bluuebunny/crossref_metadata_2025 huggingface dataset:
No evidence for recognition errors inAcrocephaluswarblers
Authors: Røskaft Eivin , Moksnes Arne , Meilvang Dorte , Bicík Vítezslav , Jemelíková Jarmila , Honza Marcel
Published: March 2003

Failure to recognise own eggs (recognition errors) may be an important selective force behind acceptance of parasitic eggs, leading to a balance between rejecters and acceptors in a host population (the equilibrium hypothesis). We predicted that recognition errors should occur frequently among host species with intermediate rejection rates, whose rejection behaviour shows many conditional responses. The reed warblerAcrocephalus scirpaceusand great reed warblerA. arundinaceusfulfil these requirements. These two species were therefore used in an experiment where host birds were exposed to a common cuckooCuculuscanorusdummy, either <2 m or 5–10 m from the nest, at fishponds in southern Moravia (Czech Republic). The hosts responded to the cuckoo dummy, great reed warblers being much more aggressive than reed warblers, and both species being more aggressive towards the dummy when it was close to the nest than when it was farther away. We furthermore predicted that there should be more eggs rejected (ejected or nest abandoned) due to recognition errors among hosts exposed to a dummy close to the nest than among both those exposed to a dummy farther away from the nest and towards controls not exposed to cuckoo dummies. When comparing egg loss between groups of birds that were exposed to a cuckoo dummy with those that were not, we found no significant difference. However, partial egg loss was frequent among hosts in the studied population, most probably due to cuckoo depredation. We discuss why there were no detectable recognition errors in the studied population, when other researchers have claimed to have found such errors in host populations elsewhere.
Diet preferences of warblers for specific fatty acids in relation to nutritional requirements and digestive capabilities
Authors: McWilliams Scott R. , Kearney Shannon B. , Karasov William H.
Published: March 2003

During energy‐demanding periods of the annual cycle such as migration or during cold days in winter, birds store fat comprised mostly of 16‐ or 18‐carbon unsaturated fatty acids. In such situations, birds may feed selectively on foods with specific fatty acids that enable efficient fat deposition. We offered wild‐caught yellow‐rumped warblers Dendroica coronata paired choices between semi‐synthetic diets that differed only in their fatty acid composition. Warblers strongly preferred diets containing long‐chain (18:1; carbon atoms:double bonds) unsaturated, unesterified fatty acids to diets containing long‐chain saturated, unesterified fatty acids (18:0) and they preferred diets containing mono‐unsaturated fats (18:1) to diets containing poly‐unsaturated fats (18:2). The preference for diets containing long‐chain unsaturated fatty acids to diets containing long‐chain saturated fatty acids was consistent in birds tested one week after capture at 21°C, one month after capture when cold‐acclimated (1°C), and six weeks after capture at 21°C. Birds acclimated to a diet with 50% of the fat comprised of unesterified stearic acid (18:0) lost mass and reduced their food intake when we reduced ambient temperature from 21°C to 11°C over three days. We conclude that especially in energy‐demanding situations there are limits to the yellow‐rumped warblers’ ability to assimilate some long‐chain saturated fatty acids and that this digestive constraint can explain in part why yellow‐rumped warblers prefer diets containing long‐chain unsaturated fatty acids to diets containing long‐chain saturated fatty acids.
Immunological tolerance – the liver effect
Authors: Calne R. Y.
Published: March 2003

Summary: The developing immune system in the embryo is programmed to accept all its own tissues as self‐products and not react against them. It has been the aim of transplantation research for the past 40 years to try and manipulate the developed immune system temporarily to a similar status to that in the embryo at the time of an organ graft, so that the organ graft is accepted but immunity generally is not interfered with. Such a state is known as immunological tolerance and can be produced in the laboratory by a number of special techniques, none of which is appropriate for clinical use in organ grafting. In pigs and rats, an allografted liver can sometimes survive permanently without any immunosuppressive treatment in immunologically mature animals.
Different morphotypes of the tabby (EDA) dentition in the mouse mandible result from a defect in the mesio‐distal segmentation of dental epithelium
Authors: Peterková R , Kristenová P , Lesot H , Lisi S , Vonesch J‐L , Gendrault J‐L , Peterka M
Published: March 2003

Structured Abstract

Authors –
Peterková R., Kristenová P., Lesot H., Lisi S., Vonesch J‐L., Gendrault J‐L., Peterka M.

Objectives –
Prenatal identification of the different dentition morphotypes, which exist in the lower molar region of tabby (Ta) adult mice, and investigation of their origin. The mouse Ta syndrome and its counterpart anhidrotic (hypohidrotic) ectodermal dysplasia (EDA) in human are characterized by absence or hypoplasia of sweat glands, hair and teeth.

Design –
Analysis of tooth morphogenesis using serial histological sections and 3D computer aided reconstructions of the dental epithelium in the cheek region of the mandible.

Setting and Sample Population –
Institute of Experimental Medicine, Academy of Sciences, Prague. Heads of 75 Ta homozygous and hemizygous mice and 40 wild type (WT) control mice aged from embryonic day (ED) 14.0–20.5 (newborns), harvested during 1995–2001.

Outcome Measure –
Prenatal identification of five distinct morphotypes of Ta dentition on the basis of differences in tooth number, size, shape, position and developmental stage and of the morphology of the enamel knot in the most mesial tooth primordium.

Results –
The mesio‐distal length of the dental epithelium was similar in the lower cheek region in Ta and WT mice. In Ta embryos, there was altered the mesio‐distal segmentation of the dental epithelium giving rise to the individual tooth primordia. Prenatally, two basic morphotypes I and II and their particular subtypes (Ia, Ib, Ic, and IIa, IIb, respectively) of the developing dentition were identified from day 15.5. The incidence of the distinct morphotypes in the present sample did not differ from postnatal data. The proportion of the morphotype I and II was dependent on mother genotype.

Conclusion –
The different dentition morphotypes in Ta mice originate from a defect in the mesio‐distal segmentation of the dental epithelium in mouse embryos. This defect presumably leads to variable positions of tooth boundaries that do not correspond to those of the WT molars. One tooth primordium of Ta mice might be derived from adjacent parts of two molar primordia in WT mice.
Melatonin suppresses lysophosphatidylcholine enhancement of serotonin‐induced vasoconstriction in the human umbilical artery
Authors: Okatani Yuji , Wakatsuki Akihiko , Watanabe Kazushi , Taniguchi Katsunori , Fukaya Takao
Published: March 2003

We evaluated the antioxidant property of melatonin as related to the vasospastic effect of lysophosphatidylcholine (LPC), a component of oxidized lipoprotein, on the human umbilical artery. Helical sections of umbilical arteries with intact endothelium were obtained at elective cesarean delivery between 37 and 39 weeks of gestation. Changes in 5‐hydroxytryptamine (5‐HT)‐induced vasoconstriction were measured. Arterial sections were treated with LPC alone (15 or 30 μM) or pretreated with an hydroxyl radical (zrad;OH) scavenger (mannitol), a cyclooxygenase inhibitor (indomethacin, 20 μM), nitric oxide (NO) synthesis inhibitor (L‐NG‐monomethylarginine, LNMA, 2×10−4 M), or melatonin (1 or 10 μM). LPC potentiated 5‐HT‐induced contraction in a concentration‐dependent manner. Pretreatment with mannitol significantly suppressed the vasospastic effect of LPC. LNMA augmented the vasospastic effect of LPC, but indomethacin did not. Melatonin significantly suppressed the vasospastic effect of LPC in a concentration‐dependent manner. Considering a previous finding that zrad;OH and oxidized low‐density lipoprotein decrease NO production in the human umbilical artery, the vasospastic effect of LPC appear to involve suppression of endothelial NO synthesis. Melatonin significantly suppresses the vasospastic effect of LPC, probably by scavenging zrad;OH arising from LPC.
The supportive role of complement in HIV pathogenesis
Authors: Stoiber H. , Kacani L. , Speth C. , Würzner R. , Dierich M. P.
Published: March 2003

This review focuses on interactions of HIV with the first‐line defence of native immunity, the complement system. In all body compartments tested so far, HIV meets complement. Activation of the complement system results in deposition of C3 fragments on the viral surface, but in contrast to other pathogens, most of HIV is not or is only poorly lysed by membrane attack complexes. To survive complement‐mediated lysis, HIV has not only developed resistance mechanisms, but uses opsonisation with complement fragments for its own advantage. Opsonised virions interact with complement receptor‐expressing cells, which are either subsequently infected with high efficiency or retain viral particles on their surface, which promotes transmission of virus to other permissive cells. Our knowledge of these mechanisms has increased enormously over the past few years. A complete understanding of these complex interactions of HIV with the complement system opens new perspectives for development of alternative therapeutic strategies.

We like to thank Anke Stoiber for secretarial support. This work was supported in part by grants from the FWF (P14070‐MED; P13182‐MOB), the OENB (Jubiläumsfonds Nr. 8504), the 5th Frame Work of the EU (QLK 2‐1999‐01215), the State of Tyrol and Federal Ministeries.
Specificity and function of activating Ly‐49 receptors
Authors: Kane Kevin P. , Silver Elizabeth T. , Hazes Bart
Published: March 2003

Summary: Inhibitory Ly‐49 receptors allow murine natural killer (NK) cells to kill cells with aberrant class I MHC expression while sparing normal cells. This is accomplished by their recognition of specific class I MHC products and prevention of NK‐cell lysis of cells that present a normal repertoire of class I MHC ligands –“the missing self hypothesis”. However, Ly‐49 receptors that lack the cytoplasmic immunoreceptor tyrosine‐based inhibitory motif, which is required for inhibition of killing, have also been described. These receptors were found to stimulate NK killing and are therefore referred to as activating Ly‐49 receptors. Interestingly, the activating receptors have class I MHC‐binding domains that are nearly indistinguishable from those of the inhibiting receptors, and binding to class I MHC has now been demonstrated for three activating receptors. Presently, there is no defined physiological role for activating Ly‐49 receptors. Here we present an overview of current knowledge regarding the diversity, structure and function of activating Ly‐49 receptors with a focus on class I MHC specificity, and we discuss their potential role(s) in natural resistance.

This research was supported by an operating grant from the National Cancer Institute of Canada and the Canadian Cancer Society (K. P. Kane) and a Canadian Institutes for Health Research operating grant (B. Hazes). E. Silver is supported by an Alberta Heritage Foundation for Medical Research (AHFMR) studentship and K. P. Kane is an (AHFMR) senior scholar.
Regulatory T cells: the physiology of autoreactivity in dominant tolerance and “quality control” of immune responses
Authors: Coutinho Antonio , Hori Shohei , Carvalho Thiago , Caramalho Iris , Demengeot Jocelyne
Published: March 2003

Summary: Little progress has been achieved over the last 20 years on the clinical management of several conditions that relate to self‐tolerance and to the regulation of immune responses: autoimmune diseases, transplantation tolerance, tumor immunity, allergy and vaccine development in chronic infections. These failures, it is argued, are due to the inability of the prevalent “recessive tolerance” concepts to accommodate physiological autoreactivity and the regulatory potential it embodies. In this review, the advantages of “dominant tolerance” models are underlined in the light of critical evidence and in the general context of the natural autoimmune activities. The role of regulatory T cells is discussed, notably in the regulation of inflammatory reactions and, more generally, in the “quality control” of immune responses. It is anticipated that progress will be brought about by dominant tolerance approaches, and through an increased knowledge of the differentiative pathways, repertoires, mechanisms of activation and effector functions of autoreactive, regulatory T cells.
Baboons as an animal model for human immunodeficiency virus pathogenesis and vaccine development
Authors: Locher Christopher P. , Witt Stephanie A. , Herndier Brian G. , Tenner‐Racz Klara , Racz Paul , Levy Jay A.
Published: March 2003

Summary: Baboons (Papio cynocephalus) provide a valuable animal model for the study of human immunodeficiency virus (HIV) pathogenesis because HIV‐2 infection of baboons causes a chronic viral disease that progresses over several years before clinical signs of acquired immunodeficiency syndrome (AIDS) appear. Since HIV‐2‐infected baboons develop a chronic viral infection, insights into the immuno‐biology of viral latency, clinical stages of disease, virus infection of lymphatic tissue and HIV transmission can be gained using this animal model. The development of an AIDS‐like disease in baboons is viral isolate and baboon subspecies dependent. Thus, viral virulence factors and host resistance can be studied as well as the mechanisms of innate and acquired immunity. The control of virus infection is dependent upon cytotoxic and non‐cytotoxic antiviral activity of CD8+ T cells. In this regard, some of the HIV‐2‐infected baboons develop potent antiviral cellular immune responses that have a similar magnitude to that found in HIV‐1‐infected long‐term survivors (or non‐progressors). In our laboratory, baboons have been used to study DNA vaccine strategies using new cationic liposome formulations and granulocyte macrophage–colony stimulating factor and B7–2 as genetic adjuvants. The results demonstrate the value of using baboons as an animal model of AIDS pathogenesis and vaccine development.
Cellular immunology in a historical perspective
Authors: Good Robert A.
Published: March 2003

Summary: Bruton's XLA and DiGeorge syndrome patients show that two basic immune systems are distinct from each other in humans − thymus‐dependent cell‐mediated immunodeficiencies vs. antibody‐based immunodeficiencies. The appendix‐sacculus lymphoid organ of rabbits, like the bursa of Fabricius, represents a central lymphoid organ. Chronic granulomatous disease of childhood (CGD) revealed that phagocytosis killing of catalase‐positive microorganisms employ oxidative burst. Bone marrow transplantation (BMT) proved life saving in severe combined immunodeficiency (SCID). The first BMT cured XSCID and the second BMT cured a complicating aplastic anemia launching BMT as a treatment of many diseases. Now 75 fatal diseases have been cured by myeloablative BMT. BMT also cured experimental autoimmune diseases. BMT alone did not cure lupus with polyarthritis in MRL/lpr mice or polyarthritis in NZB/KN mice, but BMT plus bone (stromal cell) transplants cured these diseases. Autoimmune diseases and lethal glomerulonephritis were prevented or cured in BXSB mice by mixed allogeneic plus syngeneic BMT. X‐linked Hyper IgM syndrome (XHIM) was also cured by BMT from a 2‐year‐old MHC‐matched sibling donor. Nonmyeloablative BMT plus mesenchymal stem cells (stromal cells) was effective treatment for a form of collagen‐vascular disease and also a lethal form of hypophosphatasia. Mannan‐binding lectin, an opsonin that activates the complement system when mutated and at low levels in blood, opens a door to frequent infections throughout childhood and adult life. This new immunodeficiency is based on genetic mutations that involve a native defense system.
Integration of inflammatory signals by rolling neutrophils
Authors: Ley Klaus
Published: March 2003

Summary: In inflammation, neutrophils roll along the endothelial wall of postcapillary venules and sample inflammatory signals. Neutrophil activation is required to generate β2 integrin bonds with the endothelium that are strong enough to withstand the flow forces and thus achieve arrest from the rolling state. Unlike naïve T cells, neutrophils are not only activated by ligation of G‐protein coupled receptors with chemokines and other chemoattractants but also receive signals from engagement of adhesion molecules including the selectins and β2 integrins. Rolling neutrophils integrate the sum total of inputs received while scanning the inflamed endothelium. In this process, the velocity of rolling neutrophils systematically decreases as a function of their contact time with the inflamed endothelium. If an activation threshold is reached, β2 integrins switch to the high‐affinity conformation, redistribute on the cell surface, and trigger arrest and adhesion. Rolling cells that do not reach the activation threshold detach from the endothelium and are released back into the circulation. The role of chemokines, adhesion molecules, and other activating inputs involved in this response as well as signaling pathways are the subjects of ongoing investigations. This review provides a conceptual framework for neutrophil recruitment from the flowing blood.
Stability and plasticity of wild‐type and Pax5‐deficient precursor B cells
Authors: Rolink Antonius G. , Schaniel Christoph , Melchers Fritz
Published: March 2003

Summary: In Pax5‐deficient mice, B cell development is blocked at the pre‐BI cell stage. Like wild‐type, Pax5–/– pre‐BI cells can be grown long‐term in vitro in the presence of stromal cells and IL‐7. However, unlike their wild‐type in vitro‐grown counterparts, Pax5–/– pre‐BI cells possess an extraordinary developmental plasticity showing hematopoietic stem cell features such as multipotency and self renewing capacity. Here we review and discuss this in vitro and in vivo plasticity of Pax5–/– pre‐BI cells.
Interface accumulation of receptor/ligand couples in lymphocyte activation: methods, mechanisms, and significance
Authors: Wülfing Christoph , Tskvitaria‐Fuller Irina , Burroughs Nigel , Sjaastad Michael D. , Klem Jennifer , Schatzle John D.
Published: March 2003

Summary: Cellular interaction is vital to the activation of most lymphocytes. At the interface between the lymphocyte and the cell that activates it, multiple receptor/ligand pairs accumulate in distinct patterns. This accumulation is intriguing, as it is likely to shape the quality of receptor signaling and thereby lymphocyte behavior. Here we address such receptor/ligand accumulation with an emphasis on T and natural killer (NK) cells. First, we discuss the strengths and limitations of commonly used approaches to visualize receptor/ligand accumulation. Second, we discuss two principal mechanisms of receptor and ligand translocation, diffusion and cytoskeletal transport, as understanding these mechanisms can be invaluable in the determination of the significance of receptor/ligand accumulation. We show that the extent of receptor/ligand accumulation at the T cell/antigen presenting cell interface is dominated by diffusion for all but the lowest affinity interactions, while patterning of these receptors/ligands within the interface is strongly influenced by cytoskeletal transport. Third, we discuss two specific issues in lymphocyte receptor/ligand accumulation. We review the abundant but frequently controversial data on T cell receptor (TCR)/major histocompatibility complex (MHC) accumulation and suggest that central TCR/MHC accumulation is a mediator of efficient T cell activation. In the investigation of NK cell/target cell interactions, we characterize the often tentative NK cell/target cell couple maintenance, as it creates a major obstacle in studying receptor/ligand accumulation.
Bile salt independent flow during bile salt‐induced choleresis and cholestasis in the rat: role of biliary thiol secretion
Authors: Bouchard Guylaine , Tuchweber Beatriz , Yousef Ibrahim M.
Published: March 2003

Abstract: Aims/Background: Previous studies have shown that the generation of the so‐called “bile salt‐independent flow” (BSIF) may be partly dependent on the hepatic availability and rate of canalicular secretion of osmotically active substances such as glutathione (GSH) and derived thiols. This study examined the role of common bile salts (BS) on the BSIF formation under both choleretic and cholestatic conditions, and on the relationship of the BSIF to the biliary thiol secretion. Methods: Experiments were carried out in adult male Sprague‐Dawley rats both in situ in the isolated perfused rat liver and in vivo. The effect of choleretic and cholestatic doses of BS on the biliary BS secretion rate (BSSR), BS‐dependent flow (BSDF), and BSIF was evaluated. Results: In the perfused rat liver, the infusion of low and physiological doses of taurocholic acid stimulated the biliary BSSR, BSDF, and BSIF. This was associated with increased biliary thiol secretion and thiol‐dependent bile flow. In vivo administration of taurocholic acid, taurochenodeoxycholic acid or taurolithocholic acid in step‐wise increasing doses leading to cholestasis showed that the onset of cholestasis was not accompanied by a significant decline in the BSSR or BSDF but rather by a marked inhibition of the apparent BSIF. During cholestasis, the three BS produced a significant reduction of biliary thiol secretion, with a marked decrease in thiol‐dependent bile flow sufficient to account for a major proportion of BSIF inhibition. This decline in thiol secretion occurred before the drop in biliary BS secretion and was more pronounced than the reduction in BS output. No change in hepatic thiol content was observed. Administration of free or glyco‐conjugated BS also resulted in a significant decrease of BSIF during the cholestatic period, suggesting a common role for BSIF inhibition in BS‐induced cholestasis. Conclusion: The changes in bile flow during BS‐induced choleresis and cholestasis are mediated by changes in the portion of the BSIF regulated by the thiol secretion.
Absence of hepatitis C genome in semen of infected men by polymerase chain reaction, branched DNA and in situ hybridization
Authors: Debono Emmanuel , Halfon Philippe , Bourliere Marc , Gerolami‐Santandrea Victoria , Gastaldi Marguerite , Castellani Paul , Cartouzou Guy , Botta‐Fridlund Danielle , Cau Pierre , Gauthier André
Published: March 2003

Abstract: Background/Aims: The presence or absence of hepatitis C virus (HCV) RNA in the semen of infected man remains controversial, mainly due to technical difficulties associated with nucleic acid detection. The aims of this study were to assess the presence of HCV RNA in spermatozoa and in seminal fluid using different polymerase chain reaction (PCR)‐ and non‐PCR‐dependent methods and, in the case of HCV presence, to correlate this detection with the viraemia. Methods: Serum and semen from 25 chronically infected hepatitis C patients were studied. The semen was separated into spermatozoa and seminal fluid and HCV RNA was analysed in the two fractions using RT‐PCR and branched DNA. The presence of HCV RNA in pelleted cells was also assessed using in situ hybridization. Results: All three approaches failed to demonstrate HCV RNA in semen. The presence of an inhibitor of the PCR was demonstrated in seminal fluid but not in spermatoza. Conclusion: Our results confirmed the lack of detection of HCV RNA in semen by PCR‐ and non‐PCR‐dependent techniques and support the view that viral contamination in semen remains, if present, at a very low level. Nevertheless, epidemiological studies are required to definitively assess the absence of sexual transmission of HCV.
Neopterin and interleukin‐8 – prognosis in alcohol‐induced cirrhosis
Authors: Homann Christian , Benfield Thomas Lars , Graudal Niels Albert , Garred Peter
Published: March 2003

Abstract: Background: Neutrophil cytotoxity and activated macrophages have been implicated in the pathogenesis of alcohol‐induced liver disease. The aim of this study was to relate plasma levels of neopterin, a marker of activation of the cellular immune system, and IL‐8, a neutrophil chemotactic factor, with severity of liver disease and prognosis in patients with alcohol‐induced cirrhosis. Methods: Plasma concentrations of neopterin and IL‐8 were assessed in 81 patients with alcohol‐induced cirrhosis admitted to the Department of Medicine B, Bispebjerg Hospital, Copenhagen, Denmark, and in 16 healthy controls. After a median follow‐up period of 5 years, mortality and death causes were registered. The patients were divided into groups according to the major contributing cause of death: infection, upper gastrointestinal bleeding or hepatic coma. Results: Neopterin and IL‐8 levels were increased in the cirrhosis patients, but not significantly related to Child‐Pugh classification. Five‐year mortality was 67%. High neopterin levels (>upper quartile) were an independent predictor of death (p=0.01, Log rank and p<0.02, Cox). High IL‐8 levels (>upper quartile) were of no significant prognostic value for overall mortality. Causes of death related mortality were as follows (Log rank): Neopterin; p=0.009, p=0.84 and p=0.94, and IL‐8; p=0.36, p=0.002 and p=0.27, respectively, according to infection, bleeding and coma as causes of death. Conclusions: Neopterin and IL‐8 plasma levels are raised in patients with alcohol‐induced cirrhosis, and are predictive of mortality associated with infections and upper gastrointestinal bleeding, respectively.
Assessment of hepatic ischaemia reperfusion injury by measuring intracellular tissue oxygenation using near infrared spectroscopy
Authors: El‐Hamid El‐Desoky Abd , Delpy David T. , Davidson Brian R. , Seifalian Alexander M.
Published: March 2003

Abstract: Aims/Background: Hepatic ischaemia/reperfusion (I/R) injury is a major cause of liver damage during liver surgery and transplantation. The relationship between the severity of I/R injury and the degree of intracellular hypoxia has not been investigated. Methods: New Zealand white rabbits were used in 4 groups (n=6 each). At laparotomy, left lobe hepatic ischaemia was produced for 30, 45, or 60 min followed by 60 min reperfusion and compared with controls. Liver function, bile flow, and flow in the hepatic microcirculation (HM) were measured. Near infrared spectroscopy (NIRS) was used to monitor hepatic oxyhaemoglobin (HbO2), deoxyhaemoglobin (Hb), and cytochrome oxidase (Cyt Ox). Results: I/R injury produced deranged liver function tests, reduced bile flow, and reduced flow in the microcirculation in comparison with controls. During ischaemia, HbO2 and Cyt Ox were significantly reduced in comparison with controls. After reperfusion, a biphasic change in tissue oxygenation was observed, with an initial increase in HbO2 and Cyt Ox followed by a progressive reduction. The reduction in tissue oxygenation with ischaemia and reperfusion paralleled the ischaemia time. After I/R, the changes in Cyt Ox (intracellular oxygenation) significantly correlated with the parameters of hepatocellular injury to a higher degree than HbO2 (extracellular oxygenation). Conclusion: This study shows the potential of monitoring the degree of I/R injury by measuring hepatic tissue intracellular oxygenation.
Immunohistochemical and electron microscopic study of extrinsic hepatic reinnervation following orthotopic liver transplantation in rats
Authors: Takahashi Tsuyoshi , Kakita Akira , Sakamoto Izumi , Takahashi Yoshihito , Hayashi Keiko , Tadokoro Fumihiko , Yamashina Shohei
Published: March 2003

Abstract: Background/Aims: Because little has been known about the morphological and functional consequences of liver transplantation on hepatic autonomic nerves, we examined the time‐course of extrinsic hepatic innervation at the level of the porta hepatis of liver allografts. Methods: Orthotopic liver transplantation was performed using male Lewis rats. Crosscut tissue specimens were obtained postoperatively for up to 6 months from the porta hepatis of transplanted livers, and processed for immunohistochemical staining for protein gene product 9.5 (PGP 9.5) and growth‐associated protein 43 (GAP‐43), and for transmission electron microscopy (TEM). Results: Extrinsic nerve fibers at the porta hepatis stained positively for PGP 9.5 throughout the entire study period. In contrast, the immunoreactivity of GAP‐43 was negative at postoperative day (POD) 1 and 2. GAP‐43‐positive nerves were first observed to appear in the porta hepatis at POD 3. The immunoreactivity of GAP‐43 remained positive thereafter until 3 months post‐OLT, and became negative in all the specimens at 4 months post‐OLT. Transmission electron microscopy demonstrated a small number of regenerating axons existing among many degenerating axons at POD 3. At 3 months post‐OLT, most regenerating axons had been fully ensheathed by the cytoplasm of Schwann cells, although their density remained at a lower level compared with normal. Conclusion: The results of this study suggest that liver allografts become extrinsically reinnervated, with the regenerating axons reaching the hepatic hilus 3 days after transplantation. The process of extrinsic hepatic reinnervation is considered to almost terminate 4 months after transplantation in rats.
Infection of macaques with a molecular clone, SHIVSF33A2, provides evidence for tissue specific variants
Authors: Buckner C.M. , Gettie A. , Tan R.C.H. , Eshetu T. , Ratterree M. , Blanchard J. , Cheng‐Mayer C. , Harouse J.M.
Published: March 2003

Abstract: Infection of rhesus macaques with chimeric simian‐human immunodeficiency viruses (SHIV) is an established model to study acquired immunodeficiency syndrome (AIDS) pathogenesis. Such a controlled system allows for detailed analysis of the molecular determinants of viral pathogenesis in addition to studying host‐specific immune responses that modulate disease progression. Furthermore, the use of a pathogenic molecular clone affords the opportunity to study both viral evolution within a host and to examine the generation of tissue specific variants. In this report we describe viral diversification within tissues of two rhesus macaques infected intravenously with the CXCR4‐specific molecular clone SHIVSF33A2. Heteroduplex tracking analysis (HTA) was used to determine the complexity of viral DNA within distinct lymphoid tissues. Not surprising, heterogeneity of the proviral quasispecies in tissues obtained during the acute infection was limited. However, tissues obtained at necropsy harbored a more diverse and often different population of env variants. As the inoculating virus is a molecular clone, the variants generated are likely due to the presence of tissue specific selective forces rather than a founder's effect.
Neonatal behavioral scoring of common marmosets (Callithrix jacchus): relation to physical condition and survival
Authors: Tardif S.D. , Layne D.G. , Cancino L. , Smucny D.A.
Published: March 2003

A seven‐task behavioral test was performed on 86 common marmoset (Callithrix jacchus) infants, 24–36 h following birth. This report describes the test outcome and its relation to physical condition and survival of the infants. The percentage of infants receiving a perfect score on a given task ranged from 30.6 (rooting) to 70.6% (grasping). Heavier infants were more likely to have perfect scores for crawling (F=4.20, P=0.044) and infants with a longer knee–heel length tended to be more likely to have a perfect grasping score (F=3.63, P=0.06). While the modal score was a perfect score for most individual tasks, the modal number of total perfect scores that a given infant received was 3–4 and only 4.7% of infants received perfect scores on all seven tasks. These results suggest that this group of behavioral tasks will produce a variable response within a population of neonates. While no individual behavioral score predicted survival during week 1, the number of perfect scores across all tasks was predictive of survival outcome; infants with a higher total number of perfect scores were more likely to survive (F=6.02, P=0.018). When all combinations of tests were compared, the best predictor of survival was outcome on four of the seven tests, all related to motor skills (F=7.46, P=0.009).
Thermodynamic studies of some Fe‐Pt alloys by the solid electrolyte galvanic cell method
Authors: Fredriksson Patrik , Seetharaman Seshadri
Published: March 2003

In the present investigation, the thermodynamic activities of iron in iron‐platinum solid alloys were measured by the solid electrolyte galvanic cell method in the temperature range 1073–1273 K. The galvanic cell employed can be represented as

(−) Pt, Fe(s), FetO(s) // ZrO2(11 mol pct CaO) //

FetO(s), Fe‐Pt alloys, Pt(+)

The experimental set‐up as well as the satisfactory performance of the galvanic cell were validated by measuring the standard Gibbs energy of formation of CoO in equilibrium with Co in the same temperature range by replacing the working electrode by a Co, CoO mixture. 6 different Fe‐Pt alloys covering the entire composition range were studied and the results are compared with earlier thermodynamic studies available in the literature. The present experimental results are found to be in general agreement with those of Alcock and Kubik. The values were fitted into a regular solution description in order to estimate the enthalpies of mixing Pt and Fe in the solid alloys.
Experimental and demographic analyses of growth rate and sexual size dimorphism in a lizard, Sceloporus undulatus
Authors: Haenel Gregory J. , John‐Alder Henry B.
Published: March 2003

Sexual size dimorphism (SSD) is a common phenomenon caused by a variety of environmental and genetic mechanisms in animals. In the current study, we investigate the demography of a population of eastern fence lizards (Sceloporus undulatus) to compare age structure and survivorship between the sexes, and we examine growth rates of juveniles under both natural and controlled laboratory conditions to elucidate causes of SSD in this species. Furthermore, using our laboratory growth data, we examine the heritability of juvenile growth rates. Our results show that SSD develops in the field before the end of the first year of age (before sexual maturity) because juvenile females grow more rapidly than juvenile males. In the laboratory environment, however, we observed no sexual difference in growth rates for lizards up to the size of maturity in the field. Thus, sexual differences in growth rate and subsequent development of SSD in this population are highly plastic and subject to strong proximal control. We found high levels of additive genetic variance for juvenile growth, indicating a strong potential for selection to operate on juvenile growth rates. Our results indicate that selection on juvenile growth rate could account for differences in growth among populations but would not necessarily contribute to SSD within our population due to the high plasticity in growth rate.
The spatial distribution of plant populations, disease dynamics and evolution of resistance
Authors: Carlsson‐Granér Ulla , Thrall Peter H.
Published: March 2003

Empirical studies of the interaction between the anther smut fungus Microbotryum violaceum and its host plant Lychnis alpina were combined with modelling approaches to investigate how variation in the spatial distribution of host populations influences disease dynamics and variation in resistance. Patterns of disease incidence and prevalence were surveyed in three contrasting systems of natural L. alpina populations where there is substantial variation in spatial structure, ranging from large continuous populations through to small isolated patches. Disease incidence (fraction of populations where disease was present) was highest in the continuous situation, and lowest in the most isolated populations. The reverse was true for prevalence (fraction of individuals diseased). To better understand the long‐term ecological and evolutionary consequences of differences in among population spatial structure, we developed a two‐dimensional spatially explicit simulation model in which host‐population spacing was modelled by varying the percentage of sites suitable for the host. The general patterns of disease incidence and prevalence generated in the simulations corresponded well with the patterns observed in natural populations of L. alpina and M. violaceum; i.e. the fraction of sites with disease increased while the average disease prevalence in diseased populations decreased when host populations became more connected. One likely explanation for the differences in disease incidence and prevalence seen in natural populations is that the evolution of host resistance varies as a function of the degree of fragmentation. This is supported by simulation results that were qualitatively similar to the survey data when resistance was allowed to vary, but not when hosts were assumed to be uniformly susceptible. In the former, the frequency of resistance increased markedly as host populations became more connected.
Plastic sex‐roles in the common goby – the effect of nest availability
Authors: Borg Åsa A. , Forsgren Elisabet , Magnhagen Carin
Published: March 2003

One of the most important factors shaping animal sex‐roles is the operational sex ratio, since a skew of this ratio promotes mating competition in the more abundant sex. In this study, we wanted to see if a change in sex‐roles, related to an environmental induced change in operational sex ratio, could be demonstrated in a field situation. Common goby (Pomatoschistus microps) males build nests under bivalve shells and provide exclusive parental care. Therefore, available nest sites are crucial for successful breeding in this species and should also affect the operational sex ratio. We addressed the question of whether the availability of nest sites, through an effect on the operational sex ratio, affects courtship and mating competition in the common goby. We increased nest site availability in the field by adding potential nest material (bivalve shells) to one location. We then compared the reproductive behaviour of the gobies at this and another location with lower nest site abundance. In general, the reproductive behaviour differed as predicted. Under nest shortage, males occupied new nests and received eggs faster than under nest excess. Behavioural observations of nests revealed that males initiated courtship more often than females where nest sites were abundant, whereas female courtship dominated where nests were scarce. Males more often rejected females attempting to enter their nests under nest shortage, male sneaking attempts were also more common in this bay. Male‐male aggression was frequent at both locations, whereas agonistic interactions between females only occurred in the nest shortage bay. Thus, males should be subject to sexual selection in both bays even though courtship roles differed. These results suggest that nest site availability affects mating competition and courtship roles in the common goby.
The adaptive significance of autumn leaf colours
Authors: Wilkinson David M. , Sherratt Thomas N. , Phillip Denise M. , Wratten Stephen D. , Dixon Anthony F. G. , Young Andrew J.
Published: March 2003

Recently W.D. Hamilton and colleagues proposed a provocative new theory to explain the adaptive significance of autumnal leaf colours. They suggested that these colours were signals produced by the trees to warn potential insect herbivores of their defensive ability and tested this theory by an analysis of data on aphid species richness on different tree species. Here we argue that the principal assumptions of their theory do not match current knowledge of plant pigment biochemistry and aphid ecology. We therefore present further adaptive explanations for autumn leaf colours and suggest alternative reasons for the reported relationship between tree leaf colour and aphid species richness.
Expression of apoptotic signaling proteins in leukoplakia and oral lichen planus: quantitative and topographical studies
Authors: Tanda Naoko , Mori Shiro , Saito Keiichi , Ikawa Kyoko , Sakamoto Seizaburo
Published: March 2003

Abstract: Although the pathogenesis of leukoplakia has been unclear, carcinogenic transformation is postulated to result from alterations of apoptotic signal transduction proteins in epithelial cells. The pathogenesis of oral lichen planus (OLP) has also been unclear, but apoptotic changes of the epithelial cells in OLP have been reported. In the present study, we used a histochemical approach to describe human keratinocyte‐expression of several apoptotic signaling proteins in leukoplakia, in OLP, and in normal oral mucosa as a control. Mucosal biopsies from patients with leukoplakia (n=13), OLP (n=10), and normal oral mucosa (n=9) were frozen, sectioned and immunostained with monoclonal antibodies to wild‐type (wt) tumor suppressive protein p53, cyclin‐dependent kinase inhibitor p21WAF1/CIP1 and the oncoproteins MDM2, and Bcl‐2. Apoptosis was assessed in all cases by the TUNEL method. MDM2 and Bcl‐2 expression in keratinocytes were quantitatively greater in leukoplakia than in OLP. Wt‐p53 and p21WAF1/CIP1 expression was quantitatively greater in keratinocytes in OLP than in leukoplakia. Keratinocyte maturation appeared histologically normal in OLP, even though wt‐p53 and p21WAF1/CIP1 were expressed in these cells. Altered keratinocyte maturation was seen in leukoplakia lesions expressing MDM2 and Bcl‐2. No significant difference for the number of apoptotic epithelial cells was observed between leukoplakia and OLP, in spite of the divergent outcomes of the apoptotic signaling proteins.
Alendronate‐related oral mucosa ulcerations
Authors: Gonzalez‐Moles Miguel Angel , Bagan‐Sebastian Jose Vicente
Published: March 2003

Abstract: Alendronate is widely used in the treatment of osteoporosis and other bone diseases. Although it is considered a well‐tolerated drug, there are numerous reports of adverse effects on the mucosa in the upper aerodigestive tract, with oesophagitis as the most common complication. The strict regulations for the proper administration of the drug indicate that these side effects might well be the result of a direct, irritant mechanism on the upper aerodigestive tract. We present two clinical cases of patients who developed extensive palatal ulcers as a result of taking alendronate. We discuss possible mechanisms implicated in the production of the ulcers and some clinical factors of interest.
The secretion of amelogenins is associated with the induction of enamel and dentinoid in an ameloblastic fibro‐odontoma
Authors: Yagishita Hisao , Taya Yuji , Kanri Yoriaki , Matsuo Akira , Nonaka Hiroko , Fujita Hiroki , Aoba Takaaki
Published: March 2003

Abstract: Ameloblastic fibro‐odontoma is the unique entity of epithelial–ectomesenchymal odontogenic tumors, which is characterized by enamel formation in addition to dentine. We examined immunohistochemically a case of this tumor in which enamel having prism structures was developed in the absence of odontoblast differentiation but was in contact with mesenchymal matrices. Histological examination showed diverse morphological features of epithelial tumor cells, e.g., cuboidal cells comprising tooth bud‐like projections, ameloblast‐ and stellate reticulum‐like cells, and residual cells in forms of extended cords or islands of odontogenic epitheilium. Immunostaining with anti‐amelogenin sera proved that the intracellular production of amelogenins was initiated at the tooth bud‐like stage. The secreted amelogenins were detected almost exclusively in the induced enamel and dentinoid areas, as well as in the core region of cementicle‐like spheres deposited in the encapsulating stroma. The results obtained indicate that the odontogenic tumor epithelia and its products, i.e., amelogenins, participate in multifaceted aspects of dental hard tissue formation that takes place during oncogenesis.
Interferon gamma (IFN‐γ) may reverse oral submucous fibrosis
Authors: Haque M. F. , Meghji S. , Nazir R. , Harris M.
Published: March 2003

Abstract: Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity and oropharyngx characterised by fibrosis in the submucosa leading to progressive limitation of the mouth opening. Interferon gamma (IFN‐γ) is a known anti‐fibrotic cytokine. In this study we have investigated: a) the effect of IFN‐γ on collagen synthesis by arecoline‐stimulated OSF fibroblasts in vitro (n=5), b) the effect of intra‐lesional IFN‐γ on the fibrosis of OSF patients (n=29) and c) the immunohistochemical analysis of pre‐ and post‐treatment inflammatory cell infiltrates and cytokine levels in the lesional tissue (n=29). The results show that the increased collagen synthesis in vitro in response to arecoline was inhibited in the presence of IFN‐γ (0.01–10.0 U/ml) in a dose‐related way. In an open uncontrolled study intra‐lesional IFN‐γ treatment showed improvement in the patients mouth opening from an inter‐incisal distance before treatment of 21±7 mm, to 30±7 mm immediately after treatment and 30±8 mm 6‐months later, giving a net gain of 8±4 mm (42%) (range 4–15 mm). Patients also reported reduced burning dysaesthesia and increased suppleness of the buccal mucosa. The post‐treatment immunohistochemistry showed a decreased amount of inflammatory cell infiltrate and an altered level of cytokines compared with the pre‐treatment lesional tissue. The effect of IFN‐γ on collagen synthesis appears to be a key to the treatment of these patients, and intra‐lesional injections of the cytokine may have a significant therapeutic effect on OSF.
The effect of desalivation on 4‐nitroquinoline‐1‐oxide‐induced tongue carcinogenesis: a morphometric study of nucleolar organizer regions
Authors: Kaplan Ilana , Engelberg Judith , Dayan Dan
Published: March 2003

Abstract: Saliva is an important factor in the oral cavity and could be significant in protecting against carcinogens. In experimental models of carcinogenesis, saliva was shown to have a temporary protective effect against the carcinogens DMBA and 4‐nitroquinoline‐oxide (4NQO). Silver‐stained nucleolar organizer regions (AgNORs) are considered markers for both proliferative capacity and prognosis. The purpose of the present study was to investigate the effect of desalivation on AgNOR parameters in lesions induced by the carcinogen 4NQO in a rat model, in order to trace early nuclear changes. The study group consisted of 120 male Wistar‐derived rats. The experimental group (n=56) underwent surgical desalivation; the control group (n=56) underwent a sham operation, and both groups were administered a solution of 0.001% 4NQO in the drinking water. A normal group (n=8) did not receive surgery and drank tap water. Rats were sacrificed at 7, 14, 22, and 28 weeks. Formalin fixed, paraffin embedded sections of the tongue were silver‐stained and AgNOR parameters were analyzed using computerized image analysis. In both desalivated and control groups, the nuclear area was significantly higher than the normal. This difference was already evident at 7 weeks. The mean AgNOR area was significantly higher in the desalivated group at week 7 and continued to increase over time. The mean AgNOR number was also significantly higher in the desalivated group at week 7. Differences between the desalivated and control groups diminished with time. These changes in proliferative activity, as expressed by AgNOR parameters, presented earlier changes in comparison to those observed in microscopic examination of the same slides. Results suggest that saliva in the oral cavity can delay malignant transformation, but continued exposure to the carcinogen overrides this effect. AgNOR stain seems to be sensitive and allows for early identification of intranuclear changes.