Finite element analysis of helicoidal waveguides

The purpose of the paper is to propose an efficient method to compute propagation modes in helicoidal waveguides. An helicoidal system of co-ordinates is introduced to define the structure and to set up the problem. These co-ordinates, albeit non-orthogonal, preserve the translational invariance in a way that allows a two-dimensional finite element model similar to that of classical straight waveguides     

Plasma Metabolomics Profile of “Insulin Sensitive” Male Hypogonadism after Testosterone Replacement Therapy

Male hypogonadism is a disorder characterized by low levels of testosterone, but patients can either show normal insulin (insulin-sensitive (IS)) or over time they can become insulin-resistant (IR). Since the two groups showed different altered metabolisms, testosterone replacement therapy (TRT) could achieve different results. In this paper, we analyzed plasma from 20 IS patients with low testosterone (<8 nmol/L) and HOMAi < 2.5. The samples, pre- and post-treatment with testosterone for 60 days, were analyzed by UHPLC and mass spectrometry. Glycolysis was significantly upregulated, suggesting an improved glucose utilization. Conversely, the pentose phosphate pathway was reduced, while the Krebs cycle was not used. Branched amino acids and carnosine metabolism were positively influenced, while β-oxidation of fatty acids (FFA) was not activated. Cholesterol, HDL, and lipid metabolism did not show any improvements at 60 days but did so later in the experimental period. Finally, both malate and glycerol shuttle were reduced. As a result, both NADH and ATP were significantly lower. Interestingly, a significant production of lactate was observed, which induced the activation of the Cori cycle between the liver and muscles, which became the main source of energy for these patients without involving alanine. Thus, the treatment must be integrated with chemicals which are not restored in order to reactivate energy production.     

Random amplified polymorphic DNA (RAPD) interpretation requires a sensitive method for the detection of amplified DNA

The random amplified polymorphic DNA technique (RAPD) has found wide use in molecular genetics because of its speed and ease of use. For various reasons, with this method the amplified DNA fragments are produced at different concentrations between genotypes and even between polymerase chain reaction (PCR) runs. Since the detection of the multiple amplified fragments is performed routinely by agarose gel, and seldom by acrylamide gel electrophoresis, we have found that by capillary zone electrophoresis (CZE), which is more sensitive and accurate than gel electrophoresis, it is possible to unequivocally detect amplified fragments even at low concentration, avoiding polymorphism misinterpretation. CZE is also useful to make more potentially polymorphic fragments evident per random primer used, with obvious economical benefits.     

Nitric oxide synthase activity in tissues of the blowfly Chrysomya megacephala (Fabricius, 1794).

Although insects lack the adaptive immune response of the mammalians, they manifest effective innate immune responses, which include both cellular and humoral components. Cellular responses are mediated by hemocytes, and humoral responses include the activation of proteolytic cascades that initiate many events, including NO production. In mammals, nitric oxide synthases (NOSs) are also present in the endothelium, the brain, the adrenal glands, and the platelets. Studies on the distribution of NO-producing systems in invertebrates have revealed functional similarities between NOS in this group and vertebrates. We attempted to localize NOS activity in tissues of na?ve (UIL), yeast-injected (YIL), and saline-injected (SIL) larvae of the blowfly Chrysomya megacephala, using the NADPH diaphorase technique. Our findings revealed similar levels of NOS activity in muscle, fat body, Malpighian tubule, gut, and brain, suggesting that NO synthesis may not be involved in the immune response of these larval systems. These results were compared to many studies that recorded the involvement of NO in various physiological functions of insects.     

Histological and immunological reaction of cattle skin to first-instar larvae of Dermatobia hominis

Six cattle that had earlier exposure to Dermatobia hominis were infested experimentally with first-instar larvae of the parasite. Skin biopsies taken at intervals were studied in wax and in plastic sections. The avidin-biotin-peroxidase method was used to detect the presence and localization of host immunoglobulins (Igs) G and M and antigens of first and second instar larvae of Dermatobia hominis. The larvae penetrated actively through the skin and migrated towards the subcutaneous tissues. The great numbers of eosinophils suggest that they are the most important cell in mediating damage to D. hominis larvae. The immunoglobulins bound only to dead or moulting larvae in which access to binding sites may have been altered. This could represent a morphological manifestation of a mechanism that protects larvae from the host immune response. Large amounts of soluble antigens detected along the fistulous tract may be important in the maintenance of this tract by distributing the normal cicatrization process.     

High-performance liquid chromatography-electrospray ionization mass spectrometry using monolithic capillary columns for proteomic studies

The use of tetrahydrofuran/decanol as porogens for the fabrication of micropellicular poly(styrene/divinylbenzene) monoliths enabled the rapid and highly efficient separation of peptides and proteins by reversed-phase high-performance liquid chromatography (RP-HPLC). In contrast to conventional, granular, porous stationary phases, in which the loading capacity is a function of molecular mass, the loadability of the monoliths both for small peptides and large proteins was within the 0.40.9-pmol range for a 60- x 0.2-mm capillary column. Lower limits of detection obtained by measuring UV-absorbance at 214 nm with a 3-nl capillary detection cell were 500 amol for an octapeptide and 200 amol for ribonuclease A. Upon reduction of the concentration of trifluoroacetic acid in the eluent from the commonly used 0.1-0.2 to 0.05%, the separation system was successfully coupled to electrospray ionization mass spectrometry (ESI-MS) at the cost of only a small decrease in separation efficiency. Detection limits for proteins with ESI-MS were in the lower femtomole range. High-quality mass spectra were extracted from the reconstructed ion chromatograms, from which the masses of both peptides and proteins were deduced at a mass accuracy of 50-150 ppm. The applicability of monolithic column technology in proteomics was demonstrated by the mass fingerprinting of tryptic peptides of bovine catalase and human transferrin and by the analysis of membrane proteins related to the photosystem II antenna complex of higher plants.