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Biomedical subjects

L M de Carvalho

Publications and source records attributed to L M de Carvalho.

7 recordsLinked to original sources
PubMed2004

Interaction of aluminium ions with some amino acids present in human blood.

The interaction of aluminium with some amino acids present in human blood was studied combining ion-chromatography (IC), atomic absorption spectrometry (AAS) and ultrafiltration (UF) techniques. An IC system for simultaneous determination of ornithine, lysine, glutamic acid, aspartic acid and tyrosine was developed. By adding aluminium to standard solutions of the amino acids and keeping the pH at 6 and 7 it was possible to verify that aluminium caused a reduction on the amino acid chromatographic signals. Similar experiment, carried out for copper showed the same behaviour (with different percentage of signal reductions) and validated the results for aluminium, considering that the interaction Cu-amino acid is well-established. The AAS analysis of sample fractions (500 microl) after the IC separation showed that aluminium (as copper as well) is not present in the fractions in which the amino acid peaks appear in the chromatogram. These approaches carried out with serum samples after UF showed that part of the "free" fraction of serum aluminium is distributed, besides other ligands, among these amino acids. It was found that in serum the affinity for aluminium followed the sequence Lys>Orn>Tyr>Glu approximately Asp.

Aluminum↗
PubMed2001

HPLC-based method using sample pre-column clean-up for the determination of methanethiol and ethanethiol in parenteral amino acid solutions.

A method has been developed for the chromatographic determination of methanethiol (MT) and ethanethiol (ET) as contaminants in amino acid parenteral nutrition (PN) solutions. The clean-up of the samples before chromatographic analysis was investigated by solid-phase extraction (SPE) on pre-columns filled with polyethylene powder (PE), aluminium oxide (AlOx), silica (SiOx), or polyurethane foam (PUF) as adsorbents. The thiols were more efficiently separated from the matrices by SPE on PUF pre-columns. Simultaneous derivatization and elution with DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) enabled further discrimination between MT and ET by reversed-phase HPLC with spectrophotometric detection. The retention times for the derivatized MT and ET species were 12.5 and 23.0 min, respectively. Recoveries from spiked PN samples were calculated to be approximately 90%, and the MT and ET content of commercial PN solutions was determined using the methodology described. Detection limits of 15 and 10 microg L(-1) were calculated for MT and ET, respectively.

Aluminum Oxide↗
PubMed1998

Cyanide determination in biological fluids using a microdiffusion method with a flow system and polarographic detection.

The report describes a method for the automated polarographic determination of cyanide as tetracyanonickelate (II) anion complex in a gas-diffusion flow system. The volatile cyanide, existing in whole blood, plasma and urine samples, was measured after gas-diffusion using 8 x 10-5 mol l-1 hexaaminenickel solution as acceptor. The linear range of calibration, for measurements at the hanging mercury-drop electrode (HMDE), was from 0.1 to 2.0 micrograms cyanide with r = 0.998. The RSD was, respectively, 3.4 and 1.2% (n = 5) for 0.4 microgram cyanide measured with and without the flow-system configuration. Detection limits of 7.4 microgram l-1 were calculated using the flow system and the method was compared with the classical method using Cavet flasks. Parameters that affect the cyanide determination in the proposed method, such as acceptor solution, pH, flow rate and temperature, were investigated.

Cyanides↗
PubMedDate not supplied

Sulfur speciation by capillary zone electrophoresis: conditions for sulfite stabilization and determination in the presence of sulfate, thiosulfate and peroxodisulfate.

Capillary zone electrophoresis (CZE) was used for the separation of the sulfur species SO3(2-), SO4(2-), S2O(3-) and S2O8(2-). Using an electrolyte system with 9.5 mmol L(-1) potassium chromate as UV-absorbing probe and 1 mmol L(-1) diethylenetriamine (DETA) as electroosmotic flow modifier, various possibilities for the stabilization of sulfite and electrophoretic separation of the sulfur anions were investigated. By adding 5% propanol as a stabilizer to both the working electrolyte and the sample solution, a good stabilization for sulfite and a separation of the sulfur anions in a short analysis time (4 min) was achieved. The advantages by using propanol instead of other stabilizers often used in analytical techniques are discussed. The electrophoretic separation of the sulfur anions was optimized with respect to the pH of the working electrolyte and concentration of the electroosmotic flow modifier (DETA). The detection limits achieved for SO3(2-), SO4(2-), S2O3(2-) and S2O8(2-) were 0.35, 0.25, 0.78 and 0.80 mg L(-1), respectively.

Journal Article↗
PubMedDate not supplied

Anticardiolipin antibody in recurrent spontaneous aborting and fertile women.

OBJECTIVE: To determine the association between the presence of anticardiolipin antibody and a history of recurrent spontaneous abortion. STUDY DESIGN: Clinical controlled study. LOCATION: Department of Gynecology and Obstetrics-University of Campinas (UNICAMP). SUBJECTS: 52 individuals with recurrent spontaneous abortion were included in Group 1 and 104 individuals with at least one live born child in Group 2. Elapsed time from last delivery to blood sampling varied from six months to two years. METHOD: Between November 1993 and November 1994, patients' blood samples were screened for anticardiolipin antibody by ELISA, as described by Triplett, Barna and Unger (1993). ANALYSIS: Chi-square and Fisher's Exact tests were used for statistical analysis. Student's "t" test was used to compare the means. RESULTS: There was no statistical difference in the presence of the anticardiolipin antibody between Group 1 (zero and 2.9%) and Group 2 (7.7 and 5.8%). CONCLUSION: There was no association between the presence of anticardiolipin antibody and recurrent spontaneous abortion.

Abortion, Habitual↗
PubMedDate not supplied

[Vertebral osteomyelitis in children].

Vertebral osteomyelitis is an uncommon disease in children, presenting with signs and symptoms that, at least initially, make a correct diagnosis difficult to be achieved. The authors report five cases of vertebral osteomyelitis in children, describing its clinical and laboratory peculiarities. The usefulness of the different radiologic studies for the diagnosis and follow up of these patients is discussed. We confirm previous reports according to which, with adequate clinical and therapeutic management, the prognosis is good for most patients.

English Abstract↗