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Biomedical subjects

N Koga

Publications and source records attributed to N Koga.

At least 91 records · Page 5Linked to original sources

Pathological and angiographic regression of coronary atherosclerosis by LDL-apheresis in a patient with familial hypercholesterolemia.

We present the case of a 42-year-old male with familial hypercholesterolemia (FH) who had received long-term low-density lipoprotein (LDL)-apheresis before death occurred, presumably from an arrhythmia. He had been treated with double filtration plasmapheresis (DFPP) for 4 years and selective LDL adsorbent plasmapheresis (LAPP) for 2 years and 7 months. During the period of treatment (6 years and 7 months) he had received a total of 129 sessions of LDL-apheresis. Serum total cholesterol of the patient before the treatment was 638 mg/dl and during the treatment, the time-averaged values ranged from 336 mg/dl to 411 mg/dl for the first 4 years (with DFPP) and from 257 mg/dl to 364 mg/dl for the sequential 2 years and 7 months (with LAPP). Coronary angiograms were analysed for 13 segments of the coronary arteries using a digitized processing system. Analysis documented regression by identifying a reduction in percent stenosis from 34% to 20% in the proximal left circumflex artery (LCX), from 78% to 61% in the proximal right coronary artery (RCA), and from 92% to 72% in the middle RCA. In the other 10 segments analysed no significant regression and no progression were observed. The autopsy findings of the step-wise serial sections of the native coronary arteries did not record the formation of new and/or typical atheroma. In addition, a thickened intima, and an eccentric thickened wall lesion rich in collagen fiber were observed, although an accumulation of foam cells in the thickened wall lesions was found in some segments. This observation suggested scarring of the atheromatous plaque. We confirmed that LDL-apheresis performed over a period of 6 years and 7 months induced angiographic regression of coronary atherosclerosis in the patient with FH, and found that most of the atherosclerotic lesions were changed pathologically into sclerotic lesions rich in collagen fiber.

Adult↗

Metabolism in vitro of 3,4,3',4'- and 2,5,2',5'-tetrachlorobiphenyl by rat liver microsomes and highly purified cytochrome P-450.

Metabolism of two polychlorinated biphenyls, 3,4,3',4'- and 2,5,2',5'-tetrachlorobiphenyl (TCB), was studied using rat liver microsomes and the four forms of cytochrome P-450 (P-450), P-450b, P-450e, P-450c and P-450d. At first, effects of various inducers of P-450 such as phenobarbital (PB), 3-methylcholanthrene (MC), isosafrole (ISF) and pregnenolone 16 alpha-carbonitrile on the formation of metabolites of these TCBs by liver microsomes were compared. 3,4,3',4'-TCB was significantly metabolized by liver microsomes from MC-treated rats to form two previously reported metabolites, 4-hydroxy-3,5,3',4'-TCB and 5-hydroxy-3,4,3',4'-TCB with a relative ratio of 2.5:1. Incubation with microsomes from untreated or PB-treated rats produced none of the metabolites. On the other hand, 2,5,2',5'-TCB was metabolized to 3-hydroxy-2,5,2',5'-TCB most easily by liver microsomes from PB-treated rats and at a moderate rate by liver microsomes from ISF-treated rats. Activities of microsomes from untreated or MC-treated rats to hydroxylate 2,5,2',5'-TCB were low or undetectable. When these TCB hydroxylase activities were examined with a reconstituted system consisting of each P-450, reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase, dilauroylphosphatidylcholine and NADPH-generating system, only P-450c catalyzed both the 4- and 5-hydroxylations of 3,4,3',4'-TCB at a ratio of 2.2:1. On the contrary, the hydroxylation of 2,5,2',5'-TCB proceeded efficiently with P-450b and P-450e, being more efficient with the former. P-450d did not show any catalytic activity toward 3,4,3',4'-TCB and 2,5,2',5'-TCB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Cystic cavernous angioma--case report.

A rare case of a cystic cavernous angioma in a 20-year-old female was diagnosed preoperatively by magnetic resonance imaging and computed tomography. Total surgical removal resulted in a successful recovery. Cystic cavernous angioma is benign and can be completely-removed. The importance of magnetic resonance imaging in the differential diagnosis is emphasized.

Adult↗

Metabolism in vivo of the tropane alkaloid, scopolamine, in several mammalian species.

1. In vivo metabolism of scopolamine was studied in rats, mice, guinea pigs and rabbits. The structures of eight urinary metabolites including unchanged drug were elucidated by mass and nuclear magnetic resonance spectrometry. Determination of these metabolites was achieved by a g.l.c. method using a semi-capillary column. 2. The major metabolites in rats were the three phenolic metabolites, p-hydroxy-, m-hydroxy- and p-hydroxy-m-methoxy-scopolamine. 3. Significant intra-species difference of the metabolism was observed in rabbits. Tropic acid was the major metabolite in two rabbits out of three, while the other rabbit excreted mainly unchanged scopolamine, accompanied by five metabolites. Tropic acid was also the major metabolite in guinea pigs, but was of minor importance in mice. 4. The dehydrated metabolites, aposcopolamine and aponorscopolamine, were abundantly excreted in guinea pigs, moderately in mice, and least in rabbits and rats. 5. Excretion of glucuronide conjugates of scopolamine and norscopolamine were high in mice compared with other species. On the other hand, phenolic metabolites in rat urine; and tropic acid in rabbit and guinea pig urine, were excreted as the free forms. 6. These results indicate that scopolamine metabolism is highly species-specific.

Animals↗

LDL-apheresis and improvement in the coronary atherosclerosis of familial hypercholesterolemia--correlation of computerized quantitative coronary angiography with autopsy findings.

We have evaluated the effects of LDL-aphereses performed over 15 to 62 months, involving both Double Filtration Plasmapheresis (DFPP) and LDL Adsorbent Plasmapheresis (LAPP), for 5 patients with familial hypercholesterolemia (FH) (1; homozygous, and 4; heterozygous) using computer image analysis by coronary angiography, (CAG). Results by CAG showed that in homozygous FH, 9 (75%) of 12 segments demonstrated no progression, 2 (16.7%) segments showed regression, and only 1 (8.3%) segment showed progression. In heterozygous FH, 27 (81.8%) of 33 segments showed progression, and 6 (18.2%) segments showed regression. Aorto coronary bypass was beneficial with obtained patency in 13 (93%) of the 14 grafts. We also performed an autopsy on one patient, with heterozygous FH who died suddenly probably due to fibrillation. The patient had received long-term LDL apheresis for 6 years and 7 months and had shown angiographic regression. The pathological findings showed no typical or new atheroma, significant cicatrization in the thickened intima and an eccentric thickened wall lesion. The serial angiographic findings together with the pathological findings very clearly support the use of LDL-apheresis for producing "true" regression in coronary atherosclerosis in FH.

Adult↗

Improved on-line thoracic duct drainage for lymphocytapheresis.

Lymphocytapheresis using thoracic duct drainage (TDD) is a recognized technique of extracorporeal immunomodulation for various autoimmune diseases such as rheumatoid arthritis (RA), and its clinical benefit has been reported and generally accepted. Lymphocytapheresis using TDD is very selective for removing lymphocytes (especially helper T-cells) but raises some problems such as hypoproteinemia due to the massive removal of lymph, and difficulties in repeated treatment. Along with the development of a new polyester fiber filter, we have developed a simple and effective method of lymphocytapheresis for wide adoption for these techniques. We performed lymphocytapheresis using TDD in patients with RA and previously reported its clinical efficacy indicated by the significantly lower number of peripheral lymphocytes and T4/T8 ratio. We present here our newly-developed on-line system designed to prevent hypoproteinemia. Furthermore we report on the advantages with a new subcutaneous vascular access device set up to manage the problems of repeated treatments. A small reservoir for keeping the thoracic duct open and returning lymph to the patient permitted sufficient lymph drainage and removal of lymphocytes and the clinical application of TDD is discussed.

Arthritis, Rheumatoid↗

[Cardiopulmonary support in PTCA for severe coronary artery disease: its efficacy].

Percutaneous transluminal coronary angioplasty (PTCA) assisted by cardiopulmonary femorofemoral bypass was performed in 4 patients who were considered to be candidates for this technique because of their severe coronary artery diseases, including 2 with left main trunk disease, one with cardiogenic shock, and one with severe 3-vessel disease. Here we report the efficacy of cardiopulmonary support in PTCA. Case 1: An 85-year-old man with persistent unstable angina despite maximal doses of medications. Stenosis of the left anterior descending coronary artery (90%) was resolved by PTCA with cardiopulmonary bypass and intraaortic balloon pumping (IABP). Case 2: An 83-year-old man with unstable angina had high grade stenoses in the distal left main, left anterior descending and right coronary arteries. Although IABP was instituted for sustained chest discomfort and ST depression, the patient developed congestive heart failure. PTCA of the left main coronary artery with cardiopulmonary bypass was successfully performed. Case 3: A 64-year-old man with acute myocardial infarction. PTCA of the occluded left anterior descending coronary artery resulted in shock despite IABP, which was resolved by cardiopulmonary bypass with percutaneous insertion of cannulae, the technique we developed. Case 4: A 74-year-old man with unstable angina. He had a severe 3-vessel disease and a thrombus in the right coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Intracoronary administration of ergonovine maleate for detecting vasospastic angina; one dose method].

Coronary spasm is an important etiologic mechanism in the pathogenesis of myocardial ischemia. Provocative test of coronary spasm during coronary arteriography is clinically useful. The ergonovine test has gained widespread use, and we have examined the efficacy and safety of intracoronary ergonovine application with a fixed dose of 16 micrograms. We studied 119 patients undergoing coronary arteriography. Coronary spasm was induced in 34 cases by intracoronary administration of 16 micrograms of ergonovine maleate. Coronary spasm was readily resolved by intracoronary administration of isosorbide dinitrate. None of the cases negative to the intracoronary ergonovine applications could be induced by additional systemic administration of 0.4 mg of ergonovine. Side effects of ergonovine such as elevation of blood pressure, headache and chest symptoms were infrequent in the intracoronary ergonovine test. We conclude that our method of intracoronary ergonovine application is sensitive and safe for the diagnosis of coronary spasm.

Aorta↗

[Toxicological assessment of 2,5,2',5'-tetrachlorobiphenyl and its major metabolite, 3-hydroxy-2,5,2',5'-tetrachlorobiphenyl in rats].

We observed previously that polychlorinated biphenyl (PCB) could be classified to two groups, 3-methylcholanthrene (MC)-type and phenobarbital (PB)-type, in term of inducibility of the hepatic enzymes. MC-type PCBs such as 3,4,3',4'-tetrachlorobiphenyl (TCB), 3,4,5,3',4'-pentachlorobiphenyl (PenCB) and 3,4,5,3',4',5'-hexachlorobiphenyl (HexCB) exhibited high acute toxicity in parallel with their induction ability of microsomal benzo[a]pyrene 3-hydroxylase and cytosolic DT-diaphorase. On the contrary, PB-type PCBs such as 2,5,2',5'-TCB and 2,4,5,2',4',5'-HexCB which induce microsomal benzphetamine N-demethylase and NADPH-cytochrome P-450 reductase activities showed virtually no or very low toxicity. In the present study, we examined effects of 2,5,2',5'-TCB and its major metabolite 3-hydroxy-2,5,2',5'-TCB on body weight gain, organ weights and activities of hepatic enzymes in rats and assessed acute toxicity of these compounds. As the results, in both 2,5,2',5'-TCB and 3-hydroxy-2,5,2',5'-TCB groups, the body weights were increased during the experiment, but the rate of growth was significantly suppressed after 3 days. Significant hypertrophy of the liver and decrease of total liver lipid content were observed in 2,5,2',5'-TCB group, but the atrophy of spleen and thymus was not affected in both groups. On the other hand, in 2,5,2',5'-TCB group, benzo[a]pyrene 3-hydroxylase and benzphetamine N-demethylase activities were increased to 2. 4-fold and 1.5-fold, respectively, but were not increased in 3-hydroxy-2,5,2',5'-TCB group. After injection of 2,5,2',5'-TCB, 45% of the dose was excreted as 3-hydroxy-2,5,2',5'-TCB in feces for 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[Acute toxicity, inductive effects of liver enzymes and distribution in the liver of 1,2,3,7,8-pentachlorodibenzo-p-dioxin in rats].

Acute toxicity, inductive effects of liver enzymes and liver persistency of 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PenCDD) were compared with those of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) using male Wistar rats. 1,2,3,7,8-PenCDD treatment at a dose of 0.1 mumol/kg resulted in significant depression of growth of rats from a day to 28 days after treatment. However, the effect was relatively less than that of 2,3,7,8-TCDD. On 5 days, similarly to 2,3,7,8-TCDD-treated group, liver hypertrophy and thymic atrophy were observed in 1,2,3,7,8-PenCDD-treated groups. In addition, 1,2,3,7,8-PenCDD showed potent 3-methylcholanthrene-type inducing ability. For example, the activities of benzo(a)pyrene 3-hydroxylase and DT-diaphorase were 25-fold and 10-fold of control, respectively. On 30 days, about 50% of the inductive effects on 5 days were maintained in both 1,2,3,7,8-PenCDD- and 2,3,7,8-TCDD-treated groups. Amount of 1,2,3,7,8-PenCDD distributed to the liver on 5 days was about 80-90% of dose and was about 1.5 times greater than that of 2,3,7,8-TCDD. About 50% of dose of 1,2,3,7,8-PenCDD remained even on 30 days after treatment. From these results, it is suggested that 1,2,3,7,8-PenCDD possessing the potent acute toxicity comparable to 2,3,7,8-TCDD and higher persistency in the liver might be more important than 2,3,7,8-TCDD in terms of the chronic toxicity.

Animals↗

Purification and characterization of two forms of 2,3,4,7,8-pentachlorodibenzofuran-inducible cytochrome P-450 in hamster liver.

Two forms of cytochrome P-450 (P-450) from liver microsomes of hamsters treated with 2,3,4,7,8-pentachlorodibenzofuran (PenCDF), which possesses the potent acute toxicity and 3-methylcholanthrene (MC)-type inducing ability of liver microsomal monooxygenases in animals, were purified and characterized. These P-450 forms, designated as hamster P-450H and hamster P-450L, had the molecular masses of 52 and 50 kDa, respectively, and showed the absorption maximum of CO-reduced difference spectra at 446 nm. The absolute spectra of their oxidized forms indicated that hamster P-450H was in high-spin state and hamster P-450L was in low-spin state. A part of PenCDF injected into hamster was tightly bound to purified hamster P-450H at a ratio of 0.107 nmol PenCDF/nmol P-450. In a reconstituted system, both hamster P-450H and hamster P-450L showed relatively low catalytic activities for 3-hydroxylation of benzo[a]pyrene and O-deethylations of both 7-ethoxyresorufin and 7-ethoxycoumarin, while they both catalyzed 7 alpha- and 2 alpha-hydroxylations of testosterone effectively to a similar extent. Addition of cytochrome b5-to a reconstituted system accelerated the formation of 7 alpha-hydroxytestosterone 5.3-fold with hamster P-450L and 2.2-fold with hamster P-450H. In addition, hamster P-450H catalyzed estradiol 2-hydroxylation at a high rate but hamster P-450L did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Percutaneous transluminal coronary angioplasty with cardiopulmonary bypass for stenosis of the most proximal part of the left anterior descending coronary artery.

An 85 year old man with unstable angina pectoris was treated successfully with percutaneous transluminal coronary angioplasty supported by cardiopulmonary bypass and intra-aortic balloon pumping. Coronary angiography had shown stenoses in both the left main stem and left anterior descending coronary arteries. Drug treatment had been ineffective and he was too old for coronary arterial bypass grafting.

Aged↗

Metabolism in vivo of 3,4,5,3',4'-pentachlorobiphenyl and toxicological assessment of the metabolite in rats.

Metabolism in vivo of 3,4,5,3',4'-pentachlorobiphenyl (PenCB) and toxicological assessment of the metabolite were investigated using male Wistar rats. Only one metabolite was isolated from the feces of rats administered 3,4,5,3',4'-PenCB. By gas chromatography-mass spectrometry, the methylated metabolite was identified with the synthesized authentic sample, 4'-methoxy-3,4,5,3',5'-PenCB. This indicated that the metabolite was 4'-hydroxy-3,4,5,3',5'-PenCB, which was produced via a 4',5'-epoxide formation and subsequent NIH-shift of the 4'-chlorine to the 5'-position. Administration of the metabolite at either single i.p. dose of 3 or 10 mg/kg to rats did not cause any toxic and biological effects such as body weight loss, atrophy of thymus and spleen, liver hypertrophy, increase of liver lipids, or 3-methylcholanthrene-type induction of liver enzymes. These changes were observed in rats administered with 3,4,5,3',4'-PenCB at a single dose of 3 mg/kg. In addition, a trace amount of 4'-hydroxy-3,4,5,3',5'-PenCB could be detected in rat liver 5 d after treatment with 3,4,5,3',4'-PenCB or 4'-hydroxy-3,4,5,3',5'-PenCB. The amount of this metabolite excreted in feces during 5 d after treatment with 3,4,5,3',4'-PenCB accounted for only 1.3% of dose. In 4'-hydroxy-3,4,5,3',5'-PenCB-treated rats, about 60% of dose was excreted as unchanged in feces for 5 d. These results suggest that this metabolite is a detoxified product and has no longer the high affinity for the liver, being excreted rapidly into the feces.

Animals↗

Rat liver DT-diaphorase as a nitroso-reductase.

Reduction of several nitroso-compounds by purified DT-diaphorase from rat liver cytosol was investigated. Among nitroso-compounds tested, 1-nitroso-2-naphthol and p-nitrosophenol were reduced in the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH) at rates much faster than that of nitrosobenzene. On the contrary, none of the N-nitroso-compounds tested was reduced by this enzyme. Experiments on the identification of reduction products and on the inhibition with dicoumarol and the antiserum indicated that DT-diaphorase catalyzes 4-electron reduction of C-nitroso-compounds and plays a major role in the reduction of these compounds by rat liver cytosol.

Animals↗

Further studies on metabolism in vivo of 3,4,3',4'-tetrachlorobiphenyl in rats: identification of minor metabolites in rat faeces.

1. Metabolism in vivo of 3,4,3',4'-tetrachlorobiphenyl (TCB) was investigated in male Wistar rats. 2. Five new minor metabolites in addition to two previously identified major metabolites (5-hydroxy-3,4,3',4'-TCB and 4-hydroxy-3,5,3',4'-TCB) were isolated as methylated derivatives from faeces of rats treated with 3,4,3',4'-TCB, by silica gel column chromatography and subsequent preparative t.l.c. 3. Among these methylated metabolites, three were identified as dimethoxy-TCB, and one as monomethoxy-trichlorobiphenyl (TriCB), by g.l.c.-mass spectrometry. By comparison with synthetic standards they were fully identified as 2,5-dimethoxy-3,4,3',4'-TCB, 4,4'-dimethoxy-3,5,3',5'-TCB, 5,6-dimethoxy-3,4,3',4'-TCB, and 4-methoxy-3,3',4'-TriCB, respectively. The structures of these metabolites in rat faeces should therefore be 2,5-dihydroxy-3,4,3',4'-TCB, 4,4'-dihydroxy-3,5,3',5'-TCB, 5,6-dihydroxy-3,4,3',4'-TCB, and 4-hydroxy-3,3',4'-TriCB. 4. One further metabolite was isolated, which was shown to be an oxepin, existing in a state of equilibration with the 4',5'-oxide of the major metabolite, 4-hydroxy-3,5,3',4'-TCB, by mass and 1H-n.m.r. spectra. On standing for several months, this metabolite isomerized to a new compound with a different g.l.c. retention time, which on methylation yielded a product identical with synthetic 4,4'-dimethoxy-3,5,3',5'-TCB by g.l.c.-mass spectrometry. From these results this metabolite was assumed to be an oxepin, equilibrated with 4-hydroxy-4',5'-epoxy-3,5,3',4'-TCB.

Animals↗