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Z Lojda

Publications and source records attributed to Z Lojda.

At least 91 records · Page 5Linked to original sources
PubMed1988

Dipeptidyl peptidases of human lymphocytes.

In human lymphocytes three dipeptidyl peptidases were discovered in our laboratory. For a correct demonstration of activities of these enzymes discriminating substrates must be used. Dipeptidyl peptidase IV (DPP IV) is revealed with Gly-Pro-4-methoxy-2-naphthylamide (Gly-Pro-MNA) and Fast Blue B (FBB). It is present in the surface membrane of about 40% lymphocytes of the peripheral blood. Only T-lymphocytes bear the reaction. Reacting lymphocytes belong predominantly to OKT4+ subset. Some OKT8+ lymphocytes also react. With more sensitive substrates (Lys-Pro-MNA, Phe-Pro-MNA and Ala-Pro-MNA) a co-reaction of DPP II was demonstrated "in situ" and in zymograms. In haemoblastoses a positive reaction in cells indicates their derivation from the T-lineage of lymphocytes. A negative reaction does not exclude a T-cell malignancy, however. A decreased number of DPP IV positive lymphocytes in the peripheral blood indicates a diminished immunocompetent potential of T-cells, e.g. immunodeficiency in patients with malignant lymphoma, gastric and colocrectal carcinoma, AIDS, etc. DPP II demonstrated with Lys-Ala-MNA occurs in about 60% of lymphocytes belonging to T and B subsets. It is localized in lysosomes. Although Lys-Pro-MNA is a more sensitive substrate a co-reaction of DPP IV must always be considered. Patients with chronic B-lymphocytic leukaemia displaying a high number of DPP II+ cells usually have a worse prognosis. DPP I assessed with Gly-Pro-MNA and nitrosalicylaldehyde occurs in about 20% of T and B lymphocytes. The number of positively reacting cells increases after corticosteroid therapy. The influence of the treatment on the activity can be shown very well in histograms of DPP I activity measured by computer-assisted microfluorometry.

Cathepsin C↗
PubMed1987

Histochemical detection of alpha-D-glucosidases and their molecular forms with 5-Br-4-Cl-3-indoxyl-alpha-D-glucoside.

5-Br-4-Cl-3-Indoxyl-alpha-D-gluco(pyrano)side was found to be the most suitable synthetic substrate for the demonstration of alpha-D-glucosidases in situ. Using an azoindoxyl procedure with hexazotized pararosaniline or new fuchsine at pH 5 in freeze-dried celloidine-mounted cryostat sections acid alpha-D-glucosidase (EC 3.2.1.20) was shown for the first time in lysosomes of many cells of fetal and adult rat, mouse, guinea-pig, marmoset and human organs. At pH 6.5, in chloroform-acetone pretreated cryostat sections plasma membrane alpha-D-glucosidases were shown in the brush border of enterocytes of the small and large intestine, in the brush border of proximal renal tubule cells and in the stereocilia of the epididymal duct. In an indigogenic procedure with ferricyanide/ferrocyanide as redox catalysator plasma membrane alpha-D-glucosidases were depicted as well as with the azo-indoxyl method; the demonstration of the acid alpha-D-glucosidase was inferior to that achieved with the azo-indoxyl procedure. Using tetrazolium salts as capture reagent intracellular localization was unsatisfactory. In enterocytes, a localization in the Golgi apparatus was shown by the azo-indoxyl procedure only. Analytical isoelectric focusing revealed organ-dependent differences of plasma membrane and lysosomal alpha-D-glucosidases. Compared with the already existing methods the azo-indoxyl and indigogenic procedures are by far the most suitable techniques.

Animals↗
PubMed1987

Dipeptidyl peptidase IV activity in cells of T-lymphoid origin is decreased in cultures with 12-0-tetradecanoylphorbol-13-acetate (TPA).

Dipeptidyl peptidase IV (DPP IV) is a specific enzyme for cells of T-lymphocytic lineage. It has been attempted to induce DPP IV activity in DPP IV negative T-lymphoid leukaemias by 12-o-tetradecanoylphrobol-13-acetate (TPA). Isolated cells from peripheral blood of 6 healthy blood donors and 22 patients with various types of leukaemia were cultivated in RPMI-1640 medium with 20% fetal calf serum alone (control) or supplemented with 20% human placenta conditioned medium (HPCM) or with 16 nmol/l TPA for 3 days. The percentage of DPP IV positive lymphocytes from blood donors remained unchanged in control and HPCM cultures, but decreased significantly in TPA cultures. Leukemic cells from three DPP IV positive cases of acute T-lymphoblastic leukaemia (T-ALL) reacted to the TPA treatment in a similar manner. Leukaemic cells of two DPP IV negative T-ALL cases remained negative in all three types of cultures, thus no induction of DPP IV activity was found. Other normal blood cells as well as leukaemic cells of 7 null-ALL, 1 preB-ALL, 3 B-CLL and 6 AML patients were DPP IV negative before and after cultivation in all types of culture. These findings showed that DPP IV is specifically expressed in cells of T-lymphocytic lineage even after short-term cultivation. HPCM was found to have no effect on DPP IV activity in T-lymphoid cells.

Blood Cells↗
PubMed1987

[Disaccharidases and peptidases of intestinal mucosa after experimental subtotal small intestinal resection with and without retardation of the passage].

Several operating methods for retardation of the passage were compared together after resection of 75% of the mid-small-bowel for preventing a malabsorption syndrome. Morphologic and enzyme-histochemical findings of the intestinal mucosa allow conclusions on the absorptive capacity of the residual intestine. The investigations were carried out one year after the operation. The lay-out of an antiperistaltic segment for the surgical therapy of the short bowel syndrome appears specially suitable after the results of this investigation.

Animals↗
PubMed1987

Possible prognostic significance of the assessment of dipeptidylpeptidase II in peripheral blood lymphocytes of patients with chronic lymphocytic leukemia.

In 115 patients with chronic lymphocytic leukemia (CLL), grouped according to the staging system as proposed by Rai et al., dipeptidylpeptidase II (DPP II) reaction was carried out in smears of peripheral blood using Lys-Pro-MNA and Lys-Ala-MNA as substrates and Fast Blue B (FBB) as the coupling agent in cacodylate buffer, pH 5.5. In patients with stable disease a significantly lower number of DPP II positive lymphocytes was found. On the other hand, a high number of DPP II positive lymphocytes indicated a progressive disease. Lys-Ala-MNA proved to be a better substrate for these purposes. When comparing these results with the stage of the disease proposed by Rai et al., a good correlation was found for Stages 0, I and II. However, in the Stages III, and particularly in the Stage IV, there was a wide range of DPP II values, although the average value calculated from the data of all patients of this group was high. Patients with low DPP II values had usually a stable disease in spite of thrombocytopenia which precluded them from allocation to Stage IV. It is concluded that the assessment of the number of DPP II positive lymphocytes represents a simple and reliable prognostic criteria in patients with B type CLL.

Dipeptidyl-Peptidases and Tripeptidyl-Peptidases↗
PubMed1986

A histochemical method for the demonstration of acetylcholinesterase activity using semipermeable membranes.

The "direct coloring" thiocholine method of Karnovsky and Roots (1964) for the demonstration of acetylcholinesterase (AChE) activity was modified and adapted to the technique of semipermeable membranes. In this way it is possible to demonstrate histochemically both the bound as well as the soluble part of AChE activity. The localization of the reaction product is very distinct. Microdensitometric investigations of results of this method showed a linear increase of the amount of reaction product up to an incubation time of 180 min and section thickness up to 24 micron. The medium supplemented with buffer (instead of agar) can be used for the demonstration of AChE activity in cryostat sections adherent to slides and is also very suitable for the detection of multiple forms of AChE in polyacrylamide or agarose gels.

Acetylcholinesterase↗
PubMed1986

Histochemistry of some proteases in the normal rabbit, pig and ox corneas.

The distribution of activities of membrane aminopeptidases (aminopeptidase M (APM), aminopeptidase A (APA), dipeptidyl peptidase IV (DPP IV), gamma-glutamyltransferase (GGT) and lysosomal exopeptidases (dipeptidyl peptidase I (DPP I), dipeptidyl peptidase II (DPP II)) was investigated in rabbit, ox and pig corneas. Cryostat sections of snap-frozen corneas treated with chloroform-acetone (4 degrees C) were used for the demonstration of membrane-bound enzymes and sections of corneas fixed in 4% paraformaldehyde (4 degrees C) for the demonstration of lysosomal enzymes. In activities of proteases species differences were found. The rabbit cornea was most active, followed by ox and pig corneas. Individual corneal layers reacted differently. Of membrane proteases a high APM activity was found in keratocytes, whereas epithelium and endothelium were negative. On the other hand, APA and GGT were active in the epithelium and endothelium. Their activities in keratocytes were less pronounced. DPP IV activity was demonstrated in some keratocytes beneath the epithelium only. Lysosomal enzymes DPP I and DPP II were active in all corneal layers. The epithelium displayed the highest activity. Differences in activities in the centro-peripheral and epithelio-endothelial directions were found. DPP I, DPP II, and APM were most active in the limbal region in all corneal layers.

Aminopeptidases↗
PubMed1986

The inflow rate of low density lipoprotein cholesterol to the arterial wall in experimental atherosclerosis.

The in vivo inflow rate of low density lipoprotein (LDL) cholesterol to the thoracic aorta, renal and coronary arteries was studied in minipigs with endogenously labelled 3H-cholesterol LDL. The LDL cholesterol inflow rate to these arteries was three to five times higher in animals with hypercholesterolemia and experimental atherosclerosis compared to the controls. Moreover, the inflow rate of LDL cholesterol to the control intact arteries was so high that the cumulation of arterial cholesterol cannot be regarded simply as one-way transport and the amount of cholesterol present in the arterial wall is the result of the equilibrium between LDL cholesterol inflow and transport out from the wall.

Animals↗
PubMed1985

The importance of protease histochemistry in pathology.

The histochemical demonstration of the activities of proteases, based in the majority of cases on the use of discriminating synthetic substrates (aminoacyl or peptidyl derivatives of 4-methoxy-2-naphthylamine [MNA]), has proved very valuable in pathology. Its importance is illustrated by three topics investigated in our laboratory, namely lymphocytes, malabsorption syndrome and atherosclerosis.

Aminopeptidases↗