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Biomedical subjects

F Sato

Publications and source records attributed to F Sato.

At least 289 records · Page 16Linked to original sources
PubMed1990

Na+, K+, H+, Cl-, and Ca2+ concentrations in cystic fibrosis eccrine sweat in vivo and in vitro.

Sweat Na+, K+, H+, Cl-, Ca2+, and protein concentrations were reexamined with the use of three methods; namely, in vitro sweat induction from isolated single sweat glands, intradermal methacholine-induced sweating, and thermally induced sweating. [Na+] and [K+] in the primary sweat induced in vitro were nearly isotonic to the bath in both cystic fibrosis (CF) and control. In CF the [Na+] in both proximal ductal and skin surface sweat was always higher than 100 mmol/L. However, [Na+] never reached the isotonic level of 151 mmol/L, even at the highest sweat rate. Thus Na+ absorption never saturates, suggesting that the net NaCl absorption may increase with increasing sweat rate. pH of the primary sweat was 7.13 for CF and 7.29 for control, which corresponds to a [HCO3-] of 7.3 and 10.5 mmol/L, respectively. [Cl-] in the primary sweat was hypertonic (134 mmol/L for CF and 129 mmol/L for control) to the bath (118.4 mmol/L). In CF, ductal acidification of sweat occurred normally during intradermal methacholine-induced sweating, whereas ductal acidification of sweat was much higher in control than in CF in thermally induced sweating. [K+] in CF was higher in the skin surface sweat but not in the proximal duct sweat, suggesting that the predominant site of K+ secretion in CF may be in the distal duct. [K+] in the intradermal methacholine-induced sweat was much higher than that of thermally induced sweat in both CF and control samples. Free but not total [Ca2+] was also increased in CF skin surface sweat. The sweat protein concentration was the same in both CF and control samples. The mechanisms of the different electrolyte concentrations in CF sweat remain to be studied. However, the present observations will provide the basis for future studies on normal and abnormal regulation of membrane transport in CF sweat glands.

Adolescent↗
PubMed1989

Morphology of single primary vestibular afferents originating from the horizontal semicircular canal in the cat.

The central projections of physiologically characterized vestibular nerve fibers originating from the horizontal semicircular canal were studied in the vestibular nuclei of adult cats after intracellular staining with horseradish peroxidase (HRP). First, primary nerve fibers were physiologically classified as regular or irregular types on the basis of the regularity of the spontaneous discharge pattern. Then, these two types of fibers were morphologically analyzed and compared following HRP intraaxonal injection. The two types of axons showed a basically similar trajectory in the four major vestibular nuclei. They bifurcated into an ascending and a descending branch in the ventrolateral part of the lateral vestibular nucleus (LVN). The ascending branch extended rostrally and gave off one or two collaterals in the superior vestibular nucleus (SVN), although some of the ascending branches further ran rostrally into the cerebellum. The collaterals, while running medially, gave rise to fine terminal branches with en passant boutons in the SVN, and further coursing caudally, they entered the rostral part of the medial vestibular nucleus (MVN). The descending branch, while running caudally in the lateral part of the LVN and the inferior vestibular nucleus (IVN), gave off several thick collaterals to the MVN and extensive terminals were present in the IVN and MVN. In each primary axon, about one-third of the total terminal boutons were distributed in each of the SVN, the MVN, and the IVN. In contrast to this similarity of the overall axonal trajectory within the vestibular nuclei, both types of axons exhibited several marked differences in diameter and in the mode of terminal arborization. In almost every part of the ramification, the irregular-type fibers were thicker than the regular-type fibers. In the regular-type axons, many small terminal boutons (mean size, 2.4 x 1.4 microns, N = 2,739) were located in close proximity (100-150 microns) to the parent collateral. In the irregular-type axons, slightly larger terminal boutons (mean size, 3.0 x 1.7 microns, N = 1,287), were spread more widely (200-300 microns) around their collaterals. These clear morphological differences between the regular-type and the irregular-type terminal axons were consistently observed in any vestibular nucleus.

Animals↗
PubMed1989

Structure of 5-methoxy-2-([4-methoxy-3,5-dimethyl-2-pyridinyl) methyl]sulfinyl)-1H-benzimidazole (omeprazole).

C17H19N3O3S, Mr = 345.42, triclinic, P1, a = 10.686 (5), b = 10.608 (7), c = 9.666 (6) A, alpha = 119.75 (5), beta = 112.02 (5), gamma = 68.33 (4) degrees, V = 859 (1) A3, Z = 2, Dm = 1.332 (2), Dx = 1.335 g cm-3, Cu K alpha, lambda = 1.5418 A, mu = 18.04 cm-1, F(000) = 364, T = 293 K, R = 0.057 for 1962 observed reflections. The methylsulfinyl group, which adopts a trans conformation, links the pyridine and benzimidazole rings in an almost coplanar orientation. Thus the molecule, as a whole, adopts a nearly extended form. Two centrosymmetrically related molecules form a cyclic dimer by intermolecular N-H...O hydrogen bonding, and the dimers are held together by van der Waals contacts between the neighboring aromatic rings in the crystal structure.

Omeprazole↗
PubMed1989

Evidence for the formation of strand-break precursors in hydroxy-attacked thymidine 5'-monophosphate by the spin trapping method.

A method combining spin trapping, ESR, and HPLC was employed to obtain evidence for the formation of sugar radicals in OH-attacked TMP with special emphasis on the detection of strand-break precursors of DNA. OH radicals were produced by irradiating an N2O-saturated aqueous solution with X-rays. When an N2O-saturated aqueous solution containing TMP and a spin trapping reagent, MNP, was irradiated with X-rays, it was estimated on the basis of theoretical calculations using rate constants that 94% of the TMP radicals were induced by OH radicals. Since several spin adducts between TMP radicals and MNP, as well as the byproducts of the spin trapping reagent itself, were produced, reverse-phase HPLC was used to separate them. The presence of six spin adducts was confirmed by ESR examination. Further examination of these spin adducts by UV absorbance spectrophotometry showed the presence of a chromophore at 260 nm in three adducts. Since a gradual increase in the release of unaltered base from these adducts was observed when they were allowed to stand for 0-22 h at room temperature, they could be regarded as the spin adducts of sugar radicals and MNP. ESR spectra from the spin adducts were consistent with hydrogen abstraction radicals at the C1', C4', and C5' positions of the sugar moiety. These radicals appeared to be precursors of AP sites and strand breaks. In addition to these spin adducts, ESR spectra that were consistent with the spin adducts of base radicals (the C5 and C6 radicals) and MNP were observed.

Chromatography, High Pressure Liquid↗
PubMed1989

Morphological analysis of single astrocytes of the adult cat central nervous system visualized by HRP microinjection.

The morphology of individual astrocytes of the adult cat was analyzed by HRP microinjection and light microscopy. The astrocytes had generally two types of processes: (1) thread-like processes of relatively constant width with few ramifications and few lamellar appendages and (2) the sinuous processes with clusters of lamellar appendages. The former processes were morphologically characterized as follows: (1) Those of fibrous astrocytes were frequently remarkably long, ranging from 600 to 1500 microns. They were much longer than any astrocytic processes hitherto reported in the literature. In contrast, those of protoplasmic astrocytes were usually short (30-400 microns), and were sometimes decorated with lamellae. (2) The processes often terminated in endfeet on the subpial surface of the brain tissue or on blood vessel walls. The number of endfeet per cell varied from 1-11 with a tendency to split into two populations close to each extreme number. Another type of endfoot was also found, i.e. swellings along the trunk of the processes which made side-to-side contact with the vessel wall. The sinuous processes rich in lamellae were predominant in protoplasmic astrocytes, and clearly corresponded to the sheet- or veil-like processes of Golgi-impregnated astrocytes. They formed an ellipsoidal field (100 microns for the longer, and 50-60 microns for the shorter, diameter) around the nucleus.

Animals↗
PubMed1989

Induction of DNA double-strand breaks in Chinese hamster V79 cells by 2-chlorodeoxyadenosine.

2-Chlorodeoxyadenosine was found to induce DNA double-strand breaks as well as cell death in log-phase Chinese hamster V79 cells. The induction of DNA double-strand breaks, measured by a neutral elution technique, was observed after a 2-h incubation of the cells in the presence of 5 microM of 2-chlorodeoxyadenosine, but these breaks were almost rejoined by a subsequent 1-h incubation, even though this drug was present in the medium during incubation. This repair was prevented by the addition of nicotinamide, which is known to inhibit poly(ADP-ribose) synthesis that is strongly associated with the DNA ligation, but not prevented by the addition of 9-beta-D-arabinofuranosyladenine (araA), which is known to inhibit DNA polymerization. These results suggest that the repair of CdA-induced double-strand breaks is achieved by ligation alone without DNA polymerization. When 35 microM of cycloheximide and 1.3 mM of dibutyryl cAMP were added to the medium, it was found that the induction of double-strand breaks by 2-chlorodeoxyadenosine was suppressed, while the cytotoxicity of 2-chlorodeoxyadenosine measured by colony-forming ability was not interfered with. These results suggest that the induction of DNA double-strand breaks is not associated with the cytotoxicity of this drug.

2-Chloroadenosine↗
PubMed1989

OH-induced free radicals in purine nucleoside monophosphates: e.s.r. and spin-trapping.

Free radicals produced by the reactions of OH radicals with six purine nucleoside monophosphates (3'-AMP, 5'-AMP, 5'-dAMP, 3'-GMP, 5'-GMP and 5'-dGMP) were investigated by a method combining e.s.r. spin-trapping and high-performance liquid chromatography (HPLC). The N2O-saturated aqueous solutions of purine nucleoside monophosphates, containing 2-methyl-2-nitrosopropane as a spin-trap, were X-irradiated and the resulting spin-adducts were separated by reverse-phase HPLC in the ion suppression mode. The separated spin-adducts were characterized by e.s.r. spectrometry and UV spectrophotometry. Consequently, the radicals due to H-abstraction at the C4' position of the sugar moiety were identified arising from 5'-dAMP and 5'-dGMP. In all cases, e.s.r. spectra consisting of a secondary doublet were observed and assigned to the radical due to H-abstraction at the C5' position of the sugar moiety.

Chromatography, High Pressure Liquid↗
PubMed1989

The mechanism of herbicide resistance in tobacco cells with a new mutation in the q(b) protein.

A new mutant of the psbA gene conferring resistance to 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) was obtained by selection of photomixotrophic tobacco (Nicotiana tabacum cv Samsun NN) cells. The 264th codon AGT (serine) in the wild psbA gene was changed to ACT (threonine) in these mutant tobacco cells. All other higher plants resistant to atrazine exhibit a change to GGT (glycine) in this codon. Measurements of Hill reaction activity and chlorophyll fluorescence showed that the threonine 264-containing plastoquinone serving as secondary stable electron acceptor of PSII (Q(B) protein) had not only strong resistance to triazine-type herbicides but also moderate resistance to substituted urea-type herbicides. Threonine-type Q(B) protein showed especially strong resistance to methoxylamino derivatives of the substituted urea herbicides. The projected secondary structures of the mutant Q(B) proteins indicate that the cross-resistance of threonine 264 Q(B) protein to triazine and urea herbicides is mainly due to a conformational change of the binding site for the herbicides. However, the glycine 264 Q(B) protein is resistant to only triazine herbicides because of the absence of an hydroxyl group and not because of a conformational change.

Journal Article↗
PubMed1989

Cytotoxic effect of acyclovir on cultured mammalian cells to which herpesvirus thymidine kinase gene was introduced.

The cytotoxic effects of acyclovir, which is a purine nucleoside analogue and is known as an antibiotic substance, were examined on three lines of rat skin fibroblast FR cells; normal FR cells, FRtk- cells which are deficient in the activity of thymidine kinase (tk) and FRtk-HSVtk+ cells which were prepared by introducing herpes simplex virus' tk gene to FRtk- cells. When FRtk-HSVtk+ cells growing exponentially were incubated in the presence of acyclovir for 4 h, the surviving fractions of the cells decreased in a concentration-dependent manner. Whereas, decrease of the surviving fractions was almost indiscernible in both FR cells and FRtk- cells at the whole ranges of drug-concentrations tested. These results indicate that acyclovir is phosphorylated by the herpes simplex virus' tk and becomes toxic to FRtk-HSVtk+ cells. This also means that FRtk-HSVtk+ cells are useful for the investigation of the biological activity of nucleoside analogues.

Acyclovir↗
PubMed1989

[Efficacy of home exercise program in a convalescent phase of acute myocardial infarction evaluated by Borg's indices, expiratory gas analysis and blood lactate].

The Borg's indices, the rate of perceived exertion have been widely accepted to evaluate subjective symptoms semi-quantitatively in exercise tests. We applied the indices to evaluate the efficacy of our home exercise program in patients with acute myocardial infarction. Eighty-five patients were entered in our home exercise program after their discharge from the hospital. This program consisted of everyday 2 km walk-jog exercise for 1 month keeping their heart rate at 100-110/min during the exercise. Before and 1 month after their discharge, they underwent treadmill exercise tests with expiratory gas analysis and a measurement of blood lactate. In the treadmill tests performed before and after the training, VO2 and heart rate increased linearly with Borg's indices, however VE and blood lactate had disproportionate increases after Borg's 13 which is considered to be the anaerobic threshold (AT). In fact, AT measured individually by expiratory gas analysis and blood lactate, appeared at Borg's 13 in 53% of the patients. After 1 month physical training, VO2 and heart rate significantly increased at the same Borg's indices, but there was no significant changes in blood lactate at the same Borg's score before and after the training. These results suggest that, in patients with acute myocardial infarction, exercise performance significantly increased at any score of subjective symptoms and that Borg's indices may reflect the blood lactate levels. It is concluded that Borg's indices, closely related to the dynamics of blood lactate, are not only useful in quantifying subjective symptoms but also to estimate the efficacy of physical training.

Adult↗
PubMed1989

Micronucleus test in mice fed on an irradiated diet.

A mutagenicity study was carried out in mice fed on a gamma-irradiated diet. As an indicator of mutagenic activity, we observed an incidence of micronuclei in erythrocytes. The average body weight of the mice fed on the diet irradiated to dose range of 400-1,000 kGy decreased, and the mice fed on the 800-1,000 kGy-irradiated diet died during the period from 8 to 14 days after the start of feeding. On the other hand, when the mutagenic activity of the irradiated diet was tested by observing occurrence of micronucleus in erythrocytes, no significant increase was recognized. These results indicated that the irradiated diet had no mutagenic activity, even though it possessed a toxic effect on the growth of mice.

Animals↗
PubMed1988

Charge-dependent regulation of NADPH oxidase activities in intact and subcellular systems of polymorphonuclear leukocytes.

It has been reported that respiratory bursts with N-formylmethionylleucylphenylalanine, A23187, phorbol ester and fatty acids are switched off and on by modulating the net charges of plasma membranes in guinea-pig neutrophils (Miyahara, M. et al. (1987), Biochim. Biophys. Acta, 929, 253-262). In the present study, this was further extended in cells treated with protein kinase C inhibitors which completely suppressed the phorbol ester-dependent respiratory burst. This suggested that the initiation of the respiratory burst, which is generally accepted as linked to protein kinase C activation, might also be implicated in the net charge changes of plasma membranes. The above results were also supported by data obtained with a cell-free system reconstituted with plasma membranes and cytosolic fractions from unstimulated neutrophils, guanosine 5'-[gamma-thio]triphosphate and NADPH. Arachidonate stimulated NADPH oxidase activity accompanied by a marked phosphorylation of membrane proteins. The phosphorylation was sensitive to H-7, but it did not appear to be essential for the respiratory burst, because the oxidase activation was insensitive to H-7. Pretreating the plasma membranes with positively charged cetylamine inhibited the oxidase activation by arachidonate. These results suggest that a charge-dependent process, which does not use protein kinase C, may play an important role in the reaction leading to NADPH oxidase activation, and this may be related to the interaction of plasma membranes with the cytosolic activation factor.

Animals↗