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J A Lorente

Publications and source records attributed to J A Lorente.

At least 19 recordsLinked to original sources
PubMed2006

The role of ACTH in the pathogenesis of polycystic ovarian syndrome in rats: hormonal profiles and ovarian morphology.

Numerous hypotheses have been proposed about the pathogenesis of the polycystic ovarian syndrome (PCOS). However, hormonal control of persistent follicles has not been established. The objective of the present study was to compare the follicular structure and hormonal profiles of rats treated with the adrenocorticotrophic hormone (ACTH) with two experimental models of PCOS. ACTH-treated animals were compared with those exposed to continuous light, those treated with estradiol valerate, and with control (in proestrous and diestrous). Serum hormone levels, histomorphometrical changes, and immunoexpression of vimentin, cytokeratins, cadherins, and proliferating cell nuclear antigen (PCNA) were examined. Treatment with ACTH resulted in an elevation of corticosterone secretion with LH reduction but without changes in ovarian morphology. Although stress (or ACTH) stimulation may be only one of pathophysiological mechanisms involved in follicular cyst pathogenesis in other species, we do not have important evidence to suppose that this would happen in rats.

Adrenocorticotropic Hormone↗
PubMed2006

Oestradiol induced inhibition of neuroendocrine marker expression in Leydig cells of adult rats.

The objectives of this work were to determine the changes in the expression of neuroendocrine markers in Leydig cell by oestradiol treatment, and to determine whether testosterone is able to recover partially the effects of hormonal suppression induced by oestradiol. Adult male rats were injected daily with either 50 microg of oestradiol or oestradiol plus testosterone propionate (25 mg every 3 days) for 15 days. The animals were sacrificed and testicles were dissected and processed by routine histological protocols. FSH and LH serum levels were determined by radioimmunoassay. The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A (CrA), S-100 protein (S-100), P substance (PS), synaptofisin (SYN), neurofilament protein (NF), gliofibrillary acidic protein (GFAP) and neuron specific enolase (NSE) were used. The mean LH and FSH serum concentrations were consistently suppressed with hormonal treatments. Intermediate filaments (NF and GFAP) showed no difference in their expression. The expression of S-100, NSE and SYN was significantly lower in both hormone-treated groups. In oestradiol-treated rats, the immunoreactivity of CrA and SP decreased significantly but was restored after testosterone supplementation. Although the nature and functions of many of these substances in Leydig cells remain unknown, these results are consistent with the hypothesis that the expression of some neuroendocrine markers is hormonally controlled.

Animals↗
PubMed2004

Immunohistochemical study of intermediate filaments and neuroendocrine marker expression in leydig cells of laboratory rodents.

The aims of this study were to detect the expression of intermediate filaments and to verify the existence of marker substances for neuronal and neuroendocrine cells within the interstitial Leydig cells of laboratory rodent's testes, such as it has been described in other species. Adult male rats, mice, gerbils, Syrian hamsters and guinea-pigs were used and the localization of the different markers was achieved by the streptoavidin-peroxidase immunohistochemical method. The present study demonstrates in all rodents studied a similar pattern of localization in Leydig cells of intermediate filaments (vimentin, cytokeratin, neurofilament 200 kD and glial fibrillary acidic protein) and other marker substances (S-100, CgA, substance P and neurone-specific enolase), which are typical of neuroendocrine (APUD cells or paraneurones) and glial cells. The expression of these substances, related to neurotransmitters or neurohomones and other proteins characteristic of neuroendocrine cells, could suggest that it is a neural crest derived cell. Although this study provides more evidences about the immunoexpression of neuronal and glial markers in Leydig cells, this fact cannot be related directly to their embryological origin, because the current data support the hypothesis of a mesenchymal origin of the Leydig cells.

Animals↗
PubMed2004

Constant light exposure causes dissociation in gonadotrophin secretion and inhibits partially neuroendocrine differentiation of Leydig cells in adult rats.

The objective of this work was to study the changes that occur in the Leydig cells of rats exposed to continuous light. The laboratory rat is considered a non-photoperiodic species because exposure to short photoperiod has little or no effect on the reproductive status. However, exposure of adult female rats to constant light induces polycystic ovaries, indicating that extreme changes in the photoperiod affect the reproductive function seriously. Adult male rats were placed under continuous light conditions for a duration of 15 weeks. After this period, the animals were killed and testicles were dissected and processed by routine histologic protocols. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) serum levels were determined by radioimmunoassay (RIA). The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A, S-100 protein, P substance, synaptofisin, neurofilament protein-200, gliofibrillary acidic protein and neurone-specific enolase were used. The mean LH serum concentration was significantly lower, while the mean FSH level was significantly higher in treated animals. The expression of S-100, NSE, CrA, SP and SYN was significantly lower in treated animals. In conclusion, the constant light exposure acting directly at the pituitary level decreases LH secretion. The increased FSH secretion may be due to a partial reduction of the negative androgen feedback in the pituitary gland. Moreover, the constant light exposure affects the expression of some immunomarkers in Leydig cells, possibly because of the changes found in the gonadotrophin level and feedback mechanism.

Animals↗
PubMed2003

[Comparative study of the effect of complete prolonged neoadjuvant hormonal blockade versus standard hormonal blockade].

INTRODUCTION: Radical prostatectomy is considered as a curative treatment option in clinically localised prostate cancer patients. Therapy failure is related to positive surgical margins and/or extracapsular extension. The use of neoadjuvant combined androgen blockade (CAB) withdrawal therapy, mainly in cT2 disease, has been shown to decrease positive margin rates. However, CAB therapy remains controversial since there is no proof that this approach confers any benefit in relation to biochemical and clinical disease-free survival. Increasing negatives surgical margins and lower tumour volume (TV) with prolonged CAB therapy has been recently reported. AIM: To analyse the effect of 6 months neoadjuvant CAB therapy in front of 3 months in clinically localised prostate cancer patients submitted to radical prostatectomy. PATIENTS AND METHODS: The pathological stage and TV in forty-two patients treated by 6 months in front of thirty-four patients treated by 3 months were studied. The relationship of clinical stage and initial PSA concentration were analysed. RESULTS: TV was significantly lower in 6 months treated patients (0.97 cc vs. 0.48 cc, p = 0.05). The lowest TV was observed in cT1 patients, but significant differences only were observed in cT2 (1.5 cc vs. 0.86 cc, p = 0.04). No relationship between TV and PSA was obtained. No differences in the incidence of organ-confined disease were seen depending of the CAB length (47% vs. 43%, p = NS). However, increasing incidence of specimen-confined disease was observed in 6 months treated patients (56% vs. 74%, p = 0.05). CONCLUSION: The duration of neoadjuvant CAB can affect both TV and surgical margin status. Lower TV and increasing incidence of specimen-confined disease with 6 months CAB treatment were observed. Patients with palpable disease may be more benefited by this treatment option.

Androgen Antagonists↗
PubMed2003

A longer duration of neo-adjuvant combined androgen blockade prior to radical prostatectomy may lead to lower tumour volume of localised prostate cancer.

OBJECTIVES: To analyse tumour volume (TV) in clinically localised prostate cancer patients treated with neo-adjuvant combined androgen blockade (CAB) therapy prior to radical prostatectomy. PATIENTS AND METHODS: Two hundred consecutive patients treated between 1996 and 2000 were retrospectively analysed. Fifty patients underwent radical prostatectomy alone and 45 were treated with CAB for 1-3 months, 83 for 4-6 months and 22 for more than 6 months before surgery. Logistic regression analysis was performed to identify the strongest independent prognosticator of organ-confined disease. RESULTS: No evidence of residual cancer was found in 11 specimens (5.6%). Regarding TV, 20 specimens showed less than 0.1cc, 33 between 0.1 and 0.49cc and 86 more than 0.5cc. Smaller TV was found in CAB-treated patients. Significant correlation was observed between treatment duration and TV. In logistic regression analysis, only CAB duration and TV were significantly correlated with organ-confined disease. CONCLUSIONS: Prominent regressive features and lower TV were found after neo-adjuvant CAB. It seems that more prolonged treatment may lead to greater tumoural regression. Only tumour burden and length of CAB therapy were independent variables significantly correlated with pathologically localised prostate cancer.

Androgen Antagonists↗
PubMed2002

Social benefits of non-criminal genetic databases: missing persons and human remains identification.

A Missing Persons Genetic Identification Program (Phoenix Program) was implemented in Spain in order to try to identify cadavers and human remains that could not be identified using traditional forensic approaches; to our knowledge, this is the first database ever implemented and in function in the world. Two separate mitochondrial DNA (mtDNA) databases have been generated and comparisons can be made automatically to match identical or similar sequences contained in both databases. One database is called the Reference Database (RD), which contains mtDNA sequences from maternal relatives of missing persons that provide the samples voluntarily after informed consent. The other database is called the Questioned Database (QD) and is comprised of mtDNA data on unknown remains and cadavers that could not be unequivocally identified. The combined database is a civil database designed solely for human identification and because of the informed consent and voluntary donation of reference samples is different from other databases now used to solve criminal cases. It is timely and incumbent on other willing countries to begin an international collaboration so compatibility and full utility can be enjoyed with this kind of non-criminal database.

Cadaver↗
PubMed2001

Identification of missing persons: the Spanish "Phoenix" program.

In 1999, Spain was the first country to officially start a National Program to try to identify cadavers and human remains which could not be identified by the use of traditional forensic approaches. This attempt is called "Phoenix Program". Two independent mitochondrial DNA (mtDNA) databases were generated, which can automatically compare and match identical or similar sequences. One is the Reference Database, with mtDNA sequences from maternal relatives of missing persons, who provide the samples (buccal swabs) voluntarily; the other is the Questioned Database, comprised of mtDNA data of unknown remains and cadavers. Although the first phase of the program (typing of all unidentified human remains) will probably not be completed until December 2003, positive identifications are being made in the interim. To date, more than 1,200 families have contacted Phoenix, and at least 280 reference samples and 48 questioned evidences have been analyzed. When mtDNA matches are found, another independent analysis is performed as a part of the quality control mechanism. Once a match is confirmed (so far in 6 cases), an attempt is made to analyze short tandem repeat (STR) loci. We call for international collaboration to make this effort valuable worldwide.

Cadaver↗