Interaction of methyl-jasmonate and Fusarium poae in bread wheat.

Fusarium Head Blight (FHB) is a devastating disease that affects the grain yield and quality of essential crops such as wheat. In the last years, some Fusarium species have acquired particular importance as Fusarium poae. However, studies to evaluate F. poae-wheat interaction are still scarce. The interaction between F. poae and two bread wheat cultivars with different resistance levels against FHB was evaluated. Moreover, the application of methyl-jasmonate (MeJA) was evaluated as a possible tool to reduce the fungal presence. Our results showed that the MeJA treatment is isolate-dependent, reducing F. poae fungal growth. A decrease in fungal biomass was observed in the susceptible cultivar after MeJA application; however, no differences between inoculated and inoculated-MeJA treatments were observed in the resistant cultivar. Finally, the F. poae inoculation induces the expression of PR1-1 and PDF 1.2, being early in the resistant cultivar compared to the susceptible ones. The application of MeJA combined with the F. poae inoculation increased PR1-1 and PDF1.2 expressions in resistant cultivars. To our knowledge, this is the first study that evaluates the interaction between F. poae and wheat and the MeJA treatment as a possible management strategy against this important pathogen.

Evaluation of the effects of chronic occupational exposure to metallic mercury on the thyroid parenchyma and hormonal function.

INTRODUCTION: Experiments in animals exposed to mercury (Hg) in different chemical states have shown thyroid parenchymal and hormone alterations. However, these experiments did not allow the establishment of dose-response curves or provide an understanding of whether these Hg effects on the thyroid parenchyma occur in humans. OBJECTIVE: To evaluate the association between chronic occupational exposure to metallic Hg and alterations in thyroid hormones and gland parenchyma 14 years after the last exposure. METHODS: A cross-sectional study including 55 males exposed in the past to metallic Hg and 55 non-exposed males, paired by age, was conducted in the Hospital das Clínicas (Brazil) from 2016 to 2017. Serum concentrations of total and free triiodothyronine (TT3 and FT3), free thyroxine (FT4), thyrotropin (TSH), reverse T3 (RT3), selenium and antithyroid antibody titers were obtained. The Hg and iodine concentrations were measured in urine. The thyroid parenchyma was evaluated by B-mode ultrasonography with Doppler. The nodules with aspects suspicious for malignancy were submitted to aspiration puncture with a thin needle, and the cytology assessment was classified by the Bethesda system. The t test or Mann-Whitney test, Chi-square test and Spearman correlation were used to compare the exposed and non-exposed groups and examine the relationships between the variables. Univariate and multivariate logistic regression models were used to trace determinants of the risk of thyroid hormone alteration. Statistical significance was defined by p < 0.05. RESULTS: The urinary Hg average was significantly higher in the exposed group than in the non-exposed group (p < 0.01). The mean TSH serum concentration in the exposed group was higher, with a statistically significant difference between the groups (p = 0.03). Serum concentrations of TSH exceeded the normality limit (4.20 µIU/ml) in 13 exposed individuals (27.3%) and 4 non-exposed individuals (7.3%), with a statistically significant association between the hormonal increase and exposure to Hg (p = 0.02). In the logistic regression model, exposure to Hg (yes or no) showed an odds ratio = 4.86 associated with an increase of TSH above the normal limit (p = 0.04). The serum concentrations of RT3 showed a statistically borderline difference between the groups (p = 0.06). There was no statistically significant difference between the mean TT3, FT3 and FT4 serum concentrations in the Hg-exposed group compared to the non-exposed group. The proportions of the echogenicity alterations were higher in the exposed group compared to the non-exposed group (27.3% versus 9.1%; p = 0.03). Papillary carcinomas were documented in three exposed individuals and one non-exposed individual. A follicular carcinoma was recorded in one non-exposed individual. CONCLUSIONS: Due to the higher serum TSH concentration and the prevalence of parenchymal alterations in the Hg-exposed group, even after cessation of exposure, it is recommended that the thyroid status of exposed workers be followed for a long period.

Quantitative phase analysis from X-ray diffraction in Y-TZP dental ceramics: a critical evaluation.

UNLABELLED: The dentistry literature shows consensus to use the Garvie and Nicholson equation modified by Toraya to quantify the Y-TZP phase transformation. However, this method does not include the possibility of cubic phase transformation and crystallographic texture after artificial ageing, and in this case, it is possible to observe errors of quantification. OBJECTIVES: The aim of this study was to evaluate a dental Y-TZP ageing kinetic of phase transformation under pressure and hydrothermal conditions (130°C, 2bar) and to compare the methods of quantification by the equation of Garvie and Nicholson modified by Toraya and the Rietveld refinement method. METHODS: Discs of Y-TZP (12mm Ø×1.2mm in height) were divided into groups (n=4) according to the ageing times (in the range of 6 and 138h). The superficial characterisation was made using SEM and the XDR for crystallographic analysis. RESULTS: An aggressive superficial degradation process at the beginning of phase transformation in 6-10h of ageing was observed by SEM. The phase transformation quantification showed differences between the methods. It was observed the increase and stabilisation of monoclinic phase until 80% at 40h of ageing by the Garvie and Nicholson modified by Toraya equation, compared to 60% of monoclinic phase and approximately 30% of cubic phase observed by the Rietveld method. CONCLUSION: The Toraya equation showed an overestimated result of monoclinic quantification compared to the Rietveld method. CLINICAL SIGNIFICANCE: The overestimated result of monoclinic phase could lead to different interpretation about the dental Y-TZP ageing process.

An exploratory survey of eating behaviour patterns in adolescent students.

OBJECTIVE: Empirical research has always treated adolescents' eating habits from a variable-centered perspective, but this approach may miss the configurations of eating behaviours that uniquely describe discrete groups of individuals. The aim of this study was to investigate prototypical patterns of eating habits in a large sample of Italian adolescents and their behavioural and psychological correlates. METHOD: Data were gathered from 1388 students (F=60%, mean age 14.90±1.34 yrs), who were asked to fill in an original questionnaire surveying dietary habits, body weight attitudes, body image, sport activities and sources of information about food. Perfectionism, self-esteem, self-efficacy and care for food were also assessed as well-known psychological risk factors for Eating Disorders. RESULTS: Five prototypical eating behaviour patterns were identified through cluster analysis. Cluster membership was associated (p<0.05) with gender, age and age- and gender-correct BMI percentile, perceived relevance of physical appearance in achieving success in life; one's weight and body image evaluation, dieting, physical activity, self-efficacy, self-esteem and care for food. Clusters did not differ in perfectionism score and in frequency of consulting different sources of information about food and weight, except in the case of dieticians. CONCLUSION: The identification of prototypical eating habits patterns revealed a large range of wrong eating attitudes and behaviours among Italian adolescents. Such data suggest the need to develop and implement adequate prevention programs.

Respiratory activity in brainstem of fetal mice lacking glutamate decarboxylase 65/67 and vesicular GABA transporter.

The respiratory neural network in the mammalian medulla oblongata shows rhythmic activity before birth. GABA and glycine are considered to be involved in control of respiratory rhythm. Recently we have demonstrated respiratory failure in glutamic acid decarboxylase (GAD) 67-deficient mice [Tsunekawa N, Arata A, Obata K (2005) Development of spontaneous mouth/tongue movement and related neural activity, and their repression in mouse fetus lacking glutamate decarboxylase 67. Eur J Neurosci 21:173-178]. To further evaluate the involvement of GABA and glycine in fetal respiratory function, we studied neural activities in brainstem-spinal cord blocks prepared from GAD65-/-:67-/- and vesicular GABA transporter (VGAT)-/-mice on embryonic day 14 (E14)-E15 and E18. In these knockout mice, the synthesis of GABA and the vesicular release of GABA and glycine are completely absent, respectively. Spontaneous respiratory discharges were observed in the ventral roots at the cervical cord (C) 4 level from wild-type mice but not from the knockout mice on E18. Administration of substance P induced C4 discharges in GAD65-/-:67-/- preparations but not in VGAT-/- preparations. C4 discharges were observed in the knockout mice on E14-E15, although the frequency was lower than that in the wild-type. Neuronal activities in the respiratory network of the E18 brainstem were recorded using a "blind" patch-clamp technique. Expiratory and inspiratory neurons with their characteristic firing patterns were observed in the wild-type fetuses. Strychnine reversed inspiratory-phase hyperpolarization to large depolarization in expiratory neurons. On the other hand, neurons in the same area of the knockout mice fired spontaneously without any rhythm. Substance P induced hyperpolarizing potentials in medullary neurons of GAD65-/-:67-/- mice. Further administration of strychnine induced large depolarizing potentials. Rhythmic activities were not observed in VGAT-/- mice even in the presence of substance P and strychnine. These results indicate that the lack of GABA and glycine impairs the function of the respiratory network in mouse fetuses and the impairment progresses with fetal age.

Multiplex polymerase chain reaction for distinguishing Taylorella equigenitalis from Taylorella equigenitalis-like organisms.

It is difficult to distinguish isolates of Taylorella equigenitalis, the cause of contagious equine metritis, from a T. equigenitalis-like organism isolated from asymptomatic donkeys and horses. Although T. equigenitalis is responsible for a severe, contagious disease of the reproductive tract of equids, the T. equigenitalis-like organism, although contagious, does not appear to produce disease. Because of the economic consequences of correctly distinguishing isolates of these 2 microorganisms, a polymerase chain reaction (PCR)-based assay was developed that will distinguish isolates of T. equigenitalis from the T. equigenitalis-like microorganism. The primers used in the PCR assay were designed to amplify unique regions of the gene encoding the 16S ribosomal RNA.

Taylorella asinigenitalis sp. nov., a bacterium isolated from the genital tract of male donkeys (Equus asinus).

Three bacterial isolates that were phenotypically indistinguishable from Taylorella equigenitalis were obtained from the urethral fossae of three male donkeys (Equus asinus), one located in the state of California and the other two in the state of Kentucky, USA. Based on results of pulsed-field gel electrophoresis, the isolate from California differed from the two Kentucky isolates, which were the same. Mares bred artificially (California) or naturally (Kentucky) did not show signs of disease, even though infection with the organism was established in those bred naturally. Mares and, uncharacteristically, all three jacks produced antibodies that reacted in the complement fixation test utilized to identify mares recently infected with T. equigenitalis. Sequence analysis of DNA encoding the 16S rRNA revealed that the gene sequences of these isolates were virtually identical to each other (>99.8% similarity), but different (97.6% similarity) from those of several confirmed isolates of T. equigenitalis. The 16S rDNA sequences of the latter were 100% identical. DNA-DNA hybridization studies revealed a mean hybridization level of 89% between the donkey isolate from California and the donkey isolate from Kentucky. On the other hand, the mean DNA-DNA hybridization level from the donkey isolates with DNA from a strain of T. equigenitalis was 23%. The DNA G+C composition was 37.8 mol% for the two donkey isolates, as well as the strain of T. equigenitalis used in the hybridization studies. These data support our opinion that micro-organisms isolated from the male donkeys are different from T. equigenitalis and it is proposed that they be considered a new species within the genus Taylorella and named Taylorella asinigenitalis sp. nov. The type strain is strain UCD-1T (= ATCC 700933T = LMG 19572T).

Effects of substitution of conserved amino acid residues on the sugar-binding property of the tandem-repeat 32-kDa galectin of the nematode Caenorhabditis elegans.

The 32-kDa galectin (LEC-1) of the nematode Caenorhabditis elegans (C elegans) is composed of two tandemly repeated homologous sequences, each containing a carbohydrate-recognition domain (CRD). Using the polymerase chain reaction (PCR) with LEC-1 cDNA as a template and "megaprimers", we performed site-directed mutagenesis to substitute conserved amino acid residues in these domains. The resultant mutated LEC-1s were produced in E. coli, and their binding abilities were estimated by affinity chromatography. When one of the conserved amino acid residues in the first lectin domain was substituted, the binding ability of the mutant protein to asialofetuin-agarose was reduced but still remained. The binding ability of such mutants was similar to that of the recombinant half molecule containing the second lectin domain (Ch). However, when mutations were introduced into the second lectin domain, the binding ability of these mutant lectins to asialofetuin-agarose was significantly reduced just like the half recombinant molecule containing the first lectin domain (Nh). The different effects of the substitution of amino acid residues on the two lectin domains suggest that the binding properties of the two sites are different and that LEC-1 acts as a "heterobifunctional crosslinker."

Transient configurations of baroresponsive respiratory-related brainstem neuronal assemblies in the cat.

The regulation of gas exchange requires coordination of the respiratory and cardiovascular systems. Previous work suggested that medullary raphe neurones transform and transmit information from baroreceptors to neurones in the ventral respiratory group. This study tested the hypothesis that distributed brainstem neuronal assemblies are transiently reconfigured during the respiratory cycle and baroreceptor stimulation. Blood pressure was perturbed by intravenous injection of an alpha1-adrenergic receptor agonist, unilateral pressure changes in the carotid sinus, or occlusion of the descending aorta in 14 Dial-urethane anaesthetized, vagotomized, paralysed, artificially ventilated cats. Neurones were monitored simultaneously with microelectrode arrays in two or more of the following sites: n. raphe obscurus, n. raphe magnus, rostral and caudal ventrolateral medulla, and the nucleus tractus solitarii. Transient configurations of baroresponsive assemblies were detected with joint pericycle-triggered histograms, the gravitational representation, and related pattern detection methods. Data were also analysed with cycle-triggered histograms, peristimulus-time and cumulative sum histograms, cross-correlograms, spike-triggered averages of efferent phrenic activity, and joint impulse configuration scatter diagrams (snowflakes). Five to nine simultaneously recorded spike trains from control expiratory phases were compared with data from interleaved equal-duration time blocks from control inspiratory phases. In each of seven animals, significant impulse synchrony detected by gravity analysis was confined to one phase of the respiratory cycle. Repeated patterns of distributed synchrony confined to periods of altered baroreceptor activity were detected and involved neurones that individually did not change firing rates during stimulation. Snowflakes and logical cross-correlation analysis provided evidence for the cooperative actions of impulses in concurrently active parallel channels. In 12 of 17 pairs of neurones with at least one baroresponsive cell, joint pericycle-triggered histograms detected synchrony indicative of shared inputs or functional excitatory interactions that varied as a function of time in the respiratory cycle. Neurones in four of the pairs had no respiratory modulation of their individual firing rates. Data from eight other pairs were indicative of fluctuations in inhibition during the respiratory cycle. The results demonstrate repeated transient configurations of baroresponsive neuronal assemblies during the respiratory cycle, without concomitant firing rate changes in the constituent neurones, and suggest distributed network mechanisms for the modulation of baroreceptor-mediated reflexes.

Rnx deficiency results in congenital central hypoventilation.

The genes Tlx1 (Hox11), Enx (Hox11L2, Tlx-2) and Rnx (Hox11L2, Tlx-3) constitute a family of orphan homeobox genes. In situ hybridization has revealed considerable overlap in their expression within the nervous system, but Rnx is singularly expressed in the developing dorsal and ventral region of the medulla oblongata. Tlx1-deficient and Enx-deficient mice display phenotypes in tissues where the mutated gene is singularly expressed, resulting in asplenogenesis and hyperganglionic megacolon, respectively. To determine the developmental role of Rnx, we disrupted the locus in mouse embryonic stem (ES) cells. Rnx deficient mice developed to term, but all died within 24 hours after birth from a central respiratory failure. The electromyographic activity of intercostal muscles coupled with the C4 ventral root activity assessed in a medulla-spinal cord preparation revealed a high respiratory rate with short inspiratory duration and frequent apnea. Furthermore, a coordinate pattern existed between the abnormal activity of inspiratory neurons in the ventrolateral medulla and C4 motorneuron output, indicating a central respiratory defect in Rnx mice. Thus, Rnx is critical for the development of the ventral medullary respiratory centre and its deficiency results in a syndrome resembling congenital central hypoventilation.

[Perforation of primary non-Hodgkin's lymphoma during chemotherapy. Clinical evaluation and therapeutic strategy]. / Perforazione di linfoma non-Hodgkin del cieco dopo chemioterapia. Valutazione clinica e strategia terapeutica.

Primary cecal lymphoma are very rare. The case is reported of an elderly woman having voluntary preliminary chemotherapy with consequent cecum perforation due to tumoral necrosis, some days after the first chemotherapy. The diagnostic, clinical and therapeutic protocol is analysed and stress is laid on the rare clinical cases described. Resection is advisable in the still delimited forms in order to avoid surgical complications due to preliminary chemotherapy and in order to classify precisely the neoplasm.

Medullary raphe neurones and baroreceptor modulation of the respiratory motor pattern in the cat.

1. Perturbations of arterial blood pressure change medullary raphe neurone activity and the respiratory motor pattern. This study sought evidence for actions of baroresponsive raphe neurones on the medullary respiratory network. 2. Blood pressure was perturbed by intravenous injection of an alpha1-adrenergic receptor agonist, unilateral pressure changes in the carotid sinus, or occlusion of the descending aorta in thirty-six Dial-urethane-anaesthetized, vagotomized, paralysed, artificially ventilated cats. Neurones were monitored with microelectrode arrays in two or three of the following domains: nucleus raphe obscurus-nucleus raphe pallidus, nucleus raphe magnus, and rostral and caudal ventrolateral medulla. Data were analysed with cycle-triggered histograms, peristimulus time and cumulative sum histograms, cross-correlograms and spike-triggered averages of efferent phrenic nerve activity. 3. Prolongation of the expiratory phase and decreased peak integrated phrenic amplitude were most frequently observed. Of 707 neurones studied, 310 had altered firing rates during stimulation; changes in opposite directions were monitored simultaneously in fifty-six of eighty-seven data sets with at least two baroresponsive neurones. 4. Short time scale correlations were detected between neurones in 347 of 3388 pairs. Seventeen pairs of baroresponsive raphe neurones exhibited significant offset correlogram features indicative of paucisynaptic interactions. In correlated raphe-ventrolateral medullary neurone pairs with at least one baroresponsive neurone, six of seven ventrolateral medullary decrementing expiratory (E-Decr) neurones increased their firing rate during baroreceptor stimulation. Thirteen of fifteen ventrolateral medullary inspiratory neurones correlated with raphe cells decreased their firing rate during baroreceptor stimulation. 5. The results support the hypothesis that raphe neuronal assemblies transform and transmit information from baroreceptors to neurones in the ventral respiratory group. The inferred actions both limit and promote responses to sensory perturbations and match predictions from simulations of the respiratory network.

Activity of rat pump neurons is modulated with central respiratory rhythm.

The firing properties of the second-order neurons of the slowly-adapting pulmonary stretch receptors called pump neurons (P-cells), were studied in Nembutal-anesthetized, paralyzed, and artificially-ventilated rats. Extracellular recording was made from single P-cells which were monosynaptically activated by electrical stimulation of the vagal afferents and fired in phase with lung inflations. In the majority of the P-cells examined (49/52), the firing was suppressed to various extents in the inspiratory phase: in effect, their firing was accentuated at the time of the inspiratory off-switch. This issue has never been reported in cat P-cells, on which relatively rich data have been accumulated. The present results suggest that rat P-cells do not only relay information from the lung stretch receptors but also integrate the central respiratory inputs.

The adrenergic modulation of firings of respiratory rhythm-generating neurons in medulla-spinal cord preparation from newborn rat.

We analysed the modulation of respiratory neurons by adrenaline or noradrenaline (NA) in a newborn rat brainstem-spinal cord preparation. Adrenaline or NA caused a dose-dependent depression of the respiratory rhythm and induced C4 spinal tonic discharges. The inhibitory effect of adrenaline (ED50=0.5 microM) on the respiratory rhythm was stronger than NA (ED50=5 microM). The adrenaline respiratory rhythm depression was partially blocked by the alpha1-antagonist prazosin or by the alpha2-antagonist yohimbine. The C4 tonic discharge elicited by adrenaline was blocked by the alpha1-antagonist prazosin. The direct effects of adrenaline on pre-inspiratory (Pre-I) neurons were examined in a synaptic blockade solution (low Ca), and fifty-six percent of Pre-I neurons were found to continue firing. In low-Ca solution, Pre-I neurons were excited (n=29 of 39) or depressed (n=5 of 39) by adrenaline, and excited by alpha1-agonist phenylephrine or depressed by alpha2-agonist clonidine. These results suggest that the respiratory rhythm depression under intact network conditions is mediated by some other inhibitory system. The inhibitory effect of adrenaline on the respiratory rhythm was partially blocked by the GABA(A)-antagonists bicuculline or picrotoxin, but not by the GABA(B)-antagonist phaclofen. The present results suggest that: (1) respiratory rhythm generation is more sensitive to adrenaline than NA through alpha-adrenergic action of adrenaline; (2) the activity of Pre-I neurons could be directly regulated by excitation via alpha1-receptors and inhibition via alpha2-receptors; and (3) the depression of the respiratory rhythm by adrenaline is partly mediated by GABA(A)ergic neurons.

Possible synaptic connections of expiratory neurons in the medulla of newborn rat in vitro.

To elucidate synaptic interactions between expiratory (Exp) and other respiratory neurons in the ventrolateral medulla of brain stem-spinal cord preparations from newborn rats, we analyzed postsynaptic potentials in Exp and a subclass of inspiratory (Insp) neurons using whole-cell recordings. About 72% of the Exp neurons (Exp-p-i) showed Cl--dependent synaptic inhibition during the Insp and pre/post-Insp phases, corresponding to the active phase of the Insp and pre-inspiratory (Pre-I) neurons, respectively. The other 28% neurons (Exp-i) received Cl--dependent inhibition during the Insp phase only. Some Insp neurons showed reversed IPSPs during the active phase of Exp-p-i after Cl-loading. We suggest the existence of inhibitory connections from Pre-I and Insp to Exp and from Exp to Insp neurons. Basic synaptic connections among respiratory neurons similar to those in intact adult mammals may already exist in newborn rats.

Validación del sistema APACHE II en cuatro Unidades Intensivas del área de Buenos Aires / Validation of APACHE II system in four intensive care units of the Buenos Aires area

Objetivos: Analizar la calibración y discriminación del Sistema APACHE II en cuatro UTIs Polivalentes de Hospitales de Alta Complejidad. Material y Métodos: Se recabó prospectivamente la información necesaria para el cálculo del score APACHE II a las 24 horas del ingreso, durante el período comprendido entre enero de 1994 a enero 1997, en cuatro UTI polivalentes de Centros de Alta Complejidad de Buenos Aires. Los criterios de exclusión fueron: edad menor de 16, cirugía cardiovascular y quemados. Se recabaron diariamente la edad, causa de ingreso a UTI según categorías de Knaus, ingreso por cirugía de urgencia o electiva, sumatoria de puntos de APACHE II y evolución. La evolución fue considerada como sobrevida (SV) o muerte (NS) durante la estancia hospitalaria. El cálculo de PM se efectuó utilizando los coeficientes de la ecuación original: PM =e Logit/ 1 + e Logit. Se analizaron los datos por medio de regresión logística múltiple. La calibración se efectuó por medio del estadístico Goodness of Fit de Hosmer y Lemeshow. La discriminación se analizó por medio de curvas ROC. Resultados: Se recolectó un total de 3137 registros para el análisis. La edad media fue 57 ñ 19 años, el APACHE II de 12,8 ñ 7,8 y la estdía en UTI de 7,6 ñ 6,4 días. La mortalidad renal fue de 33 por ciento. Existieron diferencias significativas entre APACHE II de SV 9,9 ñ 5,9 y de NS 18,6 ñ 8 (p<0.001). La mortalidad calculada fue de 20 ñ 18 por ciento. Se observó una correlación positiva entre outcome calculado y real (R² 0,74). Sin embargo el outcome calculado por APACHE II presentó una mala calibración con el real (Goodness of Fit 39,87 - p < 0,001). La discriminación arrojó un área bajo ROC de 0,78. Para un punto de corte de PM de 0,5 la Sensibilidad fue del 29,4 por ciento y la Especificidad del 97,5 por ciento. El valor predictivo positivo fue de 45,5 por ciento y el negativo de 91,6 por ciento. Conclusiones: el sistema APACHE II no valida correctamente los datos de mortalidad en la muestra estudiada. La mortalidad global real es mayor que la calculada según la ecuación PM. Esto hace caer en forma significativa el valor predictivo positivo y la sensibilidad del modelo comparados con la publicación original. Según las conclusiones del presente estudio, se propone la realización de un trabajo multicéntrico nacional para la validación del sistema en la población de pacientes de terapia intensiva y la confección de nuevos coeficientes que se ajusten...

Validación del sistema APACHE II en cuatro Unidades Intensivas del área de Buenos Aires / Validation of APACHE II system in four intensive care units of the Buenos Aires area

Objetivos: Analizar la calibración y discriminación del Sistema APACHE II en cuatro UTIs Polivalentes de Hospitales de Alta Complejidad. Material y Métodos: Se recabó prospectivamente la información necesaria para el cálculo del score APACHE II a las 24 horas del ingreso, durante el período comprendido entre enero de 1994 a enero 1997, en cuatro UTI polivalentes de Centros de Alta Complejidad de Buenos Aires. Los criterios de exclusión fueron: edad menor de 16, cirugía cardiovascular y quemados. Se recabaron diariamente la edad, causa de ingreso a UTI según categorías de Knaus, ingreso por cirugía de urgencia o electiva, sumatoria de puntos de APACHE II y evolución. La evolución fue considerada como sobrevida (SV) o muerte (NS) durante la estancia hospitalaria. El cálculo de PM se efectuó utilizando los coeficientes de la ecuación original: PM =e Logit/ 1 + e Logit. Se analizaron los datos por medio de regresión logística múltiple. La calibración se efectuó por medio del estadístico Goodness of Fit de Hosmer y Lemeshow. La discriminación se analizó por medio de curvas ROC. Resultados: Se recolectó un total de 3137 registros para el análisis. La edad media fue 57 ñ 19 años, el APACHE II de 12,8 ñ 7,8 y la estdía en UTI de 7,6 ñ 6,4 días. La mortalidad renal fue de 33 por ciento. Existieron diferencias significativas entre APACHE II de SV 9,9 ñ 5,9 y de NS 18,6 ñ 8 (p<0.001). La mortalidad calculada fue de 20 ñ 18 por ciento. Se observó una correlación positiva entre outcome calculado y real (R² 0,74). Sin embargo el outcome calculado por APACHE II presentó una mala calibración con el real (Goodness of Fit 39,87 - p < 0,001). La discriminación arrojó un área bajo ROC de 0,78. Para un punto de corte de PM de 0,5 la Sensibilidad fue del 29,4 por ciento y la Especificidad del 97,5 por ciento. El valor predictivo positivo fue de 45,5 por ciento y el negativo de 91,6 por ciento. Conclusiones: el sistema APACHE II no valida correctamente los datos de mortalidad en la muestra estudiada. La mortalidad global real es mayor que la calculada según la ecuación PM. Esto hace caer en forma significativa el valor predictivo positivo y la sensibilidad del modelo comparados con la publicación original. Según las conclusiones del presente estudio, se propone la realización de un trabajo multicéntrico nacional para la validación del sistema en la población de pacientes de terapia intensiva y la confección de nuevos coeficientes que se ajusten...(AU)

Neuronal mechanisms of respiratory rhythm generation: an approach using in vitro preparation.

The respiratory network in the ventrolateral medulla of the brainstem-spinal cord preparation from newborn rat involves pre-inspiratory (Pre-I) neurons, three types of inspiratory (Insp I, II, III) neurons and two types of expiratory (Exp-i, Exp-p-i) neurons as major subtypes, which were classified according to patterns of postsynaptic potentials. The neuronal respiratory-related membrane potential fluctuations of these cells indicate at least four distinguishable phases of the in vitro respiratory cycle: pre-inspiratory, inspiratory, post-inspiratory (E1), and late-expiratory (E2). A current hypothesis for the central pattern generator of respiration proposed by our group is that Pre-I neurons in the rostral ventrolateral medulla, with intrinsic burster properties, produce the primary respiration rhythm. This rhythm triggers an inspiratory pattern generator composed of Insp neurons in the rostral and caudal ventrolateral medulla. Respiratory neurons possess several types of ionic channels which are involved in the generation of rhythm and burst pattern. Particularly, P-type Ca2+ channels and TTX-sensitive persistent Na+ channels are postulated to contribute to the intrinsic burst generation of Pre-I neurons. N-type Ca2+ channels may be involved in the maintenance and termination of inspiratory burst activity via the activation of Ca2(+)-dependent K+ channels. Respiratory neuron networks in this preparation were compared with those of different in vitro preparations, like rhythmic slices or perfused brainstems and of adult mammals in vivo. Many types of synaptic connections among respiratory neurons in adult mammals were also found in the (rostral) ventrolateral medulla of a brainstem-spinal cord preparation from newborn rat. The characteristics of the inspiratory burst pattern and inspiratory off switch mechanisms in newborn rat preparations might be explained by insufficient inhibitory (or excitatory) synaptic inputs to the inspiratory pattern generator due to an immature neuron network and/or deafferentiation.