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Biomedical subjects

S Asano

Publications and source records attributed to S Asano.

At least 361 records · Page 20Linked to original sources
PubMed1991

Thermostable alanine racemase of Bacillus stearothermophilus. Construction and expression of active fragmentary enzyme.

Limited proteolysis studies on alanine racemase suggested that the enzyme subunit is composed of two domains (Galakatos, N. G., and Walsh, C. T. (1987) Biochemistry 26, 8475-8480). We have constructed a mutant gene that tandemly encodes the two polypeptides of the Bacillus stearothermophilus enzyme subunit cleaved at the position corresponding to the predicted hinge region. The mutant gene product purified was shown to be composed of two sets of the two polypeptide fragments and was immunologically identical to the wild-type enzyme. The mutant enzyme, i.e. the fragmentary alanine racemase, was active in both directions of the racemization of alanine. The maximum velocity (Vmax) was about half that of the wild-type enzyme, and the Km value was about double. Absorption and circular dichroism spectra of the fragmentary enzyme were similar to those of the wild-type enzyme. An attempt was made to separately express in Escherichia coli a single polypeptide corresponding to each domain, but no protein reactive with the antibody against the wild-type alanine racemase was produced. Therefore, it is suggested that the two polypeptide fragments can fold into an active structure only when they are co-translated and that they correspond to structural folding units in the parental polypeptide chain.

Alanine Racemase↗
PubMed1991

Necrotizing lymphadenitis: a clinicopathological and immunohistochemical study of four familial cases and five recurrent cases.

We report the clinicopathological and immunohistological findings of nine cases of necrotizing lymphadenitis, consisting of four cases of familial infection and five cases of recurrence. Fever, cervical lymphadenopathy, leucopenia and swelling of the tonsils are characteristic clinical findings. Morphological features of the lymph nodes include the presence of immunoblasts, plasmacytoid T cells, histiocytes and macrophages, the latter with phagocytized nuclear debris derived from degenerated lymphocytes. However, granulocytes are generally absent. Ultrastructurally, tubuloreticular structures are observed not only in lymphoid cells, but in vascular endothelial cells. Immunological studies of peripheral blood using monoclonal antibodies disclose that CD 8+ (Leu 2a+; suppressor/cytotoxic) cells predominate at the onset, but they gradually decrease with the clinical course and the ratio of CD 4+: CD 8+ (helper:suppressor) increases as the disease progresses. However, in the affected lymph nodes, CD4+ (Leu 2a+: helper/inducer) cells often increase with the clinical progression, but the ratio of CD 4+:CD 8+ in the lymph nodes does not correlate with clinical progression. In addition, Ki-67+CD 8+ cells are more often seen than Ki-67+CD 4+ cells. It is suggested that necrotizing lymphadenitis is an infectious disease in which CD 4+ cells are disrupted and CD 8+ cells undergo transformation to blastoid cells. This results in a change in the ratio of T subsets.

Adolescent↗
PubMed1991

Clinical effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on various types of neutropenia including cyclic neutropenia.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was investigated for its clinical efficacy in the treatment of various types of neutropenia (3 cases with idiopathic neutropenia of suspected drug induction, 5 cases with idiopathic neutropenia of other origin, and 2 cases with cyclic neutropenia). Treatment with glycosylated rhG-CSF produced in the Chinese Hamster Ovary cells at dose levels of 2-5 micrograms/kg/day caused rapid increases of neutrophil counts associated with an improvement of the infection. In cyclic neutropenia patients, marked reduction in the duration of the neutropenic period was observed with rhG-CSF administration started before the period. Intercurrent stomatitis, which occurred in 1 patient, was markedly milder as compared to a previous episode which occurred during an untreated neutropenic period. The treatment of rhG-CSF was well tolerated and no adverse events were observed, nor was there any detectable anti-rhG-CSF antibody in any patients studied; hence the clinical use of rhG-CSF is considered to be safe. These results suggest beneficial effects of rhG-CSF on the recovery of neutrophil counts in cyclic and other types of idiopathic neutropenias, as well as for the treatment of neutropenia-associated infection.

Adolescent↗
PubMed1991

Several new approaches to improvement of alpha interferon therapy in chronic myelogenous leukaemia.

Several basic experimental and clinical studies were carried out in an attempt to improve the efficacy of alpha interferon therapy for chronic myelogenous leukaemia (CML). First, the combined use of hydroxyurea (HU) and interferon (500-1000 mg daily) in interferon-resistant cases facilitated maintenance of reduced leucocyte production, or a reduction in the dose of interferon, although suppression of Philadelphia chromosome (Ph1)-positive clones was not observed in most cases. In order to try and decrease the rate of lymphoblastic crisis during the course of interferon therapy, we recently added methotrexate (MTX) (10-15 mg, weekly) to the treatment protocol. Since then, no lymphoblastic crisis has been observed. Second, the in vitro expression of alpha interferon-stimulated gene (ISG) mRNA was shown to be markedly decreased in granulocytes of one representative interferon-resistant case, compared to that in granulocytes of the three interferon-sensitive cases. Interestingly, it was found that the transcriptional activity in this case became almost normal when the blood granulocytes were controlled by the addition of HU. These findings suggest that the in vitro transcriptional assay of ISG mRNA may be clinically useful for predicting alpha interferon efficacy. Third, when genetically manipulated, alpha interferon-producing NIH/3T3 cells were co-transplanted using diffusion chambers into nude mice bearing a CML cell line, KU812, the CML tumour growth was shown to be markedly suppressed. This experimental model for alpha interferon replacement gene therapy suggests some directions for future studies on interferon therapy.

Animals↗
PubMed1991

Human granulocyte colony-stimulating factor: its basic aspects and clinical applications.

Human granulocyte colony-stimulating factor (G-CSF), a 20 KD glycoprotein consisting of 174 amino acids, is one of the physiological regulators mainly produced by endothelial cells, monocytes-macrophages and fibroblasts, under various stimulations such as infections. The molecule specifically and markedly stimulates the production of neutrophils associated with an expansion of the hematopoietic stem cells/progenitor cells and elevates the functional activities of neutrophils. Under favor of the unique biological activities, recombinant human G-CSF (rhG-CSF) has now become an epoch-making agent for the purposes of reduction of bacterial/fungal infections, particularly in neutropenias of various causes, increased dose intensity of chemotherapeutic drugs in cancers, and solving various problems in hematopoietic stem cell transplantation.

Amino Acid Sequence↗
PubMed1991

A phase II trial of recombinant human granulocyte colony-stimulating factor in the myelodysplastic syndromes.

We conducted a phase II study of the intravenous administration of a glycosylated recombinant human granulocyte colony-stimulating factor (rhG-CSF) for 7-14 d in 41 patients with the myelodysplastic syndromes (MDS). Administration of rhG-CSF elicited striking rises in both leucocyte and neutrophil counts in the majority of the patients irrespective of the FAB subtypes of MDS. The rises in neutrophil counts were dose dependent and 5 micrograms/kg/d of rhG-CSF yielded approximately an 8-fold increase in neutrophil counts. Leucocytes and neutrophil counts started to increase shortly after the first injection of 5 micrograms/kg, was maintained at significantly elevated levels during 14 d of treatment, and returned to the pretreatment levels within several days following discontinuation of rhG-CSF. The action of rhG-CSF was specific for neutrophils since leucocytosis was due exclusively to neutrophilic increase associated with an increased marrow myeloid maturation. There were no consistent changes in the monocyte, eosinophil, lymphocyte, platelet or reticulocyte counts. After treatment, the percentage of marrow blast cells was reduced in eight of 13 evaluable patients with refractory anaemia with an excess of blasts (RAEB) or RAEB in transformation (RAEB-t). No patients developed acute leukaemia during the treatment or in the immediate follow-up period. The treatment was well tolerated with only minimal toxicity. The results suggest that rhG-CSF is a safe and effective way to promptly improve neutropenia in MDS patients.

Adolescent↗
PubMed1991

Monocytoid B lymphocytes and epithelioid cell clusters in abscess-forming granulomatous lymphadenitis. With special reference to cat scratch disease.

In order to clarify the appearance of monocytoid B lymphocytes (MBLs) in abscess-forming granulomatous lymphadenitis (AGL) and the relation between AGL and cat-scratch disease (CSD), 48 cases of AGL were studied histologically. MBLs were present in about 50% of AGL cases. Warthin-Starry (WS) silver stain-positive bacteria, which are the causative agent of CSD, were present in 52.4% of AGL cases with MBLs and 59.2% of AGL cases without MBLs. The appearance of MBLs in AGL was not related to various clinical features, including disease interval from initial lymphadenopathy to lymph node biopsy. Histologically, epithelioid cell clusters appeared in about 70% of MBL-positive AGL cases, but were not observed in MBL-negative AGL. Therefore, a close interaction between MBLs and epithelioid cells in AGL is suggested, and we emphasize that the histological features of some AGL cases resemble those of toxoplasmic lymphadenitis.

Abscess↗
PubMed1991

Regulation of mRNA levels of alkaline phosphatase gene in neutrophilic granulocytes by granulocyte colony-stimulating factor and retinoic acid.

We examined steady-state levels of mRNA for alkaline phosphatase in neutrophils (NAP) treated with granulocyte colony-stimulating factor (G-CSF). The amount of mRNA for NAP was shown to increase after 6 hours of culture with G-CSF when no increase in NAP activity was yet observed, and the transcript was the greatest after 20-24 h of culture with G-CSF. Treatment of neutrophils with both G-CSF and retinoic acid augmented the amount of mRNA for NAP over the amount obtained by G-CSF alone, which was most marked at 24 h. These results show that both G-CSF-mediated NAP induction and its potentiation by retinoic acid are due to the increased levels of mRNA for NAP.

Alkaline Phosphatase↗
PubMed1991

[The effect of recombinant human granulocyte colony-stimulating factor (rG-CSF) on childhood neutropenias].

The clinical effect of recombinant human granulocyte colony-stimulating factor (rG-CSF), produced by Chinese hamster ovary cells, was studied in 27 patients with childhood neutropenias. The sample consisted of 8 patients with congenital neutropenia (Kostmann type), 9 with neutropenia with miscellaneous causes (5 chronic benign, 2 associated with hypogammaglobulinemia, 1 drug-induced, and 1 hypoplastic type), 3 with cyclic neutropenia, and 7 with severe aplastic anemia. The rG-CSF was given subcutaneously (or in a few cases intravenously) at a dose of 2 micrograms/kg/day for 7 days and 5 micrograms/kg/day for additional 7 to 28 days in cases with poor response. The rG-CSF was effective in 18 of 27 cases (67%). Patients with congenital neutropenia and aplastic anemia responded less frequently and poorly. The mean level of absolute neutrophil counts of 8 congenital neutropenia cases increased from 88/microliters to 2,718/microliters. That of 9 miscellaneous cases changed from 189/microliters to 7,224/microliters at a dose of 2 micrograms/kg/day. In 7 aplastic anemia cases pretreatment level of 220/microliters rose to 851/microliters, usually after increasing the dose up to 5 micrograms/kg/day. The rG-CSF was apparently effective in 3 cases of cyclic neutropenia. In any type of neutropenia, the effect was largely transient; after the discontinuation of rG-CSF, the absolute neutrophil counts tended to decrease to pretreatment levels within 1 to 2 weeks. The G-CSF was well tolerated, and only one case with mild lumbago and another with minimal elevation of transaminases were observed. We conclude that the rG-CSF can be effective for treating various types of childhood neutropenia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Clinical evaluation of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in autologous bone marrow transplantation].

We administered recombinant human granulocyte colony-stimulating factor (rhG-CSF) at 5 micrograms/kg/day by intravenous drip infusion for 21 consecutive days in autologous bone marrow transplanted patients. The period of posttransplant neutropenia was markedly shortened by the rhG-CSF treatment; mean days required for neutrophil recovery (greater than 500/mm3) of 14.3 days in the rhG-CSF group (n = 21) versus 27.8 days in the historical control group (n = 11). More importantly, the numbers of febrile days between day 15 and day 28 were found to be fewer in the rG-CSF group than in control group. These effects were obtained without delay in the recovery of other blood cell series and without any side effect. We conclude that the posttransplant use of the rhG-CSF is beneficial for prevention and treatment of infectious complications after autologous bone marrow transplantation.

Adolescent↗
PubMed1991

[Hematological effect of 14 days treatment of recombinant human granulocyte colony-stimulating factor for neutropenia in myelodysplastic syndromes].

Nineteen patients with myelodysplastic syndromes (MDS) were treated with a glycosylated recombinant granulocyte colony-stimulating factor (rG-CSF) for improvement of neutropenia. rG-CSF was administrated intravenously at a dose of 5 micrograms/kg/day for 14 consecutive days. Most of patients responded to rG-CSF and an approximately 10 fold increase of the peak neutrophil counts was observed. The neutrophil counts were maintained at high level during the treatment period and returned to pretreatment levels several days after stopping rG-CSF. Consistent with the recovery of neutrophil, infectious complications improved in many cases. Effects of rG-CSF were confined to neutrophils, sparing blast cells and other blood cells. Eruption was observed in one patient as toxicity. We conclude that rG-CSF therapy is effective in improving neutropenia with MDS patients.

Adult↗
PubMed1990

Reversible inhibitions of gastric H+,K(+)-ATPase by scopadulcic acid B and diacetyl scopadol. New biochemical tools of H+,K(+)-ATPase.

Scopadulcic acid B (SA-B), a novel diterpenoid, is a main ingredient of the Paraguayan traditional medicinal herb "Typychá kuratú (Scoparia dulcis L.). SA-B and its debenzoyl derivative, diacetyl scopadol (DAS), specifically inhibit ATP hydrolysis of gastric H+,K(+)-ATPase. Both compounds inhibit the K(+)-dependent dephosphorylation step of the enzyme without any effect on the phosphorylation step. SA-B is a mixed-type inhibitor with respect to the activating cation, K+. SA-B lowers the affinity of H+,K(+)-ATPase to K+ and decreases the maximal velocity of ATP hydrolysis, whereas DAS is an uncompetitive inhibitor with respect to K+. Furthermore, the effects of SA-B and DAS on conformational states of the ATPase were studied by measuring the changes in the fluorescence intensity of the fluorescein isothiocyanate-labeled enzyme. The fluorescence study shows that SA-B primarily binds to the E2K form in the presence of Mg2+ and stabilizes the form and that DAS stabilizes the E2PK form. Therefore, the chemical modification of SA-B, debenzoylation, induced the changes in the pattern of inhibition of H+,K(+)-ATPase. Furthermore, the inhibition mechanisms of SA-B and DAS were different from those of omeprazole, which is an irreversible inhibitor, and SCH 28080, which is a reversible, competitive inhibitor with respect to K+. DAS also inhibited the K(+)-dependent p-nitrophenyl phosphatase activity, and the inhibition was competitive with respect to K+, indicating that the K(+)-dependent p-nitrophenylphosphatase activity does not represent the partial reaction step of H+,K(+)-ATPase.

Adenosine Triphosphatases↗