Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 649 records · Page 36Linked to original sources

PubMed1998

Goodness-of-fit tests for the additive risk model with (p > 2)-dimensional time-invariant covariates.

This paper presents methods for checking the goodness-of-fit of the additive risk model with p(> 2)-dimensional time-invariant covariates. The procedures are an extension of Kim and Lee (1996) who developed a test to assess the additive risk assumption for two-sample censored data. We apply the proposed tests to survival data from South Wales nikel refinery workers. Simulation studies are carried out to investigate the performance of the proposed tests for practical sample sizes.

Biometry↗

PubMed1998

Absorptive function following small intestinal transplantation.

All studies involving small intestinal transplantation and absorptive function are reviewed. The effects ischemia-reperfusion, lymphatic disruption, denervation, rejection, immunosuppressive medication, and infection are elucidated as far as the studies allow. Species differences are discussed. Conclusions regarding the major absorptive defects are drawn.

Denervation↗

PubMed1998

Prolonged hormone secretion from neuroendocrine cells of Aplysia is independent of extracellular calcium.

The role of Ca2+ from extracellular and intracellular sources in stimulating neurosecretion was investigated in four experiments using neuroendocrine bag cells of the marine mollusk Aplysia. (i) Bag cells were treated with either an extracellular calcium chelator (BAPTA) or Co(2+)-substitution within 30 s after onset of an electrical afterdischarge to prevent influx of Ca2+ from extracellular fluid. These treatments shortened the duration of the afterdischarge, but did not significantly affect the overall pattern or total amount of egg laying hormone (ELH) secretion, suggesting that extracellular Ca2+ is not required for maintenance of ELH release. (ii) Substitution of Ba2+ for Ca2+ has previously been shown to support bag cell afterdischarges that trigger transient elevations in intracellular Ca2+. We showed that this treatment also stimulates ELH secretion, suggesting that Ca2+ release from intracellular stores can stimulate ELH secretion. (iii) To raise intracellular Ca2+ levels in the absence of an afterdischarge, the calcium ionophore X537A was used to transport Ca2+ across plasma and organelle membranes. When this treatment was combined with extracellular calcium chelators so that the only source of Ca2+ was from intracellular compartments, ELH secretion was stimulated. Taken together, these findings are consistent with the hypothesis that release of Ca2+ from intracellular stores is sufficient to stimulate ELH secretion.

Animals↗

PubMed1998

Licochalcone A: an inducer of cell differentiation and cytotoxic agent from Pogostemon cablin.

Licochalcone A (1), ombuin (2), and 5,7-dihydroxy-3',4'-dimethoxyflavanone (3) were isolated from the aerial parts of Pogostemon cablin by cytotoxicity-guided fractionation. Compound 1 showed in vitro cytotoxicity and Pl-PLC gamma 1 inhibition activity. Treatment of promyelocytic leukemia cells (HL-60) with compound 1 induced terminal differentiation with the generation of monocyte using nonspecific acid esterase assay.

3T3 Cells↗

PubMed1998

Cytotoxic sesquiterpene lactones from Inula britannica.

Cytotoxicity-guided fractionation of the flowers of Inula britannica led to the isolation of four sesquiterpene lactones, 4 alpha, 6 alpha-dihydroxyeudesman-8 beta, 12-olide (1), ergolide (2), 8-epi-helenalin (3), and bigelovin (4). Compound 1 was isolated as a new natural product. These compounds showed cytotoxicity against human tumor cell lines.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Large-scale phylogenies and measuring the performance of phylogenetic estimators.

Performance measures of phylogenetic estimation methods such as accuracy, consistency, and power are an attempt at summarizing an ensemble of a given estimator's behavior. These summaries characterize an ensemble behavior with a single number, leading to a variety of definitions. In particular, the relationships between different performance measures such as accuracy and consistency or accuracy and error depend on the exact definition of these measures. In addition, it is relatively common to use large-sample behavior to infer similar behavior for small samples. In fact, large-sample results such as the claimed asymptotic efficiency of the maximum-likelihood estimator are often uninformative for small samples. Conversely, small-sample behavior using simulations is sometimes used to imply large-sample behavior such as consistency. However, such extrapolation is often difficult. How the performance of a phylogenetic estimator scales with the addition of taxa must be qualified with respect to whether the whole tree is being estimated or a fixed subset of taxa is being estimated. It must also be qualified with respect to how tree models are sampled. Over the ensemble of all possible trees of a given size, the performance of the estimators for the whole tree estimate suffers when the tree size becomes larger. However, under certain models of cladogenesis, the estimate can improve with the addition of taxa. In fact, at all numbers of taxa there are subsets of tree models that are easier to estimate than others. This suggests that with judicious addition or subtraction of taxa we can move from tree models that are more difficult to estimate at one number of taxa to those that are easier to estimate at another number of taxa.

Analysis of Variance↗

PubMed1998

Monoclonal antibodies define a cellular antigen involved in HTLV-I infection.

The exact mechanism by which the human T cell leukemia viruses (HTLV) infects target cells remains unclear; although some molecules have been identified to be important in viral infection and entry. To investigate these phenomena, we generated a panel of monoclonal antibodies (MAb) against a B cell line (BJAB-WH) which is highly permissive for infection with HTLV. These MAb have been used to further characterize the membrane molecules important for HTLV infection. Three of these MAb designated 4.2.3, 3.3.10, and 11.2.3 were capable of inhibiting syncytium formation induced in human B and T cell lines (i.e., BJAB-WH and SupT-1, respectively) by co-culture with HTLV-I infected MT-2 cells. All of these MAbs immunoprecipitated a 80-85 kDa antigen from the lysates of metabolically labeled BJAB-WH but not from BJAB-CC/84, a noninfectible target cell. The binding of these MAb with different HTLV target cells was analyzed and compared with binding of polyclonal monospecific antisera to the same cell lines. A 80-85 kDa membrane glycoprotein was isolated with an immunoaffinity chromatographic column constructed with MAbs 4.2.3 and 3.3.10. This cellular antigen was capable of inhibiting HTLV I/MT-2 induced fusion. This is the first direct demonstration that a 80-85 kDa cellular glycoprotein is directly involved in HTLV I/II infection and syncytium formation.

Antibodies, Monoclonal↗

PubMed1998

A nucleolar protein that affects mating efficiency in Saccharomyces cerevisiae by altering the morphological response to pheromone.

SSF1 and SSF2 are redundant essential yeast genes that, when overexpressed, increase the mating efficiency of cells containing a defective Ste4p Gbeta subunit. To identify the precise function of these genes in mating, different responses to pheromone were assayed in cells that either lacked or overexpressed SSF gene products. Cells containing null alleles of both SSF1 and SSF2 displayed the normal transcriptional induction response to pheromone but were unable to form mating projections. Overexpression of SSF1 conferred the ability to form mating projections on cells containing a temperature-sensitive STE4 allele, but had only a small effect on transcriptional induction. SSF1 overexpression preferentially increased the mating efficiency of a strain containing a null allele of SPA2, a gene that functions specifically in cell morphology. To investigate whether Ssf1p plays a direct physical role in mating projection formation, its subcellular location was determined. An Ssf1p-GFP fusion was found to localize to the nucleolus, implying that the role of SSF gene products in projection formation is indirect. The region of Ssf1p-GFP localization in cells undergoing projection formation was larger and more diffuse, and was often present in a specific orientation with respect to the projection. Although the function of Ssf1p appears to originate in the nucleus, it is likely that it ultimately acts on one or more of the proteins that is directly involved in the morphological response to pheromone. Because many of the proteins required for projection formation during mating are also required for bud formation during vegetative growth, regulation of the activity or amount of one or more of these proteins by Ssf1p could explain its role in both mating and dividing cells.

Cell Nucleolus↗

PubMed1998

Neurosarcoidosis presenting as hypopituitarism and a cystic pituitary mass.

We report a young woman with clinical hypopituitarism and systemic sarcoidosis involving the lung, gastrointestinal tract, and peripheral lymph nodes. Laboratory evaluation confirmed that cortisol, thyroid indices, insulin-like growth factor 1, follicle-stimulating hormone, luteinizing hormone, and estradiol levels were low, with a normal prolactin. Magnetic resonance imaging revealed a large cystic pituitary lesion compressing the optic chiasm and exhibiting rim but not hypothalamic enhancement. The differential diagnosis included cystic macroadenoma, Rathke's cleft cyst, craniopharyngioma, and simple cyst. A transsphenoidal procedure provided decompression and diagnosis: pathology was consistent with sarcoidosis. Postoperatively, the patient's neurosarcoid disease markedly worsened, requiring hypothalamic irradiation. To our knowledge, this is the first report of intracranial sarcoidosis presenting solely as a cystic pituitary mass. An awareness of this possibility is important to prevent inappropriate neurosurgical intervention and subsequent potential exacerbation of neurosarcoidosis.

Adult↗

PubMed1998

Pharmacokinetics of recombinant human interferon-alpha 2a combined with 5-fluorouracil in patients with advanced colorectal carcinoma.

We evaluated the pharmacokinetics of 5-fluorouracil (5-FU) combined with recombinant human interferon (IFN)-alpha 2a in 10 previously untreated patients with advanced colorectal carcinoma. 5-FU was administered as a continuous i.v. infusion, 750 mg/m2/day for 5 days during week 1. One s.c. injection of IFN-alpha 2a, 9 x 10(6) IU, was administered during week 2. Beginning with week 3, a continuous i.v. infusion of 5-FU 750 mg/m2/day for 5 days was administered in combination with IFN-alpha 2a, 9 x 10(6) IU s.c. three times per week. The combination of 5-FU and IFN-alpha 2a was continued every other week until either 3 months after complete remission or tumor progression. No grade 4 toxicity was observed. Granulocytopenia (two patients), leukopenia (one patient), thrombocytopenia (one patient), stomatitis (two patients), fatigue (one patient) and hand-foot syndrome (one patient) were the major (grade 3) toxic reactions encountered. Overall, one complete and six partial responses were noted. The results of the paired t-test showed no statistically significant differences between the means of the two treatments, 5-FU and 5-FU plus IFN-alpha 2a, with respect to the steady-state plasma concentration, area under the concentration-time curve, total body clearance, or steady-state volume of distribution of 5-FU, or the serum concentration of IFN. We conclude that 5-FU and IFN-alpha 2a do not interact pharmacokinetically at the doses and schedules in the regimen studied.

Adult↗

PubMed1998

Soft-palate reconstruction with a "SCARF" superior-constrictor advancement-rotation flap.

Reconstruction of hemi-soft-palate defects after tumor resection is usually done by means of a regional flap, free-tissue transfer or a prosthesis. These options vary in complexity and have a number of shortcomings. A local myomucosal flap was designed that employs a superior-constrictor advancement-rotation flap (SCARF) to achieve circumferential closure of the velopharynx and to re-establish its valvular sphincteric function. Ten patients underwent a SCARF reconstruction of the velopharynx after 35% to 65% of the soft palate was resected. All patients re-established normal velopharyngeal function without significant phonatory or deglutitive disability. Two patients did require a second-stage reinforcement of the suture line after partial dehiscence. The SCARF reconstruction of the soft palate is simple, fast, and reliable and there is no significant donor site morbidity. Patients resume oral intake earlier than standard reconstructive approaches. The SCARF can be done transorally, which allows for primary resection and discontinuous neck dissection. These factors facilitate short hospitalization and effective use of resources.

Humans↗

PubMed1998

Successive order scattering transport approximation for laser light propagation in whole blood medium.

An analytical solution method of the radiative transport equation, describing light scattering distribution in whole blood, is derived by applying successive order scattering approximation and transport approximation. By separating coherent components of scattered fluxes, the transport equation can be represented in terms of each order scattering flux, and the equations for each order scattering flux have a simplified integration term of scattering contribution that usually makes the solution complicated or even impossible. Also, actual phase function can be used for calculation of angular dependent scattering distribution that is approximated by the sum of the zeroth- and first-order Legendre polynomial in diffusion theory, or the sum of isotropic and coherent components in transport approximation. The method is then used to calculate reflectance from a half-space blood medium. It is found that first-order scattering flux alone produces a good agreement with experimental data and higher-order scattering fluxes are negligible in whole blood.

Anisotropy↗

PubMed1998

National survey of Korean dentists' knowledge and opinions: dental caries etiology and prevention.

OBJECTIVE: Dentists have the potential to influence what their patients know and do regarding dental caries prevention. The practices of dentists and what they tell their patients are influenced, in part, by their own knowledge and opinions. The purposes of this study were to determine the level of knowledge and opinions about caries etiology and prevention among Korean dentists and to describe related factors. METHODS: A pretested, 27-item questionnaire was mailed to 2,047 dentists, selected by a stratified random sampling allocated proportionately. A postcard reminder was sent to all dentists after one week. Nonrespondents were sent additional complete mailings after three, seven, and nine weeks. The response rate was 83 percent (n = 1,700 dentists). RESULTS: Analysis of six factors thought to be related to knowledge about caries etiology and prevention showed that recent graduates and dentists who worked in public health centers were likely to be more knowledgeable about caries etiology and prevention than their counterparts (P < .05). In regression analysis of perceived effectiveness of caries-preventive procedures for children, recent graduates, males, and dentists who worked in public health centers tended to rate caries-preventive procedures more effective than other dentists (P < .05). Dentists who had experience with school-based preventive programs and dentists in rural areas were likely to rate caries-preventive procedures for adults more effective than other dentists (P < .05). CONCLUSIONS: Overall, results of this study suggest that the majority of dentists do not know current information concerning etiology and prevention of dental caries, mechanisms of action of fluoride, and effectiveness of preventive procedures for children and adults. Efforts to enhance the level of knowledge and practices of Korean dentists about caries prevention should focus on strategies to educate older graduates and female dentists, especially those in private practice.

Adult↗

PubMed1998

Identification of a sequence motif that confers SecB dependence on a SecB-independent secretory protein in vivo.

SecB is a cytosolic chaperone which facilitates the transport of a subset of proteins, including membrane proteins such as PhoE and LamB and some periplasmic proteins such as maltose-binding protein, in Escherichia coli. However, not all proteins require SecB for transport, and proteins such as ribose-binding protein are exported efficiently even in SecB-null strains. The characteristics which confer SecB dependence on some proteins but not others have not been defined. To determine the sequence characteristics that are responsible for the SecB requirement, we have inserted a systematic series of short, polymeric sequences into the SecB-independent protein alkaline phosphatase (PhoA). The extent to which these simple sequences convert alkaline phosphatase into a SecB-requiring protein was evaluated in vivo. Using this approach we have examined the roles of the polarity and charge of the sequence, as well as its location within the mature region, in conferring SecB dependence. We find that an insert with as few as 10 residues, of which 3 are basic, confers SecB dependence and that the mutant protein is efficiently exported in the presence of SecB. Remarkably, the basic motifs caused the protein to be translocated in a strict membrane potential-dependent fashion, indicating that the membrane potential is not a barrier to, but rather a requirement for, translocation of the motif. The alkaline phosphatase mutants most sensitive to the loss of SecB are those most sensitive to inhibition of SecA via azide treatment, consistent with the necessity for formation of a preprotein-SecB-SecA complex. Furthermore, the impact of the basic motif depends on location within the mature protein and parallels the accessibility of the location to the secretion apparatus.

Adenosine Triphosphatases↗

PubMed1998

Survey of Klebsiella pneumoniae strains producing extended-spectrum beta-lactamases: prevalence of SHV-12 and SHV-2a in Korea.

Fifty-three clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae collected from three hospitals in Korea were investigated for phenotypical and genotypical characterizations. Among these, 39 strains (74%) were shown by isoelectric focusing to carry SHV-type beta-lactamases: 27 strains showed the pI 8.2 beta-lactamase, and another 12 strains showed the pI 7.6 beta-lactamase. The SHV gene of each of these strains was amplified by PCR, followed by nucleotide sequencing analysis. The gene of the pI 8.2 beta-lactamase was found to be identical to the sequences encoding SHV-12, and the gene of the pI 7.6 beta-lactamase was identical to the sequences encoding SHV-2a. A total of eight cefoxitin-resistant strains were found to have the plasmid-mediated AmpC-type beta-lactamase, with a pI of 8.0, and this was confirmed to be CMY-1 beta-lactamase by PCR and hybridization analysis. Noteworthy in this study is the fact that SHV-12 and SHV-2a have been the most commonly identified SHV-type ESBLs in Korea.

Anti-Bacterial Agents↗

PubMed1998

A protein critical for a Theiler's virus-induced immune system-mediated demyelinating disease has a cell type-specific antiapoptotic effect and a key role in virus persistence.

TO subgroup strains of Theiler's murine encephalomyelitis virus (TMEV) induce a persistent central nervous system infection and demyelinating disease in mice. This disease serves as an experimental model of multiple sclerosis (MS) because the two diseases have similar inflammatory white matter pathologies and because the immune system appears to mediate demyelination in both processes. We previously reported (H. H. Chen, W. P. Wong, L. Zhang, P. L. Ward, and R. P. Roos, Nat. Med. 1:927-931, 1995) that TO subgroup strains use an alternative initiation codon (in addition to the AUG used to synthesize the picornavirus polyprotein from one long open reading frame) to translate L*, a novel protein that is out of frame with the polyprotein and which plays a key role in the demyelinating disease. We now demonstrate that L* has antiapoptotic activity in macrophage cells and is critical for virus persistence. The antiapoptotic action of L* as well as the differential translation of L* and virion capsid proteins may foster virus persistence in macrophages and interfere with virus clearance. The regulation of apoptotic activity in inflammatory cells may be important in the pathogenesis of TMEV-induced demyelinating disease as well as MS.

Animals↗

PubMed1998

Prediction of the effectiveness of long-term beta blocker treatment for dilated cardiomyopathy by signal averaged electrocardiography.

OBJECTIVE: To determine whether the effectiveness of long-term beta blocker treatment for idiopathic dilated cardiomyopathy can be predicted by signal averaged electrocardiography (ECG). PATIENTS: 31 patients with dilated cardiomyopathy and without bundle branch block were included in a retrospective study and 16 in a prospective study. METHODS: A signal averaged ECG was recorded before beta blocker treatment, and three variables were measured from the vector magnitude: QRS duration, root mean square voltage for the last 40 ms (RMS40), and duration of the terminal low amplitude signals (< 40 microV) (LAS40). In the retrospective study, these variables were compared among good responders (showing > or = 0.10 increase in ejection fraction 12 months after start of beta blocker treatment) and poor responders without such improvement. The validity of the signal averaged ECG criteria for prediction of the response to beta blocker treatment was examined in the prospective study. RESULTS: In the retrospective study, good responders (n = 16) had a shorter QRS duration (mean (SD): 122.9 (11) v 138 (14.4) ms, p < 0.005) and LAS40 (33.1 (8.9) v 42.5 (7.8) ms, p < 0.005), and a higher RMS40 (31.6 (16.3) v 19.0 (10.3) microV, p < 0.02) than poor responders (n = 15). Signal averaged ECG criteria for good response were defined as two or more of the following: QRS duration < 130 ms, RMS40 > 20 microV, LAS40 < 40 ms (sensitivity 81%, specificity 73%). In the prospective study, six of seven patients who met these criteria showed a good response to the beta blocker treatment, while eight of nine who did not showed a poor response (chi 2 = 6.1, p < 0.02). The signal averaged ECG criteria gave a sensitivity of 86% and a specificity of 89% for predicting the effectiveness of beta blocker treatment. CONCLUSIONS: A signal averaged ECG might be useful in predicting the effectiveness of beta blocker treatment for dilated cardiomyopathy.

Adrenergic beta-Antagonists↗

PubMed1998

Biological activities of a novel lectin derived from silkworm faeces: characteristic changes of mouse peritoneal macrophages by the lectin.

A novel lectin derived from silkworm faeces, named NUE, activates phagocytosis of mouse peritoneal macrophages. At this time, significant morphological changes of the cells take place. NUE-treated macrophages formed projection-like neurocytes within 12 hr of treatment, and appeared somewhat flat in shape with the activation of cell growth. Associated with the morphological changes, actin was organized in dot-like structures corresponding to cell-substratum contact sites in NUE-treated macrophages. Vinculin, a cytoskeletal protein involved in microfilament-membrane interaction, formed doughnut-like rings matching the actin-dots, called "podosomes". Furthermore, observation by interference reflection microscopy showed that NUE-treated macrophages adhered more strongly to the substratum at local areas. According to these changes, more proteins associated with cell-substratum contact sites became to detergent-resistant. It was shown that NUE changed adhesive form of mouse peritoneal macrophages structurally and qualitatively.

Animals↗