bluuebunny/crossref_metadata_2025 huggingface dataset:
Commingled and Air Jet-textured Hybrid Yarns for Thermoplastic Composites
Authors: Alagirusamy Ramasamy , Ogale Vinayak
Published: July 2004

Hybrid yarns have reinforcing and matrix-forming filaments combined together in order to reduce the problems associated with high melt viscosity of thermoplastic matrices. Among hybrid yarns, commingled and air-textured yarns, which are produced with air jets have demonstrated high flexibility and good mixing of constituent filaments. Many research findings have been reported on the structure and properties of intermingled and air-textured yarns having low-modulus apparel-grade filaments. The relationships between air jet, filament yarn, and the processing parameters are critically reviewed. It is emphasized that there is an immediate need to study the mixing behavior of combination of high- and low-modulus filaments in air jet, which has not been investigated in detail in the published literature, in order to improve the mixing of these filaments. The methods used to characterize hybrid yarns are discussed. The need to study and improve the stability of the hybrid yarns in terms of maintaining the level of mixing of constituent filaments across the cross section is also established.
Waterproof Breathable Polymeric Coatings Based on Polyurethanes
Authors: Jassal Manjeet , Khungar Amit , Bajaj Pushpa , Sinha T. J. M.
Published: July 2004

The performance of environmentally friendly water-based polyurethane dispersions (PUD) for waterproof breathable coating was studied. The effect of the nature of PUD, number of coatings, incorporation of additives, and processing conditions on the breathable properties of cotton fabric was evaluated. The relative proportions of hydrophilic and hydrophobic components had a direct influence on the breathable properties of the coated cotton samples. The increase in hydrophilic component resulted in an increased water vapor penetration and lower water resistance to water penetration in the coated samples. For all the compositions, the durability of the coatings was found to improve with the incorporation of polymeric binder in the coating formulation. The air permeability values of the coated samples were found to be orders of magnitude lower than the control (uncoated) fabric sample.
Passing, Cultural Performance, and Individual Agency: Performative Reflections on Black Masculine Identity
Authors: Alexander Bryant Keith
Published: July 2004

This performative article uses the trope of “passing” as reference to crossing racial identity borders as well as to intra/interracial issues of identity and authenticity. Passing is constructed as a performative accomplishment and assessment by both the group claimed and the group denied. This article is structured around three divisions—passing as cultural performance, the social construction of identity, and the quest for self-definition of socially mediated expectations. All issues are centered within the specific concerns of Black masculine identity. In the process, the essay also seeks to establish the notion of an integrative ethnography of performance that envelops the critique of a performance as a part of the overall textual presentation of experience.
Media Propaganda and Spectacle in the War on Iraq: a Critique of U.S. Broadcasting Networks
Authors: Kellner Douglas
Published: July 2004

The author shows how, during the 2003 Iraq war, the U.S. broadcasting network provided a conduit for Bush administration and Pentagon propaganda. Whereas the explicit war aims were to shut down Iraq’s “weapons of mass destruction” and thus enforce UN resolutions that mandated that Iraq eliminate its offensive weapons, there were many hidden agendas in the Bush administration offensive against Iraq, such as the promotion of a new doctrine of preemptive strikes, control of Iraqi oil, and producing a major media spectacle that would help Bush win the 2004 presidential election. In this study, the author analyzes the forms of media propaganda promoted by the Bush administration. He argues that the U.S. broadcasting networks helped Bush advance his agenda, but that the media spectacle of a U.S. military triumph is turning into a negative spectacle of a morass that undermines the Bush administration rationale for the invasion.
Evaluation of different methods of leukoreduction of donor platelets to prevent alloimmune platelet refractoriness and induce tolerance in a canine transfusion model
Authors: Slichter Sherrill J. , Fish Douglas , Abrams V. Kraig , Gaur Lakshmi , Nelson Karen , Bolgiano Doug
Published: July 2004

The effectiveness of different methods of leukoreduction in preventing alloimmune platelet refractoriness was evaluated in a canine model. Platelets from a random donor dog were administered for up to 8 weeks or until platelet refractoriness. Standard (STD; unmodified) platelets were accepted by 14% of recipients (n = 7) compared with 14% for centrifuge leukoreduced (C-LR) platelets (n = 21) and 31% for filter leukoreduced (F-LR) platelets (n = 13; no significant differences). Surprisingly, using both F-LR and C-LR platelets was highly effective (87% acceptance, n = 15). Transfusing F-LR/C-LR red blood cells (n = 4) or F-LR/C-LR plasma (n = 4), along with F-LR/C-LR platelets, did not affect platelet acceptance (100% acceptance). Overall acceptance of F-LR/C-LR platelets was 91% (n = 23; P ≤ .05 versus STD, C-LR, or F-LR platelets). F-LR/C-LR transfusions also induced tolerance to subsequent STD platelet transfusions from the same donor (82% acceptance, n = 19) as well as to donor skin grafts without recipient immunosuppression (57% acceptance, n = 7). To evaluate mechanisms of tolerance induction, F-LR/C-LR platelets were γ-irradiated. Although the γ-irradiated F-LR/C-LR platelets were uniformly accepted (n = 6), tolerance to STD platelets was lost. These data suggest that some allostimulatory white cells are filter adherent, whereas others escape filtration but can be removed by centrifugation and tolerance requires a residual functioning white cell.
Glutathione-S-transferase π inhibits As2O3-induced apoptosis in lymphoma cells: involvement of hydrogen peroxide catabolism
Authors: Zhou Li , Jing Yongkui , Styblo Miroslav , Chen Zhu , Waxman Samuel
Published: July 2004

Arsenic trioxide (As2O3) is an effective agent for the treatment of relapsed and refractory acute promyelocytic leukemia by induction of partial differentiation and apoptosis. As2O3, at therapeutic concentrations (1-2 μM), induced apoptosis in Raji lymphoma cells but not in Jurkat lymphoma cells, which inversely correlated with the levels of glutathione-S-transferase π (GSTP1), but not GSTπ1 and GSTM1, expression and activity. GSTP1 mRNA, protein level, and activity were high in Jurkat cells but undetectable in Raji cells. Stable transfection of GSTP1 into Raji cells decreased the amount of As2O3-induced apoptosis. Apoptosis induced by therapeutic concentrations of As2O3 in Raji cells is related to increasing H2O2 intracellular accumulation but not to JNK activation. Forced expression of GSTP1 by transfection of Raji cells significantly decreased the basal amount of H2O2 and its levels after therapeutic concentration of As2O3 treatment. Added exogenous H2O2 was removed more rapidly, which correlated with a greater decrease in reduced glutathione level in Raji clones expressing GSTP1 than in those clones without GSTP1 expression. Overexpression of GSTP1 in transfected Raji clones was also found to decrease the retention of As2O3. These data suggest that GSTP1 blocks As2O3-induced apoptosis in lymphoma cells by decreasing intracellular amounts of H2O2 by catabolism and H2O2 production by decreasing the intracellular retention of As2O3.
Human CD62L– memory T cells are less responsive to alloantigen stimulation than CD62L+ naive T cells: potential for adoptive immunotherapy and allodepletion
Authors: Foster Aaron E. , Marangolo Marina , Sartor Mary M. , Alexander Stephen I. , Hu Min , Bradstock Kenneth F. , Gottlieb David J.
Published: July 2004

Selective depletion of alloreactive T cells from allogeneic stem cell grafts can reduce graft-versus-host disease (GVHD) while preserving beneficial effects of T cells including facilitation of engraftment, protection against opportunistic infection, and reduced relapse risk. Memory T cells (CD62L–) represent a population of T cells that have previously encountered pathogens and may contain fewer T cells capable of recognizing neoantigens including recipient allogeneic antigen (aAg). We investigated whether human naive (CD62L+) or memory (CD62L–) T cells had different capacities to respond to aAg by assessing their ability to proliferate in response to and lyse HLA-mismatched Epstein-Barr virus–transformed B cells. Freshly sorted and in vitro expanded CD62L– memory T cells were less responsive to aAg stimulation than were CD62L+ naive T cells but contained higher levels of cytomegalovirus (CMV)–specific T cells. Analysis of T cell receptor (TCR) repertoire showed restricted TCR diversity in the memory T-cell population possibly due to selection associated with chronic exposure to common pathogens. Memory T cells may represent a donor cell subpopulation suitable for enhancing immune reconstitution without increasing the risk of GVHD.
Constitutively active Notch4 promotes early human hematopoietic progenitor cell maintenance while inhibiting differentiation and causes lymphoid abnormalities in vivo
Authors: Vercauteren Suzanne M. , Sutherland Heather J.
Published: July 2004

Notch transmembrane receptors are known to play a critical role in cell-fate decisions, with Notch1 shown to enhance self-renewal of hematopoietic stem cells and cause T-cell leukemia. Four Notch receptors exist, and the extent of redundancy and overlap in their function is unknown. Notch4 is structurally distinct from Notch1 through Notch3 and has not been extensively studied in hematopoiesis. By polymerase chain reaction (PCR) we find Notch4 transcript expression in human marrow cells and in both CD34+ and CD34– populations. When constitutively active Notch1 or Notch4 was overexpressed in normal human marrow or cord cells, we found reduced colony-forming and short-term proliferative ability while the primitive progenitor content of myeloid long-term cultures was significantly increased. Notch4–intracellular domain (Notch4-IC)–transduced cord cells transplanted into β2-microglobulin–/– nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice resulted in significantly higher levels of engraftment of both green fluorescent protein–positive (GFP+) and GFP– populations as compared with controls. GFP+ cells in bone marrow and spleen of animals that had received transplants gave rise to an immature CD4+CD8+ T-cell population, whereas B-cell development was blocked. These results indicate that activation of Notch4 results in enhanced stem cell activity, reduced differentiation, and altered lymphoid development, suggesting it may influence both stem cells and the fate of the common lymphoid progenitor.
Formation of human hepatocytes by human hematopoietic stem cells in sheep
Authors: Almeida-Porada Graça , Porada Christopher D. , Chamberlain Jason , Torabi Ali , Zanjani Esmail D.
Published: July 2004

We took advantage of the proliferative and permissive environment of the developing preimmune fetus to develop a noninjury large animal model in sheep, in which the transplantation of defined populations of human hematopoietic stem cells resulted in the establishment of human hematopoiesis and led to the formation of significant numbers of long-lasting, functional human liver cells, with some animals exhibiting levels as high as 20% of donor (human) hepatocytes 11 months after transplantation. A direct correlation was found between hepatocyte activity and phenotype of transplanted cells, cell dose administered, source of cells used on a cell-per-cell basis (bone marrow, cord blood, mobilized peripheral blood), and time after transplantation. Human hepatocytes generated in this model retained functional properties of normal hepatocytes, constituted hepatic functional units with the presence of human endothelial and biliary duct cells, and secreted human albumin that was detected in circulation. Transplanting populations of hematopoietic stem cells can efficiently generate significant numbers of functional hepatic cells in this noninjury large animal model and thus could be a means of ameliorating or curing genetic diseases in which a deficiency of liver cells or their products threatens the life of the fetus or newborn.
Segregation of lipid raft markers including CD133 in polarized human hematopoietic stem and progenitor cells
Authors: Giebel Bernd , Corbeil Denis , Beckmann Julia , Höhn Johannes , Freund Daniel , Giesen Kay , Fischer Johannes , Kögler Gesine , Wernet Peter
Published: July 2004

During ontogenesis and the entire adult life hematopoietic stem and progenitor cells have the capability to migrate. In comparison to the process of peripheral leukocyte migration in inflammatory responses, the molecular and cellular mechanisms governing the migration of these cells remain poorly understood. A common feature of migrating cells is that they need to become polarized before they migrate. Here we have investigated the issue of cell polarity of hematopoietic stem/progenitor cells in detail. We found that human CD34+ hematopoietic cells (1) acquire a polarized cell shape upon cultivation, with the formation of a leading edge at the front pole and a uropod at the rear pole; (2) exhibit an amoeboid movement, which is similar to the one described for migrating peripheral leukocytes; and (3) redistribute several lipid raft markers including cholesterol-binding protein prominin-1 (CD133) in specialized plasma membrane domains. Furthermore, polarization of CD34+ cells is stimulated by early acting cytokines and requires the activity of phosphoinositol-3-kinase as previously reported for peripheral leukocyte polarization. Together, our data reveal a strong correlation between polarization and migration of peripheral leukocytes and hematopoietic stem/progenitor cells and suggest that they are governed by similar mechanisms.
Mechanisms regulating the recruitment of macrophages into hypoxic areas of tumors and other ischemic tissues
Authors: Murdoch Craig , Giannoudis Athina , Lewis Claire E.
Published: July 2004

The mechanisms responsible for recruiting monocytes from the bloodstream into solid tumors are now well characterized. However, recent evidence has shown that these cells then differentiate into macrophages and accumulate in large numbers in avascular and necrotic areas where they are exposed to hypoxia. This parallels their tendency to congregate in ischemic areas of other diseased tissues such as atherosclerotic plaques and arthritic joints. In tumors, macrophages appear to undergo marked phenotypic changes when exposed to hypoxia and to switch on their expression of a number of mitogenic and proangiogenic cytokines and enzymes. This then promotes tumor growth, angiogenesis, and metastasis. Here, we compare the various mechanisms responsible for monocyte recruitment into tumors with those regulating the accumulation of macrophages in hypoxic/necrotic areas. Because the latter are best characterized in human tumors, we focus mainly on these but also discuss their relevance to macrophage migration in ischemic areas of other diseased tissues. Finally, we discuss the relevance of these mechanisms to the development of novel cancer therapies, both in providing targets to reduce the proangiogenic contribution made by hypoxic macrophages in tumors and in developing the use of macrophages to deliver therapeutic gene constructs to hypoxic areas of diseased tissues.
Modulation of hematopoietic and endothelial cell differentiation from mouse embryonic stem cells by different culture conditions
Authors: Zhang Wen Jie , Park Changwon , Arentson Elizabeth , Choi Kyunghee
Published: July 2004

Embryonic stem (ES) cells can differentiate into many different somatic cells in culture. To better correlate hematopoietic and endothelial cell differentiation of ES cells in currently available protocols, we compared fetal liver kinase-1 (Flk-1)–, stem cell leukemia (Scl)–, and vascular endothelial–cadherin (VE-cadherin)–expressing cells generated in embryoid bodies (EBs) and on OP9 cells. We report that the kinetics of Scl and Flk-1 expression were similar in EBs and OP9 cells, although Flk-1 expression was extended on OP9 cells. CD45+ and Ter-119+ cells developed more efficiently in EBs, whereas VE-cadherin+ cells developed largely on OP9 cells. Cell sorting and replating studies showed that Scl+ cells, not Flk-1+ or VE-cadherin+ cells, were enriched for primitive and definitive hematopoietic progenitors. Our studies indicate that optimal hematopoietic and endothelial cell differentiation occur in EBs and on OP9 cells, respectively. Regardless of the culture systems used, Scl is the most relevant marker for enriching primitive and definitive hematopoietic progenitors.
Control of Phosphatase and Tensin Homolog (PTEN) Gene Expression in Normal and Neoplastic Thyroid Cells
Authors: Tell Gianluca , Pines Alex , Arturi Franco , Cesaratto Laura , Adamson Eileen , Puppin Cinzia , Presta Ivan , Russo Diego , Filetti Sebastiano , Damante Giuseppe
Published: July 2004

The lipid phosphatase, phosphatase and tensin homolog (PTEN), is a key element in controlling cell growth and survival and has a well established role as tumor suppressor protein in many neoplasia. Several data indicate that silencing of PTEN gene expression may be relevant in follicular thyroid cell transformation. Thus, in the present study regulation of PTEN gene expression in thyroid cells was investigated. Cotransfection experiments indicated that in normal FRTL-5 rat thyroid cells, PTEN promoter activity was increased by overexpression of the transcription factor early growth response protein-1 (Egr-1). Moreover, Western blot experiments indicated that when Egr-1 expression was up-regulated by treating FRTL-5 cells with H2O2, an increase in PTEN expression was also observed. TSH induced opposite modifications on PTEN and Egr-1 protein levels. Moreover, acute or chronic TSH stimulation determined distinct effects. In fact, acute TSH stimulation (30 and 60 min) induced a decrease in PTEN, but an increase in Egr-1 protein levels. These effects were cAMP dependent; in fact, they were mimicked by forskolin. A chronic TSH treatment (5 d) stimulated PTEN protein expression, whereas Egr-1 protein was down-regulated. In contrast to normal thyroid cells, when the thyroid tumor cell lines ARO and BCPAP were exposed to H2O2, neither Egr-1 nor PTEN protein levels were increased. Acute stimulation of ARO and BCPAP cells with forskolin increased Egr-1, but not PTEN, protein levels. Therefore, thyroid tumor cell lines show alteration of PTEN gene expression regulation. RT-PCR experiments performed on human thyroid tumors showed that the absence of Egr-1 mRNA is always paralleled by the absence of PTEN mRNA. Thus, modification of the Egr-1-dependent mechanisms may play a role in the silencing of PTEN gene expression occurring during thyroid cell transformation.
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

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

The 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

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

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

The 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.
The winged helix transcription factor Foxg1 facilitates retinal ganglion cell axon crossing of the ventral midline in the mouse
Authors: Pratt Thomas , Tian Natasha M. M.-L. , Simpson T. Ian , Mason John O. , Price David J.
Published: July 2004

During normal development, retinal ganglion cells (RGCs) project axons along the optic nerve to the optic chiasm on the ventral surface of the hypothalamus. In rodents, most RGC growth cones then cross the ventral midline to join the contralateral optic tract; those that do not cross join the ipsilateral optic tract. Contralaterally projecting RGCs are distributed across the retina whereas ipsilaterally projecting RGCs are concentrated in temporal retina. The transcription factor Foxg1 (also known as BF1) is expressed at several key locations along this pathway. Analysis of Foxg1 expression using lacZ reporter transgenes shows that Foxg1 is normally expressed in most, if not all, nasal RGCs but not in most temporal RGCs, neither at the time they project nor earlier in their lineage. Foxg1 is also expressed at the optic chiasm. Mice that lack Foxg1 die at birth and, although the shape of their eyes is abnormal, their retinas still project axons to the brain via the optic chiasm. Using anterograde and retrograde tract tracing, we show that there is an eightfold increase in the ipsilateral projection in Foxg1-/- embryos. The distributions of cells expressing the transcription factors Foxg1 and Nkx2.2,and cell-surface molecules Ephb2, ephrin B2 and SSEA-1 (Fut4) have been correlated to the normally developing retinothalamic projection and we show they are not much altered in the developing Foxg1-/-retina and optic chiasm. As much of the increased ipsilateral projection in Foxg1-/- embryos arises from temporal RGCs that are unlikely to have an autonomous requirement for Foxg1, we propose that the phenotype reflects at least in part a requirement for Foxg1 outwith the RGCs themselves, most likely at the optic chiasm.
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

This 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

Fluid 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

We 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

The 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

We 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

Fringillids 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

In 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

The 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.
A crustacean nitric oxide synthase expressed in nerve ganglia, Y-organ,gill and gonad of the tropical land crab,Gecarcinus lateralis
Authors: Kim Hyun-Woo , Batista Luisa A. , Hoppes Jodi L. , Lee Kara J. , Mykles Donald L.
Published: July 2004

NO signaling is involved in many physiological processes in invertebrates. In crustaceans, it plays a role in the regulation of the nervous system and muscle contraction. Nested reverse transcription-polymerase chain reaction(RT-PCR) and 5′ and 3′ rapid amplification of cDNA ends (RACE) PCR generated a full-length cDNA sequence (3982 bp) of land crab NO synthase(Gl-NOS) from molting gland (Y-organ) and thoracic ganglion mRNA. The open reading frame encoded a protein of 1199 amino acids with an estimated mass of 135 624 Da. Gl-NOS had the highest sequence identity with insect NOS. The amino acid sequences for binding heme and tetrahydrobiopterin in the oxygenase domain, binding calmodulin and binding FMN, FAD and NADPH in the reductase domain were highly conserved. Gl-NOS had single amino acid differences in all three highly conserved FAD-binding sequences, which distinguished it from other NOS sequences. RT-PCR showed that the Gl-NOS mRNA was present in testis,ovary, gill, eyestalk neural ganglia, thoracic ganglion and Y-organ. NOS mRNA varied between preparations of Y-organ, thoracic ganglion and gill, while NOS mRNA was at consistently high levels in the ovary, testis and eyestalk ganglia. Immunohistochemistry confirmed that the Gl-NOS protein was expressed in Y-organ, ovary and gill. These results suggest that NOS has functions in addition to neuromodulation in adults, such as regulating or modulating ecdysteroid synthesis in the Y-organ.
Cardiac morphodynamic remodelling in the growing eel (Anguilla anguilla L.)
Authors: Cerra M. C. , Imbrogno S. , Amelio D. , Garofalo F. , Colvee E. , Tota B. , Icardo J. M.
Published: July 2004

The morphodynamic changes occurring during growth were evaluated in the eel(Anguilla anguilla L.) heart. Using an in vitro working heart preparation, cardiac performance of small (body mass 96.76±27.49 g; mean ± s.d.) and large (body mass 656±12 g; mean± s.d.) eels was compared under basal conditions and under loading (i.e. preload and afterload) challenges. A parallel morphometric evaluation of the ventricle was made using light and transmission electron microscope images.

The small eel hearts show a basal cardiac output lower than their large counterparts (heart rate fh, 38.93±2.82 and 52.7±1.8 beats min–1, respectively; stroke volume Vs, 0.27±0.017 and 0.37±0.016 ml kg–1, respectively; means ± s.e.m.). The two groups show similar responses at increasing preload, but differ remarkably at increasing afterload. Small eel hearts decreased Vs at afterload greater than 3 kPa, in contrast to larger hearts, which maintained constant Vs up to 6 kPa. These changes in mechanical performance are related to structural differences.

Compared with the small eels, the large eels show an increase in the compacta thickness and in the diameter of the trabeculae in the spongiosa,together with reduction of the lacunary spaces. The increased compacta thickness is attained by enlargements of both the muscular and vascular compartments and reduction of the interstitium; consequently, this layer appears more compacted. Both compacta and spongiosa show higher number of myocytes together with reduced cross-sectional area and myofibrillar compartment. The compacta also shows an increased mitochondrial compartment. Our results document a cardiac morphodynamic remodelling in the growing eel.