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Biomedical subjects

E Suzuki

Publications and source records attributed to E Suzuki.

At least 343 records · Page 19Linked to original sources
PubMed1991

Immunoelectron microscopic study of the opsin distribution in the photoreceptor cells of Drosophila melanogaster.

Distribution of opsin in the compound eye of Drosophila melanogaster was examined by post-embedding immunoelectron microscopy using a monoclonal antibody against the Drosophila Rh1 opsin and gold-conjugated secondary antibody. Numerous gold particles were observed on the rhabdomeric microvilli of R1-R6 retinular cells. In the retinular cell body, gold particles were distributed in rough endoplasmic reticulum, subrhabdomeric cisternae (SRC), multivesicular bodies, and secondary lysosomes. In the rdgA mutant, whose SRC are absent, density of gold particles on the rhabdomeric microvilli was about 20% of normal. These results suggest the involvement of SRC in opsin transport.

Animals↗
PubMed1990

NMR characteristics of intracellular K in the rat salivary gland: a 39K NMR study using double-quantum filtering.

Intracellular K of the perfused rat mandibular salivary gland was measured by 39K NMR spectroscopy at 8.45 T. Multiple-quantum NMR arising from multiple-exponential decay was used to eliminate the resonance due to extracellular K in the perfused gland at 25 degrees C. The resonance due to intracellular K consisted of two Lorentzian signals stemming from the [spin 1/2 to -1/2] coherence (sharp resonance) and the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences (broad resonance). The transverse relaxation time (T2) corresponding to the [spin 1/2 to -1/2] coherence was ca. 2.5 ms, and that corresponding to the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences was ca. 0.4 ms. The relaxation time of the double-quantum coherence of rank 3 (originating from product operators like Ix2Iz) was determined to be ca. 0.2 ms. These results suggest the possibility of the presence of a single homogeneous population of intracellular K with a correlation time of ca. 2.5 x 10(-8) s and a quadrupolar coupling constant of ca. 1.4 MHz.

Animals↗
PubMed1990

The three-dimensional structure of the seed storage protein phaseolin at 3 A resolution.

The polypeptides of the trimeric seed storage protein phaseolin comprise two structurally similar units each made up of a beta-barrel and an alpha-helical domain. The beta-barrel has the 'jelly-roll' folding topology of the viral coat proteins and the alpha-helical domain shows structural similarity to the helix-turn-helix motif found in certain DNA-binding proteins.

Amino Acid Sequence↗
PubMed1990

Effect of dietary alpha-linolenate/linoleate balance on crescent type-anti-glomerular basement membrane nephritis in rats.

Rats were fed diets with three different ratios of alpha-linolenate (18:3 n-3) and linoleate (18:2 n-6), and then crescentic-type anti-glomerular basement membrane (GBM) nephritis was induced. The urinary protein levels and the plasma urea nitrogen levels were significantly higher, and histological abnormalities of glomeruli were seen more frequently in the high-alpha-linolenate group than in the high-linoleate group. The differences in dietary alpha-linolenate/linoleate balances were reflected in the proportions of arachidonate and eicosapentaenoate in glomerular phospholipids. Our results indicate that dietary enrichment with alpha-linolenate causes unfavorable effects in this anti-GBM nephritis model.

Animals↗
PubMed1990

Renal effects of atrial natriuretic peptide during dopamine infusion.

To study whether the renal effects of atrial natriuretic peptide (ANP) are different from those of dopamine, we compared the effects of dopamine and dopamine plus ANP on renal circulation. Dopamine was infused at 1 microgram/kg/min for 120 min into 7 patients with essential hypertension (EH) and 5 normotensive subjects (NT). After 40 min of dopamine infusion, ANP infusion at 25 ng/kg/min was added to dopamine for 40 min. Before, during and after the infusion, renal function and nephrogenous cGMP were determined. Dopamine did not influence blood pressure, but increased urinary Na excretion (UNaV) by 100% in EH and NT. Addition of ANP further increased UNaV by 90%, but increases in UNaV were greater in EH than in NT. Renal blood flow was increased only by dopamine, while glomerular filtration rate (GFR) was increased by both dopamine (+8%) and dopamine plus ANP (+7%) as a whole, resulting in a significant increase in filtration fraction by the addition of ANP. Plasma and urinary cGMP and nephrogenous cGMP were elevated only during ANP infusion. These results suggest that the effects of ANP and dopamine on both GFR and UNaV were additive. However, in contrast with dopamine, ANP increased efferent resistance and nephrogenous cGMP, suggesting that the renal effects of ANP are different from those of dopamine.

Adult↗
PubMed1990

Adenosine triphosphate compartmentation in the rat heart: a 31P spin-lattice relaxation study.

Longitudinal relaxation times (T1) of phosphorus compounds in the perfused rat heart and erythrocytes were measured using the 31P Driven-Equilibrium Single-Pulse Observation of T1 relaxation (DESPOT) method at 33 degrees C. Both creatine phosphate in the heart and the three phosphate groups of adenosine triphosphate (ATP) in erythrocytes showed single-exponential relaxation. The three phosphate groups of ATP in the heart, however, had two T1 components. The T1 values of the short and the long T1 components of the beta-phosphate of ATP were ca. 0.4 and 14 s, respectively. The fraction with the long T1 represented ca. 30% of the total ATP content. These results suggested that there were two major pools of intracellular ATP in the rat heart which could be determined by 31P NMR spectroscopy.

Adenosine Triphosphate↗
PubMed1990

Role of human herpesvirus 6 infection in infants with exanthema subitum.

Twenty-two infants with exanthema subitum and their mothers were studied for human herpesvirus 6 (HHV-6) infection. HHV-6 was isolated from 13 of the 22 infants, in 5 infants by cultivation of their peripheral blood mononuclear cells and in the other 8 infants by cocultivation of their mononuclear cells with those from newborn cord blood. Of the 22 infants 19 showed a 4-fold or greater rise in HHV-6 antibody titers between the acute and convalescent stages of the disease. These findings support the contention that HHV-6 causes exanthema subitum. Attempts at isolation of HHV-6 from the saliva and peripheral blood mononuclear cells of the mothers of 14 of the 22 infants were unsuccessful. Serum samples from 22 mothers were all reactive to HHV-6 antigens, as evidenced by immunofluorescence and radioimmunoprecipitation analyses.

Antibodies, Viral↗
PubMed1990

Different desensitization mechanisms of two alpha 1-adrenoceptor subtypes in the contraction of rabbit aorta.

Using alpha 1-adrenoceptor selective antagonists chlorethylclonidine (CEC) and WB4101, both functional and radioligand binding studies showed that rabbit aorta contains at least two pharmacologically distinct alpha 1-adrenoceptor subtypes of approximately 10% alpha 1a and 90% alpha 1b receptors, and that each receptor subtype has a distinct role in the alpha 1-adrenoceptor-mediated vasoconstrictive response through different biochemical mechanisms for increasing intracellular Ca2+; alpha 1a receptors cause tonic response predominantly dependent on the influx of extracellular Ca2+, while alpha 1b receptors stimulate phosphoinositides (PI) hydrolysis/intracellular Ca2+ mobilization and cause phasic response mainly independent of extracellular Ca2+. Incubation of rabbit aorta with 10 microM noradrenaline (NA) for 2 h resulted in a reduction in the phasic response and PI hydrolysis to NA with no change in the tonic response. Similar to the NA incubation, the protein kinase C stimulator PMA (1 microM) selectively attenuated alpha 1b-receptor mediated PI hydrolysis and phasic contraction but had little effect on alpha 1a-receptor-mediated tonic response. The protein kinase C inhibitor H-7 (10 microM) blocked these inhibitory effects of PMA. Treatment with H-7 (10 microM) prevented the NA-induced alpha 1b receptor desensitization in inositol monophosphate (IP) formation and phasic response. The results suggest that activation of C kinase may be involved in the development of selective desensitization of alpha 1b receptors by a short-time in vitro incubation of NA.

Adrenergic alpha-Antagonists↗
PubMed1990

Role of penicillinase plasmids in the stability of the mecA gene in methicillin-resistant Staphylococcus aureus.

The stability of methicillin resistance (Mcr) in three independent clinical isolates, MR108, MR6, and MR61, of methicillin-resistant Staphylococcus aureus (MRSA) was studied. The Mcr phenotype was stably maintained in the progeny of all three MRSA clones carrying penicillinase plasmids. However, when the clones were tested after elimination of the plasmids, methicillin-susceptible (Mcs) subclones appeared at various frequencies. Seven Mcs subclones were classified into two groups based on their stabilities. Five Mcs subclones, which were derived from homogeneous strains MR108 and MR61, were stably susceptible. They lost penicillin-binding protein 2' production, and moreover, the mecA gene was deleted in four of five subclones. Two subclones were derived from heterogeneous strain MR6. They were very unstable, and more than half of their progeny were Mcr revertants. However, the remainder were stably Mcs and had lost penicillin-binding protein 2' and the mecA gene. We propose that penicillinase plasmids, which are present in most MRSA strains, play an important role in the stability and phenotypic expression of the mecA gene.

Blotting, Southern↗
PubMed1990

Potassium-39 nuclear magnetic resonance observation of intracellular potassium without chemical shift reagents during metabolic inhibition in the isolated perfused rat heart.

The intracellular potassium content of perfused rat heart was measured by potassium-39 nuclear magnetic resonance (NMR) spectroscopy at 33 degrees C with an inversion recovery technique based on the fact that the spin-lattice relaxation time (T1) of the intracellular potassium (8.3 msec at 8.45 T) is much faster than that of the extracellular potassium (68 msec). Intracellular potassium decreased to 60.2 +/- 4.3% of the control level (mean +/- SEM, n = 6) at 40 minutes from the start of metabolic inhibition (2 mM cyanide, 0 mM glucose). Removal of cyanide restored intracellular potassium to 94.2 +/- 3.9% at 30 minutes from the restart of oxidative metabolism. The cumulative potassium loss was determined from the flow rate and potassium concentration of the coronary effluent, which reached 139 +/- 12 mumol/g dry wt during 40 minutes of metabolic inhibition. This value was calculated as 41.8% of intracellular potassium in the control heart and agreed with the decrement of intracellular potassium measured by NMR. During the metabolic inhibition and recovery period, a linear correlation was observed between the changes in 39K NMR-observed intracellular potassium and the cumulative potassium loss. The present results evaluate the inversion recovery technique as a method to successfully monitor the myocardial intracellular potassium.

Animals↗
PubMed1990

Stability and degradation pattern of cefpirome (HR 810) in aqueous solution.

The stability and degradation pathways of a new semi-synthetic cephalosporin, 1-[[(6R,7R)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-ox o-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5H-1- pyridinium hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) sulfate (cefpirome sulfate, HR 810), were studied. Cefpirome in various buffer solutions was allowed to stand at 40 degrees C and its degradation patterns were investigated by high performance liquid chromatography. Cefpirome was stable in the region of pH 4-7 and slightly unstable beyond this range. In aqueous solution from the neutral to alkaline regions, the produced degradation products were: 1- [[(6R,7S)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-oxo -5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5 H-1- pyridinium hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) (epi-cefpirome); 1-[[(6R,7R)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-ox o-5-thia-1-azabicyclo[4.2.0]oct-3-en-3-yl]methyl]-6,7-dihydro-5H-1- pyridinum hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) (delta 2-cefpirome); 2-[[(2-amino-4-thiazolyl)((Z)-methoxy-imino)acetyl]amino]acetaldehyde; and 6,7-dihydro-5H-1-pyrindine. On the other hand, 1-[[(6R,7R)-7-[2-(2- amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-oxo-5-thia-1- azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5H-1-pyridinium++ + hydroxide, inner salt, 7(2)-(E)-(O-methyloxime) (anti-cefpirome), 2-[[(2- amino-4-thiazolyl)-((Z)-methoxyimino)-acetyl]aminomethyl]-1,2,5,7- tetrahydro-7-oxo-4H-furo[3,4-D]-[1,3]thiazine, and 6,7-dihydro-5H-1- pyrindine were produced in strongly acidic solution or under irradiation by artificial sunlight.

Cephalosporins↗
PubMed1990

Net vitamin C activity of erythorbic acid in guinea pigs.

The enzyme activities, which are influenced by the vitamin C level in tissues, were measured to evaluate the vitamin C activity of erythorbic acid (ErA) in guinea pigs administered ErA. Guinea pigs were divided into two groups: animals in one group (control group) were administered 1, 5, and 100 mg/day ascorbic acid (AsA) and those in the other group (supplemented group) were administered 1, 5, 20, and 100 mg/day ErA for 16 days. At the end of the experimental period, they were sacrificed, blood was collected, and their livers were removed. The activities of liver aniline hydroxylase, of liver acid phosphatase, and of serum alkaline phosphatase, and the content of liver cytochrome P-450 were assayed. The activities of aniline hydroxylase and serum alkaline phosphatase and the content of liver cytochrome P-450 of the guinea pigs administered 1 mg ErA were lower than those of the guinea pigs administered 1 mg AsA. However, the enzyme activities and liver cytochrome P-450 content in the guinea pigs administered 5 mg or more of ErA were similar in level to those in the guinea pigs administered 5 mg AsA. These results suggested that administration of a considerably high amount of ErA to guinea pigs showed a similar vitamin C activity to that of AsA, which might suggest that vitamin C activity of ErA may be more than one-twentieth that of AsA, as has been generally believed.

Acid Phosphatase↗
PubMed1990

Effects of proxigermanium on interferon production and 2',5'-oligoadenylate synthetase activity in the lung of influenza virus-infected mice and in virus-infected human peripheral blood mononuclear cell cultures.

Proxigermanium (SK-818) is a synthesized organic germanium compound having various biological activities. The effects of proxigermanium on interferon (IFN) production in mice infected with influenza virus and virus-infected human peripheral blood mononuclear cells (hPBMC) were investigated. Proxigermanium alone did not induce IFN production in normal mice or in hPBMC without viral infection. On the other hand, proxigermanium enhanced alpha/beta IFN production in viral-infected mice and hPBMC. Since proxigermanium is known to have antiviral activity in vivo but not in vitro, it is likely that the IFN production augumenting activity of proxigermanium is involved in its antiviral activities.

2',5'-Oligoadenylate Synthetase↗