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Biomedical subjects

R Pujol

Publications and source records attributed to R Pujol.

At least 127 records · Page 7Linked to original sources
PubMed1990

Auditory hair cells in human fetuses: synaptogenesis and ciliogenesis.

This paper brings together the most recent findings concerning the development of human fetus cochlear hair cells, as observed using transmission and scanning electron microscopy (TEM and SEM). Specific attention is drawn to the formation of synapses and the growth of stereocilia. In both types of hair cells, synaptogenesis begins before ciliogenesis (week 10 of gestation versus week 12). In the inner hair cell (IHC), an adultlike stage is seen around week 15 for synapses, but not before week 22 for stereocilia. In the outer hair cell (OHC), both synapses and stereocilia are not yet fully mature at week 22. Classic gradients of maturation are found: a base-to-apex gradient, and an IHC-to-OHC gradient. By comparing these results with the anatomical and functional data on cochlear development in laboratory mammals, the onset of cochlear function in the human fetus can be estimated to occur around week 18. The completion of cochlear maturation based upon the same anatomical criteria should occur about 10 weeks later.

Cilia↗
PubMed1990

Neurotoxicity of kainic acid in the rat cochlea during early developmental stages.

The neurotoxic effect of kainic acid (KA) was investigated by electron microscopy in rat cochleas at two developmental stages: 17 days of gestation (17 G) and postnatal day 1 (PN 1). In each animal, one cochlea was injected with 1 nmol KA diluted into 2 ml artificial perilymph, while the other cochlea was only injected with artificial perilymph as a control. Ten minutes later, the cochleas were perfused with fixative, removed and processed for electron microscopy. The KA injection resulted in marked swelling of the majority of afferent fibers, i.e. the peripheral processes of spiral ganglion neurons. In the 17 G cochlea, swollen fibers were traced from the perikarya to the undifferentiated otocyst epithelium. Following birth, swollen afferents in the PN 1 cochlea were in contact with both inner (IHCs) and outer hair cells (OHCs), which were now differentiated. At both stages of development, a subclass of small afferent nerves were unaffected. At PN 1, the KA-insensitive afferents only contacted the OHCs. These fibers probably belong to the spiral system of afferents and are related to type II spiral ganglion cells. Conversely, KA-sensitive afferents probably belong to the radial system, related to type I spiral ganglion cells. This system is specific for IHCs in adult cochleas and appears to innervate both IHCs and OHCs at early developmental stages. These findings also indicate that KA neurotoxicity appears very early in the cochlea, at a prenatal time (17 G) before the presynaptic partners of afferent terminals (namely the IHCs) are differentiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1990

Ototoxic and nephrotoxic drugs inhibit agonist-induced inositol phosphate formation in rat brain synaptoneurosomes.

Neomycin (an aminoglycoside antibiotic), ethacrynate (a loop diuretic), cisplatin (an anticancer drug) and mercuric chloride are chemically unrelated drugs which present similar ototoxic and nephrotoxic properties. We have found that all these molecules inhibit inositol phosphate turnover induced by carbachol or glutamate in rat brain synaptoneurosomes. Since this second messenger system appears to be a key mechanism for cell functioning and even survival, our observations raise the possibility that the expression of the specific toxicity of these compounds may result from excessive inhibition of the phosphoinositide cascade.

Animals↗
PubMed1990

Glutamate neurotoxicity in the cochlea: a possible consequence of ischaemic or anoxic conditions occurring in ageing.

Glutamate is considered to be one of the most common neurotransmitters in the fast excitatory synapses in the central nervous system. On the other hand, its excitotoxic properties are increasingly cited to explain some of the brain damage linked with hypoxia and ischaemia: i.e., those that occur frequently in ageing. An excess release of glutamate could, either directly or indirectly, activate receptors on the postsynaptic neuron, causing ion influxes accompanied by a massive entry of water, which would lead to an acute swelling of dendrites. In addition, calcium influx deregulates calcium homeostasis, which could lead to cell death. In the cochlea, glutamate is now considered to be one of the best candidates to mediate neurotransmission between inner hair cells (IHCs) and the auditory nerve dendrites. Among the variety of anatomical and physiological findings supporting the glutamate hypothesis, is the striking similarity of acute damage in the organ of Corti caused by exposure to a glutamate analogue (kainic acid), or by hypoxia, or even by an intense loud noise. In all cases an immediate swelling is observed, specifically affecting the radial afferents below the IHCs. The best explanation for this swelling is related to glutamate (or glutamate analogue) excitotoxicity. Thus, some of the cochlear damage that occur with ageing, especially the loss of the radial afferent fibres and type I ganglion cells, might well be attributed to glutamate excitotoxicity linked to vascular atrophy. The present paper discusses this hypothesis.

Aging↗
PubMed1990

[Factors associated with generalized forms of arteriosclerosis in patients with coronary disease].

We studied the lipidic metabolism and the atherogenic risk factors non related to lipidic metabolism in two groups of patients: group 1 with only coronary disease and group 2 with coronary disease and atherosclerosis in the cerebral and/or peripheric artery territories. Patients of group 2 showed a cholesterol, cLDL, and B-apoprotein titers significantly higher than group 1. Systolic and diastolic blood pressure were higher in group two. Also the incidence of diabetes mellitus in group 2 was higher than in group 1. In a stepwise discriminating analysis the diastolic arterial pressure and cholesterol titers were the parameters with a greatest predictive potential for the presence of localized or generalized ischemic disease. B-apoprotein was the lipidic parameter with the greatest predictive potential. All together these data suggest that in coronary patients, a discrete increase in plasma cholesterol can imply a risk of suffering ischemia in some other arterial territories. Diastolic blood pressure, cholesterol and diabetes mellitus are the factors with the highest predictive potential for the generalization of arteriosclerosis.

Arteriosclerosis↗
PubMed1990

Repeated exposure to ultraviolet A in polymorphous light eruption patients and normal subjects: a clinical and histopathological study.

The clinical and histopathological responses to repeated exposures of ultraviolet A were studied in patients with polymorphous light eruption and in normal controls. Variable degrees of perivascular and diffuse infiltrates (lymphocytic and neutrophilic) were detected in both groups. These findings indicate that more specific parameters should be used to distinguish reactive from pathological responses.

Adult↗
PubMed1990

[Tubular apocrine adenoma. Description of 4 cases].

We present four new cases of tubular apocrine adenoma. Clinical histopathological and ultrastructural findings are discussed. The presence of carcinoembryonic antigen (CEA) has been studied in three cases of tubular apocrine adenoma. This antigen was found predominantly in the lumen of the ducts and in the apical portion of the luminal cells. This pattern is similar to the distribution described in normal sweat glands and in other adnexal tumors.

Adenoma↗
PubMed1990

[Cochlear physiology and physiopathology. Recent data].

Our concept of cochlear physiology has changed so drastically over the last decade that most classical textbooks have become obsolete. This bibliographical inadequacy regarding the functioning of the normal cochlea is particularly disturbing when it comes to addressing patho-physiology problems (hearing loss or tinnitus). What drastic changes have there been, that can justify such need for information updating? These relate primarily to the role of one the two types of sensory cells of the cochlea; i.e., the outer hair cells (or OHC). These cells are endowed with contractile properties and react to tonal impulse by modifying the vibration of the cochlear partition. This "active mechanism" response provokes a localized amplification of the vibration imparting to these classical sensory transducers, or inner hair cells (IHC), their optimal frequency sensitivity and discrimination properties. This new concept alone would suffice to justify our present topic. We chose, however, to insert a general presentation of cochlear physiology, the intent of which is to briefly review the classical data and to analyze in some depth the issues that have drastically changed our knowledge.

Cochlea↗
PubMed1989

[Vesiculopustular eruption and Sweet syndrome associated with 2 exacerbations of ulcerous colitis in a 76-year-old woman].

The concept of acute febrile neutrophilic dermatosis (Sweet's syndrome) has evolved and expanded to include, under the denomination of neutrophilic dermatosis (ND), both pyoderma gangrenosum and the intestinal bypass syndrome, with or without intestinal bypass, vesicular and pustular rash associated with ulcerative colitis (UC), and Sweet's syndrome itself. Among the skin lesions associated with UC several types of vesicular and pustular rash have been reported and, very rarely, the association of UC and Sweet's syndrome has been reported. We report a female with UC who developed a vesicular and pustular rash associated with an exacerbation of her colonic disease. Two years later she developed a characteristic Sweet's syndrome coincident with another exacerbation of UC. The concurrence of two different forms of ND associated with successive exacerbations of UC supports the concept of ND as an individual condition with several types of clinical presentation.

Aged↗
PubMed1989

Appearance of B and H blood group antigens in the developing cochlear hair cells.

The presence of human blood-group antigens was analyzed in the rat cochlea during its postnatal development, using anti-A, anti-B and anti-H antibodies. At no stage was reactivity with anti-A antibody observed. With the anti-H antibody, a strong reactivity was observed from 1 to 9 days after birth within hair cells and some other surface epithelial cells of the cochlear duct. After postnatal day 9, only a faint reactivity persisted in a few non-sensory cells. With the anti-B antibody, only hair cells were selectively labeled. At early stages (postnatal day 1 and 3), the reactivity was intense and observed both around the cell surface and within the supranuclear region of cytoplasm. Later on, the reactivity decreased; it was limited at postnatal day 9 to a reactive spot below the cuticular plate. Results are compared with a preliminary finding describing the first appearance of B and H antigens in the organ of Corti at a prenatal stage, and with data concerning other sensory and neural structures. The appearance and progressive disappearance of B and H antigens on sensory and non-sensory cells can be correlated with significant events in the development of the cochlea. The transient expression of B and H antigens in cochlear sensory cells may correspond to developmental changes in their surface glycoconjugates.

ABO Blood-Group System↗
PubMed1989

Nucleolar structures in chromosome and SC preparations from human oocytes at first meiotic prophase.

We describe a comparative study of the behavior of nucleolar structures and their relationship with nucleolar chromosomes and synaptonemal complexes at first meiotic prophase of human oocytes in an attempt to elucidate the nature of this cellular organization and to learn more about maternal nondisjunction. The number of main nucleoli varies along the different stages of prophase I and is usually low. It shows an increase from leptotene to pachytene and a decrease from pachytene to diplotene related to a decrease and an increase of main nucleoli volume, respectively. The methodology employed has enabled us to analyze in detail dark bodies, round bodies, dense bodies, and main nucleoli in chromosome or synaptonemal complex spreads. The relationship between nucleolar chromosomes or synaptonemal complexes and the nucleoli implies the existence, in a very reduced space, of chromosomal regions that contain homologous sequences and that are often unpaired. This situation may facilitate the production of heterologous pairing and chromosomal exchanges between nonhomologous chromosomes and finally result in aneuploidy. Thus, the situation explained above together with the differences between the oocyte and spermatocyte NOR cycles could be one of the reasons for the higher incidence of aneuploidies of maternal origin at meiosis I.

Cell Nucleolus↗
PubMed1989

Cochlear neuroactive substances.

We have reviewed the experiments done in our laboratory concerning various cochlear neuroactive substances. Data using chemical neuroanatomy and neurochemical techniques are described. They allow the identification and localization of neuroactive substances which could act as neurotransmitters and/or neuromodulators at the different types of synapses in the organ of Corti. Three hypotheses are presented: (1) the inner hair cells use glutamate as a neurotransmitter, but in addition to its excitatory properties, glutamate may also be involved in pathophysiological events affecting afferent auditory dendrites: (2) subpopulations of both the lateral and medial olivocochlear efferent systems can be differentiated by the neuroactive substances they may use: (3) the base and the apex of the cochlea can be distinguished on the basis of neurochemical data.

Animals↗
PubMed1988

Sequential study of the synaptonemal complex in rat (Rattus norvegicus) oocytes by light and electron microscopy.

The progression of first meiotic prophase and synaptonemal complex (SC) formation in female rats, Rattus norvegicus S.D., is described through the analysis of the different stages of the first meiotic prophase, and confirms the high synchrony of the process in this species. Leptotene is a stage of very short duration and since pairing of the homologues begins very early, only a leptotene-zygotene stage can be distinguished. The progression of pairing during zygotene is asynchronous. The morphology of the SCs is similar to that described in other species. During diplotene and before disintegration of the lateral elements, desynapsis takes place. In some oocytes a double or even multiple nature of lateral elements was seen. Associations between SCs and nucleoli or nucleolar filaments are frequent. The presence of fragmented SCs can be interpreted as a technical artifact.

Animals↗