Synchrotron-radiation study of Fe 3d states in Cd1-xFexSe (0 <= x <= 0.4).
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Journal Article↗
Biomedical subjects
T Ohta
Publications and source records attributed to T Ohta.
Cortical alveolus breakdown in the eggs of the freshwater teleost Rhodeus ocellatus ocellatus.
Cortical alveoli and their breakdown in the eggs of the rose bitterling were morphologically investigated. Cortical alveoli of various sizes existed in multiple layers within the cortical cytoplasm of each egg. Two types of cortical alveoli were recognized--one possessed homogeneous contents; the other possessed heterogeneous contents with electron-less dense spots. The eggs were activated by a penetrating spermatozoon or by immersion in fresh water. The immersion of the eggs into fresh water induced a wave of cortical alveolus breakdown (CABD), which was propagated from the vegetal pole to the animal pole. When eggs were inseminated in fresh water, CABD progressed from both the vegetal and the animal poles of the egg, and was complete within about 20 min. The contents of the cortical alveoli were released into the perivitelline space through a large opening formed by the fusion of the plasma and cortical alveolar membranes. For a short time after CABD, the smooth inner surfaces of the cortical alveoli were readily discernible from the rougher original plasma membrane. About 30 min after immersion in fresh water, the inner surfaces of the cortical alveoli were indistinguishable from the original egg surfaces. Aequorin-injected eggs became luminescent immediately after their immersion in fresh water. The luminescence reached a maximum level about 15 min later and subsided after roughly 30 min. The result shows that increase in intracellular free Ca ions occurs during CABD.
Aequorin↗
Antimutagenic effect of umuD mutant plasmids: isolation and characterization of umuD mutants reduced in their ability to promote UV mutagenesis in Escherichia coli.
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Amino Acid Sequence↗
Clinical experience of biliary tract carcinoma associated with anomalous union of the pancreaticobiliary ductal system.
Between 1978 and 1988, 15 patients with gallbladder cancer and 2 patients with bile duct cancer were seen among 49 patients with anomalous union of the pancreaticobiliary ductal system. Radiographic findings revealed two types of this anomalous condition: one in which the pancreatic duct entered the common bile duct (type 1) and one in which the common bile duct entered the pancreatic duct (type 2). In gallbladder cancer, the common bile duct presented no dilatation, or in some patients, mild dilatation, and type-1 anomalous union was frequently found among these patients. In contrast, the two patients with bile duct cancer had cystic dilatation of the common bile duct and type-2 anomalous union. The bile amylase level, which was determined in seven patients, was extremely high in all the patients. Histopathologically, the tumors in most patients showed papillary to papillo-tubular proliferation in the mucosal layer while atypical epithelial hyperplasia was noted in the vicinity of the tumor area. These findings suggest that this congenital anomaly in both ducts results in a loss of the normal sphincteric mechanism of the duodenal papilla, and that chronic relapsing cholecystitis or cholangitis, caused by the reflux of pancreatic juice into the biliary tract, can induced progressive changes to atypical epithelial hyperplasia which may develop into carcinoma.
Adult↗
The effect of UFTM therapy on primary and metastatic colon cancer from the same human xenotransplanted into nude mice.
Successful simultaneous transplants of a cancer of the ascending colon from a 60 year old woman, taken from 3 sites: the primary focus, a lymph node metastasis, and a hepatic metastasis, into nude mice yielded KHC (-P, -N, -H) strains. These three strains were compared under uniform conditions of nude mouse transplantation from the standpoints of morphological variation, growth rate, and sensitivity to chemotherapy. The results showed no major differences in morphology or growth rate. However, an effect on chemotherapeutic sensitivity was observed in KHC-P and KHC-N, with reduction rates of 25.8 per cent and 31.4 per cent, respectively, in the MMC only treatment group with large doses, and in KHC-N and KHC-H, with reduction rates of 46.5 per cent and 34.9 per cent, respectively, in the UFTM group. Chemotherapy sensitivity not only exhibited heterogeneity by site, but also differed according to the chemotherapeutic agent used. These results indicate that this method of nude mouse transplantation is a good experimental system for comparing primary foci and metastases under uniform conditions, and also strongly suggest the presence of heterogeneity in sensitivity to chemotherapy.
Adenocarcinoma, Mucinous↗
A clinicopathological study on intrahepatic cholesterol gallstones.
In order to clarify the pathogenesis and process of the formation of intrahepatic cholesterol gallstones, we examined the clinical features, cholangiograms and pathological findings of eight patients with intrahepatic cholesterol gallstones. When examining the clinical features, one patient was found to have developed intrahepatic cholesterol gallstones 3 years after a complete lithotomy. The cholangiograms of two patients revealed small gallstones in the peripheral bile ducts of the lateral segment of the liver, and these bile ducts showed localized cystic dilatation and were tightly filled with gallstones. Conversely, their other bile ducts which contained no gallstones showed an entirely normal cholangiogram. Pathologically, these two cases showed mild chronic cholangitis, and cholesterol crystals in the peripheral bile ducts. The other six cases showed moderate or severe dilatation of the bile duct and severe chronic proliferative cholangitis. From the above results, we proposed the following theory to explain the pathogenesis and process of the formation of intrahepatic cholesterol stones: The cholesterol crystals in the peripheral intrahepatic bile ducts may be a primitive form of intrahepatic cholesterol gallstones, and the formation of intrahepatic cholesterol gallstones may precede and cause such deformities of the bile ducts as strictures or dilatations.
Adult↗
Suppressing effect of antimutagenic flavorings on chromosome aberrations induced by UV-light or X-rays in cultured Chinese hamster cells.
Chromosome aberrations induced by UV-light or X-rays were suppressed by the post-treatment with antimutagenic flavorings, such as anisaldehyde, cinnamaldehyde, coumarin, and vanillin. UV- or X-ray-irradiated surviving cells increased in the presence of each flavoring. X-ray-induced breakage-type and exchange-type chromosome aberrations were suppressed by the vanillin treatment in the G1 phase of the cell cycle and a greater decrease in the number of X-ray-induced chromosome aberrations during G1 holding was observed in the presence of vanillin. Furthermore, a greater decrease in the number of X-ray-induced DNA single-strand breaks was observed in the presence of vanillin. Treatment with vanillin in the G2 phase suppressed UV- and X-ray-induced breakage-type but not exchange-type chromosome aberrations. The suppression of breakage-type aberrations was assumed to be due to a modification of the capability of the post-replicational repair of DNA double-strand breaks. These G1- and G2-dependent anticlastogenic effects were not observed in the presence of 2',3'-dideoxythymidine, an inhibitor of DNA polymerase beta. Based on these results, the anticlastogenic effect of vanillin was considered to be due to the promotion of the DNA rejoining process in which DNA polymerase beta acts.
Animals↗
How gene families evolve.
Theories and facts of gene family evolution are reviewed. Concerted evolution is commonly observed for gene families which originated a long time ago, however there are many different types of multigene families, from uniform to diverse. The rate of homogenization by unequal crossing-over, gene conversion, etc. has been evolutionarily adjusted for each gene family. When new functions are needed by organisms, gene families may evolve into superfamilies, in which no further concerted evolution takes place, and each member of the family may acquire an indispensable function. The homeobox-containing gene family is a most exciting example of such superfamily.
Animals↗
Suppression of 6-TG-resistant mutations in V79 cells and recessive spot formations in mice by vanillin.
The antimutagenic effects of vanillin, anisaldehyde, cinnamaldehyde and coumarin were investigated in cultured Chinese hamster V79 cells in vitro. The frequencies of 6-TG-resistant mutations induced by UV or X-rays were decreased by treatment with each compound during the expression time. These decreases were not due to cytotoxic effects on cellular growth or killing effects on damaged cells. The antimutagenic effect of vanillin was also investigated in vivo in the mouse spot test using male PW and female C57BL/10 mice. Female mice were injected intraperitoneally with ethylnitrosourea (ENU) on the 10th day of pregnancy and received 3 successive oral administrations of vanillin. Administration of vanillin decreased the ENU-induced frequency of recessive carrier pups. These results indicate that vanillin acts as an antimutagen in mammalian cells both in vitro and in vivo.
Acrolein↗
In vivo anticlastogenic and antimutagenic effects of tannic acid in mice.
The anticlastogenic effect of tannic acid was studied in vivo in the mouse micronucleus test. The frequencies of micronuclei induced by mitomycin C, ethyl nitrosourea (ENU) or 4-nitroquinoline 1-oxide in mouse bone marrow cells were decreased by the oral administration of tannic acid 6 h before the mutagen injection. The observed suppressing effect was not a reflection of a delay in the formation of micronuclei by the cytotoxic effect of tannic acid. The antimutagenic effect of tannic acid was also investigated in vivo in the mouse spot test using male PW and female C57BL/10 mice. Tannic acid was given orally to pregnant females 6 h before the intraperitoneal injection of ENU on the 10th day of pregnancy. The frequency of pups with recessive color spots induced by ENU was decreased by the administration of tannic acid. The observed decrease was not due to toxic effects on the embryo. These results indicate that tannic acid acts as an anticlastogen and antimutagen in vivo.
4-Nitroquinoline-1-oxide↗
Inhibition of induction of adaptive response by o-vanillin in Escherichia coli B.
Mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were strongly enhanced in the presence of o-vanillin in E. coli B. The enhancement was also observed in uvrA, umuC, recA, polA, or alkB mutants. This effect was lower in an alkA mutant, but was restored in an alkA umuC double mutant. By contrast, the enhancing effect was almost blocked in an ada and ada umuC double mutant. It was necessary to add simultaneously MNNG and o-vanillin to the growth medium. Further investigations were conducted on the induction of ada and umuC genes using ada'-lacZ' and umuC'-lacZ' plasmids. o-Vanillin suppressed the induction of the ada gene by MNNG treatment, but not that of the umuC gene. In fact expression of the umuC gene was induced by lower concentrations of MNNG in the presence of o-vanillin. The results suggest that o-vanillin inhibits induction of the adaptive response, and consequently, the MNNG-induced mutation frequency is increased due to unrepaired O6-methylguanine.
Benzaldehydes↗
Suppressing effects of vanillin, cinnamaldehyde, and anisaldehyde on chromosome aberrations induced by X-rays in mice.
X-ray-induced chromosome aberrations were suppressed when vanillin, cinnamaldehyde, or p-anisaldehyde was given orally to mice after X-ray irradiation. Chromosome aberrations were monitored by the occurrence of polychromatic erythrocytes with micronuclei in bone marrow cells. The frequency of micronuclei was depressed about 55-60% without toxicity of the test compounds to the bone marrow.
Acrolein↗
Seasonal variations in the content of catecholamines in carp heart (Cyprinus carpio).
1. Seasonal changes in epinephrine and norepinephrine contents were demonstrated in ventricular muscle tissues of carp heart. 2. Patterns of changes in epinephrine and norepinephrine contents were similar; high during late spring-to-summer and low in winter; however, the fluctuation in epinephrine content was greater than that of norepinephrine. 3. Tyramine caused a positive inotropic effect in isolated electrically-stimulated ventricular muscles of carp heart. The inotropic effect was totally blocked by reserpine, reduced by propranolol, but not altered by atenolol. 4. These results suggest that the catecholamines released from sympathetic nerve terminals may contribute to the regulation of the seasonal change in the function of cardiac muscles in the carp.
Animals↗
Disruption of externally supported knitted dacron graft three years after implantation--a case report.
A knitted Dacron velour externally supported prosthesis was broken in two pieces at the supported portion 3 years after femoroposterior tibial bypass grafting. This type of graft problem has never been reported. Details of the clinical course, angiogram, CT scan, and scanning electron micrograph of a portion of the graft are shown. The externally supported Dacron prosthesis broke into two pieces along the broken coil of the middle portion. A possible cause of this failure may have been due to damage of the Dacron fibers in the process of heat fusing the coil. This presentation emphasizes the possibility of this rare externally supported graft complication, and the necessity for careful follow-up not only of the graft patency but also for the mechanical defects of the implanted externally supported Dacron graft itself.
Aged↗
Purification of a DNA supercoiling factor from the posterior silk gland of Bombyx mori.
A protein factor with an estimated molecular mass of 50 kDa has been purified to homogeneity from the silk gland of Bombyx mori. In the presence of a molar excess of this factor and eukaryotic DNA topoisomerase II, relaxed circular DNA is converted to the negatively supercoiled form. Eukaryotic DNA topoisomerase I cannot substitute for eukaryotic DNA topoisomerase II in the supercoiling reaction. The reaction is dependent on ATP and is inhibited by VP-16, a specific inhibitor of eukaryotic DNA topoisomerase II. When DNA topoisomerase I is subsequently added to the supercoiling reaction mixture, the supercoiled DNA becomes relaxed. These results suggest that when both the 50-kDa protein and eukaryotic DNA topoisomerase II are present in excess, unconstrained negative supercoils are introduced into DNA.
Animals↗
Dominant negative umuD mutations decreasing RecA-mediated cleavage suggest roles for intact UmuD in modulation of SOS mutagenesis.
The products of the SOS-regulated umuDC operon are required for most UV and chemical mutagenesis in Escherichia coli. The UmuD protein shares homology with a family of proteins that includes LexA and several bacteriophage repressors. UmuD is posttranslationally activated for its role in mutagenesis by a RecA-mediated proteolytic cleavage that yields UmuD'. A set of missense mutants of umuD was isolated and shown to encode mutant UmuD proteins that are deficient in RecA-mediated cleavage in vivo. Most of these mutations are dominant to umuD+ with respect to UV mutagenesis yet do not interfere with SOS induction. Although both UmuD and UmuD' form homodimers, we provide evidence that they preferentially form heterodimers. The relationship of UmuD to LexA, lambda repressor, and other members of the family of proteins is discussed and possible roles of intact UmuD in modulating SOS mutagenesis are discussed.
Amino Acid Sequence↗
Theoretical study of near neutrality. I. Heterozygosity and rate of mutant substitution.
In order to clarify the nature of "near neutrality" in molecular evolution and polymorphism, extensive simulation studies were performed. Selection coefficients of new mutations are assumed to be small so that both random genetic drift and selection contribute to determining the behavior of mutants. The model also incorporates normally distributed spatial fluctuation of selection coefficients. If the system starts from "average neutrality," it will move to a better adapted state, and most new mutations will become "slightly deleterious." Monte Carlo simulations have indicated that such adaptation is attained, but that the rate of such "progress" is very low for weak selection. In general, the larger the population size, the more effective the selection becomes. Also, as selection becomes weaker, the behavior of the mutants approaches that of completely neutral genes. Thus, the weaker the selection, the smaller is the effect of population size on mutant dynamics. Increase of heterozygosity with population size is very pronounced for subdivided populations. The significance of these results is discussed in relation to various observed facts on molecular evolution and polymorphism, such as generation-time dependency and overdispersion of the molecular clock, or contrasting patterns of DNA and protein polymorphism among some closely related species.
Biological Evolution↗
Nucleotide sequence and characteristics of the gene for L-lactate dehydrogenase of Thermus aquaticus YT-1 and the deduced amino acid sequence of the enzyme.
The gene for L-lactate dehydrogenase (LDH) from Thermus aquaticus YT-1 was cloned in Escherichia coli, using the Thermus caldophilus LDH gene as a hybridization probe, and its complete nucleotide sequence was determined. The LDH gene comprised 930 base pairs, starting with a GTG initiation codon. Its sequence had high homology (85.8% identity) with the LDH gene of T. caldophilus. The G + C content of the T. aquaticus gene was 70.9%, higher than that of the chromosomal DNA (67.4%). In particular, that in the third position of the codons used was 91.0%, similar to the T. caldophilus gene. The primary structure of T. aquaticus LDH was deduced from the nucleotide sequence of the LDH gene. It comprises 310 amino acid residues, as does T. caldophilus LDH, and its molecular mass was calculated to be 33,210 daltons. The amino acid sequence of the T. aquaticus LDH had 87.1% identity with that of the T. caldophilus LDH. At 23 positions, the respective residues differed in charge and polarity. These differences must be related to the differences in kinetic properties between the two enzymes. The constructed plasmid overproduced the T. aquaticus LDH in E. coli.
Amino Acid Sequence↗