Kinetics for glutamine-synthetase inhibition by phosphinothricin and measurement of other enzyme activities in situ in isolated asparagus cells using a freeze-thaw technique

Planta ◽  
1984 ◽  
Vol 161 (5) ◽  
pp. 470-474 ◽  
Author(s):  
Andrea R. Fraser ◽  
Stuart M. Ridley
Keyword(s):  
Glutamine Synthetase ◽  
Enzyme Activities ◽  
Freeze Thaw

scholarly journals Enzymology and Ultrastructure of the in situ Pellicle in Caries-Active and Caries-Inactive Patients

2017 ◽  
Vol 51 (2) ◽  
pp. 109-118 ◽  
Author(s):  
Jasmin Kirsch ◽  
Christian Hannig ◽  
Sandra Pötschke ◽  
Sabine Basche ◽  
William H. Bowen ◽  
...  
Keyword(s):  
Exposure Time ◽  
Enzyme Activities ◽  
Fluorescence Labeling ◽  
Oral Exposure ◽  
Pellicle Formation ◽  
Caries Activity ◽  
Transmission Electron ◽  
High Uniformity ◽  
The Impact

Aim: The present study aimed to evaluate the impact of caries activity on the key enzymes and the ultrastructure of the in situ pellicle. Methods: Pellicle formation was performed on bovine enamel slabs. Intraoral exposure (3, 30, and 120 min) was accomplished by 14 caries-active (DMFS: 22.7 ± 12.1) and 13 caries-inactive (DMFS: 1.5 ± 1.8) individuals. The enzyme activities (lysozyme, peroxidase, α-amylase, glycosyltransferase [GTF]) in the in situ pellicle and resting saliva of all participants were analyzed directly after oral exposure. In addition, a simultaneous visualization of these enzymes, extracellular glucans, and adherent bacteria was carried out. Fluorescent patterns were analyzed with fluorescence labeling and 4′,6-diamidino-2-phenylindole/concanavalin A staining. In addition, the distribution of GTF B, C, and D and the ultrastructure of the pellicle were examined by gold immunolabeling and transmission electron microscopy with selected samples. Results: Enzyme activities of amylase, peroxidase, lysozyme, and GTF were detected on all enamel slabs in an active conformation. Neither exposure time nor caries activity had an impact on the enzyme activities. Gold immunolabeling indicated that the pellicle of caries-active subjects tends to more GTF D molecules. The pellicles of caries-inactive and -active individuals revealed a similar ultrastructural pattern. Conclusion: The enzyme activities as well as the pellicle's ultrastructure are of high similarity in caries-active and -inactive subjects. Thereby, oral exposure time has no significant influence. This reflects a high uniformity during the initial phase of bioadhesion (3-120 min) concerning enzymatic functions. However, there is a tendency towards more GTF D in caries-active individuals.

Extrinsic Cell Infiltration and Revascularization Accelerate Mechanical Deterioration of the Patellar Tendon After Fibroblast Necrosis

2000 ◽  
Vol 122 (6) ◽  
pp. 594-599 ◽  
Author(s):  
Harukazu Tohyama ◽  
Kazunori Yasuda
Keyword(s):  
Mechanical Properties ◽  
Patellar Tendon ◽  
Cell Infiltration ◽  
Culture Study ◽  
Cell Culture Study ◽  
Group Iii ◽  
Freeze Thaw ◽  
Group I ◽  
Group Ii

This study was performed to determine the contribution of extrinsic cell infiltration and revascularization into the patellar tendon in alteration of the mechanical properties of the patellar tendon after intrinsic fibroblast necrosis using 77 rabbits. In Group I, after the patellar tendon underwent the in situ freeze-thaw treatment, a wrapping treatment was performed to inhibit any extrinsic cell infiltration into the tendon. In Group II, the patellar tendon underwent the freeze-thaw treatment without any of the wrapping treatment. In Group III, the patellar tendon underwent the same wrapping treatment but without any freeze-thaw treatment. The cell culture study demonstrated that the in situ freeze-thaw treatment killed from 97 to 100 percent of the cells in the patellar tendon. Histologically, no cells were found in the midsubstance of the patellar tendon in Group I at 1, 3, and 6 weeks. In Group II, a number of cells and some vessels were found scattered in the tendon at 3 and 6 weeks. Mechanically, the elastic modulus and the tensile strength of the patellar tendon of Group II were significantly lower than those of Groups I and III at 3 and 6 weeks. These facts suggest that extrinsic cell infiltration and revascularization from the surrounding tissues accelerate the deterioration of the mechanical properties of the patellar tendon matrix after intrinsic fibroblast necrosis. [S0148-0731(00)00506-9]

Effects of freeze–thaw and softening on a natural clay at low stresses

1985 ◽  
Vol 22 (1) ◽  
pp. 69-78 ◽  
Author(s):  
J. Graham ◽  
V. C. S. Au
Keyword(s):  
Pore Water ◽  
Compacted Clay ◽  
Lake Agassiz ◽  
Overburden Pressure ◽  
Freeze Thaw ◽  
Weathering Processes ◽  
Preconsolidation Pressure ◽  
Pore Water Pressures ◽  
Access To Water

Weathering processes such as softening and freeze–thaw cycling affect the properties of clays. Care must therefore be taken when selecting strength and compressibility parameters for analysis of natural slopes, compacted clay embankments, and trench excavations in which significant proportions of the cross section can be affected by climatic weathering.Samples of plastic Lake Agassiz clay from Winnipeg were consolidated anisotropically in the laboratory to axial stresses less than or equal to the in situ effective overburden pressure. They were therefore all overconsolidated with respect to the field preconsolidation pressure. The samples were then loaded under drained or undrained conditions along steeply rising stress paths in p′, q stress space. One group of samples was tested immediately to identify the "undisturbed" behavior, a second group was subjected to freeze–thaw cycles, and a third group allowed to swell freely before testing.The freeze–thaw cycling produced increased compressibility and pore-water pressures, and reduced strengths at low stresses compared with the behavior of undisturbed clay. Freezing also caused the development of a clearly defined fissure structure. Softening at low stresses with access to water produced less marked effects. Key words: clay, undisturbed, freeze–thaw, softening, strength, yielding, pore-water pressures.

scholarly journals Association of Cellulytic Enzyme Activities in Eucalyptus Mulches with Biological Control of Phytophthora cinnamomi

2001 ◽  
Vol 91 (9) ◽  
pp. 847-855 ◽  
Author(s):  
A. J. Downer ◽  
J. A. Menge ◽  
E. Pond
Keyword(s):  
Microbial Activity ◽  
Enzyme Activities ◽  
Phytophthora Cinnamomi ◽  
Soil Depth ◽  
Soil Layers ◽  
Soil P ◽  
Fungal Populations ◽  
Hydrolysis Of ◽  
Vertical Transect

A series of samples were taken from mulched and unmulched trees starting at the surface of mulch or soil to a 15 cm soil depth, forming a vertical transect. Saprophytic fungi isolated from the soil samples on rose bengal medium and surveyed visually were most abundant in mulches and at the interface of mulch and soil (P < 0.05). Microbial activity as assayed by the hydrolysis of fluorescein diacetate was significantly greater in mulch layers than in soils. Cellulase and laminarinase enzyme activities were greatest in upper mulch layers and rapidly decreased in soil layers (P < 0.05). Enzyme activities against Phytophthora cinnamomi cell walls were significantly greater in mulch than in soil layers. When Phytophthora cinnamomi was incubated in situ at the various transect depths, it was most frequently lysed at the interface between soil and mulch (P < 0.001). Roots that grew in mulch layers were significantly less infected with Phytophthora cinnamomi than roots formed in soil layers. In mulched soil, roots were commonly formed at the mulch-soil interface where Phytophthora populations were reduced, whereas roots in unmulched soil were numerous at the 7.5 cm depth where Phytophthora cinnamomi was prevalent. Enzyme activities were significantly and positively correlated with each other, microbial activity, and saprophytic fungal populations, but significantly and negatively correlated with Phytophthora recovery.

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