Biomedical subjects

J D Li

Publications and source records attributed to J D Li.

At least 19 recordsLinked to original sources

PubMed2003

Ethanol-induced mitogen activated protein kinase activity mediated through protein kinase C.

The aim of this study was to determine the pathway(s) by which ethanol activates mitogen-activated protein kinase (MAPK) signaling and to determine the role of Ca2+ in the signaling process. MAPK signaling was determined by assessing MAPK activity, measuring phosphorylated extracellular signaling-regulated kinase (pp 44 ERK-1 and pp 42 ERK-2) expression and ERK activity by measuring ERK-2-dependent phosphorylation of a synthetic peptide as a MAPK substrate in rat vascular smooth muscle cells. Ethanol activated extracellular signal-regulated kinase expression (ERK 1 and 2) could be observed when vascular smooth muscle cells (VSMCs) were stimulated for 5 min or less, but was inhibited when cells are treated for 10 min or more with 1-16 mM of ethanol. Maximum ethanol-induced MAPK activity was observed within 5 min with 4 or 8 mM. Ethanol stimulated MAPK activity was blocked by the protein kinase C (PKC) inhibitor (GF109203X) and epidermal growth factor (EGF) receptor antagonist (PD153035) by 41 +/- 24 and 34 +/- 12.3%, respectively. The calcium channel blocker, diltiazem and the chelating agent, BAPTA, reduced the activation of MAPK activity by ethanol, significantly. The data demonstrate that ethanol-stimulated MAPK expression is mediated partially through both the EGF-receptor and PKC intermediates and that activation through the PKC intermediate is calcium-dependent.

Animals↗

PubMed2001

Capillary electrophoresis-electrospray mass spectrometry for the characterization of high-mannose-type N-glycosylation and differential oxidation in glycoproteins by charge reversal and protease/glycosidase digestion.

The characterization of high-mannose-type N-glycosylation by capillary electrophoresis-electrospray mass spectrometry (CE-ESI MS) was described. In addition to the use of a cationic noncovalent capillary coating, strong acidic buffer, and charge reversal to increase the glycoform resolving power, N-glycosidase F (PNGase F) combined with a basic protease and alpha-mannosidase combined with an acidic protease were used to analyze the high-mannose-type N-glycosylation in ribonuclease B (RNase B) and in a novel C-type lectin from the venom of Trimeresurus stejnegeri (TSL). The structures of oligosaccharide, glycosylation sites, and glycoform distributions were determined simultaneously, and the differential oxidation of Met residues in glycopeptides obtained from TSL protease digestion was also characterized successfully by CE-MS/MS. The results showed that the oligosaccharide attached to RNase B has a structure of GlcNAc2Man5 approximately 9, and that attached to TSL has a structure of GlcNAc2Min5 approximately 8. The glycoform distributions in these glycoproteins are quite different, with the GlcNAc2Man5 type predominant in RNase B, and the GlcNAc2Man8 type, in TSL This method may be useful not only for the characterization of glycosylation sites and glycan structures, but also for the determination of the relative abundance of individual glycoforms.

Alkylation↗

PubMed2001

Activation of NF-kappa B by nontypeable Hemophilus influenzae is mediated by toll-like receptor 2-TAK1-dependent NIK-IKK alpha /beta-I kappa B alpha and MKK3/6-p38 MAP kinase signaling pathways in epithelial cells.

Nontypeable Hemophilus influenzae (NTHi) is an important human pathogen in both children and adults. In children, it causes otitis media, the most common childhood infection and the leading cause of conductive hearing loss in the United States. In adults, it causes lower respiratory tract infections in the setting of chronic obstructive pulmonary disease, the fourth leading cause of death in the United States. The molecular mechanisms underlying the pathogenesis of NTHi-induced infections remain undefined, but they may involve activation of NF-kappa B, a transcriptional activator of multiple host defense genes involved in immune and inflammatory responses. Here, we show that NTHi strongly activates NF-kappa B in human epithelial cells via two distinct signaling pathways, NF-kappa B translocation-dependent and -independent pathways. The NF-kappa B translocation-dependent pathway involves activation of NF-kappa B inducing kinase (NIK)--IKK alpha/beta complex leading to I kappa B alpha phosphorylation and degradation, whereas the NF-kappa B translocation-independent pathway involves activation of MKK3/6--p38 mitogen-activated protein (MAP) kinase pathway. Bifurcation of NTHi-induced NIK-IKK alpha/beta-I kappa B alpha and MKK3/6--p38 MAP kinase pathways may occur at transforming growth factor-beta activated kinase 1 (TAK1). Furthermore, we show that toll-like receptor 2 (TLR2) is required for NTHi-induced NF-kappa B activation. In addition, several key inflammatory mediators including IL-1 beta, IL-8, and tumor necrosis factor-alpha are up-regulated by NTHi. Finally, P6, a 16-kDa lipoprotein highly conserved in the outer membrane of all NTHi and H. influenzae type b strains, appears to also activate NF-kappa B via similar signaling pathways. Taken together, our results demonstrate that NTHi activates NF-kappa B via TLR2-TAK1-dependent NIK--IKK alpha/beta-I kappa B alpha and MKK3/6--p38 MAP kinase signaling pathways. These studies may bring new insights into molecular pathogenesis of NTHi-induced infections and open up new therapeutic targets for these diseases.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed2001

[Effects of heat stress on DA mediated PI signal transduction system in rat striatum].

Objective. To study the effects of heat stress on dopamine (DA) and related phosphatidylinositol (PI) signal transduction system members: PLA2, PI, Ca2+ in rat striatum. Method. Male Wistar rats were randomly divided into control group and heat stressed group. Heat stressed rats were placed in small hot chambers and taken out as soon as their rectal temperatures (Tr) reached the preset temperature. Then the animals were killed and their striatums were taken out. Fluorospectrophotometry, HPLC, Fura-2/AM fluoresence labelled method and acidalkaline titration were used to measure the content of DA, PI, [Ca2+]i and the enzyme activity of PLA2. Result. During heat stress, when rats' Tr reached 41.0 degrees C or higher, with increase of Tr, DA content increased continuously. When Tr = 43.0 degrees C, DA content was significantly higher than control. When Tr = 41.0 degrees C PLA2 activity was higher than control significantly, PI content of heat stressed group decreased significantly than control. [Ca2+]i increased significantly when Tr = 42.0 degrees C as compared with control. But if DA receptor2 (D2R) antagonist was given an hour before heat stress, [Ca2+]i decreased and Tr took a longer time to get to 42.0 degrees C. Conclusion. During heat stress, DA mediated PI signal transduction system was activated. The increase of [Ca 2+]i might be mediated by D2R, and D2R antagonist may improve thermotolerance.

Animals↗

PubMed2001

[System study of endangerment medicinal animals in China].

OBJECTIVE: Establishing system study of endangerment medicinal animals is essential for the protection of certain species of medicinal wild fauna. METHOD: It was analyzed and summed up according to the study and protection actuality of endangerment medicinal animal in recent years. RESULT AND CONCLUSION: It was essential to research endangerment medicinal animals for realizing modernization, industrialization, internationalization and stabilization development of Chinese Materia Medica.

Animal Use Alternatives↗

PubMed2000

Cell biology of tubotympanum in relation to pathogenesis of otitis media - a review.

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Animals↗

PubMed2000

[Treatment of ischemic necrosis of femoral head by the transfer of vascular pedicled iliac periosteum].

OBJECTIVE: To investigate the therapeutical effect of treatment of ischemic necrosis of femoral head by the transfer of vascular pedicled iliac periosteum. METHODS: From June 1983 to August 1997, 106 cases with ischemic necrosis of femoral head (II stage in 64 cases, III stage in 39 cases, IV stage in 3 cases) were treated by the transfer of vascular pedicled iliac periosteum with ascending branch of lateral femoral circumflex vessel or deep circumflex iliac vessel pedicle. RESULTS: Followed up 2 years and 4 months to 16 years, there were excellent in 54 cases, better in 38 cases, moderate in 9 cases, poor in 5 cases, and 86.8% in excellent rate according to the criterion of the therapeutical effect on the repair and reconstruction of adult ischemic necrosis of femoral head. CONCLUSION: Treating ischemic necrosis of femoral head by the transfer of vascular pedicled iliac periosteum has the advantage of constant pedicle, easily drawing materials and reliable therapeutical effect.

Adolescent↗

PubMed1998

Tumor-derived EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates collagenase transcription through MAPK p38.

EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates fibroblast metalloproteinases (MMP) 1, 2 and 3 (Kataoka et al. (1993) Cancer Res. 53, 3154-3158). Here we focus on MMP-1, showing that in lung tumors, MMP-1's cognate mRNA is strongly expressed in stromal fibroblasts adjacent to EMMPRIN-expressing tumor cells. In vitro, EMMPRIN upregulates MMP-1 mRNA expression in a concentration-dependent manner, with a peak accumulation at 24 h. The response is genistein-sensitive, suggesting it is dependent on tyrosine kinase activity. Analysis of tyrosine phosphorylation-dependent MAP kinases ERK 1/2, SAPK/JNK, and p38 showed that the activity of p38 but not that of the other 2 kinases was elevated in response to EMMPRIN. That p38 activity was required for EMMPRIN stimulation of MMP-1 was evident from results showing that the p38 inhibitor SB203580 blocked this response. This is the first available information regarding the mechanism by which tumor-associated molecules upregulate MMP synthesis in stromal fibroblasts.

Antigens, CD↗

PubMed1998

Activation of NF-kappaB via a Src-dependent Ras-MAPK-pp90rsk pathway is required for Pseudomonas aeruginosa-induced mucin overproduction in epithelial cells.

Cystic fibrosis (CF) is an autosomal recessive disorder, the most common lethal genetic disease in Caucasians. Respiratory disease is the major cause of morbidity and mortality. Indeed, 95% of CF patients die of respiratory failure. Pseudomonas aeruginosa, an opportunistic pathogen, chronically infects the lungs of over 85% of CF patients. It is ineradicable by antibiotics and responsible for airway mucus overproduction that contributes to airway obstruction and death. The molecular mechanisms underlying this pathology are unknown. Here we show that P. aeruginosa activates a c-Src-Ras-MEK1/2-MAPK-pp90rsk signaling pathway that leads to activation of nuclear factor NF-kappaB (p65/p50). Activated NF-kappaB binds to a kappaB site in the 5'-flanking region of the MUC2 gene and activates MUC2 mucin transcription. These studies bring new insight into bacterial-epithelial interactions and more specifically into the molecular pathogenesis of cystic fibrosis. Understanding these signaling and gene regulatory mechanisms opens up new therapeutic targets for cystic fibrosis.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1998

Chemokine inhibition in rat stab wound brain injury using antisense oligodeoxynucleotides.

Traumatic injury to the central nervous system (CNS) results in the breakdown of the blood-brain barrier and recruitment of hematogenous cells at the site of injury. The role of chemokines in this process has been well recognized and they have been regarded as promising targets for development of anti-inflammatory therapies. The expression of monocyte chemoattractant protein (MCP-1), in particular, has been closely linked to macrophage infiltration following trauma in rat brain. In this study we determined whether inhibition of MCP-1 following stab wound injury would reduce macrophage infiltration. Stab wound injured Sprague-Dawley rats were infused with MCP-1 sense or antisense oligonucleotides using an Alzet miniosmotic pump (1 microl/h for 3 days). Three days following injury, widespread gliosis was observed in both groups of rats as judged by glial fibrillary acidic protein (GFAP) immunoreactivity. Immunohistochemistry showed significantly less staining for MCP-1 in antisense treated animals. In addition, the number of macrophages were reduced by 30% in the antisense compared to the sense treated animals (P < 0.05). These results demonstrate that modulation of MCP-1 expression in stab wound injury directly affects monocytic infiltration and provide a basis for MCP-1 inhibition as a therapeutic strategy for controlling inflammatory events of traumatic brain injury.

Animals↗

PubMed1998

Mucin gene (MUC 2 and MUC 5AC) upregulation by Gram-positive and Gram-negative bacteria.

Bacterial infection of the lung is associated with mucin overproduction. In partial explanation of this phenomenon, we recently reported that supernatant from the Gram-negative organism Pseudomonas (P.) aeruginosa contained an activity that upregulated transcription of the MUC 2 mucin gene [J.-D. Li, A. Dohrman, M. Gallup, S. Miyata, J. Gum, Y. Kim, J. Nadel, A. Prince, C. Basbaum, Transcriptional activation of mucin by P. aeruginosa lipopolysaccharide in the pathogenesis of cystic fibrosis lung disease, Proc. Natl. Acad. Sci. U.S.A., 94 (1997) 967-972]. The purpose of the present study was to determine whether mucin genes other than MUC 2 are so regulated and whether Gram-positive organisms also contain mucin stimulatory activity. Results from in situ hybridization and RNase protection assays showed that P. aeruginosa upregulates MUC 5AC as well as MUC 2 in both bronchial explants and cultured airway epithelial cells. The upregulation of both genes by P. aeruginosa can be mimicked by lipopolysaccharide (LPS) and can be blocked by the tyrosine kinase inhibitor genistein. In addition, both genes are upregulated by a variety of Gram-positive as well as Gram-negative organisms showing the same rank order of potency. These data indicate the existence of a general mechanism by which epithelial cells respond to the presence of bacteria by increasing mucin synthesis.

Bronchi↗

PubMed1997

Sp1 protein contributes to airway-specific rat MUC 2 mucin gene transcription.

We have shown increases in the abundance of airway mucin mRNA during the pathogenesis of chronic obstructive pulmonary disease in rat models (Jany et al., 1991) and now seek to determine the underlying mechanisms. As transcriptional modulation may be involved, we provide here a functional analysis of the 5' flanking region of a rat mucin gene (MUC 2). Using deletion mutants to bp -859, we constructed expression cassettes in CAT vectors and transfected them into two MUC 2-expressing cell lines, SPOC 1, a rat airway epithelial cell line and IEC-6, a rat intestinal epithelial cell line, and into one MUC 2 non-expressing cell line, FR, a rat skin fibroblast cell line. Results indicated that nucleotides -59 to -40 mediated high level expression in SPOC 1, but not in the other cells. Used as a probe in gel shift assays, fragment -59/-40 formed complexes of differing mobilities when incubated with nuclear protein extracts from the three cell types. Mutation of the putative Sp1 binding site in the probe sequence interfered with protein binding in all three cell types, but anti-Sp1 antibody supershifted a band formed only by airway cell extracts. A model of airway cell-specific MUC 2 transcription is proposed.

Animals↗

PubMed1997

Transcriptional activation of mucin by Pseudomonas aeruginosa lipopolysaccharide in the pathogenesis of cystic fibrosis lung disease.

An unresolved question in cystic fibrosis (CF) research is how mutations of the CF transmembrane conductance regulator, a Cl ion channel, cause airway mucus obstruction leading to fatal lung disease. Recent evidence has linked the CF transmembrane conductance regulator mutation to the onset and persistence of Pseudomonas aeruginosa infection in the airways, and here we provide evidence directly linking P. aeruginosa infection to mucus overproduction. We show that P. aeruginosa lipopolysaccharide profoundly upregulates transcription of the mucin gene MUC 2 in epithelial cells via inducible enhancer elements and that this effect is blocked by the tyrosine kinase inhibitors genistein and tyr-phostin AG 126. These findings improve our understanding of CF pathogenesis and suggest that the attenuation of mucin production by lipopolysaccharide antagonists and tyrosine kinase inhibitors could reduce morbidity and mortality in this disease.

Benzylidene Compounds↗

PubMed1996

Transcriptional regulation of the lysozyme gene in airway gland serous cells.

Lysozyme is expressed in serous, but not mucous, cells of the tracheobronchial glands and thereby constitutes a marker of the serous cell lineage in these glands. To identify DNA regulatory elements and transcription factors mediating the commitment of progenitor cells to the serous cell lineage, we have characterized the regulatory activity and DNA-protein interactions of the 5'-flanking region of the bovine lysozyme gene lys 5a. Results obtained from these studies indicate that although approximately 94 bp of 5'flanking DNA are necessary for high level expression in transient transfection assays, an evolutionarily conserved promoter within 66 bp of the transcription start site is sufficient to confer serous cell-specific expression. Farther upstream, within 6.1 kb of the 5' flanking region, are 4 silencers. Analysis of the serous cell-specific lysozyme promoter by electrophoretic mobility shift assay (EMSA) revealed the presence of binding sites for 3 serous cell nuclear proteins, designated LSF1, LSF2 and LSF3. Binding of LSF2 and LSF3 was localized to a 20-mer subdomain (-50/-30) of the cell-specific promoter using binding competition assays. More accurate identification of the protein binding site(s) was achieved through the use of mutagenesis, which implicated the motif 5' AAGGAAT 3' (-46/-40) in both protein binding and serous cell-specific transcriptional activity. This motif has previously been identified as a binding site for ets protein transcription factors, suggesting that serous cell-specific regulation of lys 5a transcription is partly controlled by the binding of ets-like protein(s) to the motif 5'AGGAAGT3'.

Amino Acid Sequence↗

PubMed1996

Systemic hypoxia dehydrates the space surrounding photoreceptors in the cat retina.

PURPOSE: To assess the effects of systemic hypoxia and hyperoxia on the volume of the subretinal space (SRS). METHODS: The authors measured the concentration of the extracellular space marker tetramethylammonium (TMA+) in the intact cat eye using double-barreled ion-selective microelectrodes. The retina was loaded with TMA+ by a single intravitreal injection. Systemic hypoxia was induced by adding nitrogen to the breathing mixture, and hyperoxia was induced by adding oxygen. RESULTS: Hypoxia produced a slow increase in dark- adapted [TMA+]0, which was prominent in amplitude in the distal portion of the retina, suggesting a shrinkage of the SRS. This effect was essentially proportional to the decrease in arterial oxygen tension (PaO2) below the normoxic level. Dark-adapted (TMA+)0 began to increase at a PaO2 of 60 to 80 mm Hg and was enhanced by 13% to 15% at a PaO2 of 40 mm Hg. Because of its slow onset, the size of the increase also was related to the duration of hypoxia. The light-evoked decrease in (TMA+)0 in the SRS was larger in amplitude during hypoxia than in normoxia. This difference increased with severity of hypoxia, beginning at approximately the same PaO2 as the increase in dark-adapted (TMA+)0. Interestingly, the hypoxic increase in amplitude depended on light intensity, i.e., it was proportionally greater at lower intensities versus higher ones. Background illumination suppressed the hypoxia-induced increase in (TMA+)0 in SRS, inhibiting it by approximately 50% at levels of hypoxia down to a PaO2 of 40 mm Hg. Systemic hyperoxia produced the reverse effect of hypoxia. Between two extreme states, e.g., illumination during hyperoxia (PaO2 > 200 mm Hg) versus severe hypoxia in darkness (PaO2 approximately 40 mm Hg), extracellular volume may change more than 4-fold. CONCLUSIONS: The observations of this study indicate that the space surrounding photoreceptors shrinks in response to hypoxia. This shrinkage should affect concentrations of all ions and metabolites located in the subretinal space.

Animals↗

PubMed1994

Surgical management of the hypopharyngeal and cervical esophageal cancer.

Between December 1979 and December 1992, 15 patients with hypopharyngeal and cervical esophageal cancer were treated surgically. Total pharyngolaryngectomy and partial cervical esophagectomy were performed and the defects were reconstructed with cervical skin flaps in 2 cases. The free jejunal segments were used in 6 cases following total pharyngolaryngectomy and cervical esophagectomy, cervical esophagectomy (larynx preserved) was repaired with free jejunal graft in 1 case. The pharyngogastric anastomosis following total pharyngolaryngoesophagectomy were performed in 4 cases, one of them, used pectoralis major myocutaneous flap for resection of soft tissue and skin of the neck. The pectoralis major myocutaneous flap and forearm free flap in 1 case respectively were used to reconstruct the deficits of total laryngectomy and partial pharyngectomy, and partial pharyngolaryngectomy. In our series, 1, 3, 5 years survival rates were 73.3% (11/15), 50% (6/12) and 55.6% (5/9), respectively. The advantages and disadvantages of a variety of operative procedures and the cervical lymph nodes management will be discussed.

Adult↗

PubMed1994

Light-dependent hydration of the space surrounding photoreceptors in chick retina.

PURPOSE: To characterize the light-evoked increase in the volume (or hydration) of the subretinal space (SRS) of chick retina and to investigate its retinal pigment epithelial (RPE) origin. METHODS: The authors perfused chick retina-RPE-choroid preparations with the extracellular space marker, tetramethylammonium (TMA+), and estimated its concentration ([TMA+]o) using double-barreled, ion-selective electrodes. They recorded dark-light changes in subretinal [TMA+]o and studied the effects of drugs that suppress RPE ion transport and conductances. RESULTS: The authors observed a slow, light-evoked decrease in subretinal [TMA+]o, about 7% in amplitude, that slowly returned to baseline and then increased at light OFF. It was 40% to 65% inhibited by bumetanide and furosemide, known to inhibit RPE apical membrane Na-K-Cl cotransport; 70% to 80% inhibited by DIDS, an inhibitor of RPE basal membrane chloride conductance, and 50% inhibited by 0.5 mM BaCl2, a blocker of the K+ conductance of the RPE apical membrane. Decreases in subretinal [TMA+]o also were produced when the authors lowered [Cl-]o or [K+]o in the SRS by reducing concentrations in the retinal perfusate. The effect on [TMA]o was larger for [Cl-]o than for [K+]o and was inhibited by bumetanide and DIDS. CONCLUSIONS: Changes in subretinal ion concentrations in light and darkness, most likely [K+]o, modify SRS hydration by modulating RPE apical membrane Na-K-Cl cotransport, as well as the conductive effluxes of K+ across the apical membrane and Cl- across the basal membrane. These changes depend principally on the movement of water into or out of the RPE. In turn, subretinal hydration modifies local ion concentrations and the composition of the interphotoreceptor matrix.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1994

Mathematical model of TMA+ diffusion and prediction of light-dependent subretinal hydration in chick retina.

PURPOSE: To derive a mathematical model of TMA+ diffusion across the retina that can be used to estimate the amplitude and kinetics of the light-evoked increase in subretinal hydration and its effect on the concentration of other ions. METHODS: All experimental data were obtained in chick retina-pigment epithelium-choroid preparations as described in the accompanying paper. RESULTS: Diffusional properties of the retina were derived from the time course of [TMA+]o in the subretinal space (SRS) after changes in the retinal perfusate. Then, the SRS volume changes underlying the light-induced [TMA+]o response can be derived using a mathematical model of TMA+ diffusion. Complete retinal depth series of light-evoked [TMA+]o responses could be simulated by producing a corresponding expansion of the SRS. Volume changes inferred from the diffusion model were 2.2 to 3.8 times larger and more prolonged than could be derived directly from delta [TMA+]o. The model predicted up to a 20% peak increase in subretinal-space hydration during illumination. The effects of this volume increase on subretinal K+ and Ca2+ were estimated. These predictions were supported by inhibiting the volume increase with DIDS, which blocks retinal pigment epithelium basal membrane Cl- conductance. CONCLUSIONS: The primary source of light-evoked changes in extracellular TMA+ concentration recorded throughout the retina is an increase in hydration (volume) of the subretinal space. The response spreads to the inner retina by diffusion. Effects of TMA+ diffusion lead to large underestimates of the underlying volume changes. The light-evoked volume change alters the composition of the subretinal space and light-induced responses of other ions.

Animals↗