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ABSTRACT: Partitioning-defective (par) genes were originally identified as genes that are essential for the asymmetric division of the Caenorhabditis elegans zygote. Studies have since revealed that the gene products are part of an evolutionarily conserved PAR-atypical protein kinase C system involved in cell polarity in various biological contexts. In this study, we analyzed the function of par6 during sea urchin morphogenesis by morpholino-mediated knockdown and by manipulation swapping of the primary mesenchyme cells (PMCs). Loss of Par6 resulted in defects in skeletogenesis and gut differentiation in larvae. Phenotypic analyses of chimeras constructed by PMC swapping showed that Par6 in non-PMCs is required for differentiation of archenteron into functional gut. In contrast, Par6 in both PMCs and ectodermal cells cooperatively regulates skeletogenesis. We suggest that Par6 in PMCs plays an immediate role in the deposition of biomineral in the syncytial cable, whereas Par6 in ectoderm may stabilize skeletal rods via an unknown signal(s).
Archiv für Entwickelungsmechanik der Organismen 08/2012; 222(5):269-78. · 1.77 Impact Factor
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ABSTRACT: Peronella japonica is a sand dollar with a zygote that develops into an abbreviated pluteus but then metamorphoses on day three. The adult rudiment formation is unique; it uses a median position of the hydrocoel and a stomodeum-like invagination of vestibule that covers the dorsal side of the hydrocoel. However, the developmental processes underlying coelom formation remain unclear. In this study, we examined this process by reconstructing three-dimensional images from serial sections of larvae. We show that the left coelom developed by both schizocoely and enterocoely from the archenteron tip, whereas the hydrocoel and right coelom formed by enterocoely from the archenteron. This coelom formation arranged the coelomic compartments directly along the adult oral-aboral axis by skipping the initial bilateral phases. Furthermore, our data indicate P. japonica retains ancestral asymmetry along the left-right axis in the location of the adult rudiment.
Developmental Dynamics 11/2011; 240(11):2432-9. · 2.54 Impact Factor
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ABSTRACT: The aquatic cyanobacterium Nostoc verrucosum forms macroscopic colonies, which consist of both cellular filaments and massive extracellular matrix material. In this study, the physiological features of N. verrucosum were investigated and compared with those of the anhydrobiotic cyanobacterium Nostoc commune. Nostoc verrucosum cells were sensitive to desiccation, but tolerant of freeze-thawing treatment in terms of both cell viability and photosynthetic O(2) evolution. Natural colonies of these cyanobacteria contained similar levels of chlorophyll a, carotenoids, the UV-absorbing pigments scytonemin and mycosporine-like amino acids, and uronic acid [a component of extracellular polysaccharides (EPS)]. EPS from both N. verrucosum and N. commune indicated low acidity and a high affinity for divalent cations, although their sugar compositions differed. The WspA protein, known to be a major component of the extracellular matrix of N. commune, was detected in N. verrucosum. Desiccation caused similarly high levels of trehalose accumulation in both cyanobacteria. Although previously considered relevant to anhydrobiosis in the terrestrial cyanobacterium N. commune, the data presented here suggest that extracellular matrix production and trehalose accumulation are not enough for standing extreme desiccation in N. verrucosum.
FEMS Microbiology Ecology 04/2011; 77(2):385-94. · 3.41 Impact Factor
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ABSTRACT: The micromere gene regulatory network (GRN) has been extensively examined using sea urchins belonging to the order Echinoida. To examine whether the network of Echinoida species is conserved in Scaphechinus mirabilis, an irregular echinoid of the order Clypeasteroida, the genes micro1, hesC, alx1, ets1, and delta were isolated from S. mirabilis and their expression patterns were compared with those from Hemicentrotus pulcherrimus, a species belonging to the order Echinoida. Data from this study suggest that the early GRN architecture had been largely established in a common ancestor of these two species. On the other hand, we found vegetal shifts in expression domains of some GRN members in H. pulcherrimus embryos compared to S. mirabilis embryos.
Developmental Dynamics 11/2010; 239(12):3391-403. · 2.54 Impact Factor
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ABSTRACT: We present the formation of hydrogen-content-controlled B(12)H(n) (+) clusters through the decomposition and ion-molecule reactions of the decaborane (B(10)H(14)) and diborane (B(2)H(6)) molecules in an external quadrupole static attraction ion trap. The hydrogen- and boron-contents of the B(10-y)H(x) (+) cluster are controlled by charge transfer from ambient gas ions. In the process of ionization, a certain number of hydrogen and boron atoms are detached from decaborane ions by the energy caused by charge transfer. The energy caused by the ion-molecule reactions also induces H atom detachment. Ambient gas of Ar leads to the selective generation of B(10)H(6) (+). The B(10)H(6) (+) clusters react with B(2)H(6) molecules, resulting in the selective formation of B(12)H(8) (+) clusters. Ambient gas of Ne (He) leads to the generation of B(10-y)H(x) (+) clusters with x=4-10 and y=0-1 (with x=2-10 and y=0-2), resulting in the formation of B(12)H(n) (+) clusters with n=4-8 (n=2,4-8). The introduction of ambient gas also increases the production of clusters. PBE0/6-311+G(d)//B3LYP/6-31G(d)-level density functional theory calculations are conducted to investigate the structure and the mechanism of formation of B(10-y)H(x) (+) and B(12)H(n) (+) clusters.
The Journal of chemical physics 08/2010; 133(7):074305. · 3.09 Impact Factor
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Kazushige Sato,
Satoshi Sekiguchi,
Naoki Kawagishi,
Yorihiro Akamatsu,
Kazuyuki Ishida,
Daizo Fukushima,
Shigeto Miyagi,
Ikuo Takeda, Masaaki Yamaguchi,
Shirou Oguma,
Keisei Fujimori,
Akira Sato,
Susumu Satomi
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ABSTRACT: Induction with basiliximab (BXM) has been confirmed as an effective treatment regimen for prophylaxis of acute cellular rejection (ACR). From 1991 to 2008, 116 living donor liver transplantations (LDLTs) were performed. Among these, 50 were included in this study. We compared calcineurin inhibitor plus steroid treatment without BXM (n = 14, control group) and with BXM (n = 36, BXM group). Although the rates of biopsied patients with abnormal serum biochemical tests (SBTs) were similar in the control (10/14, 71.4%) and BXM (21/36, 58.3%) groups, ACR was diagnosed in 9/10 (90.0%) patients in the control group compared with 4/21 (19.0%) patients in the BXM group. In accordance with the histopathological diagnosis, there was a significant difference in the ratios of peripheral CD4(+) CD25(+) T cells at five wk after LDLT between patients with and without ACR in the BXM group. Next, we divided the 32 patients without ACR in the BXM group into two groups: biopsied patients with abnormal SBTs and non-biopsied patients. The donor age of the biopsied patients was significantly higher than that of the non-biopsied patients. Induction with BXM reduced the incidence of ACR, and unique pathological phenomena responsible for graft dysfunction after LDLT with an increased incidence of abnormal SBTs were observed.
Clinical Transplantation 03/2010; 25(1):61-8. · 1.67 Impact Factor
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ABSTRACT: Deuterostomes comprise a monophyletic group of animals that include chordates, xenoturbellids, and the Ambulacraria, which consists of echinoderms and hemichordates. The ancestral chordate probably had 14 Hox genes aligned linearly along the chromosome, with the posterior six genes showing an independent duplication compared to protostomes. In contrast, ambulacrarians are characterized by a duplication of the posterior Hox genes, resulting in three genes known as Hox11/13a, Hox11/13b, and Hox11/13c. Here, we isolated 12 Hox genes from the hemichordate Balanoglossus misakiensis and found an extra Hox gene that has not been reported in hemichordates. The extra B. misakiensis gene was suggested to be Hox8 from paralog-characteristic residues in its hexapepetide motif and homeodomain and a comparison with Strongylocentrotus purpuratus Hox genes. Our data suggest that the ancestor of echinoderms and hemichordates may have had a full complement of 12 Hox genes.
Archiv für Entwickelungsmechanik der Organismen 09/2009; 219(7):377-82. · 1.77 Impact Factor
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ABSTRACT: Ab initio calculations indicated that icosahedral structure is more stable for B12Hn+ clusters with n = 6–12, but planar configuration is more stable for B12Hn+ with n = 0–5. Here, we report the energy barriers of structure transition by detaching H atoms from icosahedral B12H6+ to planar B12H5+, planar B12H4+, icosahedral B12H5+ or icosahedral B12H4+ cluster. We performed density functional theory calculations to explore the energy barriers and the reaction path of the structure transition. The resultant energy barriers are almost the same, enabling the transition to proceed and suggesting that the structure of B12Hn+ clusters is controlled by the number of hydrogen atoms n.
Journal of Physics Conference Series 07/2009; 176(1):012030.
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ABSTRACT: The micromeres of sea urchin embryos have two functions: to promote the autonomous differentiation of skeletogenic cells and to induce endomesodermal tissues. Micromere specification is controlled by a double-repression gate consisting of two repressors, Pmar1 and HesC. Micro1/pmar1 encodes a transcriptional repressor with a paired-type N-terminal homeodomain and two C-terminal serine-rich repeats, each of which includes a sequence similar to engrailed homology region 1, which interacts with the co-repressor Groucho. To understand the molecular mechanisms of the double-repression gate, we examined the correlation between the structure and function of micro1. Phenotypic and gene expression pattern analyses of embryos injected with mutated micro1 mRNA revealed that micro1 consists of five functional domain and motifs; namely, a DNA-binding homeodomain, a nuclear localization signal in the C-terminal flanking region of the homeodomain, and two eh1-like motifs plus a short C-terminal stretch that together mediate transcriptional repression. Our data suggest that micro1 represses target genes, including hesC, via two redundant means: its eh1-like and C-terminal motifs. The C-terminal motif requires unidentified sequences for micro1 function; a micro1 mutant with the motif but lacking the unidentified sequences failed to trigger the double-repression gate for early micromere regulatory genes, except for delta, though it did repress hesC. Our results suggest that the spatial regulation of primary mesenchyme cell specification genes, including tbr, alx1, and ets1, may be different from that of delta.
Mechanisms of development 07/2009; 126(8-9):611-23. · 2.83 Impact Factor
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ABSTRACT: Partitioning-defective (Par) genes were originally identified in Caenorhabditis elegans and are involved in asymmetric divisions of the egg. Recently, the expression and function of Par orthologs have been elucidated in deuterostomes, including vertebrates. In this study, we isolated three Par-related genes, Par-1, Par-6, and atypical protein kinase C (aPKC), from the sea urchin Hemicentrotus pulcherrimus and examined their temporal and spatial expression patterns during embryogenesis up to the pluteus stage. All three transcripts existed maternally in eggs and were uniformly expressed in cleavage-stage embryos. From the blastula to early gastrula stages, HpPar-1 expression was transiently restricted to the vegetal plate, including the primary mesenchyme cells (PMCs); this transient reduction was followed by uniform expression. HpPar-6 was expressed uniformly throughout development. In contrast, HpaPKC expression changed dramatically during development. At the blastula stage, HpaPKC expression was restricted to the vegetal region, including PMCs and the vegetal plate. During gastrulation, expression was maintained in PMCs and the archenteron tip, but expression declined at the late gastrula stage. From the prism stage, two cell types started to express HpaPKC: ectoderm cells interspersed in the ciliary band and skeletogenic cells at the posterior end of the larva. At the pluteus stage, the stomach began to express HpaPKC, in addition to the interspersed ciliary band and skeletogenic cells.
Gene Expression Patterns 06/2008; 8(5):323-30. · 2.02 Impact Factor
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ABSTRACT: We report the formation of icosahedral B(12)H(8) (+) through ion-molecule reactions of the decaborane ion [B(10)H(x)(+) (x=6-14)] with diborane (B(2)H(6)) molecules in an external quadrupole static attraction ion trap. The hydrogen content n of B(12)H(n)(+) is determined by the analysis of the mass spectrum. The result reveals that B(12)H(8)(+) is the main product. Ab initio calculations indicate that B(12)H(8)(+) preferentially forms an icosahedral structure rather than a quasiplanar structure. The energies of the formation reactions of B(12)H(14)(+) and B(12)H(12)(+) between B(10)H(x)(+) (x=6,8) ions, which are considered to be involved in the formation of B(12)H(n)(+), and a B(2)H(6) molecule are calculated. The calculations of the detachment pathway of H(2) molecules and H atoms from the product ions, B(12)H(14)(+) and B(12)H(12) (+), indicate that the intermediate state has a relatively low energy, enabling the detachment reaction to proceed owing to the sufficient reaction energy. This autodetachment of H(2) accounts for the experimental result that B(12)H(8)(+) is the most abundant product, even though it does not have the lowest energy among B(12)H(n)(+).
The Journal of Chemical Physics 04/2008; 128(12):124304. · 3.33 Impact Factor
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ABSTRACT: The canonical Wnt pathway plays a central role in specifying vegetal cell fate in sea urchin embryos. SpKrl has been cloned as a direct target of nuclear beta-catenin. Using Hemicentrotus pulcherrimus embryos, here we show that HpKrl controls the specification of secondary mesenchyme cells (SMCs) through both cell-autonomous and non-autonomous means. Like SpKrl, HpKrl was activated in both micromere and macromere progenies. To examine the functions of HpKrl in each blastomere, we constructed chimeric embryos composed of blastomeres from control and morpholino-mediated HpKrl-knockdown embryos and analyzed the phenotypes of the chimeras. Micromere-swapping experiments showed that HpKrl is not involved in micromere specification, while micromere-deprivation assays indicated that macromeres require HpKrl for cell-autonomous specification. Transplantation of normal micromeres into a micromere-less host with morpholino revealed that macromeres are able to receive at least some micromere signals regardless of HpKrl function. From these observations, we propose that two distinct pathways of endomesoderm formation exist in macromeres, a Krl-dependent pathway and a Krl-independent pathway. The Krl-independent pathway may correspond to the Delta/Notch signaling pathway via GataE and Gcm. We suggest that Krl may be a downstream component of nuclear beta-catenin required by macromeres for formation of more vegetal tissues, not as a member of the Delta/Notch pathway, but as a parallel effector of the signaling (Krl-dependent pathway).
Developmental Biology 03/2008; 314(2):433-42. · 4.07 Impact Factor
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ABSTRACT: We cloned eight Hox genes (MrHox1, MrHox2, MrHox4, MrHox5, MrHox7, MrHox8, MrHox9/10, and MrHox11/13c) from the sea lily Metacrinus rotundus, a member of the most basal group of the extant echinoderms. At the auricularia stage, before the formation of the pentaradial rudiment, four MrHox genes were expressed sequentially along the anteroposterior (AP) axis in the straightened mesodermal somatocoels in the order MrHox5, MrHox7, MrHox8, and MrHox9/10. The expression of MrHox7 and MrHox8 was detected as early as the hatching stage in the presumptive somatocoel region of the archenteral sac. MrHox5 was expressed in the anteriormost region of the somatocoels, where a stalk-related structure (the chambered organ) forms later. In addition to the mesodermal somatocoels, MrHox7 was expressed in the oral hood ectoderm, which gives rise to the adhesive pit. The expression of four other MrHox genes (MrHox1, MrHox2, MrHox4, and MrHox11/13c) was not detected in any of the larval stages we examined. In comparison with the mesodermal sea urchin Hox genes, the MrHox genes are expressed more posteriorly along the AP (oral-anal) axis than the sea urchin orthologs, implying that the evolution of the eleutherozoans was accompanied by a posteriorization of the larval body. Our study illuminates the possible body plan and Hox expression patterns of the ancestral echinoderm and sheds light on the larval body plan of the last common ancestor of the echinoderms and chordates.
Archiv für Entwickelungsmechanik der Organismen 01/2007; 216(12):797-809. · 1.77 Impact Factor
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ABSTRACT: In the sea urchin embryo, micromeres have two distinct functions: they differentiate cell autonomously into the skeletogenic mesenchyme cells and act as an organizing center that induces endomesoderm formation. We demonstrated that micro1 controls micromere specification as a transcriptional repressor. Because micro1 is a multicopy gene with at least six polymorphic loci, it has been difficult to consistently block micro1 function by morpholino-mediated knockdown. Here, to block micro1 function, we used an active activator of micro1 consisting of a fusion protein of the VP16 activation domain and the micro1 homeodomain. Embryos injected with mRNA encoding the fusion protein exhibited a phenotype similar to that of micromere-less embryos. To evaluate micro1 function in the micromere, we constructed chimeric embryos composed of animal cap mesomeres and a micromere quartet from embryos injected with the fusion protein mRNA. The chimeras developed into dauerblastulae with no vegetal structures, in which the micromere progeny constituted the blastula wall. We also analyzed the phenotype of chimeras composed of an animal cap and a mesomere expressing micro1. These chimeras developed into pluteus larvae, in which the mesomere descendants ingressed as primary mesenchyme cells and formed a complete set of skeletal rods. The hindgut and a part of the midgut were also generated from host mesomeres. However, the foregut and nonskeletogenic mesoderm were not formed in the larvae. From these observations, we conclude that micro1 is necessary and sufficient for both micromere differentiation and mid/hindgut-inducing activity, and we also suggest that micro1 may not fulfill all micromere functions.
Archiv für Entwickelungsmechanik der Organismen 10/2005; 215(9):450-59. · 1.77 Impact Factor
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ABSTRACT: In eastern Hokkaido, 60 to 80 kilometers above a subducting oceanic plate, tidal mudflats changed into freshwater forests during the first decades after a 17th-century tsunami. The mudflats gradually rose by a meter, as judged from fossil diatom assemblages. Both the tsunami and the ensuing uplift exceeded any in the region's 200 years of written history, and both resulted from a shallow plate-boundary earthquake of unusually large size along the Kuril subduction zone. This earthquake probably induced more creep farther down the plate boundary than did any of the region's historical events.
Science 01/2005; 306(5703):1918-20. · 31.20 Impact Factor
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ABSTRACT: The animal-vegetal axis of sea urchin embryos is morphologically apparent at the 16-cell stage, when the mesomeres, macromeres, and micromeres align along it. At this stage, the micromere is the only autonomously specified blastomere that functions as a signaling center. We used a subtraction PCR survey to identify the homeobox gene micro1 as a micromere-specific gene. The micro1 gene is a representative of a novel family of paired-like class homeobox genes, along with PlHbox12 from Paracentrotus lividus and pmar1 from Strongylocentrotus purpuratus. In the present study, we showed that micro1 is a multicopy gene with six or more polymorphic loci, at least three of which are clustered in a 30-kb region of the genome. The micro1 gene is transiently expressed during early cleavage stages in the micromere. Recently, nuclear beta-catenin was shown to be essential for the specification of vegetal cell fates, including micromeres, and the temporal and spatial coincidence of micro1 expression with the nuclear entry of beta-catenin is highly suggestive. We demonstrated that micro1 is a direct target of beta-catenin. In addition, we showed that micro1 is necessary and sufficient for micromere specification. These observations on the structure, regulation, and function of micro1 lead to the conclusion that micro1 and pmar1 (and potentially PlHbox12) are orthologous.
Archiv für Entwickelungsmechanik der Organismen 12/2004; 214(11):525-36. · 1.77 Impact Factor
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ABSTRACT: We describe development from fertilization to metamorphosis of the enteropneust hemichordate Balanoglossus misakiensis. This is the first report to describe the complete development of an indirect-developing hemichordate under laboratory conditions. Mature adults were induced to spawn by shifting the temperature of seawater from 23 to 28 degrees C. Eggs (200 microm diameter) were enclosed within a non-mucilaginous membrane, and dispersed readily in seawater. After artificial insemination, a fertilization envelope was elevated from the egg surface beneath the egg membrane; this was followed by the formation of the first and second polar bodies within the envelope. Zygotes cleaved at 20-min intervals to form blastulae, and gastrulation started 9 h after fertilization. Embryos hatched 1 day after fertilization to become typical feeding tornaria larvae. The larvae metamorphosed 7-10 days after fertilization without undergoing the first (Müller) or forth (Krohn) stage of indirect-developing hemichordate development. Larvae that were not fed failed to metamorphose. Juveniles completed adult body formation within a week of settling in sand at the bottom of the culture tube. We discuss heterochronical modifications of B. misakiensis development, and make the case for this species as a potential model organism for the investigation of indirect-developing hemichordates.
ZOOLOGICAL SCIENCE 06/2004; 21(5):533-40. · 0.95 Impact Factor
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ABSTRACT: The animal-vegetal (A-V) axis of sea urchin embryos is morphologically evident at the 16-cell stage of development. Mesomeres, macromeres, and micromeres are arrayed along the A-V axis. The vegetal micromere differentiates into the skeletogenic mesenchyme and functions as a signaling center. To date, no zygotic or maternally specified gene with restricted expression in the micromere at the 16-cell stage has been reported. We performed subtraction PCR and dot blot hybridization using poly(A)+ RNA extracted from the micromere (tester) and the mesomere (driver) in order to identify micromere-specific genes. Using a cDNA fragment identified in this screen, we isolated four similar but distinct cDNA clones from a library, which corresponded to a group of genes that we refer to as the micro1 family. The micro1 family encoded putative transcription factors with a homeodomain which had 87-95% identity between family members. The most highly conserved protein was encoded by PlHbox12 from Paracentrotus lividus (71-76% identity among family members). Northern blot hybridization and in situ hybridization demonstrated that micro1 was transiently activated during the early cleavage stages and that the transcript was restricted to the micromere. Thus, the expression domain was complementary to that of PlHbox12 along the A-V axis. The micro1 gene family has at least six loci, including polymorphic alleles, which are probably clustered in the genome. PlHbox12 and micro1 constitute a novel family of paired-like class homeobox genes. Phylogenetic analyses suggest that PlHbox12/micro1 evolved exceptionally rapidly.
Archiv für Entwickelungsmechanik der Organismen 03/2002; 212(1):1-10. · 1.77 Impact Factor
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ABSTRACT: In renal transplantation we usually diagnose an acute rejection by based on the results of a needle biopsy; however, this takes time and findings in some cases are not definite. We analysed the urine of renal recipients for the presence of donor DNA in an attempt to establish a diagnostic means of acute rejection. Sixty-four renal transplant recipients were examined. Thirty-seven patients had no trouble after transplantation and 22 patients developed acute rejection, diagnosed based on serum creatinine levels and/or needle biopsy findings of the graft. Five patients had drug-induced renal dysfunction. In female recipients with a male graft we examined urine for the presence of Y-chromosome (SRY and DYZ-1) and in recipients receiving a HLA mismatched graft we investigated the HLA-DR gene (DRB1) by the polymerase chain reaction (PCR) method. Among female recipients with a male graft there were 14 patients with stable renal function and SRY and DYZ-1 on Y-chromosome were negative in 13 (93%) and positive in one, whereas SRY and DYZ-1 of urine were positive in the four female patients with acute rejection and these DNA fragments disappeared in three after rejection therapy. One patient was subjected to haemodialysis. Among 23 recipients of a graft from HLA mismatched donors with stable renal function, DRB1 was negative in 21(91%). Among 18 patients with acute rejection DRB1 was positive in 16 (93%) and negative in two. These DNA fragments disappeared in 13 patients after rejection therapy. In all patients with drug-induced renal dysfunction donor-derived DNA was negative. Presence of donor-specific DNA in the urine of the recipient is associated strongly with acute rejection and analysis of DNA derived from donor cells in urine might be an effective and accurate method for the diagnosis of acute rejection of a renal transplant.
Clinical Transplantation 02/2002; 16 Suppl 8:45-50. · 1.67 Impact Factor
