Changes in the size and docosahexaenoic acid content of adipocytes during chick embryo development

The development of adipose tissue in the chick embryo was investigated using two groups of fertile eggs which differed by 1.7-fold in their initial yolk lipid levels. The triacylglycerol content of the subcutaneous adipose depot in both groups increased dramatically from day 12 of the 21-day embryonic period, attaining a maximal value just prior to hatching. During this period, the amount of triacylglycerol deposited in the adipose tissue was very highly correlated with the amount of lipid transferred from the yolk. The triacylglycerol content of the depot was also dependent on the initial yolk lipid content. During the hatching period, the amount of adipose triacylglycerol remained approximately constant in the group with the higher initial yolk lipid content but, in the case of the group with the lower initial yolk lipid levels, decreased by approximately 25%. The size distribution of adipocytes isolated from the tissue was determined by computerized image analysis microscopy. The mean adipocyte diameter increased from approximately 6 to 35 μm between days 12 and 19, irrespective of the initial yolk content, although development within the eggs with the lower initial yolk content resulted in a decrease in cell size over the hatching period. Both the triacylglycerol and phospholipid fractions of the isolated adipocytes contained substantial proportions (approximately 6%, w/w) of docosahexaenoic acid (DHA) at days 12 and 14, and lower levels of this fatty acid at the later stages. The amount (mg/depot) of DHA in adipose triacylglycerol decreased dramatically over the hatching period. The amount (mg/brain) of DHA in brain phospholipid increased by more than 5-fold between day 12 of development and hatching. A possible explanation for the data may be that DHA is preferentially mobilized from adipose tissue in order to deliver the fatty acid to the developing neural tissues in a form suitable for uptake.     

Developement of neutral polymeric bonding agents for propellants with polar composites filled with organic nitramine crystals

Versatile neutral polymeric bonding agents (NBPA's) have been developed for energetic propellants in which polar HMX particles are dispersed in a polar binder matrix containing highly polar plasticizers (TMETN, NG, etc.). Using a semi-empirical approach through adjustment of solubility parameters and molecular weight, neutral acrylonitrile interpolymers were synthesized which mix uniformly with the submix and still have a high affinity for the HMX particles when they are added. Addition of about 0.2 % w/w of NPBA to HMX-filled PEG binders increases the strength by a factor of as high as five compared to samples with no NPBA, and also eliminates the sudden decrease in modulus (knee) which occurs at relatively low elongation. The degree of filler reinforcement achieved by our NPBA's in energetic propellants is far superior to that achieved by adding nitrocellulose or any other previously proposed bonding agents, and similar to the effect of precoating the HMX particles with polyurea shells.     

The lipid composition of the spleen and intestinal and popliteal lymph nodes in the sheep

Lipids were isolated from the spleen, intestinal lymph nodes and popliteal lymph nodes, tissues of potential importance in the metabolism of lymph or lymphocytes, of the sheep. The most abundant lipid classes were the triacylglycerols, free cholesterol and phospholipids, especially phosphatidylcholine, phosphatidylethanolamine and sphingomyelin. In each lipid class, the amounts of the essential fatty acids were lower than in the corresponding lipids of lymph or plasma. The triacylglycerols of each tissue resembled those of adipose tissue in structure, rather than those of lymph or plasma. Also, the structures of the phosphatidylcholines were distinctive. The results are discussed in terms of the metabolism of lipids in lymph. It does not appear probable that lymphoid tissue can supply appreciable amounts of lipid to lymph.     

Transient measurements of adsorption and diffusion in H-ZSM-5 membranes

A transient permeation method presented here not only determines the adsorption and diffusion properties of the pores that are the transport pathways through zeolite membranes, but nondestructively estimates the effective thickness of the membrane. Transient responses of the permeate concentration to step changes in the feed were measured on two H-ZSM-5 tubular membranes and modeled assuming Maxwell-Stefan diffusion and Langmuir adsorption. The adsorption isotherms determined from these transient measurements at 298 K of N₂ and CO₂ were nearly identical to those measured by calorimetry on H-ZSM-5 powders. The CH₄ isotherm at 298 K was similar to isotherms measured by calorimetry and gravimetric techniques on Na-ZSM-5 and silicalite powders. The similarity of the isotherms indicates that transport of these light gases occurs mainly through zeolite pores. The Maxwell-Stefan diffusion coefficients D_MS depended on concentration and were higher for higher feed partial pressures. Average D_MS values for the two membranes were 7.5, 5 and 1.5×10⁻¹⁰ m²/s for N₂, CH₄, and CO₂, respectively; these are in the same range and order as diffusion coefficients measured in zeolite crystals.     

Chemical Ecology of the host searching behavior in an Egg Parasitoid: are Common Chemical Cues exploited to locate hosts in Taxonomically Distant Plant Species?

Parasitoids are known to exploit volatile cues emitted by plants after herbivore attack to locate their hosts. Feeding and oviposition of a polyphagous herbivore can induce the emission of odor blends that differ among distant plant species, and parasitoids have evolved an incredible ability to discriminate them and locate their hosts relying on olfactive cues. We evaluated the host searching behavior of the egg parasitoid Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) in response to odors emitted by two taxonomically distant host plants, citrus and Johnson grass, after infestation by the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae), vector of Citrus Variegated Chlorosis. Olfactory response of female parasitoids toward plants with no herbivore damage and plants with feeding damage, oviposition damage, and parasitized eggs was tested in a Y-tube olfactometer. In addition, volatiles released by the two host plant species constitutively and under herbivore attack were characterized. Females of C. annulicornis were able to detect and significantly preferred plants with host eggs, irrespectively of plant species. However, wasps were unable to discriminate between plants with healthy eggs and those with eggs previously parasitized by conspecifics. Analysis of plant volatiles induced after sharpshooter attack showed only two common volatiles between the two plant species, indole and β-caryophyllene. Our results suggest that this parasitoid wasp uses common chemical cues released by many different plants after herbivory at long range and, once on the plant, other more specific chemical cues could trigger the final decision to oviposit.

     

Reversible H2 storage using a SAPO-34 zeolite layer

A SAPO-34 zeolite membrane was made essentially impermeable to high-pressure hydrogen at room temperature by adsorbing methanol in the SAPO-34 layer. Hydrogen permeance decreased three orders of magnitude when the methanol feed activity was 0.1, and it decreased more than six orders of magnitude when the methanol feed activity was higher than 0.85 at 293 K. The hydrogen permeance at 293 K was below 10⁻¹⁴ mol/m² s Pa for at least five days for a H₂ feed pressure of 6.6 MPa. At higher temperatures, methanol desorbed and the H₂ flux increased. The hydrogen permeance could be controlled by the activity of the methanol on the feed side. These results demonstrate that the SAPO-34 membrane had low fluxes through defects, and H₂ flow through these defects was blocked by capillary condensation of methanol at high methanol activities.     

Origins of Systems Biology in William Harvey’s Masterpiece on the Movement of the Heart and the Blood in Animals

In this article we continue our exploration of the historical roots of systems biology by considering the work of William Harvey. Central arguments in his work on the movement of the heart and the circulation of the blood can be shown to presage the concepts and methods of integrative systems biology. These include: (a) the analysis of the level of biological organization at which a function (e.g. cardiac rhythm) can be said to occur; (b) the use of quantitative mathematical modelling to generate testable hypotheses and deduce a fundamental physiological principle (the circulation of the blood) and (c) the iterative submission of his predictions to an experimental test. This article is the result of a tri-lingual study: as Harvey’s masterpiece was published in Latin in 1628, we have checked the original edition and compared it with and between the English and French translations, some of which are given as notes to inform the reader of differences in interpretation.     

Supply, need, and distribution of anesthesiologists and nurse anesthetists in the U.S., 1972 and 1980

This paper examines the relationship between problems in anesthesia care delivery and the availability and utilization of trained anesthesia manpower. The 1972 and 1980 projected supply and mix of anesthesiologists and nurse anesthestists is described and compared to the current and projected need for their services. The need estimates developed for anesthesia manpower are based upon published data on operations, productivity and theoretical team configurations. Utilization data are used since they are quantifiable and the need for anesthesia services is, indeed, supply-induced. Two estimates of need are developed based upon differing degrees to which anesthesia teams can be effectively employed, this being contingent upon the size of the hospital operative workload. While the need estimates developed for anesthesiologists for 1972 and 1980 were fairly close in aggregate number to the actual and projected supply; the need estimates for nurse anesthetists fell far short of their 1972 and 1980 projected supply. The 1972 need estimates are then compared on a statewide basis to the actual supply and mix of anesthesia personnel to reveal a severe maldistribution which is quantified in terms of shortage and execesses of anesthesiologists and nurse anesthetists for each state.