Biomedical subjects
Publications and source records attributed to Y Imamura.
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The influence of aging on the reductase activity of acetohexamide, an oral antidiabetic drug with a ketone group, was examined in liver microsomes and cytosol of male rats. Acetohexamide reductase activities in liver microsomes of male rats at 26 and 31 months of age were much lower than that in liver microsomes of male rats at 9 weeks of age. Testectomy markedly decreased acetohexamide reductase activity in liver microsomes of the 9-week old rats and the decreased enzyme activity was significantly increased by testosterone administration. These results indicate, at least in part, that aging decreases the enzyme activity by decreasing the secretion of testosterone from the testes. On the other hand, aging (26 months of age) did not affect acetohexamide reductase activity in liver cytosol of male rats, although the enzyme activity at 31 months of age was slightly but significantly lower than that in liver cytosol of male rats at 9 weeks of age. Testectomy or testosterone administration had no effect on the enzyme activity in liver cytosol of 9-week old male rats.
A rare case of radiologically occult lung cancer in the peripheral region beyond bronchoscopic visibility is reported. A 69-year-old female was referred because of positive sputum cytology. Despite detailed bronchoscopic and otorhinoralyngologic examinations, the source of malignant cells was not localized. During the follow-up period, squamous cell carcinoma of the lung periphery was detected radiologically three years after its presence was detected in sputum. Awareness of the existence of this type of cancer and careful follow-up are important in the management of patients with positive sputum cytology and no evidence of cancer.
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The degree of DNA-instability as revealed by the immunohistochemical staining with monoclonal anti-single-stranded DNA antibody after acid hydrolysis (DNA-instability test) was used as the marker of malignancy. This was applied to human gastric regenerative epithelium in chronic peptic ulcer (5 cases), adenoma (35 cases), and well differentiated tubular adenocarcinoma (5 cases). Proliferative activity was evaluated by proliferating cell nuclear antigen (PCNA) immunohistochemistry, and the quantitative analyses of the mean number and mean area of silver-stained nucleolar organizer regions (AgNORs) per one nucleus were performed for all these cases. All cancers and adenomas were positively stained by the DNA-instability test diffusely, indicating the malignant character of the latter from the view point of DNA-instability, in contrast to the negative stainability of all regenerative epithelium. The percent number of PCNA-positive cells and mean number and mean area of AgNORs tended to be larger in adenoma and cancer than in regenerative epithelium, although the differences were not usually statistically significant. Supporting the malignant character of adenoma, single cell necroses and abnormal mitoses were almost always present in the lesion. In conclusion, all adenoma lesions were regarded as malignant in nature, namely, in-situ carcinoma, existing at an early stage of progression of malignancy.
The degree of DNA-instability as revealed by the immunohistochemical staining with anti-single-stranded DNA antibody after acid hydrolysis (DNA-instability test) was used as a marker of malignancy. This was applied to benign, border-line, and malignant neoplastic lesions found in the otorhinolaryngeal regions (31 cancer, 22 leukoplakia, 10 nasal inverted papilloma, 33 salivary gland pleomorphic adenoma, and 7 Warthin's tumor cases). Proliferative activity and polarity of the proliferative cell distribution were evaluated by PCNA-immunohistochemistry, and the quantitative analyses of the number, mean size, largest size, and maximum shape-irregularity of AgNORs in a nucleus were performed for all these cases. As the results, 31 cancer (100%), 20 leukoplakia (90.1%), 10 nasal inverted papilloma (100%), and 21 pleomorphic adenoma (63.6%) cases were positively stained by the DNA-instability test diffusely or sporadically, indicating their malignancy. Reflecting the malignant character, these cases showed a remarkable increase in the PCNA-index with the loss of polarity of PCNA-positive cell distribution, and also increased number, mean and largest sizes, and maximum shape-irregularity of AgNORs. These results indicate that all nasal inverted papillomas are malignant in nature, namely, in situ carcinoma, and the majority of leukoplakia is also regarded as in situ cancer, although a certain percentage of simple hyperplasia may be included. Furthermore, the pleomorphic adenoma of the salivary gland can be regarded as an "unstable tumor" which often contains or predisposes to bear malignant subclones with occasional capsular or extracapsular invasion, reflecting the progression of malignancy. In the present study, no sign of malignancy was detected in Warthin's tumor.
The influence of testosterone treatment on acetohexamide reductase activities in liver microsomes and cytosol of female rats was examined. Acetohexamide reductase activity in liver microsomes was much lower in female rats than in male rats. Combined testosterone treatment in pubertal and adult periods induced male-specific acetohexamide reductase activity in liver microsomes of female rats. However, testosterone treatment only during puberty or during adulthood was without effect. Testosterone secreted from the testes during puberty appeared to have a significant effect similar to neonatal imprinting in the induction of acetohexamide reductase activity in liver microsomes of female rats. The combined testosterone treatment, or testosterone treatment only during puberty or during adulthood had no effect on acetohexamide reductase activity in liver cytosol of female rats.
To evaluate the feature of the phagocytic cell functions against surgical intervention, the author analyzed superoxide production and Mac-1 expression of peripheral polymorphonuclear leukocytes (PMN), cytokine production (IL-1 beta, TNF alpha) of peripheral monocyte (Mo) and peritoneal macrophage (M phi) in 35 surgical patients. The ability of PMNs in superoxide anion production and the level of Mac-1 expression on PMNs increased within 24 hr after operation. Those changes synchronized that of Mo to produce IL-1 and TNF increased after operation and peaked at 1 POD. And L-1 and TNF production of peritoneal M phi increased and peaked at 8 hr after operation. However, both IL-1 and TNF could not be detected in their sera of all patients. These findings disclosed that the surgical injury might induce in vivo activation of local M phi and circulating Mo, and priming of the PMN by activated M phi and due to their producing cytokines such as IL-1, TNF and G-CSF. It might be, therefore, concluded that these reactions of the phagocytic cells may be one of the host defense mechanisms against surgical injury.
A correlation was observed between the values of specificity constant (kcat/Km) of carbonyl reductase from rabbit liver for acetohexamide analogs and their partition coefficients. This result indicates that the hydrophobicity in straight-chain alkyl groups of acetohexamide analogs plays an important role in the catalytic activity and substrate-binding capacity of the enzyme. Furthermore, the double logarithmic plots of kcat/Km values of the enzyme for 4-acetylpyridine analogs with a straight-chain alkyl group up to five carbon atoms against their partition coefficients gave a straight line. On the other hand, the plots for 4-acetylpyridine analogs with a straight-chain alkyl group over five carbon atoms and with a branched-chain alkyl group were away from the straight line. It is reasonable to postulate that a hydrophobic pocket is located in the substrate-binding domain of the enzyme.
From January 1988 until December 1990, 99 previously untreated patients with multiple myeloma (MM) were enrolled in a randomized prospective study comparing two combination chemotherapies with and without MCNU as induction therapy for MM; 49 patients with vindesine, melphalan and prednisolone (VMP therapy) versus 50 patients with MCNU, vindesine, melphalan and prednisolone (MCNU-VMP therapy). Seventy-two evaluable patients (34 patients in the VMP group, 38 in the MCNU-VMP group) were analyzed. The response rate was slightly higher with MCNU-VMP than with VMP (81.6% vs. 64.7%). In 43 responders (21 patients in the VMP group and 22 in the MCNU-VMP group) who were treated with the same regimen as the induction therapy to maintain remission, the remission duration was significantly longer in patients treated with MCNU-VMP than in those treated with VMP (median > 10.1 vs. 8.0 months, P = 0.018), particularly in patients with PS 3-4. The remission duration in the MCNU-VMP group was also slightly longer in the patients with stage III disease and who were older than 65 years. The median survival time showed no significant difference between the VMP group (20.3 months) and the MCNU-VMP group (> 15 months). Leukopenia, thrombocytopenia and nausea/vomiting were found to be somewhat severe in the MCNU-VMP group. In summary, MCNU-VMP therapy is effective as induction therapy for MM.
The inhibitory effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the reduction of acetohexamide catalyzed by carbonyl reductase from rabbit kidney were examined. Of NSAIDs tested, only carprofen exhibited a pronounced stereoselectivity for the inhibition of the purified enzyme; (-)-carprofen inhibited more strongly the enzyme than three fold of its (+)-form. (-)-Carprofen was found to inhibit the enzyme noncompetitively with respect to acetohexamide and competitively with respect to NADPH. Similar modes were observed for the inhibition of the enzyme by (+)-carprofen. The treatment of the apoenzyme with (-)-carprofen led to a time- and concentration-dependent loss of the catalytic activity. Furthermore, NADP+ afforded a significant protection against inactivation of the enzyme by (-)-carprofen. These results suggest that enantiomers of carprofen bind to coenzyme-binding domain of the enzyme and cause the stereoselective inhibition of acetohexamide reduction by competing with NADPH.
We have applied DNA flow cytometric analysis to paraffin-embedded tissue sections of primary malignant melanomas. Conventionally, flow cytometric analysis of paraffin-embedded tissue sections has been done by the method of Hedley et al. We added ultrasound treatment to the method of Hedley et al. and a lower value of coefficient of variation was shown. Furthermore, a new technique, fluorescence in situ hybridization with a chromosome-specific repetitive DNA probe, was used for the analysis of chromosomal numerical aberrations in the same paraffin-embedded tissue sections. The DNA flow cytometric analysis showed that in 8 cases six primary malignant melanomas were of the aneuploid pattern and two cases of lentigo maligna (melanoma in situ) were of the diploid pattern. By fluorescence in situ hybridization, the two cases with the diploid pattern had spots/nucleus of 1.28 and 1.12, and those with the aneuploid pattern had spots/nucleus from 2.01 to 2.27. Only one nodular melanoma in an aneuploid case showed spots/nucleus of 1.71. These data indicate that fluorescence in situ hybridization with chromosome-specific repetitive DNA probes can serve as a cytogenetic tool for the analysis of interphase nuclei of solid human tumors and may be useful for the study of tumor cell heterogeneity.
The N-myc gene is amplified and overexpressed in neuroblastoma, retinoblastoma and small cell lung carcinoma, and is considered to be related to cell proliferation and/or differentiation. The transcriptional regulatory sequences of the c-myc gene have been already identified, while those of N-myc have remained obscure for a long time. In this report, we have identified several positive and negative transcriptional regulatory elements in the upstream region of the mouse N-myc gene. Among them, an activating sequence spanning -860 to -797 bp (63 bp) could be reduced to a functional core of 21 bp from -846 to -826. This sequence, termed N21 box, worked as a positive transcriptional element when linked directly upstream (but not downstream) of the putative N-myc promoter in HeLa, not in IMR32 cells. At least two proteins, of 42 kDa and 100 kDa, bound to the double-stranded N21 box, and were expressed in HeLa as well as in IMR32 cells. Moreover, the plus strand of N21 box could be specifically bound by a species of 42 kDa from either cell type and by a 37 kDa protein found only in HeLa cells. These proteins may be factors binding to positive transcriptional regulatory elements and may have a role in the regulation of N-myc expression.
Experimentally induced scoliosis was investigated in pinealectomized chickens using pathologic and neurophysiologic means. A total of 90 chickens were tested; 30 served as a normal control, 30 received an autografted pineal body in the intramuscular tissue of the trunk, and 30 underwent pinealectomy without autograft. Scoliosis developed in all pinealectomized chickens within 2 weeks, showing gradual progression during the next 5 or 6 weeks. At 3 months, the three-dimensional spinal deformity consisted of lateral curvature and vertebral body rotation, resulting in a prominent lordoscoliosis at the thoracic level. In contrast, scoliosis developed in only 10% of the autografted chickens. Histologic examination revealed no pathologic change in the brain in either the pinealectomized scoliosis group or in the autografted nonscoliosis group. Cortical potentials in the scoliosis group were delayed, thus suggesting conduction disturbance rostral to the brain stem. Although the relationship between the cause and effect is uncertain, these findings implicate neurotransmitters or neurohormonal systems in the pineal body as a major contributing factor in this type of experimental scoliosis.
The kinetic mechanism for the reduction of acetohexamide catalyzed by carbonyl reductase from rabbit kidney was investigated. The initial velocity and product inhibition studies indicated that the enzymatic reaction follows an ordered Bi Bi mechanism, in which NADPH binds to the enzyme first and NADP leaves last. This kinetic mechanism was confirmed on the basis of the dead-end inhibition by Cibacron Blue and the binding of NADPH and NADP to the free enzyme. However, whether or not coenzyme-induced isomerization is involved in the enzymatic reaction remains to be clarified. In kinetic studies of inhibition of the enzyme by therapeutically active drugs, indomethacin and befunolol were found to be noncompetitive and competitive inhibitors, respectively, with respect to acetohexamide.
An enzyme catalyzing the metabolic reduction of acetohexamide, an oral antidiabetic drug, has been purified from the cytosolic fraction of rabbit kidney to apparent homogeneity by various chromatographic techniques. The purified enzyme consists of a single polypeptide chain with a molecular weight of 28,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme requires NADPH as a cofactor and has an optimal pH of 6.0. A variety of xenobiotic carbonyl compounds including acetohexamide are effectively reduced by the enzyme. Flavonoids (quercetin and quercitrin) are potent inhibitors for the enzyme, but pyrazole or barbiturates have little effect on the enzyme activity. These findings clearly indicate that the enzyme can be classified as one of the carbonyl reductases. The enzyme also shows both prostaglandin 9-ketoreductase and 3 alpha-hydroxysteroid dehydrogenase activities. Judging from the Kcat/Km values of the enzyme for 4-pyridylketones with a straight-chain alkyl group, a hydrophobic pocket that binds most strongly to a straight-chain alkyl group of five carbon atoms in length appears to be located in the substrate-binding region of the enzyme.
We investigated the production of staphylococcal enterotoxin (SE) with respect to coagulase types by methicillin-resistant Staphylococcus aureus (MRSA). A total of 138 strains of MRSA, which were isolated from clinical materials in the surgical ward between 1983 and 1990, were studied. Coagulase type IV strains produced SE A only, whereas coagulase type II strains were classified into four groups by SE production: SE B producing strains (32.7%), SE C producing strains (29.8%), SE B and C coproducing strains (12.5%), and SE A and C coproducing strains (25.0%). Almost all of the organisms (nine of ten) which were isolated from the feces of patients with MRSA enteritis were SE A and C coproducing strains. The coincidence in time of the prevalence of MRSA enteritis and the isolation SE A and C coproducing strains also demonstrated that these strains caused MRSA enteritis. Although SE C producing strains and SE A and C coproducing strains were simultaneously prevalent in 1990, the former tended to be sensitive while the latter tended to be resistant to minocycline. Considering the variety of antibiotic sensitivity in coagulase type II strains, it is thus considered to be of critical importance for epidemiologic purposes to further characterize isolates by SE typing.
A 24-year-old patient had symptoms of lethargy, convulsions and hyperammonaemia during valproic acid therapy. Cessation of valproic acid treatment brought about an improvement both of the symptoms and of the hyperammonaemia. However, enzymatic analysis after the cessation of valproic acid therapy revealed a complete absence of carbamoylphosphate synthetase (CPS) activity in liver biopsy. A unique polypeptide band, corresponding to the control CPS protein in molecular weight ('CPS-like' protein), was found in normal amounts in the patient's liver on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. This CPS-like protein seemed to be more labile than the control, because the polypeptide band became faint after freeze-thawing. Intravenous administration of L-alanine resulted in a significant increase of serum urea and a transient increase of blood ammonia concentrations. These results strongly suggest that the patient has a labile CPS protein with no activity in vitro but some activity in vivo. We consider that valproic acid may have disrupted some metabolic adaptation by reducing N-acetylglutamate in the liver, which in combination with CPS deficiency induced severe hyperammonaemia.