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Biomedical subjects

Q Liu

Publications and source records attributed to Q Liu.

At least 433 records · Page 24Linked to original sources
PubMed1998

Sequence variation in the small-subunit rRNA gene of Plasmodium malariae and prevalence of isolates with the variant sequence in Sichuan, China.

By two PCR-based diagnostic methods, Plasmodium malariae infections have been rediscovered at two foci in the Sichuan province of China, a region where no cases of P. malariae have been officially reported for the last 2 decades. In addition, a variant form of P. malariae which has a deletion of 19 bp and seven substitutions of base pairs in the target sequence of the small-subunit (SSU) rRNA gene was detected with high frequency. Alignment analysis of Plasmodium sp. SSU rRNA gene sequences revealed that the 5' region of the variant sequence is identical to that of P. vivax or P. knowlesi and its 3' region is identical to that of P. malariae. The same sequence variations were also found in P. malariae isolates collected along the Thai-Myanmar border, suggesting a wide distribution of this variant form from southern China to Southeast Asia.

Animals↗
PubMed1998

Acute effects of triiodothyronine on glucose and fatty acid metabolism during reperfusion of ischemic rat hearts.

Clinical studies have demonstrated improved myocardial recovery after severe ischemia in response to acute triiodothyronine (T3) treatment. We determined whether T3 improves the recovery of ischemic hearts by improving energy substrate metabolism. Isolated working rat hearts were perfused with 5.5 mM glucose and 1.2 mM palmitate and were subjected to 30 min of no-flow ischemia. Glycolysis, glucose oxidation, and palmitate oxidation were measured during aerobic reperfusion by adding [5-3H]glucose, [U-14C]glucose, or [9,10-3H]palmitate to the perfusate, respectively. During reperfusion, cardiac work in untreated hearts recovered to a lesser extent than myocardial O2 consumption (MVO2), resulting in a decreased recovery of cardiac efficiency, which recovered to only 25% of preischemic values. Treatment of hearts with T3 (10 nM) before ischemia increased glucose oxidation during reperfusion, which was associated with a significant increase in pyruvate dehydrogenase (PDH) activity, the rate-limiting enzyme for glucose oxidation. In contrast, T3 had no effect on MVO2, glycolysis, or palmitate oxidation. This resulted in a significant decrease in H+ production from glycolysis uncoupled from glucose oxidation (2.7 +/- 0.3 and 1.9 +/- 0.3 micromol . g dry wt-1 . min-1 in control and T3-treated hearts, respectively, P < 0.05), as well as a 3.2-fold improvement in cardiac work and a 2.3-fold increase in cardiac efficiency compared with untreated postischemic hearts (P < 0.05). These data suggest that T3 can exert acute effects that improve the coupling of glycolysis to glucose oxidation, thereby decreasing H+ production and increasing cardiac efficiency as well as contractile function during reperfusion of the postischemic heart.

Analysis of Variance↗
PubMed1998

Urban residentship and return migration to Shanghai in the aftermath of the cultural revolution.

"Young people were sent to the countryside during the Cultural Revolution and were later allowed to return home in the 1970s. This paper examines the return migration of Chinese youth from the countryside based on officially sanctioned reasons and grounds. The most often used reasons or grounds were in fact claims to urban residentship arising from connections to the city by previous residence, by birth and by family. Claimants negotiated with the state in a cultural language which rationalizes the claimed needs in terms of traditional social codes. The study reveals that the passive and submissive image the Chinese civil society outwardly present is deceptive. Their claims, however, still fall short of modern social citizenship."

Asia↗
PubMed1998

Cell specific expression of the sst2A and sst5 somatostatin receptors in the rat anterior pituitary.

Somatostatin (SRIF), originally described as a hypothalamic hormone that inhibits the release of growth hormone was subsequently shown to inhibit the secretion of multiple pituitary hormones. Five genes encoding six different SRIF receptors (sst1, 2A, 2B, 3, 4 and 5) have been cloned and mRNAs for all five are expressed in the anterior pituitary. We used double immunostaining to determine which cells in the anterior pituitary bear sst2A and sst5 receptors. Our results show that these two receptors are widely distributed in the pituitary gland and are both present in a large percentage of GH cells. In addition, sst5 occurs in a small population of corticotrophs and a large percentage of lactotrophs whereas sst2A is found in only a few lactotrophs but a large number of corticotrophs. The sst2A receptor is also expressed in about a third of the gonadotrophs and thyrotrophs. Interestingly, sst2A and sst5 receptors colocalize in a small percentage of cells, most likely somatotrophs demonstrating that the same cells can contain multiple sst receptor subtypes. These results indicate that sst subtype specific analogs are likely to be useful for the selective regulation of individual pituitary hormones.

Animals↗
PubMed1998

[The effects of interferon-alpha on oxygen radical production by human neutrophils].

This study was done to determine if the production and metabolism of reactive oxygen species from human neutrophils were modulated by the treatment of interferon-alpha (IFN-alpha). Luminol-dependent Chemiluminescence (LmCL) responses were inhibited by a high concentration of IFN-alpha (more than 1 x 10(4) IU/ml) when opsonized zymosan (OZ) and phorbol 12-myristate 13-acetate (PMA) were used as stimulants. However, these responses were increased by 1 x 10(3) IU/ml of IFN-alpha with Ca(2+)-ionophore A23187 stimulation. Lucigenin-dependent Chemiluminescence (LgCL) responses were inhibited by all concentrations. These findings suggest the possibility that IFN-alpha inhibits activation of protein kinase C (PKC), whereas the resulting effect might be due to the inhibition of myeloperoxidese (MPO) degranulation. Preincubation of human neutrophils with IFN-alpha for 30, 60 or 120 minutes and subsequent stimulation with OZ, PMA and Ca(2+)-ionophore A23187 caused an increase LgCL responses, while inhibiting LmCL responses. These findings suggest that preincubation of human neutrophils with a high concentration of IFN-alpha might enhance the NADPH-oxidase activity, although a relative increase of LgCL was due to the inhibition MPO degranulation.

Acridines↗
PubMed1998

Health-promoting behaviors of rural adolescent women.

A part of a larger study of the health behaviors of adolescent women, this investigation examined health-promoting behaviors and the influence of cognitive, social, and environmental factors on these health-promoting behaviors of rural adolescent women. The sample consisted of 128 rural African-American and white adolescent women. Forty-four percent of the variance in health-promoting behavior of this sample was explained by five variables: self-image, problem solving, mother's education, employment status, and family structure. Self-image was the most salient predictor of health-promoting behavior, explaining 33% of the variance.

Adolescent↗
PubMed1998

Denaturation fingerprinting: two related mutation detection methods especially advantageous for high G + C regions.

Two versions of denaturation fingerprinting (dnF2R and dnF1R are described for detecting mutations. DnF2R is a sensitive screening method in which fingerprints are generated by performing denaturing gel electrophoresis on bidirectional "cycle-sequencing" reactions with each of two dideoxy terminators, e.g. ddATP and ddCTP. When the fingerprints generated by ddATP and ddCTP are combined, all sequence changes are expected to result in one extra and one absent segment. DnF2R was performed on 246- and 318-bp segments of the human factor IX gene, and the products were electrophoresed through a 6% Long Ranger gel with 7 M urea. All 32 single-base mutations were detected in hemizygous males with hemophilia B. DnF2R has been applied to detect a total of seven heterozygous sequence changes in large-scale screening and was found to be especially suitable for high G+C regions. In a blinded analysis, all of twenty-four additional single-base mutations were detected, but 7 of 31 heterozygous mutations were missed (23%). To reduce the effort of dnF2R by almost twofold while retaining the ability to detect all types of single-base changes, one fingerprint (dnF1R) was generated by performing a single reaction with ddATP and a second chemically modified terminator (e.g., ROX-conjugated ddCTP), which retards the mobility of the same termination products. The sensitivity and specificity of dnF1R equaled that of dnF2R, with the exception that the blinded analysis of heterozygotes in the 318-bp segment, which revealed the presence of an additional mutation. DnF under partially denaturing conditions may have optimal sensitivity for the detection of heterozygotes.

DNA Fingerprinting↗
PubMed1998

Subcycling-PCR for multiplex long-distance amplification of regions with high and low GC content: application to the inversion hotspot in the factor VIII gene.

Previously we described a PCR protocol for detecting the inversion in the factor VIII gene, which is a common cause of Hemophilia A. This PCR assay is challenging due to the size of the amplification (10-12 kb), the varying GC content (30%-80%) and the multiplex PCR products involved (four for carrier female). Efficient amplification of the four segments depends on three unusual modifications to standard long-distance PCR protocols: (i) very high concentrations of dimethyl sulfoxide, (ii) addition of deaza-dGTP and (iii) high concentration of Taq and Pwo DNA polymerases. One of the segments was amplified much more efficiently than the others under standard three-temperature cycling conditions (12 s at 94 degrees C, 30 s at 65 degrees C and 14 min at 68 degrees C). To facilitate the uniform amplification of the multiple regions, subcycling-PCR (S-PCR) was developed. In S-PCR, the combined annealing/elongation step is composed of subcycles of shuttling between a low and a high temperature, e.g., shuttling four times between 60 degrees and 65 degrees C. S-PCR produces consistent robust amplification of the various segments produced by wild-type, mutant and carrier individuals. S-PCR is a simple generalization of PCR, which generally may be advantageous in three contexts: (i) amplification of long segments in which the GC content varies within the segment, (ii) multiplex amplification of long segments and (iii) multiplex amplification of short segments in which the GC content varies among the segments.

Chromosome Inversion↗
PubMed1998

Allelic diversity at the merozoite surface protein-1 locus of Plasmodium falciparum in clinical isolates from the southwestern Brazilian Amazon.

Nucleotide sequences of each variable block in the Plasmodium falciparum merozoite surface protein-1 gene (PfMSP-1) may be grouped into one of two or three possible allelic types, named after the reference isolates MAD20, K1, and RO33. Allelic diversity at this locus basically results from different combinations of allelic types in variable blocks. We used a polymerase chain reaction (PCR)-based strategy to type the variable blocks 2, 4a, 4b, and 10 of the PfMSP-1 gene of P. falciparum isolates from 54 symptomatic malaria patients living in Rondonia, a hypoendemic area in the southwestern Brazilian Amazon. Ten different PfMSP-1 gene types, defined as unique combinations of allelic types in variable blocks, were identified among the 54 isolates. Twenty-one isolates (39%) harbored more than one gene type and two had at least three genetically distinct clones. Hybrid sequences, with a MAD20-type sequence in the 5' segment (4a) and a K1-type sequence in the 3' segment (4b), were quite common in block 4. Direct sequencing of block 4 PCR products revealed a new putative recombination site in four isolates. In contrast with previous studies, the observed distribution of gene types does not deviate significantly from that expected under the null hypothesis of random association between allelic types detected in each variable block. These contradictory data are discussed with reference to the immunoepidemiologic features prevailing in distinct malaria-endemic areas.

Adolescent↗
PubMed1998

Protective effect of apolipoprotein A I, A II, C I and C II on endothelial cells injury induced by low density lipoprotein.

OBJECTIVE: To investigate the protective effect of apo-lipoprotein (apo) A I, A II, C I and C II, the main proteins in high density lipoprotein (HDL), on the morphology and function of human umbilical vein endothelial cells injured with low density lipoprotein (LDL) in vitro. METHODS: Cultured human endothelial cells derived from umbilical veins were exposed to LDL, HDL, and apoA I, A II, C I and C II. The morphology of endothelial cells was examined with phase contrast and transmission electron microscope. The released amount of lactate dehydrogenase (LDH) and 6-keto-prostaglandin F1 alpha (PGF1 alpha) was also measured. RESULTS: Endothelial cells after being injured by LDL showed cell contraction, increased release of LDH and decreased secrection of prostacyclin (PGI2). However, the addition of HDL, and apoA I, A II, C I and C II before incubation with LDL inhibited the cellular injury induced by LDL as demonstrated by lowered LDH release, increased level of PGF1 alpha and prevention of morphological changes. CONCLUSION: The results indicate that apoA I, A II, C I and C II, as well as HDL, may play an important role in combating atherogenesis by protecting endothelial cells from damages induced by LDL.

Apolipoprotein A-I↗
PubMed1998

[One-stage vagina reconstruction using the pudendal-thigh skin flap].

OBJECTIVE: This is to introduce a method for vagina reconstruction using the pudendal-thigh skin flap. METHODS: The pudendal-thigh skin flap has been used for vagina reconstruction in 70 cases since 1989. RESULTS: All the operations were successful and the method has become a mature technique. CONCLUSION: The advantages of the method are 1. the reconstructed vagina has good sensation and stable in maintaining its dimensions; 2. the linear scars of the donor site are hidden and inconspicuous; 3. the appearance of the perineum looks well; 4. the procedure is simple and favors its application.

Adolescent↗
PubMed1998

[Effects of blocking CD18-mediated leukocyte adhesion on the survival of the island flap].

OBJECTIVE: This study was to investigate the role of leukocyte and leukocyte adhesion in tissue injury from ischemia and reperfusion. METHODS: The experiment utilized the monoclonal antibody (mAb) directed to the leukocyte adhesion glycoprotein CD18 to block leukocyte adhesion and aggregation in an island flap model in rats. Tissue content of myeloperoxidase (MPO) and malondialdehyde (MDA) were detected after transient treatment with either saline or mAb directed to CD18. Flap survival was assessed 7 days afterwards. RESULTS: The content of both MPO and MDA was significantly increased with 8 h ischemia and 1 h reperfusion of the flap. The treatment with anti-CD18 mAb significantly decreased the levels of MPO and MDA and also significantly improved the survival of flaps compared with the saline-treated controls. CONCLUSION: CD18-mediated leukocyte adhesion plays an important role in tissue injury from ischemia and reperfusion. Blocking leukocyte adhesion can attenuate leukocyte-mediated injury, providing protective effects on island flaps.

Animals↗
PubMed1998

[Protective effects of shenmai cardioplegia on intracardiac operative patients with cardiopulmonary bypass].

Forty intracardiac-operative patients were divided into two groups randomly. Twenty patients were received by the improved St. Thomas Crystal Blood (1:4) Cardioplegia(Group A); 20 by the Shenmai liquid and improved St. Thomas Crystal Blood(1:4) Cardioplegia(Group B). During perioperation, the blood samples and myocardial tissue were collected, and clinical observations were recorded. The results showed that in Group B, contents of myocardial specific isoenzyme of creatine kinase(CK-MB), lactate dehydrogenase(LDH), malonyldialdehyde(MDA), and myocardial Ca2+ were significantly lower, the contents of superoxide dismutase(SOD) were, significantly better than that in Group A; and the histological findings showed less damage in Group B than in Group A. We conclude that Shenmai Cardioplegia can increase the myocardial protection of the intracardiac-operative patients. The possible mechanisms are that Shenmai liquids inhibit the production of oxygen free radicals and calcium paradox.

Adolescent↗
PubMed1998

[The effect of brain-derived neurotrophic factor on the rat electroretinography after pressure-induced ischemic injury].

Brain-derived neurotrophic factor (BDNF) or normal goat serum (NGS) was injected intravitreously in each 11 wistar albino rats two days before the induction of ischemia. Retinal ischemia was induced in 22 rats by increasing intraocular pressure to the threshold level which extinguished the electroretinography (ERG) b-wave individually, and maintaining for 90 minutes. The ERG b-wave of the BDNF-treated rats recovered to 80.5 +/- 24.4% of their normal amplitude three days after ischemia, while that of the NGS-treated rats recovered only to 11.1 +/- 5.3%. Statistic analysis showed that the recovery level of ERG b-wave after ischemia in the BDNF and NGS treated rats was significantly different (P < 0.01). The results suggest that BDNF could promote the recovery of the retinal electrophysiologic function from ischemia induced by high intraocular pressure.

Animals↗
PubMed1998

[Protection of vitamin E against testis lipid peroxidation induced by iron and ethanol].

The influence of acute iron and ethanol load on lipid peroxidation and antioxidative defense systems in rat testes and the modification after supplemented with Vitamin E was investigated. Acute iron and ethanol load was achieved by i.p. injection of iron-dextran (500 mg/kg) and ethanol (50 mmol/kg). After 18 h, a significant increase in testis total iron content was induced. Compared with control, total testis iron content was 6.8-fold higher in iron-treated rats and 9.1-fold in iron and ethanol treated rats. As the content of iron increasing, the endogenous lipid peroxidation evaluated as 2-thiobarbituric acid-rective substances (TBARS) increased apparently, and the content of lipid-soluble antioxidants alpha-tocopherol decreased. The supplement of an antioxidant, alpha-tocopherol, protected against lipid peroxidation. Iron and ethanol treatment did not affect the activity of superoxide dismutase, catalase and glutathione peroxidase. The results indicate that acute iron load causes iron accumulation in rat testes and ethanol increases the same accumulation. Iron played pivotal paracrine roles on ethanolinduced injure rat testis. The supplement of Vitamin E can protect against this damage.

Animals↗
PubMed1998

[Experimental study of apoptosis induced by cisplatin in human ovarian carcinoma AO 10/17 cells].

OBJECTIVE: Whether apoptosis induced by cisplatin resulted in tumor growth inhibition and the relationships between apoptosis and cell cycle, intracellular and extracellular Ca++ concentration were investi- gated. METHODS: AO 10/17 cells were treated with cisplatin. Morphological changes (HE stain) were observed under light microscope; DNA degradation was assayed by electrophoresis on agarose gel. The change of cell cycle was analyzed by flow cytometer and cytosolic Ca++ concentrations were monitored using probe of calcium ion fluo-3/AM. RESULTS: Under the influence of cisplatin, AO 10/17 cells exhibited changes of apotosis both in morphology and in the characteristics of electrophoresis. Meanwhile the cell cycle also showed special change and intracellular Ca++ concentration was increased. Increase in extracellular Ca++ concentration when AO 10/17 cells were treated with CaCl2 and cisplatin did not enhance the efficacy of cisplatin. CONCLUSION: The results suggest that apoptosis followed by change of cytosolic Ca++ concentration is one of the mechanism of cisplatin in inhibition of ovarian tumor growth. It is closely related to cell cycle.

Antineoplastic Agents↗