bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFICIENT CONTENT-BASED IMAGE RETRIEVAL USING FUZZY ORGANIZATION AND OPTIMAL RELEVANCE FEEDBACK
Authors: DOULAMIS ANASTASIOS , DOULAMIS NIKOLAOS , VARVARIGOU THEODORA
Published: January 2003

The performance of a Content-Based Image Retrieval System (CBIR) depends on (a) the system's adaptability to the user's information needs, which permits different types of indexing and simultaneously reduces the subjectivity of human perception for the interpretation of the image visual content and (b) the efficient organization of the extracted descriptors, which represent the rich visual information. Both issues are addressed in this paper. Descriptor organization is performed using a fuzzy classification scheme fragmented into multidimensional classes, instead of the previous works where fuzzy histograms were created in one dimension using, for example, the feature vector norm. Multidimensionality relates the descriptors with one another and thus allows a compact and meaningful visual representation by mapping the elements of the resulted feature vectors with a physical visual interpretation. Furthermore, fuzzy classification is applied for all visual content descriptors, in contrast to the previous approaches where only color information is exploited. Two kinds of content descriptors are extracted in our case; global-based and region-based. The first refers to the global image characteristics, while the second exploits the region-based properties. Regions are obtained by applying a multiresolution implementation of the Recursive Shortest Spanning Tree (RSST) algorithm, called M-RSST in this paper. The second issue is addressed by proposing a computationally efficient relevance feedback mechanism based on an optimal weight updating strategy. The scheme relies on the cross-correlation measure, instead of the Euclidean distance which is mainly used in most relevance feedback algorithms. Cross-correlation is a normalized measure, which expresses how similar the two feature vectors are and thus it indicates a metric of their content similarity. The proposed scheme can be recursively implemented in the case of multiple feedback iterations, instead of the previous approaches. Furthermore, it provides reliable results regardless of the number of selected sample and the feature vector size improving relevance feedback performance, as compared to other approaches.
Monoamine Transporters: From Genes to Behavior
Authors: Gainetdinov Raul R. , Caron Marc G.
Published: January 2003

Modulation of fast neurotransmission by monoamines is critically involved in numerous physiological functions and pathological conditions. Plasma membrane monoamine transporters provide one of the most efficient mechanisms controlling functional extracellular monoamine concentrations. These transporters for dopamine (DAT), serotonin (SERT), and norepinephrine (NET), which are expressed selectively on the corresponding neurons, are established targets of many psychostimulants, antidepressants, and neurotoxins. Recently, genetic animal models with targeted disruption of these transporters have become available. These mice have provided opportunities to investigate the functional importance of transporters in homeostatic control of monoaminergic transmission and to evaluate, in an in vivo model system, their roles in physiology and pathology. The use of these mice as test subjects has been helpful in resolving several important issues on specificity and mechanisms of action of certain pharmacological agents. In the present review, we summarize recent advances in understanding the physiology and pharmacology of monoamine transporters gained in mice with targeted genetic deletion of DAT, SERT, and NET.
Complementary and Alternative Therapeutics: Rigorous Research is Needed to Support Claims
Authors: Kinsel Jane F. , Straus Stephen E.
Published: January 2003

The establishment of the National Center for Complementary and Alternative Medicine (NCCAM) in 1998 as a part of the National Institutes of Health was catalyzed by the increasing interest and use of complementary and alternative medicine (CAM) modalities by the public. This article presents an overview of CAM, summarizes similarities and differences between the regulatory requirements for drugs and CAM/botanical products, identifies several challenges and opportunities for conducting research to demonstrate the safety and efficacy of CAM therapeutics, and highlights the role of NCCAM in supporting and stimulating research in this area.
Activation of the Aryl Hydrocarbon Receptor by Structurally Diverse Exogenous and Endogenous Chemicals
Authors: Denison Michael S. , Nagy Scott R.
Published: January 2003

The induction of expression of genes for xenobiotic metabolizing enzymes in response to chemical insult is an adaptive response found in most organisms. In vertebrates, the AhR is one of several chemical/ligand-dependent intracellular receptors that can stimulate gene transcription in response to xenobiotics. The ability of the AhR to bind and be activated by a range of structurally divergent chemicals suggests that the AhR contains a rather promiscuous ligand binding site. In addition to synthetic and environmental chemicals, numerous naturally occurring dietary and endogenous AhR ligands have also been identified. In this review, we describe evidence for the structural promiscuity of AhR ligand binding and discuss the current state of knowledge with regards to the activation of the AhR signaling pathway by naturally occurring exogenous and endogenous ligands.
Magnetocardiographic Rhythm Patterns at Initiation and Termination of Fetal Supraventricular Tachycardia
Authors: Wakai R.T. , Strasburger J.F. , Li Z. , Deal B.J. , Gotteiner N.L.
Published: January 2003

Background—

Using fetal magnetocardiography (fMCG), we characterize for the first time the electrophysiological patterns of initiation and termination of reentrant fetal supraventricular tachycardia (SVT), the most common form of life-threatening fetal arrhythmia.

Methods and Results—

In contrast to the expectation that reentrant SVT is initiated by spontaneous premature atrial contractions (PACs) and is terminated by spontaneous block, 5 distinct patterns of initiation and 4 patterns of termination were documented, with the most common patterns of initiation involving reentrant PACs. Waveform morphology and timing, including QRS and ventriculoatrial interval, were assessed. This enabled detection of such phenomena as Wolff-Parkinson-White syndrome, QRS aberrancy, and multiple reentrant pathways that were crucial for defining the rhythm patterns. In addition, fMCG actocardiography revealed an unexpectedly strong association between fetal trunk movement and the initiation and termination of SVT, suggesting that autonomic influences play a key role.

Conclusions—

This study demonstrates that the patterns of initiation and termination of fetal SVT are more diverse than is generally believed and that the most common patterns of initiation involve reentrant PACs. The ability to discern such patterns can help elucidate the underlying mechanisms and guide antiarrhythmic drug therapy. fMCG provides a noninvasive means of analyzing complex tachyarrhythmia in utero, with efficacy approaching that of postnatal electrocardiographic rhythm monitoring.
Interleukin-6–Deficient Mice Resist Development of Autoimmune Myocarditis Associated With Impaired Upregulation of Complement C3
Authors: Eriksson Urs , Kurrer Michael O. , Schmitz Nicole , Marsch Stephan C. , Fontana Adriano , Eugster Hans-Pietro , Kopf Manfred
Published: January 2003

Background—

Interleukin (IL)-6 regulates various aspects of the immune response. In the context of heart diseases, it has been recognized as a prognostic factor for dilated cardiomyopathy, which often results from myocarditis.

Methods and Results—

Using IL-6–deficient mice, we studied the role of IL-6 in a model of autoimmune myocarditis resulting from immunization with a peptide derived from cardiac α-myosin. Prevalence and severity of myocarditis were markedly reduced in the absence of IL-6. CD4
+
T cells from immunized IL-6–deficient mice proliferated poorly on restimulation with specific antigen in vitro and did not mediate disease on adoptive transfer into IL-6–competent RAG-2–deficient mice, which otherwise lack B cells and T cells. Production of complement C3, a crucial factor for the development of myocarditis, was strongly upregulated in IL-6
+/+
but not in IL-6–deficient mice after immunization.

Conclusions—

Our results demonstrate that IL-6 is required for the expansion of autoimmune CD4
+
T cells and the pathogenesis of autoimmune myocarditis, possibly by upregulation of complement C3.
Effect of Erythropoietin on Exercise Capacity in Patients With Moderate to Severe Chronic Heart Failure
Authors: Mancini Donna M. , Katz Stuart D. , Lang Chim C. , LaManca John , Hudaihed Alhakam , Androne Ana-Silvia
Published: January 2003

Background—

Patients with chronic heart failure (CHF) are frequently anemic. An increase in hemoglobin could enhance exercise performance by increasing oxygen delivery. We investigated the effect of erythropoietin (EPO) on exercise performance in anemic patients with CHF.

Methods and Results—

Twenty-six anemic patients aged 57±11 years were randomized to receive EPO (15 000 to 30 000 IU per week) or placebo for 3 months. Parameters measured at baseline and end therapy included blood parameters (hemoglobin, hematocrit, plasma volume), exercise parameters (peak oxygen consumption [V̇
o
2
], exercise duration, 6-minute walk), muscle aerobic metabolism (half-time of V̇
o
2
and near infrared recovery), and forearm vasodilatory function. EPO was well tolerated by all patients. Twelve patients in the EPO group felt improvement versus 1 in the placebo group (
P
<0.05). There were significant increases in hemoglobin (11.0±0.5 to 14.3±1.0 g/dL,
P
<0.05), peak V̇
o
2
(11.0±1.8 to 12.7±2.8 mL · min
−1
· kg
−1
,
P
<0.05) and exercise duration (590±107 to 657±119 s,
P
<0.004) in the EPO group but no significant changes in the control group. Resting and hyperemic forearm vascular resistance and indices of the rate of muscle oxidative capacity were unchanged in both groups.

Conclusion—

EPO significantly enhances exercise capacity in patients with CHF. One mechanism of improvement in V̇
o
2
is increased oxygen delivery from increased hemoglobin concentration.
Serum From Patients With Acute Coronary Syndromes Displays a Proapoptotic Effect on Human Endothelial Cells
Authors: Valgimigli Marco , Agnoletti Laura , Curello Salvatore , Comini Laura , Francolini Gloria , Mastrorilli Francesca , Merli Elisa , Pirani Roberto , Guardigli Gabriele , Grigolato Pier Giovanni , Ferrari Roberto
Published: January 2003

Background—

Endothelial apoptosis of atherosclerotic lesions is a possible determinant for the stable-to-vulnerable plaque transition. Recent data support the notion that plaque activation may be a pan-coronary process, advocating the existence of circulating triggers.

Methods and Results—

Serum from 40 healthy subjects (group 1) and 73 patients with stable angina (n=32; group 2) or acute coronary syndromes (n=41; group 3) was incubated with human umbilical vein endothelial cells. The percentage of apoptosis by flow cytometry and
Fas
,
Bax
, and
Bcl-2
protein expression by immunoblotting were evaluated at entry in patients and control subjects and repeated after 12 months in group 3. At baseline, apoptotic nuclei were higher in group 3 (14±6%) than in group 2 (3.3±1.8%) and group 1 (1.35±0.8%) (
P
<0.001).
Fas
and
Bcl-2
were increased in group 3 with respect to groups 1 and 2 (
P
<0.01). Coincubation of group 3 serum with anti–tumor necrosis factor-α and anti–interleukin-6 monoclonal antibodies did not affect the human umbilical vein endothelial cell apoptotic process, whereas addition of Trolox decreased apoptosis to <50%. The percentage of apoptosis in group 3 significantly correlated to the numbers of coronary complex lesions at angiography (
r
=0.58,
P
<0.0005). In group 3, apoptosis and the
Bax/Bcl-2
ratio decreased at 1 year (
P
<0.0001,
P
<0.05 respectively).

Conclusions—

Serum from patients with acute coronary syndromes displays a proapoptotic effect on human endothelial cells, supporting the theory of the existence of circulating triggers potentially able to activate atherosclerotic lesions.
Vasopressor Response to Angiotensin II Infusion in Patients With Chronic Heart Failure Receiving β-Blockers
Authors: Vittorio Timothy J. , Lang Chim C. , Katz Stuart D. , Packer Milton , Mancini Donna M. , Jorde Ulrich P.
Published: January 2003

Background—

A synergistic interaction between the angiotensin II (Ang II) type 1 receptor and α
1
-adrenergic receptors has been described. We hypothesized that the nonselective β-antagonist carvedilol, through its α
1
-adrenergic blocking properties, may modulate vascular reactivity to Ang II in patients with chronic heart failure (CHF). Accordingly, we compared the vasopressor response to infused Ang II in patients treated with carvedilol and metoprolol, a selective β-antagonist.

Methods and Results—

All subjects were treated with carvedilol or metoprolol for at least 3 months. ACE inhibitor therapy was standardized to enalapril 40 mg/d or the maximally tolerated dose. Exogenous Ang II was administered as sequential intravenous bolus injections (2.5 to 30 ng/kg) titrated to a rise in radial artery systolic pressure of ≥20 mm Hg. The dose of Ang II required to elicit a change of 20 mm Hg in radial artery systolic pressure (PD20) defined the vasopressor response to Ang II. Twenty subjects with CHF (mean left ventricular ejection fraction 28±9%, New York Heart Association class II [n=13] and III [n=7]) were studied. There was no correlation between plasma Ang II levels and PD20. However, the PD20 was significantly higher in patients treated with carvedilol than in those treated with metoprolol (20 [range 2.5 to 30] versus 5 [range 2.5 to 10] ng/kg,
P
=0.019).

Conclusions—

The vasopressor response to Ang II infusion in patients treated with carvedilol was significantly lower than in patients treated with metoprolol. Whether this is due to the α
1
-adrenergic blocking or other ancillary properties of carvedilol warrants further investigation.
Echocardiographic Predictors of Survival and Response to Early Revascularization in Cardiogenic Shock
Authors: Picard Michael H. , Davidoff Ravin , Sleeper Lynn A. , Mendes Lisa A. , Thompson Christopher R. , Dzavik Vladimir , Steingart Richard , Gin Ken , White Harvey D. , Hochman Judith S.
Published: January 2003

Background—

Although echocardiography is used in diagnosis and management of myocardial infarction, it has not been established whether specific features of cardiac structure or function early in the course of cardiogenic shock provide prognostic value. The purposes of this substudy of the SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK (SHOCK) trial were to describe the echocardiographic features of cardiogenic shock, identify findings on early echocardiograms associated with outcome, examine the interaction of such features with treatment, and determine whether these features could provide insights into the survival benefit observed with early revascularization and guide selection of patients for this strategy.

Methods and Results—

One hundred seventy-five echocardiograms performed within 24 hours of randomization to the early revascularization (ERV) or initial medical stabilization (IMS) arms of the trial were submitted for quantitative assessment, and 169 were suitable for analysis. The 2 groups were similar in terms of clinical and early echocardiographic characteristics. Mean left ventricular ejection fraction (LVEF) was 31%, and moderate or greater mitral regurgitation (MR) was noted in 39.1%. On multivariate analysis, the only independent predictors of survival were MR severity and LVEF. A survival benefit for the ERV strategy was observed at all levels of LVEF and MR.

Conclusions—

A wide range of cardiac structural and functional abnormalities exists in patients presenting with acute cardiogenic shock. Both short- and long-term mortality appear to be associated with initial left ventricular systolic function and MR as assessed by echocardiography, and a benefit of ERV is noted regardless of baseline LVEF or MR.
Statin Therapy Interacts With Cytomegalovirus Seropositivity and High C-Reactive Protein in Reducing Mortality Among Patients With Angiographically Significant Coronary Disease
Authors: Horne Benjamin D. , Muhlestein Joseph B. , Carlquist John F. , Bair Tami L. , Madsen Troy E. , Hart Noal I. , Anderson Jeffrey L.
Published: January 2003

Background—

Seropositivity to cytomegalovirus (CMV) and elevated C-reactive protein (CRP) may jointly predict increased mortality rates in patients with coronary artery disease (CAD). Therapy with statins reduces lipid levels but may also have other beneficial (eg, antiinflammatory) effects. This study prospectively evaluated the effect of statins on CMV-and CRP-associated death among patients with significant, angiographically defined CAD.

Methods and Results—

We monitored 2315 patients with angiographically significant CAD (stenosis ≥70%) for an average of 2.4 years (maximum, 5.8 years). Anti-CMV IgG antibody levels and CRP concentrations were measured at baseline, and statin prescription was recorded. As previously reported, mortality rate was higher for CMV seropositivity (+) with high CRP (hazard ratio [HR], 2.0) and lower for statins (HR, 0.50). Compared with CMV(−)/low CRP (mortality rate, 5% with statin versus 4% without statin), the protective effect of statin therapy was markedly greater for CMV(+)/low CRP (mortality rate, 2% versus 7%; HR, 0.44; 95% CI, 0.16 to 1.3), CMV negative (−)/high CRP (mortality rate, 1% versus 8%; HR, 0.16), and CMV(+)/high CRP (mortality rate, 6% versus 17%; HR, 0.42; 95% CI, 0.25 to 0.70). After adjustment, interactions were found for statin therapy with CMV(+)/low CRP (
P
for interaction=0.065), CMV(−)/high CRP (
P
for interaction=0.051), and CMV(+)/high CRP (
P
for interaction=0.024).

Conclusions—

The survival benefit of statins interacted with CMV seropositivity and high CRP to significantly reduce mortality rates among patients with CAD. This finding supports the hypothesis that statins have beneficial, “lipid-independent,” antiinflammatory effects. The mechanism of statin benefit associated with CMV seropositivity remains to be determined.
Anemia Is Common in Heart Failure and Is Associated With Poor Outcomes
Authors: Ezekowitz Justin A. , McAlister Finlay A. , Armstrong Paul W.
Published: January 2003

Background—

Although previous work has suggested that anemia is associated with an increased mortality in selected patients with congestive heart failure (CHF), little is known about the prevalence and predictors of anemia, or whether anemia is an independent prognostic factor in unselected, community-based patients with CHF.

Methods and Results—

We analyzed a population-based cohort of patients with new-onset CHF from a database of patients discharged from 138 acute-care hospitals in Alberta, Canada, between April 1993 and March 2001. Logistic regression, Kaplan-Meier survival analyses, and Cox proportional hazards model were used. Among the 12 065 patients with CHF (median age 78 years), 17% had anemia, 58% of whom had anemia of chronic disease. After adjustment for clinical and demographic variables, patients with anemia were more likely to be older (odds ratio [OR] 1.01 per year) and female (OR 1.2 [95% confidence interval 1.1 to 1.3]) and to have a history of chronic renal insufficiency (OR=3.2 [95% confidence interval 2.8 to 3.6]), or hypertension (OR 1.3 [95% confidence interval 1.2 to 1.5]). Hazard ratios for mortality, adjusting for covariates, were 1.34 (1.24 to 1.46) in anemic patients, and 1.36 (1.23 to 1.50) in those patients with anemia of chronic disease.

Conclusions—

In this large cohort of community-dwelling patients with CHF, anemia is common and an independent prognostic factor for mortality. Further research into the mechanisms of anemia in CHF and randomized controlled trials to test whether correction of anemia improves prognosis in CHF are needed.
Hemodilution Is Common in Patients With Advanced Heart Failure
Authors: Androne Ana-Silvia , Katz Stuart D. , Lund Lars , LaManca John , Hudaihed Alhakam , Hryniewicz Katarzyna , Mancini Donna M.
Published: January 2003

Background—

Anemia frequently occurs in chronic heart failure (CHF) patients and is associated with a poor prognosis. A low hematocrit may result from an increased plasma volume (hemodilution) or from reduced red blood cell volume (true anemia). The prevalence and clinical outcome of CHF patients with hemodilution is unknown.

Methods and Results—

The prevalence of anemia and its effect on outcome was examined in 196 patients with CHF. The prevalence of hemodilution was assessed in a subset of 37 ambulatory anemic patients with I
131
-tagged albumin to measure red blood cell and plasma volume. Clinical outcome was monitored. Sixty-one percent of the CHF patients were anemic. The prevalence of anemia increased from 33% in patients with New York Heart Association class II heart failure to 68% in class IV CHF patients. Survival was reduced in anemic patients compared with patients with a normal hematocrit (
P
<0.05). In the subset of 37 anemic patients, 17 patients (46%) had hemodilution and 20 patients (54%) had a true anemia. Nine patients with hemodilution died or underwent urgent transplant compared with 4 patients in the true anemia group (
P
<0.04).

Conclusion—

Hemodilution is common in CHF patients. Anemia is associated with a poor prognosis in CHF. Patients with hemodilution tend to do worse than patients with true anemia, which suggests that volume overload may be an important mechanism contributing to the poor outcome in anemic CHF patients.
Until Death Do Us Unite: Afterlife Marriages in Tang China, 618-906
Authors: Yao Ping
Published: January 2003

This article explores the minghun (afterlife marriage) practice in the Tang dynasty of China. Through a close examination of epitaphs, biographies, short stories, and archaeological discoveries, the author argues that (1) the minghun practice embodied Tang society's elaborate vision of the netherworld and new outlook toward death, enriched by the Buddhist idea of purgatory; (2) the transformed concept of afterlife and economic prosperity encouraged lavish burials and provided an opportunity for Tang parents to make up for their children's unfulfilled lives; (3) the changing perception of marriage during the Tang period, with less emphasis on the continuation of the family line and more emphasis on marital harmony and physical intimacy, led to the conviction that even deceased children deserve a marriage; and (4) minghun arrangements provided the living relatives alternate paths to form family connections, expand power, and display their wealth and social status.
Grouptask Satisfaction
Authors: Mason Claire M. , Griffin Mark A.
Published: January 2003

This article reviews evidence for considering job satisfaction at the group level of analysis. Group-level job satisfaction is functionally independent of individual-level job satisfaction. This construct is labeled group task satisfaction and is defined as the group’s shared attitude toward its task and the associated work environment. The authors propose that group task satisfaction develops out of within-group homogeneity in individual job satisfaction, which in turn is a product of the shared work conditions, social influence processes, attraction-selection-attrition effects, and emotional contagion effects associated with work groups. They predict that through group interaction, the within-group homogeneity in job satisfaction will come to be perceived as a characteristic of the group. Once identified as a group characteristic, group task satisfaction will be subject to processes such as polarization and prototyping, with the result that group task satisfaction should function independently of the mean level of job satisfaction within the group. The authors predict that group task satisfaction will be related to the mean level of individual job satisfaction within the group, the quality of the group’s processes, and the performance of the group, thus serving as an important indicator of team viability.
Transformational Leadership in Work Groups
Authors: Jung Dong I. , Sosik John J.
Published: January 2003

It has been argued that transformational leaders increase group effectiveness by empowering followers to perform their job independently from the leader, highlight the importance of cooperation in performing collective tasks, and realign followers’ values to create a more cohesive group. A study was conducted to examine whether transformational leadership would be positively related to followers’perceptions of empowerment, group cohesiveness, and effectiveness. Forty-seven groups from four Korean firms participated in this study. Results of partial least squares analysis indicated that transformational leadership was positively related to empowerment, group cohesiveness, and group effectiveness. Empowerment was positively related to collective-efficacy, which in turn was positively related to group members’ perceived group effectiveness. Implications for research and practice are discussed.
The Effects of Procedural Justice Climate on Work Group Performance
Authors: Naumann Stefanie E. , Bennett Nathan
Published: January 2003

The authors examined the effect of procedural justice climate, defined as a distinct group-level cognition about how the work group as a whole is treated, on work group performance in a sample of 34 work groups from two organizations. They hypothesized that the relationship between procedural justice climate and performance is indirect, operating through helping behavior. Group-level helping behavior fully mediated the relationship between procedural justice climate and perceived performance. However, the same results were not found when financial performance data were used as a measure of work group performance. Implications for the study’s findings are discussed.
Coexpression of Calcitonin Receptor-Like Receptor and Receptor Activity-Modifying Protein 2 or 3 Mediates the Antimigratory Effect of Adrenomedullin
Authors: Fukai Nozomi , Shichiri Masayoshi , Ozawa Naoko , Matsushita Mika , Hirata Yukio
Published: January 2003

Three isoforms of the receptor activity-modifying protein (RAMP) are thought to transport the calcitonin receptor-like receptor (CRLR) to the plasma membrane to function as calcitonin gene-related peptide or adrenomedullin receptors, but their role remains largely unknown. We investigated whether coexpression of RAMP and CRLR are involved in the regulation of cell migration using a monolayer-wounding protocol. Quantification of gene transcripts revealed expression of all RAMP isoforms and CRLR in cultured rat vascular smooth muscle cells (VSMCs), RAMP2 and RAMP3 in rat endothelial cells, and RAMP1 in rat fibroblasts. CRLR expression was minimal in endothelial cells and fibroblasts. Adrenomedullin potently suppressed the migration of VSMCs, whereas calcitonin gene-related peptide did not suppress migration in any cell type. The antimigratory effect of adrenomedullin on VSMCs was potentiated by transfecting CRLR cDNA. Cotransfection of RAMP2 or RAMP3 with CRLR into VSMCs resulted in a slower migratory rate, and this effect was enhanced by adrenomedullin. Migration of fibroblasts was also suppressed after cotransfection of RAMP2 or RAMP3 with CRLR. cAMP agonists had no effect on VSMC migration, and a cAMP antagonist failed to abrogate the antimigratory effect of adrenomedullin. Thus, coexpression of CRLR and RAMP2 or RAMP3 mediates the inhibitory effect of adrenomedullin on cell migration, independent of cAMP-dependent signaling pathways.
Two Inr Elements Are Important for Mediating the Activity of the Proximal Promoter of the Human Gonadotropin-Releasing Hormone Receptor Gene
Authors: Hoo Ruby L. C. , Ngan Elly S. W. , Leung Peter C. K. , Chow Billy K. C.
Published: January 2003

Differential usage of several transcription start sites in the human GnRH receptor gene was evident in human brain and pituitary. To locate the promoter responsible for a cluster of the 3′ CAP sites from −635 to −578 (relative to ATG) found in the pituitary, a proximal promoter element was identified at −677/−558 by 5′ and 3′ deletion mutant analysis. The promoter element drove a 13.1 ± 0.6-fold increase in reporter gene activity in an orientation-dependent manner in the mouse gonadotrope-derived αT3–1 cells. Within the core promoter element, two functional AT-rich Inr motifs, interacting with the same protein factor with different affinities, were identified. By Southwestern blot analysis and competitive gel mobility shift assays, multiple nuclear factors (36–150 kDa) were found to interact specifically with the core promoter element. Interestingly, these nuclear proteins also interacted with a previously identified distal promoter of the human GnRH receptor gene. Taken together, our studies suggested that these two promoters share common protein factors to regulate transcription initiations at two different regions. Additional mechanisms are needed to modulate the efficiencies of individual promoters for developmental and/or tissue-specific regulations.
A Transcriptionally Active Human Type II Gonadotropin-Releasing Hormone Receptor Gene Homolog Overlaps Two Genes in the Antisense Orientation on Chromosome 1q.12
Authors: Morgan Kevin , Conklin Darrell , Pawson Adam J. , Sellar Robin , Ott Thomas R. , Millar Robert P.
Published: January 2003

GnRH-II peptide hormone exhibits complete sequence conservation across vertebrate species, including man. Type-II GnRH receptor genes have been characterized recently in nonhuman primates, but the human receptor gene homolog contains a frameshift, a premature stop codon (UGA), and a 3′ overlap of the RBM8A gene on chromosome 1q.12. A retrotransposed pseudogene, RBM8B, retains partial receptor sequence. In this study, bioinformatics show that the human receptor gene promoter overlaps the peroxisomal protein11-β gene promoter and the premature UGA is positionally conserved in chimpanzee. A CGA [arginine (Arg)] occurs in porcine DNA, but UGA is shifted one codon to the 5′ direction in bovine DNA, suggesting independent evolution of premature stop codons. In contrast to marmoset tissue RNA, exon- and strand-specific probes are required to distinguish differently spliced human receptor gene transcripts in cell lines (HP75, IMR-32). RBM8B is not transcribed. Sequencing of cDNAs for spliced receptor mRNAs showed no evidence for alteration of the premature UGA by RNA editing, but alternative splicing circumvents the frameshift to encode a two-membrane-domain protein before this UGA. A stem-loop motif resembling a selenocysteine insertion sequence and a potential alternative translation initiation site might enable expression of further proteins involved in interactions within the GnRH system.
Glucose Intolerance and Resistin Expression in Rat Offspring Exposed to Ethanol in Utero: Modulation by Postnatal High-Fat Diet
Authors: Chen Li , Nyomba B. L. G.
Published: January 2003

High-fat diet and intrauterine growth retardation may predispose to obesity, insulin resistance, and type 2 diabetes. Because prenatal ethanol (ETOH) exposure causes intrauterine growth retardation, we investigated its interactions with postnatal high-fat diet on glucose tolerance and adipocyte-derived hormones in the rat offspring.

High-fat-fed offspring had increased adiposity, serum leptin, and muscle uncoupling protein-3, but decreased adiponectin mRNA, compared with corresponding chow-fed groups. ETOH-exposed offspring had normal adiponectin, but increased resistin mRNA and protein, compared with controls, regardless of postnatal diet. Skeletal muscle glucose transporter-4 content was decreased after both ETOH exposure and high-fat feeding. Glycemic and insulin responses to an ip glucose challenge were equally increased in non-ETOH-exposed high-fat-fed offspring and in ETOH-exposed chow-fed offspring, with additive effects of ETOH and high-fat diet. Pancreatic insulin content was elevated only in non-ETOH-exposed high-fat-fed offspring.

The data suggest that high-fat diet worsens glucose intolerance in offspring of rats exposed to ETOH. Prenatal ETOH exposure and postnatal high-fat diet might cause insulin resistance through separate mechanisms, involving resistin and adiponectin, respectively.
Ala/Thr201 in Extracellular Loop 2 and Leu/Phe290 in Transmembrane Domain 6 of Type 1 Frog Gonadotropin-Releasing Hormone Receptor Confer Differential Ligand Sensitivity and Signal Transduction
Authors: Seong Jae Young , Wang Li , Oh Da Young , Yun Oim , Maiti Kaushik , Li Jian Hua , Soh Jae Mok , Choi Hueng Sik , Kim Kyungjin , Vaudry Hubert , Kwon Hyuk Bang
Published: January 2003

Recently, we have identified three distinct types of bullfrog GnRH receptor (designated bfGnRHR-1, bfGnRHR-2, and bfGnRHR-3). In the present study, we have isolated three GnRHR clones in Rana dybowskii (dyGnRHR-1, dyGnRHR-2, and dyGnRHR-3). Despite high homology of dyGnRHRs with the corresponding bfGnRHRs, dyGnRHRs revealed different signaling pathways and ligand sensitivity compared with the bfGnRHR counterparts. Activation of dyGnRHRs with GnRH stimulated cAMP-mediated gene expression. However, dyGnRHR-3 but not dyGnRHR-1 and -2 induced c-fos promoter-driven gene expression. Consistently, dyGnRHR-1 and dyGnRHR-2 were not able to increase GnRH-induced inositol phosphate accumulation, whereas all bfGnRHRs and dyGnRHR-3 were, indicating that dyGnRHR-1 and dyGnRHR-2 are coupled to solely Gs, whereas all bfGnRHRs and dyGnRHR-3 are coupled to both Gs and Gq/11. Moreover, dyGnRHR-1 and dyGnRHR-2 showed about 10-fold less sensitivity to each ligand than that of the bfGnRHR counterparts. Using type 1 chimeric and point-mutated receptors, we further elucidated that specific amino acids, Ala/Thr201 in extracellular loop 2 and Leu/Phe290 in transmembrane domain 6 of the type 1 receptor, are responsible for ligand sensitivity and signal transduction pathway. Particularly, substitution of Leu290 to Phe in dyGnRHR-1 increased GnRH-induced inositol phosphate production as well as c-fos promoter-driven gene expression whereas substitution of Phe290 to Leu in bfGnRHR-1 decreased those activities. Collectively, these results demonstrate the presence of three types of GnRHR in amphibians, and suggest species- and type-specific ligand recognition and different signaling pathways in frog GnRHRs.
Sertoli and Germ Cell Development in Hypogonadal (hpg) Mice Expressing Transgenic Follicle-Stimulating Hormone Alone or in Combination with Testosterone
Authors: Haywood Miriam , Spaliviero Jenny , Jimemez Mark , King Nicholas J. C. , Handelsman David J. , Allan Charles M.
Published: January 2003

We recently created a novel transgenic (tg) model to examine the specific gonadal actions of FSH, distinct from LH effects, by expressing tg-FSH in gonadotropin-deficient hypogonadal (hpg) mice. Using this unique in vivo paradigm, we now describe the postnatal cellular development in seminiferous tubules selectively stimulated by tg-FSH alone or combined with testosterone (T). In the αβ.6 line, tg-FSH stimulated the maturation and proliferation (∼2-fold) of Sertoli cells in hpg testes. Total Sertoli cell numbers were also significantly increased (1.5-fold) independently of FSH effects by T treatment alone. Selective FSH activity in αβ.6 hpg testes increased total spermatogonia numbers 3-fold, which established a normal spermatogonia/Sertoli cell ratio. FSH also elevated meiotic spermatocyte numbers 7-fold, notably at pachytene (28-fold), but induced only limited numbers of postmeiotic haploid cells (absent in hpg controls) that arrested during spermatid elongation. In contrast, T treatment alone had little effect on postnatal spermatogonial proliferation but greatly enhanced meiotic progression with total spermatocytes increased 12-fold (pachytene 53-fold) relative to hpg testes, and total spermatid numbers 11-fold higher than tg-FSH hpg testes. Combining tg-FSH and T treatment had no further effect on Sertoli or spermatogonia numbers relative to FSH alone but had marked additive and synergistic effects on meiotic cells, particularly pachytene (107-fold more than hpg), to establish normal meiotic germ cell/Sertoli cell ratios. Furthermore, tg-FSH had a striking synergistic effect with T treatment on total spermatid numbers (19-fold higher than FSH alone), although spermatid to Sertoli cell ratios were not fully restored to normal, indicating elevated Sertoli cell numbers alone are insufficient to establish a maximal postmeiotic germ cell capacity. This unique model has allowed a detailed dissection of FSH in vivo activity alone or with T and provided compelling evidence that FSH effects on spermatogenesis are primarily via Sertoli and spermatogonial proliferation and the stimulation of meiotic and postmeiotic germ cell development in synergy with and dependent on T actions.
Thyroid Hormone Regulates Hepatic Triglyceride Mobilization and Apolipoprotein B Messenger Ribonucleic Acid Editing in a Murine Model of Congenital Hypothyroidism
Authors: Mukhopadhyay Debnath , Plateroti Michelina , Anant Shrikant , Nassir Fatiha , Samarut Jacques , Davidson Nicholas O.
Published: January 2003

Thyroid hormone modulates the expression of numerous genes that in turn regulate lipoprotein metabolism in vivo. We have examined the thyroid hormone-dependent regulation of apolipoprotein B (apoB) RNA editing in a strain of congenitally hypothyroid mice (Pax8−/−) that lacks thyroid follicular cells. Neonatal Pax8−/− mice demonstrate an approximately 10-fold increase in hepatic triglyceride content associated with a decrease in hepatic apoB RNA editing. Thyroid hormone administration resulted in hepatic triglyceride mobilization in conjunction with an increase in hepatic, but not intestinal, apoB RNA editing and without changing total apoB RNA abundance. ApoB RNA editing is mediated by a multicomponent enzyme complex whose catalytic core contains two proteins, apobec-1 and apobec-1 complementation factor (ACF). Hepatic ACF mRNA and protein abundance decreased in Pax8−/− mice, with restoration after thyroid hormone administration, whereas apobec-1 mRNA and protein abundance were unchanged. Immunohistochemical analysis revealed increased staining intensity of ACF within hepatocyte nuclei of treated mice, findings confirmed by Western analysis of isolated nuclei. In vitro RNA editing assays demonstrated that supplementation with recombinant ACF alone restored enzymatic activity of S100 extracts from hypothyroid, Pax8−/− mice. These data demonstrate that thyroid hormone modulates murine hepatic lipoprotein metabolism in association with tissue-specific effects on apoB RNA editing mediated through alterations in ACF gene expression.
Importance of the Paraventricular Nucleus of the Hypothalamus as a Component of a Neural Pathway between the Brain and the Testes that Modulates Testosterone Secretion Independently of the Pituitary
Authors: Selvage Daniel J. , Rivier Catherine
Published: January 2003

We previously reported that in adult male rats, the intracerebroventricular (icv) injection of corticotropin-releasing factor (CRF) or the β-adrenergic agonist isoproterenol (ISO) significantly inhibited the ability of human chorionic gonadotropin (hCG) to stimulate testosterone (T) secretion. The finding that this phenomenon also took place when LH release had been blocked with an LHRH antagonist suggested that icv CRF and ISO did not alter Leydig cell function by influencing the activity of pituitary gonadotrophs. We therefore proposed the existence of a neural pathway connecting the brain to the testes, whose activation by icv CRF or ISO interfered with T secretion. Based on the intratesticular injection of the transganglionic tracer pseudorabies virus, we recently identified the paraventricular nucleus (PVN) of the hypothalamus as a component of this neural link. The aim of the present work was to investigate the functional role of this brain area in mediating the ability of CRF and ISO to inhibit the ability of hCG to stimulate T secretion. We first demonstrated that local microinfusion of CRF or ISO directly into the PVN mimicked the effect of their icv injection, suggesting that the PVN does indeed represent a site of action of ISO and CRF in altering Leydig cell responsiveness to gonadotropin. In contrast, neither CRF nor ISO microinfusion into the central amygdala or the frontal cortex influenced hCG-stimulated T secretion. To further investigate the role of the PVN in ISO- and CRF-induced blunting of hCG stimulation of T, we determined the effect of icv CRF or ISO on testicular activity of rats with electrolytic lesions of the PVN. These lesions, which did not in themselves influence Leydig cell responsiveness to hCG, blocked the effect of both icv ISO and CRF on hCG-induced T release. Collectively, these results support the hypothesis that CRF- and ISO-induced activation of cells in the area of the PVN decreases the ability of gonadotropin to release T and suggests that this nucleus represents an important site of the proposed neural connection between the brain and the testes.
Molecular Target of Endocrine Disruption in Human Luteinizing Granulosa Cells by 2,3,7,8-Tetrachlorodibenzo-p-Dioxin: Inhibition of Estradiol Secretion Due to Decreased 17α-Hydroxylase/17,20-Lyase Cytochrome P450 Expression
Authors: Morán F. M. , VandeVoort C. A. , Overstreet J. W. , Lasley B. L. , Conley A. J.
Published: January 2003

Estradiol (E2) production by human luteinized granulosa cells (hLGC) is inhibited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The molecular target of TCDD toxicity has not been identified. The decrease in E2 is ameliorated by androgen substrate addition and is not associated with changes in aromatase cytochrome P450 (P450arom) activity or protein expression. An antihuman 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) antisera and a direct radiometric assay of 17,20-lyase activity were used to test the hypothesis that TCDD targets P450c17, thereby decreasing substrate availability for E2 synthesis by hLGC. P450c17 expression and 17,20-lyase activity were detected in hLGC with high levels of E2 secretion. Western immunoblot analysis demonstrated that TCDD treatment of hLGC decreased the expression of P450c17 by as much 50% (P < 0.05). TCDD exposure induced a 65% decrease in 17,20-lyase activity (P < 0.05), but no changes were seen in P450arom or in nicotinamide adenine dinucleotide phosphate (reduced)-cytochrome P450 oxidoreductase (reductase). Furthermore, the decreases in P450c17 and 17,20-lyase were proportional to the inhibition of E2 secretion. We conclude that the molecular target for endocrine disruption of hLGC by TCDD is P450c17, specifically decreasing the supply of androgens for E2 synthesis, and that it does not involve either P450arom or the redox partner protein reductase.
Minireview: Parathyroid Hormone-Related Protein as an Intracrine Factor—Trafficking Mechanisms and Functional Consequences
Authors: Fiaschi-Taesch Nathalie M. , Stewart Andrew F.
Published: January 2003

PTH-related protein (PTHrP) was originally discovered as the factor responsible for humoral hypercalcemia of malignancy. PTHrP is produced by most cell types and is a prohormone that gives rise to a family of mature secretory forms arising from posttranslational endoproteolytic cleavage of the initial translation product. Each of these secretory forms of PTHrP is believed to have one or more of its own receptors on the cell surface that mediates the normal paracrine, autocrine, and endocrine actions of PTHrP. Recently, evidence has accumulated that indicates that PTHrP is also able to enter the nucleus and/or the nucleolus and influence cellular events in an intracrine fashion. This review discusses the mechanisms by which PTHrP may gain access to the nucleus/nucleolus and the functional consequences of this nuclear entry by PTHrP.
Galanin Enhancement of Gonadotropin-Releasing Hormone-Stimulated Luteinizing Hormone Secretion in Female Rats Is Estrogen Dependent
Authors: Splett Cynthia L. , Scheffen Joseph R. , Desotelle Joshua A. , Plamann Vicky , Bauer-Dantoin Angela C.
Published: January 2003

The hypothalamic peptide GnRH is the primary neuroendocrine signal regulating pituitary LH in females. The neuropeptide galanin is cosecreted with GnRH from hypothalamic neurons, and in vitro studies have demonstrated that galanin can act at the level of the pituitary to directly stimulate LH secretion and also augment GnRH-stimulated LH secretion. Several lines of evidence have suggested that the hypophysiotropic effects of galanin are important for the generation of preovulatory LH surges. To determine whether the pituitary actions of galanin are enhanced by the preovulatory steroidal milieu, LH responses to galanin administration (with or without GnRH) were examined in: 1) ovariectomized (OVX); 2) OVX, estrogen (E)-primed; and 3) OVX, E- and progesterone-treated female rats. Results from the study indicate that galanin enhances GnRH-stimulated LH secretion only in the presence of E (in OVX, E-primed, or E- and progesterone-treated rats). Galanin alone does not directly stimulate LH secretion under any of the steroid conditions examined. In the absence of gonadal steroids (OVX rats), galanin inhibits GnRH-stimulated LH secretion. These findings suggest that the primary pituitary effect of galanin is to modulate GnRH-stimulated LH secretion, and that the potentiating effects of galanin occur only in the presence of E.
Hedgehog signalling maintains the optic stalk-retinal interface through the regulation of Vax gene activity
Authors: Take-uchi Masaya , Clarke Jonathan D. W. , Wilson Stephen W.
Published: January 2003

During early formation of the eye, the optic vesicle becomes partitioned into a proximal domain that forms the optic nerve and a distal domain that forms the retina. In this study, we investigate the activity of Nodal,Hedgehog (Hh) and Fgf signals and Vax family homeodomain proteins in this patterning event. We show that zebrafish vax1 and vax2 are expressed in overlapping domains encompassing the ventral retina, optic stalks and preoptic area. Abrogation of Vax1 and Vax2 activity leads to a failure to close the choroid fissure and progressive expansion of retinal tissue into the optic nerve, finally resulting in a fusion of retinal neurons and pigment epithelium with forebrain tissue.

We show that Hh signals acting through Smoothened act downstream of the Nodal pathway to promote Vax gene expression. However, in the absence of both Nodal and Hh signals, Vax genes are expressed revealing that other signals,which we show include Fgfs, contribute to Vax gene regulation. Finally, we show that Pax2.1 and Vax1/Vax2 are likely to act in parallel downstream of Hh activity and that the bel locus (yet to be cloned) mediates the ability of Hh-, and perhaps Fgf-, signals to induce Vax expression in the preoptic area. Taking all these results together, we present a model of the partitioning of the optic vesicle along its proximo-distal axis.
Zebrafishfoxi1mediates otic placode formation and jaw development
Authors: Solomon Keely S. , Kudoh Tetsuhiro , Dawid Igor B. , Fritz Andreas
Published: January 2003

The otic placode is a transient embryonic structure that gives rise to the inner ear. Although inductive signals for otic placode formation have been characterized, less is known about the molecules that respond to these signals within otic primordia. Here, we identify a mutation in zebrafish,hearsay, which disrupts the initiation of placode formation. We show that hearsay disrupts foxi1, a forkhead domain-containing gene, which is expressed in otic precursor cells before placodes become visible; foxi1 appears to be the earliest marker known for the otic anlage. We provide evidence that foxi1 regulates expression ofpax8, indicating a very early role for this gene in placode formation. In addition, foxi1 is expressed in the developing branchial arches, and jaw formation is disrupted in hearsay mutant embryos.