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Biomedical subjects

H Li

Publications and source records attributed to H Li.

At least 1,315 records · Page 73Linked to original sources
PubMed1997

Inoculation of VacA- and CagA- Helicobacter pylori delays gastric ulcer healing in the rat.

BACKGROUND: Helicobacter pylori is associated with peptic ulcer disease. In the present study, the influence of VacA and CagA- H. pylori on gastric ulcer healing was studied in the rat. METHODS: Twenty-four rats with acetic-acid-induced gastric ulcer were divided into two groups and given either vehicle (Brucella broth) or H. pylori suspension by gavage every 12 h for 7 days. The animals were killed 1 and 8 days after the last H. pylori gavage (i.e. 10 and 17 days after the induction of the ulcer). One hour before death, 3H-thymidine was given intraperitoneally. Tissue samples from the stomach (including the ulcer area) and the duodenum were processed for determination of labelling index and apoptotic cells. RESULTS: Compared with the vehicle-treated controls, the ulcer area in H. pylori-inoculated rats was significantly larger, the epithelial apoptotic cells in the ulcer margin and intact corpus were more numerous, while the cell proliferation of gastroduodenal epithelium was slightly, but not significantly, increased by H. pylori gavage. CONCLUSION: Gastric ulcer healing was delayed after the inoculation of VacA- and CagA- H. pylori in the rat, possibly as a result of excess cell loss by apoptosis.

Acetic Acid↗
PubMed1997

Evidence for a local action of growth hormone in embryonic tooth development in the rat.

Studies in non-dental embryonic tissues have suggested that an interaction between growth hormone and its receptor may play a role in growth and development before the foetal pituitary gland is competent. This study reports the distribution of growth hormone, its receptor and binding protein in developing rat tooth germs from embryonic day 17 to 21 and postnatal day 0 using antibodies specific for each of these proteins. Four foetal rats were processed at each time point (E17, E18, E20/21 and postnatal day 0). Following routine fixation and paraffin embedding, sections were treated with antisera to rat growth hormone, rat growth hormone binding protein and growth hormone receptor. Localization of antibody/antigen complexes was subsequently visualized by addition of biotinylated IgG and reaction with streptavidin peroxidase and diaminobenzidine. Assessment of the level of staining was qualitative and based on a subjective rankings ranging from equivocal to very strong staining. Overall, growth hormone and its binding protein were located both in the cellular elements and throughout the extracellular matrix, whereas the growth hormone receptor showed an exclusively intra-cellular location. All three proteins were detectable in cells of the dental epithelium and mesenchyme at the primordial bud stage (E17) which occurs prior to expression of pituitary growth hormone. At the cap stage of odontogenesis (E18-19), numerous cells in both the dental epithelium and mesenchyme were intensely immunoreactive for growth hormone, its binding protein and receptor. In the succeeding early bell stage (E20-21), most of the mesenchymal cells in the dental pulp were mildly positive for these proteins, while the dental epithelium and adjacent mesenchyme were more immunoreactive. At the late bell stage (postnatal day 0), all three proteins were localized in dental epithelium, differentiating mesenchymal cells the cuspal surface facing the epithelial-mesenchymal interface, preodontoblasts, and odontoblasts forming dentine. From these observations, immunoreactive growth hormone, its receptor and binding protein appear to be expressed in odontogenic cells undergoing histodifferentiation, morphodifferentiation and dentinogenesis in a cell-type and stage-specific pattern throughout embryonic tooth development. This suggests the possibility that growth hormone, or a growth hormone-like protein, plays a paracrine/autocrine role in tooth development in utero.

Animals↗
PubMed1997

Immunotolerance induced by intratesticular antigen priming: expression of TGF-beta, Fas and Fas ligand.

The authors have previously reported that an injection of S-antigen (S-Ag) into rat testes prior to immunization induces systemic tolerance (designated orchidic tolerance) and protects the animals from experimental autoimmune uveoretinitis (EAU) and that the signal for orchidic tolerance induction emigrates from the testis within a few hours after antigen priming of the testis. In order to understand the mechanism by which the signal or signal carrier is generated, they determined in this study changes in immunoreactivity for transforming growth factor-beta (TGF-beta), IFN-gamma, IL-2, Fas and Fas ligand in the testis following an injection of S-Ag. Immunoreactivity for TGF-beta increased with time, reaching a maximum in six hours and declining thereafter. The time required for the maximum expression of TGF-beta coincided well with the time-dependent profile of orchidic tolerance signal generation within the testis. Little or no immunoreactivity was observed for IFN-gamma and IL-2 in normal (control) and S-Ag-injected testes. Immunoreactivity for Fas and Fas ligand was detected both in control and experimental testes and did not change appreciably with time following Ag-priming of the testis. Fas immunoreactivity was found in spermatids and virtually absent in the interstitial tissue, while Fas ligand immunoreactivity was primarily associated with the interstitial cells such as Leydig cells. Fas ligand immunoreactivity was very weak, if any, in the germ cells and Sertoli cells. These results suggest that TGF-beta and Fas ligand expressed in MHC-positive interstitial cells may play an important role in the generation of orchidic tolerance induction signal. A preliminary study showed that splenocytes preincubated with testis extracts and S-Ag, when transferred to naive rats, induced systemic tolerance in recipient animals. Inclusion of anti-TGF-beta or a carboxyl terminal peptide of Fas in the testis extract reduced the potency of incubated splenocytes to induce systemic tolerance in recipient rats. These results indicate that generation of the orchidic tolerance signal does not require the anatomical structure of the testis but is mediated by molecular entities such as TGF-beta and Fas ligand.

Amino Acid Sequence↗
PubMed1997

[A molecular mechanism of retinoblastoma protein (pRB) in neuronal differentiation of PC12 cells].

In order to investigate the molecular mechanism of the retinoblastoma protein, pRB, in neuronal differentiation, the accumulation of the hypophosphorylated pRB in PC12 cells stimulated by nerve growth factor (NGF) was measured by the western blotting method. NGF induced the accumulation of the hypophosphorylated pRB in 30 min. and maximized the level at 12 h. Viral Ki-ras constitutively induced hypophosphorylation of pRB. A dominant negative form of c-Ha-ras suppressed the induction of the hypophosphorylation of pRB by NGF, but not by cAMP. This result is consistent with the idea that NGF induces hypophosphorylation of pRB through the Ras signaling pathway. The reduction of cdk2 activity caused by increment of p21 inhibitor may be a mechanism for hypophosphorylation of pRB. Furthermore, microinjection of a monoclonal antibody for the hypophosphorylated pRB blocked the neurite outgrowth initiated by NGF. It was also found that Hsc 71 interacted with hypophosphorylated pRB in vitro as well as in vivo in neuronal PC12 cells stimulated by NGF. These results suggested the dual role of pRB in the withdrawal of cells from the cell cycle and neuronal differentiation in PC12 cells.

Animals↗
PubMed1997

[Experimental study on the antituberculous activity of ofloxacins].

OBJECTIVE: To compare the antituberculous activities of ofloxacins (OFLX) made by different pharmaceutical companies. METHODS: The minimal inhibitory concentrations (MIC) of OFLX were determined by two-fold dilution method. The efficacy of OFLX was compared in terms of median survival time (ST50) against M. tuberculosis infection in mice. RESULTS: In vitro the activities against M. tuberculosis (H37Rv), M. bovis (Ravenel) and M. Phlei products showed similar degree. The MICs of OFLX were 0.5-1.0 microgram/ml in modified Sauton medium and 1.0 microgram/ml in modified Lowenstin-Jensen medium. OFLX was more active than ethambutol (MIC 4-8 micrograms/ml, 2.0 micrograms/ml, respectively) against M. tuberculosis in the same media. OFLX from domestic or foreign drug companies showed similar results for treating M. tuberculosis infection in mice and all were significantly effective. The efficacy of OFLX at the dose of 4 mg per mouse was found close to that of ethambutol (EMB) at the dose of 2 mg per mouse. The efficacy of OFLX at the dose of 2 mg per mouse close to EMB at the dose of 1 mg per mouse and thiacetazone at the dose of 2 mg per mouse. CONCLUSIONS: In vitro and in vivo, the activities of OFLX from different sources against M. tuberculosis are about the same.

Animals↗
PubMed1997

Effect of tripterine on collagen-induced arthritis in rats.

AIM: To study the therapeutic effect of tripterine (Tri) on collagen-induced arthritis (CIA). METHODS: Collagen type II (Col) 1.5 mg was injected intradermally to induce CIA in rats. Hind paw volumes of rats were measured with a water displacement method. The serum anti-collagen antibody was measured by an enzyme-linked immunosorbent assay. Delayed hypersensitivity was reflected by skin response to Col. Interleukin-1 (IL-1) and interleukin-2 (IL-2) activities were evaluated by [3H]TdR uptake. Joint was evaluated histologically. RESULTS: Tri 15 and 30 mg.kg-1.d-1 given i.g. to rats 3 d after the first sign of arthritis reduced inflammatory swelling, suppressed humoral and skin response to Col, inhibited IL-2 and IL-1 production, reduced pathological progression of joint. CONCLUSION: Tri has a therapeutic effect on CIA.

Animals↗
PubMed1997

[Study on relationship between proto-oncogene expression of c-fos and c-myc in airway, lung tissue and asthma in guinea pigs].

In order to investigate the mechanism of the attack of asthma, the authors examined the proto-oncogene expression of c-fos and c-myc in the airway and lung tissue of the ovalbumin-induced asthmatic guinea pigs by using Dot-blot. Northern-blot and immunohistochemical techniques. There was a baseline expression of c-fos and c-myc in the controls, whereas the mRNA expression of c-fos and c-myc increased much more significantly in asthmatic guinea pigs, it reached maximum at 30 min after the onset of asthma and it was in a time dependant manner. The inducement could be inhibited partially by dexamethasone. Immunohistochemical investigation showed that c-fos and c-myc was distributed mainly in epithelial cells of the airway. The staining was more intensive in the asthmatic guinea pigs than in the controls. The results suggest that the increase in proto-oncogene expression of c-fos and c-myc may be related to the attack of asthma.

Animals↗
PubMed1997

[Effect of extended lymph nodes dissection on curative resection of lung cancer].

We evaluated the effect of extended lymph nodes dissection on curative resection in 386 patients with lung cancer surgically treated for 9 years. The extended lymph node dissection of the hilar and mediastinum was performed on the basis of mapping system for mediastinal lymph nodes developed by Naruke. Altogether 2603 groups of lymph nodes were dissected (mean 6.74 groups). The overall metastatic rate was 49.2% (190/386), including simple N1 diseases (43 cases, 11.1%) and N2 diseases (147, 38.1%). The metastatic rate for squamous cell carcinoma, adenocarcinoma, small cell carcinoma and large cell carcinoma was 30.1%, 44.1%, 48.0% and 50.0%, respectively. The lymphatic metastases in lung cancer showed the features of saltatory infiltration and multiple levels of involvement. Cure could be achieved only after extended dissection of intrapulmonary and mediastinal lymph nodes.

Adenocarcinoma↗
PubMed1997

[Metastases to the mediastinal lymph nodes in lung cancer and their extensive dissection].

OBJECTIVE: To study the metastatic frequency, distribution and feature of mediastinal nodes in lung cancer and to establish criteria for nodal dissection. METHODS: Clinical data of 386 patients who underwent resection of lung cancers in the past 9 years were analyzed retrospectively. Based on the distribution map of mediastinal lymph nodes developed by Naruke, ipsilateral hilar and mediastinal nodes were resected. RESULTS: 147 cases (38.1%) had mediastinal nodal involvement (N2). A total of 289 groups of nodes were dissected. The rate of N2 disease among squamous-cell, adeno-, small-cell and large-cell carcinomas was 30.1%, 44.1%, 48.0% and 50.0%, respectively. In 71 cases with N2 disease in the upper lobes, 146 groups of N2 nodes were resected, including 124 groups in the upper mediastinum (84.9%) and 22 groups in the lower mediastinum (15.1%). In 76 cases with N2 nodes in the lower and middle lobes, 143 groups of N2 nodes were dissected, including 76 groups in the upper mediastinum (53.1%) and 67 groups in the lower mediastinum (46.9%). Saltatory metastases occurred in 79 patients, accounting for 53.7% of N2 nodes and in 16 cases that occurred in the mediastinum (10.9%). CONCLUSION: The feature of mediastinal lymph node metastases in lung cancer may be saltatory and multiple. Cure can be achieved only after extensive dissection of the upper and lower mediastinal nodes.

Adenocarcinoma↗
PubMed1997

[Interactions among stimulators of bone resorption in organ culture].

The labeled 45Ca long bone shafts of 19 day fetal rats in organ culture was used in the study. Actions and interactions between various concentrations of LPS, TNF, LTA and PGE were quantitatively analysed by sample channels ratio method. The results indicated that they could all induce bone resorption in organ culture and show significance of differences assessed using student's test (P < 0.05). Interacts between LPS and TNF, LPS and PGE, TNF and PGE were greater than the sum of the individual responses when added together (the expection value), LPS and LTA, TNF and LTA were equal to the expection value, but LTA and PGE were less than the expection value. The result supported that the interactions among these stimulators of bone resorption were important in the pathogenesis of bone loss in periodontal disease.

Animals↗
PubMed1997

Non-trans-scleral suture fixation of posterior chamber intraocular lenses in the absence of posterior capsular support.

PURPOSE: To develop a new technique for fixation of posterior chamber intraocular lens (IOL) in the absence of posterior capsule support. MATERIALS AND METHODS: We performed non-trans-scleral fixation of intraocular lenses on 24 cases (24 eyes) without posterior capsule support. Two scleral flaps with limbal incisions and two peripheral iridectomies were made at 1 o'clock and 7 o'clock positions respectively. A suture-leading needle was used to lead the prolene suture from the limbal incision and iridectomy on one side through the iridectomy and limbal incision on the other side. Intraocular lens (IOL) was then fixed in the ciliary sulcus. RESULTS: After a mean follow-up of 6.6 months (range from 3 to 14 months), corrected visual acuity of 16 cases (16 eyes, 66.7%) got 0.5 or better. Postoperative complications included discoria (4 eyes), surface membrane formation (1 eye), choroidal detachment (1 eye) and tilt of IOL (1 eyes), but all were not severe. CONCLUSION: In some situations such as low intraocular pressure, non-penetration scleral fixation may be a good way to implant IOL in the absence of posterior capsule support.

Adolescent↗
PubMed1997

[The developement of a new torque experiment device for biomaterials].

This paper introduces a biomaterial torque experiment apparatus which consists of AST486 computer, photodiode array, code device interface circuit, and magnetoelectric motional coil structure. According to experimental conditions, the computer sends out signal to the coil which under the magnetic field is activated to produce a series of desired torque and bring the sample to deflect. Angular displacement is measured by photodiode array and code device system. The whole system has good dynamics and high precision and could finish a series of torque experiment for biomaterials, and AST486 computer can automatically conduct signals analyzing and data processing.

Biocompatible Materials↗
PubMed1997

Evidence of increased endogenous carbon monoxide production in newborn rat endotoxicosis.

Carbon monoxide is thought to serve as a new endogenous mediator in the pathogenesis of sepsis and septic shock. In newborn rat endotoxicosis, carbon monoxide levels in the circulation as well as liver, kidney and lung were found to be significantly increased (P < 0.05). Moreover, the elevations of carbon monoxide correlated with enhanced nitric oxide production as indicated by nitrite/nitrate levels (P < 0.05). Our present data showed for the first time that endogenously produced carbon monoxide was increased during the course of shock-like states, which suggested that the role of carbon monoxide in sepsis and septic shock might worth further study.

Animals↗
PubMed1997

Hypersensitivity of cashew nut.

Cashew nut hypersensitivity can cause severe reactions even life threatening. In the past few years, there are more cases of cashew nut allergy than before in Beijing. Thirty patients with cashew nut allergy were analyzed in this paper. Case history, skin test, specific IgE and oral blinded challenge were used in the diagnosis.

Adult↗
PubMed1997

[In vivo and in vitro metabolism of tricyclopinate hydrochloride in the rat].

The metabolism of tricyclopinate hydrochloride(TCPN), a new anticholinergic agent, was studied by in situ perfused rat liver preparation. Two metabolites were isolated by HPLC. Metabolite I was identified as an N-demethylation product, while metabolite II was shown to be an arylhydroxylation product. Metabolite I and metabolite II were also isolated from the urine of the rat given TCPN i.g. This result shows that the two metabolites from the perfused rat liver are just the final metabolites produced in vivo. The metabolites in rat liver microsomes were also identified as those just described. These results suggest that the biotransformation reaction of TCPN is mainly catalyzed by the enzyme in rat liver microsomes. The results of experiment on receptor activity indicate that the action potency with mAChR of metabolite I and metabolite II was only 1/20 and 1/50, respectively, of that of TCPN.

Animals↗