bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea surface temperatures and behavioural buffering capacity in thin‐billed prions Pachyptila belcheri: breeding success, provisioning and chick begging
Authors: Quillfeldt Petra , J. Strange Ian , F. Masello Juan
Published: March 2007

Seabirds are important predators in marine ecosystems and are commonly used to monitor the productivity of their marine environments. However, different measures of seabird breeding success differ in their sensitivity to environmental conditions. Here, we present an analysis of provisioning rates and chick growth as well as hatching and fledging success, in thin‐billed prions Pachyptila belcheri at New Island, Falkland Islands between 2003 and 2005 and relate these patterns to ocean climate. During the study period, SST were rising within and between breeding seasons and were negatively correlated with provisioning frequencies of thin‐billed prions. Chick mass was reduced and begging intensities increased at low feeding frequencies, but overall breeding success and fledging success were not affected, because most chicks in survived to fledging despite poor provisioning rates. Chick numbers and survival therefore may not be sensitive indicators of environmental conditions in all seabird species and ranges of food abundance. Monitoring behavioural buffering mechanisms, such as feeding rates, may be more effective in some ranges of food abundance and time scales and provide an earlier warning of ecological change. As a novel technique, the use of begging intensities as indicator of chick body condition is proposed in species where repeated handling causes disturbance. The present data suggest that begging rates can serve as a non‐invasive method to monitor chick condition.
Relative abundance of males to females affects behaviour, condition and immune function in a captive population of dark‐eyed juncos Junco hyemalis
Authors: J. Greives Timothy , M. Casto Joseph , D. Ketterson Ellen
Published: March 2007

Relative numbers of males and females in breeding groups may vary from expected values owing to a variety of factors. To determine how sex ratio might influence individual phenotypes in a captive population of dark‐eyed juncos Junco hyemalis during the breeding season, we established three treatment groups: a male‐biased (2:1), equal (1:1), and female‐biased group (1:2). Within‐group density (birds/m2) was constant across groups. We assessed the frequency of flight chases (a proxy for social instability), measured changes in body mass and pectoral muscle condition, assayed plasma levels of testosterone (T) and compared cell‐mediated immunity of individuals. We found significantly more chases in the male‐biased group than in the female‐biased group. Birds in the male‐biased group lost more mass and displayed poorer pectoral‐muscle condition than birds in the equal group. Cell‐mediated immune responses were reduced in individuals in the male‐biased group in comparison to the female‐biased group. Plasma T levels in both sexes did not vary with sex ratio. Collectively, these results suggest that during the breeding season, social instability is greater in male‐biased populations, and instability may lead to decreased general health and vigour.
Plasticity of inwardly rectifying conductances following a corticospinal lesion in human subjects
Authors: Jankelowitz Stacey K. , Howells James , Burke David
Published: March 2007

This study investigated whether there are changes in the excitability of motor axons in peripheral nerves of patients with corticospinal lesions, reflecting plasticity of the motoneuron due to altered descending drives and/or changes in afferent feedback. The excitability of motor and sensory axons in peripheral nerves of the affected limb of 11 patients with unilateral hemiparesis due to stroke was compared with that for the unaffected limbs and with data for 12 age‐matched controls. There was significantly less accommodation to hyperpolarizing currents in motor axons on the affected side. There were small differences between the data for the unaffected side and that of the control subjects but these were not statistically significant. Other findings indicate that there was no change in resting membrane potential. There was no comparable alteration in the excitability of sensory axons. The changes in response of motor axons to hyperpolarizing currents could be reproduced in a computer model of the human motor axon by reducing the hyperpolarization‐activated conductance, IH, by 30% and the quantitatively small leak conductance by 77%. The data for the uninvolved side matched the data for control subjects best when IH was increased. These findings are consistent with modulation of IH by activity. They demonstrate a change in the biophysical properties of motor axons not directly affected by the pathology and synaptically remote from the lesion, and have implications for ‘trans‐synaptic’ changes in central nervous system pathways. In human subjects studies of motor axon properties may allow insight into processes affecting the motoneuron.
Spontaneous hypersensitivity in mesenteric afferent nerves of mice deficient in the sst2 subtype of somatostatin receptor
Authors: Rong Weifang , Winchester Wendy J. , Grundy David
Published: March 2007

Somatostatin is an inhibitory peptide present in abundance in the gastrointestinal (GI) tract. The effects of somatostatin are mediated through its interaction with a family of G‐protein‐coupled receptors, namely sst1–5. Previous evidence suggested that the sst2 receptor mediates an inhibitory role of somatostatin on GI afferent nerve sensitivity. In the present study we further evaluated mechanical and chemical sensitivity of mesenteric afferents in mice deficient in the sst2 receptor. Multi‐unit recordings were made from mesenteric afferents from mouse jejunal segments perfused in vitro. Ramp distension of the jejunum up to 60 mmHg induced biphasic increases in afferent activity in both wild‐type (WT) and sst2 gene knock‐out (KO) mice. However, the level of afferent activity was significantly higher in the KO (n= 15) compared to the WT (n= 16) mice across the entire pressure range. The mesenteric afferent sensitivity to acid was evaluated by intraluminal infusion of hydrochloric acid (HCl 20 mm) for 2 min. Peak afferent discharge rate following acid infusion was significantly greater in KO (36.76 ± 6.47 impulses s−1, n= 7) than in WT preparations (16.53 ± 3.91 impulses s−1, n= 5, P < 0.01). The response to bath‐applied bradykinin (1 μm, 3 ml) was not significantly different in the KO and the WT preparations. It is interesting that in the WT preparations, octreotide inhibited both low‐ and high‐threshold mechanosensory responses, whereas in the sst2 KO group it appeared to inhibit the low‐threshold responses preferentially and failed to affect the high‐threshold responses. The results of the present investigation demonstrate that sst2 deficiency is associated with exaggerated jejunal afferent sensitivity to both mechanical and chemical stimulations, suggesting that somatostatin plays an important inhibitory role in the control of visceral sensitivity by interacting with the sst2 receptor.
Potassium initiates vasodilatation induced by a single skeletal muscle contraction in hamster cremaster muscle
Authors: Armstrong Marika L. , Dua Ashok K. , Murrant Coral L.
Published: March 2007

The rapid onset of vasodilatation within seconds of a single contraction suggests that the vasodilators involved may be products of skeletal muscle activation, such as potassium (K+). To test the hypothesis that K+ was in part responsible for the rapid dilatation produced by muscle contraction we stimulated four to five skeletal muscle fibres in the anaesthetized hamster cremaster preparation in situ and measured the change in diameter of arterioles at a site of overlap with the stimulated muscle fibres before and after a single contraction stimulated over a range of stimulus frequencies (4, 10, 20, 30, 40, 60 and 80 Hz; 250 ms train duration). Muscle fibres were stimulated in the absence and presence of an inhibitor of a source of K+, the voltage dependent K+ channel inhibitor 3,4‐diaminopyridine (DAP, 3 × 10−4m) and inhibitors of the K+ dilatory signal transduction pathway, either a Na+ K+‐ATPase inhibitor (ouabain; 10−4m) or an inward rectifying K+ channel inhibitor (barium chloride, BaCl2; 5 × 10−5m). We observed significant inhibitions of the rapid dilatation at all stimulus frequencies with each inhibitor. The dilatory event at 4 s was significantly inhibited at all stimulus frequencies by an average of 65.7 ± 3.6%, 58.8 ± 6.1% and 64.4 ± 2.1% in the presence DAP, ouabain and BaCl2, respectively. These levels of inhibition did not correlate with non‐specific changes in force generation by skeletal muscle measured in vitro. Therefore, our data support that K+ is involved in the rapid dilatation in response to a single muscle contraction across a wide range of stimulus frequencies.
Early Optical Polarization of a Gamma-Ray Burst Afterglow
Authors: Mundell Carole G. , Steele Iain A. , Smith Robert J. , Kobayashi Shiho , Melandri Andrea , Guidorzi Cristiano , Gomboc Andreja , Mottram Chris J. , Clarke David , Monfardini Alessandro , Carter David , Bersier David
Published: March 2007

We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of γ-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2σ) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.
The Hitchhiker's Guide to Tobacco Control: A Global Assessment of Harms, Remedies, and Controversies
Authors: Davis Ronald M. , Wakefield Melanie , Amos Amanda , Gupta Prakash C.
Published: March 2007

One in three adults worldwide (>1.1 billion people) smokes; 80% live in low- and middle-income countries. Tobacco use causes five million deaths each year and, if current smoking patterns continue, will kill 10 million persons annually by 2020. From 1970 to 2000, tobacco leaf production decreased by 36% in developed countries but more than doubled in developing countries. China is the world's leading producer and consumer of tobacco. Seven multinational tobacco companies dominate the world cigarette market, led by Altria, British American Tobacco, and Japan Tobacco, which collectively manufacture more than 2 trillion cigarettes per year. Extensive knowledge exists about effective tobacco control interventions. However, dissemination of best practices and adoption and implementation of recommended policies are fragmentary. The Framework Convention on Tobacco Control (ratified by 140 countries as of October 1, 2006) provides a template outlining the ingredients for a comprehensive tobacco control campaign.
Lessons from Cost-Effectiveness Research for United States Public Health Policy
Authors: Grosse Scott D. , Teutsch Steven M. , Haddix Anne C.
Published: March 2007

The application of cost-effectiveness analysis to health care has been the subject of previous reviews. We address the use of economic evaluation methods in public health, including case studies of population-level policies, e.g., environmental regulations, injury prevention, tobacco control, folic acid fortification, and blood product safety, and the public health promotion of clinical preventive services, e.g., newborn screening, cancer screening, and childhood immunizations. We review the methods used in cost-effectiveness analysis, the implications for cost-effectiveness findings, and the extent to which economic studies have influenced policy and program decisions. We discuss reasons for the relatively limited impact to date of economic evaluation in public health. Finally, we address the vexing question of how to decide which interventions are cost effective and worthy of funding. Policy makers have funded certain interventions with rather high cost-effectiveness ratios, notably nucleic acid testing for blood product safety. Cost-effectiveness estimates are a decision aid, not a decision rule.
Seasonality of Infectious Diseases
Authors: Fisman David N.
Published: March 2007

Seasonality, a periodic surge in disease incidence corresponding to seasons or other calendar periods, characterizes many infectious diseases of public health importance. The recognition of seasonal patterns in infectious disease occurrence dates back at least as far as the Hippocratic era, but mechanisms underlying seasonality of person-to-person transmitted diseases are not well understood. Improved understanding will enhance understanding of host-pathogen interactions and will improve the accuracy of public health surveillance and forecasting systems. Insight into seasonal disease patterns may be gained through the use of autocorrelation methods or construction of periodograms, while seasonal oscillation of infectious diseases can be easily simulated using simple transmission models. Models demonstrate that small seasonal changes in host or pathogen factors may be sufficient to create large seasonal surges in disease incidence, which may be important particularly in the context of global climate change. Seasonality represents a rich area for future research.
Electrogenic bicarbonate secretion by prairie dog gallbladder
Authors: Moser A. James , Gangopadhyay A. , Bradbury N. A. , Peters K. W. , Frizzell R. A. , Bridges R. J.
Published: March 2007

Pathological rates of gallbladder salt and water transport may promote the formation of cholesterol gallstones. Because prairie dogs are widely used as a model of this event, we characterized gallbladder ion transport in animals fed control chow by using electrophysiology, ion substitution, pharmacology, isotopic fluxes, impedance analysis, and molecular biology. In contrast to the electroneutral properties of rabbit and Necturus gallbladders, prairie dog gallbladders generated significant short-circuit current ( Isc; 171 ± 21 μA/cm2) and lumen-negative potential difference (−10.1 ± 1.2 mV) under basal conditions. Unidirectional radioisotopic fluxes demonstrated electroneutral NaCl absorption, whereas the residual net ion flux corresponded to Isc. In response to 2 μM forskolin, Iscexceeded 270 μA/cm2, and impedance estimates of the apical membrane resistance decreased from 200 Ω·cm2to 13 Ω·cm2. The forskolin-induced Iscwas dependent on extracellular HCO3−and was blocked by serosal 4,4′-dinitrostilben-2,2′-disulfonic acid (DNDS) and acetazolamide, whereas serosal bumetanide and Cl−ion substitution had little effect. Serosal trans-6-cyano-4-( N-ethylsulfonyl- N-methylamino)-3-hydroxy-2,2-dimethyl-chroman and Ba2+reduced Isc, consistent with the inhibition of cAMP-dependent K+channels. Immunoprecipitation and confocal microscopy localized cystic fibrosis transmembrane conductance regulator protein (CFTR) to the apical membrane and subapical vesicles. Consistent with serosal DNDS sensitivity, pancreatic sodium-bicarbonate cotransporter protein pNBC1 expression was localized to the basolateral membrane. We conclude that prairie dog gallbladders secrete bicarbonate through cAMP-dependent apical CFTR anion channels. Basolateral HCO3−entry is mediated by DNDS-sensitive pNBC1, and the driving force for apical anion secretion is provided by K+channel activation.
Optical mapping of Langendorff-perfused human hearts: establishing a model for the study of ventricular fibrillation in humans
Authors: Nanthakumar Kumaraswamy , Jalife José , Massé Stéphane , Downar Eugene , Pop Mihaela , Asta John , Ross Heather , Rao Vivek , Mironov Sergey , Sevaptsidis Elias , Rogers Jack , Wright Graham , Dhopeshwarkar Rajesh
Published: March 2007

Our objective was to establish a novel model for the study of ventricular fibrillation (VF) in humans. We adopted the established techniques of optical mapping to human ventricles for the first time to determine whether human VF is the result of wave breaks and singularity point formation and is maintained by high-frequency rotors and fibrillatory conduction. We describe the technique of acquiring optical signals in human hearts during VF, their characteristics, and the feasibility of possible analyses that could be performed to elucidate mechanisms of human VF. We used explanted hearts from five cardiomyopathic patients who underwent transplantation. The hearts were Langendorff perfused with Tyrode solution (95% O2-5% CO2), and the potentiometric dye di-4-ANEPPS was injected as a bolus into the coronary circulation. Fluorescence was excited at 531 ± 20 nm with a 150-W halogen light source; the emission signal was long-pass filtered at 610 nm and recorded with a mapping camera. Fractional change of fluorescence varied between 2% and 12%. Average signal-to-noise ratio was 40 dB. The mean velocity of VF wave fronts was 0.25 ± 0.04 m/s. Submillimetric spatial resolution (0.65–0.85 mm), activation mapping, and transformation of the data to phase-based analysis revealed reentrant, colliding, and fractionating wave fronts in human VF. On many occasions the VF wave fronts were as large as the entire vertical length (8 cm) of the mapping field, suggesting that there are a limited number of wave fronts on the human heart during VF. Phase transformation of the optical signals allowed the first demonstration ever of phase singularity point, wave breaks, and rotor formation in human VF. This method provides opportunities for potential analyses toward elucidation of the mechanisms of VF and defibrillation in humans.
Carboxyl-terminal and intracellular loop sites for CRF1receptor phosphorylation and β-arrestin-2 recruitment: a mechanism regulating stress and anxiety responses
Authors: Oakley Robert H. , Olivares-Reyes J. Alberto , Hudson Christine C. , Flores-Vega Fabiola , Dautzenberg Frank M. , Hauger Richard L.
Published: March 2007

The primary goal was to test the hypothesis that agonist-induced corticotropin-releasing factor type 1 (CRF1) receptor phosphorylation is required for β-arrestins to translocate from cytosol to the cell membrane. We also sought to determine the relative importance to β-arrestin recruitment of motifs in the CRF1receptor carboxyl terminus and third intracellular loop. β-Arrestin-2 translocated significantly more rapidly than β-arrestin-1 to agonist-activated membrane CRF1receptors in multiple cell lines. Although CRF1receptors internalized with agonist treatment, neither arrestin isoform trafficked with the receptor inside the cell, indicating that CRF1receptor-arrestin complexes dissociate at or near the cell membrane. Both arrestin and clathrin-dependent mechanisms were involved in CRF1receptor internalization. To investigate molecular determinants mediating the robust β-arrestin-2-CRF1receptor interaction, mutagenesis was performed to remove potential G protein-coupled receptor kinase phosphorylation sites. Truncating the CRF1receptor carboxyl terminus at serine-386 greatly reduced agonist-dependent phosphorylation but only partially impaired β-arrestin-2 recruitment. Removal of a serine/threonine cluster in the third intracellular loop also significantly reduced CRF1receptor phosphorylation but did not alter β-arrestin-2 recruitment. Phosphorylation was abolished in a CRF1receptor possessing both mutations. Surprisingly, this mutant still recruited β-arrestin-2. These mutations did not alter membrane expression or cAMP signaling of CRF1receptors. Our data reveal the involvement of at least the following two distinct receptor regions in β-arrestin-2 recruitment: 1) a carboxyl-terminal motif in which serine/threonine residues must be phosphorylated and 2) an intracellular loop motif configured by agonist-induced changes in CRF1receptor conformation. Deficient β-arrestin-2-CRF1receptor interactions could contribute to the pathophysiology of affective disorders by inducing excessive CRF1receptor signaling.
Inhibitory effects of intestinal electrical stimulation on food intake, weight loss and gastric emptying in rats
Authors: Yin Jieyun , Zhang Jing , Chen Jiande DZ
Published: March 2007

The aim was to investigate the effects of intestinal electrical stimulation (IES) on food intake, body weight, and gastric emptying in rats. An experiment on food intake and weight change was performed in 22 rats on a control diet and 10 diet-induced obese (DIO) rats for 4 wk with IES or sham IES. The effect of IES on gastric emptying was performed in another 20 rats in the control group. We found that 1) in control rats, 4-wk IES resulted in a reduction of 18.2% in the total amount of food intake compared with sham-IES ( P = 0.02); the rats treated with IES had a weight change of −1 ± 7.8g ( P = 0.03), which was equivalent to a weight loss of 6.2% due to IES when adjusted for normal growing. 2) Acute IES delayed gastric emptying by 20% in the control rats ( P < 0.01). 3) In the DIO rats, 1-wk IES with the same parameters as those used in the control rats resulted in a significant reduction in the total amount of food intake (126.6 ± 6.3 g vs. 116.9 ± 3.2 g, P < 0.01). More reduction in food intake was noted, and a significant weight change was also observed when stimulation energy was increased. 4) No adverse events were observed in any of the experiments. In conclusion, IES delays gastric emptying, reduces food intake, and decreases weight gain in control growing rats. These data suggest that it is worthy to explore therapeutic potentials of IES for obesity.
Lymphatic vessels transition to state of summation above a critical contraction frequency
Authors: Meisner Joshua K. , Stewart Randolph H. , Laine Glen A. , Quick Christopher M.
Published: March 2007

Although behavior of lymphatic vessels is analogous to that of ventricles, which completely relax between contractions, and blood vessels, which maintain a tonic constriction, the mixture of contractile properties can yield behavior unique to lymphatic vessels. In particular, because of their limited refractory period and slow rate of relaxation, lymphatic vessels lack the contractile properties that minimize summation in ventricles. We, therefore, hypothesized that lymphatic vessels transition to a state of summation when lymphatic vessel contraction frequency exceeds a critical value. We used an isovolumic, controlled-flow preparation to compare the time required for full relaxation with the time available to relax during diastole. We measured transmural pressure and diameter on segments of spontaneously contracting bovine mesenteric lymphatic vessels during 10 isovolumic volume steps. We found that beat-to-beat period (frequency−1) decreased with increases in diameter and that total contraction time was constant or slightly increased with diameter. We further found that the convergence of beat-to-beat period and contraction cycle duration predicted a critical transition value, beyond which the vessel does not have time to fully relax. This incomplete relaxation and resulting mechanical summation significantly increase active tension in diastole. Because this transition occurs within a physiological range, contraction summation may represent a fundamental feature of lymphatic vessel function.
Clofibrate causes an upregulation of PPAR-α target genes but does not alter expression of SREBP target genes in liver and adipose tissue of pigs
Authors: Luci Sebastian , Giemsa Beatrice , Kluge Holger , Eder Klaus
Published: March 2007

This study investigated the effect of clofibrate treatment on expression of target genes of peroxisome proliferator-activated receptor (PPAR)-α and various genes of the lipid metabolism in liver and adipose tissue of pigs. An experiment with 18 pigs was performed in which pigs were fed either a control diet or the same diet supplemented with 5 g clofibrate/kg for 28 days. Pigs treated with clofibrate had heavier livers, moderately increased mRNA concentrations of various PPAR-α target genes in liver and adipose tissue, a higher concentration of 3-hydroxybutyrate, and markedly lower concentrations of triglycerides and cholesterol in plasma and lipoproteins than control pigs ( P < 0.05). mRNA concentrations of sterol regulatory element-binding proteins (SREBP)-1 and -2, insulin-induced genes ( Insig) -1 and Insig-2, and the SREBP target genes acetyl-CoA carboxylase, 3-methyl-3-hydroxyglutaryl-CoA reductase, and low-density lipoprotein receptor in liver and adipose tissue and mRNA concentrations of apolipoproteins A-I, A-II, and C-III in the liver were not different between both groups of pigs. In conclusion, this study shows that clofibrate treatment activates PPAR-α in liver and adipose tissue and has a strong hypotriglyceridemic and hypocholesterolemic effect in pigs. The finding that mRNA concentrations of some proteins responsible for the hypolipidemic action of fibrates in humans were not altered suggests that there were certain differences in the mode of action compared with humans. It is also shown that PPAR-α activation by clofibrate does not affect hepatic expression of SREBP target genes involved in synthesis of triglycerides and cholesterol homeostasis in liver and adipose tissue of pigs.
Glycogen phosphorylase in glycogen-rich cells is involved in the energy supply for ion regulation in fish gill epithelia
Authors: Tseng Yung-Che , Huang Chang-Jen , Chang Joshua Chia-Hsi , Teng Wen-Yuan , Baba Otto , Fann Ming-Ji , Hwang Pung-Pung
Published: March 2007

The molecular and cellular mechanisms behind glycogen metabolism and the energy metabolite translocation between mammal neurons and astrocytes have been well studied. A similar mechanism is proposed for rapid mobilization of local energy stores to support energy-dependent transepithelial ion transport in gills of the Mozambique tilapia ( Oreochromis mossambicus). A novel gill glycogen phosphorylase isoform (tGPGG), which catalyzes the initial degradation of glycogen, was identified in branchial epithelial cells of O. mossambicus. Double in situ hybridization and immunocytochemistry demonstrated that tGPGG mRNA and glycogen were colocalized in glycogen-rich cells (GRCs), which surround ionocytes (labeled with a Na+-K+-ATPase antiserum) in gill epithelia. Concanavalin-A (a marker for the apical membrane) labeling indicated that GRCs and mitochondria-rich cells share the same apical opening. Quantitative real-time PCR analyses showed that tGPGG mRNA expression levels specifically responded to environmental salinity changes. Indeed, the glycogen content, glycogen phosphorylase (GP) protein level and total activity, and the density of tGPGG-expressing cells (i.e., GRCs) in fish acclimated to seawater (SW) were significantly higher than those in freshwater controls. Short-term acclimation to SW caused an evident depletion in the glycogen content of GRCs. Taken altogether, tGPGG expression in GRCs is stimulated by hyperosmotic challenge, and this may catalyze initial glycogen degradation to provide the adjacent ionocytes with energy to carry out iono- and osmoregulatory functions.
Co-Expression of Tyrosine Hydroxylase and GTP Cyclohydrolase I in Arginine Vasopressin-Synthesizing Neurons of the Human Supraoptic Nucleus Demonstrated by Laser Microdissection and Real-Time PCR
Authors: Kontostavlaki Dimitra P. , Panayotacopoulou Maria T. , Sluijs Jacqueline A. , Unmehopa Unga A. , Huitinga Inge , Hol Elly M. , Swaab Dick F.
Published: March 2007

Tyrosine hydroxylase (TH), the first and limiting enzyme for catecholamine synthesis, has been identified immunohistochemically (IHC) in human neurosecretory neurons where it is found to colocalize with vasopressin (AVP) or oxytocin. TH expression shows striking interindividual variability and appears to depend on neuronal activation. Since GTP cyclohydrolase I (GCHI), the first enzyme for tetrahydrobiopterin synthesis, the essential cofactor of TH, and aromatic L-amino acid decarboxylase (AADC) have so far not been detected in neurosecretory neurons, the functional role of TH in catecholamine synthesis is still questionable. Our purpose was to investigate in postmortem hypothalamus whether GCHI and AADC mRNAs are co-expressed with TH in human AVP-synthesizing neurons. Total RNA was extracted from laser microdissected TH-IHC-identified neurons as well as from dissected parts of the dorsolateral supraoptic nucleus (dl-SON) of 12 control subjects, i.e. without known neurological, psychiatric or endocrinological illness. GCHI, AADC and TH mRNA expression was determined by real-time PCR. Our results showed that GCHI mRNA is co-expressed with TH in almost all cases that had a considerable number of TH-immunoreactive (TH-IR) neurosecretory neurons. A positive correlation was found between TH-immunohistochemical intensity and the presence of GCHI mRNA. AADC mRNA expression was detected only in microdissected areas of dl-SON in 2 cases that showed an increased number of TH-IR neurons. The co-expression of GCHI with TH indicates that TH is indeed active in human neurosecretory neurons. The apparent limited expression of AADC indicates that dopamine might be produced in human neurosecretory neurons under activation of the hypothalamoneurohypophyseal system, although the possibility that L-dopa is the final product cannot be excluded.
Orexin A Induces GnRH Gene Expression and Secretion from GT1-7 Hypothalamic GnRH Neurons
Authors: Sasson Ravid , Dearth Robert K. , White Rachel S. , Chappell Patrick E. , Mellon Pamela L.
Published: March 2007

Orexin A, a recently discovered hypothalamic peptide, has been shown to have a stimulatory effect on release of gonadotropin-releasing hormone (GnRH) from rat hypothalamic explants in vitro. However, it is presently unclear whether in vivo this effect is mediated directly at the level of the GnRH neuron, or via multiple afferent neuronal connections. Therefore, in the present study, we investigated the direct action of orexin A on GnRH neurons using the immortalized GnRH-secreting GT1-7 hypothalamic cells. Orexin-1 receptor (OX1R) expression was detected in GT1-7 cells by RT-PCR and Western blot. Results showed that 0.1–1 nM orexin A, when administered in culture media for 4 h, can significantly stimulate GnRH mRNA expression in GT1-7 cells (p < 0.05). Administration of 1 µM OX1R antagonist, SB-334867, completely blocked the observed orexin A responses in these cells, indicating that orexin A stimulation of GnRH neurons is specifically through OX1R. Moreover, 0.1 nM orexin A stimulated GnRH release after 30–45 min. To examine possible signal transduction pathways involved in mediating these effects, a MEK inhibitor (UO-126), PKC inhibitor (calphostin C), and PKA inhibitor (H-89), were used, with each blocking orexin A-induced GnRH transcription and release from immortalized cells. Collectively, our results show that orexin A is capable of directly stimulating GnRH transcription and neuropeptide release from these immortalized hypothalamic neurons, and that the effects of orexin A appear to be mediated via the OX1R, coupled with activation of the PKC-, MAPK- and PKA-signaling pathways. It is suggested that the stimulatory effect of orexin A on GnRH transcription and release may also occur directly at the level of GnRH neurons in vivo.
Regulation of the Hypothalamic Melanin-Concentrating Hormone Neurons by Sex Steroids in the Goldfish: Possible Role in the Modulation of Luteinizing Hormone Secretion
Authors: Cerdá-Reverter José Miguel , Canosa Luis Fabian , Peter Richard Ector
Published: March 2007

In teleost fish, melanin-concentrating hormone (MCH) is a cyclic heptadecapeptide released from the pituitary during white background adaptation. In the periphery MCH concentrates melanin granules in melanophores thus lightening the body color of fish. Evidence from mammalian studies has demonstrated the involvement of MCH in the control of energy balance and the reproductive axis. Information about the hormonal regulation of MCH neurons in non-mammalian systems is scarce and nothing is known about its role in the regulation of the reproductive axis. We here report the molecular characterization of two MCH precursors in the goldfish. Both precursors are peripherally expressed and the expression in the central nervous system is restricted to the mediobasal hypothalamus. Hypothalamic MCH-mRNA production is upregulated during white background adaptation. Both testosterone and estradiol stimulate MCH mRNA expression in the hypothalamus in a sex-dependent manner, with females showing the greatest responsiveness. In addition, in vitroexperiments demonstrated that graded doses of salmon MCH stimulate LH, but not GH, secretion from dispersed pituitary cells. Results suggest that hypothalamic MCH may participate in the steroid positive feedback loop on pituitary LH secretion.
Human Articular Chondrocytes – Plasticity and Differentiation Potential
Authors: Tallheden Tommi , Brittberg Mats , Peterson Lars , Lindahl Anders
Published: March 2007

Articular cartilage has no or very low ability of self-repair, and untreated lesions may lead to the development of osteoarthritis. One method which has been proven to result in long-term repair of isolated lesions is autologous chondrocyte transplantation. In this method, culture-expanded chondrocytes isolated from full-thickness biopsies, taken from a non-weight-bearing area at the supromedial edge of the femoral condyle, are transplanted back to the patient under a cover of periosteum. The treatment is able to regenerate hyaline cartilage with long-term durability. Although the repair mechanism behind this treatment has not been fully elucidated, emerging data generated by microarray technologies reveal an interesting regeneration process involving cellular and molecular mechanisms found during fetal development. In hyaline cartilage, the human chondrocyte population is generally considered a homogenous cell population, but recently several investigators have demonstrated that cells isolated from human articular cartilage have stem cell properties and that the superficial layer contains such cells. This paper will discuss these recent data and their implications for future treatment strategies aiming to induce regeneration in articular cartilage surfaces.
Homologous Activated Platelets Stimulate Differentiation and Proliferation of Primary Human Bone Cells
Authors: Clausen Christian , Hermund Niels Ulrich , Donatsky Ole , Nielsen Henrik , Osther Kurt
Published: March 2007

In bone tissue engineering approaches the expansion of bone cells is an essential part. In recent years the search for an appropriate alternative to fetal bovine serum (FBS) in the ex vivo expansion process has increased. This study demonstrates that platelet-rich clot releasate (PRCR) could be an appropriate alternative. The effects of PRCR on bone cell cultures derived from 5 different human donors were analyzed with respect to morphology, proliferation, apoptosis and gene expression. Five different PRCR concentrations were used: 1, 5, 10, 20 and 40%. The population doubling (PD) values were calculated for each concentration. Light microscopy analysis was done after 3 and 9 days. Flow cytometry was used to analyze cell cycle effects. The gene expression of alkaline phosphatase, collagen type 1, osteocalcin, bone sialoprotein and osteopontin was analyzed with RT-PCR. 10% FBS cultures were used as controls. With 10% PRCR the cell morphology resembled the control cultures; however, the PD values were significantly higher (p < 0.01). Concentrations of 20 and 40% had a clear cytotoxic effect, observed with light microscopy analysis and flow cytometry. PRCR had a potent effect on the expression of osteogenic markers and resulted in a concentration-dependent upregulation. We demonstrate that human bone cells derived from the maxillary alveolar ridge can be cultured in medium containing PRCR instead of FBS. The addition of PRCR results in higher proliferative capacity and upregulation of osteogenic markers. These results indicate that FBS could be avoided in future tissue engineering approaches using bone cells from this anatomic site.
Delayed Formation of Actin Filaments in the Outer Pillar Head Plate of VASP–/– Mice
Authors: Schick Bernhard , Starlinger Veronika , Häberle Lothar , Eigenthaler Martin , Walter Ulrich , Knipper Marlies
Published: March 2007

Pillar cells with their rich network of tubulin and actin filaments have been reported to contribute to the rigidity of the organ of Corti. As the earliest expression of the actin filament enhancer vasodilator-stimulated phosphoprotein (VASP) in the outer pillar head plate has been found to be associated with the onset of hearing, we tested hearing development in VASP–/– compared to wild-type mice. Performing measurements of auditory brainstem responses on postnatal days (P) P14 and P21, we detected statistically significantly higher thresholds in VASP–/– compared to wild-type mice at P14, but no hearing differences at P21. Staining for prestin and synaptophysin at P12 in morphologically regularly developed cochleae of VASP–/– mice provided an immature prestin protein pattern but no evidence of developmental delay in hair cell innervations. Regularly intense staining of actin filaments in the outer pillar head plate was found only in wild-type but not in VASP–/– mice at P14. At P21, intensive actin filament staining was also observed in the outer pillar head plates of VASP–/– mice. The delayed hearing development in VASP–/– mice is supposed to be caused by a delayed formation of actin filaments in the outer pillar head plate indicating the importance of appropriate pillar cell stiffness in cochlear mechanics.
Vasopressin-Containing Neurons of the Hypothalamic Parvocellular Paraventricular Nucleus of the Jerboa: Plasticity Related to Immobilization Stress
Authors: Barakat Y. , Pape J.R. , Boutahricht M. , El Ouezzani S. , Alaoui A. , Chaigniau M. , Barakat L. , Tramu G. , Mâgoul R.
Published: March 2007

The corticotropin-releasing hormone (CRH) neurons of the hypothalamic parvocellular paraventricular nucleus (PVN) have a high potential for phenotypical plasticity, allowing them to rapidly modify their neuroendocrine output, depending upon the type of stressors. Indeed, these neurons coexpress other neuropeptides, such as cholecystokinin (CCK), vasopressin (VP), and neurotensin, subserving an eventual complementary function to CRH in the regulation of the pituitary. Unlike in rats, our previous data showed that in jerboas, CCK is not coexpressed within CRH neurons in control as well as stressed animals. The present study explored an eventual VP participation in the phenotypic plasticity of CRH neurons in the jerboa. We analyzed the VP expression within the PVN by immunocytochemistry in male jerboas submitted to acute stress. Our results showed that, contrary to CRH and CCK, no significant change concerned the number of VP-immunoreactive neurons following a 30-min immobilization. The VP/CRH coexpression within PVN and median eminence was investigated by double immunocytochemistry. In control as well as stressed animals, the CRH-immunopositive neurons coexpressed VP within cell bodies and terminals. No significant difference in the number of VP/CRH double-labeled cells was found between both groups. However, such coexpression was quantitatively more important into the posterior PVN as compared with the anterior PVN. This suggests an eventual autocrine/paracrine or endocrine role for jerboa parvocellular VP which is not correlated with acute immobilization stress. VP-immunoreactive neurons also coexpressed CCK within PVN and median eminence of control and stressed jerboas. Such coexpression was more important into the anterior PVN as compared with the posterior PVN. These results showed the occurrence of at least two VP neuronal populations within the jerboa PVN. In addition, the VP expression did not depend upon acute immobilization stress. These data highlight differences in the neuroendocrine regulatory mechanisms of the stress response involving CRH/CCK or VP. They also underline that adaptative physiological mechanisms to stress might vary from one mammal species to another.
Accuracy of Prenatal Diagnosis of Congenital Heart Disease with Fetal Echocardiography
Authors: Bakiler Ali Rahmi , Ozer Esra Arun , Kanik Ali , Kanit Hakan , Aktas Fatma Nur
Published: March 2007

Objective: To study the diagnostic value of fetal echocardiography in detecting congenital heart disease (CHD) during the prenatal period. Methods: One hundred and ninety-seven pregnant women with a high risk of prenatal CHD of their fetuses were included in this study. The fetal heart was scanned with echocardiography, performing complete evaluation of the cardiac system. The prenatal echocardiographic findings were correlated with postnatal echocardiography results or autopsy findings, if the pregnancy was terminated or the fetus died in utero. Results: 10 of the 197 fetuses showed CHD by fetal echocardiography, whereas postnatal echocardiography and postmortem examination revealed cardiac abnormalities in 21 patients. Of those, 7 (41.1%) had the most common referral indication, i.e., cardiac abnormality, found on routine ultrasound examination. Specificity and sensitivity of fetal echocardiography for cardiac abnormalities were found to be 98 and 42%, respectively. The positive predictive value of echocardiography was 90% and the negative predictive value 93%. Conclusions: We conclude that fetal echocardiography is a reliable tool for prenatal diagnosis in experienced hands. Pediatric cardiologists should be more aware while performing fetal echocardiography in patients referred by obstetricians for CHD.
Plasma Cysteine Concentrations in Uncomplicated Pregnancies
Authors: Viskova H. , Vesela K. , Janosikova B. , Krijt J. , Visek J.A. , Calda P.
Published: March 2007

Objective: To measure levels of total plasma cysteine, homocysteine, cysteinylglycine and glutathione of normotensive primiparous pregnant women in the second and the third trimester. Methods: Two consecutive blood samples were taken from 65 healthy primiparous women in the 19th to 21st weeks of pregnancy and then in the 30th to 32nd weeks. Plasma total cysteine, homocysteine, cysteinylglycine and glutathione were determined by HPLC method. Women were followed until delivery. Sixty-two pregnant women were normotensive throughout the pregnancy and 3 developed pre-eclampsia. Median levels of thiols in the second and the third trimesters were compared using paired t test. Results: Levels (median [range], µmol/l) of plasma total cysteine in normotensive pregnant women were significantly lower in the third than in the mid-trimester (176.1 [163.0, 189.4] vs. 187.4 [178.7, 205.2], p < 0.001). Concentrations of total homocysteine, cysteinylglycine and glutathione were not different. Conclusion: Plasma total cysteine (t-Cys) is significantly lower in the third compared to the second trimester. Urinary excretion of t-Cys does not differ in the second compared to the third trimester. The decrease of t-Cys might indicate that cysteine is essential for the fetus.
Prenatal and Postnatal Management of a Patient with Pentalogy of Cantrell and Left Ventricular Aneurysm
Authors: Grethel Erich J. , Hornberger Lisa K. , Farmer Diana L.
Published: March 2007

Introduction: Omphalocele is often associated with cardiac diverticulum in the pentalogy of Cantrell, however a prenatal diagnosis of omphalocele has not been described with a broad-based, thin-walled aneurysm of the ventricular wall in a surviving patient. Case Report: A case of omphalocele with Morgagni hernia and left ventricular aneurysm diagnosed at 21 weeks, 6 days’ gestational age is reported. Initial ultrasound examination demonstrated the cardiac defect and subsequent ultrasounds revealed the abdominal wall defect. Prenatal monitoring included serial ultrasound and echocardiography. A viable fetus was delivered via cesarean section at 37 weeks’ gestational age. The omphalocele and Morgagni hernia were repaired on the infant’s 4th day of life. The cardiac defect continues to be monitored with echocardiography at 15 months of age. Discussion: The case is discussed along with a short review of the literature of midline thoracoabdominal defects and left ventricular apical aneurysms.
Gastroschisis with Fetal Chromosomal Abnormality: A Case Report
Authors: Guler Ismail , Erdem Ahmet , Biri Aydan , Gunaydin Guven , Yilmaz Ercan , Erdem Mehmet , Karaoguz Meral Yirmibeş
Published: March 2007

Gastroschisis is a rare anomaly and it is usually not associated with other syndromic or nonsyndromic anomalies. The first case of gastroschisis with aneuploidy (Turner syndrome) is presented. A fetal huge cystic hygroma was diagnosed by prenatal sonography at 12 weeks of pregnancy and chorionic villi sampling (CVS) was performed. Cytogenetic analysis revealed 45, X0. The pregnancy was terminated by induction of labor at 16 weeks of pregnancy. The female fetus had a big membrane of cystic hygroma surrounding the fetal neck. Additionally, a full abdominal thickness defect with multiple loops of bowel outside the abdomen, which could not be diagnosed on prenatal ultrasound scan, was detected on postnatal examination.
Maternal Serum Transformed α-Fetoprotein Levels in Women with Intrauterine Growth Retardation
Authors: Bartha Jose L. , Illanes Sebastian , González-Bugatto Fernando , Abdel-Fattah Sherif A. , Mizejewski Gerald J. , Soothill Peter W.
Published: March 2007

Objective: To evaluate maternal serum transformed α-fetoprotein (t-AFP) levels in women with intrauterine growth retardation (IUGR). Methods: 60 pregnant women in two groups were studied: 30 with IUGR and 30 healthy pregnant women as a control group. t-AFP concentrations were determined by ELISA assay. Results: Maternal serum t-AFP levels were higher in women with IUGR than in the control group: 15.39 (10.81–24.01) ng/ml vs. 8.66 (6.22–13.45) ng/ml (p = 0.003). t-AFP levels were even higher in those with fetal hemodynamic redistribution 21.08 (16.02–40.85) ng/ml than in those without 12.15 (10.48–17.45) ng/ml (p = 0.03). Conclusions: Maternal serum t-AFP is increased in women with IUGR and this elevation is marked in those with fetal hemodynamic redistribution.
Nonimmune Hydrops Fetalis Diagnosed during the Second Half of Pregnancy in Southern China
Authors: Liao Can , Wei Jiaxue , Li Qiuming , Li Jian , Li Lixian , Li Dongzhi
Published: March 2007

Objective: To analyze the etiologies of nonimmune hydrops fetalis (NIHF) for a southern section of China. Methods: 138 cases of NIHF presenting after 20 weeks’ gestation over a 10-year period were reviewed. Results: The causes of fetal hydrops were identified in 92.0%. Homozygous α-thalassemia dominated as the cause of NIHF (55.1%), followed by infection (15.2%) and structural abnormalities (10.9%). No obvious cause was identified in 11 cases (8.0%). Termination of pregnancy was performed in 131 cases. Conclusions: Homozygous α-thalassemia is the most common cause of NIHF in southern China. An effective prenatal thalassemia screening program should be established in this high prevalence region.
De novo Subtelomeric Deletion Additional to an Inherited Apparently Balanced Reciprocal Translocation
Authors: Delahaye A. , Pipiras E. , Kanafani S. , Touboul C. , Vergnaud A. , Encha-Razavi F. , Sinico M. , Benkhalifa M. , Kasakyan S. , Serero S. , Wolf J.P. , Gérard-Blanluet M. , Benzacken B.
Published: March 2007

Objective: We describe the analysis of an apparently balanced inherited reciprocal translocation in a fetus presenting with multiple congenital abnormalities, characterize the structural chromosome rearrangement, and report an unexpected additional imbalance to the inherited rearrangement. Methods: DNA microarray was used to screen for genomic imbalance in subtelomeric and interstitial critical regions. High-resolution comparative genomic hybridization was used to screen for genomic imbalance at a genome-wide level. Fluorescence in situ hybridization using whole-chromosome painting and specific probes was used to characterize the inherited translocation, and the size of the de novoadditional deletion. Results: An unexpected additional deletion was found in 7qter on derivative 10 of the inherited maternal reciprocal translocation t(7;10)(q11.23; p14). Conclusions: We show the usefulness of genome-wide and specific molecular cytogenetic techniques to explore apparently balanced rearrangements.