Spatial and temporal variation of the vegetation of the semiarid Puna in a pastoral system in the Pozuelos Biosphere Reserve.

This study aimed to analyze the spatial and temporal variation of the vegetation in the northern Argentine Puna, utilizing both field sampling and remote-sensing tools. The study was performed within the Pozuelos Biosphere Reserve (Jujuy province, Argentina), which aims to generate socio-economic development compatible with biodiversity conservation. Our study was designed to analyze the dynamics of the Puna vegetation at local scale and assess and monitor the seasonal (dry and wet seasons), interannual, and spatial variation of the vegetation cover, biomass, dominant species, and vegetation indices. Ten vegetation units (with differences in composition, cover, and high and low stratum biomass) were identified at our study site. The diversity of these vegetation units correlated with geomorphology and soil type. In the dry season, the vegetation unit with greatest vegetation cover and biomass was the Festuca chrysophylla grassland, whereas in the wet season, the units with greatest cover and biomass were vegas (peatlands) and short grasslands. The Festuca chrysophylla grasslands and short grasslands were located in areas with clay soils, except peatlands, associated with valleys and coarse-texture soils. The vegetation indices used (NDVI, SAVI, and MSAVI2) were able to differentiate functional types of vegetation and showed a good statistical fit with cover values. Our results suggest that the integrated utilization of remote-sensing tools and field surveys improves the assessment of the Puna vegetation and would allow a periodic monitoring at production unit scale taking into account its spatial and temporal variation.

Locating the cricothyroid membrane in males: Influence of the morphological characteristics of the neck. / Localización de la membrana cricotiroidea en varones: influencia de las características morfológicas del cuello.

INTRODUCTION: Cricothyrotomy is a recommended technique to restore oxygenation in most of guidelines for difficult airway management. A correct location of the cricothyroid membrane (CTM) is fundamental for a proper performance of the technique. Several studies have shown poor accuracy with the identification the CTM by palpation, resulting in a high failure rate of the technique. OBJECTIVE: The aim of this study was to determine the impact of the patient's neck morphology on the accurate location of the CTM and on the time employed. MATERIALS AND METHOD: Observational study in which anaesthesiologists and intensivists voluntarily participated in a simulation that consisted of a «cannot intubate, cannot oxygenate¼ scenario, where they had to locate the CTM, as soon as possible, in 2 selected male patients with different morphological characteristics of the neck. The time was measured from the beginning of CTM palpation to locating it with a marker. RESULTS AND CONCLUSIONS: A higher body mass index and a higher neck circumference correlated with a 70% location failure rate and with a longer time as compared with a standard model.

Use of GlideScope for double lumen endotracheal tube insertion in an awake patient with difficult airway.

There is scientific evidence that an anticipated difficult airway must be managed with the patient being awake. The GlideScope has been proven to be a useful device to intubate the trachea in some instances when difficult airway is present, and particularly in the awake patient. It has also been used for double lumen tube (DLT) in the anaesthetized patient, but its use with DLT in both circumstances, awake patients with difficult airway has not been described. GlideScope enabled us to achieve accurate local anesthetic spraying and a successful endotracheal intubation with a double lumen tube (DLT) in an awake patient with predicted difficult airway and bronchoaspiration risk. Different ways to resolve cases like this can be found in the anesthetic literature, but we think this could be another option to bear in mind. We also describe a new variation in the maneuver of introducing a DLT into the trachea under GlideScope view as DLT presents with some difficulties when introduced under normal circumstances. This option could add some risk for the patients when used in inexperienced hands and there is not sufficient scientific evidence in the literature to recommend it for all cases.

Semantic dementia and persisting Wernicke's aphasia: linguistic and anatomical profiles.

Few studies have directly compared the clinical and anatomical characteristics of patients with progressive aphasia to those of patients with aphasia caused by stroke. In the current study we examined fluent forms of aphasia in these two groups, specifically semantic dementia (SD) and persisting Wernicke's aphasia (WA) due to stroke. We compared 10 patients with SD to 10 age- and education-matched patients with WA in three language domains: language comprehension (single words and sentences), spontaneous speech and visual semantics. Neuroanatomical involvement was analyzed using disease-specific image analysis techniques: voxel-based morphometry (VBM) for patients with SD and overlays of lesion digitized lesion reconstructions in patients with WA. Patients with SD and WA were both impaired on tasks that involved visual semantics, but patients with SD were less impaired in spontaneous speech and sentence comprehension. The anatomical findings showed that different regions were most affected in the two disorders: the left anterior temporal lobe in SD and the left posterior middle temporal gyrus in chronic WA. This study highlights that the two syndromes classically associated with language comprehension deficits in aphasia due to stroke and neurodegenerative disease are clinically distinct, most likely due to distinct distributions of damage in the temporal lobe.

Indolizidine 239Q and quinolizidine 275I. Major alkaloids in two Argentinian bufonid toads (Melanophryniscus).

Alkaloid profiles in skin of poison frogs/toads (Dendrobatidae, Mantellidae, Bufonidae, and Myobatrachidae) are highly dependent on diet and hence on the nature of habitat. Extracts of the two species of toads (Melanophryniscus klappenbachi and Melanophryniscus cupreuscapularis) from similar habitats in the Corrientes/Chaco Provinces of Argentina have similar profiles of alkaloids, which differ considerably in profiles from other Melanophryniscus species from Brazil, Uruguay and Argentina. Structures of two major alkaloids 239Q (1) and 275I (2) were determined by mass, FTIR, and NMR spectral analysis as 5Z,9Z-3-(1-hydroxybutyl)-5-propylindolizidine and 6Z,10E-4,6-di(pent-4-enyl) quinolizidine, respectively. A third alkaloid, 249F (3), is postulated to be a homopumiliotoxin with an unprecedented conjugated exocyclic diene moiety.

Seroprevalence of varicella among children and adolescents in Valencia, Spain. Reliability of the parent's reported history and the medical file for identification of potential candidates for vaccination.

This study assessed the seroprevalence of varicella antibodies in children and adolescents in Spain and evaluated the reliability of two methods for detecting susceptible individuals: (1) parental-reported history of varicella and (2) medically-documented histories maintained by the pediatrician. A total of 186 children (6 to 15 years of age) were recruited in 13 pediatric offices of Valencia, Spain. A brief case report form was completed including previous history of varicella referred by the parents, and a 5 mL blood sample was obtained. The pediatrician medical file was reviewed for antecedent of varicella. The overall prevalence of varicella antibodies was 84% and 88% in the 6-9 years and 10-15 years age brackets, respectively. The predictive value of a negative history of varicella disease was 48% by parental recall (52% "false negative"), and only 26% by medical record (74% "false negative"). However, the positive predictive value of a positive parental reported history or a positive medically-documented history was 95%. The most effective strategy for varicella vaccination of older children and adolescents in Spain will be to immunize those individuals with a lack of positive (unknown or negative) history of disease.

[Epidemiology and burden of acute otitis media in Valencia (Spain)]. / Epidemiología e impacto de la otitis media aguda en la Comunidad Valenciana.

OBJECTIVE: To assess the burden (incidence, treatment and complications) of acute otitis media (AOM) and otitis media with effusion (OME) in children younger than 5 years of age from Valencia, Spain. SUBJECT AND METHODS: We performed a retrospective cohort study of 1,399 children followed-up for the first 5 years of life. Seventeen pediatricians reviewed the medical records of their patients born in 1995 and 1996 and followed-up from birth until the age of 5 years. For each child, the number of otitis episodes, treatment, complications, and surgical interventions was obtained. RESULTS: There were 2,961 episodes of AOM in the first 5 years of life (2.23 cases/child). Four hundred seventy-six cases (16.1 %) occurred before 1 year of age and 1,346 between the first and second year of life (45.5 %). By the third year of life, 59.8 % had had at least one episode. In most children (80.9 %), diagnosis was made in primary care and required a median of 1.81 visits/episode for follow-up. A total of 94.5 % were treated with antibiotics (amoxicillin-clavulanate 38.8 %, cefuroxime 14.3 %, clarithromycin 8.2 % and amoxicillin 5.9 %) and 8.5 % required a change of antibiotic therapy. Two hundred seventeen children (15.2 %) had at least one episode of OME. Twenty-six patients (1.8 %, 95 % CI: 1.2-2.7 %) required insertion of ventilation tubes. Twenty-four patients (1.7 %) had secondary hypoacusis. There was one case of meningitis and two cases of chronic otorrhea. No cases of mastoiditis were recorded. CONCLUSIONS: The incidence of AOM in Valencia is 40,014 episodes/100,000 children younger than 5 years/year (95 % CI: 39,700-40,300). It represents a significant burden due to the large number of visits, antibiotic use, associated surgical procedures and need for auditory rehabilitation.

Distinct patterns of word retrieval in right and left frontal lobe patients: a multidimensional perspective.

Several studies have shown that patients with frontal lobe damage (FL) generate fewer words than control participants in verbal fluency tasks. In the current study, we were interested in assessing the quality of such verbal fluency data. Multidimensional exploratory techniques, namely, hierarchical clustering (HC) and correspondence analysis (CoA), were performed on verbal fluency data collected from 13 FL patients and 11 age-matched controls. HC of individual word-profiles distinguished between patients with left frontal lobe (LFL) and right frontal lobe (RFL) lesions. CoA revealed that LFL patients generated unusual word-profiles, as evidenced by their peripheral location on a CoA map, while RFL patients produced highly typical word-profiles. We would like to suggest that preserved functioning of the left frontal lobe might have constrained the responses of the RFL group resulting in typical word combinations, whereas preserved right frontal lobe functioning might have mediated greater diversification in the responses of the LFL group. The present study shows that HC and CoA can be applied to neuropsychological data to reveal complex relationships between cognitive performance and cerebral lesion sites.

Verbal and design fluency in patients with frontal lobe lesions.

The ability to generate items belonging to categories in verbal fluency tasks has been attributed to frontal cortex. Nonverbal fluency (e.g., design fluency) has been assessed separately and found to rely on the right hemisphere or right frontal cortex. The current study assessed both verbal and nonverbal fluency in a single group of patients with focal, frontal lobe lesions and age- and education-matched control participants. In the verbal fluency task, participants generated items belonging to both letter cues (F, A, and S) and category cues (animals and boys' names). In the design fluency task, participants generated novel designs by connecting dot arrays with 4 straight lines. A switching condition was included in both verbal and design fluency tasks and required participants to switch back and forth between different sets (e.g., between naming fruits and furniture). As a group, patients with frontal lobe lesions were impaired, compared to control participants, on both verbal and design fluency tasks. Patients with left frontal lesions performed worse than patients with right frontal lesions on the verbal fluency task, but the 2 groups performed comparably on the design fluency task. Both patients and control participants were impacted similarly by the switching conditions. These results suggest that verbal fluency is more dependent on left frontal cortex, while nonverbal fluency tasks, such as design fluency, recruit both right and left frontal processes.

Anterior cingulate metabolism correlates with stroop errors in paranoid schizophrenia patients.

UNLABELLED: Using [O-15]-H(2)O PET Carter et al. (1997) reported that medicated patients with schizophrenia performing computerized single trial Stroop (1935) showed a reduction in the anterior cingulate activation response to the more attention demanding, incongruent Stroop condition. In that study, both patients and controls also showed a direct correlation between anterior cingulate activation and errors committed during incongruent trials of the task. In this study we follow up with an examination of paranoid schizophrenia outpatients and controls with very high resolution positron emission tomography (PET) and the longer half-life tracer [F-18]-fluorinated deoxyglucose (FDG) (Valk et al. 1990). All subjects (10 controls and 9 paranoid schizophrenia patients) were studied with FDG-PET while performing a computerized trial-by-trial version of the Stroop task during the uptake phase of the tracer (Carter et al. 1992). RESULTS: As in previous studies using the single trial Stroop, patients were able to perform the task but made more color-naming errors during incongruent trials than controls. The patients in the present study showed a trend towards increased metabolic activity in the right anterior cingulate cortex. In the patient group, but not in controls, the anterior cingulate glucose metabolic rate correlated positively with the total incongruent trial errors. CONCLUSION: These results are consistent with the hypothesis that the anterior cingulate plays a performance-monitoring role during human cognition. This study does not rule out a reduction in error sensitivity in this region of the brain in schizophrenia, as other studies have suggested, however the data show that in unmedicated patients with the paranoid subtype this function is preserved to some extent.

Mapping symbols to response modalities: interference effects on Stroop-like tasks.

Response compatibility effects were assessed with a Stroop-like task which involved arrow and word stimuli. The subjects were required to respond to one stimulus--an arrow (e.g.,-->) or a word (e.g., left)--and ignore the other. It was shown that response compatibility played a significant role in generating Stroop-like interference. Robust interference effects were observed when the subjects responded manually to word stimuli (ignoring irrelevant arrows) and when they responded vocally to arrow stimuli (ignoring irrelevant words). Smaller interference effects were observed under response-compatible conditions, namely, responding manually to arrows and vocally to words. In the second experiment, within-dimension displays (e.g., arrow-arrow or word-word displays) yielded a pattern of interference that did not interact with response modality. These findings indicate that both stimulus-response compatibility effects and target-distractor similarity are crucial for understanding Stroop-like interference.

Letter and category fluency in patients with frontal lobe lesions.

This study examines the hypothesis that patients with frontal lobe lesions are impaired on tests of letter but not category fluency. This hypothesis was proposed by Moscovitch (1994), based on a series of cognitive studies with young, normal participants. A group of patients with lateral prefrontal lesions and age-matched controls were tested on 2 tests of verbal fluency, the FAS task and a category fluency task that used semantic categories as cues (e.g., animals). Patients with frontal lobe lesions generated fewer items than controls on both letter and category fluency. This effect did not interact with the type of fluency test, suggesting that the frontal lobes are more generally involved in verbal fluency. Moreover, this pattern of findings, along with previous results of impaired free recall and remote retrieval in this patient group, suggests that patients with frontal lobe lesions do not efficiently organize and develop retrieval strategies.

Is the cerebellum involved in learning and cognition?

Current studies are examining whether the cerebellum has a functional role in non-motor tasks using both behavioral and physiological methods with animals, and computer simulations of a classical conditioning task. Cerebellar involvement in cognition has been assessed in studies with healthy and neurologically impaired humans. The results have led to new hypotheses that are providing testable predictions about the role of the cerebellum in perception, attention, and other cognitive functions.

2-Fluoro-ATP, a fluorinated ATP analog. 19F nuclear magnetic resonance studies of the 2-fluoro-ADP . myosin subfragment-1 complex.

The synthesis of a fluorinated ATP analog, 2-fluoro-ATP (2-flATP), is described. This analog is designed for 19F nuclear magnetic resonance (NMR) studies of large enzymes and proteins which bind adenine nucleotides. 2-flATP is shown to be active as an ATP analog in a number of enzyme systems, and its 19F-NMR properties are determined. Specifically the principal elements of the 19F-NMR chemical shift tensor are shown to be 104, 12, and -116 ppm. The complex between 2-flADP and the myosin subfragment-1 ATPase is studied by 19F NMR, comparing the normal Michaelis complex and 2-flADP "trapped" on subfragment-1. These complexes are shown to be indistinguishable from the standpoint of the environment and mobility of the adenine ring.

Lysozyme catalysis: kinetics of the hydrolysis of cell wall oligosaccharides.

The cleavage of cell wall tetrasaccharide, the beta(1 leads to 4)-linked dimer of the basic repeating disaccharide N-acetyl-D-glucosamine-beta(1 leads to 4)-N-acetyl-D-muramic acid, by lysozyme has been studied at various concentrations of lysozyme and over long time ranges. A theoretical analysis of the kinetic results indicates that direct hydrolysis of the tetrasaccharide by binding in subsities CDEF of the active site of lysozyme is significant at long times relative to the transglycosylation pathway. The binding constant for tetrasaccharide in CDEF is shown to be 10(3) times larger than that determined on the basis of an analysis of kinetic data over a more restricted range of times and concentrations.

The nuclear magnetic resonance determination of the conformation of saccharides bound in subsite D of lysozyme.

The binding of the trisaccharide (2-acetamido-2-deoxy-D-muramic acid)-beta(1 leads to 4)-(2-aceta-mido-2-deoxy-D-glucosyl)-beta(1 leads to 4)-(2-acetamido-2-deoxy-D-muramic acid) to subsites B, C, and D in lysozyme has been studied by 1H nuclear magnetic resonance methods. In particular, the coupling constant between H1 and H2 of the reducing saccharide bound in subsite D has been determined. The coupling constant for the bound saccharide indicates that the dihedral angle between C1 and C2 for the reducing saccharide is not significantly changed upon binding to lysozyme. This result is discussed in terms of other evidence for the role of distortion of the saccharide bound in subsite D in the lysozyme-catalyzed hydrolysis of cell wall oligosaccharides.

The stepwise binding of small molecules to proteins. Nuclear magnetic resonance and temperature jump studies of the binding of 4-(N-acetylaminoglucosyl)-N-acetylglucosamine to lysozyme.

The binding of 4-(N-acetylaminoglucosyl)-N-acetylglucosamine to lysozyme was studied by both nuclear magnetic resonance (NMR) and temperature-jump methods under comparable conditions. The NMR measurements on the inhibitor spectrum were carried out over a range of inhibitor concentrations including levels at which most of the inhibitor was bound to the enzyme. Data in this region were obtained by a novel difference method in conjunction with correlation spectroscopy. The results from the combination of both experimental techniques demonstrated the existence of a two-step binding mechanism and produced both values for all of the individual rate constants and also the NMR spectral data for the inhibitor in the two enzyme-inhibitor complexes. The later data characterize the environment experienced by the inhibitor at each stage in the binding process and thus provides both a three-dimensional and a dynamic picture of the interaction.