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Y C Choi

Publications and source records attributed to Y C Choi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Mammalian male and female germ cells express a germ cell-specific Y-Box protein, MSY2.

Here we report the isolation and characterization of mouse testicular cDNAs encoding the mammalian homologue of the Xenopus germ cell-specific nucleic acid-binding protein FRGY2 (mRNP3+4), hereafter designated MSY2. MSY2 is a member of the Y box multigene family of proteins; it contains the cold shock domain that is highly conserved among all Y box proteins and four basic/aromatic islands that are closely related to the other known germline Y box proteins from Xenopus, FRGY2, and goldfish, GFYP2. Msy2 undergoes alternative splicing to yield alternate N-terminal regions upstream of the cold shock domain. Although MSY2 is a member of a large family of nucleic acid-binding proteins, Southern blotting detects only a limited number of genomic DNA fragments, suggesting that Msy2 is a single copy gene. By Northern blotting and immunoblotting, MSY2 appears to be a germ cell-specific protein in the testis. Analysis of Msy2 mRNA expression in prepubertal and adult mouse testes, and in isolated populations of germ cells, reveals maximal expression in postmeiotic round spermatids, a cell type with abundant amounts of stored messenger ribonucleoproteins. In the ovary, MSY2 is present exclusively in diplotene-stage and mature oocytes. MSY2 is maternally inherited in the one-cell-stage embryo but is not detected in the late two-cell-stage embryo. This loss of MSY2 is coincident with the bulk degradation of maternal mRNAs in the two-cell embryo.

Alternative Splicing↗
PubMed1998

The genomic and sequence analysis of rat histone H2B genes.

In addition to previously characterized testis-specific and somatic H2B histone genes, two somatic histone H2B genes, hereafter called sH2B-2 and sH2B-3, were isolated from a rat genomic library, genomic organization was determined, and their promoter was sequenced. Like many other H2B genes, sH2B-2 gene was closely linked to H2A gene whereas H3 gene was located upstream of sH2B-3 gene. Deletion and mutation analysis of 5' sequence fused to CAT reporter gene revealed that the interaction between CCAAT and octamer binding factors is important for S-phase-specific activation of sH2B-3 gene.

3T3 Cells↗
PubMed1997

Genomic analysis of the mouse protamine 1, protamine 2, and transition protein 2 gene cluster reveals hypermethylation in expressing cells.

To understand the role of chromatin structure in the expression of the mouse protamine 1, protamine 2, and transition protein 2 genes during spermatogenesis, we have examined the genomic organization of this cluster of "haploid-specific" genes. As seen in the human genome, protamine 2, transition protein 2, and approximately 2.8 kb of a CpG island, hereafter called CpG island-dTP2, were clustered in a small region. Methylation analyses of this region have demonstrated that i) unlike most other tissue-specific genes, the protamine 1, protamine 2, and transition protein 2 genes were located in a large methylated domain in round spermatids, the cell type where they are transcribed, ii) the protamine 1 gene was only partially methylated in somatic cells and in testes from 7-day-old mice, and iii) the approximately 2 kb upstream and downstream of the CpG island-dTP2 were only partially methylated in somatic tissues. DNase I analysis revealed the presence of at least five strong DNase I hypersensitive sites over the CpG island-dTP2 in somatic tissues, but not in germ cells, and sequence analysis indicated that the CpG island-dTP2 is homologous to a CpG island located approximately 10.6 kb downstream of the human transition protein 2 gene. Although the nature of a CpG island-dTP2 and the function of a CpG island-dTP2-containing somatic tissue-specific DNase I hypersensitive sites in close proximity to the germ cell-specific gene cluster are unclear, the "open" chromatin structure of the CpG island-dTP2 may be responsible for the partial methylation pattern of the flanking sequences including the transition protein 2 gene in somatic tissues.

Animals↗
PubMed1996

Sleep-related periodic leg movements associated with spinal cord lesions.

We describe three patients who developed progressive paraparesis and sleep-related periodic leg movements (SRPLM) associated with thoracic spinal cord lesions; one patient had a schwannoma and two had intramedullary lesions. The patients showed periodic repetitive involuntary movements involving one or both lower limbs. The involuntary movements consisted of a single rapid dorsiflexion of the great toe or ankle, two to four repetitive dorsiflexions of the toes and ankle, and a mixture of repetitive jerks and prolonged spasms causing flexion of the hip and knee and dorsiflexion of the ankle and toes. In the patient with a schwannoma, paraparesis and SRPLM improved completely after surgical removal of the mass lesion. In one patient the SRPLM associated with an intramedullary lesion improved markedly after levodopa treatment. We suspect that thoracic spinal lesions partially disinhibit the lumbosacral generator. Such disinhibition seems to be enhanced by the activation of the neuronal systems related to periodic somatic and vegetative phenomena during sleep.

Adult↗
PubMed1996

Molecular cloning of mouse somatic and testis-specific H2B histone genes containing a methylated CpG island.

We have isolated a mouse testis-specific H2B histone gene based on the unusual methylation of the CpG island of rat testis-specific H2B gene in somatic tissues. After digestion of genomic DNA with the methylation-sensitive restriction enzyme Hha I, we found that, among 10-20 copies of mouse H2B histone genes, at least three copies are methylated in somatic tissues, but not in testis. Cloning and sequence analysis of two methylated H2B genes revealed that one gene, MTH2B, is strikingly similar to the testis-specific histone H2B (TH2B) gene of rat and the other, psH2B, is a pseudogene of the somatic-type H2B gene. Northern blot analysis revealed that the expression of the MTH2B gene is testis-specific. During spermatogenesis, the MTH2B gene is expressed predominantly in pachytene spermatocytes, as observed in the expression of rat TH2B gene. Interestingly, the MTH2B gene is largely unmethylated in embryonic stem cells, but methylated in F9 embryonal carcinoma cells. The psH2B pseudogene is methylated in somatic tissues and F9 cells, but only partially methylated in embryonic stem cells. Methylation of the psH2B pseudogene seems to be attributed to its location within the context of repetitive sequences including the B1 element. The unmethylation of both H2B histone genes in the testis explains how CpG islands of those histone genes can be maintained during evolution despite heavy methylation in somatic tissues.

Amino Acid Sequence↗
PubMed1995

Regrowth of grafted human scalp hair after removal of the bulb.

BACKGROUND: The bulbar region of the hair follicle contains the dermal papilla, hair germinative epithelial component, and active melanocytes. Thus, it has been assumed that the bulbar region plays a central role in hair growth, differentiation, and pigmentation. OBJECTIVE: To assess the regenerative capacity of human hair. METHODS: Individual anagen hair follicles were isolated from the occipital scalp and grafted onto the leg after removal of the bulb. RESULTS: The grafts of follicles from which the bulb and complete papilla have been excised regenerated new papillae and grew new pigmented hairs. CONCLUSION: The middle portion of the outer root sheath and dermal sheath may also contain epithelial, mesenchymal, and melanocyte reservoirs.

Hair↗
PubMed1995

Evaluation of outcome of delayed neurologic sequelae after carbon monoxide poisoning by technetium-99m hexamethylpropylene amine oxime brain single photon emission computed tomography.

Using brain computed tomography (CT) and single photon emission computed tomography (SPECT) with technetium-99m hexamethylpropylene amine oxime (99mTc HM-PAO) in 13 patients with delayed neurologic sequelae after carbon monoxide poisoning, we tried to evaluate the clinical outcome of delayed CO sequelae. Among the 13 initial brain CTs, seven showed low density in the cerebral white matter and one revealed hypodensity in both globi pallidi. Of the 7 follow-up CT scans, 3 have remained unchanged, but in 4 cases more aggravating patterns with cortical atrophy without the clinical correlation were observed. There was no correlation between the CT findings and the outcome of delayed CO sequelae. All initial SPECTs in 13 patients with delayed CO sequelae showed diffuse patchy hypoperfusion throughout the cerebral cortex. Among the follow-up SPECTs in 7 patients, 6 patients showed increased cerebral perfusion with the concomitant clinical improvement, but the SPECT of a patient in bedridden state had remained unchanged, compared with the initial SPECT. There seemed to be good correlation between the findings of SPECT and the outcome of delayed CO sequelae. In conclusion, 99mTc HM-PAO brain SPECT is more sensitive than CT, and may be a useful test in evaluating the clinical outcome of delayed neurologic sequelae after CO poisoning.

Adult↗
PubMed1995

A clinical study of chronic headaches: clinical characteristics and depressive trends in migraine & tension-type headaches.

BACKGROUND & OBJECTIVES: Chronic headache is commonly encountered in the neurology outpatient clinic and it is often associated with depression. In Korea, however, chronic headache has not yet been systematically investigated. We conducted this study to investigate this clinical characteristics and level of depression in patients who presented migraine, tension-type headache, or transformed migraine. METHOD: Among those with chronic headache during the period from January 1, 1994 through December 31, 1994, 131 patients were diagnosed to have either migraine, tension-type headache (by IHS classification), or transformed migraine: migraine in 60 patients, tension-type headache in 49 patients, and transformed migraine in 22 patients. Beck Depression Inventory (BDI) was performed in 116 of the 131 patients. RESULTS & CONCLUSION: There was no significant difference in the age of onset, duration of headache, and family history among the three groups. However, patients with migraine had a more severe, unilateral, and throbbing characteristic pain than those with a tension-type headache. The mean BDI scores in the transformed migraine and the tension-type headache patients were significantly higher than those of migraine, but the level of depression did not correlate with the patient's age, duration, character, severity, and frequency of headache. These findings suggest that migraine, tension-type headache and transformed migraine may be considered clinically distinct entities in viewing their different clinical characteristics and level of depression.

Adolescent↗
PubMed1993

Demethylation of somatic and testis-specific histone H2A and H2B genes in F9 embryonal carcinoma cells.

In contrast to many other genes containing a CpG island, the testis-specific H2B (TH2B) histone gene exhibits tissue-specific methylation patterns in correlation with gene activity. Characterization of the methylation patterns within a 20-kb segment containing the TH2A and TH2B genes in comparison with that in a somatic histone cluster revealed that: (i) the germ cell-specific unmethylated domain of the TH2A and TH2B genes is defined as a small region surrounding the CpG islands of the TH2A and TH2B genes and (ii) somatic histone genes are unmethylated in both liver and germ cells, like other genes containing CpG islands, whereas flanking sequences are methylated. Transfection of in vitro-methylated TH2B, somatic H2B, and mouse metallothionein I constructs into F9 embryonal carcinoma cells revealed that the CpG islands of the TH2A and TH2B genes were demethylated like those of the somatic H2A and H2B genes and the metallothionein I gene. The demethylation of those CpG islands became significantly inefficient at a high number of integrated copies and a high density of methylated CpG dinucleotides. In contrast, three sites in the somatic histone cluster, of which two sites are located in the long terminal repeat of an endogenous retrovirus-like sequence, were efficiently demethylated even at a high copy number and a high density of methylated CpG dinucleotides. These results suggest two possible mechanisms for demethylation in F9 cells and methylation of CpG islands of the TH2A and TH2B genes at the postblastula stage during embryogenesis.

Animals↗
PubMed1993

Evaluation of outcome after acute carbon monoxide poisoning by brain CT.

Of 129 patients with carbon monoxide (CO) poisoning, 62(48.0%) had characteristic computed tomographic (CT) findings. The most common finding, seen in 42 patients, was low-density in the cerebral white matter, and the second characteristic feature, seen in 33 patients, was low-density in both globus pallidi. Abnormal CT findings tended to increase in accordance with the duration of unconsciousness during acute CO poisoning, but such findings occurred even when the mental state was clear during acute illness. The prognosis of acute CO poisoning depended on low-density lesions of the cerebral white matter rather than those of the globus pallidus. There also seemed to be a significant correlation between the cerebral white matter changes in the initial CT scan and the development of delayed neurologic sequelae after acute CO poisoning, particularly in middle age or older patients, but no correlation between the CT findings and the clinical outcome of delayed neurologic sequelae.

Acute Disease↗
PubMed1993

Delayed-onset focal dystonia after diffuse cerebral hypoxia--two case reports.

The delayed-onset focal dystonia is a rare sequela of cerebrovascular disease or diffuse cerebral hypoxic damage. The responsible lesion sites for the dystonia are variable and the pathogenesis is uncertain. We describe two children with delayed-onset focal dystonia as a complication of perinatal anoxia. The intervals between hypoxic insult and onset of dystonia were 6 years in one and 3 in the other cases. Our patients did not have a focal lesion; one had scattered white matter lesion and the other had a diffuse frontoparietal atrophy. Delayed-onset dystonia after perinatal anoxia can be also caused by non-focal lesion such as diffuse frontoparietal atrophy or cerebral white matter lesion with long interval delay.

Child↗
PubMed1993

Eye movement changes in albinism--a case report with electronystagmographic findings.

Albinism is associated with neural anomalies including foveal hypoplasia and aberrant optic pathway projection that result in a variety of oculomotor instability. We present a 38-years-old man with oculocutaneous albinism who had horizontal jerk-type nystagmus, which showed a reverse in direction by any extraneous light stimulation which was documented by electronystagmogram. The mechanism of the nystagmus in this case is uncertain. These findings in albinism have not been reported previously, to our knowledge, and suggest a defect in the visual pathway system.

Adult↗
PubMed1993

Delayed-onset focal dystonia after stroke.

The delayed-onset focal or segmental dystonia is a rare sequelae of cerebrovascular disease. The responsible lesion sites for the dystonia are variable and the pathogenesis is uncertain. This study reports three patients with delayed-onset focal dystonia as a complication of stroke. The interval between hypoxic insult and onset of dystonia were varied from 1 month to 1 year. Two adults and one child had focal lesions at the contralateral basal ganglia. The interval between the brain damage and dystonia did not appear to be related to the age at the time of hypoxic injury. The site of lesions may serve as an important factor in the pathogenesis.

Cerebrovascular Disorders↗
PubMed1992

Single hair transplantation using the Choi hair transplanter.

A new procedure for single hair transplantation using the Choi hair transplanter is presented. This operation provides obvious cosmetic advantages in hairline refinement and the reconstruction of eyebrows, eyelashes, beards, and pubic escutcheon. The surgical technique is described in detail.

Dermatology↗
PubMed1991

DNA hypomethylation and germ cell-specific expression of testis-specific H2B histone gene.

Testis-specific H2B (TH2B) histone gene of rat is expressed during meiotic event of spermatogenic differentiation. The gene is unusual in that it has conserved the regulatory elements involved in the S phase-specific transcription of somatic H2B genes as well as the S phase-specific stabilization of histone mRNA. Genomic sequencing revealed that all analyzed CpG sites in the promoter region of TH2B gene are methylated in somatic tissues but not in testis. During spermatogenesis, these CpG sites are unmethylated as early as spermatogonia type A and up to sperm. Thus, there is a good correlation between DNA hypomethylation and germ cell-specific expression of TH2B gene. Results obtained from in vivo DNase footprinting and DNA mobility shift experiments are consistent with the hypothesis that DNA methylation inhibits gene activity by preventing the binding of transcription factors to their recognition sequences. The results show that (i) the binding of ubiquitous transcription factors to the promoter region of TH2B gene may be blocked in nuclei of liver, and (ii) DNA methylation can directly interfere with the binding of transcription factors recognizing a hexamer (ACGTCA) motif. In vitro DNA methylation and transfection experiments demonstrated that expression of TH2B gene is inhibited by DNA methylation in vivo. These findings indicate that DNA methylation may play a key role in the transcriptional repression of germ cell-specific TH2B gene.

Animals↗
PubMed1991

Isolation of virus-like (VL30) elements from the Q10 and D regions of the major histocompatibility complex.

Previous studies from our laboratory have described two endogenous provirus-like sequences in a series of cosmids spanning the TL region of the major histocompatibility complex (MHC) of normal C57BL/10 mice. At least one of these viruses shares similarities with VL30 elements. To determine if additional VL30-like retroviral elements are integrated in the MHC, we constructed a cosmid library using DNA from a radiation leukemia virus (RadLV)-transformed cell line derived from C57BL/6 mice. The library was first screened using the H-2III (5') probe, which detects Class I genes of the H-2 complex. In the primary screening 163 H-2III positives were isolated. The H-2III-positive isolates were then hybridized with an AKR-derived virus probe, EcoB/S, which contains sequences from both the pol and the env genes of the virus. Nine virus-positive isolates were detected. Localization of these cosmid isolates containing viral sequences within the H-2 complex was done utilizing low-copy probes and confirmed using previously mapped cosmid isolates from other laboratories. We report here the isolation and characterization of VL30-like elements from the Qa and D regions of the MHC of several inbred mouse strains.

AKR murine leukemia virus↗