Biomedical subjects

P B Grino

Publications and source records attributed to P B Grino.

9 recordsLinked to original sources

PubMed1993

Maximum urinary flow rate by uroflowmetry: automatic or visual interpretation.

We measured the maximum urinary flow rate monthly for 1 year by uroflowmetry in 1,645 patients in a double-blind, placebo-controlled study of finasteride therapy for benign prostatic hyperplasia. Patients were randomized to receive placebo (555) or finasteride (1,090). A total of 23,857 flow measurements was obtained. Because of the presence of artifacts on many uroflow curves, we read the maximum urinary flow rate values manually and compared them to the values provided electronically by the uroflowmeter. On average, the manually read values were 1.5 ml. per second lower than the machine read values. Artifacts causing a difference of 2 ml. per second or more between the 2 methods were found in 20% and of more than 3 ml. per second in 9% of the tracings. The difference between treatment groups in mean maximum urinary flow rate change at the end of the study was the same with both reading methods. However, confidence intervals were 15 to 25% larger for the machine read compared to the manually read values. This larger variability in machine read maximum urinary flow rate has a marked negative impact on the power of statistical tests to assess any given difference in maximum urinary flow rate between treatment groups. Furthermore, it increases sample size requirements by 50% to achieve any given statistical power. We conclude that maximum urinary flow rate artifacts contribute significantly to the variability of maximum urinary flow rate measurement by uroflowmetry. Manual reading of the maximum urinary flow rate eliminates an important fraction of such variability.

5-alpha Reductase Inhibitors↗

PubMed1992

Validation of a symptoms questionnaire for benign prostatic hyperplasia.

We developed a questionnaire to assess the effect of finasteride on symptoms of benign prostatic hyperplasia (BPH) by modifying that of Boyarsky (1977). To validate the questionnaire, a cohort study was conducted in 2 groups of patients with BPH and 3 control groups without BPH. The BPH groups were: (1) 34 patients before TURP (transurethral resection of the prostate), average age 68 years; (2) 65 patients after TURP, average age 68 years; (3) 40 patients after other nonserious nonurological surgery, average age 50 years; (4) 14 healthy non-BPH volunteers, average age 58 years; and (5) 73 healthy non-BPH volunteers, average age 37 years. The questionnaire was administered once to all subjects, and a subset responded to a second administration. Mean total symptoms scores (TSS) from the initial questioning were 6.4, 3.2, 2.9, 2.6, and 1.6 for the 5 groups, respectively (pooled SD = 3.3); mean total troublesome symptoms scores (TTSS) were 4.8, 2.1, 1.4, 1.1, and 0.6, respectively (pooled SD = 2.2). All other groups were significantly less symptomatic and troubled than the pre-TURP group, and all surgical groups were significantly more so than the younger volunteer group. These data demonstrate the discriminant validity of the questionnaire. Corroborating prior data [Gregg et al., 1990], responsiveness was shown by the 3.7-point mean TSS improvement in response to TURP, which was significantly different from the near-zero changes in the other groups. Reproducibility was shown by kappa statistics being nearly all greater than 0.75 and an intraclass correlation coefficient of 0.64; construct validity and reliability were demonstrated by correlation (r = 0.7) with a general urination problems question; and internal consistency was documented by Cronbach's alpha values of approximately 0.6. We conclude that this questionnaire is a useful and validated tool for assessing BPH symptoms.

Evaluation Studies as Topic↗

PubMed1991

A mutation in the DNA-binding domain of the androgen receptor gene causes complete testicular feminization in a patient with receptor-positive androgen resistance.

Androgen resistance is associated with a wide range of quantitative and qualitative defects in the androgen receptor. However, fibroblast cultures from approximately 10% of patients with the clinical, endocrine, and genetic features characteristic of androgen resistance express normal quantities of apparently normal androgen receptor in cultured genital skin fibroblasts (receptor-positive androgen resistance). We have analyzed the androgen receptor gene of one patient (P321) with receptor-positive, complete testicular feminization and detected a single nucleotide substitution at nucleotide 2006 (G----C) within the second "zinc finger" of the DNA-binding domain that results in the conversion of the arginine residue at position 615 into a proline residue. Introduction of this mutation into the androgen receptor cDNA and transfection of the expression plasmid into eukaryotic cells lead to the synthesis of a receptor protein that displays normal binding kinetics but is inactive in functional assays of receptor activity. We conclude that substitution mutations in the DNA-binding domain of the androgen receptor are one cause of "receptor-positive" androgen resistance.

Androgen-Insensitivity Syndrome↗

PubMed1990

Androgen resistance due to decreased amounts of androgen receptor: a reinvestigation.

To provide insight into the pathogenesis of the androgen resistance in a previously described family with X-linked Reifenstein syndrome, we have systematically assessed a variety of parameters of androgen receptor function in fibroblasts cultured from scrotal skin biopsies. We assessed the amount of high affinity binding, the affinity of ligand binding to the receptor, the upregulation of androgen receptor levels by androgen, the stability of ligand binding in intact fibroblasts at high temperature, the dissociation of ligand from the receptor, the intranuclear localization and salt elution profiles of ligand-receptor complexes, and the ultracentrifugation characteristics of the ligand-receptor complexes. Since the only parameter found to be abnormal is a decreased amount of receptor, we conclude that the underlying mutation in this family influences the amount rather than the structure of the androgen receptor protein.

Androgens↗

PubMed1990

Testosterone at high concentrations interacts with the human androgen receptor similarly to dihydrotestosterone.

Testosterone and dihydrotestosterone are believed to exert their androgenic effects by interacting with a single intracellular receptor protein in androgen target tissues. During fetal life, however, testosterone mediates the virilization of the Wolffian ducts into the epididymis, vas deferens, and seminal vesicles, whereas the urogenital sinus and external genitalia require the in situ conversion of testosterone to dihydrotestosterone to undergo male development. The reason why the signal provided by testosterone needs to be amplified in some androgen target tissues but not in others remains an enigma. To provide insight into the different actions of these androgens we studied their interaction with the human androgen receptor in fibroblasts cultured from the genital skin of a patient with 5 alpha-reductase deficiency. Dihydrotestosterone was formed in negligible amounts in these cells, and in some experiments the residual 5 alpha-reductase activity was further blocked with the 5 alpha-reductase inhibitor finasteride. Saturation analysis in fibroblast monolayers disclosed similar amounts of binding with testosterone and dihydrotestosterone, and the affinity of binding of dihydrotestosterone was, on the average, about 2-fold greater than that of testosterone. [3H]Testosterone also exhibited a 5-fold faster dissociation rate from the receptor than [3H]dihydrotestosterone. In thermolability experiments the [3H]testosterone-receptor complex displayed marked instability at 42 C with 2 nM [3H] testosterone, whereas with 20 nM [3H]testosterone, receptor stability was similar to that seen with [3H]dihydrotestosterone. In up-regulation experiments, 2 nM [3H]testosterone produced a 34% increase in specific androgen receptor binding after 24 h, whereas 20 nM [3H]testosterone produced an average increase of 64%. Our results suggest that the weaker androgenic potency of testosterone compared to that of dihydrotestosterone resides in its weaker interaction with the androgen receptor, most clearly demonstrable as an increase in the dissociation rate of testosterone from the receptor. When present in relatively high concentrations, however, testosterone overcomes this defect by mass action.(ABSTRACT TRUNCATED AT 400 WORDS)

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

PubMed1990

Estrogen and androgen production rates in two brothers with Reifenstein syndrome.

Defects of the androgen receptor in 46,XY individuals cause aberrant virilization that varies from a female phenotype to men with minor defects. More severely affected individuals also develop gynecomastia associated with enhanced estradiol secretion by the testis. However, the degree of breast development does not correlate with the rate of estrogen production, leading us to propose that feminization is a function of the degree of androgen resistance as well as the rate of estrogen formation. To test this hypothesis we measured estrogen and androgen formation in two brothers with perineoscrotal hypospadias and severe gynecomastia (the Reifenstein phenotype) due to a mutation that impairs androgen receptor function. Rates of estradiol production (60 and 70 micrograms/day) were elevated, but were not as high as in previously studied men with a similar phenotype. We conclude that the variable degree of feminization in this disorder cannot be explained by androgen resistance alone.

Adult↗

PubMed1989

Androgen resistance associated with a qualitative abnormality of the androgen receptor and responsive to high dose androgen therapy.

A 46,XY infant with perineoscrotal hypospadias and microphallus was identified in a family in which seven individuals have severe hypospadias that is inherited in a pattern compatible with an X-linked defect. The infant had small testes that were palpable in the labioscrotal folds, the proximal urethra was male in character, and there was no vagina. Serum testosterone rose from 0.5 to 5.1 nmol/L in response to hCG, and there was a negligible clinical response to a short term course of testosterone enanthate. A clinical diagnosis of male pseudohermaphroditism due to androgen resistance was made. Studies in cultured genital skin fibroblasts disclosed normal 5 alpha-reductase activity, a normal amount of high affinity dihydrotestosterone binding, and normal up-regulation of androgen receptors when monolayers were incubated with dihydrotestosterone or mibolerone. Fibroblast cytosol preparations contained a normal 7-8S sedimenting peak of androgen binding. However, androgen binding in monolayers decreased 60% when the assay temperature was raised from 30 to 41 C, and the dissociation rate of ligand from the receptor was enhanced 5-fold compared to the control value, establishing the diagnosis of androgen resistance due to a qualitative abnormality of the androgen receptor. Because of parental decision to raise the patient as a male, he was given two courses of high dose testosterone cypionate when he was 2.5 and 3.5 yr old (100 mg every 2 weeks for six doses). This treatment produced significant phallic growth, making it possible to undertake surgical correction of the hypospadias. We postulate that the impairment of androgen receptor function was overcome in part by the large dose of androgen.

Chorionic Gonadotropin↗

PubMed1988

A mutation of the androgen receptor associated with partial androgen resistance, familial gynecomastia, and fertility.

A family is described in which gynecomastia and undervirilization in five men (four of whom have fathered children) were inherited in a manner compatible with an X-linked defect. Three members from whom blood could be obtained had supranormal serum testosterone and normal LH and FSH levels. One man had severe oligospermia with decreased motility, and one had normal sperm density and motility. In fibroblasts cultured from genital skin biopsies from two of the men, the levels of androgen receptor and affinity of binding of receptor to dihydrotestosterone were normal. However, androgen binding in fibroblast monolayers was thermolabile, up-regulation of receptor levels did not occur after prolonged incubation of monolayers with dihydrotestosterone or methyltrienolone, and dissociation rates at 37 C were increased with the synthetic androgen mibolerone. In addition, in cytosol preparations the androgen receptor protein was unstable. This disorder probably represents the most subtle functional abnormality of androgen receptor characterized to date, since it is compatible with normal male phenotypic development and in some affected men with fertility. It follows that infertility is not an invariable feature of androgen resistance as we previously suggested.

Adolescent↗

PubMed1987

Transformation of the androgen receptor to the deoxyribonucleic acid-binding state: studies in homogenates and intact cells.

Transformation of the [3H]dihydrotestosterone-receptor complex to the DNA-binding state was studied in intact monolayers and in homogenates of cultured human fibroblasts and mouse L-cells. When homogenates of either cell type were prepared in low salt buffer, incubated at 0 C with [3H]dihydrotestosterone, chromatographed on DNA-Sepharose, and eluted with a NaCl gradient, the receptor complex was eluted at 25 mM NaCl (peak A). After incubation of the homogenate at 25 C for 20 min, peak A decreased in amplitude. The major peak of the receptor from human fibroblasts eluted at 100 mM NaCl, while that from L-cells eluted at 170 mM NaCl (peak B). Flow-through fractions contained only minimal amounts of transformable dihydrotestosterone-receptor complex under the same conditions. Furthermore, isolated peak A could be converted to peak B by the same warming process. The appearance of peak B was prevented when 10 mM, but not 1 mM, sodium molybdate was present during the homogenization process. Unoccupied receptor was recovered exclusively in peak A both at 0 C and after incubation at 25 C. When intact fibroblast and L-cell monolayers were incubated with [3H]dihydrotestosterone at 37 C, all receptor in both cytosol and nuclear extract was recovered in peak B. In sucrose density gradient centrifugation, peak A was 6-8S in size, and peak B was 4.6S. These findings suggest that peak A corresponds to the nontransformed and peak B to the transformed states of the androgen receptor; the transformation reaction may be the consequence of a dissociation of a macromolecular complex into subunits; and sodium molybdate acts to stabilize the macromolecular complex.

Animals↗