Study Of Acute Effects Research Articles

Mindfulness meditation and bimanual coordination control: study of acute effects and the mediating role of cognition.

Mindfulness meditation (MM) involves and benefits cognitive functioning, especially attention and inhibition processes, which are also implicated in the control of complex motor skills, such as bimanual coordination. Thus, MM practice could potentially enhance bimanual coordination control through its cognitive benefits. Accordingly, in this study, we investigated the acute effects of a brief MM session on bimanual coordination dynamics, attention, and inhibition abilities, as well as the mediation link between MM's cognitive and motor improvements. Healthy meditation-naïve (novices, n = 29) and meditation-experienced participants (meditators, n = 26) were randomly assigned to either an active control intervention (attentive listening to a documentary podcast) or a MM intervention (breathing and open monitoring exercise), both lasting 15 min. In the motor domain, pre- and post-tests assessed participants' ability to intentionally maintain the anti-phase coordination pattern at maximal movement frequency and resist the spontaneous transition to the in-phase pattern. In the cognitive domain, the participants' attentional, perceptual inhibition and motor inhibition abilities were assessed. Following both interventions, meditators and novices improved the stability of their anti-phase coordination pattern (p = 0.034, ηp2 = 0.10) and their attentional performance (p's < 0.001, ηp2 > 0.40). Only following the MM intervention, meditators and novices improved their ability to intentionally maintain the anti-phase pattern by delaying or even suppressing the spontaneous transition to in-phase (p's < 0.05, ηp2 ≥ 0.11), and improved concomitantly their motor inhibition scores (p = 0.011, ηp2 = 0.13). No effects were found on perceptual inhibition. The increase in motor inhibition capacities did not however statistically mediate the observed acute effects of MM on bimanual coordination control. We showed that a single MM session may have acute benefits in the motor domain regardless of the familiarity with MM practice. Although these benefits were concomitant to enhanced attentional and motor inhibition abilities, no formal mediation link could be established between the observed motor and cognitive benefits. This study paves the way for the investigation of the mechanisms underlying MM effects on motor control, as well as longer-term benefits.

Immunohistochemical Study of Acute Effects of Ethanol on Midbrain of Wistar Rats Associated with the Date of Birth of Neurons in Encephalon

La verificacion de los efectos agudos del etanol sobre el mesencefalo, cuyas neuronas se forman principalmente en la E14, puede ratificar si los efectos agudos del etanol estan asociados, en terminos de prevalencia, a la fecha de nacimiento de neuronas en ciertas regiones del cerebro. El objetivo de este estudio fue determinar los efectos de la exposicion aguda al etanol sobre la densidad neuronal del mesencefalo y asociar estos resultados con los efectos agudos de etanol en otras regiones del cerebro bajo las mismas condiciones. Las ratas fueron tratadas con etanol intraperitoneal durante un dia (E12) y 1h despues de la ultima inyeccion de etanol fue aplicado BrdU. Los animales fueron sacrificados, los cerebros fueron removidos y seccionados. Las secciones fueron tratados con DAB para la revelacion de BrdU, las secciones fueron tenidas con safranina para un grupo y otro grupo se tineron con H&E. Los efectos agudos de la inyeccion de etanol en E12 sobre el mesencefalo no fueron detectados en este estudio. Los datos de la literatura sugieren que los efectos deletereos del consumo agudo de etanol solo se producen si la droga se inyecta en etapas cercanas al comienzo de la migracion de las neuronas en esa region particular del cerebro.

Does Lipophilicity Per Se Induce Adjuvant Effects? Methyl Palmitate as Model Substance Does Not Affect Ovalbumin Sensitization

Anthopogenically introduced substances and pollutants are suspected to promote senstitization and development of allergic airway diseases, that is, acting as adjuvants. Lipophilicity may serve as an immunological warning signal, promoting adjuvant effects. Whether the lipophilicity of an inhaled compound induces immunomodulatory effects was investigated in a murine inhalation model with the highly lipophilic methyl palmitate (MP) as model substance. First, studies of acute effects following a 1-h exposure of up to 348 mg/m3 MP showed no effects on cell composition in bronchoalveolar lavage (BAL) or on lung function parameters. Thus, MP did not possess irritant or inflammatory properties, which may be a precursive stimulus for adjuvant effects. Second, mice were exposed to aerosols of MP, 6 or 323 mg/m3, for 1 h followed by a 20-min low-dose ovalbumin (OVA) inhalation. OVA only and OVA + Al(OH)3 served as control groups. Exposures were performed 5 times/wk for 2 wk followed by a weekly exposure for 10 wk. Finally, the mice were challenged with a high-dose OVA aerosol for 3 consecutive days. Neither OVA-specific immunoglobulin (Ig) G1, IgE, or IgG2a production, nor inflammatory cells in BAL, nor respiratory patterns were significantly affected in the MP groups. The OVA + Al(OH)3 group had a significantly higher IgG1 and IgE production, as well as higher eosinophil infiltration in the BAL fluid. These studies showed that effects of adjuvants not are necessarily due to their lipophilicity; that is, additional structural properties are required.

Measuring exposure for the epidemiologic study of acute effects.

This report explores the importance of characterizing short-term (peak) exposures for successful epidemiologic study of acute reversible effects. By selecting upper respiratory tract irritation, which is time-limited, reversible, and not critically affected by host factor sensitivities, the illustrated approach (directed at an acute respiratory irritant) provides insights on issues important in the general study of acute effects. The fundamental concern in a study of acute irritant effects is that such events occur in response to abrupt increases in exposure. This calls for a closer examination of how to distinguish bursts, or peaks, of exposure from continuous exposures measured simply as time weighted averages. Three parameters of peak exposures are discussed: duration, magnitude, and frequency. The importance of duration is illustrated by contrasting exposure patterns relevant for the study of acute vs. chronic health effects. The minimum magnitude of a peak relevant to the study of a specific physiologic response requires knowledge of the threshold below which no detectable response occurs. For any identified threshold level, only exposures exceeding that level are defined as relevant peaks for an exposure-response analysis. Finally, the issue of frequency, the minimum length of time between successive exposures necessary for the subject to return to baseline risk, is explored. A study of respiratory irritation associated with sodium borates is used to illustrate these issues.

Cyclophosphamide modulation of bronchoalveolar cellular populations and macrophage oxidative metabolism. Possible mechanisms of pulmonary pharmacotoxicity.

Cyclophosphamide, an immunosuppressive alkylating agent, has been reported to cause acute and chronic pulmonary injury in both humans and animals. Cyclophosphamide is also a common component of multi-drug regimens that show high pulmonary toxic potential. Although mechanisms of pulmonary damage caused by cyclophosphamide or other cytotoxic agents are unknown, possibilities include direct toxicity to pulmonary tissue or indirect toxicity through activation of pulmonary inflammatory cells. We report here a model system for the study of acute effects of cyclophosphamide on pulmonary immune cells in rats. Our findings show that 16 h after 1 intraperitoneal dose of cyclophosphamide there is: a dose dependent release of locally produced low molecular weight chemotactic factors for blood monocytes into bronchoalveolar lavage (BAL) fluid, a pulmonary influx of immature myeloperoxidase positive macrophages in low dose cyclophosphamide treated animals, an enhancement of oxidant generation by pulmonary macrophages from low dose treated animals that correlates with the presence of myeloperoxidase positive macrophages, the presence of factors in BAL fluid of treated rats that modulate oxidant release by normal rat pulmonary macrophages, a dose dependent reduction in the percentage of BAL lymphocytes, and evidence for pulmonary injury as manifested by elevated BAL fluid albumin concentrations in low dose cyclophosphamide treated animals. These findings suggest that cyclophosphamide may induce pulmonary injury through activation of pulmonary immunocompetent cells and subsequent attraction of systemic inflammatory cells.

Low dose bromocriptine: A study of acute effects in chronic medicated schizophrenics

1. 1. An acute low oral dose (2 mg) of bromocriptine was administered in a randomized double blind fashion to 11 chronic symptomatic medicated schizophrenic patients. 2. 2. There was an overall improvement for the group on the Brief Psychiatric Rating Scale (BPRS) following bromocriptine. 3. 3. Plasma homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, and vanilloyl-mandelic acid concentrations were unchanged after bromocriptine. 4. 4. Bromocriptine concentrations in the plasma showed a large inter-individual variation. 5. 5. There was a significant inverse correlation between plasma bromocriptine concentration and total BPRS score at 60 minutes post-bromocriptine administration. 6. 6. These results suggest a need for further replication in a larger study population and a need for controlled studies with chronic administration of low dose bromocriptine in chronic medicated schizophrenic patients.

The effect of intravenously administered almitrine, a peripheral chemoreceptor agonist, on patients with chronic air-flow obstruction.

Almitrine, a peripheral chemoreceptor agonist, was given intravenously in a dose of 0.5 mg/kg/h for 2 h in a randomized double-blind manner with placebo, to 11 patients with severe chronic air-flow obstruction and hypoxemia (SaO2 less than 90%). There was no significant placebo effect. Maximal respiratory effect occurred at the end of the almitrine infusion with an increase in ventilation from 8.2 + 0.9 to 11.6 + 1.5 L/min (mean +/- SEM), and improvements in SaO2 from 83 +/- 3 to 90 +/- 2%, in PaO2 from 48 +/- 2 to 55 +/- 3 mmHg, and in PaCO2 from 54 + 3 to 47 +/- 4 mmHg. Venous admixture was reduced from 38 +/- 4% to 22 +/- 3%. In 4 patients, blood gas values substantially improved, but there was no change in total ventilation for ventilatory pattern. This study of acute effects showed that almitrine improved arterial PO2 and PCO2 in patients with chronic air-flow obstruction both by increasing ventilation and by improving ventilation-perfusion relationships.