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Biomedical subjects

J H MacIndoe

Publications and source records attributed to J H MacIndoe.

At least 19 recordsLinked to original sources
PubMed1998

Effect of exogenous testosterone on prostate volume, serum and semen prostate specific antigen levels in healthy young men.

PURPOSE: We investigate and define the effects of exogenous testosterone on the normal prostate. MATERIALS AND METHODS: A total of 31 healthy volunteers 21 to 39 years old were randomized to receive either 100, 250 or 500 mg. testosterone via intramuscular injection once a week for 15 weeks. Baseline measurements of serum testosterone, free testosterone and prostate specific antigen (PSA) were taken at week 1. Semen samples were also collected for PSA content and prostate volumes were determined by transrectal ultrasound before testosterone injection. Blood was then drawn every other week before each testosterone injection for the 15 weeks, every other week thereafter until week 28 and again at week 40. After the first 15 weeks semen samples were again collected, and prostate volumes were determined by repeat transrectal ultrasound. RESULTS: Free and total serum testosterone levels increased significantly in the 250 and 500 mg. dose groups. No significant change occurred in the prostate volume or serum PSA levels at any dose of exogenous testosterone. Total semen PSA levels decreased following administration of testosterone but did not reach statistical significance. CONCLUSIONS: Despite significant elevations in serum total and free testosterone, healthy young men do not demonstrate increased serum or semen PSA levels, or increased prostate volume in response to exogenous testosterone injections.

Adult↗
PubMed1997

The effects of anabolic steroids on driving performance as assessed by the Iowa Driver Simulator.

The effect of physiologic (100 mg/wk) and supraphysiologic (250 and 500 mg/wk) doses of testosterone cypionate (TC) on automobile driving were studied using the Iowa Driver Simulator. Six normal subject volunteers were studied off TC and on TC once steady-state concentrations were achieved after at least three weeks of dosing. Despite the administration of supraphysiologic testosterone doses, an increase in aggressive driving behavior was not detected. Likewise, corresponding psychometric testing using the Buss-Durkee Hostility Inventory to assess aggression was unable to detect any change in aggression in the test subjects. Although aggressive driving behavior may be increased by testosterone administration, the drug itself may not be responsible for these effects. Supraphysiologic doses greater than 500 mg/wk and a semi-controlled research environment may be necessary to produce this effect since case reports of AAS abuse causing altered driving behavior may be multifactorial in nature.

Adult↗
PubMed1997

Detection of anabolic steroid administration: ratio of urinary testosterone to epitestosterone vs the ratio of urinary testosterone to luteinizing hormone.

Our goal in this study was to determine whether the urinary ratio of testosterone to luteinizing hormone (T/LH) as an indicator of exogenous anabolic steroid (AS) use is superior to the urinary ratio of testosterone to epitestosterone (T/E). After 2 weekly placebo injections, 19 subjects were given testosterone cypionate (TC) injections of 250 or 500 mg/week for 14 weeks followed by 14 weekly placebo injections. Patients were considered to have ceased taking TC if they tested negative 9 weeks after their last injection. For detection of illicit or supraphysiological TC (AS) use, the urinary T/E ratio of > or = 6 yielded a false-negative rate of 46% and a false-positive rate of 4%. However, a urinary T/LH ratio of > or = 30 produced a false-negative rate of only 24% and a false-positive rate of 13%. We conclude that the urinary T/LH ratio of > or = 30 is a more sensitive marker of AS use than the urinary T/E ratio of > or = 6 and remains sensitive for twice as long as urinary T/E.

Adolescent↗
PubMed1997

Testosterone suppression of the HPT axis.

BACKGROUND: Although studies have demonstrated the suppression of normal gonadal function in the experimental setting, the specific mechanisms by which androgenic-anabolic steroids impact male gonadal function remain ill defined. Following 2 consecutive weekly injections of an identically appearing testosterone cypionate (TC) placebo, subjects were randomized to a TC dose of 100 mg/wk, 250 mg/wk, or 500 mg/wk. Following the last weekly injection of active agent the subjects received 12 consecutive weeks of TC placebo injections. RESULTS: Spermatogenesis was impaired by each of the doses of TC employed in this study, but the observed decreases in, sperm count were neither strictly dose dependent nor consistent between individuals treated with the same dose. Basal leuteinizing hormone (LH) and follicle stimulating hormone (FSH) became undetectable 2 weeks after the start of 250 and 500 mg/wk TC injections and were lost within 5 to 6 weeks of starting 100 mg doses. Pituitary gonadotropin responses to leutinizing hormone releasing hormone (LHRH) disappeared more slowly with FSH responses being lost 1 to 3 weeks after the loss of basal FSH activity. Leuteinizing hormone responses to LHRH appeared to be suppressed last, disappearing 4 to 6 weeks after FSH responses to LHRH. CONCLUSIONS: Exogenous testosterone-mediated inhibitory influences on the hypothalamic-pituitary-testicular axis were reversed following the cessation of drug treatment.

Adolescent↗
PubMed1996

The effect of exogenous testosterone on total and free prostate specific antigen levels in healthy young men.

PURPOSE: We evaluated the effect of exogenous testosterone administration on serum total and free prostate specific antigen (PSA) in healthy young men. MATERIALS AND METHODS: Nine volunteers received either 100, 250 or 500 mg. testosterone by intramuscular injection each week for 15 weeks. Blood was drawn every other week for 28 weeks and at week 40. Serum total and free PSA, and total and free testosterone were measured and compared to baseline values. RESULTS: Significant elevations in total and free testosterone occurred but no significant change in serum total and free PSA was detected. CONCLUSIONS: Serum PSA is not responsive to elevated serum testosterone levels in healthy young men. PSA metabolism in the normal prostate is unclear but our findings may have implications for differentiation of pathological conditions of the human prostate.

Adult↗
PubMed1990

Dehydroepiandrosterone and estrone 17-ketosteroid reductases in MCF-7 human breast cancer cells.

The identification of several steroid-transforming enzymes within human breast cancers has led to speculation that the growth of some hormone-responsive tumors might be mediated in part by intracellularly derived estrogens. Reports that MCF-7 human breast cancer cells can transform both estrone (E1)1 to estradiol (E2) and dehydroepiandrosterone (DHEA) to the estrogenic steroid 5-androstenediol (AED), have prompted us to investigate the 17-ketosteroid reductase activities (17-KSR's) which mediate these potentially important reactions. Enzyme assays were performed by quantifying the amounts of [3H]AED or [3H]E2 former from [3H]DHEA or [3H]E1, respectively, by various subcellular preparations from MCF-7 cells under a variety of experimental conditions. DHEA 17-KSR was found to be localized exclusively within cytosol, whereas the E1 17-KSR activity appeared to be nearly equally divided between the soluble and particulate cytoplasmic subfractions. The particulate E1 17-KSR appeared capable of utilizing NADH or NADPH, whereas both the cytosolic form of this enzyme and the soluble DHEA 17-KSR activity showed a strict requirement for NADPH. Although both of the soluble 17-KSR's also showed similar pH optima, several other features suggested that they are different enzymes in MCF-7. E1 did not inhibit the conversion of DHEA to AED, and DHEA did not interfere with the transformation of E1 to E2, indicating that major differences in substrate specificity exist between the two cytosolic activities. Furthermore, DHEA 17-KSR activity within cytosol stored at -20 degrees C deteriorated almost completely over twelve weeks of storage, whereas E1 17-KSR activity remained stable. Finally, although both enzymes were found to be subject to product inhibition, AED inhibited DHEA 17-KSR competitively, whereas cytosolic E1 17-KSR activity was inhibited by E2 in noncompetitive fashion. Studies of the oxidation of E2 to E1 by MCF-7 cells showed that this transformation is catalyzed by both soluble and particulate 17-hydroxysteroid oxidases which utilize either NAD or NADP as cofactor. Having previously reported the presence of a particulate NADP(H)-linked androstenedione (AE) 17-ketosteroid oxidoreductase in MCF-7, we now suggest that at least three different enzymes, one particulate and two soluble forms, participate in the conversion of 17-ketosteroids to their hormonally active 17-hydroxysteroid derivatives within this cell line. The restricted substrate requirements of each enzyme provide a rationale for developing selective enzyme inhibitors which could provide important investigational tools and potentially effective therapeutic agents.

17-Hydroxysteroid Dehydrogenases↗
PubMed1988

The hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate by MCF-7 human breast cancer cells.

Reports of estrone (E1) and dehydroepiandrosterone (DHEA) sulfatase (sulfohydrolase) activities within many human breast cancers have prompted us to undertake the identification and partial characterization of these enzyme activities within MCF-7 human breast cancer cells. Enzyme assays were performed within subcellular preparations and intact cultures by quantifying the total nonpolar 3H-labeled metabolites formed from [3H]E1 sulfate (E1S) and [3H]DHEA sulfate (DHEAS). The results have shown that the hydrolysis of each steroid sulfate is mediated by different particulate enzymes, which demonstrate optimal activity between pH 6.0-7.0. The analysis of enzyme kinetic data showed the Km values of E1S and DHEAS for their enzymes to be approximately 6.3 and 3.6 microM/L, respectively. Neither enzyme was subject to product inhibition. Androsterone sulfate and pregnenolone sulfate produced significant inhibition of E1, but not DHEA, sulfatase activity. E1S inhibited DHEA sulfatase competitively, with an approximate Ki of 11 microM, whereas DHEAS inhibited E2 sulfatase in a noncompetitive fashion, demonstrating an approximate Ki of 0.6 microM. Studies carried out with intact MCF-7 cultures using physiological concentrations of 3H-labeled E1S (2 nM) or DHEAS (1 microM) showed the accumulation of nonpolar metabolites during a 20-h incubation period. When cultures were incubated with similar concentrations of both steroid sulfates the apparent intracellular activity of E1 sulfatase was reduced by approximately 70%, whereas DHEA sulfatase activity remained unchanged. The results of these studies confirm the ability of MCF-7 cells to hydrolyze extracellular E1S and DHEAS, indicate that these reactions are mediated by different enzymes, and demonstrate that DHEAS is a potent inhibitor of MCF-7 E1 sulfatase. Circulating DHEAS, therefore, may substantially limit the ability of most postmenopausal breast cancers to use E1S as a substrate for intracellular estrogen biosynthesis.

Breast Neoplasms↗
PubMed1984

Comparative studies of 5 alpha-reductase inhibitors within MCF-7 human breast cancer cells.

We have compared the inhibitory effects of six synthetic steroid analogs (17 beta-carboxy-4-androsten-3-one benzylanilide (VP-1), 17 alpha-acetoxy-6-methylene-4-pregnene-3,20-dione (VP-2), 6-methylene-4-pregnene-3,20-dione (VP-3), 17 beta-acetoxy-6-methylene-4-androsten-3-one (VP-4), 17 beta-acetoxy-16,16-dimethyl-6-methylene-4-androsten-3-one (VP-5), and 3 beta-hydroxy-16-methylene-5-androsten-17-one (VP-6) ) upon 5 alpha-reductase activity within MCF-7 human breast cancer cells and rat prostate. Enzyme assays were performed by quantifying the amounts of [3H]5 alpha-androstan-3 alpha-17 beta-diol and/or [3H]dihydrotestosterone formed from 40 nM [3H]testosterone within each system. Five microM concentrations of VP-2 and VP-3 inhibited prostatic 5 alpha-reductase by 55 and 65%, respectively, whereas the other analogs showed little activity. In contrast, each of the six analogs was active against MCF-7 homogenate 5 alpha reductase activity. VP-2 and VP-4 demonstrated approx 65 and 70% inhibitions, respectively, whereas the other four compounds inhibited enzyme activity by 40-55% in this system. These results suggest that rat prostate and MCF-7 cells contain different 5 alpha-reductase isozymes. When these agents were examined for 5 alpha-reductase inhibitory activity following 1 h preincubations with intact MCF-7 cultures, VP-1 and 3 demonstrated potencies similar to those in MCF-7 homogenate. The other compounds, however, were far less active under these conditions. Longer culture preincubations (16 h) were associated with substantially increased VP-6 potency, moderate increases for VP-4 and 5, but no change in VP-2 activity. Additional studies examining the abilities of these agents to bind to MCF-7 androgen receptor (AR) and progesterone receptor (PR) revealed moderate AR binding activities of VP-2, 3, and 4, and substantial PR binding for VP-2 and 3. Finally, VP-4 failed to inhibit estrogen-dependent MCF-7 PR synthesis, suggesting that it has no androgenic activity despite its ability to interact with MCF-7 AR.

5-alpha Reductase Inhibitors↗
PubMed1984

Reversible steroid dementia in patients without steroid psychosis.

Six patients developed dementia-like cognitive changes that appeared to result from administration of steroid medications. Four of the patients never showed symptoms of steroid psychosis; the remaining two continued to show steroid dementia well after their steroid psychoses had resolved. The dementia was characterized by deficits in memory retention, attention, concentration, mental speed and efficiency, and occupational performance. All six patients eventually recovered normal mental status following discontinuation or reduction of steroid medications. Larger prospective studies are needed to determine the prevalence and nature of the syndrome.

Adult↗
PubMed1982

The specific binding of estradiol and estrone and the subsequent distribution of estrogen-receptor complexes within MCF-7 human breast cancer cells.

We have examined the specific binding of estradiol (E2) and estrone (E1) within MCF-7 cells using both cytosol and whole cell suspension binding assay techniques. The results of these studies have revealed that each of these estrogens binds the high but different affinity to the same single class of cytosol receptor (ER). The incubation of intact cells with E2 at 37 degrees resulted in the rapid formation, nuclear binding, and nuclear processing of E2-ER complexes. Reduction of incubation temperature to 15 degrees C and 4 degrees C resulted in slowed but continued E2-ER formation and nuclear binding, and in a marked inhibition of nuclear receptor processing. The incubation of intact cells with E1 at 37 degrees also was associated with the formation, nuclear binding, and nuclear processing of estrogen-ER complexes. Interestingly, however, E2 rather the E1 represented the major species of specifically bound estrogen under these conditions. This observation suggests that the estrogenic action of E1 in MCF-7 cells may be mediated largely by the intracellular formation of E2. This phenomenon provides a likely explanation of the unexpected potency of E1 in this system previously observed by other workers. Furthermore, our results suggest that E1 may represent a major source of estrogenic stimulation for some hormone-dependent human breast tumors.

Breast Neoplasms↗
PubMed1982

Comparative studies of aromatase inhibitors in cultured human breast cancer cells.

The presence of aromatase activity, estrogen receptors, and estrogenic responsiveness in MCF-7 human breast cancer cells has allowed this cell line to be used as a unique in vitro system for investigating the biological activities of potentially therapeutic aromatase inhibitors. We now report the results of studies which have examined the cytotoxicity, antiaromatase, and intrinsic estrogenic activities of aminoglutethimide, 1,2-dehydrotestolactone (testolactone), dihydrotestosterone, 4-hydroxy-4-androstene-3,17-dione, and 10-propargylestr-4-ene-3,17-dione within MCF-7 monolayer cultures. Cell viability was determined by trypan blue exclusion, and aromatase activity was assessed by quantifying the amounts of [3H]estradiol formed from [3H]testosterone. Estrogenic activity was assessed by examining the ability of each inhibitor to increase cytoplasmic progesterone receptor and deplete cytoplasmic estrogen receptor concentrations in these cells during a 5-day incubation period. Cytoplasmic progesterone and estrogen receptors were measured by the single-saturating-dose technique using [17 alpha-methyl-3H]-17 alpha, 21-dimethyl-19-norpregna-4,9-diene-3,20-dione and [3H]estradiol as the labeled ligands for each assay, respectively. The results showed that all of these compounds were noncytotoxic aromatase inhibitors in MCF-7 cells but that these agents demonstrated marked differences in inhibitory potency (10-propargylestr-4-ene-3,17-dione greater than 4-hydroxy-4-androstene-3,17-dione much greater than dihydrotestosterone much greater than testolactone = aminoglutethimide). The incubation of cells with 4-hydroxy-4-androstene-3,17-dione resulted in cytoplasmic progesterone and estrogen receptor responses that were similar in magnitude to those observed in other cultures incubated with equimolar concentrations of estradiol. None of the other four agents demonstrated estrogenic activity in this system. However, we have previously observed that dihydrotestosterone has substantial antiestrogenic action in this system. Taken together, these results indicate that some aromatase inhibitors may influence the hormonal regulation of human breast cancer cells by more than one mechanism.

Aminoglutethimide↗
PubMed1981

The specific binding of androgens and the subsequent distribution of androgen-receptor complexes within MCF-7 human breast cancer cells.

Using a whole cell suspension assay technique, we have examined both the specific binding of testosterone (T) and dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) (DHT) and the subsequent distribution of androgen binding activity within MCF-7 human breast cancer cells. We have observed that both androgens are bound with high affinity to the same single class of receptor which is present at a concentration of approximately 8,000 sites per cell. The incubation of cells with either T or DHT was followed by the nuclear accumulation of specifically bound ligand which increased to maximal values within 1 h and then decreased thereafter. However, only about 30% of the total cellular specific binding activity observed with either androgen was localized within the nuclear compartment at any time during a 4 h incubation. Further examination of the extranuclear binding component suggested that a substantial portion of this activity was localized to the particulate fraction of the cytoplasm. The results of these studies suggest that both T and DHT are capable of exerting biological activity within MCF-7 cells, and raise the interesting possibility that androgen-receptor complexes may participate in the direct regulation of mitochondrial and/or microsomal function in this system.

Breast Neoplasms↗
PubMed1981

Steroid-metabolizing enzymes in human breast cancer cells. II. 5 alpha-Reductase, 3 alpha-hydroxysteroid oxidoreductase, and 17 beta-hydroxysteroid oxidoreductase.

Evidence that some human breast cancers can form biologically active sex steroids from extracellular precursors has prompted us to investigate several human breast cancer cell lines for similar steroidogenic capability. We have previously reported that MCF-7 and MDA-MB-231 human breast cancer cells can transform testosterone to estradiol but that aromatase activity is not apparent in the HBL-100 human breast cell line. We report here the presence of 17 beta-hydroxysteroid oxidoreductase, 5 alpha-reductase, and 3 alpha-hydroxysteroid oxidoreductase activities in all three cell lines. Characterization of these enzymes in MCF-7 cells indicated that the intracellular location, temperature and pH optima, cofactor requirements, and apparent substrate affinities for each are generally similar to those described in several other mammalian systems. The presence of 17-hydroxysteroid oxidoreductase, aromatase, 5 alpha-reductase, and 3-hydroxysteroid oxidoreductase activities in MCF-7 suggests the possibility that the hormonal regulation of these human breast cancer cells may be mediated in part by intracellular estrogen and/or androgen biosynthesis.

17-Hydroxysteroid Dehydrogenases↗
PubMed1981

An antiestrogenic action of androgens in human breast cancer cells.

We have recently observed that androgens prevent the estrogen-dependent augmentation of cytoplasmic progesterone receptor (PRc) in MCF-7 human breast cancer cells and now report the results of studies that further characterize this new example of sex steroid antagonism. Using a single saturating dose assay to monitor changes in MCF-7 PRc concentration, we have observed that androgens are capable of inhibiting both the estrogenic induction and the ongoing stimulation of PRc synthesis, but have no apparent effect upon basal concentrations of this receptor. Both testosterone and dihydrotestosterone (DHT) demonstrate similar degrees of antiestrogenic activity at concentrations between 10(-10)--10(-8) M. Furthermore, a 10(-8)-M concentration of either androgen completely inhibits the stimulation of PRc synthesis by 10(-11)--10(-8) M 17 beta-estradiol (E2). This inhibitory effect is maintained during the continued presence of either testosterone or DHT, but rapidly disappears after the withdrawal of androgen from the culture medium. The specific nuclear binding of 17 beta-[3H]estradiol over time appears to be similar in cultures incubated in the presence and absence of 10(-8) M DHT. This observation suggests that androgens do not inhibit estrogen action by interfering with the formation, activation, nuclear binding, or nuclear processing of estrogen-receptor complexes. The estrogenic stimulation of PRc is not diminished by the 5 beta-epimer of DHT, and the inhibitory activity of DHT itself is blocked by several different antiandrogens. These findings provide substantial support for the concept that the antiestrogenic effect of androgens is mediated by an androgen receptor mechanism. These results may provide new insights into the clinically apparent antagonistic effects of estrogens and androgens upon both normal and malignant human breast tissues.

Androgens↗
PubMed1979

Estradiol formation from testosterone by continuously cultured human breast cancer cells.

Two human breast cancer cell lines (MCF-7 and MDA-MB-231) and one cell line derived from normal human breast (HBL-100) were examined for the presence of aromatase activity by determining the amounts of [3H]estradiol ([3H]E2) formed by cell cultures incubated with [3H]testosterone. Aromatase activity was demonstrable in both breast cancer cell lines, but estradiol synthesis was not observed in HBL-100 cultures. The [3H]E2 content of MCF-7 cultures rose as a function of incubation time and substrate concentration. Furthermore, [3H]E2 formation by this cell line was suppressed by several known inhibitors of human placental aromatase. These observations represent the first evidence that some lines of continuously cultured human breast cancer cells, like some human breast tumors, are capable of forming estrogen from an extracellular precursor steroid. Cultured breast cells may provide model systems for investigating the relative importance of intracellular estrogen formation in the regulation of human breast cancer cell growth.

Aromatase↗