Immunochemical studies of Toxocara canis proteases.

Proteases of nematodes play a crucial role in larval molting and, in addition to their active role in egg hatching, proteases are also considered a crucial factor in tissue invasion and connective tissue remodeling. In Toxocara canis, proteases play important roles throughout the complex life cycle. They can degrade components of a model of extracellular matrix, basement membranes and different physiological substrates. In the present study, measurements of the proteolytic activity of the perivitelline fluid (PF) surrounding Toxocara canis embryos at different stages of development, the hatching fluid (HF) surrounding the infective larvae, as well as the excretory secretory (ES) products of the larvae in the culture media were performed. Measurements were made using casein as substrate following the Sigma non-specific protease activity assay. The results showed that enzyme activity increased as the embryo matured. The infective larvae were found to continuously produce proteases in the surrounding HF and ES products after in vitro cultivation indicating that Toxocara canis proteases might be important for the worm in the egg and the host. Optimal enzymatic activity was found at pH 8. Incubation of the antiserum from infected mice with the HF and ES products decreased their proteolytic activities, suggesting that there may be a link between the proteases present in these fluids and the immune response.

Immunochemical studies of Toxocara canis proteases

@#Proteases of nematodes play a crucial role in larval molting and, in addition to their active role in egg hatching, proteases are also considered a crucial factor in tissue invasion and connective tissue remodeling. In Toxocara canis, proteases play important roles throughout the complex life cycle. They can degrade components of a model of extracellular matrix, basement membranes and different physiological substrates. In the present study, measurements of the proteolytic activity of the perivitelline fluid (PF) surrounding Toxocara canis embryos at different stages of development, the hatching fluid (HF) surrounding the infective larvae, as well as the excretory secretory (ES) products of the larvae in the culture media were performed. Measurements were made using casein as substrate following the Sigma non-specific protease activity assay. The results showed that enzyme activity increased as the embryo matured. The infective larvae were found to continuously produce proteases in the surrounding HF and ES products after in vitro cultivation indicating that Toxocara canis proteases might be important for the worm in the egg and the host. Optimal enzymatic activity was found at pH 8. Incubation of the antiserum from infected mice with the HF and ES products decreased their proteolytic activities, suggesting that there may be a link between the proteases present in these fluids and the immune response.

Synthetic organic food colouring agents and their degraded products: effects on human and rat cholinesterases.

Most synthetic coloured additives are carcinogenic; teratogenic and cause allergic reactions. In this study, the effects of synthetic azo dyes (sunset yellow FCF and carmoisine), as well as their degraded products (sulphanilic acid and naphthionic acid), on both true and pseudo-cholinesterases (ChEs) are studied. The results indicate that the synthetic azo dyes and their degraded products inhibit both human true and pseudo-ChE activities in vitro. The concentration of coloured additive that cause 50% inhibition (IC50) and enzyme inhibitor dissociation constant (Ki) show that sunset yellow FCF produces greater inhibition of both true and pseudo-ChEs than does carmoisine and sulphanilic acid, while naphthionic acid produces greater inhibition of pseudo-ChE only. Ki indicates that the affinity of sulphanilic acid for both true and pseudo-ChEs is higher than the other three inhibitors. Inhibition of both true and pseudo-ChEs by sunset yellow FCF is of mixed (competitive and non-competitive) type, but carmoisine and sulphanilic acid are non-competitive. Naphthionic acid produces a competitive inhibition kinetic with plasma ChE only. This inhibition is abolished by dialysis, indicating that their effects are reversible. The effects of sunset yellow FCF, carmoisine, sulphanilic acid and naphthionic acid on rat true and pseudo-ChEs are investigated. The data clearly show that there is a significant decrease in enzyme activity. Sulphanilic acid and sunset yellow FCF are the most potent in vivo inhibitors of true ChE and pseudo-ChE, respectively.

Influence of free radicals on cardiovascular risk due to occupational exposure to mercury.

This study was designed to investigate the relation between occupational exposure to mercury and cardiovascular risk, as well as free radicals. The study subjects included 30 male workers exposed to mercury from a fluorescent lamp plant in Alexandria after exclusion of 12 workers with conditions that may bias the results. A matched control group of 20 male subjects were selected from a food industrial plant. The participants were subjected to interview, clinical examination, electrocardiography and R-R deep breathing variability test as a measure of cardiac autonomic function. Spot urine and venous blood samples were collected to measure mercury levels. Free radicals related markers were measured in serum namely lipid peroxide, superoxide dismutase (SOD) activity, catalase activity and glutathione S-transferase. Results showed significant longer electrocardiographic Q-Tc interval, which is corrected to heart rate, in exposed workers than in controls (p=0.002). The R-R deep breathing variability indices were significantly increased among exposed workers in comparison to controls (maximal variation (MV) ratio, p=0.024 & MV rate, p=0.019). The mercury levels in both urine and blood of exposed workers were significantly higher than controls (p<0.0001), with mean levels exceeding the permissible limits. Free radicals related markers revealed significant higher level of lipid peroxide, as well as significant lower levels of SOD activity, catalase activity and glutathione S-transferase among exposed workers than among controls (p<0.0001 for all). Independent relations were observed between Q-Tc and lipid peroxide, and between MV rate and SOD and catalase activities among exposed workers after adjustment for the confounders by multivariate regression analyses. These findings may suspect a cardiac autonomic dysfunction probably related to free radicals in mercury exposed workers. Also, it may through light on some preventive implications.

Metacyclogenesis of Leishmania major in an acidic medium.

An acidic medium was used to stimulate the production of a homogeneous stationary phase promastigotes, morphologically and functionally similar to the in vivo infective form. They possessed a short (< 8 Um) and narrow (< 1.5 Um.) cell body with a flagellum twice or more its length. They were PNA, highly infective to peritoneal macrophages in vitro and expressed high phosphatase activity. By elevating the incubating temperature, almost all of these promastigotes were transformed to amastigotes.

Effect of the carbamate "aldicarb" on acetyl cholinesterase extracted from whole and different parts of rat brain (in vitro and in vivo studies).

Aldicarb, a synthetic carbamate compound used as an insecticide and herbicide, is also employed as a pharmacological cholinergic agent in therapeutic forms. Inhibition of the enzyme AChE, which results in accumulation of ACh, is the basis for its use as an insecticide and it resulted in toxicity in a variety of animals including man. In this work, experiments were carried out in vitro and in vivo to study the effects of aldicarb on the activity of ChE enzyme extracted from whole and five different parts of rat brain, namely: basal ganglia, frontal cortex, medulla oblongata, pons and cerebellum. Kinetic measurements of Michaelis constants (Km), enzyme inhibitor dissociation constants (Ki) as well as the rate of carbamylation (k2c) and binding constants (Kl) for the inhibition of the enzyme obtained from the different parts were done. The carbamylation rate (degree of inhibition of AChE by carbamate) and binding constant for inhibition of whole and different parts of brain in vitro, indicated that the carbamylation rate constants of pons, medulla oblongata and cerebellum were higher than those of other parts. Inhibition of AChE in the different parts of the brain in vitro by aldicarb was of the competitive type, with different enzyme inhibitor dissociation constants (Ki). In vivo studies showed that the inhibition was marked in the enzyme obtained from pons, medulla oblongata and cerebellum; the parts responsible for vital centers and balance which coinsize with the in vitro results.

Respiratory enzymatic changes among workers in glue industries.

The aim of this study was to investigate the respiratory enzymatic changes among workers in glue industries. Blood and urine samples were collected from 30 exposed workers and 30 age and sex matched control subject from the administrative department of the same factory. Different respiratory enzymes were analyzed in blood. The level of urinary phenol was also determined. The median level of different respiratory enzymes (catalase, glutathione peroxidase, glutathione reductase and carbonic unhydrase) were significantly higher in the exposed workers compared to control subjects. Also the median level of urinary phenol was significantly higher in exposed workers compared with that of controls. Attention should be paid to the different occupational health hazard, existing in different types of glue industries.

Effect of physostigmine on cholinesterase activity in different parts of rat brain.

Inhibition of acetylcholinesterase (AChE) in the whole brain, cerebellum, pons, frontal cortex, basal ganglia and medulla oblongata of rat brain by physostigmine (CAS 57-47-6) in vitro was studied. Constants characterizing this inhibition namely: binding constant (KI) and bimolecular rate constant (K'2) were determined. The highest values of K'2 were obtained in the cases of pons and medulla oblongata, the parts responsible for the respiratory and vital centers. The difference in the inhibition of AChE in the different parts of the brain could be due to the difference in the grey and white matters contents in these parts.

Schistosoma mansoni: a comparative study on two cercarial transformation methods.

An agar: gelatin plate method, incorporating varying concentrations of linoleate was devised to measure cercarial penetration and transformation in vitro. Schistosoma mansoni cercariae were stimulated over a wide range of linoleate concentrations, while the transformation process occurred over a narrow range. Penetration rates rose gradually until at linoleate concentrations of 0.3 mM and greater, where penetration approached 100% while transformation just started to occur. The latter then reached maximum (90%) at 3 mM. This optimal concentration of linoleate leading to maximal transformation was then compared with a mechanical transformation method in relation to proteolytic activity and nuclear content. It was found that, proteolytic activity was higher by the chemical than by the mechanical transformation method. The nuclear content decreased by both techniques. This decrease was greater when the mechanical transformation method was applied.