Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 505 records · Page 28Linked to original sources

PubMed1996

Immunological response to the Brucella abortus GroEL homolog.

Western blot (immunoblot) analysis of sera from cattle vaccinated with Brucella abortus S19 exhibit an elevated serologic response to Hsp62, the GroEL homolog (BaGroEL). Serologic screening of individual cows vaccinated with B. abortus S19 revealed no correlation between the immune response to BaGroEL and protection against a challenge with virulent organisms. The humoral immune response to BaGroEL was restricted to a region of the mature protein which mapped to amino acids 317 to 355 and may represent a useful diagnostic tool for monitoring exposure to B. abortus. Immunity to a challenge with virulent B. abortus S2308 was not observed in the BaGroEL vaccinated mouse model.

Animals↗

PubMed1996

The amino-terminal domains of Epstein-Barr virus nuclear proteins 3A, 3B, and 3C interact with RBPJ(kappa).

The ability of Epstein-Barr virus (EBV) latent infection nuclear protein EBNA3C to activate transcription of two EBNA2-responsive genes and to inhibit EBNA2 activation of transcription in transient-transfection assays appears to be due to its ability to interact with RBPJkappa, a cell protein that links EBNA2 to its response elements. We now show that EBNA3A and EBNA3B expressed in non-EBV-infected Burkitt tumor lymphoblasts are similar to EBNA3C in binding to glutathione S-transferase-RBPJkappa in vitro and in coimmunoprecipitating from cell lysates with antibody to RBPJkappa. EBNA3A and EBNA3B can also inhibit the interaction of RBPJkappa with cognate DNA in vitro. Although EBNA3 open reading frames are each close to 1,000 codons long, EBNA3A amino acids 1 to 138, EBNA3B amino acids 1 to 311, and EBNA3C amino acids 1 to 183 are sufficient for RBPJkappa interaction, while EBNA3B amino acids I to 109 have less or no binding. The RBPJkappa interacting domains overlap with the most highly conserved domain (amino acids 90 to 320) among the EBNA3 proteins. Thus, the EBNA3 gene family appears to have evolved to differentially regulate promoters with RBPJkappa binding sites. EBNA2, EBNA3A, and EBNA3C are important in EBV transformation of primary human B lymphocytes. Their interaction with RBPJkappa links EBV transformation to the notch signaling pathway and the effects of activated notch in T-cell leukemogenesis.

Antigens, Viral↗

PubMed1996

Analysis of wild-type and mutant p21WAF-1 gene activities.

The p21WAF-1 gene is positively regulated by the wild-type p53 protein. p21WAF-1 has been shown to interact with several cyclin-dependent kinase complexes and block the activity of G1 cyclin-dependent kinases (cdks). Mutational analysis with the p21WAF-1 gene localized a site, at amino acid residues 21 and 24 in the amino terminus of the protein, for p21WAF-1 binding to cyclins D and E. This region of the protein is conserved (residues 21 to 26) in other p21WAF-1 family members, p27kip-1 and p57kip-2. The same p21WAF-121,24 mutant also fails to bind to cyclin D1-cdk 4 or cyclin E-cdk 2 complexes in vitro, suggesting that amino acid residues 21 and 24 are important for p21WAF-1-cdk-cyclin trimeric complex interactions. The p21WAF-1 wild-type protein will suppress tumor cell growth in culture while p21WAF-1 mutant proteins with defects in residues 21 and 24 fail to suppress tumor cell growth. The overexpression of cyclin D or E in these cells will partially overcome the growth suppression of wild-type p21WAF-1 protein in cells. These results provide evidence that p21WAF-1 acts through cyclin D1-cdk4 and cyclin E-cdk2 complexes in vivo to induce the growth suppression. The p21WAF-1 binding sites for cyclins (residues 21 to 26), cdk2 (residues 49 to 71), and proliferating-cell nuclear antigen (residues 124 to 164) have all been mapped to discrete sites on the protein.

Amino Acid Sequence↗

PubMed1996

mdm-2 inhibits the G1 arrest and apoptosis functions of the p53 tumor suppressor protein.

The mdm-2 gene encodes a 90-kDa polypeptide that binds specifically to the p53 tumor suppressor protein. This physical interaction results in the inhibition of the transcriptional functions of p53 (J. Chen, J. Lin, and A. J. Levine, Mol. Med. 1:142-152, 1995, and J. Momand, G. P. Zambetti, D. C. Olson, D. George, and A. J. Levine, Cell 69:1237-1245, 1992). Experiments are described that demonstrate the ability of mdm-2 to abrogate both the p53-mediated cell cycle arrest and the apoptosis functions. In addition, the results presented here suggest that mdm-2 binding to p53 and the resultant inhibition of p53 transcription functions are critical for reversing p53-mediated cell cycle arrest. The N-terminal half or domain of the mdm-2 protein is sufficient to regulate these biological activities of p53, consistent with the possibility that the highly conserved central acidic region and the C-terminal putative zinc fingers of mdm-2 may encode other functions.

3T3 Cells↗

PubMed1996

Cyclical strain increases monocyte chemotactic protein-1 secretion in human endothelial cells.

The effects of mechanical strain on monocyte chemotactic protein-1 (MCP-1) secretion were examined on human endothelial cells (ECs) grown on a flexible membrane base. MCP-1 release into culture medium from strained ECs was demonstrated to be time and strain dose dependent. Northern blot analysis demonstrated a mainly serum-independent 1.8-fold induction of MCP-1 mRNA levels in ECs strained at 15 kPa compared with unstrained controls. ECs treated with actinomycin D abolished this strain-induced expression. Strained ECs at the periphery of wells showed higher MCP-1 gene expression than ECs at the center. Pretreatment of ECs with either cytochalasin D or phalloidin did not abolish strain-induced gene expression. ECs pretreated with stretch-activated ion channel blocker gadolinium or with ryanodine to deplete intracellular stored Ca2+ strongly inhibited the strain-induced MCP-1 levels. We conclude that 1) cyclical strain can modulate the secretion of MCP-1 in a dose-dependent manner, 2) strain-induced MCP-1 production is mediated by increasing MCP-1 mRNA levels via transcription, 3) cytoskeletal rearrangement is not essential for this strain-induced MCP-1 expression, and 4) both Ca2+ influx via stretch-activated ion channels and intracellular Ca2+ release contribute to the strain-induced effect. Such strain-induced MCP-1 secretion might contribute to the trapping of monocytes in the subendothelial space to initiate atherogenesis.

Blotting, Northern↗

PubMed1996

Effect of N-methyl-D-aspartate-receptor blockade on hypoxic ventilatory response in unanesthetized piglets.

The central excitatory amino acid (EAA) neurotransmitter glutamate has been shown to mediate the ventilatory response to hypoxia through N-methyl-D-aspartate (NMDA) receptors in anesthetized adult animals. To determine the role of the EAA glutamate in the neonatal ventilatory response to hypoxia, 19 unanesthetized chronically instrumented piglets were studied. Minute ventilation (VE), oxygen consumption (VO2), arterial blood pressure (ABP), heart rate (HR), and blood gases were measured in room air (RA) and after 1, 5, and 10 min of hypoxia (inspired oxygen fraction = 0.10) before and after an infusion of saline or CGS-19755, a competitive NMDA-receptor blocker (10 mg/kg i.v.). Nine control piglets [age 6 +/- 1 (SD) days; weight 2.02 +/- 0.40 kg] and 10 CGS-19755-treated animals (age 6 +/- 1 days; weight 1.90 +/- 0.66 kg) were studied during quiet sleep and in a thermoneutral environment. There was a marked decrease in the VE response to hypoxia after the administration of CGS-19755. The ventilatory response to hypoxia was not modified by saline infusion. Changes in ABP and arterial PO2 during hypoxia were similar between groups, whereas the decrease in arterial PCO2 was significantly less after CGS-19755 administration. The increase in HR with hypoxia was eliminated by the NMDA-receptor blocker administration. VO2 decreased with hypoxia in both groups, but this decrease was more marked after the NMDA-receptor blockade. These results suggest that the central EAA glutamate mediates, at least in part, the hypoxic hyperventilation in unanesthetized newborn piglets.

Animals↗

PubMed1996

Effect of lipoxygenase inhibition on mucous glycoprotein secretion from chinchilla middle ear epithelial cells in vitro.

Lipoxygenase is an enzyme that metabolizes arachidonic acid down to leukotrienes. Recent studies have shown that the enzyme is implicated in mucous glycoprotein (MGP) secretion stimulated by inflammatory mediators in the airways, suggesting its possible role in secretion of MGP from middle ear epithelial cells. To investigate a correlation between MGP secretion and the arachidonic acid metabolites, we examined the effects of nordihydroguaretic acid (NDGA, both a cyclooxygenase and lipoxygenase inhibitor), low-dose indomethacin (an inhibitor of cyclooxygenase), and A63162 (an inhibitor of lipoxygenase) on MGP secretion in cultured chinchilla middle ear epithelial cells. It was found that lipoxygenase inhibition led to reduction of MGP secretion from cultured chinchilla middle ear epithelial cells, while cyclooxygenase inhibition did not. Both cyclooxygenase and lipoxygenase inhibition resulted in profound blockage of MGP secretion in baseline and platelet activating factor-stimulated MGP secretion. It was concluded, therefore, that MGP secretion was linked to arachidonic acid metabolites, especially lipoxygenase products.

Acetamides↗

PubMed1996

Image reconstruction with acoustic measurement using distorted Born iteration method.

The distorted Born iterative method (DBIM) is applied to solve electromagnetics and ultrasonics inverse scattering problems. First, we use the DBIM to process the data, which are the scattered fields from two-dimensional cylinders with arbitrary cross section. From this simulation, we confirmed that the first-order Born approximation can be applied to larger objects as long as the phase change of a wave passing through the object due to its presence is smaller than a limit. Then we applied DBIM to process the ultrasonic measurement data. Images for a balloon and an egg that are immersed in water have been reconstructed and compared with those from the first-order diffraction tomography (DT).

Humans↗

PubMed1996

The design and preliminary evaluation of a home electrocardiography and blood pressure monitoring network.

A home electrocardiography (ECG) and blood pressure (BP) monitoring network was established in Beijing. The network consisted of three parts: (1) the home ECG and BP monitoring devices; (2) the monitoring centre at the hospital; and (3) the data communication network, for which we chose the public telephone network. The system was tested in our university hospital for two months with 30 patients and six normal volunteers. A preliminary evaluation by the users indicated that the system was acceptable in terms of its efficiency and effectiveness. This paper describes the system design, the preliminary testing procedure, and results.

Adult↗

PubMed1996

Pharmacokinetics and molecular detoxication.

This paper presents a comprehensive overview of the pharmacokinetic parameters used from in vivo and in vitro studies that are important in order to understand the major conceptual approaches of toxicokinetics and the disposition of environmental chemicals. In vitro biochemical information concerning the detoxication of environmental chemicals is also presented. The discussion leads to a more complete appreciation for the use of in vitro measurements for in vivo correlations. The concept of interspecies scaling in the interpolation and extrapolation of fundamental biochemical metabolic processes is illustrated with a number of examples. Additional examples of in vitro-in vivo correlations are presented in the evaluation of the impact of chemical exposure to humans. Finally, several important metabolic detoxication enzymes are presented, including the mammalian microsomal cytochrome P450 and flavin-containing monooxygenases as well as carboxylesterases and glucuronosyltransferases, to provide insight into the processes of chemical detoxication in mammalian tissue and blood. Because interspecies scaling and the pharmacokinetics of chemical disposition have already shown their usefulness in understanding some examples of chemical disposition, our summary focuses on showing the usefulness of the pharmacokinetic equations and providing confidence in using the approach for in vitro-in vivo correlations. Ultimately, the presentation may provide the reader with a conceptual framework for future evaluation of the human health risks associated with environmental toxicants.

Animals↗

PubMed1996

Congenital or idiopathic hepatic vascular malformations: CT findings.

OBJECTIVE: Five CT studies in three patients with congenital or idiopathic hepatic vascular malformations were reviewed. CONCLUSION: Consistent findings included direct visualization of the abnormal vessels, hepatomegaly, and changes of fibrosis. Dual-phase helical CT in two patients also revealed arteriovenous shunting. One patient had growth of the malformation over 7 years.

Adult↗

PubMed1996

Effects of platelet-activating factor (PAF) receptor blockage on mucous glycoprotein secretion in cultured chinchilla middle ear epithelium.

Platelet-activating factor (PAF) is a naturally occurring phospholipid that acts as a pleiotropic mediator of inflammation via specific membrane receptors. It has been demonstrated in recent years that PAF is a strong secretagogue of mucous glycoprotein (MGP) in airways and middle ear epithelium. MGP secretion accompanies otitis media with effusion (OME) and prolongs the course of this disease by increasing the viscoelasticity of the fluid. It is important, therefore, to inhibit the pathological secretion of MGP in the treatment of otitis media. In the current study, we investigated the effects of PAF receptor inhibitor WEB 2170 BS on in vitro MGP secretion. At concentrations of 100 mu M, PAF significantly stimulated MGP secretion. WEB 2170 BS significantly inhibited this PAF-simulated MGP secretion at concentrations of 2000 mu M. The action of WEB 2170 BS was concentration-dependent. However, it did not affect MGP secretion stimulated by IL-1beta, suggesting that WEB 2170 BS inhibits PAF-stimulated MGP secretion, specifically. It was noted that WEB 2170 BS did not completely eliminate MGP secretion induced by PAF even though a high concentration was used. The fact that WEB 2170 BS alone does not exhibit an inhibitory or stimulatory effect on the secretion of MGP suggests that WEB 2170 BS competitively binds to PAF receptors and possesses less affinity to PAF receptors than PAF.

Animals↗

PubMed1996

[Observation of the invasion of retinoblastoma cells to ocular tissues in vitro].

PURPOSE: To study the invasion of retinoblastoma cells to ocular tissues. METHODS: The SO-Rb50 cells of retinoblastoma and various ocular tissue cells were co-cultured. The morphological change of the SO-Rb50 cells adherent to ocular tissue cells was observed. RESULTS: SO-Rb50 cells can adhere to the various ocular tissues. The adherent ability of SO-Rb50 cell to different ocular tissue cells was different. Tumor cells could be adhesive to keratocyte, scleral fibrocyte, the fibrocyte and the melanocyte of iris and choroid, the epithelial cells of lens, and the astrocyte of optic nerve and grow, but can not be adhesive to the corneal epithelial cell and retinal pigment epithelial cell. CONCLUSIONS: We consider that the interactions of tumor cells with host cells, as with extracellular matrix, also play an important role in the selective growth of organ and tissue of tumor cell metastasis. Retinoblastoma cells can not adhere to retinal pigment epithelial cell, which may serve as a barrier to obstruct the invasion of tumor cell to the choroid. Being adherent to the glial cells of optic nerve, tumor cells grow in flat and the shape of tumor cell changes, which may be the cause of tumor cell migrate rapidly and grow in the brain while the optic nerve was invaded by tumor cells.

Adult↗

PubMed1996

Selective blockade of cholecystokinin type B receptors with L-365,260 does not impair gallbladder contraction in normal humans.

OBJECTIVES: To evaluate the effect of selective blockade of type B cholecystokinin receptors on gall bladder contraction in normal humans and to compare methods for quantitative analysis of gall bladder contraction. METHODS: L-365,260, a novel, nonpeptide cholecystokinin antagonist shown to be selective for type B cholecystokinin receptors, was administered every 6 h over a 5-7 day period. Plasma levels of L-365,260 were determined by high pressure liquid chromatography. Gallbladder contraction after a standardized fatty meal was measured by ultrasonography, and results were calculated by ellipsoid or sum of cylinders methods. RESULTS: L-365,260 levels were comparable to levels in earlier studies demonstrating inhibition of pentagastrin-stimulated acid secretion in normal subjects and blockade of anxiogenic effects of cholecystokinin injections in patients with panic disorder. Regardless of the method used for estimating gallbladder size, none of the L-365,260 doses studied inhibited gallbladder contraction. Gallbladder size was most consistently estimated by the ellipsoid method using measurements normalized to individual values for minimum and maximum gallbladder dimensions. CONCLUSIONS: Multiple oral doses of L-365,260 do not alter ultrasonographically assessed gallbladder contraction at doses shown to be clinically effective in earlier studies. Despite being more difficult to implement, the sum of cylinders method for estimating gall bladder size offers no advantage over the ellipsoid method.

Adult↗

PubMed1996

Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials.

OBJECTIVE: To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model. DESIGN: Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically. ANIMALS: 6 mixed-breed dogs weighing 16 to 20 kg. PROCEDURE: 72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred. RESULTS: Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month. CONCLUSION: In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut. CLINICAL RELEVANCE: Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted.

Abdomen↗

PubMed1996

Identification and characterization of yeast mutants that overcome an experimentally introduced block to splicing at the 3' splice site.

An experimentally introduced secondary structure in exon 2 adjacent to the 3' splice site of a yeast ACT-Escherichia coli lacZ fusion gene abolishes splicing in vivo and inhibits beta-galactosidase production. We have devised a genetic screen to isolate both cis and trans-acting mutants that restore beta-galactosidase activity. Two cis-acting mutants potentially destabilize the stem in the region close to the 3' splice site. One trans-acting mutant, designated rss1-1, partially restores beta-galactosidase activity by both increasing the splicing efficiency and stabilizing the precursor and lariat intermediate. The trans-acting suppression activity of rss1-1 is specific for a particular structure because another artificially introduced secondary structure, which also blocks splicing, is not suppressed by this mutant allele. We have cloned the gene encoding the trans-acting mutant protein. The RSS1 gene is located on Saccharomyces cerevisiae chromosome V and is a single copy, essential gene. The predicted RSS1 protein has marked similarity to members of the putative ATP-dependent RNA helicase family. At the nonpermissive temperature, the rss1-1 mutant allele decreases the steady-state levels of several endogenous messenger RNAs and increases the ratio of pre-mRNA to mRNA of specific messages. RSS1 is likely to play an interesting role in RNA processing.

Adenosine Triphosphate↗

PubMed1996

Structural determinants of cobrotoxin for binding to an enzyme-linked-immunoassay plate.

In order to assess the manner in which the structural state of a protein affects the results of an ELISA, the antigenic reactivities of cobrotoxin and reduced and S-carboxymethylated (RCM-) cobrotoxin with anti-RCM-cobrotoxin antibodies were studied. The results of competitive enzyme-linked immunoassay showed that the affinity of RCM-cobrotoxin for anti-RCM-cobrotoxin antibodies was higher than that of cobrotoxin. However, the cobrotoxin-coated wells had a greater reactivity towards anti-RCM-cobrotoxin antibodies than against RCM-cobrotoxin-coated wells. The lower reactivity observed with RCM-cobrotoxin-coated plates could be improved by adding 0.01% glutaraldehyde during the coating procedure. Studies on the antigenic structures of RCM-cobrotoxin showed that it contained an immunodominant epitope at residues 22-38. Moreover, the N-terminal and C-terminal regions of RCM-cobrotoxin encompassed other antigenic determinants which exhibited low reactivities towards anti-RCM-cobrotoxin antibodies. After removal of the antibodies against residues 22-38 of cobrotoxin from anti-RCM-cobrotoxin antibodies by passage through an affinity column, the remaining antibodies exhibited a similar reactivity towards cobrotoxin and RCM-cobrotoxin. The antibodies against residues 22-38 retained a little reactivity with the RCM-cobrotoxin-coated wells. These results suggest that the structural determinants of cobrotoxin and RCM-cobrotoxin for binding to the microtitre plates differ. Unlike RCM-cobrotoxin, the loop II structure of cobrotoxin encompassing residues 22-38 is not exclusively involved in the binding of cobrotoxin to microtitre plates.

Antibodies↗

PubMed1996

Detection of PML-RAR alpha in patients with APL during follow-up period.

OBJECTIVE: To evaluate the significance of PML-RAR alpha transcripts in patients with acute promyelocytic leukemia (APL) during remission period and to follow up the patients through monitoring aberrant gene expression. PATIENTS AND METHODS: This study included 17 patients with APL (5 females and 12 males). Another 19 APL patients during relapse served as control. RNA extraction was obtained through the single-step method. By means of reverse transcriptase polymerase chain reaction (PCR), the PML-RAR alpha was detected in the sample mRNA. RESULTS: Nine out of 10 patients with complete remission (CR) duration shorter than 3 years were positive. Four cases became negative and three remained positive among 7 cases in a long remission of over 3 years. The difference of the positive rate of PML-RAR alpha transcripts between the 2 groups was significant (P < 0.05). Four among 12 positive cases relapsed. No evidence of relapse was present in the 5 negative patients after 9.6 +/- 3.9-month follow-up. Further treatment was therefore given to the 4 positive patients whose treatment was already ceased at that time. By this management they were all in CR during the following 10-month observation. CONCLUSIONS: RT-PCR detection for PML-RAR alpha transcripts was useful in monitoring MRD and guiding further treatment to obtain a long remission. Persistently positive transcripts were closely associated with the relapse.

Adolescent↗