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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 973 records · Page 54Linked to original sources
PubMed1993

Neurons in the hypothalamic paraventricular nucleus mediate the serotonergic stimulation of prolactin secretion via 5-HT1c/2 receptors.

These studies examined the hypothalamic site and receptor subtype mediating the serotonergic (5-HT) control of PRL secretion in conscious male rats. Initially, we characterized the pharmacology of the 5-HT releaser and 5-HT agonists that increase PRL release. Subsequently, we performed lesion experiments to locate the 5-HT receptors involved in PRL secretion. p-Chloroamphetamine, a 5-HT releaser, is postulated to enter serotonergic nerve terminals through the 5-HT uptake mechanism, which can be inhibited by fluoxetine. p-Chloroamphetamine (8 mg/kg, ip) increased the plasma PRL concentration approximately 6-fold. The 5-HT uptake inhibitor fluoxetine almost completely prevented this increase, demonstrating that p-chloroamphetamine increases PRL release via a serotonergic mechanism. The 5-HT1C/5-HT2 agonist +(-)-1-(2,5-dimethoxy-4-iodophenyl)2-aminopropane HCl (ip) produced a strong (30-fold) dose-dependent elevation of plasma PRL, which was virtually eliminated by 0.1 mg/kg (sc) ritanserin, a 5-HT1C/5-HT2 antagonist. +(-)-1-(2,5-Dimethoxy-4-iodophenyl)2-aminopropane HCl injected intracerebroventricularly (icv) in doses below those that were peripherally effective also produced a significant (8-fold) increase in PRL secretion that was again attenuated by icv pretreatment with ritanserin (2 micrograms/kg). RU 24969 (5-methoxy-3-[1,2,3,4-tetrahydro-4-pyridinyl]1H-indole) was reported to act as both a 5-HT releaser and a direct postsynaptic 5-HT agonist. To test whether RU 24969 releases 5-HT to increase PRL secretion, we depleted 5-HT stores with the 5-HT synthesis inhibitor p-chlorophenylalanine. The ability of RU 24969 (0.5, 1, 5, and 10 mg/kg, ip) to elevate PRL secretion was not inhibited by pretreatment with p-chlorophenylalanine, suggesting that RU 24969 stimulates PRL secretion only through activation of postsynaptic 5-HT receptors. To test whether RU 24969 acts centrally, it was injected either icv, through chronic icv cannulae, or peripherally (ip). RU 24969 injected icv significantly stimulated PRL secretion (11-fold) at doses 500-fold lower than the peripherally effective doses (10 micrograms/kg vs. 5 mg/kg), suggesting a role for central 5-HT receptors in the regulation of PRL secretion. In addition, rats pretreated with the 5-HT1C/5-HT2 antagonist LY53857 (icv) significantly inhibited the PRL response if RU 24969 was injected ip, but not icv. The results of these experiments suggest that 5-HT1C or 5-HT2 receptors in the brain participate in the serotonergic stimulation of PRL secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Amphetamines↗
PubMed1993

Polysaccharide microcapsules and macroporous beads for enhanced chromatographic separation.

One recent solution to the diffusion problem found in conventional chromatographic separation is the use of dual porosity beads in which large pores allow for convective flow and smaller pores allow for molecular diffusion. In our studies, dual porosity beads were prepared from carrageenan using an emulsion method. Effects of polymer type, polymer concentration, toluene content, gelling temperature, and stirring speed on the structure of porous beads were investigated. In an alternative approach, one of the interacting molecules in affinity chromatography, can be entrapped within semipermeable microcapsules. This has the advantage of increased adsorption capacities. Using blue dextran and albumin as a model system, alginate-chitosan capsules, containing blue dextran, were employed in the recovery of albumin from a saline solution.

Alginates↗
PubMed1993

An immunohistochemical study of Langerhans cells, T-cells and the HLA antigen in human cornea.

The distribution of Langerhans cells (LC), T-cell subsets and HLA antigen in 12 normal and 7 morbid corneas, including 4 of suppurative corneal ulcer and 3 of uveogenic endophthalmitis, was investigated with monoclonal antibodies. The results revealed that a small amount of LC and T-cell subsets were present in the limbal region of normal corneas, while large numbers of LC and OKT4+ were observed in the corneas of suppurative ulcer. HLA-A, B, C antigens were expressed on the epithelial cells and keratocytes of the normal corneas, while the HLA-DR antigens were expressed on the surface of LC at the limbus.

Adolescent↗
PubMed1993

[Formation of mouse chimeras from early embryonic pluripotential stem cell].

Three chimeric mice were produced by injecting the embryonic stem cell-CCE cells into the cavity of 3.5 day host blastocysts from Kunming and C57BL/6J mice. By analyses of glucose phosphate isomerase (GPI-1), the results show a contribution from CCE cells in heart tissue of female Kunming chimera. Breeding experiments demonstrated that all chimeric mice were fertile but none of 3 chimeras produced germ line transmission.

Animals↗
PubMed1993

[Radiation protection effects of sinapine on Drosophila melanogaster in a sex-linked recessive lethal test system].

It has been shown that the radiation resistance of some cruciferous plants is related to some natural radiation protection substances in these plants. Sinapine, which has shown radiation protection effects on barley, wheat and mouse, is one of such substances distributed in cruciferous plants. In this paper, the radiation protection effects of sinapine on Drosophila melanogaster in a sex-linked recessive lethal (SLRL) test system were observed. The sinapine solution could be fed to the D. melanogaster (Oregon K). 40 Gy X-irradiation induced SLRL mutation rate of 8.96%. However, if 10 mg/ml sinapine which was found to have no physiological toxicity or harmful effects on its reproductive function, was fed before 40 Gy X-irradiation, the SLRL mutation rate could be reduced to 0.40%, which was within the range of spontaneous SLRL mutation rate of Oregon K Drosophila, i.e. 0-0.4%. The potential of the using of the very strong radiation protection effects of sinapine in anticarcinogenesis was also discussed.

Animals↗
PubMed1993

[Effect of hyperglycemia on insulin release from isolated rat pancreatic islets].

We investigated the long-term (24h) influence of high concentration glucose (26.4mmol/L) on insulin release by culturing collagenase isolated rat pancreatic islets in vitro. The cultured islets were morphologically normal by histological examination. Compared with freshly isolated islets, islets cultured in 26.4mmol/L glucose showed higher basal insulin release (P < 0.05). The effect of high glucose was time dependence. When islets preexposed to high glucose medium for 24h were perfused, the basal insulin release was significantly higher than that of freshly isolated islets, the first-phase glucose stimulated insulin release disappeared, and the second-phase was diminished. Islets cultured in high glucose medium showed increased sensitivity to L-arginine. Long-term high concentration glucose could potentiate the arginine-induced release. When added to the culture medium with 26.4mmol/L glucose, Ginseng saponins markedly increased the responsiveness of islets to glucose stimulation, and augmented the sensitivity of incubated islets to additional Ginseng saponins.

Animals↗
PubMed1993

Effect of acupuncture and point-injection treatment on immunologic function in rheumatoid arthritis.

The results of treatment of 54 cases of rheumatoid arthritis (RA) by warm needling (WN) and point-injection (PI) with Zhuifengsu are reported. Good clinical results were observed with an effective rate of 100%. At the same time, changes in cellular and humoral immunity and other parameters in peripheral blood were noted before and after treatment. The NK activity and IL-2 value in RA patients were found to be lower than those of normal individuals; both increased after treatment (P < 0.01). This suggests that the WN and PI with Zhuifengsu exert a regulatory effect on the cellular immunological function.

Acupuncture Points↗
PubMed1993

An antibody adsorption technique facilitates antigen selection for development of serotype-specific monoclonal antibodies to Yersinia enterocolitica.

A simple procedure is described to aid in the selection of antigens from gram-negative organisms that are most likely to exhibit serotype-specific epitopes when used as immunogens in the mouse. Several such proteins of Yersinia enterocolitica serotype O:8 were identified by immunoblotting through their binding to polyclonal antibodies that remained in immune serum after the serum had been adsorbed with common antigens prepared from a variety of closely related serotypes and Gram-negative organisms. The selected proteins were purified electrophoretically and used to immunize mice to obtain immune spleen cells for cell fusions. Serotype-specific monoclonal antibodies (MAbs) were successfully developed to a 36-kDa outer membrane protein resembling the porin OmpF. Additional MAbs also were produced that cross-reacted with other serotypes. Only cross-reactive epitopes were detected on a 34-kDa protein. The MAbs were used to show that the relative expression of the 36-kDa protein varied severalfold according to the medium used to grow the cells. These MAbs are promising agents for serological identification of Y. enterocolitica serotype O:8. The procedure should be useful in many situations where extensive cross-reactivities impede generation of highly specific MAbs.

Adsorption↗
PubMed1993

Evaluation of new therapy for eradication of H. pylori infection in nude mouse model.

OBJECTIVES: developing a new therapy for eradication of H. pylori by using the nude mouse model. METHODS: By quantifying the number of colonies of Helicobacter pylori and the score of H. pylori-associated gastritis from the gastric tissue following different drug regimens in inoculated nude mice, we evaluated the effectiveness of each regimen, including a new drug, plaunotol. Drugs were administered daily for a 1-wk period, beginning 4 wk after inoculation. RESULTS: In the examination after therapy, the number of colonies of H. pylori and the score of gastritis in the triple-therapy group were significantly lower than in any of the singly- and dual-drug groups or control group from 5 wk to the end of the study after inoculation. Inflammation of the stomach was less apparent in the treatment groups than in the control group. CONCLUSION: With the nude mouse model, we quantitatively demonstrated that the new triple therapy is the most effective therapy for eradication of H. pylori.

Amoxicillin↗
PubMed1993

Long-term treatment with the antidepressants fluoxetine and desipramine potentiates endocrine responses to the serotonin agonists 6-chloro-2-[1-piperazinyl]-pyrazine (MK-212) and (+-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI).

Various endocrine responses to 5-hydroxytryptamine (serotonin, 5-HT) agonists were used to assess serotonergic receptor function after chronic treatment with the antidepressants fluoxetine (10 mg/kg), a 5-HT uptake blocker and the norepinephrine uptake blocker desipramine (DMI, 5 mg/kg). Both were injected (i.p.) once a day for 21 days. DOI (5-HT1C/2 agonist, 0-5 mg/kg i.p.) and 6-chloro-2-[1-piperazinyl]-pyrazine (MK-212) (less selective, but predominantly a 5-HT1C agonist, 0-20 mg/kg i.p.) were administered 18 hr after the final antidepressant injection and 30 min before decapitation. Chronic treatment with both fluoxetine and DMI produced a potentiation in most hormone responses to the 5-HT agonists (+-)-1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane HCl (DOI) and MK-212, although there were several differences in individual hormone responses to the two 5-HT agonists. Fluoxetine and DMI potentiated the MK-212- and DOI-induced increase of plasma oxytocin levels and potentiated the effect of DOI on plasma adrenocorticotropic hormone (corticotropin) and prolactin levels. In contrast, the effect of the high dose of MK-212 on plasma prolactin concentration was reduced by both antidepressants. Only MK-212 increased vasopressin levels and this effect was potentiated by fluoxetine, but not by DMI. Fluoxetine also significantly increased the resting level of plasma vasopressin. DMI potentiated the effect of MK-212 on plasma renin concentration. Pretreatment with fluoxetine significantly increased (38%) the Bmax for the 5-HT1C/2 agonist sites ([125I]DOI) in the hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1993

The role of mast cells in endotoxin-induced uveitis.

PURPOSE: To investigate the role of mast cells in the induction of endotoxin-induced uveitis (EIU). METHODS: We previously showed that the mean mast cell number in the anterior uvea was greatest for Lewis rats, lowest for Brown Norway (BN) rats, and intermediate for LBNF1 rats. In the current experiment, we assessed the time of onset and severity of EIU in these three rat strains. We then studied changes in mast cell numbers in the anterior uvea during the induction period of EIU. RESULTS: Time of onset and severity of EIU were related to the number of mast cells in the anterior uvea. EIU occurred earliest in the Lewis rats, and the maximum mean grade of ocular inflammation on a scale of 0 (no inflammation) to 4 (severe inflammation) +/- standard error of the mean was 3.87 +/- 0.13 for Lewis rats, 1.06 +/- 0.06 for BN rats, and 1.19 +/- 0.12 for LBNF1 rats. The difference between the mean grade of inflammation in the Lewis rats and the other two strains was highly statistically significant (P < .001). In the Lewis rats, mast cell numbers +/- SEM decreased from 68.9 +/- 10.8 at baseline to 49.6 +/- 5.9 4 hr after lipopolysaccharide (LPS) injection and to 27.6 +/- 8.4 8 hr after LPS injection, suggesting that mast cell degranulation occurs before the development of EIU. CONCLUSION: Mast cells in the anterior uvea appear to potentiate endotoxin-induced ocular inflammation.

Animals↗