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L Sebastiani

Publications and source records attributed to L Sebastiani.

At least 37 records · Page 2Linked to original sources
PubMed1993

Purkinje cell responses in the anterior cerebellar vermis during Pavlovian fear conditioning in the rabbit.

Extracellular single-unit recordings of Purkinje cells in the anterior cerebellar vermis (ACV) of the rabbit found evidence of short-latency (20-30 ms) differential responses to discriminatively-conditioned auditory stimuli during Pavlovian fear conditioning procedures. These differential unit responses appeared to be a function of learning as differential ACV Purkinje cell responses were not observed in naive (untrained) animals. Some of these evoked neurophysiological responses were also correlated with the behavioral conditioned autonomic response. (CAR); a conditioned bradycardiac response. These electrophysiological data, coupled with previous lesion results, suggest that the ACV is part of an important neural circuit for Pavlovian conditioned bradycardia.

Acoustic Stimulation↗
PubMed1992

Influence of the cerebellar posterior vermis on the acquisition of the classically conditioned bradycardic response in the rabbit.

The magnitude of classically conditioned bradycardia was studied in rabbits in which various cerebellar regions (lobule IX or the posterior vermis or the hemispheres) had been removed surgically. Lesions were shown histologically to be restricted to the cortex and the underlying white matter without any damage to the deep cerebellar nuclei. In the conditioning procedure, tones were employed as conditioned stimuli (CS) and ear shocks as unconditioned stimuli (US). Cerebellar lesions did not affect the characteristics of the bradycardic orienting response, baseline heart rate or the unconditioned tachycardic response to US. The conditioned bradycardia was significantly reduced in magnitude with respect to controls in rabbits submitted to removal of posterior vermis, while it was unaffected in lobule IX and hemispheric lesioned rabbits. The temporal pattern of development and habituation of the bradycardiac response through the conditioning session, as well as its topography, did not differ from controls in any of the lesioned rabbits. After the first conditioning session, some control rabbits were submitted to removal of the posterior vermis and then conditioned again, following an identical procedure. Their pre- and post-lesion conditioned responses did not exhibit any appreciable differences and were similar to the responses exhibited by a group of unoperated controls which were submitted to a reconditioning session. It is concluded that in the rabbit the cerebellar posterior vermis is involved in the initial acquisition of the classically conditioned bradycardia, but it is not the site of its memory trace.

Animals↗
PubMed1991

[Prevalence of anti-Yersinia enterocolitica antibodies in an open population of the city of Rome].

This work shows the results of a seroepidemiological study of a group of 691 apparently healthy individuals: 246 males and 445 females from a Rome out-patient consulting center. 72 individuals (10.42%) were found positive with an antibody titer from 1:20 to 1:40. The percentages regarding the sexes and also those regarding the age groups did not show significant differences. The results of the research demonstrate a limited diffusion of Yersinia enterocolitica infection in the area under scrutiny. The results are correlated with those of similar researches.

Adolescent↗
PubMed1991

Efferent connections of lobule IX of the posterior cerebellar cortex in the rabbit--some functional considerations.

The Purkinje cell projection from the cardiovascular region of sublobule b of the uvula (medial area of zone A) has been investigated using anterograde tracing methods in the rabbit. The importance of the integrity of the identified pathways in mediating the cardiovascular responses from the uvula has been studied in subsequent lesioning experiments. Wheat germ agglutinin-conjugated horseradish peroxidase or tritiated amino acids were microinjected into sublobule IXb. This resulted in anterogradely labelled Purkinje cell axons in both the inferior and superior cerebellar peduncle. In agreement with previous studies in rabbit we also found labelled fibres at the level of the fastigial nucleus and vestibular complex. However, the labelled fibres we observed in the parabrachial nucleus have not been reported in previous studies except in the prosimian primate. Projections from IXb showed terminal-like patterns of label in the ventromedial region of the caudal fastigial nucleus, the dorsal areas of the superior and inferior vestibular nuclei and in the medial and lateral divisions of the parabrachial nucleus. Labelled fibres were also seen coursing in the lateral vestibular nucleus. Lesioning experiments have revealed that the integrity of the superior cerebellar peduncle is essential for the expression of the cardiovascular responses (bradycardia and depressor response) elicited from the uvula in the anaesthetized rabbit. In contrast, the pattern of cardiovascular response evoked in a decerebrate rabbit (tachycardia and pressor response) was abolished when the inferior cerebellar peduncle was lesioned.

Amino Acids↗
PubMed1990

Injections of 6-hydroxydopamine in the substantia nigra of the rat brain: morphological and biochemical effects.

Rats with unilateral injections of 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta were classified as active and inactive according to the intensity of their spontaneous and/or apomorphine-induced turning behavior (TB), and sacrificed at different survival times for morphological and biochemical analysis. In active rats, at any survival time, dopaminergic fluorescence in the nigrostriatal system as well as dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) content of the nucleus caudatus-putamen drastically decreased on the brain side ipsilateral to the injection. Dopaminergic fluorescence as well as DA and DOPAC content of the mesolimbic system ipsilateral to the injection also decreased. In inactive rats, at any survival time, 6-OHDA-induced lesions only partially involved both nigrostriatal and mesolimbic systems. Our results are indicative of a good correlation between the intensity of TB and the extent of 6-OHDA-induced lesions, as assessed by morphological and biochemical analysis.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Reorganization of visual pathways following posthatching removal of one retina in pigeons.

Organization of visual pathways was studied in 2-month-old pigeons that underwent unilateral retinal removal on either the day of hatching (ERA, i.e., early retinal ablated) or the 9th day after hatching (LRA, i.e., late retinal ablated). A general size reduction of visual areas contralateral to the removed retina was found in ERA pigeons, which additionally showed an altered differentiation of thalamic visual targets as well as a different cytoarchitectonic arrangement of the superficial layers of the optic tectum. No comparable modifications were found in LRA pigeons. The retinal projections of the remaining eye were studied following intraocular injections of 3H-proline. Both in ERA and LRA pigeons, the distribution of retinofugal afferents to primary visual regions contralateral to the injected eye was similar to that of control pigeons. Anomalous ipsilateral projections from the remaining retina to primary retinorecipient regions were found in ERA pigeons only. Effects of early ablation of one retina on second-order visual connections were also studied. Following injections of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) into the visual Wulst contralateral to the operated eye, a smaller number of ipsilateral projecting thalamo-Wulst neurons was found as compared with control pigeons. In contrast, the contralateral thalamo-Wulst projections were increased. No changes in thalamo-Wulst projections were found following tracer injections into the opposite Wulst, i.e., ipsilateral to the operated eye. The present study demonstrates a substantial anatomical reorganization of both primary and secondary visual pathways following unilateral retinal removal immediately after hatching, when maturation of the visual system is not yet completed.

Animals↗
PubMed1989

p-Chloroamphetamine treatment modifies evoked responses to sinusoidal gratings in the pigeon optic tectum.

This study was performed in order to establish whether selective depletion of serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the pigeon optic tectum (TeO) induced by p-chloroamphetamine (p-CA) modified tectal evoked potentials (TEPs). TEPs in response to sinusoidal gratings of different contrast, spatial and temporal frequency were recorded in control pigeons and in pigeons intraperitoneally injected with p-CA (10 mg/kg; two administrations in consecutive days). TEPs of p-CA treated pigeons, as compared to those of control pigeons, were reduced in amplitude as a function of contrast, spatial and temporal frequency. In addition, TEPs of p-CA treated pigeons differed from those recorded in controls in their transfer characteristics of contrast and spatial frequency. In particular, TEPs of p-CA treated pigeons did not saturate at moderate contrast, unlike those of controls. Furthermore, the TEP spatial tuning in p-CA treated pigeons is broader than that in controls; it thus suggests a reduction of spatial-frequency selectivity. These findings indicate that a selective neurotoxin for serotonergic systems, such as p-CA, can serve as a useful denervation tool for the study of the serotonergic function in the pigeon TeO. In addition, selective changes of TEP properties suggest the possibility that serotonergic afferents play a modulatory role on the receptive-field characteristics of tectal neurons.

Analysis of Variance↗
PubMed1989

High-dose etoposide and autologous bone marrow transplantation as intensification treatment in small cell lung cancer: a pilot study.

A pilot study was conducted in which 15 patients with small cell lung cancer (SCLC) with limited or extended disease were treated with high dose etoposide (600 mg/m2 daily for 3 consecutive days) followed by autologous bone marrow transplantation (ABMT). Twelve patients underwent a double graft. All had achieved complete or partial remission with conventional induction chemotherapy (adriamycin and etoposide, plus cisplatin in five cases). After ABMT six of the 15 patients did not receive radiotherapy to the chest; all but four patients received prophylactic brain irradiation. No toxic deaths were recorded during the period of aplasia. Eleven patients relapsed and died after ABMT. The median time to death was 18 months. One other patient died at 13 months of unknown cause. At the present time three patients are alive and free of disease at 54, 51 and 47 months respectively. This pilot study shows that high dose etoposide and ABMT is well tolerated as late intensification for responsive SCLC. Definite conclusions about its precise role in therapy cannot yet be drawn.

Adult↗
PubMed1987

Morphological and functional changes in the retinotectal system of the pigeon during the early posthatching period.

Anterograde transport of either HRP or wheat germ agglutinin-conjugated HRP was used to study the posthatching development of the retinotectal connection in the pigeon. The functional maturation of the retinotectal system was also investigated by recording electroretinographic (ERG) and tectal evoked (TEP) responses to either flash or pattern stimuli. Two main morphological changes occurred in the retinotectal system during the first 6 days after hatching: an ipsilateral retinofugal component that was present at hatching disappeared and the outer tectal layers were progressively invaded by the contralateral retinofugal axons, which at hatching were limited to the stratum griseum et fibrosum superficiale of the dorsolateral tectal quadrant. During the early posthatching period, at the same developmental stage at which an ERG to unpatterned or patterned stimulation could first be recorded, a visually evoked response could be elicited in the contralateral optic tectum. Therefore, the retina and optic tectum seem to start functioning simultaneously, the limiting factor being the late maturation of photosensitive lamellae in the outer segments of the developing photoreceptors. During the first 20 days posthatching, the retinotectal system undergoes extensive development as revealed by latency and amplitude changes of the visually evoked potentials. We suggest that the pigeon visual system serves as a useful model for studies concerning visual development and plasticity.

Age Factors↗
PubMed1987

Rapidly progressive periodontitis. Neutrophil chemotaxis inhibitory factors associated with the presence of Bacteroides gingivalis in crevicular fluid.

In the last few years several bacteriological and immunological studies have investigated the role of bacteria and immune defects in order to establish the etiopathogenesis of periodontal disease. With regard to the immune system, a defect in polymorphonuclear neutrophil (PMN) chemotaxis has been frequently reported in patients with rapidly progressive or juvenile periodontitis. The purpose of this study was to investigate in five patients with rapidly progressive periodontitis and normal chemotaxis of peripheral blood PMNs the presence of chemotaxis inhibitory activity in gingival fluid and to relate such activity to three types of bacteria, often involved in rapidly evolving periodontal lesions, that are able to inhibit in vitro PMN chemotaxis: Bacteroides gingivalis, Capnocytophaga sp., and Actinobacillus actinomycetemcomitans. We found strong inhibitory activity in three of these patients. This activity was consistently associated with the finding of B. gingivalis in gingival pockets. We cannot rule out, however, that other substances not of bacterial origin could be responsible for such inhibitory activity. The strict association with B. gingivalis, known to secrete blocking factors, is highly suggestive, although this data must be considered preliminary.

Actinobacillus↗
PubMed1981

[Immunogenic activity of hemocyanin from the hemolymph of Helix pomatia and Octopus vulgaris].

The immunogenic activity of Helix Pomatia Haemocyanin (HPH) and Octopus vulgaris Haemocyanin (OVH) has been tested in rabbits. Primary and secondary antibody response has been evaluated in sera by agar double immuno-diffusion test (Ouchterlony), counter immunoelectrophoresis and complement fixation. Bath haemocyanins proved highly antigenic: antibody titers rising up to 1/3.200 after the second antigenic challenge. The Ouchterlony test showed a partial identity between H.P.H. and O.V.H. No adverse effect was evident in injected animals.

Animals↗
PubMed1980

[Serological studies of the immunological condition versus rebulla virus in maternal and neonatal serum samples].

In 116 serum pairs sampled from the mother and the newborn at delivery, the antibody level against Rubeola virus has been assessed haemagglutination inhibition test. Thirty one per cent of the mothers resulted not protected, as the antibody titer was below 1/16. A situation akin to that described in the same percentage of not protected women was 29,45%. In 19% of the newborns the antibody level against the virus proved higher than the mother's one by at least two dilution factors. Research work is in progress to try the reason of this result, as a possible consequence of different Ig classes or aspecific inhibitors involved.

Adult↗
PubMed1979

[Preservation at -195 degrees C of trypsinized organs for primary cultures].

Trypsinized cells from rabbit kidney can be kept at -195, 8 degrees C indefinitely. When necessary, propagation in monolayer cultures is readily obtained as primary cultures, provided that some conditions be respected: 1) only glass culture flask must be used. Falcon plastic vessels do not allow cell attachment in this type of primary culture 2) the lag period is particularly long: it taken about 20 days before the beginning of cell multiplication 3) fetal calf serum is toxic for the cells in the 2nd and 3rd change of the culture medium, during the lag period.

Animals↗
PubMedDate not supplied

The action of steroid hormones on peripheral myelin proteins: a possible new tool for the rebuilding of myelin?

The present paper summarizes recent results we have obtained while studying the effect of sex steroids on the gene expression of two peripheral myelin proteins, the glycoprotein Po (Po) and the peripheral myelin protein 22 (PMP22). In particular, we have analyzed the effect of progesterone (P), testosterone (T) and their 5alpha- and 3alpha-5alpha-reduced derivatives [respectively, dihydrotestosterone (DHTT) and 5alpha-androstan-3alpha, 17beta-diol (3alpha-diol) for T, and dihydroprogesterone (DHP) and tetrahydroprogesterone (THP) for P]. The data obtained, utilizing different in vivo and in vitro experimental models, have indicated that: a) DHP is able to enhance the low messenger levels of Po present in the sciatic nerve of aged male rats; b) P, DHP and THP treatments stimulate the gene expression of Po in the sciatic nerve of adult male rats or in cultures of rat Schwann cells, while only THP is effective on PMP22; c) P and DHP are also able to increase the low messenger levels of Po present in transected sciatic nerve; d) the removal of circulating androgens by castration is able to decrease the mRNA levels of Po in the sciatic nerve, a phenomenon which is counteracted by the consequent treatment with DHT; e) the stimulatory effect of DHT on the gene expression of Po is also evident in cultures of rat Schwann cells, but in this case the effect seems to be due to the interaction of this steroid with the progesterone receptor; f) in cultures of Schwann cells PMP22 mRNA levels are stimulated only by 3alpha-diol treatment. Taken together, these observations showing the positive effects of sex steroid hormones on the gene expressions of Po and PMP22, suggest that a treatment with these molecules or their synthetic agonists may be useful in cases in which the rebuilding of myelin is necessary.

Animals↗