Opposite patterns of age-associated changes in neurons and glial cells of the thalamus of human brain

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.

Thalamic abnormalities in older adults with remitted early-onset depression using structural magnetic resonance imaging

BACKGROUND

The thalamus is a key diencephalic structure involved in major depressive disorder (MDD). Studies have consistently revealed abnormalities in thalamic volumes in older adults with late-onset depression (LOD), however abnormalities in older adults with early-onset depression (EOD) have not yet been well-studied.

METHODS

Fifty-nine euthymic participants with a history of EOD and fifty-nine matched comparison participants without a lifetime history of depression underwent neuroimaging, medical and neuropsychological assessments. Thalamic volumes were compared between groups. To investigate the previously-proposed right hemispheric (RH) dominance theory of MDD, we explored the bilateral, right and left hemispheric (LH) thalamic volumes. Multiple regression analyses were used to evaluate between-group and within-group effects. Correlational analyses examined associations between group and cognitive performance.

RESULTS

Relative to the comparison group, those with EOD had significantly larger bilateral, LH and RH thalamic volumes. Those with EOD, those who were younger, and those who had fewer years of education demonstrated larger bilateral and LH thalamic volumes. For RH thalamic volumes, those with EOD and those who were younger demonstrated larger RH thalamic volumes. EOD within-group models were also run to assess associations between relevant depression variables. The results showed that only age was significant for bilateral and RH thalamic volumes. For the LH thalamic volumes, the model was not significant. No significant correlations were found between cognitive performance and EOD groups.

CONCLUSION

Older adults with a history of EOD showed significantly larger bilateral, RH and LH thalamic volumes. Further research is needed to delineate potential underlying mechanisms of this change.

SHBG141-161 Domain-Peptide Stimulates GPRC6A-Mediated Response in Leydig and β-Langerhans cell lines

GPRC6A is acknowledged as a major regulator of energy metabolism and male fertility through the action of undercarboxylated osteocalcin (ucOCN), representing a possible therapeutic target. We recently showed that the sex hormone-binding globulin (SHBG) binds to GPRC6A through the likely involvement of the 141-161 domain. To confirm this model, here we investigated the possible binding and agonist activity of SHBG(141-161) domain-peptide (SHBG_141-161) on GPRC6A. The binding of SHBG_141-161 to GPRC6A and downstream dissociation from G_αi(GDP) protein was computationally modelled. SHBG_141-161 was obtained by solid-phase synthesis, characterized by circular dichroism (CD) and the receptor binding was assessed by displacement of ucOCN on HEK-293 cells transfected with GPRC6A gene. Agonist activity of SHBG_141-161 was assessed on Leydig MA-10 and Langerhans β-TC6 cell lines through the GPRC6A-mediated release of testosterone (T) and insulin. SHBG_141-161 was predicted to bind to GPRC6A and to reduce the affinity for G_αi(GDP) at computational level. Conformational properties and binding to GPRC6A of the synthetic SHBG_141-161 were confirmed by CD and displacement experiments. SHBG_141-161 stimulated cell secretion of T and insulin, with dose dependency from 10^-13 to 10^-11M for T release (respectively P = 0,041 10^-13M; P = 0,032 10^-12M; P = 0,008 10^-11M vs basal) and for 10^-12 to 10^-10M for insulin (respectively P = 0,041 10^-12M; P = 0,007 10^-11M; P = 0,047 10^-10M; P = 0,045 vs basal). Blockade with anti GPRC6A IgG abolished the response to SHBG_141-161, suggesting agonist specificity. SHBG_141-161 showed stimulating activity on GPRC6A, representing a template peptide with possible therapeutic use for metabolic and endocrine disorders.

Spatial distribution of mast cells around vessels and glands in human gastric carcinoma

The spatial distribution of mast cells inside the tumor stroma has been little investigated. In this study, we have evaluated tumor mast cells (MCs) distribution in gastric cancer through the analysis of the morphological features of the spatial patterns generated by these cells, including size, shape, and architecture of the cell pattern. The pattern of distribution of tryptase- and chymase-positive MCs around the blood vessels and gastric glands in human gastric adenocarcinoma samples was investigated by immunohistochemical techniques and by introducing a quantitative approach to characterize the spatial distribution of MCs. In human gastric cancer, both chymase-positive MC and vessels exhibited significant deviations from randomness for what it concerns their spatial relationship with gastric parenchyma. As indicated by cell-to-gland distances shorter than expected by chance, in grade II samples a preferential localization of chymase-positive MC near the gastric glands was observed. Interestingly, the same type of spatial association was exhibited by vessels in grade IV samples, where vessel-to-gland distances shorter than expected by chance were observed. These two findings allow to speculate about a sequence of events in which a subpopulation of MC is first recruited around gastric parenchyma to drive the subsequent development of a vascular support to the tissue.

Osteocalcin and Sex Hormone Binding Globulin Compete on a Specific Binding Site of GPRC6A

The undercarboxylated form of osteocalcin (ucOC) regulates male fertility and energy metabolism, acting through the G protein-coupled receptor (GPRC)6A, thus forming a new pancreas-bone-testis axis. Recently, GPRC6A has also been suggested to mediate the nongenomic responses of free testosterone (T). However, these data did not consider the physiological scenario, where circulating T is mainly bound to sex hormone-binding globulin (SHBG) and only a small percentage circulates freely in the blood. Here, by the use of computational modelling, we document the existence of similar structural moieties between ucOC and SHBG that are predicted to bind to GPRC6A at docking analysis. This hypothesis of competition was assessed by binding experiments on human embryonic kidney-293 cells transfected with human GPRC6A gene. Unliganded SHBG specifically bound the membrane of human embryonic kidney-293 cells transfected with GPRC6A and was displaced by ucOC when coincubated at 100-fold molar excess. Furthermore, specific downstream Erk1/2 phosphorylation after stimulation of GPRC6A with ucOC was significantly blunted by 100-fold molar excess of unliganded SHBG. Intriguingly previous incubation with unliganded SHBG, followed by incubation with T, induced Erk1/2 phosphorylation in a dose-dependent manner. Neither binding nor stimulating activities were shown for SHBG saturated with T. Experiments on mutation constructs of GPRC6A strengthened the hypothesis of a common binding site of ucOC and SHBG. Given the role of GPRC6A on energy metabolism, these data agree with epidemiological association between SHBG levels and insulin sensitivity, suggest GPRC6A as a likely SHBG receptor, and add bases for the possible regulation of androgen activity in a nonsteroidal manner.

The Infrapatellar Adipose Body: A Histotopographic Study

The infrapatellar fat pad (IFP) can be regarded as a peculiar form of fibro-adipose tissue localized close to the synovial membrane and articular cartilage. The aims of the present study were to analyze the microscopic anatomy of the IFP through histological and ultrastructural methods, comparing it with that of the subcutaneous tissue of the abdomen and of the knee. Ten specimens of IFP were sampled from bodies of the Donation Program of the University of Padua without a history of osteoarthritis. The IFP consisted of white adipose tissue, of lobular type, with lobules delimited by thin connective septa. The IFP lobule areas were smaller (p < 0.05) and the interlobular septa were thicker (p > 0.05) than those of subcutaneous tissues of the abdomen, whereas the IFP lobule areas were larger (p < 0.05) and the interlobular septa were thinner than those of the subcutaneous tissue of the knee (p < 0.05). The IFP adipocytes present a mean area of 3,708 ± 976 µm2 with a large intercellular space, whereas the mean area of the abdominal tissues was greater (6,082 ± 628 µm2; p < 0.05). At scanning electron microscopy the IFP adipocytes were covered by thick fibrillary sheaths, creating a basket around the adipocytes. The structural characteristics of the IFP (lobular aspect of the adipose tissue, thickness of the septa with scarce elastic fibers) could act as a plastic portion aimed at the absorption of pressure variation during knee articular activity. The extensive distribution of nerves suggests a possible role of the IFP as a mechanoreceptor, corresponding to a tridimensional connective mesh working in the proprioceptive regulation of the activity of the knee joint.

Aneurysm permeability following coil embolization: packing density and coil distribution

Background

Rates of durable aneurysm occlusion following coil embolization vary widely, and a better understanding of coil mass mechanics is desired. The goal of this study is to evaluate the impact of packing density and coil uniformity on aneurysm permeability.

Methods

Aneurysm models were coiled using either Guglielmi detachable coils or Target coils. The permeability was assessed by taking the ratio of microspheres passing through the coil mass to those in the working fluid. Aneurysms containing coil masses were sectioned for image analysis to determine surface area fraction and coil uniformity.

Results

All aneurysms were coiled to a packing density of at least 27%. Packing density, surface area fraction of the dome and neck, and uniformity of the dome were significantly correlated (p<0.05). Hence, multivariate principal components-based partial least squares regression models were used to predict permeability. Similar loading vectors were obtained for packing and uniformity measures. Coil mass permeability was modeled better with the inclusion of packing and uniformity measures of the dome (r²=0.73) than with packing density alone (r²=0.45). The analysis indicates the importance of including a uniformity measure for coil distribution in the dome along with packing measures.

Conclusions

A densely packed aneurysm with a high degree of coil mass uniformity will reduce permeability.

Neuroregeneration and dementia: new treatment options

In the last years, physiological aging became a general concept that includes all the changes that occur in organism with old age. It is obvious now, that in developing and developed countries, new health problems concerning older population appear. One of these major concerns is probably dementia. Sooner or later, all forms of dementia lead to learning deficit, memory loss, low attention span, impairment of speech and poor problem solving skills. Normal ageing is a physiological process that also involves a lot of neurological disorders with the same type of symptoms and effects that many researchers are trying to minimize in demented patients. In this review we try to highlight some of the newest aspects of therapeutic strategies that can improve natural neuroregeneration.

Epo is involved in angiogenesis in human glioma

In this study, the extent of angiogenesis, evaluated as microvascular density, and the immunoreactivity of tumor cells to erythropoietin (Epo) and of endothelial cells to Epo receptor (EpoR) have been correlated in human glioma specimens, and the effect of anti-Epo antibody on glioma-induced angiogenesis in vivo in the chick embryo chorioallantoic membrane (CAM) has been investigated. Results show that: (1) Epo/EpoR expression correlates with angiogenesis, (2) in the CAM assay, tumor bioptic specimens induce a strong angiogenic response, comparable to that induced by VEGF, and (3) an anti-Epo antibody co-administered with tumor bioptic specimens significantly inhibits the angiogenic response. These findings suggest the presence of a loop in the Epo/EpoR system, i.e. Epo is secreted by glioma tumor cells and it affects glioma vascular endothelial cells via its receptor and promotes angiogenesis in a paracrine manner. Moreover, as demonstrated by in vivo experiments, Epo is responsible for the strong angiogenic response induced by human glioma bioptic specimens, because an anti-Epo antibody is able to significantly inhibit this response.

Mast cells and angiogenesis in gastric carcinoma

Previous studies have shown that increased vascularity is associated with haematogenous metastasis and poor prognosis in gastric cancer. The role of mast cells in gastric cancer angiogenesis has not been clarified completely. In this study, we correlated microvascular density and tryptase- and chymase-positive mast cells with histopathological type in gastric cancer. Specimens of primary gastric adenocarcinomas obtained from 30 patients who had undergone curative gastrectomy were investigated immunohistochemically by using anti-CD31 antibody to stain endothelial cells and anti-tryptase and anti-chymase antibodies to stain mast cells. The results showed that stage IV gastric carcinoma has a higher degree of vascularization than other stages and that both tryptase- and chymase-positive mast cells increase in parallel with malignancy grade even if the density of chymase-positive mast cells was significantly lower than the density of tryptase-positive mast cells and is highly correlated with the extent of angiogenesis. This study has demonstrated that mast cell density correlates with angiogenesis and progression of patients with gastric carcinoma. Understanding the mechanisms of gastric cancer angiogenesis provides a basis for a rational approach to the development of an antiangiogenic therapy in patients with this malignancy.

Intussusceptive microvascular growth in human glioma

Intussusceptive microvascular growth (IMG), which occurs by splitting of the existing vasculature by transluminal pillars or transendothelial bridges, has been demonstrated in several tumors such as colon and mammary carcinomas, melanoma and B-cell non-Hodgkin's lymphomas. In this study, we have correlated in human glioma the extent of angiogenesis, evaluated as microvascular density, the immunoreactivity of tumor cells to vascular endothelial growth factor (VEGF), vessel diameter and IMG to the tumor stage. Results demonstrate for the first time a relationship in human glioma progression between angiogenesis, VEGF immunoreactivity of tumor cells, vessel diameter and the number of connections of intraluminal tissue folds with the opposite vascular wall, expression of IMG and suggest that IMG could be a mechanism of compensatory vascular growth occurring in human glioma. The advantages are that (1) blood vessels are generated more rapidly; (2) it is energetically and metabolically more economic; (3) the capillaries thereby formed are less leaky.

Tumoral mast cells exhibit a common spatial distribution

Mast cells (MCs) accumulate in the stroma surrounding tumors and take part in the inflammatory reaction occurring at the margin of the neoplasia. Moreover, MC secretes angiogenic cytokines and matrix metalloproteinases. The aim of this study was to investigate the pattern of distribution of MCs in biopsy samples obtained from four different human tumors, utilizing an image analysis system and a mathematical model to make a quantitative approach to characterizing their spatial distribution. Results showed a similar spatial arrangement of MCs in all the neoplastic tissues examined, despite histological and/or pathologic differences. In all these tissues MCs demonstrated a virtually random spatial distribution, albeit with varying densities. These results suggest that MC-MC interactions could play a minor role in the formation of the MC pattern in neoplastic tissues. The random distribution of the cells in the tissues could be accounted for by a random walk-migration under the influence of cell-matrix interactions or chemotactic fields potentially generated by tumor or endothelial cells.

Generation of a alpha-synuclein-based rat model of Parkinson's disease

Two missense mutations (A30P and A53T) in the gene for alpha-synuclein (alpha-syn) cause familial Parkinson's disease (PD) in a small cohort. There is increasing evidence to propose that abnormal metabolism and accumulation of alpha-syn in dopaminergic neurons play a role in the development of familial as well as sporadic PD. The complexity of the mechanisms underlying alpha-syn-induced neurotoxicity, however, has made difficult the development of animal models that faithfully reproduce human PD pathology. We now describe and characterize such a model, which is based on the stereotaxic injection into rat right substantia nigra pars compacta of the A30P mutated form of alpha-syn fused to a protein transduction domain (TAT). The TAT sequence allows diffusion of the fusion protein across the neuronal plasma membrane and results in a localized dopaminergic loss. Dopaminergic cell loss was evaluated both by tyrosine hydroxylase immunohistochemistry and by HPLC analysis of dopamine and its catabolite 3,4 dihydroxyphenylacetic acid. Infusion of TAT-alpha-synA30P induced a significant 26% loss in dopaminergic neurons. This dopaminergic loss was accompanied by a time-dependent impairment in motor function, evaluated utilizing the rotarod and footprint tests. In comparison to chemical neurotoxin-based (e.g. 6-hyroxydopamine, MPTP) animal models of PD, the alpha-syn-based PD animal model offers the advantage of mimicking the early stages and slow development of the human disease and should prove valuable in assessing specific aspects of PD pathogenesis in vivo and in developing new therapeutic strategies.