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Biomedical subjects

S Uchida

Publications and source records attributed to S Uchida.

At least 487 records · Page 27Linked to original sources
PubMed1986

[Pharmacokinetics of cefoperazone in end-stage renal failure patients on peritoneal dialysis].

Pharmacokinetics of cefoperazone (CPZ) was examined in 5 patients with end-stage renal failure on maintenance intermittent peritoneal dialysis. Blood levels of CPZ given as a 1 g intravenous bolus injection were not different whether a patient was on or off peritoneal dialysis. Peritoneal clearance of CPZ was 1.6-1.9 ml/min. Blood CPZ levels reached the therapeutic level within 30-120 minutes after an intraperitoneal administration of 1 g CPZ, and remained at the level at least for 3-5 hours. Side effects of CPZ were not observed in any patient. These data indicate that the peritoneal dialysis does not affect blood CPZ levels given intravenously and that effective blood levels of CPZ can be maintained for several hours after an intraperitoneal injection of the drug. Thus, CPZ is considered useful in renal failure patients on peritoneal dialysis.

Adult↗
PubMed1985

Multiple agonist binding sites of muscarinic acetylcholine receptors and their relation to the negative inotropic action of agonists in guinea-pig heart.

The Kd values of the multiple agonist binding sites in cardiac muscarinic receptors (mAChR) and pD2 values for negative inotropic actions were determined independently and their relation was examined. The guinea-pig cardiac mAChR is known to have three agonist binding sites (super-high (SH), high (H) and low (L) affinity agonist binding sites) for carbachol (CCh). Pilocarpine (Pilo) and oxotremorine (Oxo) distinguished two sites (higher (Ho/p) with pKd of 5.88 and 8.20, respectively, and lower (Lo/p) affinity agonist binding sites with pKd of 5.08 and 6.17, respectively). The effects of guanine nucleotide and sulfhydryl reagent indicated that the Ho/p site corresponded with the SH site for carbachol, and the Lo/p site with the H + L sites for carbachol. The pD2 values of CCh, Pilo and Oxo for negative inotropic actions on autocontraction of right atria were 5.38, 5.30 and 6.80, respectively. The pD2 values of CCh and Oxo on electrically stimulated contraction of left atria in the presence of isoproterenol were 5.80 and 6.46, respectively, thus being closely related to H or Lo/p agonist binding sites of mAChR.

Animals↗
PubMed1985

Structure-activity relations of conotoxins at the neuromuscular junction.

The anticholinergic actions of synthetic conotoxin GI analogues and their structure-activity relationships were studied. Conotoxins competitively blocked the nicotinic acetylcholine receptors in neuromuscular junctions of preparations of rat sciatic nerve, M. gastrocnemius and frog abdominal muscles. They did not have a ganglion-blocking action, at least in the parasympathetic ganglion, or an anti-muscarinic action. The pA2 values of the synthetic conotoxin analogues indicated that the major factors determining the activity of conotoxin are the structural conformation of the peptide defined by two disulfide bridges, and the presence of a proline residue and C-terminal amide.

Animals↗
PubMed1985

Effect of calcitonin gene-related peptide on contraction of striated muscle in the mouse.

We have found ultrastructurally calcitonin gene-related peptide-like immunoreactivity in the axon terminal within the synaptic trough of neuromuscular junction of the mouse. We determined, using pharmacological means, with a phrenic nerve-diaphragm preparation, that this peptide enhances muscle contraction during stimulation of the nerve fibers or direct stimulation of the muscle. This effect is probably brought about via the receptor for this peptide not the acetylcholine receptor.

Animals↗
PubMed1985

Discrepancy between alpha 1-adrenoceptor-mediated contraction and the occupation theory in rat vas deferens--possible existence of a 'silent' receptor.

The relation of the amount of alpha 1-adrenoceptors (alpha 1-R) with contraction to norepinephrine (NE) through alpha 1-R in rat vas deferens was examined by means of radiobinding assays. Treatment with dibenamine decreased the maximal contraction to NE with a decrease in the amount of alpha 1-R but the relation was not linear. The contractile response disappeared completely when 20% of the alpha 1-R still remained. Moreover, culture of dibenamine-pretreated muscle restored the contraction to NE without a significant increase in the amount of alpha 1-R in the muscle. These findings suggest that some alpha 1-R are 'silent' in the contraction of rat vas deferens in response to NE under physiological conditions.

Animals↗
PubMed1985

Recovery of the muscarinic cholinergic receptor from its down-regulation in cultured smooth muscle.

The recovery of the muscarinic cholinergic receptor (mAChR) from its down-regulation by long-term exposure to ACh was investigated. This was done to obtain information about regulation of the mAChR. Exposure of guinea-pig vas deferens to 30 microM ACh for 24 h decreased the amount of mAChR to 30% of the initial level, as measured with L-[3H]quinuclidinyl benzilate (QNB). The amount of mAChR was restored to 190% of its prewithdrawal level within 48 h of removal of ACh, without change in the KD value for L-[3H]QNB. This restoration was entirely dependent on protein synthesis. The half-life of the receptor was calculated to be 69 h. The recovery of mAChR was blocked by treatment with antimicrotubular agents, carboxylic ionophores, or 5 mM EGTA, which affect membrane protein synthesis. However, cytochalasin B and cyclic nucleotide derivatives had no effect. These data indicate that the recovery of mAChR was due to new synthesis of mAChR. The findings suggested that microtubules and the Golgi apparatus were involved in the biosynthesis of mAChR and that extracellular Ca2+ was necessary for the synthesis. Unlike the case with nicotinic AChR, the synthesis did not seem to be increased by cAMP or high extracellular Ca2+.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1985

Localization and properties of NAD+-dependent 15-hydroxyprostaglandin dehydrogenase activity in the rat kidney.

Localization of NAD+-dependent (type I) 15-hydroxyprostaglandin dehydrogenase (15PGDH) in the rat kidney was examined using an ultramicro assay of the enzyme activity based on the enzymatic cycling method. The enzyme activities during first 3 weeks of age were 30- to 40-fold higher than the adult and rapidly decreased by 4th week. 15PGDH activities measured with either PGE2 or PGF2 alpha as a substrate were five times higher in slices from midcortical or juxtamedullary layers than in slices from the superficial cortex of 3 week-old rat kidney. Little activity was found in inner medulla and papilla. When the enzyme activity was assayed using isolated nephron segments dissected from collagenase treated slices of 3 week-old rat kidneys, the activity was localized only in the proximal convoluted and straight tubules with either PGs (PGE2: 1.75 +/- 0.25 in PCT, 7.70 +/- 1.19 in PST, and PGF2 alpha: 1.63 +/- 0.39, 6.18 +/- 1.52 pmoles NADH/mm/40 min). The kinetic analysis for renal 15PGDH of 3 week-old rats revealed that Km for PGE2 (8.4 microM) was lower than that for PGF2 alpha (22.6 microM) with constant NAD+, while Vmax for both was similar. In contrast, both Km and Vmax for NAD+ were identical with either PGs. These data suggest that the rate-limiting factor of type I 15PGDH is the concentration of prostaglandins in the kidney rather than the concentration of NAD+.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1985

Effect of chronic metabolic acidosis on ammonia production from L-glutamine in microdissected rat nephron segments.

To evaluate the role of each nephron segment in renal ammoniagenesis, distribution of renal ammoniagenic activity along the nephron in control and acidotic rats was examined. We used our original aerobic incubation system and ammonia produced from glutamine in 7 defined segments of microdissected nephron was measured using the enzymatic cycling method. When ammonia production in the control was compared in each nephron segment, the highest specific activity of ammoniagenesis per mm tubular length and that per microgram protein were observed in the proximal straight tubule (PST) and the thick ascending limb of Henle's loop, respectively. Chronic metabolic acidosis increased ammonia production per mm tubular length markedly in the proximal convoluted tubule (PCT) (+171%), moderately in the medullary collecting tubule (+123%) and PST (+77%), and slightly in the distal convoluted tubule (+52%), revealing that the highest activity of ammoniagenesis was located in PCT and PST in acidosis. These data indicate that proximal tubules have major roles in renal ammoniagenesis both in the control and in acidosis. From the early observation of glutaminase I isoenzyme distribution along the nephron, our data suggest that not only phosphate-dependent glutaminase but also phosphate-independent glutaminase may have important roles in renal ammoniagenesis.

Acidosis↗
PubMed1985

Demonstration of T antigens on the surface of cells transformed with primate polyoma viruses.

Primate polyoma virus-transformed hamster, mouse, and rat cell lines were examined by indirect immunofluorescence staining for cell surface-associated T antigens, by using a rabbit antiserum prepared against sodium dodecyl sulfate-denatured large T antigen of simian virus 40 (anti-SV40-SDS-T serum). Positive surface staining was shown not only on SV40-transformed cells, but also on BK and JC virus-transformed cells. In contrast, normal cells and cells transformed with mouse polyoma-, human adeno-, and murine sarcoma viruses were negative. The data on SV40-transformed cells confirmed the reports of others demonstrating the cell surface location of SV40 large T antigen, and the data on BK and JC virus-transformed cells proved that these cells have cell-surface T antigens that cross-react with anti-SV40-SDS-T serum.

Animals↗
PubMed1985

Changes in density of muscarinic cholinergic receptor by adrenergic denervation with guanethidine.

The effects of chronic adrenergic denervation with guanethidine on muscarinic cholinergic receptors (mAChR) were investigated by binding of L-3H-quinuclidinyl benzilate (3H-QNB). Guanethidine treatment decreased the amount of mAChR from 102 to 87 fmoles/mg protein in the heart and from 444 to 388 fmoles/mg protein in the small intestine, but increased it from 223 to 282 fmoles/mg protein in the vas deferens, without changes in its characteristics. These findings suggested that adrenergic innervation has different influences on the mAChR population in different tissues.

Animals↗
PubMed1985

Participation of protein synthesis in development of supersensitivity in cultured rat vas deferens.

Organ culture of rat vas deferens produced supersensitivity to norepinephrine and acetylcholine in contractile response without change in alpha 1-adrenergic and muscarinic acetylcholine receptors. The development of supersensitivity was inhibited by low temperature and protein synthesis inhibitors. However, protein synthesis inhibitor had no significant effect on the receptors. These findings suggested that the supersensitivity may be induced by synthesis of protein(s) which have a stimulatory effect in a process(es) after activation of receptor to contraction.

Acetylcholine↗
PubMed1985

A histopathologic comparison of the tissue reaction to prosthetic materials in the knee joint of rats.

The five kinds of prosthetic materials: powders of cobalt alloy, stainless steel, alumina ceramic, HDP plastic and bone cement, were injected to the knee joints of 16 rats for each material. Two controls were used, one with saline solution and the other untreated. Some of the rats were sacrificed at one week, being left untreated. Some of the rats were sacrificed at one, four, 12 and 25 weeks after injection. The knee joints of these rats were taken out for a histopathologic study. The main changes were fibrosis and granulation due to foreign bodies, but no remarkable change in the degree of tissue reactions was observed within each material group, nor did the length of period have any effect thereon. Comparing the degree of the above changes caused by each material in the tissue, ceramic powder showed the most significant change, followed by bone cement, HDP, stainless steel and cobalt alloy powder, in that order. No tumorous condition was observed.

Animals↗