Biomedical subjects

J Ji

Publications and source records attributed to J Ji.

At least 37 records · Page 2Linked to original sources

PubMed2001

Identification and functional characterization of a novel ryanodine receptor mutation causing malignant hyperthermia in North American and South American families.

Malignant hyperthermia is a pharmacogenetic disorder associated with mutations in Ca(2+) regulatory proteins. It manifests as a hypermetabolic crisis triggered by commonly used anesthetics. Malignant hyperthermia susceptibility is a dominantly inherited predisposition to malignant hyperthermia that can be diagnosed by using caffeine/halothane contracture tests. In a multigenerational North American family with a severe form of malignant hyperthermia that has caused four deaths, a novel RYR1 A2350T missense mutation was identified in all individuals testing positive for malignant hyperthermia susceptibility. The same A2350T mutation was identified in an Argentinean family with two known fatal MH reactions. Functional analysis in HEK-293 cells revealed an altered Ca(2+) dependence and increased caffeine sensitivity of the expressed mutant protein thus confirming the pathogenic potential of the RYR1 A2350T mutation.

Amino Acid Substitution↗

PubMed2001

Population dynamics of phytophagous and predatory mites (Acari: Tetranychidae, Eriophyidae, Phytoseiidae) on bamboo plants in Fujian, China.

The seasonal cycle and population dynamics of Schizotetranychus nanjingensis Ma and Yuan, Aponychus corpuzae Rimando (Tetranychidae), Aculus hambusae Kuang (Eriophyidae) and their natural enemy Tvphlodromus bambusae Ehara (Phytoseiidae) were studied during 1996-1998 in moso bamboo forests in Nanping, Fujian, China. Damage to bamboo leaves was often caused by mixed populations of the three phytophagous species, which displayed different seasonal dynamics: S. nanjingensis fed actively and reproduced in May and from late July to late October (aestivating from June to mid July), Ap. corpuzae was active and reproduced from mid July to late November, and Ac. bambusae from July to next February. During Spring S. nanjingensis was the dominant species with the greatest niche width, but in Summer Ac. bambusae and Ap. corpuzae became dominant and had greater niche widths. In Autumn, Ac. bambusae decreased but both S. nanjingensis and Ap. corpuzae mites increased and the latter became dominant. In winter all species decreased sharply in number. The two spider mite species (S. nanjingensis and Ap. corpuzae) had high niche overlaps in all four seasons. Niche overlaps between the eriophyid Ac. bambusae and the two spider mites were similarly high except during the spring when Ac. bambusae was absent. The predatory mite (T. bambusae) had higher niche overlap with Ap. corpuzae than with others during Autumn and Winter, but during Spring and Summer niche overlap was higher with S. nanjingensis.

Animals↗

PubMed2001

Development of a digital fluorescence sensing technique to monitor the response of macrophages to external hypoxia.

Oxygen plays a very important role in living cells. The intracellular level of oxygen is under tight control, as even a small deviation from normal oxygen level affects major cellular metabolic processes and is likely to result in cellular damage or cell death. This paper describes the use of the oxygen sensitive fluorescent dye tris (1,10-phenanthroline) ruthenium chloride [Ru(phen)(3)] as an intracellular oxygen probe. Ru(phen)(3) exhibits high photostability, a relatively high excitation coefficient at 450 nm (18 000 M(-1) cm(-1)), high emission quantum yield ( approximately 0.5), and a large Stoke shift (peak emission at 604 nm). It is effectively quenched by molecular oxygen due to its long excited state lifetime of around 1 micros. The luminescence of Ru(phen)(3) decreases with increasing oxygen concentrations and the oxygen levels are determined using the Stern-Volmer equation. In our studies, J774 Murine Macrophages are loaded with Ru(phen)(3), which passively permeates into the cells. Fluorescence spectroscopy and digital fluorescence imaging microscopy are used to observe the cells and monitor their response to changing oxygen levels. The luminescence intensity of the cells decreases when exposed to hypoxia and recovers once normal oxygen conditions are restored. The analytical properties of the probe and its application in monitoring the cellular response to hypoxia are described.

Animals↗

PubMed2001

Selective binding of albumin on stearyl poly(ethylene oxide) coupling polymer-modified poly(ether urethane) surfaces.

A tri-block-coupling polymer of stearyl poly(ethylene oxide)-4,4'-methylene diphenyl diisocyanate-stearyl poly(ethylene oxide) (MSPEO), was used as a surface modifying additive (SMA) and the MSPEO-modified poly(ether urethane) (PEU) surfaces were prepared by the process of dip-coating. The surface analysis by XPS revealed the surface enrichment of poly(ethylene oxide) (PEO). On the coating-modified surfaces, the bovine serum albumin (BSA) adsorption, respectively, from the low and high BSA bulk concentration solutions was correspondingly characterized by the methods of radioactive 125I-probe and ATR-FTIR. The bovine serum fibrinogen (Fg)-adsorption from the Fg bulk solution and the BSA-Fg competing adsorption from the BSA-Fg binary solutions were also characterized by radioactive 125I-probe. The reversible BSA-selective in situ adsorption on MSPEO-modified PEU surfaces were achieved, and the performance of blood compatibility on the coating-modified surfaces was also confirmed, respectively, by plasma recalcification time (PRT) and prothrombin time (PT) tests.

Adsorption↗

PubMed2001

Synthesis of flavonoids and their effects on aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues.

Aldose reductase, the key enzyme of the polyol pathway, and oxidative stress are known to play important roles in the complications of diabetes. A drug with potent inhibition of aldose reductase and oxidative stress, therefore, would be a most promising drug for the prevention of diabetic complications. The purpose of this study was to develop new compounds with these dual-effects through synthesis of chalcone derivatives and by examining the structure-activity relationships on the inhibition of rat lens aldose reductase as well as on antioxidant effects. A series of 35 flavonoid derivatives were synthesized by Winget's condensation, oxidation, and reduction of appropriate acetophenones with appropriate benzaldehydes. The inhibitory activity of these derivatives on rat lens aldose reductase and their antioxidant effects, measured using Cu2+ chelation and radical scavenging activities on 1,1-diphenyl-picrylhydrazyl in-vitro, were evaluated. Their effect on sorbitol accumulation in the red blood cells, lenses and sciatic nerves of streptozotocin-induced diabetic rats was also estimated. Among the new flavonoid derivatives synthesized, those with the 2',4'-dihydroxyl groups in the A ring such as 2,4,2',4'-tetrahydroxychalcone (22), 2,2',4'-trihydroxychalcone (11), 2',4'-dihydroxy-2,4-dimethylchalcone (21) and 3,4,2',4'-tetrahydroxychalcone (18) were found to possess the highest rat lens aldose reductase inhibitory activity in-vitro, their IC50 values (concentration of inhibitors giving 50% inhibition of enzyme activity) being 1.6 x 10(-7), 3.8 x 10(-7), 4.0 x 10(-7) and 4.6 x 10(-7) M, respectively. All of the chalcones tested except 3, 18, 23 with o-dihydroxy or hydroquinone moiety showed a weak free radical scavenging activity. In the in-vivo experiments, however, compound 18 with o-dihydroxy moiety in the B ring showed the strongest inhibitory activity in the accumulation of sorbitol in the tissues. It also showed the strongest activity in transition metal chelation and free radical scavenging activity. Of the 35 4,2'-dihydroxyl and 2',4'-dihydroxyl derivatives of flavonoid synthesized, including chalcone, flavone, flavanone, flavonol and dihydrochalcone, some chalcone derivatives synthesized were found to possess aldose reductase inhibition and antioxidant activities in-vitro as well as inhibition in the accumulation of sorbitol in the tissues in-vivo. 3,4,2',4'-Tetrahydroxychalcone (18, butein) was the most promising compound for the prevention or treatment of diabetic complications.

Aldehyde Reductase↗

PubMed2001

Inhibition of prostalglandin E2 production by 2'-hydoxychalcone derivatives and the mechanism of action.

The effects of 14 synthetic 2'-hydroxychalcone derivatives on prostaglandin E2 (PGE2) production in rat peritoneal macrophages stimulated by the protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA), were examined to clarify the structure-activity relationship. 2',4-Dihydroxy-4'-methoxychalcone (compound 3), 2',4-dihydroxy-6'-methoxychalcone (compound 8) and 2'-hydroxy-4'-methoxychalcone (compound 9) suppressed PGE2 production more potently than the other compounds. The IC50 (50% Inhibitory concentration) value for compounds 3, 8 and 9 was calculated to be 3 microM. The activity of cyclooxygenase (COX)-1 was inhibited slightly by compound 9, but that of COX-2 was not inhibited. At concentrations that inhibited the production of PGE2, compound 9 had no effect on the release of radioactivity from [3H]arachidonic acid-labelled macrophages stimulated by TPA. Western-blot analysis revealed that the induction of COX-2 protein by TPA was inhibited by compound 9 in parallel with the inhibition of PGE2 production. Compounds 3 and 8 had similar effects. These findings suggest that 4'-methoxyl and 6'-methoxyl groups are required for the expression of more potent inhibitory activity against PGE2 production, and that the inhibition of PGE2 production by these 2'-hydroxychalcone derivatives is due to the inhibition of TPA-induced COX-2 protein expression.

Animals↗

PubMed2001

Interferon-gamma inhibits in situ expression of PDGF-beta mRNA by smooth muscle cells in injured rabbit arteries after transluminal balloon angioplasty.

OBJECTIVE: To elucidate the mechanism of interferon-gamma (IFN-gamma) to inhibit the restenosis after successful percutaneous transluminal angioplasty (PTA). METHODS: A rabbit vascular restenotic model was constructed and the proliferation of intimal smooth muscle cells (SMCs) were observed by monitoring their expression of proliferating cell nuclear antigen (PCNA) and platelet-derived growth factor beta chain mRNA (PDGF-beta mRNA) at the indicated time points. RESULTS: IFN-gamma could significantly inhibit the expression of PCNA by intimal SMCs one week after denudation, when counting 200 intimal cells for PCNA-positive reactions with an inhibitory rate of 88.50% (P < 0.001). IFN-gamma could downregulate in situ expression of PDGF-beta mRNA by these cells as we calculated the average number of PDGF-beta mRNA positive cells per square millimetre area at x 400 magnification with reduced rates of 86.85% in 1 week group (P < 0.001), of 93.66% in 2 week group (P < 0.001) and of 52.92% in 4 week group (0.02 < P < 0.05), respectively. CONCLUSIONS: The local production of PDGF-beta by vascular intimal SMCs via an autocrine mechanism may be responsible for continuous proliferation of these cells and the formation of neointima after injury. This could be inhibited by IFN-gamma through downregulating the expression of PDGF-beta mRNA. These results provide an in vivo basis for IFN-gamma to be used clinically for the management of restenosis after percutaneous transluminal angioplasty.

Angioplasty, Balloon↗

PubMed2001

[The clinical effect of non-penetrating trabecular surgery with reticulated sodium hyaluronate implant for treatment of primary open-angle glaucoma].

OBJECTIVE: To evaluate the clinical effect of non-penetrating trabecular surgery (NPTS) with reticulated sodium hyaluronate implant in primary open-angle glaucoma (POAG). METHODS: NPTS with reticulated sodium hyaluronate implant was performed on 27 eyes of 25 patients with POAG. The procedure consisted of excising a deep scleral tissue including the external wall of the Schlemm's canal under a scleral flap without opening the anterior chamber, as the inner wall of the canal was left in place. Then placing a 3.0 mm x 4.5 mm x 0.5 mm or 3.5 mm x 3.5 mm x 3.5 mm reticulated sodium hyaluronate implant was placed under the flap, so that the aqueous humor may filter through the thin layer of trabeculocorneal membrane spontaneously without forming a flat chamber. The postoperative intraocular pressure (IOP), inflammation and filtering bleb were analyzed. All of patients undertook ultrasound biomicroscopy (UBM) and gonioscopy to evaluate the surgical site on the postoperative 2 weeks, 3, 6 and 9 months. The mean follow-up was (6.61 plus minus 2.47) months. RESULTS: The IOP decreased from a mean preoperative value of (26.36 +/- 9.02) mm Hg (1 mm Hg = 0.133 kPa) to a mean postoperative value of (14.18 +/- 3.51) mm Hg (t = 6.875, P < 0.05). The number of anti-glaucomatous medications, topical or systemical, was reduced from (2.96 +/- 1.43) sorts preoperatively to (0.77 +/- 1.07) sorts postoperatively. The visual acuity remained stable (no statistical difference with chi(2) test). Six eyes had elevated IOP after operation and were controlled by eyedrops or trabecular puncture with ND: YAG laser. A slight hyphema occurred in 4 eyes with small puncture during operation. The complications such as flat chamber, inflammation and choroidal detachment were not observed. The UBM showed that the sodium hyaluronate implant degraded and a transparent liquid space existed under the scleral flap in all of patients at postoperative 3 months. The gonioscopy showed that at the surgical site the thinner and semitransparent trabecular membrane and changes of a transparent cavity could be seen in 23 eyes. In the other eyes, at the site the trabecula was translucent. The filtering blebs were formed in 8 eyes. CONCLUSION: Non-penetrating trabecular surgery with reticulated sodium hyaluronate implant can effectively lower the IOP and reduce the sorts of anti-glaucomatous medications. The visual acuity may remain unchanged, and no serious complications commonly seen in the traditional trabeculectomy occur. The procedure is a new simple and effective one for the treatment of POAG.

Adolescent↗

PubMed2000

Strategy for qualitative and quantitative analysis in proteomics based on signature peptides.

This paper describes a new analytical strategy for identifying proteins in concentration flux based on isotopic labeling peptides in tryptic digests. Primary amino groups in peptides from control and experimental samples were derivatized with acetate and trideuteroacetate, respectively. After mixing samples thus labeled from these two sources, the relative concentration of peptides was determined by isotope ratio analysis with MALDI and ESI mass spectrometry. More than a 100-fold difference in relative concentration could be detected. Simplification of complex tryptic digests prior to mass spectral analysis was achieved by selection of histidine-containing peptides with immobilized metal affinity sorbents or of glycopeptides by lectin columns. Because most of these peptides have sequences that are unique to a single protein, they are a signature of the protein from which they were derived; providing a facile route to protein analysis.

Chromatography, Affinity↗

PubMed2000

Synthesis and application of submicrometer fluorescence sensing particles for lysosomal pH measurements in murine macrophages.

Phagocytosis of bioparticles such as bacteria and viruses by macrophages is a critical component of the immune response against infections. In this paper we describe the synthesis of submicrometer fluorescent particles with pH sensing capability. The particles are used to measure the pH and to monitor the effect of chloroquine, an antimalarial drug, on the pH in the lysosome, the cellular organelle involved in the phagocytosis process. The synthesis of the pH sensing particles is realized by the covalent attachment of amine reactive forms of Oregon Green (pH sensitive dye) and Texas Red (pH insensitive dye) to the surface of amino-modified submicrometer polystyrene particles. The particles are absorbed by J774 Murine Macrophages through phagocytosis and directed to lysosomes. Despite the high lysosomal levels of digestive enzymes and acidity, the absorbed particles remain stable for 12 h in the cells when they are stored in a PBS buffer solution at pH 7.4. The pH dynamic range of the sensing particles is between pH 4.5 and 7 with a sensitivity of 0.1 pH units. Exposure of the cells to chloroquine increases the lysosomal pH from 4.8 to 6.5. The effect is concentration-dependent.

Animals↗

PubMed2000

Self-Assembly and Surface Structure of an Amphiphilic Graft Copolymer, Polystyrene-graft-omega-Stearyl-Poly(ethylene oxide).

Surface properties of the polystyrene-graft-omega-stearyl-poly(ethylene oxide) (PS-g-SPEO) have been characterized by X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), contact angle, and spin probe techniques. The XPS results indicate that the surface and bulk composition of the PS-g-SPEO copolymers differ remarkably from each other. The stearyl and EO components enrich at the copolymer/air interfaces due to the self-assembly of the stearyl groups. At the PS-g-SPEO-72.6 surface (the x in PS-g-SPEO-x indicates the bulk density of the SPEO in wt%), the self-assembly of the hydrophobic stearyl groups is strong enough to form a stable liquid crystalline phase as indicated by DSC. At polymer/water interfaces, PS-g-SPEO-72.6 presents a hydrophilic surface with low PEO mobility, whereas PS-g-SPEO-50.6 and PS-g-SPEO-31.0 present the hydrophobic surface with high PEO mobility. The two different types of the surfaces, with different characters in surface energy, surface mobility of PEO, and surface architecture of SPEO, will be quite valuable as models for detecting the synergistic action of the PEO chains and the stearyl groups (specific ligand for albumin binding) in protein solutions. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Signature-peptide approach to detecting proteins in complex mixtures.

The objective of the work presented in this paper was to test the concept that tryptic peptides may be used as analytical surrogates of the protein from which they were derived. Proteins in complex mixtures were digested with trypsin and classes of peptide fragments selected by affinity chromatography, lectin columns were used in this case. Affinity selected peptide mixtures were directly transferred to a high-resolution reversed-phase chromatography column and further resolved into fractions that were collected and subjected to matrix-assisted laser desorption ionization (MALDI) mass spectrometry. The presence of specific proteins was determined by identification of signature peptides in the mass spectra. Data are also presented that suggest proteins may be quantified as their signature peptides by using isotopically labeled internal standards. Isotope ratios of peptides were determined by MALDI mass spectrometry and used to determine the concentration of a peptide relative to that of the labeled internal standard. Peptides in tryptic digests were labeled by acetylation with acetyl N-hydroxysuccinimide while internal standard peptides were labeled with the trideuteroacetylated analogue. Advantages of this approach are that (i) it is easier to separate peptides than proteins, (ii) native structure of the protein does not have to be maintained during the analysis, (iii) structural variants do not interfere and (iv) putative proteins suggested from DNA databases can be recognized by using a signature peptide probe.

Amino Acid Sequence↗

PubMed2000

Synthesis and anti-inflammatory and analgesic activities of pyridyloxy- and phenoxyalkanoic acid derivatives.

Synthesis of pyridyloxy-, pyridyloxyphenoxy- and phenoxylphenoxyalkanate derivatives and their anti-inflammatory and analgesic activities were investigated. Analysis of structure-activity relationships showed that in pyridyloxyalkanoic acid derivatives anti-edematous potency was associated with the presence of chlorophenoxypropionic acid moiety and 2-nitrated methyl propionates contributed to the analgesic activity.

Analgesics, Non-Narcotic↗

PubMed2000

Detection of integrins in cataract lens epithelial cells.

PURPOSE: To detect the expression of integrin subunits in lens epithelial cells (LECs) of human cataracts. SETTING: Research Laboratory, International Intraocular Implant Training Centre, Tianjin Medical University, China. METHODS: The circular sections of the anterior capsules with attached LECs were obtained during cataract surgery from 100 patients. The LECs were stained with an avidin-biotin-complex immunohistochemical technique using 5 monoclonal antibodies specific for alpha subunits 2, 3, 5 and beta subunits 1, 2. RESULTS: All integrin subunits studied were found to varying degrees in specimens. The positive percentages were 70%, 65%, 75%, 70%, and 80%, respectively. CONCLUSION: Integrin subunits were present in LECs of human cataracts. These molecules may serve in the adhesion of LECs to the lens capsule and play a role in cell-posterior capsule interaction after cataract surgery.

Antibodies, Monoclonal↗

PubMed2000

Arrestment response of the predatory mite Amblyseius longispinosus to Schizotetranychus nanjingensis webnests on bamboo leaves (Acari: Phytoseiidae, Tetranychidae).

The response of the predatory mite Amblyseius longispinosus (Acari: Phytoseiidae) to the webnest of the spider mite Schizotetranychus nanjingensis (Acari: Tetranychidae) was examined using two-choice tests in the laboratory. A. longispinosus females were found significantly more often on leaves with webnests than on leaves without webnests and were often observed searching under the webbing. Because spider mites and their eggs were removed from the webnests before experiments, predators responded to stimuli associated with webbing, mite feeding damage and other residues in the webnests.

Animals↗

PubMed2000

Inwardly rectifying K(+) channels in esophageal smooth muscle.

The whole cell patch-clamp technique was used to investigate whether there were inwardly rectifying K(+) (K(ir)) channels in the longitudinal muscle of cat esophagus. Inward currents were observable on membrane hyperpolarization negative to the K(+) equilibrium potential (E(k)) in freshly isolated esophageal longitudinal muscle cells. The current-voltage relationship exhibited strong inward rectification with a reversal potential (E(rev)) of -76.5 mV. Elevation of external K(+) increased the inward current amplitude and positively shifted its E(rev) after the E(k), suggesting that potassium ions carry this current. External Ba(2+) and Cs(+) inhibited this inward current, with hyperpolarization remarkably increasing the inhibition. The IC(50) for Ba(2+) and Cs(+) at -60 mV was 2.9 and 1.6 mM, respectively. Furthermore, external Ba(2+) of 10 microM moderately depolarized the resting membrane potential of the longitudinal muscle cells by 6.3 mV while inhibiting the inward rectification. We conclude that K(ir) channels are present in the longitudinal muscle of cat esophagus, where they contribute to its resting membrane potential.

Animals↗

PubMed2000

Developmental and hormonal regulation of the expression of oligodendrocyte-specific protein/claudin 11 in mouse testis.

The proliferation and differentiation of testicular progenitor stem cells into highly specialized germ cells (spermatozoa) are largely controlled by the hormonally (FSH and testosterone) regulated adjacent supporting Sertoli cells. However, the factors involved in this control remain largely unknown. In the present study, the technique of differential display PCR was used to identify target transcripts to FSH action in cultured murine Sertoli cells. Among these target transcripts, we identified the oligodendrocyte-specific protein (OSP), also known as claudin 11, which had recently been shown to play a key role in the formation of the hematotesticular barrier. Our data show that the testicular expression of OSP is dependent upon male gonad development and systemic and local signaling molecules. Indeed, OSP is expressed early in fetal development in Sertoli cells, immediately after the peak of SRY (sex-determining region, Y gene) expression, but just before that of the anti-Mullerian hormone. Postnatally, OSP expression starts to increase from day 3 to reach a plateau between days 6 and 16 postnatally. In the prepubertal and adult testes, an apparent decline in OSP messenger RNA (mRNA) levels was found, probably because of the increasing number of germ cells (which do not express OSP). Among the signaling molecules that control testicular OSP expression, we have identified FSH and tumor necrosis factor-alpha (TNFalpha). Indeed, using a model of purified cultured mouse Sertoli cells, we demonstrate that FSH inhibits, in a dose (ED50 = 4 ng/ml)- and time (maximal effect after 24 h)-dependent manner, the levels of OSP mRNA. Such an inhibitory effect was mimicked by 8-bromo-cAMP, suggesting that FSH may use the cAMP/protein kinase A pathway to inhibit OSP mRNA levels. TNFalpha was also shown to inhibit OSP expression in cultured Sertoli cells. The maximal effect was observed after 48 h of TNFalpha treatment with an ED50 of 4.5 ng/ml. Together, our results indicate that OSP expression 1) starts during fetal life at a critical period, probably under SRY control and during testicular formation; and 2) is regulated by hormones (FSH) and cytokines (TNFalpha) in the adult testis, suggesting a critical role for these molecules in the (re)modeling process of the hematotesticular barrier during spermatogenesis.

Animals↗

PubMed2000

Inhibitory effects of 2'-hydroxychalcones on rat lens aldose reductase and rat platelet aggregation.

Inhibitory effects of synthetic 2'-hydroxychalcone derivatives on rat lens aldose reductase (RLAR) and on platelet aggregation were investigated for the prevention or the treatment of chronic diabetic complications. 5'-chloro-4,2'-dihydroxychalcone (8) and 5'-chloro-3,2'-dihydroxychalcone (27) exhibited a potent inhibitory effect on rat platelet aggregation induced by ADP (IC50=0.10 and 0.06 mg/ml, respectively) and collagen (IC50=44 and 16 microg/ml, respectively) but showed relatively weak inhibitory activities on RLAR.

Aldehyde Reductase↗