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Biomedical subjects

K Okamoto

Publications and source records attributed to K Okamoto.

At least 397 records · Page 22Linked to original sources
PubMed1998

Inhaled nitric oxide followed by extracorporeal membrane oxygenation in resuscitating a newborn with hypoxemia.

In a newborn requiring cardiopulmonary resuscitation because of hypoxemia due to sepsis (oxygenation index > 40), inhalation of nitric oxide (NO) in a concentration of 16 p.p.m. improved oxygenation and restored spontaneous circulation. Cannulation for extracorporeal membrane oxygenation (ECMO) then was performed safely under NO inhalation. ECMO was discontinued on day 7, and on day 14 the infant was extubated. During follow-up examination at 5 months of age no neurological abnormalities were found. This case shows the usefulness of combining inhaled NO and ECMO.

Bacteroides Infections↗
PubMed1998

Maternal-fetal transfer of melatonin in pregnant women near term.

Our objective was to evaluate the maternal-fetal transfer of melatonin in pregnant women. Serum melatonin concentration was measured by high-performance liquid chromatography with electrochemical detection in a maternal vein and in the umbilical artery and umbilical vein at the time of birth. Blood samples were obtained from 12 women who had spontaneously delivered vaginally at night. A single oral dose of melatonin was administered to each of 33 patients who underwent a cesarean section, and, blood samples were taken at 1, 2, 3, or 4 hr after the administration of melatonin at delivery. Cesarean section was performed between 1300 and 1500 hr. The mean melatonin concentrations of melatonin in maternal peripheral venous blood and umbilical arterial and umbilical venous blood did not differ significantly, and positive correlations in the serum levels of melatonin were observed between the three sources of blood. The oral administration of 3 mg of melatonin to pregnant women led to marked increases in the serum levels of melatonin, with maximum levels observed 2 hr (21.84 +/- 2.09 ng/ml) after drug administration. Changes in serum levels of melatonin in the umbilical vein and artery resembled those found in the maternal vein. Serum melatonin concentrations did not differ significantly between the maternal vein and the umbilical veins. Serum levels of melatonin in the umbilical vein after the administration of melatonin were significantly and closely correlated with those in the maternal vein (r = 0.924, P < 0.001). These results suggest that, in humans, melatonin is transferred from the maternal to the fetal circulation both easily and rapidly. A potential for the therapeutic use of melatonin as an antioxidant exists in the patients with preeclampsia.

Adolescent↗
PubMed1998

Characterization of the MexC-MexD-OprJ multidrug efflux system in DeltamexA-mexB-oprM mutants of Pseudomonas aeruginosa.

Expression of the multidrug efflux system MexC-MexD-OprJ in nfxB mutants of Pseudomonas aeruginosa contributes to resistance to fluoroquinolones and the "fourth-generation" cephems (cefpirome and cefozopran), but not to most beta-lactams, including the ordinary cephems (ceftazidime and cefoperazone). nfxB mutants also express a second multidrug efflux system, MexA-MexB-OprM, due to incomplete transcriptional repression of this operon by the mexR gene product. To characterize the contribution of the MexC-MexD-OprJ system to drug resistance in P. aeruginosa, a site-specific deletion method was employed to remove the mexA-mexB-oprM region from the chromosome of wild-type and nfxB strains of P. aeruginosa. Characterization of mutants lacking the mexA-mexB-oprM region clearly indicated that the MexC-MexD-OprJ efflux system is involved in resistance to the ordinary cephems as well as fluoroquinolones and the fourth-generation cephems but not to carbenicillin and aztreonam. Rabbit polyclonal antisera and murine monoclonal antibody against the components of the MexA-MexB-OprM system were prepared and used to demonstrate the reduced production of this efflux system in the nfxB mutants. Consistent with this, transcription of the mexA-mexB-oprM operon decreased in an nfxB mutant. This reduction appears to explain the hypersusceptibility of the nfxB mutant to beta-lactams, including ordinary cephems.

Animals↗
PubMed1998

Contribution of the disulfide bond of the A subunit to the action of Escherichia coli heat-labile enterotoxin.

Escherichia coli heat-labile enterotoxin (LT) consists of an A subunit and five B subunits. These subunits oligomerize into an assembled holotoxin within the periplasm. Structural analysis of LT has revealed that the A subunit interacts with the B subunit through its carboxy terminus. This indicates that the carboxy-terminal portion of the protein is required for assembly of holotoxin in the periplasm. However, it is not known whether other regions of the A subunit contribute to the assembly. The A subunit constituting the holotoxin contains a disulfide bond between Cys-187 and Cys-199. It has been observed in many proteins that the intramolecular disulfide bond is deeply involved in the function and tertiary structure of the protein. We speculated that the disulfide bond of the A subunit contributes to the assembly in the periplasm, although the bond is not a structural element of the carboxy-terminal portion of the A subunit. We replaced these cysteine residues of the A subunit by oligonucleotide-directed site-specific mutagenesis and analyzed the LTs produced by cells containing the mutant LT genes. The amount of the mutant holotoxin produced was small compared with that of the wild-type strain, indicating that the disulfide bond of the A subunit contributes to the structure which functions as the site of nucleation in the assembly. A reconstitution experiment in vitro supported the notion. Subsequently, we found that the mutant A subunit constituting holotoxin is easily degraded by trypsin and that in cells incubated with mutant LTs, the lag until the intracellular cyclic AMP begins to accumulate is longer than in cells incubated with native LTs. These results might be useful for the analysis of the interaction of LT with target cells at the molecular level.

Amino Acid Sequence↗
PubMed1998

Collagenofibrotic glomerulonephropathy associated with immune complex deposits.

A 66-year-old Japanese male, who suffered from persistent proteinuria and leg edema, underwent renal biopsy. Light microscopy revealed marked narrowing of the glomerular capillary lumen with a diffuse accumulation of weakly PAS-positive material. By electron microscopy, abundant abnormal collagen fibers were observed predominantly in the subendothelial space and occasionally in the mesangial matrix. The fibers had a periodicity of about 60 nm and were immunoreactive for anti-type III collagen. Subendothelial electron-dense deposits were also found in some of the capillary walls. The serum level of procollagen III peptides was elevated and changed in parallel with the amount of proteinuria during the patient's clinical course. On the basis of these findings, a diagnosis of the collagenofibrotic glomerulonephropathy was made. A review of the literature, including 29 similar or identical cases, failed to reveal the etiology and pathogenesis of this disease. We suggest that this disease may be divided into two different clinical subtypes, an adult-onset type and a pediatric type.

Aged↗
PubMed1998

In vivo investigation of glutamate-glutamine metabolism in hyperammonemic monkey brain using 13C-magnetic resonance spectroscopy.

To investigate the metabolism of glutamate and glutamine in living monkey brain, a system of in vivo 13C magnetic resonance spectroscopy (MRS) using 1H-decoupled 13C spectroscopy combined with monitoring temperature changes in the brain by MR phase mapping was developed. Serial 13C-NMR spectra of the amino acids glutamate and glutamine were acquired non-invasively over 4 h from anesthetized monkey brain after the intravenous administration of [1-13C]glucose (0.5-1.0 g/kg). In the acute hyperammonemic state induced by the administration of ammonium acetate (77 mg/kg bolus), it was observed that 13C incorporation into glutamine-4 was clearly accelerated, without changes of 13C incorporation into glutamate-4. During hyperammonemia, it was shown directly by [2-13C]glucose administration that the anaplerotic pathway for the TCA cycle was also augmented, contributing to the formation of glutamine in the astroglia.

Acetates↗
PubMed1998

RGD peptides regulate the specific adhesion scheme of osteoblasts to hydroxyapatite but not to titanium.

Hydroxyapatite (HA) is a bioactive dental implant material which accelerates bone formation on its surface. The mechanism of this acceleration is not clear. The elucidation of the cell adhesion might be the key to the understanding of the bioactive mechanism of HA. In this study, we analyzed the adhesion of HOS human osteoblasts onto HA and titanium to find the particular adhesion to HA. In short-term cultures in fetal bovine serum-pre-coated materials, a significantly higher number of cells adhered to HA than to titanium. In addition, serum-free conditions with phosphate-buffered saline pre-coating or bovine serum albumin pre-coating materials were tested. The results were nearly the same among all pre-coating conditions, suggesting that the quantity of cell adhesion was not affected by serum components. However, in the morphological observations by SEM, the form of adhesion was found to differ among pre-coating conditions. The osteoblasts tightly adhered and spread onto both HA and titanium with serum pre-coating, whereas the cells loosely adhered and did not spread without serum. To evaluate the Arg-Gly-Asp (RGD) sequence-specific adhesion, we used synthetic RGD peptides for a competitive inhibition test. The results showed that RGD peptides remarkably inhibited the tight adhesion and spreading of osteoblasts onto HA, whereas they did not strongly inhibit adhesion and spreading onto titanium. These results demonstrate that the regulation of cell adhesion to HA is different from that to titanium. Our study suggests that the RGD-containing serum proteins might have a major role in regulating the specific adhesion of osteoblasts to HA, and in inducing enhanced cell growth and differentiation.

Amino Acid Sequence↗
PubMed1998

[Geographication of centenarians and its related factors in Japan].

This study explores the factors associated with longevity in Japan by considering the geographic distribution of centenarians based on the 1990 population census. The proportion of centenarians was calculated based on the population of those aged 65 years or older. The findings were 11.0 males and 28.2 females per 100,000 people aged 65 years or older. In this analysis, the rate ratio, RR, was used as an index for fluctuation of centenarians by prefecture. RR is also the proportion of centenarians in a prefecture to that in the nation. When the RR of both sexes is over 100, the region is defined as high proportion and less than this as low proportion. The high proportion regions were located in the western part of Japan i.e. from the Chugoku to the Kyusyu district, the low proportion regions were located in the eastern part of Japan i.e. from the Tohoku to the Kanto district both sexes. The relationship between the geographical distribution of centenarians and environmental factors was analyzed. The correlation coefficient of the proportion of centenarians and the temperature as index of a regional difference was the highest among the factors investigated. After adjusting for mean temperature, the mean value of factors associated with a high quality of welfare work and of medical service, and that of having leisure time were significantly higher in high proportion regions than in low proportion regions.

Aged↗
PubMed1998

Expression of the extracellular levansucrase and invertase genes from Zymomonas mobilis in Escherichia coli cells.

We investigated the expression and localization in Escherichia coli of sucZE2 and sucZE3, encoding Zymomonas mobilis extracellular levansucrase and invertase, respectively, and lacking a typical N-terminal secretion signal. Levansucrase and invertase were expressed efficiently under the lac and tac promoters in E. coli cells, and some of the levansucrase produced was localized in the periplasmic space. The sucZE2 expression was not lethal to E. coli in the presence of 5% sucrose, and led to the accumulation of levan from sucrose.

Amino Acid Sequence↗
PubMed1998

Changes of platelet cytoskeletal proteins following platelet aggregation induced by collagen and platelet membrane glycoprotein in Japanese black cattle with delta-storage pool deficiency.

Five Japanese Black cattle showing the tendency of persistent hemorrhage were diagnosed as delta-storage pool deficiency because of lack of dense bodies in platelets. There was no significant difference in the platelet count, fibrinogen concentration, prothrombin time and activated partial thromboplastin time between the cases and normal control cattle. However, the maximum platelet aggregation rate and the values of myosin in the cytoskeletons during platelet aggregation induced by collagen were significantly lower in the cases compared with those in normal control cattle. The quantities of platelet membrane glycoprotein were in the range of 94-160 kDa and were not different between the cases and control cattle. However, a decrease of thrombospondin in alpha-granules in platelet cytoplasm were suspected in two of the 5 cases.

Animals↗
PubMed1998

Efficacy of inhaled nitric oxide in children with ARDS.

STUDY OBJECTIVE: Data concerning inhaled nitric oxide (iNO) on pediatric ARDS is rare. We investigated the effects of iNO on pediatric ARDS in order to examine the ability to predict a response to iNO, the optimal concentration of iNO, the effects of < or = 1 ppm nitric oxide (NO), and the effect of iNO on PaCO2. SETTING: ICU at Kumamoto (Japan) University Hospital. PATIENTS AND INTERVENTIONS: Seven children with ARDS. The initial responses to 16 ppm NO and the dose-response effects of 0.13 to 16 ppm NO were assessed. MEASUREMENTS AND RESULTS: Sixteen ppm of iNO improved oxygenation in all seven children. The use of iNO significantly increased the ratio of arterial oxygen tension to the fraction of inspired oxygen (PaO2/FIO2). A correlation between the NO-induced increase in PaO2/FIO2 and the baseline PaO2/FIO2 was observed (r=0.93, p<0.01). Dose-response tests showed that the optimal concentration of iNO was < or = 4 ppm, improvements in PaO2/FIO2 could be observed with concentrations of < or = 1 ppm NO, and iNO induced a slight decrease in PaCO2. CONCLUSIONS: In children with ARDS, iNO frequently improves oxygenation and induces a slight decrease in PaCO2, with the baseline PaO2/FIO2 functioning as a predictor of all NO response. Improvements of PaO2 and PaCO2 were observed with concentrations of iNO of < or = 1 ppm, a level in which the risk of a toxic reaction in children is minimal. Effects on outcome need verification in larger controlled trials.

Administration, Inhalation↗
PubMed1998

Mp colorectal cancer should be defined as early colorectal cancer.

Little is known about the clinicopathologic features of mp colorectal cancer, defined as a cancer where the depth of invasion is limited to within the mucosa, the submucosa and the proper muscle. This study was designed to determine the clinicopathologic features of mp colorectal cancers. From 1973 to 1993, 83 mp colorectal cancer and 66 sm colorectal cancer patients were treated in our department and were enrolled in this study. During the same period, 66 patients with sm colorectal cancer defined as a cancer where the depth of invasion is limited to within the mucosa and the submucosa, were treated. The clinicopathologic findings of these patients were determined retrospectively from their hospital records. Clinicopathologic differences in sm and mp colorectal cancers were compared with sm and mp gastric cancers. The incidence of mp colorectal cancer increased from 7.9% in 1973-1977 to 16.2% in 1988-1993. An advanced macroscopic appearance, a larger tumor size, lymph node metastasis and lymph vessel invasion were more predominant in mp than sm colorectal cancer. Multivariate analysis demonstrated that these clinicopathologic factors were not statistically independent prognostic factors for mp colorectal cancer patients. There was no statistical difference in postoperative survival between sm and mp colorectal cancer patients. Mp colorectal cancer should be defined as early colorectal cancer, because the postoperative survival rate does not differ between mp and sm colorectal cancers, and the clinicopathologic differences between these two are negligible.

Colorectal Neoplasms↗
PubMed1998

A survey of bedroom and bed climate of the elderly in a nursing home.

Bedroom and bed climate of the elderly in a nursing home were surveyed. Twenty-two elderly subjects were divided into four groups depending on their Activity of Daily Living (ADL) and gender. The four groups were: male and female subjects with almost no problems in daily life and an ADL score higher than 5 [H males, H females] and male and female subjects who normally stayed in bed all day with an ADL score lower than 2 [L males, L females]. The temperature and humidity of the bedroom and bed climate were measured continuously for 24 hours. Bedding and clothing condition, subjective sensational vote and subjective sleep evaluation were surveyed before and after sleep for five days continuously. In the daytime, bedroom and bed climate temperature was significantly lower in H females than in the other groups. At night, no significant effect of gender and ADL was observed in bed climate, which was maintained at 33-35 degrees C, RH50-60% in all the groups. Bedding under the body increased significantly in L males and L females compared with H males and H females. The number of underwear increased significantly in H females. Subjective sleep evaluation was significantly better in H females than the other groups. These results suggest that ADL and gender based differences should be taken into account with regard to the care of the elderly in a nursing home.

Activities of Daily Living↗
PubMed1998

Effects of truss mattress upon sleep and bed climate.

The purpose of this study was to examine the effects of a truss mattress upon sleep and bed climate. The truss mattress which has been designed to decrease the pressure and bed climate humidity was tested. Six healthy female volunteers with a mean age of 23.3 years, served as subjects. The experiment was carried out under two conditions: a truss mattress (T) and a futon (F) (Japanese bedding). The ambient temperature and relative humidity were controlled at 19-20 degrees C, and RH 50-60% respectively. Sleep was monitored by an EEG machine and the rectal temperature, skin temperature and bed climate were also measured continuously. Subjective evaluations of bed and sleep were obtained before and after the recording sessions. No significant difference was observed in the sleep parameters and time spent in each sleep stage. Rectal temperature was significantly lower in T than F. Although there was no significant difference in bed climate over the T/F, the temperature under T/F was significantly higher in T. No significant difference was observed in subjective sleep evaluation. The subjective feeling of the mattress was significantly warmer in F than T before sleep. These results suggest that although T does not disturb the sleep parameters and the bed climate is maintained at the same level as with F, it may affect rectal temperature which can be due to low thermal insulation.

Adult↗
PubMed1998

Plasma (1-->3)-beta-D-glucan measurement and polymerase chain reaction on sputum as practical parameters in Pneumocystis carinii pneumonia.

We report a case of Pneumocystis carinii pneumonia in a patient with acquired immunodeficiency syndrome diagnosed and monitored with polymerase chain reaction (PCR) for Pneumocystis carinii on sputum and measurement of plasma (1-->3)-beta-D-glucan (G-test). Results of both studies paralleled the clinical and radiographic improvement. However, the plasma (1-->3)-beta-D-glucan level remained higher than normal when PCR for Pneumocystis carinii became negative in sputum. Both PCR for Pneumocystis carinii on sputum and measurement of plasma (1-->3)-beta-D-glucan are useful for noninvasive diagnosis and monitoring of Pneumocystis carinii, although further investigation is necessary to quantify their relationship.

AIDS-Related Opportunistic Infections↗
PubMed1998

Distribution of dehydroepiandrosterone sulfate and relationships between its level and serum lipid levels in a rural Japanese population.

Dehydroepiandrosterone sulfate (DHEAS) is a major secretory product of the adrenal glands. DHEAS is inversely associated with death from cardiovascular disease in males, but not in females. This cross-sectional study examined the relationships between serum DHEAS levels and atherosclerosis in free living subjects in Japan. We measured the serum DHEAS levels of 990 apparently healthy subjects aged 35-81 years old in a rural area in Japan; 431 males and 559 females. The levels were determined by the radioimmunoassay method. The frequency distribution was skewed to a lower value in both sexes. Both unadjusted and age-adjusted mean DHEAS levels were statistically higher in males than in females, A marked linear decline of levels with age was observed in both sexes. DHEAS levels were positively correlated with high density lipoprotein-cholesterol (HDLC), and negatively correlated with low density lipoprotein-cholesterol (LDLC) even after adjustment for age in both sexes. The mean atherogenic index (AI) was significantly inversely correlated with the rise of tertiles of the DHEAS level, both before and after adjustment for age, Total cholesterol (TC), HDLC and Triglyceride (TG). These results suggest high levels of serum DHEAS may have an inhibitory effect on the development of atherosclerosis and have an important role in its etiology and prevention.

Adult↗