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Biomedical subjects

Lei Li

Publications and source records attributed to Lei Li.

At least 217 records · Page 12Linked to original sources
PubMed2003

Olfactory input increases visual sensitivity in zebrafish: a possible function for the terminal nerve and dopaminergic interplexiform cells.

Centrifugal innervation of the neural retina has been documented in many species. In zebrafish Danio rerio, the only so-far described centrifugal pathway originates from terminal nerve (TN) cell bodies that are located in the olfactory bulb. Most of the TN axons terminate in the forebrain and midbrain, but some project via the optic nerve to the neural retina, where they synapse onto dopaminergic interplexiform cells (DA-IPCs). While the anatomical pathway between the olfactory and visual organs has been described, it is unknown if and how olfactory signals influence visual system functions. We demonstrate here that olfactory input is involved in the modulation of visual sensitivity in zebrafish. As determined by a behavioral assay and by electroretinographic (ERG) recording, zebrafish visual sensitivity was increased upon presentation of amino acids as olfactory stimuli. This effect, however, was observed only in the early morning hours when zebrafish are least sensitive to light. The effect of olfactory input on vision was eliminated after lesion of the olfactory bulbs or after the destruction of DA-IPCs. Intraocular injections of a dopamine D(2) but not a D(1) receptor antagonist blocked the effect of olfactory input on visual sensitivity. Although we cannot exclude the involvement of other anatomical pathways, our data suggest that the TN and DA-IPCs are the prime candidates for olfactory modulation of visual sensitivity.

Amino Acids↗
PubMed2003

Molecular anatomy of the DNA damage and replication checkpoints.

Cell cycle checkpoints are signal transduction pathways that enforce the orderly execution of the cell division cycle and arrest the cell cycle upon the occurrence of undesirable events, such as DNA damage, replication stress, and spindle disruption. The primary function of the cell cycle checkpoint is to ensure that the integrity of chromosomal DNA is maintained. DNA lesions and disrupted replication forks are thought to be recognized by the DNA damage checkpoint and replication checkpoint, respectively. Both checkpoints initiate protein kinase-based signal transduction cascade to activate downstream effectors that elicit cell cycle arrest, DNA repair, or apoptosis that is often dependent on dose and cell type. These actions prevent the conversion of aberrant DNA structures into inheritable mutations and minimize the survival of cells with unrepairable damage. Genetic components of the damage and replication checkpoints have been identified in yeast and humans, and a working model is beginning to emerge. We summarize recent advances in the DNA damage and replication checkpoints and discuss the essential functions of the proteins involved in the checkpoint responses.

Animals↗
PubMed2003

Imaging diagnosis of pancreato-biliary diseases: a control study.

AIM: To evaluate the clinical value of various imageological methods in diagnosing the pancreato-biliary diseases and to seek the optimal procedure. METHODS: Eighty-two cases of pancreato-biliary diseases confirmed by surgery and pathology were analyzed. There were 38 cases of cholelithiasis, 34 cases of pancreato-biliary tumors and 10 other cases. The imageological methods included B-US, CT, ERCP, PTC, cross-sectional MRI and MR cholangiopancreatography (MRCP). RESULTS: The accuracy rate of MRCP in detecting the location of pancreato-biliary obstruction was 100%. In differentiating malignant from benign obstruction, the sensitivity of the combination of MRCP and cross-sectional MRI was 82.3%, the specificity was 93.8%, and the accuracy rate was 89.0%. The accuracy rate for determining the nature of obstruction was 87.8%, which was superior to that of B-US (P=0.0000) and CT (P=0.0330), but there was no significant difference between direct cholangiopancreatography and the combination of MRCP and conventional MRI (P=0.6666). CONCLUSION: In most cases, MRCP can substitute direct cholangiopancreatography for diagnosis. The combination of MRCP and cross-sectional MRI should be considered as an important means in diagnosing the pancreato-biliary diseases, pre-operative assessment and post-operative follow-ups.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2003

[Analysis of protein phosphorylation by combination of IMAC, phosphatase with biological mass spectrometry].

Protein phosphorylation is the most important reversible post-translational modification in cells. Analysis of phosphorylated proteins and identification of their phosphorylation sites is helpful for understanding their biological functions. MALDI-TOF-MS and ESI-Q-TOF-MS play important roles in protein phosphorylation analysis. In this work, immobilized metal affinity chromatography (IMAC) was used to selectively enrich phosphopeptides from protein digest mixtures, and treatment of phosphopeptides with alkaline phosphatase was used to confirm the phosphorylation. Finally, the phosphorylation sites were determined by tandem mass spectrometry analysis and database searching.

Chromatography, Affinity↗
PubMed2003

[Risk factors for stroke in Chinese with non valvular atrial fibrillation: a case-control study].

OBJECTIVE: The aim of this study is to identify the risk factors in Chinese with nonvalvular atrial fibrillation and stroke, using case-control methodology. METHODS: A total of 4 511 adult patients diagnosed with atrial fibrillation were identified from 18 hospitals over a 2-year period. There were 1 086 patients with rheumatic valvular atrial fibrillation and 3 425 patients with nonvalvular atrial fibrillation. Among the nonvalvular atrial fibrillation patients, 827 had ischemic stroke. The data of the patients having nonvalvular atrial fibrillation with stroke was compared with those having nonvalvular atrial fibrillation without stroke (n = 2 598). The effect of each variable on stroke was assessed with a logistic regression analysis. RESULTS: The studied cases with stroke and controls without stroke were similar in terms of percentage with sex, a past history of congestive heart failure, myocardial infarction, and mean left atrial size. Cases were significantly older than controls (73.3 +/- 9.2 vs. 68.2 +/- 12.3, P < 0.001) and more likely to have a history of hypertension (71.0% versus 51.6%, P < 0.001) and diabetes (17.9% vs. 11.1%, P = 0.001). There is strong evidence that left atrial (LA) thrombi make AF patients highly risky for stroke. In multivariate analysis, age > or = 75 (OR 1.76; 95% CI 1.08 approximately 2.98), history of hypertension (OR 1.52; 95% CI 1.28 approximately 1.80), diabetes (OR 1.39; 95% CI 1.11 approximately 1.76), high systolic blood pressure (OR 1.71; 95% CI 1.21 approximately 2.28), LA thrombi (OR 2.77; 95% CI 1.25 approximately 6.13) were independently associated with stroke. The lack of the association between left ventricular dysfunction and stroke is due to the relatively incorrect diagnosis of heart failure in the context of atrial fibrillation. CONCLUSIONS: Our analysis suggests that old age, hypertension, diabetes, high systolic blood pressure and LA thrombi detected with echocardiography are independent risk factors, which should be considered when decision of long-term anticoagulation therapy to prevent stroke with nonvalvular atrial fibrillation is to be made.

Adolescent↗
PubMed2003

[Effect of severe thoracic trauma combined with endotoxin challenge on phagocytosis function of alveolar macrophages and pulmonary interstitial macrophages].

OBJECTIVE: To observe the difference of phagocytosis between alveolar macrophages and pulmonary interstitial macrophages, and to investigate their responses to severe thoracic trauma with or without lipopolysaccharide (LPS) challenge. METHODS: A rat model of severe thoracic trauma was reproduced by thoracic impact machine. The alveolar macrophages and interstitial macrophages were isolated before injury and at 2, 4, 8, 16, 24 hours after injury respectively. The dynamic changes of these macrophage phagocytosis were tested by malachite green colorimetry. RESULTS: Macrophage phagocytosis function was increased during the early stage after trauma (2 and 4 hours) and then decreased. The phagocytosis function of alveolar macrophages was stronger than that of interstitial macrophages in all time points before and after trauma. After challenge with LPS, no further significant effect on the alveolar macrophages was found, while LPS challenge could stimulate the phagocytosis of interstitial macrophages. CONCLUSION: Alveolar macrophages and pulmonary interstitial macrophages are functional heterogeneous, and their response to trauma and combined with endotoxin challenge are different. The results indicate that the two subgroups of macrophages play different roles in immune function disorder after trauma.

Animals↗
PubMed2003

[An experimental study of inhibiting effect of decoy oligodeoxynucleotides on the gene expression of collagen in NIH3T3 cell].

OBJECTIVE: To investigate the effect of activator protein-1 (AP-1) decoy-oligodeoxynucleotides (Decoy-ODNs) on the expression of fibroblast alpha2 type I collagen, so as to explore the gene therapy of pathologic scar. METHODS: Decoy-ODNs targeting AP-1 were designed and synthesized. NIH3T3 cells were transfected by cationic liposomes. The distribution of Decoy-ODNs in the cells was investigated. The inhibiting effects of Decoy-ODNs on AP-1 were determined by electrophoretic mobility shift assay (EMSA). And the effects of Decoy-ODNs on the collagen synthesis in the cells were analyzed by RT-PCR. RESULTS: AP-1 Decoy-ODNs could competitively inhibit the AP-1 in vitro activity. Cationic liposomes could play roles by effectively transfecting Decoy-ODNs into the plasma and nucleus. The mRNA expression of fibroblast alpha2 type I collagen decreased evidently after 24 hours of Decoy-ODNs action. CONCLUSION: Decoy-ODNs could inhibit the mRNA expression of fibroblast alpha2 type I collagen by antagonizing AP-1.

Animals↗
PubMed2003

[Dynamics of the pest and natural enemy communities in peach orchards].

Investigations on structure of arthropod community in peach gardon were conducted with the principal component analysis, the optimal sorting method and fuzzy clustering analysis. The results showed that more obvious main factors and temporal patterns exist in the community. Dealing with the population dynamics of 55 species of arthropods by fuzzy clustering analysis and taking lambda = 0.47, we divided the community into four stages. The number of pests and their natural enemies was divided into three parts by the optimal sorting method. The dominant species of pests and their natural enemies were demonstrated by the principal component analysis.

Animals↗
PubMed2003

New emergy indices for sustainable development.

The emergy indices for the evaluation of system's sustainable development ability were studied. Results indicated that the emergy indices are simplified and merged, and a new emergy index for sustainable development (EISD) is deduced. Employing EISD, two cases are conducted. The first one is to compare three different dike-pond agro-ecological engineering modes, which are: melon-melon-cabbage-four domestic fishes (mode I), melon-melon-cabbage-pig-four domestic fishes (mode II) and melon-melon-cabbage-pig-four domestic fishes combined with Siniperca chuatsi B. (mode III). The result is that the EISD of mode I is 0.53. Mode II's EISD is 5.26 times of mode I, and mode III's EISD is 6.83 times of mode I. The second one is to evaluate the development of Zhongshan City, Pearl Delta, during 1996 to 2000. The result indicated that the EISD of Zhongshan had appreciably declined from 1996 to 1998, and quickly improved from 1998 to 2000, partly because of its environment protection and product construction. Both of the two cases studies showed that EISD can assessment the sustainable development ability more roundly, with the consideration of environmental impact and social-economic effect at the same time.

China↗
PubMed2003

Mutation analysis of potassium channel genes KCNQ1 and KCNH2 in patients with long QT syndrome.

OBJECTIVE: To determine mutations of two common potassium channel subunit genes KCNQ1, KCNH2 causing long QT syndrome (LQTS) in the Chinese. METHODS: Thirty-one Chinese LQTS pedigrees were characterized for mutations in the two LQTS genes, KCNQ1 and KCNH2, by sequencing. RESULTS: Two novel KCNQ1 mutations, S277L in the S5 domain and G306V in the channel pore, and two novel KCNH2 mutations, L413P in the transmembrane domain S1 and L559H in the transmembrane domain S5 were identified. The triggering factors for cardiac events developed in these mutation carriers included physical exercise and excitation. Mutation L413P in KCNH2 was associated with the notched T wave on ECGs. Mutation L559H in KCNH2 was associated with the typical bifid T wave on ECGs. Mutation S277L in KCNQ1 was associated with a high-amplitude T wave and G306V was associated with a low-amplitude T wave. Two likely polymorphisms, IVS11 + 18C > T in KCNQ1 and L520V in KCNH2 were also identified in two LQTS patients. CONCLUSIONS: The mutation rates for both KCNQ1 (6.4%) and KCNH2 (6.4%) are lower in the Chinese population than those from North America or Europe.

Asian People↗
PubMed2003

[A change in antigen presentation ability of spleen macrophage from Balb/c mouse during late pregnancy].

OBJECTIVE: To study the antigen presentation ability of spleen macrophage from Balb/c mouse during late gestation. METHODS: The spleen of Balb/c mouse during late gestation was collected aseptically and macrophage was separated; the mice in estrus were used as control. The ability of macrophage to prime original T cells to human gamma globulin antigen (HGG-Ag) or placenta antigen (Pla-Ag) was evaluated by a delayed-type hyper sensitivity (DTH) response induced by the same antigen, and the ability of macrophage to induce the proliferation of primed normal T cells to HGG-Ag or Pla-Ag was assessed by an antigen special lymphocyte transformation in vitro. RESULTS: After being sensitized previously by spleen macrophage from Balb/c mice during late gestation that has been pulsed by HGG-Ag or Pla-Ag, the DTH intensity of mice response to the same antigen was significantly weaker than that being sensitized by macrophage from mice in estrus (P < 0.05). When spleen macrophage from Balb/c mice during late gestation was used as antigen presentation cell (APC), the proliferability of primed T cell induced by HGG-Ag or Pla-ag was significantly lower than that when macrophage from estrous Balb/c mouse was used in vitro (P < 0.05). CONCLUSION: The antigen presentation ability of spleen macrophage from Balb/c mouse is inhibited during late pregnancy. This may be the important mechanism by which maternal immune system tolerates embryo antigen and may be responsible for the down-regulation of maternal cell mediated immunity during pregnancy.

Animals↗
PubMed2003

Prevention and treatment of hepatitis B recurrence after liver transplantation.

OBJECTIVE: To study the efficacy of liver transplantation on end-stage hepatitis B related liver diseases, and the prevention and treatment strategies of hepatitis B recurrence after the transplantation. METHODS: The efficacy of combined treatment of lamivudine and hepatitis B immune globulin (HBIG) therapy on 24 patients who had received liver transplantation was retrospectively studied. RESULTS: All the 24 patients with end-stage hepatitis B-related liver diseases treated with lamivudine alone or combined therapy of lamivudine and HBIG showed normal liver function and 21 of them lost hepatitis B virus (HBV) markers. However, the remaining 3 patients became HBsAg positive again soon after liver transplantation. CONCLUSIONS: Liver transplantation is effective for patients with end-stage hepatitis B-related liver diseases. Combined treatment of lamivudine and HBIG may prevent the recurrence of hepatitis B after the operation.

Adult↗
PubMed2003

[A molecular epidemiological study on the human immunodeficiency virus infection in Jiangsu province].

OBJECTIVE: To identify subtypes of human immunodeficiency virus 1 (HIV-1) strains and their distribution, infection sources, and the trends of HIV infection in Jiangsu province. METHODS: Anticongulated bloods from 46 infected persons were collected to separate previrus DNA. HIV-1 env genes were then amplified by nested-PCR and sequenced for their C2-V3 region so as to identify subtypes. The analysis of consensus sequence, genetic distance and phylogenetic tree were conducted with GCG software. RESULTS: By the end of 2001, there had been six subtypes of HIV-1 strains identified in Jiangsu province: A, B, B', C, D and E. The predominant subtypes were C (accounting for 40.48%) and B' (accounting for 38.10%). Subtype C accounted for 86.67% among injecting DUs while subtype B' accounted for 91.67% among commercial blood donors and receivers. CONCLUSION: Subtype B'among commercial blood donors was brought to Jiangsu from neighboring provinces. The outbreak of HIV-1 infection among local DUs was caused by subtype C from Xinjiang province. Findings from HIV/AIDS molecular epidemiologic study suggest that it is challenging for Jiangsu to treat patients, apply vaccine, prevent and control AIDS in the future.

China↗
PubMed2003

[Three-dimentional distribution pattern dynamics of Erythroneura sudra and its natural enemy Erigonidum graminicola].

Investigations on the Erythroneura sudra and Erigonidum graminicola populations in three layers (upper, middle and lower) and four directions (east, south, west and north) of peach tree crown showed that both of them had aggregated spatial distributions in these 7 part, because 5 parameters used to analyze the distribution reached required standard. Each insect was attracted by the others, as the parameter (alpha) in Iwao formulation m* = alpha + beta x - (1971) was positive. The average density of aggregation was the biggest in its middle layer and east direction, and the smallest in its lower layer and south direction. The biggest average density of aggregation appeared in mid-September.

Animals↗
PubMed2003

[Progress in locked nucleic acid research].

Locked nucleic acid (LNA) is a novel oligonucleotide analogue in which 2'-O and 4'-C positions in the b-D-ribofuranosyl ring are joined via an O-methylene, S-methylene or amino-methylene moiety, locked in a C3'-endol3E north (N)-type furanose conformation. LNAs posses many properties, such as extraordinarily high hybridize affinities for complementary DNA/RNA sequences, remarkable antisense activity, nuclease resistance, good aqueous solubility and none detactable toxicity, et al. LNAs is a most promising molecule for development of diagnostics and therapeutics. For example, apply LNAs to single--nucleotide polymorphisms genotyping, telomerase activity have been efficiently suppressed by LNA oligomers, efficient cleavage of highly structured RNA has been achieved using LNA-modified DNAzymes (LNAzymes), and so on.

Animals↗
PubMed2002

Src kinase mediates phosphatidylinositol 3-kinase/Akt-dependent rapid endothelial nitric-oxide synthase activation by estrogen.

17beta-Estradiol activates endothelial nitric oxide synthase (eNOS), enhancing nitric oxide (NO) release from endothelial cells via the phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway. The upstream regulators of this pathway are unknown. We now demonstrate that 17beta-estradiol rapidly activates eNOS through Src kinase in human endothelial cells. The Src family kinase specific-inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) abrogates 17beta-estradiol- but not ionomycin-stimulated NO release. Consistent with these results, PP2 blocked 17beta-estradiol-induced Akt phosphorylation but did not inhibit NO release from cells transduced with a constitutively active Akt. PP2 abrogated 17beta-estradiol-induced activation of PI3-kinase, indicating that the PP2-inhibitable kinase is upstream of PI3-kinase and Akt. A 17beta-estradiol-induced estrogen receptor/c-Src association correlated with rapid c-Src phosphorylation. Moreover, transfection of kinase-dead c-Src inhibited 17beta-estradiol-induced Akt phosphorylation, whereas constitutively active c-Src increased basal Akt phosphorylation. Estrogen stimulation of murine embryonic fibroblasts with homozygous deletions of the c-src, fyn, and yes genes failed to induce Akt phosphorylation, whereas cells maintaining c-Src expression demonstrated estrogen-induced Akt activation. Estrogen rapidly activated c-Src inducing an estrogen receptor, c-Src, and P85 (regulatory subunit of PI3-kinase) complex formation. This complex formation results in the successive activation of PI3-kinase, Akt, and eNOS with consequent enhanced NO release, implicating c-Src as a critical upstream regulator of the estrogen-stimulated PI3-kinase/Akt/eNOS pathway.

Adenoviridae↗
PubMed2002

Selective recruitment of TAFs by yeast upstream activating sequences. Implications for eukaryotic promoter structure.

The general transcription factor TFIID is composed of the TATA box binding protein (TBP) and multiple TBP-associated factors (TAFs). In yeast, promoters can be grouped into two classes based on the involvement of TAFs. TAF-dependent (TAF(dep)) promoters require TAFs for transcription, and TBP and TAFs are present at comparable levels on these promoters. TAF-independent (TAF(ind)) promoters do not require TAFs for activity, and TAFs are either absent or present at levels far below those of TBP on these promoters. Here, we demonstrate that the upstream activating sequence (UAS) mediates the selective recruitment of TAFs to TAF(dep) promoters. A TAF(ind) UAS fails to recruit TAFs and to direct efficient transcription when inserted upstream of a TAF(dep) core promoter. This transcriptional defect can be overcome by a potent activator, indicating that a strong activation domain can compensate for the absence of TAFs on a TAF(dep) core promoter. Our results reveal a requirement for compatibility between the UAS and core promoter and thus help explain previous reports that only certain yeast UAS-core promoter combinations and mammalian enhancer-promoter combinations are efficiently transcribed. The differential recruitment of TAFs by UASs provides strong evidence for the proposal that in vivo TAFs are the targets of some, but not all, activators.

Promoter Regions, Genetic↗