Biomedical subjects

Li Shi

Publications and source records attributed to Li Shi.

44 records · Page 3Linked to original sources

PubMed2003

[Effects of infrasound on visual electrophysiology in mice].

OBJECTIVE: To investigate the possible effects of infrasound on visual functions. METHOD: One hundred and fifty mature male Kunming-mice were divided into 5 groups, in which one was control and the other four were exposed to infrasound of 8 Hz, 90 dB; 8 Hz, 130 dB; 16 Hz, 90 dB and 16 Hz, 130 dB 2 h/d respectively. The exposure time for them were 0, 1, 4, 7, 14 and 21 d respectively, each group was divided into 6 sub-groups. Electroretinogram (ERG), oscillatory potentials (OPs), and visual evoked potential (VEP) were recorded after exposure. RESULT: The visual electrophysiological indices after 8 Hz, 90 dB and 16 Hz, 90 dB exposures were similar except for a little difference at some temporal points (P<0.05). Most of the indices in 8 Hz, 130 dB group changed after 7 d exposure, and the longer the exposure, the more obvious changes were observed (P<0.01). The indices in 16 Hz, 130 dB group changed obviously after 1 d and reversed with increase of exposure time (P<0.01). CONCLUSION: The effect of infrasound on visual functions are related to its frequency and intensity. Infrasound of different frequencies causes different levels of retinal resonance, which leads to different degrees of cellular lesion and produces different electrical potentials.

Acoustic Stimulation↗

PubMed2003

Experimental murine cryptococcal infection results in contamination of bedding with Cryptococcus neoformans.

Cryptococcus neoformans is a fungal pathogen that survives in diverse environments. To determine whether cages of mice infected with C. neoformans posed an infection risk to animal caregivers, we investigated whether the fungus could be isolated from the bedding or stool of mice infected by intratracheal (i.t.), intravenous (i.v.), or intraperitoneal (i.p.) routes. The bedding of mice infected i.t. was contaminated with C. neoformans. In contrast, no contamination of bedding with C. neoformans was detected in cages of mice infected i.v. or i.p. C. neoformans was not isolated from murine feces. The C. neoformans strain recovered from bedding material was indistinguishable from the infecting strain by biochemical and molecular techniques. This result suggests that precautions may be warranted when disposing bedding from cages that housed mice with pulmonary C. neoformans infection.

Animals↗

PubMed2003

[Expression of neuron-specific enolase and olfactory marker protein in the developing olfactory mucosa of human fetuses].

OBJECTIVE: To study the expression of neuron-specific enolase (NSE) and olfactory marker protein (OMP) in the developing olfactory mucosa of human fetuses. METHOD: The expression of NSE and OMP in the olfactory mucosa of 6 human fetuses (12, 16, 20, 24, 28 and 34 weeks) was studied using the technique of immunohistochemistry. RESULTS: NSE immunological positive reactions were seen in all 6 fetal mucosa from gestational 12 (G12) to G34, with plenty of positive-stained dual-pole neuron cells. At G12, the positive cells aligned tightly, the cell bodies were localized in the lower portion of olfactory epithelium and the positive-stained area occupied upper 2/3 of fetal nasal mucosa. With the development, the positive cells gradually became multilayer, but the density and the relative area of positive-cells reduced. At G34, the positive cells were located only in upper 1/3 of nasal mucosa. OMP-positive reactions were localized in a few dual-pole neurons at G12, the number was much less than NSE-positive cells in the same fetus. With the development, the OMP-positive cells gradually increased with most of the cell bodies located in the upper portion of epithelium, but number still relatively less than the NSE-positive cells at the same age. CONCLUSION: At G12, there were lots of olfactory neuron in the olfactory mucosa and only a few olfactory neurons had became mature. With the development, the olfactory epithelial area reduced but the number of mature olfactory neurons increased. At the last trimester, fetal olfactory sensor was almost matured.

Female↗

PubMed2003

[Cytoxic T lymphocyte responses to hepatitis B virus small surface antigen in BALB/c mice].

OBJECTIVE: To observe cytotoxic T lymphocytes (CTL) responses induced by immunization of mice with hepatis B small surface antigen (S-HBsAg). METHODS: BALB/c(H-2d) mice were injected intraperitoneally with S-HBsAg at the doses ranging from 0-5 microg with a booster injection 2 weeks later. Four weeks after the booster immunization, the specific cytotoxic reactivity of the spleen lymphocytes isolated from the immunized mice, following stimulation by S-HBsAg specific CTL epitope peptide in vitro, with 51Cr-labeled P815 cells treated with the peptide was observed. RESULTS: The percentage of specific release of 51Cr in mice immunized with S-HBsAg at the doses of 0, 0.65, 1.25, 2.5, and 5 microg was 31.21%+/-9.23%, 42.36%+/-19.32%, 91.21%+/-22.97%, 69.25%+/-24.13% and 51.49%+/-21.661% respectively. In mice receiving the only primary vaccination, the corresponding percentage was 27.34%+/-14.25%, 32.27%+/-15.35%, 56.28%+/-24.35%, 44.34%+/-18.65% and 40.76+/-56% respectively. CONCLUSION: Immunization with S-HBsAg efficiently elicits CTL response in BALB/c mice in a dose-dependent manner and enhanced by booster immunization.

Animals↗

PubMed2002

[Protective and rescue effects of transgenic bFGF/GFP expression mediated by cationic liposome on gentamicin-induced guinea pig cochlear toxicity].

OBJECTIVE: To observe the expression of cationic stearylamine (SA) liposome mediated basic fibroblast growth factor/green fluorescence protein (bFGF/GFP) gene in the cochlea of guinea pig, and evaluate the protection and rescue action of bFGF against the damage caused by gentamicin. METHODS: Thirty-six guinea pigs were divided into 3 experimental groups. Prevention group with inoculation of SA-bFGF/GFP complexes through the round window of right ear and injection of gentamicin 150 mg.kg(-1).d(-1) one day after for 8 days and rescue group with injection of gentamicin for 8 days and infusion of SA-bFGF/GFP complexes in the same way on the ninth day, and control group with only injection of gentamicin for 8 days. Auditory brainstem responses (ABR) was measured prior to and after the administration and before the animals were killed respectively. The animals were killed after the experiment and ABR test, and specimens and slices of chochleae were made to examine the absence of outer and inner hair cells. The expression of GFP in cochlea shown by green fluorescence was observed with fluorescent microscopy. RESULTS: Fluorescent microscopy showed green fluorescence in the cochleae of guinea pigs in prevention and rescue groups. There was no significant difference in ABR threshold between the left and right ears of animals in each group before and after experiment, among both ears of animals in the 3 groups before experiment, and between prevention and rescue group groups before killing (all P > 0.05). However, the ABR thresholds in prevention group and rescue group were significantly lower than that in control group before the animals were killed (P < 0.01 and P < 0.05). The average number of lost outer hair cells was 5 106 +/- 299 cells and 5 605 +/- 109 cells in prevention group and rescue group respectively, without a significant difference between them (P > 0.05). The average amount of missing inner hair cells was 301 +/- 64 cells and 487 +/- 92 cells in prevention group and rescue group respectively, without a significant difference between them (P > 0.05), and significantly lower than that in control group (1 062 +/- 67, P < 0.01 and P < 0.05). The average amount of missing outer hair cells in control group was 6 248 +/- 119 cells, significantly higher than that in prevention group (5 106 +/- 299, P < 0.01) and that in rescue group (5 605 +/- 109, P < 0.05). CONCLUSION: SA-liposome mediated bFGF/GFP gene, which was perfused in one ear, can be expressed highly in both cochleae of the guinea pig, and may protect and rescue cochlea against gentamicin ototoxicity.

Amines↗

PubMed2002

Pharmaceutical and immunological evaluation of a single-shot hepatitis B vaccine formulated with PLGA microspheres.

A single-shot Hepatitis B vaccine formulation using poly(d,l)-lactide-co-glycolide acid (PLGA) microspheres as a delivery system was examined using a variety of biophysical and biochemical techniques as well as immunological evaluation in C3H mice. PLGA microsphere encapsulation of the Hepatitis B surface antigen (HBsAg), a lipoprotein particle, resulted in good recoveries of protein mass, protein particle conformational integrity, and in vitro antigenicity. Some partial delipidation of the HBsAg, however, was observed. The loading and encapsulation efficiency of HBsAg into the PLGA microspheres were measured along with the morphology and size distribution of the vaccine-loaded PLGA microspheres. The in vitro release kinetics of HBsAg from the PLGA microspheres was evaluated and found to be affected by experimental conditions such as stirring rate. HBsAg showed enhanced storage stability at 37 degrees C in the slightly acidic pH range reported to be found inside PLGA microspheres; thus, the antigen is relatively stable under conditions of temperature and pH that may mimic in vivo conditions. The immunogenicity of the microsphere formulations of HBsAg was compared with conventional aluminum adjuvant formulated HBsAg vaccine in C3H mice. Comparisons were made between aluminum formulations (one and two injections), PLGA microsphere formulations (single injection), and a mixture of aluminum and PLGA microsphere formulations (single injection). The nine-month serum antibody titers indicate that a single injection of a mixture of aluminum and PLGA-formulated HBsAg results in equal or better immune responses than two injections of aluminum-formulated HBsAg vaccine. Based on these in vitro and in vivo studies, it is concluded that HBsAg can be successfully encapsulated and recovered from the PLGA microspheres and a mixture of aluminum-adjuvanted and PLGA-formulated HBsAg can auto-boost an immune response in manner comparable to multiple injections of an aluminum-formulated vaccine.

Animals↗

PubMed2002

The expression of VacA in BCF of Helicobacter pylori and its relationship to vacuolated effect.

The vacuolated effect of Helicobacter (H. pylori) and its relationship to vacuolated cytotoxin antigen (VacA) were investigated by the method of cytotoxic test and SDS-pobyacrylamide gel electrophoresis (SDS-PAGE). Of the 62 clinical isolates, the broth culture filter (BCF) of 43 strains caused the Vero cell intracytoplasmically vacuolated. H. pylori strains were divided into H. pylori (Toxin+) group with vacuolated effect and H. pylori (Toxin-) group without vacuolated effect. The analysis of the BCF of H. pylori (Toxin+) and that of H. pylori (Toxin-) was studied by SDS-PAGE and Scan reader. A kind of protein with 87 ku molecular weight was recognized in the BCF of 30.23% (13/43) H. pylori (Toxin+) strains but in none of that of H. pylori (Toxin-) strains, the difference was statistically significant (P < 0.05). There was a significant and concordant relationship between OD of the protein band with 87 ku molecular weight and titer of vacuolated activity of H. pylori (Toxin+) (r = 0.67 and P < 0.05 by linear regression analysis). H. pylori strains were divided into H. pylori (Toxin+) group with vacuolated effect and H. pylori (Toxin-) group without vacuolated effect. The vacuolated effect of H. pylori (Toxin+) was caused by the protein with 87 ku molecular weight (VacA).

Adolescent↗

PubMed2002

Sequence analysis and molecular characterization of a nitrocatechol dioxygenase gene from Pseudomonas putida.

A Pseudomonas putida capable of degrading polychlorinated biphenyl was also found to transform 4-nitrocatechol to 3-nitro-2-hydroxy-6-oxohexa-2,4-dienoic acid (NHODA). Crude cell extract of this bacterium exhibited an enzyme (nitrocatechol dioxygenase, Ndo) activity catalyzing this transformation. The gene encoding Ndo was cloned in E. coli. The cloned gene (ndo) expressed in E. coli had enzyme activity that degraded not only 4-nitrocatechol but also 4-chlorocatechol, 4-methylcatechol, 2,3-dihydroxybiphenyl, and 4'-chloro-2,3-dihydroxybiphenyl. Nucleotide sequence analysis of the cloned ndo exhibited an open reading frame of 939 base pairs. This sequence can encode a 313 amino acids protein of approximately molecular weight of 35 kd, which was confirmed by in vitro transcription and translation assay and SDS-PAGE analysis. A putative ribosomal binding site (GAGGAGA) was present 7 base pairs upstream from the AUG start codon and a promotor site homologous to E. coli '-10' and '-35' regulatory region was located at '-123' and '-174' area of our clone with sequences of TTGAAG and GTGACA, respectively. The deduced amino acid sequence showed 69% homology with Cdo from Burkholderia cepacia AAI. A unique insertion of 21 amino acids was found towards the N-terminal of the Ndo. Expression of ndo in strain OU83 was repressed in presence of 3-chlorobenzoic acid as judged by the decrease in the expression of ndo specific transcript.

Amino Acid Sequence↗