Biomedical subjects
Publications and source records attributed to A Guo.
In this paper is reported solid phase chemiluminescent immunoassay for insulin with N-(4-aminobutyl)-N-ethylisoluminol (ABE1) labelled antibody and a double antibodies sandwich procedure. ABEI-CoCl2-H2O2 was used as the chemiluminescent system and the linear range of insulin was 0.3-150 microU/tube. The correlation coefficient of the log-log regression equation was 0.985 and the absolute limit of detection 0.32 microU/tube.
We have studied the graft rejection of bovine lamellar cornea transplanted onto the rabbit cornea. In addition, the effect of inhibitors of arachidonic acid metabolism and immunosuppressive agents on this heterolamellar corneal transplant was investigated. The corneal lamellar transplant treated with saline were rejected at 9 +/- 1.4 day with 100% rejection rate. The postsurgical conjunctival hyperemia and edema occurred within 2-3 days. Corneal neovascularization took 5 to 9 days to reach the region of the graft. Intramuscular cyclosporin A (25mg/kg/day) and dexamethasone (0.1%) applied topically for 20 days (t.i.d.) inhibited the corneal opacity, edema, neovascularization and graft rejection. Topical Dexamethasone in the ipsilateral eye prolonged survival of grafts in the contralateral (untreated) eye. Cyclosporin A and dexamethasone probably inhibited the graft rejection process by their immunosuppressive action. Indomethacin and BW755C, respective cyclooxygenase and lipoxygenase inhibitors, applied topically did not inhibit graft rejection process while inhibiting postsurgical inflammatory response.
UNLABELLED: The experiment involved the transfer of lamellar corneas (0.3mm thick and 10mm diameter central epithelium with stroma) from fresh bovine eyes onto rabbits eyes. RESULTS: group 1, control, (4 rabbits), the donor corneas remained transparent for up to 7-10 days on the recipient rabbit eyes. After that time, all animals in this group rejected their grafts promptly. They showed markedly circumcorneal congestion, edema and vascularization of the cornea. Histopathology: There are apparently cellular infiltration of leukocytes in the grafts, and graft bed of the cornea, which are found also in the iris. Group 2: 3 rabbits were treated with 1% CsA in castor oil, 5 times per day. After 16 days, One of three rabbits showed mild rejection. Group 3: 4 rabbits were treated with CsA, I.M. 15 mg/kg/D. None has any immunological response to the grafts. The histopathology of group 2 and 3 shows no cellular infiltration, except one. CsA can 1. inhibit the rejection of the heterograft. 2. prolong the survive of the heterograft. 3. inhibit the vascularization. 4. has less side effects.
Races of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice, interact with cultivars of rice in a gene-for-gene specific manner. Multiple DNA fragments of various sizes from all strains of X. o. pv. oryzae hybridized with avrBs3, an avirulence gene from Xanthomonas campestris pv. vesicatoria, in Southern blots; this suggests the presence of several homologs and possibly a gene family. A genomic library of a race 2 strain of X. o. pv. oryzae, which is avirulent on rice cultivars carrying resistance genes xa-5, Xa-7, and Xa-10, was constructed. Six library clones, which hybridized to avrBs3, altered the interaction phenotype with rice cultivars carrying either xa-5, Xa-7, or Xa-10 when present in a virulent race 6 strain. Two avirulence genes, avrXa7 and avrXa10, which correspond to resistance genes Xa-7 and Xa-10, respectively, were identified and partially characterized from the hybridizing clones. On the basis of transposon insertion mutagenesis, sequence homology, restriction mapping, and the presence of a repeated sequence, both genes are homologs of avirulence genes from dicot xanthomonad pathogens. Two BamHI fragments that are homologous to avrBs3 and correspond to avrXa7 and avrXa10 contain a different number of copies of a 102-bp direct repeat. The DNA sequence of avrXa10 is nearly identical to avrBs3. We suggest that avrXa7 and avrXa10 are members of an avirulence gene family from xanthomonads that control the elicitation of resistance in mono- and dicotyledonous plants.
Orientation preferences for visual patterns can be conditioned in tethered flies (Drosophila melanogaster) at the flight simulator. In a reversal conditioning procedure using heat as reinforcement, flies can be trained to successively prefer different flight orientations with respect to the patterns. As in many learning paradigms, conditioned responses are highly variable. Although during training most flies reliably avoid the heat and the corresponding flight orientations, in subsequent learning tests without heat some show no consistent preference for the permissive orientations. We have started to investigate the interindividual differences in learning performance and describe here three significant variables: the age of the animals, their experience in the flight simulator prior to the experiment, and the composition of the fly food. Flies learn more reliably at 3-4 days than at 1-2 days of age but learning indices do not increase further in even older flies. Learning is improved if flies are allowed to become familiar with the flight simulator before the start of the conditioning procedure. Most important, poor nutrition causes complete amnesia within three or four generations. The reverse shift from poor to nutritious food restores learning ability with an even longer delay.
Context-dependent preferences in a choice between an upper and a lower visual object of otherwise identical appearance were recorded during stationary flight of the fruitfly, Drosophila melanogaster, in a flight simulator. The test animal was held in a fixed orientation at the center of a wing-beat processor that converts attempted turns into counter-rotations of a surrounding cylindrical panorama. This allowed the fly to maneuver the preferred object into the actual direction of flight. Single flies were trained to avoid a course toward the visual object that had been associated with the aversive odor benzaldehyde (BAL). Conditioned object avoidance was investigated in different treatment groups by collective evaluation of the scores from 80 long-lasting flights (> 1 hr). In addition to a significant cross-modal association, we found a striking long-term effect of transient exposure to BAL both in the embryonic and larval states. The preimaginal experience significantly increased the indifference to BAL in the adult flies. Disturbed vision does not account for this effect: Neither the perception nor the discrimination of the visual objects was significantly impaired in the investigated flies. Disturbed olfaction could explain the present results. Recently, however, preimaginal BAL uptake has been found to interfere directly with the retention of heat-shock-conditioned object avoidance.
A new conditioning procedure, developed for the operant learning paradigm at the flight simulator, leads to stronger learning scores in wild-type flies. This procedure produces mean learning indices up to LI = 0.52. The heat-avoidance behavior acquired during training is very difficult to extinguish during extinction. Memory decays quickly during the first 3 hr after training and still is measurable 48 hr later. Disruption experiments demonstrate that memory can be disrupted by cold anesthesia within the first approximately 20 min after training, whereas KCl- and CXM-feeding regimens abolish memory soon after training and 3 hr later, respectively. These results initially suggest at least three distinct memory phases involved in memory consolidation in Drosophila after operant conditioning.