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Biomedical subjects

Y Matsuda

Publications and source records attributed to Y Matsuda.

At least 667 records · Page 37Linked to original sources
PubMed1993

[Molecular biology of hepatocyte growth factor (HGF)].

Hepatocyte growth factor (HGF) is the most potent mitogen of mature hepatocytes in primary culture, and is a molecule composed of 69 kD alpha-chain and 34 kD beta-chain. HGF predominantly acts on various epithelial cells as a mitogen, motogen and a morphogen. HGF mRNA and HGF protein increases rapidly in the liver and plasma of rats with liver injury such as hepatitis, ischemia, physical crush and partial hepatectomy. Production of HGF in the liver occurs in Kupffer cells, sinusoidal endothelial cells, and Ito cells, but not in hepatocytes. HGF mRNA is also rapidly increased in the intact organs such as lung, kidney and spleen. Thus, HGF may act as a hepatotrophic factor for liver regeneration through two mechanisms: a paracrine mechanism and an endocrine mechanism. Moreover, intravenously injected HGF enhances liver regeneration and protects hepatitis in vivo. Consequently, HGF may prove to be useful for the clinical treatment of patients with liver disease. Recently, we found a factor which specially appears in the blood of rats with organ injury and increases the synthesis of HGF, and it was named "injurin". IL-1 alpha and IL-1 beta are also positive regulators for the expression of the HGF gene, while TGF-beta and Dexamethazone down-regulate HGF expression.

Animals↗
PubMed1993

Long-term survival of a patient with bile duct carcinoma by endoscopic biliary drainage.

An 80-yr-old female presented with obstructive jaundice. Endoscopic retrograde cholangiopancreatography showed a carcinoma in the middle extrahepatic bile duct, and a biliary endoprosthesis was inserted. Exfoliative cytology of the bile and forceps biopsy of the tumor revealed a papillary adenocarcinoma. Surgical resection could not be done because of her cardiovascular complications, and neither chemotherapy nor radiotherapy was administered. Stents were exchanged and cleaned 21 times because of occlusion and cholangitis. Subsequent serial cholangiogram showed a slow growth of the papillary tumor, but local invasion to the adjacent organs or distant metastasis was not observed. The patient survived for 7 yr and 6 months after insertion of the biliary endoprosthesis.

Adenocarcinoma, Papillary↗
PubMed1993

Role of sympathetic nervous system in hypotension induced by platelet-activating factor in anesthetized dogs.

This experiment was designed to investigate whether platelet-activating factor (PAF)-induced hypotension in anesthetized dogs produces changes in sympathetic activity in the heart, kidney, liver, and adrenal gland in intact animals (n = 5) and in animals with complete systemic baroreceptor denervation (n = 5). Following intravenous injection of PAF (10 micrograms/kg) in animals with intact baroreceptors, systemic blood pressure fell significantly. However, sympathetic nerve activity in the kidney, liver, and adrenal gland revealed a biphasic pattern: an initial increase (within 30 sec) followed by a progressive reduction below the preinjection level. In contrast to these nerve responses to PAF, only cardiac nerve activity showed an initial and significant increase, and it remained elevated above the preinjection level until the end of the experiment (10 min). In animals with complete systemic baroreceptor denervation, these sympathetic responses to PAF did not differ significantly from the responses in the intact animals. These results indicate that intravenous injection of PAF produces differential control of sympathetic nerve activity in different organs. The contribution of systemic baroreceptors to reflex compensations is minor in PAF-induced hypotension.

Adrenal Glands↗
PubMed1993

Relative contribution of renal nerve and adrenal gland to renal vascular tone during prolonged canine hemorrhagic hypotension.

This study was designed to determine roles of renal sympathetic nerve activity (RNA) and adrenal catecholamines in the changes of renal vascular resistance during prolonged hemorrhagic shock in anesthetized dogs. In animals with intact baroreceptors, hemorrhagic hypotension (40 mm Hg) caused RNA to increase significantly within 1 min after bleeding, followed by a return to baseline within 10 min. Thereafter, a secondary increase in RNA occurred that was followed by a gradual decline towards the baseline level. The renal perfusion pressure (RPP) showed a progressive and significant increase until the end of the experiment. The initial increase in RNA was abolished by complete denervation of the systemic baroreceptors. The initial increase in RPP, which was observed within 10 min after bleeding in animals with intact baroreceptors, was attenuated by the denervation. In animals with bilateral adrenalectomy, RPP still showed an initial increase, but the progressive increase throughout the entire experimental period did not occur. In animals with baroreceptor denervation and bilateral adrenalectomy, RPP did not show any significant changes during the experiment. These results indicate that the initial renal vasoconstrictive response to hemorrhage is regulated by a reflex sympathetic mechanism. In contrast, a late renal vasoconstriction during hemorrhagic hypotension is predominantly evoked by humoral substances such as adrenal catecholamines.

Adrenal Glands↗
PubMed1993

Differential control of sympathetic outflow to kidney, heart, adrenal gland, and liver during systemic hypotension induced by cardiac tamponade in anesthetized dogs.

This study was designed to determine if cardiac tamponade-induced hypotension produces differential control in efferent sympathetic nerve activity to the kidney (RNA), heart (CNA), adrenal gland (AdNA), and liver (HNA) in pentobarbital-anesthetized dogs and to define whether systemic baroreceptors modify this response. We recorded RNA, CNA, AdNA, and HNA simultaneously during a 10 min period of sustained hypotension of 50 mm Hg, which was produced by intrapericardial saline infusion at 20 ml/min. When blood pressure reached 50 mm Hg, sympathetic nerve activity to all four organs increased significantly. Following this, RNA decreased significantly below the control (72 +/- 12%) at the end of experiment, while CNA, AdNA, and HNA remained elevated above control values throughout the experiment. Renal sympathoinhibition was reversed by cervical vagotomy, whereas this had no effect on CNA, AdNA, and HNA responses to hypotension. Additionally, the combined denervation of vagal, carotid sinus, and aortic nerves did not show any significant change in any variables. Thus these results indicate that hypotension due to cardiac tamponade in dogs produces an initial equivocal sympathoexcitation to the kidney, heart, adrenal gland, and liver followed by vagal afferent-mediated sympathoinhibition to the kidney but sustained excitation to the other three organs.

Adrenal Glands↗
PubMed1993

Changes in type IV collagen content in livers of patients with alcoholic liver disease.

An increase of serum type IV collagen levels in patients with liver disease has been reported; however, the mechanisms of this increase are not yet well known. We recently developed an assay system for type IV collagen content in liver biopsy specimens. In this study, type IV collagen content in the livers and sera of patients with alcoholic liver disease and nonalcoholic liver disease was determined. Serum and hepatic type IV collagen contents were measured with a one-step sandwich enzyme immunoassay system using monoclonal antibodies for human type IV collagen. Hepatic type IV collagen content increased significantly in liver disease. In alcoholic liver disease, type IV collagen content in patients with mild fibrosis was lower than that in advanced types of alcoholic liver disease. In nonalcoholic liver disease, hepatic type IV collagen content tended to increase with the progression of fibrosis. Type IV collagen content in alcoholic liver disease was significantly higher than that in the corresponding type of nonalcoholic liver disease. Hepatic total collagen content increased significantly in parallel with the progression of fibrosis in both alcoholic liver disease and nonalcoholic liver disease. The total collagen content in each type of alcoholic liver disease was significantly lower than that in the corresponding type of nonalcoholic liver disease. The ratio of type IV collagen to total collagen content was the highest in livers showing mild fibrosis, both in alcoholic liver disease and nonalcoholic liver disease, and decreased in parallel with the progression of fibrosis. The ratio in patients with alcoholic liver disease was significantly higher than that in those with the corresponding nonalcoholic liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen↗
PubMed1993

[Study on three patients with malignant glioma showing tumor reduction during maintenance therapy with MCNU].

Tumor regression occurred in three of 19 patients (15.8%) with malignant glioma during maintenance therapy using MCNU. In two patients, the tumor reduced 5 and 8 months after the initial treatment, respectively. In the remaining patient, though the maintenance therapy was interrupted for a while and consequently the tumor size increased, readministration of MCNU reduced the tumor size two months later. Therefore, since the antitumor activity of MCNU against malignant glioma seems to require a certain time depending on the case, it is recommended that MCNU be given as maintenance therapy for at least half a year.

Adult↗
PubMed1992

Stable expression of natriuretic peptide receptors: effects of HS-142-1, a non-peptide ANP antagonist.

We established clonal cell lines stably expressing each of two subtypes of membrane bound guanylate cyclases (GC-A and GC-B), which are known as natriuretic peptide receptors. Using these cell lines, we showed that GC-A is an ANP/BNP receptor, whereas GC-B is a specific receptor for CNP. Effects of HS-142-1, a novel non-peptide ANP antagonist, on GC-A and GC-B were examined by using these cells. In cells expressing either GC-A or GC-B, HS-142-1 inhibited cGMP production elicited by ANP or CNP with IC50 values of 1.8 micrograms/ml and 1.5 micrograms/ml, respectively, and also competitively blocked specific binding of the natriuretic peptides with IC50 values of 2.2 micrograms/ml and 3.3 micrograms/ml, respectively. These results indicate that HS-142-1 is a potent antagonist of CNP as well as ANP. We also showed that CNP suppressed the growth of cells expressing GC-B by 22% and that HS-142-1 blocked the antiproliferative action of CNP.

Animals↗
PubMed1992

Enhancing effect of wortmannin on muscarinic stimulation of phospholipase D in rat pheochromocytoma PC12 cells.

Wortmannin, a specific inhibitor of myosin light chain kinase (MLCK), enhanced carbachol-induced formation of [3H]phosphatidylethanol ([3H]PEt), a marker of phospholipase D (PLD) activity, in [3H]palmitic acid-labeled PC12 cells. The apparent EC50 value was 1.5 microM, and the effect was maximal at 3 microM and slightly attenuated at higher concentration. Wortmannin alone had no significant effect on [3H]PEt formation. The enhancing effect of wortmannin was observed at the initial increasing phase of [3H]PEt formation but not at the subsequent plateau phase. Wortmannin enhanced also phorbol ester-induced PLD activation. Although the precise mechanism remains to be clarified, these results suggest that MLCK may be involved in PLD regulation in PC12 cells.

Androstadienes↗
PubMed1992

Prevention of autoimmune insulitis in nonobese diabetic mice by expression of major histocompatibility complex class I Ld molecules.

Nonobese diabetic (NOD) mice spontaneously develop a T-cell-mediated autoimmune disease that is similar in many respects to insulin-dependent diabetes mellitus in humans. NOD mice were shown to express major histocompatibility complex class I Kd and Db antigens. To examine the possible involvement of major histocompatibility complex class I molecules in the development of autoimmune insulitis, we attempted to express a different type of class I molecule in NOD mice by crossing C57BL/6 mice transgenic for the class I Ld gene with NOD mice. The backcross progeny expressed the Ld antigen on the peripheral blood lymphocytes at a level comparable with that of the BALB/c mice. The cell surface expression of endogenous class I and class II antigens on the peripheral blood lymphocytes was not affected. Analysis of these mice revealed that the expression of the class I Ld antigen significantly reduced the incidence of insulitis at 20 weeks of age. In situ hybridization of a biotinylated probe on mouse chromosomes showed that the Ld transgene was located in the E area of chromosome 6 with which no genetic linkage to insulin-dependent diabetes mellitus was demonstrated. These results suggest that the NOD-type class I molecules are involved in the development of insulitis in NOD mice.

Animals↗
PubMed1992

Two thrombin-activated Ca2+ channels in human platelets.

The regulation of extracellular Ca2+ entry into fura-2-loaded human platelets was examined following stimulation with thrombin. In the presence of external Ca2+, stimulation of platelets with thrombin resulted in a rapid increase, followed by a plateau, in intracellular Ca2+ concentration ([Ca2+]i). Pretreatment with wortmannin, a specific inhibitor of myosin light chain kinase, suppressed only the plateau phase and had no effect on the initial rapid increase in [Ca2+]i. In Ca(2+)-free EGTA buffer, thrombin induced a transient and relatively small increase in [Ca2+]i caused by Ca2+ release from internal stores. When Ca2+ was added subsequently to the Ca(2+)-free medium within 10 min after thrombin activation, a marked increase in [Ca2+]i was seen, reflecting thrombin-stimulated external Ca2+ entry. With the Ca(2+)-free medium, wortmannin did not affect either the Ca2+ mobilization from the internal stores or the rapid external Ca2+ entry at early time points (within 5 s) after thrombin stimulation, whereas it significantly inhibited Ca2+ entry when Ca2+ was added later (at 3 min). Wortmannin inhibition of this late Ca2+ entry and that of 20-kDa myosin light chain phosphorylation after thrombin stimulation were dose- and preincubation time-dependent and correlated well with each other. These results suggest that two different channels are responsible for Ca2+ entry in human platelets at the early and late phases of thrombin stimulation and that the channel responsible for the late phase of Ca2+ entry may be activated by a mechanism involving myosin light chain kinase.

Androstadienes↗
PubMed1992

The ES-242s, novel N-methyl-D-aspartate antagonists of microbial origin, interact with both the neurotransmitter recognition site and the ion channel domain.

ES-242-1 approximately 5 are novel microbial bioxanthracenes which do not contain nitrogen. The ES-242s inhibited the binding of [3H]TCP and [3H]CGS19755 to the N-methyl-D-aspartate (NMDA) receptor complex. They had no effect on the binding of the specific ligands for the non-NMDA receptor. The biochemical and pharmacological properties of ES-242-1 were fully examined since it is the most potent of the five compounds. ES-242-1 is highly specific for the NMDA receptor; it has no effect on other receptors. Kinetic analyses indicated that ES-242-1 inhibited the binding of [3H]TCP and [3H]CGS19755 in a competitive manner, respectively, suggesting that ES-242-1 interacts with both the transmitter recognition site and the channel domain. ES-242-1 selectively inhibited NMDA-induced Ca2+ influx in primary cultures of mouse hippocampal neurons. ES-242-1 also specifically blocked the increase in cyclic GMP accumulation induced by NMDA or L-glutamate in rat cerebellar slices. In a concentration range of 0.1-1.0 microM, ES-242-1 was as potent as MK-801 in preventing glutamate-induced neurotoxicity in primary cultures of mouse hippocampal neurons. These results show that ES-242-1 is a potent and specific antagonist for the NMDA receptor. The antagonistic properties of the ES-242s appear to be due to a novel mechanism of action at the NMDA receptor.

Animals↗
PubMed1992

Inhibition of Ca(2+)-dependent catecholamine release by myosin light chain kinase inhibitor, wortmannin, in adrenal chromaffin cells.

To elucidate the possible involvement of myosin light chain kinase (MLCK) in the mechanism of exocytosis, we studied effects of MLCK inhibitor, wortmannin, on the secretory function of bovine adrenal chromaffin cells. Preincubation of chromaffin cells with wortmannin inhibited both acetylcholine- and high K(+)-evoked catecholamine (CA) release. The IC50 for high K(+)-evoked CA release was 1 microM. When the cells were permeabilized with digitonin after wortmannin preincubation, Ca(2+)-dependent exocytosis was inhibited in a dose-dependent manner (IC50, 1 microM). These findings suggest the implication of MLCK in the Ca(2+)-triggered process in the machinery of exocytosis.

Acetylcholine↗
PubMed1992

Primary structure and expression of a gamete lytic enzyme in Chlamydomonas reinhardtii: similarity of functional domains to matrix metalloproteases.

A gamete lytic enzyme (GLE) of Chlamydomonas reinhardtii is a zinc metalloprotease and mediates digestion of the cell walls of the two mating-type gametes during mating as a necessary prelude to cell fusion. The nucleotide sequence analysis of a cDNA revealed that GLE is synthesized in a preproenzyme form, a 638-amino acid polypeptide (Mr, 69,824) with a 28-amino acid signal peptide, a 155-amino acid propolypeptide, and a 455-amino acid mature polypeptide (Mr, 49,633). A potential site for autocatalytic activation was contained within the propolypeptide and a zinc binding site found within the mature polypeptide; both sites were highly homologous to those in mammalian collagenase. A putative calcium binding site was present in the near C-terminal region of the mature GLE. Both propolypeptide and mature polypeptide had potential sites for asparagine-linked glycosylation, and the Arg-(Pro)3 and Arg-(Pro)2 motifs, which are known to exist in hydroxyproline-rich glycoproteins of the Chlamydomonas cell wall. Northern blot analysis revealed that steady-state levels of the 2.4-kilobase GLE mRNA increased during growth and mitotic cell division in the vegetative cell cycle and also increased markedly during gametogenesis under nitrogen-starved conditions.

Amino Acid Sequence↗
PubMed1992

HS-142-1, a novel nonpeptide atrial natriuretic peptide (ANP) antagonist, blocks ANP-induced renal responses through a specific interaction with guanylyl cyclase-linked receptors.

HS-142-1, a novel microbial product, blocked 125I-labeled rat atrial natriuretic peptide (rANP) (= ANF(99-126)) binding to bovine adrenocortical membranes, where guanylyl cyclase-containing receptors are predominantly expressed. However, HS-142-1 only slightly inhibited [125I]rANP binding to bovine lung membranes where only a small portion of binding sites are coupled to guanylyl cyclase. Further, HS-142-1 only recognized the 135 kDa ANP receptor, which is considered to be the guanylyl cyclase-containing receptor based on the results obtained in affinity cross-linking studies with bovine adrenocortical and lung membranes. Under identical conditions, Atriopeptin I selectively recognized guanylyl cyclase-free receptors both in binding and affinity cross-linking experiments. When injected intravenously (1 mg/kg) to anesthetized rats, HS-142-1 abolished ANP-induced diuresis and natriuresis. These results suggest that HS-142-1 works in vivo through a specific interaction with the ANP functional receptor, and that HS-142-1 will be a powerful tool for understanding the physiological roles of ANP in distinction from its pharmacological effects.

Adrenal Glands↗