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C Eil

Publications and source records attributed to C Eil.

At least 19 recordsLinked to original sources
PubMed1992

Effects of analogs of 1,25(OH)2 vitamin D3 on the proliferation and differentiation of the human chronic myelogenous leukemia cell line, RWLeu-4.

We evaluated the proliferative and differentiative effects of analogs of 1,25(OH)2 vitamin D3 [1,25(OH)2D3] on a chronic myelogenous leukemia cell line, RWLeu-4, which is growth-inhibited and differentiates in response to 1,25(OH)2D3 (ED50 = 3-10 nM). Side-chain-fluorinated analogs were more potent (ED50 = 0.7-2 nM) while most of those with altered saturation of the D ring or side-chain carbon-carbon bonds were equally or less effective than 1,25(OH)2D3. However, the two analogs with either two additional double bonds or an extra double and triple bond in the D ring had greater antiproliferative activity [1,25(OH)2-16,23-diene D3 (ED50 = 2.7 nM) and 1,25(OH)2-16-ene-23-yne D3 (ED50 = 0.7 nM)]. Since the latter of these has been reported to be less potent at mobilizing calcium than 1,25(OH)2D3, it (or a similar compound) may be a candidate for clinical use as an antineoplastic agent.

Antigens, CD↗
PubMed1992

Ketoconazole binds to the human androgen receptor.

Ketoconazole, an imidazole anti-fungal agent, has often produced features of androgen deficiency including decreased libido, gynecomastia, impotence, oligospermia, and decreased testosterone levels, in men being treated for chronic mycotic infections. Based on these potent effects on gonadal function in vivo as well as previous work in vitro demonstrating affinity of ketoconazole for receptor proteins for glucocorticoids and 1,25(OH)2 vitamin D3 and for sex steroid binding globulin (SSBG), the binding of ketoconazole to human androgen receptors (AR) in vitro was also examined. Ketoconazole competition with [3H]methyltrienolone (R1881) for androgen binding sites in dispersed, intact cultured human skin fibroblasts was determined at 22 degrees C. Fifty percent displacement of [3H]R1881 binding to AR was achieved by 6.4 +/- 1.8 (SE) x 10(-5) M ketoconazole. Additional binding studies performed with ketoconazole in the presence of increasing amounts of [3H]R1881 showed that the interaction of ketoconazole with AR was competitive when the data were analyzed by the Scatchard method. It should be noted, however, that the dose of ketoconazole required for 50% occupancy of the androgen receptor is not likely to be achieved in vivo, at least in plasma. Finally, androgen binding studies performed with other imidazoles, such as clotrimazole, miconazole, and fluconozole, revealed that in this class of compounds only ketoconazole appears to interact with the androgen receptor. Ketoconazole appears to be the first example of a non-steroidal compound which binds competitively to both SSBG and multiple steroid hormone receptors, suggesting that the ligand binding sites of these proteins share some features in common.

Cells, Cultured↗
PubMed1991

Hyperphosphatemia in multiple myeloma due to a phosphate-binding immunoglobulin.

Hyperphosphatemia (HP) is usually seen in patients with hypoparathyroidism, renal failure, and tumor lysis. The authors described a patient with HP due to a phosphate-binding immunoglobulin (Ig). An 86-year-old woman had serum phosphate levels as high as 4.75 mmol/l, (normal, 0.77 to 1.45 mmol/l). Serum ionized calcium, blood urea nitrogen (BUN), creatinine, and N-terminal parathyroid hormone (PTH) levels were normal, but serum 1,25-dihydroxyvitamin D level was subnormal at less than 12 pmol/l (normal, 36 to 146 pmol/l). Serum total protein was elevated at 105 g/l (normal, 60 to 80 g/l), and additional studies confirmed a diagnosis of immunoglobulin G (IgG) multiple myeloma. Results of in vitro studies using anti-human IgG antibodies showed that the IgG of the patient bound inorganic phosphate. Several isolated case reports have documented spurious HP due to interference of the paraprotein in the routine serum phosphate assay. In only one patient, however, has actual binding of phosphate to a myeloma protein been documented. The studies of the authors document phosphate binding by an IgG paraprotein and suggest that in this setting HP may be of physiologic significance as evidenced by depressed serum levels of 1,25-dihydroxyvitamin D.

Aged↗
PubMed1990

Mutation in the gene encoding the stimulatory G protein of adenylate cyclase in Albright's hereditary osteodystrophy.

Albright's hereditary osteodystrophy is an autosomal dominant disorder characterized by a short stature, brachydactyly, subcutaneous ossifications, and reduced expression or function of the alpha subunit of the stimulatory G protein (Gs alpha) of adenylate cyclase, which is necessary for the action of parathyroid and other hormones that use cyclic AMP as an intracellular second messenger. We identified a unique Gs alpha protein in erythrocytes from two related patients with Albright's hereditary osteodystrophy and reduced Gs alpha bioactivity. The Gs alpha variant was recognized by a carboxyl terminal-specific Gs alpha antiserum but not by polyclonal antiserums specific for the amino terminus of Gs alpha. To investigate the molecular basis for this structurally abnormal Gs alpha protein, we studied the Gs alpha gene by restriction-endonuclease analysis. DNA from the two patients had an abnormal restriction-fragment pattern when digested with Ncol, which was consistent with loss of an Ncol restriction site in exon 1 of one Gs alpha allele. Amplification of a 260-base-pair region that includes exon 1 of the Gs alpha gene and direct sequencing of the amplified DNA revealed an A-to-G transition at position +1 in one Gs alpha allele from each of the two patients. This mutation converts the initiator ATG (methionine) codon to GTG (valine), blocking initiation of translation at the normal site. Translation of the abnormal Gs alpha messenger RNA would result in the synthesis of a truncated Gs alpha molecule lacking the amino terminus. We conclude that in at least some patients with Albright's hereditary osteodystrophy, the disease is caused by a single-base substitution in the Gs alpha gene and is thus due to an inherited mutation in a human G protein.

Adenylyl Cyclases↗
PubMed1990

Effects of 1 alpha, 25-dihydroxyvitamin D3 on the human chronic myelogenous leukemia cell line RWLeu-4.

The effects of 1 alpha, 25-dihydroxyvitamin D3 (VD3) on proliferation, differentiation, and macromolecular synthesis in the new Philadelphia chromosome-positive chronic myelogenous leukemia cell line, RWLeu-4, were investigated. Binding of [3H]VD3 was saturable, with approximately 2000-3000 sites/cell, and half-maximal binding occurring at 0.21-0.33 nM. Treatment of RWLeu-4 cells with VD3 induced 24R-hydroxylase activity, a marker of vitamin D3 responsiveness in many tissues. Exposure of RWLeu-4 cells to VD3 also inhibited proliferation and DNA synthesis with a 50% effective dose of 3.5-10 nM within 72 h; in addition, protein and RNA synthesis were inhibited by VD3 treatment. Exposure of RWLeu-4 cells to 5 nM VD3 for 72 h caused 50% of the cells to differentiate into macrophage/monocyte type cells as judged by nitroblue tetrazolium staining and adherence to plastic. Progressive expression of cell surface maturation-specific antigens of the monocyte/macrophage lineage was induced by treatment of RWLeu-4 cells with VD3 for 24 to 72 h at doses that inhibited cellular proliferation. c-myc RNA, which is constitutively expressed in RWLeu-4 cells, increased after 0.5 h of treatment with 50 nM VD3 and then rapidly decreased to barely detectable levels after 4 h of treatment. Finally, the in vitro tyrosine kinase activity associated with the p210bcr-abl oncogene product was decreased approximately 50% by VD3 treatment. Because of the presence of a functional receptor-effector system for VD3 and multiple biological responses to the hormone, these cells provide a unique model system with which to probe the specific effects of VD3 on cell growth and differentiation in chronic myelogenous leukemia.

Calcitriol↗
PubMed1990

Ketoconazole reduces elevated serum levels of 1,25-dihydroxyvitamin D in hypercalcemic sarcoidosis.

The antifungal drug ketoconazole, a cytochrome P450 inhibitor, has been shown to inhibit renal 1,25-dihydroxyvitamin D production in vitro and to lower serum 1,25-dihydroxyvitamin D levels in normal subjects and in patients with primary hyperparathyroidism. To assess the usefulness of this drug in the hypercalcemia of sarcoidosis, a condition thought to result from overproduction of 1,25-dihydroxyvitamin D by sarcoid-involved tissues, two men with sarcoidosis, hypercalcemia, and elevated serum levels of 1,25-dihydroxy-vitamin D were given ketoconazole, 600-800 mg per day, for four to six days. Serum 1,25-dihydroxyvitamin D levels were markedly reduced (by approximately 40%) in both patients during ketoconazole administration, but serum calcium was not affected. In both patients, renal function deteriorated during ketoconazole treatment. We conclude that ketoconazole administration can lower the elevated serum 1,25-dihydroxyvitamin D levels in sarcoidosis. However, deterioration of renal function during ketoconazole administration as well as failure of hypercalcemia to be affected during short-term ketoconazole treatment suggest that this drug might not be appropriate for acute treatment of hypercalcemic sarcoidosis.

Adult↗
PubMed1990

The binding properties of pyrethroids to human skin fibroblast androgen receptors and to sex hormone binding globulin.

The pyrethroids are a class of natural and synthetic pesticides which were associated with an epidemic of gynecomastia in Haitian men in 1981. In the present study we tested several pyrethroids for their ability to interact with androgen binding sites in dispersed, intact human genital skin fibroblasts and in human plasma to sex hormone binding globulin (SHBG). All the pyrethroids tested inhibited fibroblast binding of [3H]methyltrienolone (R1881) at 22 degrees C with the following rank order of potency:pyrethrins greater than bioallethrin greater than fenvalerate greater than fenothrin greater than fluvalinate greater than permethrin greater than resmethrin. 50% displacement of [3H]R1881 binding to fibroblast androgen receptors was achieved by 1.5-44 x 10(-5) M concentrations of the competitors, respectively. Previous studies with cimetidine, a known inhibitor of androgen receptor binding, showed 50% competition at a concentration of 1.4 x 10(-4) M in this system. Scatchard analysis of binding experiments performed with increasing concentrations of [3H]R1881 in the presence of the pyrethroids indicated that the binding inhibition was competitive. On the other hand, of the pyrethroids examined only the pyrethrins (50% inhibition) and bioallethrin (43% inhibition) were able to displace [3H]testosterone from SHBG when tested at a concentration of 10(-4) M. These data indicate that a novel class of non-steroidal compounds, the pyrethroids, can interact competitively with human androgen receptors and SHBG. These findings provide a mechanism by which chronic exposure of humans or animals to pesticides containing these compounds may result in disturbances in endocrine effects relating to androgen action.

Fibroblasts↗
PubMed1988

Ketoconazole-induced reduction in serum 1,25-dihydroxyvitamin D and total serum calcium in hypercalcemic patients.

Administration of the antifungal drug ketoconazole reduces serum 1,25-dihydroxyvitamin D (1,25-D) levels in normal subjects. To determine whether a similar effect occurs in hypercalcemic patients, ketoconazole (200 mg every 8 h for 7 days) was given to nine patients with confirmed primary hyperparathyroidism, three patients with probable primary hyperparathyroidism who were awaiting surgery, and three patients with mild hypercalcemia of uncertain etiology who were being followed. Ketoconazole administration led to a significant reduction in mean serum 1,25-D levels in the hypercalcemic patients [basal, 64 +/- 7 (+/- SEM) pg/mL (154 +/- 17 pmol/L) vs. 36 +/- 5 pg/mL (86 +/- 12 pmol/L) after ketoconazole; P less than 0.001]. Serum total calcium fell slightly but significantly [basal, 11.05 +/- 0.17 mg/dL (2.76 +/- 0.04 mmol/L) vs. 10.77 +/- 0.16 (2.69 +/- 0.04 mmol/L) after ketoconazole; P less than 0.02], but the falls in total serum calcium and serum 1,25-D after ketoconazole treatment were not correlated with one another. Ketoconazole administration did not alter serum ionized calcium, 25-hydroxyvitamin D, phosphate, alkaline phosphatase, or PTH concentrations or urinary cAMP excretion. The responses to ketoconazole were similar in all three patient subgroups. We conclude that short term administration of ketoconazole to hypercalcemic patients causes a substantial fall in serum 1,25-D and a small fall in total serum calcium. These effects render ketoconazole a potentially useful agent for investigation of the importance of 1,25-D in patients with hypercalcemic disorders and for their treatment.

Adult↗
PubMed1987

Phospholipase C activity in cultured human skin fibroblasts.

In this paper we report the detection of phospholipase C activity in cultured human skin fibroblasts by a rapid, sensitive method. Sonicates of fibroblasts were incubated with L-3-phosphatidyl-[U-14C]-inositol and the incubation mixture extracted with chloroform/methanol. The solvent components were then separated into 2 phases by the addition of 2 M KCl. Phospholipase C activity, determined from the amount of [14C] in the aqueous phase, agreed well with the enzyme activity assessed by other methods. The optimum pH for the enzyme was 7.0 and the enzyme was found to be dependent on Ca2+ and deoxycholate for optimal activity. The demonstration of phospholipase C activity by this method in cultured skin fibroblasts provides a useful means with which to study, in human tissues, the physiological control of this enzyme and its derangements in disease states in a controlled fashion.

Calcium↗
PubMed1986

Angiotensin-converting enzyme: characteristics in human skin fibroblasts.

Angiotensin-converting enzyme, although most prominent in vascular endothelium, has been identified in numerous tissues. Recent studies have indicated that several hormones, including glucocorticoids and thyroid hormone, may affect the activity of this enzyme. In the present study, angiotensin-converting enzyme was examined in homogenates of cultured human skin fibroblasts. Angiotensin-converting enzyme activity was measured by a radiometric assay using [Glycine-1-14C] Hippuryl-L-histidyl-L-leucine (1.1 mmol/L) as substrate, and was expressed as nmol hippuric acid formed per minute/mg protein. Angiotensin-converting enzyme was identified in all five cell strains tested, and the activity observed was 0.97 +/- 0.18 nmol/min/mg protein (mean +/- SE). The optimum pH was between 6.9 and 7.6, and optimum temperature was 37 degrees C, with loss of activity of 55 degrees C and higher. Buffer strength was optimized at Tris 0.025 mol/L, and 1.0 mol/L NaCl. Activity increased linearly with protein concentration and with time, and the Km = 1.14 mmol/L. The most potent inhibitor of fibroblast ACE was captopril (SQ 14,225) with an IC50 = 10(-10) mol/L; other inhibitors included SQ 20,881, EDTA, and phenanthroline. Competitive substrates included angiotensin-I, substance P, and bradykinin. Four hormones, T3 (10(-9)-10(-7) mol/L), 1,25 (OH)2D3 (10(-8)-10(-7) mol/L), dexamethasone (10(-7)-10(-6) mol/L), and a synthetic androgen, R1881 (10(-8)-10(-7) mol/L) were incubated with cells for 72 hours. In all incubations, there was no significant effect on cellular ACE activity induced by any agent. Angiotensin-converting enzyme activity in serum free media was less than 1% of cell activity and was unaltered by hormone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol↗
PubMed1986

Receptor-positive hereditary resistance to 1,25-dihydroxyvitamin D: chromatography of hormone-receptor complexes on deoxyribonucleic acid-cellulose shows two classes of mutation.

We used cultured skin fibroblasts from patients with hereditary resistance to 1,25-dihydroxyvitamin D [1,25-(OH)2D] and normal hormone binding to soluble extract from cells [i.e. receptor-positive resistance to 1,25-(OH)2D] to characterize DNA binding of the receptor for 1,25-(OH)2D. Occupied receptor was generated by incubating soluble extracts from cells with [3H]1,25-(OH)2D3; occupied receptor was applied to columns of DNA-cellulose and then eluted with linear gradients of KCl. Occupied receptors of cells from other sources eluted as a single peak at 0.20-0.26 M KCl; this elution pattern was independent of tissue (skin, breast cancer, or osteosarcoma) or species (human or rat) of origin of the receptors. With cells from two kindreds in whom there was mildly decreased localization of the hormone-receptor complex to the nucleus in vitro, occupied receptor interacted abnormally with DNA-cellulose (elution at 0.09-0.13 M KCl vs. normal at 0.20-0.26 M KCl); this suggested mutation(s) that affected a DNA-binding domain of the receptor in these two kindreds. With receptor-positive cells from two other kindreds in whom there was unmeasurable hormone localization to the nucleus, the elution pattern of occupied receptors from DNA-cellulose was normal; this suggested mutation(s) which did not affect the same DNA-binding site. We conclude that our demonstration of two distinct elution profiles from DNA-cellulose reflects two independent classes of mutation, either of which can cause receptor-positive resistance to 1,25-(OH)2D.

Animals↗
PubMed1986

Severely deficient binding of 1,25-dihydroxyvitamin D to its receptors in a patient responsive to high doses of this hormone.

A 1.6-yr-old Hispanic boy with sparse hair, muscle weakness, severe growth retardation, and rickets was found to have hypocalcemia, secondary hyperparathyroidism, and high circulating 1,25-dihydroxyvitamin D [1,25-(OH)2D] levels. One year of treatment with a high dose of 1,25-(OH)2D3 (20 micrograms, orally, daily) resulted in marked subjective and radiological improvement; there was a parallel improvement in serum calcium, phosphorus, PTH, alkaline phosphatase, and osteocalcin concentrations. Soluble extracts from cultured skin fibroblasts did not bind [3H]1,25-(OH)2D3 using standard methods. To evaluate the possibility of receptors with abnormally low affinity, we tested for binding with [3H]1,25-(OH)2D3 concentrations higher than those usually used. In one experiment, there was a suggestion of low affinity binding. Hormone receptors with abnormally low affinity for 1,25-(OH)2D may explain this patients resistance to 1,25-(OH)2D. Therapy to maintain extremely high serum 1,25-(OH)2D3 concentrations markedly improved mineral homoeostasis, but did not affect the hair disorder.

Calcitriol↗
PubMed1986

Ketoconazole-induced reduction in serum 1,25-dihydroxyvitamin D.

The antimycotic agent ketoconazole is known to inhibit several cytochrome P450-dependent enzymes involved in the biosynthesis of steroid hormones from cholesterol. Since 1,25-dihydroxyvitamin D is also a sterol synthesized by cytochrome P450-dependent enzymes, we assessed whether ketoconazole would lower serum 1,25-dihydroxyvitamin D levels. In nine normal men, administration of ketoconazole for 1 week in doses of 300-1200 mg/day led to a dose-dependent reduction in serum 1,25-dihydroxyvitamin D levels (r = -0.64; P less than 0.001). At the highest dose taken by each man (1200 mg/day in six, 900 mg/day in one, and 600 mg/day in two), serum levels of 1,25-dihydroxyvitamin D fell significantly compared to baseline [14 +/- 1 (+/- SEM) vs. 39 +/- 3 pg/ml; P less than 0.001), but there was no change in serum levels of 25-hydroxyvitamin D, PTH, calcium, phosphate, or alkaline phosphatase. Ketoconazole may be potentially useful in exploring the pathogenetic role of 1,25-dihydroxyvitamin D in disorders of calcium metabolism and in treatment of patients with hypercalcemic disorders or renal stone disease.

Adolescent↗
PubMed1985

Humoral hypercalcemia in Hodgkin's disease. Association with elevated 1,25-dihydroxycholecalciferol levels and subperiosteal bone resorption.

A 58-year-old man was initially seen with fatigue and weight loss. Laboratory examination detected hypercalcemia, elevated 1,25-dihydroxycholecalciferol levels, low parathyroid hormone (PTH) concentrations, and subperiosteal bone resorption. The patient underwent subtotal parathyroidectomy for presumed hyperparathyroidism, but serum calcium and 1,25-dihydroxycholecalciferol levels remained elevated following surgery. Search for another cause of the hypercalcemia disclosed enlarged para-aortic lymph nodes, biopsy specimens of which demonstrated Hodgkin's disease. After treatment of the patient with two cycles of chemotherapy with mechlorethamine hydrochloride, vincristine sulfate, procarbazine hydrochloride, and prednisone, serum calcium, 1,25-dihydroxycholecalciferol, and PTH levels normalized. We speculate that the humoral hypercalcemia in this patient resulted from tumor production of 1,25-dihydroxycholecalciferol.

Bone Resorption↗