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Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 469 records · Page 26Linked to original sources
PubMed1992

[Correlation between synaptic protein phosphorylation in hippocampi and shuttle box avoidance behavior].

The present investigation was undertaken to detect whether protein phosphorylation levels of hippocampal synaptosomes in mice trained on shuttle box avoidance task would show some changes. The synaptosomes were prepared at different times after the conclusion of training and labelled with gamma-32P-ATP for in vitro determination. The results are as follows: (1) No significant differences were found in the phosphorylation of synaptosomal proteins in different brain areas in normal mice before training. (2) Immediately after the conclusion of shuttle box avoidance task there appears a correlation between protein phosphorylation levels in hippocampal synaptosomes and the degree of success of training. (3) 24 h after the completion of training the above relationship is more significant, and protein phosphorylation levels of right hippocampus in Good Score Group is markedly higher than that of left one, but in the Inferior Score Group, the left-right difference is reverse. The formation of such asymmetry in protein phosphorylation in hippocampi is unknown. These data indicate that the synaptic protein phosphorylation in hippocampi might be a molecular mechanism of acquisition.

Animals↗
PubMed1991

Isolation of a yeast artificial chromosome spanning the 8;21 translocation breakpoint t(8;21)(q22;q22.3) in acute myelogenous leukemia.

The 8;21 translocation is one of the most common specific rearrangements in acute myelogenous leukemia. We have identified markers (D21S65 and a Not I boundary clone, Not-42, referred to as probe B) flanking the chromosome 21 translocation breakpoint (21q22.3) that demonstrate physical linkage in normal genomic DNA, by using at least three restriction endonucleases (Not I, Sac II, and BssHII), and that are located not more than 250-280 kilobases apart. Pulsed-field gel analysis of DNA from somatic cell hybrids containing the 8;21 translocation chromosomes demonstrates rearrangement of these markers. A 470-kilobase yeast artificial chromosome, YAC-Not-42, has been isolated that contains both probes. Mapping of lambda subclones constructed from YAC-Not-42 suggests that greater than 95% (25/26 probes tested) of the yeast artificial chromosome DNA is located on the proximal (D21S65) side of the breakpoint. In situ hybridization studies using metaphase chromosomes from five acute myelogenous leukemia patients with the 8;21 translocation confirmed these results and demonstrated the translocation of probe B to the derivative chromosome 8. A chromosome walk of approximately 39 kilobases from probe B has allowed identification of the breakpoint in DNA from a somatic cell hybrid containing the derivative chromosome 8. Since probe B contains conserved DNA sequences and is in close proximity to the translocation breakpoint, it may represent a portion of the involved gene on chromosome 21.

Blotting, Southern↗
PubMed1991

Mutations in TrpI binding site II that differentially affect activation of the trpBA promoter of Pseudomonas aeruginosa.

In vitro, Pseudomonas aeruginosa TrpI protein activates transcription initiation at the trpBA promoter (trpPB) and represses initiation at its own promoter (trpPI), which diverges from, and overlaps, trpPB. Indoleglycerol phosphate (InGP) reduces the TrpI concentration required for binding to its strong binding site (site I), as measured by repression of trpPI; it also facilitates activation of trpPB, presumably because it enables TrpI to bind to a weaker binding site (site II) and thereby interact with RNA polymerase. The role of site II and InGP in regulation of the two promoters was investigated by constructing site II mutants. A 2 bp substitution affected the ability of TrpI to activate trpPB, but did not significantly affect TrpI binding to site II. A more extensive (8 bp) substitution inhibited TrpI-mediated activation of trpPB and TrpI-mediated protection of site II in a DNase I footprinting assay. However, the mutation did not alter the pattern of TrpI binding observed in gel retardation experiments. In particular, a more slowly-migrating complex (Complex 2) whose appearance was correlated with TrpI binding to site II was formed equally well on a wild-type or substituted DNA fragment. Based on the mutant phenotypes, we propose that a particular sequence of protein--protein and protein--DNA interactions is required for activation of trpPB by TrpI and InGP.

Bacterial Proteins↗
PubMed1991

[Preliminary study on lectin affinity histochemistry for diagnosis and histogenesis of salivary gland carcinoma].

A comparative study was undertaken among mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma and normal salivary glands using lectin affinity histochemical method. It was found that the positive rate was highest in mucoepidermoid carcinoma (P less than 0.05); Among the 4 kinds of lectins used PNA and UEA had different distributions and contents in cancer and control groups (P less than 0.05). The mucoid substances in the cancer tissue were mixed mucin, similar to those in the normal salivary gland. However, there was more mixed mucin in the former than in the latter. This method is useful in diagnosis of salivary gland carcinoma. The relation of glucoprotein content on the cancer cell surface and carcinogenesis is discussed.

Carcinoma↗
PubMed1991

[Screening and identification of monoclonal antibodies against human neutrophil and detection of inhibiting opsonic phagocytic activity].

Using Ficoll-Hypaque gradient centrifugation, we have successfully obtained the neutrophils from normal human donors, which can be used as particle antigens for immunizing BALB/c mice. Hybridomas were produced through the fusion of SP2/0 myeloma cells and splenocytes from immunized BALB/c mice. The ratio of fusion was 1:5. The cells were fused with 30% polyethylene glycol (MW 4000). The rate of fusion was 90%. The antibody producing colonies against the membrane of neutrophils in HAT medium were selected by indirect immunofluorescence assay. Antibody positive rate was 60% (102/170). Limiting dilution was used for colonization of the antibody-producing hybridoma cells. After colonization for three times, one hybridoma cell line was obtained, which could inhibit complement-mediated phagocytosis. Culture supernatant was used against class- and subclass- specific rabbit antisera (rabbit anti-mouse IgM, IgG, IgG1, IgGd22, IgG2b, IgG3) in an agar immunodiffusion system, it was shown to be IgG22.

Animals↗
PubMed1991

[Preliminary studies of notoginsenoside R1-induced differentiation of HL-60 cell lines in vitro].

Our experiments have proved that human promyelocytic leukemia cells (HL-60) could be induced to differentiate in vitro by notoginsenoside R1 into mature neutrophils. The morphological results showed that 68% of HL-60 cells were differentiated in 80 microgram/ml inducer for 5 days, in which metamyelocytes were 32%, banded neutrophils 30% and segmented neutrophils 6% 3H-TdR and 3H-UR incorporate assay showed that notoginsenoside R1 effected synthesis of DNA and RNA while it induced differentiation of HL-60 cell. At 48 h, percent of incorporate inhibition was 26.32% with 3H-TdR and 18.57% with 3H-UR; at 72 h, 17.46% and 21.76%, respectively.

Antineoplastic Agents, Phytogenic↗
PubMed1991

Relationship between invasion and metastasis of tumor cells.

This work was done to examine the relationship between invasion and metastasis of different types of tumor cells. Three kinds of tumor cells were studied: a mouse uterine cervix carcinoma (U14) with high metastatic potential; a human nasopharyngeal carcinoma (CNE-2Z) with high metastatic potential; and a human uterine cervix carcinoma (CC801) with low metastatic potential. CNE-2Z and CC801 were implanted subcutaneously in the footpads and subcapsularly in the testes of nude mice, respectively. U14 was implanted both in the footpads and subcapsularly in the testes of inbred 615-strain mice. With each of these animal models, the extent of tumor invasion could be divided into grades I-IV. The metastasis of tumor cells was found to depend upon: 1) the malignant characteristics of the tumor cells; 2) the degree of local invasion; 3) the presence of tumor cells in the lymphatic ducts and blood vessels; and 4) the organ specificity of metastatic development. Metastasis was most often found when invasion reached a high degree (grades III to IV).

Animals↗
PubMed1991

[The invasive behavior of two human nasopharyngeal carcinoma (NPC) cell lines CNE-1, CNE-2Z in vitro].

Method of co-culture of tumor cells with precultured heart fragments (PHF) in vitro was used in studying the invasive behavior of human nasopharyngeal carcinoma (NPC) cell lines CNE-land CNE-2Z respectively. This improved method was based on the gyrotory shaker organ culture technique originally established by Mareel in order to show NPC cell invasiveness in a rather identical image. Histopathological sections revealed that the tumor cells might invade into the cell layer of fibroblasts surrounding the heart tissue. This would make the heart muscle cells degenerated, atrophied and necrotic and finally displaced by the fibrotic tissue. Data also pointed out that CNE-2Z cells showed more active invasive ability than that of the CNE-1 cells in the organ culture.

Carcinoma, Squamous Cell↗
PubMed1991

[Invasiveness and metastasis of tumor spheroid aggregates of human giant cell carcinoma (lung clone strain PLA801-95D) in vitro and in vivo].

Invasion modols of tumor spheroid aggregates in vitro and in vivo were established by using human giant cell carcinoma (lung strain PLA801-95D). PLA801-95D cells from monolayer cultures were suspended and allowed to form spheroid aggregates for 3 d on a gyratory shaker. In organ culture, PLA801-95D (0.2 mm in diameter) were confronted with 0.4 mm round precultured heart fragments (PHF), then co-cultured on a gyratory shaker. PLA801-95D cells showed a strong capacity of invasion in vitro. In vivo, PLA801-95D spheroids (0.3 mm in diameter) were transplanted subcutaneously into the auricles and flanks of BALB/c nude mice. No s. c. tumor growth was noted in the auricle 4 months after transplantation, but at the s. c. flank, tumors were found in 3 of 5 mice, with invasive growth seen at the site of transplantation. Metastases were found in regional drainage lymph nodes (axillary, submaxillary and inguinal lymph nodes) and in the lungs. PLA801-95D cells had high malignancy in vitro and in vivo. Both spheroid invasion models proved to be suitable for judging the malignancy of human tumor cells and for studying the mechanism of human tumor invasion.

Animals↗
PubMed1991

Regional differences in N-nitrosamine content of traditional Chinese foods.

Traditional uncooked and cooked Chinese foods from six provinces with different cancer patterns were analysed for volatile N-nitrosamines (VNA) by gas chromatography-thermal energy analysis. Selected samples were also analysed for N-nitrosamino acids (NAA). N-Nitrosodiethylamine was the VNA found most often (in 91/108 samples; less than 0.2-17.5 micrograms/kg), followed by N-nitrosodimethylamine (in 75/108 samples; less than 0.2-17.3 micrograms/kg). N-Nitrosodipropylamine was detected in 11/108 samples (0.9-6.2 micrograms/g). Samples selected for analysis of NAA on the basis of their VNA content contained one or more NAA, including N-nitrosoproline and N-nitrosothiazolidine 4-carboxylic acid (range, 1.1-115 micrograms/kg; average, 35 micrograms/kg). Both the incidence and pattern of occurrence of VNA suggest that Chinese foods differ from western foods, which would not be expected to contain NAA as frequently nor to contain N-nitrosodipropylamine. The highest percentages of positive samples were from Zhejiang and Fujian provinces (89 and 91%, respectively), and they had the highest average VNA content. Beijing city and Sichuan province gave the lowest percentages of positive samples (75 and 56%, respectively) and the lowest average VNA content.

China↗
PubMed1991

Clinical and experimental observations on treatment of peptic ulcer with wei yang an (easing peptic-ulcer) capsule.

The therapeutic effects of peptic ulcer treated with cimetidine and Wei Yang An were compared clinically and experimentally by the double blind method. Results showed that the effects of the two are similar, but the long-term effect of Wei Yang An was better. Wei Yang An was also good for most cimetidine resistant ulcers, with few side effect. Animal experiment showed that Wei Yang An inhibited the ulcers.

Adult↗
PubMed1991

[Anti-tumor effect of Cetraria laevigata Rassad. polysaccharides].

The anti-tumor effect of Cetraria laevigata polysaccharides has been investigated in mice using sarcoma 180; Ehrlich ascitic tumor, cervical carcinoma u-14 and leukemia L7217. The results show that Cetraria laevigata polysaccharides may inhibit the growth of sarcoma 180, Ehrlich ascitic tumor and cervical carcinoma u-14 in mice at a dose of 200mg/kg ip (1/5 LD50). However, the survival time of leukemia L7217 wasn't prolonged. The reticuloendothelial system phagocytic function in mice was increased at ip doses of 50 mg/kg and 100 mg/kg (1/10 and 1/20 LD50).

Animals↗
PubMed1990

Comparison of the clinical performance, contraceptive efficacy and acceptability of levonorgestrel-releasing IUD and Norplant-2 implants in China.

The levonorgestrel-releasing IUD (LNG-IUD, 20 micrograms/d) and the Norplant-2 implants were studied in a randomized comparative clinical trial with 200 women for one year. No pregnancy or expulsion occurred with the Norplant-2. In the LNG-IUD group, there was one pregnancy at the 12th month of use after an unnoticed expulsion. The net cumulative pregnancy and expulsion rates of LNG-IUD were 1.0 and 3.0. The removal rate due to menstrual disturbances in both LNG-IUD and Norplant-2 groups was 3.0. The use-related discontinuation rates were 9.0 and 3.0, and the continuation rates were 90.0 and 96.0, respectively. The differences were not statistically significant. Menstrual disturbance was the main side effect. It was improved after long time use, especially in the LNG-IUD group. After one year, the percentages of women with amenorrhea were 18.9 for the LNG-IUD and 8.3 for the Norplant-2. The menstrual blood loss was statistically significantly reduced in the LNG-IUD group, and blood haemoglobin concentration increased in both groups. The LNG-IUD and Norplant-2 are highly effective, safe, long-acting, and well accepted by the Chinese women.

Administration, Intravaginal↗
PubMed1990

Free energy of sickling: A simulation analysis.

Molecular dynamics simulations were performed to calculate the difference between the dimerization free energies of normal human deoxyhemoglobin (HbA) and the mutant sickle-cell deoxyhemoglobin HbS (Glu-beta 6----Val) for one of the lateral contacts in the HbS x-ray structure. The simulations yield a value of--15 kcal/mol. Although there is no quantitative experimental value for comparison, this is in qualitative agreement with the experimental result that HbS self-assembles into multistranded fibers that are responsible for erythrocyte sickling, while HbA does not. The free-energy difference was decomposed into enthalpic and entropic terms, both of which are significant, and the contributions of individual protein residues and of the solvent were examined. Electrostatic effects play the dominant role in favoring dimerization of HbS compared with HbA; van der Waals interactions make a negligible contribution to the difference. Both differential solvation and protein-protein interactions are important. Interactions within the donor tetramer (i.e., that containing the Glu-beta 6 mutation site), as well as those with the acceptor tetramer, contribute to the preferential free energy of dimerization of HbS.

Calorimetry↗
PubMed1990

Acetylcholine reverses effects of beta-agonists on pacemaker current in canine cardiac Purkinje fibers but has no direct action. A difference between primary and secondary pacemakers.

We have investigated the actions of acetylcholine in the absence and presence of the beta-agonist isoproterenol in cardiac Purkinje fibers. beta-Agonists, like isoproterenol, increase the magnitude of the pacemaker current (If) in cardiac myocytes by shifting its activation voltage more positive on the voltage axis. We find that acetylcholine has no effect on If in the absence of isoproterenol. However, if If is first increased by beta-agonist stimulation, acetylcholine can then return If to control levels. This effect on If is exerted through muscarinic receptors since atropine prevents this action of acetylcholine. Functionally, this action of acetylcholine can guarantee the maintenance of ventricular pacemakers when there is high parasympathetic tone but can also prevent extra ventricular beats when sympathetic and parasympathetic tone are both high.

Acetylcholine↗
PubMed1990

[Short-term curative effect of cultured Cordyceps sinensis (Berk.) Sacc. Mycelia in chronic hepatitis B].

33 cases of chronic hepatitis B. patients treated with cultured Cordyceps sinensis mycelia have shown that the drug improves the liver function, promotes negative transfer HBsAg, and markedly helps to raise plasma albumin, resist high gamma globulin and to adjust body immunocompetence. It is therefore suggested that cultured Cordyceps sinensis mycelia may be used as a medicine for chronic hepatitis B. patients in adjusting protein metabolism and correcting inversion of albumin and globulin.

Albumins↗
PubMed1990

The role of substance P of the central nervous system in the pathogenesis of spontaneously hypertensive rats.

In comparing the involvement of substance P (SP) in the central regulation of vasomotor tone in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR), we found that: the degree of SP-like immunoreactivity (SPLI) in the hypothalamus, rostral ventral surface of the medulla oblongata (RVM) and intermediolateral cell column (IML) of the thoracic spinal cord of SHR rats was significantly higher than in WKY rats; intrathecal injection (ith) of SP receptor antagonist D-Pro2, D-Phe7, D-Trp9-SP (D-SP) caused a decrease of mean blood pressure (MBP) in both SHR and WKY rats. These results indicate that SP might participate in the pathogenesis of hypertension and the regulation of normal blood pressure.

Animals↗