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Biomedical subjects

J Sun

Publications and source records attributed to J Sun.

At least 667 records · Page 37Linked to original sources
PubMed1993

Predominance of CD8+ T lymphocytes in the inflammatory lesions of mice with acute Trypanosoma cruzi infection.

Using glycol methacrylate in conjunction with avidin-biotin-peroxidase complex techniques, we studied the contribution of T cell subsets to tissue inflammation during acute Trypanosoma cruzi infection. Two mouse/parasite model systems whose parasitology and pathology behaved differently were used. In C57Bl/6J mice infected with the T. cruzi Brazil strain, the levels of parasitism in blood and tissue (myocardial and skeletal muscle) reached a maximum at week 6 and decreased rapidly thereafter. Inflammatory responses in tissue corresponded with the parasitism, but decreased in intensity more gradually than that of parasitism. The T lymphocytes (Thy 1.2+) were found to be the major lymphocyte population in inflammatory cardiac and skeletal muscles (64.6-81.2%) at both three and six weeks postinfection. Among T cells, CD8+ cells (47.0-58.9%) significantly outnumbered CD4+ cells (9.3-18.6%). The number of B cells (0-1.0%) and macrophages was low. Experiments using C3H/HeSnJ mice infected with the Sylvio X10/4 clone of T. cruzi at 30 days postinfection resulted in similar findings except for a higher CD8+:CD4+ ratio. The primary finding of this study is that Thy 1.2+CD8+CD4- T lymphocytes are the major cell population in both heart and skeletal muscle in acute murine T. cruzi infection. The predominance of CD8+ T cells coincident with the decrease in the tissue parasite burden suggests a role for CD8+ T cells in the control of T. cruzi at the level of the infected cell.

Acute Disease↗
PubMed1993

[Observation of clinical effect of bioactive glass titanium alloy core implant]

A novel kind of implant made of titanium alloy spray coated with a suitable bioactive glass was investigated.49 implantation were done in clinical patients from Oct 1988 to 1992.42 implantation functioned well up to the time.7 implantation failed. The success rate is 85.71%.The authors have also discussed the indications,method of implantation and other related things on the paper.

Journal Article↗
PubMed1993

Small subunit ribosomal RNA gene sequence of the oyster parasite Perkinsus marinus.

The small subunit rRNA gene of the oyster pathogen Perkinsus marinus was characterized from cells of infected oyster hemolymph by polymerase chain reaction and molecular cloning. The gene, 1,793 nucleotides in size, has 77.2% sequence similarity to that of its host, the eastern oyster Crassostrea virginica. The sequence was confirmed using recently available in vitro cultures of P. marinus. DNA from pure P. marinus culture was amplified with specific primers synthesized according to the sequence from infected oyster hemolymph, and predicted size fragments were obtained. Furthermore, restriction digests yielded fragments of expected size in amplified rDNA from in vitro cultures. The P. marinus sequence has 97.5% similarity to the Perkinsus sp. sequence from the Australian mollusc Anadara trapezia.

Animals↗
PubMed1993

Effects of prolonged CO2 inhalation on shivering thermogenesis during cold-water immersion.

We investigated the effect of prolonged hypercapnia on human thermoregulation during immersion of seven male subjects in a 15 degrees C water bath until their esophageal temperature dropped to 35 degrees C or until 1 h had elapsed. In the control trial, subjects inspired room air, whereas in the other trial the inhaled gas mixture was a 4% CO2:20% O2:76% N2 gas mixture. Oxygen uptake (VO2, liter.min-1), inspired minute ventilation (VI, liter.min-1), esophageal temperature (Tes, degree C), mean unweighted skin temperature (Tsk, degree C), mean heat flux (Q, W.m-2), and electromyographic (EMG, mV) activity of the trapezius muscle were recorded. VO2 and integrated EMG (IEMG) activity were used as the primary indicators of shivering thermogenesis. There was a tendency for elevated VO2, albeit not significant, in the CO2 trial compared to the air trial. We observed no significant differences in the IEMG between the air and CO2 trials. These results suggest that prolonged inhalation of a gas mixture containing 4% CO2 does not have a significant inhibitory effect on shivering thermogenesis and does not enhance the cooling rate of the body core. The absence of any shivering attenuation is most likely due to the small blood PCO2 increase incurred by inhalation of 4% CO2, compensation of hypercapnic-induced respiratory acidosis, and a strong thermal drive from core and peripheral regions. It is unlikely that elevated PICO2 levels contribute significantly to the etiology of hypothermia in divers.

Adult↗
PubMed1992

Nucleolar and cytoplasmic localization of annexin V.

The subcellular localization of annexin V in cultured human umbilical vein endothelial cells, epithelial cells and fibroblasts was examined. Indirect immunofluorescence and immunoblotting studies using affinity-purified anti-annexin V antibodies revealed that annexin V is located within the cytoplasm and nucleus of these cells. Further examination and direct binding studies showed that annexin V within the nucleus is associated with the nucleolus. These findings suggest that annexin V may play a role in a nucleolar function, such as ribosome assembly and transport.

Annexin A5↗
PubMed1992

The histone mRNA 3' end is required for localization of histone mRNA to polyribosomes.

The final step in mRNA biosynthesis is transport of the mRNA from the nucleus to the cytoplasm. Histone genes from which the 3' stem-loop has been deleted are transcribed to give RNAs with heterogeneous 3' ends. These RNAs are localized in the nucleus and are stable. Addition of the histone 3' processing signal either on short (< 250 nts) or long (> 1000 nts) transcripts restores 3' processing and transport of the mRNA to the cytoplasm. In addition chimeric histone-U1 snRNA genes which produced RNAs with either histone or U1 3' ends were analyzed. Transcripts which ended with U1 snRNA 3' ends were not efficiently localized to polyribosomes. However, transcripts containing the same sequences including the snRNA 3' end followed by the histone 3' end were present in the cytoplasm on polyribosomes. Taken together these results suggest that the histone 3' end is required for export of histone mRNA to the cytoplasm and association of the mRNA with polyribosomes.

Animals↗
PubMed1992

Increased numbers of T cells recognizing multiple myelin basic protein epitopes in multiple sclerosis.

Myelin basic protein (MBP)-autoreactive T cells have a crucial pathogenetic role in experimental allergic encephalomyelitis (EAE) and certain MBP epitopes may be immunodominantly recognized. The heterogeneity and quantity of the T cell response to different epitopes of MBP in multiple sclerosis (MS) and non-MS controls is not so clearly defined. We now study T cell reactivity to six different peptides of MBP in MS compared to controls in short-term cultures of blood mononuclear cells by measuring numbers of T cells that secrete interferon-gamma in response to antigen. In comparison with controls, MS patients showed dramatically increased numbers of MBP peptide-reactive T cells with mean values varying between 10.4 and 22.5 per 10(5) blood mononuclear cells. Among those MBP peptides examined (amino acid 1-20, 63-88, 89-101, 96-118, 110-128 and 148-165), no single peptide is preferentially recognized. Neither is any preferential response apparent after subdivision of the MS patients according to their HLA-DR genotype. Our findings suggest that a quantitative increase of a broad repertoire of myelin-autoreactive T cells with capacity to secrete IFN-gamma can be important for the pathogenesis of MS.

Adult↗
PubMed1992

Amino alcohol modulation of hippocampal acetylcholine release.

The synthesis and release of 3H-acetylcholine was measured in hippocampal slices of adult rat brain following acute in vitro exposure to ethanolamine. Evoked release of 3H-acetylcholine was elevated by 60-70% but 3H-acetylcholine synthesis was unaffected. Other amino alcohols were also found to significantly increase evoked 3H-acetylcholine release. The effect may be stereochemically mediated since only one of four possible propanolamine configurations, R-alaninol, was active. The most potent compound tested was R-prolinol which showed an EC50 nearly 10-fold lower than that of either R-alaninol or ethanolamine; S-prolinol was inactive. Slices taken from adult rats which had been fed active compounds for two weeks also exhibited enhancements in evoked 3H-acetylcholine release. These results indicate that amino alcohols modulate acetylcholine release in the rat hippocampus.

Acetylcholine↗
PubMed1992

Sucrose Synthase in Wild Tomato, Lycopersicon chmielewskii, and Tomato Fruit Sink Strength.

Here it is reported that sucrose synthase can be readily measured in growing wild tomato fruits (Lycopersicon chmielewskii) when suitable methods are adopted during fruit extraction. The enzyme also was present in fruit pericarp tissues, in seeds, and in flowers. To check for novel characteristics, the wild tomato fruit sucrose synthase was purified, by (NH(4))(2)SO(4) fraction and chromatography with DE-32, Sephadex G-200, and PBA-60, to one major band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The following characteristics were obtained: native protein relative molecular weight 380,000; subunit relative molecular weight 89,000; K(m) values with: sucrose 53 millimolar, UDP 18.9 micromolar, UDP-glucose 88 micromolar, fructose 8.4 millimolar; pH optima between 6.2 to 7.3 for sucrose breakdown and 7 to 9 for synthesis; and temperature optima near 50 degrees C. The enzyme exhibited a high affinity and a preference for uridylates. The enzyme showed more sensitivity to divalent cations in the synthesis of sucrose than in its breakdown. Sink strength in tomato fruits also was investigated in regard to sucrose breakdown enzyme activities versus fruit weight gain. Sucrose synthase activity was consistently related to increases in fruit weight (sink strength) in both wild and commercial tomatoes. Acid and neutral invertases were not, because the published invertase activity values were too variable for quantitative analyses regarding the roles of invertases in tomato fruit development. In rapidly growing fruits of both wild and commercially developed tomato plants, the activity of sucrose synthase per growing fruit, i.e. sucrose synthase peak activity X fruit size, was linearly related to final fruit size; and the activity exceeded fruit growth and carbon import rates by at least 10-fold. In mature, nongrowing fruits, sucrose synthase activities approached nil values. Therefore, sucrose synthase can serve as an indicator of sink strength in growing tomato fruits.

Journal Article↗
PubMed1992

[Conditions for dextranase formation by Paecilomyces lilacinus].

Induced formation conditions of dextranase by Paecilomyces lilacinus were investigated. Effect of various carbohydrates on dextranase formation was examined, dextran was the best C-source and as an inducer. The effect of dextran with different molecular weight (from 17.2 to 1000 kD) on dextranase formation was compared, productivity of dextranase increased with increase of dextran molecular weight. When dextran of 1000 kD was used as C-source. The enzyme formation was 40% higher than that 17.2 kD dextran. When other sugars were separately added to the medium with dextran, the enzyme formation was repressed. Besides C-source, the other optimum conditions of dextranase formation were as follows: N-source, beef peptone; medium initial pH, 6.0-7.0; culture temperature, 28 degrees C; inoculum amount about 10%, and the organism was cultivated for 6 days on 200 r/min shaker in 250 ml flasker with 50 ml medium.

Carbohydrates↗
PubMed1992

[Study on the recovery of 4 types of cultured cell after contacting varieties of dental casting alloys].

Four types of cultured cell (Gin-1, Chang Liver, HEP-2 and L-929) were used in vitro to determine the cytotoxicity of 12 Chinese-Japanese Dental Casting Alloys from cell recovery ability. A new cytocompatibility detecting method--cell recovery test was established and recommended. This method can be able to observe the state of cell recovery through self growth cycle, diminish the side-effect of dead cell and its products on the living cells, nearly mimic the environment in vivo and study the inherited toxicology of cells. The application of computer photo-pattern analysis technique can acquire the objective and accurate data directly.

Animals↗