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Biomedical subjects

S H Kang

Publications and source records attributed to S H Kang.

At least 91 records · Page 5Linked to original sources
PubMed1995

Acute increase of GABAergic neurotransmission exerts a stimulatory effect on GnRH gene expression in the preoptic/anterior hypothalamic area of ovariectomized, estrogen- and progesterone-treated adult female rats.

Although gamma-aminobutyric acid (GABA) is known to play an important role in the regulation of GnRH release from the hypothalamus, GABAergic action on hypothalamic GnRH gene expression is poorly understood. The present study aims to evaluate the effects of several GABAergic compounds on GnRH mRNA and serum LH levels at the times of LH surge induced by estrogen plus progesterone treatment in long-term ovariectomized adult rats. Animals received either aminooxyacetic acid (AOAA, an inhibitor of GABA catabolism, i.p.), muscimol (GABA-A type agonist, i.c.v.) or baclofen (GABA-B type agonist, i.c.v.) 2 h prior to sacrifice. GnRH mRNA in the preoptic/anterior hypothalamic area and serum LH levels were determined by Northern blot analysis and LH radioimmunoassay, respectively. All of three GABA mimetics blocked the LH surge induced by estrogen plus progesterone in a dose-dependent manner. However, inhibition of GABA catabolism with AOAA in a dose range of 10-100 mg/kg b.w. increased GnRH mRNA level by 30%. Activation of GABA-A receptor with muscimol at a low dose (5 nmol) but not at high doses (10 and 30 nmol) elevated GnRH mRNA levels by 60% over the control value. Activation of GABA-B receptor with baclofen augmented GnRH mRNA levels in a dose-dependent manner. These observations indicate that acute increase of GABAergic neurotransmission may differentially regulate the release and GnRH gene expression depending on its receptor subtypes.

Aminooxyacetic Acid↗
PubMed1995

Constitutive activation of different Jak tyrosine kinases in human T cell leukemia virus type 1 (HTLV-1) tax protein or virus-transformed cells.

HTLV-1 infection causes an adult T cell leukemia in humans. The viral encoded protein tax, is thought to play an important role in oncogenesis. Our previous data obtained from a tax transgenic mouse model revealed that tax transforms mouse fibroblasts but not thymocytes, despite comparable levels of tax expression in both tissues. Constitutive tyrosine phosphorylation of a 130-kD protein(s) was observed in the tax transformed fibroblast B line and in HTLV-1 transformed human lymphoid lines, but not in thymocytes from Thy-tax transgenic mice. Phosphotyrosine immunoprecipitation followed by Western blot analysis with a set of Jak kinase specific antibodies, identified p130 as Jak2 in the tax transformed mouse fibroblastic cell line and Jak3 in HTLV-1 transformed human T cell lines. Phosphorylation of Jak2 in tax transformed cells resulted from high expression of IL-6. Tyrosine phosphorylation of this protein could also be induced in Balb/c3T3 cells using a supernatant from the B line, which was associated with induction of cell proliferation. Both phosphorylation and proliferation were inhibited by IL-6 neutralizing antibodies. Constitutive phosphorylation of Jak kinases may facilitate tumor growth in both HTLV-1 infected human T cells and the transgenic mouse model.

3T3 Cells↗
PubMed1995

The first documentation of Li-Fraumeni syndrome in Korea.

Li-Fraumeni syndrome(LFS) is an autosomal dominant disorder that predisposes individuals to multiple forms of cancer including breast cancer, soft tissue sarcoma, brain tumor, osteosarcoma, leukemia, and adrenocortical carcinoma. Recently, germ-line mutation of the p53 tumor suppressor gene has been implicated in this familial disorder. We report a case of a 25-year old woman who presented with bilateral breast cancer and uterine leiomyoma. Her mother had died of early-onset bilateral breast cancer. And her younger sister had breast carcinoma as well, which was identified at the age of 22, indicating her strong familial history. To test for the presence of the p53 germ-line mutation, we analyzed the genomic DNA from the peripheral blood of the proband and her sister by PCR-SSCP analysis of exon 5 through exon 8 of the p53 gene. As a result, a p53 mutation in exon 7 was detected in an allele, and it was shared with her sister as the same pattern. Sequencing analysis determined the altered nucleotide at codon 248(CGG > TGG) which is one of the most frequent mutation sites related to LFS. Therefore, this patient has the most consistent characteristic features of LFS phenotype and it is believed that this case is the first report of a family with Li-Fraumeni syndrome carrying the p53 germ-line mutation in Korea.

Adult↗
PubMed1994

Effect of phosphorothioate modification of oligodeoxynucleotides on specific protein binding.

Phosphorothioate modification of internucleoside linkages is widely used to prevent degradation of oligodeoxynucleotide (ODN) therapeutic agents in serum and cells. This modification generally increases ODN potency, but in many instances it is associated with an increase of poorly understood nonspecific effects. In this study, we have found that both cellular retention and nonspecific protein binding are dependent upon the extent of the oligonucleotide's modification. Flow cytometry of cells treated with fluorescein-labeled single-stranded (ss) or double-stranded (ds) ODNs demonstrated that fully phosphorothioate-modified ODNs exhibit much greater cellular association than 3'-terminally modified ODNs (with three 3'-terminal phosphorothioate linkages). Additionally, gel shift assays with either ss- or ds-probes showed that fully phosphorothioate-modified ODNs also exhibit much greater cytoplasmic and nuclear protein binding than either 3'-terminally modified or unmodified ODNs. However, gel shift competition assays showed that transcription factor binding by fully phosphorothioate-modified ds-ODNs was completely nonspecific relative to 3'-terminally modified and unmodified ds-ODNs. These results suggest that the benefits derived from full phosphorothioate modification of ODNs may be negated by increases of nonspecific protein binding and associated sequence-independent effects.

3T3 Cells↗
PubMed1994

Cancer screening among African-American women: their use of tests and social support.

This study examined associations between social ties (as measured by the Social Network Index), instrumental and emotional support, and the use of three female cancer screening tests: mammography, cervical smear, and clinical breast examination. Data were taken from a household survey of 670 African-American women living in northern California in 1986. In multiple logistic regression models, Berkman's index was associated with increased use of mammography but not with the use of cervical smear or clinical breast examination. Instrumental and emotional support measures were not significant. These results suggest that social networks may have a role in early cancer detection.

Adult↗
PubMed1993

Social support and cancer screening among older black Americans.

BACKGROUND: Age-adjusted cancer mortality is 27% higher for Black Americans than for the general U.S. population, which may result from inappropriate use of cancer detection tests. Social support has been shown to affect adjustment to breast cancer and survival, but it has not been studied as a predictor of use of preventive health care services in the older population. Our hypothesis is that larger social networks are associated with greater utilization of cancer-screening tests in the older population. PURPOSE: The objective of this study was to examine the relationship between social support and use of cancer-screening tests among older Black Americans. METHODS: Data for this study were obtained from a 1986 baseline survey evaluation of a community intervention program to increase cancer awareness and a 1991 end-point survey of use of cancer detection tests. Our study sample consisted of 617 Black Americans aged 55 years or older who lived in San Francisco (Calif.), the control community, and in Oakland (Calif.), the target community for intervention. The survey included measures of 1) social network characteristics, as determined by a modified version of Berkman and Syme's Social Network Index; 2) demographic characteristics; and 3) use of six cancer-screening tests--mammography, occult blood stool examination, cervical smear, clinical breast examination, digital rectal examination, and sigmoidoscopy. RESULTS: Multiple logistic regression analysis of the Social Network Index results indicated statistically significant positive associations of social support with the use of mammography and occult blood stool examination but not with the other cancer-screening tests. There were statistically significant associations between having HMO (Health Maintenance Organization) insurance and increased use of mammography and occult blood stool examination, compared with having Medi-Cal or other insurance. The interval between the surveys had a statistically significant positive association with use of mammography. These significant associations were not explained by differences in the other variables, which included health status, age, gender, education, type of health insurance, interval between the surveys, and a regular source of care. CONCLUSIONS: Social support seems to be associated with increased use of mammography and occult blood stool examinations among older Black Americans. IMPLICATIONS: Interventions designed to increase utilization of social networks may be an effective way to increase use of cancer screening, which may ultimately lead to reduced mortality from cancer.

Black or African American↗
PubMed1992

Glucose-6-phosphate dehydrogenase deficiency--report of 4 cases.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common hereditary enzyme disorder and more than 200 million people have a deficiency in this enzyme. It is a globally important cause of neonatal jaundice and causes life-threatening hemolytic crisis in childhood. At later ages, certain drugs such as antimalarials, and fava beans cause hemolysis among G6PD deficiency patients. The frequency and severity is influenced by genetic and cultural factors. It is common in Mediterranean, African, and some East Asian populations but rare in Korea. Four cases of G6PD deficiency which were first noticed in Korea are investigated with their clinical features.

Child↗
PubMed1991

Hodgkin's disease in a child with acute lymphoblastic leukemia.

Hodgkin's disease, manifested as a second malignant neoplasm in acute lymphoblastic leukemia, rarely occurs, with seventeen cases reported including this cases. We presented the clinical and pathological features of a nine-year-old male child with acute lymphoblastic leukemia in remission. He had cervical lymph node involvement 22 months after the diagnosis of leukemia as an initial presentation of Hodgkin's disease of mixed cellularity. A brief review of related literatures was also done.

Antineoplastic Agents↗
PubMed1990

Training and development of psychotherapy in Korea.

In this paper, the author presented the assimilation and development of Western psychotherapy in Korea in their historical perspectives since the introduction of Western psychoanalysis and dynamic psychotherapy to Korean cultural soil. The author also described in detail the present status of psychotherapy training in Korea. The philosophical goal of training and development of Korean psychotherapy has been and will be to unify and integrate Western psychotherapy and traditional Eastern Tao (Confucianism, Buddhism and Taoism) which, the author believes, is the highest form of psychotherapy.

Cross-Cultural Comparison↗
PubMed1989

Isolation and expression of a cDNA clone encoding HLA-Cw6: unique characteristics of HLA-C encoded gene products.

The HLA-C encoded gene products display several characteristics which distinguish them from HLA-A and -B. The HLA-C antigens are poorly expressed on the cell surface, they display multiple proteins with different isoelectric points, and alloimmunization to HLA-C antigens is less common. To investigate whether the multiple products result from differential splicing of HLA-C gene transcripts, we have isolated a full-length cDNA clone encoding the Cw6 antigen. Class I antigens produced by the cDNA clone in transfected cells were of the same relative mass as those observed in the parental cells when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing (IEF) gel analysis of the cDNA translated products in transfectants revealed multiple IEF bands. All IEF bands detected in the transfectants were also found in the parental cells, indicating that the multiplicity of the C-locus products was not due to differential splicing of HLA-C gene transcripts, but was probably due to post-translational modification. Comparison of the sequences of C-locus alleles with those of A and B alleles did not show any apparent sequences which would generate multiple IEF bands. Comparison of the coding regions for seven HLA-C alleles and one HLA-C-related class I gene with available data for 15 HLA-A and 20 HLA-B alleles demonstrated several unique features for the HLA-C locus. Six sites in the extra cellular domains, three in a1 and three in a3, were unique. While the cytoplasmic (CP) domain of HLA-A and -B are almost identical, the CP of HLA-C alleles is unique. Similar unique features of HLA-C are also observed in the transmembrane domain, resulting in locus-specific residues between positions 295 and 300. The present study has ruled out differential mRNA splicing as a mechanism for the multiplicity of Cw6 antigens and demonstrated unique HLA-C locus sequences.

Amino Acid Sequence↗
PubMed1989

Molecular mapping of a new public HLA class I epitope shared by all HLA-B and HLA-C antigens and defined by a monoclonal antibody.

It has previously been shown that a mouse monoclonal antibody, designated 4E, reacts with an epitope common to all HLA-B and -C antigens and those of the HLA-Aw19 cross-reactive group, namely, HLA-A29, -A30, -A31, -A32, -Aw33, and -Aw74. In order to pinpoint the amino acid residues which comprise the public specificity recognized by 4E, and HLA-A29 cDNA clone was isolated and its predicted amino acid sequence compared with those of other cloned HLA class I genes. The isolated HLA-A29 cDNA corresponded to the rarer of the two A29 variant alleles, A29.1. Two amino acid residues of HLA-A29.1, gln-144 and arg-151, were found in all 24 HLA-B and HLA-C alleles examined but were present in only one of 15 HLA-A alleles for which sequence data are available. Importantly, this exceptional allele was HLA-A32, another member of the HLA-Aw19 cross-reactive group. Gln-144 and arg-151 should be capable of jointly contributing to the binding site for 4E, as they are situated in successive alpha-helical subregions and are predicted to be juxtaposed in the three-dimensional HLA molecule. Four other residues in the first or second external domains of HLA-A29.1 (thr-9, leu-62, gln-63, and his-102) were unique among the HLA-A alleles, but none of these was found in corresponding positions of HLA-B of -C alleles and thus failed to correlate with presence or absence of the 4E determinant. These observations are consistent with the notion that gln-144 and arg-151 define a determinant common to HLA-B, HLA-C, and the HLA-Aw19 cross-reactive group and the binding site of the monoclonal antibody 4E.

Amino Acid Sequence↗
PubMed1989

A comprehensive study of immunological abnormalities in Korean hemophiliacs.

To determine laboratory evidence suggesting immunological abnormalities in persons with hemophilia, we evaluated the immunological status of 75 Korean hemophiliacs, seronegative for human immunodeficiency virus (HIV) antibodies, who have been treated only with Korean factor VIII concentrates. From this study, it was shown that Korean hemophiliacs had decreased CD4 levels, increased CD8 levels, and decreased CD4:CD8 ratios. Diminished lymphocyte response to the mitogens, phytohemagglutinin and concanavalin A, and decreased natural killer cell activity were observed in the hemophiliacs. In addition, production of interleukin-II in the hemophiliacs was lower than in the healthy controls. The percentage of B lymphocytes was significantly reduced but the serum levels of immunoglobulin (Ig) G were elevated. However, the serum Ig A and Ig M levels were normal. This study demonstrated a high frequency of immunological abnormalities in HIV antibody negative Korean hemophiliacs treated only with domestic factor VIII concentrates.

Adolescent↗
PubMed1982

Purification, composition, and physical properties of a thermal hysteresis "antifreeze" protein from larvae of the beetle, Tenebrio molitor.

Proteins which produce a thermal hysteresis (difference between the freezing and melting points) in aqueous solution are well-known for their antifreeze activity in polar marine fishes. Much less is known about the biology and biochemistry of similar antifreeze proteins found in certain insects. A thermal hysteresis protein was purified from cold acclimated larvae of the beetle, Tenebrio molitor, by using ethanol fractionation, DEAE ion-exchange chromatography, gel filtration, and high-pressure liquid chromatography. The purified protein had a molecular mass of 17 000 daltons and its N terminus was lysine. The amino acid composition of the antifreeze protein contained more hydrophilic amino acids than the fish antifreezes. This is consistent with the compositions of previously purified insect thermal hysteresis proteins. However, the percentage of hydrophilic amino acids in this Tenebrio antifreeze protein was considerably less than that of other insect thermal hysteresis proteins. The freezing point depressing activity of the Tenebrio antifreeze was less than that of fish proteins and glycoproteins at low protein concentrations but was greater at high protein concentrations.

Amino Acids↗