substitutions. However, it is important to discriminate between the effect of mutations, and the effect of selection, when studying the phylogenic relations between taxa. RESULTS: We have tested in computer simulations, and analytically, the available substitution matrices for many genomes, and we have found that DNA strands in equilibrium under mutational pressure have unique feature: the fraction of each type of nucleotide is linearly dependent on the time needed for substitution of half of nucleotides of a given type, with a correlation coefficient close to 1. Substitution matrices found for sequences under selection pressure do not have this property. A substitution matrix for the leading strand of the Borrelia burgdorferi genome, having reached equilibrium in computer simulation, gives a DNA sequence with nucleotide composition and asymmetry corresponding precisely to the third positions in codons of protein coding genes located on the leading strand. CONCLUSIONS: Parameters of mutational pressure allow us to count DNA composition in equilibrium with this mutational pressure. Comparing any real DNA sequence with the sequence in equilibrium it is possible to estimate the distance between these sequences, which could be used as a measure of the selection pressure. Furthermore, the parameters of the mutational pressure enable direct estimation of the relative mutation rates in any DNA sequence in the studied genome.


Assuntos
DNA Bacteriano/genética , Mutagênese , Nucleotídeos/metabolismo , Composição de Bases/genética , Borrelia burgdorferi/genética , Inversão Cromossômica , Códon/genética , Simulação por Computador , DNA Bacteriano/química , DNA Intergênico/genética , Evolução Molecular , Genes Bacterianos/genética , Genoma Bacteriano , Modelos Genéticos
16.
Neuropsychologia ; 34(2): 147-51, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8852877

RESUMO

The study investigated directional differences in interhemispheric transmission time using the VEPs method. Specifically we were interested in whether there exists an asymmetry in the transmission of information to and from the hemisphere specialized in its processing. Two type of stimuli, specific for the left and right hemisphere, were presented in the left and right visual fields. The latency differences between visual evoked potential components registered in the hemispheres ipsilateral and contralateral to the stimulated hemifield were compared. Interhemispheric transmission time was shorter when the information was transferred from the hemisphere non-specialized for its processing to the specialized one than in the opposite direction. The results suggest the existence of a physiological mechanism that ensures fast transmission of information to that hemisphere which is more efficient in its processing.


Assuntos
Encéfalo/fisiologia , Lateralidade Funcional , Potenciais Evocados Visuais , Humanos
17.
Biochimie ; 83(8): 739-42, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11530205

RESUMO

Human blood platelets release alpha-6-fucosyltransferase during coagulation of blood or after stimulation with thrombin or other agonists that cause platelet activation (Antoniewicz et al., FEBS Lett. 244 (1989) 388-390). However, in the absence of neutrophils the thrombin-stimulated platelets release only a small fraction of alpha-6-fucosyltransferase activity (Koscielak et al., Acta Biochim. Polon. 42 (1995) 35-40). We show that the effect of neutrophils is reproduced by cathepsin G or (less efficiently) by elastase, the two enzymes that are released by neutrophils during coagulation of blood. We have also localized alpha-6-fucosyltransferase to membrane and alpha-granule fractions of platelets that had been disrupted by nitrogen cavitation. It is concluded that thrombin-activated neutrophils release cathepsin G and elastase that promote degranulation of platelets and hence the secretion of alpha-6-fucosyltransferase.


Assuntos
Plaquetas/enzimologia , Catepsinas/metabolismo , Fucosiltransferases/metabolismo , Elastase de Leucócito/metabolismo , Neutrófilos/enzimologia , Serina Endopeptidases/metabolismo , Difosfato de Adenosina/farmacologia , Plaquetas/citologia , Plaquetas/efeitos dos fármacos , Catepsina G , Catepsinas/farmacologia , Células Cultivadas , Humanos , Elastase de Leucócito/farmacologia , Neutrófilos/fisiologia , Trombina/farmacologia
18.
Psychol Bull ; 120(3): 434-49, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8900082

RESUMO

In this article, the authors present a review of research on the role of the 2 hemispheres in processing spatial frequencies. J. Sergent (1982a) postulated that the hemispheres differ in their sensitivity to frequency characteristics of the sensory outputs on which cognitive processes are performed. Specifically, she proposed that the right hemisphere displays greater efficiency than the left hemisphere in processing low-spatial-frequency content of a visual image, whereas the left hemisphere is better equipped than the right to deal with high frequencies. The authors present an extensive review of behavioral and electrophysiological studies whose researchers tried to verify Sergent's hypothesis and offer its reformulation, taking into account the findings that have accumulated in the last 10 years.


Assuntos
Encéfalo/fisiologia , Percepção Espacial/fisiologia , Campos Visuais , Lateralidade Funcional , Humanos
19.
Neuroreport ; 12(18): 4171-5, 2001 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-11742259

RESUMO

Many studies on hemispheric specialization for language functions and on morphology of the corpus callosum have revealed stronger lateralization and smaller splenium area in men than in women. We have tested the related prediction that interhemispheric transmission times (IHTTs) of verbal information differ in the two sexes using event-related potentials (ERPs) for determining IHTTs in male and female subjects. The IHTTs were estimated as latency differences between early components of ERPs, recorded in response to words from symmetrical sites of directly and indirectly stimulated hemisphere, i.e. the hemisphere contralateral and ipsilateral to the visual hemifield of stimulus presentation. In women, IHTTs were similar for the left-to-right and right-to-left directions, whereas in men, IHTTs were directionally asymmetrical and were considerably longer for the left-to-right direction.


Assuntos
Córtex Cerebral/fisiologia , Dominância Cerebral/fisiologia , Caracteres Sexuais , Adulto , Análise de Variância , Corpo Caloso/fisiologia , Eletroencefalografia , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Masculino , Tempo de Reação/fisiologia , Aprendizagem Verbal/fisiologia
20.
Neuroreport ; 12(10): 2289-92, 2001 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-11447351

RESUMO

The aim of the study was to investigate the effect of unilateral brain lesions on the perception of subjective contours. Brain damage resulted in a reduced ability to perceive the illusion. The effect, however, was hemisphere and sex dependent. In women an illusion decrement due to either the left or right hemisphere damage was observed, while in men only right hemisphere damage caused a decrement. No specific effect of intrahemispheric localisation of lesion was found. We conclude that mechanisms contributing to subjective contour perception are right hemisphere dependent in males whereas in females they are bilaterally represented.


Assuntos
Percepção de Forma/fisiologia , Lateralidade Funcional/fisiologia , Hipóxia Encefálica/fisiopatologia , Ilusões/fisiologia , Caracteres Sexuais , Adulto , Idoso , Análise de Variância , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA