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Biomedical subjects

L Gao

Publications and source records attributed to L Gao.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Residue of sodium hyaluronate in aqueous humor following intraocular lens implantation].

OBJECTIVE: To determine the residue of sodium hyaluronate in aqueous humor following intraocular lens (IOL) implantation. METHODS: The percentage concentration of sodium hyaluronate in aqueous humor in 23 patients (25 eyes) having undergone IOL implantation was measured by Shimadzu UV-3101 ultraviolet spectrophotometer before and after irrigation with BSS 2 ml, 5 ml and 8 ml. RESULTS: The different percentage concentrations of sodium hyaluronate were 65.50% +/- 18.12%, 10.20% +/- 4.80%, 2.19% +/- 1.83% and 0.70% +/- 0.91%. CONCLUSION: Replacement of aqueous humor by BSS 2 ml can eliminate the most part of sodium hyaluronate. Replacement of aqueous humor by BSS 8 ml can decrease the residue of sodium hyaluronate to trace amount and the postoperative intraocular pressure can maintain in normal range.

Aqueous Humor↗
PubMed1998

[Determination of diflunisal in plasma by RP-HPLC after solid-liquid extraction].

A RP-HPLC method was developed with solid-liquid extraction technique. Plasma sample was extracted on a macroreticular resin cartridge with methanol--glacial acetic acid (99:1) as elution solvent. After extraction, the assay was carried out on a Spherisorb C18 column with p-phenylphenol as internal standard. The mobile phase is a mixture of methanol--water--glacial acetic acid (66:30:4). UV detection was performed at 250 nm. The flow rate was 1.0 ml.min-1. A good linearity was found at the concentration range from 0.5 to 100 micrograms.ml-1, with the lowest detection limit 0.02 microgram.ml-1 (S/N = 2). The extraction and method recoveries were 91.65% and 97.25% respectively, while the RSD for the within-day and between-day precision were all less than 10%. The above method was applied to determine the plasma concentration of difunisal in three human volunteers after a single oral dosage of 300 mg. Two hours after administration, the plasma concentration of diflunisal reached maximum level. A two compartment method was used to study the pharmacokinetic parameters. The T1/2 alpha and T1/2 beta were 1.40 h and 17.85 h, respectively.

Chromatography, High Pressure Liquid↗
PubMed1998

[Study on a new type of endoscope based on micro motor].

The application of Micro Electro Mechanical System (MEMS) on the fields of biomedical engineering is a newly technological field. Applying a micro motor, whose diameter is only 2 mm, as driving device of this system, this paper presented a new type of medical endoscope whose front tip of diagnosing tube could work automatically.

Endoscopes↗
PubMed1998

[The effects of jianpizengmian granule on tumor growth and immune function].

The effects of Jianpizengmian (JPZM) granule on tumor growth and immune function were researched in tumor-bearing mice. The results showed it had significant inhibiting activity against S180 and HePA by oral JPZM. The inhibitory rate of JPZM reached 46.25% and 45.57%. JPZM could markedly increase the index of spleen and thymus, the level of serum hemolysin and the spleen lymphocytes transformation in tumor-bearing mice, compared to control group (H2O) respectively.

Animals↗
PubMed1997

Human genes encoding U3 snRNA associate with coiled bodies in interphase cells and are clustered on chromosome 17p11.2 in a complex inverted repeat structure.

Coiled bodies (CBs) are nuclear organelles whose morphological structure and molecular composition have been conserved from plants to animals. Furthermore, CBs are often found to co-localize with specific DNA loci in both mammalian somatic nuclei and amphibian oocytes. Much as rDNA sequences are called nucleolus organizers, we term these coiled body-associated sequences 'coiled body organizers' (CBORs). The only sequences that have been shown to be CBORs in human cells are the U1, U2 and histone gene loci. We wanted to determine whether other snRNA genes might also act as CBORs. In this paper we show that human U3 genes (the RNU3 locus) preferentially associate with CBs in interphase cells. In addition, we have analyzed the genomic organization of the RNU3 locus by constructing a BAC and P1 clone contig. We found that, unlike the RNU1 and RNU2 loci, U3 genes are not tandemly repeated. Rather, U3 genes are clustered on human chromosome 17p11.2, with evidence for large inverted duplications within the cluster. Thus all of the CBORs identified to date are composed of either tandemly repeated or tightly clustered genes. The evolutionary and cell biological consequences of this type of organization are discussed.

Base Sequence↗
PubMed1997

Immunosuppression by D-isomers of HLA class I heavy chain (amino acid 75 to 84)-derived peptides is independent of binding to HSC70.

BACKGROUND: Peptides derived from the class I heavy chain were shown to modulate immune responses in vitro and in vivo. A peptide derived from HLA-B2702 (2702.75-84) inhibited differentiation of cytotoxic T cells as well as T cell and natural killer cell-mediated cytotoxicity in vitro. Peptide-mediated immunomodulation seemed to be independent of the MHC proteins expressed by responder and stimulator cells. In vivo studies in rodents demonstrated prolongation of heart and skin allograft survival after peptide therapy. Here, the correlation between the peptide's biological activity and its amino acid sequence was analyzed using peptides derived from amino acid 75-84 of several mouse, rat, and human MHC class I proteins as well as peptides with single amino acid substitutions in the 2702.75-84 sequence. METHODS: Peptides consisting of both L- and D-amino acids were tested for inhibition of murine and human T cell-mediated and lymphokine-activated killer cell-mediated cytotoxicity, binding to hsc70, and prolongation of heart allograft survival in vivo. RESULTS: Replacement of glutamic acid residue (E) at position 75 with valine (V) resulted in a peptide [2702.75-84(E>V)] with increased in vitro and in vivo activity but unchanged affinity for hsc70. Surprisingly, both L- and D-isomers of 2702.75-84 and 2702.75-84(E>V) inhibited cytotoxic cells in vitro and prolonged heart allograft survival in vivo. However, as expected, the peptides consisting of D-amino acids did not bind to hsc70. CONCLUSION: Assuming that both D- and L-isomers modulate immune responses by similar mechanisms, these results suggest that the peptides' effect is independent of binding to hsc70.

Adenosine Triphosphatases↗
PubMed1997

Evidence for a role of C-terminal amino acid residues in skeletal muscle Ca2+ release channel (ryanodine receptor) function.

The effects of deleting 1, 3 and 15 amino acid residues from the highly conserved C-terminus of the tetrameric skeletal muscle ryanodine receptor (RyR) complex were determined. Immunoblot analysis indicated similar expression levels in HEK293 cells for full-length and mutant proteins. Full-length and RyR lacking the last amino acid showed [3H]ryanodine binding and single channel activities typical of native receptors. Deletion of 3 amino acids resulted in decreased activities, whereas deletion of 15 amino acids yielded an inactive RyR. These results suggest that the most 15 C-terminal amino acids are important for the expression of a functional RyR complex.

Animals↗
PubMed1997

Cloning of the cDNA coding for rat brain CMP-NeuAc:GD3 alpha2-8 sialyltransferase.

The cDNA coding for GT3-synthase has been cloned from a rat fetal brain cDNA library. The complete nucleotide sequence and the deduced amino acid sequence of the rat GT3-synthase cDNA were highly homologous to those of the mouse GT3-synthase. Quantitative RT-PCR showed that, as a key enzyme for the synthesis of 'c'-series gangliosides, the expression of GT3-synthase was developmentally regulated in embryonic rat brains.

Amino Acid Sequence↗
PubMed1997

Ghost artifact reduction for echo planar imaging using image phase correction.

An algorithm is described for reducing ghost artifacts in echo planar imaging (EPI) using phase corrections derived from images reconstructed using only even or odd k-space lines. The N/2 ghost, that arises principally from time-reversal of alternate k-space lines, was significantly reduced by this algorithm without the need for a calibration scan. In images obtained in eight subjects undergoing EPI for auditory functional MRI (fMRI) experiments, N/2 ghost intensity was reduced from 10.3% +/- 2.1% (range: 7.9-14.1%) to 4.5% +/- 0.2% (range: 4.1-4.9%) of parent image intensity, corresponding to a percent reduction in ghost intensity of 54% +/- 9% (range: 43-65%), and the algorithm restored this intensity to the parent image. It provided a significant improvement in image appearance, and increased the correlation coefficients related to neural activation in functional MRI studies. The algorithm provided reduction of artifacts from all polynomial orders of spatial phase errors in both spatial directions. The algorithm did not eliminate N/2 ghost intensity contributed by field inhomogeneities, susceptibility, or chemical shift.

Algorithms↗
PubMed1997

Mucosal immunization with DNA-liposome complexes.

The mucosal surfaces represent the primary site for transmission of several viruses including HIV. To prevent mucosal transmission and dissemination to the regional lymph nodes, an effective HIV vaccine may need to stimulate immune responses at the genital and rectal mucosa. Optimal induction of mucosal immunity in general requires targeting antigens to the specialized antigen presenting cells of mucosal associated lymphoid tissues. The nasal mucosa may provide a simple, non-invasive route to deliver DNA encoding the introduced gene to stimulate mucosal immunity. As a first step to evaluate the feasibility of this approach, we have investigated as a model system, systemic and mucosal immune responses elicited to firefly luciferase generated by DNA immunization. Incorporating DNA into liposomes with cationic lipids enhanced luciferase expression in nasal tissue, and was associated with induction of a humoral response in serum and vaginal fluids and also a proliferative and cytotoxic T lymphocyte response in the spleen and iliac lymph nodes draining the genital and rectal mucosa.

AIDS Vaccines↗
PubMed1997

Effects of second-hand smoke and gender on infarct size of young rats exposed in utero and in the neonatal to adolescent period.

OBJECTIVES: We sought to assess the effects of second-hand smoke (SHS) and gender on infarct size in young rats exposed in utero or in the neonatal to adolescent period, or both. BACKGROUND: We previously demonstrated that exposure to SHS increases infarct size in a rat model of ischemia and reperfusion, with a dose-response relation. These results are consistent with epidemiologic studies demonstrating that SHS increases risk of death from heart disease. METHODS: Thirty-one pregnant female rats were randomly divided into two groups: those exposed to SHS and a control group (non-SHS). After 3 weeks, each rat had given birth to 10 to 12 rats. One hundred one neonatal rats were divided into four groups according to exposure to SHS in utero (SHSu) and randomized to SHS exposure in the neonatal to adolescent period (SHSna). After 12 weeks, all rats were subjected to 17 min of left coronary artery occlusion and 2 h of reperfusion. RESULTS: Birth mortality was higher in the SHSu group than in the non-SHSu group (11.9% vs. 2.8%, p < 0.001). Body weight of neonatal rats at 3 and 4 weeks in the two SHSu groups was lower than that of rats in the two non-SHSu groups (p < 0.001). Exposure to SHSna increased endothelin-1 levels in plasma (p = 0.001). In all 70 young rats who survived the neonatal period, infarct size (Infarct mass/Risk area x 100%) was greater in the SHSna groups than in the non-SHSna groups (p = 0.005) and in the male groups than in the female groups (p < 0.001). CONCLUSIONS: Exposure to SHS in the neonatal to adolescent period and male gender increased myocardial infarct size in a young rat model of ischemia and reperfusion. These results are consistent with epidemiologic studies demonstrating that SHS increases the health risk to neonates and adolescents.

Angiotensin II↗
PubMed1997

Monoclonal antibody to the HLA class I alpha 3 domain inhibits T cell activation and prolongs cardiac allograft survival in HLA-transgenic mice.

Antibodies recognizing MHC class I molecules expressed on the surface of T cells have been shown to inhibit T cell responses in vitro. These findings suggested that therapy with such an antibody may prevent rejection and promote graft acceptance. We therefore tested the effect of an anti-HLA class I alpha 3 domain antibody (TP25.99) in vivo using transgenic C57BL/6 mice expressing HLA-B2705. Flow cytometric analysis confirmed the binding of TP25.99 to normal human peripheral blood lymphocytes and to mouse spleen cells, bone marrow cells and thymocytes isolated from hemizygous (+/-) transgenic littermates but not from homozygous (-/-) littermates. TP25.99 inhibited OKT-3-induced, but not PMA+ionomycin-induced, proliferation of human peripheral blood lymphocyte as well as anti-CD3 or Con A-induced proliferation of HLA+ mouse T cells. Both intact monoclonal antibody TP25.99 and TP25.99 Fab inhibited T cell proliferation. Reduced proliferation was associated with suppressed production of interleukin-2 as measured by ELISA. The efficacy of TP25.99 Fab in vivo was evaluated in a heart allograft model. Antibody therapy of (H-2h, B2705+) transgenic recipients of allogeneic Balb/c (H-2d) heart grafts prolonged graft survival significantly (MST = 19.8 +/- 6.4, p = 0.003) compared to treated (H-2b, B2705-) (MST = 9.17 +/- 2.2) or untreated (H-2b, B2705+) (MST = 10.0 +/- 2.8) transgenic recipients. This demonstrates that immunomodulation through anti-HLA class I antibody therapy can lead to prolongation of graft survival.

Animals↗
PubMed1997

Ca(2+)-dependent p47phox translocation in hydroperoxide modulation of the alveolar macrophage respiratory burst.

Oxidative stress produces dual effects on the respiratory burst of rat alveolar macrophages. Preincubation with hydroperoxide concentrations [H2O2 or tert-butyl hydroperoxide (t-BOOH); < 50 microM] enhances stimulation of the respiratory burst, whereas higher concentrations inhibit stimulation. Both the enhancement and inhibition are markedly attenuated by buffering t-BOOH-induced changes in intracellular Ca2+ concentration ([Ca2+]i). Phosphorylation of the NADPH oxidase component p47phox and its translocation from cytoplasm to plasma membrane are essential in respiratory burst activation. Phorbol 12-myristate 13-acetate (PMA)-stimulated p47phox phosphorylation was negligibly affected by 25 or 100 microM t-BOOH. Nonetheless, 25 microM t-BOOH increased PMA-stimulated p47phox translocation, whereas 100 microM t-BOOH decreased PMA-stimulated translocation. In unstimulated cells, however, neither phosphorylation nor translocation of p47phox was affected by t-BOOH. Buffering of the t-BOOH-mediated changes of [Ca2+]i abolished the effects of t-BOOH on PMA-stimulated translocation in parallel to effects upon the respiratory burst. The results suggest that the dual effects of hydroperoxides are mediated, in part, by Ca(2+)-dependent processes affecting the assembly of the respiratory burst oxidase at steps that are separate from p47phox phosphorylation.

Animals↗