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Biomedical subjects

M Cervantes

Publications and source records attributed to M Cervantes.

50 records · Page 3Linked to original sources
PubMed1975

Analysis of various factors involved in EEG synchronization during milk drinking in the cat.

Electroencephalographic (EEG) and multineuronal activity (MUA) from several brain structures were recorded in 11 adult cats during milk drinking. Milk drinking elicited parietal and hippocampal EEG synchronization and inhibited multiunit discharge in several brain regions. The proportion of EEG synchronization varied considerably between animals, but remained more or less constant for each cat after several testing days. Neither modification of milk concentration nor fasting influenced the proportions of EEG synchronization during milk drinking. Adaptation of the animals to the experimental environment facilitated the appearance of EEG synchronization during milk drinking. Chlorpromazine (3 mg/kg) significantly increased the proportion of EEG synchronization observed during milk drinking. By contrast, displacement of the head, neck or postural body adjustments during milk drinking blocked EEG synchronization. Amphetamine also had a suppressive effect on the EEG parietal and hippocampal synchronic activity observed during milk drinking. Our results suggest that development of parietal EEG synchronization in response to pleasant stimulation is a complex phenomenon requiring a relaxed condition of the animal, including its adaptation to the experimental environment and relative immobility with the concomitant diminution of afferent inflow from some of the muscles involved in locomotion.

Amphetamine↗
PubMedDate not supplied

Neuroprotective effect of melatonin on brain damage induced by acute global cerebral ischemia in cats.

BACKGROUND: Melatonin has been proposed as a neuroprotective agent on the basis of its ability to function as a free radical scavenger, provided that lipoperoxidation and other free radical damage induced by reactive oxygen species resulting from cerebral ischemia are relevant pathophysiologic processes of ischemic neuronal damage. METHODS: The effects of melatonin or vehicle on neurologic deficit scores (Todd scale; maximal deficit score = 100, daily during 7 days after the ischemic episode) and neuronal population of hippocampal CA1-CA4 fields (cresyl violet stain, at the eighth day after the ischemic episode) were evaluated in adult male cats subjected to a 15-min period of acute global cerebral ischemia induced by cardiorespiratory arrest, and in cats subjected to a sham procedure. Continuous intravenous (iv) administration of either melatonin 10 mg/kg/h in 10% ethanol in saline or the vehicle alone (3 mL/kg/h) for 6 h starting 30 min after the end of the period of global cerebral ischemia was used as treatment. RESULTS: Global cerebral ischemia resulted in a severe loss of neurons in hippocampal CA1-CA4 fields (9, 13, 30 and 28% remaining neurons, respectively) of ischemic vehicle-treated cats in comparison with sham cats (100%). By contrast, remaining neurons in these regions were between 81 and 100% in the ischemic melatonin-treated cats, values that are nonsignificantly different as compared with sham cats. Values of remaining neurons in CA1-CA4 fields in ischemic melatonin-treated cats were significantly higher than those in ischemic vehicle-treated cats. Neurologic deficit scores in ischemic vehicle-treated cats (42-77 at day 1, 6-39 at day 7) were significantly higher than those in ischemic melatonin-treated cats (16-38 at day 1, 0-6 at day 7) on the days after the ischemic episode. CONCLUSIONS: Overall, the results support the neuroprotective effect of melatonin against the neuronal cerebral damage induced by acute global cerebral ischemia.

Acute Disease↗
PubMedDate not supplied

[Histopathology of sun prurigo].

BACKGROUND: Solar or actinic prurigo (PS) is one of the most common skin diseases observed in our country, particularly in the pediatric age; in our institution it is on the 14 place with a frequency of 1.34%. It represents an abnormal reaction to solar light and in its pathogenesis diverse factors participate, mainly immunogenetical and environmental. Although their clinical characteristics are already specified, the histopathological features are still not well documented. MATERIAL AND METHODS: We carried out a retrospective and observational study in order to analyze the histopathologic changes in 20 samples of skin coming from 20 pediatric patients with PS; in all of them diagnosis was well established on clinical criteria. RESULTS: Twenty children with PS of more than one year of evolution, ten of each sex, all mestizos or indigenous inhabitants of Mexico City and vicinity; we identified recent and late lesions, with epidermal and dermal changes, the more conspicuous were: spongiotic papules usually with psoriasiform epidermal hyperplasia, in association with perivascular, superficial and mild lymphocytic infiltrates, usually with few eosinophils, exocytosis of lymphocytes into the epidermis, pigment incontinence and extravasation of erythrocytes. CONCLUSIONS: The PS is an inflammatory cutaneous disease for which histopathological diagnosis is feasible of being established on skin biopsies of recent or late lesions.

Adolescent↗
PubMedDate not supplied

Effects of nimodipine on multiunit activity of several brain structures following acute global cerebral ischemia-anoxia in cats.

The effects of nimodipine, a 1,4-dihydropyridine calcium channel blocker, on multiunit activity (MUA) of several brain structures were investigated in cats during 6 h immediately following acute global cerebral ischemia-anoxia induced by a 10 min cardiorespiratory arrest (CRA), as well as in cats exposed to sham procedures corresponding to CRA. Four groups of cats were studied: 1) CRA and continuous administration of nimodipine, 1 microgram/kg/min iv during 6 h; 2) CRA and continuous administration of vehicle; 3) sham and continuous administration of nimodipine as in group 1; 4) sham and vehicle as in group 2. MUA and electroencephalogram disappeared during ischemia-anoxia; their progressive recovery occurred throughout the hours following CRA, although 6 h after CRA MUA was still lower than its control prearrest values in all the recorded subcortical structures. Delta-like waves, isolated spikes, and bursts of fast EEG waves occurred during the recovery of EEG activity. Nimodipine inhibited the otherwise increasing MUA in mesencephalic reticular formation, hippocampus and putamen, but not in ventromedial hypothalamus, during the hours following acute global cerebral ischemia-anoxia. Absence of isolated spikes and bursts of fast EEG activity was noted in the EEG of CRA-, nimodipine-treated cats. Nimodipine significantly reduced MUA in hippocampus but not in other cerebral structures in cats of the sham treated group. The results suggest the involvement of 1,4 dihydropyridine sensitive calcium channels in the cellular mechanisms related to neuronal activity after cerebral ischemia-anoxia, and the possible relationship between the effects of nimodipine on MUA and better functional conditions of the central nervous system after acute global cerebral ischemia-anoxia.

Action Potentials↗
PubMedDate not supplied

Brain injury following cardiorespiratory arrest in cats. Effects of alphaxalone-alphadolone.

The effects of alphaxalone-alphadolone acetate (27.07 microM/kg-7.68 microM/kg) on neurologic injury following acute cerebral ischemia induced by an 8 min cardiorespiratory arrest (CRA) were investigated in cats through the analysis of neurological deficit scores and brain electrical activity; i.e., electroencephalogram (EEG) from parieto-occipital cortices and EEG and multiunit activity (MUA) from mesencephalic reticular formation (MRF). The CRA resulted from electrically induced cardiac arrest and stopping of mechanical ventilation in paralyzed cats which were successfully resuscitated within the immediate 4 min after the end of CRA. Two groups of cats were studied: I. Untreated, which received saline iv; II. Treated, which received alphaxalone-alphadolone acetate iv, 7-9 min after the end of CRA. Neuromuscular blockade and mechanical ventilation were maintained until 8 h following the CRA; then the cats were allowed to recover spontaneous respiratory activity. EEG phenomena were different in untreated and treated cats during this immediate post-arrest period. The former showed rhythmic bursts of fast (12-20 Hz) EEG activity at 1-2 sec intervals from 15-20 min until 3-4 h after the CRA, abundant spikes and delta-like waves. By contrast, administration of alphaxalone-alphadolone acetate resulted in burst suppression EEG pattern during 1 h. Progressive recovery of background EEG activity occurred afterwards. MUA from MRF disappeared during the CRA, however 6 h later the mean MUA frequency in untreated cats ranged between 32-46% and in treated cats 18-27% of their control mean frequencies during paradoxical sleep (100%). Daily electrographic records were performed in all the cats during quiet attentive behavior at each of the five days following the CRA. Significant differences were found in the frequency distributions of MUA from MRF (1st day, p less than 0.01; 5th day, p less than 0.01) as well as in the cortical EEG waves (1st day, p less than 0.01; 5th day, p less than 0.05) before and after the CRA in the untreated group. A wide dispersion of MUA values, and increased proportions of delta and theta-like waves and spindle bursts, besides a significantly high (p less than 0.001) number of spikes occurred in these EEG records the days following the CRA. The frequency distributions of MUA and EEG did not significantly differ before and after the CRA in the treated group; however, a significantly high (p less than 0.05) number of spikes was found in treated cats following the CRA.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Modifications of acoustic habituation by interruption of visual input in quipazine treated cats.

The influence of interruption of the visual input on acoustic habituation was studied in cats before and following the administration of quipazine, 3 mg/kg iv. The characteristics of acoustic habituation were analyzed through the magnitude and temporal course of multiunit activity (MUA) responses elicited in the mesencephalic reticular formation (MRF) by repetitive acoustic stimuli (70 db, 50 Hz trains of 2 sec duration) in 6 freely moving cats with cortical electrodes over the parietal cortex and bipolar electrodes chronically implanted in MRF and basolateral amygdala (AMN). The cats were submitted to repetitive acoustic stimulation during one 30 min period before, and three 30 min periods after drug administration in the following conditions: a) with unmasked eyes; b) with masked eyes by means of dark contact lenses. Persistent attentive behavior, catatonic attitudes, hypersynchronous (6 Hz, 100-150 microV) EEG activity and significant increase of spontaneous MUA in FRM and AMN were induced by quipazine both in the cats tested with unmasked and with masked eyes. This increase of MUA was higher immediately following drug administration and progressively decreased, although MUA values remained significantly higher than controls 110 min after quipazine administration. Acoustic habituation, evidenced through the progressive decrease of MUA responses of MRF to acoustic stimuli, was observed before quipazine administration when the cats were tested with unmasked and with masked eyes; as well as in cats tested with unmasked eyes following drug administration. However, the MUA responses to acoustic stimuli did not decrease in cats with masked eyes during acoustic stimulation periods 0-30 min and 40-70 min after quipazine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMedDate not supplied

Breast cancer cytogenetics: a review and proposal for clinical application.

Cytogenetic analyses of hematological neoplasms have proved to be relevant in the diagnosis, treatment, and prognosis of afflicted patients. Breast cancer (BC) cytogenetics is expected to contribute in the same fashion. Literature has shown that clone-specific chromosomal changes do occur in BC, yet, their clinical significance is unknown. Most of the studies have been conducted on patients with advanced stage tumor. Karyotypic analyses of the few reported cases from stage I BC tumors revealed a higher frequency of single clonal abnormalities. This work describes an ongoing BC cytogenic study on samples from stage I tumors to enhance and clarify this observation. Included as control are chromosomal analyses of peripheral blood and peritumoral normal tissue samples of these patients, which might provide information regarding predisposing cytogenetic aberrations. Non-random chromosomal abnormalities in BC include involvement of chromosomes 1, 3, 6, 11, 16, and 17. Three groups of non-random chromosomal alterations, ranging from specific abnormalities, partial monosomies, and secondary changes (eg, numerical loss of chromosomes) are described. Survival appears to be more favorable in patients without complex karyotypes. A better understanding of the clinical and etiologic implications of BC is expected to emerge from continued assessment of breast tumor cytogenetics.

Breast Neoplasms↗