Theta-like activity in hippocampal formation slices: the effect of strong disinhibition of GABAA and GABAB receptors

The involvement of GABAA and GABAB receptors in neural mechanisms responsible for the production of theta rhythms in hippocampal formation (HPC) slices is addressed in the present study. In a number of papers published in the last decade, we have demonstrated that theta-like activity can be successfully recorded in the limbic cortex maintained in vitro when the cholinergic agonists, acetylcholine, carbachol or muscarine, were added to the bath. Recently, we have also shown a strong GABAA modulation of the cholinergic-induced in vitro theta-like activity. This study presents a report of the first demonstration of in vitro theta-like field responses induced a consequence of simultaneously inhibiting hippocampal GABAA and GABAB receptors. HPC slices (350 microns) were maintained in a gas-liquid interface chamber (35 degrees C). Theta-like activity was induced in the presence of bath perfusion of bicuculline (GABAA antagonist) and 2-hydroxysaclophen (GABAB antagonist). This in vitro induced field response was antagonized both by muscimol (GABAA agonist) and baclophen (GABAB agonist). In addition, the experiments presented here revealed that bicuculline/2-hydroxysaclophen-induced in vitro theta-like activity also had a strong cholinergic M1 involvement: it was abolished by hemicholinium-3 (choline transport blocker) and pirenzepine (specific antagonist of M1 receptor), but not by gallamine (specific antagonist of M2 receptor). The results of the present study provided further evidence for a strong GABAergic/cholinergic interaction in the neural mechanism responsible for production of theta-like activity in the hippocampal formation slices.

The spontaneous theta rhythm recorded from the hypothalamus posterior in the cat in vivo

Rhythmical slow activity (theta) was mapped in the hypothalamic region in freely moving cats. We recorded well synchronized and high amplitude theta rhythm in the medial part of the hypothalamus posterior area. The EEG recordings made from lateral part of this hypothalamic region contained only irregular activity. These findings support earlier observations concerning the topography of hippocampal formation desynchrony and synchrony system. The observations of the present study also suggest that the hypothalamus posterior area is actively involved in the mechanisms responsible for generating theta oscillations in the cat.

The rhythmic slow activity recorded from entorhinal cortex in freely moving cats

The relationships between the entorhinal cortex (EC) and the hippocampal formation (Hipp) field potentials were examined in the present study. The detailed analyses of the signal let us group the patterns of theta appearance into three categories: (1) Theta rhythm dominating in both recordings from the EC and from the Hipp (2) Theta rhythm dominating in the Hipp with irregular activity in the EC (3) Theta rhythm dominating in the EC with irregular activity in the Hipp. These findings provide the evidence for the intrinsic generator of theta rhythm to be localized in entorhinal cortex in cats.

Muscarinic (M1) mediation of carbachol-induced theta in the cat entorhinal cortex in vitro

Entorhinal cortex slice preparations obtained from the cat exhibited theta rhythm during perfusion with 50 microM carbachol. The effect of carbachol was antagonized by the muscarinic blocker atropine sulphate, but not by hexamethonium and mecamylamine, which are antagonists of the nicotinic receptor. Further analysis of the pharmacological profile of these carbachol-induced theta oscillations showed that M1 receptor subtype to be involved in mediation of this EEG activity: the theta rhythm was antagonized by the M1 receptor blocker pirenzepine, but was unaffected by gallamine, an antagonist of the M2 receptor subtype.

Sympathetic skin response in scleroderma

Examination of the sympathetic skin response (SSR) was performed in 32 patients with systemic sclerosis, morphea and mixed connective tissue disease displaying scleroderma-like features. The control group consisted of 26 healthy subjects and 12 patients with other skin diseases and asymmetrical cutaneous changes. Right and left median and tibial nerves were stimulated successively and the responses were recorded from the palms and soles simultaneously. SSR abnormalities (delayed latency, decrease and/or asymmetry of amplitude, absent response) were observed in 68.8% of the patients, most frequently in linear scleroderma. An amplitude asymmetry of the responses from upper extremities was the most characteristic pattern of abnormalities. There was no correlation between the SSR and the localization, degree and character (inclurated oedema, atrophy, sclerosis) of skin changes, the duration of the disease, symptoms of the disorder of the autonomic nervous system symptoms (vasomotor and/or sudomotor) and the changes in capillaroscopy. All patients with slow motor conduction and sensor conduction velocities (MCV and SCV) had lower SSR amplitude and the patients with prolonged skin sensory chronaxy had more often delayed latency. The results revealed presence of disturbances of the autonomic nervous system in all varieties of scleroderma, both systemic and localized forms, even without any other signs of autonomic dysfunction.

Childhood scleromyositis: an overlap syndrome associated with PM-Scl antibody

Fourteen patients with childhood scleromyositis followed from 1 to more than 10 years experienced concomitant sclerodermoid and dermatomyositis features, variably expressed at one time or another during the course of the disease. The most characteristic features were myalgia-myositis, arthralgia-arthritis, puffy, atrophic, sclerotic fingers, and Raynaud's phenomenon. This overlap syndrome was the most frequent sclerodermoid condition in children, differing from both systemic scleroderma and dermatomyositis. The course of the disease was protracted and rather benign, and PM-Scl antibody was an important diagnostic and prognostic marker. We present criteria for diagnosis of scleromyositis and its differentiation from systemic scleroderma, dermatomyositis, and Sharp overlap syndrome.

Immunologic markers of systemic scleroderma in children

This study was performed on seven children with systemic scleroderma, three with the diffuse and four with the limited type. All three patients with diffuse scleroderma had high titers of clumpy pattern antinucleolar antibody on HEp-2 cells. The course of the disease was severe, and two children died. Four children with limited scleroderma had mild disease, and Scl-70 antibody, an immunologic marker that in adults is associated mostly with diffuse scleroderma. In one child Scl-70 antibody and anticentromere antibody coexisted, although previously the two were believed to be mutually exclusive. This study shows that limited scleroderma of childhood with slight cutaneous involvement may be associated with the Scl-70 marker. The findings in 10 adults in whom Raynaud's phenomenon developed in childhood and indurations appeared some years later, point to the significance of careful observation of these children, with repeated testing for immunologic markers of SSc. An important new finding is the association of different types of systemic sclerodermas with specific immunologic markers.

Autoantibodies to nucleolar antigens in systemic scleroderma: clinical correlations

Indirect immunofluorescence(IIF) and double immunodiffusion (DID) were performed on the sera of 64 patients who had a nucleolar immunofluorescence pattern on HEp-2 cells. Forty-nine of the sera were from 296 patients with systemic scleroderma (SSc) and 15 sera were from 214 patients with systemic lupus erythematosus (SLE). A homogeneous nucleolar staining pattern was found in 45 of the 64 sera (70.3%), a clumpy fluorescence associated with fibrillarin antibody in 14 (21.8%) and a speckled pattern was found in five of the sera (7.8%). There was a clear correlation between the sera which showed a homogeneous nucleolar staining pattern with symptoms of the polymyositis/scleroderma overlap syndrome that differed from SSc with concomitant myositis. The clumpy pattern was mainly associated with diffuse scleroderma and the speckled pattern with limited scleroderma (previously called acrosclerosis).

[Diagnostic value of the lupus band test in patients treated by chronic hemodialysis]

The diagnosis of systemic lupus erythematosus in cases with advanced renal failure is a serious clinical problem. The purpose of the study was an analysis of the incidence of various non-renal criteria (according to ARA) for the diagnosis of SLE in patients with chronic renal failure of various aetiology and find out whether the lupus band test in these patients may serve as an additional criterion for the diagnosis of SLE. The studied group comprised 39 patients with chronic renal failure (28 men and 13 women) aged 17-58 years. In this group 29 cases were treated with dialyses and 10 conservatively. The most frequent clinical sign (apart from renal changes) accepted as diagnostic criteria for the SLE was polyserositis and leucopenia and thrombocytopenia. In no case antinuclear antibodies, antibodies against DNA and against soluble nuclear antigens were found. Positive LBT was obtained in 72.4% of cases with chronic renal failure, particularly frequently in the dialysed patients. A positive result of the LBT cannot be of decisive importance in the diagnosis of SLE but may suggest a need of more detailed investigations (determination of Ro antibodies) for confirmation of the diagnosis.

[Studies of the role of cellular immunity and angiogenetic changes in the pathogenesis of circumscribed scleroderma]

The studies were performed in 48 patients with morphea and included evaluation of 1) antinuclear antibodies 2) lymphocyte induced angiogenesis 3) natural killer (NK) cell activity and 4) T cell subpopulations in peripheral blood. The presence of antinuclear antibodies was found in 44.4% (8/18) patients with scleroderma linearis and in 21% (4/19) patients with morphea disseminata. Lymphocyte induced angiogenesis was increased in 41.5% (17/41) morphea patients, mainly in cases with pronounced vascular changes. The E rosette forming test showed a decreased percentage of active rosette forming cells (ARFC) and total rosette forming cells (TRFC) in peripheral blood and the NK cell activity was lowered in patients with morphea. These results obtained in patients with morphea show some similarities and differences in comparison to cellular immunity disturbances in patients with systemic scleroderma.

[Studies of the mechanism of disorders of the natural killer cell activity in patients with systemic scleroderma]

The NK activity of peripheral blood mononuclear cells (PBMC) was evaluated in 90 patients with various subsets of systemic scleroderma (SSc). The NK activity, as performed with K-562 as target cell, was found to be significantly lowered in patients with diffuse scleroderma, but did not differ from the healthy control in patients with acrosclerosis. The lowest values in the NK activity assay were obtained in patients with most extensive skin involvement and severe internal organ changes. The NK activity of healthy donors' PBMC was significantly decreased by addition of SSc patients PBMC (50:1) to the cytotoxicity assay, but was not influenced by the patients sera.

Cytotoxic effects of sera from patients with systemic scleroderma: comparison of three different in vitro methods

Sera from 93 patients with systemic scleroderma including incipient or prodromal acroscleroderma and from 43 healthy individuals were studied for cytotoxic effects on endothelial cells by means of three different in vitro methods. Inhibition of 3H-thymidine incorporation by endothelium was caused by about 33% of sera, almost exclusively from patients with diffuse scleroderma and the transitional form: acroscleroderma--diffuse scleroderma. An antibody-dependent cellular cytotoxicity assay revealed cytotoxicity of about 37% of sera from patients with diffuse scleroderma and the transitional form but also of a proportion of sera from patients with CREST syndrome with pronounced vascular changes. Serum cytotoxic activity, revealed by both methods, was related with more frequent involvement of muscle and kidney in the patients. A direct 51Cr release assay showed the cytotoxicity only in 4 of 68 cases in diffuse scleroderma with pronounced internal organ involvement. Thus, depending on the method used, various types of cytotoxicity could be detected in sera from patients with systemic scleroderma.

Are ACA and Scl 70 antibodies mutually exclusive?

Serological studies using indirect immunofluorescence, double immunodiffusion and immunoblot with recombinant Topo I and kinetochore antigens were performed in 180 patients with systemic scleroderma. In the sera of 10 patients, we found coexisting ACA and Scl 70 antibodies, and this was confirmed by all three methods. The relationship between the coexistence of these antibodies and the clinical features of the disease is not clear, although in all these cases there was pronounced vascular involvement.

Phototests in patients with various forms of lupus erythematosus

Responses to ultraviolet B (UVB; 290-320 nm) were tested in 227 patients with main forms of lupus erythematosus (LE): discoid LE (DLE), discoid disseminated LE (DDLE), systemic LE (SLE), and subacute cutaneous LE (SCLE). Four parameters were evaluated: minimal erythema dose (MED), its distribution, persistence of erythema, and photoreproduction of lesions. Patients with LE differed considerably from controls in their UVB reactivity. In addition, there were significant differences between various LE forms, even after a single UV exposure. Lowered MED in comparison to controls was observed most frequently in SLE patients (64.4%) and least frequently in DLE patients (32.1%). Prolonged persistence of erythema induced by 1-2 MED was a constant finding in SCLE. In SLE and DDLE, it was observed in more than 80% of patients, and in DLE in 56.7% of examined cases. Photoreproduction of lesions after single UVB exposure was observed most frequently in SCLE (62.5%) and only in 10% of DLE patients.

Theophylline-resistant and theophylline-sensitive "active" and "total" E rosette-forming lymphocytes in patients with systemic scleroderma

Using the E rosette test and its modification with theophylline, we have studied T regulatory lymphocytes in various forms of systemic scleroderma. Mean percentages of active rosette-forming cells (ARFC) as well as the fraction resistant to theophylline incubation (ARFC-res) were significantly decreased, irrespective of the variety of the disease, compared to the age-matched controls. Late ("cold") rosette-forming fractions were unimpaired. The theophylline-sensitive fraction of total rosette-forming cells (TRFC-sens), which contains mainly cells from the suppressor circuit, was found to be lowered in all patients groups studied, whereas the ARFC-sens fraction was significantly decreased only in patients with diffuse scleroderma over 50 years of age, in whom there was a tendency to a more severe course, as manifested by pronounced systemic organ involvement. The lowered values of E rosette tests were found in a majority of SSc patients and were correlated with the appearance in the sera of factors capable of inhibiting ARFC formation by normal human peripheral blood T lymphocytes. Normal values of the E rosette test were related to the presence in the patients' sera of factors stimulating ARFC formation by normal lymphocytes. We surmise from the results that in SSc patients the T-cell defect is not only restricted to T suppressor cells but also refers to the active theophylline-resistant fraction containing mainly T inducer and T cytotoxic cells.

Natural killer cell activity of peripheral blood mononuclear cells from patients with various forms of lupus erythematosus

Natural killer (NK) cell activity of peripheral blood mononuclear cells from 28 patients with cutaneous discoid lupus erythematosus, seven with subacute cutaneous lupus erythematosus, and 17 with systemic lupus erythematosus was studied using a 4 h 51Cr release assay using K-562 cells as target cells. NK cell activity was found to be markedly decreased not only in patients with systemic lupus erythematosus but also in a proportion of cases of subacute cutaneous lupus erythematosus and cutaneous discoid lupus erythematosus (57% and 39% respectively). There was a relationship between the activity and severity of LE and the decrease in NK cell activity.