55 research outputs found

    Adrenergic and cholinergic innervation of the atrioventricular valves in chinchilla (Chinchilla laniger)

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    The arrangement of autonomic fibres was studied in the cardiac atrioventricular valves of small chinchillas. The dissected valves were stained entirely using the modified histochemical acetylcholine esterase technique (AChE) and the SPG-De la Torre method. Double immunocytochemical staining was also used for the expression of vesicular acetylcholine transporter (VAChT) and dopamine beta hydroxylase (DBH). The study showed the presence of both cholinergic and adrenergic fibres, forming a kind of network on all cusps of both valves. The adrenergic network is always more strongly represented than the cholinergic network. The cholinergic nerve network of the “parietal” part formed mainly the parallel arrangement. As we move towards the free parts of the cusps, the arrangement becomes netted and radiant. The adrenergic fibres formed only the netted arrangement, which was the most dense in the peripheral (parietal) part of the cusps. Some of the fibres in the vicinity of tendinous cords extended as far as the papillary muscles. Double immunocytochemical tests confirmed the presence and distribution of DBH- and VAChT-positive fibres. Some fibres (especially within the tendinous cords) show VAChT and DBH colocalisation

    Four left renal arteries — a rare variant of kidney arterial supply

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    We describe the arterial supply of a human kidney harvested post-mortem from a 75-year-old female volunteer body donor. The kidney was analysed with con- trast-enhanced computed tomography (CT), and corrosion casting was used to reveal the kidney’s angio-architecture. In the left kidney, we observed four renal arteries, each originating directly from the abdominal aorta. Three renal arteries, including the main renal artery, coursed through the renal hilum, and the fourth renal artery reached the lower kidney pole. The supply areas of each of the four renal arteries were analysed with a three-dimensional reconstruction of CT images and with corrosion casting. There were no clear boundaries between the areas supplied by the four renal arteries because their branches overlapped in most kidney segments.

    Anatomical and histological data on the ciliary ganglion in the Egyptian spiny mouse (Acomys cahirinus Desmarest)

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    The morphology and topography of the ciliary ganglion in the Egyptian spiny mouse were studied with use of histochemical and histological techniques. The ciliary ganglion of the Egyptian spiny mouse consisted of between 3 and 4 agglomerations of nerve cells. The largest was situated at the point where the ventral branch of the oculomotor nerve divides into two branches. The next two smaller aggregations were located on the superior and lateral surfaces of the optic nerve where it crossed the oculomotor nerve. From the main agglomerations of neurocytes arose between 3 and 4 intensively stained postganglionic cholinergic fibres. These followed the optic nerve to the eyeball. On the crosssections of these bundles small agglomerations of neurocytes were observed. These decreased in size to only 2 or 3 cells towards the sclera. The ganglionic neurocytes in the largest ganglion varied from 15 to 30 µm in diameter. They were distributed uniformly over the whole surface of the sections. All the ganglia had connective capsules

    Rare morphological variants of the bones: epicondylar processes, metopic suture and Wormian bones in XVIII century skeleton

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    Background: Analysis of the female skeleton from the 18th century revealed a collection of morphological changes. Materials and methods: Anthropological evaluation and dental X-ray techniques allowed the age to be determined at 12–13 years. Results: The distal parts of the both humerus bones had distinct, supracondylar processes of about 5 mm at the medial-lateral surface. The frontal bone had a well-preserved metopic suture along the entire length of the squama. There were also two Wormian bones (Inca bones), asymmetrical mastoid foramen, and only left non-obliterated condylar canal. Conclusions: The skull measurements allowed the cranial index to be determined — 93.5 (brachycephalia) and height-length index — 98.6 (akrocephalus). Moreover, X-ray analysis of incomplete dentition was made

    Free energy barrier for melittin reorientation from a membrane-bound state to a transmembrane state

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    An important step in a phospholipid membrane pore formation by melittin antimicrobial peptide is a reorientation of the peptide from a surface into a transmembrane conformation. In this work we perform umbrella sampling simulations to calculate the potential of mean force (PMF) for the reorientation of melittin from a surface-bound state to a transmembrane state and provide a molecular level insight into understanding peptide and lipid properties that influence the existence of the free energy barrier. The PMFs were calculated for a peptide to lipid (P/L) ratio of 1/128 and 4/128. We observe that the free energy barrier is reduced when the P/L ratio increased. In addition, we study the cooperative effect; specifically we investigate if the barrier is smaller for a second melittin reorientation, given that another neighboring melittin was already in the transmembrane state. We observe that indeed the barrier of the PMF curve is reduced in this case, thus confirming the presence of a cooperative effect

    Membrane Partitioning: “Classical” and “Nonclassical” Hydrophobic Effects

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    The free energy of transfer of nonpolar solutes from water to lipid bilayers is often dominated by a large negative enthalpy rather than the large positive entropy expected from the hydrophobic effect. This common observation has led to the idea that membrane partitioning is driven by the “nonclassical” hydrophobic effect. We examined this phenomenon by characterizing the partitioning of the well-studied peptide melittin using isothermal titration calorimetry (ITC) and circular dichroism (CD). We studied the temperature dependence of the entropic (−TΔS) and enthalpic (ΔH) components of free energy (ΔG) of partitioning of melittin into lipid membranes made of various mixtures of zwitterionic and anionic lipids. We found significant variations of the entropic and enthalpic components with temperature, lipid composition and vesicle size but only small changes in ΔG (entropy–enthalpy compensation). The heat capacity associated with partitioning had a large negative value of about −0.5 kcal mol−1 K−1. This hallmark of the hydrophobic effect was found to be independent of lipid composition. The measured heat capacity values were used to calculate the hydrophobic-effect free energy ΔGhΦ, which we found to dominate melittin partitioning regardless of lipid composition. In the case of anionic membranes, additional free energy comes from coulombic attraction, which is characterized by a small effective peptide charge due to the lack of additivity of hydrophobic and electrostatic interactions in membrane interfaces [Ladokhin and White J Mol Biol 309:543–552, 2001]. Our results suggest that there is no need for a special effect—the nonclassical hydrophobic effect—to describe partitioning into lipid bilayers

    Interaction of melittin with phosphatidylcholine membranes : binding isotherm and lipid head-group conformation

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    The binding of melittin to nonsonicated bilayer membranes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine was studied with an ultracentrifugation assay and with 2H and 31P nuclear magnetic resonance. Melittin binding could best be described by a partition equilibrium with Kp = (2.1 +/- 0.2) X 10(3) M-1, measuring the binding isotherm in the concentration range of 0-100 microM melittin and taking into account electrostatic effects by means of the Gouy-Chapman theory. This partition coefficient is smaller than that deduced for small sonicated vesicles and attests to the tighter lipid packing in the nonsonicated bilayers. Deuterium magnetic resonance revealed a conformational change of the phosphocholine head group upon melittin binding. The quadrupole splittings of the alpha and beta segments of the choline head group varied linearly with the amount of bound melittin but in opposite directions; i.e., the alpha splitting decreased, and the beta splitting increased. This conformational change is not specific to melittin but is a response of the phosphocholine head group to positive membrane surface charges in general. Quantitatively, melittin is one of the most efficient head-group modulators, the efficiency per unit charge comparable to that of charged local anesthetics or hydrophobic ions

    Morphology and immunohistochemical characteristics of the pterygopalatine ganglion in the chinchilla (Chinchilla laniger, Molina)

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    Histological and histochemical investigations revealed that the pterygopalatine ganglion (PPG) in the chinchilla is a structure closely connected with the maxillary nerve. Macro-morphological observations disclosed two different forms of the ganglion: an elongated stripe representing single agglomeration of nerve cells, and a ganglionated plexus comprising smaller aggregations of neurocytes connected with nerve fibres. Immunohistochemistry revealed that nearly 80% of neuronal cell bodies in PPG stained for acetylcholine transferase (CHAT) but only about 50% contained immunoreactivity to vesicular acetylcholine transporter (VACHT). Many neurons (40%) were vasoactive intestinal polypeptide (VIP)-positive. Double-staining demonstrated that approximately 20% of the VIP-immunoreactive neurons were VACHT-negative. Some neurons (10%) in PPG were simultaneously VACHT/nitric oxide synthase (NOS)- or Met-enkephaline (Met-ENK)/CHAT-positive, respectively. A small number of the perikarya stained for somatostatin (SOM) and solitary nerve cell bodies expressed Leu-ENK- and galanin-immunoreactivity. Interestingly about 5-8% of PPG neurons exhibited immunoreactivity to tyrosine hydroxylase (TH). Intraganglionic nerve fibres containing immunoreactivity to VACHT-, VIP- and Met-ENK- were numerous, those stained for calcitonin gene related peptide (CGRP)- and substance P (SP)- were scarce, and single nerve terminals were TH-, GAL-, VIP- and NOS-positive

    Prediction of off-runway takeoff and landing performance.

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    Consumer Attitudes toward Sustainable Development and Risk to Brand Loyalty

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    The present study reveals the importance of understanding how business decisions focused on sustainability can impact companies, due to the risks associated with brand loyalty. The relationship between brand loyalty and consumers’ environmental viewpoint is investigated, including how consumers’ brand loyalty would be impacted after environmental-based expansion decisions are announced. College students from the USA and Romania (N = 92) were asked to voluntarily participate in a survey. The Brand Loyalty Scale (BLS) is used to assess brand loyalty before and after a fictitious expansion announcement was made and the New Ecological Paradigm (NEP) scale is utilized to assess attitudes toward sustainability. A paired samples t-test analysis reveals a significant positive correlation between NEP scores (attitudes toward sustainability) and brand loyalty. No significant differences are found in attitudes toward sustainability regarding region (Romania and USA) or gender. These results indicate that individuals who generally show concern towards the environment will stay loyal to their favorite companies after sustainability is introduced. Results also indicate that the gap regarding region and gender is slowly closing in attitudes toward sustainability; individuals in developing countries are also showing a major concern toward environmental issues. Males indicate just as much concern toward the environment as females, which is confirmed by other findings in previous literature
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