Morphocytochemical reaction of the main exocrinocytes of the proper gastric glands to orchiectomy

In the experiment performed on 52 white male rats by means of light and electron microscopy, cytochemistry and biochemistry, it has been stated that bilateral removal of the testes inhibits proliferation of epitheliocytes in the collum of the proper gastric glands and their differentiation into the main exocrinocytes. This results in decreasing amount of the latter and in development of certain destructive processes in them. They concern mainly the protein-synthesizing apparatus and to a less degree the mitochondrial and lysosomal apparatus. RNA content, ATPase activity oxidoreductase of Krebs cycle and pentose-phosphate shunt decreases, and that of glycolysis increase. Pepsinogen synthesis and its extrusion are inhibited; this is accompanied with a decreased proteolytic activity of the gastric juice. Regenerative processes in the main exocrinocytes are also inhibited.     

Structural changes in the gastric mucosa in experimental hyperthyroidism

Using a structural and functional analysis experiments on rats have shown the morphological substrate of the impaired pepsin secretion in experimental hyperthyroidism. It has been established that enhancement of the proteolytic activity of gastric juice at early times of hyperthyroidism is linked with activation of biosynthetic processes in the chief gastric cells. Under the conditions of prolonged hyperthyroidism, the reduced proteolytic activity of gastric juice is caused by inhibition of both bioenergetic and biosynthetic processes in the chief cells.     

Morphofunctional changes in the parietal cells of the stomach after adrenalectomy

As demonstrated experiments performed in 150 white male rats by means of light and electron microscopy, cytochemistry with successive morpho-, cytophotometric and biochemical analysis, after bilateral adrenalectomy, inhibition of proliferative processes of cervical epitheliocytes and their differentiation into parietal cells take place. This results in decreasing amount of the latter, in appearance among them not completely differentiated forms. Dystrophic processes develop, manifesting as a decreasing balance of the secretory membranes and destruction of the mitochondrial apparatus, accompanied with a sharp drop in activity of the main oxidoreductases and ATP-ase. The gastric juice acidity decreases. These changes depend mainly on deficiency of glucocorticoid hormones, but not mineralocorticoids.     

Characterisation of the barrier caused by luminally secreted gastro-intestinal proteolytic enzymes for two novel cystine-knot microproteins

It was the aim of this study to evaluate the stability of two novel cystine-knot microproteins (CKM) SE-ET-TP-020 and SE-MC-TR-020 with potential clinical relevance towards luminally secreted proteases of the gastrointestinal tract in order to gain information about their potential for oral administration. Therefore, the stability of the two CKM and the model-drug insulin towards collected porcine gastric and small intestinal juice as well as towards isolated proteolytic enzymes was evaluated under physiological conditions. No intact SE-ET-EP-020 was detected after few seconds of incubation with porcine small intestinal juice. SE-ET-TP-020 was also degraded in porcine gastric juice. Furthermore, SE-ET-TP-020 was extensively degraded by isolated chymotrypsin, trypsin and pepsin. Moreover, it was degraded by elastase. SE-MC-TR-020 was degraded entirely within approximately 2 h when incubated in porcine small intestinal juice, whereas no degradation was observed within a 3 h incubation period with porcine gastric juice. In presence of the isolated proteolytic enzymes, SE-MC-TR-020 was only slightly degraded by trypsin and pepsin, whereas elastase caused no degradation to SE-MC-TR-020 at all. Chymotrypsin was the protease that caused most degradation to SE-MC-TR-020. The model drug insulin was degraded extensively by chymotrypsin, elastase, pepsin and trypsin as well as by porcine gastric and porcine small intestinal juice. In conclusion, a precise characterisation of SE-ET-TP-020 and SE-MC-TR-020 degrading luminally secreted GI enzymes has been made, which is an important and substantial prerequisite for the further optimisation of these CKM.     

Characteristics of gastric secretion in suckling calves.

In the investigations on five calves with fistulae in the abomasum and oesophagus the secretion of gastric juice as well as its content of proteolytic enzymes and hydrogen ions were measured. It was found that the gastric juice of calves possessed a fairly high proteolytic activity (about 6 UP/l) and hydrogen ion level already on the 3rd day of life. Sham feeding produced two different types of gastric secretion response, depending on the age of calves. In the first week of life sham feeding caused an inhibition of secretion which became more intensive only about 30 min following food administration. In the second week of life gastric juice secretion increased immediately after feeding.     

Effect of adrenalectomy on the gastric juice secretion evoked by food or histamine in dogs

Comparison was made of the effect of total adrenalectomy on the gastric secretion in chronic experiments on dogs with the Pavlov's stomach and Basov's fistula. A decrease of the maximal secretion level of gastric juice was associated with the alteration of the organ hemodynamics. A tendency to reduction of the acid production in the stomach was revealed. Essential differences were noted in the character of proteolytic enzymes secretion with different agents stimulating the secretion. Specific nature of the gastric secretory system for each stimulant, and different effects of adrenalectomy on the secretion induced by these stimulants was shown.     

Effect of altered hormonal balance in the mother-fetus system on body weight, the adrenal glands, thymus gland and peripheral blood leukocyte composition in the offspring

Pregnant rats have been injected intramuscularly with hydrocortisone-acetate or desoxycorticosterone-acetate (DOCA) for the III or the II-III trimesters of pregnancy. In the last case the animals are given not only greater doses of the hormones, but during a longer period. By the end of the pregnancy the drug dose decreases. In mother-rats after hydrocortisone injections the adrenals mass increases; after DOCA the body mass increases, and that of the adrenals drops. In the offspring hydrocortisone produces decline of the thymus and adrenals mass, as well as neutrophilic leucocytosis, lympho-, eosino-++- and monocytopenia. Just the opposite, DOCA results in lympho- and monocytosis, in increasing morphofunctional activity of monocytes. Common effects in hormonal action is demonstrated as underdevelopment of the adrenals, in decreasing thymus mass, in development of neutrophilic leucocytosis and eosinopenia. With increasing doses and duration of prenatal injections of corticosteroids in rats the mass of the adrenals and thymus drops even greater, stimulating effect of the hormones on the neutrophilic granulocytopoiesis decreases.     

Translation of mRNA from rat-liver polysomes into tyrosine aminotransferase and tryptophan oxygenase in a protein-synthesizing system from wheat germ. Effects of cortisol on the translatable levels of mRNA for these two enzymes.

Messenger RNA was isolated from rat liver polysomes by phenol/chloroform extraction and subsequent oligo(dT)-cellulose chromatography. The mRNA was translated in a protein-synthesizing system in vitro derived from wheat germ. The system was optimized in respect to Mg2+ and K+. The presence of spermidine or spermine is necessary for the synthesis of polypeptides having molecular weights of over 20 000. In the absence of the bases only small molecular weight products are formed. The amount of protein synthesized is linearly dependent on the amount of mRNA added up to concentrations of 80 mug mRNA/ml. The synthesis of tyrosine aminotransferase and tryptophan oxygenase in the system in vitro has been demonstrated by specific immunoprecipitation and sodium-dodecylsulfate polyacrylamide gel electrophoresis of the precipitate with enzyme proteins as marker. The amount of specific product formed is linearly dependent on the amount of mRNA present. The amount of translatable tyrosine aminotransferase mRNA and tryptophan oxygenase mRNA increases after administration of hydrocortisone to adrenalectomized rats. At low doses of hormone (2 mg/100 g body weight) maximal values are observed at 4 h, control levels being reached at 6-8 h after hormone application. With higher doses of hydrocortisone (20 mg/100 g body weight) maximal values are attained at 6 h, tending to control levels 14 h after treatment. The enzyme activity curves are parallel to the mRNA curves, the peak of enzyme activity occurring 2 h after the peak of mRNA activity.     

CCK-58: A novel reagent for studying the regulation of cholecystokinin bioactivity

CCK-58 has been shown to be the major circulating form of the hormone in the dog and human. To date, there have been no reports on its biological activity in vivo. We report here that CCK-8 and CCK-58 were equipotent in decreasing gastric motor function after bolus doses and in stimulating protein secretion after continuous infusion in urethane-anesthetized rats. The present results are the first on the in vivo activity of CCK-58, and indicate that because CCK-58 is equipotent to CCK-8, and because it is a major released and circulating form, it may be considered as a major contributor to the expression of cholecystokinin bioactivity.     

Compensation of exocrine pancreatic insufficiency during its partial, subtotal and total resection

Chronic experiments on dogs have shown that the damage of extra-secretory pancreatic function by duct ligation caused marked compensatory changes of stomach function. The increase in gastric juice secretion and gastric juice proteolytic activity was accompanied by the reduction in its acidity. In addition to quantitative changes, qualitative shifts were revealed (amylolytic activity in strongly acid pH-reaction), never observed in the gastric juice of intact animals. Partial pancreas resection (up to 75%) both in control and test animals 10-14 months after pancreatic duct ligation was not accompanied by significant changes in gastric juice secretion. Total pancreas resection in dogs with previous pancreatic duct ligation caused neither prompt animal death, as in the control, nor the inhibition of compensatory reactions of gastric juice secretion.     

The self-regulation elements in the stomach secretor response to perturbing effects

By the levels of stomach juice volume, its proteolytic activity, hydrogen ion activity, secreted mucus volume, the experimental dogs with stomach fistula were divided into two groups: with low and with high levels of secretion. The perturbing effects involved immobilization stress, mineral water, prolin-containing peptide Gly-Pro. One of the self-regulation mechanisms involved an "initial background rule": if the initial level of the secretion parameters is low, then it grows following the effect, whereas if it is high--it becomes lower. The rule was most evident in the stomach juice secretion complex-reflex phase.     

Morphofunctional characteristics of the endocrine cells of the stomach following administration of hydrocortisone and L-thyroxine

Electron microscopy with application of specific fluorescent histochemical reaction of Falck, as well as some methods of impregnation made it possible to indentify enterochromaffin cells in the stomach of hyperthyroid rats and the rats after cortisone injection under the conditions ox hyperfunction of the thyroid gland. After 20 days of L-thyroxin injection, and after 10 days of hydrocortisone injection, preceded by L-thyroxin, the amount of enterochromaffin cells in the epithelial layer of the gastric mucosa were noted to increase that was accompanied by simultaneous increase of the number of secretory argyrophil granules in their cytoplasm. Simultaneous injection of L-thyroxin and hydrocortisone, while not decreasing statistically significant amount of the cells, produced degradation of their cytoplasm.     

Small doses of capsaicin given intragastrically inhibit gastric basal acid secretion in healthy human subjects.

Although the direct inhibitory effect of small dose of capsaicin on gastric secretory responses was proved in animal observations, the role of capsaicin-sensitive afferent nerves (CSAN) and the effect of capsaicin applied in small and high doses on gastric secretion in human has not been clarified yet. In this study we investigated the influence of different small doses (100-800 microg) of capsaicin given intragastrically through an orogastric tube on gastric basal secretory responses in 10 healthy human subjects. Gastric basal secretory responses (volume, H+-concentration, H+-output) were measured from the suctions of gastric juice for a 1-h period. It has been found that: a) capsaicin dose-dependently inhibited the volume and H+-output of gastric juice; b) ID50 was found to be about 400 microg for capsaicin on gastric acid secretion; c) the time interval for capsaicin-induced gastric inhibition existed for about 1 h indifferently from the higher dose (800 microg) of capsaicin given after. It has been concluded that the capsaicin (given in small doses) inhibits the gastric basal acid output via stimulation of the inhibition of capsaicin sensitive afferent nerves.     

Relation Between Testosterone Levels in Serum and Proteolytic Activity in the Neck Muscles of the Norwegian Reindeer (Rangifer tarandus tarandus)

The characteristic hypertrophying of the male reindeer neck muscles during the rutting period, which coincides with the rise in serum testosterone levels, is found to be accompanied by a significant decrease in lysosomal proteolytic activity of the neck muscle cells. Conversely, during the period of neck muscle involution following the rapid decline in serum testosterone after the rut, a marked increase in neck muscle proteolytic activity is found. These changes in lysosomal activity do not parallel the changes in feed consumption and nutritional stage of the animals during the rutting period. The lysosomal proteolytic activity of the male reindeer neck muscles thus may be, at least partly, under the control of sex steroid hormones.     

Regulation of a Sulfur-Controlled Protease in Neurospora crassa

Wild-type Neurospora crassa produces and secretes extracellular protease(s) when grown on a medium containing a protein as its principle sulfur source. Readily available sulfur sources, such as sulfate or methionine, repress the synthesis of the proteolytic activity. Preliminary characterization of the proteolytic enzyme shows it to have a molecular weight of about 31,000, a pH optimum of 6 to 9 with casein as substrate, and esterolytic activity against acetyl-tyrosine ethyl ester with a pH optimum of 8.5. The enzyme activity is completely inhibited by diisopropylfluorophosphate, partially inhibited by ethylenediaminetetraacetate, but unaffected by iodoacetate. The proteolytic activity is temperature labile and is reduced by 75% within 15 min at 60 C. Synthesis of the protease activity is induced by proteins, and to a lesser extent by large-molecular-weight polyamino acids, but not at all by small peptides or amino acid mixtures. During conidial out-growth, the protease(s) first appears at about 8 h and continues to increase while the cells are in an active growth phase. When a low concentration of sulfate is present, the protease(s) is not produced until about 18 h, suggesting that the sulfate must first be used by the cells before the protease is either synthesized or released.     

Effect of insect larval midgut proteases on the activity of Bacillus thuringiensis Cry toxins

To test the possibility that proteolytic cleavage by midgut juice enzymes could enhance or inhibit the activity of Bacillus thuringiensis insecticidal toxins, once activated, the effects of different toxins on the membrane potential of the epithelial cells of isolated Manduca sexta midguts in the presence and absence of midgut juice were measured. While midgut juice had little effect on the activity of Cry1Aa, Cry1Ac, Cry1Ca, Cry1Ea, and R233A, a mutant of Cry1Aa from which one of the four salt bridges linking domains I and II of the toxin was eliminated, it greatly increased the activity of Cry1Ab. In addition, when tested in the presence of a cocktail of protease inhibitors or when boiled, midgut juice retained almost completely its capacity to enhance Cry1Ab activity, suggesting that proteases were not responsible for the stimulation. On the other hand, in the absence of midgut juice, the cocktail of protease inhibitors also enhanced the activity of Cry1Ab, suggesting that proteolytic cleavage by membrane proteases could render the toxin less effective. The lower toxicity of R233A, despite a similar in vitro pore-forming ability, compared with Cry1Aa, cannot be accounted for by an increased susceptibility to midgut proteases. Although these assays were performed under conditions approaching those found in the larval midgut, the depolarizing activities of the toxins correlated only partially with their toxicities.     

Ultracytochemical study of oxidoreductases in the parietal cells of the gastric mucosa in gastric cancer

Ultracytochemistry was used to study and compare cytochromooxidase, succinate dehydrogenase and NADH-dehydrogenase activity in gastric mucosa parietal cells in health and in gastric carcinoma associated with decreased acidity of gastric juice. The study demonstrated the reduced activity of the enzymes listed in the mucosal parietal cells in gastric carcinoma. This finding is interpreted as a consequence of disturbed energy supply of hydrochloric acid secretion in gastric carcinoma.     

Structure and cytophysiology of gastric endocrine gland cells after repeated administration of testosterone propionate

By means of light, electron microscopy and morphometry methods contents and structural organization of endocrinocytes have been investigated in gastric glands of rats, to whom testosterone propionate has been injected for 5, 10, 15, 20 days. The hormone produces certain stimulating effect on the endocrine apparatus function. During the first stages of the experiment most of the endocrinocytes are at the state of active secretion; this is testified as a decreasing composition of histochemically revealed cells in epithelium and their degranulation. During the following stages the process of synthesis is activated in the cells and their amount increases. Appearance of numerous agranular, poorly differentiated endocrinocytes and exo-endocrine cells demonstrates certain intensification of cytogenesis of endocrinocytes in the gastric epithelium. The changes observed are considered as adaptive, directed to stabilize homeostasis, when the hormonal balance is disturbed.     

The influence of testosterone on the alkaline proteolytic activity in rat skeletal muscle

The effects of testectomy and subsequent administration of testosterone propionate on the activity of the alkaline proteinases in rat skeletal muscle were investigated. Castration of the mature rat was followed by a short-term delay in protein accretion in skeletal muscle tissue as measured by the protein/DNA ratio and was paralleled by a 2–3 fold increase in specific activity of the alkaline proteinase(s). This increase of proteolytic activity was equally significant when expressed relative to μg DNA. Although the gain in body weight was significantly lower in the castrated rats, nevertheless the protein/DNA ratio in muscle after 6 weeks approximated the values of sham-operated control rats without normalization of the proteolytic activity.Treatment of the castrated rats with testosterone propoinate resulted in restoring normal levels of previously elevated levels of alkaline proteolytic activity in muscle tissue. The normalization of enzyme activity as well as protein accretion in muscle was dose-dependent. Treatment of the rats with a low dose (0.1 mg/day) of testosterone propionate failed to restore the proteolytic activity, but led to a small increase of the protein/DNA ratio as well as to a progressive increase in body weight. These data indicate a regulatory role of testosterone in the adaptive behaviour of the alkaline proteolytic system in rat skeletal muscle.     

The effect of whole-body X-irradiation of guinea pigs on liver ribosomes

1. The size distribution of aggregates of liver ribosomes and their protein-synthesizing ability in vitro were studied shortly after X-irradiation of guinea pigs. 2. Sucrose-density-gradient analysis of the mitochondrial supernatant after treatment with deoxycholate revealed a gradual increase in the number of polysomes, reaching a maximum between 9 and 15 hr. after irradiation. At that period the amount of ribonucleoprotein particles reached a level 25-30% above the control. This finding was confirmed by analytical-ultracentrifugal analysis and electron microscopy. Experiments were conducted to exclude the possibility that the enrichment of polysomes in the irradiated animals had occurred during the isolation procedure. 3. The protein-synthesizing ability of total ribosomal particles was measured in vitro. This showed an increase in amino acid incorporation parallel to the progressive enrichment of polysomes. At radiation doses of up to 1000r. the protein-synthesizing capacity was dependent on the radiation dose: the higher the dose the higher the amino acid incorporation, reaching 40-60% above the control at the period of maximal polysome enrichment. Amino acid incorporation remained at this level after radiation doses of between 1000 and 3000r. The enhanced protein-synthesizing activity was due solely to the increase in the proportion of polysomes, since irradiation was without effect on the activity of single ribosomes. 4. The results of the experiments are discussed in the light of our knowledge of the effect of radiation on protein synthesis.