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J Rueda

Publications and source records attributed to J Rueda.

At least 55 records · Page 3Linked to original sources
PubMed1995

Ultrastructural detection of glycogen in the supporting cells of the organ of Corti with the periodic acid-thiocarbohydrazide-silver proteinate method.

The glycogen content of several types of supporting cells in the organ of Corti of the rat was demonstrated histochemically at the ultrastructural level using the periodic acid-thiocarbohydrazide-silver proteinate method. The development of the glycogen stores was assessed by means of a semiquantitative method in normal and congenitally-hypothyroid rats. At birth, all the cell types of the developing organ of Corti showed in their cytoplasms numerous glycogen particles. As development proceeded, the density of glycogen particles increased, reaching the highest value at the 8th postnatal day for the cells of the organ of Kölliker, inner pillar cell and outer pillar cell. On the other hand, the peak of maximum glycogen content in Deiters' cells was accomplished at the 15th postnatal day. From the day in which the maximum value was obtained onwards, the glycogen content in all the cell types fell and disappeared. Congenital hypothyroidism induced by propylthyouracil only affected the normal development of the density of glycogen particles in Deiters' cells, which didn't undergo the increase observed in the normal animals, remaining at values similar to those obtained at birth. This finding, together with previous similar results on the glycogen content of the inner ear's outer hair cells suggest that hypothyroidism selectively impairs the development of those organ of Corti's cells which mature on the second postnatal week, in the rat.

Animals↗
PubMed1995

The protein phosphatase inhibitor calyculin-A affects catecholamine secretion and granular distribution in cultured adrenomedullary chromaffin cells.

Calyculin-A, a potent inhibitor of types 1 and 2A protein phosphatases, increases basal catecholamine secretion in cultured chromaffin cells with a maximum effect observed at 100 nM. This effect was increased by forskolin and the calmodulin antagonist W7, but was modified neither by phorbol esters nor the protein kinase inhibitor, H7. The effect of the toxin, calyculin-A, on basal secretion was completely prevented by the protein kinase inhibitor K252a. In digitonin-permeabilized cells calyculin-A induced an increase in basal release, but, in contrast, it partially reduced calcium-induced secretion. Analysis of total proteins revealed that calyculin-A treatment of the cells increased the level of phosphorylation of different protein bands. Examination of the Triton X-100-insoluble fraction revealed a clear increase in the phosphorylation level of various proteins, including vimentin. Calyculin-A provoked a rapid morphological change in chromaffin cells in the same range of concentration (50-300 nM). Cells became rounder and were partially detached from the substratum forming clusters, this effect was also blocked by K252a. Transmission electron microscopy of calyculin-A-treated cells showed an increase in the proportion of chromaffin granules located closer to the membrane. These results suggest that calyculin-A induces changes both in the catecholamine secretory response and in the cytoskeletal elements of chromaffin cells by protein phosphorylation.

Adrenal Medulla↗
PubMed1994

Pilocarpine-induced changes in the saccharide composition of the tectorial membrane and interdental cells of the organ of Corti: a study with gold-labeled lectins.

The glycoconjugates in the cytoplasm of inner ear interdental cells and those constituting the limbal tectorial membrane were identified by a post-embedding cytochemical method using low-temperature embedding in Lowicryl K4M and labeling with biotinylated lectins, goat anti-biotin antibody, rabbit anti-goat antibody, and gold-labeled protein A in control animals, and after the systemic injection of pilocarpine. The lectins used were ConA, PHA-E, PSA, RCA, SBA, Succ-WGA, UEA, and WGA. In control animals, a semiquantitive analysis of gold particles showed that Succ-WGA produced the strongest labeling on the tectorial membrane, followed by SBA, ConA, WGA, RCA, PHA-E, and PSA. The lowest values were obtained with UEA. The cytoplasm of the interdental cells was also labeled with all the lectins, but the number of particles/microns2 was lower than on the tectorial membrane. The concentration of gold particles on the limbal tectorial membrane in pilocarpine-treated animals was higher than in control animals for some lectins (RCA, PSA, UEA) but lower for others (WGA, SBA, PHA-E, Succ-WGA). The changes in the labeling pattern of the cytoplasm of the interdental cells paralleled those in the tectorial membrane. These results demonstrate that the saccharide composition of the limbal tectorial membrane can be modified by systemic injection of pilocarpine. This action may take place through a change in either the secretion rate or the amount of some glycoconjugates by the interdental cells.

Acrylic Resins↗
PubMed1993

Development of the tectal cells in the mouse cochlea.

Tectal cells appear at birth in the outer part of the developing organ of Corti. At first they are attached to the basilar membrane, but later they ascend through the auditory epithelium. During the 1st postnatal week (coinciding with the development of the minor tectorial membrane), the newly formed tectal cells show several cytological characteristics suggesting increased metabolic and secretory activities, which include: (1) a large Golgi complex, (2) abundant amorphous material inside the cisterns of rough endoplasmic reticulum, and (3) dense granules inside the mitochondrial matrix. All these features gradually disappear, and by the 14th postnatal day the tectal cells show a dark cytoplasm and few and short microvilli. In addition, tectal cells were stained selectively by some lectins. These findings suggest that tectal cells may participate in the secretion of some components of the minor tectorial membrane, different from those produced by Deiters' cells, Hensen's cells and pillar cells.

Animals↗
PubMed1992

Dissection of a pollen-specific promoter from maize by transient transformation assays.

We have previously reported the isolation and characterization of a gene (Zm13) from Zea mays which shows a pollen-specific pattern of expression. Stably transformed tobacco plants containing a reporter gene linked to portions of the Zm13 5' flanking region show correct temporal and spatial expression of the gene. Here we present a more detailed analysis of the 5' regions responsible for expression in pollen by utilizing a transient expression system. Constructs containing the beta-glucuronidase (GUS) gene under the control of various sized fragments of the Zm 13 5' flanking region were introduced into Tradescantia and Zea mays pollen via high-velocity microprojectile bombardment, and monitored both visually and with a fluorescence assay. The results suggest that sequences necessary for expression in pollen are present in a region from -100 to -54, while other sequences which amplify that expression reside between -260 and -100. The replacement of the normal terminator with a portion of the Zm13 3' region containing the putative polyadenylation signal and site also increased GUS expression. While the -260 to -100 region contains sequences similar to other protein-binding domains reported for plants, the -100 to -54 region appears to contain no significant homology to other known promoter fragments which direct pollen-specific expression. The microprojectile bombardment of Tradescantia pollen appears to be a good test system for assaying maize and possibly other monocot promoter constructs for pollen expression.

Gene Expression↗
PubMed1991

Pilocarpine elicits the interdental cell secretory activity of the inner ear.

Subcutaneous injection of pilocarpine in guinea pigs resulted in the following ultrastructural changes: 1) the apical cavities of the interdental cells were filled with a substance indistinguishable from the overlying amorphous layer of the TM; 2) a great number of spherical structures appeared over the limbal portion of the tectorial membrane. In TEM photomicrographs these structures displayed the same appearance as the amorphous layer of the TM and were usually continuous to it; 3) the number of holes that decorate the upper surface of the limbal portion of the TM was dramatically increased and it was found that they connect the endolymphatic space to the apical cavities of the interdental cells; 4) there was an increase in the number of the small extracellular vesicles found in the clear spaces of the tectorial membrane. These facts suggest that pilocarpine stimulates the secretion of the interdental cells, confirming the existence of the secretory processes previously described (Prieto et al., 1990). These findings can be related to the turnover of the TM in the adult animal and, perhaps, to the secretion of some organic compound to the endolymph. We postulate that the actions of pilocarpine on the interdental cells are most probably mediated by the activation of muscarinic acetylcholine receptors in these cells.

Animals↗
PubMed1990

Lectin staining of saccharides in the normal and hypothyroid developing organ of Corti.

Lectin staining has been used to detect mono- and oligosaccharides in normal and hypothyroid developing organs of Corti in the rat. Eight developmental stages were studied (1, 5, 8, 10, 15, 20, 50 and 60 days after birth). Congenital hypothyroidism was induced by oral administration of propylthyouracil to pregnant rats. Labelling of the tectorial membrane with 3 lectins, Ulex europaeus agglutinin-I (UEA-I), Lens culinaris agglutinin (LCA) and Ricinus communis agglutinin-I (RCA-I) showed no significant differences between normal and hypothyroid animals. Staining with peanut agglutinin (PNA) showed that the hypothyroid adult tectorial membrane (but not the normal one) possesses the disaccharide galactose + N-acetyl galactosamine. Phaseolus vulgaris agglutinin-L (PHA-L) labels the whole tectorial membrane in both groups of animals, but the staining is more intense in the hypothyroid one for a narrow band of oligosaccharide located just between the tectorial membrane and the underlying organ of Kölliker. Both soybean agglutinin (SBA) and succinylated wheat germ agglutinin (WGA) stain the tectorial membrane as well as the cytoplasm of the cells constituting the inner portion of the organ of Kölliker; this latter feature disappears in the normal animals about the 8th postnatal day, but it is abnormally preserved until the 60th postnatal day in the hypothyroid ones. In the adult hypothyroid animals, 3 of the lectins (LCA, PHA-L and WGA) stain extracellular conglomerates located under the synaptic pole of the outer hair cells.

Animals↗
PubMed1990

The effect of hypothyroidism on the development of the glycogen content of organ of Corti's hair cells.

The density of glycogen particles in organ of Corti's sensory cells was measured to determine the effect of congenital hypothyroidism upon the normal development of this energy source. This density in both normal and hypothyroid inner hair cells remains in low values from birth to adulthood. On the other hand, that of normal outer hair cells undergoes a great increase between the 10th and the 20th postnatal days, coinciding with the maturation of both the efferent innervation of these cells and the tuning properties of the auditory receptor. The glycogen stores of the hypothyroid outer hair cells do not show any significant increase from birth to adulthood. This latter fact suggests that the congenital hypothyroidism restrains the development of an important energy source of outer hair cells, most surely disturbing the physiological processes relying on glycogen metabolism.

Animals↗
PubMed1990

Two different secretion mechanisms in the inner ear's interdental cells.

Fixation with a mixture of tannic acid and glutaraldehyde reveals a darkly stained substance in the intercellular clefts between juxtapposed interdental cells, where it is included by pynocytotic vesicles. Over the interdental cells, similar-sized vesicles (35-45 nm) are present in clear spaces of the amorphous layer of the limbal portion of the tectorial membrane. Some images suggest that they may be secreted through small disruptions of the membrane of the interdental cells' microvilli. In addition, a TA-unstained, amorphous material is present inside both basal ducts and apical cavities of the interdental cells, thus suggesting another secretory route from the basal region of the interdental cells towards either the endolymph, or the tectorial membrane. These two secretion processes coexist in a single interdental complex, and the two secretion products may be involved in the turnover of the adult tectorial membrane and/or the secretion of some component of the endolymph.

Animals↗
PubMed1989

The effects of kainic acid on the cochlear ganglion of the rat.

The effects of locally applied kainic acid on cells and fibers in the rat cochlea were examined in a quantitative and ultrastructural study. Doses of 5 nM per microliter of artificial perilymph destroyed part of the spiral ganglion type I cell population, with no ototoxic effects on cochlear hair cells or supporting cells. Type II cells also appeared unaffected. A quantitative evaluation of the cell loss with the 5 nM dosage showed that 34% of spiral ganglion neurons were lost 10 days after treatment. Doses of 20 nM per microliters and 40 nM per microliters did not result in increasing neuronal loss. This differential toxicity could reflect the presence of a sub-population of spiral ganglion cells with an increased number of KA receptors.

Animals↗
PubMed1986

Subsurface material in outer hair cells.

Tannic acid stains a homogenous material inside the outer hair cells of the organ of Corti of the guinea pig. This material is always placed between the plasma membrane and the first layer of subsurface cisterns, but only in those areas along the lateral surface of the outer hair cell lining the spaces of Nuel. The possibility that this material is related to some particular function of outer hair cell lateral face is discussed.

Animals↗
PubMed1986

A Golgi study on the nucleus accumbens septi of the rat.

Golgi impregnations of one-month-old Wistar rats show 3 different neuronal types in the nucleus accumbens septi. These types could be clearly established on the basis of the size and shape of the soma and dendritic pattern; dendritic spines could not be used as a useful criterion for distinguishing among the 3 types. The type I neurons were the most widely distributed, while the giant type II cells are restricted to the ventral region. Type III neurons are fusiform cells; according to the axon branching, these neurons and those of type I may be interneurons.

Animals↗
PubMedDate not supplied

Neuronal loss in the spiral ganglion of young rats.

A quantitative study of spiral ganglion neurones was performed in rats during postnatal days 4, 5, 6, 30 and 60. There are 25,194 +/- 462 ganglion cells on postnatal day 4, abruptly falling to 18,809 +/- 514 on the 6th postnatal day. This neuronal loss accounts for the 22% of the overall ganglion cell population. The number of neurones remains almost unchanged from the 6th to the 60th postnatal day. This numerical variation in the neuronal population of the spiral ganglion seems to be related to the changes that take place during cochlear synaptogenesis, at the end of the first postnatal week, on the base of the outer hair cells. These changes involve competition among efferent endings approaching the cell and some afferents connected with it at birth, that disappear as a result of such a competition.

Animals↗