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Biomedical subjects

W Lee

Publications and source records attributed to W Lee.

At least 109 records · Page 6Linked to original sources
PubMed2000

Direct liquid chromatographic enantiomer separation of new fluoroquinolones including gemifloxacin.

The enantiomers of gemifloxacin mesylate (formerly LB20304a), a new fluoroquinolone compound with potent in vitro and in vivo antibacterial profile were resolved on a commercially available Crownpak CR chiral stationary phase (CSP). All of the fluoroquinolones, including gemifloxacin used in this study, were well enantioseparated on Crownpak CR(+) column. These results are the first reported for the direct separation of the enantiomers of quinolones on chiral crown ether coated Crownpak CR CSP. The behavior of chromatographic parameters by the change of mobile phase additives for the resolution of gemifloxacin was investigated. Also, the effect of structural change of gemifloxacin on chiral recognition was described.

Anti-Infective Agents↗
PubMed2000

Association of carboxyl esterase with facilitative glucose transporter isoform 4 (GLUT4) intracellular compartments in rat adipocytes and its possible role in insulin-induced GLUT4 recruitment.

Facilitative glucose transporter isoform 4 (GLUT4) in rat adipocytes is largely sequestered in intracellular sites, and insulin recruits GLUT4 from these sites to the cell surface. The process is known to involve multiple intracellular compartments and associated proteins, many of which are yet to be identified. Recently, we purified three distinct insulin-sensitive intracellular GLUT4 compartments (G4T(L), G4H, and G4L) in rat adipocytes and unraveled several new resident proteins in these compartments. Here, we describe one of them, a 62-kDa protein, purified and identified as rat adipose tissue carboxyl esterase (p62/CE) by matrix-assisted laser desorption/ionization time of flight mass spectroscopy, reverse transcription-polymerase chain reaction, gene cloning, and immunological and enzymatic activity measurements. p62/CE in rat adipocytes was 80% cytosolic and 20% microsome-associated. It was found in all of the three insulin-sensitive intracellular GLUT4 compartments, and particularly enriched in G4T(L,) a compartment thought to represent GLUT4 endocytic vesicles. Significantly, an antibody against p62/CE introduced into rat adipocytes completely abolished the insulin-induced GLUT4 recruitment to the plasma membrane in host cells without affecting the basal GLUT4 distribution. Together, these findings suggest that p62/CE plays a key role in insulin-induced GLUT4 recruitment in rat adipocytes, probably by hydrolyzing acylglycerols or acyl-CoA esters to the respective free acids that are required for GLUT4 transport vesicle budding and/or fusion.

Adipocytes↗
PubMed2000

A light-inactivated antibiotic.

Sodium 7beta-[(R)-2-(N(b)()-o-nitrobenzyloxycarbonyl)hydrazino-3-pheny lpropa namido]cephalosporanate (1) is described as a new type of beta-lactam antibiotic, which undergoes light-induced destruction of its beta-lactam moiety and hence becomes biologically inactive. This type of antibiotic holds the promise of self-destruction over a number of hours of exposure to light, so that it would not allow selection of resistance in the environment.

Bacteria↗
PubMed2000

Determination and excretion study of gestrinone in human urine by high performance liquid chromatography and gas chromatography/mass spectrometry.

Gestrinone was studied by HPLC for screening and by GC/MS for confirmation. Three unknown peaks were found by HPLC which are probably the metabolites of gestrinone, and conjugated gestrinone in dosed human urine. The metabolites and gestrinone were excreted as the conjugated forms. The total amounts of metabolite 1 and conjugated gestrinone, recovered after 48 h, were 0.20 and 0.32 mg, respectively. When metabolite 1 was tested by LC/MS and LC/MS/MS, the parent ion was m/z 327, [MH](+), and fragment ions were seen at m/z 309 [MH - H(2)O](+), 291 [MH - 2H(2)O](+), 283, 263 and 239. The TMS-enol-TMS ether derivative of gestrinone has three peaks in the GC/MS chromatogram formed by tautomerism. The reproducibility of the derivatization method was stable and recoveries were over 87% when spiked into blank urine.

Chromatography, Liquid↗
PubMed2000

Determination of the metabolites of gestrinone in human urine by high performance liquid chromatography, liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry.

Gestrinone was studied by high performance liquid chromatography (HPLC) for screening and by gas chromatography/mass spectrometry (GC/MS) for confirmation. When the chromatograms of blank, spiked urine and dosed urine were compared by HPLC, two unknown metabolites were found and these were excreted as the conjugated forms. Metabolites 1 and 2 were tested by LC/MS and LC/MS/MS and both had parent ions at m/z 325. The fragment ion of metabolite 1 was at m/z 263 and ions for metabolite 2 were m/z 307 [MH - H(2)O](+), 289, 279 and 241. LC/MS/MS of m/z 263 as the parent ion of metabolite 1 gave fragment ions at m/z 245 and 217, which were assumed to be [263 - H(2)O](+) and [235 - H(2)O](+), respectively. The trimethylsilyl (TMS)-enol-TMS ether derivative of gestrinone displayed three peaks in its GC/MS chromatogram, formed by tautomerism.

Adult↗
PubMed2000

Angiogenesis in the mouse lung.

When pulmonary arterial blood flow is obstructed in all mammals studied, there is a compensatory growth of the bronchial vasculature. This angiogenesis normally occurs through a proliferation of the systemic circulation to the intraparenchymal airways. It is an important pathophysiological process, not only in pulmonary vascular disease, but also in lung cancer, because the blood flow that supplies primary lung tumors arises from the systemic circulation. In the mouse, however, the systemic blood vessels that supply the trachea and mainstem bronchi do not penetrate into the intraparenchymal airways, as they do in all other larger species. In this study, we attempted to generate a new functional bronchial circulation in the mouse by permanently obstructing 40% of the pulmonary circulation. We quantified the systemic blood flow to the lung with fluorescent microspheres for 3 months after left pulmonary artery ligation. Results demonstrated that a substantial systemic blood flow to the lung that can eventually supply up to 15% of the normal pulmonary flow can be generated beginning 5-6 days after ligation. These new angiogenic vessels do not arise from the extraparenchymal bronchial circulation. Rather they enter the lung directly via a totally new vasculature that develops between the visceral and parietal pleuras, supplied by several intercostal arteries. This unique model of angiogenesis occurs in the absence of any hypoxic stimulus and mimics the vascular source of many lung tumors.

Airway Resistance↗
PubMed2000

Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome.

OBJECTIVE: To describe the prenatal ultrasonographic diagnosis, natural evolution, and clinical outcomes of vasa previa in a large population at a single institution. METHODS: We attempted to view the internal cervical os of 93,874 women with second- and third-trimester pregnancies during an 8-year period. Echogenic parallel or circular lines near the cervix, seen by gray-scale ultrasonography, raised the possibility of vasa previa. Diagnosis was confirmed by Doppler and endovaginal studies if aberrant vessels over the internal cervical os were suspected. Abnormal placental morphology and velamentous cord insertion were documented if they were identified during prenatal scans. Ultrasonographic findings were correlated with clinical courses, perinatal outcomes, and placental pathology examinations. RESULTS: Eighteen cases of vasa previa were suspected at a mean (+/- standard deviation) gestational age of 26.0 +/- 6.3 weeks; the earliest diagnosis was at 15.6 weeks' gestation. Eight of those cases initially showed placental edge over the internal os and later developed vasa previa after the placenta "receded" from the cervix. Six women had mild vaginal bleeding at a mean gestational age of 31.3 weeks. Three women had normal late third-trimester scans and were allowed to have uncomplicated vaginal deliveries. The remaining subjects delivered by cesarean. There were two deaths (one fetal and one neonatal), and minor preterm complications slightly prolonged infant hospitalizations. One set of preterm twins needed neonatal transfusions. Pathology findings included ten cases of velamentous insertion and three cases each of bilobed placentas, succenturiate lobes, and marginal cord insertion. CONCLUSION: Vasa previa was detected in asymptomatic women as early as the second trimester. Perinatal outcome was generally favorable, although several infants had slightly extended newborn nursery admissions due to mild complications of prematurity.

Female↗
PubMed2000

Characterization of PCB-degrading bacteria immobilized in polyurethane foam.

This study is carried out to investigate (1) conditions for the synthesis of polyurethane foam to be used for immobilizing microorganisms, (2) the viability of microorganisms immobilized simultaneously into the pores of a polyurethane foam when the foam is synthesized, and (3) the difference in the ability to degrade PCBs between the immobilized and suspended microorganisms. The results of this study show that polyurethane foam is suitable for synthesizing 10% NCO-prepolymer, water and surfactant in the ratio of 100:2.6:1.2 (w/w), respectively, and the viability of microorganisms (input microbes) immobilized in the foam is high. The input microbes, designated as strain SY5, are isolated from a municipal sewage treatment plant. In addition, immobilized strain SY5 degrades 5-40% more PCB of a PCB mixture (Aroclor 1242) than the suspended strain SY5.

Journal Article↗
PubMed2000

Bradyzide, a potent non-peptide B(2) bradykinin receptor antagonist with long-lasting oral activity in animal models of inflammatory hyperalgesia.

Bradyzide is from a novel class of rodent-selective non-peptide B(2) bradykinin antagonists (1-(2-Nitrophenyl)thiosemicarbazides). Bradyzide has high affinity for the rodent B(2) receptor, displacing [(3)H]-bradykinin binding in NG108-15 cells and in Cos-7 cells expressing the rat receptor with K(I) values of 0.51+/-0.18 nM (n=3) and 0.89+/-0.27 nM (n=3), respectively. Bradyzide is a competitive antagonist, inhibiting B(2) receptor-induced (45)Ca efflux from NG108-15 cells with a pK(B) of 8.0+/-0.16 (n=5) and a Schild slope of 1.05. In the rat spinal cord and tail preparation, bradyzide inhibits bradykinin-induced ventral root depolarizations (IC(50) value; 1.6+/-0.05 nM (n=3)). Bradyzide is much less potent at the human than at the rodent B(2) receptor, displacing [(3)H]-bradykinin binding in human fibroblasts and in Cos-7 cells expressing the human B(2) receptor with K(I) values of 393+/-90 nM (n=3) and 772+/-144 nM (n=3), respectively. Bradyzide inhibits bradykinin-induced [(3)H]-inositol trisphosphate (IP(3)) formation with IC(50) values of 11.6+/-1.4 nM (n=3) at the rat and 2.4+/-0.3 microM (n=3) at the human receptor. Bradyzide does not interact with a range of other receptors, including human and rat B(1) bradykinin receptors. Bradyzide is orally available and blocks bradykinin-induced hypotension and plasma extravasation. Bradyzide shows long-lasting oral activity in rodent models of inflammatory hyperalgesia, reversing Freund's complete adjuvant (FCA)-induced mechanical hyperalgesia in the rat knee joint (ED(50), 0.84 micromol kg(-1); duration of action >4 h). It is equipotent with morphine and diclofenac, and 1000 times more potent than paracetamol, its maximal effect exceeding that of the non-steroidal anti-inflammatory drugs (NSAIDs). Bradyzide does not exhibit tolerance when administered over 6 days. In summary, bradyzide is a potent, orally active, antagonist of the B(2) bradykinin receptor, with selectivity for the rodent over the human receptor. British Journal of Pharmacology (2000) 129, 77 - 86

Administration, Oral↗
PubMed2000

Interleukin-18 and the costimulatory molecule B7-1 have a synergistic anti-tumor effect on murine melanoma; implication of combined immunotherapy for poorly immunogenic malignancy.

Interleukin-18 has been described recently as a cytokine secreted primarily by Kupffer cells. Furthermore, it has been shown that it has significant anti-tumor effects, which are mediated by T cells and natural killer cells, in a manner similar to interleukin-12. Here, we report the evaluation of the effects of the systemic administration of interleukin-18 in combination with B7-1 (CD80) expressed on tumor cells [interleukin-18 + B7-1] on the growth of murine B16 melanoma in vivo. After the subcutaneous inoculation of B16 melanoma, B16 tumors grew progressively in immunocompetent syngeneic C57BL/6 mice. Mice treated with either interleukin-18 or immunized with B7-1-transduced B16 did not demonstrate significant anti-tumor effect. The combination of the two treatments, however, resulted in dramatic suppression of melanoma formation, tumor growth, and a significant improvement in survival. Inhibitory effects of [interleukin-18 + B7-1] on lung metastasis in mice were also detected. Additionally, mice treated with [interleukin-18 + B7-1] showed an increase of natural killer cytotoxicity and interferon-gamma production in vivo. Unlike [interleukin-18 + B7-1], [interleukin-12 + B7-1] did not have a strong anti-tumor effect against B16 melanoma. Histologic characterization after the [interleukin-18 + B7-1] treatment confirmed the infiltration of natural killer cells into the tumor, suggesting that natural killer cells may be involved in the [interleukin-18 + B7-1]-induced anti-tumor effect. This finding was confirmed by showing that depletion of NK1.1+ cells before immunization inhibits the [interleukin-18 + B7-1]-induced anti-tumor effect. Depletion of CD3+ cells in vivo also decreased the anti-tumor effect of [interleukin-18 + B7-1], suggesting the importance of CD3+ T cells. Collectively, combination with interleukin-18 and B7-1 expression has synergistic anti-tumor effects against B16 murine melanoma.

Animals↗
PubMed2000

Fetal cleft lip and palate detection by three-dimensional ultrasonography.

OBJECTIVES: To demonstrate a standardized approach for the evaluation of cleft lip and palate by three-dimensional (3D) ultrasonography. DESIGN: This was a retrospective study of seven fetuses with confirmed facial cleft anomalies. Post-natal findings were compared to a blinded review of 3D volume data from abnormal fetuses with seven other normal fetuses that were matched for gestational age. Upper lip integrity was examined by 3D multiplanar imaging. Sequential axial views were used to evaluate the maxillary tooth-bearing alveolar ridge contour and anterior tooth socket alignment. Alveolar ridge disruption suggested cleft palate. Premaxillary protrusion, either by multiplanar imaging or surface rendering, indicated bilateral cleft lip and palate. RESULTS: Post-natal findings confirmed bilateral cleft lip and palate (four cases), unilateral cleft lip and palate (one case), and unilateral cleft lip (two cases). Multiplanar review identified all three fetuses with unilateral cleft lip, three of four fetuses with bilateral cleft lip, one fetus with unilateral cleft palate, and three of four fetuses with bilateral cleft palate. Surface rendering correctly identified all cleft lips, with the exception of one fetus, who was thought to have a unilateral cleft lip and palate, despite the actual presence of a bilateral lesion. One cleft palate defect was directly visualized by 3D surface rendering. No false-positives occurred. CONCLUSION: Interactive review of standardized 3D multiplanar images allows one to evaluate labial defects, abnormalities of the maxillary tooth-bearing alveolar ridge, and presence of premaxillary protrusion for detecting cleft lip and palate anomalies. Surface rendering may increase diagnostic confidence for normal or abnormal studies. This technology provides an array of visualization tools that may improve the prenatal characterization of facial clefts, particularly of the palate.

Cleft Lip↗
PubMed2000

Vasa previa: prenatal detection by three-dimensional ultrasonography.

OBJECTIVE: To describe three-dimensional (3D) ultrasonography (US) for the antepartum diagnosis of vasa previa. DESIGN: This was a descriptive study of two pregnant women who were suspected to have vasa previa by conventional gray-scale ultrasonography. Three-dimensional studies were also performed during the early third trimester to further investigate the possibility of this condition. RESULTS: In the first case, 3D US provided gray-scale multiplanar and surface-rendered views of an aberrant vessel over the internal cervical os. For the second case, a 'flight-path' technique allowed the examiner to follow axial views of the endocervical canal toward the internal os until an aberrant vessel was verified. The 'niche-mode' analysis, with and without color power Doppler ultrasonography, was also used to confirm the diagnosis. CONCLUSION: Three-dimensional ultrasonography offers several additional imaging tools that are not currently provided by more conventional ultrasonography for the detection of vasa previa. It represents an important adjunct to two-dimensional (2D) studies, especially when this diagnosis is questionable.

Adult↗
PubMed2000

MR imaging of changes of the growth plate after partial physeal removal and fat graft interposition in rabbits.

RATIONALE AND OBJECTIVES: The most important complication of skeletal injuries involving the growth plate is growth disturbance. The purpose of this study was to evaluate MR features of growth plate modification after fat graft interposition in growth plate injury and to correlate these findings with pathological findings. METHODS: A growth plate injury model was used in 12 skeletally immature rabbits. A longitudinal drill hole 5 mm in diameter was created in the central part of the growth plate in the distal femur, bilaterally. One side was filled with autologous fat, and the contralateral defect was left empty as a control. Magnetic resonance imaging was obtained 1, 3, and 6 months after surgery, and routine histological study was performed. The authors evaluated sequential changes in MR images and the histological basis of MR findings. RESULTS: In grafted femur, the signal intensity of the grafted area was lower than that of the surrounding bone on T2-weighted images at 1 month. The growth plate defect at 3 to 6 months was modified and had a proximally tapering appearance. The ratio of the growth plate defect was smaller in the grafted femur than in the control femur after surgery. Histologically, the fat-grafted area was replaced by fibrous connective tissue. In the control femur, a bony bridge was rectangular in the longitudinal direction and showed isosignal intensity with a rim of low signal intensity on T1-weighted imaging. Histologically, the defect was filled with mature fatty marrow with new bone formation in the control femur. CONCLUSIONS: The proximally pointing appearance and the low signal intensity of the grafted area on MR suggested fibrous degeneration of grafted fat that prevented solid bony bridge formation in experimentally induced growth plate injury.

Adipose Tissue↗
PubMed2000

The active site and substrates binding mode of malonyl-CoA synthetase determined by transferred nuclear Overhauser effect spectroscopy, site-directed mutagenesis, and comparative modeling studies.

The active sites and substrate bindings of Rhizobium trifolii molonyl-CoA synthetase (MCS) catalyzing the malonyl-CoA formation from malonate and CoA have been determined based on NMR spectroscopy, site-directed mutagenesis, and comparative modeling methods. The MCS-bound conformation of malonyl-CoA was determined from two-dimensional-transferred nuclear Overhauser effect spectroscopy data. MCS protein folds into two structural domains and consists of 16 alpha-helices, 24 beta-strands, and several long loops. The core active site was determined as a wide cleft close to the end of the small C-terminal domain. The catalytic substrate malonate is placed between ATP and His206 in the MCS enzyme, supporting His206 in its catalytic role as it generates reaction intermediate, malonyl-AMP. These findings are strongly supported by previous biochemical data, as well as by the site-directed mutagenesis data reported here. This structure reveals the biochemical role as well as the substrate specificity that conservative residues of adenylate-forming enzymes have.

Adenosine Triphosphate↗
PubMed2000

Interpretation of Wada memory test for lateralization of seizure focus by use of (99m)technetium-HMPAO SPECT.

PURPOSE: Although the intracarotid amobarbital procedure (IAP) or Wada test is useful in lateralizing seizure focus in patients with temporal lobe epilepsy (TLE), the results of the IAP memory test are frequently nonlateralizing. An insufficient suppression of the medial temporal region contralateral to the seizure focus may contribute to the failure of lateralization. We tried to correlate IAP memory results with the functional changes in the contralateral medial temporal region as measured by single photon emission computed tomography (SPECT) during IAP. METHODS: We performed a (99m)technetium-(Tc) hexamethylene-propylene-amine-oxime (HMPAO) brain SPECT in 19 medial TLE patients during a contralateral IAP (sodium amobarbital injected contralateral to the seizure focus). Regional cerebral blood flow (rCBF) was measured in the contralateral medial temporal region. The amount of decrease in the rCBF was calculated by subtracting the previous measurement from the one obtained with the interictal SPECT. RESULTS: Ten (53%) patients passed and nine (47%) failed the contralateral IAP. The mean percentage decrease in rCBF was 5.3+/-5.3%. There was a significant negative correlation between a decrease in the rCBF and the IAP memory-retention score by Spearman correlation (p = -0.53: p<0.021). Patients with smaller decreases in rCBF (<5%) more frequently passed the contralateral IAP memory test than did those with larger decreases (80 vs. 22%; p<0.023). CONCLUSIONS: We suggest that an insufficient suppression of the contralateral medial temporal function is partly responsible for nonlateralizing IAP memory tests. An IAP-SPECT may be useful in interpreting IAP memory tests for the lateralization of seizure focus in TLE patients.

Adult↗