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Biomedical subjects

C Centeno

Publications and source records attributed to C Centeno.

28 records · Page 2Linked to original sources
PubMed1996

Determination of trace lithium in biological fluids using graphite furnace atomic absorption spectrophotometry: variability of urine matrices circumvented by cation exchange solid phase extraction.

A graphite furnace atomic absorption spectrometry method has been developed for the quantitative determination of submicromolar endogenous concentration of lithium in human plasma and urine using pyrolitically-coated graphite tubes in combination with ammonium nitrate matrix modification. This latter treatment could not completely abolish the interferences caused by the matrix, notably in urine samples. The variability of the urinary matrices required an additional standardization procedure by solid-phase extraction on strongly acidic cation exchange cartridges. Matrix-matched samples were used for the establishment of calibration curves with the addition-calibration method. Calibration curves were linear up to 0.72 mumol/l (1.0 > r2 > 0.99). The described method enables accurate measurements of trace-lithium in biological samples at concentrations down to 0.03 mumol/l with intra- and inter-day variabilities < 10%. The method was applied to the determination of trace-lithium levels in urine and plasma samples from healthy individuals enabling the calculation of its fractional excretion (FeLi) (median range 17.3%), a value which reflects the functional capacity of the kidney to reabsorb sodium and water at the proximal tubular portion of the nephron. This sensitive method can thus be used as an investigative and diagnostic tool in various renal pathophysiological conditions, in clinical research, and may also be applied to studies on the trace-lithium status of population in connection with psycho-affective disorders.

Cations↗
PubMed1995

Effect of endotoxin on the angiotensin II receptor in cultured vascular smooth muscle cells.

1. In some tissues, a decrease in the number of cell surface receptors and alterations of the receptor coupling have been proposed as possible mechanisms mediating the deleterious effects of bacterial endotoxin in septic shock. 2. The effects of bacterial lipopolysaccharide (Escherichia coli 0111-B4; LPS) on vascular angiotensin II and vasopressin receptors have been examined in cultured aortic smooth muscle cells (SMC) of the rat by use of radioligand binding techniques. 3. In vascular SMC exposed to 1 micrograms ml-1 endotoxin for 24 h, a significant increase in angiotensin II binding was found. The change in [125I]-angiotensin II binding corresponded to an increase in the number of receptors whereas the affinity of the receptors was not affected by LPS. In contrast, no change in [3H]-vasopressin binding was observed. 4. The pharmacological characterization of angiotensin II binding sites in control and LPS-exposed cells demonstrated that LPS induced an increase in the AT1 subtype of the angiotensin II receptors. Receptor coupling as evaluated by measuring total inositol phosphates was not impaired by LPS. 5. The effect of LPS on the angiotensin II receptor was dose-, time- and protein-synthesis dependent and was associated with an increased expression of the receptor gene. 6. The ability of LPS to increase angiotensin II binding in cultured vascular SMC was independent of the endotoxin induction of NO-synthase. 7. These results suggest that, besides inducing factors such as cytokines and NO-synthase, endotoxin may enhance the expression of cell surface receptors. The surprising increase in angiotensin II binding in LPS exposed VSM cells may represent an attempt by the cells to compensate for the decreased vascular responsiveness. It may also result from a non-specific LPS-related induction of genes.

Angiotensin II↗
PubMed1989

Influence of peas (Pisum sativum) as a dietary ingredient and flavomycin supplementation on the performance and intestinal microflora of broiler chicks.

1. Two experiments were carried out to study the effects of diets containing various concentrations of pea meal (Pisum sativum L.), with or without flavomycin supplementation, on the performance and intestinal microflora of broiler chicks. 2. During the 7 to 28-d period, chicks fed on diets containing 300, 600 and 800 g pea meal/kg consumed more food and gained more weight than chicks receiving a maize-isolated soyabean protein control diet. The addition of flavomycin to the diets had similar effects on the performance of both the control and the pea groups. 3. Pea diets, with and without supplemental flavomycin, had little influence on the composition of intestinal microflora. The counts of enterococci in the small intestine and Clostridium perfringens and coliforms in the caeca of pea-fed chicks exceeded those of control chicks.

Aminoglycosides↗
PubMed1987

[Supplementation of maternal milk with calcium and phosphorus for the feeding of premature neonates weighing 1500 g or less. How long should it be continued?].

Feeding four preterm infants weighing less than or equal to 1,500 g with human milk supplemented with calcium (160-200 mg/kg/day) and phosphorus (80-200 mg/kg/day) until term postmenstrual age was reached, and suitable levels of plasma calcium, phosphorus and alkaline phosphatase and urinary excretion index of calcium and phosphorus were attained. When such a supplementation was suppressed at 38-40 weeks of postmenstrual age a rapid onset of biochemical disturbances was observed: a rise of plasma calcium (p less than 0.025) and alkaline phosphatase (p less than 0.0025) with a decrease of plasma phosphorus (p less than 0.005) and of urinary phosphate excretion (p less than 0.002). Reincorporation to former supplemented regime results in quick recovery of these parameters. Authors can assert that the necessity of calcium and phosphorus supplementation of human milk for less than or equal to 1.500 g preterm infant feeding exceeds the term postmenstrual age if suitable calcium and phosphorus levels are to be obtained.

Alkaline Phosphatase↗
PubMed1986

[Regional organization of a neonatal transportation system].

Organization, operational plans, and initial experience of a Regional Neonatal Transport System is described. The system covers provinces of Bizcaia, and Alava in Northern Spain, with a total of 17,500 annual deliveries. In the first 10 months 31 newborn infants were transported. Their mean birth weight was 2,066 +/- +/- 931 Gm. Ten infants had a birth weight less than 1,500 Gm, and in 22 (71%) of them gestational age was under 37 weeks. Some types of respiratory distress was present in 71% of them, and 25.8% required mechanical ventilation during transport. Hypothermia was present in 36% of the infants at referral center, percentage that decreased to only 9% at their arrival to the NICU. During transport mean body temperature increased from 35.33 +/- 1.07 degrees to 35.84 +/- 0.9 degrees C (p less than 0.01). Infants condition was judged to improve in 13% of them. Overall survival rate was 74.2%, being 80.9% in those weighting from 1,000 to 1,500 Gm. Infants who were hypothermic had a lower survival (45.5%) than those who were not (90%) (p less than 0.05).

Birth Weight↗
PubMed1983

[Isolated isoleucine deficiency in diet therapy of a case of maple syrup urine disease].

A case of maple syrup urine disease is described presenting during diet therapy a clinical picture with predominant cutaneous symptoms attributed to a dietary deficiency. It is believed that probable cause was the coexistence of low serum levels of isoleucine with still elevated levels of leucine. Given the metabolic interrelationship existing between different branch-chained amino acids, an independent dietary correction of each amino acid is recommended.

Acrodermatitis↗
PubMed1981

[Triglycerides and cholesterol esterification during parenteral nutrition of newborn infants (author's transl)].

In a group of 23 newborn infants with necrotizing enterocolitis receiving parenteral nutrition the serum triglyceride levels (347 samples), and the free to esterified cholesterol ratio (188 determinations) were studied. The relationship of both T, and FCH/ECH with bacterial infections were also studied. Mean T level increased significantly with the episodes of infection. In the group of infants with a birth weight less than 1,500 grs. a significantly greater percentage of T levels above 250 mg./dl. than in infants of a greater birth weight is found. FCH/ECH ratio was already abnormal in infants with necrotizing enterocolitis before parenteral nutrition was started. Authors also observed a positive correlation between abnormality of cholesterol esterification and days of parenteral nutrition.

Bacterial Infections↗
PubMedDate not supplied

Rumen effective degradability of amino acids from soybean meal corrected for microbial contamination.

Rumen degradation kinetics and effective degradability of individual amino acids, total analysed amino acids (TAA) and crude protein (CP) of soybean meal were measured on four rumen-cannulated wethers using the nylon bag technique. Microbial contamination of the incubated residues was corrected using a continuous 15N intraruminal infusion and isolated solid associated bacteria as a reference sample. TAA showed a lower soluble fraction (14.9 vs. 20.8%; P < 0.01), a similar insoluble-degradable fraction (79.0 vs. 79.2%) and a higher degradation rate (11.5 vs. 8.4% x h(-1); P < 0.05) than CP. As a consequence, effective degradability was similar for TAA and CP (74.7 vs. 75.7%). Degradability values of individual amino acids varied moderately (range: +/-6% of TAA degradability). Valine, isoleucine, leucine, alanine, aspartic acid and tyrosine showed significantly lower degradability than TAA, while the opposite effect was observed for histidine, threonine and glutamic acid. Degradability of individual amino acids was related to their soluble fraction (r = 0.877; P<0.001).

Amino Acids↗