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1.
Neurosci Lett ; 822: 137628, 2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38191088

RESUMO

Dorsal root ganglia (DRG) neurons transduce and convey somatosensory information from the periphery to the central nervous system. Adrenergic mediators are known to modulate nociceptive inputs in DRG neurons, acting as up- or down-regulators of neuronal excitability. They are also important in the development of sympathetic neuropathy. ATP-activated P2X channels and capsaicin-activated TRPV1 channels are directly involved in the transduction of nociceptive stimuli. In this work, we show that long-term (up to 3 days) in vitro stimulation of DRG neurons with selective α1-adrenergic agonist increased slow but not fast ATP-activated currents, with no effect on capsaicin currents. Selective agonists for α2, ß1 and ß3-adrenergic receptors decreased capsaicin activated currents and had no effect on ATP currents. Capsaicin currents were associated with increased neuronal excitability, while none of the adrenergic modulators produced change in rheobase. These results demonstrate that chronic adrenergic activation modulates two nociceptive transducer molecules, increasing or decreasing channel current depending on the adrenergic receptor subtype. These observations aid our understanding of nociceptive or antinociceptive effects of adrenergic agonists.


Assuntos
Agonistas Adrenérgicos , Capsaicina , Capsaicina/farmacologia , Agonistas Adrenérgicos/farmacologia , Nociceptividade , Canais Iônicos/farmacologia , Trifosfato de Adenosina/farmacologia , Gânglios Espinais , Canais de Cátion TRPV
2.
An Acad Bras Cienc ; 95(suppl 1): e20220514, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37493694

RESUMO

Different degrees in the biological activities of Canavalia rosea had been previously reported . In this study, our group assessed the cardioprotective effects of the ethyl acetate fraction (EAcF) of the Canavalia rosea leaves. Firstly, it was confirmed, by in vitro approach, that the EAcF has high antioxidant properties due to the presence of important secondary metabolites, as flavonoids. In order to explore their potential protector against cardiovascular disorders, hearts were previously perfused with EAcF (300 µg.mL-1) and submitted to the global ischemia followed by reperfusion in Langendorff system. The present findings have demonstrated that EAcF restored the left ventricular developed pressure and decreased the arrhythmias severity index. Furthermore, EAcF significantly increased the glutathiones peroxidase activity with decreased malondialdehyde and creatine kinase levels. EAcF was effective upon neither the superoxide dismutase, glutationes reductase nor the catalase activities. In addition, the Western blot analysis revealed that ischemia-reperfusion injury significantly upregulates caspase 3 protein expression, while EAcF abolishes this effect. These results provide evidence that the EAcF reestablishes the cardiac contractility and prevents arrhythmias; it is suggested that EAcF could be used to reduce injury caused by cardiac reperfusion. However more clinical studies should be performed, before applying it in the clinic.


Assuntos
Antioxidantes , Traumatismo por Reperfusão Miocárdica , Ratos , Animais , Humanos , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Canavalia/metabolismo , Ratos Sprague-Dawley , Superóxido Dismutase/metabolismo , Folhas de Planta/metabolismo , Miocárdio/metabolismo
3.
EJNMMI Phys ; 9(1): 91, 2022 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-36577862

RESUMO

BACKGROUND AND AIMS: Molecular imaging of the dopamine transporters (DAT) provides valuable information about neurodegenerative diseases, such as Parkinson's. This study assessed the accuracy and precision of DAT-SPECT quantification methods. METHODS: Twenty-three DAT-SPECT images of a striatal phantom were acquired. The specific (caudate and putamen) and the non-specific (background activity) chambers were filled with [99mTc]Tc. Different specific-to-non-specific activity ratios (10, 9, 8, 7, 6, 5, 4, 3 and 2 to 1) and the specific binding ratio (SBR) were calculated. Five methods using ROIs were assessed: (a) Manual ROIs on SPECT images; (b) TwoBox and (c) ThreeBox methods and Volume of Interest (VOI) using structural images; (d) MRI and (e) CT. Accuracy was evaluated by the concordance correlation coefficient (CCC) and precision by Pearson's coefficient and linear regression. RESULTS: The SBR quantified in the specific and striatal chambers resulted in a CCC increase with a decrease in the nominal values. For lower SBR, MRI and CT showed higher CCCs when caudate ([Formula: see text] = 0.89 e [Formula: see text] = 0.84) and putamen ([Formula: see text] = 0.86 e [Formula: see text] = 0.82) were evaluated. For striatal assessments, the TwoBox method was the most accurate ([Formula: see text] = 0.95). High Pearson's coefficients were found in the correlations between all methods. CONCLUSIONS: All five methods showed high precision even when applied to images with different activities. MRI and CT were the most accurate for assessing the caudate or putamen. To assess the striatal chamber and in the absence of structural information, the TwoBox method is advisable.

5.
Biochimie ; 176: 138-149, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32717411

RESUMO

Spider venoms, despite their toxicity, represent rich sources of pharmacologically active compounds with biotechnological potential. However, in view of the large diversity of the spider species, the full potential of their venom molecules is still far from being known. In this work, we report the purification and structural and functional characterization of GiTx1 (ß/κ-TRTX-Gi1a), the first toxin purified from the venom of the Brazilian tarantula spider Grammostola iheringi. GiTx1 was purified by chromatography, completely sequenced through automated Edman degradation and tandem mass spectrometry and its structure was predicted by molecular modeling. GiTx1 has a MW of 3.585 Da, with the following amino acid sequence: SCQKWMWTCDQKRPCCEDMVCKLWCKIIK. Pharmacological activity of GiTx1 was characterized by electrophysiology using whole-cell patch clamp on dorsal root ganglia neurons (DRG) and two-electrode voltage-clamp on voltage-gated sodium and potassium channels subtypes expressed in Xenopus laevis oocytes. GiTx1, at 2 µM, caused a partial block of inward (∼40%) and outward (∼20%) currents in DRG cells, blocked rNav1.2, rNav1.4 and mNav1.6 and had a significant effect on VdNav, an arachnid sodium channel isoform. IC50 values of 156.39 ± 14.90 nM for Nav1.6 and 124.05 ± 12.99 nM for VdNav, were obtained. In addition, this toxin was active on rKv4.3 and hERG potassium channels, but not Shaker IR or rKv2.1 potassium channels. In summary, GiTx1 is a promiscuous toxin with multiple effects on different types of ion channels.


Assuntos
Canais de Potássio de Abertura Dependente da Tensão da Membrana , Venenos de Aranha , Aranhas/química , Bloqueadores do Canal de Sódio Disparado por Voltagem , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , Moscas Domésticas , Humanos , Camundongos , Canais de Potássio de Abertura Dependente da Tensão da Membrana/antagonistas & inibidores , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Domínios Proteicos , Ratos , Ratos Wistar , Venenos de Aranha/química , Venenos de Aranha/isolamento & purificação , Venenos de Aranha/toxicidade , Bloqueadores do Canal de Sódio Disparado por Voltagem/química , Bloqueadores do Canal de Sódio Disparado por Voltagem/isolamento & purificação , Bloqueadores do Canal de Sódio Disparado por Voltagem/toxicidade , Canais de Sódio Disparados por Voltagem/química
6.
Biophys Rev ; 9(5): 847-856, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28889335

RESUMO

First-order somatosensory neurons transduce and convey information about the external or internal environment of the body to the central nervous system. They are pseudo unipolar neurons with cell bodies residing in one of several ganglia located near the central nervous system, with the short branch of the axon connecting to the spinal cord or the brain stem and the long branch extending towards the peripheral organ they innervate. Besides their sensory transducer and conductive role, somatosensory neurons also have trophic functions in the tissue they innervate and participate in local reflexes in the periphery. The cell bodies of these neurons are remarkably diverse in terms of size, molecular constitution, and electrophysiological properties. These parameters have provided criteria for classification that have proved useful to establish and study their functions. In this review, we discuss ways to measure and classify populations of neurons based on their size and action potential firing pattern. We also discuss attempts to relate the different populations to specific sensory modalities.

7.
Nucl Med Commun ; 38(10): 837-842, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28777221

RESUMO

OBJECTIVE: The aim of this study was to evaluate angular, spatial, and energy resolution, sensitivity, and shielding of a gamma-probe. MATERIALS AND METHODS: The EUROPROBE II gamma-probe (EuroRad) with sources of technetium-99m was assessed according to NEMA NU-3-2004. Resolution tests were evaluated considering the full width at half maximum (FWHM). The following parameters were evaluated: angular resolution in air, spatial resolution with a scattering medium and in air, energy resolution, and sensitivity and shielding. The collimator was used to evaluate angular and spatial resolution, sensitivity, and shielding. Background radiation was considered and did not affect the counts. RESULTS: FWHM of angular resolution (at 3/30 cm) was 39.17°/33.13° with the collimator and 74.08°/71.51° without the collimator; FWHM of spatial resolution in air at 10 mm was 13.32 mm with the collimator and 21.23 mm without the collimator. Energy resolution (%FWHM) was 20.51%. Sensitivity at 10 mm was 4.642±5 cps/MBq without the collimator and 1.063±2 cps/MBq with the collimator; shielding effectiveness of the probe tip was 99.52%. Background was not relevant to the counts. CONCLUSION: We showed that the collimator improved angular and spatial resolution to the detriment of sensitivity. Feasible results of energy resolution, sensitivity, and shielding were achieved.


Assuntos
Raios gama , Proteção Radiológica , Biópsia de Linfonodo Sentinela/instrumentação , Raios gama/efeitos adversos , Biópsia de Linfonodo Sentinela/efeitos adversos , Tecnécio/efeitos adversos
8.
Nucl Med Commun ; 37(1): 87-91, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26457596

RESUMO

PURPOSE: This paper presents a novel method to compute oesophageal transit velocity in a direct and automatized manner by the registration of scintigraphy images. METHODS: A total of 36 images from nine healthy volunteers were processed. Four dynamic image series per volunteer were acquired after a minimum 8 h fast. Each acquisition was made following the ingestion of 5 ml saline labelled with about 26 MBq (700 µCi) technetium-99m phytate in a single swallow. Between the acquisitions, another two swallows of 5 ml saline were performed to clear the oesophagus. The composite acquired files were made of 240 frames of anterior and posterior views. Each frame is the accumulate count for 250 ms.At the end of acquisitions, the images were corrected for radioactive decay, the geometric mean was computed between the anterior and posterior views and the registration of a set of subsequent images was performed. Utilizing the improved Demons technique, we obtained from the deformation field the regional resultant velocity, which is directly related to the oesophagus transit velocity. RESULTS: The mean regional resulting velocities decreases progressively from the proximal to the distal oesophageal portions and, at the proximal portion, is virtually identical to the primary peristaltic pump typical velocity. Comparison between this parameter and 'time-activity' curves reveals consistency in velocities obtained using both methods, for the proximal portion. CONCLUSION: Application of the improved Demons technique, as an easy and automated method to evaluate velocities of oesophageal bolus transit, is feasible and seems to yield consistent data, particularly for the proximal oesophagus.


Assuntos
Esôfago/diagnóstico por imagem , Esôfago/fisiologia , Trânsito Gastrointestinal , Processamento de Imagem Assistida por Computador/métodos , Adulto , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Cintilografia
9.
Biomed Tech (Berl) ; 60(3): 235-44, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25781658

RESUMO

Fetal magnetocardiograms (fMCGs) have been successfully processed with independent component analysis (ICA) to separate the fetal cardiac signals, but ICA effectiveness can be limited by signal nonstationarities due to fetal movements. We propose an ICA-based method to improve the quality of fetal signals separated from fMCG affected by fetal movements. This technique (SegICA) includes a procedure to detect signal nonstationarities, according to which the fMCG recordings are divided in stationary segments that are then processed with ICA. The first and second statistical moments and the signal polarity reversal were used at different threshold levels to detect signal transients. SegICA effectiveness was assessed in two fMCG datasets (with and without fetal movements) by comparing the signal-to-noise ratio (SNR) of the signals extracted with ICA and with SegICA. Results showed that the SNR of fetal signals affected by fetal movements improved with SegICA, whereas the SNR gain was negligible elsewhere. The best measure to detect signal nonstationarities of physiological origin was signal polarity reversal at threshold level 0.9. The first statistical moment also provided good results at threshold level 0.6. SegICA seems a promising method to separate fetal cardiac signals of improved quality from nonstationary fMCG recordings affected by fetal movements.


Assuntos
Algoritmos , Eletrocardiografia/métodos , Frequência Cardíaca Fetal/fisiologia , Processamento de Sinais Assistido por Computador/instrumentação , Feminino , Humanos , Gravidez , Razão Sinal-Ruído
10.
Nucl Med Commun ; 36(1): 95-101, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25299468

RESUMO

Duodenal contractions are thought to play a role in the control of gastric emptying. Although noninvasive techniques, such as ultrasonography and MRI, have been proposed for studying duodenal contractile activity in humans, there are no reports on the use of scintigraphy for this purpose. This work aimed to describe a novel scintigraphic technique for assessing duodenal contractility during gastric emptying in humans, and to present preliminary data on the frequency and amplitude of contractions detected in three different duodenal segments. Fasted young healthy volunteers (N=12) were given either a liquid or a solid test meal of similar calorie content (400 kcal) labeled with 99mTc-phytate. Static images were collected to determine gastric emptying. Dynamic images of the anterior aspect of the abdomen (1 frame/s) were also acquired periodically in a standard position for 256 s at 15-30 min intervals. 'Activity versus time' curves were generated for regions of interest corresponding to the proximal, middle, and distal duodenal segments. Curves were digitally filtered and processed to estimate both dominant frequency (fast Fourier transform) and amplitude (mean ejection fraction) of postprandial duodenal contractions. There were no significant differences regarding dominant frequency among proximal, middle, and distal duodenal regions of interest. In addition, there were no significant differences between the liquid and the solid meal in terms of either frequency or amplitude of duodenal contractions. Characterization of duodenal contractions in humans using scintigraphy is feasible and yields consistent data for both the frequency and the amplitude of postprandial contractions, which seems to be rather independent of meal consistency.


Assuntos
Duodeno/fisiologia , Esvaziamento Gástrico , Contração Muscular , Cintilografia/métodos , Jejum , Estudos de Viabilidade , Feminino , Humanos , Masculino , Adulto Jovem
11.
Phys Med ; 31(1): 43-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25240897

RESUMO

GATE is public domain software widely used for Monte Carlo simulation in emission tomography. Validations of GATE have primarily been performed on a whole-system basis, leaving the possibility that errors in one sub-system may be offset by errors in others. We assess the accuracy of the GATE PET coincidence generation sub-system in isolation, focusing on the options most closely modeling the majority of commercially available scanners. Independent coincidence generators were coded by teams at Toshiba Medical Research Unit (TMRU) and UC Davis. A model similar to the Siemens mCT scanner was created in GATE. Annihilation photons interacting with the detectors were recorded. Coincidences were generated using GATE, TMRU and UC Davis code and results compared to "ground truth" obtained from the history of the photon interactions. GATE was tested twice, once with every qualified single event opening a time window and initiating a coincidence check (the "multiple window method"), and once where a time window is opened and a coincidence check initiated only by the first single event to occur after the end of the prior time window (the "single window method"). True, scattered and random coincidences were compared. Noise equivalent count rates were also computed and compared. The TMRU and UC Davis coincidence generators agree well with ground truth. With GATE, reasonable accuracy can be obtained if the single window method option is chosen and random coincidences are estimated without use of the delayed coincidence option. However in this GATE version, other parameter combinations can result in significant errors.


Assuntos
Tomografia por Emissão de Pósitrons , Software , Algoritmos , Processamento de Imagem Assistida por Computador , Método de Monte Carlo , Imagens de Fantasmas
12.
Mol Pain ; 10: 73, 2014 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-25431155

RESUMO

BACKGROUND: Substance P modulates ion channels and the excitability of sensory neurons in pain pathways. Within the heterogeneous population of Dorsal Root Ganglia (DRG) primary sensory neurons, the properties of cells that are sensitive to Substance P are poorly characterized. To define this population better, dissociated rat DRG neurons were tested for their responsiveness to capsaicin, ATP and acid. Responses to ATP were classified according to the kinetics of current activation and desensitization. The same cells were then tested for modulation of action potential firing by Substance P. RESULTS: Acid and capsaicin currents were more frequently encountered in the largest diameter neurons. P2X3-like ATP currents were concentrated in small diameter neurons. Substance P modulated the excitability in 20 of 72 cells tested (28%). Of the Substance P sensitive cells, 10 exhibited an increase in excitability and 10 exhibited a decrease in excitability. There was no significant correlation between sensitivity to capsaicin and to Substance P. Excitatory effects of Substance P were strongly associated with cells that had large diameters, fired APs with large overshoots and slowly decaying after hyperpolarizations, and expressed acid currents at pH 7. No neurons that were excited by Substance P presented P2X3-like currents. In contrast, neurons that exhibited inhibitory effects of Substance P fired action potentials with rapidly decaying after hyperpolarizations. CONCLUSION: We conclude that excitatory effects of Substance P are restricted to a specific neuronal subpopulation with limited expression of putative nociceptive markers.


Assuntos
Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Substância P/metabolismo , Potenciais de Ação/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo , Animais , Capsaicina/química , Concentração de Íons de Hidrogênio , Masculino , Distribuição Normal , Ratos , Ratos Wistar , Receptores Purinérgicos P2X3/metabolismo , Canais de Cátion TRPV/metabolismo
13.
Int Arch Med ; 6(1): 38, 2013 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-24099489

RESUMO

BACKGROUND: Coactivation may be both desirable (injury prevention) or undesirable (strength measurement). In this context, different styles of muscle strength stimulus have being investigated. In this study we evaluated the effects of verbal and visual stimulation on rectus femoris and biceps femoris muscles contraction during isometric and concentric. METHODS: We investigated 13 men (age =23.1 ± 3.8 years old; body mass =75.6 ± 9.1 kg; height =1.8 ± 0.07 m). We used the isokinetic dynamometer BIODEX device and an electromyographic (EMG) system. We evaluated the maximum isometric and isokinetic knee extension and flexion at 60°/s. The following conditions were evaluated: without visual nor verbal command (control); verbal command; visual command and; verbal and visual command. In relation to the concentric contraction, the volunteers performed five reciprocal and continuous contractions at 60°/s. With respect to isometric contractions it was made three contractions of five seconds for flexion and extension in a period of one minute. RESULTS: We found that the peak torque during isometric flexion was higher in the subjects in the VVC condition (p > 0.05). In relation to muscle coactivation, the subjects presented higher values at the control condition (p > 0.05). CONCLUSION: We suggest that this type of stimulus is effective for the lower limbs.

14.
Physiol Meas ; 33(10): 1563-83, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22945491

RESUMO

We analyzed the effectiveness of linear short- and long-term variability time domain parameters, an index of sympatho-vagal balance (SDNN/RMSSD) and entropy in differentiating fetal heart rate patterns (fHRPs) on the fetal heart rate (fHR) series of 5, 3 and 2 min duration reconstructed from 46 fetal magnetocardiograms. Gestational age (GA) varied from 21 to 38 weeks. FHRPs were classified based on the fHR standard deviation. In sleep states, we observed that vagal influence increased with GA, and entropy significantly increased (decreased) with GA (SDNN/RMSSD), demonstrating that a prevalence of vagal activity with autonomous nervous system maturation may be associated with increased sleep state complexity. In active wakefulness, we observed a significant negative (positive) correlation of short-term (long-term) variability parameters with SDNN/RMSSD. ANOVA statistics demonstrated that long-term irregularity and standard deviation of normal-to-normal beat intervals (SDNN) best differentiated among fHRPs. Our results confirm that short- and long-term variability parameters are useful to differentiate between quiet and active states, and that entropy improves the characterization of sleep states. All measures differentiated fHRPs more effectively on very short HR series, as a result of the fMCG high temporal resolution and of the intrinsic timescales of the events that originate the different fHRPs.


Assuntos
Feto/fisiologia , Frequência Cardíaca , Magnetocardiografia/métodos , Análise de Variância , Comportamento/fisiologia , Feminino , Desenvolvimento Fetal/fisiologia , Idade Gestacional , Humanos , Modelos Lineares , Dinâmica não Linear , Gravidez , Fatores de Risco , Processamento de Sinais Assistido por Computador , Fatores de Tempo
15.
Pharmacology ; 89(3-4): 137-44, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22414617

RESUMO

The G protein-coupled receptor Mas was recently described as an angiotensin-(1-7) [Ang-(1-7)] receptor. In the present study, we demonstrate an antinociceptive effect of Ang-(1-7) for the first time. Additionally, we evaluated the anatomical localization of Mas in the dorsal root ganglia using immunofluorescence. This is the first evidence indicating that this receptor is present in sensitive neurons. The antinociceptive effect was demonstrated using the rat paw pressure test. For this test, sensitivity is increased by intraplantar injection of prostaglandin E(2). Ang-(1-7) administered locally into the right hind paw elicited a dose-dependent antinociceptive effect. Because the higher dose of Ang-(1-7) did not produce an effect when injected into the contralateral paw, this effect was considered local. The specific antagonist for the Mas receptor, A-779, inhibited the peripheral antinociception induced by exposure to 4 µg/paw Ang-(1-7) in a dose-dependent manner. The highest dose completely reversed the antinociceptive effect induced by Ang-(1-7), suggesting that the Mas receptor is an obligatory component in this process and that other angiotensin receptors may not be involved. When injected alone, the antagonist was unable to induce hyperalgesia or antinociception. Alternatively, naloxone was unable to inhibit the antinociceptive effect induced by Ang-(1-7), suggesting that endogenous opioid peptides may not be involved in this response. These data provide the first anatomical basis for the physiological role of Ang-(1-7) in the modulation of pain perception via Mas receptor activation in an opioid-independent pathway. Taken together, these results provide new perspectives for the development of a new class of analgesic drugs.


Assuntos
Analgésicos/uso terapêutico , Angiotensina II/análogos & derivados , Hiperalgesia/tratamento farmacológico , Fragmentos de Peptídeos/uso terapêutico , Proteínas Proto-Oncogênicas/fisiologia , Receptores Acoplados a Proteínas G/fisiologia , Angiotensina II/farmacologia , Angiotensina II/uso terapêutico , Animais , Dinoprostona , Gânglios Espinais/metabolismo , Hiperalgesia/induzido quimicamente , Hiperalgesia/fisiopatologia , Masculino , Fragmentos de Peptídeos/farmacologia , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G/antagonistas & inibidores
16.
Neurotox Res ; 19(1): 102-14, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20020338

RESUMO

We examined modification of sodium channel gating by Tityus bahiensis scorpion venom (TbScV), and compared effects on native tetrodotoxin-sensitive and tetrodotoxin-resistant sodium currents from rat dorsal root ganglion neurons and cardiac myocytes. In neurons, TbScV dramatically reduced the rate of sodium current inactivation, increased current amplitude, and caused a negative shift in the voltage-dependence of activation and inactivation of tetrodotoxin-sensitive channels. Enhanced activation of modified sodium channels was independent of a depolarizing prepulse. We identified two components of neuronal tetrodotoxin-resistant current with biophysical properties similar to those described for NaV1.8 and NaV1.9. In contrast to its effects on neuronal tetrodotoxin-sensitive current, TbScV caused a small decrease in neuronal tetrodotoxin-resistant sodium current amplitude and the gating modifications described above were absent. A third tetrodotoxin-resistant current, NaV1.5 recorded in rat cardiac ventricular myocytes, was inhibited approximately 50% by TbScV, and the remaining current exhibited markedly slowed activation and inactivation. In conclusion, TbScV has very different effects on different sodium channel isoforms. Among the neuronal types, currents resistant to tetrodotoxin are also resistant to gating modification by TbScV. The cardiac tetrodotoxin-resistant current has complex sensitivity that includes both inhibition of current amplitude and slowing of activation and inactivation.


Assuntos
Venenos de Escorpião/farmacologia , Bloqueadores dos Canais de Sódio/farmacologia , Canais de Sódio/metabolismo , Tetrodotoxina/farmacologia , Animais , Células Cultivadas , Resistência a Medicamentos , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/fisiologia , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/fisiologia , Masculino , Canal de Sódio Disparado por Voltagem NAV1.5 , Canal de Sódio Disparado por Voltagem NAV1.8 , Canal de Sódio Disparado por Voltagem NAV1.9 , Ratos , Ratos Wistar , Agonistas de Canais de Sódio , Canais de Sódio/fisiologia
17.
Rev. bras. anal. clin ; 41(3): 197-199, 2009. tab, graf
Artigo em Português | LILACS | ID: lil-544441

RESUMO

As metalo-beta-lactamases (MBLs) pertencem ao grupo 3 de beta-lactamases de espectro estendido, fazendo parte de uma classefuncional de metaloenzimas classificadas com base na sua capacidade de hidrolisar os carbapenemicos como o Imipenem e em suas caracteristicas de serem inibidas por agentes quelantes como o acido etilenodiamino tetra-acetico (EDTA) e acido 2-mercaptopropionico (2-MPA). Este estudo objetivou a deteccao de MBLs em amostras nosocomiais de P. aeruginosa resistentes a Ceftazidima, provenientes de um hospital de medio porte de Porto Alegre-RS. Foram analisados 113 isolados clinicos atraves de testes fenotipicos, sendo: 80 (70,7%) do trato respiratorio inferior, 24 (21,2%) urina, 3 (2,7%) hemocultura, 3 (2,7%) ponta de cateter, 2 (1,8%) colecao de cavidadese 1 (0,9%) liquor. Com relacao a producao de MBLs, detectou-se 35 amostras (31,0%) como sendo produtoras.


Metallo-beta-lactamases belongs to the group 3 of extended spectrum beta-lactamases, making part of a common functional class of metal enzymes classified based in their ability to hydrolyze Imipenem and in your characteristics of been inhibited by ions of chelating metals, like EDTA and 2-MPA. The aim of this study was detect MBLs in samples of P. aeruginosa resistant to ceftazidime in the patients of PortoAlegre- RS Brazil. The samples was provided of different clinical specimens like: 80 (70,7%) respiratory tract, 24 (21,2%) urine, blood 3 (2,7%), catheter 3 (2,7%), 2 (1,8%) corporeal secretions and 1 (0,9%) liquor. With regard to the MBLs production, we detect 35 (31%) as being producing.


Assuntos
beta-Lactamases , Resistência às Cefalosporinas , Farmacorresistência Bacteriana , Imipenem/uso terapêutico , Pseudomonas aeruginosa , Resistência a Vancomicina , Cefalosporinas , Vancomicina
18.
Ann Nucl Med ; 22(9): 761-7, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19039554

RESUMO

OBJECTIVE: This work aimed at determining whether data from dynamic antral scintigraphy (DAS) yielded by a simple, manual technique are as accurate as those generated by a conventional automated technique (fast Fourier transform) for assessing gastric contractility. METHODS: Seventy-one stretches (4 min) of "activity versus time" curves obtained by DAS from 10 healthy volunteers and 11 functional dyspepsia patients, after ingesting a liquid meal (320 ml, 437 kcal) labeled with technetium-99m (99mTc)-phytate, were independently analyzed by manual and automated techniques. RESULTS: Data obtained by both techniques for the frequency of antral contractions were similar. Contraction amplitude determined by the manual technique was significantly higher than that estimated by the automated method, in both patients and controls. The contraction frequency 30 min post-meal was significantly lower in patients than in controls, which was correctly shown by both techniques. CONCLUSIONS: A manual technique using ordinary resources of the gamma camera workstation, despite yielding higher figures for the amplitude of gastric contractions, is as accurate as the conventional automated technique of DAS analysis. These findings may favor a more intensive use of DAS coupled to gastric emptying studies, which would provide a more comprehensive assessment of gastric motor function in disease.


Assuntos
Algoritmos , Dispepsia/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão/métodos , Antro Pilórico/diagnóstico por imagem , Adolescente , Adulto , Inteligência Artificial , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Cintilografia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
19.
Fisioter. pesqui ; 14(1): 22-28, jan.-abr. 2007. tab, ilus
Artigo em Português | LILACS | ID: lil-450880

RESUMO

Com o crescente aumento da velocidade e ritmo das atividades laborais, o trabalhador atual sofre maior sobrecarga nas estruturas musculotendíneas.Visando a recuperação dessas estruturas e a prevenção de lesões ocupacionais...


Labour activities increasing speed and rhythm have led to overcharge on workers' muscle-tendon structures. Aiming at recovering such structures and preventing occupational lesions, some companies...


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Pressão Positiva Contínua nas Vias Aéreas , Capacidade Inspiratória , Fatores Etários , Sexo
20.
Physiol Meas ; 27(9): 769-76, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16868344

RESUMO

The distribution of intragastric contents has been studied using operator-dependent methods. We devised an automated technique for determining post-prandial intragastric distribution of radiolabeled meals, based on the calculation of the 'center of activity' (CA) of the radioactivity contained in the stomach in any given scintigraphic image. Twelve healthy volunteers and eleven functional dyspepsia (FD) patients ingested a liquid meal (320 mL, 450 kcal) labeled with (99m)Technetium-phytate. Images of the stomach were acquired every 5-10 min for 2 h, and counted to determine the percentage of total activity retained in the upper half of the stomach, as visually delineated. Each image was then processed using an algorithm for calculating a CA value representing the average of image-forming points corrected by pixel number. The relative CA position along the main longitudinal axis of the stomach, as defined by a digital 'skeletonizing' process, was expressed in a '0 to 1' scale. In the FD patients, the average of all CA determinations was significantly higher than in the controls (0.56, 0.30-0.80 versus 0.48, 0.33-0.68, p < 0.05) and correlated significantly with proximal stomach retention values assessed by a visual method (R = -0.64, p < 0.001). Assessing post-prandial intragastric distribution by a novel automated method is feasible and yields reliable data, while being much less operator dependent.


Assuntos
Esvaziamento Gástrico/fisiologia , Conteúdo Gastrointestinal/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Compostos de Organotecnécio , Ácido Fítico , Período Pós-Prandial/fisiologia , Estômago/diagnóstico por imagem , Estômago/fisiologia , Adulto , Algoritmos , Feminino , Humanos , Masculino , Compostos de Organotecnécio/farmacocinética , Ácido Fítico/farmacocinética , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/farmacocinética
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