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Biomedical subjects

Z Lojda

Publications and source records attributed to Z Lojda.

At least 163 records · Page 9Linked to original sources
PubMed1977

Intestinal gradient of enterokinase activity in different species of animals.

The proximodistal gradient of enterokinase activity was studied in mucosal homogenates of the duodenum, jejunum, ileum, caecum (or megacaecum) and sigmoid flexure of various mammals. The study was carried out in groups of 5 monkeys, guinea pigs, dogs and rats and also in gnotobiological rats--conventional (n = 5), germ-free (n = 10) and monocontaminated (n = 5) with Escherichia coli 0 86. Enterokinase activity was likewise determined in duodenal mucosal homogenates prepared from material resected at operation from adult humans (n = 5) and from a group of monkeys (n = 5), with and without the addition of Triton X-100. Enzymatic activity was determined by a modification of Nordström and Dahlqvist's method, using pH-stat titration. In all the animals, enterokinase values were unequivocally the highest in the duodenal mucosa; in the other intestinal segments it displayed a marked aboral decrease, so that we found about 30% of duodenal activity in the jejunum, trace amounts in the ileum and zero values in the caecum and the sigmoid flexure. In the individual animals, the enterokinase activity values fell in the sequence monkey greater than guinea-pig greater than dog greater than rat. Enterokinase activity in the human duodenum was practically the same as in the rat duodenal mucosa. No reciprocal differences were found in gnotobiological rats. Either whole homogenate or the supernatant of triton-treated homogenate can be used for the demonstration of enterokinase in laboratory practice. The only part which can be employed for diagnostic purposes in duodenal mucosa.

Animals↗
PubMed1977

Biochemistry and immunochemistry of membrane-bound enzymes.

Membrane-bound enzymes have certain specific differences compared with soluble enzymes. Membrane-binding often enables greater catalytic activity of associated enzymatic reactions, their regulation by low molecular weight substances (substrates and allosteric effectors, hormones) and compartmentation, etc. On the other hand, the binding of enzymes to membranes causes considerable difficulties as regards their isolation and the determination of their homogeneity and substrate specificity. Membrane enzymes provide a unique opportunity for studying the biogenesis of membranes and their physiological properties, however. These problems are discussed in relation to two types of membranes--the inner mitochondrial membrane and the membrane of the brush border of the small intestine. An example of the utilization of immunochemical methods is given in the results of a study of biosynthesis of the cytochrome oxidase complex in yeast cells. In the case of the brush border of the mammalian small intestine, the fact that certain enzymes, which are also of clinical significance from the aspect of congenital genetic defects, can be isolated only as complexes, constitutes a very real problem. This applies particularly to the sucrase-isomaltase complex and the lactase-beta-glucosidase complex. Solving questions of substrate specificity is of significance for the choice of a suitable analytical or histochemical method. The common regulation of these complexes gives an insight into the problems of membrane biogenesis, however. Immunochemical methods can be employed as sensitive criteria to support biochemical and morphological studies. Collaboration between the biochemist and histochemist proved especially valuable when determining the substrate specificity of enzymes (glycosidases) in relation to histochemical substrates, when applying histochemical methods for detecting enzymatic activity in immunoprecipitates and acrylamide gels and in immunohistochemical studies of the localization and developmental differentiation of the enzymes of the brush border of the small intestine.

Animals↗
PubMed1977

Demonstration of "hetero-beta-galactosidase" "in situ".

A method for the histochemical demonstration of "hetero-beta-galactosidase" was elaborated. The enzyme is demonstrated in cryostat sections by the semipermeable membrane technique. Pairs of membranes--one pre-washed in saline--are used. The most sensitive method is post-coupling demonstration with 6-Br-2-naphthyl-beta-D-glucoside. The incubation time must be short, to avoid diffusion. The method allows cellular localization. The method with alpha-naphthyl-beta-D-glucoside and hexazonium-p-rosaniline is less sensitive, but localization is better. Indigogenic methods are the least sensitive. The enzyme is localized in the supranuclear zone of differentiated enterocytes of the human, monkey and rabbit small intestine, with maximum activity in the jejunum. The activity of the enzyme is low in patients with coeliac sprue, in the active phase of the disease. In isolated lactase deficiency it is normal. In the kidney, the enzyme is localized chiefly in the cytoplasm of the proximal tubule cells.

Animals↗
PubMed1976

Histochemistry of some acid hydrolases in striated muscles of the rat.

The distribution of acid phosphatase, beta-N-acetylglucosaminidase, beta-glucuronidase, and acid beta-galactosidase was studied in mm. extensor digitorum longus, soleus, and diaphragm of rats. Using the technic of semipermeable membranes activities of these enzymes were demonstrated beside cells of the interstitial tissue in muscle fibers themselves as well. Acid phosphatase displayed the highest activity which appeared in many small dots dispersed in the fiber. The activity of acid phosphatase was about 1.2 X higher in the m. soleus than in the m. extensor digitorum longus. In the latter muscle a somewhat higher activity was often found in muscle fibers displaying a higher staining for NADH tetrazolium reductase. The activity of beta-N-acetylglucosaminidase was slightly lower, that of beta-glucuronidase very weak but still discernible. The activity of acid beta-galactosidase was not ascertained in the majority of fibers. The ratio of activities measured in an area of the same size in cells of the interstitial tissue and in muscle fibers amounted in average to 2.6:1 in the case of acid phosphatase, 2.5:1 in the case of beta-N-acetylglucosaminidase, 5.7:1 in the case of beta-glucuronidase, and 44.3:1 in the case of acid beta-galactosidase. The importance of the histochemical technic in studies concerned with acid hydrolases in striated muscle fibers in normal and pathological conditions is pointed out.

Acetylglucosaminidase↗
PubMed1976

Changes of acid phosphatase activity of fast and slow rat muscles during ontogenetic development.

1. The activity of acid phosphatase (AP) were studied both bio- and histochemically in fast and slow muscles of the rat during postnatal development. 2. Both biochemical and histochemical methods show at birth a similar, high AP activity in both, fast and slow muscles. From 20 days onward AP activity is higher in the slow soleus than in the fast extensor digitorum longus (EDL) muscle. 3. Fibres with high AP activity have also higher activities of oxidative enzymes and of non-specific esterase (NSE). This property is not coupled to degree of ATP-ase activity; fibres with high or low ATP-ase activity reveal similar activities with respect to AP. 4. There is a "two-phase" developmental change in the degree of enzyme activity in both the fast EDL and slow soleus muscles. AP activity is high at birth, decreases during later postnatal development and increases again in senescent muscles.

Acid Phosphatase↗
PubMed1976

Uneven distribution of alkaline phosphatase in individual layers of rabbit and ox cornea. Histochemical and biochemical study.

In the rabbit and bovine cornea the activity of alkaline phosphatase using histochemical as well as biochemical methods was investigated. Biochemically the enzyme activity was studied in separated corneal layers. In the histochemical investigation the best results were obtained in cryostat sections using the azocoupling method with naphthol AS-MX phosphate and Variamine Blue RT Salt. The enzyme activity was found not only in the epithelium and endothelium (as was described previously) but even in keratocytes. The mutual relation of activities in the epithelium and in keratocytes differed in both species. The overall activity found by histochemical methods is in good agreement with the biochemical determination of alkaline phosphatase (p-nitrophenyl phosphate as the substrate). Besides the histochemical approach shows an uneven distribution of alkaline phosphatase activity in individual cells which cannot be assessed by the biochemical determination.

Alkaline Phosphatase↗
PubMed1976

[Studies of potassium and sodium in ischemic changes of the human myocardium].

The results are presented of investigations concerning the potassium-sodium ratio in the human myocardium under ischaemia in correlation with macroreaction to dehydrogenases. The values found, though approaching those of the familiar experimental results, can hardly be regarded as reliable in diagnosing early ischaemic changes in autopsy material since they are affected by post-mortem changes.

Coronary Disease↗
PubMed1975

The use of hexazonium-p-rosanilin in the histochemical demonstration of peptidases.

The suitability of hexazonium-p-rosanilin (HP) in the histochemical demonstration of peptidases was investigated. The detection was carried out in cold mictrotome sections adherent to slides or semipermeable membranes. Alanyl-1-naphthylamide, alanyl-2-naphthylamide, leucyl-2-naphthylamide, leucyl-4-methoxy-2-naphthylamide (all substrates in concentration of 0.4 mg/1 ml of citrate phosphate buffer pH 6.5), gamma-L-glutamyl-1-naphthylamide, gamma-L-glutamyl-2-naphthylamide (both substances in concentration of 0.24 mg/1 ml of acetate buffer pH 6.5) were used as the substrates. Results were compared with those obtained with Fast Blue B and Fast Garnet GBC. In comparison with Fast Blue B and Fast Garnet GBC HP is a faster coupler, furnishes azodyes which are stable, amorphous (even without lipid extractions from sections), more substantive and in the case of 1-naphthylamine almost insoluble in ordinary lipid solvents used for the dehydration and clearing of sections before mounting. The molecular extinction coefficient of azodyes furnished by HP is 1.5X higher for 1-naphthylamine than for 2-naphthylamine. It is higher than that of Fast Garnet GBC, however, lower than that of Fast Blue B. The inhibitory influence of individual diazonium salts on enzyme activity (activities) splitting leucyl-2-naphthylamide amounts to 36% (Fast Garnet GBC), 37% (Fast Blue B), 52% (HP, 0.03 ml/1 ml) and 63% (HP, 0.09 ml/1 ml) at pH 6.5. For gamma-glutamyl-transpeptidase the corresponding values are 50%, 59%, 62% and 67%. The higher inhibitory influence of HP is compensated by the possibility of its using in the technic of semipermeable membranes. HP improves greatly the localization of peptidases in cold microtome sections from which lipids were not extracted. The best results are furnished by 1-naphthylamine dervatives. In the case of 4-methoxy-2-naphthylamine derivatives the localization is very sharp, however, the azodye is less distinct than that of 2-naphthylamine. The localization as obtained with HP in combination with substrates derived of simple naphthylamines is similar or even better than with 4-methoxy-2-naphthylamine derivatives applied with Fast Blue B. Typical examples are shown.

1-Naphthylamine↗