Regression of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue type after eradication of Helicobacter pylori

Certain features of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue (MALT) suggest the tumour is antigen-responsive. Given the close association between gastric MALT lymphoma and Helicobacter pylori, these organisms might be evoking the immunological response, and eradication of H pylori might inhibit the tumour. 6 patients in whom biopsies showed histological and molecular-genetic evidence of low-grade gastric B-cell MALT lymphoma with H pylori infection were treated with antibiotics. In all cases H pylori was eradicated and in 5, repeated biopsies showed no evidence of lymphoma. These results suggest that eradication of H pylori causes regression of low-grade B-cell gastric MALT lymphoma, and that anti-H-pylori treatment should be given for this lymphoma.

LIFR beta and gp130 as heterodimerizing signal transducers of the tripartite CNTF receptor

The ciliary neurotrophic factor (CNTF) receptor complex is shown here to include the CNTF binding protein (CNTFR alpha) as well as the components of the leukemia inhibitory factor (LIF) receptor, LIFR beta (the LIF binding protein) and gp130 [the signal transducer of interleukin-6 (IL-6)]. Thus, the conversion of a bipartite LIF receptor into a tripartite CNTF receptor apparently occurs by the addition of the specificity-conferring element CNTFR alpha. Both CNTF and LIF trigger the association of initially separate receptor components, which in turn results in tyrosine phosphorylation of receptor subunits. Unlike the IL-6 receptor complex in which homodimerization of gp130 appears to be critical for signal initiation, signaling by the CNTF and LIF receptor complexes depends on the heterodimerization of gp130 with LIFR beta. Ligand-induced dimerization of signal-transducing receptor components, also seen with receptor tyrosine kinases, may provide a general mechanism for the transmission of a signal across the cell membrane.

Bcl10 is involved in t(1;14)(p22;q32) of MALT B cell lymphoma and mutated in multiple tumor types

MALT B cell lymphomas with t(1;14)(p22;q32) showed a recurrent breakpoint upstream of the promoter of a novel gene, Bcl10. Bcl10 is a cellular homolog of the equine herpesvirus-2 E10 gene: both contain an amino-terminal caspase recruitment domain (CARD) homologous to that found in several apoptotic molecules. Bcl10 and E10 activated NF-kappaB but caused apoptosis of 293 cells. Bcl10 expressed in a MALT lymphoma exhibited a frameshift mutation resulting in truncation distal to the CARD. Truncated Bcl10 activated NF-kappaB but did not induce apoptosis. Wild-type Bcl10 suppressed transformation, whereas mutant forms had lost this activity and displayed gain-of-function transforming activity. Similar mutations were detected in other tumor types, indicating that Bcl10 may be commonly involved in the pathogenesis of human malignancy.

Targeted disruption of Smad3 reveals an essential role in transforming growth factor beta-mediated signal transduction

The Smads are a family of nine related proteins which function as signaling intermediates for the transforming growth factor beta (TGF-beta) superfamily of ligands. To discern the in vivo functions of one of these Smads, Smad3, we generated mice harboring a targeted disruption of this gene. Smad3 null mice, although smaller than wild-type littermates, are viable, survive to adulthood, and exhibit an early phenotype of forelimb malformation. To study the cellular functions of Smad3, we generated Smad3 null mouse embryonic fibroblasts (MEFs) and dermal fibroblasts. We demonstrate that null MEFs have lost the ability to form Smad-containing DNA binding complexes and are unable to induce transcription from the TGF-beta-responsive promoter construct, p3TP-lux. Using the primary dermal fibroblasts, we also demonstrate that Smad3 is integral for induction of endogenous plasminogen activator inhibitor 1. We subsequently demonstrate that Smad3 null MEFs are partially resistant to TGF-beta's antiproliferative effect, thus firmly establishing a role for Smad3 in TGF-beta-mediated growth inhibition. We next examined cells in which Smad3 is most highly expressed, specifically cells of immune origin. Although no specific developmental defect was detected in the immune system of the Smad3 null mice, a functional defect was observed in the ability of TGF-beta to inhibit the proliferation of splenocytes activated by specific stimuli. In addition, primary splenocytes display defects in TGF-beta-mediated repression of cytokine production. These data, taken together, establish a role for Smad3 in mediating the antiproliferative effects of TGF-beta and implicate Smad3 as a potential effector for TGF-beta in modulating immune system function.

Neuronal deficits, not involving motor neurons, in mice lacking BDNF and/or NT4

Nerve growth factor and other neurotrophins signal to neurons through the Trk family of receptor tyrosine kinases. TrkB is relatively promiscuous in vitro, acting as a receptor for brain-derived neurotrophic factor (BDNF), neurotrophin-4 (NT4) and, to a lesser extent, NT3 (refs 3-5). Mice lacking TrkB show a more severe phenotype than mice lacking BDNF, suggesting that TrkB may act as a receptor for additional ligands in vivo. To explore this possibility, we generated mice lacking NT4 or BDNF as well as mice lacking both neurotrophins. Unlike mice lacking other Trks or neurotrophins, NT4-deficient mice are long-lived and show no obvious neurological defects. Analysis of mutant phenotypes revealed distinct neuronal populations with different neurotrophin requirements. Thus vestibular and trigeminal sensory neurons require BDNF but not NT4, whereas nodose-petrosal sensory neurons require both BDNF and NT4. Motor neurons, whose numbers are drastically reduced in mice lacking TrkB, are not affected even in mice lacking both BDNF and NT4. These results suggest that another ligand, perhaps NT3, does indeed act on TrkB in vivo.

Ephrin-B2 selectively marks arterial vessels and neovascularization sites in the adult, with expression in both endothelial and smooth-muscle cells

The Eph receptor tyrosine kinases and their membrane-tethered ephrin ligands provide critical guidance cues at points of cell-to-cell contact. It has recently been reported that the ephrin-B2 ligand is a molecular marker for the arterial endothelium at the earliest stages of embryonic angiogenesis, while its receptor EphB4 reciprocally marks the venous endothelium. These findings suggested that ephrin-B2 and EphB4 are involved in establishing arterial versus venous identity and perhaps in anastamosing arterial and venous vessels at their junctions. By using a genetically engineered mouse in which the lacZ coding region substitutes and reports for the ephrin-B2 coding region, we demonstrate that ephrin-B2 expression continues to selectively mark arteries during later embryonic development as well as in the adult. However, as development proceeds, we find that ephrin-B2 expression progressively extends from the arterial endothelium to surrounding smooth muscle cells and to pericytes, suggesting that ephrin-B2 may play an important role during formation of the arterial muscle wall. Furthermore, although ephrin-B2 expression patterns vary in different vascular beds, it can extend into capillaries about midway between terminal arterioles and postcapillary venules, challenging the classical conception that capillaries have neither arterial nor venous identity. In adult settings of angiogenesis, as in tumors or in the female reproductive system, the endothelium of a subset of new vessels strongly expresses ephrin-B2, once again contrary to earlier views that such new vessels lack arterial/venous characteristics and derive from postcapillary venules. While earlier studies had focused on a role for ephrin-B2 during the earliest embryonic stages of arterial/venous determination, our current findings using ephrin-B2 as an arterial marker in the adult challenge prevailing views of the arterial/venous identity of quiescent as well as remodeling adult microvessels and also highlight a possible role for ephrin-B2 in the formation of the arterial muscle wall.

Differential roles of IL-1 and TNF-alpha on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.

Detection of monoclonality in low-grade B-cell lymphomas using the polymerase chain reaction is dependent on primer selection and lymphoma type

Detection of B-cell monoclonality using the polymerase chain reaction (PCR) promises the quick and cost-effective separation of monoclonal from polyclonal B-cell disease. However, the efficiency of the method has yet to be fully assessed, particularly with regard to disease type and selection of PCR primers. We have evaluated two approaches based on amplification of the immunoglobulin heavy chain gene using framework 2 (Fr2) and framework 3 (Fr3) region primers. Frozen tissue samples from 94 cases of low-grade B-cell lymphoma were investigated, all of which had previously been shown to be monoclonal by Southern blot analysis. Using a Fr2 primer, we were able to show monoclonality in 85 per cent of cases; with Fr3, 80 per cent of cases; and using both techniques in separate reactions, 90 per cent of cases. Thus, a significant false-negative rate exists with either primer which can be reduced by using both. We also found a difference in the efficiency of detection in different types of lymphoma; only 87 per cent of mucosa-associated lymphomas and centroblastic/centrocytic lymphomas were shown to be monoclonal, whereas all of the other lymphoma types tested were positive using one or both methods. We conclude that PCR detection of B-cell monoclonality allows rapid analysis of tissue samples, including paraffin-processed material. False-negative results which occur in some types of lymphoma can be reduced by the use of two or more primer combinations.

Ephrin-B3 is the midline barrier that prevents corticospinal tract axons from recrossing, allowing for unilateral motor control

Growing axons follow highly stereotypical pathways, guided by a variety of attractive and repulsive cues, before establishing specific connections with distant targets. A particularly well-known example that illustrates the complexity of axonal migration pathways involves the axonal projections of motor neurons located in the motor cortex. These projections take a complex route during which they first cross the midline, then form the corticospinal tract, and ultimately connect with motor neurons in the contralateral side of the spinal cord. These obligatory contralateral connections account for why one side of the brain controls movement on the opposing side of the body. The netrins and slits provide well-known midline signals that regulate axonal crossings at the midline. Herein we report that a member of the ephrin family, ephrin-B3, also plays a key role at the midline to regulate axonal crossing. In particular, we show that ephrin-B3 acts as the midline barrier that prevents corticospinal tract projections from recrossing when they enter the spinal gray matter. We report that in ephrin-B3(-/-) mice, corticospinal tract projections freely recross in the spinal gray matter, such that the motor cortex on one side of the brain now provides bilateral input to the spinal cord. This neuroanatomical abnormality in ephrin-B3(-/-) mice correlates with loss of unilateral motor control, yielding mice that simultaneously move their right and left limbs and thus have a peculiar hopping gait quite unlike the alternate step gait displayed by normal mice. The corticospinal and walking defects in ephrin-B3(-/-) mice resemble those recently reported for mice lacking the EphA4 receptor, which binds ephrin-B3 as well as other ephrins, suggesting that the binding of EphA4-bearing axonal processes to ephrin-B3 at the midline provides the repulsive signal that prevents corticospinal tract projections from recrossing the midline in the developing spinal cord.

The adipose tissue phenotype of hormone-sensitive lipase deficiency in mice

OBJECTIVE

To directly ascertain the physiological roles in adipocytes of hormone-sensitive lipase (HSL; E.C. 3.1.1.3), a multifunctional hydrolase that can mediate triacylglycerol cleavage in adipocytes.

RESEARCH METHODS AND PROCEDURES

We performed constitutive gene targeting of the mouse HSL gene (Lipe), subsequently studied the adipose tissue phenotype clinically and histologically, and measured lipolysis in isolated adipocytes.

RESULTS

Homozygous HSL-/- mice have no detectable HSL peptide or cholesteryl esterase activity in adipose tissue, and heterozygous mice have intermediate levels with respect to wild-type and deficient littermates. HSL-deficient mice have normal body weight but reduced abdominal fat mass compared with normal littermates. Histologically, both white and brown adipose tissues in HSL-/- mice show marked heterogeneity in cell size, with markedly enlarged adipocytes juxtaposed to cells of normal morphology. In isolated HSL-/- adipocytes, lipolysis is not significantly increased by beta3-adrenergic stimulation, but under basal conditions in the absence of added catecholamines, the lipolytic rate of isolated HSL-/- adipocytes is at least as high as that of cells from normal controls. Cold tolerance during a 48-hour period at 4 degrees C was similar in HSL-/- mice and controls. Overnight fasting was well-tolerated clinically by HSL-/- mice, but after fasting, liver triglyceride content was significantly lower in HSL-/- mice compared with wild-type controls.

CONCLUSIONS

In isolated fat cells, the lipolytic rate after beta-adrenergic stimulation is mainly dependent on HSL. However, the observation of a normal rate of lipolysis in unstimulated HSL-/- adipocytes suggests that HSL-independent lipolytic pathway(s) exist in fat. Physiologically, HSL deficiency in mice has a modest effect under normal fed conditions and is compatible with normal maintenance of core body temperature during cold stress. However, the lipolytic response to overnight fasting is subnormal.

Stat protein transactivation domains recruit p300/CBP through widely divergent sequences

The signal transduction and activator of transcription (Stat) gene family has been highly conserved throughout evolution. Gene duplication and divergence has produced 7 mammalian Stat genes, each of which mediates a distinct process. While some Stat proteins are activated by multiple cytokines, Stat2 is highly specific for responses to type I interferon. We have cloned mouse Stat2 and found that while its sequence was more divergent from its human homologue than any other mouse-human Stat pairs, it was fully functional even in human cells. Overall sequence identity was only 69%, compared with 85-99% similarity for other Stat genes, and several individual domains that still served similar or identical functions in both species were even less well conserved. The coiled-coil domain responsible for interaction with IRF9 was only 65% identical and yet mouse Stat2 interacted with either human or mouse IRF9; the carboxyl terminus was only 30% identical and yet both regions functioned as equal transactivation domains. Both mouse and human transactivation domains recruited the p300/CBP coactivator and were equally sensitive to inhibition by adenovirus E1A protein. Interestingly, the Stat3 carboxyl terminus also functioned as a transactivator capable of recruiting p300/CBP, as does the Stat1 protein, although with widely differing potencies. Yet these proteins share no sequence similarity with Stat2. These data demonstrate that highly diverged primary sequences can serve similar or identical functions, and that the minimal regions of similarity between human and mouse Stat2 may define the critical determinants for function.

The effect of pH on the dimensionality of coordination polymers

Hydrothermal reactions of simple alkaline salts or their hydroxides with 3,5-pyrazoledicarboxylic acid (H(3)pdc) yielded seven new compounds. At a lower pH level three one-dimensional structures [Ca(Hpdc)(H(2)O)(4)].2H(2)O (1), [Ca(Hpdc)(H(2)O)(4)].H(2)O (2), and [Ba(H(2)pdc)(2)(H(2)O)(4)].2H(2)O (6) were obtained by evaporation of the solutions resulting from hydro(solvo)thermal reactions of MCl(2) (M = Ca, Ba) with H(3)pdc in water (1, 6) or in water/Et(3)N (2) at 150 degrees C for 3 days. Crystal structures of 1 and 2 contain zigzag chains of metal centers bridged by a single Hpdc(2-) ligand, whereas structure 6 consists of linear chains of metal centers bridged by two H(2)pdc(-) ligands. A dimer molecule [Sr(H(3)pdc)(H(2)pdc)(2)(H(2)O)(3)](2).2(H(3)pdc).4H(2)O (4) was obtained from a similar hydrothermal reaction using Sr(ClO(4))(2).6H(2)O instead of MCl(2). This compound contains [2+2] metallomacrocycles. At higher pH levels (pH = 4-6), the three-dimensional polymers [M(Hpdc)(H(2)O)] (Ca 3, Sr 5, Ba 7 ) were isolated by reactions of MCl(2) (M = Ca, Sr, Ba) with H(3)pdc in water/Et(3)N or in M(OH)(2) (M = Ca, Sr, Ba) with H(3)pdc in water under hydro(solvo)thermal conditions (150 degrees C, 3 days). Calcium and strontium are seven- and nine-coordinated in 3 and 5, respectively; barium is nine- and ten-coordinated in 7. It was observed that the increase in pH resulted in a higher connectivity level of ligands, which in turn leads to a higher dimensionality of the crystal structures. The correlation between the structures and pH values will be discussed. Crystal data: for 1, monoclinic, space group P2(1)/n (No. 14), with a = 8.382(2), b = 12.621(3), c = 11.767(2) A, beta = 98.91(3) degrees, Z = 4; for 2, 3, and 5, monoclinic, space group P2(1)/c (No. 14), Z = 4, a = 7.711(2), b = 15.574(3), c = 9.341(2) A, beta = 96.73(3) degrees, Z = 4 (2), a = 6.616(1), b = 12.654(3), c = 8.782(2) A, beta = 103.65(3) degrees, Z = 4 (3), a = 9.213(2), b = 12.088(3), c = 6.196(2) A, beta = 98.96(3) degrees (5); for 4 and 7, triclinic, space group P1 (No. 2), with a = 11.263(2), b = 11.460(3), c = 12.904(2) A, alpha = 71.54(3), beta = 98.96(3), gamma = 89.03(3) degrees, Z = 1 (4), a = 7.107(1), b = 9.780(2), c = 11.431(2) A, alpha = 74.69(3), beta = 73.39(3), gamma = 85.29(3) degrees, Z = 2 (7); for 6, monoclinic, space group C2/c (No. 15), with a = 20.493(4), b = 6.708(1), c = 15.939(3) A, beta = 123.56(3) degrees, Z = 4.

The immunopathophysiology of acute graft-versus-host-disease

The major complication after allogeneic bone marrow transplantation (BMT) is the development of graft-versus-host-disease (GVHD). This disease is initiated during the conditioning of the recipient, when host tissues are damaged. During the afferent phase of the disease, alloreactive donor T cells recognize foreign major and minor histocompatibility antigens of host tissues. The efferent phase includes activation of inflammatory effector cells as well as the secretion of cytopathic molecules which induce pathology in skin, gastrointestinal tract, liver, lung, and the immune system. Substantial experimental and clinical evidence now indicates a central role of cytokines in the immunopathophysiology of acute GVHD, which forms the basis of this review. The balance between cytokines released by T helper 1 (Th1) cells (interleukin 2, interferon-gamma) or by T helper 2 (Th2) cells (interleukin 4, interleukin 10) after allogeneic BMT is hypothesized to govern the extent of the systemic inflammatory response. Because Th2 cytokines can inhibit the production of proinflammatory cytokines such as interleukin 1 and tumor necrosis factor-alpha, a Th1-->Th2 shift in the initial response of donor T cells may interrupt the cytokine cascade and thus offer a new approach to the prevention and treatment of acute GVHD. Successful interventions to modify the response of donor T cells may obviate the need for T cell depletion and thereby avoid the increased risk of relapse of malignancy and impairment of donor cell engraftment.

IL-11 separates graft-versus-leukemia effects from graft-versus-host disease after bone marrow transplantation

We recently showed that IL-11 prevents lethal graft-versus-host disease (GVHD) in a murine bone marrow transplantation (BMT) model of GVHD directed against MHC and minor antigens. In this study, we have investigated whether IL-11 can maintain a graft-versus-leukemia (GVL) effect. Lethally irradiated B6D2F1 mice were transplanted with either T cell-depleted (TCD) bone marrow (BM) alone or with BM and splenic T cells from allogeneic B6 donors. Animals also received host-type P815 mastocytoma cells at the time of BMT. Recipients were injected subcutaneously with recombinant human IL-11 or control diluent twice daily, from 2 days before BMT to 7 days after BMT. TCD recipients all died from leukemia by day 23. All control- and IL-11-treated allogeneic animals effectively rejected their leukemia, but IL-11 also reduced GVHD-related mortality. Examination of the cellular mechanisms of GVL and GVHD in this system showed that IL-11 selectively inhibited CD4-mediated GVHD, while retaining both CD4- and CD8-mediated GVL. In addition, IL-11 treatment did not affect cytolytic effector functions of T cells after BMT either in vivo or in vitro. Studies with perforin-deficient donor T cells demonstrated that the GVL effect was perforin dependent. These data demonstrated that IL-11 can significantly reduce CD4-dependent GVHD without impairing cytolytic function or subsequent GVL activity of CD8(+) T cells. Brief treatment with IL-11 shortly after BMT may therefore represent a novel strategy for separating GVHD and GVL.

Rheology of human blood plasma: viscoelastic versus Newtonian behavior

We investigate the rheological characteristics of human blood plasma in shear and elongational flows. While we can confirm a Newtonian behavior in shear flow within experimental resolution, we find a viscoelastic behavior of blood plasma in the pure extensional flow of a capillary breakup rheometer. The influence of the viscoelasticity of blood plasma on capillary blood flow is tested in a microfluidic device with a contraction-expansion geometry. Differential pressure measurements revealed that the plasma has a pronounced flow resistance compared to that of pure water. Supplementary measurements indicate that the viscoelasticity of the plasma might even lead to viscoelastic instabilities under certain conditions. Our findings show that the viscoelastic properties of plasma should not be ignored in future studies on blood flow.

Impaired immune responses and B-cell proliferation in mice lacking the Id3 gene

B-lymphocyte activation and proliferation induced by the B-cell receptor (BCR) signals are important steps in the initiation of humoral immune responses. How the BCR signals are translated by nuclear transcription factors into cell cycle progression is poorly understood. Id3 is an immediate-early gene responding to growth and mitogenic signals in many cell types including B cells. The primary function of the Id3 protein has been defined as that of inhibitor of basic-helix-loop-helix (bHLH) transcription factors. The interaction between Id3 and bHLH proteins, many of which are essential for cellular differentiation, has been proposed as a key regulatory event leading to cellular proliferation instead of differentiation. To further investigate the role of Id3 in tissue and embryo development and the mechanism of Id3-mediated growth regulation, we generated and analyzed Id3-deficient mice. While these mice display no overt abnormality in tissue and embryo development, their humoral immunity is compromised. The amounts of immunoglobulins produced in Id3-deficient mice immunized with a T-cell-dependent antigen and a type 2 T-cell-independent antigen are attenuated and severely impaired, respectively. Further analysis of lymphocytes isolated from Id3-deficient mice reveals a B-cell defect in their proliferation response to BCR cross-linking but not to lipopolysaccharide or a combination of BCR cross-linking and interleukin-4. Analyses of cultured lymphocytes also suggest involvement of Id3 in cytokine production in T cells and isotype switching in B cells. Finally, the proliferation defect in Id3-deficient B cells can be rescued by ectopic expression of Id1, a homologue of Id3. Taken together, these results define a necessary and specific role for Id3 in mediating signals from BCR to cell cycle progression during humoral immune responses.

Neurotrophic factor receptors and their signal transduction capabilities in rat astrocytes

Until recently, astrocytes were not considered as sites for neurotrophic factor action. We show here that, both in vivo and in vitro, astrocytes express receptors for two separate families of neurotrophic factors. In the intact adult rat CNS, astrocytes express the extracellular domain of the neurotrophin receptor TrkB and, in a more restricted population, the low-affinity nerve growth factor receptor p75LNGFR. In the lesioned CNS, expression of the alpha component of the receptor for ciliary neurotrophic factor (CNTFR alpha) switches from a purely neuronal localization to cells in the glial scar at the edge of the wound. Using cultured hippocampal astrocytes as a model to address the functional status of these receptors, we have found only the truncated forms of TrkB and TrkC, which are incapable of signal transduction as measured by protein tyrosine phosphorylation or immediate early gene induction. In contrast, a fully functional CNTF receptor complex capable of signal transduction is present on cultured astrocytes. Thus, the neurotrophin receptors may act primarily to sequester or present the neurotrophins, whereas in the case of CNTF a functional response can be initiated within the astrocyte.

Novel silver(I)-organic coordination polymers: conversion of extended structures in the solid state as driven by argentophilic interactions

Structurally distinct coordination polymers [Ag(bpp)]ClO4 1 and [Ag(bpp)]PF6 2 [bpp = 1,3-bis(4-pyridyl)propane] have been assembled; the conversion of 1 into 2 on treatment with NaPF6 is driven by argentophilic interactions and is the first such transformation reported for silver(I)-organic coordination polymers.

Evolutionally conserved plant homologue of the Bax inhibitor-1 (BI-1) gene capable of suppressing Bax-induced cell death in yeast(1)

The plant homologue of Bax Inhibitor-1, a gene described to suppress the cell death induced by Bax gene expression in yeast, was isolated from Oryza sativa L. (rice) and Arabidopsis. The amino acid sequence of the predicted protein was well conserved in both animal and plant (45% in amino acids) and contained six or seven membrane-spanning segments. Northern blot analysis showed that OsBI-1 transcripts were present in all tissues examined. The OsBI-1 cDNA suppressed cell death induced by mammalian Bax in yeast, suggesting functional conservation of this BI-1 homologue in the plant kingdom.

Sources of DNA for detecting B cell monoclonality using PCR

AIMS

To evaluate the polymerase chain reaction (PCR) demonstration of clonal immunoglobulin heavy chain gene rearrangements using routinely prepared, unstained, and stained formalin fixed, paraffin wax embedded tissue samples.

METHODS

Extracts from (a) fresh frozen tissue samples, (b) unstained, and (c) haematoxylin and eosin stained formalin fixed, paraffin wax embedded 5 microns tissue sections from 42 cases of low grade B cell lymphoma, all shown to be monoclonal by Southern blot analysis, were analysed using PCR. Two regions of the variable segment of the immunoglobulin heavy chain gene were amplified (framework 2 to joining region [Fr2/JH] and framework 3 to joining region [Fr3/JH]). Twelve samples of reactive lymphoid tissue were studied as controls. Products from each case were directly compared on polyacrylamide gels.

RESULTS

Using both primer combinations, monoclonality was detected in 38 of 42 (90%) cases using fresh material, 37 of 42 (88%) using unstained paraffin wax embedded samples, and in 35 of 42 (83%) cases using haematoxylin and eosin stained sections. No false positive results attributable to fixation, processing, or staining were identified, although the efficiency of amplification using the Fr2/JH primers was significantly reduced.

CONCLUSIONS

PCR determination of B cell clonality using paraffin wax embedded material is sufficiently sensitive and reliable for use as a routine diagnostic adjunct to conventional morphological and immunocytochemical assessment of lymphoproliferative disease.

Reactions and reactivity of Co-bpdc coordination polymers (bpdc = 4,4'-biphenyldicarboxylate)

By choosing a suitable metal center, ligand, and solvents, we have revealed several structural transformations involving a polymer precursor. infinity 1[Co(bpdc)(H2O)2].H2O (1) was prepared by reaction of Na2bpdc and Co(NO3)2 in aqueous solution. Immersing 1 in pyridine/water solutions of (2:1) and (8:1) ratios yielded a second one-dimensional structure infinity 1[Co(bpdc)(py)2(H2O)2].2py (2) and a two-dimensional structure infinity 2[Co(bpdc)(py)2].H2O (3), respectively. After heating 1 under N2 to remove all water within the structure, the compound Co(bpdc) (IR) was obtained. When IR was immersed in solutions of pyridine/water (5:4) and in pure pyridine (in air), a third one-dimensional structure of infinity 1[Co(bpdc)(py)2(H2O)2].2py.H2O (4) and 3, respectively, were obtained. Compounds 2-4 easily transformed to 1 when immersed in water. Crystal data for 1: monoclinic, space group C2/c with a = 6.950(1), b = 31.585(6), and c = 6.226(1) A, beta = 95.84(3) degrees, Z = 4. Crystal data for 2: triclinic, space group P1 with a = 9.646(2), b = 10.352(2), and c = 17.031(3) A, alpha = 79.02(3) degrees, beta = 86.88(3) degrees, gamma = 77.16(3) degrees, Z = 2. Crystal data for 3: triclinic, space group P1 with a = 9.137(2), b = 10.480(2), and c = 12.254(2) A, alpha = 102.10(3) degrees, beta = 100.80(3) degrees, gamma = 99.43(3) degrees, Z = 2. Crystal data for 4: orthorhombic, space group Pbcn with a = 13.468(3), b = 16.652 (3), and c = 14.977(3) A, Z = 4.

Critical roles of a cyclic AMP responsive element and an E-box in regulation of mouse renin gene expression

Mouse As4.1 cells, obtained after transgene-targeted oncogenesis to induce neoplasia in renal renin expressing cells, express high levels of renin mRNA from their endogenous Ren-1(c) gene. We have previously identified a 242-base pair enhancer (coordinates -2866 to -2625 relative to the CAP site) upstream of the mouse Ren-1(c) gene. This enhancer, in combination with the proximal promoter (-117 to +6), activates transcription nearly 2 orders of magnitude in an orientation independent fashion. To further delimit sequences necessary for transcriptional activation, renin promoter-luciferase reporter gene constructs containing selected regions of the Ren-1(c) enhancer were analyzed after transfection into As4.1 cells. These results demonstrate that several regions are required for full enhancer activity. Sequences from -2699 to -2672, which are critical for the enhancer activity, contain a cyclic AMP responsive element (CRE) and an E-box. Electrophoretic mobility shift assays demonstrated that transcription factors CREB/CREM and USF1/USF2 in As4.1 cell nuclear extracts bind to oligonucleotides containing the Ren-1(c) CRE and E-box, respectively. These two elements are capable of synergistically activating transcription from the Ren-1(c) promoter. Moreover, mutation of either the CRE or E-box results in almost complete loss of enhancer activity, suggesting the critical roles these two elements play in regulating mouse Ren-1(c) gene expression. Although the Ren-1(c) gene contains a CRE, its expression is not induced by cAMP in As4.1 cells. This appears to reflect constitutive activation of protein kinase A in As4.1 cells since treatment with the protein kinase A inhibitor, H-89, caused a significant reduction in Ren-1(c) gene expression and this reduction is mediated through the CRE at -2699 to -2688.

Possible dominant-negative mutation of the SHIP gene in acute myeloid leukemia

The SH2 domain-containing inositol 5'-phosphatase (SHIP) is crucial in hematopoietic development. To evaluate the possible tumor suppressor role of the SHIP gene in myeloid leukemogenesis, we examined primary leukemia cells from 30 acute myeloid leukemia (AML) patients, together with eight myeloid leukemia cell lines. A somatic mutation at codon 684, replacing Val with Glu, was detected in one patient, lying within the signature motif 2, which is the phosphatase active site. The results of an in vitro inositol 5'-phosphatase assay revealed that the mutation reduced catalytic activity of SHIP. Leukemia cells with the mutation showed enhanced Akt phosphorylation following IL-3 stimulation. K562 cells transfected with the mutated SHIP-V684E cDNA showed a growth advantage even at lower serum concentrations and resistance to apoptosis induced by serum deprivation and exposure to etoposide. These results suggest a possible role of the mutated SHIP gene in the development of acute leukemia and chemotherapy resistance through the deregulation of the phosphatidylinositol-3,4,5-triphosphate (PI(3,4,5)P3)/Akt signaling pathway. This is the first report of a mutation in the SHIP gene in any given human cancer, and indicates the need for more attention to be paid to this gene with respect to cancer pathogenesis.

Evaluation of a single-pass intestinal-perfusion method in rat for the prediction of absorption in man

Prediction of the fraction of dose absorbed from the intestine (Fa) in man is essential in the early drug discovery stage. In-vitro assays in Caco-2 and MDCK cells are routinely used for that purpose, and their predictive value has been reported. However, in-situ techniques might provide a more accurate estimation of Fa. In this study, we evaluated a single-pass intestinal-perfusion (SPIP) method in the rat for its use in the prediction of absorption in man and compared it with a previous report using cell-based assays. Effective permeability coefficients (Peff) were determined in rats for 14 compounds, and ranged from 0.043x 10(-4) cm s(-1) to 1.67 x 10(-4) cm s(-1). These values strongly correlated (r2 = 0.88) with reported Peff values for man. In addition, the Spearman rank correlation coefficient calculated for in-situ-derived Peff and absorption in man was 0.92 while for the previously tested in-vitro Caco-2 and MDCK systems vs absorption in man, the correlation coefficients were 0.61 and 0.59, respectively. SPIP provided a better prediction of human absorption than the cell-based assays. This method, although time consuming, could be used as a secondary test for studying the mechanisms governing the absorption of new compounds, and for predicting more accurately the fraction absorbed in man.