Increased beat-to-beat variability of cerebral microcirculatory perfusion during atrial fibrillation: a near-infrared spectroscopy study.

AIMS: Atrial fibrillation (AFib) is associated with cognitive decline/dementia, independently from clinical strokes or transient ischaemic attacks (TIA). Recent in silico data suggested that AFib may induce transient critical haemodynamic events in the cerebral microcirculation. The aim of this study is to use non-invasive spatially resolved cerebral near-infrared spectroscopy (SRS-NIRS) to investigate in vivo beat-to-beat microcirculatory perfusion during AFib and after sinus rhythm (SR) restoration. METHODS AND RESULTS: Cerebral SRS-NIRS with high-frequency sampling (20 Hz) and non-invasive systemic haemodynamic monitoring were recorded before and after elective electrical cardioversion (ECV) for AFib or atrial flutter (AFL). To assess beat-to-beat effects of the rhythm status, the frequency distribution of inter-beat differences in tissue haemoglobin index (THI), a proxy of microcirculatory cerebral perfusion, was compared before and after SR restoration. Fifty-three AFib/AFL patients (mean age 69 ± 8 years, 79% males) were ultimately enrolled. Cardioversion was successful in restoring SR in 51 (96%) patients. In front of a non-significant decrease in arterial blood pressure extreme events between pre- and post-ECV measurements, a significant decrease of both hypoperfusive and hyperperfusive/hypertensive microcirculatory events was observed after SR restoration (P < 0.001 and P = 0.041, respectively). CONCLUSION: The present is the first in vivo demonstration that SR restoration by ECV significantly reduces the burden of extreme single-beat haemodynamic events in cerebral microcirculation. Future studies are needed to assess whether SR maintenance might slow long-term AFib-correlated cognitive decline/dementia.

Acute, post-ischemic sensorimotor deficits correlate positively with infarct size but fail to predict its occurrence and magnitude after middle cerebral artery occlusion in rats.

This study investigated whether sensorimotor deficits measured soon after reperfusion could predict the occurrence and magnitude of cerebral infarct following middle cerebral artery occlusion (MCAO). Rats were subjected to left MCAO for 2 h according to the intraluminal thread method. At 0, 1, 2, and 3 h after reperfusion, the animals were examined for neurological deficits using an expanded scale comprising the following tests: (A) postural reflex, (B) circling motion, (C) falling to contralateral side, (D) placement of the contralateral forelimb during motion, and (E) general state of alertness or consciousness. Deficits were graded from 0 (normal) to 2 or 3 (severe), and the final neuro-score was a summation of these scores over the various time points and among the various tests. The neuro-score of the animals that survived up to 24 h after MCAO ranged from 0 to 8.2 and positively correlated with infarct size (p=0.0002-0.001). However, at least three animals with moderate neuro-scores (4.5-6.0) did not exhibit any sign of infarcted brain tissue. Other animals having a distinct neuro-score (3.2 and 8.2, respectively) exhibited cerebral infarct with the same size (235 mm³). These data indicate that the extent of neurological deficit assessed within the first 3h after reperfusion does not reliably correspond to the occurrence and magnitude of cerebral infarct. Therefore, the neuro-score, when measured acutely within the first few hours after reperfusion, does not serve as a reliable criterion for preselecting animals with similar infarct size following transient MCAO.

Utilização de assentos de segurança por crianças matriculadas em creches / Child safety restraint use among children attending day care centers

OBJETIVO: Estimar a prevalência de utilização de assentos de segurança infantil e fatores associados. MÉTODOS: Estudo transversal observacional, com amostragem estratificada, realizado em 15 creches da cidade de Maringá, PR, entre os meses de março e maio de 2007. Cada creche foi visitada em apenas um dia letivo. O desfecho considerado foi a utilização de assento de segurança infantil por crianças de até quatro anos de idade. Carros (N=301) que transportavam crianças menores de quatro anos de idade foram abordados e as informações foram coletadas por meio de questionários semi-estruturados. Variáveis relacionadas a distribuição de adultos e crianças nos assentos do veículo, situação de restrição dos ocupantes e sexo do condutor foram analisadas. Para análise dos dados aplicou-se o teste exato de Fisher, qui-quadrado de Mantel-Haenszel e regressão logística. RESULTADOS: Entre os motoristas abordados, 51,8 por cento usavam cinto de segurança (60,4 por cento das mulheres, 44,9 por cento dos homens). Entre as crianças, 36,1 por cento usavam assentos de segurança infantil, 45,4 por cento eram transportadas soltas, 16,0 por cento estavam no colo de adultos, 2,7 por cento usavam o cinto de segurança. Segundo a regressão logística, os fatores que mais influenciaram o uso dos assentos de segurança infantil foram: idade da criança inferior a 15 meses (OR= 3,76), uso de cinto de segurança pelo condutor (OR= 2,45) e crianças pertencentes aos estratos sociocupacionais de maior renda e escolaridade (OR= 1,37). CONCLUSÕES: A utilização de assentos de segurança infantil mostrou-se associada à idade da criança, uso de cinto de segurança pelo condutor e estrato sociocupacional da creche. Frente ao baixo índice de utilização, o uso dos assentos de segurança infantil surge como desafio à medicina preventiva no Brasil, exigindo atenção e atuação para sua disseminação na população.

OBJECTIVE: To estimate the prevalence of child safety restraint use and factors associated. METHODS: Observational cross-sectional study using a stratified sampling conducted in the city of Maringá, Southern Brazil, between March and May 2007. Each day care center was visited at one day only. The outcome was use of child safety restraints by children under four. Vehicles (N=301) driving children under four were approached and information was collected using semi-structured questionnaires. Variables regarding child and adult seat distribution, use of safety restraints by occupants and driver's gender were analyzed. Data analyses included Fisher's exact test, Mantel-Haenszel chi-square test, and logistic regression. RESULTS: Of the drivers approached, 51.8 percent were using seat belts (60.4 percent among women, 44.9 percent among men). Among children, 36.1 percent were using child safety seats, 45.4 percent were unrestrained during traveling, 16.0 percent were seated on an adult lap, and 2.7 percent were using seat belts. The logistic regression showed the following factors affecting child safety restraint use: child age under 15 months (OR = 3.76); seat belt use by the driver (OR = 2.45); and children from socio-occupational condition with higher income and education (OR = 1.37). CONCLUSIONS: Child safety restraint use was associated to child age, seat belt use by the driver, and socio-occupational condition of day care centers. The finding of low rates of child safety restraint use poses a challenge to preventive medicine in Brazil, requiring attention and action to promote its widespread use.

Utilização de assentos de segurança por crianças matriculadas em creches / Child safety restraint use among children attending day care centers

OBJETIVO: Estimar a prevalência de utilização de assentos de segurança infantil e fatores associados. MÉTODOS: Estudo transversal observacional, com amostragem estratificada, realizado em 15 creches da cidade de Maringá, PR, entre os meses de março e maio de 2007. Cada creche foi visitada em apenas um dia letivo. O desfecho considerado foi a utilização de assento de segurança infantil por crianças de até quatro anos de idade. Carros (N=301) que transportavam crianças menores de quatro anos de idade foram abordados e as informações foram coletadas por meio de questionários semi-estruturados. Variáveis relacionadas a distribuição de adultos e crianças nos assentos do veículo, situação de restrição dos ocupantes e sexo do condutor foram analisadas. Para análise dos dados aplicou-se o teste exato de Fisher, qui-quadrado de Mantel-Haenszel e regressão logística. RESULTADOS: Entre os motoristas abordados, 51,8 por cento usavam cinto de segurança (60,4 por cento das mulheres, 44,9 por cento dos homens). Entre as crianças, 36,1 por cento usavam assentos de segurança infantil, 45,4 por cento eram transportadas soltas, 16,0 por cento estavam no colo de adultos, 2,7 por cento usavam o cinto de segurança. Segundo a regressão logística, os fatores que mais influenciaram o uso dos assentos de segurança infantil foram: idade da criança inferior a 15 meses (OR= 3,76), uso de cinto de segurança pelo condutor (OR= 2,45) e crianças pertencentes aos estratos sociocupacionais de maior renda e escolaridade (OR= 1,37). CONCLUSÕES: A utilização de assentos de segurança infantil mostrou-se associada à idade da criança, uso de cinto de segurança pelo condutor e estrato sociocupacional da creche. Frente ao baixo índice de utilização, o uso dos assentos de segurança infantil surge como desafio à medicina preventiva no Brasil, exigindo atenção e atuação para sua disseminação na população.(AU)

Child safety restraint use among children attending day care centers.

OBJECTIVE: To estimate the prevalence of child safety restraint use and factors associated. METHODS: Observational cross-sectional study using a stratified sampling conducted in the city of Maringá, Southern Brazil, between March and May 2007. Each day care center was visited at one day only. The outcome was use of child safety restraints by children under four. Vehicles (N=301) driving children under four were approached and information was collected using semi-structured questionnaires. Variables regarding child and adult seat distribution, use of safety restraints by occupants and driver's gender were analyzed. Data analyses included Fisher's exact test, Mantel-Haenszel chi-square test, and logistic regression. RESULTS: Of the drivers approached, 51.8% were using seat belts (60.4% among women, 44.9% among men). Among children, 36.1% were using child safety seats, 45.4% were unrestrained during traveling, 16.0% were seated on an adult lap, and 2.7% were using seat belts. The logistic regression showed the following factors affecting child safety restraint use: child age under 15 months (OR = 3.76); seat belt use by the driver (OR = 2.45); and children from socio-occupational condition with higher income and education (OR = 1.37). CONCLUSIONS: Child safety restraint use was associated to child age, seat belt use by the driver, and socio-occupational condition of day care centers. The finding of low rates of child safety restraint use poses a challenge to preventive medicine in Brazil, requiring attention and action to promote its widespread use.

Tacrolimus (FK506) reduces hippocampal damage but fails to prevent learning and memory deficits after transient, global cerebral ischemia in rats.

Transient, global cerebral ischemia (TGCI) leads to hippocampal damage and disruption of spatial learning and memory. The immunosuppressant, tacrolimus (FK506), prevents TGCI-induced hippocampal neurodegeneration, but its effectiveness in promoting the recovery of learning and memory performance after TGCI has been little investigated. Here, we use a confined version of the aversive, non-food rewarded radial maze to evaluate further the effects of FK506 on TGCI-induced learning and memory deficits. In the first experiment, rats were rendered ischemic (15 min 4-VO) and 20 days later were tested for acquisition of the radial maze task over 15 consecutive days (post-operative training). In the second experiment, naive rats were trained for 10 days and subjected to TGCI (pre-operative training); retention of task performance was assessed on days 31, 35 and 39 post-ischemia. Acquisition and retention performances were expressed as a) latency to find a goal box, b) number of reference memory errors, and c) number of working memory errors. Data are presented both across daily training sessions (15 days, 3-day blocks) and as a total value (summed over the 15 days). Histological examination was performed on the day after behavioral testing. In both experiments, FK506 (1.0 mg/kg) was given i.v. at the beginning of reperfusion, followed by doses applied intraperitoneally (i.p.) 6, 24, 48 and 72 h post-ischemia. TGCI markedly disrupted both acquisition and retention performance (p<0.0001-0.05). Treatment with FK506 did not prevent the TGCI-induced acquisition and retention deficits, independently of whether performances were quantified 'daily' or as a 'total' value. In contrast, FK506 reduced hippocampal damage significantly compared to the vehicle alone (p<0.001-0.05). We conclude that the present study did not confirm our earlier behavioral data, and suggest that FK506 is not effective in treating the behavioral outcomes of TGCI, despite its efficacy in reducing CA1, hippocampal damage. However, further studies including other behavioral tasks and more extensive neurohistological analysis, are needed to better elucidate the effectiveness of FK506 in promoting functional recovery in models of transient, global cerebral ischemia.