Biomedical subjects

A Ohta

Publications and source records attributed to A Ohta.

At least 19 recordsLinked to original sources

PubMed1996

[Neutron activation analysis of biological samples].

Multi-element analysis by neutron activation analysis (NAA) in respect to medical applications is discussed. Examples of trace element determinations in pathological human liver tissues, human serum, and rat liver are given. A very sensitive method for determining fluorinated drug in very small samples of human serum by neutron activation is also described. Each biological samples (ca. 100-200 mg, lyophilized matter) was irradiated for short time (10 s or 5 min.) and for long time (24 hrs) in Rikkyo University Research Reactor or Musashi Institute of Technology Research Reactor. Concentration of 12 elements (127I, 55Mn, 26Mn, 65Cu, 23Na, 41K, 37Cl, 27Al, 48Ca, 36S, 58Fe, 64Zn) in human pathological liver, Futraful (19F) (anti-cancer fluorinated drug) clearance of human serum, and calcium uptake (48Ca) in liver of rats were determined by NAA.

Animals↗

PubMed1995

Cloning and characterization of the POX2 gene in Candida maltosa.

To study the function of acyl-CoA oxidase in an n-alkane-assimilating yeast, Candida maltosa, we isolated the POX2 gene which is a member of the acyl-CoA oxidase gene family. POX2 had a 2172-bp open reading frame (ORF) encoding an approx. 84-kDa polypeptide (724 amino acids (aa)) and was contiguous to POX4, another member of the acyl-CoA oxidase gene family on the same chromosomal DNA in a convergent arrangement. Northern blot analysis revealed that the expression of POX2 was induced in cells grown on oleic acid, n-tetradecanol and n-tetradecane. By using a gene-disruption technique, we constructed strains (termed P2DD and P4DD) in which both alleles of POX2 and POX4 were disrupted. The P2DD strain was normal in assimilation of various hydrophobic carbon sources, such as n-tetradecane, n-tetradecanol and oleic acid. In contrast, the P4DD strain was defective in its ability to grow on such hydrophobic carbon sources.

Acyl-CoA Oxidase↗

PubMed1995

Identification of a centromeric activity in the autonomously replicating TRA region allows improvement of the host-vector system for Candida maltosa.

A centromeric activity was identified in the previously isolated 3.8 kb DNA fragment that carries an autonomously replicating sequence (ARS) from the yeast Candida maltosa. Plasmids bearing duplicated copies of the centromeric DNA (dicentric plasmids) were physically unstable and structural rearrangements of the dicentric plasmids occurred frequently in the transformed cells. The centromeric DNA activity was dissociated from the ARS, which is 0.2 kb in size, and was delimited to a fragment at least 325 bp in length. The centromeric DNA region included the consensus sequences of CDEI (centromeric DNA element I) and an AT-rich CDEII-like region of Saccharomyces cerevisiae but had no homology to the functionally critical CDEIII consensus. A plasmid bearing the whole 3.8 kb fragment was present in 1-2 copies per cell and was maintained stably even under non-selective culture conditions, while a plasmid having only the 0.2 kb ARS was unstable and accumulated to high copy numbers. The high-copy-number plasmid allowed us to overexpress a gene to a high level, which had never been attained before, under the control of both constitutive and inducible promoters in C. maltosa.

Base Sequence↗

PubMed1995

Developmental expression pattern of the Caenorhabditis elegans homologue of the Drosophila suppressor of forked gene.

We cloned and sequenced the cDNA which encodes the Caenorhabditis elegans homologue (suf-1) of the Drosophila suppressor of forked (su(f)) gene product. The amino acid sequence deduced from the suf-1 cDNA shares extensive similarity with the su(f) and the human 77K subunit of the CstF, including the proline residues near the carboxy-terminus. Developmental Northern blot analysis showed that a 2.6-kb suf-1 transcript was expressed constitutively from L1 to young adult stages, suggesting it has a housekeeping function in vivo. Furthermore, this idea is consistent with the recent proposition that su(f) homologues play an essential role as a subunit of the cleavage stimulation factor (CstF) during polyadenylation of mRNA precursors.

Amino Acid Sequence↗

PubMed1995

Proliferation of intracellular membrane structures upon homologous overproduction of cytochrome P-450 in Candida maltosa.

In an alkane-assimilating yeast, Candida maltosa, a cultivation on alkane causes both induction of endoplasmic reticulum (ER)-resident membrane proteins, such as cytochrome P-450, and proliferation of ER. In this study, individual genes for alkane-inducible forms of cytochrome P-450 (P-450alk) were homologously overexpressed in C. maltosa using a galactose-inducible expression system developed in this yeast. Immunoelectron microscopy revealed that, upon the overexpression, a dramatic proliferation of ER occurred, in which overproduced P-450alk protein accumulated. The proliferated membranes were mainly tubular forms and stacks of paired membranes were also observed after prolonged expression. The tubular forms were morphologically very similar to the proliferated ER in alkane-induced C. maltosa cells. The observed proliferation of ER membranes by homologous overproduction of P-450alk, here depicted, will provide a unique opportunity for investigating the mechanisms by which cells regulate ER biogenesis, in comparison with the intrinsic form of ER proliferation.

Candida↗

PubMed1995

Dietary alpha-linolenate/linoleate balance influences learning and memory in the senescence-accelerated mouse (SAM).

The senescence-accelerated mouse (SAMP8) is a model of age-related deterioration of memory and learning ability. A semipurified diet supplemented either with safflower oil (rich in linoleate) or with perilla oil (rich in alpha-linolenate) was fed to SAMP8 mouse dams and their pups. The offspring (males from several mothers) at 28 weeks of age were used for behavioral tests. The proportions of n-3 and n-6 highly unsaturated fatty acids in brain phospholipids reflected the n-3/n-6 balance of the diets. The learning and memory abilities of the two dietary groups were tested with the Sidman active avoidance task and the light and dark discrimination learning test. The group given perilla oil showed much greater improvement in learning in the Sidman active avoidance task than did the group fed safflower oil. In the light and dark discrimination learning test, the total number of responses to positive and negative stimuli was lower in those fed perilla oil, and their responses to positive stimuli were higher than to negative stimuli after the 10th session. Consequently, the correct response ratios of discrimination were higher in the perilla oil group than in the safflower oil group. In the open field test, the total amount of locomotor activity during 5 min was lower in the perilla oil group at 7 months of age than in the group fed safflower oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1995

Analysis of the 3-phosphoglycerate kinase 2 promoter in Rhizopus niveus.

Promoter analysis was performed on the Rhizopus niveus 3-phosphoglycerate kinase 2-encoding gene (pgk2), one of the two pgk genes (pgk1 and pgk2) from this filamentous fungus sequenced so far. Deletion mutants of the promoter region were fused to the Escherichia coli uidA gene (which codes for beta-glucuronidase; GUS), and introduced into R. niveus to measure the intracellular GUS activities of the transformants. Deletion of the sequence between nt -174 to -133 (numbers indicate the position from the putative translation start codon) caused a significant decrease in the ratio of the GUS activity of the transformant cultured in glucose medium compared to that in glycerol medium. In this region, a 21-nt sequence which is well conserved between pgk1 and pgk2 is present. When it was inserted into the promoter region of the uninducible gene encoding RNase Rh of R. niveus, ligated in front of uidA and introduced into R. niveus, the GUS activity of the transformant was greatly induced by glucose, but less by glycerol. We therefore suggest that the 21-nt sequence is a glucose-inducible transcriptional activator of R. niveus. This is the first report on a transcriptional activator in zygomycetes.

Base Sequence↗

PubMed1995

In vivo evidence for non-universal usage of the codon CUG in Candida maltosa.

An alkane-assimilating yeast Candida maltosa had been studied in order to establish systems suitable for biotransformation of hydrophobic compounds. However, functional expression of heterologous genes tested for this purpose had not been successful in several cases. On the other hand, it had been reported that the codon CUG, a universal leucine codon, is read as serine in C. cylindracea. The same altered codon usage had also been suggested by in vitro experiments in some Candida yeasts which are phylogenetically closely related to C. maltosa. In this study we have shown that the failure in functional expression of a heterologous gene is due to the fact that the codon CUG is read as serine in C. maltosa. This conclusion was drawn from the following experimental results: (1) when a cytochrome P450 gene of C. maltosa containing a CTG codon was expressed in C. maltosa, the corresponding amino acid was found to be serine, and not leucine; (2) a tRNA gene with an almost identical structure to that of the tRNASerCAG gene of C. albicans could be isolated from the genome of C. maltosa; (3) the Saccharomyces cerevisiae URA3 gene, which has one CTG codon, could not complement the ura3 mutation of C. maltosa as itself, but when the CTG codon was changed to another leucine codon, CTC, the mutated gene could complement the ura3 mutation. The last result is the first example of succeeding in functional expression of a heterologous gene in Candida species having an altered codon usage by changing the CTG codon in the gene to another codon.

Amino Acid Sequence↗

PubMed1995

Cloning of the Rhizopus niveus pyr4 gene and its use for the transformation of Rhizopus delemar.

We have cloned a pyr4 gene encoding orotidine-5'-monophosphate decarboxylase of the filamentous fungus Rhizopus niveus. The pyr4 gene of R. nivens has an open reading frame composed of 265 amino-acid residues and has two putative introns. We have also isolated a pyr4 mutant of Rhizopus delemar from 5-fluoroorotic acid-resistant mutants and transformed it with the pyr4 gene of R. niveus as a selectable marker. Introduced DNA was integrated into the chromosome in a multiple tandem array. The mitotic stability of the introduced DNA was increased by a repeated sporulation process. The expression of the Escherichia coli beta-glucuronidase gene in R. delemar was successfully obtained under the control of the pgk2 gene promoter of R. niveus by co-transformation with the pyr4 gene.

Amino Acid Sequence↗

PubMed1995

Risk factors for the development of acute disseminated intravascular coagulation in patients with systemic lupus erythematosus.

Since acute disseminated intravascular coagulation (DIC) often contributes to a fatal outcome in patients with systemic lupus erythematosus (SLE), prediction of its development is important to prevent the occurrence of such an event. To analyze the risk factor(s) contributing to the development of acute DIC in SLE, we carried out a retrospective study of a series of 129 SLE patients, eight of whom developed DIC during the course of this disease, to assess which of the easily assessable parameters, present at the time of first medical examination, were of predictive significance. The important individual variables, determined by univariate analysis, were male sex, leukopenia, and infection. These factors were placed in a multivariate logistic regression model, and only one factor, infection at first medical examination, was found to have predictive significance for the development of acute DIC in SLE patients. The prevention and control of infection in SLE patients might have implications for preventing the development of acute DIC.

Acute Disease↗

PubMed1995

CYP52 (cytochrome P450alk) multigene family in Candida maltosa: identification and characterization of eight members.

Previously, we characterized three genes and presented evidence for an n-alkane-inducible cytochrome P450 (P450alk) multigene family in an n-alkane-assimilating and diploid-type yeast, Candida maltosa. In the present report, we isolated and characterized additional members of this gene family, including a total of thirteen P450alk-related sequences (eight genes and five of their alleles). Two sets, each consisting of two genes, were tandemly arranged in the genome. A gene replacement experiment showed that at least one gene had only a single allele in the genome. The determined nucleotide and the deduced amino acid sequences indicated that all had a characteristic constituent for P450s and exhibited amino acid identities from 94% to 37% to each other. Six genes showed relatively higher similarities to each other than to the other two genes and were thus classified into a subfamily. All the members of this subfamily were assigned to the same single chromosome, showing a good correlation between sequence similarity and chromosomal linkage. Although all the genes except for one were induced by n-alkane, their inducibilities by some other aliphatic carbon sources showed variabilities.

Alleles↗

PubMed1995

Calcium and magnesium absorption from the colon and rectum are increased in rats fed fructooligosaccharides.

We investigated the effects of fructooligosaccharides on the absorption of calcium, magnesium and water from the colon and rectum of rats fed a control diet or the control diet containing 50 g fructooligosaccharides/kg. Chromium-mordanted cellulose was used as an unabsorbable marker to calculate apparent absorption of calcium and magnesium. There was a positive correlation (r = 0.982, P < 0.001 in rats fed the control diet and r = 0.975, P < 0.001 in rats fed the fructooligosaccharides-containing diet) between the amount of chromium and the dry weight of each fecal pellet in the colon and rectum. Ratios of calcium to chromium and magnesium to chromium in fecal pellets in the colon and rectum were calibrated from the Ca:Cr and Mg:Cr ratios of cecal contents. In rats fed the fructooligosaccharides-containing diet, but not in rats fed the control diet, these ratios were correlated with the fractional length of transit along the colon and rectum, indicating linear disappearance of calcium and magnesium during the colorectal passage. Total apparent absorption of calcium and magnesium, predicted from regression equations with the Ca:Cr and Mg:Cr ratios of cecal contents, agreed well with those calculated from the Ca:Cr and Mg:Cr ratios of feces. The consumption of fructooligosaccharides did not affect net water absorption from the colon and rectum. These results indicated that fructooligosaccharides significantly increased calcium and magnesium absorption and that indigestible and fermentable carbohydrate facilitates colorectal absorption of calcium and magnesium.

Animals↗

PubMed1995

Determination of various cytokines and type III procollagen aminopeptide levels in bronchoalveolar lavage fluid of the patients with pulmonary fibrosis: inverse correlation between type III procollagen aminopeptide and interferon-gamma in progressive patients.

We measured levels of cytokines and type III procollagen aminopeptides (procollagen III peptides) in bronchoalveolar lavage fluid obtained from 20 patients with stable pulmonary fibrosis (PF) and seven patients with progressive PF, and nine control subjects to determine the role of cytokines in the development of PF. Procollagen III peptide levels were markedly increased in progressive PF patients. Tumour necrosis factor-alpha, interleukin-6, transforming growth factor-beta and interferon-gamma (IFN-gamma) levels were elevated in both PF patients as compared with controls, with a tendency of higher levels in progressive patients, whereas interleukin-1 beta (IL-1 beta) level was decreased in both PF patients. When the correlation between procollagen III peptide and various cytokine levels was analysed the only significant correlation was inversely between procollagen III peptide and IFN-gamma in progressive PF patients. These results indicated that although multiple cytokines may be involved in the development of PF, the negative role of IFN-gamma in active collagen synthesis could be also important.

Adult↗

PubMed1995

Possible inhibitory effect of lithium on peripheral conversion of thyroxine to triiodothyronine: a prospective study.

The effect of lithium on thyroid function was studied in 18 neuroleptic-treated male chronic schizophrenic in-patients. Lithium carbonate was administered for 8 weeks at a dosage giving a mean serum level of 0.79 mmol/l. Blood was obtained just before and after 8 weeks of lithium administration to determine the serum free thyroxine (free T4) levels, free triiodothyronine (free T3) levels and thyrotropin (TSH) levels. Overall, free T4 and TSH levels significantly increased whereas free T3 levels did not change. Two (11%) patients had abnormally increased free T4 levels and abnormally decreased free T3 levels after 8 weeks of lithium administration. These findings suggest that lithium may inhibit the peripheral conversion of free T4 to free T3 in some susceptible patients.

Adult↗

PubMed1995

Neurofibromatosis 2 and neurilemmomatosis gene are identical.

Neurofibromatosis 2 (NF2) is an autosomal dominant disorder characterized by the occurrence of bilateral acoustic neuromas, as well as meningiomas and schwannomas. The gene locus for NF2 resides on chromosome 22q12 and has been cloned recently. Neurilemmomatosis is characterized by multiple cutaneous and spinal neurilemmomas without other signs of NF1 or NF2. Many cases with this disorder include the diagnosis of neurofibromatosis or other rare diseases unexplained by current nosology. In this study, we analyzed the peripheral leukocytes and tissue from cutaneous neurilemmomas of seven patients with neurilemmomatosis using DNA markers for different regions of chromosome 22. We detected allelic losses in three of seven tumors from seven patients with a probe for the NF2 region of the long arm of chromosome 22 and the germ-line mutations in two of three tumors from the same three patients. Mutations in the NF2 gene were a deletion from at least codon 334 to 579 and G insertion at codon 42. We conclude that the neurilemmomatosis locus lies within the NF2 region and that these diseases might be identical.

Adult↗

PubMed1995

Basal cell carcinoma with eccrine differentiation.

We describe a light, electron microscopic, and immunohistochemical study of basal cell carcinoma with eccrine differentiation. The cytoplasm did not stain with fat stain on cryostat sections, but contained numerous gland-like structures. Immunohistochemistry on formalin fixed, paraffin embedded tissues using antibodies to human involucrin, thirteen kinds of cytokeratin, S-100 protein, and carcinoembryonic antigen (CEA) was performed. We found that tumor cells were positive for keratin, PKK1, MA-903, No 8, No 19, AE 1, AE 3, and 5 + 8. Tumor cells were negative for S-100 protein, CEA, and the other antigens examined. Electron microscopy demonstrated short microvilli and amorphous materials within the intracytoplasmic cavity. We concluded that this tumor is basal cell carcinoma with eccrine differentiation.

Basal Cell Carcinoma↗

PubMed1995

Lithium addition to neuroleptic treatment in chronic schizophrenia: a randomized, double-blind, placebo-controlled, cross-over study.

We studied the effect of lithium addition to neuroleptic treatment in chronic schizophrenia, for which contradictory results have been produced in previous studies. Twenty-one chronic schizophrenic inpatients received lithium in a study with randomized, double-blind, placebo-controlled, cross-over design consisting of 8 weeks each of treatment with lithium capsules and identical placebo capsules. The total Brief Psychiatric Rating Scale (BPRS) scores at week 8 of the lithium treatment were improved significantly compared with those at week 8 of the placebo treatment. Of the BPRS subscales, however, only anxiety-depression improved, whereas none of the subscales for anergia, thought disturbance, activation and hostile-suspiciousness improved. There was no significant difference between the total Scale for the Assessment of Negative Symptoms (SANS) scores at any time during lithium and placebo treatment. These results suggest that the addition of lithium to neuroleptic treatment improves anxiety-depression in chronic schizophrenia.

Adult↗

PubMed1995

Inducible expression of a gene encoding an L41 ribosomal protein responsible for the cycloheximide-resistant phenotype in the yeast Candida maltosa.

In a previous paper (S. Kawai, S. Murao, M. Mochizuki, I. Shibuya, K. Yano, and M. Takagi, J. Bacteriol. 174:254-262, 1992), we showed that in each genome of several yeast species, there is one of two types of L41 gene, one for an L41 (Q-type) protein which confers cycloheximide (CYH) resistance or one for an L41 (P-type) protein which does not. These genes have been suggested to be responsible for the CYH response used in taxonomy. For example, Saccharomyces cerevisiae, which is CYH sensitive, has a P-type L41 gene, while Kluyveromyces fragilis and Candida maltosa, which are CYH resistant, have Q-type L41 genes. However, in contrast to K. fragilis, which is constitutively resistant to CYH, C. maltosa is inducibly resistant to CYH. Here, we show that C. maltosa has both types of the L41 gene in its genome and that expression of the Q-type L41 gene is induced by CYH while the P-type L41 gene is constitutively expressed.

Base Sequence↗