Dental pain in Brazilian preschool children: association with the severity of dental caries and impact on oral health-related quality of life.

PURPOSE: This study aimed to verify the association between dental pain and severity of dental caries (caries morbidity stages) and the impact on oral health-related quality of life (OHRQoL) in preschool children. METHODS: A cross-sectional study with 199 children (2-5 years old) enrolled at preschools in Capão do Leão-RS, Brazil. The self-report of mothers of children with a history of dental pain in the last 6 months and perception of their child's OHRQoL (ECOHIS) were obtained through a structured questionnaire. This questionnaire also collected independent variables. Children's oral examination was performed using the CAST instrument to determine caries morbidity stage. Crude and adjusted Poisson regression analysis was performed. RESULTS: The prevalence of dental pain was 14.57%. The chance of the occurrence of dental pain was higher among children diagnosed in morbidity [Prevalence ratio-PR: 5.29 (95% confidence interval-95% CI 1.91-14.61); p = 0.001] and severe morbidity [RP = 6.12 (95 CI% 2.25-16.64); p < 0.001] stages. Children with dental pain presented higher scores in the total ECOHIS [rate ratio = 7.11 (95% CI 4.55-11.09); p < 0.001] and in all of the domains of this instrument. Furthermore, children with a history of dental trauma [PR = 2.41 (95% CI 1.15-5.04); p < 0.001] and those whose reason for last visit to the dental office was for restorative/endodontic/extraction treatment [PR = 1.29 (95% CI 1.01-6.19); p = 0.049] had a higher prevalence of dental pain. CONCLUSION: A substantial prevalence of dental pain in the last 6 months and negative impact on children's OHRQoL was identified in this sample. Children diagnosed with carious dentin lesions and abscess and fistula were more likely to have dental pain.

Thrombocytopenia in pregnancy, a challenge in the intensive care unit (ICU). / Trombocitopenia en el embarazo, un desafío en la unidad de cuidados intensivos (UCI).

Thrombocytopenia is a common alteration during pregnancy and the multiple possible aetiologies make the differential diagnosis challenging. Physiological changes of pregnancy can mask severe conditions until advanced stages. This case refers to a pregnant woman who presented fever and thrombocytopenia during labour. In the postpartum period she developed rapidly progressive hemodynamic instability requiring admission to the ICU. There was progression to acute kidney injury, persistent thrombocytopenia and platelet dysfunction. The differential diagnosis included DIC in the context of sepsis, PPH and other causes of thrombotic microangiopathies in pregnancy.

Hysteresis and change of transition temperature in thin films of Fe{[Me2Pyrz]3BH}2, a new sublimable spin-crossover molecule.

Thin films of the spin-crossover (SCO) molecule Fe{[Me2Pyrz]3BH}2 (Fe-pyrz) were sublimed on Si/SiO2 and quartz substrates, and their properties investigated by X-ray absorption and photoemission spectroscopies, optical absorption, atomic force microscopy, and superconducting quantum interference device. Contrary to the previously studied Fe(phen)2(NCS)2, the films are not smooth but granular. The thin films qualitatively retain the typical SCO properties of the powder sample (SCO, thermal hysteresis, soft X-ray induced excited spin-state trapping, and light induced excited spin-state trapping) but present intriguing variations even in micrometer-thick films: the transition temperature decreases when the thickness is decreased, and the hysteresis is affected. We explain this behavior in the light of recent studies focusing on the role of surface energy in the thermodynamics of the spin transition in nano-structures. In the high-spin state at room temperature, the films have a large optical gap (∼5 eV), decreasing at thickness below 50 nm, possibly due to film morphology.

Endocrine and metabolic function in male Carioca High-conditioned Freezing rats.

The aim of this study was to characterize Carioca High-conditioned Freezing rats (CHF) regarding their endocrine and metabolic backgrounds. We found an increase in serum corticosterone (CTRL: 96.7 ± 21.65 vs CHF: 292.0 ± 4 0.71 ng/ml) and leptin (CTRL: 9.5 ± 1.51 vs CHF: 19.2 ± 4.32 ng/ml). Serum testosterone (CTRL: 3.3 ± 0.29 vs CHF: 2.0 ± 0.28 ng/ml) and T3 (CTRL: 52.4 ± 2.74 vs CHF: 42.7 ± 2.94 ng/dl) were decreased in the CHF group, but serum TSH and T4 were unaffected. Body weight and food intake were unchanged, nevertheless retroperitoneal fat (CTRL: 2.2 ± 0.24 vs CHF: 4.8 ± 0.64 g) and epididymal fat (CTRL: 2.6 ± 0.20 vs CHF: 4.8 ± 0.37 g) depot weights were around 2-fold higher in CHF animals. BAT weight was similar in both groups. Serum triglycerides (CTRL: 41.4 ± 6.03 vs CHF: 83.2 ± 17.09 mg/dl) and total cholesterol (CTRL: 181.6 ± 5.61 vs CHF: 226.4 ± 13.04 mg/dl) were higher in the CHF group. Fasting glycemia (CTRL: 68.7 ± 3.04 vs CHF: 82.3 ± 2.99 mg/dl) was also higher in the CHF group, however glucose tolerance test response and serum insulin levels were similar between the groups. Oxygen consumption (CTRL: 10.5 ± 0.40 vs CHF: 7.9 ± 0.58 VO2ml/min/kg(0.75)) and BAT D2 activity (CTRL: 0.7 ± 0.17 vs CHF: 0.3 ± 0.04 fmolT4/min/mg ptn) were lower in the CHF group. Our data show that anxiety could impair endocrine and metabolic functions and may contribute to the development of metabolic diseases.

Few-layered graphene-supported palladium as a highly efficient catalyst in oxygen reduction reaction.

New, active and stable catalysts competitive to Pt catalysts are necessary for fuel cell development. Here, we present few-layered graphene-supported Pd, revealing a performance superior to Pt/C and Pd/C ORR (positive half-wave potential shift E(1/2) by 50 mV, approximately one order of magnitude higher area- and mass-normalized current densities, I(area), I(mass), after 2500 cycles). The catalyst preparation is easily scalable, simple, inexpensive and eco-friendly.

Differential expression patterns of N-acetylglucosaminyl transferases and polylactosamines in uterine lesions.

Polylactosamine (polyLacNAc) is a fundamental structure in glycoconjugates and it is expressed in specific cells/tissues associated with the development and carcinogenesis. ß1,3-N-acetylglucosaminyl transferases (ß3GnTs) play an important role in polyLacNAc synthesis, however the roles of these glycosyltransferases and their products in cancer progression are still unclear. In this sense, this work aimed to evaluate differential expression pattern of the N-acetylglucosaminyl transferases and polylactosamines in invasive and premalignant lesions of the uterus cervix. The expression of ß3GnT2 and ß3GnT3 were evaluated in normal (n=10) and uterine cervix lesions (n= 120) malignant (squamous carcinoma - SC) and premalignant (cervical intraepithelial neoplasia - CIN - grades 1, 2 and 3) using immunohistochemistry. Besides, lectin histochemistry with Phytolacca americana lectin (PWM) and Wheat germ agglutinin (WGA) was also carried out to observe the presence of polyLacNAc chains and N-acetylglucosamine (GlcNAc), respectively. The ß3GnT3 was expressed in almost all samples (99%) and ß3GnT2 was higher expressed in disease samples mainly in CIN 3, when compared with normal (P=0.002), CIN 1 (P=0.009) and CIN 2 (P=0.03). The expression of polyLacNAc was higher is SC samples, when compared with normal (P=0.03), CIN 1 (P=0.02) and CIN 3 (P=0.004), and was observed only nuclear expression in nearly 50% of the SC samples, showing a statistically significant when compared with normal (P=0.01), CIN 1 (P=0.002), CIN 2 (P=0.007) and CIN 3 (P=0.04). Deferring from transferases and polyLacNAc chains, GlcNAc (WGA ligand) reveals a gradual staining pattern decrease with the increase of the lesion degree, being more expressed in CIN 1 lesions when compared with normal (P<0.0001), CIN 2 (P<0.0001), SC (P<0.0001) and CIN 3 (P=0.0003). Our data reveals ß3GnT2 and polyLacNAc may be involved in the progression of the pre-malignant lesions of human the uterine cervix. In addition, polyLacNAc expression only in the nucleus can be associated a poor prognostic in uterine lesions.

Resistance of Sugarcane Cultivars to Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae).

The spittlebug Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) is one of the most important pests of the sugarcane crop in Brazil. Despite of its importance, there is currently a lack of information regarding sugarcane cultivars' resistance to the spittlebug. Therefore, our objective was to evaluate the response of sugarcane genotypes to this species. Two experiments were carried out under laboratory conditions using a random block design with treatments in a factorial arrangement of 2 × 13 (experiment 1) and 2 × 12 (experiment 2), with six replicates. The first factor included two levels of infestation (infested and noninfested plants with spittlebugs), while the second consisted of the cultivars. Nymph survival varied from 47.9 to 84.5%, indicating that there are different levels of antibiosis to M. fimbriolata among the tested cultivars. The highest degree of antibiosis was found in cultivars IACSP96-7586 and IACSP96-2008, in which nymph survival was close to 48%. IACSP96-7586 also presented some degree of tolerance, but IACSP96-7569 and IACSP97-6682 stood out as the most tolerant cultivars to the pest, showing the lowest reduction in weight of aboveground biomass. On average, spittlebug infestations caused a significant reduction in relative leaf chlorophyll content and aboveground biomass weight.

First glimpse of the soft x-ray induced excited spin-state trapping effect dynamics on spin cross-over molecules.

The dynamics of the soft x-ray induced excited spin state trapping (SOXIESST) effect of Fe(phen)2(NCS)2 (Fe-phen) powder have been investigated by x-ray absorption spectroscopy (XAS) using the total electron yield method, in a wide temperature range. The low-spin (LS) state is excited into the metastable high-spin (HS) state at a rate that depends on the intensity of the x-ray illumination it receives, and both the temperature and the intensity of the x-ray illumination will affect the maximum HS proportion that is reached. We find that the SOXIESST HS spin state transforms back to the LS state at a rate that is similar to that found for the light induced excited spin state trapping (LIESST) effect. We show that it is possible to use the SOXIESST effect in combination with the LIESST effect to investigate the influence of cooperative behavior on the dynamics of both effects. To investigate the impact of molecular cooperativity, we compare our results on Fe-phen with those obtained for Fe{[Me2Pyrz]3BH}2 (Fe-pyrz) powder, which exhibits a similar thermal transition temperature but with a hysteresis. We find that, while the time constant of the dynamic is identical for both molecules, the SOXIESST effect is less efficient at exciting the HS state in Fe-pyrz than in Fe-phen.

Evaluation of osteoporotic bone structure through synchrotron radiation X-ray microfluorescence images.

The abnormal accumulation or deficiency of trace elements may theoretically impair the formation of bone and contribute to osteoporosis. In this context, the knowledge of major and trace elements is very important in order to clarify many issues regarding diseases of the bone, such as osteoporosis, that remain unresolved. Several kinds of imaging techniques can be useful to access morphology and the minerals present in osteoporotic bones. In this work, synchrotron radiation X-ray microfluorescence was used as an X-ray imaging technique to investigate bone structures. Therefore, this research aims to improve the knowledge about some aspects of bone quality. The measurements were carried out at the Brazilian Synchrotron Laboratory Light Laboratory, in Brazil. A white beam with an energy range of 4-23 keV, a 45 degrees /45 degrees geometry and a capillary optics were used. It was demonstrated that bone quality can and must be evaluated not only by considering the architecture of bones but also by taking into account the concentration and the distribution of minerals. Our results showed that the elemental distributions in bone zones on a micron scale were very helpful to understand functions in those structures.

Effects of aging on thyroidal function and proliferation.

The endocrine system is as affected by aging as are other systems. The effect of aging on the hypothalamus-pituitary-thyroid function is still controversial. Human aging was reported as associated with a decrease in thyrotropin (TSH) secretion, but increased TSH levels in relatively healthy elders are also reported. The main point discussed is whether this increase in the immunoreactive TSH of aged subjects, and related changes in thyroid function, are "physiologic" consequences of aging on the hypothalamus-pituitary-thyroid axis or are induced by non-thyroid illnesses and/or drug use, frequent in the elderly. There are strong evidences of decreased hypothalamus-pituitary-thyroid axis activity as well as decreased thyroxine metabolism (5'-deiodination) in humans, and other mammals. For now, we must consider that the hypothalamus-pituitary-thyroid axis is affected at all three levels by normal aging, and the mild state of "total" hypothyroidism during aging is completed by a reduced response of target cells/tissues to thyroid hormones. Despite the decreased response of the old rat thyroid to TSH there is no decrease in the glands mass. Ras proteins are involved in the transduction of growth factor signals by surface receptors, in thyroid as well as in other tissues, and are key components of downstream signaling through several pathways. Ras activation of Raf, and of extracellular-signal-regulated kinases (ERK) is an important signaling pathway for many Ras effects. Very little is known about the modulation of Ras expression in the aging thyroid. We detected an increase in Ras expression in thyroids of old rats, but the signal transduction by pERK was decreased, suggesting that another RAS-signaling pathway could be activated and responsible for the maintenance of the thyroid volume.

Effects of ageing and pharmacological hypothyroidism on pituitary-thyroid axis of Dutch-Miranda and Wistar rats.

To evaluate the ability of the aged rat pituitary to increase TSH secretion in response to major decreases in serum thyroid hormones, hypothyroidism was induced by methimazole in young and old, male and female, Dutch-Miranda and Wistar rats. Before MMI-treatment there were no differences in serum TSH of young and old rats, but serum T(4) was significantly decreased in aged rats from both genders and strains, while serum T(3) was significantly decreased in aged male rats from both strains, and in old Wistar females. MMI treatment significantly decreased serum T(4) and T(3) in all treated animals, and progressively increased serum TSH in both male and female rats, but the increase was significantly smaller in the elder rats. The pituitary TSH content was higher in Wistar than in Dutch-Miranda rats, of both genders, and was not significantly affected by age. MMI treatment decreased the pituitary TSH in both young and old Dutch-Miranda rats, but in the Wistar strain only the old females had a significant decrease. Our results show that the ability of the pituitary thyrotrophs to increase hormonal secretion in response to decreased levels of thyroid hormones is impaired in the old rat, even when the thyroid hormone levels are dramatically reduced.

Genotoxic evaluation of a vinifera skin extract that present pharmacological activities.

Toxicity of an alcohol-free hydro-alcoholic grape skin extract (GSE) obtained from red grapes Vitis labrusca (Isabel varietal) that present antihypertensive, vasodilator and antioxidant effects was estimated by different bioassays. Using the Salmonella/microsome assay for strains TA97, TA98, TA100 and TA102 no mutagenicity was detected for all tested concentrations (0.1-100 microg/ml), even with metabolization. Nevertheless, cytotoxicity was observed for TA97 and TA102 with and without metabolization and for TA100 with metabolization. The measurement of beta-galactosidase induction in the SOS-chromotest was positive only for Escherichia coli PQ37 when metabolization enzymes were present. Using Balb/c 3T3 fibroblasts, DNA strand breaks induction by GSE was also investigated by the comet assay and no significative difference was detected for treated and no treated DNA for 60 min. Our data suggest that GSE although no mutagenic presents cytotoxic activity.

Effect of the oral contraceptive pill on patients undergoing controlled ovarian hyperstimulation

This is a retrospective analysis of 89 patients who were undergoing controlled ovarian hyperstimulation for in vitro fertilization and embryo transfer in the Fertility Management Unit of the Department of Obstetrics, Gynaecology and Child Health, The University of the West Indies. Twenty-eight patients (Group A), who did not receive oral contraceptive pills prior to controlled ovarian hyperstimulation (COH) were compared with 61 patients in Group B treated with oral contraceptive pills for two months prior to undergoing COH assisted reproduction using the long protocol. The number of follicles, oocytes, estimated oestradiol levels on the day of administration of human chorionic gonadotrophin (hCG), pregnancy rates, miscarriage rates and the incidence of patients who developed ovarian hyperstimulation syndrome (OHSS) were the main outcome measures. The mean age and haematocrit were the same in each group. The number of follicles retrieved tended to be higher in Group A than in Group B (median 8 versus 6, p = 0.06) with significantly more oocytes being retrieved in Group A than Group B (p < 0.05). There were no statistically significant differences between the two groups in oestradiol levels, the proportion of patients with polycystic ovarian disease, the proportion of women who developed ovarian hyper-stimulation syndrome or pregnancy outcomes. There was no difference between the groups in measures of clinical severity of OHSS. In a logistic regression model the significant predictors of OHSS were haematocrit and oestradiol levels. There appeared to be no significant clinical benefit in administering oral contraceptive pills for two months to patients prior to COH

Bradykinin B1 receptor stimulates the proximal tubule Na(+)-ATPase activity through protein kinase C pathway.

Recently, our group described a B1-mediated stimulatory effect of des-Arg(9)-bradykinin (DABK) on the Na(+)-ATPase activity of proximal tubule basolateral membranes (BLM) [Biochim. Biophys. Acta 1431 (1999) 483.]. Data in the present report suggest the participation of a phosphatidylinositol-specific PLC (PI-PLC)/protein kinase C (PKC) pathway as the molecular mechanism of DABK-mediated stimulation of the Na(+)-ATPase activity since (i) 10(-8) M DABK activates PI-PLC activity; (ii) 10(-9) M U73122, a PI-PLC inhibitor, abolishes the effect of 10(-8) M DABK on the Na(+)-ATPase activity; (iii) 10(-8) M DABK increases phosphoprotein formation by 34%. This effect is completely reversed by 10(-7) M calphostin C, an inhibitor of PKC; (iv) 20 ng/ml TPA, an activator of PKC, and 10(-8) M DABK stimulate the Na(+)-ATPase activity in a similar and nonadditive manner. Furthermore, the effect of 10(-8) M DABK is completely reversed by calphostin C; (v) 10(-8) M DABK increases phosphoserine residue levels by 54%. This effect is completely reversed by 10(-7) M calphostin C.

[Video-assisted parathyroidectomy in the management of patients with primary hyperparathyroidism]. / Place actuelle de la chirurgie vidéo-assistée dans le traitement de l'hyperparathyroïdie primaire.

INTRODUCTION: In recent years, different minimally invasive techniques of parathyroidectomy have been described. We performed a retrospective study to evaluate the indications and results of video-assisted parathyroidectomy (Vap) in the management of our patients with primary hyperparathyroidism (PHPT). MATERIALS AND METHODS: During the last 5 years (1998-2002), we operated on 528 patients with PHPT. Vap was proposed for patients with sporadic PHPT, without associated goiter and without previous neck surgery, in whom a single adenoma was localized by means of sonography and/or sestamibi scanning. Vap was performed by lateral approach with insufflation for patients with adenoma located deeply in the neck and by gasless midline approach for patients with adenoma located anteriorly. A quick parathyroid (qPTH) assay was used during the surgical procedures. Calcemia, phosphoremia and PTH were systematically evaluated in patients on days 1 and 8, 1 month and 1 year after surgery. All patients underwent pre-operative and postoperative investigations of vocal cord movements. RESULTS: Among 528 patients with PHPT, 228 (43%) were not eligible for Vap: associated nodular goiter (99 cases), previous neck surgery (42 cases), suspicion of multiglandular disease (25 cases), lack of pre-operative localization (48 cases), and miscellaneous causes (14 cases). Vap was performed in 300 patients with sporadic PHPT: 282 lateral access, 17 midline access and 1 thoracoscopy. Median operative time was 50 min (20-130 min). Conversion to conventional parathyroidectomy was required in 42 patients (14%): missed adenomas (11 cases), difficulties of dissection (7 cases), multiglandular disease correctly predicted by qPTH (10 cases); qPTH assay false negative results (3 cases), sestamibi scan false positive results (10 cases) and 1 sonography false positive result. One patient presented definitive recurrent nerve palsy. One patient had a persistent PHPT and one other patient had a recurrent PHPT. CONCLUSION: Vap can be proposed for more than half of patients with PHPT. In our experience Vap and conventional parathyroidectomy are complementary. Immediate results of Vap are similar to those obtained with conventional parathyroidectomy but no conclusions can be drawn in terms of influence of Vap on the outcome of the patients operated for PHPT.

Thyroid and pituitary thyroxine-5'-deiodinase activity and thyrotrophin secretion in lithium-treated rats.

Some authors have reported increased serum thyrotrophin (TSH) in animals chronically treated with lithium, suggesting that lithium might decrease pituitary thyroxine (T(4))-5'-deiodinase activity. On the other hand, the effect of lithium treatment on thyroidal T(4)-5'-deiodinase activity is also unknown. The present study was undertaken to evaluate the effects of lithium treatment on pituitary and thyroid T(4)-5'-deiodinase activity. Serum and pituitary TSH levels and thyroidal and pituitary T(4)-5'-deiodinase activities were determined in 3-month-old isogenic male Dutch-Miranda rats treated with lithium for 8 weeks. Chronic lithium treatment produced a slight increase in pituitary TSH content, but no change in serum TSH, and a significant increase in the thyroidal T(4)-5'-deiodinase activity. However, the pituitary T(4)-5'-deiodinase activity was unaffected by lithium administration. As far as we know, the present data show for the first time that chronic lithium treatment can increase the thyroxine to tri-iodothyronine conversion in the murine thyroid gland, be it directly or indirectly.

Thyroid function and aging: gender-related differences.

The effects of aging on human or animal thyroid function are still not well defined. We evaluated some aspects of thyroid function during aging using an animal model (young and old Dutch-Miranda rats). In old rats of both genders, serum thyroxine (T4) decreased but serum thyrotrophin (TSH) remained unaltered, suggesting a disturbance in the pituitary-thyroid feedback mechanism during aging. Serum tri-iodothyronine (T3) only decreased in old males, possibly because female rats are almost twice as efficient in hepatic T4 to T3 deiodination. Thyroidal T4-5'-deiodinase activity did not change much during aging, although it decreased slightly in males. Thyroidal iodothyronine-deiodinase type I mRNA expression but not total thyroidal enzymatic activity were higher in female than in male rats. Thus, ovarian/testicular hormones may modulate the expression and/or the activity of hepatic and thyroidal type I iodothyronine-deiodinase. Thyroperoxidase (TPO) and thyroglobulin (Tg) expression were higher in young male rats than in females. In males, TPO and Tg gene expression decreased with aging, suggesting that androgens might increase their expression. Our results showed that aging induces real changes in rat thyroid gland function and regulation, affecting at least pituitary, thyroid and liver functions. Furthermore, some of these changes were gender related, indicating that gonadal hormones may modulate thyroid gland function and regulation.

Short- and long-term influences of calcitonin gene-related peptide on the synthesis of acetylcholinesterase in mammalian myotubes.

The present study analyses the short- (15 min - 2 h) and long-term (24 - 48 h) influences of calcitonin gene-related peptide (CGRP) on acetylcholinesterase (AChE) expression in the rat cultured skeletal muscle and the signal transduction events underlying CGRP actions. To assess the effect of CGRP on AChE synthesis, myotubes were pre-exposed to the irreversible AChE inhibitor diisopropyl fluorophosphate (DFP) and treated with CGRP or forskolin, an adenylyl cyclase (AC) activator. Treatment of myotubes with 1 - 100 nM CGRP for 2 h increased by up to 42% the synthesis of catalytically active AChE with a parallel increase in the intracellular cyclic AMP. The stimulation of AChE synthesis induced by CGRP was mimicked by direct activation of AC with 3 - 30 microM forskolin. In contrast, pre-treatment of cultures with 100 nM CGRP for 20 h reduced by 37% the subsequent synthesis of AChE, resulting in a 15% decrease in total AChE activity after 48 h CGRP treatment. Moreover, 24 h treatment of myotubes with 100 nM CGRP reduced by 54% the accumulation of cyclic AMP induced by a subsequent CGRP treatment. These findings indicate that, in skeletal muscle cells, CGRP modulates the AChE expression in a time-dependent manner, initially stimulating the enzyme synthesis through a cyclic AMP-dependent mechanism. The decreased AChE synthesis observed after long-term CGRP treatment suggests that CGRP signalling system is subject to desensitization or down-regulation, that might function as an important adaptative mechanism of the muscle fibre in response to long-term changes in neuromuscular transmission.

The effect of nitrous oxide on the inhibition of somatosensory evoked potentials by sevoflurane in children.

Inhalational anaesthetics inhibit somatosensory evoked potentials. The present study examined the effect of nitrous oxide in anaesthetic mixture with sevoflurane on the somatosensory evoked potential in children. Forty-five patients aged between 6 months and 6 years undergoing club foot surgery were studied to verify the influence of sevoflurane alone (21 patients) and sevoflurane with nitrous oxide (24 patients) on the somatosensory evoked potential. Fractional inspired concentration of nitrous oxide and fractional end-tidal (alveolar) sevoflurane were measured to estimate the multiples and submultiples of the minimal alveolar concentration (age corrected). The somatosensory evoked potential signals were obtained by stimulation of the median nerve. Nitrous oxide (FI = 0.63 +/- 2.5) with sevoflurane caused more reduction in the amplitude of somatosensory evoked potential waves and a greater increase in the latency of somatosensory evoked potential waves in comparison with sevoflurane alone. The results show that it is possible to obtain the inhibition of somatosensory evoked potential with smaller concentrations of sevoflurane, when it is used with nitrous oxide.

Tunneling phenomena as a probe to investigate atomic scale fluctuations in Metal/Oxide/Metal magnetic tunnel junctions

Local transport properties of Al2O3 tunnel barriers have been investigated at a nanometric spatial scale with an unconventional near field microscope. Using the tunneling effect, which is extremely sensitive to fluctuations of the barrier parameters (less than 1 to 2 A), a unique method is introduced to investigate the tunnel barrier quality. This technique provides atomic scale information on the barrier characteristics which cannot be obtained by conventional surface analysis techniques since they are all subject to averaging over surface and depth.