The positional distributions of fatty acids in the triacylglycerols and phosphatidylcholines of the intestinal and popliteal lymph and plasma of sheep

As part of a study of the contribution of the intestinal lymph lipoproteins and their lipid constituents to the plasma lipids in sheep, the positional distributions of the fatty acids in the triacyl-sn-glycerols and phosphatidylcholines in very low density/low density lipoprotein and high-density lipoprotein fractions were determined by stereospecific analysis procedures. The triacyl-sn-glycerols of these lipoprotein fractions in intestinal lymph did not differ appreciably in structure and resembled the plasma triacyl-sn-glycerols in the composition of positionsn-2 especially. However, there were appreciable amounts of the essential fatty acid, linoleic acid, in positionssn-1 andsn-3 of the triacylglycerols in lymph but not in plasma. This result is discussed in terms of the metabolism of the triacylglycerols of lymph after they enter the plasma as part of a mechanism for the conservation of essential fatty acids in ruminants. No differences of metabolic note were observed in the structures of the phosphatidylcholines between lipoprotein fractions and among tissues.     

Feasibility of manual teach-and-replay and continuous impedance shaping for robotic locomotor training following spinal cord injury

Robotic gait training is an emerging technique for retraining walking ability following spinal cord injury (SCI). A key challenge in this training is determining an appropriate stepping trajectory and level of assistance for each patient, since patients have a wide range of sizes and impairment levels. Here, we demonstrate how a lightweight yet powerful robot can record subject-specific, trainer-induced leg trajectories during manually assisted stepping, then immediately replay those trajectories. Replay of the subject-specific trajectories reduced the effort required by the trainer during manual assistance, yet still generated similar patterns of muscle activation for six subjects with a chronic SCI. We also demonstrate how the impedance of the robot can be adjusted on a step-by-step basis with an error-based, learning law. This impedance-shaping algorithm adapted the robot's impedance so that the robot assisted only in the regions of the step trajectory where the subject consistently exhibited errors. The result was that the subjects stepped with greater variability, while still maintaining a physiologic gait pattern. These results are further steps toward tailoring robotic gait training to the needs of individual patients.     

Exodontia‐induced muscular hypofunction by itself or associated to chronic stress impairs masseter muscle morphology and its mitochondrial function

Stress is associated with orofacial pain sensitivity and is qualified as a temporomandibular disorder risk factor. During stressful periods, painful thresholds of masticatory muscles in individuals suffering muscle facial pain are significantly lower than in controls, but the exact physiologic mechanism underlying this relation remains unclear. Our hypothesis is that chronic unpredictable stress and masticatory hypofunction induce morphologic and metabolic masseter muscle changes in rats. For test this hypothesis, adult Wistar rats were submitted to chronic unpredictable stress and/or exodontia of left molars and the left masseter muscle was removed for analysis. The parameters evaluated included ultrastructure, oxidative level, metabolism activity and morphological analysis in this muscle. Our data show by histological analysis, that stress and exodontia promoted a variation on diameters and also angled contours in masseter fibers. The masticatory hypofunction increased oxidative metabolism as well as decreased reactive species of oxygen in masseter muscle. The ultrastructural analysis of muscle fibers showed disruption of the sarcoplasmic reticulum cisterns in certain regions of the fiber in stress group, and the disappearance of the sarcoplasmic reticulum membrane in group with association of stress and exodontia. Our findings clarify mechanisms by which chronic stress and masticatory hypofunction might be involved in the pathophysiology of muscular dysfunctions. Masticatory hypofunction influenced oxidative stress and induced oxidative metabolism on masseter muscle, as well as altered its fiber morphology. Chronic stress presented malefic effect on masseter morphology at micro and ultra structurally. When both stimuli were applied, there were atrophic fibers and a complete mitochondrial derangement.     

The variation of triglyceride structure with fatty acid composition in pig adipose tissue

Forty-five triglyceride samples with a wide range of fatty acid compositions were selected from a large number of pig adipose tissue samples (inner and outer back fats and perenephric fat) available from nutritional experiments. These samples were subjected to stereospecific analysis to determine the changes occurring in the positional distribution of the component fatty acids. The oleic acid content of the triglycerides was taken as the standard of comparison and as this increased, the proportions of the other unsaturated fatty acids also increased in a linear manner and the concentrations of the saturated components decreased proportionately. In position 1, the palmitic acid concentration remained constant while the stearic acid concentration decreased linearly and the concentrations of the unsaturated fatty acids increased. In position 2 the stearic acid concentration remained almost constant while the palmitic acid concentration decreased linearly in response to increases in the concentrations of the unsaturated acids. The least change occurred in position 3 where there were slight decreases in the concentrations of saturated acids as the concentrations of unsaturated acids increased. The precise quantitative relationships depended on the tissue examined. Constant proportions of the available myristic and palmitoleic acids were found in all three positions and constant proportions of the available stearic and oleic acids were found in position 1. These results are discussed in relation to possible pathways of triglyceride biosynthesis in pig adipose tissues.     

Arachidonic, eicosapentaenoic, and biosynthetically related fatty acids in the seed lipids from a primitive gymnosperm, Agathis robusta

The fatty acid composition of the seeds from Agathis robusta, an Australian gymnosperm (Araucariaceae), was determined by a combination of chromatographic and spectrometric techniques. These enabled the identification of small amounts of arachidonic (5,8,11,14–20∶4) and eicosapentaenoic (5,8,11,14,17–20∶5) acid for the first time in the seed oil of a higher plant. They were apparently derived from γ-linolenic (6,9,12–18∶3) and stearidonic (6,9,12,15–18∶4) acids, which were also present, via chain elongation and desaturation, together with other expected biosynthetic intermediates [bis-homo-γ-linolenic (8,11,14–20∶3) and bishomo-stearidonic (8,11,14,17–20∶4) acids]. Also present were a number of C₂₀ fatty acids, known to occur in most gymnosperm families, i.e., 5,11–20∶2, 11,14–20∶2 (bishomo-linoleic), 5,11,14–20∶3 (sciadonic), 11,14,17–20∶3 (bishomo-α-linolenic), and 5,11,14,17–20∶4 (juniperonic) acids. In contrast to most other gymnosperm seed lipids analyzed so far, A. robusta seed lipids did not contain C₁₈ Δ5-desaturated acids [i.e., 5,9–18∶2 (taxoleic), 5,9,12–18∶3 (pinolenic), or 5,9,12,15–18∶4 (coniferonic)]. These structures support the simultaneous existence of Δ6- and Δ5-desaturase activities in A. robusta seeds. The Δ6-ethylenic bond is apparently introduced into C₁₈ polyunsaturated acids, whereas the Δ5-ethylenic bond is introduced into C₂₀ polyunsaturated acids. A general metabolic pathway for the biosynthesis of unsaturated fatty acids in gymnosperm seeds is proposed. When compared to Bryophytes, Pteridophytes (known to contain arachidonic and eicosapentaenoic acids), and species from other gymnosperm families (without such acids), A. robusta appears as an “intermediate,” with the C₁₈ Δ6-desaturase/C₁₈→C₂₀ elongase/C₂₀ Δ5-desaturase system in common with the former subphyla, and the unsaturated C₁₈→C₂₀ elongase/C₂₀ Δ5-desaturase system specific to gymnosperms. The following hypothetical evolutionary sequence for the C₁₈ Δ6/Δ5-desaturase class in gymnosperm seeds is suggested: Δ6 (initial)→Δ6/Δ5 (intermediate)→Δ5 (final).     

Gold nanoparticle colorants as traditional ceramic glaze alternatives

Historically, Roman stained glass has been a standard for high‐temperature color stability since biblical times but was not properly characterized as emission from nanoparticle plasmon resonance until the 1990s. The methods under which it was created have been lost, but some efforts have recently been made to recreate these properties using gold nanoparticle inks on glassy surfaces. This body of work employs gold nanoparticle systems ranging from 0.015% to 0.100% (wt/wt), suspended in a clear glaze body. The glazes are fired with traditional ceramic methods—in both gas reduction and electric oxidation kilns—in which nanoparticles are retained and can be imaged via TEM. Various colors intensities are reported in addition to changes in nanoparticle size after application and firing. The nanoparticle glazes are compared to traditional red glazes, highlighting the significantly lower metal loading required (5%‐10% for traditional glazes vs 0.100% for gold (wt/wt)), therein. Finally, proof of concept is provided with a functional gold nanoparticle mug, fired in reduction, that costs roughly 0.98$ USD in gold used.     

Achievement of energy focus for distance-of-flight mass spectrometry with constant momentum acceleration and an ion mirror

Distance-of-flight mass spectrometry (DOF-MS) has not yet been implemented, though it has many potential advantages in a variety of applications. Impeding the implementation of DOF-MS is the development of the required array detectors and working out the equivalents to the focusing methods now used in time-of-flight (TOF) mass analyzers. Ideally, a batch of ions composed of a variety of m/z values, despite initial distributions of space and energy, would be spatially focused at their respective flight distances at the same time. First-order energy focusing, including ion turnaround, is shown to be accomplished by the use of an ion mirror in conjunction with constant momentum acceleration of the initial ion packet. The initial spatial dispersion is maintained throughout the flight path. With zero initial spatial ion spread, energy focusing to achieve resolutions in the tens of thousands is shown to be feasible with ions from the elemental and isotope ratio mass regions through the extremely high m/z range. With moderate spatial spread taken into account, the DOF-MS approach is shown to achieve resolutions competitive with quadrupole and ion trap mass analyzers. Advantages of DOF-MS include all the advantages of TOF-MS plus simpler detector electronics and the improved signal-to-noise ratio and dynamic range afforded by array detection.     

Effect of fatty acid positional distribution and triacylglycerol composition on lipid by-products formation during heat treatment: I. polymer formation

Effects of the fatty acid positional distribution and of the triacylglycerol (TG) composition on polymerization of TG during heat treatment were studied. Diacid TG molecules, acylated only with linoleic acid or linolenic acid along with palmitic acid, and positioned either in the central position (PLP and PLnP, respectively) or in one of the two outer positions (PPL and PPLn, respectively) were synthesized. Monoacid TG, i.e., trilinolein and trilinolenin, were also synthesized and mixed with tripalmitin in a 1:2 ratio. These model TG were also compared to TG models that consisted of a canola oil and its randomized counterpart, whose fatty acid positional distribution and TG composition were determined by means of high-performance liquid chromatography (HPLC). After heating, the polymer content and composition were evaluated by HPLC-size exclusion chromatography. Both pure TG and the canola oil models showed that acylation of polyunsaturated acids in the central position was protective against polymerization, although the effect was mainly observed with linolenic acid. The synthetic-TG study showed that the monoacid TG species exhibited higher sensitivity toward polymerization than the diacid species. The slight differences in the TG species between both canola oils did not allow observation of such a relationship with regard to TG composition.     

Structures,practical sources (gymnosperm seeds), gas‐liquid chromatographic data (equivalent chain lengths), and mass spectrometric characteristics of all‐cis Δ5‐olefinic acids

In view of the increasing interest of lipid researchers in the biological effects of all‐cis Δ5‐unsaturated polymethylene‐interrupted fatty acids (Δ5‐UPIFA) from vegetable origin, this paper is concerned with their occurrence in practical sources (gymnosperm seeds), structures, and identification by gas‐liquid chromatography (GLC) and mass spectrometry (MS). The use of equivalent chain lengths (ECL) determined by calculations based on available standards, in close agreement with data determined with easily available commercial gymnosperm seeds specific for each Δ5‐UPIFA, allows identification of all Δ5‐UPIFA. These tentative identifications are supported by GLC‐MS of the appropriate (4, 4‐dimethyloxazoline and picolinyl ester) derivatives. ECL are particularly useful to identify Δ5‐UPIFA in tissue lipids from animals experimentally fed oils containing these acids, with no interference with polyunsaturated fatty acids of endogenous origin.