Magnetophotoluminescence of Modulation-Doped CdTe Multiple Quantum Wells

Modulation-doped CdTe quantum wells (QWs) with Cd0.7Mg0.3Te barriers were studied by photoluminescence (PL) and far-infrared Fourier spectroscopy under a magnetic field at 4.2 K and by Raman spectroscopy at room temperature. Two samples were tested: a sample which contained ten QWs (MQW) and a sample with one QW (SQW). The width of each QW was equal to 20 nm, and each of them was modulation-doped with iodine donors introduced in a 4 nm thick layer. The concentration of donors in each doped layer was nominally identical, but the thickness of the spacer in SQW and MQW samples was 20 and 10 nm, respectively. This resulted in a two times higher electron concentration per well in the MQW sample than in the SQW sample. We observed differences in PL from the two samples: the energy range of PL was different, and one observed phonon replicas in MQW which were absent in the SQW sample. An analysis of oscillations of the PL intensity as a function of magnetic field indicated that PL resulted from the recombination of free electrons in the conduction band with free or localized holes in the case of SQW and MQW samples, respectively.

Treatment of intrabony defects with modified perforated membranes in aggressive periodontitis: a 4-year follow-up of a randomized controlled trial

OBJECTIVE

(1) To assess long-term outcomes 4 years following guided tissue regeneration (GTR) of intrabony defects in patients diagnosed with aggressive periodontitis (AgP) and (2) to identify predictors of clinical attachment level (CAL) gain and bone/graft density gain.

MATERIALS AND METHODS

In 15 patients, two deep intrabony defects were randomly treated with xenogenic graft plus modified perforated membranes (MPM, tests) or xenogenic graft plus standard collagen membranes (CM, controls). After 4 years, clinical and radiographic outcomes were evaluated and compared with outcomes at baseline and after 1 year.

RESULTS

After 4 years, 14 test sites and 13 control sites were available for analysis. One tooth was lost as a result of root fracture. There were significant improvements in all evaluated parameters after 1 and 4 years in relation to baseline, but no differences were observed between tests and controls. However, some non-significant changes were found between 1 and 4 years. Regression analyses showed that recurrence of periodontitis was a significant predictor for CAL gain (p = 0.001) and bone/graft density gain (p = 0.024) from 1 to 4 years.

CONCLUSIONS

GTR of intrabony defects in AgP with either standard or modified CM yielded similarly successful and maintainable clinical benefits for compromised teeth 4 years following the surgery. The use of MPM showed no additional benefit.

CLINICAL RELEVANCE

This study demonstrates that most of the positive outcomes of GTR in AgP may be preserved over 4 years. Periodontitis recurrence might influence long-term outcomes.

Neurodegeneration and inflammation in hippocampus in experimental autoimmune encephalomyelitis induced in rats by one--time administration of encephalitogenic T cells

Cognitive dysfunction is relatively frequent in multiple sclerosis (MS) and it happens from the early stages of the disease. There is increasing evidence that the grey matter may be involved in autoimmune inflammation during relapses of MS. The purpose of this study was to evaluate if a single transfer of encephalitogenic T cells, mimicking a relapse of MS, may cause hippocampal damage and memory disturbances in rats. Lewis rats were injected with anti-MBP CD4+ T cells, that induced one-phase autoimmune encephalomyelitis (EAE) with full recovery from motor impairments at 10-15 days. The spatial learning and memory were tested by the Morris water maze test in control and EAE animals, 30 and 90 days post-induction (dpi). The neural injury and inflammation was investigated in the hippocampus by immunohistochemistry and quantitative analyses. There was a marked decrease in the number of CA1 and CA4 pyramidal neurons 5 dpi. The loss of neurons then aggravated till the 90 dpi. An increase in microglial and astroglial activation and in pro-inflammatory cytokines mRNA expression in the hippocampus, were present 30 and 90 dpi. Nerve growth factor and brain-derived neurotrophic factor mRNA levels were also significantly elevated. The water maze test, however, did not reveal memory deficits. The present data indicate that a single transfer of autoimmune T cells results in preserved inflammation and probable on-going neuronal injury in the hippocampus, long after recovery from motor disturbances. These findings suggest that any relapse of the MS may start the neurodegenerative process in the hippocampus, which is not necessarily connected with memory deficits.

NG2 positive cells of rat spinal cord activated during experimental autoimmune encephalomyelitis are spatially associated with radially oriented astroglia and express p75 receptor: a role for nerve growth factor in oligodendrocyte progenitor migration?

Data have been provided from several studies that support the proposal that the adult oligodendrocyte progenitors migrate into the lesioned areas under conditions of experimental autoimmune encephalomyelitis (EAE). However, the routes of migration of these cells and the governing mechanisms are not clear. In the present studies, we have examined the effect of EAE upon activation of endogenous oligodendroglia progenitors and their spatial distribution in the spinal cord of Lewis rats using immunocytochemical procedures. Antibodies against the marker chondroitin sulfate proteoglycan NG2, are used for identification of oligodendroglia progenitors. We find that the activated elongated subpopulation of NG2 positive oligodendroglia progenitors of white matter is spatially associated with the radially-oriented astroglia during the acute phase of EAE. The latter re-expressed the phenotypic embryonic marker nestin while still expressing the mature astroglial marker GFAP. The elongated oligodendroglia progenitors express p75 receptor. In addition, colocalization of NG2 and p75 is observed also in ependymal neural cells of the central canal and the subventricular zone. This raises the possibility that the activated NG2+/p75+ parenchymal cell pool may also be recruited from multipotent neural cells of the germination areas. Our data suggest that, under EAE conditions, the radially oriented astroglia of juvenile phenotype may serve as scaffolding for migrating activated endogenous oligodendroglia progenitors just like radial glia provide a path for neuronal and oligodendroglia progenitor cells in embryonic stage. The expression of p75 receptor in oligodendroglia progenitors associated with radially oriented astroglia during EAE may implicate a role for NGF in the regulation of migration of oligodendroglia progenitors.

Evaluation of the Incidence of Periodontitis-Associated Bacteria in the Atherosclerotic Plaque of Coronary Blood Vessels

BACKGROUND

Unstable atherosclerotic plaque is a dangerous clinical condition, possibly leading to acute coronary deficiency resulting in cardiac infarction. Questions about the role of inflammatory factors in the formation of pathological lesions in the endothelium of coronary vessels have often been raised. This condition may be caused by bacteria that are able to initiate clot formation in a blood vessel, destabilizing an atherosclerotic plaque that is already present. The sources of these pathogens are chronic inflammatory processes occurring in the host, including periodontal disease, which is one of the most frequent conditions. The aim of this study was to evaluate the incidence of selected anaerobic bacteria in subgingival and atherosclerotic plaque in patients treated surgically because of coronary vessel obliteration.

METHODS

The study was performed on 20 individuals with chronic periodontitis. Subgingival plaque was collected from periodontal pockets >5 mm. DNA testing was used to identify eight pathogens responsible for periodontal tissue destruction. Material from atherosclerotic plaques was collected from the same patients during bypass surgery, and DNA testing by the same method was performed.

RESULTS

In 13 of 20 patients, the pathogens most frequently found in severe chronic periodontitis were also found in coronary vessels. In 10 cases, those species of bacteria were also present in atherosclerotic plaque. The most frequently identified bacteria were Porphyromonas gingivalis and Treponema denticola.

CONCLUSIONS

In patients with the severe form of chronic periodontitis, it seems that clinical attachment loss is not associated with bacterial permeability into coronary vessels. What is important is the presence of an active inflammatory process expressed by a significantly higher bleeding index in those patients in whom the examined bacterial species were found in atherosclerotic plaque.

Periodontitis as a risk factor of coronary heart diseases?

BACKGROUND

Unstable atherosclerotic plaque is a dangerous clinical state, possibly leading to acute coronary deficiency resulting in cardiac infarction. Inflammatory factor's role in creating pathological lesions in the endothelium of coronary vessels is frequently raised. This state may be caused by bacteria able to initiate clot formation in blood vessel and destabilizing atherosclerotic plaque already present. Source of these pathogens are chronic inflammatory processes occurring in organism, among them periodontal disease as one of more frequent. Aim of the work was to evaluate incidence of selected anaerobic bacteria in subgingival plaque and in atherosclerotic plaque in patients treated surgically because of coronary vessels' obliteration.

METHODS

Study was performed on 20 individuals with chronic periodontitis. Subgingival plaque was collected from periodontal pockets deeper than 5 mm DNA test was used for marking eight pathogens responsible for periodontal tissues destruction. In the same patients, as well as in 10 edentulous individuals material from atherosclerotic plaque was collected during by-pass implantation procedure, and identical DNA testing occurred.

RESULTS

In 13 of 20 patients pathogens most frequent in severe chronic periodontitis were found in coronary vessels. In 10 cases those bacteria were also present in atherosclerotic plaque. Pathogens linked with periodontal disease were also found in 7 of 10 edentulous individuals. Most frequently marked bacteria were: Porphyromonas gingivalis and Treponema denticola.

CONCLUSIONS

It seems that advancement of periodontal disease does not have influence on bacteria permeability to coronary vessels. Important is the presence of active inflammatory process expressed by significantly higher bleeding index in patients with marked bacteria in atherosclerotic plaque.

Quantitative morphological study of microglial cells in the ischemic rat brain using principal component analysis

Pathogenic stimuli induce alterations in the morphology of microglial cells. We analysed changes in lectin-stained cells on the 1st, 3rd, 7th or 14th day after transient global ischemia. Three areas differing in the degree of microglial reaction were selected for analysis: the upper cerebral cortex, the hippocampal CA1 area, and the hilus of the dentate gyrus. Nine morphological parameters, including fractal dimension, lacunarity, self-similarity range, solidity, convexity and form factor were determined. Then the resultant data were processed using principal component analysis (PCA). We found that the two first principal components together explained more than 73% of the observed variability, and may be sufficient both to describe the morphological diversity of the cells, and to determine the dynamics and direction of the changes. In both hippocampal areas, the transformation to hypertrophied and phagocytic cells was observed, but changes in the hilus were faster than in the CA1. In contrast, in the cortex, a microglial reaction was characterised by an increase in the complexity of processes. The results presented show that the quantitative morphological analysis can be an effective tool in research on the reactive behaviour of microglia and, particularly, in the detection of small and early changes in the cells.

Conversion of the Tetrameric Restriction Endonuclease Bse634I into a Dimer: Oligomeric Structure–Stability–Function Correlations

The Bse634I restriction endonuclease is a tetramer and belongs to the type IIF subtype of restriction enzymes. It requires two recognition sites for its optimal activity and cleaves plasmid DNA with two sites much faster than a single-site DNA. We show that disruption of the tetramerisation interface of Bse634I by site-directed mutagenesis converts the tetrameric enzyme into a dimer. Dimeric W228A mutant cleaves plasmid DNA containing one or two sites with the same efficiency as the tetramer cleaves the two-site plasmid. Hence, the catalytic activity of the Bse634I tetramer on a single-site DNA is down-regulated due to the cross-talking interactions between the individual dimers. The autoinhibition within the Bse634I tetramer is relieved by bridging two DNA copies into the synaptic complex that promotes fast and concerted cleavage at both sites. Cleavage analysis of the oligonucleotide attached to the solid support revealed that Bse634I is able to form catalytically competent synaptic complexes by bridging two molecules of the cognate DNA, cognate DNA-miscognate DNA and cognate DNA-product DNA. Taken together, our data demonstrate that a single W228A mutation converts a tetrameric type IIF restriction enzyme Bse634I into the orthodox dimeric type IIP restriction endonuclease. However, the stability of the dimer towards chemical denaturants, thermal inactivation and proteolytic degradation are compromised.

Concomitant up-regulation of astroglial high and low affinity nerve growth factor receptors in the CA1 hippocampal area following global transient cerebral ischemia in rat

We have examined the effect of global transient cerebral ischemia, evoked in rat by 10 min of cardiac arrest, upon the changes in the cellular expression of two nerve growth factor (NGF) receptors (TrkA and p75) in the hippocampus. We have used immunocytochemical procedures, including a quantitative analysis of staining, along with some quantitative morphological analyses. We have found, under ischemic conditions, a decrease of TrkA immunoreactivity in degenerating CA1 pyramidal neurons and in neuropil. On the other hand, a strong, ischemia-induced up-regulation of TrkA and p75 immunoreactivity was observed in the majority of reactive astroglia population in the adjacent CA1 hippocampal region. The colocalization of the two receptors in the same reactive astroglial cells was evidenced by double immunostaining and further supported by quantitative morphological analysis of TrkA and p75 immunoreactive glial cells. Our data implicate the involvement of NGF receptors in the postischemic regulation of astrocytic function; however, the lack of NGF receptor expression on some astrocytes suggests heterogeneity of astroglia population. Our results also indicate that the lack of neuroprotective action of astroglial NGF induced in the ischemic hippocampus [J Neurosci Res 41 (1995) 684; Acta Neurobiol Exp 57 (1997) 31; Neuroscience 91 (1999) 1027] is not caused by a paucity of NGF receptors but may rather be due to the counteraction of some proinflammatory substances, released simultaneously by glia cells. On the other hand, the up-regulated astroglial TrkA receptor may be an important target for exogenous NGF, which, as previously described [J Neurosci 11 (1991) 2914; Neurosci Lett 141 (1992) 161], exerts a neuroprotective effect in ischemia.

Morphological transformations of cells immunopositive for GFAP, TrkA or p75 in the CA1 hippocampal area following transient global ischemia in the rat. A quantitative study

Transient global ischemia induces intensive neuronal degeneration in the hippocampal CA1 pyramidal layer, accompanied by reactive transformation of glial cells. Previously, we have shown using the double immunostaining method that the NGF receptors (NGFR) p75 and TrkA are expressed mainly on subpopulations of GFAP+ astrocytes, and this expression increases progressively after ischemia. In the presented study, we analyzed quantitatively the morphological transformations of cells immunopositive for GFAP or NGF receptors in the stratum radiatum of the CA1 hippocampal area in different survival periods after ischemia, evoked by 10-min cardiac arrest in adult rats. In control brains, NGF receptors were expressed only on small cells with poorly ramified processes. After ischemia, the NGFR+ cells increased in size and morphological complexity (measured using fractal analysis). However, even 2 weeks after ischemia these cells did not reach the size and value of the fractal dimension typical of the largest GFAP+ astrocytes. Moreover, the reaction of NGFR+ cells was significantly delayed in comparison with the total astrocyte population. The obtained results suggest that NGF receptors are expressed mainly by immature astrocytes and ischemia induces the maturation of these cells.

High-affinity NGF receptor in the rat spinal cord during acute and chronic phases of experimental autoimmune encephalomyelitis: a possible functional significance

The biological effects of Nerve Growth Factor (NGF) are primarily mediated via its high affinity receptor-TrkA. In the present study, we examined the effect of experimental autoimmune encephalomyelitis (EAE) upon the expression of TrkA in neuronal and non-neuronal cells of the spinal cord of Lewis rats during the acute (14 days postimmunization) and chronic (12 months postimmunization) phases of the disease. In the normal spinal cord, both of mature and aged rats, we found TrkA immunoreaction (TrkA-IR) in the motoneurons of the Rexed lamina IX and in both oligo- and astroglia cells. In the acute phase of the disease, we found a reduction of TrkA immunoreactivity in motoneurons and its up-regulation in oligodendroglia, mainly in the white matter. We also confirmed our previous findings concerning the up-regulation of TrkA-IR in astroglia. Both neuronal and non-neuronal changes of TrkA immunoreactivity had a transient character: they were not seen in the chronic phase of the disease. Our results suggest that both neuronal and glial TrkA expression changes depend on inflammation. Moreover, our data indicate that, during the acute phase of EAE, the glial cells become more receptive to NGF, pointing to glia as an important target for pharmacological manipulations, particularly for exogenously administered NGF.

Dentate granule neuron apoptosis and glia activation in murine hippocampus induced by trimethyltin exposure

We investigated the effect of trimethyltin (TMT), a well-known neurotoxicant, on murine hippocampal neurons and glial cells. Three days following intraperitoneal (i.p.) injection of TMT into 1-month-old Balb/c mice at a dose of 2.5 mg/kg body weight we detected damage of the dentate gyrus granular neurons. The dying cells displayed chromatin condensation and internucleosomal DNA fragmentation, which are the most characteristic features of apoptosis. To study, if prolyl oligopeptidase is engaged in neuronal apoptosis following TMT administration, we pretreated mice with the specific inhibitor--Fmoc-Pro-ProCN in doses of 5 and 10 mg/kg body weight (i.p. injection). Three days following injection we did not observe any attenuation of neurotoxic damage, regardless of inhibitor dose, indicating the lack of prolyl oligopeptidase contribution to neuronal injury caused by TMT. The neurodegeneration was associated with reactive astrogliosis in whole hippocampus, but particularly in injured dentate gyrus. The reactive astrocytes showed an increased nerve growth factor (NGF) expression in ventral as well as dorsal hippocampal parts. NGF immunoreactivity was also augmented in neurons of CA3/CA4 areas, which were almost totally spared after TMT intoxication. It suggested a role for this neurotrophin in protection of pyramidal cells from loss of connection between CA3/CA4 and dentate gyrus fields. The granule neurons' death was accompanied by increased histochemical staining with isolectin B4, a marker of microglia, in the region of neurodegeneration. The microglial cells displayed ramified and ameboid morphology, characteristic of their reactive forms. Activated microglia were the main source of interleukin 1beta (IL-1beta). It is possible that this cytokine may participate in neurodegeneration of granule cells. Alternatively, IL-1beta elaborated by microglia could play a role in increasing NGF expression, both in astroglia and in CA3/CA4 neurons.

The upregulation of nerve growth factor receptors in reactive astrocytes of rat spinal cord during experimental autoimmune encephalomyelitis

Using immunocytochemistry, we have examined the effect of experimental autoimmune encephalomyelitis (EAE) upon the expression of nerve growth factor (NGF) and its TrkA and p75 receptors in astroglia cells of the spinal cord of Lewis rats. We have found that, in normal spinal cord, astroglia of white matter expressed both NGF receptors while those in gray matter expressed only TrkA and no astroglia expressed NGF. During EAE, strong upregulation of TrkA in the astroglia of gray and white matter was found, particularly in a population of radially oriented astrocytes. An upregulation of p75 was noted in radial astroglia and, to some extent, also in the stellate astrocytes of white matter. In general, the upregulation of NGF receptor immunoreactivities in astroglia correlated with the strong intensification of glial fibrillary acidic protein immunocytochemistry, a prominent feature of EAE. No NGF immunoreactivity appeared in any astroglia cells during EAE. Our results suggest that, during EAE, astroglia of the spinal cord become particularly receptive to NGF, possibly as part of a mechanism enabling astroglial cells to respond to localized release of neurotrophins. Moreover, our data suggest that spinal cord astroglia cells may be a potential target for pharmacological manipulations in EAE.

Interleukin 6, tumor necrosis factor alpha and their soluble receptors in the blood serum of patients with denture stomatitis and fungal infection

Determinations of the blood serum levels of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and their soluble receptors (sIL-6R, sTNFR) in denture stomatitis patients (DS) were performed. Serum levels of interleukins and their soluble receptors were measured using the ELISA method. In all examined patients mycological diagnostics were conducted using API 20C AUX stripe tests and an automatic ATB machine. Results were compared with those of healthy denture wearers (D), and controls (C). In DS patients, yeasts were isolated in 90.9%, in D in 66.7% of cases. The most often isolated species in both groups was Candida albicans. Mean concentrations of IL-6 and TNF-alpha were statistically significantly higher in DS and D groups compared to controls. Mean concentrations of sIL-6R were similar in all groups; however, concentrations of sTNFR in both DS and D groups were significantly lower compared to controls. There were no correlations found between values of IL-6 and TNF-alpha nor between examined interleukins and their soluble receptors.

Prolonged and concomitant induction of astroglial immunoreactivity of interleukin-1beta and interleukin-6 in the rat hippocampus after transient global ischemia

We have investigated the pattern of expression of IL-1beta and IL-6 immunoreactivities in rat hippocampus after transient complete brain ischemia evoked by a 10 min cardiac arrest, at survival times ranging from 1 day to 28 days. To identify the cell types expressing the two immunoreactivities we used specific cell markers and combined staining procedures. In the intact brain IL-1beta and IL-6 were mainly localized in neurons particularly in pyramidal and granular cell layers. Ischemic insult resulted in a concomitant induction of IL-1beta and IL-6 immunoreactivities in multiple astroglia especially in the CA1 area which is the most vulnerable to ischemic insult as manifested by a massive delayed neuronal death accompanied by an intense gliosis. The number of astroglia expressing both immunoreactivities and the intensity of staining was maximal at the 14th day and remained at the same level at the 28th day. Our data suggest that the astroglial IL-1beta and IL-6 may affect the neurodegeneration of CA1 neurons in the ischemic hippocampus and that the prolonged proinflammatory effects of IL-1beta prevail over the presumed protective action of IL-6.

GM1 ganglioside potentiates trimethyltin-induced expression of interleukin-1 beta and the nerve growth factor in reactive astrocytes in the rat hippocampus: an immunocytochemical study

This study demonstrates potentiation by GM1 ganglioside treatment of trimethyltin (TMT) induced reactivity of astrocytes, and the expression of astroglial interleukin-1 beta (IL-1 beta) and nerve growth factor (NGF) immunoreactivities in the rat hippocampus. GM1 treatment also results in an increase of the number of IL-1 beta and NGF immunoreactive astrocytes. Both the intensity of gliosis and stimulation of IL-1 beta and NGF expression in astrocytes mostly occurs in the regions of heaviest neurodegeneration in the hippocampus (CA4/CA3c and CA1). It is tempting to assume that enhancement of astroglial NGF expression by GM1 ganglioside may play a role in the protective action of GM1 against neurotoxic insult.

A study of the pharmacokinetics and tissue residues of an oral trimethoprim/sulphadiazine formulation in healthy pigs

Twenty-six healthy female pigs weighing 19.5-33 kg were used in three separate experiments. The animals were fed individually twice a day. Trimethoprim/sulphadiazine (TMP/SDZ) formulation was added to feed in the amount of 6 mg/kg bw (TMP) and 30 mg/kg bw (SDZ). TMP and SDZ concentrations in blood plasma, muscles, liver and kidneys were measured. Pharmacokinetic parameters show that the absorption of TMP from the alimentary tract in pigs is faster than the absorption of SDZ, and the elimination of TMP is slower than that of SDZ. The absorption half-lives were 0.96 (TMP) and 2.24 h (SDZ), whereas elimination half-lives were 5.49 (TMP) and 4.19 h (SDZ). The observed TMP:SDZ ratios in blood plasma after multiple dose administration ranged from 1:11.4 to 1:23.2. One day after administration of the last dose of TMP/SDZ the plasma concentration ratio was 1:15.5, but in muscles, liver and kidneys it was much lower: 1:0.79, 1:0.14 and 1:1.53 respectively. The absolute TMP and SDZ tissue concentrations 1 day after the last multiple dose administration were very low (maximum TMP: 0.29 micrograms/g in liver; maximum SDZ: 0.23 micrograms/g in kidneys). Neither drug was detected in any tissue 8 days after the last administration of TMP/SDZ. Based on our results, it was concluded that there is no support for the TMP:SDZ pharmaceutical ratio 1:5 in oral formulations of these compounds for pigs. The administration oral TMP/SDZ formulations once a day may result in the absolute tissue concentrations of these drugs being too low for antibacterial activity. The withdrawal period for such an oral TMP/SDZ formulation for pigs (according to accepted guidelines in Europe for MRL of TMP < 0.05 mg/kg of tissue) should not be less than 5 days.

Difluoromethylornithine counteracts lesion-induced astrogliosis in rat hippocampus: enhancement of inhibitory effect by combined treatment with GM1 ganglioside

The effect of difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), the rate limiting enzyme of polyamine biosynthesis, and its combined action with GM1 ganglioside, was studied on the GFAP content in a model of remote astrogliosis evoked in the hippocampus by lateral fimbria transection. DFMO markedly suppressed hippocampal gliosis as measured by GFAP immunoblotting seven days postsurgery. Combined treatment with DFMO and GM1 ganglioside--a substance which alone also counteracts hippocampal gliosis, produced a stronger suppressive effect than DFMO. The results support the hypothesis of a causal link between lesion induced events: polyamine biosynthesis and astroglial reaction. Potentiation of the inhibitory effect of DFMO by GM1 ganglioside suggests that the latter does not act through the mechanism involving ODC suppression.

Axonal accumulation of p75NTR and TrkA in the septum following lesion of septo-hippocampal pathways

Septal cholinergic neurones depend on trophic support by nerve growth factor (NGF) which can rescue them from injury-induced degeneration. Since NGF exerts its effects via p75NTR and TrkA receptors coexpressed in vast majority of these neurones and down-regulated without NGF treatment after injury, in this study we aimed to examine how does the lesion to the cholinergic tracts affect distribution of both types of receptor proteins in damaged fibres. Early changes (two and seven days) were examined immunocytochemically within the septum and supracallosal stria after unilateral lesion to the supracallosal area and cingulum transecting some septal cholinergic efferents. We found accumulation of p75NTR and TrkA immunoreactive material (so-called "pile-up") within axonal segments of distended appearance proximal to the transection at two days postlesion and its translocation towards cell bodies seven days postsurgery. We observed p75NTR pile-up to be more intense than TrkA, which may indicate different cellular concentrations of both receptors. Receptor pile-up resembled acetylcholinesterase pile-up reported previously, suggesting a common response mechanism involving axonal transport disturbances.

Trimethyltin-induced plastic neuronal changes in rat hippocampus are accompanied by astrocytic trophic activity

Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been reported to induce plastic rearrangements of neuronal elements but the factors that direct these responses are unknown. To assess the possible involvement of nerve growth factor (NGF) in the phenomenon we evaluated the presumable changes in the expression pattern of NGF immunoreactivity (NGF-IR) in rat hippocampus 21 days after administration of TMT (8 mg/kg, i.p.) when reactive changes are fully developed. Immunolabelling for TrkA known to mediate biological effects of NGF and for GFAP to identify astroglial cells as a one of presumed source of postinjury produced factors was carried out on adjacent sections to establish the relation between expression of these proteins. In control hippocampus NGF-IR and TrkA-IR were localized in neurons and/or neuropil. After exposure to TMT remarkable non-neuronal expression of both proteins was observed. The distribution pattern of NGF, TrkA and GFAP overlapped suggesting that reactive astrocytes may not only produce NGF but also may become responsive to this neurotrophin. Zones of extensive NGF and TrkA astroglial expression corresponded to areas of axonal-dendritic rearrangements reported earlier. The data suggest that astroglia-derived trophic activity may be involved in neuronal plastic events associated with treatment with TMT.

Bilateral gliosis in unilaterally lesioned septohippocampal system: changes in GFAP immunoreactivity and content

Unilateral damage to the lateral fimbria led to a bilateral gliosis in the septum and hippocampus. The gliosis was manifested by an increase in GFAP staining, accompanied by an increased number of glial fibrillary acidic protein (GFAP)(+) cells and GFAP content; the latter however was not visible in the contralateral septum. In general, the contralateral reaction appeared weaker than the ipsilateral one. The pattern of contralateral increase in GFAP-immunoreactivity (IR) matched almost exactly that observed on the ipsilateral side in the hippocampus (the most evident increase was seen in the oriens and pyramidal layers of cornu Ammonis 3 and in polymorphic area of gyrus dentatus). In the septum the bilateral increase in GFAP-IR was mainly visible in the dorsolateral quadrant of the structure; however in the ipsilateral side it spread over the whole half of the structure. The astrocytic responses in the septum and hippocampus were not equivalent: they differed mainly with regard to the increase of GFAP(+) cells (over 300% of control in the anterior part of the septum and only about 120% in the dorsal hippocampus). The differences between the percentage increases of other gliotic indices: GFAP-IR and GFAP content. Various possibilities that may account for the occurrence of contralateral gliosis are discussed, the most plausible being the contribution of interhemispheric and intraseptal links and the action of some diffusible agents. We suggest that bilateral gliosis may have an impact on compensatory postlesion processes, possibly by providing trophic support to impaired neurons.

Differential effects of GM1 ganglioside treatment on glial fibrillary acidic protein content in the rat septum and hippocampus after partial interruption of their connections

The glial fibrillary acidic protein (GFAP) content was investigated using immunoblotting techniques in the septum and hippocampus of the rat after bilateral lateral fimbria transection. Seven days after surgery GFAP content increased significantly both in the septum (140% of control) and hippocampus (120% in dorsal, the less denervated, and 145% in the most denervated ventral part), indicating the occurrence of reactive gliosis. The GM1 treatment caused statistically significant attenuation of GFAP increment in all hippocampal parts. In contrast, GM1 treatment has no influence on the increase of GFAP content in the septum. Results suggest a differential effect of GM1 on the two gliotic reactions formed as a consequence of the lesion at the level of the source of innervation (septum) and the target (hippocampus).

Nerve growth factor affects uninjured, adult rat septohippocampal cholinergic neurons

The effect of nerve growth factor on the intact versus injured septohippocampal cholinergic system of adult rats was studied. Nerve growth factor was continuously infused into the lateral ventricle of adult uninjured rats or rats that had received unilateral partial transection of the fimbria. Controls (operated and unoperated) received intraventricular infusion of cytochrome c. After 2 weeks of nerve growth factor or cytochrome c treatments, choline acetyltransferase and acetylcholinesterase activities were measured in the septal area and in the hippocampus (divided into dorsal, medial and ventral parts). The continuous infusion of nerve growth factor resulted in a marked dose-dependent increase of choline acetyltransferase activity in both septum and hippocampus of adult unlesioned rats. In lesioned rats the nerve growth factor treatment was capable of inducing choline acetyltransferase activity in the hippocampus of not only the lesioned but also the unlesioned side, as well as in the septal area. In addition, nerve growth factor affected choline acetyltransferase activity differently in the hippocampus of the operated side with respect to the contralateral side or in unoperated animals. The chronic infusion of nerve growth factor did not affect acetylcholinesterase activity in the septum or in the hippocampus of either lesioned or unlesioned rats. The present findings indicate that nerve growth factor is capable of modulating the function of not only damaged but also normal adult forebrain cholinergic neurons. This suggests that nerve growth factor may modulate the function of these neurons in adulthood.

Effect of GM1 ganglioside treatment on postlesion responses of cholinergic enzymes in rat hippocampus after various partial deafferentations

The effect of intramuscular administration of monosialoganglioside (GM1) on postlesion responses of choline acetyltransferase and acetylcholinesterase activity in partially deafferented rat hippocampus was studied at various survival times. Lesions partially destroying the medioventral, septal area, or lesions performed in supracallosal stria including corpus callosum and cingulum evoked cholinergic denervation of the hippocampus, while those made in entorhinal cortex resulted in partial glutamatergic deafferentation. GM1 treatment potentiates the responses of both cholinergic enzymes, independently of whether the partial deafferentation was homo- or heterotypical. These data indicate that GM1 may facilitate the regrowth of new cholinergic nerve terminals. However, an effect on other compensatory processes, especially in the first postoperative period, is also possible.

[Analysis of clinical and social features in a group of epileptics with frequent seizures]

A group of 50 epileptics (group C) with frequent seizures refractory to treatment was studied. The control group (R) comprised 50 cases with rare seizures. It was found that despite systematic treatment (with full therapeutic doses) and frequent changes of drugs the frequency of seizures was not reduced in group C. The analysis of clinical features of both groups showed that group C as compared with group R had more patients with temporal lobe seizures, neurological abnormalities, low intelligence quotient, changed background activity in EEG and longer duration of the disease. These data may suggest a greater number of cases with detectable organic brain lesions among patients with frequent seizures.