Biomedical subjects

M I Nogueira

Publications and source records attributed to M I Nogueira.

8 recordsLinked to original sources

PubMed2000

Induced inflammatory process in Peripatus acacioi Marcus et Marcus (Onychophora).

The inflammatory response induced by the implant of a suture thread in Peripatus acacioi muscle was characterized under light and transmission electron microscopy (TEM). After 24 and 48 h granulocytes were observed migrating through the connective tissue toward the suture thread. These cells contain cytoplasmic eosinophilic granules as well as free granules near to the thread. There were few spherule cells with eccentric smooth kidney-shaped acidophilic nuclei and basophilic granules. Cells with intermediary characteristics as well as cells with a central basophilic nucleus with scarce acidophilic cytoplasm devoid of granules were also found. Under TEM, the granulocytic coelomocytes show small and homogeneous electron dense granules, while the spherule cells possess spherules that can be heterogeneous, granular, or with myelin figures. An acute induced inflammatory process is described for the first time in Onychophora and contributes to the scarce available literature on the function of the coelomocytes within this group.

Animals↗

PubMed2000

Afferent connections of the caudal raphe pallidus nucleus in rats: a study using the fluorescent retrograde tracers fluorogold and true-blue.

Afferent connections to the caudal region of the nucleus raphe pallidus (RPa) in rats were studied using fluorogold and true-blue as tracers. Due to its ability to produce limited injection sites, true-blue proved to be more appropriate than fluorogold for studying long distance connections in a narrow structure such as the RPa. Fluorescent, retrogradely-labeled perikarya were found in the preoptic area (median, medial and lateral nuclei), hypothalamus (anterior, dorsal, lateral and posterior areas, and the peri- and paraventricular nuclei), zona incerta, central gray (dorsal, ventral and ventro-lateral), reticular formation of the brainstem, trigeminal spinal nuclei and in the spinal cord (laminae V-X at thoracic, lumbar and sacral levels). This connection pattern suggests the involvement of the RPa in autonomic, somatic and endocrine functions.

Afferent Pathways↗

PubMed2000

Involvement of the caudal raphe nuclei in the feeding behavior of rats.

Involvement of the caudal raphe nuclei (raphe pallidus, RPa; raphe magnus, RMg, and raphe obscurus, ROb) in feeding behavior of adult rats was studied by measuring c-Fos protein expression, in animals submitted to the "meal-feeding" model of food restriction in which the rats were fed ad libitum only from 7:00 to 9:00 h, for 15 days. The experimental groups submitted to chronic fasting, named 'search for food' (SF), 'ingestion of food' (IF) and 'satiety of food' (SaF) were scheduled after a previous study in which the body weight and the general and feeding behaviors were evaluated by daily monitoring. Acute, 48-h fasting (AF) was used as control. In the chronic group, the animals presented a 16% reduction in body weight in the first week, followed by a continuous, slow rise in weight over the subsequent days. Entrainment of the sleep-wake cycle to the schedule of food presentation was also observed. The RPa was the most Fos immunopositive nucleus in the chronic fasting group, followed by the RMg. The ANOVA and Tukey test (P<0.05) confirmed these results. The IF group was significantly different from the other three groups, as also was the number of labeled cells in the RPa in SF and IF groups. Nevertheless, no significant difference was observed between RMg and RPa, or RMg and ROb in the SaF and AF. However, it is interesting to observe that the groups in which the animals were more active, searching for or ingesting food, presented a larger number of labeled cells. These results suggest a different involvement of the caudal raphe nuclei in the somatic and autonomic events of feeding behavior, corroborating the functions reported for them earlier.

Animals↗

PubMed1998

Expression of Fos protein in the rat central nervous system in response to noxious stimulation: effects of chronic inflammation of the superior cervical ganglion.

The aim of this study was to investigate the possible interactions between the nociceptive system, the sympathetic system and the inflammatory process. Thus, the superior cervical ganglion of rats was submitted to chronic inflammation and Fos expression was used as a marker for neuronal activity throughout central neurons following painful peripheral stimulation. The painful stimulus consisted of subcutaneously injected formalin applied to the supra-ocular region. Fos-positive neurons were identified by conventional immunohistochemical techniques, and analyzed from the obex through the cervical levels of the spinal cord. In the caudal sub-nucleus of the spinal trigeminal nuclear complex, the number of Fos-positive neurons was much higher in rats with inflammation of the superior cervical ganglion than in control rats, either sham-operated or with saline applied to the ganglion. There was a highly significant difference in the density of Fos-positive neurons between the inflamed and control groups. No significant difference was found between control groups. These results suggest that the inflammation of the superior cervical ganglion generated an increased responsiveness to painful stimuli, which may have been due to a diminished sympathetic influence upon the sensory peripheral innervation.

Animals↗

PubMed1997

A practical device for histological fixative procedures that limits formaldehyde deleterious effects in laboratory environments.

Formaldehyde vapor levels were evaluated in a histological fixative laboratory and environments where anatomical pieces treated with this fixative are stored or handled. Formaldehyde concentration in the air may reach values up to 9 times higher than that established (0.3 ppm) by the international official surveillance bureaus. These results emphasize the need to perform these activities in an environment with good exhaust conditions in view of the deleterious effects of formaldehyde. Therefore, we designed a practical modular mechanical device to carry out transcardiac fixative perfusion inside an exhaust hood. This device is coupled to accessories that help surgical procedures, animal head tissue cooling and collection of organic and chemical residues for posterior discharge or treatment. In addition, as it was designed to be readily assembled and disassembled it releases the hood for other tasks.

Air Pollutants↗

PubMed1991

Extraretinal modulation of accessory optic units in the pigeon.

1. Electrophysiological methods were used to investigate the pretectal and telencephalic control of units within the nucleus of the basal optic root (nBOR) of the accessory optic system of pigeons. 2. Electrical stimulation of the pretectal lentiform nucleus mainly produced excitatory effects on nBOR units with temporal-to-nasal directional preference (among 109 cells, 51% were excited, 23% were inhibited and 23% were not affected) and inhibitory effects on units with nasal-to-temporal preferences (among 88 cells, 43% were inhibited, 38% were not affected, and 19% were excited). 3. Electrical stimulation of the visual Wulst (considered to be the equivalent of the visual cortex) produced mainly inhibitory effects on units with downward preferences (among 123 units, 47% were inhibited, 24% were excited and 29% were not affected), and mixed effects on units with upward preferences (among 70 cells, 30% were excited, 36% were inhibited and 34% were not affected). 4. Excitatory effects of LM stimulation had first-spike latencies ranging from 2-20 ms (mean +/- SEM, 5.5 +/- 0.7 ms), whereas latencies of W stimulation ranged from 6 to 30 ms (13.0 +/- 0.9 ms). 5. These results provide additional information about the neural substrates of the optokinetic nystagmus.

Animals↗

PubMed1988

Telencephalic and pretectal modulation of the directional selectivity of accessory optic neurons in the pigeon.

Direction-selective units within the accessory optic system of the pigeon were shown to respond more strongly to motion along two main directions, downward-nasal and upward-temporal. Following ipsilateral telencephalic or pretectal lesions, these directions were modified in a systematic way. In the former, the principal response directions were downward-nasal and temporal and in the latter, downward-temporal and upward-temporal. These data indicate that the non-retinal afferents play an important role in the functional organization of the accessory optic system.

Animals↗

PubMed1988

A study of the brain barrier in the ventral nerve cord of the American cockroach treated with hexane-acetone and DDT.

The present study examines electrophysiological alterations in the blood brain barrier of the American cockroach when the solvent hexane-acetone is applied topically to the ventral nerve cord. Rupture of the barrier was evaluated by perfusion with saline in which NaCl was replaced with choline chloride at 28 degrees and 15 degrees C. The electrophysiological effects of an ethanol DDT suspension on the ventral nerve cord previously treated with hexane-acetone at 28 degrees C and 15 degrees C were consistent with the rupture of the blood brain barrier and the negative temperature coefficient of DDT toxicity.

Acetone↗