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Biomedical subjects

C Ji

Publications and source records attributed to C Ji.

At least 73 records · Page 4Linked to original sources
PubMed1995

In utero and postnatal effects of sidestream cigarette smoke exposure on lung function, hyperresponsiveness, and neuroendocrine cells in rats.

We evaluated whether sidestream smoke (SS) exposure in utero and/or postnatally causes airway obstruction and hyperresponsiveness, and whether the effect is associated with neuroendocrine cell hyperplasia. Pregnant Sprague-Dawley rats were exposed to filtered air (FA) or to SS (total suspended particulate concentration, 1.00 +/- 0.07 mg/m3, CO, 4.9 +/- 0.7 ppm; nicotine, 344 +/- 85 micrograms/m3; mean +/- SD) for 4 hr/day, 7 days/week from Day 3 of gestation until birth and then their female pups were exposed to either FA or SS for 7-10 weeks postnatally. This resulted in four exposure conditions: in utero FA followed by postnatal FA (FA/FA), in utero FA followed by postnatal SS (FA/SS), in utero SS followed by postnatal FA (SS/FA), and in utero SS followed by postnatal SS (SS/SS). The lungs from the pups (n = 6-8 of each exposure combination) were then placed in an isolated buffer-perfused system where transpulmonary pressure, airflow, and pulmonary artery pressure (Ppa) were measured while increasing doses of methacholine were injected into the pulmonary artery. Three lungs from each group were then fixed in 1% paraformaldehyde and neuroendocrine cells were identified immunohistochemically using antibodies to neuron-specific enolase. As compared to lungs from FA/FA-exposed rats, lungs from SS/SS-exposed rats exhibited 24% lower Cdyn (p = 0.0006, ANOVA), greater reactivity to methacholine (p = 0.0001, repeated measures ANOVA), and more neuroendocrine cells per centimeter basal lamina (p = 0.0006, ANOVA). Lungs from SS/FA- or FA/SS-exposed rats were not different from lungs from FA/FA-exposed rats in any of these parameters. We conclude that exposure to SS both pre- and postnatally (but not only pre- or only postnatally) results in lungs which are less compliant, more reactive to methacholine, and have a greater number of neuroendocrine cells.

Animals↗
PubMed1995

[Effect of ethoxyquin on the utilization of selenium in growing pigs].

In a 2 x 3 factorial arrangement with 30 male castrates (German Landrace; 13.7 +/- 1.7 kg b.w.), after a 2 week feeding period with a maize/torula yeast basal diet poor in selenium and without vitamin E supplementation, the effect of two ethoxiquin concentrations (0 and 150 mg/kg) und 3 selenium concentrations (0.075, 0.10 and 0.125 mg/kg) on growth, the activity of the Se dependent GSH-Px in the erythrocytes and the Se concentrations in liver, kidney, heart and diaphragm was measured after 4 weeks on the experimental diets. Under the experimental conditions chosen ethoxiquin had no effect of any of the parameters studied. Selenium supplementation significantly increased the enzyme activity and the Se concentrations in the organs and tissues analyzed.

Aging↗
PubMed1995

Collagen microbeads: experimental evaluation of an embolic agent in the rete mirabile of the swine.

PURPOSE: To evaluate the histologic and angiographic effects of collagen microbeads as an embolic agent in the swine rete mirabile. METHODS: Human collagen particles (380 +/- 100 microns) of spheroidal shape and smooth surface were used to embolize the rete mirabile in five swine. Control angiograms and pathologic examinations were obtained immediately and sequentially from 3 to 35 days after embolization. RESULTS: The collagen particles were easy to inject through microcatheters. Embolization was always angiographically complete and persistent for at least 5 weeks. Histologic studies showed occlusion of 25% to 50% of the rete vessels. After 3 and 5 weeks' follow-up, transmural and adventitial chronic inflammation was present. Inflammatory infiltrates included lymphohistiocytic cells and scattered eosinophils. The foreign-body giant-cell reaction was pronounced. No evidence of angionecrosis or focal hemorrhage was shown. CONCLUSIONS: Collagen microbeads are a promising experimental embolic agent, with potential future applications in humans.

Animals↗
PubMed1995

[Spatial and age distribution of spermarche and its influence on development of male adolescents in China].

Spatial and age distribution of spermarche, and difference of growth and development in pre- and post-spermarcheal boys were analyzed based on the data of national physique and health surveillance for school children collected in 1991 to study the relationship between spermarche and development. Generally, there existed a trend that onset of spermarche was earlier in boys living in south China than in the north, and earlier in urban than in rural areas. Physique, physiological quality and sports performance were significantly better in post-spermarcheal boys aged 11 to 14 than in pre-spermarcheal ones. Discriminant analysis showed there were significant differences in development between pre- and post-spermercheal boys, especially in body height, weight, biacromial diameter, biiliocristal diameter and vital capacity, but there was no difference in type of body build.

Adolescent↗
PubMed1994

Acetylation of human prostaglandin endoperoxide synthase-2 (cyclooxygenase-2) by aspirin.

Aspirin (acetylsalicylate) treatment of human (h) prostaglandin endoperoxide H synthase (PGHS)-1 expressed in cos-1 cells caused a time-dependent inactivation of oxygenase activity. Aspirin treatment of hPGHS-2 produced an enzyme which retained oxygenase activity but formed exclusively 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE) instead of PGH2. The 15-HETE was exclusively of the 15R configuration. The Km values for arachidonate of native and aspirin-treated hPGHS-2 were about the same suggesting that arachidonate binds to both aspirin-treated and native hPGHS-2 in a similar manner. If, as expected, the formation of 15R-HETE proceeds through abstraction of the 13proS hydrogen from arachidonate, O2 insertion must occur from the same side as the hydrogen abstraction; with all other lipoxygenases and cyclooxygenases, O2 addition is antarafacial. When microsomal hPGHS-2 was incubated with [acetyl-14C]aspirin, the enzyme was acetylated. An S516A mutant of hPGHS-2, which retains enzyme activity, was not acetylated. This indicates that Ser-516 is the site of aspirin acetylation of hPGHS-2; this residue is homologous to the "active site" serine of PGHS-1. An S516N mutant of hPGHS-2 was catalytically active; in contrast, an S516Q mutant lacked cyclooxygenase but retained peroxidase activity. Because in the case of PGHS-1 a smaller asparagine substitution is sufficient to eliminate cyclooxygenase activity, we conclude that the active site of PGHS-2 is slightly larger than that of PGHS-1. An S516M mutant of hPGHS-2 was obtained which resembled aspirin-acetylated hPGHS-2 in that this mutant made 15R-HETE as its major product; however, unlike the aspirin-acetylated hPGHS-2, the Km value of the S516M mutant for arachidonate was 100 times that of native hPGHS-2.

Acetylation↗
PubMed1994

Modulation of oxidant formation in mouse skin in vivo by tumor-promoting phorbol esters.

The pathways of oxidant generation in mouse epidermis were investigated by 32P-postlabeling analysis of diastereomeric DNA adducts derived from oxidation of (7S,8S)-dihydroxy-7,8-dihydrobenzo(a)pyrene ((+)-BP-7,8-diol). The pattern of deoxynucleoside-3'-5'-bis-phosphate adducts in epidermal scrapings from female CD-1 mice indicated that cytochrome P-450 was the major oxidant. When animals were pretreated with the tumor-promoting phorbol ester, tetradecanoyl phorbol acetate (TPA), 24 h before coadministration of TPA and (+)-BP-7,8-diol, the pattern of DNA adducts indicated that peroxyl radicals made a major contribution to (+)-BP-7,8-diol epoxidation. Peroxy radical-dependent epoxidation was maximal when the time between the 2 TPA administrations was 24-72 h. No increase in radical-derived adducts was observed when the non-tumor-promoting phorbol ester 4-O-methyl-TPA was substituted for TPA. The calcium ionophore A23187 stimulated radical generation when substituted for the first, but not the second, TPA treatment. The antiinflammatory steroid fluocinolone acetonide inhibited (-)-anti-BPDE-DNA adduct formation when coadministered with the first but not the second TPA treatment. In contrast, all-trans-retinoic acid inhibited (-)-anti-BPDE-DNA adduct formation when coadministered with the second but not the first TPA treatment. These findings demonstrate that tumor promoting phorbol esters stimulate oxygen radical generation in mouse skin and that radical generation is blocked by inhibitors of tumor promotion.

Animals↗
PubMed1994

Experimental saccular aneurysms. I. Review of surgically-constructed models and their laboratory applications.

Experimental models of intracranial saccular aneurysms are a useful contribution to our basic understanding of these lesions. Currently, the commonest in use are those constructed surgically in laboratory animals. We review the numerous surgical techniques available since the 1950s, and the research applications and uses of experimental aneurysms. Further development and use of such models is greatly encouraged in future pathophysiological, hemodynamic, and therapeutic investigations of intracranial saccular aneurysms.

Animals↗
PubMed1994

Experimental saccular aneurysms. II. A new model in swine.

A new technique for surgical construction of experimental lateral saccular aneurysms on the common carotid artery of swine is described. It involves end-to-side suturing of an isolated segment of vein to an artery. During a short period of parent artery clamping, an elliptical arteriotomy is fashioned through the open-ended vein graft, the open end of which is subsequently tied and clamps are removed to form an aneurysmal vein pouch. The principal advantage of this technique is the short period of vascular clamping necessary to isolate a segment of the parent artery. This prevents severe endothelial injury and prolonged postoperative vasospasm, both of which may promote intra-aneurysmal thrombosis. Narrow- or wide-necked aneurysms can be created. Steps in the surgical construction of this model are detailed, and specific advantages of using swine are highlighted.

Animals↗
PubMed1994

Phospholipid peroxidation in tumor promoter-exposed mouse skin.

We have investigated lipid peroxidation in the skin of CD1 mice following single or repeated topical applications of the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). A substantial accumulation of hydroxyphospholipids, to levels 3-5 times control values, followed exposure to two or more TPA treatments (24-72 h intervals), whereas single applications were ineffective. Sodium borohydride reduction increased the yield of product by approximately 50%, suggesting the additional presence of phospholipid hydroperoxides in the oxidized lipids. Straight phase HPLC analysis of the constituent hydroxy fatty acids, followed by gas chromatography/mass spectrometry, revealed that oxidized derivatives of linoleic acid, including 9- and 13-hydroxyoctadecadienoic acids (9- and 13-HODE), were the primary products. Stereochemical analysis showed ratios of S to R stereoisomers of 1.3 for 13-HODE and 1.27 for 9-HODE, which implied that TPA-induced peroxidation was primarily due to free radical oxidation, although a partial contribution of enzyme (lipoxygenase) activity is possible. The TPA-induced peroxidation was greater in the epidermis than in the dermis. Pre-exposure of mouse skin to the anti-inflammatory agent fluocinolone acetonide, antioxidants and enzyme (phospholipase A2 and lipoxygenase) inhibitors lowered the peroxidation response to subsequent exposure to TPA. Phospholipid peroxidation products may be useful markers of oxygen radical production in TPA-exposed mouse skin with possible relevance to tumor promotion.

Aminobenzoates↗
PubMed1994

[Detection of Epstein-Barr virus DNA in desquamative cell of nasopharyngeal carcinoma by polymerase chain reaction].

In the study, we detected the Epstein-Barr virus (EBV) DNA from thirty-five desquamative cells and four biopsy tissues of the nasopharynx in 35 patients with nasopharyngeal carcinoma using polymerase chain reaction (PCR). Among these patients, 24 had been treated or just began to be treated by 60Co, eleven had finished or nearly finished the treatment. Twelve patients with acute/chronic tonsillitis or pharyngitis served as control. The results showed that the EBV DNA positive rate in patients without treatment or just beginning to be treated was 83.3% (20/24), finished or nearly finished the treatment 9.1% (1/11), biopsy tissues 100% (4/4), and control 8.3% (1/12). The EBV DNA positive rate of the nasopharyngeal carcinoma was significantly higher than the control (P < 0.01). These results indicated that the detection EBV DNA from desquamative cells of the nasopharyngeal carcinoma by PCR is a simple, safe, rapid, specific and sensitive technique. It is useful for making general investigation, primary diagnosis, evaluation of the curative effect of the nasopharyngeal carcinoma.

Base Sequence↗
PubMed1994

An experimental arteriovenous malformation model in swine: anatomic basis and construction technique.

We assessed the feasibility of creating an experimental arteriovenous malformation model in swine by diverting and increasing blood flow through bilateral retia mirabilia. This was achieved by surgical formation of a large right-sided carotid-jugular fistula, in combination with endovascular occlusion of several neck arteries ipsilateral to the fistula. Using this technique, 11 of 13 swine demonstrated an acute-phase angiographic simulation of an arteriovenous malformation. There was rapid circulatory diversion from the left ascending pharyngeal artery ("feeder"), across both retia ("nidus"), and fast retrograde flow into the right ascending pharyngeal and common carotid arteries ("draining vein") toward the fistula. The relevant vascular anatomy of the swine head and neck is outlined, and steps in the construction of this arteriovenous malformation model are detailed.

Anastomosis, Surgical↗
PubMed1994

Experimental models of bifurcation and terminal aneurysms: construction techniques in swine.

We report our preliminary experience in the surgical construction of five experimental bifurcation and terminal aneurysm models in swine. We used unilateral neck vessels to construct models in which the relative directions and sizes of the parent and daughter arteries could be varied by surgery, resulting in aneurysms with high morphologic similarity to human intracranial lesions. Steps in the construction of each model are detailed.

Anastomosis, Surgical↗
PubMed1994

Combined stent implantation and endosaccular coil placement for treatment of experimental wide-necked aneurysms: a feasibility study in swine.

PURPOSE: To assess the feasibility of combining stent implantation in the parent artery with endosaccular coil placement for the treatment of experimentally created wide-necked aneurysms. METHODS: Wide-necked aneurysms were surgically created on the common carotid artery in 12 swine. A metal stent was endovascularly implanted across each aneurysm neck and its effect documented anigiographically. If the aneurysm remained patent, a microcatheter was introduced into the aneurysm through the stent mesh. Electrically detachable coils were delivered into the aneurysm sac to produce thrombosis. RESULTS: After stent implantation, one carotid artery thrombosed and two aneurysms spontaneously occluded. In the other 9 cases, coils were deposited through the stent to occlude the aneurysm. Complete aneurysm packing was possible in all 9 cases. The presence of the stent allowed placement of small coils near the aneurysm neck, thus contributing to the safe occlusion of small remnants in the final stages of aneurysm packing. CONCLUSION: The combination of stent implantation and coil placement is feasible in the treatment of experimental wide-necked saccular aneurysms. The stent maintains patency of the parent artery while allowing aneurysm occlusion by endosaccular coil placement through the stent's mesh. Occlusion of small aneurysm remnants is possible with no fear of coil hernation or migration into the parent artery. Long-term studies will be necessary before application to treatment of selected intracranial aneurysms.

Aneurysm↗
PubMed1994

Biosynthesis of 12(S)-hydroxyeicosatetraenoic acid by B16 amelanotic melanoma cells is a determinant of their metastatic potential.

BACKGROUND: We have previously demonstrated that the metastatic potential of tumor cells can be increased by treatment with exogenous 12(S)hydroxyeicosatetraenoic acid [12(S)-HETE], a lipoxygenase metabolite of arachidonic acid. However, the biosynthesis of the authentic lipid mediator by tumor cells, and especially the correlation of its biosynthesis to tumor cell metastatic capacity have not been characterized. In addition, a role for other mono HETEs in influencing tumor cell metastatic behavior has been suggested, but conclusive evidence is lacking. In this study, we analyzed the biosynthesis of mono HETEs from arachidonic acid in tumor cells of different metastatic ability and correlated biosynthesis to metastatic potential. EXPERIMENTAL DESIGN: The biosynthesis of mono HETEs by low and high metastatic subpopulations of B16 amelanotic melanoma (B16a) cells was analyzed by high performance liquid chromatography (HPLC). The identity of biosynthetic 12-HETE was confirmed by gas chromatography/mass spectrometry (GC/MS) and its stereochemical structure assigned by chiral phase HPLC. The effect of a lipoxygenase inhibitor on the biosynthesis of mono HETEs and its effect on metastatic behavior was examined. RESULTS: HPLC analysis revealed that low (LM180) and high (HM340) metastatic B16a cells exhibited different profiles and efficiencies for conversion of arachidonic acid to mono HETEs. LM180 cells produced equal quantities of 12-HETE and 5-HETE. In contrast, HM340 cells synthesized predominantly 12-HETE and small amounts of 15-, 11- and 5-HETEs. At equal concentrations of substrate, four times more 12-HETE was synthesized by HM340 cells than by LM180 cells. The identity of biosynthetic 12-HETE was confirmed by gas chromatography/mass spectrometry and chiral phase HPLC demonstrated that it was the S enantiomer. The biosynthesis of 12(S)-HETE, but not other HETEs, was significantly inhibited by a lipoxygenase inhibitor, N-benzyl-N-hydroxy-5-phenylpentanamide. N-benzyl-N-hydroxy-5-phenylpentanamide, in a dose-dependent manner, decreased the adhesion of HM340 cells to murine pulmonary microvessel endothelium in vitro and lung colony formation in vivo. Furthermore, re-introduction of 12(S)-HETE, but not other mono HETEs, to HM340 cells pretreated with N-benzyl-N-hydroxy-5-phenylpentanamide, increased their adhesion to endothelium. CONCLUSIONS: Biosynthesis of 12(S)-HETE by tumor cells is a determinant of their metastatic potential and inhibition of 12(S)-HETE biosynthesis in tumor cells may be a crucial target for intervening in metastasis.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1994

Technical feasibility and performance studies of a Doppler guide wire for potential neuroendovascular applications.

PURPOSE: To conduct technical feasibility and performance studies on a new Doppler-tipped, 0.014-inch micro-guide wire for potential neuroendovascular applications. METHODS: In vivo microcatheterizations of brachiocephalic arteries were performed in two swine using the 0.014-inch Doppler guide wire and a commonly used microcatheter. A standardized, bench-top method of evaluating basic mechanical properties of micro-guide wires was also used to compare the 0.014-inch Doppler guide wire with a commonly used micro-guide wire. RESULTS: The 0.014-inch Doppler guide wire had similar steerability, tractability, torque control, and distal tip flexibility to the commonly used micro-guide wire in the in vivo simulations. Frequent micro-guide wire exchanges were possible without loss of superselective positioning of the microcatheter. Bench-top testing showed the 0.014-inch Doppler guide wire to have comparable distal tip flexibility and stiffness to the commonly used micro-guide wire. CONCLUSION: The comparable subjective and objective mechanical properties of the 0.014-inch Doppler guide wire to that of a commonly used micro-guide wire further establishes the possibility of clinical implementation of the device.

Animals↗
PubMed1993

Secretory product expression during Clara cell differentiation in the rabbit and rat.

One function of the nonciliated (Clara) cells of bronchiolar epithelium is to synthesize, store, and release small-molecular-mass (6-12 kDa) secretory proteins or Clara cell secretory protein (CCSP). This study compares the emergence of this secretory function during Clara cell differentiation in rabbits and rats. Lungs of fetal and postnatal animals were evaluated by ultrastructural morphometry and immunohistochemistry. Secretory granules were rarely seen in perinatal animals and increased to adult levels of abundance earlier in rats (1 wk postnatal) than in rabbits (3-4 wk). In contrast, rough endoplasmic reticulum was abundant in perinatal animals and decreased with age. Antibodies raised against CCSP revealed little CCSP in fetal animals; however, after birth CCSP increased to adult levels earlier in rats (1 wk postnatal) than in rabbits (3 wk). We conclude that the maturation of Clara cell secretory function 1) occurs postnatally, 2) involves a decrease in biosynthetic organelles, 3) shows close association between CCSP expression and secretory granule abundance, and 4) varies by species in timing and cellular abundance of biosynthetic machinery.

Animals↗
PubMed1993

[Relationship between the presynaptic depolarization effect of acupuncture and r-aminobutyric acid, opioid peptide and substance P].

The present study was performed on 22 cats to explore whether r-aminobutyric acid (GABA), endogenous opioid peptide and substance P (SP) were involved in the regulation of presynaptic inhibition in acupuncture analgesia. The size of the antidromic compound C action potentials of the sural nerve evoked by the testing stimulation in spinal cord was measured as an indicator of C-afferent terminal excitability. It was found that the electro-acupuncture (EA) at "Huantiao" (GB30) and "Yang lingquan" (GB34) points induced significant enlargement of the antidromic C-waves, showing the depolarization of presynaptic terminals of primary C-afferents was enhanced. The depolarization effect of EA was significantly reduced by bicuculline, naloxone and the antiserum of SP locally applied to the surface of spinal cord respectively. It is supposed that GABA, endogenous opioid peptide and SP may be involved in the regulation of presynaptic inhibition in acupuncture analgesia.

Action Potentials↗