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Biomedical subjects

H Nakao

Publications and source records attributed to H Nakao.

At least 109 records · Page 6Linked to original sources
PubMed1994

Neurotrophic effects of annexin V on cultured neurons from embryonic rat brain.

Recombinant human annexin V showed survival promoting activity in embryonic rat neocortical and mesencephalic neurons in vitro. The neurotrophic effect was observed from a relatively low dose and in a dose-dependent manner. The neurotrophic activity of annexin V was completely blocked by anti-annexin V antibody. Northern blot analysis demonstrated that annexin V mRNA is expressed in non-neuronal cells in the CNS. These results suggest that annexin V plays certain roles in the CNS as a paracrine-type neurotrophic factor.

Amino Acid Sequence↗
PubMed1994

Intracellular free calcium level and its response to cAMP stimulation in developing Dictyostelium cells transformed with jellyfish apoaequorin cDNA.

A new method is described for measuring intracellular free calcium concentrations, [(Ca2+)i], in the cells of Dictyostelium discoideum transformed with apoaequorin cDNA of the jellyfish, Aequorea victoria. Aequorin, a calcium-specific indicator, was regenerated in vivo from apoaequorin produced in the cells by incubation with coelenterazine. The results showed that [(Ca2+)i] in developing cells markedly increases at the aggregation stage and again at the culmination stage after a temporary drop at the migration stage. Except for the vegetative stage, the cells at all stages of development exhibit a sharp transient increase in [(Ca2+)i] upon stimulation with a cAMP (50 nM) pulse, high responses being observed at the migration and culmination stages. Separated prestalk cells of migrating slugs contain more than twice as much [(Ca2+)i] and show three times as large a response to cAMP stimulation as prespore cells.

Aequorin↗
PubMed1994

Cell-cycle-dependent sorting in the development of Dictyostelium cells.

The sorting behavior of Dictyostelium discoideum Ax-2 cells and its relation to the cell-cycle phase at the onset of starvation were analyzed with reference to pattern formation, using beta-galactosidase as a cell marker and the temperature-shift method for cell synchronization. Cells transformed with the vector pAct15-Gal showed different sorting behavior during development when they were starved at different cell-cycle phases. Cells (T7) starved at the mid-late G2 phase (just before the PS-point from which cells enter the differentiation phase when starved) aggregated most rapidly and possibly functioned as aggregation centers, but were eventually sorted out to the posterior zone of migrating slugs. In contrast, T1 cells starved at the late G2 phase (just after the PS-point) exhibited slower aggregation compared with T7 cells. During further culture, T1 cells then sorted out to the apical tips of tipped aggregates and were located predominantly in the anterior zone of migrating slugs. Thus, T1 and T7 cells apparently interchange their positions in the cell masses during tip formation. The possible significance of cell-cycle-related sorting presented here is discussed, with special emphasis on pattern formation and cell differentiation.

Animals↗
PubMed1994

Reinfection with influenza B virus in children: analysis of the reinfection influenza B viruses.

Influenza B virus reinfection in Japanese children was studied epidemiologically during 1979-91 and virologically during 1985-91. During this investigation, there were four epidemics caused by influenza B viruses, each of which accompanied antigenic drift. Between the epidemics in 1987/88 and 1989/90, the viruses changed drastically, both genetically and antigenically. The minimum rate of reinfection with influenza B virus during the whole period was 3-25% depending on the influenza seasons. The antigens of primary and reinfection strains of influenza B virus isolated from 18 children during 1985-90, which covered three epidemic periods, were studied by haemagglutination inhibition tests. The results showed that the viruses isolated in the 1984/85 and 1987/88 influenza seasons, which belonged to the same lineage, were antigenically close, and reinfection occurred with these viruses. The results of amino-acid analysis of the HA1 polypeptide of these viruses corresponded with those of antigenic analysis. There were no specific amino-acid changes shared by the primary infection and reinfection influenza B viruses; the patients were infected with the viruses epidemic at that time.

Adolescent↗
PubMed1994

Cyclic thrombocytopenia associated with IgM anti-GPIIb-IIIa autoantibodies.

We studied a female patient with cyclic fluctuation in platelet count following splenectomy for autoimmune thrombocytopenia. The cyclical fluctuation appeared to be in phase with her menstrual cycle and her platelet count was low during menses. Bone marrow examinations performed at the peak as well as the bottom of the platelet count showed normal or increased numbers of megakaryocytes. The patient's platelet count increased rapidly after intravenous gamma-globulin (IVIgG) therapy, suggesting that a failure of platelet production is unlikely to account for the cycle. Platelet-associated IgM (PAIgM) was markedly elevated, whereas PAIgG was normal at any stage of the cycle. MACE assay demonstrated that PAIgM contained IgM anti-glycoprotein (GP) IIb-IIIa autoantibodies. Comparison between MACE assay using untreated and EDTA-treated platelets at 37 degrees C demonstrated that the platelet-associated IgM autoantibodies mainly recognized divalent cation-dependent conformation(s) of GPIIb-IIIa. No antibodies were, however, detected in her serum. The levels of IgM anti-GPIIb-IIIa showed an inverse relationship with the platelet count. In spite of the marked increase in platelet count after IVIgG, however, the levels of IgM anti-GPIIb-IIIa remained elevated. These findings suggest that platelet-associated IgM anti-GPIIb-IIIa autoantibodies are of pathogenic significance in this patient.

Autoantibodies↗
PubMed1994

Idiopathic infantile hypercalcemia discovered in the newborn period.

We report a male newborn with typical clinical signs of idiopathic infantile hypercalcemia (IIH); that is, hypercalcemia, hypercalciuria, an elfin face and nephrocalcinosis without giving Vitamin D3 supplementation to the patient. He had been treated with a vitamin D-free, low calcium milk and rectal administration of exogenous calcitonin (elcatonin). The latter seemed to be more effective as a treatment for IIH. The serum calcium level came within the normal range and the serum 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) level decreased from 101.5 to 75.6 pg/mL with the treatments mentioned above. These results suggest that a high serum concentration of 1,25(OH)2D3 is part of the pathogenesis of IIH. However, we were not able to clarify the pathogenesis of the high serum concentration of 1,25(OH)2D3.

Administration, Rectal↗
PubMed1994

Dictyostelium prespore-specific gene Dp87 encodes a sorus matrix protein.

In this paper we report on the characteristics of the product of a prespore-specific gene (Dp87) of Dictyostelium discoideum. Polyclonal antibody was made against a bacterially synthesized Dp87-encoded protein fragment. Using this antibody, the product was characterized by immunochemical and immunocytological methods. It was shown that the Dp87-encoded protein is a prespore-specific protein with a molecular mass of 83 kDa, which first appears at the standing slug stage and persists in mature fruiting bodies. Western blot studies revealed the presence of an additional 81 kDa protein prior to the appearance of the 83 kDa protein from the tipped aggregate to the standing slug stage, thus indicating the former to be a precursor protein. Immunocytochemical and immunoelectron microscopic studies showed that the protein is bound to ER at the early stages of development when only the 81 kDa protein is present. At the later stages when the 83 kDa protein predominates, however, it becomes localized in prespore-specific vacuoles (PSVs) and is associated with the inner fibrous material of PSVs, but not with the peripheral membranous material. This is in contrast to spore coat proteins, which are localized in PSVs from the beginning of their appearance and associated with both structures of PSVs. In mature fruiting bodies, most Dp87 protein is localized to the interspore space (matrix) of the sori, with some left on the surface of the stalk tube. Disruptants of the Dp87 gene were also produced. Although they contained neither 81 kDa nor 83 kDa protein, they showed no phenotypic defects as compared to the parental strain.

Animals↗
PubMed1994

Inhibition of temperature-dependent immobilization of fowl spermatozoa at body temperature by an increased intracellular pH.

Fowl sperm motility was measured by altering the extracellular pH (pHe) at 30 degrees C and 40 degrees C. At 30 degrees C, the motility of intact spermatozoa was vigorous in a medium in the wide pHe range of 7.3-10.1. In contrast, intact spermatozoa were almost immotile at 40 degrees C in medium below a pHe of 8.1. However, the motility could be restored by increasing the pHe; maximum motility was obtained in medium at pHe 9.4. Stimulation of the motility of demembranated spermatozoa at 40 degrees C was also observed with an increased pHe. However, demembranated spermatozoa at 40 degrees C that had been stimulated by increasing the pHe lost their motility when 1 mmol CaCl2 l-1 was added. Motility was restored by the subsequent addition of 2 mmol EGTA l-1. At a high pHe at 40 degrees C, the flagellar ATPase activity of crude dynein extract was not affected, regardless of the addition of CaCl2 or EGTA. The intracellular pH (pHi) of intact spermatozoa, estimated by measuring the accumulation of 9-aminoacridine fluorescence, increased with increasing pHe at both 30 degrees C and 40 degrees C. These results demonstrate that the reversible temperature-dependent immobilization of fowl spermatozoa at 40 degrees C is inhibited by an increased pHi. Furthermore, it is possible that the effects of the increased pHi may not act directly on dynein ATPase activity, but are mediated by a Ca(2+)-related substance(s) on the axoneme.

Animals↗
PubMed1994

T cell abnormalities in mixed connective tissue disease complicated with Klinefelter's syndrome.

We report a 28-year-old Japanese with Klinefelter's syndrome who developed mixed connective disease (MCTD) and Sjögren syndrome. Previously being well, he presented with Raynaud's phenomenon, dry eye, fever and polyarthralgia. Clinical examinations revealed anti-nRNP autoantibody, leukopenia and lung fibrosis. Then he was found to have Klinefelter's syndrome. Flow cytometric analysis showed a relative increase of peripheral CD8+ T lymphocytes carrying either HLA-DR or CD57. Lymphocyte IL-2 production induced in vitro by concanavalin A was decreased. Such T cell abnormalities may be implicated in the development of autoimmune disease in Klinefelter's syndrome.

Adult↗
PubMed1993

Evidence for superantigen production by Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis is an enteric pathogen that induces a variety of clinical symptoms, fever, scarlatiniform rash, diarrhea, vomiting, and arthritis. Characteristic histopathologic findings in Y. pseudotuberculosis infection such as lymphoid hyperplasia, typically seen in mesenteric lymph nodes, suggest that the stimulation of a large proportion of T lymphocytes may be involved in the pathogenesis of this infection. In this study, we assessed the mitogenic activity of culture supernatants of the clinical isolates of Y. pseudotuberculosis and investigated the mechanism by which these culture sups activate T cells. The culture sups, as well as partially purified fractions obtained by gel filtration, were found to selectively stimulate T cells bearing V beta 3, V beta 9, V beta 13.1, and V beta 13.2 compared with stimulation by anti-CD3. Furthermore, fibroblasts transfected with different HLA class II molecules, either HLA-DPw9, -DQw6, -DR1, or -DR4 Dw15, were capable of presenting Y. pseudotuberculosis culture supernatants to purified T cells. The T cell response to this sup was not restricted by donor HLA-DR types and was not neutralized by antibodies against the known staphylococcal superantigens, Staphylococcal enterotoxin (SE)A, SEB, SEC2, SED, SEE, and TSST1. These results suggest that Y. pseudotuberculosis produces superantigenic toxins that may mediate some of the systemic illnesses associated with infection by this organism.

Animals↗
PubMed1993

Heterogeneity in the molecular species of heat-stable enterotoxin of Vibrio cholerae non-O1 expressed by Escherichia coli carrying the cloned toxin gene.

The biological activity of the heat-stable enterotoxin of Vibrio cholerae non-O1 (NAG-ST) was found to be predominantly associated with the periplasmic extract (about four-fold higher than the culture supernatant) of a recombinant E. coli (JM109) strain carrying the NAG-ST toxin gene. Four molecular species of NAG-ST, two each from the periplasmic extract and culture supernatant of JM109, were purified. Amino acid sequence analysis of the four NAG-ST peptides isolated by HPLC revealed that they all differed from that of the mature 17-amino acid residue NAG-ST released by V. cholerae non-O1. The M(r)-values of the peptides obtained from the periplasmic extract were 4331 and 2785, while those recovered from the culture supernatant were 3154 and 2785. It thus appears that V. cholerae NAG-ST is synthesized as larger molecules in the recombinant E. coli strain. The differences in sizes of the exported NAG-ST molecule could relate to differences in the enzyme cleavage system between E. coli and V. cholerae.

Amino Acid Sequence↗
PubMed1993

Location on the evolutionary trees of the non-structural protein (NS) and neuraminidase (NA) genes of late human influenza A (H2N2) viruses: parental viruses of the NS and NA genes of Hong Kong influenza A (H3N2) viruses.

The nucleotide sequences of the non-structural protein (NS) and neuraminidase (NA) genes of human influenza A (H2N2) viruses isolated in 1967 and 1968 in Europe, Asia and North and South America were located on evolutionary trees in order to identify the parental virus of Hong Kong influenza A (H3N2) viruses, which appeared in the human population in 1968. From the evolutionary trees, the H2N2 viruses isolated during the 1967 to 1968 period were divided into two groups. Group I includes that A/Tokyo/3/67, A/Hachioji/1/67, A/Perg/1/68, A/Cordoba/522/67, A/Texas/2/68 and A/Berkeley/1/68 viruses, whereas group II includes the A/Georgia/1/67, A/England/10/67 and A/Poland/6/67 viruses. The NS and NA genes of Hong Kong H3N2 viruses isolated in 1968 were genetically closer to those of group II viruses and closest to those of A/Poland/6/67.

Base Sequence↗
PubMed1993

[Sporadic case of hemolytic uremic syndrome associated with verotoxin producing Escherichia coli O2:K1:H7].

Cases of enterohaemorrhagic Escherichia coli (EHEC) are being increasingly reported in Japan. Bacteriological isolation of EHEC has been a constant problem because the organism is shed for a short duration after onset on illness and generally during the prodromal stages. In order to ease the diagnosis of EHEC infections in this country, we have developed a LPS-based solid phase enzyme linked immunosorbent assay for serological diagnosis of the infection. Adequate knowledge on the prevalence of EHEC serogroups in Japan is mandatory for the success of such a diagnostic test. O157 is currently the prominent serogroup associated with EHEC infections in Japan followed by O111, O26 and O128 in that order of prevalence. In February 1992, a 1 year-old infant developed hemolytic uremic syndrome (HUS) 15 days later the prodrome of watery diarrhoea. Stool sample obtained on day 15 was cultured for detection of EHEC. Ten colonies of E. coli picked from MacConkey agar plate were examined by the polymerase chain reaction (PCR) using primers specific for both verotoxins (VT1 and VT2). Of the 10 colonies, only one was positive for the VT2 gene. The strain was confirmed to be cytotoxic on cultured Vero cells. The strain agglutinated with antisera of E. coli O2, K1 and with H7 serogroups. As of date, none of such strains of O2:K1:H7 EHEC has been reported in Japan. The patient's sera was found to be positive for antibodies against LPS from the homologous isolate as well as against VT2. The patient recovered uneventfully from HUS 40 days after the onset of the disease and was discharged from the hospital.

Antibodies, Bacterial↗
PubMed1993

Developmental regulation of transcription of a novel prespore-specific gene (Dp87) in Dictyostelium discoideum.

The Dp87 is a novel prespore specific gene of Dictyostelium discoideum which has a long open reading frame of 555 amino acids. The entire amino acid sequence had low but significant homology to the spore coat proteins, SP96 and SP70, of this organism. When a chimeric gene, containing a 1380 bp of the 5' upstream region of this gene fused with CAT gene, as reporter, was introduced into cells of this organism, it was expressed only in prespore cells of the slug. Transformation experiments, using chimeric genes, containing a series of 5' deletions of the upstream region, showed that -447 bp to -357 bp is an important cis-acting regulatory region for transcription. A nuclear factor(s) that specifically bind to this cis-acting region were detected from slug cell nuclei. Transformation experiments using a chimeric gene consisting of the 5' region between -666 bp and +149 bp of this gene, a beta-galactosidase reporter and an actin 8 terminator, showed that the reporter gene was expressed as early as in aggregation streams, indicating that Dp87 become transcribed a few hours earlier than the other prespore-specific genes so far reported. This was confirmed by northern hybridization detected using an image plate analyzer. The fact that cells expressing Dp87 appeared at random in aggregation streams gives solid support to the idea that position-independent differentiation of prespore and prestalk cells, followed by their sorting, brings about pattern formation in this organism.

Amino Acid Sequence↗
PubMed1992

Elevated serum manganese superoxide dismutase in acute leukemias.

We measured the serum levels of manganese-superoxide dismutase (Mn-SOD) in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Serum Mn-SOD level for normal subjects was 94.1 +/- 23.5 ng/ml (mean +/- S.D.), the levels for AML and ALL patients were 159.6 +/- 77.1 ng/ml and 154.4 +/- 77.0 ng/ml, respectively. The serum Mn-SOD levels were unrelated to individual intracellular Mn-SOD levels, but correlated well with serum lactate dehydrogenase values. Regression of the leukemia was accompanied by decrease in the serum level of Mn-SOD. Serum Mn-SOD may thus serve as a measure of the activity of the disease.

Enzyme-Linked Immunosorbent Assay↗