Biomedical subjects

X Guan

Publications and source records attributed to X Guan.

At least 91 records · Page 5Linked to original sources

PubMed1996

[The influence of electroacupuncture on the mast cells in the acupoints of the stomach meridian].

Giving electroacupuncture at unilateral "Biguan" and "Zusanli" points, we observed the rat subcutaneous mast cells of "Tianshu", "Biguan", "Futu", "Zusanli" and "Xiajuxu" acupoints in bilateral Stamach Meridian. It was found that the numbers of mast cells in all the acupoints studied were higher than that in the non acupoint area. The numbers of mast cell in acupoints were increased under electroacupuncture, while that in non acupoint area was not changed. The results suggested the mast cells play an important role in the functions of the Meridian.

Acupuncture Points↗

PubMed1996

[Influence of electroacupuncture and capsaicin treatment on AChE activity and [3H]-QNB binding sites in the spinal dorsal horn].

1.5% Capsaicin (Cap) or Vehicle was respectively used to treat the right or left sciatic nerve in 20 Sprague-Dawley rats. On the seventh day, the 20 rats were at random divided into electroacupuncture (EA) group and non-EA group, the spinal cord corresponding to the afferent segments of sciatic nerve was taken out for observing the changes of acetylcholinesterase (AChE) activity and [3H]-quinuelidinylbenzylate (QNB) binding sites in the spinal dorsal horn (SDH). The results were as follows: (1) EA "Huantiao" could enhance AChE activity in the SDH and decrease [3H]-QNB binding sites; (2) Cap treating sciatice nerve could weaken AChE activity in the SDH and merease [3H]-QNB binding sites; (3) Cap treatment could inhibit or partially inhibit the actions of EA as above. The results indicated that ACh participated in the primary afferent of acupuncture information and might exist in Cap-sensitive neurons.

Acetylcholinesterase↗

PubMed1996

[Segmental influence of dorsal root action potentials evoked by stimulating the acupoints after acupuncture along meridians].

Using the method of recording the corresponding dorsal root action potentials evoked by stimulating the acupoints, we found that electro-acupuncture could not only expand the segmental of potentials, but also amplitude the potentials. The results proved the acupuncture sensation may be transsegmental afferent after acupuncture along the meridians. This study gave a new evidence for the mechanism's explanation of propagated sensation along the meridians.

Acupuncture Points↗

PubMed1996

[The selection of highly lung metastatic salivary adenoid cystic carcinoma clone].

After 5 times repeated selection in vivo, combined with cloning technique in vitro and analysing of platelet aggregation activity, we had selected a highly lung metastatic salivary adenoid cystic carcinoma clone M-5clone24 (Acc-M). Compared with Acc-2, its metastatic rate was 96% vs. 18%; the weight of metastatic lung was 0.88 g vs. 0.31 g. The metastatic rate and the weight of metastatic lung positively correlated with platelet aggregation activity. The aggregation activity might be used as a useful parameter to assess Acc metastasis potential.

Animals↗

PubMed1996

[The relationship of C fiber to 5-hydroxytryptamine in spinal cord of rat in electroacupuncture analgesia].

By using spectrofluorophotometry, it was observed that electroacupuntrure at "Huantiao" points of rat could decease the content of 5-hydroxytryptamine (5-HT) and increase the content of 5-hydroxyindoleacetic acid (5-HIAA) in spinal cord. However, the above effects of electroacupunture were obviously reduced after the C fibers of rats had been destroyed by capsaicin, which suggesting that capsaicin-sensitive C fiber might take part in the roles of electroacupuncture's promoting the release and utilization of 5-HT in spinal cord.

Acupuncture Analgesia↗

PubMed1996

[Electroacupuncture along meridians activating subcutaneous primary afferents in acupoints--CB-HRP tracing study].

The experiment was performed to observe the segmental distribution of sensory afferent nerves in acupoints and the influence of electroacupuncture (EA) along meridians on it. 1% CB-HRP solution (5 microliters) was injected subcutaneously at unilateral "Zusanli" or "Ruzhong" acupoint of rats. The HRP labeled cells were counted in the related spinal dorsal root ganglia (DRG). The results were as follows: the sensory nerve terminals of "Zusanli" acupoint mainly projected to the neurons of L4 and L5 DRG and that of "Ruzhong" acupoint projected to the neurons of T4, T5 and T6 DRG; sensory nerve terminals of "Zusanli" or "Ruzhong" acupoint were activated by the EA stimulation along meridians, their ability of uptaking HRP was enhanced, so the HRP labeled cells increased in the related DRG, the HRP labeled DRG segments spread. This study provides a new morphological evidence for the mechanism's explanation of propagated sensation along the meridians.

Acupuncture Points↗

PubMed1995

Isolation of YAC insert sequences by representational difference analysis.

We present a method for the isolation of YAC insert sequences by representational difference analysis (RDA). To achieve maximal representation of the sequences, the amplicons were generated from a Mbol digestion product. RDA was performed using a 970 kb insert YAC clone. After two rounds of re-association and selective amplification 92% of the difference product represented sequences derived from the YAC insert. Twenty insert-specific sequence-tagged sites were readily defined. The difference product was also successfully used to isolate microsatellite markers, to identify clones from a human PAC library and as a chromosome painting probe in fluorescence in situ hybridization.

Base Sequence↗

PubMed1995

An integrated high-resolution physical map of the DPC/BRCA2 region at chromosome 13q12.

We identified a homozygous deletion in a pancreatic carcinoma (DPC) that localized to a 1-cM region at chromosome 13q12.3, which lay within the 6-cM locus of familial breast cancer susceptibility (BRCA-2). Here we present a physical map of the region, consisting of YAC, PAC, and cosmid contigs. The YAC contig comprises 16 clones that together span the entire BRCA2 region. The PAC contig comprises 22 clones that together span the DPC region. Seventy cosmid clones were localized within and near the DPC region. Thirty-five sequence-tagged sites were defined and localized within the map. The map indicates the size of the DPC region to be near 250 kb, and provides mapped and cloned resources for the search for the putative tumor suppressor gene(s) in the region.

Base Sequence↗

PubMed1995

Inhibition of gap junctional intercellular communication and enhancement of growth in BALB/c 3T3 cells treated with connexin43 antisense oligonucleotides.

Many studies have correlated reductions in gap junctional intercellular communication (GJIC) with altered cellular growth, tumor promotion, and neoplastic transformation. To test directly whether reduced GJIC affects cellular growth, GJIC was inhibited in murine BALB/c 3T3 fibroblasts by treatment with a phosphorothioate-modified antisense oligonucleotide targeted against the connexin43 translation start codon, and in vitro cell growth was monitored. The cells were incubated with the oligonucleotide (0.1-0.5 microM) in liposomes in serumless culture medium for 16 h; washed and refed with serum-containing medium; and analyzed for dye-coupling, connexin43 protein and mRNA levels, and cell growth over the next 5 d. The antisense oligonucleotide inhibited dye-coupling and reduced connexin43 protein levels in a concentration-dependent manner but had no effect on connexin43 mRNA levels. Cell growth rate was not affected, but saturation density was increased approximately threefold by the oligonucleotide. These data support a role for GJIC in the establishment of contact inhibition of in vitro cell growth.

3T3 Cells↗

PubMed1995

Changes in gap junction permeability, gap junction number, and connexin43 expression in lindane-treated rat liver epithelial cells.

The pesticide lindane (gamma-hexachlorocyclohexane) is a mammalian neurotoxin and hepatocarcinogen. Lindane can inhibit gap junctional intercellular communication (GJIC) and this effect may contribute to its toxic properties. The mechanism of inhibition of GJIC by lindane in WB-F344 rat liver epithelial cells was studied to determine if altered gap junction permeability, gap junction number, and/or gap junction protein (connexin43) expression were involved. GJIC was monitored by fluorescent Lucifer Yellow CH dye microinjection (dye-coupling). Gap junction number was quantified visually after indirect immunostaining of gap junctions using an anti-connexin43 monoclonal antibody. Connexin43 mRNA and protein levels were determined by Northern and Western blotting, respectively. Short-term treatment (10-30 min) with lindane (50 microM) resulted in the rapid (within 10 min), nearly complete loss of dye-coupling but no changes in gap junction number of connexin43 mRNA or protein levels. Medium-term treatment (1-4 hr) resulted in the loss of dye-coupling, gap junctions, and phosphorylated connexin43 proteins. Long-term treatment (1-14 days) led to reductions in dye-coupling, total connexin43 protein, and connexin43 mRNA. Nuclear run-on assays indicated that transcription of the connexin43 gene was reduced nonspecifically by lindane. These data indicate that reductions in gap junction permeability, number, and expression may be involved in the inhibition of GJIC depending on pesticide treatment duration.

Animals↗

PubMed1995

Down-regulation by butylated hydroxytoluene of the number and function of gap junctions in epithelial cell lines derived from mouse lung and rat liver.

The mouse pneumotoxicant and lung and liver tumor promoter butylated hydroxytoluene (BHT) was examined for its effects on gap junctional intercellular communication (GJIC) in mouse lung epithelial (C10) and rat liver epithelial (WB-F344) cell lines. GJIC, as measured by fluorescent dye microinjection, was inhibited in both types of cells by BHT in dose- and time-dependent fashions. Inhibition was detected in WB-F344 cells at BHT concentrations > or = 62.5 microM and in C10 cells at concentrations > or = 150 microM after 4 h treatment. Inhibition occurred within 15-30 min and was reversed by removing BHT from the culture medium. The highly toxic BHT metabolite 6-t-butyl-2-(hydroxy-t-butyl)-4-methylphenol (BHTOH) and the non-toxic BHT metabolite, 2,6-di-t-butyl-4-hydroxymethylphenol (BHTBzOH) were also tested. In both cell lines BHTOH was a more potent inhibitor of GJIC than BHT, whereas BHTBzOH was ineffective. The mechanisms of inhibition of GJIC by BHT were also examined. The initial rapid inhibition detected within 15-30 min may have been due to gap junction channel closure or blockage, since no changes in gap junction number, connexin (Cx) 43 levels or Cx43 phosphorylation were observed. By 2-4 h, however, gap junctions were internalized into the cytoplasm, the number of immunodetectable plasma membrane gap junctions was reduced and phosphorylated Cx43-P2 was decreased. Treatment of the cells for 24 h with 12-O-tetradecanoylphorbol-13-acetate (TPA) prevented inhibition of GJIC by TPA, but not by BHT. Western blot analyses of TPA-treated WB-F344 or C10 cells revealed the presence of a hyperphosphorylated form of Cx43 (Cx43-P3) and no reduction in Cx43-P2, in contrast to BHT-treated cells. These data suggest that BHT and TPA inhibit lung and liver epithelial cell GJIC through distinct mechanisms.

Animals↗

PubMed1995

[Dynamics of IL-2 and IFN-gamma levels induced by sea or Con A in spleen cells of Schistosoma japonicum-infected mice].

The capacity of mitogen Con A and SEA-stimulated spleen cells to produce cytokines IFN-gamma and IL-2 was studied in S. japonicum-infected mice every two weeks from 0 to 14 wk after infection. The results showed that the levels of these two cytokines began to rise at the 4th wk after infection and reached a peak level at 6-8 wk, then declined to the levels similar to those pre-infection at 12-14 wk after infection. The IFN-gamma level reached the peak earlier than the IL-2 level. The dynamics of cytokine level in both mitogen and antigen-stimulated group was similar. The results suggest that IL-2 and IFN-gamma might be the essential cytokines involved in egg granuloma formation in schistosomiasis japonica.

Animals↗

PubMed1995

[Influences of capsaicin and electroacupuncture at "point" on acetylcholine (ACh) release in the spinal dorsal horn of rats].

The dynamic changes of ACh activity in the spinal dorsal horn of rats were recorded by ACh ion selective microelectrodes. The influence of applying capsaicin to the spinal surface, administering anti-SP surum to the interior of dorsal horn, cutting off dorsal roots and electroacupuncturing at "points" on the ACh activity were studied. The results showed that electroacupuncture at "points" and capsaicin could facilitate ACh release of the spinal dorsal horn, it was fully inhibited by cutting off dorsal roots or obviously inhibited by administering anti-SP surum. The above results indicated that ACh might participate in the primary afferent of painsensation and acupuncture sensation as a neurotransmitter and SP might adjust the release of ACh in spinal dorsal horn.

Acetylcholine↗

PubMed1995

[The sensitizing role of the anti-idiotypic monoclonal antibody-NP30 of Schistosoma japonicum in egg granuloma formation].

C57BL/6 mice sensitized intraperitoneally with the anti-idiotypic monoclonal antibody-NP30 of Schistosoma japonicum and then injected with vital egg suspension directly into spleen were used as the experimental models of hepatic egg granulomas in this study. The soluble egg antigen(SEA) sensitized group was used as positive control and the SP2/0 ascites injected group as negative control. The results showed that the size and volume of hepatic egg granulomas in the NP30 sensitized group increased obviously 4 days after egg injection and that a large number of eosinophiles appeared in egg granulomas. The size and volume of egg granulomas reached the peak values at d8 and d15 after egg injection, respectively. The peak values of the NP30 sensitized group were similar to those of the SEA sensitized group (P > 0.05). The size and volume of egg granulomas in the SP2/0 ascites injected group did not reach the peak values, which were less than those of the group sensitized with NP30 (size: P < 0.05; volume: P < 0.01), until d32 after egg injection. Our study suggests that NP30 may play a sensitizing role in the formation of hepatic egg granulomas.

Animals↗

PubMed1994

Age related changes of social memory/recognition in male Fischer 344 rats.

Two different habituation-dishabituation test paradigms were used to evaluate differences in social memory/recognition among 3-, 15- and 22-month-old male Fischer 344 rats. For test 1, males received three 2-min exposures to the same stimulus ovariectomized female, followed by three 2-min exposures to a different stimulus female with an inter-trial interval of 6 min. All groups showed a habituation response with investigation times decreasing on trials 2 and 3. Introduction of a different stimulus female on trial 4 (dishabituation) resulted in significant differences with investigation times of the 3-month animals being significantly greater than both the 15- and 22-month animals and those of the 15- being greater than the 22-month animals. Notably, the 22-month-old animals failed to dishabituate on this task. For test 2, all animals received two trials with different stimulus females used in each trial. While investigation times of the 3-month animals remained elevated in trial 2, indicative of an absence of habituation to these different stimuli, those of the 15- and 22-month-old animals decreased significantly, suggesting that habituation had occurred to the task and these animals failed to recognize differences in the stimuli. Taken together, these results demonstrate that the 22-month-old rats show enhanced habituation, but markedly deficient dishabituation responses compared to the 3-month-old animals, while the performance of the 15-month animals was intermediate. These results suggest an age dependent decrement in social memory/recognition processes in the male Fischer 344 rat.

Aging↗

PubMed1994

Phorbol 12-myristate 13-acetate stimulates proliferation and ductal morphogenesis and inhibits functional differentiation of normal rat mammary epithelial cells in primary culture.

The effect of the tumor promoter phorbol 12-myristate 13-acetate (PMA) on proliferation and differentiation of normal mammary epithelial cells from 50-day-old virgin rats was investigated using a model system that allows for full morphological and functional development of the cells. In this model, mammary epithelial cells are grown within a reconstituted basement membrane in a defined serum-free medium. PMA at a concentration of 10(-6) M effected translocation of protein kinase C from cytosol to membrane. At the same concentration, it stimulated cell proliferation both in the presence and absence of EGF, and this stimulation was observed even when PMA exposure was limited to 15 min at the time of each media change. In contrast to the effect on proliferation, PMA at concentrations of 10(-7) and 10(-6) M inhibited functional differentiation as assessed by casein accumulation. Phorbol 12,13-dibutyrate at 10(-6) M also stimulated proliferation and inhibited casein accumulation and was more effective than PMA in both cases. In contrast, the nonactive tumor promoter 4-alpha PMA had no effect on either proliferation or differentiation. One of the most striking effects of PMA was its ability to stimulate an atypical ductal morphogenesis, as manifested by the formation of intricate web-like colonies, and to inhibit the development of the well-differentiated alveolar-like multilobular colonies. PMA was also shown to completely suppress the growth of the squamous-like colonies that develop when EGF is absent or deficient. These effects of phorbol esters in mammary epithelial cells to stimulate proliferation, inhibit functional differentiation, and stimulate the development of ductal colonies are consistent with the suggestion that the signal transduction pathways evoked by PMA could act to stimulate the growth of initiated cells or render normal cells more sensitive to carcinogen.

Animals↗

PubMed1994

L-dopa reverses castration-induced disruption of dishabituation responses to female chemical cues in male rats.

In the present experiment, habituation/dishabituation behavioral tests were conducted to measure discriminatory olfactory recognition responses to chemical cues among control, castrated, and castrated+L-3,4-dihydroxyphenylalanine (L-DOPA)-treated male rats. Castration produced a disruption of dishabituation responses to female urine, and this effect was reversed by treatment with L-DOPA. In the posterior olfactory bulb, 3,4-dihydroxyphenlacetic acid (DOPAC) levels were significantly increased in L-DOPA-treated animals compared with the vehicle-treated control and castrated groups. No significant differences in olfactory bulb norepinephrine or dopamine concentrations among the three treatment groups were obtained. The restoration of behavioral dishabituation responses following L-DOPA treatment suggests that the catecholaminergic system of the olfactory bulb may play a critical role in the recognition and possibly attractions for or preferences to female chemical cues.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1994

Loss of gap junctions from DDT-treated rat liver epithelial cells.

The mechanism by which the liver tumor promoter 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT) inhibits gap junctional intercellular communication (GJIC) in WB-F344 rat liver epithelial cells could involve gap junction loss and/or decreased gap junction channel permeability. We examined these two possibilities in the present study. Immunohistochemical studies using antibodies specific to connexin43, the major gap junction protein expressed by these cells, revealed that gap junction number and size were reduced during exposure to DDT. The reductions in gap junctions (33-91%) correlated with dose-dependent (1-10 microM) and time-dependent (0.5-4 h) decreases in cell-to-cell fluorescent dye-coupling (64-85%), as well as cellular levels of phosphorylated connexin43. These effects were reversible following removal of the tumor promoter from the culture medium, although cycloheximide reduced the level of gap junction reformation. The losses in gap junctions were not due to decreased connexin43 gene expression since steady-state levels of connexin43 mRNA were not similarly affected by DDT. Fenarimol (10 microM), a structural analog of DDT, did not inhibit GJIC and had no effect on gap junction structure or connexin43 expression. These data suggest that the inhibition of GJIC by DDT resulted from the removal of gap junctions from the plasma membrane and their degradation rather than simply a decrease in their permeability.

Animals↗