Upgrade of ductal carcinoma in situ on core biopsies to invasive disease at final surgery: a retrospective review across the Scottish Breast Screening Programme.

AIM: To identify factors affecting upgrade rates from B5a (non-invasive) preoperative core biopsies to invasive disease at surgery and ways to improve screening performance. MATERIAL AND METHODS: This was a retrospective analysis of 1252 cases of B5a biopsies across all six Scottish Breast Screening Programmes (BSPs), ranging between 2004 and 2012. Final surgical histopathology was correlated with radiological and biopsy factors. Data were analysed using basic Microsoft Excel and standard Chi-squared test used for evaluating statistical significance. RESULTS: B5a upgrade rates for the units ranged from 19.2% to 29.2%, with an average of 23.6%. Mean sizes of invasive tumours were small (3-11 mm). The upgrade rate was significantly higher for cases where the main mammographic abnormality was mass, distortion, or asymmetry, compared with micro-calcification alone (33.2% versus 21.7%, p = 0.0004). The upgrade rate was significantly lower with the use of large-volume vacuum-assisted biopsy (VAB) devices than 14 G core needles (19.9% versus 26%, p = 0.013); in stereotactic than ultrasound-guided biopsies (21.2% versus 36.1%, p < 0.001). Heterogeneity of data from different centres limited evaluation of other potential factors. CONCLUSION: Upgrade rates are lower for cases with micro-calcification as the sole mammographic feature with the use of VAB devices. Nevertheless, there is variation in practice across Scottish BSPs, including first-line biopsy technique and/or device; and it is of interest that a few centres maintain low upgrade rates despite not using VAB routinely for biopsy of micro-calcification.

Differentiating benign from malignant solid breast masses: value of shear wave elastography according to lesion stiffness combined with greyscale ultrasound according to BI-RADS classification.

BACKGROUND: The aim of this study was to assess the performance of shear wave elastography combined with BI-RADS classification of greyscale ultrasound images for benign/malignant differentiation in a large group of patients. METHODS: One hundred and seventy-five consecutive patients with solid breast masses on routine ultrasonography undergoing percutaneous biopsy had the greyscale findings classified according to the American College of Radiology BI-RADS. The mean elasticity values from four shear wave images were obtained. RESULTS: For mean elasticity vs greyscale BI-RADS, the performance results against histology were sensitivity: 95% vs 95%, specificity: 77% vs 69%, Positive Predictive Value (PPV): 88% vs 84%, Negative Predictive Value (NPV): 90% vs 91%, and accuracy: 89% vs 86% (all P>0.05). The results for the combination (positive result from either modality counted as malignant) were sensitivity 100%, specificity 61%, PPV 82%, NPV 100%, and accuracy 86%. The combination of BI-RADS greyscale and shear wave elastography yielded superior sensitivity to BI-RADS alone (P=0.03) or shear wave alone (P=0.03). The NPV was superior in combination compared with either alone (BI-RADS P=0.01 and shear wave P=0.02). CONCLUSION: Together, BI-RADS assessment of greyscale ultrasound images and shear wave ultrasound elastography are extremely sensitive for detection of malignancy.

Proteasome inhibition overcomes the resistance of renal cell carcinoma cells against the PPARgamma ligand troglitazone.

In order to analyze the effects of peroxisome proliferator-activated receptor-gamma (PPARgamma) activation on renal cell carcinomas we utilized several cell lines that were treated with the high affinity PPARgamma agonist, troglitazone. Incubation of RCC cells with troglitazone resulted in reduced secretion of growth factors that was due to the inhibition of MAP kinase signaling and reduced nuclear localized expression of relB and HIF1alpha. Interestingly, the cell lines used showed a different sensitivity towards apoptosis induction that did not correlate with the inhibition of growth factors or expression of pro- and antiapoptotic molecules. To overcome this resistance the cells were treated with a combination of troglitazone and the proteasome inhibitor, bortezomib. The combination of both compounds induced apoptosis even in cells resistant to both agents alone, due to increased induction of ER-stress and caspase-3 mediated cell death.

Zoledronic acid inhibits the function of Toll-like receptor 4 ligand activated monocyte-derived dendritic cells.

Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate with antitumor activity used to treat patients with malignant diseases. ZA treatment induces, as a side effect, inflammatory responses, which are accompanied by expansion of gammadelta T cells. In our study, we analyzed the function and differentiation of monocyte-derived immature and lipopolysaccharide (LPS)-stimulated dendritic cells (moDCs) treated with different ZA concentrations, which are achieved in patients. We found that moDC activation with TLR4 ligand LPS is modulated by ZA. The expression of maturation markers was diminished with increasing ZA levels upon LPS activation. The migratory capacity, interleukin-12 secretion and generation of cytotoxic- T-cell responses were reduced at higher ZA levels. Increasing ZA concentrations downregulated nuclear factor-kappaB family members and interferon-regulatory factor (IRF)-3. Surprisingly, in immature moDCs, low ZA concentrations caused upregulation of RelB, c-Rel, IRF-3 and IRF-8. We conclude that ZA concentrations used to treat patients have inhibitory effects on DC activation. This might lead to immunosuppression or result in infectious complications.

Hyperphosphorylated protein tau is restricted to neurons devoid of perineuronal nets in the cortex of aged bison.

Hyperphosphorylated tau in the cortex and hippocampal formation of two aged bisons was characterized by its immunoreactivity to the phospho-epitope-recognizing monoclonal antibodies AT8, AT100, PHF-1 and TG-3. Gallyas silver staining revealed sparsely scattered cortical tangles and neuropil threads. In dual-peroxidase staining experiments, the immunocytochemical detection of vulnerable neurons was combined with the demonstration of chondroitin sulphate proteoglycan-rich perineuronal nets of the extracellular matrix. Such polyanionic lattice-like neuronal coatings were revealed lectin- and immunocytochemically. Hyperphosphorylated tau was exclusively observed in neurons devoid of perineuronal nets. The present findings in the aged bison parallel previously obtained results from a quantitative study of human brains affected by Alzheimer's disease. In conclusion, the low susceptibility of different types of neurons to the abnormal phosphorylation of tau corresponds to high proportions of certain chondroitin sulphate proteoglycans in their microenvironment.

Quantitative phylogenetic constancy of cerebellar Purkinje cell morphological complexity.

Golgi-stained material of cerebellar cortices from 17 species was examined by measuring the fractal dimensions of the borders of Purkinje cells, which is a quantitative, objective measure of morphological complexity. Nine species (from birds to man) were chosen for a comparison with ANOVA and no statistically significant differences were found in their fractal dimensions. In contrast, a wide range of differences was found in the membrane areas across species lines. The Sholl coefficient, a measure of branch formation and termination away from the soma, showed no consistent pattern for each cell. We interpret our results as indicating a constancy in morphological cellular complexity of Purkinje cells during late evolutionary time.

Golgi and Nissl studies of the visual cortex of the bottlenose dolphin.

Nissl, Golgi and fibre preparations were made of the cerebral cortex of the lateral gyrus of the bottlenose dolphin (Tursiops truncatus) in the region where visual evoked potentials have been reported (Sokolov et al., '72; Ladygina et al., '78). In the adult the visual cortex is relatively thin (average about 1,300 micron) for so large a brain (fixed brain weight for a typical adult in our series was 1,330 g). Layers I, III, and VI are wide and represent three-quarters of the total cortical thickness. Layer I contains few cell bodies, while III and VI have a variety of pyramidal and nonpyramidal neurons. Layers II and V are narrow and contain striking palisades of darkly staining pyramidal cells that are particularly large in layer V. No clearly demarcated layer IV is present in the adult dolphin visual cortex. Many of the neurons identified with the Golgi technique are typical of pyramids in other mammals, with a single apical dendrite and a bouquet of basal dendrites, mostly highly spiny. Others are unusual in having bifurcated or oblique apical dendrites. Typical large and small spiny and nonspiny stellates are also found, mainly in layers III and VI. In addition various forms of spindle-shaped, bipolar and multipolar neurons are found in most layers. An 18-day-old brain shows signs of immaturity in its visual cortex. It is thinner (970 micron) and on average its neurons are smaller, paler, and more densely packed. Especially the pyramids of layer V are much smaller than in the adult. Also, a distinct "granular" band occurs between layers III and V and seems to be a rudimentary layer IV. At 3 years of age most of the adult features have developed, but layer IV is still detectable. No striking differences were observed in cell and fibre architecture between the cortex of the lateral gyrus and that of the so-called "calcarine" area that has also been considered as "visual." We concluded that, although different in many respects from other mammalian visual cortices, that of the dolphin is apparently well developed and differentiated.

Two distinct populations of cholinergic neurons in the septum of raccoon (Procyon lotor): evidence for a separate subset in the lateral septum.

The present study focused on cholinergic neurons in the lateral septal region of the raccoon detected by choline acetyltransferase (ChAT)-immunostaining. For comparison of the cholinergic neurons of the medial and lateral septal nuclei, soma sizes were measured, and several antibodies were applied that differentially characterize these cells in several species: low-affinity neurotrophin receptor p75 (p75(NTR)), calbindin-D(28k) (CALB), and constitutive nitric oxide synthase (cNOS). To compare the basic organization of the raccoon septum with that in other mammals, parvalbumin (PARV) immunocytochemistry and Wisteria floribunda-agglutinin (WFA) lectin histochemistry also were used in double-staining experiments. The ChAT-immunoreactive neurons of the rostral lateral septum are arranged in laminae. Accumulations of cholinergic varicosities, often clearly ensheathing noncholinergic neurons, occupy small territories of the rostral septum. Such regions become larger in the caudal septum. They are assumed to correspond to the septohippocampal and septofimbrial nuclei of the rat. In contrast to the large medial septal cholinergic neurons of the raccoon that contain p75(NTR), CALB, and cNOS, the cholinergic neurons of the lateral septum are smaller and do not express these markers. A further peculiarity is that the region of the lateral septum that contains cholinergic neurons corresponds to WFA-labelled extracellular matrix zones that contain chondroitin sulfate proteoglycans. In addition to clustered thread- or ring-like accumulations of the WFA, sparsely labelled perineuronal nets surround the lateral septal cholinergic neurons. Similar to other species that have been investigated, perineuronal nets are completely absent around cholinergic cells of the medial septum. The PARV-containing neurons of this region, however, are enwrapped by perineuronal nets as they are in the rat. Within the medial septum, the PARV-containing neurons are restricted to ventral bilateral territories that are devoid of cholinergic cells. In this respect, they differ from the more vertically arranged PARV-containing medial septal cells in rodents and primates. Apart from striking differences in numbers and distribution patterns, the raccoon lateral septal cholinergic neurons resemble those detected by Kimura et al. (Brain Res [1990] 533:165-170) in the ventrolateral septal region of rat and monkey. Their participation in the functions of the lateral septum remains to be elucidated.

Mapping of perineuronal nets in the rat brain stained by colloidal iron hydroxide histochemistry and lectin cytochemistry.

Net-like structures, visualized with the Golgi technique and several histochemical and immunocytochemical methods, have been described to ensheath somata, parts of dendrites and axon initial segments of various types of neurons. The origin and function of these perineuronal nets have been controversially discussed. Recently, it was confirmed that they are glia-associated. In the present study such perineuronal nets were demonstrated by using colloidal iron hydroxide staining for detection of polyanionic components and the plant lectins Vicia villosa agglutinin and Wisteria floribunda agglutinin with affinity for N-acetylgalactosamine. This paper shows their distribution patterns and the occurrence of regional specialization of these nets which might provide a basis to suggest functional implications of these structures. Perineuronal nets were found in more than 100 brain regions, such as neocortex, hippocampus, piriform cortex, basal forebrain complex, dorsal lateral septal nucleus, lateral hypothalamic area, reticular thalamic nucleus, zona incerta, deep parts of superior and inferior colliculus, red nucleus, substantia nigra, some tegmental nuclei, cerebellar nuclei, dorsal raphe and cuneiform nuclei, central gray, trochlear nucleus, pontine and medullar reticular nuclei, superior olivary nucleus and vestibular nuclei. Neurons enwrapped by perineuronal nets not only differ in morphology but also in transmitter content. In neocortical and hippocampal regions there occurs a much higher number of perineuronal nets ensheathing non-pyramidal cells than in paleocortical structures. Most subcortical regions containing perineuronal nets were found to be integrated in motor functions. The findings are discussed with respect to known electrophysiological data of cell types described in our investigation as net-associated. There are some indications that such cells may represent fast firing types.

Cortical areas abundant in extracellular matrix chondroitin sulphate proteoglycans are less affected by cytoskeletal changes in Alzheimer's disease.

In the human brain, the distribution of perineuronal nets occurring as lattice-like neuronal coatings of extracellular matrix proteoglycans ensheathing several types of non-pyramidal neurons and subpopulations of pyramidal cells in the cerebral cortex is largely unknown. Since proteoglycans are presumably involved in the pathogenesis of Alzheimer's disease, we analysed the distribution pattern of extracellular chondroitin sulphate proteoglycans in cortical areas, including primary motor, primary auditory and several prefrontal and temporal association areas, in normal human brains and in those showing neuropathological criteria of Alzheimer's disease. In both groups, neurons with perineuronal nets were most numerous in the primary motor cortex (approximately 10% in Brodmann's area 4) and in the primary auditory cortex as a representative of the primary sensory areas. Their number was lower in secondary and higher order association areas. Net-associated pyramidal cells occurred predominantly in layers III and V in motor areas, as well as throughout lower parts of layer III in the primary auditory cortex and neocortical association areas. In the entorhinal cortex, net-associated pyramidal cells were extremely rare. In brains showing hallmarks of Alzheimer's disease, the characteristic patterns of hyperphosphorylated tau protein, stained with the AT8 antibody, largely excluded the zones abundant in perineuronal nets and neuropil-associated chondroitin sulphate proteoglycans. As shown in double-stained sections, pyramidal and non-pyramidal neurons ensheathed by perineuronal nets were virtually unaffected by the formation of neurofibrillary tangles even in severely damaged regions. The distribution patterns of amyloid B deposits overlapped but showed no congruence with that of the extracellular chondroitin sulphate proteoglycans. It can be concluded that low susceptibility of neurons and cortical areas to neurofibrillary changes corresponds with high proportions of aggregating chondroitin sulphate proteoglycans in the neuronal microenvironment.

Perineuronal nets in the rhesus monkey and human basal forebrain including basal ganglia.

Perineuronal nets of extracellular matrix have been shown to characterize the microenvironment of individual neurons and the chemoarchitecture of brain regions such as basal forebrain nuclei. Previous work has also demonstrated that neurons in the human cerebral cortex ensheathed by perineuronal nets rarely undergo cytoskeletal changes in Alzheimer's disease, suggesting a neuroprotective effect of extracellular matrix components. It is not known, however, whether or not perineuronal nets are absent in the microenvironment of the cholinergic basal forebrain neurons that are involved early in the cascade of neurodegeneration in humans. Therefore, the present study was undertaken to examine the distribution patterns of perineuronal nets in the basal forebrain of the higher primates, rhesus monkey and human. Cytochemical staining was performed with the lectin Wisteria floribunda agglutinin and a polyclonal antibody to core proteins of chondroitin sulfate proteoglycans in the perfusion-fixed tissue of rhesus monkeys. In human brains, perineuronal nets were only stained with the immunoreaction for chondroitin sulfate proteoglycans. The results showed similar characteristics in distribution patterns of perineuronal nets in the medial septum, the diagonal band of Broca, the basal nucleus of Meynert (Ch1-Ch4), the lateral septum, the caudate-putamen, and the globus pallidus in both species. Double-labelling revealed that the vast majority of cholinergic neurons, labelled either with antibodies to choline acetyltransferase or the low-affinity neurotrophin receptor p75(NTR), were not ensheathed by perineuronal nets. A small subpopulation of net-associated neurons in close proximity to or intermingled with cholinergic neurons of the Ch1-Ch4 cell groups was found to be immunoreactive for parvalbumin. In the caudate-putamen, a large number of the parvalbumin-positive neurons were surrounded by perineuronal nets, whereas in the external and internal segments of the globus pallidus the coincidence of both markers was nearly complete. The study demonstrates that perineuronal nets of extracellular matrix are associated with different types of non-cholinergic neurons in the primate basal forebrain. The absence of nets around cholinergic basal forebrain neurons may be related to their slow modulatory activity but may also contribute to their susceptibility to degeneration in Alzheimer's disease.

Measurement of pulmonary density by means of X-ray computerized tomography. Relation to pulmonary mechanics in normal subjects.

We examined the relationship between pulmonary density, measured with computerized tomography, and pulmonary mechanics (static pulmonary volume; pulmonary resistance) in 39 normal subjects (20 nonsmokers and 19 smokers). Pulmonary density decreased with increasing static elastic recoil pressure, and smokers consistently showed higher pulmonary density than nonsmokers. Pulmonary density, measured at full inspiration, correlated inversely with total lung capacity. Pulmonary density showed a ventrodorsal gradient, which was greater at low elastic recoil pressure than at high recoil pressure. The study shows that pulmonary density is related to the mechanical properties of the lung in normal subjects. Increased pulmonary density appears to be a sensitive indicator of pulmonary damage induced by smoking. Further studies of the relationship between pulmonary density and pulmonary mechanics in disease seem warranted.

Phylogenetic diversity of the expression of the microtubule-associated protein tau: implications for neurodegenerative disorders.

The microtubule-associated protein tau regulates the dynamic stability of the neuronal cytoskeleton by interacting with microtubules. It is encoded by a single gene, but expressed in a variety of isoforms due to differential RNA splicing. Six isoforms can be found in the human central nervous system. These isoforms differ in their ability to promote the assembly of microtubules as well as in their capacity to stabilize existing microtubule structures. Furthermore, some of the isoforms of tau are specifically involved in the pathogenesis of neurodegenerative disorders. Thus, splicing of tau might critically influence the physiological functions of tau protein as well as the pathogenesis of neurodegenerative diseases with tauopathy. The present study addresses the differential expression of the six isoforms of tau in the central nervous system of 12 mammalian species including Homo sapiens. The occurrence of each of the six tau isoforms was highly variable. However, species that were phylogenetically related expressed a similar pattern of tau isoforms. These results suggest a phylogenetic descent of splicing paradigms, which can be matched with known phylogenetic concepts based on morphological and molecular genetical studies. Especially, the unique expression pattern of tau isoforms in the human central nervous system implicates a possible link to the particular vulnerability of humans to neurodegenerative disorders with tauopathy, namely Alzheimer's disease, frontotemporal dementia and Pick's disease.

Measurement of lung density by x-ray computed tomography. Relation to lung mechanics in workers exposed to asbestos cement.

We measured lung density by means of x-ray computed tomography and lung mechanics in 33 workers exposed to asbestos cement and in 39 normal subjects. The exposed group showed evidence of lung fibrosis with reduced static lung volumes and lung compliance, although only three subjects had signs of interstitial fibrosis at standard chest radiography. Lung density was significantly increased in the exposed workers compared to control subjects, with greater differences between nonsmokers than between smokers. Lung density correlated inversely with static lung volumes. There was no appreciable difference in the regional distribution of lung density between exposed workers and control subjects. We conclude that lung density is often increased in workers with mild asbestosis, even in the presence of a normal chest radiograph. Measurement of lung density may be of value in the evaluation of asbestos-exposed workers for assessment of the extent of parenchymal disease.

Low expression of extracellular matrix components in rat brain stem regions containing modulatory aminergic neurons.

Extracellular matrix proteoglycans, particularly those accumulated in perineuronal nets (PNs), have been shown to form characteristic distribution patterns in cortical and subcortical regions of adult mammals. Their involvement in sustaining mechanisms that are especially related to fast activities of neurons has been discussed as one of the possible functions. The present study deals with the spatial organization of extracellular matrix proteoglycans in brain stem regions that contain aminergic neurons, such as substantia nigra, ventral tegmental area (VTA), raphe nuclei and locus coeruleus (LC). As these nuclei are known to influence brain activity by modulatory functions exerting patterns of slow electric activity, it could be expected that PNs would be absent around aminergic cells. The staining of PNs with Wisteria floribunda agglutinin (WFA) was combined with the detection of catecholaminergic neurons by tyrosine hydroxylase immunoreactivity and of serotonergic neurons by tryptophan hydroxylase (TH) immunoreactivity using double fluorescence microscopy. It was found that the catecholaminergic and serotonergic neurons in the nuclear accumulations, as well as those scattered in adjacent regions, were not ensheathed by PNs. In contrast, several non-aminergic neurons intermingled with aminergic neurons in the raphe nuclei, in the substantia nigra pars compacta (SNC) and in the VTA, as well as many cells in the reticular part of the substantia nigra, were found to be surrounded by PNs. It can be concluded from these results that the absence of PNs around aminergic brain stem neurons, also previously shown for cholinergic basal forebrain neurons, appears as a characteristic feature common to cells that exert slow modulatory functions.

Projection of non-cholinergic basal forebrain neurons ensheathed with perineuronal nets to rat mesocortex.

The existence of non-cholinergic (GABAergic) components in the septo-hippocampal system but also in basal forebrain projections terminating in the olfactory bulb and certain cortical areas has been documented by several authors using retrograde and anterograde tracing techniques. On the other hand, the basal forebrain also contains a high number of mainly parvalbumin-positive neurons ensheathed by a lattice-like matrix of polyanionic proteoglycans forming so-called perineuronal nets of as yet unknown function. By a combination of retrograde tracing using Fluoro-Gold injection into mesocortical areas of rats and staining of perineuronal nets by Wisteria floribunda agglutinin (WFA) the present study describes the projection pattern and distribution of non-cholinergic projection neurons characterized by perineuronal nets in the anterior parts of the basal forebrain complex (medial septal nucleus, nucleus of the diagonal band of Broca, magnocellular preoptic nucleus). After tracer injection into the cingulate cortex labelled net-associated neurons were distributed within the rostrocaudal extension of the basal forebrain complex but were predominantly found in the horizontal limb of the diagonal band of Broca. Retrograde labelling of neurons with perineuronal nets after tracer injection into the retrosplenial cortex was more pronounced in the medial septum. Choline acetyltransferase-immunoreactive (ChAT-ir) projection neurons were in no case associated with perineuronal nets. The results demonstrate that a large portion of the non-cholinergic projection neurons of the basal forebrain are endowed with a specialized microenvironment of proteoglycans and form a strong input system of mesocortical components of the limbic system.

Principles of rat subcortical forebrain organization: a study using histological techniques and multiple fluorescence labeling.

In the present study, we introduce new views on neuro- and chemoarchitectonics of the rat forebrain subcortex deduced from traditional and current concepts of anatomical organization and from our own results. It is based on double and triple immunofluorescence of markers for transmitter-related enzymes, calcium-binding proteins, receptor proteins, myelin basic protein (MBP) and neuropeptides, and on histological cell/myelin stains. The main findings can be summarized as follows: (i) the dorsal striatum of rat and other myomorph rodents reveals a small caudate equivalent homotopic to the caudate nucleus (C) of other mammals, and a large putamen (Pu). (ii) Shell and core can be distinguished also in the 'rostral pole' of nucleus accumbens (ACC) with the calretinin/calbindin and neuropeptide Y (NPY) immunostaining. The shell reveals characteristics of a genuine striatal but not of an extended amygdala (EA) subunit. (iii) EA and lateral septum show striking similarities in structure and fiber connections and may therefore represent a separate parastriatal complex. (iv) The meandering dense layer (DL) of olfactory tubercle (OT) forms longitudinal gyrus- and sulcus-like structures converging in its rostral pole. (v) The core regions of the islands of Calleja that border the ventral pallidum (VP) sharing some of its features are invaded by myelinated fibers of the medial forebrain bundle (MFB). The island of Calleja magna is also apposed to an inconspicuous, slender dorsal appendage of VP. (vi) The VP is composed of a large dorsal reticulated part traversed by the myelinated GABAergic parvalbumin-immunoreactive axons of the MFB and a slender ventral non-reticulate part close to the islands of Calleja. (vii) Considering their close association to the limbic system, ventral striatum (VS) and VP may represent the oldest part of basal ganglia, whereas dorsal striatopallidal subunits were progressively developed in parallel to the growing neocortical influence on motor behavior.

Wisteria floribunda agglutinin-labelled nets surround parvalbumin-containing neurons.

Net-like structures surrounding several types of neurones contain glycoconjugates which are detectable by lectins specific for N-acetylgalactosamine. Wisteria floribunda agglutinin (WFA) was introduced as a further marker for the visualization of such perineuronal nets, which were also revealed in regions of the rat brain where these structures could not be clearly demonstrated using other lectins. The WFA-labelled perineuronal nets resembled in detail those which could be visualized using Vicia villosa agglutinin, colloidal iron or hyaluronectin as markers. Furthermore, WFA-stained perineuronal net components appeared to be similar to proteoglycan-immunoreactive structures. Dual-peroxidase experiments and fluorescence double labelling demonstrated that WFA-binding structures frequently ensheath GABAergic neurons containing the calcium-binding protein parvalbumin in the areas investigated.

Co-occurrence of perineuronal nets with GABAA receptor alpha 1 subunit-immunoreactive neurones in the rat septal region.

The immunocytochemical demonstration of the GABAA receptor alpha 1 subunit was combined with the Wisteria floribunda agglutinin staining of lattice-like extracellular matrix components--known as perineuronal nets--in the rat basal forebrain. Both were found to be co-localized in the septal-diagonal band region (e.g. in the medial septum, 96%), but only exceptionally in the ventral pallidum (3-10%) and nowhere in other basal forebrain subdivisions. This co-occurrence of perineuronal nets with septo-hippocampal projection neurones--previously characterized as GABAergic--expressing the GABAA receptor alpha 1 subunit- as well as parvalbumin-immunoreactivity, suggests the involvement of these intra- and extraneuronal components in the fast spiking neuronal activity essential for the generation and maintenance of hippocampal theta rhythm.