Search PubMed⌕ Search

Biomedical subjects

L Zhu

Publications and source records attributed to L Zhu.

At least 289 records · Page 16Linked to original sources
PubMed1998

[Clinical study on traumatic anterior instability of shoulder].

OBJECTIVE: To study the clinical diagnosis, conservative and surgical treatment of traumatic anterior instability of the shoulder. METHOD: Based on the experience in diagnosis and treatment of 41 patients, we put forward criteria for diagnosis and treatment of traumatic anterior instability of the shoulder. RESULT: Diagnostic criteria: (1) history of injury to the shoulder; (2) sharp pain in the anterior aspect of the shoulder and weakness and limitation of range of motion of the shoulder; (3) the positive apprehension sign and or anterior drawer test; (4) a Hill-Sachs bony lesion on roentgenogram and abnormal double contrast CT. TREATMENT: (1) rehabilitation program for the patients having symptoms less than 3 months and without anterior capsular rupture; (2) capsular repair and imbrication procedure for the patients having symptoms more than 3 months, or not satisfied to the rehabilitation treatment, or severe anterior capsular rupture on double contrast CT. The results of the treatment were satisfactory with average 16-month follow-up. CONCLUSION: The diagnostic criteria and the treatment principles help improve the results of treatment of shoulder injuries, further clinical study is needed for traumatic anterior instability of the shoulder.

Adult↗
PubMed1998

[Correction of mitral insufficiency with posterior annuloplasty].

OBJECTIVE: To summarize the experience in treating mitral insufficiency (MI), due to secondary annular dilation in the posterior portion of the annulus with mitral valve reconstruction. METHOD: Over the past 10 years, we performed mitral valvuloplasty with posterior annuloplasty in 35 patients, of which 27 patients were associated with congenital abnormalities, 3 patients had mild MI, 24 had moderate MI, and 8 had severe MI. Entire posterior annular plication was performed in 7 patients and partial posterior annular plication in 28. Associated subvalvulopasty was performed in 7 patients and leaflets repair reconstruction in 14. RESULT: There was no postoperative mortality. Complete correction was achieved in 21 patients (60.0%) and partial correction in 11 (31.4%). Mild and moderate insufficiency was found in 3 patients (8.6%) postoperatively. NYHA function class I was gained in 34 patients. One patient developed pulmonary hypertension and died due to right heart failure five years after operation. CONCLUSION: The results indicate that posterior annuloplasty is a safe, effective technique.

Adolescent↗
PubMed1998

[Effects of beta-endorphin on glutamate neurotoxicity].

The effects of beta-endorphin(beta-End) on monosodium glutamate(MSG) neurotoxicity were studied via morphological observation and image analysis of neuronal areas, together with the determination of intracellular free calcium concentration ([Ca2+]i) in single neuron and radioimmunoassay for beta-End contents. beta-End(1.0 mg.kg-1, s.c.) was found to obviously aggravate the neuronal injury in the arcuate nucleus of hypothalamus induced by MSG(0.5 g.kg-1, s.c.). Just as MSG increased [Ca2+]i significantly, beta-End(2.0 g.L-1) itself also increased it, though the extent of elevation was smaller than that of MSG(17.0 mg.L-1). The obvious changes of [Ca2+]i induced by both MSG and beta-End were partially reversed after pretreatment with verapamil. On the other hand, the content of beta-End in different areas of the brain were augmented following the addition of MSG and further elevated by morphine treatment. These findings suggest that the mechanisms of the enhancing effect of beta-End on glutamate neurotoxicity were linked to the aggravation on the disruption of intracellular Ca2+ homeostasis induced by MSG. Moreover, the fact that opioids promote beta-End release induced by MSG may be involved in the mechanisms as well.

Animals↗
PubMed1998

[Synthesis and vasodilative activities of benzamide derivatives].

Twenty two benzamide derivatives were synthesized of which twenty one were not reported before. Vasodilative activity screening in vitro has shown that most of the compounds possess various activities, among which compound H1, H11, H17, E1, E3 demonstrated a superior pharmacological profile to the lead compound when inhibiting effect on the noradrenaline (10(-7) mol.L-1) induced contraction of rat aortic strip was chosen as the evaluation criterion, while H7,15, E7 exerted significant inhibiting action toward 85.7 mmol.L-1 KCl induced contraction of rat aortic strip. Further evaluation assays for their KCO potentials showed that E1 might be an ATP sensitive KCO. Preliminary structure-activity relationships of this kind of aromatic amides are discussed herein.

Animals↗
PubMed1998

[Studies on QSAR of the antibacterial agents quinolones: changing the parent nucleus influenced the activity].

By the method of AM1, quantum chemistry indexes of 16 compounds of quinoline, 1,8-naphthyridine and pyrido(2,3-C)pyridazine analogues were calculated and 4 QSAR equations were obtained. The results showed that the net charge of 4-carbonyl oxygen is highly correlated with the antibacterial activity in vitro, the correlation coefficient of the regressions are high(R > or = 0.96). The antibacterial activity in vitro is strongly influenced by the coplanarity of 3-carboxylic acid and the parent nucleus. In light of this study, a new parent nucleus of isothiazoleannexed quinolizine was proposed, which is expected to have much higher activity.

Bacteria↗
PubMed1998

[Expression of human ScFv against human immunodeficiency virus type 1 gp120].

In order to generate human antibody against HIV-1, using synthetic peptide from HIV-1 gp120 v3 loop as antigen, we screened the recombinant phage antibodies by immunoaffinity and selected positive clones carrying anti-gp120 ScFv gene. The phage DNA was extracted and transformed to E. coli HB2151 that allowed to express soluble ScFv proteins by inducing of IPTG. The results of SDS-PAGE and Western blot showed that the molecular weight of the expressed product is about 28 KD and exhibited anti-c-myc activity. ELISA and Dot blot analysis displayed that the soluble ScFv specifically bound to gp120 and had a higher specificity and affinity. Competitive ELISA further demonstrated that the product was specific to gp120.

Antibodies, Viral↗
PubMed1998

[Studies on some properties of the immobilized penicillin acylase by polyacrylonitrile fibres].

The extracellular penicillin acylase from Bacillus megaterium was immobilized by coupling to derivatives of polyacrylonitrile fibres. The apparent activity of the immobilized penicillin acylase was about 2,000 u/g (dry weight). The optimal pH and temperature were 9.0 and 50 degrees C for hydrolysis of penicillin G, respectively. The immobilized enzyme was stable in the pH range of 5.5-10.3, and at the temperature below 50 degrees C. The apparent Michaelis constant Ka and Vm of the immobilization enzyme were 1.33 x 10(-2) mol/L and 2.564 mmol.min-1, respectively. The inhibition constant of phenylacetic acid acted as a competitive inhibitor for The immobilization enzyme was 0.16 mol/L. The remained activity was about 80% after operating 20 times.

Acrylic Resins↗
PubMed1997

Improved PCR assay for the detection of antigen receptor gene rearrangements.

The detection of small numbers of leukaemia cells in patients with occult disease has important clinical implications. Leukaemia is a monoclonal disease which frequently displays clonal rearrangement of the T-cell receptor gamma (TCR gamma) and/or immunoglobulin heavy chain (IgH) gene. Clone-specific junctional sequences arising as a result of these gene rearrangements provide potentially valuable targets for monitoring residual disease by the polymerase chain reaction (PCR). However, existing strategies for PCR amplification of these clone-specific rearrangements frequently lack the necessary sensitivity or specificity, due either to the small size of the target junctional region, or to interference resulting from polyclonal IgH or TCR gamma rearrangements in normal lymphocytes. We have previously described a novel PCR strategy to overcome these obstacles which is based on the design of two overlapping clone-specific PCR primers which span the junctional region. We now describe a modification to this strategy which employs relatively short clone-specific primers which further increases the level of specificity. This new method should improve the detection of residual cells, particularly in those cases displaying small junctional regions. Unlike other strategies, specificity is generated from the initial round of amplification. This non-radioactive technique should thus prove effective in monitoring residual leukaemia in patients.

Bone Marrow↗
PubMed1997

Discovery of CGS 27023A, a non-peptidic, potent, and orally active stromelysin inhibitor that blocks cartilage degradation in rabbits.

Structure-activity relationships of a lead hydroxamic acid inhibitor of recombinant human stromelysin were systematically defined by taking advantage of a concise synthesis that allowed diverse functionality to be explored at each position in a template. An ex vivo rat model and an in vivo rabbit model of stromelysin-induced cartilage degradation were used to further optimize these analogs for oral activity and duration of action. The culmination of these modifications resulted in CGS 27023A, a potent, orally active stromelysin inhibitor that blocks the erosion of cartilage matrix.

Administration, Oral↗
PubMed1997

The immunosuppressant FK506 prolongs transgene expression in brain following adenovirus-mediated gene transfer.

First generation, replication-defective adenoviral vectors are highly effective for gene transfer into the central nervous system, but the host's immune response limits the utility of this vector for possible therapy of neurological disease or long-term gene transfer studies in experimental animals. We have demonstrated the effectiveness of FK506 (tacrolimus), a powerful immunosuppressant that readily crosses the blood-brain barrier, in maintaining adenovirus-mediated reporter gene transfer following stereotaxic injection of the recombinant (AdCMVlacZ) into mouse striatum. After 28 days, beta-galactosidase expression was reduced by 75% relative to day 10 in immunocompetent animals, accompanied by an inflammatory reaction in the region of transduced cells; however, in mice receiving daily s.c. injections of FK506, beta-galactosidase activity was maintained at the 10 days post-injection level.

Adenoviridae↗
PubMed1997

Cloning and genetic mapping of wheat telomere-associated sequences.

Wheat telomere-associated sequences (TASs) were cloned using a Vectorette approach and sequenced. Reverse primers specific to the TASs were combined with labelled degenerate telomere primers in PCR reactions containing total genomic DNA as template. Amplification products were separated on sequencing gels. In total, seventeen primer combinations provided 47 polymorphic fragments. Nine of these mapped beyond the most distal RFLP markers and defined the ends of seven chromosome arms. Seven of the nine terminal fragments were derived from a 118-bp tandem repeat, indicating that subtelomeric tandem repeat sequences provide an efficient means to target chromosome ends. A telomere cloning strategy and the terminal and interstitial location of TASs are discussed.

Base Sequence↗
PubMed1997

Sheared purine x purine pairing in biology.

The Watson-Crick G x C and A x T base-paired DNA duplex has been the single most important milestone in modem molecular biology. However, it is possible that other types of stable DNA structures besides the double helix might exist, since only about 5% of the human chromosome is transcribed and expressed. Stable, four-stranded G-tetraplex DNA structures occur in the extensive tandem repeated sequences at the telomeres of chromosome. Formation of stable triplexes of the Py x Pu x Py or Pu x Pu x Py type have been implicated at the control regions of certain human genes. We review and discuss the various types of DNA duplex structures containing stable sheared base-pairs and compare their structural characteristics with that of B-DNA. Pu x Pu structural motifs are found in the highly conserved sequences at the replication origins of several single-stranded DNA viruses and in the peri-centromeric regions of human chromosomes, and may be involved in important biological functions, such as viral DNA replication and centromere formation.

Base Sequence↗
PubMed1997

Testin is tightly associated with testicular cell membrane upon its secretion by sertoli cells whose steady-state mRNA level in the testis correlates with the turnover and integrity of inter-testicular cell junctions.

Testin, a Sertoli cell secretory protein whose mRNA is predominantly expressed in the testis, was shown to become tightly associated with Sertoli cell membrane upon its secretion whose solubilization requires the use of a detergent such as SDS. In the in vitro studies using Sertoli cells cultured at high cell density, where specialized junctions were being formed, the concentration of "soluble" testin in the spent media was greatly reduced versus monolayer cultures at low cell density, where specialized junctions were absent. Conversely, the concentration of "membrane-bound" testin from detergent-solubilized Sertoli cell membrane extract was positively correlated to the existence of specialized junctions in these cultures. In normal rat testes, the level of radioimmunoassayable soluble testin in the cytosol was low. However, when the inter-testicular cell junctions were disrupted either by a drug treatment such as lonidamine in vivo or by a physical treatment in vitro such as exposing Sertoli-germ cell co-cultures where specialized junctions were formed to a hypotonic treatment, a drastic surge in the testin gene expression was noted. Thus, testin can become tightly associated with Sertoli cell membrane upon its secretion when intercellular junctions are formed. It is also a marker to monitor the integrity of inter-testicular cell junctions.

Animals↗
PubMed1997

Chromosomal regions associated with segregation distortion of molecular markers in F2, backcross, doubled haploid, and recombinant inbred populations in rice (Oryza sativa L.).

Chromosomal regions associated with marker segregation distortion in rice were compared based on six molecular linkage maps. Mapping populations were derived from one interspecific backcross and five inter-subspecific (indica/japonica) crosses, including two F2 populations, two doubled haploid (DH) populations, and one recombinant inbred (RI) population. Mapping data for each population consisted of 129-629 markers. Segregation distortion was determined based on chi-square analysis (P < 0.01) and was observed at 6.8-31.8%, of the mapped marker loci. Marker loci associated with skewed allele frequencies were distributed on all 12 chromosomes. Distortion in eight chromosomal regions bracketed previously identified gametophyte (ga) or sterility genes (S). Distortion in three other chromosomal regions was found only in DH populations, where japonica alleles were over-represented, suggesting that loci in these regions may be associated with preferential regeneration of japonica genotypes during anther culture. Three additional clusters of skewed markers were observed in more than one population in regions where no gametophytic or sterility loci have previously been reported. A total of 17 segregation distortion loci may be postulated based on this study and their locations in the rice genome were estimated.

Alleles↗
PubMed1997

A Bcl-2 antisense oligonucleotide increases alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) toxicity in cortical cultures.

Both alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor-mediated neurotoxicity and the induction of death-regulatory genes have been implicated in the pathophysiology of delayed ischemic neuronal injury. To assess the role of the antiapoptotic gene Bcl-2 in the modulation of AMPA toxicity, we exposed neuron-enriched cultures from rat cerebral cortex to AMPA, in the absence or presence of an antisense oligodeoxynucleotide (ODN) directed against Bcl-2. AMPA produced concentration-dependent toxicity detected by a decrease in fluorescence of the redox indicator Alamar blue and by an increase in lactic acid dehydrogenase release. This effect was accompanied by the induction of Bcl-2 protein expression, with maximal induction at 100 microM AMPA. A phosphorothioate antisense ODN against Bcl-2 reduced the AMPA-stimulated induction of Bcl-2 protein levels, detected by western blotting, by about 70%. In the presence of the antisense ODN, but not sense or scrambled ODNs, the toxicity of 100 microM AMPA was increased by about 60%. These findings suggest that induction of Bcl-2 expression by AMPA may have a protective role to limit AMPA receptor-mediated neuronal damage and that modifying Bcl-2 expression could have therapeutic potential in ischemia.

Animals↗
PubMed1997

Assessment of the longevity of the liver using a rat transplant model.

To assess the longevity of the liver, arterialized, orthotopic liver grafts were performed using syngeneic male BN/BiRij rats. Young (5-month-old) livers were transplanted into 5-month-old recipients (group I, n = 27), and old (28-month-old) livers were transplanted into 5-month-old rats (group II, n = 28). Recipient survival after transplantation was similar in both groups. The average age of the livers at the time of death was 16.7 months in group I and 39.1 months in group II. Four of the livers in group II survived for more than 4 years (48.1 to 52.4 months). Early deaths (less than 1 year) after transplantation were most commonly caused by biliary obstruction and cholangitis in both groups. Late deaths (more than 1 year) after grafting were mainly from heart failure or tumors. None of the animals died of liver failure or liver disease. Weight gain in the rats, total serum protein levels, and alanine transaminase levels after transplantation did not differ significantly between the two groups. There was a trend for the histological features of aging of the liver-fibrosis, bile duct proliferation, and pigment deposition-to become more prevalent as the livers became very old (mean age, 46 months). Nevertheless, typical aging changes, as individual findings, were absent in nearly half of the oldest organs. The alterations in morphology had no apparent effect on the ability of the livers to sustain the lives of the recipients. The liver of the BN/BiRij rat was capable of surviving far beyond the maximum life span of BN/BiRij rats, and rats in general. It did not become diseased in the process.

Age Factors↗
PubMed1997

Minimum length of sequence homology required for in vivo cloning by homologous recombination in yeast.

With efficient homologous recombination in Saccharomyces cerevisiae, a rapid in vivo cloning technique has been available. Here we demonstrated that 30 bp of a homologous sequence at each end of a DNA fragment is sufficient to integrate the fragment into a linearized plasmid in yeast. To obtain a high yield of recombination transformants, however, more than 60 bp are desirable. Interestingly, we observed that 20 bp of homology at one end of a DNA fragment is sufficient for efficient recombination provided that the other end contains 80 bp of homologous sequence. Some applications, including high-throughput transferring of EST inserts to the yeast expression systems for the Human Genome Project, are discussed.

Animals↗