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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 1,207 records · Page 67Linked to original sources
PubMed1988

Intestinal absorption of riboflavin, studied by an in situ circulation system using radioactive analogues.

The intestinal absorption of riboflavin was studied using radioactive riboflavin and its analogues 8-demethylriboflavin, 3-methylriboflavin, 5'-deoxyriboflavin, 2'-deoxyriboflavin, 7,8-dimethyl-10-hydroxyethylisoalloxazine, lumiflavin, lumichrome, and riboflavin-5'-monosulfate, which were synthesized with high specific radioactivity. A specific absorption of riboflavin at dietary concentrations was confirmed using an in situ circulation system. The relation between the chemical structure of flavins and the absorption mechanism was studied using this system. The 8-demethylriboflavin, an analogue modified at benzene moiety of the isoalloxazine ring, was absorbed in a similar way to riboflavin, by dual kinetics: by a process specific for riboflavin at dietary concentrations and by simple diffusion (nonspecific absorption) predominating at higher concentrations (over 100 microM). However, 3-methylriboflavin and analogues modified at the ribityl group, including 5'-deoxyriboflavin, were absorbed only via simple diffusion even at dietary concentrations. Many flavins examined, except for 3-isobutylriboflavin, 3-carboxymethylriboflavin, lumichrome, and riboflavin-5'-monosulfate, interfered with the specific absorption of riboflavin. It was concluded from these results that one of the specific absorption processes for riboflavin is a phosphorylation-dephosphorylation process. Four water-soluble vitamins did not interfere with the specific absorption of riboflavin, indicating that these vitamins do not share a common specific absorption pathway with riboflavin.

Animals↗
PubMed1988

[A study of the cardiotocograms recorded by a separated 1MHz ultrasound transducer].

Fetal heart rate records were obtained in 12 antepartum and 13 intrapartum cases, with an ultrasonic Doppler transducer with five separated crystals and a conventional transducer. The loss of the FHR record due to increased noise in 30 minutes before delivery ranged from 1.1 to 23.2% (6.4 +/- 6.5%) in the separate type transducer, and it was 0.6 to 29.9% (10.5 +/- 7.6%) in the conventional one. During the 5 minutes before delivery, it was 3.3 to 58.0% (20.2 +/- 18.5%) in the separate type, and 3.3 to 70.0% (31.6 +/- 19.5%) in the conventional one. Clearer FHR records were obtained with the use of the separate type than the conventional one (p less than 0.05). Noise was mostly recorded in the 5 minutes before delivery. In the NST, the loss of the FHR record due to maternal posture change decreased when the new transducer (p less than 0.05) was used. The loss was 0 to 56.7% (14.9 +/- 18.2%) with the new type, and 2.0 to 100% (42.9 +/- 36.4%) with the conventional one for the maternal posture which showed the worst record. By using the separate type transducer, maternal posture need not to be limited in the NST, and the somatic and mental discomfort is less than when the conventional one is used.

Female↗
PubMed1988

[Metabolic and nutritional management after extended radical operation for pancreatobiliary carcinoma].

The physiology after extended radical operation in patients with pancreatobiliary carcinomas and the metabolic and nutritional management were studied. Twenty-four patients who underwent pancreatoduodenectomy with extended dissection were compared with 17 patients with semi-extended dissection and 44 patients with limited or no dissection. Extended dissection meant complete dissection of the nerve plexus around the superior mesenteric artery and para-aortic node dissection. The frequency of defecation (2.7 times/day) and the blood osmolarity in the extended dissection group were significantly higher than those in the other groups during the first week after operation. The level of serum protein was significantly lower in the extended dissection group. Insulin dosage during the first 14 days after surgery was significantly greater in the extended dissection group, yet no difference was recognized in the amount of glucose administered among the 3 groups. The conclusion was as follows; frequent diarrhea, a large amount of lymph loss and increased urine volume due to an osmotic diuresis were the main causes of volume loss. So a large volume of fluid containing a high concentration of protein should be injected immediately after extended dissection to normalize serum osmotic pressure. Because of increased insulin requirement and decreased endogenous insulin production, the administration of large amount of glucose immediately after operation should be undertaken carefully.

Biliary Tract Neoplasms↗
PubMed1988

Accumulation of indoxyl sulfate, an inhibitor of drug-binding, in uremic serum as demonstrated by internal-surface reversed-phase liquid chromatography.

We quantified indoxyl sulfate in uremic serum by using internal-surface reversed-phase high-performance liquid chromatography. Its concentrations were markedly increased in chronic hemodialysis patients, and were significantly but weakly correlated with the concentrations of creatinine and beta 2-microglobulin in these patients' serum, and with the duration of their hemodialysis treatment. Indoxyl sulfate could not be removed effectively by conventional hemodialysis because of its strong binding to serum albumin. Equilibrium dialysis demonstrated that indoxyl sulfate inhibited the binding of salicylate to albumin, and that 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid inhibited the binding of indoxyl sulfate to albumin. In conclusion, indoxyl sulfate was markedly accumulated in uremic serum, and inhibited drug binding.

Albumins↗
PubMed1988

Effects of nilvadipine on the cardiovascular system in experimental animals.

The effects of 5-isopropyl 3-methyl 2-cyano-1,4-dihydro-6-methyl-4-(m-nitrophenyl)-3,5-pyridinedicarboxylate (nilvadipine, FR 34235, FK 235) on the cardiovascular system were investigated in isolated organs and whole animals. 1. Nilvadipine inhibited Ca2+-induced contractions of isolated dog coronary artery in high-K+, Ca2+-free medium, and the pA2 value was 10.64. In this effect, nilvadipine was 18 times more potent than nifedipine and 525 times more potent than diltiazem. In contrast, its inhibitory effect on Ca2+-induced contractions of isolated guinea pig atria was weaker (pA2:8.2): only twice that of nifedipine and 25 times that of diltiazem. 2. Nilvadipine also inhibited K+-induced 45Ca2+ uptake in isolated dog coronary arteries and isolated guinea pig atria. In the coronary arteries, the IC50 value of nilvadipine was 2.7 x 10(-10) mol/l, which was, respectively 17, 8, and 589 times lower than that of nifedipine, nicardipine and diltiazem. In the atria, on the other hand, the IC50 value of nilvadipine was 4.4 x 10(-9) mol/l, almost the same as that of nifedipine or nicardipine, and 47 times lower than that of diltiazem. These 45Ca2+ uptake inhibitory effects of the drugs were consistent with their effects on mechanical response in both tissues. 3. Nilvadipine (2.6 x 10(-10) mol/l and higher) dose-dependently inhibited ergometrine (ergonovine)-, serotonin-, and norepinephrine-induced contractions of isolated dog coronary artery, and its effects were 2 to 450 times more potent than those of nifedipine, nicardipine and diltiazem. 4. Nilvadipine (2.6 x 10(-8) mol/l or more, 32 micrograms/heart or more), like nifedipine, produced negative inotropic and chronotropic effects in isolated guinea pig atria and in dog heart-lung preparation, and was more potent than nifedipine in the negative chronotropic effect. 5. Nilvadipine in intravenous doses of 1-32 micrograms/kg decreased total peripheral resistance and systemic blood pressure, and slightly increased cardiac output, pulmonary arterial blood flow and stroke volume, but had no significant effects on pulmonary vascular resistance or pulmonary arterial blood pressure. Heart rate decreased at doses of 32 micrograms/kg or more. Nifedipine had almost the same effects as nilvadipine on total peripheral resistance and blood pressure, but was more potent than nilvadipine in increasing effects on cardiac output, stroke volume and pulmonary arterial blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Clinical effects of selective thromboxane A2 synthetase inhibitor in patients with nephrotic syndrome.

To determine if a selective thromboxane (TX)A2 synthetase inhibitor is clinically effective for the treatment of nephrotic syndrome, 11 patients with nephrotic syndrome were treated only with OKY-046, (E)-3-4-(1-imidazolylmethyl)phenyl-2-propenoic acid hydrochloride monohydrate, for at least 8 weeks. Urinary excretion of protein, TXB2, 2,3-dinor-TXB2, and beta-N-acetyl-D-glucosaminidase decreased with OKY-046. Creatinine clearance value, and urinary excretion of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), however, did not show any significant change, while serum albumin level increased. Two patients with minimal change nephrotic syndrome showed complete remission only with OKY-046. These results demonstrate that the selective TXA2 synthetase inhibitor is an effective drug for the treatment of chronic glomerulonephritis accompanied by nephrotic syndrome.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

[Studies on the cardiotocograms recorded by a new system with 1 MHz ultrasound and autocorrelation heart rate meter].

Improved FHR records were obtained by the use of a new 1 MHz ultrasound transducer and autocorrelation heart rate meter. The results were compared with conventional 2.5 MHz continuous wave ultrasound device. The rate of the loss of FHR recording was 0 to 6.6% (2.8 +/- 2.1%) in the new device, and it was 2.1 to 23.5% (8.7 +/- 6.2%) in the old one. The loss of FHR record in the 2nd stage of labor was 3.2% when 1 MHz ultrasound and new device were used, and it was 2.0% with direct fetal ECG signal using scalp electrode and the same device. More clear record was obtained with use of ultrasound at a crowning of fetal head than that of direct fetal ECG. In the use of 1 MHz ultrasound, 51% cases in 55 patients showed undisturbed FHR record 1 minute before delivery of the fetus. Slightly noisy but analysable FHR record was obtained in 36%. Hence, the FHR records were clearly evaluated until 1 minute before delivery of the infant in 87% of the cases. Maternal heart rate signal was mixed with FHR in 2 cases in routine intrapartum ultrasonic FHR monitoring. However, the maternal signal disappeared after moving the transducer to other position where fatal heart beat was more clearly detected.

Electrocardiography↗
PubMed1988

Nature and biosynthesis of structural matrix protein in melanosomes: melanosomal structural protein as differentiation antigen for neoplastic melanocytes.

Two major classes of protein, i.e., structural matrix and enzymic, exist in the melanosome. In normal melanocytes, synthesis of these two components is under a strict genetic control with regulatory steps associated with transcription and translation coded with appropriate pigment genes. In abnormal neoplastic melanocytes, they become markedly aberrant. The aberrant melanogenesis can be typically manifested by an abnormality in fine structure of the melanosome. The fine structural heterogeneity of the melanosome can often be diagnostic to certain forms of malignant melanoma and dysplastic melanocytic nevus. This study brings about the importance of the structural matrix protein for the expression of fine structural heterogeneity in the melanosome by developing the 2 monoclonal antibodies, MoAb HMSA-1 and HMSA-2. The 2 MoAbs recognized the cytoplasmic antigen on paraffin embedded sections, which under immunoelectron microscopy and cell fractionation studies, were found to be localization the melanosome and smooth ER, but not Golgi complex and coated vesicles as seen in the tyrosinase studies. It is indicated (a) that the sites of the synthesis for the melanosomal protein and tyrosinase are different, (b) that the melanosomal structural protein is accumulated in the dilated vacuole of smooth ER from which the stage I melanosome is synthesized, (c) that the synthesis of melanosomal protein becomes markedly aberrant and directly reflects the abnormal fine structure of the melanosome and (d) the heterogeneity in synthesis of melanosomal protein as expressed by MoAb HMSA-1 and HMSA-2 is a useful adjunct for immunohistopathological differentiation of malignant melanoma cells from benign nevoid cells and normal melanocytes.

Antigens, Differentiation↗
PubMed1987

Characterization of cDNA coding for the complete light meromyosin portion of a rabbit fast skeletal muscle myosin heavy chain.

Myosin-heavy-chain-specific cDNA clones have been isolated from a cDNA library prepared from hind leg muscle of a 14-day-old rabbit. According to restriction enzyme analysis these can be grouped into at least two, probably three different classes. RNA dot-blot hybridization shows that all of these clones correspond to mRNAs expressed in fast skeletal muscle. The clones of the most abundant form, class I, can be aligned to cover the complete light meromyosin portion of myosin heavy chain. The sequence of the coding and the 3'-untranslated region, together comprising 2143 base pairs, has been determined. The class I clone detects a multigene family of 8-12 members on a Southern blot of rabbit genomic DNA.

Amino Acid Sequence↗
PubMed1987

Thiamin uptake in Euglena gracilis.

Thiamin uptake has been investigated in Euglena gracilis Z. This protozoon possessed an active transport system for thiamin with a Km value of 17 nM and a Vmax value of 7.8 pmol per 10(6) cells per min. Thiamin uptake was dependent on pH and temperature, but not on exogenous glucose as an energy source. Oxythiamin and pyrithiamin were competitive inhibitors with Ki values of 33 nM and 15 nM, respectively. Thiamin monophosphate, thiamin pyrophosphate, thiamin triphosphate, heteropyrithiamin, quinolinothiamin, thiamin chloride and amprolium inhibited uptake. Inhibition of thiamin uptake by various metabolic inhibitors and anaerobiosis suggest that thiamin uptake requires an energy source generated by respiration and glycolysis.

Anaerobiosis↗
PubMed1987

Studies on in vitro antipyrine metabolism by 13C,15N double labeled method.

The capacities of forms of cytochrome P-450 to oxidize antipyrine were compared. An isotope dilution gas chromatography/mass spectrometry/selected ion monitoring assay was developed to quantify the three main metabolites, norantipyrine, 3-hydroxymethylantipyrine and 4-hydroxyantipyrine. 13C,15N-Double labeled antipyrine was used as a substrate and the metabolites were analyzed as their trimethylsilyl derivatives. Among forms of cytochrome P-450 examined, a male-specific form of P-450, namely P-450-male, showed higher activity to form all the three metabolites. The other forms were responsible only for the formation of norantipyrine and 4-hydroxyantipyrine. The activities of liver microsomes from untreated male and female rats and rats treated with phenobarbital, 3-methylcholanthrene or polychlorinated biphenyl were expressed dependent on the activities of forms of cytochrome P-450 examined.

Animals↗