Biomedical subjects

W Yang

Publications and source records attributed to W Yang.

At least 325 records · Page 18Linked to original sources

PubMed1998

[The clinical effect of ATG and OKT3 on the treatment of refractory rejection after cadavaric kidney transplantation].

OBJECTIVE: To observe the effect of ATG and OKT3 on the treatment of refractory rejection, including acute and chronic rejection after cadaveric kidney transplantation. METHOD: 87 patients with refractory rejection after cadaveric kidney transplantation were treated by using ATG (13 patients) and OKT3 (74). A total dose of 1 000 mg for ATG group or 45 mg for OKT3 group was administered for each patient. RESULT: Two accelerating rejection and acute rejection were reversed and 7 in the ATG group, 90.00% (27/30) and 90.47% (38/42) in the OKT3 group respectively. A significant difference of total reverse rates was seen between the ATG and OKT3 groups (69.23% verse 90.28%, P < 0.05). In retransplant patients, the reverse rate of acute rejection by OKT3 was 91.67% (11/12). But OKT3 did not show any effect in patients with chronic rejection. CONCLUSION: OKT3 is better than ATG for reversing the refractory rejection, especially in retransplant patients, but it has no any effect on chronic rejection.

Adolescent↗

PubMed1998

[An ultrasound biomicroscopic study on changes of the structure of ocular anterior segment after topical application of cycloplegia].

OBJECTIVE: To observe the changes of ocular anterior segment and the relation between the intraocular pressure (IOP) and these changes after the topical application of cycloplegia using ultrasound biomicroscope (UBM), especially to observe the changes of ciliary body thickness and ciliary body-lens distance. METHODS: The quantitative measurement of UBM and the measurement of IOP had been done in 48 normal eyes before and after the topical use of 2% homatropine solution. The results were statistically analyzed. RESULTS: In the parameter reflecting the change of the anterior chamber angle after using 2% homatropine, the trabecular iris angle decreased, the angle open distance 250 decreased, the iris thickness 1 increased, the anterior chamber became deeper and the iris-lens contact distance became shorter, and all these differences were statistically significant (P < 0.05). In the parameter reflecting the changes of ciliary body, the ciliary body thickness and the ciliary process thickness decreased, the scleral ciliary body angle increased, the iris-zonule distance decreased and the ciliary body-lens distance increased, and all these differences were significant statistically (P < 0.05). The IOP increased from 2.35 +/- 0.46 kPa to 2.43 +/- 0.47 kPa after the topical use of 2% homatropine, but the differences were not statistically significant (P > 0.05). CONCLUSIONS: After the topical application of cycloplegia, the anterior chamber becomes deeper, the anterior chamber angle becomes narrower, the ciliary body becomes thinner and moves backward and the ciliary body-lens distance increases. By using UBM the structure of ocular anterior segment in its moving state can be observed and these structures can be measured quantitatively. The ultrasound biomicroscopic imaging has its advantages in the morphological study of ocular anterior segment.

Adult↗

PubMed1998

[Secondary surgical management of massive suprachoroidal hemorrhage].

OBJECTIVE: To evaluate the surgical techniques and the efficacy for massive suprachoroidal hemorrhage (MSH). METHODS: Secondary surgery performed on 11 cases of MSH occurring during or after intraocular surgery was delayed for 11 to 28 days (mean, 15.4 days). All eyes underwent posterior drainage sclerotomies under constantly maintained limbal fluid line pressure, followed by pars plana infusion and vitreoretinal surgery. The perfluorocarbon liquid was used intraoperatively in 6 cases. RESULTS: The drainage of the choroidal hemorrhage was successful in all cases. The blood drained from suprachoroidal space was completely liquified and chocolate in color. Tractional retinal detachment occurred in 2 eyes; 9 eyes had retinas normal in position. The mean follow-up was 7.8 months. Visual acuities were improved, >or=0.1 in 6 eyes. CONCLUSION: Immediate management of MSH includes watertight wound closure and medical treatment for elevated intraocular pressure, and secondary surgery was performed timely, including external drainage by creating sclerotomies and vitreoretinal surgery. The above methods of treatment have certain advantages and are promising for the management of MSH.

Adolescent↗

PubMed1998

[Application of ultrasound microscope for the reattachment surgery of detachment of ciliary body].

OBJECTIVE: To evaluate the advantages of ultrasound biomicroscope (UBM) used for the reattachment surgery of traumatic ciliary body detachment. METHODS: 33 cases diagnosed by UBM as ciliary body detachment were studied. The surgical results of these cases were analyzed and compared with that of 83 cases which were simply diagnosed by a gonioscope. RESULTS: 31 of the 33 cases regained the normal intraocular pressure (IOP) after once of operation (94%), and all cases achieved successful results after twice of operation (100%). Of the 83 cases examined only by gonioscopy, the rates of reaching normal IOP after the 1(st), 2(nd) and 3(rd) operations were 82%, 94% and 96% respectively. CONCLUSIONS: These results suggest that the UBM be useful for the tiny and narrow detachment of ciliary body which can not be seen by a gonioscope. UBM has important clinical value in diagnosis, guide to the range of suture and follow-up observation. With the use of UBM, the frequency of operation necessary for surgical success and blindness in action in the operation will be reduced, and the successful rate of once of operation will be increased significantly.

Adolescent↗

PubMed1998

[Effects of emodin on the activity of K channel in guinea pig taenia coli smooth muscle cells].

The effects of emodin, cromakalim (KATP channel opener) glybenclamide (KATP channel inhibitor) Ba2+ and TEA on the electrical and contractive activities of the smooth muscle cells in guinea pig taenia coli and the relationship between emodin and four other drugs were studied by using intracellular microelectrode technique and the tension measuring technique. The results are as follows: (1) Emodin enhances the electrical and contractive activities of the smooth muscle cells in guinea pig taenia coli. The effects of emodin depend on its concentration. (2) Emodin can resist the inhibition of cromakalim on the electrical and contractive activities of smooth muscle cells. On the other hand, cromakalim was shown to suppress the effects of emodin. (3) Ba2+, TEA and glybenclamide all can improve the electrical and contractive activities of smooth muscle cells and resist the inhibition of cromakalim. The effects of emodin were found to be similar to that of glybenclamide but different from that of Ba2+ and TEA. The results suggest that the mechanism of action of emodin is to inhibit the activity of KATP channel in the guinea pig taenia coli smooth muscle cells.

Animals↗

PubMed1998

[Field trials on the efficacy of albendazole composite against intestinal nematodiasis].

AIM: To study the anthelmintic effect of albendazole composite (containing 67 mg of albendazole and 83.3 mg base of pyrantel pamoate per tablet). METHODS: A randomized controlled study was carried out to compare the efficacy of a single dose of 3 or 2 tablets of albendazole composite versus a single dose of 400 mg of albendazole or 10 mg base/kg of pyrantel pamoate for treatment of intestinal nematodiasis including 1,864 cases infected with hookworm, 1,568 cases infected with Ascaris, 1,785 cases infected with Tricuris trichiura and 373 children infected with Enterobius vermicularis. RESULTS: In adults, the egg negative conversion rate of a single dose of 3 or 2 tablets of albendazole composite reached 65.0% and 52.7% for hookworm infection (P < 0.01), 100% and 100% for Ascaris infection, and 26.5% and 19.2% for Trichuris infection (P < 0.01), respectively. There were significantly better effect against hookworm with 3 tablets of albendazole composite than that with single albendazole or pyrantel pamoate (65.0% vs. 47.6% and 38.5%, P < 0.01). The effect of 2 tablets of albendazole composite against hookworm was also higher than that of single pyrantel pamoate (P < 0.01) and equal to single albendazole but the anthelmintic effect against Trichuris infection was lower than that of single albendazole (19.2% vs. 26.5%). In 2-6-year-old children, the effect of 1.5 tablets of albendazole composite against Enterobius vermicularis infection showed an egg negative conversion rate of 100% which was higher than that of single pyrantel pamoate (100% vs. 83.0%, P < 0.01). The worm collection data showed that the worm-expelling action of albendazole composite was much more rapid than that of albendazole. There were no adverse effects of albendazole composite on blood picture, liver or renal function and ECG. The side effect of both 3 and 2 tablets of albendazole composite was mild and transcient. CONCLUSION: Albendazole composite exhibits a synergistic effect of both albendazole and pyrantel pamoate.

Adolescent↗

PubMed1998

[Establishment of Hymenolepis diminuta-animal model and morphology of cysticercoid].

AIM: To observe the morphological changes in the process of the development of Hymenolepis diminuta. METHODS: The life cycle of Hymenolepis diminuta was established between Rattus domesticus albus and Triboliun castaneum. The morphology of cysticercoid were observed microscopically, and the ultrastructure of the body surface of cysticercoid were observed by scanning electron microscopy. RESULTS: Three phases including the mature stage, the blister stage and the protective outer membrane-forming stage during the growing course of cysticercoid were observed microscopically. Under scanning electron microscope, lots of sieve-like micropores on the surface of mature cysticercoid were seen in the second week after infection. The blister phase was found in the third week and the outer membrane measuring about 45 microns in thickness were found surrounding the cysticercoid and vesicular surface, forming a smooth cyst wall in the fourth week. CONCLUSION: The life cycle of Hymenolepis diminuta has been established in the animal-model. The finding of the three phases during the growing course of cysticercoid is reported for the first time.

Animals↗

PubMed1998

Effect of cataract surgery on ocular axial length elongation in young children.

PURPOSE: To evaluate the influence of cataract surgery on eyes of children between 1-5 years old. MATERIALS AND METHODS: Forty-seven cases of pediatric cataract, including 31 cases of bilateral congenital cataract and 16 cases of unilateral posttraumatic cataract, were retrospected. Of the 31 cases of congenital cataract, 19 cases (group 1) had undergone cataract extraction with intraocular lens (IOL) implantation, 12 (group 2) had undergone cataract extraction without IOL implantation. Each of them had their two eyes operated separately at an interval of 1 year or longer. Of the 16 cases of posttraumatic cataract, 6 (group 3) had undergone cataract extraction with IOL implantation and 10 (group 4) had undergone cataract extraction without IOL implantation. Mean age at the time of interested surgery was 2.9 years (range from 1.1 to 5.1 years). Ocular axial length of both eyes measured by A-scan ultrasonography before and after the surgery of the earlier operated eye in the congenital groups and the operated eye in the post-traumatic groups was recorded. The elongation of axial length of the earlier operated eye in the congenital groups and the operated eyes in the posttraumatic groups of each case were compared with that of the fellow eye statistically with paired t-test. RESULTS: The mean follow-up was 2.6 years (ranged from 1.0 to 6.4 years). In all the 4 groups, the elongation of axial length between the earlier operated eye and later operated eye in the congenital groups and between the operated and unoperated eyes in the posttraumatic groups of each case was not significantly different (p > 0.05). CONCLUSION: Cataract surgery, either extraction with or without IOL implantation, did not retard axial elongation in children above 1 year old.

Age Factors↗

PubMed1998

Serial in vivo observations of cerebral vasculature after treatment with a large single fraction of radiation.

To test whether single high doses of radiation, similar to those used with radiosurgery, given to normal cerebral vasculature can cause changes in leukocyte-vessel wall interactions and tissue perfusion, a rat pial window model was used to view the cerebral vasculature, facilitating repeated in vivo observations of microcirculatory function. An attachment for a 4 MV linear accelerator was designed to deliver a well-collimated 2.2-mm beam of radiation to a selected region of rat brain. Sequential measurements of leukocyte-endothelial cell interactions, relative change in blood flow with laser Doppler flowmetry and vessel length density were performed prior to and at 24 h and 3 weeks after treatment with 15, 22.5 or 30 Gy, given in a single fraction. Significant increases in leukocyte-endothelial cell interactions were seen 24 h and 3 weeks after irradiation that were dependent on dose, particularly in arteries. Changes were apparent in both arteries and veins at 24 h, but by 3 weeks the effects in arteries predominated. Decreases in vessel length density and blood flow were observed and became greater with time after treatment. A variety of morphological changes were observed in irradiated arteries, including formation of aneurysmal structures, endothelial denudation and thrombus formation. These results suggest that: (1) An increase in leukocyte-vessel wall interactions occurs after irradiation; (2) cerebral arterioles are more sensitive than veins to radiation administered in this fashion; and (3) the increase in leukocyte-vessel wall interactions likely contributes to reduction of or loss of arteriolar flow, with resultant loss of flow to dependent microvascular vessels.

Animals↗

PubMed1998

Upregulation of Epstein-Barr virus-encoded latent membrane protein by human herpesvirus 6 superinfection of EBV-carrying Burkitt lymphoma cells.

The effect of HHV-6 strain A infection on the expression of Epstein-Barr virus- (EBV-) encoded growth transformation-associated genes in two EBV-positive Burkitt lymphoma cell lines, Akata and P3HR-3, was investigated. The results indicate that HHV-6A upregulates the expression of the latent membrane protein LMP-1 in both cell lines. Expression of EBNA-2 was also upregulated in Akata cells following HHV-6A infection. Transfection of reporter constructs carrying the LMP-1 regulatory sequences (LRS; -634/+40) or its 5' deleted derivatives in Akata and in a T-lymphoblastoid cell line, J-Jhan, confirmed the presence of positive and negative regulatory elements responsive to HHV-6A infection in LMP-1 regulatory sequence (LRS). The majority of LRS constructs were under the influence of dominant negative factors. HHV-6A was able to override the effect of such factors acting on reporter plasmids containing the -634/-54, -324/-54, -214/-54, and -106/-54 parts of LRS. The plasmid that carried only the -54/+40 LRS region was constitutively active in both Akata and J-Jhan cells; in Akata, its activity was influenced by HHV-6A. The finding that HHV-6A infection may activate LMP-1 and EBNA-2 expression, which is essential for the immortalization of B-lymphocytes by EBV, shows a novel aspect of the interaction between these two herpesviruses.

Antibodies, Monoclonal↗

PubMed1998

SHP-1 deficiency in B-lineage cells is associated with heightened lyn protein expression and increased lyn kinase activity.

SHP-1 protein tyrosine phosphatase is a critical regulator of signal transduction in hematopoietic cells. In the present study, we derived two pre-B cell lines, PBCL-1 and PBCL-2, from normal and SHP-1-deficient motheaten mice, respectively, and characterized hyperphosphorylated proteins in PBCL-2 cells to identify SHP-1-regulated molecules. Two proteins of 56 and 53 kDa (p56/p53) in PBCL-2 cells showed heightened phosphorylation (3- to 6-fold) in comparison with those in PBCL-1. p56/p53 were identified as the two forms of the lyn protein tyrosine kinase (p56/p53lyn), which showed increased kinase activity in PBCL-2 cells. Interestingly, the protein levels of p56/53lyn were found to be 3- to 6-fold higher in PBCL-2 cells than those in PBCL-1, whereas the transcript levels of lyn in the two cell lines were comparable. A modest increase in p56/53lyn protein expression was also detected in primary spleen B cells of motheaten mice. Thus SHP-1 deficiency in B-lineage cells, especially pre-B cells, is associated with increased lyn protein expression and kinase activity. These data indicate a role for SHP-1 in regulating lyn through a post-transcriptional mechanism.

Animals↗

PubMed1997

An expression system for mammalian amino acid transporters using a stably maintained episomal vector.

Despite its versatility and effectiveness in numerous studies, the vaccinia/HeLa cell expression model may not be optimal for the study of all transport proteins. To evaluate an alternative expression model for amino acid transport Systems ASC and X-AG, the mRNA content and transport activity encoded by human hippocampal ASCT1 cDNA and rat hippocampal EAAC1 cDNA, respectively, were measured in pDR2-cDNA-transfected human embryonic kidney 293 cells made competent by stable transfection with the Epstein-Barr neutral antigen-1 (EBNA-1) cDNA (293c18 cells) to evaluate the EBNA-1/293c18 expression system. The results show that (i) the EBNA-1/293c18 expression system results in a larger increase over background of Systems ASCT1 (6.4x) and EAAC1 (39x) transport activity than does the vaccinia/HeLa expression system (2.6x and 22x, respectively); (ii) transfection and hygromycin B selection for the pDR2 vector do not affect the endogenous transport velocities of Systems ASC, X-AG, or A; and (iii) the endogenous transport velocities of Systems ASC and X-AG in 293c18 cells were not affected by the expression of exogenous EAAC1 or ASCT1. We conclude that the EBNA-1/293c18 cell expression model represents a useful transient expression regimen to characterize mammalian amino acid transport proteins, especially for transporters that may exhibit relatively low activity in transient expression systems lacking a selection mechanism.

Amino Acid Transport System X-AG↗

PubMed1997

The 95-kilodalton membrane glycoprotein overexpressed in novel multidrug-resistant breast cancer cells is NCA, the nonspecific cross-reacting antigen of carcinoembryonic antigen.

Human breast carcinoma MCF-7/AdrVp cells display a novel multidrug resistance phenotype that is characterized by the overexpression of a 95-kDa membrane glycoprotein (p95) and by marked reduction in intracellular anthracycline accumulation, without overexpression of P-glycoprotein or the multidrug resistance protein MRP. p95 is also highly expressed in multidrug-resistant NCI-H1688 cells derived from a human small cell lung carcinoma. Deglycoslyated p95 from NCI-H1688 cells was isolated by two-dimensional gel electrophoresis and then digested with trypsin. The tryptic peptides were analyzed by mass spectrometry and microsequencing. These analyses identified p95 to be identical to NCA-90, the nonspecific cross-reacting antigen related to the carcinoembryonic antigen (CEA). Further confirmation that p95 is indeed NCA-90 was obtained by Northern and Western blot studies using probes or antibodies specific for p95, NCA-90, or CEA family members. Western blot studies also revealed that CEA itself is overexpressed in MCF-7/AdrVp cells compared to parental MCF-7/W cells. The enforced expression of NCA-90 protein in HeLa cells stably transfected with NCA-90 cDNA did not result in increased resistance of the transfected cells to daunorubicin or a decrease in daunorubicin accumulation in the transfected cells compared to cells transfected only with the expression vector. However, a recent report by H. Kawaharata et al. (Int. J. Cancer, 72: 377-382, 1997) of diminished accumulation, retention, and cytotoxicity of doxorubicin in EJNIH3T3 cells in which enforced expression of CEA was accomplished leaves open the possibility that the overexpression of CEA, possibly in combination with that of NCA-90, could account at least in part for the drug resistant phenotype displayed by MCF-7/AdrVp cells.

3T3 Cells↗

PubMed1997

Interruption of G protein-coupling in CXCR2 does not alter ligand binding, but eliminates ligand-activation of GTPgamma35S binding, calcium mobilization, and chemotaxis.

CXCR2 is a seven-transmembrane receptor that transduces intracellular signals in response to the chemokines IL-8, MGSA/GRO, and other ELR motif-containing CXC chemokines by coupling to heterotrimeric GTP-binding proteins. In this study, we have mutated two putative G protein-coupling regions of CXCR2 and characterized the effects of these mutations on ligand-activated signal transductions: aspartic acid 89 in the second transmembrane domain and the HRAMR sequence (BBXXB motif, found in the third intracellular loop where B indicates a basic amino acid and X represents any amino acid). The Asp89 was replaced by either asparagine (D89N) or glutamic acid (D89E). For the BBXXB motif, the first two basic amino acids were mutated to two neutral isoleucines (HR-II), or alternatively, two isoleucines were inserted between alanine and methionine (II-insert). When expressed in human embryonic kidney 293 cells, the D89E mutant was localized intracellularly with no detectable cell surface expression. In contrast, D89N, HR-II, and II-insert mutants displayed cell surface expression, with Kd values and expression levels similar to that of the wild-type transfectant. The ability of the mutants to transduce signal was assessed by ligand-stimulated GTPgamma35S binding, mobilization of intracellular free Ca2+, and chemotaxis assays. Both D89N and HR-II mutants signaled similarly to a wild-type receptor in all three assays. However, the II-insert mutant exhibited a loss of ligand-stimulated GTPgamma35S binding, calcium mobilization, and chemotaxis. Unexpectedly, this receptor underwent ligand-induced sequestration comparable to wild-type CXCR2. These data indicate that Asp89 and the basic amino acids in the third intracellular domain do not play essential roles in ligand-induced signal transduction through CXCR2. However, proper secondary structure and orientation of the third intracellular loop of CXCR2 are essential for ligand-mediated signal transduction but not for receptor sequestration.

Calcium↗

PubMed1997

Site-specific recombination in plane view.

Biochemists have worked long and hard on each reaction component and chemical step to reach the point of asking the question as to how protein and DNA molecules are arranged and rearranged in the process of site-specific recombination. The structures of several lambda integrase family members published recently have answered many of the questions about this process.

Amino Acid Sequence↗

PubMed1997

Gly-Pro-Arg confers stability similar to Gly-Pro-Hyp in the collagen triple-helix of host-guest peptides.

A set of host-guest peptides of the form Ac(Gly-Pro-Hyp)3-Gly-X-Y-(Gly-Pro-Hyp)4-Gly-Gly-NH2 has been designed to evaluate the propensity of different Gly-X-Y triplets for the triple-helix conformation (Shah, N. K., Ramshaw, J. A. M., Kirkpatrick, A., Shah, C., and Brodsky, B. (1996) Biochemistry 35, 10262-10268). All Gly-X-Y guest triplets led to a decrease in melting temperature from the host (Gly-Pro-Hyp)8 peptide except for Gly-Pro-Arg. In this Gly-Pro-Hyp-rich environment, Gly-Pro-Arg was found to be as stabilizing as Gly-Pro-Hyp. Decreased stability of host-guest peptides containing Gly-Pro-Lys, Gly-Pro-homo-Arg, and Gly-Arg-Hyp compared with Gly-Pro-Arg indicated a stabilization that is optimal for Arg and specific to the Y-position. Arg was found to have a similar stabilizing effect when residues other than Pro are in the X-position. Both Arg and Hyp stabilize the triple-helix preferentially in the Y-position in a stereospecific manner and occupy largely Y-positions in collagen. However, contiguous Gly-Pro-Hyp units are highly stable and promote triple-helix folding, whereas incorporation of multiple Gly-Pro-Arg triplets was destabilizing and folded slowly due to charge repulsion. In collagen, Gly-Pro-Arg may contribute maximally to local triple-helix stability while also having the potential for electrostatic interactions in fibril formation and binding.

Amino Acid Sequence↗

PubMed1997

Raman spectral evidence for hydration forces between collagen triple helices.

Hydration forces are thought to result from the energetic cost of water rearrangement near macromolecular surfaces. Raman spectra, collected on the same collagen samples on which these forces were measured, reveal a continuous change in water hydrogen-bonding structure as a function of separation between collagen triple helices. The varying spectral parameters track the force-distance curve. The energetic cost of water "restructuring," estimated from the spectra, is consistent with the measured energy of intermolecular interaction. These correlations support the idea that the change in water structure underlies the exponentially varying forces seen in this system at least over the 13-18-A range of interaxial separations.

Collagen↗

PubMed1997

Cloning and characterization of a novel Cdc42-associated tyrosine kinase, ACK-2, from bovine brain.

Cdc42 plays an important role in intracellular signaling pathways that influence cell morphology and motility and stimulate DNA synthesis. In attempts to determine whether nonreceptor tyrosine kinases play a fundamental role in Cdc42 signaling, we have cloned and biochemically characterized a new Cdc42-associated tyrosine kinase (ACK) from bovine brain. This tyrosine kinase, named ACK-2, has a calculated molecular mass of 83 kDa and shares a number of primary structural domains with the 120-kDa ACK (ACK-1). The main differences between the primary structures of ACK-2 and ACK-1 occur in the amino- and carboxyl-terminal regions. Like ACK-1, ACK-2 binds exclusively to activated (GTP-bound) Cdc42 and does not bind to its closest homologs, e.g. activated Rac. ACK-2 could not be activated by addition of glutathione S-transferase (GST)-Cdc42(Q61L), a GTPase-defective mutant, or by GTPgammaS-loaded GST-Cdc42 in in vitro kinase assays. However, ACK-2 was activated when cotransfected with wild type Cdc42 or Cdc42(Q61L) and stably associated with Cdc42(Q61L) in vivo, indicating that ACK-2 interacts with active Cdc42 in cells. Furthermore, the tyrosine kinase activity of ACK-2 was stimulated both by epidermal growth factor and bradykinin, suggesting that ACK-2 may play a role in the signaling actions of both receptor tyrosine kinases or heterotrimeric G-protein-coupled receptors.

Amino Acid Sequence↗