89 resultados para DROP-OUTS
Resumo:
Recent studies revealed that vasopressinergic neurons have a high content of cys-leukotriene C(4) (LTC(4)) synthase, a critical enzyme in cys-leukotriene synthesis that may play a role in regulating vasopressin secretion. This study investigates the role of this enzyme in arginine vasopressin (AVP) release during experimentally induced sepsis. Male Wistar rats received an i.c.v. injection of 3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2, 2-dimethylpropanoic acid (MK-886) (1.0 mu g/kg), a leukotrienes (LTs) synthesis inhibitor, or vehicle, 1 h before cecal ligation and puncture (CLP) or sham operation. In one group of animals the survival rate was monitored for 3 days. In another group, the animals were decapitated at 0, 4, 6, 18 and 24 h after CLP or sham operation, and blood was collected for hematocrit, serum sodium and nitrate, plasma osmolality, protein and AVP determination. A third group was used for blood pressure measurements. The neurohypophysis was removed for quantification of AVP content, and the hypothalamus was dissected for LTC4 synthase analysis by Western blot. Mortality after CLP was reduced by the central administration of MK-886. The increase in plasma AVP levels and hypothalamus LTC4 synthase content in the initial phase of sepsis was blocked, whereas the decrease in neurohypophyseal AVP content was partially reversed. Also the blood pressure drop was abolished in this phase. The increase of serum nitric oxide and hematocrit was reduced, and the decrease in plasma protein and osmolality was not affected by the LTs blocker. In the final phase of sepsis, the plasma AVID level and the hypothalamic LTC4 synthase content were at basal levels. The central administration of MK-886 increased the hypothalamic LTC4 synthase content but did not alter the plasma and neurohypophysis AVID levels observed, or the blood pressure during this phase. These results suggest that the central LTs are involved in the vasopressin release observed during sepsis. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.
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Cyrtopodium includes similar to 42 species, among which is Cyrtopodium polyphyllum (Vell.) Pabst ex F. Barros that occurs in a rainforest in south-eastern Brazil. Its non-rewarding flowers, which attract Centridini bees by deceit, are rain-assisted self-pollinated, a phenomenon rarely found in orchids and other plant families. In addition, self-pollination has never been reported in Cyrtopodiinae and data on the pollination of South American orchids are scarce. Flowers were observed at different times of the day, on both sunny and rainy days, to record floral morphology, visitors and the effects of rainfall on flowers. On rainy days, water accumulates on the stigma and dissolves the adhesive substance of the stigmatic surface. A viscous drop thus forms, which contacts the pollinarium. When evaporation makes the viscous drop shrink, the drop moves the pollinarium with the anther onto the stigmatic surface and promotes self-pollination. Fruit set in natural habitat was low, with 2.4% at one study site, where a similar value (2.2%) was recorded in flowers self-pollinated by rain. In C. polyphyllum, facultative self-pollination assisted by rain is thus an important strategy that guarantees fruit set when pollinator`s visits are scarce, which is common in species pollinated by deceit.
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In this work we report the interaction effects of the local anesthetic dibucaine (DBC) with lipid patches in model membranes by Atomic Force Microscopy (AFM). Supported lipid bilayers (egg phosphatidylcholine, EPC and dimyristoylphosphatidylcholine, DMPQ were prepared by fusion of unilamellar vesicles on mica and imaged in aqueous media. The AFM images show irregularly distributed and sized EPC patches on mica. On the other hand DMPC formation presents extensive bilayer regions on top of which multibilayer patches are formed. In the presence of DBC we observed a progressive disruption of these patches, but for DMPC bilayers this process occurred more slowly than for EPC. In both cases, phase images show the formation of small structures on the bilayer surface suggesting an effect on the elastic properties of the bilayers when DBC is present. Dynamic surface tension and dilatational surface elasticity measurements of EPC and DMPC monolayers in the presence of DBC by the pendant drop technique were also performed, in order to elucidate these results. The curve of lipid monolayer elasticity versus DBC concentration, for both EPC and DMPC cases, shows a maximum for the surface elasticity modulus at the same concentration where we observed the disruption of the bilayer by AFM. Our results suggest that changes in the local curvature of the bilayer induced by DBC could explain the anesthetic action in membranes. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Bovine testicular hyalurphidase (BT-HAase), a tetrameric enzyme responsible for randomly hyaluronic acid, catalytic hydrolysis, was successfully immobilized on Langmuir- Blodgett films prepared with the sodium salt of dihexadacylphosphoric acid, (DHP-Zn(II)) ending with dipalmitoylphosphatidylcholine, DPPC. Data of protein, adsorption at the air-liquid interface by means of pendant drop shipe analysis and interaction of the protein with Langmuir monolayers of DPPC, using a Langmuir trough, have provided information. about the conditions to be used in the protein immobilization. The dynamic surface pressure curves obtained from pendant drop experiments for the enzyme in buffer solutions indicate that, within the range of concentration investigated in this study, the enzyme exhibits the largest induction time at 5 mu g L(-1) attributed to diffusion processes. Nevertheless, it seems that, at this concentration, the most probable conformation should be the one which occupies the smallest area at pi -> 0. The surface pressure (pi) area curves obtained for BT-HAase and mixed DPPC- BT-HAase monolayers reveal the presence of the enzyme at the air-lipid interface up to 45 mN m(-1). Tests of enzymatic activity, using hyaluronic acid, HA, as the substrate, showed an increase of activity compared to the homogeneous medium. A simplified model of protein insertion into the lipid matrix is used to explain the obtained results.
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This study aimed to elucidate electrophysiological and cortical mechanisms involved in anticipatory actions when 23 healthy right-handed subjects had to catch a free falling object by qEEG gamma-band (30-100 Hz). It is involved in cognitive processes, memory, spatial/temporal and proprioceptive factors. Our hypothesis is that an increase in gamma coherence in frontal areas will be observed during moment preceding ball drop, due to their involvement in attention, planning, selection of movements, preparation and voluntary control of action and in central areas during moment after ball drop, due to their involvement in motor preparation, perception and execution of movement. However, through a paired t-test, we found an increase in gamma coherence for F3-F4 electrode pair during moment preceding ball drop and confirmed our hypothesis for C3-C4 electrode pair. We conclude that gamma plays an important role in reflecting binding of several brain areas in a complex motor task as observed in our results. Moreover, for selection of movements, preparation and voluntary control of action, motor preparation, perception and execution of movement, the integration of somatosensory and visual information is mandatory. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
Resumo:
Purpose: We evaluated the somatic and autonomic innervation of the pelvic floor and rhabdosphincter before and after nerve sparing radical retropubic prostatectomy using neurophysiological tests and correlated findings with clinical parameters and urinary continence. Materials and Methods: From February 2003 to October 2005, 46 patients with prostate cancer were enrolled in a controlled, prospective study. Patients were evaluated before and 6 months after nerve sparing radical retropubic prostatectomy using the UCLA-PCI urinary function domain and neurophysiological tests, including somatosensory evoked potential, and the pudendo-urethral, pudendo-anal and urethro-anal reflexes. Clinical parameters and urinary continence were correlated with afferent and efferent innervation of the membranous urethra and pelvic floor. We used strict criteria to define urinary continence as complete dryness with no leakage at all, not requiring any pads or diapers and with a UCLA-PCI score of 500. Patients with a sporadic drop of leakage, requiring up to 1 pad daily, were defined as having occasional urinary leakage. Results: Two patients were excluded from study due to urethral stricture postoperatively. We evaluated 44 patients within 6 months after surgery. The pudendo-anal and pudendo-urethral reflexes were unchanged postoperatively (p = 0.93 and 0.09, respectively), demonstrating that afferent and efferent pudendal innervation to this pelvic region was not affected by the surgery. Autonomic afferent denervation of the membranous urethral mucosa was found in 34 patients (77.3%), as demonstrated by a postoperative increase in the urethro-anal reflex sensory threshold and urethro-anal reflex latency (p<0.001 and 0.0007, respectively). Six of the 44 patients used pads. One patient with more severe leakage required 3 pads daily and 23 showed urinary leakage, including 5 who needed 1 pad per day and 18 who did not wear pads. Afferent autonomic denervation at the membranous urethral mucosa was found in 91.7% of patients with urinary leakage. Of 10 patients with preserved urethro-anal reflex latency 80% were continent. Conclusions: Sensory and motor pudendal innervation to this specific pelvic region did not change after nerve sparing radical retropubic prostatectomy. Significant autonomic afferent denervation of the membranous urethral mucosa was present in most patients postoperatively. Impaired membranous urethral sensitivity seemed to be associated with urinary incontinence, particularly in patients with occasional urinary leakage. Damage to the afferent autonomic innervation may have a role in the continence mechanism after nerve sparing radical retropubic prostatectomy.
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Background: Endoscopic sclerotherapy (ES) has been the standard treatment for children with idiopathic extrahepatic portal vein obstruction (EHPVO). Portosystemic shunts are indicated when variceal bleeding cannot be controlled by ES. Recently, mesenteric left portal vein bypass was indicated as a surgical intervention and preventative measure for hepatic dysfunction in children with long-term EHPVO. Nevertheless, there is a lack Of published data confirming the extent of hepatic dysfunction, hypersplenism, and physical development in children with long-term follow-up. Method: We retrospectively verified the long-term outcomes in 82 children with EHPVO treated with ES protocol, focusing on mortality, control of bleeding, hypersplenism, and consequent hepatic dysfunction. Results: Of the children, 56% were free from bleeding after the initiation of ES. The most frequent cause of rebleeding was gastric varices (30%). Four patients had recurrent bleeding from esophageal varices (4.6%). Four patients underwent surgery as a consequence of uncontrolled gastric varices. There were no deaths. Most patients showed good physical development. We observed a mild but statistically significant drop in factor V motion, as well as leukocyte and platelet count. Conclusion: Endoscopic sclerotherapy is an efficient treatment for children with EHPVO. The incidence of rebleeding is low, and there was no mortality. Children develop mild liver dysfunction and hypersplenism with long-term follow-up. Only a few patients manifest symptoms of hypersplenism, portal biliopathy, or liver dysfunction before adolescence. (C) 2009 Elsevier Inc. All rights reserved.
Resumo:
The study aimed to elucidate electrophysiological and cortical mechanisms involved in anticipatory actions when healthy subjects had to catch balls in free drop. Specific alpha absolute power changes were measured in quantitative electroencephalography (qEEG). Our hypothesis is that during the preparation of motoraction (i.e.. 2 s before the ball drops) integration occurs among the left medial frontal, left primary somatomotor and left posterior parietal cortices, showing a differentiated activity involving expectation, planning and preparedness. We contend that in right-handers, the left hemisphere takes on a dominant role for the regulation of motor behavior. The sample was composed of 23 healthy right handed subjects (13 men and 10 women), with ages varying between 25 and 40 years old (32.5 +/- 7.5), absence of mental and physical illness. The experiment consisted of a task of catching balls with the right hard in free drop. The three-way ANOVA analysis demonstrated all interaction between moment and position in left-medial frontal cortex (F3 electrode), somatomotor cortex (C3 electrode) and posterior parietal cortex (P3 electrode: p < 0.05). Summarizing, the experimental task enabled the observation of integration among frontal, central and parietal regions. This integration appears to be more predominant in expectation, planning and motor preparation.
Resumo:
The study aimed to elucidate electrophysiological and cortical mechanisms involved in anticipatory actions when healthy subjects had to catch balls in free drop; specifically through quantitative electroencephalography (qEEG) alpha absolute power changes. Our hypothesis is that during the preparation of motor action (i.e., 2 s before ball`s drop) occurred integration among left medial frontal, left primary somatomotor and left posterior parietal cortices, showing a differentiated activity involving expectation, planning and preparedness. This hypothesis supports a lateralization of motor function. Although we contend that in right-handers the left hemisphere takes on a dominant role for the regulation of motor behavior. The sample was composed of 23 healthy subjects (13 male and 10 female), right handed, with ages varying between 25 and 40 years old (32.5 +/- 7.5), absence of mental and physical illness, right handed, and do not make use of any psychoactive or psychotropic substance at the time of the study. The experiment consisted of a task of catching balls in free drop. The three-way ANOVA analysis demonstrated an interaction between moment and position in left medial frontal cortex (F3 electrode), somatomotor cortex (C3 electrode) and posterior parietal cortex (P3 electrode: p < 0.001). Summarizing, through experimental task employed, it was possible to observe integration among frontal, central and parietal regions. This integration appears to be more predominant in expectation, planning and motor preparation. In this way, it established an absolute predominance of this mechanism under the left hemisphere. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
Resumo:
Objective: To compare the triggering performance of mid-level ICU mechanical ventilators with a standard ICU mechanical ventilator. Design: Experimental bench study. Setting: The respiratory care laboratory of a university-affiliated teaching hospital. Subject: A computerized mechanical lung model, the IngMar ASL5000. Interventions: Ten mid-level ICU ventilators were compared to an ICU ventilator at two levels of lung model effort, three combinations of respiratory mechanics (normal, COPD and ARDS) and two modes of ventilation, volume and pressure assist/control. A total of 12 conditions were compared. Measurements and main results: Performance varied widely among ventilators. Mean inspiratory trigger time was < 100 ms for only half of the tested ventilators. The mean inspiratory delay time (time from initiation of the breath to return of airway pressure to baseline) was longer than that for the ICU ventilator for all tested ventilators except one. The pressure drop during triggering (Ptrig) was comparable with that of the ICU ventilator for only two ventilators. Expiratory Settling Time (time for pressure to return to baseline) had the greatest variability among ventilators. Conclusions: Triggering differences among these mid-level ICU ventilators and with the ICU ventilator were identified. Some of these ventilators had a much poorer triggering response with high inspiratory effort than the ICU ventilator. These ventilators do not perform as well as ICU ventilators in patients with high ventilatory demand.
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The Sciatic Functional Index (SFI) is a quite useful tool for the evaluation of functional recovery of the sciatic nerve of rats in a number of experimental injuries and treatments. Although it is an objective method, it depends on the examiner`s ability to adequately recognize and mark the previously established footprint key points, which is an entirely subjective step, thus potentially interfering with the calculations according to the mathematical formulae proposed by different authors. Thus, an interpersonal evaluation of the reproducibility of an SFI computer-aided method was carried out here to study data variability. A severe crush injury was produced on a 5 mm-long segment of the right sciatic nerve of 20 Wistar rats (a 5000 g load directly applied for 10 min) and the SH was measured by four different examiners (an experienced one and three newcomers) preoperatively and at weekly intervals from the 1st to the 8th postoperative week. Three measurements were made for each print and the average was calculated and used for statistical analysis. The results showed that interpersonal correlation was high (0.82) in the 3rd, 4th, 5th, 7th and 8th weeks, with an unexpected but significant (p < 0.01) drop in the 6th week. There was virtually no interpersonal correlation (correlation index close to 0) on the 1st and 2nd weeks, a period during which the variability between animals and examiners (p =0.24 and 0.32, respectively) was similar, certainly due to a poor definition of the footprints. The authors conclude that the SFI method studied here is only reliable from the 3rd week on after a severe lesion of the sciatic nerve of rats. (C) 2008 Elsevier B.V. All rights reserved.
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Wood-dwelling termites are characterized by an extremely high and unique developmental flexibility that allows workers, which are immatures, to explore all caste options. The endocrine signatures underlying this flexibility are only vaguely understood. We determined juvenile hormone (JH) and ecdysteroid hemolymph titers during postembryonic development and in terminal instars of the drywood termite Cryptotermes secundus using field and laboratory colonies. Postembryonic development is characterized by a drop in JH titers at the transition from larval (individuals without wing buds) to nymphal (individuals with wing buds) instars. JH titers were low in winged sexuals and reproducing primary reproductives (< 200 pg/mu l) but were by an order of magnitude higher in neotenic replacement reproductives. The unique regressive molts of termites seem to be characterized by elevated JH titers, compared with progressive or stationary molts. Ecdysteroid titers were generally low in nymphal instars and in primary reproductives (< 50 pg/mu l). It was only during the third and fourth nymphal instars and in winged sexuals where some individuals showed elevated ecdysteroid titers. These results are the most comprehensive endocrinological data set available for any lower termite, with the potential to serve as baseline for understanding the extreme developmental flexibility underlying the evolution of social life in termites.
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The insulin/insulin-like signaling (IIS) pathway is an evolutionarily conserved module in the control of body size and correlated organ growth in metazoans. In the highly eusocial bees, the caste phenotypes differ not only in size and several structural features but also in individual fitness and life history. We investigated the developmental expression profiles of genes encoding the two insulin-like peptides (AmILP-1 and AmILP-2) and the two insulin receptors (AmInR-1 and AmInR-2) predicted in the honey bee genome. Quantitative PCR analysis for queen and worker larvae in critical stages of caste development showed that AmILP-2 is the predominantly transcribed ILP in both castes, with higher expression in workers than in queens. Expression of both InR genes sharply declined in fourth instar queen larvae, but showed little modulation in workers. On first sight, these findings are non-intuitive, considering the higher growth rates of queens, but they can be interpreted as possibly antagonistic crosstalk between the IIS module and juvenile hormone. Analyzing AmInR-1 and AmInR-2 expression in ovaries of queen and worker larvae revealed low transcript levels in queens and a sharp drop in AmInR-2 expression in fifth instar worker larvae, indicating relative independence in tissue-specific versus overall IIS pathway activity. (C) 2008 Elsevier Ltd. All rights reserved.
Resumo:
The present study was designed to assess the hypothesis that dexamethasone (DEX) through the control of nitric oxide (NO) synthesis could regulate the release of vasopressin (AVP), which plays an important role in the regulation of arterial pressure and plasma osmolality. Endotoxemic shock was induced by intravenous (i.v.) injection of 1.5 mg/kg lipopolisaccharide (LPS) in male Wistar rats weighing 250-300 g. After LPS administration, a group of animals were treated with DEX (1.0 mg/kg of body weight), whereas saline-injected rats served as controls. The LPS administration induced a significant decrease in mean arterial pressure (MAP) with a concomitant increase in heart rate (HR) (Delta VMAP: -16.1 +/- 4.2 mm Hg; Delta VHR: 47.3 +/- 8.1 bpm). An increase in plasma AVP concentration occurred and was present for 2 h after LPS administration (11.1 +/- 0.9 pg/mL) returning close to basal levels thereafter and remaining unchanged until the end of the experiment. When LPS was combined with i.v. administration of a low dose of DEX, we observed an attenuation in the drop of MAP (Delta VMAP: -2.2 +/- 1.9 mm Hg) and a decrease in NO plasma concentration [NO] after LPS administration (1098.1 +/- 68.1 mu M) compared to [NO] after DEX administration (523.4 +/- 75.2 mu M). However, this attenuation in the drop of MAP was accompanied by a decrease in AVP plasma concentration (3.7 +/- 0.4 pg/mL). These data suggest that AVP does not participate in the recovery of MAP when DEX is administered in this endotoxemic shock model. (C) 2008 Elsevier B.V. All rights reserved.
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Purpose: To compare the level of sedation of oral administration of diazepam or midazolam associated or not with clonidine and their effects on upper eyelid margin position, heart rate, arterial pressure, and oxygen saturation. Methods: Seventy consecutive healthy patients American Society of Anesthesiologists (ASA) grade I-II scheduled for lower eyelid blepharoplasty were randomized into 4 groups according to the oral sedative agent used (group 1, diazepam 10 mg; group 2, diazepam 10 mg plus clonidine 0.15 mg; group 3, midazolam 15 mg; group 4, midazolam plus clonidine 0.15 mg). For all patients, the midpupil-to-upper eyelid margin distance, the heart rate, systolic and diastolic blood pressure, and oxygen saturation were recorded before and 1 hour after the administration of oral medication. The level of sedation at the time of surgery was measured with the Michigan University scale. Results: The depth of sedation was significantly more pronounced with midazolam (median score = 2) than with diazepam (median score = 1). Clonidine slightly increased the level of sedation of both diazepam and midazolam. The diastolic arterial blood pressure drop with midazolam associated or not with clonidine was significantly greater than with diazepam. The mean upper eyelid margin position shift (-1.42 mm) verified when clonidine was associated with midazolam was also significantly greater than with diazepam. Discussion: Oral sedation with diazepam or midazolam associated or not with clonidine is safe for ASA grade I-II patients. The systemic effects of diazepam and midazolam were small and very similar. The sedation induced by midazolam was clearly greater than that induced by diazepam. However, this higher level of sedation was accompanied by a more important shift in upper eyelid margin position.