Protective effect of histidine on iron (II)-induced hydroxyl radical generation in rat hearts

We investigated the efficacy of histidine on iron (II)-induced hydroxyl radical (.OH) generation in extracellular fluid of the rat myocardium using a flexibly mounted microdialysis technique (O system). Rats were anesthetized and a microdialysis probe was implanted in the left ventricular, followed by infusion of sodium salicylate in Ringer's solution (0.5 nmol/microL/min) to detect the generation .OH as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (DHBA). Iron (II) clearly produced a concentration-dependent increase in .OH formation. A positive linear correlation between iron (II) and the formation of 2,3-DHBA (R2 = 0.987) was observed. However, histidine (25 mM) was infused through a microdialysis probe; iron (II) failed to increase the 2,3-DHBA formation obtained. To examine the effect of histidine on ischemia-reperfusion of the myocardium, the heart was subjected to myocardial ischemia for 15 min by occlusion of the left anterior descending coronary artery (LAD). When the heart was reperfused, a marked elevation of the levels of 2,3-DHBA was observed in the heart dialysate. When corresponding experiments were performed with histidine (25 mM)-pretreated animals, histidine prevented the ischemia-reperfusion induced .OH generation trapped as 2,3-DHBA. These results indicate that histidine protects the myocardium against ischemia-reperfusion damage by .OH generation.

The zebrafish bozozok locus encodes Dharma, a homeodomain protein essential for induction of gastrula organizer and dorsoanterior embryonic structures

The dorsal gastrula organizer plays a fundamental role in establishment of the vertebrate axis. We demonstrate that the zebrafish bozozok (boz) locus is required at the blastula stages for formation of the embryonic shield, the equivalent of the gastrula organizer and expression of multiple organizer-specific genes. Furthermore, boz is essential for specification of dorsoanterior embryonic structures, including notochord, prechordal mesendoderm, floor plate and forebrain. We report that boz mutations disrupt the homeobox gene dharma. Overexpression of boz in the extraembryonic yolk syncytial layer of boz mutant embryos is sufficient for normal development of the overlying blastoderm, revealing an involvement of extraembryonic structures in anterior patterning in fish similarly to murine embryos. Epistatic analyses indicate that boz acts downstream of beta-catenin and upstream to TGF-beta signaling or in a parallel pathway. These studies provide genetic evidence for an essential function of a homeodomain protein in beta-catenin-mediated induction of the dorsal gastrula organizer and place boz at the top of a hierarchy of zygotic genes specifying the dorsal midline of a vertebrate embryo.

Characterization of insulin-like growth factor binding protein-3 (IGFBP-3) binding to human breast cancer cells: kinetics of IGFBP-3 binding and identification of receptor binding domain on the IGFBP-3 molecule

Insulin-like growth factor binding protein-3 (IGFBP-3) binds to specific membrane proteins located on human breast cancer cells, which may be responsible for mediating the IGF-independent growth inhibitory effects of IGFBP-3. In this study, we evaluated IGFBP-3 binding sites on breast cancer cell membranes by competitive binding studies with IGFBP-1 through -6 and various forms of IGFBP-3, including synthetic IGFBP-3 fragments. Scatchard analysis revealed the existence of high-affinity sites for IGFBP-3 in estrogen receptor-negative Hs578T human breast cancer cells (dissociation constant (Kd) = 8.19 +/- 0.97 x 10(-9) M and 4.92 +/- 1.51 x 10(5) binding sites/cell) and 30-fold fewer receptors in estrogen receptor-positive MCF-7 cells (Kd = 8.49 +/- 0.78 x 10(-9) M and 1.72 +/- 0.31 x 10(4) binding sites/cell), using a one-site model. These data demonstrate binding characteristics of typical receptor-ligand interactions, strongly suggesting an IGFBP-3:IGFBP-3 receptor interaction. Among IGFBPs, only IGFBP-5 showed weak competition, indicating that IGFBP-3 binding to breast cancer cell surfaces is specific and cannot be attributed to nonspecific interaction with glycosaminoglycans. This was confirmed by showing that synthetic IGFBP-3 peptides containing IGFBP-3 glycosaminoglycan-binding domains competed only weakly for IGFBP-3 binding to the cell surface. Rat IGFBP-3 was 20-fold less potent in its ability to compete with human IGFBP-3(Echerichia coli), as well as 10- to 20-fold less potent for cell growth inhibition than human IGFBP-3, suggesting the existence of species specificity in the interaction between IGFBP-3 and the IGFBP-3 receptor. When various IGFBP-3 fragments were evaluated for affinity for the IGFBP-3 receptor, only those fragments that contain the midregion of the IGFBP-3 molecule were able to inhibit 125I-IGFBP-3(Escherichia coli) binding, indicating that the midregion of the IGFBP-3 molecule is responsible for binding to its receptor. These observations demonstrate that specific, high-affinity IGFBP-3 receptors are located on breast cancer cell membranes. These receptors have properties that support the notion that they may mediate the IGF-independent inhibitory actions of IGFBP-3 in breast cancer cells.

NO contribution to lipopolysaccharide-induced hepatic damage in galactosamine-sensitized mice

To investigate the role of nitric oxide (NO) in hepatitis-induced endotoxemia, we injected mice intraperitoneally with 250 mg/kg galactosamine (GalN) and 1 mg/kg lipopolysaccharide (LPS) separately and in combination. NO synthesis increased in a dose-dependent manner with LPS. NO generation at 5 hr after administration of LPS was greater than that at 24 hr. Enhancement of NO generation was demonstrated in mice administered GalN and LPS in combination. A nitrosyl-heme signal in 10,000 g supernatant of liver homogenate, due to cytochrome P450 (P450) combining with NO, NO-P450, was detected at more than ten hr and even more after administration of LPS by electron spin resonance (ESR) measurements at 77 degrees K. The strongest NO-P450 signal and most extreme elevation of aspartate oxoglutarate aminotransferase (AST), alanine oxoglutarate aminotransferase (ALT), and lactate dehydrogenase (LDH) in serum and of lysosomal enzyme activity in plasma were observed in the GalN + LPS group. Their potency was greater than in the 10 mg/kg LPS group, which was even greater than in the LPS 1 mg/kg group. The aniline hydroxylase activity was inversely proportional to NO-P450 signal intensity. It appears that NO might contribute to LPS-induced hepatic damage in GalN-sensitized mice through degeneration and inactivation of liver microsomal enzymes by binding P450 active sites.

Angiomyolipoma of the liver: case report and collective review of cases diagnosed from fine needle aspiration biopsy specimens

We experienced a rare case of primary angiomyolipoma (AML) of the liver, preoperatively diagnosed by fine needle aspiration biopsy (FNAB). Radiographic imaging revealed characteristic features of an angiomyolipoma. The diagnosis was confirmed by the presence of epithelioid smooth muscle cells, mature fat cells and blood vessels in the biopsy tissue. Our review of the literature showed this to be the eleventh case to be diagnosed in this way. Despite this preoperative diagnosis, the lesion was resected because of its pleomorphic histological features. Histologically, the epithelioid smooth muscle component included cells with a bizarre appearance and occasional hyperchromatic nuclei, and furthermore, occasional mitotic figures were observed. In own MEDLINE search of the literature we found 11 cases of AML of the liver for which the diagnoses were established by FNAB, and the same features were present in 5 cases for which surgical excision was contemplated.

Serum free insulin-like growth factor I (IGF-I), total IGF-I, and IGF-binding protein-3 concentrations in normal children and children with growth hormone deficiency

To evaluate the role of serum free or unbound insulin-like growth factor I (IGF-I) on bone growth, we measured serum free IGF-I levels in 354 healthy children and adults (193 males and 161 females, aged 0-40 yr) and in 21 prepubertal GH-deficient (GHD) children (complete GHD, n = 5; partial GHD, n = 16) using a recently developed immunoradiometric assay. We obtained the following results. 1) In the normal children, the serum free IGF-I levels were low in infancy (<1 yr of age; males, 0.71 +/- 0.26 microg/L, mean +/- SD; females, 1.05 +/- 0.49 microg/L), increased during puberty (males, 5.84 +/- 2.18 microg/L; females, 5.80 +/- 1.49 microg/L), and declined thereafter. 2) Free IGF-I in the serum occupied about 0.95-2.02% of the total IGF-I values, with the highest ratio occurring in infancy (males, 1.77 +/- 0.60%; females, 2.02 +/- 0.87%). 3) The SD scores of serum free IGF-I in the 21 GHD children ranged from -3.30 to 0.30, and the 5 complete GHD children had free IGF-I values more than -2 SD below those of age-matched normal subjects. 4) There was a significant correlation between the SD scores of free IGF-I and those of total IGF-I (r = 0.715; P < 0.0005) in the GHD children. 5) In the 16 partial GHD children receiving GH treatment, the serum free IGF-I levels were elevated to 209% of pretreatment levels after 1 month of GH treatment and remained high during GH therapy. The GH-induced increase in the serum free IGF-I levels was significantly higher than those of the total IGF-I and IGF binding protein-3 levels. 6) The percent increase in the serum free IGF-I level after 1 month of GH treatment showed a significant positive correlation with that of the GH-induced improvement in the percent increase in the height velocity during 1 yr of GH therapy (r = 0.526; P < 0.05). These results show that free IGF-I in the serum has an essential role in bone formation because the higher free IGF-I levels were observed when the growth rate accelerated. The measurement of serum free IGF-I may become a useful tool for both diagnosing GH deficiency and predicting growth responses to long term GH therapy.

Glibenclamide, an antagonist of ATP sensitive K+ channels, blocks free radical generation in the rat myocardium

The present study examined the effect of glibenclamide, an ATP-sensitive K+ (K(ATP)) channels antagonist, on the potassium chloride (KCl)-induced hydroxyl free radical (.OH) generation. Sodium salicylate in Ringer's solution (0.5 nmol/microl per min) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rat. The high concentration of KCl (70 mM) significantly increased the level of 2,3- and 2,5-DHBA by the action of depolarization by KCl. However, in the presence of glibenclamide (10 microM), KCl failed to increase the 2,3- and 2,5-DHBA formation. Moreover, when allopurinol (10 mg/kg), a xanthine oxidase inhibitor, was administered by i.v. injection, the elevation of DHBA was not observed. These results suggest that openings of cardiac K(ATP) channel by depolarization evokes .OH generation via xanthine oxidase reaction.

NO and cGMP facilitate adenosine production in rat hearts via activation of ecto-5'-nucleotidase

We examined whether nitric oxide (NO), a possible cardioprotective substance, can increase the production of interstitial adenosine in the ventricular myocardium. A flexibly mounted microdialysis technique was used to measure the concentration of interstitial adenosine and to assess the activity of ecto-5'-nucleotidase in in vivo rat hearts. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rats and perfused with Tyrode solution containing adenosine 5'-monophosphate (AMP) at a rate of 1.0 microl min-1. The concentration of adenosine in the effluent (dialysate) was measured by high-performance liquid chromatography. Dialysate adenosine obtained during perfusion with the AMP-containing solution through the probe originated from the hydrolysis of AMP by endogenous ecto-5'-nucleotidase, and the level of adenosine reflected the activity of ecto-5'-nucleotidase in the tissue. S-Nitroso-N-acetylpenicillamine (SNAP, 0.3-3 mM), an NO donor, increased the dialysate adenosine measured in the presence of AMP (100 microM) in a concentration-dependent manner. However, in the presence of an NO-oxidizing agent, 2-(4-carboxyphenyl-4,4,5, 5-tetramethylimidazoline)-1-oxyl 3-oxide (carboxy-PTIO, 1 mM), the effect of SNAP was abolished. Another NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409, 1 mM) also increased adenosine production. 8-Bromo-cGMP (0.1-3 mM), a membrane-permeable cGMP analogue and a potent activator of cGMP-dependent protein kinase, increased the level of AMP-primed dialysate adenosine in a concentration-dependent manner. These results suggest that NO facilitates the production of interstitial adenosine in rat hearts in situ, via cGMP-mediated activation of ecto-5'-nucleotidase.

Differentiated phenotype of smooth muscle cells depends on signaling pathways through insulin-like growth factors and phosphatidylinositol 3-kinase

Under conventional culture conditions, smooth muscle cells display their phenotypic modulation from a differentiated to a dedifferentiated state. Here, we established a primary culture system of smooth muscle cells maintaining a differentiated phenotype, as characterized by expression of smooth muscle-specific marker genes such as h-caldesmon and calponin, cell morphology, and ligand-induced contractility. Laminin retarded the progression of dedifferentiation of smooth muscle cells. Insulin-like growth factors (IGF-I and IGF-II) and insulin markedly prolonged the differentiated phenotype, with IGF-I being the more potent. In contrast, serum, epidermal growth factor, transforming growth factors, and platelet-derived growth factors potently induced dedifferentiation compared with angiotensin II, arginine-vasopressin, and basic fibroblast growth factor. Using the present culture system, we investigated signaling pathways regulating a phenotype of smooth muscle cells. In cultured cells, IGF-I specifically activated phosphatidylinositol 3-kinase (PI3-kinase) and its downstream target, protein kinase B, but not mitogen-activated protein kinases. Specific inhibitors of PI3-kinase (wortmannin and LY294002) induced dedifferentiation of smooth muscle cells even when they were cultured on laminin under IGF-I-stimulated conditions. The sole effect of laminin to retard the dedifferentiation was completely blocked by anti-IGF-I antibody, and laminin promoted the endogenous expression of IGF-I in cultured cells. The reduced promoter activity of the caldesmon gene induced by platelet-derived growth factor BB was overcome by the forced expression of the constitutive active form of PI3-kinase p110alpha catalytic subunit. These findings suggest that an IGF-I signaling pathway through PI3-kinase plays a critical role in maintaining a differentiated phenotype of smooth muscle cells.

Effects of lysophosphatidylcholine on the production of interstitial adenosine via protein kinase C-mediated activation of ecto-5'-nucleotidase

1. Adenosine plays a crucial role in the evolution of ischemic preconditioning. With the use of microdialysis techniques in in situ rat hearts, we assessed the activity of ecto-5'-nucleotidase (a key enzyme responsible for adenosine production), and examined the effects of lysophosphatidylcholine (LPC) on the production of interstitial adenosine. 2. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rat hearts and perfused with Tyrode solution containing adenosine 5'-monophosphate (AMP, 100 microM). With this system, the dialysate adenosine originates from the dephosphorylation of AMP, catalyzed by endogenous ecto-5'-nucleotidase. The level of dialysate adenosine is a measure of the ecto-5'-nucleotidase activity in vivo. 3. LPC at concentrations of 25 and 50 microM significantly increased the level of dialysate adenosine to 122.7+/-4.3% (n=4, P<0.05) and 158.6+/-7.2% (n=5, P<0.05) of the control, respectively. Chelerythrine (200 microM), a protein kinase C (PKC) inhibitor, completely abolished the increase of dialysate adenosine afforded by LPC (50 microM) (n=5). 4. These data provide the first evidence that LPC does increase the concentration of interstitial adenosine in rat hearts in situ, through the PKC-mediated activation of endogenous ecto-5'-nucleotidase.

Variation of monoamines and their metabolite contents in the cerebrospinal fluid of conscious rats

To study the circadian rhythm of the monoamine and metabolite contents, cerebrospinal fluid was taken from the cisterna magna through a polyethylene catheter tube every 4 hr in the conscious rat. Norepinephrine and 3-methoxy-4-hydroxy-phenylglycol were found to describe a rhythm with the maximal content occurring during the dark phase and the minimal content occurring during the light phase. Dopamine levels increased significantly during the light phase compared with the dark phase. These results, given that cerebrospinal fluid can be taken chronically from conscious rats, indicate that our present method may be suitable for estimating changes in brain monoamine and metabolite contents.

A novel homeobox gene, dharma, can induce the organizer in a non-cell-autonomous manner

The formation of Spemann organizer is one of the most important steps in dorsoventral axis determination in vertebrate development. However, whether the organizer forms autonomously or is induced non-cell-autonomously is controversial. In this report we have isolated a novel zebrafish homeobox gene, dharma, capable of inducing the organizer ectopically. The expression of dharma was first detected in several blastomeres at one side of the margin soon after the mid-blastula transition and continued in the dorsal side of the yolk syncytial layer (YSL) under the embryonic shield, the zebrafish organizer, until the onset of gastrulation. Furthermore, dharma expressed in the YSL induced the organizer in a non-cell-autonomous manner. These results provided the first identification of a zygotic gene to be implicated in the formation of an organizer-inducing center.

[Clinical staging of prostate cancer]

Clinical staging of prostate cancer was reviewed on the basis of TNM classification edited by UICC in 1997. In this revision, (1) T1c was newly categorized among T1 for cases of high PSA level without any abnormal sign of DRE, (2) T2 was subdivided into T2a and T2b in accordance with unilateral or bilateral nodule in the prostate, respectively, (3) T3 was also subdivided into T3a with capsular invasion and T3b with seminal vesicle invasion. It is hoped that present classification will become useful tools for the detection of the tumor burden cancer patients.

Gab1 acts as an adapter molecule linking the cytokine receptor gp130 to ERK mitogen-activated protein kinase

Gab1 has structural similarities with Drosophila DOS (daughter of sevenless), which is a substrate of the protein tyrosine phosphatase Corkscrew. Both Gab1 and DOS have a pleckstrin homology domain and tyrosine residues, potential binding sites for various SH2 domain-containing adapter molecules when they are phosphorylated. We found that Gab1 was tyrosine phosphorylated in response to various cytokines, such as interleukin-6 (IL-6), IL-3, alpha interferon (IFN-alpha), and IFN-gamma. Upon the stimulation of IL-6 or IL-3, Gab1 was found to form a complex with phosphatidylinositol (PI)-3 kinase and SHP-2, a homolog of Corkscrew. Mutational analysis of gp130, the common subunit of IL-6 family cytokine receptors, revealed that neither tyrosine residues of gp130 nor its carboxy terminus was required for tyrosine phosphorylation of Gab1. Expression of Gab1 enhanced gp130-dependent mitogen-activated protein (MAP) kinase ERK2 activation. A mutation of tyrosine 759, the SHP-2 binding site of gp130, abrogated the interactions of Gab1 with SHP-2 and PI-3 kinase as well as ERK2 activation. Furthermore, ERK2 activation was inhibited by a dominant negative p85 PI-3 kinase, wortmannin, or a dominant negative Ras. These observations suggest that Gab1 acts as an adapter molecule in transmitting signals to ERK MAP kinase for the cytokine receptor gp130 and that SHP-2, PI-3 kinase, and Ras are involved in Gab1-mediated ERK activation.

Induction of DNA fragmentation by nicotine in human myelogenous leukemic cell lines

The effect of nicotine, a component of tobacco, on the cytokine production and cell growth of various cultured cells was investigated. Nicotine did not stimulate, but rather inhibited the tumor necrosis factor production by human peripheral blood mononuclear cells at higher doses. Cytotoxic concentrations of nicotine did not induce the monocytic and granulocytic differentiation of human myelogenous leukemic cell lines (HL-60, ML-1). Nicotine induced internucleosomal DNA cleavage in these leukemic cell lines but not in human peripheral blood lymphocytes and polymorphonuclear cells. The fragmentation-inducing activity of nicotine was not prevented by simultaneous addition of ascorbic acid. Flow cytometry showed a slight increase in the number of G2 + M phase cells, before the appearance of the apoptosis peak. Nicotine transiently increased the intracellular calcium concentration to higher levels in leukemic cells than in normal leukocytes. These data suggest that the induction of DNA fragmentation requires elevation of intracellular calcium concentration above a certain threshold level.

Uncoupling of incorporation of ascorbic acid and apoptosis induction

Exposure of human promyelocytic leukemic HL-60 cells to millimolar concentration of sodium ascorbate induced apoptotic cell death. The extent of apoptosis induction was a positive function of temperature at the time of exposure. The incorporation of [1-14C] ascorbic acid into the cytosolic fraction of HL-60 cells was also temperature-dependent, and competitively inhibited by active analogs (L-ascorbic acid, sodium L-ascorbate, D-isoascorbic acid, sodium 6-beta-O-galactosyl-L-ascorbate, sodium 5,6-benzylidene-L-ascorbate), but not by inactive analogs (L-ascorbic acid-2-phosphate magnesium, L-ascorbic acid 2-sulfate). Calcium depletion, which had considerably reduced the apoptosis-inducing activity of sodium ascorbate, did not affect the intracellular incorporation of [14C] ascorbic acid. These data suggests that cell death might not be simply induced by the intracellular incorporation of ascorbate, but rather initiated by the rapid elevation of intracellular Ca2+ concentration, possibly mediated by an as yet unidentified temperature-sensitive mechanism.

Calcium mobilization during nicotine-induced cell death in human glioma and glioblastoma cell lines

Nicotine dose-dependently induced cytotoxicity in human glioma (KG-1-C) and glioblastoma (GBS-1, T98G) cell lines, but could not induce internucleosomal DNA cleavage, in contrast to apoptosing human myelogenous leukemic cell lines. Human glioma/glioblastoma cell lines thus might have a chromatin structure resistant to endonuclease digestion. Nicotine induced a rapid increase in the intracellular calcium concentration. Confocal experiments with Fluo-3 fluorescence revealed that nicotine elevated the free Ca2+ concentration in both nuclear and cytoplasmic regions of the cells, and the elevation of Ca2+ in the nuclear region was more pronounced than that of the cytoplasmic region. The present study suggests that nuclear accumulation of Ca2+ is an important initial step for cell death induction by nicotine.

Malignant fibrous histiocytoma originating from the chest wall: report of a case and collective review of cases

Malignant fibrous histiocytomas occur principally as a mass of the extremities, abdominal cavity, or retroperitoneum in adults. However, they only rarely occur in the chest wall. A rare case of primary malignant fibrous histiocytoma originating from the chest wall is herein presented. The 36 previously reported cases are also reviewed. Of the 32 patients who underwent a resection as the initial treatment, 10 (31.3%) had a local recurrence. Of the 37 patients with this disease, 9 (25.0%) had subsequent metastases. The majority of the deaths (36.1%) from this disease occurred within the first 12 months. The patients who undergo surgical and adjuvant therapy must therefore be monitored carefully by frequent examinations.

[Prostatectomy for prostate cancers]

Radical prostatectomy may afford cure in men in whom the malignancy is completely extirpable. Historical experiences as well as ours agreed that long term survival after radical prostatectomy was excellent if the disease was confined to the organ. Cure may also be expected in some selected patients with minimal extra-organ invasion. Furthermore, preoperative hormonal therapy may improve the cure rate in these invasive diseases. However, if cure means affording the patient the best chance of dying of some causes other than cancer, some of those extirpable diseases may be cured without surgery. This idea was supported by epidemiologic data on the natural history of the disease, and retrospective observations of conservatively treated patients. Challenging issues toward the 21st century are to expand the range of surgically curative diseases, and to identify diseases extirpable but predestined never to kill the host during the natural course of his life.

Insulin and IGF binding by IGFBP-3 fragments derived from proteolysis, baculovirus expression and normal human urine

Recombinant human IGFBP-3 was proteolysed with different concentrations of plasmin for various periods of time. The major IGFBP-3 fragment resulting from this digestion migrated at ca. 15 kDa in nonreducing SDS-PAGE. Following the identification of this fragment as an N-terminal IGFBP-3 fragment, by use of N-terminus-specific monoclonal antibody and amino acid sequence analysis, we constructed and expressed a similar fragment in a baculovirus expression system. The fragments resulting from plasmin digestion, as well as the baculovirus-expressed recombinant human IGFBP-3(1-97), retain weak IGF binding and show specific insulin binding on cross-linking and western ligand blot. RhIGFBP-3(1-97) can inhibit insulin receptor autophosphorylation in insulin receptor-overexpressing NIH 3T3 cells. Insulin and IGF binding to IGFBP-3 fragments could be further demonstrated in normal urine. These data indicate the physiological significance of IGFBP-3 fragments derived from proteolysis in vivo.

Autoregulation of the Stat3 gene through cooperation with a cAMP-responsive element-binding protein

STAT3 (signal transducer and activator of transcription 3) is a key transcription factor mediating the signals for a variety of cytokines, including interleukin-6 (IL-6). The Stat3 gene itself is activated by IL-6 signals. We show that the region of the signal-transducing subunit, gp130, essential for STAT3 activation, is also required for activation of the Stat3 gene. To elucidate the mechanisms activating the Stat3 gene, we identified an IL-6 response element (IL-6RE) in the Stat3 gene promoter containing both a low affinity STAT3-binding element and a cAMP-responsive element (CRE). Electrophoretic mobility shift assays showed that IL-6 induced a slowly migrating complex on the IL-6RE containing a STAT3 homodimer and an unidentified CRE-binding protein. With the combination of transient transfection assays using mutant Stat3 promoter-reporter constructs and electrophoretic mobility shift assays, we found that the formation of a slowly migrating complex was required for full activation of the Stat3 gene. Thus, STAT3 activates the Stat3 gene in cooperation with an unidentified CRE-binding protein. This regulatory mechanism is similar to that of the junB gene, which is activated by IL-6 through the junB IL-6RE, which contains a low affinity STAT3-binding site and a CRE-like site.

[Assay for oxidative stress injury by detection of luminol-enhanced chemiluminescence in a freshly obtained blood sample: a study to follow the time course of oxidative injury]

To evaluate occurrence of oxidative stress in circulating blood, we developed standard methods to assess (1) granulocytes status as a source of reactive oxygen species (ROS) and (2) lipid peroxidation (LPO). A simplified and highly sensitive assay was developed by utilizing the chemiluminescence (CL) from luminol oxidized by ROS. 1. The CL, from 300 microliters medium containing 1% blood, 10 micrograms/ml luminol and 0.025 microgram/ml phorbol myristate acetate, well reflected the primed granulocyte status induced by in vitro contact with lipopolysaccharide (LPS). This CL was weakened slightly by superoxide dismutase and catalase, but markedly decreased by sodium azide. 2. We determined the optimal conditions for the t-butyl hydroperoxide (t-BuOOH)-stimulated CL method to evaluate plasma LPO in experiments on rat plasma added with phosphatidylethanolamine hydroperoxide (PEOOH). The CL from 300 microliters medium containing 6.67% plasma. 10 micrograms/ml luminol and 5 mumol/ml t-BuOOH was proportional to the added PEOOH amount. The integrated CL of the plasma with 0-60 nmol of PEOOH gave values of 8.280-14.213 x 10(6) counts/60 min/tube. 3. Only 100 microliters of freshly drawn blood was enough for the two CL methods to detect the generation of ROS and the occurrence of LPO. These CL methods enabled the determination of the time course of oxidative stress occurrence in circulating blood of rats treated with 5 mg/kg LPS, i.p.

Conformational behaviour of C(alpha,alpha)-diphenylglycine: folded vs. extended structures in DphiG-containing tripeptides

The crystal structures of three fully protected tripeptides containing the Dphi g residue (C[alpha,alpha]-diphenylglycine) in the central position are reported, namely Z-Gly-Dphi g-Gly-OMe (a), Z-Gly-Dphi g-Aib-OMe (b) and Z-Aib-Dphi g-Aib-OMe (c). The molecular conformations are quite unusual because the Dphi g residue adopts a folded conformation in the 3(10)-helical region when the following residue adopts a folded conformation of opposite handedness (peptides b and c). In contrast, the Dphi g residue adopts the more frequently observed fully extended conformation when the following residue adopts a semi-extended conformation (peptide a). These findings are in agreement with the theoretical calculations on Ac-Dphi g-Aib-NHCH3 and Ac-Aib-Dphi g-NHCH3 also reported in this work.

Effect of .OH scavenging action by non-SH-containing angiotensin converting enzyme inhibitor imidaprilat using microdialysis

We examined the effect of non-SH-containing angiotensin converting enzyme (ACE) inhibitor imidaprilat on hydroxyl radical (.OH) generation using microdialysis. Salicylic acid in Ringer's solution containing sodium salicylate (0.5 n mol microL-1 min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. We compared the ability of two non-SH-containing ACE inhibitors (imidaprilat and enalaprilat) with an -SH-containing ACE inhibitor (captopril) to scavenge the .OH. When iron (II) was administered to animals pretreated with these three ACE inhibitors, a decrease in 2,3-DHBA of all three compounds was observed, as compared with the iron (II) only-treated group. All three ACE inhibitors were able to scavenge .OH generated by the action of iron (II). However, imidaprilat is a free radical scavenger more potent than enalaprilat. These results suggested that ACE inhibitors are probably not only related to the presence of the SH radical.

Adenosine deaminase activity in rat intestine: assay with a microdialysis technique

Using microdialysis, we measured adenosine deaminase activity in rat intestine by detecting inosine, a breakdown product of adenosine. The dialysis probe consisted of a 3 x 0.22 mm dialysis fiber with a 50,000 mol wt cut off. When the probe was perfused at 1 microl/min in vitro, the average relative recovery rate of inosine was 22.1+/-0.9%). The dialysis probe was implanted in the intestinal mucosa and perfused with Tyrode solution containing adenosine at 1 microl/min. The dialysate samples were analyzed for inosine by high-performance liquid chromatography with ultraviolet (HPLC-UV) detection at 260 nm. When adenosine (100-1000 microM) was perfused, the level of inosine increased dose-dependently and was saturatable at about 1 mM adenosine. The ED50 of adenosine was 192.6 microM, with a maximum attainable inosine concentration of 59.7 microM. In the presence of aminoguanidine, a adenosine deaminase inhibitor (10 mM or 10 n mol/microl/min), the elevation of inosine was not observed. The dialysis technique makes it possible to measure adenosine deaminase activity in intestinal mucosa.

Overexpression of neurogenin induces ectopic expression of HuC in zebrafish

Several basic helix-loop-helix (bHLH) transcription factors are known to be involved in vertebrate neurogenesis. To investigate their roles in zebrafish neurogenesis, we isolated cDNAs for homologues of neurogenin and Math(-1)/atonal. The transcription of neurogenin was first detectable in zebrafish nervous system at late gastrulation stage. The expression of zebrafish neurogenin precedes and overlaps that of HuC, one of the earliest neuronal precursor markers. Injection of neurogenin mRNA into early stage zebrafish embryos induced ectopic expression of HuC. These results suggest that neurogenin may participate in the generation of HuC-expressing cells, implying its role in neuronal determination in zebrafish.

Inhibition of insulin receptor activation by insulin-like growth factor binding proteins

The insulin-like growth factors (IGFs) are transported by a family of high-affinity binding proteins (IGFBPs) that protect IGFs from degradation, limit their binding to IGF receptors, and modulate IGF actions. The six classical IGFBPs have been believed to have no affinity for insulin. We now demonstrate that IGFBP-7/mac25, a newly identified member of the IGFBP superfamily that binds IGFs specifically with low affinity is a high-affinity insulin binding protein. IGFBP-7 blocks insulin binding to the insulin receptor and thereby inhibiting the earliest steps in insulin action, such as autophosphorylation of the insulin receptor beta subunit and phosphorylation of IRS-1, indicating that IGFBP-7 is a functional insulin-binding protein. The affinity of other IGFBPs for insulin can be enhanced by modifications that disrupt disulfide bonds or remove the conserved COOH terminus. Like IGFBP-7, an NH2-terminal fragment of IGFBP-3 (IGFBP-3((1-87))), also binds insulin with high affinity and blocks insulin action. IGFBPs with enhanced affinity for insulin might contribute to the insulin resistance of pregnancy, type II diabetes mellitus, and other pathological conditions.

The effect of glibenclamide on the production of interstitial adenosine by inhibiting ecto-5'-nucleotidase in rat hearts

1. Adenosine exerts cardioprotective effects on the ischaemic myocardium. The production of adenosine in the ischaemic myocardium is attributed primarily to the enzymatic dephosphorylation of adenosine 5'-monophosphate (AMP) by 5'-nucleotidase. We determined the activity of 5'-nucleotidase in rat hearts. The objective of the study was to determine the effects of ATP-sensitive K+ (K[ATP]) channel antagonists (glibenclamide and 5-hydroxydecanoate) on the production of adenosine, by use of a flexibly mounted microdialysis technique. 2. Rats were anaesthetized and the microdialysis probe was implanted in the left ventricular myocardium, followed by perfusion with Tyrode solution. The baseline level of dialysate adenosine was 0.51 +/- 0.09 microM (n = 16). Introduction of AMP (100 microM) through the probe increased the dialysate adenosine markedly to 9.79 +/- 0.43 microM (n = 12, P < 0.001 vs baseline), and this increase was inhibited by the ecto-5'-nucleotidase inhibitor, alpha,beta-methyleneadenosine 5'-diphosphate (100 microM), to 0.76 +/- 0.12 microM (n = 8). Thus, the dialysate adenosine noted during the perfusion of AMP originated from dephosphorylation of AMP by ecto-5'-nucleotidase, and the dialysate level of adenosine attained reflects the ecto-5'-nucleotidase activity in the tissue in situ. 3. Glibenclamide (0.1-100 microM) decreased the adenosine concentration measured during the perfusion of AMP (100 microM) in a concentration-dependent manner (IC50 = 10.5 microM). In contrast, 5-hydroxydecanoate (10-100 microM) did not affect the concentrations of dialysate adenosine, measured in the presence of AMP (100 microM). These results suggest that glibenclamide inhibits the activity of endogenous ecto-5'-nucleotidase and decreases the concentration of adenosine in the interstitial space of rat ventricular muscles in situ.

Induction of apoptosis in megakaryocytic leukemia cell lines by MX2, a morpholino anthracycline

Leukemia with megakaryocytic involvement has a poor prognosis. MX2 is a new morpholino anthracycline that is effective against various leukemic cell lines. This study examined the antitumor activity of MX2 against human megakaryocytic cell lines, including CMK, CMK11-5, MEG-01, and UT-7, and investigated the role of apoptosis in the cytotoxicity of this drug. To quantify the extent of apoptosis induced by MX2, we used the in situ terminal deoxynucleotide transferase assay and the histone-associated DNA fragmentation assay. The cytotoxic effect of MX2 on CMK cells was reduced by various inhibitors of apoptosis. To our knowledge, this is the first report showing that apoptosis is involved in the killing of megakaryocytic cell lines by an antileukemic agent. We suggest that MX2 may be useful for the treatment of megakaryocytic leukemia.

Stimulation of alpha 1-adrenoceptors and protein kinase C-mediated activation of ecto-5'-nucleotidase in rat hearts in vivo

1. To determine whether protein kinase C (PKC)-mediated activation of ecto-5'-nucleotidase would increase interstitial adenosine concentrations in the rat heart in vivo, we made use of the microdialysis technique and a flexibly mounted probe, which was implanted in the left ventricular myocardium and perfused with Tyrode solution. 2. The baseline level of dialysate adenosine was 0.51 +/- 0.09 microM (n = 16). Perfusion of adenosine 5'-monophosphate (AMP, 100 microM) through the probe increased the dialysate adenosine concentration markedly to 9.25 +/- 0.46 microM (n = 15). alpha, beta-Methyleneadenosine 5'-diphosphate (AOPCP, 100 microM), an inhibitor of ecto-5'-nucleotidase, abolished the AMP-induced increase in dialysate adenosine, but did not affect the baseline level of adenosine. These observations suggest that the dialysate adenosine obtained during the perfusion with AMP, but not the baseline levels of adenosine, originated from the dephosphorylation of AMP by ecto-5'-nucleotidase. Thus, the level of adenosine measured during AMP perfusion gives an index of the activity of ecto-5'-nucleotidase in the tissue. 3. Noradrenaline (10 microM) increased the adenosine concentration measured in the presence of 100 microM AMP (i.e. the activity of ecto-5'-nucleotidase) by 38.7 +/- 9.6% (n = 5, P < 0.05), an increase which was inhibited by an antagonist of the alpha 1-adrenoceptor (prazosin, 50 microM) or of PKC (chelerythrine, 10 microM). Further application of either the alpha 1-adrenoceptor agonist methoxamine (100 microM) or the diacylglycerol analogue 1,2-dioctanoyl-sn-glycerol (DOG, 100 microM) also increased the adenosine concentration by 35.1 +/- 10.0% (n = 6, P < 0.05) or 40.6 +/- 8.3% (n = 5, P < 0.05), respectively. 4. The presence of okadaic acid (50 microM), an inhibitor of protein phosphatase, enhanced the noradrenaline-induced increase in adenosine concentration by 112.4 +/- 35.9% (n = 4, P < 0.05), to a level significantly (P < 0.05) greater than the increase caused by noradrenaline alone (38.7 +/- 9.6%). 5. These data provide the first evidence that alpha 1-adrenoceptor stimulation and the subsequent activation of PKC can increase adenosine concentrations in interstitial spaces of ventricular muscle in vivo, through activation of endogenous ecto-5'-nucleotidase.

Evidence of hydroxyl free radical generation by calcium overload in rat myocardium

Although calcium (Ca2+) is important in cardiac dysfunction and has also been reported as a source of oxidative toxicity, the connection between Ca2+ overload and oxygen free radicals in the myocardium is not clear. We have investigated whether Ca2+ overload generates hydroxyl free radicals in rat ventricle. HPLC with electrochemical detection was used to measure the levels of 2,3- and 2,5-dihydroxybenzoic acid (DHBA) formed when the hydroxyl free radical reacts with salicylate. Ringer's solution containing salicylic acid (0.5 nmol microL-1 min-1) was infused through a microdialysis probe in the region of the left anterior descending coronary artery of the rat ventricle. A positive linear correlation was obtained between Ca2+ and hydroxyl free radical formation trapped as 2,3-DHBA (r2 = 0.976) and 2,5-DHBA (r2 = 0.982) in the myocardial dialysate. The administration of ouabain (1 mg kg-1, i.v.), a Ca2+ elevator, into the femoral vein significantly increased the level of 2,3- and 2,5-DHBA. These results indicate that Ca2+ overload generates hydroxyl free radicals in rat heart.

[Detection and characterization of free radicals, radical scavenging activity, and lipid peroxides in cerebral ischemia-reperfusion injury by electron spin resonance and chemiluminescence high-performance liquid chromatography]

During the ischemia-reperfusion period, the hypoxanthine-xanthine oxidase system simultaneously generates superoxide (O2-). O2- has an extremely short half-life, as it rapidly undergoes Fenton-type reactions in the presence of iron and yields highly cytotoxic hydroxyl radicals (.OH). Oxygen-derived free radicals are induced as a contributing cause of cellular injury in several neurological disorders, including cerebral infarction and aging. Cerebral injury by ischemia-reperfusion following middle cerebral artery occlusion could be useful experimental model for studying cerebral injury induced by free radicals. Thiobarbituric acid reactants generally indicate lipid peroxidation associated with cellular damage caused by free radicals. Phosphatidylethanolamine hydroperoxide (PEOOH) is the primary peroxidative product of phosphatidylethanolamine, which is the most important functional lipid in the membrane. Plasma PEOOH levels appear to be a reliable indicator of cerebral damage caused by ischemia-reperfusion and other oxidative stress. Recently, an electron spin resonance (ESR) spectrometer was used in the detection of free radicals, in vivo and in vitro using 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) as the radical-trapping reagent. Moreover, there are reports the electron spin resonance-computed tomography (ESR-CT) images of the cephalic region of rats for locating regions of pathological change are related to free radicals in the brain.

Polyangiitis overlap syndrome

A 33-year-old man was admitted to our hospital because of intermittent claudication and finger tip ulceration with a skin rash on the upper and lower extremities. He later developed a massive melena. Angiography revealed arterial occlusion in the hand and foot, skin biopsy showed vasculitis with eosinophilic infiltration, and biopsy of the colon showed mucosal vasculitis with thrombosis. A diagnosis of polyangiitis overlap syndrome was made, and all these symptoms improved after corticosteroid therapy.

Structural features of the gene encoding human muscle type carnitine palmitoyltransferase I

We isolated a human muscle type of carnitine palmitoyltransferase I (CPTI-M) genomic clone and determined its entire nucleotide sequence. By comparison of the nucleotide sequence of the genomic clone with that of cDNA, we determined the intron/exon junctions. For detection of the exon(s) in the 5'-region of the CPTI-M gene, we isolated cDNA clones corresponding to the 5'-region of its transcript by 5'-rapid amplification of cDNA ends (5'-RACE method). Results showed two alternative exons, 1A and 1B, that do not encode amino acids in the 5'-region of the human CPTI-M gene. The gene encoding human CPTI-M was found to consist of two 5'-non-coding exons, 18 coding exons and one 3'-non-coding exon spanning approximately 10 kbp. Furthermore, on analysis of the 5'-flanking region, a putative gene encoding a 'choline kinase homologue' was found to be located only about 300 bp upstream from exon 1A of the human CPTI-M gene. Comparison of the gene structure of human CPTI-M with the reported partial gene structure of human liver type CPTI (CPTI-L) showed that the intron insertion sites were completely conserved in these two genes.

Coordinate expression of alpha-tropomyosin and caldesmon isoforms in association with phenotypic modulation of smooth muscle cells

Isoform diversity of tropomyosin is generated from the limited genes by a combination of differential transcription and alternative splicing. In the case of the alpha-tropomyosin (alpha-TM) gene, exon 2a rather than exon 2b is specifically spliced in alpha-TM-SM mRNA, which is one of the major tropomyosin isoforms in smooth muscle cells. Here we demonstrate that expressions of alpha-tropomyosin and caldesmon isoforms are coordinately regulated in association with phenotypic modulation of smooth muscle cells. Molecular cloning and Western and Northern blottings have revealed that in addition to the down-regulation of beta-TM-SM, alpha-TM-SM converted to alpha-TM-F1 and alpha-TM-F2 by a selectional change from exon 2a to exon 2b during dedifferentiation of smooth muscle cells in culture. Simultaneously, a change of caldesmon isoforms from high Mr type to low Mr type was also observed by alternative selection between exons 3b and 4 in the caldesmon gene during this process. In contrast, cultured smooth muscle cells maintaining a differentiated phenotype continued to express alpha-TM-SM, beta-TM-SM, and high Mr caldesmon. In situ hybridization revealed specific coexpression of alpha-TM-SM and high Mr caldesmon in smooth muscle in developing embryos. These results suggest a common splicing mechanism for phenotype-dependent expression of tropomyosin and caldesmon isoforms in both visceral and vascular smooth muscle cells.

Protective effect of diltiazem on myocardial ischemic injury associated with .OH generation

We examined the protective effect of diltiazem, a calcium antagonist, on myocardial ischemic injury associated with generation of hydroxyl free radicals (.OH). Salicylic acid in Ringer's solution (0.5 nmol.microliter-1.min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium. Cardiac dialysate was assayed for 2,3-DHBA by a high-performance liquid chromatographic-electrochemical (HPLC-EC) procedure. The heart was subjected to myocardial ischemia for 15 min by occlusion of left anterior descending artery (LAD). The presence of .OH was indicated in the ischemic reperfused rat heart. However, when heart was reperfused, the elevation of 2,3-DHBA by 15-min ischemia was not observed in the ischemic zone following systemic administration of diltiazem (100 micrograms.min-1.kg-1), a calcium antagonist. When corresponding experiments were performed with allopurinol (10 mg.kg-1) administration of i.v. injection, the elevation of 2,3-DHBA was not observed. These results suggest that diltiazem may suppress the .OH generation from xanthine-xanthine oxidase system by ischemia-reperfusion.

Cardiac microdialysis of salicylic acid .OH generation on nonenzymatic oxidation by norepinephrine in rat heart

The effect of pargyline, a monoamine oxidase inhibitor, on the generation of hydroxyl free radicals (.OH) was investigated using cardiac microdialysis. Salicylic acid in Ringer's solution (0.5 nmol x microL(-1) x min(-1)) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. When pargyline (100 nmol x microL(-1) x min(-1)) was infused in rat heart, the level of norepinephrine (NE) gradually increased in a time-dependent manner and an increase of DHBA was also observed. When NE was administered to the pargyline pretreated animals, a marked elevation in the levels of 2,3- and 2,5-DHBA formation was obtained, as compared to the group treated with NE only, showing a positive linear correlation between NE and .OH formation trapped as 2,3-DHBA (R2 = 0.981) or 2,5-DHBA (R2 = 0.984) in the dialysate. NE clearly produced an increase in .OH formation. These results indicate that accumulation of NE in the extracellular fluid elicited by pargyline can be auto-oxidized, which in turn, leads (possibly by an indirect mechanism) to the formation of cytotoxic .OH free radicals.

Aplastic anemia complicating Sjögren's syndrome

A 47-year-old woman was referred to our hospital because of severe anemia and polyclonal gammopathy. She developed sicca syndrome after admission. Laboratory data revealed pancytopenia (white blood cells, 2,800/microliter; hemoglobin, 6.4 g/dl; platelets, 6.1 x 10(4)/microliter) and hyper gamma globulinemia (5.2 g/dl), and bone marrow was hypoplastic. Histology of the salivary gland showed infiltration of lymphocytes. We report a good response to immunosuppressive therapy in a rare case of aplastic anemia complicating Sjögren's syndrome.

Neuronal and muscular inclusions in rats with hindlimb dysfunction after treating with difluorobenzhydrylpiperadine

Rats showing an ataxic gait induced by 20 wk of treatment with 0, 30, or 60 mg/kg of difluorobenzhydrylpiperadine (DFBP), a detriazinyl metabolic of almitrine, were examined by light microscopy and transmission electron microscopy. Vacuolar degeneration associated with lamellar inclusions was observed in musculus soleus and m. interossei of the hindlimbs in DFBP-treated rats. The inclusions were also produced within sensory neurons, satellite and Schwann cells, and vascular endothelial cells of thoracic and lumbar dorsal root ganglia as well as muscle spindles of affected muscles. Membrane-bound vacuoles containing electron-dense granules were seen in the peripheral nerves. This study demonstrated neuronal and muscular toxicity of DFBP in rats.

Tyrosine phosphorylation and p72syk activation by an anti-glycoprotein Ib monoclonal antibody

NNKY5-5, an IgG monoclonal antibody directed against the von Willebrand factor-binding domain of glycoprotein (GP) Ib alpha, induced weak but irreversible aggregation (or association) of platelets in citrate-anticoagulated platelet-rich plasma. This phenomenon was defined as small aggregate formation (SAF). Platelets in hirudin-anticoagulated plasma or washed platelets showed little response to NNKY5-5 alone, but the antibody potentiated aggregation induced by low concentrations of adenosine diphosphate or platelet-activating factor. NNKY5-5 did not induce granule release or intracellular Ca2+ mobilization. However, NNKY5-5 caused tyrosine phosphorylation of a 64-kD protein and activation of a tyrosine kinase, p72syk. An anti-Fc gamma II receptor antibody had no effect on SAF, suggesting that NNKY5-5 activated platelets by interacting with glycoprotein Ib. Fab' fragments of NNKY5-5 did not induce SAF, but potentiated aggregation induced by other agonists. The Fab' fragment of NNKY5-5 induced the activation of p72syk, suggesting that such activation was independent of the Fc gamma II receptor. Cross-linking of the receptor-bound Fab' fragment of NNKY5-5 with a secondary antibody induced SAF. GRGDS peptide, chelation of extracellular Ca2+, and an anti-GPIIb/IIIa antibody inhibited NNKY5-5-induced SAF, but had no effect on 64-kD protein tyrosine phosphorylation or p72syk activations. Various inhibitors, including aspirin and protein kinase C, had no effect on SAF, protein tyrosine phosphorylation, or p72syk activation. In contrast, tyrphostin 47, a potent tyrosine kinase inhibitor, inhibited NNKY5-5-induced SAF as well as tyrosine phosphorylation and p72syk activation. Our findings suggest that binding of NNKY5-5 to GPIb potentiates platelet aggregation by facilitating the interaction between fibrinogen and GPIIb/IIIa through a mechanism associated with p72syk activation and tyrosine phosphorylation of a 64-kD protein.

An alternative pathway for STAT activation that is mediated by the direct interaction between JAK and STAT

JAK is believed to be an essential tyrosine kinase that mediates signals from the cytokine receptor to its downstream events. JAK associates with the cytoplasmic domain of the type I cytokine receptor superfamily and upon the ligand stimulation it can be activated, resulting in the receptor phosphorylation. In signaling from gp130, a common signal transducer for the IL-6 family cytokines, STAT3, a transcription factor that contains an SH2 domain, is recruited by phosphotyrosines on gp130 and is subsequently phosphorylated by gp130-associated JAKs. In this study, we attempted to find a new target for JAK that is directly activated by JAK, independent of gp130 tyrosine phosphorylation, by using a yeast two-hybrid system. In the process we found that the JH2 domain of JAK1, JAK2 or JAK3 could specifically associate with the carboxy-terminal portion of STAT5, but not with STAT3 or STAT1. The interaction was confirmed using both a transient expression system in a cell line and a GST-fusion protein binding assay. Furthermore, we showed that the activation of STAT5 via gp130 did not need any phosphotyrosines on gp130 while that of STAT3 strictly depended on phosphotyrosines on gp130. Mutations of STAT5 that eliminated the interaction with JAK1 reduced the activation of STAT5 upon the gp130 stimulation, although such mutants could be still activated through erythropoietin receptor. These results indicate that STATs are activated through cytokine receptors by two distinct mechanisms, one dependent on receptor tyrosine phosphorylation and the other mediated by the JAK-STAT direct interaction.

Alterations in acetylcholine, NMDA, benzodiazepine receptors and protein kinase C in the brain of the senescence-accelerated mouse: an animal model useful for studies on cognitive enhancers

The senescence-accelerated mouse (SAMP8) is a useful murine model of accelerated aging and learning deficiency. We examined bindings of [3H]pirenzepine, [3H]dizocilpine (MK-801), [3H]flunitrazepam, [3H]8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) and [3H]phorbol 12,13-dibutylate (PDBu) in SAMP8 brains, and compared them to those of SAMR1 (control). In the hippocampus of SAMP8 at 12 months, bindings of [3H]pirenzepine, [3H]MK-801, [3H]flunitrazepam, [3H]8-OH-DPAT and [3H]PDBu were significantly lower than those in SAMR1. In the cerebral cortex, bindings of [3H]pirenzepine, [3H]flunitrazepam and [3H]8-OH-DPAT were higher in SAMP8 than in SAMR1 at 12 months. [3H]PDBu binding was decreased in both the fractions of the membrane and cytosol in the hippocampus of SAMP8. The neurochemical findings presented here support behavioral and pharmacological findings that SAMP8 is a useful model of learning dysfunction and anxiety-deficiency. The usefulness of SAMP8 in studies on cognitive enhancers is also discussed.

Protective effect of carbidopa on hydroxyl radical generation in the rat striatum by dopamine

The effect of L-3,4-dihydroxyphenylalanine (L-DOPA) on the generation of hydroxyl free radicals (.OH) was investigated using striatal microdialysis technique. Salicylic acid in Ringer's solution (0.5 nmol.microliters-1.min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acids (DHBA) in the striatum. When L-DOPA (0.1 mM; 1 microliter.min-1) was infused in the rat brain, the level of 3,4-dihydroxyphenylacetic acid (DOPAC) gradually increased in a time-dependent manner. In addition, a marked elevation of DHBA was observed. However, in the presence of carbidopa, a decarboxylase inhibitor, the elevation in DHBA formation was not observed. These results suggest that carbidopa may suppress the .OH generation by dopamine (DA).

Synthesis and characterization of insulin-like growth factor-binding protein (IGFBP)-7. Recombinant human mac25 protein specifically binds IGF-I and -II

The mac25 cDNA was originally cloned from leptomeningial cells and subsequently reisolated through differential display as a sequence preferentially expressed in senescent human mammary epithelial cells. The deduced amino acid sequence of the human mac25 propeptide shares a 20-25% identity to human insulin-like growth factor-binding proteins (IGFBPs), suggesting that mac25 could be another member of the IGFBP family. In the present study, we have generated recombinant human mac25 (rh-mac25) in a baculovirus expression system and assessed its affinity for IGFs and have evaluated the pattern of expression of the mac25 gene in human tissues. Binding of 125I-IGF-I and 125I-IGF-II to rh-mac25 was demonstrated by Western ligand blotting after nondenaturing polyacrylamide gel electrophoresis and by affinity cross-linking with as little as 2 nM rh-mac25. Specificity of rh-mac25 binding to 125I-IGFs was demonstrated by competition for rh-mac25 binding with unlabeled IGFs, but not with [QAYLL]IGF-II analog, which has 100-fold less affinity for IGFBPs. In comparison with IGFBP-3, rh-mac25 has at least a 5-6-fold lower affinity for IGF-I and 20-25-fold lower affinity for IGF-II. mac25 mRNA was detectable in a wide range of normal human tissues, with decreased expression in breast, prostate, colon, and lung cancer cell lines. In conclusion, mac25 specifically binds IGFs and constitutes a new member of the IGFBP family, IGFBP-7. Its wider distribution in normal tissue and lower expression in several cancer cells indicate that IGFBP-7 may function as a growth-suppressing factor, as well as an IGF-binding protein.

Two signals are necessary for cell proliferation induced by a cytokine receptor gp130: involvement of STAT3 in anti-apoptosis

gp130 is a common signal transducer for the interleukin-6-related cytokines. To delineate the gp130-mediated growth signal, we established a series of pro-B cell lines expressing chimeric receptors composed of the extracellular domain of the granulocyte colony-stimulating factor receptor and the transmembrane and cytoplasmic domains of gp130. The second tyrosine (from the membrane) of gp130, which was required for the tyrosine phosphorylation of SHP-2, its association with GRB2, and activation of a MAP kinase, was essential for mitogenesis, but not for anti-apoptosis. On the other hand, the tyrosine in the YXXQ motifs essential for STAT3 activation was required for bcl-2 induction and anti-apoptosis. Furthermore, dominant-negative STAT3 inhibited anti-apoptosis. These data demonstrate that two distinct signals, mitogenesis and anti-apoptosis, are required for gp130-induced cell growth and that STAT3 is involved in anti-apoptosis.

[Primary biliary cirrhosis with polymyositis successfully treated with prednisolone and ursodeoxycholic acid]

A 65-year-old woman was given a diagnosis of polymyositis in April 1991. She was treated with prednisolone until December 1993, at which time muscle strength had increased and high blood pressure had developed. In May 1994 she was hospitalized for muscle weakness and mild liver dysfunction. Prednisolone was given and the levels of hepatobiliary enzymes decreased. Immunological examination revealed strongly positive results for anti-mitochondria antibody and M-2 antibody, which lead to the diagnosis of primary biliary cirrhosis. administration of ursodeoxycholic acid in addition to prednisolone was followed by normalization of liver function and a decrease in the production of the autoantibodies. Although polymyositis can be complicated by autoimmune diseases, reports of complication by primary biliary cirrhosis are rare, here we report that treatment with the combination of ursodeoxycholic acid and prednisolone was successful in a patient with liver dysfunction and primary biliary cirrhosis.