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Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 577 records · Page 32Linked to original sources
PubMed1996

Necrotic and apoptotic myocyte cell death in the aging heart of Fischer 344 rats.

To determine the effects of aging on myocyte cell death, Fischer 344 rats at 3, 7, 12, 16, and 24 mo of age were injected with myosin monoclonal antibody for the localization and quantification of necrotic myocyte cell death in the left ventricle, interventricular septum, and right ventricle. Conversely, the presence of DNA strand breaks in myocyte nuclei, indicative of programmed cell death, was evaluated by the terminal deoxynucleotidyl transferase assay and confirmed by DNA laddering. Myocyte necrosis, which involved nearly 1,000 myocytes in the left ventricular free wall at 3 mo, progressively increased with aging, reaching a value of 13,600 myocytes at 24 mo. Corre- sponding values in the interventricular septum were 300 and 9,400 myocytes. In the right ventricle, there were 270 necrotic myocytes at 3 mo and 9,000 at 24 mo. Programmed myocyte cell death was restricted to the left ventricular free wall and included 140 cells at 3 mo. This form of myocyte cell death increased at the subsequent age intervals, resulting in the involvement of 874 cells at 24 mo. The combination of necrosis and apoptosis in the left ventricular free wall was associated with 1,150 cells dying at 3 mo and 14,500 at 24 mo. In conclusion, myocyte cell death, apoptotic and necrotic in nature, constitutes an important determinant of the aging process, possibly mediating the occurrence of ventricular dysfunction and failure in the old heart.

Aging↗
PubMed1996

Regulation of PDGF-beta receptor-operated Ca2+ channels by phospholipase C-gamma 1 in glomerular mesangial cells.

Platelet-derived growth factor (PDGF)-induced Ca2+ signaling mechanisms were examined in cultured rat glomerular mesangial cells. PDGF-BB stimulated the tyrosine phosphorylation of phospholipase C (PLC)-gamma 1, the formation of a PLC-gamma 1/PDGF-beta receptor membrane complex, and the generation of intracellular inositol 1,4,5-trisphosphate (IP3). Preincubation with a tyrosine kinase inhibitor (genistein) abolished these PDGF-induced responses. Activation of 1-pS Ca2+ channels in cell-attached patches by intrapipette PDGF-BB was also abolished by tyrosine kinase inhibition. In the absence of PDGF-BB, channels were activated in cell-attached patches exposed to intrapipette thapsigargin (IP3-independent releaser of intracellular Ca2+ stores) and in excised inside-out patches exposed to increasing "cytoplasmic" Ca2+ (10(-8) to 10(-6) M). In cell-attached patches, channel activation by PDGF-BB was abolished when extracellular Ca2+ was < 1 mM. In glomerular mesangial cells 1) PDGF-BB stimulates tyrosine phosphorylation of PLC-gamma 1, PDGF-beta receptor/PLC-gamma 1 membrane complex formation, IP3 production, and 1-pS Ca2+ channel activity; 2) all four PDGF-induced responses are abolished by tyrosine kinase inhibition; 3) PDGF receptor-operated Ca2+ channels are sensitive to both intra- and extracellular Ca2+.

Animals↗
PubMed1996

Type frequency and antimicrobial susceptibility of Mycobacterium avium-intracellulare complex strains isolated in Italy from AIDS and non-AIDS patients.

Typing of the glycopeptidolipid antigens performed by thin layer chromatography on 59 Mycobacterium avium-intracellulare (MAC) strains isolated in Italy from AIDS patients showed that the most frequent types were 1, 4, 3, 8, and 21 (24, 19, 14, 14 and 8% of the strains, respectively). Among non-AIDS patients, types 1, 4 and 8 were also frequently found. The antimicrobial susceptibility tested in agar and/or liquid media to a panel of drugs indicated in clofazimine and rifabutin effective agents against both AIDS and non-AIDS strains. The data obtained show that MAC type distribution in Italy appears to be different from that reported for other countries. No major differences in drug susceptibility between AIDS and non-AIDS related strains were found.

AIDS-Related Opportunistic Infections↗
PubMed1996

Inhibitory effect of CV4151, a thromboxane A2 synthetase inhibitor, on ventricular arrhythmias induced by coronary artery occlusion in rats.

The purpose of this study was to determine whether thromboxane A2 (TXA2) is involved in the development of ventricular arrhythmias produced by coronary artery occlusion. Ventricular arrhythmias were induced by coronary artery occlusion in 66 male Sprague-Dawley rats. Rats were separated into 4 groups, and saline (n = 19) or CV4151 (a TXA2 synthetase inhibitor)(10 mg/kg, n = 14; 30 mg/kg, n = 15; or 100 mg/kg, n = 18) was injected intravenously 5 min before coronary artery occlusion. The antiarrhythmic effect of CV4151 was assessed in terms of the number of ventricular premature complexes (VPCs), the combined duration of ventricular tachycardia (VT) and ventricular fibrillation (Vf), the incidence of Vf, and the mortality rate within 30 min after occlusion. The total number of VPCs was as follows; control: 1789 +/- 330 beats: 10 mg/kg group: 1289 +/- 302 beats: 30 mg/kg group: 1008 +/- 229 beats: 100 mg/kg group: 986 +/- 275 beats, with no significant differences between groups. The incidence of Vf was significantly reduced in the 30 mg/kg and 100 mg/kg groups, as was the combined duration of VT and Vf and the mortality rate. Our results indicate that the TXA2 synthetase inhibitor CV4151 reduces the incidence of lethal arrhythmias induced by coronary artery occlusion in rats.

Animals↗
PubMed1996

Pituitary adenylate cyclase-activating peptide stimulates cyclic AMP accumulation in UMR 106 osteoblast-like cells.

Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) share 68% homology and function as neurotransmitters or neuroendocrine factors. Although VIP immunoreactivity has been detected in bone cells, the presence of PACAP or PACAP receptors in bone has not been determined. In this study, we investigated the role of PACAP and VIP in regulating cAMP accumulation in the UMR 106 osteoblast-like tumor cell line. PACAP 27 (10(-9) to 3 x 10(-7) M), PACAP 38 (10(-9) to 3 x 10(-7) M) and VIP (10(-8) to 10(-6) M) stimulated cAMP accumulation up to eightfold. PACAP 27 was slightly more potent than PACAP 38, and both were tenfold more potent than VIP. Both PACAP- and VIP-stimulated cAMP accumulation were potentiated by 4 beta-phorbol 12-myristate 13-acetate, an activator of protein kinase C. Two PACAP antagonists, PACAP 6-27 (3 x 10(-6) M) and PACAP 6-38 (3 x 10(-6) M), blocked PACAP- and VIP-stimulated cAMP accumulation. Two VIP antagonists ([Lys1,Pro2,5,Arg3,4,Tyr6]-VIP, and [4 Cl-D-Phe6,Leu17]-VIP) did not reduce the PACAP- or VIP-stimulated cAMP accumulation. Pretreatment with PACAP 27, PACAP 38 or VIP equally blocked PACAP- and VIP-stimulated cAMP accumulation. These results suggest that PACAP is a more potent stimulator of cAMP accumulation than VIP in UMR 106 cells. PACAP and VIP may share a role in the paracrine or neuroendocrine regulation of bone metabolism.

Cyclic AMP↗
PubMed1996

Regulation of the anti-allograft response by targeting the CD2 antigen: a potential strategy for the creation of transplant tolerance.

Activated T cells playa central role in the rejection of histoincompatible organ allografts. Studies of trans- membrane signaling requirements ofT cells, by identifying molecular and cellular mechanisms ofT-cell activation, can lead to rational therapeutic strategies for the regulation of the anti-allograft response. A clear consensus exists that the primary signal for T-cell activation is generated as a consequence of the in- teractions among the T-cell receptor for antigen (TCR)I cluster designation 3 (CD3) complex and the antigenic peptide presented in the context of major histocompatibility complex (MHC) proteins expressed on the sur- face of the antigen-presenting cells (APCs). '-7 The TCR/CD3-dependent signaling is necessary but insufficient in itself to fully activate normal human primary (quiescent) T cells, and additional costimulatory signals are required for full activatiori.

Journal Article↗
PubMed1996

Expression of receptor protein tyrosine kinase tif is regulated during leukemia cell differentiation.

tif is a recently cloned and characterized cDNA predicting a transmembrane protein with a putative tyrosine kinase structure in its cytoplasmic domain. By analysis of the purified tif cytoplasmic domain expressed in Escherichia coli, we have demonstrated that tif is an active protein tyrosine kinase capable of autophosphorylation on tyrosine residues and this phosphorylation is inhibited by a tyrosine-specific inhibitor genistein. Northern blot analyses of various leukemia cell lines have revealed that tif mRNA expression is primarily confined to those bearing erythroid and megakaryocytic phenotypes. Megakaryocytic differentiation of K562 and HEL cells induced by phorbol 12-myristate 13-acetate is accompanied by down-regulation of tif mRNA expression. In addition, treatment of K562 and HEL with hexamethylene bis-acetamide, but not with hemin, decreases the steady-state level of tif mRNA. These combined results suggest that the receptor tyrosine kinase tif is involved in hematopoietic development.

Acetamides↗
PubMed1996

[Clinical analysis of 62 pregnant women complicated with organic heart diseases].

OBJECTIVE: To investigate the factors which effect maternal-fetal outcomes in pregnant women complicated with organic heart disease. METHOD: Clinical data of 62 pregnant cases with either rheumatic or congenital heart diseases, collected from Beijing Anzhen Hospital during 1985-1994, were analysed retrospectively. RESULTS: The prevalence of organic heart diseases in total pregnant women during the same period was 0.97%. No significant difference was found in maternal-fetal complications between the two types of heart diseases. However, the incidences of maternal heart failure, premature birth, intrauterine growth retardation were significantly higher in patients without previous surgical treatment as compared with those with previous surgical therapy, and were also higher in patients with heart function of grade III-IV in comparison with those with grade I-II. CONCLUSIONS: Patients with organic heart diseases should be treated and operated on in order to achieve grade I-II heart function before pregnancy. Cesarean section is the better choice of delivery.

Adult↗
PubMed1996

Orientational and directional selectivities of visual neurons in the superior colliculus of the cat.

Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.

Animals↗
PubMed1996

Transforming growth factor-beta 1: regulation with a TGF-beta 1 antisense oligomer.

Transforming growth factor-beta 1 (TGF-beta 1) is a member of a family of polypeptides important in embroygenesis, tissue repair and cell growth. On the other hand, TGF-beta 1 is considered to be a causative factor in organ dysfunction and in immune deregulation of AIDS. The proteoglycan decorin and anti-TGF-beta antibodies have been used to mitigate the adverse consequences of TGF-beta 1 overexpression. We describe here a novel TGF-beta 1 complementary DNA (antisense oligomer) that is specific for TGF-beta 1 genomic DNA. The TGF-beta 1 antisense oligomer, complementary to the nucleotides flanking the first transcription start site of the human TGF-beta 1 gene and phosphorothioate modified, was efficacious in: (a) constraining TGF-beta 1 promoter activity; (b) reducing TGF-beta 1 secretion; (c) preventing TGF-beta 1 dependent inhibition of DNA synthesis; and (d) inhibiting phenotypic alterations in TGF-beta sensitive A-549 human adenocarcinoma cells. Our findings, in addition to demonstrating the efficacy of the TGF-beta 1 antisense oligomer, suggest that the oligomer might be of value for the treatment of diseases in which TGF-beta 1 overexpression might play a pathogenetic role.

Adenocarcinoma↗
PubMed1996

Tumour suppressor p53 and Rb genes in human hepatocellular carcinoma.

Aberrations of the p53 and Rb tumour suppressor genes were examined in 12 human hepatocellular carcinoma (HCC)-derived cell lines from different geographic areas and 9 local HCCs by restriction fragment length polymorphisms (RFLP), polymerase chain reaction-single-strand conformation polymorphisms (PCR-SSCP) and DNA sequencing. The relationships between genetic changes and hepatitis B virus (HBV) DNA integration in samples were compared. None of the cell lines and tumours showed structural changes in the Rb gene, while 6 cell lines and 2 tumours had mutation or deletion in exons 5 to 8 of p53. Mutations include an AGG --> AGT (Arg --> Ser) transversion at codon 249 in PLC/PRF/5 and Mahlavu, an AAT --> AAA (Asn --> Cys) transversion at codon 200 in TONG/HCC, an AAG --> GAG (Lys --> Glu) transition at codon 139 in HCC-T, a CAT --> CGT (His --> Arg) transition at codon 214 in SC4, and a CCC --> CTC (Pro --> Leu) transition at codon 250 in SC8. In Huh4, an 18-bp deletion from codon 264 to 270 resulted in loss of Leu-Gly-Arg-Asn-Ser-Phe from the amino acid sequences 265 to 270, whereas Hep3B had a 7-kb deletion after exon 7 of p53. Our data indicate that whereas Rb may not have pleiotropic effects on HCC, p53 aberrations are frequently involved in hepatocarcinogenesis. Further, HBV infection appears to be unrelated to the micro-genetic changes of p53. The G to T codon-249-mutation is consistent with HCCs arising from areas at high risk for both aflatoxin B1 (AFB1) exposure and HBV infection.

Animals↗
PubMed1996

T7-promoter-based Escherichia coli expression system induced with bacteriophage M13HEP.

The bacteriophage M13HEP was constructed by cloning the T7 RNA polymerase gene into phage M13mp18 RF DNA to express T7 RNA polymerase under the control of the lac promoter. Through M13HEP phage infection, T7 RNA polymerase could be introduced into an expression strain and heterologous genes under the control of the T7 promoter can be induced to express. Using this phage M13HEP induction system, many heterologous genes, especially some genes whose products are toxic to the host strain, were successfully expressed. By transferring F' pilli from E. coli XL1-blue to E. coli HMS174, a new E. coli strain HMS174F' was obtained to make the construction, expression, and single-stranded DNA rescue of the T7 expression plasmid be conveniently performed in the same strain.

Bacteriophage M13↗
PubMed1996

[Reasons for removing mammary prostheses in 27 patients after augmentation mammaplasty].

We have performed agumentation mammplasty on 867 patients since 1989. Twenty-seven of them had their prostheses removed for various reasons including infection, pain, rupture or exposure of the implant, capsular contracture, psychopath, etc. The authors think that the proper selection of good implants and submuscular insertion of the implant are important for reducing such complications.

Adult↗
PubMed1996

[Inhibition of human poorly differentiated nasopharyngeal carcinoma cell line CNE-3 growth by antisense EB virus LMP-1 gene].

A recombinant retroviral vector containing Epstein-Barr virus (EBV) LMP1 antisense sequences was constructed to evaluate the posibility of gene therapy in nasopharyngeal carcinoma. The vector was packed with PA 317 cells as a pseudoretroviral one. Immunofluorescence examination showed it can evidently suppress the activation of B95-8 cell EBV. The inhibition rate was 71%. We have successfully using it to infect human poorly differentiated nasopharyngeal carcinoma cell line CNE-3, its growth was lowered down at a rate of 70%. The ability of clone formation in soft agar, tumorigenicity in nude mice of CNE-3 were markedly dropped. By Southern blot, there was high level of retroviral vector pZIP neo gene present in the transfection of tumor cells which confirmed that antisense virus LMP1 can suppress the growth of CNE-3 cells and the tumorigenicity in nude mice. Reversly it also confirmed the relationship between EBV and nasopharyngeal carcinoma and provided experimental basis for the gene therapy of the nasopharyngeal carcinoma.

Animals↗
PubMed1996

[Clinico-pathologic study of leiomyomatosis peritonealis disseminata].

In order to study the relationship between the clinical preseentation of leiomyomatosis peritonealis disseminata (LPD) and their pathological changes as well as the differenciation of this tumor from other tumors, clinical pathological analysis was performed on the 3 cases of LPD admitted to our hospital from 1959 to 1996. Results showed that the masses in the abdomen of all three cases were found to be multiple well circumscribed nodules protruding from the serosal surface. Histological examination revealed that the nodules were composed of interlaced bundles of smooth muscle tissue. Immunohistochemical studies found that they were positive for vimentin, desmin and actin. The results of this study indicate that LPD is a benign proliferation of smooth muscle that occurs in the abdominal cavity of women during the reproductive years of life and should be distinguished from well differentiated leiomyosarcomas.

Actins↗
PubMed1996

[The role of p53 gene during the development of human oral malignant lesions: a comparative study of p53 gene mutation with P53 protein positive immunostaining].

In order to increase the sensitivity to immunostaining in formalinfixed, paraffin-embedded tissues, we developed an immunohistochemical method by microwave heating of tissue sections instead of trypsin digestion. The results of this study showed that there was no positive P53 protein reaction in normal and hyperplastic mucousa of human mouth, whereas 90% (27/30) of cases with dysplasia, 61% (30/49) of oral squamous cell carcinomas and 86% (13/15) of regional metastatic lymph nodes were positive. And all positive reactions were localized in nuclei. Comparison of these positive results of p53 gene mutation detected by silver staining method with the results by polymerase chain reaction-single strand conformation polymorphism analysis did not reveal matched results, especially during the precancerous period. The authors analysed the causes of difference not only by methodology, but also by cell groups which had different genetic changes in tissues of precancerous lesions.

Carcinoma, Squamous Cell↗
PubMed1996

A molecular pathologic study on apoptosis in retinoblastoma and the mechanism of spontaneous regression in retinoblastoma.

OBJECTIVE: The present study was designed to prove the existence of apoptosis in retinoblastoma (Rb) and to determine the pathogenic mechanism of spontaneous regression of Rb as well as the relationship between them. METHODS: Qualitative morphological study on Rb was performed by means of light microscope, electron microscope and TdT mediated biotin-dUTP nick-end labeling (TUNEL). Quantitative study was performed by automatic image analysis technology (AIAT) stained with Feulgen reaction. RESULTS: The characteristic regressed area occurred in all 47 cases of Rb. Morphological changes observed within Rb closely resembled the apoptotic cell described by Kerr et al in 1972. Under electron microscope, details of apoptosis were observed in 7 cases of Rb: the morphological sequence of events occurred in and around the cell nucleus. The morphology of the TUNEL labeling Rb cell was various. TUNEL labeling showed more positive cells in regressed area, while fewer in advanced area. AIAT revealed that apoptosis index (AI) in regressed areas was higher than that in other areas of Rb, DNA average ploidy (DP) consisted with the histology grade of Rb, the degree of hyperdiploid (DH) in metastatic area was distinctly higher than that in other areas (P < 0.05). CONCLUSIONS 1. Morphologic evidence proved the existence of apoptosis, especially more in regressed area of Rb. 2. Apoptosis may participate in the spontaneous regression of Rb. Apoptosis contributed to the spontaneous regression of Rb. 3. Tumor growth parameters of Rb (AI, DP, DH) obtained by AIAT may be used as quantitative index for pathologic classification, the selection of clinical treatment and the prognostic evaluation.

Apoptosis↗