bluuebunny/crossref_metadata_2025 huggingface dataset:
Interplay between P2Y1, P2Y12, and P2X1 receptors in the activation of megakaryocyte cation influx currents by ADP: evidence that the primary megakaryocyte represents a fully functional model of platelet P2 receptor signaling
Authors: Tolhurst Gwen , Vial Catherine , Léon Catherine , Gachet Christian , Evans Richard J. , Mahaut-Smith Martyn P.
Published: May 2005

The difficulty of conducting electrophysiologic recordings from the platelet has restricted investigations into the role of ion channels in thrombosis and hemostasis. We now demonstrate that the well-established synergy between P2Y1 and P2Y12 receptors during adenosine diphosphate (ADP)–dependent activation of the platelet αIIbβ3 integrin also exists in murine marrow megakaryocytes, further supporting the progenitor cell as a bona fide model of platelet P2 receptor signaling. In patch clamp recordings, ADP (30 μM) stimulated a transient inward current at –70 mV, which was carried by Na+ and Ca2+ and was amplified by phenylarsine oxide, a potentiator of certain transient receptor potential (TRP) ion channels by phosphatidylinositol 4,5-bisphosphate depletion. This initial current decayed to a sustained phase, upon which repetitive transient inward cation currents with pre-dominantly P2X1-like kinetics were super-imposed. Abolishing P2X1-receptor activity prevented most of the repetitive currents, consistent with their activation by secreted adenosine triphosphate (ATP). Recordings in P2Y1-receptor–deficient megakaryocytes demonstrated an essential requirement of this receptor for activation of all ADP-evoked inward currents. However, P2Y12 receptors, through the activation of PI3-kinase, played a synergistic role in both P2Y1 and P2X1-receptor–dependent currents. Thus, direct stimulation of P2Y1 and P2Y12 receptors, together with autocrine P2X1 activation, is responsible for the activation of nonselective cation currents by the platelet agonistADP.
Forced aggregation of defined numbers of human embryonic stem cells into embryoid bodies fosters robust, reproducible hematopoietic differentiation
Authors: Ng Elizabeth S. , Davis Richard P. , Azzola Lisa , Stanley Edouard G. , Elefanty Andrew G.
Published: May 2005

To realize the therapeutic potential of human embryonic stem cells (hESCs), it is necessary to regulate their differentiation in a uniform and reproducible manner. We have developed a method in which known numbers of hESCs in serum-free medium were aggregated by centrifugation to foster the formation of embryoid bodies (EBs) of uniform size (spin EBs). These spin EBs differentiated efficiently and synchronously, as evidenced by the sequential expression of molecular markers representing stem cells, primitive streak, and mesoderm. In the presence of hematopoietic growth factors, reproducible differentiation was achieved with blood cells formed in more than 90% of EBs. Using chimeric EBs generated from mixtures of green fluorescence protein–positive (GFP+) and GFP– hESCs in a clonogenic assay, hematopoietic precursor frequency was estimated to be approximately 1:500 input cells. This method of EB formation provides a generally applicable means for modulating and objectively monitoring the directed differentiation of hESCs.
Interleukin-17A mRNA and protein expression within cells from the human bronchoalveolar space after exposure to organic dust
Authors: Ivanov Stefan , Palmberg Lena , Venge Per , Larsson Kjell , Lindén Anders
Published: May 2005

Background

In mice, the cytokine interleukin (IL)-17A causes a local accumulation of neutrophils within the bronchoalveolar space. IL-17A may thereby also contribute to an increased local proteolytic burden. In the current study, we determined whether mRNA for IL-17A is elevated and protein expression of IL-17A occurs locally in inflammatory cells within the human bronchoalveolar space during severe inflammation caused by organic dust. We also assessed the expression of the elastinolytic protease MMP-9 in this airway compartment.

Methods

Six healthy, non-smoking human volunteers were exposed to organic dust in a swine confinement, a potent stimulus of neutrophil accumulation within the human bronchoalveolar space. Bronchoalveolar lavage (BAL) fluid was harvested 2 weeks before and 24 hours after the exposure and total and differential counts were conducted for inflammatory BAL cells. Messenger RNA for IL-17A was measured using reverse transcript polymerase chain reaction-enzyme linked immunoassay (RT-PCR-ELISA). Intracellular immunoreactivity (IR) for IL-17A and MMP-9, respectively, was determined in BAL cells.

Results

The exposure to organic dust caused more than a forty-fold increase of mRNA for IL-17A in BAL cells. IL-17A immunoreactivity was detected mainly in BAL lymphocytes, and the number of these IL-17A expressing lymphocytes displayed an eight-fold increase, even though not statistically significant. The increase in IL-17A mRNA was associated with a substantial increase of the number of BAL neutrophils expressing MMP-9 immunoreactivity.

Conclusion

Exposure to organic dust increases local IL-17A mRNA and because there is intracellular expression in BAL lymphocytes, this suggests that IL-17A protein can originate from lymphocytes within the human bronchoalveolar space. The fact that the increased IL-17A mRNA is associated with an increased number of MMP-9-expressing neutrophils is compatible with IL-17A increasing the local proteolytic burden through its neutrophil-accumulating effect.
GENETAG: a tagged corpus for gene/protein named entity recognition
Authors: Tanabe Lorraine , Xie Natalie , Thom Lynne H , Matten Wayne , Wilbur W John
Published: May 2005

Background

Named entity recognition (NER) is an important first step for text mining the biomedical literature. Evaluating the performance of biomedical NER systems is impossible without a standardized test corpus. The annotation of such a corpus for gene/protein name NER is a difficult process due to the complexity of gene/protein names. We describe the construction and annotation of GENETAG, a corpus of 20K MEDLINE® sentences for gene/protein NER. 15K GENETAG sentences were used for the BioCreAtIvE Task 1A Competition.

Results

To ensure heterogeneity of the corpus, MEDLINE sentences were first scored for term similarity to documents with known gene names, and 10K high- and 10K low-scoring sentences were chosen at random. The original 20K sentences were run through a gene/protein name tagger, and the results were modified manually to reflect a wide definition of gene/protein names subject to a specificity constraint, a rule that required the tagged entities to refer to specific entities. Each sentence in GENETAG was annotated with acceptable alternatives to the gene/protein names it contained, allowing for partial matching with semantic constraints. Semantic constraints are rules requiring the tagged entity to contain its true meaning in the sentence context. Application of these constraints results in a more meaningful measure of the performance of an NER system than unrestricted partial matching.

Conclusion

The annotation of GENETAG required intricate manual judgments by annotators which hindered tagging consistency. The data were pre-segmented into words, to provide indices supporting comparison of system responses to the "gold standard". However, character-based indices would have been more robust than word-based indices. GENETAG Train, Test and Round1 data and ancillary programs are freely available at ftp://ftp.ncbi.nlm.nih.gov/pub/tanabe/GENETAG.tar.gz. A newer version of GENETAG-05, will be released later this year.
Identifying gene and protein mentions in text using conditional random fields
Authors: McDonald Ryan , Pereira Fernando
Published: May 2005

Background

We present a model for tagging gene and protein mentions from text using the probabilistic sequence tagging framework of conditional random fields (CRFs). Conditional random fields model the probability P(t|o) of a tag sequence given an observation sequence directly, and have previously been employed successfully for other tagging tasks. The mechanics of CRFs and their relationship to maximum entropy are discussed in detail.

Results

We employ a diverse feature set containing standard orthographic features combined with expert features in the form of gene and biological term lexicons to achieve a precision of 86.4% and recall of 78.7%. An analysis of the contribution of the various features of the model is provided.
Systematic feature evaluation for gene name recognition
Authors: Hakenberg Jörg , Bickel Steffen , Plake Conrad , Brefeld Ulf , Zahn Hagen , Faulstich Lukas , Leser Ulf , Scheffer Tobias
Published: May 2005

In task 1A of the BioCreAtIvE evaluation, systems had to be devised that recognize words and phrases forming gene or protein names in natural language sentences. We approach this problem by building a word classification system based on a sliding window approach with a Support Vector Machine, combined with a pattern-based post-processing for the recognition of phrases. The performance of such a system crucially depends on the type of features chosen for consideration by the classification method, such as pre- or postfixes, character n-grams, patterns of capitalization, or classification of preceding or following words. We present a systematic approach to evaluate the performance of different feature sets based on recursive feature elimination, RFE. Based on a systematic reduction of the number of features used by the system, we can quantify the impact of different feature sets on the results of the word classification problem. This helps us to identify descriptive features, to learn about the structure of the problem, and to design systems that are faster and easier to understand. We observe that the SVM is robust to redundant features. RFE improves the performance by 0.7%, compared to using the complete set of attributes. Moreover, a performance that is only 2.3% below this maximum can be obtained using fewer than 5% of the features.
An inter-platform repeatability study investigating real-time amplification of plasmid DNA
Authors: Donald Carol E , Qureshi Fizza , Burns Malcolm J , Holden Marcia J , Blasic Joseph R , Woolford Alison J
Published: May 2005

Background

The wide variety of real-time amplification platforms currently available has determined that standardisation of DNA measurements is a fundamental aspect involved in the comparability of results.

Statistical analysis of the data arising from three different real-time platforms was conducted in order to assess inter-platform repeatability. On three consecutive days two PCR reaction mixes were used on each of the three amplification platforms – the LightCycler®, ABI PRISM® 7700 and Rotor Gene 3000™. Real-time PCR amplification using a fluorogenic 5' exonuclease assay was performed in triplicate on negative controls and DNA plasmid dilutions of 108–102 copies to give a total of 24 reactions per PCR experiment.

Results

The results of the statistical analyses indicated that the platform with the most precise repeatability was the ABI PRISM® 7700 when coupled with the FastStart PCR reaction mix. It was also found that there was no obvious relationship between plasmid copy number and repeatability. An ANOVA approach identified the factors that significantly affected the results, in descending order of magnitude, as: plasmid copy number, platform, PCR reaction mix and day (on which the experiment was performed).

Conclusion

In order to deliver useful, informative genetic tests, standardisation of real-time PCR detection platforms to provide repeatable, reliable results is warranted. In addition, a better understanding of inter-assay and intra-assay repeatability is required.
The subcutaneous movements of filarial infective larvae are impaired in vaccinated hosts in comparison to primary infected hosts
Authors: Babayan Simon A , Attout Tarik , Vuong Phat N , Le Goff Laetitia , Gantier Jean-Charles , Bain Odile
Published: May 2005

Our aim in this study was to observe the movements of filarial infective larvae following inoculation into the mammalian host and to assess the effect of vaccination on larval migration, in situ. Here we present recordings of larvae progressing through the subcutaneous tissues and inguinal lymph node of primary infected or vaccinated mice. We used the filaria Litomosoides sigmodontis in BALB/c mice that were necropsied 6 hours after the challenge inoculation of 200 larvae. Subcutaneous tissue sections were taken from the inoculation site and larvae were filmed in order to quantify their movements. Our analyses showed that the subcutaneous larvae were less motile in the vaccinated mice than in primary-infected mice and had more leucocytes attached to the cuticle. We propose that this reduced motility may result in the failure of a majority of larvae to evade the inflammatory reaction, thereby being a possible mechanism involved in the early vaccine-induced protection.
Economic and biological costs of cardiac imaging
Authors: Picano Eugenio
Published: May 2005

Medical imaging market consists of several billion tests per year worldwide. Out of these, at least one third are cardiovascular procedures. Keeping in mind that each test represents a cost, often a risk, and a diagnostic hypothesis, we can agree that every unnecessary and unjustifiable test is one test too many. Small individual costs, risks, and wastes multiplied by billions of examinations per year represent an important population, society and environmental burden. Unfortunately, the appropriateness of cardiac imaging is extra-ordinarily low and there is little awareness in patients and physicians of differential costs, radiological doses, and long term risks of different imaging modalities. For a resting cardiac imaging test, being the average cost (not charges) of an echocardiogram equal to 1 (as a cost comparator), the cost of a CT is 3.1x, of a SPECT 3.27x, of a Cardiovascular Magnetic Resonance imaging 5.51x, of a PET 14.03x, and of a right and left heart catheterization 19.96x. For stress cardiac imaging, compared with the treadmill exercise test equal to 1 (as a cost comparator), the cost of stress echocardiography is 2.1x and of a stress SPECT scintigraphy is 5.7x. Biohazards and downstream long-term costs linked to radiation-induced oncogenesis should also be considered. The radiation exposure is absent in echo and magnetic resonance, and corresponds to 500 chest x rays for a sestamibi cardiac stress scan and to 1150 chest x rays for a thallium scan. The corresponding extra-risk in a lifetime of fatal cancer is 1 in 2000 exposed patients for a sestamibi stress and 1 in 1000 for a thallium scan. Increased awareness of economic, biologic, and environmental costs of cardiac imaging will hopefully lead to greater appropriateness, wisdom and prudence from both the prescriber and the practitioner. In this way, the sustainability of cardiac imaging will eventually improve.
Evaluation of autoantibodies to common and neuronal cell antigens in Chronic Fatigue Syndrome
Authors: Vernon Suzanne D , Reeves William C
Published: May 2005

People with chronic fatigue syndrome (CFS) suffer from multiple symptoms including fatigue, impaired memory and concentration, unrefreshing sleep and musculoskeletal pain. The exact causes of CFS are not known, but the symptom complex resembles that of several diseases that affect the immune system and autoantibodies may provide clues to the various etiologies of CFS. We used ELISA, immunoblot and commercially available assays to test serum from subjects enrolled in a physician-based surveillance study conducted in Atlanta, Georgia and a population-based study in Wichita, Kansas for a number of common autoantibodies and antibodies to neuron specific antigens. Subsets of those with CFS had higher rates of antibodies to microtubule-associated protein 2 (MAP2) (p = 0.03) and ssDNA (p = 0.04). There was no evidence of higher rates for several common nuclear and cellular antigens in people with CFS. Autoantibodies to specific host cell antigens may be a useful approach for identifying subsets of people with CFS, identify biomarkers, and provide clues to CFS etiologies.
RNA interference: more than a research tool in the vertebrates' adaptive immunity
Authors: Mak Johnson
Published: May 2005

In recent years, RNA silencing, usage of small double stranded RNAs of ~21 – 25 base pairs to regulate gene expression, has emerged as a powerful research tool to dissect the role of unknown host cell factors in this 'post-genomic' era. While the molecular mechanism of RNA silencing has not been precisely defined, the revelation that small RNA molecules are equipped with this regulatory function has transformed our thinking on the role of RNA in many facets of biology, illustrating the complexity and the dynamic interplay of cellular regulation. As plants and invertebrates lack the protein-based adaptive immunity that are found in jawed vertebrates, the ability of RNA silencing to shut down gene expression in a sequence-specific manner offers an explanation of how these organisms counteract pathogen invasions into host cells. It has been proposed that this type of RNA-mediated defence mechanism is an ancient form of immunity to offset the transgene-, transposon- and virus-mediated attack. However, whether 1) RNA silencing is a natural immune response in vertebrates to suppress pathogen invasion; or 2) vertebrate cells have evolved to counteract invasion in a 'RNA silencing' independent manner remains to be determined. A number of recent reports have provided tantalizing clues to support the view that RNA silencing functions as a physiological response to regulate viral infection in vertebrate cells. Amongst these, two manuscripts that are published in recent issues of Science and Immunity, respectively, have provided some of the first direct evidences that RNA silencing is an important component of antiviral defence in vertebrate cells. In addition to demonstrating RNA silencing to be critical to vertebrate innate immunity, these studies also highlight the potential of utilising virus-infection systems as models to refine our understanding on the molecular determinants of RNA silencing in vertebrate cells.
Historical Perspective: S. Leonard Syme's influence on the development of social epidemiology and where we go from there
Authors: Yen Irene H
Published: May 2005

This article accompanies Len Syme's "Historical Perspective: The social determinants of disease – some roots of the movement." It describes some of Len's role in the development of social epidemiology through mentoring investigators and influencing training programs. It also discusses some challenges for the field and ways to move forward.
Why are bereaved family members dissatisfied with specialised inpatient palliative care service? A nationwide qualitative study
Authors: Shiozaki Mariko , Morita Tatsuya , Hirai Kei , Sakaguchi Yukihiro , Tsuneto Satoru , Shima Yasuo
Published: May 2005

Background: In order to improve the quality of palliative care, we can learn from bereaved families who were dissatisfied with the care they received. The primary aim of this study was to explore why bereaved families were dissatisfied with specialized inpatient palliative care. Methods: This qualitative study formed part of a nationwide questionnaire survey administered to 1225 bereaved family members of cancer patients who died in certified palliative care units in Japan. The participants were 22 consecutive family members who reported a greater need for improvement in care. Data were analysed by the content analysis. Results: The reasons that the bereaved families listed are classified into 27 categories and seven themes: (1) lack of perceived support for maintaining hope; (2) lack of perceived respect of individuality, especially in attitudes toward death; (3) perceived poor quality of care, especially psychological care, not being treated with dignity and inadequate explanation from physicians; (4) inadequate staffing and equipment, especially physician availability; (5) unavailability of timely administration; (6) lack of accurate information about palliative care units; and (7) family’s practical and economic burden. Conclusions: This study identified the multiple sources of dissatisfaction with specialized inpatient palliative care for bereaved families. These findings could be useful in developing a more desirable system of specialised inpatient palliative care.
Supportive care in the cancer setting: rhetoric or reality?
Authors: Willard C , Luker K
Published: May 2005

Background: Since 1995, UK cancer policy has been directed at organizational changes to secure improvements in treatment outcomes and quality of supportive care for cancer patients. The substantial increase in hospital-based specialist cancer nurses (SCNs) during this time suggests they have a major role to play in the delivery of supportive care. Aim: To explore how SCNs implemented their role in the context of organizational change and newly-formed multidisciplinary teams. Methods: Twenty-nine SCNs participated in observation and/or interviews, resulting in 135 hours of observation and in-depth semistructured interviews with 17 SCNs. Data were collected and analysed using a grounded theory approach. Results: The prominence of the treatment agenda the process of investigating, diagnosing and treating cancer presented the biggest challenge to the delivery of supportive care. The treatment agenda influenced how support was offered, determined professional boundaries and relegated support to a subordinate position in patient care. Conclusions: Access to supportive care is a central tenet of current cancer policy and crucial to the philosophy of patient-centred care. While SCNs are essential to the delivery of supportive care, this study highlights the challenges they encounter in organizations which prioritise treatment and improvements to treatment outcomes.
Voices of the terminally ill: uncovering the meaning of desire for euthanasia
Authors: Mak Yvonne Yi Wood , Elwyn Glyn
Published: May 2005

This study aimed to better understand the meaning of desire for euthanasia. An hermeneutic approach was undertaken using a purposively selected sample of advanced cancer patients who desired euthanasia while receiving palliative care. Unstructured interviews were conducted with six participants, which were audiotaped, transcribed and analysed. This approach allowed in-depth exploration and interpretation of the patients' lived experience. The findings illustrated a timeline from previous wellness to approaching death with five major themes: (1) reality, (2) perception, (3) anticipation, (4) desire and (5) holding environment. The desire for euthanasia is not confined to physical or psychosocial concerns relating to advanced cancer, but incorporates hidden existential yearnings for connectedness, care and respect, understood within the context of the patients' lived experience. Euthanasia requests cannot be taken at face value but require in-depth exploration of their covert meaning, in order to ensure that the patients' needs are being addressed adequately.
Lymphoedema: estimating the size of the problem
Authors: Williams Anne F , Franks Peter J , Moffatt Christine J
Published: May 2005

Lymphoedema is a problem frequently encountered by professionals working in palliative care. This article reviews the evidence on the magnitude of the problem of lymphoedema in the general population and provides evidence on specific high risk groups within it. Prevalence is a good indicator of the burden of disease for chronic problems such as lymphoedema, as it indicates the numbers of patients who require care. Incidence is indicative of changes in the causes of lymphoedema and the success of any prevention programmes. Both are important means of assessing the current level of need and the potential for the changing needs in managing this condition. Problems exist in all studies in relation to precise definitions of lymphoedema, inconsistent measures to assess differential diagnosis and poorly defined populations. While there is some evidence of high rates in relation to breast cancer therapy, the total burden of lymphoedema in the general population is largely unknown.
Should we screen hospice inpatients for orthostatic hypotension?
Authors: Chambers J C
Published: May 2005

Orthostatic hypotension (OH) is defined as a reduction in systolic blood pressure of at least 20 mm Hg or a reduction in diastolic blood pressure of at least 10 mm Hg within three minutes of standing, with a reported prevalence of 40% in the hospice setting. Dizziness, falls and fractures have been attributed to OH and some cases of symptomatic OH might be reversible. This study explored the case for screening hospice inpatients for OH. Fiftynine patients were screened up to five times and, whilst the detection rate was 27%, in no case was it reproducible. There was no statistical association between orthostatic symptoms and the detection of OH, and no patients benefited from the screening process. On closer examination of the literature, the current definition of OH might benefit from revision, sphygmomanometry is an unsatisfactory screening method and there is currently no case for screening hospice inpatients for OH.
Transitions in the lives of patients with End Stage Renal Disease: a cause of suffering and an opportunity for healing
Authors: Hutchinson Tom A
Published: May 2005

The treatment of End Stage Renal Disease (ESRD) successfully prolongs the survival of patients with kidney disease but requires that ESRD patients cope with frequent deleterious changes in their health and life situation, and shortened survival. Although the nephrology team is well-equipped to deal with the medical and technical aspects of care, it is less well-equipped to help patients with the impact of the difficult human transitions that come with dialysis and transplant treatment. Times of great challenge can also be opportunities for personal growth and healing but this often requires outside support. We need to develop new resources specifically aimed at helping ESRD patients complete important life transitions and more research on the frequency and impact of these events.
Physical Exercise in Cancer Patients During and After Medical Treatment: A Systematic Review of Randomized and Controlled Clinical Trials
Authors: Knols Ruud , Aaronson Neil K. , Uebelhart Daniel , Fransen Jaap , Aufdemkampe Geert
Published: May 2005

Purpose

To systematically review the methodologic quality of, and summarize the evidence from trials examining the effectiveness of physical exercise in improving the level of physical functioning and psychological well-being of cancer patients during and after medical treatment.

Methods

Thirty-four randomized clinical trials (RCTs) and controlled clinical trials were identified, reviewed for substantive results, and assessed for methodologic quality.

Results

Four of 34 trials met all (seven of seven) methodologic criteria on the Delphi criteria list. Failure to conceal the sequencing of treatment allocation before patient recruitment, failure to blind the outcome assessor, and failure to employ an intention-to-treat analysis strategy were the most prevalent methodologic shortcomings. Various exercise modalities have been applied, differing in content, frequency, intensity, and duration. Positive results have been observed for a diverse set of outcomes, including physiologic measures, objective performance indicators, self-reported functioning and symptoms, psychological well-being, and overall health-related quality of life.

Conclusion

The trials reviewed were of moderate methodologic quality. Together they suggest that cancer patients may benefit from physical exercise both during and after treatment. However, the specific beneficial effects of physical exercise may vary as a function of the stage of disease, the nature of the medical treatment, and the current lifestyle of the patient. Future RCTs should use larger samples, use appropriate comparison groups to rule out the possibility of an attention-placebo effect, use a comparable set of outcome measures, pay greater attention to issues of motivation and adherence of patients participating in exercise programs, and examine the effect of exercise on cancer survival.
Photorefractoriness in Mammals: Dissociating a Seasonal Timer from the Circadian-Based Photoperiod Response
Authors: Lincoln Gerald A. , Johnston Jonathan D. , Andersson Hakan , Wagner Gabriela , Hazlerigg David G.
Published: May 2005

In seasonal animals, prolonged exposure to constant photoperiod induces photorefractoriness, causing spontaneous reversion in physiology to that of the previous photoperiodic state. This study tested the hypothesis that the onset of photorefractoriness is correlated with a change in circadian expression of clock genes in the suprachiasmatic nucleus (circadian pacemaker) and the pars tuberalis (PT, a melatonin target tissue). Soay sheep were exposed to summer photoperiod (16-h light) for either 6 or 30 wk to produce a photostimulated and photorefractory physiology, and seasonal changes were tracked by measuring the long-term prolactin cycles. Animals were killed at 4-h intervals throughout 24 h. Contrary to the hypothesis, the 24-h rhythmic expression of clock genes (Rev-erbα, Per1, Per2, Bmal1, Cry1) in the suprachiasmatic nucleus and PT reflected the ambient photoperiod/melatonin signal and not the changing physiology. Contrastingly, the PT expression of α-glycoprotein hormone subunit (αGSU) and βTSH declined in photorefractory animals toward a short day-like endocrinology. We conclude that the generation of long-term endocrine cycles depends on the interaction between a circadian-based, melatonin-dependent timer that drives the initial photoperiodic response and a non-circadian-based timer that drives circannual rhythmicity in long-lived species. Under constant photoperiod the two timers can dissociate, leading to the apparent refractory state.
Dopaminergic Activation of Estrogen Receptors in Neonatal Brain Alters Progestin Receptor Expression and Juvenile Social Play Behavior
Authors: Olesen Kristin M. , Jessen Heather M. , Auger Catherine J. , Auger Anthony P.
Published: May 2005

Steroid receptor activation in developing brain influences a variety of cellular processes that endure into adulthood, altering both behavior and physiology. We report that estrogen receptors can be activated in a ligand-independent manner within developing brain by membrane dopamine receptors. Neonatal treatment with either estradiol or a dopamine D1 receptor agonist can increase the expression of an estrogen receptor-regulated gene (i.e. progestin receptors) and later juvenile social play. More importantly, increases in social play behavior induced by neonatal treatment with estradiol or a dopamine D1 receptor agonist can be prevented by prior treatment with an estrogen receptor antagonist. This suggests that changes in dopamine transmission in developing brain can activate estrogen receptors in a ligand-independent manner to influence gene expression and have lasting consequences on social behavior.
Short-Term Administration of Supraphysiological Recombinant Human Growth Hormone (GH) Does Not Increase Maximum Endurance Exercise Capacity in Healthy, Active Young Men and Women with Normal GH-Insulin-Like Growth Factor I Axes
Authors: Berggren Annika , Ehrnborg Christer , Rosén Thord , Ellegård Lars , Bengtsson Bengt-Åke , Caidahl Kenneth
Published: May 2005

Context: Despite the fact that the use of GH as a doping agent in sports is widespread, little is known about its short-term effects.

Objective: The objective was to study the effects of GH on exercise capacity.

Design: A double-blind, placebo-controlled study was used, with a treatment period of 28 d.

Setting: Subjects from general community studied ambulatory at a university hospital.

Participants: Thirty healthy active young normal volunteers (15 women and 15 men) were recruited by local announcement, and all completed the study.

Intervention: All subjects were randomized to receive a low GH dose (0.033 mg/kg·d or 0.1 IU/kg·d), a high GH dose (0.067 mg/kg·d or 0.2 IU/kg·d), or placebo.

Main outcome measures: Power output and oxygen uptake on bicycle exercise were the main outcome measures.

Results: We found no effect of the low or high dosages of GH on maximum oxygen uptake during exercise (mean ± se for placebo, 45.2 ± 1.6 to 45.2 ± 2.1 ml/kg·min; GH low dose, 42.8 ± 1.6 to 42.8 ± 1.6 ml/kg·min; GH high dose, 44.8 ± 3.4 to 44.8 ± 2.2 ml/kg·min; not significant by two-way ANOVA). Neither was there any effect on maximum achieved power output during exercise or on blood pressure, heart rate, or the electrocardiographic ST level at rest or during exercise. GH significantly increased total body weight (P = 0.028), an effect predominantly ascribed to fluid retention (increased extracellular water volume), whereas muscle mass (as indicated by intracellular water volume) did not change. However, changes in the latter correlated to changes in physical performance, possibly due to different training efforts.

Conclusion: Administration of supraphysiological recombinant human GH during a period of 4 wk does not improve power output or oxygen uptake.
Sex Hormone Suppression Reduces Resting Energy Expenditure and β-Adrenergic Support of Resting Energy Expenditure
Authors: Day Danielle S. , Gozansky Wendolyn S. , Van Pelt Rachael E. , Schwartz Robert S. , Kohrt Wendy M.
Published: May 2005

Resting energy expenditure (REE) decreases with aging and may decrease in women as a result of the menopause, potentially contributing to weight gain. REE has been observed to fluctuate during the menstrual cycle, suggesting regulation by sex hormones. The aim of the present study was to determine the effects of suppressing estrogen and progesterone on REE. Fourteen premenopausal women, 29 ± 5 yr old (mean ± sd), were studied in the midluteal menstrual phase (ML) and after 6 d of GnRH antagonist therapy (GnRHant) administered in the follicular menstrual phase. REE was measured by indirect calorimetry in the morning after a 12-h fast and again during β-adrenergic blockade to determine sympathetic nervous system (SNS) support of REE. Treatment with GnRHant significantly decreased REE (1405 ± 42 vs. 1334 ± 36 kcal/d, mean ± se, ML vs. GnRHant; P = 0.002). Additionally, SNS blockade tended to alter REE more during ML than during GnRHant (−19 ± 10 vs. 5 ± 11 kcal/d; P = 0.14). Suppression of sex hormones to postmenopausal levels by GnRHant reduced REE in young healthy women. These findings suggest that the withdrawal of estrogen and/or progesterone attenuates REE, possibly through a SNS-mediated mechanism.
The Human Glucocorticoid Receptor (GR) Isoform β Differentially Suppresses GRα-Induced Transactivation Stimulated by Synthetic Glucocorticoids
Authors: Fruchter Oren , Kino Tomoshige , Zoumakis Emmanouil , Alesci Salvatore , De Martino Massimo , Chrousos George , Hochberg Ze’ev
Published: May 2005

The β-isoform of human glucocorticoid receptor β (hGRβ) acts as a natural dominant negative inhibitor of hGRα-induced transactivation of glucocorticoid-responsive genes. We determined hGRβ ability to suppress hGRα transactivation that was induced by commonly used synthetic glucocorticoids. HepG2/C3A cells were transiently cotransfected with GR cDNA and a glucocorticoid-responsive promoter, luciferase (MMTV-luc). Transfected cells were incubated for 16 h with glucocorticoid and luciferase. For each compound, a dose-response curve was constructed, and half-maximal effective concentrations and maximal transcriptional activities were compared. hGRβ, at a 1:1 ratio to hGRα, differentially suppressed hGRα-induced maximal transcriptional activity stimulated by triamcinolone, dexamethasone, hydrocortisone, and betamethasone (by 96, 68, 62, and 49%, respectively) but not by methylprednisolone. The suppressive effect of hGRβ on hGRα-induced transactivation was stronger at lower concentrations of all tested glucocorticoids, whereas it was blunted at higher concentrations. We conclude that the potency of the dominant negative effect of hGRβ on hGRα-induced transactivation depends on both the type and the dose of the synthetic glucocorticoids in use. These results may provide helpful information concerning the selection of synthetic glucocorticoids for treatment of pathological conditions in which hGRβ modulates the sensitivity of tissues to glucocorticoids.
Growth Hormone Replacement Is Important for the Restoration of Parathyroid Hormone Sensitivity and Improvement in Bone Metabolism in Older Adult Growth Hormone-Deficient Patients
Authors: White H. D. , Ahmad A. M. , Durham B. H. , Patwala A. , Whittingham P. , Fraser W. D. , Vora J. P.
Published: May 2005

Alterations in PTH circadian rhythm and PTH target-organ sensitivity exist in adult GH-deficient (AGHD) patients and may underlie the pathogenesis of AGHD-related osteoporosis. GH replacement (GHR) results in increased bone mineral density, but its benefit in AGHD patients over 60 yr old has been debated.

To examine the effect of age on changes in PTH circadian rhythm and target-organ sensitivity after GHR, we recruited 22 AGHD patients (12 were <60 yr of age, and 10 were >60 yr of age). Half-hourly blood samples were collected for PTH, calcium, phosphate, nephrogenous cAMP (marker of renal PTH activity), type-I collagenβ C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker) before and after 1, 3, 6, and 12 months of treatment with GHR.

Significant PTH circadian rhythms were present in both age groups throughout the study. After GHR, PTH decreased and nephrogenous cAMP, adjusted calcium, and bone turnover markers increased in both groups, suggesting increased PTH target-organ sensitivity. In younger patients, the changes were significant after 1 month of GHR, but, in older patients, the changes were delayed until 3 months, with maximal changes at 12 months.

Older AGHD patients derive benefit from GHR in terms of improvement in PTH sensitivity and bone metabolism. Their response appears delayed and may explain why previous studies have not shown a positive effect of GHR on bone mineral density in older AGHD patients.
Estrogen Receptors and Estrogen-Metabolizing Enzymes in Human Ovaries during Fetal Development
Authors: Vaskivuo Tommi E. , Mäentausta Minna , Törn Svea , Oduwole Olayiwola , Lönnberg Annika , Herva Riitta , Isomaa Veli , Tapanainen Juha S.
Published: May 2005

Estrogen action plays a crucial role in many processes throughout the human life span, including development. Estrogens are pivotal in the regulation of female reproduction, but little is known about their role during ovarian development. To better understand estrogen action during ovarian development, the expression of estrogen receptors (ERs)-α and -β and key enzymes regulating estradiol production, 17β-hydroxysteroid dehydrogenases (17HSDs) types 1, 2, and 7, were analyzed in human fetal ovaries. The expression of ERs was related to the development of ovarian follicles. Before the 26th week of fetal life ERα was only occasionally detected, but from then onward, its expression was detected in ovarian follicles. Consistent expression of ERβ was seen from the 20th week until term. Both ERα and ERβ were localized to the granulosa cells and oocytes. Expression of 17HSD1 and 17HSD7 enzymes, catalyzing the conversion of estrone to more active estradiol, was detected as early as at the 17th week of fetal life. The expression of 17HSD1 displayed a pattern similar to that of ERs and increased toward term, whereas that of 17HSD7 decreased and was negative by the 36th week. 17HSD1 was localized to the granulosa cells, whereas 17HSD7 expression was more diffuse and was found in both granulosa and stromal cells. 17HSD2, converting estradiol to less potent estrone, was negative in all samples studied. The simultaneous appearance of estrogen-converting enzymes and ERs at the time of follicle formation indicates that the machinery for estrogen action exists in fetal ovaries and suggests a possible role for estrogens in the developing ovary.
Changes in Glucose Tolerance over Time in Women with Polycystic Ovary Syndrome: A Controlled Study
Authors: Legro Richard S. , Gnatuk Carol L. , Kunselman Allen R. , Dunaif Andrea
Published: May 2005

We performed this study to access the changes in glucose tolerance over time in a group of women with polycystic ovary syndrome (PCOS) (n = 71) and control women (n = 23) with regular menstrual cycles and baseline normal glucose tolerance. Mean follow-up was between 2 and 3 yr for both groups (PCOS 2.5 ± 1.7 yr; controls 2.9 ± 2.1 yr). Based on World Health Organization glucose tolerance categories, there was no significant difference in the prevalence of glucose intolerance at follow-up in the PCOS group. In the PCOS group, 25 (37%) had impaired glucose tolerance (IGT) and seven (10%) had type 2 diabetes mellitus at baseline, compared with 30 (45%) and 10 (15%), respectively, at follow-up. There were also no differences within groups (PCOS or control) or between groups (PCOS vs. control) in the oral glucose tolerance test-derived measure of insulin sensitivity, but in the women with PCOS who converted to either IGT or type 2 diabetes mellitus, there was a significant decrease (P < 0.0001). At the follow-up visit, the mean glycohemoglobin level was 6.1 ± 0.9% in women with PCOS vs. 5.3 ± 0.7% in the control women (P < 0.001). Women with PCOS and baseline IGT had a low conversion risk of 6% to type 2 diabetes over approximately 3 yr, or 2% per year. The effect of PCOS, given normal glucose tolerance (NGT) at baseline, is more pronounced with 16% conversion to IGT per year. Our study supports that women with PCOS (especially with NGT) should be periodically rescreened for diabetes due to worsening glucose intolerance over time, but this interval may be over several years and not annually.
Estrogen Receptor-α Splice Variants in the Medial Mamillary Nucleus of Alzheimer’s Disease Patients: Identification of a Novel MB1 Isoform
Authors: Ishunina Tatjana A. , Swaab Dick F. , Fischer David F.
Published: May 2005

Previously we have reported an increased nuclear estrogen receptor-α (ERα) in the medial mamillary nucleus (MMN) in Alzheimer’s disease (AD). In the present study, we addressed the presence of specific ERα mRNA splice variants in this brain area of five AD cases compared with five controls using the RT-PCR and quantitative RT-PCR approach. Indeed, the occurrence of isoforms with the deletion of exons 7 (del.7), 4 (del.4), or 2 (del.2) was determined in all patients. However, there were no significant differences in the relative transcription levels of each of the mentioned splice variants between AD and control cases, although the ratio of the del.7 isoform to the canonical ERα mRNA was higher in controls. Given that exons 7 and 4 encode the ligand-binding domain of the ERα, whereas exon 2 encodes the DNA-binding domain, abundant expression of these splice variants suggests that much of the available ERα in the MMN of AD and elderly control patients is nonfunctional because they will be unable to bind either the ligand (del.7 and del.4 variants) or the estrogen-responsive elements on appropriate DNA (del.2 variant). Yet, the wild-type ERα mRNA appeared to be 2- to 3-fold up-regulated in AD, confirming the rise in the nuclear immunocytochemical staining and pointing to the potential for a beneficial effect of estrogen replacement therapy on the MMN-associated cognitive functions in AD because it represents the availability of potentially functional ERα in the MMN. Noteworthy, the expression of the wild-type, del.7, and del.2 mRNAs declined with advanced age in both AD and control patients. Interestingly, we have identified in two AD and two control patients a novel ERα splice variant that we called MB1 (mamillary body, exon 1) with a 168-nucleotide deletion corresponding to a U2-type intron inside exon 1 encoding the major portion of the transactivation function 1 domain of the receptor.
Regulation of Proliferation, Motility, and Contractility of Human Endometrial Stromal Cells by Platelet-Derived Growth Factor
Authors: Matsumoto Harunobu , Nasu Kaei , Nishida Masakazu , Ito Hiroko , Bing Sun , Miyakawa Isao
Published: May 2005

To evaluate the involvement of platelet-derived growth factor (PDGF) isoforms (PDGF-ΑΑ, PDGF-AB, and PDGF-BB) on endometrial tissue remodeling during the perimenstrual period, we investigated the effects of PDGF on the proliferation, motility, invasiveness, and contractility of cultured human endometrial stromal cells (ESC) using a modified methylthiazoletetrazolium assay, a 5-bromo-2′-deoxyuridine incorporation assay, an in vitro wound repair assay, a chemotactic migration assay, a Transwell invasion assay, and a collagen gel contraction assay.

All three isoforms of PDGF significantly enhanced the cell proliferation, DNA synthesis, and in vitro wound repair of ESC. Chemotactic migration assay, Transwell invasion assay, and collagen gel contraction assay demonstrated that the PDGF isoforms significantly stimulated both the motility of ESC and the collagen gel contractility of ESC. PDGF-BB showed the strongest effects on these cellular functions of ESC.

The present study suggested that PDGF isoforms may promote endometrial tissue repair by enhancing the proliferation and expansion of ESC, stimulating ESC migration, and stimulating the contraction of the collagen gel matrix by ESC. By regulating ESC function during the perimenstrual period, PDGF may help to protect the endometrium from extensive fibrosis and scarring.
Whole-Body 11C-5-Hydroxytryptophan Positron Emission Tomography as a Universal Imaging Technique for Neuroendocrine Tumors: Comparison with Somatostatin Receptor Scintigraphy and Computed Tomography
Authors: Orlefors H. , Sundin A. , Garske U. , Juhlin C. , Oberg K. , Skogseid B. , Langstrom B. , Bergstrom M. , Eriksson B.
Published: May 2005

Neuroendocrine tumors (NETs) can be small and situated almost anywhere throughout the body. Our objective was to investigate whether whole-body (WB) positron emission tomography (PET) with 11C-5-hydroxytryptophan (5-HTP) can be used as a universal imaging technique for NETs and to compare this technique with established imaging methods. Forty-two consecutive patients with evidence of NET and a detected lesion on any conventional imaging (six bronchial, two foregut, 16 midgut, and two thymic carcinoids; one ectopic Cushing’s syndrome; four gastrinomas; one insulinoma; six nonfunctioning endocrine pancreatic tumors; one gastric carcinoid, one paraganglioma; and two endocrine-differentiated pancreatic carcinomas) were studied. The WB-11C-5-HTP-PET examinations were compared with WB-computed tomography (CT) and somatostatin receptor scintigraphy (SRS). Tumor lesions were imaged with PET in 95% of the patients. In 58% of the patients, PET could detect more lesions than SRS and CT and equal numbers in 34%, whereas in three cases, SRS or CT showed more lesions. In 84% (16 of 19 patients), PET could visualize the primary tumor compared with 47 and 42% for SRS and CT, respectively. The surgically removed PET-positive primary tumor sizes were 6–30 mm. To conclude, this study indicates that WB-11C-5-HTP-PET can be used as a universal imaging method for detection of NETs. This study also shows that WB-11C-HTP-PET is sensitive in imaging small NET lesions, such as primary tumors, and can in a majority of cases image significantly more tumor lesions than SRS and CT.