Biomedical subjects

Y C Lee

Publications and source records attributed to Y C Lee.

At least 55 records · Page 3Linked to original sources

PubMed2001

Fluorometric determination of EDTA and EGTA using terbium-salicylate complex.

A method for determining EDTA (ethylenediaminetetraacetic acid) based on a highly fluorescent terbium-EDTA-salicylic acid complex formation was developed. EDTA from as low as a few picomoles to as high as several nanomoles can be determined in a microtiter plate in 10-20 min. Ethyleneglycol-bis(2-aminoethoxy)-tetraacetic acid (EGTA) also can be determined by the same method, but its sensitivity is ca. 14-fold lower. Interestingly, diethylenetriamine tetraacetic acid did not form fluorescent complex with terbium under the same conditions.

Calcium↗

PubMed2001

Isolation and characterization of major glycoproteins of pigeon egg white: ubiquitous presence of unique N-glycans containing Galalpha1-4Gal.

Ovotransferrin (POT), two ovalbumins (POA(hi) and POA(lo)), and ovomucoid (POM) were isolated from pigeon egg white (PEW). Unlike their chicken egg white counterparts, PEW glycoproteins contain terminal Galalpha1-4Gal, as evidenced by GS-I lectin (specific for terminal alpha-Gal), anti-P(1) (Galalpha1-4Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glcbeta1-1Cer) monoclonal antibody, and P fimbriae on uropathogenic Escherichia coli (specific for Galalpha1-4Gal). Galalpha1-4Gal on PEW glycoproteins were found in N-glycans releasable by treatment with glycoamidase F. The respective contents of N-glycans in each glycoprotein were 3.5%, POT; 17%, POA(hi); and 31-37%, POM. POA(hi) has four N-glycosylation sites, in contrast to chicken ovalbumin, which has only one. High performance liquid chromatography analysis showed that N-glycans on POA(hi) were highly heterogeneous. Mass spectrometric analysis revealed that the major N-glycans were monosialylated tri-, tetra-, and penta-antennary oligosaccharides containing terminal Galalpha1-4Gal with or without bisecting N-acetylglucosamine. Oligosaccharide chains terminating in Galalpha1-4Gal are rare among N-glycans from the mammals and avians that have been studied, and our finding is the first predominant presence of (Galalpha1-4Gal)-terminated N-glycans.

Animals↗

PubMed2001

N-glycan structures from the major glycoproteins of pigeon egg white: predominance of terminal Galalpha(1)Gal.

N-Glycans from major glycoproteins of pigeon egg white (ovotransferrin, ovomucoid, and ovalbumins) were enzymatically released and were reductively aminated with 2-aminopyridine, separated, and structurally characterized by mass spectrometry and a three-dimensional mapping technique using three different columns of high performance liquid chromatography (HPLC) (Takahashi, N., Nakagawa, H., Fujikawa, K., Kawamura, Y., and Tomiya, N. (1995) Anal. Biochem. 226, 139-146). Twenty-five major N-glycan structures, all of them hitherto unknown, were identified as pyridylamino derivatives. Of these, 13 were neutral, 10 were monosialyl, and 2 were disialyl oligosaccharides. All N-glycans contain from one to four Galalpha(1,4)Galbeta(1,4) sequences at the nonreducing terminal positions and are devoid of fucose residues. N-Acetylneuraminic acids were alpha(2,6)-linked only to beta-galactose. The HPLC profiles of the N-glycans from four different glycoproteins were qualitatively very similar to each other, but not identical in the peak distributions. Monosialyl glycans were most abundant in all four glycoproteins, followed by neutral glycans. Disialyl glycans were lowest in ovotransferrin, and highest in ovomucoid. Triantennary structures with bisecting GlcNAc were predominant in ovotransferrin, and tetra-antennary (with and without bisecting GlcNAc-containing) structures were predominant in other glycoproteins. Penta-antennary structures (with a sialic acid and without bisecting GlcNAc residue) were also found in small quantities in all four glycoproteins. In contrast to the chicken egg white counterparts, which contain mostly high mannose and hybrid types, all N-glycan structures in the major pigeon egg white glycoproteins are complex type.

Aminopyridines↗

PubMed2001

Comparison of chemical and enzymatic synthesis of 2-acetamido-2-deoxy-D-mannose 6-phosphate: a new approach.

Chemical and enzymatic methods to synthesis of 2-acetamido-2-deoxy-D-mannose-6-phosphate (ManNAc-6-P) have been investigated. A new preparative method has been developed although some established procedures were tried. In this new method, a 6-O-acetyl or 4,6-di-O-acetyl group of the per-O-acetylated 2-acetamido-2-deoxy-D-mannose (ManNAc) were regioselectively removed with an esterase from the yellow yeast, Rhodosporidium toruloides, followed by phosphorylation and O-deacetylation under mild conditions. 1H and 13C NMR data spectra of ManNAc-6-P were recorded.

Acetylation↗

PubMed2001

Vascular endothelial growth factor 189 mRNA isoform expression specifically correlates with tumor angiogenesis, patient survival, and postoperative relapse in non-small-cell lung cancer.

PURPOSE: The purpose of this study was to evaluate the correlation between the expression of four different vascular endothelial growth factor (VEGF) mRNA isoforms (VEGF121, VEGF165, VEGF 189, and VEGF206) and the clinicopathologic characteristics, tumor angiogenesis, and outcome of patients with non-small-cell lung cancer. PATIENTS AND METHODS: We examined the expression of four different VEGF mRNA isoforms in 57 non-small-cell lung cancers using reverse transcriptase polymerase chain reaction and the tumor angiogenesis using immunohistochemical staining. RESULTS: All 57 lung cancer samples expressed the VEGF121, VEGF165, and VEGF189 mRNA isoforms, and three expressed the VEGF206 mRNA isoform. A high tumoral VEGF189 mRNA isoform expression ratio was associated with a high intratumoral microvessel count (P = .013), short survival (< 24 months; P = .001), and early postoperative relapse (< 12 months; P = .001). Survival and postoperative relapse time were significantly shorter in patients with a high compared with a low tumor VEGF189 mRNA isoform expression ratio (P = .0001 and P = .0086, respectively, log-rank test). In contrast, the VEGF165 and VEGF 206 mRNA isoform expression ratios showed no statistical correlation with tumor angiogenesis, postoperative relapse time, or survival. A high VEGF121 mRNA isoform expression ratio was associated with short survival (< 24 months) and early relapse (< 12 months). Multivariate analysis showed that VEGF 189 mRNA isoform expression, microvessel count, and nodal status were the most important independent prognostic factors for patient survival and postoperation recurrence. CONCLUSION: The VEGF189 mRNA isoform expression ratio shows a greater correlation with tumor angiogenesis, postoperative relapse time, and survival than do the expression ratios for the VEGF121, VEGF165, and VEGF206 mRNA isoforms and can be used as a prognostic indicator for patients with non-small-cell lung cancers.

Carcinoma, Non-Small-Cell Lung↗

PubMed2001

Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs.

BACKGROUND: Diffuse pleural thickening and pleural plaques are the commonest radiological manifestations of asbestos exposure. Differentiation between subpleural fat and non-calcified pleural plaques is important clinically and medico-legally. This study aims to determine if apparent circumscribed pleural thickening on chest radiographs is related with obesity. METHODS: Surveillance chest x-rays of 693 former asbestos workers were read with the ILO classification. Subjects with costophrenic angle obliteration (n = 57) were analyzed separately. The remaining subjects were subdivided according to their body mass index (BMI): Group 1 < 26 kg/m(2); Group 2 26-30 kg/m(2); Group 3 > 30 kg/m(2). RESULTS: Baseline characteristics, asbestos exposure, and profusion scores were evenly distributed. BMI of > 30 kg/m(2) was associated with a higher prevalence of pleural thickening on CXR (Gp1 = 8.5%; Gp2 = 9.3%; Gp3 = 18.3%). This relationship was strongest in the subgroups with 25-50% of the lateral chest wall involved and pleural thickness of < 10 mm. CONCLUSIONS: Obesity (BMI > 30 kg/m(2)) is related to apparent circumscribed pleural thickening on CXR, especially thin (< 1 cm) shadows covering 25-50% of the lateral chest wall.

Adipose Tissue↗

PubMed2001

NMR conformational analysis of cis and trans proline isomers in the neutrophil chemoattractant, N-acetyl-proline-glycine-proline.

Alkaline hydrolysis of corneal proteins in the alkali-injured eye releases N-acetyl-proline-glycine-proline (Ac-Pro-Gly-Pro-OH) among other peptides. It has been shown that this tripeptide is a neutrophil chemoattractant. Existing data suggest that the release of this peptide is the catalytic event for early neutrophil invasion of the cornea leading to corneal ulcers. In order to design inhibitors of this tripeptide chemoattractant that would block neutrophil invasion and diminish corneal ulcers, we studied the solution properties of this tripeptide by NMR spectroscopy and compared this peptide to Ac-Pro-Gly-OH (a weaker chemoattractant), and to Ac-Pro-OH (inactive). The NMR data were consistent with Ac-Pro-Gly-Pro-OH existing in solution as a mixture of four isomers with different cis and trans conformations about the two X-proline amide bonds. The isomer with two trans conformations (trans-trans) was the most dominant (41%) in aqueous solution. This was followed by the isomers with mixed cis and trans conformations (trans-cis, 26% and cis-trans, 20%). The isomer with two cis conformations (cis-cis) was the least favored (13%). The populations of these isomers were investigated in DMSO and they were similar to those reported in aqueous solutions except that the ordering of the trans-cis and cis-trans isomers were reversed. NMR NH temperature coefficients and nuclear Overhauser effect (NOE) measurements as well as CD spectroscopy were used to demonstrate that the four isomers exist primarily in an extended conformation with little hydrogen bonding. The available (NOE) information was used with molecular dynamics calculations to construct a dominant solution conformation for each isomer of the tripeptide. This information will serve as a model for the design of peptide and nonpeptide inhibitors of the chemoattractant.

Alkalies↗

PubMed2001

Microcystic adnexal carcinoma of the vulva.

BACKGROUND: Microcystic adnexal carcinoma (MAC) is a subset of sweat gland carcinoma first described as a specific entity by D. J. Goldstein, R. J. Barr, and D. J. Santa Cruz (Cancer 1982;50:566-72). We report the first case of MAC occurring on the vulva and review the literature pertaining to this rare tumor. CASE: A 43-year-old multiparous black woman presented initially to Kings County Hospital Medical Center with a chief complaint of a vulvar lesion arising on the left labia majora which she had noted for 4 years prior to presentation. Aside from increasing paresthesia in the area, she denied any constitutional symptoms. Her past medical history was significant only for hyperthyroidism and mild hypertension and surgical history was noncontributory. Gynecologic history was unremarkable, with sporadic care over the last 20 years. Physical examination revealed a 1.5 x 2.0-cm raised, well-circumscribed, firm mobile lesion on the left labia majora. It was noted to be yellow in color with the surrounding tissue being unremarkable in character. The remainder of her gynecologic examination and lymph node survey was unremarkable. Preoperative chest X ray was negative as was the CAT scan of the abdomen and pelvis. All laboratory values were within normal limits. A Pap smear done preoperatively was significant for atypical squamous and glandular cells of undetermined significance. Subsequent colposcopic examination of the cervix was remarkable for cervicitis and was adequate, with the entire transformation zone visualized. Both endocervical curettage and endometrial biopsy were normal. Initially, an excisional biopsy was performed with final pathology demonstrating microcystic adnexal carcinoma with positive surgical margins. She subsequently underwent a left radical hemivulvectomy with bilateral inguinal groin lymph node dissection. At the time of surgery, the left labia majora was noted to be well healed, with a residual surgical scar easily discernible. No areas of discoloration were noted and digital palpation of the area was unremarkable. Microscopic residual tumor was noted; however, all surgical margins and lymph nodes were negative for tumor. Her postoperative course was unremarkable. The patient has continued to do well since the time of her surgery and is being followed conservatively. CONCLUSION: Radical vulvectomy should be performed when MAC occurs in the vulva to secure negative margins of resection. Groin dissection should be reserved for cases in which the inguinal lymph nodes are clinically suspicious or in cases of tumor recurrence.

Adult↗

PubMed2001

Differential distribution of ganglioside GM3 in seminiferous tubule and epididymis of adult rats.

Gangliosides are ubiquitous membrane components in mammalian cells and are suggested to play important roles in various functions such as cell-cell interaction, adhesion, cell differentiation, growth control and signaling. Among all ganglio-series gangliosides, GM3 has the simplest carbohydrate structure, and has been shown as a major ganglioside in male reproductive system. To study GM3 distribution in the seminiferous tubule and epididymis, frozen sections were stained with specific monoclonal antibody (MAb) against ganglioside GM3. In the seminiferous tubule of testis, pachytene spermatocytes and spermatids expressed ganglioside GM3, but not in spermatogonia and sertoli cells. Spermatogonia and sertoli cells near the basement membrane were negatively reacted to anti-GM3. In the epididymis, GM3 was expressed only in some interstitial cells. Taken together, these results suggest that the expression of ganglioside GM3 in rat seminiferous tubule and epididymis is spatio-temporally regulated during spermatogenesis.

Animals↗

PubMed2001

Monoamine oxidase B inhibitors from the fruits of Opuntia ficus-indica var. saboten.

Three varieties of methyl citrate and 1-methyl malate were isolated from the fruits of Opuntia ficus-indica var. saboten Makino through in vitro bioassay-guided isolation for the inhibition on monoamine oxidase(MAO). The IC50 values for MAO-B of 1-monomethyl citrate, 1,3-dimethyl citrate, trimethyl citrate and 1-methyl malate were 0.19, 0.23, 0.61 and 0.25 mM, respectively. However, on MAO-A, their inhibitions showed only marginal activity.

Citric Acid↗

PubMed2001

Transcriptional coregulators of the nuclear receptor superfamily: coactivators and corepressors.

Nuclear receptors, many of which undergo a major conformational change upon binding specific ligand, belong to a superfamily of proteins that bind to specific DNA sequences and control gene transcription. They regulate the assembly of a transcriptional preinitiation complex at the promoter of target genes and modulate their expression in response to ligand. In particular, nuclear receptors repress or stimulate transcription by recruiting corepressor or coactivator proteins, in addition to directly contacting the basal transcription machinery. In this review, we discuss recent progress in studies of these transcriptional coregulators of nuclear receptors.

Acetyltransferases↗

PubMed2001

Seizure outcomes after anterior callosotomy in patients with posterior-dominant and with anterior-dominant epileptiform discharges.

OBJECTS: We wished to find whether there was any difference in the postoperative seizure outcome between patients with bisynchronous anterior-dominant and those with posterior-dominant EDs after anterior callosotomy. METHODS: Seizure outcomes after anterior callosotomy in 7 patients with bisynchronous posterior-dominant epileptiform discharges and in 54 patients with anterior-dominant seizures were compared. All 61 cases had been followed up for more than 2 years after operation. One patient (14.3%) had become seizure free. Two patients (28.6%) had more than 50% reduction in seizure frequency, but 4 patients (57.2%) showed no improvement at all. The percentage of cases with significant improvement (more than 50% reduction of seizure frequency) was 43% (3 in 7), which is lower than in the patients with bisynchronous anterior-dominant EDs (64.8%). CONCLUSIONS: Our preliminary results suggest that anterior partial callosotomy could still be helpful in cases with bisynchronous posterior-dominant epileptiform discharges but the prognosis may be less optimistic than for those with anteriorly located discharges.

Child↗

PubMed2001

Increased expression of iNOS and c-fos via regulation of protein tyrosine phosphorylation and MEK1/ERK2 proteins in terminal bronchiole lesions in the lungs of rats exposed to cigarette smoke.

Epidemiological evidence suggests that smoking is a major cause of human lung cancer. However, the mechanism by which cigarette smoke induces the cancer remains unestablished. To evaluate the effects of cigarette smoke on the expression of inducible nitric oxide synthase (iNOS), nuclear protooncogenes and related mitogen-activated protein kinases (MAPKs) in rat lung tissue, a histopathological study of the effects of gas-phase cigarette smoke on rat lung tissue were carried out. The terminal bronchioles were found to be infiltrated predominantly by lymphocytes in the peribronchiolar region and a mild to moderate degree of emphysema was noted in the alveolar spaces. The terminal bronchioles also showed marked lipid peroxidation, dilatation, and peribronchiolar fibrosis. Immunohistochemical evaluation showed that the expression of iNOS, NF-kappa B, MAPKs (MEK1, ERK2), phosphotyrosine protein and c-fos was increased in the terminal bronchioles but protein kinase C (PKC), MEKK-1, c-jun, p38 and c-myc showed no change. These results provide evidence to suggest that exposure to cigarette smoke results in oxidant stress which leads to the stimulation of iNOS and c-fos together with the induction of protein tyrosine phosphorylation and MEK1/ERK2 which in turn may promote lung pathogenesis.

Animals↗

PubMed2001

Power spectrum analysis of heart rate variability in children with epilepsy.

OBJECT: Children with epilepsy have been found to be at increased risk of death during childhood. Sudden unexpected death (SUDEP) has accounted for at least 12% of deaths of children with epilepsy. The exact mechanisms of SUDEP are unknown; however, theories suggested have, to date, focused on autonomic instability. The purpose of this study was to investigate autonomic function in children with chronic epilepsy by means of power spectrum analysis of heart rate variability. METHODS: Thirty patients with epilepsy and 30 control subjects, all between the ages of 4 and 10 years, were enrolled in this study. Power spectrum analysis of heart rate variability (HRV) was performed under standardized conditions after the patients had rested for 15 min. Each patient was tested in a supine position first and then again in a head-up tilted position, with 15 min between the two tests. RESULTS: There was no significant difference between the low-frequency component (LF) and the high-frequency component (HF) of heart rate variability, or the LF/HF ratio, between the study and control groups, whether the test subjects were in the supine or the head-up tilt position. In the control group, however, the subjects showed a significantly greater LF component and a smaller HF component of heart rate variability, and a greater LF/HF ratio in the head-up position than in the supine position. This implies a normal sympathovagal balance. This phenomenon was not observed in the study group. This implies that the modulating effects on autonomic function deriving from the hemisphere were probably disturbed, owing to the brain lesions that each of the study group patients had already sustained. CONCLUSIONS: A disturbed balance of activity between the sympathetic and parasympathetic nervous system might result from the loss of hemispheric influence in patients with epilepsy. Nevertheless, further investigation is clearly necessary to ascertain the possible association of this disturbed balance with SUDEP. Further investigation is also needed to establish the exact location of the region in the brain that gives rise to this modulating influence.

Autonomic Nervous System Diseases↗

PubMed2001

Cone biopsy and pathologic findings at radical hysterectomy in stage I cervical carcinoma.

OBJECTIVE: To examine the association between cone biopsy and pathologic findings at radical hysterectomy in stage I cervical carcinoma. METHODS: Fifty-four patients diagnosed by cone biopsy with stage I cervical carcinoma and treated with radical hysterectomy comprised the study group. The association between the depth of invasion on conization, lymph-vascular invasion, positive cone margins, positive endocervical curettage (ECC), and the depth of residual invasion in the radical hysterectomy specimen was examined using Pearson r and point biserial correlation. Independent predictors of the depth of residual invasion were determined by multiple regression. RESULTS: The depth of residual invasion correlated significantly with the depth of invasion (r =.374) and presence of lymph-vascular invasion (r(pb)=.372) in the conization specimen, post-cone ECC status (r(pb) =.669), and age at diagnosis (r =.347). The same factors were jointly assessed using multiple regression (R(2) =.636, P<.001). Depth of invasion on conization, lymph-vascular invasion, and ECC status were identified as independent predictors of the depth of residual invasion. Patients with deep (5 mm or greater) stromal invasion and lymph-vascular invasion on conization had significantly higher rates of positive parametrial margins (22% compared with zero, P =.001) and adjuvant radiation (66.7% compared with 20%, P =.004) compared with all other patients. CONCLUSION: Depth of invasion, presence of lymph-vascular invasion, and age at diagnosis were independent predictors of the depth of residual invasion in the subsequent hysterectomy specimen. These factors should be considered in treatment planning. Patients with a combination of these factors may have increased risk for deep residual invasion, positive hysterectomy margins, and adjuvant radiation.

Carcinoma, Squamous Cell↗

PubMed2001

Measurements of dispersion curves of leaky Lamb waves using a lensless line-focus transducer.

This paper presents a new method of measuring dispersion curves of leaky Lamb waves propagating in a thin plate. The measurement system is based on a lens-less line-focus transducer and its defocusing measurement technique. A new waveform processing method known as V(f, z) method is introduced for analyzing the measured waveforms and for extracting the dispersion relation. For two thin-plate samples, namely a 150 microm thick alumina plate and a 320 microm thick stainless steel plate, the dispersion curves of several lower order modes of leaky Lamb waves have been experimentally determined in the frequency range of few to 25 MHz. The experimental dispersion curves have then been compared with the theoretical ones. Excellent agreement is observed. It is then verify that this method indeed provides a convenient and accurate way for experimentally measuring dispersion curves of leaky Lamb waves of thin-plate samples.

Aluminum Oxide↗

PubMed2001

Pulmonary pleomorphic (spindle) cell carcinoma: peculiar clinicopathologic manifestations different from ordinary non-small cell carcinoma.

Pleomorphic (spindle) cell carcinoma, also known as monophasic sarcomatoid carcinoma, is a rare primary pulmonary malignancy. This type of tumor shows concurrent presence of malignant epithelial and homologous sarcomatoid spindle cell components by co-expressing cytokeratin and vimentin in various degrees. Sixteen cases (four central endobronchial lesions and 12 peripheral parenchymal masses) were studied clinicopathologically. Men were affected far more frequently than women (13:3). The patients were between 56 and 80 years of age. The disease is strongly associated with smoking. Among seven of the patients who underwent surgical resection, four of them had mediastinum, pleura and chest wall invasions, and three of them had regional lymph node metastases. All of the patients succumbed to early distant metastases (range 2 weeks-5 months) in organs including brain, bone, adrenal gland, and unusual sites such as esophagus, jejunum, rectum and kidney. The remaining nine inoperable cases were late stage disease and treated with chemoradiotherapy with little effect. The median duration of survival was 3 months. All parenchymal masses appeared as cavities with marked central necrosis, and only peripheral rim of tumor cells was left. More definite diagnostic results will depend on further tissue sections and can be confirmed by immunohistochemical studies. Significantly fewer Ki-67, p53 and c-erb B-2 oncoprotein expressions were also noted.

Aged↗

PubMed2001

Chemical synthesis of a P(k)-antigenic globotriose analogue with a functionalized aglycon.

6-Aminohexyl alpha-D-galactopyranosyl-(1-->4)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranoside (2), a globotriose analogue with a functionalized aglycon, was synthesized, using alpha-D-galactopyranosyluronic acid-(1-->4)-D-galactopyranosyluronic acid [di-GalA (3)] as the starting material, which is commercially available or can be readily prepared from pectin.

Carbohydrate Sequence↗