Biomedical subjects

N Morisaki

Publications and source records attributed to N Morisaki.

At least 91 records · Page 5Linked to original sources

PubMed1994

A naturally occurring mutation at the second base of codon asparagine 43 in the proposed N-linked glycosylation site of human lipoprotein lipase: in vivo evidence that asparagine 43 is essential for catalysis and secretion.

The patient was a 20-year-old male. His fasting plasma triglyceride and cholesterol levels were 1258 mg/dl and 138 mg/dl, respectively. The lipoprotein lipase (LPL) activity and mass from postheparin plasma of the patient were 0.00 mumol/ml/h (normal range: 5.51 +/- 1.12) and 23 ng/ml (normal range: 220 +/- 42), respectively. DNA sequence analysis of the LPL gene from the patient revealed a homozygous nucleotide change: a A-->G transition at nucleotide position 383, resulting in an amino acid substitution of Ser for Asn43, which is believed to be an N-linked glycosylation site of the LPL mature protein. Expression studies of this mutant LPL cDNA produced an inactive LPL protein which was not secreted into the media.

Adult↗

PubMed1994

Role of phospholipase A2 in expression of the scavenger pathway in cultured aortic smooth muscle cells stimulated with phorbol 12-myristate 13-acetate.

We have demonstrated that cultured intimal smooth muscle cells (SMC) from thickened intima can metabolize acetylated low-density lipoprotein (LDL) by a scavenger pathway, but medial SMC from normal arteries cannot. In this study we investigated the expression mechanism of the scavenger pathway in medial SMC using a phorbol ester. Medial SMC were incubated with 10(-10)-10(-7) M phorbol 12-myristate 13-acetate (PMA) for 1-24 h and then their degradation of 125I-labelled acetylated LDL was assayed. Unstimulated SMC degraded little acetylated LDL, but incubation for 24 h with PMA dose-dependently stimulated its degradation by SMC, the optimal PMA concentration being 1 x 10(-8) M. Induction of expression of the scavenger pathway required more than 4 h of incubation with PMA and was completely inhibited by cycloheximide. In addition expression of the scavenger pathway was not transient but stable. Induction of expression of the scavenger pathway by PMA was not inhibited by protein kinase C inhibitors, but was inhibited about 50% by phospholipase A2 inhibitors. The study, using various phorbol esters, indicated that induction of the scavenger pathway was well correlated with their ability to stimulate phospholipase A2 in medial SMC but not with their ability to activate protein kinase C. Moreover, incubation with exogenous phospholipase A2 (0.1-10 units/ml) or its product, lysophosphatidylcholine (0.01-100 micrograms/ml) dose-dependently increased degradation of 125I-labelled acetylated LDL in medial SMC. Lysophosphatidylcholine was most effective in various lysophospholipids. These results suggest that PMA induced the scavenger pathway in part by stimulating phospholipase A2 in medial SMC, and that a product, lysophosphatidylcholine, is a mediator of expression of the scavenger pathway.

Animals↗

PubMed1994

Platelet-derived growth factor is a potent stimulator of expression of intercellular adhesion molecule-1 in human arterial smooth muscle cells.

The effects of platelet-derived growth factor (PDGF) on the expression of intercellular adhesion molecule-1 (ICAM-1) as an indicator of cell activation were investigated in cultured human arterial smooth muscle cells (SMC). PDGF-BB and -AB but not -AA at 2-10 ng/ml stimulated ICAM-1 expression at a subconfluent but not a confluent state in a dose-dependent manner. ICAM-1 expression was induced at 2h, reached a plateau at 4h, and continued for at least 24h after stimulation with PDGF. The maximal stimulatory effect of PDGF-BB at 10 ng/ml was comparable to that by optimal concentrations of other cytokines and inflammatory agents. These data suggested that PDGF was a potent stimulator of ICAM-1.

Antigens, CD↗

PubMed1994

Migratory and proliferative effect of platelet-derived growth factor in rabbit retinal endothelial cells: evidence of an autocrine pathway of platelet-derived growth factor.

Angiogenesis is a crucial event in the progression of diabetic retinopathy. Migration and proliferation of endothelial cells (EC) are important steps in angiogenesis and are caused by angiogenic factors such as basic fibroblast growth factor (bFGF). In this work, capillary EC were isolated from rabbit retinal tissues and rabbit retinal EC (RREC) were found to secrete a migration factor for RREC in conditioned medium (CM). The activity was inhibited by an anti-platelet-derived growth factor (PDGF) antibody, but not by an anti-bFGF antibody. We also found that RREC showed a migratory response to PDGF. The response was induced by PDGF-BB and PDGF-AB dose dependently, but not by PDGF-AA, indicating that it was mediated by PDGF-beta receptor-dependent pathways, and that the PDGF-like factor was PDGF-BB or -AB. In addition, PDGF-BB induced the proliferation of RREC as well as bFGF. These data indicate that RREC have an autocrine pathway of PDGF by the secretion of and the response to PDGF. PDGF may play significant parts in angiogenesis in the progression of diabetic retinopathy.

Animals↗

PubMed1994

Phosphorylative inactivation of rifampicin by Nocardia otitidiscaviarum.

Rifampicin was inactivated by Nocardia otitidiscaviarum to yield two products designated RIP-3 and RIP-4. The full structures of RIP-3 and RIP-4 were determined to be 21-(O-phosphoryl) rifampicin and 3-formyl-21-(O-phosphoryl) rifamycin SV, respectively, but neither product had any antimicrobial activity.

Biotransformation↗

PubMed1994

Enhanced arterial intimal thickening after balloon catheter injury in diabetic animals accompanied by PDGF beta-receptor overexpression of aortic media.

Cultured aortic smooth muscle cells (SMC) of diabetic rats and rabbits, which overexpress platelet-derived growth factor (PDGF) beta-receptor compared with controls, have a unique phenotype. In this study we report on the PDGF beta-receptor overexpression in aortas of diabetic animals and the increased intimal thickening of carotid arteries in diabetic rabbits after balloon catheter injury compared with that in controls. In diabetic aortas with no treatments of balloon catheter injury, intimal thickening was not observed in spite of the overexpression of PDGF beta-receptor, indicating that the growth property of medial SMC in diabetic aortas was changed before the intimal thickening could take place. PDGF is known to be the main contributor to the intimal thickening induced by balloon catheter injury, which is one of several forms of arterial injuries. Intimal thickening after balloon catheter injury in diabetic rabbits increased compared with that in controls. These results imply that PDGF beta-receptor overexpression of SMC in medial layers plays an important role in intimal thickening in the formation of advanced diabetic macroangiopathy.

Animals↗

PubMed1994

Diabetic control and progression of retinopathy in elderly patients: five-year follow-up study.

OBJECTIVE: To assess whether control of diabetes mellitus is as important in the elderly as in young and middle-aged diabetic patients in terms of progression of retinopathy. DESIGN: A 5-year longitudinal cohort study. SETTING: Outpatient diabetic clinic. PATIENTS: One hundred fourteen non-insulin-dependent diabetic patients (30 males, 84 females) > or = 60 years of age. MEASUREMENTS: Retinopathy was checked at the beginning and end of the follow-up period. During the 5-year follow-up period, demographic variables, body mass index, HbA1c, blood pressure, and plasma lipids were monitored. Retinopathy was classified as follows: grade 0, no lesion; grade 1, non-proliferative retinopathy; grade 2, pre-proliferative retinopathy; grade 3, proliferative retinopathy. Progression of retinopathy during the 5-year follow-up was defined as an increase in its grade. RESULTS: At the start of the study, 13% of the patients already had retinopathy, all of grade 1. The 5-year follow-up study showed that progression of retinopathy was 23.6% in all cases, 22.2% in those with grade 0 initially, and 33.3% in those with grade 1 initially. The progression rates of retinopathy as a function of the mean HbA1c during the follow-up were as follows: lower than 7%, 2%; 7-8%, 20%; 8-9%, 40%; more than 9%, 61%. Multiple logistic regression analysis showed that, of the parameters examined, only HbA1c was a significant risk factor for progression of retinopathy. CONCLUSIONS: Control of diabetes mellitus is the most important factor associated with prevention of progression of retinopathy in elderly patients.

Aged↗

PubMed1994

Lipoprotein(a) is a risk factor for diabetic retinopathy in the elderly.

OBJECTIVE: To assess whether serum lipoprotein(a) is a risk factor for diabetic retinopathy in the elderly. DESIGN: A cross-sectional study. SETTING: Outpatient diabetic clinic. PATIENTS: One hundred four noninsulin-dependent diabetic patients (35 males, 69 females). Twenty-three were less than 60 years of age (middle-aged), and 81 were 60 years or older (elderly). MEASUREMENT: Levels of lipoprotein(a) (Lp(a)) and lipids were measured in fasting serum. HbA1c was also measured as an indicator of diabetic control. Other indicators possibly related to retinopathy were also checked. Retinopathy was estimated by photographs of fundi. RESULTS: Significantly higher indicators in the group with retinopathy than in the group without were: HbA1c, Lp(a), duration of diabetes, and systolic blood pressure (BP) in the total cases; HbA1c, duration of diabetes, and Lp(a) in the middle-aged; HbA1c, systolic BP, and Lp(a) in the elderly. Multiple logistic regression analysis showed that only HbA1c and Lp(a) were independent risk factors for retinopathy in all cases and in the elderly. The incidence of retinopathy was positively correlated to serum Lp(a) levels. CONCLUSION: Lp(a) is an independent risk factor for diabetic retinopathy.

Aged↗

PubMed1994

Inactivation of the macrolide antibiotics erythromycin, midecamycin, and rokitamycin by pathogenic Nocardia species.

A survey of five Nocardia spp. with respect to susceptibility towards three macrolides (erythromycin, rokitamycin, and midecamycin) showed that the Nocardia spp. have different susceptibility profiles. Most of the resistance was due to the inactivation of the macrolides by phosphorylation, glycosylation, reduction, deacylation, or a combination thereof.

Biotransformation↗

PubMed1993

The phospholipase-A2 reaction leads to increased monocyte adhesion of endothelial cells via the expression of adhesion molecules.

Mononuclear cell invasion into the vascular-vessel wall is a very important initial step in the development of atherosclerotic lesions. Hypercholesterolemia leads to a marked adhesion of circulating blood monocytes to arterial endothelial cells in vivo, and minimally oxidized low-density lipoprotein enhances monocyte adhesion to endothelial cells in vitro. The activation of phospholipase A2 (PLA2) is also important in the oxidation of low-density lipoprotein by endothelial cells. In this study, we investigated the role of PLA2 activation in the adhesion of a leukemic monocyte cell line (THP-1 cells) to endothelial cells in vitro using an adhesion assay and a cell-ELISA technique. The treatment of human umbilical-cord-vein endothelial cells with PLA2 stimulators such as interleukin-1 beta, tumor necrosis factor and lipopolysaccharide all increased the adhesion of THP-1 cells to endothelial cells. Exogenous PLA2 also increased the adhesion of these cell types. The increased adhesion induced by these PLA2 stimulators, as well as PLA2 itself, was reversed by various inhibitors of the PLA2 reaction. A product of the PLA2 reaction, lysophosphatidylcholine, also increased cell adhesion. A cell-ELISA technique showed the enhanced expression of vascular-cell-adhesion-molecule 1 and intercellular-adhesion-molecule 1 to endothelial cells after treatment with PLA2 stimulators, PLA2 or lysophosphatidylcholine. These results suggest that the PLA2 reaction enhances monocyte adhesion to endothelial cells through the expression of cellular adhesion molecules.

Cell Adhesion↗

PubMed1993

Purification and characterization of an autocrine migration factor for vascular smooth muscle cells (SMC), SMC-derived migration factor.

Migration of medial smooth muscle cells (SMC) into the intima is a key step in intimal thickening of atherosclerotic tissues. We previously reported that cultured SMC secrete a potent migration factor for SMC, named SMC-derived migration factor (SDMF). We purified this factor to homogeneity from 20 liters of serum-free conditioned medium of cultured rat aortic SMC by sequential heparin-Sepharose column, red-Sepharose column, TSK-heparin high performance liquid chromatography (HPLC) column, and Superose 6 HPLC column chromatographies. SDMF was found to be a 58-kDa polypeptide by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Reduction by mercaptoethanol caused only a slight decrease in its molecular mass to 53 kDa. Preparative isoelectric focusing revealed that SDMF is a basic protein with a pI of approximately 10. Purified SDMF enhanced the migration of rat SMC dose dependently, its maximal activity being 4 times that of platelet-derived growth factor-BB. In contrast, SDMF did not enhance the migration of endothelial cells from either human umbilical cord vein or rabbit retinal tissue. SDMF had no effect on the proliferation of SMC. These findings suggest that SDMF enhances SMC migration in vascular walls and that the autocrine system of SMC migration contributes to the formation of intimal thickening in atheroma formation.

Animals↗

PubMed1993

Angiogenic effects of advanced glycation end products of the Maillard reaction on cultured human umbilical cord vein endothelial cells.

The effects of advanced glycation end products (AGE) of the Maillard reaction on proliferation, migration and angiogenesis of cultured human umbilical vein endothelial cells (HUVEC) were studied. In an in vitro angiogenesis system, tube formation of HUVEC was dose-dependently stimulated by AGE at 0.5-50 micrograms/ml. Migration of HUVEC was also stimulated by AGE in a similar concentration range, and checkerboard analysis revealed that AGE were chemotactic but not chemokinetic. Proliferation of HUVEC was not affected by AGE. These data provide evidence that AGE are angiogenic.

Cell Movement↗

PubMed1993

Effect of side-chain structure on inhibition of yeast fatty-acid synthase by cerulenin analogues.

Yeast fatty-acid synthase (FAS) inhibition by cerulenin analogs with varying side-chain lengths was compared with that of cerulenin, tetrahydrocerulenin and iodoacetamide. Although inhibition by cerulenin was the highest, the analogs having (E,E)-delta 7,10 double bonds showed high inhibition. This strongly suggests that the (E,E)-delta 7,10 double bonds play an important role in the interaction of the inhibitors with the enzyme. It was suggested that the size of the hydrophobic cavity in the condensing enzyme terminates fatty-acid chain elongation by decreasing inhibition by the C18 analog. Like cerulenin itself, the shortest analog (C6) did not induce malonyl-CoA decarboxylase activity.

Acetyl Coenzyme A↗

PubMed1993

Diabetes mellitus induces accelerated growth of aortic smooth muscle cells: association with overexpression of PDGF beta-receptors.

The mechanism of diabetic macroangiopathy was studied from the view point of phenotypic change of aortic smooth muscle cells (SMC). The growth rates of cultured SMC of diabetic rats or rabbits were higher than those of non-diabetic animals (controls). This difference of the growth responses was observed specifically with platelet-derived growth factor (PDGF). Of the three PDGF dimers, PDGF-AB heterodimer (PDGF-AB) and PDGF-BB homodimer (PDGF-BB) stimulated growth of diabetic SMC more than that of control SMC but PDGF-AA homodimer (PDGF-AA) did not. The binding of 125I-PDGF to the diabetic SMC was greater than that to control SMC. This was due to increase in the number of cell surface receptors for PDGF. On in vitro culture, SMC from diabetic rats expressed more PDGF beta-receptor mRNA than SMC from non-diabetic rats. Moreover, in vivo, the aortic media of diabetic rabbits expressed PDGF beta-receptor mRNA, but that from non-diabetic rabbits did not. Thus diabetic SMC over-react on PDGF stimulation through over-expression of the PDGF beta-receptor gene. The significance of this fact in development of diabetic macroangiopathy is discussed.

Animals↗

PubMed1993

Decreased expression of the platelet-derived growth factor beta-receptor in fibroblasts from a patient with Werner's syndrome.

The study of Werner's syndrome, a premature ageing syndrome, may provide insight into the processes of natural ageing. We investigated the reason for the reduced growth potential of fibroblasts in Werner's syndrome which is considered to be similar to that of fibroblasts in normal senescence. The responses to different isoforms of platelet-derived growth factor (PDGF) of fibroblasts from a patient with Werner's syndrome (W-cells) and from a normal subject (control cells) were assessed by [3H]thymidine incorporation assay, a 125I-PDGF-AB binding experiment, and Northern blot analysis with a PDGF beta-receptor specific cDNA probe. PDGF-stimulated increase in [3H]thymidine incorporation in W-cells was much lower than that in control cells, especially with PDGF-AB and -BB as mitogens. The specific binding of 125I-PDGF-AB to W-cells was correspondingly lower than that to control cells. Furthermore, Northern blot analysis demonstrated a decreased basal level, and lack of PDGF-AB-induced up-regulation of the PDGF beta-receptor transcript in W-cells. Decreased expression of the PDGF beta-receptor due to decrease in its synthesis may be a causative factor of the decreased mitogenic response of W-cells to PDGF.

Cell Division↗

PubMed1993

Inactivation of rifampin by Nocardia brasiliensis.

Rifampin was glycosylated by a pathogenic species of Nocardia, i.e., Nocardia brasiliensis. The structures of two glycosylated compounds (RIP-1 and RIP-2) isolated from the culture broth of the bacterium were determined to be 3-formyl-23-(O-[beta-D-glucopyranosyl])rifamycin SV and 23-(O-[beta-D-glucopyranosyl])rifampin, respectively. Both compounds lacked antimicrobial activity against other gram-positive bacteria as well as the Nocardia species.

Glycosylation↗

PubMed1993

Tumour necrosis factor-alpha can modulate the phenotype of aortic smooth muscle cells.

In culture, rabbit aortic smooth muscle cells (SMC) from an atheroma differed phenotypically from SMC from normal media (M-SMC) in their growth rate, secretion of SMC-derived growth factor (SDGF), and metabolism of acetylated low density lipoproteins (a-LDL). The factor responsible for this in vivo phenotypic change of SMC was investigated in vitro. After preincubation of M-SMC with 0.1-10 U ml-1 of tumour necrosis factor-alpha (TNF) for 1-3 days, the cells grew faster than control cells and secreted a substantial amount of SDGF. The population doubling time and secretion of SDGF were inversely correlated. Moreover, after preincubation with TNF, the SMC metabolized [125I]a-LDL, unlike control M-SMC. These findings show that TNF can modulate the phenotype of SMC and suggest that it is important in the pathogenesis of atherosclerosis.

Animals↗

PubMed1993

Inactivated products of rifampicin by pathogenic Nocardia spp.: structures of glycosylated and phosphorylated metabolites of rifampicin and 3-formylrifamycin SV.

Rifampicin (1) was converted into four inactivated products by pathogenic Nocardia, RIP-1 and RIP-2 by N. brasiliensis and RIP-3 and RIP-4 by N. otitidiscaviarum. MS and NMR analysis showed the compounds to be 3-formyl-23-[O-(beta-D-glucopyranosyl)]rifamycin SV (2), 23-[O-(beta-D-glucopyranosyl)]rifampicin (3), 21-(O-phosphoryl)rifampicin (4) and 3-formyl-21-(O-phosphoryl)-rifamycin SV (5), respectively.

Drug Resistance↗