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Y H Liu

Publications and source records attributed to Y H Liu.

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

Direct layer-by-layer freezing of a smectic liquid-crystal surface into the crystalline phase.

Electron diffraction and optical reflectivity have provided the direct confirmation of the existence of layer-by-layer surface transitions from the smectic-A immediately to the crystal-B phase in a liquid-crystal material, without going through an intermediate hexatic phase. The molecular interactions are found to be through retarded van der Waals forces. Our results suggest that a smectic-A film can transform into a crystal-B through three possible scenarios.

Journal Article↗
PubMed2001

Colonoscopy in mice.

INTRODUCTION: Current investigational models of murine colitis and colon cancer necessitate sacrifice of animals in order to obtain colonic tissue. The purpose of this study was to develop a safe method of murine colonoscopy that would allow serial evaluation and mucosal biopsies of the same animal. METHODS: Nine mice (two C3H, two C57/BL6, and five IL-10 deficient) were studied a total of four times each over 4 weeks. Three mice [APC (Min +/-)] were examined three times each. Mice were gavaged with 1 cc of a polyethylene glycol solution on the day prior to colonoscopy. Solid chow was withheld and the mice were maintained on Pedialyte. Mice were anesthetized with ketamine and xylazine. A flexible pediatric cystoscope (2.1-mm diameter) with a single biopsy channel was introduced per anum, and the colon was gently insufflated with air to a mean pressure of less than 5 mmHg. Saline irrigation was used when necessary. A single biopsy was obtained from the rectosigmoid colon during each examination. RESULTS: A total of 46 examinations were carried out. One mouse died after being anesthesized for the fourth examination, and two mice [one IL-10 knockout and one APC (Min+/-)] died one day after the 3rd examination. No other complications were noted. The average length of insertion was 3 cm. Transillumination allowed for localization of the endoscope tip. Biopsies, although quite small, were sufficient for pathologic evaluation and diagnosis. CONCLUSIONS: Murine colonoscopy is a safe and feasible technique. It permits consecutive visual and histopathological examinations, and it allows the investigator to monitor the response of the murine colon to experimental interventions.

Animals↗
PubMed2001

Empty capsids in column-purified recombinant adenovirus preparations.

Empty capsids from adenovirus, that is, virus particles lacking DNA, are well documented in the published literature. They can be separated from complete virus by CsCl density gradient centrifugation. Here we characterize the presence of empty capsids in recombinant adenovirus preparations purified by column chromatography. The initial purified recombinant adenovirus containing the p53 tumor suppressor gene was produced from 293 cells grown on microcarriers and purified by passage through DEAE-Fractogel and gel-filtration chromatography. Further sequential purification of the column-purified virus by CsCl and glycerol density gradient centrifugations yielded isolated complete virus and empty capsids. The empty capsids were essentially noninfectious and free of DNA. Analysis of empty capsids by SDS-PAGE or RP-HPLC showed the presence of only three major components: hexon, IIIa, and a 31K band. This last protein was identified as the precursor to protein VIII (pVIII) by mass spectrometric analysis. No pVIII was detected from the purified complete virus. Analysis by electron microscopy of the empty capsids showed particles with small defects. The amount of pVIII was used to determine the level of empty capsid contamination. First, the purified empty capsids were used to quantify the relation of pVIII to empty capsid particle concentration (as estimated by either light scattering or hexon content). They were then used as a standard to establish the empty capsid concentration of various recombinant adenovirus preparations. Preliminary research showed changes in empty capsid concentration with variations in the infection conditions. While virus purification on anion-exchange or gel-filtration chromatography has little effect on empty capsid contamination, other chromatographic steps can substantially reduce the final concentration of empty capsids in column-purified adenovirus preparations.

Adenoviridae↗
PubMed2001

[Effect of peritonitis pathomorphology on rabbit model in peritoneal dialysis].

The study about peritonitis rabbit model is rarely, although peritonitis have been considered mainly complication in peritoneal dialysis. Twelve New Zealand rabbit were divided into peritonitis group and control group. The peritonitis group rabbit were injected with the dialysate containing alive staphylococcus aureus and the control ones with 0.9% saline into the peritoneum. The pathomorphology changes of the peritonitis were observed. The results showed (1) There was proliferation and swollen of mesothelial cells, vessel dilation and infiltration of inflammation cells in the peritoneum in the peritonitis group; and no such changes in the control group. (2) The D/D0 glucose concentration in the dialysate of peritonitis group was lower than that of the control ones at any point except the 0 min (P < 0.01). (3) The ratio of Cr concentration in the dialysate to Cr concentration in the plasma in the peritnitis group was significantly higher than that of the control group (P < 0.05). (4) The WBC count in the dialysate of peritonitis group was obviously higher than that of the control group all points except 0. These results implied that after injection of alive staphylococcus aureus to the peritoneal cavity of New Zealand rabbit for 48 hours, the pathomorphology change was similar with the characteristics of peritonitis complicated with peritoneal dialysis in patient.

Animals↗
PubMed2001

Long-term effect of N-acetyl-seryl-aspartyl-lysyl-proline on left ventricular collagen deposition in rats with 2-kidney, 1-clip hypertension.

BACKGROUND: N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a natural inhibitor of pluripotent hematopoietic stem cell proliferation. Ac-SDKP plasma concentration is increased 5-fold after angiotensin-converting enzyme inhibition. Here we studied the effect of Ac-SDKP on monocyte/macrophage infiltration, fibroblast proliferation, and collagen deposition in the rat heart in renovascular hypertension. METHODS AND RESULTS: We investigated whether long-term Ac-SDKP administration would prevent left ventricular (LV) hypertrophy and interstitial collagen deposition in rats with 2-kidney, 1-clip (2K-1C) hypertension. Ac-SDKP (400 microgram. kg(-1). d(-1)) did not affect development of hypertension. Mean blood pressure was similar in rats with 2K-1C hypertension whether they were given vehicle or Ac-SDKP and was higher than in controls. Both LV weight and cardiomyocyte size were significantly increased in rats with 2K-1C hypertension compared with controls and were unaffected by Ac-SDKP. Proliferating cell nuclear antigen- and monocyte/macrophage-positive cells were increased in the LV of 2K-1C hypertensive rats; this increase was significantly blunted by Ac-SDKP (P<0.001). LV interstitial collagen fraction was also increased in 2K-1C hypertensive rats given vehicle (10.1+/-0.8%) compared with sham (5.3+/-0.1%, P<0.0001), and this increase was prevented by Ac-SDKP (5.4+/-0.4%, P<0.001). CONCLUSIONS: Ac-SDKP inhibited monocyte/macrophage infiltration, cell proliferation, and collagen deposition in the LV of hypertensive rats without affecting blood pressure or cardiac hypertrophy, suggesting that it may be partly responsible for the cardioprotective effect of angiotensin-converting enzyme inhibitors.

Animals↗
PubMed2001

Diminished cardioprotective response to inhibition of angiotensin-converting enzyme and angiotensin II type 1 receptor in B(2) kinin receptor gene knockout mice.

Using B(2) kinin receptor gene knockout mice (B(2)(-/-)), we tested the hypothesis that (l) lack of B(2) receptors may affect blood pressure and cardiac function and aggravate cardiac remodeling after myocardial infarction (MI), and (2) kinins partially mediate the cardiac beneficial effect of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II type 1 receptor antagonists (AT(1)-ant), whereas lack of B(2) receptors may diminish this cardioprotective effect. Chronic heart failure (HF) was induced by MI, which was caused by coronary artery ligation in both B(2)(-/-) and 129/SvEvTac mice (wild-type control, B(2)(+/+)). An ACEi (ramipril, 2.5 mg/kg/d) or AT(1)-ant (L-158809, 3 mg/kg/d) was given 1 week after MI and was continued for 12 weeks. Left ventricular (LV) ejection fraction, cardiac output (CO), diastolic LV dimension (LVDd), and LV mass were evaluated by echocardiography. Myocyte cross-sectional area and interstitial collagen fraction were studied histopathologically. We found that basal blood pressure and cardiac function were similar in B(2)(+/+) and B(2)(-/-) mice. After MI, development of HF and remodeling were also similar between the 2 strains. The ACEi improved cardiac function and remodeling in both strains; however, its effects were attenuated in B(2)(-/-) mice (respective values for B(2)(+/+) versus B(2)(-/-) mice: overall increase in ejection fraction, 64+/-10% versus 21+/-5% [P<0.01]; increase in CO, 69+/-17% versus 23+/-9% [P<0.01]; overall decrease in LVDd, -24+/-3% versus -7+/-4% [P<0.01]; and decrease in LV mass, -38+/-3% versus -6+/-6% [P<0.01]). AT(1)-ant had a beneficial cardiac effect similar to that produced by ACEi, and this effect was also diminished in B(2)(-/-) mice (respective values for B(2)(+/+) versus B(2)(-/-) mice: overall increase in ejection fraction, 46+/-10% versus 25+/-9% [P<0.01]; increase in CO, 44+/-14% versus 15+/-5% [P<0.01]; overall decrease in LVDd, -14+/-4% versus -6+/-3% [P<0.01]; and decrease in LV mass, -33+/-4 versus -16+/-7% [P<0.01]). The effect of ACEi or AT(1)-ant on myocyte cross-sectional area was similar between strains; however, their effect on the interstitial collagen fraction was diminished in B(2)(-/-) mice. We concluded that (1) lack of B(2) kinin receptors does not affect cardiac phenotype or function, either under normal physiological conditions or during the development of HF; and (2) kinins acting via the B(2) receptor play an important role in the cardioprotective effect of ACEi and AT(1)-ant.

Angiotensin Receptor Antagonists↗
PubMed2001

Unusual thickness-dependent thermal behavior and anticlinic coupling in chiral smectic free-standing liquid-crystal films.

We observe, in free-standing films of a chiral smectic liquid crystal, a series of discrete transitions in the relative orientation of the tilt of the interior and surface layers. These transitions include a remarkable reentrant synclinic-anticlinic-synclinic ordering sequence of the film surfaces in the presence of an electric field upon cooling. The profiles of the associated heat-capacity anomalies are found to be strongly thickness dependent and exhibit a novel crossover behavior in reduced dimensions. We measure the anticlinic coupling between tilted surface layers in the smectic- A phase.

Journal Article↗
PubMed2001

Association of bovine papillomavirus type 1 with microtubules.

Transport of BPV-1 virus from the cell membrane to the nucleus was studied in vitro in CV-1 cells. At reduced temperature (4 degrees C), BPV-1 binding to CV-1 cells was unaffected but there was no transport of virions across the cytosol. Electron microscopy showed BPV-1 virions in association with microtubules in the cytoplasm, a finding confirmed by co-immunoprecipitation of L1 protein and tubulin. Internalization of virus was unimpaired in cells treated with the microtubule-depolymerizing drug nocodazole but virions were retained in cytoplasmic vesicles and not transported to the nucleus. We conclude that a microtubule transport mechanism in CV-1 cells moves intact BPV-1 virions from the cell surface to the nuclear membrane.

Active Transport, Cell Nucleus↗
PubMed2001

Catalytic asymmetric coupling of 2-naphthols by chiral tridentate oxovanadium (IV) complexes.

A series of chiral oxovanadium(IV) complexes derived from tridentate N-3,5-substituted and N-3,4-benzo- and N-5,6-benzo-salicylidene-alpha-amino acids can serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, and 7-substituted 2-naphthols under O(2). The best scenario involves the use of a vanadyl complex arising from 2-hydroxy-1-naphthaldehyde and valine (or phenylalanine) in CCl(4), leading to BINOLs in good yields (75-100%) and with enantioselectivities of up to 68%.

Journal Article↗
PubMed2001

Syntheses of chromium pentacarbonyl derivatives of arsenic(V) and antimony(V). contrasting chemical reactivity with organic halogen derivatives.

We have synthesized a new series of chromium-group 15 dihydride and hydride complexes [H(2)As(Cr(CO)(5))(2)](-) (1) and [HE(Cr(CO)(5))(3)](2)(-) (E = As, 2a; E = Sb, 2b), which represent the first examples of group 6 complexes containing E-H fragments. The contrasting chemical reactivity of 2a and 2b with organic halogen derivatives is demonstrated. The reaction of 2a with RBr (R = PhCH(2), HC triple bond CCH(2)) produces the RX addition products [(R)(Br)As(Cr(CO)(5))(2)](-) (R = PhCH(2), 3; R = C(3)H(3), 4), while the treatment of 2b with RX (RX = PhCH(2)Br or HC triple bond CCH(2)Br, CH(3)(CH(2))(5)C(O)Cl) forms the halo-substituted complexes [XSb(Cr(CO)(5))(3)](2-) (X = Br, 5; X = Cl, 6). Moreover, the dihaloantimony complexes [XX'Sb(Cr(CO)(5))(2)](-) can be obtained from the reaction of 2b with the appropriate organic halides. In this study, a series of organoarsenic and antimony chromium carbonyl complexes have been synthesized and structurally characterized and the role of the main group on the formation of the resultant complexes is also discussed.

Journal Article↗
PubMed2001

Increased fetal nuchal fold leading to prenatal diagnosis of ring chromosome 15.

We report on the prenatal diagnosis of ring chromosome 15 in a fetus with increased nuchal fold and intrauterine growth restriction (IUGR). A 27-year-old woman gravida 2, para 1 had normal maternal serum screen tests in the early second trimester of the index pregnancy. Fetal nuchal fold thickening up to 8 mm was incidentally found during the routine obstetric ultrasound scan at 20 weeks' gestation. Amniocentesis was undertaken and the fetal karyotype was found to be 46,XY,r(15) on cytogenetic study. Fluorescence in situ hybridization (FISH) using a telomeric probe of chromosome 15 demonstrated a terminal deletion on the q arm of the ring-shaped chromosome 15. This is the first report of a prenatally diagnosed case of ring chromosome 15. Moreover, nuchal fold thickness in the second trimester may have a role in its prenatal diagnosis.

Abortion, Induced↗
PubMed2001

Preimplantation genetic diagnosis (PGD), a collaborative activity of clinical genetic departments and IVF centres.

Preimplantation genetic diagnosis (PGD) requires the combined efforts of geneticists and workers in the field of reproductive medicine. This was studied on the basis of a questionnaire, sent to 35 members of the PGD Consortium of the European Society of Human Reproduction and Embryology (ESHRE). A reply was obtained from 20 centres. They represent the majority of activities in the field of PGD in the world. It is obvious that many of the activities (in vitro fertilisation, embryo culture and biopsy) take place in IVF units while others (counselling and diagnosis) are the responsibility of genetic diagnostic centres. The distances between both units vary considerably. In all but one centre sex determination is offered. Aneuploidy screening is offered in 13 out of 20 centres. PGD of translocations and other structural chromosome abnormalities is offered in all but one centre. The number of monogenic diseases offered varies considerably. In comparison to prenatal diagnosis PGD is more expensive. The majority of these costs are due to the IVF or ICSI procedure. The charges for PGD vary between about 600 euro and 4000 euro. In 16 out of 20 centres the parents to be must sign an informed consent form.

Aneuploidy↗
PubMed2001

Minimal access thoracic surgery for esophageal hemangioma.

Esophageal hemangioma is a rare tumor. This report describes the case of a 69-year-old woman with an esophageal tumor at the middle portion of the esophagus. The patient was successfully treated with minimal access thoracic surgery, and at the 6 month follow-up, the patient was free of any symptoms or recurrence.

Aged↗
PubMed2001

Structural correlation of catecholase-like activities of oxy-bridged dinuclear copper(II) complexes.

Eight oxy-bridged dinuclear copper(II) complexes with catecholase-like sites, [Cu(L1)X]2 (HL1 = 1-diethylaminopropan-2-ol, X=N3- 1, NCO- 2, and NO2- 3), [Cu(L2)X]2 (HL2=N-ethylsalicylaldimine, X=NO3- 4, Cl- 5, N3- 6, NCS- 7), and [Cu(L3)]2(ClO4)2, 8 (HL3=N-(salicylidene)-N'-(2-pyridylaldene)propanediamine) have been prepared and characterized. The single crystal X-ray analysis show that the structures of complexes 6 and 8 are dimeric with two adjacent copper(II) atoms bridged by pairs of micro-oxy atoms from the L2 and L3 ligands. Magnetic susceptibility measurements in the temperature range 4-300 K indicate significant antiferromagnetic coupling for 4, 5 and 7 and ferromagnetic coupling for 6 between the copper(II) atoms. The catecholase activity of complexes for the oxidation of 3,5-di-tert-butylcatechol by O2 was studied and it was found that the complexes with the bond distance of Cu(II)...Cu(II) located at 2.9-3.0 A show higher catecholase activity.

Catalytic Domain↗
PubMed2001

Carboxyalkylated histidine is a pH-dependent product of pegylation with SC-PEG.

PURPOSE: Pegylation of therapeutic protein usually results in a mixture of monopegylated proteins with differing sites of modification. With rh-interferon-alpha2A pegylation, we have found that this heterogeneity includes two classes of pegylation site chemistry, the relative proportions of which can be adjusted by reaction pH. METHODS: The effect of pegylation reaction pH on the relative proportion of three peaks produced was investigated. Products were purified and characterized by peptide mapping, chemical stability to neutral hydroxylamine, and biologic activity. RESULTS: Reactions at basic pH levels produced a mixture of products pegylated at lysine residues as has been observed elsewhere. However, the dominant product of reactions at mildly acidic levels of pH showed distinct chemistry and higher cytopathic effect activity. The primary site of modification at this pH was His34. We developed a quantitative assay using sensitivity to neutral hydroxylamine to measure the proportion of urethane bonds involving carboxyalkylated histidines. This assay showed that histidine was pegylated preferentially at low pH levels with another protein, rh-Interleukin-10. CONCLUSIONS: Reaction pH can be used to select the preferred pegylation site chemistry.

Alkylation↗
PubMed2001

Comparisons of the cost-effectiveness among hospital chronic care, nursing home placement, home nursing care and family care for severe stroke patients.

AIM: This study compared the cost and effectiveness of long-term institutional care and home care for stroke patients with severe physical disabilities. BACKGROUND: Whether home care is more economical or effective than institutional care for patients with chronic illnesses remains controversial when the cost of family labour is considered. Thus, decisions concerning the appropriate type of care setting for patients with severe chronic illness remain difficult. METHODS: From November 1995 to March 1996, 313 hospitalized stroke patients with severe physical disabilities treated at one of five hospitals in the Taipei metropolitan area were followed from the day of hospital discharge until the third month after discharge. These 313 patients were divided into four groups as follows: (1) 106 who were admitted to a chronic care unit in a hospital, (2) 60 who were admitted to nursing homes, (3) 60 who received professional home nursing care and (4) 87 who returned home without receiving professional care. The change of physical functional status in the patient was examined as the difference between activities of daily living (ADL) scores measured at discharge and at the end of the third month after discharge. RESULTS: Information on family costs for caregiving, including pay for long-term services utilized, labour costs for caregiving and out-of-pocket expenditures for miscellaneous materials was obtained during a weekly telephone interview. The results indicated that caring for patients in their own homes was not only more expensive but was also less effective in improving ADL scores than caring for patients in nursing homes and in chronic care units of hospitals. CONCLUSIONS: The results suggest that caring for patients with severe physical disabilities in institutions is more appropriate than caring of them at home.

Activities of Daily Living↗
PubMed2001

Alternate methods for laparoscopic management of adnexal masses greater than 10 cm in diameter.

PURPOSE: We describe alternate laparoscopic methods for inspection and removal of large adnexal masses, and report our experience with 18 cases in which these methods were used. PATIENTS AND METHODS: Between April 1994 and January 2000, the first author performed operative laparoscopy on 18 patients, each of whom had at least one adnexal mass with maximum diameter greater than 10 cm. Mean patient age was 32 years (range 11 to 82). Seventeen of the 18 patients were premenopausal. All procedures were performed at one of two community hospitals in Seattle or at Yuan's General Hospital in Taiwan. Preoperative screening included pelvic exam, tumor markers, and ultrasound. RESULTS: One 82-year-old patient underwent planned laparoscopic bilateral oopherectomy. In the other 17 cases the operative goal was cystectomy or unilateral oopherectomy with conservation of reproductive function. Cystectomy was successfully performed in five of these cases (29.4%). The remaining 12 patients underwent either unilateral oopherectomy (10 cases, 58.8%), or unilateral salpingo oopherectomy (2 cases, 8.8%) due to the extent of their mass. Sixteen of the 18 cases in this series were successfully managed by a single laparoscopic surgery, one case required a second-look laparoscopy, and in one case a malignancy was found by histological analysis of permanent section, which required a second laparoscopy for staging and debulking. CONCLUSIONS: Large adnexal masses can be successfully managed with minimal hospital stay using laparoscopic techniques, when care is taken to avoid rupture and spillage of cyst contents, and thorough inspection of the mass and abdominal cavity is made possible. The probability of finding an unexpected malignancy is low. In those cases where a malignancy is found, appropriate cytoreductive staging surgery can be performed immediately.

Adolescent↗