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Biomedical subjects

S Muramatsu

Publications and source records attributed to S Muramatsu.

At least 127 records · Page 7Linked to original sources
PubMed1990

Nucleotide sequence of the region encompassing the int gene of a cryptic prophage and the dna Y gene flanked by a curved DNA sequence of Escherichia coli K12.

The nucleotide sequence of a 2.5 kb region encompassing a curved DNA segment (BENT-9) randomly cloned from the total Escherichia coli chromosome was determined. This region was found to contain the dna Y gene encoding a transfer RNA. The curved DNA structure was demonstrated to be located just upstream of the dna Y promoter. The results of sequencing further revealed that the int gene of a cryptic prophage, qsr', which has been shown to be present in the E. coli genome, is located next to the dna Y gene.

Amino Acid Sequence↗
PubMed1990

Induction of antitumor activity in macrophages by mycoplasmas in concert with interferon.

The in vitro growth of tumor cells infected with mycoplasmas was suppressed by macrophages pretreated with interferon (IFN), but the growth of mycoplasma-free tumor cells was not suppressed. Pretreatment of macrophages with IFN plus mycoplasmas or their soluble factors either simultaneously or sequentially, IFN first and mycoplasmas second, but not in the reverse order, was effective in activating macrophages to suppress the growth of mycoplasma-free tumor cells. Macrophages from C3H/HeJ mice (which respond only slightly to lipopolysaccharide) were activated by IFN plus mycoplasmas or their soluble factor, and their action was not influenced by the addition of a lipopolysaccharide-neutralizing agent, polymyxin B. These results suggest that the macrophage-activating agent in mycoplasmas does not mimic lipopolysaccharide. The administration of mycoplasmas plus IFN to mice with ascitic or solid tumors resulted in the reduction of tumor growth. The survival rate of tumor-bearing mice was improved by the administration of mycoplasmas, and this was synergistically enhanced by the addition of IFN. These results indicate (a) that mycoplasmas can be useful as a biological response modifier, and (b) that care should be taken to prevent contamination with mycoplasmas in experiments on macrophage activation.

Animals↗
PubMed1990

Electrophysiological study of dyskinesia produced by microinjection of picrotoxin into the striatum of the rat.

The neuronal mechanism of dyskinesia of the contralateral forelimb produced by microinjection of picrotoxin (PTX), a GABA antagonist, into the caudoputaminal unit (CPU) was analyzed electrophysiologically. PTX injection resulted in production of sharp, negative field potentials with or without preceding or succeeding positivity in the CPU and cerebral cortex (CX). These spike potentials first appeared in the CPU, thereafter within the CX, and were finally accompanied by dyskinesia indicated by electromyogram activity of the forelimb in association with fully developed CX spike potentials. Dyskinesia disappeared reversibly by cooling, and irreversibly by ablation, of the CX, indicating the crucial participation of the CX in the manifestation of dyskinesia. CPU spike potentials remained even after isolation of the CPU from its major afferents. Grouped discharges of extracellularly recorded single-unit spikes were observed in the CPU in association with the development of CPU spike potentials. Single-unit spikes of the pars reticulata of the substantia nigra were inhibited, and those of the ventromedial nucleus (VM) of the thalamus were excited in association with CPU spike potentials. We therefore propose that the primary origin of the dyskinesia is the CPU and that the inhibitory CPU efferent, as well as the nigrothalamic, pathway plays a basic role in the manifestation of the dyskinesia.

Action Potentials↗
PubMed1990

Interferon-alpha and interferon-beta induce Ia expression in limited protein synthesis condition.

We investigated the regulatory effect of interferons (IFNs) on macrophage (m phi) Ia antigen expression. Unlike type II IFN (IFN-gamma), type I IFNs (IFN-alpha and IFN-beta) were incapable of inducing the accumulation of Ia mRNA. However, when cultured with type I IFN plus cycloheximide (CHX), M phi accumulated significant amounts of Ia-specific mRNA, which was translated into Ia molecules expressed on the cell surface after the removal of CHX. Significant enhancement of Ia mRNA accumulation and the Ia expression were observed also in M phi stimulated with IFN-gamma plus CHX. Type I IFNs suppressed IFN-gamma-dependent Ia expression through the inhibition of Ia mRNA accumulation, but such suppression was not directed to the post-transcriptional step in M phi that had accumulated Ia mRNA in response to stimulation by type I or type II IFN plus CHX. These results seem to indicate that type I IFNs can induce Ia mRNA accumulation but that they also induce some inhibitory protein, the synthesis of which precedes it and is dominant, so that the Ia expression is masked.

Animals↗
PubMed1990

An Escherichia coli protein that preferentially binds to sharply curved DNA.

We attempted to find Escherichia coli proteins which preferentially bind to a curved DNA sequence even in the presence of an excess amount of a non-curved DNA sequence as a competitor, mainly by means of a DNA-binding gel retardation assay. Since the two sequences used had nearly the same nucleotide compositions, including consecutive dA5 stretches, we reasoned that this strategy would allow us to identify proteins which preferentially recognize an overall DNA curvature. We purified such a protein from E. coli. Its preferential binding to the curved DNA was found to be inhibited by distamycin, which removes the curvature from appropriate DNA sequences. The purified protein was identified as the E. coli nucleoid protein, H-NS.

Amino Acid Sequence↗
PubMed1990

Delayed intermolecular gamma-chain cross-linking by factor XIIIa in fibrinogen Asahi characterized by a gamma-Met-310 to Thr substitution with an N-glycosylated gamma-Asn-308.

In an abnormal fibrinogen with gamma-Met-310 to Thr substitution accompanied by an extra oligosaccharide attached to gamma-Asn-308, factor-XIIIa-mediated intermolecular gamma-dimer formation of fibrin was found to be markedly delayed. The delayed gamma-dimer formation was not due to impaired fibrin polymerization because the fibrinogen gamma-chain also failed to be efficiently cross-linked by factor XIIIa. Since fluorescent amine was normally incorporated into the abnormal gamma-chain by factor XIIIa, we conclude that the abnormal molecules were unable to align their gamma-chains in an anti-parallel fashion because of inaccessibility of the molecules with a profoundly perturbed conformation near the carboxyl terminal region of the gamma-chain included in the D domain.

Fibrinogen↗
PubMed1990

[Personal monitoring method for volatile chloroorganic compounds].

A method for measurement of volatile chloroorganic compounds (VCOCs) in air by using porous polymer resin beads, Porapak N was developed as follows: 1. Air was sampled in a glass collection tube packed with Porapak N (1.2 g) at flow rate of 30 ml/min for 24 hours at room temperature. 2. The collection tube was set in a desorption device. The VCOCs adsorbed on the Porapak N were desorbed by heating in a nitrogen flow (180 degrees C, 50 ml/min) and trapped in 10 ml n-hexane cooled by ice. Sufficient recoveries were obtained at desorption time of 8 min. 3. The VCOCs were determined by a gas chromatograph with an electron capture detector (GC-ECD). The present method was applied to determine personal exposure levels for VCOCs. Personal exposure levels of 1,1,1-trichloroethane, carbon tetrachloride, trichloroethylene and tetrachloroethylene were 1.1-6.9, 0.1-0.9, N.D-0.4 and N.D.-4.2 ppb, respectively.

Air↗
PubMed1990

[A new family of Machado-Joseph disease--an abnormal decrease in signal intensity of the putamen in magnetic resonance imaging].

The propositus (case 1) was a 40 year-old man. He had begun to note unsteady walking at age 26. He was found to have cerebellar ataxia and pyramidal signs in addition to minor features such as progressive external ophthalmoplegia, gaze nystagmus, bulging eyes, intention fasciculation-like movements of facial and lingual muscles, and limb dystonia. These findings were categorized into type II form of the disease. One sister (case 3) aged 37 years, and one brother (case 4) aged 44 years of the propositus had also type II form of the disease. His uncle (case 2) had the same cerebellar and extrapyramidal signs accompanied with peripheral nerve signs such as muscle wasting, weakness, hypo-tonus and decreased deep tendon reflexes, and a diagnosis of type III form of the disease was made. In the T2-weighted magnetic resonance imaging (1.5 T, TR 2000 or 3000 msec, TE 120 msec) of the three patients (case 1, 3 and 4), dorsolateral part of the putamen showed decreased signal intensity. Although hypo-intensity of the putamen is often observed in normal elderly people over 50 years old, it is considered to be abnormal when it exists in relatively young people as in this family members.

Adult↗
PubMed1990

A longitudinal study of obesity in Japan: relationship of body habitus between at birth and at age 17.

To clarify the relationship between body habitus from birth to adolescence, changes in weight and height of 309 boys and 335 girls were observed at birth, 3, 6, 11, 14 and 17 years old. Body mass index (BMI = W/H2) was calculated to estimate their habitus at birth, 3 and 17 years, and Rohrer index (W/H3) was used for 6, 11 and 14 years habitus. We define the children in the top decile as obese and those in the bottom decile as lean. Among girls obesity at 17 years old is already related to habitus at birth, while among boys it is related to habitus at 3 years old. Based on these results, we tentatively recommend that prevention of obesity should start as early as possible, at the least from 3 years old.

Adolescent↗
PubMed1989

Macrophage factors which enhance the mixed leukocyte reaction initiated by dendritic cells.

Stimulator cells for the allogeneic MLR are dendritic cells but not macrophages (M phi). M phi, however, enhance the MLR initiated by relatively low doses of dendritic cells. The present report demonstrates that the enhancement of the MLR is mediated by two factors produced by M phi. One is IL-1, inasmuch as it has a Mr approximately 15 kDa, and both partially purified IL-1 and rIL-1 also enhance the MLR. The other has been identified as granulocyte-macrophage (GM)-CSF. It had a Mr approximately 25 kDa, and is reproduced by rGM-CSF. Moreover, the MLR-enhancing activity of both the 25-kDa molecule and rGM-CSF have been neutralized by anti-GM-CSF antiserum. Both IL-1 and GM-CSF have autonomous enhancing activity, but they collaborate with each other in enhancing the MLR. Both factors act on DC to augment their stimulatory activity for allogeneic T lymphocytes.

Adjuvants, Immunologic↗
PubMed1989

Suppression of macrophage Ia antigen expression by endogenous interferon-alpha/beta.

Exogenous interferon-alpha (IFN-alpha) and interferon-beta (IFN-beta) (type I IFNs) are known to suppress the IFN-gamma-dependent expression of class II MHC (Ia) antigens on macrophages (M phi). We report here that the endogenous type I IFNs produced by M phi in response to IFN inducers regulate Ia expression of the M phi themselves. Coculture of M phi with IFN-gamma and polyinosinic-polycytidylic acid [poly(I):poly(C)] resulted in the reduction of Ia expression in comparison with those cultured without poly(I):poly(C). Pretreatment of M phi with poly(I):poly(C) or a bacterial lipopolysaccharide (LPS), which is also a potent IFN inducer, in vitro or in vivo, before being exposed to IFN-gamma was also effective in suppressing the Ia expression. Such suppression was abolished by the addition of anti-IFN-alpha/beta antibodies to the M phi culture along with IFN-gamma. M phi cultured with L-cell conditioned medium (LCM) containing M-CSF were less capable of expressing Ia antigens than those cultured without LCM. The Ia-expressing ability of LCM-treated M phi was also restored by the addition of anti-IFN-alpha/beta antibodies. M phi in the early stage of sterile inflammation were less responsive to IFN-gamma than those in the late stage. These results suggest that endogenous type I IFNs, which are produced in response to natural or synthetic IFN-inducers, regulate M phi Ia expression in an autocrinal manner.

Acute-Phase Reaction↗
PubMed1989

Tumor-specific T cells which form clusters with dendritic cells and tumor cells and deliver macrophage-activating factors.

T cells prepared from tumor (Meth A)-bearing mice were cocultured with homologous tumor cells and splenic dendritic cells to enrich tumor-specific T cells by the separation of clusters. T blasts generated from clusters were capable of inhibiting the in vivo tumor cell growth. The culture supernatant of clustering cells (CLSN) was effective in activating macrophages (M phi) to be cytostatic and cytocidal against tumor cells. Moreover, it was found that CLSN contains at least 3 distinct factors; one was identified as interferon-gamma (IFN-gamma), and the others are so far unidentified, but one acts synergistically with IFN-gamma, possibly as the second signal, and the other cooperates with lipopolysaccharide but not with IFN-gamma. We propose that the tumor-specific T cells secrete soluble mediators which cooperate with each other in M phi activation against tumor cells.

Animals↗
PubMed1989

In vivo effects of recombinant interferon alpha A/D incorporated in gelatin microspheres on murine tumor cell growth.

Intraperitoneal (ip) injections of gelatin microspheres containing a very small amount of recombinant human interferon alpha A/D (A/D-IFN) (IFN-microspheres) plus free A/D-IFN improved the survival of mice bearing ascitic Meth A-R1 cells which we had isolated as IFN-resistant cells under in vitro conditions. The dose of free A/D-IFN in one injection was 10,000 IU, which was insufficient by itself for manifesting in vivo antitumor activity. In these mice, in vivo R1 cell growth was suppressed and macrophage recruitment was enhanced in comparison with mice receiving other control agents. Administration of IFN-microspheres alone was also effective but less than that of IFN-microspheres plus free A/D-IFN. Peritoneal macrophages obtained from normal or R1-bearing mice receiving ip injection of IFN-microspheres with or without free A/D-IFN were activated to inhibit the in vitro growth of R1 cells. The intratumoral injection of IFN-microspheres strongly inhibited the growth of solid R1 tumors. Intravenous injection of IFN-microspheres was effective in preventing the pulmonary metastasis of B16 melanoma cells. These results indicate that the IFN-microsphere is much more effective against tumors than free A/D-IFN.

Animals↗
PubMed1989

Characteristics of lymphocytes appearing in persistent lymphocytosis induced experimentally in cattle by bovine leukemia virus infection.

Properties of peripheral blood lymphocytes (PBL) appearing during persistent lymphocytosis (PL) of cattle that was induced by inoculation of a large number of bovine leukemia virus (BLV)-infected lymphocytes were studied. The PBL possessed surface immunoglobulin at a high ratio and had high syncytium-forming activity. The PBL could not be distinguished from normal PBL cytogenetically. These PBL were shown to be polyclonal cells integrating BLV-proviral DNA randomly into their cellular DNA. These properties were similar to those of PBL appearing at the stage of PL of cattle naturally infected with BLV. The BLV-proviral DNA content of PBL and transcription of viral genes increased in parallel with development of PL and decreased along with a decline of PL indicating the possibility that gene expression and activation of BLV play an important role in induction and maintenance of PL.

Animals↗
PubMed1989

A 595 nanometer band-pass filter enhances the contrast of in situ hybridization signals on chromosome observed after biotin/avidin-alkaline phosphatase localization.

In situ hybridization with DNA probes labeled with biotin and detected by the avidin-alkaline phosphatase/5-bromo-chloroindoxyl phosphate-nitro blue tetrazolium system has been used to localize DNA sequences in chromosomes. To observe the hybridization signals, a phase contrast microscope has often been used because of the good visibility it provides. Use of a 595 nm band pass filter with the phase contrast microscope enhances signal contrast after in situ hybridization without reducing resolution.

Alkaline Phosphatase↗