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Biomedical subjects

Y T Wu

Publications and source records attributed to Y T Wu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Recovery of endo-polygalacturonase using polyethylene glycol-salt aqueous two-phase extraction with polymer recycling.

The partitioning behaviour of endo-polygalacturonase (endo-PG) and total protein from a clarified Kluyveromyces marxianus fermentation broth in polyethylene glycol (PEG)-ammonium sulfate and PEG-potassium phosphate (pH=7) aqueous two-phase systems was experimentally investigated. Both the enzyme and total protein partitioned in the bottom phase for these two kinds of systems. The enzyme partitioning coefficient can be lower than 0.01 in PEG8000-(NH4)2SO4 ATPS with a large phase volume ratio and a moderate tie-line length, which implies the possibility of concentration operation using aqueous two phase partitioning. An ion-exchange separation of high purification efficiency was applied to analyze the clarified and dialyzed fermentation broth. A total purification factor of only 2.3 was obtained, which indicated the high enzyme protein content in the total protein of the fermentation broth. Consequently, the main purpose for separating endo-PG is concentration rather than purification. A separation scheme using an aqueous two-phase extraction process with polymer recycling and a dialysis was proposed to recover endo-PG from the fermentation supernatant of K. marxianus for commercial purpose. A high enzyme recovery up to 95% and a concentration factor of 5 to 8 with a purification factor of about 1.25 were obtained using the single aqueous two-phase extraction process. More than 95% polymer recycled will not affect the enzyme recovery and purification factor. Dialysis was used mainly to remove salts in the bottom phase. The dialysis step has no enzyme loss and can further remove small bulk proteins. The total purification factor for the scheme is about 1.7.

Ammonium Sulfate↗
PubMed2000

Unicystic ameloblastoma: a clinicopathologic study of 33 Chinese patients.

The term unicystic ameloblastoma refers to those cystic lesions that show clinical, radiographic, or gross features of a jaw cyst, but on histologic examination show a typical ameloblastomatous epithelium lining part of the cyst cavity, with or without luminal and/or mural tumor growth. To ascertain the clinicomorphologic spectrum and biologic behavior of this tumor group, the clinicopathologic features of 33 unicystic ameloblastomas from Chinese patients were studied. This series represents approximately 19% of all cases of ameloblastoma accessioned in the authors' hospital during a 15-year period. Twenty-one patients were male and 12 were female, for a total of 33 patients. The age at diagnosis ranged from 8 to 60 years (mean, 25.3 yrs) and peaked at the second and third decades (70%), Thirty tumors (91%) occurred in the mandible and three in the maxilla. Of the 29 patients with a radiographic record, an expansive unilocular radiolucency was seen in 22 cases, and was multilocular in seven cases. Microscopically, all tumors demonstrated a generally monocystic growth pattern. Eight tumors were simple cystic, 10 comprised intraluminal tumor nodules, and the remaining 15 had a conspicuous component of infiltrative tumor islands in the cyst capsule. The cystic tumor linings invariably showed, at least in part, a typical ameloblastomatous pattern that was often accompanied by epithelial areas of various histologic appearance. Follow up of 29 patients revealed no recurrence in less than 4 years of follow up, but did reveal a 35% recurrence rate at more than 4 years of follow up. The average interval to recurrence was approximately 7 years. Recurrence also appeared to relate to histologic subtypes of unicystic ameloblastoma, with those invading the fibrous wall having a rate of 35.7%, but other types having a rate of 6.7%. Despite the fact that unicystic ameloblastoma may, in general, compare favorably with its solid or multicystic counterpart in terms of clinical behavior and response to treatment, the subsets of the maxillary lesions or tumors containing invading islands in the fibrous wall could have a high risk of recurrence. Furthermore, recurrence of unicystic ameloblastoma may be long delayed, and a long-term postoperative follow up is essential to the proper management of these patients.

Adolescent↗
PubMed2000

Physical activity, physical fitness, and osteopenia in postmenopausal Taiwanese women.

BACKGROUND AND PURPOSE: The purpose of this cross-sectional study was to investigate whether physical activity level and physical fitness parameters differ between postmenopausal Taiwanese women with normal and subnormal bone mineral density (BMD). METHODS: Seventy-six postmenopausal women aged from 42 to 65 years participated in this study. Women taking medication that might influence BMD measurements were not included. The BMDs of the lumbar spine (L2-4) and right femoral neck were measured using dual energy x-ray absorptiometry. Thirty-one women with both BMD values within the normal ranges (1.055 +/- 0.092 g/cm2 for the spine and 0.845 +/- 0.088 g/cm2 for the right femoral neck) of premenopausal Chinese women served as the normal density group. Another 43 women with both BMD values more than one standard deviation below the normal value (0.760 +/- 0.089 g/cm2 for the spine and 0.656 +/- 0.052 g/cm2 for the femoral neck) were recruited as the osteopenic group. Physical activity level was assessed with a 7-day recall questionnaire. Physical fitness assessment included tests of flexibility, muscular strength, endurance, body composition, and cardiopulmonary fitness. A multiple linear regression model adjusted for age, body weight, height, and years since menopause was used. RESULTS: The results revealed that energy expenditure and maximal oxygen consumption were significantly lower in the osteopenic group than in the non-osteopenic group (p < 0.05), while flexibility, body composition, muscle strength and muscular endurance did not differ significantly between the two groups (p > 0.05). CONCLUSIONS: These findings indicate that physical activity may play a major role in BMD levels in postmenopausal women in Taiwan. Future studies should emphasize the effect of physical exercise training on BMD in postmenopausal women.

Adult↗
PubMed2000

[A recombinant fowlpox virus expressing the fusion protein of Newcastle disease virus strain F48E8 and its protective efficacy].

The transfer vector pFGF1175-1 was constructed by insertion the fusion protein gene of Newcastle disease virus (NDV) F48E8 strain into the insertion vector pFG1175-1, downstream of P7.5 promotor, and then transfected chicken embryo fibroblast (CEF) cell cultures which had been infected with fowlpox virus (FPV) Chinese vaccine strain 282E4 for 3-4 hours. Recombinant FPV with blue plaques were selected and purified in CEF cell culture laid agar containing X-gal. The recombinant FPV named rFPV-NDF was confirmed expressing NDV fusion protein by indirect immunofluorescence assay, and could protect chickens against virulent NDV challenge, The protective rate was 96.7%.

Animals↗
PubMed2000

[Foundational study of subcritical water chromatography].

AIM: To study the subcritical water chromatographic discipline of compounds with medium and high polarity on the capillary and packed column. METHODS: A packed and capillary subcritical water chromatography-FID detection system was built up. Six alcohols were well separated on a C18 column and the influence of temperature on chromatographic behavior of alcohols with different polarity was studied. The influence of temperature and pressure on chromatographic behavior of benzoic acid and gensenoside Rg1 on a SE-54 capillary column were also studied. RESULTS: Increasing temperature resulted in the decreasing polarity of mobile phase, shortened retention times of components separated, narrowed peak shape and improved tailing as well. CONCLUSION: Temperature programming could be used successfully to separate compounds with various polarity selectively. Thermostable capillary column could enlarge the range of temperature even more.

Chromatography, Liquid↗
PubMed2000

[Detection of impurities in DNA samples by using the convolution spectrum method].

AIM: To detect the presence of phenol, amino acids and endotoxin in DNA preparations. METHODS: By using the convolution curve transformation technology, correlation coefficient discriminant which was put forward by spectrum space theory and computer information process technology, impurities in DNA samples were detected. RESULTS: The convolution spectrum method compared with A260/A280 ratio method and second-derivative absorption spectrum method could be used for the semiquantitative determinations of impurities in DNA samples and the results were satisfactory. CONCLUSION: The method was simple, convenient, fast and valuable to the biochemical analysis.

Amino Acids↗
PubMed2000

[Distinguish of the original fungi of the Chinese traditional medicine, hongqu with gas chromatography fuzzy clustering analytical method].

OBJECTIVE: To establish a gas chromatography fuzzy clustering analytical method for classifying of origin fungi of the Chinese traditional medicine, Hongqu. METHODS: The volatile and nonvolatile components of 7 ordinary species of Monascus including M. aurantiacus Lee, etc. were analyzed by capillary gas chromatog raphy using FID: Inlet temperature 280 degrees C, detector temperature 280 degrees C, temperature program 130 degrees C, 5 min-->10 degrees C.min-1-->200 degrees C, 10 min. RESULTS: In the peak number and contents of volatile and nonvolatile components of Monascus exist obviously differences through which Monascus can be distinguished easily by the main fingerprint peaks within 20 minutes. CONCLUSION: The capillary gas chromatography fuzzy clustering analytical method is useful to the identification of Monascus fungi.

Chromatography, Gas↗
PubMed2000

[Determination of major components in liuyingwan pills by supercritical fluid extraction(SFE)].

OBJECTIVE: On the basis of SFE and CGC to establish a method for the qualitative and quantitative analysis of major components in Liuyingwan pills. METHOD: Orthogonal design and variance analysis were used to optimize the four variables (temperature, pressure, volume of modifier and static extraction time) of SFE, and the quantification was completed by CGC. RESULT: The optimized conditions are as follows: pressure 48.2 MPa, temperature 60 degrees C, 0.2 ml ethyl acetate as modifier and static extraction 10 min. The recoveries of borneol and eugenol are 101.93% (RSD 1.56%) and 98.43% (RSD 2.26%) respectively. CONCLUSION: Compared with conventional methods, SFE is rapid, convenient and accurate in determining borneol and eugenol.

Camphanes↗
PubMed2000

[Determination of major components in Psoralea corylifolia L. by using supercritical fluid extraction (SFE)].

A method based on SFE and CGC has been developed for qualitative and quantitative analysis of major components in Psoralea corylifolia L.. The orthogonal design method and the analysis of variance are used to optimize the five variables (temperature, pressure, volume of modifier, static extraction time and CO2 dynamic extracting volume) of SFE and the optimized conditions listed as follows: temperature 70 degrees C, pressure 38.5 MPa, static extraction 1 min, dynamic extraction 7 mL and 60 microL CHCl3 as modifier. The recoveries of psoralen and isopsoralen are 96.93% (RSD 1.87%) and 98.43% (RSD 2.06%) respectively. Being compared with conventional methods, the SFE as an alternative technique for sample preparation will be most useful in the quality control of Chinese traditional medicines.

Chromatography, Gas↗
PubMed2000

[Effect of sample solvents on retention in packed column supercritical fluid chromatography].

Factors affecting the retention in supercritical fluid chromatography(SFC) on C18 and NH2 packed columns have been studied. These factors include the sampling solvent, continuous injection, stationary phase type and concentration of modifier. When supercritical carbon dioxide or low concentration(less than 0.5%) of methanol is employed as the mobile phase, retention time increases with the polarity of the solvent on NH2 column, while it keeps almost constant on C18 column. Methanol will cover the active sites on the surface of the bonded phase, forming the "pseudo" stationary phase, which will lower the interaction between the analytes and the stationary phase, hence the shorter will be the retention time. The hydrogen bond between stationary phase (including the amino group and the remaining hydroxyl group) and methanol is the most obvious. So it's quite more evident on NH2 column than on C18 column that the delaying effect of the solvent, with methanol, acetone and chloroform in decreasing sequence, encourages the elution of the analytes during continuous injections. The elution will recover to the first injection after adequate interval has passed, i.e., more than 10 column volumes. When the methanol concentration is greater than 1.0% in carbon dioxide, the effect decreases and becomes negligible. The solvent effect is significant to the reasonable injection and reproducible chromatographic data in packed column SFC.

Carbon Dioxide↗
PubMed1999

Determination of ferulic acid in Angelica sinensis and Chuanxiong by capillary zone electrophoresis.

Ferulic acid in extracts of raw herbs was separated by capillary zone electrophoresis in the buffer solution of 10 mmol/L Na(2)B(4)O(7). The simple and rapid method was linear, ranging from 5 to 100 microg/mL, and had a good reproducibility with the RSD below 2%. The contents of ferulic acid in Angelica sinensis and Chuanxiong could be easily determined within 15 min with no pretreatment and no interference.

Coumaric Acids↗
PubMed1999

Determination of glycyrrhizin in radix glycyrrhizae and its preparations by capillary zone electrophoresis.

A capillary zone electrophoresis method was set up for the separation and determination of glycyrrhizin in Chinese medicinal preparations. Concentrations of Na(2)B(4)O(7) were optimized, which showed that glycyrrhizin in the sample could be separated from interference in the running buffer of 30 mmol/L Na(2)B(4)O(7). Using declofenac as internal standard, the simple method was linear in the range 25-300 microg/mL of glycyrrhizin, and good reproducibility was obtained. The extracts of Radix glycyrrhizae and its preparations could be injected directly for analysis without any pretreatment.

Animals↗
PubMed1999

Determination of berberine in Rhizoma coptidis and its preparations by non-aqueous capillary electrophoresis.

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.

Anti-Infective Agents, Local↗
PubMed1999

Direct solid-phase synthesis of octreotide conjugates: precursors for use as tumor-targeted radiopharmaceuticals.

Somatostatin analogues, such as octreotide, are useful for the visualization and treatment of tumors. Unfortunately, these compounds were produced synthetically using complex and inefficient procedures. Here, we describe a novel approach for the synthesis of octreotide and its analogues using p-carboxybenzaldehyde to anchor Fmoc-threoninol to solid phase resins. The reaction of the two hydroxyl groups of Fmoc-threoninol with p-carboxybenzaldehyde was catalyzed with p-toluenesulphonic acid in chloroform using a Dean-Stark apparatus to form Fmoc-threoninol p-carboxybenzacetal in 91% yield. The Fmoc-threoninol p-carboxybenzacetal acted as an Fmoc-amino acid derivative and the carboxyl group of Fmoc-threoninol p-carboxybenzacetal was coupled to an amine-resin via a DCC coupling reaction. The synthesis of protected octreotide and its conjugates were carried out in their entirety using a conventional Fmoc protocol and an autosynthesizer. The acetal was stable during the stepwise elongation of each Fmoc-amino acid as shown by the averaged coupling yield (> 95%). Octreotide (74 to 78% yield) and five conjugated derivatives were synthesized with high yields using this procedure, including three radiotherapy octreotides (62 to 75% yield) and two cellular markers (72 to 76% yield). This novel approach provides a strategy for the rapid and efficient large-scale synthesis of octreotide and its analogues for radiopharmaceutical and tagged conjugates.

Amino Acid Sequence↗
PubMed1999

[Single-pump on-line addition of modifier for supercritical fluid chromatography].

Modified CO2 as mobile phase is usually necessary for packed-column supercritical fluid chromatography. Single syringe pump was applied in this work to add modifier through a parallel connection device, which can maintain constant and stable volume fraction of modifier without any contamination of the pump. Viscosity of the modifiers (here are methanol and acetone) and the length of the CO2 pipe line/modifier pipe line can affect the volume fraction. Volume fractions of methanol and acetone were determined by gas chromatography and ultraviolet spectrometry respectively and their rules of variation were also examined. It shows that the volume fraction of methanol is lower than that of acetone under similar condition. With fixed modifierr line, the longer the CO2 line is, the higher the volume fraction will be. The new device can conveniently alter the nature and ratio of the modifier with quite stable volume fraction. The online addition device can tentatively replace the dual-pump system.

Chromatography, Supercritical Fluid↗
PubMed1997

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown (VII)].

The popularity of the base metal alloys has increased in the past decade because of their lower price, high tensile strength and high elastic modulus. Several factors are critical in ensuring successful bonding: the matching of the thermal coefficients of expansion and constraction of the porcelain and metal, the metallurgic composition of the alloy and the pretreatment procedures used in preparation of the metal substructure. Two ceramic base alloys (one alloy contains beryllium, another without) were studied. The surface textures were created by 50 microns, 100 microns aluminum oxide sandblasting, carbide bur, carborundum point and disk upon two base alloys, Rexillium III and Wiron 88. The purposes of this investigation were to determine how these variations in surface texture affect the bond strength of the two ceramo-metal alloy systems. The following results were obtained: 1. Statistics revealed that bond strength was not significantly increased with surface roughness (p > 0.05). 2. The shear bond strength for variable pretreatment methods were in the following sequence: 100 microns Al2O3 sandblasting, carbide bur, 50 microns Al2O3 sandblasting, carborundum point, disk. 3. The Rexillium III alloy had a significantly higher bond strength than Wiron 88 alloy (p < 0.05). 4. The Noritake porcelain showed a significantly higher bond strength than Biobond porcelain (p < 0.05). 5. The fracture site was cohesive and adhesive mode treated with 50 microns Al2O3, 100 microns Al2O3, carbide bur. But carborundum point and disk was adhesive mode.

Crowns↗
PubMed1996

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown the study of metal roughness and microstructure].

The metal-ceramic crown has become a predominant restoration in fixed prosthodontics. The base metal has the quality of lower price, high tensile strength, high elastic modulus. The base metal alloy that contain beryllium element increases fluidity and improved casting performance. Beryllium also controls surface oxidation and affects the metal ceramic bonds. Preparation of surface prior to porcelain bonding has been a subject of controversy among dental ceramists. Two ceramic base metal alloys (one alloy contains beryllium, another is not) were studied. This investigation evaluated the polishing effects of 50 microns, 100 microns aluminum oxide sandblasting, carbide bur, carborundum point and separating disk upon two base metal alloys, Rexillium III and Wiron 88. A scanning electron microscope was used to study the surface texture. The following results were obtained: 1. The most roughest surface was created with 50 microns aluminum oxide sandblasting. The carbide bur produced the least roughed surface. 2. There are specific surface texture patterns after polishing with five different grinding materials. 3. The metal surfaces treated with 50 microns and 100 microns aluminum oxide have same micro-structure pictures, but there are much more undercuts treated with 100 microns aluminum oxide. 4. The usage of carbide bur resulted in less undercuts of metal surface at two metal alloys. 5. The usage of carborundum point and disk resulted in abrasive particles that retained on the grinding metal surface at two metal alloys. 6. The surface of Wiron 88 alloy usually had wrinkle texture but not the Rexillium III alloy.

Crowns↗