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Biomedical subjects

R Sato

Publications and source records attributed to R Sato.

At least 307 records · Page 17Linked to original sources
PubMed1988

Evaluation of a fluorescence polarization immunoassay procedure for quantitation of isepamicin, a new aminoglycoside antibiotic.

A fluorescence polarization immunoassay (FPIA) procedure for measuring isepamicin, a new aminoglycoside antibiotic, was evaluated. The range of the assay studied was from 0.3-50 micrograms/ml and the calibration curve can be stored for at least 32 days. There was no interference from hemoglobin (up to 400 mg/dl) and bilirubin (up to 20 mg/dl). Within-run precision on each 20 replicates at 5, 15, and 25 micrograms/ml yielded a coefficient of variation (CV) of 1.44-2.52%; between-run precision on analyses at 5, 15, and 25 micrograms/ml over five periods yielded a CV of 1.26-1.59%. Cross-reactivities of the assay system with tobramycin and amikacin were null, but that with gentamicin, of which isepamicin is a derivative, was approximately 14-29%. Data obtained by microbiological assay and FPIA and by high-performance liquid chromatography and FPIA correlated significantly, with coefficients of correlation being 0.980 (n = 70) and 0.965 (n = 39), respectively. The FPIA offers a rapid, efficient, and accurate system for therapeutic monitoring of isepamicin plasma levels.

Adult↗
PubMed1988

Regulation of multiple basic fibroblast growth factor messenger ribonucleic acid transcripts by protein kinase C activators.

The human astrocytoma cell line U87-MG expressed two major basic fibroblast growth factor (FGF) mRNA transcripts of 7.0 and 3.7 kilobase (kb), as well as several low abundance transcripts of lower mol wt (1.0-1.8 kb). The phorbol ester phorbol-12,13-dibutyrate caused a time- and dose-dependent increase in the abundance of basic FGF mRNA transcripts. At a concentration of 1 microM, phorbol ester increased the level of both the 7.0 and 3.7 kb transcripts within 4 h, reached a plateau at 1.5- to 2.5-fold above control levels by 6 h and remained elevated for at least 12 h. When measured at 6 h after drug addition, the abundance of both 7.0 and 3.7 kb transcripts was maximally stimulated by 100 nM phorbol ester (EC50 = 10-20 nM). FGF mRNA levels were also stimulated to a similar extent by platelet-derived growth factor (0.15-5 U/ml) or the synthetic diacylglycerol analog 1-oleoyl-2-acetyl-rac glycerol (1-300 nM) at doses which stimulated DNA synthesis in these cells. Neither (Bu)2cAMP (0.03-2 mM) nor A23187 (0.3-1000 nM) had any effect on FGF expression. When U87-MG cells were exposed to phorbol ester for 24 h several differences were observed: the dose response curve was shifted to the left (EC50 = 3-5 nM; maximum response at 10 nM phorbol ester) and the response of the 7.0 and 3.7 kb transcripts was attenuated at higher doses (100-1000 nM), perhaps reflecting down-regulation of protein kinase C by the phorbol ester.(ABSTRACT TRUNCATED AT 250 WORDS)

Astrocytoma↗
PubMed1988

Fibroblast growth factor messenger ribonucleic acid expression in a human astrocytoma cell line: regulation by serum and cell density.

A human astrocytoma cell line, U87-MG, synthesizes a growth factor which is structurally related to basic fibroblast growth factor (bFGF) by several criteria: 1) it binds to heparin-Sepharose and elutes at 2 M NaCl; 2) it cross-reacts with N-terminal specific anti-bFGF antibodies; 3) it is a potent mitogen for rabbit fetal chondrocytes. Northern blotting analysis of total RNA reveals that the cells express high levels of two bFGF mRNA transcripts of 7 and 3.7 kilobase in size. The levels of both transcripts rise rapidly (within 3 h) after addition of serum to serum-deprived cultures, reach a maximum within 6-12 h and remain elevated for at least 24 h. Basic FGF mRNA expression was low in confluent cultures but was increased after replating at sparse density. Transcript levels began to increase 4 h after plating, reaching a maximum (7-fold above confluent cells) within 24 h. The rise in bFGF mRNA levels was preceded by a rapid rise in c-myc expression which peaked 8 h after plating and then declined. The level of bFGF mRNA expression began to decline by 48 h, before any detectable increase in cell number, and returned to control levels when the cells reached confluence after 10 days. The level of transforming growth factor beta mRNA, which is also expressed in these cells, was not affected by cell density. The effects of density on bFGF mRNA levels were not duplicated by culturing low density cells in conditioned medium from confluent cultures or in medium containing 10 ng/ml bFGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Astrocytoma↗
PubMed1988

Silver-banded karyotypes of the rainbow trout and the brook trout and their hybrids: disappearance in allotriploids of Ag-NORs originated from the brook trout.

Silver-banded karyotypes of the rainbow trout Salmo gairdneri, the brook trout Salvelinus fontinalis, and their hybrids were described. Diploid-type and triploid-type hybrids were obtained. Triploid-type hybrids had two maternal genomes of the rainbow trout and one paternal genome of the brook trout. The rainbow trout had one pair of M or SM with Ag-NORs near the satellite. In the brook trout, Ag-NORs were observed in four pairs of chromosomes, but each cell had different number of chromosomes with Ag-NORs. In all observed cells of triploid-type hybrids, Ag-NORs originated from the brook trout were not recognized, whereas those from the rainbow trout were found.

Animals↗
PubMed1988

Prevalence of cardiovascular diseases in the Kingdom of Tonga.

The blood pressure, electrocardiographic findings and serum total cholesterol of Tongans, characterized by extreme obesity, were compared with those of Japanese employees of a trading firm in Tokyo. The prevalence of cardiovascular diseases in Tongans as far as assessed by these measurements was rather low for their excessive obesity. It is unclear whether the relatively low prevalence rate of cardiovascular diseases among the Tongans is due to genetic factors which might be considered an ethnological difference, or to environmental factors. Reducing weight is very difficult for many obese people. Accordingly, if "healthy obesity" exists, elucidation of its mechanism will be glad tidings for obese persons. However, the most prevalent diseases among the Tongans were the same as those of the developing countries. Consequently, imitating the Tongan lifestyle does not necessarily assure the longevity of obese persons of developed nations, although it may decrease the risk of the cardiovascular diseases.

Adult↗
PubMed1988

[Significance of perioperative nutritional support and activation of the reticuloendothelial system on the resection of the cirrhotic liver].

The cirrhotic patients were in poor nutritional condition and deteriorated reticuloendothelial function, which were further aggravated after hepatic resection. Preoperative nutritional repletion treatment as well as preoperative administration of OK-432 improved the nutritional condition and reticuloendothelial function of the patients, resulting in uneventful postoperative courses. In experimentally induced liver cirrhosis, however, an excessive amount of glucose administration in the early postoperative period induced the reduction of hepatic energy charge and ATP content. An adequate amount of glucose should be administered in a period associated with marked glucose intolerance. To determine daily glucose disposal rate rapidly, blood glucose curve obtained from intravenous glucose tolerance test (IVGTT) and insulin tolerance test (ITT) was analyzed in hepatectomized cirrhotic rats. It was possible to calculate prospected values of glucose disposal rate by the analytic index of IVGTT and ITT. An adequate perioperative nutritional support and the activation of the reticuloendothelial system are thought to have important therapeutic value to prevent complications of liver cirrhosis after resection.

Animals↗
PubMed1988

A fluorescence polarization immunoassay evaluated for quantifying astromicin, a new aminoglycoside antibiotic.

We evaluated a fluorescence polarization immunoassay (FPIA) procedure for measuring astromicin, a new aminoglycoside antibiotic. The calibration curve can be stored for at least 32 days without loss of accuracy. There were no interferences from hemoglobin (up to 4000 mg/L) or bilirubin (up to 200 mg/L), nor were there any cross-reactivities with amikacin, gentamicin, or tobramycin. Within-run precision (CV) for 20 replicates, each at concentrations of 5, 15, and 25 mg/L, was 1.25-2.11%. Between-run precision for these same concentrations, measured on five occasions, was 2.13-2.74%. Linear-regression analyses of data by FPIA (y) and HPLC (x) for plasma obtained from six healthy male volunteers who were given 200 mg of astromicin by 30-min intravenous infusion and for sera prepared by adding arbitrary amounts of astromicin showed highly significant correlations: r = 0.996 (n = 66), y = 0.96x - 0.48 mg/L and r = 0.981 (n = 59), y = 0.96x - 0.25 mg/L, respectively. This assay offers a rapid, efficient, and accurate system for therapeutic monitoring of astromicin in blood.

Adult↗
PubMed1987

Protein-protein and lipid-protein interactions in a reconstituted cytochrome P-450 dependent microsomal monooxygenase.

NADPH-cytochrome P-450 reductase and cytochrome P-450, both purified from liver microsomes of phenobarbital-treated rabbits, were incorporated into dimyristoylphosphatidylcholine vesicles. The reduction of cytochrome P-450 by NADPH in the reconstituted vesicles proceeded in a biphasic fashion, and 70-80% of the absorbance change was associated with the fast phase. The Arrhenius plot of the apparent first-order rate constant of the fast-phase reduction showed a marked discontinuity around the phase transition temperature of the synthetic phospholipid; an almost 10-fold change in rate constant was associated with this discontinuity. It was, therefore, suggested that the reduction of cytochrome P-450 by reductase in this system was a diffusion-limited reaction controlled by the viscosity of the phospholipid membrane. The Arrhenius plot of overall drug monooxygenase activity catalyzed by the reconstituted vesicles showed a break but in a different way from that observed for the reduction of cytochrome P-450. This break was accompanied only by a change of the slope of the plot but not by a change in reaction rate. This difference in the two Arrhenius plots was attributed to that in the rate-limiting step of the two reactions. NADPH-cytochrome c reductase activity of the reconstituted vesicles, an activity catalyzed by the reductase alone, and cumene hydroperoxide dependent N-methylaniline demethylation activity catalyzed by cytochrome P-450 alone did not show any break in the Arrhenius plots.

Animals↗
PubMed1987

[Reevaluation of serum TSH determination in various pituitary disorders using highly sensitive immunoradiometric assay].

In thirty-one patients with various pituitary disorders, their serum TSH levels were reevaluated using two kinds of highly sensitive immunoradiometric assays (IRMAs). TSH levels were measured by radioimmunoassay (RIA) supplied by Daiichi Radioisotope Laboratory and the IRMAs, which were RIA-gnost TSH Ultrasensitive and SUCROSEP TSH IRMA using two types of monoclonal antibodies. The sensitivities of them were 0.08 and 0.1 microU/ml, respectively. Free thyroxine and free triiodothyronine levels were measured by RIAs (Amerlex kits). There was a significant correlation between basal TSH levels and the maximum increase in serum TSH above baseline using the RIA and the IRMAs when responses to TRH (500 micrograms i.v.) was determined, but no correlation between basal TSH and thyroid free hormone levels. In their TRH tests, three patients showed absent responses to TRH which were measured by the RIA, although by the IRMAs slight responses were observed. In two patients, exaggerated responses to TRH were observed and the increase of TSH levels measured by the IRMAs showed 143 approximately 210% higher than that of the RIA. The IRMAs were able to handle their peak levels time in all the patients with responses, however, in some patients the RIA was not sensitive enough to distinguish it. These results indicated that measurement of TSH levels by the IRMAs might be useful in the evaluation of the TSH secretion capacity in patients with various pituitary disorders.

Humans↗
PubMed1987

A short amino-terminal segment of microsomal cytochrome P-450 functions both as an insertion signal and as a stop-transfer sequence.

Co-translational insertion of liver microsomal cytochrome P-450 into the endoplasmic reticulum membrane is mediated by the signal recognition particle (SRP) and the presence in the cytochrome molecule of a signal sequence that can be recognized by SRP has been postulated. To locate this signal sequence, six hybrid cDNAs were constructed in which various segments of a cDNA for a rabbit liver cytochrome P-450 are fused with a cDNA or its fragment encoding yeast porin (an outer mitochondrial membrane protein) or with a cDNA for pre-interleukin 2 (a secretory protein) from which the 5'-terminal portion encoding most of its signal sequence had been removed. These hybrid cDNAs were inserted into an SP-6 transcription vector and transcribed in vitro. The mRNAs thus synthesized were translated in a cell-free system in the presence of rough microsomes. It was thus found that only those chimeric proteins containing (at their amino-terminal end) the amino-terminal cytochrome P-450 segments consisting of greater than or equal to 29 amino acid residues were co-translationally inserted into the membrane in an SRP-dependent fashion. These proteins were, however, neither processed nor translocated across the membrane. These findings, coupled with the observation that the major portion of these proteins, when inserted into the membrane, was degraded by trypsin, led to the conclusion that a short amino-terminal segment (less than 29 residues) of the cytochrome P-450 functions not only as an insertion signal but also as a stop-transfer sequence. This segment is, therefore, similar to the internal signal of type II plasma membrane proteins, but differs from the latter in the topogenic function.

Amino Acid Sequence↗