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Light and electron microscopic studies of the rat kidney after administration of inhibitors of the citric acid cycle in vivo. I. Effects of sodium fluoroacetate on the proximal convoluted tubule.

Light and electron microscopic studies of morphologic changes in the rat proximal convoluted tubule after intraperitoneal injection of sodium fluoroacetate (FAc), 60, 20 and 3.5 mg/kg body weight, have been made. Particular attention was directed toward appreciating different changes in the first (S(1)) and second (S(2)) segments of the proximal tubule. The earliest change was loss of mitochondrial granules and pallor of the mitochondrial matrix, not necessarily associated with matrix swelling. Matrix swelling was greatest at 3 hours after 3.5 mg/kg and was reversible. However, the mitochondria retained their elongate shape and cristae persisted. At 48 hours, some mitochondria appeared normal; in others, abnormal matrix densities of unknown nature were present. Mitochondrial changes were similar in S(1) and S(2) at all times. Enlarged apical vacuoles, most pronounced in S(1), occurred in all rats after 20 mg/kg. The change was uncommon after 3.5 mg/kg. The hypothesis proposed is that vacuoles arise during an FAc-induced hyperglycemic phase, when pinocytotic activity is maintained but the normal pathway of glucose catabolism is inhibited. Moderate dilatation of the rough-surfaced endoplasmic reticulum occurred during the first 2-hour period in S(1) and S(2) tubules after high and low doses, but between 6 and 24 hours, dilatation was extensive in S(1) tubules after 3.5 mg/kg. This change was reversible. Two types of abnormal vacuolar bodies, large and small, have been described, and were unique to S(1) tubules. Acid phosphatase activity was demonstrated in a proportion of the small ones, indiciating that they were a type of lysosome. The larger ones shared features in common with cytosomes of control cells, but acid phosphatase activity was not demonstrated in them and their origins and functions remain obscure. The biochemical lesions induced by fluoroacetate have been discussed and a tentative interpretation of some of the morphologic changes has ben made.

Acid Phosphatase↗

Gastroprotective effect of MX1 (a novel salt of the active metabolite of roxatidine with a complex of bismuth and citric acid) against stress ulcers in rats.

We have studied the effect of the newly synthesized agent MX1, a salt of the active metabolite of the H2-blocker roxatidine with a complex of bismuth and citric acid (N-[3-(3-(1-piperidinylmethyl)phenoxy)propyl]-hydroxyacetamide+ ++ -2-hydroxypropane-1,2,3-tricarboxilate-bismuth(3+) complex), against restraint stress ulcers in rats (24 h immobilization). The effects of MX1 (12.5, 50, 125, 184 and 250 mg kg-1) were compared with the effects of equimolar doses of roxatidine (6.5, 25, 70, 100 and 140 mg kg-1) and bismuth subcitrate (6.5, 25, 70, 100 and 140 mg kg-1). The results show that MX1-pre-treatment, at all the doses used, significantly reduces the mean number and size of ulcers. Even at the lowest dose the number of ulcers was reduced by 64.3% and the size of the ulcer by 55.9%. Roxatidine (25, 70, 100 and 140 mg kg-1) dose-dependently reduces ulcer size and number by 24.6, 55.6, 85.3 and 89.0% and by (+7.2), 14.3, 57.1 and 67.9%, respectively. Bismuth subcitrate significantly reduces ulcer size and number only at the highest dose employed (-28.5 and -44.8%, respectively). The morphometric results have been confirmed histomorphologically. The results suggest that MX1 has a gastroprotective effect against stress-induced ulcers which is similar to that of the parent compound and more pronounced than that of bismuth subcitrate.

Animals↗

Influence of sodium tripolyphosphate and citric acid on the shelf life of thornback ray (Raja clavata L.).

Sodium tripolyphosphate dips (5 min in 12% solution) extended shelf life of thornback ray wings by about 2 days, improved the appearance and eliminated weight losses. With citric acid dips (5 min in 0.5% solution) a 3 day extension of storage life was obtained but the treatment had a slight bleaching effect and caused weight losses of about 5%. Both compounds were effective in retarding the breakdown of urea with formation of ammonia in thorback ray.

Ammonia↗

Glass formation in barbiturates and solid dispersion systems of barbiturates with citric acid.

Glasses were prepared from a number of barbiturates. The viscosities and glass transition temperatures of the glasses were dependent on the structure of the groups present on the C-5 and N-1 atoms. Solid dispersions were prepared from three selected barbiturates formulated with citric acid. The glass transition temperatures of these systems indicated that a 1:1 molar ratio complex was formed between the two components and that intermolecular bonding was stronger in the complex than in the individual components.

Barbiturates↗

Scanning electron microscopic studies of root dentin surfaces treated with citric acid, elastase, hyaluronidase, pronase and collagenase.

The effect of topical application of various enzymes to citric acid-demineralized root surface dentin was evaluated using the scanning electron microscope. All of the enzyme treatments appeared to expose more collagen than demineralization alone. Collagenase application appeared to clear all ground substance from the collagen fibrils and may have hydrolyzed some of the fibrils themselves. The other enzymes appeared to clear partially the intercollagenous ground substance.

Citrates↗

Testosterone concentration in testicular venous blood of adult rats and seminal citric acid and fructose concentration as well as weight of accessory sex organs.

In 31 adult rats of Wistar strain (body weight 231 +/- 14g) the relationships between testosterone concentration in testicular venous blood of an individual rat and weight of accessory sex organs (testes, seminal vesicles, ventral prostate, levator ani muscle) and citric acid and fructose concentrations in seminal vesicles were investigated. No direct relationship was found between testosterone concentration and the above parameters. The correlation coefficient varied from 0.042 to 0.394.

Animals↗