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Biomedical subjects

M Hoshi

Publications and source records attributed to M Hoshi.

At least 235 records · Page 13Linked to original sources
PubMed1990

Glucosylceramide having a novel tri-unsaturated long-chain base from the spermatozoa of the starfish, Asterias amurensis.

Glucosylceramide (Glc beta 1-1Cer) was isolated from the spermatozoa of the starfish, Asterias amurensis. The long-chain bases of the glycolipid consisted of dihydroxy (d18:2, d18:3, d19:3, and d22:2), and trihydroxy (t22:1) types. Long-chain aldehydes derived from them were analyzed mainly by proton nuclear-magnetic resonance to determine the detailed structures. Two of the tri-unsaturated bases were identified as (4E,8E,10E)-2-amino-4,8,10-octadecatriene-1,3-di ol (d18:3) and (4E,8E,10E)-2-amino-9-methyl-4,8,10-octadecatriene+ ++-1,3-diol (d19:3), which is a novel base. Both d22:2 and t22:1 had a cis double bond at the C9 or C13 position. All fatty acids were 2-hydroxylated (C14-C25): Most of them were saturated and unbranched. About 10% was mono-unsaturated and unbranched (C22-C25), while saturated but branched (iso- and anteiso-types) C15-C18 acids were found as minor components. The main fatty acids, which summed up to more than 93% of the fatty acids in the glucosylceramide, were n-14h:0, n-15h:0, n-16h:0, n-17h:0, n-18h:0, and n-24h:1.

Aldehydes↗
PubMed1990

Gangliosides from the eggs of the sea urchin, Anthocidaris crassispina.

NeuGc alpha 2-6Glc beta 1-1Cer (M5 ganglioside) and HSO3-8NeuGc alpha 2-6Glc beta 1-1Cer (T1 ganglioside) were purified by column chromatographies with DEAE-Sephadex A-25 and silicic acid from the eggs of the sea urchin, Anthocidaris crassispina. Their chemical structures were determined by gas-liquid chromatography, methylation analysis, enzymatic hydrolysis, negative-ion fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance spectroscopy. Long-chain base compositions of both gangliosides were almost identical: all the long-chain bases were phytosphingosines, and C18-phytosphingosine accounted for more than 95% of them. Fatty acid compositions were also very similar: the main fatty acids were 22:1, 23:1, 24:1, and their 2-hydroxylated forms, and the 2-hydroxy fatty acids amounted to 65.3 and 74.3% of the fatty acids in M5 and T1 gangliosides, respectively. Proton nuclear magnetic resonance spectroscopic study revealed a downfield-shifted H8 proton signal of NeuGc residue in T1 ganglioside, in agreement with the presence of sulfate ester at the C8 position.

Animals↗
PubMed1990

Immunocytochemical study of the distribution of a ganglioside in sea urchin eggs.

An antibody against M5 ganglioside (NeuGc alpha 2-6Glc beta 1-1Cer), the dominant ganglioside in the eggs of the sea urchin, Anthocidaris crassispina, was purified by affinity chromatography from rabbit antiserum against crude ganglioside of the eggs. The specificity of the antibody was verified by enzyme-linked immunosorbent assay and TLC immunostaining. M5 ganglioside was also the major one in the eggs of another sea urchin, Hemicentrotus pulcherrimus, as judged from TLC analyses including immunostaining. Cryostat-sections of H. pulcherrimus eggs were examined to determine the distribution of M5 ganglioside by indirect immunofluorescence microscopy with the antibody. Before fertilization, the egg cortex was highly stained, while the other part of cytoplasm was uniformly but much more weakly stained. After fertilization, the staining rapidly decreased in the cortex and was restricted to a very thin peripheral layer and to cytoplasmic patches. The immunoreactivity was also observed in the esophagus and the somatic cells of the testis, but the spermatozoa were never stained with the antibody.

Animals↗
PubMed1990

Ceramide dihexosides from the spermatozoa of the starfish, Asterias amurensis, consist of gentiobiosyl- cellobiosyl-, and lactosylceramide.

Ceramide dihexoside was obtained from the spermatozoa of the starfish, Asterias amurensis. Gas-liquid chromatography of the methanolysate to determine the sugar composition of the lipid demonstrated an unequal ratio of glucose and galactose, implying that two or more glycolipids are present. They were separated by thin-layer chromatography on a borate-impregnated plate into two bands. From the results of methylation analysis and chromic acid oxidation, one was determined to be lactosylceramide, while the other was suggested to be a mixture of two diglucosylceramides: gentiobiosylceramide (Glc beta 1-6Glc beta 1-1Cer) and cellobiosylceramide (Glc beta 1-4Glc beta 1-1Cer). The molar ratio of gentiobiosyl-, cellobiosyl-, and lactosylceramide was estimated to be 0.7 : 0.3 : 1.0. Ceramide dihexosides obtained from another batch of the spermatozoa, collected at the same place in a different year, consisted almost exclusively of gentiobiosylceramide as confirmed by proton-nuclear magnetic resonance spectroscopy and fast-atom bombardment mass-spectrometry. The fatty acid compositions of these glycolipids were similar and the main acids were 14h:0, 15h:0, 16h:0, 18h:0, and 24h:1 (constituting more than 80% of the total acids). The long-chain base compositions were qualitatively similar and the major constituents were commonly d18:2, d18:3, d19:3, d22:2, and t22:1. Lactosylceramide was rich in t22:1, while diglucosylceramides were rich in d22:2.

Animals↗
PubMed1990

[Changes in the ions and protein concentrations and flow rate of parotid saliva by tongue sour stimulation].

Changes in the concentrations of ions (K+, Cl-, Na+), total protein, amylase activity and flow rate of parotid saliva were observed by tongue stimulation with 3% tartaric acid various intervals in a subject after about one hour rest. The results may be summarized as follows: 1) After about one hour rest state, the values of each item were K+: 42-56 mEq/l, Cl-: 8-28 mEq/l, Na+: 1-10 mEq/l, total protein: 5.7-11 mg/ml, amylase activity: 2-6.5 x 10(3)U/ml and flow rate: 0.03-0.05 ml/min. 2) The changes were classified into two groups based on the recovery from peak to rest values. One group showed short recovery times (Cl-: 20 min., Na+: 8 min. and flow rate: 2 min.) and the other group had rather longer recovery times (K+: 40 min., total protein: 55 min. and amylase activity: 40 min.). The differences between these two groups were clear when the stimulus intervals were 30 sec. to 5 min. 3) When the tongue was stimulated every 15 sec. all items showed first responses, after that, the all values except the flow rate remained unchanged. 4) Different values in ions and protein concentrations and amylase activity were observed when the flow rate was similar before and after stimulation. 5) The recovery time of the responses of protein concentration and amylase activity to stimulation was about one hour, and a rest period of more than one hour is necessary to analyze the concentration of total protein and amylase activity in parotid saliva.

Amylases↗
PubMed1990

Egg signals for triggering the acrosome reaction in starfish spermatozoa.

Upon encountering the jelly coat of an egg, starfish spermatozoa undergo the acrosome reaction. To induce the acrosome reaction, 3 jelly components act in concert on the spermatozoa: a sulphated glycoprotein named acrosome reaction-inducing substance (ARIS), a group of steroidal saponins named Co-ARIS, and an oligopeptide presumably having an ability to increase the intracellular pH of the spermatozoon. All three are required to mimic the full ability of jelly coat to induce the acrosome reaction instantaneously. A combination of ARIS and Co-ARIS is enough for induction in normal sea water, although its action is almost 2 min slower than the jelly. ARIS can induce the acrosome reaction by itself in high Ca2+ or high pH sea water. When spermatozoa meet the jelly coat, the acrosome reaction is eventually induced because ARIS and Co-ARIS co-operatively increase the intracellular Ca2+ by stimulating verapamil- and maitotoxin-sensitive Ca2+ channels and the oligopeptide increases the intracellular pH by stimulating Na+/H+ exchange systems.

Acrosome↗
PubMed1990

[Changes in Po2, Pco2, pH, and HCO3 concentration and flow rates in human parotid saliva by tongue sour stimulation at various intervals].

The PO2, PCO2, pH, and HCO3- concentration and flow rates of parotid saliva were observed by tongue stimulation with 3% tartaric acid at various intervals in a human subject after about a one hour rest. The PO2, PCO2, pH, and HCO3- concentrations in parotid saliva were measured with a Blood Gas Analyzer System. The results are summarized as follows: 1) The mean PO2 and PCO2 of parotid saliva immediately before tongue stimulation were about 40 mmHg (range 33-44 mmHg) and 45 mmHg (41-48). There values were similar to those of venous blood. 2) PO2 increased to about 50 mmHg (46-54) 5 to 10 sec. after stimulation, and then 3 to 8 min. later, it decreased to a minimum value of about 28 mmHg (26-29) before returning to the resting level 15 min. after stimulation, when the intervals between stimulations were longer than 2 min., similar changes in PO2 were observed, whereas stimulations every 30 sec. or 1 min. had no effect on PO2. 3) PCO2 increased to about 98 mmHg (85-120) from the resting level of 45 mmHg (41-48) 5 to 10 sec. after stimulation, and returned to the resting level 1 min. after stimulation. When the intervals between stimulations were shorter than 20 min., the peak value of PCO2 by the first stimulation was higher than those induced by the following stimulations. When the interval was 30 sec. or 1 min., only the peak after the first stimulation was observed. 4) The pH of parotid saliva was about 7.4 (7.35-7.5) 30 to 50 sec. after stimulation, and it decreased below 6.5 about 12 min. after stimulation. When the interval between stimulations was 5 min., the pH of the parotid saliva after stimulation was always above 6.5. When the interval between stimulations was 1 min. or 30 sec., it remained at about 7.5. 5) The HCO3- concentration in parotid saliva depends almost exclusively on the pH when Pco2 remained unchanged. When Pco2 was high, however, the HCO3- concentration was affected by the change in Pco2. 6) There was no relationship between changes in the flow rate of parotid saliva and Po2, Pco2, pH, and the HCO3- concentration. Particularly, when the interval between stimulations was shorter than 5 min., the changes in flow rate had no effect on Po2, Pco2, pH, and the HCO3- concentration.

Blood Gas Analysis↗
PubMed1990

[Effect of bite force on parotid secretion in human].

To determine the physiological roles of periodontal mechanoreceptors in parotid salivary secretion, we studied the effects of strength and frequency of unilateral bites on the salivary secretion from both sides of human parotid glands. Parotid saliva was collected bilaterally via modified Lashley cups, and the flow rate of parotid saliva was measured with a device using a strain gauge. The bite force was monitored with a pressure transducer. In the first experiment, subjects were constantly occluded for one minute at 80 strokes per minute at strengths of 5, 10, and 20 kg. In the second experiment, subjects were occluded for one minute at a constant force of 10 kg at frequencies of 20, 40, 80, and 120 strokes per minute, or subjects were continuously clenching for one minute. The flow rate of parotid saliva gradually increased with increasing bite strength, while it gradually decreased with increasing bite frequency. In unilateral bites, the salivary flow rate of the ipsilateral parotid gland was greater than that of contralateral parotid gland, at any strength and frequency. These results suggest that periodontal mechanoreceptors are involved in parotid salivary reflexes initiated by bite force stimuli.

Bite Force↗
PubMed1990

[Dose intensity and clinical response in patients with advanced gastric carcinoma treated by induced hypertension chemotherapy].

Dose Intensity (DI) was analyzed among 52 eligible and complete patients with advanced gastric carcinoma receiving ADM, 5-FU & MMC (AFM) combination regimen under angiotensin II Induced Hypertension Chemotherapy (IHC). In the induction period DI of CR either in the initial response time or in the effective tumor reduction time was smaller than that of PR, although DI of total period of AFM administration was not different. Based on the evidences, heterogeneous distribution in tumor blood flow under normotension got improved under hypertension by angiotensin II, and chemotherapeutic effects were enhanced. A possibility of the reduction of doses of the drugs administered was suggested. In the maintenance, based on the clinical results, it is mentioned that DI is also useful for an indicator to decide the doses and continuation periods of drugs to be administered. Further investigation on DI will lead to obtain much better maneuver of chemotherapy.

Angiotensin II↗
PubMed1989

Characterization of a mitogen-activated, Ca2+-sensitive microtubule-associated protein-2 kinase.

We have previously found that treatment of quiescent mammalian fibroblast cells with several mitogenic factors activates in common a Ca2+-sensitive serine/threonine-specific protein kinase activity toward microtubule-associated protein 2 (MAP2) [Hoshi, M., Nishida, E. and Sakai, H. (1988) J. Biol. Chem. 263, 5396-5401]. Here, we characterized the mitogen-activated MAP2 kinase activity in rat 3Y1 cells. The activated kinase activity was detected in the cytosolic fraction but not in the membrane fraction. The inhibitory effect of Ca2+ on the kinase activity was reversible. Kinetic analyses revealed that the apparent Km values of the kinase activity for MAP2 and ATP were 1.6 microM and 30 microM, respectively. Free Ca2+ at 4 microM decreased apparent Vmax values for MAP2 and ATP without changing the apparent Km values. The MAP2 kinase had an apparent molecular mass of about 40 kDa as determined by gel filtration and by sucrose density gradient centrifugation. Myelin basic protein as well as MAP2 could serve as good substrates for this kinase, but 40S ribosomal protein S6, casein, histone, phosphorylase b, protamine, tubulin, actin and tau could not. These properties of the enzyme indicate that the Ca2+-sensitive MAP2 kinase may be a previously unidentified enzyme. Down-regulation of protein kinase C by prolonged phorbol ester treatment abolished the MAP2 kinase activation by phorbol ester, but did not prevent the MAP2 kinase activation by epidermal growth factor (EGF) or fresh serum. This suggests that the Ca2+-sensitive MAP2 kinase could be activated through protein-kinase-C-dependent and -independent pathways. Activation of the MAP2 kinase occurred shortly after the addition of EGF or phorbol ester even in the presence of protein synthesis inhibitors (cycloheximide, puromycin and emetin). Moreover, treatment of the EGF- or phorbol-ester-activated MAP2 kinase with acid phosphatase inactivated the kinase activity. Thus, the MAP2 kinase may be activated through phosphorylation.

Animals↗
PubMed1989

Selection of mouse preimplantation embryos carrying exogenous DNA by polymerase chain reaction.

A polymerase chain reaction (PCR) system to detect transgenes in mouse preimplantation embryos was employed so that transgenic embryos could be selected before they were transferred to recipient mice. The selection system involves bisection of morulae, selection of the half-morulae containing target sequences within 7 hr, and culture and transfer of the sister half-morulae. PCR analysis of morulae derived from transgenic mice confirmed that the PCR system was reliable. However, five of 41 implanted embryos derived from PCR-positive morulae did not contain the transgenes. Also, one of 28 implanted embryos from PCR-negative morulae were transgenic. The selection system was applied to fertilized mouse eggs into which pSV2-gpt-gE1A DNA was injected. The injected DNA was detected in 30 of 84 morulae derived from the microinjected eggs. All seven implanted embryos developed from PCR-negative morulae had no detectable amount of transgenes, and one of two successfully implanted embryos from PCR-positive morulae was transgenic.

Animals↗
PubMed1989

Pertussis toxin inhibits 1-methyladenine-induced maturation in starfish oocytes.

Starfish oocytes injected with pertussis toxin (3-6 micrograms/ml) or its catalytically active A-subunit (1 microgram/ml) did not undergo germinal vesicle breakdown in response to 1-methyladenine (1-10 microM). The pertussis block could be bypassed by transfer of cytoplasm that contained maturation-promoting factor (MPF). After insemination, pertussis-blocked, MPF-rescued oocytes underwent cortical vesicle exocytosis and cleavage. These results suggest the involvement of a pertussis sensitive G-protein in the pathway coupling 1-methyladenine action at the cell surface to the reinitiation of meiosis.

Adenine↗
PubMed1989

Inhibition of starfish oocyte maturation by leupeptin analogs, potent trypsin inhibitors.

Inhibition of subsite-substituted leupeptin analogs, potent trypsin inhibitors, on 1-methyladenine-induced germinal vesicle breakdown was investigated in a starfish, Asterina pectinifera. Of benzyloxycarbonyl(Z)-Leu-P2-argininals, the analog with Ser at P2 residue was the strongest inhibitor, and those with Pro, Leu greater than Thr greater than Gly were followed in this order. In Z-P3-Ser-argininals, ranking of the inhibitory ability was as follows: Phe greater than Leu much greater than Pro greater than Ala at P3 residue. Among 11 analogs synthesized, Z-Phe-Ser-argininal showed the strongest inhibition. The inhibitory potency of the analog was 100-fold stronger than that of leupeptin (acetyl-Leu-Leu-argininal). Thus, trypsin-like enzyme possessing a narrow subsite specificity participates in oocyte maturation in the starfish.

Adenine↗
PubMed1989

Dental radiography exposure of the Hiroshima and Nagasaki populations.

Dental radiography doses in Hiroshima and Nagasaki were estimated on the basis of survey data from dental hospitals and clinics in Hiroshima and Nagasaki, and doses were measured by thermoluminescent dosimeters and a phantom. Doses to organs, including the lens, pituitary fossa, thyroid gland, and skin were calculated from data obtained during a 2-week survey in both cities. The mean caput doses were calculated from the data indicating frequency per year and were tabulated by organs, age, teeth examined, type of examination, population, sex, and city. No significant difference was observed by age, population, sex, or city. Currently the doses incurred during dental radiography may not be sufficiently high to cause bias in the assessments for late radiation effects among atomic-bomb survivors. However, the mean caput thyroid doses of 62 mrad and 67 mrad in Hiroshima and Nagasaki, respectively, cannot be ignored from the standpoint of their potential in contributing to radiation-induced carcinogenesis.

Adolescent↗
PubMed1989

[Dosimetry of fast neutrons in 1W nuclear reactor with plastic nuclear-track detectors].

A nuclear reactor at Kinki University is operated at the maximum of 1W. It produces fission neutrons as much as gamma-rays. To facilitate its use for neutron radiobiology, fast neutrons inside the reactor were measured with nuclear-track detectors TS 16 N and a pair of ion chambers. The angular dependence of TS 16 N response, an anisotropy of fast neutron fluxes in the reactor and misuse of the kerma factor assumed for radiation protection business are the major causes of discrepancy is measured doses by the two methods. Correction factors for the three causes are proposed. After correction, neutron doses estimated with TS 16 N and chambers agree within 5%. The dose-rate at the reactor's center is about 20 tissue-cGy/h. This is the first in situ dosimetry of fast neutrons in a reactor with track detectors attached to biologic samples. Our routine usage has demonstrated that, if used with caution, TS 16 N elements are handy, reliable monitors for fast neutron dosimetry as they are insensitive to contaminated gamma-rays and small enough to be attached to biologic samples.

Fast Neutrons↗