Search

Aluminum (Al) is used in everyday life and present in food drugs, packaging, industry, and agriculture. Although it is the most common metal in the Earth crust, a correlation has been demonstrated between its presence and various pathologies, even serious ones, especially of a neurological type. However, there is a histological gap regarding the role Al can have in contact with the covering and secreting epithelia. The alterations of the ventral and dorsal foot mucocytes and their secretions of the snail Eobania vermiculata caused by Al were investigated in situ by histochemical and lectin‐histochemical techniques. Administration to different experimental groups took place for 3 and 9 days with 50 and 200 μM of AlCl3. Several types of mucocytes were detected with a prevalent secretion of acid glycans in the foot of E. vermiculata. Sulfated glycans prevail in the dorsal region, with one type showing only fucosylated residues and another also having galactosaminylated and glycosaminylated residues. Carboxylated glycans prevail in the ventral region, with presence of galactosaminylated, glycosaminylated, and fucosylated residuals in both cells. Snails treated presented a general decrease of mucin amount in the secreting cells and affected the mucus composition. These changes could alter the rheological and functional properties of the mucus with possible implications for the health of the treated animals. Research Highlights: Snails were fed with Al‐contaminated lettuce at different concentrations.In the foot mucocytes produced mucus with prevailing acidic glycans.In the treated resulted a reduction in the amount of mucus and an alteration of glycan composition. [ABSTRACT FROM AUTHOR]

Aquaporins (AQPs) are important for water transport in the gastrointestinal tract. Changes in their expression and/or localization could cause in disorders and be used as therapeutic targets. Aquaporin‐4 (AQP4) is expressed predominantly on the basolateral membrane of the parietal cells in the corpus of the murine gastric glands. Although the secretion of gastric juice is not affected in AQP4‐deficient knockout, we evaluated by light microscopy whether the lack of AQP4 affects the glycopatterns of secreting gastric cells. Wild type (WT) and AQP4‐deficient knockout mice (KO) were fed a standard diet ad libitum before sacrifice. Segments of stomach corpus were collected, fixed in buffered formalin, and embedded in paraffin wax. Sections, 5‐μm thick, were analyzed by histochemical methods (Periodic acid‐Schiff, Alcian Blue pH 2.5), and binding of lectins specific to GalNAc (SBA, DBA), Gal (PNA) GlcNAc (WGA, GSAII) mannose and/or glucose (ConA), and fucose (UEA‐I, AAA, LTA). Immunohistochemical methods such as anti‐Muc6 for neck cells and anti‐ β‐ H+/K+‐ATPase for parietal cells were also performed. Compared to WT mice, in the mucous cells of KO lower amounts of glycans with galactosyl/galactosaminylated, glycosyl/glycosaminylated, and fucosylated residues were observed; lower fucosylation resulted also in the parietal cells. The observed differences of KO in respect to WT could lead to severer pathological conditions. Research Highlights: Glycopatterns in gastric glands were compared between wild type (WT) and AQP4‐deficient knockout (KO) mice by histochemical and lectin‐binding methods.In the mucous cells of KO lower amounts of glycans with galactosyl/galactosaminylated, glycosyl/glycosaminylated and fucosylated residues were observed.In the parietal cells lower fucosylation also resulted.AQP4‐deficiency affects glycosylation and could result in altered functionality and pathological conditions. [ABSTRACT FROM AUTHOR]

The glycopatterns of the glycans secreted by the mucosa of stomach and duodenal ampulla of the striped dolphin, Stenella coeruleoalba were studied by histochemical (Periodic acid‐Schiff, Alcian Blue pH 2.5, High Iron Diamine) and lectin‐binding (SBA, DBA, PNA, WGA, MAA‐II, SNA, ConA, UEA‐I, AAA, LTA) techniques. The stomach can be divided into four compartments: main stomach, two connecting chambers and pylorus. The pylorus is followed by the duodenal ampulla. Mucins are secreted by surface cells and intramucosal glands specific for each compartment. In the main stomach glands, neck cells were weakly sulphated, with prevailing glycosaminylated, glycosylated/mannosylated, and fucosylated residuals. Parietal and chief cells in general were scarcely reactive. In the connecting chambers glands, there were high levels of sulphation, glycosaminylation, glycosylation/mannosylation, and fucosylation, the latter with more complex patterns than those observed in the main stomach glands. In the pyloric glands sulphated, glycosaminylated and fucosylated residuals decreased, whereas the opposite was observed for galactosyl/galactosaminylated residuals. Glycosylation patterns in the glands of the duodenal ampulla differed from those of the pyloric ones, with similar levels of sulphation, lower levels of galactosyl/galactosaminylation and glycosaminylation, and higher level of fucosylation. The results are compared with those available in literature. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a technique for the efficient design of bandpass waveguide microwave filters using a segmentation technique applied to an equivalent circuit. The technique is based on first developing an equivalent circuit that synthesizes the desired transfer function. Then, the different parts of the real physical structure are optimized by segmenting this equivalent circuit. The technique was originally developed for in‐line filters, and the main contribution of this paper is in the combination of this technique with the coupling matrix formalism. In this way, we adapt for the first time this design strategy to the design of complex coupling topologies, beyond the in‐line configuration. As an example, a complex sixth‐order dual‐mode filter, implemented in all‐inductive waveguide technology, is designed using the new coupling matrix segmentation technique, showing the effectiveness of the presented theory. A prototype of the filter has been manufactured, and the accuracy of the design technique is verified by measurements on the real prototype. [ABSTRACT FROM AUTHOR]

In this paper, the design of a novel planar narrowband microstrip filter is presented. The structure is designed and manufactured in microstrip technology, and it is formed by set of pairs of resonators of different lengths. The length of one resonator in each pair is adjusted so that a suitable odd resonance is tuned to the center frequency of the filter. The length of the other resonator is adjusted so that the next even resonance is tuned again to the center frequency of the filter. The different path of the signal in each resonator produces a cancellation of energy at a given frequency, therefore implementing a transmission zero in the insertion-loss response of the filter. First, this paper presents a design example of a single set of resonators (basic unit cell) working at the fifth and sixth resonances. Then, two basic unit cells working at the first and second resonances are first optimized, and then they are cascaded to show how higher-order filter responses can be implemented. The measured results confirm the theoretical predictions, and validate the new structures for high-selectivity applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 450–455, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20499 [ABSTRACT FROM AUTHOR]

An alternative configuration for an infinite coaxially end-fed waveguide phased-array antenna is explored. In the proposed configuration, the integration of the end-fed launcher and the output waveguide, rather than the waveguide in itself, acts as a basic radiator. This allows the design of more compact antenna elements. In order to analyze and optimize the structure, an accurate full-wave simulation tool based on the multimode admittance matrix representation is developed. Results are validated against state-of-the-art commercial CAD software. Numerical simulations involving singly and doubly tuned configurations are presented and discussed to illustrate the potential convenience of the proposed configuration and of the CAD tool developed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 276–281, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10437 [ABSTRACT FROM AUTHOR]

This paper describes a number of broadside-coupled microstrip structures and their use for the implementation of high-selectivity multilayered filters. The broadside configuration allows for the introduction of cross couplings between nonadjacent resonators. The cross couplings can then be used to implement transmission zeros that can significantly increase the selectivity of the filters. Furthermore, the investigation shows that the amount of coupling can be considerably increased if the resonators are broadside coupled, thus easily allowing the implementation of broadband filters. Measured results are shown to agree with predictions, thereby fully validating the new structures described. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 295–302, 2001. [ABSTRACT FROM AUTHOR]

In this article we present two contributions to the study of coaxial waveguide structures. First, we present an efficient and accurate technique to evaluate the modes in the coaxial waveguides; second, we analyze junctions involving coaxial and circular waveguides using the multimode equivalent network representation. Numerical and experimental results are presented, showing good agreement. [ABSTRACT FROM AUTHOR]

Admittance parameters are widely employed to characterize the electromagnetic behavior of arbitrary planar waveguide junctions. Even though strong efforts have been devoted to the development of simple and efficient procedures for evaluating such parameters, it is still very important to further reduce the computation time required when analyzing waveguide systems as they become more complex. This article describes a simple and very fast procedure for computing the admittance parameters of planar waveguide junctions. The key feature of this procedure is that the frequency dependence of the admittance parameters is extracted from all infinite sums. As a result, only a few terms need to be evaluated at each frequency point thereby substantially reducing the computational effort. [ABSTRACT FROM AUTHOR]

Low-loss performance is one of the main drivers in the design of microwave filters and diplexers. In this paper, we propose a simple, low-cost solution to this problem. Measured responses of specific designs are also included, indicating that the solution proposed is indeed practical and cost effective. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 7–9, 2000. [ABSTRACT FROM AUTHOR]