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G Li

Publications and source records attributed to G Li.

At least 541 records · Page 30Linked to original sources
PubMed1998

p53-dependent regulation of nucleotide excision repair in murine epidermis in vivo.

BACKGROUND: p53 protects the integrity of the genome by inducing programed cell death or by promoting DNA repair. We have previously shown that loss or mutation of p53 leads to reduced DNA repair in keratinocytes. OBJECTIVE: The hypothesis that p53 regulates repair of ultraviolet light-induced epidermal DNA damage in vivo was tested in mice. METHODS: An immunohistochemical assay for pyrimidine dimers and 6-4 photoproducts was performed on ultraviolet-irradiated skin from p53 null (-/-) and wild type (+/+) mice. Immunostaining for photoproducts was quantified using computer-assisted imaging. The level of DNA repair was then expressed as the percentage of positive cells remaining as compared to the zero hour time point. RESULTS: p53+/+ mouse skin exposed to 1000 J/m2 retained ' 25% of epidermal cyclobutane dimers at 48 h, whereas approximately 50% remained in p53-/- cells. Using the same UV dose, p53+/+ mice retained 20% of detectable 6-4 photoproducts by 24 h, whereas about 50% remained in epidermal cells of p53-deficient mice. CONCLUSION: Using in situ labelling of UV-damaged cells, we confirm our earlier conclusion that p53 regulates DNA repair within the epidermis after exposure to UV light.

Animals↗
PubMed1998

Prolonged depletion of guanosine triphosphate induces death of insulin-secreting cells by apoptosis.

Inhibitors of IMP dehydrogenase, such as mycophenolic acid (MPA) and mizoribine, which deplete cellular GTP, are used clinically as immunosuppressive drugs. The prolonged effect of such agents on insulin-secreting beta-cells (HIT-T15 and INS-1) was investigated. Both MPA and mizoribine inhibited mitogenesis, as reflected by [3H]thymidine incorporation. Cell number, DNA and protein contents, and cell (metabolic) viability were decreased by about 30%, 60%, and 80% after treatment of HIT cells with clinically relevant concentrations (e.g. 1 microg/ml) of MPA for 1, 2, and 4 days, respectively. Mizoribine (48 h) similarly induced the death of HIT cells. INS-1 cells also were damaged by prolonged MPA treatment. MPA-treated HIT cells displayed a strong and localized staining with a DNA-binding dye (propidium iodide), suggesting condensation and fragmentation of DNA, which were confirmed by detection of DNA laddering in multiples of about 180 bp. DNA fragmentation was observed after 24-h MPA treatment and was dose dependent (29%, 49%, and 70% of cells were affected after 48-h exposure to 1, 3, and 10 microg/ml MPA, respectively). Examination of MPA-treated cells by electron microscopy revealed typical signs of apoptosis: condensed and marginated chromatin, apoptotic bodies, cytosolic vacuolization, and loss of microvilli. MPA-induced cell death was almost totally prevented by supplementation with guanosine, but not with adenosine or deoxyguanosine, indicating a specific effect of GTP depletion. An inhibitor of protein isoprenylation (lovastatin, 10-100 microM for 2-3 days) induced cell death and DNA degradation similar to those induced by sustained GTP depletion, suggesting a mediatory role of posttranslationally modified GTP-binding proteins. Indeed, impeding the function of G proteins of the Rho family (via glucosylation using Clostridium difficile toxin B), although not itself inducing apoptosis, potentiated cell death induced by MPA or lovastatin. These findings indicate that prolonged depletion of GTP induces beta-cell death compatible with apoptosis; this probably involves a direct impairment of GTP-dependent RNA-primed DNA synthesis, but also appears to be modulated by small GTP-binding proteins. Treatment of intact adult rat islets (the beta-cells of which replicate slowly) induced a modest, but definite, death by apoptosis over 1- to 3-day periods. Thus, more prolonged use of the new generation of immunosuppressive agents exemplified by MPA might have deleterious effects on the survival of islet or pancreas grafts.

Animals↗
PubMed1998

Protective effects of ischemic preconditioning on donor lung in canine lung transplantation.

BACKGROUND: Myocardial ischemic preconditioning has been found to protect the myocardium. We hypothesized that lung ischemic preconditioning might enhance canine lung preservation and reduce allograft lung dysfunction after transplantation. METHODS: Ten pairs of adult canines underwent left lung allotransplantation. Five donors were treated with ischemic preconditioning (their left hilus clamped for 10 min and released for 15 min [group IP]), and five donors were not treated with ischemic preconditioning (group C). The donor lungs were flushed with 4 degrees C Euro-Collins solution (ECS) and stored in the same solution for 2 1/2 h, then transplanted to the recipient canines. The animals were observed for 1 to 2 h after transplantation. The lung venous blood of the recipient and donor lung tissue was collected just after thoracotomy and 1 h after reperfusion of the transplanted lung in both groups. RESULTS: The numbers of polymorphonuclear leukocytes (PMNs) in the pulmonary venous blood after reperfusion were significantly higher in group IP than in group C (p<0.05). However, the numbers of PMNs in lung interstitium under microscopy were less in group IP than in group C. The thromboxane B2, malondialdehyde, and mean pulmonary artery pressure contents were significantly lower in group IP than in group C (p<0.05), and the superoxide dismutase and mixed venous oxygen tension values were significantly higher in group IP than in group C (p<0.05). Histologic findings show less damage in group IP than in group C. CONCLUSIONS: The protective effects of ischemic preconditioning in conjunction with ECS flush and storage were superior to using ECS alone. The possible mechanisms were that ischemic preconditioning inhibited the accumulation and activation of PMNs in lung tissue and reduced the production of oxygen-free radicals.

Animals↗
PubMed1998

Definition of extracellular localized epitopes of Hsp70 involved in an NK immune response.

In order to define extracellular localized epitopes of Hsp70 on human tumor cells which are accessible to the immune system, six commercially available Hsp70-specific monoclonal antibodies (mAb) with different recognition sites were examined by immunological approaches. The recognition pattern of these antibodies was analyzed on purified recombinant Hsp70 proteins (rHsp70, Hsc70, DnaK), on lysates of Hsp70-expressing colon carcinoma cells (CX+) and on lysates of M21 rat-1 cells that overexpress human Hsp70 or Hsp70 fragments: ABgl (del 120-428) consisting of the C-terminal part and ASma (del 438-618) consisting of the N-terminal part of human Hsp70. All antibodies reacted equally well with rHsp70 and cytoplasmic Hsp70 derived from human tumor cells or M21 rat-1 cells. Only one antibody (MA3-007; Hsp70, Hsc70) detects a region localized within the ATPase domain of Hsp70 (amino acid 122-264) and reacts positively with the C-terminal deletion mutant ASma. All other antibodies, including RPN1197 are directed against the C-terminal peptide binding domain of Hsp70 and react positively with the N-terminal deletion mutant ABgl. Although all six antibodies detect full-length Hsp70 protein, derived from plasma membrane fractions of CX+ tumor cells, cell surface expressed Hsp70 on viable CX+ tumor cells, as determined by flowcytometry, is only recognized with the antibodies MA3-006 (Hsp70, Hsc70; 504-617), MA3-009 (Hsp70; 504-617) and RPN1197 (Hsp70). An estimation of the ratio of membrane-bound to cytoplasmic Hsp70 molecules revealed that 15-20% of total Hsp70 molecules are expressed on the plasma membrane. This tumor-selective cell surface expression of Hsp70 correlates with an increased sensitivity to lysis mediated by non-MHC restricted natural killer (NK) cells. We demonstrate that only antibodies directed against membrane-bound Hsp70 (MA3-006, MA3-009, RPN1197) inhibit NK-killing activity against Hsp70-expressing tumor cells. Taken together our data indicate that at least the C-terminal region 504-617, that contains at least one single alpha-helix (amino acid 512-536), has to be localized extracellularly and might be of importance for an NK-mediated anti-tumor immune response.

Animals↗
PubMed1998

Molecular cloning and analysis of Ca2+/calmodulin-dependent protein kinase II from the chicken brain.

The goals of this study were to identify specific mRNA for isoforms of calmodulin-dependent protein kinase II in chicken forebrain, prepare a cDNA expression library, and perform a sequence analysis of the kinase cDNA. Specific mRNAs for alpha- and beta-subunits of the kinase were identified in Northern blots. The mRNA for the alpha-subunit is larger in the chicken that in the rat, and for the beta-subunit is smaller in the chicken than the rat. Nucleotide sequencing of selected clones demonstrated the presence of an alpha-subunit with a 33 nucleotide insert known as the alpha-B-isoform. Clones of the beta-subunit showed it to contain a deletion of six nucleotides relative to previously described sequences. Variability in the mRNAs of calmodulin kinase II, as shown here, reflect the presence of species-dependent variability in gene structure as well as the presence of different functional isoforms.

Animals↗
PubMed1998

Injuries to children with attention deficit hyperactivity disorder.

OBJECTIVES: To determine differences between hospital admitted injuries to children with preinjury attention deficit hyperactivity disorder (ADHD) and injuries to those with no preinjury conditions (NO). DESIGN: Comparative analysis, excluding fatalities, of ADHD patients (n = 240) to NO patients (n = 21 902), 5 through 14 years of age. OUTCOME MEASURES: Demographics, injury characteristics, length of stay, admission to the intensive care unit, surgical intervention, disability, and disposition at discharge. DATA SOURCE: Retrospective review of charts submitted by more than 70 hospitals participating in the National Pediatric Trauma Registry between October 1988 and April 1996. RESULTS: Compared with the NO children, the children with ADHD were more likely to be boys (87.9% vs 66.5%), to be injured as pedestrians (27.5% vs 18.3%) or bicyclists (17.1% vs 13.8%), and to inflict injury to themselves (1.3% vs 0.1%). They were more likely to sustain injuries to multiple body regions (57.1% vs 43%), to sustain head injuries (53% vs 41%), and to be severely injured as measured by the Injury Severity Score (12.5% vs 5.4%) and the Glasgow Coma Scale (7.5% vs 3.4%). The ADHD mean length of stay was 6.2 days versus 5.4 in the NO group. In both groups, 40% had surgery, but the ADHD children were admitted more frequently to the intensive care unit (37.1% vs 24.1%). The injury led to disability in 53% of the children with ADHD vs 48% of the NO children. Children with ADHD with any disability were twice as likely to be discharged to rehabilitation/extended care than were the NO children. CONCLUSIONS: Injured children with ADHD are more likely to sustain severe injuries than are children without ADHD. More research is needed to identify prevention efforts specifically targeted at this population.

Adolescent↗
PubMed1998

Expression of BMP-4 mRNA during distraction osteogenesis in rabbits.

We characterized the presence and localization of bone morphogenetic protein 4 (BMP-4) mRNA in the regenerating tissues produced by distraction osteogenesis following tibial osteotomy in the rabbit. The findings are consistent with previous reports on the localization of BMP-4 mRNA expression during fracture repair. The BMP-4 gene is expressed by less differentiated osteoprogenitor cells (fibroblastic mesenchymal cells and preosteoblasts), and not by fully differentiated osteoblasts. BMP-4 gene expression is localized in callus-forming tissue (muscle, periosteum) during callus formation. Our observations suggest that the BMP-4 gene product is one of the local contributing factors in regulating bone and cartilage formation in distraction osteogenesis.

Animals↗
PubMed1998

[Effects of high frequency jet ventilation on respiratory airflow and gas exchange in dogs with inhalation injury].

OBJECTIVE: The experiment was to investigate the effects of respiratory airflow on gas exchange. METHOD: Eight healthy dogs were anesthetized with thiopentone. A 3-D partial dynamic analyzer was used to determine the inspiratory and expiratory flow velocity, and arterial blood samples were collected for blood-gas analysis during spontaneous respiration. Intravenous muscle relaxant was given quickly and the animals were kept apneic and then vapor (105 degrees C) was inhaled for 5 seconds. HFJV was carried out at random under 5 different conditions, each for 20 minutes. Changes in inspiratory velocity (Vi), expiratory velocity (Ve), Reynole's number, PaCO2, PaO2, and PIP were observed. RESULT: 1. During spontaneous respiration, airflow was in form of laminar flow when Re < 1000, and expiratory airflow was either laminar or turbulent when 1000 < Re < 1500. 2. During HFJV, both expiratory and inspiratory airflow were turbulent when Re > 1500. 3. The expiratory velocity with HFTJV increased significantly (P < 0.05). PaCO2 decreased significantly (P < 0.05) compared with HFJV. Obvious negative correlation was found between them (r = -0.9216, P < 0.05), meanwhile inspiratory velocity had an increasing tendency. CONCLUSION: 1. HFJV could maintain normal ventilation of dogs with inhalation injury. The mechanism might be associated with turbulent flow. 2. On the basis of HFJV, HFTJV increases inverse jet airflow, thus the respiratory airflow velocity may be increased and CO2 elimination improved.

Animals↗
PubMed1998

Studies on dynamics of growth and biosynthesis of artemisinin in hairy roots of Artemisia annua L.

Seven hairy root lines with the properties of fast growth and high artemisinin contents were selected from 747 hairy roots induced by transformation of Artemisia annua L. strain 025 with Agrobacterium rhizogenes ATCC15834. The differences of growth rates and artemisinin contents among the 7 selected hairy root lines were extremely significant, of which HR-9 gave the highest yield of artemisinin, reaching 33.25 mg/y.L. The differences of growth rates and artemisinin contents among hairy roots, untransformated roots and callus were also significant. There were no obvious lag phase in batch culture of hairy roots of Artemisia annua L. The exponential growth phase was 7 approximately 15 days after inculation. The growth rate reached the highest on the 11th day, and the cultures reached a stationary phase on the 20th day. The properties of artemisinin content of hairy roots were obviously "related to growth". The artemisinin content decreased slowly during the exponential phase, increased while the growth rate slowed down and remained consistent after the growth stopped. The optimum culture time for hairy roots of Artemisia annua L. was 21 days in our system.

Artemisia↗
PubMed1998

[Antitumorigenic immunocompetence of alveolar macrophages in patients with lung cancer].

OBJECTIVE: The antitumorigenic immunocompetence of alveolar macrophages(AMs) in patients with lung cancer was investigated. METHODS: Twenty-two patients with lung cancer and 18 control subjects underwent bronchoalveolar lavage (BAL) by fiberoptic bronchoscopy to collect BAL fluid (BALF). AMs in the BALF isolated by adherence on plate surface were incubated for 24 hours at 5% CO2, 37 degrees C in medium with or without granunocyte-macrophage colony stimulating factor (GM-CSF). The cell free supernatants (SP) and AMs were harvested, respectively, the activities of nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), superoxide dismutase (SOD), and soluble interleukin 2 receptor in BALF and SP were examined by copper plating cadmium reduction, radioimmunoassay, xanthine-oxidase assay, and ELISA, respectively. mRNA expression of inducible nitric oxide synthase in AMs was detected by reverse transcription-polymerase chain reaction(RT-PCR). RESULTS: (1) The activity of NO was lower in BALF of the tumor-bearing lungs than that of the nontumor-bearing lungs and control groups; the activities of TNF alpha, SOD, and sIL-2R were not statistically significant in BALF between patients with lung cancer and control groups. (2) In supernatants, the activities of NO and TNF alpha were lower in the tumor-bearing lungs than in nontumor-bearing lungs and control groups; sIL-2R concentration of the lung cancers was higher than that of control groups. (3) After AMs were stimulated by GM-CSF, the activities of NO, TNF alpha, and SOD were increased and that of sIL-2R was decreased in SP. (4) mRNA expression of iNOS was demonstrated in AMs of both groups. However, in comparison with beta-actin, the intensity of mRNA expression of iNOS in AMs of lung cancer patients was lower than that of control groups. CONCLUSION: There are some deficiencies in the function of AM at the region of tumors and antitumorigenic immunocompetence in the patients with lung cancer.

Adult↗
PubMed1998

[Protective effects of shenmai cardioplegia on intracardiac operative patients with cardiopulmonary bypass].

Forty intracardiac-operative patients were divided into two groups randomly. Twenty patients were received by the improved St. Thomas Crystal Blood (1:4) Cardioplegia(Group A); 20 by the Shenmai liquid and improved St. Thomas Crystal Blood(1:4) Cardioplegia(Group B). During perioperation, the blood samples and myocardial tissue were collected, and clinical observations were recorded. The results showed that in Group B, contents of myocardial specific isoenzyme of creatine kinase(CK-MB), lactate dehydrogenase(LDH), malonyldialdehyde(MDA), and myocardial Ca2+ were significantly lower, the contents of superoxide dismutase(SOD) were, significantly better than that in Group A; and the histological findings showed less damage in Group B than in Group A. We conclude that Shenmai Cardioplegia can increase the myocardial protection of the intracardiac-operative patients. The possible mechanisms are that Shenmai liquids inhibit the production of oxygen free radicals and calcium paradox.

Adolescent↗
PubMed1998

[The protective effects of cardiac ischemic preconditioning on lung in cardiac operation with cardiopulmonary bypass].

UNLABELLED: Twenty direct vision intracardial operation patients were divided into two groups randomly. After cardiopulmonary bypass, ten patients were treated with myocardial ischemic preconditioning. The aorta were clamped for 3 minutes and released for 3 minutes (Group IP). Another ten patients were not treated with ischemic preconditioning (Group C), only underwent 6 minutes cardiopulmonary bypass. Then the aorta were clamped and intracardial operation were done. The left atrium blood and lung tissue were collected just after thoractomy and half an hour after cardiac reperfusion in both groups. RESULTS: (1) The numbers of polymorphonuclear (PMN) of the two groups were increased significantly after cardiopulmonary bypass (P < 0.01). (2) The number of PMN and SOD, PaO2 contents were significantly higher in Group IP than in Group C (P < 0.05). (3) The numbers of PMN in lung interstitum under microscopy were less in Group IP than in Group C. (4) MDA contents were less in Group IP than in Group C (P < 0.05). (5) Histological finding showed less damage in Group IP than in Group C. It is evident that cardiac ischemic preconditioning could protect lung against ischemia reperfusion injury. The possible mechanisms are that ischemic preconditioning inhibites the accumulation and activation of PMN in lung tissue and reduces the production of oxygen free radicals.

Adult↗
PubMed1998

[Preliminary study on Chlamydia pneumoniae pneumonia].

In order to know the incidence of Chlamydia pneumoniae (strain TWAR) pneumonia and its clinical features, 93 patients with pneumonia and 93 matched patients with non-respiratory diseases were studied. TWAR antibodies (IgG and IgM) were detected by microimmunofluorescence (MIF) test. The results showed that 19.4% (18 cases) patients with pneumonia were TWAR pneumonia, in which 10 cases accompanied by bacteria infection and 7 cases being simple TWAR pneumonia. There were no significant differences in clinical features between TWAR pneumonia and non-TWAR pneumonia, except dry and moist rales. These data showed that the occurrence percentage of TWAR pneumonia in patients with lung cancer was higher than that in patients with the other respiratory diseases. This study suggests that there are TWAR pneumonia in China.

Adolescent↗
PubMed1998

[A study on the activity of nitric oxide in alveolar macrophages from patients with lung cancer].

Nitrite and nitrate (NO2-/NO2-) in the bronchus alveolar lavage fluid (BALF) and the supernatants of incubated alveolar macrophages (AMs) from patients with primary lung cancer were measured by copper-coated cadmium reduction and Griess method. Mrna expression of AM induced nitric oxide synthase (iNOS) were analyzed by RT-PCR. There was NO2-/NO2- in BALF either from lung cancer patients or from control subjects. When compared with control group and the nontumor-bearing lung, the level of NO2-/NO2-was lower in BALF from the tumor-bearing lung [5.18+/-1.1 vs 2.47+/-0.67nmol x mg protein-1 (P< 0.01); 4.65+/- 2.46 vs 2.47+/- 0.67nmol x mg protein-1(P< 0.01)]. We also found a lower level of NO2-/NO2- in the supernatants of incubated AMs from the lung of cancer patients than from control and nontumor-bearing lung [95.03+/- 21.76 vs 63.37+/- 17.58nmol (P< 0.01); 85.61+/- 16.70 vs 63.37+/- 17.58nmol (P< 0.05)]. No significant difference existed between the MRNA expression of AM iNOS in lung cancer patients (69%) and that of control subjects (91%). After the AMs were stimulated with granulocyte-macrophage colony stimulating factor (GM-CSF), the level of NO2-/NO2- in the supernatants was significantly increased (P< 0.01); while the mRNA expression of AM iNOS from patients with lung cancer resulted in an increase of 16.85+/- 7.58% vs 33.38+/- 8.21% of control group (P< 0.05). These observation suggest that some defects of antitumor function occur in the AMs at the tumor region. GM-CSF can stimulate AMs and thus potentiate their NO activity.

Adenocarcinoma↗
PubMed1998

[Research on detection of type C2 staphylococcus enterotoxin in food with piezoelectric immunosensors].

Using the biosensor of immobilization of antibody by Piezoectric Immunosensors (PEI) method, the concentration of antigen was determined. When the concentration of antigen was 10 micrograms/L-2 mg/L, the linear response was found. When the sensor was applied to detect type C2 staphylococcus enterotoxin in food, the method was proved with high specificity and selectivity.

Enterotoxins↗
PubMed1998

[The role of lens epithelium in cataract formation in diabetic rats].

This study was designed to evaluate the changes and the role of lens epithelium in sugar cataract formation, in regard to the fact that the highest level of aldose reductase is found in this layer of lens. By light and electron microscopy, we examined the histological changes of central epithelium in lens of rats made diabetic with streptozotocin (STZ) with or without AL1576, an aldose reductase inhibitor, at varying periods of time ranging from 5 to 40 days after intraperitoneal injection of STZ. Also, we examined Na-K-ATPase activity in lens epithelium of rats with diabetes, diabetes plus AL1576 and normal controls at the time of 30 days. The results showed that the first detectable abnormalities occurred after 15 days of STZ injection and were limited to the lens epithelium; cell edema, intracellular vacuoles and extention of rough endoplasmic reticulum pool were remarkable; that AL1576 could prevent almost all of the lesion mentioned above; and that Na-K-ATPase activity in lens epithelium of rats with diabetes increased at the time of 30 days. The findings suggest that lens epithelium may play an important role in sugar cataractogenesis.

Aldehyde Reductase↗