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Biomedical subjects

S Fujii

Publications and source records attributed to S Fujii.

At least 883 records · Page 49Linked to original sources
PubMed1981

Synthesis and molecular conformation of 2',3'-O-isopropylidene-5'-deoxy-6(R),5'-cyclo-5,6-dihydrouridine.

The title compound (hereafter abbreviated as 6(R),5'-cyclo-hUrd) is synthesized from 2',3'-O-isopropylidene-5'-deoxy-5'-iodouridine and its molecular structure has been determined by X-ray analysis. 6(R),5'-Cyclo-hUrd crystallizes in space group C2 with Z = 4, and unit-cell dimensions a = 11.220 (2), b = 6.393 (1), c = 18,963 (3) A and beta = 107.98 (1) degrees. The structure was solved by direct interpretation of the three-dimensional Patterson function and refined to a final R index of 0.063. In the crystal the glycosyl torsion angle chi CN is 60.7 degrees (anti conformation) and the dihydrouracil ring adopts a half-chair conformation. The puckering of the ribose ring is an unusual O(1')-exo (P = 267 degrees, tau m = 47 degrees). The coupling constants of the 1H-NMR spectrum measured in C2HCl3 solution indicate that the overall conformation of 6(R),5'-cyclo-hUrd found in crystal is also maintained in solution. The theoretical calculations of coupling constants by the finite perturbation theory (FPT) intermediate neglect of differential overlap, self-consistent field molecular orbital (INDO SCF-MO) method indicate that the deviation of the observed coupling constants of sugar ring protons from those predicted by applying modified Karplus-type formula to the X-ray structure could be due to the strains around the sugar ring carbon atoms attached by protons.

Chemical Phenomena↗
PubMed1981

Purification and properties of thiol protease inhibitor from rat liver cytosol.

Thiol protease inhibitors were found in the cytosol fractions of various rat tissues. An inhibitor, named cytosol thiol protease inhibitor, was purified from rat liver cytosol by acid treatment and column chromatographies on Sephadex G-50, DEAE-Sephadex and Sephadex G-75. The purified inhibitor gave a single protein band on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The molecular weight of the inhibitor was found to be 12 400 by gel filtration on Sephadex G-75 and SDS-polyacrylamide gel electrophoresis, and its isoelectric point was found to be 5.04. This inhibitor inhibited rat liver lysosomal cathepsin B, B2, C, H and L and papain, but not cathepsin A or D, trypsin or chymotrypsin. The inhibitor caused noncompetitive inhibition of the hydrolytic activity of cathepsin H on alpha-N-benzoyl-DL-arginine 2-naphthylamide and its Ki value was 4.08 . 10(-8) M. Heat treatment at 80 degrees C for 10 min reduced the activity 40%.

Animals↗
PubMed1981

Localization of pacemaking activity in early embryonic heart monitored using voltage-sensitive dye.

Early in cardiogenesis, heart primordia are brought together at the midline and fuse with each other progressively caudally-- this results in the formation of the primitive tubular heart which begins beating spontaneously at the middle period of the 9-somite developmental stage in the chick embryo. However, in these very early stages of development, the myocardial cells are small and technically difficult to impale with microelectrodes; thus electrophysiological studies on the very early embryonic heart are rare. Recently, potential sensitive dye-related absorption signals have provided a new method for monitoring spontaneous action potential activity in the early embryonic heart. This technique is based on the observation that changes in potential across membrane(s) stained with certain voltage-sensitive dyes are accompanied by changes in their optical properties (absorption, fluorescence, and/or birefringence). Using absorption signals, we have already demonstrated in embryonic pre-beating chick heart in the 7-8-somite stages, the occurrence of action potential activity, development of pacemaker potential and cardiac rhythm generation. With this method, originally introduced to record neuronal activity in invertebrate ganglia, many cells or portions of the preparation can be monitored simultaneously. Accordingly we have expanded the optical recording apparatus to monitor simultaneously spontaneous action potentials from five portions of an early embryonic heart, and report here experiments carried out on the embryonic hearts of chicks (white Leghorn) at the 7-11-somite developmental stages, corresponding to 25-35 h of incubation. The hearts attached to the embryo were stained with a merocyanine-rhodamine dye (NK2761) as a potentiometric probe. This dye is analogue of Dye XVII or Dye XXIII.

Action Potentials↗
PubMed1981

Gel filtration profile of plasma active and inactive renin in normals and patients with nephrotic syndrome.

The molecular weight of plasma renin from healthy subjects and patients with nephrotic syndrome, in whom we previously reported that plasma inactive renin was increased, was studied by gel filtration. Activation was performed by acid treatment. The plasma from healthy subjects contains a low molecular weight from of renin (40 000) and a high molecular weight form which can be separated into two peaks of 52 000 and 60 000. After acid activation, renin activity was increased in the high molecular form but not significantly in the low molecular form. Although the increase of renin activity in the high molecular weight form after acid activation was larger in patients with nephrotic syndrome, the gel filtration profile was similar to that of healthy subjects.

Chromatography, Gel↗
PubMed1981

Proton magnetic resonance study of Streptomyces subtilisin inhibitor. pH titration and assignments of individual tyrosyl resonances.

This paper reports the pH titration at 25 degrees C and the assignment of aromatic proton resonances of three tyrosyl residues of each identical subunit of Streptomyces subtilisin inhibitor (Mr 23000) by high-resolution 1H NMR spectroscopy. The complete assignments of the specific tyrosyl resonances were made based on the results of the differential chemical modification of the tyrosyl residues with tetranitromethane followed by peptide analysis, independently of the knowledge of the crystal structure. pKa values of Tyr-7, -75, and -93 were determined in a 2H2O solution to be 10.95, 11.8, and greater than or equal to 12.6, respectively, at 25 degrees C, whereas pKa values of nitrated Tyr-7 and -75 were determined to be 7.3 and 7.9, respectively. Tyr-93 was not nitratable under normal conditions. The strong resistance to nitration, together with the extremely high pKa value and the high-field shifted positions of the ring proton resonances of Tyr-93 at neutral pH, strongly suggests that Tyr-93 takes part in a hydrogen bonding as a proton donor. Tyr-7 is more easily modified with tetranitromethane than Tyr-75, although in the crystal Tyr-75 is more exposed than Tyr-7. The result, together with the pKa value of Tyr-75 significantly higher than that of a normal tyrosine, indicates that the microenvironment of Tyr-75 is more restricted in solution than in solid. These results imply that structural details of a protein may be quite similar in solution to those in the crystal in the rigid hydrophobic region of the protein but that in the surface region of the protein local structures may well differ between the solution and the crystal.

Amino Acids↗
PubMed1981

Progesterone-induced smooth muscle-like cells in the subperitoneal nodules produced by estrogen. Experimental approach to leiomyomatosis peritonealis disseminata.

In order to examine the pathogenesis and histogenesis of leiomyomatosis peritonealis disseminata (LPD), guinea pigs were treated with various doses of estradiol benzoate (E) (40, 80, 100, and 200 microgram/day, three times a week, by intramuscular injection). After treatment for 3 months, each dose of E produced lesions simulating the disseminated pattern of LPD. Ultrastructurally, the nodules were considered to be composed of cells resembling those of fibroblast. In guinea pigs, pretreatment with estradiol benzoate (100 microgram/day, three times a week intramuscularly for 3 months followed by combination treatment with E and progesterone (P) (0.5 and 1.0 mg/day, once a week, intramuscularly) for 1 to 3 months produced nodules similar to those with estrogen alone. Ultrastructurally, these nodules were composed of cells resembling smooth muscle and decidual cells. According to these results, we conjectured that estrogen differentiates and proliferates cells with the features of fibroblast-like cells from the subcoelomic totipotential mesenchyme, and these cells are differentiated into smooth muscle-like cells and decidua-like cells under the influence of both estrogen and progesterone, resulting in the production of multiple subperitoneal nodules.

Abdominal Neoplasms↗
PubMed1981

Serum apoprotein A-I and A-II levels in liver diseases and cholestasis.

Serum apoprotein A-I and A-II levels were determined by electroimmunoassay in patients with liver diseases and cholestasis. Significant decreases in apoprotein A-I and A-II levels were observed in such patients. The decreases were especially pronounced in the early phase of acute hepatitis and cholestasis. The decreases in A-II levels were more prominent than the decreases in A-I in severe hepatic dysfunction or cholestasis. Accordingly, the A-I/A-II ratio showed no change in the convalescent phase of acute hepatitis or chronic hepatitis but increased significantly in the early phase of acute hepatitis, cirrhosis of the liver, hepatoma, and cholestasis. The results suggested the existence of a high density lipoprotein with an abnormal apoprotein composition or a more profound decrease of HDL3 than of HDL2 in severe hepatocellular dysfunction of cholestasis.

Adult↗
PubMed1981

The role of bovine high-molecular-weight (HMW) kininogen in contact-mediated activation of bovine factor XII: interaction of HMW kininogen with kaolin and plasma prekallikrein.

Previous studies from our laboratories (Sugo et al. (1980) Biochemistry 19, 3215-3220) have shown that bovine high-molecular-weight (HMW) kininogen remarkably accelerates the kaolin-mediated activation of Factor XII in the presence of prekallikrein, and that both fragment 1.2 and the light chain regions located in the COOH terminal half of the kininogen molecule are essential for the activation. In the present study, we demonstrate that the accelerating effect of HMW kininogen is mediated through its adsorption on the kaolin surface through the fragment 1.2 region and its complex formation with prekallikrein through the light chain region. The evidence is as follows: 1. HMW kininogen radio-labeled with 125I was adsorbed on kaolin and the adsorption was inhibited by the prior treatment of kaolin with fragment 1.2, fragment 1.2-light chain, kinin-free protein or HMW kininogen, but not with kinin- and fragment 1.2-free protein, light chain or low molecular-weight (LMW) kininogen. 2. The complex formation of HMW kininogen with prekallikrein in bovine plasma or in the purified system was examined by gel-filtration on a column of Sephacryl S-200 In bovine plasma, prekallikrein was eluted in the same fraction as HMW kininogen, showing an apparent molecular weight of 250,000, whereas purified prekallikrein was eluted in the fraction corresponding to an apparent molecular weight of 100,000. When purified prekallikrein was mixed with purified HMW kininogen in a mol ratio of 1 to 2, all prekallikrein was found to be associated with HMW kininogen. Furthermore, purified prekallikrein mixed with kininogen derivatives, such as kinin- and fragment 1.2-free protein, fragment 1.2-light chain or light chain, was eluted in the higher molecular weight fraction. HMW kininogen did not form a complex with prekallikrein. Using the same technique, it was shown that kinin- and fragment 1.2-free protein forms a complex not only with prekallikrein but also with kallikrein.

Adsorption↗
PubMed1981

Exposure of aromatic residues of Streptomyces subtilisin inhibitor. A photo-CIDNP study.

Exposure of aromatic residues, Tyr 7, Tyr 75, Tyr 93, His 43, His 106, and Trp 8, was studied by laser-induced photo-CIDNP in the 1H NMR spectrum of Streptomyces subtilisin inhibitor at 360 MHz. Only Tyr 7 and Tyr 75 gave strong CIDNP signals, whereas the rest of the aromatic residues gave no detectable signals in the temperature range 25-55 degrees C. From the temperature dependence data, it is concluded that Tyr 7 is well exposed at all temperatures, whereas the exposure of Tyr 75 increases with temperature, in agreement with the conclusion obtained by other methods. Agreements and discrepancies between the conclusions derived from the CIDNP data and the results so far obtained by other methods are compared for all the aforementioned aromatic residues.

Bacterial Proteins↗
PubMed1981

Optical recording of development of electrical activity in embryonic chick heart during early phases of cardiogenesis.

1. Developmental changes in the spontaneous action potential were measured using optical signals from early embryonic chick heart stained with a potential sensitive merocyanine-rhodanine dye. 2. The wave-length dependence of the dye signal is triphasic in early embryonic chick heart with a decrease in absorption from 525 to 600 nm, an increase from 625 to 720 nm, and a decrease at 750 nm. The signal was largest at 700 nm. 3. The magnitude of the spontaneous absorption signal increased as the development of the embryonic heart proceeded. In addition, the magnitude of the absorption signal differed among the various regions of an early embryonic chick heart and the number of electrically active cells increased dramatically throughout the 7-9 somite developmental stages. 4. The number of the electrically active cells was largest in the right portion of the ventricle at the 7-9 somite developmental stages. 5. The shape of spontaneous absorption signals could be classified into four types in the developmental stages between 7 and 9 somites: Signals resembling the cardiac action potential and the pace-maker potential were not recorded until the 8-9 somite developmental stage.

Absorption↗
PubMed1981

Optical indications of pace-maker potential and rhythm generation in early embryonic chick heart.

1. Pace-maker type action potentials and rhythm generation in very early embryonic chick hearts have been monitored using a voltage-sensitive merocyanine-rhodanine dye. 2. Rhythmicity in recurrence of the spontaneous action potentials was evident at the 7 somite developmental stage, and the rhythm was completely organized by the early period of the 9 somite stage; just before the first contraction. The rhythmic recurrence of action potentials was increased in frequency as development proceeded from the 7 to the 9 somite stage, and presumably gives rise to the rhythm of the initial contractions. 3. Optical signals resembling the pace-maker type action potential with a diastolic depolarization phase were first detected in embryonic hearts at the 8 somite stage. At this stage, pace-maker type action potentials were detected from various regions, such as the ventricle and the unfused primordia at the atrium level. 4. Regionalization of pace-maker type action signals was exhibited at the early period of the 9 somite stage. At this stage, the pace-maker type signals were often evident at the atrium level, while the cardiac type signals were detected in the ventricular region. 5. Hence it is concluded (i) that the rhythmicity has already been generated at the 7 somite developmental stage, (ii) that the pace-making cells are widely distributed in the embryonic hearts at the 7-8 somite stages and (iii) that the appearance of the pace-maker potential is initially localized to the atrium level at about the 9-10 somite stages.

Action Potentials↗
PubMed1981

Action potential synchrony in embryonic precontractile chick heart: optical monitoring with potentiometric dyes.

1. Using an optical method for monitoring membrane potential, we recorded spontaneous action potentials simultaneously in several different areas of the 7-9 somite embryonic chick hearts. 2. Absorption signals resembling spontaneous action potentials were well synchronized among the different areas in the prebeating embryonic heart during the 7-9 somite stages of development, and the synchronization spread over the entire area of the heart. From these experimental results, it is evident that there is electrical coupling among embryonic chick heart cells even in the early stages of cardiogenesis. 3. When an embryonic heart was separated into right and left or anterior and posterior parts, the action potential synchrony between the two halves was completely blocked; however, the synchrony and the intrinsic rhythmicity in action potential recurrence remained in each part.

Action Potentials↗
PubMed1981

Further investigations on the binding of loop diuretics to serum proteins from patients with liver disease.

The binding of three loop diuretics, piretanide, bumetanide and furosemide, to serum proteins from patients with liver cirrhosis or fulminant hepatitis was investigated using equilibrium dialysis. A good correlation was found between serum albumin concentration and the percentage of each unbound (free) loop diuretic in patients with liver disease. The binding data obtained from patients with liver cirrhosis was compared with that of patients with chronic renal failure. Calculations made according to the Sandberg-Rosenthal's formula revealed that the maximum binding concentration (nP) varied in some cases. These findings necessitated a detailed investigation into whether the increased percentage of each unbound loop diuretic in patients with liver disease is attributable not only to lowered serum albumin concentration but also to inhibition of the protein binding by some endogenous substances. Thus, similar experiments were performed using rats with experimental liver cirrhosis. The binding of the loop diuretics to serum proteins in cirrhotic rats differed greatly from the findings obtained from cirrhotic patients. The percentage of unbound loop diuretic was well correlated with serum albumin concentration but not with the concentration of serum bilirubin (an endogenous substance) in cirrhotic rats.

Adult↗
PubMed1981

Optical recording of conducted action potential in heart muscle using a voltage-sensitive dye.

The absorption signals of a merocyanine-rhodanine dye in response to action potential were measured on the bullfrog atrium. Simultaneous recording of optical signals and membrane potential showed the same time course within 15 to 30 min after exposure to Ca2+- free solution. The action spectrum of the dye exhibited a triphasic pattern with a decrease in absorption between 530 and 600 nm, an increase between 640 and 720 nm and a decrease at 750 nm. Using five photodetectors we have able to simultaneously monitor the action potential from five different regions of the preparation. The conduction velocity could be measured even in Ca2+- free solution; the velocity measured optically by the simultaneous multi-recording method was equal to that obtained with a microelectrode measurement. Thus, the optical method can validly be used to solve some problems on arrhythmia-related mechanism.

Action Potentials↗
PubMed1981

Metabolism of 5-fluorouracil in various human normal and tumor tissues.

The metabolism of 5-fluorouracil (5-FU) in tumors and normal tissues of humans was investigated in vitro. Phosphorylation of 5-FU was faster in tumor tissues than in normal tissues. Phosphorylating activity with 2-deoxy-alpha-D-ribose 1-phosphate (dRiblP) and ATP as cofactors was more active than that with alpha D-ribose 1-phosphate (RiblP) and ATP, or 5-phospho-alpha-D-ribosyldiphosphate (PPRibP) as cofactors. Phosphorylating activity in squamous cell carcinoma of the lung was similar to that in adenocarcinomas. Degradation of 5-FU was much faster in the liver than in other tissues including tumor tissues.

Adenocarcinoma↗
PubMed1981

Metabolism of pyrimidine nucleotides in various tissues and tumor cells from rodents.

The metabolism of pyrimidine nucleotides in various tissues and tumor cells of rodents was investigated. Ribonucleoside diphosphate reductase, thymidine monophosphate kinase and DNA polymerase (alpha, beta) were specifically localized in tumor cells, i.e., the activities of these enzymes in tumor cells were at least three times higher than those in normal tissues, including rapidly growing tissues, such as bone marrow, thymus, and spleen. The activities of deoxycytidine monophosphate deaminase and all the nucleoside kinase were high not only in tumor cells, but also in rapidly growing normal tissues, so that these enzymes are unsuitable as targets for cancer chemotherapy. The tissue distribution of other enzymes, including orotate phosphoribosyltransferases, cytidine triphosphate synthetase, thymidine monophosphate synthase, nucleoside phosphorylases and cytidine deaminase had no relation with the cell growth rate. AH130 tumor cells and the thymus showed specific increases in the activities of enzymes involved in de novo DNA synthesis. In contrast, Yoshida sarcoma and bone marrow showed high activities of enzymes in the salvage pathway of DNA synthesis, which suggested that the two tumors have different patterns of nucleotide metabolism.

Animals↗