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Biomedical subjects

Y C Li

Publications and source records attributed to Y C Li.

At least 37 records · Page 2Linked to original sources
PubMed2001

Protein kinase C is involved in the regulation of hairless mRNA expression during mouse keratinocyte differentiation.

The hairless (hr) gene is a putative transcriptional factor whose mutations lead to hair loss in animals and humans. As a step toward understanding the role of the hr gene, we investigated the expression of hr mRNA in mouse keratinocyte differentiation. Treatment of mouse primary keratinocyte cultures with phorbol-12-myristate-13-acetate (PMA) reduced DNA synthesis and sequentially induced an up-regulation of p21Cip1/WAF1 (p21), hr and involucrin (inv) mRNAs in a time-dependent fashion, suggesting that an increase in hr gene expression is associated with keratinocyte differentiation. This up-regulation was blocked by the RNA synthesis inhibitor actinomycin D. However, an increase in hr mRNA, but not in inv mRNA, was seen in cells treated with the protein synthesis inhibitor cycloheximide, suggesting that new protein synthesis is involved in the suppression of hr transcription or in the degradation of hr mRNA in the steady state. The up-regulation of hr mRNA expression by PMA was blocked by the protein kinase C (PKC) inhibitor, GF109203X. These data indicate that PKC activation is involved in the up-regulation of hr mRNA expression during mouse keratinocyte differentiation.

Animals↗
PubMed2001

Shielding of protein-boronate interactions during boronate chromatography of neoglycoproteins.

A method for separating glycoproteins on a boronate column under conditions which suppress the interactions between the protein moiety and the boronic acid ligand has been developed. A model system consisting of non-glycosylated chymotrypsin and maltose-modified chymotrypsin (cht-mal) was utilised in the investigations. Chymotrypsin was chosen as the model protein because of its known interaction with boronate. By coupling maltose to chymotrypsin, a neoglycoprotein was created which has the property of binding to the affinity matrix both via the protein moiety and via the carbohydrate residues. The introduction of a so-called shielding reagent into the buffer solutions during chromatography resulted in the prevention of the protein-boronate interactions while the carbohydrate-boronate interaction was little influenced. Different types of, mainly low-molecular-mass, polyhydroxyl chemicals were screened in order to correlate the shielding efficiency to the chemical structure of the investigated compounds. Polyhydroxyl chemicals with a conformation that allows the formation of tridentate complexes with the boronate anion provided the highest shielding efficiencies.

Boronic Acids↗
PubMed2001

Establishment of transcriptional silencing in the absence of DNA replication.

Transcriptional repression of the silent mating-type loci in Saccharomyces cerevisiae requires a cell cycle-dependent establishment step that is commonly assumed to involve DNA replication. Using site-specific recombination, we created a nonreplicating DNA ring in vivo to test directly the role of replication in establishment of silencing. Sir1 was tethered to the ring following excision from the chromosome to activate a dormant silencer. We show here that silencing can be established in DNA that does not replicate. The silenced ring adopted structural features characteristic of bona fide silent chromatin, including an altered level of DNA supercoiling and reduced histone acetylation. In addition, the process required silencing factors Sir2, Sir3, and Sir4 and progression between early S and M phases of the cell cycle. The results indicate that passage of a replication fork is not the cell-cycle event required for establishment of silencing in yeast.

Acetylation↗
PubMed2001

Luteolin-inhibited arylamine N-acetyltransferase activity and DNA-2-aminofluorene adduct in human and mouse leukemia cells.

N-Acetyltransferase enzyme is an important enzyme in the first step of arylamine compounds metabolism. Luteolin has been shown to exit antibacterial and antineoplastic activity. The purpose of this present study is to evaluate the question of whether luteolin could affect arylamine N-acetyltransferase (NAT) activity and DNA-2-aminofluorene adduct formation in human (HL-60) and mouse (L1210) leukemia cells. By using HPLC, N-acetylation of 2-aminofluorene was determined. Luteolin displayed a dose-dependent inhibition to cytosolic NAT activity and intact human and mice leukemia cells. Time-course experiments showed that N-acetylation of 2-aminofluorene measured from intact human and mice leukemia cells were inhibited by luteolin for up to 24 hours. Using standard steady-state kinetic analysis, it was demonstrated that luteolin was a possible uncompetitive inhibitor to NAT activity in cytosols. The DNA-2-aminofluorene adduct formation in human and mouse leukemia cells were inhibited by luteolin. This report is the first demonstration to show that luteolin affects human and mice leukemia cells NAT activity and DNA-2-aminofluorene on adduct formation.

2-Acetylaminofluorene↗
PubMed2001

Inhibitory actions of luteolin on the growth and arylamine N-acetyltransferase activity in strains of Helicobacter pylori from ulcer patients.

Helicobacter pylori is now recognized as an important cause of type B gastritis, which is strongly associated with gastric and duodenal ulcer disease. H. pylori may be a causative factor in patients with gastric cancer. The growth inhibition and N-acetylation of 2-Aminofluorene (AF) or P-aminobenzoic acid (PABA) by arylamine N-acetyltransferase (NAT) in H. pylori were inhibited by luteolin, a component in herbal medicine. The growth inhibition was based on the changes of optical density (OD) by using a spectrophotometer. The N-acetylation of AF or PABA by NAT from H. pylori were assayed by the amounts of acetylated and non-acetylated AF or PABA in cytosols and intact bacteria of H. pylori by using HPLC. An inhibition of growth on H. pylori demonstrated that luteolin elicited a dose-dependent growth inhibition in the H. pylori cultures. Cytosols and suspensions of H. pylori with or without specific concentrations of luteolin co-treatment showed different percentages of AF or PABA acetylation. The data indicated that there was decreased NAT activity associated with increased levels of luteolin in H. pylori cytosols and suspensions. Using standard steady-state kinetic analysis, it was demonstrated that luteolin was a possible uncompetitive inhibitor to NAT enzyme in H. pylori. This report is the first demonstration to show that luteolin can inhibit H. pylori growth and NAT activity.

4-Aminobenzoic Acid↗
PubMed2001

Sharing patient care records over the World Wide Web.

In order to obtain appropriate medical care, patients can be referred or transported from one hospital to another based on the capacity, capability and quality of medical care provided by hospitals. Therefore, enabling patient care records to be shared among hospitals is essential not only in delivering the quality of medical care services but also in saving medical expenses. Currently, most patient care records are paper-based and not well organized. Hence, they are usually incomplete and can hardly be accessed in time. The authors in this paper present methods to structure and represent patient care records, design mechanisms for interpreting and integrating the XML-based patient care records into the existing hospital information systems. More importantly, in our approach, each significant piece of medical record is associated with a tag based on the syntax and semantics of the XML. The XML-based medical records enable a computer to capture the meaning and structure of the document on the web. The authors have developed a unified referral information system in which patient care records can be shared among hospitals over the Internet. It can not only facilitate the referral process but also maintain the integrity of a patient's medical record from distributed hospitals. The workflow of the system basically follows the existing manual system and can easily be adapted. The working group on integration of municipal hospital information systems, Department of Health, Taipei City Government, has decided to adapt this system for referral practice among the municipal hospitals.

Hospital Information Systems↗
PubMed2001

Building a generic architecture for medical information exchange among healthcare providers.

Due to the inability to exchange clinical information among hospitals, continuity of care cannot be maintained and a tremendous amount of medical resource has been wasted. This paper describes an architecture that would facilitate exchange of clinical information among heterogeneous hospital information systems. It is dubbed 'Medical Information Exchange Center' or MIEC as part of a six-year Health Information Network Project hosted by the Department of Health. MIEC was designed so that it is innovative yet technically feasible today. It is convenient for authorized users yet secure enough so people can trust and has minimal impact to participated hospitals. Authorized users will be able to access information through two web-based interfaces directed to physician and non-physician users respectively. Hospitals are connected through a virtual private network to exchange patient information and users need to obtain a private key from the certificate authority in order to securely connect to MIEC. A pilot project was conducted to demonstrate the feasibility of this architecture and the problems encountered were discussed.

Computer Communication Networks↗
PubMed2001

Development and deployment of a web-based physician order entry system.

The computer-based Physician Order Entry System (POES) has been employed in many clinical institutes in Taiwan. Most of the POES systems are developed in the two-tier client-server architecture, and a large portion of the systems are constructed on a mainframe or even a single PC. The exponential growth of the Internet has had a tremendous impact on our society in recent years. In consideration of the future user interface and system architecture, we have developed a three-tier web-based Physician Order Entry System and successfully deployed it in the Wang-Fang Hospital in Taipei. The system is the first POES based on three-tier and World Wide Web (WWW) in Taiwan. The system provides the Subjective, Objective, Assessment, and Plan (SOAP) structure for the physician to enter subject, object, diagnoses, medicine dosage, treatment and laboratory test request, and prints out the prescription and necessary document. The doctor can also retrieve the patient's medical record on the system. One of the special characteristics of the system is its personalized design. The doctor can define their own diagnosis, medicine and treatment database and any combination of these to facilitate their clinical work. The system has been reviewed since February 1999. The result shows that the clinical procedure has become more efficient, and the chances of omission have been reduced. The system is very stable and the Open Database Connectivity (ODBC) database access did not show any delay in the network. Since we have incorporated many new web-programming techniques, the progress of the techniques will improve the system performance in the future.

Computer Systems↗
PubMed2001

Geometric analysis of potential error in using femoral intramedullary guides in total knee arthroplasty.

Proper component orientation is necessary for the long-term success of a total knee arthroplasty. Femoral component placement has used jigging systems that are based on intramedullary and extramedullary guides. The intramedullary system has been shown to foster more accurate and reproducible placement of the femoral component. This study analyzed and quantified the potential error of the intramedullary guide system. Geometric data of the human femur were obtained from radiographs of 45 cadaver femora in the anteroposterior and lateral views. The correct entry point of the intramedullary rod in the distal femur is the midaxial line of the femoral canal on anteroposterior and lateral radiographs. The position of this point in relation to the mediolateral and anteroposterior dimensions of the distal femur was calculated as a ratio. The average calculated ratios were anteroposterior, 0.53 offset medially; lateral, 0.32 offset anterior. Mathematical models were constructed to quantify the potential varus valgus and flexion extension error of the guide rods. Variables investigated were entry point location, guide rod diameter, guide rod length, and rotation. The surgeon must be cognizant of these potential sources of error to maximize the accuracy of the femoral intramedullary jigging system.

Arthroplasty, Replacement, Knee↗
PubMed2001

Two novel phenolic triterpenes from Tripterygium wilfordii.

Two novel phenolic triterpenes were isolated from Tripterygium wilfordii Hook. f., their structures were identified to be 2,3-dihydroxy-1,3,5(10),8-tetra-ene-6alpha-(2'-hydroxyethyl)-24-nor-D:A-friedooleanane-29-oic acid 1, named triptotin F, and 2,3-dihydroxy-1,3,5(10),8-tetra-ene-6beta-(2'-hydroxyethyl)-24-nor-D:A-friedooleanane-29-oic acid 2, named triptotin G on the basis of spectroscopic studies.

Celastraceae↗
PubMed2001

Effects of (-)-menthol on arylamine N-acetyltransferase activity in human liver tumor cells.

To evaluate whether or not (-)-menthol affects arylamine N-acetyltransferase (NAT) activity, we selected human liver tumor cell line (J 5) for examination. By using high performance liquid chromatography, NAT activity for acetylation of 2-aminofluorene (AF) was determined. (-)-Menthol displayed a dose-dependent inhibition to cytosolic NAT activity. Time-course experiments showed that NAT activity measured from intact human liver tumor cells was inhibited by (-)-menthol for up to 24 hrs. But in human liver tumor intact cells, the low doses (0.0032 and 0.032 mM) of (-)-menthol promoted the NAT activity and the high doses (3.2 and 32 mM) of (-)-menthol inhibited NAT activity and the 0.32 mM (-)-menthol did not show any significant differences between control and (-)-menthol treated groups. Using standard steady-state kinetic analysis, it was demonstrated that (-)-menthol was a possible uncompetitive inhibitor (decrease Km and Vmax) to NAT activity in cytosols. This report is the first demonstration which showed (-)-menthol affect on human liver tumor cells NAT activity.

Antineoplastic Agents↗
PubMed2001

Effects of vitamin D receptor inactivation on the expression of calbindins and calcium metabolism.

Hypocalcemia, rickets, and osteomalacia are major phenotypic abnormalities in vitamin D receptor (VDR)-null mice. In an attempt to understand the abnormal regulation of calcium metabolism in these animals, we examined the expression of calbindins (CaBP) as well as calcium handling in the intestine and kidney of VDR null mice. In adult VDR-null mice, intestinal and renal CaBP-D9k expression was reduced by 50 and 90%, respectively, at both the mRNA and protein levels compared with wild-type littermates, whereas renal CaBP-D28k expression was not significantly changed. Intestinal calcium absorption was measured by the rate of (45)Ca disappearance from the intestine after an oral dose of the isotope. (45)Ca absorption was similar in VDR-null and wild-type mice, but the amount of (45)Ca accumulated in the serum and bone was 3-4 times higher in wild-type mice than in VDR-null mice. Despite the hypocalcemia, the urinary excretion of calcium in VDR-null mice was not different from that in wild-type mice. Moreover, 1 wk of a high-calcium diet treatment that normalized the serum ionized calcium level of VDR-null mice increased the urinary calcium level of these mutant mice to twofold higher than that of wild-type mice on the same diet, suggesting impaired renal calcium conservation in VDR-null mice. These data demonstrate that renal CaBP-D9k, but not CaBP-D28k, is highly regulated by the VDR-mediated action of 1,25-dihydroxyvitamin D(3). Furthermore, the results also suggest that impaired calcium conservation in the kidney may be the most important factor contributing to the development of hypocalcemia in VDR-null mice, and CaBP-D9k may be an important mediator of calcium reabsorption in the kidney.

Animals↗
PubMed2001

Pathogenesis of lumbosacral lipoma: a test of the "premature dysjunction" theory.

Premature separation of the neuroectoderm from the ipsilateral surface ectoderm allowing mesenchymal tissue to invade into the central canal, or "premature dysjunction" theory, was proposed for the pathogenesis of dorsal type lumbosacral lipoma. To test this theory, the unilateral neural fold was incised using Hamburger and Hamilton stage 12 or 13 chick embryos. Among 35 embryos evaluated, 15 showed abnormal findings, and of these one showed findings which suggested lumbosacral lipoma: a back lump, blending of the neuroepithelium and mesenchyme through indistinct basement membrane and vertebral body abnormalities. The other 14 embryos showed abnormalities including blunt tails, open neural tube defects, incomplete closure of the dorsal neuroepithelium with intact skin, skin dimples, disorganized gray matter, scoliosis, ectopic neuroepithelium and an accessory spinal cord. The results revealed that the incision of the unilateral neural fold in the early chick embryo may produce a lesion suggestive of lumbosacral lipoma, a finding which supports the premature dysjunction theory. This method needs further refinement to overcome technical difficulties, high mortality, and a low yield before being adopted as an experimental model for lumbosacral lipoma.

Animals↗
PubMed2001

Adult Wilms' tumor associated with polycythemia--a case report.

Both Wilms' tumor (nephroblastoma) in adults and polycythemia in Wilms' tumor are rare. Herein we report an extremely rare case of adult Wilms' tumor associated with polycythemia. A 41-year-old female was incidentally found to have right renal mass by abdominal sonography in a routine health examination. Laboratory examination revealed polycythemia (hemoglobin 20.2 g/dL). Although physical examination was unremarkable, CT scan revealed an homogeneous mass at the middle pole of right kidney, and chest x-ray revealed no metastatic lesions. Right radical nephrectomy was performed smoothly. Grossly, the tumor of 5 x 4.5 x 4.5 cm in size was well circumscribed, and had no vascular structure or collecting system involvement. Microscopic features were consistent with adult nephroblastoma. The post-operative course was uneventful. At follow-up, the patient was well, showed no evidence of recurrence and her hemoglobin level had returned to normal (hemoglobin 14.5 g/dl). We suggest that the relationship between polycythemia and Wilms' tumor should be carefully evaluated before surgical treatment.

Adult↗
PubMed2001

Pharmacokinetics of lactosaminated recombinant human growth hormone in mice.

AIM: To study the pharmacokinetic characteristics of lactosaminated recombinant human growth hormone (hGH-L) in mice. METHODS: The biodistribution was studied with in vivo radioactive tracer technique. The pharmacokinetics was investigated by radioimmunoassay (RIA) method of hGH-L. The results were compared with that of recombinant human growth hormone (hGH). RESULTS: 125I-hGH-L has remarkable livertaxis. The area under drug concentration-time curve (32686.9 microg . min . L-1) in blood and serum mean residence time (21.4 min) of hGH-L are less than that of hGH (36913.1 microg . min . L-1 and 24.9 min) (P < 0.05). In target organ liver, hGH-L distribution half life (1.8 min) and elimination half life (11.1 min) are shorter than that of hGH (2.1 min and 27.7 min) (P < 0.05). The area under drug concentration-time curve (17621.9 microg . min . L-1) of hGH-L is bigger than that of hGH(12148.2 microg . min . L-1) (P < 0.05) in liver. CONCLUSION: The pharmacokinetic parameters of hGH-L has obvious advantage over that of hGH.

Amino Sugars↗
PubMed2001

[Study of sesquiterpene alkaloids from Tripterygium wilfordii Hook.f].

AIM: To study the chemical composition of Tripterygium wilfordii Hook.f. METHODS: Column chromatography was used to separate the chemical constituents. UV, IR, MS, HRMS, 1HNMR, 13CNMR (COM and OFR), 1H-1H COSY, 1H-13C COSY, 2D-NOESY and 1H-13C COLOC were used to determine the structures of the isolated constituents. RESULTS: Two sesquiterpene alkaloids were isolated and their structures were elucidated as euonine and wilfordconine on the basis of spectral evidence. CONCLUSION: Wilfordconine, a new sesquiterpene alkaloid, was shown to be immunosuppressive.

Alkaloids↗
PubMed2000

A combined system for measuring animal motion activities.

In this study, we have developed a combined animal motion activity measurement system that combines an infrared light matrix subsystem with an ultrasonic phase shift subsystem for animal activity measurement. Accordingly, in conjunction with an IBM PC/AT compatible personal computer, the combined system has the advantages of both infrared and ultrasonic subsystems. That is, it can at once measure and directly analyze detailed changes in animal activity ranging from locomotion to tremor. The main advantages of this combined system are that it features real time data acquisition with the option of animated real time or recorded display/playback of the animal's motion. Additionally, under the multi-task operating condition of IBM PC, it can acquire and process behavior using both IR and ultrasound systems simultaneously. Traditional systems have had to make separate runs for gross and fine movement recording. This combined system can be profitably employed for normative behavioral activity studies and for neurological and pharmacological research.

Amphetamine↗