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Biomedical subjects

L Wang

Publications and source records attributed to L Wang.

At least 1,171 records · Page 65Linked to original sources
PubMed1999

[The development of an intelligent vision testing instrument].

The paper introduces an intelligent vision testing instrument, which works on automatic method or manual method. The examinee inputs his or her judgement about the direction of the letter "E" with remote control. The system examines and judges the examinee's judgement, and then prints the testing report. The vision testing range is from logarithm vision 3.0 to 5.3. The distance between examinee and optometer can be measured automatically by the system with infrared and ultrasonic testing functions and a good accuracy.

Diagnosis, Computer-Assisted↗
PubMed1999

[The method of wavelet transformation used for extracting the characteristic of the exercise ECG].

This article introduces the basic rationale of wavelet transformation and the algorithm of typical dyadic wavelet transformation with mother wavelet of the first derivative of a Gaussian smoothing function, this wavelet transformation is used to recognize the characteristic parameters of the exercise ECG, it is concluded that this method make significant effects on restricting base line drifting and lessening noisy component in the exercise ECG, it provides a new way to do further research on characteristic recognition of the exercise ECG in the exercise test.

Algorithms↗
PubMed1999

[Differences in furosemide-induced changes of summating potential and endocochlear potential in guinea pigs].

OBJECTIVE: To investigate the physiological properties of summating potential (SP) and to compare the different changes between SP and endocochlear potential (EP) induced by Furosemide in guinea pigs. METHODS: SP in response to clicks with alternative polarities at 105 dB peSPL was recorded from a electrode in the facial nerve canal. EP was measured with a glass microelectrode in the basal turn of the cochlea. SP and EP were observed simultaneously and continuously after injection of Furosemide or the solution of Furosemide-bovine serum albumin injected into the jugular vein of the animal. RESULTS: Before furosemide application, only SP could be recorded with small or without +SP. After furosemide injection, EP declined dramatically followed by reduction of the -SP which quickly vanished, while +SP appeared or the amplitude increased. When EP recovered to a certain level, +SP disappeared or dramatically decreased and then -SP reappeared. The amplitude of -SP increased progressively with EP recovery. Both -SP and EP recovered to the pre-injected level in 60 min after the furosemide application. CONCLUSION: The results suggest that Furosemide induced distinct changes of -SP and +SP, the two components of SP. The changes of -SP amplitude was consistent with that of the EP value, while the changes of +SP amplitude were contrary to that of the EP value.

Animals↗
PubMed1999

[Study on the association between squamous cell carcinoma of larynx and HPV subgene by PCR].

OBJECTIVE: To measure the human papilloma virus(HPV) HPV-E1 in squamous cell carcinoma of larynx. METHODS: Polymerase chain reaction(PCR) was used to detect the HPV subgene in 25 specimens of laryngeal carcinoma and 6 normal larynges. RESULTS: Positive expression of HPV-E1 was detected in 17 of 25 cases(68%) with squamous cell carcinoma and all the recurrent cases. However, there was no positive expression of HPV-E1 in the normal larynges (P < 0.01). The expression rate was not significantly different among the histological grad groups. CONCLUSION: HPV-E1 infection was found in laryngeal carcinoma but not related to its histologic grading.

Carcinoma, Squamous Cell↗
PubMed1999

[Research into the mechanism of fragile sealing on the composition packet].

The research into the fragility of the sealing on two composition films for ham packages by using Fourier infrared spectrometer, DTG and melting index detector is reported. The research shows that the cause of the fragility of the sealing is the differences in the materials and their softening points and melting indexes between the inner film and the outer film. The inner film is made of adhesive polypropylene, whose softening point is 148.8 degrees C and melting index (MI) is 6.049 g/10 min. However, the outer film is made of polyamide 610, whose softening point is 221 degrees C, 72.2 degrees C higher than that of inner film, and melting index is 3.09 g/10 min, almost half of the MI of inner film. The mechanism of the fragile sealing on the composition packet is also discussed.

Polypropylenes↗
PubMed1999

[A comparison of Fe, Zn, Cu, Cr, Cd and Pb concentration in serum determined by ICP-AES using different sample preparation procedures].

Fe, Zn, Cu, Cr, Cd and Pb concentrations in serum of 21 arteriosclerosis (AS) and 18 healthy control (CK) were determined by ICP-AES, and sample solution was prepared using acid digestion (Dig.) and acid dilution (Dil.) procedure. Serum total Fe, Zn and Cr were significantly higher using Dig. than that using Dil. Serum Cu and Pb were of no significant differences using the both procedures. Serum Cd was significantly lower using Dig. than that using Dil. The results of Fe, Cu, Zn and Cr were positively correlated between Dig. and Dil., but those of Pb and Cd were of no significant correlation. Six elements concentrations in serum determined were significantly different between AS and CK using Dig. The digestion procedure was recommended for serum trace elements analysis using ICP-AES.

Case-Control Studies↗
PubMed1999

[Columinescence effect of dysprosium-lanthanum-tiron system and its applicaton].

The columinescence effect of dysprosium-Tiron system by lanthanum was discovered and the characteristics of fluorescence spectra of the system were studied. The effect of the experimental conditions on the fluorescence intensity was defined. By adding suitable amount of lanthanum to dysprosium-Tiron system, the fluorescence intensity can be enhanced by about 40 times. The fluorescence intensity is a linear function of the concentration of dysprosium in the range of 5.0 x 10(-8)-9.0 x 10(-6) mol/L. The detection limit is 1.0 x 10(-10) mol/L. Standard addition method is used for the determination of dysprosium in synthetic rare earth sample with satisfactory results.

English Abstract↗
PubMed1999

[Study on luminescence of the serial new ternary or tetradic complexes complexes of Eu (III) with beta-diketone].

The UV absorption, fluorescence, unstable spectra and quantum yields of five ternary or tetradic complexes of Eu (III) with beta-diketone (dibenzoyl methane, thenoyltrifluoroacetone), acrylic acid and other ligands were reported. The influences of the first and second ligands on absorption and luminescence spectra were found. The lifetimes and the processes of energy transfer of Eu3+ from 5D1 to 5D0 in complex solutions were measured. It was found that the lifetimes of Eu3+ complexes with TTA are approximate to each other and larger than those of complexes with DBM.

English Abstract↗
PubMed1999

Frequent deletions within FRA7G at 7q31.2 in invasive epithelial ovarian cancer.

We previously showed that FRA7G, an aphidicolin-inducible common fragile site at 7q31.2, colocalized with the common region of loss of heterozygosity (LOH) in a number of different tumors. Based on the sequence analysis of 150 Kb in the FRA7G region, we identified four new polymorphic microsatellite markers. In this article, we have used these four microsatellite markers and eight additional markers from 7q22-32 to analyze the breakage and loss of the region surrounding FRA7G in 49 invasive epithelial ovarian cancers and three borderline ovarian tumors. No allelic loss was detected in the ovarian tumors of borderline malignancy, but 71% (35/49) of the invasive tumors showed LOH at one or more loci in the region analyzed. Of the 12 markers analyzed, most of the markers exhibiting a high frequency of LOH were within FRA7G, and the highest frequency of LOH was seen with the new marker 7G14 (37%, 15/41). Breakpoint analysis in tumors with LOH demonstrated that the frequent loss of DNA sequences seen within the FRA7G region was due to frequent small interstitial deletions and not a result of loss of the whole fragile site region. These findings indicate that FRA7G does play a role in the breakage and loss of 7q sequences in invasive ovarian cancer. In addition, the newly identified markers enable us to further delineate a smallest common region of loss in invasive ovarian tumors to a 150-Kb region flanked by markers D7S486 and 7G14.

Carcinoma↗
PubMed1998

Molecular cloning of the human HAND2 gene.

We have cloned and characterized the coding sequence of the human HAND2 basic helix-loop-helix transcription factor. The amino acid sequence includes an amino-terminal polyalanine repeat which is precisely conserved in the rat HAND2 gene. Northern analysis indicates that the HAND2 transcript is 2.3 kb in length and strongly expressed in the human heart.

Amino Acid Sequence↗
PubMed1998

Insulin stimulates sequestration of beta-adrenergic receptors and enhanced association of beta-adrenergic receptors with Grb2 via tyrosine 350.

G-protein-linked receptors, such as the beta2-adrenergic receptor, are substrates for growth factor receptors with intrinsic tyrosine kinase activity (Karoor, V., Baltensperger, K., Paul, H., Czech, M. P., and Malbon C. C. (1995) J. Biol. Chem. 270, 25305-25308). In the present work, the counter-regulatory action of insulin on catecholamine action is shown to stimulate enhanced sequestration of beta2-adrenergic receptors in either DDT1MF-2 smooth muscle cells or Chinese hamster ovary cells stably expressing beta2-adrenergic receptors. Both insulin and insulin-like growth factor-1 stimulate internalization of beta-adrenergic receptors, contributing to the counter-regulatory effects of these growth factors on catecholamine action. In combination with beta-adrenergic agonists, insulin stimulates internalization of 50-60% of the complement of beta-adrenergic receptors. Insulin administration in vitro and in vivo stimulates phosphorylation of Tyr-350 of the beta-adrenergic receptor, creating an Src homology 2 domain available for binding of the adaptor molecule Grb2. The association of Grb2 with beta-adrenergic receptors was established using antibodies to Grb2 as well as a Grb2-glutathione S-transferase fusion protein. Insulin treatment of cells provokes binding of Grb2 to beta2-adrenergic receptors. Insulin also stimulates association of phosphatidylinositol 3-kinase and dynamin, via the Src homology 3 domain of Grb2. Both these interactions as well as internalization of the beta-adrenergic receptor are shown to be enhanced by insulin, beta-agonist, or both. The Tyr-350 --> Phe mutant form of the beta2-adrenergic receptor, lacking the site for tyrosine phosphorylation, fails to bind Grb2 in response to insulin, fails to display internalization of beta2-adrenergic receptor in response to insulin, and is no longer subject to the counter-regulatory effects of insulin on cyclic AMP accumulation. These data are the first to demonstrate the ability of a growth factor insulin to counter-regulate G-protein-linked receptor, the beta-adrenergic receptor, via a new mechanism, i.e. internalization.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Monolayer Behavior of Tetraphenylporphyrin Derivatives Containing Four Fluorocarbon Chains and Optical Properties of Their Monolayer Assemblies.

For tetraphenylporphyrin derivatives substituted with four fluorocarbon chains (TFPP), monolayers on the water surface were studied with the Brewster angle microscope together with pressure-area curves. It was found that heterogeneous aggregated structures of the monolayers were dependent upon the chain length of fluorocarbons, the metal-free or Mn-TFPP, and the periods after spreading. Polarized UV-visible spectra for the monolayer assemblies indicated that the porphyrin rings in the films were tilted on the average, but had a tendency to adopt an orientation more parallel to the water surface as the chain length of the fluorocarbon increased. The third-order nonlinear optical susceptibility for the monolayer assembly of TFPP with the shorter chains was found to be 7.0 x 10(-13) esu, and those of Mn-TFPP were enlarged. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Rat brain capillary thrombomodulin: structure and function.

The anticoagulant transmembrane glycoprotein thrombomodulin (TM) is expressed at the luminal surface of vascular endothelial cells. Recently, we showed that TM antigen and TM mRNA are expressed in brain microvessels in several species and that brain capillaries have the capability to activate protein C. The activation of protein C in brain microcirculation was greatly impaired by major stroke risk factors in rats due to downregulation of TM. In this study, a partial sequence of TM was determined from TM mRNA from brain capillaries examined in brain capillaries of the rat, a species that provides a useful model to investigate stroke mechanisms in relation to brain hemostasis. The predicted deduced amino acid sequences for rat TM were compared with other TM sequences. Particularly high homology (77-100%) among functional domains of the protein, i.e., the epidermal growth factor repeats (EGFRs) 1-6 and the transmembrane region, was observed between mice and rats. Somewhat less degree of homology was observed for bovine and human EGFRs 1-6, while the homology of the transmembrane region was 92-96%. All cysteine residues were conserved among the TM sequences, and specific amino acids previously suggested to be essential for activation of protein C by thrombin TM were highly conserved. We conclude that the highly conserved mRNA and protein sequences may reflect a similar anticoagulant role of TM in brain endothelial and systemic vascular endothelial cells across different species.

Amino Acid Sequence↗
PubMed1998

Crystal structure of farnesyl protein transferase complexed with a CaaX peptide and farnesyl diphosphate analogue.

The crystallographic structure of acetyl-Cys-Val-Ile-selenoMet-COOH and alpha-hydroxyfarnesylphosphonic acid (alphaHFP) complexed with rat farnesyl protein transferase (FPT) (space group P61, a = b = 174. 13 A, c = 69.71 A, alpha = beta = 90 degrees, gamma = 120 degrees, Rfactor = 21.8%, Rfree = 29.2%, 2.5 A resolution) is reported. In the ternary complex, the bound substrates are within van der Waals contact of each other and the FPT enzyme. alphaHFP binds in an extended conformation in the active-site cavity where positively charged side chains and solvent molecules interact with the phosphate moiety and aromatic side chains pack adjacent to the isoprenoid chain. The backbone of the bound CaaX peptide adopts an extended conformation, and the side chains interact with both FPT and alphaHFP. The cysteine sulfur of the bound peptide coordinates the active-site zinc. Overall, peptide binding and recognition appear to be dominated by side-chain interactions. Comparison of the structures of the ternary complex and unliganded FPT [Park, H., Boduluri, S., Moomaw, J., Casey, P., and Beese, L. (1997) Science 275, 1800-1804] shows that major rearrangements of several active site side chains occur upon substrate binding.

Alkyl and Aryl Transferases↗
PubMed1998

Tumor necrosis factor-alpha induces adhesion molecule expression through the sphingosine kinase pathway.

The signaling pathways that couple tumor necrosis factor-alpha (TNFalpha) receptors to functional, especially inflammatory, responses have remained elusive. We report here that TNFalpha induces endothelial cell activation, as measured by the expression of adhesion protein E-selectin and vascular adhesion molecule-1, through the sphingosine kinase (SKase) signaling pathway. Treatment of human umbilical vein endothelial cells with TNFalpha resulted in a rapid SKase activation and sphingosine 1-phosphate (S1P) generation. S1P, but not ceramide or sphingosine, was a potent dose-dependent stimulator of adhesion protein expression. S1P was able to mimic the effect of TNFalpha on endothelial cells leading to extracellular signal-regulated kinases and NF-kappaB activation, whereas ceramide or sphingosine was not. Furthermore, N, N-dimethylsphingosine, an inhibitor of SKase, profoundly inhibited TNFalpha-induced extracellular signal-regulated kinases and NF-kappaB activation and adhesion protein expression. Thus we demonstrate that the SKase pathway through the generation of S1P is critically involved in mediating TNFalpha-induced endothelial cell activation.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Structure and mapping of the human beta-defensin HBD-2 gene and its expression at sites of inflammation.

We cloned a second human beta-defensin gene, HBD-2, and determined its gene structure and expression in inflamed tissue sections. The entire gene spanned about 2 kb with two small exons and one intron. Radiation hybrid studies confirmed the location on chromosome 8p, were consistent with the order HNP-1, HBD-1 and HBD-2, and located HBD-2 as the most centromeric of the genes. By three-color fluorescence in situ hybridization on both free chromatin fiber mapping and interphase mapping, HBD-1, HBD-2 and HNP-1 were mapped to chromosome 8p23. HBD-1 was within 40-100kb of HNP-1, while HBD-2 was about 500-600 kb from HBD-1, with the most likely order HNP-1, HBD-1, HBD-2. The expression of HBD-2 was locally regulated by inflammation. HBD-2 mRNA was markedly increased in the epidermis surrounding inflamed regions, but not detectable in adjacent non-inflamed areas, a distribution that was confirmed at the peptide level by immunostaining with HBD-2 antibody. The HBD-2 gene is the first member of the human defensin family that is locally inducible by inflammation.

Base Sequence↗