bluuebunny/crossref_metadata_2025 huggingface dataset:
Follow‐up study investigating the benefits of phonological awareness intervention for children with spoken language impairment
Authors: Gillon Gail T.
Published: October 2002

The efficacy of phonological awareness intervention for children at risk for reading disorder has received increasing attention in the literature. This paper reports the follow‐up data for participants in the Gillon (2000a) intervention study. The performance of twenty, 5−7‐year‐old New Zealand children with spoken language impairment, who received phonological awareness intervention, was compared with the progress made by 20 children from a control group and 20 children with typical language development approximately 11 months post‐intervention. The children with spoken language impairment all had expressive phonological difficulties and demonstrated delay in early reading development. Treatment effects on strengthening phoneme‐grapheme connections in spelling development were also investigated. The results suggested that structured phonological awareness intervention led to sustained growth in phoneme awareness and word‐recognition performance. At the follow‐up assessment, the majority of the children who received intervention were reading at, or above, the level expected for their age on a measure of word recognition. The phonological awareness intervention also significantly strengthened phoneme‐grapheme connections in spelling as evidenced by improved non‐word spelling ability. In contrast, the control group of children with spoken language impairment who did not receive phonological awareness intervention showed remarkably little improvement in phoneme awareness over time and the majority remained poor readers. The results highlight the important role speech‐language therapists can play in enhancing the early reading and spelling development of children with spoken language impairment.
Arabidopsis ABI5 Subfamily Members Have Distinct DNA-Binding and Transcriptional Activities
Authors: Kim Soo Young , Ma Jianzhong , Perret Philippe , Li Zhongsen , Thomas Terry L.
Published: October 2002

A small family of novel basic leucine zipper proteins that includes abscisic acid (ABA)-INSENSITIVE 5 (ABI5) binds to the promoter region of the lea class gene Dc3. The factors, referred to as AtDPBFs (Arabidopsis Dc3 promoter-binding factors), were isolated from an immature seed cDNA library. AtDPBFs bind to the embryo specification and ABA-responsive elements in the Dc3 promoter and are unique in that they can interact with cis-elements that do not contain the ACGT core sequence required for the binding of most other plant basic leucine zipper proteins. Analysis of full-length cDNAs showed that at least five different Dc3 promoter-binding factors are present in Arabidopsis seeds; one of these, AtDPBF-1, is identical to ABI5. As expected, AtDPBF-1/ABI5 mRNA is inducible by exogenous ABA in seedlings. Despite the near identity in their basic domains, AtDPBFs are distinct in their DNA-binding, dimerization, and transcriptional activity.
Activation of Phospholipases C and D Is an Early Response to a Cold Exposure in Arabidopsis Suspension Cells
Authors: Ruelland Eric , Cantrel Catherine , Gawer Myriam , Kader Jean-Claude , Zachowski Alain
Published: October 2002

The signaling events generated by a cold exposure are poorly known in plants. We were interested in checking the possible activation of enzymes of the phosphoinositide signaling pathway in response to a temperature drop. In Arabidopsis suspension cells labeled with33PO4  3−, a cold treatment induces a rapid increase of phosphatidic acid (PtdOH) content. This production was due to the simultaneous activation of phospholipase C (through diacylglycerol kinase activity) and phospholipase D, as monitored by the production of inositol triphosphate and of transphosphatidylation product, respectively. Moreover, inhibitors of the phosphoinositide pathway and of diacylglycerol kinase reduced PtdOH production. Enzyme activation occurred immediately after cells were transferred to low temperature. The respective contribution of both kind of phospholipases in cold-induced production of PtdOH could be estimated. We created conditions where phospholipids were labeled with33PO4  3−, but with ATP being nonradioactive. In such conditions, the apparition of radioactive PtdOH reflected PLD activity. Thus, we demonstrated that during a cold stress, phospholipase D activity accounted for 20% of PtdOH production. The analysis of composition in fatty acids of cold-produced PtdOH compared with that of different phospholipids confirmed that cold-induced PtdOH more likely derived mainly from phosphoinositides. The addition of chemical reagents modifying calcium availability inhibited the formation of PtdOH, showing that the cold-induced activation of phospholipase pathways is dependent on a calcium entry.
Expression and Characterization of the Thylakoid Lumen Protease DegP1 from Arabidopsis
Authors: Chassin Yael , Kapri-Pardes Einat , Sinvany Galit , Arad Tal , Adam Zach
Published: October 2002

The Arabidopsis genome contains 14 genes encoding the serine protease DegP. Products of four of these genes are located in the chloroplast: three in the thylakoid lumen and one on the stromal side of the membrane. We expressed the gene encoding DegP1 as a His-tagged fusion protein in Escherichia coli, purified the protein by affinity chromatography, and characterized it biochemically. Size-exclusion chromatography suggested that DegP1 eluted from the column as a mixture of monomers and hexamers. Proteolytic activity was characterized using β-casein as a model substrate. DegP1 demonstrated concentration-dependent activity, a pH optimum of 6.0 and increasing activity at elevated temperatures. DegP1 was capable of degrading two lumenal proteins, plastocyanin and OE33, suggesting a role as a general-purpose protease in the thylakoid lumen. The results of this work are discussed in the context of the recent elucidation of the structure of the E. coli homolog and the possible physiological role of the protease in the chloroplast lumen.
Reflections on customer knowledge management in e‐business
Authors: Rowley Jennifer E.
Published: October 2002

Customer knowledge is an important asset for all businesses. The rhetoric of e‐business emphasises the opportunities for knowing customers in the digital economy. This article sets the context with a brief summary of the key characteristics of the knowledge management paradigm. This is used as a platform for the themes that form the core of this article: defining the knowledge that the organisation requires; knowledge tools and the relationships between data, information and knowledge; the role of customer communities in CKM; bounding and structuring organisational knowledge communities; ownership of knowledge assets; integrating customer knowledge across channels; and comparing customer knowledge management with customer relationship management. The overarching message of the article is that customer knowledge management is not just about data. Organisations need to develop strategies that enable them to capitalise on the dynamic integration of systems and people.
Modulation of Acetaminophen-Induced Hepatotoxicity by the Xenobiotic Receptor CAR
Authors: Zhang Jun , Huang Wendong , Chua Steven S. , Wei Ping , Moore David D.
Published: October 2002

We have identified the xenobiotic receptor CAR (constitutive androstane receptor) as a key regulator of acetaminophen metabolism and hepatotoxicity. Known CAR activators as well as high doses of acetaminophen induced expression of three acetaminophen-metabolizing enzymes in wild-type but not in CAR null mice, and the CAR null mice were resistant to acetaminophen toxicity. Inhibition of CAR activity by administration of the inverse agonist ligand androstanol 1 hour after acetaminophen treatment blocked hepatotoxicity in wild type but not in CAR null mice. These results suggest an innovative therapeutic approach for treating the adverse effects of acetaminophen and potentially other hepatotoxic agents.
Specification of Jaw Subdivisions by
Dlx
Genes
Authors: Depew Michael J. , Lufkin Thomas , Rubenstein John L. R.
Published: October 2002

The success of vertebrates was due in part to the acquisition and modification of jaws. Jaws are principally derived from the branchial arches, embryonic structures that exhibit proximodistal polarity. To investigate the mechanisms that specify the identity of skeletal elements within the arches, we examined mice lacking expression of
Dlx5
and
Dlx6
, linked homeobox genes expressed distally but not proximally within the arches.

Dlx5/6
–/–

mutants exhibit a homeotic transformation of lower jaws to upper jaws. We suggest that nested
Dlx
expression in the arches patterns their proximodistal axes. Evolutionary acquisition and subsequent refinement of jaws may have been dependent on modification of
Dlx
expression.
Large-scale preparation of α-D-(14)-oligogalacturonic acids from pectic acid
Authors: Fan Hong-Ni , Liu Mei-Zheng , Lee Yuan C
Published: October 2002

An efficient and inexpensive method for large-scale preparation of α-D-(1[Formula: see text]4)-oligogalacturonic acids (oligo-GalA), up to DP 5, from pectic acid is described. Pectic acid was digested with a commercially available pectinase to yield a mixture of oligo-GalA, which was effectively separated by a combination of low-pressure  size-exclusion chromatography based on ion-exchange chromatography to obtain pure oligo-GalA of DP 2-5. Key words: pectic acid, galacturonic acid, galabiose, galatriose, pectinase.
Novel substrates for efficient enzymatic transglycosylation byBacillus circulans
Authors: Komba Shiro , Ito Yukishige
Published: October 2002

To develop transglycosylation for efficient preparation of N-acetyllactosamine (Galβ(1[Formula: see text]4)GlcNAc, LacNAc), β-galactosidase mediated transglycosylation using novel substrates Bacillus Circulans was explored. To make transglycosylation entropically favorable over hydrolysis, donor (lactose or galactose) and acceptor (N-acetyl glucosamine, GlcNAc) components were connected to a single molecule. For that purpose, 1,2- and 1,3-benzene dimethanol and 2-hydroxy-5-nitro- and 5-hydroxy-2-nitro-benzyl alcohol were screened as linkers and enzymatic transglycosylation was examined under several conditions. In the case of 2-hydroxy-5-nitro-benzyl connected substrate 40, an indication of the occurrence of intramolecular transglycosylation was observed, and the desired product (58) was obtained in 26% isolated yield. The same reaction in the presence of CMP sialic acid and α-(2[Formula: see text]6)-sialyltransferase gave sialyl LacNAc 87 in one pot in 39% isolated yield. Additionally, the effect of the C-2 substituent of the acceptor component was briefly examined using substrates containing NHAlloc (72), NHTroc (73), and N3(74) groups. Although the occurrence of intramolecular transglycosylation was not clear in these cases, disaccharides 8183 were obtained in reasonable yields.Key words: galactosidase, intramolecular transglycosylation, N-acetyllactosamine, sialyltransferase.
Environmental controls on soil CO2 flux following fire in black spruce, white spruce, and aspen stands of interior Alaska
Authors: O'Neill Katherine P , Kasischke Eric S , Richter Daniel D
Published: October 2002

Boreal forests contain large amounts of stored soil carbon and are susceptible to periodic disturbance by wildfire. This study evaluates the relationship between post-fire changes in soil temperature, moisture, and CO2 exchange in paired burned and control stands of three Alaskan forest systems: Picea mariana (Mill.) BSP, Picea glauca (Moench) Voss, and Populus tremuloides Michx. In these systems, the environmental factor that most directly controlled rates of carbon exchange varied depending upon burn status and soil drainage. In mature unburned stands, CO2 flux was highly correlated with seasonal patterns of soil temperature. Following fire, these soils became significantly warmer, and carbon exchange became more sensitive to fluctuations in surface moisture conditions. The effect of fire on soil climate was most pronounced in the P. mariana stands, which experienced a mean seasonal temperature increase of 58°C in the upper 1 m of the soil profile, a 200% increase in the rate of active layer thaw, and a reduction in mean surface moisture potential. Evidence from soil CO2 profiles suggests that these environmental changes may have resulted in enhanced decomposition of carbon previously immobilized by permafrost, potentially transforming a landscape that was once a net sink for carbon into a carbon source.
HIGHER MORTALITY OF THE YOUNGEST ORGANISMS PREDICTED BY THE PENNA AGING MODEL
Authors: ŁASZKIEWICZ A. , NIEWCZAS E. , SZYMCZAK SZ. , KURDZIEL A. , CEBRAT S.
Published: October 2002

We have simulated the evolution of population using the Penna model of aging. In populations of diploid organisms, without recombination between haplotypes or with low cross-over rate, a specific distribution of defective genes has been established. As an effect, relatively higher mortality is observed during the earliest stages of life. When two independently evolving populations were mixed and co-evolved in one environment without crossbreeding, one population won after several generations and this winning population showed stronger "early" death effect. We conclude that in the environmentally limited size of a population (in the model limit set by Verhulst factor) it is a better strategy to sacrifice younger individuals — higher fractions of such populations reach the reproduction age.
PERCOLATION AND GALAM THEORY OF MINORITY OPINION SPREADING
Authors: STAUFFER DIETRICH
Published: October 2002

The way in which an opinion rejecting reform can finally become the consensus of everyone was studied by Galam (2002) in a probabilistic model. We now replace his clusters by those formed via random percolation by letting particles diffuse on a lattice. Galam's rejection of reform is reproduced below the percolation threshold, whereas at and above the threshold, approval of a reform also becomes possible.
INERTIAL FORCES AS VIEWED FROM THE ADM SLICING AND THEIR BEHAVIOUR FOR PARTICLES IN NON-CIRCULAR GEODESICS
Authors: PRASANNA A. R.
Published: October 2002

Considering the definition of inertial forces acting on a test particle, following non-circular geodesics, in static and stationary space–times, we show that the centrifugal force reversal occurs only in the case of particles following prograde orbits around black holes. We first rewrite the covariant expressions for the acceleration components in terms of the lapse function, shift vector and the three-metric γij, using the ADM 3 + 1 splitting and use these, for different cases as given by pure radial motion, pure azimuthal motion and the general non-circular motion. It is found that the reversal occurs between 2m and 3m, only when the azimuthal angular velocity of the particle supersedes the radial velocity, which indeed depends upon the physical parameters E, ℓ and the Kerr parameter a.
EFFECT OF SAMARIUM SUBSTITUTION ON PHYSICAL AND MICROSTRUCTURAL PROPERTIES OF THE Ba0.95Sr0.05TiO3 SYSTEM
Authors: THAKUR O. P. , PRAKASH CHANDRA
Published: October 2002

The effect of samarium substitution on structural properties of BST system is studied. X-ray analysis shows the single phase for all the samples with tetragonal structure. The physical and structural properties are discussed in terms of defect chemistry.
Lentiviral vectors pseudotyped with a modified RD114 envelope glycoprotein show increased stability in sera and augmented transduction of primary lymphocytes and CD34+ cells derived from human and nonhuman primates
Authors: Sandrin Virginie , Boson Bertrand , Salmon Patrick , Gay Wilfried , Nègre Didier , Le Grand Roger , Trono Didier , Cosset François-Loı̈c
Published: October 2002

Generating lentiviral vectors pseudotyped with different viral glycoproteins (GPs) may modulate the physicochemical properties of the vectors, their interaction with the host immune system, and their host range. We have investigated the capacity of a panel of GPs of both retroviral (amphotropic murine leukemia virus [MLV-A]; gibbon ape leukemia virus [GALV]; RD114, feline endogenous virus) and nonretroviral (fowl plague virus [FPV]; Ebola virus [EboV]; vesicular stomatitis virus [VSV]; lymphocytic choriomeningitis virus [LCMV]) origins to pseudotype lentiviral vectors derived from simian immunodeficiency virus (SIVmac251). SIV vectors were efficiently pseudotyped with the FPV hemagglutinin, VSV-G, LCMV, and MLV-A GPs. In contrast, the GALV and RD114 GPs conferred much lower infectivity to the vectors. Capitalizing on the conservation of some structural features in the transmembrane domains and cytoplasmic tails of the incorporation-competent MLV-A GP and in RD114 and GALV GPs, we generated chimeric GPs encoding the extracellular and transmembrane domains of GALV or RD114 GPs fused to the cytoplasmic tail (designated TR) of MLV-A GP. Importantly, SIV-derived vectors pseudotyped with these GALV/TR and RD114/TR GP chimeras had significantly higher titers than vectors coated with the parental GPs. Additionally, RD114/TR-pseudotyped vectors were efficiently concentrated and were resistant to inactivation induced by the complement of both human and macaque sera, indicating that modified RD114 GP-pseudotyped lentiviral vectors may be of particular interest for in vivo gene transfer applications. Furthermore, as compared to vectors pseudotyped with other retroviral GPs or with VSV-G, RD114/TR-pseudotyped vectors showed augmented transduction of human and macaque primary blood lymphocytes and CD34+ cells.
High-dose cyclophosphamide for refractory autoimmune hemolytic anemia
Authors: Moyo Victor M. , Smith Douglas , Brodsky Isadore , Crilley Pamela , Jones Richard J. , Brodsky Robert A.
Published: October 2002

High-dose cyclophosphamide, without stem cell rescue, has been used successfully to treat aplastic anemia and other autoimmune disorders. To determine the safety and efficacy of high-dose cyclophosphamide among patients with severe refractory autoimmune hemolytic anemia, we treated 9 patients with cyclophosphamide (50 mg  ·  kg−1  ·  d−1 for 4 days) who had failed a median of 3 (range, 1-7) other treatments. The median hemoglobin before treatment was 6.7 g/dL (range, 5-10 g/dL). The median time to reach an absolute neutrophil count of 500/μL or greater was 16 days (range, 12-18 days). Six patients achieved complete remission (normal untransfused hemoglobin for age and sex), and none have relapsed after a median follow-up of 15 months (range, 4-29 months). Three patients achieved and continue in partial remission (hemoglobin at least 10 g/dL without transfusion support). High-dose cyclophosphamide was well tolerated and induced durable remissions in patients with severe refractory autoimmune hemolytic anemia.
The role of cytokines in classical Hodgkin lymphoma
Authors: Skinnider Brian F. , Mak Tak W.
Published: October 2002

The clinical and pathologic features of classical Hodgkin lymphoma (cHL) reflect an abnormal immune response that is thought to be due to the elaboration of a variety of cytokines by the malignant Reed-Sternberg (RS) cells or surrounding tissues. The majority of cHL cases are characterized by expression of tumor necrosis factor receptor (TNFR) family members and their ligands, as well as an unbalanced production of Th2 cytokines and chemokines. Activation of TNFR members results in constitutive activation of nuclear factor-κB (NF-κB), a transcription factor important for the in vitro and in vivo growth of RS cell lines. The expression of Th2 cytokines and chemokines leads to the reactive infiltrate of eosinophils, Th2 cells, and fibroblasts characteristic of cHL, and can also contribute to a local suppression of Th1 cell–mediated cellular immune response. Another particularly important growth and survival factor for RS cell lines is the Th2 cytokine interleukin 13, which is also commonly expressed by primary RS cells. In approximately 40% of cHL cases, the presence of Epstein-Barr virus influences the Th1/Th2 balance toward the production of Th1 cytokines and chemokines, but this shift is apparently insufficient for the stimulation of an effective antitumor cell-mediated immune response. This review summarizes the current literature on cytokine expression by and activity on RS cell lines and primary cHL tissues, examines cytokine signaling pathways in RS cells, and discusses the role that cytokines play in the specific clinical and pathologic features of cHL.
Von Willebrand factor–cleaving protease (ADAMTS13) in thrombocytopenic disorders: a severely deficient activity is specific for thrombotic thrombocytopenic purpura
Authors: Bianchi Valentina , Robles Rodolfo , Alberio Lorenzo , Furlan Miha , Lämmle Bernhard
Published: October 2002

A severe deficiency in von Willebrand factor–cleaving protease (ADAMTS13) activity (< 5% that in normal plasma) has been observed in most patients with a diagnosis of thrombotic thrombocytopenic purpura (TTP) but not in those with a diagnosis of hemolytic uremic syndrome. However, ADAMTS13 deficiency has been claimed not to be specific for TTP, since it was observed in various thrombocytopenic and other conditions. We studied 68 patients with thrombocytopenia due to severe sepsis or septic shock (n = 17), heparin-induced thrombocytopenia (n = 16), idiopathic thrombocytopenic purpura (n = 10), or other hematologic (n = 15) or miscellaneous conditions (n = 10). Twelve of the 68 patients had subnormal levels of ADAMTS13 activity (≤ 30%), but none had less than 10%. Thus, the study showed that ADAMTS13 activity is decreased in a substantial proportion of patients with thrombocytopenia of various causes. A severe deficiency of ADAMTS13 (< 5%), identified in more than 120 patients during 1996 to 2001 in our laboratory, is specific for a thrombotic microangiopathy commonly labeled TTP.
Targeted removal of PML-RARα protein is required prior to inhibition of histone deacetylase for overcoming all-trans retinoic acid differentiation resistance in acute promyelocytic leukemia
Authors: Jing Yongkui , Xia Lijuan , Waxman Samuel
Published: October 2002

All-trans retinoic acid (tRA)–induced differentiation in NB4 cells, a cell line derived from an acute promyelocytic leukemia patient with t(15;17) translocation, is markedly facilitated by sodium butyrate (NaB), a histone deacetylase inhibitor (HDACI), or by hexamethylene bisacetamide (HMBA), a non–HDACI tRA-differentiation inducer, as determined by nitroblue tetrazolium reduction. The tRA-induced expression of RIG-G, Bfl-1/A1, and p21waf1 and, to a lesser extent, of CCAAT/enhancer binding protein–ε (C/EBPε) are also enhanced by such combined treatments. Both responses are associated with a facilitated diminution of the leukemogenic PML-RARα protein and retained ΔPML-RARα, a cleavage product. Treatment with tRA in tRA differentiation–resistant NB4 subclones R4 and MR-2 does not result in PML-RARα diminution and the tested gene expressions. Moreover, the addition of HMBA or NaB with tRA results in only minimal increase of differentiation in the tRA differentiation–resistant subclones. The increases in acetylated histone H3 (AcH3) and AcH4 in NaB-treated NB4, R4, and MR-2 cells are similar and do not correlate with the extent of differentiation induction when NaB and HMBA are given in combination with tRA. Arsenic trioxide (As2O3) treatment results in the total degradation of PML-RARα without increasing AcH3 or AcH4 or inducing differentiation in R4 cells. As2O3 in combination with tRA induces gene (Bfl-1/A1 and C/EBPε) expression and partial differentiation. Both NaB and HMBA addition to As2O3-plus-tRA–treated R4 cells further enhances differentiation. These results suggest that elimination of the dominant negative PML-RARα protein is required prior to inhibition of histone deacetylase to fully overcome tRA-differentiation resistance in APL cells.
Role of factor XIII in fibrin clot formation and effects of genetic polymorphisms
Authors: Ariëns Robert A. S. , Lai Thung-Shenq , Weisel John W. , Greenberg Charles S. , Grant Peter J.
Published: October 2002

Factor XIII and fibrinogen are unusual among clotting factors in that neither is a serine protease. Fibrin is the main protein constituent of the blood clot, which is stabilized by factor XIIIa through an amide or isopeptide bond that ligates adjacent fibrin monomers. Many of the structural and functional features of factor XIII and fibrin(ogen) have been elucidated by protein and gene analysis, site-directed mutagenesis, and x-ray crystallography. However, some of the molecular aspects involved in the complex processes of insoluble fibrin formation in vivo and in vitro remain unresolved. The findings of a relationship between fibrinogen, factor XIII, and cardiovascular or other thrombotic disorders have focused much attention on these 2 proteins. Of particular interest are associations between common variations in the genes of factor XIII and altered risk profiles for thrombosis. Although there is much debate regarding these observations, the implications for our understanding of clot formation and therapeutic intervention may be of major importance. In this review, we have summarized recent findings on the structure and function of factor XIII. This is followed by a review of the effects of genetic polymorphisms on protein structure/function and their relationship to disease.
Pro-oxidant and cytotoxic effects of circulating heme
Authors: Jeney Viktória , Balla József , Yachie Akihiro , Varga Zsuzsa , Vercellotti Gregory M. , Eaton John W. , Balla György
Published: October 2002

Numerous pathologies may involve toxic side effects of free heme and heme-derived iron. Deficiency of the heme-catabolizing enzyme, heme oxygenase-1 (HO-1), in both a human patient and transgenic knockout mice leads to an abundance of circulating heme and damage to vascular endothelium. Although heme can be directly cytotoxic, the present investigations examine the possibility that hemoglobin-derived heme and iron might be indirectly toxic through the generation of oxidized forms of low-density lipoprotein (LDL). In support, hemoglobin in plasma, when oxidized to methemoglobin by oxidants such as leukocyte-derived reactive oxygen, causes oxidative modification of LDL. Heme, released from methemoglobin, catalyzes the oxidation of LDL, which in turn induces endothelial cytolysis primarily caused by lipid hydroperoxides. Exposure of endothelium to sublethal concentrations of this oxidized LDL leads to induction of both HO-1 and ferritin. Similar endothelial cytotoxicity was caused by LDL isolated from plasma of an HO-1–deficient child. Spectral analysis of the child's plasma revealed a substantial oxidation of plasma hemoglobin to methemoglobin. Iron accumulated in the HO-1–deficient child's LDL and several independent assays revealed oxidative modification of the LDL. We conclude that hemoglobin, when oxidized in plasma, can be indirectly cytotoxic through the generation of oxidized LDL by released heme and that, in response, the intracellular defense—HO-1 and ferritin—is induced. These results may be relevant to a variety of disorders—such as renal failure associated with intravascular hemolysis, hemorrhagic injury to the central nervous system, and, perhaps, atherogenesis—in which hemoglobin-derived heme may promote the formation of fatty acid hydroperoxides.
Hepatic sinusoidal obstruction after gemtuzumab ozogamicin (Mylotarg) therapy
Authors: Rajvanshi Pankaj , Shulman Howard M. , Sievers Eric L. , McDonald George B.
Published: October 2002

Gemtuzumab ozogamicin (Mylotarg) targets leukemia cells expressing the CD33 receptor by means of a monoclonal antibody conjugated to a cytotoxic agent, calicheamicin. Treatment of acute myeloid leukemia (AML) with gemtuzumab ozogamicin may result in liver injury. We reviewed the course of 23 patients who were given gemtuzumab ozogamicin for AML that had relapsed after hematopoietic cell transplantation. Liver toxicity was assessed through physical examination, serum tests, histologic examination, and hepatic venous pressure measurements. Liver injury developed in 11 patients after gemtuzumab ozogamicin administration; it was manifested as weight gain, ascites, and jaundice in 7 patients. Seven patients died with persistent liver dysfunction and either multiorgan failure or sepsis at a median of 40 days after gemtuzumab ozogamicin infusion. Portal pressure measurements were elevated in 2 patients. Results of liver histologic examination in 5 patients showed sinusoidal injury with extensive sinusoidal fibrosis, centrilobular congestion, and hepatocyte necrosis. Six patients experienced AML remission that was sustained for at least 60 days after gemtuzumab ozogamicin infusion. In summary, hepatic sinusoidal liver injury developed after gemtuzumab ozogamicin infusion. Histology showed striking deposition of sinusoidal collagen, suggesting that gemtuzumab ozogamicin targets CD33+ cells residing in hepatic sinusoids as the mechanism for its hepatic toxicity.
Role of the docking protein Gab2 in β1-integrin signaling pathway-mediated hematopoietic cell adhesion and migration
Authors: Yu Wen-Mei , Hawley Teresa S. , Hawley Robert G. , Qu Cheng-Kui
Published: October 2002

Gab2, a newly identified pleckstrin homology domain-containing docking protein, is a major binding protein of SHP-2 tyrosine phosphatase in interleukin (IL)-3–stimulated hematopoietic cells. Its signaling mechanism remains largely unknown. We report here an important regulatory role for Gab2 in β1 integrin signaling pathway that mediates hematopoietic cell adhesion and migration. Cross-linking of the β1 integrin on Ba/F3 cells induced rapid tyrosine phosphorylation of Gab2 and its association with Syk kinase, SHP-2 phosphatase, and the p85 subunit of phosphatidylinositol (PI)-3 kinase. In addition, Gab2 was also constitutively associated with SHP-1 phosphatase via its C-terminal Src homology 2 domain. Overexpression of the pleckstrin homology domain or a mutant Gab2 molecule lacking SHP-2 binding sites resulted in significant reductions in Ba/F3 cell adhesion and migration. Biochemical analyses revealed that enforced expression of Gab2 mutant molecules dramatically reduced β1-integrin ligation-triggered PI3 kinase activation, whereas Erk kinase activation remained unaltered. Furthermore, transduction of primary hematopoietic progenitor cells from viable motheaten mice with these mutant Gab2 molecules also significantly ameliorated their enhanced migration capacity associated with theSHP1 gene mutation. Taken together, these results suggest an important signaling role for Gab2 in regulating hematopoietic cell adhesion and migration.
Role of the Src family kinase Lyn in TxA2 production, adenosine diphosphate secretion, Akt phosphorylation, and irreversible aggregation in platelets stimulated with γ-thrombin
Authors: Cho Moon J. , Pestina Tamara I. , Steward Shirley A. , Lowell Clifford A. , Jackson Carl W. , Gartner T. Kent
Published: October 2002

Members of the Src family of kinases are abundant in platelets. Although their localization is known, their role(s) in platelet function are not well understood. Lyn is a Src-family kinase that participates in signal transduction pathways elicited by collagen-related peptide; it has also been implicated through biochemical studies in the regulation of von Willebrand factor signaling. Here, we provide evidence that Lyn plays a role in γ-thrombin activation of platelets. Unlike the wild-type platelets, platelets from Lyn-deficient mice do not undergo irreversible aggregation, produce thromboxane A2, or secrete adenosine diphosphate in response to submaximal γ-thrombin concentrations that cause secretion-dependent irreversible aggregation. Phosphorylation of Akt, a downstream effector of phosphatidylinositol 3-kinase, also requires a higher concentration of γ-thrombin in Lyn-deficient platelets than in wild-type platelets. These findings demonstrate that Lyn signaling is required for thrombin induction of secretion-dependent platelet aggregation. Specifically, Lyn is required under these conditions to enable thrombin-induced TxA2 production and adenosine diphosphate secretion, necessary steps in secretion-dependent platelet aggregation.
Factor XI deficiency in French Basques is caused predominantly by an ancestral Cys38Arg mutation in the factor XI gene
Authors: Zivelin Ariella , Bauduer Frederic , Ducout Louis , Peretz Hava , Rosenberg Nurit , Yatuv Rivka , Seligsohn Uri
Published: October 2002

Inherited factor XI deficiency is an injury-related bleeding disorder that is rare in most populations except for Jews, in whom 2 mutations, a stop mutation in exon 5 (type II) and a missense mutation in exon 9 (type III), predominate. Recently, a cluster of 39 factor XI–deficient patients was described in the Basque population of Southwestern France. In this study, we determined the molecular basis of factor XI deficiency in 16 patients belonging to 12 unrelated families of French Basque origin. In 8 families, a nucleotide 209T>C transition in exon 3 was detected that predicts a Cys38Arg substitution. Four additional novel mutations in the factor XI gene, Cys237Tyr, Tyr493His, codon 285delG, and IVS6 + 3A>G, were identified in 4 families. Expression studies showed that Cys38Arg and Cys237Tyr factor XI were produced in transfected baby hamster kidney cells, but their secretion was impaired. Cells transfected with Tyr493His contained reduced amounts of factor XI and displayed decreased secretion. A survey of 206 French Basque controls for Cys38Arg revealed that the prevalence of the mutant allele was 0.005. Haplotype analysis based on the study of 10 intragenic polymorphisms was consistent with a common ancestry (a founder effect) for the Cys38Arg mutation.
Impact of antithrombin deficiency in thrombogenesis: lipopolysaccharide and stress-induced thrombus formation in heterozygous antithrombin-deficient mice
Authors: Yanada Masamitsu , Kojima Tetsuhito , Ishiguro Kazuhiro , Nakayama Yukiko , Yamamoto Koji , Matsushita Tadashi , Kadomatsu Kenji , Nishimura Masahiko , Muramatsu Takashi , Saito Hidehiko
Published: October 2002

Antithrombin (AT) deficiency is an autosomal disorder associated with venous thromboembolism. However, a diagnosis of homozygous AT deficiency is seldom made. Most patients are heterozygous and have approximately 50% AT activities, and they are at higher risk for the development of thromboembolism. Through gene targeting we generated AT-deficient mice and previously reported that completely AT-deficient mice could not survive the prenatal period because of extensive thrombosis in the myocardium and liver sinusoids. In contrast, heterozygous AT-deficient mice with 50% AT activities have not shown spontaneous thromboembolic episodes. To demonstrate a thrombotic tendency in heterozygous AT deficiency, we challenged heterozygous AT-deficient mice (AT+/− mice) with the administration of lipopolysaccharide (LPS) or with restraint stress by immobilization. LPS injection markedly induced fibrin deposition in the kidney glomeruli, myocardium, and liver sinusoids in AT+/− mice compared with wild-type mice (AT+/+ mice). Restraint stress tests were performed by placing mice in 50-mL conical centrifuge tubes for 20 hours. Fibrin deposition was observed in the kidney ofAT+/+ and AT+/− mice, but AT+/−mice exhibited more extensive fibrin deposition thanAT+/+ mice. After prophylactic administration of human AT concentrates to increase plasma AT activities of AT+/−mice, LPS-induced fibrin deposition was effectively prevented. These results suggest that heterozygous AT deficiency is significantly associated with a tendency toward thrombosis formation in the kidney. The AT+/− mouse thus is a useful model for studying the effect of environmental or genetic risk factors on thrombogenesis.
High frequency of protein Z deficiency in patients with unexplained early fetal loss
Authors: Gris Jean-Christophe , Quéré Isabelle , Dechaud Hervé , Mercier Eric , Pinçon Caroline , Hoffet Médéric , Vasse Marc , Marès Pierre
Published: October 2002

The protein Z–protein Z-dependent inhibitor complex is a factor Xa inhibitor. Protein Z deficiencies have recently been described in patients with ischemic stroke. As placenta infarction leads to poor pregnancy outcome, we studied protein Z plasma concentrations in nonthrombotic, nonthrombophilic consecutive patients with unexplained pregnancy wastage. A significant amount of protein Z deficiencies was only found in the early fetal loss group (< 1 mg/L; 44 of 200,P < 10−4) and mainly in the case of fetal demise between the beginning of the 10th and the end of the 15th week of gestation (odds ratio, 6.7 [3.1-14.8],P < 10−3). These deficiencies were not due to partial vitamin K1 deficiency, and at least some of them were constitutional ones. In women, protein Z deficiency may induce an enhanced risk of severe placental insufficiency soon after the connection of maternal and fetal circulations.
A prospective study of venous thromboembolism in relation to factor V Leiden and related factors
Authors: Folsom Aaron R. , Cushman Mary , Tsai Michael Y. , Aleksic Nena , Heckbert Susan R. , Boland Lori L. , Tsai Albert W. , Yanez N. David , Rosamond Wayne D.
Published: October 2002

The aim of this study was to examine the occurrence of venous thromboembolism (VTE) in relation to factor V–related risk factors. Using a nested case-control design combining 2 population-based prospective studies, we measured factor V Leiden, HR2 haplotype, activated protein C (APC) resistance, and plasma factor V antigen in 335 participants who developed VTE during 8 years of follow-up and 688 controls. The overall odds ratio (OR) of VTE was 3.67 (95% CI, 2.20-6.12) in participants carrying factor V Leiden compared with noncarriers. APC resistance measured after predilution with factor V–deficient plasma conferred an OR of 2.58 (95% CI, 1.62-4.10). All 3 participants homozygous for the HR2 haplotype had a VTE, and the OR of VTE for homozygosity was estimated to be 5.5 (95% CI, 2.45-12.5). Carriers of the HR2 haplotype otherwise were not at increased risk of VTE overall (OR = 1.05; 95% CI, 0.64-1.72), but double heterozygotes for HR2 and factor V Leiden carried an OR of idiopathic VTE of 16.3 (95% CI, 1.7-159) compared with noncarriers. Factor V antigen also was not associated with VTE overall, but for participants with the combination of high factor V antigen plus factor V Leiden the OR of idiopathic VTE was 11.5 (95% CI, 4.2-31.4). In the general population, APC resistance and factor V Leiden were important VTE risk factors; homozygosity for the HR2 haplotype may be a risk factor but was rare; otherwise, HR2 haplotype and factor V antigen were not risk factors except in carriers of factor V Leiden.
Level of galactosylation determines cryoglobulin activity of murine IgG3 monoclonal rheumatoid factor
Authors: Kuroki Aki , Kuroda Yasuhiro , Kikuchi Shuichi , Lajaunias Frédéric , Fulpius Thierry , Pastore Yves , Fossati-Jimack Liliane , Reininger Luc , Toda Toho , Nakata Munehiro , Kojima Naoya , Mizuochi Tsuguo , Izui Shozo
Published: October 2002

Autoantibodies of the cryoprecipitating IgG3 isotype have been shown to play a significant role in the development of murine lupus–like autoimmune syndrome. At present, the structural basis of IgG3 cryoprecipitation and its role in autoantibody pathogenicity remain to be defined. Using molecular variants of an IgG3 monoclonal rheumatoid factor, 6-19, derived from an autoimmune MRL-Faslpr mouse, we have investigated the implication of charged residues in the heavy-chain variable (VH) region, potential CH3-linked oligosaccharides, and galactosylation of CH2-linked oligosaccharides in its cryoglobulin activity. The cryoglobulin activity of the IgG3 6-19 mutant bearing more negatively charged residues at VH 6 and 23 was found to be reduced but still highly significant, whereas that of the mutant lacking a potential CH3 glycosylation site remained unchanged. In marked contrast, IgG3 6-19 variants obtained from 6-19 heavy-chain transgenic mice displayed barely detectable cryoglobulin activity associated with an increased level of galactosylation in the CH2 oligosaccharide side chains. Thus, our data strongly suggest that the cryoglobulin activity of IgG3 6-19 autoantibody is critically determined by levels of galactosylation in the CH2 oligosaccharide side chains, whereas VH residues play a secondary role in 6-19 IgG3 cryoglobulin activity.
Involvement of protein kinase C and phosphatidylinositol 3–kinase pathways in the survival of B-cell chronic lymphocytic leukemia cells
Authors: Barragán Montserrat , Bellosillo Beatriz , Campàs Clara , Colomer Dolors , Pons Gabriel , Gil Joan
Published: October 2002

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived CD5+ B lymphocytes. TPA (12-O-tetradecanoylphorbol 13- acetate) and interleukin-4 (IL-4) inhibit apoptosis of B-CLL lymphocytes ex vivo. We used specific inhibitors of protein kinase C (PKC), extracellular-regulated kinase (ERK), and phosphatidylinositol 3–kinase (PI3-kinase) to study their involvement in TPA- and IL-4–induced survival of B-CLL lymphocytes. BisI, a specific inhibitor of PKC, induced apoptosis and inhibited the antiapoptotic activity of TPA and IL-4. B-CLL cells have a basal PKC activity that was increased by TPA but not by IL-4. TPA, but not IL-4, induced ERK activation. However, the inhibition of ERK activation did not affect the viability of B-CLL lymphocytes, demonstrating that this pathway is not involved in their survival. Inhibition of PI3-kinase by LY294002 induced apoptosis of B-CLL cells and inhibited the survival effect of IL-4 and TPA. In addition, Akt, a downstream effector of PI3-kinase activity, was phosphorylated by TPA and IL-4 in B-CLL cells, though PI3-kinase had no effect on PKC-dependent phosphorylation of Akt. Furthermore, the inhibition of PKC or PI3-kinase increased dexamethasone- and fludarabine-induced apoptosis ex vivo in the presence of survival factors. These results demonstrate that PKC and PI3-kinase are involved in the survival of B-CLL cells and suggest that inhibitors of these pathways could be combined with the drugs used in the treatment of B-CLL.
High frequency of leukemic clones in newborn screening blood samples of children with B-precursor acute lymphoblastic leukemia
Authors: Taub Jeffrey W. , Konrad Mark A. , Ge Yubin , Naber John M. , Scott Jackie S. , Matherly Larry H. , Ravindranath Yaddanapudi
Published: October 2002

The detection of leukemia cells on newborn genetic screening cards (“Guthrie cards”) of a small group of patients and several sets of identical twins developing acute lymphoblastic leukemia (ALL) with identical phenotypic and chromosomal markers has provided evidence that childhood ALL cases may arise in utero. We conducted a retrospective study of a randomly selected group of childhood B-precursor ALL patients to determine the frequency of the presence of “leukemic” clones prenatally in ALL cases by testing newborn screening cards. The 17 ALL patients analyzed had a median age of 46 months (range, 18 months to 13 years) and had median presenting white blood cell (WBC) counts of 10 950/μL (range, 2900-70 300/μL) at diagnosis. A clonal rearrangement of the immunoglobulin heavy chain (IgH) gene was identified in diagnostic lymphoblasts and sequenced and patient-specific primers were used to amplify DNA from blood samples on the patient's newborn screening cards. Twelve of the 17 (71%) analyzed newborn cards had detectable IgH rearrangements amplified by seminested polymerase chain reaction. DNA sequencing confirmed that the IgH rearrangements detected matched the IgH sequences identified from diagnostic leukemia cells, indicating the presence of a “leukemic” clone at birth. There were no differences in age or presenting WBC counts between the cases with or without positive newborn screening cards. All 6 patients with hyperdiploid ALL had detectable “leukemic” clones on their cards. The results of our study support the notion that a high proportion of childhood B-precursor ALL cases arise in utero, although postnatal events are also important factors in leukemogenesis.
Distinct clinical outcomes for cytogenetic abnormalities evolving from aplastic anemia
Authors: Maciejewski Jaroslaw P. , Risitano Antonio , Sloand Elaine M. , Nunez Olga , Young Neal S.
Published: October 2002

A serious complication of aplastic anemia (AA) is its evolution to clonal hematologic diseases such as myelodysplasia (MDS) and leukemia, which is usually associated with the appearance of a cytogenetic abnormality in bone marrow cells. We present here an analysis of a cohort of 30 patients with otherwise typical AA in whom clonal karyotypic evolution was observed during frequent periodic marrow examinations. The actuarial risk for this complication has been estimated in other studies at around 15% at 5 years. Conversion from normal to abnormal karyotype occurred at a constant rate after initial diagnosis, with about 50% of cases developing within the first 30 months. Transient chromosomal abnormalities were infrequent. Clinically, AA patients with clonal cytogenetic patterns were heterogenous; a variety of karyotypic defects with numerical and structural abnormalities of chromosome 7 accounted for 40% of all cases followed by trisomy 8, structural and numerical abnormalities of chromosome 13, deletion of Y chromosome, and complex cytogenetic abnormalities. Unlike in primary MDS, aberrancies of chromosome 5 and 20 were infrequent. The clinical course depended on the specific abnormal cytogenetic pattern. Most deaths related to leukemic transformation occurred in patients with abnormalities of chromosome 7 or complex cytogenetic alterations or both. Evolution of chromosome 7 abnormalities was seen most often in refractory patients who had failed to respond to therapy. In contrast, trisomy 8 developed in patients with good hematologic responses who often required chronic immunosuppression with cyclosporine A (CsA), and survival was excellent. Although AA patients with monosomy 7 showed a similar prognosis to those with primary MDS, trisomy 8 in AA appears to have a more favorable prognosis than in MDS.
Human T-cell lymphotropic virus type 1–transformed cells induce angiogenesis and establish functional gap junctions with endothelial cells
Authors: El-Sabban Marwan E. , Merhi Raghida Abou , Haidar Hounaida Abi , Arnulf Bertrand , Khoury Hilda , Basbous Jihane , Nijmeh Julie , de Thé Hugues , Hermine Olivier , Bazarbachi Ali
Published: October 2002

The role of angiogenesis in the growth and metastasis of solid tumors is well established. However, the role of angiogenesis in hematologic malignancies was only recently appreciated. We show that HTLV-I–transformed T cells, but not HTLV-I–negative CD4+T cells, secrete biologically active forms of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and, accordingly, induce angiogenesis in vitro. Furthermore, fresh ATL leukemic cells derived from patients with acute ATL produce VEGF and bFGF transcripts and proteins. The viral transactivator Tax activates the VEGF promoter, linking the induction of angiogenesis to viral gene expression. Angiogenesis is associated with the adhesion of HTLV-I–transformed cells to endothelial cells and gap junction–mediated heterocellular communication between the 2 cell types. Angiogenesis, cell adhesion, and communication likely contribute to the development of adult T-cell leukemia–lymphoma and represent potential therapeutic targets.