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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 685 records · Page 38Linked to original sources
PubMed1997

Effect of transforming growth factor beta-1 in endotoxin-induced uveitis.

PURPOSE: Transforming growth factor beta-1 (TGF beta-1) can modulate inflammation. Endotoxin-induced uveitis (EIU) is characterized by acute ocular inflammation related to the release of cytokines, including interleukin (IL)-6. The authors investigated the effect of TGF beta-1 on EIU in mice. METHODS: Three independent experiments were performed. Endotoxin-induced uveitis was induced in C3H/HeN mice by an injection of 200 micrograms of lipopolysaccharide (LPS). Two micrograms of TGF beta-1 in 0.1 ml phosphate-buffered saline (PBS) or 0.1 ml PBS alone was administered intraperitoneally at 8 hours after LPS injection. Twenty-four hours after LPS injection, the aqueous humor of the right eyes was collected for leukocyte count, protein concentration, and IL-6 assay. Left eyes were processed for routine histology. RESULTS: TGF beta-1-treated mice showed less ocular inflammation histologically than to the animals that were given PBS. This was confirmed by decreases in leukocyte count, protein concentration, and IL-6 level in the aqueous humor. CONCLUSIONS: TGF beta-1 inhibits the development of EIU. TGF beta-1 may be useful for the modulation of uveitis in humans.

Animals↗
PubMed1997

GAP-43 phosphorylation by PKC in rat cerebrocortical synaptosomes: effect of antidepressants.

Recent evidence, including our previous work, indicates that changes in both c-AMP and phospholipid-dependent protein kinases (PKA and PKC) may be involved in neuroadaptive mechanisms occurring in brain after repeated administration of antidepressants. The purpose of this study was to examine the phosphorylation of a major PKC substrate involved in modulation of neurotransmitter release, GAP-43, in a synaptosomal preparation from rat cerebral cortex after repeated administration of fluxetine (FL) and desipramine (DMI). Groups of male rats were treated for 21 days with either FL (5 mg/kg/day, i.p.), DMI (10 mg/kg/day, i.p.) or vehicle (controls) and cortical synaptosomes were prepared 48 h or 24 h after the last injection. Synaptosomal membrane proteins were resolved by SDS-PAGE. Western immunoblotting and immunoprecipitation with anti-GAP-43 antibody have identified the GAP-43 protein as a single distinct band of apparent molecular weight of 56 kDa. The extent of phosphorylation of GAP-43 protein by native PKC in synaptosomes of rats treated with either FL or DMI was not significantly different from that observed in control animals. The previously observed suppression of basal PKC activity in rat cortical synaptosomes by FL and DMI treatment was thus not reflected in altered GAP-43 phosphorylation. It is thus unlikely that changes in GAP-43 phosphorylation are involved in antidepressant-induced modulation of 5-HT release.

Animals↗
PubMed1997

IL-1 upregulates keratinocyte growth factor and hepatocyte growth factor mRNA and protein production by cultured stromal fibroblast cells: interleukin-1 beta expression in the cornea.

PURPOSE: To determine whether interleukin 1 beta (IL-1 beta) messenger RNA (mRNA) and protein were expressed in corneal cells and to examine the effects of IL-1 alpha and IL-1 beta on the expression of hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) mRNAs and proteins in corneal stromal fibroblasts. METHODS: IL-1 beta mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). IL-1 beta protein was detected by immunohistologic tests. Changes in the expression of HGF and KGF mRNAs and proteins in response to stimulation of cultured corneal stromal fibroblasts with IL-1 alpha and IL-1 beta were monitored by Northern and Western blotting, respectively. RESULTS: IL-1 beta mRNA is expressed in human primary cultured corneal epithelial, stromal fibroblast, and endothelial cells. IL-1 beta protein was detected in epithelium and endothelium in fresh frozen human and rabbit corneal tissue. Little, if any, IL-1 beta was detected in the unwounded corneal stroma. IL-1 alpha and IL-1 beta at 10 ng/ml upregulated the levels of HGF and KGF mRNAs and proteins in cultured human corneal fibroblasts. CONCLUSIONS: IL-1 alpha and IL-1 beta may serve as key modulators in an epithelial-stromal regulatory loop in the cornea. These data and previously published observations support the hypothesis that corneal epithelial wounding releases IL-1 alpha and IL-1 beta from epithelial cells; these cytokines in turn upregulate HGF and KGF mRNA and protein levels in keratocytes, and HGF and KGF released by the keratocytes modulate healing of the wounded corneal epithelial cells by regulating proliferation, motility, and differentiation.

Animals↗
PubMed1997

Autoantigens in insulin-dependent diabetes mellitus: molecular cloning and characterization of human IA-2 beta.

In this study, we describe the isolation, expression, and characterization of a new member of the transmembrane protein tyrosine phosphatase family from human brain, designated IA-2 beta. The 3853-bp cDNA encodes 986 amino acids with a molecular mass of 108,044 daltons (a predicted pI value of 5.8). The intracellular domain of human IA-2 beta is 74% identical to human IA-2. Northern blot analysis showed that IA-2 beta cDNA recognized two transcripts (approximately 5.0 kb and 4.0 kb) in four of five human insulinomas, one glucagonoma, and in normal human brain, pituitary, and pancreas, but not in a variety of other normal tissues. Rabbit antiserum, raised against the intracellular domain of IA-2 beta, reacted with pancreatic islets. Treatment of in vitro-translated full-length IA-2 beta protein with trypsin converted it into a 37-kD fragment. Using recombinant human IA-2 beta, we developed a radioimmunoprecipitation assay to measure autoantibodies in the sera of patients with insulin-dependent diabetes mellitus (IDDM). Seventy-six new-onset IDDM patients were tested. Thirty-seven percent (28 of 76) of the IDDM sera-but less than 1% of the control sera (1 of 174)-reacted with IA-2 beta. The same IDDM sera tested for autoantibodies to IA-2 and glutamic acid decarboxylase (GAD65) showed that 64% (49 of 76) and 57% (43 of 76), respectively, were positive. All but two of the IA-2 beta autoantibody-positive sera also reacted with IA-2, supporting the close sequence similarity between the two molecules. Combination of any two markers, such as IA-2 beta and IA-2, or IA-2 beta and GAD65, or IA-2 and GAD65, revealed that 67%, 74%, and 87% of IDDM sera were positive for autoantibodies, respectively. Blocking of IDDM sera with recombinant IA-2, IA-2 beta, or GAD65 resulted in marked inhibition of reactivity of IDDM sera with pancreatic islet sections as measured by islet cell autoantibody immunofluorescence. This result suggests that these three autoantigens are the major targets of islet-cell autoantibody reactivity.

Adolescent↗
PubMed1997

Hepatocyte growth factor, keratinocyte growth factor, and other growth factor-receptor systems in the lens.

PURPOSE: To examine the expression and function of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), epidermal growth factor (EGF) and other growth factor-cytokine-receptor systems in lens epithelial cells. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis were used to examine the expression of messenger RNAs in primary cultured rabbit and human lens cells and in ex vivo rabbit lens tissue. Protein expression and the effect of HGF and KGF on crystallin expression in lens epithelial cells were evaluated by immunoprecipitation and Western blot analysis. The effect of exogenous HGF, KGF, and EGF and of the coculture of lens epithelial cells with corneal endothelial cells on the proliferation of rabbit lens cells in a Transwell system was determined by cell counting. RESULTS: Messenger RNAs and proteins of HGF and KGF were expressed in primary rabbit lens epithelial cells and in ex vivo rabbit lens epithelial tissue. Human lens cells also expressed the mRNAs. Other growth factors and receptor messenger RNAs were also expressed. Hepatocyte and keratinocyte growth factors, and coculture with corneal endothelial cells stimulated proliferation of rabbit lens epithelial cells. In first-passage rabbit lens cells, HGF, KGF, and EGF increased the expression of alpha and beta crystallins. CONCLUSIONS: Hepatocyte and keratinocyte growth factor-receptor systems are expressed in lens cells. HGF and KGF are not expressed in epithelial cells in such tissues as skin, cornea, and lacrimal gland in which fibroblastic and epithelial cells interact in the formation of an organ. Expression of these growth factors in the lens may have evolved because the lens cells are relatively isolated within the anterior chamber of the eye. Our results suggest, however, that growth factors released by the corneal endothelium also could modulate lens functions (aquecrine interactions).

Animals↗
PubMed1997

A desensitization of hypothalamic 5-HT1A receptors by repeated injections of paroxetine: reduction in the levels of G(i) and G(o) proteins and neuroendocrine responses, but not in the density of 5-HT1A receptors.

The aim of the present study was to determine whether the previously observed desensitization of hypothalamic 5-hydroxytryptamine1A (5-HT1A) receptors, during daily injections of fluoxetine, is mediated by sustained blockade of 5-HT reuptake. In the present study, we examined the time course effects of another 5-HT uptake inhibitor, paroxetine. Paroxetine reduced the oxytocin, adrenal corticotropic hormone and corticosterone responses to a challenge with the 5-HT1A agonist 8-hydroxy-2-(dipropylamino)tetralin. These reductions in hormone responses were significant after 3 daily injections and reached a maximum after 7 daily paroxetine injections. These hormone responses remained maximally suppressed after 14 daily injections of paroxetine. A single day of paroxetine treatment did not alter the hormone responses to 8-hydroxy-2-(dipropylamino)tetralin. Repeated injections of paroxetine did not reduce the density of 5-HT1A receptors in any brain region but did produce a gradual reduction in the levels of G(i) and G(o) proteins in a region-specific manner. The time course of the paroxetine-induced reduction in the level of G(i1) and G(i3) proteins in the hypothalamus was similar to the effect previously observed with fluoxetine and was also similar to the time course of paroxetine-induced reductions in oxytocin and adrenal corticotropic hormone responses to 8-hydroxy-2-(dipropylamino)tetralin. In conclusion, these results suggest that blockade of 5-HT uptake sites produces a delayed and gradual desensitization of 5-HT1A receptors in the hypothalamus. This desensitization is not due to changes in the density of hypothalamic 5-HT1A receptors. Reduction in the hypothalamic level of G(i3) proteins may play a role in the desensitization of 5-HT1A receptor systems. However, reductions in G(i1) or G(o) proteins cannot be excluded as potential mediators of the desensitization of 5-HT1A receptor systems.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1997

Special features of acute infection due to Schistosoma japonicum in urban and rural areas in China.

The statistical analysis of six indices: sex, age, occupation, time of onset, mode of infection and educational level of acute cases infected by Schistosoma japonicum in 1990 and 1994 respectively in Wuhu city was carried out. No significant differences were found in the five indices between 1990 and 1994 in Wuhu city except sex. There were significant differences between the urban and rural areas in all six indices.

Adult↗
PubMed1997

[Effects of electric fields on the cellular structure of the regenerated nerve].

Eighty adult SD rats were randomly divided into four groups of 20 each: 1. local electrostimulation of nerve stump (Group LS); 2. electrostimulation of myeloneure (Group N); 3. electrostimulation of the denervated muscle (Group M); and 4. Control (Group C). 5 millimeters of the left sciatic nerve of the rat was excised and the severed nerve was bridged with a silicon tube. The gap between the stumps was about 10 millimeters. On the 3rd day and the 1st, 2nd, 3rd, 4th week after surgery, samples were taken and processed for microscopic examinations to observe the effects of electric fields on cellular structural development of regenerated axons, especially on the proliferation and migration of Schwann's cell and fibroblasts, etc. The number of the axon and capillary, the degree of axon maturity and myelinated axon proportion were also observed. The results showed that electrostimulation enhanced nerve regeneration by, 1. promoting the form of matrix bridge; 2. stimulating Schwann's cell and fibroblast migration and proliferation; 3. promoting vascularization of regenerating nerves; and 4. direct electrophoretic effects on structural protein of growth cone.

Animals↗
PubMed1997

[Relationship between asthma and activated T-lymphocytes and interleukin-4].

Several studies have suggested that activated T-lymphocytes and its derived cytokines are involved in asthma pathogenesis. To investigate the role of activated T-lymphocytes and interleukin-4 (IL-4) in asthma pathogenesis, we measured soluble interleukin-2 receptor (sIL-2R) and IgE concentrations in serum and production of IL-4 in situumlated peripheral blood mononuclear cell cultures from asthmatics by means of ELISA. The results showed: (1) sIL-2R (512.82 x 10(3) +/- 264.62 x 10(3) U/L) and IL-4 (1,842.42 +/- 824.60 ng/L) levels in acute severe asthmatics were significantly higher than those of controls (242.32 x 10(3) +/- 108.64 x 10(3) U/L and 406.32 +/- 62.16 ng/L, P < 0.01); (2) there was a positive relationship between IL-4 and serum total IgE (r = 0.492); there was a significantly negative relationship between IL-4 and FEV1% (r = -0.821, P < 0.05); (3) after intravenous administration of dexamethasone (DXM) 5 mg daily for 5 days, sIL-2R and IL-4 decreased respectively to (332.61 x 10(3) +/- 124.62 x 10(3) U/L and 314.10 +/- 72.08 ng/L, P < 0.05). These data indicate that activated T-lymphocytes and its derived IL-4 play an important role in asthma pathogenesis and that the effect of steroid on the treatment of asthma is partly due to inhibition of activated T-lymphocytes and IL-4 release.

Adolescent↗
PubMed1997

[Close injury of the tendon at wrist].

Because of the complicated causes and variable clinical signs, closed injury of tendons at wrist is difficult to diagnosis and treat. Twenty-six cases of tendon ruptur were reported. Among them, 11 cases were caused by bone fracture or dislocation, 8 cases were caused by rheumatoid synovitis, 5 cases were caused by synovial tuberculosis, and 2 cases caused by other. The pathogenesis and clinical signs were analyzed. Twenty-three cases were treated by tendon transfer and 3 cases were treated by tendon transplantation. By average follow-up of 16 months (ranged 6 months to 4 years), the results were as follows: the clip strength and both active and positive motion of fingers were restored in 19 caese, 75% of those were restored in 7 cases and 50% of those were restored in 2 cases. It was suggested that diagnosis, treatment and function rehabilitation should be carried out early, and tendon transfer or tendon transplatation were the method on priority.

Adolescent↗
PubMed1997

[Repair of pulp defect of thumb by free palmaris brevis musculocutaneous flap].

It is difficult to repair the pulp defect of finger with good function. Here reported two cases of pulp defect of the thumb which were repaired with free palmris brevis musculo-cutaneous flap. The flap was designed as the following: taken the line crossing the pisiform and metacarpo-phalangeal joint of the little finger as the longitudinal axis of the flap. The proximal end of the flap was at the level of pisiform and the distal end was the distal transverse palmar crease. The radial border was the radial side of the palmris brevis and ulnar border was the ulnar edge of the palm. The flap should not be larger than 6.5 cm x 2.5 cm. The flap was dissected with proper ulnar vessels and the accompanying arterial branch and superficial branch of the ulnar nerve. The flap was transferred to repair the pulp defect of the thumb. The vessels were anastomosed with the radial artery and cephalic vein at the snuffbox. The nerves were sutured to the digital nerve. Three months after operation, the defect was healed and the sensation of pulp was recovered. The donor area was painless and without sensation disturbance. The motion of the little finger was normal. The function of the thumb was restored. It was concluded that the palmaris brevis musculocutaneous flap is one of the best donor region to repair pulp defect of thumb.

Adult↗
PubMed1997

[Evaluation of electrophysiological diagnosis of concealed accessory pathway (CAP) during transesophageal atrial pacing (TEAP)].

CAP were diagnosed by TEAP using RPE intervals in 55 cases of paroxysmal supraventricular tachycardia (PSVT). There were no obvious CAP manifestations of ECG in those cases, the mean RPE interval during tachycardia was 140 +/- 29 ms, and the lower limit of x +/- 2 s was 82 ms. Among them, the VA intervals were measured by electrocardiophysiological examination in 21 cases. The mean value was 130 +/- 25 ms, and the lower limit of x +/- 2 s was 80 ms. The results suggest that RPE over 82 ms may be an important diagnostic threshold cut off point of atrioventricular reciprocation.

Adolescent↗
PubMed1997

[The study of acute clinical electrophysiological effects of propafenone on paroxysmal supraventricular tachycardia using transesophageal atrial pacing technique].

Trans-esophagus atrial pacing (TEAP) was employed to evaluate the acute electrophysiological effects of propafenone administrated intravenously in 50 patients with SVT. Forty three of the subjects are patients with atrial ventricular reciprocating tachycardia (AVRT). Seven of them were involved in atrioventricular nodal reentry tachycardia (AVNRT). The results indicate that propafenone exerts an obvious inhibitory effect on both the dual atrioventricular node pathways and the accessory pathways, with the latter one being markedly affected. In addition, propafenone can deter the antegrade and retrograde conduction and prolong the refractory period of the accessory pathways. Still more, it results in preceding of the Wenchebach and 2 to 1 block point of the atrioventricular node conduction. All these promise the potential terminating effect on tachycardia. Propafenone has little effects on sinus node. Prolongation of sinus node recovery time (SNRT) to 3600 ms following drug administration was observed in only one patient who has a history of sinus bradycardia.

Adolescent↗
PubMed1996

Biosynthesis and function of all-trans- and 9-cis-retinoic acid in parathyroid cells.

We demonstrate that cultured human and bovine parathyroid cells incubated with all-trans-[11,12-3H]-retinol convert this tracer into all-trans- and 9-cis-retinoic acid. By using RT-PCR, cellular retinol-binding protein type I (CRBP I), cellular retinoic acid binding protein I and II (CRABP I and II), retinoic acid receptors (RARs) alpha, beta and gamma, and 9-cis-retinoic acid receptor (RXR) alpha transcripts were detected in human parathyroid cDNA. CRBP I and CRABP I expression was confirmed by immunohistochemistry. Both 9-cis- and all-trans-RA were found to suppress parathyroid hormone (PTH) secretion from dispersed human adenomatous parathyroid cells, which was augmented by combined treatment with 1mM RA and 100 nM 1,25 (OH)2D3. The present data establish parathyroid gland as a target for retinoids and as a site of synthesis of the hormonal forms of vitamin A (retinol), all-trans- and 9-cis-retinoic acid.

Alitretinoin↗
PubMed1996

Cloning and sequence analysis of the candidate nicotinic acetylcholine receptor alpha subunit gene tar-1 from Trichostrongylus colubriformis.

A T. colubriformis genomic library in lambda EMBL3 was screened for sequences homologous to the Caenorhabditis elegans unc-38 nicotinic acetylcholine receptor (nAChR) alpha-subunit gene. The candidate gene tar-1 (for Trichostrongylus acetylcholine receptor subunit gene 1) comprising 13704 base pairs was thus identified. BLAST comparison of the sequenced clone with GenBank, followed by comparison of translated regions in six reading frames with protein databases, identified clearly defined tracts corresponding to 12 putative exons sharing high sequence homology to other nAChR genes and able to code for sequential regions of a putative nAChR alpha-subunit protein (tar-1). Tar-1 shares sequence similarities with over 40 nAChR subunit proteins. The highest similarity (91.6%) is with unc-38, suggesting that nAChR sequences from nematodes are closely related. The sequence includes motifs typical of these molecules including adjacent cysteine residues at the ACh binding site and four transmembrane regions. The DNA sequence presents the longest genomic tract described for this organism and should prove useful as a probe source in the search for nAChR genes from this and other nematodes and for studying the molecular mechanism of resistance to levamisole, a drug which is known to act on nAChRs of worms and which is widely used for parasite control.

Amino Acid Sequence↗
PubMed1996

Diorganotin(IV) antitumor agent. (C2H5)2SnCl2 (phen)/nucleotides aqueous and solid-state coordination chemistry and its DNA binding studies.

This contribution reports a solution and solid-state study of the aqueous nucleotide coordination chemistry of the diethyltin(IV) antitumor agent, (C2H5)2SnCl2(phen). [trans-en2Os(eta-H2)] (CF3SO3)2, a versatile 1H NMR probe for biomolecules, is first used to investigate the interaction of (C2H5)2SnCl2(phen) with DGMP in neutral aqueous solution, and then the synthesis of mixed-ligands complexes formulated as (C2H5)2SnCl(phen)(Nu) (Nu is nucleotide) by reactions of (C2H5)2SnCl2(phen) with equimolar nucleotides under biologically relevant conditions is described. The new complexes were characterized by 500 MHz 1H, 31P NMR spectra; these spectroscopic data suggest that one of cis-chloro atoms in (C2H5)2SnCl2(phen) is substituted by nucleotide, and that Sn(IV) is directly coordinated to the phosphate group of the nucleotide. No evidence was found for the coordination via donor atoms of the base. On the basis of the above model studies, absorbance, fluorescence and cyclic voltammetric methods, viscosity determination, as well as agrose gel electrophoresis of superhelical pBR322 plasmid DNA were used to study the interaction of (C2H5)2SnCl2(phen) with DNA. The results indicate that (C2H5)2SnCl2(phen) binds to DNA by double modes. The drug first reacts electrostatically with the sugar-phosphate backbone of DNA; this results in changes of DNA conformation, and then phen ligand can intercalate into double-helix DNA and cause unwinding of the DNA.

Antineoplastic Agents↗