Search PubMed⌕ Search

Biomedical subjects

H Kim

Publications and source records attributed to H Kim.

At least 541 records · Page 30Linked to original sources
PubMed1997

Differential functional significance of AP-1 binding sites in the promoter of the gene encoding mouse tissue inhibitor of metalloproteinases-3.

Tissue inhibitor of metalloproteinases-3 (TIMP-3) is an extracellular-matrix-associated protein that suppresses tumorigenicity or invasion in several model systems. We have identified, by in vitro footprinting, six AP-1 (activator protein-1) or AP-1-like binding sites in the mouse TIMP-3 promoter that bind purified c-Jun homodimers. Electrophoretic mobility shift assays revealed that the non-consensus fifth AP-1 binding site (AP-720; nt -720 to -714) had the strongest binding activity for recombinant c-Jun protein, and that the fourth binding site (AP-763; nt -763 to -754) and AP-720 showed strong binding activity for cellular nuclear proteins. Antibody supershift and blocking experiments suggest that AP-720, but not AP-763, binds authentic AP-1 components. Transient transfection reporter assays of deletion constructs showed that the region spanning AP-720 has the highest transcriptional activity, and that sequences 5' to this region (nt -2846 to -747) may contain negative regulatory elements. The deletion construct containing about 500 nt 5' to the transcriptional start, but no AP-1 sites, showed lower but significant activity, suggesting both AP-1-dependent and -independent regulation of the mouse TIMP-3 promoter. Mutational inactivation of AP-720 abolished the activity increment that distinguished the reporter construct containing both AP-720 and sixth AP-1 binding site (AP-617; nt -617 to -611) from that containing only AP-617. In summary, we report here that both AP-1 and non-AP-1 elements contribute to activity, with the non-consensus AP-1 site at -720 showing the greatest functional significance among the AP-1 sites.

3T3 Cells↗
PubMed1997

Chromosomal localization and neural distribution of voltage dependent calcium channel beta 3 subunit gene.

Voltage dependent calcium channel (VDCC) mediates the influx of free calcium ions that acts as a signal transducer. The beta 3 subunit of the VDCC regulates the activation (opening) and inactivation (closing) kinetics through phosphorylation/dephosphorylation. We isolated a genomic clone of the human VDCC beta 3 subunit from a human genomic DNA library using VDCC beta 3 cDNA as a probe. We localized VDCC beta 3 with this genomic DNA on the chromosome by fluorescent in situ hybridization, and the distribution of VDCC beta 3 in the nervous system was investigated in rats by in situ hybridization histochemistry with rat VDCC beta 3 cDNA. The gene for the VDCC beta 3 was specifically localized on human chromosome 12q13. The mRNA for the VDCC beta 3 was predominantly expressed in the nervous system. In the brain, a strong expression of VDCC beta 3 mRNA was found in the medial habenular nucleus, a high level of expression was observed in the olfactory bulb and cerebellum, and a relatively high level of VDCC beta 3 mRNA was localized in the cerebral cortex, caudate-putamen and hippocampal formation. Interestingly, this distribution pattern is very similar to that of the rbE-II, mid-low VDCC 1 subunit, and it is suspected that VDCC beta 3 and rbE-II may function together as a pair.

Animals↗
PubMed1997

Photoaffinity labelling of human poly(ADP-ribose) polymerase catalytic domain.

Photoaffinity labelling of the human poly(ADP-ribose) polymerase (PARP) catalytic domain (40 kDa) with the NAD+ photoaffinity analogue 2-azido-[alpha-32P]NAD+ has been used to identify NAD+-binding residues. In the presence of UV, photo-insertion of the analogue was observed with a stoichiometry of 0.73 mol of 2-azido-[alpha-32P]NAD+ per mol of catalytic domain. Competition experiments indicated that 3-aminobenzamide strongly protected the insertion site. Residues binding the adenine ring of NAD+ were identified by trypsin digestion and boronate affinity chromatography in combination with reverse-phase HPLC. Two major NAD+-binding residues, Trp1014 of peptide Thr1011-Trp1014 and Lys893 of peptide Ile979-Lys893, were identified. The site-directed mutagenesis of these two residues revealed that Lys893, but not Trp1014, is critical for activity. The close positioning of Lys893 near the adenine ring of NAD+ has been confirmed by the recently solved crystallographic structure of the chicken PARP catalytic domain [Ruf, Menissier-de Murcia, de Murcia and Schulz (1996) Proc. Natl. Acad. Sci. U.S.A. 93, 7481-7485].

Affinity Labels↗
PubMed1997

Clonality of dysplastic epithelium in colorectal adenomas from familial adenomatous polyposis patients.

Loss of function of both alleles of the APC gene results in colorectal adenoma formation in familial adenomatous polyposis, an autosomal dominant genetic disorder leading to multiple colorectal tumors at an early age. Previous molecular studies indicate that the mutant cells forming dysplastic epithelium within adenomas are clonally derived. We show, using immunostaining and molecular techniques, that the dysplastic epithelium of adenomas actually contains a mixture of cells derived from both mutant and normal stem cells. Well-differentiated mucous cells in the dysplastic epithelium, one of the indicators of severity of dysplasia, were derived from normal stem cells. Carcinomas in these patients, in contrast, contained only mutant cells, indicating that the subsequent mutations incurred by these cells have led to their isolation from the normal population.

Adenoma↗
PubMed1997

Inhibition of monoamine oxidase A by beta-carboline derivatives.

beta-Carbolines are endogenous inhibitors of monoamine oxidase (MAO). The interaction of nine beta-carboline derivatives and four 3,4-dihydro forms with purified MAO A was investigated. All the compounds tested were reversible competitive inhibitors selective for MAO A, in agreement with previous studies on membrane preparations. The oxidation of kynuramine by MAO A in the presence of the more effective inhibitors showed a lag period before reaching the steady state. In general, the 1-methyl and 7-methoxy substituents increased the potency. Harmine, 2-methylharminium, 2,9-dimethylharminium, and harmaline were the most effective inhibitors of the purified MAO A, with low Ki values of 5, 69, 15, and 48 nM, respectively. The inhibitors interacted with the covalently bound flavin to induce distinct spectral changes, the magnitude of which correlated with the efficacy of the inhibition. The more effective inhibitors could be in situ inhibitors of MAO A.

Carbolines↗
PubMed1997

Evaluation of chemotherapy response in patients with advanced head and neck cancer using [F-18]fluorodeoxyglucose positron emission tomography.

BACKGROUND: [F-18]Fluorodeoxyglucose (FDG)-positron emission tomography (PET) can measure the metabolic activity of tissues; FDG-PET may be able to predict response to chemotherapy by identifying changes in tumor metabolism. Measurement of response to treatment may help improve survival in the management of advanced head and neck cancer. We evaluated this particular use of FDG-PET in patients participating in a neoadjuvant organ-preservation protocol using taxol and carboplatin and compared pathologic response after chemotherapy with changes in tumor metabolism measured by FDG-PET. METHODS: Serial FDG-PET studies (n = 56) were performed in patients (n = 28) with stage III/IV head and neck cancer participating in a neoadjuvant organ-preservation protocol. The FDG-PET studies were performed before and after chemotherapy. All patients had tissue biopsies before and after chemotherapy. Patients were classified as pathologic complete response (PCR) or residual disease (RD) based on tissue biopsies. Visual analysis of PET scans was performed to identify patients with complete response by PET, and these findings were compared with pathology results. Metabolic changes were also evaluated using standardized uptake ratios (SUR) of FDG. RESULTS: The sensitivity and specificity of PET for residual cancer after therapy was 90% (19/21) and 83% (5/6), respectively. Two patients had initially negative biopsies and positive PET studies for persistent disease. Pathology review and rebiospy led to confirmation of the PET results in these cases, giving a sensitivity of 90% for initial tissue biopsy. CONCLUSIONS: In this preliminary analysis, FDG-PET was accurate in classifying response to chemotherapy in most patients. Fluorodeoxyglucose-PET may identify residual viable tumor when it is otherwise undetectable.

Animals↗
PubMed1997

Seroimmunological characteristics of Korean workers exposed to toluene diisocyanate.

Since type I allergy caused by specific IgE antibodies may play principal roles and IgG antibody-mediated reactions have been thought to be involved in some parts of the pathogenesis, this study was performed to investigate the role of IgE- or IgG-mediated hypersensitivity reactions in development of toluene diisocyanate (TDI) asthma in Korean workers. For 81 TDI spray painters, self-administrative questionnaires and direct interviews on respiratory symptoms, chest auscultation, and measurements of forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) were performed. The TDI concentration in their working environments was measured. Levels of serum IgE and IgG specific to TDI were estimated by radioallergosorbent test (RAST) and ELISA using p-tolyl isocyanate-human serum albumin (TMI-HSA) as the antigen. When sputum, cough, and dyspnea aggravated by work or wheezing existed, when FVC or FEV1.0 was less than 80% of the normal reference value, or when IgE RAST for TDI was positive, the peak expiratory flow rate (PEFR) was recorded four times per day for over 2 weeks. If decrease of PEFR was over 20% of baseline PEFR and changing pattern of PEFR was closely related to workshift in time, then a diagnosis of TDI asthma was made. Changing patterns of PEFR of 8 (9.9%) workers corresponded to the diagnostic criteria of TDI-related occupational asthma. Levels of the specific IgE were increased in 9 (11.1%) of the 81 subject workers and in 3 (37.5%) of the 8 PEFR-positive workers. Levels of the specific IgG were increased in 9 (11.1%) workers, and in only 1 (12.5%) of the asthmatics sensitive to TDI. Neither elevated TDI-specific IgE levels nor PEFR test positivities were associated with increased IgG levels. The mean titer of the PEFR-test-positive workers was slightly lower than that of the PEFR-negative workers and that of the IgE RAST-positive workers lower than that of the test-negative workers, but there was no statistical significance. These results suggest that IgG is not deeply involved in the pathogenesis of TDI-induced occupational asthma in Korean workers.

Adult↗
PubMed1997

Mevalonic acidemia: first case of Japan.

Mevalonic acidemia is a rare metabolic disorder due to mevalonate kinase deficiency which affects the biosynthesis of cholesterol and nonsterol isoprenes. We report the first case of Japan. The clinical course is characterized by intrauterine growth retardation, postnatal growth failure, intractable diarrhea, liver dysfunctions and death at three months of age. Dysmorphic features including triangular face, protrusion of forehead, hypertelorism, low set ears and micrognathism were noted. High mevalonic acid level was found by GC/MS.

Fatal Outcome↗
PubMed1997

Lipids and ultrastructure of Thraustochytrium sp. ATCC 26185.

As a representative of a genus with species considered to be potential commercial producers of the nutritionally important polyunsaturated fatty acid docosahexaenoic acid (DHA), Thraustochytrium sp. ATCC 26185 was investigated to determine its potential for DHA production and lipid composition. Cells from liquid shake cultures contained 32% (w/w) lipid, 18% of which was nonsaponifiable lipid. The major saturated fatty acids (14:0 and 16:0) comprised up to 59% of the total fatty acids, and DHA was up to 25% after 6 d incubation. Squalene represented 63% of the nonsaponifiable lipid, and cholesterol composed 41% of the total sterols. The phospholipids expected for eucaryotic microbes were detected with phosphatidylcholine as the major phospholipid at 76% of the total. The ultrastructure of this species was similar to other Thraustochytrium species except that the cells did not have surface scales and they contained unusual membrane-like structures that appeared to be associated with oil formation.

Chromatography, Gas↗
PubMed1997

Acquired choledochal cyst from anomalous pancreatobiliary duct union.

The high incidence of anomalous pancreatobiliary duct union (APBDU) in children who have a choledochal cyst has been well documented. Additionally, cylindrical dilatation of the bile duct has been reproduced in animal models by anastomosing the pancreatic duct to the bile duct. In recent years, APBDU has been considered a possible etiologic factor in the formation of a choledochal cyst. The authors observed a progressive cylindrical dilatation of the common bile duct in a 6-year-old boy over an 18-month period. An operative cholangiogram showed a type Ic choledochal cyst and a type B APBDU (Todani classification). This clinical experience suggests that a normal common bile duct in children can be progressively dilated and become an acquired choledochal cyst arising as a complication of the preexisting APBDU.

Bile Ducts↗
PubMed1997

Nasal obstruction as a risk factor for sleep-disordered breathing. The University of Wisconsin Sleep and Respiratory Research Group.

Nasal obstruction frequently has been associated with sleep-disordered breathing as a potential etiologic factor. Nasal obstruction results in pathologic changes in airflow velocity and resistance. Experimentally produced nasal obstruction increases resistance and leads to sleep-disordered breathing events, including apnea, hypopnea, and snoring. Clinical research examining the correlation between nasal obstruction and sleep-disordered breathing is limited, especially in regard to patients with conditions that increase nasal resistance, such as rhinitis and sinusitis. To further identify risk factors for sleep-disordered breathing, the role of chronic and acute nasal congestion was investigated in a population-based sample. Data on nasal congestion history and sleep problems were obtained by questionnaire (n = 4927) and by objective inlaboratory measurement (n = 911). Participants who often or almost always experienced nighttime symptoms of rhinitis (5 or more nights a month) were significantly (p < 0.0001) more likely to report habitual snoring (3 to 7 nights a week), chronic excessive daytime sleepiness, or chronic nonrestorative sleep than were those who rarely or never had symptoms. Habitual snorers had significantly (p < 0.02) lower air flow than nonsnorers, although a linear relation between decreased airflow and sleep-disordered breathing severity did not exist. Participants who reported nasal congestion due to allergy were 1.8 times more likely to have moderate to severe sleep-disordered breathing than were those without nasal congestion due to allergy. Men and women with nasal obstruction, especially chronic nighttime symptoms of rhinitis, are significantly more likely to be habitual snorers, and a proportion also may have frequent episodes of apnea and hypopnea, indicative of severe sleep-disordered breathing. Because allergic rhinitis is a common cause of nasal obstruction and it is a modifiable risk factor, further study of this association is warranted.

Adult↗
PubMed1997

Torsional creep of polycarbonate orthodontic brackets.

OBJECTIVE: Polycarbonate materials are known to exhibit creep. The purpose of this study was to investigate torsional creep of polycarbonate orthodontic brackets. METHODS: Four polycarbonate, one metal, and one ceramic brackets were tested. An in vitro torque apparatus was constructed which applied 2000 g-mm of torque to the bracket slot via a cantilever beam perpendicular to the bracket face. The apparatus was placed in a 37 degrees C water bath. Measurements of the angle of the cantilever beam were made at various times from 1 to 28 d. The initial angular change on loading and subsequent changes with time were compared with ANOVA and Tukey tests at p < 0.5. RESULTS: All but one bracket showed the majority of creep by 2 d. Creep was not judged to be clinically significant for the metal, ceramic and the metal slot-reinforced brackets. The polycarbonate bracket without metal slots demonstrated significantly more creep (p < 0.05) than the polycarbonate reinforced with a metal slot, metal and ceramic brackets. SIGNIFICANCE: Clinically significant bracket slot angle (torque) change due to creep can occur when using polycarbonate brackets without metal slot reinforcement.

Analysis of Variance↗
PubMed1997

Identification of sequence requirement for the origin of DNA replication in human papillomavirus type 18.

DNA replication of human papillomavirus type 18 is dependent on viral proteins E1 and E2 and the subsequent interaction of these proteins with the viral origin of replication. Using a site-directed mutagenesis analysis, we examined the sequence requirement for the DNA replication of the human papillomavirus type 18. We showed that both the E1BS palindrome and E2BS are the major determinants of the HPV replication efficiency. In particular, abolishing E2 binding sites demonstrated that E2BS makes a significant contribution towards HPV-18 DNA replication. Each part of the 18-bp inverted repeat sequence of the E1BS motif showed a clear functional difference between two regions: nt 13-21 (3' half segment) is evidently more important for replication than nt 4-12 (5' half segment). Besides E1BS and E2BS, cis-acting elements such as the poly-A6 track, perhaps the YY1 binding site, and the TATA box sequence within the origin region exhibited some contributions to optimum replication. In addition, inserting an enhancer region to the minimum origin DNA derivatives increased replication approximately 2-fold compared with the wild type levels and showed some compensational effects on loss of the cis-element within the HPV-18 minimum origin, suggesting that an enhancer region is required for efficient replication of the papillomavirus origin. These results suggest that the formation of an E1-E2-ori complex is important for replication, and other sequences near the E1 and E2 binding sites assist E1-E2-ori-mediated DNA replication in vivo.

Base Sequence↗
PubMed1997

Simultaneous determination of methylparaben, propylparaben and thimerosal by high-performance liquid chromatography and electrochemical detection.

A reversed-phase high-performance liquid chromatographic method using amperometric detection has been developed for the analysis of methylparaben, propylparaben and thimerosal. The liquid chromatographic separation of the three preservatives was made possible on a C18-bonded silica column with a mixed solvent consisting of methanol and aqueous 0.02 M phosphoric acid (59:41, v/v). A potential value of +1.25 V versus Ag/AgCl was chosen for simultaneous analysis. The limits of detection were 1, 2 and 5 ng for a 20 microliters injection volume of methylparaben, propylparaben and thimerosal, respectively. The analysis time of less than 20 min in this study was found to be applicable for routine analysis of these compounds in pharmaceutical products.

Chromatography, High Pressure Liquid↗
PubMed1997

In vitro assessment of the hemodynamic effects of a partial occlusion in a vena cava filter.

PURPOSE: Flow fields surrounding a vena cava filter were studied with a noninvasive method of flow visualization to examine the underlying hemodynamic factors that contribute to its function and patency. METHODS: The photochromic technique was used to measure axial velocity profiles and wall shear stress distributions in a 12F titanium Greenfield filter partially occluded with a simulated volume of entrapped thrombi. These results were compared with similar measurements obtained for an unoccluded filter and with a theoretic prediction of the velocity profile and wall shear stress without a vena cava filter. Shear stress distributions were obtained along the vessel wall and for the partially occluded filter along the surface of the simulated clot. RESULTS: The unoccluded filter was observed to have little effect on the flow field. In the case of the partially occluded filter, the results of these measurements show that caval blood flow is preserved by the creation of an annular region of increased flow around the periphery of the clot. Within this region high shear stresses that develop as a result of the increased flow are observed along the vessel wall and along the surface of the simulated clot. No vortices or turbulence were observed with either the unoccluded or the partially occluded filter. CONCLUSIONS: The elevated levels of shear stress may be a factor in the lysis of trapped clots observed in vivo. Although increased shear stress is reported to cause thrombogenesis in an in vivo study in canines, particularly under turbulent flow conditions, the levels of shear measured in this study around the simulated clot were well below such values.

Algorithms↗
PubMed1997

Rollback in posterior cruciate ligament-retaining total knee arthroplasty. A radiographic analysis.

A clinical and radiographic study of 49 posterior cruciate ligament-retaining total knee arthroplasties in 38 patients (11 bilateral, 27 unilateral), using prostheses of the same design, was undertaken to quantify the amount of in vivo rollback (ie, the anteroposterior translation of the tibia with respect to the femur during flexion). The mean difference in the distances between the contact points of the knees in full extension and in 90 degrees flexion (ie, the rollback distance) was a posterior translation of the contact point of -0.2 mm (-12.7 to +7l6 mm; SD, 4.7 mm) relative to the prosthetic tibial tray, corresponding to an average translation of 0% of the prosthetic tibial tray depth, and -0.2 mm (-12.5 to +9.1 mm; SD, 4.8 mm) relative to the tibia itself, corresponding to an average translation of 0% of the true tibial surface depth. The differences between the rollback values obtained from the 90 degrees and full-extension radiographs relative to the prosthetic tibial tray (P = .63) and the true tibia (P = .89) were not statistically significant. Intraobserver (P = .27-.50) and interobserver (P = .13-.72) reliability tests showed that the differences between radiographic measurements taken by the same observer at two different points in time and by two different observers were not statistically significant. No correlations were found between the degree of translation of the tibiofemoral contact point relative to the prosthetic tibial tray and the posterior tilt of the tibial tray (R2 = .12), the preoperative tibiofemoral angle (R2 = .34), and the postoperative tibiofemoral angle (R2 = .027). No correlations were found between the degree of translation of the tibiofemoral contact point relative to the true tibia and the posterior tilt of the tibial tray (R2 = .16), the preoperative tibiofemoral angle (R2 = .14), and the postoperative tibiofemoral angle (R2 = .034). In conclusion, this study indicated no demonstrable rollback occurring in the posterior cruciate ligament-retaining total knee arthroplasty used in this study.

Aged↗
PubMed1997

Tourette's syndrome in patients referred for allergy evaluation.

BACKGROUND: Tourette's syndrome is a relatively common disorder that may present as a spectrum that can include both motor and behavioral features. METHODS: We report four patients referred to allergists to rule out atopy as a reason fro their presumed respiratory symptoms who were subsequently found to have Tourette's syndrome. A review of the literature was also performed using Medline. RESULTS: The symptoms of Tourette's syndrome may overlap those associated with allergy involving the respiratory tract. There is little published information on the association of Tourette's syndrome with atopy. CONCLUSIONS: Allergists should be aware of Tourette's syndrome and the variable clinical spectrum of this disorder as Tourette's syndrome patients may be referred prior to the diagnosis of Tourette's syndrome.

Child↗