Biomedical subjects

R Pires

Publications and source records attributed to R Pires.

22 records · Page 2Linked to original sources

PubMed1991

Non-immune VH-binding specificity of human protein Fv.

The specificity of human F(ab)-binding Protein Fv (previously called Protein F), a sialoprotein released into the digestive tract mainly during hepatitis, was investigated with fragments or chains of monoclonal immunoglobulins. Protein Fv bound an unreduced H-chain dimer of a monoclonal human IgA2m(1) molecule but neither the corresponding L-chain dimer, nor several Bence-Jones molecules. Using enzymatic subfragments of F(ab)mu, or F(ab')2 gamma, a significant binding was observed with Fv fragments (VH + VL), while Fb fragments (CH1 + CL) were inactive. Taken altogether, these results prove that the structure recognized by Protein Fv is located in the VH domain. This structure probably involves discontinuous epitopes linked by a disulphide bond, which are destroyed by combined reduction and dissociation. Protein Fv does not interfere with the antigen-binding site, since there was no reciprocal inhibition with the antigen-antibody reaction.

Chromatography, High Pressure Liquid↗

PubMed1984

A modified gel filtration technique producing an unusual exclusion volume of IgM: a simple way of preparing monoclonal IgM.

The vast majority of monoclonal IgM proteins is eluted just before the total volume of the column when filtered through G200 Sephadex or S200 Sephacryl gels equilibrated in a 0.005 M phosphate buffer but eluted with 0.05 M phosphate buffer containing 1.7 M NaCl. This unusual behaviour in low-ionic buffer is probably due to the poor solubility of IgM in diluted buffers. It allows a 1-step purification procedure under mild conditions and is suitable for both large and small scale preparations.

Acrylic Resins↗

PubMedDate not supplied

[Organic aciduria: diagnosis in high-risk Brazilian patients]

OBJECTIVE: To determine the prevalence of organic acidurias in high-risk Brazilian patients. METHODS: Laboratory techniques for the detection and quantification of organic acids by gas chromatography/mass spectrometry were implemented in Porto Alegre, Brazil. We investigated 1,480 patients suspected of organic aciduria between January 1994 and June 2000. RESULTS: Seventy three (4.9%) cases of organic acidemias (acidurias) were diagnosed among the tested individuals. In most of these patients, prompt therapy resulted in rapid symptom improvement; these results are completely different from our previous cases diagnosed in other laboratories in Europe and the United States, where several patients died before any measures could be taken. CONCLUSIONS: These results demonstrate the importance of diagnosing organic acidurias in loco even in developing countries, in spite of the extra costs involved.

Journal Article↗

PubMedDate not supplied

[Transient neonatal tyrosinemia: a frequent abnormality]

OBJECTIVE: To evaluate the frequency of transient neonatal tyrosinemia, with or without secondary hyperphenylalaninemia,observed through neonatal screening for metabolic disorders, andthe need of monitoration and intervention with drugs and/or specialdiet in selected cases. METHODS: 457.870 dried blood samples obtained by heel stickfrom 3 to 20 days old babies were qualitatively evaluated by aminoacid thin-layer chromatography. Positive cases were quantitativelyconfirmed in serum samples by fluorimetric measurement of tyrosineand phenylalanine. RESULTS: 1.231 dried blood samples displayed positive resultsfor tyrosine in the cromatographic evaluation. The fluorimetricserum analysis disclosed normal levels of tyrosine and phenylalaninein 822 patients. The remained 409 patients showed hightyrosine levels and were placed in three groups according to thetyrosine concentration. In 118 of these cases serum phenylalaninewas also increased. CONCLUCIONS: Transient neonatal tyrosinemia is a very frequentdisorder in neonates (1/372); in some cases very high levels werefound, not only of tyrosine but also phenylalanine. As this findingis not yet accepted as absolutely harmless, the monitoration of thissituation and the use of measures to lower the tyrosine and phenylalaninelevels should be considered by the pediatrician.

Journal Article↗