Sem Observations in Gastric Mucosa Exposed to Progressive Enzymatic Etching

1980 ◽  
Vol 38 ◽  
pp. 570-571
Author(s):  
C.A.E. Lemmi ◽  
D. Booth ◽  
G.E. Adomian
Keyword(s):  
Gastric Mucosa ◽  
Critical Point ◽  
Proteolytic Activity ◽  
Etching Process ◽  
Cellular Types

In order to enrich populations of homogeneous cellular types we dissociated gastric mucosa by enzymatic techniques. In addition, we used SEM to monitor the progressive etching of the mucosa. Two enzymes were tested: collagenase III with minimum proteolytic activity and Pronase with broader proteolytic effects. The gastric mucosa was exposed to the effect of the enzymes using everted stomach preparations. In this way the digestive action occured progressively from the lumen of the stomach toward the base of the glands. This “etching” process could be monitored conveniently by SEM. After incubation for periods varying from 30 to 210 minutes the tissues were stretched on dental wax, fixed in 2 % glutaralheyde, post-fixed in osmium, dehydrated, critical point dryed and coated with gold. A model MSM-5 “Mini-SEM” was used for observation. Gentle uncurling of the preparation before coating with gold produced fractures which revealed the structure of the gastric glandsin more detail.

Separation of pepsinogen II and pepsinogen III from human urine

1964 ◽  
Vol 206 (5) ◽  
pp. 1106-1110 ◽  
Author(s):  
Max J. Seijffers ◽  
Harry L. Segal ◽  
Leon L. Miller
Keyword(s):  
Gastric Mucosa ◽  
Proteolytic Activity ◽  
Human Urine ◽  
Chromatographic Behavior ◽  
Pepsinogen I ◽  
Qualitative And Quantitative ◽  
Quantitative Correlation ◽  
Diethylaminoethyl Cellulose ◽  
Pepsinogen Ii ◽  
Urine Specimens

Human urine has been fractionated on diethylaminoethyl cellulose to yield two pepsinogens. They have been called pepsinogen II and pepsinogen III on the basis of chromatographic behavior identical to that of fundic mucosal pepsinogens II and III. Pepsinogen I has been found absent from 23 urine specimens of 12 individuals. Results suggest a gross qualitative and quantitative correlation between pepsinogen II-pepsinogen III ratio (in terms of total proteolytic activity) in urine and gastric mucosa.

scholarly journals CRYSTALLINE PEPSIN

1933 ◽  
Vol 16 (4) ◽  
pp. 615-623 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Gastric Mucosa ◽  
Magnesium Sulfate ◽  
Gastric Juice ◽  
Proteolytic Activity ◽  
Optical Activity ◽  
Specific Activity ◽  
Crystalline Form ◽  
High Proteolytic Activity ◽  
Related Proteins

1. A method has been described for isolating a crystalline protein with high proteolytic activity from bovine gastric juice by means of precipitation with magnesium sulfate and fractionation of the precipitate with acetone and magnesium sulfate. 2. The crystalline protein obtained in this way has the same crystalline form, optical activity, and specific activity, as determined by a number of methods, as does the crystalline protein previously isolated from swine gastric mucosa. 3. The solubility of the two preparations, however, is additive so that they are different although very closely related proteins.

scholarly journals The isolation and properties of a non-pepsin proteinase from human gastric mucosa

1978 ◽  
Vol 169 (3) ◽  
pp. 617-624 ◽  
Author(s):  
N B Roberts ◽  
W H Taylor
Keyword(s):  
Bone Marrow ◽  
Gastric Mucosa ◽  
Gastric Adenocarcinoma ◽  
Proteolytic Activity ◽  
Structural Characteristics ◽  
Human Gastric Mucosa ◽  
Cathepsin E ◽  
Activity Curve ◽  
Rabbit Bone ◽  
Ph Range

1. A non-pepsin proteinase, proteinase 2, was successfully isolated free from pepsinogen (by repetitive chromatography on DEAE- and CM-celluloses) from the gastric mucosa of a patient with a duodenal ulcer and the uninvaded mucosa of a patient with a gastric adenocarcinoma. 2. Proteinases 1a and 1b, found in gastric adenocarcinoma, were not found in the gastic mucosa of these patients. 3. Proteinase 2 was shown to have an asymmetrical broad pH-activity curve with a maximum over the pH range 3.0-3.7. 4. Proteolytic activity of proteinase 2 was inhibited by pepstatin; the concentration of pepstatin giving 50% inhibition is of the order of 3nm. 5. Inhibition of proteolytic activity by carbenoxolone and related triterpenoids indicated that at pH 4.0 proteinase 2 possesses structural characteristics relating it to the pepsins and at pH 7.4 to the pepsinogens. 6. The sites of cleavage of the B-chain of oxidized insulin for proteinase 2 at pH 1.7 and pH 3.5 were shown to be similar to those previously established for human pepsin 3 and for the cathepsin E of rabbit bone marrow. 7. The non-pepsin proteinase 2 (cathepsin) of human gastric mucosa has properties more similar to cathepsin E than to the cathepsins D.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

SEM Cold Stage Techniques for the Observation of Vegetative and Floral Apices of Oat (Avena sativa L.) Plants

1977 ◽  
Vol 35 ◽  
pp. 590-591
Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Critical Point ◽  
Avena Sativa ◽  
Substantial Improvement ◽  
Fresh Tissue ◽  
Cold Stage ◽  
Critical Point Drying ◽  
Almost All ◽  
Cell Collapse ◽  
Conductive Paint ◽  
Carbon Based

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.

The Effects of Drying Techniques on Clay-Rich Soil Texture

1974 ◽  
Vol 32 ◽  
pp. 466-467
Author(s):  
T. G. Naymik
Keyword(s):  
Critical Point ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Drying Methods ◽  
Air Drying ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Set Up ◽  
The Relationship ◽  
Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

Preservation of Plant Cell Surfaces For Scanning Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 472-473
Author(s):  
Linda M. Sicko ◽  
Thomas E. Jensen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Filter Paper ◽  
Freeze Drying ◽  
Cell Surfaces ◽  
Air Drying ◽  
Popular Method ◽  
Critical Point Drying ◽  
Scanning Electron

The use of critical point drying is rapidly becoming a popular method of preparing biological samples for scanning electron microscopy. The procedure is rapid, and produces consistent results with a variety of samples. The preservation of surface details is much greater than that of air drying, and the procedure is less complicated than that of freeze drying. This paper will present results comparing conventional air-drying of plant specimens to critical point drying, both of fixed and unfixed material. The preservation of delicate structures which are easily damaged in processing and the use of filter paper as a vehicle for drying will be discussed.

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