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S E Davis

Publications and source records attributed to S E Davis.

At least 55 records · Page 3Linked to original sources
PubMed1980

Potential limitations of recrystallization for the definitive identification of radioactive steroids.

The usefulness of recrystallization in establishing the radiochemical purity of steroids is widely recognized, but the potential limitations of the technique have received little attention. The current study reports the failure of standard recrystallization procedures using methanol/water as the solvent pair to separate contaminating 14C-17-hydroxyprogesterone (17-hydroxy-4-pregnene-3, 20-dione) from 3H- and 14C-labeled 11-deoxycortisol (17,21-dihydroxy-4-pregnene-3,20-dione) despite ten serial crystallizations. The standard criteria of radiochemical purity were met despite gross impurity of the crystals as evidenced by thin layer chromatography. Thus, recrystallization may, under certain conditions, yield misleading results when employed as the only method for identifying radioactive steroids. These observations illustrate the importance of an optimal choice of solvent and crystallization conditions, and emphasize the need for confirmation by derivative formation and chromatography.

17-Hydroxycorticosteroids↗
PubMed1980

Radioimmunoassay data processing with a small programmable calculator.

We have developed three programs for data processing for radioimmunoassays RIA implemented on a small, inexpensive, programmable calculator (Texas Instrument Co., Model 59): 1) The first program performs a weighted logit-log regression for analysis of the RIA standard curve, and provides several descriptive statistics: slope, intercept, ED50 (and their corresponding standard errors), residual variance, and correlation coefficient. This program also provides: dose interpolation for unknowns; an estimate of the precision (percent coefficient of variation) for each result; corrections for variable sample volumes or recoveries; and the mean and standard error of the mean for samples analyzed in replicate. 2) The second program uses the "four parameter logistic model" to describe the dose responses curve and perform dose interpolation. This is the equivalent to the use of the logit-log method, with provision for adjustment for the position of the 0% and 100% response. As such, it is more flexible and versatile than the logit-log method. 3) A third program is used for routine Within-Lab Quality Control: it calculates within-assay and between-assay precision, utilizing an analysis of variance (ANOVA) with a components of variance estimation. These programs incorporate the most important features of programs previously developed in this laboratory for an IBM 370 or a DECsystem-10 computer, and demonstrate the availability of adequate statistical analyses to laboratories without access to large centralized computer facilities.

Analysis of Variance↗
PubMed1980

Rapid metabolic clearance of the catechol estrogen 2-hydroxyestrone.

The plasma metabolic clearance rate (MCRp) of 2-hydroxyestrone was measured in normal young adults by two methods: infusion of unlabeled 2-OHE1 to equilibrium with radioimmunoassay of plasma 2-OHE1 levels, and infusion of [3H]2-OHE1 to equilibrium with measurement of chromatographically purified plasma [3H]2-OHE1. MCR's were 40--70,000 L/day and 15--50,000 L/day, respectively. This is the highest known MCR for a naturally occurring steroid. The only measurable plasma metabolite of [3H]2-OHE1 co-migrated with 2-methoxyestrone. When [3H]2-OHE1 was incubated with blood samples in vitro, [3H] xi-methoxyestrone was rapidly formed. Since this MCR is higher than cardiac output, clearance must occur primarily in the blood compartment, probably largely by the action of erythrocyte catechol-0-methyltransferase.

Adult↗
PubMed1980

Timed 12-hour specimens in outpatient estriol monitoring.

Use of maternal urinary estriol excretion to monitor fetal status is often hampered by the difficulties of obtaining 24-hour specimens. Evidence is presented that timed, 12-hour overnight specimens may be substituted for the 24-hour specimens in certain patient groups. A simple non-refrigerated transport system which facilitates outpatient estriol monitoring is also described.

Ambulatory Care↗
PubMed1979

Dissociation of cortisol and adrenal androgen secretion in patients with secondary adrenal insufficiency.

Plasma cortisol, dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), and androstenedione (delta4-A) were measured by RIA during ACTH infusion in preadrenarchal children with constitutional short stature, normal adults, and patients with secondary adrenal insufficiency resulting from hypothalamic-pituitary disease or corticosteroid therapy. The plasma levels of all four steroids were decreased in patients with secondary adrenal insufficiency compared to normal adults, but the decrease in DHA and DHAS was considerably greater than that in cortisol and delta4-A, resulting in significant decreases in the plasma ratios of DHA to cortisol, DHAS to cortisol, DHA to delta4-A, and DHAS to delta4-A (P less than 0.00001). The decreased DHA and DHAS responses to ACTH persisted in one glucocorticoid-treated patient after glucocorticoid therapy was terminated and the cortisol response to ACTH had normalized. The data suggest that adrenal atrophy due to hypothalamic-pituitary disease or corticosteroid therapy is associated with a greater impairment in the secretion of the delta5 adrenal androgens DHA and DHAS than in the secretion of cortisol and delta4-A, and that the capacity to secrete cortisol and delta4-A recovers more rapidly than the capacity to secrete the delta5 adrenal androgens when corticosteroid therapy is withdrawn.

Adolescent↗
PubMed1975

A simple specific assay for estriol in maternal urine.

In medical centers with many high risk pregnancies, the ability to perform a large number of urinary estriol measurements is required. The analytical procedure should provide simplicity, specificity, and economy. A solid phase radioimmunoassay is presented which utilizes antibody generated against an estriol 16-glucuronide-bovine serum albumin conjugate. The assay allows analysis of the principal component of maternal urinary estriol without hydrolysis or purification, with adequate specificity and the capacity for processing large numbers of samples.

Animals↗
PubMedDate not supplied

A 19 year old with complete androgen insensitivity syndrome and juvenile fibroadenoma of the breast.

We report a case of a 19-year-old female with complete androgen insensitivity syndrome (CAIS) who was diagnosed with a juvenile fibdroadenoma of the breast. The patient presented at age 18 with primary amenorrhea. She had been raised as a female and went through thelarche at age 13 and adrenarche at age 14. She had two sisters and three maternal aunts with androgen insensitivity syndrome. Physical exam revealed that the patient had no cervix, and a pelvic sonogram confirmed that the uterus was absent. Genetic analysis revealed a 46 XY karyotype. Bilateral intra-abdominal testes were noted on ultrasound and subsequently removed. She was placed on synthetic estrogen replacement therapy. Roughly 1 year following orchiectomy, the patient noticed an enlarging mass in her right breast. Physical exam revealed a roughly 5 cm mobile mass in the upper portion of the nipple-areolar complex. Ultrasound showed a solid mass consistent with a fibroadenoma. Because of the size of the lesion and the patient's hormonal make-up, a fine needle aspirate was obtained. Cytopathology showed large cohesive sheets of ductal epithelial cells, scattered histiocytes, numerous bare nuclei, fragments of fibrous tissue and metachromatic stroma. Some of the stroma was noted to be cellular. The tumor was subsequently excised. Microscopically, the lesion had epithelial and stromal hyperplasia consistent with a fibroadenoma. Phyllodes-like qualities of large size, increased stromal cellularity, and intracanalicular growth ("leaf-like projections") were noted; however, the pathologist found that the florid epithelial hyperplasia and the patient's young age were more compatible with a juvenile fibroadenoma. We describe what we believe to be the first report of a patient with CAIS and a fibroadenoma of the breast. The hormonal imbalance typically found in these patients, combined with the fact that most individuals with CAIS receive exogenous estrogen therapy, suggests that there may be a relatively high incidence of fibroadenoma in these patients.

Adult↗