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Biomedical subjects

L Palacios

Publications and source records attributed to L Palacios.

At least 55 records · Page 3Linked to original sources
PubMed1983

In vitro and in situ formation of neuron-glia junctions.

The formation of neuron-glia junctions during neurogenesis has been considered as an error of the neuronal specificity mechanism or as a consequence of the artificial conditions when observed in central nervous system tissue culture. We report the demonstration of the regular existence of synaptic-like junctions in tissue cultures prepared from different regions of chick central nervous system as well as the occurrence of such intercellular contacts in the cerebellum of adult and normal frogs. The formation of neuron-glia junctions in tissue culture during normal neurogenesis and their presence in adult frogs seem to indicate that those types of neuron-glia relationships are not a simple biologic error. Rather, we propose that they may represent a primitive, but normal neuron-glia interaction.

Animals↗
PubMed1982

In vitro development of chick hypothalamic neurosecretory cells.

The in vitro maturation of chick hypothalamic neurosecretory cells has been studied by the Golgi method and electron microscopy. Rotary cultures prepared from chick embryos aged 6, 8 and 10 days of development fail to assemble histotypic cultures; however, cultures prepared from older embryos, i.e. 12, 14 and 16 days of development, progressively exhibited more neurosecretory characteristics. It is interesting to point out that cultures prepared from 12-, 14- and 16-day-old chick embryos form complex surfaces composed of patches of glioepithelial cells alternating with zones containing neurosecretory nerve endings partially surrounded by glial processes. This particular distribution of the nerve endings seems to indicate that cytotypic hypothalamic neurons in rotary cultures deliver their products to the incubation medium; this interpretation is further reinforced by the observed exocytosis of the neurosecretory material within the external neuropile of histotypic cultures. Details of the neurosecretory cell maturation are given in the text.

Animals↗
PubMed1981

Synaptogenetic mechanisms during chick cerebellar cortex development.

Chick embryo cerebellar cortex development was analyzed in an attempt to visualize the fine ultrastructural changed involved in cortical synaptogenesis. Three major stages of synapses formation were detected during days 13 to 18 of maturation: intermembranous adherence, cytoplasmic recognition, and definitive synaptic formation period. The more primitive morphological event indicative of synaptic onset was the occurrence of external plaques; these plaques must have a negative charge since they accumulated cationized electron-dense tracers. These plaques favor the adhesions between parallel fibers and Purkinje cell dendrites. Once axonal and dendritic membranes adhered to form an adhesion contact, the dendritic half of this contact forms a pinocytic vesicle that incorporates part of the membrane of the axonic half of the contact. This particular pinosome delivers its content to different cytoplasmic organelles including the nucleus. At day 15 Purkinje cells significantly increase the number of dendritic-forming pinocytic vesicles; this phenomenon means that during this day a large amount of parallel fiber membrane is passed into the Purkinje cell cytoplasm. From day 15 to 16 postsynaptic densities begin to appear; ribosomes associated to these structures seem to be the origin of a progressively accumulated amorphous material composing the rare primitive postsynaptic densities. Some other morphological details related to these processes are given in the text.

Animals↗
PubMed1979

In vitro formation of neuroglial synapses.

Neuroglial synapses have been systematically observed in histotypical cerebellar rotary tissue cultures. These axoglial contacts appear as excitatory-like synapses in which the presynaptic element contains rounded synaptic vesicles accumulated at the presynaptic active zone. The post-synaptic structures were always the somata as well as processes of astrocytic glial cells. The axoglial contacts appear in these cultures when they are prepared from 16-day-old chick embryos cerebellum and cultivated during 6 days. To explain these neuroglial interrelationship it has been suggested as a working hypothesis that glial and nerve cells develop plastic capacities in order to establish synaptic contact in the in vitro conditions.

Animals↗
PubMed1976

In vitro vs in situ development of Purkinje cells.

Analysis of in vitro vs in situ development of Purkinje cells was undertaken in order to compare the transitory morphology of Purkinje cells grown in situ with their differentiation in vitro. Purkinje cells in rotary cultures developed their basic morphological pattern only when the cultures were prepared from 16-day chick embryos, indicating the existence of a critical period during their normal differentiation, which lasted approximately 24 hr between days 14 and 15 embryonic development.

Animals↗
PubMed1976

Ferritin intestinal absorption.

Ferritin as a source of iron was consiered. A good iron absorption rate appears in normal rats with an in vivo absorption technique. The same absorption appears in iron-deficient animals. The iron stored in intestinal wall is lower in anemic rats than in normal ones, suggesting a higher draw of iron from lumen to blood.

Anemia, Hypochromic↗
PubMed1975

A comparison of some methods for determining oxygen dissociation curves of fish blood.

A brief description is given of four different methods for determining the oxygen dissociation curve of trout blood at pH 7.8 and 15 degrees C. A comparison of the results obtained indicates that the methods give similar results, especially when used by experienced workers. The relative advantages and disadvantages of the methods for determination of some O2-carrying parameters of fish blood are discussed.

Animals↗
PubMedDate not supplied

[Latex allergy].

OBJECTIVE: To review the etiology, diagnosis, prevention and treatment of latex allergy in the hospital setting, and to establish a list of potentially hazardous drugs. METHOD: A literature search was performed. A guide about latex-containing drugs (any component) was developed by contacting manufacturers. RESULTS: The most relevant factor for latex sensitization is exposure extent. Regarding diagnosis the medical history and skin testing are crucial; regarding secondary prevention, identifying the various at-risk groups. Immunotherapy is currently considered a valid option for the management of this condition. CONCLUSIONS: The development of a guide listing latex-containing drugs is essential for the primary prevention of allergic reactions to this substance in hospital.

Algorithms↗