Sensitive salivary estradiol assay for monitoring ovarian function

Measurement of steroids in saliva has excited interest because of the numerous potential clinical applications; noninvasive, convenient sampling; and apparently accurate reflection of the concentrations of physiologically active unbound steroid in the circulation. Although assays of saliva for several steroid hormones are available and widely used, assays for salivary estradiol are not, primarily because of methodological limitations. By modifying a commercially available kit for serum estradiol, our laboratory has developed a procedure that is sensitive, highly specific, and reliable for measuring salivary estradiol. Assay sensitivity is 0.5 fmol (0.14 pg; sample concentration 1.3 pmol/L) with a mean interassay CV of 10.8% at low concentrations. Clinical studies showed that values for serum and saliva are highly correlated (P less than 0.001), and demonstrated reliable detection of estradiol peaks during normal ovulatory cycles in serial samples from 15 women. Salivary estradiol peaked at 5.4 (SD 1.9) pmol/L on cycle day 14.4 (SD 3.2), 1.2 (SD 0.8) days before ovulation detected by ultrasound. This assay may be particularly helpful in investigating ovarian function and free estradiol in women at various stages of the reproductive cycle.     

Emergency physician practice and steroid use in the management of acute exacerbations of asthma

This study seeks to determine patterns of emergency physician (EP) practice regarding steroid use in the management of acute asthma attacks in the emergency department (ED), and to compare practices of academic and private practice EPs. Two hundred eight questionnaires were mailed to academic and private practice EPs. The survey requested information regarding the preferred initial route (oral or intravenous) for steroid administration; the initial dose of steroid; the preferred steroid regimen for outpatient management; and whether or not inhaled steroids were routinely prescribed at the time of discharge. The overall response rate was 74%; 91% for the academic EPs and 56% for private practice EPs. Sixty-five percent (99/143) of all EPs used the intravenous route for their initial dose of steroids. A significantly greater percentage of private practice EPs (45/58 or 78%) used intravenous steroids compared with academic EPs (54/95 or 57%; P = .009). A total of 41% (63/153) of EPs used a tapering steroid regime for outpatient therapy; a significantly greater percentage (34/58 or 59%; P = .0006) of private practice EPs used a tapering regimen of steroids compared with academic EPs (29/95 or 31%). A total of 32%(31) academic and 34% (20) private practice EPs prescribed inhaled steroids as part of their routine discharge instructions. Emergency physician practice patterns regarding initial steroid route of administration and dose, and outpatient-dosing regimens are variable. Only a minority of EPs prescribe steroid metered dose inhalers as part of their outpatient management of asthma.     

Systemic corticosteroids in rheumatoid arthritis: to use or not to use?

Systemic corticosteroids(steroids) were initially introduced after the dramatic efficacy in individual patients with rheumatoid arthritis(RA). Since the outcome of steroid therapy in RA turned to be awesome, steroids had been put at the apex of the therapeutic pyramid for a long time. However, most rheumatologists have subscribed steroids for the treatment of early active RA because they can provide rapid and significant clinical response. Moreover, recent several studies have shown that low dose(5 to 10 mg/day) of prednisolone retard joint destruction in a few years. However, the demonstrated negatives(opportunistic infections, osteoporosis, metabolic disorders, atherosclerotic vascular events etc.) of steroids may outweigh these advantages in the longterm clinical course of RA.     

ACTIVITY AND BIOAVAILABILITY OF TOPICAL STEROIDS. IN VIVO / IN VITRO CORRELATIONS FOR THE VASOCONSTRICTOR TEST

The vasoconstrictor assay for topical steroids has been modified and extended so that it may be used to screen for activity and to determine bioavailability. The precision, sensitivity and reproducibility were good for a bioassay. Hydro-philic preparations containing steroid in solution exhibited rank-order relationships between applied concentration and vasoconstriction (Cartesian, semilog, log-probability and log-logistic coordinates). Similar response curves obtained using applied concentration in vivo or amount of steroid released in vitro suggested that vasoconstriction data reflected the amount of steroid penetrating to the capillaries. Pharmacokinetics were non-linear. The assay as developed exceeds the FDA Bioequivalence Requirements and In Vivo Bioavailability Procedures.     

Digoxin does not alter plasma steroid levels in health men

Digoxin has been reported to induce feminizing effects in man. It does not compete for estradiol cytosol receptors in human breast carcinoma cells, however, and has no uterotrophic effect. We therefore investigated whether feminization might be due to digoxin action on plasma concentrations of sex steroids. Six healthy men (31.5 +/- 4 yr old) received therapeutic doses of digoxin for 43 days. We measured plasma concentrations of testosterone, androstenedione, dehydroepiandrosterone, estrone, estradiol, progesterone, 17-hydroxyprogesterone, cortisol, and aldosterone. During 35 days on digoxin levels of these steroids remained in the normal range and there was no change from before-drug values. Digoxin was in the therapeutic range of 1.9 +/- 3 nmol/l throughout. After stimulation by adrenocorticotropic hormone or human choriongonadotropin, the rise in plasma steroids was in the same range as when digoxin was given, as well as 16 wk after it had been discontinued. A normal rise in luteinizing hormone after luteinizing hormone-releasing hormone showed that the hypothalamogonadal feedback was not altered by digoxin. Free testosterone, estradiol, and cortisol concentrations under basal conditions and after stimulation were also the same before and after drug. It is concluded that the estrogen-like activity of digoxin cannot be explained by altered steroid availability from plasma. Feminizing effects attributed to digoxin may be caused by other conditions known to influence sex steroid hormones that are common in patients with heart disease. Our data suggest that digoxin may be the preferred digitalis therapy to avoid feminizing effects.     

Comparison of the CELLEX™ and UVAR‐XTS™ closed‐system extracorporeal photopheresis devices in the treatment of chronic graft‐versus‐host disease

Extracorporeal Photopheresis (ECP) is a cellular immunotherapy frequently used for steroid‐refractory graft‐versus‐host disease (GVHD). Chronic GVHD (cGVHD), response to ECP is associated with survival benefit. The UVAR‐XTS^TM system and the more recently developed CELLEX^TM device (both Therakos^TM) are the mainstay for ECP‐delivery in the UK and US. No comparison of treatment outcomes has been reported. We retrospectively compared cGVHD response and steroid reduction and withdrawal in patients treated exclusively over 12 months with either the XTS (n = 51) or CELLEX (n = 50). Our hypothesis was that there would be no difference in clinical outcome or steroid changes in the 2 matched cohorts. We also compared infection incidence, infection‐related death (IRD), and treatment time. Significant clinical improvement and regular capacity to reduce or cease steroids was encountered in both cohorts; at 6 months of ECP 70% of cutaneous cGvHD patients had partial or complete responses and 85% of patients receiving steroids pre‐ECP had reduced dosage. In the XTS group we unexpectedly encountered both superior steroid reduction (86% dose at least halved vs. 61% for CELLEX, P = 0.01) and withdrawal (15 vs. 5 CELLEX, P = 0.01) and a trend for superior skin disease response in the CELLEX‐treated cohort at 3 months. No inter‐relationship was evident. Halving or greater reduction of steroid dose by 3 or 6 months was associated with reduced risk of IRD in the XTS cohort as was withdrawal at 6 months for the combined cohorts. By 6 months, XTS‐treated patients had experienced fewer antibiotic‐requiring infections (mean 1.9 vs. 2.8, P = 0.025). Origins for the disparities are unclear and warrant investigation.     

Multicenter evaluation of assays for estradiol and progesterone in saliva

Blood samples can be difficult to obtain in studies involving serial sampling, especially in developing countries where there may also be logistic, ethical, and cultural constraints that make frequent blood collection impractical. Assays for steroids in saliva may avoid some of these difficulties. A multicenter study involving laboratories in five countries was carried out to compare the results of assays for salivary estradiol and progesterone performed with centrally provided reagents and assay protocols. Concentrations of salivary steroid as obtained by all but one center were comparable with those reported in the literature. We conclude that assays of hormones in saliva are useful adjuncts to those performed on other body fluids.     

Estrogen levels in childhood determined by an ultrasensitive recombinant cell bioassay.

We hypothesized that estradiol levels are higher in prepubertal girls than in prepubertal boys and that this greater secretion of estradiol might drive the more rapid epiphyseal development and earlier puberty in girls. Since previous estradiol assays have lacked adequate sensitivity to test the hypothesis of higher estradiol levels in girls, we developed a new ultrasensitive assay to measure estrogen levels. The assay uses a strain of Saccharomyces cerevisiae genetically engineered for extreme sensitivity to estrogen. Yeast were transformed with plasmids encoding the human estrogen receptor and an estrogen-responsive promoter fused to the structural gene for beta-galactosidase. Ether extracts of 0.8 ml of serum were incubated with yeast for 8 h and the beta-galactosidase response was used to determine estrogen bioactivity relative to estradiol standards prepared in charcoal-stripped plasma. The assay was highly specific for estradiol with < 3% cross-reactivity with estrone, estriol, or estradiol metabolites. The detection limit was < 0.02 pg/ml estradiol equivalents (100-fold lower than existing assays). Using this assay, we measured estrogen levels in 23 prepubertal boys (9.4 +/- 2.0 yr) and 21 prepubertal girls (7.7 +/- 1.9 [SD] yr). The estrogen level in girls, 0.6 +/- 0.6 pg/ml estradiol equivalents, was significantly greater than the level in boys, 0.08 +/- 0.2 pg/ml estradiol equivalents (P < 0.05). We conclude that the ultrasensitive recombinant cell bioassay for estrogen is approximately 100-fold more sensitive than previous estradiol assays, that estrogen levels are much lower prepubertally, in both sexes, than reported previously, and that prepubertal girls have 8-fold higher estrogen levels than prepubertal boys.     

Sex hormone regulation of in vitro immune response. Estradiol enhances human B cell maturation via inhibition of suppressor T cells in pokeweed mitogen-stimulated cultures

The effects of the main male and female sex hormones, testosterones and estradiol, in pokeweed mitogen (PWM)-stimulated cultures of human blood lymphocytes were studied. We found that the addition of physiological concentrations of estradiol (780-2,600 pmol/liter) to PWM cultures significantly increased the accumulation of immunoglobulin M-containing and -secreting cells detected by immunofluorescence and/or by the reversed protein-A plaque assay. The dose range of estradiol that induced enhanced B cell maturation did not affect the proliferative response. Estradiol displayed the same effect in vitro on lymphocytes from both men and women. Fractionation of lymphocyte subpopulations before culturing revealed that estradiol does not display a direct mitogenic or stimulatory effect of B cells. Instead, estradiol inhibits the suppressive activity of a radio-sensitive (1,000 rad) subset of T lymphocytes bearing Fc-receptors for immunoglobulin G. Nontoxic concentrations fo testosterone did not influence the in vitro B cell maturation. These observations provide a cellular basis for the differences in the immunoreactivities of males and females. The estradiol-induced inhibiton of suppressor T cells might be important for the pathogenesis of various autoimmune disorders.     

Delayed genomic and acute nongenomic action of glucocorticosteroids in seasonal allergic rhinitis

BACKGROUND: Glucocorticosteroids are effective in the treatment of allergic rhinitis, a disease characterized by a variety of symptoms, e.g. rhinorrhea and itching. The time course of symptomatic relief for allergic rhinitis by steroids has not been examined in detail to date, although the onset of steroid action is one of the main discriminations between genomic and nongenomic actions of steroids. We therefore investigated the time course of subjective and objective measures of nasal affection after steroid administration in patients with allergic rhinitis following specific allergen challenge. METHODS: Six female and 18 male volunteers (median age 26 years) with a history of allergic rhinitis but currently free of symptoms were included in this randomized, placebo-controlled, double-blind, three-period crossover study. A single dose of either betamethasone (60 mg), methylprednisolone (400 mg) or placebo was given intravenously, 5 min after intranasal allergen provocation. After 10, 20, 60, 150 and 240 min, nasal itching and nasal obstruction were assessed using a standardized visual analogue scale. In addition, nasal airflow was measured by anterior rhinomanometry. RESULTS: Nasal itching was markedly reduced following either of the two steroids within 10 min after administration of study drug. Itching was depressed by 38% following betamethasone (P<0.05) and by 18% following methylprednisolone (P=0.07) compared with placebo. Nasal airflow and nasal obstruction were not significantly altered by steroids during the first 2 h of the study. However, after 150 min, nasal airflow was 21% rsp. 19% higher after methylprednisolone and betamethasone (P<0.05) compared with placebo. After 240 min, nasal airflow was increased by 20% following betamethasone (P<0.05) and by 19% following methylprednisolone. Nasal obstruction was also beneficially affected by both steroids 150 and 240 min after administration compared with placebo (P<0.05 for both time points following betamethasone). CONCLUSION: This study for the first time shows rapid in vivo effects of external glucocorticosteroids in humans. Itching, a pathophysiologically complex sensation, is favourably influenced by steroids within 10 min, therefore presumably via nongenomic mechanisms. Though no detailed mechanisms can be derived from this study, steroid interaction with receptors in the central nervous system may play an important role in mediating this effect.     

17 beta-Hydroxysteroid dehydrogenase type 2 expression and enzyme activity in the human gastrointestinal tract.

The 17 beta-hydroxysteroid dehydrogenases (17 beta HSDs) play an important role in the regulation of intracellular levels of biologically active sex steroid hormones in various human tissues. To date, eight distinctive 17 beta HSD enzymes have been cloned and characterized in humans. Among these isoenzymes, 17 beta HSD type 2 (17 beta HSD2) catalyses the conversion of testosterone into androstenedione and/or oestradiol into oestrone in various tissues, and it has thus been suggested to be involved in the biological inactivation of these sex steroids. The human gastrointestinal tract and liver are considered as the principle sites of inactivation and metabolism of various forms of orally administered sex steroids. We therefore examined 17 beta HSD2 expression and activity in human adult non-pathological gastrointestinal tract in order to clarify further the biological significance of this enzyme. A total of 80 specimens (40 from males and 40 from females) of normal oesophageal, stomach, duodenal, ileal, colonic and rectal tissues were examined for immunohistochemistry. Altogether, 17 tissue specimens were used for enzyme assay, and eight for RNA analysis. 17 beta HSD2 activity was detected in the stomach, duodenum, ileum, colon and rectum. 17 beta HSD2 mRNA was most abundant in the small intestine. 17 beta HSD2 immunoreactivity was localized almost exclusively to the absorptive epithelium, which may be involved in the inactivation of excessive endogenous and exogenous active sex steroids. Results from the present study thus suggest that the human gastrointestinal tract is an important sex steroid metabolizing organ in humans.     

Glucocorticoid-Binding Proteins in Human Acute Lymphoblastic Leukemic Blast Cells

The first known step in steroid hormone action is the association of the steroid with specific cytoplasmic steroid-binding proteins (SBP). Using a competitive binding assay, we detected, quantified, and partially characterized such a SBP in cytosol from glucocorticoid-sensitive human lymphoblastic leukemic blasts. The affinity of steroids for the SBP was directly related to their known killing potency. For example, steroids without glucocorticoid effect such as androstenedione, etiocholanolone, and tetrahydrocortisol were unable to displace radiolabeled dexamethasone from the SBP in the binding reaction. The dose-response curve for in vitro inhibition of [(3)H]thymidine uptake in leukemic blasts correlated closely with the binding affinity of glucocorticoids to the SBP, providing additional support for an essential physiologic role for SBP in steroid action. SBP activity was either greatly diminished or absent in glucocorticoid-resistant cells. Six patients who intially had SBP in their blasts and were responsive to combinations of drugs including glucocorticoids no longer had SBP activity detectable at a time when they no longer responded to combinations of drugs including glucocorticoids. In vitro [(3)H]thymidine uptake was not inhibited by steroids in leukemic blast cells lacking SBP activity. Other patients who had received some antileukemic therapy including glucocorticoids and who still had SBP in their leukemic blasts, were still responsive to drug combinations that included glucocorticoids. This appears to be the first study demonstrating glucocorticoid receptors in a human tissue.     

Sex steroid influence on triglyceride metabolism.

Triglyceride metabolism was investigated in groups of fed and fasted rats after 21 days of parenteral estradiol (5 mug daily), progesterone (5 mg daily), or the two steroids in combination. Results were compared with control groups receiving an oil solvent alone. In rats given estradiol separately or combined with progesterone, hypertriglyceridemia was uniformly associated with increased plasma triglyceride entry, estimated with the i.v. Triton WR1339 technique. Progesterone alone had no effect on these parameters. Plasma postheparin lipolytic activity (PHLA), adipose, mammary gland, and protamine-resistant liporotein lipases (LPL) were significantly increased in progesterone-treated rats and significantly decreased in rats receiving estradiol with the exception of mammary gland LPL, which was also increased to a slight extent. The combined regimen reduced plasma PHLA and increased protamine-resistant adipose, and mammary gland LPL activity. Sex steroid treatments had minimal effects on plasma glucose and free fatty acid concentrations, but all increased plasma insulin significantly. Hyperinsulinemia did not parallel changes in body weight or other measured parameters. Linear regression analyses revealed that plasma triglyceride concentrations in all fed, treated rats correlated significantly with triglyceride entry but not very uniformly with plasma or tissue LPL activity. We conclude that estradiol, unlike progesterone, has substantial lipemic effects in the rat which relate best to triglyceride entry. Hyperinsulinemia, changes in body weight, plasma PHLA, and tissue LPL activities did not consistently predict the influence of sex steroid treatment on plasma triglyceride concentrations.     

Low dose continuous combined hormone replacement therapy: early and late postmenopausal effect on endometrium.

We investigated endometrial response to low (25 microg through the skin estradiol plus 700 microg norethindrone) and standard dose (2 mg oral estradiol plus 1 mg norethindrone acetate or 700 microg norethindrone) continuous combined therapy in postmenopausal women with time and bone mineral density response. Endometrial thickness was distributed logarithmically, with the means after use of 25 microg estradiol (4.3 mm) and 2 mg estradiol (3.8 mm) being similar. Subjects studied 15.4 +/- 7.0 months apart showed a difference of endometrial thickness of -0.55 +/- 1.3 mm. Neither pretreatment bone mineral density nor change correlated with endometrial thickness. Age, estrogen dose, bone mineral density, weight, and time on treatment do not relate to endometrial thickness. A commonly regarded cutoff point for biopsy, an endometrial thickness of 8 mm, is about 1 SD greater than the mean.     

Sex differences in steroid modulation of ethanol withdrawal in male and female rats

We investigated the actions of the neuroactive steroid, pregnanolone [corrected] and the ovarian steroid, 17beta-estradiol, on seizure expression during two time points of ethanol withdrawal (EW). Both steroids can exert rapid, nongenomic actions on the brain that include modulation of seizure activity. Because their basal levels differ in adult males and females and a major symptom of EW is increased seizure risk, we wanted to determine whether these steroids were anticonvulsant during EW. Rats were made ethanol-dependent by administration of 6% ethanol in a nutritionally complete liquid diet for 14 days. After removal of the ethanol-containing diet, EW and paired control rats were tested at 1 or 3 days for seizure responses to pentylenetetrazol. Consistent with previous reports, females seemed to have recovered from EW more quickly than males. We observed significant sex differences in responses to the steroids, primarily at 3 days EW. Pregnanolone afforded protection against seizures with larger effects during EW than in control conditions and greater effects in female than male rats. In contrast, effects of estradiol were mixed. Some responses of ovariectomized female rats were similar to intact females, whereas other responses were more similar to males. Our behavioral findings are consistent with observed EW-induced changes in plasma corticosterone levels, showing persistent elevations in male but not female rats. These results support and extend earlier findings suggesting that although the hormonal milieu influences EW, innate differences in brain structure between the sexes also contribute to sex differences in EW.     

The use and toxicity of steroids in the management of patients with brain metastases

GOALS OF WORK: To document the use of steroids and frequency of their side effects in patients with brain metastases. PATIENTS AND METHODS: A survey of oncologists who manage patients with brain metastases was conducted to document steroid prescribing practice in our institution. In addition, a retrospective chart review of 88 patients treated with whole brain radiotherapy (WBRT), identified through the Palliative Radiation Oncology Program database, was conducted for a 6-month period to documents steroid doses prescribed, tapering schedules, and steroid side effects. RESULTS: Ninety percent of physicians responded to the survey. Forty-five percent routinely used dexamethasone 4 mg qid (16 mg/day). The others determined the dose of steroid according to the presence or absence of neurological symptoms. Sixty percent tapered the patient's steroids over the 4 weeks following completion of WBRT. The most common side effects noted by physicians were: increased appetite or weight gain (46%), insomnia (24%), gastro-intestinal symptoms (20%). In the retrospective study, dexamethasone 4 mg qid was prescribed to 52% patients prior and during WBRT. Sixty-six percent of patients were instructed to taper dexamethasone after WBRT, but details were not provided. The most frequently documented steroid-related side effects were: increased appetite (32%), proximal muscle weakness (28%), and insomnia (21%). CONCLUSIONS: There is considerable variation in the prescribing practices even within a single institution, with many patients receiving high dose of steroids for considerable periods of time and developing related side effects. Strategies to reduce the amount and length of steroids may result in improved therapeutic ratio; we are currently accruing onto such a trial.     

肾上腺皮质激素治疗全身型重症肌无力的疗效探讨

目的观察肾上腺皮质激素治疗成人全身型重症肌无力（ＭＧ）的疗效、疗程及副作用。方法对３４例患者用大剂量激素递减法治疗。结果激素治疗有效率１００％。激素起效时间胸腺异常组迟于胸腺正常组（Ｐ＜０．０１），严重全身型迟于轻度全身型（Ｐ＜０．０１）。治疗早期，６名患者一度ＭＧ症状加重，但继续治疗后症状均好转。治疗中仅１例出现轻度消化道溃疡。结论对未能用抗胆碱酯酶药及胸腺切除术得到良好控制的ＭＧ患者，激素可作为第一线药物。治疗须按长期用药、缓慢减量的原则，尤其对胸腺异常的严重全身型患者，以防止症状波动及副作用产生。     

人参皂苷Rb1对β-淀粉样蛋白25-35诱导神经干细胞分化过程中Tau蛋白过度磷酸化的影响

背景：前期研究发现,人参皂苷Rb1和β-淀粉样蛋白25-35可调节神经干细胞分化过程中Tau蛋白的磷酸化水平。蛋白磷酸酯酶2A与Tau蛋白过度磷酸化密切相关。目的：观察β-淀粉样蛋白25-35和人参皂苷Rb1对神经干细胞分化过程中Tau蛋白磷酸化水平和蛋白磷酸酯酶2A活性的影响。方法：分离、培养新生大鼠海马神经干细胞,诱导第3代神经干细胞分化1周后分组：①空白组：不加其他处理因素继续培养36h。②β-淀粉样蛋白组：培养24h后,加入β-淀粉样蛋白25-35继续培养12h。③预处理组：先加入人参皂苷Rb1预处理24h,再加入β-淀粉样蛋白25-35继续培养12h。分别采用免疫荧光细胞化学法和western-blot法检测各组细胞Tau[pS396]、Tau[pS262]表达以及蛋白磷酸酯酶2A活性。结果与结论：正常神经干细胞分化过程中有Tau[pS396]和Tau[pS262]的表达;β-淀粉样蛋白组细胞的Tau[pS396]和Tau[pS262]表达上调,蛋白磷酸酯酶2A活性无明显变化;预处理组Tau[pS396]和Tau[pS262]表达下调且蛋白磷酸酯酶2A活性显著增强。提示正常神经干细胞分化过程中Tau蛋白表达一定程度的磷酸化水平,人参皂苷Rb1可通过提高蛋白磷酸酯酶2A活性来减轻β-淀粉样蛋白25-35诱导的神经干细胞分化过程中Tau蛋白过度磷酸化。     

The influence of steroid hormone metabolites on the in vitro development of erythroid colonies derived from human bone marrow

Certain C19 and C21 steroid metabolites, when incubated with normal human bone marrow cells in culture, increased the number of erythroid colonies in the presence of erythropoietin. Among a number of pairs of C5 epimeric steroids tested, most 5beta (A:B cis) steroids stimulated the growth of both early erythroid progenitor cells (BFU-E) and late erythroid progenitor cells (CFU-E), whereas only a few 5alpha-(A:B trans) steroids stimulated the growth of CFU-E. No 5alpha-compounds of six pairs of steroids studied were found to stimulate BFU-E formation. This structure-activity relationship conforms with that previously observed in studies of steroid induction of ALA-synthase in avian embryo liver cells and hemoglobin synthesis in the cultured avian blastoderm. When human bone marrow cells were preincubated with the steroids for 2 d, followed by incubation with erythropoietin, only the 5 beta-compounds stimulated the growth of BFU-E. Similarly, when addition of steroids was delayed in relation to erythropoietin in the culture, only the 5 beta-derivative of a pair of C5 epimeric compounds displayed an enhancing effect on the growth of BFU-E. This effect required that the steroid addition be made no later than 48 h after initiation of the culture. These data demonstrate that certain natural steroid metabolites significantly stimulate erythropoiesis in normal human bone marrow cells in culture. They also indicate that 5 beta-compounds are more stimulatory than their 5 alpha-epimers, and they suggest that these 5 beta-steroids act preferentially on very primitive erythroid progenitor cells, probably on BFU-E.