bluuebunny/crossref_metadata_2025 huggingface dataset:
Apoplastic peroxidases and ascorbate are involved in manganese toxicity and tolerance of Vigna unguiculata
Authors: Fecht‐Christoffers Marion M. , Maier Peter , Horst Walter J.
Published: March 2003

Excessive manganese (Mn) supply induced the formation of brown spots on leaves as typical Mn toxicity symptoms in cowpea (Vigna unguiculata L. Walp.) grown in hydroponics. Differences in Mn resistance between cv. TVu 91 (Mn‐sensitive) and cv. TVu 1987 (Mn‐tolerant) expressed in the density of brown spots in older leaves were due to higher Mn tissue tolerance. Apoplastic water‐soluble peroxidase (POD) in the apoplastic washing fluid (AWF) was enhanced by increasing Mn leaf content and generally significantly higher in leaves of cv. TVu 91 than in cv. TVu 1987. Electrophoresis of AWF revealed the presence of several water‐soluble POD isoenzymes. At toxic Mn supply, the activities of these and additional POD isoenzymes increased more in the Mn‐sensitive cultivar. Levels of ascorbic acid in the apoplast and cytoplasm of the Mn‐sensitive cv. TVu 91 decreased with increasing leaf Mn contents, whereas Mn‐tolerant cv. TVu 1987 was not affected. Mn treatment lead to a stimulation of the enzymes of the ascorbic acid regeneration system (monodehydroascorbic acid reductase and glutathione reductase) in both cultivars, but the activation of glutathione reductase was clearly more enhanced in the Mn‐tolerant cultivar TVu 1987. The results provide circumstantial evidence that apoplastic ascorbate and peroxidases are involved in the expression of Mn toxicity and genotypic Mn tolerance.
Root ammonium transport efficiency as a determinant in forest colonization patterns: an hypothesis
Authors: Kronzucker H. J. , Siddiqi M. Y. , Glass A. D. M. , Britto D. T.
Published: March 2003

Ratios of ammonium (NH4+) to nitrate (NO3–) in soils are known to increase during forest succession. Using evidence from several previous studies, we hypothesize that a malfunction in NH4+ transport at the membrane level might limit the persistence of early successional tree species in later seral stages. In those studies, 13N radiotracing was used to determine unidirectional fluxes and pool sizes of NH4+ and NO3– in seedlings of the late‐successional species white spruce (Picea glauca) and in the early successional species Douglas‐fir (Pseudotsuga menziesii var. glauca) and trembling aspen (Populus tremuloides). At high external NH4+, the two early successional species accumulated excessive NH4+ in the root cytosol, and exhibited high‐velocity, low‐efficiency (15% to 22%), membrane fluxes of NH4+. In sharp contrast, white spruce had low cytosolic NH4+ accumulation, and lower‐velocity but much higher‐efficiency (65%), NH4+ fluxes. Because these divergent responses parallel known differences in tolerance and toxicity to NH4+ amongst these species, we propose that they constitute a significant driving force in forest succession, complementing the discrimination against NO3– documented in white spruce (Kronzucker et al. 1997).
Longitudinal leaf gradients of UV‐absorbing screening pigments in barley (Hordeum vulgare)
Authors: Wagner Heiko , Gilbert Matthias , Wilhelm Christian
Published: March 2003

In vivo leaf characteristics were examined to describe longitudinal gradients of UV‐absorbing screening pigments in barley. Chlorophyll fluorescence properties and in vivo absorption spectra (210–750 nm) of leaves were measured from the base to the tip. Barley leaves showed strong longitudinal gradients of chlorophyll, where chlorophyll concentration increased within the first 5–8 cm from the leaf base, and did not significantly change for the remaining part of the leaf. Fluorescence microscopy was used to localize cell wall bound screening pigments different from flavonoids, since flavonoids lack a blue‐green fluorescence emission (Lichtenthaler and Schweiger 1998). Measurements of in vivo chlorophyll fluorescence indicated that the ratio of UV‐absorbing screening pigments per leaf area increases from the leaf base to the tip. These gradients were confirmed by in vivo absorption spectra. It is demonstrated that leaves in the early stage of development are less protected against UV‐radiation than fully developed mature leaf regions. The experiments show that measurements of in vivo chlorophyll fluorescence are ideally suited as a fast non‐invasive tool to estimate the epidermal UV‐transmittance in different leaf sections.
A strategy for managing fungal infections in haematopoietic stem cell transplantation
Authors: Donnelly J.P.
Published: March 2003

As more indications continue to be found for allogeneic haematopoietic transplantation, more patients are at risk for invasive fungal infectious diseases (IFID), particularly candidiasis and aspergillosis. Risk factors for disease are becoming better defined and diagnostic methods have improved considerably. In addition, there is now international agreement that three elements form the basis for defining IFID (host factors, clinical evidence, and mycological results), that imaging is acceptable for diagnosing disease, and that indirect tests such as antigen detection are also adequate mycological proof of cause. There are also more drugs available and still more to come, offering the potential for selective prophylaxis as well as preemptive and specific therapy, as well as for flexible administration. Hence, all the elements are in place for designing and testing an effective and economically sound strategy for dealing with IFID.
Use of cytomegalovirus immune globulin and ganciclovir for the prevention of cytomegalovirus disease in lung transplantation
Authors: Zamora M.R.
Published: March 2003

Cytomegalovirus (CMV) infection and disease continue to be significant causes of morbidity and mortality in lung transplant recipients. The potential benefits of CMV prophylaxis extend beyond prevention of the immediate CMV infection to potentially preventing CMV‐associated complications, including superinfection due to Aspergillus bacteria, and other opportunistic infections, and bronchiolitis obliterans syndrome (BOS). Longer courses of prophylactic intravenous (IV) ganciclovir, sequential IV/oral therapy, addition of intravenous CMV immune globulin (CMV‐IGIV), surveillance tests, and investigation of the role of hypogammaglobulinemia are a few of the strategies and issues being evaluated to improve CMV prophylaxis and, consequently, graft and patient survival.
Famciclovir treatment of hepatitis B infection following liver transplantation: a long‐term, multi‐centre study
Authors: Manns Michael P. , Neuhaus Peter , Atkinson Gillian F. , Griffin Karen E. , Barnass Stella , Vollmar Jens , Yeang Yvonne , Young Clarence L.
Published: March 2003

Abstract: Famciclovir is a novel guanosine nucleoside analogue with activity against herpes viruses and hepatitis B virus (HBV). Several preliminary reports have described efficacy of famciclovir in patients with recurrent hepatitis B after orthotopic liver transplantation (OLT). This report describes the largest study to date of long‐term famciclovir treatment in patients with de novo or recurrent hepatitis B post‐OLT. One hundred thirty patients with detectable serum HBV DNA after OLT received oral famciclovir 500 mg tid on a compassionate‐use basis. Safety analyses included all treated patients; efficacy was assessed in all patients and a subgroup of 73 patients with complete baseline HBV DNA and alanine aminotransferase (ALT) data who had received ≥6 months of treatment. Efficacy parameters included serum levels of HBV DNA, ALT, and anti‐HBe or anti‐HBs seroconversion rates. Of the 70 patients treated for ≥6 months who could be evaluated for response/non‐response to famciclovir, 52 (74%) were responders, defined as patients who experienced a 70% decrease or more in HBV DNA levels from baseline, or who became HBV DNA‐negative, for at least two consecutive visits. In famciclovir responders, HBV DNA levels decreased by a median of 91% after 12 weeks of treatment, 95% after 6 months and >99% after 18 months of treatment. Marked differentiation between responders and non‐responders could be made soon after the onset of treatment. Among anti‐HBe positive patients with evidence of HBV replication, 12/13 were responders. Patients with high baseline ALT levels experienced more rapid suppression of HBV DNA during therapy with famciclovir. Famciclovir therapy was safe and well tolerated; serious adverse events were reported infrequently. Famciclovir treatment may be beneficial in patients with hepatitis B infection post‐OLT.
Comparative analysis of three genetic modifications designed to inhibit human serum‐mediated cytolysis
Authors: Costa Cristina , Zhao Lisa , Decesare Stephanie , Fodor William L.
Published: March 2003

Hyperacute rejection (HAR) remains a critical immunologic hurdle in the development of xenogeneic organs for human transplantation. Strategies that simultaneously eliminate both natural antibody reactivity and complement activation on the xenogeneic cell surface may be the best approach to achieve clinical application of xenogeneic vascularized organ transplantation. We have developed multiple lines of genetically manipulated mice to evaluate the combination of different genetic approaches aimed at inhibiting antibody and complement‐mediated cell lysis. We utilized transgenic mice expressing the human complement inhibitor, CD59, the human 1,2‐fucosyltransferase (H‐transferase, HT) and the α1,3‐galactosyltransferase (α1,3‐GT) knock‐out mouse line (Gal KO). Our data show that expression of hCD59 in combination with HT expression or the null phenotype of α1,3‐GT are equally effective at preventing human serum‐mediated cytolysis. Interestingly, the triple combination affords no additional protective effect. Therefore, coexpression of HT and a complement inhibitor is the most immediate strategy to genetically engineer transgenic pigs to be used as xenogeneic donors.
Tolerance of T‐independent xeno‐antibody responses in the hamster‐to‐rat xenotransplantation model is species‐restricted but not tissue‐specific
Authors: Chong Anita S.‐F. , Ma Lian Li , Yin Dengping , Blinder Leonard , Shen JiKun , Williams James W.
Published: March 2003

Abstract: Control of early acute xenograft rejection xenoreactions in the hamster‐to‐Lewis rat xenotransplantation model with cyclosporinee (CsA) and leflunomide subdues early T‐independent xenoreactivity and uncovers a late immune response that can be controlled by CsA alone. We had attributed this acquired responsiveness to CsA to the induction of tolerance of T‐independent xeno‐antibody responses in the recipient and recently reported that this tolerance is species‐specific. Here we have further characterized the specificity and nature of this tolerant state. Lewis rats transplanted with either hearts, skin, kidney or spleen/pancreas from Golden Syrian hamsters were treated with leflunomide (5–20 mg/kg/day by gavage) for 14–21 days and CsA (20 mg/kg/day by gavage) continuously from the day of transplant. Some Lewis rats received a second graft of hearts or skin from Golden Syrian hamsters (day 21–30 after first transplant), and a third heart graft from Balb/c mice (day 60 after the first transplant). Serum was harvested and the titers of xenoreactive antibodies were quantified by flow cytometry. All grafts were harvested at the end of each experiment and examined by histological and immunohistochemical methods. The combination of CsA and leflunomide was able to completely inhibit the rejection of kidney, spleen and pancreas xenografts in this hamster‐to‐rat xenotransplantation model. In addition, only a transient treatment with leflunomide was necessary, and long‐term graft survival could subsequently be maintained by CsA alone. Histological examination of these grafts at > 80 days post‐transplantation indicated minimal signs of rejection. These immediately vascularized organs induced T‐independent B‐cell tolerance, so that second grafts of hamster hearts and skin could be maintained with CsA alone. Under the same immunosuppressive regimen, only four out of nine Lewis rats exhibited long‐term hamster skin survival, probably reflecting the increased immunogenicity of the skin compared with other vascularized grafts. Nonetheless, all rats that did not reject the hamster skin graft also did not reject the hamster heart while on CsA alone. Finally, we demonstrate that the tolerant state could be maintained for up to 30 days in the absence of xenograft. The vigorous T‐independent antibody response that mediates acute xenograft rejection in the hamster‐to‐rat model can be tolerized by the immunosuppressive regimen of CsA and leflunomide. The lack of organ specificity for the induction of this tolerance suggests that the xeno‐antigens inducing tolerance may be common endothelial cell antigens. Finally, the presence of the xenograft has been previously shown to be critical for the induction of T‐independent B‐cell tolerance, however, the tolerant state is relatively stable and persists after the removal of the xenograft.
Human and non‐human primate anti‐galactosyl response after injection of rat monoclonal antibody bearing galactosyl epitopes
Authors: Dehoux Jean‐paul , De La Parra Bernardo , Latinne Dominique , Bazin Hervé , Squifflet Jean‐paul , Gianello Pierre
Published: March 2003

Abstract: In the case of clinical use of pig‐to‐human xenografting, any exogenous source of α‐galactosyl epitopes will elicit an anti‐galactosyl immune response, which could be deleterious for the xenograft. The presence of Galα(1–3)Gal residues was thus examined by western blotting on various rat monoclonal antibodies (mAb), which are used in clinical trials. In parallel, the anti‐galactosyl humoral response was assessed in the serum of kidney allograft recipients and experimental baboons, which received these mAbs. Galactosyl residues were evidenced on all rat monoclonal antibody tested. The anti‐galactosyl response was weak in kidney allograft recipients receiving a basic immunosuppression (Cyclosporine, Azathioprine, Prednisolone) and iterative injections of rat mAbs. In contrast, untreated or immunosuppressed baboons that received rat mAbs developed a major anti‐galactosyl humoral response. These results suggest that anti‐galactosyl sensitization produced by therapeutic agents will have to be considered in the case of clinical xenotransplantation.
Continued production of xenoimmune antibodies 6–8 years after clinical transplantation of fetal pig islet‐like cell‐clusters
Authors: Lindeborg E. , Kumagai‐Braesch M. , Tibell A. , Möller E.
Published: March 2003

Abstract: We have monitored the humoral immune responses of 10 type I diabetic patients, xenotransplanted with fetal porcine islet‐like cell clusters for up to 8 years after xenotransplantation. We investigated the immunoglobulin subclass distribution as well as specificity differences of xenoreactive antibodies. Hemagglutintion tests, using pig erythrocytes, showed that some patients maintained higher titers of xenoreactive IgM antibodies during the entire follow up period, compared with pretransplant levels. In microcytotoxicity tests all but one patient tested showed higher than pretransplant levels of cytotoxic antibodies against pig peripheral blood mononuclear cells (PBMC) 6–8 years after transplantation. Levels of Galα1,3Gal specific antibodies, were also high. Antibody dependent cellular cytotoxicity (ADCC) activity against a Galα1,3Gal expressing human B cell line was detected in four patients while ADCC reactivity against adult pig islet cells was detected in only two patients, 6–8 years after transplantation. Immune sera collected 30 days and 1 year after transplantation showed positive staining of adult pig islet cells in fluoromicroscopy whereas sera from later time points did not.

Western blot experiments showed that some patients had IgG1 antibodies reactive against epitopes on pig cells other than Galα1,3Gal, while xenoreactive IgM and IgG2 antibodies mainly reacted with Galα1,3Gal‐containing epitopes as shown by absorption experiments.

These results show that patients continue to produce higher than pretransplant levels of IgM and IgG2 xenospecific antibodies against Galα1,3Gal for extended time periods following xenotransplantation. Some patients also produce xenoreactive IgG1 antibodies directed against non‐Galα1,3Gal epitopes.
Host systemic and local nitric oxide levels do not correlate with rejection of pig proislet xenografts in mice
Authors: Simeonovic Charmaine J. , Cordery Damien V. , Van Leeuwen Barbara , Popp Sarah K. , Townsend Michelle J. , Paule Michelle F. , Wilson J. Dennis , Cowden William B.
Published: March 2003

The rejection of pig proislet xenografts in mice is a CD4 T cell‐dependent process in which macrophages play an important role. To assess the potential for activated macrophages to act as effector cells in xenograft destruction, we have examined the relationship between proislet xenograft rejection, two principal markers of macrophage activation, transcription of inducible nitric oxide synthase (iNOS) and production of nitric oxide (NO), and their temporal relationship to intragraft cytokine gene expression. Xenograft rejection in CBA/H mice correlated with early induction of intragraft host iNOS mRNA and marked intragraft production of NO (reactive nitrogen intermediates, RNI). Intragraft mRNA expression for IFN‐γ, IL‐1β and TNF, cytokines associated with macrophage activation, was also found. These findings suggested that activated macrophages could be contributing to xenograft destruction via local NO‐mediated toxicity at the graft site.To test the role of NO in this model: (1) Q‐fever antigen (QFA) was administered to recipient mice in order to induce high systemic RNI levels and (2) in another experiment, pig proislets were transplanted into iNOS−/− mice. Treatment with QFA correlated with prolonged xenograft survival at 7 days post‐transplant. Splenocytes from QFA‐treated, but not control mice at 7 and 22 days post‐transplant, exhibited inhibition of secondary xenogeneic mouse antiporcine mixed lymphocyte reaction (MLR) that was reversed by culture with the NOS inhibitor N‐methylarginine (NMA). Despite continued elevated NO production, xenograft protection was temporary with complete rejection by day 22. Evidence that locally produced NO was not contributing to rejection was seen when pig proislets transplanted into iNOS−/− mice were rejected with normal kinetics; in these animals intragraft NO production was not detected (despite porcine iNOS gene expression). Failure of activated macrophages to achieve indefinite xenograft survival suggests that other factors are also required. Macrophage potential to effect either destructive or protective roles after pig proislet xenotransplantation suggests that such functions may depend on the site and magnitude of macrophage activation. Together these findings clearly demonstrate that high NO levels in the periphery are not damaging to xenogeneic islet tissue, neither host nor donor NO production is essential for islet xenograft rejection and consequently elevated plasma RNI levels do not represent a direct marker for rejection.
Anti‐N‐glycolylneuraminic acid antibodies identified in healthy human serum
Authors: Zhu Alex , Hurst Rosa
Published: March 2003

Abstract: The first and major clinical obstacle in xenotransplantation is antibody‐mediated hyperacute rejection. Although human natural antibodies against Galα1,3Gal (Gal) antigens, which are common on porcine cells and organs, have been identified to play a major role in hyperacute rejection, other natural antibodies against non‐Gal epitopes may be also involved in the process. Here, we present evidence suggesting that the majority of human anti‐non‐Gal antibodies are specific for carbohydrate structures carrying terminally linked N‐glycolylneuraminic acid (NeuGc), a xenoantigen existing in almost all animals except humans. Furthermore, this anti‐NeuGc activity is detectable in 85% of healthy humans, implicating the involvement of NeuGc in hyperacute rejection and the importance of developing strategies for removing NeuGc for clinical xenotransplantation.
Multivalent Galα1,3Gal‐substitution makes recombinant mucin–immunoglobulins efficient absorbers of anti‐pig antibodies
Authors: Liu Jining , Weintraub Andrej , Holgersson Jan
Published: March 2003

Liu J, Weintraub A, Holgersson J. Multivalent Galα1,3Gal‐substitution makes recombinant mucin–immunoglobulins efficient absorbers of anti‐pig antibodies. Xenotransplantation 2003; 10: 149–163. © Blackwell Munksgaard, 2003

Hyperacute organ xenograft rejection can be prevented by removing anti‐pig antibodies by extracorporeal absorption prior to transplantation. A novel recombinant absorber of anti‐pig antibodies was developed by fusing the cDNA encoding the extracellular part of a mucin‐type protein, P‐selectin glycoprotein ligand‐1, with an antibody Fc fragment cDNA, which upon coexpression with the porcine α1,3 galactosyltransferase carried the xenogeneic epitope, Galα1,3Gal (Liu J., Qian Y., Holgersson J., Transplantation 1997, 63, 1673–1682). The biochemical characterization of the mucin/Ig and its absorption efficacy compared with that of porcine thyroglobulin and Galα1,3Gal‐conjugated beads are reported. The carbohydrate portion of the mucin/Ig constituted 43% of its molecular weight and the majority of the Galα1,3Gal epitopes were O‐linked as assessed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and Western blotting following N‐glycosidase F digestion. Gas chromatography–mass spectrometry of reduced and acetylated saccharides released by α‐galactosidase treatment revealed that the fusion protein carried approximately 140 mol of terminal, α‐linked galactose per mole protein. Based on the reduction in pig aortic endothelial cell cytotoxicity, Galα1,3Gal‐substituted mucin/Igs on agarose beads were, on a carbohydrate molar basis, shown to be approximately 20 times more efficient than agarose‐conjugated pig thyroglobulin, and approximately 5000 and 30 000 times more efficient than Galα1,3Gal‐substituted agarose and macroporous glass beads, respectively. Structural features of the mucin backbone and its carbohydrate core saccharide chains determine the structural context, spatial orientation and spacing of Galα1,3Gal epitopes and are likely to explain the superior absorption efficacy of the recombinant mucin‐type chimera.
Sex ratio and age structure of nomadic Tengmalm's owls: a molecular approach
Authors: Hipkiss Tim , Hörnfeldt Birger , Lundmark Åsa , Norbäck Maria , Ellegren Hans
Published: March 2003

Sex ratio and age structure of Tengmalm's owls Aegolius funereus crossing the Gulf of Bothnia between Sweden and Finland were investigated by catching owls on the island of Stora Fjäderägg during autumn 1999. Using a molecular sexing technique, we investigated the assertions of previous studies that only adult female and juvenile Tengmalm's owls undertake nomadic movements. Juveniles were generally more frequent than adults, and the sex ratio of juvenile owls was significantly female‐biased. However, contrary to expectation, adult males as well as females were caught. Additionally, among juveniles, males migrated earlier than females. Thus we infer that adult males as well as females are nomadic to some extent, and that the difference between the sexes in migratory habits is not as clear as previously thought.
Phylogeographic patterns in the great spotted woodpecker Dendrocopos major across Eurasia
Authors: Zink Robert M. , Drovetski Sergei V. , Rohwer Sievert
Published: March 2003

We sequenced parts of three mitochondrial genes in 67 great spotted woodpeckers Dendrocopos major taken from 17 sites across Eurasia and Japan. Two groups, differing by ca. 3% sequence divergence, were determined to have had independent evolutionary histories: samples from the southeast (Sakhalin, Primor'e, Hokkaido), and the rest of Eurasia. The southeastern group corresponds to the subspecies D. m. japonicus, which will likely merit species status upon study of all subspecies; at present it should be considered an evolutionarily significant unit. From the United Kingdom to the Russian North Pacific, no phylogeographic divisions were found, which is likely a result of recent range expansion following retreat of permafrost after the last ice age.
Badge size, paternity assurance behaviours and paternity losses in male house sparrows
Authors: Václav Radovan , Hoi Herbert , Blomqvist Donald
Published: March 2003

Male quality may influence both the outcome of sperm competition and female faithfulness. In male house sparrows Passer domesticus, the size of the black throat patch (badge) signals dominance and perhaps attractiveness. So far, however, no study has reported any significant relationships between badge size, paternity and paternity assurance behaviours in this species. We found that the time mates spent together at the nest was positively correlated with badge size. Furthermore, although paternity losses were influenced by both the time spent at the nest and within‐pair copulation frequency, we found no relationship between copulation rate and badge size. It seems therefore that copulation frequency served as a paternity assurance behaviour, whereas the time mates stayed together at the nest may have reflected male attractiveness. Alternatively, females may have decided to stay with large‐badged males because they were better able to protect them from harassment by strange males. We also found that paternity losses were related to male badge size; average‐badged males cuckolded were more often than males with smaller or larger badges. We suggest that average‐badged males suffered higher paternity losses because they had different time allocation strategies than other males.
An experimental study of the availability of feathers for avian nest building
Authors: Hansell M. , Ruxton G. D.
Published: March 2003

We sought to investigate the extent to which natural feather availability constrains avian nest construction by provisioning a site with feathers. Twenty patches, each of fifty marked feathers, were made available to naturally breeding passerine birds each week for three breeding seasons. The mean feather loss per week was 14.4% and only in one week of the study did it rise above 40%. The proportion of feathers recovered from local nests of ten passerine species that were marked was less than 3%. It was concluded that natural feather availability is high and that species requiring them for nest building can readily find them.
The liver as a crucial organ in the first line of host defense: the roles of Kupffer cells, natural killer (NK) cells and NK1.1 Ag+ T cells in T helper 1 immune responses
Authors: Seki Shuhji , Habu Yoshiko , Kawamura Toshihiko , Takeda Kazuyoshi , Dobashi Hiroshi , Ohkawa Takashi , Hiraide Hoshio
Published: March 2003

Summary: The liver remains a hematopoietic organ after birth and can produce all leukocyte lineages from resident hematopoietic stem cells. Hepatocytes produce acute phase proteins and complement in bacterial infections. Liver Kupffer cells are activated by various bacterial stimuli, including bacterial lipopolysaccharide (LPS) and bacterial superantigens, and produce interleukin (IL)‐12. IL‐12 and other monokines (IL‐18 etc.) produced by Kupffer cells activate liver natural killer (NK) cells and NK1.1 Ag+ T cells to produce interferon‐g and thereby acquire cytotoxicity against tumors and microbe‐infected cells. These liver leukocytes and the T helper 1 immune responses induced by them thus play a crucial role in the first line of defense against bacterial infections and hematogenous tumor metastases. However, if this defense system is inadequately activated, shock associated with multiple organ failure takes place. Activated liver NK1.1 Ag+ T cells and NK cells also cause hepatocyte injury. NK1.1 Ag+ T cells and another T‐cell subset with an intermediate T‐cell receptor, CD122+CD8+ T cells, can develop independently of thymic epithelial cells. Liver NK cells and NK1.1 Ag+ T cells physiologically develop in situ from their precursors, presumably due to bacterial antigens brought from the intestine via the portal vein. NK cells activated by bacterial superantigens or LPS are also probably involved in the vascular endothelial injury in Kawasaki disease.
Protective effects of melatonin in ischemic brain injury
Authors: Cuzzocrea Salvatore , Costantino Giuseppina , Gitto Eloisa , Mazzon Emanuela , Fulia Francesco , Serraino Ivana , Cordaro Santina , Barberi Ignazio , De Sarro Angela , Caputi Achille P.
Published: March 2003

Recent studies have demonstrated that melatonin is a scavenger of oxyradicals and peroxynitrite and an inhibitor of nitric oxide (NO) production. NO, peroxynitrite (formed from NO and superoxide anion), and poly (ADP‐Ribose) synthetase (PARS) have been implicated as mediators of neuronal damage following focal ischemia. In the present study, we have investigated the effects of melatonin treatment in Mongolian gerbils subjected to cerebral ischemia. Treatment of gerbils with melatonin (10 mg kg−1, 30 min before reperfusion and 1, 2, and 6 hr after reperfusion) reduced the formation of post‐ischemic brain edema, evaluated by water content. Melatonin also attenuated the increase in the brain levels malondialdehyde (MDA) and the increase in the hippocampus of myeloperoxidase (MPO) caused by cerebral ischemia. Positive staining for nitrotyrosine was found in the hippocampus of Mongolian gerbils subjected to cerebral ischemia. Hippocampus tissue sections, from Mongolian gerbils subjected to cerebral ischemia, also showed positive staining for PARS. The degrees of staining for nitrotyrosine and for PARS were markedly reduced in tissue sections obtained from animals that received melatonin. Melatonin treatment increased survival and reduced hyperactivity linked to neurodegeneration induced by cerebral ischemia and reperfusion. Histological observations of the pyramidal layer of CA‐1 showed a reduction of neuronal loss in animals that received melatonin. These results show that melatonin improves brain injury induced by transient cerebral ischemia.
Structure–function relationships of complement receptor type 1
Authors: Krych‐Goldberg Malgorzata , Atkinson John P.
Published: March 2003

Human complement receptor type 1 (CR1) is a large, multifunctional glycoprotein which is a member of the regulators of complement activation family. Like other members of this family, it is composed mainly of tandemly arranged modules, each about 60–70 amino acids long, known as complement control protein repeats (CCPs). Each domain folds independently and contains a hydrophobic core wrapped in β sheets. These domains mediate interactions with C3/C4‐derived fragments. CR1 is the most versatile inhibitor of both classical and alternative pathway C3 and C5 convertases due to its decay‐accelerating activity and co‐factor activity for C3b/C4b cleavage. Moreover, CR1 plays a major role in immune complex clearance due to its high affinity for C3b and C4b. CR1 is an excellent model to study structure–function relationships because its functions are mediated by two distinct but highly homologous sites, each composed of three CCPs. CR1 derivatives carrying just one active site were used to define critical sequences/amino acids. This was achieved by testing functional profiles of the proteins carrying a mutated active site produced by substituting peptides/amino acids with their counterparts from the other site. These mutated proteins, of which we analyzed over 100, permitted the fine mapping of the functional sites. CR1 on primate erythrocytes varies in size. In most cases it is smaller and has fewer active sites than does human CR1. This variation was used to determine that increased copy number (3,000 to 20,000 versus 300 for human CR1) compensates for a smaller size. Moreover, studies of primate CR1 led to the finding that subtle differences in the critical areas, as compared to human sites, produce active sites with a broader functional repertoire. These alterations ensure that short CR1 forms possess similar biologic activities to the large CR1 forms. There is much interest in producing therapeutic agents to inhibit unwanted complement activation. Based on these structure–function analyses, smaller and more potent complement inhibitors derived from CR1 can be produced.

This work was supported by National Institutes of Health grant AI41592.
Structure of killer cell immunoglobulin‐like receptors and their recognition of the class I MHC molecules
Authors: Boyington Jeffrey C. , Brooks Andrew G. , Sun Peter D.
Published: March 2003

Summary: The recognition of class I MHC molecules by killer cell immunoglobulin‐like receptors (KIR) constitutes an integral part of immune surveillance by the innate immune system. To understand the molecular basis of this recognition, the structures of several members of this superfamily have been determined. Despite their functional diversity, members of this superfamily share many conserved structural features. A central question is how these receptors recognize their ligands. The recent determination of the crystal structure of KIR2DL2 in complex with HLA‐Cw3 has revealed the molecular mechanisms underpinning this interaction, which ultimately modulates the cytolytic activity of natural killer cells. While the recognition of MHC molecules by KIR is characterized by a number of unique features, some unexpected similarities with T‐cell receptor recognition of MHC molecules are also observed. The detailed interactions between KIR2DL2 and HLA‐Cw3 and their functional implications will be reviewed here.
Control of intestinal inflammation by regulatory T cells
Authors: Singh Baljit , Read Simon , Asseman Chrystelle , Malmström Vivianne , Mottet Christian , Stephens Leigh A. , Stepankova Renata , Tlaskalova Helena , Powrie Fiona
Published: March 2003

Summary: Transfer of CD4+ T cells to immune‐deficient mice in the absence of the CD25+ subset leads to the development of colitis, indicating that regulatory cells capable of controlling a bacteria‐driven inflammatory response are present in normal mice. Cells with this function are present in the thymus as well as in the periphery of germ‐free mice, suggesting they may be reactive with self‐antigen. These cells resemble CD4+CD25+ cells that inhibit organ‐specific autoimmunity, suggesting that a similar subset of regulatory T cells may control responses to self and foreign antigens. Development of colitis is dependent on accumulation of activated CD134L+ dendritic cells (DC) in the mesenteric lymph nodes, which is inhibited by CD4+CD25+ cells, indicating that regulatory T cells may control DC activation in vivo. Whilst inhibition of T‐cell activation in vitro by CD4+CD25+ cells does not involve interleukin‐10 and transforming growth factor‐β, these cytokines are required for the suppression of colitis. It may be that control of responses that activate the innate immune system requires multiple mechanisms of immune suppression. Recently, we identified CD4+CD25+ cells with immune suppressive activity in the thymus and peripheral blood of humans, raising the possibility that dysfunction in this mechanism of immune regulation may be involved in the development of autoimmune and inflammatory diseases.
THIS ARTICLE HAS BEEN RETRACTED  STEALTH matters: a novel paradigm of durable primate allograft tolerance
Authors: Thomas J. M. , Hubbard W. J. , Sooudi S. K. , Thomas F. T.
Published: March 2003

Summary: We review a novel strategy for tolerance induction developed in rhesus macaques and termed STEALTH. We summarize the evolution of the STEALTH model, the results of successful trials in inducing long‐term, stable transplant tolerance in rhesus kidney and diabetic islet recipients and discuss information related to the mechanism by which durable tolerance is induced. STEALTH tolerance is induced by a 3‐day treatment course of CD3ε immunotoxin (IT) combined with a 14‐day treatment with deoxyspergualin (DSG). IT causes profound depletion of sessile lymph node T cells as well as the more accessible circulating T cells. DSG, an inhibitor of HSC 70‐mediated NF‐κB nuclear translocation, arrests maturation of myeloid dendritic cells, blocks production of proinflammatory cytokines induced by IT administration, and promotes systemic production of Th2 type cytokines that persist indefinitely. Such Th2 cytokine deviation has not been reported in NHP transplant recipients. These studies provide proof of principle in a preclinical model that prevention of both acute and chronic allograft rejection, for at least 2.2–4.9 years of follow‐up, can be achieved in NHP in the absence of chronic immunosuppressive drugs or other interventions. This strategy for inducing NHP tolerance is discussed in relation to current tolerance paradigms.
Comparative genomic analysis of the MHC: the evolution of class I duplication blocks, diversity and complexity from shark to man
Authors: Kulski Jerzy K. , Shiina Takashi , Anzai Tatsuya , Kohara Sakae , Inoko Hidetoshi
Published: March 2003

Summary: The major histocompatibility complex (MHC) genomic region is composed of a group of linked genes involved functionally with the adaptive and innate immune systems. The class I and class II genes are intrinsic features of the MHC and have been found in all the jawed vertebrates studied so far. The MHC genomic regions of the human and the chicken (B locus) have been fully sequenced and mapped, and the mouse MHC sequence is almost finished. Information on the MHC genomic structures (size, complexity, genic and intergenic composition and organization, gene order and number) of other vertebrates is largely limited or nonexistent. Therefore, we are mapping, sequencing and analyzing the MHC genomic regions of different human haplotypes and at least eight nonhuman species. Here, we review our progress with these sequences and compare the human MHC structure with that of the nonhuman primates (chimpanzee and rhesus macaque), other mammals (pigs, mice and rats) and nonmammalian vertebrates such as birds (chicken and quail), bony fish (medaka, pufferfish and zebrafish) and cartilaginous fish (nurse shark). This comparison reveals a complex MHC structure for mammals and a relatively simpler design for nonmammalian animals with a hypothetical prototypic structure for the shark. In the mammalian MHC, there are two to five different class I duplication blocks embedded within a framework of conserved nonclass I and/or nonclass II genes. With a few exceptions, the class I framework genes are absent from the MHC of birds, bony fish and sharks. Comparative genomics of the MHC reveal a highly plastic region with major structural differences between the mammalian and nonmammalian vertebrates. Additional genomic data are needed on animals of the reptilia, crocodilia and marsupial classes to find the origins of the class I framework genes and examples of structures that may be intermediate between the simple and complex MHC organizations of birds and mammals, respectively.
Kinetic perspectives of T cell antigen receptor signaling
Authors: Iwashima Makio
Published: March 2003

T‐cell activation consists of multiple layers of signaling events. Interleukin‐2 production is of interest for many, since its expression determines a critical difference between partial and full T‐cell activation. To achieve full activation of T cells, it is necessary for the T‐cell antigen receptor (TCR) to be engaged for an extended period of time. However, why extended stimulation is required for full T‐cell activation is not understood at the molecular level. In this review, orchestrated events of TCR signal transduction will be analyzed in a kinetic manner and connected toward the understanding of the mechanism of T‐cell activation. Based on recent results, a model of the mechanism that dictates the threshold between partial and full T‐cell activation is proposed.
Genomic variations in precore and cytotoxic T lymphocyte regions in chronic hepatitis B in relationship to interferon responsiveness
Authors: Shindo Michiko , Okuno Tadao
Published: March 2003

Abstract: Aims: Treatment of chronic hepatitis B patients with interferon (IFN) alpha results in a sustained loss of viral replication in as many as 20–40% of cases. The resistance to antiviral treatment by some viruses is due to positive selection of variants harboring mutations that confer resistance. An HBV variant with a stop codon in the precore region (A1896 HBV) has been reported to be associated with the response to IFN therapy. Recently variations in amino acid residues 21 and 27 of the core protein that serve as either partial agonists or antagonists to cytotoxic T‐lymphocyte (CTL) function have been demonstrated to affect response to IFN therapy. In this study, we investigated whether these genomic variations in precore and CTL regions can affect response to IFN therapy. Patients: Twenty‐three patients with chronic hepatitis B were treated with IFN alpha. Of these 23 patients, 6 were responders (defined as showing seroconversion to anti‐HBe, loss of serum HBV DNA and normalization of serum aminotransferase levels), and the remaining 17 were non‐responders. Method: A total of 75 serum samples (3 serial samples per patient collected before, at the end of therapy, and 6 months after therapy) were tested for core promoter and precore wildtype and mutant viral levels and for sequence in the CTL region. Results: There were no significant differences in precore wildtype and mutant viral levels before therapy between responders and non‐responders, and both viral levels significantly decreased equally when measured at the end of therapy. Approximately 90% of non‐responders with HLA‐A2 had no amino acid substitutions in the CTL region before therapy. IFN therapy did not induce any specific mutations in this region. Conclusion: These findings suggest that the precore wildtype and mutant had similar sensitivity to IFN, and that genomic variation in the CTL region does not appear to be associated with response to IFN therapy.
Hepatitis G virus coinfection influences the liver histology of patients with chronic hepatitis C
Authors: Moriyama Mitsuhiko , Matsumura Hiroshi , Shimizu Toshihiro , Shioda Atsuo , Kaneko Miki , Saito Hiroshi , Miyazawa Kouji , Tanaka Naohide , Sugitani Masahiko , Komiyama Kazuo , Arakawa Yasuyuki
Published: March 2003

Abstract: Aims/Background: The present investigation compared the histological features of the liver of chronic hepatitis C patients who are or are not coinfected with hepatitis G virus (HGV) to determine the histological and clinical characteristics of HGV infection. Subjects and Methods: This study included 194 patients with chronic hepatitis C who visited our institution between 1993 and 1995. Detection of serum HGV RNA was performed by nested reverse transcription‐polymerase chain reaction. Scores were assigned to indicate the severity of each of the following features on the liver biopsy of a patient: inflammatory cell infiltration in the periportal, parenchymal, and portal area; fibrous stage; lymphoid aggregates in the portal area; portal sclerotic change; perivenular fibrosis; pericellular fibrosis; bile duct damage; bridging necrosis; and irregular regeneration of hepatocytes (IR). Results: HGV RNA was detected in the sera of 18 (9.3%) of the 194 patients. The histological features of the HGV RNA‐positive patients show significantly more severe bile duct damage, perivenular fibrosis, pericellular fibrosis and IR than the liver of the HGV RNA‐negative patients. The biochemical results in the two groups did not significantly differ. Conclusion: Our data suggest that chronic HGV coinfection worsens the histological features of liver disease.
Lipopolysaccharide‐induced cytokine and receptor expression and neutrophil infiltration in the liver of osteopetrosis (op/op) mutant mice
Authors: Jiang Shuying , Naito Makoto , Kaizu Chikako , Kuwata Kazuhisa , Hasegawa Go , Mukaida Naofumi , Shultz Leonard D.
Published: March 2003

Abstract: Background/Aims: Mice homozygous for the osteopetrosis (op) mutation are genetically deficient in macrophage colony‐stimulating factor (M‐CSF/CSF‐1) and are characterized by defective differentiation and function of macrophages. The aim of this study is to assess the contribution of M‐CSF to lipopolysaccharide (LPS)‐induced cytokine expression and neutrophil infiltration in the liver. Methods: We investigated the effects of LPS administration in M‐CSF‐deficient op/op mutant mice. The expression of cytokines and receptors in the liver was studied by immunohistochemistry and RT‐PCR. Neutrophil infiltration in the liver was also examined. Results: After LPS administration, cytokine production and expression of LPS receptors, such as CD14 and scavenger receptor class A (MSR‐A), were induced at lower levels in op/op mice than those in littermate mice. Neutrophil infiltration in the liver of op/op mice did not differ significantly from that of littermate mice. Anti‐IL‐8 receptor homologue and anti‐C5a receptor antibody reduced the number of infiltrating neutrophils. Conclusions: These findings indicate that deficient macrophage activation following LPS injection in op/op mice is associated with decreased expression of CD14 and MSR‐A in the liver. Thus, M‐CSF plays a critical role in LPS‐induced macrophage activation but does not exert a dominant role in neutrophil infiltration in the liver.
Heterozygosity for the hemochromatosis gene in liver diseases – prevalence and effects on liver histology
Authors: Höhler Thomas , Leininger Sonja , Köhler Heinz H. , Schirmacher Peter , Galle Peter R.
Published: March 2003

Abstract: Background/Aims: The effect of heterozygosity for the C282Y mutation in the HFE hemochromatosis gene on iron accumulation and disease progression in liver disease patients is unclear. Methods: We investigated the prevalence of this mutation in 531 patients and 205 healthy controls. In addition, we assessed the influence of the mutation on liver histology in 34 C282Y heterozygous and 124 age‐, sex‐ and disease‐matched controls without the mutation using the modified HAI and Chevallier score. Results: The highest prevalence of the C282Y mutation was observed in patients with autoimmune hepatitis (17.2%, p<0.01) compared to 6.4% in healthy controls. Heterozygotes with hepatitis C and B virus infection showed higher ferritin and hepatic iron concentrations than patients without the mutation. However, we did not detect significant differences in necroinflammatory or fibrosis scores between carriers of the mutation and controls. Conclusions: There are marked differences in the prevalence of the C282Y mutation in patients with different liver diseases, with the highest prevalence rates in autoimmune hepatitis and PBC. However, the C282Y mutation alone only leads to a mild increase in iron accumulation in the majority of the patients, with the exception of H63D/C282Y compound heterozygotes. We found no evidence for more pronounced fibrosis in C282Y heterozygotes.