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Biomedical subjects

H N Kim

Publications and source records attributed to H N Kim.

At least 19 recordsLinked to original sources
PubMed1999

Effects of mineral fibers on the gene expression of proinflammatory cytokines and inducible nitric-oxide synthase in alveolar macrophages.

To determine which parameters are useful for the risk assessment of man-made mineral fibers (MMMFs), we examined the gene expression of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6) and inducible nitric-oxide synthase (iNOS) in mineral fiber-exposed alveolar macrophages (AMs). Male Wistar rats were intratracheally exposed to saline or mineral fibers suspended in saline (2 mg of crocidolite, chrysotile, alumina silicate refractory fiber (RF1) or potassium octatitanate whisker (TW)). Bronchoalveolar lavage was performed 4 weeks after the fiber-instillation, and the recovered AMs were stimulated by lipopolysaccharide for 2 or 6 hours. Expression of IL-1 alpha, TNF alpha, IL-6 and iNOS from AMs was observed using reverse transcription-polymerase chain reaction (RT-PCR). The levels of IL-1 alpha and IL-6 mRNA induced by mineral fiber exposure were greatest in AMs exposed to TW, crocidolite, chrysotile and RF1 in that order. However, both gene expression of iNOS and TNF alpha were not elevated in both crocidolite and TW exposure, despite their high pathological potential. These data suggested that IL-1 alpha and IL-6 may be useful indicators for the risk assessment of MMMFs.

Administration, Inhalation↗
PubMed1999

Noise level of drilling instruments during mastoidectomy.

Exposure to intense noise has been identified as a potential risk in the development of hearing impairment. Social concern about excessive noise is increasing and this also extends to the operating room. A noise level study was performed in the operating room during mastoidectomy with a sound level meter and it was analyzed by a sound-analyzing program. The drilling instruments used included the Stryker, Midas, M.P.S. and Med-Next. The operator was exposed to sound levels from 69 to 83 dBA. The loudest drilling instrument was the Midas and it produced an average sound level of 83 dBA to the operator. The mean exposure time was 41 minutes during mastoidectomy. This is below the occupational noise-level regulations in Korea. However, considering that individual susceptibility to noise varies and that the otologic surgeon is repeatedly exposed to prolonged drilling noise, ear protection is recommended for the operators of high-speed drilling instruments.

Chronic Disease↗
PubMed1998

Cloning and expression of cDNA for a human Sia alpha 2,3Gal beta 1, 4GlcNA:alpha 2,8-sialyltransferase (hST8Sia III).

The cDNA encoding human Sia-alpha2,3-Gal-beta1,4-GlcNAc-R:alpha2, 8-sialyltransferase, hST8Sia III, was isolated by screening of a human brain cDNA library with polymerase chain reaction-amplified DNA probe generated from the sequence of mouse ST8Sia III (mST8Sia III) and by 5' rapid amplification of cDNA ends of mRNA isolated from human brain tissues. Comparative analysis of the predicted protein-coding region between our cloned hST8Sia III and mST8Sia III showed 92 and 96% identities in the nucleotide and the amino acid sequence, respectively. The soluble hST8Sia III protein expressed in COS-7 showed an extremely high catalytic activity of transferring sialic acid through alpha2,8-linkage to intact fetuin glycoprotein, whereas the transferring activity was completely undetectable toward either alpha2,6-sialylated glycoprotein or desialylated glycoprotein acceptors. Northern analysis of hST8Sia III showed that the transcript corresponding to 11 kb was expressed in both human fetal and adult brain, while the expression of the 5.5-kb transcript was restricted to fetal liver, indicating that the expression of hST8Sia III is developmentally and tissue-specifically regulated.

Amino Acid Sequence↗
PubMed1998

Association of benign prostatic hyperplasia with male pattern baldness.

OBJECTIVES: Both benign prostatic hyperplasia (BPH) and male pattern baldness (androgenic alopecia) share the pathogenesis of an androgen-dependent disorder and afflict a large population of elderly men with chronobiologic progress. However, it is unclear whether these diseases are related epidemiologically. We evaluated the association of frequency and severity of male pattern baldness between patients with BPH and a control group. METHODS: A total of 225 patients with BPH (mean age 69.3 +/- 6.5 years) and 1 60 controls (mean age 68.5 +/- 6.4 years), all over 60 years of age, were included in this study. The estimation of baldness severity was based on Norwood's classification (grade I to VII). The International Prostate Symptom Score (IPSS) and genetic tendency for baldness were also evaluated. The difference between IPSS and grade of baldness between the two groups was analyzed by the Mann-Whitney test and the frequency of inherited baldness was compared by the chi-square test. Correlation between severity of baldness and IPSS in each group was estimated by Spearman's rank correlation method. RESULTS: The patients with BPH had an apparently higher grade of male pattern baldness in comparison with that of controls (median value of grade IV versus III, P <0.001). The proportion of men with male pattern baldness of grade IV or higher in the BPH group was significantly larger than that of controls (53.8% versus 36.9%, P <0.01). There was a greater frequency of inherited baldness in the BPH group than in the controls (31.6% versus 12.5%, P <0.001). No significant correlation was noted between baldness severity and IPSS in either group. CONCLUSIONS: This study demonstrates a strong association of BPH with male pattern baldness.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1998

What hysterectomy [corrected] patients want to know about the roles of residents and medical students in their care.

PURPOSE: To determine what patients want to know regarding the participation of trainees in their care. METHOD: In 1995, questionnaires were sent to 111 women who had undergone elective hysterectomies between September 1992 and June 1994 at two teaching hospitals at the University of California, San Francisco, School of Medicine. The questionnaires asked the women about their awareness of and attitudes toward the participation of residents and medical students in their care and about how they thought physicians should communicate information regarding residents to patients. RESULTS: Fifty-nine women (68%) returned the questionnaire. Thirty-seven of them (63%) knew that a resident had been involved in their care. Eighty percent of the respondents felt it important to know how residents were supervised and what they would do during the operation. Nearly half did not know whether a medical student had been involved in their care. Over 90% agreed that the attending gynecologist should tell patients that a resident would participate in the operation as well as what the resident would do. Most believed that residents are adequately supervised and that medical students have time to provide more attention to patients. CONCLUSIONS: Most of the women wanted to know about the participation and specific roles of residents and students. Attending physicians should take the initiative to talk with patients about the roles of trainees. Open discussions can promote patient autonomy, maintain public confidence in academic health institutions, and benefit future patients.

Attitude to Health↗
PubMed1997

A modified hearing aid fitting procedure using both real ear and 2cc coupler measurement system.

In order to reduce the test time in real ear hearing-aid fitting for children, the validity of applying the average real ear to coupler differences (RECDs) in prefitting procedure using a 2cc coupler measurement system was evaluated by checking whether the majority of people's RECDs might occur within 5 dB of the average RECDs (N = 116) in each test frequency and age group. The percentages of occurrence were around 90% in test subjects' RECDs in saturation sound pressure levels (SSPLs) and around 70% in gain in each important test frequency. Appropriate test frequencies in prefitting are 500, 1000, 1500 and 2000 Hz.

Adolescent↗
PubMed1996

Platelet activating factor and conception.

PURPOSE: This review provides evidence for the involvement of platelet activating factor (PAF) in the several facets of pregnancy establishment. METHODS: A comprehensive literature review and new data. RESULTS: PAF has a role in spermatozoal function, fertilization, embryo development, and implantation. CONCLUSIONS: PAF is intimately involved in conception.

Animals↗
PubMed1996

Establishment of primary cell culture from stria vascularis explants. Morphological and functional characterization.

To provide the prerequisite for long-term study of the inner ear related to structural and functional integrity, tissue of stria vascularis with spiral ligament was isolated from Wistar rat cochleas and cultured using the explant-culture technique. The following culture media were used: EMEM with Hepes buffer, hydrocortisone (400 ng/ml), transferrin (5 micrograms/ml). triiodothyronine (10(-9) M), cholera toxin (10(-10) M), insulin (5 micrograms/ml), and epidermal growth factor (10 ng/ml). To characterize the cells growing out from the explant, immunofluorescence with cytokeratin (cytokeratin 18) and ultrastructural examination with SEM and TEM were performed. The marginal cell function was investigated by expression of Na+, K(+)-ATPase antisera against beta 2 subunit of rat Na+, K(+)-ATPase and P-NPPase. We were able to maintain the cultured cells for 3 weeks or more. Monolayered marginal cells were observed beyond 14 days in vitro and the expression of cytokeratin 18 was especially enhanced. The cultured marginal cells were almost identical to in vivo cells both as regards ultrastructural features and Na+, K(+)-ATPase activity. The present results suggest that the primary explant culture technique is a reliable in vitro model of strial marginal cells. However, establishment of the cell line is needed for long-term study.

Animals↗
PubMed1995

Characterization of deletion and truncation mutants of the rat glucagon receptor. Seven transmembrane segments are necessary for receptor transport to the plasma membrane and glucagon binding.

Glucagon receptor mutants were characterized with the aim of elucidating minimal structural requirements for proper biosynthesis, ligand binding, and adenylyl cyclase coupling. One N-terminal deletion mutant and five truncation mutants with progressively shorter C termini were expressed in transiently transfected monkey kidney (COS-1) cells. Each truncation mutant was designed so that the truncated C-terminal tail would remain on the cytoplasmic surface of the receptor. In order to characterize the cellular location of the expressed receptor mutants, a highly specific, high affinity antipeptide antibody was prepared against the extracellular, N-terminal tail of the receptor. Immunoblot analysis and immunofluorescence microscopy showed that the presence of all seven putative transmembrane segments, but not not an intact N-terminal tail, was required for cell surface expression of the receptor. Membranes from cells expressing receptor mutants lacking a large portion of the N-terminal tail or any of the seven putative transmembrane segments failed to bind glucagon. Membranes from cells expressing the C-terminal tail truncation mutants, which retained all seven transmembrane segments, bound glucagon with affinities similar to that of the native receptor and activated cellular adenylyl cyclase in response to glucagon. These results indicate that all seven helices are necessary for the proper folding and processing of the glucagon receptor. Glycosylation is not required for the receptor to reach the cell surface, and it may not be required for ligand binding. However, the N-terminal extracellular portion of the receptor is required for ligand binding. Most of the distal C-terminal tail is not necessary for ligand binding, and the absence of the tail may increase slightly the receptor binding affinity for glucagon. The C-terminal tail is also not necessary for adenylyl cyclase coupling and therefore does not play a direct role in G protein (GS) activation by the glucagon receptor.

Amino Acid Sequence↗
PubMed1995

Up- and down-modulation of a cloned Aplysia K+ channel (AKv1.1a) by the activators of protein kinase C.

Modulation of a cloned Aplysia K+ channel, AKv1.1a, by protein kinase C (PKC) activators was examined in Xenopus oocytes expression system. Following the application of phorbol esters (phorbol 12-myristate 13-acetate, PMA; phorbol 12,13-dibutyrate, PDBu), or a diacylgrycerol analogue (1-oleoyl-2-acetyl-sn-glycerol, OAG), the fast inactivation of the AKv1.1a became slower and the peak current increased (up-modulation). However, the effect was transient. The expressed current was decreased even below control level about 15 to 20 min after the treatment (down-modulation). Both effects by PMA was blocked by the kinase inhibitor, H7, suggesting that phosphorylation by PKC is involved. The amino acid sequence of AKv1.1a contains three putative phosphorylation sites by PKC (Ser24, Thr345, Ser349). We tested their contributions to the PMA-induced modulation by site-directed mutagenesis. The results suggest that the up-modulation by PKC activators is due to the inhibition of the fast inactivation by the amino-terminal domain (N-type inactivation), thereby increase the time the channels are conductive. Phosphorylation of Ser24 may enhance the PKC-induced down-modulation, while phosphorylation of Thr345 may inhibit the down-modulation. By contrast, mutation of Ser349 did not affect the modulation. The N-type inactivation were not indispensable for the down-modulation because the amino-terminal deletion mutant also showed some down-modulation although its onset was quite slow. Thus, the down-modulation of AKv1.1a may be heterogeneous.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Redistribution of facial nerve motor neurons after recovery from nerve crushing injury in the gerbil.

We investigated the redistribution of facial motor neurons after recovery from a crush injury of the facial nerve in the mongolian gerbil, with the retrograde transportation of horseradish peroxidase (HRP) technique. The facial nerve at the vertical segment was crushed unilaterally for 10 s with forceps. After 1 month, movement of the vibrissae and blinking reflex were observed. Three months after nerve injury, we obtained the brainstems to investigate the distribution of the facial nerve motor neurons. On the normal side, motor neurons of the ophthalmic branch of the facial nerve were organized at the dorsomedial and dorsolateral subdivisions of the facial nucleus, and those of the superior buccal branch were distributed at intermediate and ventrolateral subdivisions of the facial nucleus in the brainstem. On the experimental side, instead of somatotopical organization, we found widespread irregular distribution of the motor neurons of both branches in the entire facial nucleus of the brainstem.

Animals↗
PubMed1995

Central projection of the peripheral cochlear nerve from each turn to the cochlear nuclei in the Mongolian gerbil.

The central projections of the peripheral cochlear nerve fiber from each turn to the cochlear nuclei (CN) in the mongolian gerbil were investigated using retrograde transportation of horseradish peroxidase (HRP). The organ of Corti and the osseous spiral lamina were scratched with an electrolytically-sharpened fine needle via a small hole at each turn of the cochlea. The cochlea was filled with a 30% horseradish peroxidase (HRP) solution. After 48 hours, 50 microns transverse serial sections of the brainstem were made with a vibratome. The tissue was processed with the diaminobenzidine procedure of the cobalt-glucose method. Our experiment revealed that the fibers from the basal turn terminated at the dorsomedial portion of anteroventral cochlear nuclei (AVCN), but those from the apical turn were distributed among the ventrolateral portion of the AVCN. In the posteroventral cochlear nuclei (PVCN) and dorsal cochlear nuclei (DCN), the fibers from basal to apical turns extend from the dorsal to the ventral portion of each nuclei. A distinct tonotopic arrangement could be found between the origin of cochlear fibers of each turn and their termination in the regions of the cochlear nuclei (CN). Also, the results suggested that the scratch method combined with retrograde transportation of horseradish peroxidase was useful in investigating the tonotopic arrangement of the peripheral auditory nerve in the CN.

Animals↗