Consistent pseudopotential interactions in lattice Boltzmann models

We outline a systematic procedure on how to construct and derive interactions for nonideal lattice fluids. Using a mesoscopic approach based on exact lattice theories, we prove the consistency of the resulting diffuse interface theory with continuum thermodynamics. Translated in the framework of the so called "Shan-Chen" model for nonideal lattice fluids, this paper shows how to adjust the associated pseudopotentials to reproduce a free energy model based on a square gradient theory of equilibrium interfaces.

Coupling of V(D)J recombination to the cell cycle suppresses genomic instability and lymphoid tumorigenesis

V(D)J gene segment recombination is linked to the cell cycle by the periodic phosphorylation and destruction of the RAG-2 protein at the G1-to-S cell cycle transition. To examine the function of this coupling, we constructed mice in which the phosphorylation site at threonine 490 of RAG-2 was mutated to alanine. The RAG-2(T490A) mutation uncoupled DNA cleavage from cell cycle and promoted aberrant recombination. Similar aberrant recombination products were observed in mice deficient in the Skp2 ubiquitin ligase subunit, which is required for periodic destruction of RAG-2. On a p53-deficient background, the RAG-2(T490A) mutation induced lymphoid malignancies characterized by clonal chromosomal translocations involving antigen receptor genes. Taken together, these observations provide a direct link between the periodic destruction of RAG-2 and lymphoid tumorigenesis. We infer that cell cycle control of the V(D)J recombinase limits the potential genomic damage that could otherwise result from RAG-mediated DNA cleavage.

Interferon-gamma-dependent infiltration of human T cells into neuroblastoma tumors in vivo

PURPOSE

To investigate the impact of interferon-gamma-mediated upregulation of major histocompatibility complex class I expression on tumor-specific T-cell cytotoxicity and T-cell trafficking into neuroblastoma tumors in vivo.

EXPERIMENTAL DESIGN

Restoration of major histocompatibility complex class I expression by interferon-gamma treatment enhances killing of neuroblastoma cells. To understand the potential of this approach in vivo, we developed a novel model of neuroblastoma in which NOD/scid/IL2R gamma(null) immunodeficient mice are engrafted with both human T cells and tumor cells.

RESULTS

Here, we show enhanced killing of neuroblastoma cells by patient-derived, tumor-specific T cells in vitro. In addition, interferon-gamma treatment in vivo induces efficient upregulation of major histocompatibility complex class I expression on neuroblastoma tumor cells, and this is accompanied by significantly enhanced infiltration of T cells into the tumor. In a pilot clinical trial in patients with high-risk neuroblastoma, we similarly observed augmented T-cell trafficking into neuroblastoma nests in tumor biopsy specimens obtained from patients after 5 days of systemic interferon-gamma therapy.

CONCLUSIONS

Interferon-gamma overcomes critical obstacles to the killing of human neuroblastoma cells by specific T cells. Together, these findings provide a rationale for the further testing of interferon-gamma as an approach for improving the efficacy of T cell-based therapies for neuroblastoma and other major histocompatibility complex class I-deficient malignancies. In addition, we describe a model that may expedite the preclinical screening of approaches aimed at augmenting T-cell trafficking into human tumors.

Identification of a novel HLA-DRB allele, HLA-DRB1*1461

We describe the identification of a new DRB1*14 allele, DRB1*1461, found in a Chinese individual. The novel allele has been identified in routine polymerase chain reaction-sequence-specific oligonucleotide and sequence-based typing. The nucleotide sequence of DRB1*1461 is identical to DRB1*1404 except for a single substitution in codon 16 (TAT-->CAT), leading to a change from Tyr to His.

A novel allele, HLA-A*0128, identified by sequence-based typing in a Chinese individual

In this report, we describe the identification of a novel allele HLA-A*0128, which was found in a registered donor from China Marrow Donor Program. The A*0128 allele differs from the A*0113 by one nucleotide substitutions in exon 2 at position 282 (G-->C). The mutation results in a codon change: at codon 70 where a glutamine acid is substituted by a histidine acid.

Distinct effects of IL-18 on the engraftment and function of human effector CD8 T cells and regulatory T cells

IL-18 has pleotropic effects on the activation of T cells during antigen presentation. We investigated the effects of human IL-18 on the engraftment and function of human T cell subsets in xenograft mouse models. IL-18 enhanced the engraftment of human CD8⁺ effector T cells and promoted the development of xenogeneic graft versus host disease (GVHD). In marked contrast, IL-18 had reciprocal effects on the engraftment of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) in the xenografted mice. Adoptive transfer experiments indicated that IL-18 prevented the suppressive effects of Tregs on the development of xenogeneic GVHD. The IL-18 results were robust as they were observed in two different mouse strains. In addition, the effects of IL-18 were systemic as IL-18 promoted engraftment and persistence of human effector T cells and decreased Tregs in peripheral blood, peritoneal cavity, spleen and liver. In vitro experiments indicated that the expression of the IL-18Rα was induced on both CD4 and CD8 effector T cells and Tregs, and that the duration of expression was less sustained on Tregs. These preclinical data suggest that human IL-18 may have use as an adjuvant for immune reconstitution after cytotoxic therapies, and to augment adoptive immunotherapy, donor leukocyte infusions, and vaccine strategies.

CD28 costimulation is essential for human T regulatory expansion and function

The costimulatory requirements required for peripheral blood T regulatory cells (Tregs) are unclear. Using cell-based artificial APCs we found that CD28 but not ICOS, OX40, 4-1BB, CD27, or CD40 ligand costimulation maintained high levels of Foxp3 expression and in vitro suppressive function. Only CD28 costimulation in the presence of rapamycin consistently generated Tregs that consistently suppressed xenogeneic graft-vs-host disease in immunodeficient mice. Restimulation of Tregs after 8-12 days of culture with CD28 costimulation in the presence of rapamycin resulted in >1000-fold expansion of Tregs in <3 wk. Next, we determined whether other costimulatory pathways could augment the replicative potential of CD28-costimulated Tregs. We observed that while OX40 costimulation augmented the proliferative capacity of CD28-costimulated Tregs, Foxp3 expression and suppressive function were diminished. These studies indicate that the costimulatory requirements for expanding Tregs differ from those for T effector cells and, furthermore, they extend findings from mouse Tregs to demonstrate that human postthymic Tregs require CD28 costimulation to expand and maintain potent suppressive function in vivo.

Identification of a novel HLA-B allele, HLA-B*3713, in a Chinese individual

A novel human leukocyte antigen (HLA) class I allele, HLA-B*3713, has been identified in a Chinese individual. The HLA-B*3713 allele differs from the closest matching allele B*370101 by one nucleotide substitutions in exon 3 at nt 527(T-->A), resulting in an amino acid change from Val (GTG) to Glu (GAG) at codon 152.

Identification of 11 novel HLA alleles found during typing of unrelated registry donors in China

Eleven novel human leukocyte antigen (HLA) alleles were identified during routine sequence-specific oligonucleotide probe (SSOP) typing (LABType; One Lambda Inc., Los Angeles, CA) of volunteers for a hematopoietic stem cell registry in Beijing, China. The new alleles were detected when one or more probes gave an unexpected reactivity pattern.

Lattice Boltzmann models for nonideal fluids with arrested phase-separation

The effects of midrange repulsion in lattice Boltzmann models on the coalescence and/or breakup behavior of single-component, nonideal fluids are investigated. It is found that midrange repulsive interactions allow the formation of spraylike, multidroplet configurations, with droplet size directly related to the strength of the repulsive interaction. The simulations show that just a tiny 10% of midrange repulsive pseudoenergy can boost the surface:volume ratio of the phase-separated fluid by nearly two orders of magnitude. Drawing upon a formal analogy with magnetic Ising systems, a pseudopotential energy is defined, which is found to behave similar to a quasiconserved quantity for most of the time evolution. This offers a useful quantitative indicator of the stability of the various configurations, thus helping the task of their interpretation and classification. The present approach appears to be a promising tool for the computational modeling of complex flow phenomena, such as atomization, spray formation, microemulsions, breakup phenomena, and possibly glassylike systems as well.

Magnetic resonance microscopy and immunohistochemistry of the CNS of the mutant SOD murine model of ALS reveals widespread neural deficits

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that primarily affects motor neurons and descending motor tracts of the CNS. We have evaluated the CNS of a murine model of familial ALS based on the over-expression of mutant human superoxide dismutase (mSOD; G93A) using magnetic resonance microscopy (MRM) and immunohistochemistry (IHC). Three-dimensional volumetric analysis was performed from 3D T2*-weighted images acquired at 17.6 T at isotropic resolutions of 40 mum. Compared to controls, mSOD mice had significant reductions in the volumes of total brain, substantia nigra, striatum, hippocampus, and internal capsule, with decreased cortical thickness in primary motor and somatosensory cortices. In the spinal cord, mSOD mice had significantly decreased volume of both the total grey and white matter; in the latter case, the volume change was confined to the dorsal white matter. Increased apoptosis, GFAP positive astrocytes, and/or activated microglia were observed in all those CNS regions that showed volume loss except for the hippocampus. The MRM findings in mSOD over-expressing mice are similar to data previously obtained from a model of ALS-parkinsonism dementia complex (ALS-PDC), in which neural damage occurred following a diet of washed cycad flour containing various neurotoxins. The primary difference between the two models involves a significantly greater decrease in spinal cord white matter volume in mSOD mice, perhaps reflecting variations in degeneration of the descending motor tracts. The extent to which several CNS structures are impacted in both murine models of ALS argues for a reevaluation of the nature of the pathogenesis of ALS since CNS structures involved in Parkinson's and Alzheimer's diseases appear to be affected as well.

Expansion of Functional Polyclonal Human T-regulatory Cell Lines Using Artificial Antigen Presenting Cells and Rapamycin. (B159)

T-regulatory CD4+CD25+ T lymphocytes play a central role in regulating immune response and preventing autoimmunity. There is a broad spectrum of potential clinical applications of expanded T-regs including but not limited to treatments of graft versus host disease, transplant rejection, and type I diabetes.

K562 cell line with stable expression of lentivirus-introduced CD64 and CD86 markers (KT64/86) and loaded with anti-CD3 antibodies was used to expand human CD4+CD25 high T lymphocytes. Though in several occasions stimulation of CD4+CD25high cells with KT64/86 only resulted in production of functional T-regulatory cells, only when antibiotic rapamycin was added to the cultures, functional Tregs were produced in 100% of stimulations. These cells were also active in vivo in reversing GVHD in NOG mice. Total CD4 lymphocytes grown in the presence of rapamycin though suppressive in vitro were not able to reverse GVHD in mice.

Substitution of CD86 with CD80 resulted in a less potent Tregs. Addition of certain members of TNF receptor family such as CD70, OX40 ligand or 4-1BB ligand to KT64/86 cells, had different effects on expansion of Treg cell lines. While CD70 addition did not show any impact, 4-1BB and OX-40 ligands in most cases stimulated growth of T-regulatory cell lines but at the same time in most cases also attenuated their activity.

The project is supported by JDRF Collaborative Center for Cell Therapy grant to C.J.

Multiple initial culture conditions enhance the establishment of cell lines from primary ovarian cancer specimens

To increase the efficiency of stable cell line establishment from primary ovarian cancer specimens, we simultaneously initiated cultures under multiple conditions, varying extracellular matrices and the inclusion of supplements (e.g., serum or serum albumin), while minimizing exposure to xenogeneic antigens (e.g., fetal calf serum). Primary cultures were initiated from 30 specimens; cell lines were established from 10 of these for a success rate of 33%. In some instances, multiple cell lines were established from the same specimen. Five lines were characterized extensively with respect to growth properties, antigen expression, and genomic alterations. Although these lines are all low-passage, marked heterogeneity was observed, even between lines derived from the same specimen. The culture approach outlined herein will facilitate generation of reagents useful for many aspects of ovarian cancer biology.

Immunosurveillance and Survivin-Specific T-Cell Immunity in Children With High-Risk Neuroblastoma

Purpose

Tumor immunosurveillance influences oncogenesis and tumor growth, but it remains controversial whether clinical failure of immunosurveillance is a result of lymphocyte dysfunction or tumor escape. In this study, our goal was to characterize the physiology of tumor immunosurveillance in children with high-risk neuroblastoma (HR-NBL).

Patients and Methods

Immunohistopathologic studies were carried out on 26 tumor samples from a cohort of HR-NBL patients diagnosed at Children's Hospital of Philadelphia for the 2-year period from May 2003 to May 2005. Blood from nine HLA-A2+patients in this cohort was analyzed for T cells specific for the antiapoptotic protein survivin.

Results

Survivin protein was expressed by 26 of 26 tumors. In HLA-A2+patients, circulating cytotoxic T lymphocytes (CTLs) specific for survivin were detected by peptide/major histocompatibility complex tetramer analysis in the blood of eight of nine children with HR-NBL at the time of diagnosis. Rather than being selectively rendered anergic in vivo, circulating survivin-specific CTLs were highly functional as shown by cytotoxicity and interferon gamma enzyme-linked immunospot assays in six of nine patients. Survivin-specific CD107a mobilization by T cells was found in five of five patients. By immunohistochemistry, tumor-infiltrating T cells were few or absent in 26 of 26 tumors.

Conclusion

Children with HR-NBL harbor robust cellular immune responses to the universal tumor antigen survivin at the time of diagnosis, but intratumoral T cells are strikingly rare, suggesting a failure of cellular immunosurveillance. Efforts to develop novel therapies that increase T-cell trafficking into tumor nests are warranted.

Regulation of progranulin expression in myeloid cells

Progranulin (pgrn; granulin-epithelin precursor, PC-cell-derived growth factor, or acrogranin) is a multifunctional secreted glycoprotein implicated in tumorigenesis, development, inflammation, and repair. It is highly expressed in macrophage and monocyte-derived dendritic cells. Here we investigate its regulation in myeloid cells. All-trans retinoic acid (ATRA) increased pgrn mRNA levels in myelomonocytic cells (CD34(+) progenitors; monoblastic U-937; monocytic THP-1; progranulocytic HL-60; macrophage RAW 264.7) but not in nonmyeloid cells tested. Interleukin-4 impaired basal expression of pgrn in U-937. Differentiation agents DMSO, and, in U-937 only, phorbol ester [phorbol 12-myristate,13-acetate (PMA)] elevated pgrn mRNA expression late in differentiation, suggestive of roles for pgrn in more mature terminally differentiated granulocyte/monocytes rather than during growth or differentiation. The response of pgrn mRNA to ATRA differs in U-937 and HL-60 lineages. In U-937, ATRA and chemical differentiation agents greatly increased pgrn mRNA stability, whereas, in HL-60, ATRA accelerated pgrn mRNA turnover. The initial upregulation of pgrn mRNA after stimulation with ATRA was independent of de novo protein synthesis in U-937 but not HL-60. Chemical blockade of nuclear factor-kappaB (NF-kappaB) activation impaired ATRA-stimulated pgrn expression in HL-60 but not U-937, whereas in U-937 it blocked PMA-induced pgrn mRNA expression, suggestive of cell-specific roles for NF-kappaB in determining pgrn mRNA levels. We propose that: 1) ATRA regulates pgrn mRNA levels in myelomonocytic cells; 2) ATRA acts in a cell-specific manner involving the differential control of mRNA stability and differential requirement for NF-kappaB signaling; and 3) elevated pgrn mRNA expression is characteristic of more mature cells and does not stimulate differentiation.

Presynaptic localization of a truncated isoform of the type 2 corticotropin releasing factor receptor in the cerebellum

It is now well established that corticotropin releasing factor is present in two major excitatory afferent systems to the cerebellum, namely climbing fibers and mossy fibers. Two major classes of corticotropin releasing factor receptors, each with unique binding characteristics, have been identified as type 1 and type 2. In this study we used an antibody made to the n-terminus of the type 2 corticotropin releasing factor receptor. Characterization of this antibody showed that it strongly labeled a protein with a molecular weight of 16-32 kDa and only faintly labels a 62-83 kDa protein. The lower molecular weight protein corresponds to the weight of a recently described truncated isoform of this receptor that is designated corticotropin releasing factor-type 2alpha-truncated isoform. We carried out transfection paradigms using corticotropin releasing factor-type 2alpha-truncated isoform constructs and confirmed that the antibody recognized the truncated isoform of the type 2 corticotropin releasing factor receptor. Further, light and electron microscopic studies were carried out in mice and rats to define the distribution of the truncated receptor. Immunoreactivity is evident in the basal region of many, but not all Purkinje cell bodies and their initial axonal segments, as well as the initial axonal segments of isolated Golgi cells, and cerebellar nuclear neurons. In addition, punctate elements in the molecular layer were immunolabeled. The localization of the receptor to the initial segment of Purkinje cells was confirmed with electron microscopy. Further, the punctate labeling in the molecular layer was localized to parallel fibers and their terminals. In conclusion, evidence has been presented to show that distinct isoforms of the corticotropin releasing factor receptor are present in the cerebellum. The complex interactions between corticotropin releasing factor and other members of the corticotropin releasing factor family of peptides with both pre- and postsynaptic receptors support a growing concept that corticotropin releasing factor plays an important role in modulating activity in cerebellar circuits and ultimately in controlling motor behavior.

Effects of human soluble BAFF synthesized in Escherichia coli on CD4+ and CD8+ T lymphocytes as well as NK cells in mice

B cell-activating factor belonging to the TNF family (BAFF, also called BLyS, TALL-1, zTNF-4, or THANK) is an important survival factor for B lymphocytes. In this study, we injected mouse abdominal cavity with human soluble BAFF (hsBAFF, 0.01, 0.1, 0.5, 2 mg/kg body mass) synthesized in Escherichia coli. On the 8th day after injection, we investigated the effects of hsBAFF on immune functional activities of splenic B lymphocytes, CD4(+) and CD8(+) T lymphocytes and natural killer (NK) cells in mice. The results showed that B lymphocyte proliferation significantly increased in hsBAFF-treated groups with dosages of 0.1 mg/kg (p<0.05), 0.5 and 2 mg/kg (p<0.01). We observed a dose-dependent increase of CD4(+) T lymphocyte percentage and significantly higher values in 0.5 and 2 mg/kg hsBAFF-treated groups (p<0.05 and p<0.001, respectively) compared to control group, but CD8(+) T lymphocyte percentage remained unchanged. The ratio of CD4(+) to CD8(+) T lymphocytes rose with increasing hsBAFF dosage (p<0.05 for 2 mg/kg hsBAFF vs. control). Significantly stronger NK cell activities were found in 0.5 and 2 mg/kg hsBAFF-treated groups (p<0.05). The main finding of this study is that the hsBAFF can enhance immune responses in the body by increasing B lymphocyte and CD4(+) T lymphocyte function as well as elevating NK cell activity.

Increased phospho-adducin immunoreactivity in a murine model of amyotrophic lateral sclerosis

Adducins alpha, beta and gamma are proteins that link spectrin and actin in the regulation of cytoskeletal architecture and are substrates for protein kinase C and other signaling molecules. Previous studies have shown that expressions of phosphorylated adducin (phospho-adducin) and protein kinase C are increased in spinal cord tissue from patients who died with amyotrophic lateral sclerosis, a neurodegenerative disorder of motoneurons and other cells. However, the distribution of phospho-adducin immunoreactivity has not been described in the mammalian spinal cord. We have evaluated the distribution of immunoreactivity to serine/threonine-dependent phospho-adducin at a region corresponding to the myristoylated alanine-rich C kinase substrate-related domain of adducin in spinal cords of mice over-expressing mutant human superoxide dismutase, an animal model of amyotrophic lateral sclerosis, and in control littermates. We find phospho-adducin immunoreactivity in control spinal cord in ependymal cells surrounding the central canal, neurons and astrocytes. Phospho-adducin immunoreactivity is localized to the cell bodies, dendrites and axons of some motoneurons, as well as to astrocytes in the gray and white matter. Spinal cords of mutant human superoxide dismutase mice having motoneuron loss exhibit significantly increased phospho-adducin immunoreactivity in ventral and dorsal horn spinal cord regions, but not in ependyma surrounding the central canal, compared with control animals. Increased phospho-adducin immunoreactivity localizes predominantly to astrocytes and likely increases as a consequence of the astrogliosis that occurs in the mutant human superoxide dismutase mouse with disease progression. These findings demonstrate increased immunoreactivity against phosphorylated adducin at the myristoylated alanine-rich C kinase substrate domain in a murine model of amyotrophic lateral sclerosis. As adducin is a substrate for protein kinase C at the myristoylated alanine-rich C kinase substrate domain, the increased phospho-adducin immunoreactivity is likely a consequence of protein kinase C activation in neurons and astrocytes of the spinal cord and evidence for aberrant phosphorylation events in mutant human superoxide dismutase mice that may affect neuron survival.

Isomer formation and other issues in the substitution reactions of oxorhenium(V) complexes of 2,2'-bipyridine and related ligands

Two new oxorhenium(V) compounds were prepared and characterized: MeReO(mtp)(Me(2)Bpy) and MeReO(mtp)(dppb), where mtpH(2) is 2-(mercaptomethyl)thiophenol, Me(2)Bpy is 4,4'-dimethyl-2,2'-bipyridine, and dppb is 1,2-(Ph(2)P)(2)C(6)H(4). The more stable geometric isomer of MeReO(mtp)X forms MeReO(mtp)Y (X, Y = PR(3), NC(5)H(4)R) in two steps, both of which show a first-order dependence on [Y], proceeding through the metastable geometric isomer MeReO(mtp)Y. When Y = PR(3), no MeReO(mtp)Y was detected at equilibrium; with NC(5)H(4)R, however, both isomers were detected. The values of K(PyPy) were 8.5-9.8, largely irrespective of R; for NC(5)H(5), DeltaH degrees = -4.47 +/- 0.29 kJ and DeltaS degrees = 3.9 +/- 1.0 J K(-1). For the more symmetric edt ligand, geometric isomers do not exist, but enantiomers do. The rate of racemization of MeReO(edt)(NC(5)H(4)R) was proportional to [Py]. Values of k(rac) for 16 compounds span the range 135-370 L mol(-1) s(-1) in C(6)H(6) at 25 degrees C (rho = -0.39 +/- 0.07). In toluene-d(8), k(rac) for 4-picoline has DeltaH = 28.9 +/- 0.4 kJ, DeltaS() = -103.6 +/- 0.9 J K(-1). A common mechanism applies to ligand substitution (mtp) and racemization (edt). MeReO(dithiolate)Py complexes react with Bpy, Me(2)Bpy, Phen, and Me(2)Phen to form six-coordinate chelates, with rate constants 0.024-0.74 L mol(-1) s(-1) at 25 degrees C, some 10(3) times smaller than with pyridines, no doubt owing to the bulk of the bidentates. Values of DeltaS are -86 to -138 J K(-1), reflecting substantial orientational barriers as well as the inherent contribution of the associative mechanism. The product is MeReO(mtp)(Me(2)Bpy). The formation of the metastable isomer is consistent with the mechanism assigned to the ligand substitution and racemization reactions. Such compounds, once formed, no longer participate in ligand substitution reactions at reasonable rates. The formation of the metastable isomer is consistent with the mechanism assigned to the ligand substitution and racemization reactions.

Luminol chemiluminescence in unbuffered solutions with a cobalt(II)-ethanolamine complex immobilized on resin as catalyst and its application to analysis

Using a heterogeneous catalyst, Co(II)-ethanolamine complex sorbed on Dowex-50W resin, the chemiluminescence (CL) of luminol in unbuffered or weakly acidic solution was studied in the presence of H2O2. The maximum luminol CL wavelength at pH 5.7 was 448 nm, 23 nm longer than that in a basic solution (pH 10.5). Three different ligands, mono-, di-, and triethanolamine, and six transition metal ions, Co(II), Cu(II), Ni(II), Mn-(II), Fe(II), and Fe(III) were compared by CL measurements. The CL intensity decreased in the order mono- > di- > triethanolamine and Co(II) > Cu(II) > Ni(II) > Fe-(III) > Mn(II) > Fe(II). This heterogeneous CL system was developed as H2O2 and glucose flow-through sensors. Detection limits (S/N = 3) of H2O2 and glucose using Dowex-50W-X4-Co(II)-monoethanolamine as catalyst are 1 x 10(-7) M and 1 x 10(-6) M, respectively. On the basis of the studies of the CL, fluorescence, UV-vis and ESCA spectra and the effect of dissolved oxygen in luminol solution, a mechanism for CL emission in unbuffered solution was considered as the formation of a superoxide radical ion during the decomposition of H2O2 catalyzed by the Co(II)-ethanolamine immobilized resin. Then the superoxide radical ion acted on luminol and the CL was emitted. The applications of the proposed method to determine H2O2 in rainwater without any special pretreatment and glucose in human urine and orange juice samples give satisfactory results.

Zap-70-independent Ca(2+) mobilization and Erk activation in Jurkat T cells in response to T-cell antigen receptor ligation

The tyrosine kinase ZAP-70 has been implicated as a critical intermediary between T-cell antigen receptor (TCR) stimulation and Erk activation on the basis of the ability of dominant negative ZAP-70 to inhibit TCR-stimulated Erk activation, and the reported inability of anti-CD3 antibodies to activate Erk in ZAP-70-negative Jurkat cells. However, Erk is activated in T cells receiving a partial agonist signal, despite failing to activate ZAP-70. This discrepancy led us to reanalyze the ZAP-70-negative Jurkat T-cell line P116 for its ability to support Erk activation in response to TCR/CD3 stimulation. Erk was activated by CD3 cross-linking in P116 cells. However, this response required a higher concentration of anti-CD3 antibody and was delayed and transient compared to that in Jurkat T cells. Activation of Raf-1 and MEK-1 was coincident with Erk activation. Remarkably, the time course of Ras activation was comparable in the two cell lines, despite proceeding in the absence of LAT tyrosine phosphorylation in the P116 cells. CD3 stimulation of P116 cells also induced tyrosine phosphorylation of phospholipase C-gamma1 (PLCgamma1) and increased the intracellular Ca(2+) concentration. Protein kinase C (PKC) inhibitors blocked CD3-stimulated Erk activation in P116 cells, while parental Jurkat cells were refractory to PKC inhibition. The physiologic relevance of these signaling events is further supported by the finding of PLCgamma1 tyrosine phosphorylation, Erk activation, and CD69 upregulation in P116 cells on stimulation with superantigen and antigen-presenting cells. These results demonstrate the existence of two pathways leading to TCR-stimulated Erk activation in Jurkat T cells: a ZAP-70-independent pathway requiring PKC and a ZAP-70-dependent pathway that is PKC independent.

Uptake and distribution of rare earth elements in rice seeds cultured in fertilizer solution of rare earth elements

The uptake behavior of rare earth elements (REEs) under pot conditions using deionized water and a REE fertilizer solution as the culture media as well as the distribution of REEs in rice proteins were studied. The uptake of REEs in rice seeds increased dramatically after a lag period of approximately three days. Roots can accumulate a much higher content of REEs than germs and the resting seeds. The REE content in each water-soluble (albumin) and salt-soluble (globulin) component of the rice seeds accounted for 5-8% and 4-6% of the total REEs, respectively. However, there are less than 1.5% of the total REEs were found in the alcohol-soluble (prolamin) and acetic acid-soluble (glutelin) components. The high performance liquid chromatography (HPLC) in the gel permeation and the reserved-phase were used to monitor changes in the molecular weight distribution changes of the soluble proteins of rice seeds during germination after having been cultured in the same solution for seven days. No changes occurred in the prolamin, while a slight change occurred in the albumin, globulin and glutelin. Fractionation of the albumin of rice seeds cultured in a REE fertilizer solution on the Sephadex G-100 column indicated that REEs, especially Ce, La, Pr and Nd, were associated mainly with biological compounds of a molecular weight between 10,000 and 12,000.

Mutations in the regulatory domain of cystathionine beta synthase can functionally suppress patient-derived mutations in cis

Human cystathionine beta--synthase (CBS) is an S-adenosylmethionine-regulated enzyme that plays a key role in the metabolism of homocysteine. Mutations in CBS are known to cause homocystinuria, an inborn error in metabolism. We previously developed a yeast functional assay for CBS and used it to characterize mutations found in homocystinuric patients. We discovered that many patient-derived mutations are functionally suppressed by deletion of the C-terminal 142 amino acids, which contain a 53 amino acid motif known as the CBS domain. This domain is found in a wide variety of proteins of diverse biological function. Here we have used a genetic screen to identify missense mutations in the C-terminal region of CBS that can suppress the most common patient mutation, I278T. Seven suppressor mutations were identified, four of which map to the CBS domain. When combined in cis with another pathogenic mutation, V168M, six of seven of the suppressor mutations rescued the yeast phenotype. Enzyme activity analyses indicate that the suppressors restore activity from <2% to 17--64% of the wild-type levels. Analysis of the suppressor mutations in the absence of the pathogenic mutation shows that six of the seven suppressor alleles have lost enzymatic responsiveness to S-adenosylmethionine. Using homology modeling, we show that the suppressor mutations appear to map on one face of the CBS domain. Our results indicate that subtle changes to the C-terminus of CBS can restore activity to mutant proteins and provide a rationale for screening for compounds that can activate mutant CBS alleles.

[Detection of TT virus DNA and sequence analysis of TTV gene in sera from young children in Nanjing]

OBJECTIVE

To investigate the prevalence of TTV genomes in young children from Nanjing and establish the PCR method for detecting TTV DNA.

METHODS

A hemi-nested polymerase chain reaction (PCR) assay was established to detect TTV DNA in 110 young children and two PCR-amplified products were sequenced and the data were analyzed with the computer programs.

RESULTS

TTV DNA was detected in 14 out of 110 children, and 222 bp sequences of 2 isolates from the children were analyzed. Compared with representative of published isolates, they have the nucleotide identity of 93.7%-98.6% with TX011.

CONCLUSIONS

The infection rate of TTV in children is 12.73%, and 2 isolates from children belong to subgroup G1b. Our results indicates that TTV could be transmitted via other pathway besides hematogenous one, and TTV could be carried by healthy population.

A role for Drosophila Drac1 in neurite outgrowth and synaptogenesis in the giant fiber system

Recent studies have shown the small GTPases, Rac1, Rho, and CDC42, to have a role in axon guidance. To assess their participation in synapse assembly and function we have expressed various forms of Drac1 in the giant fiber system of Drosophila. Overexpression of wild-type Drac1 in the giant fiber (GF) lead to a disruption in axonal morphology; axons often terminate prematurely in a large swelling in the target area but lack the normal lateral bend where the synapse with the jump motor neuron would normally be found. Electrophysiological assays revealed longer latencies and lowering following frequencies indicating defects in the synapse between the GF and the tergotrochanteral motor neuron (TTMn). Thickened abnormal GF dendrites were also observed in the brain. Overexpression of the dominant-negative form of Drac1, (N17), resulted in axons that produced extra branches in the second thoracic neuromere (T2); however, the synaptic connection to the TTMn was present and functioned normally. Conversely, expression of the constitutively active form, Drac1(V12), resulted in a complete lack of neurite outgrowth and this was also seen with overexpression of Dcdc42(V12). In the absence of a GF, these flies showed no response in the jump (TTM) or flight (DLM) muscles upon brain stimulation. Taken together these results show that the balance of actin polymerization and depolymerization determines local process outgrowth and thereby synapse structure and function.

Relations of tumor suppressor gene p16 and RB to early diagnosis of lung cancer

OBJECTIVES

To study the incidence and mechanism of the tumor suppressor gene p16 and RB inactivation in lung cancer, and to investigate their relations to biological characteristics, clinical pathological diagnosis and gene classification.

METHODS

Immunohistochemistry, double in situ hybridization, PCR, PCR-SSCP, and sequencing were used to study the changes in the p16 and RB genes in 106 patients with lung cancer. The specimen of normal lung tissue from the patients with lung cancer and specimens of the 23 patients with benign lung diseases were studied in contrast to those of the same patients.

RESULTS

The total expression rate of the p16 and RB genes in the lung cancer tissues of the 106 patients was lower than that in normal lung tissues and tissues of benign lung diseases and was specially related to histological type, metastasis, and clinical stage of lung cancer. In stage I and II lung cancer, the obvious inactivation rate of the tumor suppressor gene p16 or RB was 32.6% or 28.3%. The p16 inactivation appeared largely in non-small cell lung cancer (50.1%), and the RB inactivation largely in small cell lung cancer (88.2%). Homozygous deletion, methylation, and mutation were three mechanisms for the p16 gene inactivation. The deletion rate of the p16 exon 1 and/or exon 2 was 25.8% in the patients with non-small cell lung cancer. Fifteen patients (16.9%) showed methylation at the SmaI sites of CpG island of the p16 gene. PCR-SSCP and sequencing revealed p16 gene mutation in 9 of the 106 patients with lung cancer.

CONCLUSIONS

The p16 and RB genes may play an important role in genesis and progression of lung cancer. The inactivation of the p16 or RB gene may be an early sign of lung canceration, that is important for the early diagnosis. A new gene classification model for lung cancer diagnosis would be set up based on the research of the p16 and RB genes.

Deficiency of PTEN in Jurkat T cells causes constitutive localization of Itk to the plasma membrane and hyperresponsiveness to CD3 stimulation

Pleckstrin homology (PH) domain binding to D3-phosphorylated phosphatidylinositides (PI) provides a reversible means of recruiting proteins to the plasma membrane, with the resultant change in subcellular localization playing a key role in the activation of multiple intracellular signaling pathways. Previously we found that the T-cell-specific PH domain-containing kinase Itk is constitutively membrane associated in Jurkat T cells. This distribution was unexpected given that the closely related B-cell kinase, Btk, is almost exclusively cytosolic. In addition to constitutive membrane association of Itk, unstimulated JTAg T cells also exhibited constitutive phosphorylation of Akt on Ser-473, an indication of elevated basal levels of the phosphatidylinositol 3-kinase (PI3K) products PI-3,4-P(2) and PI-3,4,5-P(3) in the plasma membrane. Here we describe a defect in expression of the D3 phosphoinositide phosphatase, PTEN, in Jurkat and JTAg T cells that leads to unregulated PH domain interactions with the plasma membrane. Inhibition of D3 phosphorylation by PI3K inhibitors, or by expression of PTEN, blocked constitutive phosphorylation of Akt on Ser-473 and caused Itk to redistribute to the cytosol. The PTEN-deficient cells were also hyperresponsive to T-cell receptor (TCR) stimulation, as measured by Itk kinase activity, tyrosine phosphorylation of phospholipase C-gamma1, and activation of Erk compared to those in PTEN-replete cells. These data support the idea that PH domain-mediated association with the plasma membrane is required for Itk activation, provide evidence for a negative regulatory role of PTEN in TCR stimulation, and suggest that signaling models based on results from Jurkat T-cell lines may underestimate the role of PI3K in TCR signaling.

Syntheses and structures of rhenium(IV) and rhenium(V) complexes with ethanedithiolato ligands

A novel dimeric rhenium(IV) complex, [Re2(SCH2CH2S)4], and a monomeric methyloxorhenium(V) complex, [CH3ReO(SCH2CH2S)PPh3], were synthesized from methyloxorhenium(V) complexes and characterized crystallographically. The structure of [Re2(SCH2CH2S)4], the formation reaction of which showed surprising demethylation conceivably through the homolytic cleaveage of the rhenium-carbon bond, features distorted trigonal prismatic coordination of sulfurs around the metal center and a rhenium-rhenium triple bond. A revised structure, [Tc2(SCH2CH2S)4], is proposed for a related technetium complex, originally identified as [Tc2(SCH2CH2S)2(SCH=CHS)2] (Tisato et al. Inorg. Chem. 1993, 32, 2042). Additionally, a new compound, CH3Re(O)(SPh)2PPh3, was prepared.

Increased nondisjunction of chromosome 21 with age in human peripheral lymphocytes

Fluorescence in situ hybridization (FISH) on binucleated cells with chromosome-specific DNA probes provides a convenient way to visualize reciprocal segregation patterns in daughter nuclei, and overcomes most problems related to the artefactual loss or gain of chromosomes that flaw chromosome preparations. In this study, FISH was employed to evaluate age- and sex-effects on spontaneous malsegregation, nondisjunction and loss of chromosome 21 in human lymphocytes after the first division in culture. A total of 68 healthy nonsmokers and nondrinkers of alcohol (37 males and 31 females) were grouped by age as Group I (0-10 years), Group II (20-30 years), Group III (40-50 years) and Group IV (60-70 years), with at least seven subjects per group and sex. FISH with a pericentric chromosome 21 specific DNA probe was carried out on binucleated lymphocytes, cytokinesis-blocked by cytochalasin B (6 microg/ml for 26 h) at 44 h after initiation of cultures. Linear regression analyses demonstrated a significant age-related increase in the frequency of micronuclei without chromosome 21 (MN-21)(r=0.73, p<0.001 in females; r=0.69, p<0.001 in males) in all binucleated cells, with a steeper slope in females (0.1758) than in males (0. 1241). Analysis using the 2x2 chi-square (chi(2)) test on the frequencies of MN-21 showed significant age-related differences in both males and females, except males in Group III and Group IV (p>0. 05). A significant sex-related difference was found only in subjects over 60 years (p<0.05), with females having more MN-21 (12.57 per thousand vs. 8.43 per thousand) than males. Loss of chromosome 21, occurring at mean levels of 0.38 per thousand in all binucleated cells and 0.24 per thousand in binucleated cells containing four FISH signals, was shown not to be age- or sex-related. A positive age-related increase in nondisjunction of chromosome 21 was shown in males (r=0.50, p<0.01), females (r=0.61, p<0.001) and all subjects (r=0.55, p<0.001) by linear regression analysis. An age effect was found only between children and adults (p<0.01 for females, p<0.05

[Relationship between tumor suppressor gene p16 and Rb and early diagnosis of lung cancers]

OBJECTIVES

To study the incidences and mechanisms of tumor suppressor gene p16 and Rb inactivation in lung cancers, and to investigate their relation to biological characters, clinical pathological diagnosis and gene classification diagnosis of lung cancers.

METHODS

Immunohistochemistry, double in situ hybridization, PCR, PCR-SSCP and sequencing were applied to study the changes of p16 and Rb genes in 106 lung cancers and 23 lung tissues of benign diseases.

RESULTS

Total expression rates of p16 and Rb proteins and mRNAs in lung cancers were lower than those in normal lung tissues and benign lung diseases, and they were specially related to histological type, metastasis and clinical stage of lung cancers. In stage I and II lung cancers, the obvious inactivation of tumor suppressor gene p16 or Rb was examined (32.6% or 28.3%); p16 inactivation was detected mainly in non-small cell lung cancers, and Rb inactivation mainly in small cell lung cancers. There were three mechanisms of homozygous deletions, methylations and mutations for p16 gene inactivation. The deletion rate of p16 exon1 and/or exon2 was 25.8%, mainly took place in p16 protein negative cases of non-small cell lung cancers. 15 cases (16.9%) took part in methylations on SmaI sites of CpG island of p16 gene. PCR-SSCP and sequencing showed that 9 cases had p16 gene mutations.

CONCLUSIONS

p16 and Rb genes may play important roles in genesis and progression of lung cancers. Inactivation of p16 or Rb gene may be is an early link of lung canceration, that is very important for early diagnosis of lung cancers. A new gene classification model for lung cancer diagnosis would be set up based on the research of p16 and Rb genes.

[CDKN2/p16 gene cloning and its probe preparation and application in lung cancer]

OBJECTIVES

To clone CDKN2/p16(INK4a) gene, prepare its probe, and to study the change of CDKN2/p16(INK4a) gene in lung cancers.

METHODS

Total RNA of normal lung tissue was extracted, CDKN2/p16(INK4a) gene cDNA synthesized, and CDKN2/p16(INK4a) gene recombinant vector, constructed. Southern blot was used to study CDKN2/p16(INK4a) gene in 46 cases of lung cancers, 3 cases of normal lung tissues, 6 cases of lung tissues near cancer, and 3 cases of lymph nodes with lung cancer metastasis.

RESULTS

Cloned CDKN2/p16(INK4a) cDNA was proved by enzyme digestion and sequencing. Southern blot showed 4.3 kb band in normal lung tissues and lung tissues near cancers, and deletion of CDKN2/p16(INK4a) gene in cancer tissues and lymph nodes with lung cancer metastasis, with a deletion rate of 17.4% (8/46).

CONCLUSION

CDKN2/p16(INK4a) gene may play a role to some extent in progression of lung cancers.

Detection of mosaic chromosome 21 aneuploidy in vivo with CB-FISH method

OBJECTIVE

To explore the mechanism by which the ratio of mosaic diploid cells in vivo increased in trisomy 21 cases.

METHODS

Fluorescence in situ hybridization (FISH) with pericentric DNA probes specific to human chromosome 21 to the binucleated cells cytokinesis- blocked by cytochalasin-B(CB), namely, CB-FISH method.

RESULTS

The mean frequency of diploid cells (1.69%+/-1.07%) was significantly higher than that of tetrasomy 21 cells(0.042%+/-0.064%)(P=0.000) in 12 trisomy 21 cases aged 0-9 years (mean 4 years) in vivo; whereas the incidence of spontaneous monosomy 21 cells (0. 265%+/-0.13%) was close to the frequency of trisomy 21 cells (0. 225%+/-0.184%) in 20 control individuals aged 0-10 years (mean 5 years). The frequency of cells undergone chromosome 21 nondisjunction was 0.822%+/-0.554% in cultured trisomy 21 cells, which was significantly higher than that in the cultured diploid cells (0.369%+/-0.25%). However, the rates of cells with chromosome 21 loss in the two cultured cell lines (0.01%+/-0.03% vs 0.043%+/-0.049%) were not significantly different. In both cultured cell lines, chromosome 21 nondisjunction occurred more frequently than loss.

CONCLUSION

The increased frequency of diploidies in trisomy 21 cases may result from the accumulation of diploid cells originating from malsegregation of chromosome 21 in trisomic cells rather than the increase of chromosome 21 loss.

[Thiol reagent thimerosal-induced Ca2+ mobilization in isolated guinea pig cochlear outer hair cells]

OBJECTIVE

To understand mechanism of cochlear outer hair cells (OHCs) intracellular Ca2+ mobilization further.

METHODS

Intracellular calcium of isolated guinea pig was investigated using thimerosal, a--SH group oxidizing agent, and fura-2 fluorescence ratio imaging microscopy.

RESULTS

In the presence of thimerosal, intracellular Ca2+ concentrations ([Ca2+]i) of OHCs were elevated in a dose-dependent manner. Even in Ca(2+)-free medium, Ca2+ response was still induced. The effects of thimerosal on [Ca2+]i were completely blocked and reversed by (DTT). Neither 1-100 mumol/L ryanodine nor 5-20 mmol/L caffeine altered the effects of thimerosal. Pretreatment with pertussis toxin (PTX) for 30 min did not affect the thimerosal-induced increase in [Ca2+]i The increase in [Ca2+]i when Ca2+ was added during thimerosal application in Ca(2+)-free medium was almost completely blocked by 500 mol/L LaCl3, while nifedipine did not inhibit further increase in [Ca2+]i caused by thimerosal.

CONCLUSION

Oxidation of the -SH group of the OHC membrane can induce a Ca2+ release from intracellular Ca2+ stores, which are ryanodine- and caffeine-insensitive, and Ca2+ influx through non-specific Ca2+ channels, but not the nifedipine-sensitive Ca2+ Channels. The possible oxidation of--SH group gated Ca2+ channels in OHCs are worthy of further study.

[Correlation of inactivation of CDKN2/p16 gene by methylation and lung cancers]

OBJECTIVE

To study the relationship between methylation state of CDKN2/p16 gene and lung cancers.

METHODS

Genomic DNA was digested with methylation-sensitive enzymes and Southern blotting was used to analyses the methylation state of CDKN2/p16 gene in 89 cases of lung cancer.

RESULTS

Twenty-one out of 89 lung cancers(23.6%) shown methylation of CDKN2/p16 gene, and 17 of them occurred in 42 P16 negative cases with a rate of 40.5%(17/42).

CONCLUSION

Methylation of CDKN2/p16 gene 5' CpG island is probably an important mechanism of gene inactivation; it may take part in the onset and process of lung cancer.

Self-organized criticality in a computer network model

We study the collective behavior of computer network nodes by using a cellular automaton model. The results show that when the load of network is constant, the throughputs and buffer contents of nodes are power-law distributed in both space and time. Also the feature of 1/f noise appears in the power spectrum of the change of the number of nodes that bear a fixed part of the system load. It can be seen as yet another example of self-organized criticality. Power-law decay in the distribution of buffer contents implies that heavy network congestion occurs with small probability. The temporal power-law distribution for throughput might be a reasonable explanation for the observed self-similarity in computer network traffic.

The Drosophila sox gene, fish-hook, is required for postembryonic development

In Drosophila, the fish-hook (fish) gene encodes a Sox protein essential for embryonic segmentation and nervous system organization. In this study we examined potential functional roles of fish in postembryonic developmental processes, including those involved in adult appendage development. We show here that Fish protein is expressed in discrete patterns in the larval eye-antennal and leg imaginal discs, the central nervous system, the hindgut, and salivary glands. Genetic mosaic studies indicated that fish function is required for the growth or survival of imaginal cells, and the expression of engrailed and wingless. Ectopic expression of Fish protein resulted in severe disruption of adult structures; legs and antennae were truncated and eye formation was suppressed. These morphological defects were correlated with altered expression patterns of the wingless, decapentaplegic, and bric-a-brac genes. Finally, analysis of truncated versions of Fish protein indicated that the HMG domain was sufficient for Fish nuclear localization and that removal of the transcriptional activation domain did not eliminate Fish function. While Sox proteins have been shown to be important for eye and limb formation in vertebrates, these data provide the first evidence for Sox protein functions in appendage development in invertebrates.

Incidence of mosaic cell lines in vivo and malsegregation of chromosome 21 in lymphocytes in vitro of trisomy 21 patients: detection by fluorescence in situ hybridization on binucleated lymphocytes

In order to detect aneuploidy in interphase human lymphocytes, both in vivo and in vitro, fluorescence in situ hybridization (FISH) was carried out on binucleated cells cytokinesis-blocked by cytochalasin B at the first mitosis after phytohemagglutinin stimulation. A pericentric chromosome-21-specific DNA probe prepared from yeast artificial chromosome clone 881D2 by the polymerase chain reaction was employed. One thousand binucleated cells per individual were scored from cultures from twelve trisomy 21 patients aged 0.01-8.9 years (mean 4.3 years) and 20 normal children of similar age. Of trisomy 21 patients, increased frequencies of disomic cells in vivo (1.690+/-1.070%) and cells containing six signals with nondisjunction (0.822+/-0.554%) were found, compared with those of monosomic 21 cells in vivo (0.265+/-0.130%) and cells containing four signals with nondisjunction in normal children (0.369+/-0.250%; P=0.000 and P=0.000, respectively). These results show that malsegregation of chromosome 21 occurs more often in trisomic 21 cells than in disomic cells from normal children. The frequency of nondisjunction was significantly higher than the loss of chromosome 21 in both cultured trisomic (0.822+/-0.554% vs 0.043+/-0.049%, P=0.000) and disomic (0.369+/-0.250% vs 0.010+/-0.30%, P=0.000) cells. Comparisons of in vivo and in vitro data on aneuploidy indicate that a cell selection mechanism may exist in vivo. All these results show that FISH, with a chromosome-specific probe, on binucleated lymphocytes is a powerful tool for simultaneously detecting mosaic cell lines in vivo and malsegregation (loss and nondisjunction) of a corresponding chromosome in vitro in the same cell population.

Functional characterization of human methylenetetrahydrofolate reductase in Saccharomyces cerevisiae

Human methylenetetrahydrofolate reductase (MTHFR, EC 1.5.1.20) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. 5-Methyltetrahydrofolate is a major methyl donor in the remethylation of homocysteine to methionine. Impaired MTHFR can cause high levels of homocysteine in plasma, which is an independent risk factor for vascular disease and neural tube defects. We have functionally characterized wild-type and several mutant alleles of human MTHFR in yeast, Saccharomyces cerevisiae. We have shown that yeast MET11 is a functional homologue of human MTHFR. Expression of the human MTHFR cDNA in a yeast strain deleted for MET11 can restore the strain's MTHFR activity in vitro and complement its methionine auxotrophic phenotype in vivo. To understand the domain structure of human MTHFR, we have truncated the C terminus (50%) of the protein and demonstrated that expressing an N-terminal human MTHFR in met11(-) yeast cells rescues the growth phenotype, indicating that this region contains the catalytic domain of the enzyme. However, the truncation leads to the reduced protein levels, suggesting that the C terminus may be important for protein stabilization. We have also functionally characterized four missense mutations identified from patients with severe MTHFR deficiency and two common missense polymorphisms found at high frequency in the general population. Three of the four missense mutations are unable to complement the auxotrophic phenotype of met11(-) yeast cells and show less than 7% enzyme activity of the wild type in vitro. Both of the two common polymorphisms are able to complement the growth phenotype, although one exhibited thermolabile enzyme activity in vitro. These results shall be useful for the functional characterization of MTHFR mutations and analysis structure/function relationship of the enzyme.