bluuebunny/crossref_metadata_2025 huggingface dataset:
Emergence of Epstein-Barr virus-associated haemophagocytic syndrome upon treatment of systemic lupus erythematosus
Authors: Kawashiri S-y , Nakamura H , Kawakami A , Ida H , Izumi Y , Tamai M , Origuchi T , Moriuchi M , Moriuchi H , Eguchi K
Published: February 2006

A 32-year-old female patient with systemic lupus erythematosus was admitted to our hospital with fever and cytopenia, and diagnosed as haemophagocytic syndrome (HPS) by bone marrow aspiration study showing haemophagocytosis. Since the serologic activity of lupus was not increased at that time and HPS was refractory to the conventional therapies, an additional aetiological factor was suspected. Real-time PCR analysis identified reactivation of Epstein-Barr virus (EBV). A combination therapy targetting EBV-associated HPS, consisting of intravenous administration of cyclosporine A as well as immunoglobulin with a high titre of anti-EBV antibody, significantly suppressed EBV viraemia and led to the remission of HPS until the time of writing.
Multi-level zero-inflated Poisson regression modelling of correlated count data with excess zeros
Authors: Lee Andy H. , Wang Kui , Scott Jane A. , Yau Kelvin K.W. , McLachlan Geoffrey J.
Published: February 2006

Count data with excess zeros relative to a Poisson distribution are common in many biomedical applications. A popular approach to the analysis of such data is to use a zero-inflated Poisson (ZIP) regression model. Often, because of the hierarchical study design or the data collection procedure, zero-inflation and lack of independence may occur simultaneously, which render the standard ZIP model inadequate. To account for the preponderance of zero counts and the inherent correlation of observations, a class of multi-level ZIP regression model with random effects is presented. Model fitting is facilitated using an expectation-maximization algorithm, whereas variance components are estimated via residual maximum likelihood estimating equations. A score test for zero-inflation is also presented. The multi-level ZIP model is then generalized to cope with a more complex correlation structure. Application to the analysis of correlated count data from a longitudinal infant feeding study illustrates the usefulness of the approach.
Evaluating markers for the early detection of cancer: overview of study designs and methods
Authors: Baker Stuart G , Kramer Barnett S , McIntosh Martin , Patterson Blossom H , Shyr Yu , Skates Steven
Published: February 2006

Background The field of cancer biomarker development has been evolving rapidly. New developments both in the biologic and statistical realms are providing increasing opportunities for evaluation of markers for both early detection and diagnosis of cancer.

Purpose To review the major conceptual and methodological issues in cancer biomarker evaluation, with an emphasis on recent developments in statistical methods together with practical recommendations.

Methods We organized this review by type of study: preliminary performance, retrospective performance, prospective performance and cancer screening evaluation.

Results For each type of study, we discuss methodologic issues, provide examples and discuss strengths and limitations.

Conclusion Preliminary performance studies are useful for quickly winnowing down the number of candidate markers; however their results may not apply to the ultimate target population, asymptomatic subjects. If stored specimens from cohort studies with clinical cancer endpoints are available, retrospective studies provide a quick and valid way to evaluate performance of the markers or changes in the markers prior to the onset of clinical symptoms. Prospective studies have a restricted role because they require large sample sizes, and, if the endpoint is cancer on biopsy, there may be bias due to overdiagnosis. Cancer screening studies require very large sample sizes and long follow-up, but are necessary for evaluating the marker as a trigger of early intervention.
Assessing diagnostic accuracy and the clinical value of positron emission tomography imaging in patients with solitary pulmonary nodules (SNAP)
Authors: Kymes Steven M , Lee Kelvin , Fletcher James W ,   SNAP (CSP 027) Study Group
Published: February 2006

Background Diagnostic tests, particularly diagnostic imaging modalities such as computed tomography (CT) and positron emission tomography (PET), have the potential to make important contributions to improved patient care and medical decision making. The expense of these tests is justified to the extent that they improve diagnostic and treatment decisions, and ultimately health outcomes. Clinical studies evaluating the accuracy of diagnostic tests and assessing their influence on decision making are essential to setting health policy and directing patient care.

Purpose We present the design and participant baseline characteristics of the Department of Veterans Affairs Cooperative Study 027 (Prospective Study of the Diagnostic Accuracy of 18F-Fluorodeoxyglucose (FDG) – Positron Emission Tomography (PET) Imaging in the Management of Patients with Solitary Pulmonary Nodules (SNAP).

Methods SNAP is a prospective, multi-site diagnostic trial to evaluate the efficacy of PET and CT for characterizing solitary pulmonary nodules. The study incorporated an assessment of the impact of these imaging modalities on clinical decision making.

Results Between January 1999 and June 2001, 10 SNAP sites enrolled 532 participants with a mean age of 66 years (SD ± 11.3), of whom 97.3% were male. A history of smoking was claimed by 93.6% of participants, with 45.7% of all participants smoking at time of enrollment. Those still smoking had an average exposure of 56.8 pack-years, while those who had quit smoking prior to enrollment had an exposure of 58.1 pack-years.

Limitations The study design reduced most common biases, but some degree of selection bias and verification bias remained. We sought to minimize verification bias by use of a dual reference standard.

Conclusion SNAP is a diagnostic test study that was designed to minimize bias and to assess a test's impact on clinical decision making, providing the kind of information most needed by clinicians and health policy makers.
Heterogeneity in disease free survival between centers: lessons learned from an EORTC breast cancer trial
Authors: Legrand Catherine , Duchateau Luc , Sylvester Richard , Janssen Paul , van der Hage Jos A , van de Velde Cornelis JH , Therasse Patrick
Published: February 2006

Background Large phase III clinical trials convey a lot of important information besides the main analysis of the treatment effect. For example, the use of multicenter clinical trial data to identify prognostic indices is now common. In addition, the study of heterogeneity in patient outcome between centers has received considerable attention in recent years. In this paper, we explain and illustrate a method used to investigate such heterogeneity with data from an early breast cancer clinical trial.

Methods The inclusion of a random effect for center in a Cox proportional hazards model allows us to study the heterogeneity in time-to-event outcomes between centers. Such a model has the major advantage that it provides a measure of the spread of outcomes over centers. This technique is illustrated using data from EORTC trial 10854, a randomized phase III trial comparing perioperative chemotherapy with no perioperative chemotherapy for early breast cancer; 2793 patients were entered by 14 centers.

Results Substantial heterogeneity between centers was detected for disease-free survival. This can be explained by the geographical area in which the center is located, with better outcomes achieved in France as compared with southern Europe and South Africa. None of the prognostic factors considered could explain this heterogeneity.

Conclusion Although clinical trials are run with the objective of removing as much heterogeneity as possible, some heterogeneity in the outcome of patients between centers may remain, as was the case in our study. The use of a random effect for center within a Cox PH model is an excellent method to investigate this heterogeneity. Such types of analyses, although exploratory, provide further insight into possible factors which may have an impact on the patient's outcome.
Sox9 in Testis Determination
Authors: KOBAYASHI AKIO , CHANG HAO , CHABOISSIER MARIE‐CHRISTINE , SCHEDL ANDREAS , BEHRINGER RICHARD R.
Published: February 2006

Abstract: Sox9 is an Sry‐box‐containing gene that encodes a transcriptional activator. During mouse gonadogenesis, Sox9 is detected in the male gonad at 11.5 days postcoitus (dpc). At 12.5 dpc, testicular cords form, morphologically distinguishing the male gonad from the ovary. From this stage onwards, Sox9 expression is restricted to the Sertoli cell lineage and persists in the adult. Humans with heterozygous mutations in SOX9 develop a skeletal syndrome known as campomelic dysplasia. Furthermore, most XY SOX9 heterozygotes show variable male‐to‐female sex reversal, implicating SOX9 in testis development. Sox9 heterozygous knockout mice die at birth with a syndrome similar to that of human campomelic dysplasia. In contrast to humans, XY Sox9+/− mice form normal appearing testes. Germ‐line knockout of Sox9 using a conditional null allele provides a tool for generating Sox9−/− mice by simple genetic crosses. However, Sox9−/− mice die soon after 11.5 dpc because of cardiovascular defects. In vitro culture of the urogenital ridges of XY Sox9−/− results in gonads lacking testicular cords and Sertoli cell marker expression, but with the expression of ovarian‐specific markers. Therefore, Sox9 is essential for diverting an intrinsically ovarian program of organogenesis toward testis formation.
Seminiferous Cord Formation and Germ‐Cell Programming: Epigenetic Transgenerational Actions of Endocrine Disruptors
Authors: SKINNER MICHAEL K. , ANWAY MATTHEW D.
Published: February 2006

Abstract: The molecular and cellular control of embryonic testis development was investigated through an analysis of the embryonic testis transcriptome to identify potential regulatory factors for male sex determination and testis morphogenesis. One critical factor identified is neurotropin 3 (NT3). At the onset of male sex determination, Sertoli cells initiate differentiation and express NT3 to act as a chemotactic factor for mesonephros cells to migrate and associate with Sertoli‐germ cell aggregates to promote cord formation. Promoter analysis suggests that NT3 may be an initial downstream gene to SRY and helps promote testis morphogenesis. Endocrine disruptors were used to potentially interfere with embryonic testis development and further investigate this biological process. The estrogenic pesticide methoxychlor and antiandrogenic fungicide vinclozolin were used. Previous studies have shown that methoxychlor and vinclozolin both interfere with embryonic testis cord formation and cause increased spermatogenic cell apoptosis in the adult testis. Interestingly, transient in vivo exposure to endocrine disruptors at the time of male sex determination caused a transgenerational phenotype (F1‐F4) of spermatogenic cell apoptosis and subfertility. This apparent epigenetic mechanism involves altered DNA methylation and permanent re‐programming of the male germ‐line. A series of genes with altered DNA methylation and imprinting are being identified. Observations reviewed demonstrate that a transient embryonic in utero exposure to an endocrine disruptor influences the embryonic testis transcriptome and through epigenetic effects (e.g., DNA methylation) results in abnormal germ‐cell differentiation that subsequently influences adult spermatogenic capacity and male fertility, and that this phenotype is transgenerational through the germ‐line. The novel observations of transgenerational epigenetic endocrine disruptor actions on male reproduction critically impact the potential hazards of these compounds as environmental toxins. The literature reviewed provides insight into the molecular and cellular control of embryonic testis development, male sex determination, and the programming of the male germ‐line.
In Vitro Generation of Germ Cells: New Techniques to Solve Current Issues
Authors: BAUGHMAN JOSHUA M. , GEIJSEN NIELS
Published: February 2006

Abstract: Primordial germ cells comprise a privileged cellular class within the embryo charged with the elite task of maintaining species longevity. While in lower organisms germ‐cell fate is determined by the allocation of germ plasm, mammalian germ‐line differentiation requires extracellular signals that converge upon the proximal epiblast. Studies using mutant mice or explanted embryos have identified some of the factors controlling primordial germ‐cell specification, such as members of the BMP family, but considerable gaps still exist in our understanding of the complete signaling network. Comprehensive investigations of mammalian germ‐line specification have been hampered by the inaccessibility of this cell population in the early embryo. Recently, however, several labs including our own have derived primordial germ cells from embryonic stem cells in vitro, thus providing a powerful new technique for the study of germ cells. In this review the different methods used for the in vitro generation of germ cells and how these techniques may be improved and applied to further advance our knowledge of germ‐cell biology are discussed.
Structure‐Function Relationships of the Luteinizing Hormone Receptor
Authors: PUETT DAVID , LI YONGSHENG , ANGELOVA KRASSIMIRA , DEMARS GENEVA , MEEHAN THOMAS P. , FANELLI FRANCESCA , NARAYAN PREMA
Published: February 2006

Abstract: Of the 800‐900 genes in the human genome that appear to encode G‐protein‐coupled receptors (GPCRs), two are known to encode receptors that bind the three heterodimeric human gonadotropins, luteinizing hormone (LH), chorionic gonadotropin (CG), and follicle‐stimulating hormone (FSH). LH and CG bind to a common receptor, LHR, and FSH binds to a paralogous receptor. These GPCRs contain a relatively large ectodomain (ECD), responsible for high‐affinity ligand binding, and a transmembrane portion, as in the other GPCRs. The ECD contains nine leucine‐rich repeats capped by N‐terminal and C‐terminal cysteine‐rich regions. The overall goal of this research is to elucidate the molecular mechanisms by which CG and LH bind to and activate LHR and the latter, in turn, activates Gsα. A combination of molecular modeling and site‐directed mutagenesis, coupled with binding and signaling studies in transiently transfected HEK 293 cells expressing wild‐type and mutant forms of LHR, has been used to develop and test models for the LHR ECD, the CG‐LHR ECD complex, and the structural changes in the transmembrane helices and intracellular loops, particularly loop 2, that accompany receptor activation. In addition, a single‐chain CG‐LHR complex was designed in which a fusion protein of the two subunits of human CG was linked to full‐length LHR. This ligand‐receptor complex was shown to be constitutively active in cellular models and in transgenic mice, the latter of which exhibit precocious puberty. From a combination of molecular modeling, site‐directed mutagenesis, genetic/protein engineering, and receptor characterization in cellular and animal models, considerable insight is being developed on the mechanisms of normal and aberrant activation of LHR.
Foxa1 and Foxa2 Interact with the Androgen Receptor to Regulate Prostate and Epididymal Genes Differentially
Authors: YU XIUPING , GUPTA APARNA , WANG YONGQING , SUZUKI KICHIYA , MIROSEVICH JANNI , ORGEBIN‐CRIST MARIE‐CLAIRE , MATUSIK ROBERT J.
Published: February 2006

Abstract: Previous studies from our group have shown that Foxa1 is expressed in the prostate and interacts with the androgen receptor (AR) to regulate prostate‐specific genes such as prostate‐specific antigen (PSA) and probasin (PB). We report here that Foxa2 but not Foxa1 is expressed in the epididymis. Further, Foxa2 interacts with the AR to regulate the mouse epididymal retinoic acid binding protein (mE‐RABP) gene, an epididymis‐specific gene. Binding of Foxa2 to the mE‐RABP promoter was confirmed by gel‐shift and chromatin immunoprecipitation (ChIP) assays. Overexpression of Foxa2 suppresses androgen activation of the mE‐RABP promoter while overexpression of Foxa2 with prostate‐specific promoters activates gene expression in an androgen‐independent manner. GST pull‐down assays determined that both Foxa1 and Foxa2 physically interact with the DNA binding domain of the AR. The interaction between Foxa proteins and AR was further confirmed by gel‐shift assays where Foxa protein was recruited to AR binding oligomers even when Foxa binding sites were not present, and AR was recruited to Foxa binding oligomers even in the absence of an AR binding site. Given that Foxa1 and Foxa2 proteins are expressed differentially in the prostate and epididymis, these data suggest that the Foxa proteins have distinct effects on AR‐regulated genes in different male reproductive accessory organs.
Role of Glial Cell Line‐Derived Neurotrophic Factor in Germ‐Line Stem Cell Fate
Authors: BRAYDICH‐STOLLE LAURA , NOLAN COURTNEY , DYM MARTIN , HOFMANN MARIE‐CLAUDE
Published: February 2006

Abstract: The overall goal of this study is to unravel the role(s) played by glial cell line‐derived neurotrophic factor (GDNF) in the fate of spermatogonial stem cells. There is great interest in the biology of spermatogonial stem cells, or Asingle spermatogonia, because of their importance in the treatment of infertility, the development of contraceptives, and the understanding of the etiology of testicular cancer, particularly seminoma. In the mouse, spermatogonial stem cells express GFRα‐1, the receptor for GDNF, and respond to this growth factor in vivo and in vitro. GDNF is produced by the adjacent Sertoli cells, which are part of the germ‐line stem cell niche in vertebrates. We specifically isolated GFRα‐1‐positive spermatogonia using an immunomagnetic bead technique. We then stimulated the cells with 100 ng/mL of rGDNF for 10 hours; unstimulated cells served as negative controls. Microarray analysis, immunocytochemistry, and Western blotting revealed that Numb, a regulator of the Notch pathway, is upregulated by GDNF in spermatogonial stem cells. There are indications that in rats, mice, and humans, the Notch pathway promotes spermatogonial differentiation. We observed that an increase in Numb expression is concomitant with Notch degradation in these cells. Thus, through Numb, GDNF might inhibit differentiation and allows the maintenance of the stem cell pool in the mouse seminiferous epithelium.
P450 Oxidoreductase Deficiency
Authors: MILLER WALTER L. , HUANG NINGWU , PANDEY AMIT V. , FLÜCK CHRISTA E. , AGRAWAL VISHAL
Published: February 2006

Abstract: Microsomal P450 enzymes, which metabolize drugs and catalyze steroid biosynthesis. require electron donation from NADPH via P450 oxidoreductase (POR). POR knockout mice are embryonically lethal, but we found recessive human POR missense mutations causing disordered steroidogenesis and Antley‐Bixler syndrome (ABS), a skeletal malformation syndrome featuring craniosynostosis. Dominant mutations in exons 8 and 10 of fibroblast growth factor receptor 2 (FGFR2) cause phenotypically related craniosynostosis syndromes and were reported in patients with ABS and normal steroidogenesis. Sequencing POR and FGFR2 exons in 32 patients with ABS and/or hormonal findings suggesting POR deficiency showed complete genetic segregation of POR and FGFR2 mutations. Fifteen patients carried POR mutations on both alleles, four carried POR mutations on 1 allele, nine carried FGFR2/3 mutations on one allele and no mutation was found in three patients. The 34 affected POR alleles included 10 with A287P, 7 with R457H, 9 other missense mutations and 7 frameshifts. These 11 missense mutations and 10 others identified by database mining were expressed in E. coli, purified to apparent homogeneity, and their catalytic capacities were measured in four assays: reduction of cytochrome c, oxidation of NADPH, and support of the 17α‐hydroxylase and 17,20 lyase activities of human P450c17. As assessed by Vmax/Km, 17,20 lyase activity provided the best correlation with clinical findings. Modeling human POR on the X‐ray crystal structure of rat POR shows that these mutant activities correlate well with their locations in the structure. POR deficiency is a new disease, distinct from the craniosynostosis syndromes caused by FGFR mutations.
Neuroendocrine Regulation of Leydig Cell Development
Authors: O'SHAUGHNESSY P. J. , BAKER P. J. , JOHNSTON H.
Published: February 2006

Abstract: During development in the mouse, two populations of Leydig cells arise sequentially. The fetal Leydig cell population arises shortly after testicular differentiation and functions primarily to produce androgens that are essential for masculinization of the fetus. The origin of the fetal Leydig stem cells remains uncertain, but it has been suggested that adrenocortical cells and fetal Leydig cells may share a common origin in an adrenogenital primordium. The fetal Leydig cells require an intact pituitary for normal development and are sensitive to both luteinizing hormone (LH) and adrenocorticotrophic hormone (ACTH). Loss of either one of these hormones does not, however, affect fetal androgen production, suggesting that both LH and ACTH may act to maintain fetal Leydig cell function in vivo in a redundant fashion. The adult Leydig cell population starts to develop soon after birth in the mouse. Initial differentiation does not appear to require gonadotropin input, but subsequent development and function are completely dependent upon LH. The adult Leydig cells do not require circulating follicle‐stimulating hormone, provided that LH is present, but androgen stimulation, through the androgen receptor, is required for normal Leydig cell development in the mouse. It is likely that the effects of androgen are mediated directly in the Leydig cells or indirectly through the peritubular cells.
Mitochondrial Function in Leydig Cell Steroidogenesis
Authors: HALES DALE B. , ALLEN JOHN A. , SHANKARA TRISTAN , JANUS PAUL , BUCK STEVE , DIEMER THORSTEN , HALES KAREN HELD
Published: February 2006

Abstract: The first and rate‐limiting step in the biosynthesis of steroid hormones is the transfer of cholesterol into mitochondria, which is facilitated by the steroidogenic acute regulatory (StAR) protein. Recent studies of Leydig cell function have focused on the molecular events controlling steroidogenesis; however, few studies have examined the importance of the mitochondria. The purpose of this investigation was to determine which aspects of mitochondrial function are necessary for Leydig cell steroidogenesis. MA‐10 tumor Leydig cells were treated with 8‐bromo‐cAMP (cAMP) and site‐specific mitochondrial disrupters, pro‐oxidants, and their effects on progesterone synthesis, StAR expression, mitochondrial membrane potential (ΔΨm) and ATP synthesis were determined. Dissipating ΔΨm with CCCP inhibited progesterone synthesis, even in the presence of newly synthesized StAR protein. The electron transport inhibitor antimycin A significantly reduced cellular ATP, inhibited steroidogenesis, and reduced StAR protein expression. The F0/F1 ATPase inhibitor oligomycin reduced cellular ATP and inhibited progesterone synthesis and StAR protein expression, but had no effect on ΔΨm) Disruption of pH with nigericin significantly reduced progesterone production and StAR protein, but had minimal effects on ΔΨm. Sodium arsenite at low concentrations inhibited StAR protein but not mRNA expression and inhibited progesterone without disrupting ΔΨm. The mitochondrial Ca2+ inhibitor Ru360 also inhibited StAR protein expression. These results demonstrate that ΔΨm, ATP synthesis, ΔpH and [Ca2+]mt are all required for steroid biosynthesis, and that mitochondria are sensitive to oxidative stress. These results suggest that mitochondria must be energized, polarized, and actively respiring to support Leydig cell steroidogenesis and alterations in the state of mitochondria may be involved in regulating steroid biosynthesis.
Postnatal and Pubertal Development of the Rhesus Monkey (Macaca mulatta) Testis
Authors: PLANT TONY M. , RAMASWAMY SURESH , SIMORANGKIR DAVID , MARSHALL GARY R.
Published: February 2006

Abstract: This review examines the neurobiology, endocrinology, and cell biology underlying the development of the testis from birth until puberty in the rhesus monkey, a representative higher primate.
Role of Nuclear Receptors in INSL3 Gene Transcription in Leydig Cells
Authors: TREMBLAY JACQUES J. , ROBERT NICHOLAS M.
Published: February 2006

Abstract: Insulin‐like 3 (INSL3) is a hormone produced by testicular Leydig cells throughout life. During embryonic life it regulates an essential step of testicular descent, whereas in adults it acts as a male germ cell survival factor. Despite the importance of INSL3 for male sex differentiation and function, very little is known regarding the molecular mechanisms that regulate its expression. So far, the nuclear receptor SF‐1 is the only transcription factor known to regulate the mouse Insl3 promoter in Leydig cells. In order to further our understanding of the transcriptional regulation of INSL3 expression, we have isolated the human INSL3 promoter and tested the effects of the nuclear receptors SF‐1, LRH‐1, and Nur77 on its activity in Leydig cells. In transfections assays, all three nuclear receptors activated the human INSL3 promoter but especially Nur77, which acted through a novel regulatory element. Thus, the human INSL3 promoter constitutes a novel target for the orphan nuclear receptor Nur77.
Analysis of the Human Sperm Proteome
Authors: JOHNSTON DANIEL S. , WOOTERS JOE , KOPF GREGORY S. , QIU YONGCHANG , ROBERTS KENNETH P.
Published: February 2006

Abstract: As part of our effort to identify putative protein targets for the development of male contraceptives, we performed an in‐depth proteomic analysis of human sperm by liquid chromatography and tandem mass spectrometry. Motile sperm were collected from a single fertile individual and fractionated into detergent‐soluble and detergent‐insoluble fractions. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis separation of these fractions, followed by manual cutting of the gel, yielded 35 gel sections for each fraction to include proteins across the full range of electrophoretic mobility. Proteomic analysis of these gel sections identified more than 1,760 proteins with high confidence, with 1,350 proteins identified in the soluble fraction, 719 identified in the insoluble fraction, and 309 identified in both fractions. This characterization of the human sperm proteome provides a high‐resolution, physiologically relevant index of the proteins that comprise human sperm.
Male Gamete Contributions to the Embryo
Authors: YANAGIMACHI RYUZO
Published: February 2006

Abstract: During normal fertilization, plasma membranes of a spermatozoon and an oocyte mingle to form a mosaic plasma membrane of a zygote. This may contribute to the polyspermy block of the zygote. Sperm tail components (mitochondria, axonema, and accessory fibers) that enter the oocyte are “digested” without playing major roles in embryo development. The proximal centrosome adjacent to the sperm nucleus may become the center of the sperm aster that brings the male and female pronuclei to the center of the zygote, but it may not be essential for embryonic development per se. Whether sperm RNAs contribute to embryonic development is the subject of controversy. The nucleus is the most important sperm component that enters the oocyte. It is known that 7‐15% of the spermatozoa of fertile men are chromosomally abnormal. The proportion of the spermatozoa with subchromosomal abnormalities (including damage at the DNA level) is expected to be even higher. The majority of embryos and fetuses with genomic abnormalities are aborted before reaching term. Structurally abnormal spermatozoa are not necessarily genomically abnormal, even though the incidence of genomically abnormal spermatozoa is higher among structurally abnormal than normal spermatozoa. In mammals, certain genes (estimated to be about 100) in the spermatozoon and oocyte must be “imprinted” in a gender‐specific manner to warrant normal embryonic development.
The Androgen Microenvironment of the Human Testis and Hormonal Control of Spermatogenesis
Authors: JAROW JONATHAN P. , ZIRKIN BARRY R.
Published: February 2006

Abstract: It is well established for both rat and man that the total testosterone concentration within the testis is far higher than that in serum. We know for the rat that intratesticular testosterone can be reduced by 50‐60% without an adverse effect on spermatogenesis but that the required intratesticular testosterone concentration is still 10‐fold greater than serum testosterone concentration. This kind of information, if available for the human, could prove invaluable for understanding and treating select men with infertility and in the development of male hormonal contraceptives. Unfortunately, we know little about the androgen content of intratesticular fluid within the human testis and nothing about the relationship between intratesticular androgens and human spermatogenesis. Using a newly developed minimally invasive technique for repetitive testicular sampling, our recent studies of the human have demonstrated that, as in the rat, there is a gradient between the concentration of testosterone in serum and within the testis; intratesticular testosterone levels were found to be 100‐fold higher than serum testosterone levels in normal men. Using liquid chromatography tandem mass spectroscopy, we have shown that intratesticular 5α‐dihydrotestosterone (DHT) levels are only 2% that of testosterone and, thus, despite greater affinity for the androgen receptor, intratesticular DHT is not significant in normal men. In order to assess how much of the testosterone within the human testis is bioactive, we adapted a highly sensitive recombinant protein mammalian cell‐based bioassay to measure androgen bioactivity. The androgen bioactivity in the normal human testis is roughly two‐thirds that of the total testosterone measurable by radioimmunoassay, despite the fact that the concentrations of the major androgen‐ binding proteins (sex hormone‐binding globulin‐ and androgen‐binding protein) are insufficient to account for this difference. This finding suggests that androgens may bind to other, as‐yet‐unknown molecules in the human testis. How, or if, this relates to spermatogenesis in the rat, or to man‐to‐man differences in the response to hormonal contraceptives, is not clear. We do not yet know how much testosterone is required within the human testis to either maintain or restore quantitatively normal spermatogenesis because, as yet, experimental studies comparable to those performed in the rat have not been feasible for the human.
Endocrine Regulation of Menstruation
Authors: Jabbour Henry N. , Kelly Rodney W. , Fraser Hamish M. , Critchley Hilary O. D.
Published: February 2006

In women, endometrial morphology and function undergo characteristic changes every menstrual cycle. These changes are crucial for perpetuation of the species and are orchestrated to prepare the endometrium for implantation of a conceptus. In the absence of pregnancy, the human endometrium is sloughed off at menstruation over a period of a few days. Tissue repair, growth, angiogenesis, differentiation, and receptivity ensue to prepare the endometrium for implantation in the next cycle. Ovarian sex steroids through interaction with different cognate nuclear receptors regulate the expression of a cascade of local factors within the endometrium that act in an autocrine/paracrine and even intracrine manner. Such interactions initiate complex events within the endometrium that are crucial for implantation and, in the absence thereof, normal menstruation. A clearer understanding of regulation of normal endometrial function will provide an insight into causes of menstrual dysfunction such as menorrhagia (heavy menstrual bleeding) and dysmenorrhea (painful periods). The molecular pathways that precipitate these pathologies remain largely undefined. Future research efforts to provide greater insight into these pathways will lead to the development of novel drugs that would target identified aberrations in expression and/or of local uterine factors that are crucial for normal endometrial function.
The Emerging Role of the Endocannabinoid System in Endocrine Regulation and Energy Balance
Authors: Pagotto Uberto , Marsicano Giovanni , Cota Daniela , Lutz Beat , Pasquali Renato
Published: February 2006

During the last few years, the endocannabinoid system has emerged as a highly relevant topic in the scientific community. Many different regulatory actions have been attributed to endocannabinoids, and their involvement in several pathophysiological conditions is under intense scrutiny. Cannabinoid receptors, named CB1 receptor and CB2 receptor, first discovered as the molecular targets of the psychotropic component of the plant Cannabis sativa, participate in the physiological modulation of many central and peripheral functions. CB2 receptor is mainly expressed in immune cells, whereas CB1 receptor is the most abundant G protein-coupled receptor expressed in the brain. CB1 receptor is expressed in the hypothalamus and the pituitary gland, and its activation is known to modulate all the endocrine hypothalamic-peripheral endocrine axes. An increasing amount of data highlights the role of the system in the stress response by influencing the hypothalamic-pituitary-adrenal axis and in the control of reproduction by modifying gonadotropin release, fertility, and sexual behavior.

The ability of the endocannabinoid system to control appetite, food intake, and energy balance has recently received great attention, particularly in the light of the different modes of action underlying these functions. The endocannabinoid system modulates rewarding properties of food by acting at specific mesolimbic areas in the brain. In the hypothalamus, CB1 receptor and endocannabinoids are integrated components of the networks controlling appetite and food intake. Interestingly, the endocannabinoid system was recently shown to control metabolic functions by acting on peripheral tissues, such as adipocytes, hepatocytes, the gastrointestinal tract, and, possibly, skeletal muscle. The relevance of the system is further strenghtened by the notion that drugs interfering with the activity of the endocannabinoid system are considered as promising candidates for the treatment of various diseases, including obesity.
Thyrotropin Stimulates the Generation of Inositol 1,4,5-Trisphosphate in Human Thyroid Cells
Authors: Van Sande Jacqueline , Dequanter Didier , Lothaire Philippe , Massart Claude , Dumont Jacques E. , Erneux Christophe
Published: February 2006

Context: Dual activation by TSH of the phospholipase C and cAMP cascades has been reported in human thyroid cells. In contrast, Singh et al. reported convincing data in FRTL-5 thyrocytes arguing against such an effect in this model. Their data in FRTL-5 cells indicated no increase in inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in response to TSH. Therefore, the authors questioned results previously obtained on human cells by cruder methodology.

Objective: We investigated the formation of inositol phosphates by HPLC techniques in human thyroid slices to separate the inositol phosphate isomers.

Results: Ins(1,4,5)P3, inositol 1,3,4-trisphosphate, and inositol 1,3,4,5-tetrakisphosphate were increased after TSH stimulation. The effect of TSH in human thyroid cells was reproduced by recombinant TSH and prevented by antibodies blocking the TSH receptor. Thyroid-stimulating antibodies at concentrations eliciting a cAMP response equivalent to TSH failed to stimulate inositol phosphate generation.

Conclusions: TSH, but not thyroid-stimulating antibodies, activates both cAMP and the phospholipase C cascade in human thyroid as now demonstrated by an increase in Ins(1,4,5)P3 and its inositol phosphate metabolites. Therefore, this effect cannot be extrapolated to the FRTL-5 cell line. The apparent discrepancy may be due to a difference between species (human vs. rat) or to the loss of the fresh tissue properties in a cell line. The dual effect of TSH in human cells, through cAMP on secretion of thyroid hormones and through the diacylglycerol, Ins(1,4,5)P3 Ca2+ pathway on thyroid hormone synthesis, implies the possible separation of these effects in thyroid disease.
Prolonged Stimulation of Growth Hormone (GH) and Insulin-Like Growth Factor I Secretion by CJC-1295, a Long-Acting Analog of GH-Releasing Hormone, in Healthy Adults
Authors: Teichman Sam L. , Neale Ann , Lawrence Betty , Gagnon Catherine , Castaigne Jean-Paul , Frohman Lawrence A.
Published: February 2006

Context: Therapeutic use of GHRH to enhance GH secretion is limited by its short duration of action.

Objective: The objective of this study was to examine the pharmacokinetic profile, pharmacodynamic effects, and safety of CJC-1295, a long-acting GHRH analog.

Design: The study design was two randomized, placebo-controlled, double-blind, ascending dose trials with durations of 28 and 49 d.

Setting: The study was performed at two investigational sites.

Participants: Healthy subjects, ages 21–61 yr, were studied.

Interventions: CJC-1295 or placebo was administered sc in one of four ascending single doses in the first study and in two or three weekly or biweekly doses in the second study.

Main Outcome Measures: The main outcome measures were peak concentrations and area under the curve of GH and IGF-I; standard pharmacokinetic parameters were used for CJC-1295.

Results: After a single injection of CJC-1295, there were dose-dependent increases in mean plasma GH concentrations by 2- to 10-fold for 6 d or more and in mean plasma IGF-I concentrations by 1.5- to 3-fold for 9–11 d. The estimated half-life of CJC-1295 was 5.8–8.1 d. After multiple CJC-1295 doses, mean IGF-I levels remained above baseline for up to 28 d. No serious adverse reactions were reported.

Conclusions: Subcutaneous administration of CJC-1295 resulted in sustained, dose-dependent increases in GH and IGF-I levels in healthy adults and was safe and relatively well tolerated, particularly at doses of 30 or 60 μg/kg. There was evidence of a cumulative effect after multiple doses. These data support the potential utility of CJC-1295 as a therapeutic agent.
Effect of Active Acromegaly and Its Treatment on Parathyroid Circadian Rhythmicity and Parathyroid Target-Organ Sensitivity
Authors: White H. D. , Ahmad A. M. , Durham B. H. , Chandran S. , Patwala A. , Fraser W. D. , Vora J. P.
Published: February 2006

Context: Patients with active acromegaly have increased bone turnover and skeletal abnormalities. Biochemical cure of acromegaly may represent a functional GH-deficient state and result in cortical bone loss. Reduced PTH target-organ sensitivity occurs in adult GH deficiency and may underlie the associated development of osteoporosis.

Objective: We examined the effect of active and treated acromegaly on PTH concentration and target-organ sensitivity.

Patients: Ten active acromegalic subjects (GH nadir > 0.3 μg/liter after 75-g oral glucose load and IGF-I above age-related reference range) and 10 matched controls participated in the study.

Design: Half-hourly blood and 3-h urine samples were collected on patients and controls for 24 h. Samples were analyzed for PTH, calcium (Ca), nephrogenous cAMP (NcAMP, a marker of PTH renal activity), β C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker). Serum calcium was adjusted for albumin (ACa). Eight acromegalic subjects who achieved biochemical cure (GH nadir < 0.3 μg/liter after 75-g oral glucose load and IGF-I within reference range) after standard surgical and/or medical treatment reattended and the protocol repeated.

Results: Active acromegalic subjects had higher 24-h mean PTH, NcAMP, ACa, urine Ca, β C-telopeptide, and procollagen type I amino-terminal propeptide (P < 0.05), compared with controls. Twenty-four-hour mean PTH increased (P < 0.001) in the acromegalic subjects after treatment, whereas NcAMP and ACa decreased (P < 0.05).

Conclusion: Increased bone turnover associated with active acromegaly may result from increased PTH concentration and action. Biochemical cure of acromegaly results in reduced PTH target-organ sensitivity indicated by increased PTH with decreased NcAMP and ACa concentrations. PTH target-organ sensitivity does not appear to return to normal after successful treatment of acromegaly in the short term and may reflect functional GH deficiency.
Fibroblast Growth Factor 23 Is Increased in Calcium Nephrolithiasis with Hypophosphatemia and Renal Phosphate Leak
Authors: Rendina Domenico , Mossetti Giuseppe , De Filippo Gianpaolo , Cioffi Michele , Strazzullo Pasquale
Published: February 2006

Context: Nephrolithiasis affects about 10% of the population in industrialized countries, with calcium salts composing more than 80% of renal stones. A significant percentage of patients with calcium nephrolithiasis and normal parathyroid function show hypophosphatemia and reduced renal phosphate reabsorption (i.e. a renal phosphate leak).

Objectives: The objective of the study was to compare serum levels of fibroblast growth factor 23 (FGF23), a regulator of phosphate homeostasis, in 110 recurrent stone formers with or without renal phosphate leak, six patients affected by X-linked hypophosphatemic rickets, five patients affected by oncogenic osteomalacia, and 60 unrelated healthy controls.

Design: This was a prospective interventional study.

Methods: Renal phosphate leak was identified based on the occurrence of idiopathic hypophosphatemia [serum phosphate concentration < 2.50 mg/dl (<0.80 mmol/liter)] and reduced renal threshold phosphate concentration [<2.2 mg/liter (<0.70 mmol/liter)].

Results: In 22 stone formers with renal phosphate leak, serum FGF23 concentration was significantly higher as compared with 88 stone formers without renal phosphate leak and with controls [83.3 (65.6–101.1) vs. 32.1 (26.8–37.4) and 24.5 (19.8–29.1) reference units (RU)/ml, respectively]. Stone formers with renal phosphate leak showed lower FGF23, compared with patients with oncogenic osteomalacia and X-linked hypophosphatemic rickets [572.3 (235.9–908.7) RU/ml]. Among stone formers and controls, serum FGF23 concentration displayed a strong inverse association with serum phosphate (r = −0.784, P = 0.009) and the rate of tubular phosphate reabsorption (r = −0.791, P = 0.008).

Conclusions: In our study population, renal phosphate leak affected 20% of stone formers and was strongly associated with increased serum FGF23 concentration.
Prolonged (48-Hour) Modest Hyperinsulinemia Decreases Nocturnal Heart Rate Variability and Attenuates the Nocturnal Decrease in Blood Pressure in Lean, Normotensive Humans
Authors: Petrova Maja , Townsend Raymond , Teff Karen L.
Published: February 2006

Context: Heart rate variability (HRV), an index of cardiac vagal activity, is decreased in individuals with metabolic disease. The relationship between decreased HRV and metabolic disease is unclear.

Objective: The objective of this study was to determine whether experimentally induced glucose intolerance decreases HRV in a circadian relevant manner in healthy individuals.

Design: This was a within-subject, randomized design study with subjects infused for 48 h with saline (50 ml/h) or 15% glucose (200 mg/m2·min). HRV was evaluated using time domain measurements taken over the 48-h period. Blood pressure and heart rate were monitored, and blood samples were taken.

Setting: This study was performed at the General Clinical Research Center of the Hospital of the University of Pennsylvania.

Patients: Sixteen healthy subjects (eight men and eight women; 18–30 yr old; mean body mass index, 21.7 ± 1.6 kg/m2) were studied.

Results: After glucose infusion, mean plasma glucose was increased by 16.8% (P < 0.0001), and plasma insulin was increased by 99.4% (P < 0.0001) compared with after saline infusion. Significant decreases in homeostasis model assessment indicated a decrease in insulin sensitivity (saline, 0.52 + 0.13; glucose, 0.34 + 0.12; P < 0.0001). The nocturnal root mean square successive difference, an index of cardiac vagal activity, was significantly decreased (P < 0.01), and nocturnal HR (P < 0.001) and blood pressure were significantly elevated (saline, 107.4 ± 2.7; glucose, 112.5 ± 3.3 mm Hg; P < 0.05) compared with the saline control. The change in homeostasis model assessment due to glucose infusion was significantly correlated with the change in root mean square successive difference (r = 0.48; P < 0.01).

Conclusions: Prolonged mild hyperinsulinemia disrupts the circadian rhythm of cardiac autonomic activity. Early changes in the neural control of cardiac activity may provide a potential mechanism mediating the pathophysiological link between impaired glucose tolerance and cardiovascular disease.
Molecular Pathology of Müller’s Muscle in Graves’ Ophthalmopathy
Authors: Shih Mei-Ju , Liao Shu-Lang , Kuo Kuan-Ting , Smith Terry J. , Chuang Lee-Ming
Published: February 2006

Context: Upper lid retraction is a common sign in Graves’ ophthalmopathy (GO). Whether Müller’s muscle is involved in upper lid retraction has not been fully elucidated.

Objective: The objective of the study was to understand the molecular pathology of Müller’s muscle in GO.

Design/Setting/Participants: A method for measurement of histological changes was developed and used to correlate severity and expression of cell-specific genes in GO.

Main Outcome Measures: Histological changes, clinical severity of upper lid retraction, and mRNA expression in Müller’s muscle in GO were measured.

Results: The degree of fibrosis correlates with severity of upper lid retraction. Macrophage infiltration was increased in fibrotic areas, consistent with higher levels of macrophage-colony stimulating factor mRNA. Levels of peroxisome proliferator-activated receptor-γ mRNA were up-regulated and correlated with fat infiltration. Decreased muscle mass correlated with lower myocardin mRNA expression. The expression of c-kit levels was decreased in diseased muscles, consistent with diminished mast cell numbers.

Conclusion: The pathological changes of Müller’s muscle correlate with clinical severity of upper lid retraction in GO. Patterns of gene expression appear to correlate with the histopathological changes in this disease process.