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Biomedical subjects

L Liu

Publications and source records attributed to L Liu.

At least 1,027 records · Page 57Linked to original sources
PubMed1995

[Clinical observation on vertical transmission of human papillomavirus].

OBJECTIVE: To observe the possibility of maternal-fetal vertical transmission of human papillomavirus (HPV) via amniotic fluid. METHODS: Specimens of cervical secretions from 30 pregnant women were obtained during the third trimester before rupture of membrane, and specimens of pharyngeal secretions of their neonates were obtained 12-48 hours after birth. Amniotic fluids were collected in 13 pregnant women during cesarean section. The presence of HPV types 6, 11, 16, 18, 31, 33, 35, 38 deoxyribonucleic acid were detected by consensus polymerase chain reaction. RESULTS: HPV deoxyribonucleic acid was found in 16 cervical specimens, 14 pharyngeal specimens and in 3 amniotic fluids, the positive rate was 53.3%, 46.7%, 23.1% respectively. The pharyngeal specimen was also HPV positive in one of the three neonates from the amniotic fluid positive mothers. CONCLUSION: The results indicate that HPV can be transmitted in utero through amniotic fluid and cesarean section can not protect the neonates against vertical transmission completely.

Adult↗
PubMed1995

Research of the exploitation of human resources in blind prevention and primary eye care.

PURPOSE: This research studied how to establish a relatively advanced blindness prevention and eye care cause in economically underdeveloped countryside. METHODS: Ophthalmic vocational schools and professional lectures were held to train "practical type" primary eye care workers for the countryside. Further study in high-level (above provincial) hospitals was taken to train blindness prevention & eye care backbones and leaders. RESULTS: In 1986, the ratio of the number of the eye care workers of all levels to the number of the whole population in the prefecture was 1:26,000. In 1992, it rose to 1:17,000. An eye care network of 222 stations had been established in the countryside. Ten in the 13 county hospitals had a seperated ophthalmology department, in which 3 were awarded "National advanced blindness prevention County". Twenty one hospitals were appointed as the Unit of Surgical Vision-Rehabilitation of Cataract. Blindness prevention and eye care covered 1,000,000 population (eye care available within 5 kilometers), 23.5% of the whole population. CONCLUSIONS: In a demographically large but economically underdeveloped countryside area, the key to wide-range blindness prevention and eye care is to exploit human resources effectively. We should train "Practical type" primary eye care workers, and have a number of department leaders who are authoritive, influential in this field and ready to sacrifice to this cause.

Blindness↗
PubMed1995

[Clinical significance of detection of plasma fibronectin in respiratory failure].

Plasma fibronectin (PFn) level was measured with immumoelectrophoresis in 40 healthy adults and 174 patients (221 person-times) with respiratory insufficiency (R I). The levels of PFn in 40 healthy adults, 85 person-times of R I, 27 person-times of Type I respiratory failure (RF I), 82 person-times of RF II, and 27 person-times of iatrogenic RF (IRF) were 292.48 +/- 43.11 mg/L, 253.12 +/- 67.00 mg/L 141.97 +/- 70.84 mg/L, 180.48 +/- 49.96 mg/L and 263.49 +/- 70.05 mg/L respectively. The levels of PFn of patients with R I, RF I and RF II were significantly lower than that in healthy adults (P < 0.001). The level of PFn of patients with TRF was significantly lower than that in healthy adults (P < 0.05). There was positive correlation between the levels of PFn and PaO2 in 221 person-times of R I (r = 0.5358, P < 0.001), RF I r = 0.3822, P < 0.05). RF II (r = 0.3050, P < 0.01), and IRF (r = 0.4963, P < 0.02). There was negative correlation between the levels of PFn and PaCO2 in 221 person-times of R I (r = -0.2053, P < 0.005) and RF II (r = -0.2181, P < 0.05). In 34 patients with RF, the PFn before treatment was significantly lower than that two weeks after treatment (147.80 +/0 61.59 mg/L vs 214.56 +/- 56.12 mg/L) (P < 0.001). Among 33 cases of RF whose level of PFn was < 150 mg/L, 18 cases complicated multiple system organ failure and 4 cases complicated adult respiratory distress syndrome. The average level of PFn in 3 death cases was lower than 100 mg/L. It is suggested that PFn level might be used as an index in making early diagnosis, monitoring RF and predicating progosis of RF.

Adolescent↗
PubMed1995

Nuclear remodelling and early development in cryopreserved, porcine primordial germ cells following nuclear transfer into in vitro-matured oocytes.

Nuclear transfer was conducted in the pig using, as karyoplasts, primordial germ cells which had been cryopreserved. The cytoplasts were presumptive S- or MII-phase, in vitro-matured oocytes, which had been enucleated mechanically. Enucleation was effective in 94.3% of cases. Karyoplasts were introduced into the perivitelline space, in close contact with the cytoplasts, and the complexes fused by electrical stimulation and activation. Activation was successful in 82-88% of nonmanipulated, pulsed oocytes, and in 55% of germ cell-oocyte complexes. The reconstituted embryos were examined for nuclear remodelling and cleavage in vitro. Nuclear swelling was more prominent when MII-phase cytoplasts, rather than S-phase, cytoplasts, were used. After 24 h in culture, the cleavage rate was not significantly different whether blastomeres or primordial germ cells were used as karyoplasts, and whether MII-phase or S-phase cytoplasts were used. However, after 72 h in culture, the developmental rate was higher when MII-phase cytoplasts (75%) were used for the recipients of blastomeres compared with S-phase cytoplasts (38.5%, p < 0.05). Similar tendencies were observed with germ-cell nuclear transfer when inositol was used as medium for electrofusion (60% vs 27.8%, p < 0.05). Furthermore, when MII-phase cytoplasts were used, the nuclear transferred embryos derived from blastomeres developed at a significantly higher rate than from primordial germ cells (37.5%, p < 0.05). We conclude that cryopreserved primordial germ cells are competent to undergo nuclear remodelling and cleavage during 72 h or incubation in vitro to the 4-cell stage, following nuclear transfer to enucleated, activated (S-) or MII-phase oocytes. This experimental system may help to elucidate events in the early development of pig embryo following nuclear transfer using germ cells as karyoplasts.

Animals↗
PubMed1995

[Gene diagnosis and carrier detection of hemophilia B by using genomic amplification with transcripts sequencing].

Using GAWTS technique (genomic amplification with transcripts sequencing), we studied germline mutation patterns of 36 hemophilia B patients from the mainland of China. Some distinctions between Chinese and USA caucasians were found. The GAWTS was strongly recommanded to be used in the direct genomic sequencing as a good technique. Seventeen carriers were identified.

Asian People↗
PubMed1995

[An investigation into antibiotic resistance and plasmid pattern of Enterobacter cloacae in burn infection].

In view of a high positive isolation rate and resistance to antibiotics of Enterobacter cloacae in our department, 32 strains of E. cloacae, which were isolated from blood and infected wounds of burned patients from June through November 1990, were randomly selected to determine their susceptibility to 21 antibiotics and their plasmid patterns. It was found that 29 of 32 strains were resistant to at least nine antibiotics, while the other three strains were relatively sensitive. 27 of 32 strains of E. cloacae were tested for plasmid, and among them, three strains (relatively sensitive to antibiotics) contained no plasmid. The plasmid patterns of the other 24 isolates varied with strains, but all of them had a 80 kb plasmid. The 80 kb plasmid was obviously related to the high isolation rate and high resistance to antibiotics of E. cloacae isolated in our department.

Burns↗
PubMed1995

[Electrophoretic analysis of the protein patterns of the nuclear transplant rabbit embryos].

The qualitative patterns of protein synthesis in nuclear transplant rabbit embryos were examined by SDS-polyacrylamide gel electrophoresis followed by silver staining. The results indicated that the qualitative pattern of several protein synthesis in NT embryos was very different from the protein pattern of donor morulae or recipient oocytes, and also not as the same as the protein pattern obtained from fertilized ova at pronuclear formation stage. After fertilization or nuclear transfer, several maternal proteins were no longer synthesized or decreased in the embryo, and some new bands were observed and several protein synthesis were increased obviously. The most intriguing aspect of this study was the observation that all major changes in the protein pattern took place after fertilization or nuclear transfer and were rather similar. It is suggested that the gene activities of the donor nucleus from rabbit morulae are reprogrammed by the oocyte cytoplasm in current nuclear transfer technology, but the reprogramming is incomplete. This paper stresses on the paternal effect during fertilization on gene expression in nuclear transplant rabbit embryos.

Animals↗
PubMed1995

[High efficiency expression of IL-4 using modified cDNA expression vector in mammalian cells].

In order to express eukaryotic gene in eukaryotic cells, a cDNA library was constructed and screened with synthesized probe of IL-4 cDNA. The obtained cDNA fragment 739 bp in length was inserted into pi H3M plasmid and expressed (8 x 10(3) IU/ml) in COS cells. A pdB-HhIL-4 expression plasmid was constructed using pdKCR and pdBPV-1 plasmid and transfected into mouse C127 cells by calcium phosphate coprecipitation. Transfected cells exhibited altered cell morphology, could be continuously cultured in DMEM essential medium and secreted IL-4 lymphokine into 1% FCS condition culture medium. High biological activity (2 x 10(4)/ml) from the culture supernatant was obtained by FACS analysis of Fc epsilon receptor expression on B cell surface.

Animals↗
PubMed1995

[Ultrastructural observation of tendonization of artificial tendon 109HH in rabbit].

Ten New Zealand rabbits were divided into 5 groups at random. Calcaneal tendons were cut bilaterally, then atificial tendon 109HH was used to connect the two ends of the cut tendon. Ultrastructural changes of control group and experimental groups at 2, 6, 12, 28 weeks after section were observed. The results showed that fibroblast proliferated and a lot of ribosome and RER appeared in plasm during 2 approximately 6 weeks, indicating artificial tendon caused fibroblast proliferation. During this period, fibroblast over synthesized collagenous protein and the synthesis of collagenous fibers peaked. During 12-28 weeks, the number of fibroblasts and the synthesis of collagenous protein decreased. Finally, fibroblasts became inactive tendon cells. With the formation of new tendons, the artificial tendens were degradated and absorbed, and disappeared after 12 weeks. The new tendon fibers became thicker and had the correct direction through reconstruction. The structure and function of new tendons could be restored to be consistent with normal values.

Animals↗
PubMed1995

[Analysis of beta-thalassemia mutations and prenated diagnosis in Chengdu population].

Ninety-five of non-differential diagnostic patients were detected by dot-blot analysis on enzymatically amplified DNA with a number of allele specific oligonucleotide probes complementary to the most common mutations in Chengdu population. Prenatal diagnosis was accomplished by the same procedure on enzymatically amplified amniocyte DNA. The result revealed fifty-eight cases of beta-thalassemia. Of the 73 chromosomes tested, twenty-eight (38.4%) had the codon 17(A-->T) mutation, twenty-one (28.8%) had the codon 41-42(-TTCT) mutation, fourteen (19.0%) had the IVS-I-654(C-->T) mutation; nt--28(A-->G) and nt--29(A-->G) mutations were six (8.2%) and four (5.5%) respectively.

Base Sequence↗
PubMed1995

Characteristics of reversal optic cupping in adults glaucoma after reduction of intraocular pressure.

PURPOSE: According to Quigley's hypothesis the dense of connective tissue is the least and the pores of the lamina cribrosa are the largest at the superior and inferior poles of the lamina cribrosa, therefore they are the most vulnerable location to be involved in the characteristic glaucomatous optic nerve damage. To get clinical evidence for the hypothesis, the reversal of optic cup in adults glaucoma after reduction of intraocular pressure (IOP) was examined. METHODS: The stereoscopic flicker comparison on with computerized image system was used to monitor the optic cup's changing, 2 serial superposed stereo pairs were displayed alternatively and rapidly and the changing parts appeared moving Under the stereoscopic observation, the changes of 3-dimension optic cup could be seen and the false positive phenomena caused by photographic angle variation, vascular pulsation could be differentiated from the characteristic change of the cup. Stereo fundus photographs were taken from 31 eyes with hypertension glaucoma before and after treatment of reduction of IOPs which was either diamox administration or trabeculectomy. RESULTS: The result showed that the reversal of optic cups after reduction of IOPs were mostly asymmetrical, especially at the inferior and/or superior poles. By multiple stepwise regression, it is known that the amount of the change is only correlated with the initial elevated IOP. CONCLUSIONS: The study indicated that it was the distortion and deformity of the lamina cribrosa leading to shearing stress that results in glaucomatous characteristic damage in structure and function. The individual tolerance of the lamina cribrosa to the high intraocular pressure and the locations of individual vulnerable at the optic nerve head are various.

Adolescent↗
PubMed1995

[The analysis of orthodontic force for distal movement of maxillary canine].

In this study, the finite element method combining with CAD technique was used to establish the three-dimensional mathematical model of the right maxillary canine and its periodontical tissue. We imitated the different kinds of force which were used during the orthodontic treatment, and analyzed the ways of the teeth moving and the initial stress on the teeth and periodontal tissue. Results showed that is was best to exert couple M and force P simultaneously, especially when M/P = 10 approximately 13 mm, the teeth could be moved fast and wholely without pathological destruction on the periodontical tissue. The results of this study provide some theoretical and experimental basis for clinical practice.

Biomechanical Phenomena↗
PubMed1995

Procoagulant albumin increases vascular endothelial cell prostacyclin secretion.

Vascular endothelium regulates multiple aspects of platelet function through secretion of a variety of substances, including von Willebrand factor, nitric oxide, and prostacyclin (PGI2). The objective of this study was to determine whether procoagulant albumin (P-A1), a modified form of albumin present in normal human plasma could modulate endothelial cell secretion of these substances. P-A1 did not affect constitutive secretion of von Willebrand factor or nitric oxide, but did increase PGI2 secretion in a time- and concentration-dependent manner. Pre-treatment of endothelial cells with aspirin, or use of suramin, a broad-specificity inhibitor, prevented the response to P-A1. Prostaglandin H synthase-2 contributed to the P-A1-induced PGI2 secretion. These results indicate that in addition to inducing tissue factor activity and reducing protein C activation and fibrinolysis, P-A1 also modulates vascular endothelial cell PGI2 secretion, and potentially, platelet function.

Aspirin↗
PubMed1994

Determination of extracellular glutathione in rat brain by microdialysis and high-performance liquid chromatography with fluorescence detection.

A method for the continuous monitoring of extracellular glutathione (GSH) concentrations in rat brain has been developed. This method involved the in vivo sampling of brain extracellular fluid by microdialysis perfusion and the subsequent analysis by high-performance liquid chromatography (HPLC) with fluorescence detection. Perfusates from the microdialysis probes were directly derivatized with methanolic monobromobimane which acted as the fluorescence tag. Separation of the derivatized perfusate was achieved on narrow-bore reversed-phase C18 columns. Recoveries of GSH from the microdialysis probes ranged from 1.5% to 4%. The basal extracellular GSH concentration in rat (Sprague-Dawley) brain cortex was found to be 2.10 +/- 1.78 microM (mean +/- S.D.) (results of 18 rats). Fluorescence detection and separation on narrow-bore columns provided adequate sensitivity for accurate determination of brain extracellular GSH concentrations in rats. With this method, the extracellular GSH concentrations in the cerebral cortex were found to be significantly elevated upon the onset of cerebral ischemia induced by the ligation of bilateral common carotid arteries.

Animals↗
PubMed1994

5-Fluoro-2'-deoxycytidine 5'-monophosphate is a mechanism-based inhibitor of thymidylate synthase.

Thymidylate synthase (TS) is inhibited by 5-fluoro-2'-deoxycytidine 5'-monophosphate (FdCMP). From initial velocity measurements, the apparent Ki for the binary FdCMP-enzyme complex was about 20 microM. In the presence of 5,10-methylene-5,6,7,8-tetrahydrofolate (CH2H4folate), FdCMP causes a time-dependent inactivation of the enzyme and formation of a TS-FdCMP-CH2H4 folate complex. The ternary complex contains one mol of inhibitor per monomer of enzyme, and can be readily isolated on nitrocellulose filters. Dissociation of the ternary complex is quite slow (t1/2 approximately 16 h), and yields unchanged FdCMP. As with the corresponding complex formed with 5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP), the TS-FdCMP-CH2H4 folate complex shows a differential absorbance maximum at 326 nm, and is stable to SDS-PAGE. Taken together, these results indicated that FdCMP is a slow, tight binding inhibitor of TS and has a mechanism of inhibition similar to that of FdUMP.

Cytidine Monophosphate↗
PubMed1994

Resolution of proteins on a phenyl-Superose HR5/5 column and its application to examining the conformation homogeneity of refolded recombinant staphylococcal nuclease.

In order to examine the effect of amino acid substitutions on protein retention in hydrophobic interaction chromatography and the resolution of a phenyl-Superose HR5/5 column, two groups of staphylococcal nucleases, named Y113/W140 (wild-type), Y113W/W140 and Y113/W140F, Y113W/W140F, were produced by substituting tryptophan (W) for tyrosine (Y) at residue 113 and phenylalanine (F) for tryptophan (W) at residue 140. For each group, the proteins have the same amino acid at residue 140, but a different amino acid at residue 113. The solvent perturbation of nuclease fluorescence and 1,8-anilinoaphthalene-8-sulfonate binding studies showed that the substitutions do not change the side-chain positions of amino acids at residues 113 and 140. Chromatography of the proteins on the Phenyl-Superose HR5/5 column showed that the proteins with tryptophan at residue 113 have longer retention times than the proteins having tyrosine at residue 113; the proteins with the same amino acid at residue 113 have almost the same retention time regardless of substituting phenylalanine for tryptophan at residue 140. The studies clearly indicate that not all amino acid substitutions have an effect on protein retention; the contribution to retention of a given amino acid substitution depends on its position in a protein. Single amino acid substitutions at the exterior surface of a protein, which change the strength of hydrophobic interaction, can affect the protein retention in hydrophobic interaction chromatography. Staphylococcal nuclease and its mutants with only one amino acid difference on their surfaces can be discriminated by the phenyl-Superose column.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗