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Biomedical subjects

Y Sagara

Publications and source records attributed to Y Sagara.

At least 127 records · Page 7Linked to original sources
PubMed1995

A new computer network system for communicating perinatal decision support information via a telephone line.

OBJECTIVE: For fetal monitoring and assessment of high risk mother and fetus at regional hospitals, we developed a new computer network system. METHODS: The system incorporates a notebook-type personal computer (PC-9801nv) at regional hospital for communication in with 3 servers (IBM5580-YOC) connected via 2 Ethernet LANs to 2 host computers (IBM3080, IBM3174) and 5 workstations (IBM5521 V2b), and transmits the compressed data by telephone. When the data arrive, the doctor in perinatal center can immediately display and interpret the data on his workstation and give appropriate advice to the doctor at the regional hospital. RESULTS: The rate of reliable data transmission was 100%. Each 1 hour recording session and characteristic perinatal information was transmitted in less than 2 minutes. Regional medical institutions can easily access the center, and thereby can receive both simplified automatic diagnosis by fetal cardiotocography and pregnancy-risk evaluation. CONCLUSIONS: Because this system uses telephone circuits, it can be accessed from all regions of the country. Thus, our system is useful for perinatal management of high risk mother and fetus.

Adult↗
PubMed1995

Additional evidence for blepharismin photoreceptor pigment mediating step-up photophobic response of unicellular organism, Blepharisma.

In the ciliated protozoan, Blepharisma japonicum, the pink-colored pigment (blepharismin) contained in the pigment granules is believed to be the photoreceptor pigment responsible for the step-up photophobic response. When the cells partially bleached by extrusion of the pigment granules caused by cold shock were subsequently cultured under illuminated conditions, the pigment-less granules regenerated and the cells were further bleached (pigment content below 0.5%). The photosensitivity of such colorless cells disappeared completely. In contrast, the blepharismin pigment regenerated gradually when such colorless cells were transferred to darkness. The photosensitivity of the cells also recovered with regeneration of the pigment. We found that blepharismin pigment was not photobleached in the absence of O2. The step-up photophobic response was also completely repressed in the absence of O2. These results strongly confirm that blepharismin is a photoreceptor pigment mediating photobehavior of Blepharisma and that O2 is required for the early step in the phototransduction of the light-excited pigment.

Animals↗
PubMed1995

Purification and characterization of a cam repressor (CamR) for the cytochrome P-450cam hydroxylase operon on the Pseudomonas putida CAM plasmid.

The cytochrome P-450cam hydroxylase operon of Pseudomonas putida PpG1 (ATCC 17543) encodes proteins responsible for early steps of the degradation of D-camphor. Transcription of this operon is negatively controlled by the cam repressor (CamR), and the expression of camR is autoregulated. CamR was purified from Escherichia coli harboring an overproducing plasmid. The repressor forms a homodimer with a molecular mass of 40 kDa, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and gel filtration. CamR protected a specific DNA region from attack by DNase I. This region contains a palindromic operator of the cytochrome P-450cam hydroxylase operon and of the camR gene. Protection was inhibited by the addition of 60 microM D-camphor and also by certain camphor analogs and degradation products, including D-3-bromocamphor, adamantane, 2-adamantanone, 5-exo-hydroxycamphor, and 2,5-diketocamphane. These analogs and degradation products induced cytochrome P-450cam hydroxylase operon expression in vivo.

Base Sequence↗
PubMed1995

Enhanced nocturnal melatonin secretion in women with functional secondary amenorrhea: relationship to opioid system and endogenous estrogen levels.

The purpose of this study was to evaluate the role of the opioid system and the estrogen environment in the nocturnal secretion of melatonin in women with secondary amenorrhea (SA). Nocturnal melatonin concentrations in patients with SA were significantly higher than in normal women (p < 0.01 vs. women with normal menstrual cycles). There were significant negative correlations between cumulative melatonin levels (between 8 p.m. and 8 a.m.) and serum estradiol-17 beta (r = -0.561, p < 0.01) and between peak serum melatonin values and serum estradiol-17 beta concentrations (r = -0.608, p < 0.01) in SA. Intravenous administration of a conjugated estrogen (Premarin 20 mg) significantly suppressed nocturnal melatonin secretion (p < 0.05), but a continuous intravenous infusion of naloxone (1.6 mg/h from 8 p.m. to 6 a.m.), an opiate antagonist, did not affect nocturnal melatonin secretion in SA. Our findings suggest that elevated nocturnal melatonin secretion may be related to low estrogen levels, but that it is not mediated by the opioid system.

Adolescent↗
PubMed1995

[Long-term study of patients with sequelae of pulmonary tuberculosis after pneumonectomy--obstructive impairment and its causes].

Changes in pulmonary function, chest X-ray films, and CT were retrospectively studied in patients with sequeae of pulmonary tuberculosis 30 years after pneumonectomy (PNX). Over more than 10 years, VC and FEV1% changed at a rate of 23.2 +/- 8.8 ml and 0.683 +/- 0.688% per year, respectively. In the patients studied 30 years after PNX (N = 30), VC was 900 +/- 210 ml, %VC 31.6 +/- 8.1%, and FEV1% was 67.2 +/- 6.8%. About half of these patients had mild airway obstruction. FEV1% was negatively related to the distance from the hilum to the diaphragm on the mid-clavicular line (on the chest films) divided by body height (r = -0.607). Therefore, we think that the airway obstruction may be due to overextension of the bronchi of middle and lower lobes. Emphysema was not found in 18 patients who had no sign of hyperinflation or herniation of the remaining lung to the PNX side on their CT, but it was found in one patient with these signs.

Adult↗
PubMed1994

Iminodipeptides containing proline with C-terminal and N-terminal residues prime the stimulation of human neutrophil superoxide generation by fMLP.

Preincubation of human peripheral blood polymophonuclear leukocytes with an iminodipeptide containing proline at the C-terminus and/or N-terminus, Pro-Pro, Gly-Pro, Pro-Gly, Ala-Pro and Pro-Ala, significantly enhanced N-formyl-methionyl-leucyl-phenylalanine-induced superoxide generation in a concentration-dependent manner. The iminodipeptide with C-terminal proline showed higher effect than that of the counterpart with N-terminal proline. These iminodipeptides also enhanced the superoxide generation induced by opsonized zymosan but not that induced by arachidonic acid or phorbol myristate acetate. Tyrosyl phosphorylation of the 45-kDa protein occurred in parallel with the iminodipeptide-dependent enhancement of superoxide generation in neutrophil.

Amino Acid Sequence↗
PubMed1994

Heterologous expression of the cytochrome P450cam hydroxylase operon and the repressor gene of Pseudomonas putida in Escherichia coli.

The cytochrome P450cam hydroxylase operon (camDCAB) of Pseudomonas putida is negatively regulated by a repressor, CamR, which also represses its own gene. The expression in P. putida of both camR and camDCAB is derepressed in the presence of D-camphor. We examined the expression in Escherichia coli of camR and camDCAB by monitoring the enzyme activity of the camD gene product. In the presence or absence of D-camphor in the cell culture, the expression in E. coli of camD was significant and constitutive, suggesting no expression of camR. This lack of expression was confirmed by monitoring the beta-galactosidase activity of camR-lacZ translational fusions. However, S1 nuclease mapping revealed that synthesis of camR mRNA in E. coli was significant and constitutive, as observed in the case of camDCAB mRNA. Thus, it is likely that the expression of camR in E. coli is limited at the translational level.

Camphor↗
PubMed1994

Significant contribution of arginine-112 and its positive charge of Pseudomonas putida cytochrome P-450cam in the electron transport from putidaredoxin.

Cytochrome P-450cam of Pseudomonas putida is a prototype of various eukaryotic cytochrome P-450 molecules. Arg-112 located on the surface of this protein is highly conserved among various other cytochromes P-450. In this study, we constructed mutant genes for P-450cam in which Arg-112 was replaced by Gln or Glu, expressed them in Escherichia coli and purified the mutant proteins. Their enzymic activities were analyzed in the reconstituted system to determine the function of Arg-112. Kd values for d-camphor of Arg112-Gln and Arg112-Glu were much the same as those of the wild-type enzyme, whereas Kd values for the oxidized form of putidaredoxin, which is an acidic protein and is the redox partner of P-450cam, were 240 and 530 microM, respectively. These values are 8 and 19 times larger than that of the wild-type enzyme (28 microM), thereby indicating lower affinities of the mutant enzymes for the oxidized putidaredoxin. Reaction rate constants for reduction by the reduced form of putidaredoxin, measured using the stopped flow method, were 45.5, 9.0 x 10(-3) and 9.0 x 10(-4) s-1 for the wild type, Arg112-Gln and Arg112-Glu, respectively. Thus, Arg-112 of P-450cam plays an important role in the interaction with putidaredoxin and in the high efficiency of the electron transfer; the positive charge of the residue seeming to contribute to the process. The yields in Escherichia coli, the heme contents in the purified fractions and heat stability of the mutant proteins were lower than those of the wild type enzyme, suggesting that Arg-112 of P-450cam is also important for stability of P-450cam.

Arginine↗
PubMed1994

Putative functions of phenylalanine-350 of Pseudomonas putida cytochrome P-450cam.

Cytochrome P-450cam hydroxylates d-camphor, using molecular oxygen and reducing equivalents transferred via putidaredoxin. We constructed mutant genes in which Phe-350 of P-450cam was replaced by Leu, Tyr, or His by site-directed mutagenesis, expressed them in Escherichia coli, purified the mutant proteins, and compared their enzymic properties with those of the wild type P-450cam. NADH oxidation rate of the Tyr mutant in the reconstituted system with putidaredoxin and putidaredoxin reductase was similar to that of the wild type enzyme, while the Leu mutant and the His mutant showed 67% and 17% activity of that of the wild type, respectively. The affinities of these mutant proteins for camphor and the oxidized form of putidaredoxin were much the same as those of the wild type protein. Rate constants for the reduction reaction of P-450cam by reduced putidaredoxin, a physiological electron donor for P-450cam, of Tyr and His mutants were much the same as that of the wild type enzyme, whereas the Leu mutant showed approx. half that of the wild type. Thus, the aromatic ring of Phe-350 of P-450cam probably contributes to enhancing efficiency of the electron transfer yet does not seem to be essential for the reaction.

Base Sequence↗
PubMed1994

Nucleotide sequence of the gene encoding a repressor for the cytochrome P-450cam hydroxylase operon on the Pseudomonas putida CAM plasmid.

The camR gene of Pseudomonas putida encodes a repressor which regulates expression of the cytochrome P-450cam hydroxylase operon (camDCAB). We determined the nucleotide sequence of 1134 continuous base pairs, including the camR gene. When comparing the amino acid sequence deduced from the open reading frame of the gene sequence with that of amino-terminal five residues of the cam repressor, purified from Pseudomonas putida, we found that the camR gene encodes a protein of 186 amino acids, with a molecular mass of 20.4 kDa. The start codon for the cam repressor is the rare initiation codon GTG. The cam repressor predicted from the camR sequence contained a region similar to that seen in other DNA-binding proteins.

Amino Acid Sequence↗
PubMed1994

Intracellular signaling through long-range linked functions in the Ca2+ transport ATPase.

The Ca2+ transport ATPases of intracellular membranes exhibit an intracellular long-range functional linkage which is the basic mechanistic device for Ca2+ transport through ATP utilization. The functional linkage operates between a phosphorylation (catalytic) domain located in the extramembranous region, and a Ca2+ binding domain located in the membrane bound region of the enzyme. The two domains are separated by a distance of approximately 50 A, and are both affected by binding of a single molecule of the highly specific inhibitor, thapsigargin, to the enzyme. Functional and structural features are here described to explain the long-range linkage through the protein structure.

Amino Acid Sequence↗
PubMed1994

High detection rate of breast cancer by mass screening using mammography in Japan.

A trial of mass screening for breast cancer using both mammography and physical examination (independently) was carried out in women over 50 years of age in Tokushima Prefecture. Breast cancer was detected in eight of a total of 950 examinees by mammography alone, and no cases of breast cancer were detected by physical examination. The detection rate of breast cancer was 0.84%, which is very much higher than that obtained by conventional mass screening using physical examination alone. The detection rate increased especially in the sixth and seventh decades of life. All eight detected breast cancers were in the early stage. Based on these results, it is recommended to employ mammography in breast cancer screening for asymptomatic women aged over 50 years.

Adult↗
PubMed1994

Amplification of nocturnal melatonin secretion in women with functional secondary amenorrhoea: relation to endogenous oestrogen concentration.

BACKGROUND AND OBJECTIVE: Although there is extensive evidence that melatonin inhibits gonadotrophin secretion in animals, there is a parity of data on the relation between melatonin and ovarian function in humans. The purpose of this study was to evaluate the relation between endogenous oestrogen concentrations and nocturnal melatonin secretion occurring in patients with secondary amenorrhoea (SA). DESIGN AND PATIENTS: Nocturnal serum melatonin concentrations were determined in 20 women with SA, 5 women with endometriosis showing normal menstrual cycles and 11 volunteers with normal menstrual cycles. MEASUREMENT: Serum melatonin concentrations were determined by high performance liquid chromatography with electrochemical detection. Differences in melatonin concentrations were examined by analysis of variance. RESULTS: Nocturnal melatonin concentrations in patients with SA were significantly higher than in normal women (P < 0.01 vs women with normal menstrual cycles). There were significant negative correlations between cummulative melatonin levels (between 2000 and 0800 h) and serum 17 beta-oestradiol (r = -0.561, p < 0.01) and between peak serum melatonin values and the serum 17 beta-oestradiol (r = -0.608, P < 0.01) in SA. Intravenous administration of a conjugated oestrogen (Premarin 20 mg) significantly suppressed nocturnal melatonin secretion (P < 0.05). A low oestrogen state, induced by long-term (3.5 months) GnRH agonist treatment (900 micrograms/day of buserelin acetate) of the women with endometriosis produced an increase in nocturnal melatonin secretion comparable to that found in SA women. CONCLUSION: Our findings suggest that elevated nocturnal melatonin secretion in women with secondary amenorrhoea may be related to their low oestrogen concentrations.

Adolescent↗
PubMed1994

Serotonin metabolism in the fetus in preeclampsia.

We investigated serotonin (5-HT) metabolism in the fetus in preeclampsia by measuring free 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan concentrations in umbilical cord plasma and amniotic fluid, and 5-HT content in platelets by high performance liquid chromatography with electrochemical detection. Free 5-HT and 5-HIAA levels in umbilical cord plasma were significantly higher in the severe preeclamptic group (S) than those in the non-preeclamptic group (N). The plasma 5-HIAA/5-HT ratio in group S was significantly lower than that in group N. Platelet 5-HT content in group S tended to be lower than that in group N. Mean plasma beta-thromboglobulin concentration in group S was significantly higher than that in group N. There was no significant difference in plasma tryptophan levels between group S and N. These findings suggest that the higher levels of plasma free 5-HT in umbilical cord plasma in preeclampsia are attributable to excess release of 5-HT from platelets as well as lower monoamine oxidase activity.

Female↗
PubMed1994

Stimulation of prolactin secretion by melatonin is not mediated by opioids.

To clarify the role the opioid system plays in mediating the stimulation of prolactin release by melatonin, we performed two separate studies between the 6th and 8th days of the follicular phase in normal young women. In the first study, serum prolactin concentrations were determined every 20 min over a 4-hour period following oral administration of melatonin (1 mg given at 13.00 h) in the presence of continuous intravenous infusion of saline or naloxone (1.6 mg/h), an opiate antagonist. In the second study, plasma beta-endorphin concentrations were measured over a 3-hour period following oral melatonin administration (1 mg given at 13.00 h). Oral melatonin administration alone induced a significant increase in serum prolactin concentration, which was maximal 3 h after melatonin administration. Prolactin release following melatonin administration was not affected by continuous intravenous infusion of naloxone. No significant change in plasma beta-endorphin concentrations was observed following melatonin administration. These findings strongly suggest that the stimulation of prolactin release by melatonin is not mediated by opioids.

Adult↗
PubMed1994

[The pulmonary air meniscus sign in a case of sclerosing hemangioma].

A 57-year-old woman was admitted to our hospital because of a slowly growing pulmonary tumor with a 34 year history. Chest roentgenogram on admission showed a 42 mm sharply demarcated solitary tumor in the left upper lobe. Chest CT revealed a slit-like pulmonary air meniscus. Left upper lobectomy was performed. A specimen from the resected lung histologically showed solid, papillary and hemorrhagic patterns, and the diagnosis of pulmonary sclerosing hemangioma was therefore made. Pulmonary air meniscus sign in pulmonary sclerosing hemangioma is rare. We think one possible mechanism in the production of an air meniscus sign in sclerosing hemangioma is bleeding in communication with a bronchus.

Female↗
PubMed1994

[Identification of the most appropriate time for lung transplantation in the patients with idiopathic interstitial pneumonitis].

In order to identify the most appropriate time for lung transplantation, we examined the natural courses of eight patients who died of idiopathic interstitial pneumonitis (IIP). Five of eight patients died within two years after they were diagnosed as IIP and six died within one year after the last admission. As the disease progressed, arterial oxygen pressure tended to decrease and serum LDH level to increase. But no parameter was able to predict the natural courses of patients. We conclude that it is very difficult to identify the most appropriate time for lung transplantation and the prognosis of IIP patient is very poor. Therefore as soon as patients are diagnosed as IIP, it is mandatory to assess their eligibility for lung transplantation.

Adult↗