PubMed Health⌕ Search

Biomedical subjects

A Fonseca

Publications and source records attributed to A Fonseca.

At least 37 records · Page 2Linked to original sources
PubMed2000

Biodiversity and systematics of basidiomycetous yeasts as determined by large-subunit rDNA D1/D2 domain sequence analysis.

The molecular systematics of 337 strains of basidiomycetous yeasts and yeast-like fungi, representing 230 species in 18 anamorphic and 24 teleomorphic genera, was determined by sequence analysis of the D1/D2 region of the large-subunit rDNA. The data were compared with published sequences of other basidiomycetous fungi. The results demonstrated that the yeast species and genera are phylogenetically distributed among the Microbotryum, Sporidiobolus, Agaricostilbum and Erythrobasidium clades of the Urediniomycetes; the Tremellales, Trichosporonales ord. nov., Filobasidiales and Cystofilobasidiales clades of the Hymenomycetes; and the Ustilaginales, Microstromatales and Malasseziales clades of the Ustilaginomycetes. Genera such as Bensingtonia, Cryptococcus, Rhodotorula and Sporobolomyces are polyphyletic, i.e. they occur in two or more clades. In contrast, other genera, e.g. Bullera, Cystofilobasidium, Fellomyces, Filobasidiella, Filobasidium, Kondoa, Kurtzmanomyces, Leucosporidium, Rhodosporidium, Sporidiobolus and Udeniomyces, are monophyletic. The majority of the species can be identified using D1/D2 analyses, although the internal transcribed spacer region is required to distinguish closely related species. The intergenic spacer region is recommended for additional differentiation of species and strains.

Basidiomycota↗
PubMed2000

Diversity in the yeast Cryptococcus albidus and related species as revealed by ribosomal DNA sequence analysis.

Evidence accumulated from studies based on physiological, biochemical, and molecular characteristics has pointed to the heterogeneity of the ubiquitous anamorphic basidiomycetous yeast species Cryptococcus albidus (Saito) Skinner, with its current varieties and synonyms. The taxonomic status of this species has not been reappraised because different studies, mostly involving limited numbers of strains, have not been integrated. To assess species diversity within the clade containing Cryptococcus albidus and other phylogenetically related Cryptococcus and Filobasidium species, we determined ribosomal DNA (rDNA) sequences of 69 strains from the 5' end of the 26S gene, D1/D2 region, and in some cases, the non-coding ITS2 region. Analysis of the sequence data together with available physiological, biochemical, and molecular characteristics, showed the segregation of C. albidus into at least 12 species, leading to the elevation of former varieties to the rank of species (C. aerius, C. diffluens), the reinstatement of synonyms (C. liquefaciens, C. terricola), and the proposal of new species (C. arrabidensis, C. chernovii, C. cylindricus, C. oeirensis, C. phenolicus, C. saitoi, C. uzbekistanensis, C. wieringae). The overall analyses of the results argue in favour of the use of rDNA sequence data to improve species delineation when integrated with other available physiological and molecular characteristics.

Basidiomycota↗
PubMed1999

Child survival in children born to HIV-2 infected women in Guinea-Bissau, West Africa.

We have retrospectively studied the effect of maternal HIV-2 infection and other risk factors on child survival at a family planning centre in Bissau, Guinea-Bissau. A total of 2109 women were included, and the seroprevalence of HIV-2 was 5.7%. Overall child mortality of all live births (n=5912) reported by the women (standardized for age of the mother) was slightly higher among children of HIV-2 seropositive mothers (16.3%) compared with children of HIV seronegative women (14.6%) (not significant). There was a significant association between low level of maternal education and increased child mortality, but no difference in the level of education was found between HIV-2 seropositive and seronegative women.

Adult↗
PubMed1999

Cytonuclear disequilibria in wild populations of rabbit (Oryctolagus cuniculus L.) suggest unequal allele turnover rates at the b locus (IGKC1).

DNA sequence comparisons suggest that evolutionary rates at the rabbit IGKC1 locus can differ among allelic lineages. Here we address the question of whether population turnover rates can vary among IGKC1 alleles. We studied the distribution of sixteen IGKC1 (or b-locus) allotypes in areas comprising the aboriginal species range (Iberian peninsula). Rabbits in this area belong to one of two distantly related mitochondrial lineages (mtDNA types) A and B. In the more recent distribution area of the species, all rabbits belong to the mtDNA type B lineage, and IGKC1 alleles b4 and b5 comprise over 90% of the gene pool. These two alleles are also predominant in areas of mtDNA type B prevalence within the Iberian range. However, in areas of mtDNA type A prevalence, the b4 and b5 allotypes are rare or absent; they apparently have been replaced by serologically related, but distinct, 'endemic' variants. The cytonuclear disequilibria were highly significant, also within the subsample consisting of populations from Spain. These observations suggest that allelic persistence times for the predominant IGKC1 lineages could be shorter than the divergence time of the major mtDNA lineages A and B. In contrast, the relative gene frequencies of the IGKC1 allele b9 were similar among the type A and type B rabbits; it was present in most populations at low frequency. In consequence, persistence times of the b9 allele appear to be longer than the divergence time of lineages A and B. The data reported here are in agreement with the DNA sequence data, providing further proof that the molecular clock can run at different rates among allelic lineages at the rabbit IGKC1 locus.

Alleles↗
PubMed1996

Study of lens autofluorescence by fluorophotometry in pregnant patients with diabetes.

PURPOSE: Lens autofluorescence originates from an accumulation of fluorescent substances such as the tryptophan-derived residues and glycosylated protein aggregations, which are associated with the process of cataractogenesis and lens aging. The purpose of this investigation is to determine whether pregnancy alters the typical constituents of the lens autofluorescence in patients with diabetes and, if so, to what degree this may occur. METHODS: Lens autofluorescence was studied with fluorophotometry in 127 eyes of 72 individuals: 23 control subjects, 6 healthy pregnant women, 21 patients with diabetes, and 44 pregnant patients with diabetes. RESULTS: The autofluorescence values were 311 +/- 130 ng/ml, 253 +/- 40 ng/ml, 378 +/- 110 ng/ml, and 562 +/- 164 Eq ng/ml (Eq ng/ml = Ng/ml equivalent fluorescein) in the four groups, respectively. The difference between the nonpregnant and pregnant patients with diabetes was significant (P < 0.001). CONCLUSION: These results suggest that there is an important deterioration in the metabolic state of the lens during gestation in patients with diabetes, as is the case for diabetic retinopathy.

Adult↗
PubMed1995

Spin relaxation studies of pyrene by 13C nuclear magnetic resonance spectroscopy.

The effect of the repetition and contact times on the intensity of the magic-angle spinning (MAS) spectra of pyrene has been studied. Pyrene, like a great number of fused polyaromatic compounds, has a very large 13C longitudinal relaxation time (T1Z). When using the cross-polarization (CP) MAS technique, the optimum repetition time is 800 s. The simulation of the central line of the pyrene CP-MAS spectra allowed us to determine the chemical shift of each carbon in the solid state. As the T1Z (13C of the total spectrum) of pyrene was observed to be 1780 s, attempts have been made to relax it by the addition of chromium(III) acetylacetonate or by supporting it on a carrier of gamma-Al2O3: the mixing of chromium(III) acetylacetonate to pyrene by solid mixing, or solution mixing followed by evaporation of the solvent, has no effect on its relaxation time; the Haldor Topsøe TK551 catalyst, a gamma-alumina supported Ni-Mo-P catalyst, has been found to be a very efficient spin relaxation agent for the products adsorbed on it. For example, at 25 degrees C, the 10 wt.-% pyrene-TK551 catalyst is 3 x 10(4) times more relaxed than pure pyrene.

Adsorption↗
PubMed1995

[Lipids in children and young people. A public health problem].

Cardiovascular diseases represent an important Public Health problem among us. It is known that the atherosclerotic process on which they are based is mostly dependent on hyperlipidemia, mainly of those characterized by hypercholesterolemia and starts early in childhood. In this paper some lipid parameters were evaluated in children and youngsters and the prevalence of those at risk was compared with the one found in a population sample of adult people, collected at random, using the same determinations and laboratory methods. The authors conclude that preventive measures should be implemented as early as possible in childhood as there are many children and youngsters with hypercholesterolemia and the latter may become lower; some ideas and recommendations for those measures are pointed out.

Adolescent↗
PubMed1995

Quality assurance programmes in Portugal in the fields of clinical chemistry and haematology.

Quality assurance programmes in Portugal in the fields of clinical chemistry and haematology are running on under the organization of the correspondent laboratories of the National Institute of Health. They are carried out with voluntary participation for public and private clinical laboratories with confidentiality of results. The design comprehends two parts, each one supplementing the other: internal quality control, external quality assessment being the motivation for quality assurance usually done through courses and laboratory activities organized even before the laboratories enter the external scheme. In clinical chemistry: with six trials a year and 23 parameters to be analysed, the target values are assigned by reference laboratories. The survey reports involve a personal message and an Youden plot being the assessment of performance done either by a deviation index (DI) or, on enzymes, by a consensus value established among the participants. Yearly an individual message is produced to report the evolution of laboratory results. The state of the art shows a good performance of reference laboratories. The participant laboratories still evidence some difficulties on enzymes, bilirubin, creatinine, urates and urea determinations. In haematology the target value is the consensus median value of participant laboratories using the same kind of equipment, semi and totally automated. As survey reports two kinds of computer forms are produced: an individual message where each laboratory results are compared with the others through a DI, an yearly message with the DI evolution. Up to this date ten surveys a year are carried on for general haematology.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemistry, Clinical↗
PubMed1994

[The Program of External Quality Evaluation in Clinical Chemistry. An overview and evaluation after 11 years of functioning].

After an eleven-year period, the goals and way of functioning are remembered the External Quality Assessment Scheme in Clinical Chemistry, under the responsibility of the National Institute of Health. The authors try to evaluate the quality of results obtained at the time by the 160 participant laboratories, belonging to the public and private sectors as well as to the Portuguese reference laboratories which have to assign the expected values on the control sera to be analysed. As regards the 22 biochemical blood parameters, we came to the conclusion that there is a high performance level in what concerns the reference laboratories and a quality level of participant laboratories in accordance with their considered peer foreign laboratories.

Chemistry, Clinical↗
PubMed1992

Utilization of tartaric acid and related compounds by yeasts: taxonomic implications.

A survey of yeasts capable of growing on L(+)-tartaric acid as the sole source of carbon and energy showed that this organic acid is assimilated by a significant number of species of basidiomycetous affinity and is seldom utilized by ascomycetous yeasts. This conclusion was further supported by the fact that among approximately 100 isolates from various natural substrates, using selective media with L(+)-tartaric acid, only one strain of ascomycetous affinity was obtained. In a more comprehensive survey 442 yeast strains belonging to 138 species, mostly of basidiomycetous affinity, were also screened for the assimilation of different aldaric acids: D(-)-tartaric acid, meso-tartaric acid, L(-)-malic acid, D(+)-glucaric acid (saccharic acid), and galactaric acid (mucic acid). L(+)-Tartrate was the most frequently utilized tartaric acid isomer (55% of the total number of strains of basidiomycetous affinity belonging to either the Tremellales/Filobasidiales or the Ustilaginales) when compared with the D(-) and meso forms, which were assimilated by 12 and 18% of the total number of strains, respectively (mainly of tremellaceous species). Saccharic acid was utilized by about 75% of the total number of species of Tremellales affinity and by less than 20% of the ustilaginaceous species. Assimilation of mucic acid occurred in more than 50% of the tremellaceous species and only in 5% of the species related to the Ustilaginales. These tests, not used in standard yeast identification sets, appear to contribute to distinguishing taxa at or above the species level.

Basidiomycota↗
PubMed1991

Transport of lactic acid in Kluyveromyces marxianus: evidence for a monocarboxylate uniport.

Lactic acid-grown cells of a strain of Kluyveromyces marxianus transported D- and L-lactic acid by a saturable mechanism that was partially inducible and subject to glucose repression, with the following kinetic parameters at pH 5.4: Vmax = 1.00 (+/- 0.13) mmol h-1 per g dry weight and Ks = 0.42 (+/- 0.08) mM. Lactic acid transport was competitively inhibited by pyruvic, glycolic, acetic and bromoacetic acids. The latter, a non-metabolizable analogue, was transiently accumulated, the extent depending on the extracellular pH. The pH dependence of the Ks values for undissociated lactic acid and for the lactate anion indicated that the latter was the transported species. Lactate uptake was not accompanied by the simultaneous uptake of protons, potassium ions or sodium ions excluding symport mechanisms. Initial lactic acid uptake led to transient membrane hyperpolarization as measured with a fluorescent dye excluding also an electroneutral anion antiport mechanism. It was concluded that lactate anions use a monocarboxylate uniport and that the counter anion, possibly bicarbonate, uses a separate channel, the coupling being electrical and loose.

Acetates↗
PubMed1991

Bulleromyces genus novum (Tremellales), a teleomorph for Bullera alba, and the occurrence of mating in Bullera variabilis.

Mating is observed in Bullera alba and B. variabilis, resulting in the formation of dikaryotic mycelium with clamps, haustorial branches, and lateral and terminal dikaryotic, clavate, lageniform or subglobose cells. These cells develop in B. alba into tremellaceous phragmobasidia. Karyogamy has been observed in young non-divided basidia. Germination of the phragmobasidia occurred by acropetal chains of yeast cells, ballistospores or hyphae. Septal pores are dolipores with parenthesomes made up of U-shaped vesicles (Tremellales type). For the teleomorph of B. alba a new genus, Bulleromyces, is proposed, with only one species, viz. Bulleromyces albus.

Basidiomycota↗
PubMed1991

Cryptococcus yarrowii sp. nov., a novel yeast species from Portugal.

A novel species of the basidiomycetous genus Cryptococcus is described as Cr. yarrowii based on the study of an isolate from a decayed mushroom collected in Portugal. DNA-DNA homology with the type strain of the phenotypically similar species Cr. albidus was 10 +/- 2%.

Cryptococcus↗
PubMed1988

The somatosensory evoked potential predicts neurologic deficits and serotonergic pathochemistry after spinal distraction injury in experimental scoliosis.

The validity of the somatosensory evoked potential as an intraoperative spinal cord monitor was evaluated in an experimental model of scoliosis in the rat and a Harrington distraction model of injury. Under these conditions, it was found that any change in latency or amplitude of the major negative wave above a certain level was a significant predictor of an adverse neurologic outcome. Changes in latency of 4% or greater and changes in amplitude of 50% or greater were unequivocal indicators of spinal cord injury. Postmortem analyses of the spinal neurotransmitter serotonin revealed that apparent false-positive results of the SEP were, in fact, true-positive results.

Animals↗
PubMed1986

Iron and akathisia.

Explore the source record for details and available documents.

Akathisia, Drug-Induced↗