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M Geffard

Publications and source records attributed to M Geffard.

At least 55 records · Page 3Linked to original sources
PubMed1994

Baroreceptor-aortic nerve-mediated release of endogenous L-3,4-dihydroxyphenylalanine and its tonic depressor function in the nucleus tractus solitarii of rats.

We have proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter and/or neuromodulator in the central nervous system [Misu Y. and Goshima Y. (1993) Trends pharmac. Sci. 14, 119-123]. This study aimed to explore whether or not endogenous L-DOPA, as a neurotransmitter candidate of the primary baroreceptor afferents, tonically functions to activate depressor neurons in the nucleus tractus solitarii of anesthetized rats. By parallel microdialysis in bilateral nucleus tractus solitarii areas, the basal L-DOPA release was in part inhibited by tetrodotoxin perfusion (1 microM) or Ca2+ deprivation, and was markedly reduced by alpha-methyl-p-tyrosine (200 mg/kg, i.p.), a tyrosine hydroxylase inhibitor. Forty to 100 mM K+ concentration-dependently released L-DOPA. Fifty millimoles K+ repetitively and constantly released L-DOPA. This release was Ca(2+)-dependent. Stimulation of the left aortic nerve (100 Hz, 8 V) repetitively and constantly released L-DOPA and this release was tetrodotoxin-sensitive. Phenylephrine i.v. infused produced L-DOPA release and reflex bradycardia, temporally associated with a rise and subsequent recovery of blood pressure. This release and bradycardia were abolished by denervation of the bilateral carotid sinus and aortic nerves. In addition, L-DOPA methyl ester, a competitive L-DOPA antagonist, when microinjected into depressor sites of the left nucleus tractus solitarii, antagonized depressor responses to mild stimulation (20 Hz, 3 V) of the ipsilateral aortic nerve. This antagonist alone, microinjected bilaterally, elicited a dose-dependent hypertension, which was abolished by alpha-methyl-p-tyrosine. Furthermore, by immunocytochemical analysis seven days after denervation of the left aortic nerve, tyrosine hydroxylase- and L-DOPA-, but not dopamine- and dopamine-beta-hydroxylase-immunoreactivities decreased in the ipsilateral nucleus tractus solitarii and dorsal motor vagus nucleus complex area. In the left ganglion nodosum, denervation decreased staining and number of L-DOPA-immunoreactive cells and staining of tyrosine hydroxylase-immunoreactive cells, but no modification of dopamine-immunoreactive cells was seen. Taken together with previous findings that L-DOPA itself is stereoselectively responsible for cardiovascular control in this nucleus, it is probable that L-DOPA is a neurotransmitter of the primary baroreceptor afferents terminating directly in depressor neurons and/or indirectly in some neurons within a microcircuit, including depressor neurons of the nucleus tractus solitarii. Endogenously released L-DOPA itself tonically functions to activate depressor neurons for regulation of blood pressure in the rat nucleus tractus solitarii.

Animals↗
PubMed1994

Curative effects on rat sarcomas obtained after a treatment combining two monoclonal antibodies.

The effects of a treatment involving two monoclonal antibodies (Ab) were evaluated on benzo(a)pyrene [B(a)P]-induced malignant sarcomas in Sprague-Dawley female rats. These Ab were, respectively, an anti-anti-conjugated B(a)P AB, an internal image of conjugated B(a)P, called AIB1, and an anti-conjugated L-DOPA Ab. They were biweekly injected into animals with small clinically palpable tumors. Anti-'phosphatidylinositol-like' autoantibody (autoAb) levels which were significantly higher in B(a)P-treated rat sera were decreased after Ab treatment. Tumor growth was slowed down compared with that of controls and animal survival was increased. This treatment was more efficient than that involving AIB1 alone. The anti-conjugated L-DOPA Ab may play a role in neovascularization, which is known to be critical for tumor growth.

Animals↗
PubMed1994

Circulating autoantibodies directed against conjugated fatty acids in sera of HIV-1-infected patients.

Several reports have demonstrated that major changes occur in the fatty acid content of HIV-infected cells. In order to evaluate if these changes are recognized by the immune system, we have attempted to assay the possible presence of autoantibodies (autoAb) directed against conjugated fatty acids (CFA). Using an adapted ELISA, anti-CFA autoAb were assayed in sera of 150 HIV-1-infected patients and 116 controls (healthy donors and patients suffering from other diseases). Significantly increased anti-CFA autoAb of IgG class were found in HIV-1-infected patients (alpha < 0.001). Using our ELISA method and CFA differing in their length and their degree of unsaturation (lauric, myristic, palmitic, palmitoleic, stearic, oleic, linolenic, linoleic, lignoceric, arachidonic, eicosapentaenoic and docosahexaenoic acids), it was demonstrated that the acyl chain of CFA is the immunodominant part recognized by these autoAb. Anti-CFA autoAb were present in 15/52 asymptomatic carriers, 14/36 symptomatic carriers, 16/39 ARC patients, but only 3/23 AIDS patients. Anti-CFA activity seemed to be linked with the CD4+ T cell count, and was not related to the total IgG amounts. Anti-CFA autoAb could result from self-antigen presentation to immunological cells, and may reflect lipid membrane modifications occurring in HIV-infected cells.

Autoantibodies↗
PubMed1994

Adrenergic innervation of the urinary bladder body in the cat with special reference to structure of the detrusor muscle: an immunohistochemical study of noradrenaline and its synthesizing enzymes.

The distribution of adrenergic nerves in the body detrusor muscle of the cat urinary bladder was studied by means of the immunohistochemical identification of noradrenaline (NA) and the NA synthesizing enzymes tyrosine hydroxylase, aromatic L-aminoacid decarboxylase and dopamine beta-hydroxylase. We identified the basic structural organization of the detrusor muscle, which had previously been described as lacking discernible layers. In the lateral wall, both outer longitudinal and inner circular muscle bundles were present, the latter extending in both anterior and posterior directions. The posteriorly running bundles came to lie on the outside of the posterior wall where they enabled recognition of inner longitudinal muscle bundles. Those running anteriorly were dispersed to enter the longitudinal bundles in the anterior wall. NA-immunoreactive nerve fibers in the detrusor muscle of the bladder were found to be similar to those immunoreactive for NA synthesizing enzymes in both distribution and density. In the upper and middle bladder body--including the dome (apex)--immunoreactive nerve fibers were always more abundant in the outer part of the detrusor muscle than in the inner part, regardless of the course of muscle bundles. Even in individual muscle bundles running from the inside to the outer surface, the outer part was more richly innervated by immunoreactive fibers than the inner part. In the bladder dome, a moderate number of immunoreactive nerve fibers preferentially innervated the outer part of the muscle layer. In the lower bladder body, these nerve fibers increased in density in the inner part of the detrusor muscle. There was no sexual difference in density or distribution of nerve fibers. NA- and NA synthesizing enzyme-immunoreactive nerve fibers were markedly decreased in number after 6-hydroxydopamine treatment. No dopamine- or phenylethanolamine-N-methyltransferase-immunoreactive nerve fibers were present in the bladder. The findings of this study indicate that the cat bladder musculature includes longitudinal and circular muscle bundles, both of which are extensively innervated by adrenergic nerves, particularly in the outer part of the bladder.

Adrenergic Fibers↗
PubMed1993

Radioimmunoligand characterization and immunohistochemical localization of dopamine D2 receptors on rods in the rat retina.

The retinal neurotransmitter dopamine (DA), elaborated from intrinsic dopaminergic neurons as amacrine and interplexiform cells, is known to modulate several complex functions mediated by D1 and D2 receptors in the vertebrate retina. In this paper, we characterized and localized DA receptors of the D2 family on rod outer segments (ROS) of the rat retina by a radioimmunoligand binding assay and by immunohistochemistry. Anti-anti-DA conjugated antibodies (or anti-idiotypic antibodies Ab2) were used as ligand; BSA-glutaraldehyde-conjugated spiperone, eticlopride (D2 antagonists) and DA were used as displacers. The linear Scatchard transformation indicated that data were best fit to the one-site model. By using the peroxidase-antiperoxidase technique, an intense labeling was located on rods. These results supported the paracrine action of DA on the photoreceptor cell.

Animals↗
PubMed1993

A monoclonal anti-idiotypic antibody with an internal image of a "phosphatidylinositol-like" structure derived from anti-"phosphatidylinositol-like" IgG from the sera of patients with proliferative malignancies.

Using an enzyme-linked immunosorbent assay (ELISA) with phosphatidylinositol (PtdIns) coated on well-plates, high levels of anti-"PtdIns-like" autoantibodies (autoAbs) have been previously described in sera of cancer patients. These anti-"PtdIns-like" autoAbs were purified and injected into BALB/c mice. A monoclonal anti-idiotypic antibody (Ab2), internal image of human endogenous "PtdIns-like" structure called AIPI, was selected. Then the immunological binding in sera of cancer patients was evaluated on AIPI coated on well-plates. Using this indirect ELISA method, we found a statistically highly significant immunological binding in sera of patients with epithelial tumors, which correlated with that previously found with the PtdIns molecule coated on well-plates. Moreover, AIPI mimics an endogenous structure closely associated with PtdIns specifically encountered in epithelial proliferative disease.

Animals↗
PubMed1993

Identification of tryptamine and tryptamine-serotonin neurons in the rat dorsal raphe nuclei using specific antibodies.

Previous studies have shown that tryptamine (T) is closely associated with the serotonergic system but have failed to determine whether neurons containing only T exist in the raphe nuclei (RN) and/or if T colocalizes with serotonin (5-HT). The use of rabbit-conjugated T antisera (TAS) and rat-conjugated 5-HT antisera (5-HTAS) in a double-labelling technique has made the study of the colocalization of T and 5-HT in neurons of the rat dorsal RN (DR) possible. Slices taken from the same zone of the DR were treated following four different procedures of double-immunolabelling: DAB coloration for the rabbit TAS and DAB-nickel coloration for the rat 5-HTAS either first or second; or DAB coloration for the 5-HTAS and DAB-nickel coloration for the TAS first or second. Control sections were treated according to a single immunoperoxidase staining in the same zone. The immunolabelled neurons were computed using the Biocom 200 program at the same magnification. The results of this double-immunolabelling show that three different cell types exist in the rat DR: (1) T-only-containing neurons, (2) 5-HT-only-containing neurons displaying either homogeneous DAB or homogeneous DAB-nickel, and (3) neurons where T colocalizes with 5-HT (T-positive/5-HT-positive neurons) displaying heterogeneous DAB-nickel coloration. The results were identical whatever the procedure performed or the order of the DAB-nickel revelation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Evidence for nonsynaptic serotonergic and noradrenergic innervation of the rat dorsal horn and possible involvement of neuron-glia interactions.

We investigated the synaptic incidence of the contacts established by serotonergic and noradrenergic descending fibers in the dorsal horn of the rat spinal cord. Serial electron microscopic sections were performed. Synapses were scarce. The majority of serotonergic and noradrenergic varicosities (more than 60%) are characterized by nonsynaptic contacts. Numerous glial profiles, and particularly astrocytic profiles, were observed in apposition with serotonergic and noradrenergic varicosities. The proportion of astroglia was higher around serotonergic and noradrenergic varicosities devoid of synaptic specialization. The length of the contact between immunoreactive nonsynaptic varicosities and astrocytes was twice as long as that between synaptic varicosities and astrocytes. Thus, the modulation of sensitive messages by serotonin and noradrenaline through pauci-synaptic varicosities in the dorsal horn of the spinal cord could be an example of the concept of "volume transmission" [Fuxe and Agnati (1991) Volume Transmission in the Brain: Novel Mechanisms for Neural Transmission, Advances in Neuroscience, Vol. 1, pp. 1-9.] in the central nervous system. Analysis of the microenvironment of serotonergic and noradrenergic varicosities led us to make the hypothesis that glial cells, particularly astrocytes, could play some role in volume transmission.

Animals↗
PubMed1993

Expression of dopamine by chick primary sensory neurons and their related targets.

The expression of dopamine by primary sensory neurons and their peripheral projections was studied in the chick dorsal root ganglion by means of immunocytochemical procedures. Within the sensory neurons, dopamine immunoreactivity is first expressed by 0.8% of cells at E10 and reaches a percentage of 5.6% before hatching. After hatching, 8.6% of neurons, belonging to both the A and B classes of sensory neurons, exhibit a clear immunostaining. According to the immunostaining of nerve terminals located in various peripheral target tissues, these immunoreactive neurons are responsible, at least in part, for the sensory innervation of the skin and paravertebral ganglia. The results provide evidence that different classic neurotransmitters may be expressed by specific subpopulations of primary sensory neurons expressing various somatic and autonomic sensory functions in relation to specific targets.

Animals↗
PubMed1993

Seric immune complexes in multiple sclerosis do not contain MBP epitopes.

Immune complexes from sera of MS patients, other neurological diseases, and healthy donors were precipitated using polyethyleneglycol and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Silver staining evidenced additional protein bands whose molecular weights were 14-16, 38, and 43 kDa. These IC proteins were present in most MS patients studied. To identify their nature, immunoblotting was performed with antihuman immunoglobulins A, M, G antibodies. No immunoreactivity was found below a molecular weight of 66 kDa on a nitrocellulose sheet having the transferred protein pattern of MS IC. Using purified human myelin, MS IC transferred to an immobilon sheet and antihuman myelin basic protein antibodies, an immunoreactivity was seen only on purified human MBP. The small proteins of 14-16 kDa and the others of 38, 43 kDa were not immunoreactive. Identification of the nature of these additional proteins in MS IC is in progress.

Antigen-Antibody Complex↗
PubMed1993

[Effects of monoclonal anti-idiotypic antibody, internal image of benzo(a)pyrene on sarcoma in rats].

The effects of a monoclonal anti-idiotypic antibody (Ab), internal image of conjugated benzo(a)pyrene [B(a)P], called AIB1, on B(a)P-induced malignant sarcomas in Sprague-Dawley (SD) female rats were evaluated at different times after B(a)P-administration. As previously described, circulating anti-"phosphatidylinositol (PtdIns)-like" autoantibody levels were found to be significantly higher in B(a)P-treated rat sera. They were decreased after AIB1 Ab-treatment. Furthermore, the tumor growth was slowed down compared with that of controls and animal survival was slightly increased. These results showed the relationships between metabolic pathways involving possible "B(a)P-like" endogenous ligand/cytosolic receptor(s) and the PtdIns.

Animals↗
PubMed1992

Spinal dopaminergic system of the rat: light and electron microscopic study using an antiserum against dopamine, with particular emphasis on synaptic incidence.

The mapping of the spinal dopaminergic innervation has been performed in the adult rat using an anti-dopamine antiserum. Immunoreactive fibers were detected with the light microscope in the dorsal horn (mainly in laminae III-IV), in the intermediolateral cell column (IML), in the peri-ependymal region and in the ventral horn. The ultrastructural analysis of dopaminergic innervation showed mainly axodendritic contacts and fewer axosomatic ones. In the ventral horn and the IML, the pattern of dopaminergic innervation exhibited a majority of classical synapses. In the dorsal horn, dopaminergic innervation was partly non-synaptic (at cervical level), whereas numerous axodendritic synapses were observed at thoraco-lumbar level. Previous studies described the non-synaptic organization of serotonergic and noradrenergic projections in the dorsal horn. It is thus hypothesized that the monoaminergic systems, involved in pain modulation within the dorsal horn, act partly through volume transmission. In contrast, these systems would modulate the motor and autonomic functions through classical synapses.

Animals↗
PubMed1992

Dopaminergic neurons in the cat dorsal motor nucleus of the vagus, demonstrated by dopamine, AADC and TH immunohistochemistry.

In the rostral part of the dorsal motor nucleus of the vagus of the cat, neurons do not contain histochemically detectable catecholamines, even though many perikarya contain both intense aromatic L-amino acid decarboxylase (AADC) immunoreactivity and strong monoamine oxidase enzymatic activity. Similarly located perikarya have distinct immunoreactivities to tyrosine hydroxylase (TH) and dopamine after treatment with colchicine. Since inhibition of monoamine oxidase fails to reveal dopamine in these cells, its absence in non-colchicine-treated animals cannot be due to rapid deamination. It appears that dopamine is synthesized by TH and AADC in dorsal motor vagal cells and is then rapidly transported from the perikarya.

Animals↗
PubMed1992

Anti-phosphoinositide auto-antibodies in sera of cancer patients: isotypic and immunochemical characterization.

High levels of circulating anti-phosphatidylinositol (PtdIns) auto-antibodies (auto-Ab) have been previously found in sera of patients with malignant tumors. Using our ELISA test, a high statistical level of immunological binding directed against PtdIns was found in a large series of sera from patients with proliferative pathologies. In contrast to tumor markers, anti-PtdIns auto-Ab did not vary whatever the histological grades, TMN classification and patient's age. These anti-PtdIns auto-Ab were immunoglobulins (Ig) of G class. Their specificity was evaluated by competition experiments in ELISA and found to be rather high. An increase of these circulating auto-Ab reflected possible disturbances in PtdIns turnover and appearance of endogenous neo-antigen with PtdIns structure.

Antibodies, Neoplasm↗
PubMed1992

Pre- and postnatal development of noradrenergic projections to the rat spinal cord: an immunocytochemical study.

Using immunocytochemistry with a specific antiserum against noradrenaline, the pre- and postnatal development of noradrenergic (NA) projections to the rat spinal cord was studied from embryonic day 16 (E16) to adulthood (the day following nocturnal mating being considered as E0). In this study, pregnant animals were pre-treated with the MAO inhibitor pargyline (200 mg/kg i.p.), whereas postnatal animals received 100 mg/kg. In vibratome sections, noradrenaline-immunoreactive (NA-IR) axons were seen to invade the spinal cord at E16, at cervical and upper thoracic levels, from the ventral funiculus. At E18, small caliber NA-IR fibers were present in the ventral horn at all cord levels, and some fibers were seen in the intermediolateral cell column (IML) at thoracic level. The growth of axons towards the dorsal horn became noticeable by postnatal day 0 (P0). At P3, fine beaded and radially orientated NA-IR fibers were observed at all levels. The pattern of NA innervation of the dorsal horn was similar to that of the adult by P7. The segregation of noradrenaline immunoreactivity in the ventral and dorsal horns, the IML and the periependymal area was more obvious at all levels by P14 and P20. From P30 the NA innervation was similar to that found in the adult spinal cord. Thus, noradrenaline, like serotonin, was present early in the spinal cord before the onset of specific functions. In addition to and prior to its transmitter function, it might play a trophic role in the neurogenesis of the spinal cord.

Aging↗
PubMed1992

Identification and characterization of a specific autoantiphosphatidylinositol immune response during the time course of benzo(a)pyrene-induced malignant tumors in female Sprague-Dawley rats.

High levels of anti-phosphatidylinositol (PtdIns) autoantibodies (autoAb) have been previously described in sera of cancer patients and in plasma of dimethylbenzanthracene-treated female Sprague-Dawley rats. The presence of anti-PtdIns autoAb was tested in a model of highly malignant sarcomas induced by a single dose of benzo(a)pyrene [B(a)P] diluted in sesame oil and injected in female Sprague-Dawley rats. Significantly elevated levels of anti-PtdIns autoAb were found in sera of B(a)P-treated rats 40 days after B(a)P administration, whereas no significant levels of anti-PtdIns autoAb were noted in oil- or benzo(e)pyrene-treated rats. After day 60, autoantibody levels plateaued in B(a)P-treated rats, and highly malignant sarcomas appeared with 100% efficiency around day 100. Anti-PtdIns autoAb avidity and specificity were found to be high.

Animals↗
PubMed1992

Serotoninergic, noradrenergic, and peptidergic innervation of Onuf's nucleus of normal and transected spinal cords of baboons (Papio papio).

We have investigated with light and electron microscope immunocytochemistry the aminergic and peptidergic innervation of Onuf's nucleus in adult baboons. This nucleus, located in the ventrolateral part of the sacral spinal cord (S2 and S3), is considered to control urethral and anal sphincters and penile muscles. By comparison of intact and transected spinal cords, we have found that serotoninergic innervation has two origins: first, supraspinal, innervating the whole nucleus, with a possible predominance in the dorsal half; and second, intraspinal, corresponding to the ventral half of the nucleus. Thyrotropin-releasing hormone innervation appears largely coincident with serotonin, both in intact and transected spinal cords. Noradrenaline is exclusively of supraspinal origin, as attested by its disappearance below the level of the section. Substance P, calcitonin gene-related peptide, and Leu- and Met-enkephalin, which profusely innervate Onuf's nucleus, are on the contrary not affected by the transection. They most likely originate from the cord itself or the dorsal root ganglia. Thus, Onuf's nucleus innervation in the baboon arises both from supraspinal and intraspinal sources. The present study provides an anatomical basis for both voluntary and reflex controls of excretory and sexual functions in a primate. The same neurotransmitter (serotonin) according to its cell origin and discrete topography could exert different influences upon the same effector system.

Animals↗