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Biomedical subjects

D Kang

Publications and source records attributed to D Kang.

At least 91 records · Page 5Linked to original sources
PubMed1998

Gene therapy targeting cord blood-derived CD34+ cells from HIV-exposed infants: preclinical studies.

Hematopoietic CD34+ cells from placental and umbilical cord blood (PUCB) can be valuable vehicles for gene therapy of immunodeficiencies and genetic disorders. We have conducted preclinical studies towards the treatment of HIV-1-infected infants with genetically 'immunized' CD34+ cells derived from PUCB using anti-HIV-1 hairpin ribozyme genes. PUCB was collected from 10 newborns of HIV-1-positive mothers. CD34+ cells were enriched with a modified procedure using Dynal immunomagnetic beads and chymopapain, stimulated with stem cell factor (SCF), IL-3 and IL-6, and transduced using cell-free recombinant retroviral vector (MJT) expressing a ribozyme against the U5 region of HIV-1. No significant differences were observed in the growth pattern of CD34+ cells from normal infants, HIV-1 exposed infants or infants confirmed to be infected by HIV-1. The transduction efficiency of the CD34+ cells from all the infants was also comparable. MJT-transduced CD34+ cells from an HIV-1-infected infant were maintained in a liquid culture system for 4 weeks, and the progeny macrophage cells were challenged with the monocyte-tropic laboratory strain, HIV-Bal, or the HIV-1 isolate from the infant's mother. Significant inhibition of virus replication was observed in ribozyme-transduced cells. Thus, we have demonstrated efficient and stable gene transfer into progenitor cells from the cord blood of HIV-1-exposed or -infected infants and shown that protection from HIV-1 infection was conferred to the progeny cells produced by CD34+ cells transduced with the anti-HIV ribozyme gene construct.

Antigens, CD34↗
PubMed1998

Female sex hormones and body mass in adolescent and postmenopausal Korean women.

A cross-sectional study was conducted to evaluate the relationship between body mass and serum level of female sex hormones among 153 adolescent girls, and 153 postmenopausal women in Korea. Information on lifestyles, and both menstrual and reproductive factors was collected by personal interview. Serum total estradiol (E2), progesterone (Pg), and sex hormone binding globulin (SHBG) concentrations were measured by radioimmunoassay. Multiple linear regression analysis was used to determine whether the hormonal levels would be affected by the obesity indices. Body weight and body mass index (BMI) were inversely related to SHBG level in both premenopausal (p<0.005) and postmenopausal women (p<0.005) after adjusting for age. E2 levels during any phase in premenopausal girls were not related to BMI, whereas heavier girls had significantly higher levels of late luteal-phase Pg (p<0.05). Taller postmenopausal women had lower E2 levels (p<0.05). Results on the association between SHBG and BMI are consistent with previous results in Caucasian women, and might suggest the potential role of bioavailable estradiol in breast carcinogenesis in pre- and post-menopausal women. The finding that progesterone might be related to body mass in premenopausal women should be pursued in further studies.

Adolescent↗
PubMed1998

Excitatory amino acids in cerebrospinal fluid and their relations with clinical features and outcomes in acute head injury.

OBJECTIVE: To determine the contents and dynamics of excitatory amino acids (EAAs), glutamate (GLU) and aspartate (ASP) in the cerebrospinal fluid (CSF) of patients with acute head injury and to clarify the relationship of EAAs with clinical features and outcomes. METHODS: Forty-two adults with acute head injury were included. Glasgow coma scale (GCS) obtained at admission and Glasgow outcome scale (GOS) obtained three months post-injury were assessed. Samples of CSF were obtained via ventricular or lumbar puncture every 24 hours. GLU and ASP in CSF were analyzed by reversed-phase HPLC with a fluorescent detector. Nine control subjects were adults with lumbar anesthesia but without neurological diseases. RESULTS: The peak concentration of GLU and ASP of head-injured group was significantly higher than that of the control group. Dynamic research on severely injured ones indicated that the peak value of GLU mostly appeared within 48 hours post-injury; it decreased with the improving or remaining of the neurological status, and increased with the deterioration, but was still higher than that of the control seven days post-injury. The peak value of EAAs of severely injured patients was conspicuously higher than that of mildly injured group. There was a significant negative correlation between the peak values of GCS and EAAs. The peak value of EAAs in patients with poor outcome was remarkably higher than that in patients with good outcome. GOS was closely correlated to the peak value of EAAs. When the concentration of GLU was over 7 mumol/L, the rate of poor-outcome increased markedly. CONCLUSION: The content of EAAs in CSF increases following acute head injury and remains higher at least a week post-injury in severely injured patients. The more severe the trauma, the more obvious the excitotoxicity induced by EAAs; the more serious the secondary brain insult and the brain edema will be, the worse the outcome, naturally.

Adolescent↗
PubMed1998

Cotransduction of tyrosine hydroxylase and aromatic L-amino acid decarboxylase genes into cultured striatal cells using adeno-associated virus vectors.

OBJECTIVE: To examine whether tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) genes can be cotransduced into the same target striatal cells using adeno-associated virus (AAV) vectors, and to determine whether the cotransduction would result in better biochemical change than the TH gene alone. METHODS: TH and AADC genes were cotransduced into cultured striatal cells with separate AAV vectors. Expressions of TH and AADC were detected by immunocytochemistry; intracellular catecholamine levels were assayed by high-performance liquid chromatography (HPLC). RESULTS: TH and AADC genes were efficiently cotransduced into the striatal cells. Specifically, the coexpression of TH and AADC resulted in more effective dopamine production compared with the TH gene alone. CONCLUSION: Using AAV vectors, coexpression of TH and AADC in the striatal cells might be a useful approach to gene therapy for Parkinson's disease.

Animals↗
PubMed1998

New sensitive method for the detection of the A3243G mutation of human mitochondrial deoxyribonucleic acid in diabetes mellitus patients by ligation-mediated polymerase chain reaction.

An adenine-to-guanine mutation at nucleotide position (np) 3243 in the mitochondrial tRNALeu(UUR) gene is closely associated with various clinical phenotypes of diabetes mellitus. Because the mutation creates a new restriction site for the restriction enzyme ApaI, the mutation is usually detected and quantified by ApaI cleavage of the PCR products including np 3243. The sensitivity of the conventional method is, however, 5-10% heteroplasmy. The percentage of heteroplasmy of the mutation is usually highest in the affected tissues and is much lower in peripheral blood cells, which are used most frequently for the analysis. The sensitivity of the conventional method, however, is not sufficient to detect the mutation from peripheral blood cells. Utilizing ligation-mediated polymerase chain reaction, we have developed a feasible and sensitive method to detect 0.01% heteroplasmy of the 3243 mutation in peripheral leukocytes.

Adenine↗
PubMed1997

Reversible ischemia increases levels of Alzheimer amyloid protein precursor without increasing levels of mRNA in the rabbit spinal cord.

In a rabbit spinal cord ischemia model (RSCIM), the time courses of neuropathological damage of the spinal cord and neurological impairment of the motor functions are well established, demonstrating that the extent of neuropathological damage and the severity of neurological impairment are closely correlated. We used the RSCIM to elucidate the effects of reversible (15 min) and irreversible (60 min) ischemia on the endogenous levels of amyloid protein precursors (APPs) at both the mRNA and protein levels in the caudolumbar/sacral region of the spinal cord. We speculate that endogenous APPs are induced by ischemia as either trophic factors or stress-induced proteins in the RSCIM. A 15-min occlusion transiently increased the APP protein levels in neurons, which returned to the original levels by the end of 60 min occlusion. The increase in APP protein levels during 15-min ischemic insult does not appear to involve regulation at the mRNA level. The increased level of APPs, particularly of the soluble form, could support the possibility that APPs play a neuroprotective role in the RSCIM as stress-induced proteins. In contrast, failure to maintain the increased APP protein levels or to increase the mRNA, as seen in the 60-min ischemia samples, may be one of the causal factors that induce necrosis and neuronal cell death leading to irreversible neurological impairment.

Amyloid beta-Protein Precursor↗
PubMed1997

p32 protein, a splicing factor 2-associated protein, is localized in mitochondrial matrix and is functionally important in maintaining oxidative phosphorylation.

Human p32, originally cloned as a splicing factor 2-associated protein, has been reported to interact with a variety of molecules including human immunodeficiency virus Tat and complement 1q (C1q). p32 protein is supposed to be in the nucleus and on the plasma membrane for the association with human immunodeficiency virus Tat and C1q, respectively. None of the interactions, however, is proven to have a physiological role. To investigate the physiological function of p32, we determined the intracellular localization of p32. The fractionation of cells, fluorescent immunocytochemistry, and electron microscopic immunostaining show that p32 is exclusively localized in the mitochondrial matrix. We cloned a Saccharomyces cerevisiae homologue of human p32 gene, referred to yeast p30 gene. The yeast p30 protein is also localized in the mitochondrial matrix. The disruption of the p30 gene caused the growth retardation of yeast cells in a glycerol medium but not in a glucose medium, i.e. the impairment of the mitochondrial ATP synthesis. The growth impairment was restored by the introduction of the human p32 cDNA, indicating that p30 is a functional yeast counterpart of human p32. Taken together, both p32 and p30 reside in mitochondrial matrix and play an important role in maintaining mitochondrial oxidative phosphorylation.

Amino Acid Sequence↗
PubMed1997

In vivo determination of replication origins of human mitochondrial DNA by ligation-mediated polymerase chain reaction.

A large part of replication is aborted in human mitochondria, the result being a D-loop. As few attempts have been made to distinguish free 5' ends of true replicate from those of abortive ones, we examined the 5' ends of true replicate of human mitochondrial DNA at one nucleotide resolution in vivo by making use of ligation-mediated polymerase chain reaction. The distribution and relative amounts of origins of the true replicate are exactly the same as those of total newly synthesized heavy strands, which means that the abortion of replication is independent of 5' ends. Treatment of DNA with RNase H frees 5' ends on both heavy and light strands. This is the first in vivo evidence for covalently attached primer RNA to nascent strand in human mitochondrial DNA.

DNA Replication↗
PubMed1997

Interactions between superoxide and nitric oxide: implications in DNA damage and mutagenesis.

Chronic inflammation is known to be associated with enhanced production of both nitric oxide (NO) and reactive oxygen species such as superoxide (O2-) and hydrogen peroxide (H2O2). Patients with long-standing ulcerative colitis are also known to be at increased risk of developing colorectal cancer. Although NO and reactive oxygen intermediates alone have been known to damage DNA and to promote a wide array of mutagenic reactions, there is increasing evidence to suggest that the interaction between O2- and NO may dictate the type of mutagenic reactions produced at sites where both these free radicals are produced. In the absence of O2-, NO will engage in nitrosative chemistry to yield stable N-nitrosamine derivatives of secondary amines and promote nitrosative deamination of DNA bases. As the flux of O2- is increased, nitrosation reactions are suppressed and oxidative chemistry is enhanced. Thus, depending upon the fluxes of each radical either nitrosation or oxidation chemistry may predominate. The fundamental understanding between O2- and NO may provide new insight in the mechanisms responsible for inflammation-induced mutagenesis.

DNA Damage↗
PubMed1997

The content of intracellular mitochondrial DNA is decreased by 1-methyl-4-phenylpyridinium ion (MPP+).

1-Methyl-4-phenylpyridinium ion (MPP+), an oxidative metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), is considered to be directly responsible for MPTP-induced Parkinson's disease-like symptoms by inhibiting NADH-ubiquinone oxidoreductase (complex I) in the mitochondrial respiratory chain. Here we demonstrate that 25 microM MPP+ decreases the content of mitochondrial DNA to about one-third in HeLa S3 cells. On the contrary, 0.1 microM rotenone, which inhibits complex I to the same extent as 25 microM MPP+ in the cells, increases the content of mitochondrial DNA about 2-fold. Hence, the effect of MPP+ on mitochondrial DNA is not mediated by the inhibition of complex I. To examine the replication state of mitochondrial DNA, we measured the amount of nascent strands of mitochondrial DNA. The amount is decreased by MPP+ but increased by rotenone, suggesting that the replication of mitochondrial DNA is inhibited by MPP+. Because the proper amount of mitochondrial DNA is essential to maintain components of the respiratory chain, the decrease of mitochondrial DNA may play a role in the progression of MPTP-induced Parkinson's disease-like symptoms caused by the mitochondrial respiratory failure.

1-Methyl-4-phenylpyridinium↗
PubMed1997

A dual effect of 1-methyl-4-phenylpyridinium (MPP+)-analogs on the respiratory chain of bovine heart mitochondria.

We examined effects of several compounds, structurally related to 1-methyl-4-phenylpyridinium (MPP+), on the NADH-dependent respiration of bovine heart submitochondrial particles. 1-Methyl-4-(3 '-trimethylammoniophenyl)pyridinium (analog 8) as well as MPP+ completely inhibited O2 consumption, reduction of ubiquinone-10, and reduction of cytochrome b in a dose-dependent manner. The production of superoxide (O2-) induced by MPP+ or analog 8 was to the same extent as that by rotenone, an inhibitor of complex I of the mitochondrial respiratory chain. Rotenone had no additive effect on the maximal production of O2- induced by MPP+ or analog 8, suggesting that the production was mediated by the same way as rotenone. 1-Methyl-4-(4'-nitrophenyl) pyridinium (analog 1) induced about 20-fold more production of O2 than MPP+ and the production was additively increased by rotenone. Analog 1 only partially inhibited rotenone-sensitive O2 consumption. Paraquat induced the production of O2- as much as analog 1. Paraquat, however, did not inhibit rotenone-sensitive O2 consumption or reduction of cytochrome b. These results suggest that MPP+ and its analogs interact with the mitochondrial respiratory chain at two sites, the substrate side of the rotenone-binding site and the rotenone-binding site. The analogs may be reduced to produce O2- at the former site and inhibit the respiratory chain at the latter site.

Animals↗
PubMed1997

Changes of energy metabolism induced by 1-methyl-4-phenylpyridinium (MPP+)-related compounds in rat pheochromocytoma PC12 cells.

We examined effects of three structurally related pyridinium compounds, 1-methyl-4-phenylpyridinium (MPP+), paraquat, and 1-methyl-4-(4'-nitrophenyl) pyridinium (analog 1), on the energy metabolism in pheochromocytoma PC12 cells. MPP+ inhibited the intracellular NADH oxidation by the mitochondrial respiratory chain, judging from the decrease of the cytosolic NAD+/NADH ratio. Paraquat enhanced the oxidation of NADH and decreased intracellular ATP more than MPP+. The inhibition of the mitochondrial respiration by MPP+ was partially compensated by enhanced glycolysis, while paraquat inhibited glycolysis at the level of hexokinase probably due to the intracellular production of oxygen radicals. Analog 1 moderately enhanced glycolysis, moderately increased a cytosolic ratio of NAD+/NADH, and caused only a slight decline of intracellular ATP. Paraquat was the most cytotoxic of the three compounds. Thus, the three structurally related compounds, MPP+, paraquat, and analog 1, showed different effects on the mitochondrial respiratory chain and the glycolytic pathway in PC 12 cells. Their properties found in the cells well reflected those obtained by using bovine heart submitochondrial particles.

Adenosine Triphosphate↗
PubMed1997

Genetic evidence for the involvement of tau in progressive supranuclear palsy.

A dinucleotide repeat polymorphism in a tau intron was identified and used in a case-control study to analyze the genetic association of tau with several neurodegenerative diseases with tau pathology. Subjects with the homozygous tau AO alleles were excessively represented in the progressive supranuclear palsy (PSP) group, compared with the age-matched healthy control group. Consequently, this allele is more frequently found in PSP than in a group of healthy subjects. This trend was not found in Alzheimer's disease or parkinsonism-dementia complex of Guam, both of which are accompanied by major tau pathology. The result suggests a possible involvement of tau in the pathogenesis of PSP.

Base Sequence↗
PubMed1997

Coplanar PCBs and the relative contribution of coplanar PCBs, PCDDs, and PCDFs to the total 2,3,7,8-TCDD toxicity equivalents in human serum.

Coplanar PCBs in human serum were measured by high-resolution gas chromatography/isotope-dilution high-resolution mess spectrometry in 46 pulp and paper mill workers and 16 community residents with no specific known source of PCB exposure. The relative contribution of coplanar PCBs, PCDDs, and PCDFs to the total 2,3,7,8-TCDD toxicity equivalents (TEQs) were compared using the toxic equivalency factors proposed by Safe [1] and the factors recently proposed by WHO [2]. The mean concentrations of PCB-126 and PCB-169 were higher in paper mill workers than in community residents. However, these differences were not statistically significant. Serum PCB-126, but not PCB-169, was correlated with body mass index (Spearman's r = 0.40, p = 0.002). Serum PCB-169, but not PCB-126, was correlated with age (Spearman's r = 0.54, p = 0.0001). Multiple linear regression analysis for log-transformed combined PCBs showed that age (p = 0.008), body mass index (p = 0.031), and eating locally caught fish (p = 0.019) were statistically significant predictors. The majority of the total TEQ in serum is due to PCDDs (63%), whereas PCDFs account for 21% and coplanar PCBs account for 15% when calculated using the TEFs proposed by Safe. The percent contributions from PCDDs, PCDFs, and coplanar PCBs were 66%, 24%, and 10% respectively when calculated based on the TEFs proposed by WHO. Age, body mass index, and consumption of locally caught fish are significant predictors for coplanar PCB levels in human serum. Serum PCDDs were the major contributors to the total 2,3,7,8-TCDD equivalent toxicity in this study.

Benzofurans↗
PubMed1997

Proteolytic cleavage sites of band 3 protein in alkali-treated membranes: fidelity of hydropathy prediction for band 3 protein.

To assess the fidelity of hydropathy prediction for band 3 protein, we determined the cleavage sites of the protein and the portions of the protein tightly bound to the membrane lipid bilayer by means of in situ proteolytic digestion. For the removal of all anticipated hydrophilic connector loops from membranes, we had to denature the band 3 protein molecule in situ by alkali treatment. When the alkali-treated membranes were digested with trypsin, chymotrypsin, and pepsin, the majority of the anticipated transmembrane portions remained in the membrane fraction. However, five anticipated transmembrane portions were released into the supernatant fraction. Thus, the first, second, third, sixth and tenth anticipated transmembrane portions, in accordance with the hydropathy prediction, were released into the supernatant with the proteolytic digestion method. This indicates that these anticipated transmembrane portions are not bound with the boundary lipids although the hydrophobicity of these portions is comparable to that of the portions experimentally remaining in the membrane fraction. It is conceivable that the membrane peptide portions of band 3 protein could be classified into at least two categories, i.e. one bound to the boundary lipids and the other free from the boundary lipids. Approximately 90% of the transmembrane domain of the band 3 protein are recovered in either the supernatant fraction or the membrane fraction. The fidelity of hydropathy prediction for polytopic membrane proteins and the nature of the membrane embedded peptide portions are discussed.

Amino Acid Sequence↗
PubMed1997

Glial cells in Alzheimer's disease: preferential effect of APOE risk on scattered microglia.

Reactive glial cells are consistently found in the brain tissue of Alzheimer's disease (AD) patients. Both clustered and scattered glial cells occur in AD brain. A number of clustered microglial cells, but not astrocytes, had a positive correlation with neurite plaque numbers, suggesting that clustered micro-glial cells are uniquely associated with plaques whereas clustered astrocytes may have functions outside the plaques as well. APOE epsilon 4, the major genetic risk factor for AD, had a dose-dependent effect to increase the numbers of scattered microglial cells whereas the APOE risk showed no correlation with any of the clustered glial cells or scattered astrocytes. These findings raise the possibility that the increased levels of scattered, but not clustered, microglial cells are the immediate response to APOE risk and might be primarily involved in AD pathogenesis.

Aged↗
PubMed1997

Risk factors associated with uterine cervical cancer in Korea: a case-control study with special reference to sexual behavior.

OBJECTIVE: A hospital-based case-control study was conducted to identify characteristics of women at high risk of developing cervical cancer with special reference to sexual behavior in Korea. METHODS: Histologically confirmed cases of invasive cervical cancer were selected from the Department of Gynecology, Seoul National University Hospital between September 1992 to May 1995 (n = 203). Women with normal pap smear tests and women free of past history of any malignancies were regarded as controls (n = 827). Information on risk factors were collected by both a self-administered questionnaire and a direct interview. RESULTS: Uterine cervical cancer risk was higher in women with a less educated spouse (Ptrend = 0.0003), women with a family history of cervical cancer (adjusted odds ratio [OR] = 2.20., 95% confidence interval [CI] 1.21-4.01), women of shorter height (Ptrend = 0.02), women with early age at first full term pregnancy (Ptrend = 0.0005), and women who have had multiple full term pregnancies (Ptrend = 0.006) by the multiple linear logistic analysis. Particularly noteworthy was a significant decreasing trend in the adjusted OR with the age at first sexual intercourse increasing (Ptrend = 0.002) after adjusting the number of sexual partners. The husband's indecent sexual history showed a borderline significance (Ptrend = 0.07). CONCLUSIONS: This study confirmed that the risk factors of cervical cancer in Korea are similar with those found in other countries.

Adult↗