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1.
James A. Wanner 《American journal of physical anthropology》1977,47(1):99-102
An analysis of the anterior patellar groove of the human femur shows considerable variation in its medial and lateral spects. The groove itself, measured by the angle it encloses, shows considerably less variation than its individual components. The suggested functional relationship between bicondylar angle and lateral elevation of the patellar groove does not obtain for this sample. 相似文献
2.
Control of phoR-dependent bacterial alkaline phosphatase clonal variation by the phoM region. 总被引:14,自引:9,他引:5
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B L Wanner 《Journal of bacteriology》1987,169(2):900-903
phoR mutants with the wild-type Escherichia coli K-12 Var+ phoM region showed clonal variation of bacterial alkaline phosphatase synthesis, whereas mutants with the pho-510 Var- allele did not. The pho-510 mutation is responsible for the phoR mutant constitutive phenotype and probably arose in E. coli K-12 58F+ after X-ray mutagenesis over 40 years ago. I propose that the phoM region controls a change in state of bacterial alkaline phosphatase synthesis, at least in phoR mutants. Four possible molecular mechanisms for how phoM may act are discussed. 相似文献
3.
A technique is described for using standard squash preparations of mitotic and meiotic chromosomes for both light microscopy
and subsequent high-resolution scanning electron microscopy for investigation of the same specimen. Depending on the microscope
and conditions of preparation, a resolution of a few nanometers is routinely possible. Tilting of the specimen provides a
three-dimensional insight into chromosomal structures. Combination of material-dependent signals of backscattered electrons
with the secondary electron image allows an unambiguous localization of surface markers. 相似文献
4.
5.
Bacterial alkaline phosphatase clonal variation in some Escherichia coli K-12 phoR mutant strains. 总被引:10,自引:9,他引:1
B L Wanner 《Journal of bacteriology》1986,168(3):1366-1371
Several phoR alleles (phoR19, phoR20, phoR68, phoR69, phoR70, and phoR78) led to either a bacterial alkaline phosphatase (BAP)-constitutive phenotype or a variable behavior, depending upon the strain tested. Whereas Escherichia coli K10, MC1000, and XPh4 phoR mutants were constitutive, AB1157, BD792, MC4100, and W3110 phoR mutants displayed the metastable character. For the latter strains, constitutive mutants regularly segregated BAP-negative clones which yielded constitutive variants again at a high frequency. Indeed, the pattern of variation observed in BAP-variable phoR strains is phenotypically analogous to phase variation of the H1/H2 flagellum antigen type in Salmonella typhimurium and the molecular switch between the immune and sensitive states in bacteriophage lambda. The metastable behavior was not a general property of BAP-constitutive mutants, since several phosphate-specific transport-phoU mutations led to a constitutive (stable) phenotype regardless of the strain tested. But in phoR phosphate-specific transport-phoU mutants, the metastable character was epistatic (dominant), and such double mutants showed clonal variation in BAP-variable strains. 相似文献
6.
W.M. Abraham S. Lanes A. Wanner J.S. Stevenson E. Codias L.D. Yerger 《Prostaglandins & other lipid mediators》1986,31(3)
Allergic sheep respond to inhaled
antigen with either acute and late bronchial obstructions (dual responders) or only acute bronchoconstriction (acute responders). In this study we tested the hypothesis that one factor which may distinguish between these two populations is the difference in sensitivity to a specific mediator of airway anaphylaxis, leukotriene (LT) D4 (a major component of slow reacting substance of anaphylaxis). We postulated that if the hypothesis was correct than dual responders should demonstrate increased airway responses to inhaled LTD4 and that this increased responsiveness should also be reflected by a more severe response to inhaled antigen. To test this we used animals from both groups with the same degree of non-specific airway responsiveness to carbachol and determined their airway responses to controlled inhlation challenges with synthetic LTD4 and
antigen. Airway responsiveness to carbachol was determined by measuring the change in specific lung resistance (SRL) to increasing concentrations of carbachol aerosol, and then identifying, by linear interpolation, the provocative carbachol concentration which produced a 150% increase (PC150) in SRL. Airway responses to LTD4, and antigen were determined by measuring the percentage change in SRL after a controlled inhlation challenge with either aerosol. Airway responsiveness to carbachol was not different between the two groups. There was, however, a difference (p<0.05) in the airway response to the same dose of LTD4 in the two groups. Dual responders showed a 297±72% increase in SRL as compared to a 90±13% increase in SRL in the acute responders. Dual responders also showed a greater immediate and more prolonged response to antigen than did acute responders. These results suggest that increased responsiveness to LTD4 may be one factor which may distinguish dual responders from acute responders. 相似文献
7.
Allergic bronchoconstriction may be associated with hemodynamic alterations due to changes in respiratory mechanics (or the associated changes in arterial blood gas composition) or the cardiovascular effects of chemical mediators. In an attempt to differentiate between these two possible mechanisms, we obtained measurements of hemodynamics, respiratory mechanics, and O2 consumption (VO2) in nine asymptomatic adult ragweed asthmatics before and after inhalation challenge with either ragweed extract or methacholine. We measured specific airway conductance (sGaw) by body plethysmography, pleural pressure with an esophageal balloon catheter, pulmonary blood flow (Q) and VO2 by a rebreathing technique, and heart rate. For a similar degree of bronchoconstriction after the two types of challenge (mean +/- SD sGaw 0.06 +/- 0.03 and 0.05 +/- 0.02 cmH2O-1 . s-1, P = NS), mean Q increased by 29 and 29%, and mean VO2 by 33 and 37% 15-20 min after ragweed and methacholine, respectively. Since heart rate did not change, there was a concomitant increase in mean stroke volume by 25 and 35%, respectively (P less than 0.05). The respiratory pleural pressure swings during quiet breathing and the rebreathing maneuver and the work of breathing during rebreathing also increased to a similar degree after the two types of challenge. These observations suggest that, if chemical mediators are released into the circulation during antigen-induced bronchoconstriction, their blood concentrations are too low for appreciable cardiovascular effects. The increase in rebreathing cardiac output during allergic and nonallergic bronchoconstriction is probably due to increases in intrathoracic pressure swings and in the work of breathing. 相似文献
8.
Long W. M.; Sprung C. L.; el Fawal H.; Yerger L. D.; Eyre P.; Abraham W. M.; Wanner A. 《Journal of applied physiology》1985,59(1):254-261
The effects of aerosolized 5% histamine (10 breaths) on bronchial artery blood flow (Qbr), airflow resistance (RL), and pulmonary and systemic hemodynamics were studied in mechanically ventilated sheep anesthetized with pentobarbital sodium. Histamine increased mean Qbr and RL to 252 +/- 45 and 337 +/- 53% of base line, respectively. This effect was significantly different from base line for 30 min after challenge. The histamine-induced increase in RL was blocked by pretreatment with the histamine H1 receptor antagonist, chlorpheniramine, whereas the histamine-induced elevation in Qbr was prevented by the H2 antagonist, metiamide. Both responses were blocked only when both antagonists were present. Changes in Qbr were not directly associated with alterations in systemic and pulmonary hemodynamics or arterial blood gas composition. In vitro histamine caused a dose-dependent contraction of ovine bronchial artery strips that was prevented by H1 antagonist. The H2 agonist, impromidine, caused relaxation of precontracted arterial strips and was more potent and efficacious than histamine, whereas H1 agonists failed to elicit a relaxant response. Thus these findings indicate that histamine aerosol induces a vasodilation in the bronchial vascular bed; histamine has a direct effect on Qbr that is independent of alterations in RL, systemic and pulmonary hemodynamics, or arterial blood gas composition; and, histamine-induced bronchoconstriction is mediated predominantly by H1-receptors, whereas increased Qbr is controlled predominantly by H2-receptors, probably located in resistance vessels. This local effect of histamine on Qbr may have important implications in the pathophysiology of bronchial asthma and pulmonary edema. 相似文献
9.
Out of the eight enzymes involved in the biosynthesis of the isoquinoline alkaloid berberine, at least, two enzymes, berberine bridge enzyme and (S)-tetrahydroprotoberberine oxidase, are exclusively located in a vesicle with a specific gravity of =1.14 g·cm–3 as shown by direct enzymatic assay as well as immunoelectrophoresis. Electronmicroscopic examination of the enzyme-containing particulate preparation from Berberis wilsoniae var. subcaulialata cultured cells demonstrated that it is composed mainly of membranous vesicles. The protein composition of this preparation reveals the presence of only about 20 separable proteins, of which two major ones are berberine bridge enzyme and (S)-tetrahydroprotoberberine oxidase. Incubation of these vesicles with the substrate (S)-reticuline in the presence and absence of S-adenosyl-l-methionine leads to the formation of a red product which was identified as dehydroscoulerine. If the cytoplasmic enzyme S-adenosyl-l-methionine:(S)-scoulerine-9-O-methyltransferase is added to the vesicle preparation in the presence of (S)-reticuline and S-adenosyl-l-methionine, not dehydroscoulerine but columbamine, the immediate precursor of berberine is formed. Some of the quaternary alkaloids are located inside the vesicles; fusion of these vesicles leads to vacuoles containing the quaternary alkaloids. These vesicles are the first highly specific and unique compartment serving only alkaloid biosynthesis; they are found in members of four different plant families and in cell cultures as well as in differentiated tissue.Abbreviations BBE
berberine bridge enzyme
- STOX
(S)-tetrahydroprotoberberine oxidase
Dedicated to Professor Karl Decker, Freiburg, on the occasion of his 60th birthday 相似文献
10.
Summary Whole young plants were allowed to fix photosynthetically C14O2 for 12 hours. The absolute amount and the specific activity of trigonelline, caffeine and glucose in developing and adult leaves were subsequently determined during up to five weeks. There is a rapid incorporation of photosynthetically fixed carbon into trigonelline in both developing and adult leaves. The specific activity of caffeine however increases to any extent only in young developing leaves. It can be concluded that both trigonelline and caffeine are synthesized in leaves ofCoffea arabica. Other problems of the metabolism and translocation of the two substances are discussed.
Mit 5 Textabbildungen 相似文献
Mit 5 Textabbildungen 相似文献