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Biomedical subjects

B C Lee

Publications and source records attributed to B C Lee.

At least 55 records · Page 3Linked to original sources
PubMed2001

Cloning and characterization of a hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase induced in response to UV-C and wounding from Capsicum annuum.

Hydroxycinnamoyl-CoA : tyramine N-(hydroxycinnamoyl) transferase (THT) is a pivotal enzyme in the synthesis of N-(hydroxycinnamoyl)-amines, which are associated with cell wall fortification in plants. The cDNA encoding THT was cloned from the leaves of UV-C treated Capsicum annuum (hot pepper) using a differential screening strategy. The predicted protein encoded by the THT cDNA is 250 amino acids in length and has a relative molecular mass of 28,221. The protein sequence derived from the cDNA shares 76% and 67% identity with the potato and tobacco THT protein sequences, respectively. The recombinant pepper THT enzyme was purified using a bacterial overexpression system. The purified enzyme has a broad substrate specificity including acyl donors such as cinnamoyl-, sinapoyl-, feruloyl-, caffeoyl-, and 4-coumaroyl-CoA and acceptors such as tyramine and octopamine. In UV-C treated plants, the THT mRNA was strongly induced in leaves, and the elevated level of expression was stable for up to 36 h. THT mRNA also increased in leaves that were detached from the plant but not treated with UV-C. THT expression was measured in different plant tissues, and was constitutive at a similar level in leaf, root, stem, flower and fruit. Induction of THT mRNA was correlated with an increase in THT protein.

Acyltransferases↗
PubMed2001

Normal brain maturation during childhood: developmental trends characterized with diffusion-tensor MR imaging.

PURPOSE: To characterize the maturational changes in water diffusion within central gray matter nuclei and central white matter pathways of the human brain by using diffusion-tensor magnetic resonance (MR) imaging. MATERIALS AND METHODS: Retrospective analysis of normal MR examination findings in 153 subjects (age range, 1 day to 11 years) referred for clinical neuroimaging was performed. All studies included diffusion tensor-encoded echo-planar MR imaging. Isotropic diffusion coefficient (D) and diffusion anisotropy (A(sigma)) were measured in the corpus callosum, internal capsule, caudate nucleus, lentiform nucleus, and thalamus. RESULTS: exhibited biexponential decay with age in gray and white matter regions, except for monoexponential decay in the genu of the corpus callosum. There was a steep nonlinear increase of A(sigma) in white matter tracts that paralleled the time course of the decline in D. In basal ganglia, only a small linear increase in A(sigma) was observed in patients. A(sigma) changes in the thalamus were intermediate between basal ganglia and white matter structures. CONCLUSION: Changes in magnitude and anisotropy of water diffusion follow stereotypical time courses during brain development that can be empirically described with multiexponential regression models, which suggests that quantitative scalar parameters derived from diffusion-tensor MR imaging may provide clinically useful developmental milestones for brain maturity.

Brain↗
PubMed2001

Evaluation of a reduced MR imaging sequencing protocol in adult patients with stroke.

PURPOSE: To compare a reduced (three-sequence) magnetic resonance (MR) imaging protocol with a full (eight- to 10-sequence) MR imaging protocol in adults suspected of having stroke. MATERIALS AND METHODS: Six neuroradiologists interpreted a consecutive sample of 265 MR images in patients suspected of having stroke. Each read reduced-protocol images in a discrete series of 40 patients (one read images in only 15) and corresponding full-protocol images 1 month later (reduced/full protocol). Five of the readers each read images in 10 additional cases, five each as full/full and reduced/reduced protocol controls. kappa values between full and reduced protocols, reader assessment of protocol adequacy, confidence level, and need for additional sequences or examinations were evaluated. RESULTS: In the reduced/full protocol, the kappa value for detecting ischemia was 0.797; and that for detecting any clinically important abnormality, 0.635. Statistically similar kappa values were found with the full/full control design (kappa = 0.802 and 0.715, respectively). The full protocol was judged more adequate than the reduced protocol (2.0 of 5.0 points vs 1.6, P <.001) and generated greater diagnostic confidence (8.6 of 10.0 points vs 8.9, P =.01), less need for additional sequences (2.7 of 6.0 points vs 1.5, P <.001), and more requests for additional examinations (28.4% vs 36.3%). CONCLUSION: Disagreement between interpretations of reduced- and full-protocol images might be attributable to baseline-level intraobserver inconsistency, as demonstrated in control designs. A greater number of sequences did not lead to greater consistency.

Female↗
PubMed2001

Effects of sex hormones on Na+/glucose cotransporter of renal proximal tubular cells following oxidant injury.

It was reported that reactive oxygen metabolites play an important role in the pathogenesis of several renal diseases including glomerulonephritis, ischemia and acute tubular necrosis. However, the effect of oxidants and protective effect of sex steroid hormones on Na+/glucose cotransporter of renal proximal tubular cells is not yet elucidated. In the present study, we examined the effect of sex steroid hormones against tert-butyl hydroperoxide (t-BHP)-induced alteration of Na+/glucose cotransporter activity in primary cultured rabbit renal proximal tubule cells (PTCs). t-BHP inhibited alpha-methyl-D-glucopyranoside (alpha-MG) uptake in a dose-dependent manner. t-BHP-induced inhibition of alpha-MG uptake was due not to Km but to the decrease of Vmax. 0.5 mM t-BHP-induced inhibition of alpha-MG uptake was significantly blocked by estradiol-17beta, but not by progesterone and testosterone. This protective effect was not blocked by estrogen receptor antagonist or transcription and translation inhibitor. In addition, 0.5 mM t-BHP increased [3H]-arachidonic acid (AA) release and Ca2+ uptake. These effects of t-BHP were also significantly blocked by estradiol-17beta, but not by progesterone and testosterone. Protective efficacy of estradiol-17beta on t-BHP-induced inhibition of alpha-MG uptake is exhibited between antioxidants and iron chelators. In conclusion, estradiol-17beta, but not progesterone and testosterone, partially prevented t-BHP-induced inhibition of alpha-MG uptake through its antioxidant activity dependent upon phenol structures and inhibition of AA release and Ca2+ influx.

Animals↗
PubMed2001

Births of freemartins derived from embryos reconstructed with ear fibroblasts.

Although the combination of artificial insemination (AI) and embryo transfer (ET) is effective for preventing large offspring syndrome in clone cattle production, it may cause freemartinism. In this study, 51 reconstructed embryos were transferred to artificially inseminated recipients. Of those 9 twin pregnancies, three delivered male and female offsprings. The females had tufts of long coarse hair and short blind pouch at the vaginal end. At necropsy, hypoplastic testicles and epididymis, which connected to the uterus through the spermatic cord, were found and seminal vesicles were also noted. All females had mixed sex chromosome configuration (60, XX and 60, XY). These results suggest that the combined ET program can cause freemartinism, which reduces the efficiency of clone cattle production.

Animals↗
PubMed2001

A qualitative assessment of children's farm safety day camp programs.

In order to increase farm safety awareness and teach children good safety habits, farm safety day camp programs have been initiated in many communities. For the most part, the effectiveness of the programs is unknown because few evaluations have been performed. The purpose of this project was to qualitatively assess the overall strengths and weaknesses of farm safety day camp programs and to generate recommendations for future programs. Interviews, a literature search, and observations were used to identify strengths and weaknesses of the farm safety day camp programs. Major strengths of the programs are that: 1) positive attention is given to agriculture and agricultural safety; 2) programs are hands-on, interactive, and fun; 3) children gain knowledge about farm safety; 4) programs bring a community together to work toward a common goal; and 5) children talk to parents about safety. Key weaknesses of farm safety day camp programs are that: 1) there is a lack of parental involvement in many of the programs; 2) it is hard to change patterns of behavior in one day; 3) programs are expensive and time consuming; 4) curricula may include content that is inaccurate or inappropriate for the age of participants; and 5) evaluation is difficult. When done well, farm safety day camp programs can teach children about safety and influence safety practices affecting children on the farm. Recommendations for future farm safety day camp programs are: 1) ensure that child-development principles are applied to all aspects of program activities and curricula; 2) provide session leaders with accurate and relevant content; 3) increase parental involvement; and 4) address safety issues throughout the year.

Accident Prevention↗
PubMed2001

Effect of IP3 and ryanodine treatments on the development of bovine parthenogenetic and reconstructed embryos.

For parthenogenetic activation as a model system of nuclear transfer, microinjection and electroporation as activation treatments in bovine metaphase II oocytes were administered to each of three groups as follows: control group (treatments with Ca2+, Mg2+ -free PBS+100 micro M EGTA), IP3 group (control+25 micro M IP3) and IP3+ ryanodine group (control+25 micro M IP3+10 mM ryanodine). In experiments using microinjection, no significant differences were observed between any of the developmental stages of the electroporation experiment. For electroporation, cleavage rates were significantly higher in the IP3+ryanodine group than in the IP3 or control group (85.6% vs 73.7% or 67.6%, respectively). In the subsequent stages of embryonic development, such as morula and blastocyst formation, the IP3 and ryanodine group exhibited significantly higher rates of morula fomation than the IP3 or control groups (40.6% vs 24.2% or 16.7%, respectively). Similarly, the rate of blastocyst formation in the IP3+ryanodine group was significantly higher than the control group (16.3% vs 6.9%) but did not differ significantly from the IP3 group (16.3% vs 9.5%). In nuclear transfer, activation was performed at 30 hpm by microinjection and elecroporation with 25 micro M IP3+ 10 mM ryanodine followed by 6-DMAP treatment. No significant differences were observed at any stage of embryonic development and none of the embryos activated by electroporation reached either the morula or blastocyst stage. However, 3.8% and 1.9% of embryos activated by microinjection sucessfully developed to the morula and blastocyst stages, respectively. In conclusion, activation treatments using IP3 and ryanodine are able to support the development of bovine parthenogenetic and reconstructed embryos.

Adenine↗
PubMed2001

Immunohistochemical detection of Prion protein (PrP-Sc) and epidemiological study of BSE in Korea.

Though the aetiology of transmissible spongiform encephalopathies (TSEs) remains uncertain, proteinase resistant prion protein (PrP-Sc), a converted form of the normal cellular prion protein (PrP-C), accumulates in the lysosome of cells of the nervous systems of animals with TSEs. In this study, clinical and epidemiological examinations of bovine spongiform encephalopathy (BSE) were conducted in Korea. During the investigated period, none of the cattle exhibited typical clinical signs of BSE, such as behavioral disturbances, high sensitivity, and abnormal locomotion. Immunohistochemical analysis and western immunoblotting were established to detect PrP-Sc in the brain tissue using monoclonal antibody (MAb) F89/160.1.5, produced by immunizing mice with a synthetic peptide which corresponds to bovine PrP residues 146-159, NH2-SRPLIHFGSDYEDRC-COOH. Although some BSE-like spongiform changes were observed in bovine brains randomly collected from Korean slaughterhouses from 1996 to 1999, no PrP-Sc was detected in those brains with the established immunohistochemistry and western immunoblotting assay. Also, no positive reaction was observed in bovine brains infected with rabies. These immunohistochemical and western immunoblotting methods using MAbs, specifically reactive with conserved epitopes on ruminant PrP, can be used for postmortem diagnosis of BSE. Further, the method can be applied to antemortem and the preclinical diagnosis of ovine scrapie by detecting PrP-Sc in lymphoid tissues, such as the tonsils, third eyelid or peripheral lymph nodes.

Abattoirs↗
PubMed2000

Effects of pravastatin on left ventricular mass in patients with hyperlipidemia and essential hypertension.

Left ventricular (LV) mass is a powerful predictor for future cardiovascular events. Epidemiologic studies have shown that hyperlipidemia is associated with higher LV mass. The effects of statin therapy for hyperlipidemia on LV mass have not been studied. To determine the effects of statin therapy on LV mass, we prospectively studied 3 groups of age and body surface area-matched patients: group 1 (n = 20), patients with systemic hypertension and hyperlipidemia treated with pravastatin plus anti-hypertensive drugs; group 2 (n = 20), patients with hypertension and hyperlipidemia treated with hypertensive agents and diet control alone; and group 3 (n = 20), hypertensive patients with normolipidemia treated with antihypertensive agents. A group of controls without hypertension or hyperlipidemia was used for comparison. Echocardiograms were recorded at baseline and after 6-month therapy. All hypertensive groups showed significant decreases in LV mass index after treatment. Group 1 had the greatest decrease in LV mass and it was significantly higher than in groups 2 and 3. Multivariate analysis revealed that regression of LV mass was significantly correlated only with the use of statins and sex (p = 0.005 and 0.01, respectively, R(2) = 0.47). Linear regression analysis in group 1 showed a significant correlation between changes in arterial compliance and LV mass regression (r = 0.57, p = 0.01). Thus, the addition of a statin may have an additional effect on reducing LV mass, independent of lipid-lowering effects.

Echocardiography↗
PubMed2000

Importance of phosphatidylethanolamine for the interaction of apocytochrome c with model membranes containing phosphatidylserine.

The effect of phosphatidylethanolamine (PE) on the binding of apocytochrome c to model membranes was examined. When 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) of the standard vesicles composed of 80% of this lipid and 20% of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS) was gradually replaced with upward of 50% of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), the binding increased appreciably. Ca(2+), causing the phase separation of PS, also brought about increased binding of apocytochrome c in the PC/PS system, underlining the importance of PS properties in membranes for the protein binding. The resonance energy transfer between Trp-59 in apocytochrome c and pyrene-PS incorporated into bilayers showed that the replacement of PC with PE increased the extent of apocytochrome c penetration into membranes by a PE concentration-dependent manner. However, in the absence of PS, PE had no apparent effect on these functions of apocytochrome c, suggesting that PE-induced change(s) of acidic membrane properties is important to the association of apocytochrome c with vesicles. From the observations that the excimer to monomer fluorescence ratio of pyrene-PS increased and the fluorescence of NBD-PS was quenched with increasing concentration of PE, it was deduced that PE caused PS-enriched domains in PC/PE/PS membranes. The colocalization of pyrene-PS with BODIPY-PS by PE further supported the possibility. We suggest that PE-induced formation of PS-enriched domains acts as binding sites for apocytochrome c in membranes.

Apoproteins↗
PubMed2000

Palliative treatments of last resort: choosing the least harmful alternative. University of Pennsylvania Center for Bioethics Assisted Suicide Consensus Panel.

Comprehensive palliative care, as exemplified by many state-of-the-art hospice programs, is the standard of care for the dying. Although palliative care is very effective, physicians, nurses, patients, families, and loved ones regularly face clinically, ethically, legally, and morally challenging decisions throughout the dying process. This is especially true when terminally ill patients are ready to die in the face of complex, difficult-to-treat suffering and request assistance from their health care providers. Although physician-assisted suicide has received the most attention as a potential last-resort response, this practice remains illegal in the United States except in Oregon, and even there it is relatively infrequent. More commonly, decisions are made about accelerating opioid therapy for pain, foregoing life-sustaining therapy, voluntarily stopping eating and drinking, and administering terminal sedation in response to unacceptable suffering. The moral distinctions between these practices are critical to some but relatively inconsequential to others. This paper illustrates, through summaries of real clinical cases, how each of these practices might be used in response to patients in particular clinical circumstances, keeping in focus the patient's values as well as those of families, other loved ones, and health care providers. The challenge is to find the least harmful solution to the patient's problem without abandoning patients and their loved ones to unacceptable suffering or to acting in a more deleterious way on their own.

Adult↗
PubMed2000

Enantiomeric purity test of bevantolol by reversed-phase high performance liquid chromatography after derivatization with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate.

A reversed-phase high-performance liquid chromatographic method was developed to determine the optical purity of bevantolol enantiomers. (S)-(-)-Menthyl chloroformate((-)-MCF), (S)-(-)-alpha-methylbenzyl isocyanate((-)-MBIC) and 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate(GITC), which can react with the secondary amine group of bevantolol were investigated as chiral derivatization reagents. Among them indirect chiral HPLC method using GITC gave the best result. The derivatization proceeded quantitatively within 20 min at room temperature. Separation of the enantiomers as diastereomers was achieved by reversed-phase HPLC within 20min using ODS column. Different ratios of (S)-(-)-bevantolol and (R)-(+)-bevantolol were prepared. Enantiomeric separation of these mixtures took place on a chiralcel OD column or, after derivatization with GITC, on a ODS column. No racemization was found during the experiment. This method allowed determination of 0.05% of either enantiomer in the presence of its stereoisomer and method validation showed adequete linearity over the required range.

Adrenergic beta-Antagonists↗
PubMed2000

Embryotropic role of hemoglobin and ethylenediaminetetraacetic acid in preimplantation development of ICR mouse 1-cell embryos.

OBJECTIVE: To evaluate embryotropic action of hemoglobin (Hb) and ethylenediaminetetraacetic acid (EDTA) on preimplantation embryo development. DESIGN: In vitro model study using mouse embryos. SETTING: University affiliated hospital, Pochon CHA University. ANIMALS: Four-week-old block strain ICR mice naturally mated after superovulation. INTERVENTION(S): One-cell embryos were cultured in serum-free, modified preimplantation-1 medium, to which 1 microg/ml Hb and/or 0.1 mM EDTA were added. MAIN OUTCOME MEASURE(S): Preimplantation development and blastomere number. RESULT(S): More (P<.05) 1-cell embryos developed to the 4-cell (52% vs. 67%-84%), 8-cell (48% vs. 65%-81%), and blastocyst (40% vs. 61%-79%) stages after the addition of hemoglobin (Hb) and/or EDTA than after no addition. Highest proportion of embryos developed to each stage after the combined addition of Hb+EDTA. EDTA specifically stimulated the development before the 8-cell stage, which was as similar as Hb+EDTA. On the contrary, higher ratio of morula to blastocyst transformation was obtained after the addition of Hb or Hb+EDTA than after no addition (0.76 vs. 0.96-0.98). Significant increases in the cell number of blastocysts (46.5-47.2 vs. 53.2 cells), inner cell mass (ICM) cells (16.7-17.5 vs. 21 cells), and the ratio of ICM cells to trophoblasts (0.3-0.37 to 0.39) were found after the combined addition of Hb+EDTA, compared with no addition or with the addition of EDTA or Hb alone. CONCLUSIONS: Hb and EDTA have stage-specific effects on supporting preimplantation embryo development; Hb promotes both the development before the 8-cell stage and the morula to blastocyst transformation, whereas EDTA mainly promotes the development to the 8-cell stage. The combined exposure of embryos to Hb and EDTA improves not only preimplantation development but also the growth and quality of blastocysts.

Animals↗
PubMed2000

The role of percutaneous biopsy in detection of pancreatic transplant rejection.

The purpose of this study was to investigate the effectiveness and safety of percutaneous pancreatic transplant biopsy guided by ultrasound alone or with a combination of computerized tomography (CT) for pancreas localization and ultrasound for needle placement. We also compare our finding on the use of 18-gauge and 20-gauge needles for percutaneous pancreatic transplant biopsy. In 42 attempted biopsies performed on 21 patients, two different imaging modalities were used. Twenty-seven attempted biopsies were performed under the guidance of ultrasound alone, and 15 used a combination of ultrasound and CT. Of the 27 ultrasound-guided biopsies. 24 produced at least one sample adequate for histopathological analysis for an 89% biopsy success rate. Of the 15 biopsies guided by combined ultrasound and CT, 11 produced adequate samples for a 73% success rate. For all biopsies, an 83% success rate was found. In assessing the use of 18-gauge versus 20-gauge needles, 86 out of 110 tissue cores were adequate for histopathological analysis for a 78% yield. In 27 biopsy attempts using the 18-gauge needle, 75 tissue cores were obtained, for an average of 2.8 cores per biopsy. Fifty-seven pancreas samples collected using the 18-gauge needle were adequate for pathological evaluation for a 76% yield. With 15 biopsy attempts using the 20-gauge needle, 35 tissue cores were collected, for an average of 2.3 cores per biopsy. Twenty-nine pancreas specimens obtained from using the 20-gauge needle were adequate for analysis for an 83% yield. No major complications occurred. Only one incidence of minor complication was reported for a 2% complication rate. The only complication was local, mild bleeding at the biopsy site in one case. Air within the transplant pancreas as revealed by post-biopsy scans and streaky density appearing adjacent to the biopsy site occurred in a total of four cases and were not included. No complications were reported that required any invasive intervention. We conclude that percutaneous biopsy guided by ultrasound is a safe, simple, and effective method to detect pancreatic transplant rejection. Our results for biopsies compare favorably with other reported techniques in terms of effectiveness, complication rates, and ease of use. With its high success rate and low complications, ultrasound-guided percutaneous biopsy is an excellent method to sample pancreatic transplant.

Adult↗
PubMed2000

Development of porcine oocytes from preovulatory follicles of different sizes after maturation in media supplemented with follicular fluids.

The development of porcine oocytes from large (3.1-8.0 mm in diameter) or small (<3.1 mm) follicles was examined after maturation culture in medium containing porcine follicular fluid (pFF). Large follicles yielded larger (256 microm v. 221 microm; P<0.05) cumulus-oocyte complexes and more (22 v. 14%) morphologically normal oocytes than small follicles (Experiment 1). In Experiments 2-4, maturation media supplemented with mixed pFF (10%) from small and large follicles was used. More oocytes from large follicles matured (58% v. 91%), formed pronuclei (81% v. 90%) and developed to the blastocyst stage (2% v. 10%) than oocytes from small follicles. In Experiments 5-7, the effects of pFF collected from either small or large follicles on oocyte development were examined. Regardless of the source of oocytes, large-follicle-derived pFF more significantly enhanced preimplantation development than did small-follicle-derived pFF. The highest rate of blastocyst formation (16%) was found when oocytes from large follicles were cultured in maturation medium containing large-follicle-derived pFF. These results suggest that oocytes from large follicles have greater developmental potential than oocytes from small follicles, and that the origin of pFF, which is added to the maturation media, might be an important factor for improving in vitro development of porcine oocytes.

Animals↗
PubMed2000

fbpABC gene cluster in Neisseria meningitidis is transcribed as an operon.

The neisserial fbpABC locus has been proposed to constitute a single transcriptional unit. To confirm this operonic arrangement, transcription assays using reverse transcriptase PCR amplification were conducted with Neisseria meningitidis. The presence of fbpAB and fbpBC transcripts obtained by priming cDNA synthesis with an fbpC-sequence-specific oligonucleotide indicates that fbpABC is organized as a single expression unit. The ratio of fbpA to fbpABC mRNA was approximately between 10- to 20-fold, as determined by real-time quantitative PCR.

Bacterial Proteins↗