Biomedical subjects
Publications and source records attributed to J Rocha.
Red cell acid phosphatase (ACP1), adenylate kinase 1 (AK1), and aminolevulinate dehydratase (ALAD) polymorphisms were studied in a population sample from Northern Portugal. The gene frequency estimates found were: ACP1*A = 0.2825, ACP1*B = 0.6625, ACP1*C = 0.0547, ACP1*R = 0.0003 (N = 1517); AK1*1 = 0.9778, AK1*2 = 0.0213, AK1*3 = 0.0009 (N = 1081); ALAD*1 = 0.9094, ALAD*2 = 0.0906 (N = 1043).
Isoelectric focusing of human orosomucoid (ORM) was studied following different sample treatment. It is shown that: (i) alkylation with iodoacetamide leads to a drastic change in the isoelectric point (pI) of both ORM1 F2 and ORM2 A gene products and greatly improves the discrimination between ORM1 F1 and ORM1 F2; (ii) previous reduction of the molecule with dithiothreitol partially inhibits the pI transitions with resultant artifactual ORM1 F1F2S patterns that correspond in most cases to F2S phenotypes. With the technique now described, the persistence of three ORM1 gene products was found in only one individual and the segregation analysis is consistent with the existence of a rare ORM1*F2S haplotype.
Standard samples of stream humic and fulvic acids have been studied by high-resolution 13C solid-state NMR. The spectra have been recorded at a high (9.4 T) magnetic field using 1H-13C cross-polarization (CP) and proton high-power decoupling (HPDEC) with fast (up to 15 kHz) magic-angle spinning (MAS). The widths of the spectral lines decrease with increasing spinning rate. This is probably due to the overlap of spinning sidebands with resonances at low speeds and to a more effective averaging of anisotropic broadening at high speeds. However, fast MAS modulates the CP signal intensities, making quantitative analysis very difficult.
Acute encephalopathy is a recognized toxic effect of Cyclosporin A (CsA) in organ transplantation recipients. A 16-year-old girl presented with acute encephalopathy 2 weeks after CsA and methylprednisolone medication for idiopathic uveitis. Magnetic resonance imaging showed cortical and white matter occipital changes, which were not visible 2 months later. With expanding indication for CsA use, an increasing number of neurotoxic cases are to be expected.
Solid-state 27Al NMR spectra of several aluminophosphate molecular sieves have been recorded with conventional magic-angle spinning (MAS), double-rotation (DOR) and quadrupole nutation with fast MAS. Enhanced resolution was obtained in the quadrupole nutation experiment at certain radiofrequency pulse strengths. This extra resolution can be comparable to that attainable using DOR, and does not introduce spinning sidebands.
Genetic polymorphism of serum albumin was demonstrated by isoelectric focusing in wild rabbit populations from Portugal and England. Gene frequencies were estimated to be (1) ALB*1 = 0.47, ALB*2 = 0.49, ALB*3 = 0.04, in Portugal, and (2) ALB*1 = 0.60 and ALB*2 = 0.40, in England. One hundred Portuguese domestic rabbits of mixed breeds were all of ALB 1 type.
A technique for the separation of human alloalbumin variants by means of isoelectric focusing in the presence of 8M urea and 60 mM L-serine is described. The potential usefulness of this technique in the detection and classification of genetic heterogeneity at the albumin locus is demonstrated by the differentiation of three human alloalbumin variants of European origin.
The results of a study on the expression of GPT (glutamate-pyruvate transaminase; E.C. 2.6.1.2) in a child with a partial trisomy of chromosomes 8 and 14 are presented. A gene dosage effect supporting the regional assignment of the GPT locus to 8q24.2----8qter is demonstrated.
The formal genetics of esterase D (EC 3.1.1.1) was studied in family data and mother/child pairs. A general agreement with mendelian expectations was found. However, a significant sex-phenotype association was detected in families from northwestern Portugal as well as in mother/child pairs and family data from southwestern Germany.
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A solid-state nuclear magnetic resonance (NMR) experiment, which provides high-resolution two-dimensional heteronuclear correlation (HETCOR) spectra between 27Al and 31P, is described. The first part of the experiment uses triple-quantum or quintuple-quantum magic-angle spinning (MQMAS) NMR of spin-5/2 nuclei (27Al) to produce an isotropic echo that is unaffected by the second-order quadrupolar broadening. The magnetization is then transferred to the spin-1/2 (31P) nuclei via cross-polarization (CP), resulting in isotropic resolution in both spectral dimensions. To illustrate its usefulness, this method (referred to as MQHETCOR) is applied to two important microporous framework aluminophosphates, hydrated VPI-5 and AIPO4-40.
Factor XIII a subunit (F13A) is the last enzyme in the blood coagulation cascade. It is characterized by extensive genetic polymorphism defined by 4 common alleles, F13A*1A, 1B, 2A and 2B and a few rare variants, some responsible for severe coagulation deficiencies. In order to infer the evolutionary affinities between the common F13A alleles we have applied PCR techniques to study, in a Northern Portuguese sample, a short tandem repeat polymorphism located within the 5' untranslated region of the F13A gene. The analysis of the molecular heterogeneity within the F13A gene products revealed that the four biochemical variants shared very similar, truncated, distributions of STR alleles and showed no signs of predominant haplotypic associations. These findings seem to support both the inferences that intragenic recombination played an important role in the generation of molecular diversity within each of the four main F13A alleles and that all the four F13A alleles must be rather old. Molecular heterogeneity levels allowed the identification of 1B as the oldest F13A allelic state, and 2A as the most recently generated allele, but were not different enough to accurately track the divergence of alleles 1A and 2B. However, additional analysis of linkage disequilibrium patterns indicates that 1B-->2B-->1A-->2A is the most likely evolutionary order of appearance of F13A main protein alleles, confirming and extending a previous hypothetical model inferred from their molecular features.
From July to December 1998, a hospital- and health center-based surveillance system for dengue was established at selected sites in Nicaragua to better define the epidemiology of this disease. Demographic and clinical information as well as clinical laboratory results were obtained, and virus isolation, reverse transcriptase-polymerase chain reaction, and serologic assays were performed. World Health Organization criteria were used to classify disease severity; however, a number of patients presented with signs of shock in the absence of thrombocytopenia or hemoconcentration. Therefore, a new category was designated as "dengue with signs associated with shock" (DSAS). Of 1,027 patients enrolled in the study, 614 (60%) were laboratory-confirmed as positive cases; of these, 268 (44%) were classified as dengue fever (DF); 267 (43%) as DF with hemorrhagic manifestations (DFHem); 40 (7%) as dengue hemorrhagic fever (DHF); 20 (3%) as dengue shock syndrome (DSS); and 17 (3%) as DSAS. Interestingly, secondary infection was not significantly correlated with DHF/DSS, in contrast to previous studies in Southeast Asia. DEN-3 was responsible for the majority of cases, with a minority due to DEN-2; both serotypes contributed to severe disease. As evidenced by the analysis of this epidemic, the epidemiology of dengue can differ according to geographic region and viral serotype.
A case of intracranial hemangioma in a neonate is described by the authors. The rarity of the condition raised differential diagnosis problems.
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