Biomedical subjects

N Li

Publications and source records attributed to N Li.

At least 253 records · Page 14Linked to original sources

PubMed1999

[Biological mechanism of macrophage activation by wear particles at the bone-implant interface].

OBJECTIVE: To observe the response of membrane Ca(2+) channel of macrophage-like cells (MCs) to wear particles and analyze the cytoplasmic [Ca(2+)]i change in macrophage activation at the bone-implant interface. METHODS: The synoviocyte system of normal hip joint was established in vitro. Immunohistochemical technique (SABC) with CD68 Mab was used to differentiate MCs and fibroblast-like cells (FCs) in the system, and the time when MCs begin to perform phagocytosis was determined by SEM. 1.5 mg/ml (W/V) Ti alloy, Co-Cr alloy or UHMWPE particles suspension was added into the system to monitor the [Ca(2+)]i change in the MCs by confocal laser scanning microscope (CLSM). RESULTS: Phagocytosis of MCs happened after 6 hours, but within 1 hour the Ca(2+) channel of their cell membrane opened for 1 - 6 times and caused rapid and transient pulses of [Ca(2+)]i in cytoplasm after different period of incubation. There was no significant difference between times or range of the [Ca(2+)]i pulse (P > 0.05). The group of UHMWPE particles had the longest incubation period (P < 0.05), but the interval of pulses was shorter than that in the group of Co-Cr alloy particles (P < 0.05). [Ca(2+)]i pulses still appeared when MCs were incubated by indomethecin (P > 0.05), but the phenomenon could be blocked by nimodipin. CONCLUSIONS: Activation of macrophages at the bone-implant-interface could happen before they phagocytose wear particles. The primary switch-on mechanism of osteolysis mediated by cytokines at the bone-implant interface may be the opening of membrane Ca(2+) channel and pulse-like Ca(2+) influx of macrophages when stimulated by wear particles.

Biocompatible Materials↗

PubMed1999

[Early use of Chinese drug rhodiola compound for patients with post-trauma and inflammation in prevention of ALI/ARDS].

OBJECTIVE: To evaluate the effects of the Chinese drug rhodiola on the preventive treatment of acute lung injury (ALI) caused by post-traumatic/inflammatory and thoracic-cardiovascular operations. METHODS: 104 patients who coincide with their diagnosis and standard scale were divided randomly in to single number groups A(1), B(1), C(1) and D(1) (early preventive treatment group EG) and double number groups A(2), B(2), C(2) and D(2) (control group CG). The treatment of primary disease both in EG and CG was similar, but in EG four grams of rhodiola compound (RCO) were used every day for a period of 3-15 days since admission and 5-7 days after operation. The indicators related to ALI in each groups were measured. RESULTS: PaO(2), AaDO(2) and hemorheology were significant in EG than in CG (P < 0.05) or (P < 0.01). The complication rate of ARDS was decreased about of 50.0% in EG than in CG. CONCLUSIONS: Early use of RCO may protect against major risk factors of ALI/ARDS caused by massive trauma/infection and thoracic-cardio-operations.

Adolescent↗

PubMed1999

[Apoptosis of small intestinal epithelial cells in small intestinal allograft rejection].

OBJECTIVE: To investigate apoptosis of epithelial cells during small intestinal allograft rejection in rats. METHODS: Heterotopic small intestinal transplantation was performed with inbred rat F344/N (RT1(l)) and inbred rat Wistar/A (RT1-A(k), RT1-E(d)). All recipients were divided into four groups: group I, nonoperative control (Wistar); group II, isograft control (Wistar-->Wistar); group III, allograft (F344-->Wistar); group IV, treatment control [F344-->Wistar + Cyclosporine A (6 mg x kg(-1) x d(-1))]. The grafts were harvested on day 3, 5, 7 after operation. All graft samples were subjected to histological examination and apoptotic cells of graft epithelial cells with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). RESULTS: Histologically mild acute rejection occurred on day 3 after operation in group III, moderate acute rejection on day 5 after operation, severe acute rejection on day 7 after operation. But none of group II had the histological evidence of acute rejection and the histological evidence of group IV indicated that Cyclosporine A could effectively controlled small intestinal acute allograft rejection. The TUNEL showed that the number of apoptotic cells per crypt in group III was significantly higher than that of the other three control groups on day 3 and day 5 after operation (P < 0.01). The epithelial mucosa in group III completely sloughed on day 7 after operation. CONCLUSIONS: Apoptosis plays an important role in small intestinal allograft rejection. Detection of apoptotic cells with TUNEL could be a valuable tool for the diagnosis of small intestinal allograft rejection.

Animals↗

PubMed1999

[The effects of n-3 fatty acid, fructose-1, 6-diphosphate and glutamine on mucosal cell proliferation and apoptosis of small bowel graft after transplantation in rats].

OBJECTIVE: To evaluate the effects of n-3 fatty acid (n-3 FA), fructose-1, 6-diphosphate (FDP) and glutamine (GLN) on mucosal cell proliferation and apoptosis of small bowel graft. METHODS: 196 inbred strain Wistar rats underwent heterotopic small bowel transplantation (SBT) as donors and recipients respectively. n-3FA, FDP and GLN were given via gastrolavage as well as venous infusion within total parenteral nutrition (TPN) solution for 10 days before and after surgery. Flow cytometry and in situ cell death detection were used for analysing the changes of mucosal cell proliferation and apoptosis. RESULTS: Fewer proliferation and more apoptosis took place in mucosal cells of small bowel graft after transplantation. A higher mucosal cell proliferative index and lower apoptotic index were found in all small bowel graft after supplying with n-3FA, FDP and GLN. CONCLUSIONS: n-3FA, FDP and GLN specific nutritional support significantly promoted mucosal cell proliferation, and on the other hand inhibited mucosal cell from undergoing apoptosis with different degrees. The effects of regulation help improve the structure and absorption function of transplanted small bowel.

Animals↗

PubMed1999

[Effect of wear particles on cell-to-cell communication of synoviocyte system in vitro and its significance in aseptic loosening of prosthesis].

OBJECTIVE: To study the biological reason of abnormal fiber proliferation at bone-implant interface of aseptically loosened prosthesis by observing cell-to-cell communication of synoviocyte system in vitro under the stimulation of wear particles. METHODS: The synoviocyte system of normal human hip joint was established in vitro and the change of cell-to-cell communication was monitored by fluorescence redistribution after photobleaching technique (FRAP) and confocal laser scanning microscope (CLSM) after Ti alloy, CoCr alloy or UHMWPE particles suspension (1.5 mg/ml, W/V) was added into the system. RESULTS: Cell-to-cell communication of synoviocyte system significantly decreased under the stimulation of three kinds of particles (P < 0.01). he decreased degree was maximal in UHMWPE group and minimal in Ti alloy group (P < 0.01). The cell-to-cell communication level of fibroblast-like-cells (FCs) was significantly lower than that of macrophage-like-cells (MCs) (P < 0.05). CONCLUSIONS: Besides the effect of cytokines promoting fiber proliferation, the great amount of fibrous granuloma at bone-implant interface which has relations with aseptic loosening may be caused by the decrease of cell-to-cell communication of fibroblast under direct stimulation of wear particles.

Alloys↗

PubMed1999

[Posttraumatic or inflammatory acute respiratory distress syndrome on high altitude area: a retrospective analysis of 94 deaths due to ARDS/MOF].

OBJECTIVE: To determine the characteristic predictors of acute respiratory distress syndrome (ARDS) in the high altitude area of China. METHODS: According to the diagnostic criteria of ARDS, 2 325 cases were screened in the recent 10 years. Except malignant tumors, cardio-cerebrovascular diseases, chronic obstructive pulmonary disease, and chronic multiple organ failure, the causes of death were analysed retrospectively. RESULTS: 94 cases (4.04%) were diagnosed as ARDS, but in the primary case record, only 27 cases (1.16%) had been diagnosed as ARDS/MOF. Of the 94 ARDS patients, 79 complicated by extrapulmonary organ damage involving the kidney, heart, liver, gastro-intestinal tract, and brain. A total of 305 organs were involved (average 3.24 organs each case). Lung failure only accounted for 15 cases. CONCLUSIONS: The combination of the diagnostic criteria of ARDS for high altitude area and flate area, injury severity scale, blood gas monitoring, and integrated traditional Chinese medicine and western medicine may improve the prognosis of ARDS.

Adolescent↗

PubMed1999

[Protect intercellular communication of pigment epithelium after laser photocoagulation].

OBJECTIVE: To observe the protective effect on the intercellular communication of retinal pigment epithelial (RPE) cells of dexamethasone (Dex) and verapamil (Ver) at different concentrations after laser photocoagulation. METHOD: Ten pig eyes were used to culture pig pigment epithelium cells. Use different concentrations of Dex and Ver to incubate cultured RPE cells 2 hours before laser coagulation, and then measure the intercellular communication function of confluent cells surrounding the coagulation spots after photocoagulation. RESULT: 125 mg/L Dex and 20 mg/L Ver could protect the intercellular communication of RPE cells under laser photocoagulation. The high concentration of drugs had better result. CONCLUSION: Both Dex and Ver can preserve the intercellular communication in vitro. The protective capacity is related to the concentration of drug.

Animals↗

PubMed1999

[The satisfaction, efficacy, and relative factors for Norplant in countryside of Sichuan].

A total of 1473 Norplant users in the countryside of Sichuan Province were investigated to present a multivariate analysis of satisfaction, side effect, and efficacy for Norplant. The results showed that contraceptive efficacy rate, continuation rate, prevalence rate of side effects and satisfactory rate were 99.3%, 90.6%, 86.4%, and 69.7%, respectively. The logistic regression analysis showed that the variables significantly contributing to satisfaction were the user's knowledge about Norplant, the user's voluntary choice of Norplant, and the spouse's satisfaction. The satisfaction was associated with continuation and the prevalence of side effects. It is concluded that Norplant is efficacious and satisfactory to a certain extent among the users in rural Sichuan; its continuation rate is high but the prevalence of side effects is noticeable. For the wide application of Norplant in the countryside, it is important to strengthen propagation and education.

Adult↗

PubMed1999

[The value of diagnosis with technetium-99m sequential scintigraphy of parotid gland in Sjögren's syndrome].

OBJECTIVE: To explore the value of diagnosis with 99mTcO4- sequential scintigraphy of parotid gland in Sjögren's syndrome. METHODS: Technetium-99m(99mTcO4-) sequential scintigraphy was used in 52 cases of Sjögren's syndrome. RESULTS: The results were analysed quantitatively with activity curve by using ROI computer program. 46 cases (88.46%) were parotid swelling. The contour was clear in 28 cases (53.85%) and blurred in 18 cases (34.62%). The function of parotid was normal in 7 cases (13.46%), parotids with light damage in 15 cases (28.84%), parotids with middle damage in 17 cases (32.69%), and parotids with serious damage in 13 cases (25%). Most cases of damaged secretary function was present in the early phase, and a few cases of damaged absorption function was found in the following process. CONCLUSION: 99mTcO4- sequential scintigraphy of parotid gland is greatly valuable to diagnosis of Sjögren's syndrome.

Adult↗

PubMed1999

[Industrial scale-up of continuous ethanol fermentation using yeast flocs].

Inducing yeast cells to self-flocculate as a cell immobilization method, an industrial scale-up plant composed of 4 air-lift suspended-bed bioreactors in parallel and with a total volume of 400 m3 was established and operated. During a more than 6 months continuous operation, the effluent contained ethanol of 70-80 g/L and residual sugar less than 5 g/L and the ethanol productivity of 7-8 g/L.h-1 was achieved.

Bioreactors↗

PubMed1999

[Analysis of T cell subgroup in children with allergic rhinitis].

OBJECTIVE: To observe the different distribution of T cell in peripheral blood between normal children and children with allergic rhinitis. METHOD: We use the indirect immunofluorescence to make a statistical analysis randomly in 16 children with allergic rhinitis and 20 in control group. RESULT: CD3, CD4, CD8 in peripheral blood of patients are a lot less than those in normal children. CONCLUSION: The change of T cell subgroup's distribution is an important process of immune mechanism disturbance and can be used as a monitoring standard in allergic diseases.

Adolescent↗

PubMed1999

[The utilization of bronchoalveolar lavage in children].

OBJECTIVE: To investigate the clinical effect of bronchoalveolar lavage (BAL) in children with atelectasis owing to pulmonary infection. METHOD: We compared the preactive period in test group (87 cases) who were treated by BAL with control group (30 cases) who were treated by conventional drug. RESULT: The result showed a shorter preactive period in test group than that of control group (P < 0.01). No significant difference of effect of treatment was found between this two groups (P > 0.05). CONCLUSION: Under directly visual metal bronchoscope, we can improve the ventilation function by eliminating the obstructions, and can fasten the absorption and recovery of the foci by using antibiotics locally. So BAL can obviously shorten the course of treatment. Due to the structure defect, using of BAL with fiber bronchoscope is restricted in children. However, metal bronchoscope under total anesthesia can provide a good operation condition which include a large ventilation cavity and a wider visual field, so it has high clinical value in children.

Adolescent↗

PubMed1998

Expression and characterization of human PDEdelta and its Caenorhabditis elegans ortholog CEdelta.

Cyclic GMP phosphodiesterase (PDE) is rod photoreceptor disk membrane-associated via C-terminal lipid tails. PDEdelta, a recently identified subunit, was shown to disrupt PDE/membrane interaction under physiological conditions, without affecting PDE catalytic activity. We found that a PDEdelta ortholog from the eyeless nematode Caenorhabditis elegans (termed CEdelta) solubilizes bovine PDE in vitro with an EC50 very similar to PDEdelta. Immobilized PDEdelta and CEdelta both bind, in addition to bovine PDE, an N-terminal fragment of human retinitis pigmentosa GTPase regulator, but not rhodopsin kinase and Ran binding protein 1. The results suggest that PDEdelta and CEdelta may regulate membrane binding of a variety of proteins in photoreceptors and other tissues.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1998

Secondary structure of antifreeze proteins from overwintering larvae of the beetle Dendroides canadensis.

Antifreeze proteins from overwintering larvae of the beetle Dendroides canadensis are among the most active antifreeze proteins known. The Dendroides AFPs (DAFPs) consist of 6 or 7, 12- or 13-mer repeat units with a consensus sequence of -C-T-X3-S-X5-X6-C-X8-X9-A-X11-T-X13-. Nearly all of the Cys residues are in internal disulfide bridges between positions 1 and 7 within the repeats. The study presented here identified the secondary structure of the DAFPs using infrared and circular dichroism (CD) spectroscopies. The eight disulfide bridges impose significant constraints on potential secondary structural features (i.e., a number of three-residue gamma-turns) which may lead to unusual infrared and CD spectra that require special interpretation. At 25 degreesC the DAFPs contain approximately 46% beta-sheet, 39% turn, 2% helix, and 13% random structure. In the presence of ice there is a slight increase in helix and beta-sheet structures and a decrease in both turn and especially random structures. This change in the presence of ice may reflect a certain amount of flexibility in the DAFP structure. These structural changes may permit an improved lattice match between the DAFPs and ice, a requisite for the noncolligative freezing-point-depressing activity of the DAFPs.

Amino Acid Sequence↗

PubMed1998

The conducting form of gramicidin A is a right-handed double-stranded double helix.

The linear pentadecapeptide antibiotic, gramicidin D, is a naturally occurring product of Bacillus brevis known to form ion channels in synthetic and natural membranes. The x-ray crystal structures of the right-handed double-stranded double-helical dimers (DSDH) reported here agree with 15N-NMR and CD data on the functional gramicidin D channel in lipid bilayers. These structures demonstrate single-file ion transfer through the channels. The results also indicate that previous crystal structure reports of a left-handed double-stranded double-helical dimer in complex with Cs+ and K+ salts may be in error and that our evidence points to the DSDH as the major conformer responsible for ion transport in membranes.

Amino Acid Sequence↗

PubMed1998

Ionizing radiation and short wavelength UV activate NF-kappaB through two distinct mechanisms.

We examined the mechanisms by which two different types of photonic radiation, short wavelength UV (UV-C) and gamma radiation, activate transcription factor NF-kappaB. Exposure of mammalian cells to either form of radiation resulted in induction with similar kinetics of NF-kappaB DNA binding activity, nuclear translocation of its p65(RelA) subunit, and degradation of the major NF-kappaB inhibitor IkappaBalpha. In both cases, induction of NF-kappaB activity was attenuated by proteasome inhibitors and a mutation in ubiquitin-activating enzyme, suggesting that both UV-C and gamma radiation induce degradation of IkappaBs by means of the ubiquitin/proteasome pathway. However, although the induction of IkappaBalpha degradation by gamma rays was dependent on its phosphorylation at Ser-32 and Ser-36, UV-C-induced IkappaBalpha degradation was not dependent on phosphorylation of these residues. Even the "super repressor" IkappaBalpha mutant, which contains alanines at positions 32 and 36, was still susceptible to UV-C-induced degradation. Correspondingly, we found that gamma radiation led to activation of IKK, the protein kinase that phosphorylates IkappaBalpha at Ser-32 and Ser-36, whereas UV-C radiation did not. Furthermore, expression of a catalytically inactive IKKbeta mutant prevented NF-kappaB activation by gamma radiation, but not by UV-C. These results indicate that gamma radiation and UV-C activate NF-kappaB through two distinct mechanisms.

Antibodies↗

PubMed1998

A 69-base pair fragment derived from human transcobalamin II promoter is sufficient for high bidirectional activity in the absence of a TATA box and an initiator element in transfected cells. Role of an E box in transcriptional activity.

A 69-base pair (bp) (-581/-513) fragment derived from human transcobalamin II distal promoter constructed upstream of a chloramphenicol acetyltransferase reporter gene demonstrated high bidirectional promoter activity in transfected epithelial Caco-2 cells. DNase I footprinting, gel mobility shift, supershift, and mutagenesis studies with the 69-bp fragment demonstrated that a GC box (-568/-559) and an E box (-523/-528), which interacted with Sp1/Sp3 and USF1/USF2 (where USF is upstream stimulatory factor), respectively, were required for the full transcriptional activity of this fragment. Whereas mutations in the GC box reduced the promoter activity by 50%, mutations in the E box alone or in both the E box and GC box resulted in 90% loss of transcriptional activity. The essential role of the E box in the bidirectional promoter activity was further demonstrated by transient transfection in Caco-2, K-562, and HeLa cells using a 29-bp (-541/-513) fragment that contained only the E box. Based on these results we suggest that 1) the E box is essential for both the GC box-dependent and -independent promoter activity of the 69-bp fragment, 2) cooperative interactions between Sp1/Sp3 and USFs are required for the full activation of the 69-bp promoter activity, and 3) the single E box is able to mediate bidirectional transcription in transfected cells in the absence of an obvious TATA box or a known initiator element.

Base Sequence↗

PubMed1998

Characterization of the human transcobalamin II promoter. A proximal GC/GT box is a dominant negative element.

Deletion and mutagenesis of the 5'-flanking region of the human transcobalamin II (TC II) transfected in human intestinal epithelial Caco-2 cells have revealed that TC II promoter activity is: (a) very weak; (b) restricted to a core region (-29 to -163) that contained multiple transcription initiation sites; (c) not dependent on other potential elements, such as a distally localized CCAAT box, a CF1, a HIP1 binding motif and a MED-1 element; (d) modulated weakly by a positive-acting GC box (-568-GAGGCGGTGC) and strongly by a proximal GC/GT overlapping box (-179 CCCCCGCCCCACCCC). Gel shift and immunosupershift analyses demonstrated that both the positive-acting GC box and the negative-acting GC/GT box were recognized by Sp1 and Sp3. Co-transfection studies using Sp1 and/or Sp3 expression plasmids revealed that while Sp1 stimulated, Sp3 repressed Sp1-mediated transactivation of TC II transcription. The proximal GC/GT box also acted as a negative element in human chronic myelogenous leukemia K-562 and HeLa cells. These results suggest that tissue/cell specific expression of the TC II gene may be controlled by the relative ratios of Sp1 and Sp3 that bind to the GC/GT box and the weak promoter activity of TC II is due to the transcriptional repression caused by the binding of Sp3 to the proximal GC/GT box.

Base Sequence↗