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Fernand Labrie

Publications and source records attributed to Fernand Labrie.

69 records · Page 4Linked to original sources
PubMed2003

Are women with Sjögren's syndrome androgen-deficient?

OBJECTIVE: We hypothesize that androgen deficiency is a critical etiologic factor in the pathogenesis of aqueous-deficient and evaporative dry eye in Sjögren's syndrome (SS). We investigated whether women with SS have a deficiency in total androgens. We also examined whether these patients have elevated serum concentrations of estrogens. METHODS: Blood was drawn from women with primary and secondary SS and age matched controls, and analyzed for steroid concentrations by gas and liquid chromatography-mass spectrometry. RESULTS: Our results show that women with SS are androgen-deficient. Concentrations of 5-androstene-3beta,17beta-diol (5-diol), dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), androsterone-glucuronide (ADT-G), and androstane-3a,17beta-diol-G (3alpha-diol-G) were all significantly reduced in SS sera relative to controls. In contrast, SS was not associated with significant alterations in the serum concentrations of testosterone, androstenedione, estrone, or 17beta-estradiol. These overall findings could not be attributed to the use of oral contraceptives or hormone replacement therapy, because the concentrations of 5-diol, DHEA, DHT, ADT-G and 3a-diol-G were also decreased in patients with SS compared to levels in control women who were not taking exogenous estrogens. CONCLUSION: Our results show that women with SS are androgen-deficient.

Androgens↗
PubMed2003

[Future prospects for primary hormone therapy in localized and locally advanced prostate cancer].

The authors consider current and future prospects for primary hormone therapy in localized and locally advanced prostate cancer by comparing this form of treatment (hormone monotherapy) with neoadjuvant radiation therapy and radical prostatectomy. Neoadjuvant hormone therapy prior to radiation therapy has been proven effective in recent years, and currently the United States is showing a year-by-year increase in the use of androgen blocking agents during the early stage of prostate cancer. A survey of recent research findings, clearly showed that, for patients with localized prostate cancer, there is no significant difference in survival rate between hormone monotherapy and radical prostatectomy. In the future we can expect to see an increase in available treatment options for localized and locally advanced prostate cancer, with the optimal therapy for each individual patient to be selected by the attending physician in discussion with the patient.

Androgen Antagonists↗
PubMed2002

Androgen blockade in prostate cancer in 2002: major benefits on survival in localized disease.

The last 20 years have witnessed major advances in the field of prostate cancer, both in terms of diagnosis and treatment. Using screening with PSA, 99% of prostate cancers can now be diagnosed at a clinically localized or potentially curable stage. Over a 11-year period starting in 1988, the Québec screening study performed among 45,000 men aged 45-80 years has shown that the prostate cancer death incidence has decreased by 64% in men who had screening. The impact of screening, however, requires early application of the most efficacious treatments. In this context, the most important recent therapeutic advance in the field of prostate cancer is androgen blockade, namely medical castration with LHRH agonists, the availability of pure antiandrogens and combined androgen blockade (CAB) using medical or surgical castration in association with a pure antiandrogen. In the six studies performed in localized or locally advanced disease, the improved cancer-specific survival ranges between 37 and 81% at 5 years of follow-up for patients who received androgen blockade. On the other hand, data already available show that long term and continuous (not intermittent) androgen blockade is highly efficient and can achieve long term control or possible cure of localized prostate cancer.

Aged↗
PubMed2002

Comparison of the effects of EM-652 (SCH57068), tamoxifen, toremifene, droloxifene, idoxifene, GW-5638 and raloxifene on the growth of human ZR-75-1 breast tumors in nude mice.

EM-652 exerts pure antiestrogenic activity in the mammary gland and endometrium, while tamoxifen, the antiestrogen most widely used for the treatment of breast cancer, exerts mixed antiestrogenic-estrogenic activity in these tissues. Our objective was to compare the agonistic and antagonistic effects of EM-652 with tamoxifen and 5 other antiestrogens on the growth of ZR-75-1 human breast xenografts in ovariectomized nude mice. During the 23 weeks of treatment at a daily oral dose of 50 microg, EM-652 was the only compound that decreased tumor size relative to pretreatment values, whereas the 6 other antiestrogens only decreased to various extents the progression rate stimulated by estrone. Under estrone stimulation, all groups of animals had more than 60% of their tumors in the progression category except for the EM-652-treated group, where only 7% of the tumors progressed. In the absence of estrone stimulation, progression was seen in 60%, 33%, 21% and 12% of tumors in the tamoxifen-, idoxifene-, toremifene- and raloxifene-treated groups, respectively, while only 4% of tumors progressed in the EM-652-treated group. The agonistic and antagonistic actions of each antiestrogen were also measured on endometrial epithelial cell thickness. Our present findings indicate that EM-652, in addition to being the most potent antiestrogen on human breast tumor growth, has no agonistic effect in breast and endometrial tissues. Since previous data have shown benefits of EM-652 on bone density and lipid profile, this compound could be an ideal candidate for chemoprevention of breast and uterine cancers, while protecting against osteoporosis and cardiovascular disease.

Animals↗
PubMed2002

Effects of the new generation selective estrogen receptor modulator EM-652 and oral administration of estradiol valerate on circulating, brain, and adrenal beta-endorphin and allopregnanolone levels in intact fertile and ovariectomized rats.

OBJECTIVE: To investigate the effects of oral estradiol valerate (EV); EM-652, a new-generation selective estrogen receptor modulator; and both agents on central and peripheral beta-endorphin (beta-EP) and allopregnanolone levels in fertile and ovariectomized rats. DESIGN: Prospective study. SETTING: Animal laboratory in an academic research environment. ANIMALS: Thirteen groups of eight Wistar female rats received oral EV (0.01 or 0.05 mg/kg of body weight daily), EM-652 (0.1, 1, or 5 mg/kg daily), or EV (0.05 mg/kg daily) and EM-652 (0.1, 1, or 5 mg/kg/daily) for 14 days. INTERVENTION(S): beta-Endorphin levels content in the hypothalamus, hippocampus, anterior and neurointermediate pituitary, and plasma were measured. Allopregnanolone levels in the hypothalamus, hippocampus, anterior pituitary, adrenal glands, and serum were measured. MAIN OUTCOME MEASURE(S): beta-Endorphin and allopregnanolone levels. RESULT(S): In ovariectomized rats, administration of EV or EM-652 reverses changes in beta-EP and allopregnanolone levels induced by ovariectomy. Administration of EM-652 plus EV prevents the increase in beta-EP and allopregnanolone levels induced by EV in the hippocampus, hypothalamus, and pituitary but not in the adrenal glands and serum. CONCLUSIONS: In ovariectomized rats, EM-652 has an estrogen-like action that becomes antiestrogenic in the presence of EV administration. In fertile animals, EM-652 exerts estrogen-like or slight antiestrogenic effects.

Administration, Oral↗
PubMed2002

Can combined androgen blockade provide long-term control or possible cure of localized prostate cancer?

OBJECTIVES: To investigate the possibility that more complete blockade of androgens or combined androgen blockade (CAB) could lead to even longer term control of localized prostate cancer. A series of recent studies have shown important benefits on survival using medical or surgical castration in localized or locally advanced prostate cancer. METHODS: The effect of CAB on long-term control or possible cure of prostate cancer was evaluated by the absence of biochemical failure or prostate-specific antigen (PSA) rise for at least 5 years after cessation of continuous treatment. A total of 57 patients with localized or locally advanced disease received CAB for periods ranging from 1 to 11 years. Twenty patients with Stage B2/T2 prostate cancer who were treated for a median duration of 7.2 years (range 2.8 to 11.7) with CAB stopped treatment and were followed up for a median of 4.9 years. Eleven patients with Stage B2/T2 also received CAB but for only 1 year. Twenty-six patients with Stage C/T3 treated with continuous CAB for a median of 9.9 years (range 3.8 to 11.3) with undetectable PSA levels stopped treatment and were followed up for a median of 5.6 years. The median follow-up since diagnosis was 14.6 years for patients with Stage B2/T2 and 16.4 years for patients with Stage C/T3 disease. RESULTS: With a minimum of 5 years of follow-up after cessation of long-term CAB, two PSA rises occurred among 20 patients with Stage T2-T3 cancer who stopped treatment after continuous CAB for more than 6.5 years, for a nonfailure rate of 90%. For the 11 patients who had received CAB for 3.5 to 6.5 years, the nonfailure rate was only 36%. The serum PSA increased within 1 year in all 11 patients with Stage B2/T2 treated with CAB for only 1 year, thus indicating that active cancer remained present after short-term androgen blockade despite undetectable PSA levels. In all patients who had biochemical failure after stopping CAB, the serum PSA level rapidly decreased again to undetectable levels when CAB was restarted and remained at such low levels afterward. Of these patients, only 1 patient had died of prostate cancer at last follow-up. CONCLUSIONS: The present data suggest that long-term and continuous CAB offers the possibility of long-term control or possible cure of localized prostate cancer.

Androgen Antagonists↗
PubMed2002

Pharmacokinetics of oral dehydroepiandrosterone (DHEA) in the ovariectomised cynomolgus monkey.

Humans and primates are unique in having adrenals that secrete large amounts of DHEA and DHEA-S in the circulation. These steroids act as precursors of active androgens and estrogen's in a long series of peripheral target intracrine tissues. The marked decline of serum DHEA and DHEA-S concentrations with age in men and women has been incriminated in the development of various pathologies. This study provides detailed information on the effect of a single 50mg oral dose of DHEA on circulating estrogen's as well as androgens and their metabolites over 10h in adult ovariectomised (OVX) Cynomolgus monkeys. Serum DHEA, DHEA-S, testosterone (Testo) and androstenedione (4-dione) concentrations increased rapidly with a maximal value at approximately 1h after DHEA administration followed by a 60-80% decrease during the next 2-6h. An important sulfatation of DHEA occurs through first hepatic pass, thus, leading to a marked increase in serum DHEA-S. Serum androst-5-ene-3beta,17beta-diol and androsterone glucuronide (ADT-G) levels remained elevated on a plateau for 6h. Androstan-3alpha,17beta-diol-glucuronide, estradiol and estrone levels remained unchanged. The present data indicate the predominant transformation of the adrenal precursor DHEA into active androgens in peripheral tissues and support the importance of measurement of circulating glucuronide derivatives as index of peripheral or intracrine androgen formation and action.

Administration, Oral↗
PubMed2002

Genomic and nongenomic mechanisms of nitric oxide synthesis induction in human endothelial cells by a fourth-generation selective estrogen receptor modulator.

Cardiovascular disease is the leading cause of morbidity and mortality in postmenopausal women. EM-652 (acolbifene) is a fourth-generation selective ER modulator (SERM) exerting complete antiestrogenic effects on the breast and uterus. EM-652 potently inhibits bone resorption and induces positive lipid modifications in estrogen-deficient animals. As most of the cardioprotective actions of estrogen are exerted directly at the vascular level, we studied the effects of EM-652 on endothelial production of nitric oxide (NO) in vitro and in vivo. EM-652 triggers NO release by human umbilical vein endothelial cells through nongenomic mechanisms, rapidly activating endothelial nitric oxide synthase (eNOS) via an ER-dependent sequential activation of MAPKs and PI3K/Akt pathways independently from gene transcription or protein synthesis. Moreover, EM-652 increases eNOS protein levels during prolonged treatments. Upon pharmacological comparison, EM-652 is markedly more potent than the SERMs raloxifene and tamoxifen in increasing NO synthesis from endothelial cells. In ovariectomized and fertile rats, EM-652 increases aortic eNOS expression and enzymatic activity at low, but not at higher, dosages. The present data show that EM-652 (acolbifene) has estrogen-like activity on the vascular wall, directly increasing NO production through genomic and nongenomic mechanisms in vitro and in vivo.

Animals↗
PubMed2002

Perspective: prostate cancer susceptibility genes.

In many developed countries, prostate cancer is the most frequently diagnosed malignancy in men. The extent to which the marked racial/ethnic difference in its incidence rate is attributable to screening methods, environmental, hormonal, and/or genetic factors remains unknown. A positive family history is among the strongest epidemiological risk factors for prostate cancer. It is now well recognized that association of candidate genetic markers to this multifactorial malignancy is more difficult than the identification of susceptibility genes for some common cancers such as breast, ovary, and colon cancer. Several reasons may explain such a difficulty: 1) prostate cancer is diagnosed at a late age, thus often making it impossible to obtain DNA samples from living affected men for more than one generation; 2) the presence within high-risk pedigrees of phenocopies, associated with the lack of distinguishing features between hereditary and sporadic forms; and 3) the genetic heterogeneity of this complex disease along with the accompanying difficulty of developing appropriate statistical transmission models taking into account simultaneously multiple susceptibility genes, frequently showing moderate or low penetrance. Despite the localization of seven susceptibility loci, there has been limited confirmatory evidence of linkage for currently known candidate genes. Nonetheless, the discovery of the first prostate cancer susceptibility gene characterized by positional cloning, ELAC2 was achieved taking advantage of the Utah Family Resource. Moreover, common missense mutations in the ELAC2 gene were found to be significantly associated with an increased risk of diagnosis of prostate cancer in some studies. More recently, recombination map-ping and candidate gene analysis were used to map several genes, including the 2'-5'-oligoadenylate-dependent ribonuclease L (RNASEL) gene, to the critical region of HPC1. Two deleterious mutations in RNASEL segregate independently with the disease in two of the eight HPC1-linked families. Additional studies using larger cohorts are needed to fully evaluate the role of these two susceptibility genes in prostate cancer risk. Although a number of rare highly penetrant loci contribute to the Mendelian inheritance of prostate cancer, some of the familial risks may be due to shared environment and more specifically to common low-penetrance genetic variants. In this regard, it is not surprising that analyses of genes encoding key proteins involved in androgen biosynthesis and action, led to the observation of a significant association between a susceptibility to prostate cancer and common genetic variants, such as those found in 5alpha-reductase type 2 and AR genes.

Alleles↗
PubMed2001

Expression, crystallization and preliminary X-ray analysis of human and rabbit 20alpha-hydroxysteroid dehydrogenases in complex with NADP(H) and various steroid substrates.

Progesterone plays an essential role in the maintenance of the pregnancy of most mammals. 20alpha-Hydroxysteroid dehydrogenase (20alpha-HSD) catalyses the inactivation of progesterone into its inactive form, 20alpha-hydroxyprogesterone, and could thus be involved in progesterone withdrawal and in the control of gestation. In this report, the purification and crystallization of recombinant human and rabbit 20alpha-HSDs (h20alpha-HSD and rb20alpha-HSD) are described, two highly homologous enzymes possessing, in addition to their common 20alpha-HSD activity, different activities and substrate specificities. Complete diffraction data sets have been collected for crystals of rb20alpha-HSD in complex with NADP(H) and with either dihydrotestosterone (1.8 A), progesterone (1.7 A) or 4-androstenedione (1.8 A). All these crystals belong to the monoclinic space group P2(1). A partial data set has also been collected for a crystal of h20alpha-HSD (P2(1)2(1)2(1)) in complex with NADP(H) and progesterone.

20-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

Current status of endocrine therapy in localized prostate cancer: cure has become a strong possibility.

It is clear that all available means should be taken to diagnose prostate cancer early and to use efficient therapy immediately in order to prevent prostate cancer from migrating to the bones where treatment becomes extremely difficult and cure or even long-term control of the disease is an exception. The only means of preventing prostate cancer from migrating to the bones and becoming incurable is efficient treatment at the localized stage of the disease. In fact, since radical prostatectomy, radiotherapy and brachytherapy can achieve cure in about 50% of cases, these approaches are all equally valid choices as first treatment of localized prostate cancer. However, in view of the current knowledge and available data, nowadays, androgen blockade should also be considered as first line treatment. While showing the high efficacy of hormonal therapy in localized prostate cancer, present knowledge clearly indicate that long-term treatment with the best available hormonal drugs, somewhat similar to the 5 years of Tamoxifen in breast cancer, is required for optimal control of prostate cancer. It is also clear from the data analyzed that combined androgen blockage alone could well be an efficient therapy of localized prostate cancer while it has already been recognized as the best therapy for metastatic disease. This paper presents and discusses the current knowledge available on the use and results of endocrine therapy in localized prostate cancer.

Androgen Antagonists↗