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Biomedical subjects

J Palacios

Publications and source records attributed to J Palacios.

At least 73 records · Page 4Linked to original sources
PubMed1992

Anencephaly and limb deficiencies.

Limb deficiencies (LDs) are rarely reported in anencephalic infants. A review of 662 patients in the literature on non-neural defects in anencephaly only showed five patients with LDs. We report on eight patients with various LDs from the records of 141 necropsies of the anencephalic infants found among 495,830 births. Compared with another group of anencephalic infants reported in the literature, the patients in this group of anencephalic infants with LDs were predominantly male, their mean gestational age was younger by approximately 5 weeks, their mean birth-weight was approximately 1,400 g less, and they presented with a higher incidence of polyhydramnios during gestational development. The association of this pair of anomalies, which was 100 times more frequent than expected, seems not due to chance. Since all eight patients had other multiple congenital anomalies (MCA), in addition to anencephaly and LDs, the postmortem study should be mandatory in anencephalic infants with LDs. The most common associated anomalies were cardiovascular and renal defects. Oral clefts, diaphragmatic hernia, esophageal atresia, and imperforate anus were also observed in these infants. The recognition of LDs in anencephalic infants indicates severe and extensive disturbance of the early embryogenesis (blastogenesis), which affects the midline of the embryo.

Anencephaly↗
PubMed1992

Craniorachischisis totalis and sirenomelia.

We report on a male infant with craniorachischisis totalis and sirenomelia, an association that seems to have been observed only 5 times before. In addition to these anomalies, the patient had hypoplasia of the phalanges of the right thumb. The pattern of associated malformations in infants with anencephaly and sirenomelia is reviewed. This condition, which combines cephalic and caudal defects of the embryo, could be considered an example of the "axial mesodermal dysplasia spectrum" and may be related to the midline developmental field concept.

Adult↗
PubMed1992

Human growth plate development in the fetal and neonatal period.

The development of the normal human upper tibial growth plate was studied at autopsy in 46 stillborns and 79 newborns of 20-41 weeks gestational age. During this time period, the histology of this plate evolves from a highly cellular structure with relatively poor columnar organization and matrix development to the well known structure seen later in postnatal life. The thickness of the growth plate, assessed in the area surrounding the longitudinal tibial axis, decreases continuously from 1.15 mm on the 20th week to 0.6 mm on the 38th week. This decrease results from losses of both matrix and cellular components, mostly of the latter. However, the relative fraction of area occupied by the matrix significantly increased (12%) and matrix area per cell increased 1.5 times over the last half of gestation, indicating a maturation process of the plate towards a more matrix-oriented structure with age. In this maturation process the number of cells per unit area does not change and the average size of the cells appears to decrease. Plate thickness does not decrease further in the final 3 weeks of pregnancy and increases in early neonatal life; this has no apparent influence on the tibial growth rate. In the period under study the relative anatomical participation of the upper tibial growth plate decreases from approximately 4% of the radiographic length of the tibia on the 20th week to less than 1% at term. Present data will provide fetal and neonatal growth plate standards needed to obtain a better understanding of this structure during both normal and abnormal conditions.

Bone Matrix↗
PubMed1992

Morphological changes in long bone development in fetal akinesia deformation sequence: an experimental study in curarized rat fetuses.

In order to investigate the transverse growth of the long bones during intrauterine development in the fetal akinesia deformation sequence (FADS), we studied curarized rat fetuses. Curarization was performed by daily subcutaneous administration of D-Tubocurarine from day 17 of gestation until term. Experimental fetuses were compared with a sham-operated control group. The total area and perimeter, the absolute and relative amount of periosteum and bone trabeculae, the major and minor axes, and the elongation factor were measured from histological cross-sections of the femoral metaphysis and diaphysis using an IBAS 1 image analysis system. Curarized rat fetuses showed growth retardation, a short umbilical cord, and multiple articular contractures, a phenotype consistent with FADS. Alterations in femoral shape and transverse growth that affected the diaphysis were noted in these fetuses. These included a decrease of total cross-section area and reduction of the absolute and relative amounts of bone trabeculae with marked thinning of the periosteum. Femoral cross-sections was rounder than controls. These results evidenced an impairment of the membraneous (periosteal) ossification of long bones produced by immobilization and/or decrease of muscular strength, and support our previous clinical findings of bone hypoplasia and osteopenia in FADS.

Animals↗
PubMed1992

Long bone development in extrinsic fetal akinesia: an experimental study in rat fetuses subjected to oligohydramnios.

The transverse growth of long bones during intrauterine development was studied in rat fetuses subjected to experimental oligohydramnios in order to determine whether the skeletal changes, if any, in extrinsic fetal akinesia were similar to those observed in curarized rat fetuses with the fetal akinesia deformation sequence. Oligohydramnios was induced by daily extraction of amniotic fluid from day 17 of gestation until term. Experimental fetuses were compared with a sham-operated control group. The total area and perimeter, the absolute and relative amount of periosteum and bone trabeculae, the major and minor axes, and the elongation factor were measured in histological cross sections of the femoral metaphysis and diaphysis with an IBAS 1 image analysis system. Rat fetuses in the experimental group showed multiple articular contractures, redundant skin, and lung hypoplasia, a phenotype consistent with the oligohydramnios sequence. No alterations in femoral shape and transverse growth of the metaphysis and diaphysis were noted in these fetuses. These results suggest that the main mechanical factor related to fetal bone modeling is muscular strength, while motion would be mainly involved in fetal joint development.

Animals↗
PubMed1992

Intra-uterine long bone growth in small-for-gestational-age infants.

To better understand the intra-uterine bone modelling and remodelling process in small-for-gestational-age (SGA) newborn infants, long bone growth was studied using postmortem X-ray films in a group of such infants (n = 34). Bone length, diaphyseal diameter, medullary diameter, cortical thickness, cortical area, the Barnett-Nordin index, and the percentage of cortical area were determined in femur, tibia, and humerus. A separate group of appropriate-for-gestational-age (AGA) newborn infants (n = 146) was used as controls. Length and cortical bone mass in all three bones were significantly lower in SGA infants than in AGA infants. Decreased cortical bone mass in SGA infants was the result of decreased diaphyseal diameters and increased medullary diameters. Similar results were obtained when SGA infants were subclassified as preterm and term and compared with the control group of AGA infants. Bone lengths and diaphyseal diameters in SGA infants did not differ from those observed in a weight-matched control group of AGA infants although the latter were younger by 4 weeks' gestation. However, the cortical bone mass was lower than in the control group because of the relative greater medullary diameters in all three long bones in the SGA infants. Our present results indicate that reduced cortical bone mass in SGA infants is a mixed growth modelling and remodelling dependent process.

Bone Density↗
PubMed1992

Development of hepatic microsomal activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and cholesterol 7 alpha-hydroxylase in the young chick.

1. The 3-hydroxy-3-methylglutaryl-CoA reductase activity increased from 1 to 4 weeks of age, but decreased from 4 to 8 weeks of age. 2. Cholesterol 7 alpha-hydroxylase activity increased from 1 to 4 weeks, decreased from 4 to 6 weeks, and increased again from 6 to 8 weeks of age. 3. Serum total and free cholesterol concentrations decreased from 1 to 6 weeks of age, but increased from 6 to 8 weeks of age.

Animals↗
PubMed1992

The role of the condylar cartilage in mandibular growth. A study in thanatophoric dysplasia.

A new approach to evaluate the role of the condyle in mandibular growth could be its study in chondrodysplasias. The growth of the condylar cartilage and the mandible has not previously been reported in thanatophoric dysplasia (TD), a lethal osteochondrodysplasia. We have studied the light microscopic, histomorphometric, and radiologic findings in four infants affected by TD and in four control infants. The diagnosis was made on the basis of clinical, radiographic, and pathologic criteria. All the measured radiographic parameters of the patients' mandibles showed a normal longitudinal growth in TD, despite the severe disturbance of the condylar cartilages. The lesions in the chondroblastic cells and the extracellular matrix were similar to those observed in growth plate cartilages in TD. Marked membranous ossification spread from the cartilage canals of the condyles. The articular and prechondroblastic layers were histologically normal. Histomorphometry demonstrated that condylar cartilages were twice as thick as normal in TD, mainly because of the thickening by the chondroblastic layer. Present results support the hypothesis that condylar cartilage is a secondary growth site instead of being a primary growth center.

Cartilage↗
PubMed1992

Transverse bone growth and cortical bone mass in the human prenatal period.

The prenatal development of the normal diaphysis of the human long bone was studied through postmortem radiographs in 60 stillborns and 86 newborns of 20-41 weeks gestational age. Quantitative parameters were determined for the tibia, femur, and humerus. In all three long bones, significant positive correlations were found between the diaphyseal diameter, medullary diameter, cortical thickness, and cortical area, and the gestational age, body weight, body height, and bone length. No significant differences in any studied parameters were observed between males and females. In the tibia, the diaphyseal diameter grew more than in the femur and humerus. In these two latter bones, the medullary diameter growth rate was greater than the diaphyseal diameter growth rate, and thus the Barnett-Nordin index and percentage of cortical area showed mild but significant negative correlations with gestational age, body weight, body height, and bone length. The velocity of medullary diameter growth was similar (0.05 mm/week) in all three long bones; however, the velocity of diaphyseal diameter growth was greater in the tibia (0.161 mm/week) than in the femur (0.142 mm/week) or humerus (0.129 mm/week). The diaphyseal growth rate decreased in the second half of the period studied in all three bones. This decrease was more striking in the humerus. Observed differences in diaphyseal growth among the long bones studied may be genetically determined in relation to its different postnatal functions.

Bone Development↗
PubMed1992

Mechanisms underlying trypanosome-elicited immunosuppression.

T-cell proliferative responses of lymph node cells are profoundly suppressed during experimental infections of mice with Trypanosoma brucei. The active suppression of lymph node T-cell proliferative responses is attributed to the coexistence of at least two unlinked suppressive mechanisms that block different T-cell regulatory steps and operate through different effector mechanisms. The generation of prostaglandin-producing macrophages is entirely responsible for the suppression of IL-2 production whereas the induction of a prostaglandin-independent suppressive mechanism accounts for the suppression of the expression of IL-2 receptors (IL-2R). Both mechanisms are mediated by the cells that co-purify which macrophages. Despite an impairment at the level of T-cell proliferation, lymph node cells from T. brucei infected animals produce substantial amounts of interferon-gamma (IFN-gamma) and this lymphokine participates in the down-regulation of IL-2R expression. T-brucei-pulsed macrophage cell lines acquire concomitantly the potential to suppress T-cell proliferative responses and to stimulate CD8+ T-cells to secrete IFN-gamma. The sensibilization of CD8+ T cells by T. brucei-pulsed macrophages might be mediated by TNF-alpha. Collectively, these results indicate that the uptake of T. brucei by macrophages, either in vivo or in vitro, results in the generation of suppressive cells that annihilate T-cell proliferative responses. Furthermore, at least two cytokines (i.e., TNF-alpha and IFN-gamma) are released during these interactions. Besides playing a role in the pathway of T-cell immunosuppression, TNF-alpha and IFN-gamma could also contribute to immunopathological features that occur during trypanosome infections.

Animals↗
PubMed1991

Pathogenetic mechanisms of fetal akinesia deformation sequence and oligohydramnios sequence.

This article briefly reviews the participation of fetal compression, muscular weakness, and fetal akinesia in the genesis of the anomalies found in fetal akinesia deformation sequence (FADS) and oligohydramnios sequence (OS). Both sequences share phenotypic manifestations, such as arthrogryposis, short umbilical cord, and lung hypoplasia, in relation to decreased intrauterine fetal motility. Other characteristic manifestations found in OS, such as Potter face, and redundant skin, are produced by fetal compression. On the other hand, growth retardation, craniofacial anomalies, micrognathia, long bone hypoplasia, and polyhydramnios found in FADS could be related to intrauterine muscular weakness.

Abnormalities, Multiple↗
PubMed1991

Alagille syndrome associated with caudal dysplasia sequence.

A 36 day-old male with typical features of Alagille syndrome presented at birth additional features consistent with the diagnosis of caudal dysplasia sequence: imperforate anus, rectourethral fistula, lumbosacral abnormalities, and dysplastic right kidney. The association of these 2 conditions has not been previously reported, and could indicate the existence of an axial mesodermal dysplasia, of variable extension, in the Alagille syndrome.

Abnormalities, Multiple↗
PubMed1991

Sirenomelia and anencephaly.

We report on a monozygotic twin with sirenomelia and anencephaly. This association seems to have been observed only twice before. In addition to these anomalies the patient had cleft palate, rachischisis, and segmentation vertebral anomalies affecting the cervical and the upper thoracic spine. The second twin was a liveborn female infant with a large cystic paraovarian teratoma, and duplication of internal genitalia.

Anencephaly↗
PubMed1991

Polyasplenia, caudal deficiency, and agenesis of the corpus callosum.

Fullana et al. [Am J Med Genet (suppl. 2): 23-29, 1986] reported on 2 sibs with an autosomal recessive syndrome of caudal deficiency and polyasplenia anomalies. We report on a similar patient in which agenesis of the corpus callosum (ACC) was also found. Such an association has not been reported previously. This finding of ACC is to be interpreted as another midline anomaly rather than as a causally independent malformation.

Agenesis of Corpus Callosum↗
PubMed1991

Apical mitochondria-rich cells in the human epididymis: an ultrastructural, enzymohistochemical, and immunohistochemical study.

An ultrastructural, enzymohistochemical, and immunohistochemical study of the ductus epididymis in normal men was undertaken to investigate the characteristics of the apical mitochondria-rich cells (AMRCs). These cells, which differ morphologically from the principal cells (PCs), appear in isolation in the caput epididymidis (5.8 +/- 1.7 cells per cross-sectional duct) and only occasionally in the corpus epididymidis. The morphologic appearance of AMRCs varies from slender cells extending from the basement membrane to the lumen to apical cells without apparent contact with the basement membrane. The former display a round pale nucleus located in the middle of the epithelium; the apical cells have a dark nucleus, which, surrounded by a narrow cytoplasmic band, protrudes into the lumen. The cytoplasm of AMRCs is electron-dense and contains numerous mitochondria surrounded by rough endoplasmic reticulum cisternae. In the apical portion, there are lysosomes, vesicles with an electron-dense granule, and vacuoles showing a variable size and content. The stereocilia are shorter and less numerous than those of the PCs. The AMRCs are similar to the PCs in the intensely positive reaction for the enzymatic activity acid phosphatase, as well as in the lack of reaction for alkaline phosphatase and phosphorylase activities. AMRCs differ from PCs in: (1) a more intense reaction to the enzymatic activities ATPase, NADP, and succinic dehydrogenease, (2) a more intense immunostaining by AE1/AE3 and Ks4.62 anti-cytokeratin antibodies, and anti-estradiol receptor protein (D5) antibodies, and (3) a lower staining affinity for epithelial membrane antigen (EMA) antibodies. No positive immunostaining for the anti-cytokeratin Ks8.6 antibodies was observed in either AMRCs or PCs.

Adenosine Triphosphatases↗