bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Regulation of Prostate Blood Flow by Vascular Endothelial Growth Factor and Its Participation in the Androgenic Regulation of Prostate Blood Flow in Vivo
Authors: Shibata Yasuhiro , Kashiwagi Bunzo , Arai Seiji , Fukabori Yoshitatsu , Suzuki Kazuhiro , Honma Seijiro , Yamanaka Hidetoshi 
Published: July 2004

Abstract
Previous studies on prostate blood flow regulation have indicated that androgen regulates prostate blood flow. However, the mechanism responsible for this regulation is unknown. In the present study, we focused on the effects of vascular endothelial growth factor (VEGF), a key factor responsible for angiogenesis and androgenic blood flow regulation. We examined in vivo the effect of VEGF on prostate blood flow and its participation in the androgenic regulation of this blood flow using a castrated rat model following subcapsular intraprostatic injection method. We found that VEGF is involved in blood flow regulation with an activity equal to that of dihydrotestosterone (DHT). The effect of VEGF on prostate blood flow was already seen at 30 min after the administration. The elevating effect of DHT on castrated rat prostate blood flow was abolished by coadministration of DHT with neutralizing anti-VEGF antibody. The change in VEGF-A mRNA expression in response to androgen stimulation was examined by double-fluorescent probe quantitative PCR (Taqman PCR). The results showed that androgenic regulation of VEGF gene expression occurred shortly after androgen stimulation. VEGF gene up-regulation was abolished or down-regulated by coadministration of neutralizing anti-VEGF antibody. This is the first report on the importance of VEGF in the androgenic regulation signaling pathway that affects prostate blood flow. Alternative treatment targeted toward anti-VEGF activity as a substitute for ordinary antiandrogenic therapy may be effective against prostate diseases, especially those with androgen-independent and hyperhemorrhagic status.
Minireview: Developmental Regulation of Thyrotropin Receptor Gene Expression in the Fetal and Newborn Thyroid
Authors: Brown Rosalind S. 
Published: July 2004

AbstractThe TSH receptor plays a pivotal role in thyroid gland growth, function, and differentiation in the mature animal, but only recently has its role in the fetus and neonate been examined. Observational studies comparing the developmental regulation of TSH receptor gene expression, with thyroid morphology, and thyroid-specific gene expression in the rodent model, are reviewed in the context of older literature. Together, these data strongly suggest that the TSH receptor is essential for terminal thyroid maturation and growth but is not involved in early thyroid organogenesis or migration. Consistent with the aforementioned studies in rodents, babies with a loss of function mutation of the TSH receptor as well as babies born to mothers with potent TSH receptor-blocking antibodies have hypothyroidism and hypoplastic, but normally located, thyroid glands. Because the TSH receptor is probably not expressed in human fetuses before 10–12 wk gestation when thyroid organogenesis and migration are complete, these data provide strong evidence that human chorionic gonadotropin, which peaks in the first trimester of human pregnancy, could not play a role in fetal thyroid development. Similarly, these data imply strongly that maternal TSH receptor antibodies, when present in high titer, are of major importance in influencing fetal thyroid function only after mid-pregnancy when, by analogy with rodents, increased TSH receptor expression is likely to occur.
Formation of Cystic Ovarian Follicles Associated with Elevated Luteinizing Hormone Requires Estrogen Receptor-β
Authors: Couse John F. , Yates Mariana M. , Sanford Ryan , Nyska Abraham , Nilson John H. , Korach Kenneth S. 
Published: July 2004

Abstract
Stringent regulation of LH secretion from the pituitary is vital to ovarian function in mammals. Two rodent models of LH hypersecretion are the transgenic LHβ-C-terminal peptide (LHβCTP) and estrogen receptor-α (ERα)-null (αERKO) mice. Both exhibit ovarian phenotypes of chronic anovulation, cystic and hemorrhagic follicles, lack of corpora lutea, interstitial/stromal hyperplasia, and elevated plasma estradiol and testosterone. Because ERβ is highly expressed in granulosa cells of the ovary, we hypothesized the intraovarian actions of ERβ may be necessary for full manifestation of phenotypes associated with LH hyperstimulation. To address this question, we generated female mice that possess elevated LH, but lack ERβ, by breeding the LHβCTP and ERβ-null (βERKO) mice. A comparison of LHβCTP, αERKO, and βERKOLHCTP females has allowed us to elucidate the contribution of each ER form to the pathologies and endocrinopathies that occur during chronic LH stimulation of the ovary. αERKO ovaries respond to elevated LH by exhibiting an amplified steroidogenic pathway characteristic of the follicular stage of the ovarian cycle, whereas wild-typeLHCTP and βERKOLHCTP females exhibit a steroidogenic profile more characteristic of the luteal stage. In addition, the hemorrhagic and cystic follicles of the LHβCTP and αERKO ovaries require the intraovarian actions of ERβ for manifestation, because they were lacking in the βERKOLHCTP ovary. In turn, ectopic expression of the Leydig cell-specific enzyme, Hsd17b3, and male-like testosterone synthesis in the αERKO ovary are unique to this genotype and are therefore the culmination of elevated LH and the loss of functional ERα within the ovary.
Expression of Brain-Derived Neurotrophic Factor and Its Receptors in the Median Eminence Cells with Sensitivity to Stress
Authors: Givalois Laurent , Arancibia Sandor , Alonso Gérard , Tapia-Arancibia Lucia 
Published: July 2004

Abstract
The median eminence (ME) is considered as the final common pathway connecting the nervous and endocrine systems. In this neurohemal structure, dynamic interactions among nerve terminals, tanycytes, and astrocytes determine through plastic processes the neurohormones access to the portal blood. Because brain-derived neurotrophic factor (BDNF) is involved in plastic changes, we investigated its presence and that of its receptors (TrkB) in the different cellular types described in the ME. Using in situ hybridization and immunohistochemical techniques, we demonstrated that BDNF immunoreactivity was essentially located in the astrocytes and to a lesser extent in tanycytes. By contrast, BDNF was not detected in nerve terminals reaching the external layer of the ME. TrkB antibodies recognizing the extracellular receptor domain labeled all of these different cell types, suggesting an autocrine or paracrine action of BDNF at this level. More selective antibodies showed that TrkB.FL immunostaining was found in tanycytes and nerve endings, whereas TrkB.T1 immunostaining was localized in all cellular types. Immobilization stress increased BDNF mRNA and BDNF immunoreactivity patterns and induced biphasic BDNF release from the ME, as analyzed by push-pull perfusion. In addition, we observed that 60-min stress intensified BDNF immunoreactivity in the internal layer and also its colocalization with glial fibrillary acidic protein. Stress also accentuated BDNF immunostaining in the perivascular space in elements that were not labeled with antibodies recognizing fibroblast or endothelial cells. These data disclosed a novel location of BDNF and its receptors in the ME, which are presumably involved in dynamic processes such as hormone release.
Altered Growth in Male Peroxisome Proliferator-Activated Receptor γ (PPARγ) Heterozygous Mice: Involvement of PPARγ in a Negative Feedback Regulation of Growth Hormone Action
Authors: Rieusset Jennifer , Seydoux Josiane , Anghel Silvia I. , Escher Pascal , Michalik Liliane , Soon Tan Nguan , Metzger Daniel , Chambon Pierre , Wahli Walter , Desvergne Béatrice 
Published: July 2004

AbstractThe peroxisome proliferator-activated receptor γ (PPARγ) plays a major role in fat tissue development and physiology. Mutations in the gene encoding this receptor have been associated to disorders in lipid metabolism. A thorough investigation of mice in which one PPARγ allele has been mutated reveals that male PPARγ heterozygous (PPARγ +/−) mice exhibit a reduced body size associated with decreased body weight, reflecting lean mass reduction. This phenotype is reproduced when treating the mice with a PPARγ- specific antagonist. Monosodium glutamate treatment, which induces weight gain and alters body growth in wild-type mice, further aggravates the growth defect of PPARγ +/− mice. The levels of circulating GH and that of its downstream effector, IGF-I, are not altered in mutant mice. However, the IGF-I mRNA level is decreased in white adipose tissue (WAT) of PPARγ +/− mice and is not changed by acute administration of recombinant human GH, suggesting an altered GH action in the mutant animals. Importantly, expression of the gene encoding the suppressor of cytokine signaling-2, which is an essential negative regulator of GH signaling, is strongly increased in the WAT of PPARγ +/− mice. Although the relationship between the altered GH signaling in WAT and reduced body size remains unclear, our results suggest a novel role of PPARγ in GH signaling, which might contribute to the metabolic disorder affecting insulin signaling in PPARγ mutant mice.
Hypergravity from conception to adult stage: effects on contractile properties and skeletal muscle phenotype
Authors: Bozzo Cyril , Stevens Laurence , Bouet Valentine , Montel Valérie , Picquet Florence , Falempin Maurice , Lacour Michel , Mounier Yvonne 
Published: July 2004

SUMMARYThis study examined the effects of an elevation of the gravity factor(hypergravity – 2 g) on the molecular and functional characteristics of rat soleus and plantaris muscles. Long Evans rats were conceived, born and reared (CBR) continuously in hypergravity conditions until the age of 100 days. Whole muscle morphological parameters, Ca2+activation characteristics from single skinned fibers, troponin (Tn) subunit and myosin heavy (MHC) and light (MLC) chains isoform compositions were examined in CBR and control muscles from age-paired terrestrial rats. Decreases in body and muscle mass in soleus and plantaris muscles were observed and associated, in the soleus, with a decrease in fiber diameter. The specific force of CBR soleus fibers was increased, and correlated with the elevation of Ca2+ affinity. This was accompanied by slow-to-slower TnC and TnI isoform transitions and a rearrangement in TnT fast isoform content. The MHC transformations of the soleus after hypergravity were associated with the up (down)-regulation of the MHCI (MHCIIa) mRNA isoforms. The MLC2 phosphorylation state remained unchanged in the soleus muscle. The results suggested that the gravity factor could interact with rat muscle development and that hypergravity experiments could provide good tools for the study of myofibrillar protein plasticity and their associated pathways of regulation.
Thedg2 (for)gene confers a renal phenotype inDrosophilaby modulation of cGMP-specific phosphodiesterase
Authors: MacPherson Matthew R. , Broderick Kate E. , Graham Shirley , Day Jonathan P. , Houslay Miles D. , Dow Julian A. T. , Davies Shireen A. 
Published: July 2004

SUMMARYFluid transport in Drosophila melanogaster tubules is regulated by guanosine 3′,5′-cyclic monophosphate (cGMP) signalling. Here we compare the functional effects on tubules of different alleles of the dg2 (foraging or for) gene encoding a cGMP-dependent protein kinase (cGK), and show that the fors allele confers an epithelial phenotype. This manifests itself as hypersensitivity of epithelial fluid transport to the nitridergic neuropeptide, capa-1, which acts through nitric oxide and cGMP. However, there was no significant difference in tubule cGK activity between fors and forR adults. Nonetheless, fors tubules contained higher levels of cGMP-specific phosphodiesterase (cG-PDE) activity compared to forR. This increase in cGMP-PDE activity sufficed to decrease cGMP content in fors tubules compared to forR. Challenge of tubules with capa-1 increases cGMP content in both fors and forR tubules, although the increase from resting cGMP levels is greater in forstubules. Capa-1 stimulation of tubules reveals a potent inhibition of cG-PDE in both lines, although this is greater in fors; and is sufficient to explain the hypersensitive transport phenotype observed.Thus, polymorphisms at the dg2 locus do indeed confer a cGMP-dependent transport phenotype, but this can best be ascribed to an indirect modulation of cG-PDE activity, and thence cGMP homeostasis, rather than a direct effect on cGK levels.
Heat induced male sterility inDrosophila melanogaster: adaptive genetic variations among geographic populations and role of the Y chromosome
Authors: Rohmer Céline , David Jean R. , Moreteau Brigitte , Joly Dominique 
Published: July 2004

SUMMARYWe analyzed genetic variation among geographically diverse populations of Drosophila and showed that tropical flies are more tolerant than temperate ones to heat-induced male sterility, as assessed by the presence of both motile sperm and progeny production. In tropical populations, the temperature inducing 50% sterility (median threshold) is 1°C above the value for temperate populations (30.4 vs. 29.4°C). When transferred to a mild permissive temperature (21°C), males recover fertility. Recovery time is proportional to pre-adult culture temperature. At these temperatures, recovery time is greater for temperate than for tropical populations. Crosses between a temperate and a tropical strain (F1,F2 and successive backcrosses) revealed that the Y chromosome was responsible for much of the geographic variation. Sterile males exhibited diverse abnormalities in the shape and position of sperm nuclei. However,impairment of the spermatid elongation seems to be the major factor responsible for sperm inviability. Heat-induced male sterility seems to be quite a general phenomenon in Drosophilid species and variation of threshold temperatures may be important for explaining their geographic distributions.
Extracellular H+ dynamics during oogenesis inRhodnius prolixusovarioles
Authors: Bjornsson C. S. , Huebner E. 
Published: July 2004

SUMMARYThe spatiotemporal dynamics of transmembrane hydrogen ion (H+)fluxes during oogenesis were investigated in the telotrophic ovarioles of the insect, Rhodnius prolixus. Although Rhodnius ovarioles possess exaggerated morphological and electrical polarity between nurse cells and oocytes, little is known about H+ changes during oogenesis,despite the regulatory role played by H+ and pH in many relevant cellular processes. A number of dynamic extracellular H+ fluxes were measured along Rhodnius ovarioles, representing an oogenesis cycle, using a non-invasive, self-referencing, H+-selective probe. The interfollicular stalk separating adjacent follicles exhibited prominent H+ efflux that peaked during midvitellogenesis and declined during late vitellogenesis. H+ efflux in this region preceded stalk formation and, importantly, preceded the onset of vitellogenesis in the adjacent posterior follicle. H+ efflux was also observed over the terminal follicle, where specialized regions of the chorion were forming, and was still detected around follicle cells after ovulation, indicating that the somatic follicular epithelium produced this flux. Transmembrane H+fluxes may drive intracellular pH changes or may stabilize pHi in response to pH-altering events. H+ fluxes may play a role in processes that coincide spatially and temporally, including the onset of vitellogenesis, endocytosis, follicle cell cytoskeletal dynamics, and regulation of interfollicular feedback mechanisms.
Immune response to fleas in a wild desert rodent: effect of parasite species, parasite burden, sex of host and host parasitological experience
Authors: Khokhlova Irina S. , Spinu Marina , Krasnov Boris R. , Degen A. Allan 
Published: July 2004

SUMMARYWe studied immune responses of the jird Meriones crassus to different flea species belonging to the same family. We used jirds maintained in an outdoor enclosure (enclosure; N=18) and parasitized by fleas Xenopsylla conformis mycerini and Xenopsylla ramesis, and also jirds born in the laboratory to previously parasitized mothers(laboratory animals; N=23). We asked (i) whether cross-immunity to different fleas occurs, (ii) whether there is a sex difference in immune responses to flea parasitism and (iii) whether the severity of the immune responses depends on parasite load. In the enclosure animals, immune response to antigen from the unfamiliar flea Synosternus cleopatrae pyramidisdid not differ from those to antigens from the familiar fleas. In contrast,laboratory rodents demonstrated no difference in the immune response between S. c. pyramidis antigen and either the phytohemagglutinin treatment or controls, although their responses to antigens of fleas familiar to their mothers (X. c. mycerini and X. ramesis) were significantly higher than those to antigen of S. c. pyramidis and phytohemagglutinin. The results clearly demonstrated that (i) cross-reactivity in rodent responses to different flea species occurred for enclosure but not for laboratory jirds and (ii) immune-naïve animals whose mothers were parasitized by fleas had some degree of immunity against fleas. The only sex difference in immunological parameters was the higher level of circulating immune complexes in females than in males. Only phagocytic activity was affected by flea burden, decreasing with an increase in flea numbers.
Scaling of jaw muscle size and maximal bite force in finches
Authors: van der Meij M. A. A. , Bout R. G. 
Published: July 2004

SUMMARYFringillids and estrildids differ in their husking performance on hard closed-shelled seeds, which are cracked before they are eaten. The time required to husk a seed is directly related to seed hardness, and husking time is therefore expected to be related to bite force as well. We investigated whether there is a significant difference in jaw muscle mass and maximal bite force between fringillids and estrildids. The analysis shows that fringillids have relatively larger jaw muscles than estrildids and are able to produce higher bite forces than estrildids of the same body size. This difference in jaw muscle mass mainly results from a difference in jaw closing muscles. Compared with other birds, the jaw muscles of both fringillids and estrildids scale strongly positively allometric with body size. Muscle fibre length scales negatively allometric with body size, which results in relatively high muscle and bite forces. Comparison with the scarce data available for other trophic groups suggests that the scaling of jaw muscle size depends on diet and that jaw muscle size in finches is an adaptation to their feeding behaviour.
Fiber polymorphism in skeletal muscles of the American lobster,Homarus americanus: continuum between slow-twitch (S1) and slow-tonic (S2) fibers
Authors: Medler Scott , Lilley Travis , Mykles Donald L. 
Published: July 2004

SUMMARYIn recent years, an increasing number of studies has reported the existence of single fibers expressing more than one myosin heavy chain (MHC) isoform at the level of fiber proteins and/or mRNA. These mixed phenotype fibers, often termed hybrid fibers, are currently being recognized as the predominant fiber type in many muscles, and the implications of these findings are currently a topic of great interest. In a recent study, we reported single fibers from the cutter claw closer muscle of lobsters that demonstrated a gradation between the slow-twitch (S1) and slow-tonic (S2) muscle phenotype. In the present study, we focused on S1 and S2fibers from the superficial abdominal muscles of the lobster as a model to study the continuum among muscle fiber types. Complementary DNAs (cDNA)encoding an S2 isoform of myosin heavy chain (MHC) and an S2 isoform of tropomyosin (Tm) were isolated from the superficial abdominal flexor muscles of adult lobsters. These identified sequences were used to design PCR primers used in conjunction with RT-PCR and real-time PCR to measure expression levels of these genes in small muscle samples and single fibers. The relative expression of the corresponding S1 MHC and S1 Tm isoforms was measured in the same samples with PCR primers designed according to previously identified sequences. In addition, we measured the relative proportions of MHC, troponin (Tn) T and I protein isoforms present in the same samples to examine the correlation of these proteins with one another and with the MHC and Tm mRNAs. These analyses revealed significant correlations among the different myofibrillar proteins,with the S1 and S2 fibers being characterized by a whole assemblage of myofibrillar isoforms. However, they also showed that small muscle samples, and more importantly single fibers, existed as a continuum from one phenotype to another. Most fibers possessed mixtures of mRNA for MHC isoforms that were unexpected based on protein analysis. These findings illustrate that muscle fibers in general may possess a phenotype that is intermediate between the extremes of `pure' fiber types, not only at the MHC level but also in terms of whole myofibrillar assemblages. This study supports and extends our recent observations of mixed phenotype fibers in lobster claw and leg muscles. The existence of single fiber polymorphism in an invertebrate species underscores the generality of the phenomenon in skeletal muscles and emphasizes the need for an understanding of the proximal causes and physiological consequences of these intermediate fiber types.
Temperature acclimation modifies Na+ current in fish cardiac myocytes
Authors: Haverinen Jaakko , Vornanen Matti 
Published: July 2004

SUMMARYThe present study was designed to test the hypothesis that temperature acclimation modifies sarcolemmal Na+ current (INa) of the fish cardiac myocytes differently depending on the animal's lifestyle in the cold. Two eurythermal fish species with different physiological strategies for surviving in the cold, a cold-dormant crucian carp (Carassius carassius L.) and a cold-active rainbow trout (Oncorhynchus mykiss), were used in acclimation experiments. The INa of carp and trout were also compared with INa of a cold stenothermal burbot(Lota lota). In accordance with the hypothesis, cold-acclimation decreased the density of INa in crucian carp and increased it in rainbow trout, suggesting depression of impulse conduction in cold-acclimated carp and positive compensation of impulse propagation in cold-acclimated trout. The steady-state activation curve of trout INa was shifted by 6 mV to more negative voltages by cold acclimation, which probably lowers the stimulus threshold for action potentials and further improves cardiac excitability in the cold. In burbot myocytes, the INa density was high and the position of the steady-state activation curve on the voltage axis was even more negative than in trout or carp myocytes, suggesting that the burbot INa is adapted to maintain high excitability and conductivity in the cold. The INa of the burbot heart differed from those of carp and trout in causing four times larger charge influx per excitation, which suggests that INa may also have a significant role in cardiac excitation–contraction coupling of the burbot heart. In summary, INa of fish cardiac myocytes shows thermal plasticity that is different in several respects in cold-dormant and cold-active species and thus has a physiologically meaningful role in supporting the variable life styles and habitat conditions of each species.