Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 343 records · Page 19Linked to original sources

PubMed1999

The caudal-related homeodomain protein Cdx-2 regulates vitamin D receptor gene expression in the small intestine.

The actions of 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) are mediated through the nuclear vitamin D receptor (VDR). The regulation of VDR abundance plays an important role in determining the magnitude of the target cell response to 1,25(OH)2D3. The major physiological activity of 1,25(OH)2D3 is the regulation of calcium absorption in the small intestine, and the level of VDR is an important factor in this regulation. However, the characterization of VDR gene expression in the small intestine remains unknown. In the present study, we investigated the regulation of the human VDR (hVDR) gene expression in the small intestine. The 4.0 kb of the 5'-flanking region of the hVDR gene promoter was cloned and characterized by the measurement of luciferase activity and an electrophoretic mobility-shift assay (EMSA). With the EMSA, we found that Cdx-2 (a homeodomain protein-related caudal) binds to the sequence 5'-ATAAAAACTTAT-3' at -3731 to -3720 bp (hVD-SIF1) relative to the transcription start site of the hVDR promoter. This sequence is very similar to the human sucrase-isomaltase footprint 1 (SIF1) element. With a competition analysis and specific antibodies for Cdx-2, we demonstrated that Cdx-2 is able to activate VDR gene transcription by binding to this element. The mutation of the hVD-SIF1 sequence in the hVDR gene promoter markedly suppressed the transactivation of the reporter gene in Caco-2 cells. In addition, the DNA fragment (-3996 to -3286) containing the hVD-SIF1 binding site increased transcription when placed upstream of the herpes simplex virus thymidine kinase promoter. These findings suggest that Cdx-2 plays an important role in the intestine-specific transcription of the hVDR gene.

Animals↗

PubMed1999

Generation of stable recombinant retroviruses containing the beta-globin genes linked to complex regulatory elements by using transient transfection.

A transient packaging method for a retroviral vector containing beta-globin sequences, mediated by Ca3(PO4)2 precipitation, generated stable recombinant beta-globin retroviruses with intact viral genomes. We suggest the use of this method as an alternative means to overcome the production of beta-globin encoding retroviruses with aberrant viral genomes using the routine packaging procedure.

Genetic Vectors↗

PubMed1999

Marrow cytokine transcripts and the secondary hematologic disorders.

A comparison was made of the cytokine transcripts in normal, monoclonal, MDS, and AML marrow aspirates. While both normal and monoclonal marrow aspirates contain transcripts for SCF, few MDS or AML marrow aspirates contain these transcripts. Similarly, IL1ra transcripts are found with reduced frequency in MDS and AML marrow aspirates. The fall in SCF transcripts between monoclonal and MDS marrow aspirates parallels the appearance of apoptosis and the reduced in vitro proliferative ability which are characteristics of MDS marrow aspirate cells. The frequent IL1beta production by MDS and AML marrow aspirate cells, with few marrow aspirates producing IL1ra transcripts, suggests that unbalanced IL1beta effects may contribute to the proliferative advantage of MDS and AML cells over their normal counterparts.

Bone Marrow↗

PubMed1999

Retinal ischemic preconditioning in the rat: requirement for adenosine and repetitive induction.

PURPOSE: A brief period of ischemia can induce a remarkably complete state of ischemic tolerance in the retina, a phenomenon known as ischemic preconditioning (IPC). The mechanisms of IPC were studied in the rat retina by examining the role of adenosine as a possible mediator and determining whether IPC protection could be induced more than once in the same rat. METHODS: Retinal ischemia was produced for 60 minutes in ketamine-xylazine-anesthetized Sprague-Dawley rats, and recovery was measured using electroretinography. Twenty-four hours earlier, the IPC stimulus of 5 minutes of ischemia was applied. To test the role of adenosine as a mediator of IPC, the selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.45 mg/kg, 2.25 mg/kg, or 4.5 mg/kg), the A2a antagonist 8-(3-chlorostyryl)caffeine (CSC; 0.1 mg/kg or 1.0 mg/kg), or their cyclodextrin vehicle were administered 15 minutes before IPC. To examine whether exogenous adenosine administration could mimic IPC, animals received intravitreal injections of the adenosine A1 receptor stimulant adenosine amine congener (ADAC) or the A2a stimulant CGS21680, followed by ischemia 24 hours later. To test the hypothesis that IPC could be induced repeatedly without loss of protection, rats were divided to receive IPC or sham IPC, followed 10 days later by IPC or a sham procedure, and 24 hours later by 60 minutes of ischemia. RESULTS: Adenosine A1 receptor blockade with 4.5 mg/kg DPCPX administered intraperitoneally (IP) before or immediately after 5 minutes of ischemia completely blocked IPC protection, whereas lower doses resulted in partial blockade. CSC at the lowest dose (0.1 mg/kg) had no significant effect on IPC's protective effect, whereas partial blockade was found with 1.0 mg/kg CSC. A1 or A2a receptor stimulation produced partial but significant mimicking of IPC protection, effects that were antagonized by DPCPX or CSC. Ischemic preconditioning applied twice, separated by 10 days, and followed by 60 minutes of ischemia 24 hours after the second IPC stimulus, resulted in nearly identical recovery of function after ischemia compared with IPC performed one time. CONCLUSIONS: Adenosine, acting through the A1 and A2a receptors, is a critical component in the induction of ischemic tolerance after preconditioning in the retina. The neuroprotective effects of IPC in the retina are lost over time but may be reinduced by subsequent application of the IPC stimulus.

Adenosine↗

PubMed1999

Regulation of hepatitis B virus expression in progenitor and differentiated cell types: evidence for negative transcriptional control in nonpermissive cells.

Mechanisms regulating cell type-specific gene expression are not completely understood. We utilized hepatitis B virus (HBV) enhancer I and preS1 promoter sequences, which exhibit cell type specificity, to analyze transcriptional control in pluripotential murine embryonic stem (ES) cells, bipotential HBC-3 progenitor liver cells, mature hepatocytes, and fibroblasts. In transient transfection assays, HBV sequences were most active in primary hepatocytes, followed by HBC-3 and ES cells, and became inactive in fibroblasts. Cotransfections with HNF-3 or C/EBP plasmids increased expression of HBV sequences in hepatocytes and HBC-3 cells. However, increased HBV expression was not observed in ES cells and HBV remained inactive in fibroblasts, suggesting different transcriptional controls, which was compatible with alterations in the abundance of endogenous transcription factors. Analysis in somatic hybrid cells created from NIH 3T3 fibroblasts and Hepa1-6 mouse hepatocytes with expression of albumin and selected hepatic transcription factors showed that HBV sequences were expressed weakly but without increased expression following transfection of HNF-1, HNF-3, and C/EBP plasmids. These findings indicated that repression of HBV in nonpermissive cells involved inactivation of transcription factor activity. Expression of HBV in stem cells is relevant for mechanisms concerning viral persistence and oncogenesis, as well as analysis of hepatocytic differentiation in progenitor cells.

3T3 Cells↗

PubMed1999

[The effect of serum TGFb1 of patients with chronic hepatitis B in liver fibrosis formation].

OBJECTIVES: To observe the relation between serum transforming growth factor beta 1(TGF beta 1) and level of PCIII, LN, HA, proliferation of hepatic fibrotic tissue. METHODS: Serum TGF beta 1 was detected by ELISA in 58 patients with chronic hepatitis B(CHB) and 18 patients with liver cirrhosis(LC). 20 healthy persons served as normal control(NC). Liver puncture was performed in 29 patients with CHB. Diagnosis of pathological histology and quantitative analysis of collagenous and reticular fibers were made. RESULTS: (1)Serum TGF beta 1 levels in CHB and LC were notably higher than in NC (P < 0.01) and increased successively in mild, moderate and severe degrees of CHB and LC(P < 0.01/0.05). (2)Serum TGF beta 1 was correlated with serum levels of PCIII, LN, HA(P < 0.01/0.05)positively. The quantity of hepatic collagenous and reticular fibers went up in mild, moderate and severe degrees of CHB(P < 0.01/0.05). Meanwhile serum TGF beta 1 rose at the same degree. CONCLUSION: Serum TGF beta 1 levels increase in CHB and LC. With hepatic pathological change worsening, serum TGF beta 1 and the quantity of hepatic collagenous and reticular fibers increased to the same degree. This suggests that TGF beta 1 is a crucial factor in accelerating liver fibrosis and plays a decisive role in liver fibrosis.

Adult↗

PubMed1999

[Chromosomal location of the genes conferring the tolerance to phosphorus deficiency stress in Lophopyrum elongatum genome] [In Process Citation]

Identification and genetic analysis were conducted on the tolerance to phosphorus deficiency stress by using a set of alien disomic addition lines (DA lines) and disomic substitution lines (DS lines) of common wheat Chinese Spring-Lophopyrum elongatum (2n = 2x = 14, EE), a closely related wheat species. The results indicated that chromosomes 4E and 6E in L. elongatum may carry the genes conferring the tolerance to phosphorus deficiency stress with much stronger effect over the background parent Chinese Spring. DA lines derived from chromosomes 2E and 3E behaved quite different from the corresponding DS lines. Although DA2E and DA3E were susceptible to phosphorus deficiency, the DS lines performed much better than Chinese Spring, DA2E and DA3E under both control and the deficiency conditions. However, the strongly repressed stress tolerance was located on chromosome 5E. In addition, the possible reasons for the different reponses to phosphorus deficiency between DA and DS lines of chromosomes 2E and 3E are discussed.

Journal Article↗

PubMed1999

[The diagnostic value of computed tomography and ultrasonography for detecting hypoxic-ischemic encephalopathy].

OBJECTIVE: To investigate diagnostic value of computed tomography (CT) and ultrasonography for detecting hypoxic-ischemic encephalopathy (HIE) and to evaluate their clinical implications. METHODS: 94 neonates were examined with CT and ultrasonography, respectively, for detecting HIE and the results were compared to clinical investigation. RESULTS: Significant difference (P < 0.01) was found for diagnosis of mild and moderate HIE by CT and ultrasonography. Compared with clinical diagnosis, the agreement rates of ultrasonography and CT were 83% and 39% (P < 0.01) for mild HIE, and 100% and 43% (P < 0.01) for moderate HIE respectively. There was no difference for detecting severe HIE among clinical diagnosis, CT and ultrasonography. Additionally, 9 cases with intracranial hemorrhage were detected by CT in which only 3 cases were found by ultrasonography. CONCLUSIONS: Compared with clinical finding for diagnosis of mild and moderate HIE, the agreement rate of ultrasonography is higher than that of CT. However, CT is more sensitive to detect intracranial hemorrhage than ultrasonography.

Female↗

PubMed1999

Changing pattern of heart diseases in Shanghai from the 1950s to 1980s.

OBJECTIVE: To determine the pattern of dynamic change in types of heart diseases in the past 4 decades for providing a reference to treatment and prevention of heart diseases in China. METHODS: All adult cardiac patients admitted to the Zhong Shan Hospital and Hua Shan Hospital from 1948 to 1989 were analyzed. The constituent ratio of different heart diseases in the 1950s, 1960s, 1970s and 1980s was compared. RESULTS: The percentage of heart diseases among medical inpatients increased in each of the recent 4 decades, from 9.89%, 15.69%, 20.90% to 23.54% respectively. The constituent ratio of different heart diseases changed, coronary heart disease constituted the highest proportion, next came rheumatic heart disease, and congenital heart disease was in third place. Congenital heart disease, myocarditis, cardiac dysrhythmia without organic heart disease, cardiomyopathy and endocarditis increased, rheumatic heart disease, pulmonary heart disease and hypertensive heart disease apparently decreased; syphilitic heart disease could rarely be encountered. CONCLUSION: China is now facing a low overall death rate, a long life expectancy and an aging population. The incidence of heart diseases increased gradually and patterns of heart diseases kept changing. The overall trend is that heart diseases which were not related to infection are increasing while heart diseases related to bacterial infection are decreasing.

Arrhythmias, Cardiac↗

PubMed1999

[The association between signal-regulatory protein alpha and hepatocellular carcinoma].

OBJECTIVE: To study the roles of signal-regulatory protein alpha (SIRP alpha) in the development of hepatocellular carcinoma (HCC). METHODS: 42 pairs of HCC and the surrounding noncancerous hepatic tissues were used. The expression of SIRP alpha in various tissues was determined by Northern blot analysis and immunohistochemistry assay, by which together with the pathologic characteristics of each sample, the role of SIRP alpha was investigated. RESULTS: The expression of SIRP alpha significantly decreased in 21 cases of samples (50.0%) to the 3.9 kb transcript and 27 cases of samples (64.3%) to the 2.5 kb transcript respectively. The SIRP alpha decreasing rate in large HCC(> 5 cm in diameter) was higher than in small HCC (< or = 5 cm in diameter), and in HCC with cancer embolus was higher than that of without cancer embolus. No association was found between the SIRP alpha expression and the patient's age, tumor grade, tumor capsule, serum AFP level, and HBV infection. Immunohistochemistry showed that all the normal hepatocytes, cholangioepithelial cells, Ito cells, regenerated hepatocytes, new generated cholangioepithelial cells and part of HCC cells were positive. The HCC tissues in which SIRP alpha was down-regulated showed positive particles becoming weaker and less, and some tumor cells and area were completely negative. CONCLUSION: The expression of SIRP alpha especially 2.5 kb transcript is down-regulated in HCC, which is closely related with the tumor growth and invasiveness. SIRP alpha may be an important negative regulator of HCC.

Antigens, Differentiation↗

PubMed1999

[Effects of raf-1 gene overexpression on proliferative phenotype of rat mesangial cells].

OBJECTIVE: To investigate the regulating effects of raf-1 gene overexpression on phenotypic characteristics related proliferation in rat mesangial cells (MC). METHODS: Raf-1 gene was stably transfected and overexpressed in rat MC. Growth rate, cell cycle and activity of mitogen-activated protein kinases including ERK and JNK were compared between transfected and normal cells by cell counting, FACS and specific substrate phosphorylation. RESULTS: The growth rate of raf-1 transfected cells was normal from the 1st to 3rd days, but slower on the 5th day. At the 7th day, the cell number in raf-1-transfected clones was much less than in controls (22.0 +/- 2.5) x 10(5) vs (33.4 +/- 2.7) x 10(5), (P < 0.05). Most of raf-1 transfected cells stayed in the G0/G1 stage in cell cycle (81.3 +/- 3.7)% vs (62.3 +/- 2.4)%, (P < 0.01); the percentage of cells in S stage was decreased markedly (8.3 +/- 0.9)% vs (27.0 +/- 1.5)%, (P < 0.01). ERK activity was elevated (214 +/- 16) pmol.mg-1.min-1 vs (82 +/- 9) pmol.mg-1.min-1, (P < 0.05), but JNK activity was inhibited by about 50% in raf-1 overexpressed cells compared to controls. CONCLUSION: Raf-1 is a critical intracellular signal for regulating proliferative phenotype in rat MC. Its constitutive overexpression leads these cells to be silent indicating arrest cell cycle, which may be mediated by regulating protein in cell cycle and intracellular JNK activation.

Animals↗

PubMed1999

[Evaluation of biliary CEA in the diagnosis of colorectal cancer with liver metastases].

OBJECTIVE: To evaluate the clinical significance of biliary CEA for diagnosing colorectal cancer with liver metastases. METHODS: Three groups of patients were examined: 30 patients with benign disease in group A, 30 patients with colorectal cancer in group B, and 15 colorectal cancer patients with liver metastasis in group C. Fasting venous blood was drawn, and in the meatime, bile was collected by duodenal tube drainage before operation. CEA was detected with immunosorbent assay kit supplied by Boehringer. RESULTS: The serum level of CEA in group A, B, and C was (3.2 +/- 0.5) ng/ml, (11.7 +/- 2.4) ng/ml, and (14.8 +/- 3.5) ng/ml, respectively. The biliary CEA level was (23.7 +/- 8.6) ng/ml, (129.4 +/- 36) ng/ml, and (862 +/- 227) ng/ml, respectively. The difference in biliary CEA between group B and group C was statistically significant (P < 0.01). CONCLUSION: CEA level in the bile collected by duodenal drainage helps confirm liver metastasis in patients with colorectal cancer.

Adult↗

PubMed1999

[The roles of oxygen free radicals and superoxide dismutase in the inflammatory injury in animal oral mucosa].

OBJECTIVE: To study the roles of oxygen free radicals (OFRs) and superoxide dismutase (SOD) in the inflammatory injury in animal oral mucosa. METHODS: 1. The animal model was established in which an acute oral mucosal inflammation was induced by OFRs. Enzyme histological methods and biochemical methods were used respectively to investigate the activities of some important enzymes such as nicotinamide adenine dinucleotide phosphate-diaphorase and the amount of aminohexoses in the lesions; 2. Electron spin resonance and radioimmunoassay were ultilize respectively to study the effects of exogenous SOD on the amount of OFRs and prostaglandin E2(PGE2) in the lesions. RESULTS: 1. The activities of the enzymes in the oral lesions decreased and the amount of aminohexoses increased significantly; 2. Local administrating SOD could reduce the amount of OFRs and PGE2 in the lesions sufficiently. CONCLUSION: OFRs induced the inflammatory lesion by injuring some important enzymes and connective tissues in the oral mucosa. Local administrating SOD could scavenge OFRs and PGE2 in the oral mucosa sufficiently and reduce the degree of OFRs--induced oral mucosal inflammatory injury.

Animals↗

PubMed1999

[The abnormal expression of pRb during DMBA-induced hamster buccal pouch carcinogenesis].

OBJECTIVE: To study the expression and role of pRb in 7,12-dimethylbenzanthracene(DMBA) induced hamster buccal pouch carcinogenesis. METHODS: DMBA (0.5%) in acetone was applied to the right buccal pouch 3 times per week for up to 12 week. Paraffin-embedded sections were used for pRb immunohistochemical determination (ISAB technipue, polyclonal antibody c-15 for pRb). The density of staining was analysed by rank sum test. RESULTS: The positive staining of pRb was strong in normal buccal epithelium, no alteration of pRb staining in 3 week (hyperplastic epithelium) and somewhat reduced between 6 and 9 week (dysplastic lesion), but it was marked reduced in 12 week (carcinoma). Statistical analysis found that changes of pRb were associated with stages of carcinogenesis. CONCLUSION: These results indicate that abnomal expression of Rb gene product could be related to oral carcinogenesis and may serve as a biomarker for supervising oral malignancy.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

[The effect of aminoguanidine, a nitric oxide synthase inhibitor, on bleomycin-induced lung injury in rats].

OBJECTIVE: To observe the dynamic change of the nitric oxide synthase (NOS) activity of the lung in bleomycin -induced pulmonary fibrosis in rats and to investigate the effect of aminoguanidine (AG), a selective inhibitor of inducible NOS on this animal model. METHODS: Sixty SD rats were divided into three groups in random: control group, untreated model group, AG-treated group. On experimental day (day 0), the rats were intratracheally instilled with bleomycin (5 mg/kg body weight) or sterile saline, and then treated with AG (50 mg x kg(-1)) x d(-1)), intraperitoneally) or saline until they were killed. On days 3, 7, 14, 28 after instillation, five rats of each group were sacrificed and the lungs were harvested for histopathological examination and determination of NOS activity, MDA and TNF. RESULTS: NOS activity in the lung homogenate was elevated quickly after bleomycin instillation and peaked on day 7, then declined. Treatment of AG remarkably ameliorated the alveolitis caused by bleomycin. The subsequently pulmonary fibrosis was also decreased, but there was no statistically significance. AG did not affect the increased level of MDA and TNF-alpha caused by intratracheally instilled bleomycin. CONCLUSIONS: Nitric oxide seems to play an important role in the development of pulmonary fibrosis, especially in the alveolitis phase.

Animals↗

PubMed1999

[Can esophagogastric anastomosis prevent gastroesophageal reflux].

OBJECTIVE: To investigate the possible anti-reflux function of esophagogastric anastomosis in the patients after receiving resection of cardiac cancer. METHODS: One hundred and ninety-two patients were studied by video-assisted gastroscopy, manometry, 24-h pH esophageal monitoring, radioscintigraphy and scanning electron microscopy. RESULTS: Abnormalities were found in 90.2% of patients through endoscopy. Resting pressure in esophageal body was higher than that in normal controls, and in the stomach, lower. Twenty-four hour pH monitoring demonstrated that gastroesophageal reflux (GER) did not occur when the patients slept in semi-reclining position, and occurred in all patients when slept in supine position. Scintigraphic study showed that 2/3 of the patients had reflux, occurrence of which was not affected by the length of postoperative period. Scanning electron microscopic examination showed that degeneration, exfoliation of esophageal mucosal epithelial cell, and derangement of micro-fold and inflammatory oedema of cytomembrane may be directly caused by reflux. CONCLUSIONS: GER exists in the majority of the patients after esophagogastrectomy and esophagogastrostomy for cardiac cancer. The occurrence of GER is not affected by the length of postoperative period. Some detecting methods fail to show the existence of GER, and 24-h pH monitoring is the most reliable method for detecting GER. Sleep in semireclining position is an effective method of preventing GER in postoperative patients.

Adult↗

PubMed1999

[Expression and significance of MXR7 mRNA in human hepatocellular carcinoma].

OBJECTIVE: To find out the expression and significance of MXR7 mRNA in human hepatocellular carcinoma. METHODS: The (32)P labeled and purified PCR product of MXR7 cDNA was taken as probe. MXR7 mRNA expression was detected by Northern blot analysis in 30 samples of preoperatively untreated HCC and corresponding surrounding non-cancerous hepatic tissue, and 12 normal liver tissues confirmed pathologically. RESULTS: The frequency of MXR7 mRNA expression in HCC, the corresponding surrounding noncancerous hepatic, and normal liver tissues was 76.6%, 13.3% and 0, respectively. The frequency of MXR7 mRNA expression in HCC without serum AFP elevation and in HCC < 5 cm was 9/10 and 5/6 respectively. CONCLUSIONS: MXR7 mRNA over-expression in human HCC is common and MXR7 mRNA may be expressed at early stage of HCC and can serve as tumor biomarker for HCC. The detection of MXR7 mRNA expression in liver puncture tissues may find small HCC without serum AFP elevation in the subclinical stage.

Adult↗

PubMed1999

[Transcatheter arterial embolization of renal carcinoma with absolute ethanol].

OBJECTIVE: To study transcatheter arterial embolization (TAE) of renal carcinoma using absolute ethanol so as to reduce bleeding for a higher resection rate, as a palliative treatment for advanced renal carcinoma. METHODS: Using Seldinger method, we treated 25 cases of renal carcinoma with transcatheter arterial embolization. RESULTS: The average bleeding of 25 cases during nephrectomy was 210ml after TAE. There was no mortality and serious complication. But there was pain and fever in most cases. CONCLUSIONS: TAE with absolute ethanol is an effective, safe and easy procedure. It could be used as an adjuvant therapy for renal carcinoma.

Adult↗