Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 1,009 records · Page 56Linked to original sources

PubMed1992

Neuroendocrine responses to the serotonin2 agonist DOI are differentially modified by three 5-HT1A agonists.

Evidence suggests that activation of 5-HT1A receptors leads to inhibition of 5-HT2-mediated behavior. The purpose of this study was to investigate the interaction between 5-HT1A and 5-HT2 receptor-mediated hormone secretion. Rats were pretreated with the 5-HT1A agonists buspirone (0, 0.5, 2.0 mg/kg, i.p.), 8-OH-DPAT (0, 0.05, 0.2 mg/kg, s.c.) or ipsapirone (0, 1.0, 2.5 mg/kg, i.p.), 45 min before decapitation. The 5-HT2 agonist DOI was administered (0-10 mg/kg, i.p.) 15 min after injection of the 5-HT1A agonists. The three 5-HT1A agonists differentially altered the DOI-induced increase of concentrations of hormone in plasma. None of the three 5-HT1A agonists influenced the basal levels of renin, ACTH and prolactin but 8-OH-DPAT and buspirone increased the basal level of corticosterone in plasma. Also, 8-OH-DPAT increased the effects of DOI on the concentration of ACTH in plasma but ipsapirone and buspirone did not. None of the 5-HT1A agonists significantly affected DOI-induced increase of concentration of corticosterone in plasma. Buspirone and 8-OH-DPAT potentiated the effect of DOI on prolactin in plasma, but ipsapirone did not. Ipsapirone potentiated the effect of DOI on the concentration of renin in plasma but this effect was not observed in 8-OH-DPAT- and buspirone-pretreated rats. The results do not support the hypothesis for a functional interaction between 5-HT1A and 5-HT2 receptors, since the three 5-HT1A agonists did not have the same influence on the hormonal effects of DOI.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1992

Evaluation of four different immunogens for the production of snake antivenoms.

Four different immunogens were used to produce polyvalent antivenom in rabbits to the venoms of Bothrops atrox, Crotalus atrox, Crotalus adamanteus and Crotalus durissus terrificus. The immunogens were: (1) unfractionated mixture of the four crude venoms, and three fractions of the mixture as follows, (2) HPLC gel filtration high (> 50,000) mol. wt fraction, (3) HPLC gel filtration medium (14,000-50,000) mol. wt fraction, and (4) HPLC gel filtration low (< 14,000) mol. wt fraction. The resultant immune sera were compared with commercial antivenom (Wyeth, polyvalent Crotalidae) for total IgG content, ELISA reactivities, patterns of Western blots and ability to neutralize lethal and local hemorrhagic activities of the four venoms. The results indicate that the rabbit antivenoms had significantly higher ELISA reactivity and blotting signals than Wyeth antivenom. However, neither ELISA nor Western blotting signals correlated with the ability of the antivenoms to neutralize the lethal or hemorrhagic activities of the venoms. The protective ability of the antivenoms varied considerably. In general, antivenoms generated by using fractionated venoms as immunogens exhibited greater protective ability than antivenom produced by using the mixture of four venoms as immunogen. Some of the antivenoms provided greater or comparable protective ability for certain venoms when compared to Wyeth antivenom. It appears that the use of certain venom fractions as immunogens is a promising alternative for production of effective antivenoms.

Animals↗

PubMed1992

Association between mast cells and the development of experimental autoimmune uveitis in different rat strains.

To study the role of anterior uveal mast cells in experimental autoimmune uveitis (EAU), the mast cells in the iris and ciliary body of Lewis rats, Brown Norway (BN) rats, and their F1 hybrids (LBNF1) were quantitated in normal rats and during the induction period of EAU. The mean baseline mast cell number was 68.9 +/- 10.8 per anterior uvea for Lewis rats, 0.3 +/- 0.2 for BN rats, and 4.6 +/- 0.6 for LBNF1 rats. Detectable mast cells in the anterior uvea of S-Ag-immunized Lewis rats decreased to 60% of control at 6 days postimmunization, recovered to 80% at 10 days, and dropped again to 16% at 13 days, with disease onset around 14 days. In Lewis rats that were adoptively transferred with a uveitogenic T-lymphocyte line, a profound drop in anterior uveal mast cell numbers occurred in the eyes with early signs of EAU, 3 days after the transfer. The decrease in detectable mast cells is consistent with mast cell degranulation. The data suggest that anterior mast cells participate in the immunopathogenesis of EAU and may influence the genetic susceptibility to EAU.

Animals↗

PubMed1992

Cocaine-induced suppression of renin secretion is partially mediated by serotonergic mechanisms.

Acute cocaine reduces renin secretion. To determine whether serotonergic neurons mediate this effect, male Sprague-Dawley rats received the serotonin (5-HT) neurotoxin 5,7-dihydroxytryptamine (75 micrograms/side, ICV) 2 weeks prior to cocaine injections (3.75-15 mg/kg, IP). 5-HT lesions attenuated the cocaine-induced reduction of plasma renin concentration (PRC), suggesting a partial 5-HT role. To determine which receptors mediate this response, rats were pretreated with the partial 5-HT1A agonist 8-[2-[4-(2-methoxyphenyl)-l-piperazinyl]ethyl]-8-azaspirol-[4,5]- decane-7,9-dione (BMY 7378) (1 mg/kg, SC), the 5-HT1C/5-HT2 antagonist ritanserin (0.1 mg/kg, SC), or the alpha 2/5-HT1A antagonist yohimbine (1 mg/kg, SC) prior to cocaine. None of the antagonists altered the cocaine-induced suppression of PRC, although BMY 7378 and yohimbine elevated PRC. The data suggest that cocaine's effect is partially mediated by a serotonergic mechanism, but do not support a role for 5-HT1A receptors, 5-HT2/5-HT1C receptors, or alpha 2-adrenoceptors in mediating the suppressive effect of cocaine on renin secretion.

5,7-Dihydroxytryptamine↗

PubMed1992

Binding of carbamyl-platelet-activating factor to the Raji lymphoblast platelet-activating factor receptor.

Carbamyl-platelet-activating factor (1-hexadecyl-2-N-methylcarbamyl-glycero-3-phosphocholine; CPAF) is an analog of platelet-activating factor (PAF) containing an N-methylcarbamyl moiety at the sn-2 position. CPAF was tested for effects on the Raji lymphoblast PAF receptor. Binding studies conducted at 4 degrees C demonstrated specific binding that reached saturation within 60-80 min. Scatchard analysis of CPAF binding data revealed a single class of CPAF binding sites (14,800/cell) with a K = 2.9 +/- 0.9 nM. Competition binding studies with PAF indicated that CPAF has about one-third the potency of native PAF. Unlike PAF, however, CPAF was not significantly metabolized by Raji lymphoblasts at 37 degrees C. CPAF was shown to have PAF-agonistic qualities, since 100 pM to 1 microM CPAF increased free intracellular calcium in a dose-dependent manner. The structurally dissimilar PAF receptor antagonists CV-6209 and alprazolam inhibited the CPAF-induced calcium changes at doses that competed with CPAF binding. Treatment of Raji lymphoblasts with PAF or CPAF (10 pM-1 microM) did not affect spontaneous proliferation, suggesting that the PAF receptor is not involved in the proliferative process in this cell line. These studies demonstrate that CPAF is a metabolically stable lymphoblast PAF receptor agonist that may provide a useful tool in the further elucidation of the role of PAF in lymphocyte function.

Burkitt Lymphoma↗

PubMed1992

Cocaine-induced suppression of renin secretion is mediated in the brain: investigation of cardiovascular and local anesthetic mechanisms.

Acute cocaine reduces renin secretion. To determine a peripheral versus central site of action, intracerebroventricular (ICV) versus intraperitoneal (IP) injections of cocaine were compared. Cocaine was more potent reducing plasma renin activity (PRA) and concentration (PRC) when injected ICV (0.050 mg/kg) than IP (5 mg/kg), suggesting a central site of action. Furthermore, addition of cocaine (10(-4) M) to kidney slices in vitro did not influence renin release, indicating that cocaine does not suppress renin secretion by acting directly in the kidney. We also investigated whether the hypertensive or local anesthetic properties of cocaine mediate its inhibition of renin secretion. Therefore, we compared the cardiovascular and endocrine effects of cocaine with those of the local anesthetic drug procaine. Both cocaine and procaine (500 micrograms/kg, ICV) produced rapid and short-term increases in blood pressure, but cocaine decreased PRC whereas procaine increased PRC. Intra-arterial (IA) and IP injections of cocaine also reduced PRC whereas procaine had no effect (IA) or elevated PRC (IP). Together, the data suggest that cocaine decreases renin secretion by acting in the brain. It is not likely that the cardiovascular or local anesthetic actions of cocaine are the main cause of its suppressive effect on renin secretion.

Anesthetics, Local↗

PubMed1992

A rapid method for detection of Yersinia enterocolitica serotype O:3 in pig feces using monoclonal antibodies.

A simple colony immunoblotting method using monoclonal antibodies (MAbs) was developed to detect Y. enterocolitica serotype O:3 in pig feces. One of the MAbs studied was able to detect single colonies of the organism in the presence of calculated 3.1 x 10(8) heterologous organisms in pig feces. The MAb was found to be specific for the lipopolysaccharide (LPS) O-antigens of Y. enterocolitica serotype O:3. No significant cross-reactivity was found against a variety of closely related serotypes and Gram-negative organisms. The MAb could also be used in a slide agglutination test and an indirect fluorescence antibody assay for rapid identification of Y. enterocolitica serotype O:3.

Agglutination Tests↗

PubMed1992

Effects of various noise exposures on endocochlear potentials correlated with cochlear gross responses.

Changes in endocochlear potentials (EP), cochlear microphonics (CM), and compound action potentials (CAP) with noise exposure were investigated in guinea pigs. The animals were anesthetized and immobilized and exposed to white noise at intensities ranging from 105 to 125 dB. The negative EP (N-EP) was induced by anoxia and was investigated during and after noise exposure. It was found that the general EP (G-EP, the sum of both positive EP (P-EP) and N-EP) increased remarkably during exposure to 115 dB noise but decreased during exposure to 125 dB noise. A smaller absolute value of N-EP was encountered only during exposure to 125 dB noise. The results shed light on the relationship between EP and CM, CAP changes, and the potential mechanism of EP change and its significance in noise-induced hearing loss.

Acoustic Stimulation↗

PubMed1992

Enhancement of S-antigen and its mRNA in the irides of uveitic patients.

S-antigen (S-Ag) and its mRNA were analysed by immunohistochemistry and in situ hybridization in 32 iridectomy specimens from 29 uveitic patients and 10 non-uveitic patients. S-Ag was detected in one iris and its mRNA was detected in 12 uveitic patients. Neither S-Ag nor its mRNA was found in the controls (P < 0.003). Ten of the 12 patients who had detectable S-Ag mRNA, while only four of the 17 patients who did not, had received corticosteroids for more than 3 years (P = 0.006). We also demonstrated S-Ag and its mRNA in bovine iris by immunoprecipitation and polymerase chain reaction. These results indicate that S-Ag and its mRNA accumulate in the irides of some uveitic patients. This accumulation may be the result of local immunoregulatory factors and an effect of corticosteroid treatment, and may modulate ocular inflammation.

Adrenal Cortex Hormones↗

PubMed1992

Computer detection of the rapid diffusion of fluorescent membrane fusion markers in images observed with video microscopy.

We have developed an algorithm for automated detection of the dynamic pattern characterizing flashes of fluorescence in video images of membrane fusion. The algorithm detects the spatially localized, transient increases and decreases in brightness that result from the dequenching of fluorescent dye in phospholipid vesicles or lipid-enveloped virions fusing with a planar membrane. The flash is identified in video images by its nonzero time derivative and the symmetry of its spatial profile. Differentiation is implemented by forward and backward subtractions of video frames. The algorithm groups spatially connected pixels brighter than a user-specified threshold into distinct objects in forward- and backward-differentiated images. Objects are classified as either flashes or noise particles by comparing the symmetries of matched forward and backward difference profiles and then by tracking each profile in successive difference images. The number of flashes identified depends on the brightness threshold, the size of the convolution kernel used to filter the image, and the time difference between the subtracted video frames. When these parameters are changed so that the algorithm identifies an increasing percentage of the flashes recognized by eye, an increasing number of noise objects are mistakenly identified as flashes. These mistaken flashes can be eliminated by a human observer. The algorithm considerably shortens the time needed to analyze video data. Tested extensively with phospholipid vesicle and virion fusion with planar membranes, our implementation of the algorithm accurately determined the rate of fusion of influenza virions labeled with the lipophilic dye octadecylrhodamine (R18).

Algorithms↗

PubMed1992

Hepatic gene therapy: persistent expression of human alpha 1-antitrypsin in mice after direct gene delivery in vivo.

The liver represents an excellent target organ for gene therapy. The current strategy for hepatic gene therapy involves the isolation of primary hepatocytes from a resected liver lobe, transduction of therapeutic genes in vitro followed by autologous hepatocellular transplantation. This ex vivo approach is a rather complex procedure in its entirety; thus, a simple method for direct gene delivery into hepatocytes in vivo has been developed. The procedure involves partial hepatectomy followed by the portal vein infusion of recombinant retroviral vectors. Histological analysis of hepatocytes after in vivo delivery of a recombinant retrovirus bearing the E. coli beta-galactosidase gene showed that 1-2% of the parenchymal cells were transduced. Direct hepatic transfer of human alpha 1-antitrypsin cDNA under the transcriptional direction of the albumin promoter-enhancer led to constitutive expression of the human protein in the sera of recipients at concentrations of 30-1,400 ng/ml for at least 6 months. The experimental animals showed no signs of illness and histologic analysis of the liver revealed no evidence of pathologic abnormalities. The results suggest that the in vivo approach is an attractive alternative for hepatic gene therapy.

Albumins↗

PubMed1992

On the Penrose hypothesis on fingerprint patterns.

Penrose hypothesized that fingerprint patterns such as loops, whorls, etc. are formed by ridges corresponding to the lines of curvature of the skin of the embryo at the time when the ridges were being formed. Under this hypothesis, Smith (1979) has shown analytically how some patterns emerge. In this paper it is shown that (i) Smith's differential equation has an exact solution and (ii) the extension given here supplies the remaining important patterns.

Dermatoglyphics↗

PubMed1992

Allergic contact dermatitis in shiitake (Lentinus edodes (Berk) Sing) growers.

A 42-year-old female shiitake grower was investigated to clarify the etiology of skin lesions which developed during the planting of shiitake hyphae into bed logs. She complained of repeated eczematous skin lesions during the planting season, from March to July, for 10 years. She handled 7,000 pieces of small conic blocks made of beech, with shiitake hyphae attached to their surface, per day, and 300,000 pieces altogether per season. She was positive on patch testing with extracts of shiitake hyphae. In contrast, female shiitake growers with skin lesions associated with work other than planting, and without skin lesions, were negative on patch testing to the hyphae. Moderate allergenicity was observed to extracts of shiitake hyphae in a guinea pig maximization test. These findings indicated the etiology of skin lesions in shiitake growers to be allergic contact dermatitis induced by shiitake hyphae.

Adult↗

PubMed1992

Evaluation of contact allergy to chemicals using laser Doppler flowmetry (LDF) technique.

Skin blood flow in allergic contact reactions and cross-sensitivity were evaluated using laser Doppler flowmetry (LDF) to study the dose-response relationships in phases of induction and challenge in guinea pigs. Guinea pigs were sensitized with different doses of 1-chloro-2,4-dinitrobenzene (DNCB) and challenged with different doses of DNCB and 2,4-dinitrobenzene sulfonic sodium salt (DNBS). The skin reactions were evaluated by LDF and visual reading score. The results indicated that there were dose-response relationships between the doses of DNCB and LDF measurements in both phases of induction and challenge, that there was a cross-reaction between DNCB and DNBS, and that the reactions at 24 h were greater than that at 48 h after removal of the patches. LDF may discriminate between positive patch test reactions and negative or doubtful reactions, but not between weak positive and strong positive reactions. This is because vascular dilatation and increase of flow already reaches a maximum in weak reactions. The more advanced phases are dominated by oedema formation. This is simply the nature of the inflammatory reaction, rather than a methodological error. The important point is that LDF can separate positive reactions from negative/uncertain reactions. The results indicated that LDF, as a non-invasive technique, may objectively and quantitatively evaluate the dose-response relationships of contact sensitivity of sensitizers.

Animals↗

PubMed1992

Study of dose-response relationship in contact sensitivity using an in vitro assay.

Dose-response relationships in contact sensitivity were evaluated in guinea pigs using an in vitro assay. Guinea pigs were sensitized with different doses of 1-chloro-2,4-dinitrobenzene (DNCB) and challenged with DNCB and 2,4-dinitrobenzene sulfonic salt (DNBS). Lymph node cells from sensitized and control guinea pigs were cultured in the presence of different doses of DNCB and DNBS at 8 x 10(5) cells/well, respectively. The sensitivity was evaluated by the lymphocyte transformation test (LTT), which was assessed by uptake of 3H-thymidine. The results indicated that there were significant correlations between the doses of sensitizers and the values of LTT in both phases of induction and challenge. Thus, the presence of higher numbers of LTT-reactive lymphocytes in the circulation may well correlate with the sensitizing doses. The values examined by in vitro assay correlated well with patch test readings (r = 0.653), indicating that following the increment of degree of patch test reactions, the values of SI were also increased. The in vitro LTT may discriminate between positive patch test reactions and negative or doubtful reactions, but not between weak positive and strong positive reactions. The in vitro assay reproduced the cross-reaction between DNCB and DNBS which was confirmed in vivo.

Animals↗

PubMed1992

Mechanisms of airway protection and upper esophageal sphincter opening during belching.

The mechanisms of airway protection, upper esophageal sphincter (UES) opening, and their coordination during belching were studied with a concurrent videoendoscopic, videofluoroscopic, and manometric technique. Analysis of videoendoscopic recordings revealed that glottal function during gastric and esophageal belching was similar and consisted of vocal cord adduction resulting in closure of intoitus to trachea, followed by anterior-caudad movement of the glottis, followed by slitlike or triangular UES opening. When a belch episode was associated with an intragastric pressure increase, in addition to the above features, there was approximation of arytenoids to the base of the epiglottis before the UES opened. Duration of vocal cord closure during belches induced by 40 ml intraesophageal air injection was significantly longer than belches induced by 20 ml (P less than 0.01). Vocal cord closure preceded the UES opening invariably. Analysis of videofluoroscopic recordings showed that hyoid bone movement during belching had a distinctive pattern different from its movement during swallowing. UES opening started generally when the hyoid bone was pulled anteriorly. Anterior hyoid excursion of 0.78 +/- 0.1 cm during belching was significantly shorter than its excursion of 1.8 +/- 0.09 cm during swallowing (P less than 0.01). We conclude that glottal closure is an integral component of both esophageal and gastric belch reflexes that prevents aspiration of regurgitated material into the airway. Glottal closure mechanism during belching has two tiers of closure: 1) vocal cord closure and 2) aryepiglottic approximation. Glottal and UES functions are closely coordinated during belching, and finally, during belching, UES is pulled open after its relaxation.

Adult↗

PubMed1992

Coordination of deglutition and phases of respiration: effect of aging, tachypnea, bolus volume, and chronic obstructive pulmonary disease.

The effects of aging, tachypnea, bolus volume, and chronic obstructive pulmonary disease on the coordination of swallowing with the phases of respiration were studied by concurrent respirography and submental surface electromyography. Study findings showed that in young healthy volunteers, during rest, there is preferential coupling of subconscious swallowing with the expiratory phase of continuous respiration. This preferential coupling of swallowing with expiration was found to increase relative to other phases of respiration during water swallows and tachypnea (P < 0.05). Respiratory phase occurrence of swallowing and postdeglutitive resumption of respiration during exacerbation of chronic obstructive pulmonary disease was found to be significantly different compared with the basal state (P < 0.05). Respiratory phase occurrence of subconscious swallowing in the elderly was found to be different from the young (P < 0.05). Position had no significant effect on the coordination of swallowing and phases of respiration. We concluded that in resting young volunteers the majority of deglutitions are coupled with the expiratory phase of swallowing. This coupling is increased in frequency by the presence of a liquid bolus and tachypnea. And finally, age and chronic obstructive pulmonary disease alter this coordination significantly.

Adult↗

PubMed1992

Immunopathology of experimental autoimmune uveoretinitis in primates.

The eyes and pineal glands from 10 monkeys immunized with S-antigen were studied using routine histopathological and immunohistochemical techniques. Seven out of 10 animals developed uveitis between 19 and 33 days after the initial immunization. Histopathology of the eyes harvested 70 days after immunization showed moderate to marked uveoretinitis, subretinal fibrosis, retinal necrosis and gliosis. The pineal glands demonstrated chronic pinealitis. The infiltrating cells were both CD3 and CD19/CD22 lymphocytes with a ratio of 1.4 in the eye and 2.2 in the pineal gland. The ratio of CD4 to CD8 lymphocytes was 1.5:1. MHC Class II antigens and adhesion molecule (ICAM-1) were observed on resident cells. The influx of B lymphocytes and the formation of subretinal fibrosis differentiate the disease in the monkey from that in the rat and mouse. These findings are similar to Vogt-Koyanagi-Harada syndrome and subretinal fibrosis with uveitis syndrome in human.

Animals↗