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Biomedical subjects

Min Liu

Publications and source records attributed to Min Liu.

At least 163 records · Page 9Linked to original sources
PubMed2003

Expression of biologically active rat apolipoprotein AIV in Escherichia coli.

Rat apolipoprotein AIV (apo AIV) is a 43-kDa intestinal apolipoprotein that is important in lipid metabolism and the suppression of food intake. In this study, a full-length rat apo AIV was expressed in Escherichia coli and purified in a bioactive form. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric analysis revealed that the isolated recombinant protein has a molecular mass of approximately 43 kDa, similar to that of natural rat apo AIV. Immunoblot analysis and N-terminal amino acid sequencing confirmed the identity of the recombinant apo AIV protein as natural rat apo AIV. The recombinant protein was functional in lipoprotein binding assays. Biological activity was assessed behaviorally in that the recombinant protein suppressed food intake of fasted rats comparably to natural rat apo AIV. Neither native nor recombinant apo AIV elicited a conditioned taste aversion (CTA) at doses that suppress feeding. These results indicate that the recombinant apo AIV is structurally and functionally indistinguishable from rat natural apo AIV, making this overexpression and purification scheme a powerful tool for future structure and function studies.

Amino Acid Sequence↗
PubMed2003

Regulation of intestinal and hypothalamic apolipoprotein A-IV.

This review discusses the regulation of the intestinal and hypothalamic apolipoprotein A-IV (apo A-IV) gene and protein expression. Apo A-IV is a glycoprotein secreted together with triglyceride-rich lipoproteins by the small intestine. Intestinal apo A-IV synthesis is stimulated by fat absorption, probably mediated by chylomicron formation. This stimulation of intestinal apo A-IV synthesis is attenuated by intravenous leptin infusion. Chronic ingestion of a high-fat diet blunts the intestinal apo A-IV in response to dietary lipid. Intestinal apo A-IV synthesis is also stimulated by members of the pancreatic polypeptide family, including peptide YY (PYY), neuropeptide Y (NPY), and pancreatic polypeptide (PP). Recently, apo A-IV was demonstrated to be present in the hypothalamus as well. Hypothalamic apo A-IV level was reduced by food deprivation and restored by lipid feeding. Intracerebroventricular administration of apo A-IV antiserum stimulated feeding and decreased the hypothalamic apo A-IV mRNA level, implying that feeding is intimately regulated by endogenous hypothalamic apo A-IV. Central administration of NPY significantly increased hypothalamic apo A-IV mRNA levels in a dose-dependent manner.

Animals↗
PubMed2003

Invasive pneumococcal disease among children in Victoria.

This study analysed notification data from the first year of enhanced surveillance of invasive pneumococcal disease (IPD) in Victoria (1 July 2001 - 30 June 2002), with a focus on risk factors for infection and vaccination status among children under five years of age. Overall, there were 397 notifications (8.2 per 100,000 population), 131 (33%) were children under five years of age. The highest notification rates were among those aged less than two years (72.6 per 100,000 population). Among children aged less than five years: bacteraemia without a primary focus of infection was the most common clinical presentation (64%); 89 per cent were hospitalised with the median length of stay being three days; four children (3%) died. There were 107 cases of a known serotype, 92% (n = 98) were either in or closely related to those included in the 7-valent conjugate pneumococcal vaccine (7vPCV). Most cases (98%) were not eligible for free 7vPCV under the currently funded program in Victoria. Only one child had been vaccinated. The results from the first year of enhanced IPD surveillance in Victoria suggest consideration should be given to extending the publicly funded program to include all children under two years of age.

Age Distribution↗
PubMed2003

[GDNF expression following the severe brain injury in rats].

OBJECTIVE: To evaluate the changes of GDNF after severe brain injury. METHODS: Changes GDNF in cortex, thalamus and pontine was observed by using immunohistochemistry and image analysis technique. RESULTS: The lever of GDNF was increasing at 1 d, reaching peak at 3 d, not obviously decreasing at 5 d and still higher than normal at 7 d after severe brain injury. CONCLUSION: As an objective indication, the time sequence regularity of GDNF after brain injury may be applied in brain injury time estimation.

Animals↗
PubMed2003

[A study on the expression of VEGF in the blunt injury of rat's skin].

OBJECTIVE: To evaluate changes of VEGF in skin after blunt injury. METHODS: The rats of injury groups were subjected to skin blunt injury by free-falling iron hammer. The samples taken at 1 h, 3 h, 6 h, 12 h, 1 d, 3 d, 5 d, 7 d, 9 d after injury were studied by immunohistochemistry and MIAS image analysis system. RESULTS: In the skin of normal control group the expression level of VEGF was low. The increase of VEGF could be observed at 1 day after injury, reached peak at 7 days and declined at 9 days. CONCLUSION: Blunt injury in the skin could induce the expression of the VEGF. Moreover, the change pattern of VEGF level was quite regular with time and could be used to estimate the time after skin injury.

Animals↗
PubMed2003

[Values of soluble thrombomodulin and von Willebrand factor judging reject reaction in liver transplantation].

OBJECTIVE: To find sensitive and specific laboratory examination items for early diagnosing and monitoring liver transplantation reject reaction. METHODS: Randomly investigate 41 liver transplantation patients, among them there were 16 patients with reject reaction (including 12 with acute rejection, 4 with chronic rejection). Plasma soluble thrombomodulin (STM) and von Willebrand factor (vWF) levels were measured before operation and every other day after operation. RESULTS: Plasma STM level increased significantly after operation, two days before rejection and after acute rejection (5.58 ng/ml +/- 0.42 ng/ml, 5.93 ng/ml +/- 0.45 ng/ml, and 7.88 ng/ml +/- 0.29 ng/ml, respectively), so did vWF level (101.2% +/- 4.68%, 104.3% +/- 5.78%, and 127.7% +/- 5.74%, respectively). STM level was much higher in acute rejection than that in chronic rejection (7.88 ng/ml +/- 0.29 ng/ml vs. 6.35 ng/ml +/- 0.54 ng/ml, t = 2.46, P < 0.05), in no reaction group after impacting therapy than in effective group (8.30 ng/ml +/- 0.19 ng/ml vs. 3.82 ng/ml +/- 0.22 ng/ml, t = 12.98, P < 0.01), and in dead group after treatment than in living group (7.98 ng/ml +/- 0.18 ng/ml vs. 6.51 ng/ml +/- 0.41 ng/ml, t = 3.39, P < 0.01). CONCLUSIONS: Plasma STM and vWF can be taken as laboratory items for monitoring liver transplantation rejection. Plasma STM can act as not only an early prognosticating marker, but also suitable to distinguish acute from chronic reject reaction, and as a marker for monitoring impacting therapy effect and judging prognosis.

Adolescent↗
PubMed2003

Inhibition on telomerase activity and cytotoxic effects by cisplatin in cultured human choroidal melanoma cells.

PURPOSE: To study the changes of telomerase activity and cytotoxic effects by Cisplatin; cis-dichlorodiamine platinum (CDDP) in cultured human choroidal melanoma. MATERIAL AND METHODS: The primary cultured human choroidal melanoma cells were cultured in the presence and absence of CDDP with different concentration and time respectively. The toxic effects were evaluated by MTT and the level of telomerase was detected by PCR-ELISA assay. And the relationship between telomerase activity and cytotoxic effects were analyzed by a correlation analysis. RESULTS: Following the increase of the concentration and the time of CDDP, gradually repressed telomerase activity was detected in cultured cells. Meanwhile, the restrain rate of the cells increased. The telomerase activity at 24 h and 1 microgram/ml was repressed significantly compared with the control cells. However, the appearance of cell death lagged behind the decreasing of telomerase. CONCLUSIONS: CDDP is an effective telomerase inhibitor in cultured choroidal melanoma cells of human eyes, which presents concentration and time dependency and can cause the death of cultured cells.

Adult↗
PubMed2003

[A study on sarcosaphagous insects species variety with seasons in Chengdu].

OBJECTIVE: To study the species of sarcosaphagous insects. METHODS: Rabbits were killed and placed outdoors from March to November. Flies that appeared the cadavers were observed and identified. RESULTS: There are five main flies, i.e., Muscadomesticauicina, Lucilia sericata, C. Megacephala, S. fuscicauda, Aldrichiragrahormi. From midtime of April to the beginning of October, Muscadomesticauicina could be seen on the cadvers, however, Aldrichiragrahormi only could be seen before the beginning of May. Otherwise, Lucilia sericata, C. Megacephala, S. fuscicauda could be seen on the cadvers from March to the end of October. After the midtime of November, none of sarcosaphagous flies could be seen on the cadvers. On the other hand, maggots of sarcosaphagous flies could be seen often on the cadvers after adults of sarcosaphagous flies intruding 1 to 4 days, relating to temperature of environment. CONCLUSION: If these flies history of life be studied. it is useful for estimating postmortem interval in Chengdu.

Animals↗
PubMed2003

[Organic acids conversion in methanogenic-phase reactor of the two-phase anaerobic process].

Experiments on organic acids conversion in methanogenic-phase of the two-phase anaerobic process were conducted. The results showed that when the acidogenic-phase was in mixed acids fermentation and its load was 41.5 kg/(m3-d), the load of methanogenic-phase was 6.05 kg/(m3.d), the substrate conversion velocity of bacteria inhabited at the same height of UASB reactor as follows: acetic acid > ethanol > butyric acid > propionic acid; ethanol-utilized microbial had the same pH range as methanogenic bacteria; ethanol-type fermentation was the optimal acidogenci-type fermentation for the two-phase anaerobic process; the conversion of acetic acid was rather high, but the others organic acids will be convert to acetic acid make it the rate-limiting step for anaerobic degradation.

Acetic Acid↗
PubMed2003

[Prevalence of vitamin A deficiency in children under six years of age in Tibet, China].

OBJECTIVE: To understand the prevalence of vitamin A deficiency (VAD) among children under six years of age in Tibet, China. METHODS: Totally, 1 257 children under six years of age were selected from two cities, two farming counties, two semi-farming counties and two livestock farming counties with stratified cluster sampling to asses VAD status in Tibet. Family information, children's feeding and disease history in the previous two weeks were collected by questionnaire. Blood specimen was collected from each child and serum was separated for detection of vitamin A concentration with microfluorescent spectrophotometry. RESULTS: Totally, 1 257 children under six years of age were surveyed, with 635 boys, 622 girls, 862 aged over two years, and 98.5% of Tibet nationality. Six cases of night blindness and two cases of xerophthalmia were detected from them, with prevalence of clinical VAD of 0.96%. Eighteen of 1071 mothers with children under six years of age were found suffering from night blindness, accounting for 1.7%. Clinical cases of VAD both in children and mothers came from all four sampling strata. Average serum concentration of vitamin A and prevalence of subclinical VAD (serum vitamin A lower than or equal to 0.70 micromol/L) was 1.15 micromol/L and 5.4% and 1.12 micromol/L and 4.7% in cities and livestock farming counties, respectively, significantly higher than those in farming (1.04 micromol/L and 11.0%) and semi-farming counties (1.05 micromol/L and 12.3%), respectively, as compared to average levels of 1.09 micromol/L and 8.4% in the autonomous region as a whole. Prevalence of subclinical VAD in children under six months and those aged six to eleven months were 22.2% and 13.3%, respectively, significantly higher than those in children aged one year (8.5%), two to three years (5.4%) and four to five years (7.9%), respectively. There was also significant difference in serum level of vitamin A between children at varied ages, but no significant difference both in serum level of vitamin A and prevalence of subclinical VAD between gender was found. CONCLUSIONS: In general, status of VAD in children of Tibet was milder than that at national level. But, moderate subclinical VAD in some areas, such as farming and semi-farming counties, did exist, so vitamin A supplementation aiming to children, especially those under one year of age, in those areas should be urged.

Age Factors↗
PubMed2003

[Study of the inhibiting effect of anti-NKG2D polyclonal antibody on cytotoxicities of NK and LAK cells].

AIM: To investigate the effect of anti NKG2D polyclonal antibody(pAb) on cytotoxicities of NK and LAK cells. METHODS: Peripheral blood mononuclear cells(PBMCs) were separated by centrifugation on Ficoll-Hypaque gradients. LAK cells were induced from PBMCs by PHA (10 mg/L) and rhIL-2 (1x10(6)U/L). Then NK cells were sorted by flow cytometry(FCM). The cytotoxicities of NK and LAK cells were analyzed by MTT colorimetry after NKG2D molecule on NK and LAK cells were blocked with anti-NKG2D pAb. RESULTS: FCM analysis proved that both purity and activity of obtained NK cells were high.The anti-NKG2D pAb could inhibit significantly cytotoxicities of NK and LAK cells to K562 and HepG2 cells, for NK cells,having decreased 82.9% and 75.6%, for LAK cells,having decreased 52.8% and 50.2%, respectively.The anti-NKG2D pAb had no effect on cytotoxicities of NK and LAK cells to CNE cells. CONCLUSION: The anti-NKG2D pAb can inhibit cytotoxocities on tumor cells by NK and LAK cells through NKG2D molecule on two effector cells.

Cytotoxicity, Immunologic↗
PubMed2003

[Study on anatomy of anterior tibial tendon and its clinical application].

OBJECTIVE: To observe the normal and abnormal insertions of the anterior tibial tendon and store up knowledge for clinical application. METHODS: Forty-six antiseptic specimens of the foot of Chinese were selected for anatomical and histological studies on the insertions. The methods included taking the photos, adding up the numbers of the insertions that mainly attach to the first metatarsal os or the medial cuneiform os and measuring the length of the tendons from the line connecting the malleolus lateralis projection and malleolus medialis projection to the insertion. RESULTS: The insertions could be categorized as three types: 28 (60.87%) insertions belonged to the bundle type; 14 (30.43%) insertions were of the medial type; 4 (8.7%) insertions were of the bifurcate type. 40 insertions mainly attached to the medial cuneiform os; 6 insertions mainly attached to the first metatarsal os. The length of the anterior tibial tendon of adults was determined to be 72.33 +/- 5.29 mm and the length of the children's tendon 56.77 +/- 4.54 mm. CONCLUSION: The aboved finding suggest that in clinical treatment the insertions of the bifurcate type should be cut off completely as the anterior tibial tendons of the bifurcate type are transferred into the lateral part of the feet. The insertions of the bundle type and bifurcate type are not suitable for the split anterior tibial tendon transfer, but the medial type cases are suitable for this kind of operation.

Clubfoot↗
PubMed2003

[Construction of recombinant eukaryotic expression vector of NKG2D gene and its expression in COS-7 cells].

OBJECTIVE: To construct recombinant eukaryotic expression vector of NKG2D, and to examine its expression in COS-7 cells. METHODS: Human NKG2D cDNA was obtained from peripheral blood mononuclear cells using RT-PCR, and then the target gene was cloned into pMD18-T vector. A eukaryotic expression plasmid containing target gene was constructed by DNA recombinant technique, and was confirmed by double restriction enzymes digestion and DNA sequence analysis. The recombinant plasmid with encapsuled lipofectamine was transfected into COS-7 cells, and the transfected COS- The 7 cells containing expressive target gene were confirmed by RT-PCR and flow cytometry. RESULTS: The sequence of NKG2D cDNA obtained from the recombinant eukaryotic expression vector was identical with that published on GeneBank. The NKG2D gene was expressed successfully in COS-7 cells. CONCLUSION: The recombinant expression plasmid containing NKG2D gene is constructed successfully. After being transfected to COS-7 cells, the NKG2D protein is expressed by the engineering COS-7 cells line, which lays a foundation for further studying biological activity of NKG2D.

Animals↗
PubMed2002

Versatile regulation of cytosolic Ca2+ by vanilloid receptor I in rat dorsal root ganglion neurons.

Analysis of small dorsal root ganglion (DRG) neurons revealed novel functions for vanilloid receptor 1 (VR1) in the regulation of cytosolic Ca(2+). The VR1 agonist capsaicin induced Ca(2+) mobilization from intracellular stores in the absence of extracellular Ca(2+), and this release was inhibited by the VR1 antagonist capsazepine but was unaffected by the phospholipase C inhibitor xestospongins, indicating that Ca(2+) mobilization was dependent on capsaicin receptor binding and was not due to intracellular inositol-1,4,5-trisphosphate generation. Confocal microscopy revealed extensive expression of VR1 on endoplasmic reticulum, consistent with VR1 operating as a Ca(2+) release receptor. The main part of the capsaicin-releasable Ca(2+) store was insensitive to thapsigargin, a selective endoplasmic reticulum Ca(2+)-ATPase inhibitor, suggesting that VR1 might be predominantly localized to a thapsigargin-insensitive endoplasmic reticulum Ca(2+) store. In addition, VR1 was observed to behave as a store-operated Ca(2+) influx channel. In DRG neurons, capsazepine attenuated Ca(2+) influx following thapsigargin-induced Ca(2+) store depletion and inhibited thapsigargin-induced inward currents. Conversely, transfected HEK-293 cells expressing VR1 showed enhanced Ca(2+) influx and inward currents following Ca(2+) store depletion. Combined data support topographical and functional diversity for VR1 in the regulation of cytosolic Ca(2+) with the plasma membrane-associated form behaving as a store-operated Ca(2+) influx channel and endoplasmic reticulum-associated VR1 possibly functioning as a Ca(2+) release receptor in sensory neurons.

Animals↗
PubMed2002

Receptor-selective effects of endogenous RGS3 and RGS5 to regulate mitogen-activated protein kinase activation in rat vascular smooth muscle cells.

Regulators of G protein signaling (RGS) proteins compose a highly diverse protein family best known for inhibition of G protein signaling by enhancing GTP hydrolysis by Galpha subunits. Little is known about the function of endogenous RGS proteins. In this study, we used synthetic ribozymes targeted to RGS2, RGS3, RGS5, and RGS7 to assess their function. After demonstrating the specificity of in vitro cleavage by the RGS ribozymes, rat aorta smooth muscle cells were used for transient transfection with the RGS-specific ribozymes. RGS3 and RGS5 ribozymes differentially enhanced carbachol- and angiotensin II-induced MAP kinase activity, respectively, whereas RGS2 and RGS7 ribozymes had no effect. This enhancement was pertussis toxin-insensitive. Thus RGS3 is a negative modulator of muscarinic m3 receptor signaling, and RGS5 is a negative modulator of angiotensin AT1a receptor signaling through G(q/11). Also, RGS5 ribozyme enhanced angiotensin-stimulated inositol phosphate release. These results indicate the feasibility of using the ribozyme technology to determine the functional role of endogenous RGS proteins in signaling pathways and to define novel receptor-selective roles of endogenous RGS3 and RGS5 in modulating MAP kinase responses to either carbachol or angiotensin.

Animals↗
PubMed2002

Solvent kinetic isotope effects monitor changes in hydrogen bonding at the active center of yeast pyruvate decarboxylase concomitant with substrate activation: the substituent at position 221 can control the state of activation.

Substrate activation of yeast pyruvate decarboxylase has been studied extensively in the authors' laboratories providing strong evidence that interaction of substrate with residue C221 provides the trigger, and the information is then transmitted along the C221 to H92 to E91 to W412 to G413 pathway to the 4'-amino nitrogen of the thiamin diphosphate cofactor. Earlier, it was found that the C221S substitution reduced the Hill coefficient from 2.0 to 0.8-0.9, the C221A substitution to 1.0, even though C221 is located on the beta domain some 20 A from the active center thiamin diphosphate cofactor, which is at the interface of the alpha and gamma domains. Here are reported experiments on the C221D/C222A and C221E/C222A variants, in which a negative charge is built onto the C221 side chain, to better mimic the effect of a pyruvate molecule covalently bonded to C221 as a thiohemiketal. Both variants were purified to an optimal activity of 70% of the wild-type enzyme, higher activity than that with the earlier uncharged substitutions at this position. The Hill coefficient for both variants is exactly 1.0. The deuterium solvent kinetic isotope effects (SKIE) on k(cat) for these variants were similar to that for the wild-type enzyme and the C221A/C222A variant, suggesting that starting with the first irreversible step (decarboxylation) the rate-limiting transition states are very similar for all of these enzyme forms. In contrast, such SKIE on k(cat)/K(m) are quite different for the C221A/C222A variant (0.62) than for the C221E/C222A or C221D/C222A variants (0.80-0.82), clearly indicating the effect of the C221 substitutions on transition states starting with the binding of the first substrate to the enzyme and terminating with the decarboxylation step. The results provide strong additional evidence for the involvement of residue C221 in the substrate activation process and suggest that the C221D (C221E) substitution shifts the enzyme into a conformation that resembles the activated conformation. A comparison with SKIE for the wild-type enzyme provides insight to changes in hydrogen bonding at the active center as a result of substrate activation.

Binding Sites↗