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Biomedical subjects

J M Song

Publications and source records attributed to J M Song.

34 records · Page 2Linked to original sources
PubMed1995

Nucleotide sequence and characterization of the Saccharomyces cerevisiae RPL19A gene encoding a homolog of the mammalian ribosomal protein L19.

A gene designated RPL19A has been identified in the region downstream from the 3'-end of the Saccharomyces cerevisiae MIS1 gene encoding the mitochondrial C1-tetrahydrofolate synthase. The gene codes for the yeast ribosomal protein YL19 which exhibits 57.5% identify with the mammalian ribosomal protein L19. RPL19A is one of two functional copies of the YL19 gene located on chromosome II. The disruption of RPL19A has no effect on the growth of the yeast. The RPL19A gene contains an intron located near the 5'-end. The 5'-flanking region contains one similar and one complete UASrpg upstream activating sequence. RPL19A was also found to be adjacent to the chromosome II AAC3 gene, encoding the mitochondrial ADP/ATP carrier protein.

Amino Acid Sequence↗
PubMed1993

Single-stranded DNA binding activity of C1-tetrahydrofolate synthase enzymes.

In eukaryotes C1-5,6,7,8-tetrahydrofolate (THF) synthase is a trifunctional enzyme that catalyzes the interconversion of reduced forms of folate to supply activated one-carbon units required for a variety of metabolic pathways. The enzymatic activities include 10-formyl-THF synthetase (EC 6.3.4.3), 5,10-methenyl-THF cyclohydrolase (EC 3.5.4.9), and 5,10-methylene-THF dehydrogenase (EC 1.5.1.5). In bacteria separate, monofunctional or bifunctional polypeptides catalyze the same reactions. We have purified C1-THF synthase from the fission yeast Schizosaccharomyces pombe and found its physical and enzymatic properties similar to those of other eukaryotic C1-THF synthase enzymes. Unexpectedly, the S. pombe enzyme bound strongly (Keq = 100 pM) to single-stranded DNA, but not to double-stranded DNA or to RNA. The binding was sequence-independent, apparently not cooperative, and not detectably inhibited by C1-THF synthase substrates or cofactors. Trifunctional cytoplasmic enzyme from Saccharomyces cerevisiae and monofunctional (synthetase) enzyme from Clostridium acidiurici also bound tightly to single-stranded DNA, while bifunctional (dehydrogenase and cyclohydrolase) enzyme from Escherichia coli did not, suggesting that single-stranded DNA binding is a conserved function of the synthetase domain of C1-THF synthase enzymes.

Aminohydrolases↗
PubMed1993

Function of yeast cytoplasmic C1-tetrahydrofolate synthase.

The protein product of the ADE3 gene of the yeast Saccharomyces cerevisiae has been identified as the cytoplasmic trifunctional C1-tetrahydrofolate (THF) synthase, which possesses 10-formyl-THF synthetase (EC 6.3.4.3), 5,10-methenyl-THF cyclohydrolase (EC 3.5.4.9), and 5,10-methylene-THF dehydrogenase (EC 1.5.1.5) activities. However, it has been suggested that the ADE3-encoded C1-THF synthase does not play a role in providing the enzymes involved in the generation of one-carbon intermediates in the biosynthesis of the purine bases but functions in maintaining the structural integrity of the enzyme complex involved in purine biosynthesis [Barlowe, C. K. & Appling, D. A. (1990) Mol. Cell. Biol. 10, 5679-5687]. This hypothesis is based on their finding that the presence of the full-length ADE3 C1-THF synthase, whether catalytically active or not, is correlated with the Ade+ phenotype. In contrast to their results, our deletion analysis of the ADE3 gene indicates that the presence of either the synthetase or dehydrogenase/cyclohydrolase domains of C1-THF synthase is enough to complement the adenine requirement in ade3 strains. These results are also consistent with those obtained in heterologous expression of spinach and Clostridium acidiurici monofunctional synthetases in ade3 strains. Heterologous expression studies show that the high synthetase activity may be correlated with the increased growth in medium lacking adenine. These results suggest that the catalytic activity of the C1-THF synthase is involved in purine biosynthesis.

Aminohydrolases↗
PubMed1992

The prognostic significance of DNA ploidy pattern in transitional cell cancer of the renal pelvis and ureter: continuing follow-up.

Among 190 patients operated on for transitional cell cancer of the renal pelvis and/or ureter from 1976 to 1990, 95 had their tumor studied by flow cytometry. Of these, the prognostic significance of the DNA ploidy pattern with respect to the standard pathologic features was assessed in a retrospective analysis, where survival information were updated to October 1991 and the mean follow-up of patients exceeded 5.5 years (longest follow-up: 15.5 years). Five and ten-year survival probabilities for the whole group were, respectively, 65.5 and 51%. Patients with a diploid tumor had significantly better survival rates than patients with tetraploid/aneuploid cancer (p less than 0.00001). The impact of the DNA ploidy on survival was confirmed by a multivariate analysis of prognostic factors, where only tumor grade (p less than 0.0001), tumor stage (p less than 0.0001), number of neoplastic foci (p = 0.022) and nuclear DNA pattern (p less than 0.068) had a significant influence on survival. In the group of patients with low-stage (pTa-pT1) and low-grade (G1-G2) transitional cell cancer of the upper urinary tract, the DNA analysis was unable to identify any subset of patients at higher risk for disease progression.

Carcinoma, Transitional Cell↗
PubMed1991

Transitional cell carcinoma of the upper urinary tract: evaluation of prognostic factors by histopathology and flow cytometric analysis.

Prognostic factors in transitional cell carcinoma of the upper urinary tract were assessed with histopathological examination and flow cytometric analysis in a series of 127 patients operated upon between 1976 and 1988. In particular, we evaluated the usefulness of flow cytometry to identify patients who require adjuvant treatment among those with low grade and low stage disease (51% in this series). A multivariate analysis was done on 92 cases, considering patient age and sex, stage, grade and number of lesions (unifocal versus multifocal), site (renal pelvis versus ureter), presence of vesical tumors, recurrences along the urinary tract or in the bladder, type of operation and nuclear deoxyribonucleic acid (DNA) ploidy (diploid versus tetraploid/aneuploid tumors). Only the stage (p = 0.001), grade (p = 0.001) and, to a lesser extent, the DNA pattern (p = 0.031), as well as the number of lesions (p = 0.061) were determinant for prognosis. In regard to the subgroup of 41 patients with grade 2 or less, stage P1 or less tumors, no significant difference in survival was demonstrated between diploid and nondiploid tumor patients. However, 7 of 10 patients from the latter group are still under observation. Therefore, our conclusions may have to be modified in the future.

Adult↗
PubMed1990

Effects of multiple yeast rad3 mutant alleles on UV sensitivity, mutability, and mitotic recombination.

A yeast strain was constructed that had a disruption of the chromosomal RAD3 gene and carried a series of centromeric plasmids with defined mutations in this gene. Using this isogenic collection, we examined sensitivity to UV radiation, spontaneous and UV radiation-induced mutagenesis, and mitotic recombination. Several alleles resulted in a marked increase in UV sensitivity. Most of these alleles were found to carry mutations located in consensus motifs for DNA helicases. Other alleles caused a modest or no increase in UV sensitivity and carried mutations in regions of the Rad3 polypeptide that are apparently not conserved. This correlation suggests that the DNA helicase activity of Rad3 protein is required for nucleotide excision repair of DNA. Some rad3 alleles conferred a marked increase in the frequency of spontaneous mutagenesis, including nonsuppressor reversion of the lys2-1 ochre mutation. These alleles also showed a good correlation with conserved DNA helicase domains, suggesting that the Rad3 DNA helicase also plays a role in the fidelity of DNA synthesis or postreplicative mismatch correction. Several rad3 mutator alleles also resulted in increased levels of mitotic recombination. Increased spontaneous mutagenesis and mitotic recombination are characteristic features of the Rem- phenotype. However, in contrast to the prototypic Rem- phenotype, the rad3 mutator alleles identified in this study did not confer inviability in the presence of mutations in the RAD50 or RAD52 gene required for strand break repair of DNA.

Alleles↗
PubMed1989

Mutations in ADE3 reduce the efficiency of the omnipotent suppressor sup45-2.

Mutations in a known yeast gene, ADE3, were shown to act as an antisuppressor, reducing the efficiency of the omnipotent suppressor, sup45-2. The ADE3 locus encodes the trifunctional enzyme C1-tetrahydrofolate synthase, which is required for the biosynthesis of purines, thymidylate, methionine, histidine, pantothenic acid and formylmethionyl-tRNA(fMet. The role of this enzyme in translational fidelity had not previously been suspected.

Aminohydrolases↗
PubMed1989

Hamartoma of the urachal remnant.

A case of urachal hamartoma occurred in the urinary bladder of a 45-year-old woman, whose presenting symptoms were frequent urination and nocturia. Computed tomographic and contrast radiologic examinations demonstrated a broad-based 5-cm polypoid mass at the dome of the bladder. Grossly the polypoid mass was smooth surfaced and covered by innocent transitional epithelium. The mass and the underlying bladder wall consisted of multiple cystic cavities of various sizes and hyperplastic smooth-muscle bundles. Light microscopy identified numerous tubuloglandular structures, most of them lined by transitional cell epithelium. Simple or ciliated columnar cells and occasional mucous cells were also present, particularly in the epithelium of cystic cavities. Some tubules had communicated with the bladder lumen. Hamartoma of the urachal remnant should be included in the differential diagnosis of urachal and bladder tumors.

Female↗
PubMed1987

Allosuppressors that enhance the efficiency of omnipotent suppressors in Saccharomyces cerevisiae.

Two recessive Mendelian-allosuppressors have been isolated and have been shown to enhance the efficiency of omnipotent suppressors thought to be translational ambiguity mutations. These allosuppressors are unlinked to each other or to the omnipotent suppressors on which they act. They also increase the efficiency of the serine-inserting UAA-suppressor, SUP16. One allosuppressor is allelic or tightly linked to the previously isolated sal2. Another allosuppressor, called sal6, represents a new locus, unlinked to the previously isolated sal1-sal5 that enhance the efficiency of the UAA-suppressors. When present singly in the absence of suppressors or other modifiers the sal2 and sal6 mutations do not have suppressor activity. However, when sal2 and sal6 are combined together in a haploid cell they do suppress weakly. In addition sal2 becomes a weak suppressor in the presence of the [eta +] modifying factor.

Genes, Fungal↗
PubMed1985

Interaction of UAG suppressors and omnipotent suppressors in Saccharomyces cerevisiae.

Haploids bearing the dominant UAG suppressor, SUP7-a, and various alleles of the omnipotent suppressor sup35 were examined. The presence of the UAG suppressor reduced the efficiency of some alleles of sup35, and caused other sup35 alleles to be lethal. A nonclassical interaction of the dominant suppressor tRNA and the ribosome is proposed to explain these observations.

Codon↗
PubMed1983

Effect of ozone on DNA-repair deficient mutants of Bacillus subtilis.

The wild type strains and DNA-repair deficient mutant strains of B. subtilis were exposed to ozone. The results show that the lethal effect of ozone is greatly influenced by factors such as ozone concentration, treatment time, growth phase, and treatment of medium. The recA and recC loci seem to be most important and perhaps the polA and uvrA loci may also be required, but the recB and recD loci are not required for the repair of DNA-damase induced by ozone in B. subtilis.

Bacillus subtilis↗
PubMedDate not supplied

Heart failure in Korean elderly patients - clinical features, prognosis and prognostic factors.

Heart failure (HF) is very common in the elderly but there are not sufficient data about the clinical characteristics and prognostic factors of HF among the Asian elderly patients. The aim of the study was to find out the clinical characteristics, survival, and prognostic factors of HF in Korean elderly patients. Among elderly patients admitted from February 1995 to February 1998, the patients with a discharge diagnosis of HF were enrolled. Through the medical record review, the diagnosis was confirmed and clinical parameters to affect survival were identified. Total number of the subjects was 104 [age: 77+/-7 years (65-96), male:female=36:68, follow-up duration: 20+/-14 months, LVEF: 46+/-16%]. Ischemic heart disease (IHD) was the most common cause of HF (42%) followed by valvular heart disease (28%), and hypertension (20%). The 1-year survival rate was 71.3%. Advanced age [risk ratio (RR): 1.41 per 5 years of age; 95% CI: 1.11-1.80] and reduced left ventricular ejection fraction (0.69 per 10%, 0.52-0.93), poor initial functional class (2.40, 1.15-5.00), diabetes (2.79, 1.30-5.97) and past history of HF (2.37, 1.10-5.10) badly affected the survival rates. When the Cox proportional hazard model was applied for multivariate analysis, only aging (1.64 per 5 years of age, 1.19-2.28) and diabetes (4.92, 1.83-13.23) predicted poor prognosis. Twenty-seven percent of the patients had diastolic HF (LVEF>45%, LVEDD<55 mm) who had higher survival rates with marginal significance (0.35, 0.10-1.17, P=0.09).

Journal Article↗