Human pluripotent stem cell-derived cells endogenously expressing follicle-stimulating hormone receptors: modeling the function of an inactivating receptor mutation.

Follicle-stimulating hormone (FSH) is crucial in the development and regulation of reproductive functions. The actions of human FSH and its receptor (FSHR) and mutations therein have mainly been studied using in vivo models, primary cells, cancer cells and cell lines ectopically expressing the FSHR. To allow studies of endogenous FSHR function in vitro, we differentiated FSHR-expressing cells from human pluripotent stem cells. FSH stimulation of the wild-type (WT), but not the inactivating Finnish founder mutant (A189V) receptor, activated the canonical cyclic adenosine monophosphate (cAMP)-dependent signaling pathway and downstream mediators. To investigate protein-protein interaction partners of FSHR at resting state and upon FSH stimulation, we expressed FSHR in HEK293 cells followed by affinity purification mass spectrometry analyses. We found 19 specific high-confidence interacting proteins for WT FSHR and 14 for A189V FSHR, several of which have been linked to infertility. Interestingly, while only WT FSHR interacted with FSH, insulin-like growth factor 1 receptor (IGF1R), for example, interacted with both WT and A189V FSHR upon FSH stimulation. In conclusion, our protocol allows detailed studies of FSH action and disease modeling in human cells endogenously expressing FSHR.

Pubertal induction and transition to adult sex hormone replacement in patients with congenital pituitary or gonadal reproductive hormone deficiency: an Endo-ERN clinical practice guideline.

An Endo-European Reference Network guideline initiative was launched including 16 clinicians experienced in endocrinology, pediatric and adult and 2 patient representatives. The guideline was endorsed by the European Society for Pediatric Endocrinology, the European Society for Endocrinology and the European Academy of Andrology. The aim was to create practice guidelines for clinical assessment and puberty induction in individuals with congenital pituitary or gonadal hormone deficiency. A systematic literature search was conducted, and the evidence was graded according to the Grading of Recommendations, Assessment, Development and Evaluation system. If the evidence was insufficient or lacking, then the conclusions were based on expert opinion. The guideline includes recommendations for puberty induction with oestrogen or testosterone. Publications on the induction of puberty with follicle-stimulation hormone and human chorionic gonadotrophin in hypogonadotropic hypogonadism are reviewed. Specific issues in individuals with Klinefelter syndrome or androgen insensitivity syndrome are considered. The expert panel recommends that pubertal induction or sex hormone replacement to sustain puberty should be cared for by a multidisciplinary team. Children with a known condition should be followed from the age of 8 years for girls and 9 years for boys. Puberty induction should be individualised but considered at 11 years in girls and 12 years in boys. Psychological aspects of puberty and fertility issues are especially important to address in individuals with sex development disorders or congenital pituitary deficiencies. The transition of these young adults highlights the importance of a multidisciplinary approach, to discuss both medical issues and social and psychological issues that arise in the context of these chronic conditions.

Anti-Müllerian hormone and letrozole levels in boys with constitutional delay of growth and puberty treated with letrozole or testosterone.

STUDY QUESTION: Does treatment of constitutional delay of growth and puberty (CDGP) in boys with aromatase inhibitor letrozole (Lz) or conventional low-dose testosterone (T) have differing effects on developing seminiferous epithelium? SUMMARY ANSWER: Anti-Müllerian hormone (AMH) declined similarly in both treatment groups, and the two Sertoli cell-derived markers (AMH and inhibin B (iB)) exhibited differing responses to changes in gonadotrophin milieu. WHAT IS KNOWN ALREADY: Boys with CDGP may benefit from puberty-inducing medication. Peroral Lz activates gonadotrophin secretion, whereas intramuscular low-dose T may transiently suppress gonadotrophins and iB. STUDY DESIGN, SIZE, DURATION: Sera of 28 boys with CDGP who participated in a randomised, controlled, open-label trial at four paediatric centres in Finland between August 2013 and January 2017 were analysed. The patients were randomly assigned to receive either Lz (2.5 mg/day) (n = 15) or T (1 mg/kg/month) (n = 13) for 6 months. PARTICIPANTS/MATERIALS, SETTING, METHODS: The 28 patients were at least 14 years of age, showed first signs of puberty, wanted medical attention for CDGP and were evaluated at 0, 3, 6 and 12 months of visits. AMH levels were measured with an electrochemiluminescence immunoassay and Lz levels with liquid chromatography coupled with tandem mass spectrometry. MAIN RESULTS AND THE ROLE OF CHANCE: AMH levels decreased in both treatment groups during the 12-month follow-up (P < 0.0001). Between 0 and 3 months, the changes in gonadotrophin levels (increase in the Lz group, decrease in the T group) correlated strongly with the changes in levels of iB (FSH vs iB, r = 0.55, P = 0.002; LH vs iB, r = 0.72, P < 0.0001), but not with the changes in AMH (P = NS). At 12 months, AMH levels did not differ between the groups (P = NS). Serum Lz levels (range, 124-1262 nmol/L) were largely explained by the Lz dose per weight (at 3 months r = 0.62, P = 0.01; at 6 months r = 0.52, P = 0.05). Lz levels did not associate with changes in indices of hypothalamic-pituitary-gonadal axis activity or Sertoli cell markers (in all, P = NS). LIMITATIONS, REASONS FOR CAUTION: The original trial was not blinded for practical reasons and included a limited number of participants. WIDER IMPLICATIONS OF THE FINDINGS: In early puberty, treatment-induced gonadotrophin stimulus was unable to counteract the androgen-mediated decrease in AMH, while changes in iB levels were associated with changes in gonadotrophin levels. AMH decreased similarly in both groups during the treatment, reassuring safety of developing seminiferous epithelium in both treatment approaches. Since a fixed dose of Lz induced variable serum Lz levels with a desired puberty-promoting effect in all boys, more research is needed to aim at a minimal efficient dose per weight. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Academy of Finland, the Foundation for Pediatric Research, the Emil Aaltonen Foundation, Sigrid Juselius Foundation and Helsinki University Hospital Research Funds. The authors have nothing to disclose. TRIAL REGISTRATION NUMBER: NCT01797718.

Disorders of sex development: timing of diagnosis and management in a single large tertiary center.

BACKGROUND: We describe the phenotypic spectrum and timing of diagnosis and management in a large series of patients with disorders of sexual development (DSD) treated in a single pediatric tertiary center. METHODS: DSD patients who had visited our tertiary center during the survey period (between 2004 and 2014) were identified based on an ICD-10 inquiry, and their phenotypic and molecular genetic findings were recorded from patient charts. RESULTS: Among the 550 DSD patients, 53.3% had 46,XY DSD; 37.1% had sex chromosome DSD and 9.6% had 46,XX DSD. The most common diagnoses were Turner syndrome (19.8%, diagnosed at the mean age of 4.7 ± 5.5 years), Klinefelter syndrome (14.5%, 6.8 ± 6.2 years) and bilateral cryptorchidism (23.1%). Very few patients with 46,XY DSD (7%) or 46,XX DSD (21%) had molecular genetic diagnosis. The yearly rate of DSD diagnoses remained stable over the survey period. After the release of the Nordic consensus on the management of undescended testes, the age at surgery for bilateral cryptorchidism declined significantly (P < 0.001). CONCLUSIONS: Our results show that (i) Turner syndrome and Klinefelter syndrome, the most frequent single DSD diagnoses, are still diagnosed relatively late; (ii) a temporal shift was observed in the management of bilateral cryptorchidism, which may favorably influence patients' adulthood semen quality and (iii) next-generation sequencing methods are not fully employed in the diagnostics of DSD patients.

New intronic Fibroblast Growth Factor Receptor 1 (FGFR1) mutation leading to disrupted splicing and Kallmann syndrome.

Congenital hypogonadotropic hypogonadism (CHH), which can present with a defective sense of smell (Kallmann syndrome, KS), is a clinically and genetically heterogeneous disorder. Over 31 genes have been associated with CHH, but most of the patients still lack a molecular genetic diagnosis. Some cases may be explained by mutations that disrupt the splicing of already established CHH genes but that are unrecognized either because they are located deep in introns or are not predicted to disrupt splicing. Here we identified a patient with a previously unreported Fibroblast Growth Factor Receptor 1 (FGFR1) mutation, c.1664-9T>G, that leads to the skipping of exon 13 of FGFR1. Notably, the mutation was not predicted to cause a significant alteration in the splicing motif but in vitro analysis confirmed the pathogenicity of the mutation. Our results thus reveal a new splicing-affecting mutation in FGFR1 and suggest that all new sequence variants located close to exon/intron boundaries should be experimentally investigated for pathogenicity, rather than relying solely on computer prediction programs.

Genetic Overlap between Holoprosencephaly and Kallmann Syndrome.

Patients with Kallmann syndrome (KS; congenital hypogonadotropic hypogonadism and decreased/absent sense of smell), septo-optic dysplasia (SOD), or holoprosencephaly (HPE) reportedly have midline defects. In this study, we investigate a genetic overlap between KS, SOD, and HPE. Nineteen subjects (18 males, 1 female) with KS and without mutations in the known KS genes were screened for mutations in SOX2, SHH, SIX3,TGIF1,TDGF1,FOXH1,GLI2, and GLI3. One male carried 2 heterozygous missense changes, one in SIX3 (c.428G>A, p.G143D) and the other in GLI2 (c.2509G>A, p.E837K). Both of these genes have been implicated in the etiology of HPE and neither of these changes were present in 200 control subjects. Other variants found among the subjects were known polymorphisms. KS and HPE may display a genetic overlap. The involvement of genes implicated in the etiology of midline defects in patients with KS warrants further studies.

Mutations that impact the enteropathogenic Escherichia coli Cpx envelope stress response attenuate virulence in Galleria mellonella.

In this paper, we show that the larvae of the greater wax moth, Galleria mellonella, can be used as a model to study enteropathogenic Escherichia coli (EPEC) virulence. G. mellonella larvae are killed after infection with EPEC type strain E2348/69 but not by an attenuated derivative that expresses diminished levels of the major virulence determinants or by a mutant specifically defective in type III secretion (T3S). Infecting EPEC inhabit the larval hemocoel only briefly and then become localized to melanized capsules, where they remain extracellular. Previously, it was shown that mutations affecting the Cpx envelope stress response lead to diminished expression of the bundle-forming pilus (BFP) and the type III secretion system (T3SS). We demonstrate that mutations that activate the Cpx pathway have a dramatic effect on the ability of the bacterium to establish a lethal infection, and this is correlated with an inability to grow in vivo. Infection with all E. coli strains led to increased expression of the antimicrobial peptides (AMPs) gloverin and cecropin, although strain- and AMP-specific differences were observed, suggesting that the G. mellonella host perceives attenuated strains and Cpx mutants in unique manners. Overall, this study shows that G. mellonella is an economical, alternative infection model for the preliminary study of EPEC host-pathogen interactions, and that induction of the Cpx envelope stress response leads to defects in virulence.

Cholesterol metabolism altered and FGF21 levels high after pediatric liver transplantation despite normal serum lipids.

Liver transplantation (LT) predisposes to metabolic derangements and increases the risk for cardiovascular disease. We conducted a national cross-sectional study of all pediatric recipients who underwent LT between 1987 and 2007. We measured serum levels of noncholesterol sterols (surrogate markers of cholesterol synthesis and intestinal absorption) and fibroblast growth factor 21 (FGF21) in 49 patients (74% of survivors) at a median of 10 years posttransplant and in 93 controls matched for age and gender. Although serum cholesterol levels were similar in patients and controls, patients displayed increased whole-body synthesis and decreased intestinal absorption of cholesterol compared with controls (lathosterol to cholesterol ratio 129 ± 55 vs. 96 ± 41, respectively, p < 0.001; campesterol to cholesterol ratio 233 ± 91 vs. 316 ± 107, respectively; p < 0.001). Azathioprine (r =-0.383, p = 0.007) and low-dose methylpredisolone (r =-0.492, p < 0.001) were negatively associated with lathosterol/sitosterol ratio reflecting a favorable effect on cholesterol metabolism. FGF21 levels were higher in patients than in controls (248 pg/mL vs. 77 pg/mL, p < 0.001). In healthy controls, FGF21 was associated with cholesterol metabolism, an association missing in LT recipients. Normal serum lipids are achievable in long-term survivors of pediatric LT, but changes in cholesterol metabolism and increased FGF21 levels may explicate later cardiovascular risk.

Bone mineral density, body composition and bone turnover in patients with congenital hypogonadotropic hypogonadism.

Patients with congenital hypogonadotropic hypogonadism (HH) may have reduced peak bone mass in early adulthood, and increased risk for osteoporosis despite long-term hormonal replacement therapy (HRT). To investigate the relationship between HRT history and measures of bone health in patients with HH, we recruited 33 subjects (24 men, nine women; mean age 39.8 years, range: 24.0-69.1) with congenital HH (Kallmann syndrome or normosmic HH). They underwent clinical examination, were interviewed and medical charts were reviewed. Twenty-six subjects underwent dual-energy X-ray absorptiometry for evaluation of BMD of lumbar spine, hip, femoral neck and whole body; body composition and vertebral morphology were evaluated in 22 and 23 subjects, respectively. Circulating PINP, ICTP and sex hormone levels were measured. HRT history clearly associated to bone health: BMDs of lumbar spine, femoral neck, hip and whole body were lower in subjects (n = 9) who had had long (≥5 years) treatment pauses or low dose testosterone (T) treatment as compared to subjects without such history (n = 17; all p-values < 0.05). In addition, fat mass and body mass index (BMI) were significantly higher in men with deficient treatment history (median fat mass: 37.5 vs. 23.1%, p = 0.005; BMI: 32.6 vs. 25.2 kg/m(2), p < 0.05). Serum PINP correlated with ICTP (r(s) = 0.61; p < 0.005) in men, but these markers correlated neither with circulating T, nor with serum estradiol levels in women. In conclusion, patients with congenital HH require life-long follow-up to avoid inadequate HRT, long treatment pauses and further morbidity.

Intra-articular corticoid injection induces circulating glucocorticoid bioactivity and systemic immune activation in juvenile idiopathic arthritis.

OBJECTIVE: To study the systemic effects of intra-articular (IA) glucocorticoid (GC) injections in juvenile idiopathic arthritis (JIA). METHODS: The study group comprised 21 JIA patients being treated with IA methylprednisolone [MP (n = 15) or MP plus triamcinolone hexacetonide (THA) (n = 6)] prescribed on clinical indications. The systemic effect of MP was assessed by measuring circulating glucocorticoid bioactivity (GBA) with a recombinant cell transactivation assay 7 and 24 h after the IA injections, and after 2 months. The systemic immunological responses were studied with a novel assay for testing patient serum-induced changes in the secretion of interferon (IFN)-γ and interleukin (IL)-5 from target cells. RESULTS: Administration of IA GC induced serum GBA (p = 0.001) and suppressed circulating cortisol levels (p = 0.002) 7 h after the injection. Serum withdrawn 24 h after the IA injection induced less IL-5 secretion from mitogen-activated target cells when compared with pre-treatment sera (p = 0.036). This decrease in target cell T helper (Th)2 response (IL-5) was MP dose related (r = -0.550, p = 0.018). High IL-5 secretion from target cells prior to the IA injections was associated with good clinical outcome at 2 months, seen as a low number of active (p = 0.044) and restricted joints (p = 0.049). CONCLUSION: IA GC injections have systemic effects that are reflected in the serum as an immediate elevation of GBA, a decrease of endogenous cortisol as well as a suppressive effect of patient serum on target cell IL-5 secretion. These systemic effects may play a role in the attenuation of disease activity.

Serum glucocorticoids and adiponectin associate with insulin resistance in children born small for gestational age.

OBJECTIVES: Altered glucocorticoid activity is one possible mechanism linking fetal growth restriction with later insulin resistance (IR) and type 2 diabetes. We aimed to investigate whether serum glucocorticoid parameters are related to IR in children born small for gestational age (SGA). DESIGN: A total of 110 children (55 age- and gender-matched pairs born SGA or appropriate for gestational age (AGA) in a case-control setting) were studied at the mean age of 12.2 (s.d. 0.2) years. METHODS: Serum cortisol, corticosteroid-binding globulin (CBG), free cortisol index (FCI=cortisol/CBG), and glucocorticoid bioactivity (GBA, transactivation assay) were analyzed and related to serum adiponectin and insulin-like growth factor-binding protein 1 (IGFBP1) concentrations and homeostasis model assessment for IR (HOMA-IR) and QUICKI indices. RESULTS: In the pooled study population, GBA correlated well with cortisol and FCI (r=0.681 and 0.586 respectively; P<0.001 for both). Serum cortisol, CBG, FCI, GBA, HOMA-IR, or QUICKI did not differ between the SGA and AGA subjects, but the SGA children had lower body mass index (P=0.005) and waist circumference (WC) (P=0.001). The mean GBA in the highest GBA quartile was higher among the SGA subjects than among the AGA subjects (138.6 vs 96.4 nmol/l cortisol equivalents, P<0.001). In the SGA children, GBA correlated positively with HOMA-IR (r=0.522, P<0.001) and inversely with adiponectin (r=-0.278, P=0.042) (WC/height ratio adjustments), and in logistic regression analysis, higher GBA (odds ratio (OR) 1.3; P=0.013), lower adiponectin (OR 1.4; P=0.038), and lower IGFBP1 (OR 1.9; P=0.010) associated independently with higher HOMA-IR. CONCLUSIONS: These findings suggest that increased glucocorticoid activity and low serum adiponectin concentrations associate with IR in SGA children.

Performance of a new rapid whole blood coeliac test in adult patients with low prevalence of endomysial antibodies.

BACKGROUND: In coeliac disease endomysial and transglutaminase autoantibodies are directed against the human autoantigen, transglutaminase. The conventional coeliac antibody tests are performed from serum samples in centralized laboratories. AIMS: To evaluate a rapid and easy immunoglobulin A-class whole blood point-of-care test and its commercial application, the Biocard test, in coeliac autoantibody detection. METHODS: In the whole blood point-of-care test transglutaminase is liberated from the red blood cells by haemolysis. Transglutaminase antibodies, if present, complex with the liberated antigen, and are visualized. Altogether 51 biopsy-proven untreated coeliac adult patients, 48 of the same patients after treatment, and 36 controls were tested. The point-of-care test results were compared with serum endomysial and transglutaminase antibody and Biocard test results and histology. RESULTS: The whole blood point-of-care test was as sensitive (82%) as the serum endomysium test (80%) in detecting untreated coeliac disease while the serum transglutaminase antibody test was superior (88%). The tests had 100% specificity. A positive point-of-care test result seroconverted or the test reaction weakened in 90% of the treated coeliac patients. Biocard test-positive were 22 of the 24 tested untreated coeliac patients. Biocard test-negative were 15 of 19 controls. CONCLUSIONS: The whole blood rapid tests are as reliable as the conventional serological tests in detecting untreated coeliac disease and in coeliac disease diet monitoring.

Self transglutaminase-based rapid coeliac disease antibody detection by a lateral flow method.

BACKGROUND: The conventional coeliac disease antibody tests require patient's sera, and are laborious and time-consuming. AIM: To evaluate a newly developed rapid whole blood test in coeliac disease antibody detection, and its suitability for office use. METHODS: Endogenous tissue transglutaminase found in red blood cells in a whole blood fingertip or venous sample is liberated upon haemolysis and complexes with tissue transglutaminase antibodies, if present. The complexes, captured by a lateral flow system, are visualized within 5 min. Stored samples from 121 untreated, 106 treated coeliac disease patients and 107 controls were evaluated and compared with serum endomysium and tissue transglutaminase antibody tests and histology; 150 patients were prospectively tested on site in the doctor's office. RESULTS: The rapid test showed sensitivity (96.7%) comparable with the serum endomysium and tissue transglutaminase antibody tests from stored samples; specificity was slightly lower (93.5%). When tested on site the results were concordant in 96.7% of cases compared with endomysium and tissue transglutaminase antibody results. The test recognized the disappearance of tissue transglutaminase antibodies on a gluten-free diet. CONCLUSIONS: The self tissue transglutaminase-based rapid test can be easily carried out from a fingertip blood sample on site in the physician's office for both coeliac disease case finding and dietary monitoring purposes.

Methylprednisolone exposure in pediatric renal transplant patients.

Glucocorticoid (GC) dosing is commonly based on body mass or surface area in children, although the drug effects appear to correlate with steroid exposure, rather than dose. We compared the area under the serum concentration-time curve (AUC) of methylprednisolone (MP) with a recombinant cell bioassay measuring serum glucocorticoid bioactivity (GBA), in prediction of side effects in 16 pediatric patients (5.4-18.4 years of age) 2.0-14.9 years after renal transplantation (TX). They received 0.3 mg/kg of MP orally and timed blood samples were drawn up to 8 h postdose. Serum MP concentrations correlated moderately with GBA (r= 0.65, p < 0.0001) with best linear fit at 6 and 8 h (r= 0.72, 0.79, respectively, p < 0.001). MP-AUC(t = 0-8) and GBA(t = 6) were significantly greater in patients who gained excessive weight soon after TX. Change in growth after TX was inversely correlated with MP-AUC (r= 0.73, p < 0.05) and GBA(t = 6) (r= 0.62, p < 0.05). No correlation of MP-AUC or GBA was found with blood glucose or serum lipid concentrations, glomerular filtration rate, bone mineral density or graft histology. In conclusion, GC exposure varies individually and dosing should be adjusted accordingly to control the adverse effects. GBA might provide a complementary tool for monitoring GC exposure but further studies are needed.

Coeliac disease case finding and diet monitoring by point-of-care testing.

BACKGROUND: Immunoglobulin A class transglutaminase autoantibodies are highly predictive markers of active coeliac disease, a disorder difficult to recognize solely on clinical grounds. AIMS: To develop and evaluate a simple rapid test for point-of-care detection of coeliac autoantibodies. METHODS: The novel whole blood test utilizes the patient's endogenous transglutaminase in red blood cells for detection of transglutaminase-specific immunoglobulin A antibodies present in the blood sample, with normal plasma immunoglobulin A detection as positive test control. We evaluated 284 patients under suspicion of coeliac disease and undergoing jejunal biopsy, and 263 coeliac patients on a gluten-free diet, 383 being tested prospectively in a point-of-care setting. Results were compared with histology, conventional serum autoantibody results and dietary adherence. RESULTS: The rapid test showed 97% sensitivity and 97% specificity for untreated coeliac disease, and identified all immunoglobulin A-deficient samples. Point-of-care testing found new coeliac cases as efficiently as antibody tests in laboratory. Coeliac autoantibodies were detected onsite in 21% of treated patients, while endomysial and transglutaminase antibodies were positive in 20% and 19%, respectively. The positivity rate correlated with dietary lapses and decreased on intensified dietary advice given upon positive point-of-care test results. CONCLUSIONS: Point-of-care testing was accurate in finding new coeliac cases and helped to identify and decrease dietary non-compliance.

Periplasmic stress and ECF sigma factors.

Envelope stress responses play important physiological roles in a variety of processes, including protein folding, cell wall biosynthesis, and pathogenesis. Many of these responses are controlled by extracytoplasmic function (ECF) sigma factors that respond to external signals by means of a membrane-localized anti-sigma factor. One of the best-characterized, ECF-regulated responses is the sigma(E) envelope stress response of Escherichia coli. The sigma(E) pathway ensures proper assembly of outer-membrane proteins (OMP) by controlling expression of genes involved in OMP folding and degradation in response to envelope stresses that disrupt these processes. Prevailing evidence suggests that, in E. coli, a second envelope stress response controlled by the Cpx two-component system ensures proper pilus assembly. The sensor kinase CpxA recognizes misfolded periplasmic proteins, such as those generated during pilus assembly, and transduces this signal to the response regulator CpxR through conserved phosphotransfer reactions. Phosphorylated CpxR activates transcription of periplasmic factors necessary for pilus assembly.

Novel assay for determination of androgen bioactivity in human serum.

We have developed a mammalian cell (COS-1) bioassay, which can measure androgen bioactivity directly from a small amount (10 microL) of human serum. The recombinant assay is based on androgen-dependent interaction between the ligand-binding domain and the N-terminal region of the androgen receptor (AR), which were fused to Gal4 DNA-binding domain of Saccharomyces cerevisiae and transcriptional activation domain of herpes simplex VP16 protein, respectively. The interaction is amplified by coexpression of AR-interacting protein 3 in the cells. The reporter plasmid contains 5 Gal4-binding sites upstream of the luciferase gene; luciferase activity in cell lysates is derived from androgen bioactivity in human serum. Saturating concentration of testosterone in FCS induced more than 700-fold induction in relative luciferase activity. The sensitivity was less than 1.0 nmol/L testosterone in FCS. The intra- and interassay coefficients of variation were 8.3% and 21%, respectively. Interaction between the AR termini was blocked by nonsteroidal antiandrogens, and the assay exhibited minimal cross-reactivity with 17 beta-estradiol. Serum androgen bioactivity was studied in 23 boys (13.9--16.8 yr old) with constitutional delay of puberty and in 9 prepubertal boys with cryptorchidism (1.0--6.4 yr old). Androgen bioactivity was detectable in 15 boys with constitutional delay of puberty and in all boys with cryptorchidism during treatment with human CG (range, 1.0-14.5 nmol/L testosterone equivalents). Serum androgen bioactivity measured by the bioassay correlated strongly with serum testosterone concentration (r = 0.93, P < 0.0001, n = 22) but not to 5 alpha-dihydrotestosterone, dehydroepiandrosterone, or androstenedione levels. We conclude that our novel bioassay enables quantitation of mammalian cell response to bioactive androgens in human serum, even in pediatric patients with relatively low androgen levels.

Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili.

P pili are important virulence factors in uropathogenic Escherichia coli. The Cpx two-component signal transduction system controls a stress response and is activated by misfolded proteins in the periplasm. We have discovered new functions for the Cpx pathway, indicating that it may play a critical role in pathogenesis. P pili are assembled via the chaperone/usher pathway. Subunits that go 'OFF-pathway' during pilus biogenesis generate a signal. This signal is derived from the misfolding and aggregation of subunits that failed to come into contact with the chaperone in the periplasm. In response, Cpx not only controls the stress response, but also controls genes necessary for pilus biogenesis, and is involved in regulating the phase variation of pap expression and, potentially, the expression of a panoply of other virulence factors. This study demonstrates how the prototypic chaperone/usher pathway is intricately linked and dependent upon a signal transduction system.

Tethering of CpxP to the inner membrane prevents spheroplast induction of the cpx envelope stress response.

The Cpx envelope stress response of Escherichia coli is controlled by a two-component regulatory system that senses misfolded proteins in extracytoplasmic compartments and responds by inducing the expression of envelope protein folding and degrading factors. We have proposed that in the absence of envelope stress the pathway is maintained in a downregulated state, in part through interactions between the periplasmic inhibitor molecule CpxP and the sensing domain of the histidine kinase CpxA. In this study, we show that depletion of the periplasmic contents of the cell by spheroplast formation does indeed lead to induction of the Cpx envelope stress response. Further, removal of CpxP is an important component of this induction because tethering an MBP-CpxP fusion protein to the spheroplast inner membranes prevents full activation by this treatment. Spheroplast formation has previously been demonstrated to induce the expression of a periplasmic protein of unknown function, Spy. Analysis of spy expression in response to spheroplast formation by Western blot analysis and by lacZ operon fusion in various cpx mutant backgrounds demonstrated that spy is a member of the Cpx regulon. Interestingly, although the only known spy homologue is cpxP, Spy does not appear to perform the same function as CpxP as it is not involved in inhibiting the Cpx envelope stress response. Rather, deletion of spy leads to activation of the sigmaE stress response. Because the sigmaE response is specifically affected by alterations in outer membrane protein biogenesis, we think it possible that Spy may be involved in this process.