An innovative LC-MS/MS-based method for determining CYP 17 and CYP 19 activity in the adipose tissue of pre- and postmenopausal and ovariectomized women using 13C-labeled steroid substrates

CONTEXT

Does adipose tissue produce steroid hormones like an endocrine organ?

OBJECT

To clarify whether adipose tissue produces sex steroid hormone like an endocrine organ, we estimated several key steroid hormone levels, as well as CYP17 and CYP19 activity, in ovariectomized, pre- and postmenopausal women by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

SUBJECTS AND METHODS

The subjects were 19 premenopausal (n = 12), postmenopausal (n = 4), and ovariectomized women (n = 3) aged 27-68 years. Serum, visceral adipose and sc adipose samples were taken from these subjects and stored at -70°C. The levels of cortisol, cortisone, progesterone (Prog), androstenedione, dehydroepiandrosterone, estrone, estradiol (E2), and T in serum and adipose tissue were estimated simultaneously by LC-MS/MS. CYP17 and CYP19 activity in tissues were assayed with the use of (13)C-labeled steroid precursors and LC-MS/MS-based estimation of the metabolites.

RESULTS

E2 and Prog levels in the sera of postmenopausal or ovariectomized women were less than 10% of those in premenopausal women. No marked variations were seen in other hormones. Estrone, androstenedione, dehydroepiandrosterone, and Prog levels in the visceral and sc tissues of postmenopausal and ovariectomized women were 9-60 times higher than those in serum, whereas E2 and T levels were 3- to 7-fold higher than those in serum, and cortisol and cortisone levels were 20% of those found for serum. CYP17 in adipose tissue was found to have 17-hydroxylase and 20,17-lyase activity, with each catalytic activity being essentially equal. Therefore, CYP17 in adipose tissue is of the testicular/ovarian type but not adrenal type, which has 17-hydroxylase activity dominant. The presence of CYP19 activity in adipose tissue was approximately 3% of CYP17.

CONCLUSION

Our findings suggest that adipose tissue acts as an endocrine organ, with CYP17 and CYP19 activity playing an essential role in sex steroid hormone biosynthesis.

Development of highly sensitive quantification method for testosterone and dihydrotestosterone in human serum and prostate tissue by liquid chromatography-electrospray ionization tandem mass spectrometry

We developed highly sensitive detection of testosterone (T) and 5alpha-dihydrotestosterone (DHT) by liquid chromatography-electrospray ionization tandem mass spectrometry using high proton affinitive derivatization of 17beta-hydroxyl group of T and DHT with picolinic acid, mobile phase consisting of MeCN-MeOH-H(2)O-formic acid and conventional octadecylsilica (ODS) column. Purification of the derivatives was carried out using solid-phase extraction with ODS cartridge. By this method, T and DHT were determined simultaneously with limits of quantification (LOQs) of 1 pg/0.2 ml in serum, and T and DHT with LOQs of 0.5 pg and 1 pg/3mg in prostate tissue, respectively, under acceptable assay performance (intra-assay and inter-assay accuracy and precision). The present method provides reliable and reproducible results for quantification of T and DHT in small volumes of serum and prostate samples for diagnosis in prostatic disorders and male climacteric.

Studies on neurosteroids XXIII. Analysis of tetrahydrocorticosterone isomers in the brain of rats exposed to immobilization using LC-MS

The identification and quantification of tetrahydrocorticosterone isomers (THBs; 3alpha,5alpha-, 3beta,5alpha-, 3alpha,5beta- and 3beta,5beta-THB) in rat brains using liquid chromatography (LC)-mass spectrometry (MS) are described. For the identification, the THBs were converted to the atmospheric pressure chemical ionization (APCI)-active derivatives, i.e., the dinitrobezoyl esters and 2-nitro-4-trifluoromethylphenyl hydrazones, and detected in the negative-ion mode. These derivatives showed 60- and 40-fold higher sensitivities, respectively, than intact steroids measured in the positive-APCI-MS. The derivatized THBs were satisfactorily separated from the others during the reversed-phase LC. The THBs were not detected at all in the brains of the unstressed rats. When the rats were exposed to the immobilization for 20 min, 3alpha,5alpha- and 3beta,5alpha-THB were detected as the major metabolites together with small amounts of 3alpha,5beta- and 3beta,5beta-THB in the male rat brain, while only 3alpha,5alpha-THB was detected in the female rats. Thus, the steroid variety found in the brains was different between the sexes. In the next step, 3alpha,5alpha-THB, a major metabolite found in the brains of the stressed rats, was quantified as its dinitrobezoyl ester. This method was accurate and reproducible, and the limit of quantitation was 1.0 ng/g tissue when a 50 mg tissue sample was used. There was also a sex difference in the brain 3alpha,5alpha-THB level; it was significantly higher in the female rats than in the male rats (P<0.05), although the brain corticosterone level was not higher in the stressed female rats than in the male rats (no statistical difference).

Anion chromatography using on-line recycled eluents

Non-suppressed anion chromatography, using on-line recycled eluents, was investigated. Cations and anions from samples were excluded from the eluents using a mixture of strongly acidic cation-exchange resins and strongly basic anion exchange resins in the eluent reservoir. This exclusion was performed after determination of the anions in the non-suppressed anion chromatography, and the eluents were then recycled on-line. The performance of consecutive determinations was evaluated from the relative standard deviation (RSD) of peak heights and retention times of chloride, bromide, nitrite, nitrate, and sulfate ions, with a concentration of 3 microg ml(-1) each, compared to that of normal anion chromatography. Over 50 consecutive determinations could be achieved with an eluent volume of only 200 ml for a 100 microl sample volume. Almost all the RSD values for retention time, and peak heights of these anions, were smaller than 3%. Over fifty consecutive determinations of chloride, nitrate, and sulfate ions in a river water sample could be achieved with an eluent volume of only 100 ml. All the RSD values for retention time and peak heights of these anions were smaller than 3%. The eluent volume could be decreased to one tenth of that used in normal anion chromatography. The performance of the anion chromatography, using on-line recycled eluents, was the same as that for normal anion chromatography under the same conditions.

Development of a new enzyme-linked immunosorbent assay for the detection of anti-M2 in primary biliary cirrhosis

We developed a new enzyme-linked immunosorbent assay (ELISA) for the detection of antimitochondrial antibody (AMA)-M2 in sera from patients with primary biliary cirrhosis (PBC), using 2-oxo-acid dehydrogenase complex (2-OADC) purified from porcine myocardium as the antigen source. The immunoreactivity was tested in a total of 354 sera, including 63 sera from patients with PBC by our ELISA. In the sera, indirect immunofluorescence for AMA, former ELISA for anti-pyruvate dehydrogenase complex (PDC) and immunoblot assay were performed, respectively. Of the 63 sera from patients with PBC, 51 sera (81.0%) were positive for anti-M2 in the new ELISA. Thirty-eight of the 63 sera (60.3%) were positive for anti-PDC in the former ELISA; the difference was significant between them (P=0.011). None of the 291 control sera from healthy volunteers showed reactivity against 2-OADC in the new ELISA. Moreover, in comparison with the results of immunoblot analysis, sensitivity and specificity in our ELISA to the sera from patients with PBC were 100 and 92.3%, respectively. Our results indicate that the new ELISA for anti-M2 using 2-OADC is simple, rapid and sensitive enough for the detection of AMA specific to PBC.

High sensitivity of a novel ELISA for anti-M2 in primary biliary cirrhosis

The use of an ELISA for the detection of anti-M2, a specific autoantibody in primary biliary cirrhosis (PBC), has been common in Japan. However, there are some problems in the sensitivity of this ELISA, especially in PBC patients showing antimitochondrial antibody (AMA)-negative sera or low AMA titers by immunofluorescence. Recently, a new ELISA for anti-M2 was developed, using porcine heart mitochondrial protein as the antigen. We report here comparative studies of the new and the former anti-M2 ELISAs. Porcine heart mitochondrial protein was prepared and used as the antigen for the new ELISA for anti-M2. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of this protein showed three major M2 antigen proteins. As the second antibody, peroxidase-conjugated anti-human mouse monoclonal IgM, in addition to monoclonal IgG, was included. The sera of 171 PBC patients were examined. As controls, we examined the sera of 167 non-PBC patients and the sera of 115 normal controls. The cut-off index was set at 10 U/ml, based on the results for the normal controls. No sera from the non-PBC patients or the normal controls were positive for anti-M2 by either the new or the former ELISA. However, the positivity rate for anti-M2 in PBC patients with the new ELISA was 78%; in contrast, that with the former ELISA was only 54%; this difference was significant (P = 0.00001). In particular, in 65 patients showing AMA titers of 1:20 or less, the positivity rate with the new ELISA was 51%; in contrast, that with the former ELISA was only 17%. As the sensitivity of the new ELISA is significantly higher than that of the former ELISA, especially for sera from patients showing AMA-negativity or low titers of AMA, the new ELISA is considered to be more effective than the former ELISA for use in anti-M2 screening assays in patients with PBC.

[Successful 5'-DFUR, CDDP and MMC combination therapy and 5'-DFUR and carboplatin combination therapy for a patient with inoperable advanced gastric cancer with peritonitis carcinomatosa]

A 71-year-old man with Borrmann type 3 gastric cancer and peritonitis carcinomatosa was treated with 5'-DFUR 600 mg/body p.o. daily, CDDP 50-80 mg/m2 i.v. on day 1 and MMC 6 mg/m2 i.v. on day 2 after intraperitoneal injection of CDDP and OK-432. The cycle of CDDP and MMC was repeated every 4 or 5 weeks. After 15 cycles of treatment, the primary gastric lesion disappeared and regional lymph node metastasis was reduced. Because of relapsing of the original lesion and concomitant renal dysfunction, a changed regimen of CDDP and Carboplatin was tried. Then the gastric lesion was reduced and lymph node metastasis disappeared. The patient has lived for about 3 years after diagnosis, but his gastric lesion is gradually worsening with duodenal invasion. This case indicates that these combination chemotherapies are quite promising as an effective treatment for advanced gastric cancer and good quality of patient's life.

[Extracranial metastases of brain tumors--a case report and survey of patients with extracranial metastasis sampled from a report on pathological autopsy cases in Japan]

A 36-year-old man who suffered from recurrence of hemangiopericytoma originating in the cerebellar tentorium and multiple extracranial metastasis over 14 years was reported. Analysis of the 104 cases of extracranial metastasis sampled from the Annual of the Pathological Autopsy Cases in Japan revealed that the frequency of extracranial metastasis is 3.8% of all brain tumors. Extracranial metastasis was frequently found in medulloblastoma, glioblastoma multiforme, malignant meningioma and ependymoma. Organs of frequent metastasis were the lung, bone, liver, pleura, and kidney. Bone metastasis was especially frequent in the vertebra.

Deranged metabolism of cyclic nucleotides in liver diseases

To clarify the factor(s) responsible for changes in the plasma cyclic GMP concentration in liver diseases, we measured the plasma levels of cyclic GMP, along with cyclic AMP, in various clinical stages of chronic liver diseases and acute hepatitis. The level of cyclic GMP was found to increase significantly in the early stage of acute hepatitis, in the decompensated stage of liver cirrhosis, and in malignant diseases. In the former two states, it is postulated that decreased hepatic mass is responsible for the changes in the plasma cyclic GMP concentration. The retention rate of indocyanin green (ICGR15) was highly correlated with the plasma cyclic GMP level. The result suggests that the determination of plasma cyclic GMP is useful as an index of the reserve function of the liver in disease states.

Down-regulation of insulin binding by human and rat hepatocytes in primary culture: the possible role of insulin internalization and degradation

Insulin binding and down-regulation were studied in primary cultures of human and rat hepatocytes. Equilibrium binding characteristics were similar in the two species, with a curvilinear Scatchard plot compatible with binding sites of high and low apparent affinities. The dose-response curve for insulin stimulation of glycogen synthesis coincided with the dose-occupancy curve of the low affinity sites; a maximal biological effect was reached at 50% occupancy. Exposure of rat hepatocytes to 2 X 10(-9) M insulin for 24 h produced a 48% decrease in binding capacity due to decreases in both types of binding sites and a 50% decrease in maximal insulin stimulation of glycogen synthesis. After exposure to the same insulin concentration human cells had an 83% decrease in maximum binding capacity, due exclusively to a complete loss of low affinity sites, and a total suppression of insulin stimulation of glycogen synthesis. In both species there was a biphasic relation between degradation and binding: over the range of insulin concentration producing binding mainly to high affinity sites degradation increased slowly as binding increased; with higher insulin concentrations and saturation of high affinity sites degradation increased rapidly as binding to low affinity sites increased. At equal levels of binding, down-regulated cells degraded insulin more rapidly than normal cells. It is concluded that: 1) insulin bound to sites of low apparent affinity is responsible for the hormone's glycogenic effect, 2) down-regulation of human hepatocytes virtually eliminates such binding and the glycogenic response and also increases the rate of degradation of insulin in relation to the amount bound to high affinity sites, 3) human cells are more sensitive than rat cells to down-regulation. It is suggested that in human cells the major effects of exposure to insulin are an inhibition of insulin internalization and an increase in the rate of degradation of that insulin which is internalized; in rat cells the major effects are a decrease in cell surface binding and an increased rate of degradation of internalized insulin.

Effects of alcohol diet from the fetal period on lipid metabolism in rats

The effects of maternal alcohol consumption on lipid metabolism in the litter liver were examined in the rat. Rats reared from their fetal period to adulthood with liquid alcohol diet (fetal alcohol group) did not show any lipid accumulation in the livers. Liver perfusion experiments showed an increased oxygen consumption in the liver to a load of physiological concentration of palmitate. On the contrary, the response of oxygen consumption in fetal control rat livers (reared with non-alcohol liquid diet) to palmitate was found to be depressed. 14CO2 production rate from 14C-palmitate in perfused livers showed a significant increase in fetal alcohol group as compared with controls. No difference in 14C-palmitate incorporation into tissue lipid was found between fetal alcohol and fetal control groups. These data indicate that when rats are treated with alcohol from fetal period they acquire an ability to elevate FFA oxidation in the liver through metabolic adaptation.

Anomalous plasma cyclic AMP responses to glucagon in patients with liver disease

The purpose of the present study is to show anomalies of the plasma cAMP response of patients with hepatic disorders to a single injection of a low dose of glucagon (1 microgram/kg body wt). The response was markedly blunted in patients with liver cirrhosis and potentiated in patients with acute or chronic hepatitis. This glucagon test is, therefore, promising for development as a simple diagnostic means without undertaking liver biopsy to distinguish cirrhosis from chronic hepatitis.

Role of ketone bodies in nonshivering thermogenesis in cold-acclimated rats

The role of ketone bodies (KB) in nonshivering thermogenesis was investigated in warm- and cold-acclimated rats with and without norepinephrine (NE) loads. NE-induced calorigenesis, as evidenced by changes in rectal temperature, was highly developed in cold-acclimated rats, but the levels of blood KB and free fatty acids (FFA) remained almost unaltered. In contrast, FFA turnover rate in cold-acclimated rats under NE load was much greater than in warm-acclimated rats. Similarly, turnover rate of beta-hydroxybutyrate estimated from decay curves of the endogenous substrate in functionally eviscerated rats was significantly higher in cold- than warm-acclimated rats. Perfused livers from cold-acclimated rats produced more KB than warm-acclimated ones. No significant effect of NE load was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast, under constant NE infusion the turnover rate in vivo was almost double that of the perfused liver. These results indicate that KB are an energy source as important as FFA in nonshivering thermogenesis. It may be further surmised that increased KB production in vivo, particularly in the cold-acclimated state, is affected by factor(s) other than NE.

Effects of norepinephrine on uptake and oxidation of plasma free fatty acids in cold-acclimated rats

In order to know the mode of action of norepinephrine in enhanced utilization of plasma free fatty acids (FFA) in cold acclimation, albumin-bound 14C-palmitate was infused intravenously at a constant rate into cold- and warm-acclimated rats under pentobarbital anesthesia with and without norepinephrine infusion. Rectal temperature, CO2 output and plasma FFA, from which the rates of FFA uptake and oxidation were calculated, were determined simultaneously. Similar fractions, that is, 7 and 5% of the total uptake of plasma FFA by the tissue were immediately oxidized in both cold- and warm-acclimated rats, respectively. Norepinephrine infusion caused a significant increase in all the parameters examined. In addition, during hormone infusion the percentage of FFA uptake oxidized was elevated from 22% in control to 50% in cold-acclimated rats. This increment was accompanied with greater increases in rectal temperature and CO2 output. Similarly, in functionally eviscerated cold-acclimated rats, norepinephrine induced a greater increase in the percentage of FFA uptake oxidized than in eviscerated controls. These results indicate that although the FFA uptake was increased simultaneously norepinephrine infusion casued a more marked acceleration of the oxidation of plasma FFA in the cold-acclimated rats than in control rats.

[The role of ketone bodies in nonshivering thermogenesis in cold-adapted rats (author's transl)]

In spite of the ill fame of useless products of metabolism that only accumulate in the blood under abnormal conditions, ketone bodies (KB) have now regained the fame as an important fuel of respiration for the brain and muscles in prolonged starvation in humans and other animals. In cold-adapted animals, ketosis has been well documented, but little is known about the physiological role of KB in cold adaptation. In this study, role of KB in nonshivering thermogenesis was investigated in warm- and cold-adapted rats with or without norepinephrine (NE) loads, a decisive lipid metabolizing hormone in cold adaptation. First, levels of blood KB and plasma free fatty acid (FFA) and FFA turnover rate were examined along with rectal temperature under continuous infusions of various doses of NE. Good dose-response relationship of rectal temperature was obtained with increasing doses of NE in cold-adapted rats, but not in warm-adapted ones. The levels of blood KB and plasma FFA in cold-adapted rats remained almost unaltered during the observation period of 30 minutes. Infusion of NE, however, greatly enhanced FFA turnover rate in cold-adapted rats as compared with controls. Next, fractional turnover rate and half-life of beta-OH-butyrate were obtained from decay curves of endogenous beta-OH-butyrate, using functionally eviscerated rats in which no KB were produced. Calculated turnover rate of KB was also found significantly increased in cold-adapted rats. Finally, the effect of NE on the production of KB was examined using the liver in situ perfusion technique of Mortimore with minor modifications. Viability of the liver preparation was guaranteed by sufficiently high rates of bile production as well as oxygen consumption. The production rate of KB in the preparation under palmitate loads of physiological medium concentration was significantly higher in cold-adapted rats than in warm-adapted controls. However, no significant effect of NE loaded simultaneously was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast NE infusion the turnover rate in vivo was almost doubled that of the perfused liver. All these results indicate KB are used as an important energy source with the significancy of FFA in nonshivering thermogenesis. Moreover, it may be surmised that production of KB in vivo, particulary in the cold-adapted state, is effected by other unknown factors than NE.

[Effect of acute cold exposure on blood composition in rats treated with 6-Hydroxydopamine (author's transl)]

Rats injected with 6-hydroxydopamine (6-OHDA) into the lateral ventricle showed greater elevation in plasma FFA and beta-hydroxybutyrate and significant decrease in blood sugar and lactate following acute cold exposure at -10 degrees C for 2 hours. Changes in the blood composition induced by the cold exposure in rats treated with 6-OHDA intravenously were not different from those observed in control rats. Adrenomedullectomized rats treated with 6-OHDA responded to the cold exposure with rather marked elevation in plasma FFA and beta-hydroxybutyrate. These results were discussed from the view-point of compensatory changes in metabolic regulation in the absence of norepinephrine.

Effects of norepinephrine and thyroxine on the turnover rate of plasma free fatty acids

Effects of norepinephrine infusion on rectal temperature, plasma free fatty acids (FFA) concentration and its turnover rate were studied in rats treated chronically with norepinephrine, thyroxine, or both. Chronic treatments with these hormones resulted in greater increases in rectal temperature and FFA turnover rate in response to norepinephrine as compared with the alterations in controls. Norepinephrine-induced elevation of FFA concentration was smaller in norepinephrine-treated and norepinephrine plus thyroxine-treated rats than in controls, and in thyroxine-treated rats the elevation was similar to that of controls. The regression coefficient of FFA concentration of its turnover rate was greater in all the treated groups than in controls although positive correlations were observed among both variables in the former and the latter. From the results it was inferred that the greater increase in removal of plasma FFA was produced by norepinephrine in parallel with the greater increase in rectal temperature by norepinephrine in rats treated with norepinephrine or thyroxine than in the controls. The effects of norepinephrine infusion were also studied in surgically thryoidectomized rats. In thyroidectomized rats adapted to warm or cold, the smaller increases in rectal temperature and ithe turnover rate of plasma FFA were induced by norepinephrine as compared with the changes in intact rats. The alterations in FFA concentration produced by norepinephrine were less in warm-adapted thyroidectomized rats and greater in cold-acclimated thyroidectomized rats than in respective controls.