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Biomedical subjects

J Choe

Publications and source records attributed to J Choe.

At least 73 records · Page 4Linked to original sources
PubMed1993

The effect of the age of the recipients on pregnancy rates following donor-oocyte replacement.

PURPOSE: Besides waning ovarian function with advancing age, the question of a uterine senescence factor has been proposed as a cause of decreased fecundity. The replacement of oocytes from younger donors into older recipients allows further investigation into the aging endometrium. RESULTS: The pregnancy rate was considerably lower, 8.5% in recipients in ovarian failure who were > or = 40 years old (n = 23) compared to younger recipients, < 40 years of age (n = 55), who were also in ovarian failure, which would support the uterine senescence theory. CONCLUSION: The endometrial factor may be manifested by failure to generate a critical endometrial thickness of 10 mm by sonography in 61% of the older group, compared to only 29% of the younger group. Future studies should address methods of improving the endometrial thickness in the older group, to determine if improved pregnancy rates will occur and to evaluate whether increasing luteal support with extra progesterone may also improve pregnancy rates.

Adult↗
PubMed1993

The effect of endometrial thickness and echo pattern on in vitro fertilization outcome in donor oocyte-embryo transfer cycle.

There have been some conflicting data concerning the importance of endometrial thickness and echo patterns before transfer in different IVF-ET situations under different COH regimens. We previously found in women undergoing IVF-ET after luteal phase LA-hMG a significantly higher PR in those patients attaining at least a 10-mm endometrial thickness and a lower rate in those women with an entirely homogeneous hyperechogenic endometrium (pattern C). The present study evaluated the relationship of endometrial thickness and echo pattern to PRs in donor oocyte recipient immediately before transfer. There were 16 pregnancies in 58 cycles (27.5%). Conclusions similar to the previous COH study were reached concerning the > or = 10-mm thickness levels correlating with improved PRs (9% versus 38.7%, P < 0.01). In contrast, no correlation with echo pattern was found.

Adult↗
PubMed1993

P3 promoter element of bovine papillomavirus.

The P3 promoter activity of Bovine papillomavirus (BPV) and cis-acting DNA element of P3 promoter required for transcription were examined using chloramphenicol acetyltransferase (CAT) assay. The results show that P3 promoter is a very weak promoter compared to P2 promoter in BPV and E2 transactivator is required for the maximal transcription of P3 promoter in a BPV upstream regulatory region (URR)-dependent manner. Deletion experiments by nuclease Bal-31 were carried out to define P3 promoter element. The DNA sequences between nt 712 and nt 802 of BPV are required for efficient transcription of the P3 promoter. This 90 bp region contains SV40 enhancer core sequences and an ATF binding site.

Base Sequence↗
PubMed1992

Comparative analysis of inositol phospholipid metabolism in viral and chemical transformation of mammalian cells.

1. Inositol phospholipid metabolites were measured from virally and chemically transformed cells. 2. Increased levels of PIP and PIP2 were observed from both transformed cell lines as compared with controls. 3. Intracellular levels of IP3 were also increased approximately three folds in BPV-1 infected ID 13 cells and in 3-MC transformed NIH 3T3 cells. 4. The results suggest that phosphorylation of phosphatidylinositols and enhanced generation of IP3 second messenger molecules are the common signal transducing process leading to the cell transformation.

Animals↗
PubMed1992

An evaluation of couples with failure of fertilization in vitro.

Attempts at in-vitro fertilization (IVF) may be used as a method of evaluating whether in a given couple, the inability of the sperm to fertilize the oocyte may be the cause of infertility. We evaluated all IVF patients in our practice who had at least one cycle with no fertilization to determine how often this was an isolated event or was repeated in multiple cycles; would poor semen quality be found as a frequent cause; and how well can a donor sperm or oocyte 'probe' uncover which of the two is the problem? Of 35 couples who used their own gametes exclusively, 30 (85.7%) had at least one cycle with zero fertilization; 42.5% of those failing to fertilize in cycle 1 and 35% of those failing in cycle 2 had a subnormal concentration of motile spermatozoa, morphology or hypo-osmotic swelling test scores. The pregnancy rate per cycle with both husband's and wife's gametes was only 2.3% (3/130), but was 8.3% for those using donor spermatozoa (3/36) and 18.2% (2/11) for donor oocytes. Thus, failing to fertilize in a given cycle does not necessarily predict failure to fertilize in a subsequent cycle, but does predict a poor fertility outcome unless donor gametes are used.

Adult↗
PubMed1991

Influence of endometrial thickness and echo patterns on pregnancy rates during in vitro fertilization.

Previous data has suggested that improved PRs were seen in women with increased endometrial thickness as determined by sonography before oocyte retrieval. The hyperstimulation protocol used was CC-hMG. The study presented herein was initiated to evaluate if a similar trend was evident in women whose hyperstimulation protocol included the long LA-hMG therapy. We also demonstrated an improved PR in women with greater endometrial thickness, but in general, the endometrium was thicker in the pregnant women treated with the gonadotropin-releasing hormone agonist than in those treated with CC.

Embryo Transfer↗
PubMed1991

Inhibition of mutagenesis and transformation by root extracts of Panax ginseng in vitro.

The root extract of Panax ginseng was investigated for its inhibitory effects on DNA synthesis, mutagenicity, and cellular transformation using V79 and NIH 3T3 cells. DNA synthesis measured by the [3H]thymidine incorporation into V79 Chinese hamster lung cells was significantly decreased by the addition of ginseng extract (0-1 microgram/ml) to the medium. However, ginseng extract was found to increase the rate of DNA excision repair synthesis in V79 cells in response to treatment with UV radiation or methyl methanesulfonate. The extract also showed decreased mutation frequency when mutagenicity was examined using V79 cells at the hypoxanthine-guanine phosphoribosyl transferase locus as resistance to 6-thioguanine after exposure to methyl methanesulfonate. We also found that the components of ginseng extract continue to exert an inhibitory effect on the transformation of NIH 3T3 cells initiated by 3-methylchloanthrene, methyl methanesulfonate, and 1-methyl-3-nitro-1-nitrosoguanidine.

Animals↗
PubMed1990

The E2 transactivator of bovine papillomavirus type 1 is expressed from multiple promoters.

The E2 proteins of bovine papillomavirus type 1 (BPV-1) are a family of site-specific DNA-binding proteins which regulate viral transcription by repression and activation. Repressors E2-TR and E8/E2 are expressed from promoters P5 (P3080) and P3 (P890), respectively. Previous reports have provided evidence that the transcript for the 48-kilodalton transactivator is initiated from a promoter proximal to the open reading frame encoding this protein (P2440 or P4). Our studies extend these findings and show that the E2 transactivation gene is expressed from multiple promoters. We have described the isolation of a cDNA (N15-2) which represents an RNA species expressed from the P3 promoter. The major exon of this species was produced by splicing to an acceptor located at nucleotide 2558 and contained the complete E2 open reading frame. The acceptor is probably utilized by yet another more abundant mRNA expressed from the P2 promoter (A. Stenlund, J. Zabielski, H. Ahola, J. Moreno-Lopez, and U. Pettersson, J. Mol. Biol. 182:541-554, 1985). Linked to a surrogate promoter, the N15-2 cDNA can transactivate an E2-responsive reporter gene. BPV-1 plasmids containing mutations either in the 2558 splice acceptor or in the P4 promoter showed significantly reduced transforming ability and reduced ability to transactivate an E2-responsive reporter, while a double mutant was inactive in both assays. The transformation defect was complemented by an E2 expression vector, and the BPV genome absolutely required the E2 protein to transactivate in the second assay. Thus, these genetic experiments show that alternate modes of E2 expression contribute to the E2 mRNA pool. Direct analysis of cytoplasmic RNA from transformed cultured cells proves that transcripts containing the 2558 acceptor exon are approximately as abundant as the P4 type E2 mRNAs. Furthermore, analysis of the E2 proteins present in various cell lines harboring specific BPV-1 mutants, including the 2558 acceptor mutant, proves that alternate modes of E2 expression exist. The ability of the E2 activator and repressors to each be independently expressed from multiple E2-responsive promoters probably adds to the resiliency of the latent virus as a plasmid and may be important for its homeostasis within the cell in different environmental or developmental situations.

Animals↗
PubMed1990

Multiple system degeneration with glutamate dehydrogenase deficiency: pathology and biochemistry.

The neuropathological findings in a patient with antemortem diagnosis of olivopontocerebellar atrophy (OPCA) and reduced leucocytic glutamate dehydrogenase (GDH) activity included cerebellar cortical degeneration, most marked in the superior vermis, mild atrophy of the pons and the inferior olivary nucleus, marked reduction of anterior horn cells at all levels and gliosis in both lateral columns. GDH activities and their thermolability in "soluble" and "particulate" fractions in the cerebral cortex, cerebellar hemisphere and vermis were not significantly different from the values in two control brains. GDH mRNA in the patient's brain was not altered in size or amount.

Aged↗
PubMed1989

Bovine papillomavirus type 1 encodes two forms of a transcriptional repressor: structural and functional analysis of new viral cDNAs.

Genetic and biochemical evidence has established that the E2 open reading frame (ORF) of bovine papillomavirus type 1 encodes at least two different site-specific DNA-binding proteins, one which activates and the other which represses expression from a viral promoter (P. F. Lambert, B. A. Spalholz, and P. M. Howley, Cell 50:69-78, 1987). We have obtained data which show that a second form of the repressor gene is expressed in transformed cells harboring stable viral plasmids. The structural details of this gene have been discerned by cDNA cloning, by RNase protection, and by primer extension analysis of in vivo RNA. Moreover, data from in vitro transcription experiments support the notion that this form of the E2 repressor is expressed from a novel viral promoter and that a small exon from another ORF is linked to an active repressor domain in E2. Thus, two different forms of the repressor are expressed from different promoters and might be independently regulated either in the cell cycle or in different tissue types. We show by functional in vivo assays utilizing a cDNA vector encoding this gene that the trans-acting factor has in vivo activities similar to those of the known repressor. Our screen of a cDNA library for cDNA clones representing bovine papillomavirus transcripts has also revealed a number of other novel structures defining new donor and acceptor RNA-processing sites. Notably, clones which conceptually can be translated to yield an E7 protein, the viral M gene, and the entire E2 ORF have been characterized. Finally, truncated versions of putative E8 cDNAs were also obtained.

Bovine papillomavirus 1↗
PubMed1988

Carbon dioxide laser laparoscopy by means of a 3.0-mm diameter rigid wave guide.

Rigid carbon dioxide wave guides measuring 300 to 500 mm in length and 3.0 mm in diameter were evaluated in rabbits and humans. The wave guide provided an effective laser delivery system for operative laparoscopy. The tested guide was introduced into the abdominal cavity alternatively via the operating channel of a 9-mm operating laparoscope, through the central channel of a smoke evacuation/irrigation cannula, or via a 3.25-mm second puncture trocar. In contrast to previously tested flexible guides, the rigid device transmitted a visible helium-neon aiming beam, power up to 50 watts, and a beam diameter of less than 1 mm. The hollow guide was kept free of smoke by-products by continuous purging with carbon dioxide gas flowing at 800 to 1000 cc per minute. All wave guides could be sterilized by ethylene oxide gas or Cidex (Surgikos, Arlington, TX) soaking. Fourteen women with a variety of reproductive disorders underwent laser laparoscopy. The rigid wave guide was fired at distances ranging from less than 1 mm to 30 mm from the target and performed with maximal impact at distances of 3 to 5 mm. Perhaps the greatest advantage of this system is its ability to focus-defocus while directly coupling to the handpiece of standard lasers and requiring no special alignment procedures.

Animals↗
PubMed1988

The product of the bovine papillomavirus type 1 modulator gene (M) is a phosphoprotein.

The M gene of bovine papillomavirus type 1 has been genetically defined as encoding a trans-acting product which negatively regulates bovine papillomavirus type 1 replication and is important for establishment of stable plasmids in transformed cells. The gene for this regulatory protein has been mapped in part to the 5' portion of the largest open reading frame (E1) in the virus. We constructed a trpE-E1 fusion gene and expressed this gene in Escherichia coli. Rabbits were immunized with purified fusion protein, and antisera directed against the product were used to identify the M gene product in virus-transformed cells. In this way a polypeptide with an apparent molecular mass of 23 kilodaltons was detected. The virus-encoded product is phosphorylated and can be readily detected by immunoprecipitation assays from cells transformed by the virus. Cells that harbor viral DNA without M as integrated copies do not produce this protein, whereas cells that harbor integrated viral genomes which are defective for another E1 viral gene important for plasmid replication, R, do produce this protein. The protein has an anomalously low electrophoretic mobility. An in vitro translation product of an SP6 RNA product of a sequenced cDNA predicts a molecular mass of 16 kilodaltons for the protein, and this in vitro translation product has an electrophoretic mobility identical to that of the in vivo immunoprecipitated protein. The results of these studies confirm our previous genetic studies which indicated that part of the E1 open reading frame defined a discrete gene product distinct from other putative products which may be encoded by this open reading frame.

Bovine papillomavirus 1↗
PubMed1985

Organization, primary structure, and evolution of histone H2A and H2B genes of the fission yeast Schizosaccharomyces pombe.

The histone H2A and H2B genes of the fission yeast Schizosaccharomyces pombe were cloned and sequenced. Southern blot and sequence analyses showed that, unlike other eucaryotes, Saccharomyces cerevisiae included, S. pombe has unequal numbers of these genes, containing two histone H2A genes (H2A-alpha and -beta) and only one H2B gene (H2B-alpha) per haploid genome. H2A- and H2B-alpha are adjacent to each other and are divergently transcribed. H2A-beta has no other histone gene in close proximity. Preceding both H2A-alpha and -beta is a highly conserved 19-base-pair sequence (5'-CATCAC/AAACCCTAACCCTG-3'). The H2A DNA sequences encode two histone H2A subtypes differing in amino acid sequence (three residues) and size (H2A-alpha, 131 residues; H2A-beta, 130 residues). H2B-alpha codes for a 125-amino-acid protein. Sequence evolution is extensive between S. pombe and S. cerevisiae and displays unique patterns of divergence. Certain N-terminal sequences normally divergent between eucaryotes are conserved between the two yeasts. In contrast, the normally conserved hydrophobic core of H2A is as divergent between the yeasts as between S. pombe and calf.

Amino Acid Sequence↗
PubMed1982

The two yeast histone H2A genes encode similar protein subtypes.

The sequences of the two histones H2A genes in the yeast Saccharomyces cerevisiae have been determined. These genes encode two histone H2A subtypes which are 131 amino acids in length but differ at 2 amino acid positions: an Ala leads to Thr and a Thr leads to Ala change at positions 124 and 125. Thus, the two histone H2A subtypes have identical amino acid compositions. The coding regions of the two H2A genes are homologous at 369 of 393 bases (94%), with all but 2 of the 24 changes being silent. There is only 30% homology in the 5' flanking sequences of the two H2A genes. Like other eukaryotic histone genes, the yeast H2A genes are not interrupted by intervening sequences. When the yeast H2A histones are compared to those from other eukaryotes, there is at least 80% homology in amino acid sequence.

Amino Acid Sequence↗
PubMedDate not supplied

Parameters affecting the efficiency of affinity-based reversed micellar extraction and separation (ARMES) in glycoprotein purification.

Affinity-based reversed micellar extraction and separation (ARMES) is an effective method for purifying both low and high molecular weight glycoproteins via liquid-liquid extraction. A range of extraction conditions were examined to gain insight into the mechanism of ARMES. Concanavalin A (Con A) was used as the model affinity ligand to bind soybean peroxidase (SBP) and beta-galactosidase as model glycoproteins. Factorial design was used to investigate the effect of various system variables on the extraction of SBP via ARMES. A quadratic model described the systems well, resulting in a standard deviation of 7% between calculated and experimental extraction efficiencies. Sensitivity analysis suggested that the key criteria in ARMES were the NaCl concentration and pH of the aqueous feed phase. Extraction of both glycoproteins decreased above pH 7 but fell to zero only at pH values significantly above the pI of the model glycoproteins and the Con A affinity ligand. It is proposed that the complex of the affinity lectin with the glycoprotein results in a sufficiently hydrophobic species that can be extracted into a reversed micellar organic phase even at pH's far above the pI's of the individual proteins that comprise the complex. This finding has practical considerations for the use of ARMES in the resolution and purification of protein glycoforms.

Glycoproteins↗