Light microscopic immunocytochemical identification of leucine enkephalin

Leucine-enkephalin is a potent and naturally-occurring opioid peptide which serves to inhibit other neurotransmitters involved with pain perception, thereby reducing its emotional and physical impact. Nevertheless, there is little data in the literature concerning leucine-enkephalin-immunoreactivity (Leu-enk-ir) in the human claustrum. The objectives of this study were to confirm the existence of leucine-enkephalin immunoreactive neurons and fibers in the human claustrum. Light microscopy was used to describe their morphology and distribution. Samples of claustrum were obtained from the brains of two females (39 and 48 years of age) and two males (27 and 42 years of age). The brains did not show any overt signs of pathology or trauma. Immunoreactivity to Leuenk was assessed via the Avidin-Biotin Complex Method. Light-microscopic analysis confirmed the presence of Leu-enk-ir neurons and fibres in all areas of the human claustrum. The cell bodies varied in shape and size, and were divided into three groups: small, medium and large. The density of immunostaining varied both within and between the cell types, with some neurons, staining more darkly or lightly than others. The large and medium sized cells most likely correspond to claustrocortical projection neurons while the small-sized cells appear to be inhibitory interneurons. It is our hope that these results will be contributed to a better understanding the functions of claustrum, in both health and disease, given its relationship with the development of autism, schizophrenia, Alzheimer disease, Parkinson disease and Huntington disease

Visualizing Individual Nitrogen Dopants in Monolayer Graphene

In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We used scanning tunneling microscopy (STM), Raman spectroscopy, x-ray spectroscopy, and first principles calculations to characterize individual nitrogen dopants in monolayer graphene grown on a copper substrate. Individual nitrogen atoms were incorporated as graphitic dopants, and a fraction of the extra electron on each nitrogen atom was delocalized into the graphene lattice. The electronic structure of nitrogen-doped graphene was strongly modified only within a few lattice spacings of the site of the nitrogen dopant. These findings show that chemical doping is a promising route to achieving high-quality graphene films with a large carrier concentration.Comment: Science 201

Heat-Induced Structural Changes Affect OVA-Antigen Processing and Reduce Allergic Response in Mouse Model of Food Allergy

BACKGROUND AND AIMS: The egg protein ovalbumin (OVA) belongs to six most frequent food allergens. We investigated how thermal processing influences its ability to induce allergic symptoms and immune responses in mouse model of food allergy. METHODOLOGY/PRINCIPAL FINDINGS: Effect of increased temperature (70°C and 95°C) on OVA secondary structure was characterized by circular dichroism and by the kinetics of pepsin digestion with subsequent HPLC. BALB/c mice were sensitized intraperitoneally and challenged with repeated gavages of OVA or OVA heated to 70°C (h-OVA). Levels of allergen-specific serum antibodies were determined by ELISA (IgA and IgGs) or by β-hexosaminidase release test (IgE). Specific activities of digestive enzymes were determined in brush border membrane vesicles of jejunal enterocytes. Cytokine production and changes in regulatory T cells in mesenteric lymph nodes and spleen were assessed by ELISA and FACS. Heating of OVA to 70°C caused mild irreversible changes in secondary structure compared to boiling to 95°C (b-OVA), but both OVA treatments led to markedly different digestion kinetics and Tregs induction ability in vitro, compared to native OVA. Heating of OVA significantly decreased clinical symptoms (allergic diarrhea) and immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, h-OVA induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native OVA. On the other hand h-OVA stimulated higher IgG2a in sera and IFN-γ secretion by splenocytes. CONCLUSIONS: Minor irreversible changes in OVA secondary structure caused by thermal processing changes both its digestion and antigenic epitopes formation, which leads to activation of different T cell subpopulations, induces shift towards Th1 response and ultimately reduces its allergenicity

Quantum criticality in ferroelectrics

Materials tuned to the neighbourhood of a zero temperature phase transition often show the emergence of novel quantum phenomena. Much of the effort to study these new effects, like the breakdown of the conventional Fermi-liquid theory of metals has been focused in narrow band electronic systems. Ferroelectric crystals provide a very different type of quantum criticality that arises purely from the crystalline lattice. In many cases the ferroelectric phase can be tuned to absolute zero using hydrostatic pressure or chemical or isotopic substitution. Close to such a zero temperature phase transition, the dielectric constant and other quantities change into radically unconventional forms due to the quantum fluctuations of the electrical polarization. The simplest ferroelectrics may form a text-book paradigm of quantum criticality in the solid-state as the difficulties found in metals due to a high density of gapless excitations on the Fermi surface are avoided. We present low temperature high precision data demonstrating these effects in pure single crystals of SrTiO3 and KTaO3. We outline a model for describing the physics of ferroelectrics close to quantum criticality and highlight the expected 1/T2 dependence of the dielectric constant measured over a wide temperature range at low temperatures. In the neighbourhood of the quantum critical point we report the emergence of a small frequency independent peak in the dielectric constant at approximately 2K in SrTiO3 and 3K in KTaO3 believed to arise from coupling to acoustic phonons. Looking ahead, we suggest that in ferroelectric materials supporting mobile charge carriers, quantum paraelectric fluctuations may mediate new effective electron-electron interactions giving rise to a number of possible states such as superconductivity.Comment: 10 pages, 4 figure

Relationship of suicide rates with climate and economic variables in Europe during 2000-2012

The derived models explained 62.4 % of the variability of male suicidal rates. Economic variables alone explained 26.9 % and climate variables 37.6 %. For females, the respective figures were 41.7, 11.5 and 28.1 %. Male suicides correlated with high unemployment rate in the frame of high growth rate and high inflation and low GDP per capita, while female suicides correlated negatively with inflation. Both male and female suicides correlated with low temperature. Data from 29 European countries covering the years 2000-2012 and concerning male and female standardized suicidal rates (according to WHO), economic variables (according World Bank) and climate variables were gathered. The statistical analysis included cluster and principal component analysis and categorical regression. It is well known that suicidal rates vary considerably among European countries and the reasons for this are unknown, although several theories have been proposed. The effect of economic variables has been extensively studied but not that of climate. The current study reports that the climatic effect (cold climate) is stronger than the economic one, but both are present. It seems that in Europe suicidality follows the climate/temperature cline which interestingly is not from south to north but from south to north-east. This raises concerns that climate change could lead to an increase in suicide rates. The current study is essentially the first successful attempt to explain the differences across countries in Europe; however, it is an observational analysis based on aggregate data and thus there is a lack of control for confounders. RESULTS METHODS BACKGROUND DISCUSSIO

A comparative light-microscopic morphological study of the postnatal changes in the myocardium of the left and right ventricles in rat

According to literature data, age-related remodelling of the myocardium is related to the development of hypertrophy of the cardiomyocytes and interstitial fibrosis. In the present study, we observed accumulation of collagen in the walls of the vessels, interstitium and perivascular zones in Wistar rats from various age groups. Normally, the bundles of cardiomyocytes and the separate cells are surrounded by thin layers of peri- and endomysium. In the aging myocardium, hypertrophy of cardiomyocytes, transformation of fibroblasts into myofibroblasts and accumulation of extracellular matrix proteins in the interstitium are observed. Histological analyses of aging rat hearts show progressive loss of cardiomyocytes due to necrosis and apoptosis. Thus, preserved cardiac muscle cells undergo a process of compensatory hypertrophy. In our study, we investigated postnatal changes in the myocardium of 15 adult male Wistar rats, distributed in the following age groups: 2 weeks, 1, 3, 6 and 12 months old. We used routine haematoxylin and eosin staining and Mallory`s trichrome stain in order to analyse morphological changes in the aging myocardium in the wall of the left and right ventricle, as well as changes undergone by cardiomyocytes. In conclusion, it can be stated that by aging, heart morphology becomes impaired at organ level, as well as at individual cardiomyocyte level. Aging of myocardium is a dynamic process, characterized by hypertrophy of cardiomyocytes, reduced capillary density and increased deposition of collagen. Considering the functional dissimilarities between the left and right ventricle (a more pronounced effect of the afterload on the left ventricle), processes in the left ventricle follow a more dynamic pattern and reactive fibrosis occurs earlier. Changes in the right ventricle occur at a relatively smooth pace

Quantitative characteristics of the myocardium and the cardiomyocytes during different stages of the postnatal development in Wistar rats

Until recently there was a consensus that the growth of the heart during the foetal and postnatal development of the rat is primarily due to hyperplasia of the cardiomyocytes but at a certain moment during the early postnatal development of the heart, cardiomyocyte hyperplasia ceases and during the late postnatal period, heart growth occurs due to hypertrophy of the cardiac muscle cells. For this reason, in healthy rats, no significant changes in the number and size of cardiomyocytes are observed. The mean size of the cardiomyocytes increases in correlation with body growth during the postnatal development and these cells also possess the ability for additional hypertrophy in response to increased workload. While studying cell size, most authors measure the diameter of the cells in transverse histological slides by adopting a cylindrical model of the cell. The diameter is measured either directly in the individual cells or is determined indirectly.In the present study, the quantitative data on the morphology of the free wall of the left and right ventricle in Wistar rats have been obtained during the analysis of the hearts of 15 male rats, divided into five groups: two-week-old; one-month-old; three-month-old; six-month-old; twelve-month-old. For morphometric analysis we used five slides of the heart of each animal by randomly selecting zones in the material where there were no massive tears. The morphometric characteristics are presented and organized through schemes and diagrams, demonstrating the dynamics in the following quantitative indices: thickness of the free wall of the left and right ventricle (μm), transverse section of the cardiomyocytes (μm2) cardiomyocytic density (number of cells/mm2). The changes observed in these indices reflect a tendency for age-related hypertrophy. They are more dynamic and start earlier in the left ventricle and occur in a significantly smoother pattern in the right ventricle