Biomedical subjects

Qing Liu

Publications and source records attributed to Qing Liu.

At least 55 records · Page 3Linked to original sources

PubMed2006

[Determination of six metal elements in plant Bupleurum scorzoneri folium Willd. by flame atomic absorption spectrophotometry (FAAS)].

The objective in this paper was to determine the amount of metal elements in the Plant Bupleurum scorzoneri folium Willd. by flame atomic absorption spectrophotometry (FAAS). FAAS method was established for the determination of Ca, Mg, Fe, Cu, Zn and Pb in the Plant Bupleurum scorzoneri folium Willd. after digestion with HNO3-HClO4 (V : V= 4 : 1) at 90-95 degrees C and at normal pressure. In the meantime, the optimum parameters of FAAS and the effects of solution medium on the results were studied. The analytical results of Ca, Mg, Fe, Cu and Zn were 5,588.9, 1,790.5, 869.3, 78.4, 44.3 microg x g(-1) respectively, and Pb was not checked out in the samples. The results showed that the recovery of standard addition was 99.57%-102.10%, the relative standard deviation (n= 9) was 0.18%-2.26%. The method is quick, simple and convenient, and the results are satisfactory.

Bupleurum↗

PubMed2006

[Determination of thirteen metal elements in the plant Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry].

The objective of the paper is to determine the amount of metal elements of Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Co, Ni, Cd, Cr and Pb in the planted Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry (FAAS), after the cinefaction and the digestion with HNO3-HClO4 (phi 4:1) at 90-95 degrees C and normal pressure. The optimum parameters of FAAS and the effects of solution medium on the results were investigated. The analytical results show that the amount of Na, K, Mg, Ca, Mn, Fe, Cu, Zn and Pb was 1508.7, 27653.0, 2036.0, 4848.1, 24.8, 323.5, 15.2, 23.7 and 10.8 microg x g(-1), respectively, and that of Co, Ni, Cd and Cr was not checked out in the samples. The recovery of standard addition is 97.45%-102.50%, the relative standard deviation (n=9) was 0.34%-2.77%. The characteristic method is quick, simple and convenient and the results are satisfactory.

Foeniculum↗

PubMed2005

Solvent effects on infrared spectroscopy of 17beta-hydroxy-17-methyl-2-oxa-5alpha-androstan-3-one in single solvents.

Infrared spectroscopy studies of 17beta-hydroxy-17-methyl-2-oxa-5alpha-androstan-3-one (HMOA) in 20 different pure organic solvents were undertaken to investigate the solute-solvent interactions and to correlate solvent properties, such as the KBM equation, the solvent acceptor number (AN), Schleyer's linear free energy equation (G-value), Dimroth and Reichardt's parameter E(T)(30) and Brownstein's parameter S with the frequency shifts of the carbonyl stretching vibration for solute. The result indicated that the KBM relationship is unsuitable to the complicated molecules. These frequencies exhibited a better correlation with the solvent parameters AN and G-value than others.

Dihydrotestosterone↗

PubMed2005

Characteristic neuronal firing interspike intervals in laterodorsal thalamic nuclei induced by tetanization of rat caudate putamen: possible relations to hippocampal electroencephalogram changes.

The purpose of the present work was to study the effect of acute tetanization of the right caudate putamen nucleus (ATRC) on single neuronal interspike intervals (ISIs) in both laterodorsal thalamic nuclei (LDi), and electroencephalogram (EEG) wave interpeak intervals (IPIs) in both hippocampi (HPCi). Experiments were performed on 21 male Sprague-Dawley rats weighing 150~250 g. The seizures were induced by the ATRC (60 Hz, 2 s, 0.4~0.6 mA). Quadruple recordings were simultaneously carried out: two for single unit recordings from both LDi, and two for EEG recordings from both HPCi. The ATRC induced: (1) An interactive epileptic electrical network reconstructed in bilateral HPCi, which was driven by primary afterdischarges of single LD neuron. (2) A symmetric mirror-like ISI spot distribution of the LD neuronal firing before and after tetanus. (3) Gradually prolonged LD neuronal discharge intermittence was coherent with synchronous hippocampal EEG activities on the contralateral side. (4) Single LD neuronal spikes were phase- and time-locked to 20~25 Hz gamma oscillations in contralateral HPC. It suggests a particular temporal code patterning of single LD neuronal firing and its relationships to hippocampal EEG wave code in time series, the latter implies the LD neuronal encoding mechanisms of ATRC-induced epileptic electrical network in bilateral HPCi.

Action Potentials↗

PubMed2005

Analysis of spliceosomal complexes in Trypanosoma brucei and silencing of two splicing factors Prp31 and Prp43.

In trypanosomatids all mRNAs undergo trans-splicing, whereas cis-splicing is restricted to a few transcripts. Trans-splicing is mechanistically similar to cis-splicing, however, little is known about the trans-splicing machinery and its underlying mechanism. In this study, we examined the involvement of splicing factors in cis- and trans-splicing by RNA interference (RNAi). Two factors (Prp31 and Prp43) were found to be essential for both pathways, suggesting that splicing factors are shared by these two reactions. We identified a 45S complex carrying pre-mRNA and all the U-snRNAs, including U1 and the SL RNA, suggesting that a single spliceosomal complex may potentially conduct both trans- and cis-splicing.

Animals↗

PubMed2005

Surface complexation of condensed phosphate to aluminum hydroxide: an ATR-FTIR spectroscopic investigation.

Two model compounds, sodium pyrophosphate (pyro-P) and sodium tripolyphosphate (tripoly-P), were employed to elucidate the binding mechanisms of condensed phosphate on aluminum hydroxide by utilizing attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Peak assignments for the condensed phosphates in the solution phase and those adsorbed on the surface of aluminum hydroxide were made. Electron delocalization and polarization were employed to explain the peak shifts and the complexation of condensed phosphate with aluminum hydroxide. The tripoly-P and pyro-P were adsorbed on aluminum hydroxide by forming inner-sphere complexes. The adsorbed condensed phosphates were deprotonated in the pH range from 4 to 10. Monodentate, bidentate, and binuclear complexes were formed when pyro-P was adsorbed on aluminum hydroxide, while monodentate and binuclear complexes were formed when tripoly-P was adsorbed. Based on the FTIR data, we proposed that when either bidentate or binuclear complexes were formed, the two oxygen atoms participating in the complexation with aluminum hydroxide could not be originated from the same terminal phosphate moiety. The AlO bond formed in the complexation of pyro-P or tripoly-P with aluminum hydroxide (AlPO(-3)) was not as strong as the HO bond in terminal HPO(-3). The bridging PO(-2) of tripoly-P did not coordinate with aluminum hydroxide. The real-time ATR-FTIR study on condensed phosphate adsorption revealed that a long contact time between condensed phosphates and aluminum hydroxide particles can result in a transformation of an initially formed species into a thermodynamically more stable phase.

Adsorption↗

PubMed2005

Complex regulation of spiral ganglion neuron firing patterns by neurotrophin-3.

Auditory information is conveyed into the CNS via the spiral ganglion neurons, cells that possess distinctive electrophysiological properties that vary according to their cochlear innervation. Neurons from the base of the cochlea fire action potentials with shorter latencies and durations with more rapid accommodation than apical neurons (Adamson et al., 2002b). Interestingly, these features are altered by exposure to brain-derived neurotrophic factor and neurotrophin-3 (NT-3), suggesting that the electrophysiological diversity is not preprogrammed into the neurons but instead results from extrinsic regulation. In support of this, gradients of neurotrophins exist in the cochlea that could account for the apex- base differences in firing. To understand the determinants of spiral ganglion function, we characterized the NT-3 concentration dependence and mode of action on spiral ganglion neurons. Whole-cell current-clamp recordings were made from mouse basal spiral ganglion neurons (postnatal day 5) exposed to different concentrations of NT-3 for 3 d in vitro. Measurements of accommodation, latency, onset time course, and action potential latency revealed a nonmonotonic dependence on NT-3 concentration, with a peak effect occurring at 10 ng/ml. Addition of NT-3 at different time points showed that neurotrophin exposure altered the firing features of existing neurons rather than supporting differential survival. These experiments establish that the electrophysiological phenotype of spiral ganglion neurons depends critically on the precise concentration of NT-3 and that the functional organization of this component of the peripheral auditory system results from a complex interplay between multiple kinds of neurotrophins and their cognate receptors.

Action Potentials↗

PubMed2005

Prevalence of porcine endogenous retrovirus in Chinese pig breeds and in patients treated with a porcine liver cell-based bioreactor.

AIM: To determine the prevalence of porcine endogenous retrovirus (PERV) in various pig breeds raised in China including Chinese experimental mini-pigs by PERV-reverse transcriptase (PERV-RT enzyme). Moreover, the potential for infection of PERV was investigated in patients treated with a bioreactor based on porcine liver cells (n = 3). METHODS: Pig serum, liver and muscle cell-free supernatants were collected from various Chinese pig breeds. Porcine hepatocytes were isolated with a two-step perfusion method. Three patients with acute or chronic liver failure were treated with a bioartificial liver support system (BALSS) for 8-12 h and serum samples were collected from the patients before, immediately after and 30 d after treatment. RESULTS: The activities of PERV-RT enzyme in pig liver and muscle cell-free supernatants were higher than in normal human controls. PERV-TR enzyme activity did not increase in patients before and after 1 mo of treatment. PERV-RT activities were not significantly different when compared with pre-treatment group (1.544+/-0.155576), the post-treatment groups (1.501+/-0.053507, 1.461+/-0.033808 and 1.6006667+/-0.01963 for 0, 14 and 30 d post-treatment, respectively, P>0.05), and normal control group (1.440+/- 1.0641, P>0.05). RT enzyme activity in Chinese experimental mini-pigs was higher than in normal human control group (1.440+/-1.0641 U/mL, P<0.05), and not significantly different (P>0.05) when compared with the pig breeds except in the muscle supernatants. All the samples including muscle and liver cell supernatants from the Chinese mini-experimental pigs and the four domestic Chinese pig breeds contained PERVs. CONCLUSION: These results suggest that the risk of PERV infection through BALSS containing porcine liver cells without immunosuppressants may be quite low. Although there were PERVs in Chinese experimental mini-pigs and porcine liver cell culture suspensions, we did not find any evidence of persistent PERV infection in patients treated with this porcine hepatocyte-based bioartificial liver.

Adult↗

PubMed2005

CAPRI and RASAL impose different modes of information processing on Ras due to contrasting temporal filtering of Ca2+.

The versatility of Ca2+ as a second messenger lies in the complex manner in which Ca2+ signals are generated. How information contained within the Ca2+ code is interpreted underlies cell function. Recently, we identified CAPRI and RASAL as related Ca2+-triggered Ras GTPase-activating proteins. RASAL tracks agonist-stimulated Ca2+ oscillations by repetitively associating with the plasma membrane, yet CAPRI displays a long-lasting Ca2+-triggered translocation that is refractory to cytosolic Ca2+ oscillations. CAPRI behavior is Ca2+- and C2 domain-dependent but sustained recruitment is predominantly Ca2+ independent, necessitating integration of Ca2+ by the C2 domains with agonist-evoked plasma membrane interaction sites for the pleckstrin homology domain. Using an assay to monitor Ras activity in real time, we correlate the spatial and temporal translocation of CAPRI with the deactivation of H-Ras. CAPRI seems to low-pass filter the Ca2+ signal, converting different intensities of stimulation into different durations of Ras activity in contrast to the preservation of Ca2+ frequency information by RASAL, suggesting sophisticated modes of Ca2+-regulated Ras deactivation.

Animals↗

PubMed2005

[Application of Model for end-stage liver disease to predict the prognosis of and curative effect for chronic severe hepatitis].

OBJECTIVE: To compare the capability in predicting the prognosis of chronic severe hepatitis among 3 prediction systems: Model for end-stage liver disease (MELD), Child-Turcotte-Pugh (CTP) system, and King's College Hospital (KCP) system, and to explore the capability of MELD in predicting the curative effect of artificial liver. METHODS: Scoring was made among 66 patients of chronic severe liver diseases with the underlying disease of hepatitis B, 11 in early stage, 14 in middle stage, 15 in late stage, and 26 unclassified, by MELD, CTP, and KCP systems. The accuracy of each system was evaluated by ROC curve, the differences between the systems was analyzed by Kaplan-Meier survival curve. RESULTS: The MELD score of the patients at admission predicted the mortality within 3 months with the c-statistic of 0.894, higher than those of the CTP and KCP systems (0.703 and 0.89 respectively). The MELD scores of the patients in the early stage was 24 +/- 4, significantly lower than those in the middle and late stages (31.11 +/- 2.90 and 41.38 +/- 9.98 respectively, all P < 0.01). The MELD score was positively correlated with the stage of disease (r = 0.737, P < 0.01). The mortally was 10.7% for the patients with an admission MELD score < or = 30, was 47% for the patients with an admission MELD score of 31 approximately 39, and was 60% the patients with an admission MELD score of > or = 40. CONCLUSION: The predictive capability of MELD system is better than the KCP and CTP systems. Artificial liver support treatment is the best choice e for the patients with an admission MELD score of 31-39. An admission MELD score > 40 is the indication for liver transplantation.

Hepatitis, Chronic↗

PubMed2005

Phase-only encryption and watermarking based on phase-shifting interferometry.

Generally, the reconstruction of an object image from its diffraction field requires both the amplitude and the phase information of this field. We systematically investigated the effects of using only the real part, the imaginary part, or the phase information of the diffraction field to reconstruct the original image for both the binary and the gray-level images. We show that the phase information can yield a better result of image retrieval than the real or imaginary part and that the recovered image from the phase information is satisfactory especially for binary input. On the basis of this idea, a new technique of image encryption and watermarking by use of only one delivered image-the phase map of the diffraction field of the original image-through double random-phase encoding is proposed and verified by computer simulations with phase-shifting interferometry. This method can greatly cut down the communication load and is suitable for Internet transmission.

Journal Article↗

PubMed2005

[Acetabular retroversion in hip dysplasia].

OBJECTIVE: To study the occurrence and radiograph features of the acetabular retroversion in hip dysplasia, and to evaluate the effects on the retroversion by the traditional maneuvers in the periacetabular osteotomy. METHODS: Bernese periacetabular osteotomy was performed to 45 continuous dysplastic hips (43 patients) from December 2001 to November 2003. There were 37 female (39 hips) and 6 male (6 hips), average age was 28.9 (range, 15-45). The diagnosis of acetabular retroversion was based on the "cross-over" and "posterior wall" signs on the standard radiographs of the patients pre- or postoperatively. RESULTS: Among total 45 hips, the "cross-over" sign was positive in 8 hips, whereas including the "posterior wall" sign positive in 5 hips. The occurrence of retroversion was 17.8%. And the cross-over points were located within the superior 1/3 of the acetabulums in all cases. After the osteotomy, all the cross-over points moved to the inferior 1/3 of the acetabulums, and the "posterior wall" sign was seen in all 8 cases. CONCLUSIONS: Approximately one sixth of the patients with acetabular dysplasia have retroversion in which the superior 1/3 of the acetabulum faces posterolaterally. The retroversion can be identified with the standard AP pelvic radiographs. With the traditional maneuvers in periacetabular osteotomy, the retroversion will be aggravated in these patients.

Acetabulum↗

PubMed2005

Lys6-modified ubiquitin inhibits ubiquitin-dependent protein degradation.

Ubiquitin plays essential roles in various cellular processes; therefore, it is of keen interest to study the structure-function relationship of ubiquitin itself. We investigated the modification of Lys(6) of ubiquitin and its physiological consequences. Mass spectrometry-based peptide mapping and N-terminal sequencing demonstrated that, of the 7 Lys residues in ubiquitin, Lys(6) was the most readily labeled with sulfosuccinimidobiotin. Lys(6)-biotinylated ubiquitin was incorporated into high molecular mass ubiquitin conjugates as efficiently as unmodified ubiquitin. However, Lys(6)-biotinylated ubiquitin inhibited ubiquitin-dependent proteolysis, as conjugates formed with Lys(6)-biotinylated ubiquitin were resistant to proteasomal degradation. Ubiquitins with a mutation of Lys(6) had similar phenotypes as Lys(6)-biotinylated ubiquitin. Lys(6) mutant ubiquitins (K6A, K6R, and K6W) also inhibited ATP-dependent proteolysis and caused accumulation of ubiquitin conjugates. Conjugates formed with K6W mutant ubiquitin were also resistant to proteasomal degradation. The dominant-negative effect of Lys(6)-modified ubiquitin was further demonstrated in intact cells. Overexpression of K6W mutant ubiquitin resulted in accumulation of intracellular ubiquitin conjugates, stabilization of typical substrates for ubiquitin-dependent proteolysis, and enhanced susceptibility to oxidative stress. Taken together, these results show that Lys(6)-modified ubiquitin is a potent and specific inhibitor of ubiquitin-mediated protein degradation.

Adenosine Triphosphate↗

PubMed2005

[Clinical study of CT virtual endoscopy in staging diagnosis of bladder tumors].

OBJECTIVE: To evaluate CT virtual endoscopy (CTVE) based on spiral CT in the staging diagnosis of bladder neoplasms and its clinical application. METHODS: Forty patients with bladder neoplasms and 10 normal patients underwent volume scanning using spiral CT. All images with thin collimation and overlapping reconstruction were transferred to computer workstation to obtain the images of CTVE. The results of all CTVE findings were compared with those of conventional CT, cystoscopy, operation and pathological data. RESULTS: CTVE showed the normal anatomical structure of bladder as actual cystoscopy. The size, configuration, location and extension of bladder neoplasms was detected by CTVE scans agreed with that of actual cystoscopy. CTVE revealed the structure of trigone of urinary bladder that were not available in actual cystoscopy, and they were confirmed operatively and compared with the pathological results according to the TNM classification of malignant neoplasms. The sensitivity of CTVE for bladder tumors and accuracy in preoperative neoplasms staging was 98% (39/40) and 85% (33/39), respectively. The sensitivity of mass detection of diameter > or = 0.5 cm was 100%. The results were studied in a blind way. CONCLUSIONS: CTVE is a noninvasive, safe and reliable procedure in the staging diagnosis of bladder neoplasms. CTVE can well show bladder neck anatomy and serve as an important complementary method to conventional cystoscopy. The limitation of CTVE is that it can not observe change of mucosal appearances and perform biopsy.

Adolescent↗

PubMed2005

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Journal Article↗

PubMed2005

Metabolic engineering of new fatty acids in plants.

Metabolic engineering of plants to express high levels of new fatty acids that are of nutritional and industrial importance has proven to be highly challenging. Significant advances have been made recently, however, particularly in the development of the first plant oils to contain long-chain polyunsaturated fatty acids, such as arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Methods of increasing the accumulation of Delta12-modified fatty acids synthesized by transgenically expressed FAD2-like enzymes have also been investigated. Biochemical analyses of plants that express these introduced fatty-acid metabolic pathways have highlighted the central importance of ensuring the removal of novel fatty acids from their site of synthesis on phosphatidylcholine to enable their further modification, exclusion from membrane lipids and accumulation in seed triacylglycerols.

Fatty Acids, Nonesterified↗

PubMed2005

Antioxidants and trichostatin A synergistically protect against in vitro cytotoxicity of Ni2+ in human hepatoma cells.

The objective of this study was to investigate the separate and combined effects of antioxidants, trichostatin A (TSA) and their combination on the in vitro cytotoxicity of Ni2+ in human hepatoma cells. Cell viability, lactate dehydrogenase (LDH) release, and DNA fragmentation were measured as indicators of cell damage. Reactive oxygen species (ROS) generation and histone acetylation were also measured. The cytotoxicity of Ni2+ increased in a time- and dose-dependent manner. In the presence of 2 mM Ni2+, ROS generation increased 365% (p<0.05), while histone acetylation decreased 37% (p<0.05). Although antioxidants, ascorbic acid (AA, 0.5 or 1 mM), reduced glutathione (GSH, 100 or 200 microM) and N-acetyl-cysteine (NAC, 0.5 or 1 mM) strongly inhibited ROS generation, their effect on Ni2+-caused histone hypoacetylation was not so obvious. On the contrary, TSA (100 nM) showed no inhibition on ROS generation but significantly increased histone acetylation in both control and Ni2+-exposed cells. As expected, the combination of antioxidants and TSA possessed the activity of both diminishing ROS generation and increasing histone hypoacetylation caused by Ni2+. Further studies found that both antioxidants and TSA could diminish the cytotoxicity of Ni2+, and their combined effects obviously improved each of their protection roles, indicating that both ROS generation and histone hypoacetylation are involved in the cytotoxicity of Ni2+, and the combination of antioxidants and TSA may act as a useful strategy to protect against this cytotoxicity.

Acetylation↗

PubMed2005

Adaptive regression.

Adjustment for prognostic covariates is recommended in clinical trials because relative to a t-test, it improves precision and adjusts for treatment imbalances caused by an "unlucky" randomization. But, inclusion of too many covariates can be counterproductive. In the quest to strike a balance between inclusion of all important variables and not going overboard, people have proposed methods such as stepwise regression, whereby the decision to include a covariate depends on post-randomization data. Covariate inclusion decisions are typically based on either the strength of its correlation with the outcome or the degree of treatment imbalance. Are these methods valid? Is there a valid way to analyze such data? These are some of the questions we address.

Algorithms↗