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B Gao

Publications and source records attributed to B Gao.

At least 127 records · Page 7Linked to original sources
PubMed1995

Identification of distinct GABAA-receptor subtypes in cholinergic and parvalbumin-positive neurons of the rat and marmoset medial septum-diagonal band complex.

GABAA-receptor heterogeneity is based on a multiplicity of subunits (alpha 1-6, beta 1-4, gamma 1-4, delta, rho 1-2) encoded by distinct genes. Flexibility in GABAergic signal transduction and allosteric modulation is expected to arise from the differential assembly of subunits into receptor subtypes. The aim of the present study was to investigate the potential diversity of receptor subtypes expressed by defined neuron populations, as identified by their neurotransmitter phenotype. To this end we have determined immunohistochemically the subunit repertoire of cholinergic and GABAergic neurons in the basal forebrain of rat and marmoset monkey, focusing on the medial septum-diagonal band complex. Co-localization of the GABAA-receptor subunits alpha 1, alpha 3, beta 2, beta 3, and gamma 2 with markers of cholinergic and GABAergic neurons (choline acetyltransferase and parvalbumin, respectively) was assessed by double- and triple immunofluorescence staining. The results reveal that cholinergic neurons in the rat basal forebrain are typically characterized by the subunit combination alpha 3/beta 3/gamma 2, whereas most of the parvalbumin-positive GABAergic neurons express either the subunit combination alpha 1/beta 2/gamma 2 or the combination alpha 1/alpha 3/beta 2/gamma 2. A similar pattern was observed in marmoset monkey, with GABAA-receptors containing the alpha 1-subunit being associated with parvalbumin-positive cells, but never with cholinergic neurons. Thus, the expression of distinct subunit repertoires by cholinergic and GABAergic neurons points to a functional specialization which is conserved across species. These subunit combinations are likely to correspond to different receptor subtypes, and may reflect the engagement of cholinergic and GABAergic neurons in distinct neuronal circuits in the basal forebrain.

Animals↗
PubMed1995

Tests for possible effects of selection by domestic pyrethroids for resistance in culicine and anopheline mosquitoes in Sichuan and Hubei, China.

Resistance tests, by conventional methods and by observing the time for knockdown, showed no evidence for any build up of resistance to deltamethrin in malaria vectors from areas where millions of bednets have been treated with this compound annually for up to 7 years. However, a strain of Culex quinquefasciatus which had been bred in a factory in which volatile pyrethroids are handled had developed unequivocal resistance to deltamethrin. Observation of the time for knockdown gave clearer discrimination between resistant and susceptible strains than did observation of percentage mortality after a standard exposure time.

Animals↗
PubMed1995

[Protective action of Lycium barbarum L. (LbL) and betaine on lipid peroxidation of erythrocyte membrane induced by H2O2].

H2O2 was used to induce lipid peroxidation of RBC membrane in rats to observe the protective action of different ingredients of LbL and betaine on the membrane. The result shows these ingredients cna inhibit the lipid peroxidation of RBC membrane in the following order of antioxidizing power: Fructus Lycii.LbL.dry(FL/LbL.dry) > Polysaccharide FL/LbL > Residue FL/LbL > betaine.

Animals↗
PubMed1995

[Studies on the deltamethrin-medicated bath of domestic dogs for interrupting visceral leishmaniasis transmission].

In a previous paper, it was reported that deltamethrin-medicated bath of domestic dogs had a strong killing effect against Ph. chinensis, and could also inhibit its blood sucking ability or cause its death shortly after blood sucking. The effect could last for 30 days to 114 days, and mostly for 2 months in the local area. Based on our previous study, three villages (Yongle, Yongfeng, Anle) and a town (Chengguan) were selected from the mountainous region with high incidence of visceral leishmaniasis in Nanping County, northern Sichuan for carrying out an extensive experiment of medicated bathing of domestic dogs, where there were 13 new infected cases in the year of 1991 before the experiment. During the sandfly season in 1992, two rounds of medicated bathing of dogs were conducted, the drug concentration used was 50 ppm. From September 1992 to August 1993, the number of new infected cases was 11 in the above mentioned three villages and a town. Another two rounds of medicated bathing of dogs had been conducted during the sandfly season in 1993. The results show that there was no new infection from September 1993 to October 1994 in the three villages and a town, indicating that through two years' consecutive extensive medicated bathing of dogs in the endemic areas, canine visceral leishmaniasis transmission had been significantly interrupted. The authors consider that in the mountainous region of southern Gansu and northern Sichuan where it has been difficult to treat dogs, it might be more practical to use deltamethrin bathing of dogs for interrupting the transmission of canine visceral leishmaniasis.

Animals↗
PubMed1995

Analysis of heterogeneity of gene products (interferon) expressed in yeast.

FPLC, SDS-PAGE and Western blot techniques are used to analyse the heterogeneity of interferon alpha A (IFN-alpha A) expressed in yeast. The heterogeneity consists of (i) the presence of IFN polymer, (ii) partial processing of signal leader peptide and (iii) internal degradation. The reasons for heterogeneity of gene products in expression system of yeast are analysed. The methods of avoiding heterogeneity, such as depolymerization, adding inhibitors of protease to the culture supernatant, the oligonucleotide-directed deletion mutagenesis and improvements of fermentation, are discussed.

Gene Expression↗
PubMed1995

[Studies on the bionomics of Phlebotomus chinensis in mountain cave and its relation to control in northern Sichuan].

After a survey of the gonotrophic cycle of 5147 female Phlebotomus chinensis collected from the caves in the mountain area 1500 m above sea level in Nanping County, Sichuan Province where this sandfly was proved to be the typical predominant wild species living mostly in the wild cave at a very high density, a large cave was sprayed with alphamethrin at a dosage of 50 mg/m2 in July, 1993. As a result, the sandfly density dropped to zero spanning over a period of two peak seasons. The authors consider that the residual effect of alphamethrin as long enough to suppress sandfly density in the cave for at least two years, and stress that the spray is a favourable measure in all the year round in reducing the sandfly population density and preventing visceral leishmaniasis.

Animals↗
PubMed1994

Transcription of the rat alpha 1B adrenergic receptor gene in liver is controlled by three promoters.

The proximal 5'-flanking region of the rat alpha 1B adrenergic receptor (alpha 1BAR) gene contains discrete transcription start points (tsp) utilized in liver, located at -54, -57 (tsp1), and -443 base pairs (tsp2) upstream from the translation start codon (Gao, B., and Kunos, G. (1993) Gene (Amst.) 131, 243-247). Primer extension analyses using 5' upstream primers now identify an additional cluster of tsp between -1035 and -1340 base pairs (tsp3). Northern blots of rat liver mRNA reveal three alpha 1BAR mRNAs of 2.3, 2.7, and 3.3 kilobases in length. Transient transfections of putative promoter/pCAT constructs document the existence of three promoters, P1 (-127, -49), P2- (-813, -432), and P3 (-1363, -1107), which direct transcription from tsp1, tsp2, and tsp3, respectively. P1 contains no recognition sequences for known transcription factors. P2 is (G + C)-rich, lacks a TATA box, and contains a cAMP response element, GC, CACC, and GCAAT boxes, and binding sites for nuclear factor I. P3 contains a putative TATATA and CCAAT box and is flanked by recognition sites for the liver-specific CCAAT/enhancer binding protein and hepatocyte nuclear factor 5. These findings indicate that heterogeneity of alpha 1BAR mRNA in liver is related to transcription of the gene by three distinct promoters. Differential control of these promoters may underlie the well documented developmental and tissue-specific regulation of the alpha 1BAR.

Animals↗
PubMed1994

Selective allocation of GABAA receptors containing the alpha 1 subunit to neurochemically distinct subpopulations of rat hippocampal interneurons.

The identification of a large variety of GABAA receptor subunits by molecular cloning suggests the existence of multiple receptor subtypes differing in localization and functional properties. In the present study we analysed immunohistochemically the cellular distribution of GABAA receptors containing the alpha 1 subunit in the rat hippocampus with a subunit-specific antiserum. Prominent staining of numerous interneurons was evident in Ammon's horn and the dentate gyrus, which contrasted with moderate and diffuse immunoreactivity in the dendritic layers of pyramidal and granule cells. Double immunofluorescence staining with antibodies to GABA revealed that a subset of GABAergic neurons in the hippocampus were immunoreactive for the alpha 1 subunit. To determine whether these cells represent distinct subpopulations of interneurons, we analysed the co-localization of the GABAA receptor alpha 1 subunit with selective markers of hippocampal interneurons (selected calcium-binding proteins and neuropeptides). In both Ammon's horn and the dentate gyrus, all parvalbumin-positive neurons and 50% of calretinin-positive neurons were double-labelled, whereas interneurons containing calbindin-D28k were devoid of alpha 1 subunit staining. Similarly, most neurons positive for neuropeptide Y and a subset of somatostatin-positive cells were double-labelled, in contrast to cholecystokinin- and vasoactive intestinal peptide-containing cells, which lacked the alpha 1 subunit staining. These results demonstrate cell-specific expression of GABAA receptors containing the alpha 1 subunit among subsets of hippocampal interneurons, pointing to a pronounced functional specialization of these cells. Furthermore, the prominent expression of GABAA receptors by interneurons suggests that disinhibition may be of major functional relevance in regulating the balance between excitation and inhibition in hippocampal circuits.

Animals↗
PubMed1994

Characterization of nucleotide-free uncoating ATPase and its binding to ATP, ADP, and ATP analogues.

The interactions of the 70-kDa heat-shock proteins (hsp70s) with their protein substrates appear to be regulated by bound nucleotide. Previous work has shown that the nucleotide binding site of the bovine brain uncoating ATPase, a constitutive member of the hsp70 family, crystallographically resembles the nucleotide binding site of actin and, like actin, the uncoating ATPase has a strongly bound ADP which cannot be removed by dialysis or treatment with ethylenediaminetetraacetic acid (EDTA). This suggests that, like the bound nucleotide of actin, it may be required for the enzyme to retain its native structure. In this study, the strongly bound ADP was removed by first replacing it with 5'-adenylyl imidodiphosphate (AMP-PNP) and then removing the bound AMP-PNP by dialysis. Following this treatment, more than 95% of the uncoating ATPase becomes nucleotide-free. The nucleotide-free uncoating ATPase retains its ability to bind and hydrolyze ATP and to uncoat clathrin-coated vesicles, even after 10 days of storage at 4 degrees C. Therefore, in contrast to actin, the bound nucleotide of the uncoating ATPase is not required to prevent denaturation of the enzyme. Using nucleotide-free uncoating ATPase, we were able to accurately measure the dissociation constants of ATP, ADP, and the nucleotide analogues AMP-PNP and 2'-deoxyadenosine 5'-triphosphate (dATP). The dissociation constants of both ATP and ADP are about 10(-8) M, more than 1-2 orders of magnitude stronger than previously reported, while AMP-PNP and dATP bind 2-3 orders of magnitude more weakly than ATP.

Adenosine Diphosphate↗
PubMed1994

Effects of acute and chronic administration of the antidepressants, imipramine, phenelzine and mianserin, on the social behaviour of mice.

Effects of imipramine, phenelzine and mianserin on the behaviour of male CDl mice were examined after a single intraperitoneal injection (imipramine, 15.8 and 63.2 mumol/kg; phenelzine, 1 and 8 mumol/kg); mianserin, 0.12 and 0.48 mumol/kg) and after administration for 12-16 days in the drinking fluid (mean daily intake; imipramine, 15.8 and 63.2 mumol/kg; phenelzine, 1 and 8 mumol/kg; mianserin, 0.12, 0.48 and 1.92 mumol/kg). Behaviour was examined by ethological procedures during 5 min encounters with an untreated partner in a familiar situation, the animal's home cage, and in the more aversive environment of an unfamiliar cage. At 30 min after injection, the higher doses of acutely administered imipramine and mianserin decreased aggressive behaviour in the unfamiliar cage. In the home cage, effects of mianserin were only slight, whereas imipramine reduced social investigation at the larger dose and in both test environments decreased digging. Phenelzine increased social investigation in both environments. After chronic administration, each of the drugs increased social investigation in the neutral cage and home cage at some of the dose levels, indicating potential anxiolytic efficacy. Mianserin showed the additional effect of enhancing digging during tests in the neutral cage, which may correlate with its anxiolytic actions. Phenelzine was the only antidepressant to increase aggression during encounters in the neutral cage after chronic administration. The significance of these findings is discussed.

Aggression↗
PubMed1994

Neutrophil-generated free radicals: possible mechanisms of injury in adult respiratory distress syndrome.

The acute lung injury resulting from adult respiratory distress syndrome (ARDS) is thought to be largely mediated by activated neutrophils. Because activated neutrophils produce the superoxide radical, which is both bacterial and cytotoxic to host cells, this oxygen-derived free radical is likely responsible for at least part of the neutrophil-mediated lung injury. In a rat model of ARDS resulting from intratracheal instillation of interleukin-1, recombinant human manganous superoxide dismutase significantly decreased lung leak. One detrimental action of proteases released by adherent neutrophils may be the degradation of extracellular superoxide dismutase (ECSOD), which normally binds to the heparan sulfate on the surface the endothelium. We found that rabbit ECSOD incubated with either trypsin or activated neutrophils loses affinity for heparin. Furthermore, soluble ECSOD is elevated in the serum of patients with ARDS, consistent with this hypothesis.

Animals↗
PubMed1994

Refined structure of trichosanthin at 1.73 A resolution.

An X-ray reflection data set of the orthorhombic crystal of Trichosanthin (TCS) at 1.73 A resolution had been collected using the area detector. We determined TCS crystal structure by the molecular replacement method using the data of the known alpha-momocharin model and TCS intensities, and then TCS structure refinement at 1.73 A resolution was performed with the restrained least-squares refinement. A final R-factor of 0.186 was obtained with a model obeying standard geometry within 0.013 A in bond lengths and 2.48 degrees in bond angles. The final model contains 133 solvent molecules in the asymmetric unit. This paper gives a detailed description of TCS molecule structure, temperature factors, hydrogen bonds, bound water, the distribution of conserved residues and the interactions between the TCS molecules. The hydrogen bond between the hydroxyl group of conserved residue 14Tyr and O157 plays an important role in maintaining the active site conformation. Conserved residue 160Glu and its conformation at the active site play a key role in the catalytic activity.

Crystallography, X-Ray↗
PubMed1994

Sleep deprivation in the rat at different ambient temperatures: effect on sleep, EEG spectra and brain temperature.

To investigate the relationship between thermoregulation and sleep regulation, rats were sleep-deprived for 3 hours at two different ambient temperatures. Sleep deprivations (SD) were performed at 23 degrees C (SD-23) and at 32 degrees C (SD-32) in the beginning of the 12-h light period in animals chronically implanted with ECoG and EMG electrodes, and with epidural and hypothalamic thermistors. SD-32 enhanced cerebral temperature more than SD-23 at both brain sites. The SD-induced hyperthermia was followed by a fall of brain temperature below baseline. During recovery from either SD procedure, waking was reduced and sleep continuity increased. REM sleep was increased after SD-32. EEG slow-wave activity (spectral power density in the 0.75-4.0 Hz band) exceeded the baseline level in the first 3-h interval of recovery; however, the effects of SD-23 and SD-32 did not differ. In the same time interval, power density in the 1.25-1.5 Hz bin as well as in some bins in the theta and alpha band was higher after SD-32 than after SD-23. The increase in hypothalamic temperature during SD did not correlate with the increase in SWA during recovery. It is concluded that even a brief SD has major repercussions on recovery sleep whereas the extent of cerebral hyperthermia during SD is only a minor factor.

Animals↗
PubMed1993

Isolation and characterization of the gene encoding the rat alpha 1B adrenergic receptor.

Using a rat alpha 1B adrenergic receptor(AR)-encoding cDNA probe, we isolated two genomic clones from a rat liver genomic DNA library. Southern blot analysis and nucleotide sequencing indicate that the rat alpha 1B AR gene has two exons and a single large intron of at least 16 kb. Analysis of the sequence of the 5'-flanking region suggests that this gene has the features of a housekeeping gene: it has neither a TATA box nor a CAAT box, but has multiple transcription start points (tsp), multiple Sp1-binding sites, and a high G + C content. The 5'-flanking region also contains consensus sequences for AP1- and AP2-binding sites, and putative sites for cyclic AMP (CRE), glucocorticoid (GRE), and thyroid responses (TRE). The 3'-flanking region contains a putative polyadenylation signal (ATTAAA) 492 bp downstream from the stop codon. A comparison of the rat alpha 1B AR sequence with that of the recently cloned human alpha 1B AR gene showed that the overall structure of this gene is highly conserved, with some notable differences in the 5'-flanking region.

Animals↗