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Biomedical subjects

N Okamura

Publications and source records attributed to N Okamura.

At least 91 records · Page 5Linked to original sources
PubMed1996

Differences in mechanisms for cell-free NADPH oxidase activation between arachidonate and sodium dodecyl sulfate.

Mechanisms for the cell-free activation of NADPH oxidase by sodium dodecyl sulfate (SDS) and arachidonate were compared in relation to their responsiveness to short chain diacylglycerols. The plasma membrane and cytosol prepared from guinea pig neutrophils were used for the cell-free system. The activation of NADPH oxidase by SDS was enhanced about 5- to 10-fold by 1,2-dioctanoylglycerol (diC8), but not by either 1,2-dihexanoylglycerol (diC6) or 1,2-didecanoylglycerol (diC10). However, none of these diacylglycerols potentiated the NADPH oxidase activation by arachidonate. The maximal extent of activation by the combination of SDS and diC8 was similar to that by arachidonate alone. In the presence of sufficient amounts of diC8 and SDS, GTP gamma S potentiated the activation of NADPH oxidase. The potentiating activity of diC8 was preserved in the membrane fraction, not in the cytosol fraction. These results suggest that arachidonate may possess the functions of both SDS and diC8 in the activation. In addition, diC8 and GTP gamma S seem to independently enhance the NADPH oxidase activation.

Animals↗
PubMed1996

Development of photosynthesis and respiration measurement system using mass spectrometry.

A closed gas-exchange system was developed to measure gross photosynthesis and respiration discriminately and simultaneously. The system developed in this study included a high performance mass spectral analyzer for gas measurements. The gas-exchange system consisted of a 3L assimilation leaf chamber, a 1L flexible metallic bag, gas supply apparatus, and a lighting system. The lights were turned on and gas measurements were started after the initial 12CO2 concentration level was increased to 500 ppm. The 13CO2 gas was added to the chamber 10 min after the start of the light period. The lights were turned off 15 min after the addition of 13CO2. The 12CO2 and 13CO2 concentrations in the chamber during the light and dark periods were measured for pothos and maize leaves. The 13CO2 absorption rate by the leaves was larger than that for 12CO2 during the light period. It was assumed that the 13CO2 absorbed by photosynthesis was not evoluted by respiration during the first 25 min from the start of the light period. Based on this assumption, gross photosynthetic rate and respiration rate were estimated by calculating the difference in uptake rates of 12CO2 and 13CO2 during the light period.

Argon↗
PubMed1996

[Experimental studies on the cell adhesion molecule E-cadherin and in vitro invasion of endometrial carcinoma cell lines].

The enhancement of the in vitro invasive ability and the morphological changes caused by anti-E-cadherin antibody HECD-1 were investigated by in vitro invasion assay and electron microscopy in three human endometrial carcinoma cell lines. The cell lines were NUE-1 (E-cadherin negative and high in vitro invasive ability), HEC-1BE and HEC-108 (E-cadherin positive and low in vitro invasive ability). In NUE-1 invasive ability was not enhanced by HECD-1, but in HEC-1BE and HEC-108 invasive ability was enhanced to 223 +/- 41.2% and 307 +/- 173% by 5 micrograms/ml HECD-1. Morphologically NUE-1 invaded the extracellular matrix (Matrigel) with a long micro villis. But in HEC-1BE and HEC-108 the villis did not invade the Matrigel, the whole cell invaded it. Together with HECD-1, HEC-1BE and HEC-108 were changed to become similar to the NUE-1 cell line with high invasive ability and the micro villis invaded the Matrigel.

Adenocarcinoma↗
PubMed1995

Respiratory burst and tyrosine phosphorylation by vanadate.

We studied involvement of tyrosine-phosphorylated proteins in activation of NADPH oxidase in guinea pig neutrophils. Pervanadate, which is the oxidized form of orthovanadate, induced O2- production and protein tyrosine phosphorylation in neutrophils. O2- production induced by pervanadate was more sensitive to the tyrosine kinase-specific inhibitor, ST-638, as compared with the production induced by PMA. On the other hand, staurosporine more selectively inhibited PMA-induced O2- production than pervanadate-induced production. These results indicate that tyrosine kinase, not protein kinase C, is involved in pervanadate-induced O2- production. The tyrosine-phosphorylated proteins were detected in both the cytosol and membrane fractions prepared from pervanadate-induced neutrophils. In order to examine if tyrosine residues of some components of NADPH oxidase were directly phosphorylated, tyrosine-phosphorylated proteins were removed from solubilized membranes prepared from the pervanadate-stimulated neutrophils by immunoprecipitation with an anti-phosphotyrosine anti-body. NADPH oxidase activity in the solubilized membranes was not decreased by the treatment. These findings suggest that the components of NADPH oxidase are not tyrosine-phosphorylated by pervanadate treatment, that tyrosine phosphorylation may be involved in the signal transduction pathway of NADPH oxidase activation by pervanadate, and that this pathway is independent of the activation by protein kinase C.

Alkaloids↗
PubMed1995

Hyperphosphorylated p47-phox lost the ability to activate NADPH oxidase in guinea pig neutrophils.

p47-phox is one of the cytosolic activation factors of NADPH oxidase in neutrophils and known to translocate to plasma membranes and function by protein kinase C-phosphorylation. In cytosol fraction, prepared from calyculin A-treated neutrophils, the activity of cytosolic factor to activate NADPH oxidase was more reduced than that from PMA-treated cells. But, p47-phox did not translocate to the membranes, even if p47-phox was hyperphosphorylated in the calyculin A-treated neutrophils. Such hyperphosphorylated p47-phox seemed to lose the activity to constitute NADPH oxidase complex.

Animals↗
PubMed1995

Direct evidence for the elevated synthesis and secretion of procathepsin L in the distal caput epididymis of boar.

The proteins which are secreted from the restricted part of the epididymis are suggested to sustain sperm maturation. In porcine species, as the potential abilities of sperm for movement and fertilization greatly increase in the corpus epididymis, the secretions in both the caput and corpus epididymis seem to be very important for the sperm maturation. In this study, we have directed our attention to the 40 kDa protein which is detected in the fluid of the distal caput epididymis of boar. It was purified from the porcine cauda epididymal fluid and its cDNA was cloned from the cDNA library of the distal caput epididymis. According to the deduced amino acid sequence, the 40 kDa protein has been identified as procathepsin L. Northern blot analysis showed that the procathepsin L mRNA was most abundant in the distal caput epididymis among the tissues as examined. Consistent with the distribution of the procathepsin L mRNA in the epididymis, the activity of procathepsin L was absent in the fluid of the proximal and mid caput epididymis and first appeared in the distal caput epididymal fluid, whose contents gradually decreased with the passage through the epididymis. These results first appeared in the first distal caput epididymis expresses very high levels of procathepsin L and unusually secretes it into the luminal fluid instead of targeting it to lysosomes. It has been also found that the mRNA of PDGF, which is known to enhance cathepsin L expression in the culture cells, is very high in the mid caput epididymis, which just precedes the site of procathepsin L secretion. This result indicates that PDGF directly regulates the locally restricted expression and secretion of procathepsin L in the epididymis, which is one of the possible mechanisms involved in the functional differentiation in the epididymis.

Amino Acid Sequence↗
PubMed1995

High incidence of point mutation in K-ras codon 12 in carcinoma of the fallopian tube.

BACKGROUND: Adenocarcinoma of the fallopian tube is a rare tumor with a poor prognosis. Whether these carcinomas possess any genetic changes that contribute to their malignant behavior is unknown and to date few studies regarding the molecular pathogenesis of these tumors have been reported. In adenocarcinoma of the endometrium, mutations in the first exon of K-ras, although relatively infrequent, were observed to be an independent risk factor for poor clinical outcome. METHODS: Eight patients with adenocarcinoma of the fallopian tube were examined for mutations in the 12th codon of K-ras. DNA was obtained from single sections of paraffin embedded tumor tissue and the first exon of K-ras was amplified by the polymerase chain reaction. Point mutations were assayed using a nonradioactive restriction fragment length polymorphism technique. RESULTS: The eight patients in this study varied in clinical stage from I-IV and were all treated with surgery and chemotherapy. Six of eight of the patients died and one of the surviving patients had metastases in the vertebrae. K-ras point mutations were detected at codon 12 in seven of the eight tumors (87.5%). CONCLUSIONS: K-ras mutations occurred with high frequency in this series of eight patients with fallopian tube carcinoma, suggesting that mutations of this protooncogene could play an important role in the molecular pathogenesis of this lesion.

Adenocarcinoma↗
PubMed1995

Cloning of complementary DNA encoding a 135-kilodalton protein secreted from porcine corpus epididymis and its identification as an epididymis-specific alpha-mannosidase.

In the preceding study (Okamura et al., 1992; Biol Reprod 47:1040-1052) we suggested that a 135-kDa protein secreted by porcine epididymis is involved in the sperm maturation. In this work, we have isolated the cDNA clone coding the 135-kDa protein in an effort to investigate its structure and function. The 135-kDa protein was purified from porcine cauda epididymal fluid. Three oligonucleotide probes were synthesized according to the amino acid sequences of N-termini of the native protein and trypsin-digested peptides. A cDNA clone hybridizing with these three probes was isolated from the cDNA library derived from the porcine proximal corpus epididymis. It encodes a novel protein with 1,006 amino acid residues in an open reading frame. Its overall amino acid sequence was significantly homologous (25.7%) to the alpha-mannosidase precursor of Dictiostelium discoideum (P34098). The 135-kDa protein could digest both p-nitro-phenyl-alpha-D-mannoside and high mannose oligo saccharide (Man8-GlcNAc2), strongly suggesting that it is an alpha-mannosidase homologue. The expression of this protein was specific to porcine and was localized to the very narrow parts of epididymis: the border of the caput and corpus epididymis. This protein may serve as a good marker for the functional differentiation in porcine epididymis. A possible role of this protein in the species-specific sperm-egg interaction is discussed.

Amino Acid Sequence↗
PubMed1995

Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalis.

Four diterpenoids, carnosic acid (1), carnosol (2), rosmanol (3), and epirosmanol (4), were isolated as antioxidative agents from the leaves of Rosmarinus officinalis by bioassay-directed fractionation. These diterpenoids inhibited superoxide anion production in the xanthine/xanthine oxidase system. Mitochondrial and microsomal lipid peroxidation induced by NADH or NADPH oxidation were also completely inhibited by these diterpenes at the concentration of 3-30 microM. Furthermore, carnosic acid protected red cells against oxidative hemolysis. These phenolic diterpenes were shown to be effective to protect biological systems against oxidative stresses.

Diterpenes↗
PubMed1995

Bisalbumin (fast and slow type) induced by human pancreatic juice.

To clarify the relationship of pancreatic juice to bisalbumin, we examined the effects of human pancreatic juice and pancreatic proteolytic enzymes on human serum albumin. Electrophoresis showed that a fast-moving band and an increased component of alpha 1-globulin appeared after incubation of serum with pancreatic juice. These components were shown to be albumins by immunofixation and immunoelectrophoresis. The alpha 1-component increased after incubation of serum with trypsin, and was confirmed as a slow-type albumin by immunoelectrophoresis. Fast-type albumin was observed after incubation of serum with chymotrypsin, and carboxypeptidases A and B. In all patients with pancreatic ascites, the fast- and slow-type albumins were seen in serum and ascitic fluid. Bisalbumins appeared in ascites at higher concentrations than in serum, and disappeared after surgical or conservative treatment. The results demonstrate that human pancreatic juice can produce fast- and slow-type albumins by proteolytic enzymes, and they are seen in patients with pancreatic ascites.

Albumins↗
PubMed1995

Fatty acyl-Co A: sphingosine acyltransferase in bovine brain mitochondria: its solubilization and reconstitution onto the membrane lipid liposomes.

Fatty acyl-Co A: sphingosine acyltransferase (ceramide synthase, EC 2.3.1.24) is mainly localized in the microsomal and mitochondrial membranes. Attempts to isolate the enzyme have failed, largely because there has been little or no detection of the enzyme activity in detergent extracts. In this study, we solubilized the membrane-bound enzyme from bovine brain mitochondria with a Tris-HCl buffer containing 2% Triton X-100 and, after removal of the detergent, reconstituted it with the membrane lipid liposomes. The specific activity of the reconstituted enzyme was approx. 8 times higher than that of the solubilized enzyme. We next examined the lipid dependence of the enzyme, using various phospholipid liposomes. The ability of phospholipids to enhance the activity of solubilized ceramide synthase was specific and structure-related. The most potent stimulator was phosphatidylserine liposomes, suggesting an important role of the net negative charges. This paper also describes a highly reproducible high-performance liquid chromatographic (HPLC) procedure for the determination of ceramide synthase activity. Combination of the HPLC method with the reconstituted enzyme system appears to be suitable for elucidating the characteristics of this enzyme.

Acyltransferases↗
PubMed1995

[A study on the effects of physical load on high school baseball players during midsummer games].

This study attempted to measure the physical load on high school baseball players during games played under extremely hot and humid conditions in the summer. The factors used to determine physical load were the following: body weight, oral temperature, blood pressure, heart rate, and serum biochemical elements. These were measured before and after the game. One hundred twenty-six baseball players from 7 high schools participated in this study. All the games were played under conditions of high temperature 34 degrees Celsius dry-bulb, 26 degrees Celsius wet-bulb, 41 degrees Celsius black-globe, 30 degrees WBGT, which are likely to cause heat-related illnesses. The results were as follows. 1) The physical load of baseball players during the game showed a 1.8 percent decrease in average body weight due to perspiration, a 0.35 degrees C increase in oral temperature and an increase in the heart rate. Examination of the serum biochemical elements showed that muscle deviation ferment changed due to muscular activity and blood condensed due to perspiration. The physical load levels of baseball players were influenced more by extreme heat than by exercise during the game. 2) The group of starting players showed higher body weight loss, oral temperature, heart rate, blood condensation and muscle deviation ferment levels than the group of players on the bench due to the difference in the length of exposure to summer heat and the amount of physical exertion. The changes in physical load levels during the game for the group of starting players were greater than those for the group for players on the bench. 3) Considering the changes in body weight, blood condensation and muscle deviation ferment, we can say that physical loads of players differed according to their positions, the pitcher having the greatest load, followed in descending order by the catcher, infielders, and outfielders. It has been recommended that high school baseball players should take different kinds of rest depending on their positions in order to recover from fatigue as soon as possible after a game.

Adolescent↗
PubMed1995

[Is CA125 useful in the management of recurrence of endometrial carcinoma?].

It has been considered that there is no useful serum tumor marker to diagnose endometrial cancer. But recently several reports describe how the serum CA125 value decreases in patients who have received bilateral oophorectomy and in postmenopausal women. In this study, we therefore determined a new cutoff level for serum CA125 and examined the usefulness of serum CA125 in the assessment of recurrence in 42 endometrial cancer cases. These cases were divided into 3 groups: one of 22 low risk cases, 10 moderate risk cases and 10 high risk cases cased by prognosis 1) In the low risk group, 5 cases had a higher serum CA125 level within 1 month after operation than before. 2) In 151 measurements, the mean CA125 value was 9.7 +/- 3.6U/ml, so we considered that 17 U/ml is the cutoff value for determining recurrence. 3) In the low risk group, the CA125 value was either lower than 17U/ml or it has not continued to increase. 4) We divided the high risk group into 3 subgroups into those who had died within 6 months, those who died within 13-14 months and those who died 2-5 years after the initial treatment. In the group who died 13-14 months after the initial treatment, the seurm CA125 level had continued to be high and there was no change in the value after the initial treatment. In the group who died 2-5 years after the initial treatment, the mean +/- S.D. for serum CA125 was 157.3 +/- 158.3U/ml, the maximum was 377U/ml and the minimum was 28U/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1995

The effect of DU-6859a, a new potent fluoroquinolone, on fecal microflora in human volunteers.

Following the oral administration of DU-6859a to six healthy male volunteers at 100 mg per dose three times a day for seven consecutive days, the degree of disturbances of fecal microflora and fecal drug concentrations were examined. The total viable count decreased transiently during the administration due to changes in the number of members of the family Bacteroidaceae, the most predominant organisms. The other obligate anaerobes and most aerobes including facultative anaerobes were suppressed markedly by DU-6859a, with an exception of yeasts. Members of the family Enterobacteriaceae and most of anaerobic bacteria were reduced to below the detection limit in all subjects from the 3rd day of administration period to one day after the discontinuation of the drug. Clostridium difficile was detected in one of the volunteers at the end of administration. Side effects, such as mild transient soft stool and mild transient diarrhoea, were observed in five and one volunteers, respectively. During the administration, DU-6859a was detected in feces at high concentrations which correlated well with the decrease of susceptible members of fecal flora as well as their detection rate.

Adult↗
PubMed1994

Activation mechanism of NADPH oxidase by SDS in intact guinea pig neutrophils.

It is well known that sodium dodecyl sulfate (SDS) activates NADPH oxidase in a cell-free system independently of protein kinase C (PKC). However, in intact neutrophils, direct evidence has never been presented to show that O2- production by SDS is actually due to the NADPH oxidase activation observed in the cell-free system. So, in this paper, we investigated the activation mechanism by SDS in intact guinea pig neutrophils. We previously reported that hypotonic treatment reversibly enhanced O2- production stimulated by PKC activators in intact neutrophils (M. Hiura et al., 1991, Arch. Biochem. Biophys. 291, 31-37). In this paper, SDS also significantly stimulated O2- production in the intact cells under the hypotonic condition. This enhancement was gradual and was PKC inhibitor resistant. Furthermore, phosphorylation of the 46-kDa protein, one of cytosolic activation factors, was not detected by autoradiography of two-dimensional electrophoresis. Translocation of cytosolic activation factors was demonstrated by a decrease in the activity of the factors remained in the cytosol. In the presence of SDS, addition of 1-oleoyl-2-acetylglycerol, a PKC activator, further enhanced O2- production and translocation of the cytosolic activation factors. On the other hand, SDS remarkably increased membrane fluidity in intact neutrophils as well as in the cell-free system. These results indicate that activation of NADPH oxidase by SDS in intact neutrophils seems to be partly due to the same mechanism observed in cell-free activation, and that SDS alone slightly activates the oxidase and other stimulation, such as hypotonic and/or PKC activator treatments, is required for significant activation. The increase in the membrane fluidity may be one of the activation mechanisms of NADPH oxidase by SDS.

Animals↗
PubMed1994

Flavonoids in Rosmarinus officinalis leaves.

Three new flavonoid glucuronides, luteolin 3'-O-beta-D-glucuronide, luteolin 3'-O-(4"-O-acetyl)-beta-D-glucuronide, and luteolin 3'-O-(3"-O-acetyl)-beta-D-glucuronide, together with hesperidin, were isolated from 50% aqueous MeOH extract of the leaves of rosemary. The structures were established by chemical and spectroscopic methods. Their antioxidant activities were evaluated by a ferric thiocyanate method with hesperidin showing the greatest activity.

Antioxidants↗