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2.
B F BuSha B G Judd H L Manning P M Simon B C Searle J A Daubenspeck J C Leiter 《Journal of applied physiology》2001,90(6):2330-2340
Evidence of the Hering-Breuer reflex has been found in humans during anesthesia and sleep but not during wakefulness. Cortical influences, present during wakefulness, may mask the effects of this reflex in awake humans. We hypothesized that, if lung volume were increased in awake subjects unaware of the stimulus, vagal feedback would modulate breathing on a breath-to-breath basis. To test this hypothesis, we employed proportional assist ventilation in a pseudorandom sequence to unload the respiratory system above and below the perceptual threshold in 17 normal subjects. Tidal volume, integrated respiratory muscle pressure per breath, and inspiratory time were recorded. Both sub- and suprathreshold stimulation evoked a significant increase in tidal volume and inspiratory flow rate, but a significant decrease in inspiratory time was present only during the application of a subthreshold stimulus. We conclude that vagal feedback modulates respiratory timing on a breath-by-breath basis in awake humans, as long as there is no awareness of the stimulus. 相似文献
3.
Brett F BuSha Martha H Stella Harold L Manning J C Leiter 《Journal of applied physiology》2002,93(3):903-910
Imperceptible levels of proportional assist ventilation applied throughout inspiration reduced inspiratory time (TI) in awake humans. More recently, the reduction in TI was associated with flow assist, but flow assist also reaches a maximum value early during inspiration. To test the separate effects of flow assist and timing of assist, we applied a pseudorandom binary sequence of flow-assisted breaths during early, late, or throughout inspiration in eight normal subjects. We hypothesized that imperceptible flow assist would shorten TI most effectively when applied during early inspiration. Tidal volume, integrated respiratory muscle pressure per breath, TI, and TE were recorded. All stimuli (early, late, or flow assist applied throughout inspiration) resulted in a significant increase in inspiratory flow; however, only when the flow assist was applied during early inspiration was there a significant reduction in TI and the integrated respiratory muscle pressure per breath. These results provide further evidence that vagal feedback modulates breathing on a breath-by-breath basis in conscious humans within a physiological range of breath sizes. 相似文献
4.
E. R. Heise D. J. Cook B. S. Schepart C. H. Manning M. R. McMahan M. Chedid C. A. Keever 《Genetica》1987,73(1-2):53-68
The major histocompatibility complex (MHC) encodes cell surface glycoproteins that function in self-nonself recognition and in allograft rejection. Among primates, the MHC has been well defined only in the human; in the chimpanzee and in two species of macaque monkeys the MHC is less well characterized. Serologic, biochemical and genetic evidence indicates that the basic organization of the MHC linkage group has been phylogenetically conserved. However, the number of genes and their linear relationship on the chromosomes differ between species. Class I MHC loci encode molecules that are the most polymorphic genes known. These molecules are ubiquitous in their tissue distribution and typically are recognized together with nominal antigens by cytotoxic lymphocytes. Class II MHC loci constitute a smaller family of serotypes serving as restricting elements for regulatory T lymphocytes. The distribution of class II antigens is limited mainly to cell types serving immune functions, and their expression is subject to up and down modulation. Class III loci code for components C2, C4 and Factor B (Bf) of the complement system.Interspecies differences in the extent of polymorphism occur, but the significance of this finding in relation to fitness and natural selection is unclear. Detailed information on the structure and regulation of MHC gene expression will be required to understand fully the biologic role of the MHC and the evolutionary relationships between species. Meanwhile, MHC testing has numerous applications to biomedical research, especially in preclinical tissue and organ transplantation studies, the study of disease mechanisms, parentage determination and breeding colony management. In this review, the current status of MHC definition in nonhuman primates will be summarized. Special emphasis is placed on the CyLA system of M. fascicularis which is a major focus in our laboratory. A highly polymorphic cynomolgus MHC has been partially characterized and consists of at least 14 A locus, 11 B locus, 7 C locus class I allelic specificities, 9 Ia-like class II antigens and 6 Bf (class III) variants. 相似文献
5.
Properties of carboxymethylated cross-linked hemoglobin A 总被引:2,自引:0,他引:2
The selective carboxymethylation of the N-terminal amino groups of hemoglobin A with glyoxylic acid and sodium cyanoborohydride has been studied as a function of the state of ligation of hemoglobin. The N-terminal residues have been established as the primary sites of reaction by peptide mapping of the tryptic digest of each chain and subsequent amino acid analysis of the modified peptides. With oxyhemoglobin, the desired derivatives with a carboxymethyl group at the N-terminal of either or both chains amounted to 55% [Di Donato, A., Fantl, W. J., Acharya, A. S., & Manning, J. M. (1983) J. Biol. Chem. 258, 11890-11895]. In the present study it is shown that with deoxyhemoglobin the amount of the desired derivative is increased to 75%. The oxygen equilibrium curve of hemoglobin A carboxymethylated on its four N-terminal residues [0.5 mM as tetramer in 50 mM [bis(2-hydroxyethyl)amino]tris(hydroxymethyl)methane (Bis-Tris), pH 7.5, 37 degrees C] had a P50 value of 30 mmHg (Hill coefficient n = 2.8, alkaline Bohr value = 0.4) compared to a P50 of 9 mmHg for unmodified hemoglobin under the same conditions (n = 2.5, alkaline Bohr value = 0.5). In carboxymethylated oxyhemoglobin A, cross-linked with the mild agent glycolaldehyde for 3.5 h, there was 85% of Mr 64,000 species and 15% of Mr 128,000 or higher species. For the former, the extent of cross-linking between two subunits was 19%. For the latter, there was 29% of two cross-linked subunits and 13% of three cross-linked subunits. Termination of cross-linking, which may be desirable in some circumstances, can be successfully achieved with isonicotinic acid hydrazide.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
Inhibition of adhesion of viridans streptococci to fibronectin-coated hydroxyapatite beads by lipoteichoic acid 总被引:1,自引:0,他引:1
Fibronectin-coated hydroxyapatite (FnHA) beads were used in a model adhesion assay to isolate the lipoteichoic acid (LTA) mediated adhesion of oral streptococci. Representative strains of the commonly isolated viridans streptococci were incubated with FnHA beads in the presence and absence of exogenous LTA. The LTA inhibited the adhesion of all strains to a greater or lesser extent, but only a very few strains were inhibited by more than 90%. Strains of Streptococcus sanguis Type II and Streptococcus mitis which synthesize an amphiphile other than LTA were also inhibited. The findings provided circumstantial evidence for the involvement of LTA in the adhesion of this group of oral bacteria. 相似文献
7.
R M Kessler M S Ansari D E Schmidt T de Paulis J A Clanton R Innis M al-Tikriti R G Manning D Gillespie 《Life sciences》1991,49(8):617-628
Epidepride, (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-iodo-2,3-dimethoxybenzamide+ ++, the iodine analogue of isoremoxipride (FLB 457), was found to be a very potent dopamine D2 receptor antagonist. Optimal in vitro binding required incubation at 25 degrees C for 4 h at pH 7.4 in a buffer containing 120 mM NaCl, 5 mM KCl, 2 mM CaCl2 and 1 mM MgCl2. Scatchard analysis of in vitro binding to striatal, medial frontal cortical, hippocampal and cerebellar membranes revealed a KD of 24 pM in all regions, with Bmax's of 36.7, 1.04, 0.85, and 0.37 pmol/g tissue, respectively. The Hill coefficients ranged from 0.91-1.00 in all four regions. The IC50's for inhibition of [125I]epidepride binding to striatal, medial frontal cortical, and hippocampal membranes for SCH 23390, SKF 83566, serotonin, ketanserin, mianserin, naloxone, QNB, prasozin, clonidine, alprenolol, and norepinephrine ranged from 1 microM to greater than 10 microM. Partial displacement of [125I]epidepride by nanomolar concentrations of clonidine was noted in the frontal cortex and hippocampus, but not in the striatum. Scatchard analysis of epidepride binding to alpha 2 noradrenergic receptors in the frontal cortex and hippocampus revealed an apparent KD of 9 nM. At an epidepride concentration equal to the KD for the D2 receptor, i.e. 25 pM, no striatal alpha 2 binding was seen and only 7% of the specific epidepride binding in the cortex or hippocampus was due to binding at the alpha 2 site. Correlation of inhibition of [3H]spiperone and [125I]epidepride binding to striatal membranes by a variety of D2 ligands revealed a correlation coefficient of 0.99, indicating that epidepride labels a D2 site. In vitro autoradiography revealed high densities of receptor binding in layers V and VI of prefrontal and cingulate cortices as well as in striatum. In vivo rat brain uptake revealed a hippocampal:cerebellar and frontal cortical:cerebellar ratio of 2.2:1 which fell to 1.1:1 following haloperidol pretreatment. These properties suggest that [125I]epidepride is a superior radioligand for the in vitro and in vivo study of striatal and extrastriatal dopamine D2 receptors. 相似文献
8.
茧蜂亚科已知有123个属(Quicke,1987),其中窄腹茧蜂属Angustibracon Quicke是Quicke(1987)根据分布在印度的1个种Bracon leptogaster Cameron重新组合为1个新属而建立,迄今已定名种仅此1种。我们整理广西茧蜂标本时,鉴定出该属1新种。这是本属种类在我国分布的首次报道,现将该属属征和新种形态记述如下。新种模式标本存湖南农学院昆虫标本室。 相似文献
9.
B W Manning W L Campbell W Franklin K B Delclos C E Cerniglia 《Applied microbiology》1988,54(1):197-203
Since bacterial nitroreduction may play a critical role in the activation of nitropolycyclic aromatic hydrocarbons, we have used batch and semicontinuous culture systems to determine the ability of intestinal microflora to metabolize the carcinogen 6-nitrochrysene (6-NC). 6-NC was metabolized by the intestinal microflora present in the semicontinuous culture system to 6-aminochrysene (6-AC), N-formyl-6-aminochrysene (6-FAC), and 6-nitrosochrysene (6-NOC). These metabolites were isolated and identified by high-performance liquid chromatography, mass spectrometry, and UV-visible spectrophotometry and compared with authentic compounds. Almost all of the 6-NC was metabolized after 10 days. Nitroreduction of 6-NC to 6-AC was rapid; the 6-AC concentration reached a maximum at 48 h. The ratio of the formation of 6-AC to 6-FAC to 6-NOC at 48 h was 93.4:6.3:0.3. Interestingly, compared with results in the semicontinuous culture system, the only metabolite detected in the batch studies was 6-AC. The rate of nitroreduction differed among human, rat, and mouse intestinal microflora, with human intestinal microflora metabolizing 6-NC to the greatest extent. Since 6-AC has been shown to be carcinogenic in mice and since nitroso derivatives of other nitropolycyclic aromatic hydrocarbons are biologically active, our results suggest that the intestinal microflora has the enzymatic capacity to generate genotoxic compounds and may play an important role in the carcinogenicity of 6-NC. 相似文献
10.
Plasmid profile analysis of a salmonellosis outbreak and identification of a restriction and modification system. 总被引:1,自引:1,他引:0
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After an outbreak of salmonellosis in humans caused by Salmonella typhimurium bacteriophage type 135, 62 isolates from human, animal, and water sources were retained for further analysis. Most of the isolates (92%) could be placed in one of five plasmid pattern groups, with a majority containing a common 60-kilobase plasmid and a smaller 3.8-kilobase-pair plasmid. This small plasmid, pIMVS1, was labeled with [32P]phosphate and used as a probe in subsequent colony and Southern hybridization studies. We concluded that pIMVS1 from isolates obtained from humans was genetically different from plasmids of a similar size found in isolates from chickens. Studies to characterize pIMVS1 were undertaken to determine if it codes for known virulence factors. It did not appear to be associated with the formation of attachment pili or major outer membrane proteins. By using transposon mutagenesis techniques, Tn3(Apr) was inserted into pIMVS1, and the existence of a restriction and modification system was deduced. 相似文献