bluuebunny/crossref_metadata_2025 huggingface dataset:
The expression of early light‐inducible proteins (ELIPs) under high‐light stress as defense marker in Northern‐ and Southern European cultivars of barley (Hordeum vulgare)
Authors: Bei‐Paraskevopoulou Thalia , Kloppstech Klaus
Published: March 2003

Clones coding for the two small early light‐inducible proteins (ELIP)‐gene families of 13.5 and 17 kDa have been used as markers to study the effect of high‐light intensities on gene expression in cultivars of barley which were bred for growth in Southern and Northern Europe. The mRNA levels of the light‐harvesting chlorophyll a/b protein (LHC‐II) and the small subunit of ribulose‐1,5‐bisphosphate carboxylase (SSU) were determined in addition. These data were correlated to the decay of PSII activity during high‐light stress and its recovery. In all cultivars, the induction of ELIP mRNAs by high light was accompanied by a correspondent reduction of the LHC‐II mRNA level. Furthermore, the LHC‐II mRNA levels observed under low‐light conditions used for the growth of the plants, were in all cases found to be inversely related to the amount of the ELIP which could be induced by a high‐light treatment. In contrast, the amount of the SSU mRNA was reduced only at the highest investigated light intensity of 2 000 μmol m−2 s−1. During recovery from light‐stress, the activity of PSII was quickly restored in all European cultivars. Of these cultivars, however, the cv. Otis which expressed the highest ELIP levels recovered considerably faster than the cultivar p4266N which accumulated the lowest amounts of ELIP under high light. Thus, it appears likely that ELIPs contribute to the restoration of PSII activity during and after photoinhibition.
New results about structure, function and regulation of the chloroplast ATP synthase (CF0CF1)
Authors: Groth Georg , Strotmann Heinrich
Published: March 2003

The chloroplast ATP synthase utilises the energy of a transmembrane electrochemical proton gradient to drive the synthesis of ATP from ADP and phosphate. This multi‐subunit thylakoid membrane‐bound enzyme consists of a proton channel, CF0, and an extrinsic catalytic sector, CF1. Stimulated by the elucidation of a three‐dimensional partial structure of the mitochondrial enzyme, substantial progress has been made to understand the catalytic mechanism and interesting hypotheses have been proposed about the molecular mechanism of energy coupling. The review discusses the present state of knowledge concerning the structure, molecular genetics, catalytic mechanism, energy coupling and regulation of this important enzyme involved in photophosphorylation.
Purification and characterization of pumpkin long‐chain acyl‐CoA oxidase
Authors: De Bellis Luigi , Giuntini Pietro , Hayashi Hiroshi , Hayashi Makoto , Nishimura Mikio
Published: March 2003

Pumpkin (Cucurbita sp.) long‐chain acyl‐CoA oxidase (ACOX) (EC 1.3.3.6) was purified to homogeneity by hydrophobic interaction, hydroxyapatite, affinity, and anion exchange chromatographies. The purified isoenzyme is a dimeric protein, consisting of two apparently identical 72‐kDa subunits. The protein is exclusively localized in glyoxysomes. The enzyme catalyzes selectively the oxidation of CoA esters of fatty acids with 12–18 C atoms and exhibits highest activity with C‐14 fatty acids, but no activity with isobutyryl‐CoA and isovaleryl‐CoA (branched chain) or glutaryl‐CoA (dicarboxylic). The enzyme is strongly inhibited by high concentrations of palmitoyl‐CoA and weakly inhibited by high concentration of myristoyl‐CoA. It is also inhibited by Triton X‐100 at concentrations above 0.018% (w/v) the critical micellar concentration. The consequences of the substrate inhibition for the evaluation of long‐chain ACOX activity in plant tissues are discussed.
Intercellular proteins and β‐1,3‐glucanase activity associated with leaf rust resistance in wheat
Authors: Anguelova Vesselina S. , Van Der Westhuizen Amie J. , Pretorius Zacharias A.
Published: March 2003

To investigate biochemical aspects of resistance conferred by the Lr35 gene for adult‐plant resistance in wheat (Triticum aestivum L.) to leaf rust, pathogen development was related to intercellular protein composition and β‐1,3‐glucanase (EC 3.2.1.39) activities at three growth stages in infected and uninfected resistant (RL6082 [Thatcher/Lr35]) and susceptible (Thatcher) plants. Leaf rust symptoms produced by pathotype UVPrt9 of Puccinia recondita f. sp. tritici showed that resistance conferred by Lr35 was most effective at the flag leaf stage. Furthermore, fluorescence microscopy indicated that resistance was strongly associated with hypersensitive cell death of invaded tissue. According to polypeptide profiles, intercellular proteins with molecular masses of 35, 33, 31 and 26 kDa were constitutively present at higher levels in resistant than in susceptible plants at the flag leaf stage. Four intercellular proteins (35, 33, 32 and 31 kDa) serologically related to β‐1,3‐glucanase were present in resistant and susceptible genotypes during all stages of plant growth. Resistance was associated with high constitutive levels of β‐1,3‐glucanase activity. Susceptibility on the other hand was associated with low constitutive levels of β‐1,3‐glucanase, while high levels were induced by infection during more advanced stages of colonization. Our results suggest that β‐1,3‐glucanase is involved in the defense response controlled by the Lr35 gene.
Characterization of circadian‐regulated mRNAs encoding glycine‐rich RNA‐binding proteins in Pelargonium×hortorum
Authors: Clark David G. , Richards Christina , Brown Kathleen M.
Published: March 2003

Two cDNAs, PhGRP1 and PhGRP2, with high sequence identity to genes encoding glycine‐rich RNA‐binding proteins, have been cloned from Pelargonium×hortorum. PhGRP is represented in the P.×hortorum genome by a single copy. DNA sequence analysis of two independently isolated cDNAs, PhGRP1 and PhGRP2, indicates that PhGRP2 represents a partially spliced version of PhGRP1. The additional intron‐like sequence in PhGRP2 contains a termination codon, which would result in translation of a truncated protein. Expression of PhGRP1 was high in petals, pistils, roots and stems, and lower in leaves. PhGRP2 transcripts were less abundant than those of PhGRP1 in all tissues, but were proportionately higher in flower tissues than in roots and stems, and were not detectable in leaves. PhGRP transcripts were highest in stigma and style tissues, but were unaffected by exogenous ethylene treatment or pollination. PhGRP transcript levels fluctuated in a circadian rhythm with maximal accumulation late in the day.
Calcium deficiency in potato (Solanum tuberosum ssp. tuberosum) leaves and its effects on the pectic composition of the apoplastic fluid
Authors: Seling Simone , Wissemeier Alexander H. , Cambier Pierre , Van Cutsem Pierre
Published: March 2003

Potato plants (Solanum tuberosum ssp. tuberosum cv. Adelheid), multiplied in vitro, were cultivated in growth chambers on nutrient solution at calcium regimes of 1000, 90, 60 or 30 μM Ca. An absolute Ca deficiency, particularly at the low Ca‐supply levels of 30 and 60 μM Ca, manifested itself initially in the form of marginal necrosis in younger, but not in the youngest, leaves of the potato plants. Further symptoms were rolling of the leaf lamina, browning of veins and roots, and finally necrosis also of the youngest leaves. Only in an advanced stage of Ca deficiency, the meristem of the shoots died. Ca‐deficiency symptoms could be expected at a Ca content in the leaves of less than 5 mg Ca (g dry weight)−1. However, there was no close negative correlation between the extent of leaf damage and the total Ca content of the leaves. In order to obtain information about the Ca concentration in the apoplast fluid of the leaves, apoplastic washing fluid was extracted by an infiltration‐centrifugation technique. A low Ca supply reduced the Ca concentration both in the apoplast fluid of the leaves and in the cell walls. Up to 60% more diffusible pectin fragments were then found in the apoplast of younger leaves, as compared to the control supplied with an optimum Ca level of 1000 μM. The amount of diffusible pectins accounted for 1–2% of the total pectin content of younger potato leaves. The size of the existing pectin fragments varied depending on the Ca supply. Compared with an optimum Ca supply of 1000 μM, fewer monomers and up to 7 times more diffusible pectin fragments with a degree of polymerization 9–20 were present at the low Ca‐supply level (30 μM). In addition, polygalacturonase activity in tissue homogenates increased remarkably with Ca deficiency. Thus it appears that one major effect of Ca deficiency was a stimulation of the activity of polygalacturonase, which could control the breakdown of pectic polysaccharides in the cell wall. Whether the release of potentially biologically active pectic fragments in cell walls might be involved in the occurrence of Ca‐deficiency symptoms is discussed.
Screening for Arabidopsis mutants affected in the Nii gene expression using the Gus reporter gene
Authors: Leydecker Marie‐Thérèse , Camus Isabelle , Daniel‐Vedele Françoise , Truong Hoai‐Nam
Published: March 2003

A mutant screen was developed to isolate Arabidopsis thaliana mutants affected in the regulation of the nitrate assimilation pathway. A fusion between the tobacco Nii1 gene (that encodes a foliar nitrite reductase involved in nitrate assimilation) and the Gus reporter gene was introduced into A. thaliana, and shown to be properly regulated by nitrate. Moreover, β‐glucuronidase (GUS) activity in the transgenic plants was essentially detected in the cotyledons and leaves, showing that the organ‐specific expression of the tobacco Nii1 gene was retained in Arabidopsis. M2 plantlets derived from mutagenized seeds homozygous for the Nii‐Gus fusion were screened by histochemical staining of whole plates for GUS activity after growth on nitrate or glutamine. About 250 progenies were screened, leading to the isolation of plants showing an enhanced or reduced staining compared to the control non‐mutagenized plants. Several mutants were analyzed for the transmission of the phenotype to the M3 generation, as well as for levels of GUS or nitrite reductase activities or mRNA levels. A major problem encountered during the screening was the high background of false positives that reproducibly showed altered GUS histochemical staining compared to control plants and did not, however, display any changes in GUS activity levels. One interesting family of mutants was isolated that overexpressed GUS activity and Nii mRNA in the absence of nitrate. These mutants turned out to be cnx mutants impaired in the molybdenum cofactor biosynthesis that is necessary for nitrate reductase activity. These results may indicate that active nitrate reductase is necessary for a correct regulation of nitrate assimilation genes by nitrate.
The peroxisomal glycolate oxidase gene is differentially expressed in yellow and white sectors of the DP1 variegated tobacco mutant
Authors: Barak Simon , Heimer Yair , Nejidat Ali , Volokita Micha
Published: March 2003

The DP1 variegated mutant of Nicotiana tabacum contains translationally defective plastids in its white (W) leaf sectors. In the present study a second type of pigment‐deficient sector displaying a pale‐yellow color (Y sectors) was discerned. Chlorophyll and carotenoids contents in both leaf sectors are very low, although the Y sectors contain twice the carotenoid content of the W sectors. Rubisco large subunit polypeptide content is low in the W sectors, while in the Y sectors its content is comparable to that in the green sectors. However, both leaf sector types do not show photosynthetic activity under ambient CO2 concentration. The W and Y sectors exhibit 40 and 50% reduction in the level of the mRNA encoding the peroxisomal glycolate oxidase (GLO) enzyme, respectively. However, in the W sectors GLO activity and protein levels reached only 30% of that in the green sectors while in the Y sectors they almost reached the green sectors levels. It is suggested that the reduction in GLO mRNA levels in the Y and W sectors is resulted from inhibition of the putative plastid to nucleus signal. Post‐transcriptional mechanism(s) that also regulate GLO gene expression may explain the discrepancies between GLO mRNA and GLO protein levels, as observed between the W, Y and green leaf sectors of the DP1 mutant.
The AHAS gene of Cichorium intybus is expressed in fast growing and inflorescential organs
Authors: Degrande Delphine , Dewaele Eric , Rambour Serge
Published: March 2003

Expression of acetohydroxy acid synthase (AHAS, EC 4.1.3.18) was analysed in biennial chicory (Cichorium intybus L. cv. Witloof) by northern blot analysis and enzyme assays. Young plantlets displayed high enzyme activity and AHAS mRNA accumulation in the root and the young leaves. Conversely, both enzyme activity and AHAS mRNA were undetectable in the mature tuberous taproot produced at the end of the first year. When such a taproot is grown in darkness, it develops an etiolated bud (the chicon) in which enzyme activity and AHAS mRNA are located in the neoformed lateral roots and the youngest central leaves. When this root is grown in the light, it produces a floral stem with many capitules. AHAS activities as well as AHAS mRNA were at the highest in capitules bearing developing seeds. However, AHAS seems strongly expressed in the young and developing tissues which need amino acids for protein synthesis and tightly associated to carbon influx whenever it is provided by photosynthesis or fructan remobilization.
Spatial‐resolved analysis of histological and biochemical alterations induced by water‐soaking in melon fruit
Authors: Du Chatenet C. , Latché A. , Olmos E. , Ranty B. , Charpenteau M. , Ranjeva R. , Pech J. C. , Graziana A.
Published: March 2003

Water‐soaking, a physiological disorder characterised by a glassy texture of the flesh, depreciates greatly the commercial quality of early‐season Charentais cantaloupe melons (Cucumis melo L. cv. Talma). Although it is accepted that the genotype and a number of physiological and environmental factors play a role in the development of the syndrome, the intimate mechanisms responsible for water‐soaking remain unknown. We report here on an integrated study of the development of water‐soaking in fruit. Using nuclear magnetic resonance (NMR) imaging, we have shown that water mobility increased in the diseased tissues. Alteration of the cell wall and the presence of large intercellular spaces were correlated with a severe depletion of cell wall calcium. Water‐soaking developed during the late stages of fruit ripening, but no correlation was found with ethylene biosynthesis. Thus, fruits in which ethylene action was blocked by 1‐methylcyclopropene remained sensitive to water‐soaking. Moreover, the expression of two genes encoding key enzymes in ethylene biosynthesis remained unchanged in response to water‐soaking. The major changes observed concerned a protein implicated in calcium signalling processes. While the amount of total calmodulin, the ubiquitous calcium binding protein, was not modified, a particular calmodulin‐binding protein (CaM‐BP) was absent in water‐soaked but not in sound mature tissues. This CaM‐BP may be a marker or a determinant of this physiological disorder.
Response of senescing cotyledons of clusterbean to water stress in moderate and low light: Possible photoprotective role ofβ‐carotene
Authors: Deo Prativa M. , Biswal Basanti
Published: March 2003

Senescence of clusterbean (Cyamopsis tetragonolobaL.) cotyledons in moderate light (12 W m−2) brings about a loss in the pigments, enhanced lipid peroxidation and a decline in PS II photochemical activity without any loss either in Dl protein or in the level ofβ‐carotene. The senescence syndrome is aggravated in the cotyledons of water‐stressed seedlings with an increase in thylakoid lipid peroxidation, a decline in the level ofβ‐carotene and a quantitative loss in the Dl protein. Loss of the protein, however, is arrested in the seedlings experiencing water stress at low light (3 W m−2) intensity that correlates with the stability in the level ofβ‐carotene and a slow rate of lipid peroxidation. Loss of the protein in moderate light is attributed to water‐stress sensitized photoinhibitory damage. The data on changes in the components of xanthophyll cycle suggest the low activity of the cycle both during senescence and water stress. It is, therefore, concluded thatβ‐carotene may contribute to the assembly and stability of the Dl protein during senescence and water stress in clusterbean cotyledons.
Phosphoenolpyruvate carboxylase in mistletoe leaves: Regulation of gene expression, protein content, and covalent modification
Authors: Li Xuemei , Wanek Wolfgang , Nehls U. , Popp Marianne , Hampp Rüdiger , Rennenberg Heinz , Einig Werner
Published: March 2003

Seasonal changes in the activity of phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31), a key enzyme in the interaction of carbohydrate and nitrogen metabolism, were studied in leaves of the C3 semiparasitic mistletoe, Viscum album, growing on different host trees. Maximum extractable PEPCase activities were higher in leaves of mistletoes growing on Betulapendula and Alnusglutinosa hosts compared with those on the conifers, Abies alba and Larix decidua. Independent of host, maximum extractable PEPCase activities were high in spring and autumn while low in summer. Samples with higher PEPCase activities showed higher amounts of PEPCase protein and higher PEPCase mRNA levels. A curvilinear correlation between leaf total nitrogen content and the maximum extractable PEPCase activity as well as PEPCase mRNA level suggested that nitrogen might affect the activity of PEPCase of mistletoe by up‐regulating gene expression. In addition to extractable activity, seasonal changes of the PEPCase activation state, the ratio of activities resulting from limited:non‐limited assays, were found, which was correlated to the variation of malate content in leaves of mistletoe. ATP‐dependent activation of PEPCase was characterized by an increase in I0.5(l‐malate), indicating that PEPCase of leaves of mistletoes is probably regulated via phosphorylation.
CO2 enrichment and development of freezing tolerance in Norway spruce
Authors: Dalen Lars Sandved , Johnsen Øystein , Ogner Gunnar
Published: March 2003

Plant growth and adaptation to cold and freezing temperatures in a CO2‐enriched atmosphere have received little attention despite their predicted effects on plant distribution and productivity. In this study we looked at the interaction between elevated CO2 and development of freezing tolerance in Norway spruce (Picea abies (L.) Karst.). First‐year seedlings were grown under controlled conditions in an atmosphere enriched in CO2 (70 Pa) for one simulated growth season. We measured shoot growth, registered the timing of growth cessation and bud set, measured needle net photosynthetic rate, and determined needle carbohydrate concentration (fructose+pinitol, glucose, sucrose, inositol, raffinose and starch). Freezing tolerance (LT50) was determined after exposing whole seedlings to temperatures ranging from −6.5 to −36.0°C and scoring for visual needle browning. Elevated CO2 did not affect height growth or the timing of growth cessation and bud set. The only statistically significant effects of CO2 treatment were on seedling dry weight, percent dry matter and starch content. During the three weeks after growth cessation and bud set, freezing tolerance increased from −10 to −35°C, and there was a marked increase in all soluble sugars except inositol. However, neither freezing tolerance nor the concentration of soluble sugars was significantly influenced by elevated CO2.
Effects of Pb‐EDTA and EDTA on oxidative stress reactions and mineral uptake in Phaseolus vulgaris
Authors: Geebelen Wouter , Vangronsveld Jaco , Adriano Domy C. , Van Poucke Lucien C. , Clijsters Herman
Published: March 2003

Sequestration of Pb by synthetic chelates has been reported to increase bioavailability, uptake, and translocation of this metal in plants. In this work the potential phytotoxic effects of Pb‐EDTA were investigated in Phaseolus vulgaris L. cv. Limburgse vroege plants grown on hydroponics. Addition of 50 µM Pb‐EDTA to the nutrient solution caused a significant induction of syringaldazine peroxidase (SPOD; EC 1.11.1.7) in roots and primary leaves and guaiacol peroxidase (GPOD; EC 1.11.1.7) in leaves. Addition of 100 µM Pb‐EDTA further exacerbated ascorbate peroxidase (APOD; EC 1.11.1.11), GPOD, dehydroascorbate reductase (DHAR; EC 1.8.5.1), glutathione reductase (GR; EC 1.6.4.2) and malic enzyme (ME; EC 1.1.1.40) in roots and APOD and ME in primary leaves. Addition of 200 µM Pb‐EDTA also induced DHAR in leaves. This induction of peroxidases (SPOD, GPOD, APOD), enzymes of the ascorbate‐glutathione cycle (DHAR, GR in roots) and of an NADP+ reducing enzyme in roots and primary leaves indicates that oxidative stress has been initiated. At 200 µM Pb‐EDTA, chlorophyll a and b content in leaves was significantly reduced while visible effects on root morphology and shoot length were observed, while no significant morphological effects were found in the leaves, confirming the sensitive character of the measured enzymes as plant stress indicators. Elevation of the Pb‐EDTA concentration in the growth medium significantly reduced the content of Ca, Fe, Mn and Zn taken up by plants, probably due to ion leakage as a result of observed toxicity. Addition of up to 200 µM EDTA increased chelation of divalent cations in nutrient solution resulting in reduced plant uptake of Zn, Cu, Fe and Mn. This did not result in phytotoxicity.
The electrical impedance spectroscopy of Scots pine needles during cold acclimation
Authors: Zhang Gang , Ryyppö Aija , Repo Tapani
Published: March 2003

The electrical impedance spectroscopy (EIS) was applied to current‐year needles of Scots pine (Pinus sylvestris L.) in an 8‐year provenance field trial in central Finland during frost hardening. The EIS analysis of the needles using a Model‐A equivalent circuit indicated a sequence of events in the needles during their cold acclimation. Some of the EIS‐parameters referred to maturation phenomena occurring during the pre‐hardening phase at the end of the growing season, and some parameters displayed a clear coincidence with the frost hardening itself. Significant differences between provenances were found in several of the Model‐A parameters. Extracellular resistance (re) and β‐coefficient decreased in all provenances in the pre‐hardening phase in August and until mid‐September. In the same phase, both the intracellular resistance (ri) and the cell membrane time constant (τm) first increased and then decreased. According to τm, re and β there was a clear gradation between provenances in the pre‐hardening phase. From the end of September significant differences were found in the intracellular resistance between provenances, corresponding with the differences in their hardening pattern. The dry weight (DW) content of needles increased during the study period but no clear differences were found between the provenances.
Expression of defender against apoptotic death (DAD‐1) in Iris and Dianthus petals
Authors: Kop Dianne A.M. van der , Ruys Gerda , Dees Dianka , Van Der Schoot Chris , Douwe de Boer A. , Van Doorn Wouter G.
Published: March 2003

The gene defender against apoptotic death (DAD‐1) prevents programmed cell death in animal cells. We investigated the expression pattern of DAD‐1 in petals of iris (Iris × hollandica cv. Blue Magic) and carnation (Dianthus caryophyllus cv. Etarro). DAD‐1 expression in Iris petals was strongly reduced by the time of visible senescence, which occurs 4 days after flower opening. Microscopic analysis showed that most mesophyll cells had died prior to a clear decrease in DAD‐1 expression and that epidermis cells started to die by that time. In carnation petals DAD‐1 expression also decreased by the time of massive cell death. After ethylene treatment, DAD‐1 expression in carnation again decreased concomitant with the advance in massive cell death. In conclusion, DAD‐1 is not an early regulator of petal cell death. Its expression may be required for the programmed dismantling of cells, as it ceases only just prior to, or concomitant with, cell death.
Preventing opportunistic infections in bone marrow transplant recipients
Authors: Dykewicz C.A.
Published: March 2003

In 1996, a Center for Disease Control and Prevention (CDC)‐sponsored working group began developing guidelines for preventing opportunistic infections (OIs) in bone marrow transplant (BMT) recipients. The purposes of the guidelines are to: a) summarize current data regarding the epidemiology of OIs in BMT recipients; b) produce an evidence‐based statement of recommended strategies for preventing OIs in BMT recipients; c) decrease the incidence, morbidity, and mortality of OIs in BMT recipients; and d) define directions for future OI prevention research. Each recommendation is given two ratings: one indicating the strength of the recommendation, and another indicating the strength of evidence supporting the recommendation. The target audience for the guidelines includes transplant and infectious disease physicians and BMT unit and clinic staff. The BMT OI guidelines include sections on viral, bacterial, fungal, protozoal, and helminth infections, immunization, infection control, and blood and stem cell safety. The disease‐specific sections address preventing exposure and disease among both adult and pediatric recipients of allogeneic and autologous BMTs. The immunization section addresses: a) immunization of BMT recipients, their household contacts, and health care workers; b) travel immunizations for BMT recipients; and c) passive immunization with immune globulin products. The infection control sections address room ventilation, isolation and barrier precautions, and prevention of nosocomial and other infections (e.g. infections acquired from visitors, plants, food, pets, construction sites, etc.). The blood safety section contains recommendations on preventing transmission of infections to BMT recipients from infected donated cells. After the guidelines are made available for public comment, they will be finalized and published in the Morbidity and Mortality Weekly Report and placed on the CDC web site (
Note).
Fluconazole in transplant recipients: options and limitations
Authors: Strahilevitz J. , Sugar A.M. , Engelhard D.
Published: March 2003

Fluconazole is currently a first‐line agent used for therapy of non‐critically ill patients with candidal infection. Its efficacy, the availability of an oral formula, and its relatively low toxicity make it a very attractive drug for use in many clinical situations. The advisability of prophylaxis and empirical treatment in transplant patients is a difficult issue for the following reasons: the potential emergence of resistance to the azoles, the lack of solid data establishing its advantage over placebo and/or oral nonabsorbable antifungal agents in some of the clinical conditions encountered, its ineffectiveness against molds, and its cost. Judicious use of fluconazole where its efficacy has been well established would provide the best therapy for patients and would limit the emergence of potential pathogens. As new antifungal agents are approved for clinical use, appropriate clinical trials will need to be designed and conducted in order for clinicians to make rational decisions in selecting the most appropriate drug for the specific indication. Prophylaxis and treatment with fluconazole in various transplant situations is reviewed.
The use of itraconazole as prophylaxis against invasive fungal infection in blood and marrow transplant recipients
Authors: Boyle B.M. , McCann S.R.
Published: March 2003

Invasive fungal infections play a key role in contributing to morbidity and mortality in patients undergoing treatment for haematological malignancies and related diseases. Risk factors for development of invasive fungal infections after blood or bone marrow transplantation include the use of broad‐spectrum antibiotics, steroids, mismatched or unrelated donor transplant, right atrial catheters, and prolonged or profound neutropenia. Previous attempts at use of oral itraconazole as antifungal prophylaxis in the setting of chemotherapy‐induced neutropenia were unsuccessful because of its poor absorption in capsule form. Itraconazole‐cyclodextrin is well absorbed even in the presence of chemotherapy‐induced neutropenia. Plasma levels of 250–500 ng/ml are required for prophylaxis. Studies to date show a favourable outcome in patients receiving itraconazole as prophylaxis against invasive fungal infections, although many studies looked at small numbers of patients and the incidence of invasive fungal infection in the control groups was low, prohibiting meaningful statistical evaluation. Fungi differ in their sensitivity to antifungal agents, and itraconazole is not the agent of choice in all patients. With the widespread use of antifungal prophylaxis, the possibility of resistance to antifungal agents and an increase in the number of invasive fungal infections caused by ubiquitous fungi previously considered nonpathogenic must be considered as potential problems.
Significant post‐transplant hypogammaglobulinemia in six heart transplant recipients: an emerging clinical phenomenon?
Authors: Corales R. , Chua J. , Mawhorter S. , Young J.B. , Starling R. , Tomford J.W. , McCarthy P. , Braun W.E. , Smedira N. , Hobbs R. , Haas G. , Pelegrin D. , Majercik M. , Hoercher K. , Cook D. , Avery R.K.
Published: March 2003

Background:The recent development of powerful agents such as mycophenolate mofetil and tacrolimus has altered current regimens for the prevention and treatment of allograft rejection. Questions have been raised about these newer regimens in terms of susceptibility to opportunistic infections and effects on host defenses. Severe hypogammaglobulinemia has been infrequently described in solid organ transplant recipients, but has been recently noted in six heart transplant recipients at one center, of whom five were receiving a combination of tacrolimus, mycophenolate mofetil, and prednisone.

Methods:Case summaries of six recent heart transplant recipients with total immunoglobulin G (IgG) levels of less than 310 mg/dl, five of whom had cytomegalovirus (CMV) infection and three of whom had multiple infections includingNocardia, invasiveTrichophyton, andAcinetobacterbacteremia. Previous literature was reviewed with the aid of a Medline search using the search terms hypogammaglobulinemia; kidney, liver, heart, lung, and organ transplantation; mycophenolate mofetil; tacrolimus; cyclosporine; azathioprine; and nocardiosis.

Results:We here report six cardiac transplant recipients seen over a period of one year who were found to have immunoglobulin G levels of 310 mg/dl or below (normal: 717–1400 mg/dl). The first five patients were diagnosed because of evaluation for infections; the sixth, who was asymptomatic with an IgG level of 175, was found during screening for hypogammaglobulinemia instituted as a result of these first five patients. All six patients had received steroid pulses for rejection; all received mycophenolate mofetil; and 5/6 had been switched from cyclosporine to tacrolimus because of steroid‐resistant rejection. Transient neutropenia (absolute neutrophil count less than 1000) was observed in 2/6; 3/6 had received OKT3 therapy for refractory rejection. These six patients were treated with a combination of antimicrobials, immunoglobulin replacement, and decrease in immunosuppressive therapy.

Conclusions:The finding of unexpected hypogammaglobulinemia and concomitant infectious complications in six heart transplant recipients highlights a possible complication in a subset of patients receiving newer immunosuppressive agents. A larger prospective study is underway to determine risk factors for development of post‐transplant hypogammaglobulinemia and to assess pre‐transplant immune status of these recipients. Monitoring of immunoglobulin levels in high‐risk patients receiving intensified immunosuppressive therapy for rejection may help to prevent infectious complications.
Effects of immunosuppression and organ transplantation on the natural history and immunopathogenesis of hepatitis C virus infection
Authors: McCaughan G.W. , Zekry A.
Published: March 2003

The hepatitis C virus (HCV) is recognized as the leading cause for parenterally transmitted hepatitis. It is characterized by a high propensity to chronicity. Several efforts have been directed towards understanding the natural history of chronic HCV infection and the immunopathogenic pathways involved in mediating liver injury in the non‐immunosuppressed and immunosuppressed states. In the non‐immunosuppressed setting, liver damage seems to be largely immune mediated. In contrast, in the non‐immunosuppressed state, there are several other factors that may modify the natural course of the infection and play a role in mediating liver injury. In this review we will address the natural history, virological and immunological aspects of HCV infection. Also, the role played by immunosuppression and organ transplantation in modifying the course of the infection and the pathogenesis of liver injury will be discussed.(Note)
Cytomegalovirus prophylaxis with ganciclovir and cytomegalovirus immune globulin in liver and intestinal transplantation
Authors: Tzakis A.G.
Published: March 2003

Liver and intestinal transplant recipients at the University of Miami receive an intensive regimen of cytomegalovirus (CMV) prophylactic therapy consisting of a combination of CMV immune globulin intravenous (CMV‐IGIV, CytoGam®) and ganciclovir. The 5‐year experience with this regimen in liver transplant patients showed effective CMV prophylaxis in this patient population. The importance of an effective prophylactic strategy was underscored by higher observed rates of chronic rejection and post‐transplant lymphoproliferative disorder (PTLD) in CMV‐infected patients. The use of CMV‐positive donors for intestinal transplants did not increase the incidence of CMV disease. Intestinal transplant recipients had improved survival rates, reflecting an aggressive policy of monitoring, immunosuppression, and CytoGam® plus ganciclovir prophylaxis.
Diagnostic yield of bronchoalveolar lavage following renal transplantation
Authors: Reichenberger F. , Dickenmann M. , Binet I. , Solèr M. , Bolliger C. , Steiger J. , Brunner F. , Thiel G. , Tamm M.
Published: March 2003

Abstract: Organ transplant recipients are at high risk of infectious pulmonary complications. In this retrospective study, the diagnostic yield of bronchoalveolar lavage (BAL) was evaluated in renal transplant recipients. The results were analysed in special regard to the clinical presentation of pulmonary infections and the possible impact of new immunosuppressive agents. Over a 5‐year period 91 BAL were performed in 71 renal transplant recipients. Microorganisms were isolated from 69% of BAL (63/91): bacteria 32%; cytomegalovirus (CMV) 27%; Pneumocystis carinii (PC) 22%; other viruses 9% (HSV; EBV, RSV, adenovirus, HHV8); Aspergillus fumigatus 1%. Total cell counts and neutrophil counts in BAL were significantly elevated in bacterial infection, whereas BAL positive for PC showed eosinophilia (P<0.05). There was no association between clinical symptoms and the radiological pattern of infiltrates and the type of infection. Immunosuppression containing tacrolimus or mycophenolate mofetil was associated with a significantly higher percentage of PC and CMV infections compared to cyclosporin‐based immunosuppression (65% vs. 30%, P<0.005). A considerable number of PC and CMV infections occurred beyond 6 months after transplantation. In conclusion, BAL has a high diagnostic yield in renal transplant recipients. Infection with CMV and PC should also be considered beyond 6 months after transplantation, and prophylaxis for opportunistic infections should be given if the immunosuppression is intensified.
Identifying the patient at risk for post‐transplant lymphoproliferative disorder
Authors: Cockfield S.M.
Published: March 2003

Abstract:Post‐transplant lymphoproliferative disorders (PTLD) are a recognized complication of the immunosuppression required to prevent allograft rejection, occurring in 1–20% of recipients of solid organ transplants. Several factors greatly increase the risk of developing PTLD early post‐transplant in any individual recipient. Epstein–Barr virus (EBV) infection is critical in the pathogenesis of the majority of these cases. Pre‐transplant EBV seronegativity increases the incidence of PTLD 10‐ to 75‐fold over that of EBV‐seropositive recipients. Other risk factors include very young recipient age, cytomegalovirus infection or mismatching (donor positive–recipient negative), aggressive immunosuppression with conventional biologic agents, and the type of organ transplanted. In contrast, the risk of developing PTLD late in the post‐transplant course does not appear to be influenced by the type of immunosuppressive agents employed, but rather by the duration of any immunosuppression. The role of EBV in late PTLD is also less certain, as a greater proportion of lesions are not associated with evidence of EBV infection. As the understanding of these risk factors has expanded, opportunities exist to target those populations at highest risk for the development of PTLD for aggressive monitoring and pre‐emptive or prophylactic therapy. It is hoped that implementation of such strategies will render early PTLD a preventable complication of transplantation.
The role of antiviral and immunoglobulin therapy in the prevention of Epstein–Barr virus infection and post‐transplant lymphoproliferative disease following solid organ transplantation
Authors: Green Michael , Reyes Jorge , Webber Steven , Rowe David
Published: March 2003

Abstract:The recognition of the importance of Epstein–Barr virus (EBV) infection, including EBV‐associated post‐transplant lymphoproliferative disease (PTLD), has led to a new focus on the prevention of this problem. This paper reviews the scientific rationale behind, and clinical experience with, the use of chemoprophylaxis (using acyclovir or ganciclovir) and immunoprophylaxis (using intravenous immunoglobulin) in the prevention of EBV/PTLD. While some centers have already introduced the use of one or both of these agents as standard prophylaxis against the development of this complication, published data in support of these protocols are currently lacking. Well designed clinical trials are necessary to evaluate the potential role of both antiviral and immunoglobulin agents in the prevention of EBV/PTLD in organ transplant recipients.
Aspergillosis in lung transplantation: incidence, risk factors, and prophylactic strategies
Authors: Gordon S.M. , Avery R.K.
Published: March 2003

Abstract:Invasive aspergillosis remains a significant cause of morbidity and mortality in transplantation, especially lung and allogeneic bone marrow transplant recipients. The epidemiology, classic and newly recognized risk factors, and incidence of aspergillosis are reviewed. Risk factors include environmental exposures, airway colonization, profound immunosuppression, neutropenia, prior cytomegalovirus infection, and renal dysfunction. Clinical and radiographic presentations of invasive aspergillosis are discussed, including some unusual manifestations in lung transplant recipients. Early and accurate diagnosis of aspergillosis remains a challenge, and diagnostic strategies are reviewed, with an emphasis on the chest computerized tomography scan and on transbronchial or open lung biopsy. Recent advances include prophylactic and pre‐emptive antifungal strategies, newer therapeutic agents, and improved risk stratification.
Removal of xenoreactive antibodies by protein‐A immunoadsorption: experience in 22 patients
Authors: Ramos Angeles , Ruiz Juan Carlos , . de Francisco A. L. M , Gómez‐Fleitas Manuel , Arias Manuel
Published: March 2003

Abstract: The presence of naturally occurring anti‐Galα1–3Gal (antiαGal) Ab in human serum is believed to be a major factor in the pathogenesis of hyperacute rejection of discordant organ xenografts such as the pig‐to‐human combination. Galα1–3Gal epitopes are expressed on pig tissues and the binding of anti‐Galα1–3Gal leads to endothelial cell activation and complement‐mediated hyperacute graft rejection. Several strategies have been suggested in donor animals or in the xenograft recipient to overcome the anti‐αGal barrier. Protein‐A immunoadsorption (PAIA) was developed for the in vivo removal of circulating Ab and it has been shown to be effective in cases where pathogenic auto or alloAb are present. The aim of our study was to analyze the effect of PAIA on total and xenoreactive serum anti‐αGal immunoglobulin levels in a group of patients treated with this technique for different diseases. After three consecutive sessions of PAIA, total and xenoreactive IgG and IgM immunoglobulin levels were decreased by more than 50% of pre‐treatment levels. So we conclude that PAIA is an effective method to significantly reduce circulating Ab, including xenogeneic IgM and IgG Ab. This mode of therapy might be considered as a tool to overcome hyperacute xenograft rejection. PAIA combined with other therapeutic approaches may well protect the xenograft.
Naturally acquired anti‐αGal antibodies in a murine allograft model similar to delayed xenograft rejection
Authors: Salvaris Evelyn , Gock Hilton , Han Wenruo , Murray‐Segal Lisa , Barlow Helen , Mottram Patricia , Pearse Martin , Cowan Peter , Goodman David , D’Apice Anthony J. F.
Published: March 2003

Abstract: Antibodies directed against galactose‐α1,3‐galactose (αGal) are believed to play an important a role in the pathogenesis of delayed xenograft rejection (DXR). This study was designed to determine whether α1,3‐galactosyltransferase‐deficient (Gal KO) mice can naturally acquire a sufficient anti‐αGal titre to cause the delayed type rejection of αGal‐expressing hearts. Gal KO mice of various ages were assessed for anti‐αGal antibody levels. αGal‐expressing hearts were transplanted heterotopically into these mice and monitored daily. Rejecting and surviving hearts were evaluated histologically. Results: in Gal KO mice greater than 6‐month‐old, 64% had an anti‐αGal antibody titre above the background level. When wild‐type αGal‐expressing hearts were transplanted into this group, 45% of grafts rejected within 5 to 13 days. Histological examination of the rejected hearts displayed marked tissue damage and an inflammatory infiltrate of predominantly macrophage/monocytes. Surviving grafts showed preserved morphology. Like humans, Gal KO mice naturally develop anti‐αGal antibodies with age. The titre in these mice was sufficient to cause a “delayed‐type” rejection of a significant proportion of αGal‐expressing cardiac grafts. This model thus provides an opportunity to investigate the role of naturally acquired anti‐αGal antibodies in the pathogenesis of DXR.
Natural antibodies and the host immune responses to xenografts
Authors: Cramer Donald V.
Published: March 2003

Abstract: Natural antibodies are present in the serum of individuals in the absence of known antigenic stimulation. These antibodies are primarily IgM, polyreactive, and encoded by immunoglobulin V genes in germline configuration. Natural antibodies are produced by B‐1 lymphocytes, cells that form the primary cell of the fetal and newborn B cell repertoire and may represent the basic foundation upon which the adult repertoire of B cell antibodies is based. Natural antibodies react with a variety of endogenous and exogenous antigens, including xenoantigens expressed by tissues between unrelated species. These antibodies are capable of causing the immediate rejection of grafts exchanged across species barriers. One of the central issues related to our understanding of the immunopathologic mechanisms responsible for rejection of xenografts is whether pre‐formed natural antibodies and new antibodies induced following xenotransplantation are produced by the same pathways of B cell antibody production. We have established in studies conducted in rodents and humans that the initial phases of antibody production xenogeneic tissues involves the use of a restricted population of Ig germline genes to encode xenoantibody binding. As the humoral xenoantibody response matures, the same closely‐related groups of Ig V genes are used to encode antibody binding and there is evidence for an isotype switch to IgG antibody production and the appearance of somatic mutations consistent with antigen‐driven affinity maturation. Our findings in both rodent and human studies form the basis for our proposal that the xenograft response reflects the use of B cell natural antibody repertoires originally intended to provide protection against infection. The host humoral response is inadvertently recruited to mount antibody responses against foreign grafts because they display carbohydrate antigens that are shared by common environmental microbes. This model of xenoantibody responses is being tested in our laboratory through the analysis of the binding of xenoantibodies in their original non‐mutated configuration, and the examination of the effect of specific point mutations and gene shuffling have on xenoantibody binding activity. Establishment of the relationships between Ig structural changes and subsequent changes in binding affinity should provide important insights into the role that natural antibodies and the cells that produce them play in the evolution of the host’s humoral responses to xenografts.
Molecular and functional characterization of porcine LFA‐1 using monoclonal antibodies to CD11a and CD18
Authors: Álvarez B. , Doménech N. , Alonso F. , Sánchez C. , Del Moral M. Gómez , Ezquerra A. , Domínguez J.
Published: March 2003

Abstract: We describe in this report the production and characterization of monoclonal antibodies (mAb) to the swine homologues of CD11a and CD18 antigens, and their use for phenotypic and functional analysis of porcine leukocytes. Monoclonal antibodies BL1H8 and BL2F1 precipitated two bands of approximately 170 and 95 kDa, whereas mAb BA3H2 brought down three bands of 170, 155 and 95 kDa, from alveolar macrophage lysates. Clearance of macrophage lysates with mAbs BL1H8 and BL2F1 resulted in complete removal of the 170‐kDa band. The cell distribution of the molecules recognized by these mAbs was similar to that of human LFA‐1. It was found on all leukocytes, although its expression varied among the different leukocyte subpopulations, with monocytes, granulocytes and a subset of CD8+ cells expressing the highest levels. Cross‐blocking studies showed that these antibodies recognize different epitopes on porcine LFA‐1. Both anti‐LFA‐1 mAbs strongly inhibited the mitogenic response of PBMC to ConA, whereas the anti‐CD18 mAb had no effect. These anti‐LFA‐1 mAbs also inhibited the mixed lymphocyte reaction (MLR) and the NK cell‐mediated lysis of K‐562 cells.