[Studies on the chemical constituents of the roots of Rosa multiflora Thunb].
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China↗
Biomedical subjects
X Zhao
Publications and source records attributed to X Zhao.
Biochemical pathway of melanotic encapsulation of Brugia malayi in the mosquito, Armigeres subalbatus.
The mosquito, Armigeres subalbatus, is naturally resistant to the filarial worm, Brugia malayi, and microfilariae (mf) penetrating the midgut are killed by melanotic encapsulation reactions in the hemocoel within 48 h following ingestion. This vector-parasite system was used to assess changes in hemolymph tyrosine, tyrosine derivatives, and catecholamine-metabolizing enzyme activities using high pressure liquid chromatography with electrochemical detection (HPLC-ED) during melanotic encapsulation reactions against mf. Tyrosine and dopa were detected in the hemolymph of both control and immune-activated (mf-exposed) mosquitoes, but not dopamine or N-acetyl dopamine (NADA). Tyrosine was significantly increased in immune-activated mosquitoes at 6 and 12 h post blood feeding, but was depleted following intrathoracic inoculation of mf in the absence of a blood meal. Dopa also was elevated in immune-activated mosquitoes at 6, 12, and 24 h post-exposure to mf. There were significant increases in phenol oxidase (PO) and dopa decarboxylase (DDC) activities in immune-activated mosquitoes as compared to controls, and these elevated activities were correlated with changes in tyrosine and dopa levels in the hemolymph. No significant differences in N-acetyl transferase (NAT) and dopachrome conversion enzyme (DCE) activities between control and immune-activated mosquitoes were observed. The possible roles these molecules play in melanotic encapsulation reactions of A. subalbatus against mf are discussed.
Animals↗
Mechanism of rhodopsin phosphorylation.
A key reaction in the inactivation of rhodopsin is its phosphorylation by rhodopsin kinase. In recent years, extensive studies related to rhodopsin kinase function and enzymatic properties were carried out. Rhodopsin kinase is a Ser/Thr protein kinase and a member of the G protein-coupled receptor kinases sub-family (GRKs) which consists of six recently identified members. Photolyzed rhodopsin is phosphorylated by rhodopsin kinase sequentially, with the first phosphate transferred preferentially to Ser-338, and subsequent phosphates transferred to Ser-343 and Thr-336. The binding of arrestin to the receptor, and reduction of the photolyzed chromophore all-trans-retinal to all-trans-retinol limits physiologically significant phosphorylation at no more than three sites (H. Ohguro, R.S. Johnson, L.H. Ericsson, K.A. Walsh and K. Palczewski, Biochemistry, 33 (1994) 1023). A similar phosphorylation reaction is implicated in most, if not all, G protein-coupled receptors during their desensitization.
Amino Acid Sequence↗
Mid-frequency hearing loss in rats following inhalation exposure to trichloroethylene: evidence from reflex modification audiometry.
The present experiments were undertaken to characterize the hearing loss associated with 1,1,2-trichloroethylene (TCE) exposure. Adult male Long-Evans (LE) rats were exposed to TCE via inhalation (whole body) for 6 h/day for 5 days. The concentration-effect function (0-4000 ppm) was determined 3 weeks post-exposure. Animals were tested for auditory thresholds to 4, 8, 16, 24, 32, and 40-kHz tones using reflex modification audiometry. In a separate experiment, the time course of effects was determined by monitoring 16-kHz thresholds prior to, 1 h following each of the 5 exposure days, and 5 days, 1, 2, 4, 8, and 12 weeks post-exposure. At 14 weeks, these same animals were tested for thresholds to 0.5, 1, 2, 4, 8, 16, 24, 32, and 40-kHz tones. Results indicate elevated thresholds (hearing loss) for the 4000 ppm group at 8 and 16 kHz of approximately 18 and 30 dB, respectively. Time-course data demonstrated a rapid onset, a 20-dB loss at 16 kHz after the fifth exposure day, and a 40-dB loss by 2 weeks that persisted up to 14 weeks post-exposure. These data demonstrate an atypical and persistent, mid-frequency hearing loss in rats following inhalation exposure to TCE.
Administration, Inhalation↗
Proinflammatory and antiinflammatory cytokine production during ischemia-reperfusion injury in a case of identical twin living donor liver transplantation using no immunosuppression.
BACKGROUND: Bolus steroids are usually administered prior to graft reperfusion in an attempt to provide protection against ischemia reperfusion injury (IRI). However, the anti-IRI properties of steroids have not been established. Living donor liver transplantation (LDLT) between identical twins provides a unique opportunity to study the natural production of cytokines during transplantation without the confounding influences of the alloimmune response or of immunosuppression in particular steroids. METHODS: A 38-year-old male with hepatitis C virus-related cirrhosis and multiple hepatocellular carcinomas received a hepatic right lobe graft from his identical twin. No immunosuppression was administered, not even intraoperative bolus steroids. IRI was assessed by serum transaminases as well as by proinflammatory interleukin (IL) IL-1beta, tumor necrosis factor (TNF)-alpha, IL-8 cytokines and for potent regenerative/anti-inflammatory (IL-6, IL-10) mediators. RESULTS: Despite no administration of steroids, low peak levels of serum transaminases were observed. Serum IL-6 and IL-10 dramatically and rapidly increased during liver transplantation, namely, 160 and 20 times higher than baseline, respectively. In contrast, IL-1beta and TNF-alpha remained low during and after transplantation and an increase in IL-8 was less obvious. CONCLUSION: Syngeneic LDLT without intraoperative bolus steroids is feasible, yielding no penalty in terms of IRI. A predominance of protective cytokines was observed in the absence of steroids. Thus, the concept that intraoperative administration of steroids is necessary to protect liver transplants from IRI must be revisited.
Adult↗
Characterization of the effects of N-hydroxy-IDPN on the auditory, vestibular, and olfactory systems in rats.
The mechanism of neurotoxicity of 3,3'-iminodipropionitrile (IDPN) has been widely debated, with either the parent compound or putative metabolites implicated in various studies. The N-hydroxylated form of IDPN (HO-IDPN) has been reported to cause the excitation with choreiform and circling (ECC) syndrome in rats at doses approximately one-eighth of that required to cause comparable signs in rats treated with IDPN. Because of the similarity of symptoms induced by HO-IDPN and IDPN, we investigated the effect of HO-IDPN on other aspects of the nervous system affected by IDPN, specifically the auditory, vestibular, and olfactory systems. In addition, ECC symptoms were quantified to replicate the previous findings. HO-IDPN was administered ip in saline for 3 consecutive days to two different cohorts of young adult male Sprague-Dawley rats. The first cohort (60, 80, 100, and 120 mg/kg; n = 2/group, except for the 120 mg/kg group, where n = 1) was used in a dose range-finding study. After making the neurobehavioral assessments, animals were sacrificed for olfactory mucosal histopathology. Based on the outcome of the first study, the second cohort (n = 10/group) received saline or HO-IDPN at 100 mg/kg/day for 3 consecutive days. Two animals from each of these groups were sacrificed for olfactory mucosal histopathology; the remaining animals were tested for neurobehavioral effects 3 weeks after the last dose. Animals in the second cohort lost approximately 8% of their pretreatment body weight. All rats receiving the 100 mg/kg/day dose of HO-IDPN (and the rat receiving 120 mg/kg/day) developed the ECC syndrome and signs of vestibular dysfunction within 4 days after the last dose. HO-IDPN caused a large decrease in the acoustic startle response and markedly elevated auditory thresholds at all frequencies tested. The threshold for the ECC syndrome and olfactory mucosal damage was 100 mg/kg. These studies extend previous findings on the neurotoxicity of HO-IDPN and point to the need for determining whether HO-IDPN is an in vivo metabolite of IDPN.
Animals↗
Body-size corrections for in vivo neutron activation analysis.
Differences in body size and shape can cause large variances in the results of in vivo neutron activation analysis. Preliminary body-size correction data were obtained for the delayed-gamma neutron activation facility (DGNA) at Brookhaven National Laboratory (BNL), based on phantom standards of different sizes, used in combination with computer simulations on the effect of different body sizes.
Body Composition↗
Total body chlorine: calibration of the in vivo neutron activation measurement.
Total body chlorine (TBCI), used to estimate the extracellular space, is measured by delayed-gamma neutron activation (DGNA) using the reaction 37Cl(n, gamma)38Cl, at Brookhaven National Laboratory. During the calibration process, we noticed that different values were obtained when different amounts of Cl were placed in the phantom. This non-linear relationship is due to the thermal neutron flux suppression by the thermal neutron capture reaction 35Cl(n, gamma)36Cl. Monte Carlo simulations confirm the results of phantom measurements showing an inverse relationship between the Cl content in the phantom and the gamma-ray yield per gram Cl. Thus, it is important to calibrate the DGNA system for TBCl using phantom standards containing an amount of Cl close to that expected in the individual undergoing measurement.
Body Composition↗
Molecular cloning and localization of rhodopsin kinase in the mammalian pineal.
Several retinal photoreceptor proteins involved in phototransduction have also been found in the mammalian pineal. This study demonstrates that rat and human pineals express protein kinases that are identical to the corresponding rod photoreceptor rhodopsin kinases. The deduced amino acid sequence of rat and human rhodopsin kinases have 84% sequence similarity to the earlier reported sequence of the bovine retinal enzyme, with complete conservation of the topological regions containing the position of the catalytic domain and sites of posttranslational modifications. Rat pineal also expresses rod opsin and putative blue cone opsin. Using immunocytochemistry, rod opsin and rhodopsin kinase were found to be co-localized in pinealocytes in the human tissue. These data demonstrate that the mammalian pineal contains light-sensitive opsins and a kinase involved in their inactivation. These findings correlate with an earlier report that neonatal rats show extraretinal light sensitivity, and suggest that a functional photoreceptive system may be present in the adult mammalian pineal.
Adult↗
Comparison of vitamin C bioavailability after multiple or single oral dosing of different formulations in sheep.
The purpose of this study was to compare the bioavailability of either multiple or single oral supplementation of different formulations of vitamin C and intra-duodenal supplementation of one form of vitamin C in sheep. Formulations used in the study were (1) ascorbic acid fine powder (AA); (2) ascorbic acid coated with ethyl cellulose (EC); (3) Rovimix STAY-C (SC); (4) sodium ascorbate (SA); (5) Rovimix C (RC). The bioavailability of vitamin C formulations was assessed by the changes in plasma ascorbic acid concentrations, area under the curve (AUC) and area under the curve above its basal concentration (AUCabove) values. There was no effect of single oral supplementation on bioavailability of vitamin C. Multiple dosing over a period of 28 days of oral supplementation of all five formulations resulted in higher AUCabove values. Furthermore, multiple oral supplementation of RC increased plasma concentrations of ascorbic acids and AUC values. Single intra-duodenal supplementation of ascorbic acid resulted in significantly higher AUC when compared with oral supplementation of the same vitamin C.
Administration, Oral↗
Kinetic modeling of bioavailability for sorbed-phase 2,4-dichlorophenoxyacetic acid.
The degradation rate of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in silica-slurry systems to evaluate the bioavailability of sorbed-phase contaminant. After the silica particles were saturated with 2,4-D, the system was inoculated with the 2,4-D-degrading microorganism Flavorbacterium sp. strain FB4. The disappearance rate of 2,4-D was found to be greater than the rate predicted based upon liquid-phase 2,4-D concentrations. A kinetic formulation, termed the enhanced bioavailability model, was developed to describe the desorption and biodegradation processes in this batch system. The approach assumes that 2,4-D resides in both the liquid and solid phases and degradation occurs via both suspended and attached biomass. All biomass can degrade liquid-phase 2,4-D at one rate, while only attached biomass can degrade sorbed 2,4-D at another rate. An enhanced transformation factor (Ef) was introduced to express the increased biodegradation rate over that expected from the liquid phase only. This approach was able to account for the increased degradation rates observed experimentally. The results provide evidence that desorption to the bulk solution is not prerequisite to degradation, and that sorbed substrate may be available for degradation.
2,4-Dichlorophenoxyacetic Acid↗
The evolution of hantaviruses.
Hantaviruses exist in most regions of the world. The many different strains identified thus far have widely divergent roles in human disease and infect a wide range of rodent hosts. The sequence data available for the genomes of these viruses allows us to study indirectly the evolutionary patterns of the hantaviruses. In this paper, we describe relationships among the M genomic segments of hantaviruses, and attempt to relate these to the evolutionary relationships of the virus' rodent hosts.
Animals↗
Lipid peroxidation is associated with the inhibitory action of all-trans-retinoic acid on mammary cell transformation.
BACKGROUND: Retinoids are effective in reducing transformation of various cell types; however the role of lipid peroxidation has not been studied in this regard. MATERIALS AND METHODS: Retinoic acid (RA) and retinol were tested on several SV-40 large-T-antigen transformed bovine mammary fibroblast (MFB) lines that form foci on plastic with long-term culture. RESULTS: Dose response studies revealed that RA at 10(-6) M was the most potent dose in delaying the onset of foci formation and reducing total foci number. RA was always more effective than retinol. Addition of RA (10(-6) M) to MFB cells increased lipid peroxide (LPO) concentrations by approximately three-fold relative to untreated MFB cells or to RA or control treated normal mammary fibroblasts. The lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), acted synergistically with RA to increase LPO and cell death in MFB cells. The combination of the cyclooxygenase inhibitor, indomethacin, at 10(-4) M with 10(-6) M RA lowered MFB fibroblast cell numbers when compared to fibroblasts cultured singly with either RA or indomethacin. CONCLUSIONS: These data indicate that an increase in lipid peroxidation occurs specifically in tumor cells treated with RA and this may play a role in RA-mediated suppression of cellular transformation in the mammary gland. Additionally, eicosanoid inhibitors may have an additive or synergistic effect with RA on the inhibition of mammary tumor cell transformation and proliferation.
Animals↗