PubMed Health⌕ Search

Biomedical subjects

G Fernández

Publications and source records attributed to G Fernández.

13 recordsLinked to original sources
PubMed1992

Regulation of somatostatin and growth hormone-releasing factor by gonadal steroids in fetal rat hypothalamic cells in culture.

The mechanism underlying the sexually dimorphic pattern of growth hormone (GH) secretion in the rat has not been clearly elucidated. In the present study, we assayed the possible direct effect of gonadal steroids on both somatostatin (SS) and growth hormone-releasing factor (GRF) in fetal rat hypothalamic cells in culture. Hypothalamic cells, obtained by mechanical dispersion, were maintained as monolayer cultures in serum-supplemented medium. After 20 days in culture, cells were incubated with serum free medium containing testosterone (T, 10, 20, 40 ng/dl) or estradiol (E, 0.1, 1, 10 ng/dl) for 48 h. At the end of the experiments, immunoreactive SS (IR-SS) and immunoreactive GRF (IR-GRF) were measured by specific radioimmunoassays (RIAs) in media and cell extracts. After 48 h of incubation with testosterone, somatostatin in both media and cells was significantly reduced. On the contrary, this treatment lead to a dose-dependent increase in media and cell GRF content. When cells were incubated with estradiol for 48 h, a significant inhibition in medium SS release was observed, whereas intracellular SS slightly increased at the highest concentration of 10 ng/dl. Estradiol treatment resulted in an inconsistent decrease in media and cells IR-GRF. Our results indicate that both SS and GRF are under the influence of testosterone and estradiol acting at the hypothalamic level, and furthermore suggest that at this stage of brain development, gonadal steroids may regulate GH secretion through their ability to modulate hypothalamic SS and GRF.

Animals↗
PubMed1992

Thyroid hormones regulate release and content of vasoactive intestinal peptide in cultured fetal cerebral cortical cells.

The effects of thyroid hormones (TH) on brain immunoreactive-vasoactive intestinal peptide (IR-VIP) secretion and content in cultured fetal rat cortical cells were studied. Cerebral cortical cells were maintained as monolayer cultures for 14-18 days. T3 or T4 (10(-7) M) caused a time-dependent decrease in total IR-VIP. Significant suppression was observed following treatment periods of 6 h or longer (24 and 48 h). Depending on the length of time cells had been deprived of TH prior to the addition of exogenous T3 or T4, these two thyroid hormones had different effects on IR-VIP accumulation. Both T3 and T4 caused a dose-dependent suppression or IR-VIP accumulation when there was no deprivation period or when it lasted 4 h. However, a biphasic effect was observed when cells were deprived of TH for 17 and 24 h: low doses of T3 or T4 (from 10(-12) to 10(-10) M) significantly increased (p less than 0.05) total IR-VIP, while high T3 or T4 doses (10(-8) and 10(-7) M) caused a significant decrease (p less than 0.01). The TH action was furthermore shown to be reversible. After T3 (10(-7) M) removal and subsequent incubation in serum-free medium for 6, 24 and 48 h, T3-treated and control cells exhibited similar levels of IR-VIP release and content. At this time, a new exposure to T3 (10(-7) M) again had a suppressive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

In vivo and in vitro evidence of growth hormone-releasing factor-like produced locally in the adenohypophyseal cells of the rat.

In order to characterize immunocytochemically the existence of GRF in the rat adenohypophysis and the origin of this hormone, an immunocytochemical and morphometric study was made of r-GRF-immunoreactive cells from the adenohypophysis of untreated adult rats, adult rats treated intraventricularly with colchicine and in primary cultures of adult rat adenohypophyseal cells that had been incubated with serum devoid of GRF. r-GRF immunoreactive cells were observed in untreated rat pituitaries, both male and female, although the numbers of positive cells were greater in the males (p less than 0.05) and were found to increase in number following treatment with colchicine (p less than 0.01). These cells appeared dispersed throughout the anterior lobe, without forming clusters, and were often close to blood vessels. Additionally, immunoreactive cells appeared in the cultures at 7 days of incubation. The presence of GRF-immunoreactive cells in the adenohypophysis of rats previously treated with colchicine suggests the existence of a non-hypothalamic origin for r-GRF; this is confirmed by the findings obtained in the in vitro studies which would corroborate the hypothesis that the origin of the neuropeptide is in the rat adenohypophysis itself.

Animals↗
PubMed1991

Onychomycosis treated with itraconazole or griseofulvin alone with and without a topical antimycotic or keratolytic agent.

An open, comparative, randomized study was conducted using griseofulvin or itraconazole for the treatment of onychomycosis of the foot. Group I (45 patients) received itraconazole and Group II (45 patients) received griseofulvin. Each group was divided into three subgroups that received different topical treatment: antimycotic cream (isoconazole 1%), keratolytic cream (urea 40%), or placebo cream. The itraconazole group showed complete clearance in combination with isoconazole cream in 73.3% (11 of 15 patients), in combination with keratolytic cream in 78.5% (11 of 14 patients), and in combination with placebo cream in 91.6% (11 of 12 patients). The griseofulvin group showed complete clearance in combination with isoconazol cream in 46.1% (7 of 15 patients), in combination with keratolytic cream in 42.8% (6 of 15 patients), and in combination with placebo cream in 26.6% (4 of 15 patients). The itraconazole group showed better results compared with the griseofulvin group when the chi-square statistical method was used.

Administration, Topical↗
PubMed1991

Influence of hypothyroidism duration on developmental changes in the hypothalamic factors implicated in growth hormone secretion in the male rat.

The effects of hypothyroidism duration on several factors implicated in GH secretion control were studied in the male rat at different maturity stages, ranging from the peripuberal period to adulthood. Thyroid ablation was performed on 22-day-old Wistar male rats maintained on a low iodine diet (T group). Age-paired controls (C group) were fed with the same diet, supplemented with potassium iodide. Subgroups of T and C animals (aged 32, 42, 52, 82 and 112 days) were studied 10, 20, 30, 60 and 90 days after surgery. After pentobarbital anesthesia, jugular blood was withdrawn before and 5 min after an intravenous TRH stimulus, for GH assay. Hypothalamic and pituitary tissues were obtained in order to measure GH, immunoreactive somatostatin (IR-SRIF) and growth hormone-releasing factor (IR-GRF). Growth rate and serum testosterone confirmed that C rats reached sexual maturity by day 30 of the study. Mean +/- SE serum GH (ng/ml) increased (p less than 0.05) in C animals from day 10 (38.5 +/- 5) to day 30 (67.4 +/- 7.3), with no significant variations thereafter. The same time sequence pattern was observed in pituitary GH concentrations. In T rats, both serum and pituitary GH decreased progressively from day 10 to 90, being significantly lower than in C at all times of the study. No GH response to TRH could be found in C groups. In contrast, GH increased significantly (p less than 0.05) in T animals after TRH at days 20 and 30.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

Visual, auditory and somatosensory evoked responses in patients with cerebrovascular disorders.

A diagnostic evoked response battery, consisting of visual evoked responses to flashes and to a checkerboard pattern, auditory evoked responses to three different tones and somatosensory evoked responses to left, right and bilateral median nerve stimulation, was administered to 20 patients with strokes, and compared with 20 normal control subjects. Recordings were obtained at C3, C4, O1, O2, T3 and T4. Evoked responses were found to be of lower amplitudes and lower amplitudes and lower waveform symmetry (expressed by low correlation coefficients between left and right homologous areas) in the patients than in normal subjects. A discriminant equation with 17 variates was computed to separate the two groups. One patient (5%) and 2 (10%) normal subjects were misclassified. Comparison between patients with left or right lesions showed that somatosensory and auditory evoked responses were very useful for identification of the affected side. Quantitative study of evoked responses to different types of stimuli and sensory modalities provides a sensitive method for the evaluation of brain function in such patients. This technique gives higher accuracy than the routine EEG examination in terms of both the percentage of dectection and the accuracy of localization of the affected side.

Acoustic Stimulation↗
PubMedDate not supplied

[Visual somatosensory and auditory evoked potentials in multiple sclerosis].

In a group of 15 patients with multiple sclerosis and in a control group of 20 healthy subjects visual evoked potentials produced with flashes or checkerboard pattern, auditory evoked potentials after stimulation with three different tones, and somatosensory evoked potentials after stimulation of the left, right or both median nerves, and reactions to stroboscopic stimulation at seven different frequencies were investigated. Recording was done with unipolar leads from frontal, central, occipital and temporal regions on the left and right side. In patients with multiple sclerosis the cortical responses to all these stimuli had lower amplitude than in healthy subjects, and the reponses to stroboscopic stimulation were also abnormal in the group of patients. Different clinical signs related to various defects of sensory functions showed a high correlation with electrophysiological anomalies. Non-linear discrimination analysis was carried out using 13 variants (the amplitudes were calculated from peak to peak and correlation coefficients were calculated between identical regions on the left and right side) comparing the group of patients with the control group. Using this method it was possible to establish the correct diagnosis in all cases of multiple sclerosis and 85% of healthy subjects could have been included into the asymptomatic group. Since the methods used in these investigations are easy and can be easily automated the authors think that they could be very useful in the clinical diagnosis of multiple sclerosis.

Acoustic Stimulation↗
PubMedDate not supplied

[Early mechanical respiration with prolonged inspiration in the treatment of acute respiratory insufficiency in the newborn].

The experience at the Servicio de Medicina Perinatal Pediátrica of the Centro Hospitalario "20 de Noviembre" of the ISSSTE is reported on the application of a ventilatory assistance criterion to treat the severe respiratory distress syndrome in the newborn. Early application of intermittent mechanical ventilation (IMV) is established to avoid clinical impairment. The mechanical ventilator is used in such a way that without withdrawing therapeutic effectiveness, it may cut down to a minimum complications derived from the use of IMV. The results show increase in survivorship, specially among the lower weight population and less complications than with the previous management method, in spite of a 70% increase in the use of IMV.

Age Factors↗