bluuebunny/crossref_metadata_2025 huggingface dataset:
Nod factors stimulate plasma membrane delimited phospholipase C activity in vitro
Authors: Kelly Marilyn N. , Irving Helen R.
Published: March 2003

Nod factors are lipo‐chito‐oligosaccharides secreted by Rhizobium to initiate deformation of root hairs and other changes in host plants. Since Nod factor‐induced changes in intracellular calcium occur in responsive root hairs, we tested if phospholipase C (PLC) activity is stimulated by Nod factors. Plasma membranes were isolated from the nodulation‐competent zone of roots of Vigna unguiculata to assay PLC activity in vitro. Nod factors isolated from Rhizobium sp. NGR234, NodNGR[S] and NodNGR[Ac] significantly increased PLC activity and this increase in activity was inhibited in the presence of the PLC inhibitors, neomycin and U‐73122. The response appears specific as PLC activity was not significantly induced neither by the 4‐sugar, N,N′,N′′,N′′′‐tetracetylchitotetraose (TACT), or the five‐sugar, penta‐N‐acetylchitopentaose (PACT), backbone of Nod factors. The G‐protein activators, GTPγS and the aluminium fluoride complex, had no effect on PLC activity in the presence or absence of NodNGR[S], suggesting that Nod factors act independently of G‐proteins in vitro. However, the combination of oleic acid and TACT mimicked the effect of Nod factors on PLC activity indicating that the presence of the lipid tail may be critical. Also this combination of compounds acted synergistically together to evoke root hair deformation in vivo. Our results indicate that Nod factors can modulate membrane delimited PLC activity and indicate that PLC is likely to be a component of the Nod factor‐signalling pathway.
Activity of enzymatic antioxidant defense systems in chilled and heat shocked cucumber seedling radicles
Authors: Kang Ho‐Min , Saltveit Mikal E.
Published: March 2003

Chilling whole cucumber seedlings that had 10‐mm long radicles for 4 days at 2.5°C significantly inhibited subsequent radicle growth both by increasing the time it took the seedlings to recover from chilling and attain a linear rate of radicle growth, and by decreasing the subsequent rate of linear growth. Exposing cucumber seedlings to 45°C for up to 20 min had no effect on subsequent radicle growth, while longer exposures produced reductions in growth. A heat shock at 45°C for 10 min induced the optimal protection to 4 days of chilling at 2.5°C by reducing chilling inhibition from 60 to 42%. Two hours after being chilled, heat shocked or heat shocked and then chilled, there was no difference in protein content of the apical 1 cm of the seedling radicle among these treatments and the non‐heat shocked, non‐chilled control. Two days after treatment, the protein content was still similar in tissue that had been heat shocked or heat shocked and chilled, while it was significantly reduced in tissue that had been chilled. In general, 2 h after treatment, the activity of the 5 antioxidant enzymes examined in this study [superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), guaiacol peroxidase (GPX; EC 1.11.1.7) and glutathione reductase (GR; EC 1.6.4.2)] were reduced by chilling and unaffected or increased by heat shock. When heat shock was followed by chilling, there was a consistent effect of the heat shock treatment on preventing the loss of enzyme activity following chilling. This protective effect of the heat shock treatment was even more pronounced after 2 days of recovery at 25°C for SOD, CAT and APX. In contrast, the activity of GR and GPX was substantially higher in chilled tissue than in tissue that had been heat shocked before being chilled. Elevated levels of GR and GPX therefore appear to be correlated with the development of chilling injury, while elevated levels of SOD, CAT and APX appear to be correlated with the development of heat shock‐induced chilling tolerance.
A seedling specific vegetative lectin gene is related to development in Cicer arietinum
Authors: Esteban Rocío , Dopico Berta , Muñoz Francisco J. , Romo Silvia , Labrador Emilia
Published: March 2003

Plant lectins are a group of glycoproteins with the ability to recognize and bind carbohydrate ligands. Seed lectins function as storage and defense proteins, but the specific function of vegetative lectins is uncertain. In this paper we describe the characterization of a clone, CanVLEC, encoding a vegetative lectin from chickpea (Cicer arietinum L. cv. Castellana). The expression of the CanVLEC gene was specific in seedlings, mostly in hooks and elongating epicotyls, and no expression was detected in adult plants. The level of chickpea vegetative lectin transcripts in epicotyls decreased through the epicotyl growth suggesting a relationship to development. Treatment with indoleacetic acid (IAA) and brassinolides (BR), hormones that promoted elongation in chickpea epicotyl, increased the level of CanVLEC mRNA, supporting a relationship to growth. CanVLEC is drastically down regulated by water deficit ruling out its possible involvement in plant response to water stress, unlike other vegetative lectins. CanVLEC protein may be targeted to an extracellular location owing to the presence of a signal peptide.
A CDPK type protein kinase is involved in rice SPS light modulation
Authors: Pagnussat Gabriela C. , Fiol Diego F. , Salerno Graciela L.
Published: March 2003

A protein kinase activity that can phosphorylate and inactivate rice (Oryza sativa) sucrose‐phosphate synthase (SPS; UDP‐glucose: d‐fructose‐6‐phosphate‐2‐glucosyl transferase, EC 2.4.1.14) was measured in extracts prepared from leaves exposed to light‐dark transitions. Enzyme activity present in extracts from dark leaves was about 5‐fold higher than the activity in extracts from leaves that had been collected in the light. The protein kinase (named R‐SPSK) was purified about 100‐fold from dark leaves and its biochemical properties were studied. The micromolar dependence of Ca2+ exhibited by R‐SPSK, and its response to calmodulin antagonists was similar to the properties associated with members of the plant Calcium‐Dependent Protein Kinase (CDPK) family. Two modulators of SPS activity, Pi and Glc‐6‐P, were examined for an effect on R‐SPSK. While Glc‐6‐P did not affect R‐SPSK activity, Pi drastically increased the kinase activity. Taken together, these data provide evidence that SPS may be regulated by a CDPK type protein‐kinase whose activity is modulated by light‐dark transitions and stimulated by Pi, the negative effector of SPS activity.
Reduced atmospheric CO2 inhibits nitrogen mobilization in Festuca rubra
Authors: Thornton Barry , Paterson Eric , Kingston‐Smith Alison H. , Bollard Andrea L. , Pratt Shona M. , Sim Allan
Published: March 2003

In defoliated grasses, where photosynthesis is reduced due to removal of leaf material, it is well established that remobilization of nitrogen occurs from both older remaining leaves and roots towards the younger growing leaves. In contrast, little is known about the movement of nitrogen within intact grass plants experiencing prolonged inhibition of photosynthesis. We tested the following hypotheses in Festuca rubra L. ssp. rubra cv. Boreal: that both reduction of the atmospheric CO2 concentration and defoliation (1) induce mobilization of nitrogen from roots and older leaves towards growing leaves and (2) elicit similar directional change in the abundance of proteins in roots and older leaves relevant to the process of nitrogen mobilization including, glutamine synthetase (GS), EC 6.3.1.2; papain, EC 3.4.22.2; chymopapain, EC 3.4.22.6; ribulose bisphosphate carboxylase/oxygenase (Rubisco), EC 4.1.1.39; and the light harvesting complex of photosystem II (LHCPII). After growth at ambient atmospheric CO2 concentration, plants of F. rubra were subject to atmospheres containing either ambient (350 µl l−1) or deplete (< 20 µl l−1) CO2. Concurrently, plants were either left intact or defoliated on one occasion. Steady state 15N labelling coupled with a series of destructive harvests over a 7‐day period enabled changes in the nitrogen dynamics of the plants to be established. Proteins pertinent to the process of nitrogen mobilization were quantified by immunoblotting. Irrespective of defoliation, plants in ambient CO2 mobilized nitrogen from older to growing leaves. This mobilization was inhibited by deplete CO2. Greater concentration of Rubisco and reduced chymopapain abundance in older remaining leaves of intact plants, in deplete compared with ambient CO2, suggested the inhibition of mobilization was due to inhibition of protein degradation, rather than to the export of degradation products. Both deplete CO2 and defoliation induced nitrogen mobilization from roots to growing leaves. In plants at ambient CO2, defoliation did not affect nitrogen uptake or its allocation. Therefore in F. rubra nitrogen mobilization can occur independently of any downregulation of nitrogen uptake. This suggests either different signal compounds may act to downregulate uptake and upregulate mobilization, or if one particular signalling compound is used its concentration threshold differs for induction of mobilization and downregulation of uptake. The abundance of the cysteine proteases papain and chymopapain was low in roots suggesting that they were not involved in protein degradation in this tissue.
Molecular evolution of carotenoid biosynthesis from bacteria to plants
Authors: Sandmann Gerhard
Published: March 2003

β‐Carotene and derivatives are important pigments in plant photosynthesis. They are found not only in green plants but also accumulate in archea, prokaryotes and fungi. For β‐carotene biosynthesis, enzymes are necessary to catalyse the formation of phytoene, several desaturation steps and cyclization reactions. This review is focused on the molecular phylogeny of the enzymes, the genes involved and their diversity. It outlines how genes and enzymes from prokaryotes and archea were modified to give rise to the corresponding plant constituents. In the cases of phytoene synthase, a direct line of evolution can be drawn. For other carotenogenic enzymes, new genes and enzymes have been acquired at certain stages of evolution. In addition, phytoene desaturases and lycopene cyclases are examples of convergent evolution of different types of enzymes, which are structurally completely unrelated but functionally identical. Finally, several gene duplications led to homologous enzymes with different catalytic functions including those involved in the synthesis of α‐carotene.
Cold induced expression of plant defensin and lipid transfer protein transcripts in winter wheat
Authors: Gaudet Denis A. , Laroche André , Frick Michele , Huel René , Puchalski Byron
Published: March 2003

In winter wheat, low temperature hardening induces a non‐specific resistance to snow moulds and other fungi. In a suppressive subtractive hybridization cDNA library between winter wheat unhardened and hardened at 2°C, 17% of 186 sequenced cDNA clones were homologous to the small plant defence related proteins, γ‐thionin, γ‐purothionin or non‐specific lipid transfer proteins (LTPs), based on their nucleotide sequences or deduced from amino acid sequences. Several partial‐ and full‐length cDNA clones homologous to two defensin proteins (γ‐thionin, subfamily B‐2, γ‐purothionin, subfamily I), and non‐specific LTPs were isolated. Regulation of defensin transcripts was clearly different from that of the LTPs under controlled environments in the field. The γ‐thionin and γ‐purothionin transcripts were not expressed in unhardened plants grown at 20°C, strongly upregulated after 1–3 days hardening at 2°C, remained upregulated for 28 days hardening, and disappeared following 1 day of exposure to dehardening conditions at 20°C. The LTPs transcripts were constitutively expressed in plants growing at 20°C, gradually increased to maximum levels following 14–28 days at hardening, and remained upregulated following 1 and 7 days dehardening. In the field, the γ‐thionin and γ‐purothionin transcripts rapidly increased to maximum levels by mid‐November and decreased gradually during the winter until mid‐March LTP transcripts were highly expressed in the early autumn, further increased during December–January, then decreased during late winter and early spring. Differences in the pattern and level of expression of these transcripts were evident among cultivars; γ‐thionin expression was associated with freezing resistance among the genotypes tested under both controlled environment and field conditions.
Reactivation of chronic Chagas’ disease following allogeneic bone marrow transplantation and successful pre‐emptive therapy with benznidazole
Authors: Altclas J. , Sinagra A. , Jaimovich G. , Salgueira C. , Luna C. , Requejo A. , Milovic V. , De Rissio A. , Feldman L. , Riarte A.
Published: March 2003

This report shows the early detection of reactivation of chronic Chagas’ disease (CCd) in a 27‐year‐old man with chronic myelogenous leukemia undergoing allogeneic bone marrow transplantation (ABMT). Pre‐emptive therapy with benznidazole during a period of 7 weeks led to a rapid recovery of the patient, who remains free of parasitemia 2 years after the bone marrow transplantation.
Hepatic arterial thrombosis due to Mucor species in a child following orthotopic liver transplantation
Authors: Marcó del Pont J. , De Cicco L. , Gallo G. , Llera J. , De Santibanez E. , D’Agostino D.
Published: March 2003

Infection is a frequent complication in patients following liver transplantation, and mycotic etiology is the third most common cause. Thrombosis of the hepatic artery is a high‐risk condition for the graft and is generally secondary to noninfectious diseases. We present a 2‐year‐old child who developed hepatic artery obstruction due to Mucor sp. The child did not respond to medical treatment. We conclude that a high index of suspicion and rapid diagnosis are required so that aggressive and early treatment can be initiated. To our knowledge this is the first case published with this particular association.
Microbiological diagnosis of invasive fungal infections in transplant recipients
Authors: Verweij P.E. , Meis J.F.G.M.
Published: March 2003

Invasive fungal infections remain an important cause of morbidity and mortality in transplant recipients. Since conventional diagnostic tools such as culture lack sensitivity and specificity, alternative diagnostic assays have been developed. Among the most promising techniques are the detection of fungal DNA and serology. Fungal DNA can be detected with high sensitivity and specificity when performed with specimens from sterile sites such as blood. Polymerase chain reaction (PCR) assays can be used to detect a broad range of fungal pathogens and combined with species identification. Multicenter diagnostic studies are needed to establish the diagnostic value of PCR but lack of standardization hampers such studies. The serodiagnosis of invasive fungal infections has become an important tool in the management of invasive fungal infections. Especially the detection of circulating galactomannan has been shown to be a sensitive marker for invasive aspergillosis. Both serology and PCR can be used to monitor the response to antifungal therapy. The optimal use of non‐culture‐based methods is in prospective screening of patients at high risk. Since the incidence of disease greatly influences the positive predictive value, screening should take place only in those patients at very high risk for invasive fungal disease.
Human granulocytic ehrlichiosis in a renal allograft recipient: review of the clinical spectrum of disease in solid organ transplant patients
Authors: Vannorsdall M.D. , Thomas S. , Smith R.P. , Zimmerman R. , Christman R. , Vella J.P. , Vannorsdall M.D. , Thomas S. , Smith R.P. , Zimmerman R. , Christman R. , Vella J.P.
Published: March 2003

Background. Ehrlichiosis is a recently described zoonotic infection with two major expressions: human granulocytic ehrlichiosis (HGE) and human monocytic ehrlichiosis (HME). The organisms associated with HGE and HME have been detected in a tick vector in several regions of United States and cases of ehrlichiosis have been reported in the general population. Methods. We report a case of HGE in a renal allograft recipient and review the clinical spectrum of disease in solid organ transplant recipients and the epidemiological basis for risk. Results. Our patient demonstrated the typical epidemiological, clinical and laboratory features of human granulocytic ehrlichiosis and responded to treatment with doxycycline. Conclusions. Human ehrlichiosis should be considered in the differential diagnosis of patients with solid organ transplants, who present with fever and thrombocytopenia. The incidence of ehrlichiosis in the solid organ transplant population is similar to that in the United States general population. As reported in immunocompetent patients, prompt diagnosis and treatment results in the rapid resolution of symptoms in transplanted individuals.
Suppression of T cells results in long‐term survival of mouse heart xenografts in C6‐deficient rats
Authors: Wu Guosheng , Korsgren Olle , Van Rooijen Nico , Tibell Annika
Published: March 2003

Abstract: The present study aimed to investigate the role of cellular immune response in the absence of membrane attack complex (MAC) formation in the concordant mouse‐to‐rat heart xenografting. Hearts from BALB/c mice were transplanted into the neck vessels of C6‐competent (C6+) and C6‐deficient (C6−) PVG rats. Liposome‐encapsulated dichloro‐methylene diphosphonate (Lip‐Cl2MDP) was administered at a dose of 10 ml/kg 2 days before transplantation and every 5 days thereafter. Cyclosporine (CsA) was administered intramuscularly (i.m.) at a dose of 15 mg/kg per day. The heart xenografts were harvested for immuno‐histological analysis at the time of rejection and the functioning grafts were removed at 70 days after transplantation. In untreated C6+ rats, xeno‐grafts survived for 2.3 ± 0.5 days. Treatment with CsA or Lip‐Cl2MDP in C6+ rats did not significantly affect graft survival (2.5 ± 0.6 and 2.3 ± 0.4 days, respectively). In untreated C6− rats, xenografts survived for 5.0 ± 0.6 days. However, Lip‐Cl2MDP in C6− rats resulted in a prolongation of graft survival to 11 ± 2.3 days (P < 0.05 vs. untreated C6− rats), while treatment with CsA alone in these rats led to more than 70 days' survival in four out of six grafts (61 ± 16 days). In untreated C6+ rats, immunohistology showed a severe myocardial necrosis and thrombosis with a scarce cellular infiltrate in the rejected xenografts. By contrast, in untreated C6− rats, xenografts were heavily infiltrated by macrophages and T cells. The number of macrophages, but not T cells, was markedly reduced in Lip‐Cl2MDP‐treated rats. In CsA‐treated C6− rats, the grafts harvested at 70 days after transplantation had a normal morphology, with a minimal cellular infiltrate. Our data indicate that MAC‐mediated injury plays an essential role in concordant xenograft rejection. Once this mechanism has been prevented, suppression of T cells allows for long‐term xenograft survival.
Spectrotype analysis and clonal characteristics of human anti‐Gal alpha1–3Gal antibodies
Authors: Tinguely Caroline , Schaller Monica , Carrel Thierry , Nydegger Urs E.
Published: March 2003

Galα1–3Gal (anti‐Gal), a polyclonal so‐called natural antibody (Ab), is present in large amounts in human serum not only as IgG‐, but also as IgM‐ and IgA‐isotypes. It has gained a particular interest in the context of xenotransplantation, because the endothelial pig cells express the terminal Galα1–3Gal determinant on several adhesion molecules. Little is known of it's function and direct examination of the structure of the Ig genes responsible for coding anti‐Gal is lacking. We used the technique of isoelectric focussing (IEF)/affinity immunoblotting for direct analysis of the clonal distribution and spectrotype analysis of IgM‐ and IgG anti‐Gal. By single cell analysis of magnetic bead and fluorescent‐activated cell sorter (FACS) isolated mature anti‐Gal bearing human B cells from whole blood we analyzed the VH gene families involved in anti‐Gal production. Oligoclonal and individually distinct IgG banding patterns were found with isoelectric points between 4 and 9. IgM spectrotypes revealed to be more uniform with a polyclonal banding pattern of more than 12 bands at a pH between 4.7 and 7. IgG‐ and IgM‐banding patterns over a period of 6 months remained unchanged. Single cell polymerase chain reaction (PCR), with all family specific primers, revealed the use of the VH2f gene family for the IgG2 isoptype. The differences found in the spectrotype banding patterns of IgG and IgM could be explained by the suggestion that anti‐Gal IgM were produced by the use of unmutated germline genes and the possibility of the absence of somatic mutations. The greater clonal heterogeneity in the IgG population could be explained by somatic hypermutations during the switch from IgM to IgG. The use of this VH2f gene family, which is also involved in the generation of Abs against bacterial pathogens, could mean that this is a predominant region used for the generation of such natural occurring antibodies.
Anti‐pig antibody levels in naïve baboons and cynomolgus monkeys
Authors: Holmes Beverly J. , Richards Andrew C. , Awwad Michel , Copeman Laura S. , Mclaughlin Megan L. , Cozzi Emanuele , Schuurman Henk‐Jan , Davies Hugh F. S.
Published: March 2003

Anti‐pig antibodies (APA) were analysed in serum from 28 naïve wild‐caught baboons (originating from Kenya) and 31 naïve captive‐bred cynomolgus monkeys (13 from the Philippines and 18 from Mauritius), using a haemolytic assay with pig erythrocytes (APA), flow cytometry on the porcine lymphoma T‐cell cell line L35, and enzyme linked immunosorbent assay (ELISA) using α‐Gal type II and type VI antigen. This was extended in baboon samples by the evaluation in two laboratories (Imutran, Cambridge, UK and Immerge, Boston, USA), and by antibody absorption using either immobilized α‐Gal type II or α‐Gal type VI. Anti‐porcine antibodies were demonstrated in all assays with substantial variability within and between the three non‐human primate groups. Immunoglobulin (Ig)M antibody levels tended to be similar to or higher than those in a pooled normal human standard serum while IgG levels tended to be lower. Highest antibody levels were recorded in Mauritius cynomolgus monkeys. There were statistically significant correlations between assays for IgM or IgG class anti‐Gal antibodies using either α‐Gal type II or α‐Gal type VI as antigen, both for different assays and two laboratories involved. Also, significant correlations were observed between the anti‐Gal and L35 binding assays. Baboon sera before and after absorption to immobilized α‐Gal type II or type VI were analysed for anti‐Gal type VI or type II antibody: levels were almost undetectable indicating that most anti‐Gal antibodies react to epitopes shared between α‐Gal type II and type VI oligosaccharides. Finally, the relation between APA and outcome of porcine heart xenotransplantation in cynomolgus monkeys and baboons showed no apparent relation between pre‐transplant APA levels and the occurrence of hyperacute rejection (HAR) when compared with non‐immunological cause of organ/recipient dysfunction or acute humoral xenograft rejection during the first 4 days post‐transplantation or survival exceeding 4 days post‐transplantation.
Cleft lip with or without cleft palate and dermatoglyphic asymmetry: evaluation of a Chinese population
Authors: Neiswanger K , Cooper ME , Weinberg SM , Flodman P , Keglovits A Bundens , Liu Y , Hu D‐N , Melnick M , Spence MA , Marazita ML
Published: March 2003

Structured Abstract

Authors –Neiswanger K, Cooper ME, Weinberg SM, Flodman P, Bundens Keglovits A, Liu Y, Hu D‐N, Melnick M, Spence MA, Marazita ML

Objective –To determine if Chinese individuals with non syndromic cleft lip with or without cleft palate (CL/P) display more dermatoglyphic asymmetry than unaffected relatives or controls.

Design –Case – control study with two control groups (genetically related and unrelated).

Setting and Sample Population –A total of 500 CL/P probands from Shanghai, China, 421 unaffected relatives, and 66 controls of Chinese heritage.

Methods –Finger and palm prints were collected, and pattern frequencies, total ridge counts (TRC), and atdangles were calculated. Asymmetry scores between right and left hands were defined for each of the three dermatoglyphic measures. Probands' asymmetry scores were compared statistically with the scores of unaffected relatives and controls.

Results –In general, the probands' asymmetry scores for TRC and atdangle did not differ significantly from the scores of either unaffected relatives or controls. However, probands with a positive family history of clefting showed significantly more asymmetry in their pattern types than either probands without a family history, unaffected relatives or controls.

Conclusion –These results suggest that a unique genetic mechanism of developmental instability may obtain in CL/P individuals with a positive family history of clefting.
Distribution of fibroblast growth factors (FGFR‐1 and ‐3) and platelet‐derived growth factor receptors (PDGFR) in the rat mandibular condyle during growth
Authors: Visnapuu V , Peltomäki T , Rönning O , Vahlberg T , Helenius H
Published: March 2003

Structured Abstract

Authors –
Visnapuu V, Peltomäki T, Rönning O, Vahlberg T, Helenius H

Objectives –
To elucidate the role of the fibroblast growth factors 1 and 3 (FGFR‐1, ‐3) and the platelet derived growth factor (PDGFR) in the growth of the mandibular condylar cartilage in the rat.

Setting and sample population –
Institute of Dentistry and Department of Biostatistics, University of Turku, Turku, Finland. The material consisted of 1‐ to 21‐day‐old Long–Evans/Turku rats (total of 24 animals, three in each age group).

Design – An immunohistological in vivo study combined with histomorphometry and biostatistical analysis.

Experimental variable – The animals were killed with an overdose of carbon dioxide and thereafter decapitated. Heads were fixed in 4% paraformaldehyde, decalcified in 12.5% ethylenediaminetetraacetic acid, cut sagittally into two halves and sectioned sagittally at 6 μm. In order to detect FGFR‐1, ‐3 and PDGFR the sections were treated with H2O2/methanol (1:100), after which FGFR‐1 and PDGFR monoclonal and FGFR‐3 polyclonal antibodies were applied. The reaction products were visualized by using the Vectastain ABC Elite Kit using peroxidase substrate kit DAB as substrate. Negative and positive controls were also prepared. The sections were counterstained with hematoxylin.

Outcome measure –
In order to measure the depth of the cell layer labeled with FGF‐1, ‐3 and PDGF receptors, the condylar head was divided into four regions: anterior, superior, posterosuperior and posterior. The measurements were made perpendicular to the articular surface using a computerized image analysis system, the images being acquired by means of a microscope connected to a CCD camera. The mean of five equally distributed measurements of each region was used to indicate the depth of the cell layers secreting the receptors. Regression analysis was used to evaluate the association between the depth of the labeled cell layer in relation to total depth of the condylar head, as a function of age.

Results –
Our results show that the depth of the cell layer labeled for FGFR‐1, ‐3 and PDGFR increase significantly as a function of age in the mandibular condylar head of rats.

Conclusion –
Increase in the cell layer labeled for FGFR‐1, ‐3 and PDGFR occurs during the stage when the articular function of the mandibular condyle intensifies. FGFR‐1, ‐3 and PDGFR evidently have an important role in the growth regulation of the condylar cartilage during the most rapid growth period in the rat.
The discovery of linkage between the MHC and genetic control of the immune response
Authors: McDevitt Hugh
Published: March 2003

Summary: Immunization of rabbits, and inbred strains of mice with branched, multichain, synthetic polypeptides, such as (T, G) − A‐‐L and (H, G) − A‐‐L, revealed striking differences in the ability of different strains of mice to produce specific antibody. F1 and F1 × parental backcross mice revealed clear genetic control. Initial attempts to link this genetic control to known genetic markers were unsuccessful. The second approach, which attempted to transfer response from high or immediate responders into low responder recipients, initially encountered graft vs. host and host vs. graft reactions. The transfer of F1 spleen cells into the low responder parent demonstrated that ability to respond was a property of immunocompetent cells (spleen cells), not of the recipient's background genes. Mapping studies with recombinant H2 haplotype congenic strains, and a classic 4‐point mapping cross were concordant in placing the gene controlling this trait within the H2 complex, between the K and Ss loci. Subsequent studies mapped the genes for stimulation in the mixed lymphocyte culture reaction to the same position, suggesting cell surface expression. Production of antisera to ‘I‐region’ products defined ‘Ia’ antigens, the 2‐chain α/β MHC class II molecules.
Plasticity of hematopoietic stem cells and cellular memory
Authors: Avots Andris , Harder Friedrich , Schmittwolf Carolin , Petrovic Suzana , Müller Albrecht M.
Published: March 2003

Summary: Stem cell systems represent an effective and powerful approach for tissue development and regeneration of diverse tissue types. Common and defining features of these exceptional cells are the capacity for self‐renewal and the potential for differentiation into multiple mature cell types. Recently, surprising new observations have indicated that stem cells isolated from one adult tissue can also give rise to mature cells of other cell lineages, irrespective of classical germ layer designations. This discovery has resulted in quantum leaps in both scientific knowledge and the potential applications of stem cells. The new findings contradict central dogmas of commitment and differentiation of stem and progenitor cells. However, the true potential of somatic stem cells is just emerging and the new findings have to be defined more fully and integrated into a unifying model of stem cell potential and behavior. Here we analyze the developmental potential of hematopoietic stem cells of mouse and man following their injection into the murine preimplantation blastocyst, an environment that allows the development of all cell lineages. In addition, we discuss the emerging lines of evidence of the developmental plasticity of hematopoietic and other somatic stem cells and consider how cellular memory of transcriptional states is established and may be potentially involved in this phenomenon.
Imaging of T‐cell interactions with antigen presenting cells in culture and in intact lymphoid tissue
Authors: Delon Jérôme , Stoll Sabine , Germain Ronald N.
Published: March 2003

Summary: The development of an effective immune response requires cell–cell contact between T cells and antigen‐bearing cells of several types (dendritic cells, B cells, infected tissue cells). Recent advances in light microscopy have led to intense investigation of the molecular events that accompany these cell interactions, especially the redistribution of membrane proteins into discrete organized subdomains within the zone of cell–cell contact termed the ‘immunological synapse’. Here we discuss two aspects of our own studies in this area. First, we highlight results from our in vitro analysis of the role of the cytoskeletal ezrin, radixin, moesin adapter proteins in the exclusion of CD43 from the well‐defined T cell receptor (TCR) and integrin‐rich zones of the synapse. Based on the molecular mechanism uncovered in this work, we propose a new model for how TCR‐signaled changes in cytoskeletal organization indirectly influence both protein distributions and the efficiency of signaling between T cell and presenting cell. We then discuss the development of a new method for dynamic visualization of T cell – dendritic cell interactions in intact lymphoid tissue. The remarkable longevity of monogamous lymphocyte‐presenting cell interactions is discussed, differences between our observations and those of others are laid out in detail, and prospects for future application of this technical approach to analysis of early immune responses in lymphoid organs and of effector lymphocyte function in tissues are presented.
The role of hepatic peroxisome proliferator‐activated receptors (PPARs) in health and disease
Authors: Everett Lynn , Galli Andrea , Crabb David
Published: March 2003

Abstract: The liver has long been known to respond to exposure to certain chemicals with hyperplasia and proliferation of the peroxisomal compartment. This response is now known to be mediated by specific receptors. The peroxisome proliferator‐activated receptors (PPARs) were cloned 10 years ago, and in that interval, have been found to serve as receptors for a number of endogenous lipid compounds, in addition to the peroxisome proliferators that originally led to their study. Three receptors, designated the α, δ, and γ receptors, have been found in mammals. PPARα is the most abundant form found in the liver, with smaller amounts of the δ and γ forms also expressed there. Kupffer cells, like other macrophages, appear to express the α and γ isoforms. Hepatic stellate cells are reported to express the γ isoform. PPARα knock‐out mice fail to undergo peroxisome proliferation when challenged with the proliferators. Moreover, they have severe derangements of lipid metabolism, particularly during fasting, indicating that normal function of the alpha receptors is needed for lipid homeostasis. This in turn suggests that inadequate PPAR‐mediated responses may contribute to abnormal fatty acid metabolism in alcoholic and non‐alcoholic steatohepatitis. Recent information suggests that PPARγ receptors may be important in control of the activation state of the stellate cells, and their repression or inactivation may predispose to hepatic fibrosis. The first approved drug that specifically activates PPARγ, troglitazone, has rarely been found to cause serious liver injury. Although this is likely to represent an idiosyncratic reaction, the medical community will need to be alert to the possibility that activation or blockade of these receptors may cause hepatic dysfunction.
Efficacy and safety of an intravenous monoclonal anti‐HBs in chronic hepatitis B patients
Authors: Van Nunen Andeltje B. , Baumann Matthias , Manns Michael P. , Reichen J. , Spengler U. , Marschner Jens‐Peter , De Man Robert A.
Published: March 2003

Abstract: Background/Aims: In this study the safety and efficacy of a monoclonal anti‐HBs, Tuvirumab (Mab), were investigated. Tuvirumab is a human monoclonal antibody recognizing the stable ‘a’‐determinant of the HBsAg. Methods: We included ten chronic hepatitis B patients: four received monotherapy, and six combination therapy with interferon alpha 2b. Results: Because the development of insoluble [HBsAg–HBsAb] complexes led to adverse events, the Mab dose had to be reduced in seven patients. In nine patients treatment was stopped prematurely because of lack of efficacy, i.e. neutralization of HBsAg in serum. However, temporary HBsAg levels were reduced by at least 50% in all patients; in three patients receiving combination therapy, background levels of HBsAg in serum were reached. A loss of serum HBV‐DNA was seen in three patients in the combination group, followed by HBeAg seroconversion in two patients. Conclusions: We conclude that Mab was not effective in achieving primary efficacy as assessed by neutralization of circulating HBsAg. Whether a combination of Mab with an antiviral agent that reduces the HBsAg load – and therefore minimizes the risk of adverse events – may result in clinical efficacy should be investigated.
Sinusoidal endothelial cell injury by superoxide anion and iron in the Propionibacterium acnes‐pretreated and lipopolysaccharide‐stimulated rat liver
Authors: Hasegawa Tadashi , Nakano Minoru , Hashimoto Takashi , Hiraishi Katsuya , Suzuki Keiji , Kuwano Hiroyuki
Published: March 2003

Abstract: Aims/Background: We attempted to measure the generation of superoxide anion, examine its site of release and determine its pathological role in Propionibacterium acnes‐lipopolysaccharide‐induced liver injury in the rat. Methods: The P. acnes‐pretreated (16 mg/kg i.v.) rat liver was perfused with buffer containing lipopolysaccharide (2.5 μg/ml). Chemiluminescence enhanced with Cypridina luciferin analog, MCLA, and reduction of nitro blue tetrazolium were used for detecting superoxide anion. Leakage of enzymes and release of cytokines into the perfusate, and histological specimens were also examined. Results: Superoxide dismutase‐inhibitable chemiluminescence peaked at 30 min of lipopolysaccharide infusion and blue formazan precipitate was histochemically deposited mainly on hepatic macrophages. Purine nucleoside phosphorylase (PNP) activity in the perfusate, as a marker of sinusoidal endothelial cell injury, reached its maximum at 50 min and aspartate aminotransferase (AST) activity, as a marker of hepatocyte injury, reached a plateau at 90 min. Simultaneous treatment with superoxide dismutase and deferoxamine mesylate significantly suppressed the leakage of PNP and AST. Release of tumor necrosis factor‐α and growth‐related oncogene/cytokine‐induced neutrophil chemoattractant‐1 lagged behind PNP leakage. Light microscopy showed destruction of the sinusoids followed by hepatocyte necrosis. Electron microscopy revealed adherence of hepatic macrophages to sinusoidal endothelial cells. Conclusion: These results indicate that superoxide anion released from hepatic macrophages may induce sinusoidal endothelial cell injury via interaction with iron in the P. acnes‐lipopolysaccharide‐treated liver.
The effect of insulin and glucagon on splanchnic oxygen consumption
Authors: Simonsen Lene , Coker Robert , A. L. Mulla Nariman , Kjær Michael , Bülow Jens
Published: March 2003

Abstract: The purpose of these experiments was to measure the influence of insulin and glucagon on the splanchnic oxygen consumption. Two experiments were performed. Methods: In one experiment, the influence of hyperinsulinaemia was investigated in six healthy subjects, who were studied during a euglycaemic hyperinsulinaemic clamp. In another experiment, the influence of glucagon was investigated in seven healthy subjects, who were studied twice during a pancreatic islet clamp with either supplementation of insulin and glucagon, or of insulin alone. In both situations the measurements were performed during euglycaemia. Splanchnic oxygen consumption and net substrate balances were studied by the arterio‐hepatic venous catheterisation technique and measurement of splanchnic blood flow in all experiments. Results: During the euglycaemic hyperinsulinaemic clamp, the splanchnic blood flow increased significantly and the splanchnic oxygen consumption decreased by about 20%, while the net splanchnic glucose output reversed to a net uptake. In the pancreatic islet clamp experiments there was a significant difference between the net splanchnic glucose outputs whether glucagon and insulin or only insulin was supplemented. In spite of this, the splanchnic oxygen consumption decreased by about 20% in both situations, i.e. independent of glucagon supplementation. In both experiments there was a pronounced inhibition of lipolysis, which led to decreased fatty acids availability to the liver. This resulted in a concomitant decrease in hepatic ketone body formation. This decrease could account for about 30% of the decrease in splanchnic oxygen consumption. Conclusion: The reduction in splanchnic oxygen consumption can be explained by decreased ketogenesis, decreased protein synthesis and changes in splanchnic fuel selection, while changes in the rate of gluconeogenesis does not seem to play a significant role.
Changes in dendritic cell migration and activation during SIV infection suggest a role in initial viral spread and eventual immunosuppression
Authors: Barratt‐Boyes S.M. , Zimmer M.I. , Harshyne L.
Published: March 2003

Abstract: Dendritic cells (DC) serve an essential function in linking the innate and acquired immune responses to antigen. Peripheral DC acquire antigen and migrate to draining lymph nodes, where they localize to the T cell‐rich paracortex and function as potent antigen presenting cells. We examined the effects of human immunodeficiency virus (HIV) infection on DC function in vivo using the rhesus macaque/simian immunodeficiency virus (SIV) model. Our data show that during acute SIV infection, Langerhans cell density is reduced in skin and activated DC are increased in proportion in lymph nodes, whereas during AIDS, DC migration from skin and activation within lymph nodes are suppressed. These findings suggest that changes in DC function at different times during the course of infection may serve to promote virus dissemination and persistence: early during infection, DC mobilization may facilitate virus spread to susceptible lymph node T cell populations, whereas depressed DC function during advanced infection could promote generalized immunosuppression.
Influence of microstructure on the mechanical properties and stress corrosion susceptibility of 7050 Al‐alloy
Authors: Yang Ji‐Gang , Ou Bin‐Lung
Published: March 2003

The influence of matrix and grain boundary microstructural characteristics on the mechanical properties and resistance to stress corrosion cracking (SCC) of the 7050 aluminum alloy was investigated. The proposed step‐quench and aging (SQA) treatment can effectively improve the SCC resistance and attain optimum strength by controlling the microstructures, i.e., the coarse and widely‐spaced grain boundary precipitates (GBPs), and a matrix of GP zones with η′ phases. The highest strength of the 7050 alloy is obtained by using duplex aging at 120°C for 6 h and then 168°C for 3 h in the T6 temper. When the duplex aging is used in the SQA treatment, not only the SCC resistance and yield strength are significantly improved, but also the aging time is much reduced simultaneously, as compared to those obtained by the conventional T73 treatment. The process has good potential to be applied in industry. However, the SQA treatment is not applicable to the 7075 alloy because of its high quench sensitivity.
Measuring velocity in high‐temperature liquid metals: a review
Authors: Argyropoulos Stavros A.
Published: March 2003

All fluid mechanics problems in metals‐processing operations are associated with the measurement of fluid velocity. The development of various models of predicting fluid flow characteristics in complex engineering problems has increased the need for fluid velocity measurements. These measurements provide the necessary validation and tuning for model predictions. In addition, measurement of fluid velocity can be used as a tool for process control purposes. Moreover, the continuous push of metal industries for improved quality and efficiency in liquid metal processing operations, has further highlighted the need for liquid metal velocity measurements. This review presents the various techniques used so far to measure velocity in liquid metals. It outlines the advantages and disadvantages of each technique and provides the reader with information for critical analysis.
Donor–acceptor interaction and mutual solubility of the Cu and Sb components in the Ge–Cu–Sb ternary system
Authors: Glasov V. M. , Potemkin A. Ya.
Published: March 2003

The limiting solubilities of copper and antimony in germanium at 773 and 873 K were determined by measuring microchardness of solid solution crystals. The solubility of copper was found to increase substantially in the presence of antimony. This observation was explained based on concept of donor ‐ acceptor interactions resulting in the formation of the (CuSb) charges complex. An analytic expression for the solubility of donors (antimony) as a function of the content of acceptors (copper) and vice versa was obtained. These relations were used to calculate the cosolubility of doping elements in the Ge–Cu–Sb system. The calculated and experimental solubility values were in close agreement with each other.
Thermodynamic study and synthesis of γ‐aluminum oxynitride
Authors: Wang Xidong , Li Wenchao , Seetharaman Seshadri
Published: March 2003

This paper presents the results of the investigation of the thermodynamic properties of γ‐aluminum oxynitride (AlON). The phase relations and thermodynamic properties of AlON were analyzed and the Gibbs energies of AlON with different compositions and temperatures were calculated by a thermodynamic quasi‐parabola rule. Potential phase diagrams of Al‐O‐N system at different conditions have also been calculated. The synthesis conditions of AlON have been determined. AlON was synthesized by sintering the starting materials at 25 MPa in N2 flow at 2073 K for 3 h. Crystal characteristics and microstructures of AlON were determined.
Fish‐mediated indirect effects in a littoral food web
Authors: Lövgren Johan , Persson Lennart
Published: March 2003

The strength of the direct effect by scraping cladocerans and the indirect effect of nutrient regeneration by filtering herbivorous cladocerans on periphyton growth was investigated in a littoral food web. Ten enclosures were erected in a lake in an area with artificial vegetation. Five enclosures were stocked with juvenile perch (Percafluviatilis) and five lacked fish. In addition, a reference area in the artificial vegetation was sampled. The mesh size of the net surrounding the cages was chosen to allow an inflow of phytoplankton into the cages from the surrounding water. The periphyton and filtering herbivorous cladoceran biomasses were highest in the fish‐free treatment. There was no difference in phytoplankton biomass between treatments despite the large difference in filtering herbivorous cladoceran biomass, suggesting that the inflow of phytoplankton into enclosures completely compensated for the loss due to filtering. The reference area and the enclosure with fish showed the same patterns in developments with respect to filtering herbivorous cladocerans and periphyton. Scraping cladoceran biomass was higher in the fish‐free treatment resulting in a positive correlation between scraping cladoceran and periphyton biomass. Our results suggest that the positive indirect effect of filtering herbivorous cladoceran nutrient regeneration on periphyton was stronger than the negative direct effect of grazing by scraping cladocerans on periphyton in this semi‐open system, and that pelagic production by phytoplankton may foster periphyton growth in the littoral habitat via filtering herbivorous cladocerans. Furthermore, heterogeneity within trophic levels involving primary producers of different growth forms such as phytoplankton and periphyton may enhance the potential for compensatory responses via nutrient recycling.
Social trajectories and the evolution of social behavior
Authors: Cahan S. Helms , Blumstein D. T. , Sundström L. , Liebig J. , Griffin A.
Published: March 2003

Current research on the evolution of sociality seeks to integrate a wealth of species‐specific studies to draw more generalized conclusions. Developing a unified theory of social evolution has been a challenging process, hampered by the inherent complexity of social systems. By viewing a species’ social structure as the result of a series, or “trajectory”, of decisions individuals make about whether or not to disperse from their natal territory, whether to co‐breed or refrain from breeding, and whether or not to provide alloparental care, we can more easily evaluate whether selective factors influencing each social decision are similar across taxa. At the same time, the social trajectory framework highlights the interrelationships among different social decisions, both throughout the life of an individual and over evolutionary time. There are likely to be multiple unifying themes within sociality research; we hope that the simple framework outlined here will promote exchange between researchers across taxonomic disciplines to begin to identify common principles.