Relação dose-dependente do uso crônico de fenitoína e atrofia cerebelar em pacientes com epilepsia

The chronic treatment with phenytoin or the acute intoxication by this drug may cause permanent cerebellar injury with atrophy of cerebellum vermis and hemispheres, which can be detected by neuroimaging studies. The aim of the present study was to investigate the correlation between the dosage and duration of treatment with phenytoin and the occurrence of cerebellar atrophy. Sixty-six patients were studied and had their tomographies analyzed for cerebellar atrophy. Of the 66 patients studied, 18 had moderate/severe atrophy, 15 had mild atrophy and 33 were considered to be normal. The patients with moderate/severe atrophy were those with higher exposure to phenytoin (longer duration of treatment and higher total dosage) showing statistically significant difference when compared to patients with mild atrophy or without atrophy (p=0.02). Further, the patients with moderate/severe atrophy had serum levels of phenytoin statistically higher than those of patients with mild atrophy or without atrophy (p = 0.008). There was no association between other antiepileptic drugs dosage or duration of treatment and degree of cerebellar atrophy. We also found that older patients had cerebellar atrophy more frequently, indicating that age or duration of the seizure disorder may also be important in the determination of cerebellar degeneration in these patients. We conclude that although there is a possibility that repeated seizures contribute to cerebellar damage, long term exposure to phenytoin, particularly in high doses and toxic serum levels, cause cerebellar atrophy.

Uso de membranas de Nafion para a construção de sensores ópticos para medidas de pH

The behaviour of Nafion® polymeric membranes containing acid-base dyes, bromothymol blue (BB) and methyl violet (MV), were studied aiming at constructing an optical sensor for pH measurement. BB revealed to be inadequate for developing sensing phases due to the electrostatic repulsion between negative groups of their molecules and the negative charge of the sulfonate group of the Nafion®, which causes leaching of the dye from the membrane. On the other hand, MV showed to be suitable due to the presence of positive groups in its structure. The membrane prepared from a methanolic solution whose Nafion®/dye molar ratio was 20 presented the best analytical properties, changing its color from green to violet in the pH range from 0.6 to 3.0. The membrane can be prepared with good reproducibility, presenting durability of ca. 6 months and response time of 22 s, making possible its use for pH determination in flow analysis systems.

Novos sorventes baseados em poli (metiloctilsiloxano) sobre sílica para uso em extração em fase sólida

This paper presents an easy and practical procedure to obtain silica-based C-8 type sorbents for use in solid-phase extraction. The materials are prepared by depositing poly(methyloctylsiloxane), PMOS, on the silica support. Two different treatments for immobilization were used: thermal treatment or gamma irradiation. Suitable recoveries were obtained after pre-concentration of dilute solutions, at the ng/L level, of a mixture of pesticides, indicating the good performance of the materials.

Possibilidades e limitações no uso da temperatura em cromatografia líquida de fase reversa

High-temperature liquid chromatography (HTLC) is a technique that presents a series of advantages in liquid phase separations, such as: reduced analysis time, reduced pressure drop, reduced asymmetry factors, modified retentions, controlled selectivities, better efficiencies and improved detectivities, as well as permitting green chromatography. The practical limitations that relate to instrumentation and to stationary phase instability are being resolved and this technique is now ready to be applied for routine determinations.

Uso de perfis cromatográficos de voláteis de cafés arábicas torrados para a diferenciação das amostras segundo o sabor, o aroma e a qualidade global da bebida

In this work, the volatile chromatographic profiles of roasted Arabica coffees, previously analyzed for their sensorial attributes, were explored by principal component analysis. The volatile extraction technique used was the solid phase microextraction. The correlation optimized warping algorithm was used to align the gas chromatographic profiles. Fifty four compounds were found to be related to the sensorial attributes investigated. The volatiles pyrrole, 1-methyl-pyrrole, cyclopentanone, dihydro-2-methyl-3-furanone, furfural, 2-ethyl-5-methyl-pyrazine, 2-etenyl-n-methyl-pyrazine, 5-methyl-2-propionyl-furan compounds were important for the differentiation of coffee beverage according to the flavour, cleanliness and overall quality. Two figures of merit, sensitivity and specificity (or selectivity), were used to interpret the sensory attributes studied.

Determinação da densidade de corrente de corrosão em meios de baixa condutividade: uso de microeletrodos para minimizar a queda ôhmica

The gravimetric and electrochemical tests are the most common techniques used in determining the corrosion rate. However, the use of electrochemical polarization is limited to electrolytes with sufficient conductivity for which Tafel curves are linear. In this study, we investigated a technique in which working microelectrodes of AISI 1020 steel were used to obtain the Tafel curves in diesel oil. The strategy was to reduce the electrode area and hence the ohmic drop. The diameter of the microelectrode was reduced to a value where the compensation of the Tafel curves became unnecessary. The results showed that for electrodes with diameters below 50 μm, the ohmic drop tends to a minimum and independent of the microelectrode diameter.

Avaliação de tipos de ventilação em maternidade de suínos

Livestock facilities, where animals carry their productive cycle, must have as main characteristic, the control of influence over climatic factors on animals. The environment variations can be controlled through the use of different ventilation systems. The objective of this research was to evaluate the influence of different environment conditioning systems on swine nursery. Three treatments have been tested: natural ventilation, cooled ventilation and forced ventilation. The climatic parameters evaluated were: air temperature, relative humidity and black globe temperature. The physiological parameters analyzed were: respiratory frequency and back fat thickness. Number of born alive piglets, average weight at weaning and number of weaned piglets were also evaluated parameters. The use of cooled ventilation systems were able to decreased animal's air temperature and respiratory frequency, and the black globe temperature and humidity index (WBGT) and the radiating thermal load (RTL).

Avaliação do uso de identificadores eletrônicos em suínos

Nowadays the consumer market demands a gradually increase in the products' quality control. The manual control that exits, used in animal production, shows ineficiency in warrating an increasing percentual of the desirable quality, so this can only be reached when an effective animal tracebility system is applied, from birth to slaughter. Individual electronic identification presents high importance in this focus, providing information recorded directly from the animal. Electronic traceability uses electronic devices that emit a signal activated by a fixed reader placed where it is needed to record a certain event, or uses a manual reader which allows a higher independence of the operator. Knowing the importance of the electronic identification as a tool for applying traceability in animal production, this research had as objective to evaluate the use of transponders in order to garantee the manual reading as well as the fixed antenna reading. The following implant places were analized in piglet, just after their birth: 1) forehead, 2) external ear lobule, 3) the posterior auricular base, and 4) a transponder inserted in a earing implanted in the ear lobule. The factors of skin damage and migration were analized, as well as the reading efficiency. It was found that the best implant place was the posterior ear base.

Uso de redes neurais artificiais na identificação de vocalização de suínos

Animal welfare has been an important research topic in animal production mainly in its ways of assessment. Vocalization is found to be an interesting tool for evaluating welfare as it provides data in a non-invasive way as well as it allows easy automation of process. The present research had as objective the implementation of an algorithm based on artificial neural network that had the potential of identifying vocalization related to welfare pattern indicatives. The research was done in two parts, the first was the development of the algorithm, and the second its validation with data from the field. Previous records allowed the development of the algorithm from behaviors observed in sows housed in farrowing cages. Matlab® software was used for implementing the network. It was selected a retropropagation gradient algorithm for training the network with the following stop criteria: maximum of 5,000 interactions or error quadratic addition smaller than 0.1. Validation was done with sows and piglets housed in commercial farm. Among the usual behaviors the ones that deserved enhancement were: the feed dispute at farrowing and the eventual risk of involuntary aggression between the piglets or between those and the sow. The algorithm was able to identify through the noise intensity the inherent risk situation of piglets welfare reduction.

Ensino de Gramáticas: descrição e uso

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Projeto de caixa de madeira para manga (Mangifera Indica L.)

Losses of horticulture product in Brazil are significant and among the main causes are the use of inappropriate boxes and the absence of a cold chain. A project for boxes is proposed, based on computer simulations, optimization and experimental validation, trying to minimize the amount of wood associated with structural and ergonomic aspects and the effective area of the openings. Three box prototypes were designed and built using straight laths with different configurations and areas of openings (54% and 36%). The cooling efficiency of Tommy Atkins mango (Mangifera Indica L.) was evaluated by determining the cooling time for fruit packed in the wood models and packed in the commercially used cardboard boxes, submitted to cooling in a forced-air system, at a temperature of 6ºC and average relative humidity of 85.4±2.1%. The Finite Element Method was applied, for the dimensioning and structural optimization of the model with the best behavior in relation to cooling. All wooden boxes with fruit underwent vibration testing for two hours (20 Hz). There was no significant difference in average cooling time in the wooden boxes (36.08±1.44 min); however, the difference was significant in comparison to the cardboard boxes (82.63±29.64 min). In the model chosen for structural optimization (36% effective area of openings and two side laths), the reduction in total volume of material was 60% and 83% in the cross section of the columns. There was no indication of mechanical damage in the fruit after undergoing the vibration test. Computer simulations and structural study may be used as a support tool for developing projects for boxes, with geometric, ergonomic and thermal criteria.

O uso da mitomicina C em cirurgia combinada

Purpose: To analyze the efficacy and safety of intraope-rative mitomycin C (MMC) in combined procedures (extra-capsular cataract extraction + trabeculectomy). Methods: Twenty-four patients were randomized to either MMC (0.5 mg/ml) (n = 14) or saline solution (n = 10) for 3 minutes during the combined procedure. Results: Twelve months after surgery, mean IOP in the MMC group (13.2 ± 2.9 mmHg) was significantly lower than in the control group (16.3 ± 3.9 mmHg) (p = 0.02). The mean number of medications used during the 12-month follow-up in the control group (1.33 ± 0.5) was significantly higher than in the MMC-treated group (0.5 ± 0.5) (p = 0.005). Life table analysis showed a significantly higher probability of IOP control in the MMC group than in the control group (p < 0.01). Conclusions: Intraoperative MMC is safe and effective in pro-moting a better IOP control and reducing the need for postoperative antiglaucoma medications. We suggest intraope-rative MMC to be routinely employed in combined procedures.

Efeitos da constrição pupilar na perimetria de freqüência dupla em olhos normais

Purpose: To study the effects of pupillary constriction on frequency doubling perimetry in a group of normal subjects. Methods: Eighteen healthy volunteers participated in the study. Only one eye per patient (right eye) underwent frequency doubling perimetry (Full Threshold C-20 strategy). For the second session, one drop of 2% pilocarpine was administered to the volunteers' right eye and the examination was repeated after 60 minutes. Results: Sixty minutes after administration of 2% pilocarpine, there was a significant reduction of the pupillary diameter from 4.22 ± 0.17 mm to 1.55 ± 0.51 mm (p<0.05). There was a significant reduction of the mean retinal sensibility after pupillary constriction. The threshold sensitivity of the central 5º worsened by 5.67 ± 2.49 dB; the area between 2.5º and 10º worsened by 4.49 ± 2.73 dB; and the area between 10º and 20º worsened by 5.10 ± 3.55 dB (p<0.01). A reduction of 4.06 ± 2.67 dB was observed in the mean deviation, as well as an increase of 0.64 ± 0.94 dB in the pattern standard deviation (p<0.01). No differences were observed regarding the number of fixation losses, false-positive and false-negatives responses, and duration of the examination. Conclusion: Changes in pupillary diameter may produce significant declines in threshold sensitivities of the 20º visual field tested by frequency doubling perimetry. These results suggest that is important to maintain a constant pupillary diameter in seriate examinations.

Curva de aprendizado e flutuações a curto e longo prazos com perimetria de freqüência dupla (FDT)

OBJECTIVE: To evaluate the learning effect, short-term fluctuation and long-term fluctuation in healthy subjects undergoing frequency doubling perimetry (FDP). METHODS: Twenty healthy young subjects underwent FDT (program N30, full threshold) in one eye (right). Each subject was tested once in the first three sessions and three times in the fourth session. Both short- and long-term fluctuations were studied as the average fluctuation of all the tested points or as a point-to-point fluctuation. To study the learning effect, the MDs values of the first session were compared to the second, third and fourth sessions. RESULTS: In the short-term analysis (3 examination done in the last session), the total mean sensitivity was 31.91 ± 1.20 dB and the mean MD and PSD were 0.84 ± 1.85 and 3.73 ± 1.55 dB, respectively. The average short-term fluctuation was 1.72 ± 0.38 dB. When the four examination, performed at different visits, were compared, the average mean sensitivity of all sessions and the average long-term fluctuation were 31.75 ± 1.11 and 2.16 ± 0.26 dB, respectively. The MD averages of the first, second, third and fourth tests were 0.11 ± 2.14 dB, 0.47 ± 1.64 dB, 1.16 ± 1.62 dB and 0.98 ± 1.92 dB respectively. The MD difference between the first and the third and between the first and the fourth examinations were statistically significant (p<0.05). CONCLUSION: The threshold sensitivity detected by FDP is influenced by both short- and long-term fluctuations. We observed a mild learning effect that shoud be taken into account whenever a patient undergoes this test for the first time.

Tratamento clínico da epilepsia resistente

The authors analysed 34 cases of resistant epilepsy (20 males and 14 females, mean age 23 years), treated clinically between February/1984 and May/1986. The patients underwent neurological, neuropsychological, psychological, psychiatric, cerebrospinal fluid, electroencephalographic, tomographic and/or angiographic examination. Most of the patients had complex partial seizures. The etiology was unknown in 19 patients (55.8%), probable neurocysticercosis in 6, perinatal hypoxia in 5, delivery trauma in 3 and probable sequelae of encephalitis in 2 patients. There was a clear past history of infantile febrile convulsion in 2 patients. Most patients received carbamazepine (mean dose 24.5 mg/kg/day), phenytoin (5 mg/kg and valproic acid (28 mg/kg) as monotherapy or in association. Twenty-two patients (64.7%) had more than 80% decrease of the seizure frequency. Nine resistant epilepsy-cases (24.5%) were evaluated as candidates for surgical therapy. The authors concluded that the resistant epilepsy is best managed by a specialised, multidisciplinary team, and pointed out the need of a correct diagnosis of the seizure type, an adequate drug therapy and a good engagement of the patient and his family in the treatment.