Creatine kinase and ATPase activities in piglets fed a fungal mycotoxin co-contaminated diet: Consequences in the pathogenesis of subclinical intoxication.

Creatine kinase (CK) activity, through the creatine-kinase-phosphocreatine (CK/PCr) system, provides a temporal and spatial energy buffer to maintain cellular energetic homeostasis, being responsible to provide adenosine triphosphate (ATP) to the proper function of ATPases enzymes, such as the sodium-potassium (Na+, K+-ATPase) and hydrogen (H+-ATPase) pumps. Thus, the aim of this study was to evaluate the involvement of CK/PCr system in the impairment of energetic homeostasis in piglets fed with a diet co-contaminated with mycotoxins, as well as the effects on ATPases enzymes. Animals were randomly divided in two groups (eight repetitions with two animals each): CON (basal diet) and MYC (mycotoxin diet; 9300 µg/kg of aflatoxins and 8000 µg/kg of fumonisins) which were feed during 15 days. Piglets that received a diet containing 300 µg/kg of aflatoxins and 8000 µg/kg of fumonisins (MYC group) presented lower body weight on days 10 and 15 of experiment when compared to control (CON group). Serum CK activity was lower on days 5, 10 and 15 of experiment in the MYC group. The same occurred for serum Na+, K+-ATPase and H+-ATPase activities on days 10 and 15 when compared to CON group. Moreover, serum calcium levels were superior on day 15 of experiment in the MYC group, while serum potassium and sodium levels were lower in comparison to CON group. Based on these evidences, a diet co-contaminated by aflatoxins and fumonisins inhibits serum CK activity, impairing the energetic homeostasis. This inhibition alters the activities of ATPases (Na+, K+-ATPase and H+-ATPase), contributing to the imbalance of Na+, K+ and Ca+ ionic levels. In summary, the cascade of alterations contributes directly to disease pathogenesis of piglets intoxicated by mycotoxins.

Iron and Oxidative Stress in Parkinson's Disease: An Observational Study of Injury Biomarkers.

Parkinson's disease (PD) is characterized by progressive motor impairment attributed to progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta. In addition to an accumulation of iron, there is also an increased production of reactive oxygen/nitrogen species (ROS/RNS) and inflammatory markers. These observations suggest that iron dyshomeostasis may be playing a key role in neurodegeneration. However, the mechanisms underlying this metal-associated oxidative stress and neuronal damage have not been fully elucidated. To determine peripheral levels of iron, ferritin, and transferrin in PD patients and its possible relation with oxidative/nitrosative parameters, whilst attempting to identify a profile of peripheral biomarkers in this neurological condition. Forty PD patients and 46 controls were recruited to compare serum levels of iron, ferritin, transferrin, oxidative stress markers (superoxide dismutase (SOD), catalase (CAT), nitrosative stress marker (NOx), thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH), advanced oxidation protein products (AOPP), ferric reducing ability of plasma (FRAP) and vitamin C) as well as inflammatory markers (NTPDases, ecto-5'-nucleotidase, adenosine deaminase (ADA), ischemic-modified albumin (IMA) and myeloperoxidase). Iron levels were lower in PD patients, whereas there was no difference in ferritin and transferrin. Oxidative stress (TBARS and AOPP) and inflammatory markers (NTPDases, IMA, and myeloperoxidase) were significantly higher in PD, while antioxidants FRAP, vitamin C, and non-protein thiols were significantly lower in PD. The enzymes SOD, CAT, and ecto-5'-nucleotidase were not different among the groups, although NOx and ADA levels were significantly higher in the controls. Our data corroborate the idea that ROS/RNS production and neuroinflammation may dysregulate iron homeostasis and collaborate to reduce the periphery levels of this ion, contributing to alterations observed in the pathophysiology of PD.

24-hour temporal pattern of NTPDase and 5'-nucleotidase enzymes in rat blood serum.

Circadian rhythms represent an important mechanism to prepare the organism for environmental variations. ATP, ADP, AMP, and adenosine can act as extracellular messengers in a range of biological processes and are metabolized by a number of enzymes, including NTPDases and 5'-nucleotidase. In the present study the authors report that ATPase and ADPase activities present 24-h temporal variations that peak during dark (activity) span. These findings suggest that this enzymatic temporal pattern in blood serum might be important for the normal physiology and function of the organism through the maintenance of extracellular nucleotides at physiological levels.

Effect of different vasodilators on NTPDase activity in healthy and hypertensive patients.

INTRODUCTION: The thrombogenic process that affects the hypertensive patient is associated with regulatory mechanisms present in the vascular endothelium. These mechanisms involve release of an endothelium-derived relaxing factor, ectonucleotidase activity and calcium ion concentration. METHODS: Interference with ENTPDase activity in platelets of hypertensive patients and healthy donors was evaluated for arginine, sodium nitroprusside, and hydralazine. In addition, the kinetic behavior of NTPDase was determined in the presence of the vasodilator that showed the greatest inhibitory influence. RESULTS: Vasodilators decreased NTPDase activity with ATP and ADP as substrates. In controls, hydrolysis was increased in the presence of arginine. Captopril did not affect enzyme activities. The dose response for increasing sodium nitroprusside was biphasic. Kinetic behavior studies were estimated in the presence of sodium nitroprusside, which caused a mixed inhibition. The K(m) values increased and V(max) decreased with increasing sodium nitroprusside concentrations. The IC(50) and K(i) values indicated that the vasodilator was a strong NTPDase inhibitor when tested for the control and hypertensive group, using ATP and ADP as substrate, respectively. CONCLUSION: It is postulated that there was an interaction between vasodilators, NO donors and inhibition of NTPDase.

The effect of stress upon hydrolysis adenine nucleotides in blood serum of rats.

Alterations of enzyme activities involved in adenine nucleotide hydrolysis have been reported in spinal cord and blood serum after repeated restraint stress. On the other hand, no effect was observed in the spinal cord of rats after acute stress. In the present study, we investigated the effect of acute stress on the hydrolysis of adenine nucleotides in rat blood serum. Adult male Wistar rats were submitted to 1-h restraint stress and were sacrificed at 0, 6, 24 and 48 h. Increased ATP and ADP hydrolysis were observed in the blood serum of stressed rats 24 h after stress (58% and 54%, respectively, when compared to controls). On the other hand, the AMP hydrolysis was increased after 6 h (68% when compared to controls) and at 24 h (94% when compared to controls) after stress. The results suggest that altered activity of soluble enzymes in serum may be a biochemical marker for stress situations.

Childhood-onset systemic lupus erythematosus: a comparative study of African Americans and Latin Americans.

This study compared the clinical and serologic features in two different ethnic groups of patients with childhood-onset systemic lupus erythematosus (SLE). One hundred seventy-one SLE patients comprised the study population; 61 (55 girls and 6 boys) were African American with age at onset of 13 +/- 2.9 years, and 110 (97 girls and 13 boys) were Latin American (Colombian) with age at onset of 13 +/- 3.2 years. Clinical, demographic, and laboratory data were obtained by chart review using a standard data collection form. African-American patients more commonly manifested discoid skin lesions, malar rash, pulmonary fibrosis, and pleuritis, and less commonly manifested photosensitivity, livedo reticularis, and vascular thrombosis than did Latin Americans. In addition, there was a higher frequency of anti-dsDNA, anti-Sm, anti-RNP, and anti-Ro positivity among African-Americans compared with Latin-American patients. These results suggest the presence of ethnic differences in the clinical expression of SLE.

Erythrocyte osmotic fragility and cation concentrations during experimentally induced bovine anaplasmosis.

1. The osmotic fragility, the concentrations of Na, K and Ca, the osmolality and the total ATPase activity of bovine erythrocytes from uninfected and Anaplasma marginale-infected bovines were studied in an attempt to correlate these parameters with the decrease in the cellular ATP concentration reported during bovine anaplasmosis. 2. The osmotic fragility found in infected bovine erythrocytes, at 0.52% NaCl, was about two times greater than that observed in non-infected bovines. The increase in osmotic fragility was directly related to the increase in intra-erythrocytic parasitemia. 3. The decrease in ATP concentration reported during bovine anaplasmosis could not be directly related to the increased fragility of these cells. The artificial depletion of erythrocytic ATP did not reproduce the same alteration in the osmotic response to NaCl. 4. The plasmatic and cytoplasmatic concentrations of Na, K and CA did not change significantly during bovine anaplasmosis, whereas the interior of the erythrocytes became hyperosmolal. 5. A. marginale-infected bovine erythrocyte membranes showed an increased ATPase activity when compared to control bovines. Parasite-enriched fractions also presented ATPase activity.

Enzyme activity in paroxysmal nocturnal haemoglobinuria - like red cells

Activities of two membrane enzymes, actylcholinesterase (AChE) and adenosine triphosphatase (ATPase), were studied in a patient with paroxysmal nocturnal haemoglobinuria (PNH), and in PNH-like cells produced by treating normal red cells with 2-aminoethyl isothiouronium bromide. AChE activity was low in the patient with PNH, particularly in the youngest red cells, but ATPase activity of whole blood was normal. AChE activity was decreased in PNH-like red cells, but ATPase activity and the activities of cytoplasmic enzymes were unchanged. These findings indicate that only the superficial part, and not the whole, of the red cell membrane is affected by the PNH lesion (AU)