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Electrophysical agents (EPAs) are core therapeutic interventions in academic physical therapy curricula around the world. They are used concomitantly with several other therapeutic interventions such as exercise, manual therapy techniques, medications, and surgery for the management of a wide variety of soft tissue disorders. Over the past decade, the practice of EPAs has been the subject of intense scrutiny in the U.S. This has been colored by some physical therapists publicly engaging in bashing rhetoric that has yet to be officially and publicly addressed by the guiding organizations which, together, regulate the practice of physical therapy in this country. Published in world renowned public media are unsubstantiated mocking remarks against the practice of EPAs and unethical allegations against its stakeholders. This rhetoric suggests that EPA interventions are "magical" treatments and that those practitioners who include them in their plans of care may be committing fraud. Such bashing rhetoric is in striking contradiction to the APTA's Guide to Physical Therapist Practice 4.0, which lists EPAs as one of its categories of interventions, the CAPTE's program accreditation policy, and the FSBPT's national licensing exam. The purpose of this commentary is to expose the extent of this discourse and to call to action the APTA, CAPTE, and FSBPT organizations, as well as physical therapists, with the aim at putting an end to this rhetoric.
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Glucuronidation, catalyzed by UDP-glucuronosyltransferase UGT2B enzymes, is a major inactivating and elimination pathway for androgen hormones in humans. Whether Ugt2b enzymes from mice are also reactive with these hormones have never been investigated. The present study aimed at evaluating the capability of murine tissues and Ugt2b enzymes to glucuronidated androgens. The 7 murine Ugt2b (Ugt2b1, 2b5, 2b34, 2b35, 2b36, 2b37 and 2b38) enzymes were cloned and stably expressed into HEK293 cells. In vitro glucuronidation assays were performed with microsomal proteins or homogenates from mice tissues (liver, kidney, intestine, adipose, testis, prostate, epididymis, bulbo, seminal vesicle, mammary glands, uterus, and ovary) and from Ugt2b-HEK293 cells. Male and female livers, as well as male kidneys, are the major sites for androgen glucuronidation in mice. The male liver is highly efficient at glucuronidation of dihydrotestosterone (DHT) and testosterone and is enriched in Ugt2b1 and 2b5 enzymes. Androsterone and 3α-Diol are conjugated in the male kidney through an Ugt2b37-dependent process. Interestingly, castration partially abolished hepatic Ugt2b1 expression and activity, while Ugt2b37 was totally repressed. DHT injection partially corrected these changes. In conclusion, these observations revealed the substrate- and tissue-specific manner in which murine Ugt2b enzymes conjugate androgens. They also evidence how androgens modulate their own glucuronide conjugation in mice.
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This paper provides a systematic, multidimensional demographic analysis of the degree to which negative economic consequences of population aging can be mitigated by changes in migration and labor-force participation. Using a microsimulation population projection model accounting for 13 individual characteristics including education and immigration-related variables, we built scenarios of future changes in labor-force participation, migration volumes, and their educational composition and speed of integration for the 28 European Union (EU) member states. We study the consequences in terms of the conventional age-dependency ratio, the labor-force dependency ratio, and the productivity-weighted labor-force dependency ratio using education as a proxy of productivity, which accounts for the fact that not all individuals are equality productive in society. The results show that in terms of the more sophisticated ratios, population aging looks less daunting than when only considering age structure. In terms of policy options, lifting labor-force participation among the general population as in Sweden, and education-selective migration if accompanied by high integration, could even improve economic dependency. On the other hand, high immigration volumes combined with both low education and integration leads to increasing economic dependency. This shows the high stakes involved with integration outcomes under high migration volumes.
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Envejecimiento/fisiología , Eficiencia , Emigración e Inmigración , Dinámica Poblacional , Empleo , Europa (Continente) , HumanosRESUMEN
OBJECTIVE: The aim of the study was to determine the range of serum sex-related steroids in normal postmenopausal women and in women of the same age with a diagnosis of vulvovaginal atrophy (VVA). METHODS: Validated mass spectrometry-based assays coupled to gas or liquid chromatography were used over a 10-year period for steroid measurements. Serum samples were obtained in up to 1,512 women aged 55 to 65 years. RESULTS: Serum estrone sulfate (E1S) and androsterone glucuronide (ADT-G), the main metabolites of estrogens and androgens, respectively, were 16.9% (Pâ=â0.005) and 16.1% (Pâ=â0.001) higher in women not diagnosed with moderate/severe VVA than those diagnosed with VVA. Serum estrone (E1) was 14.5% (Pâ<â0.0001) higher in women with no diagnosis of VVA, whereas the other steroids did not show meaningful differences. The limited biological significance of serum estradiol (E2) and testosterone is supported by the lack of statistical significance in the serum concentrations of these two steroids between the two groups. Most importantly, for the women without a diagnosis of VVA, the normal upper limit (95 centile) of serum E2 was 9.15 pg/mL (nâ=â364) and 10.7 pg/mL (nâ=â67) for a weighted average of 9.99 pg E2/mL. A limit of 10 pg E2/mL has recently been found by two other laboratories. When comparing 50- to 59-year-old and 70- to 79-year-old women, serum E2, E1S, ADT-G, and DHEA were, respectively, 24.4%, 22.6%, 27.0%, and 85.9% higher in the younger group. CONCLUSIONS: Somewhat higher values, namely, 16.9% and 16.1%, are observed in the serum concentrations of the estrogen (E1S) and androgen (ADT-G) metabolites in normal compared with women with a diagnosis of VVA. Such data indicating a lower estrogenic and androgenic global exposure in women diagnosed with VVA offers an opportunity for the local intravaginal administration of DHEA to replace the deficiency in endogenous DHEA.
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Androsterona/análogos & derivados , Atrofia , Estrona/análogos & derivados , Posmenopausia/sangre , Enfermedades Vaginales/sangre , Anciano , Androsterona/sangre , Estudios de Casos y Controles , Ensayos Clínicos como Asunto , Sulfato de Deshidroepiandrosterona/sangre , Estrona/sangre , Femenino , Humanos , Espectrometría de Masas , Persona de Mediana Edad , Testosterona/sangreRESUMEN
The objective is to review how the cell-specific amounts of intracellular androgens are all made in women from circulating dehydroepiandrosterone (DHEA) in each peripheral tissue, independently from the rest of the body. Following 500 million years of evolution, approximately three dozen cell-specific intracrine enzymes have been engineered in human peripheral tissues whereby the inactive sex steroid precursor DHEA mainly of adrenal origin is transformed into the appropriate minute intracellular amounts of androgens. These intracellular androgens are inactivated in the same cells, with no biologically significant release of active androgens in the circulation. The best estimate is that approximately 50% as much androgens are synthesized in women, compared to men of the same age. The problem with DHEA, however, the exclusive source of androgens in women of all ages, is that DHEA secretion has already decreased by an average of 60% at time of menopause and continues to decrease thereafter. The human-specific and highly sophisticated mechanisms of intracrinology permit each cell to control androgen availability according to its own needs independently from the remaining of the body. Such a mechanism is completely different from classical endocrinology well understood in men where testosterone of testicular origin is transported through the blood and has indiscriminate access to the androgen receptor (AR) in all AR-containing cells of the body. In men, both the endocrine and intracrine mechanisms are in operation while, in women, only the intracrine mechanisms responsible for intracellular formation from DHEA provide androgens.
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Andrógenos/química , Deshidroepiandrosterona/química , Esteroides/química , Andrógenos/sangre , Animales , Atrofia , Deshidroepiandrosterona/sangre , Estrógenos/sangre , Estrógenos/química , Femenino , Hormonas Esteroides Gonadales/sangre , Hormonas Esteroides Gonadales/química , Humanos , Masculino , Menopausia , Receptores Androgénicos/metabolismo , Esteroides/sangre , Testosterona/sangre , Enfermedades Vaginales/metabolismo , Enfermedades de la Vulva/metabolismoRESUMEN
OBJECTIVE: To illustrate the marked differences between classical endocrinology that distributes hormones to all tissues of the body through the bloodstream and the science of intracrinology, whereby each cell of each peripheral tissue makes a small and appropriate amount of estrogens and androgens from the inactive precursor dehydroepiandrosterone (DHEA), DHEA being mainly of adrenal origin. Because only the inactivated sex steroids are released in the blood, influence in the other tissues is avoided. METHODS: Molecular biology has been used for the identification/characterization of the steroid-forming and steroid-inactivating enzymes, whereas steroids have been measured by mass spectrometry-based assays validated according to the US Food and Drug Administration guidelines. RESULTS: Evolution over 500 million years has engineered the expression of about 30 steroid-forming enzymes specific for each peripheral tissue. These tissue-specific enzymes transform DHEA into the appropriate small amounts of estrogens and androgens for a strictly intracellular and local action. Humans, contrary to species below primates, also possess intracellular steroid-inactivating enzymes, especially glucuronyl transferases and sulfotransferases, which inactivate the estrogens and androgens at their local site of formation, thus preventing the release of a biologically significant amount of estradiol (E2) and testosterone in the circulation. Since DHEA becomes the unique source of sex steroids after menopause, serum E2 and testosterone are thus maintained at low biologically inactive concentrations with no activity outside the cells of origin. DHEA secretion, unfortunately, starts decreasing at about the age of 30 at various rates in different women. Moreover, there is no feedback mechanism to increase DHEA secretion when the concentration of serum DHEA decreases. Considering this mechanism is unique to the human, it seems logical to replace DHEA locally in women suffering from vulvovaginal atrophy (genitourinary syndrome of menopause). The clinical data obtained using a small dose of intravaginal DHEA (prasterone) confirm the mechanisms of intracrinology mentioned above which avoid biologically significant changes in serum E2 and testosterone. CONCLUSIONS: The symptoms and signs of vulvovaginal atrophy (genitourinary syndrome of menopause) can be successfully treated by the intravaginal administration of DHEA without safety concerns. This strategy exclusively replaces in the vagina the missing cell-specific intracellular estrogens and androgens. This approach avoids systemic exposure and the potential risks of estrogen exposure for the tissues other than the vagina.
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Deshidroepiandrosterona/administración & dosificación , Deshidroepiandrosterona/metabolismo , Posmenopausia/fisiología , Andrógenos/metabolismo , Atrofia/tratamiento farmacológico , Inhibidores Enzimáticos , Enzimas/metabolismo , Estrógenos/metabolismo , Femenino , Humanos , Espacio Intracelular/química , Espacio Intracelular/enzimología , Vagina/efectos de los fármacos , Vagina/patologíaAsunto(s)
Cromatografía Liquida , Estrógenos/sangre , Espectrometría de Masas en Tándem , Cromatografía Liquida/métodos , Cromatografía Liquida/normas , Femenino , Humanos , Menopausia/sangre , Estándares de Referencia , Espectrometría de Masas en Tándem/métodos , Espectrometría de Masas en Tándem/normas , Estados Unidos , United States Food and Drug Administration , Estudios de Validación como AsuntoRESUMEN
In the prostate, approximately 50% of androgens are from adrenal steroids, mainly dehydroepiandrosterone (DHEA), its sulfate and androstenedione. These compounds are converted first into testosterone, and then into the active hormone dihydrotestosterone (DHT). After having activated the androgen receptor (AR), DHT is reduced into androstane-3α-DIOL (3α-DIOL) and androsterone (ADT), which are subsequently converted into 2 inactive and easily excretable metabolites: 3α-DIOL-17glucuronide (3α-DIOL-17G) and ADT-3glucuronide (ADT-3G). The formation of these last derivatives through the glucuronidation reaction involves 2 UDP-glucuronosyltransferase (UGT) enzymes, namely UGT2B15 and UGT2B17. The present review article aims at providing a comprehensive view of the physiological and pharmacological importance of these 2 enzymes for the control of androgen homeostasis. We will resume: (i) how UGT2B15 and UGT2B17 contribute to androgen elimination; (ii) how their glucuronidation capacity influences the androgen signaling pathway in prostate cells; (iii) how they contribute to the anti-proliferative properties of AR antagonists in prostate cancer cells; and (iv) how AR and its spliced variants regulate the UGT2B15 and/or UGT2B17 genes expression. Finally, whether the unexploited AR-UGT axis could serve as a prognostic maker or a pharmacological target for novel therapeutics in the treatment of prostate cancer is also discussed. This article is part of a special issue entitled 'Essential role of DHEA'.
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Andrógenos/metabolismo , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Glucuronosiltransferasa/metabolismo , Neoplasias de la Próstata/enzimología , Línea Celular Tumoral , Proliferación Celular , Regulación de la Expresión Génica , Glucuronosiltransferasa/genética , Humanos , Masculino , Antígenos de Histocompatibilidad Menor , Pronóstico , Próstata/enzimología , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/patología , Receptores Androgénicos/metabolismoRESUMEN
Population aging is the population issue of the XXI century and many indices are used to measure its level and pace. In Science (2010), Sanderson and Scherbov suggested improvements to the measure of elderly dependency ratio. They identified several limitations to the use of chronological age as the main variable and proposed a new index, the Adult Disability Dependency Ratio, defined as the number of adults at least 20 years old with disabilities divided by the number of similarly aged adults without disabilities. They used the Sullivan prevalence-based method by multiplying derived disability rates to macro population projections. They showed results for several ECE and OECD countries; results for Canada (see online annex, available at https://www.sciencemag.org/content/329/5997/1287/suppl/DC1) were derived using coefficients of Italy. However, disability is a complex multidimensional process (see Carrière, Keefe, Légaré, Lin, & Rowe, 2007; Légaré and Décarie, 2011), and microsimulation can take into account its implied complexity. Our results for Canada, presented here, exceed those in Science to show how more-sophisticated projections of disabled older adults can improve the analysis. We used LifePaths, a Statistics Canada's microsimulation model, to provide a perspective of the phenomena unobtainable with prevalence-based methods.
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Simulación por Computador , Personas con Discapacidad/estadística & datos numéricos , Dinámica Poblacional/tendencias , Adulto , Anciano , Anciano de 80 o más Años , Canadá , Predicción , Humanos , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Adulto JovenRESUMEN
Androgen deprivation therapy (ADTh) remains a mainstay of prostate cancer treatment, but its efficacy is bypassed by mechanisms that are not fully understood. In human prostate cancer cells, androgen glucuronidation, catalyzed by the two UDP-glucuronosyltransferase (UGT) enzymes UGT2B15 and UGT2B17, is the major androgen inactivation pathway. In this study, we investigated the effect of ADTh on androgen glucuronidation to evaluate its potential clinical utility for prostate cancer prognosis or therapy. UGT2B15 and UGT2B17 expression was evaluated in prostate cancer specimens from untreated or treated patients and in cell models of prostate cancer exposed to clinically relevant antiandrogens. UGT2B15 and UGT2B17 protein levels in prostate were increased after 5 months of ADTh when compared with specimens from untreated patients. UGT2B15 expression remained elevated for up to 12 months, but UGT2B17 returned to initial levels as soon as after 6 months. Several androgen receptor (AR) antagonists tested caused a dose- and time-dependent stimulation of UGT2B15 and UGT2B17 expression and androgen glucuronidation in prostate cancer cell lines. The role of AR in these regulatory events was confirmed using AR-deficient LNCaP cells, in which UGT2B attenuation reduced the antiproliferative effects of AR pharmacologic antagonists. Through this combination of clinical and functional investigations, our work revealed that ADTh stimulates a local androgen metabolism in prostate cells, establishing a foundation to evaluate the potential of UGT2B15 and UGT2B17 as drug targets and/or molecular markers for ADTh responsiveness and maintenance in prostate cancer.
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Antagonistas de Andrógenos/uso terapéutico , Andrógenos/metabolismo , Antineoplásicos Hormonales/uso terapéutico , Glucuronosiltransferasa/metabolismo , Terapia Molecular Dirigida/métodos , Neoplasias de la Próstata/tratamiento farmacológico , Antagonistas de Andrógenos/farmacología , Detección Precoz del Cáncer/métodos , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Ácido Glucurónico/metabolismo , Glucuronosiltransferasa/antagonistas & inhibidores , Glucuronosiltransferasa/genética , Humanos , Masculino , Antígenos de Histocompatibilidad Menor , Pronóstico , Hiperplasia Prostática/diagnóstico , Hiperplasia Prostática/tratamiento farmacológico , Hiperplasia Prostática/genética , Neoplasias de la Próstata/diagnóstico , Neoplasias de la Próstata/genética , Células Tumorales CultivadasRESUMEN
BACKGROUND: We investigated the androgen receptor (AR) bioluminescense response in serum and urine before and after testosterone challenge in different genotypes of the UGT2B17 enzyme, which catalyses testosterone glucuronidation. MATERIAL AND METHODS: The androgen receptor activity was determined using a yeast-based bioluminescence assay. The androgens were analysed using LC-MS/MS, and the individuals were genotyped for UGT2B17 deletion polymorphism using real-time polymerase chain reaction. RESULTS: The serum concentrations of testosterone and dihydrotestosterone (DHT) were markedly elevated on days 2 and 4 and were still above baseline on day 15 after a dose of 500 mg testosterone enanthate. The androgenic activity in serum increased in parallel and correlated with the hormone concentrations and remained above baseline on day 15. The urinary androgenic activity increased 4-5-fold and was closely related to the unconjugated testosterone and independent of the UGT2B17 genotype. CONCLUSIONS: The AR assay may serve as a complement to the urinary testosterone/epitestosterone (T/E) doping test, because this is profoundly influenced by the UGT2B17 deletion polymorphism. It may also be useful for detection of other illicit androgens in sports, or in the society, or for monitoring and diagnostics of androgen-related disorders.
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Andrógenos , Glucuronosiltransferasa/genética , Receptores Androgénicos/metabolismo , Testosterona/análogos & derivados , Adolescente , Adulto , Dihidrotestosterona/metabolismo , Doping en los Deportes/prevención & control , Relación Dosis-Respuesta a Droga , Eliminación de Gen , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Antígenos de Histocompatibilidad Menor , Polimorfismo Genético/genética , Detección de Abuso de Sustancias/métodos , Testosterona/metabolismo , Adulto JovenRESUMEN
CONTEXT: Androgens play major roles in prostate cancer initiation and development. In prostate cells, the human uridine diphosphate-glucuronosyltransferase (UGT)2B15 and UGT2B17 enzymes inactivate androgens. OBJECTIVE: We investigated in vivo how UGT2B15 and UGT2B17 expressions are affected during prostate cancer development. DESIGN: We conducted an observational study of the UGT2B15 and UGT2B17 mRNA and protein levels. SETTING: The study was conducted at Laval University (Québec, Canada) and at the University of British Columbia (Vancouver, Canada). PATIENTS/PARTICIPANTS: Participants were from a cohort of prostate cancer patients from the Hôtel-Dieu de Québec hospital (Québec; mRNA analyses) and from the Vancouver Prostate Centre tissue bank (Vancouver; tissue microarray experiments). MAIN OUTCOME MEASURES: UGT mRNA and protein levels were determined using real-time PCR and immunohistochemical analyses, respectively. RESULTS: Both UGT2B15 and UGT2B17 mRNA and protein levels were not significantly associated with Gleason score stratification. However, when protein levels were compared to benign prostatic hyperplasia, UGT2B17 was significantly more abundant in all Gleason-scored tumors. By contrast, UGT2B15 levels were significantly reduced in naive and castration-resistant tumors and undetectable in lymph node metastases. Finally, UGT2B17 proteins were 5-fold more abundant in metastases than in benign samples. CONCLUSIONS: The current study reveals that UGT2B15 and UGT2B17 are differentially regulated during prostate cancer progression. Furthermore, this study also identifies the UGT2B15 gene as a negatively regulated target gene in castration-resistant prostate cancer and lymph node metastases.
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Regulación Neoplásica de la Expresión Génica , Glucuronosiltransferasa/genética , Próstata/enzimología , Neoplasias de la Próstata/genética , Progresión de la Enfermedad , Glucuronosiltransferasa/metabolismo , Humanos , Masculino , Antígenos de Histocompatibilidad Menor , Clasificación del Tumor , Próstata/patología , Neoplasias de la Próstata/enzimología , Neoplasias de la Próstata/patologíaRESUMEN
BACKGROUND: Differences in circulating steroid hormone levels have been hypothesized to explain ethnic differences in steroid-related diseases. The aim of this study was to determine the serum levels of a wide panel of steroid hormones, both androgens and estrogens, in healthy middle-aged African-Caribbean and European men. DESIGN AND METHODS: Serum steroid hormone levels were determined in men participating in a systematic public health study funded by the French National Health Insurance system. Blood was collected in the morning from 304 healthy African-Caribbean and European men aged between 40 and 69 years. Serum steroids were measured by mass spectrometry-gas chromatography, except for DHEAS and sex hormone-binding globulin, which were determined by RIA. Data were analyzed in 10-year age intervals by analysis of covariance, with adjustment for age, body mass index, waist-to-hip ratio, tobacco and alcohol consumption, and season of sampling. RESULTS: Compared with Europeans, African-Caribbean men presented significantly higher serum levels of measured bioavailable testosterone, 4-androstenedione (4-dione), and estrone (E1) regardless of the age group, of 5-androstenediol (5-diol) in those aged 40-49 and 50-59 years, and of testosterone (TT) and dihydrotestosterone in those aged 40-49 years. In contrast, European men aged 40-69 years showed significantly higher serum levels of DHEA and DHEAS. CONCLUSIONS: Significant differences in serum steroid hormone levels were observed in middle-aged African-Caribbean and European men. Whether such differences could contribute to ethnic differences in disease risk in adult men remains to be investigated. Some steroids, such as bioavailable TT, 4-dione, 5-diol, and E1, deserve particular attention.
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Población Negra/etnología , Cromatografía de Gases y Espectrometría de Masas , Hormonas Esteroides Gonadales/sangre , Población Blanca/etnología , Adulto , Factores de Edad , Anciano , Androstenodiona/sangre , Biomarcadores/sangre , Región del Caribe/etnología , Estrona/sangre , Cromatografía de Gases y Espectrometría de Masas/métodos , Humanos , Masculino , Persona de Mediana Edad , Radioinmunoensayo , Testosterona/sangreRESUMEN
BACKGROUND: Testosterone is converted to the more potent androgen dihydrotestosterone (DHT) in the prostate. DHT and androgen metabolites are inactivated by uridine diphospho (UDP)-glucuronosyl transferase (UGT) enzymes. Here we have studied the influence of the prostate gland on the systemic levels of DHT. Moreover, genetic variation in androgen metabolizing UGT enzymes and the intra-prostatic levels of glucuronidated DHT metabolites were investigated. METHODS: We collected peripheral serum, serum from the local prostatic veins and prostatic tissue from 25 patients undergoing radical prostatectomy. The serum and intra-tissular level of different androgen metabolites were determined by immunological assays and gas chromatography-mass spectrometry (GCMS), respectively. RESULTS: We found a significant positive correlation between the local prostatic serum DHT levels and (a) prostate weight and (b) circulatory serum levels. There were no correlation between in intra-prostatic hormonal levels and local DHT serum levels. The DHT metabolite 3α-diol-17-glucuronide and 3α-diol-3-glucuronide were significantly associated with UGT2B17 deletion and UGT2B15 Asp85Tyr polymorphisms, respectively. CONCLUSION: These results indicate that local prostatic DHT production has an influence on systemic serum DHT levels. Moreover, our results support the evidence that the prostate is the main DHT producer and that UGTs are important in the intra-prostatic regulation of androgens.
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Dihidrotestosterona/metabolismo , Próstata/metabolismo , Anciano , Estudios Transversales , ADN/química , ADN/genética , Dihidrotestosterona/sangre , Variación Genética , Genotipo , Glucuronosiltransferasa/genética , Glucuronosiltransferasa/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Antígenos de Histocompatibilidad Menor , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , Próstata/enzimología , Estadísticas no ParamétricasRESUMEN
OBJECTIVE: To study the disposition of serum testosterone and seven of its metabolites before and after 2 days of an intramuscular dose (500 mg) of testosterone enanthate in relation to the phosphodiesterase (PDE7B) and the uridine 5'-diphospho-glucuronosyltransferase (UGT2B17) genotypes. METHODS: Patients were genotyped for UGT2B17 deletion polymorphism and single nucleotide polymorphisms in the PDE7B gene. The involvement of PDE7B in hydrolysis of enanthate was assessed in human liver homogenates. RESULTS: Genetic variation in the PDE7B gene was found to be associated with the serum level of testosterone. Individuals homozygous for PDE7B rs7774640 G allele had a smaller increase (2.5-fold) in the serum testosterone levels compared with carriers of the A allele (3.9-fold, P=0.0006). In addition, genetic variation in the PDE7B gene significantly influences the testosterone/epitestosterone ratio, a biomarker of testosterone doping. Our in-vitro incubation studies confirmed that PDE7B serves as a catalyst of the hydrolysis of testosterone enanthate. The UGT2B17 deletion polymorphism did not show any significant association with serum testosterone levels or the other androgen metabolites investigated. CONCLUSION: We have shown that PDE7B is involved in the hydrolysis of testosterone enanthate and that genetic variation in the PDE7B gene is a determinant of the systemic levels of testosterone after administration of testosterone enanthate. It is reasonable to believe that the genetic variation in testosterone bioavailability may be correlated to varying effects of this androgen, whether it is used for replacement therapy or abused in doping. Thus our results may be important to consider in doping test programmes and in therapeutics with androgens and other esterified drugs.