ADCK3 mutations with epilepsy, stroke-like episodes and ataxia: a POLG mimic?

BACKGROUND AND PURPOSE: Defects of coenzyme Q10 (CoQ10) metabolism cause a variety of disorders ranging from isolated myopathy to multisystem involvement. ADCK3 is one of several genes associated with CoQ10 deficiency that presents with progressive cerebellar ataxia, epilepsy, migraine and psychiatric disorders. Diagnosis is challenging due to the wide clinical spectrum and overlap with other mitochondrial disorders. METHODS: A detailed description of three new patients and one previously reported patient from three Norwegian families with novel and known ADCK3 mutations is provided focusing on the epileptic semiology and response to treatment. Mutations were identified by whole exome sequencing and in two measurement of skeletal muscle CoQ10 was performed. RESULTS: All four patients presented with childhood-onset epilepsy and progressive cerebellar ataxia. Three patients had epilepsia partialis continua and stroke-like episodes affecting the posterior brain. Electroencephalography showed focal epileptic activity in the occipital and temporal lobes. Genetic investigation revealed ADCK3 mutations in all patients including a novel change in exon 15: c.T1732G, p.F578V. There was no apparent genotype-phenotype correlation. CONCLUSION: ADCK3 mutations can cause a combination of progressive ataxia and acute epileptic encephalopathy with stroke-like episodes. The clinical, radiological and electrophysiological features of this disorder mimic the phenotype of polymerase gamma (POLG) related encephalopathy and it is therefore suggested that ADCK3 mutations be considered in the differential diagnosis of mitochondrial encephalopathy with POLG-like features.

Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism.

OBJECTIVES: Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and elevated risk of cardiovascular disease (CVD). In inflammatory conditions, interferon-γ (IFN-γ) activity is enhanced and a decreased circulating concentration of vitamin B6 is often observed. Such changes in IFN-γ activity or vitamin B6 levels have been associated with increased incidence of CVD. The aim of the study was to investigate systemic markers of IFN-γ-mediated immune activation, such as neopterin, the kynurenine-to-tryptophan ratio (KTR) and kynurenine pathway metabolites, as well as B6 vitamers in patients with PHPT. DESIGN/SUBJECTS: A total of 57 patients with PHPT and a control group of 20 healthy blood donors were included in this study. PHPT patients who responded positively to parathyroidectomy were followed for 6 months. Forty-three patients participated in the longitudinal study in which blood samples were taken at inclusion and 1, 3 and 6 months after surgery. RESULTS: Plasma concentrations of the B6 vitamers pyridoxal 5'-phosphate (PLP) (P = 0.007) and pyridoxal (P = 0.013) were significantly lower in the patient group compared to healthy control subjects. An increase in the KTR indicated that the kynurenine pathway of tryptophan metabolism was altered in PHPT patients (P = 0.015). During the initial 6 months after surgery, levels of PLP (P < 0.001) and anthranilic acid (P < 0.001) increased significantly, whereas neopterin decreased (P = 0.018). CONCLUSIONS: The results of this study demonstrate altered levels of vitamin B6 and the KTR in PHPT patients, both of which may reflect cellular immune activation. These abnormalities should be considered in relation to the increased risk of CVD previously observed in patients with PHPT.

Intracellular Complement Component 3 Attenuated Ischemia-Reperfusion Injury in the Isolated Buffer-Perfused Mouse Heart and Is Associated With Improved Metabolic Homeostasis.

The innate immune system is rapidly activated during myocardial infarction and blockade of extracellular complement system reduces infarct size. Intracellular complement, however, appears to be closely linked to metabolic pathways and its role in ischemia-reperfusion injury is unknown and may be different from complement activation in the circulation. The purpose of the present study was to investigate the role of intracellular complement in isolated, retrogradely buffer-perfused hearts and cardiac cells from adult male wild type mice (WT) and from adult male mice with knockout of complement component 3 (C3KO). Main findings: (i) Intracellular C3 protein was expressed in isolated cardiomyocytes and in whole hearts, (ii) after ischemia-reperfusion injury, C3KO hearts had larger infarct size (32 ± 9% in C3KO vs. 22 ± 7% in WT; p=0.008) and impaired post-ischemic relaxation compared to WT hearts, (iii) C3KO cardiomyocytes had lower basal oxidative respiration compared to WT cardiomyocytes, (iv) blocking mTOR decreased Akt phosphorylation in WT, but not in C3KO cardiomyocytes, (v) after ischemia, WT hearts had higher levels of ATP, but lower levels of both reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+, respectively) compared to C3KO hearts. Conclusion: intracellular C3 protected the heart against ischemia-reperfusion injury, possibly due to its role in metabolic pathways important for energy production and cell survival.

Prognostic significance of Ki-67 labeling index after short-term presurgical tamoxifen in women with ER-positive breast cancer.

BACKGROUND: Studies have shown that Ki-67 response after short-term neoadjuvant aromatase inhibitors may predict recurrence in postmenopausal breast cancer, whereas its prognostic effect in premenopausal women is unknown. PATIENTS AND METHODS: We compared the prognostic and predictive value of baseline and post-treatment Ki-67 in 120 pre- and postmenopausal women with early-stage estrogen receptor-positive breast cancer who participated in a 4-week presurgical trial of tamoxifen. RESULTS: After 7.2 years of follow-up, women with post-treatment Ki-67 in the second (14%-19%), third (20%-29%) and top (≥30%) quartiles had a recurrence hazard ratio of 2.92 [95% confidence interval (CI) 0.95-8.96], 4.37 (1.56-12.25) and 6.05 (2.07-17.65), respectively, as compared with those in the bottom quartile (<14%) (P-trend = 0.001). The risk of invasive disease recurrence was 2.2% (95% CI 0.9-5.0) per point increase in baseline Ki-67 (P-trend = 0.076) and 5.0% (95% CI 2.3-7.7) per point increase in post-tamoxifen Ki-67 (P-trend < 0.001). The risk of death was 5.5 (95% CI 1.26-23.16) times higher in patients with post-drug Ki-67 ≥20% than in those with Ki-67 <20% (P-trend = 0.006). CONCLUSIONS: Ki-67 response after short-term neoadjuvant tamoxifen is a good predictor of recurrence-free survival and overall survival, further supporting its use as surrogate biomarker to personalize adjuvant treatment and to screen novel drugs cost-effectively.

Molecular genetic analysis of an endotoxin nonresponder mutant cell line: a point mutation in a conserved region of MD-2 abolishes endotoxin-induced signaling.

Somatic cell mutagenesis is a powerful tool for characterizing receptor systems. We reported previously two complementation groups of mutant cell lines derived from CD14-transfected Chinese hamster ovary--K1 fibroblasts defective in responses to bacterial endotoxin. Both classes of mutants expressed a normal gene product for Toll-like receptor (TLR)4, and fully responded to stimulation by tumor necrosis factor (TNF)-alpha or interleukin (IL)-1 beta. We identified the lesion in one of the complementation groups in the gene for MD-2, a putative TLR4 coreceptor. The nonresponder phenotype of this mutant was reversed by transfection with MD-2. Cloning of MD-2 from the nonresponder cell line revealed a point mutation in a highly conserved region resulting in a C95Y amino acid exchange. Both forms of MD-2 colocalized with TLR4 on the cell surface after transfection, but only the wild-type cDNA reverted the lipopolysaccharide (LPS) nonresponder phenotype. Furthermore, soluble MD-2, but not soluble MD-2(C95Y), functioned to enable LPS responses in cells that expressed TLR4. Thus, MD-2 is a required component of the LPS signaling complex and can function as a soluble receptor for cells that do not otherwise express it. We hypothesize that MD-2 conformationally affects the extracellular domain of TLR4, perhaps resulting in a change in affinity for LPS or functioning as a portion of the true ligand for TLR4.

Nuclear receptor co-activators and HER-2/neu are upregulated in breast cancer patients during neo-adjuvant treatment with aromatase inhibitors.

BACKGROUND: Acquired resistance to endocrine therapy in breast cancer is poorly understood. Characterisation of the molecular response to aromatase inhibitors in breast cancer tissue may provide important information regarding development of oestrogen hypersensitivity. METHODS: We examined the expression levels of nuclear receptor co-regulators, the orphan nuclear receptor liver receptor homologue-1 and HER-2/neu growth factor receptor using real-time RT-PCR before and after 13-16 weeks of primary medical treatment with the aromatase inhibitors anastrozole or letrozole. RESULTS: mRNA expression of the steroid receptor co-activator 1 (SRC-1) and peroxisome-proliferator-activated receptor gamma co-activator-1alpha (PGC-1alpha) was correlated (P=0.002), and both co-activators increased during treatment in the patient group as a whole (P=0.008 and P=0.032, respectively), as well as in the subgroup of patients achieving an objective treatment response (P=0.002 and P=0.006). Although we recorded no significant change in SRC-3/amplified in breast cancer 1 level, the expression correlated positively to the change of SRC-1 (P=0.002). Notably, we recorded an increase in HER-2/neu levels during therapy in the total patient group (18 out of 26; P=0.016), but in particular among responders (15 out of 21; P=0.008). CONCLUSION: Our results show an upregulation of co-activator mRNA and HER-2/neu during treatment with aromatase inhibitors. These mechanisms may represent an early adaption of the breast cancer cells to oestrogen deprivation in vivo.

Effects of CYP2D6 and SULT1A1 genotypes including SULT1A1 gene copy number on tamoxifen metabolism.

BACKGROUND: Tamoxifen is hydroxylated by cytochrome P450 (CYP) 2D6 to the potent metabolites 4-hydroxytamoxifen (4OHtam) and 4-hydroxy-N-demethyltamoxifen (4OHNDtam), which are both conjugated by sulphotransferase (SULT)1A1. Clinical studies indicate that CYP2D6 and SULT1A1 genotypes are predictors for treatment response to tamoxifen. Therefore, we examined the relationship between CYP2D6 genotype, SULT1A1 genotype, SULT1A1 copy number and the pharmacokinetics of tamoxifen. PATIENTS AND METHODS: The serum levels of tamoxifen and metabolites of 151 breast cancer patients were measured by high-pressure liquid chromatography-tandem mass spectrometry. The CYP2D6 and SULT1A1 polymorphisms and SULT1A1 copy number were determined by long PCR, PCR-based restriction fragment length polymorphism, DNA sequencing and fluorescence-based PCR. RESULTS: The levels of 4OHtam, 4OHNDtam and N-demethyltamoxifen were associated with CYP2D6 predicted enzymatic activity (P < 0.05). The SULT1A1 genotype or copy number did not influence the levels of tamoxifen and its metabolites. However, the ratios of N-demethyltamoxifen/tamoxifen and N-dedimethyltamoxifen/N-demethyltamoxifen were related to SULT1A1 genotype. CONCLUSION: CYP2D6 and SULT1A1 genotypes may partly explain the wide inter-individual variations in the serum levels of tamoxifen and its metabolites. We propose that therapeutic drug monitoring should be included in studies linking CYP2D6 and SULT1A1 genotypes to clinical outcome.

Alpha-lactalbumin-rich infant formula fed to healthy term infants in a multicenter study: plasma essential amino acids and gastrointestinal tolerance.

OBJECTIVE: To evaluate the efficacy and safety of an alpha-lactalbumin-enriched formula with a protein profile and total protein concentration closer to human milk (HM) and lower than conventional formulas. SUBJECTS/METHODS: Two hundred and sixteen healthy, term infants,

DHA and ARA addition to infant formula: Current status and future research directions.

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are present in breast milk and play important roles in early infant development. A supply of these fatty acids in infant formula (typically following breast milk as a model with ARA > DHA) is thought to be important since endogenous synthesis is insufficient to maintain tissue levels equivalent to breast-fed infants. Intervention studies assessing the impact of DHA- and ARA-supplemented formulas have resulted in numerous positive developmental outcomes (closer to breast-fed infants) including measures of specific cognition functions, visual acuity, and immune responses. A critical analysis of outcome assessment tools reveals the essentiality of selecting appropriate, focused techniques in order to provide accurate evaluation of DHA- and ARA-supplemented formulas. Future research directions should encompass in-depth assessment of specific cognitive outcomes, immune function, and disease incidence, as well as sources of experimental variability such as the status of fatty acid desaturase polymorphisms.

Tumor necrosis factor-alpha inhibits stem cell factor-induced proliferation of human bone marrow progenitor cells in vitro. Role of p55 and p75 tumor necrosis factor receptors.

Stem cell factor (SCF), a key regulator of hematopoiesis, potently synergizes with a number of hematopoietic growth factors. However, little is known about growth factors capable of inhibiting the actions of SCF. TNF-alpha has been shown to act as a bidirectional regulator of myeloid cell proliferation and differentiation. This study was designed to examine interactions between TNF-alpha and SCF. Here, we demonstrate that TNF-alpha potently and directly inhibits SCF-stimulated proliferation of CD34+ hematopoietic progenitor cells. Furthermore, TNF-alpha blocked all colony formation stimulated by SCF in combination with granulocyte colony-stimulating factor (CSF) or CSF-1. The synergistic effect of SCF observed in combination with GM-CSF or IL-3 was also inhibited by TNF-alpha, resulting in colony numbers similar to those obtained in the absence of SCF. These effects of TNF-alpha were mediated through the p55 TNF receptor, whereas little or no inhibition was signaled through the p75 TNF receptor. Finally, TNF-alpha downregulated c-kit cell-surface expression on CD34+ bone marrow cells, and this was predominantly a p55 TNF receptor-mediated event as well.

Toll-like receptor 4 imparts ligand-specific recognition of bacterial lipopolysaccharide.

Lipopolysaccharide (LPS) is the main inducer of shock and death in Gram-negative sepsis. Recent evidence suggests that LPS-induced signal transduction begins with CD14-mediated activation of 1 or more Toll-like receptors (TLRs). The lipid A analogues lipid IVa and Rhodobacter sphaeroides lipid A (RSLA) exhibit an uncommon species-specific pharmacology. Both compounds inhibit the effects of LPS in human cells but display LPS-mimetic activity in hamster cells. We transfected human TLR4 or human TLR2 into hamster fibroblasts to determine if either of these LPS signal transducers is responsible for the species-specific pharmacology. RSLA and lipid IVa strongly induced NF-kappaB activity and IL-6 release in Chinese hamster ovary fibroblasts expressing CD14 (CHO/CD14), but these compounds antagonized LPS antagonists in CHO/CD14 fibroblasts that overexpressed human TLR4. No such antagonism occurred in cells overexpressing human TLR2. We cloned TLR4 from hamster macrophages and found that human THP-1 cells expressing the hamster TLR4 responded to lipid IVa as an LPS mimetic, as if they were hamster in origin. Hence, cells heterologously overexpressing TLR4 from different species acquired a pharmacological phenotype with respect to recognition of lipid A substructures that corresponded to the species from which the TLR4 transgene originated. These data suggest that TLR4 is the central lipid A-recognition protein in the LPS receptor complex.

Changes in bone and lipid metabolism in postmenopausal women with early breast cancer after terminating 2-year treatment with exemestane: a randomised, placebo-controlled study.

Aromatase inhibitors improve relapse-free survival in early breast cancer, but there is concern about possible detrimental effects on bone mineral density (BMD) and plasma lipids. This paper presents the results of a 2-year study evaluating the effects of exemestane versus placebo on BMD, bone markers, plasma lipids and coagulation factors, including a 1-year follow-up after termination of treatment in 147 patients. During treatment, the mean annual rate of loss of BMD in the lumbar spine was 2.17% in the exemestane group versus 1.84% in the placebo group (n.s.) and 2.72% versus 1.48%, respectively, in the femoral neck (P=0.024). A loss of BMD above that expected in both arms of this study could be due to low vitamin D status (88% of all patients had vitamin D levels <30 ng/ml). The changes observed with exemestane were partially reversed during a 1-year follow-up, with no significant difference between the two arms. Similarly, the moderate decrease in high-density lipoprotein (HDL)-cholesterol was reversed. The bone marker values decreased, although a difference at 6 months of follow-up was still recorded, in particular for the markers of bone synthesis.

Effects of N-hydroxy-N'-aminoguanidine isoquinoline in combination with other inhibitors of ribonucleotide reductase on L1210 cells.

The 1-isoquinolylmethylene derivative of N-hydroxy-N'-aminoguanidine (HAG) is the most potent agent of the recently synthesized series of HAG-derived ribonucleotide reductase inhibitors. To potentiate the effects of the HAG-isoquinoline drug [HAG-1-isoquinolylmethylene tosylate (HAG-IQ)], we combined it with other inhibitors of ribonucleotide reductase. Using mouse leukemia L1210 cell cultures, we tested drug combinations for their cytostatic and cytotoxic properties and for their effects on intracellular ribonucleotide reductase activity and nucleic acid synthesis. Deoxyguanosine or deoxyadenosine combined with HAG-IQ inhibited cell growth in an additive manner; three-drug combinations, HAG-IQ plus either deoxyguanosine/8-aminoguanosine or deoxyadenosine/deoxycoformycin, were strongly synergistic. When Desferal, an iron chelator, was added to these combinations, the four-drug combinations increased inhibition of cell growth and increased cytotoxicity. The intracellular target of these drug combinations in L1210 cells was the ribonucleotide reductase site. The formation of deoxycytidine from [14C]cytidine and incorporation into DNA were markedly inhibited by these drug combinations, while RNA synthesis was unaffected. These data show that the antiproliferative and cytotoxic effects of HAG-IQ, a potent inhibitor by itself, can be further potentiated in combinations with other ribonucleotide reductase inhibitors.

Distribution of tamoxifen and its metabolites in rat and human tissues during steady-state treatment.

A procedure for the extraction of tamoxifen and metabolites from various rat and human tissues was developed and verified. With this method, we determined the drug and metabolite concentrations during one dosing interval in various tissues (brain, fat, liver, heart, lung, kidney, uterus, and testes) of rats given tamoxifen once daily for 3 or 14 days, and in various normal and malignant tissues obtained during surgery or at autopsy from patients with breast cancer treated with tamoxifen. In the rat, the concentrations of tamoxifen and metabolites in most tissues were 8- to 70-fold higher than in serum. The highest levels were observed in lung and liver; substantial amounts were also recovered from kidney and fat. Fluctuations of metabolites and tamoxifen content in most tissues were observed during one dosing interval, corresponding to a ratio of 4:8 between Cmax and Cmin, except in fat and testicular tissues, where the drug concentrations were relatively stable. In addition to tamoxifen, N-desmethyltamoxifen, followed by 4-hydroxytamoxifen, 4-hydroxy-N-desmethyltamoxifen, and N-desdimethyltamoxifen, were abundant in most tissues. In contrast, adipose tissue contained only small amounts of these metabolites. The concentrations of tamoxifen and metabolites found in human normal and malignant tissues confirmed and extended the conclusions made in the experiments with rats. In humans, levels were 10- to 60-fold higher in tissues than in serum, and relatively high concentrations were detected in liver and lung. Additionally, pancreas, pancreatic tumor, and brain metastases from breast cancer and primary breast cancer retained large amounts of drug. Again, the amounts of demethylated and hydroxylated metabolites were high in most tissues, except in fat. Tamoxifen and some metabolites were also present in specimens of skin and bone tissue. In one patient, significant amounts of drugs could be detected in lung, heart, ovary, and intestinal wall 14 months after withdrawal of tamoxifen, demonstrating efficient retention and slow washout of these compounds in human tissue.

Influence of tamoxifen on plasma levels of insulin-like growth factor I and insulin-like growth factor binding protein I in breast cancer patients.

Plasma levels of insulin-like growth factor I (IGF-I) and insulin-like growth factor binding protein I (IGFBP-I) were measured in fasting blood samples obtained from 16 postmenopausal breast cancer patients before and during tamoxifen treatment for 1 to 6 months. Tamoxifen suppressed total plasma IGF-I by a mean of 28.5% (P less than 0.001) but elevated plasma IGFBP-I by a mean value of 78% (P less than 0.001). Changes in plasma levels of growth hormone, insulin, or insulin C-peptide were not observed. These findings suggest that tamoxifen exerts its influence on plasma IGF-I and IGFBP-I by mechanisms other than those known to regulate the plasma levels of these peptides, primarily growth hormone and insulin, respectively. A dual effect suppressing plasma IGF-I and elevating plasma IGFBP-I suggests that tamoxifen may have a significant influence on endocrine and possibly paracrine delivery of IGF-I to breast cancer cells in vivo.

Effects of N-hydroxy-N'-aminoguanidine derivatives on ribonucleotide reductase activity, nucleic acid synthesis, clonogenicity, and cell cycle of L1210 cells.

Derivatives of N-hydroxy-N'-aminoguanidine were recently shown to be efficient inhibitors of mammalian ribonucleotide reductase and cancer cell growth. We investigated the effects of the 1-isoquinolylmethylene and the 2-quinolylmethylene derivatives of N-hydroxy-N'-aminoguanidine on intracellular targets, cell viability, and cell cycle of L1210 mouse leukemia cells. A 2-h exposure of L1210 cells to either drug in the low micromolar concentration range led to inhibition of intracellular ribonucleotide reductase activity and DNA synthesis. After a 24-h incubation in the presence of these drugs, RNA synthesis was also markedly diminished. The clonogenicity of L1210 cells was inhibited after treatment with the drugs for 24 and 48 h, the I50 values being comparable to the drug concentrations required for 50% inhibition of DNA synthesis and cell proliferation. The isoquinoline compound was always more inhibitory to reductase activity, nucleic acid synthesis, and clonogenicity than the quinoline compound. As shown by flow cytometry, the N-hydroxy-N'-aminoguanidine isoquinoline derivative at 0.5-10 microM led to an elevation of G0/G1 cells and a decrease of G2/M and S cells. At 10 microM of the drug this shift remained unchanged over 48 h. L1210 cells treated with 0.5, 1, and 2 microM of the drug overcame the block after 4 to 12 h of exposure and progressed through S- and G2/M-phase in a synchronized manner.

Identification of 4-hydroxy-N-desmethyltamoxifen as a metabolite of tamoxifen in human bile.

The occurrence of tamoxifen metabolites in bile was investigated in a 57-year-old female patient receiving chronic treatment with tamoxifen. In bile treated with beta-glucuronidase, two major peaks were detected using a chromatographic system developed for the quantitation of tamoxifen metabolites in human serum. One sharp peak coeluted with 4-hydroxy-tamoxifen whereas a second broad peak eluted slightly ahead of tamoxifen and was separated from all major serum metabolites. This latter peak was identified as the cis (about 30%) and trans (about 70%) isomers of 4-hydroxy-N-desmethyltamoxifen. The identification was based on (a) coelution with authentic standard on reversed-phase chromatography and formation of fluorescent material after photoactivation, (b) a molecular ion (M + 1)+ of 374 m/z as determined with liquid chromatography-mass spectrometry, and (c) a fragmentogram identical to that of the authentic standard, as obtained by gas chromatography-mass spectrometry.

Distribution of 4-hydroxy-N-desmethyltamoxifen and other tamoxifen metabolites in human biological fluids during tamoxifen treatment.

Several metabolites of tamoxifen, including 4-hydroxy-N-desmethyltamoxifen (metabolite BX), 4-hydroxytamoxifen (metabolite B), N-desmethyltamoxifen (metabolite X), the primary alcohol (metabolite Y), and N-desdimethyltamoxifen (metabolite Z) were identified and their concentrations determined in fluids and feces from patients receiving chronic tamoxifen treatment. The biological samples investigated were serum, pleural, pericardial and peritoneal effusions, cerebrospinal fluid, saliva, bile, feces, and urine. In serum, tamoxifen itself, and the metabolites X and Z were the prevailing species, but significant amounts of the metabolites Y, B, and BX were also detected. About 3 h after drug intake tamoxifen as well as Y, B, BX, X, and Z showed a peak in serum. This may be explained by efficient metabolism of the metabolite precursor before being distributed to peripheral compartments. Upon drug withdrawal all metabolites showed first-order elimination curves which paralleled that of tamoxifen suggesting that their rate of elimination exceeded that of tamoxifen and that the serum levels are production rate limited. The protein binding of tamoxifen and its major serum metabolites (Y, X, Z) was determined and found to be higher than 98%. Albumin was the predominant carrier for tamoxifen in human plasma. The concentrations of tamoxifen and its metabolites in pleural, pericardial, and peritoneal effusions equalled those detected in serum, corresponding to an effusion/serum ratio between 0.2 and 1. Only trace amounts of tamoxifen and metabolite X were detected in cerebrospinal fluid (CSF/serum ratio less than 0.02). In saliva, concentrations of tamoxifen and X exceeded the amounts of free drug in serum, suggesting active transport or trapping of these compounds in the salivary gland. Bile and urine were rich in the hydroxylated, conjugated metabolites (Y, B, and BX), whereas in feces unconjugated metabolite B and tamoxifen were the predominating species.

Decreased serum concentrations of tamoxifen and its metabolites induced by aminoglutethimide.

The antiestrogen tamoxifen and the aromatase inhibitor aminoglutethimide show similar response rates when used in the endocrine management of advanced breast cancer. However, numerous clinical trials have demonstrated no increase in response rate from treatment with the drug combination of tamoxifen plus aminoglutethimide. We investigated the possibility of a pharmacokinetic interaction between these two drugs in six menopausal woman with breast cancer. All patients were investigated under three different conditions (termed phases A, B, and C). The steady state kinetics of tamoxifen were determined when administered alone (phase A) and after coadministration of aminoglutethimide for 6 weeks (phase B). In phase B, the pharmacokinetics for aminoglutethimide were determined and compared with these parameters after a tamoxifen washout of 6 weeks (phase C). The serum concentration of tamoxifen and most of its metabolites ([trans-1(4-beta-hydroxy-ethoxyphenyl)-1,2-diphenylbut-1-ene], 4-hydroxytamoxifen, 4-hydroxy-N-desmethyltamoxifen, N-desmethyltamoxifen, and N-desdimethyltamoxifen) were markedly reduced following aminoglutethimide administration, corresponding to an increase in tamoxifen clearance from 189-608 ml/min. The amount of most metabolites in serum increased relative to the amount of parent tamoxifen. These data are consistent with induction of tamoxifen metabolism during aminoglutethimide exposure. We found no effect of tamoxifen on aminoglutethimide pharmacokinetics or acetylation. We conclude that this aminoglutethimide-tamoxifen interaction should be taken into account when evaluating the clinical effect of this drug combination relative to monotherapy.

Effects of inhibitors of protein and RNA synthesis on aldosterone-stimulated changes in phospholipid fatty acid metabolism in the toad urinary bladder.

The effects of an inhibitor of RNA synthesis, cordycepin, and an inhibitor of protein synthesis, cycloheximide, on aldosterone-induced changes in lipid metabolism and phospholipid fatty acid composition have been studied in the toad urinary bladder. At the concentrations employed, the inhibitors abolish the hormone-induced increases in total lipid synthesis, phospholipid fatty acid specific activities, and weight percentage of phospholipid long-chain polyunsaturated fatty acids as well as blocking the aldosterone-mediated increase in sodium transport.