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Biomedical subjects

B Kong

Publications and source records attributed to B Kong.

At least 19 recordsLinked to original sources
PubMed2006

Relative potential for selection of quinolone-resistance-determining-region mutations in Streptococcus pneumoniae by gemifloxacin, gatifloxacin and moxifloxacin.

Serial passage of a clinical isolate of Streptococcus pneumoniae, in the presence of moxifloxacin, gatifloxacin or gemifloxacin, gave rise to resistant isolates. Non-susceptibility as defined by Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) breakpoints arose on Days 10, 11, and 12 with gatifloxacin, gemifloxacin, and moxifloxacin respectively. Moxifloxacin and gatifloxacin selected for a single step quinolone-resistant-determining-region (QRDR) mutation in DNA gyrase (GyrA) on Day 4 and 7 respectively, whereas gemifloxacin selected simultaneously for multi-step mutations in gyrase and topoisomerase IV (ParC) on Day 17 and activated a non-reserpine inhibited efflux mechanism by Day 4. As found in clinical isolates, mutations included Ser-81-Phe and Glu-85-Lys in GyrA and Ser-79-Phe or Asp-83-Tyr in ParC. At high MICs, moxifloxacin showed a previously unreported 4 amino-acid deletion in GyrB as well as a more unusual substitution Ser-79-Leu/Ile in ParC. Gemifloxacin showed a 2- to 16-fold greater activity than moxifloxacin or gatifloxacin against strains with two or more QRDR mutations, however, its potency did not translate to nonsusceptibility and gemifloxacin MIC values were either at or well above the CLSI nonsusceptible breakpoint concentration.

Amino Acid Substitution↗
PubMed2001

Insulin secretion and sensitivity during oral glucose tolerance test in Korean lean elderly women.

Impaired glucose tolerance (IGT) and type 2 diabetes including undiagnosed isolated postchallenge hyperglycemia (IPH) are common in the elderly. The aim of this study was to investigate the insulin secretion and sensitivity in Korean elderly lean diabetic women. Forty-one lean women aged 65-88 years took 2 hr oral glucose tolerance test (OGTT) and were stratified according to the WHO criteria (normal glucose tolerance [NGT], n=20; IGT, n=6; and type 2 diabetics, n=15 including seven IPH). HbA1c and fructosamine progressively increased from the NGT to the diabetic subjects (p=0.006 and p=0.001, respectively). Compared with subjects with NGT, the insulinogenic index, a marker of early insulin secretion and the AUC(ins), a marker of total insulin secretion, decreased significantly in diabetic group [0.53 (-0.44 -1.45) vs. 0.18 (0.00 -1.11), p=0.03 and 306+/-165 vs. 199+/-78 pmol/L, p=0.02 respectively]. A significant difference was found in the AUC(c-peptide) among each group (221+/-59 vs. 206+/-34 vs. 149+/-51 pmol/L, p=0.001 for each). The homeostasis model assessment of insulin resistance (HOMA-IR), a marker of insulin resistance, was not different among the groups. We conclude that compared with NGT subjects, elderly lean women with diabetes have impaired oral glucose-induced insulin secretion but have relatively preserved insulin sensitivity. This suggests that insulin resistance is not necessarily an essential component of Korean elderly lean diabetic women.

Aged↗
PubMed2001

[Gene transfer of CD80 into a human ovarian cancer cell line and induction of cytotoxic T lymphocyte in vitro].

OBJECTIVE: To investigate the proliferation and cytotoxicity of cytotoxic T lymphocyte (CTL) induced by ovarian cancer cells transfected with a CD80 gene containing retroviral vector. METHODS: The ovarian cancer cell line TYK cells were transfected with retro-virus vector PLXSN-hCD80. After geneticin (G418) selection, the CD80 expression of the transfectants was confirmed by flow cytometry. CTL was induced by co-culture of CD80-expressing TYK cells (TYK-hCD80) and peripheral-blood mononuclear cells (PBMC) in the presence of anti-CD3 monoclonal antibody (McAb). Proliferation of PBMC was measured using 3H-Thymidine incorporation assay. The lysis activity of CTL toward tumor cells was determined using methyl thiazolyl tetrazolium (MTT) assay. RESULTS: After transfection and G418 selection, the CD80 expression was proved by flow cytometry. The highest rate of CD80 expression was 84.9%. The TYK cell line expressing high CD80 was named TYK-hCD80. In the presence of anti-CD3 McAb, TYK-hCD80 significantly enhanced proliferation of PBMC than TYK cells (3H-Thymidine incorporation, (40,604 +/- 842) vs (8,000 +/- 594) cpm (P < 0.05). The lysis activity of CTL activated by TYK-hCD80 was higher than that of TYK(P < 0.05). CONCLUSIONS: Ovarian cancer cells expressing CD80 can induce the production of CTLs which have high lysis activity and high proliferation rate in the presence of anti-CD3 McAb. This study may provide the experimental basis for immunogenic therapy of ovarian cancer.

B7-1 Antigen↗
PubMed2001

[Cloning and sequencing of 16S rRNA gene of Phytoplasma CWB1 strain associated with cactus witches' broom].

A 1.5 kb DNA fragment was amplified in DNA samples extracted from Opuntia salmiana porm showed witches'-broom symptom. The result indicates the existence of phytoplasma associated with this disease and this phytoplasma was designated as CWB1. The amplified fragment was ligated to pGEM-T easy vector and then transformed into JM109 strain of E. coli. Cloned DNA fragments were verified by PCR, restriction endonuclease (EcoRI) digestion and sequence analysis. The result revealed that the 16S rRNA gene of CWB1 consists of 1489 bp and shared 99.7% homology with Faba bean phyllody which belongs to phytoplasma 16S rII-C subgroup. So we can classify this strain into phytoplasma 16S rII-C subgroup.

Cloning, Molecular↗
PubMed2001

[Targeted killing effect of mucin-1 single chain antibody targeting, lentivirus-mediated suicide gene therapy and ganciclovir in mucin-1+ ovarian epithelial carcinoma cells].

OBJECTIVE: To investigate the targeted killing effect of mucin-1 single chain antibody targeting, lentivirus-mediated suicide gene therapy and ganciclovir(GCV) in mucin-1+ ovarian epithelial carcinoma cells. METHODS: Mucin-1 single chain antibody targeting lentivirus produced by packaging cell line 293T transduced herpes simplex virus thymidine kinase (HSV-tk) gene into the ovarian epithelial cancer cell line SKOV3 (MUC1+). The infection effect was observed through fluorescence microscopy. Polymerase chain reaction (PCR) and reverse transcription-PCR (RT-PCR) were resorted to demonstrate the successful transduction and transcription of the HSV-tk gene. After administration of GCV, changes of those cells were observed through optical microscopy. The cytotoxicity efficacy of HSV-tk/GCV system was evaluated by methyl thiazolyl tetrazolium method. RESULTS: It was observed through fluorescence microscopy that anti-MUC1 directed lentivirus can specificly infect MUC1+ ovarian cancer cells. A fragment of 600 bp was generated through PCR and RT-PCR which indicated successful transduction and transcription of the HSV-tk gene in SKOV3 cells. Changes of cells followed by administration of GCV were observed with optical microscopy. Significant cytotoxicity efficacy of GCV to SKOV3 was observed. CONCLUSIONS: The HSV-tk gene can be targetedly transducted into MUC1+ ovarian cancer cell line under the mediation of anti-MUC1 directed lentivirus, and such HSV-tk/GCV system has targetingly killing effect on MUC1+ cancer cells.

Antibodies, Viral↗
PubMed2000

[Adenovirus-mediated herpes simplex virus thymidine kinase gene transference and combined drug therapy leads to apoptosis of human epithelial ovarian cancer cells].

OBJECTIVE: To evaluate the treatment and apoptosis effect of adenovirus-mediated herpes simplex virus thymidine kinase (HSV1-tk) gene transference followed by administration of ganciclovir (GCV) and acyclovir (ACV) on ovarian epithelial cancer cells. METHODS: Recombinant adenovirus was amplificated and purified by routine method. The expression of HSV1-tk gene was assayed by polymerase chain reaction (PCR). The efficiency of recombinant Advtk transference was evaluated. The cytotoxicity efficacy of TYK cells that carry HSV1-tk gene was evaluated followed by GCV, ACV administration after the transference of Advtk. The changes and apoptosis of TYK cells that carry HSV1-tk gene were observed by means of analysis of DNA fragmentation and electronic microscopy. RESULTS: Adenovirus was amplificated and purified in large amount. PCR assay showed 404 bp special band. When the multiplicities of infection (MOI) was 100, the transduction rate was 98.9%. The inhibition rates of TYK cells that carry HSV1-tk gene increased with the increase of MOI when the same concentration of GCV, ACV were given. When the MOI was same, the inhibition rates were also increased with the increase concentration of GCV, ACV. Apoptosis of TYK cells that carry HSV1-tk gene after administration of GCV was observed by means of analysis of DNA fragmentation and electronic microscopy. CONCLUSIONS: The HSV1-tk gene can effectively transferred into TYK cells by recombinant replicated-deficient adenovirus vector, GCV, ACV can effectively kill TYK cells that carry HSV1-tk gene in vitro. Apoptosis may be the mechanism of the killing effect.

Acyclovir↗
PubMed1999

Role of phosphate and kinetic characteristics of complete iron release from native pig spleen ferritin-Fe.

The kinetics for complete iron release showing biphasic behavior from pig spleen ferritin-Fe (PSFF) was measured by spectrophotometry. The native core within the PSFF shell consisted of 1682 hydroxide Fe3+ and 13 phosphate molecules. Inhibition kinetics for complete iron release was measure by differential spectrophotometry in the presence of phosphate; the process was clearly divided into two phases involving a first-order reaction at an increasing rate of 46.5 Fe3+/PSFF/min on the surface of the iron core and a zero-order reaction at a decreasing rate of 6.67 Fe3+/PSFF/min inside the core. The kinetic equation [C(PSFF-Fe3+)max - C(PSFF-Fe3+)t](1/2) = Tmax - Tt gives the transition time between the two rates and represents the complex kinetic characteristics. The rate was directly accelerated twofold by a mixed reducer of dithionite and ascorbic acid. These results suggest that the channel of the PSFF shell may carry out multiple functions for iron metabolism and storage and that the phosphate strongly affects the rate of iron release.

Animals↗
PubMed1999

[Study of the inhibitory effects of retrovirus-mediated p16 gene on human ovarian cancer cell line].

OBJECTIVE: To study the inhibitory effects of retro-virus-mediated p16 gene on human ovarian cancer cell line CAOV3. METHODS: Recombinant eukaryotic expression vector pDOR-p16 containing exogenous human wt-p16 cDNA and vector with neomycin resistance gene only were introduced by lipofectamine-mediated gene transfection into CAOV3 cell line which does not express p16 endogenously. By using revert-polymerase chain reaction amplification, mRNA in situ hybridization and immunocytochemistry, the clones obtained were detected for their efficiency of transfection and effects of vector expression and observed for their biologic behavior. RESULTS: Exogenous wt-p16 had successfully been transferred into CAVO3 cells and obtained permanent expression. The growth rate of these transfected CAOV3 cells in regular medium and soft agar was inhibited, and the tumorigenicity in nude mice showed that two in four mice failed to form tumor and the others suffered from tumor later than contrast group by 7 to 14 days. The percentage of phase G1 cells increased and that of phase S cells decreased by analysing cell cycle. The ultrastructural changes of the cells were observed under electron microscope, revealing necrosis and growth retardation. CONCLUSIONS: p16 gene played an important role in generation and development of ovarian carcinoma. This study might provide the experimental evidence for the gene therapy in human ovarian cancer.

Cell Division↗
PubMed1997

The aortic homograft: evolution of indications, techniques, and results in 107 patients.

BACKGROUND: Homograft aortic valve replacement has been performed in 107 patients during the past 7 years. Two primary methods of implantation were used (intraaortic and root replacement). Results of both methods are presented. METHODS: Intraaortic implantation (subcoronary or cylinder technique) was performed in 36 patients (mean age, 54 years) for aortic stenosis or regurgitation (31 patients) and endocarditis (5 patients). Aortic root replacement was performed in 71 patients (mean age, 62 years). The majority (58 patients) had complex root pathologies such as ascending aneurysm, dissection, or prosthetic endocarditis with annular destruction. Early results were assessed with intraoperative or predischarge echocardiography; annual echocardiograms provided long-term follow-up. Left ventricular mass was calculated in patients with long-standing pathology for whom preoperative and postoperative data were available. RESULTS: Early valvular insufficiency was documented in 16 of the 36 intraaortic implants (44%); 9 of these have had progression of the insufficiency. Of the 20 patients who had trivial or no early insufficiency, significant insufficiency has developed in 7 and mild insufficiency has developed in 5. Calculation of left ventricular mass revealed a mean reduction of 11% at 1 year. There has been no mortality, endocarditis, or homograft-related reoperation in the intraaortic group with a mean follow-up of 50 months. The root replacement group had a hospital mortality of 17%. The cardiac pathology was limited to the aortic valve in 12 patients; mortality in this subset was zero. There has been no significant early or late postoperative valvular insufficiency in the 59 surviving patients. More rapid left ventricular mass reduction was seen in this group with a 26% mean reduction within 1 year. A mean follow-up of 32 months in the root replacement group has seen no homograft-related reoperations. CONCLUSIONS: Although the lack of early mortality in the intraaortic group makes this technique appealing, the high incidence of early insufficiency with the realistic expectation of progression has led to our abandonment of the intraaortic technique. Homograft aortic root replacement confers a higher mortality based on the severity of aortic pathology, but offers excellent long-term hemodynamics in any patient. We have expanded our indication for homograft root replacement to include patients with isolated valvular disease rather than reserving it for those patients with extensive root pathology.

Adult↗
PubMed1996

IL-6 antisense-mediated growth inhibition of a choriocarcinoma cell line: an intracellular autocrine growth mechanism.

The growth of tumor cells can be regulated by a variety of cytokines. To investigate the pathogenesis of choriocarcinoma and explore a new therapeutic approach for the carcinoma, we examined the role of IL-6 in the growth of a human choriocarcinoma cell line (JEG-3). IL-6 was identified in the supernatant of the cell culture medium by enzyme-linked immunosorbent assay, indicating that this cell secreted IL-6. The mRNAs of IL-6, IL-6 receptor and gP130, the IL-6 signal transducer, in this cell were shown to be present by reverse transcriptase polymerase chain reaction assay and confirmed by Southern blot hybridization and direct sequencing. The addition of hrIL-6 to the cell culture failed to stimulate cell growth. Monoclonal antibodies against IL-6, IL-6 receptor, and gP130 were also unable to inhibit the proliferation of this cell line. The antisense oligonucleotides targeting IL-6 mRNA, however, inhibited both cell growth and IL-6 production. Taken together, these findings indicate that endogenous IL-6 plays an important role in the growth of the JEG-3 cell line, and it exerts its action by an intracellular autocrine growth mechanism. The results also suggest that the therapeutic trials with monoclonal antibodies designed to neutralize IL-6 or block its receptor will likely fail, whereas the antisense oligonucleotides targeted to IL-6 mRNA may have some value for the treatment of choriocarcinoma and other cancers with intracellular autocrine growth fashion mediated by IL-6.

Antibodies, Monoclonal↗
PubMed1996

Arachidonic acid release: an in vitro alternative for dermal irritancy testing.

Validated in vitro alternatives are being utilized extensively for mutagenicity and ocular irritancy testing. However, validation of alternative assays for dermal irritancy is progressing more slowly. As the irritant response in human skin is mediated, at least in part, by eicosanoids derived from arachidonic acid, the effect of relatively pure anionic surfactants (AS, n=8) and surfactant-containing finished products (FP, n=25) on the release of [3H]arachidonic acid from a prelabelled murine fibroblast cell line (C3H-10T1/2 cells) in vitro was examined. Test substances were administered at various non-lethal concentrations, in triplicate, to 12- and 24-well plates containing preconfluent monolayers (80-90% confluence) of C3H-10T1/2 cells. Because it is impossible to test all concentrations of each test substance in a single assay, statistical techniques were developed to 'standardize' in vitro assay results. In each assay, radiolabel release due to a positive control was also measured, using 0.04, 0.05 and 0.06 mM concentrations of sodium dodecyl sulfate (SDS). Test substance releases were then transformed into 'SDS equivalent' responses, significantly reducing both inter- and intra-assay variability. A straight line was fitted to the test substance responses and compared with that for SDS to calculate the relative potency in vitro for individual AS and FP. Relative potencies correlated with in vivo responses, that is primary dermal irritation indices obtained in rabbits, with Spearman p=0.408 (P<0.03) for 32 tested agents, and p=0.976 (P<0.001) for the eight AS. Exclusion of extremely alkaline or acidic FP (pH>11 or <2, n=4) and those which were insoluble in the aqueous cell culture media at the 1% stock dilution (n=5), improved the overall in vivo-in vitro correlation significantly (p=0.683, P<0.001, n=23) and produced a significant correlation for FP alone (p=0.539, P<0.05, n=15). These results suggest that release of [3H]arachidonic acid from cultured skin cells represents a novel, mechanistically based in vitro screen for dermal irritancy testing.

Animal Testing Alternatives↗
PubMed1996

Synthesis and bronchodilatory activity of four new derivatives of deoxyvasicine.

As part of a continuing effort aimed at the development of efficacious antihistaminic and bronchodilator agents for the treatment of asthma and related respiratory diseases, a series of novel trisubstituted deoxyvasicine derivatives was designed and synthesized. Bronchodilatory activity of pure samples of ligands 17a-d, and DL-8-chlorovasicine hydrochloride is investigated and compared with isoprenaline and aminophylline. These studies confirm the activity of ligands 17a-d and the potentiating effect of 17c on aminophylline.

Alkaloids↗
PubMed1993

Early experience with homograft aortic root replacement for complex aortic pathology.

BACKGROUND: Complex aortic valve and root pathology presents a serious operative challenge. METHODS: During the last 45 months 21 cryopreserved homograft root replacements have been performed in 19 patients. The ages of the patients ranged from 28 to 77 years; there were 15 men and four women. Six patients had endocarditis, four prosthetic and two native valve endocarditis. One patient underwent homograft aortic root replacement twice; one underwent concomitant homograft right ventricular outflow tract reconstruction for pulmonic endocarditis. Causes of aortic pathology in the other 13 patients included ascending aortic aneurysm with valvular regurgitation in seven, Marfan syndrome in two, and four aortic dissections with aortic regurgitation. Ten of the nineteen patients were undergoing reoperative procedures. RESULTS: There were three hospital deaths and one death at home of unknown cause. Two of the three patients who died in hospital had undergone redo cardiac procedures. Dramatic functional class improvement was seen in all survivors. CONCLUSIONS: Follow-up from 2 to 45 months in the fifteen survivors revealed no clinical or significant echocardiographic evidence of valvular regurgitation or recurrent infection. We believe homograft root replacement provides an excellent method of reconstruction with several advantages unique to human valved conduits, including ease of handling, lack of synthetic nidus for recurrent infection, and absence of thrombogenic materials. Homografts should be considered the approach of choice in complex valvular and root infectious processes.

Adult↗
PubMed1992

Prognostic value of dipyridamole thallium-201 scintigraphy in patients with stable chest pain.

The usefulness of dipyridamole testing with planar thallium-201 scintigraphy for assessing risk of subsequent cardiac events was evaluated in 373 patients with stable chest pain. Follow-up information was complete in 362 patients (mean age 64 +/- 9 years). During an average follow-up period of 18 months, cardiac events occurred in 59 patients--unstable angina in 27, nonfatal acute myocardial infarction in 11, and death from cardiac causes in 21. A history of previous myocardial infarction, congestive heart failure, or coronary bypass surgery before the study, or the presence of an abnormal scan or one with a fixed perfusion defect was associated with a significantly increased frequency of subsequent cardiac events (p less than 0.05). However, the presence of a reversible perfusion defect was not associated with increased risk (p = 0.1872). Stepwise logistic regression showed that a history of coronary artery bypass surgery before the study and the presence of a fixed perfusion defect were the only variables with independent predictive value for occurrence of a subsequent cardiac event (p less than 0.05). Survival analysis revealed a significantly increased cardiac event rate in patients with abnormal scans compared with those with normal scans over a 30-month follow-up period (p less than 0.01). We conclude that dipyridamole testing with thallium-201 scintigraphy can provide prognostic information concerning risk of future cardiac events in patients with stable chest pain. The presence of a fixed perfusion defect in particular identifies patients at increased risk.

Angina Pectoris↗
PubMed1989

Effect of exercise level on the ability of thallium-201 tomographic imaging in detecting coronary artery disease: analysis of 461 patients.

This study examined the effect of the level of exercise on the ability of thallium-201 imaging with single photon emission computed tomography (SPECT) to detect coronary artery disease. Patients in group 1 (n = 164) achieved adequate exercise end points, defined as positive exercise electrocardiograms or greater than or equal to 85% of maximal predicted heart rate. Patients in group 2 (n = 108) had submaximal exercise. The SPECT thallium-201 images showed perfusion defects in 74%, 88%, and 98%, respectively, of patients with one, two and three vessel coronary artery disease in group 1, compared with 52%, 84% and 79%, respectively, of such patients in group 2 (p less than 0.05). Perfusion defects showed partial or complete redistribution consistent with ischemia in 56%, 80% and 88%, respectively, of patients with one, two and three vessel coronary artery disease in group 1 compared with 35%, 58% and 56%, respectively, of such patients in group 2 (p = 0.08, less than 0.03 and less than 0.001, respectively). Of 58 patients with normal coronary angiograms or less than 50% diameter stenosis, 36 (62%) had normal SPECT images. In a separate group of 131 patients with less than 5% pretest probability of coronary artery disease, the specificity was 93%. The sensitivity of exercise SPECT imaging in group 1 was higher than that of ST segment depression (p less than 0.001). Thus, the level of exercise affects the results of SPECT thallium imaging in the localization and evaluation of the extent of coronary artery disease and the detection of ischemia.

Coronary Angiography↗
PubMed1989

Use of technetium-99m isonitrile (RP-30A) in assessing left ventricular perfusion and function at rest and during exercise in coronary artery disease, and comparison with coronary arteriography and exercise thallium-201 SPECT imaging.

This study compared the results of stress and rest single-photon emission computed tomography imaging of myocardial perfusion using technetium-99m isonitrile (RP-30A) with the results of stress and redistribution tomographic thallium imaging and the results of coronary arteriography in 39 patients, 11 without and 28 with coronary artery disease (CAD). Each patient underwent 2 exercise studies at identical workload, heart rate and double product. In a subset of 13 patients, concomitant evaluation of left ventricular (LV) function using first-pass radionuclide angiography with a multi-crystal camera also was performed with bolus injections of isonitrile. Isonitrile had similar sensitivity (82 vs 82%, difference not significant), a slightly--but not significantly--higher specificity (100 vs 82%) and similar predictive accuracy (87 vs 82%) to thallium-201. The tracer uptake was assessed in 20 segments/study. There was concordance between the isonitrile and thallium-201 images in 723 of the 780 segments (93%) (kappa = 0.83 +/- 0.02). In general, the isonitrile images were considered of better quality than the thallium-201 images. All 10 patients with CAD who underwent concomitant first-pass radionuclide angiography had either perfusion abnormalities or an abnormal ejection fraction response to exercise. Thus, technetium-99m isonitrile provides a reliable method of assessment of CAD with a sensitivity, specificity and predictive accuracy comparable to that of exercise thallium-201 imaging. Additional advantages include better image quality and the ability to obtain concomitant assessment of LV function with the use of first-pass radionuclide angiography.

Angiography↗