Biomedical subjects

M Koga

Publications and source records attributed to M Koga.

At least 307 records · Page 17Linked to original sources

PubMed1993

Colonic submucosal tumors: a new classification based on radiologic characteristics.

OBJECTIVE: Despite advances in gastrointestinal radiologic techniques, findings from barium enema studies cannot be used reliably to predict the histologic nature of a colonic submucosal tumor. Therefore, we generated a new and comprehensive classification system for all colonic submucosal tumors based on a correlation between their radiologic characteristics and their histopathologic features. MATERIALS AND METHODS: Between 1978 and 1990, 89 patients had 95 colonic submucosal tumors diagnosed on the basis of barium enema studies and confirmed by biopsy or surgery. Of these, 39 patients (44%) were symptomatic and 50 patients (56%) were asymptomatic. Single lesions (82 cases) and multiple lesions (12 cases of lymphoma and one case of blue rubber bleb nevus) were observed. The 95 lesions included 21 carcinoids, 27 malignant lymphomas, 17 lipomas, 10 lymphangiomas, six leiomyosarcomas, five leiomyomas, and nine others. We analyzed the radiologic findings and classified these lesions according to their appearance. RESULTS: All tumors were classified on the basis of their morphologic appearance into five types: (1) wide-based sessile lesion with gradually sloping margin and smooth surface (17 cases); (2) wide-based sessile lesion, more polypoid than the first type, with a smooth surface, with or without a central depression (49 cases); (3) wide-based sessile lesion with lobulated surface (six cases); (4) pedunculated lesion with smooth or granular surface (17 cases); (5) unclassified, not any of the previously mentioned types, may be diffusely stenotic or aneurysmal (six cases). The most common finding was the wide-based sessile lesion with a smooth surface and a possible central depression; next most common was the wide-based sessile lesion with gradually sloping margin and smooth surface; next was the pedunculated lesion with a smooth or granular surface. Eighty-six percent of the lesions were single; 14% were multiple. Histologic confirmation revealed mainly lymphoma (29%) and carcinoid (22%), of which the most common finding was a wide-based sessile lesion with a smooth surface, with or without a central depression. CONCLUSION: This new classification based on radiologic characteristics covers all varieties of colonic submucosal tumors. It can serve as a guideline for predicting a specific diagnosis of a colonic submucosal tumor on the basis of radiologic findings.

Adolescent↗

PubMed1993

Brain energy metabolites in mice after an acute exposure to carbon monoxide.

Brain energy metabolites were determined in mice over 8 days after an acute exposure to carbon monoxide (CO). The exposure of 0.5% CO for 15 min caused 33% mortality. Survived mice recovered completely within 30 min in room air. Lactate increased markedly immediately after the exposure, while glucose increased 30 min later. Four hours, 1 day, 4 days and 8 days after the exposure, the levels of brain energy metabolites including phosphocreatine and ATP did not differ from those of the control. Thus, energy metabolism in the whole brain in mice appears not to be impaired after they survive an acute CO intoxication.

Adenosine Triphosphate↗

PubMed1993

The synthesis of alternating alpha,beta-oligodeoxyribonucleotides with alternating (3'-->3')- and (5'-->5')-internucleotic linkages as potential therapeutic agents.

A simplified synthesis of alpha-2'-deoxyribonucleoside derivatives has been developed and the solid-phase preparation of antisense alpha,beta-oligodeoxyribonucleotides with alternating (3'-->3')- and (5'-->5')-internucleotidic phosphodiester linkages, targeted against HIV-1 tat mRNA, has been accomplished. Hybridization properties of these oligonucleotide analogues have been investigated.

Base Sequence↗

PubMed1993

Oligonucleotides of carbocyclic 5'-nor 2'- and 3'-deoxyadenosine.

Oligonucleotides possessing a shortened internucleotide bond have been prepared using carbocyclic nucleosides lacking the 5'-methylene as the monomeric units. Specifically, the oligomers derived from 5'-nor carbocyclic 2'-deoxyadenosine and 3'-deoxyadenosine will be described.

Cyclopentanes↗

PubMed1993

[Molecular mechanism of androgen-dependent transformation--analysis using serum-free culture system].

SC-3 cells, derived from androgen-dependent mouse breast cancer Shionogi carcinoma 115, have shown not only androgen-dependent growth stimulation but also morphological changes in serum-free culture. We have demonstrated that this androgen-dependent growth is mediated through an induction of heparin-binding growth factor (termed as androgen-induced growth factor: AIGF). We studied the molecular mechanism of androgen-dependent growth. NIH3T3 cells transfected to express AIGF showed focus-forming activity, anchorage-independent growth and tumor formation in nude mice indicating AIGF is an oncogene. The findings that AIGF inhibited binding of [125I]basic fibroblast growth factor (bFGF) and only FGF receptor (FGFR)-1 mRNA expressed in SC-3 cells suggested that AIGF acts through FGFR-1. Therefore, we cloned FGFR-1 from cDNA library of SC-3 cells, which was found to have three mutations. When this variant FGFR-1 was expressed in FGFR-negative myoblast L6 cells, AIGF-dependent inhibition of the differentiation to myocytes was observed suggesting that variant FGFR-1 is receptor of AIGF. Since expressions of c-myc mRNA as well as AIGF mRNA were induced by testosterone treatment, we studied the role of c-myc in androgen-dependent growth in SC-3 cells using phosphorothioate derived antisense oligonucleotides (antisense) of c-myc or AIGF. Not only AIGF antisense but also c-myc antisense inhibited androgen-dependent growth. c-myc antisense did not affect androgen-induced AIGF mRNA expression. c-myc antisense inhibited AIGF-, but not bFGF-induced DNA synthesis. These results suggest that c-myc has a critical role of AIGF-, but not bFGF-induced growth.

3T3 Cells↗

PubMed1992

(+-)-carbocyclic 5'-nor-2'-deoxyguanosine and related purine derivatives: synthesis and antiviral properties.

Beginning with 3-cyclopenten-1-ylamine hydrochloride, the 5'-nor derivatives of carbocyclic 2'-deoxyguanosine (2), 2'-deoxyadenosine (3), and 2,6-diaminopurine 2'-deoxyribofuranoside (4) have been prepared. These compounds were evaluated for antiviral potential versus herpes simplex virus, varicella-zoster virus, cytomegalovirus, vaccinia virus, vesicular stomatitis virus, and human immunodeficiency virus and found to lack activity. Also, compounds 2-4 were virtually nontoxic toward the host (human diploid fibroblast ESM and HEL) cells. These biological properties may be due to the inability of 2-4 to be phosphorylated to the requisite nucleotide level that is likely to be necessary for biological activity by correlation to carbocyclic 2'-deoxyguanosine (1), which possesses significant antiviral properties as a result of conversion to its 5'-triphosphate derivative.

2-Aminopurine↗

PubMed1992

Identification and quantitative analysis of urinary metabolites of dichloropropanols in rats.

Urinary metabolites of dichloropropanols in rats were analyzed by gas chromatography-mass spectrometry (GC/MS). Solutions of dichloropropanols consisting of 1, 3-dichloro-2-propanol (DC2P) and 2, 3-dichloro-1-propanol (DC1P) were diluted in a saline at the concentration of 100 mg/ml, and 0.1 ml of the solutions were subcutaneously injected into male Wistar rats weighing about 160g. The urine samples were collected over a period of 24 hours after the injections. DC2P and DC1P in the urine were extracted with ethylacetate and analyzed by a GC/MS. The derivatization procedure with 4-bromophenylboric acid after acetonitril extraction was applied for the analyses of diols in the urine. By the GC/MS analysis, 3-chloro-1, 2-propanediol (3CPD), 2-chloro-1, 3-propanediol (2CPD) and 1, 2-propanediol (PPD) were identified as the hydroxylated metabolites of dichlorpropanols. Based on the analytical results, the metabolic pathways of dichlorpropanols forming 3CPD and 2CPD, and then hydroxylating to PPD were elucidated.

Animals↗

PubMed1992

[Fulminant hepatitis after the inhalation of dichloropropanols].

A fatal case of acute fulminant hepatitis following exposure to dichloropropanols is reported. A 59-year-old male worker in a chemical plant developed general malaise, nausea and vomiting several hours after cleaning a tank that had contained dichloropropanols. He had no previous history of hepatic dysfunction. On admission, hepatomegaly was prominent. Because of highly elevated levels of GOT and GPT in the serum, reduced prothrombin time and a lowered consciousness level, a diagnosis of fulminant hepatitis was made. Significant decreases of leukocytes and platelets were also observed. Serum creatinine and BUN were slightly elevated. Although plasma exchanges were conducted on the third and fourth day, the liver functions continued to deteriorate. The patient died on the fifth day. Because dichloropropanols could be detected in the blood specimens obtained at the time of admission, we considered that fulminant hepatitis in this case was attributed to dichloropropanols exposure. To our knowledge, this is the first case of fulminant hepatitis after dichloropropanols-exposure.

Administration, Inhalation↗

PubMed1992

[Toxicity of dichloropropanols--changes in hematological findings and serum chemistry].

We investigated the toxicity of dichloropropanols (DCPs) in hematological findings and serum chemistry. The solutions of two isomers of DCPs, 1,3-dichloro-2-propanol (DC2P) and 2,3-dichloro-1-propanol (DC1P) were dissolved in saline at the concentration of 100 mg/ml, and 0.1 ml of each solution was subcutaneously injected into male Wistar rats weighing about 200 g. At 6 hours after the injections, in the DC2P group, the number of white blood cells and platelets showed a significant decrease. Transaminases, alkaline phosphatase and lactate dehydrogenase were greatly elevated. Blood urea nitrogen and creatinine also showed a significant increase. There were no changes in the measurements in the DC1P group. These results indicate that there is a prominent hepatotoxicity in DC2P, and that there is a considerable difference in the toxicity present in DC2P and DC1P. Furthermore, in the workplace where DCPs, especially DC2P, is used, the monitoring of the working environment and biological monitoring should be mandatory.

Alkaline Phosphatase↗

PubMed1992

Complete correction of the tetralogy of Fallot in adults using separated extracorporeal circulation to block intrathoracic collateral circulation and improve perfusion of the renal vasculature.

During the last 10 years, complete correction of the tetralogy of Fallot (TOF) has been performed on 28 adult patients using the "separated extracorporeal circulation" (separated ECC) technique developed by us. In addition to the usual ascending aortic and dual right arterial cannulations for ECC, the separated ECC also involved femoral arterial cannulation and the insertion of a catheter with two balloons via the other femoral artery. Flow via the ascending aorta and femoral artery were maintained separately during ECC. The urine output during separated ECC was significantly better than that during ordinary ECC (P < 0.01) and the operative field for intracardiac correction was clearer as a result of blocking the collateral circulation. Thus we believe separated ECC to be a superior method for total correction of TOF in adults, which may enhance the operative outcome.

Adult↗

PubMed1992

Active and inactive renin after exercise.

The effects of graded exercise on plasma concentrations of active and inactive renin were studied in seven healthy men. Exercise was performed on a cycle ergometer at four different exercise intensities (corresponding to 30%, 50%, 80% and 87% of VO2max) for 10 min each. Concentrations of active renin and total renin after activation by trypsin were measured by direct immunoradiometric assay. Non-trypsin-activated renin concentration (inactive) was obtained by subtraction. Active renin concentrations at 30%, 50%, 80% and 87% of VO2max were 1.2, 1.9, 3.1 and 4.6 times higher than the control concentration, respectively. Similar increases in plasma renin concentration, determined by conventional enzymatic assay, were observed at every stage. In contrast, changes in inactive renin concentration were not significant at any stage. Significant increases in noradrenaline concentration were found at every exercise stage, but adrenaline, aldosterone and lactate concentrations were significantly elevated only after exercise at 50%, 80% and 87% of VO2max. The similarity between the changes in concentration of active renin and noradrenaline would suggest that sympathetic nerve activity may have been responsible either for the release of active renin or for the conversion of inactive renin to its active form in the kidney.

Adult↗

PubMed1992

Farber bodies found in murine phagocytes after injection of ceramides and related sphingolipids.

Mice were injected subcutaneously with a single dose of sphingolipids. The sphingolipids tested were: ceramide with alpha-hydroxy fatty acids, ceramide with non-hydroxy fatty acids, glucocerebroside, sphingomyelin, and galactocerebroside. Lipids without sphingolipids served as a control. The mice were sacrificed 1, 2, 3, 4, 5 and 7 days after injection. Three mice were used for each experiment. The subcutaneous tissue at the injected area, the liver and the spleen were studied histologically. At 1-3 days after injection, numerous cytoplasmic inclusion bodies were observed in the macrophages and fibroblasts in the subcutaneous tissue, but not in the liver or the spleen. Ultrastructural studies of the inclusion bodies indicated that the sphingolipids taken up by the phagocytes retained their respective original shape during the 1-3 day stage. At days 4 and 5, the number of the inclusion bodies decreased, but they contained Farber bodies, i.e. curvilinear bodies 12 to 25 nm wide and up to 120 nm long. The mice with galactocerebroside were an exception, with parallel leaflets structures, but without the Farber bodies.

Animals↗

PubMed1992

Using microparticle labeling and counting for attomole-level detection in heterogeneous immunoassay.

A new heterogeneous "sandwich" immunoassay utilizing microparticles as labels to realize high sensitivity is described. In this method, antibody fixed on the microparticles reacts with antigen previously trapped on a microplate surface, which makes the antigen molecules visible and countable with an inverted optical microscope. The method is highly sensitive because the reacted single microparticle, therefore single antigen molecule, can be detected. The sensitivity depends both on the reaction efficiency of the immunoreaction and on nonspecific adsorption of the microparticles on the microplate surface. Therefore, the protocol for preparing microparticle having antibody on the surface and a microplate having capture antibody was investigated to realize high sensitivity. Carboxylated microparticles of 0.76 microns in diameter were conjugated with affinity-purified antibody using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. It was determined that 1 g microparticles had 880 micrograms antibody (approximately 1100 antibody molecules per 1 microparticle). The immunoreaction efficiency reached 18% at 1 x 10(-13) mol/liter antigen concentration. The lower detection limit was 3.1 x 10(-14) mol/liter (1.6 amol) using human alpha-fetoprotein as a model antigen.

Adsorption↗

PubMed1992

Comparison of hepatitis C virus markers in patients with NANB hepatitis.

10 different HCV-specific assays and RT-PCR of the 5' untranslated region of HCV RNA were used to analyze sixty-four patients with chronic NANB liver disease. Po, CP-9 and C22 antigens are located in the putative core; C33c in the putative NS3; C100-3 in the putative NS3/4; KCL in the putative NS4/5 and C825 is located in the putative NS5. GOR protein is not part of the HCV genome, but antibodies to it appear to be present in response to a hepatitis C infection. Positive rates were 91% for Po, 89% for CP-9, 94% for C22, 97% for C33c, 88% for C100-3 (Ortho, EIA), 86% for C100-3 (Abbott, EIA), 84% for C100-3 (Ohtsuka, RIA), 88% for KCL, 59% for C825, 58% for GOR, and 83% for RT-PCR. There were 8 cases which were negative by all anti-C100 tests. 7 of these cases were positive by other anti-HCV markers and/or PCR suggesting the need for improved blood screening assays. There is a variation in the relative reactivity for different markers with different samples. Of the tests employed, anti C33c shows the highest positivity rate.

Adult↗

PubMed1992

Effects of retinoic acid on estrogen- and thyroid hormone-induced growth in a newly established rat pituitary tumor cell line.

In order to elucidate the complex mechanism(s) of action of steroid hormones, thyroid hormone and retinoic acid in pituitary mammotrophs, a clonal cell line (G3) was isolated from the rat pituitary tumor MtT/F84. G3 cells were found to secrete prolactin constitutively and to contain receptors for estrogen, glucocorticoid, progesterone and thyroid hormone. Stimulation of G3 cells with thyroid hormone resulted in a modest but significant increase in estrogen and progesterone receptor levels, however, retinoic acid treatment had no effect. Simultaneous addition of thyroid hormone and estrogen showed an additive effect on progesterone receptor levels in G3 cells. Thyroid hormone as well as estrogen enhanced the growth of G3 cells. Interestingly, retinoic acid was also found to enhance their growth but its enhancement was less potent than thyroid hormone and estrogen. Low concentrations of estradiol and thyroid hormone showed additive effects, but G3 cells stimulated with high concentrations of thyroid hormone failed to elicit an additive effect with estrogen, suggesting the presence of a common pathway in the growth-stimulatory actions of these hormones. In addition, exposure of G3 cells to retinoic acid completely abolished the effects of estrogen or thyroid hormone in terms of cell growth. These results suggest that there are complex interactions in the signalling pathways for estrogen, thyroid hormone and retinoic acid action in G3 cells.

Animals↗

PubMed1992

Influence of workload on the antihypertensive effect of exercise.

1. The relation between workload and the antihypertensive effect of exercise therapy in hypertensive patients, and the mechanism of that effect, were investigated. 2. Twenty-six patients participated in the study and were randomly assigned to 10 weeks of either low or high workload exercise. In the low workload group, 16 mild hypertensive patients were treated with bicycle ergometer exercise at approximately 50% of their maximum oxygen consumption (VO2max) for 60 min three times a week for 10 weeks. In the high workload group, 10 mild hypertensive patients exercised on the same schedule, but at approximately 75% of VO2max. 3. After 10 weeks of exercise, the low workload group had significantly lower systolic (9 mmHg), mean (6 mmHg) and diastolic (6 mmHg) blood pressures. In the high workload group, decreases in systolic (3 mmHg), mean (4 mmHg) and diastolic (5 mmHg) blood pressure were not statistically significant. 4. In the low workload group, changes in haemodynamic and humoral variables were not significant, except for a reduction in plasma norepinephrine at week 7. Cardiac index and plasma norepinephrine tended to decrease. In the high workload group, plasma norepinephrine and the renin-angiotensin system were transiently stimulated after 4 weeks of exercise. Stroke volume significantly increased (+26.4%) after 10 weeks of high workload exercise. 5. Based on these results and better patient compliance with the exercise programme in the low workload group than in the high workload group, low workload exercise therapy was recommended to mild hypertensive patients.

Adult↗

PubMed1992

An autopsy case of Farber's lipogranulomatosis in a Japanese boy with gastrointestinal involvement.

A boy with Farber's lipogranulomatosis is reported. Excessive ceramide was revealed by thin-layer chromatography of the extracts from the liver. Acid ceramidase activity of the liver was 31.5% of control with exogenous substrate and 33.3% without exogenous substrate. The histological appearance showed granulomatous lesions, composed of spindle or oval-shaped storage cells and proliferation of the connective tissues, in the subcutaneous tissue of the lower lip, periarticular regions and the pericardium. Histochemically the storage cells were revealed to contain lipid and polysaccharide. The foreign body granuloma formed by the surgical suture in the liver was surrounded by a large number of foamy cells. In gastrointestinal mucosa widespread erosion, disappearance of glands and abundant collagen fibers were noted. On electron microscopy, the spindle or oval-shaped cells in the subcutis of the lip had intracytoplasmic inclusions containing granular or fibrillar materials and a smaller number of curvilinear structures, so called "Farber bodies". Our case was a typical clinical and histopathological presentation of Farber's lipogranulomatosis. However, ceramidase activity was higher than in previous descriptions, and severe gastrointestinal lesions and the appearance of a large number of foamy cells around the foreign body granuloma have not been described previously.

Acid Ceramidase↗

PubMed1992

A case of Farber disease.

We report a case of Farber disease (Farber lipogranulomatosis). The main features were a shrill voice, joint swelling, subcutaneous nodules and retarded psychomotor development. Cytological investigation revealed intracytoplasmic inclusion bodies characteristic of Farber disease. Lipid analysis of liver tissue indicated an accumulation of ceramide containing non-hydroxy fatty acids. It was found that the acid ceramidase activity in the liver was reduced to 31% of the control value. In this patient there was also persistent diarrhea, cholelithiasis, transient proteinuria and increased urinary total sialic acids. These features have not been noted in previously reported cases.

Acid Ceramidase↗