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T Yan

Publications and source records attributed to T Yan.

61 records · Page 4Linked to original sources
PubMed1992

Antibody binding to a collagen type-II epitope gives rise to an inhibitory peptide for autoreactive T cells.

It is well documented that antigen recognition by T cells requires small peptides which are generated by protein cleavage in antigen-presenting cells. These peptides have to associate with major histocompatibility complex (MHC) molecules in order to be recognized. An inhibitory peptide may bind to the same site of the MHC-encoded protein but is not recognized by the T cell. Here we describe a stimulatory and an inhibitory peptide sequence within human collagen type II (CII) as defined by means of the same autoreactive human T cell clone. Most interestingly, the inhibitory peptide is not generated by regular processing in peripheral blood mononuclear cells but only in the presence of an antibody that binds to the same domain and thereby seems to protect the inhibitory sequence. This finding may indicate that certain autoantibodies have the potential to block autoreactive T cells with specificity for a distinct epitope on the same antigen.

Amino Acid Sequence↗
PubMed1992

Alterations in intracellular lymphocyte metabolism induced by infection and injury.

The effects of burn injury and sepsis on intracellular lymphocyte metabolism were evaluated using a rat model. Adult Lewis rats were subjected to a sham burn, a 30% full-thickness burn, or a 30% full-thickness burn which was infected with Pseudomonas aeruginosa. One week later the animals were sacrificed, and the splenic lymphocytes were harvested and cultured for 24 hr with mitogen stimulation. Lymphocytes from the burned-infected rats were found to utilize more glucose and certain amino acids than did lymphocytes obtained from the other two groups. Lymphocytes obtained from the burned-infected group had lower levels of the immunologically important enzyme, adenosine deaminase, than did the lymphocytes obtained from the other two groups. In summary, sepsis appears to alter a number of intracellular lymphocyte metabolic processes. These alterations may be found to be predictive of early sepsis.

Adenosine Deaminase↗
PubMed1992

Thromboxane/prostacyclin balance in type II diabetes: gliclazide effects.

We studied serum thromboxane (TXB2), the prostacyclin metabolite, 6-keto-PGF1 (6KPGF1) glucose, insulin, and lipid/lipoprotein profiles in 27 patients with non-insulin-dependent diabetes mellitus (NIDDM) who were switched from therapy with glibenclamide (GLB) (with [GLBH] or without phenformin) to gliclazide for 3 months. We found that therapy with gliclazide was followed by a decrease in serum TXB2 (281.8 +/- 128.3 to 149.1 +/- 77.0 mg/L, P less than .001) and an increase in serum 6KPGF1 (60.5 +/- 19.1 to 96.0 +/- 40.3 mg/L, P less than .001). This was accompanied by a decrease in total and low-density lipoprotein (LDL) cholesterol and an increase in high-density lipoprotein (HDL) cholesterol, within the HDL3 cholesterol fraction. These changes were seen despite the fact that neither fasting plasma glucose nor insulin changed with therapy. These findings suggest that gliclazide may have beneficial actions on cardiovascular risk factors in these NIDDM patients.

Diabetes Mellitus, Type 2↗
PubMed1992

[Usefulness of transcutaneous gas monitoring during hemorrhagic shock].

This study was undertaken to confirm whether transcutaneous (tc) gas analysis during hemorrhagic shock could be used as an alternative to mixed venous gas analysis. Tc gases were measured and correlated with arterial and mixed venous gases in 10 anesthetized dogs during hemorrhagic shock and volume resuscitation. Throughout this experiment PtcO2 correlated well with PvO2 (r = 0.78, P less than 0.01), while PaO2 remained mostly constant, and PtcCO2 correlated well with PvCO2 (r = 0.82, P less than 0.01) rather than with PaCO2 (r = 0.63, P less than 0.01). A more detailed observation showed that during progressively decreased cardiac output, PtcO2 became lower than PvO2 and PtcCO2 became higher than PvCO2. We inferred from these observations that the changes of tc and mixed venous gases reflected those gases in tissues and that during severe shock maldistribution of peripheral blood flow prevented mixed venous gases from coming into equilibrium with tissue and tc gases. We conclude that the measurement of tc gases during shock is a more convenient and more reliable monitor of tissue gases than mixed venous analysis.

Animals↗
PubMed1991

[Study on polyorganotropism and host transfer of Pagumogonimus skrjabini in rat].

40 days after oral infection of rat with metacercariae of Pagumogonimus skrjabini, a few worms matured sexually in the abdominal cavity or worm-cysts formed in the lungs, while juveniles were detected in the muscles. 60-90 days after infection, worm-cysts can not only be detected in the lungs, but also in the liver, mediastinum and abdominal wall, with mature or premature worms and eggs. It is suggested that P. skrjabini could mature in rat and showed a phenomenon of polyorganotropism. By means of host-transfer with small juveniles, a part of them migrated to the lungs and matured, but the worms detected in muscles were still stunted.

Animals↗
PubMedDate not supplied

Regulation of osteoclastogenesis and RANK expression by TGF-beta1.

Transforming growth factor-beta (TGF-beta) has been shown to both inhibit and to stimulate bone resorption and osteoclastogenesis. This may be due, in part, to differential effects on bone marrow stromal cells that support osteoclastogenesis vs. direct effects on osteoclastic precursor cells. In the present study, we used the murine monocytic cell line, RAW 264.7, to define direct effects of TGF-beta on pre-osteoclastic cells. In the presence of macrophage-colony stimulating factor (M-CSF) (20 ng/ml) and receptor activator of NF-kappaB ligand (RANK-L) (50 ng/ml), TGF-beta1 (0.01-5 ng/ml) dose-dependently stimulated (by up to 120-fold) osteoclast formation (assessed by the presence of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and expression of calcitonin and vitronectin receptors). In addition, TGF-beta1 also increased steady state RANK mRNA levels in a time- (by up to 3.5-fold at 48 h) and dose-dependent manner (by up to 2.2-fold at 10 ng/ml). TGF-beta1 induction of RANK mRNA levels was present both in undifferentiated RAW cells as well as in cells that had been induced to differentiate into osteoclasts by a 7-day treatment with M-CSF and RANK-L. Using a fluorescence-labeled RANK-L probe, we also demonstrated by flow cytometry that TGF-beta1 resulted in a significant increase in the percentage of RANK+ RAW cells (P < 0.05), as well as an increase in the fluorescence intensity per cell (P < 0.05), the latter consistent with an increase in RANK protein expression per cell. These data thus indicate that TGF-beta directly stimulates osteoclastic differentiation, and this is accompanied by increased RANK mRNA and protein expression.

Acid Phosphatase↗