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Biomedical subjects

F Sato

Publications and source records attributed to F Sato.

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

Electron microscopic comparison of the terminals of two electrophysiologically distinct types of primary vestibular afferent fibers in the cat.

Two types of electrophysiologically distinct vestibular primary afferents (regular-type and irregular-type) were injected intraaxonally with HRP and their terminals were compared using the electron microscope. In general, regular-type terminals were small and two or more terminals contacted a single dendrite side by side, whereas irregular-type terminals were large and covered a wide surface of the dendrites. Both types of terminals contained spherical clear vesicles with almost the same diameter. Prominent postsynaptic membrane specializations were observed in both types. Mitochondria in both types had an elliptical profile with the same elongation index, but mitochondria in the regular-type terminals were thicker than those in the irregular-type ones.

Action Potentials↗
PubMed1988

Flagellar quiescence and transience of inactivation induced by rapid pH drop.

The effects of rapid pH drop on the flagellar movement of reactivated sea urchin sperm were studied by video microscopy and by a newly developed pH jump method. Triton-demembranated sperm were reactivated in a thin layer of the reactivation medium containing ATP and potassium acetate and supported by a ring-shaped Millipore filter stuck to the lower surface of a supported coverslip. The pH of the medium was lowered rapidly by dissolving acetic acid vapor abruptly introduced into a gap between the cover and slide. Flagellar beating ceased immediately when the pH of the reactivation medium was lowered. At least two types of cessation were distinguished: 1) "instantaneous" cessation in a bent form closely resembling those characteristic of steady-state beating before pH drop (waveform freeze), and 2) flagellar quiescence in a cane-shaped form resembling those characteristic of Ca-induced quiescence (cane-shaped quiescence). The flagellum again began beating if the pH was raised to normal but eventually was disintegrated by tubule sliding if the pH was left lowered. Field-by-field analysis of the transient movement of flagella becoming quiescent upon pH drop demonstrated that the proximal bend of the cane-shaped form corresponded to the principal bend of the steady-state beating in some flagella, but in others, to the reverse bend. These observations indicate that low pHs affect flagellar beating by interfering with sliding-bending conversion by a mechanism different from that previously reported.

Animals↗
PubMed1988

Selection of an atrazine-resistant tobacco cell line having a mutant psbA gene.

A mutant cell line that shows high resistance to the photosynthesis-inhibiting herbicide atrazine was selected from cultured photomixotrophic Nicotiana tabacum cv. Samsun NN cells by repeated exposure to toxic levels of the herbicide. This resistance was confirmed by measurements of Hill reaction activity in isolated thylakoid membranes. Nucleotide sequencing revealed that the resistant cell line had a point mutation in its chloroplast psbA gene. The 264th codon, AGT (serine) was changed to ACT (threonine) in this mutant. This new type of mutation also conferred moderate cross-resistance to diuron and subsequently was stable in the absence of continued selection pressure.

Amino Acid Sequence↗
PubMed1988

Passage of indigestible particles of various specific gravities in sheep and goats.

1. Eight kinds of indigestible particles with specific gravities (SG) ranging from 0.92 to 1.87 (2 mm diameter and 4 mm length) were injected into the reticulo-rumen of sheep and goats in order to investigate the relation between SG and passage through the gastrointestinal tract, and the difference in passage time in the two species of animals. 2. The percentage of excreted particles significantly increased, while the percentage of ruminated particles in the excreted particles significantly decreased, as the SG increased. 3. The daily and cumulative recovery rates of particles of SG 1.38 were slower in sheep than in goats, while those with SG 0.92 were not different between species. 4. It is concluded that particles with SG higher than 1.27 would pass through the gastrointestinal tract of sheep and goats more quickly than those with SG lower than 1.21.

Animals↗
PubMed1988

K+ efflux from the monkey eccrine secretory coil during the transient of stimulation with agonists.

1. Using a K+-sensitive extracellular electrode, we attempted to determine whether cholinergic stimulation of the simian palm eccrine sweat gland is associated with transient net K+ efflux as in other exocrine glands. 2. When isolated secretory coils placed in a glass capillary were continuously superfused (method A), 32% of total cellular K+ was lost during 3 min of stimulation with methacholine (MCh) followed by K+ reuptake when stimulation was stopped. 3. When secretory coils were stimulated in a small chamber (without continuous superfusion, method C), MCh (5 x 10(-6) M)-induced maximal K+ efflux as determined by the peak level of extracellular K+ concentrations was dose dependent, inhibited by atropine but not altered by a cholinesterase inhibitor, physostigmine (1.3 x 10(-5) M). Thus the peak K+ level was used as a measure of K+ efflux throughout the study. 4. Phenylephrine (10(-4) M) and A23187 (5 x 10(-6) M) also induced K+ efflux but to a lesser extent than did MCh. 5. Ouabain (10(-3) M)-induced K+ loss was 2.4-fold higher than the peak level of MCh-induced K+ efflux. 6. In a Ca2+-free medium with added EGTA, inhibition of K+ efflux was only partial in the first MCh stimulation but progressively increased on repeated stimulation, suggesting that cytoplasmic or membrane Ca2+ not readily accessible to EGTA may be important for K+ efflux. Inhibition of K+ efflux in the Ca2+-free medium was completely reversed on subsequent addition of Ca2+. 7. Five millimolar Ba2+ partially inhibited MCh-induced K+ efflux. 8. 10(-4) M-bumetanide itself caused a small K+ loss and strongly inhibited the subsequent MCh-induced K+ loss. 9. MCh-induced K+ loss was drastically inhibited in the low-Cl- (by replacing with gluconate- or methylsulphate-) or low-Na+ (by replacing with Tris+) medium. 10. K+ efflux occurs predominantly across the basolateral membrane. 11. Vinblastine at 10(-4) M, which completely inhibits sweat secretion (our unpublished results), however, showed no effect on MCh-induced K+ efflux. 12. We conclude that the transient net K+ efflux associated with MCh stimulation constitutes a crucial primary ionic event in cholinergic eccrine sweat secretion as in other exocrine secretory cells.

Animals↗
PubMed1988

Relationship between quin2-determined cytosolic [Ca2+] and sweat secretion.

Although both methacholine (MCh)- and A23187-induced sweat secretion are known to be strictly dependent on extracellular Ca2+, the role of intracellular calcium concentration ([Ca2+]i) in eccrine sweating has not been clarified. Partially purified eccrine secretory cells were prepared from 400 to 600 isolated secretory coils of monkey sweat glands by serial collagenase digestion and Percoll gradient centrifugation. The quin2 method was used for semiquantitative determination of [Ca2+]i, MCh increased [Ca2+]i in a dose-dependent, reversible, and pharmacologically specific manner (from the resting [Ca2+]i of 80-320 nM) but failed to increase [Ca2+]i in a Ca2+-free medium. A23187 (10(-7) M) increased [Ca2+]i to approximately 900 nM. Theophylline (TH), isoproterenol (ISO), and forskolin (FK) had no effect on the resting [Ca2+]i but, in combination, attenuated the effect of subsequently added MCh and A23187. A23187 at 10(-7) M failed to stimulate sweat secretion or CO2 production in vitro from the quin2-loaded intact isolated sweat glands and dispersed sweat secretory cells, respectively. The observed dissociation between the increase in [Ca2+] may suggest either that MCh stimulation induces some unknown excitatory signal in addition to a rise in [Ca2+] or that A23187-induced Ca2+ influx into the secretory cells is much lower in undissociated sweat glands.

Aminoquinolines↗
PubMed1988

Plasma atrial natriuretic peptide in states of altered thyroid function.

To examine a possible role of atrial natriuretic peptide (ANP) in water and electrolyte disturbances associated with thyroid disorders, plasma ANP levels were studied in patients with hyper- and hypothyroidism. In 5 of the 21 hyperthyroid patients, including two patients with atrial fibrillation and two patients with mild cardiomegaly, the plasma ANP concentration was increased when compared to normal subjects. After treatment with methimazole or propylthiouracil, the plasma ANP concentration fell to normal in 4 patients, while it remained high in one patient who had persistent atrial fibrillation. No significant correlation was found between plasma ANP and the heart rate in untreated hyperthyroid patients. Plasma ANP was within the normal range in all 8 patients with hypothyroidism. During treatment with T4, the plasma ANP concentration increased in 6 of the 7 patients. Chest X-ray films and ultrasonic echocardiography demonstrated pericardial effusion in 4 of these patients before therapy. A weak but significant correlation was found between the plasma ANP and T4 concentration, and between plasma ANP and free T4 in hyper- and hypothyroid patients before and after treatment. These results indicate that abnormalities in ANP dynamics in thyroid disorders may probably be caused by hemodynamic changes resulting from a thyroid hormone excess or deficiency.

Adolescent↗
PubMed1988

Mechanism of kinin release from human low-molecular-mass-kininogen by the synergistic action of human plasma kallikrein and leukocyte elastase.

We have investigated the kinin release from human L-kininogen, a poor substrate for plasma kallikrein, by the synergistic action of human PMN elastase and plasma kallikrein. Although PMN elastase alone failed to generate kinin activity from L-kininogen, combination of PMN elastase with plasma kallikrein was found to be effective for the generation of kinin activity from L-kininogen. Two kinds of kinin, bradykinin and Met-Lys-bradykinin, were found to be released from L-kininogen by the synergistic action of PMN elastase and plasma kallikrein. Pretreatment of L-kininogen with PMN elastase facilitated the kinin release by plasma kallikrein, whereas pretreatment of L-kininogen with plasma kallikrein did not allow kinin release by the action of PMN elastase. These results suggested that PMN elastase would act firstly on L-kininogen to form a kinin containing fragment, from which kinin is released by the action of plasma kallikrein. The kinin-containing fragment was isolated by gel filtration and high-performance liquid chromatography of the elastase digest of L-kininogen. The amino-acid analysis and N-terminal amino-acid sequence analysis revealed that the kinin-containing fragment consisted of 26 amino-acid residues and is formed by cleavage of an Ile-Ser and a Ser-His bond of L-kininogen.

Amino Acid Sequence↗
PubMed1988

Effects of plasma volume and osmolality on secretion of atrial natriuretic peptide and vasopressin in man.

To clarify the role of blood volume and osmolality in the mediation of the release of atrial natriuretic peptide (ANP) and to examine the relationship between plasma ANP and plasma AVP levels in man, the effects of hypertonic saline and hypertonic mannitol infusion, and of water load on plasma levels of ANP and AVP were studied. Infusion of 5% saline to 7 healthy men at a rate of 0.05 ml.min-1.kg-1 for 2 h resulted in a parallel rise in plasma sodium, osmolality, plasma ANP and plasma AVP, indicating that plasma hyperosmolality stimulates secretion of both ANP and AVP. Infusion of 20% mannitol to 6 healthy men at the same rate resulted in a parallel increase in plasma osmolality, plasma ANP and AVP, whereas plasma sodium decreased, indicating that plasma hyperosmolality stimulates secretion of both ANP and AVP. Water load (20 ml/kg) into 7 healthy men produced a prompt and parallel fall in plasma sodium, plasma osmolality and plasma AVP. In contrast, plasma ANP and plasma volume, calculated from the changes in hematocrit, increased concomitantly, which indicates that expanded plasma volume stimulates secretion of plasma ANP. These results suggest that secretion of ANP in man is regulated principally by plasma volume, which may be modulated by a change in plasma osmolality. AVP secretion, on the other hand, is controlled mainly by osmotic change and secondarily by plasma volume.

Adult↗
PubMed1988

ESR and spin-trapping study of free radicals in gamma-irradiated solid lysozyme.

Free radicals produced by gamma-irradiation of solid lysozyme were investigated by a technique combining ESR, spin-trapping and enzymatic digestion. MNP and DMPO were used as spin-trapping reagents. The solid lysozyme was first gamma-irradiated and then dissolved in an aqueous solution containing the spin-trapping reagent to stabilize free radicals. The spin adducts of lysozyme were digested to oligopeptides to get ESR spectra having a well-resolved hyperfine structure. The ESR spectra obtained showed that carbon-centered radicals, -CH-, at the side chains of amino acids, and thiyl radicals, -CH2-S., at disulfide bridges were produced in gamma-irradiated solid lysozyme.

Electron Spin Resonance Spectroscopy↗
PubMed1988

Metabolic effects of 3'-deoxyadenosine (cordycepin) and 2-halo-3'-deoxyadenosine on repair of X-ray-induced potentially lethal damage in Chinese hamster V79 cells.

Using cultured Chinese hamster V79 cells, an attempt has been made to examine the phosphorylation of cordycepin and its 2-halo derivatives (2-chloro-3'-deoxyadenosine, 2-bromo-3'-deoxyadenosine, and 2-iodo-3'-deoxyadenosine) by adenosine kinase, within the cells, and to correlate it with their cytotoxicities and abilities to inhibit the repair of X-ray-induced potentially lethal damage (PLDR). Of all compounds, only cordycepin was found to be phosphorylated and showed both potent cytotoxicity and ability to inhibit PLDR.

2-Chloroadenosine↗
PubMed1988

Variable reduction in beta-adrenergic sweat secretion in cystic fibrosis heterozygotes.

Because patients with cystic fibrosis (CF) consistently lack sweating response to isoproterenol (ISO) in vivo and in vitro, we studied to what extent beta-adrenergic defect is expressed in CF heterozygotes. To improve the sensitivity and accuracy of determining the sweating response to intradermal ISO (also containing theophylline and atropine), a water vapor analyzer was used, and the peak sweat rates attained after intradermal injection in the forearm of optimal concentrations of ISO and methacholine (MCH) were determined. The peak ISO sweat rate was further normalized by the peak MCH sweat rate in each individual and expressed as the relative ISO sweat ratemax (in percent). The relative ISO sweat ratemax was determined independent of age and sex and was unchanged after brief acclimatization. The mean relative ISO sweat ratemax of CF heterozygotes was significantly lower than that of controls (10.1% vs 19.5%); however, 21 of the 54 CF heterozygotes overlapped with controls, and the remainder of the CF heterozygotes fell below the arbitrary demarcation line drawn at the relative sweat rate of around 10%. Thus, although the ISO sweat test may not be a practical discrimination test for CF heterozygotes, knowledge of the diversity of beta-adrenergic sweating responses in CF heterozygotes will provide a useful data base for further understanding the possible linkage (or its absence) between the abnormal CF gene(s) (which may be identified by molecular biologists in the near future) and the abnormal intracellular process(es) that takes place during beta-adrenergic stimulation of the CF eccrine sweat gland.

Acclimatization↗
PubMed1988

["One-knot" microvascular anastomosis using glutide as an external splint--experimental arterio-arterial anastomosis in rats].

Experimental microvascular anastomosis using a glutide copolymer (lactide: glycolide = 80: 20) as an external splint was undertaken in rats between the left and the right carotid arteries. Both arteries were dissected free over a 1-cm length, the left carotid artery was transected at the cranial end, and the right carotid artery was cut at the caudal end. The left carotid artery was then introduced into a glutide pipe-splint. The arterial wall was turned back 180 degrees over the edge of the splint. The reflected part of the artery and the glutide were covered with the freed-up right carotid artery. One stitch was made around the two arteries and the glutide in a manner similar to that of binding a barrel with steel wire. The "One-knot anastomosis" was then complete. We call this type of anastomosis "antegrade anastomosis". If, on the other hand, the right carotid artery is introduced into the pipe, turned back at the edge of the glutide, covered with the left carotid artery and secured with one stitch, the technique is known as "retrograde anastomosis". The patency rates of the resulting vessels were as follows: antegrade anastomosis, 83% (15/18); and retrograde anastomosis, 92% (23/25); so that the average patency rate was 88% (38/43). We measured the anastomosing time that is the time between the transection of one of the two arteries and the completion of the anastomosis. The average anastomosing time was 21 minutes for antegrade anastomosis and 14 minutes for retrograde anastomosis. But the 'pure anastomosing time' (the time taken to connect the two already prepared arteries) was 2-3 minutes. We believe that one-knot anastomosis technique for future clinical application is promising.

Anastomosis, Surgical↗
PubMed1988

Clinical significance of immunoglobulin A antibody to hepatitis B core antigen of polymeric and monomeric forms in chronic type B liver disease with acute exacerbation.

Serum immunoglobulin A (IgA) hepatitis B core antibody (anti-HBc) was measured by a solid-phase enzyme immunoassay using monoclonal antibodies in sera from chronic carriers of hepatitis B surface antigen (HBsAg). To reinforce the clinical significance of IgA anti-HBc, levels of IgA subclasses and molecular characterization of IgA anti-HBc in sera of 13 patients in the acute exacerbation phase and the remission phase were compared. IgA anti-HBc was significantly higher in sera in the acute exacerbation phase than in the remission phase (p less than 0.025); in particular, more significant changes were observed in IgA2 anti-HBc (p less than 0.0025) and in secretory IgA anti-HBc (p less than 0.001). Analysis of molecular size distribution of IgA anti-HBc by high performance liquid chromatography showed that the elevation of polymeric IgA anti-HBc was significantly greater than that of monomeric IgA anti-HBc in the acute exacerbation phase (p less than 0.05), although there was an increase in both monomeric and polymeric IgA anti-HBc. Thus, the elevation of polymeric IgA anti-HBc suggests that the focal immune response against HBcAg in the liver and secretory IgA anti-HBc is an important marker of acute exacerbation in patients with HBsAg-positive chronic liver disease.

Carrier State↗