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Biomedical subjects

G Kim

Publications and source records attributed to G Kim.

At least 19 recordsLinked to original sources
PubMed2006

Characteristics of CADASIL in Korea: a novel cysteine-sparing Notch3 mutation.

OBJECTIVE: To elucidate the phenotype, genotype, and MRI findings of Korean patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and mutation carriers. METHODS: The authors studied 40 members of nine unrelated Korean CADASIL families. After genetic analysis of Notch3, clinical and MRI findings were correlated in 27 mutation carriers. RESULT: Notch3 mutation sites were C174R (one family, n = 3), R133C (one family, n = 3), R587C (one family, n = 1), R544C (two families, n = 5), and R75P (four families, n = 15). The clinical features were typical of CADASIL, but the frequency of migraine in the Korean population appears low. MRI abnormalities were found in 54% of the mutant carriers, the most common being white matter hyperintensities. The prevalence of lacunes and microbleeds increased with patient age. Anterior temporal areas were less often involved in subjects with R75P mutations than in those where mutations occurred in other sites (p = 0.02). Gradient echo imaging identified microbleedings in 33% of mutation carriers (64% of those with abnormal MRI), whereas diffusion-weighted MRI showed abnormal findings in only one patient. Neurologic disability was related to the number of lacunar infarcts and the lesion volume of white matter hyperintensities (p < 0.001) whereas MMSE score was related to the number of lacunar infarcts (p < 0.005). CONCLUSIONS: Although Korean cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) mutation carriers show similar clinical and MRI findings, these abnormalities appear less frequently than in other populations. Relatively frequent microbleedings on gradient echo imaging suggest that treatment should be individualized according to MRI findings. The novel mutation of R75P, not involving a cysteine residue, is related to less frequent involvement of the anterior temporal area, thus broadening the spectrum of CADASIL.

Adult↗
PubMed2006

Enteroendocrine cell counts correlate with visceral hypersensitivity in patients with diarrhoea-predominant irritable bowel syndrome.

The objective of this study was to determine whether or not the number of enteroendocrine cells (ECs) in the gut is related to visceral hypersensitivity in patients with diarrhoea-predominant irritable bowel syndrome (D-IBS). Twenty-five subjects with D-IBS (mean, 43.1 years; 16 women, nine men) were recruited into our study, along with 13 healthy controls (mean, 40.7 years; nine women, four men). Maximally tolerable pressures were evaluated via barostat testing, and the levels of ECs were immunohistochemically identified and quantified via image analysis. The numbers of ECs between the D-IBS subjects and the controls were not significantly different in the terminal ileum, ascending colon and rectum. However, the maximally tolerable pressures determined in the D-IBS subjects were significantly lower than those of the control subjects (P < 0.01), and we detected a significant relationship between the maximally tolerable pressures and the numbers of ECs in the rectum (r = -0.37, P < 0.01). Rectal sensitivity was enhanced to a greater degree in D-IBS patients exhibiting an elevated level of rectal ECs. This study provides some evidence to suggest that ECs play an important role in visceral hypersensitivity.

Adult↗
PubMed2005

Formation, manipulation, and elasticity measurement of a nanometric column of water molecules.

Nanometer-sized columns of condensed water molecules are formed by an atomic-resolution force microscope operated in ambient conditions. An unusual stepwise decrease of the force gradient associated with the ultrathin water bridge in the tip-substrate gap is observed during its stretch, exhibiting regularity in step heights (approximately 0.5 N/m) and plateau lengths (approximately 1 nm). Such "quantized" elasticity is indicative of an atomic-scale stick slip at the tip-water interface. A thermodynamic-instability-induced rupture of the water meniscus (5 nm long and 2.6 nm wide) is also found. This work opens a high-resolution study of the structure and interface dynamics of a nanometric aqueous column.

Micromanipulation↗
PubMed2005

Spatial chemical inhomogeneity and local electronic structure of Mn-doped Ge ferromagnetic semiconductors.

We have investigated the chemical distributions and the local electronic structure of potential diluted magnetic semiconductor Ge0.94Mn0.06 single crystals using scanning photoelectron microscopy (SPEM), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The SPEM image shows the stripe-shaped microstructures, which arise from the chemical phase separation between the Mn-rich and Mn-depleted phases. The Mn 2p XAS shows that the Mn ions in the Mn-rich region are in the divalent high-spin Mn2+ states but that they do not form metallic Mn clusters. The Mn 3d PES spectrum exhibits a peak centered at approximately 4 eV below E(F) and the negligible spectral weight near E(F). This study suggests that the observed ferromagnetism in Ge1-xMnx arises from the phase-separated Mn-rich phase.

Journal Article↗
PubMed2005

Acculturation and manifestation of depressive symptoms among Korean-American older adults.

The present study examined the role of acculturation in manifestation of depressive symptoms among 230 Korean-American older adults (M age = 69.8, SD = 7.05) in Florida. Given the cultural emphasis on modesty and self-effacement in the traditional Korean society, we hypothesized that older Korean-Americans who were less acculturated to American culture, when compared to the more acculturated ones, would be more likely to inhibit positive affects in depressive symptom reports. Using two validated measures of depressive symptoms, the short forms of the Geriatric Depression Scale (GDS-SF) and the Center for Epidemiologic Studies-Depression Scale (CES-D), different response patterns for low and high acculturation groups were identified. First, there was low comparability in the factor structures for both the GDS-SF and the CES-D across low and high acculturation groups. A differential item function (DIF) analysis based on partial correlations indicated that older adults in the low acculturation group inhibited endorsing positive affect items; one item in the GDS-SF (#7 'feel happy') and two items in the CES-D (# 5 'felt hopeful' and # 8 'was happy'). The finding suggests the substantial cultural influences in expressing emotions, especially those related to positive affects. Implications are discussed from a cultural perspective.

Acculturation↗
PubMed2005

Renal clear-cell carcinoma: an ultrastructural study on the junctional complexes.

Junctional complexes such as tight junctions, adherens junctions, and desmosomes play crucial roles in the structure and function of epithelial cells. These junctions are involved in increasing cell-cell contact and as well serve as signaling centers regulating multiple functions in epithelial cells. Carcinoma cell lines cultured in the laboratory generally lack junctional complexes. However, studies directed towards understanding the distribution of junctional complexes in human cancer tissues are lacking. In this study, we analyzed by electron microscopy the distribution of junctional complexes in patients diagnosed with renal clear-cell carcinoma. We found that both tight junctions and adherens junctions were drastically reduced in patients with cancer compared to normal tissues. Desmosomes were not detected in normal proximal tubules while distinctly present in cancer tissues. These results suggest that analysis of junctional complexes in human tumors should provide valuable information that might have prognostic and diagnostic value.

Aged↗
PubMed2004

Temporal bone histopathology in dominantly inherited audiovestibular syndrome.

OBJECTIVE: To describe the clinical and pathologic features of a new dominantly inherited audiovestibular syndrome. METHODS: History, examination, and audiometric testing in the proband, brother, and son; quantitative rotational testing in the proband and son; histopathology of the cochlea and vestibular labyrinth in the proband; sequencing candidate genes COCH and MYO7A in the brother and son. RESULTS: Affected family members developed slowly progressive hearing loss beginning in their late 30s and progressive imbalance in their early 70s. Three of four affected had brief (minutes) episodes of vertigo typically occurring a few times per year. Auditory and vestibular function testing documented a slowly progressive loss of auditory and vestibular function. Postmortem examination showed a loss of hair cells in the cochlea and vestibular receptor organs. There were no cellular infiltrates or acidophilic deposits. No mutations were found in the COCH or MYO7A genes. CONCLUSIONS: This dominantly inherited audiovestibular syndrome results in a selective loss of hair cells in the auditory and vestibular end organs. Finding the causative gene could have important implications for understanding the pathophysiology of presbycusis and dysequilibrium of aging.

Adult↗
PubMed2004

Using the Diagnostic Assessment of the Severely Handicapped-II (DASH-II) to measure the therapeutic effects of risperidone.

BACKGROUND: Within the scope of a double-blind, placebo-controlled, crossover medication study, the Diagnostic Assessment of the Severely Handicapped-II (DASH-II) was evaluated as a measurement for determining the effectiveness of the medication risperidone in treating the problem behaviour of 21 people with intellectual disabilities (ID). METHOD: Participants' caregivers completed the DASH-II during the placebo/baseline phase of the study and the maintenance phase of the study, and completed the Aberrant Behavior Checklist - Community (ABC-C) weekly throughout the entire study. The results obtained using the DASH-II were compared to those obtained using the ABC-C, an instrument shown to be well correlated with the DASH-II. RESULTS: Results suggest that while the DASH-II and the ABC-C were well correlated during the placebo/baseline phase of the current study, they were not well correlated at completion of the 6-month maintenance phase of the medication trial. CONCLUSION: The DASH-II, while appropriate for assisting in the diagnosis of psychopathology in people with ID, does not appear to monitor changes in problem behaviour as a result of risperidone use as well as the ABC-C. Differences in the frequency of problem behaviour that each measure evaluated and the applicability of using the DASH-II to measure medication effects on problem behaviour are discussed.

Antipsychotic Agents↗
PubMed2003

Biological properties of allogenic articular chondrocytes on the surface of bovine cartilage explants in vitro.

Bovine cartilage explants were co-cultured with or without allogenic chondrocytes for 4 weeks. The attachment of the applied chondrocytes to cartilage after labelling with fluorescence was assessed using a confocal laser microscope. Morphological changes and the production of extracellular matrix (ECM) of co-cultured chondrocytes on intact and damaged surfaces of cartilage were evaluated by histological and immunohistochemical methods. Co-cultured chondrocytes attached to and proliferated on the intact and damaged areas of cartilage, and a new layer was created there. The defects were also filled with ECM produced by the co-cultured chondrocytes. Glycosaminoglycans and collagen type II were detected in the newly formed ECM, and large numbers of rounded chondrocytes were observed at primitive lacunae in this matrix at 4 weeks of culture. The results suggest that chondrocytes have the ability to attach to, to proliferate on and to establish a new matrix on the intact and damaged surfaces of cartilage explants.

Animals↗
PubMed2002

Bandgap modulation of carbon nanotubes by encapsulated metallofullerenes.

Motivated by the technical and economic difficulties in further miniaturizing silicon-based transistors with the present fabrication technologies, there is a strong effort to develop alternative electronic devices, based, for example, on single molecules. Recently, carbon nanotubes have been successfully used for nanometre-sized devices such as diodes, transistors, and random access memory cells. Such nanotube devices are usually very long compared to silicon-based transistors. Here we report a method for dividing a semiconductor nanotube into multiple quantum dots with lengths of about 10nm by inserting Gd@C82 endohedral fullerenes. The spatial modulation of the nanotube electronic bandgap is observed with a low-temperature scanning tunnelling microscope. We find that a bandgap of approximately 0.5eV is narrowed down to approximately 0.1eV at sites where endohedral metallofullerenes are inserted. This change in bandgap can be explained by local elastic strain and charge transfer at metallofullerene sites. This technique for fabricating an array of quantum dots could be used for nano-electronics and nano-optoelectronics.

Journal Article↗
PubMed2002

Immunoreactivity of Hu proteins facilitates identification of myenteric neurones in guinea-pig small intestine.

Hu proteins, together with neurone-specific enolase (NSE), protein gene product 9.5 (PGP-9.5), microtubule-associated protein-2 (MAP-2) and tubulin beta III isoform, were evaluated immunohistochemically as neuronal markers in whole-mount preparations and cultures obtained from the myenteric plexus of guinea-pig small intestine. Anti-Hu immunostaining marked the ganglion cell somas and nuclei without staining of the neuronal processes in the whole-mounts and cultures. The ganglion cell bodies were not obscured by staining of multiple neuronal fibres and this facilitated accurate counting of the neurones. MAP2 immunostaining also provided clear images of individual neurones in both whole mounts and cultures. Immunoreactivity for NSE, PGP-9.5 and tubulin beta III isoform provided sharp images of the ganglion cells in culture, but not in whole-mount preparations. Strong staining of the neuronal processes in the whole-mount preparations obscured the profiles of the ganglion cell bodies to such an extent that accurate counting of the total neuronal population was compromised. Anti-Hu immunostaining was judged to be an acceptable method for obtaining reliable estimates of total numbers of myenteric neurones in relation to other specific histochemical properties such as histamine binding.

Animals↗
PubMed2002

A study of methods to reduce groundwater contamination around the Kimpo landfill in Korea.

Four different methods were studied to reduce the groundwater contamination around the Kimpo landfill in Korea by leakage of a leachate. The hydraulic parameters were measured for this study and then the groundwater flow and contaminant transport systems around the Kimpo landfill were simulated with MODFLOW and MT3D models. Both the method of establishing 5 sets of Radial Collector Well Laterals (RCWLs) within the landfill and a method utilizing the wells for dewatering condensed water brought about a 70% leachate elimination efficiency. Their construction costs were cheap, and the maximum concentrations of chloride and phenol in the leachate effluent were high. Meanwhile, a method establishing an interception wall to the 2nd layer at the cirumference of the landfill and 22 sets of RCWLs within it brought about a 92% leachate elimination efficiency. Its construction cost was expensive, and the maximum concentrations of chloride and phenol in the leachate effluent were low. A method of establishing an interception wall to the 3rd layer and 40 sets of RCWLs brought about a 97% leachate elimination efficiency. Its construction cost was the most expensive, and the maximum concentrations of chloride and phenol were low. Conclusively, a method of establishing 22 sets of RCWLs was evaluated as the most stable and economical option to reduce groundwater contamination concentration below drinking water standard.

Cost-Benefit Analysis↗
PubMed2001

Measurement of 224Ra and 225Ra activities in natural waters using a radon-in-air monitor.

We report a simple new technique for measuring low-level radium isotopes (224Ra and 226Ra) in natural waters. The radium present in natural waters is first preconcentrated onto MnO2-coated acrylic fiber (Mn fiber) in a column mode. The radon produced from the adsorbed radium is then circulated through a closed air-loop connected to a commercial radon-in-air monitor. The monitor counts alpha decays of radon daughters (polonium isotopes) which are electrostatically collected onto a silicon semiconductor detector. Count data are collected in energy-specific windows, which eliminate interference and maintain very low backgrounds. Radium-224 is measured immediately after sampling via 220Rn (216Po), and 226Ra is measured via 222Rn 218Po) after a few days of ingrowth of 222Rn. This technique is rapid, simple, and accurate for measurements of low-level 224Ra and 226Ra activities without requiring any wet chemistry. Rapid measurements of short-lived 222Rn and 224Ra, along with long-lived 226Ra, may thus be made in natural waters using a single portable system for environmental monitoring of radioactivity as well as tracing of various geochemical and geophysical processes. The technique could be especially useful for the on-site rapid determination of 224Ra which has recently been found to occur at elevated activities in some groundwater wells.

Environmental Monitoring↗
PubMed2001

Loss-of-function EA2 mutations are associated with impaired neuromuscular transmission.

OBJECTIVE: To examine the functional consequences of episodic ataxia type 2 (EA2)-causing nonsense and missense mutations in vitro and to characterize the basis of fluctuating weakness in patients with E2A. BACKGROUND: Mutations in CACNA1A encoding the Ca(v)2.1 calcium channel subunit cause EA2 through incompletely understood mechanisms. Although the Ca(v)2.1 subunit is important for neurotransmission at the neuromuscular junction, weakness has not been considered a feature of EA2. METHODS: The disease-causing mutations in three unrelated patients with EA2 and fluctuating weakness were identified by mutation screening and sequencing. Mutant constructs harboring mutations R1281X, F1406C, R1549X were transfected into COS7 cells and expressed for patch clamp studies. Single-fiber electromyography (SFEMG) was performed in patients to examine synaptic transmission at the neuromuscular junction. RESULTS: Functional studies in COS7 cells of nonsense and missense EA2 mutants demonstrated markedly decreased current densities compared with wild type. SFEMG demonstrated jitter and blocking in these patients with EA2, compared with normal subjects and three patients with SCA-6. CONCLUSION: EA2-causing missense and nonsense mutations in CACNA1A produced mutant channels with diminished whole cell calcium channel activity in vitro due to loss of function. Altered biophysical properties or reduced efficiency of plasma membrane targeting of mutant channels may contribute to abnormal neuromuscular transmission, manifesting as myasthenic syndrome.

Calcium Channels↗
PubMed2001

Reduction of human prostate tumor vascularity by the alpha1-adrenoceptor antagonist terazosin.

BACKGROUND: We previously demonstrated that the quinazoline-derived a1-adrenoceptor antagonists doxazosin and terazosin suppress prostate cancer growth via apoptosis induction. The aim of this study was to determine the potential effect of a1-adrenoceptor antagonists on tumor vascularity of the human prostate. METHODS: A total of 34 men with benign prostatic hyperplasia (BPH) who have been on terazosin treatment (for the obstructive symptoms) were pathologically diagnosed with prostate cancer following surgery. These patients were stratified according to the length of treatment periods with terazosin into two groups, 1 week-6 months, and 6-17 months. The control group consisted of prostatectomy specimens from 25 untreated prostate cancer patients undergoing surgery for localized disease. Formalin-fixed, paraffin-embedded prostate specimens were analyzed for apoptosis (TUNEL assay), cell proliferation (Ki-67), microvessel density (MVD) (von Willebrand factor/Factor VIII), vascular endothelial growth factor (VEGF) expression, and prostate specific antigen (PSA) immunoreactivity. RESULTS: A significant induction of apoptosis was observed among cancerous prostatic epithelial cells in the terazosin-treated, as compared to the untreated prostate cancer specimens, while there was no significant change in the proliferative index of the same tumor cell populations after treatment. Furthermore, terazosin resulted in a significant decrease in prostate tissue MVD compared with the untreated group (P < 0.01), that correlated with the increased apoptotic index of the cancerous areas. Tissue PSA expression in the prostatic tumor foci was also markedly reduced after terazosin treatment, while no significant changes in VEGF expression were detected. CONCLUSIONS: These findings provide the first evidence that terazosin, a quinazoline-based a1-blocker decreases prostate tumor vascularity. Our study has significant clinical implications in identifying selected alpha1-adrenoceptor antagonists as potential anti-tumor agents with apoptotic and anti-angiogenic effects in the human prostate that can be exploited for the treatment of advanced prostate cancer.

Adrenergic alpha-Antagonists↗