Biomedical subjects

M Pichardo

Publications and source records attributed to M Pichardo.

5 recordsLinked to original sources

PubMed2001

Valsequillo biostratigraphy. IV: Proboscidean ecospecies in Paleoindian sites.

Five proboscidean species have been found in Paleoindian sites from North to South America: two open-country adaptations, Mammuthus columbi and Cuvieronius tarijensis, two woodland and riparian forms, Mammut americanum and Mammuthus jeffersonii, and one tropical savanna species, Haplomastodon chimborazi. Their value in biostratigraphy and as ecological index fossils is discussed with particular emphasis on the Central Mexican Paleoindian sites.

Animals↗

PubMed2000

Valsequillo biostratigraphy. III: Equid ecospecies in Paleoindian sites.

Greater precision in North American Pleistocene equid taxonomy makes it now possible to exploit the ubiquitous horse remains in Paleoindian sites as ecological index-fossils. The horses of Central Mexico and the Southern Plains can be sorted by tooth size alone, except for two rare large horses of the Southern Plains. The species endemic to these grasslands and south to Central Mexico are Equus pacificus (large), E. conversidens (small), E. francisci (smallest). The Southern Plains were also occupied by a specialized grazer E. excelsus (Burnet and Sandia caves) and E. occidentalis (Dry and Sandia caves). West of the Rocky Mountains E. occidentalis was dominant. East of the Mississippi River two woodland species are found: E. fraternus and E. littoralis.

Animals↗

PubMed1998

Amerind taxonomy and testable hypotheses.

The acceptance of a 30,000 yr B.P. age for Valsequillo sets new parameters for hypotheses of Paleoindian entry into America. A review of Amerind taxonomy defines the early groups as Otamid-Sundadonts. Isolation in America led to an adaptive radiation that has implications for the origin and dispersal of Pithecanthropus.

Acculturation↗

PubMed1991

Cognitive abilities in androgen-insensitive subjects: comparison with control males and females from the same kindred.

To determine the effect of androgen insensitivity on cognitive abilities, subjects with the syndrome of complete androgen insensitivity (AI) were compared to control males and females from the same kindred on the Spanish version of the Wechsler Adult Intelligence Scale (WAIS). All subjects had similar sociocultural backgrounds and only right-handed subjects were used in the primary analysis. This design was chosen to diminish the effect of critical variables on test performance, thereby highlighting the effect of androgen unresponsiveness on cognition. The results indicated that control males and females were superior to androgen insensitive subjects on the Perceptual Organization factor, which included five visuospatial subtests. Separate analysis of these subtests revealed that males performed significantly better than females on Block Design, Picture Completion, and Object Assembly, and better than androgen insensitive subjects on all five subtests. Females were superior to androgen insensitive subjects on four subtests (Block Design, Picture Completion, Digit Symbol, and Picture Arrangement). Despite the small sample size, when female siblings were compared to their AI sisters, they were also superior on these four visuospatial subtests. The difference between the Verbal Comprehension and Perceptual Organization factors was greatest in androgen-insensitive subjects, while control males demonstrated the least difference. Females and AI subjects did not differ from one another on the Freedom from Distractibility factor nor on the subtests comprising it, but their performances were poorer than control males. None of the groups differed significantly on Full Scale IQ, Verbal IQ, the Verbal Comprehension factor, or any subtests included in this category.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1986

The diagnosis of 5 alpha-reductase deficiency in infancy.

The diagnosis of 5 alpha-reductase deficiency in infancy is reported for the first time in three male pseudohermaphrodites from the Dominican Republic. Basal plasma testosterone to dihydrotestosterone ratios were significantly elevated in two of the three affected infants, and increased markedly in all three infants after administration of hCG. Since urinary etiocholanolone to androsterone ratios could not be determined accurately in this age group, the diagnosis of 5 alpha-reductase deficiency was confirmed by the finding of elevated urinary tetrahydrocortisol (THF) to 5 alpha-tetrahydrocortisol (5 alpha-THF) ratios, as determined by gas chromatography/mass spectrometry, in the affected male infants compared to those in age-matched normal infants. The THF/5 alpha-THF ratios, however, were lower in both the normal children and the affected infants, suggesting increased 5 alpha-reductase activity in infancy. The affected infants had THF/5 alpha-THF ratios comparable to ratios in adult carrier males and significantly lower than ratios in adult homozygotes. Two of the three affected infants are related to the large Dominican kindred we studied previously and initially were raised as females but, after parental counseling, were changed to a male sex of rearing.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗