Anaemia, iron and vitamin deficits in patients with peripheral arterial disease.

INTRODUCTION: Anaemia can compromise muscle and organ function. Related iron and vitamin body stores have seldom been assessed in patients with peripheral arterial disease. REPORT: We retrospectively analysed basal prevalence of anaemia, iron, B(12)-vitamin and folic acid deficits in 420 patients with claudication and 204 patients with critical limb ischaemia (CLI). The prevalence of the evaluated parameters was 9.8%, 6.7%, 6.7% and 2.9% among patients with claudication but 49.5%, 31.9%, 15.7% and 6.4% among CLI patients, respectively (p < 0.05 for all). DISCUSSION: Anaemia, iron and vitamin deficits are uncommon among patients with ischemic claudication but very prevalent among patients with CLI.

Excitatory and inhibitory lateral interactions effects on contrast detection are modulated by tRNS.

Contrast sensitivity for a Gabor signal is affected by collinear high-contrast Gabor flankers. The flankers reduce (inhibitory effect) or increase (facilitatory effect) sensitivity, at short (2λ) and intermediate (6λ) target-to-flanker separation respectively. We investigated whether these inhibitory/facilitatory sensitivity effects are modulated by transcranial random noise stimulation (tRNS) applied to the occipital and frontal cortex of human observers during task performance. Signal detection theory was used to measure sensitivity (d') and the Criterion (C) in a contrast detection task, performed with sham or tRNS applied over the occipital or the frontal cortex. After occipital stimulation results show a tRNS-dependent increased sensitivity for the single Gabor signal of low but not high contrast. Moreover, results suggest a dissociation of the tRNS effect when the Gabor signal is presented with the flankers, consisting in a general increased sensitivity at 2λ where the flankers had an inhibitory effect (reduction of inhibition) and a decreased sensitivity at 6λ where the flankers had a facilitatory effect on the Gabor signal (reduction of facilitation). After a frontal stimulation, no specific effect of the tRNS was found. We account for these complex interactions between tRNS and flankers by assuming that tRNS not only enhances feedforward input from the Gabor signal to the cortex, but also enhances the excitatory or inhibitory lateral intracortical input from the flankers. The boosted lateral input depends on the excitation-inhibition (E/I) ratio, namely when the lateral input is weak, it is boosted by tRNS with consequent modification of the contrast-dependent E/I ratio.

Protective effect of quercetin against in vitro erythrocyte rheology alterations produced by arsenic.

Humans are exposed to heavy metals such as arsenic (As), through contaminated food and drinking water. The effect of As on RBC membrane is one of the most important biological effects. In a previous work, we have studied the AsVin vitro effect on erythrocytes biophysical properties discovering alterations regarding aggregability deformability, cell morphology, membrane fluidity and osmotic response. We have also observed that the presence of the metal produces an oxidative stress in RBCs that might be the origin of rheological impairment. In the present work we analyzed RBCs rheological properties associated with membrane fluidity and lipid peroxidation in presence of As and quercetin (Qc). From our results we can conclude that RBCs treatment with Qc is efficient to prevent the impairment of the mechanical properties of the cell membrane produced by the As, through oxygen reactive agents in the membrane structure, mainly on the lipids. This protective effect is observed in the preservation of the erythrocytes rheological properties and consequently in the maintenance of an appropriate blood flow, specially in the small vessels in the peripheral circulation.

Spatial filtering and spatial primitives in early vision: an explanation of the Zöllner-Judd class of geometrical illusion.

The apparent length and orientation of short lines is altered when they abut against oblique lines (the Zöllner and Judd illusions). Here we present evidence that the length and orientation biases are geometrically related and probably depend upon the same underlying mechanism. Measurements were done with an 'H' figure, in which the apparent length and orientation of the cross-bar was assessed by the method of adjustment while the orientation of the outer flanking lines was varied. When the flanking lines are oblique the apparent length of the central line is reduced and its orientation is shifted so that it appears more nearly at right-angles to the obliques than is in fact the case. Measurements of the orientation and length effects were made in three observers, over a range of flanking-line angles (90, 63, 45, 34 and 27 deg) and central line lengths (9, 17, 33 and 67 arc min). The biases increased with the tilt of the flanking-lines, and decreased with central line length. The extent of the length bias could be accurately predicted from the angular shift by simple trigonometry. We describe physiological and computational models to account for the relation between the orientation and length biases.

Visual selective attention and reading efficiency are related in children.

We investigated the relationship between visual selective attention and linguistic performance. Subjects were classified in four categories according to their accuracy in a letter cancellation task involving selective attention. The task consisted in searching a target letter in a set of background letters and accuracy was measured as a function of set size. We found that children with the lowest performance in the cancellation task present a significantly slower reading rate and a higher number of reading visual errors than children with highest performance. Results also show that these groups of searchers present significant differences in a lexical search task whereas their performance did not differ in lexical decision and syllables control task. The relationship between letter search and reading, as well as the finding that poor readers-searchers perform poorly lexical search tasks also involving selective attention, suggest that the relationship between letter search and reading difficulty may reflect a deficit in a visual selective attention mechanisms which is involved in all these tasks. A deficit in visual attention can be linked to the problems that disabled readers present in the function of magnocellular stream which culminates in posterior parietal cortex, an area which plays an important role in guiding visual attention.

Molecular analysis of p53 tumor-suppressor gene and microsatellites in preneoplastic and neoplastic lesions of the colon and esophagus.

Mutations in exons 4-8 of the p53 gene by the PCR-SSCP analysis in preneoplastic and neoplastic lesions of the colon (n=11) and esophagus (n=18) were screened. p53 overexpression by immunohistochemistry in 11 colonic lesions and 13 microsatellites, in all the patients (n=29), were also studied. A positive result concordancy between the three techniques was found in 1 adenoma and 2 adenocarcinomas of the colon, each with loss of heterozygocity of microsatellites. Metaplastic lesions of esophagus showed biallelic mutations and low frequency of microsatellite alterations. The relationship between genetic alterations in p53, microsatellites and type of colon and esophageal lesions is discussed.

A visual evoked potential correlate of global figure-ground segmentation.

Human observers discriminated the global orientation of a texture-defined figure which segregated from a texture surround. Global figure discriminability was manipulated through within-figure collinearity, figure-surround interaction, and figure connectedness, while the local orientation contrast at edges between figure and surround was kept constant throughout all the experiments. Visual evoked potentials (VEPs) were recorded during onset-offset stimulation in which the figure cyclically appeared and disappeared from a uniform texture background. A difference component was obtained by subtraction of offset-from onset-VEP. Two negative peaks of the difference component are found with latencies around 140-160 and 200-260 ms, respectively. Enhanced discriminability of the global figure reduced (11-25 ms) the latency of the second peak, hence indicating that the 200-260 ms component was produced by global figure-ground segmentation.

Discrimination of an orientation difference in dynamic textures.

We investigated whether the response of a motion sensor was related to the specificity of sensory information (orientation and direction of motion) used to compute motion energy. This was done in two ways. First, we assessed whether orientation discrimination of a target line, which segregated by an orientation difference from a textured background, was improved with two-frame apparent motion stimulation (as compared with static presentation). Second, we investigated whether the amount of improvement (in either orientation or direction of motion discrimination) depends on a particular combination of target orientation and direction of motion (either orthogonal or parallel). We found that the percentage of correct responses in the discrimination task (a) was higher for a moving target than for a static one; (b) was higher when the target was oriented more orthogonally to motion direction than background elements; (c) was little affected by background motion and (d) decreased with frame duration in the direction of motion task whereas it was largely unaffected by frame duration in the discrimination of orientation task. These results suggest that discrimination of moving texture boundaries is based on a motion sensor tuned to a particular combination of orientation and direction of motion, which is capable of signalling the orientation of a moving target more accurately than a static sensor.

The detection of deviation from straightness in lines.

A wide range of differently shaped perturbations were introduced into long thin straight lines, and threshold amplitude for their detection was measured. This amplitude threshold varies over a 20-fold range, depending on the shape of the cue, but can be economically expressed as just one numerical value, irrespective of the cue shape. This quantity is the area of the largest bump in the target around a least squares regression line axis, and its value is 0.3 arc min2. This value can be related to a fundamental spatial error of 3 arc sec (standard deviation) which is the limiting constraint on shape sensitivity.

High prevalence of vitamin D insufficiency in healthy elderly people living at home in Argentina.

OBJECTIVE: To evaluate the nutritional status of vitamin D in urban populations of healthy elderly people living at home, in different regions of Argentina. DESIGN: Cross-sectional study. SUBJECTS: In total, 386 ambulatory subjects over 65 y of age from seven cities (between latitude 26 degrees S and 55 degrees S) were asked to participate between the end of winter and the beginning of spring. Of these, 369 accepted, 30 were excluded because of medical history or abnormal biochemical determinations. Finally, 339 subjects (226 women and 113 men) (X+/-s.d.) (71.3+/- 5.2 y) were included. RESULTS: Serum 25OHD levels were lowest in the South (latitude range: 41 degrees S-55 degrees S): 14.2+/-5.6 ng/ml (P<0.0001vs North and Mid regions); highest in the North (26 degrees S-27 degrees S): 20.7+/-7.4 ng/ml (P<0.03 vs Mid, P<0.0001vs South); and intermediate in the Mid region (33 degrees S-34 degrees S) 17.9+/-8.2 ng/ml. Serum mid-molecule PTH (mmPTH) and 25OHD were inversely related: (r=-0.24, P<0.001). A cutoff level of 25OHD at which serum mmPTH levels began to increase was established at 27 ng/ml. A high prevalence (87-52%) of subjects with 25OHD levels in the deficiency-insufficiency range (25OHD levels <20 ng/ml) was detected. CONCLUSION: This study shows that vitamin D deficiency/insufficiency in the elderly is a worldwide problem. Correction of this deficit would have a positive impact on bone health of elderly people.

The treatment of Paget's bone disease with sodium ethidronate.

Of 58 patients with Paget's disease treated with disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) in doses of 20 and 10 mg/kg/day, a group of 20 patients with the oligostotic form of the disease showed a significantly greater incidence of complications, such as worsening of bone pains, when compared with a group of 38 patients with the polyostotic disease (P less than 0.05). The group of 32 patients that received 20 mg/kg/day showed a greater although not significant incidence of clinical complications than the group of 26 patients treated with 10 mg/kg/day. Bone biopsies performed in one polyostotic and three oligostotic cases who suffered episodes of bone pain worsening during treatment with 20 mg/kg/day disclosed a severe osteomalacia. Both groups treated with 20 and 10 mg/kg showed a highly significant decrease of urinary hydroxyproline (THP) excretion and of serum alkaline phosphatase (P less than 0.01) after two and six months of treatment although the trend comparison between doses was not significant. It is suggested that the dose of EHDP should be related to the extent of the disease.

[Evaluation of clinical and humoral data in 148 patients with Piaget's bone disease]. / Osteitis deformante de Paget. Manifestaciones clínicas y humorales en 148 pacientes.

Pain was present in 113 out of a total of 148 patients with Paget's bone disease who were evaluated. The symptom was originated by: a) bone, in 56.6 % of the cases; b) joints, in 32.7 %; c) skull compression in 7.1 % and spine compression in 3.5 % of the cases. Bone deformities were seen in 50.7 % of patients. Of this total, 41.4 % were localized in femorae. Pathological fractures were found in 16.9 % of patients. Of this total, 44.0 % were localized in femore and 19.2 % in the humerae. The localization of Paget's bone disease in the humerus appears to be specially risky due to the high percentage of fractures found in the present study as well as the frequency of the sarcomatous degeneration described in the literature. Two patients (1.4 %) developed an osteogenic sarcoma in bones previously affected by Paget's disease. It was localized in the tibia in one case and in iliac bone in the other. Frequent associated diseases were osteoporosis, verified in 31.8 % of the patients, arthritis deformans in 28.6 % and nephrolithiasis, verified in 31.8 % of the patients, arthritis deformans in 28.6 % and nephrolithiasis in 12.2 %. Associated neoplastic diseases were mammary cancer in 6.5 % of 77 women and colonic cancer in 2.0 of 148 patients of both sexes. The diagnosis has been made previously or during the period of the present study. The effects of the extent of Paget's bone disease as well as the effect of Paget's skull complication on serum alkaline phosphatase and urinary total hydroxyproline were investigated. Serum alkaline phosphatase and urinary total hydroxyproline were higher in polyostotic then in oligostotic patients although the difference was not significant for serum alkaline phosphatase in a group of 50 polyostotic with skull lesions versus 16 oligostotic with skull lesions. There was a significant increase of serum alkaline phosphatase in groups of 29 polyostotic without skull lesions versus 45 oligostotic without skull lesions (p < 0.001) and in groups of 50 polyostotics with skull lesions versus 29 polyostotics with skull lesions (p < 0.05), and of 16 oligostotic withh skull lesions versus 45 oligostotics without skull lesions (p < 0.02). There was a significant increase of urinary total hydroxyproline in a group of 46 polyostotics with skull lesions versus 15 oligostotics with skull lesions (p < 0.01) and of 25 polyostotics without skull lesions versus 41 oligostotics without skull lesions (p < 0.001), as well of 46 polyostotics with skull lesions versus 25 polyostotics without skull lesions (p < 0.005) and 15 oligostics with skull lesions versus 41 oligostotics without skull lesions (p < 0.02). Although the differences should be referred to a greater number of patients, the results suggest that the effects of Paget skull lesions are more evident on serum alkaline phosphatase than on urinary total hydroxyproline.

Visual search of good and poor readers: effects with targets having single and combined features.

This study examined differences between normal and poor readers in the visual-search strategy used to detect a target shape in a background of similar shapes. No differences between the two groups occur in search for simple features (Exps. 1 and 3) and conjunction of features (Exp. 2). However, the performance of the two groups differ on search tasks with multifeatured shapes, in which targets and nontargets differ in both the identity of features and their spatial relationship or in the spatial relationship of features alone. Results suggest that, rather than a problem in searching complex stimuli, poor searchers have difficulty within stimuli like letters and geometrical shapes which require integration of features within a module of the visual system.

Visual search for single and combined features by children and adults: possible developmental inferences.

Visual search time was measured in four groups of children 4 to 10 years of age and in young adults, as a function of display size for both target present and target-absent conditions. The slopes of regression lines in a simple search (search for \ within /) were compared with those obtained in within-dimension conjunction target searches, within either homogeneous (search for the inverted T within Ts) or heterogeneous distractors (search for arrow within Ys and inverted Ys). Analysis indicated that simple search was always preattentive (slopes near 0) after 5 years of age and serial (with positive slopes) before this age. Searching within heterogeneous distractors apparently involved element-by-element scrutiny and focal attention in all groups whereas searching within homogeneous distractors required distributed attention, perhaps based on parallel grouping of distractors in adults, though distractors were focally attended to by children.

Psychophysical and electrophysiological evidence of independent facilitation by collinearity and similarity in texture grouping and segmentation.

Gestalt factors of collinearity and similarity facilitate two fundamental perceptual tasks: grouping elements into figures and segmentation of figures from the ground. We have used a global-local paradigm to examine the psychophysical and neural correlates of these processes in humans: observers discriminated between orientations of either a three-Gabor group (grouping), or of a central Gabor within the group (segmentation). Groups were centered on a background of differently oriented Gabors. In both tasks, accuracy was increased by the collinearity (Experiment 1) and similarity (Experiment 2) of elements within the three-Gabor group. ERP correlates of facilitation differed across tasks. For segmentation, they were indexed by increased amplitude of negative ERP components, specific for processing textures, peaking at 75-250 and 150-250 ms, respectively. For grouping, collinearity and similarity had different effects. Collinearity produced a positive polarity deflection between 40 and 179 ms (i.e. the opposite to segmentation). This task-dependent switch in sign of polarity change, without corresponding changes in the stimulus or perception, reflects distinct neural mechanisms for collinear facilitation in grouping and segmentation. In contrast, similarity reduced positivity at 275 ms. Results show similar modulation of segmentation components via the distinct mechanism underlying collinearity and similarity, but distinct modulation of grouping components via collinearity and similarity.