Biomedical subjects

M Fujimoto

Publications and source records attributed to M Fujimoto.

At least 397 records · Page 22Linked to original sources

PubMed1990

Monoclonal antibodies to endothelin: application for sandwich immunoassays.

We established 16 monoclonal antibodies (MAbs) to endothelin (ET), a novel and potent vasoconstrictor. They were classified into two groups: eight of them reacted with the C-terminal portion of ET, and the other eight reacted with the non-C-terminal portion. We constructed the sandwich enzyme linked immunosorbent assays (ELISAs) using a combination of a MAb belonging to the former with that belonging to the latter, and could detect about 400 pg/ml of ET.

Animals↗

PubMed1990

Clinical study of pirarubicin for breast cancer in Japan. Clinical Study Group of THP for Breast Cancer in Japan.

The efficacy and toxicity of (2''R)-4'-O-tetrahydropyranyl adriamycin (THP) were assessed in the treatment of patients with advanced breast cancer by the Japan THP Study Group. Mean plasma levels of THP after single-dose administration revealed triexponential decay characterized by an initial half-life of 0.89 h. A higher concentration of THP was obtained in the metastatic lymph nodes than in the breast cancer tissue at 4 h after administration (4.01 vs. 1.17 micrograms/g). Whereas 1 complete (CR) and 12 partial response (PR) were observed in 56 evaluable patients after administration of THP alone (23.2%), 1 CR and 12 PR were observed in 37 evaluable patients who had combination therapy including THP (35.1%). Multivariate analysis of prognostic factor revealed that the site of metastases had the most valuable prognostic significance; second was irradiation in the previous treatment, and third was the disease-free interval. Life-table analysis adjusted with the Cox proportional hazard model revealed a similar survival curve of patients receiving THP-cyclophosphamide, adriamycin, and 5-fluorouracil (CAF) to that of those receiving CAF only in spite of the low incidence of toxicity in the THP therapy.

Adult↗

PubMed1990

Plasma active and inactive renin concentrations in children.

Plasma active and inactive renin concentrations (PARC and PIRC) were measured by immunoradiometric assay. Age-related changes in PARC, PIRC and the ratio of PARC/PIRC were studied in 78 normal children, age 1 month to 15 years. The effects of upright position for 15 min were also investigated in 7 postmenarcheal girls. PARC and PIRC in infants were significantly higher than in older children and their ratio of PARC/PIRC was significantly lower than in prepubertal children. During puberty, PARC, PIRC and their ratio were higher in premenarcheal girls than in postmenarcheal girls. In the upright position, PARC, PIRC and the ratio were increased significantly. These finding suggest that: (1) the production of inactive renin is increased but the activation of renin may be lowered in infants; (2) the activation of renin is affected by the menstrual cycle, and (3) the production and activation of renin are increased during short term standing.

Adolescent↗

PubMed1990

[Antihypertensive effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, in stroke-prone spontaneously hypertensive rats (SHRSP)].

Effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, on blood pressure and hypertensive complications in stroke-prone spontaneously hypertensive rats (SHRSP) were investigated. Betaxolol was provided in a dose of 33 +/- 1.8 mg/kg/day, orally in drinking water, throughout the experimental period. The chronic treatment with betaxolol inhibited the development of hypertension in SHRSP and reduced values of blood urea nitrogen, creatinine, total cholesterol, free cholesterol, triglyceride, phospholipid and HDL-cholesterol in serum. Treatment with betaxolol apparently inhibited the incidence of hypertensive lesions such as cardiac fibrosis, mesenteric vasculitis, proliferative and/or necrotic vasculitis and glomeruli showing collapse or vasculitis in the kidneys. To shorten the time before the onset of hypertension and the subsequent stroke, SHRSP were kept on a SP diet containing 0.39% Na instead of the F-2 diet. When the SHRSP were kept on the SP diet, all of the control SHRSP had cerebral apoplexy and severe hypertensive lesions in the heart and kidney. When betaxolol was chronically administered to SHRSP, cerebral apoplexy and hypertensive lesions in the heart and kidney were inhibited, but the effect on blood pressure was slight. Treatment with betaxolol reduced serum creatinine levels. Our observations show that betaxolol reduces blood pressure and potently inhibits hypertensive complications in SHRSP.

Adrenergic beta-Agonists↗

PubMed1990

Comparison of the effects of bilobol and 12-O-tetradecanoylphorbol-13-acetate on skin, and test of tumor promoting potential of bilobol in CD-1 mice.

Bilobol, isolated from ginkgo fruit pulp, has been noted to be a strong skin irritant like 12-O-tetradecanoylphorbol-13-acetate (TPA), a tumor-promoter in the skin. A comparative investigation of morphological changes induced by bilobol and TPA induced in the skin of CD-1 mice, and an assessment of the skin tumor promoting potential of bilobol were therefore performed. In experiment I, mice received a single application of 2.5, 50 or 1000 micrograms of bilobol, or 0.1 or 2.5 micrograms of TPA on the right ear. The 50 or 1000 micrograms bilobol and 2.5 micrograms TPA doses caused ear redness, epidermal thickening and inflammatory infiltration. The dose of 2.5 micrograms of TPA, which is usually used as tumor promoter in skin carcinogenesis, was equivalent to 50 micrograms of bilobol in irritant effect. Thus, 50 micrograms of bilobol was used for the promotion testing (experiment II) in CD-1 mice initiated with 100 micrograms of 7, 12-dimethylbenz[a]anthracene (DMBA). Treatment with either 10 or 50 micrograms bilobol twice a week for 30 weeks did not result in any tumor development, thus suggesting that bilobol is not a complete promoter of skin carcinogenesis, despite generation of inflammation.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1990

Relationship between cytosolic activities of calcium and pH in frog proximal tubules.

To examine the effect of acid-base changes on the cytosolic calcium activity, (Ca)i, we used ion-selective microelectrodes in doubly perfused preparations of bullfrog kidney proximal tubule. For analyzing the time course of changes in (Ca)i and cytosolic pH (pHi) in response to peritubular acid or alkali perfusion and high K+, low Na+, or low Ca2+ perfusion single-barreled PVC-resin Ca2(+)-selective microelectrodes and double-barreled pH-sensitive microelectrodes were inserted into the cells. Control values (mean +/- S.E., number of observations) of (Ca)i and pHi averaged 17.2 +/- 1.0 nM (n = 25) and 7.39 +/- 0.01 (n = 25), respectively. Peritubular perfusion with a low pH perfusate (low HCO3-, pH 6.7) was found to reduce (Ca)i to about 4 nM in association with a moderate degree of cell acidification (to pH 7.09) and depolarization of the peritubular membrane potential (control -60 mV to experimental approximately -40 mV). Further, peritubular alkalinization (high HCO3- 30 mM, pH 8.0) induced a transient elevation of (Ca)i and hyperpolarization. In contrast, the peritubular perfusion of high K+ solution induced a rise of (Ca)i and pHi with membrane depolarization, while low Na+ perfusion decreased (Ca)i and pHi. These results support the view that 1) the experimentally induced changes in the membrane potential may be ascribed in large part of alterations of pH-sensitive conductance across the peritubular membrane, and 2) the cell pH and extracellular Ca2+ affect the cytosolic Ca2+ of the proximal tubule.

Acid-Base Equilibrium↗

PubMed1990

Effects of dopamine on the transport of Na, H, and Ca in the bullfrog proximal tubule.

UNLABELLED: To study effects of dopamine (DA, 10(-6) M) on ion transport processes in proximal tubular cells, we used Na(+)-, H(+)-, and Ca2(+)-selective microelectrodes in doubly-perfused bullfrog kidneys. The peritubular membrane potential difference (EM) and cytosolic Na+, Ca2+, and H+ activities ((Na)i, (Ca)i, and pHi) were measured continuously after peritubular administration of DA or dibutyryl-cyclic AMP (db-cAMP, 10(-4) M). Results obtained are as follows. 1) DA induced a decrease of (Na)i by 4.2 mM, but during the luminal perfusion of 0.5 mM Na+ solution, DA decreased (Na)i only by 1.4 mM. 2) DA produced a delayed fall of (Ca)i by 8 nM. 3) DA produced hyperpolarization of EM by 5-7 mV. 4) Peritubular perfusion with high K+ (35 mM) solution produced about 30 mV depolarization of EM. DA added to high K+ perfusate induced 38 mV depolarization. 5) DA increased pHi by 0.07. 6) DA produced almost the same changes in (Na)i, (Ca)i, EM, and pHi as those induced by db-cAMP. 7) Effects of DA on EM and (Na)i were inhibited by dopamine1 (DA1) antagonist. CONCLUSIONS: Effects of DA on ion transport in the proximal tubular cells are mediated by the adenylate-cyclase-cAMP system. The activation of this system induces 1) suppression of Na+ entry step across the luminal membrane, 2) an increase of K+ permeability in the peritubular membrane, 3) cytosolic alkalinization with vesicular accumulation of H+ by enhancing H+ pump, and 4) a decrease of (Ca)i possibly by restricting Ca2+ entry across the luminal membrane and activating Ca2+ pump in the peritubular membrane or subcellular organelles.

Adenylyl Cyclases↗

PubMed1990

Potassium permeability of luminal and peritubular membranes in the proximal tubule of bullfrog kidneys.

Using double-barreled K(+)-selective or conventional voltage microelectrode, K+ permeability of the luminal membrane of renal proximal tubule was investigated in comparison with that of the peritubular membrane in doubly-perfused bullfrog kidneys. A decade change in K+ concentration of the luminal perfusate from 3.5 (control) to 35 mM (high K+) induced depolarization in the luminal membrane potential by 11.2 mV with a slight elevation of intracellular K+ activity, (K)i, while those of the peritubular perfusate depolarized peritubular membrane potential by 31.6 mV with a moderate rise of (K)i by 8.0 mEq. The transport number for K+ (tK) in the luminal membrane was about one-third of that in the peritubular membrane. Both luminal and peritubular administrations of Ba2+ (4 mM) additively depolarized membrane potential. The magnitude of Ba2(+)-induced depolarization in the luminal membrane was about one-fourth of that in the peritubular membrane. The high K(+)-induced depolarization elicited from one-side perfusion was hardly affected by Ba2+ which was given from the other side. From these results we conclude that the transport number of K+ in the luminal and peritubular membranes of the proximal tubular epithelium is in the range of 0.17-0.32 and 0.52-0.66, respectively.

Animals↗

PubMed1990

Intracellular calcium measurements with PVC-resin Ca-selective microelectrodes in frog proximal tubules and sartorius muscle fibers.

To measure ion activity of intracellular calcium, (Ca)i, we manufactured a Ca2(+)-selective microelectrode based on a neutral carrier, ETH-1001, with or without polyvinylchloride column (PVC-resin). Before and after cell impalements (n = 7), PVC-resin Ca2(+)-selective microelectrodes exhibited Nernstian slopes in the range of p(Ca) from 3 to 7 (the mean slope constant: 29.1 and 29.4 mV/p(Ca), respectively) and sub-Nernstian slopes between p(Ca) = 7 and 8 (21.6 and 21.1 mV/p(Ca]. Individual detection limits of PVC-resin microelectrodes averaged p(Ca) = 8.5 before and 8.3 after cell impalements. In contrast, the non-PVC-resin microelectrode exhibited a poor response between p(Ca) = 7 and 8 especially after cell impalements. Normal values obtained with the PVC-resin microelectrode for (Ca)i of proximal tubule cells and resting sartorius muscle fibers in the bullfrog averaged 18 +/- 2 (n = 10) and 12 +/- 2 (n = 7) nM (mean +/- S.E., number of observations), respectively. We conclude that 1) the PVC-resin microelectrode is a useful tool for measuring intracellular ion activities, and 2) the values of intracellular Ca2+ activity of the proximal tubule and skeletal muscle fibers measured with this microelectrode are in a lower range among the various values reported before with the other methods.

Animals↗

PubMed1990

Neuropeptide Y receptor in cultured vascular smooth muscle cells: ligand binding and increase in cytosolic free Ca2+.

We have previously shown that neuropeptide Y (NPY) increases cytosolic free Ca2+ concentration [( Ca2+]i) in porcine aortic smooth muscle cells. In this study, specific NPY receptor binding sites were identified in the cells by use of [125I]Bolton-Hunter NPY [( 125I]BH-NPY). Binding was to a single population of the sites with a Kd of 1.1 +/- 0.2 nM and a Bmax of 0.68 +/- 0.10 pmol/mg protein. [125I]BH-NPY binding was displaced by NPY-related peptides including members of the pancreatic polypeptide (PP) family. The potency of these peptides other than human PP for displacing [125I]BH-NPY binding was substantially consistent with their potency for increasing [Ca2+]i. Human PP had no effect on [Ca2+]i even at 10(-5) M, but it inhibited the NPY-induced increase in [Ca2+]i with a potency comparable to that for displacing [125I]BH-NPY binding. NPY(13-36) was about 500 and 300 times less effective than porcine NPY in increasing [Ca2+]i and in displacing [125I]BH-NPY binding, respectively, showing that the NPY receptor in cultured vascular smooth muscle cells is of the Y1-type.

Animals↗

PubMed1990

[Clinical study on arterio-venous differences in clinical biochemical assay for infants and children at induction of general anesthesia (Enflurane-N2-O-O2). First report: liver function tests].

The arterial blood is often drawn during general anesthesia to measure many biochemical parameters, and, outside the operative period, those parameters are measured mainly in the venous blood. In this way, the A-V differences (the differences between the data from the arterial blood and those from the venous blood) will be found. However, there are few reports about the A-V difference in infants and children. The purpose of this investigation was to compare the arterial blood data with the venous data at the induction of general anesthesia (Enflurane-N2O-O2). In this report, Plasma total bilirubin concentration (by the Michaëlson method), GOT activity, GPT activity (by the Karmen method), gamma-GTP activity (by the gamma-glutamyl CPA substrate method) and pseudocholinesterase activity (by the Shibata-Takahashi method) were measured with both the arterial (from the radial Artery) and the venous samples (from the saphena Magna), in 60 cases of infants and children who had no systemic disease. They were divided into three groups according to age. (Group I: three months old to one year old, Group II: one year old to three years old, and Group III: three years old to six years old.) Each group consisted of 20 patients. The difference and correlation coefficients between arterial and venous measurements were analysed with the paired t-test and correlation analysis Fs = [r2(n-2)/(1-r2)]1/2. Additionally, the data was analysed with a one dimensional analysis for all Groups. In the results, the A-V difference was so small that the conclusion was reached that in these liver function tests there would be no problem in regarding arterial measurements as venous measurements.

Alanine Transaminase↗

PubMed1990

Effects of H+ and HCO3- secretion on mucus gel pH in isolated antral mucosa of bullfrog stomach.

To study the mechanism of self-protection of the gastric surface epithelium, we measured the pH gradient of the mucus gel layer in the isolated bullfrog antral mucosa with pH-sensitive microelectrodes in the Ussing chamber preparation. Under the control condition of 15mM HCO3- and 1.5% CO2 serosal perfusion, the pH on the interface between luminal solution and mucus gel layer (pHLMI) was 6.04 +/- 0.12 (n = 7), and the pH on the interface between the mucus gel layer and epithelial cell (pHMEI) was 5.69 +/- 0.13 (n = 7). When gastric acid secretion was stimulated by histamine (10(-4) M), the pHLMI became 5.43 +/- 0.12 (n = 4) and the pHMEI 4.40 +/- 0.18 (n = 4). Inhibition of acid secretion by cimetidine (10(-4) M) raised the pHLMI to 6.51 +/- 0.07 (n = 7) and the pHMEI to 6.23 +/- 0.08 (n = 7). Omeprazole (10(-4) M) also raised the pHLMI and the pHMEI to 6.78 +/- 0.13 (n = 7) and 6.56 +/- 0.13 (n = 7), respectively. These data suggested that the H+ ions secreted from the oxyntic cells were able to diffuse to the lateral side within the mucus gel layer, affecting the local pH just above the surface epithelial cells. Under high serosal HCO3- condition (45mM HCO3- and 1.5% CO2 in serosal side), the pHLMI and the pHMEI were elevated to 7.22 +/- 0.10 (n = 7) and 6.92 +/- 0.10 (n = 7), respectively. This result suggested that HCO3- secretion, which was served to neutralize the invading acid, depended upon the supply of HCO3- from the serosal medium. Thus, the serosal HCO3- would be working not only in the acid-protection, but also in the maintenance of pH gradient across the mucus gel layer.

Acid-Base Equilibrium↗

PubMed1990

[Annual changes in isolation of MRSA in our department and chemotherapeutic effect of antibiotics including minocycline against postoperative infections of methicillin-resistant S. aureus].

Assessment has been made, using MIC values and coagulase types, of 214 strains of Staphylococcus aureus isolated from the lesions of inpatients at the First Surgical Department, Hiroshima University, from 1983 to 1988. The obtained results are summarized below: 1. Frequency of MRSA among all the strains of S. aureus during a period from 1983 to 1987 was higher than 50%. 2. Highly methicillin-resistant strains (MIC of methicillin greater than 100 micrograms/ml) emerged in 1984 and thereafter, showed a trend of increase through 1987. 3. The highly methicillin-resistant strains are of coagulase II type strain and they are considered to be inhospital epidemic strains. 4. Both ofloxacin and minocycline (MINO) showed good activities against highly methicillin-resistant strains, but many resistant strains were resistant to beta-lactam and aminoglycoside agents. Based on the above basic assessment, chemotherapies mainly using MINO were performed on cases of MRSA infections experienced at the First Surgical Department, Hiroshima University in a period from July, 1987, to November, 1988, and the following results were obtained. 1. Drugs used were: single MINO in 2 cases; MINO+imipenem/cilastatin (IPM/CS) in 4 cases; MINO+IPM/CS+tobramycin in 1 case; MINO+cefmetazole (CMZ) in 1 cases; and MINO+fosfomycin+CMZ (changed to MINO+Amikacin) in 1 case, a total of 9 cases. Clinical result showed remarkable effectiveness of these therapies in 3 cases with some degrees of effectiveness in 6 cases, thus the therapies were all effective or better. 2. No particular abnormality was observed in subjective or objective symptoms or clinical laboratory tests, judged from values obtained before and after administration of MINO. The above results agreed with well those of the basic assessment, suggesting the possibility that the chemotherapies mainly using MINO would exhibit effectiveness on MRSA infections.

Adult↗

PubMed1990

Sociomedical factors affecting participation in screening program on cerebro- and cardio- vascular disease.

In 1984 the Public Health Bureau of Nagoya City began a new health check-up program to encourage citizens aged 40 years to have a medical examination. The rate of participation was 46.6% greater than that of the previous program; however, at about 16%, it was still low. From the survey in Moriyama Ward following results were suggested. Housewives and female part-time workers who had not had a health examination during the previous year showed participation rates of 32.7% and 42.4%, respectively. It would seem that the low rate of participation in the health examination program conducted in the metropolitan area by the municipal Public Health Bureau is due to the existence of many medical care facilities, and the fact that 64.6% of men and 52.6% of women had undergone a medical examination in the year preceding the program. Total screening rates became 69.7% in males and 66.0% in females. Participation rates of 32.7% and 42.4% were achieved by unemployed women and by women with part-time employment, respectively, who had no experience of screening in the previous year. Total screening rates were 63.7% for the unemployed women and 82.1% for the part-time women.

Cardiovascular Diseases↗

PubMed1989

Neuropeptide Y-induced intracellular Ca2+ increases in vascular smooth muscle cells.

The effect of neuropeptide Y (NPY) on cytosolic free Ca2+ concentration ([Ca2+]i) was studied in cultured smooth muscle cells from porcine aorta (PASMC) and compared with the effect of bradykinin (BK) and angiotensin II (ATII) on [Ca2+]i. All peptides induced dose-dependent and transient rises in [Ca2+]i which were not blocked by extracellular EGTA, but the NPY response was different from the others' as follows. First, the [Ca2+]i rise induced by NPY was not as rapid as that induced by BK or ATII. Second, pertussis toxin abolished the [Ca2+]i rise induced by NPY, but not by BK or ATII. Third, following initial treatment with BK, PASMC were able to respond to NPY, but not to ATII. Finally, BK and ATII, but not NPY, significantly increased inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) generation. Although NPY attenuated forskolin-induced accumulation of cyclic AMP, forskolin- and 3-isobutyl-1-methyl-xanthine-induced alterations in intracellular cyclic AMP did not affect the NPY-induced [Ca2+]i rise. These results suggest that NPY increases [Ca2+]i by a pertussis toxin-sensitive GTP binding protein-involved mechanism which is not mediated by the intracellular messengers such as Ins(1,4,5)P3 and cyclic AMP.

1-Methyl-3-isobutylxanthine↗

PubMed1989

Antagonistic actions of S-145 on vascular and platelet thromboxane A2 receptors.

We studied the actions of a potent thromboxane A2/prostaglandin in H2 (TP) receptor antagonist, (+/-)-(5Z)-7-[3-endo-[(phenylsulfonyl)amino]bicyclo [2.2.1]hept-2-exo-yl]heptenoic acid (S-145) on vascular and platelet receptors in the pig. S-145 showed almost the same affinity for both receptors in ligand binding studies with [3H]U46619 or [3H]SQ29, 548. The binding affinity of S-145 was 5-8 times higher than that of SQ29,548, a well-characterized TP receptor antagonist. However, S-145 inhibited U46619-induced contractions of pig coronary arteries with an IC50 value 52.5 times lower than that of SQ29,548, and was approximately equipotent with SQ29,548 in inhibiting U46619-induced secondary aggregation of pig platelets. Detailed kinetic studies on [3H]S-145 binding revealed that the apparent discrepancy between the pharmacological potency of S-145 in platelet and vascular systems was not due to tissue selectivity, but its small association constants for both receptors.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1989

[Clinical studies using a highly sensitive radioimmunoassay for mid-region and carboxy terminus of parathyroid hormone in normal, hypo- and hypercalcemic states].

Parathyroid hormone radioimmunoassay (RIA), specific for mid-region of the PTH molecule, has been proven to be extremely useful for the differential diagnosis of abnormal calcium metabolism. Recently, we developed a highly sensitive RIA for PTH, consisting of PTH antiserum (CH9), 125I labelled Tyr42 hPTH (43-68) and synthetic hPTH (1-84) as standard. This RIA cross-reacted with mid-region and carboxyl terminals of PTH. The within-assay and between-assay coefficients of variation were less than 4.6% and less than 8.6%, respectively. The limit of detection was 50pg/ml. The levels of serum calcium, serum phosphate, serum creatinine, Tmpo4/GFR and creatinine clearance (Ccr) in normal healthy volunteers aged 20 to 50 years remained almost constant and showed 9.24 +/- 0.34mg/dl (mean +/- SD, n = 242), 3.34 +/- 0.38mg/dl (n = 242), 0.870 +/- 0.121mg/dl (n = 242), 3.20 +/- 0.54mg/dl GF (n = 189) and 103 +/- 17ml/min (n = 137), respectively. All healthy volunteers (n = 326) had measurements of PTH in the blood. From 20 to 50 years, normal PTH mean was 374 +/- 97pg/ml (+/- SD, n = 237) and ranged from 180-568pg/ml, and from 60 to 80 years it was 471 +/- 133pg/ml (n = 34) and ranged from 205-737pg/ml. Since we found that PTH was markedly elevated above normal when Ccr was below 40ml/min, and PTH was very significantly correlated with the reciprocal of Ccr (r = 0.8996, P less than 0.001) using a multivariate analysis, all of the patients whose Ccr was higher than 40ml/min were selected and examined in the following studies. Serum PTH values completely separated patients with surgically proven primary hyperparathyroidism (1 degree HPT) from malignant associated hypercalcemia (MAH), and patients with idiopathic hypoparathyroidism (IHP) from pseudohypoparathyroidism (PHP), both of which were diagnosed by Ellsworth-Howard test. PTH values in all of the patients with 1 degree HPT (n = 23) were above normal, but those with MAH (n = 6) were below the normal or lower normal range. PTH values in patients with PHP (n = 7) showed above normal, while those with IHP (n = 5) were below the normal range. PTH was normalized in post operative status in all patients after parathyroidectomy (n = 6). These results indicate that this PTH RIA is extremely useful for the differential diagnosis in diseases with calcium abnormalities.

Adolescent↗

PubMed1989

[Effect of cyproterone acetate on aromatase activity in cultured human genital skin fibroblasts: intracellular control of aromatase activity].

Cyproterone acetate(CA), a well-known competitive antiandrogen, has been used for the treatment of precocious puberty, prostatic adenocarcinoma, hirsutism and hypersexuality. However, there have been some reports of troublesome gynecomastia developing during the use of this drug. It was, therefore, of interest to investigate the effect of CA on peripheral aromatization, since it is the major source of circulating estrogens in men. Our recent studies of aromatase activity in human skin fibroblasts demonstrated that the skin is an important site of extraglandular aromatase activity in men and suggested that these cells might provide a valuable new system in which to study the enzyme. Estrogen formation was assayed by the [3H]H2O technique, after 3h incubation of the cells with androstenedione. The initial experiment was designed to test the effect of CA (10(-8) to 10(-5) M) on baseline aromatase activity during a 12h preincubation in the presence of fetal bovine serum (FBS). Baseline aromatase activity was not affected by the presence of CA, whereas medroxyprogesterone acetate, a similar synthetic progestogen, induced a 2-fold stimulation of aromatase activity at a concentration of 10(-5) M. In cells preincubated with dexamethasone (DEX) in the presence of FBS, aromatase activity was stimulated markedly. When the cells were preincubated in the medium containing FBS with DEX (2.5 X 10(-7) M) in the presence of CA (10(-7) to 10(-4) M), DEX-stimulated levels of aromatase activity were inhibited by CA in a dose-dependent fashion. A competitive binding assay using [3H]DEX, showed that CA was able to compete with DEX for glucocorticoid receptor and the relative binding affinity of CA was approximately 50 times less than DEX. This suggested that the inhibitory effect of CA was due to competition with DEX for receptor binding. Aromatase activity was also stimulated by (Bu)2cAMP (1mM) in the absence of FBS. The stimulatory effect of (Bu)2 cAMP was maximal after 12-24h of preincubation, and this level was maintained for 60h. Similar to the DEX stimulation, stimulation of aromatase activity by (Bu)2cAMP required both RNA and protein synthesis, since the stimulatory effect of (Bu)2cAMP was abolished by co-preincubation with cycloheximide or actinomycin D. When CA was present during either the 12h preincubation or assay incubation, no difference was found in the (Bu)2cAMP-stimulated levels of aromatase activity. On the other hand, the non-aromatizable androgen dihydrotestosterone (DHT) (10(-8) to 10(-6) M) inhibited the stimulation of aromatase activity by (Bu)2cAMP in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 400 WORDS)

Androgen Antagonists↗