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Biomedical subjects

L Zhao

Publications and source records attributed to L Zhao.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Replacement of the superior vena cava with vascular prosthesis in surgical treatment of lung carcinoma].

OBJECTIVE: To investigate the effect, surgical technique and prognosis of replacement of the superior vena cava(SVC) with vascular prosthesis in surgical treatment of advanced lung carcinoma. METHODS: Twenty six patients with right lung carcinoma invading the SVC (central lung carcinoma in 21 cases, peripheral lung carcinoma in 5 cases) underwent radical resection of tumor with concomitant replacement of SVC with vascular prosthesis. All patients took a low dose of anticoagulant in short-term after operation. Long-term follow-up was conducted. RESULTS: All the cases had no intraoperative or postoperative early death, and no early or late obstruction of SVC. Follow-up was conducted in 23 cases. The overall survival rates at 1, 3 and 5 years were 85%(22/26), 39%(7/18) and 36%(4/11) respectively. CONCLUSIONS: Combination of resection of tumor and replacement of SVC enabled some cases of advanced lung carcinoma to achieve complete resection. This surgical technique extended the indications of surgical treatment of lung carcinoma, and increased the survival rate of advanced lung carcinoma. Further clinical applications are recommended.

Blood Vessel Prosthesis↗
PubMed1999

[Optical coherence tomography of macular holes].

OBJECTIVE: To study the characteristics and clinical application value of the optical coherence tomography (OCT) of macular holes. METHOD: A total of 35 patients with the clinical diagnosis of macular hole were examined with OCT between September and December 1998. OCT imaging was conducted through a dilated pupil, and the OCT images were analyzed and measured. RESULTS: Of the 35 patients examined with OCT, there were pseudohole and epimacular membrane in one eye, vitreofoveal traction in one eye, macular holes in 36 eyes, and 3 patients had macular hole in bilateral eyes. In 4 eyes, there were partial-thickness macular holes, and the defect of partial thickness of neural epithelium in the fovea without halo of retinal detachment was shown in the OCT image. In 32 eyes, there were full-thickness holes; the OCT displayed complete losing of the whole thickness of the neural epithelium in the fovea, sharp edge of the hole and the halo of retinal detachment around the hole. Sometimes nonreflective cavities could be seen within the retina, and the retinal thickness around the hole was increased. According to Gass stage classification of macular hole, there were 2 eyes with impending hole, 3 eyes in stage 2, 15 eyes in stage 3 and 6 eyes in stage 4. 4 eyes underwent vitrectomy. The OCT imaging after the surgery demonstrated the closure of hole and the disappearance of halo surrounding the hole. Through quantitative measurement, the diameter of the hole was (565.88 +/- 40.35) microm, the diameter of the halo was (1,338.76 +/- 147.57) microm, and the retinal thickness surrounding the hole was (391.87 +/- 18.97) microm. The sizes of the hole and the halo and the retinal thickness around the hole were correlated with the vision. CONCLUSION: OCT is a novel noninvasive, noncontact imaging technique. It is helpful in the diagnosis and differential diagnosis of the macular hole; the progress of the hole can be quantitatively estimated, and it is also helpful in selection of operation and assessment of operative therapeutic effects.

Adult↗
PubMed1999

[A comparative analysis of clinical and pathologic diagnoses in 79 pediatric autopsy cases].

This study is a comparative analysis between pathologic and clinical diagnoses of 79 pediatric autopsy cases. We found that 14 cases were misdiagnosed. The rate of misdiagnosis is 17.72%. The 79 cases were divided into four groups of children aged approximately 28 days, approximately 5 years, approximately 10 years and approximately 14 years, the rate of misdiagnosis of the first group is 29.63%. This rate is apparently higher than other age groups(P < 0.05). The younger the age group is, the higher the chances of misdiagnosis. Respiratory disease was the main misdiagnosis rating 42.86%, while the two misdiagnosed cases were found to be tuberculosis. We suggest that doctors be aware of the perinatal factor when they diagnose newborns and try to find out the primary cause of illness, the threat of tuberculosis to children. Pediatricians should heed.

Adolescent↗
PubMed1999

[Determination of oleanolic acid and ursolic acid in spica Prunellae by derivative GC method].

OBJECTIVE: To develop a GC method to determine the oleanolic acid and ursolic acid in Spica Prunellae. METHOD: Before GC analysis, the sample was derivatized with CH2N2 solution. The GC conditions were as follows: comumn-10% SE-30(2m x 3mm) and column temperature -270 degrees C. RESULT: The two constituents were well separated and had good linearity in the range of 0.0025-0.4000 mg/ml. The average recoveries and RSD of oleanolic acid were 93.53% and 3.5%, 94.18% and 3.0% respectively. CONCLUSION: The method is good for determining oleanolic acid and ursolic acid in Chinese medicines.

Chromatography, Gas↗
PubMed1999

[Immunohistochemical detection of hepatitis C virus antigen from hepatocellular carcinoma].

To investigate the infection of HCV and the expression of HCV antigen (HCAg) in HCC, immunohistochemical protocol was performed on tumorous liver tissues from 40 patients with HCC to detect HCAg and hepatitis B virus surface antigen (HBsAg) simultaneously. The results showed that the positive rates for HCAg and HBsAg were 17.5% (7/40) and 70% (28/40) respectively. HBsAg and HCAg were simultaneously detected in six of 40 cases and only one case had HCAg positive alone in the liver tumorous tissue. The positive signals were localized in diffuse cytoplasm of hepatocytes and the positively stained cells were mainly distributed in local pattern. The results suggested that HCV infection did exist in some cases of HCC, so HCV might be a viral risk factor in addition to HBV in the genesis of HCC in China.

Adult↗
PubMed1999

[Grey relational analysis on early bolting of Angelica and its main factors].

Selecting the principal environmental and cultivated factors from the main production areas of Angelica sinensis in Gansu, the problem of early bolting were analysed with grey system theory. After the quantitative analysis, the relational grade was: elevation > precipitaton > density of crop > organic fertilizer > phosphorus fertilizer > nitrogen fertilizer. The research would provide scientific basis for check on the rate of the early bolting of Angelica effectively as well as improve the product and benefits.

Altitude↗
PubMed1999

[HBsAg expression, anti-HBs induction and pathological observation in the mice inoculated with DNA vaccine against hepatitis B].

OBJECTIVE: To study if special humoral immunological response can be induced by DNA vaccine against Hepatitis B (NV-HB/s) and its mechanism. METHODS: The Balb/C mice inoculated with NV-HB/s by intramuscular injection were detected for HBsAg(the expressed product of NV-HB/s) by ABC immunohistochemistry or ELISA, and for anti-HBs by ELISA and also performed the routine pathological examination. RESULTS: After inoculated with NV-HB/s, HBsAg could be detected from mice muscle tissue samples of injected sites one week later and almost kept positive(75% and even more) up to 6th month, but was undetectable from all the serum samples during this period; anti-HBs could be detected from serum samples of some mice two weeks later and of all the mice detected one month later, it still kept positive at 6th month while the mice were sacrificed. Under microscope, only non-specific inflammation was found in the muscle tissues of injected sites and could completely recover within 4 weeks, no matter whether the mice were inoculated with NV-HBs, or with traditional HB vaccine derived from blood, or even with PBS as control. CONCLUSION: DNA vaccine against Hepatitis B (NV-HB/s) can successfully express HBsAg in the muscle tissue of mice by intramuscular inoculation and subsequently induce anti-HBs in vitro.

Animals↗
PubMed1998

Telomerase is controlled by protein kinase Calpha in human breast cancer cells.

Telomerase, a specialized RNA-directed DNA polymerase that extends telomeres of eukaryotic chromosomes, is repressed in human somatic tissues and becomes activated during tumor progression in most human cancers. To date, little is known about how telomerase is activated and controlled in cancer, although activation is thought to be involved in cancer cell immortalization. Here, we report that human telomerase-associated protein 1 (hTEP1) and the telomerase catalytic subunit (human telomerase reverse transcriptase (hTERT)) are phosphoproteins and that their phosphorylation is a prerequisite for the activation of telomerase in intact human breast cancer cells. Identified by hTEP1 peptide affinity chromatography, protein kinase Calpha mediates the phosphorylation of hTEP1 and hTERT and induces a marked increase in telomerase activity. Thus, phosphorylation of hTEP1 and hTERT by protein kinase Calpha represents an essential step in the generation of a functional telomerase complex in the initiation and maintenance of telomerase activity in human cancer.

Amino Acid Sequence↗
PubMed1998

Promiscuous coupling of receptors to Gq class alpha subunits and effector proteins in pancreatic and submandibular gland cells.

Mice with deficiencies in one or more Gq class alpha subunit genes were used to examine the role of the alpha subunit in regulating Ca2+ signaling in pancreatic and submandibular gland cells. Western blot analysis showed that these cells express three of the four Gq class subunits, Galphaq, Galpha11, and Galpha14 but not Galpha15. Surprisingly, all parameters of Ca2+ signaling were identical in cells from wild type and four lines of mutant mice: 1) Galpha11-/-, 2) Galpha11-/-/Galpha14-/-, 3) Galpha14-/-/Galpha15-/-, and 4) Galphaq-/-/Galpha15-/-. These parameters included the Kapp for several Gq class coupled receptors, induction of [Ca2+]i oscillations by weak stimulation, and a biphasic [Ca2+]i response by strong stimulation. Furthermore, Ca2+ release from internal stores and Ca2+ entry were not affected in cells from any of the mutant mice. We conclude that Galphaq, Galpha11, and Galpha14 promiscuously couple several receptors (m3 muscarinic, bombesin, cholecystokinin, and alpha1 adrenergic) to effector proteins that activate both Ca2+ release from internal stores and Ca2+ entry.

Animals↗
PubMed1998

A gene cluster for macrolide antibiotic biosynthesis in Streptomyces venezuelae: architecture of metabolic diversity.

In a survey of microbial systems capable of generating unusual metabolite structural variability, Streptomyces venezuelae ATCC 15439 is notable in its ability to produce two distinct groups of macrolide antibiotics. Methymycin and neomethymycin are derived from the 12-membered ring macrolactone 10-deoxymethynolide, whereas narbomycin and pikromycin are derived from the 14-membered ring macrolactone, narbonolide. This report describes the cloning and characterization of the biosynthetic gene cluster for these antibiotics. Central to the cluster is a polyketide synthase locus (pikA) that encodes a six-module system comprised of four multifunctional proteins, in addition to a type II thioesterase (TEII). Immediately downstream is a set of genes for desosamine biosynthesis (des) and macrolide ring hydroxylation. The study suggests that Pik TEII plays a role in forming a metabolic branch through which polyketides of different chain length are generated, and the glycosyl transferase (encoded by desVII) has the ability to catalyze glycosylation of both the 12- and 14-membered ring macrolactones. Moreover, the pikC-encoded P450 hydroxylase provides yet another layer of structural variability by introducing regiochemical diversity into the macrolide ring systems. The data support the notion that the architecture of the pik gene cluster as well as the unusual substrate specificity of particular enzymes contributes to its ability to generate four macrolide antibiotics.

Anti-Bacterial Agents↗
PubMed1998

Relative importance of cytotoxic T lymphocytes and nitric oxide-dependent cytotoxicity in contractile dysfunction of rejecting murine cardiac allografts.

BACKGROUND: Previous in vitro studies have suggested that both cytotoxic T lymphocyte (CTL)-mediated and non-CTL-mediated myocyte lysis occur during murine cardiac heterotopic allograft rejection, but the relative importance of these injury mechanisms on myocardial function is not established. We therefore compared the in vivo effects of depletion of CTL and inhibition of nitric oxide synthase (NOS) on contractility of the rejecting heart. METHODS: Syngeneic (BALB/c into BALB/c) and allogeneic (BALB/c into C57/B16) heterotopic abdominal cardiac transplants were performed. In some of the allogeneic transplants, CD8+ lymphocytes were depleted by intraperitoneal injection of anti-CD8 monoclonal antibody. NOS inhibition was accomplished by continuous infusion of NG-monomethyl-L-arginine via a subcutaneous osmotic pump. Five days after transplantation, the abdominal cavity was opened and the transplanted heart exposed. Base to apex developed force was measured during spontaneous beating at a diastolic stretch of 4 g by placing a suture through the apex of the heart and attaching it to a strain gauge. Effects of interventions on graft survival were determined by recording the days required for loss of palpable graft contractions. RESULTS: Allogeneic hearts showed a significant reduction in systolic force compared to non-rejecting syngeneic hearts. Depletion of CD8+ cells improved contractility significantly relative to non-depleted allogeneic hearts, but contractility remained significantly reduced relative to syngeneic hearts. Developed force in allogeneic hearts was also improved by NOS inhibition (P<0.01), and NG-monomethyl-L-arginine infusion slightly prolonged graft survival. CONCLUSION: Both CTL-mediated and NOS-dependent (possibly macrophage-mediated) mechanisms contribute to contractile dysfunction during early cardiac allograft rejection in this model. However, NOS inhibition combined with CTL depletion only slightly prolongs graft survival in this model.

Animals↗
PubMed1998

A lambda 3' enhancer drives active and untemplated somatic hypermutation of a lambda 1 transgene.

Somatic hypermutation is a highly regulated process that targets mutations to the rearranged Ig genes. Little is known about the cis-elements required for somatic hypermutation of the lambda light chain gene. We have studied somatic hypermutation of a rearranged lambda 1 transgene under the control of either a lambda 2-4 or kappa 3' enhancer. The mutations in the transgenes were analyzed by sequencing DNA amplified from hypermutating Peyer's patch B cells. The results indicate that the lambda 3' enhancer can drive active hypermutation of a lambda 1 transgene in Peyer's patch cells. The lambda 1 transgene under analysis carried two marked V lambda 2 genes immediately upstream that could serve as sequence donors in possible gene conversion events. There was no evidence of sequence transfer to the hypermutated lambda 1 gene, suggesting that gene conversion is not a major mechanism for somatic hypermutation in mice.

Animals↗
PubMed1998

The structures of the mouse and human urocortin genes (Ucn and UCN).

The mouse and human urocortin genes (Ucn and UCN, respectively) have been isolated, characterized, and found to have very similar structures. Each has two exons, and the entire coding region is located in the second exon, as is the case for the gene of the related peptide, corticotropin-releasing factor. Several putative transcription factor-binding sites were identified in each of the urocortin promoters, including a TATA box, a cyclic AMP response element (CRE), GATA-binding sites, and a C/EBP-binding site as well as a Brn-2-binding site(s). Sequence analyses of the mouse and human genes also revealed the presence of a previously identified gene, Mpv17, in the 5' region upstream of the urocortin gene. Functional studies following transient transfection of urocortin reporter plasmids in PC12 cells revealed that the urocortin promoter is controlled by both positive and negative elements; the CRE is important for basal activity as well as responsiveness to forskolin stimulation.

Alleles↗
PubMed1998

Vi-deficient and nonfimbriated mutants of Salmonella typhi agglutinate human blood type antigens and are hyperinvasive.

We generated nonfimbriated mutants from both Vi-positive and -negative Salmonella typhi to analyze the role of type 1 fimbriae and Vi-antigen in bacterial invasion. A Vi-defective mutant of S. typhi GIFU 10007-3 was more invasive than the wild-type strain GIFU 10007. The wild-type strain expressing Vi-antigen did not agglutinate both Saccharomyces cerevisiae and human erythrocytes but Vi-defective mutants were able to agglutinate S. cerevisiae and human erythrocytes. Nonfimbriated mutants from Vi-negative GIFU 10007-3 lost the ability to adhere to S. cerevisiae but still could agglutinate human erythrocytes. The Vi-negative mutant increased secreted proteins and became 5-fold more invasive than the wild-type strain. Nonfimbriated Vi mutants became 50-120-fold more invasive than the wild-type GIFU 10007. To determine why nonfimbriated Vi mutants still agglutinate human red blood cells, we searched bacterial proteins that could bind human blood-type antigens. We finally identified a candidate 37 kDa outer membrane protein that recognized fucosyl-galactose, a structure common to blood type A, B and H antigens.

ABO Blood-Group System↗
PubMed1998

Salmonella typhi rpoS mutant is less cytotoxic than the parent strain but survives inside resting THP-1 macrophages.

Transcription of the stationary-phase sigma factor RpoS of Salmonella typhi increased in the macrophage. A single rpoS mutant of S. typhi was constructed to analyze the role of RpoS in intracellular multiplication of the bacterium and host cell killing. This mutant was sensitive to starvation, low pH and hydrogen peroxide; however, it could still multiply inside resting macrophages and was less cytotoxic than the wild-type strain. Therefore, S. typhi might produce RpoS-dependent factors which could contribute to host cell death.

Bacterial Proteins↗
PubMed1998

Infection with Chlamydia pneumoniae accelerates the development of atherosclerosis and treatment with azithromycin prevents it in a rabbit model.

BACKGROUND: Chlamydia pneumoniae infection has been associated with atherosclerosis by serological studies and detection of bacterial antigen within plaque. We sought to evaluate a possible causal role in an animal model. METHODS AND RESULTS: Thirty New Zealand White rabbits were given three separate intranasal inoculations of either C pneumoniae (n = 20) or saline (n = 10) at 3-week intervals and fed chow enriched with a small amount (0.25%) of cholesterol. Immediately after the final inoculation, infected and control rabbits were randomized and begun on a 7-week course of azithromycin or no therapy. Three months after the final inoculation, rabbits were euthanatized and sections of thoracic aortas were blindly evaluated microscopically for maximal intimal thickness (MIT), percentage of luminal circumference involved (PLCI), and plaque area index (PAI) of atherosclerosis. Vascular chlamydial antigen was assessed by direct immunofluorescence. MIT differed among treatment groups (P=.009), showing an increase in infected rabbits (0.55 mm; SE = 0.15 mm) compared with uninfected controls (0.16 mm; SE = 0.06 mm) and with infected rabbits receiving antibiotics (0.20 mm; SE = 0.03 mm) (both P<.025), whereas MIT in infected/treated versus control rabbits did not differ. PLCI also tended to differ (P<.1) and PAI differed significantly (P<.01) among groups with a similar pattern. Chlamydial antigen was detected in 2 untreated, 3 treated, and 0 control animals. CONCLUSIONS: Intranasal C pneumoniae infection accelerates intimal thickening in rabbits given a modestly cholesterol-enhanced diet. In addition, weekly treatment with azithromycin after infectious exposure prevents accelerated intimal thickening. These findings strengthen the etiologic link between C pneumoniae and atherosclerosis and should stimulate additional animal and human studies, including clinical antibiotic trials.

Animals↗
PubMed1998

Rigid phencyclidine analogues. Binding to the phencyclidine and sigma 1 receptors.

Three phencyclidine (PCP) analogues possessing a highly rigid carbocyclic structure and an attached piperidine ring which is free to rotate were synthesized. Each analogue has a specific fixed orientation of the ammonium center of the piperidinium ring to the centrum of the phenyl ring. The binding affinities of the rigid analogues 1-piperidino-7,8-benzobicyclo[4.2.0]octene (14), 1-piperidinobenzobicyclo[2.2.1]heptene (16), and 1-piperidinobenzobicyclo[2.2.2]octene (13) for the PCP receptor ([3H]TCP) and th-receptor (NANM) were determined. The three analogues show low to no affinity for the PCP receptor but good affinity for the th-receptor and can be considered th-receptor selective ligands with PCP/th ratios of 13, 293, and 368, respectively. The binding affinities for the th-receptor are rationalized in terms of a model for the th-pharmacophore.

Animals↗