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Biomedical subjects

H Yoon

Publications and source records attributed to H Yoon.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effect of pelvic floor muscle exercises on genuine stress incontinence among Korean women--focusing on its effects on the quality of life.

This study's purpose was to compare the treatment efficacy and the effects on the patients' quality of life of the pelvic floor muscle (PFM) exercise and the functional electrical stimulation (FES)-biofeedback method. Ninety female incontinence patients were randomly selected and evenly divided into three groups: control, intensive PFM exercise, and FES-biofeedback groups. They were treated for 6 weeks. The subjective changes in the severity of incontinence and discomfort in daily and social life were measured using a translated version of Jackson's Bristol female urinary symptom questionnaire. Objective changes of pelvic muscle contraction force were measured by perineometer. Pre and post-treatment maximal pelvic floor muscle contractile pressure (PMC pressure) among the three groups showed statistically significant differences (p < 0.001). Especially the FES-biofeedback group showed significantly increased maximal PMC pressure compared with other groups (p < 0.001). From the questionnaire, pre and post-treatment changes in the severity of urinary incontinence and discomfort due to incontinence showed significant differences among the three groups (p < 0.001). The level of discomfort in daily life, social activity, physical activity, personal relations and discomfort due to urinary symptoms had largely changed and the FES-biofeedback group, in particular, showed a significant decrease after treatment. In conclusion, when PFM exercise and FES-biofeedback were compared in terms of their effects on the patients' quality of life, FES-biofeedback proved to be more effective than verbal explanation or simple PFM exercise.

Adolescent↗
PubMed2000

Development of the lip and palate in staged human embryos and early fetuses.

Cleft lip and palate are the most common congenital malformations in humans. Using 43 staged human embryos and early fetuses ranging from the 4th to 12th week of development, we investigated the development of the lip and palate in order to provide the basic developmental concepts required for managing these anomalies. The lower lip appeared as bilateral mandibular arches at Carnegie stage 11, and these were completely merged at stage 15. The components of the upper lip, medial nasal prominence and maxillary process, appeared at stage 16, and completely merged at stage 20. The median palatine process appeared at stage 16, and the lateral palatine process, at stage 17. The palatine processes and the nasal septum started to fuse abruptly at stage 23, and from external observation seemed to be fused at the 9th week. However, complete fusion did not take place until the 12th week of development. The tongue was prominent at stage 16, showed differentiation of the muscular tissue at stage 21, and was located superior to the lateral palatine process before stage 23. These results may be used in understanding the different mechanisms present in the formation of various congenital anomalies in this region.

Female↗
PubMed2000

Systematic review of epidemiological studies on meat, dairy products and egg consumption and risk of colorectal adenomas.

In view of the direct contact between food residues and metabolites and the large bowel mucosa, it might be expected that food consumption patterns would affect the risk of colorectal carcinogenesis. Many lines of evidence support the adenoma-carcinoma sequence as the major mechanism of colorectal carcinogenesis. The present study aimed to investigate the role of foods of animal origin such as meat, dairy products and eggs in the early stages of colorectal carcinogenesis. Eleven case-control and two cohort studies on colorectal polyps and meat, dairy products and eggs were identified. A quantitative review of these studies and a meta-analysis were carried out. The combined odds ratios suggest a positive association between the risk of colorectal polyps and beef consumption and a negative association with fish or combined poultry/fish consumption. An increase in the ratio of the consumption of red meat to consumption of fish/chicken was associated with an increase in the colorectal polyp risk. Neither dairy product nor egg consumption had a substantial effect on the development of colorectal polyps. These results suggest that dietary factors associated with polyp development may be not the same as those associated with cancer.

Adenoma↗
PubMed1999

Cloning of the human monocarboxylate transporter MCT3 gene: localization to chromosome 22q12.3-q13.2.

Lactate transport across cell membranes is mediated by a family of proton-coupled monocarboxylate transporters (MCTs). The retinal pigment epithelium (RPE) expresses a unique member of this family, MCT3. A portion of the human MCT3 gene was cloned by polymerase chain reaction using primers designed from rat RPE MCT3 cDNA sequence. The human genomic sequence was used to design primers to clone human MCT3 cDNA and to identify a bacterial artificial chromosome clone containing the human MCT3 gene. The human MCT3 cDNA contained a 1512-nucleotide open reading frame with a deduced amino sequence 85% identical to rat MCT3. Comparison of the cDNA and genomic sequences revealed that the MCT3 gene was composed of five exons distributed over 5 kb of DNA. The exon-intron borders were conserved between the human and the chicken MCT3 genes. Using radiation hybrid mapping, the MCT3 gene was mapped to chromosome 22 between markers WI11639 and SGC30687. A search of chromosome 22 in the Sanger Centre database confirmed the location of the human MCT3 gene at 22q12.3-q13.2.

Animals↗
PubMed1999

Non-association of estrogen receptor genotypes with bone mineral density and bone turnover in Korean pre-, peri-, and postmenopausal women.

Estrogen is known to play a critical role in both skeletal maturity and the rate of bone loss. This suggests the possibility that the estrogen receptor (ER) gene is one of the candidate genes that determines peak bone density and/or bone turnover rate. We investigated two established restriction fragment length polymorphisms (RFLPs) in intron 1 at the ER gene, represented as PvuII and XbaI. In 598 healthy Korean women aged 20-74 years, we examined the association of these ER genotypes with bone mineral density (BMD) and bone turnover status. The distribution of the PvuII and XbaI RFLPs was as follows: pp 205 (34.3%), Pp 308 (51.5%), PP 85 (14.2%) and xx 384 (64.2%), Xx 180 (30.1%), XX 34 (5.7%), respectively (where capital letters signify the absence of, and lower-case letters signify the presence of, the restriction site of each RFLP). No significant genotypic differences were found in BMD and bone markers. We grouped the subjects into three categories according to their menstrual status: 104 premenopausal women with regular menstruation, 182 perimenopausal women who had amenorrhea of not less than 3 months and not more than 12 months' duration, and 312 postmenopausal women whose last menstruation was at least 12 months previously. No significant genotypic difference in either BMD or bone markers was found in any of these three groups. Furthermore we categorized women in peri- and postmenopause into a high loser group and a normal loser group according to the level of bone resorption markers. There was no difference in genotypic proportions between the high and normal loser groups. Our data suggest that these ER polymorphisms are not associated with BMD or bone turnover in Korean women.

Absorptiometry, Photon↗
PubMed1999

Incidence of hepatocellular carcinoma in transgenic mice expressing the hepatitis B virus X-protein.

BACKGROUND/AIMS: Chronic infection with hepatitis B virus is a high-risk factor for hepatocellular carcinoma in humans. The HBV X-protein, a multi-functional viral regulator, has been suspected to play a positive role in hepatocarcinogenesis, as demonstrated by the high incidence of hepatocellular carcinoma in HBx-expressing transgenic mice, although it is still controversial. The aim of this study was to generate transgenic mice expressing the HBV X-gene under authentic promoter control and to test whether the gene products can cause hepatic tumors. METHODS: Three transgenic mouse lines were generated by microinjecting the X-gene construct into hybrid (C57BL/6 x DBA) eggs. Gene expression was tested by protein and mRNA analyses. During an observation period of 18 months, mice were sacrificed and organs subjected to histologic examinations. RESULTS: Grossly defined hepatocellular carcinomas reproducibly were observed in mice expressing the X-protein, which were investigated through six generations from the age of 11 to 18 months. Among 14 transgenic mice investigated from the age of 11 to 18 months, 12 were found to have hepatocellular carcinoma, grossly or microscopically. The lesion of the hepatocellular carcinoma disclosed a significant increase in the proliferating cell nuclear antigen in the nuclei. CONCLUSION: The incidence of hepatocellular carcinoma (86%) in our HBV X transgenic mice may be highly significant, since, except for one case, HBV X-gene transgenic mice produced in other laboratories did not develop liver tumor or any other pathologic phenomena.

Animals↗
PubMed1999

Induction of cytotoxic T lymphocytes with peptides in vitro: identification of candidate T-cell epitopes in hepatitis B virus X antigen.

Cytotoxic T lymphocytes (CTL) have been suggested to contribute to viral clearance during hepatitis B virus (HBV) infection. To induce effective CTL against viral infection by peptide vaccination, it is essential to identify the epitope peptides recognized by CTL. Here, 15 peptide sequences that contain HLA-A2.1-restricted CTL binding consensus motif were identified on hepatitis B virus X (HBx) protein and synthesized for further characterization. In the binding assay, 8 of 15 synthetic peptides enhanced the expression of HLA-A2.1 molecules on the surface of T2 cells, a human transport-associated antigen processing-deficient cell line. This result implies that these eight peptides are able to bind to the HLA-A2.1 molecules. These peptides were further tested for their ability to activate CTL from peripheral blood mononuclear cells (PBMCs) isolated from HBV chronic carriers. Five of eight tested peptides activated PBMC-derived T cells, resulting in the lysis of the target T2 cells pulsed with the same peptide. Furthermore, the CTL responses to HBx antigen in HBV chronic carriers were shown to be polyclonal, multispecific, and mediated mainly by CD8+ T cells. In contrast, these responses were not detected in uninfected healthy blood donors. Although the five CTL epitope peptides identified in this study have not been proven to be the naturally processed epitopes in HBV-infected hepatocytes, they could be candidates for peptide-based immunotherapy against HBV infection.

Amino Acid Sequence↗
PubMed1998

Preferential interaction of the mRNA proofreading factor TFIIS zinc ribbon with rU.dA base pairs correlates with its function.

The transcriptional factor TFIIS helps overcome elongation barriers and enhances proofreading by RNA polymerase II. These TFIIS functions may be modulated by the TFIIS zinc ribbon domain through interactions with nucleic acids in the elongation complex. Within this zinc ribbon domain, the dipeptide sequences Asp261-Glu262 and Arg276-Trp277 have been shown to be critical for its function by mutant analysis. The sequence Asp261-Glu262 has been suggested to participate in metal binding within the RNA polymerase II active site. We now show that the sequence Arg276-Trp277 interacts with nucleic acids through a combination of electrostatic and stacking interactions. The interaction of the indole side chain of the tryptophan residue with nucleic acid bases is demonstrated by a characteristic and reversible decrease in the zinc ribbon fluorescence intensity as a function of oligonucleotide concentration. These interactions are salt sensitive (maximum interaction at 200 mM and no interaction at 500 mM NaCl), suggesting that the tryptophan stacking with nucleic acid base accompanies electrostatic contacts. The oligonucleotide-zinc ribbon interactions exhibit small but significant base preferences, as shown by the dependence of Keq on base composition, with decreasing Keq in the order U > T > A > C >> G. Within the variety of homopolymeric single- and double-stranded deoxy- and ribooligonucleotides, the oligonucleotide rU12-18.dA20 exhibited a 2-6-fold binding preference relative to other oligonucleotides. This preferential binding of the zinc ribbon to sequences composed of rU.dA base pairs, which are generally associated with elongation blocks, may help in overcoming elongation barriers. Since the mRNA proofreading and enhancement of elongation involve cleavage of ribonucleotide of the mismatched pair and the weakly paired rU.dA nucleotides, but not the stably paired rC.dG nucleotides, we propose that the Arg276-Trp277 sequence in the TFIIS zinc ribbon may serve as a scanner connected to the transcript cleavage apparatus for weakly paired or mismatched nucleotides by employing indole ring stacking with the bases as a criterion of determining their subsequent removal. The striking similarity in preference for mismatched and weakly paired nucleotides for binding and for excision suggests a functional relationship between binding and cleavage reactions.

Arginine↗
PubMed1998

Genomic structure and developmental expression of the chicken nonocarboxylate transporter MCT3 gene.

MCT3 is a monocarboxylate transporter that is specifically expressed on the basolateral membrane of retinal pigment epithelial cells (RPE). In these studies the temporal expression of MCT3 during ocular development was examined using Northern blot analysis. A 2.2 kb transcript (MCT3b) was detected in RPE by embryonic day 7 (E7) and was present throughout embryonic development. A 2.45 kb transcript (MCT3a) was expressed at low levels before E11 but its expression increased between E11 and E17. Using 5'-RACE (rapid amplification of cDNA ends) it has demonstrated that MCT3a and MCT3b mRNA had distinct 5'-untranslated sequences but shared the same translation start site. To determine the exon-intron structure and to understand the elements that control the tissue specific and developmental expression of MCT3, the MCT3 gene was cloned and sequenced from a chicken genomic library. The MCT3 gene is distributed over 8 kb of DNA and is composed of 6 exons. Coding sequences for MCT3 are found on exon 2 through exon 5. Comparison of the 5'-RACE sequence with the genomic sequence reveals that the two 5'-untranslated regions of the mRNAs are encoded by distinct exons, 1a and 1b, which are alternatively spliced to exon 2. These data suggest that two forms of MCT3 mRNAs could be generated by two distinct promoters that may be regulated in response to changes in the metabolic activity of the retina during development.

Amino Acid Sequence↗
PubMed1998

Retrospective biochemical screening of fatty acid oxidation disorders in postmortem livers of 418 cases of sudden death in the first year of life.

OBJECTIVE: Fatty acid oxidation (FAO) disorders are frequently reported as the cause of sudden and unexpected death, but their postmortem recognition remains difficult. We have devised a biochemical protocol in which informative findings in liver tissue are microvesicular steatosis, elevated concentrations of C8-C16 fatty acids, glucose depletion, and low carnitine concentration. STUDY DESIGN: We analyzed 27 cases representing five FAO disorders and compared the results with those obtained in a retrospective blinded analysis of 418 cases of sudden infant death (313 SIDS, 45 infections, and 34 accidents and abuse). RESULTS: All cases of accidents and abuse correctly tested negative. Among the others, 25 (6%) showed at least two abnormal findings. Of these, 14 closely matched the biochemical profiles seen in specific FAO disorders. These included 2 cases with medium-chain acyl-CoA dehydrogenase deficiency, 4 cases consistent with glutaric acidemia type 2, 4 cases with either very long-chain acylcoenzyme A dehydrogenase deficiency or long-chain 3-hydroxy-acyl-coenzyme A dehydrogenase deficiency, and 4 cases predicted to be affected with carnitine uptake defect. CONCLUSION: The results of this study support the view that approximately 5% of all cases of sudden infant death are likely caused by an FAO disorder.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1998

Synthetic peptides of human papillomavirus type 18 E6 harboring HLA-A2.1 motif can induce peptide-specific cytotoxic T-cells from peripheral blood mononuclear cells of healthy donors.

To identify cytotoxic T-cell (CTL) epitopes against human papillomavirus type 18 (HPV 18) E6 protein that might be useful for developing peptide-based vaccine against HPV 18 infection, 18 peptides which possibly contain CTL epitopes were selected on the basis of previously described human leukocyte antigen (HLA)-A2.1-binding motif and chemically synthesized. In the binding assay of the synthetic peptides, 8 out of 18 synthetic peptides enhanced the expression of HLA-A2.1 molecules on T2 cell surface, which implies that these peptides were able to bind the HLA molecules. Those peptides having good binding affinity to HLA-A2.1 were tested for their ability to activate CTLs which were isolated from peripheral blood mononuclear cells (PBMCs) of healthy blood donors and to kill the target T2 cells pulsed with the same peptide. Five out of eight tested peptides activated CTLs and killed the target cells.

Binding Sites↗
PubMed1998

Monocarboxylate transporter MCT1 is located in the apical membrane and MCT3 in the basal membrane of rat RPE.

The retinal pigment epithelium (RPE) forms the outer blood-retinal barrier and regulates the movement of nutrients, water, and ions between the choroidal blood supply and the retina. The transport properties of the RPE maintain retinal adhesion and regulate the pH and osmolarity in the space surrounding the photoreceptor cell outer segments. In this report we identify two monocarboxylate transporters, MCT1 and MCT3, expressed in rat RPE. On the basis of Northern and Western blot analyses, MCT1 is expressed in both the neural retina and the RPE, whereas the expression of MCT3 is restricted to the RPE. Using indirect immunolocalization we show that the two transporters are polarized to distinct membrane domains. MCT1 antibody labels the apical surface and the apical processes of the RPE. A polyclonal antibody produced against the carboxy terminus of rat MCT3 labels only the basolateral membrane of the RPE. The demonstration of MCT1 on the apical membrane and MCT3 on the basal membrane identifies specific proteins involved in the discriminate and critical regulation of water and lactate transport from the retina to the choroid.

Animals↗
PubMed1997

GTP hydrolysis controls stringent selection of the AUG start codon during translation initiation in Saccharomyces cerevisiae.

We have isolated and characterized two suppressor genes, SUI4 and SUI5, that can initiate translation in the absence of an AUG start codon at the HIS4 locus in Saccharomyces cerevisiae. Both suppressor genes are dominant in diploid cells and lethal in haploid cells. The SUI4 suppressor gene is identical to the GCD11 gene, which encodes the gamma subunit of the eIF-2 complex and contains a mutation in the G2 motif, one of the four signature motifs that characterizes this subunit to be a G-protein. The SUI5 suppressor gene is identical to the TIF5 gene that encodes eIF-5, a translation initiation factor known to stimulate the hydrolysis of GTP bound to eIF-2 as part of the 43S preinitiation complex. Purified mutant eIF-5 is more active in stimulating GTP hydrolysis in vitro than wild-type eIF-5, suggesting that an alteration of the hydrolysis rate of GTP bound to the 43S preinitiation complex during ribosomal scanning allows translation initiation at a non-AUG codon. Purified mutant eIF-2gamma complex is defective in ternary complex formation and this defect correlates with a higher rate of dissociation from charged initiator-tRNA in the absence of GTP hydrolysis. Biochemical characterization of SUI3 suppressor alleles that encode mutant forms of the beta subunit of eIF-2 revealed that these mutant eIF-2 complexes have a higher intrinsic rate of GTP hydrolysis, which is eIF-5 independent. All of these biochemical defects result in initiation at a UUG codon at the his4 gene in yeast. These studies in light of other analyses indicate that GTP hydrolysis that leads to dissociation of eIF-2 x GDP from the initiator-tRNA in the 43S preinitiation complex serves as a checkpoint for a 3-bp codon/anticodon interaction between the AUG start codon and the initiator-tRNA during the ribosomal scanning process.

Amino Acid Sequence↗
PubMed1997

Identification of a unique monocarboxylate transporter (MCT3) in retinal pigment epithelium.

The retinal pigment epithelium transports lactate between two tissue compartments, the interphotoreceptor matrix and the choriocapillaris. In this report we describe a 2.45-kb cDNA isolated from a chick cDNA RPE library that encodes a membrane protein found only in RPE cells. The deduced protein has 542 amino acids with twelve putative membrane spanning domains. The cDNA has been designated MCT3 based on its 45% identity in amino acid sequence and structural similarity with the monocarboxylate transporters MCT1 and MCT2. Stable transfectants (pCl-neo/MCT3), made in a rat thyroid epithelial cell line (FRTL-5), express MCT3 RNA. Transfectants had enhanced pyruvate uptake (used as a measure of lactate uptake) which was proton-dependent and inhibited by alpha-cyano-4-hydroxycinnamate. In summary, MCT3's unique expression in RPE cells, multiple potential phosphorylation sites, and basolateral distribution suggest that MCT3 may regulate lactate levels in the interphotoreceptor space.

Amino Acid Sequence↗
PubMed1997

The value of intraoperative cystoscopy in urogynecologic and reconstructive pelvic surgery.

OBJECTIVE: Our goal was to evaluate the role of intraoperative cystoscopy during surgery for pelvic organ prolapse and urinary incontinence. STUDY DESIGN: Charts of 224 consecutive patients who had intraoperative cystoscopy performed after urogynecologic surgery were reviewed. RESULTS: Nine injuries occurred that were unsuspected before cystoscopy, for an incidence of 4%. Six ureteral ligations occurred, four after Burch cystourethropexy and two after vaginal culdoplasty. Intravesical sutures were noted after two Burch procedures, and another injury occurred with passage of fascia lata through the bladder during a pubovaginal sling procedure. Eight injuries were managed by removal and replacement of the suture or sling with only one requiring ureteroneocystotomy. When patients with injuries were compared with those without, there were no statistical differences in demographic or surgical parameters. CONCLUSIONS: The potential for damage to the lower urinary tract is significant with complex urogynecologic surgery. Because of the increased and delayed morbidity associated with unrecognized injury, intraoperative surveillance cystoscopy should be considered a part of all such procedures.

Adult↗
PubMed1997

Factors affecting quality of life of the Korean aged stroke patients.

Among the most prevalent disabling diseases of old age, stroke is the leading chronic condition in Korea. The physical and psychosocial complications of a stroke can result in serious limitations on all aspects of one's life that affect overall quality of life. This study examines the relative importance of and interactions among factors which affect the quality of life of 119 stroke patients aged sixty-five and older in Korea. The model uses family support, personality (specifically hardiness), economic status, and physical functioning as independent variables, and quality of life as a dependent variable. The results of this study suggest that physical functioning and physical care by the family are important factors influencing quality of life of the aged stroke patients. Hardy personality is negatively associated with financial support and physical care by the family. These findings have several implications for policy development, clinical practice, and future research in this area.

Aged↗
PubMed1997

Morphological characteristics of the developing human brain during the embryonic period.

Many features of the developing nervous system are visible from external observations of intact human embryos. In this study, a photographic atlas from the 4th to the 7th week after ovulation (Carnegie stages 10-18) is provided. The neural folds began to fuse at stage 10, and the rostral and caudal neuropore were closed during stages 11 and 12, respectively. The three primary divisions of the brain were distinguishable before closing of the neural tube. The five secondary brain vesicles were formed during stages 14-15. The development of the cerebellum and cerebrum were first observed at stages 14 and 15, respectively. The mesencephalic flexure was seen at stage 12, and the cervical flexure and pontine flexure at stage 14. After stages 18-19, it became increasingly difficult to identify detailed features of the brain from the surface. Results from this study will help to correlate the characteristic findings of the developing central nervous system of human embryos from stereomicroscopical and light microscopical observations and to locate the exact parts of the developing human brain for other purposes.

Brain↗