Antibody-IL-12 fusion proteins are effective in SCID mouse models of prostate and colon carcinoma metastases

IL-12 is a complex cytokine in both its structure and its range of biologic activities. Fusions of this heterodimeric molecule with an intact antitumor Ab were made to test the feasibility and efficacy of targeting IL-12 to tumors to elicit a local immune response. Fusion proteins composed of the human p35 and p40 subunits had IL-12 bioactivities that were nearly as potent on human immune cells as the rIL-12 standard, but were inactive on mouse cells. Hybrid IL-12 fusion proteins composed of mouse p35 and human p40, fused to Ab, were capable of inducing IFN-gamma, but were much less active on mouse spleen cells than a mouse IL-12 standard. Despite this relatively low activity, the hybrid fusion protein was as effective in a SCID mouse model as a fully active Ab-IL-2 fusion protein in eliminating established pulmonary metastases of CT26 colon carcinoma. Specific targeting of a human IL-12 fusion protein to metastatic prostate carcinoma xenografts was also shown to be effective in SCID mice transplanted with human lymphocyte-activated killer cells. These results demonstrate the importance of directing this potent cytokine to the tumor microenvironment and suggest an important alternative to systemic IL-12 administration or gene therapy for increasing its therapeutic index.

Absence of autophosphorylation site Y882 in the p185neu oncogene product correlates with a reduction of transforming potential

Autophosphorylation of type I receptor tyrosine kinases (RTKs) comprises one step in the signaling events mediated by erbB receptors such as p185neu and EGFR. Previous analysis of p185neu has indicated that there are at least five tyrosine autophosphorylation sites, Y882, Y1028, Y1143, Y1226/7 and Y1253, of which Y882 might be important because of its location in the kinase activity domain. We have specifically analysed the effect of a Y882F (phenylalanine substituted for tyrosine at position 882) mutation in the enzymatic active domain. We also deleted the carboxyl terminal 122 amino acids which contained three other autophosphorylation sites (TAPstop) and combined mutants of that deletion with Y882F (Y882F/APstop). Both in vitro and in vivo transformation assays showed that substitution of tyrosine882 by phenylalanine significantly decreased the transforming potential of activated, oncogenic p185neu, although no significant difference in the total phosphotyrosine levels of the mutant proteins were observed. To analyse mitogenic signaling in response to ligand, the intracellular domains of p185neu and Y882F were fused with the extracellular domain of the EGF receptor. The proliferation of cells expressing these chimeric receptors was EGF-dependent, and cells expressing EGFR/Y882F chimeric receptors were less responsive to EGF stimulation than those expressing EGFR/neu receptors. In vitro kinase assays demonstrated that abolishing the autophosphorylation site Y882 diminished the enzymatic tyrosine kinase activity of p185neu. These studies, taken together with the phenotypic inhibition observed with cells expressing Y882F, suggest that the tyrosine882 residue may be important for p185neu-mediated transformation by affecting the enzymatic kinase function of the p185neu receptor.

Low expression of the apolipoprotein B mRNA-editing transgene in mice reduces LDL levels but does not cause liver dysplasia or tumors

Hepatic expression of apolipoprotein (apo) B mRNA-editing enzyme catalytic polypeptide 1 (APOBEC-1) has been proposed as a gene therapy approach for lowering plasma low density lipoprotein (LDL) levels. However, high-level expression of APOBEC-1 in transgenic mouse and rabbit livers causes liver dysplasia and hepatocellular carcinoma. To determine the physiological and pathological effects of low-level hepatic expression of APOBEC-1, we used a 52-kb rat APOBEC-1 genomic clone (RE4) to generate transgenic mice expressing low levels of APOBEC-1 (2 to 5 times those in nontransgenic mice). Liver function, liver histology, editing of apoB mRNA at the normal editing site (C6666), and abnormal editing at multiple sites (hyperediting) in these mice were compared with those in transgenic mice expressing intermediate (I-20) or high (I-28) levels of APOBEC-1 in the liver. Hyperediting of mRNA coding for the novel APOBEC-1 target 1 (NAT1) was also examined. In the high-expressing I-28 line, 50% of the mice had palpable tumors at 15 weeks of age, whereas in the intermediate-expressing I-20 line, 50% of the mice had evidence of liver tumors after 1 year. In contrast, low-expressing RE4 mice had normal liver function and histology and did not develop liver tumors when examined at 3 to 17 months of age. Moreover, hyperediting of apoB and NAT1 mRNA in the liver was robust in the I-20 mice but barely detectable in the RE4 mice. The low-level expression resulted in sufficient APOBEC-1 to edit essentially all apoB mRNA at the normal editing site, virtually eliminating apoB-100 and LDL in the plasma of RE4 mice. When RE4 mice were crossed with human apoB transgenic mice, which possess high plasma LDL concentrations, plasma LDL levels in the offspring were reduced to very low levels. These results indicates that long-term hepatic expression of APOBEC-1 at low levels sufficient to eliminate LDL does not cause apparent liver damage or liver tumors in transgenic mice. RE4 APOBEC-1 transgenic mice should prove valuable for studying the roles of apoB-containing lipoproteins in lipid metabolism and atherosclerosis.

N-hydroxysuccinimide ester labeling 5'-aminoalkyl DNA oligomers: reaction conditions and purification

Difficulties were encountered in labeling 5'-aminoalkyl DNA oligomers with glycolketo electrophore N-hydroxysuccinimide esters in aqueous sodium bicarbonate (a common base for this purpose), followed by C18-silica reversed-phase high-performance liquid chromatography (HPLC) to achieve purification. The electrophore-labeled oligomers were not separated readily either from the hydrolyzed electrophore or from the starting oligomer. This problem was overcome by conducting the reaction with triethylamine as a base, organic washing the reaction mixtures after evaporation, and separating on a C18-poly(styrene-divinylbenzene) HPLC packing.

Phosphatidylcholine activation of bacterial phosphatidylinositol-specific phospholipase C toward PI vesicles

The effect of different phospholipids on the kinetic behavior of phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis toward PI vesicles has been investigated. Cosonicated PC/PI vesicles displayed enhanced hydrolysis of PI when less than 0. 20 mole fraction PC was incorporated into the vesicle; higher mole fractions of PC led to a decrease from the maximum activity mimicking surface dilution of substrate. Since the PC could affect PI-PLC binding to vesicles, the effect of separate PC vesicles on enzymatic hydrolysis of PI vesicles was examined. Separate phosphatidylcholine vesicles were found to activate PI-PLC-catalyzed cleavage of PI vesicles up to 7-fold. The activation was completely abolished when the PC vesicle was composed of cross-linked molecules. In the absence of enzyme, fluorescence resonance energy transfer studies did not detect any fusion between PI and PC vesicles if the total lipid concentration was below 2 mM. Higher total lipid concentrations (>20 mM) increased PC transfer between PC and PI vesicles, producing a PI vesicle population with small amounts of PC in the outer monolayer. This suggested that the activation of PI-PLC toward PI vesicles reflects the time scale of transfer of PC from PC vesicles to PI vesicles. Cosonicated PC/PI vesicles provide a measure of enzyme activity versus mole fraction of PC that can be used to estimate the extent of vesicle exchange or fusion between separate vesicle pools. The effects of other phospholipid vesicles on PI-PLC hydrolysis of PI were also examined; zwitterionic lipids were activators while anionic phospholipids inhibited activity. The results indicated that PC molecules in the PI interface allosterically bind to PI-PLC and help anchor enzyme in a more active conformation to the PI interface.

Expression of D-type cyclins in normal and neoplastic rat pituitary

The D-type cyclins (D1, D2, and D3) are involved in progression through the G1 phase of the cell cycle and are induced as part of the delayed early response to growth factor stimulation. To better understand the role of D-type cyclins in pituitary cell function and the regulatory role of growth factors in the cell cycle, we analyzed the expression and regulation of D-type cyclins in normal and neoplastic rat pituitary cells. Immunocytochemical and RT-PCR analyses showed expression of all three D-type cyclins in the normal pituitary, with higher percentages of positive cells by immunocytochemistry in the nuclei of normal pituitaries (D1, 20-30%; D2, 50-60%; D3, 70-80%), compared with GH3 cells. In the normal pituitary, there were significantly higher levels of cyclins D2 and D3 in PRL, GH, LH, and TSH cells, compared with ACTH cells. Cyclin D1 protein was not detected in GH3 cells, while D2 was present in less than 1 percent and D3 in 10-15 percent of GH3 cells. There were low levels of cyclin D1 and D2 messenger RNA expression in GH3 cells, by RT-PCR. When dissociated rat pituitary cells were cultured in the presence of basic fibroblast growth factor (5.6 nM) for 3 days, cyclin D2 was up-regulated 2-fold in normal PRL cells (control, 33 +/- 1%; treated, 68 +/- 2%). Similarly, bFGF treatment stimulated cyclin D3 expression 3-fold in GH3 cells (control, 15 +/- 1%; treated, 44 +/- 1%). Treatment of GH3 cells with 5-aza-2'-deoxycytidine, which induces gene demethylation, produced marked increases in cyclin D2 and D3 expression. Transfection of mouse cyclin D1 complementary DNA, driven by a cytomegalovirus promoter into GH3 cells, led to ectopic cyclin D1 expression; and there was a slight stimulation of cell proliferation and increased apoptosis in GH3 cells. These results indicate that there is a differential expression of various D-type cyclins in different types of normal pituitary cells and between normal pituitary and GH3 cells. Growth factors, such as bFGF and demethylation increased D-type cyclin expression, whereas ectopic overexpression of cyclin D1 stimulates cell proliferation and increases apoptosis in GH3 pituitary tumor cells.

Isolation and characterization of a skate retinal GABA transporter cDNA

PURPOSE

The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is believed to play a crucial role in the processing of information within the vertebrate retina. Extracellular concentrations of GABA are thought to be tightly regulated by carrier-mediated transport proteins in neurons and glial cells. The purpose of this work was to isolate the gene that encodes one of these transport proteins in the skate retina.

METHODS

cDNA clones were isolated from a skate retinal cDNA library using a mouse retinal GABA transporter (GAT1) cDNA as a probe. The PCR technique was used to fill sequence gaps, and 5' and 3' RACE were employed to amplify the 5' and 3' untranslated regions. The amplified fragments were subcloned into a T-vector. Blots containing RNA from 10 different tissues were probed to determine the size of the transcript and the tissue distribution.

RESULTS

Sequence analysis revealed that the skate retinal GABA transporter cDNA shared 72% identity with the mouse GABA transporter-1 at the DNA level and 80% identity at the amino acid level. Multiple sequence alignments showed that our sequence is closest to the Torpedo GABA transporter-1. Two transcripts, 4.5 and 7 kb, were detected in retina and possibly brain by RNA blot analysis. Fourteen introns were detected in the skate GABA transporter gene.

CONCLUSIONS

We successfully isolated a full length GABA transporter cDNA from the retina of the skate. The size of the full length sequence of the skate retinal GABA transporter is in agreement with the size of the smaller transcript detected on RNA blots. The larger transcript observed on the RNA blot may be the result of either alternative splicing or utilization of a downstream poly A signal.

Inhibition of a naturally occurring EGFR oncoprotein by the p185neu ectodomain: implications for subdomain contributions to receptor assembly

Mutant Epidermal Growth Factor Receptor (EGFR) oncoproteins lacking most of subdomains I and II of the extracellular region, a deletion which includes most of the first of two cysteine-rich sequences, have been observed in multiple human epithelial tumors, including malignant gliomas. These EGFR oncoproteins, designated deltaEGFR or EGFRvIII, confer increased tumorigenicity in vivo and are often coexpressed with full-length EGFR in human tumors. We have expressed an ectodomain-derived, carboxyl-terminal deletion mutant of the p185neu oncogene (T691stop) in human glioblastoma cells coexpressing endogenous EGFR and activated deltaEGFR oncoproteins. The p185neu ectodomain-derived mutant forms heterodimers with deltaEGFR proteins and reduces the phosphotyrosine content and kinase activity of deltaEGFR monomers. As a consequence of T691stop neu expression and surface localization, cell proliferation in conditions of full growth and reduced serum and anchorage-independent growth in soft agar was reduced in glioblastoma cells expressing either endogenous EGFR alone or coexpressing EGFR and elevated levels of deltaEGFRs. T691stop neu mutant receptors abrogate the dramatic growth advantage conferred by deltaEGFR in vivo, suggesting that physical associations primarily between subdomains III and IV of the p185neu and EGFR ectodomains are sufficient to modulate signaling from activated EGFR complexes. Receptor-based inhibitory strategies exploit the thermodynamic preference for erbB ectodomains to heterodimerize, thereby creating erbB receptor assemblies which are defective in signaling and do not internalize. Pharmaceuticals which mimic the p185neu ectodomain may therefore have important therapeutic applications in advanced human malignancies expressing erbB receptors.

N terminus of Sos1 Ras exchange factor: critical roles for the Dbl and pleckstrin homology domains

We have studied the functional importance of the N terminus of mouse Sos1 (mSos1), a ubiquitously expressed Ras-specific guanine nucleotide exchange factor whose C-terminal sequences bind Grb-2. Consistent with previous reports, addition of a myristoylation signal to mSos1 (MyrSos1) rendered it transforming for NIH 3T3 cells and deletion of the mSos C terminus (MyrSos1-deltaC) did not interfere with this activity. However, an N-terminally deleted myristoylated mSos1 protein (MyrSos1-deltaN) was transformation defective, although the protein was stable and localized to the membrane. Site-directed mutagenesis was used to examine the role of the Dbl and pleckstrin homology (PH) domains located in the N terminus. When mutations in the PH domain were introduced into two conserved amino acids either singly or together in MyrSos1 or MyrSos1-deltaC, the transforming activity was severely impaired. An analogous reduction in biological activity was seen when a cluster of point mutations was engineered into the Dbl domain. The mitogen-activation protein (MAP) kinase activities induced by the various Dbl and PH mutants of MyrSos1 correlated with their biological activities. When NIH 3T3 cells were transfected with a myristoylated Sos N terminus, their growth response to epidermal growth factor (EGF), platelet-derived growth factor, lysophosphatidic acid or serum was greatly impaired. The dominant inhibitory biological activity of the N terminus correlated with its ability to impair EGF-dependent activation of GTP-Ras and of MAP kinase, as well with the ability of endogenous Sos to form a stable complex with activated EGF receptors. The N terminus with mutations in the Dbl and PH domains was much less inhibitory in these biological and biochemical assays. In contrast to wild-type Sos1, nonmyristoylated versions of Sos1-deltaN and Sos1-deltaC did not form a stable complex with activated EGF receptors. We conclude that the Dbl and PH domains are critical for Sos function and that stable association of Sos with activated EGF receptors requires both the Sos N and C termini.

Molecular characterization of type E Clostridium botulinum and comparison to other types of Clostridium botulinum

Determination of nucleotide sequence upstream to the neurotoxin binding protein (NBP) gene of type E Clostridium botulinum has revealed an open reading frame whose stop codon is only 18 bp apart from the start codon of the NBP gene. Amino acid sequence derived from the corresponding nucleotide sequence suggested the existence of the open reading frame as a 47.8 kDa protein (P-48). Protein data bank search revealed that the 47.8 kDa protein has 80% sequence identity to P-47 of type F C. botulinum. The gene organization of type E. Clostridium botulinum was predicted and compared to other types of C. botulinum. In type E C. botulinum, genes for the P-48, the neurotoxin binding protein and the neurotoxin form an operon which was similar to that of type F C. botulinum. However, type E C. botulinum has a P-18 gene instead of P-21 gene observed in type F C. botulinum, both located upstream to their respective P-48/P-47 gene.

Identification of p185neu sequences required for monoclonal antibody- or ligand-mediated receptor signal attenuation

Anti-p185neu antibodies downmodulate constitutively active p185neu receptors from the cell surface, which is associated with a reduction in the transformed phenotype. We have analyzed a group of mutant p185neu forms with carboxyl (C)-terminal truncations and/or an internal deletion of amino acids 1008-1057. Receptor endocytosis and degradation were examined by flow cytometric analysis and pulse-chase assays following anti-p185neu monoclonal antibody (MAb) treatment. Deletion of a sequence within the distal carboxyl terminus, including three known autophosphorylation sites, did not affect MAb-mediated receptor surface downmodulation and degradation of surface receptor. However, kinase-active deletion mutants with elimination of the putative internalization sequence (Tint delta), or Tint delta mutants also containing a large C-terminal truncation, displayed markedly impaired receptor endocytosis in response to MAb treatment. Cells expressing endocytosis-defective mutant proteins became insensitive to anti-p185neu MAb-mediated inhibition of anchorage-independent growth and were more oncogenic in vivo. Cells expressing endocytosis-defective mutant EGFR/neu chimeric proteins were more transforming upon EGF addition when compared to cells expressing wild-type EGFR/neu receptors. Taken together, these data suggest that, in addition to kinase activity, p185neu receptor endocytosis requires a functional modular structure, i.e., an internalization sequence, possibly to serve as target for endocytotic adapter proteins. Unattenuated signaling from oncogenic p185neu forms resulting from prolonged surface localization may result in enhanced cellular transformation and desensitization to MAb-mediated downregulation and phenotypic reversion.

Molecular characterization and in situ localization of a mouse retinal taurine transporter

Various ocular tissues have a higher concentration of taurine than plasma. This taurine concentration gradient across the cell membrane is maintained by a high-affinity taurine transporter. To understand the physiological role of the taurine transporter in the retina, we cloned a taurine transporter encoding cDNA from a mouse retinal library, determined its biochemical and pharmacological properties, and identified the specific cellular sites expressing the taurine transporter mRNA. The deduced protein sequence of the mouse retinal taurine transporter (mTAUT) revealed >93% sequence identity to the canine kidney, rat brain, mouse brain, and human placental taurine transporters. Our data suggest that the mTAUT and the mouse brain taurine transporter may be variants of one another. The mTAUT synthetic RNA induced Na+- and Cl(-)-dependent [3H]taurine transport activity in Xenopus laevis oocytes that saturated with an average Km of 13.2 microM for taurine. Unlike the previous studies, we determined the rate of taurine uptake as the external concentration of Cl- was varied, a single saturation process with an average apparent equilibrium constant (K(Cl-)) of 17.7 mM. In contrast, the rate of taurine uptake showed a sigmoidal dependence when the external concentration of Na+ was varied (apparent equilibrium constant, K(Na+) approximately 54.8 mM). Analyses of the Na+- and Cl(-)-concentration dependence data suggest that at least two Na+ and one Cl- are required to transport one taurine molecule via the taurine transporter. Varying the pH of the transport buffer also affected the rate of taurine uptake; the rate showed a minimum between pH 6.0 and 6.5 and a maximum between pH 7.5 and 8.0. The taurine transport was inhibited by various inhibitors tested with the following order of potency: hypotaurine > beta-alanine > L-diaminopropionic acid > guanidinoethane sulfonate > beta-guanidinopropionic acid > chloroquine > gamma-aminobutyric acid > 3-amino-1-propanesulfonic acid (homotaurine). Furthermore, the mTAUT activity was not inhibited by the inactive phorbol ester 4alpha-phorbol 12,13-didecanoate but was inhibited significantly by the active phorbol ester phorbol 12-myristate 13-acetate, which was both concentration and time dependent. The cellular sites expressing the taurine transporter mRNA in the mouse eye, as determined by in situ hybridization technique, showed low levels of expression in many of the ocular tissues, specifically the retina and the retinal pigment epithelium. Unexpectedly, the highest expression levels of taurine transporter mRNA were found instead in the ciliary body of the mouse eye.

Inflammation modulates in vitro colonic myoelectric and contractile activity and interstitial cells of Cajal

Inflammation suppresses phasic contractile activity in vivo. We investigated whether inflammation also suppresses in vitro phasic contractile activity and, if so, whether this could in part be due to the alteration of specific slow wave characteristics and morphology of the interstitial cells of Cajal (ICC). Circular muscle strips were obtained from normal and inflamed distal canine colon. Inflammation was induced by mucosal exposure to ethanol and acetic acid. The amplitudes of spontaneous, methacholine-induced, substance P-induced, and electrical field stimulation-induced contractions were smaller in inflamed muscle strips than in normal muscle strips. Inflammation reduced the resting membrane potential and the amplitude and duration of slow waves in circular muscle cells. Inflammation did not affect the amplitude of inhibitory junction potentials but did decrease their duration. Ultrastructural studies showed expansion of the extracellular space between circular muscle cells, reduction in the density of ICC and associated neural structures, damage to ICC processes, vacuolization of their cytoplasm, and blebbings of the plasma membrane. We conclude that inflammation-induced alterations of slow wave characteristics contribute to the suppression of phasic contractions. These alterations may, in part, be due to the damage to ICC. Inflammation impairs both the myogenic and neural regulation of phasic contractions.

Elimination of established murine colon carcinoma metastases by antibody-interleukin 2 fusion protein therapy

A recombinant humanized antibody-interleukin 2 fusion protein (huKS1/4-IL-2) was used to direct IL-2 to the tumor microenvironment and elicit a T cell-mediated eradication of established pulmonary and hepatic CT26-KSA colon carcinoma metastases in syngeneic BALB/c mice. This antitumor effect was specific because a fusion protein, which was nonreactive with these tumor cells, failed to exert any such effect. The efficacy of the huKS1/4-IL-2 fusion protein in eliminating metastases was documented because mixtures of monoclonal antibody huKS1/4 with recombinant human IL-2 were ineffective and, at best, only partially reduced tumor load. Two lines of evidence indicated the eradication of metastases and the absence of minimal residual disease in animals treated with the fusion protein: first, the lack of detection of CT26-KSA cells by reverse transcription-PCR, which can detect one tumor cell in 10(6) liver cells; and second, the tripling of life span. The effector mechanism involved in this tumor eradication is dependent on T cells because the IL-2-directed therapy is ineffective in T cell-deficient SCID mice. The essential effector cells were further characterized as CD8+ T cells by in vivo depletion studies. Such T cells, isolated from tumor-bearing mice after fusion protein therapy, elicited MHC class I-restricted cytotoxicity in vitro against colon carcinoma target cells. Taken together, these data indicate that fusion protein-directed IL-2 therapy induces a T cell-dependent host immune response capable of eradicating established colon cancer metastases in an animal tumor model.

Endogenous regulation of angiogenesis in the rat aorta model. Role of vascular endothelial growth factor

The purpose of this study was to investigate the role of vascular endothelial growth factor (VEGF) in the rat aorta model of angiogenesis. Freshly cut aortic rings generated microvascular outgrowths in serum-free collagen gel culture. Angiogenesis was reduced to 10% when the explants were embedded in collagen 10 to 14 days after excision from the animal. Immunochemical studies of conditioned medium demonstrated secretion of VEGF by the aortic cultures. Levels of VEGF decreased during the second week of culture when the explants became quiescent and microvessels stopped growing. Treatment of quiescent aortic rings with exogenous VEGF stimulated angiogenesis and restored microvascular growth to values observed in cultures of freshly cut explants. Reverse transcriptase polymerase chain reaction of vasoformative collagen gel cultures of rat aorta demonstrated the expression of the alternatively spliced isoforms VEGF165, VEGF189, and the high affinity VEGF receptor flk-1. Reverse transcriptase-polymerase chain reaction of rat aorta-derived cell strains confirmed the presence of VEGF165 and VEGF189 in endothelial cells, smooth muscle cells, and fibroblasts. The flk-1 receptor was expressed by endothelial cells but not by fibroblasts or smooth muscle cells, which is consistent with the endothelial target specificity of VEGF. The spontaneous angiogenic response of freshly cut aortic rings was inhibited by 70% with a neutralizing antibody against VEGF, whereas nonimmune IgG had no effect (P < 0.001). These findings provide evidence for a VEGF-mediated autocrine/paracrine regulation of angiogenesis in the rat aorta model.

[Purification and properties of inulinase from Aspergillus niger]

The main component of inulinase was purified from fermentation broth of Aspergillus niger 319 to homogeneity by using ammonium sulfate fraction, ion-exchange chromatography on DEAE-cellulose column and Sephadex G-100 gel filtration. The specific activity was as 67 folds at the fermentation broth, and the yield was 25.5%. The inulinase, containing 13.92% of carbohydrate, was a monomer protein with a molecular weight of 28,000 Dalton; and its isoelectric point was pH 5.4. The optimal pH and temperature of the inulinase was pH 5.0 and 60 degrees C, respectively. The enzyme was strongly inhibited by heavy metal ions of Hg2+, Pb2+ and Cu2+. The optimal substrate for the enzyme was inulin and the product was only fructose, but it also had invertase activity with the I/S of 0.348. The Km and Vm of the inulinase was 6.25 mmol/L and 67.11 mumol.mg-1.min-1, respectively.

Thrombospondin-1 modulates angiogenesis in vitro by up-regulation of matrix metalloproteinase-9 in endothelial cells

Evidence suggests that thrombospondin-1 (TSP-1), a 450-kDa glycoprotein in platelets and extracellular matrix, is involved in angiogenesis. However, the mechanisms by which TSP-1 regulates angiogenesis are unknown, and the exact role of TSP-1 in angiogenesis has been controversial: both stimulatory and inhibitory effects of TSP-1 have been reported. In this study, we evaluated the effect of TSP-1 on the capacity of bovine aortic endothelial (BAE) cells to both invade and form microvessel-like tubes in collagen gels. BAE cell tube formation was enhanced by exogenous TSP-1 at relatively low concentrations (1-10 microg/ml) but inhibited at higher concentrations of TSP-1 (>15 microg/ml). In addition, we correlated this biphasic effect on tube formation with the capacity of TSP-1 to stimulate the activity of a matrix metalloproteinase-9 (MMP-9) in BAE cell collagen gel cultures. The TSP-1-mediated stimulation of MMP-9 activity was specific and dose- and time-dependent. Furthermore, TSP-1-stimulated BAE cell invasion and tube formation were reversed by antibodies against both TSP-1 and MMP-9, suggesting that TSP-1 modulates endothelial cell invasion and morphogenesis in vitro by a mechanism involving the regulation of MMP-9 activity. These findings support the conclusion that TSP-1 is a multifunctional modulator of angiogenesis and are consistent with the dynamic presence of TSP-1 in remodeling tissues in which matrix degradation is required.

Allosteric activation of phosphatidylinositol-specific phospholipase C: specific phospholipid binding anchors the enzyme to the interface

Phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis exhibits 'interfacial activation' toward the water-soluble substrate myo-inositol 1,2-(cyclic)phosphate [Zhou et al. (1997) Biochemistry 36, 347-355]. The activation of PI-PLC enzyme is optimal with PC or PE interfaces. NMR experiments (TRNOE and 31P line width analyses) were carried out to investigate the interaction of PI-PLC with activator amphiphiles. These studies showed that the enzyme had high affinity for phosphatidylcholine (or PE) molecules with dissociation constants of 0.5 and 0.3 mM for diC6PC and diC7PC, respectively. TRNOE cross-peaks of bound PC were confirmed to represent intramolecular relaxation pathways using partially perdeuterated PC molecules consistent with a single molecule binding tightly. The large activation by a PC interface can be explained by a single PC molecule binding specifically to PI-PLC and anchoring the enzyme-lipid complex to the interface. Other interfaces, such as micellar diC8PS, can activate PI-PLC about 2-3-fold; however, the monomers of these detergents showed little affinity for the enzyme as measured by TRNOE or 31P NMR line widths. The 3.6-fold activation produced by polymerized vesicles of 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphocholine (compared to the 15-fold activation generated by nonpolymerized PC vesicles) was comparable to the nonspecific activation of other detergents. This confirmed that single-PC molecule binding was allosteric and anchored the enzyme in the interface. The conformation of interfacially activated enzyme is discussed in term of the stabilization of a critical surface loop and helix B observed with weak intensity in the X-ray crystal structure.

Transforming growth factor-beta, transforming growth factor-beta receptor II, and p27Kip1 expression in nontumorous and neoplastic human pituitaries

Transforming growth factor (TGF)-beta has been implicated in the regulation of normal and neoplastic anterior pituitary cell function. TGF-beta regulates the expression of various proteins, including p27Kip1 (p27), a cell cycle inhibitory protein. We examined TGF-beta, TGF-beta type II receptor (TGF-beta-RII), and p27 expression in normal pituitaries, pituitary adenomas, and carcinomas to analyze the possible roles of these proteins in pituitary tumorigenesis. Normal pituitary, pituitary adenomas, and pituitary carcinomas all expressed TGF-beta and TGF-beta-RII immunoreactivity. Reverse transcription polymerase chain reaction analysis showed TGF-beta 1, -beta 2, and -beta 3 isoforms and TGF-beta-RII in normal pituitaries and pituitary adenomas. Pituitary adenomas cells cultured for 7 days in defined media showed a biphasic response to TGF-beta with significant inhibition of follicle-stimulating hormone secretion at higher concentrations (10(-9) mol/L) and stimulation of follicle-stimulating hormone secretion at lower concentrations (10(-13) mol/L) of TGF-beta 1 in gonadotroph adenomas. Immunohistochemical analysis for p27 protein expression showed the highest levels in nontumorous pituitaries with decreased immunoreactivity in adenomas and carcinomas. When nontumorous pituitaries and various adenomas were analyzed for p27 and specific hormone production, growth hormone, luteinizing hormone, and thyroid-stimulating hormone cells and tumors had the highest percentages of cells expressing p27, whereas adrenocorticotrophic hormone cells and tumors had the lowest percentages. Immunoblotting analysis showed that adrenocorticotrophic hormone adenomas also had the lowest levels of p27 protein. Semiquantitative reverse transcription polymerase chain reaction and Northern hybridization analysis did not show significant differences in p27 mRNA expression in the various types of adenomas or in nontumorous pituitaries. In situ hybridization for p27 mRNA showed similar distributions of the gene product in nontumorous pituitaries, pituitary adenomas, and carcinomas. These results indicate that TGF-beta and TGF-beta-RII are widely expressed in nontumorous pituitaries and in pituitary neoplasms and that TGF-beta 1 regulates pituitary hormone secretion. The levels of the TGF-beta-regulated protein p27 decreases in the progression of normal to neoplastic pituitaries. In contrast, the mRNA levels of p27 remained relatively constant in nontumorous pituitaries, pituitary adenomas, and carcinomas, indicating that p27 protein levels in adenomas and carcinomas are regulated by translational and post-translational mechanisms.

Two distinct TATA-less promoters direct tissue-specific expression of the rat apo-B editing catalytic polypeptide 1 gene

The species and tissue specificity of apolipoprotein (apo) B mRNA editing is determined by the expression of apoB editing catalytic polypeptide 1 (APOBEC-1), the cytidine deaminase that catalyzes apoB mRNA editing. To understand the molecular mechanisms that regulate the transcription of APOBEC-1, we characterized rat APOBEC-1 cDNA and genomic DNA. cDNA cloning and RNase protection analysis showed two alternative promoters for the tissue-specific expression of APOBEC-1 in the liver and intestine, Pliv and Pint. Both promoters lack a TATA box, and Pint belongs to the MED-1 class of promoters, which initiate transcription at multiple sites. We also identified two allelic forms of the APOBEC-1 gene from the characterization of two rat APOBEC-1 P1 genomic clones, RE4 and RE5. The RE4 allele is 18 kilobases long and contains six exons and five introns, whereas the RE5 allele contains an additional approximately 8 kilobases of intron sequences and an extra exon encoding a 5'-untranslated region; however, the APOBEC-1 transcripts from the two alleles appear to have similar, if not identical, functions. Transgenic mouse studies showed that Pliv was preferentially used in the liver, kidney, brain, and adipose tissues, whereas Pint was preferentially used in the small intestine, stomach, and lung. Our results suggest that the tissue-specific expression of APOBEC-1 is governed by multiple regulatory elements exerting control over a single coding sequence. The presence or absence of these regulatory elements may determine the tissue-specific expression of APOBEC-1 in other mammalian species.

Gonadotropin-releasing hormone and gonadotropin-releasing hormone receptor messenger ribonucleic acids expression in nontumorous and neoplastic pituitaries

In the nontumorous pituitary, GnRH stimulates the release and synthesis of LH and FSH by gonadotroph cells via the GnRH receptor (GnRH-R). Little is known, however, about expression of GnRH and GnRH-R messenger RNAs (mRNAs) in nontumorous pituitary tissue and in adenomas. To learn more about the distribution and regulatory roles of GnRH and its receptor, we investigated the expression of both GnRH and GnRH-R mRNAs in nontumorous human pituitary and in various types of pituitary adenomas using the RT-PCR, in situ hybridization, and in situ hybridization in combination with RT-PCR (in situ RT-PCR). Using RT-PCR, GnRH mRNA was found to be expressed in normal human pituitaries and in all types of adenomas. Similarly, GnRH-R mRNA was expressed in nontumorous human pituitaries and in most, but not all, adenomas. These included 5 gonadotroph adenomas, 6 null cell adenomas, 1 of 2 GH-producing tumors, and 1 of 2 ACTH-producing adenomas, but not in the 2 PRL-producing adenomas examined. In situ hybridization studies showed GnRH and GnRH-R mRNAs in all 3 nontumorous pituitaries and in 12 of 33 (36.4%) and 10 of 33 adenomas (30.3%), respectively. Using an indirect in situ RT-PCR technique to increase the sensitivity of the in situ localization, GnRH and GnRH-R mRNAs were detected in 29 (87.9%) and 25 (75.8%) of 33 adenomas, respectively. This is the first report of the localization of GnRH and GnRH-R mRNAs in individual pituitary adenoma cells using in situ RT-PCR. The frequent expression of GnRH and GnRH-R mRNAs in pituitary cells suggests that GnRH has autocrine/paracrine functions in nontumorous and neoplastic pituitary tissues.

Trans receptor inhibition of human glioblastoma cells by erbB family ectodomains

Our aim has been to understand the features of erbB receptor homo- and heterodimer assembly to develop approaches to disrupt receptor activation. We have developed a general approach to cause erbB receptor-specific trans inhibition of human neoplasia. The clonal progression of human astrocytomas to a more malignant phenotype often involves the amplification and overexpression of the epidermal growth factor receptor (EGFr) gene. We have selectively targeted the EGFr in human glioblastoma cells with kinase-deficient mutants of the erbB family derived from the ectodomain of the Neu oncogene that are able to form heterodimers with EGFr and inhibit EGFr-dependent phenotypes. In EGFr-positive U87MG human glioblastoma cells, expression of the Neu ectodomain inhibits EGF-, but not platelet-derived growth factor-, induced DNA synthesis; inhibits cell proliferation in the presence of EGF, but not platelet-derived growth factor; inhibits the ability of U87MG to form colonies in soft agar; and inhibits transforming efficiency in athymic mice. These studies establish that EGFr-mediated signal transduction is important in the maintenance of malignant glioma, and that trans receptor inhibition is a novel way to abrogate abnormal growth of these tumors. Neu ectodomains will be useful in determining the manner in which the EGFr contributes to glial tumorigenesis and in the design of pharmaceuticals that disable erbB family oncoproteins. In addition, these studies provide a rationale for the application of the Neu ectodomain in gene therapy approaches to human malignant glioma and, potentially, to other systemic epithelial malignancies expressing erbB family receptors.

[Analysis of PTH amino acids by micellar electrokinetic capillary chromatography]

A useful method for separation of 19 PTH amino acids by micellar electrokinetic capillary chromatography has been developed. Experiments were performed at 35 degrees C with 14kV power, 50microm x 57cm fused-silica capillary column and UV absorption detector. Each new capillary was washed with 0.1mol/L NaOH and deionized water, each for 15min, before use. Samples were injected into the capillary by applying pressure (3402Pa) for 5s. Absorption detection was at 200nm. The running buffer was made up of 50mmol/L sodium dodecyl sulfate (SDS), 50mmol/L sodium of phosphate and borate (pH 7. 0). The infulence of operation voltage, pH of buffer, temperature and SDS concentration on the amino acids migration has been studied. The coefficients of variaton of migration time and peak area of 19 PTH amino acids were below 1.0% and 5.0% respectively. The detection limits were 0.1-0.25pmol.

Prolactin receptor messenger ribonucleic acid in normal and neoplastic human pituitary tissues

We examined the specific cell types in normal human pituitaries that expressed PRL receptor (PRL-R) messenger ribonucleic acid (mRNA) by combined in situ hybridization and immunohistochemistry. The distribution of PRL-R mRNA in 28 pituitary adenomas was examined by in situ hybridization and reverse transcription-PCR in 12 cases of adenomas. In another set of experiments, 34 PRL adenomas from men, women, and bromocriptine-treated patients were analyzed for PRL-R by in situ hybridization. In the normal pituitary, PRL- and LH-producing cells had significantly more mean grain counts per cell and higher percentages of cells positive for PRL-R than GH and TSH cells. PRL-R mRNA was present in all groups of adenomas by in situ hybridization and reverse transcription-PCR. PRL adenomas had a significantly higher density of labeling compared to other adenoma types. Although there was no difference in the levels of PRL-R mRNA in PRL adenomas from men and premenopausal and postmenopausal women, patients treated with bromocriptine before pituitary surgery had significantly lower levels of PRL-R compared to all other groups. These results indicate that in the normal pituitary, PRL and LH cells have the highest level of PRL-R mRNA, whereas PRL adenomas have significantly higher levels of PRL-R mRNA than other types of adenomas, and bromocriptine treatment decreases the levels of PRL-R mRNA in PRL adenomas.

Aberrant p27kip1 expression in endocrine and other tumors

The p27kip1 (p27) gene encodes an inhibitor of cyclin-dependent kinase activity. The expression of p27 protein in normal and neoplastic tissues was investigated by immunoblotting and immunohistochemistry. Immunoblotting studies detected a 27-kd protein band that was decreased in neoplastic pituitary tissues compared with normal pituitary. Immunostaining of 177 tissues showed abundant expression of p27 protein in normal tissues with decreased numbers of immunoreactive cells in adenomas and carcinomas in both endocrine and nonendocrine tissues. p27 expression was inversely related to the proliferation marker Ki-67 antigen detected with monoclonal antibody MIB-1. Parathyroid adenomas and hyperplasias had similar Ki-67 labeling indices; however, hyperplasias had threefold more p27-positive cells than parathyroid adenomas, suggesting that p27 immunostaining may be useful in distinguishing between these two conditions. These results indicate that there is widespread aberrant p27 expression in hyperplastic tissues and in benign and malignant neoplasms compared with normal tissues. Immunohistochemical analysis of p27 along with Ki-67 may be used to assess the biological behavior of various neoplasms, to classify hyperplastic and neoplastic tissues, and to study cell cycle regulation during tumor progression.

Tactile pattern perception by two fingers: temporal interference and response competition

The identification of a spatial pattern (target) presented to one fingerpad may be interfered with by the presentation of a second pattern (nontarget) to either the same fingerpad or a second fingerpad. A portion of the interference appears to be due to masking and a portion to response competition. In the present study, vibrotactile spatial patterns were designed to extend over two fingerpads. Target and nontarget patterns were presented to the same two fingerpads with a temporal separation between the two patterns. The function relating target identification to the temporal separation between the target and nontarget was very similar to the functions obtained with one-finger patterns in temporal masking studies. Subsequent measurements showed that a substantial portion of the interference resulted from response competition. Pattern categorization was better when patterns were presented to two fingers on opposite hands than to two fingers on the same hand; however, there was more interference for patterns presented bilaterally than for patterns presented ipsilaterally. The results supported the conclusion that similar processes are involved in the perception of sequences of spatial patterns whether the patterns are presented to one or to two fingers.

Percutaneous transluminal coronary angioplasty for acute myocardial infarction: initial experience in 43 cases

OBJECTIVE

To evaluate the initial experience with the use of percutaneous transluminal coronary angioplasty (PTCA) in the set of acute myocardial infarction (AMI).

METHODS

Between October 1993 and April 1996, PTCA was performed in 43 patients (34 male, 9 female) with initial onset of AMI. These patients ranged in age from 40 to 74 years (mean +/- SD, 60.3 3 +/- 9.2). Primary PTCA was performed in 16, rescue PTCA in 8, and semi-elective PTCA in 19 patients.

RESULTS

The initial success was achieved in 95.3% (41/ 43). Failed angioplasty occurred in 2 patients, with acute reocclusion after rescue PTCA (this patient died of cerebral stroke 3 days later) in one patient, and small local intimal dissection during semi-elective PTCA in another patient.

CONCLUSION

PTCA was a safe and effective approach in the treatment of AMI in the present study patients, with a high primary success and low acute complication rate.

FGF2 concentration regulates the generation of neurons and glia from multipotent cortical stem cells

The embryonic cerebral cortex contains a population of stem-like founder cells capable of generating large, mixed clones of neurons and glia in vitro. We report that the default state of early cortical stem cells is neuronal, and that stem cells are heterogeneous in the number of neurons that they generate. In low fibroblast growth factor (FGF2) concentrations, most maintain this specification, generating solely neuronal progeny. Oligodendroglial production within these clones is stimulated by a higher, threshold level of FGF2, and astrocyte production requires additional environmental factors. Because most cortical neurons are born before glia in vivo, these data support a model in which the scheduled production of cortical cells involves an intrinsic neuronal program in the early stem cells and exposure to environmental, glia-inducing signals.

C2-symmetrical tetrahydroxyazepanes as inhibitors of glycosidases and HIV/FIV proteases

C2-Symmetrical tetrahydroxyazepanes were synthesized as inhibitors for glycosidases. Tetrahydroxyazepane 1 is a non-specific inhibitor of various glycosidases, while compounds 2, 3 and 4 specifically inhibit beta-N-acetylglucosaminidase, beta-glucosidase, and alpha-fucosidase, respectively, with Ki in the micromolar range. Compound 1 is not an inhibitor of HIV/FIV proteases, but its 3,6-difluorobenzyl derivatives are moderate inhibitors of both enzymes.

Inhibition of p185neu kinase activity and cellular transformation by co-expression of a truncated neu protein

The rat neu oncogene product encodes a 185 kDa receptor tyrosine kinase which is constitutively activated as a result of a single amino acid substitution (Val664-->Glu) within the transmembrane region. In this study, we show that the transforming activity of oncogenic p185neu (also termed Tneu) can be inhibited by co-expression of a truncated neu protein with a large cytoplasmic deletion (termed T691stop) which includes the tyrosine kinase domain. In cell lines co-expressing full-length and truncated neu proteins, we observed co-dimerization between full-length p185neu and truncated T691 stop, resulting in the formation of a kinase-inactive heteromeric complex. Phenotypic analysis of several different clones showed that the degree of inhibition of transformation in vitro and tumorigenicity in vivo was related to the ratio of full-length and truncated p185 proteins co-expressed in cells. These results provide evidence that expression of kinase-deficient neu proteins leads to co-dimerization that results in suppression of kinase activation and oncogenicity of associated p185neu-activated receptors. The mutant neu protein mediates inhibition in both transfected fibroblasts expressing oncogenic p185neu and mammalian cancer cells derived from a rat primary neuroglioblastoma expressing oncogenic p185neu. This truncated peptide may be important for the design of future therapies directed against erbB family oncoproteins.

Long-term oral administration of L-arginine enhances endothelium-dependent vasorelaxation and inhibits neointimal thickening after endothelial denudation in rats

OBJECTIVE

To further prove the hypothesis that local decrease of nitric oxide (NO) synthesis and/or its activity might be critically important in the disturbance of vascular homeostasis after vascular injuries.

METHODS

Intimal thickening model induced by air-drying denudation of rat right common carotid artery was performed to evaluate the effects of long-term oral administration of L-arginine on neointimal thickening and acetylcholine-induced endothelium-dependent vasorelaxation (EDR) by histomorphometric and functional studies.

RESULTS

Reductions in EDR function persisted and simultaneously developed prominent neointimal thickening by 14 days after denudation. Long-term oral supplementation of L-arginine (1 g/kg/day) significantly enhanced EDR from 43.5% +/- 12.35% to 68.8% +/- 9.0% (n = 10, P < 0.001) and reduced neointimal thickening from 62.45 microns +/- 11.26 microns to 21.45 microns +/- 6.34 microns (n = 10, P < 0.001) as compared with each control animals.

CONCLUSIONS

This study shows that oral administration of L-arginine significantly inhibits neointimal thickening and preserves NO-mediated EDR in experimental endothelial denudation, suggesting an important role for L-arginine, NO pathway in the regulation of vascular homeostasis after endothelial injury which might be salutary in prevention restenosis after coronary angioplasty.

Expression of thrombospondin-1 in cancer: a role in tumor progression

Thrombospondin-1 (TSP-1), a trimeric high molecular weight glycoprotein, is one of the major secreted proteins of human platelets and an extracellular matrix component of a variety of cells including vascular endothelial cells and tumor cells. TSP-1 has been shown to be highly expressed in human malignant tissues and present in higher than normal levels in the plasma of cancer patients. TSP-1 has also been shown to promote hematogenous tumor spread, tumor cell adhesion and invasion, and angiogenesis. Overall these studies provide compelling evidence for the conclusion that TSP-1 plays an important role in tumor progression.

Transforming growth factor-beta and p27 expression in pituitary cells

Transforming growth factor-beta (TGF beta) is a member of a family of growth factors that regulates differentiation and cellular proliferation in a wide variety of tissues, including the anterior pituitary gland. TGF beta regulates the expression of various proteins, including p27Kipl (p27), a cell cycle inhibitory protein. The cell types in normal rat anterior pituitary producing TGF beta1, one of the principal isoforms of TGF beta, and p27 were examined by in situ methods. The regulation of p27 messenger RNA (mRNA) and protein by TGF beta1 was also examined in cultured anterior pituitary cells. In situ hybridization, in situ reverse transcriptase PCR, and immunocytochemical staining for pituitary hormones showed that PRL, TSH, and gonadotroph cells all had a higher percentage of cells expressing TGF beta1 mRNA and p27 protein than did GH and ACTH cells. After treatment with 10(-9) M TGF beta1 in vitro for 3 days, there were significant decreases in p27 mRNA and protein levels (P < 0.05) in normal pituitary cells. The GH3 and GHRH-CL1 cell lines, which secrete PRL and GH, had undetectable p27 protein by immunocytochemical staining and immunoblotting, although the GH3 cell line had p27 mRNA detected by reverse transcriptase PCR. Analysis of [3H]thymidine uptake in cultured dissociated pituitary cells by double staining for hormones showed that only PRL cells had significant proliferative activity during a 3-day cell culture period. There was a biphasic effect of TGF beta1 on PRL cell proliferation, with marked inhibition by 10(-9) M and a slight stimulation by 10(-13) M. These results indicate that there is a differential distribution of both TGF beta1 and p27 in various anterior pituitary cell types and that TGF beta1 directly down-regulates p27 in cultured anterior pituitary cells.

Thrombospondin-1 (TSP-1) promotes the invasive properties of human breast cancer

TSP-1 is a matrix-bound adhesive glycoprotein, which plays a role in tumor cell proliferation and tumor angiogenesis. The purpose of this study was to investigate the effect of TSP-1 on breast tumor cell invasion. Tumor cell invasion assays were performed using a modified Boyden chamber apparatus with collagen-coated membranes. Four breast cell lines were studied in serum-free media: the malignant MDA-MB-231, SKBR-3, and MCF-7 cell lines, and the benign MCF-10A cell line. Invasion was measured as the summation of the number of cells in five representative high power fields (400x) traversing the collagen barrier after a 3-hr incubation period. The effect of an anti-TSP-1 antibody (100 microgram/ml) was also evaluated in the malignant cell lines. Statistical analysis was performed by ANOVA and Student's unpaired t test. TSP-1 promoted a dose-dependent increase in invasion as compared to buffer controls in all three malignant cell lines. TSP-1 (100 nM) promoted a greater than five-fold increase over controls in tumor cell invasion for MDA-MB-231, SKBR-3, and MCF-7 cell lines (P < 0.005). TSP-1 had no effect on the invasiveness of the benign cell type MCF-10A. Anti-TSP-1 antibody inhibited TSP-1 promoted invasion in the MDA-MB-231, SKBR-3, and MCF-7 cell lines by 45, 48, and 39%, respectively (P = 0.003, 0.044, 0.047). TSP-1 promotes tumor cell invasion of collagen by breast cancer cells. Therapy designed to inhibit TSP-1 may prevent invasion and metastasis in breast cancer.

Epidermal growth factor in acute promyelocytic leukemia treated with retinoic acid

We studied 18 patients with acute promyelocytic leukaemia and 13 with relapsed APL. We found a significantly elevated EGF in acute leukaemia, especially in APL, being 418.59 +/- 19.2 micrograms in the 24-h urine that was much higher than that of the normal controls. When eight APL patients achieved complete remission by RA treatment, the EGF value decreased to 149.9 +/- 27.3 micrograms in the 24-h urine near to normal. In 13 patients with relapsed APL, EGF rose to 446.9 +/- 82.6 micrograms in the 24-h urine. Most interestingly, this elevated EGF could be detected before the relapse by 5 +/- 0.84 months in seven out of eight APL with relapse. We suggest that the unaccountably elevated EGF during remission period may be an indicator of the occurrence of relapse.

Detection of PML-RAR alpha in patients with APL during follow-up period

OBJECTIVE

To evaluate the significance of PML-RAR alpha transcripts in patients with acute promyelocytic leukemia (APL) during remission period and to follow up the patients through monitoring aberrant gene expression.

PATIENTS AND METHODS

This study included 17 patients with APL (5 females and 12 males). Another 19 APL patients during relapse served as control. RNA extraction was obtained through the single-step method. By means of reverse transcriptase polymerase chain reaction (PCR), the PML-RAR alpha was detected in the sample mRNA.

RESULTS

Nine out of 10 patients with complete remission (CR) duration shorter than 3 years were positive. Four cases became negative and three remained positive among 7 cases in a long remission of over 3 years. The difference of the positive rate of PML-RAR alpha transcripts between the 2 groups was significant (P < 0.05). Four among 12 positive cases relapsed. No evidence of relapse was present in the 5 negative patients after 9.6 +/- 3.9-month follow-up. Further treatment was therefore given to the 4 positive patients whose treatment was already ceased at that time. By this management they were all in CR during the following 10-month observation.

CONCLUSIONS

RT-PCR detection for PML-RAR alpha transcripts was useful in monitoring MRD and guiding further treatment to obtain a long remission. Persistently positive transcripts were closely associated with the relapse.

Vertebrate neural progenitor cells: subtypes and regulation

Several advances have been made recently in characterizing neural progenitor cells. In vertebrates, multipotential stem cells have been demonstrated in the developing forebrain both in vitro and in vivo, and a class of stem cells has been identified in the adult CNS. Factors that regulate the proliferation and differentiation of subtypes of neural progenitor cells have also been described. In invertebrates, progress has been made in identifying genes involved in neural progenitor cell specification, cell-fate choices and regulation.

Association of signaling proteins with a nonmitogenic heterodimeric complex composed of epidermal growth factor receptor and kinase-inactive p185c-neu

The functional consequences of heterodimer formation between the epidermal growth factor receptor (EGFr) and the p185c-neu receptor tyrosine kinase include increased mitogenic and transformation potencies. To determine the possible alteration of signal transduction pathways resulting from this heteromeric complex, the capacity of several signaling proteins to associate with the heterodimeric receptors has been assayed. The in vivo interaction with the EGFr/p185c-neu heterodimer of several signal transduction proteins, including phospholipase C-gamma 1 (PLC-gamma 1), the p85 subunit of phosphotidylinositol 3-kinase, the ras GTPase activating protein, SHC, NCK, p72RAF, and the tyrosine phosphatase SHPTP2, was measured by coimmunoprecipitation. The binding of these signaling proteins to a complex composed of EGFr and a kinase-inactive form of p185 (p185K757M) was not impaired, even though the mitogenic and transformation activity of this complex had been abrogated. In addition, the EGF-induced phosphorylation of GAP, p85, and PLC-gamma 1 did not correlate with the dominant-negative action of p185K757M on EGFr function. Thus, substrate association and phosphorylation do not correlate stringently with the mitogenic and transforming activity of this receptor complex, suggesting additional pathways or mechanisms vital to EGFr/p185c-neu heterodimeric signaling.

A security mediator for health care information

The TIHI (Trusted Interoperation of Healthcare Information) project addresses a security issue that arises when some information is being shared among collaborating enterprises, although not all enterprise information is sharable. It assumes that protection exists to prevent intrusion by adversaries through secure transmission and firewalls. The TIHI system design provides a gateway, owned by the enterprise security officer, to mediate queries and responses. The latter are typically transmitted via the Internet. The enterprise policy is determined by rules provided to the mediator. We show examples of typical rules. The problem and our solution, although developed in a healthcare context, is equally valid among collaborating enterprises.

[Hemodynamic and renal effects of strong diuretic atrial natriuretic peptide in patients with acute myocardial infarction]

The hemodynamic and renal effects of strong diuretic atrial natriuretic peptide (ANP) were investigated in 12 patients with acute myocardial infarction. Strong diuretic ANP was administered as a bolus injection of 100 micrograms and followed by a continuous infusion of 2 micrograms/kg within 10 minutes into the right atrium via a catheter. We found that strong diuretic ANP induced an increase in cardiac index and stroke volume index. Right atrial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, systemic vascular resistance and pulmonary vascular resistance were decreased after ANP infusion. The maximal responses were observed immediately after the infusion was completed. No significant change of arterial blood pressure and heart rate was observed. Furthermore, strong diuretic ANP also increased the urine volume, urinary sodium, urinary chloride and urinary potassium. These results suggest that strong diuretic ANP infusion may induce significant changes of hemodynamics and may be used to prevent the development of severe circulatory volume overload in patients with AMI.

Identification of a 140 kDa protein of rat presynaptic terminal membranes encompassing the active zones

A polyclonal antiserum raised against the carboxy-terminal 17 amino acids of the rat p185c-neu (anct) reacted with a 140 kDa polypeptide in membranes of synaptosome fractions from neocortex and hippocampus of 11-day-old and adult rats. The same antiserum reacted with a 185 kDa polypeptide in microsome membranes from rat pheochromocytoma cells (PC12). By light microscopic immunocytochemistry, the anct antibodies against the 140 kDa protein were localized in the neuropile of brain, cerebellum and spinal cord of 11-day-old and adult rats. Especially prominent staining was obtained in the CA2-CA3 zones of the hippocampus, and in the substantia gelatinosa in the spinal cord. The finely granular and diffuse pattern of the immunostain was consistent with synaptic localizations. Interestingly, antibodies against the entire endodomain of p185c-neu (a-Bacneu) were localized in granular structures, probably representing axo-somatic and axo-dendritic synapses, on a subset of pyramidal neurons of the CA3 zone. By immunoelectron terminals in the giant mossy fiber type in the CA3 and CA4 regions. The immunolocalization of the anct antibodies was restricted in segments of the presynaptic membrane facing the synaptic cleft which include the active zone. The identify and function of the 140 kDa membrane protein of rat brain presynaptic terminals, detected by the anct antibodies, is unknown. The 140 kDa protein may be related to p185c-neu, a tyrosine kinase, or to other known or unknown kinases.