Biomedical subjects
Publications and source records attributed to F Rivas.
A theoretical model to explain the occurrence of some structural mosaicisms is proposed. It is based on a prezygotic (meiotic) half chromatid mutation leading, after the first post-zygotic DNA replication, to a structural mosaic.
A female infant with partial trisomy 3p and a terminal deletion 12p, due to a paternal (3;12)(p25.1;p13.31) translocation is described. Normal glyceraldehyde-3-phosphate (GAPD) activity in the proposita tentatively excludes GAPD locus from the deleted segment. Therefore, the region for this locus is reduced to 12p13.1----p13.31.
A 4 4/12 year-old girl with a peculiar phenotype due to a 46,XX/46,XX, dir dup(7)(p1300----p2200) karyotype is described. The comparison with about ten similar cases permitted a better delineation of the 7p trisomy syndrome and the assignment of the band 7p21 as the critical one. Mechanisms for the origin of homogeneous and mosaic duplications, including one model based on a meiotic half chromatid duplication, are discussed.
A newborn female with craniofacial clefts, including cleft lip and palate, was studied. The mother had ingested 580 mg of diazepam in a single dose at about the 43rd day of gestation. The synchronism of the drug intake and the embryological development of the affected structures suggests an etiopathogenic relationship.
A 12 month-old male patient with a karyotype 46,XY,-15,+der(15),t(13;15)(q22;q26)pat is presented. His stillborn sib showed malformations compatible with the 13q deletion syndrome, probably due to a 46,XY,der(13) karyotype. Phenotypic analysis of 41 cases from the literature with partial distal 13q (D13q) trisomies indicate that the segment 13q22----qter in trisomy with or without another concomitant aneusomy is sufficient to produce the majority of the trisomy 13 syndrome features, some of which (cleft palate, increased HbF and projections in PMN) are present in different non-overlapping partial 13q trisomies. About 82% of the D13q trisomies are inherited, more frequently from the mother.
Thirteen patients from three unrelated families were found to have microcephaly, without any neurological or dysmorphic manifestations. Autosomal dominant inheritance is concluded since the trait was transmitted directly in all three families, including one male-to-male instance. The recognition of this uncomplicated form of microcephaly as a Mendelian trait further extends its etiological heterogeneity.
A 37 year-old female patient with polyostotic fibrous dysplasia (PFD) is described. She presented the typical "café au lait" spots and severe bone involvement including a maxillary osteosarcoma. The father, four sibs, two nephews, two paternal aunts and two paternal first cousins were clinically examined, and seven of them also radiologically evaluated. "Café au lait" spots were found in the father, three sibs, one nephew, one aunt and one first cousin. Although no definite PFD bone lesions, mild radiological abnormalities were found in the father, three sibs and one nephew. These findings were interpreted as the variable expression of a pleiotropic gene. The present observation and three previous familial cases of this entity strongly suggest the existence of a form of PFD determined by an autosomal dominant gene.
A two-year-old girl with a "pure" 21pter leads to q21 monosomy secondary to a 3:1 segregation of a maternal translocation t(14;21)(p12;q22) is described. The father's karyotype was 46,XY,t(5;18)(q32;q22). This observation permits to further delineate the 21q proximal monosomy syndrome and to comment the very rare finding of a couple in which both partners have different reciprocal translocations.
Sorbitol dehydrogenase was electrophoretically determined in 173 different samples of human seminal plasma in cellulose acetate as support media. This method permitted the identification of three phenotypes : one with a slow band, one with a fast band and the third with both slow and fast bands. These findings can be explained either by the presence of two alleles at a different SORD locus determining the enzyme in seminal plasma or by the formation of secondary isozymes.
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A girl aged 13 years and 9 months with a phenotypic appearance of 9p trisomy was studied. Chromosome analysis of peripheral blood lymphocytes revealed a 9p tetrasomy [47,XX,+i(9p)] with no evidence of mosaicism. Biochemical studies corroborate the gene dosage effect for galactose-1-phosphate uridyltransferase. The roentgenological findings were quite similar to those of the 9p trisomy except for hypoplastic and angulated ribs, and malformed vertebral bodies, which are probably exclusive of the tetrasomic state.
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Three 46,XY phenotypically male, azoospermic brothers out of thirteen sibs from a consanguineous marriage were studied and found to have a unique pattern of testicular histology with arrest of spermatogenesis at the pachytene stage of primary spermatocytes. Endocrinological evaluation showed elevated plasma luteinizing(LH) and normal to elevated follicle-stimulating (FSH) hormones, positive gonadotropin pituitary response to luteinizing hormone-releasing hormone, depletion of LH and FSH levels by exogenous testosterone (T) administration, normal levels of T and dihydrotestosterone hormones, and elevation of T after stimulation with human chorionic gonadotropin hormone. Electrophoretic assay of lactic dehydrogenase isozymes did not reveal band C4 in semen or testicular tissue. These traits seem to constitute a hitherto undescribed form of infertility in which spermatogenesis arrest at the first spermatocyte level is the main feature. The parental consanguinity suggests autosomal recessive inheritance.
Neutral alpha, 1-4 glucosidase activity was assayed by a spectrophotometric method using p-nitro-phenyl-alpha-D-glucopyranoside as the substrate in the seminal plasma of normal, vasectomized, and oligospermic men. The latter groups showed lower values than the controls. These results suggest that the main source of the alpha, 1-4 glucosidase activity is between the vasectomy site and the tubule, and that the enzyme is related to sperm density or to a spermatogenesis factor.
The feasibility of estimating the mean pulmonary capillary pressure (PCP) by simultaneous noninvasive recording of the ECG, phonocardiogram, and mitral valve echocardiogram was tested in 36 patients with miscellaneous heart lesions. The recordings were made in close sequence with direct measurement of PCP by a catheter. The interval from the onset of the QRS complex to the echocardiographic point C of mitral valve closure (Q-C) and the time from the aortic valve closure sound to the E point of the mitral echocardiogram (A2-E) were measured. The difference between these two intervals exhibited a good linear correlation with the PCP. A better correlation was found between the ratio (Q-C)/(A2-E) and the PCP, which is potentially useful in the noninvasive determination of PCP in several forms of heart disease.
Thickness and cellularity of motor cortical layers adjacent to epileptogenic lesions produced by administration of alumina cream (AC) were measured in the brains of 18 cats that were at latent, convulsive, and remissive stages of an experimental model of epilepsy. Sham-operated animals were used as controls. Brains were fixed by perfusion and embedded in paraffin. Sections of motor cortex adjacent to the AC deposit were obtained at constant thickness to measure thickness and cellularity in each cortical layer. A statistically significant reduction in thickness and cellularity was detected in layers 2, 4, and 6, whereas reduction in these aspects was not significant in layers 3 and 5 in the initial stages of the model (latent and convulsive). It is suggested that AC may exert a cytotoxic effect on inhibitory neurons located at layers 2 and 4, to determine an imbalance of intracortical excitability.