Biomedical subjects

M Okuma

Publications and source records attributed to M Okuma.

At least 91 records · Page 5Linked to original sources

PubMed1995

A maxi Cl- channel coupled to endothelin B receptors in the basolateral membrane of guinea-pig parietal cells.

1. To study endothelin (ET) receptors in guinea-pig stomach, ET-binding assays and in vitro autoradiography were performed on fundic cell suspensions and on sections of the fundus, respectively. ETA and ETB receptor subtypes were found to coexist in the parietal cells. 2. Endothelin 1 (ET-1) added to the (basolateral) bathing solution was found to activate noisy whole-cell Cl- currents within about 1 min in both single, isolated parietal cells and those within gastric glands obtained from the fundus. 3. ET-1-induced Cl- currents were rapidly blocked by a Cl- channel blocker (NPPB) added to the (basolateral) bathing solution in a concentration-dependent manner with a half-maximum inhibition concentration of 33 microM. 4. The anion selectivity sequence of the ET-1-induced conductance was I- > Br- > Cl- > F-, corresponding to Eisenman's sequence I. 5. Changes in extracellular pH between 5 and 8 did not affect the ET-1-induced activation of Cl- currents. 6. Similar activating effects were also observed with ET-3 and a specific ETB receptor agonist (IRL1620). An ETB receptor antagonist (IRL1720) prevented the ET-1 effect, whereas an ETA-selective antagonist (FR139317 or BQ123) failed to antagonize the ET-1 effect. 7. In the whole-cell mode, unitary Cl- channel events could be observed in association with ET-1-activated macroscopic currents. The single-channel conductances were around 200 and 350 pS at negative and positive membrane potentials, respectively. 8. It is concluded that gastric parietal cells of guinea-pig possess pH-insensitive 'maxi' Cl- channels coupled to ETB receptors in the basolateral membrane.

Animals↗

PubMed1995

Tumorigenicity of human T-cell leukemia virus type I-infected cell lines in severe combined immunodeficient mice and characterization of the cells proliferating in vivo.

The mechanism involved in leukemogenesis and neoplastic cell growth of adult T-cell leukemia (ATL) still remains unclear. We examined the tumorigenicity of human T-cell leukemia virus type I (HTLV-I)-infected cell lines in an in vivo cell proliferation model using severe combined immunodeficient (SCID) mice. Eleven HTLV-I-infected cell lines were injected into SCID mice and we found that 4 of them were capable of proliferating in SCID mice. Three of four transplantable cell lines are derived from the leukemic cell clone and 6 of 6 HTLV-I-infected cell lines of nonleukemic cell origin could not engraft in SCID mice. Interestingly, it was shown that some HTLV-I-infected and interleukin-2 (IL-2)-dependent cell lines could successfully engraft in SCID mice. The expression of IL-2 mRNA was not detected in these cell lines growing either in vivo or in vitro. HTLV-I viral products were not detected in 3 of 4 transplantable cell lines proliferating in vivo. Peripheral blood T cells immortalized by introduction of tax gene of HTLV-I were found to have no tumorigenic potential in SCID mice. These data suggest that (1) HTLV-I-infected cell lines of nonleukemic cell origin do not have enough leukemogenic changes to acquire the tumorigenic potential in SCID mice; (2) the IL-2 autocrine mechanism is not directly involved in the tumor cell growth; (3) viral gene expression is not needed for the maintenance of neoplastic cell growth; and (4) the expression of tax gene is not sufficient for the neoplastic cell growth in vivo.

Animals↗

PubMed1995

Effect of the antiretroviral agent hypericin on rat liver mitochondria.

The photosensitizing effect of hypericin (HY), an antiretroviral agent, on the functions of isolated rat liver mitochondria has been investigated. The respiratory control ratio (RCR), ADP/O and membrane potential of mitochondria were decreased by HY in a light-dependent manner. Uncoupled respiration of mitochondria in the presence of succinate was also inhibited by HY in a light-dependent manner. The ID50 of hypericin for these inhibitions was approximately 0.5 microM. These inhibitory effects of HY were not observed when photosensitization was conducted under anaerobic conditions and were not affected by desferrioxamine (DSF) or superoxide dismutase (SOD). Upon photosensitization of HY, mitochondria consumed oxygen in the absence of respiratory substrate with concomitant formation of thiobarbituric acid reactive substance (TBARS). The amount of oxygen consumed was 100-times greater than that of TBARS formed. The oxygen uptake was partially inhibited by NaN3, and formation of TBARS was inhibited by DSF. Upon photosensitization of HY in the presence of mitochondrial membranes, the electron spin resonance (ESR) signal of 2,2-dimethyl-5-hydroxy-1-pyrrolidinyloxyl (DMPO/.OH) was increased by a mechanism which was suppressed by DSF. An ESR signal for singlet oxygen bound to 2,5-dimethylfuran, 2,2,6,6-tetramethyl-4-piperidone (TEMP) was also detected under light in the presence of mitochondria. This signal of the TEMP-N-oxyl radical (TEMPO) was decreased by azide, which physically quenches singlet oxygen, but was increased by DSF. These results indicate that HY might inhibit mitochondrial functions by a type II photodynamic mechanism but that lipid peroxidation of biological membranes through an active oxygen-mediated photodynamic mechanism is not involved.

Animals↗

PubMed1995

Types of nuclear endonuclease activity capable of inducing internucleosomal DNA fragmentation are completely different between human CD34+ cells and their granulocytic descendants.

A hallmark of apoptosis is internucleosomal DNA fragmentation resulting from the activation of endonucleases. We characterized the endonuclease activity of human myeloid cell nuclei that cleaved their own nuclear chromatin to oligonucleosomal length fragments. Polymorphonuclear leukocytes (PMNs) of normal peripheral blood contained both Ca2+/Mg(2+)-dependent and DNase II-like acidic endonuclease activities in their nuclei. Immature myeloid cells of normal bone marrow at various stages of granulocytic maturation had similar nuclease activities. In contrast, a clear difference was shown in the circulating CD34+ cells, in that only Mg(2+)-dependent, Ca(2+)-independent endonuclease activity was detected. Consistent with these findings is the emergence of the Ca2+/Mg(2+)-dependent and acidic endonuclease concomitantly with the disappearance of the Mg(2+)-dependent endonuclease when CD34+ cells were induced to differentiate in vitro toward granulocytes. Leukemic cell lines of all lineages also had Mg(2+)-dependent nuclease activity. Our results suggest an association of the Mg(2+)-dependent endonuclease with hematopoietic progenitor cells and that the relative activities of the nuclear nuclease in human myeloid cells change substantially during granulocytic differentiation.

Antigens, CD↗

PubMed1995

Influence of spontaneous portosystemic collateral pathways on portal hemodynamics in living-related liver transplantation in children. Doppler ultrasonographic study.

We investigated the influence of spontaneous portosystemic collateral pathways on the portal hemodynamics and examined the necessity for ligating these vessels in pediatric liver transplantation from living donors. We assessed portal blood flow before, during, and after surgery in 82 pediatric recipients (mean age, 4.2 years), using Doppler ultrasonography. When blood flow in the reconstructed portal vein was decreased (< 10 ml/min/kg body weight) and portosystemic collaterals persisted during surgery, those vessels were ligated and Doppler flowmetry was examined again. Spontaneous portosystemic collaterals were detected at one or more sites in 67 patients before transplantation. These collaterals had been ligated in 17 patients before intraoperative flowmetry. Among the remaining 50 patients, initial Doppler studies revealed a decrease in portal blood flow in 22 patients. Nine patients had hepatofugal splenic venous flow and 6 had no significant flow signals from the intrahepatic portal vein. Ligation of collaterals resulted in a remarkable increase in portal blood flow in 20 patients, all of whom are alive. The remaining 2 patients died of graft failure due in part to portal hypoperfusion. On the other hand, the collaterals were not ligated in 24 patients because adequate portal blood flow was confirmed by intraoperative flowmetry. Postoperatively, flow signals from the unligated collateral vessels gradually diminished, but they still persisted in 3 patients at 12 months after transplantation. Hepatofugal blood flow through the portosystemic collateral pathways may persist after implantation of a normal graft. If the patent collaterals significantly reduce the effective portal blood flow, these vessels should be ligated in order to avoid graft failure.

Adolescent↗

PubMed1995

Differential regulation of protein-tyrosine phosphatases by integrin alpha IIb beta 3 through cytoskeletal reorganization and tyrosine phosphorylation in human platelets.

The major platelet integrin alpha IIb beta 3 (glycoprotein IIb-IIIa) has been implicated in the regulation of tyrosine phosphorylation and dephosphorylation in activated platelets. To investigate the mechanisms of the alpha IIb beta 3-dependent tyrosine dephosphorylation, normal platelets or thrombasthenic platelets lacking alpha IIb beta 3 were stimulated with thrombin and fractionated into Triton X-100-soluble or -insoluble subcellular matrices. We then examined the kinetics of the tyrosine-phosphorylated proteins and distribution of protein-tyrosine phosphatases in these fractions and whole cell lysates. First, alpha IIb beta 3-dependent tyrosine dephosphorylation was recovered mainly in the cytoskeleton with similar kinetics to the whole cell lysate. Second, protein-tyrosine phosphatase (PTP) 1B and its cleaved 42-kDa form were associated with the cytoskeleton in an aggregation-dependent manner, whereas association of PTP1C with the cytoskeleton was regulated differentially both by thrombin stimulation and by alpha IIb beta 3-mediated aggregation. Several calpain inhibitors did not affect either tyrosine phosphorylation and dephosphorylation or relocation of PTP1B, but they did inhibit cleavage of PTP1B. Cytochalasin D blocked relocation of both PTP1B and PTP1C but not PTP1B cleavage. SH-PTP2 was distributed in the other fractions than the cytoskeleton and showed no relocation on thrombin stimulation. Finally, the cytoskeleton-associated PTP1C became tyrosine-phosphorylated in an alpha IIb beta 3-mediated aggregation-dependent manner. Thus, integrin alpha IIb beta 3 was involved differentially in the regulation of PTP1B and PTP1C.

Adult↗

PubMed1995

High expression of c-kit in K562YO cells due to the prolonged half-life of its mRNA: the effects of modification with serine/threonine kinase signals.

We previously reported that the K562 cell line K562YO expressed a high level of the c-kit gene. In this study, we analyzed the mechanism of this expression and investigated the effects of the serine/threonine kinases such as protein kinase C (PKC) and cyclic adenosine 3',5'-monophosphate (cAMP)-dependent kinase (PKA) on it. The half-life of the c-kit mRNA in K562YO cells was greater than 10 hours, compared with 2 hours in the original K562 cells, which expressed a very low level of c-kit mRNA. This prolonged half-life can contribute to the high level of c-kit expression in K562YO cells. Cycloheximide (CHX), a protein synthesis inhibitor, caused increases in c-kit mRNA levels in K562YO cells. 12-O-tetradecanoylphorbol-13-acetate (TPA), by which PKC was activated at first and downregulated in a late phase, gradually decreased c-kit mRNA in K562YO cells until 9 hours and then returned to the control level 24 hours after treatment. TPA also rapidly decreased c-kit protein level on the membranes. In whole cells, c-kit protein was also decreased 6 hours after incubation with TPA. Calphostin C, a light-dependent PKC inhibitor, decreased c-kit mRNA levels within 30 minutes in a light-dependent manner. It also decreased c-kit protein in whole cells 2 hours after the addition. However, it increased the amount of c-kit protein on the cell surfaces. Dibutyryl cyclic AMP (dbc-AMP) increased c-kit mRNA as well as c-kit protein on membranes and in whole cells. Run-on transcriptional assay suggested that the agent (dbc-AMP) enhanced the transcription rate of the gene. These results suggest that c-kit protein on the membranes is downregulated by PKC activation and upregulated by PKC inhibition. In the whole cell lysate, c-kit proteins are decreased by PKC inhibition through downregulation of mRNA. On the other hand, the elevation of an intracellular cAMP level causes upregulation of both the mRNA and c-kit protein on membranes and in whole cells through enhanced transcription. Thus, c-kit gene expression is apparently modulated by PKC and PKA.

Bucladesine↗

PubMed1995

Light-dependent inhibition of protein kinase C and superoxide generation of neutrophils by hypericin, an antiretroviral agent.

Hypericin, a photosensitizing plant pigment, has antiretroviral activity. When exposed to light, the inhibition of Friend leukemia virus (FLV)-induced splenomegaly by hypericin was increased. The ID50 was decreased to less than 2.5 micrograms/mouse by exposure to tungsten light (29 x 10(-3) W/cm2 for 3 min). This pigment inhibited phorbol 12-myristate 13-acetate (PMA)-activated protein kinase C of rat brain in a light- and concentration-dependent manner. The ID50 of hypericin and the light intensity for inhibition of PKC were 0.1 microM under a constant light of 29 x 10(-3) W/cm2 for 3 min and 5 x 10(-3) W/cm2 in the presence of 1 microM hypericin for 3 min, respectively. The PMA-induced respiratory burst of neutrophils was inhibited in the light but stimulated in the dark by hypericin. The ID50 for inhibition of the respiratory burst was similar to that for inhibition of PKC. These results suggest that hypericin might inhibited PKC-mediated processes of intact cells, including PMA-induced superoxide generation of neutrophils by some light-dependent mechanism, and that this mechanism might underlie its light-dependent inhibition of FLV infection.

Animals↗

PubMed1995

Large molecule fraction of plasma separated with polyethylene glycol in treatment of chronic relapsing thrombotic thrombocytopenic purpura.

Plasma exchange and plasma infusion are effective in the treatment of patients with thrombotic thrombocytopenic purpura (TTP). It has been proposed that some component in normal plasma may be deficient in TTP patients. In this experiment normal plasma was fractionated and an effective fraction for the treatment of TTP was sought. Plasma was fractionated with 5% polyethylene glycol and a large molecule fraction was obtained which was composed mainly of proteins and lipoproteins with molecules larger than that of IgG. The fraction was dissolved in physiological saline and infused in two patients with chronic relapsing TTP who had been successfully treated periodically with plasma infusion. Peripheral platelet counts and serum LDH levels were measured, and the efficacy of the treatment was assessed. Infusion of the large molecule fraction elevated platelet counts and lowered the LDH level. However, the efficacy of the large molecule fraction was 25 to 50% that of plasma. Components in the fraction may have been inactivated partially during preparation. We propose that the large molecule fraction contains factors which are effective in some patients with TTP.

Adolescent↗

PubMed1995

Evaluation of protective effects of prostaglandin E1 on ischemic liver damage with in vivo 31P-MR spectroscopy.

The cytoprotective effect of prostaglandins (PG) was evaluated by in vivo 31P MR spectroscopy. Twenty rabbits were divided into two groups; the control group given physiological saline, and the PG group given prostaglandin E1 (0.5 microgram/kg/min). Each solution was infused for 8 min, after which complete hepatic ischemia was induced for 20 min, followed by reperfusion for 40 min. During ischemia, beta-ATP decreased to 23.6% and 42.3%, phosphomonoester increased to 260% and 200% of their initial values in the control and the PG groups, respectively. Inorganic phosphate also increased. After reperfusion, beta-ATP recovered to 65.2% and 96.5%, phosphomonoester to 130% and 110%, inorganic phosphate to 140% and 120% in the control and PG groups, respectively. The changes during ischemia were significantly smaller and the recoveries during reperfusion were more complete in the PG group. These results may confirm the cytoprotective effect of prostaglandins by in vivo 31P-MR spectroscopy.

Adenosine Triphosphate↗

PubMed1995

Recovery of graft circulation following percutaneous transluminal angioplasty for stenotic venous complications in pediatric liver transplantation: assessment with Doppler ultrasound.

Percutaneous transluminal angioplasty was performed for venous stenosis after living related liver transplantation in three children. Two of them had hepatic vein stenosis and one had stenosis of both the hepatic and portal veins. Progressive development of ascites and deterioration of liver function were found in all cases. Serial Doppler ultrasound studies showed that the flow velocity in the hepatic vein gradually decreased with a flattened velocity waveform, followed by a decrease in portal blood flow. After a successful hepatic vein angioplasty, the velocity in the hepatic and portal veins increased and the Doppler waveform in the hepatic vein became pulsatile in two cases. In the remaining case, a remarkable recovery of both graft perfusion and clinical findings was achieved via combined hepatic vein and portal vein angioplasty. We conclude that balloon angioplasty is an effective alternative to surgery for post-transplant vascular stenosis and that Doppler ultrasound is useful in monitoring graft circulation.

Angioplasty, Balloon↗

PubMed1995

Stable human T-lymphotropic virus type I carrier rates for 7 years among a teenaged blood donor cohort of 1986 in Kumamoto, Japan.

The human T-lymphotropic virus type I (HTLV-I) carrier rates for blood donors in Kumamoto, Kyushu, Japan for 8 years, 1986-1993, are currently available. The data show that 16-19-year-olds in 1986 and 20-29-year-olds in 1993 represent nearly the same cohort, because the median age in both groups is 24.5 years in 1993. Therefore, comparison of the HTLV-I positive rate for the two groups gives an estimate of the change in the rate over 7 years within the cohort. In males, 265 of 22,143 donors (1.20%) were seropositive for HTLV-I among 16-19-year-olds in 1986, and 214 were seropositive among 20,076 (1.07%) donors in 20-29-year-olds in 1993. In females, 203 were seropositive among 20,677 (0.98%) donors in 16-19-year-olds in 1986, and there 154 were seropositive among 18,660 (0.83%) donors in 20-29-year-olds in 1993. Thus, the seropositive rates declined in both sexes. However, the average annual rate of immigration to Kumamoto Prefecture was 2.37%. If seropositive rates for 20-29-year-olds in 1993 are adjusted for the dilution effect due to immigration (under the assumption that all immigrants were HTLV-I negative), the adjusted carrier rate for males is 1.26% and that for females is 0.98%. The adjusted carrier rates for both sexes are almost the same as those for 16-19-year-olds in 1986. This indicates that horizontal transmission was negligible for those in the cohort who were in their early reproductive period. Using all 8 year carrier rates for 16-19-year-olds and 20-29-year-olds, chronological changes of 20-29-year-olds, in the near future was estimated. The best goodness of fit model indicated that the HTLV-I carrier rate will decline exponentially, and that the rate will decrease by 50% approximately every 10 years for both sexes. It is probable that in recent years south-west Japan has lost the conditions that are favorable for HTLV-I endemicity and the virus will be virtually non-endemic within a few generations.

Adolescent↗

PubMed1995

Erythroid differentiation and growth inhibition of K562 cells by 2',5'-dideoxyadenosine: synergism with interferon-alpha.

We found that 2',5'-dideoxyadenosine (DDA), a P-site specific adenylate cyclase inhibitor, inhibited the growth of K562 cells and caused them to become benzidine positive. The continuous exposure of cells to DDA was needed to recruit cells for growth inhibition and differentiation. Fetal calf or human sera were also necessary for DDA to induce differentiation. DDA at a concentration of 1.5 mM with serum induced 98% of the cells to produce hemoglobin and inhibited their growth to 15% of that of the control. An increase of epsilon-globin mRNA and a decrease of c-myc and c-myb mRNA occurred only during differentiation in the presence of fetal calf serum (FCS). An incubation with DDA and interferon-alpha (IFN-alpha) or hemin synergistically induced more benzidine-positive cells than in the presence of DDA alone, although IFN-alpha did not trigger differentiation by itself. The erythroid differentiation and growth inhibition were, however, not related to a decreased intracellular cyclic AMP (cAMP) concentration induced by DDA. The simultaneous incubation with dibutyryl cyclic AMP (dbc-AMP) and DDA enhanced the effects of DDA. Adenine, a possible metabolite of DDA digestion by purine nucleoside phosphorylase (PNP), also induced erythroid differentiation in K562 cells. However, it did not act synergistically with IFN-alpha.

Adenine↗

PubMed1995

Vascular complications in living related liver transplantation detected with intraoperative and postoperative Doppler US.

BACKGROUND/AIMS: The purpose of this study was to clarify changes in the graft hemodynamics induced by vascular complications in living related liver transplantation. METHODS: This study included 46 pediatric recipients who underwent partial liver transplantation from living related donors. The blood flow was evaluated in the portal system, the hepatic artery and the hepatic vein with serial intra- and post-operative Doppler ultrasound (US). RESULTS: In 12 patients, intraoperative Doppler US showed a decrease in portal venous inflow (< 9 ml.min-1.kg-1) toward the liver graft and could act as a guide for ligation of collaterals in seven patients, portal re-construction in two, thrombectomy in one and relief of hepatic venous outflow obstruction in two for increasing the portal venous inflow. In five patients, intraoperative Doppler US showed poor arterial inflow, i.e. dampened arterial waveforms which involved both low pulsatility index (< 0.90) and low peak-systolic velocity (< 31 cm/s). In three of them, the waveform was more pulsatile after re-anastomosis or relief from stretching of the hepatic artery. The remaining two patients developed hepatic artery thrombosis. Most of the hepatic venous outflow obstruction (four of five patients) had flat waveforms, low flow velocity (< 10 cm/s) of the hepatic vein, and poor portal inflow (flow velocity < 14 cm/s). Postoperative Doppler US showed hepatic venous outflow obstruction in three patients, hepatic artery thrombosis in three (twice in one patient), portal vein stenosis in two and portal vein thrombosis in one. These complications were successfully managed with surgical procedures in three patients, transhepatic angioplasty in three and conservative treatments in four. Six patients died of non-vascular complications. CONCLUSIONS: Serial intra- and post-operative Doppler US was a useful technique for making an early diagnosis of abnormal hemodynamics of the graft circulation. Furthermore, intraoperative Doppler US could assess reconstructed vessels objectively and would reduce the incidence of vascular complications following transplantation.

Adolescent↗

PubMed1995

Class switch recombination of the immunoglobulin heavy chain gene frequently occurs in B-cell lymphomas associated with rearrangement of the BCL2 gene.

B-cell lymphomas, mainly follicular lymphomas, carrying a t(14;18) chromosomal translocation associated with rearrangement of the BCL2 gene and the immunoglobulin heavy chain (IGH) gene, share many similarities with germinal center B cells in the secondary lymphoid follicle. In the germinal center, antigen-stimulated B cells proliferate and differentiate while undergoing isotype class switching of their immunoglobulin heavy chains. To examine whether BCL2-positive lymphoma cells show class switch recombination similar to that in the germinal center B cells, we studied the genomic configurations of the IGH gene loci in 38 patients with B-cell lymphomas. Sixteen (80%) out of 20 patients with BCL2-positive lymphomas showed class switch recombination on translocated and/or productive IGH gene loci. Lymphoma cells from 7 of the 16 patients expressed the gamma-heavy chain on their surfaces, indicating functional class switching to the gamma-constant gene on the productive allele. By contrast, 6 (33%) of the 18 patients lacking the BCL2 rearrangements exhibited class switch recombination. Statistical analysis revealed that the BCL2-positive lymphomas underwent switch recombination on either allele at a significantly higher frequency than the BCL2-negative lymphomas (P = 0.0099). This indicates that follicular lymphoma, not only morphologically but also functionally, recapitulates the germinal center. We propose that the up-regulated BCL2 expression itself is capable of playing an important role in immunoglobulin class switching.

Gene Rearrangement↗

PubMed1995

Synchronous presentation of Epstein-Barr virus-associated Hodgkin's disease and adult T-cell leukemia/lymphoma (ATLL) in a patient from an endemic area of ATLL.

We report a patient from an endemic area of adult T-cell leukemia/lymphoma (ATLL), who developed lymphoma with features characteristic of Hodgkin's disease (HD). Large atypical Reed-Sternberg/Hodgkin's cells (RS/H cells) had a CD3-CD15+CD20-CD30+CD45RO- immunophenotype. Epstein-Barr virus (EBV) latent membrane protein and EBV-encoded small RNA were detected in the RS/H cells. The patient received C-MOPP/ABVD chemotherapy for the HD resulting in a partial response. However, relapse occurred and he died of disease progression associated with serious bacterial infection. Although serial lymph node biopsies revealed consistent presence of the EBV-positive RS/H cells, the background small lymphocytes showed progressive increase in pleomorphism and nuclear irregularity. The lymphocytes had the T-cell phenotype, CD3+CD4+CD7-CD8-. Southern blot analysis using DNA probes for the human T-cell lymphotrophic virus-I (HTLV-I) and the T-cell receptor beta-chain gene demonstrated expansion of the HTLV-I infected monoclonal T-cells with the disease progression. We concluded that the patient synchronously presented two independent lymphoproliferative disorders; EBV-associated HD and ATLL resulting from HTLV-I infection.

Antigens, CD↗

PubMed1995

Functional significance of platelet membrane glycoprotein p62 (GP VI), a putative collagen receptor.

We previously suggested that platelet 62 kDa protein (p62, GP VI) is a putative collagen receptor by the studies on platelets and antiplatelet antibody in a patient (YA) with idiopathic thrombocytopenic purpura (ITP) who showed defective collagen-induced platelet function. Herein, we confirm that p62/p57 (reduced/unreduced conditions) is a specific membrane protein recognized by YA antibody using an improved immunoprecipitation technique. To further study the functional role of this protein, a crude p57 fraction ('p57') was obtained from human platelets by serial chromatography including DEAE-Sepharose CL-6B and WGA-agarose followed by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). This 'p57' diminished the platelet-aggregating activity of collagen and of YA immunoglobulin G (IgG). N-terminal amino acid sequence analysis of 'p57' showed that it contained intercellular adhesion molecule 2 (ICAM-2). Immunoprecipitation experiments using platelet lysates and anti-ICAM-2 monoclonal antibody demonstrated that ICAM-2 molecules had a molecular weight similar to p62 on SDS-PAGE. However, ICAM-2 was also expressed on YA's p62-deficient platelets both on immunoprecipitation and flow cytometric analysis. Thus, ICAM-2 seems to be different from p62.

Amino Acid Sequence↗

PubMed1995

Radioimmunodetection of human leukemia with anti-interleukin-2 receptor antibody in severe combined immunodeficiency mice.

Anti-Tac monoclonal antibody recognizes human interleukin-2 receptor, which is overexpressed in leukemic cells of most adult T-cell leukemia (ATL) patients. To examine the potency of anti-Tac for targeting of ATL, biodistributions of intravenously administered 125I- and 111In-labeled anti-Tac were examined in severe combined immunodeficiency (SCID) mice inoculated with ATL cells. Significant amounts of radiolabeled anti-Tac were found in the spleen and thymus. The trafficking of ATL cells in SCID mice was detected using 111In-oxine-labeled ATL cells. These results were coincident with the histologically confirmed infiltration of ATL cells. The radiolabeled anti-Tac seemed potent for targeting of ATL.

Adult↗