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Biomedical subjects

M Nakao

Publications and source records attributed to M Nakao.

At least 19 recordsLinked to original sources
PubMed1992

Phosphorylation of chicken oviduct progesterone receptor by cAMP-dependent protein kinase.

Phosphorylation of immunopurified chicken oviduct progesterone receptor (PR) was studied in intact cells and under cell-free conditions. Cytosol PR was isolated by incubation with anti-PR monoclonal antibody alpha PR22 adsorbed to protein A-Sepharose and suspended in a reaction mixture containing 10 mM Mg2+, 0.1 mM [gamma-32P]ATP, and the catalytic subunit of cAMP-dependent protein kinase (cAMP-PK) from bovine heart. All three major proteins of avian PR (PR-A, 79 kDa; PR-B, 110 kDa; 90 kDa) incorporated 32P-radioactivity on serine residues. The phosphorylation reaction was inhibited by synthetic inhibitors of protein kinases, H-8 and 20-residue peptide IP20. A 40 degrees C preexposure of PR oligomer increased phosphorylation of the 90-kDa protein, known to be a heat-shock protein (hsp-90). The extent of the phosphorylation reaction was temperature-dependent as the 32P-incorporation into PR-A and PR-B increased gradually, showing a maximum at 37 degrees C. Multiple phosphopeptides (4-7) were resolved by two-dimensional electrophoresis chromatography following cleavage of 32P-labeled peptides with trypsin. Both A and B forms of receptor showed similar phosphorylation patterns with B receptor digestion exhibiting two to three additional peptides. Under physiological conditions, preincubation of oviduct mince with forskolin, a regulator of intracellular cAMP levels, caused a greater extent of phosphorylation of PR-A and PR-B proteins. The results of this study demonstrate that chicken oviduct PR is an excellent substrate for the action of cAMP-PK in vitro and that this enzyme may be a physiological regulator of progesterone action in the oviduct.

Adenosine Triphosphate↗
PubMed1992

Hepatitis B virus envelope L protein particles. Synthesis and assembly in Saccharomyces cerevisiae, purification and characterization.

The hepatitis B virus envelope gene encodes three transmembrane proteins in frame; S, the product of S gene; M, the product of M (pre-S2 + S) gene; and L, the product of L (pre-S1 + pre-S2 + S) gene. Unlike the S and M proteins, attempts to efficiently synthesize L proteins and assemble them into L protein particles in various eukaryotic cells have been unsuccessful, probably because of the presence of the pre-S1 peptide with an unknown function which appears to be inhibitory to the host secretory apparatus. To investigate the role of the pre-S1 peptide, we constructed an L gene fused with a synthetic gene for chicken-lysozyme signal peptide (C-SIG) at the 5'-terminal and placed the resultant gene under the control of the yeast glyceraldehyde-3-phosphate dehydrogenase gene promoter. After the fused-C-SIG peptide was correctly processed by the yeast secretory apparatus, a yeast transformant synthesized a protein with a molecular mass of approximately 52 kDa at a level of 42% of the total soluble protein. Electron micrographic observation showed that the gene products assembled into 23-nm spherical and filamentous particles. The pre-S peptide of the gene product was deposited into the endoplasmic reticulum (ER) lumen and well-glycosylated. It seemed that the gene products were accumulated as particles in certain specific membrane structures of the yeast secretory apparatus. Moreover, both the amount of mRNAs specific for the L gene and the in vivo stability of the synthesized L proteins did not change significantly by the addition of the C-SIG gene. These findings indicated that, if the pre-S1 peptide penetrates the ER membrane efficiently, the L proteins can be synthesized cotranslationally, translocate across the ER membrane with its S region, and then assemble by themselves into the particle form. Therefore, the pre-S1 peptide may involve weak or reduced signal peptide activity for recognition by the secretory apparatus and/or for the transport of the pre-S peptide into the ER lumen.

Amino Acid Sequence↗
PubMed1992

Conformation of diastereomeric peptide sequences: structural analysis of Z-D-Val-Ac6c-Gly-L-Phe-OMe.

We have recently undertaken a systematic structural analysis of fully protected tetrapeptides containing at the N- and C-terminus either homo- or heterochiral amino acids, spaced by an achiral dipeptide segment. The interest for this class of peptides derives from the observation that, on reverse-phase (HPLC), the homo- and heterochiral sequences have a markedly different retention times. The diastereomeric sequences, namely Z-(L/D)-Val-X-Y-L-Phe-OMe (X = Sar, Gly, Ac3c, Aib, Ac5c, Ac6c, Deg, Dpg, Dbu, Dip, Dph; Y = Sar, Gly, Ac3c, Aib, Ac5c, Ac6c) show different overall hydrophobicity attributed to a different three-dimensional structure that also depends on the X-Y segment. Therefore, following preliminary studies in solution, we report here the detailed x-ray analysis of the tetrapeptide Z-D-Val-Ac6c-Gly-L-Phe-OMe in order to understand the structural features governing the overall hydrophobicity of linear fully protected tetrapeptides.

Amino Acid Sequence↗
PubMed1992

Thermoregulatory responses of young and older men to cold exposure.

Nine young (20-25 years) and ten older (60-71 years) men, matched for body fatness and surface area:mass ratio, underwent cold tests in summer and winter. The cold tests consisted of a 60-min exposure, wearing only swimming trunks, to an air temperature of 17 degrees C (both seasons) and 12 degrees C (winter only). Rectal (Tre) and mean skin (Tsk) temperatures, metabolic heat production (M), systolic (BPs) and diastolic (BPd) blood pressures and heart rate (fc) were measured. During the equilibrium period (28 degrees C air temperature) there were no age-related differences in Tre, Tsk, BPs, BPd, or fc regardless of season, although M of the older men was significantly lower (P < 0.003). The decrease in Tre and Tsk (due to the marked decrease in six of the older men) and the increase in BPs and BPd were significantly greater (P < 0.004) for the older men during all the cold exposures. The rate of increase in M was significantly greater (P < 0.01) for the older group when exposed to 12 degrees C in winter and 17 degrees C in summer (due to the marked increase in four of the older men). This trend was not apparent during the 17 degrees C exposure in winter. There was no age-related difference in fc during the exposures. Significant decreases in Tre and Tsk and increases in M, BPs and BPd during the 12 degrees C exposure were observed for the older group (P < 0.003) compared to their responses during the 17 degrees C exposure in winter. In contrast, Tre, M, BPs in the young group were not affected as much by the colder environment. It was concluded that older men have more variable responses and some appear more or less responsive to mild and moderate cold air than young men.

Adipose Tissue↗
PubMed1992

Naturally occurring immunoglobulin M antibodies: enhancement of phagocytic and microbicidal activities of human neutrophils against Toxoplasma gondii.

Naturally occurring immunoglobulin M antibodies to Toxoplasma gondii in human sera were examined for their ability to enhance toxoplasmacidal activities of human neutrophils to show a role of natural antibodies in immunity to the early stage of Toxoplasma infection in humans. Neutrophils were mixed with tachyzoites at a ratio of 1:5 in the presence or absence of antibodies and were cultured for 1-18 h for microscopical examination. The count of tachyzoites phagocytosed in 200 neutrophils within 1 h was significantly higher in the presence of sera with natural IgM antibody levels of greater than 0.8 than those of less than 0.1, with 2.4- to 2.9-fold differences (P less than 0.02). The total tachyzoite counts at 18 h decreased to 26-39% of those at 1 h in the presence of natural IgM antibody levels of greater than 0.8 (P less than 0.01), while the counts at 1 h consistently increased by 18 h in the absence of natural IgM antibodies. These results indicate that relatively high levels of natural IgM antibodies enhanced phagocytic and microbicidal activities of neutrophils against Toxoplasma. The enhancement was dose dependent, and was also weaker than that obtained with the same dilution of sera from individuals with chronic or acute infections. Live and dead tachyzoite counts in infected neutrophils suggested a quicker effect of natural IgM antibodies than IgG antibodies elicited by infection.

Animals↗
PubMed1992

Antibacterial properties of SCE-2787, a new cephem antibiotic.

The in-vitro antibacterial properties of SCE-2787, a new semi-synthetic parenteral cephalosporin, were evaluated by comparing its affinities for penicillin-binding proteins (PBPs), its bactericidal activity and its effects on morphology with those of ceftazidime, cefpirome and E-1040. SCE-2787 and cefpirome had higher affinities for PBPs 1 and 2 of Staphylococcus aureus, and a more potent anti-staphylococcal activity, than ceftazidime and E-1040. All four antibiotics had similar activity against Escherichia coli, and showed similar affinities for PBP 3 of this organism. SCE-2787, ceftazidime and E-1040 were more potent than cefpirome against Pseudomonas aeruginosa, and showed higher affinities for the P. aeruginosa PBP 3. The wide-spectrum antibacterial activity of SCE-2787 can be explained, in general, by its high affinities for PBPs, SCE-2787, at half its MIC level or higher, was bactericidal against all the bacterial strains examined, as were the other antibiotics tested. Exposure of S. aureus to SCE-2787 resulted in the formation of cell walls with irregular septa which subsequently thickened and collapsed. Elongation was the major morphological change of E. coli and P. aeruginosa cells treated with SCE-2787. E. coli cells were converted to 'ghosts', infrequent in P. aeruginosa, after prolonged incubation with higher concentrations of SCE-2787.

Anti-Bacterial Agents↗
PubMed1992

Prevalence of Lyme borreliosis spirochetes in ixodid ticks of Japan, with special reference to a new potential vector, Ixodes ovatus (Acari: Ixodidae).

To determine the vectors of Lyme borreliosis in Japan, the ixodid ticks taken in Hokkaido, Fukushima, Nagano, Ehime, and Kochi Prefectures were examined individually for spirochetal infections by culturing their midgut tissues in BSK medium. The cultivable spirochetes identified as Borrelia burgdorferi were detected in Ixodes persulcatus Schulze adults (15.5% of 634), nymph (6.7% of 15) and Ixodes ovatus Neumann adult (9.6% of 188) from Hokkaido, I. ovatus adults (25.5% of 47) from Fukushima, and I. persulcatus adults (21.7% of 143) and I. ovatus adults (27.1% of 85) from Nagano. However, 72 Haemaphysalis spp. from Ehime and Kochi were free from spirochetal infection. I. persulcatus is a vector of Lyme borreliosis in the Far East, but in Japan, I. ovatus may also transmit the spirochetes to human and feral animals.

Animals↗
PubMed1992

Comparison of Borrelia burgdorferi isolated from humans and ixodid ticks in Hokkaido, Japan.

Four spirochetal isolates (JEM1 to JEM4) were obtained from cutaneous lesions of patients manifesting erythema chronicum migrans in Hokkaido, Japan. In the protein profiles by SDS-PAGE and the reactivities with monoclonal antibodies (H5332 and H9724) by immunoblotting, all the human isolates were identical with the tick isolates from Ixodes persulcatus. These data indicate that I. persulcatus is an important vector of Lyme disease for humans in Japan.

Animals↗
PubMed1992

[Study of the anti Borrelia burgdorferi antibody of hunters in Hokkaido].

We examined the sera of 587 hunters in Hokkaido (Japan's northernmost island) for the antibody to Borrelia burgdorferi (B. burgdorferi) by enzyme immunoassay, clarified the conditions related to antibody positivity in these subjects according to region, and studied the effects of factors such as age and lifestyle on the antibody titer. In contrast with an anti-B. burgdorferi antibody positive rate of 7.1% in control sera, that in the hunters' sera was 16.0%. Among those positive for the anti-B. burgdorferi antibody, the antibody positive rate in sera excluding those testing positive in the serological test for syphilis was 5.5% in the controls, and 15.4% in the hunters, the latter rate being significantly higher (p less than 0.05). In both hunters and control groups, the antibody-positive rate tended to be higher in older subjects, but the antibody titer showed no correlation with their age, or the duration of their hunting experience. Examination of the hunters' occupations revealed a tendency toward high titers in those engaged in dairy farming. The antibody positivity of those who went gathering edible wild plants was significantly higher than those did not (p less than 0.05). These observations suggested that the high antibody-positive rate in hunters may have been due largely to the effect of activities other than hunting as sources of infection by Borrelia.

Adult↗
PubMed1992

Questionnaire surveys of cases of tick bite and Lyme borreliosis in hunters in Hokkaido with reference to detection of anti-Borrelia burgdorferi antibody.

An epidemic of Lyme borreliosis on Hokkaido island, Japan, was surveyed by questionnaire in 587 hunters. The 308 returns (52.4%) revealed episodes of tick bite (usually 2 or more) in 210 cases. Skin rashes appeared in 164 cases. Associated itching, pain, etc., but not skin rash, were more frequent after 2 or more tick bite. Previous determinations of anti-Borrelia burgdorferi antibody titers in these subjects and in controls suggested an association with outdoor activities other than hunting, and among 33 cases of dermatological symptoms and 23 of articular symptoms, 4 and 2, respectively, were antibody-positive. Most of these antibody-positive subjects had suffered tick bite at least twice, but had had no antibiotic treatment. Three subjects with joint disorders were antibody-positive. These findings suggested that the many hunters exposed to Borrelia burgdorferi frequently carried latent infections, and that some had latent form of arthritis, dermatitis and other disorders.

Adult↗
PubMed1992

Comparison between natural and immunized anti-GM1 antibodies analyzed by marker releasing rate assay with liposome.

Naturally occurring rabbit anti-GM1 was compared with immunized induced anti-GM1 antibody in the same individual rabbits by the characterization of immune potency determined by complement-dependent damage to liposomes containing GM1 as antigen. Antigen-antibody reaction was the rate determining step in this assay. The maximum rate was measured by the first derivative conversion monitoring in spectrophotometry and the maximum level of marker released was measured by the conventional method described previously. When the concentration of sera required to get fifty percent of maximum values in each assay were compared, the ratios (rate assay/conventional assay) were 5.7 to 10.0 in natural antibodies and 3.2 to 2.3 in immunized induced antibodies, respectively. Furthermore, the maximum rate of marker release from liposome was not correlated with the maximum level of marker released depended on the sources of antibodies. These results suggest that natural antibody, even the titer was high in conventional liposome assay, has different characteristics compared with the immunized induced antibody.

Animals↗
PubMed1992

Nucleotide sequence of the third cytokine LD78 gene and mapping of all three LD78 gene loci to human chromosome 17.

Cytokine LD78 is a member of a newly identified cytokine superfamily. We cloned the third human gene for the LD78, termed LD78 gamma and the sequence analysis showed that it is a 5'-truncated pseudogene. Exons 2 and 3 and the intron between them are highly homologous to those of the LD78 beta gene, hence, the gamma gene was probably derived from the beta gene. Southern blot analysis of human x mouse somatic hybrid cell DNAs and in situ hybridization experiments mapped all the three gene loci on human chromosome 17q21.1-q21.3. Analysis of DNAs from family members supports our previous finding that the beta and gamma genes on each of the paired chromosome 17 vary in copy number and that the LD78 alpha gene is presumably a single copy. In our analyses of cosmid clones, the LD78 beta gene and the second gene for AT744, which is also a member of the superfamily are closely linked in a head-to-head arrangement. The mechanism of generation of the three LD78 genes is discussed.

Base Sequence↗
PubMed1992

Characterization of Borrelia burgdorferi isolated from Ixodes persulcatus and Ixodes ovatus ticks in Japan.

The Lyme disease spirochete Borrelia burgdorferi was detected in the adult stage of the ixodid ticks Ixodes persulcatus and I. ovatus collected in various localities in Japan. The total prevalence values were 16.6% of 777 I. persulcatus and 23.6% of 687 I. ovatus. Sixty-two (63.9%) of 97 isolates from I. persulcatus contained the 30-34-kD heterogeneous outer surface protein A (OspA) that reacted with monoclonal antibody H5332. In contrast, all 128 isolates from I. ovatus were homogeneous with regard to the type of 30-kD OspA protein, and were different from the I. persulcatus isolates in their protein composition. These data suggest that the transmission cycle of B. burgdorferi in I. ovatus is not related to that in I. persulcatus. No cases of Lyme disease transmitted by I. ovatus have been confirmed in Japan, in spite of the abundance of human tick bites by this species. Accordingly, the spirochetes of I. ovatus are thought to be a variant of B. burgdorferi with low virulence.

Animals↗
PubMed1992

Charge movements via the cardiac Na,K-ATPase.

The voltage dependence of transient and steady-state pump currents was examined in guinea pig ventricular myocytes to investigate mechanisms of charge translocation by the Na,K-ATPase. Na/K pump current was determined at approximately 36 degrees C as strophanthidin-sensitive whole-cell current in myocytes voltage clamped and internally dialyzed via wide tipped pipettes containing a pipette perfusion device. External Na ions diminished stationary pump current during forward Na/K cycling in a voltage dependent manner, the inhibition becoming stronger upon hyperpolarization. When Na,K-ATPase activity was restricted to Na translocation steps, stationary pump current was prevented but voltage pulses still elicited large transient pump currents which could be abolished by oligomycin B (> or = 2 micrograms/ml). The transients arose instantaneously on stepping the voltage, and decayed with voltage-dependent approximately single exponential time courses. The decay rates, and their high temperature sensitivity (approximately 200 s-1 at 0 mV at 36 degrees C; approximately 40 s-1 at 20 degrees C), suggest that the charge movements were limited by a conformational change associated with Na deocclusion. Those rates varied asymmetrically with voltage, changing little at positive voltages but increasing roughly exponentially with hyperpolarization (e-fold/approximately 80 mV). Lowering the extracellular [Na] ([Na]o) slowed the relaxation of charge movement at negative potentials but had little effect at positive potentials, and so shifted the rate constant-voltage curve to the left. The implied dependence on [Na]o of the backward rate constant governing pump charge movement accounts satisfactorily for the observed [Na]o sensitivity of stationary outward Na/K pump current, and indicates that the voltage-dependent step somehow involves the release of Na ions to the external medium. However, no strophanthidin-sensitive current was seen, at saturating external [K], when Na,K-ATPase activity was limited to K translocation steps by complete withdrawal of Na ions. But, at very low [Na]o, a weak negative slope appeared in the stationary pump current-voltage relationship at subsaturating, but not at saturating, external [K], indicating an increased apparent affinity for external K at more negative potentials. The results support the existence of a high field access channel through which extracellular Na and K ions must pass before interacting with their binding sites deep within the Na,K-ATPase molecule.

Adenosine Triphosphate↗
PubMed1992

[Development of automated lactate analyzer with continuous blood sampling for monitoring blood lactate and its application for the testing of physical exercise].

The anaerobic threshold is useful for estimating the intensity of physical exercise. It is shown as either an increase in blood concentrations of lactate or a disproportionate increase in ventilation. We developed a lactate analyzer based on an electroenzymatic method with a continuous blood sampling system through a double-lumen catheter. Ascorbic acid, bilirubin, hemoglobin, creatinine, uric acid, and glucose did not interfere the results. The lactate concentrations in blood samples from healthy subjects during physical exercise correlated well (r = 0.993) with results measured by the conventional enzymatic method. We measured the concentrations of blood lactate with a use of this lactate analyzer to see the anaerobic threshold in nine healthy volunteers during exercise on a treadmill with an increasing workload. The point at which lactate concentrations started to increase was detected easily. The anaerobic threshold identified as a disproportionate increase in ventilation was seen at almost the same time. We conclude that the lactate analyzer, with a continuous blood sampling system, can measure precisely concentrations of lactate in blood and can detect the anaerobic threshold during physical exercise.

Adult↗
PubMed1992

[A program for continuous infusion of cardiovascular agents (CIRCULATION)--how to derive the algorithm and how to use the mathematical formula in this program].

Recently, many cardiovascular agents came to be administered to serious or perioperative cases continuously, and difficult calculation became necessary. For continuous infusion of cardiovascular agents, we devised a personal computer program (CIRCULATION) to avoid difficult calculation for PC-9801 series (NEC) by a C language (Turbo-C, Version 2.0). It is easy to use the program, and it calculates the algorithm for many cardiovascular agents in a second. The program is very useful for anesthesiologists and for other doctors when they administer various cardiovascular agents.

Algorithms↗
PubMed1992

[Neo-adjuvant chemotherapy with cisplatin, 5-fluorouracil, vindesine in head and neck cancer].

Neo-adjuvant chemotherapy with CDDP combination was introduced into the treatment of advanced head and neck cancer. Twenty-three patients with s.c.c of head and neck were given combination chemotherapy consisting of CDDP, VDS and 5-FU before surgical treatment in our department. CR and PR of this trial in all patients were 4 and 35%, respectively. The WBC nadir occurred around 2 weeks later, but all the patients recovered prior to the next cycle or surgical treatment. Renal dysfunction, nausea, vomiting and depilation were generally mild. VDS is useful as one of the neo-adjuvant drugs for the treatment of head and neck cancer. Long-term observation in connection with this treatment is required.

Antineoplastic Combined Chemotherapy Protocols↗