Perfusion Fixation With Glutaraldehyde and Post-Fixation With Osmium Tetroxide for Electron Microscopy

The conductivity of cerebral cortex drops during perfusion with glutaraldehyde in 5 min to about 60% of the original value, to remain unchanged during the subsequent 10-15 min of perfusion. Circulatory arrest causes a similar drop in the tissue conductivity. Perfusion of asphyxiated tissue with glutaraldehyde does not produce additional major changes in the conductivity. Perfusion of the cortex with an osmium tetroxide solution causes an initial drop in conductivity. However, after about 3 min this trend is reversed and the conductivity increases again to close to the pre-perfusion value. Perfusion of asphyxiated cortex with OsO4 causes a marked increase of the conductivity. So does perfusion with an OsO4 solution of tissue previously treated with glutaraldehyde. One interpretation of these impedance changes is that glutaraldehyde perfusion causes, like asphyxiation, a transport of extracellular material into the intracellular compartment and that during OsO4 perfusion an extracellular space is again created. This possibility is supported by electron micrographs made of this material. Cerebral cortex perfused with glutaraldehyde and post-fixed with OsO4 shows electron-transparent dendritic elements and to a lesser extent pre-synaptic terminals, which seem to be swollen. When the cortex is flooded with a salt solution during glutaraldehyde perfusion the dendrites exhibit ballooning in the surface layer of the cortex, suggesting that the fluid on the cortex participates in the swelling. The tissue elements in the glutaraldehyde-perfused and OsO4 post-fixed cortex are separated by narrow extracellular spaces. The latter may have been produced by the OsO4 perfusion as is suggested by a comparison of micrographs prepared by freeze substitution (which tends to preserve the water distribution) of glutaraldehyde-perfused but not post-fixed cortex with micrographs of cortex treated with OsO4 after the glutaraldehyde perfusion. In accordance with the conductivity changes, the former micrographs showed very little extracellular space, and in many places tight junctions, whereas the latter showed clefts between the tissue elements

Packet Relaying Control in Sensing-based Spectrum Sharing Systems

Cognitive relaying has been introduced for opportunistic spectrum access systems by which a secondary node forwards primary packets whenever the primary link faces an outage condition. For spectrum sharing systems, cognitive relaying is parametrized by an interference power constraint level imposed on the transmit power of the secondary user. For sensing-based spectrum sharing, the probability of detection is also involved in packet relaying control. This paper considers the choice of these two parameters so as to maximize the secondary nodes' throughput under certain constraints. The analysis leads to a Markov decision process using dynamic programming approach. The problem is solved using value iteration. Finally, the structural properties of the resulting optimal control are highlighted

Adaptive Modulation in Multi-user Cognitive Radio Networks over Fading Channels

In this paper, the performance of adaptive modulation in multi-user cognitive radio networks over fading channels is analyzed. Multi-user diversity is considered for opportunistic user selection among multiple secondary users. The analysis is obtained for Nakagami-$m$ fading channels. Both adaptive continuous rate and adaptive discrete rate schemes are analysed in opportunistic spectrum access and spectrum sharing. Numerical results are obtained and depicted to quantify the effects of multi-user fading environments on adaptive modulation operating in cognitive radio networks

Strut and Tie Modeling for RC Deep Beams under non-Central Loadings

This work aims at presenting detailed procedures companied by numerical examples for analyzing and designing reinforced concrete deep beams that subjected to non-central loadings based on Strut and Tie method (STM). The subjected loadings were moved from the center of the beam span towards the supports reaching the maximum non-centrality could be achieved (after which the beams became ‘not deep’ from ACI 318M-14 point of view). A total of three deep beams with three different types of loadings were taken into considerations; one concentrated force, two concentrated forces and uniformly distributed load. Every specimen had a cross section of 150  400 mm and a total length of 1000 mm. Generally, it was found that moving load from the span center towards one of the supports leads to worth notable decreases in the beam ultimate capacity. Therefore, in the case of one-concentrated force, the ultimate load capacity decreased by 30.2% when left shear span to effective depth ratio (aL/d) decreased from 1.3 to 0.65. While in the cases of two-concentrated forces or uniformly distributed loading, it was found that changing (aL/d) ratio from 1.02 to 0.37 led to decrease the deep beam ultimate capacity by 30.5%

Spectrophotometric Studies of Some Nitrosonaphthols

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Changes in Extracellular Space of the Mouse Cerebral Cortex During Hydroxyadipaldehyde Fixation and Osmium Tetroxide Post-Fixation

Perfusion of the cerebral cortex of mice with a 4.5 and 12.5% hydroxyadipaldehyde (HAA) solution in a cacodylate buffer caused a biphasic change in the tissue conductivity. After a latency of a fraction of a minute the cortical conductivity dropped markedly, reaching a minimum in 1.5-2 min. Then the conductivity increased again. Electron micrographs (EMs) of material perfused with HAA for 15-20 min and post-fixed with osmium tetroxide showed electron-transparent swollen structures, some of which could be identified as dendritic. The extracellular space consisted of 100-200 Å slits between the tissue elements and larger spaces in bundles of small profiles (unmyelinated axons). Cortex frozen after 2 min perfusion with HAA and subjected to substitution in acetone containing 2 % OsO4 at -85 °C showed swollen (dendritic) structures and a paucity of extracellular material in accordance with the conductivity drop. Often tight junctions between the tissue elements were present. Tissue frozen after 15-20 min of HAA perfusion when the conductivity had increased again yielded EMs which were characterized by an abundance of extracellular space between the small profiles. The mitochondria in the swollen (dendritic) structures were enormously enlarged. Cortex perfused for 15-20 min with HAA, post-fixed with OsO4 and then freeze substituted produced EMs resembling those of tissue fixed in the same way but not subjected to freeze substitution. The examination of the fixation process by freeze substitution demonstrated a sequence of major changes in the fluid distribution of the tissue which precludes any direct relationship between the spaces in the normal and fixed tissue

Chromosome 22 microdeletion in children with syndromic congenital heart disease by fluorescent in situ hybridization (FISH)

Congenital heart diseases (CHDs) are the most common of all birth defects. Congenital heart disease may occur as an isolated malformation or may be part of a syndrome. One of the most common syndromes associated with CHDs is the 22q11.2 microdeletion syndrome, the various conditions associated with del22q11 include DiGeorge syndrome (DGS), velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome (CTAFS), and others. The abnormalities associated with this syndrome include parathyroid hypoplasia, thymic hypoplasia, immune defect, cleft palate, and abnormal facies. The cardiac defects are usually derived from conotruncus. The aim of the study was to detect the prevalence and the most common or frequent clinical manifestations of chromosome 22q11.2 microdeletion among children with syndromic congenital heart disease. The study was conducted on 20 children with syndromic CHD presenting to the Menoufiya University Hospitals, Egypt. Their ages ranged from 10 days to 12 years. Cytogenetic study and fluorescence in situ hybridization (FISH) were performed in the patients. The study revealed that 2 patients were with chromosomal aberrations [one with 46,XY, add (13)(p13) & the other with 47,XX,+13]. In addition, FISH revealed 4 patients (20%) with 22q11.2 microdeletion syndrome. The congenital heart malformations detected in patients with 22q11.2 microdeletion were somewhat unexpected and included VSD, ASD, PDA, and double outlet right ventricle. The most frequent extracardiac features were hypocalcemia, microcephaly, brain atrophy, epicanthus, low set posteriorly rotated ears, micrognathia, and anemia. The extracardiac features were in some cases subtle. It is concluded that 22q11.2 microdeletion is not uncommon and its manifestations are highly variable. This entails that screening for the microdeletion by FISH should be performed in all patients with syndromic CHD especially those with hypocalcemia, microcephaly, brain atrophy, epicanthus, low set ears, posteriorly rotated ears, micrognathia, and anemia. In addition, patients with minor features and those with non-conotruncal heart disease should not be excluded from the screening for 22 microdeletion.Keywords: Chromosome 22 microdeletion; Syndromic congenital heart disease; DiGeorge syndrome; Hypocalcemia; Velocardiofacial syndrom

Conceptualising nature-based solutions: addressing environmental challenges in the city of Amman, Jordan

This article explores the conceptualisation and applicability of nature-based solutions (NBS) in the semi-arid context of Amman, Jordan. Through a Delphi survey, interviews and literature review, it investigates local experts’ views, concluding that NBS are a viable approach, even in context of water scarcity and high urban temperatures. Our results advocate for a paradigm shift towards a balanced relationship between urbanisation and nature, the integration of nature-based thinking into educational systems and continuous development and training for planners and local officers. Cross-sector collaboration, a solid participatory framework, and financial mechanisms for pilot cases are essential for this transformative shift

Derivatographic detection of pig's fat in other animal fats

Egyszerű és gyors módszert írnak le a sertészsír kimutatására más állati zsírokban vagy hidrogénezett növényi olajokhoz keverten. Az eljárásnál nincs szükség előzetes elválasztásra, és alkalmasnak bizonyult a sertészsír jelenlétének kimutatására egyes importált húskonzervekben. Eine einfache und rasche Methode wird zum Nachweis des Schweinefet ts in anderen tierischen Fetten oder in Fettgemischen m it hydrierten Pflanzenöl en eschrieben. Bei der Methode wird keine vorangehende Abtrennung benöti gt, und dieMethode erwies sich als geeignet, in einigen importierten Fleischkons erven die Gegenwart von Schweinefleisch nachwuweisen

Obstructive jaundice secondary to pancreatic head adenocarcinoma in a young teenage boy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Pancreatic adenocarcinoma is extremely rare in childhood. We report a case of metastatic pancreatic adenocarcinoma in a 13-year-old boy, revealed by jaundice.</p> <p>Case presentation</p> <p>A 13-year-old Moroccan boy was admitted with obstructive jaundice to the children's Hospital of Rabat, Department of Pediatric Oncology. Laboratory study results showed a high level of total and conjugated bilirubin. Computerized tomography of the abdomen showed a dilatation of the intra-hepatic and extra-hepatic bile ducts with a tissular heterogeneous tumor of the head of the pancreas and five hepatic lesions. Biopsy of a liver lesion was performed, and a histopathological examination of the sample confirmed the diagnosis of metastatic ductal adenocarcinoma of the pancreas. Our patient underwent a palliative biliary derivation. After that, chemotherapy was administered (5-fluorouracil and epirubicin), however no significant response to treatment was noted and our patient died six months after diagnosis.</p> <p>Conclusion</p> <p>Malignant pancreatic tumors, especially ductal carcinomas, are exceedingly rare in the pediatric age group and their clinical features and treatment usually go unappreciated by most pediatric oncologists and surgeons.</p