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J Carretero

Publications and source records attributed to J Carretero.

At least 37 records · Page 2Linked to original sources
PubMed1999

Growth-associated changes in glutathione content correlate with liver metastatic activity of B16 melanoma cells.

B16 melanoma (B16M) was used to study the relationship between glutathione (GSH) metabolism and the metastatic activity of malignant cells. GSH content increased in B16M cells during the initial period of exponential growth in vitro, to reach a maximum of 37 +/- 3 nmol/10(6) cells 12 h after plating, and then gradually decreased to control values (10 +/- 2 nmol/10(6) cells) when cultures approached confluency. On the contrary, glutathione disulphide (GSSG) levels (0.5 +/- 0.2 nmol/10(6) cells) and the rate of glutathione efflux (GSH + GSSG) (2.5 +/- 0.4 nmol/10(6) cells per h) remained constant as B16M grew. Changes in enzyme activities involved in GSH synthesis or the glutathione redox cycle did not explain shifts in the glutathione status (GSH/GSSG). However, two facts contributed to explain why GSH levels changed within B16M cells: a) high intracellular levels of GSH induced a feed-back inhibition of its own synthesis in B16M cells from cultures with low cellular density (LD cells); b) transport of cyst(e)ine, whose availability is the major rate-limiting step for GSH synthesis, was limited by cell-cell contact in cultures with high cellular density (HD cells). Intrasplenic injection of B16M cells with high GSH content (exponentially-growing cultures) showed higher metastatic activity in the liver than cells with low GSH content (cells at confluency). However, when low GSH-content cells (HD cells) were incubated in the presence of GSH ester, which rapidly enters the cell and delivers free GSH, their metastatic activity significantly increased. Our results demonstrate that changes in GSH content regulate the metastatic behaviour of B16M cells.

Animals↗
PubMed1998

Reduced nicotinamide adenine dinucleotide phosphate-diaphorase activity in the paraventricular nucleus of the rat hypothalamus is modulated by estradiol.

Based on previous studies demonstrating that reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (ND) activity is modulated by estradiol and the discovery of a new subtype of estrogen receptor highly expressed in the paraventricular nucleus of the hypothalamus (PVN), a possible estrogen influence on this activity was investigated in the neuronal populations (magno- and parvicellular) of this nucleus. Cryostat sections were cut and processed for the histochemical detection of the ND activity. Following ovariectomy (14 days), numerical data displayed a slight decrease in the number of ND-neurons, especially in the posterior magnocellular and the medial parvicellular subdivisions, which was reversed after daily treatment with estradiol benzoate. Administration of estradiol benzoate to male rats (14 days) induced a significant increase (P < 0.05) in the number of ND-neurons, mainly at the level of the posterior magnocellular subdivision. These data indicate that paraventricular ND-neurons are influenced by estradiol.

Animals↗
PubMed1998

Cell proliferation and apoptosis of thyroid follicular cells are involved in the involution of experimental non-tumoral hyperplastic goiter.

To assess the involvement of cellular inhibition and the appearance of apoptosis in regression of the hyperplastic thyroid gland towards normality, an experimental design was used to elicit non-toxic goiter by inducing hyperplastic goiter in rats by treatment with methimazole. We performed a morphological and PCNA immunocytochemical study together with in situ end labelling with bromodeoxyuridine in thyroid glands of rats receiving methimazole in their drinking water over 21 days after which they were allowed a recovery period of 0, 12, 24, 36, 48 and 72 h and 7, 14, 21 and 44 days. Serum T3 and T4 levels were found to be very low in the methimazole-treated animals although they increased after the goitrogenic compound had been withdrawn. Inhibition of cell proliferation and the burst of apoptosis play important roles in the regression of hyperplastic goiter in rats. Cell proliferation, which was strongly stimulated during goiter, fell significantly at 24 h, thereafter decreasing gradually as the recovery period progressed. Isolated cases of thyrocyte necrosis were observed ultrastructurally. Light and transmission electron microscopy revealed the existence of thyroid apoptosis with respect to the development of the study over time. Most apoptotic thyrocytes became detached from the follicular epithelium and later underwent cellular degeneration in the follicular lumen. The remaining apoptotic cells retracted their cytoplasm, lost contact with the follicular lumen and became located at the base of the follicles. The percentage of apoptosis showed that during the first week of thyroid involution apoptosis was already present but with low percentages while maximum values were attained at 21 days of survival. Our results suggest that, in the rat, during the return of thyroid follicular cells to normality after methimazole-induced hyperplastic goiter a balance arises between proliferation and cell death and that this balance is due to the inhibition of cellular proliferation and, secondarily, to the appearance of apoptosis, which becomes particularly evident towards the end of the first week after withdrawing the goitrogenic agent.

Animals↗
PubMed1998

Partial co-existence of NADPH-diaphorase and acetylcholinesterase in the hypothalamic magnocellular secretory nuclei of the rat.

Co-localization of NADPH-diaphorase (ND) and acetylcholinesterase (AChE) activities were explored in the magnocellular secretory nuclei of the rat hypothalamus by means of a double histochemical staining of the same sections. Partial co-existence was found in all the nuclei studied (paraventricular, supraoptic, fornicals and circular nuclei). No particular location of the neurons expressing both markers was found, although in the paraventricular nucleus all of them (ND +, AChE + and neurons expressing both markers) were preferentially located in the magnocellular subdivisions whereas in the parvicellular ones only some neurons belonging to all three types were detected, mainly located in the periventricular and medial subdivisions. The lowest degree of co-existence was found at the level of the main magnocellular nuclei (supraoptic and paraventricular) when compared with the accessory magnocellular nuclei, especially the posterior fornical and the circular nuclei. These results extend previous data on the chemical nature of the neurons producing nitric oxide in the neurosecretory nuclei and the possible functional role of this atypical messenger in the hypothalamus.

Acetylcholinesterase↗
PubMed1997

Decreases in the size and proliferation rate of VIP-immunoreactive cells induced in vitro by testosterone are associated with decreases in VIP release.

As in vitro study was carried out to determine whether testosterone directly inhibits the secretion of pituitary vasoactive intestinal peptide (VIP). A study was also conducted to elucidate the repercussions of treatment with 10(-6) M testosterone of monolayer cultures in the size and proliferation rate of pituitary VIP-immunoreactive cells, using double immunocytochemical labelling for proliferating cell nuclear antigen (PCNA) and VIP. Testosterone decreased the in vitro release of VIP from pituitary cells. It also decreased the percentage of pituitary VIP-immunoreactive and PCNA- and VIP-immunoreactive cells and decreased the size of the cellular and nuclear areas of these cells. Our results suggest that the inhibition of pituitary VIP secretion induced by testosterone could be exerted at pituitary level and that testosterone could act as a modulator of the proliferation rate of rat pituitary VIP-immunoreactive cells.

Animals↗
PubMed1997

Corticosterone induces hypoactivity of prolactin-immunoreactive cells.

In order to determine whether corticosterone regulates activity of rat lactotrophs by acting directly at the pituitary level, immunohistochemical studies were carried out in adrenalectomized rats, subjected or not to treatment with corticosterone or colchicine, and in monolayer cultures after incubation with corticosterone. Adrenalectomy increased cellular and nuclear areas (p<0.01) of prolactin-immunoreactive cells without affecting their cytoplasmic area. Similar results were found in adrenalectomized and colchicine-treated animals. Corticosterone reversed the effects of adrenalectomy, although normal values were partially reversed. In cultured pituitary cells, exposure to corticosterone reduced numerical density and cellular, cytoplasmic and nuclear areas with respect to control dishes. Morphological differences in shape, arrangement and nuclear features were observed after treatment with corticosterone. These results demonstrate an inhibitory effect of corticosterone on the activity of rat pituitary prolactin cells and suggest that corticosterone induces hypoactivity by acting on the pituitary prolactin cells of male rats.

Adrenalectomy↗
PubMed1997

In vitro effects of estradiol on pituitary GH-immunoreactive cells.

In order to determine whether estradiol modulates the proliferation and activity of somatotrophic cells in vitro, a study of GH-immunoreactive cells was carried out in pituitary monolayer cultures obtained from male adult rats treated with 10(-6)M estradiol for 3 hours. Cellular activity was evaluated in a morphometric study of GH-immunoreactive cells. The proliferation rate was determined by double immunostaining for GH and PCNA (proliferating cellular nuclear antigen). The results were compared to those obtained from control dishes. Estradiol was seen to increase the cellular (p < 0.05), nuclear (p < 0.01) and cytoplasmic areas (p < 0.05). Estradiol decreased the percentage of proliferating GH-immunoreactive cells (p < 0.05) and the nuclear density of somatotrophs (p < 0.05) when all cells present in the dishes were considered. However, when only GH-immunoreactive cells were considered, estradiol increased the proliferation rate of these cells (p < 0.05). Overall, our results suggest that, in vitro, estradiol stimulates the cellular activity and proliferation of GH-immunoreactive cells in the rat.

Animals↗
PubMed1996

NADPH-diaphorase activity and vasopressin in the paraventricular nucleus of the hypothalamus following adrenalectomy.

In order to investigate novel neuroendocrine functions of the nitric oxide synthesizing enzyme a combined histochemical and immunocytochemical study focused on the paraventricular nucleus of the hypothalamus was conducted to check a possible influence of bilateral adrenalectomy on three different neuronal populations, NADPH diaphorase (ND)-positive, vasopressin (VP)-immunoreactive and neurons expressing both markers. In the adrenalectomized animals, a slight increase (P > 0.05) of the number of ND magnocellular neurons was detected, whereas no changes were observed in the ND-parvicellular population and in the neurons showing coexistence (magno- and parvicellular) (P > 0.05). By contrast, following bilateral adrenalectomy, a significant increase (P < 0.05) in the VP-parvicellular population (anterior, medial and periventricular subdivisions) was detected, which was reversed when the animals received daily doses of corticosterone. These results suggest that nitric oxide is not closely related to the hypothalamic regulation of the adenocorticotropin secretion exerted by the paraventricular nucleus.

Adrenal Glands↗
PubMed1996

Dopamine inhibits in vitro release of VIP and proliferation of VIP-immunoreactive pituitary cells.

A double immunohistochemical study for VIP and proliferating cell nuclear antigen (PCNA) was carried out on monolayer cultures from adult male rats pituitary glands treated with dopamine (ranging from 10(-9) to 10(-5) M), in order to establish whether or not dopamine is involved in the regulation of the proliferation rate of pituitary VIP-immunoreactive cells. For all doses of dopamine assayed, the release of VIP to the culture medium, the numerical density of VIP-immunoreactive cells and the percentages of VIP- and PCNA-immunoreactive cells decreased significantly after dopamine treatment. These results suggest that dopamine could be a physiological inhibitor involved in the modulation of pituitary VIP proliferation rate.

Animals↗
PubMed1996

Morphometric evidence of the regulation of the activity of LH-immunoreactive cells by corticosterone. An in vivo and in vitro study.

The present study was performed to investigate the morphometric effects of the administration of corticosterone on LH-immunoreactive cells of pituitary monolayer cultures. In addition, the effect of bilateral adrenalectomy on the LH-adenohypophyseal cells was explored. In vitro administration of corticosterone induced a marked decrease in the morphometric parameters considered (cellular, cytoplasmic and nuclear areas). In vivo, bilateral adrenalectomy produced a significant increase in these parameters when compared to those obtained in normal and sham-operated animals. However, when the bilaterally adrenalectomized rats received a daily dose of corticosterone no significant changes in the morphometric parameters were found. Morphometrically, these combined in vivo-in vitro findings confirm a corticosterone-induced hypoactivity of LH-cells together with a direct effect of this glucocorticoid on LH-adenohypophyseal cells.

Adrenalectomy↗
PubMed1995

Effect of antihypertensive treatment on the increased beta 2-adrenoceptor density in patients with essential hypertension.

The effect of different antihypertensive drugs on the increased surface beta 2-adrenoceptor density in essential hypertension was evaluated to elucidate whether the possible effect of the treatment on these receptors was secondary to blood pressure decreases or a specific effect of the drugs. Thirty-nine untreated essential hypertensive patients and 28 normotensive control subjects were studied in basal conditions. Hypertensive patients were randomly assigned to three treatment groups: bisoprolol (10 mg/day, n = 15), enalapril (20 mg/day, n = 12), and verapamil SR (240 mg/day, n = 12), and were studied before and after 1 month of treatment. Plasma catecholamines were determined by a radioenzymatic assay. Surface beta 2-adrenoceptors were measured in intact lymphocytes by radioligand binding assay using the hydrophilic ligand [3H]-CGP12177. beta 2-adrenoceptor density was increased in hypertensive patients (P < .01). After treatment, mean blood pressure decreased similarly in the three groups, while plasma catecholamines showed no significant changes in any group. beta 2-adrenoceptor number decreased only in bisoprolol-treated patients (P < .05). Mean blood pressure decreases correlated with beta 2-adrenoceptor decrements only in bisoprolol-treated patients (r = 0.65, P < .05). beta 2-adrenoceptor density correlated with plasma epinephrine levels in the control group (r = -0.50, P < .01), but not in hypertensive patients before treatment. This correlation was also observed in hypertensive patients treated with bisoprolol (r = -0.52, P < .05), but not in those treated with verapamil or enalapril. Our results suggest that bisoprolol treatment reduces the increased surface beta 2-adrenoceptor density and restores its regulation by epinephrine in essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Adrenalectomy increases the glial fibrillary acidic immunoreactive-elements in the ventricular ependyma and adjacent neuropil of the rat third ventricle.

The reactions of bilateral adrenalectomy (14 days) on the rat glial fibrillary acidic-immunoreactive elements of the third ventricular ependyma and adjacent neuropil were analyzed using histological, immunohistochemical and morphometric methods. Bilateral adrenalectomy led to a drastic increase in the number of immunoreactive elements located in the neuropil adjacent to the third ventricle and the optic chiasm when compared to normal and sham-operated animals (p < 0.05). By contrast, the adrenalectomized animals receiving corticosterone showed the same characteristics and morphometric values as those found in normal and sham-operated animals. The results show that the participation of the adrenal gland in astroglial responses should be taken into account.

Adrenalectomy↗
PubMed1995

[Pleural empyema caused by Corynebacterium sp].

Until recently Corynebacterium sp. had been considered an infrequent cause of infection in humans. In the last few years, however, it has proven its ability to produce severe pulmonary and extrapulmonary infections, generally in immunodeficient hosts. We present a rare case of an immunocompetent man 68 years-old who developed community-acquired pneumonia and left pleural empyema, with Corynebacterium sp. isolated in pleural liquid. Response to thoracic drainage and antibiotic therapy (imipenem and clindamycin) was good.

Aged↗
PubMed1995

In vitro morphometric and proliferative variations in VIP-immunoreactive pituitary cells induced by estradiol.

Using double labelling for proliferating cell nuclear antigen (PCNA) and vasoactive intestinal peptide (VIP), a study was conducted to elucidate the repercussions of the addition of estradiol to monolayer pituitary cultures on the morphology, size, number, mitotic index and PCNA labelling index of VIP-immunoreactive cells, comparing the results with those obtained in control cultures. The addition of estradiol (100 nM) over 3 h of incubation led to a significant increase (p < 0.01) in the cellular, cytoplasmic and nuclear areas of VIP-immunoreactive cells and in the number of these cells. The same treatment elicited an even greater increase in the mitotic index (p < 0.01) and PCNA labelling index (p < 0.01) of VIP-immunoreactive cells. The results obtained suggest that estrogens induce proliferation and hyperplasia of in vitro VIP-immunoreactive pituitary cells.

Animals↗
PubMed1995

Dog neutrophil stimulation and cell surface expression of heat shock proteins induced by AHN 086.

The effect of AHN 086 [1-(2-isothiocyanatoethyl)-7-chloro-1,3-dihydro-5-(4- chloro-phenyl)-2H-1,4-benzodiazepine-2-one hydrochloride], an irreversible ligand of the mitochondrial benzodiazepine receptor, was studied in the heat shock protein (HSP) expression and the activation of dog neutrophils. At micromolar concentrations, AHN 086 induced a dose-dependent increase in free radical production (309 +/- 13% at 1 x 10(-5) M). This compound also increased the phagocytic activity (73 +/- 3.5% at 5 x 10(-6) M). Immunohistochemical results showed that AHN 086 induced the expression of HSP in neutrophil membranes. At 1 x 10(-5) M, the percentage of positive cells was: 90.2 (27 kD), 90.6 (72 kD) and 92.8 (90 kD). This expression was accompanied by a decrease in the presence of nuclear and cytoplasmic HSP. Flow cytometry studies showed that this cell membrane expression was located on the neutrophil surface and could be a consequence of HSP mobilization from nucleus and cytoplasm.

Animals↗
PubMed1995

Morphological findings of an interrelationship among the neurosecretory axons of the neural lobe of the hypophysis.

In order to establish whether osmotic stimuli induce variations in the contact regions among neurosecretory axons of the neural lobe of the hypophysis, adult Sprague-Dawley rats of both sexes were treated with furosemide, a diuretic drug. Contacts between adjacent membranes with no condensations of the axolemma but increase in their osmiophilia were observed. After treatment with furosemide interaxonal contacts were significantly increased (p < 0.01, in relation to control animals). Additionally, following treatment with furosemide, axo-axonic synapses among the axons of the neural lobe were found. These findings suggest the existence of interactions among activated neurosecretory axons of the neural lobe of the adult rat.

Animals↗
PubMed1995

In vitro modifications in the proliferation rate of prolactin cells are accompanied by nuclear morphometric variations.

In order to establish the correlation between in vitro proliferation rate and morphometric variations of prolactin immunoreactive cells, a morphometric study was carried out in rat pituitary monolayer cultures by means of the double immunocytochemical staining methods employing mouse monoclonal antiproliferative cell nuclear antigen (PCNA) and rabbit anti-prolactin (PRL) as primary antibodies. PCNA was found to be an adequate marker for proliferation in pituitary monolayer cultures. 48.35 +/- 2.78% of the cells present in the culture were in active cell cycle after 3 days of incubation and a similar proportion, 54.93 +/- 2.83% was found after 7 days. On the 3rd day, PRL immunopositive cells accounted for 15.16 +/- 0.21% of the total cellular content in the dishes and 8.68 +/- 0.12% of the PCNA immunoreactive cells were also PRL immunopositive cells and, 60.95 +/- 2.65% of PRL cells stained for PRL and PCNA. On the 7th day, an increase to 32.18 +/- 0.60% of PRL cells was found; the PCNA and PRL cells accounted for 60.32 +/- 2.34% of the total PRL cells, and 19.88 +/- 1.09% of the PCNA reactive cells stained for PRL. Additionally, the morphometric analysis performed after 3 or 7 days of incubation showed that, while the size of PRL cells remained unmodified, the nuclear area had increased on the 7th day in relation to the 3rd day (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗