Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Eur J Endocrinol ; 190(1): 54-61, 2024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38141148

RESUMO

OBJECTIVE: Serum testosterone measurements in clinical practice mostly utilize "direct" (non-extraction) immunoassays which have method-specific bias due to steroid cross-reactivity and nonspecific matrix artifacts. Although more accurate, sensitive, and specific liquid chromatography-mass spectrometry (LCMS) dominates in clinical research, the within-person variability of serum testosterone in healthy men using LCMS measurement is not reported. DESIGN: Longitudinal multi-sampling observational study of men in excellent health over 3 months. METHODS: Elite healthy men (n = 325) over 40 years of age in excellent, asymptomatic health provided 9 blood samples over 3 months with serum testosterone, dihydrotestosterone (DHT), estradiol (E2), and estrone (E1) measured by validated LCMS with conventional biochemical and anthropometric variables. RESULTS: Quantitative estimates of within-person variability within day and between day, week, month, and quarter were stable other than an increase due to fasting. The androgen biomarkers most sensitive to age and testosterone among widely used biochemical and anthropometric variables in middle-aged and older men were identified. CONCLUSIONS: This study provides estimates of variability in serum testosterone and the best androgen biomarkers that may prove useful for future studies of androgen action in male ageing.


Assuntos
Androgênios , Testosterona , Pessoa de Meia-Idade , Masculino , Humanos , Idoso , Adulto , Estradiol , Di-Hidrotestosterona , Jejum , Biomarcadores
2.
Math Biosci ; 355: 108940, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36400316

RESUMO

Using a hybrid cellular automaton with stochastic elements, we investigate the effectiveness of multiple drug therapies on prostate cancer (PCa) growth. The ability of Androgen Deprivation Therapy to reduce PCa growth represents a milestone in prostate cancer treatment, nonetheless most patients eventually become refractory and develop castration-resistant prostate cancer. In recent years, a "second generation" drug called enzalutamide has been used to treat advanced PCa, or patients already exposed to chemotherapy that stopped responding to it. However, tumour resistance to enzalutamide is not well understood, and in this context, preclinical models and in silico experiments (numerical simulations) are key to understanding the mechanisms of resistance and to assessing therapeutic settings that may delay or prevent the onset of resistance. In our mathematical system, we incorporate cell phenotype switching to model the development of increased drug resistance, and consider the effect of the micro-environment dynamics on necrosis and apoptosis of the tumour cells. The therapeutic strategies that we explore include using a single drug (enzalutamide), and drug combinations (enzalutamide and everolimus or cabazitaxel) with different treatment schedules. Our results highlight the effectiveness of alternating therapies, especially alternating enzalutamide and cabazitaxel over a year, and a comparison is made with data taken from TRAMP mice to verify our findings.


Assuntos
Neoplasias de Próstata Resistentes à Castração , Humanos , Masculino , Camundongos , Animais , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/patologia , Receptores Androgênicos/genética , Receptores Androgênicos/uso terapêutico , Antagonistas de Androgênios/farmacologia , Antagonistas de Androgênios/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Microambiente Tumoral
3.
Math Biosci Eng ; 18(6): 8577-8602, 2021 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-34814314

RESUMO

Prostate cancer is the fifth most common cause of death from cancer, and the second most common diagnosed cancer in men. In the last few years many mathematical models have been proposed to describe the dynamics of prostate cancer under treatment. So far one of the major challenges has been the development of mathematical models that would represent in vivo conditions and therefore be suitable for clinical applications, while being mathematically treatable. In this paper, we take a step in this direction, by proposing a nonlinear distributed-delay dynamical system that explores neuroendocrine transdifferentiation in human prostate cancer in vivo. Sufficient conditions for the existence and the stability of a tumour-present equilibrium are given, and the occurrence of a Hopf bifurcation is proven for a uniform delay distribution. Numerical simulations are provided to explore differences in behaviour for uniform and exponential delay distributions. The results suggest that the choice of the delay distribution is key in defining the dynamics of the system and in determining the conditions for the onset of oscillations following a switch in the stability of the tumour-present equilibrium.


Assuntos
Modelos Biológicos , Modelos Teóricos , Humanos , Fatores de Tempo
4.
Hum Reprod ; 34(5): 795-803, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30951144

RESUMO

STUDY QUESTION: What is the natural history of outcomes of sperm cryostorage at an Australian tertiary academic centre? SUMMARY ANSWER: Cryostorage is feasible in virtually all men facing gonadotoxic therapy but the timing of sperm disposal varies according to the reason for it. WHAT IS KNOWN ALREADY: Gonadotoxic treatment for cancer or non-cancer diseases damages spermatogenesis and impairs male fertility. Sperm cryopreservation is an established technique to preserve male fertility prior to gonadotoxic treatment. STUDY DESIGN, SIZE, DURATION: A retrospective review of clinical, anthropometric, semen analysis and hormonal data from 1978 to 2017 involving 2717 men comprising 2085 men with cancer, 234 non-cancer disease and 398 healthy controls, in a single tertiary academic centre with the same clinic and laboratory staff. PARTICIPANTS/MATERIALS, SETTING AND METHODS: Sperm output was analysed according to diseases, the feasibility of sperm cryostorage notably for adolescents, regional access to an urban cryostorage facility, the determinants of sperm output and time-dependent disposal of cryostored sperm. Semen samples were assessed by contemporaneous WHO methods. MAIN RESULTS AND THE ROLE OF CHANCE: Of 2085 men with cancer, 904 (43%) had haematological malignancies, 680 (33%) testicular cancers and 136 (6.5%) were adolescents. Most men (89%) and adolescents (80%) could collect sperm. Sperm output for all cancers and non-cancer diseases was lower than controls. Sperm output correlated positively with total testicular volume (r = 0.44, P < 0.0001) and negatively with serum FSH and LH (r = -0.24, -0.12, respectively, both P < 0.0001) but not testosterone. For all stored samples, the median time in cryostorage was 8.5 years, 7% were transferred for use to induce pregnancy (median time 2.5 years) and 62.2% were discarded as no longer needed (return of fertility, 35.9% median 3.5 years; death, 26.3%, median 6.5 years), the high disposal rate reflecting regular annual follow-up to establish ongoing need for continued cryostorage. Cryostorage facilities are not available in remote and rural areas of the State and the proportion of outer regional and remote area residents cryostoring sperm was only about half that compared with urban residents. LIMITATIONS, REASONS FOR CAUTION: This study does not report the pregnancy outcomes of the patients who used the cryostored sperm, due to recent limitations on health data privacy. WIDER IMPLICATIONS OF THE FINDINGS: Sperm cryostorage is feasible for virtually all men, including sufficiently mature adolescents, who can collect semen to insure future paternity as well as making positive psychological preparation for the patient's survival. Disposal of cryostored material when no longer required is efficient with regular follow-up. Sperm cryopreservation should be an integral part of comprehensive treatment plan in men receiving gonadotoxic treatment but remains underutilized. STUDY FUNDING/COMPETING INTEREST(S): There was no external funding for this study and there were no relevant conflicts of interest.


Assuntos
Antineoplásicos/efeitos adversos , Criopreservação , Preservação da Fertilidade/métodos , Recuperação Espermática , Espermatozoides/efeitos dos fármacos , Adolescente , Adulto , Estudos de Viabilidade , Humanos , Masculino , Neoplasias/tratamento farmacológico , New South Wales , Estudos Retrospectivos , Análise do Sêmen , Espermatogênese/efeitos dos fármacos , Adulto Jovem
5.
J Clin Endocrinol Metab ; 103(6): 2277-2283, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29584875

RESUMO

Background: The impact of testosterone (T) treatment on antidoping detection tests in female-to-male (F2M) transgender men is unknown. We investigated urine and serum sex steroid and luteinizing hormone (LH) profiles in T-treated F2M men to determine whether and, if so, how they differed from hypogonadal and healthy control men. Method: Healthy transgender (n = 23) and hypogonadal (n = 24) men aged 18 to 50 years treated with 1000 mg injectable T undecanoate provided trough urine and blood samples and an additional earlier postinjection sample (n = 21). Healthy control men (n = 20) provided a single blood and urine sample. Steroids were measured by mass spectrometry-based methods in urine and serum, LH by immunoassay, and uridine 5'-diphospho-glucuronosyltransferase 2B17 genotype by polymerase chain reaction. Results: Urine LH, human chorionic gonadotropin, T, epitestosterone (EpiT), androsterone (A), etiocholanolone (Etio), A/Etio ratio, dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), and 5α,3α- and 5ß,3α-androstanediols did not differ between groups or by time since last T injection. Urine T/EpiT ratio was <4 in all controls and 12/68 (18%) samples from T-treated men, but there was no difference between T-treated groups. Serum estradiol, estrone, and DHEA were higher in transgender men, and serum T and DHT were higher in earlier compared with trough blood samples, but serum LH, follicle-stimulating hormone, and 3α- and 3ß,5α-diols did not differ between groups. Conclusion: Urine antidoping detection tests in T-treated transgender men can be interpreted like those of T-treated hypogonadal men and are unaffected by time since last T dose. Serum steroids are more sensitive to detect exogenous T administration early but not later after the last T dose.


Assuntos
Androgênios/metabolismo , Estrogênios/metabolismo , Hipogonadismo/tratamento farmacológico , Testosterona/análogos & derivados , Transexualidade/tratamento farmacológico , Adolescente , Adulto , Androgênios/sangue , Androgênios/urina , Androsterona/sangue , Androsterona/urina , Desidroepiandrosterona/sangue , Desidroepiandrosterona/urina , Di-Hidrotestosterona/sangue , Di-Hidrotestosterona/urina , Estradiol/sangue , Estradiol/urina , Estrogênios/sangue , Estrogênios/urina , Estrona/sangue , Estrona/urina , Humanos , Hipogonadismo/sangue , Hipogonadismo/urina , Hormônio Luteinizante/sangue , Hormônio Luteinizante/urina , Masculino , Espectrometria de Massas , Pessoa de Meia-Idade , Testosterona/sangue , Testosterona/uso terapêutico , Testosterona/urina , Pessoas Transgênero , Transexualidade/sangue , Transexualidade/urina , Adulto Jovem
6.
J Steroid Biochem Mol Biol ; 141: 113-20, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24495617

RESUMO

Non-steroidal drugs that increase endogenous testosterone (T) may be used to exploit ergogenic effects of androgens in power sports. While superactive GnRH analog use is suspected, neither screening nor detection tests are developed. This study aimed to determine if (a) stimulation for 5 days by leuprolide (a superactive GnRH analog) of serum and urine steroids and urine LH is reproducible at a 2 week interval, (b) nandrolone decanoate (ND) co-administration masks responses to leuprolide administration, (c) performance of urine measurement of leuprolide and M1, its major metabolite, as a detection test. Healthy men were randomized into a 4 week parallel group, open label clinical study in which all men had daily sc injections of leuprolide (1mg) for 4 days in the 1st and 3rd weeks with hormone-free 2nd and 4th weeks. In the 3rd week, men were randomized to either ND injections or no extra treatment. Serum steroids were determined by liquid chromatography, tandem mass spectrometry (LC-MS), urine steroids by gas chromatography, mass spectrometry (GC-MS), urine leuprolide and M1 by high resolution LC-MS and urine LH by immunoassay. Leuprolide stimulated striking, reproducible increases in serum and urine LH and steroids (serum T, dihydroT (DHT), 3α diol; urine T, epitestosterone (E) and androsterone (A). ND suppressed basal serum T, E2, 3α diol, and urinary E but did not mask or change the magnitude of responses to leuprolide. Urine leuprolide and M1 measurement had 100% sensitivity and specificity in detecting leuprolide administration up to one day after cessation of injections with the detection window between 1 and 3 days after last dose. Screening using urine steroid and LH measurements, optimally by urinary log10(LHxT), correctly classified 82% of urine samples. It is concluded that leuprolide stimulation of endogenous testosterone is reproducible after a 10-day interval, is not masked by ND and is reliably detected by urine leuprolide or M1 measurement for at least 1 day after administration.


Assuntos
Leuprolida/administração & dosagem , Hormônio Luteinizante/sangue , Substâncias para Melhoria do Desempenho/administração & dosagem , Testosterona/sangue , Adulto , Di-Hidrotestosterona/sangue , Di-Hidrotestosterona/urina , Dopagem Esportivo , Estradiol/sangue , Estradiol/urina , Humanos , Leuprolida/farmacocinética , Leuprolida/urina , Hormônio Luteinizante/urina , Masculino , Pessoa de Meia-Idade , Nandrolona/análogos & derivados , Nandrolona/farmacologia , Decanoato de Nandrolona , Substâncias para Melhoria do Desempenho/farmacocinética , Substâncias para Melhoria do Desempenho/urina , Testosterona/urina , Adulto Jovem
7.
Clin Endocrinol (Oxf) ; 77(5): 755-63, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22563890

RESUMO

OBJECTIVE: To determine serum concentrations, intra-individual variability and impact of age-related co-morbidities on serum testosterone (T), dihydrotestosterone (DHT), estradiol (E(2)) and estrone (E(1)) in older men. DESIGN: Observational, repeated measures study. PARTICIPANTS: Men (n = 325) with 40 years and older self-reporting very good or excellent health. MEASUREMENTS: Standardized history, physical examination and collection of nine blood samples at fixed time intervals were measured over 3 months (three at 20 min intervals on days 1 (fasting) and 2 (non-fasting), one at days 7, 30 and 90). Serum T, DHT, E(2) and E(1) (n = 2900, > 99% of scheduled samples) measured by liquid chromatography-tandem mass spectrometry (LC-MS) were analysed by linear mixed model analysis with fasting, age and obesity as covariables. RESULTS: Mean serum T did not vary with age (P = 0·76) but obesity (-0·35 nM per body mass index (BMI) unit, P < 0·0001) and ex-smoker status (-1·6 nM, P < 0·001) had significant effects. Serum DHT was increased with age (+0·011 nM per year, P = 0·001) but decreased with obesity (-0·05 nM per BMI unit, P < 0·0001). Serum E(2) did not vary with age (P = 0·31) or obesity (P = 0·12). Overnight fasting increased (by 9-16%, all P < 0·001) and reduced variability in morning serum T, DHT, E(2) and E(1). Non-fasting serum T and DHT were stable over time (day, week, month or 3 months; P > 0·28). CONCLUSIONS: Serum T, DHT and E(2) displayed no decrease associated with age among men over 40 years of age who self-report very good or excellent health although obesity and ex-smoking status were associated with decreased serum androgens (T and DHT) but not E(2). These findings support the interpretation that the age-related decline in blood T accompanying non-specific symptoms in older men may be due to accumulating age-related co-morbidities rather than a symptomatic androgen deficiency state.


Assuntos
Di-Hidrotestosterona/sangue , Estradiol/sangue , Testosterona/sangue , Idoso , Humanos , Masculino , Pessoa de Meia-Idade
8.
Ann Intern Med ; 153(10): 621-32, 2010 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-21079217

RESUMO

BACKGROUND: Benign prostatic hypertrophy increases with age and can result in substantially decreased quality of life for older men. Surgery is often required to control symptoms. It has been hypothesized that long-term administration of a nonamplifiable pure androgen might decrease prostate growth, thereby decreasing or delaying the need for surgical intervention. OBJECTIVE: To test the hypothesis that dihydrotestosterone (DHT), a nonamplifiable and nonaromatizable pure androgen, reduces late-life prostate growth in middle-aged men. DESIGN: Randomized, placebo-controlled, parallel-group trial. (Australian New Zealand Clinical Trials Registry number: ACTRN12605000358640) SETTING: Ambulatory care research center. PARTICIPANTS: Healthy men (n = 114) older than 50 years without known prostate disease. INTERVENTION: Transdermal DHT (70 mg) or placebo gel daily for 2 years. MEASUREMENTS: Prostate volume was measured by ultrasonography; bone mineral density (BMD) and body composition were measured by dual-energy x-ray absorptiometry; and blood samples and questionnaires were collected every 6 months, with data analyzed by mixed-model analysis for repeated measures. RESULTS: Over 24 months, there was an increase in total (29% [95% CI, 23% to 34%]) and central (75% [CI, 64% to 86%]; P < 0.01) prostate volume and serum prostate-specific antigen level (15% [CI, 6% to 24%]) with time on study, but DHT had no effect (P > 0.2). Dihydrotestosterone treatment decreased spinal BMD (1.4% [CI, 0.6% to 2.3%]; P < 0.001) at 24 months but not hip BMD (P > 0.2) and increased serum aminoterminal propeptide of type I procollagen in the second year of the study compared with placebo. Dihydrotestosterone increased serum DHT levels and its metabolites (5α-androstane-3α,17ß-diol and 5α-androstane-3ß,17ß-diol) and suppressed serum testosterone, estradiol, luteinizing hormone, and follicle-stimulating hormone levels. Dihydrotestosterone increased hemoglobin levels (7% [CI, 5% to 9%]), serum creatinine levels (9% [CI, 5% to 11%]), and lean mass (2.4% [CI, 1.6% to 3.1%) but decreased fat mass (5.2% [CI, 2.6% to 7.7%]) (P <0.001 for all). Protocol-specific discontinuations due to DHT were asymptomatic increased hematocrit (n = 8), which resolved after stopping treatment, and increased prostate-specific antigen levels (n = 3; none with prostate cancer) in the DHT group. No serious adverse effects due to DHT occurred. LIMITATION: Negative findings on prostate growth cannot exclude adverse effects on the natural history of prostate cancer. CONCLUSION: Dihydrotestosterone treatment for 24 months has no beneficial or adverse effect on prostate growth but causes a decrease in spinal but not hip BMD. These findings have important implications for the wider use of nonsteroidal pure androgens in older men. PRIMARY FUNDING SOURCE: BHR Pharma.


Assuntos
Androgênios/administração & dosagem , Di-Hidrotestosterona/administração & dosagem , Próstata/efeitos dos fármacos , Próstata/crescimento & desenvolvimento , Administração Cutânea , Antígenos de Neoplasias/sangue , Composição Corporal/efeitos dos fármacos , Densidade Óssea/efeitos dos fármacos , Colágeno Tipo I/sangue , Di-Hidrotestosterona/sangue , Método Duplo-Cego , Estradiol/sangue , Proteínas Fetais , Géis , Humanos , Hormônio Luteinizante/sangue , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos , Pró-Colágeno , Próstata/diagnóstico por imagem , Antígeno Prostático Específico/sangue , Hiperplasia Prostática/prevenção & controle , Testosterona/sangue , Ultrassonografia
9.
Asian J Androl ; 12(2): 227-33, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20118950

RESUMO

Pain following depot intramuscular (IM) injection of oil vehicle-based drugs has been little studied. This study aimed to determine prospectively the prevalence, determinants, severity and functional consequences of pain during the week after IM injection of 1 000 mg testosterone undecanoate (TU) in a 4-mL castor oil vehicle. Androgen-deficient men receiving regular T replacement therapy at an academic andrology clinic were recruited to report pain scores using a coloured visual linear analogue scale at seven times over the first day and daily for a week after a deep IM gluteal injection. The time course and covariables influencing pain scores were analysed by mixed model analysis of variance (ANOVA). Following 168 injections in 125 men, pain was reported by 80% of men, peaking immediately after injection, reaching only moderate severity, lasting 1-2 days and returning to baseline by day 4. The pain required little analgesic use and produced minimal interference in daily activities. The time course of pain scores was reproducible in the 43 men who underwent two consecutive injections. Pain was more severe in men who had an earlier painful injection, but less severe in older and more obese men. There were negligible differences in post-injection pain experience between experienced nurses administering injections. Deep IM gluteal injection of depot TU in 4-mL castor oil is well tolerated and post-injection pain is influenced by earlier painful injection experience, as well as age and obesity.


Assuntos
Dor/etiologia , Testosterona/análogos & derivados , Análise de Variância , Preparações de Ação Retardada , Humanos , Masculino , Pessoa de Meia-Idade , Testosterona/administração & dosagem , Testosterona/efeitos adversos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA