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M Cifuentes

Publications and source records attributed to M Cifuentes.

34 records · Page 2Linked to original sources
PubMed1996

Seasonal variation in the secretory activity of the subcommissural organ (SCO) of reptiles.

Seasonal variations in the secretory activity of the subcommissural organ (SCO) of snakes and turtles was studied by immunocytochemistry, lectins, and electron microscopy. In animals sacrificed in summer, immunoreactive material, mostly devoid of sialic acid, occupied the whole cytoplasm. Cells showed many distended cisternae of rough endoplasmic reticulum and secretory granules. In animals sacrificed in winter, patches of immunoreactive sialic acid-rich material occupied the apical cytoplasm. Cells lacked distended cisternae and the secretory granules formed clusters. These results suggest a decreased synthesis and release of secretory material in the SCO of lethargic reptiles.

Animals↗
PubMed1996

Bovine Reissner's fiber (RF) and the central canal of the spinal cord: an immunocytochemical study using a set of monoclonal antibodies against the RF-glycoproteins.

The subcommissural organ secretes N-linked complex-type glycoproteins into the cerebrospinal fluid. These glycoproteins condense to form Reissner's fiber (RF), which extends along the fourth ventricle and central canal of the spinal cord. A set of three monoclonal antibodies (Mabs 3E6, 3B1, and 2A5) has been obtained using these glycoproteins as immunogens. Competitive and sandwich enzyme-linked immunoassay methods have demonstrated that the three monoclonal antibodies are directed against different epitopes, and that there is no competition among them for their binding to glycoproteins of RF. Mab 3E6 displays immunoblotting properties that are similar to those of a polyclonal antibody against the pool of glycoproteins from RF, but that are different from those of Mabs 3B1 and 2A5. All three antibodies immunostain the bovine subcommissural organ and RF. A population of ependymal cells is stained by the polyclonal antibody, and Mabs 2A5 and 3E6, but not by Mab 3B1. The material present in a population of ependymal cells of the central canal, and the glycoproteins secreted by the subcommissural organ thus probably have partial chemical identity. Some evidence suggests that the immunoreactive ependymal cells are secretory cells. The luminal surface of the central canal is coated by a thin layer of material with immunocytochemical characteristics different from those of the ependymal cells; such a coat may correspond to material released from RF.

Animals↗
PubMed1996

Identification of a high molecular weight polypeptide in the subcommissural organ of the chick embryo.

The subcommissural organ is an ependymal brain gland that secretes, into the ventricular cerebrospinal fluid, high molecular weight glycoproteins that form Reissner's fiber. Precursor and processed forms of secretion have been demonstrated by immunoblotting in the subcommissural organ of mammals and fish. In the chicken only a processed form has as yet been identified. In the present report, we have studied the subcommissural organ of 13-day-old chick embryos using (1) an antiserum against bovine Reissner's fiber, and (2) the lectins, concanavalin A and Limax flavus agglutinin. Paraffin sections of the subcommissural organ and blots of subcommissural organ extracts have been analyzed. The ependymal cells of sectioned subcommissural organ are strongly stained with the antiserum. Concanavalin A binds to materials in all cytoplasmatic regions, whereas Limax flavus agglutinin identifies materials confined to the apex of the ependymal cells. In the blots, a band of 540 kDa is immunostained. This band is positive for concanavalin A positive but negative for Limax flavus agglutinin and is thereby regarded as representing a precursor form of the secretion.

Animals↗
PubMed1996

Ependymal denudation, aqueductal obliteration and hydrocephalus after a single injection of neuraminidase into the lateral ventricle of adult rats.

To investigate the role of sialic acid in the ependyma of the rat brain, we injected neuraminidase from Clostridium perfingens into the lateral ventricle of 86 adult rats that were sacrificed at various time intervals. After administration of 10 micrograms neuraminidase, ciliated cuboidal ependymal cells of the lateral ventricles, third ventricle, cerebral aqueduct, and the rostral half of the fourth ventricle died and detached. The ependymal regions sealed by tight junctions such as the choroid plexus and the subcommissural organ were not affected. Debris was removed by infiltrating neutrophils and macrophagic cells. At the same time, after ependymal disappearance, the aqueduct was obliterated. In this region, mitoses were evident and cystic ependymal cells were frequent. Hydrocephalus of the lateral and third ventricles was evident 4 days after neuraminidase injection. Gliosis was restricted to the dorsal telencephalic wall of the injected lateral ventricle. It is thought that cleavage of sialic acid from ependymal surface glycoproteins or glycolipids, likely involved in cell adhesion, led to the detaching and death of the ependymal cells. Thereafter, ependymal loss, together with edema, led to fusion of the lateral walls of the cerebral aqueduct and this in turn provoked hydrocephalus of the third and lateral ventricles. This model of experimental hydrocephalus is compared with other models, in particular those of hydrocephalus after viral invasion of the cerebral ventricles.

Age Factors↗
PubMed1996

Genuine ankylosing spondylitis in children: a case-control study of patients with early definite disease according to adult onset criteria.

OBJECTIVE: To describe a group of children with spinal and sacroiliac (SI) joint involvement since the initial year of disease, who fulfilled current adult onset ankylosing spondylitis (AS) diagnostic criteria within 3 years of onset. METHODS: We conducted a case-control study of 44 patients with juvenile onset definite AS. 14 cases (Group A) and 30 controls (Group B) were studied; groups were matched by age at onset (age < or = 16 years), duration of disease at the time of admission to our clinic (< or = 1 year), diagnostic criteria (New York criteria), and period of observation. We compare demographic characteristics, as well as peripheral joint disease 6 and 12 months after onset, and analyze Group A at time of diagnosis. In contrast to Group A, patients in Group B had a syndrome of peripheral arthritis and enthesitis (SEA syndrome), but no axial symptoms or definite diagnosis of AS in the first 5 years of disease. RESULTS: Patients in Group A were HLA-B27 positive boys with peripheral arthritis and enthesitis who differed from those in Group B in the frequency of pauciarthritis and polyarthritis at one year of disease (0 vs 36.7% and 100.0 vs 63.3%; p = 0.008) and age at diagnosis (9.03 +/- 1.13 vs 16.5 +/- 3.3 years; p > 0.0001). Six patients in Group A had lumbar pain and 3 SI joint pain 6 months after onset; at the end of the first year, the number increased to 10 and 6 patients, respectively. At time of diagnosis (2.36 +/- 0.72 yrs after onset), all patients in Group A had radiographic sacroiliitis and spinal, SI, and/or costosternal pain, 11 reduced anterior spinal flexion, and 6 reduced chest expansion. CONCLUSION: There is a less common subgroup of adult-like juvenile onset AS who develop clinical and radiographic evidence of disease affecting the axial skeleton earlier than children progressing from SEA syndrome to AS 5 to 10 years after onset.

Adolescent↗
PubMed1995

Antibody-mediated lysis of the bovine subcommissural organ maintained in culture.

The subcommissural organ (SCO) is a brain gland that secretes glycoproteins into the cerebrospinal fluid (CSF). It is an ancient and conserved secretory structure of the brain, developing very early in ontogeny. However, the function of the SCO is unknown. The secretory cells of the SCO are arranged into a single or double, irregularly shaped layer located at the interface of the CSF and nervous tissue. This has prevented its selective surgical destruction. The present investigation was designed to destroy the secretory cells of 30-day-old explants of bovine SCO by use of an immunological approach. A membrane preparation enriched with plasma membrane of the secretory cells of the bovine SCO was obtained. This preparation was further processed to separate the structural proteins. A similar procedure was applied to obtain a fraction of integral proteins of the plasma membrane of a nonsecretory ciliated ependyma. Antisera were prepared against both preparations of integral proteins. The antiserum against the fraction obtained from the SCO cells immunostained the plasma membrane of the bovine SCO cells and in immunoblot it reacted with several proteins of the membrane preparation from SCO cells. When added to the culture medium this antibody bound to the apical plasma membrane of the secretory ependyma of the bovine SCO kept in culture; it caused the lysis of these cells when used together with complement. None of these properties were displayed by the antiserum raised against the integral proteins of the plasma membrane of the ciliated ependyma. This antiserum, however, immunostained the bovine ciliated ependyma neighboring the SCO. These results indicate that immunological surgery of the SCO in living animals may be possible to achieve.

Animals↗
PubMed1995

Light- and electron-microscopic immunocytochemical investigation of the subcommissural organ using a set of monoclonal antibodies against the bovine Reissner's fiber.

Ten monoclonal antibodies (Mabs) against glycoproteins of the bovine Reissner's fiber (RF) have been used in a structural and ultrastructural immunocytochemical investigation of the bovine subcommissural organ (SCO) and RF. The SCO of other vertebrate species has also been studied. For comparison, polyclonal antibodies against bovine RF (AFRU) were used. The SCO and RF of ox, pig and dogfish and the SCO of dog, rabbit, rat and frog were submitted to light-microscopic immunocytochemistry using AFRU and Mabs. Postembedding ultrastructural immunocytochemistry was applied to sections of bovine SCO using AFRU and Mabs. Bovine SCO consists of ependymal and hypendymal cell layers, the latter being arranged as cell strands across the posterior commissure, or as hypendymal rosette-like structures. All cytoplasmic regions of the ependymal and hypendymal cells were strongly stained with AFRU. Six Mabs showed the same staining pattern as AFRU, one Mab stained RF strongly and SCO weakly, two Mabs stained RF but not SCO, and, finally, one Mab (3B1) exclusively stained the apices of the ependymal and hypendymal cells. All Mabs recognized the SCO and RF of the pig. Two Mabs bound to the SCO of the dog. One Mab stained the SCO of the rabbit and another the SCO of the rat. The SCO of frog and dogfish were totally negative. Bovine SCO stained with AFRU, showed label in the rough endoplasmic reticulum (RER) and the secretory granules (SG) of the ependymal and hypendymal cells. The former, in the form of parallel cisternae, reticulum or concentric rings, was seen throughout all cytoplasmic regions. SG were abundant in the apical pole of the ependymal and hypendymal cells. Only one Mab showed a staining pattern similar to AFRU. Five Mabs showed strong reactions in the SG but weak labeling of the RER. Mab 3B1 showed the label confined to the SG only. Our results suggest that: (i) in the bovine tissue, some epitopes are present in both precursor and processed materials, whereas others are characteristic of mature glycoproteins present in SG and the RF; (ii) the bovine SCO secretes at least two different compounds present in ependymal and hypendymal cells; (iii) both compounds coexist in the same secretory granule; (iv) there are conserved, class-specific, and species-specific epitopes in the glycoproteins secreted by the SCO of vertebrates.

Animals↗
PubMed1995

Autoimmune thyroid disease in primary Sjögren's syndrome.

PURPOSE: To evaluate the prevalence of autoimmune thyroid disease and thyroid dysfunction in patients with primary Sjögren's syndrome. PATIENTS AND METHODS: Thyroid function of 33 patients with primary Sjögren's syndrome was clinically and biochemically evaluated. Thyroid hormones and autoantibodies against thyroid peroxidase, thyroglobulin, and thyroid hormones were measured. RESULTS: Autoimmune thyroid disease and thyroid dysfunction were found in 15 cases (45%): autoimmune thyroiditis in 8 (24%); autoimmune hyperthyroidism in 2 (6%); and reversible iodine-induced hypothyroidism in the remaining 5 (15%). One or more of the evaluated autoantibodies were detected in 8 euthyroid patients (24%). Overall, the prevalence of autoantibodies against thyroid peroxidase, thyroglobulin, thyroxine, and triiodothyronine was 45%, 18%, 42%, and 36%, respectively. CONCLUSIONS: The high prevalence of autoimmune thyroid disease and thyroid dysfunction found in primary Sjögren's syndrome, using sensitive immunologic and thyroid function tests, suggest that both diseases are more frequently associated than it was previously thought, and should be sought clinically and by laboratory tests in all patients with primary Sjögren's syndrome.

Adult↗
PubMed1994

Decreased cerebrospinal fluid flow through the central canal of the spinal cord of rats immunologically deprived of Reissner's fibre.

The subcommissural organ is an ependymal brain gland that secretes glycoproteins to the cerebrospinal fluid (CSF) of the third ventricle. They condense to form a fibre, Reissner's fibre (RF), that runs along the aqueduct and fourth ventricle and the central canal of the spinal cord. A single injection of an antibody against the secretory glycoproteins of RF into a lateral ventricle of adult rats results in animals permanently deprived of RF in the central canal and bearing a "short" RF extending only along the aqueduct and the fourth ventricle. These animals, together with untreated control animals were used to investigate the probable influence of RF in the circulation of CSF in the central canal of the spinal cord. For this purpose, two tracers, (horseradish peroxidase and rabbit immunoglobulin) were injected into the ventricular CSF. The animals were killed 13, 20, 60, 120 and 240 min after the injection, and the amount of the tracers was estimated in tissue sections obtained at proximal, medial and distal levels of the spinal cord. In rats deprived of RF, a significant decrease in the amount of tracers present in the central canal was observed at all experimental intervals, being more evident at 20 min after the injection of the tracers. This suggests that lacking a RF in the central canal decreases the bulk flow of CSF along the central canal. Turbulences of the CSF at the entrance of the central canal of RF-deprived rats might explain the inability of the regenerating RF to progress along the central canal, as well as the reduced flow of CSF in the central canal of these animals.

Animals↗
PubMed1994

Analysis of the secretory glycoproteins of the subcommissural organ of the dogfish (Scyliorhinus canicula).

The subcomissural organ (SCO) is an ancient and conserved brain gland secreting glycoproteins into the cerebrospinal fluid which condense to form Reissner's fiber (RF). The SCO of an elasmobranch species, the dogfish Scyliorhinus canicula, was investigated applying morphological and biochemical methods. The SCO of 34 dogfishes were processed for the following techniques: (1) conventional transmission electron microscopy; (2) light and electron microscopy lectin histochemistry (Concanavalin A, Con A; wheat germ agglutinin, WGA; Limax flavus agglutinin, LFA); (3) light and electron microscopy immunocytochemistry using antisera raised against the glycoproteins of the bovine RF (anti-bovine RF), and the secretory material of the dogfish SCO (anti-dogfish SCO). The former reacts with the SCO of virtually all vertebrate species [19] (conserved epitopes); the latter reacts only with the SCO of elasmobranchs [Cell Tissue Res., 276 (1994) 515-522] (class-specific epitopes). At the light microscopic level both antisera immunoreacted selectively with the SCO and RF; no other structure of the central nervous system was reactive. Within the SCO the binding sites for WGA (affinity = glucosamine, sialic acid) and LFA (affinity = sialic acid) displayed the same density and intracellular distribution. At the ultrastructural level two types of granules were distinguished. Type I granules (200-400 nm) were numerous, reacted with both antisera, bound WGA but not Con A. Type II granules (0.8-1.8 microns) reacted with the anti-bovine RF serum but not with the anti-dogfish SCO serum, bound Con A and WGA. The content of dilated cisternae of the rough endoplasmic reticulum reacted with both antisera and bound Con A; it did not bind WGA. The SCOs of 4500 dogfishes were extracted in ammonium bicarbonate. This extract was used for SDS-PAGE and blotting. Blots were processed for immunolabeling using anti-bovine RF and anti-dogfish SCO sera, and for lectin binding (Con A, WGA and LFA). The anti-bovine RF revealed four compounds with apparent molecular weights of 750, 380, 145 and 35 kDa. The two former also reacted with the anti-dogfish SCO serum and bound Con A. Only the 380 kDa compound bound WGA and LFA. The findings indicate that both the conserved and the class-specific epitopes are part of the same compounds (780, 380 kDa), which would be stored in type I granules. The lectin binding properties of these compounds point to the 780 kDa compound as a precursor form and the 380 kDa polypeptide as a processed form.

Animals↗
PubMed1994

Myositis in primary Sjögren's syndrome. Report of 3 cases.

OBJECTIVE: To describe the findings and course of myositis in primary Sjögren's syndrome (SS). METHODS: We studied myositis in SS when clinically indicated. Of 104 patients with SS, we identified 3 cases. In all, the diagnosis was made according to clinical data, biochemical, electromyographic and biopsy criteria. Other autoimmune diseases were excluded. RESULTS: We found a prevalence of 3% of myositis secondary to SS. There were no significant associations between myositis and other clinical or laboratory variables. CONCLUSION: Although rare, myositis must be considered a part of the spectrum of SS. In our experience, treatment with steroids and immunosuppressive drugs was successful.

Adult↗
PubMed1992

Distribution of intraventricularly injected horseradish peroxidase in cerebrospinal fluid compartments of the rat spinal cord.

The circulation of the cerebrospinal fluid along the central canal and its access to the parenchyma of the spinal cord of the rat have been analyzed by injection of horseradish peroxidase (HRP) into the lateral ventricle. Peroxidase was found throughout the central canal 13 min after injection, suggesting a rapid circulation of cerebrospinal fluid along the central canal of the rat spinal cord. It was cleared from the central canal within 2 h, in contrast with the situation in the brain tissue, where it remained in the periventricular areas for 4 h. In the central canal, HRP bound to Reissner's fiber and the luminal surface of the ependymal cells; it penetrated through the intercellular space of the ependymal lining, reached the subependymal neuropil, the basement membrane of local capillaries, and appeared in the lumen of endothelial pinocytotic vesicles. Furthermore, it accumulated in the labyrinths of the basement membrane contacting the basolateral aspect of the ependymal cells. In ependymocytes, HRP was found in single pinocytotic vesicles. The blood vessels supplying the spinal cord were classified into two types. Type-A vessels penetrated the spinal cord laterally and dorsally and displayed the tracer along their external wall as far as the gray matter. Type-B vessels intruded into the spinal cord from the medial ventral sulcus and occupied the anterior commissure of the gray matter, approaching the central canal. They represented the only vessels marked by HRP along their course through the gray matter. HRP spread from the wall of type-B vessels, labeling the labyrinths, the intercellular space of the ependymal lining, and the lumen of the central canal. This suggests a communication between the central canal and the outer cerebrospinal fluid space, at the level of the medial ventral sulcus, via the intercellular spaces, the perivascular basement membrane and its labyrinthine extensions.

Animals↗
PubMed1990

Inhibition of adenylate cyclase by polyadenylate.

The effects of ribo- and deoxyribonucleic acids on the activity of detergent-dispersed adenylate cyclases from rat and bovine brain were examined. Mn2+ (10 mM)-activated adenylate cyclase was inhibited by micromolar concentrations of poly(A) (IC50 congruent to 0.45 microM). This inhibition was directly due to poly(A) and was not mediated by: (a) protein contamination of the poly(A) preparation, (b) metal chelation, (c) formation of an acid-soluble inhibitor of adenylate cyclase, (d) effects on the specific activity of [alpha-32P]ATP, (e) competition with MnATP for binding to adenylate cyclase, or (f) diversion of substrate to an alternate polymerase reaction. Inhibition of adenylate cyclase by poly(A) was on the enzyme's catalytic unit, as purified preparations of the enzyme from bovine brain were inhibited by poly(A). This inhibition by poly(A) was not likely mediated via the enzyme's "P"-site, through which activated forms of the enzyme are selectively inhibited by specific adenosine phosphates. In contrast with inhibition by the "P"-site agonist 3' AMP, inhibition of adenylate cyclase by poly(A) was slow in onset and was not reversible by dilution and showed a different metal-dependence. Inhibition of adenylate cyclase was relatively specific for poly(A) as poly(U) caused less than 50% inhibition and deoxyribonucleic acids had no effect. The potency and specificity of the inhibition of adenylate cyclase by poly(A) imply a biochemically interesting interaction that is possibly also of physiological significance.

Adenylyl Cyclase Inhibitors↗
PubMed1988

Immunocytochemical study of the hypothalamic magnocellular neurosecretory nuclei of the snake Natrix maura and the turtle Mauremys caspica.

An immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake Natrix maura and the turtle Mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. Arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. The same cells appeared to be stained by the anti-oxytocin-neurophysin and antimesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina termialis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunoreactive fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.

Animals↗
PubMed1987

Immunocytochemical and ultrastructural evidence for a neurophysinergic innervation of the subcommissural organ of the snake Natrix maura.

The subcommissural organ (SCO) of the snake Natrix maura was studied by use of the immunoperoxidase procedure. Primary antisera against bovine neurophysins (Nps I + II, OXY-Np), oxytocin (OXY), mesotocin (MST), arginine-vasotocin (AVT), somatostatin (SOM), beta-endorphin (END) and bovine Reissner's fiber were used. A conventional ultrastructural study, with special emphasis on the nerve fibers present in the SCO, was also performed. Nerve fibers containing immunoreactive OXY-Np and MST were seen to reach the SCO. The staining of adjacent sections with the anti-Reissner's fiber serum showed that the OXY-Np- and MST-immunoreactive fibers were distributed among the cell bodies and processes of the ependymal secretory cells. No fibers containing immunoreactive OXY, AVT, SOM or END were found in the SCO. The ultrastructural analysis revealed in the SCO the presence of nerve fibers filled with electron-dense granules, 170-210 nm in diameter. Although a direct apposition between these fibers and the SCO cells was frequently seen, no synaptic differentiations were identified. Structures identical to the Herring bodies (found in the neurohypophysis) were seen in the SCO.

Animals↗