L.F. de Oliveira

Comparison between the effects of apomorphine and amphetamine on operant behavior.

Abstract Dose-effect relationships for apomorphine and amphetamine on lever-pressing behavior of rats, maintained by a 2 min fixed-interval schedule of water presentation, were determined. Lower doses of amphetamine increased responding particularly when control base-line rates were low, whereas higher doses decreased responding. In contrast, doses of apomorphine only decreased responding. Chronic reserpine treatment reduced the base-line response rate to approximately 15% of the mean control rate. Certain doses of amphetamine, but not apomorphine, partially antagonized the rate-depressant effect of reserpine. Since apomorphine stimulates central dopamine receptors, the present results suggest that dopaminergic mechanisms are not significantly involved in the mediation of the rate stimulant effects of amphetamine on operant behavior.

X-ray transmission microtomography using synchrotron radiation

This work reports the feasibility of a non-destructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) are given and microtomograms presented. Microtomograms of biomedical samples are presented. The tomography system was mounted into the XRF beamline that uses a high-intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 and 1 mm, respectively. The detector used to collect the data was a 512-pixel Hamamatsu linear array with width of 50 μm (36 μm of sensitivity length) and cooled by a Peltier junction, causing the temperature falling down to 15°C. The samples were placed over a computer controlled table with 0.5° angular resolution and turned around the center covering 360°. To reconstruct the sample a parallel beam filtered back-projection algorithm was used.

Blockade by bufotenidine of the serotonin- and narcotic-analgesics-induced contraction of dog intestine in vivo

Abstract Serotonin (5-hydroxytryptamine, 5-HT) seems to mediate the effects of morphine in the intestine. Tryptaminic blocking agents such as LSD-25 (lysergic acid diethylamide) and BOL (bromolysergic acid diethylamide), do not block the effects of 5-HT or the effects of morphine in the intestine. However, bufotenidine, a neural tryptaminic receptor blocking agent blocks the effects of both 5-HT and morphine on intestinal motility.

Synchrotron biomedical applications using X-ray diffraction tomography

This work reports the feasibility of a nondestructive synchrotron radiation X-ray diffraction imaging technique. The coherent scattering properties of different tissue (water, Lucite, nylon and polystyrene) and bone (hydroxyapatite) substitute materials were evaluated. Furthermore, diffraction patterns of some polycrystalline solids (lead, platinum, dysprosium and silicon) were studied due to industrial and environmental human exposure to these metals. The X-ray diffraction measurements were carried out at 11.101 keV and the diffracted beam was detected by a fast scintillation detector. The obtained diffraction patterns form the basis of a selective tomography technique. Preliminary images are presented. The results encourage us to examine further the application of the two-dimensional selective method to biomedical imaging.

Interactions of 5-Hydroxytryptamine and Narcotic Analgesics on Dog Intestine in vivo

The effects of intra-arterially (i.a.) injected morphine and dextromoramide on 5-hydroxytryptamine (5-HT)-induced contrac tion of the jejunum of dog were tested. Dextromoramide increased the intestina

Blockade by DMPP and Nicotine of 5-Hydroxytryptamine, and Narcotic-Analgesics Contractile Effect on Dog Intestine in vivo

Morphine has been shown to release 5-hydroxytryptamine (5-HT) from the intestinal wall of dogs. The 5-HT released is suspected to be the mediator of the contractile effect of the narcotic-analgesics i

Classification of individual flexibility: before and after a long-term stretching program

The evaluation of the stretching effects through mean values of the entire sample can hide different adaptations between groups with distinct characteristics of joint flexibility. This study aimed to employ artificial neural networks to classify subjects according to their flexibility level and to investigate the effects of a 10-week stretching training. The stretching group (SG, n = 9) performed stretching exercises for triceps surae muscles 4–5 times a week over 10 weeks. Maximum dorsiflexion angle (MDA) and peak passive torque (PPT) data at pre-intervention were used in a k-means (k = 3) algorithm to group participants as flexible, intermediate or stiff. A feed-forward artificial neural network (multilayer perceptron) was trained using the pre-intervention dataset with the k-means labeled groups and classified the post-intervention data generated after the stretching protocol. MDA of SG increased significantly (p = 0.015) from 24.72 ± 7.70 to 29.81 ± 6.95° whereas PPT showed no significant differences. Following intervention, two subjects from the SG shifted from the intermediate to the flexible group, whereas one stiff subject changed to the intermediate group. The control group presented a random pattern of group change. This approach can aid future analysis of different adaptations to stretching programs.

X-ray transmission microtomography facility at the National Synchrotron Light Laboratory

This work reports the feasibility of a nondestructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) were available and tomography preliminaries were evaluated. Microtomograms of biomedical samples are presented. The tomographic system was mounted into the XRF beamline that uses a high intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 mm and 1 mm, respectively. The detector used to collect the data was a 512-pixel EG&G Reticon linear array with width of 50 /spl mu/m (36 /spl mu/m of sensitivity length ) and cooled by a Peltier junction, causing the temperature falling down to 15/spl deg/C. The samples were placed over a computer controlled table with 0.5 degree angular resolution and turned around the center covering 360 degrees. To reconstruct the sample was used a parallel beam filtered backprojection algorithm.