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Biomedical subjects

K Yi

Publications and source records attributed to K Yi.

16 recordsLinked to original sources
PubMed2004

Porphyrin-based compounds exert antibacterial action against the sexually transmitted pathogens Neisseria gonorrhoeae and Haemophilus ducreyi.

A series of porphyrin based compounds without (nMP) or with (MP) metals were found to have potent bactericidal action in vitro against the sexually transmitted pathogens Neisseria gonorrhoeae and Haemophilus ducreyi. nMP and MP did not show bactericidal activity against five species of lactobacilli. An MP containing gallium had the capacity to block a gonococcal infection in a murine vaginal model, indicating that its development as a topical microbicide to block sexually transmitted bacterial infections is warranted. In contrast to other bacterial species, loss of the gonococcal haemoglobin uptake system encoded by hpuB or energy supplied through the TonB-ExbB-ExbD system did not significantly affect levels of MP-susceptibility in gonococci. In contrast, mutations in gonococci that inactivate the mtrCDE-encoded efflux pump were found to enhance gonococcal susceptibility to nMPs and MPs while over-production of this efflux pump decreased levels of gonococcal susceptibility to these compounds.

Animals↗
PubMed2003

Actins from plant and animal sources tend not to form heteropolymers in vitro and function differently in plant cells.

Pollen and skeletal muscle actins were purified and labeled with fluorescent dyes that have different emission wavelengths. Observation by electron microscopy shows that the fluorescent actins are capable to polymerize into filamentous actin in vitro, bind to myosin S-1 fragments, and have a critical concentration similar to unlabeled actin, indicating that they are functionally active. The globular actins from two sources were mixed and polymerized by the addition of ATP and salts. The copolymerization experiment shows that when excited by light of the appropriate wavelength, both red actin filaments (pollen actin) and green actin filaments (muscle actin) can be visualized under the microscope, but no filaments exhibiting both green and red colors are detected. Furthermore, coprecipitations of labeled pollen actin with unlabeled pollen and skeletal muscle actin were performed. Measurements of fluorescent intensity show that the amount of labeled pollen actin precipitating with pollen actin was much higher than that with skeletal muscle actin, indicating that pollen and muscle actin tend not to form heteropolymers. Injection of labeled pollen actin into living stamen hair cells results in the formation of normal actin filaments in transvacuolar strands and the cortical cytoplasm. In contrast, labeled skeletal muscle actin has detrimental effects on the cellular architecture. The results from coinjection of the actin-disrupting reagent cytochalasin D with pollen actin show that overexpression of pollen actin prolongs the displacement of the nucleus and facilitates the recovery of the nuclear position, actin filament architecture, and transvacuolar strands. However, muscle actin perturbs actin filaments when injected into stamen hair cells. Moreover, nuclear displacement occurs more rapidly when cytochalasin D and muscle actin are coinjected into the cell. It is concluded that actins from plant and animal sources behave differently in vitro and in vivo and that they are functionally not interchangeable.

Actins↗
PubMed2001

Antibodies to loop 6 of the P2 porin protein of nontypeable Haemophilus influenzae are bactericidal against multiple strains.

The P2 porin protein is the most abundant protein in the outer membrane of nontypeable Haemophilus influenzae (NTHI). Analysis of sequences of P2 from different strains reveals the presence of both heterogeneous and conserved surface-exposed loops of the P2 molecule among strains. The present study was undertaken to test the hypothesis that antibodies to a conserved surface-exposed loop are bactericidal for multiple strains of NTHI and could thus form the basis of vaccines to prevent infection due to NTHI. Polyclonal antiserum to a peptide corresponding to loop 6 was raised and was immunopurified over a loop 6 peptide column. Analysis of the antibodies to whole organisms and peptides corresponding to each of the eight loops of P2 by immunoassays revealed that the antibodies were highly specific for loop 6 of P2. The immunopurified antibodies bound to P2 of 14 of 15 strains in immunoblot assays. These antibodies to loop 6 demonstrated complement-mediated bactericidal killing of 8 of 15 strains. These results support the concept of using conserved regions of the P2 protein as a vaccine antigen.

Amino Acid Sequence↗
PubMed2000

Development of a serological test for Haemophilus ducreyi for seroprevalence studies.

We developed a new enzyme immunoassay (rpEIA) for use in determining the seroprevalence of chancroid. Three highly conserved outer membrane proteins from Haemophilus ducreyi strain 35000 were cloned, overexpressed, and purified from Escherichia coli for use as antigens in the rpEIA. Serum specimens from patients with and without chancroid were assayed to determine optimum sensitivity and specificity and to establish cutoff values. On the basis of these data, rpEIA was found to be both sensitive and specific when used to test a variety of serum specimens from patients with genital ulcers and urethritis and from healthy blood donors.

Antibodies, Bacterial↗
PubMed2000

Surgical correction for lower lid epiblepharon in Asians.

BACKGROUND/AIMS: Epiblepharon is a congenital lid anomaly in which a fold of skin and underlying orbicularis muscle push the lashes against the eyeball. It is important to get a good lash eversion effect without forming a prominent lid crease in Asian patients. The surgical effect of this rotating suture technique was evaluated. METHODS: Surgical correction for epiblepharon was performed on 197 patients and the results analysed in 169 patients who had been followed for 1 month or more. After subciliary incision, several buried 8-0 nylon sutures were placed to allow adhesion between the tarsal plate and the subcutaneous tissue of the upper skin flap with minimal resection of pretarsal orbicularis and redundant skin. RESULTS: 156 patients (92.3%) showed satisfactory results during 7.1 months of average follow up. Reoperation was performed only on two patients out of 13 because of mildness of symptoms and signs. Complications were minimal including suture abscesses in four patients and wound dehiscence in one. CONCLUSION: The rotating suture technique was very effective in repairing epiblepharon without forming a prominent lower eyelid crease.

Adolescent↗
PubMed1999

Expression and characterization of anti-NCA-95 scFv (CEA 79 scFv) in a prokaryotic expression vector modified to contain a Sfi I and Not I site.

The CEA 79 antibody has been used in bone marrow scintigraphy for the differential diagnosis of skeletal tumors and the evaluation of the bone marrow status of patients with various hematological disorders. The specific localization of radio-labeled CEA 79 antibody in bone marrow depends on its reactivity with NCA-95 (nonspecific cross-reacting antigen-95) present on the surface and in the cytosol of human granulocytes and myelopoietic cells. To make a CEA 79 scFv molecule that would be less immunogenic and more penetrating than the intact mouse immunoglobulin, we constructed a pRSET Sfi I/Not I expression vector. The scFv gene was then excised from a pCANTAB 5 E phage display vector by digestion with Sfi I and Not I and inserted into the pRSET Sfi I/Not I expression vector. Upon transformation of a BL21(DE3)pLysS strain of E. coli, CEA 79 scFv became expressed in inclusion bodies requiring a renaturation process for solubilization. The final yield of CEA 79 scFv was 5 mg per a liter of culture. The refolded CEA 79 scFv exhibited an affinity (Kd = 2.1 x 10(-9) M) equivalent to that of the original CEA 79 antibody (K(d) = 3.3 x 10(-9) M) and the same immunoreactivity to CEA and NCA-95 in Western blots and in immunohistochemical staining experiments.

Amino Acid Sequence↗
PubMed1999

[Unfolded intraocular lens implantation through a 6 mm sutureless incision].

OBJECTIVE: To evaluate the therapeuitic effects of phacoemusification and unfolded iutraoculavr lens (IOL) implantation through a 6 mm sutureless incision. METHODS: A 6 mm sclera tunnel incision was made at 12 o'clock tangent of the posterior limbus and unfolded polymethylmethacrylate(PMMA) IOL implantation was operated in 50 cases (55 eyes); 53 eyes were finished without suture after phacoemusification and 2 eyes were done with extra capsule cataract extration(ECCE) because of the broken posterior capsular. RESULTS: Postoperatively, the visual acuity was 0.6 or more in 92.4% of the eyes and 1.0 or more in 50.9% of the eyes at one week; 0.6 or more in 98.1% of the eyes and 1.0 or more in 67.9% of the eyes at one month. The mean postoperative astigmatism was 0.63 +/- 0.36 D at one week and 0.61 +/- 0.33 D at one month. There was no statistical difference between the mean preoperative astigmatism(0.60 +/- 0.48 D) and postoperative astigmatism at one week and one month (P > 0.05). CONCLUSION: The technique of phacoemusification and PMMA IOL implantation through a 6 mm sutureless incision can reduce early postoperative astigmatism, shorten the period of visual rehabilitation.

Aged↗
PubMed1997

Mechanisms of recurrent otitis media: importance of the immune response to bacterial surface antigens.

Otitis-prone children experience recurrent episodes of otitis media due to nontypeable H. influenzae (NTHI). A protective immune response occurs following infection, but this immune response is specific for the infecting strain, leaving the child susceptible to infection by other strains of NTHI. Little is known about the mechanism by which a strain-specific antibody response occurs to nonencapsulated bacteria. To explore the mechanism by which this strain-specific response occurs, animals were inoculated with whole bacterial cells and the antibody response was studied. The antibody response was predominantly directed to a highly strain-specific, immunodominant surface loop on the major outer membrane protein. This exquisitely restricted immune response leaves the host susceptible to recurrent infections by many strains of NTHI. The ability of the bacterium to direct the host to make a strain-specific antibody response has important implications in understanding the immune response to otitis media due to NTHI and in designing strategies for vaccine development.

Antigens, Bacterial↗
PubMed1997

Human immune response to nontypeable Haemophilus influenzae in chronic bronchitis.

Nontypeable Haemophilus influenzae (NTHI) causes recurrent respiratory tract infections in patients with chronic bronchitis. To elucidate the human immune response to NTHI, sera from 2 patients with exacerbations of chronic bronchitis due to NTHI were characterized. Both patients developed new bactericidal antibodies following infection. Immunoblot assays with homologous strains revealed antibodies to many antigens, with minimal difference between pre- and postexacerbation sera. By contrast, whole cell radioimmunoprecipitation, which detects antibodies exclusively to epitopes exposed on the bacterial surface, revealed that both patients made new antibodies to a limited number of antigens following infection, including P2, the major outer membrane protein of NTHI. Adsorption experiments showed that strain-specific, surface-exposed epitopes on the P2 molecule are targets for bactericidal antibodies. These results indicate that new bactericidal antibodies following infection by NTHI recognize antigenically heterogeneous surface-exposed epitopes on P2 and other surface proteins of NTHI.

Antibodies, Bacterial↗
PubMed1997

Importance of an immunodominant surface-exposed loop on outer membrane protein P2 of nontypeable Haemophilus influenzae.

Nontypeable Haemophilus influenzae (NTHI) frequently causes recurrent infections of the respiratory tract in humans. Previous indirect evidence suggested that a strain-specific immune response occurs following infection and that this immune response is directed at an immunodominant epitope on the bacterial surface. To test this hypothesis, mice and rabbits were immunized with whole cells of a strain of NTHI and the antiserum was characterized to identify the antigens to which antibodies were directed. All animals made a prominent antibody response to the loop 5 region of the P2 molecule, which is the major outer membrane protein. Rabbit serum showed complement-dependent bactericidal activity. Adsorption of the immune serum with the loop 5 fusion peptide removed bactericidal activity and also abolished reactivity to P2 detected by an immunoblot assay, an enzyme-linked immunosorbent assay, and a radioimmunoprecipitation assay. These data indicate that immunization with whole cells of NTHI results in a prominent antibody response which is directed at epitopes on the loop 5 region of the P2 molecule. Thus, a strain-specific immune response to NTHI occurs as a result of the expression of an immunodominant epitope on the P2 molecule.

Animals↗
PubMed1994

Mapping of a strain-specific bactericidal epitope to the surface-exposed loop 5 on the P2 porin protein of non-typeable Haemophilus influenzae.

The P2 protein is the major outer-membrane protein of non-typeable Haemophilus influenzae (NTHI) and shows extreme heterogeneity among strains. Based on the analysis of antigenic structure, the P2 protein consists of eight potentially surface-exposed loops. Previous studies of monoclonal antibodies (mABs) to a single strain of NTHI showed that P2 contains potentially immunodominant epitopes in loop 5 of the molecule. The goal of the current work is to test the hypothesis that strain-specific and potentially immunodominant epitopes are located in loop 5 of P2 in other strains of NTHI as well. Gene fragments which encode peptides of loop 5 of strains 2019 and 5657 were cloned into an expression vector and subjected to immunoassays with mABs which recognize surface-exposed, bactericidal, strain-specific epitopes. Each mAB recognized loop 5 of the P2 protein of the homologous strain. Analysis of mutant clones with minor amino acid changes showed a loss of reactivity with the mABs. These observations indicate that loop 5 of the P2 molecule contains strain-specific, abundantly expressed surface-exposed epitopes. This further supports the hypothesis that loop 5 is an immunodominant region of the P2 molecule.

Adult↗
PubMed1994

Mapping of bactericidal epitopes on the P2 porin protein of nontypeable Haemophilus influenzae.

The P2 porin protein is the major outer membrane protein of nontypeable Haemophilus influenzae and is a potential target of a protective immune response. Nine monoclonal antibodies (MAbs) to P2 were developed by immunizing mice with nontypeable H. influenzae whole organisms. Each MAb reacted exclusively with the homologous strain in a whole-cell immunodot assay demonstrating exquisite strain specificity. All nine MAbs recognized abundantly expressed surface-exposed epitopes on the intact bacterium by immunofluorescence and immunoelectron microscopy. Each MAb was bactericidal to the homologous strain in an in vitro complement-mediated killing assay. Immunoblot assay of cyanogen bromide cleavage products of purified P2 indicated that MAb 5F2 recognized the 10-kDa fragment, and the other eight MAbs recognized the 32-kDa fragment. Competitive ELISAs confirmed that 5F2 recognized an epitope that is different from the other eight MAbs. To further localize epitopes, MAbs 5F2 and 6G3 were studied in protein footprinting by using reversed-phase high-performance liquid chromatography. Three potential epitope-containing peptides which were reactive in an enzyme-linked immunosorbent assay with both 5F2 and 6G3 were isolated. These peptides were identified by N-terminal amino acid sequence and localized to loops 5 and 8 of the proposed model for P2. Fusion proteins consisting of glutathione S-transferase fused with variable-length peptides from loops 5 and 8 were expressed in the pGEX-2T vector. Immunoblot assay of fusion peptides of loops 5 and 8 confirmed that 5F2 recognized an epitope within residues 338 to 354 of loop 8; 6G3 and the remaining MAbs recognized an epitope within residues 213 to 229 of loop 5. These studies indicate that nontypeable H. influenzae contains bactericidal epitopes which have been mapped to two different surface-exposed loops of the P2 molecule. These potentially protective epitopes are strain specific and abundantly expressed on the surface of the intact bacterium.

Animals↗
PubMedDate not supplied

Computerized densitometric measurement system (CDMS) for the quantitative analysis of diffuse retinal nerve fiber layer atrophy.

Since observable retinal nerve fiber layer (RNFL) atrophy occures several years before irreversible glaucomatous visual field damage in glaucoma patients, quantitative assessment of the diffuse RNFL atrophy has been the goal of many research efforts. The loss of RNFL reflectance is informative sign of the diffuse RNFL atrophy, and appears in monochrome photograph of RNFL. We have, therefore, made a system by which we could measure the loss of RNFL reflectance and named it Computerized Densitometric Measurement System (CDMS). In this method, density profiles concentric with optical disc are extracted from the digitalized RNFL photograph. Density integral of superior and inferior segments in the density profile is used for the assessment of RNFL atrophy. Satisfactory results were obtained about the clinical utility of this method when the CDMS measurement was compared with the indicator of loss of visual function. Intra- and inter-operator reproducibility was also excellent.

Atrophy↗
PubMedDate not supplied

Stressful events among pregnant Salvadoran women: a cross-cultural comparison.

OBJECTIVE: To compare stressful events, including violent episodes, experienced by pregnant Salvadoran women with those experienced by two other groups of low-income, pregnant women living in the United States (non-Salvadoran Hispanics and non-Hispanics) and to examine the association between episodes of violence and drug or alcohol use among the three groups. DESIGN: Comparative, descriptive study. SETTING: Public health prenatal clinics. PARTICIPANTS: One hundred four Salvadoran, 69 non-Salvadoran Hispanic, and 187 non-Hispanic pregnant women. MAIN OUTCOME MEASURES: Difficult Life Circumstances (DLC) scale and psychosocial history assessment. RESULTS: Statistically significant differences were found among the three groups in total DLC scores, F(2, 357) = 14.98, p < .001; reported episodes of violence, F(2, 357 = 17.82, p < .001; and drug or alcohol use, F(2, 357) = 6.33, p < .001. A significant difference was found to the extent that alcohol or drug use accounted for the variance in violence among the three groups, F(3, 360) = 6.28, p < .001. CONCLUSIONS: Cross-cultural comparisons revealed group differences in the number of stressful events, including episodes of violence and alcohol or drug use.

Adult↗