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Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 199 records · Page 11Linked to original sources
PubMed2001

Dexamethasone modulation on cultured human retinal pigment epithelial cell.

PURPOSE: Dexamethasone(DEX) was tested for its ability to modulate human retinal pigment epithelium(hRPE) cell proliferation in cell culture. METHODS: DEX in different concentrations was added to cultured hRPE cells. The effects were measured with MTT method, 3H-thymidine(3H-TdR) incorporation and flow cytometry. RESULTS: DEX increased survival rate and DNA synthesis from 32 mg/L to 320 mg/L under hRPE culture conditions, but paradoxically reduced them at 1,000 mg/L and 3,200 mg/L in dose and time dependent fashion by both MTT assay and 3H-TdR incorporation. The cell numbers in S phase and G2/M phase increased 28.32% at DEX concentration 320 mg/L, in contrast, reduced 41.84% at 1,000 mg/L. CONCLUSION: DEX increased proliferation from 32 mg/L to 320 mg/L, and inhibited proliferation at concentrations greater than 320 mg/L. The inhibiting effect of DEX may happen in s phase and G2/M phase.

Anti-Inflammatory Agents↗
PubMed2001

[Observation on eggs of Oncomelania hupensis hupensis with scanning electron microscope].

OBJECTIVE: To observe the structure of the mud hull packed Oncomelania eggs and the surface structure of colloid membrane called the third grade membrane of eggs. METHODS: Scanning electron microscopy was used to observe Oncomelania snail eggs with integral mud hull collected from eastern Dongting Lake. RESULTS AND CONCLUSION: The mud hull of eggs was made of unshapen small humification combined with earth granules with a diameter of 2.6-9.2 microns. The mud hull in 60 um thickness was honeycomb-like in shape with many small holes and small folds on the wall. There were many round or irregularly round hollownesses on the inner layer of mud hull that contacts colloid membrane but no hole through mud hull. There were some protein fiber networks covering on the colloid membrane and apophysis. The structure of the mud hull showed that the exchange of matter was maintained between eggs and outside, and the mud hull is of great importance to regulating temperature and moisture for the growth of eggs by preventing hydrosoluble substances from penetrating into eggs. The protein fiber networks act on gluing mud hull and buffering outside power. The dense glue membrane might be a main barricade to prevent pharmaceutical molecules from penetrating into eggs.

Animals↗
PubMed2001

[Effect of estrogen on dopamine release evoked by electric stimulation of central amygdaloid nucleus].

In vivo fast cyclic voltammetry (FCV) was used to investigate dopamine (DA) release from central amygdaloid nucleus (CAN) of ovariectomized (OVX), estrogen-treated and normal female rats. Radioimmunoassay was used to measure the serum concentration of estradiol (E(2)). DA release was significantly higher in OVX rats treated with estradiol benzoate (EB) as compared with controls. The DA release due to electric stimulation is dose-dependent on serum concentration of estradiol, suggesting that estrogen may play an important role in regulating DA release from CAN.

Amygdala↗
PubMed2001

[Apolipoprotein C III gene Sst I polymorphism in patients with endogenous hypertriglyceridemia in Chinese population].

OBJECTIVE: To investigate the apoC III gene Sst I polymorphism and its relationship with serum lipids and apolipoproteins (apo) levels in patients with endogenous hypertriglyceridemia in Chinese population. METHODS: The genotype and allele frequency of apoC III gene Sst I polymorphism was assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits and apolipoproteins A I, A II, B100, C II, C III and E were measured by RID kits developed by Apolipoprotein Research Unit of WCUMS in 176 HTG patients whose fasting serum TG levels were > or = 2.26 mmol/L and in 199 healthy subjects whose fasting serum TG levels were < 1.82 mmol/L and TC levels < 6.2 mmol/L from a population of Chinese Han nationality in Chengdu area. RESULTS: In both HTG group and control group, S1 allele was the major allele and homozygous S1S1 genotype was the most frequent one. The frequency of S2 allele was significantly higher than that reported in Caucasians (0.289 vs 0.06-0.16, P < 0.05). No differences were found in apoC III gene Sst I polymophism in the HTG group when compared with the control group (0.287 vs 0.289, P > 0.05). The genotype of S2S2 was not associated with higher TG and apolipoproteins levels when compared with the genotypes of S1S1 and S1S2 (P > 0.05). CONCLUSION: These results suggest that the Sst I polymorphism of the apoC III gene was not associated with endogenoushypertriglyceridemica in Chinese population.

Adult↗
PubMed2001

[Study on apoE gene polymorphism in Chinese type II b hyperlipidemia].

OBJECTIVE: To study apolipoprotein(apo) E polymorphism and its relationship with plasma lipids and apolipoproteins levels in Chinese patients with type II b hyperlip oproteinemia. METHODS: apoE genotypes were assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method, serum lipids were determined by enzyme method, and apolipoproteins were measured by radial immunodiffusion assay in 74 type II b hyperlipidemia patients whose fasting serum lipids levels were TG > or = 2.26 mmol/L, TC > or = 6.21 mmol/L and in 230 healthy subjects whose fasting serum lipids levels were TG < 1.82 mmol/L, TC < 6.21 mmol/L from a population of Chinese Han nationality in Chengdu area. RESULTS: Compared with the control group, the serum TG, TC, LDLC, nHDLC, apoA II, apoB100, apoC II, apoC III, apoE levels and TG/HDLC ratio in patients with type II b hyperlipidemia were significantly increased(P < 0.001), and the serum HDLC levels and apoE/apoC III ratio were significantly decreased (P < 0.05). ApoE3/3 genotype and allele epsilon 3 frequency in type II b hyperlipidemia group and control group were both the highest. In type II b hyperlipidemia group, allele epsilon 2 frequency tended to increase and allele epsilon 4 frequency tended to decrease as compared with those in the control group (P > 0.05). In type II b hyperlipidemia group the genotype of apoE2 was associated with higher serum TG, apoC II, apoE levels and apoE/apoC III ratio when compared with the genotype of apoE3; the genotype of apoE4 was associated with higher serum TC, nHDLC and apoE levels when compared with the genotypes E3 and E2 (P < 0.001). CONCLUSION: The alleles epsilon 2 and epsilon 4 are associated with serum TG, TC, nHDLC, apoC II and apoE levels to some extent in type II b hyperlipide in Chinese population.

Adult↗
PubMed2001

[The abnormal changes of apolipoprotein(s) in patients with type 2 diabetes mellitus].

OBJECTIVE: To investigate the changes of the apolipoproteins(apoA I, A II, B100, C II, C III, E) in patients with type 2 diabetes mellitus. METHODS: The levels of fasting plasma glucose(FBG), insulin, TG, TC, apoA I, A II, B100, C II, C III, E were all measured in 127 non-diabetic subjects and 143 type 2 diabetic patients (20 associated with coronary heart disease (CHD) and 66 associated with hypertriglyceridemia(HTG), 55 associated with hypercholesterolemia). RESULTS: In male type 2 diabetic patients, the levels of FBG, WHR and apoC II were significantly higher (P < 0.05) and apoA I, A II levels were significantly lower (P < 0.05) than those in male non-diabetic subjects. In female type 2 diabetic patients, the levels of FBG, BMI, WHR, TG significantly elevated while HDL-C, apoA I, A II levels significantly decreased as compared with those in female non-diabetic subjects. In type 2 diabetic group, the levels of WHR, FBG and TG in HTG patients were elevated significantly as compared with those without HTG, and the levels of HDL-C, apoA I and apoA II were decreased; the levels of WHR, TG, TC, apoB100, C II, C III, E in patients with HTC were significantly higher than those whose cholesterol levels were normal. In patients with CHD, the levels of fasting insulin, apoB100, apoC II and apoE were significantly higher than those in patients without CHD, and the levels of HDL-C and apoA II were decreased significantly. CONCLUSION: Abnormal changes of apo(s) in type 2 diabetes mellitus may be a cause of type 2 diabetes associated with HTG and CHD.

Adult↗
PubMed2001

[Effects of retinoic acid on secretion of apolipoproteins A I, A II, B100, C III and E by cultured HepG2 cells].

OBJECTIVE: This study inquired into the role of retinoic acid in lipoprotein metabolism. METHODS: We observed the effect of retinoic acid on the secretion of apolipoproteins A I, A II, C III, B100 and E by cultured HepG2 cells. The apolipoprotiens contents in culture media were measured by radioimmunodiffusion assay (RID) kits developed by our research laboratory. 20-fold lyophilizely condensed culture media were used for the assays. RESULTS: Retinoic acid increased the secretion of apoA I, B100, C III and A II, and it inhibited the secretion of apoE. The effect of retinoic acid was strengthened in a dose-dependent manner. When the concentration of retinoic acid in cultured media was 2 x 10(-4) mol/l, the secretion of apoA I, A II, B100 and C III increased by 14.3% (P < 0.01), 23.8% (P < 0.05), 16.1% (P < 0.01) and 47.6% (P < 0.01) respectively, and the secretion of apoE decreased by 37.2% (P < 0.01). CONCLUSION: These findings indicate that retinoic acid does not have a general effect on apolipoprotein secretion in HepG2 cells.

Apolipoprotein A-I↗
PubMed2001

[The clinical characteristics of adhesive type cholesteatoma].

OBJECTIVE: To study the clinical characteristics of adhesive type cholesteatoma. METHODS: Fifty-two cases (52 ears) of adhesive type cholesteatomas were reviewed. Of the 52 cases there were 30 males and 22 females; 24 left ears and 28 right ears. The age of the patients ranged from 8 to 70 years. All of the patients were treated by tympanoplasty, and the open and close methods were performed in 37 ears and 10 ears, respectively. Other methods were employed in the remaining 5 cases. Nine ears underwent tympanoplasty type "O" without ossicular re-construction for an increase in the threshold of the bone conduction. Types I, III and IV tympanoplasties were performed in 1, 16 and 26 ears, respectively. RESULTS: The structures of the upper parts of the stapes had disappeared in 25 ears, which was significantly higher in this series than that in the attic type cholesteatoma. The over-all recovery rate of hearing was 69.8%, while 75.9% and 55.6% in the open and closed tympanoplasties, respectively. Postoperative complications of perforations and re-adhesions of the tense part of the tympanic membrane were observed in 3 and 4 ears, respectively. CONCLUSIONS: Adhesive type cholesteatoma is not uncommon. The cause of this disease may be the functional defects in the pharynotympanic tube. A thorough and effective treatment for the secretory otitis media is crucial for the prevention of adhesive type cholesteatomas. The open method tympanoplasty was considered as the first choice for adhesive type cholesteatoma while the closed method must be great careful.

Adolescent↗
PubMed2001

[Spontaneous otoacoustic emissions and efferent control of cochlea].

OBJECTIVE: To study the relationship between spontaneous otoacoustic emissions(SOAE) and efferent control of cochlea and their clinical significance. METHODS: SOAE, transient evoked otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE) and contralateral white noise (60 dB SPL) suppression of TEOAE and DPOAE experiments were conducted in 312 ears of 95 patients with retrocochlear impairment and/or MOCS dysfunction and 64 normal young adults. RESULTS: MOCS dysfunction was shown in 126 ears of 65 patients (130 ears) with auditory neuropathy, 2 ears of 2 patients with unilateral acoustic neuroma, 4 ears of 2 patients with hyperacusis, 14 ears of 26 patients(48 ears) with normal hearing level in unilateral or bilateral tinnitus. Stronger EOAE could be recorded in total 146 ears with MOCS dysfunction at any pure tone hearing level. SOAE could be recorded in 126 of 146 ears (86.3%) with MOCS dysfunction and 44 of 128 ears (34.3%) with normal hearing. SOAE of ears with MOCS dysfunction was mainly at frequencies from 0.693 to 3.055 kHz and SOAE of normal ears was at frequencies from 1.135 to 2.746 kHz. Average value of maximum amplitude of SOAE spectrum (-3.4 +/- 6.4) dB SPL was significantly greater than that in normal ears (-6.8 +/- 7.8) dB SPL (P < 0.01). The major frequency range of SOAE (0.693-3.055 kHz) in MOCS dysfunction ears was essentially consistent with that of efferent suppression in normal ears (0.7-3 kHz). CONCLUSION: The modulation of the cochlear active mechanisms by MOCS mainly presents in the low- and mid-frequency regions, these frequencies correspond to the frequency range of SOAE. Stronger SOAE indicates pathophysiological significance. There is a clear clinical relationship between SOAE and the efferent modulation of the cochlea.

Adolescent↗
PubMed2001

[Study on the energy transfer fluorescence quenching among combination of acridine yellow-PAR determination of trace iron].

An energy transfers technique between 4-(2-Pyridylazo) resorcinol(PAR) and acridine yellow is studied, and optimum experimental conditions of energy transfer is done as well. It is found that in the aqueous solution of sodium lauryl sulfate, NH3.H2O-NH4Cl buffer solution at pH = 9.2, the energy transfers from acridine yellow to iron(II)-PAR complexes. So a new method of fluorometric energy transfers determination of trace iron(II) by acridine yellow--PAR was described. The range of determination of iron is 0-10 micrograms.L-1. The detection limit for iron is 0.06 microgram.L-1. The method has been applied to the determination of iron in water sample and hair with satisfactory results.

Aminoacridines↗
PubMed2000

Applying phage antibodies to proteomics: selecting single chain Fv antibodies to antigens blotted on nitrocellulose.

Two-dimensional gel electrophoresis is a powerful tool for identification of proteins that differ between patients with qualitatively or quantitatively different disease states. Further characterization of these protein differences would be greatly facilitated by the availability of antibodies that could be used to detect and quantitate the temporo-spatial pattern and cellular and tissue location of the different proteins. To generate such antibodies, methods were developed which permit the successful selection of monoclonal phage antibodies from phage display libraries against antigens blotted from SDS-PAGE gels onto nitrocellulose. First, it was determined that nitrocellulose and PVDF membranes gave significantly lower levels of background phage binding than two other membranes studied. Next, it was determined that blocking with fish gelatin and binding in the presence of 0.5 M NaCl could reduce nonspecific binding 10,000-fold and result in enrichment ratios greater than 500-fold with antigen concentrations as low as 1 ng/mm(2). When optimized conditions were applied to phage antibody libraries, panels of monoclonal phage antibodies were generated against the proteins ErbB2 and bovine serum albumin electroblotted from SDS-PAGE gels onto nitrocellulose. Antibodies were obtained with as little as 10 to 1 ng of antigen, depending on whether the libraries displayed single or multiple copies of antibody per phage. The antibodies worked as reagents in both ELISA and Western blotting.

Animals↗
PubMed2000

Ambient sulfate concentration and chronic disease mortality in Beijing.

In this study, ecological analysis was used to assess the relationship between ambient air pollution and human mortality. All the data on environmental measures and related factors, population size and number of deaths were collected for the city of Beijing, PR China and its eight districts for the years 1980-1992. In this study the concentration of SO(4)2- was selected as a main indicator of environmental pollution for the following reasons: (i) SO(4)2- data are available to cover all urban and suburban areas in Beijing compared with other air pollutants during the study period; (ii) SO(4)2- levels indicate the concentration of sulfide (include sulfate) and acid fog in the air, and they are significantly lower in cleaner districts than in others; and (iii) analyses showed that SO(4)2- levels are significantly correlated with daily mean concentrations of sulfur dioxide and nitrogen oxide, annual coal combustion, number of households using gas fuel, counts of motor vehicles and population density. Age-standardised mortality rates due to specific diseases were calculated using the Chinese population census data in 1990. Statistically significant correlations were observed between SO(4)2- concentration and total mortality and mortality due to cardiovascular disease, malignant tumour and lung cancer (r > 0.50 in all cases). The correlations were not only found between the current SO(4)2- concentration and these mortalities, but also for SO(4)2- levels measured up to 12 years prior to death, which may suggest long-term effects of air pollution. No significant correlations were observed for mortality from respiratory diseases and cerebrovascular diseases (r = 0.30-0.50). This study indicates that the concentration of SO(4)2- in air is a useful air pollution indicator in the areas where coal is used as the main source of energy. Areas with high levels of SO(4)2- experienced higher mortality due to a variety of chronic diseases.

Air Pollutants↗
PubMed2000

Direct functional interactions between insulin-like growth factor-binding protein-3 and retinoid X receptor-alpha regulate transcriptional signaling and apoptosis.

Insulin-like growth factor-binding protein (IGFBP)-3 regulates apoptosis in an IGF-independent fashion and has been shown to localize to nuclei. We cloned the nuclear receptor retinoid X receptor-alpha(RXR-alpha) as an IGFBP-3 protein partner in a yeast two-hybrid screen. Multiple methodologies showed that IGFBP-3 and RXR-alpha bind each other within the nucleus. IGFBP-3-induced apoptosis was abolished in RXR-alpha-knockout cells. IGFBP-3 and RXR ligands were additive in inducing apoptosis in prostate cancer cells. IGFBP-3 enhanced RXR response element and inhibited RARE signaling. Thus, RXR-alpha-IGFBP-3 interaction leads to modulation of the transcriptional activity of RXR-alpha and is essential for mediating the effects of IGFBP-3 on apoptosis.

Amino Acid Sequence↗
PubMed2000

Rhodium(II)-catalyzed cyclization of amido diazo carbonyl compounds.

A series of acyclic diazo ketoamides were prepared from N-benzoyl-N-alkylaminopropanoic acids and were treated with a catalytic amount of rhodium(II) acetate. The resultant carbenoids underwent facile cyclization onto the neighboring amide carbonyl oxygen atom to generate seven-membered carbonyl ylide dipoles. Subsequent collapse of the dipoles with charge dissipation produce bicyclic epoxides which undergo further reorganization to give substituted 5-hydroxydihydropyridones in good yield. Depending on the nature of the substituent groups, it was possible to trap some of the initially formed carbonyl ylide dipoles with a reactive dipolarophile such as DMAD. In other cases, cyclization of the dipole to the epoxide is much faster than bimolecular trapping. A related cyclization/rearrangement sequence occurred when diazo ketoamides derived from the cyclic pyrrolidone and piperidone ring systems were subjected to catalytic quantities of Rh(II) acetate. With these systems, exclusive O-cyclization of the amido group onto the carbenoid center occurs to generate a seven-ring carbonyl ylide dipole. Starting materials are easily prepared, and the cascade sequence proceeds in good yield and does not require special precautions. The overall procedure represents an efficient one-pot approach toward the synthesis of various indolizidine and quinolizidine ring systems.

Catalysis↗
PubMed2000

Probing trace phenols based on mediator-free alumina sol--gel-derived tyrosinase biosensor.

A novel tyrosinase biosensor has been developed for the subnanomolar detection of phenols, based on the immobilization of tyrosinase in a positively charged Al2O3 sol-gel membrane on a glassy carbon electrode. It has been found that Al2O3 sol-gel is perfectly beneficial to the immobilization of tyrosinase, because it not only possesses the general advantages of sol-gel but it also is an effective promoter of the biosensor. The large microscopic surface area, porous morphology, and hydrophilic property of the sol-gel matrix result in high enzyme loading, and the enzyme entrapped in this matrix retains its activity to a large extent. The Al2O3 sol-gel-containing surface also displays an intrinsic electrocatalytic o-quinone response and, hence, offers a high-sensitivity (127 microA mM(-1)) monitoring of phenols. The detection limit is 0.2 nM at a signal-to-noise ratio of 3, the response time is less than 4 s reaching 95% of the steady-state value, and 70% of the activity is retained after 3 months.

Biosensing Techniques↗
PubMed2000

Immune modulatory effects of neural cell adhesion molecules on lipopolysaccharide-induced nitric oxide production by cultured glia.

Activation of glial cells often occurs at sites of neuronal injury or death and where there is disruption of communication between glia and neurons. We have previously reported that neurons exert an inhibitory influence on LPS-stimulated nitric oxide (NO) production in glial cells. We hypothesized that neural cell adhesion molecules (NCAM) might mediate this inhibitory effect, and this study was designed to elucidate the role of NCAM on lipopolysaccharide (LPS)-induced NO production. We found that soluble NCAMs reduced LPS-stimulated NO production by cultured glia. A monoclonal antibody that recognizes the third immunoglobulin (Ig) domain and can mimic the functions of NCAMs reduced LPS-stimulated NO production, whereas another antibody that binds to other regions of the NCAM did not modulate NO production. Using a 10-amino acid peptide from the third Ig domain of the NCAM, a peptide fragment within the region recognized by the NCAM antibody, mimics the effect of the molecule in reducing NO production. This study demonstrated that NCAMs could modulate LPS-stimulated NO production, most likely via interaction between NCAMs. These results suggest that neuron-glia interactions via NCAMs play an important role in regulating the activities of glial cells in the brain.

Adjuvants, Immunologic↗
PubMed2000

Scanning electrochemical microscopy of living cells: different redox activities of nonmetastatic and metastatic human breast cells.

Electrochemical methods have been widely used to monitor physiologically important molecules in biological systems. This report describes the first application of the scanning electrochemical microscope (SECM) to probe the redox activity of individual living cells. The possibilities of measuring the rate and investigating the pathway of transmembrane charge transfer are demonstrated. By this approach, significant differences are detected in the redox responses given by nonmotile, nontransformed human breast epithelial cells, breast cells with a high level of motility (engendered by overexpression of protein kinase Calpha), and highly metastatic breast cancer cells. SECM analysis of the three cell lines reveals reproducible differences with respect to the kinetics of charge transfer by several redox mediators.

Animals↗