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Biomedical subjects

A Guerra

Publications and source records attributed to A Guerra.

At least 37 records · Page 2Linked to original sources
PubMed2001

Exogenous sphingosine enters Xenopus laevis embryos grown in petri dishes and it is metabolized.

Xenopus embryos of different developmental stages were exposed to 0.1 microM [1-3H]sphingosine. Labeled sphingosine was quickly absorbed by Xenopus embryos. The amount of radioactivity absorbed increased with embryo age and appeared to be linearly correlated (R = 0.97) to the embryo surface area. About 45% of the total radioactivity associated to the embryos was found in the skin, 22% in the intestine, 15% in the heart, 12% in the liver and 6% in the brain. A portion of [1-3H]sphingosine entered very rapidly the biosynthetic pathway of sphingolipids; after 30 min of incubation, in fact, only a small amount of free radioactive sphingosine could be detected. Sphingomyelin was the main radioactive sphingolipid synthesized; radioactive ceramide, galactosylceramide and lactosylceramide could also be recognized and quantified. On the contrary, the amount of radioactive gangliosides was hardly detectable. A portion of [1-3H]sphinogosine absorbed by Xenopus embryos (30 to 60% depending on the developmental stage) entered the catabolic pathway producing radioactive phosphoethanolamine that was recycled for the biosynthesis of radioactive phosphatidylethanolamine. This phospholipid was produced mainly in the intestine and in the skin, while sphingomyelin was the main radioactive lipid in the heart, liver and brain.

Animals↗
PubMed2001

Dermatoglyphics and abnormal palmar flexion creases as markers of early prenatal stress in children with idiopathic intellectual disability.

A number of studies have shown the importance of dermatoglyphics as markers of prenatal disturbance in developmental disorders of unknown origin. Genetic and non-genetic factors are involved in the aetiology of intellectual disability (ID), although the cause remains unknown in up to 50% of cases. The aim of the present study was to analyse dermatoglyphic traits and abnormal palmar flexion creases as markers of environmental prenatal stress in children with idiopathic ID (IID) using a case-control study design. Three dermatoglyphic variables, which have been reported as altered in other congenital disorders, were considered were studied in a sample of 62 children with IID (IQ < 70) and 75 healthy controls (IQ > 70): (1) fingerprint patterns; (2) total a-b ridge count (TABRC); and (3) abnormal palmar flexion creases (APFCs). More arches, the simplest fingerprint pattern, and more radial loops, an unusual pattern, were found in IID cases in comparison to controls (chi23 = 9.26; P = 0.02), with especially marked differences in boys (chi23 = 6.5; P = 0.0008). A significant increase of APFCs was also found in the affected children (chi24 = 28.52; P < 0.00; odds ration = 3.86, 95% confidence interval = 1.77-8.47). For TABRC, the differences between IID cases and controls failed to reach the conventional level of significance. These findings suggest that environmental factors acting early in development, or mechanisms involving an interaction of genotype and environment could be involved in the aetiology of some cases of ID.

Adolescent↗
PubMed2001

Prevalence of iron deficiency in 12-mo-old infants from 11 European areas and influence of dietary factors on iron status (Euro-Growth study).

A prospective longitudinal cohort study was performed to assess the prevalence of iron deficiency in European infants at 12 mo of age, and to study the influence of socio-economic status, dietary factors, growth and morbidity on iron status. The cohort consisted of 488 normal term infants from primary healthcare centres in 11 European areas. Assessed were socio-economic variables, dietary intake, anthropometry and morbidity at regular intervals from birth to 12 mo, and haemoglobin, serum ferritin, mean corpuscular volume, transferrin saturation and serum transferrin receptor concentrations at age 12 mo. The prevalence of anaemia was 9.4%, of iron deficiency 7.2%, and of iron deficiency anaemia 2.3%. More than 40% of anaemia was associated with normal iron status and associated with an increased frequency of recent infections. Iron deficiency anaemia was significantly more frequent with low (5.1%) than high socio-economic status (0%). Dietary factors accounted for most of this variation in multiple regression analysis. Early introduction of cows' milk was the strongest negative determinant of iron status. Feeding of iron-fortified formula was the main factor positively influencing iron status. Other dietary factors, including breastfeeding, did not play a significant role as determinants of iron status at age 12 mo. Conclusion. Iron deficiency anaemia is present in 2.3% of 12-mo-old European infants. The prevalence of iron deficiency anaemia varies strongly with socio-economic status. Avoidance of cows' milk feeding during the first year of life is the key measure in the prevention of iron deficiency.

Analysis of Variance↗
PubMed2001

Fatty acid composition of plasma lipids in healthy Portuguese children: is the Mediterranean diet disappearing?

BACKGROUND: Adults and children in Mediterranean countries are believed to consume a Mediterranean-type diet which is higher in monounsaturated and n-3 polyunsaturated fatty acids than compared to central and northern parts of Europe and has preventive effects for cardiovascular risks. SUBJECTS AND METHODS: In preschool children from Porto, Portugal (n = 35) and Munich, Germany (n = 18) we determined the plasma phospholipid fatty acid composition considered as a biomarker for dietary fat intake. RESULTS: The plasma phospholipid contents of total saturated fatty acids are similar in both groups, but the Portuguese children have lower values of monounsaturated and n-3 polyunsaturated fatty acids. The results indicate that the food habits of Portuguese children are even less close to the traditional Mediterranean diet than those of German children. CONCLUSIONS: Efforts should be made to encourage young families as well as manufacturers and distributors of food products in Portugal to emphasize traditional Mediterranean food habits, especially in young children.

Biomarkers↗
PubMed2001

Lipid profile and redox status in high performance rhythmic female teenagers gymnasts.

BACKGROUND: The aim of the present study is to evaluate the lipid profile and some parameters of oxi-redox status in a group of teenage female athletes. All gymnasts of the Portuguese National Team of Rhythmic (n=20) were included in the study. A group of untrained healthy female adolescents, matched for age, was also included (n=28). METHODS: Auxology, nutritional status and body composition were evaluated as well as biological parameters, dietary and training habits. Statistics included descriptive analysis, t-Student and Mann-Whitney for comparative study, and Pearson and Spearman correlations, according to variable distribution. RESULTS: Chronological age was 14.3+/-1.7 and 14.6+/-1,7 years, respectively for gymnasts and untrained adolescents. Gymnasts showed lower body mass index (p<0.001) and fat mass (p<0.001) and also a hypoenergetic diet, with higher supply in protein (p<0.05) and saturated fat (p<0.01). Lipid profile showed higher HDL-cholesterol (p<0.01) and lower apo B values (p<0.001) in gymnasts, compared to untrained. Red blood cell's enzymes studied were higher for transmembrane NADH reductase of ferricyanide (TMR), (p<0.01), methaemoglobin reductase (MetHbRed), (p<0.01), and low-molecular weight protein tyrosine phosphatase (LMW-PTP), (p<0.0001) in untrained adolescents. Susceptibility of LDL to peroxidation (LDL-TBARS) were higher in gymnasts (76.3+/-20.3 microM/l versus 35+/-21.7 microM/l), (p<0.001). Correlations were positive and significant in both gymnasts and untrained, between LDL-TBARS and LDL-cholesterol (r=0.674, p<0.01 and r=0.544, p<0.05 respectively) and apolipoprotein B (r=0.721, p<0.001 and r=0.659, p<0.01, respectively). LDL-TBARS were negative and significatively correlated to TMR (t=-0.608; p<0.01) only in gymnasts. CONCLUSIONS: The authors conclude that the practice of intense physical exercise in rhythmic gymnasts induces a compromise of nutritional status and unbalanced food habits. The intensive exercise also induces not only a protective lipid profile, but also a higher lipid peroxidation. Further prospective studies are important to evaluate the influence of intensive training on atherosclerosis development.

Adolescent↗
PubMed2000

Growth increments and biomineralization process in cephalopod statoliths.

A study on morphological, structural and biochemical composition of Sepia officinalis and Loligo vulgaris statoliths and statocyst endolymph was undertaken with the aim of determining the major factors affecting the deposition process of statolith formation and to clarify the cause for the poor definition of the growth increments in S. officinalis statoliths. It is suggested that the different biochemical composition of the statocyst endolymph found in the two species accounts for distinct statolith crystallisation processes, which results in a different microstructure. This explains the better definition of growth increments in L. vulgaris statoliths comparing with those of S. officinalis. The protein content as well as Ca(2+) and Mg(2+) concentrations in the endolymph are more implicated in growth increments formation than Sr(2+) ion concentration. Moreover, the daily variations of the three factors mentioned, allowed us to formulate a working hypothesis to explain the daily deposition of growth increments: a dark ring (rich in organic matter) is deposited during daylight whereas a light ring (rich in CaCO(3)) during darkness. These results are discussed in the light of alternative hypotheses explaining the deposition mechanisms in statoliths.

Journal Article↗
PubMed2000

Polymerization of lignin fragments contained in a model effluent by polyphenoloxidases and horseradish peroxidase/hydrogen peroxide system*

An effluent containing soluble lignin fragments was treated with potato-polyphenoloxidases (PPO) or horseradish peroxidase/hydrogen peroxide system (HRP/H(2)O(2)). In both cases the reaction was evidenced by the formation of a brown precipitate that was a consequence of the polymerization of lignin fragments. The effect of reaction time, pH, and amount of soluble lignin per unit of enzyme activity on the insolubilization yield was evaluated for PPO-initiated reactions. For HRP-initiated reactions, the amount of H(2)O(2) per unit of enzyme activity was also evaluated. Mathematical models were calculated to predict the insolubilization yield as a function of the significant variables. Based on these models, the insolubilization reaction was optimized and reached maximal values of ca. 50% in both reaction systems. Higher insolubilization yields were not achieved. Chemical characterization of the soluble lignin fragments indicated that the insolubilization yield could not be improved, because the lignin fragments had limited amounts of free phenolic substructures available for the initial steps of the polymerization reaction.

Journal Article↗
PubMed2000

Regulation of high affinity taurine transport in goldfish and rat retinal cells.

Adaptive regulation and modulation by phosphorylation are mechanisms by which some cells control taurine transport. Goldfish and rat retinal cells were incubated with the activator of protein kinase C, phorbol 12,13-dibutyrate (PDBu), or the inhibitor of protein phosphatases, okadaic acid (OKA). OKA, 1 nM, inhibited the uptake of taurine at short period of incubation in goldfish retinal cells, and at low concentrations in rat retinal cells incubated with the inhibitor for 1 h. PDBu treatment did not produce significant effects. Isolated Müller cells from the goldfish retina presented a clear adaptive regulation and a decrease of taurine uptake by increasing phosphorylation either by the stimulation of PKC with PDBu or the inhibition of phosphatases with OKA.

Animals↗
PubMed2000

Modulation of taurine uptake in the goldfish retina and axonal transport to the tectum. Effect of crushing the optic nerve or axotomy.

Although there are a great number of studies concerning the uptake of taurine in several tissues, the regulation of taurine transport has not been studied in the retina after lesioning the optic nerve. In the present study, isolated retinal cells of the goldfish retina were used either immediatly after cell suspension or in culture. The high-affinity transport system of [3H]taurine in these cells was sodium-, temperature- and energy-dependent, and was inhibited by hypotaurine and beta-alanine, but not by gamma-aminobutyric acid. There was a decrease in the maximal velocity (Vmax) without modifications in the substrate affinity (Km) after optic axotomy. These changes were mantained for up to 15 days after the lesion. The results might be the summation of mechanisms for providing extracellular taurine to be taken up by other retinal cells or eye structures, or regulation by the substrate taurine, which increases after lesioning the optic nerve. The in vivo accumulation of [3H]taurine in the retina after intraocular injection of [3H]taurine was affected by crushing the optic nerve or by axotomy. A progressive retinal decrease in taurine transport was observed after crushing the optic nerve, starting at 7 hours after surgery on the nerve. The uptake of [3H]taurine by the tectum was compensated in the animals that were subjected to crushing of the optic nerve, since the concentration of [3H]taurine was only different from the control value 24 hours after the lesion, indicating an efficient transport by the remaining axons. On the contrary, the low levels of [3H]taurine in the tectum after axotomy might be an index of the non-axonal origin of taurine in the tectum. Axonal transport was illustrated by the differential presence of [3H]taurine in the intact or crushed optic nerve. The uptake of [3H]taurine into retinal cells in culture in the absence or in the presence of taurine might indicate the existence of an adaptive regulation of taurine transport in this tissue, however taurine transport probably differentially occurs in specific populations of retinal cells. The use of a purified preparation of cells might be useful for future studies on the modulation of taurine transport by taurine in the retina and its role during regeneration.

Animals↗
PubMed2000

Aggregata sagittata n. sp. (Apicomplexa: Aggregatidae), a coccidian parasite from the European flying squid Todarodes sagittatus (Mollusca: Cephalopoda).

A new species of the coccidian genus Aggregata Frenzel, 1885 (Apicomplexa, Aggregatidae) is described from the digestive tract of Todarodes sagittatus (Lamarck), an ommastrephid squid that lives in temperate waters in the northeastern Atlantic Ocean. Using light microscopy. oöcysts were 225-333 microm in length and 220-323 microm in width. Each oöcyst contained 600-1,000 sporocysts. Sporocysts were 16-18 microm in length and 15-17 microm in width, with a smooth surface and thick wall. Each sporocyst contained 4-8 sporozoites each with a length of 11-13 microm. This paper presents the description of a new Agregata species in a nerito-oceanic flying squid. Moreover. it extends the distribution of Aggregata to oceanic cephalopod host species. A. sagittata represents the third named species in the genus Aggregata in European waters and the seventh worldwide.

Animals↗
PubMed2000

Acid phosphatase, genetic polymorphism and cardiovascular risk factors in a pediatric population.

BACKGROUND: Although the clinical expression of cardiovascular disease usually occurs in adulthood, it is unanimously accepted that atherosclerosis begins in the pediatric age. Because of the early onset of the disease, it is of great importance to screen for major risk factors since pre-school age, especially in risk families. Recent investigations have shown a great interest not only in studying the classic risk factors, but also in the evaluation of oxidative stress and the main antioxidant defense systems. The major cause of this interest is the knowledge of the deleterious effect of reactive oxygen species on lipids, the endothelial membrane of arteries and, finally, on the occurrence of cardiovascular disease. POPULATION AND METHODS: 51 children of both genders, aged 9-12 years, randomly selected from a rural community, were observed. A possible association between low molecular acid phosphatase genetic polymorphism of the erythrocyte and the prooxidant status markers (epinephrine oxidase and low molecular protein phosphotyrosine phosphatase from the erythrocyte), some enzymatic systems of the body antioxidant defense (transmembranar reductase of ferricyanide and metahemoglobin reductase) and finally some intermediate phenotypes of cardiovascular disease (lipid profile and blood pressure) were studied. RESULTS: The study of prooxidant status markers and antioxidant enzymes shows significant differences for acid phosphatase and epinephrine oxidase activities in relation to low molecular acid phosphatase genetic polymorphism, the highest values observed being in those homozygous to the B allele (p < 0.05). The inter-relation study between variables showed, among other things, a significant inverse correlation between acid phosphatase and transmembrane reductase and a direct correlation between apolipoprotein B, acid phosphatase and metahemoglobin reductase. A positive family history for cardiovascular disease also showed a direct and significant correlation to total cholesterol, LDL-cholesterol and apolipoprotein B. CONCLUSIONS: The polymorphic variants of low molecular acid phosphatase and protein phosphotyrosine phosphatase with greater activity are strongly associated, not with the classic parameters of cardiovascular risk factors, but with oxidative stress indicators, such as low molecular protein phosphotyrosine phosphatase and epinephrine oxidase. Family history indicators of cardiovascular risk are clearly associated, since early ages, to some conventional risk factors, such as lipid profile and blood pressure.

Acid Phosphatase↗
PubMed2000

Phospholipid distribution in murine mammary adenocarcinomas induced by activated neu oncogene.

The aim of this study was to analyze possible changes in the total phospholipid distribution in murine mammary adenocarcinomas induced in transgenic mice by the tissue-specific expression of the neu oncogene, as compared with normal tissues. To understand whether the altered phospholipid profile might be specifically tissue-related to the oncogene expression, phospholipid composition also has been analyzed in liver, kidney, lung, and spleen. The data indicate that only tumor mammary tissues show a drastic increase of the total phospholipid content (P < 0.0001) associated with a significant increment of phosphatidylethanolamine, phosphatidylcholine, and sphingomyelin (P < 0.05). Moreover, gas-chromatography analysis of total phospholipid-derived fatty acids shows a decrease in the percentage content of linoleic acid in tumor tissues, suggesting an altered metabolism of this fatty acid related to the enhanced epithelial proliferation. We conclude that neu transgenic mice provide a good model to clarify the involvement of phospholipids in neu-induced neoplastic transformation and to study in vivo the metabolic pathways related to the intracellular signaling.

Adenocarcinoma↗
PubMed2000

LDL peroxidation in adolescent female gymnasts.

UNLABELLED: Physical exercise may in vivo promote an increase of free radical formation. Low-density lipoproteins (LDL) are highly susceptible to oxidation, probably because of their high polyunsaturated fatty acid content, since lipid oxidation is an important factor in the genesis and development of atherosclerosis. The aim of the present study is to evaluate the effect in a group of adolescent gymnasts, of intense and regular physical exercise on lipid profile and redox status. POPULATION: All members of the Portuguese National Team of Rhythm Gymnastics (1996) (n = 20). METHODS: 1. Clinical evaluation 1.1 Anthropometric evaluation: weight, height, triceps, biceps, subscapular and supra- and supra-iliac skinfolds. NCHS were used as the standard of reference for weight and height, and Frisancho for the sum of skinfolds; 1.2. Evaluation of nutritional status (Quetelet body mass index) and body composition (Durnin and Siri). 2. Evaluation of biological parameters: a blood sample was collected after 12 hours fasting and 24 hours detraining, to evaluate: 2.1 Lipid profile: total cholesterol, high (HDL) and low (LDL) density lipoproteins, triglycerides, apolipoproteins A1 and B, were measured using internationally recommended laboratory methods; 2.2. Plasma trace elements: zinc, copper and selenium, by atomic absorption; 2.3 Red blood cell enzymes; transmembranar reductase (TMR), metahemoglobin reductase (MethaHbRed) and acid phosphatase, by spectrophotometry; 2.4. Redox status: MDA and MDA-LDL were evaluated by spectrophotometry. 3. Evaluation of eating habits: 24 hr recall. RESULTS: Chronological age is 14.3 +/- 1.7 years. Nutritional assessment shows a mean value for height near the 50th percentile (99% +/- 3.8), and low mean values respectively for BMI (89.3% +/- 9) and sum of triceps and subscapular skinfolds (51.9% +/- 14). Study of lipid profile shows low mean values for total cholesterol (162.3 mg/dl +/- 27.7) LDL-cholesterol (87.6 mg/dl +/- 22.6) and Apo B (64.4 mg/dl +/- 11.5), but high values for HDL-cholesterol (61.3 mg/dl +/- 14.5) and Apo A1 (173.1 mg/dl +/- 25.1). We observe higher values for total cholesterol and LDL-cholesterol in those with lower Cu plasmatic levels. We also observe a negative significative correlation between MDA-LDL and Zn (r = -0.469), Cu (r = -0.524) and RTM (r = -0.608). CONCLUSIONS: The AA concluded that in this group of gymnasts intense physical exercise induces, a favorable lipid profile, but a clear susceptibility to LDL peroxidation in those with lower plasma Cu and Zn values. It is possible that the negative correlation observed between MDA-LDL and TMR is caused by higher consumption of TMR induced by the action of exercise on the oxidative system.

Adolescent↗
PubMed1999

Allozyme differentiation in the cuttlefish Sepia officinalis (Mollusca: cephalopoda) from the NE Atlantic and Mediterranean.

The Atlantic-Mediterranean area has recently been proposed as a new phylogeographical area on the basis of concordance of genetic differentiation patterns observed in several marine species. However, additional taxa need to be studied to establish the phylogeographical relationship between the Atlantic and Mediterranean. Eleven samples of the cuttlefish Sepia officinalis around the Iberian Peninsula, one from the Canary Islands, and another from Fiumicino (Italy) were screened for 33 allozyme loci. Genetic variability was low in all samples (He between 0.022 and 0. 076). Intersample genetic differentiation was high (FST=0.220), mainly because of genetic variation in the non-Iberian samples. One locus (PEPD*), diagnostic between the Italian sample and all others, suggests the possible existence of hitherto unrecognized species or subspecies of Sepia in the Mediterranean Sea. The 11 Iberian samples exhibited moderate genetic differentiation (FST=0.100), which could be explained on the basis of genetic differentiation between Atlantic and Mediterranean samples. Significant clines in allele frequencies were observed for five out of six polymorphic loci. These results support a model of secondary intergradation (i.e. secondary contact of populations that were previously differentiated in isolation) similar to that previously proposed for other marine species from the Atlantic-Mediterranean area.

Animals↗
PubMed1999

Essential arterial hypertension and stone disease.

BACKGROUND: Cross-sectional studies have shown that nephrolithiasis is more frequently found in hypertensive patients than in normotensive subjects, but the pathogenic link between hypertension and stone disease is still not clear. METHODS: Between 1984 and 1991, we studied the baseline stone risk profile, including supersaturation of lithogenic salts, in 132 patients with stable essential hypertension (diastolic blood pressure of more than 95 mm Hg) without stone disease and 135 normotensive subjects (diastolic blood pressure less than 85 mm Hg) without stone disease who were matched for age and sex (controls). Subsequently, both controls and hypertensives were followed up for at least five years to check on the eventual formation of kidney stones. RESULTS: Baseline urine levels in hypertensive males were different from that of normotensive males with regards to calcium (263 vs. 199 mg/day), magnesium (100 vs. 85 mg/day), uric acid (707 vs. 586 mg/day), and oxalate (34.8 vs. 26.5 mg/day). Moreover, the urine of hypertensive males was more supersaturated for calcium oxalate (8.9 vs. 6.1) and calcium phosphate (1.39 vs. 0.74). Baseline urine levels in hypertensive females were different from that of normotensive females with regards to calcium (212 vs. 154 mg/day), phosphorus (696 vs. 614 mg/day), and oxalate (26.2 vs. 21.7 mg/day), and the urine of hypertensive females was more supersaturated for calcium oxalate (7.1 vs. 4.8). These urinary alterations were only partially dependent on the greater body mass index in hypertensive patients. During the follow-up, 19 out of 132 hypertensive patients and 4 out of 135 normotensive patients had stone episodes (14.3 vs. 2.9%, chi-square 11.07, P = 0.001; odds ratio 5.5, 95% CI, 1.82 to 16.66). Of the 19 stone-former hypertensive patients, 12 formed calcium calculi, 5 formed uric acid calculi, and 2 formed nondetermined calculi. Of the urinary factors for lithogenous risk, those with the greatest predictive value were supersaturation of calcium oxalate for calcium calculi and uric acid supersaturation for uric acid calculi. CONCLUSIONS: A significant percentage of hypertensive subjects has a greater risk of renal stone formation, especially when hypertension is associated with excessive body weight. Higher oxaluria and calciuria as well as supersaturation of calcium oxalate and uric acid appear to be the most important factors. Excessive weight and consumption of salt and animal proteins may also play an important role.

Adult↗
PubMed1999

Relationship between supersaturation and calcium oxalate crystallization in normals and idiopathic calcium oxalate stone formers.

BACKGROUND: In an earlier study on recurrent CaOx stone formers with no detectable abnormalities, we found that the urine of these subjects had a lower tolerance to oxalate load than controls and that the removal of urinary macromolecules with a molecular weight greater than 10,000 D improved their tolerance to oxalate. METHODS: The effects on CaOx crystallization of reduced urinary supersaturation of calcium oxalate (CaOx), induced by night water load, were studied in 12 normal males and in 15 male OxCa stone formers who were free from urinary metabolic abnormalities. The effect of the macromolecules, purified and retrieved from the natural and diluted urine, were analyzed in a metastable solution of CaOx. RESULTS: The water load caused an increase in urine volume (from 307 +/- 111 to 572 +/- 322 ml/8 hr, P = 0.014 in normal subjects, and from 266 +/- 92 to 518 +/- 208 ml/8 hr, P = 0.001 in the stone formers) and a concomitant reduction of the relative CaOx supersaturation (from 8.7 +/- 2.5 to 5.1 +/- 2.5 ml/8 hr, P = 0.001 in normal subjects, and from 10.4 +/- 3.5 to 5.0 +/- 2.7 ml/8 hr, P = 0.001 in the stone formers). The decrease in CaOx supersaturation was accompanied by an increase of the permissible increment in oxalate, both in normal subjects (from 43.8 +/- 10.1 to 67.2 +/- 30. 3 mg/liter, P = 0.018) and in the stone formers (from 25.7 +/- 9.4 to 43.7 +/- 17.1 mg/liter, P = 0.0001), without any significant variations of the upper limit of metastability for CaOx (from 21.6 +/- 5.3 to 20.5 +/- 4.2 mg/liter in normal subjects, and from 18.7 +/- 4.5 to 17.1 +/- 3.7 mg/liter in the stone formers). The inhibitory effect of urinary macromolecules with molecular weight greater than 10,000 Daltons did not undergo any change when the latter were recovered from concentrated or diluted urine, either in normal subjects or in the stone formers. CONCLUSIONS: Reduced CaOx supersaturation by means of water load has a protective effect with regards to CaOx crystallization in subjects who do not present any of the common urinary stone risk factors.

Adult↗