Effects of regular exercise and dual tasking on spatial and temporal parameters of obstacle negotiation in elderly women.

This study investigated the effects of regular exercise and dual tasking on bilateral spatial and temporal parameters of obstacle negotiation in elderly women. Sedentary (n=12) and physically active (n=12) elderly women volunteered to participate in this study. Gait kinematics were recorded during obstacle crossing when performing a dual task and when not performing a dual task. Physically active participants crossed obstacles more safely, in terms of clearance or distance to or over the obstacle, both with and without dual tasking, and usually for both lead and trail legs. Performing the dual task increased toe distance, and decreased heel distance and gait speed in the active participants, and increased toe clearance and heel distance, and decreased gait speed in the sedentary participants. Differences between preferred and non-preferred leg were accentuated for toe clearance in the lead limb. These results suggest that specialized exercises may not be needed for improvement in obstacle avoidance skills in the elderly, and participation in multi-activities, including aerobic exercises, may be sufficient.

Evaluation of the effectiveness of mass trapping with BG-sentinel traps for dengue vector control: a cluster randomized controlled trial in Manaus, Brazil.

The objective of this study was to assess the effectiveness of BG-Sentinel (BGS) traps for mass trapping at the household level to control the dengue vector, Aedes aegypti (L.), in Manaus (Brazil) by performing a cluster randomized controlled trial. After an initial questionnaire and baseline monitoring, 6 out of 12 clusters were randomly allocated to the intervention arm, where participating premises received one BGS trap for mass trapping. The other six clusters did not receive traps and were considered as the control arm. Biweekly monitoring with BGS in both arms assessed the impact of mass trapping. At the end of the study, a serological survey was conducted and a second questionnaire was conducted in the intervention arm. Entomological monitoring indicated that mass trapping with BGS traps significantly reduced the abundance of adult female Ae. aegypti during the first five rainy months. In the subsequent dry season when the mosquito population was lower, no effect of mass trapping was observed. Fewer Ae. aegypti females were measured in the intervention arm during the next rainy period, but no significant difference between arms was observed. The serological survey revealed that in participating houses of mass trapping areas recent dengue infections were less common than in control areas, although this effect was not statistically significant. The majority of participants responded positively to questions concerning user satisfaction. Our results suggest that BGS traps are a promising tool which might be deployed as part of dengue control programs; however, further investigations and larger scale studies are necessary.

Dental trauma among Brazilian schoolchildren: prevalence, treatment and associated factors.

AIM: To assess the prevalence of traumatic dental injury (TDI), as well as associated factors, behaviour of affected schoolchildren and normative treatment needs. METHODS: The present cross-sectional study involved 590 children aged 7-14 years at state schools in Campina Grande, Brazil. The O'Brien classification [1994] was used for the diagnosis of TDI and the body mass index (BMI) was used as an indicator of overweight/obesity. Clinical tests were carried out by two duly calibrated examiners (intra-observer and inter-observer agreement: 0.87 and 0.90, respectively). The Chi-square test was used (5% level of significance) to determine whether TDI was associated with age, gender, ethnicity, overweight/obesity, lip seal and overjet. Backward stepwise multivariate regression analysis was performed. Normative treatment needs were determined based on the criteria of the International Association of Dental Traumatology (IADT). When the absence of treatment was detected, each child/adolescent was asked about the reason for non-treatment. RESULTS: The prevalence of TDI was 12.7%. The most common type of trauma was enamel fracture (67.0%), followed by enamel-dentine fracture (25.3%). TDI was 4.9-fold greater (95% CI: 1.6-14.4) among children aged 13 and 14 years, 1.9- fold greater (95% CI: 1.1-3.2) among males and 2.6-fold greater (95% CI: 1.2-5.4) among those with inadequate lip seal. The majority of schoolchildren did not undergo treatment (82.6%) due to a belief that it was unnecessary (53.2%). The normative clinical evaluation revealed that adhesive restoration was the most common form of treatment (84.0%). CONCLUSION: The prevalence of TDI was low. Age, gender and inadequate lip seal were associated with dental trauma. A significant number of schoolchildren did not receive treatment for dental trauma.

[Common orthopedic problems in adolescents] / Problemas ortopédicos comuns na adolescência.

OBJECTIVE: Orthopedic problems in children and adolescents are quite frequent. For that reason, our aim was to give a remarkable insight into five selected topics: spinal deformities, osteochondritis, growing pains, back pain, and corrective shoes. METHODS: We analyzed general concepts of spinal deformities, including the general definition of scoliosis and its etiologic classification. We also discussed the definition, etiology, diagnosis, and treatment of osteochondritis, growing pains, back pain, and corrective shoes. The data were obtained from review articles, textbooks, and from the Internet. RESULTS: We describe the epidemiology, diagnosis, and treatment of the selected conditions through review of literature and the authors own experience. CONCLUSIONS: Comments and relevant aspects concerning general pediatric practice are discussed.

Low concentrations of the organophosphate VX affect spontaneous and evoked transmitter release from hippocampal neurons: toxicological relevance of cholinesterase-independent actions.

In the present study, the patch-clamp technique was applied to cultured hippocampal neurons to evaluate the effects of the nerve agent VX on evoked and spontaneous postsynaptic currents mediated by gamma-aminobutyric acid (GABA) and glutamate. At 0.01 nM, VX reduced the amplitude of evoked GABAergic currents, and only at concentrations >1 nM did it decrease the amplitude of evoked glutamatergic currents. The effect of VX on GABAergic currents, which was partially reversible upon washing of the neurons with VX-free external solution, could be prevented by the muscarinic antagonist atropine. In contrast, the effect of VX on glutamatergic currents, which was not reversible upon washing, appears to be related to the VX-induced reduction of the amplitude and frequency of repetitively firing by action potentials. In the presence of the Na(+)-channel blocker tetrodotoxin (TTX), VX (>/=10 nM) increased the frequency of GABA- and glutamate-mediated miniature postsynaptic currents (MPSCs). This effect of VX was unrelated to cholinesterase inhibition and was Ca(2+) dependent. The lack of effect of VX on MPSC kinetics indicates that VX-induced alterations of evoked and spontaneous currents are exclusively due to alterations of the transmitter release processes. The ability of VX to affect transmitter release in the brain may underlie some of its neurotoxic effects and may provide the basis for the development of therapeutic countermeasures to treat and/or prevent VX-induced neurotoxicity.

An analysis of low level doses of cholinesterase inhibitors in cultured neurons and hippocampal slices of rats.

Recent data indicate that the neurotoxic effects of organophosphate compounds, including those of the nerve agents VX and sarin, are not solely due to irreversible cholinesterase inhibition. In this study we applied the patch clamp technique to hippocampal neurons in culture and slices to investigate the effects of VX, sarin and huperzine A on transmitter release and the mechanisms related with such effects. The nerve agents VX and sarin at very low concentrations significantly reduced the evoked release of GABA and glutamate. This effect was dependent of the activation of muscarinic receptors. In the presence or absence of the Na(+)-channel blocker tetrodotoxin (TTX), VX increased the frequency of spontaneous glutamate and GABA-induced postsynaptic currents. The effect of VX on TTX-insensitive spontaneous currents appears to be unrelated to cholinesterase inhibition, because it could be detected even after cholinesterase was blocked by high concentrations of the nerve agent soman. The ability of the nerve gases to decrease evoked release of GABA and increase spontaneous transmitter release may underlie some of the neurotoxic effects of the compounds. Huperzine A did not affect spontaneous or evoked release of GABA and glutamate, suggesting that this compound may be a pure cholinesterase inhibitor and had no effect on postsynaptic GABAA or AMPA receptors.

Methamidophos: an anticholinesterase without significant effects on postsynaptic receptors or transmitter release.

Methamidophos (O,S-dimethyl phosphoroamidothiolate, Tamaron), an organophosphate (OP) anticholinesterase of limited toxicity, is widely used as an insecticide and acaricide. To provide additional insight into the molecular basis of its action, we have used electrophysiological and biochemical techniques to study the effects of methamidophos on the neuromuscular junction of rat and frog and on the central nervous system of rat. Methamidophos has a relatively weak inhibitory action on cholinesterases in rat diaphragm muscle, brain and hippocampal homogenates, with IC50 values on the order of 20-20 microM. An even weaker anticholinesterase activity was found in frog muscle homogenates, with the IC50 being above 300 microM. As further evidence of anticholinesterase activity, methamidophos (1-100 microM) was able to reverse the blockade by d-tubocurarine (0.5-0.7 microM) of neuromuscular transmission in rat phrenic nerve-hemidiaphragm preparations. Inhibition of cholinesterase activity by methamidophos was long lasting, which is consistent with the formation by the agent of a covalent bond with the enzyme's active serine residue. The action was also slowly reversible, which suggests spontaneous reactivation of the enzyme. electrophysiological studies at the rat neuromuscular junction showed that, due to its anticholinesterase activity, methamidophos increased the amplitude and prolonged the decay phase of nerve-evoked and spontaneous miniature end-plate potentials. In contrast to other OP compounds, e.g., paraoxon (Rocha et al., 1996a), methamidophos did not affect neurotransmitter release, nor did it interact directly with the muscle nicotinic acetylcholine receptor. Moreover, it contrast to paraoxon, methamidophos did not affect the whole-cell currents induced by application of acetylcholine, glutamate or gamma-aminobutyric acid recorded to cultured hippocampal neurons. Based on these data, methamidophos appears to have a selective effect on cholinesterase.

Paraoxon: cholinesterase-independent stimulation of transmitter release and selective block of ligand-gated ion channels in cultured hippocampal neurons.

Paraoxon (O,O-diethyl O-p-nitrophenyl phosphate) is the neurotoxic metabolite of the insecticide parathion (O,O-diethyl O-p-nitrophenyl phosphorothioate). The effects of organophosphorus compounds on peripheral synapses have been attributed to inhibition of cholinesterase and to direct actions on muscarinic and nicotinic receptors, but less is known about the actions of organophosphorus compounds, including paraoxon, in the central nervous system. We investigated initially the effects of paraoxon on spontaneous transmitter release by recording miniature postsynaptic currents (MPSCs) from cultured rat hippocampal neurons using the whole-cell mode of the patch-clamp technique. Paraoxon (0.3 microM) in the presence of tetrodotoxin (0.3 microM) and atropine (1 microM) caused a significant increase in the frequency of gamma-aminobutyric acid- and glutamate-mediated MPSCs, but did not change the peak amplitudes or decay-time constants of these MPSCs. In contrast, application of nicotinic agonists or antagonists did not change the MPSC frequency. The presynaptic effect of paraoxon shown here was not mediated by actions on muscarinic or nicotinic receptors, or by elevated acetylcholine levels secondary to inhibition of cholinesterase. In addition, agonists were applied to assess the postsynaptic effects of paraoxon on excitatory and inhibitory amino acid receptors. Paraoxon (30 microM-1 mM) blocked the ion channels of glycine, gamma-aminobutyric acidA, N-methyl-D-aspartic acid and nicotinic acetylcholine receptors, but not the ion channels of kalnate- and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors. The combined effects of paraoxon on spontaneous transmitter release and on the functions of several ligand-gated receptors may constitute mechanisms relevant to the neurotoxicity of paraoxon.

Diversity of nicotinic acetylcholine receptors in rat brain. V. alpha-Bungarotoxin-sensitive nicotinic receptors in olfactory bulb neurons and presynaptic modulation of glutamate release.

The presence of functional nicotinic acetylcholine receptors (nAChRs) on cultured neurons of the rat olfactory bulb was evaluated using the whole-cell patch-clamp technique. Application of acetylcholine (ACh) to 78% of the tested olfactory bulb neurons evoked whole-cell currents (referred to as direct response), which are very similar in characteristics to type IA currents. Their peak amplitude increased, while their rise-time and decay-time constants decreased with increasing agonist concentration. In 12% of the neurons, ACh evoked single or multiple miniature postsynaptic currents (referred to as indirect response) for which amplitude, rise time, and decay-time constants were not dependent upon the ACh concentration. Methyllycaconitine (1 nM), a selective competitive antagonist at the alpha-bungarotoxin-sensitive neuronal nAChR, reversibly blocked both responses, whereas 6-cyano-7-nitroquinoxaline-2,3-di-one (10 microM) reversibly blocked only the indirect responses. Whereas tetrodotoxin (0.2-2 microM) failed to affect the indirect response, Ca(+2)-free, Mg(+2)-containing external solution decreased reversibly and significantly the frequency of ACh-evoked miniature postsynaptic currents. The pharmacology and kinetics of the two types of responses are consistent with the existence in the olfactory bulb neurons of alpha-bungarotoxin-sensitive nAChRs at both postsynaptic and presynaptic sites, the presynaptic receptors being located on glutamatergic synapses where they modulate the release of the transmitter. The dimensions of the soma and dendrites of the neurons suggest that the direct response is obtained from periglomerular and/or granular neurons, and the indirect response from short-axon and/or external tufted cells. The present results suggest that 1) nicotinic synaptic transmission could play an important role in modulating the bulbar output at the glomerular level, and 2) a presynaptic modulatory effect is one of the functions for the alpha-bungarotoxin-sensitive nAChRs in the mammalian central nervous system.

Aortic input impedance during hypovolemic shock and after hyperosmotic solution infusion.

Aortic input impedance (Zin) was determined in 7 chloralose-urethane-anesthetized dogs. Flow and pressure were recorded in the ascending aorta during random cardiac pacing. These signals were processed on a spectrum analyzer utilizing the Fast Fourier Transform. Measurements were made 1) under control conditions; 2) every 5 min throughout 1 hr of hypovolemic shock; 3) every 5 min for 30 min after ending infusion of hyperosmotic solution (7.5% NaCl, 4.5 ml/kg body weight). We conclude that the determination of characteristic impedance (Zc) (average value of Zin from 4 to 10 Hz) can be useful for determining the initial phase of vascular decompensation in hypovolemic shock. After hyperosmotic solution infusion we observed a reduction in peripheral resistance, Zin, Zc, frequency of minimal Zin and frequency of phase crossover. These data strongly suggest a decrease in arterial vascular tonus.

Aortic input impedance during hypovolemic shock and after hyperosmotic solution infusion

Aortic input impedance (Zin) was determined in 7 chloralose-urethane-anesthetized dogs. Flow and pressure were recorded in the ascending aorta during randon cardiac pacing. These signals were processed on a spectrum analyzer utilization the Fast tansform. Measurements were made 1) under control conditions; 2) every 5 min throughout 1 h of hypovolemic shock; 3) every 5 min for 5 min for 30 min after ending infusions of hypersosmotic solution (7.5%) NaCl, 4.5 ml/Kg body weight). We conclude that the determination of characteristics impedance (Zc) (average value of Zin from 4 to 10 Hz) can be useful for determining the initial phase of vascular decompensation in hypovolemic shock. After hyperosmotic solution infusion we observed a reduction in peripheral resistance, Zin, Zc, frequency of minimal Zin and frequency of phase crossover. These datea strongly suggest a decrease in arterial vascular tonus