Cholelithiasic disease and associated factors in a Spanish population.

In order to analyze the factors associated with cholelithiasic disease, 1268 participants of a population sample were studied. On univariate analysis, 11 of the 23 variables included showed a statistically significant association (P < 0.05). Five of these variables, including obesity, triglyceride level, intake of hypolipidemic drugs, and a diet rich in cholesterol and saturated fats in women, and physical exercise in men, remained significantly associated after controlling for age. On multivariate analysis among women, a positive association was found with age (P < 0.001), obesity, and the use of hypolipidemic agents (P < 0.05) and a negative one with a diet rich in cholesterol and saturated fats (P < 0.05). Among men, the same analysis revealed there was a positive association with age (P < 0.001) and triglycerides (P < 0.05) and a negative one with physical exercise (P < 0.05). In conclusion, obesity and the use of hypolipidemic agents in women and triglycerides in men, were positively associated with cholelithiasic disease, independent of age, while negative associations included the intake of cholesterol and saturated fats in women and physical exercise in men.

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.

Nucleic acid levels in Anaplasma marginale during experimentally induced bovine anaplasmosis.

The DNA and RNA concentrations in uninfected and Anaplasma marginale-infected bovine erythrocytes were determined. Bovine anaplasmosis was experimentally induced and the nucleic acid levels were followed during the development of the A. marginale infection. Two distinct growth stages were found, the "multiplication" stage and the "transfer" stage. Based on this hypothetycal developmental cycle, the amount of DNA and RNA per Anaplasma initial body was estimated as 73.1 x 10(-3) pg and 45.7 x 10(-3) pg respectively.

The effect of Anaplasma marginale on the glycolytic pathway in bovine erythrocytes.

The glycolytic process in non-infected and A. marginale-infected bovine erythrocytes was studied. The study included four enzymes: hexokinase, phosphofructokinase, pyruvic kinase and lactic dehydrogenase, and the intracellular concentrations of glucose, ATP and 2,3 diphosphoglyceric acid (DPG). The activities of phosphofructokinase and lactic dehydrogenase found in non-infected bovine erythrocytes were fifty times greater than the previously reported values. Glucose and DPG concentrations, hexokinase, pyruvic kinase and lactic dehydrogenase specific activities did not change significantly during experimental anaplasmosis. Phosphofructokinase activity in A. marginale-infected erythrocytes increased to values 300% of those found in intact bovine red cells. ATP concentration in infected erythrocytes decreased to values of 40% of those found in non-infected cells: from 1.60 +/- 0.40 to 0.70 +/- 0.08 mumole per gram of hemoglobin.

Requirement for negatively charged dispersions of phospholipids for interaction with lipid-depleted adenosine triphosphatase.

The basis of the requirement for a net negative charge on phospholipid dispersions able to re-activate lipid-depleted (Na++K+)-dependent adenosine triphosphatase was studied. The origin and density of the charge in phospholipid dispersions were varied before interaction with the adenosine triphosphatase protein, and the charge density on restored phospholipid-adenosine triphosphatase complexes was changed after interaction. The results indicated that: (a) re-activation requires a lamellar arrangement of the lipid molecules with sufficient density of negative charge, but not necessarily negatively charged phospholipid molecules; (b) the net charge appears to be necessary for the correct interaction between the enzyme protein and the phospholipids, although the amount of phospholipid that binds to the protein is also a function of the nature of the acyl chains; (c) it is not possible on the basis of these findings and those in the literature to decide unequivocally if the charge is also required for the enzyme reaction itself. The possible relevance of the findings to the situation in vivo is discussed in terms of the charge being concerned only with lipid-protein interaction.

A simple and rapid method for the reversible removal of lipids from a membrane-bound enzyme.

A simple, rapid and reproducible method for the reversible removal of lipids from a membrane-bound enzyme is described. Essentially, a membrane preparation containing (Na+ + K+)-dependent adenosine triphosphatase was extracted with the non-ionic detergent Lubrol WX in the presence of glycerol, and partial separation of protein from lipid was achieved with the use of only two centrifugations. About 74% of the endogenous phospholipid and 79% of the cholesterol were removed, concomitant with a virtually complete loss of ouabain-sensitive adenosine triphosphatase activity, but with retention of 60-100% of the K+-dependent phosphatase activity. The addition of pure phosphatidylserine re-activated the enzyme to more than 80% of the initial activity, and up to 30% of the protein was recovered. Excess of phosphatidylserine could be washed off the enzyme to give a stable 'reconstituted' preparation. The effects of variation in the experimental conditions were examined, and the results are discussed with respect to the possibility of adapting the method to the study of other lipid-dependent enzymes bound to membranes.