Drug abuse trends and epidemiological aspects of drug associated deaths in Korea.
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Adolescent↗
Biomedical subjects
H Chung
Publications and source records attributed to H Chung.
Evaluation of the antioxidant potential of natural products.
Since reactive oxygen radicals play an important role in carcinogenesis and other human disease states, antioxidants present in consumable fruits, vegetables, and beverages have received considerable attention as cancer chemopreventive agents. Thus, in order to identify antioxidants in plant extracts, test materials were assessed for potential to scavenge stable 1,2-diphenyl-2-picrylhydrazyl (DPPH) free radicals, reduce TPA-induced free radical formation in cultured HL-60 human leukemia cells, and inhibit responses observed with a xanthine/xanthine oxidase assay system. Approximately 700 plant extracts were evaluated, and 28 were found to be active in the DPPH free radical scavenging assay. Based on secondary analyses performed to assess inhibition of 7,12-dimethylbenz(a)anthracene-induced preneoplastic lesion formation with a mouse mammary organ culture model, Chorizanthe diffusa Benth. (Polygonaceae), Mezoneuron cucullatum Roxb. (Leguminosae), Cerbera manghas L. (Apocynaceae) and Daphniphyllum calycinum Benth. (Daphniphyllaceae) were selected and subjected to bioassay-guided fractionation. 5,7,3',5'-Tetrahydroxy-8,4'-dimethoxyflavonol, 5,8,4'-trihydroxy-7,3'-dimethoxyflavonol, 5,3',4'-trihydroxy-7-methoxyflavonol, and 6,3',4'-trihydroxy-7-methoxyflavonol were identified as active principles from C. diffusa. Piceatannol, trans-resveratrol, apigenin and scirpusin A were found as the active principles of M. cucullatum, olivil, (-)-carinol, and (+)-cycloolivil were active principles from C. manghas, and 5,6,7,4'-tetrahydroxyflavone 3-O-rutinoside and kaempferol 3-O-neohesperidoside were active principles from D. calycinum. Of these substances, the hydroxystilbenes piceatannol and transresveratrol have thus far been shown to inhibit carcinogen-induced preneoplastic lesion formation in the mouse mammary gland organ culture model.
Animals↗
Phantoms for noninvasive blood glucose sensing with near infrared transmission spectroscopy.
In vivo spectra from human subjects can be simulated with a phantom composed of different layers of water, fat and muscle tissue. All three components are necessary to simulate in vivo spectra collected over the combination spectral region (5000-4000 cm-1). Muscle tissue is not required, however, to accurately simulate overtone spectra (6600-5400 cm-1). The near-IR spectral characteristics of fat and muscle tissue from several animal sources are essentially identical to those found for human tissue, hence, the animal source for these phantom components is not critical. Thickness of each tissue layer can be determined by a regression analysis where the in vivo spectrum of interest is regressed against standard absorbance spectra of the necessary model components (water, fat and muscle). In general, in vivo overtone spectra collected across human webbing tissue with a thickness of 6.7 mm can be simulated with water layer thicknesses ranging from 5.0 to 6.4 mm combined with fat layer thicknesses from 1.4 to 4.2 mm.
Animals↗
Slow degradation of aggregates of the Alzheimer's disease amyloid beta-protein by microglial cells.
Microglia are immune system cells associated with senile plaques containing beta-amyloid (Abeta) in Alzheimer's disease. Although microglia are an integral part of senile plaques, their role in the development of Alzheimer's disease is not known. Because microglia are phagocytic cells, it has been suggested that microglia may function as plaque-attacking scavenger cells. Microglia bind and internalize microaggregates of Abeta that resemble those present in dense Alzheimer's disease plaques. In this study, we compared the degradation by microglia of Abeta microaggregates with the degradation of two other proteins, acetylated low density lipoprotein and alpha2-macroglobulin. We found that the majority of the internalized Abeta in microaggregates was undegraded 72 h after uptake, whereas 70-80% of internalized acetylated low density lipoprotein or alpha2-macroglobulin was degraded and released from cells in trichloroacetic acid-soluble form after 4 h. In the continued presence of fluorescent Abeta microaggregates for 4 days, microglia took up huge amounts of Abeta and became engorged with undigested material. These data suggest that microglia can slowly degrade limited amounts of Abeta plaque material, but the degradation mechanisms can be overwhelmed by larger amounts of Abeta.
Alzheimer Disease↗
Cultural factors in the treatment of a catatonic Chinese patient.
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Adult↗
Preretinal neovascularization induced by experimental retinal vein occlusion in albino rats.
Retinal ischemia and neovascularization have been demonstrated in several animal models. To determine 1) whether the retinal or preretinal neovascularization can be induced in albino rats by retinal vein occlusion and 2) the type and rate of occurrence on neovascularization, we occluded retinal veins in albino rats by photodynamic thrombosis. After anesthesia, each of 36 rats received an injection of rose bengal photosensitive dye, and their veins underwent argon green laser treatment. Half or all the major retinal veins were occluded in 12 eyes and in 24 eyes, respectively. Ten control rats underwent the same procedures but the laser beam was directed between major retinal vessels. In 46 control eyes, rose bengal dye was seen to have perfused without laser treatment. Retinal detachment developed in most vein occluded eyes within one day of venous occlusion, which was confirmed by fluorescein angiography. On follow-up at two weeks, only four of 24 eyes (16.7%) had undergone occlusion of all retinal veins showed new preretinal vessels on the optic disc. In these four eyes, severe disturbance of both retinal arterial and venous blood flow was observed, but no other eyes showed such severe combined disturbance. These data suggest that preretinal neovascularization in albino rats can be induced by this minimally traumatic method and that venous occlusion is severe enough to compromise arterial blood flow for a certain threshold period, thus inducing the development of preretinal neovascularization.
Animals↗
Antiproliferative effect of mitomycin C on experimental proliferative vitreoretinopathy in rabbits.
To investigate the therapeutic potential of mitomycin C (MMC) in the management of proliferative vitreoretinopathy (PVR), antiproliferative effect of MMC on rabbit retinal pigment epithelial (RPE) cells, its intraocular toxicity, and its preventive effect on experimental PVR were investigated. Cultured rabbit RPE cells were exposed to various concentrations of MMC ranging from 1.0 x 10(-3) to 1.0 microgram/ml for 72 hours. The RPE cells were then cultured in a medium without MMC for another 7 days, and the cells were harvested and counted. Toxicity of MMC to rabbit retina was evaluated after intravitreal injection of MMC by means of clinical observation, electrophysiologic test, and histopathologic examination. To test antiproliferative effect of MMC on experimental PVR, 200,000 cultured RPE cells were injected into the vitreous cavity of pigmented rabbits, and either 0.2 micrograms or 1.0 micrograms MMC was injected intravitreally 24 hours after RPE cell injection. Two to four weeks later, the vitreoretinal status was compared between MMC-treated eyes and control eyes. The antiproliferative effect of MMC on RPE cells was evident at the concentration of 1.0 x 10(-2) micrograms/ml. The drug concentration required for 50% inhibition of growth was 3 x 10(-2) micrograms/ml. Nontoxic intraocular doses of MMC were 2.0 micrograms in rabbit eyes with normal vitreous and 1.0 microgram in rabbit eyes with gas-compressed vitreous. The rates of traction retinal detachment after intravitreal RPE cell injection were reduced in the eyes treated with MMC compared with control eyes. These results indicate that MMC may have clinical application to the treatment of PVR.
Animals↗
Titanium shielding. An alternative method for guided tissue regeneration.
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Adolescent↗
Epidemiological, clinical, and neuropathological study of apolipoprotein E genotype in Alzheimer's disease.
Our studies of the APOE genotype in AD confirm a strong association of the epsilon 4 allele with development of AD and a decreased risk associated with epsilon 2. From a clinical/neuropathological perspective, the major effects of APOE epsilon 4 are to lower the age of onset and to increase the amount of A beta deposit in the brain. Neither rate of progression nor number of neurofibrillary tangles were affected. We also carried out a longitudinal population-based assessment of the APOE genotype to determine the risk for developing cognitive impairment of someone in the general population based on APOE genotype. APOE epsilon 4 carried about 1.4-fold increased risk, and APOE epsilon 2 about 1.7-fold decreased risk. Thus, inheritance of APOE epsilon 4 is a major biological risk factor for AD, but it has limited utility as a prognostic indicator for development of dementia in an individual.
Age of Onset↗
Near-infrared spectroscopic measurement of physiological glucose levels in variable matrices of protein and triglycerides.
Selective calibration models are generated for glucose over the 1-20 nM concentration range by use of partial least-squares regression analysis of near-infrared spectra from 5000 to 4000 cm-1. Two spectral data sets are used to simulate triglyceride and protein variations in clinical samples. Triacetin is used in one data set to simulate variations in triglyceride levels, and bovine serum albumin (BSA) is used in the second data set to simulate variations in blood protein levels. Although these matrix components possess strong absorption bands that overlap and overshadow the absorption bands of glucose, successful calibration models can be generated with no evidence of prediction bias caused by the different levels of the matrix components. Furthermore, the benefits of using digital Fourier filtering as a preprocessing step are evaluated in terms of calibration performance. The resulting calibration models provide standard errors of prediction of 0.5 and 0.2 mM in triacetin and BSA matrices, respectively. Accurate glucose predictions are demonstrated from spectra that correspond to protein concentrations not present in the calibration data set. Lastly, digital Fourier filtering alone is shown to have only limited ability to isolate glucose signals from those of BSA and triacetin due to similarities in the widths of the absorption bands of the three species.
Animals↗
Clinical and neuropathological correlates of apolipoprotein E genotype in Alzheimer's disease. Window on molecular epidemiology.
Inheritance of the apolipoprotein E (apo E) epsilon 4 allele has recently been found to be associated with Alzheimer's disease. We have studied the clinical and neuropathological correlates of apolipoprotein E genotype in a large group of Alzheimer's patients. The primary influence on clinical presentation is a shift towards earlier age of onset in individuals who have the apo E epsilon 4 gene: no change in clinical course was observed. In neuropathological studies, we find that the major influence of apo E epsilon 4 is on increased A beta deposition. These results led to a model of the biological interaction between the apo E protein and Alzheimer's disease.
Age of Onset↗
Lack of association of trinucleotide repeat polymorphisms in very-low-density lipoprotein receptor gene with Alzheimer's disease.
Inheritance of the apolipoprotein E epsilon 4 allele is a risk factor for Alzheimer's disease (AD). A recent report studying Japanese patients suggested that a polymorphism of a trinucleotide repeat in the 5' untranslated region of an apolipoprotein E receptor, the very-low-density lipoprotein receptor, is genetically associated with AD, with overrepresentation of the allele containing five copies of the repeat. We determined the allele frequencies of the very-low-density lipoprotein receptor in 3 white populations totaling 469 individuals. In contrast to the previous report, we found no differences in allele frequencies between case patients and control subjects. The discrepancy could be due to differences in Japanese and white populations. Nonetheless, these data weaken the likelihood that this polymorphism in the very-low-density lipoprotein receptor gene is strongly associated with AD.
Alleles↗
Apolipoprotein E and cognitive change in an elderly population.
The apolipoprotein E (apoE) epsilon 4 allele is overrepresented, and the apoE epsilon 2 allele underrepresented, in Alzheimer's disease. To assess the risk of cognitive impairment in individuals with these genotypes in the general population, we studied a population-based sample of 1,899 individuals 65 years and older as a follow-up to the Iowa 65+ Rural Health Study. Multiple regression and logistic regression analyses demonstrated significant effects of apoE epsilon 4 and apoE epsilon 2 in predicting performance on a delayed recall task over a 4- to 7-year period. The magnitude of this effect was, however, fairly modest, with odds ratios for developing impairment of approximately 1.37 (95% confidence interval: 1.007, 1.850; p = 0.045) for apoE epsilon 4 and 0.53 (95% confidence interval: 0.368, 0.777; p = 0.001) for apoE epsilon 2. These effects were more pronounced in women than men. Importantly, 85% of elderly apoE E4/4 individuals (average age, 81) scored in the unimpaired range on a screening mental status test. Thus, many individuals reach old age without cognitive impair- ment despite inheritance of one or two apoE epsilon 4 alleles. This suggests that apoE genotyping will have limited utility as a diagnostic or prognostic indicator of cognitive decline in individuals.
Aged↗
Patterns of adolescent involvement in problem behaviors: relationship to self-efficacy, social competence, and life events.
Using a sample of 556 adolescents from a suburban community, patterns of various adolescent problem behaviors (e.g., delinquent behavior, smoking, use of alcohol or drugs) and their links to self-efficacy, social competence, and life events were examined. Cluster analysis was conducted to identify four subgroups of adolescents who showed distinct patterns of problem behaviors. These clusters were compared on the measures of self-efficacy, social competence, and life events. Overall results suggest there are meaningful links between adolescents' problem behavior patterns and self-efficacy, the amount and quality of participation in various after school activities, and life events. For example, a subgroup of adolescents who showed uniformly low prevalence of all problem behaviors reported more positive academic self-efficacy, more active participation in sports and nonsports activities, more positive life events, and fewer negative events than adolescents who were involved in multiple problem behaviors. Implications for prevention and future research on adolescent problem behaviors are discussed.
Adolescent↗
Expression of the very low-density lipoprotein receptor (VLDL-r), an apolipoprotein-E receptor, in the central nervous system and in Alzheimer's disease.
The very low density lipoprotein receptor (VLDL-r) is a cell-surface molecule specialized for the internalization of multiple diverse ligands, including apolipoprotein E (apoE)-containing lipoprotein particles, via clathrin-coated pits. Its structure is similar to the low-density lipoprotein receptor (LDL-r), although the two have substantially different systemic distributions and regulatory pathways. The present work examines the distribution of VLDL-r in the central nervous system (CNS) and in relation to senile plaques in Alzheimer disease (AD). VLDL-r is present on resting and activated microglia, particularly those associated with senile plaques (SPs). VLDL-r immunoreactivity is also found in cortical neurons. Two exons of VLDL-r mRNA are differentially spliced in the mature receptor mRNA. One set of splice forms gives rise to receptors containing (or lacking) an extracellular O-linked glycosylation domain near the transmembrane portion of the molecule. The other set of splice forms appears to be brain-specific, and is responsible for the presence or absence of one of the cysteine-rich repeat regions in the binding region of the molecule. Ratios of the receptor variants generated from these splice forms do not differ substantially across different cortical areas or in AD. We hypothesize that VLDL-r might contribute to metabolism of apoE and apoE/A beta complexes in the brain. Further characterizations of apoE receptors in Alzheimer brain may help lay the groundwork for understanding the role of apoE in the CNS and in the pathophysiology of AD.
Aged↗
Detection of human enteric viruses in oysters by in vivo and in vitro amplification of nucleic acids.
This study describes the detection of enteroviruses and hepatitis A virus in 31 naturally contaminated oyster specimens by nucleic acid amplification and oligonucleotide probing. Viruses were extracted by adsorption-elution-precipitation from 50-g oyster samples harvested from an area receiving sewage effluent discharge. Ninety percent of each extract was inoculated into primate kidney cell cultures for virus isolation and infectivity assay. Viruses in the remaining 10% of oyster extract that was not inoculated into cell cultures were further purified and concentrated by a procedure involving Freon extraction, polyethylene glycol precipitation, and Pro-Cipitate precipitation. After 3 to 4 weeks of incubation, RNA was extracted from inoculated cultures that were negative for cytopathic effects (CPE). These RNA extracts and the RNA from virions purified and concentrated directly from oyster extracts were subjected to reverse transcriptase PCR (RT-PCR) with primer pairs for human enteroviruses and hepatitis A virus. The resulting amplicons were confirmed by internal oligonucleotide probe hybridization. For the portions of oyster sample extracts inoculated into cell cultures, 12 (39%) were positive for human enteroviruses by CPE and 6 (19%) were positive by RT-PCR and oligoprobing of RNA extracts from CPE-negative cell cultures. For the remaining sample portions tested by direct RT-PCR and oligoprobing after further concentration, five (about 16%) were confirmed to be positive for human enteroviruses. Hepatitis A virus was also detected in RNA extracts of two CPE-positive samples by RT-PCR and oligoprobing. Combining the data from all three methods, enteric viruses were detected in 18 of 31 (58%) samples. Detection by nucleic acid methods increased the number of positive samples by 50% over detection by CPE in cell culture. Hence, nucleic acid amplification methods increase the detection of noncytopathic human enteric viruses in oysters.
Animals↗
A newly identified polymorphism in the apolipoprotein E enhancer gene region is associated with Alzheimer's disease and strongly with the epsilon 4 allele.
Apolipoprotein E allele 4 (apoE epsilon 4) is a major risk factor for late-onset AD. Inheritance of this allele is associated with an earlier age of onset of dementia in individuals with AD. It is unknown whether other polymorphisms in the apoE gene may influence the effect of apoE epsilon 4 on AD. We screened portions of the promoter enhancer element and of the apoE receptor binding domain for other polymorphisms that could affect risk of AD. In particular, a C/G polymorphism at position +113 of the apoE mRNA in the apoE intron 1 enhancer element (IE1) has been recently identified. We found no other polymorphisms. We studied the relationship of the two alleles of the IE1 polymorphism with AD and found an apparent association between IE1 G and AD (n = 94; p = 0.0515). However, the IE1 G allele is also closely associated with apoE epsilon 4 (p < 0.0001). When the presence of apoE epsilon 4 is covaried, the association between the IE1 G allele and AD is no longer statistically significant (odds ratio = 1.29, 95% confidence interval: 0.44, 3.78). In contrast, epsilon 4 is still highly associated with AD when IE1 G is controlled for (odds ratio = 5.91, 95% confidence interval: 3.29, 10.63). Furthermore, there is no significant association between the age of onset of dementia and the inheritance of the G allele. We believe that the apparent association between IE1 G and AD is a consequence of the association between the epsilon 4 and IE1 G alleles.
Adult↗
Ethnocultural factors in the development of an Asian American psychiatrist.
Despite rising numbers of Asian American psychiatric trainees, little has been written about the specific problems arising in training for members of this ethnic minority group. The authors discuss some of the difficulties for the Asian American psychiatric trainee, in relation to the stigma of mental illness and its impact on the trainee's decision to enter psychiatry, ethnic identity and stereotyping, psychotherapy supervision, and career opportunities. Specific vignettes will describe each of these situations and the internal conflicts they engender during training. The resolution of these conflicts will be described within a transference and countransference framework with the intent of providing a starting point for process-oriented supervision geared toward the development of a professional identity. Specific recommendations will be given for the educational and career development process for Asian American psychiatric trainees.
Asian↗