Biomedical subjects

Lei Li

Publications and source records attributed to Lei Li.

At least 181 records · Page 10Linked to original sources

PubMed2004

Activin A and betacellulin: effect on regeneration of pancreatic beta-cells in neonatal streptozotocin-treated rats.

Activin A and betacellulin (BTC) are thought to regulate differentiation of pancreatic beta-cells during development and regeneration of beta-cells in adults. In the present study, we used neonatal rats treated with streptozotocin (STZ) to investigate the effects of activin A and BTC on regeneration of pancreatic beta-cells. One-day-old Sprague-Dawley rats were injected with STZ (85 micro g/g) and then administered for 7 days with activin A and/or BTC. Treatment with activin A and BTC significantly reduced the plasma glucose concentration and the plasma glucose response to intraperitoneal glucose loading. The pancreatic insulin content and beta-cell mass in rats treated with activin A and BTC were significantly increased compared with the control group on day 8 and at 2 months. Treatment with activin A and BTC significantly increased the DNA synthesis in preexisting beta-cells, ductal cells, and delta-cells. The number of islet cell-like clusters (ICCs) and islets was significantly increased by treatment with activin A and BTC. In addition, the number of insulin/somatostatin-positive cells and pancreatic duodenal homeobox-1/somatostatin-positive cells was significantly increased. These results indicate that, in neonatal STZ-treated rats, a combination of activin A and BTC promoted regeneration of pancreatic beta-cells and improved glucose metabolism in adults.

Activins↗

PubMed2004

Salivary adenocarcinoma, not otherwise specified: a collection of orphans.

CONTEXT: Salivary adenocarcinoma, not otherwise specified, refers to gland-forming malignancies that do not satisfy the diagnostic requirements of other "named" malignancies. OBJECTIVE: To review the features of 11 patients with salivary adenocarcinoma, not otherwise specified. To also compare the diagnostic frequencies of 2 databases, one from the Mount Sinai Medical Center (New York, NY), the other from the Shanghai Ninth People's Hospital (Shanghai, People's Republic of China). DESIGN: Pathology files were searched to establish a database of salivary tumors. All available hematoxylin-eosin- stained slides from the resection specimens diagnosed as either adenocarcinoma, not otherwise specified, or with vague or unusual diagnoses (eg, probable carcinoma-ex-pleomorphic adenoma) were pulled from our files and reexamined. Dates of death were confirmed with the Social Security Death Index. RESULTS: We identified 11 patients with salivary adenocarcinoma, not otherwise specified, ranging in age from 49 to 80 years (median, 67 years), with a male preponderance. The parotid gland was the most common site of tumor origin. Ten of these tumors were high grade, and 1 was intermediate grade. Two patients were diagnosed at stage II, while the remaining patients were diagnosed at stage III or IV. Histologically, all tumors were invasive, with variable glandular differentiation and diverse architectural patterns. The diverse cytologic tumor cell types included cuboidal, columnar, epithelioid, polygonal, oncocytoid, clear, melanoma-like, mucinous, sebaceous, and plasmacytoid. Four patients died after 4 to 27 months (mean, 15 months), 1 patient is alive with disease at 12 months, 1 patient is disease-free at 14 years, and 3 patients remain disease-free after short follow-ups (10, 12, and 12 months). One patient had surgery just recently, and the remaining patient had no follow-up. CONCLUSIONS: Salivary adenocarcinoma, not otherwise specified, is an aggressive, high-grade malignancy, with a predisposition for the parotid gland. It is characterized by cytologic and architectural diversity and an invasive growth pattern.

Adenocarcinoma↗

PubMed2004

[Clinical application of anterior cervical locking plate systems and analysis of complications as well as their countermeasures].

OBJECTIVE: To summarize the methods and skills of anterior cervical locking plate systems in clinical application and to analyze the causes of some complications as well as give some preventive or remedial countermeasures. METHODS: From 1998 to 2002, 159 patients with cervical spondylotic myelopathy, fracture-dislocation, tumor or tuberculosis of the cervical spine were treated with anterior locking plate systems. The complications were reviewed and analyzed. RESULTS: Ten kinds of complications related to anterior locking plate systems occurred in 21 patients. Most of the complications were caused by improperly-selecting implants, experience and technique deficiency. CONCLUSION: The important preventive or remedial countermeasures are correctly-selecting patients, meticulous preoperative preparation, properly-selecting implants, standard and skillful manipulation and rational postoperative protection.

Adult↗

PubMed2004

[Spectrum of ST-T-wave changes in hereditary long-QT syndrome in Chinese].

OBJECTIVE: To evaluate the spectrum of ST-T-wave patterns in Chinese patients with hereditary long-QT syndrome. METHODS: ECGs of 61 families were studied to determine ST-T-wave patterns. Genotypes were identified by sequencing. RESULTS: 32 cases showed similarity to LQT1, 41 to LQT2 and 2 to LQT3 in ECG, and 3 cases could not be classified. QTc of the patients with symptom was (0.547 +/- 0.08) sec and that of the patients without symptoms was (0.526 +/- 0.06) sec, both were much longer than that of normal members of the families. T wave patterns were different in 48 cases at different time. QTc difference in a same person between two times or DeltaQTc were as follows: (0.048 +/- 0.057) sec in patients and (0.023 +/- 0.017) sec in normal members (P < 0.001). 12 cases of LQT1 and 11 cases of LQT2 were identified by genotype sequencing. CONCLUSIONS: There are some differences in ST-T waves between these Chinese hereditary long-QT syndrome patients and European and American patterns. These patients showed greater variability in ST-T wave pattern including the changes in the same type, in the same pedigree and in the same patients at different time.

Adolescent↗

PubMed2004

[The mutation scanning of KCNQ1 gene for 31 long QT syndrome families].

OBJECTIVE: To search for the mutations of potassium voltage-gated channel, KQT-like subfamily member 1(KCNQ1) gene in 31 Chinese long QT syndrome(LQTS) families. METHODS: Due to the genetic heterogeneity, the genotype of patients was first predicted based on the spectrum of ST-T-wave patterns on ECG. Ten of 31 probands were considered as LQT1. Then the mutation of KCNQ1 gene was screened by the polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) technique combined with DNA sequencing in all members of these 10 families. To avoid omitting some LQT1 patients without typical characteristics and also to do methodological comparison, the mutations of KCNQ1 gene on 16 exons were screened by PCR and direct DNA sequencing in the rest 21 non-LQT1 probands only. Co-segregation analysis was carried out after the finding of an abnormal sequence. In case that the abnormality existed in patients only, the test of such exon was performed in 50 irrelevant normal individuals. RESULTS: Two missense mutations and three single nucleotide polymorphisms (SNPs) were found in the LQT1 predicted families. The two mutations were S277L (1 family) and G306V (1 family) in exon 5 and were not reported previously. Three polymorphisms were 435C-->T (7 families), 1632C-->A (1 family), and IVS1+9 C-->G (3 families). Only a splice mutation IVS1+5G-->A (2 families) and a polymorphism IVS10+18C-->T (1 family) were found in the non-LQT1 predicted probands. All three mutations were localized within the functional domain of KCNQ1 and were co-segregated with the disease, and were not found in 50 normal individuals. CONCLUSION: Two novel missense mutations, 1 splice mutation and four SNPs on KCNQ1 gene were found in the 31 LQTS families. Combined with ECG-based genotype prediction, PCR-SSCP could find most mutations on KCNQ1 and be a simple and economic method for screening LQTS.

Adolescent↗

PubMed2004

[Cloning and identification of NF-kappaB p50 Rel homology domain and detection of its autonomous reporter gene activity].

AIM: To clone NF-kappaB p50 Rel homology domain (RHD) gene and construct the "bait" vector in yeast two-hybrid system, and detect the yeast cell toxicity and autonomous reporter gene activity of target gene. METHODS: Total RNA was extracted from human peripheral blood mononuclear cells and NF-kappaB p50 RHD gene was amplified by RT-PCR, and cloned into pGBKT7. The recombinant plasmid was transformed into yeast AH109. The growth condition of the transformants was observed in the selected medium SD/-Trp. The reporter gene activity of target gene in the yeast cells was verified by filter blotting. RESULTS: Using restriction enzyme digestion analysis and PCR, the length of inserted gene was confirmed correct. Sequencing result indicated that the sequence of the inserted gene and its open reading frame were completely correct, and then the recombinant plasmid was named pGBKT7-p50. p50 RHD gene had neither autonomous reporter gene activity nor yeast cytotoxicity. CONCLUSION: As a bait plasmid, pGBKT7-p50 could be used in yeast two-hybrid system to screen and capture the polypeptides which interact with p50 RHD.

Cloning, Molecular↗

PubMed2004

[Effect of grape procyanidins on the apoptosis and mitochondrial transmembrane potential of thymus cells].

OBJECTIVE: Investigating the effect of grape procyanidins(GPC) on the apoptosis and mitochondrial transmembrane potential of thymus cells damaged by H2O2. METHODS: Thymus cells of mouse were cultured in vitro. The cells were pretreated by GPC and then damaged by 125 mumol/L H2O2 for two hours. The levels of apoptosis and mitochondrial transmembrane potential were analysed by flow cytometry. RESULTS: Apoptosis rate and the level of mitochondrial transmembrane potential of positive group were (29.53 +/- 3.8)% and 27.24 +/- 2.2 (D value) respectively. After pretreatment of 50 mg/L GPC, the levels of apoptosis and mitochondrial transmembrane potential were (8.61 +/- 1.2)% and 87.55 +/- 4.7(D value). The differences between the two groups were significant (P < 0.05). CONCLUSION: GPC can inhibit apoptosis and decrease of mitochondrial transmembrane potential of thymus cells damaged by oxygen free radical.

Animals↗

PubMed2004

[The role of myeloid differential protein-2 in innate immunity].

As typical PRRs (pattern-recognition receptors), TLRs (Toll-like receptors) play an important role during innate immunity recognition. MD-2 (myeloid differential protein-2) may contain distinct functional domains that can separately and simultaneously bind TLRs (TLR4 or TLR2) and TLR ligands, such as lipopolysaccharide (LPS). The special structure of MD-2 may result in its three main functions: (1) An association with TLR4 that amplifies TLR4 responsiveness to ligands, especially LPS. (2) Enabling TLR2-mediated responses to LPS and enhancing TLR2-mediated responses to bacteria and their cell wall components. (3) Increasing the expression of TLR2 and TLR4 and possibly influencing the correct intracellular distribution of TLR4. Importantly, while MD-2 regulation of TLR expression and distribution is well established, determining whether the interaction is direct or not will require further study. Thus, MD-2 is not only an assistant molecule of TLR4 but is also a key regulatory molecule in innate immunity, and may play important roles during infection, inflammation, immune responses and many other pathologic and physiologic processes.

Animals↗

PubMed2004

[Geostatistic analysis on spatial patterns of Aphis gossypii and Erigonidium graminicola].

The spatial structure and spatial correlativity of Aphis gossypii and Erigonidium graminicola populations during different periods were investigated by geostatistic methods. The results showed that the semivariogram of A. gossypii appeared as spherical type, indicating its spatial pattern was an aggregated type with a range of 7.33-12.40 cm, while that of E. graminicola was also fitted into spherical model, indicating an aggregated spatial arrangement with a range of 6.47-20.88 cm. The amount and spatial distribution of E. graminicola were closely related to those of A. gossypii, suggesting that E. graminicola was the dominant natural enemy influencing A. gossypii population.

Animals↗

PubMed2004

[De novo salivary malignant myoepithelioma: pathologic diagnosis of 19 cases].

OBJECTIVE: To study the pathological characteristics of salivary malignant myoepithelioma with characteristic multinodular architecture. METHODS: To observe the histologic and cytologic characteristics of 19 cases of de novo salivary malignant myoepithelioma with multinodular growth pattern. Immunohistochemistry of calponin, SMA, S-100, GFAP, cytokeratin, PCNA was done on 11 cases and ultrastructure was observed on 3 cases. RESULTS: 19 tumors presented characteristic multinodular growth pattern, mostly accompanied by central necrosis. Neoplastic nests invaded the surrounding normal tissue and tumor cells displayed a variety of pleomorphism. Epitheliod cell was the most predominant cell type. Tumor-related extracellular matrix formation was revealed among tumor cells. Immunohistochemical staining demonstrated that the tumor cells were positive for calponin, SMA, S-100, GFAP, AE1/AE3, CKH and PCNA. Myofilaments were found in neoplastic cell cytoplasm under the electron microscope. CONCLUSION: Histologic and cytologic observation, immunostaining and ultrastructural study all supported the myoepithelial and malignant nature of the tumor.

Diagnosis, Differential↗

PubMed2004

[Change in Toll-like receptor 4 expression on interstitial macrophages in acute lung injury].

OBJECTIVE: To observe changes in the level of Toll-like receptor 4 (TLR4) mRNA and the expression of TLR4 protein in interstitial macrophages in serious thoracic injury. METHODS: A rat model of severe thoracic trauma was reproduced,then interstitial macrophages were isolated and collected by enzymatic digestion before and after trauma cultured. TLR4 mRNA and the expression of TLR4 protein were measured by Northern and Western blotting before trauma and 2, 4, 8, 16, 24 hours after trauma. RESULTS: A stable and reliable severe thoracic trauma model was successfully reproduced with 400 kPa impact on the up-right chest of rat by a multiple-function collision apparatus. The expression was up-regulated by trauma and the highest expression of interstitial macrophages occurred 8, 16 hours after the trauma, and returned to normal range at 24 hours. CONCLUSION: The up-regulation of TLR4 might participate in the pathological process of excessive inflammation after trauma to the lung.

Acute Lung Injury↗

PubMed2004

[Seasonal dynamics of arthropod community diversity, evenness and relative stability in peach orchards].

This study showed that the diversity index of total arthropod community in peach orchards was significantly correlated to the diversity index of both phytophages (r = 0.9480) and predators sub-communities (r = 0.7855), and the two sub-communities were correlative (r = 0.6741). It was also significantly correlated to the evenness index of total community (r = 0.7870), but not correlated to the evenness index of both sub-communities. The diversity index (H') of total community was significantly correlated to the ratio of predators individuals (Sd) and phytophages individuals (Sz) (r = 0.8112) and of species (Ss) and individuals (Si) (r = 0.9188), but not correlated to the ratio of predators (Spl) and phytophages (Szl).

Animals↗

PubMed2004

[Clustering analysis and optimal cut-apart of arthropod community in megranate orchard].

Based on the principles of community ecology and by the method of fuzzy clustering, this paper studied the temporal and quantitative dynamics of the arthropod community and sub-community in megranate orchard, aimed to utilize natural enemy resources for pests control. The results showed that both of total community and natural enemy sub-community could be grouped into 4 clusters, and non-natural enemy sub-community could be grouped into 3 clusters. This clustering reflected the complexity of the community structure. The optimal cut-apart could divide the total community and sub-community into 3 stages, i. e., April-August, September-October, and November.

Animals↗

PubMed2004

[Studies on relationship between peak capacity and column length for separation of peptides by high performance liquid chromatography].

In the study of proteomics, the high efficiency separation of peptides is very important for the identification of proteins and their interactions. Therefore, the relationship between peak capacity and column length for the separation of peptides on two reversed-phase columns with different lengths by reversed-phase high performance liquid chromatography was investigated and the effect of gradient times on peak capacity and peak width was examined. The experimental results showed that column length has significant effect on peak capacity. Furthermore, longer gradient times increase not only the peak number, but also the peak width, which is very favorable for the detection of more complicated mixture of peptides when they are separated and identified by capillary liquid chromatography combined with tandem mass spectrometry.

Chromatography, High Pressure Liquid↗

PubMed2004

[Study on the spectroscopy and electrochemistry of the combination between samarium (III) ion probe and bovine serum albumin].

The synthesis of solid compound of bovine serum albumin (BSA) with samarium (III) ion was studied. The FTIR spectrum shows that samarium (III) ion forms high sensitivity compound with BSA's oxygen in hydroxyl and nitrogen in amidocyanogen or amide groups. The ultraviolet spectrum shows that samarium (III) ion binds directly with residue of tyrosine. The character of the combination between samarium (III) ion and BSA was studied under simulated physiology conditions. The fluorescence spectrum shows that the molar ratio of samarium (III) ion to BSA is 2.5:1, with apparent complex constant lgK = 11.00. By cyclic voltammetry, the paper reports the stability of compound of BSA with samarium (III) ion and the effect pH on the of combination between samarium (III) ion and BSA.

Animals↗

PubMed2004

[Synthesis and spectral properties of L-amino acid tailed porphyrin and their zinc(II) complexes].

Three new L-amino acid tailed porphyrins and their zinc(II) complexes were synthesized by L-amino acid and 5-[o-(bromnoethoxyl)phenyl]-10,15,20-triphenyl prophyrin. FABMS, UV-Vis, IR, elemental analysis and chemical analysis were used to determine the structures of these porphyrins and their zinc complexes. The FTIR spectra (4000-400 cm(-1)) of L-amino acid tailed porphyrin and its zinc(II) complexes were measured and investigated. The major bands have been empirically assigned in comparison with L- amino acid tailed porphyrin and its zinc(II) complexes.

Amino Acids↗

PubMed2004

[Relationships between Aphis gossypii and its natural enemies in megranate field].

In this paper, the relevancy of Aphis gossypii with its natural enemies was studied by using grey systematic analysis. The results showed that the major natural enemies of Aphis gossypii were Tetragnathidae (0.8607), Therdion octomaculatum (0.8058), Therdion octomaculatum (0.7989), Haramonia aiyridis (0.7881) and Chrysopa sepetempunctata (0.7758). As for the daily total predation, the natural enemies which highly associated with the ideal dominant natural enemies were Erigonidium graminicola (0.8975), Tromobidiidae (0.8132), Propylacea japonica (0.7806) and Chrysopa sepetempunctata (0.7669); while for the quantity, Erigonidium graminicola (0.8482), Chrysopa sinica (0.7533), Tetragnathidae (0.7532), Therdion octomaculatum (0.7411) and Chrysopa sepetempunctata (0.7716) were the major natural enemies. According to the relational grade of the individuals between various natural enemies and ideal dominant natural enemies, the major natural enemies were Erigonidium graminicola (0.8461), Tromobidiidae (0.7325), Propylacea japonica (0.6983), Chrysopa sepetempunctata (0.6815) and Chrysopa sinica (0.6757). The species having >0.9567 horizontal and vertical niche overlaps with Aphis gossyppii were Erigonidium graminicola, Chrysopa sepetempunctata and Tetragnathidae, while the temporal niche overlaps between Erigonidium graminicola, Chrysopa sepetempunctata, tetragnathidae and Aphis gossyppii were >0.4020. It could be concluded that the main natural enemies of Aphis gossyppii were Erigonidium graminicola, Chrysopa sepetempunctata and Tetragnathidae.

Animals↗

PubMed2004

[A DRIFTS study of SO2 oxidation on the surface of CaCO3 particles].

CaCO3 is an important component of mineral dust aerosols in the atmosphere, but its role in atmospheric heterogeneous chemistry is still unclear. In this paper, the oxidation of SO2 on CaCO3 particles was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Formation of sulfite and sulfate was identified on the surface, and the role of O3 on the oxidation process is determined by comparing the experiments in different conditions. DRIFTS is proved as a useful tool for studying heterogeneous reactions on CaCO3 particles. The results show that in the presence of O3, SO2 can be oxidized into sulfate on the surface of CaCO3 particles. A two-step mechanism that involves adsorption of SO2 followed by oxidation is presented.

Calcium Carbonate↗