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Biomedical subjects

T Kitani

Publications and source records attributed to T Kitani.

At least 91 records · Page 5Linked to original sources
PubMed1994

cDNA cloning and expression of human calmodulin-dependent protein kinase IV.

Calmodulin-dependent protein kinase IV (CaM-kinase IV) is a Ca(2+)-responsive multifunctional protein kinase which occurs abundantly in the brain and thymus. A human cDNA clone encoding CaM-kinase IV was isolated from a Jurkat cell cDNA library and its nucleotide sequence was determined. The cDNA sequence encoded a protein consisting of 473 amino acids with a molecular weight of 51,925. The nucleotide sequence for the coding region and the deduced amino acid sequence showed 81 and 80% identities with those of the rat enzyme, respectively. Western blot analysis, using a polyclonal antibody raised against the recombinant human CaM-kinase IV, which was expressed in Escherichia coli, revealed two bands corresponding in mobility to molecular weights of 60,000 and 61,000, respectively, in a Jurkat cell extract. The antibody also cross-reacted with both isoforms of CaM-kinase IV from rat cerebellum, the apparent molecular weights being 62,000 and 64,000, respectively.

Amino Acid Sequence↗
PubMed1994

Inactivation of Ca2+/calmodulin-dependent protein kinase II by Ca2+/calmodulin.

Incubation of calmodulin-dependent protein kinase II with Ca2+ and calmodulin resulted in a marked inactivation of the enzyme. Chelation of Ca2+ by EGTA or addition of calmodulin antagonists, W-7 or trifluoperazine, completely blocked this inactivation. The concentration required for the half-maximal inactivation, 127 microM, is three to four orders of magnitude higher than that for the half-maximal activation of the enzyme. The Ca2+/calmodulin-independent activity of the proteolytic fragment of the enzyme, whose calmodulin-binding site involved in the enzyme activation was deleted, was also decreased by incubation with Ca2+ and calmodulin. These results suggest that calmodulin-dependent protein kinase II possesses a second, low-affinity calmodulin-binding site, which is distinct from the calmodulin-binding site involved in the activation of the enzyme, and that the binding of calmodulin to the second binding site causes the inactivation of the enzyme. The inactivation by Ca2+/calmodulin was temperature-dependent. The addition of both 500 microM ADP and 10 mM MgCl2 markedly protected the enzyme against the inactivation, while such a marked protection was not observed after the addition of either of the two alone. The addition of 5 microM autocamtide-2, a synthetic substrate peptide containing the amino acid sequence of the autophosphorylation site (Thr286/Thr287 in alpha/beta, gamma, and delta isoforms) lying within the autoinhibitory domain, also protected the enzyme against the inactivation by Ca2+/calmodulin, while syntide-2, another synthetic substrate peptide corresponding to a phosphorylation site of glycogen synthase, did not protect it even at a concentration as high as 304 microM.

Animals↗
PubMed1994

Purification and characterization of Ca2+/calmodulin-dependent protein kinase IV kinase from rat brain.

Calmodulin-dependent protein kinase IV (CaM-kinase IV) kinase was recently discovered in the rat brain by its activity to activate the inactive recombinant CaM-kinase IV expressed in Escherichia coli [Okuno, S. and Fujisawa, H. (1993) J. Biochem. 114, 167-170]. In the present study, CaM-kinase IV kinase was purified approximately 2,000-fold from rat cerebral cortex by purification procedures including calmodulin affinity chromatography, and its properties were examined. The highly purified CaM-kinase IV kinase gave one major protein band corresponding to a molecular weight of about 66,000 upon SDS-PAGE. The purified CaM-kinase IV kinase phosphorylated and concomitantly activated CaM-kinase IV purified from rat brain as well as the recombinant kinase expressed in Escherichia coli in a Ca2+/calmodulin-dependent manner. The phosphorylation of CaM-kinase IV by CaM-kinase IV kinase occurred on only serine residue(s). Among a number of proteins, including several known to be phosphorylated by the various protein kinases tested, CaM-kinase IV was the best substrate for CaM-kinase IV kinase. Since syntide-2, a synthetic peptide known to be a good peptide substrate for calmodulin-dependent protein kinase II (CaM-kinase II), was a fairly good substrate for CaM-kinase IV kinase, some kinetic properties of CaM-kinase IV kinase were examined using syntide-2 as a substrate. The Km value for the peptide substrate in the presence of Ca2+/calmodulin was almost two orders of magnitude lower than that in its absence, although the Vmax value was almost the same in the presence and absence of Ca2+/calmodulin.

Amino Acid Sequence↗
PubMed1994

Prevalence of human herpesvirus 6 variants A and B in patients with chronic fatigue syndrome.

Peripheral blood mononuclear cells collected from 13 patients with chronic fatigue syndrome and 13 healthy controls were analyzed for the presence of human herpesvirus 6 (HHV-6) DNA by variant-specific polymerase chain reaction and dot blot hybridization. HHV-6 DNA was detected in 7 of 13 (53%) patients, and of those 7 patients, 4 were positive for HHV-6 variant A DNA and 3 were for variant B. No HHV-6 DNA was detected in the controls. Serum antibody titers to the late antigen and antibody prevalence to the early antigen of HHV-6 were significantly higher in the patient group. These results suggest active replication of HHV-6 in patients with chronic fatigue syndrome.

Antibodies, Viral↗
PubMed1994

[Clinical efficacy of arbekacin on MRSA infections with hematopoietic disorders. The Hanshin Study Group of Hematopoietic Disorders and Infections].

Arbekacin (ABK) was administered to 17 patients with MRSA infections that complicated underlying hematopoietic disorders, and the efficacy and safety were evaluated. The underlying diseases included acute myelocytic leukemia (8 cases), acute lymphocytic leukemia (1) myelodysplastic syndrome (3), chronic myelocytic leukemia (1), non-Hodgkin's lymphoma (2), Hodgkin's disease (1) and adult T cell leukemia (1). The infections consisted of septicemia (5 cases), pneumonia (4), upper respiratory tract infections (6) and urinary tract infections (2). ABK was administered by i.v. drip infusion in daily doses of 150-200 mg, given in two divided dosages. The therapeutic efficacies were: excellent in 2 (2 septicemias), good in 7 (1 septicemia, 4 upper respiratory infections, 2 urinary tract infections), fair in 2 (septicemia and pneumonia) and poor in 6 (1 septicemia, 3 pneumonias, 2 upper respiratory infections). As a side effect, reversible renal dysfunction was detected in four cases. Causative bacteria were isolated from six cases. They were all coagulase type II and MIC's of ABK were from 0.25 microgram/ml to 4.0 micrograms/ml. Arbekacin therapy was found to be effective even in patients with hematopoietic disorders accompanied by MRSA infections.

Adolescent↗
PubMed1993

Deficiency of the GPI anchor caused by a somatic mutation of the PIG-A gene in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria is an acquired hematopoietic disease characterized by abnormal blood cell populations in which the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor is deficient. Deficiency of surface expressions of GPI-anchored complement inhibitors leads to complement-mediated hemolysis. Here we report that PIG-A, which participates in the early step of GPI anchor biosynthesis, is the gene responsible for paroxysmal nocturnal hemoglobinuria. Affected granulocytes and B lymphocytes had the same somatic mutation of PIG-A, indicating their clonal origin from a multipotential hematopoietic stem cell. We localized PIG-A to the X chromosome, which accounts for expression of the recessive phenotype of the somatic mutation and the fact that the same one of the multiple biosynthetic steps is affected in all patients so far characterized.

B-Lymphocytes↗
PubMed1993

The cloning of PIG-A, a component in the early step of GPI-anchor biosynthesis.

The glycosylphosphatidylinositol (GPI) anchor is a membrane attachment structure of many proteins and occurs in a wide variety of eukaryotes from yeasts to mammals. The structure of the core of the GPI anchor is conserved in protozoa and mammals and so is its biosynthetic pathway. A complementary DNA encoding a human protein termed PIG-A (phosphatidylinositol glycan-class A) was cloned. PIG-A was necessary for synthesis of N-acetylglucosaminyl-phosphatidylinositol, the very early intermediate in GPI-anchor biosynthesis.

Amino Acid Sequence↗
PubMed1993

Deficient biosynthesis of N-acetylglucosaminyl-phosphatidylinositol, the first intermediate of glycosyl phosphatidylinositol anchor biosynthesis, in cell lines established from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a hemolytic disorder caused by a deficiency of biosynthesis of the glycosyl phosphatidylinositol (GPI) anchor, but the biochemical defect is not completely understood. In the present study, we have analyzed affected cell lines established recently from two Japanese patients with PNH. Two lines of evidence indicate that these cells do not synthesize N-acetylglucosaminyl-phosphatidylinositol, the first intermediate in the GPI anchor biosynthesis. First, somatic cell hybridization analysis using Thy-1-deficient murine thymoma cell lines with known biochemical defects as fusion partners showed that the PNH cell lines belong to complementation class A, which is known not to synthesize N-acetylglucosaminyl-phosphatidylinositol. Second, analysis of in vitro glycolipid biosynthesis demonstrated that cell lysates of these PNH cell lines in fact did not support biosynthesis of N-acetylglucosaminyl-phosphatidylinositol. Thus, we have characterized for the first time the exact biochemical defect leading to PNH.

Cells, Cultured↗
PubMed1993

Hairy cells from hairy cell leukemia patients presenting with pronounced polyclonal hypergammaglobulinemia secrete a factor enhancing IgG synthesis.

We studied the immunological function of hairy cells from hairy cell leukemia (HCL) patients presenting with pronounced polyclonal hypergammaglobulinemia (PPH). Hairy cell conditioned medium (HCCM) obtained from HCL patients with PPH augmented IgG production by normal peripheral blood mononuclear cells in a dose-dependent fashion, while HCCM from patients without PPH had no effect on IgG production. HCCM from the patients with PPH failed to enhance IgG synthesis by T cell-depleted mononuclear cells. Separation of T and B cells by a 0.4-microns membrane as well as monoclonal antibodies to HLA-DR and CD3 molecules prevented HCCM-dependent IgG synthesis. No B cell growth factor activity, interleukin-1, or interleukin-6 was detected in the HCCM. On examination by fractionation of the HCCM, IgG-inducing activity was detected in the fractions of 5000 to 8000 Da. These results indicate that hairy cells from HCL patients with PPH secrete a factor inducing IgG synthesis, and that the induction of IgG synthesis by the factor requires T-B cell interactions involving T cell receptor/CD3 complex and MHC class II antigens. This factor may play an important role in the development of PPH.

B-Lymphocytes↗
PubMed1993

Augmented induction by dexamethasone of metallothionein IIa messenger ribonucleic acid in fibroblasts from a patient with cortisol hyperreactive syndrome.

Northern blot analysis was used to investigate the effect of dexamethasone (Dex) or zinc on messenger RNA (mRNA) levels of metallothionein-IIa (MT-IIa) in fibroblasts from a patient with cortisol hyperreactive syndrome and from three normal subjects. Dex was seen to increase MT-IIa mRNA levels and brought them to a maximum after 12 h. Zinc also increased the levels of MT-IIa mRNA and brought them to a maximum at 8 h after the addition. Dex as well as zinc caused a dose-related increase in MT-IIa mRNA levels. Dex had a maximal inductive effect on MT-IIa at a concentration of 10(-6) mol/L and zinc at a concentration of 10(-4) mol/L. There was no significant difference in the levels of basal expression of the MT-IIa gene between the patient's and normal fibroblasts. But in three separate experiments induction of MT-IIa gene by Dex obtained for the patient's fibroblasts was almost twice as much as that for normal fibroblasts. On the other hand, there were no significant difference in induction by zinc between the patient's and normal fibroblasts. These data indicated that the patient's cells were hyperreactive to glucocorticoids as seen from the effect of Dex on the MT-IIa mRNA levels.

Adrenal Glands↗
PubMed1993

Splenic lymphoma with villous lymphocytes with CD5+, CD11c+ B-cell phenotype.

A 64-year-old male suffered from splenomegaly without lymphadenopathy. His WBC count on admission was 6.1 x 10(9)/l with 55% abnormal lymphocytes. No monoclonal gammopathy was detected. Abnormal cells shown in films usually had relatively abundant cytoplasm with serrated edges. Under phase-contrast microscopy, the cells displayed short, needle-like processes. The immunophenotype of peripheral blood mononuclear cells were CD19+, CD20+, CD11c+, FMC7+, CD5+, CD10-, CD25- and SIg+. The spleen histology showed a distinctive pattern of white pulp infiltration by abnormal lymphocytes with features of plasma cell differentiation. These findings were compatible with the features of splenic lymphoma with villous lymphocytes.

Antigens, CD↗
PubMed1993

Predominance of a distinct subtype of hairy cell leukemia in Japan.

Forty Japanese patients with hairy cell leukemia (HCL) were reviewed. Nine cases were diagnosed as typical HCL, and two cases had the features of HCL variant (prolymphocytic variant). The remaining 29 cases (72.5%) differed morphologically and hematologically from the other two groups in that they usually had a moderately high leukocyte count (average 27.9 x 10(3)/microliters), and abnormal cells showing a densely stained round nucleus and an inconspicuous nucleolus. Tartrate-resistant acid phosphatase reaction was weak, and their cells exhibited generally smooth or slightly irregular, cellular outlines in smears. The cells showed weak expression of surface immunoglobulin G (IgG) with kappa-chain predominance. CD25 antigen was not detected. Some of these findings resemble those of B-cell chronic lymphocytic leukemia, but the patients also had several important features of HCL. They had splenomegaly without significant lymphadenopathy. The abnormal cells were CD20+, CD11c+ and showed typical 'hairy morphology' under phase-contrast and scanning electron microscopy. Furthermore, spleen sections revealed diffuse infiltration by the abnormal cells in the red pulp. From these findings, we speculated that this group of patients constitute a distinct subtype of HCL which is commonly seen in Japan. We propose to term the disease as HCL Japanese variant.

Acid Phosphatase↗
PubMed1993

[Multiple myeloma and adhesion molecules].

The physiological role of fibronectin (FN) on the human plasma cells were examined using three PC cell lines, FR4ds, OPM1 and OPM1ds. FR4ds was reactive with anti-VLA-alpha 4 and anti-alpha 5. In contrast, OPM1 and OPM1ds were not reactive with anti-VLA-alpha 5. FN induced spreading in FR4ds and OPM1ds. Albumin blocked these spreadings. FR4ds with mature plasma cell phenotype of alpha 4+ and alpha 5+ was more sensitive for FN than OPM1 and OPM1ds with immature phenotype of alpha 4+ and alpha 5-. Spreading cells proliferated more than floating cells. All these cell lines showed chemotaxis toward FN. alpha 5+ FR4ds was more sensitive for FN than OPM1 and OPM1ds with alpha 5- phenotype. These new abilities of PC of spreading and chemotaxis we found are summarized to be an affinity to organs. It is likely that alpha 4+ and alpha 5- PC with low affinity to organs are stored in peripheral blood as a result. We examined the chemotaxtic activity of myeloma cells in bone marrow and these in pleural effusions in a patient with multiple myeloma. These cells in pleural effusions showed more chemotaxic activity than these in bone marrow. FN induced growth, production of Ig, and motility of PC, which resulted in the augmentation of humoral immunity.

Bone Marrow Cells↗
PubMed1993

[New protocols for myeloma chemotherapy plus IFN alpha].

In two consecutive studies of a pilot study and a multicenter trial 16 patients and 61 patients, respectively, with multiple myeloma were treated with the combination chemotherapy (CMVM regimen; the same intermittent high dose dexamethasone as in VAD regimen, MCNU bolus injection of 1.2mg/m2 on day 1, melphalan 12mg/day on days 1-6) plus IFN alpha (HLBI 300MU every day or two) to assess the efficacy and the toxicity of this protocol. Both studies were achieved in the same regimen except for initial 12 days administration of IFN alpha in the multicenter trial. The treatment was repeated 3 times every 6-8 weeks. Complete remission (CR) in which serum and urine M protein disappeared and myeloma cells in bone marrow were eradicated was obtained in 6 in 16 patients (37.5%) in the pilot study and 16 in 61 patients (26.2%) in the multicenter trial. CR plus PR was 68.8% and 68.9% in two studies. The achievement of CR in such high proportion of patients may exhibit a significant advance in the myeloma therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Deficient surface expression of glycosylphosphatidylinositol-anchored proteins in B cell lines established from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired type hemolytic disorder. Hematopoietic cells of patients with PNH are deficient in glycosylphosphatidylinositol (GPI) anchored membrane proteins. Since some membrane-bound complement inhibitors, such as CD59 and decay accelerating factor (DAF), are GPI anchored proteins, abnormal cells from patients with PNH are sensitive to complement attack. Their myeloid and erythroid cells are affected more than their lymphoid cells. Patients whose B cells were severely deficient in GPI anchored proteins were chosen to establish cell lines by Epstein-Barr virus mediated transformation. The lines established (SS-1-, TK-1-, and TK-14- cell lines) had the following characteristics of PNH. First, GPI anchored proteins were completely absent from the surface of SS-1- and TK-14- cells, and were expressed at very low levels on TK-1- cells, whereas polypeptide anchored proteins were normally expressed on these three lines. Secondly, DAF mRNAs of the SS-1- cell line were qualitatively and quantitatively indistinguishable from those of a control, wild-type cell line. Third, pro-CD59 and pro-DAF molecules were detected intracellularly in these cell lines, their pro-CD59 being smaller and more hydrophilic than that from a wild-type cell line. These cell lines should be useful in further studies on the pathogenesis of PNH.

Antigens, CD↗