Biomedical subjects

G Liang

Publications and source records attributed to G Liang.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Arthropod diversity in leafy vegetable field and sampling technology].

Two sampling units (plant and quadrat) and two sampling methods (random and fixed) were adopted to compare the variation degree of the diversity of arthropod communities in different chinese cabbage fields. The results show that a lower variation degree was found when the random sampling method was adopted with quadrat (0.11 m2) as sampling unit at seedling stage and with plant as sampling unit from growing to mature stage. The community diversity was relatively steady, when the critical number of samples was more than 12 quatrats (0.11 m2) at seedling stage, 30 plants in growing period, and 20 plants at mature stage. The optimum sampling unit, sampling method and sampling number of arthropod diversity in leafy vegetable field were also determined.

Animals↗

PubMed2000

[Lifetable of cotton bollworm under different control condition].

The lifetables of 3rd and 4th generation of cotton bollworm Helicoverpa armigera Hubner were established by action factors under four different control conditions. The results showed that under natural control, the egg parasitic rates of 3rd and 4th cotton bollworm were 4.39% and 1.19%, the predatory rates were 21.11% and 15.80%, and the larvae parasitic rates were 19.34% and 16.20% respectively. The indexes of population trend were only 0.0032 and 0.0014 respectively, after using selective pesticides IKI and Bt to control cotton bollworm. Though the index of population trend decreased to 48.66% and 61.67% after contantly praying chemical pesticides, the number of predators also decreased to 23.48% and 41.26% respectively. Transgenic Bt cotton could inhibit the population increase of cotton bollworm, but had no effect on predators. The parasitic rates of 3rd and 4th cotton bollworm on Transgenic Bt cotton were 51.14% and 0% respectively, as compared to control.

Animals↗

PubMed2000

[Epizootic dynamics of Spodoptera litura nuclear polyhedrosi virus].

Through investigation of tracking infected Spodoptera litura larvae, the epizootic dynamics of S. litura nuclear polyhedrosis virus(SlNPV) in field was studied with different dosages of SlNPV. The results showed that in the range of virus dosages (3.1 x 10(5)-3.1 x 10(8) PIBs.ml-1), the initial infection syndrome was observed after 4 days of treatment, and peaked in 5-7 days. The larvae mortality occurred after 5-6 days of treatment, and peaked in 6-8 days. The prevalence peak of host was basically coincident to the incidence peak. The distribution of diseased incidence of hosts and disease death time could be quite simulated by time-dosage-mortality model(TDM). Hosmer-Lemoshow test showed that the predicted values well fitted with observed data, and t-test indicated the parameters of the model reached significant level(P < 0.0001). The distribution of diseased prevalence was simulated by Holliday model, the regression of function was significant by F-test, and the parameters of the model reached or approached significant level(p < 0.005). TDM model could be used to predict the daily incidence, prevalence, disease death rate of present generation population of host pest.

Animals↗

PubMed2000

Molecular epidemiologic study of Mycoplasma genitalium infection in high risk populations of sexually transmitted diseases in China.

OBJECTIVE: To detect Mycoplasma genitalium (Mg) infection in high risk populations of sexually transmitted diseases (STDs) from several cities in China and to clarify the possible role of Mg in the pathogenesis of non-gonococcal urethritis. METHODS: Polymerase chain reaction (PCR) based on 2 pairs of primers, one for Mg-Pa (adhesion protein) and the other for 16S-rRNA (Mycoplasma genera) was used to detect Mg infection. Urogenital specimens of different high risk populations and urethritis patients, were collected from the Guangdong, Kunming, Shanghai, Nanjing, and Changzhou areas. RESULTS: The positive detection rate of Mg-DNA in high risk populations of STDs was significantly higher than that of the control group (chi 2 = 7.82, P < 0.01). The positive detection rates in Guangdong STD clinics and promiscuous persons from Kunming were higher than those from the Shanghai, Nanjing, and Changzhou areas (chi 2 = 8.54, P < 0.01 and chi 2 = 5.89, P < 0.05). Mg DNA could be detected in those patients without other relevant pathogens. Some patients were simultaneously infected with Mg and other microbes, such as Chlamydia trachomatis and/or Ureaplasma urelyticum. The positive Mg-DNA detection rate in patients with urethritis symptoms was higher than in patients without the symptoms (chi 2 = 11.68, P < 0.01). CONCLUSION: Mg infection exists in high risk populations of STDs in China, and the Mg infection rate is different among different high risk groups.

Adolescent↗

PubMed2000

[Laboratory study on protective and therapeutic effects of pinacidil on pulmonary vascular remodeling in rats with hypoxia-induced pulmonary hypertension].

OBJECTIVE: To investigate the protective and therapeutic effects of pinacidil on hypoxia-induced pulmonary hypertension(HPH) and pulmonary vascular remodeling. METHODS: 46 male Wister rats were divided into control group, hypoxic group and treated group (hypoxic rat treated with pinacidil for 4 weeks). Rat models with chronic HPH were established by chronic hypobaric hypoxia [(10 +/- 0.5)% O2, 4 weeks)]. The mean pulmonary arterial pressure (mPAP) and right ventricle/left ventricle and septum [RV/(LV + S)] were measured and the small pulmonary arterial morphologic changes were observed with morphmetric analysis under microscopes in three groups. RESULTS: (1) The level of mPAP(28.4 +/- 2.8) mm Hg and RV/(LV + S) (0.30 +/- 0.03) were significantly higher in the hypoxic group than (16.2 +/- 1.8) mm Hg and (0.22 +/- 0.03) in control group respectively (P < 0.01). Morphometry investigation showed that the external diameter became smaller and that ratio of vascular wall thickness to external diameter (MT%) (25.7 +/- 2.6)% and ratio of vascular wall area to total area (MA%) (75.3 +/- 5.6)% significantly increased in the hypoxic group. (2) The mPAP(23.3 +/- 2.6) mm Hg, RV/(LV + S) (0.27 +/- 0.04) and pulmonary vascular pathologic changes MT%(22.1 +/- 2.5)% and MA% (67.0 +/- 6.1)% significantly decreased in the treated group, indicating that pinacidil inhibited HPH and hypoxia-induced thickening and muscularization of small pulmonary arteria. CONCLUSION: Pinacidil may partly prevent the development of HPH and pulmonary vascular remodeling.

Animals↗

PubMed2000

[Clinical significance on protruded nucleus pulposus: a comparative study of 44 patients with lumbar intervertebral disc protrusion and 73 asymptomatic control in tridimentional computed tomography].

OBJECTIVE: To probe the clinical significance of space occupation of lumbar protruded nucleus pulposus (PNP) in vertebral canal. METHODS: Materials of tridimentional ultrathin scanning computed tomography (CT), plain and flexion-extension dynamic radiograph on lumbar spine in 44 patients of lumbar intervertebral disc protrusion and 73 asymptomatic subjects (as control, including 22 cases with PNP but without symptoms) were observed, analysed and compared in volume, surface area, relative space occupation of PNP inside spinal canal, structure deformation and mobility of lumbar spine, and their difference and relevance. RESULTS: The rate of asymptomatic lumbar disc protrusion in the control group was up to 30.1%. The volume, surface area and relative space occupation of PNP inside spinal canal in the patients group were significantly higher than those in the control group. Although the structure was more deformed and mobility of lumbar spine more limited in the patients group before and after treatment than those in the control group, as compared with those subjects with asymptomatic PNP, the difference was insignificant. CONCLUSION: (1) Relative space occupation of PNP inside spinal canal could be usually digested by compensation system of spinal column, however, there is no final conclusion reached about the limit of compensation system; (2) Relatively bigger PNP may reduce the structure compensation capability of lumbar spine, which will result, sometimes, in a mechanical disorder of lumbar spine and nerve root irritation.

Adult↗

PubMed2000

[Complications of massive allografts after segmental resection of malignant bone tumors].

OBJECTIVE: To analyze the postoperative complications of bone and joint allografting for the reconstruction of massive bone defect after the resection of malignant bone tumors and its management. METHODS: Bone-joint allografting for the reconstruction of massive bone defect after the resection of malignant bone tumors with different internal fixations was performed in 106 patients with complete follow-up data. Bone healing time, complication rate, and final results in different allografts were compared. Operation indications, complications and internal fixation were also analyzed. The final results were determined according to the Mankin's standard. RESULTS: Allografts Alcohol immersed were more susceptible to infection, non-union, etc. Allografts and combined prosthesis were superior to semi-articular transplantation. Complications included deep infection (10%), skin necrosis (12.2%), local recurrence (14.4%), and delayed union or non-union (15.6%). Dynamic interlocked intramedullary nailing was superior to conventional intramedullar nailing and compression plates. CONCLUSIONS: Allografting is acceptable for the reconstruction of massive bone defect after tumor resection. Its results are encouraging after proper management of complications caused by surgical technique, internal fixation and soft tissue repair.

Adolescent↗

PubMed1999

Aminoisoquinolines: design and synthesis of an orally active benzamidine isostere for the inhibition of factor XA.

The design, synthesis and SAR of sulfonamidopyrrolidinone fXa inhibitors incorporating a new benzamidine isostere, namely aminoisoquinolines, is described. These inhibitors have higher Caco-2 cell permeability than comparable benzamidines and attain higher levels of exposure upon oral dosing. The most potent member 14b (fXa Ki=6 nM) is selective against other serine proteases of interest (>600 fold).

Administration, Oral↗

PubMed1999

The human DNA methyltransferases (DNMTs) 1, 3a and 3b: coordinate mRNA expression in normal tissues and overexpression in tumors.

DNA methylation in mammals is required for embryonic development, X chromosome inactivation and imprinting. Previous studies have shown that methylation patterns become abnormal in malignant cells and may contribute to tumorigenesis by improper de novo methylation and silencing of the promoters for growth-regulatory genes. RNA and protein levels of the DNA methyltransferase DNMT1 have been shown to be elevated in tumors, however murine stem cells lacking Dnmt1 are still able to de novo methylate viral DNA. The recent cloning of a new family of DNA methyltransferases (Dnmt3a and Dnmt3b) in mouse which methylate hemimethylated and unmethylated templates with equal efficiencies make them candidates for the long sought de novo methyltransferases. We have investigated the expression of human DNMT1, 3a and 3b and found widespread, coordinate expression of all three transcripts in most normal tissues. Chromosomal mapping placed DNMT3a on chromosome 2p23 and DNMT3b on chromosome 20q11.2. Significant overexpression of DNMT3b was seen in tumors while DNMT1 and DNMT3a were only modestly over-expressed and with lower frequency. Lastly, several novel alternatively spliced forms of DNMT3b, which may have altered enzymatic activity, were found to be expressed in a tissue-specific manner.

Alternative Splicing↗

PubMed1999

Novel endothelin B receptor transcripts with the potential of generating a new receptor.

Using RT-PCR and rapid amplification of 5' cDNA ends (5' RACE), we have cloned three previously unrecognized endothelin B receptor (EDNRB) transcripts from a human melanoma cell line. Three distinct types of cDNAs (EDNRBDelta1, Delta2 and Delta3) were identified. EDNRBDelta1 starts upstream of the published transcription start site of hEDNRB without splicing, whereas, EDNRBDelta2 and EDNRBDelta3 are alternatively spliced. EDNRBDelta1 and EDNRBDelta2 share the same transcription initiation site and are 560bp upstream of the conventional hEDNRB, whereas that of EDNRBDelta3 is 939bp upstream from that described for the conventional hEDNRB. Interestingly, many transcription factor motifs are detectable in the upstream regions of these transcription initiation sites. The predicted amino acid sequences reveal that EDNRBDelta1 and EDNRBDelta2 produce the same protein as the conventional hEDNRB, but EDNRBDelta3 would give rise to additional in-frame 89- or 83-amino-acid residues at the N-terminus. EDNRBDelta3 generates the same amino acid sequence at the C terminus, but utilizes the polyadenylation signal within the open reading frame, resulting in a shorter 3'UTR. These transcripts are widely expressed in human tissues, but their expression patterns vary between different tissues.

3' Untranslated Regions↗

PubMed1999

Isolation and identification of Mycoplasma genitalium from high risk populations of sexually transmitted diseases in China.

OBJECTIVE: To investigate Mycoplasma genitalium (Mg) infection in high risk populations of sexually transmitted diseases (STDs) in China by means of culture, Mg-DNA detection, observation under an electron microscope (EM) and an atomic force microscope (AFM). METHODS: 227 urogenital specimens taken from both patients in clinics and high risk populations of STDs in Beijing, Nanjing and Shanghai areas were cultured in SP-4 medium for isolation of Mg. Suspicious positive strains were identified first by PCR technique which could amplify the special DNA fragments of Mg adhesion protein (Mg-Pa) and 16S-rRNA sequences. The morphologic features of Mg were observed under EM and AFM. RESULTS: Eight strains were isolated from the 227 specimens, the total positive rate was 3.52%. The isolated strains met the criteria of growth and metabolic conditions required by Mg. Specific fragments of Mg-DNA (374 bp based on Mg-Pa and 402 bp on 16S-rRNA primers, respectively) could be amplified from both the isolates and the genital secretions. Under EM and AFM, Mg showed different shapes, including flask, pear, spindle and globe shape. The typical shape of Mg was flask or pear shape with projecting neck portion and broadened terminal structure under EM and with constrictive ring between the neck and body under AFM. CONCLUSION: Mg infection exists in high risk populations of STDs in China. We highly suggest the use of AFM in dermatological study.

Cervix Uteri↗

PubMed1999

[Screening of acidic xylanase producing strain and studies on its enzyme production conditions].

From 150 fungal strains, the authors found 8 strains contained mainly of xylanase activity over 100 U/mL in which the No. 149 strain was the highest xylanase producer. Which tentatively identified as Aspergillas niger. The appropriate medium composition was as follows: wheat bran hemicellulose 4%; NaNO3 1%; wheat bran 1% prepared in Mandels nutritional solution without (NH4)2SO4 and urea. After cultivated in shake-flask at 28 degrees C-32 degrees C for 60 h, the activity reached the highest value of 357.2 U/mL. The optimum pH of xylanase was 4.6 and it was stable at pH3-11. The fermented broth of strain 149 contained in addition to xylanase (relative activity 100) also included amylase(1.8), mannanase(0.98), beta-xylosidase(0.94) and cellulase(0.17).

Aspergillus niger↗

PubMed1999

[Complete nucleotide sequence of the nonstructural gene of alphavirus YN87448 strain isolated in China and its relationship to other Sindbis viruses].

OBJECTIVE: To determine the complete nucleotide sequence of the nonstructural gene of YN87448 virus stain which was firstly isolated from a female patient with fever in Yunnan Province in 1986, and identified as a member of Alphavirus by the serological method. METHODS: The complete nucleotide sequence of the nonstructural region gene of YN87448 virus strain was determined with nine clones, which were obtained by using reverse transcription and polymerase chain reaction (RT-PCR), and by linking nine overlapping fragments into pGEM-T vector respectively. RESULTS: The complete nucleotide sequence of nonstructural gene of YN87448 virus strain was 7,613 nucleotides long exclusive of the 5' cap, encoding four nonstructural proteins, nsP1, nsP2, nsP3, nsP4, and contained one initiator(ATG) and two stop codons (TGA). In comparison with the consensus sequence of S.A.AR86, the homogeneity of the nucleotide sequence between YN87448 virus strain and sindbis-like virus isolate S.A.AR86 was 98.8%. YN87448 virus strain can not produce a fatal disease in adult mice. In comparison with the consensus sequence of S.A.AR86, there is a 54 nucleotide insertion from 5,256 bp to 5,309 bp, 3 nucleotide (AGT) deletion at 5,603 bp in nsP3 region, and an opal termination codon between the nsP3 and the nsP4 genes in YN87448. virus strain. This sequence has been put into Gene Bank and No. is AF103734. CONCLUSION: YN87448 is a new sindbis-like virus strain.

Alphavirus↗

PubMed1998

DNA methylation differences associated with tumor tissues identified by genome scanning analysis.

Most investigations on the role of DNA methylation in cancer have focused on epigenetic changes associated with known tumor suppressor genes. This may have led to an underestimation of the number of CpG islands altered by DNA methylation, since it is possible that a subset of unknown genes relevant to cancer development may preferentially be affected by epigenetic rather than genetic means and would not be identified as familial deletions, mutations, or loss of heterozygosity. We used a recently developed screening procedure (methylation-sensitive arbitrarily primed-polymerase chain reaction to scan genomic DNA for CpG islands methylated in white blood cells (WBCs) and in tumor tissues. DNA methylation pattern analysis showed little interindividual differences in the WBCs and normal epithelium (adjacent to colon, bladder, and prostate cancer cells), but with some tissue-specific differences. Cancer cells showed marked methylation changes that varied considerably between different tumors, suggesting variable penetrance of the methylation phenotype in patients. Direct sequencing of 8 of 45 bands altered in these cancers showed that several of them were CpG islands, and 2 of these sequences were identified in GenBank. Surprisingly, three of the bands studied corresponded to transcribed regions of genes. Thus, hypermethylation of CpG islands in cancer cells is not confined to the promoters of growth regulatory genes but is also found in actively transcribed regions.

Base Sequence↗

PubMed1998

Novel cyclic compounds as potent phosphodiesterase 4 inhibitors.

The synthesis and biological activity of a novel series of 2, 2-disubstituted indan-1,3-dione-based PDE4 inhibitors are described. This structurally unique class of PDE4 inhibitors is markedly different from the known PDE4 inhibitors such as RP 73401 (2) and CDP 840 (3). Structure-activity relationship (SAR) studies led to the identification of inhibitors with nanomolar potency and oral activity in a murine endotoxemia model for TNF-alpha inhibition. Unlike other classical PDE4 inhibitors, several analogues were found to be nonemetic in a canine emesis model at intravenous doses of up to 3 mg/kg.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1998

[Diagnostic significance of topical image of infrared thermograph on the patient with lumbar intervertebral disc herniation--a comparative study on 45 patients and 65 normal control].

OBJECTIVE: To analyse and explore the diagnostic significance of infrared thermography on the patients with lumbar intervertebral disc protrusion. METHODS: Forty-five hospitalized cases under conservative treatment (mainly manipulation) and 65 controls were sequentially selected. Both groups were examined with infrared thermograph on lower back and lower extremities as well as physical examination before and after treatment. The study statistically analysed the temperature difference between the involved and healthy parts at different areas; and also compared the change of the temperature difference after the treatment to the decreasing scores of physical examination afterward. RESULTS: The statistic result showed that the temperature difference between two sides on patients group was significantly higher than those of control group. The further analysis shows that the temperature difference at posterior femur area in the patient's group correlated significantly to the severity of clinical signs caused by nerve root irritation. CONCLUSIONS: The thermograph could only be considered as a reference in the diagnosis of lumbar disc protrusion. It is helpful to discover the severity of radical signs according to the posterior femoral region of hypo- (or hyper) thermogram.

Adult↗

PubMed1998

[The target--gene expression of interleukin--12 in HepG2 cells].

EB virus vector pEBAF, which contains human alpha-fetoprotein gene promoter and enhancer was used as expression vector. Two recombinant expression vectors, pEBAF/P35 and pEBAF/P40, were constructed and co-transfected into 4 cell lines. RT-PCR suggested that both P35 and P40 mRNA are expressed in HepG2 cell secreting alpha-fetoprotein, in contrast, neither P35 mRNA nor P40m RNA was expressed in non-secreting alpha-fetoprotein cell lines. This proved that the pEBAF may lead to target--expression of IL-12 in hepatoma and has tissue specificity and exclusiveness for hepatoma. The cotransfected Hyg resistant clone of HepG2 cell was selected. Northern blot indicated that the HepG2 cell clone had transcription of P35 mRNA and P40 mRNA. Expression of IL-12 in the supernatant of HepG2 cell culture had been testified by ELISA and Western blot. IL-12 biological activity test indicated that the expressed IL-12 had activity of inducing IFN-gamma production. This research laid the foundation to develop an in vivo gene therapy strategy pointing to the treatment of hepatocellular carcinoma, with selective killing of the tumor cells and no effect on the normal hepatic cells.

Carcinoma, Hepatocellular↗

PubMed1997

Characterization of human activating transcription factor 4, a transcriptional activator that interacts with multiple domains of cAMP-responsive element-binding protein (CREB)-binding protein.

We demonstrate that human activating transcription factor 4 (hATF4), a member of the activating transcription factor/cAMP-responsive element-binding protein (ATF/CREB) family of transcription factors, is a potent transcriptional activator in both mammalian cells and yeast. The N-terminal 113 amino acids of hATF4 activate transcription efficiently, and unexpectedly, the C-terminal bZip DNA binding domain of hATF4 also activates transcription, albeit weakly. Our results indicate that hATF4 interacts with several general transcription factors: TATA-binding protein, TFIIB, and the RAP30 subunit of TFIIF. In addition, hATF4 interacts with the coactivator CREB-binding protein (CBP) at four regions: 1) the KIX domain, 2) a region that contains the third zinc finger and the E1A-interacting domain, 3) a C-terminal region that contains the p160/SRC-1-interacting domain, and 4) the recently identified histone acetyltransferase domain. Interestingly, both the N-terminal and C-terminal regions of hATF4 interact with the above general transcription factors and CBP, providing a mechanistic explanation for their ability to activate transcription. Consistent with its role as a coactivator, CBP potentiates the ability of hATF4 to activate transcription. The potential significance of the interaction between hATF4 and multiple factors is discussed.

Activating Transcription Factor 4↗