Biochemical studies of purine catabolism in Ceratitis capitata

1. 1. By using paper chromatography, hypoxanthine, xanthine and uric acid were found in Ceratitis capitata. 2. 2. Xanthine dehydrogenase was prepared from Ceratitis capitata extracts. © 1968

Organ-specific patterns of pteridines in bufo viridis

1. 1. A comparative study of pteridine distribution in different organs of Bufo viridis larvae was made in order to investigate the existence of organ-specific patterns. 2. 2. By using column and paper chromatography, three drosoproteins, 2-amino-4-hydroxypteridine-6-carboxylic acid, xanthopterin, isoxanthopterin, bufochrome, 2-amino-4-hydroxypteridine, hynobius-blue, biopterin, sepiapterin and isosepiapterin were found. 3. 3. A scheme of pteridine biosynthesis in Bufo viridis larvae is proposed. 4. 4. The occurrence of specific patterns in the organs is discussed with respect to their various derivations from the germ layers. © 1967

Effects of reserpine and amphetamine on pteridine pattern and nuclear morphology of Triturus cristatus liver

By means of paper chromatography and the Feulgen reaction the effects of reserpine and amphetamine on the pteridine pattern and nuclear morphology were studied in the liver of Triturus cristatus. It was demonstrated that the Feulgen stainability and state of aggregation of chromatin, as well as the pteridine pattern can be altered by the influence of these drugs. From the results obtained it is suggested that the observed changes in nuclear morphology are due to the interaction of the drugs with the pteridine metabolism. © 1971 Academic Press Inc

Pteridine and Riboflavin Patterns During Tail Regeneration in Triturus Species and the Effects of Chloramphenicol, Isoxanthopterin and Reserpine

In Triturus cristatus amputation causes the reappearance of larval tetrahydrobiopterin, thusraising the ratios tetrahydrobiopterin/isoxanthopterin and tetrahydrobiopterin/riboflavin from zeroto values between 3 — 5. This increase first occurs in the remaining skin and in the eyes. Theincrease of both ratios in the regeneration bud, beginning with the 20th day after amputation, coincides with their drop in both other tissues. Chloramphenicol and isoxanthopterin both stronglyinhibit the formation of a regeneration bud. They also block the increase of both ratios in theremaining skin and in the rudimental regenerate as well. Reserpine induces regenerative ability in Triturus vulgaris, which normally lacks this. It has a strong melanizing effect and, moreover, itcauses an increase of both ratios in the regeneration bud and in the remaining skin. © 1972, Walter de Gruyter. All rights reserved

Pteridine and Riboflavin in Tumor Tissue and the Effect of Chloramphenicol and Isoxanthopterin

Human squamous cell carcinoma has elevated levels of tetrahydrobiopterin. As the level of riboflavin is low, the ratio tetrahydrobiopterin/riboflavin shows values of 5 — 8.3. In contrast, indifferentiated tissues with high metabolic activity but low mitotic rate, like submaxillary glands, elevated levels of tetrahydrobiopterin are accompanied by high content of riboflavin. Thus theratio tetrahydrobiopterin/riboflavin in kept as low as about 0.5. Chloramphenicol and, in particular, isoxanthopterin reduce tumor growth in rats and prevent tetrahydrobiopterin accumulation as well. © 1972, Walter de Gruyter. All rights reserved

The effect of dexamethasone on tissue fibrinolytic system in male and female rats

Background: Dexamethasone in low and high doses affects blood fibrinolytic activity both in animals and humans. In this study the effect of a high dose of dexamethasone on plasminogen activator activity (PAA), t-PA antigen level, plasminogen activator inhibition (PAI) and plasmin inhibition (Pl) in rat heal?, brain, liver, lungs and kidneys was investigated in both sexes. Materials and Methods: Twenty male and twenty female adult Wistar rats were used. Dexamethasone was administered as a single intraperitoneal injection (3mg/kg/day) in rats, once daily, for a period of 5 consecutive days. t-PA antigen level was assayed by an enzyme-linked immunoabsorbant assay method PAA, PAI and PI were determined by spectrophotometric methods. The plasminogen used was isolated from I at plasma. Results: Dexamethasone induced variable changes in the fibrinolytic parameters in mt heart, brain and liver of both sexes; in lungs and kidneys dexamethasone had no effect. Conclusion: These changes of PAA, PAI and t-PA antigen level in heart, brain and liver induced by dexamethasone might be of importance regarding the involvement of glucocorticoids and plasminogen activators/plasmin in many pathophysiological conditions

Gossypol-induced inhibition of plasminogen activator activity in human and ovine acrosomal extract

The effect of gossypol-a polycyclic compound isolated from cotton seeds-on the plasminogen activator activity of man and ram acrosomal extracts was explored in vitro. The action of gossypol on the plasminogen activator activity was investigated by a spectrophotometric method using the chromogenic substrate S-2251. Gossypol, a known antispermatogenic agent, was found to effectively inhibit human and ovine acrosomal plasminogen activator activity. The inhibition was dose-dependent. Plasminogen activator activity from man and ram extracts was completely inhibited by 350 mu mol l(-1) and 300 mu mol l(-1) of gossypol, respectively. In additional experiments, low, non-spermicidal concentrations of gossypol (2.5-40 mu mol l(-1)) were found to significantly inhibit plasmin activity in a dose-dependent manner. The results suggest that inhibition of both acrosomal plasminogen activator and plasmin activity is a possible mechanism by which gossypol exerts its antifertility effect, since the plasminogen activator/plasmin system plays a role in the whole process of ovum fertilization

Inhibition of human and ovine acrosomal enzymes by tannic acid in vitro

The effect of tannic acid, a common flavonoid, on the acrosin and plasminogen activator activity and plasmin activity of human and ram spermatozoa was evaluated. Acrosin and plasminogen activator activity were determined by spectrophotometry using the chromogenic substrates N-alpha -benzoyl-DL-arginine para-nitroanilide-HCl (BAPNA) and H-D-valy-L-leucyl-L-lysine-p-nitroanilide -2HCI (S-2251), respectively. In extracts from both human and ovine acrosomes, the activities of acrosin and plasminogen activators were susceptible to tannic acid inhibition. The inhibitory effect of tannic acid was observed at concentrations > 50 mu mol l(-1) in a dose-dependent manner, in additional experiments, low concentrations of tannic acid significantly inhibited tissue-type plasminogen activator, urokinase-type plasminogen activator and plasmin activity in a concentration-dependent manner over the range 0.25-200 mu mol l(-1). Tannic acid reduced the motility of ram spermatozoa at a concentration of 1000 mu mol l(-1) after 2 and 3 h co-incubation with spermatozoa. The motility of human spermatozoa remained unchanged over the range 0.1-1000 mu mol tannic acid l(-1) during 3 h co-incubation. These results indicate that tannic acid inhibited the activity of both acrosin and plasminogen activator and indicates a possible mechanism by which flavonoids exert their antifertility effects

Plasminogen activator activity in the porcine oviduct during the oestrous cycle

The mammalian oviduct is a dynamic tissue, which lies under the influence of ovarian steroids and produces proteins that affect various stages of fertilization and post-fertilization events. In this study, expression of urokinase-type plasminogen activator (u-PA mRNA) and plasminogen activator activity (PAA) were examined in porcine oviducts by reverse transcription and polymerase chain reaction (RT-PCR) and activity assays, respectively. For this purpose, oviducts were collected from Landrace cycling sows and divided into three segments (isthmus, ampulla, infundibulum). Different concentrations of u-PA mRNA were detected in the three segments following the pattern isthmus > ampulla > infundibulum and this pattern was maintained during the oestrous cycle. On the contrary, the highest PAA was measured in the ampulla compared to the isthmus and the infundibulum and the highest ampullary PAA was detected during the first 2 days of the oestrous cycle. The different regulation of u-PA mRNA expression and PAA is probably due to the existence of PA inhibitors. Recent observations suggest that PAI-1, the main inhibitor of PAs, shows greater expression in the isthmus compared to the ampulla and the local generation of plasmin is inhibited. The latter may be related to observations that spermatozoa are quiescent in the isthmus before fertilization. This study supports the suggestion that urokinase-type plasminogen activator has a biological role within the porcine oviduct, especially at or near the time of fertilization. (c) 2005 Elsevier Inc. All rights reserved