Search PubMed⌕ Search

Biomedical subjects

J A Prieto

Publications and source records attributed to J A Prieto.

At least 19 recordsLinked to original sources
PubMed2006

Effect of docosahexaenoic acid administration on plasma lipid profile and metabolic parameters of children with methylmalonic acidaemia.

AIM: To evaluate the effect of administration of docosahexaenoic acid (DHA) on dyslipidaemia, plasma fatty acid composition and metabolic parameters of children with isolated methylmalonic acidaemia (MMA) (McKusick 25100). METHODS: Four children (3 male, 1 female) with MMA (mut(0)), participated in a crossover, randomized study of DHA administration (25 mg/kg per day, divided into three daily doses). The control group comprised 56 healthy children, aged 10+/- 2.7 years, (51 male, 5 female), who were followed in our clinic owing to possible familial risk of cardiovascular disease. RESULTS: The comparison of plasma fatty acid composition of children with MMA versus control children demonstrated that the patients had significantly higher values for oleic acid (p = 0.004) and linolenic acid (p = 0.008). No differences were observed in the levels of DHA and arachidonic acid. Plasma concentrations of insulin, glycine, ammonia, total cholesterol and cholesterol fractions did not change with DHA administration. No significant changes were observed in urinary excretion of methylmalonic acid. As expected, the percentage of DHA and n-3 fatty acids in plasma increased significantly after therapy (p = 0.005 and 0.014, respectively). The most remarkable result was a decrease of plasma levels of triglycerides after DHA therapy (p = 0.014). CONCLUSION: As previously found in normal children, dietary supplementation with DHA decreases the triglyceride levels, normalizing the hypertriglyceridaemia of these children without any evidence of short-term adverse effects.

Adolescent↗
PubMed2006

[A randomized single-blind trial of the effects of vitamins C and E in familial hypercholesterolemia].

INTRODUCTION: The aim of this study was to evaluate the effect of antioxidant vitamin C and E administration on dyslipidemia, plasma fatty acid composition, and biochemical inflammatory markers in children with heterozygous familial hypercholesterolemia (FH). PATIENTS: Forty girls and boys with heterozygous FH, aged between 2 and 18 years, and with plasma low-density lipoprotein (LDL)-cholesterol levels higher than 160 mg/dl were studied. METHODS: We performed an open longitudinal randomized trial over a 1-year period. All children followed a dietary intervention according to the National Cholesterol Education Program (NCEP)-1 guidelines and were randomized into two groups. One group (n = 21) received therapy with vitamin C (500 mg twice a day) and vitamin E (400 IU per day). A second group (n = 19) did not receive vitamin therapy. RESULTS: In patients receiving antioxidant vitamins, plasma linoleic acid levels (18:2 omega-6) significantly increased and the essential fatty acid deficiency ratio significantly decreased (Mead/arachidonic acid: 20:4 omega-6/20:3 omega-9). No significant differences were observed in plasma lipid profile, adhesion molecules, or reactive C protein. CONCLUSIONS: Antioxidant vitamin therapy in children with heterozygous FH modifies the plasma fatty acid profile. These modifications are independent of the degree of dyslipidemia and may represent an indicator of reduced cardiovascular risk.

Adolescent↗
PubMed2004

Determination of 5-dodecylsalicylaldoxime and 5-nonylsalicylaldoxime in commercial extractants by high-performance liquid chromatography with photometric detection.

A liquid chromatographic method with photometric detection was developed and validated for the determination of 5-dodecylsalicylaldoxime in the industrial extractants LIX 622 and LIX 860 and 5-nonylsalicylaldoxime in LIX 622N, Acorga PT5050 and Acorga P5100. The limit of detection was 2.18 microg/ml for 5-dodecylsalicylaldoxime and 2.06 microg/ml for 5-nonylsalicylaldoxime. Good linear relations between the areas and the concentration of the standard injected were found in the range of 5-100 microg/ml and reproducibility studies yielded relative standard deviations lower than 6.12% in all the cases.

Chromatography, High Pressure Liquid↗
PubMed2003

Osmotolerance and leavening ability in sweet and frozen sweet dough. Comparative analysis between Torulaspora delbrueckii and Saccharomyces cerevisiae baker's yeast strains.

The response of Saccharomyces cerevisiae and freeze-tolerant Torulaspora delbrueckii strains to osmotic stress and their CO2 production capacity in sweet and frozen-sweet dough has been examined. T. delbrueckii strains, IGC5321 and IGC5323 showed higher leavening ability than Saccharomyces, specially after exposure to hyperosmotic stress of bread dough containing 20% sucrose and 2% salt added. In addition, Torulaspora and especially T. delbrueckii IGC5321 exhibited no loss of CO2 production capacity during freeze-thaw stress. Overall, these results appeared to indicate that Torulaspora cells are more tolerant than Saccharomyces to osmotic stress of bread dough. This trait correlated with a low invertase activity, a slow rate of trehalose mobilisation and the ability to respond rapidly to osmotic stress. Growth behaviour on high osmotic synthetic media was also examined. Cells of the IGC5321 strain showed intrinsic osmotolerance and ion toxicity resistance. However, T. delbrueckii IGC5323 exhibited a clear phenotype of osmosensitivity. Hence, this characteristic may not be essential or the only determinant for leavening ability in salted high-sugar dough.

Bread↗
PubMed2001

Capillary zone electrophoresis applied to the determination of the angiotensin-converting enzyme inhibitor cilazapril and its active metabolite in pharmaceuticals and urine.

A capillary zone electrophoresis method has been developed for the quantitation of antihypertensive drug cilazapril and its active metabolite cilazaprilat in pharmaceuticals and urine. The separation of the compounds was performed in a fused-silica capillary filled with the running electrolyte, which consisted of a 60 mM borate buffer solution at pH 9.5. Under the optimized experimental conditions, the separation took less than 5 min. The analysis of urine samples required a previous solid-phase extraction step using C8 cartridges. The method was successfully applied to the determination of the drug and its metabolite in urine samples obtained from three hypertensive patients (detection limits of 115 ng ml(-1) for cilazaprilat and 125 ng ml(-1) for cilazapril) and to pharmaceutical dosage forms. The method was validated in terms of reproducibility, linearity and accuracy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Determination of the antihypertensive drug cilazapril and its active metabolite cilazaprilat in pharmaceuticals and urine by solid-phase extraction and high-performance liquid chromatography with photometric detection.

A liquid chromatographic method with photometric detection for the determination of cilazapril and its active metabolite and degradation product cilazaprilat in urine and pharmaceuticals has been developed. The chromatographic method consisted of a microBondapak C18 column maintained at 30+/-0.2 degrees C, using a mixture of methanol-10 mM phosphoric acid (50:50 v/v) as mobile phase at a flow-rate of 1.0 ml/min. Enalapril maleate was used as internal standard. The detection was performed at a wavelength of 206 nm. A study of the retention of cilazapril and cilazaprilat using solid-liquid extraction has been carried out in order to optimise the clean-up procedure for urine samples, which consisted of a solid-liquid extraction using C(R) cartridges. Recoveries greater than 85% are obtained for both compounds. The method was sensitive, precise and accurate enough to be applied to the determination of urine samples obtained from three hypertensive patients up to 24 h after intake of a therapeutic dose (detection limit of 70 ng/ml for cilazapril and cilazaprilat in urine). A comparison of the method developed using photometric and amperometric detection has been carried out.

Antihypertensive Agents↗
PubMed2001

The Saccharomyces cerevisiae aldose reductase is implied in the metabolism of methylglyoxal in response to stress conditions.

The enzyme aldose reductase plays an important role in the osmo-protection mechanism of diverse organisms. Here, we show that yeast aldose reductase is encoded by the GRE3 gene. Expression of GRE3 is carbon-source independent and up-regulated by different stress conditions, such as NaCl, H2O2, 39 degrees C and carbon starvation. Measurements of enzyme activity and intracellular sorbitol in wild-type cells also indicate that yeast aldose reductase is stress-regulated. Overexpression of GRE3 increases methylglyoxal tolerance in Saccharomyces cerevisiae. Furthermore, high expression of GRE3 complements the deficiency of the glyoxalase system of a glo1delta mutant strain. Consistent with this, in vitro and in vivo assays of yeast aldose reductase activity indicate that methylglyoxal is an endogenous substrate of aldose reductase. Furthermore, addition of NaCl or H2O2 to exponential-phase cells triggers an initial transient increase in the intracellular level of methylglyoxal, which is dependent on the Gre3p and Glo1p function. These observations indicate that the metabolism of methylglyoxal is stimulated under stress conditions; and they support a methylglyoxal degradative pathway, in which this compound is metabolised by the action of aldose reductase.

Aldehyde Reductase↗
PubMed2001

Solid-phase extraction and high-performance liquid chromatography applied to the determination of quinapril and its metabolite quinaprilat in urine.

Quinapril is an antihypertensive drug that belongs to the family of angiotensin-converting enzyme inhibitors. It is metabolized to quinaprilat, which is the compound that is really responsible for the therapeutic action. In this study, a rapid and simple liquid chromatographic method with photometric detection is described and applied to the determination of quinapril and quinaprilat in urine. The cleanup procedure for the urine samples consists of a solid-liquid extraction using C8 cartridges. Under these conditions, both compounds and the internal standard (enalapril maleate) are separated in less than 9 min. Recoveries for quinapril and quinaprilat are greater than 80%. The method is sensitive enough (detection limit of 60 ng/mL for quinapril and 50 ng/mL for quinaprilat) to be applied for the determination of quinapril and quinaprilat in urine samples obtained from four hypertensive patients after the intake of a therapeutic dose.

Antihypertensive Agents↗
PubMed2000

Isolation, purification, and characterization of a cold-active lipase from Aspergillus nidulans.

Aspergillus nidulans WG312 strain secreted lipase activity when cultured in liquid media with olive oil as carbon source. Highest lipase productivity was found when the mycelium was grown at 30 degrees C in a rich medium. The new enzyme was purified to homogeneity from the extracellular culture of A. nidulans by phenyl-Sepharose chromatography and affinity binding on linolenic acid-agarose. The lipase was monomeric with an apparent M(r) of 29 kDa and a pI of 4.85 and showed no glycosylation. Kinetic of enzyme activity versus substrate concentration showed a typical lipase behavior, with K(M) and K(cat) values of 0.28 mM and 494 s(-)(1) and 0.30 mM and 320 s(-)(1) for the isotropic solution and for the turbid emulsion, respectively. All glycerides assayed were hydrolyzed efficiently by the enzyme, but this showed preference toward esters of short- and middle-chain fatty acids. The optimum temperature and pH for the lipolytic activity were 40 degrees C and 6.5, with high activity in the range 0-20 degrees C and reduced thermal stability.

Aspergillus nidulans↗
PubMed1999

Construction of a lactose-assimilating strain of baker's yeast.

A recombinant strain of baker's yeast has been constructed which can assimilate lactose efficiently. This strain has been designed to allow its propagation in whey, the byproduct resulting from cheese-making. The ability to metabolize lactose is conferred by the functional expression of two genes from Kluyveromyces lactis, LAC12 and LAC4, which encode a lactose permease and a beta-galactosidase, respectively. To make the recombinant strain more acceptable for its use in bread-making, the genetic transformation of the host baker's yeast was carried out with linear fragments of DNA of defined sequence, carrying as the only heterologous material the coding regions of the two K. lactis genes. Growth of the new strain on cheese whey affected neither the quality of bread nor the yeast gassing power. The significance of the newly developed strain is two-fold: it affords a cheap alternative to the procedure generally used for the propagation of baker's yeast, and it offers a profitable use for cheese whey.

Lactose↗
PubMed1999

Engineering baker's yeast: room for improvement.

Bread making is one of the oldest food-manufacturing processes. However, it is only in the past few years that recombinant-DNA technology has led to dramatic changes in formulation, ingredients or processing conditions. New strains of baker's yeast that produce CO2 more rapidly, are more resistant to stress or produce proteins or metabolites that can modify bread flavour, dough rheology or shelf-life are now emerging.

Cellulose↗
PubMed1999

Expression of LIP1 and LIP2 genes from Geotrichum species in Baker's yeast strains and their application to the bread-making process.

Lipolytic baker's yeast strains able to produce extracellular active lipase have been constructed by transformation with plasmids containing the LIP1 and LIP2 genes from Geotrichum sp. under the control of the Saccharomyces cerevisiae actin promoter (pACT1). Lipase productivity differed between both constructs, YEpACT-LIP1-t and YEpACT-LIP2-t, being higher for the strain bearing the LIP2 gene in all culture media tested. This result appeared not to be the consequence of a defect in the transcription of the LIP1 gene as revealed by Northern blot analysis. Replacing the signal sequence of LIP1 by that of LIP2 in the YEpACT-LIP1-t plasmid enhanced significantly the secretion of lipase 1, but the levels of lipase activity were still lower than those found for the YEpACT-LIP2-t transformant. Recombinant lipase 2 protein produced by baker's yeast exhibited biochemical properties similar to those of the natural enzyme. Fermented dough prepared with YEpACT-LIP2-t-carrying cells rendered a bread with a higher loaf volume and a more uniform crumb structure than that prepared with control yeast. These effects were stronger by the addition in the bread dough formulas of a preferment enriched in recombinant lipase 2.

Bread↗
PubMed1998

Quantitative determination of the angiotensin-converting enzyme inhibitor cilazapril and its active metabolite cilazaprilat in pharmaceuticals and urine by high-performance liquid chromatography with amperometric detection.

A rapid and simple high-performance liquid chromatographic method with amperometric detection has been developed for the quantitation of cilazapril and its active metabolite and degradation product cilazaprilat in urine and tablets. The chromatographic system consisted of a microBondapak C18 column, using a mixture of methanol-5 mM phosphoric acid (50:50, v/v) as mobile phase, which was pumped at a flow-rate of 1.0 ml/min. The column was kept at a constant temperature of (40+/-0.2) degrees C. Detection was performed using a glassy carbon electrode at a potential of 1350 mV. Sample preparation for urine consisted of a solid-phase extraction using C8 cartridges. This procedure allowed recoveries greater than 85% for both compounds. The method proved to be accurate, precise and sensitive enough to be applied to pharmacokinetic studies and it has been applied to urine samples obtained from four hypertensive patients (detection limit of 50 ng/ml for cilazapril and 40 ng/ml for cilazaprilat in urine). Results were in good agreement with pharmacokinetic data.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Hexokinase PII has a double cytosolic-nuclear localisation in Saccharomyces cerevisiae.

We describe here that the HXK2 gene product, isoenzyme PII of hexokinase, is located in both the nucleus and the cytoplasm of Saccharomyces cerevisiae cells. This conclusion is supported by assays of hexokinase-specific activity in isolated nuclei from wild-type and hxk1lhxk2 double mutant strains, by immunoblot experiments using anti-Hxk2 antibodies and by observation of the fluorescence distribution of a Hxk2-GFP fusion protein in cells transformed with the HXK2::gfp gene.

Cell Fractionation↗
PubMed1998

Carbon source-dependent phosphorylation of hexokinase PII and its role in the glucose-signaling response in yeast.

The HXK2 gene is required for a variety of regulatory effects leading to an adaptation for fermentative metabolism in Saccharomyces cerevisiae. However, the molecular basis of the specific role of Hxk2p in these effects is still unclear. One important feature in order to understand the physiological function of hexokinase PH is that it is a phosphoprotein, since protein phosphorylation is essential in most metabolic signal transductions in eukaryotic cells. Here we show that Hxk2p exists in vivo in a dimeric-monomeric equilibrium which is affected by phosphorylation. Only the monomeric form appears phosphorylated, whereas the dimer does not. The reversible phosphorylation of Hxk2p is carbon source dependent, being more extensive on poor carbon sources such as galactose, raffinose, and ethanol. In vivo dephosphorylation of Hxk2p is promoted after addition of glucose. This effect is absent in glucose repression mutants cat80/grr1, hex2/reg1, and cid1/glc7. Treatment of a glucose crude extract from cid1-226 (glc7-T152K) mutant cells with lambda-phosphatase drastically reduces the presence of phosphoprotein, suggesting that CID1/GLC7 phosphatase together with its regulatory HEX2/REG1 subunit are involved in the dephosphorylation of the Hxk2p monomer. An HXK2 mutation encoding a serine-to-alanine change at position 15 [HXK2 (S15A)] was to clarify the in vivo function of the phosphorylation of hexokinase PII. In this mutant, where the Hxk2 protein is unable to undergo phosphorylation, the cells could not provide glucose repression of invertase. Glucose induction of HXT gene expression is also affected in cells expressing the mutated enzyme. Although we cannot rule out a defect in the metabolic state of the cell as the origin of these phenomena, our results suggest that the phosphorylation of hexokinase is essential in vivo for glucose signal transduction.

Adaptation, Biological↗
PubMed1997

Neutrophil activation in preeclampsia. Are defensins and lactoferrin elevated in preeclamptic patients?

OBJECTIVE: To determine if human defensins and lactoferrin, both markers of neutrophil activation, are elevated in preeclamptic plasma. STUDY DESIGN: Blood samples were obtained from 18 preeclamptic and 29 normal pregnant women in the third trimester. Demographic and clinical data were obtained from the medical record. No patient had evidence of labor and/or infection when blood was drawn. Preeclamptic patients were defined by elevated blood pressure, 140/90 mm Hg, proteinuria of > 300 mg in a 24-hour collection and hyperuricemia. Human defensins and lactoferrin were measured by enzyme immunoassay of plasma samples diluted 1:100 and 1:10, respectively. Standard curve values ranged from 0.25 to 16 ng/mL. Data for human defensins and lactoferrin are presented as median values +/-SE. Statistical analysis included Student's t test for comparison of clinical data, Mann-Whitney U test for comparison of absolute values between groups and Fisher's exact test, when appropriate. RESULTS: There was no difference in age or estimated gestational age between the two groups. There were more nulliparous patients in the preeclamptic group. Human defensin levels were significantly elevated (P = .005) in plasma of preeclamptic patients (25.1 ng/mL +/- 16.2) as compared to normal controls (9.0 ng/mL +/- 8.9). Nine of 18 (50%) preeclamptic patients and 2 of 29 (7%) normal controls had defensin levels above the low point on the standard curve (P = .001). There was no difference in lactoferrin levels between the two groups. CONCLUSION: Our results suggest that preeclampsia is associated with neutrophil activation. The biologic effect of elevated human defensins in preeclamptic plasma remains to be determined.

Adult↗
PubMed1997

Felodipine use in pregnancy. Report of three cases.

BACKGROUND: Calcium channel blockers are effective agents for the management of chronic hypertension and are being used with increasing frequency. If their safety and efficacy during pregnancy can be documented, women can be counseled to continue their antihypertensive agent during pregnancy. To our knowledge, the use of felodipine, a calcium channel blocker of the dihydropyridine group, during pregnancy has not been described. CASES: We report three cases of felodipine use in pregnancy by women with chronic hypertension. CONCLUSION: In women with severe hypertension (diastolic blood pressure > 100 mm Hg) who require pharmacologic treatment of it during pregnancy, felodipine appears to be an acceptable option.

Adult↗