Search PubMed⌕ Search

Biomedical subjects

F R Santos

Publications and source records attributed to F R Santos.

27 records · Page 2Linked to original sources
PubMed1995

PCR haplotypes for the human Y chromosome based on alphoid satellite DNA variants and heteroduplex analysis.

We have developed a system for revealing informative and useful haplotypes for the human Y chromosome using PCR. Variant alphoid satellite DNA subunits were amplified and analysed by digestion with HindIII to score a restriction site polymorphism, or on polyacrylamide gels to reveal 13 heteroduplex haplotypes. Heteroduplexes are double-stranded DNA molecules containing mismatches; the haplotype is the combination of alleles on the same chromosome. Structural studies showed that the heteroduplexes analysed here were formed from loci at the left (short arm) and right (long arm) edges of the centromeric alphoid array which differed by a 4-bp insertion/deletion and several point mutations. Consequently, many haplotypes may have arisen only once and are useful for evolutionary studies.

Base Sequence↗
PubMed1993

Testing deficiency paternity cases with a Y-linked tetranucleotide repeat polymorphism.

Because a son's genotype at a Y-linked locus uniquely specifies his father's genotype at that locus irrespective of the maternal contribution, Y-linked polymorphisms show increased exclusion power over autosomal polymorphisms in paternity cases involving a male child. This advantage is even more obvious when the alleged father is deceased or otherwise unavailable for testing. In this situation, any individual connected by patrilineage to the alleged father may be tested in his place. The usefulness of the Y-linked tetranucleotide repeat locus Y-27H39 in deficiency cases was evaluated in a set of 41 families that had a deceased alleged father and that had been tested at GENE/MG with multilocal and unilocal DNA fingerprinting probes. In sixteen of these cases the proband (child tested) was male and there were male relatives. In the thirteen cases in which paternity was included, Y-27H39 would contribute significantly to the paternity index. In one of three cases in which there was exclusion by fingerprinting probes there was also exclusion by Y-27H39. Thus, Y-27H39 is useful in deficiency paternity cases and will be specially valuable in situations where autosomal polymorphisms have limited power, such as when there is only one male living relative of the deceased father. However, our experience is that Y-linked probes can only be applied in approximately 40% of cases.

Base Sequence↗
PubMed1993

Genetic and population study of a Y-linked tetranucleotide repeat DNA polymorphism with a simple non-isotopic technique.

A polymorphic microsatellite (Y-27H39) based on a (GATA)n repeat was recently discovered on the short arm of the human Y chromosome. We have used a simple technique based on polymerase chain reaction amplification and native polyacrylamide gel electrophoresis followed by highly sensitive silver staining to study the inheritance, the genetic stability and the allele frequency distribution of this polymorphism in the Brazilian population. We have analyzed 100 randomly chosen Caucasian Brazilian father-son pairs with established paternity. Five alleles, four base-pairs apart, were easily distinguishable. Their frequencies were: A (186 bp), 0.19; B (190 bp), 0.49; C (194 bp), 0.24; D (198 bp), 0.07; E (202 bp), 0.01. In all father-son pairs, there was complete allelic concordance. From these data, the probability of discrimination for forensic cases and the average probability of exclusion for paternity cases were both calculated to be 0.66.

DNA Fingerprinting↗
PubMed1993

[Profile of the elderly in a metropolitan area of southeastern Brazil: results of a domiciliary survey].

A multicentre study concerned with the health needs of the elderly population living in urban areas and coordinated by the Panamerican Health Organization was undertaken in 6 Latin-American countries. In Brazil, 1,602 elderly residents (of 60 years of age and over) in the District of S. Paulo, constituting a multistage random sample stratified by socioeconomic status, participated in a household survey using a multidemensional functional assessment questionnaire. The results showed a highly deprived population (70% had a per capita income of less than US $ 100 per month), living mostly in multigenerational households (59% were living with children and/or grandchildren), with a high prevalence of chronic physical illnesses (only 14% referred no illness) and psychiatric disorders (27% were considered psychiatric cases), a high proportion of them showing a loss of autonomy (47% needed help in performing at least one of the activities of daily living). The results are put into perspective concerning future needs in terms of specialized health services and social support for the growing population of elderly people in Brazil.

Age Factors↗
PubMed1985

The 3, 4-didehydroretinal chromophore of goldfish porphyropsin.

The isomeric configuration of the 3,4-didehydroretinal chromophore of goldfish porphyropsin was determined by high performance liquid chromatography (HPLC) and by the regeneration of this visual pigment with authentic isomers of 3,4-didehydroretinal. A nonisomerizing, quantitative method using hydroxylamine and methylene chloride was employed to extract the 3,4-didehyroretinal chromophore from the rod outer segment membrane (containing the porphyropsin). When this extracted chromophore was injected into the HPLC, only a single major peak was observed and this peak coeluted with the authentic 11-cis 3,4-didehydroretinyl oxime. This suggests that the chromophore of goldfish porphyropsin is 11-cis 3,4-didehydroretinal. When the bleached rod outer segments (containing the opsin) were incubated with different 3,4-didehydroretinal isomers (13-cis, 11-cis, 9-cis, and all-trans), only the 11-cis isomer resulted in the degeneration of porphyropsin. This also suggests that the porphyropsin chromophore exists in the 11-cis configuration.

Animals↗