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Biomedical subjects

Y J Zhu

Publications and source records attributed to Y J Zhu.

At least 19 recordsLinked to original sources
PubMed2004

Green fluorescent protein as a visual selection marker for papaya (Carica papaya L.) transformation.

Chemical-based selection for plant transformation is associated with a number of real and perceived problems that might be avoided through visual selection. We have used green fluorescent protein (GFP), as a visual selectable marker to produce transformed papaya ( Carica papaya) plants following microprojectile bombardment of embryogenic callus. GFP selection reduced the selection time from 3 months on a geneticin (G418) antibiotic-containing medium to 3-4 weeks. Moreover, GFP selection increased the number of transformed papaya plants by five-to eightfold compared to selection in the presence of antibiotics. Overall, the use of GFP for selecting transgenic papaya lines improved our throughput for transformation by 15- to 24-fold while avoiding the drawbacks associated with the use of antibiotic resistance-based selection markers.

Carica↗
PubMed2001

Surface chemical characterization of 2.5-microm particulates (PM2.5) from air pollution in Salt Lake City using TOF-SIMS, XPS, and FTIR.

Particulate matter with a diameter of 2.5 microm collected in Salt Lake City (SLC PM2.5) was studied using TOF-SIMS (time-of-flight secondary-ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), and FTIR (Fourier transform infrared spectroscopy). The high spatial resolution and high surface sensitivity of TOF-SIMS allow the surfaces of individual particulates to be analyzed. The high mass-resolution of TOF-SIMS provides good separation of signals from different chemical species at the same nominal mass, and the extremely high detection sensitivity of TOF-SIMS makes the detection of trace elements possible. Metallic elements such as Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Cu, Zn, Cs, and Bi were detected by TOF-SIMS on the surface of SLC PM25. The uranium ion U+ together with its oxide ions UO+ and UO2+ were also found. Inorganic compounds detected include oxides, hydroxides, nitrates, sulfates, silicates, borates, chlorides, etc. Organic compounds detected include hydrocarbons, alcohols, aldehydes, ethers, carboxylic acids, amines, amides, nitriles, etc. A number of polycyclic aromatic hydrocarbons (PAH) and nitrated polycyclic aromatic hydrocarbons were detected by TOF-SIMS. High-resolution XPS Cls spectrum shows functional groups such as C-O, CO2, C-CO2, C-C, and C-H and aromatic pi-pi* shake-up transitions. High-resolution XPS O 1s spectrum indicates the coexistence of different oxygen compounds on the surface of PM2.5. FTIR results confirm the presence of various organic compounds in SLC PM2.5 detected by TOF-SIMS and XPS.

Air Pollutants↗
PubMed2001

Effects of decreasing the frequency of ventilator circuit changes to every 7 days on the rate of ventilator-associated pneumonia in a Beijing hospital.

INTRODUCTION: We investigated whether decreasing ventilator circuit changes from every 2 days to every 7 days would impact ventilator-associated pneumonia rates at our institution. METHODS: All mechanically ventilated patients at Peking Union Medical College Hospital were studied over a 21 month period. From March 1998 to February 1999, ventilator circuits were changed every 2 days, and from June through December 1999, ventilator circuits were changed every 7 days. Nosocomial pneumonia was identified using the criteria of the Centers for Disease Control. RESULTS: In the 2-day-change group, there were 2,277 ventilator-patient days and 38 patients developed pneumonia, resulting in a pneumonia rate of 16.7 cases per 1,000 ventilator days. The 7-day-change group accumulated 972 ventilator days and 8 patients contracted pneumonia, resulting in a pneumonia rate of 8.2 cases per 1,000 ventilator days. The pneumonia rate was significantly lower in the 7-day-change group (p = 0.007). To standardize for seasonal variability, we compared results from the same seasonal time frames (June to December 1998 for the 2-day-change group, and June to December 1999 for the 7-day-change group), and obtained similar findings: during those periods, pneumonia rates were 24.2 cases per 1,000 ventilator days for the 2-day-change group and 8.9 cases per 1,000 ventilator days for the 7-day-change group (p = 0.001). CONCLUSIONS: A circuit change interval of 7 days had a lower risk of ventilator-associated pneumonia than a 2-day change interval. Therefore, ventilator circuits can be safely changed every 7 days in our setting.

Cross Infection↗
PubMed2001

[Analysis of new type composite antioxidant by HPLC/APCI-MS].

An effective method for the analysis of a new type composite antioxidant has been developed. High performance liquid chromatography (HPLC) with diode-array detection (DAD) interfaced to atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) was used. In this paper, the major components of the composite antioxidant additive were identified by means of HPLC/APCI-MS with positive/negative ion scan modes and programmable in-source collision induced dissociation and infrared(IR) spectra. The results show that this method is rapid, convenient and very useful for the analysis of lubricant additives.

English Abstract↗
PubMed2000

Fresh and nonfibrillar amyloid beta protein(1-40) induces rapid cellular degeneration in aged human fibroblasts: evidence for AbetaP-channel-mediated cellular toxicity.

Alzheimer's disease (AD) is primarily nonfamilial or sporadic (SAD) in origin, although several genetic linkages are reported. Tissues from AD patients contain fibrillar plaques made of 39 to 43 amino acid-long amyloid beta peptide (AbetaP), although the mechanisms of AbetaP toxicity are poorly understood. AbetaP(1-40) is the most prevalent AbetaP present in the neuronal and non-neuronal tissues from SAD patients. AbetaP(1-40) toxicity has been examined mainly after prolonged incubation and correlates with the age and fibrillar morphology of AbetaP(1-40). Globular and nonfibrillar AbetaPs are released continually during normal cellular metabolism; they elevate cellular Ca(2+) and form cation-permeable channels. However, their role in cellular toxicity is poorly understood. We have used an integrated atomic force and light fluorescence microscopy (AFM-LFM), laser confocal microscopy, and calcium imaging to examine real-time and acute effect of fresh and globular AbetaP(1-40) on cultured, aged human, AD-free fibroblasts. AFM images show that freshly prepared AbetaP(1-40) in phosphate-buffered saline (PBS) are globular and do not form fiber for an extended time period. AbetaP(1-40) induced rapid structural modifications, including cytoskeletal reorganization, retraction of cellular processes, and loss of cell-cell contacts, within minutes of incubation. This led to eventual cellular degeneration. AbetaP(1-40)-induced degeneration was prevented by anti-AbetaP antibody, zinc, and Tris, but not by tachykinin neuropeptides. In Ca(2+)-free extracellular medium, AbetaP(1-40) did not induce cellular degeneration. In the presence of extracellular Ca(2+), AbetaP(1-40) induced a sustained increase in the cellular Ca(2+). Thus, short-term and acute AbetaP(1-40) toxicity is mediated by Ca(2+) uptake, most likely via calcium-permeable AbetaP pores. Such rapid degeneration does not require fibrillar plaques, suggesting that the plaques may not have any causative role.

Alzheimer Disease↗
PubMed2000

Effects of inhaled low molecular weight heparin on airway allergic inflammation in aerosol-ovalbumin-sensitized guinea pigs.

Low molecular weigh, heparin (LMWH) possesses multiple nonanticoagulant properties. In the present study, we observed its anti-airway allergic inflammatory effects by bronchoalveolar lavage in guinea pigs. Guinea pigs were sensitized by repeatedly inhaling aerosolized ovalbumin. LMWH (400 u/l, 800 u/l), dexamethasone (1.2 mg/1) or vehicle (normal saline) was inhaled for 7 days. Then the animals were sacrificed under anesthesia and then lavaged with ice-cold Hank's buffer immediately; bronchoalveolar lavage fluid (BALF) was prepared 24 h after the animals were challenged by antigen exposure. The effects of LMWH on total cell counts, absolute eosinophil counts and cell catalogues in BALF were studied; effects on the activity of eosinophil peroxidase (EPO) and the contents of histamine and eosinophil cationic protein (ECP) in BALF supernatant were detected. Our results showed that compared with the vehicle group, LMWH at 400 u/l and 800 u/1 could significantly reduce total cell counts, absolute eosinophil counts and percentage of eosinophils in BALF (P<0.05 and P<0.01, respectively); LMWH at 800 u/l markedly inhibited the activity of EPO in BALF supernatant (P<0.05); LMWH at 400 u/l and 800 u/l remarkably reduced the content of histamine in BALF supernatant (P<0.05 and P<0.01, respectively), LMWH at 800 u/l decreased the content of ECP (P<0.05) significantly. It suggested that LMWH exerted anti-airway allergic inflammatory action by inhibiting infiltration of inflammatory cells and reducing release of inflammatory mediators, as well as antagonizing their activities, and that LMWH could be developed as a potential anti-bronchial asthmatic drug.

Administration, Inhalation↗
PubMed1999

Amyloid beta protein (1-40) forms calcium-permeable, Zn2+-sensitive channel in reconstituted lipid vesicles.

Amyloid beta protein (A beta P) forms senile plaques in the cerebrocortical blood vessels and brain parenchyma of patients with Alzheimer's disease (AD). The nonfamilial or sporadic AD (SAD), the most prevalent form of AD, has been correlated with an increased level of 40-residue A beta P (A beta P1-40). However, very little is known about the role of A beta P1-40 in AD pathophysiology. We have examined the activity of A beta P1-40 reconstituted in phospholipid vesicles. A combined light fluorescence and atomic force microscope (AFM) was used to image the structure of reconstituted vesicles and 45Ca2+ uptake was used as an assay for calcium permeability across the vesicular membrane. Vesicles reconstituted with fresh and globular A beta P1-40 contain a significant amount of A0 beta P and exhibit strong immunofluorescence labeling with an antibody raised against the N-terminal domain of A beta P, suggesting the incorporation of A beta P1-40 peptide in the vesicular membrane. Vesicles reconstituted with A beta P1-40 exhibited a significant level of 45Ca2+ uptake. The vesicular calcium level saturated over time, showing an important ion channel characteristic. The 45Ca2+ uptake was inhibited by (i) a monoclonal antibody raised against the N-terminal region of A beta P and (ii) Zn2+. However, a reducing agent (DTT) did not inhibit the 45Ca2+ uptake, indicating that the oxidation of A beta P or its surrounding lipid molecules is not directly involved in A beta P-mediated Ca2+ uptake. These findings provide biochemical and structural evidence that fresh and globular A beta P1-40 forms calcium-permeable channels and thus may induce cellular toxicity by regulating the calcium homeostasis in nonfamilial or sporadic Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1998

Effects of tetramethylpyrazine, a Chinese medicine, on plasma endothelin-1 levels during acute pulmonary hypoxia in anesthetized dogs.

Our study was designed to elucidate the effects of tetramethylpyrazine (TMP), a Chinese medicine, on plasma endothelin-1 (ET-1) levels in dogs with acute pulmonary alveolar hypoxia. Anesthetized dogs were used under artificial ventilation with room air or a hypoxic gas mixture (10% O2 and 90% N2) (n = 10) for 60 min. Effects of TMP (80 mg/kg) were studied by i.v. injection of TMP before exposure to hypoxia (n = 8). Mean pulmonary arterial pressure (PAPm), systemic arterial pressure (SAPm), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and heart rate (HR) were measured. The pulmonary vascular resistance (PVR) was calculated by the equation of (PAPm-PCWP) x 8/CO. Plasma ET-1 levels were determined in the abdominal aorta and pulmonary artery by RIA. The effects of TMP on PAP and plasma ET-1 level were evaluated by using percent increase in PAPm and the change of Da-pET (delta ET) before and after hypoxia. Both PAPm and PVR were significantly elevated 5 min after acute hypoxia over a period of 60 min, whereas CO and PCWP did not change. Plasma ET-1 levels in the abdominal aorta and Da-pET showed a significant increase. Administration of TMP significantly decreased the hypoxia-induced increase in the PAPm, PVR, and delta ET. These results suggest that TMP could be a useful therapeutic agent in the treatment of pulmonary hypertension induced by acute hypoxia through decrease of plasma ET-1 levels.

Anesthesia, General↗
PubMed1997

Wild-type p53 gene increases MDR1 gene expression but decreases drug resistance in an MDR cell line KBV200.

Inactivation of p53 gene and overexpression of MDR1 gene are both associated with drug resistance. Previous studies have suggested that p53 gene can modulate the expression activity of MDR1 gene promoter in a promoter-CAT system. In the present study, wild-type p53 gene cDNA was introduced into a multidrug-resistant cell line, KBv200, in which endogenous p53 gene is aberrant. In wt-p53 transfected cells, the expression of MDRI gene was significantly increased, accumulation of adriamycin (ADM) was decreased, and the sensitivity to vincristine (VCR), ADM and 5-fluorouracil (5-FU) was increased compared with the parent KBv200 cells. After treatment with ADM and VCR, the p53-transfectants were more susceptible to apoptosis. The results suggest that the increase in drug sensitivity of the cells may be, at least in part, due to p53-dependent apoptosis induced by anticancer agents.

Drug Resistance, Multiple↗
PubMed1997

Strained DNA is kinked by low concentrations of Zn2+.

A novel atomic force microscope with a magnetically oscillated tip has provided unprecedented resolution of small DNA fragments spontaneously adsorbed to mica and imaged in situ in the presence of divalent ions. Kinks (localized bends of average angle 78 degrees) were observed in axially strained minicircles consisting of tandemly repeated d(A)5 and d(GGGCC[C]) sequences. The frequency of kinks in identical minicircles increased 4-fold in the presence of 1 mM Zn2+ compared with 1 mM Mg2+. Kinking persisted in mixed Mg2+/Zn2+ electrolytes until the Zn2+ concentration dropped below 100 microM, indicating that this type of kinking may occur under physiological conditions. Kinking appears to replace intrinsic bending, and statistical analysis shows that kinks are not localized within any single sequence element. A surprisingly small free energy is associated with kink formation.

Base Sequence↗
PubMed1997

Protective role of selenium against hepatitis B virus and primary liver cancer in Qidong.

High rates of hepatitis B virus (HBV) infection and primary liver cancer (PLC) are present in Qidong county. Epidemiological surveys demonstrated an inverse association between selenium (Se) level and regional cancer incidence, as well as HBV infection. Four-year animal studies showed that dietary supplement of Se reduced the HBV infection by 77.2% and liver precancerous lesion by 75.8% of ducks, caused by exposure to natural environmental etiologic factors. An intervention trial was undertaken among the general population of 130,471. Individuals in five townships were involved for observation of the preventive effect of Se. The 8-yr follow-up data showed reduced PLC incidence by 35.1% in selenized table salt supplemented vs the nonsupplemented population. On withdrawal of Se from the treated group, PLC incidence rate began to increase. However, the inhibitory response to HBV was sustained during the 3-yr cessation of treatment. The clinical study among 226 Hepatitis B Surface Antigen (HBsAg)-positive persons provided either 200 micrograms of Se in the form of selenized yeast tablet or an identical placebo of yeast tablet daily for 4 yr showed that 7 of 113 subjects were diagnosed as having PLC in the placebo group, whereas no incidence of PLC was found in 113 subjects supplemented with Se. Again on cessation of treatment, PLC developed at a rate comparable to that in the control group, demonstrating that a continuous intake of Se is essential to sustain the chemopreventive effect.

Adult↗
PubMed1997

[Reversal of multidrug resistance by cyproheptadine in KBV200 cells].

The cyproheptadine (CYP) reversal of multidrug resistance (MDR) and its mechanism in KBV200 cell line were studies. MTT assay showed that CYP 15.0 mumol.L-1 could reverse vincristine, adriamycin (ADR) and etoposide resistance in KBV200 cells by a factor of 5.5, 2.0 and 1.9, respectively. CYP appeared to have no influence on the cytotoxicity of 5-fluorouracil (5-FU) and melphalan (MEL) in the cells. These results indicate that CYP is a MDR reversing agent. CYP 15.0 mumol.L-1 increased the ADR accumulation in KBV200 cells from 0.68 +/- 0.03 microgram/10(6) cells to 1.36 +/- 0.08 micrograms/10(6) cells (P < 0.01). CYP 15.0 mumol.L-1 was shown to obviously increase rhodamine 123 (R123) accumulation in and decrease its efflux from the cells. There was no change in PGP dying intensity under immunocytochemical assay and in mdr1 RNA level through slot blot analysis in the KBV200 cells exposed continuously to CYP 15.0 mumol.L-1 for 72 h. These results suggest that CYP acts by inhibiting the pumping function of PGP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Wild-type p53 stimulates vincristine-induced apoptosis].

Recent studies indicate that wild-type p53 can trigger cell apoptosis induced by many chemotherapeutic agents which induce DNA damage or cause disruptions of DNA metabolism, such as ADM, 5-FU, VP-16 and radiation. We introduced the wild-type p53 gene into a MDR cell line KBV200 in which the endogenous p53 was found to be rearranged. By G418 selection and Northern blot analysis, a G418-resistant clone named KBV200-p53 was obtained which continuously expressed the exogenous wild-type p53 mRNA. After treatment with Vincristine(VCR), the wild type p53-expression cells presented typical morphology characteristic of apoptosis analysed under electron and fluorescence microscopes. Flow cytometer analysis showed that the KBV200-p53 cells were more readily undergo apoptosis than their parental cells KBV200. After treatment with VCR 600 nmol.L-1 for 24 h, the apoptotic percentage of KBV200-p53 and KBV200 cells was about 42.4% and 8.4%, respectively. This result indicates that wild-type p53 stimulates VCR-induced apoptosis in KBV200 cells.

Antineoplastic Agents, Phytogenic↗
PubMed1994

[Clinical analysis of 60 cases of nosocomal pneumonias].

This article gives a clinical analysis upon 60 cases of nosocomial acquired pneumonia. All the patients are > 18 years old and the onset time ranged from 3 to 180 days after they were hospitalized with an average of 38.77 days, mostly 30 days after admission (27 cases, 49%). Among the primary diseases, the hematologic disorder (18 cases, 30%) rank the first, followed by cerebrovascular disease (9 cases, 15%) and connective tissue disease (8 cases, 13.3%), The common inducing factors are the using of corticosteroids and chemotherapy (34 cases, 58%), tracheotomy and tracheal cannula (7 cases, 11.6%). Fever occurs in 96% of the patients and cough 63.3%. The positive rate of sputum bacterial culture is 95.46%. Pseudomonas aeruginosa isolated in 25 cases (56.8%). and Klebsiella pneumoniae 18 cases (40%). P. aeruginosa shows resistant to the third generation of cefalosporins more than before, and is sensitive to ciprofloxacin and polymyxin B, while K. pneumoniae is resistant to many kinds of antibiotics, especially ampicilline and carbenicilline. The death rate of infection of P. aeruginosa is 58.33% (14/25) and that of K. pneumoniae is 60% (12/18), that of mixed infection is 66.67% (16/23).

Adult↗
PubMed1994

[Pulmonary nocardia infection].

Four cases of pulmonary Nocardia infection were reported and the 22 cases reported in our country between 1980 and 1993 were analyzed together for the purpose of revealing the clinical picture of this disease in China. There was approximately a ratio of two male patients to one female (18:8) with a mean age of 40 years in this series of patients. Various underlying diseases were found as predisposing factors in 69% (18/26) of the cases. 34.5% (9/26) of the cases had a history of corticosteroid therapy. Pleural effusion was identified in 50% (13/26) of the patients. 38% (10/26) of the patients died. Patients with primary pulmonary Nocardia infection had a better prognosis than those with secondary infection. Appropriate culture media, sufficient culture time and repeated cultures were recommended to improve the positive identification rate of this special causative agent. The sulfonamides were the drugs of first choice along with prompt drainage of thoracic empyema and abscess.

Adult↗