A bradykinin-potentiating peptide (peptide K12) isolated from the venom of Egyptian scorpion Buthus occitanus.

A nontoxic peptide with bradykinin-potentiating activity was isolated from the dialyzed venom of the scorpion Buthus occitanus by reverse-phase high performance liquid chromatography (RP-HPLC). The pharmacological activity of the peptide was bioassayed by its ability to potentiate added bradykinin (BK) on the isolated guinea pig ileum as well as the isolated rat uterus for contraction. Moreover, the peptide potentiates in vivo the depressor effect of BK on arterial blood pressure in the normotensive anesthetized rat. Chemical characterization of the peptide was also performed. The amino acid composition of the peptide showed 21 amino acid residues per molecule including three proline residues. The amino acid sequence of the purified peptide was confirmed by mass spectrometry. Either N- or C-terminal ends were free. The sequence does not show a homology with bradykinin-potentiating peptides isolated from either scorpion or snake venoms. Furthermore, we did not find a significant sequence homology between the sequence of the isolated peptide and any of proteins or peptides in GenPro or NBRF data banks. The peptide also inhibited angiotensin-converting enzyme (ACE), and could not serve as substrate for the enzyme. It could be concluded that the mechanism of bradykinin-potentiating peptide (BPP) activity may be due to ACE inhibition.

The protective effect of copper complexes against gastric mucosal ulcer in rats.

The study examines the anti-ulcer activity of Cu(I)-(nicotinic acid)2Cl [CuCl(HNA)2]. A dose of 8 mg (23 mumol) of complex/kg body mass was suspended in 0.25% Tween-80 in saline solution and administered intragastrically to male Wistar albino rats which had developed gastric ulcers as a result of pyloric ligation (Shay-rat model). Another group of animals received 5 mg (25 mumol)/kg body mass of the copper-glycinate complex Cu(II)(glycinate)2 [Cu(II)(Gly)2]. Both protected as shown by reduction in the ulcer index, inhibition of gastric perforation and death. Significant increases in gastric juice volume and superoxide dismutase (SOD) activity in the gastric mucosa and blood plasma were found with both copper complexes, while the gastric juice prostaglandin E2 (PGE2) content was significantly decreased in the Cu(II)(Gly)2-treated group, it was significantly increased in the gastric mucosa of the CuCl(HNA)2-treated group. The copper complex-treated animals, especially those which received Cu(II)(Gly)2 had a marked fall in thromboxane A2 (TXA2) levels. These results suggest that intragastric administration of either CuCl(HNA)2 or Cu(II)(Gly)2 produced anti-ulcerogenic activity, with different modes of action.

Some physiological studies on fungi isolated from poultry feedstuffs.

A total of 506 isolates of mesophilic, thermophilic and thermotolerant fungi isolated from the poultry feed ingredients included soybean meals, ground maize, cottonseed cake, wheat bran and fish meal, on glucose-Czapek's agar, Littman oxgall agar at 28 degrees C and yeast starch agar (YPSs) at 45 degrees C, were screened for their ability to produce hydrolytic protease enzyme on solid media. Most of the fungal isolates were able to produce such enzymes but with variable capabilities. The highest proteolytic activity was exhibited by some isolates of Penicillium chrysogenum, Aspergillus flavus, Thermoascus thermophilus and Rhizopus chizopodifarmis. Of all fungal isolates screened for proteolytic activity, Penicillium chrysogenum and Thermoascus thermophilus produced the highest amounts of proteases. These two isolates were used to study the effect of some environmental and nutritional factors on their proteolytic activity. It was found that the highest yield of protease by P. chrysogenum (12.5 units) was achieved 3 days after incubation at 30 degrees C. Marked reduction in protease activity was observed at 37 degrees C. The thermophilic fungus T. thermophillus exhibited maximum (18 units) proteolytic activity 6 days after incubation at 45 degrees C. The enzyme yield was reduced to 13 units at 50 degrees C. Among the seven carbon sources tested, sucrose was the most appropriate for maximum protease production by both P. chrysogenum and T. thermophilus (13.2 and 12.8 units, respectively). Of the sixteen nitrogen sources investigated, NaNO3 was the best inorganic additive nitrogenous salt which induced the highest proteolytic activity by P. chrysogenum and T. thermophilus, whereas DL-tryptophan was the most preferable organic nitrogen compound for maximum protease production by the two fungi tested.

Effect of a bradykinin potentiating fraction, from venom of the Egyptian scorpion, Buthus occitanus, on the ovaries and endometrium of mice.

An isolated fraction with bradykinin potentiating activity, from the venom of the Egyptian scorpion Buthus occitanus, was injected i.p. in female mice (35 days old). Five days after the injection of a single sublethal dose (1 micrograms/g), the number of primary multilaminar and secondary follicles of the ovaries was increased. Graafian follicles were observed in 50% of the treated mice but in none of the control mice. The number and size of the uterine glands and endometrium were increased in treated mice. Concomitantly, estradiol was increased in the circulating blood, while progesterone was within the normal limits. The enhancement of cellular growth by the isolated venom fraction with bradykinin potentiating activity, could be attributed to an enhancement of some growth factor(s) responsible for stimulating the ovarian follicles and uterus.

A spectrophotometric assay for lipid peroxides in serum lipoproteins using a commercially available reagent.

A method is described for measuring lipid peroxides by means of the color reagent of a commercially available test kit for cholesterol estimation. In principle, this assay makes use of the oxidative capacity of lipid peroxides to convert iodide to iodine, which can be measured photometrically at 365 nm. Calibration curves were obtained using peroxides such as H2O2, t-butyl hydroperoxide, and cumene hydroperoxide. A stoichiometric relationship was observed between the amount of organic peroxides assayed and the concentration of iodine produced. Concentrations of lipid peroxides as small as 1 nmol/ml could be measured. The ability to estimate lipid peroxides of isolated low density lipoprotein was demonstrated.

Esterogenic effect of zearalenone on the uterine acetyl cholinesterase in female rats.

A single dose of zearalenone (10 micrograms/g LBW) was injected intraperitoneally to Wistar Albino rats at the age of 50-100 days. The uterine acetyl cholinesterase enzyme was significantly increased in the treated animals compared to that in the controls. Therefore, zearalenone would be considered as an esterogenic effector for increasing the uterine acetyl cholinesterase which enhances uterine relaxation and subsequently improves its function for pregnancy in prematured-animals. Unlike estradiol, it was interesting to find that the estrogenicity of zearalenone was increased by the moderating progesterone hormone. Moreover, it was revealed in this study that the injected dose of zearalenone had no deleterious effects on the pregnant rats at 10-12 days period of gestation. The harmful effects of zearalenone on pregnant animals cited in the literature were reviewed.

The role of copper(I)-nicotinic acid complex on kojic acid biosynthesis by Aspergillus flavus.

Addition of cooper-monovalent-nicotinic acid complex to a synthetic medium specific for kojic acid production by Aspergillus flavus enhanced the production by about 47%. The substance is proposed to act via a biochemical utilization of the copper(I)-B3 complex in a manner similar to that of the naturally utilized nicotinic acid. NAD and NADP like carriers with higher reactivity have been predicted. According to this prediction the biosynthetic route of kojic acid has been interpreted on the basis of a model proposed by Bajpai et al. (1981). In this model the enzymes participating are dependent on NAD and NADP (glucose dehydrogenase and gluconate dehydrogenase) as well as on other reduction processes.

The effect of aflatoxin B1 on the utilization of serum calcium.

The mathematical analysis for plasma disappearance curve of aflatoxicosed animals, subsequently injected with 45Ca was determined. The analysis showed that the three main compartments of the calcium pool (plasma, bone and the labile calcium pool on the surface of bone and soft tissues) had been affected. Specifically, the fractional rate constant for migration of 45Ca from plasma pool to the labile pool had been diminished to its third value. This led to a corresponding reduction in the calcium content of the bone ash. The probable mechanism by which aflatoxin B1 affects calcium dynamics may be interpreted by the inhibitory effect of aflatoxin in the hydroxylation mechanism of vitamin D3 into an active intermediate. During aflatoxicosis (induction of 15 days) the animals entered a state of calcium deficiency, secondary to intestinal absorption inhibition. This was followed by bone resorption and disturbance of the fractional removal rate constant among different calcium compartments.

Aflatoxin and aflatoxicosis: V. The kinetic behaviour of dietary aflatoxins in colostrum drawn from cows postpartum.

This work was conducted in order to study the kinetic behaviour of dietary aflatoxins in the colostrum of a pregnant cow exposed to contaminated feeds for a short period. In this study, two pregnant cows received a single dose of dietary aflatoxins in the form of rice powder contained 31.20 ppm aflatoxin B and 19.68 ppm aflatoxin G during the last stage of pregnancy, at about two weeks before parturition. Samples of colostrum were collected from dams and assayed for the presence of toxic metabolites as well as its conjugations by electrophoretic analysis. The results revealed that the intake of aflatoxins appeared in the colostrum postpartum as AFM1 and also AFB2a which is a non toxic metabolite. Moreover, it was found that the excreted metabolites including AFB2a were conjugated to the immunoglobulin protein fraction of the colostrum. The significance of the obtained results to the newborn calf are discussed.

Binding of aflatoxin B1, G1 and M to plasma albumin.

The aflatoxins B1, G1 and their metabolites exist in the systemic blood as protein conjugate. This conjugation is specific to plasma albumin and proceeds enzymatically by liver and kidney cells. The aflatoxin-albumin conjugate is permanent and the conjugation is an irreversible one. This may interpret the acute liver damage of animal ingested a single dose of aflatoxin (3,4). The existence of bound aflatoxin-albumin in the systematic blood could be considered as one factor of low excretions of aflatoxins and their metabolites in urine (5,6,7).