Influência do tamanho e da rigidez dos objetos nos ajustes proximais e distais do alcance de lactentes / Influence of object size and rigidity on proximal and distal adjustments to infant reaching

CONTEXTUALIZAÇÃO: Estudos têm identificado que as propriedades dos objetos induzem os ajustes no alcance; no entanto, poucos investigaram a influência específica do tamanho e rigidez dos objetos em lactentes jovens. OBJETIVO: Verificar se lactentes de 4 a 6 meses realizam ajustes proximais e distais ao alcançarem objetos de diferentes tamanhos e rigidez. MÉTODOS: Nove lactentes saudáveis foram posicionados em uma cadeira inclinada a 50º. Quatro objetos foram apresentados, um rígido grande (RG), um rígido pequeno (RP), um maleável grande (MG) e um maleável pequeno (MP), por um período de 1 minuto cada. Em um total de 384 alcances, foram analisados os ajustes proximais (alcance uni e bimanual) e distais (orientação da mão horizontal, vertical e oblíqua; mão aberta, fechada e semi-aberta) e o sucesso do alcance dos objetos. RESULTADOS: Constatou-se ajuste bimanual para o objeto RG e unimanual para os demais. A orientação da mão oblíqua foi predominante no toque dos objetos, enquanto para a preensão dos mesmos, a predominância foi a vertical, principalmente para o objeto RG. A orientação horizontal não foi observada na preensão do objeto RG. A mão semi-aberta foi mais freqüente no início do alcance para todos os objetos, enquanto no toque do objeto RG a mão aberta foi predominante. O sucesso do alcance foi maior para os objetos maleáveis (MG, MP) do que para os rígidos (RG e RP). CONCLUSÃO: Lactentes jovens estudados são capazes de planejar e ajustar seus movimentos baseados na percepção das propriedades físicas dos objetos, o que sugere interação percepção-ação.

BACKGROUND: Studies have identified that object properties lead to adjustments to reaching. However, few have investigated the specific influence of object size and rigidity among young infants. OBJECTIVE: To verify whether four to six-month-old infants make proximal and distal adjustments when reaching for objects of different sizes and rigidity. METHOD: Nine healthy infants were seated on a chair inclined at 50º. Four objects were presented to them: one large rigid (LR), one small rigid (SR), one large malleable (LM) and one small malleable object (SM), each for a one-minute period. A total of 384 reaches were analyzed to verify proximal adjustments (single-hand and two-hand reaching) and distal adjustments (horizontal, vertical and oblique hand orientation; opened, closed and half-open hand), and the success in reaching the objects. RESULTS: The infants exhibited two-hand adjustments for the LR object and single-hand adjustments for the other objects. Oblique orientation was predominant for touching the objects, while vertical orientation was predominant for grasping them, particularly the LR object. Horizontal orientation was not observed for grasping the LR object. At the start of reaching for all objects, the hands were most frequently half-open, while the hands were predominantly open when touching the LR object. Success was greater when reaching for malleable objects (LM, SM) than for rigid objects (LR and SR). CONCLUSION: The young infants studied were capable of planning and adjusting their movements on the basis of their perceptions of the physical properties of the objects, which suggests that perception-action interaction was occurring.

Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat

Several studies demonstrate that, within the ventral medullary surface (VMS), excitatory amino acids are necessary components of the neural circuits involved in the tonic and reflex control of respiration and circulation. In the present study we investigated the cardiorespiratory effects of unilateral microinjections of the broad spectrum glutamate antagonist kynurenic acid (2 nmol/200 nl) along the VMS of urethane-anesthetized rats. Within the VMS only one region was responsive to this drug. This area includes most of the intermediate respiratory area, partially overlapping the rostral ventrolateral medulla (IA/RVL). When microinjected into the IA/RVL, kynurenic acid produced a respiratory depression, without changes in mean arterial pressure or heart rate. The respiratory depression observed was characterized by a decrease in ventilation, tidal volume and mean inspiratory flow and an increase in respiratory frequency. Therefore, the observed respiratory depression was entirely due to a reduction in the inspiratory drive. Microinjections of vehicle (200 nl of saline) into this area produced no significant changes in breathing pattern, blood pressure or heart rate. Respiratory depression in response to the blockade of glutamatergic receptors inside the rostral VMS suggests that neurons at this site have an endogenous glutamatergic input controlling the respiratory cycle duration and the inspiratory drive transmission.

Cardiorespiratory alterations produced by pharmacological agents applied to the ventrolateral medulla (intermediate area) of the cat: effect of exercise condition on glycine-induced inhibition

1. To study the action of the intermediate area (IA), coextensive with the rostral ventrolateral medulla, on the neurophysiological mechanisms involved in the regulation of respiration, in terms of inspiratory drive and respiratory timing, cats were submitted to topical application of sodium pentobarbital (30 mg/ml), leptazol (200 mg/ml), glutamate (50 mg/ml) and glycine (100 and 50 mg/ml) to the IA. The effects of electrically induced exercise on the ventilatory response and oxygen uptake (VO2) obtained by topical application of glycine (50 mg/ml) to the IA were also studied. 2. Leptazol reduced minute ventilation (VE) and inspiratory drive (VT/TI) and changed the timing mechanism. Glutamate only increased tidal volume (VT), VE and VT/TI. Arterial blood pressure (AP) increased and heart rate (HR) did not change with either drug. 3. Sodium pentobarbital reduced VT and changed the timing mechanism. Glycine only reduced VE, VT and VT/TI. AP decreased and HR did not change with either drug. 4. The depressor effects of glycine on respiratory pattern, VO2 and CO2 production (VCO2) tended to be attenuated by exercise. 5. The fall in AP due to glycine application did not differ between resting and exercise conditions. 6. Our results indicate that at least two different nervous structures are involved in the IA: one responsible for the respiratory drive and sensitive to glycine and glutamate, and the other responsible for the regulation of the timing mechanism and sensitive to sodium pentobarbital and leptazol

Silicose em cavadores de pocos. / Silicosis in well diggers

Sao apresentados 24 casos de silicose em cavadores de pocos cuja idade media era de 44 anos (29 a 58). Todos eram sintomaticos sendo os sintomas mais comuns a dispneia e a tosse. Todos apresentaram lesoes radiologicas, predominando a fibrose pulmonar nos lobos superiores. O eletrocardiograma mostrou sobrecarga de camara direita em tres casos, bloqueio de ramo direito em dois, sendo normal em 19 casos.A espirometria revelou um disturbio funcional misto em 12 casos, restricao pura em cinco, obstrucao pura em tres e foi normal em quatro casos