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At least 1,387 records · Page 77Linked to original sources
PubMed2004

Prevalence of prostate cancer among men with a prostate-specific antigen level < or =4.0 ng per milliliter.

BACKGROUND: The optimal upper limit of the normal range for prostate-specific antigen (PSA) is unknown. We investigated the prevalence of prostate cancer among men in the Prostate Cancer Prevention Trial who had a PSA level of 4.0 ng per milliliter or less. METHODS: Of 18,882 men enrolled in the prevention trial, 9459 were randomly assigned to receive placebo and had an annual measurement of PSA and a digital rectal examination. Among these 9459 men, 2950 men never had a PSA level of more than 4.0 ng per milliliter or an abnormal digital rectal examination, had a final PSA determination, and underwent a prostate biopsy after being in the study for seven years. RESULTS: Among the 2950 men (age range, 62 to 91 years), prostate cancer was diagnosed in 449 (15.2 percent); 67 of these 449 cancers (14.9 percent) had a Gleason score of 7 or higher. The prevalence of prostate cancer was 6.6 percent among men with a PSA level of up to 0.5 ng per milliliter, 10.1 percent among those with values of 0.6 to 1.0 ng per milliliter, 17.0 percent among those with values of 1.1 to 2.0 ng per milliliter, 23.9 percent among those with values of 2.1 to 3.0 ng per milliliter, and 26.9 percent among those with values of 3.1 to 4.0 ng per milliliter. The prevalence of high-grade cancers increased from 12.5 percent of cancers associated with a PSA level of 0.5 ng per milliliter or less to 25.0 percent of cancers associated with a PSA level of 3.1 to 4.0 ng per milliliter. CONCLUSIONS: Biopsy-detected prostate cancer, including high-grade cancers, is not rare among men with PSA levels of 4.0 ng per milliliter or less--levels generally thought to be in the normal range.

Aged↗
PubMed1993

LY191704: a selective, nonsteroidal inhibitor of human steroid 5 alpha-reductase type 1.

Androgens, in particular dihydrotestosterone (DHT), play a key role in differentiation, growth, and maintenance of the mammalian prostate. Production of DHT from testosterone is catalyzed by two distinct membrane-bound steroid 5 alpha-reductase [5 alpha-reductase; 3-oxo-5 alpha-steroid delta 4-dehydrogenase; 3-oxo-5 alpha-steroid:(acceptor) delta 4-oxidoreductase, EC 1.3.99.5] isozymes designated types 1 and 2. Benign prostatic hyperplasia (BPH), a disease that occurs almost universally in males, is characterized by obstructive and irritative urinary voiding symptoms and has been associated with an overproduction of DHT. Recently, steroidal inhibitors of 5 alpha-reductase type 2 have been used successfully for treatment of BPH. Described here is a nonsteroidal inhibitor of 5 alpha-reductase type 1, LY191704 (8-chloro-4-methyl-1,2,3,4,4a,5,6,10b-octaahydro-benzo[f]quinol in-3(2H)-one). This compound was identified based on its capacity to inhibit 5 alpha-reductase activity in a human genital skin fibroblast cell line (Hs68). Surprisingly, LY191704 is inactive when tested in freshly isolated prostate cells obtained from subjects with BPH, whereas previously described 4-azasteroids are active. LY191704 is, however, a potent inhibitor of the 5 alpha-reductase activity of BPH cells that have been maintained in culture. Analysis of human and rat 5 alpha-reductases expressed from transfected cDNAs in simian COS cells indicates that LY191704 is a specific noncompetitive inhibitor of the human 5 alpha-reductase type 1. Taken together, the results suggest that prostate cells have the capacity to express both 5 alpha-reductase isozymes and that LY191704 may be useful in treatment of human endocrine disorders associated with overproduction of DHT by 5 alpha-reductase type 1.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Linear relationships between the ligand binding energy and the activation energy of time-dependent inhibition of steroid 5alpha-reductase by delta 1-4-azasteroids.

The inhibition of steroid 5alpha-reductase (5AR) by Delta(1)-4-azasteroids is characterized by a two-step time-dependent kinetic mechanism where inhibitor combines with enzyme in a fast equilibrium, defined by the inhibition constant K(i), to form an initial reversible enzyme-inhibitor complex, which subsequently undergoes a time-dependent chemical rearrangement, defined by the rate constant k(3), leading to the formation of an apparently irreversible, tight-binding enzyme-inhibitor complex (Tian, G., Mook, R. A., Jr., Moss, M. L., and Frye, S. V. (1995) Biochemistry 34, 13453-13459). A detailed kinetic analysis of this process with a series of Delta(1)-4-azasteroids having different C-17 substituents was performed to understand the relationships between the rate of time-dependent inhibition and the affinity of the time-dependent inhibitors for the enzyme. A linear correlation was observed between ln(1/K(i)), which is proportional to the ligand binding energy for the formation of the enzyme-inhibitor complex, and ln(1/(k(3)/K(i))), which is proportional to the activation energy for the inhibition reaction under the second order reaction condition, which leads to the formation of the irreversible, tight-binding enzyme-inhibitor complex. The coefficient of the correlation was -0.88 +/- 0.07 for type 1 5AR and -1.0 +/- 0.2 for type 2 5AR. In comparison, there was no obvious correlation between ln(1/K(i)) and ln(1/k(3)), which is proportional to the activation energy of the second, time-dependent step of the inhibition reaction. These data are consistent with a model where ligand binding energies provided at C-17 of Delta(1)-4-azasteroids is fully expressed to lower the activation energy of k(3)/K(i) with little perturbation of the energy barrier of the second, time-dependent step.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2005

Role of ciclosporin in steroid-responsive sudden sensorineural hearing loss.

CONCLUSIONS: A subgroup of patients with idiopathic sensorineural hearing loss (SNHL) will have steroid-dependent symptoms which can be confirmed using pure-tone audiometry. Long-term treatment with high-dose corticosteroids exposes patients to potentially serious adverse effects. Immunosuppression with ciclosporin can be an effective and well-tolerated treatment for steroid-responsive sudden SNHL. OBJECTIVE: To highlight ciclosporin as a therapeutic option in the treatment of steroid-responsive sudden SNHL. MATERIAL AND METHODS: A 39-year-old male with idiopathic sudden SNHL that was responsive to corticosteroids was treated with ciclosporin for 18 months. RESULTS: Steroid-dependent SNHL was confirmed on audiological evaluation. Ciclosporin was administered, allowing corticosteroid therapy to be discontinued. Ciclosporin was effective at controlling all symptoms of SNHL. Remission was confirmed objectively with pure-tone audiometry.

Adult↗
PubMed2004

Evaluation of cell permeation of a potent 5alpha-reductase inhibitor using MALDI-TOF MS.

N-(Dicyclohexyl)acetyl-piperidine-4-benzylidene-4-carboxylic acid (1), although a very potent in vitro 5alpha-steroid reductase (5alphaR) type 2 inhibitor, showed only marginal in vivo activity in rats. Since this could be due to hindered cellular uptake of the carboxylic acid, acid (1) and its corresponding methyl ester (1a) were compared with respect to their permeation properties. In the parallel artificial membrane permeation assay (PAMPA), 1a showed a higher %flux of 55 versus 6 for 1. Considering the high potency of 1 and better permeation of 1a, the use of 1a as a prodrug for 1 was explored using the human prostate carcinoma cell line DU145. Esterase activity, a prerequisite for this prodrug concept was detected employing 4-nitrophenyl acetate (4-NPA) as a substrate. After incubation of DU145 cells with 1 and 1a, respectively, permeated 1a and its hydrolysis to 1 were unequivocally observed by MALDI-TOF MS analyses, whereas 1 could not be detected inside the cells above the detection limit. Regarding biological activity, 1a showed a stronger inhibition of 5alphaR in intact DU145 cells than 1 (IC50 values, 4 microM and > 10 microM for 1a and 1, respectively). These results suggest that the in vivo activity of 1 might be increased by the use of its methyl ester prodrug 1a.

Benzoates↗
PubMed1994

Radioimmunoassay for the testosterone 5 alpha-reductase inhibitor turosteride in biological fluids.

An antiserum against turosteride (code name FCE 26073), a potent testosterone 5 alpha-reductase inhibitor, has been raised in rabbits by immunization with an immunogen produced by conjugation of a derivative of FCE 26073 (FCE 27424) to bovine serum albumin. The antiserum was able to distinguish FCE 26073 from its derivatives modified at the 17 beta position and from all the endogenous steroids tested. A radioimmunoassay for the determination of FCE 26073 in human plasma and urine was developed using this antiserum and tritium labeled turosteride. FCE 26073 was extracted from 50 microliters of plasma or 25 microliters of urine using ethyl-ether with a recovery greater than 90%. Using this procedure it was possible to achieve a final limit of quantitation of 142 pg/ml in plasma and 284 pg/ml in urine. The assay was validated in terms of reproducibility, accuracy and precision in the range 3.9-250 pg/50 microliters of plasma and 25 microliters of urine. The plasma concentration of FCE 26073 in a healthy male volunteer who received 0.2 mg of the drug was measured using the radioimmunoassay.

5-alpha Reductase Inhibitors↗
PubMed1997

Prostate disease in older men: 1. Benign hyperplasia.

Medical therapy with alpha 1-adrenergic blockers or 5 alpha-reductase inhibitors offers an alternative to the traditional choices of watchful waiting and surgery. Patients with obstructive symptoms and a small prostate appear to respond to treatment with an alpha 1-adrenergic blocker, while a 5 alpha-reductase inhibitor may be the preferred agent for a large gland.

5-alpha Reductase Inhibitors↗
PubMed2003

Alfuzosin hydrochloride for the treatment of benign prostatic hyperplasia.

The chemistry, pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of alfuzosin hydrochloride in the treatment of benign prostatic hyperplasia (BPH) are discussed. Alfuzosin is a functionally uroselective alpha 1-adrenergic antagonist indicated for the management of moderate to severe BPH. It can improve urinary voiding symptoms and increase urinary flow rates while causing few cardiovascular adverse effects. When administered as an immediate-release (IR) formulation, alfuzosin must be administered twice or thrice daily. The extended-release (ER) formulations of alfuzosin for once- or twice-daily administration are associated with small variations in peak and trough serum drug levels, which may contribute to the lower frequency of cardiovascular adverse effects reported with ER versus IR alfuzosin. Alfuzosin has been shown to improve patients' perception of quality of life, allowing patients to increase their physical activities and improve their ability to handle day-to-day activities. Less significant improvements in patients' sense of well-being and improved sexual functioning have been reported. The usual dose of alfuzosin for patients with BPH is 2.5 mg twice or thrice daily of the IR formulation or 5 mg of ER alfuzosin twice daily or 10 mg of ER alfuzosin once daily. The Food and Drug Administration is currently reviewing the ER 10-mg formulation for once-daily administration. IR alfuzosin is similar to all other second-generation alpha 1-adrenergic antagonists in mechanism of action, clinical efficacy, and adverse effects. No dosage titration is needed for ER alfuzosin, and its onset of peak action is within days of the start of treatment.

Adrenergic alpha-Antagonists↗