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Biomedical subjects

T Yan

Publications and source records attributed to T Yan.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Time selection for RA synovectomy].

OBJECTIVE: To discuss the time selection for RA synovectomy. METHOD: Eighty-six knees in 64 RA patients underwent synovectomy in 7 years. 8 of the 64 patients were in RA stage I, 26 in II, 24 in III, 8 in IV. The mean age was 43.9 years and the average follow-up period lasted 38.2 months. RESULTS: Pain relief and swelling reduction were significant clinical features after synovectomy. The overall assessment of the effect of synovectomy showed satisfactory results (72.9%) including all RA-I, and RA-II (87.2%). CONCLUSION: If the patients have sustained or intractable joint swollening with exuberant synovium after strict drug therapy over half a year, synovectomy is an appropriate consideration, it is very important to select the time for synovectomy.

Adolescent↗
PubMed1998

Contribution of the absence of aspartic acid at position 57 of the HLA-DQ beta chain to predisposition to insulin-dependent diabetes mellitus in a southern Chinese population.

OBJECTIVE: To investigate the association of the absence or presence of aspartic acid at position 57 of the HLA-DQ beta chain (NA or A) with susceptibility or resistance to insulin-dependent diabetes mellitus (IDDM) in a Southern Chinese population. METHODS: Sixty-nine IDDM patients and 47 healthy controls in a Southern Chinese population were HLA-DQB1 genotyped by one-step sequence specific polymerase chain reaction (ssPCR). RESULTS: The frequencies of NA and A were 64.5% and 35.5% in the IDDM patients, and 40.4% and 59.6% in the control subjects respectively (RR for NA was 2.68, P < 0.01). The frequencies of NA/NA, NA/A and A/A phenotypes were 47.8%, 33.3% and 18.8% in the IDDM patients, and 31.9%, 17.0% and 51.1% in the controls respectively (P < 0.01). The frequency of A/A phenotype was significantly lower in the IDDM patients than in the control subjects (RR = 0.22, P < 0.01). DQB1* 0302 and DQB1* 0201 were more frequent in IDDM patients than in control subjects. The younger the age of IDDM onset, the higher the allele frequencies of DQB1* 0201 and DQB1* 0302. CONCLUSION: The present study suggests that the NA confers the susceptibility to IDDM, while the A confers the protection against IDDM in patients of Southern Chinese origin. These associations are more clearcut in childhood-onset IDDM patients.

Adolescent↗
PubMed1998

[Effects of simulated microgravity on the distribution of 45Ca2+ in asparagus].

In order to find out the effects of microgravity on the distribution of Ca2+ in asparagus seedlings, tropic reaction of rhizome, the response of cells and organizations, as well as the distribution and transportation in organization under simulated microgravity condition were observed by means of 45CaCl2 labelled autoradiography. The results showed that the distribution of calcium cations highly correlated with gravity. The absorption, distribution and transportation of calcium were greatly affected by gravity.

Calcium↗
PubMed1998

[Experimental studies on development of Paragonimus heterotremus in rats].

AIM: To study the polymorphism of the development of Paragonimus heterotremus in rats and to ascertain the host nature of the rat. METHODS: SD and Wistar rats were each infected orally with 100 metacercariae of P. heterotremus. The distribution and development of the worms recovered from rats 14-156 days after infection were observed. RESULTS: Thirty days after infection, reproductive organs appeared in the worms recovered from the body cavities. Seventy days after infection, worm-cysts were found in the lungs, livers and pleural wall, the worms in the cysts matured but the worms detected in the muscles were still stunted on the 156 th day after infection. CONCLUSION: Rat is the definitive host and paratenic host of P. heterotremus. The development of P. heterotremus is polymorphic.

Animals↗
PubMed1997

Adenovirus-mediated manganese superoxide dismutase gene transfer to hamster cheek pouch carcinoma cells.

As a first step in evaluating the tumor suppressor activity of the manganese superoxide dismutase (MnSOD) gene on established tumors in vivo, we used adenovirus-mediated gene transfer as a means of delivering the MnSOD cDNA to hamster cheek pouch carcinoma (HCPC-1) cells in vitro. HCPC-1 cells were transduced with the adenovirus-MnSOD construct (AdMnSOD) at multiplicities of infectivity (MOI) of 0, 10, 25, 50, 100, 150, and 200 MOI or with the adenovirus-LacZ reporter gene construct (AdLacZ) at 100 MOI. Dose-dependent increases in MnSOD immunoreactivity were seen on Western blotting and indirect immunofluorescence microscopy with increasing AdMnSOD titers. Maximal immunoreactivity was observed at 100 MOI AdMnSOD with both techniques. Moreover, we observed a concomitant 6-7-fold increase in MnSOD activity compared with parental cell levels that also peaked at 100 MOI AdMnSOD. To determine the effect of transgene-expressed MnSOD on tumor cell behavior, we examined cell growth, plating efficiency, and anchorage-dependent growth in soft agar. Cell number measured on day 13 decreased approximately 50% with 100 MOI AdMnSOD (P < 0.05) compared with parental cells. Moreover, cell doubling time increased from 38 to 44 h with 100 MOI AdMnSOD. Plating efficiency and cell growth in soft agar decreased approximately two-thirds with 100 MOI AdMnSOD (P < 0.001). These assays of the transformed phenotype in vitro all appeared to show maximal effect with 100 MOI AdMnSOD. As tumor growth in vivo is most predictable by a combination of these in vitro data, our results suggest that if MnSOD can be effectively delivered to a tumor in vivo using the adenovirus paradigm, effective tumor growth suppression can be observed.

Adenoviridae↗
PubMed1997

Rapid identification and isolation of zebrafish cDNA clones.

A fast and economical approach, referred to as cDNA clone tagging, was adapted to identify and isolate zebrafish cDNA clones. The basic approach was to partially sequence the coding region of size selected cDNA clones and the partial sequences were then used as tags for identifying the clones through homology search. To benefit maximally from the tagging approach, two cDNA libraries, derived from embryonic and adult fish poly(A)+ RNAs, respectively, were constructed by unidirectional cloning; conceptually, they have the potential to represent all expressed zebrafish genes. A total of 1084 clones were sequenced from the two libraries, and 511 clones were identified, based on sequence homology. These identified clones were derived from at least 261 genes, encoding 48 translational machinery proteins, 47 cytosolic proteins, 43 cytoskeletal proteins, 41 nuclear proteins, 32 membrane proteins, 22 secreted proteins, 20 mitochondrial proteins and 8 proteins with an unknown location. Of the 261 distinct cDNA clones identified, 254 were isolated for the first time in the zebrafish. These tagged cDNA clones, identified and unidentified, provide rich resources for developmental analysis as well as mapping of zebrafish genome. The long-term objective of this study is to establish a tagged zebrafish gene library that can be accessed both by hybridization screening against the plasmid DNAs and by electronic screening using the sequence information.

Animals↗
PubMed1997

[Treatment of posterior urethral break caused by pelvic fracture and inflammatory urethral stricture via laying three silicone tubers into urethra].

We investigated a new approach for the treatment of posterior urethral break caused by pelvic fracture and inflammatory urethral stricture. 7-10 days after the operation of urethral realignment on patients with urethral break caused by pelvic fracture or after forced dilatation of inflammatory urethral stricture, three silicone tubers were laid into urethra and kept there for three months. In 66 cases of urethral break, the cure rate (58/66) was 87.9%, the improving rate (2/66) 3.0% and the failure rate (6/66) 9.1%. In 15 cases of inflammatory urethral stricture, the recovery rate was 100%. In this group of 81 cases, the cure rate was 92.6% and failure rate was only 7.4%. This new therapeutic approach proved to be simple, safe and effective. It could also dramatically reduce the infection or the stricture of urethra.

Adolescent↗
PubMed1996

Manganese-containing superoxide dismutase overexpression causes phenotypic reversion in SV40-transformed human lung fibroblasts.

Manganese superoxide dismutase (MnSOD) has been found to be low in a wide range of tumor cells as well as in vitro-transformed cell lines and has been implicated as a new type of tumor suppressor gene. The relationship between MnSOD activity and the malignant phenotype was studied by transfection of MnSOD cDNA into the SV40-transformed human fibroblast cell line WI-38 VA13 subline 2RA. The integration and expression of the exogenous MnSOD cDNA was confirmed in three selected clones with a 2-3.5-fold increase in MnSOD activity. The effect of elevated expression of MnSOD on the cell phenotype was determined by observing growth characteristics. Compared with the parental and neo control cells, the MnSOD-overexpressing clones had a slower growth rate, lower plating efficiency, increased anchorage dependence, and morphological differences. These changes were correlated strongly with the level of MnSOD activity. The results suggest that an increase of MnSOD activity can reverse part of the malignant phenotype in SV40-transformed human fibroblast cells. A possible mechanism is that overexpression of MnSOD might alter the intracellular redox state by modulation of the balance of reactive oxygen species.

Cell Division↗
PubMed1996

Inhibition of cell growth and sensitization to oxidative damage by overexpression of manganese superoxide dismutase in rat glioma cells.

The effects of overexpression of human manganese superoxide dismutase (MnSOD) on cell proliferation and response to oxidative stress in rat glioma cells were studied. MnSOD-overexpressing cells had a 2- to 14-fold increase in MnSOD activity, but did not have consistent changes in the activities of CuZnSOD, catalase, or glutathione peroxidase. Cells with more than a 5-fold increase in MnSOD activity became more sensitive to radiation, 1,3-bis(2-chloroethyl)-1-nitrosourea, and buthionine sulfoximine and had a lower growth rate than parental and vector control cells. The sensitivity to 1,3-bis(2-chloroethyl)-1-nitrosourea was partially reduced by pyruvate, a H2O2 scavenger. Our results suggest that overexpression of MnSOD can cause an imbalance of antioxidant enzymes, which we hypothesize results in an elevation of intracellular H2O2. Overexpression of MnSOD can either inhibit cell proliferation or increase cell death by oxidative agents, depending on the levels of peroxide-removing enzymes.

Animals↗
PubMed1996

Age-of-onset related HLA-DQA1 genetic heterogeneity of insulin-dependent diabetes mellitus.

OBJECTIVE: To clarify whether there is an association of insulin-dependent diabetes mellitus (IDDM) susceptibility with HLA-DQA1 locus in adult-onset IDDM. PATIENTS AND METHODS: Possible heterogeneity in immunogenetic aspects was investigated by comparing the findings on relationship between HLA-DQA1 52 Arg(+) and IDDM predisposition in three groups with different ages of IDDM onset (group A 14 years, group B 15-30 years, group C > 31 years). RESULTS: The frequency of HLA-DQA1 52 Arg(+) in group A (87.5%) was higher than that in control (53.9%, P < 0.05) and in group B and C (P < 0.05). The frequency of HLA-DQA1 52 Arg(+)/Arg(+) phenotype in group A (75%) was higher than that in group C (23.1%, P < 0.05). CONCLUSION: The contribution of HLA-DQA1 52 arginine to IDDM susceptibility is heterogeneous. Further study is necessary to clarify the immunogenetic entity of IDDM.

Adult↗
PubMed1995

[Changes in cytosolic free calcium and thromboxane B2 synthesis in platelets from diabetic subjects].

Using fura-2, a fluorescence indicator, we evaluated the changes of platelet cytosolic free calcium concentration ([Ca2+]i) and its role in regulation of thromboxane B2 (TXB2) synthesis in patients with diabetes mellitus (DM group, n = 27) and in healthy subjects (control group, n = 15). The A23187-evoked elevation of [Ca2+]i and TXB2 production were higher in the DM group than in the control group (P < 0.01 respectively). The rise in [Ca2+]i was correlated positively with TXB2 production. In contrast, stimulation with arachidonic acid, TXB2 production was unaltered between the groups, although arachidonate-induced [Ca2+]i was higher in the DM group than in the control group (P < 0.05). The results suggested that changes in platelets [Ca2+]i in diabetic subjects may contribute to increase in TXB2 synthesis, involved libration of free arachidonate from membrance phospholipids by the action of phospholipases. Since no significant difference was found between the diabetic patients with microangiopathy (n = 13) and without microangiopathy (n = 14), the results above may be involved in the development of diabetic microangiopathy.

Biological Transport, Active↗
PubMed1994

The effect of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells.

Here we have investigated and compared the effects of anti-CD4 on helper function of CD4,45RA+ versus CD4,45RO+ T cells. Only CD4,45RO+ cells, but not CD4,45RA+ cells were able to promote B cell differentiation resulting in immunoglobulin production in vitro (IgM as well as IgG) which could be inhibited by anti-CD4 MoAbs (MAX.16H5 and T151). In pokeweed mitogen (PWM)-induced B cell proliferation a similar pattern of responsiveness was obtained. When we studied the anti-CD4 effects on cytokine production in T cells stimulated in mixed lymphocyte reaction (MLR) or by mitogens, we found that neither IL-2 nor IL-4 production was dramatically influenced by anti-CD4 in CD4,45RO+ cells. This led us to the conclusion that the inhibitory effect of anti-CD4 on B cell proliferation and immunoglobulin secretion was not due to inhibition of cytokine production. To clarify this point, we investigated the ability of anti-CD4 to inhibit conjugate formation between B and T cells. It was found that CD4,45RO+ T cells formed more conjugates than CD4,45RA+ cells, and that only the conjugate formation by CD4,45RO+ T cells was inhibited by anti-CD4. These results suggest that (i) anti-CD4 inhibits T helper functions primarily by affecting CD4,45RO+ cells, and (ii) this effect is probably mediated by contact inhibition in the early phase of T-B collaboration.

Antibodies, Monoclonal↗
PubMed1994

[The usefulness of transcutaneous gas monitoring during hemorrhagic shock; discrepancy between the two transcutaneous gas tensions of anterior thorax and femur].

We measured transcutaneous gas tensions of both anterior thorax and femur. The differences between the two transcutaneous gas tensions were compared, as well as the relationship between the two transcutaneous and mixed venous blood gas tensions, in 10 dogs during hemorrhagic shock. The changes in femoral transcutaneous gas tensions correlated better with the changes in mixed venous gas tensions. The correlation between the two transcutaneous gas tensions were fairly good (oxygen tensions; r = .827, carbon dioxide tensions; r = .867). However, the discrepancy between the two gas tensions became greater in severe shock. Hence, oxygen tensions became smaller and carbon dioxide tensions became greater on femur than on anterior thorax. This indicates the possibility of "maldistribution of blood flow", which has already been detected between vital organs and skin, also exists between peripheral and central skin. Therefore, transcutaneous gas tensions should be monitored at peripheral skin, where gas tensions show greater changes and reflect systemic perfusion precisely than at central skin, during shock.

Animals↗
PubMed1993

Evidence for Kupffer cell activation by burn injury and Pseudomonas exotoxin A.

Postburn metabolic and immunological alterations may in part be due to translocation of gut exotoxin and endotoxin, which can result in tumour necrosis factor (TNF) and prostaglandin E (PGE) production by macrophages. We evaluated the effect of burn injury, plus exotoxin and endotoxin on TNF-alpha and PGE production by Kupffer cells, and peritoneal macrophages. Adult Wistar rats underwent 30 per cent TBSA burn or sham burn. Kupffer cells were harvested from rat livers and peritoneal macrophages from the abdominal cavity 24 h postburn. They were cultured overnight at 1 x 10(6) cells/ml and stimulated with saline, 5 micrograms/ml of Pseud. aeruginosa Exotoxin A (Exo-A), 5 micrograms/ml of Pseud. aeruginosa Endotoxin (Endo), Exo-A + Endo, or Exo-A + Endo + the PGE derivative 16,16 dimethyl-PGE (dPGE) (10 micrograms/ml). The supernatants were harvested after 4, 24 and 48 h of culture and assayed for TNF-alpha and PGE. Results showed that burn injury induced an increase in TNF-alpha and PGE production by Kupffer cells stimulated with Exo-A, Endo, and both Exo-A + Endo (P < 0.05). The release of TNF-alpha by Kupffer cells was downregulated by exogenous PGE (P < 0.05). The increased TNF-alpha production was inversely related to PGE levels. In conclusion, both burn injury and Exo-A potentiate the responsiveness of Kupffer cells and peritoneal macrophages to endotoxin as measured by the rate of production of TNF-alpha and PGE. PGE may locally downregulate the immune response by limiting Kupffer cells' and peritoneal macrophages' TNF-alpha production.

ADP Ribose Transferases↗
PubMed1992

Specificity and T cell receptor beta chain usage of a human collagen type II-reactive T cell clone derived from a healthy individual.

Collagen type II (CII) is a cartilage-specific matrix compound well known as an inducer of an experimental, T cell-dependent autoimmune arthritis, a disease which shows some similarities to human rheumatoid arthritis. Here we report on an HLA-DR7-restricted human CD4 T cell clone (TC9), which was isolated from a healthy donor and recognizes human CII. After screening CNBr fragments of CII and tryptic fragments derived thereof, the T cell epitope could be mapped to amino acid residues 271-285 of the triple helical region of CII that are located within CNBr fragment 11 [alpha 1 (II) CB11]. This epitope was confirmed by a synthetic peptide stimulatory for TC9. The T cell receptor beta chain of TC9 was cloned using the polymerase chain reaction; it comprises V beta 6.7 and contains besides J beta 2.3 and C beta 2 an as yet undescribed sequence for the D segment.

Adult↗