Intercellular Communication in the Central Nervous System as Deduced by Chemical Neuroanatomy and Quantitative Analysis of Images: Impact on Neuropharmacology.

In the last decades, new evidence on brain structure and function has been acquired by morphological investigations based on synergic interactions between biochemical anatomy approaches, new techniques in microscopy and brain imaging, and quantitative analysis of the obtained images. This effort produced an expanded view on brain architecture, illustrating the central nervous system as a huge network of cells and regions in which intercellular communication processes, involving not only neurons but also other cell populations, virtually determine all aspects of the integrative function performed by the system. The main features of these processes are described. They include the two basic modes of intercellular communication identified (i.e., wiring and volume transmission) and mechanisms modulating the intercellular signaling, such as cotransmission and allosteric receptor-receptor interactions. These features may also open new possibilities for the development of novel pharmacological approaches to address central nervous system diseases. This aspect, with a potential major impact on molecular medicine, will be also briefly discussed.

Receptor-Receptor Interactions and Glial Cell Functions with a Special Focus on G Protein-Coupled Receptors.

The discovery that receptors from all families can establish allosteric receptor-receptor interactions and variably associate to form receptor complexes operating as integrative input units endowed with a high functional and structural plasticity has expanded our understanding of intercellular communication. Regarding the nervous system, most research in the field has focused on neuronal populations and has led to the identification of many receptor complexes representing an important mechanism to fine-tune synaptic efficiency. Receptor-receptor interactions, however, also modulate glia-neuron and glia-glia intercellular communication, with significant consequences on synaptic activity and brain network plasticity. The research on this topic is probably still at the beginning and, here, available evidence will be reviewed and discussed. It may also be of potential interest from a pharmacological standpoint, opening the possibility to explore, inter alia, glia-based neuroprotective therapeutic strategies.

The additional role of virtual to traditional dissection in teaching anatomy: a randomised controlled trial.

INTRODUCTION: Anatomy has traditionally been taught via dissection and didactic lectures. The rising prevalence of informatics plays an increasingly important role in medical education. It is hypothesized that virtual dissection can express added value to the traditional one. METHODS: Second-year medical students were randomised to study anatomical structures by virtual dissection (intervention) or textbooks (controls), according to the CONSORT guidelines. Subsequently, they applied to the corresponding gross dissection, with a final test on their anatomical knowledge. Univariate analysis and multivariable binary logistic regression were performed. RESULTS: The rate of completed tests was 76.7%. Better overall test performance was detected for the group that applied to the virtual dissection (OR 3.75 with 95% CI 0.91-15.49; p = 0.06). A comparable performance between groups in basic anatomical knowledge (p 0.45 to 0.92) but not muscles and 2D-3D reporting of anatomical structures was found, for which the virtual dissection was of tendential benefit (p 0.08 to 0.13). Medical students who applied to the virtual dissection were over three times more likely to report a positive outcome at the post-dissection test than those who applied to textbooks of topographical anatomy. This would be of benefit with particular reference to the understanding of 2D-3D spatial relationships between anatomical structures. CONCLUSION: The combination of virtual to traditional gross dissection resulted in a significant improvement of second-year medical students' learning outcomes. It could be of help in maximizing the impact of practical dissection, overcoming the contraction of economic resources, and the shortage of available bodies.

Morphometric analysis of the branching of the vascular tree in the chick embryo area vasculosa.

The chick embryo includes the area vasculosa is subdivided into 2 concentric zones, the inner transparent area pellucida vasculosa and the surrounding less transparent area opaca vasculosa, peripherally limited by the sinus terminalis. In this study, we have analyzed by a modern morphometric approach the total length of the vascular network, the number of vascular branches, of the branching points density, the modality of vessel ramification, and spatial arrangement of the vascular network in four consecutive stages of development of the area vasculosa. The results have shown that there is a significant 15% increase in the total length of the vascular network associated with a progressive increase of the number of vascular branches and of the branching points density. Moreover, the results indicated that vascular spatial disorder significantly decreased during development in area vasculosa, suggesting a more uniform occupancy of the tissue by the vascular pattern. Finally, a more regular pattern of branching was observed, as indicated by the significant decrease of topological disorder of the vascular tree.

Growth Factors in the Carotid Body-An Update.

The carotid body may undergo plasticity changes during development/ageing and in response to environmental (hypoxia and hyperoxia), metabolic, and inflammatory stimuli. The different cell types of the carotid body express a wide series of growth factors and corresponding receptors, which play a role in the modulation of carotid body function and plasticity. In particular, type I cells express nerve growth factor, brain-derived neurotrophic factor, neurotrophin 3, glial cell line-derived neurotrophic factor, ciliary neurotrophic factor, insulin-like-growth factor-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-α and -ß, interleukin-1ß and -6, tumor necrosis factor-α, vascular endothelial growth factor, and endothelin-1. Many specific growth factor receptors have been identified in type I cells, indicating autocrine/paracrine effects. Type II cells may also produce growth factors and express corresponding receptors. Future research will have to consider growth factors in further experimental models of cardiovascular, metabolic, and inflammatory diseases and in human (normal and pathologic) samples. From a methodological point of view, microarray and/or proteomic approaches would permit contemporary analyses of large groups of growth factors. The eventual identification of physical interactions between receptors of different growth factors and/or neuromodulators could also add insights regarding functional interactions between different trophic mechanisms.

The characteristics of the lobular arrangement indicate the dynamic role played by the infrapatellar fat pad in knee kinematics.

The infrapatellar fat pad (IFP) is an intracapsular but extrasynovial structure, located between the patellar tendon, the femoral condyles and the tibial plateau. It consists of white adipose tissue, organised in lobules defined by thin connective septa. The aim of this study is the morphometric and ultrasonographic analysis of IFP in subjects without knee pathology during flexion-extension movements. The morphometric study was conducted on 20 cadavers (15M, 5F, mean age 80.2 years). Ultrasound was performed on 24 volunteers with no history of knee diseases (5M, 19F, mean age: 45 years). The characteristics of the adipose lobules near the patellar tendon and in the deep portion of the IFP were evaluated. Numerical models were provided, according to the size of the lobules. At histological examination, the adipose lobules located near the patellar tendon were larger (mean area 12.2 mm2  ± 5.3) than those at a deeper level (mean area 1.34 mm2  ± 0.7, P < 0.001) and the thickness of the septa of the deepest adipose lobules (mean value 0.35 mm ± 0.32) was greater than that of the superficial one (mean value 0.29 mm ± 0.25, P < 0.001). At ultrasound, the IFP was seen to be composed of very large lobules in the superficial part (mean area 0.29 cm2  ± 0.17 in extension), with a significant reduction in flexion (mean area 0.12 cm2  ± 0.07, P < 0.01). The deep lobules were smaller (mean area 0.11 cm2  ± 0.08 in extension) and did not change their values (mean area 0.19 cm2  ± 0.52 in flexion, P > 0.05). In the sagittal plane, the reduction of thickness of the superficial layer (with large adipose lobules) during flexion was 20.6%, whereas that of the deep layer (with small adipose lobules) was 1.3%. Numerical simulation of vertical loads, corresponding to flexion of the knee, showed that stress mainly developed within the interlobular septa and opposed bulging of the lobules. The characteristics of the lobular arrangement of the IFP (large lobules with superficial septa in the superficial part and small lobules with thick septa in the deep one), significant changes in the areas and perimeters of the superficial lobules, and the reduced thickness of the superficial layer during flexion all indicate the dynamic role played by the IFP in knee kinematics.

Spatial distribution of mast cells and macrophages around tumor glands in human breast ductal carcinoma.

Macrophages and mast cells are usually present in the tumor microenvironment and play an important role as regulators of inflammation, immunological response and angiogenesis in the tumor microenvironment. In this study, we have evaluated macrophage, mast cell, and microvessel density in a selected group of different grade of invasive breast carcinoma tumor specimens. Furthermore, we have investigated the pattern of distribution of CD68-positive macrophages and tryptase-positive mast cells around tumor glands. Results have shown that: A) Macrophages are more numerous in G2 and G3 breast cancer stages respect to controls, the per cent of macrophages in G1 samples was comparable to the controls, and the spatial relationship between macrophages and glands (as indicated by the mean cell-to-gland distance) correlated with CD31-positive vessels. B) Mast cells in G2 and G3 tumor specimens show a significant increase in their number as compared to control samples, and their spatial distribution around the glands did not show any significant difference among groups. Overall, the results of this study confirm the important role of macrophages and mast cells in tumor progression and angiogenesis in human ductal breast cancer, and pointed out the spatial relationship between tumor macrophages and glands, and its correlation with microvascular density.

Radiological anatomy of the perforators of the gluteal region: The "radiosome" based anatomy.

BACKGROUND: The superior (SGA) and the inferior gluteal artery (IGA) perforator flaps are widely used in pressure-sore repair and in breast reconstruction. The aim was to exhaustively depict the topographical anatomy of the whole system of perforators in the buttock. METHODS: Eighty lower-extremity computed tomographic angiography (CTA) of patients (20 males/20 females, mean age 61-years old, range 38-81) were considered. The source artery, location, type, and caliber of gluteal perforators were analyzed. The location of perforators was reproduced using a standardized two-dimensional grid on the coronal plane, centered onto defined bone landmarks. We defined "radiosome" the cutaneous vascular territory of a source artery inferred through the representation of its whole perforator system at the exit point through the deep fascia. RESULTS: A mean number of 25.6 ± 5.7 perforators in the gluteal region was observed, distributed as follows: 11.6 ± 4.8(45.2%) from SGA; 7.9 ± 4.5(30.8%) from IGA; 1.5 ± 0.8(5.8%) from fifth lumbar artery; 1.2 ± 0.8(4.7%) from internal pudendal artery; 1.2 ± 1(4.8%) from lateral circumflex femoral artery; 0.3 ± 0.7(1.2%) from circumflex iliac superficial artery. At least one large (internal diameter > 1 mm) SGA septocutaneous perforator was present in 77.5% of patients. CONCLUSIONS: The gluteal region is vascularized by perforators of multiple source arteries. Septocutaneous perforators of SGA and IGA were planned along a curve drawn from the posterior-superior border of the iliac crest to the greater trochanter. The lumbar artery perforators are clustered over the apex of the iliac crest; the internal pudendal artery perforators are clustered medially to the ischiatic tuberosity. Contributions can also come from the sacral and superficial circumflex iliac arteries.

Fractal analysis of alveolarization in hyperoxia-induced rat models of bronchopulmonary dysplasia.

No papers are available about potentiality of fractal analysis in quantitative assessment of alveolarization in bronchopulmonary dysplasia (BPD). Thus, we here performed a comparative analysis between fractal [fractal dimension (D) and lacunarity] and stereological [mean linear intercept (Lm), total volume of alveolar air spaces, total number of alveoli, mean alveolar volume, total volume and surface area of alveolar septa, and mean alveolar septal thickness] parameters in experimental hyperoxia-induced models of BPD. At birth, rats were distributed between the following groups: 1) rats raised in ambient air for 2 wk; 2) rats exposed to 60% oxygen for 2 wk; 3) rats raised in normoxia for 6 wk; and 4) rats exposed to 60% hyperoxia for 2 wk and to room air for further 4 wk. Normoxic 6-wk rats showed increased D and decreased lacunarity with respect to normoxic 2-wk rats, together with changes in all stereological parameters except for mean alveolar volume. Hyperoxia-exposed 2-wk rats showed significant changes only in total number of alveoli, mean alveolar volume, and lacunarity with respect to equal-in-age normoxic rats. In the comparison between 6-wk rats, the hyperoxia-exposed group showed decreased D and increased lacunarity, together with changes in all stereological parameters except for septal thickness. Analysis of receiver operating characteristic curves showed a comparable discriminatory power of D, lacunarity, and total number of alveoli; Lm and mean alveolar volume were less discriminative. D and lacunarity did not show significant changes when different segmentation thresholds were applied, suggesting that the fractal approach may be fit to automatic image analysis.

A fractal analysis of the spatial distribution of tumoral mast cells in lymph nodes and bone marrow.

The spatial distribution of mast cells inside the tumor stroma has been little investigated. In this study, we have evaluated tumor mast cells distribution through the analysis of the morphological features of the spatial patterns generated by these cells, including size, shape, and architecture of the cell pattern. We have compared diffuse large B cells lymphoma (DLBCL) and systemic mastocytosis in two different anatomical localizations (lymph nodes for DLBCL and, respectively, bone marrow for mastocytosis). Results have indicated that, despite the high difference in size exhibited by the mast cells patterns in the two conditions, the spatial relationship between the mast cells forming the aggregates resulted similar, characterized by a significant tendency of the mast cells to self-organize in clusters.

Neuroglobin, a Factor Playing for Nerve Cell Survival.

Cell death represents the final outcome of several pathological conditions of the central nervous system and available evidence suggests that in both acute injuries and neurodegenerative diseases it is often associated with mitochondrial dysfunction. Thus, the possibility to prevent mitochondrial events involved in cell death might represent efficient tools to limit neuronal damage. In recent years, increased attention has been paid to the endogenous protein neuroglobin, since accumulating evidence showed that its high expression was associated with preserved mitochondrial function and to an increased survival of nerve cells in vitro and in vivo in a variety of experimental models of cell insult. The biological and structural features of neuroglobin and the mitochondria-related mechanisms of neuroglobin-induced neuroprotection will be here briefly discussed. In this respect, the inhibition of the intrinsic pathway of apoptosis emerges as a key neuroprotective effect induced by the protein. These findings could open the possibility to develop efficient neuroglobin-mediated therapeutic strategies aimed at minimizing the neuronal cell death occurring in impacting neurological pathologies like stroke and neurodegenerative diseases.

The anterolateral ligament of the knee: a radiologic and histotopographic study.

PURPOSE: Recent anatomic investigations of the lateral structures of the knee have rediscovered a ligament, called the antero-lateral ligament (ALL). METHODS: Ten specimens of ALL (6 M, 4 F, mean age 82.3) were sampled from bodies of the Body Donation program of the University of Padova for histological and immuno-histochemical studies. Moreover, a retrospective magnetic resonance (MR) study was carried out in 50 patients (30 M, 20 F, mean age 37.5). MR exams with a normal anatomo-radiological report were selected. RESULTS: From the microscopic point of view the ALL corresponds to a dense connective tissue (mean thickness 893 ± 423 µm), and is composed by collagen I (90 %), collagen III (5 %) and collagen VI (3 %) and scarce elastic fibers (<1 %). On MR exams, ALL appears as a thin linear structure, originating at the lateral epicondyle, running obliquely downwards and forwards, and inserting in the middle third (46 %) or inferior third (14 %) of lateral meniscus and in the lateral aspect of the proximal tibia. It was observed in 47 cases (93 %), with a mean length of 32 ± 4.6 mm and mean thickness of 1.1 ± 0.4 mm. The ALL showed low signal intensity on both T1- and T2-weighted sequences. CONCLUSION: The ALL shows the typical structure of a fibrous ligament. From the anatomo-radiological point of view the ALL is almost constantly depicted by routine 1.5-T MR scan.

A Self-Similarity Logic May Shape the Organization of the Nervous System.

From the morphological point of view, the nervous system exhibits a fractal, self-similar geometry at various levels of observations, from single cells up to cell networks. From the functional point of view, it is characterized by a hierarchical organization in which self-similar structures (networks) of different miniaturizations are nested within each other. In particular, neuronal networks, interconnected to form neuronal systems, are formed by neurons, which operate thanks to their molecular networks, mainly having proteins as components that via protein-protein interactions can be assembled in multimeric complexes working as micro-devices. On this basis, the term "self-similarity logic" was introduced to describe a nested organization where, at the various levels, almost the same rules (logic) to perform operations are used. Self-similarity and self-similarity logic both appear to be intimately linked to the biophysical evidence for the nervous system being a pattern-forming system that can flexibly switch from one coherent state to another. Thus, they can represent the key concepts to describe its complexity and its concerted, holistic behavior.

Detection of Possible Symmetries in Vascular Networks by Computer-Assisted Image Analysis.

The possible forms that vascular networks may assume are significantly constrained by complex demands in terms of efficient delivery of oxygen and resources throughout the entire body. Because of these constraints the search for systematic patterns in the structural features of vascular networks and of their correlation with physiological needs and pathological conditions (such as tumor angiogenesis) represents an important line of morphological research. In this context, symmetry properties of vascular trees received limited attention, although symmetry is a widespread phenomenon, visible in all forms and scales in natural environments, and represents a significant information to describe a shape. In the present chapter three, image analysis-based methods allowing for the detection of possible symmetry features exhibited by vascular trees will be detailed and discussed.

Receptor-receptor interactions and microvesicle exchange as mechanisms modulating signaling between neurons and astrocytes.

It is well known that astrocytes play a significant metabolic role in the nervous tissue, maintaining the homeostasis of the extracellular space and of the blood-brain barrier, and providing trophic support to neurons. In addition, however, evidence exists indicating astrocytes as important elements for brain activity through signaling exchange with neurons. Astrocytes, indeed, can sense synaptic activity and their molecular machinery responds to neurotransmitters released by neurons with cytoplasmic Ca2+ elevations that, in turn, stimulate the release of neuroactive substances (gliotransmitters) influencing nearby neurons. In both cell types the recognition and transduction of this complex pattern of signals is mediated by specific receptors that are also involved in mechanisms tuning the intercellular cross-talk between astrocytes and neurons. Two of these mechanisms are the focus of the present discussion. The first concerns direct receptor-receptor interactions leading to the formation at the cell membrane of multimeric receptor complexes. The cooperativity that emerges in the actions of orthosteric and allosteric ligands of the monomers forming the assembly provides the cell decoding apparatus with sophisticated and flexible dynamics in terms of recognition and signal transduction pathways. A further mechanism of plasticity involving receptors is based on the transfer of elements of the cellular signaling apparatus via extracellular microvesicles acting as protective containers, which can lead to transient changes in the transmitting/decoding capabilities of the target cell. This article is part of the Special Issue on "The receptor-receptor interaction as a new target for therapy".

Modulation of Neuron and Astrocyte Dopamine Receptors via Receptor-Receptor Interactions.

Dopamine neurotransmission plays critical roles in regulating complex cognitive and behavioral processes including reward, motivation, reinforcement learning, and movement. Dopamine receptors are classified into five subtypes, widely distributed across the brain, including regions responsible for motor functions and specific areas related to cognitive and emotional functions. Dopamine also acts on astrocytes, which express dopamine receptors as well. The discovery of direct receptor-receptor interactions, leading to the formation of multimeric receptor complexes at the cell membrane and providing the cell decoding apparatus with flexible dynamics in terms of recognition and signal transduction, has expanded the knowledge of the G-protein-coupled receptor-mediated signaling processes. The purpose of this review article is to provide an overview of currently identified receptor complexes containing dopamine receptors and of their modulatory action on dopamine-mediated signaling between neurons and between neurons and astrocytes. Pharmacological possibilities offered by targeting receptor complexes in terms of addressing neuropsychiatric disorders associated with altered dopamine signaling will also be briefly discussed.

Different patterns of mast cell distribution in B-cell non-Hodgkin lymphomas.

Tumor growth, progression, and metastatic capability in non-Hodgkin lymphomas (NHLs) are influenced by different component of tumor microenvironment, including inflammatory cells. Among these latter, mast cells play a crucial role. The spatial distribution of mast cells inside the tumor stroma of different types of B-cell NHLs has not yet been investigated. The aim of this study is to analyze the pattern of distribution of mast cells in biopsy samples obtained from three different types of B-cell NHLs by utilizing an image analysis system and a mathematical model to allow a quantitative estimation to characterize their spatial distribution. As concerns the spatial distributions exhibited by mast cells in diffuse large B cell lymphoma (DLBCL), some clustering was detected in both activated B-like (ABC) and germinal center B-like (GBC) groups. In follicular lymphoma (FL), mast cell spatial distribution tends to uniformly fill the tissue space as far as the grade of the pathology increases. Finally, in marginal lymphoma tissue (MALT) lymphoma, mast cells maintain a significantly clustered spatial distribution, suggesting a lower tendency of the cells to fill the tissue space in this pathological condition. Overall, the data of this study confirm that the analysis of the spatial distribution of the tumor cells is of particular significance for the knowledge of the biological processes occurring in tumor stroma and for the development of parameters to characterize the morphologic organization of the cellular patterns in different types of tumors.

Bioinformatics and mathematical modelling in the study of receptor-receptor interactions and receptor oligomerization: focus on adenosine receptors.

The concept of intra-membrane receptor-receptor interactions (RRIs) between different types of G protein-coupled receptors (GPCRs) and evidence for their existence was introduced by Agnati and Fuxe in 1980/81 through the biochemical analysis of the effects of neuropeptides on the binding characteristics of monoamine receptors in membrane preparations from discrete brain regions and functional studies of the interactions between neuropeptides and monoamines in the control of specific functions such as motor control and arterial blood pressure control in animal models. Whether GPCRs can form high-order structures is still a topic of an intense debate. Increasing evidence, however, suggests that the hypothesis of the existence of high-order receptor oligomers is correct. A fundamental consequence of the view describing GPCRs as interacting structures, with the likely formation at the plasma membrane of receptor aggregates of multiple receptors (Receptor Mosaics) is that it is no longer possible to describe signal transduction simply as the result of the binding of the chemical signal to its receptor, but rather as the result of a filtering/integration of chemical signals by the Receptor Mosaics (RMs) and membrane-associated proteins. Thus, in parallel with experimental research, significant efforts were spent in bioinformatics and mathematical modelling. We review here the main approaches that have been used to assess the interaction interfaces allowing the assembly of GPCRs and to shed some light on the integrative functions emerging from the complex behaviour of these RMs. Particular attention was paid to the RMs generated by adenosine A(2A), dopamine D(2), cannabinoid CB(1), and metabotropic glutamate mGlu(5) receptors (A(2A), D(2), CB(1) and mGlu(5), respectively), and a possible approach to model the interplay between the D(2)-A(2A)-CB(1) and D(2)-A(2A)-mGlu(5) trimers is proposed.

Bioinformatics aggregation predictors in the study of protein conformational diseases of the human nervous system.

Conformational protein diseases of the human central nervous system represent a subject that has crucial theoretical and medical implications. They include several important neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's and Creutzfeldt-Jacob's diseases, amyotrophic lateral sclerosis, and the tauopathies. They occur when soluble proteins undergo conformational rearrangements becoming capable of aggregate into ß-sheets conformations leading to the production of insoluble complexes known as amyloid deposits, that accumulate and lead to neurons and glial cells death. Theoretical and experimental evidence indicates that a key role in the conformational changes leading to amyloid formation is played by short sequence stretches within a given protein. Thus, the identification of protein regions potentially involved in aggregate formation and the characterization of their properties are relevant questions in the study of conformational proteins diseases. To address these questions, bioinformatics methods might provide an important contribution, suggesting possible mechanisms of protein aggregation, and focusing and orienting the experimental work. Thus, in the first part of the present review bioinformatics methods specifically attempting to predict aggregation-prone regions in proteins will be briefly described. Furthermore, the results provided by the combined use of some of them to analyze a set of particularly important proteins involved in human degenerative diseases will be discussed.

Spatial Statistics-Based Image Analysis Methods for the Study of Vascular Morphogenesis.

Several studies are available addressing the mechanisms of vascular morphogenesis in order to unravel how cooperative cell behavior can follow from the underlying, genetically regulated behavior of endothelial cells and from cell-to-cell and cell-to-extracellular matrix interactions. From the morphological standpoint several aspects of the process are of interest. They include the way the pattern of vessels fills the available tissue space and how the network grows during the angiogenic process, namely how a main trunk divides into smaller branches, and how branching occurs at different distances from the root point of a vascular tree. A third morphological aspect of interest concerns the spatial relationship between vessels and tissue cells able to secrete factors modulating endothelial cells self-organization, thus influencing vascular rearrangement.In the present chapter image analysis methods allowing for a quantitative characterization of these morphological aspects will be detailed and discussed. They are almost based on concepts derived from the theoretical framework represented by spatial statistics.