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J Gao

Publications and source records attributed to J Gao.

At least 433 records · Page 24Linked to original sources
PubMed1994

[The reversing effect of 4-hydroxycarbophenyl retiamide (R II) on the malignant phenotype of mouse forestomach carcinoma (MFC) cell line and the mechanism of its action].

4-hydroxycarbophenyl retiamide (R II) is a new synthetic analogue of retinol, but with lower toxicity than retinoic acid. We studied its induction effects and its effects on some malignant phenotypes of the MFC cell line. The mechanism of these effects was also explored. MFC cells were grown in complete RPMI 1640 medium supplemented with 10(-5) mol/L R II for five passages. By then the cell growth rate slowed down; the rate of 3H-TdR incorporation and the colony-forming capacity of MFC cells decreased; morphologically, the cells became epithelial rather than fibroblastic with various degrees of polarization. Further investigation about the mechanism of these changes was also undergone. First by flow cytometry, it was shown that the R II-treated cells were retained in G1 phase. Second, dot blot hybridization showed a decrease of more than 61% of c-myc mRNA and an increase of more than 52% of v-fos mRNA. The major chromosome distribution changed from 54-56 to 46-54 with an increase in diploid. Scanning microscopic examination showed that the R II-treated cells were covered by numerous microvilli and pseudopodia with round terminal expansion in contrast to the ruffle protrusions and leaf-like pseudopodia of control cells. All the results suggested that R II could reverse some malignant phenotypes of MFC cells.

Animals↗
PubMed1994

A study of histology and enzymatic histochemistry on rabbit's retina in acute ocular hypertension.

The changes of activities of enzymes relating to energy metabolism in rabbit's retina in acute ocular hypertension were observed. The activities of succinate dehydrogenase and adenosine triphosphatase were found to be reduced, while the activities of the lactatic dehydrogenase and glucose-6-phosphatase increased. The results revealed the metabolic disturbance of energy in retina after acute ocular hypertension might be the underlying factors relating to the defects of the functions and structures of the retina.

Adenosine Triphosphate↗
PubMed1994

The mitochondrial DNA mutation at position 11778 in Chinese families with Leber's hereditary optic neuropathy.

We amplified the 340 bp of mitochondrial DNA (mtDNA) by PCR including the recognized sequence of restriction enzyme of SfaN I. After amplification and digestion of SfaN I, two bands of 190 bp and 150 bp appeared in the mtDNA of four normal individuals but only one band of 340 bp appeared in the mtDNA with the mutation of G to A at the site of the nucleotide 11778 because such mutation destroyed the recognized sequence of SfaN I. We studied the mtDNAs of the patients with Leber's hereditary optic neuropathy from 19 Chinese families and their maternal relatives as well as the normal individuals i. e. the husbands of the female members of the pedigrees. The results show that 66.7% of the patients (30/45) and 54.7% of the maternal relatives (29/53) have such a mutation, while no such a mutation exists in the four normal individuals. So, we conclude that the mutation of mitochondrial DNA at position 11,778 is also a major cause of LHON in China.

Asian People↗
PubMed1994

[Study on the invasive properties of cloned human nasopharyngeal carcinoma CNE2Z variants using organ culture in vitro].

Using limiting dilution assay, variants were cloned from the CNE-2Z cell line. The variants CNE2L2, CNE2H2, CNE2L4 and CNE2M2, with cell electrophoresis rates which differed greatly, were assayed for their invasive capabilities by observing their ability to invade preculture embryonic chicken heart fragment (PHF) in organ culture using a gyrotory shaker system. The results indicated that CNE2L2 variant cells invaded 9-day-old chicken embryonic heart fragments at a rate significantly higher than those seen using CNE2L4 and CNE2M2 in 7-day assay. Computer image analysis showed that the CNE2L2 cells occupied 80.2% of the PHF area much greater than that occupied by CNE2L4 (46.5%) or CNE2M2 (36.5%). This experiment also showed that the electrophoresis rate of the CNE2Z variants was positively related to their invasive capabilities in vitro.

Animals↗
PubMed1994

[Studies on the gap junctional intercellular communication of human nasopharyngeal carcinoma cells and effect of RII].

To evaluate the effects of gap junctional intercellular communication (GJIC) on the growth, invasion and metastasis of tumor, human nasopharyngeal carcinoma (HNPC) parent cell line (CNE-2Z) and its variants (L2, H2, L4) with different invasive and metastatic potential were examined in vitro. Only a few intermediate junction (IJ) but no gap junction (GJ) structures were observed under EM. The parent line cells showed marked GJIC, while its variants lacked this function by SLDT technique. It was further shown that L2 cell line (variant with high invasive potential) had lower concentration of cytosolic free calcium ([Ca2+]i) compared to H2, L4 cell lines (variants with medium and low invasive potential, respectively). It reflected that some correlation may exist between [Ca2+]i level and the invasive potential of HNPC cell lines. The effect of RII on GJIC of HNPC was also investigated. After 3-7 ds of RII (0.0001 mol/L) treatment, there was no change in the number of GJs. The GJIC function of CNE-2Z weakened and then disappeared finally with prolonged RII treatment. The level of [Ca2+]i in HNPC cells apparently fell after 6h of RII treatment, and rose to original level with persistent RII treatment. Whether the fluctuating of [Ca2+]i level relates the inhibitory effect of RII treatment. Treatment on the growth and invasion needs to be further studied.

Calcium↗
PubMed1994

Effects of kappa, sigma, and phencyclidine receptors agonists in rat tail arteries of spontaneously hypertensive rats.

The effects of the kappa receptor agonist trans-4-dichloro-N-methyl-N-(2-(1-pyrrolidin)cyclohexyl)-benzen eacefamide methane sulfonate (U-50 488H), etorphine, the sigma (sigma) receptor agonists (+)-3-(3-hydroxychenyl)-N-(1-propyl) piperidine ((+)-3-PPP), 1, 3-di-o-tolyl-guanidine (DTG), and the phencyclidine (Phe) receptor agonists Phe, N-(1-(2-thienyl)cyclohexyl) piperidine (TCP), and dizocilipine maleate (MK-801) on electrically stimulated constriction (ESC) were investigated in the rat tail arteries (RTA) of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Etorphine and U-50 488H inhibited the response to ESC in SHR more than that in WKY. The effects of U-50 488H were greater than those of etorphine. The IC50 and Kact of U-50 488H in SHR were 2.5 +/- 2.0 and 0.43 +/- 0.22 mumol.L-1, respectively, while the corresponding figures in WKY were 23 +/- 15 and 2.3 +/- 1.0 mumol.L-1, respectively (P < 0.05). The inhibitory effects of (+)-3-PPP on ESC in RTA of SHR were weaker than those in WKY. Its IC50 and Kact in SHR were 11.6 +/- 5.4 and 0.87 +/- 0.30 mumol.L-1, respectively, while the corresponding figures in WKY were 0.63 +/- 0.16 and 0.35 +/- 0.18 mumol.L-1, respectively (P < 0.05). But the inhibitory effect of DTG was very slight and the difference of Kact between WKY and SHR was not significant. The enhancing effects of Phe, TCP, and MK-801 in SHR were not at all different from those in WKY at each concentration tested.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1994

[Enhancing effects of Herpesvirus hominis on sodium glutamate neurotoxicity].

The neurotoxic effects of sodium glutamate (MSG, 2.5 g.kg-1 sc) and the enhancing effects of neurotropic Herpesvirus hominis (HVH, 0.2 ml/mouse ip) on MSG toxicity were studied through histomorphological observations, together with detection of the concentration of both mitochondrial protein bound Ca2+ and intracellular free Ca2+ ([Ca2+]i) by the Tb3+ fluorescent probe and Ca2+ indicator Fura-2/AM, respectively. It was found that in 10-d-old mice the neurons in arcuate hypothalamic nucleus degenerated severely after treatment with HVH+MSG, showing swollen edematous cytoplasm, dark pyknotic nuclei as well as a decrease in the amount of the neurons. The hypothalamic and spinal cord mitochondrial Tb3+ relative fluorescent intensity increased from 20 +/- 3 and 20 +/- 1 to 28 +/- 5 and 34 +/- 6, ie, the mitochondrial protein bound Ca2+ reduced significantly. MSG elevated the [Ca2+]i levels from 0.11 +/- 0.03 to 0.69 +/- 0.19 mumol.L-1 by not only stimulating the Ca2+ influx but also releasing the Ca2+ from intracellular stores. These findings suggested that MSG neurotoxicity was probably related to the overloading of neuroplasmic Ca2+, the destruction of neuronal abilities to deplete or sequester the intracellular Ca2+, as well as the irreversible neuronal injury and death.

Animals↗
PubMed1994

[The relationship between the major components of extracellular matrix and growth, motility and invasion in mice pulmonary adenocarcinoma].

After mouse pulmonary adenocarcinoma cell line LA795 was implanted in the subrenal capsule of T739 mice, the local distribution of fibronectin (FN), laminin (LN) and type IV collagen was detected by indirect immunoperoxidase and immunofluorescence staining and were observed during tumor growth at different time intervals. As the tumors progressed, it was shown that the expression of FN decreased while that of LN and type IV collagen gradually increased, their distribution patterns were also different. LN and type IV collagen were absent in the basement membrane in the tumor invasion areas. In order to verify the in vivo observations, various in vitro methods were used. We found expression of FN and LN but no expression of type IV collagen mRNA in LA795 cell line. Assay of random migration of tumor cells was employed to check the influence of FN, LN or type IV collagen on the motility of tumor cells. It was demonstrated that LN, FN, type IV collagen and in particular, LN could promote the motility of tumor cells individually. Cultured with addition of LN or FN, tumor cell colonies expanded diametrically more rapidly. The results indicated that FN, LN and type IV collagen may contribute to tumor invasion and metastasis.

Adenocarcinoma↗
PubMed1994

[Transplacental neurotoxic effects of monosodium glutamate on structures and functions of specific brain areas of filial mice].

Monosodium glutamate (MSG) was shown to penetrate placental barrier and distribute almost evenly among embryonic tissues using 3H-Glu as a tracer. When a lower (1.0 mg/g) and a higher (2.5 mg/g) doses of MSG were alternatively injected to Kunming maternal mice in every other days from mating to deliveries, obvious injury occurred in the ability of memory retention and Y-maze discrimination learning of adult filial mice pregnantly treated with higher doses (2.5 mg/g) of MSG. Meanwhile, the neuronal damages were observed in not only arcuate nucleus but also ventromedial nucleus of hypothalamus. Characteristic cytopathological changes induced by MSG showed swollen cytoplasm, dark pyknotic nuclei and loss of neurons. The radioligand-bindings in both hippocampus and hypothalamus altered significantly after the pregnant treatment of MSG. Possible mechanisms underlying MSG excitotoxic phenomena studied in single neuron by use of Ca2+ sensitive indicator Fura-2 with Spex AR-CM-MIC Cation Measurement System, might be due to increases of intracellular free Ca2+ concentration induced by MSG exposure, which was related to both the influx of Ca2+ and the depletion of Ca2+ from the intracellular Ca2+ stores. These experimental findings indicated that MSG performed its transplacental neurotoxicity in a dose-dependent manner. The excessive activation of Glu receptors and the overloading of intracellular Ca2+ induced by MSG ultimately leading to neuronal death may result in the reduction of the capability of learning and memory in adult filial mice pregnantly treated with MSG.

Animals↗
PubMed1994

Dynamic changes of fibrinopeptides A and B in sera of burn patients and their effects on vascular endothelial cells.

In this study, dynamic changes of fibrinopeptides A and B (FPA, FPB) in sera of burns patients are determined with an HPLC method. On this basis detrimental effects of FPA and FPB on vascular endothelial cells (VEC) are observed in vitro. The main results are as follows: (1) FPA and FPB in 18 burn patients' sera increase at day 2 postburn, reach peaks at days 5-7 postburn, then decline after day 15 postburn, and return to the control levels at day 25 postburn. The fluctuations in FPA and FPB levels in burn patients' sera are parallel to the progress of burn illness. The measurements of FPA and FPB levels in burn patients' sera may be useful in evaluating patients' condition. (2) FPA and FPB are detrimental to the cultured VEC in vitro. Characteristics of their injurious effects are: specific, irreversible and dose dependent. FPA and FPB may play an important role in endothelial injury.

Adolescent↗
PubMed1993

Evidence from transgenic mice that glucose transport is rate-limiting for glycogen deposition and glycolysis in skeletal muscle.

A line of transgenic mice was constructed in which the human Glut1 glucose transporter is overexpressed in skeletal muscle. Overexpression of Glut1 protein was evident in epitrochlearis, extensor digitorum longus (EDL), and quadriceps muscles, and resulted in 6.6-7.4-fold elevations in basal glucose transport activity as measured in isolated muscles in vitro. The elevated glucose transporter activity in the skeletal muscles of transgenic mice was associated with a 10-fold increase in glycogen concentration in EDL and quadriceps muscles that was not due to an increase in muscle glycogen synthase activity or a decrease in glycogen phosphorylase activity. The increased glucose transport activity also resulted in a 2-fold increase in muscle lactate concentration, with no increase in muscle glucose 6-phosphate. Despite a slight (10%) increase in muscle hexokinase activity, there was a 4-fold increase in total muscle free glucose in transgenic mice, indicating that hexokinase becomes rate-limiting for glucose uptake when the rate of glucose transport is very high. These results demonstrate that the muscle glycogen content can be dramatically elevated by increasing the muscle Glut1 protein level and that glucose transport is a rate-limiting step for muscle glucose disposal in normal, resting mice.

Animals↗
PubMed1993

Detection of DNA rearrangements in the AML1 and ETO loci and of an AML1/ETO fusion mRNA in patients with t(8;21) acute myeloid leukemia.

The (8;21)(q22;q22) translocation is a frequent karyotypic abnormality seen in approximately 40% of patients with acute myeloid leukemia subtype M2 (AML-M2) and an abnormal karyotype. The translocation interrupts two genes, AML1 on chromosome 21 and ETO on chromosome 8, that are consequently fused in the der(8) chromosome to produce a novel chimeric gene and message. Selected genomic DNA probes from chromosome 21 and from chromosome 8 near the breakpoint junction detect rearrangements in the DNA of about 80% of the patients with the rearrangement at diagnosis and in relapse. We analyzed the DNA of 20 patients with t(8;21) AML by standard Southern blot with probes originating from chromosomes 21 and 8 near the breakpoint junction, and we identified rearranged bands in 17 of the 20 patients at diagnosis and in relapse. We also used the polymerase chain reaction (PCR) with appropriate primers from the AML1 and ETO genes to amplify the cDNAs from a cell line with the t(8;21) and from seven AML patients with the t(8;21). We detected a fused transcript in the cell line and in all of the patients analyzed, including three patients who did not show any rearrangement by Southern blot analysis and one patient in hematologic remission, who later relapsed. Combining the results from Southern blot and PCR analysis, we could detect the t(8;21) in all of the patients tested. These results indicate that, whereas several DNA probes used as genetic markers do detect the t(8;21) in most, but not all Southern blots of patients with AML, PCR amplification with primers from AML1 and ETO can be used as a more sensitive and accurate means for detecting this chromosomal abnormality, and for observing the patients' response to therapy.

Adult↗
PubMed1993

Nucleotide sequences of the trpI, trpB, and trpA genes of Pseudomonas syringae: positive control unique to fluorescent pseudomonads.

A 904-bp probe from Pseudomonas aeruginosa was used to identify the trpB, trpA and trpI genes of Pseudomonas syringae. Transcription initiation at the P. syringae trpBA promoter in vitro was activated by the P. aeruginosa TrpI protein in the presence of indoleglycerol phosphate. Thus, trpB and trpA are regulated positively in three species of fluorescent pseudomonads, P. aeruginosa, P. putida, and P. syringae, but in no other eubacteria so far investigated [Crawford, Annu. Rev. Microbiol. 43 (1989) 567-600]. In addition to conservation of protein-coding sequences, there is a high degree of nucleotide sequence identity in the intergenic control region that includes the divergent trpI and trpBA promoters, especially in the binding sites for TrpI protein. Differences in patterns of codon usage distinguish the trpI genes of P. syringae and P. putida from P. aeruginosa trpI and from the trpB and trpA genes of all three species.

Amino Acid Sequence↗
PubMed1993

High-titre antibodies to a foreign epitope elicited by affinity-purified hybrid LamB proteins.

A monoclonal antibody to the LamB protein, named LBS-1, was developed and characterized. It was then covalently bound to Sepharose and used to purify hybrid LamB proteins from Escherichia coli crude extracts. A peptide of the interferon-gamma (IFN-gamma) NH2-terminal region, inserted within the LamB protein, was used as a model to assess immune response in mice injected with sonicated E. coli extract or with affinity-purified hybrid LamB protein. None of the mice immunized with the whole bacterial extract produced antibodies to IFN-gamma. On the other hand, all the mice immunized with the purified protein developed high-titre anti-IFN-gamma antibodies. These results might be due to the presence of bacterial components capable of masking the LamB protein to the immune system. The use of affinity-purified LamB proteins may constitute in some instances a more effective way of generating an immune response against foreign epitopes as opposed to whole bacterial antigens.

Amino Acid Sequence↗
PubMed1993

Influence of gender and the endocrine environment on the distribution of androgen receptors in the lacrimal gland.

Androgens are known to regulate both the structure and function of lacrimal tissue in a variety of species. To explore the endocrine basis for this hormone action, the following study was designed to: (1) determine the cellular distribution of androgen receptors in the lacrimal gland; and (2) examine the influence of gender and the endocrine environment on the glandular content of these binding sites. Lacrimal glands were obtained from intact, castrated, hypophysectomized, diabetic or sham-operated male or female adult rats, mice or hamsters, as well as from orchiectomized rats exposed to placebo compounds or physiological levels of testosterone. The cellular location of androgen receptors was evaluated by utilizing an immunoperoxidase protocol, in which a purified rabbit polyclonal antibody to the rat androgen receptor was used as the first antibody. Our findings with lacrimal glands showed that: (1) androgen receptors are located almost exclusively in nuclei of epithelial cells; (2) the cellular distribution or intranuclear density of these binding sites is far more extensive in glands of males, as compared to females; (3) orchiectomy or hypophysectomy, but not sham-surgery or diabetes, lead to a dramatic reduction in the immunocytochemical expression of androgen receptors; and (4) testosterone administration to orchiectomized rats induces a marked increase in androgen receptor content, relative to that in placebo-exposed glands. Our results also reveal that a 10 kb androgen receptor mRNA exists in the rat lacrimal gland. Overall, these findings demonstrate that gender and the endocrine system may significantly influence the distribution of androgen binding sites in rat lacrimal tissue. Moreover, our results show that androgens up-regulate their own lacrimal gland receptors.

Animals↗
PubMed1993

The nature of cation-pi binding: interactions between tetramethylammonium ion and benzene in aqueous solution.

A combined quantum mechanical and molecular mechanical Monte Carlo simulation method was used to determine the free energy of binding between tetramethylammonium ion (TMA+) and benzene in water. The computed free energy as a function of distance (the potential of mean force) has two minima that represent contact and solvent-separated complexes. These species are separated by a broad barrier of about 3 kJ/mol. The results are in good accord with experimental data and suggest that TMA+ binds to benzene more favorably than to chloride ion, with an association constant of about 0.8 M-1.

Benzene↗
PubMed1993

Dietary fibers and fats alter rat colon protein kinase C activity: correlation to cell proliferation.

Protein kinase C activity and cell proliferation in rat proximal colonic mucosa were determined following diet modification with select fibers and fats for 3 wk. Rats were assigned to one of nine dietary groups: three fibers (cellulose or pectin at 6 g/100 g diet or fiber free) x three fats (beef tallow, corn oil, fish oil at 15 g/100 g diet). Protein kinase C activity was determined by measuring the phosphorylation of a highly selective synthetic peptide derived from myelin basic protein. In vivo cell proliferation was measured by bromodeoxyuridine incorporation into DNA. There was a significant main effect of fat (P = 0.0008) but not fiber (P = 0.375) on the ratio of membrane to cytosolic protein kinase C with diets containing fish oils resulting in the highest ratios, corn oils in the lowest ratios and beef tallow producing an intermediate ratio. There was an interactive effect of fat and fiber on the proliferative zone (P = 0.04). Pectin resulted in a significantly greater proliferative zone than did cellulose and the fiber-free diet but only when the fat source was corn oil. There was a positive correlation between proliferative zone and both membrane protein kinase C activity (r = 0.76, P = 0.02) and protein kinase C membrane:cytosol ratio (r = 0.64, P = 0.06). Although the positive relationship between proliferative zone and protein kinase C activity has been reported previously, the high membrane protein kinase C activity found with fish oil supplementation compared to the low activity found with corn oil supplementation was unexpected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗