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Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 595 records · Page 33Linked to original sources
PubMed1995

[Studies on the histological classification of proliferative disease of breast and its relation with breast carcinoma].

According to the degree of fibroplastic proliferation, proliferative disease of breast can be divided into three types: lobular hyperplasia type, fibroadenosis type and fibrosclerosis type. Each type could have simple or compound lesions. The latter include: atypical hyperplasia of duct epithelial cells, large sweat gland metaplasia, cyst and fibroadenoma formation. The progress of lesions coincided with the increase of age. The age of fibrosclerosis patients were close to that of patients with breast carcinoma accompanied with proliferative breast disease. The level of PCNA expression in the three types of proliferative breast disease increased progressively and the level of PCNA expression in fibrosclerosis and breast carcinoma being similar. It is emphasized that in the fibrosclerosis type hyperplasia, the presence of twisting, fragmentation or incomplete encirclement of the periductal myoepithelial cells as well as the basement membrane of the tubules may be considered as a warning to call one's attention to follow up patients closely.

Adult↗
PubMed1995

Fluorescence spectroscopic study of the interaction of adenine and nucleotide with trichosanthin.

Trichosanthin (TCS) is an N-glycosidase that can attack the 28s rRNA of the ribosome at a highly conserved adenine residue. The interactions of adenine and its derivative nucleotides with TCS are reported. The fluorescence of Trp 192 of TCS is sensitive to the proximity of adenine, and produces a marked red shift indicative of trytophan in a more hydrophilic environment. By contrast AMP and ATP quench the maximal emission at 328nm. The binding of the adenine and ATP with TCS result in lower tryptophan accessibility to the quencher acrylamide, but higher tryptophan accessibility to the quencher iodide, while AMP caused higher tryptophan accessibility to acrylamide, and lower tryptophan accessibility to iodide. Also, the binding of nucleotides induces tryptophan heterogeneity in the protein. These findings lead us to propose that binding of nucleotides and adenine base cause different microenvironmental changes of the tryptophan residue, and Trp 192 may be involved in the active site of TCS.

Adenine↗
PubMed1995

[Clinical application of endoscopic injection of medication for stopping gastric bleeding].

The authors studied 40 patients with bleeding from peptic ulcer or gastric carcinoma, and evaluated the therapeutic effects of endoscopic injection of absolute alcohol and Bathroxobin. Among them, 20 patients were given absolute alcohol and the remaining 20 Bathroxobin (Reptilase). Absolute alcohol was injected submucosally at 4-6 pinpoints around the bleeding site (0.1-0.2ml/dose, total dose 0.5-1.2ml); Bathroxobin was injected similarly (1 kU/dose, total dose 0.5-1.0kU). Treatment failed in one patient receiving alcohol because of spouting artery bleeding and surgery was resorted to finally. The other 39 patients had successful stopping of the bleeding in one time. The effective rate is 97.5 percent (39/40) and the rate of re-bleeding is low. It is thus shown that endoscopic submucosal injection of absolute alcohol and Bathroxobin for stopping gastric bleeding is safe, simple and effective. However, more experience is needed in this respect.

Adult↗
PubMed1995

[Experimental studies of the effects of prestress on intact canine bone structure].

Three types of plate made of 316L medical stainless steel were applied in the experiment. They were divided into conventional plate, concave plate, sliding plate by their different shapes and functions. They were fixed on intact canine tibias and compared with intact canine tibias that were only fixed with conventional screws. Stress values were measured with static strain instrument in different conditions and in vitro tissue that was poured with disulphine blue. CT scanning was done in different stages. The experiment results proved that different extents of intraosseous prestress were reduced by different plate fixings. The conventional plate group with high stiffness produced the greater prestress and stress shielding value and slight circulation disorder in bone tissue in early stage, but the osteoporosity of tibias bone ocurred early (1 month); conventional plate with low stiffness produced the less prestress and stress shielding value and severe circulation disorder in bone in early stage, but the osteoporosity ocurred late (3 month). We consider the cause of local osteoporosity of tibias bone after plate fixed were mainly prestress, and stress shielding is secondary in early stage (3 month). The local circulation is disorder is not important factor.

Animals↗
PubMed1995

[Study on LDL receptors of liver non-parenchymal cells in hypertriglyceridemic rats induced by high carbohydrate diet].

In the present study, hypertriglyceridemia was induced by feeding S. D. rats with high carbohydrate diet (carbohydrate accounting for 80% of total calorie) for 5 days. Rat liver parenchymal cells (PC) and non-parenchymal cells (NPC) were prepared by collagenase method. Human plasma LDL, VLDL and HDL were isolated by density gradient ultracentrifugation method. 125I-LDL was labelled by ICI method. 125I-LDL binding to rat liver PC and NPC were measured by Goldstein and Brown's method. The results showed that both rat liver PC and NPC had LDL receptors to bind, uptake and degradate 125I labelled human plasma LDL. The Bmax of 125I-LDL binding to NPC was 7-fold higher than that of PC (P < 0.01), but the Kd values remained unchanged. The Bmax of 125I-LDL binding to liver NPC from hypertriglyceridemic rats was significantly higher than that of NPC from the normal diet (carbohydrate accounting for 60% of total calorie) rats (435.4 + 100.0 vs 307.1 +/- 76.8 ng/mg cell protein, n = 6, P > 0.05), but there was no difference in Kd between the HTG rats and normal rats (18.1 +/- 4.1 vs 17.2 +/- 4.0 micrograms/ml n = 6, P > 0.05). These results suggest that the increase in fractional catabolic rate of LDL in patients with hypertriglyceridemia reported by Vega and Grundy might be induced by the increase in number of LDL receptor on liver non-parenchymal cells.

Animals↗
PubMed1995

[Changes of collagen distribution in extrapulmonary arteries of hypoxia-induced pulmonary hypertensive rat].

Changes of collagen distribution in extrapulmonary arteries induced by hypoxia and the effects of ligustrazine (ligus) and 764-3 were investigated. Histological study showed that hypoxia could induce an increase of the medial and adventitial thickness of the pulmonary arterial trunk. An increase of type I and type III collagen fibers in pulmonary arterial trunk, particularly the increase of type III collagen fibers in adventitia of the pulmonary trunk were revealed by picrosirius-polarization methods. Ligus partially prevented the increase of type I and III collagen fibers of pulmonary arterial trunk. Electron microscopy showed that both the medial smooth muscle and adventitial fibroblasts were hypertrophic and hyperplastic, and the surrounding collagen fibers were increased.

Altitude Sickness↗
PubMed1995

[Mechanism of medical collagen for soft tissue augmentation].

This paper reports the fate of medical collagen after injected into rats. It is highly purified collagen. The persistence of it in rats is more than one year. It was found that fibroblasts and capillaries grew into the injections. Picrosirius-polarization demonstrated that the ration of type I and type III collagen changed. Fine green fibers of type III collagen were predominant at the early stage. Twelve months after implantation, most collagen fibers appeared as thick brilliant red fibers of type I collagen.

Animals↗
PubMed1995

[Analysis of beta-thalassemia mutations and prenated diagnosis in Chengdu population].

Ninety-five of non-differential diagnostic patients were detected by dot-blot analysis on enzymatically amplified DNA with a number of allele specific oligonucleotide probes complementary to the most common mutations in Chengdu population. Prenatal diagnosis was accomplished by the same procedure on enzymatically amplified amniocyte DNA. The result revealed fifty-eight cases of beta-thalassemia. Of the 73 chromosomes tested, twenty-eight (38.4%) had the codon 17(A-->T) mutation, twenty-one (28.8%) had the codon 41-42(-TTCT) mutation, fourteen (19.0%) had the IVS-I-654(C-->T) mutation; nt--28(A-->G) and nt--29(A-->G) mutations were six (8.2%) and four (5.5%) respectively.

Base Sequence↗
PubMed1995

[The establishment of ADBS data bank system for autopsy records].

The ADBS data bank system consists of PC 286 microcomputer, (or 386 and other more advanced machine) VGA color monitor, printer and ADBS V. 2.0 software. According to the international classification of diseases (ICD-9 or ICD-10, SNOMED), pathological diagnoses are coded and put into computer. This system has five functions: search, statistics, edition, print and system restore. For facilitating the operation of this system, all orders are listed as window menu. The statistic results can be shown as tables or figures and put out as disk files or prints. The system is currently an advanced computerized system of histopathological and autopsied records in Chinese.

Autopsy↗
PubMed1995

Preparation and characterization of monoclonal antibodies against aflatoxin B1.

Five hybridoma cell lines producing monoclonal antibodies (MAb) against Aflatoxin B1 (AFB1) were established after fusion of mouse myeloma cells (SP-2/O-Ag-14) with spleen cells isolated from male BALB/c mice immunized with AFB1-BSA conjugate. Among these, one MAb, designated AFB1-2H8, was of the subtype IgG3 and the acidic fluid of which gave high dilution titers (1:5 x 10(5). The sensitivity of a competitive inhibition enzyme immunoassay (CIEIA) using AFB1-2H8 for AFB1 demonstrated that the linear range was 0.5-50 ng/ml and the minimum detectable concentration of AFB1 was 0.01 ng/ml. The specificity of the MAb was determined and showed no significant crossreaction with any of the metabolites tested. So th-- MAb and the CIEIA described may be useful in the detection of AFB1 in food and feed.

Aflatoxin B1↗
PubMed1995

[Evaluation and its clinical significance of anti-platelet granule membrane protein-140 autoantibodies and anticalmodulin antibody in patients with severe pregnancy-induced hypertension].

OBJECTIVE: To study the effect of immune function of platelet on the pathogenesis of severe pregnancy-induced hypertension. METHODS: 46 plasma samples from patients with severe pregnancy-induced hypertension (PIH) were evaluated for autoantibodies directed against granule membrane protein-140 (GMP-140) and anticalmodulin antibody (A-CaM) using ELISA methods. RESULTS: Autoantibodies to GMP-140 existed in 13 patients with severe PIH (28.6%), after SDS-page of purified GMP-140 immunoblotting showed that 1 out of 8 sera from patients presented a staining band with M.W. of 140 kd. 29 plasma samples were found autoantibodies to GMP-140, GP IIb/IIIa and GP Ib/IX, simultaneously. It was shown that antiGMP-140 activities coexisted with anti-GP IIb/IIIa and/or anti-GPIb/Ix in 29 cases (81.8%). The elevated A-CaM was observed in the patients with severe PIH reaching to 20.02 +/- 3.74U/L, that was much higher than those from the normal (7.53 +/- 2.57U/L, P < 0.05). CONCLUSION: Our study provided the evidence for autoantibodies to GMP-140 and A-CaM in some of patients with severe PIH, it has certain importance for further study on the pathogenesis of severe PIH.

Autoantibodies↗
PubMed1995

[Effects of electroacupuncture on gastrin, mast cell and gastric mucosal barrier in the course of protecting rat stress peptic ulcer].

The experimental Wistar rats were divided into two groups, the acupuncture group and the control group. Stress-induced gastric ulcer models were established by immersion of restrained rats in water. The electroacupuncture was able to protect stress rat from stress induced peptic ulcer. The results indicated that electroacupuncture protecting rat from stress ulceration was relevant to enhancing gastric mucosal barrier, stabilizing gastric mast cell and inhibiting the gastrin levels in gastric mucous.

Animals↗
PubMed1995

[Influence of acupuncture on blood pressure, contents of NE, DA and 5-HT of SHR and the interrelation between blood pressure and whole blood viscosity].

Twenty spontaneous hypertensive rats (SHR) with systolic blood pressure (SBP) >or= 20 kPa were chosen and divided randomly into two groups (acupuncture group and control group). The former was acupunctured on bilateral Quchi (L1 11), Zusanli (ST 36). Another 46 immature SHRs which were about 7-week-old with SBP ranged from 16 kPa to 20 kPa were given 10% high molecular weight dextran (HMWD) or normal saline by intervention respectively. The results showed: 1. After three course of acupuncture, SHRs' SBP dropped remarkably from 25.493 +/- 0.73 kPa to 19.547 +/- 0.555 kPa (P < 0.01); 2. After three courses of acupuncture, NE and 5-HT contents in plasma were lowered (P < 0.05, < 0.01) and DA content in plasma was increased (P < 0.05) compared with that in the control group. 3. After three course of acupuncture, NE content in brainstem, hypothalamus, cerebral cortex increased (P < 0.005-0.01) and DA content in brainstem, cerebral cortex increased remarkably (P < 0.005-0.01) compared with that in the control group. 5-HT content in brainstem, hypothalamus, and cerebral cortex increased obviously compared with that in the control group. 4. After 1 or 2 hours of intervention of 10% HMWD to immature SHR, the whole blood viscosity and blood pressure rise remarkably compared with normal saline group. The experiment implies that the mechanism of lowering the blood pressure of SHR by acupuncture lies in that it can adjust NE, DA and 5-HT contents in plasma and central nervous system to adjust the activity of sympathetic, reduce whole blood viscosity etc.

Animals↗
PubMed1995

[Regulation of purine biosynthetic genes expression in Salmonella typhimurium. III. Isolation of O+ and Oc fragments of pur JHD].

It has been known that 10 enzymatic reactions are involved in de novo biosynthesis of IMP in Salmonella typhimurium. 10 genes encoding the enzymes have been localized on the Salmonella typhimurium chromosome. Seven structure genes including pur JHD operon are negatively regulated by purR. In this study the purJHD operon containing O+ and Oc were cloned in vivo respectively. Two preliminary clones, p2-9 (O+) and pC-12 (Oc) were identified to be the hybrid plasmids carrying intact pur JHD operon by genetic complementary test and reconstruction enzyme analysis. The fragments of O+ and Oc were subcloned on to pUC19 and DNA sequence were determined directly by DNA sequencer. The DNA sequence of O+ fragment revealed that a 16 base consensus sequence (named PUR box) GCGCAAACGTTTTCGT also existed in control region of pur JHD operon in Salmonella typhimurium. The DNA sequence of Oc fragment indicated that only one base change occurred at the 14th position of PUR box(C-->T). Our result strongly support the idea that PUR box is binding region of purR protein.

Base Sequence↗
PubMed1994

A transcribing RNA polymerase molecule survives DNA replication without aborting its growing RNA chain.

We have demonstrated elsewhere that a precisely placed, stalled Escherichia coli RNA polymerase ternary transcription complex (polymerase-RNA-DNA) stays on the DNA template after passage of a DNA replication fork. Moreover, the bypassed complex remains competent to resume elongation of its bound RNA chain. But the simplicity of our experimental system left several important questions unresolved: in particular, might the observation be relevant only to the particular ternary complex that we studied, and can the finding be generalized to a transcribing instead of a stalled RNA polymerase? To address these issues, we have created three additional ternary transcription complexes and examined their fates after passage of a replication fork. In addition, we have examined the fate of moving RNA polymerase molecules during DNA replication. The results suggest that our previous finding applies to all transcription intermediates of the E. coli RNA polymerase.

Adenosine Triphosphate↗
PubMed1994

Volatile N-nitrosamines and their precursors in Chinese salted fish--a possible etological factor for NPC in china.

Epidemiological studies show that the consumption of Chinese salted fish is a causative factor for nasopharyngeal carcinoma (NPC) in southern China. In the present study, N-nitrosamines and their precursors were analyzed in 145 samples of cooked, salted fish collected from various areas in China. The results show that N-dimethylnitrosamine (NDMA), N-diethylnitrosamine (NDEA), N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP) were present in the salted fish. Total volatile N-nitrosamines (TVN) in the salted fish were 0.028 to 4.54 mg/kg. The samples from areas with higher NPC risk showed a higher average level of TVN than those from areas of lower NPC risk. Positive correlations were found between the levels of NDMA, NDEA and TVN and mortality from NPC. Although neither the nitrates nor the nitrites in the salted fish were present at significantly high levels, in vitro data regarding nitrosation of salted fish showed that the N-nitrosamine content had increased substantially. The results support the conclusion that the high NPC risk in southern Chinese may be attributed to consumption of salted fish containing high levels of N-nitrosamines.

Animals↗
PubMed1994

Mutations of two PMS homologues in hereditary nonpolyposis colon cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC) is one of man's commonest hereditary diseases. Several studies have implicated a defect in DNA mismatch repair in the pathogenesis of this disease. In particular, hMSH2 and hMLH1 homologues of the bacterial DNA mismatch repair genes mutS and mutL, respectively, were shown to be mutated in a subset of HNPCC cases. Here we report the nucleotide sequence, chromosome localization and mutational analysis of hPMS1 and hPMS2, two additional homologues of the prokaryotic mutL gene. Both hPMS1 and hPMS2 were found to be mutated in the germline of HNPCC patients. This doubles the number of genes implicated in HNPCC and may help explain the relatively high incidence of this disease.

Adenosine Triphosphatases↗