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Biomedical subjects

T Kitani

Publications and source records attributed to T Kitani.

At least 19 recordsLinked to original sources

Lack of effects of oxolinic acid on spermatogenesis in young adult and aged Wistar rats.

Prolonged treatment with oxolinic acid is known to elevate serum luteinizing hormone (LH) levels, resulting in induction of Leydig cell tumors in rats. In a carcinogenicity study of the compound, tubular atrophy of the testis was also increased, suggesting that oxolinic acid might affect spermatogenesis. The present study was therefore performed using rats of different ages with a particular focus on seminiferous tubule alteration and its relation to Leydig cell proliferation. Young adult (7 weeks of age) and aged (52 weeks of age) males of the Wistar strain were administered oxolinic acid at dietary concentrations of 0 (basal diet), 300, 1000 or 3000 ppm for 4 (all groups), 13 (0 and 3000 ppm groups), 26 (0 and 3000 ppm groups), or 52 weeks (0 and 3000 ppm groups of aged rats). Serum LH levels were elevated in both young adult and aged animals treated with 3000 ppm at most examined time points. While testosterone levels were also increased at the early time points in young adult, this was not the case in older animals. Elevation of the incidences of foci and/or focal hyperplasia of Leydig cells was noted but was only slight limited to aged rats treated with 3000 ppm after 26 weeks. Furthermore, it did not appear to be related to seminiferous tubular alteration. No treatment-related histopathological abnormalities could be detected in any treatment group, and morphometrical stage analysis of spermatogenesis conducted for the control and 3000 ppm-treated groups demonstrated no lesions. These results provide strong evidence that prolonged oxolinic treatment does not directly induce testicular toxicity or altered spermatogenesis in either young adult or aged rats, except for slight increase of Leydig cell proliferative lesions caused by elevated serum LH levels. Aged rats might have higher sensitivity than young adults to the effects of oxolinic acid on proliferative lesions of Leydig cells.

Aging↗

Immunohistochemical localization of Ca(2+)/calmodulin-dependent protein kinase kinase beta in the rat central nervous system.

We examined regional and intracellular distribution of Ca(2+)/calmodulin-dependent protein kinase kinase beta (CaM-KK beta), which activated Ca(2+)/calmodulin-dependent protein kinase I and IV (CaM-K I and IV) immunohistochemically in the central nervous system of the rat by light and electron microscopy. Although most neurons in the brain and spinal cord exhibited the immunoreactivity, no labeled neurons were observed in the globus pallidus or entopeduncular nucleus, and only a small number of neurons showed weak immunoreactivity in the substantia nigra pars reticulata. In general, the immunoreactivity was observed both in the cytoplasm and cellular nucleus, although the immunoreactivity was not found in the cellular nucleus in some large neurons such as in the mesencephalic trigeminal nucleus, lateral vestibular nucleus or gigant cellular reticular formation. As to motoneurons of the cranial nerve nuclei and the anterior horn of the spinal cord, they revealed the immunoreactivity both in the cytoplasm and nucleus. The reaction product appeared as fine granules in the cytoplasm and nucleus under light microscopy. Electron microscopic observations confirmed that the reaction product was localized mainly on the Golgi apparatus or on the nuclear chromatin. Immunolabeling for antibody against CaM-KK beta was discussed with the distribution of CaM-K I, IV and another CaM-KK, CaM-KK alpha, in the central nervous system.

Animals↗

Anti-prothrombin antibodies combined with lupus anti-coagulant activity is an essential risk factor for venous thromboembolism in patients with systemic lupus erythematosus.

Anti-prothrombin antibodies (anti-prothrombin) and anti-beta2-glycoprotein I antibodies (anti-beta2-GP I) are the most common and characterized anti-phospholipid antibodies (aPL) detected using specific enzyme-linked immunosorbent assay (ELISA) systems. Recently, lupus anti-coagulant (LA) activity detected by a phospholipid-dependent coagulation assay was reported to be associated with anti-prothrombin and/or anti-beta2-GP I. Here we show that the co-existence of IgG anti-prothrombin and LA activity might be an essential risk factor for venous thromboembolism (VTE) in patients with systemic lupus erythematosus (SLE). We examined not only the levels of antibodies to prothrombin and anti-beta2-GP I (both IgG and IgM isotypes) using an ELISA system, but also LA activity detected using both diluted Russell's viper venom time (dRVVT) and STACLOT LA test in 124 patients with SLE. The SLE patients were divided into four groups according to the results of ELISA and LA assay results for each aPL: group A, ELISA+ and LA+ group B, ELISA+ and LA-; group C, ELISA- and LA+ group D, ELISA- and LA-. Regarding IgG anti-prothrombin, the prevalence of VTE was significantly higher in group A (16/35 cases, 45.7%, P < 0.001, Fisher's exact probability test) than in the other groups (B, 2/30, 6.7%; C, 1/22, 4.5%; D, 1/37, 2.7%). With respect to IgM anti-prothrombin and IgG or IgM anti-beta2-GP I, the prevalence of VTE was higher in both groups A and C than in group D, but no statistical difference in prevalence was found between groups A and C. Multivariate logistic regression analysis of risk factors for VTE confirmed that the co-existence of IgG anti-prothrombin and LA activity was the only significant risk factor for VTE (odds ratio, 19.13; 95% confidence intervals, 4.74-77.18).

Adolescent↗

Substrate specificity of Ca(2+)/calmodulin-dependent protein kinase phosphatase: kinetic studies using synthetic phosphopeptides as model substrates.

Ca(2+)/calmodulin-dependent protein kinase phosphatase (CaMKPase) dephosphorylates and regulates multifunctional Ca(2+)/calmodulin-dependent protein kinases. In order to elucidate the mechanism of substrate recognition by CaMKPase, we chemically synthesized a variety of phosphopeptide analogs and carried out kinetic analysis using them as CaMKPase substrates. This is the first report using systematically synthesized phosphopeptides as substrates for kinetic studies on substrate specificities of protein Ser/Thr phosphatases. CaMKPase was shown to be a protein Ser/Thr phosphatase having a strong preference for a phospho-Thr residue. A Pro residue adjacent to the dephosphorylation site on the C-terminal side and acidic clusters around the dephosphorylation site had detrimental effects on dephosphorylation by CaMKPase. Deletion analysis of a model substrate peptide revealed that the minimal length of the substrate peptide was only 2 to 3 amino acid residues including the dephosphorylation site. The residues on the C-terminal side of the dephosphorylation site were not essential for dephosphorylation, whereas the residue adjacent to the dephosphorylation site on the N-terminal side was essential. Ala-scanning analysis suggested that CaMKPase did not recognize a specific motif around the dephosphorylation site. Myosin light chain phosphorylated by protein kinase C and Erk2 phosphorylated by MEK1 were poor substrates for CaMKPase, while a synthetic phosphopeptide corresponding to the sequence around the phosphorylation site of the former was not dephosphorylated by CaMKPase but that of the latter was fairly good substrate. These data suggest that substrate specificity of CaMKPase is determined by higher-order structure of the substrate protein rather than by the primary structure around its dephosphorylation site. Use of phosphopeptide substrates also revealed that poly-L-lysine, an activator for CaMKPase, activated the enzyme mainly through increase in the V(max) values.

Amino Acid Sequence↗

Regulation of Ca(2+)/calmodulin-dependent protein kinase kinase alpha by cAMP-dependent protein kinase: I. Biochemical analysis.

Ca(2+)/calmodulin-dependent protein kinases (CaM-kinases) I and IV are activated upon phosphorylation of their Thr(177) and Thr(196), respectively, by the upstream Ca(2+)/calmodulin-dependent protein kinases CaM-kinase kinase alpha and beta, and deactivated upon dephosphorylation by protein phosphatases such as CaM-kinase phosphatase. Recent studies demonstrated that the activity of CaM-kinase kinase alpha is decreased upon phosphorylation by cAMP-dependent protein kinase (PKA), and the relationship between the inhibition and phosphorylation of CaM-kinase kinase alpha by PKA has been studied. In the present study, we demonstrate that the activity of CaM-kinase kinase alpha toward PKIV peptide, which contains the sequence surrounding Thr(196) of CaM-kinase IV, is increased by incubation with PKA in the presence of Ca(2+)/calmodulin but decreased in its absence, while the activity toward CaM-kinase IV is decreased by incubation with PKA in both the presence and absence of Ca(2+)/calmodulin. Six phosphorylation sites on CaM-kinase kinase alpha, Ser(24) for autophosphorylation, and Ser(52), Ser(74), Thr(108), Ser(458), and Ser(475) for phosphorylation by PKA, were identified by amino acid sequence analysis of the phosphopeptides purified from the tryptic digest of the phosphorylated enzymes. The presence of Ca(2+)/calmodulin suppresses phosphorylation on Ser(52), Ser(74), Thr(108), and Ser(458) by PKA, but accelerates phosphorylation on Ser(475). The changes in the activity of the enzyme upon phosphorylation appear to occur as a result of conformational changes induced by phosphorylation on several sites.

Adenosine Triphosphate↗

Regulation of Ca(2+)/calmodulin-dependent protein kinase kinase alpha by cAMP-dependent protein kinase: II. Mutational analysis.

We previously reported that rat brain Ca(2+)/calmodulin-dependent protein kinase (CaM-kinase) IV is inactivated by cAMP-dependent protein kinase (PKA) [Kameshita, I. and Fujisawa, H. (1991) Biochem. Biophys. Res. Commun. 180, 191-196]. In the preceding paper, we demonstrated that changes in the activity of CaM-kinase IV by PKA results from the phosphorylation of CaM-kinase kinase alpha by PKA and identified six phosphorylation sites, Ser(24) for autophosphorylation, and Ser(52), Ser(74), Thr(108), Ser(458), and Ser(475) for phosphorylation by PKA. In the present study, a causal relationship between the phosphorylation and change in the activity toward PKIV peptide has been studied using mutant enzymes with amino acid substitutions at the six phosphorylation sites. The following conclusions can be drawn from the experimental results: (i) Phosphorylation of Ser74 and/or unidentified sites causes an increase in activity; (ii) phosphorylation of Thr(108) or Ser(458) causes a decrease in the activity; (iii) the inhibitory effect of the phosphorylation of Thr(108) is canceled by the stimulatory effect of the phosphorylation, but that of Ser(458) is not; and (iv) the inhibitory effects of Thr(108) and Ser(458) are synergistic. In contrast to the activity toward PKIV peptide, the activity toward CaM-kinase IV appears to be decreased by the phosphorylation of Thr(108), but not significantly affected by the phosphorylation of Ser(458).

Adenosine Triphosphate↗

Identification and characterization of CaMKP-N, nuclear calmodulin-dependent protein kinase phosphatase.

Calmodulin-dependent protein kinase phosphatase (CaMKP) dephosphorylates and concomitantly deactivates multifunctional Ca(2+)/calmodulin-dependent protein kinases (CaMKs), such as CaMKI, CaMKII, and CaMKIV. In the present study, a nuclear CaMKP-related protein, CaMKP-N, was identified. This protein consisted of 757 amino acid residues with a calculated molecular weight of 84,176. Recombinant CaMKP-N dephosphorylated CaMKIV. The activity of CaMKP-N requires Mn(2+) ions and is stimulated by polycations. Transiently expressed CaMKP-N in COS-7 cells was localized in the nucleus. This finding together with previous reports regarding localization of CaMKs indicates that CaMKP-N dephosphorylates CaMKIV and nuclear CaMKII, whereas CaMKP dephosphorylates CaMKI and cytosolic CaMKII.

Amino Acid Sequence↗

Immunohistochemical study of the distribution of Ca(2+)/calmodulin-dependent protein kinase phosphatase in the rat central nervous system.

Distribution of Ca(2+)/calmodulin-dependent protein kinase phosphatase (CaM-K Pase) which dephosphorylate multifunctional Ca(2+)/calmodulin-dependent protein kinases (CaM-kinases) in the rat brain and spinal cord were examined immunohistochemically by using an antibody against this enzyme. CaM-K Pase was localized only in the cytoplasm as has been investigated in PC 12 cells, and was never observed in the nucleus. Immunostainability varied from cell group to cell group. Mitral cells in the olfactory bulb, pyramidal neurons in the fifth layer of the cerebral cortex, hippocampal and striatal interneurons, dorsal and ventral pallidal, entopeduncular, and the reticular part of the substantia nigra neurons were intensely immunolabeled. Motoneurons in all the cranial nerve nuclei and the anterior horn of the spinal cord also revealed intense immunolabeling. On the contrary, pyramidal neurons in the Ammon's horn of the hippocampal formation, granule cells in the olfactory bulb, dentate gyrus and cerebellar cortex, Purkinje cells, neurons in the medial habenular nucleus and the inferior olivary nucleus have not shown immunoreactivity. Axons in the white matter or nerve root of the cranial nerve nuclei were immunolabeled. Glial cells in the white matter also showed immunostaining. Because the substrate of CaM-K Pase is multifunctional CaM-kinase II, I and IV, localization of each CaM-kinase was compared with that of CaM-K Pase. The distribution of CaM-K Pase and these CaM-kinases was found to overlap in various regions in the brain and spinal cord. It was concluded, therefore, that CaM-K Pase could regulate the activity of these CaM-kinases by dephosphorylation, when they existed together in neurons.

Animals↗

Detection of small populations of CD59-deficient erythrocytes in patients with aplastic anemia or myelodysplastic syndrome and normal individuals.

To detect a small population of blood cells with a deficiency of glycosyl phosphatidylinositol (GPI)-anchored protein, we evaluated the expression of CD59 by flow cytometry on one million erythrocytes, which is about 100 times more than the number of erythrocytes tested by our standard immunoassay. Blood samples from healthy volunteers, patients with aplastic anemia (AA), and patients with myelodysplastic syndrome (MDS), who all showed no detectable GPI deficiency by the standard assay, were investigated. The numbers of CD59-deficient erythrocytes were 5 to 145/10(6) erythrocytes in the healthy volunteers (mean 29.2), and one of the volunteers had an increase in the deficient cells exceeding the mean + 3 SD (141.7), a normal limit. A CD59-deficient population was detected in 6 of the 21 (28.6%) patients with AA and 5 of the 18 (27.8%) patients with MDS. The new assay was performed again in 5 of these 11 patients and the normal individual who had the CD59-deficient populations at 6 and 12 months after the initial study. The number of deficient cells gradually increased in 1 patient with MDS (from 511 to 2892/10(6) erythrocytes), while the numbers of the other 4 patients showed a tendency to decline, although the deficient populations were repeatedly detected on most of the occasions. Changes in the number of the deficient cells were also seen in the healthy volunteer, but they were rather rapid; the numbers changed from 145 to 5661 and then to 18/10(6) erythrocytes within 3 months. The CD59 assay used in this study is easy to perform and enabled us to detect less than 1% GPI-deficient cells.

Adolescent↗

Induction therapy consisting of alternating cycles of ranimustine, vincristine, melphalan, dexamethasone and interferon alpha (ROAD-IN) and a randomized comparison of interferon alpha maintenance in multiple myeloma: a co-operative study in Japan.

This pilot study evaluated the efficacy of a new combination chemotherapy with a newly developed nitrosourea derivative ranimustine and evaluated the efficacy of interferon alpha (IFN-alpha) maintenance in previously untreated patients with multiple myeloma (MM). The induction therapy (ROAD-IN) was a 6-week regimen consisting of chemotherapy with ranimustine, vincristine (Oncovin), melphalan (Alkeran) and dexamethasone starting on day 1 and IFN-alpha, which was administered three times weekly for 3 weeks starting on day 22. This was repeated for three cycles. The responders were subsequently randomized into two groups that received or did not receive IFN-alpha as maintenance therapy. Of the 164 patients registered, 161 were evaluated. An objective response to induction therapy was seen in 75% of patients; complete remission (CR) in 38 (24%) and partial remission (PR) in 82 (51%). The median survival for all patients was 3.6 years from registration. The survival of responders (CR + PR) was significantly better than that of non-responders (median survival 4.3 years vs. 1.4 years; 7-year survival rate 32% vs. 9%; P < 0.0001). The IFN-alpha maintenance did not show any advantage for either response duration or survival. This pilot study demonstrated that a comparatively short period of induction therapy with the ROAD-IN regimen produced a rather high response rate and a similar survival rate to those achieved with other longer induction regimens, and that good responders to the initial therapy survived significantly longer than non-responders.

Antineoplastic Combined Chemotherapy Protocols↗

Studies on the phosphorylation of protein kinase B by Ca(2+)/calmodulin-dependent protein kinases.

Protein kinase B (PKB) was recently reported to be activated on the phosphorylation of Thr(308) by Ca(2+)/calmodulin-dependent protein kinase kinase alpha (CaM-kinase kinase alpha), suggesting that PKB was regulated through not only the phosphoinositide 3-kinase pathway but also the Ca(2+)/calmodulin protein kinase pathway. The activation of PKB by CaM-kinase kinase alpha was as high as 300-fold after incubation for 30 min under the phosphorylation conditions, and still increased thereafter, suggesting that the maximal activation of PKB on phosphorylation of the Thr(308) residue is several hundred fold. On the other hand, the V(max) value of CaM-kinase kinase alpha for the phosphorylation of PKB was more than two orders of magnitude lower than that for CaM-kinase IV, although the K(m) values for PKB and CaM-kinase IV were not significantly different, raising the question of whether or not PKB is a physiological substrate of CaM-kinase kinase alpha. Besides CaM-kinase kinase alpha, CaM-kinase II also remarkably activated PKB. However, the specific activities of CaM-kinase kinase alpha and CaM-kinase II as to the activation of PKB were more than three orders of magnitude lower than that of 3-phosphoinositide-dependent protein kinase 1 (PDK1).

Animals↗

Blastic transformation of splenic lymphoma with villous lymphocytes after a well-controlled chronic phase of more than 10 years.

A 30-year-old Japanese man with splenomegaly and lymphocytosis was examined in 1985. Blood analysis revealed that some of the lymphocytes had short-surface villi with polar distribution. The cells showed Ig lambda+, CD5+, CD11c+, CD19+, CD22+, CD23+, CD24+, FMC7+ phenotype. A small M peak was detected in the serum. Splenic lymphoma with villous lymphocytes (SLVL) was diagnosed on the basis of these findings. Remission was induced and was maintained with low-dose chlorambucil for more than 10 years. In 1996, the patient developed splenomegaly and lymphadenopathy with "B" symptoms and a high serum lactase dehydrogenase (LDH) level. Large blastoid cells with prominent nucleoli were observed in the bone marrow; later, a small number appeared in the peripheral blood. The bone marrow cells showed a complex chromosomal abnormality involving del(7)(q32). Southern blot analysis of immunoglobulin gene rearrangements in SLVL cells that had been cryopreserved in 1986 and of bone marrow cells in 1996 showed 2 rearranged bands in each cell sample; 1 band showed identical sizes in the 2 samples, and the other showed different sizes. These findings suggest that the blastoid cells were derived from SLVL cells through transformation. After this transformation, the disease followed a highly aggressive course. Various chemotherapeutic agents had little effect, and the patient died 3 months later.

Adult↗

Assessment of alkaline phosphatase on the surface membrane of neutrophils by immunofluorescence.

Expression of alkaline phosphatase (ALP) on the surface membrane of neutrophils (mNAP) was studied by immunofluorescence using an anti-ALP monoclonal antibody. Fluorescent intensity distribution of mNAP was analyzed using FACS (fluorescence-activated cell sorter). The mean fluorescent intensity (MFI) of the mNAP in this assay was well correlated with the neutrophil ALP (NAP) score demonstrated cytochemically (r = 0.832). mNAP levels in various hematological disorders were evaluated by % mNAP+ cells and MFI. The levels in aplastic anemia and polycythemia vera were significantly higher, and in chronic myelocytic leukemia and paroxysmal nocturnal hemoglobinuria (PNH), the levels were significantly lower compared with the levels in healthy volunteers. Two-color immunofluorescence with anti-ALP and anti-CD16 showed that the PNH clone was essentially negative for mNAP, whereas residual normal neutrophils (CD16+) had levels slightly higher than those in normal individuals. Highly reproducible results were obtained in the blood samples which were stored at 4 degrees C for at least 24 hr without any treatment prior to immunofluorescent staining. No degradation of fluorescent intensity was seen 4 days after staining and fixation. The mNAP assay is simple, without subjective evaluation for quantification, and is useful for differential diagnosis of hematological disorders.

Alkaline Phosphatase↗

CD59-deficient blood cells and PIG-A gene abnormalities in Japanese patients with aplastic anaemia.

Patients with aplastic anaemia (AA) frequently develop paroxysmal nocturnal haemoglobinuria (PNH) as a late complication. We investigated the frequency of the development of PNH features including a glycosyl phosphatidylinositol (GPI) anchoring defect in 73 Japanese patients with AA. A deficient expression of CD59 was found on erythrocytes and/or granulocytes in 21/73 (28.8%) of the patients. A Ham/sugar water test was positive in 13/21 patients. We also examined mutations of the PIG-A gene in 11 patients with CD59 deficiency. A heteroduplex analysis detected PIG-A gene abnormality in 10/11 patients tested. Nucleotide sequencing was performed in six patients and identified eight mutations including three mutations in one patient. The mutations of the PIG-A gene were all different and included two single-base insertions, one single-base deletion, two two-base deletions, and one each of eight-base insertion and nine- and ten-base deletions. All mutations but one caused frameshifts. Our findings indicate that a high proportion of Japanese patients with severe AA have a GPI-anchoring defect and that the PIG-A gene is mutated in the AA patients who had a GPI deficiency. We found no significant difference in the pattern of the PIG-A gene mutation between the AA patients with a GPI deficiency and those with de novo PNH.

Adolescent↗

Clinical experiences in Sakai City Hospital during the massive outbreak of enterohemorrhagic Escherichia coli O157 infections in Sakai City, 1996.

In the middle of July, 1996, a massive outbreak of hemorrhagic colitis (HC) occurred among elementary schoolchildren in Sakai city. This is the most widespread outbreak of O157 infection ever experienced to our knowledge. Lunch foods supplied in the elementary schools in Sakai were contaminated by Escherichia coli (E. coli) O157. One hundred and twenty-one cases developed hemolytic uremic syndrome (HUS) from 12,680 symptomatic patients, including putative secondary infections, and three girls died during this outbreak. Sakai City Hospital is one of the core medical facilities in this community; hence, 425 children with HC were treated at the hospital. Antibiotics were used extensively on all patients. Among them, 12 children developed HUS. All 425 children, including the patients with HUS, recovered without significant sequelae. In the present paper, the clinical experiences during this massive outbreak of E. coli O157 infection in Sakai City Hospital are described.

Anti-Bacterial Agents↗

Molecular cloning of Ca2+/calmodulin-dependent protein kinase phosphatase.

Calmodulin-dependent protein kinase (CaM-kinase) phosphatase dephosphorylates and concomitantly deactivates CaM-kinase II activated upon autophosphorylation, and CaM-kinases IV and I activated upon phosphorylation by CaM-kinase kinase [Ishida, I., Okuno, S., Kitani, T., Kameshita, I., and Fujisawa, H. (1998) Biochem. Biophys. Res. Commun. 253, 159-163], suggesting that CaM-kinase phosphatase plays important roles in the function of Ca2+ in the cell, because the three multifunctional CaM-kinases (CaM-kinases I, II, and IV) are thought to be the key enzymes in the Ca2+-signaling system. In the present study, cDNA for CaM-kinase phosphatase was cloned from a rat brain cDNA library. The coded protein consisted of 450 amino acids with a molecular weight of 49, 165. Western blot analysis showed the ubiquitous tissue distribution of CaM-kinase phosphatase. Immunocytochemical analysis revealed that CaM-kinase phosphatase is evenly distributed outside the nucleus in a cell.

Amino Acid Sequence↗

Borna disease virus infection in two family clusters of patients with chronic fatigue syndrome.

A high rate of Borna disease virus (BDV) infection has been demonstrated in patients with chronic fatigue syndrome (CFS). Herein, we focused on BDV infection in two family clusters of patients with CFS: a father, mother, two sons and one daughter (family #1); and a father, mother, two daughters and one son (family #2). All members, except for the elder son in family #1 and the father and son in family #2, were diagnosed with CFS. The results supported that all the family members with CFS were infected with BDV, as evidenced by the presence of antibodies to viral p40, p24 and/or gp18 and BDV p24 RNA in peripheral blood mononuclear cells. The healthy members, except for the father of family #2 who was positive for antibody to p24, were all negative by both assays. Follow-up studies in family #1 continued to reveal BDV antibodies and BDV RNA, except in the mother, who lost the RNA upon slight recovery from the disease.

Amino Acid Sequence↗