Effects of experimental endogenous hyperlipemia on circulating leukocytes and erythrocytes

Effects of hyperlipemia on circulating leukocytes and erythrocytes were studied in dogs which were given repeated, intravenous injections of a nonionic detergent, Triton WR-1339. Erythrocyte lipid concentrations increased from 3.6±0.9 mg/10¹⁰ cells in control animals to 9.3±1.5 mg in the hyperlipemic group. This increase was accompanied by a shift in the distribution of total fatty acids toward a higher percentage of saturated and monounsaturated acids. In contrast to the changes observed in erythrocytes, the leukocyte lipid content remained unaltered in dogs with serum cholesterol levels ranging from 500 to more than 2,000 mg/100 ml. Leukocyte counts rose whereas hematocrit values, hemoglobin concentrations, and erythrocyte counts decreased. Oxygen utilization studies showed no significant metabolic differences between leukocytes which were isolated from hyperlipemic or control animals. Circulating leukocytes in dogs with an endogenously induced hyperlipemia were shown therefore to maintain normal lipid concentrations and did not participate in lipophage formation, as reported for certain diet-induced lipemias.     

Lipid metabolism of acetate-1-14C by leukocytes from dogs fed an arteriosclerosis-inducing diet

Dogs were maintainedoon a control ration or on a semisynthetic diet, containing 5% cholesterol and 16% hydrogenated coconut oil, known to induce hyperlipemia and arteriosclerosis. Circulating leukocytes isolated from dogs fed the coconut oil containing diet were shown to incorporate 50% more radioactivity into lipids than control leukocytes when incubated with acetate-1-¹⁴C. This increase, expressed as dpm/mg of leukocyte DNA, was not specific for any particular lipid since the distribution of radioactivity between neutral lipids and phospholipids, as well as among their subfractions, was the same regardless of the diet fed. The labeling patterns observed suggest that leukocyte fatty acid synthesis from acetate occurs predominantly, and perhaps exclusively, by the chain elongation pathway.     

Approach for Integrating Professional Practice Issues into Undergraduate Environmental Engineering Design Projects

According to C. L. Dym and P. Little, the complete design process includes identifying a need or problem, recognizing constraints, identifying and developing courses of action, testing potential courses of action, selecting optimum courses of action, preparing the documents required for the design, managing the overall process, communicating the design, construction, and testing. We have addressed these design considerations by linking design projects in our introductory physicochemical treatment processes course (EV401, taken by second-semester juniors) and our senior capstone design course (EV490, taken by second-semester seniors). The process developed and implemented addresses the integration of professional practice into design inexperience. We require our cadet students to communicate with their customers, an illustrator, and tradesmen, three forms of communication that are necessarily quite different from traditional student-professor exchanges. Also, students must design under constraints, this time not because of the closed nature of the project but rather because of “real world” resource constraints: time to complete the project, a limited budget to purchase materials and labor, availability of materials, ease of construction, and balancing competing projects (in other courses). The first attempt at implementing this engineering design learning model occurred during the spring of 2001 in EV401. Herein we assess the design and construction of one of two projects, oriented toward modification of a surface-water treatment plant model. Results suggest that iterative growth can occur and a more complete appreciation of the design process can result.     

Design Principles for Cationic,Astrocyte-Targeted Probes

The brain's astrocytes play key roles in normal and pathological brain processes. Targeting small molecules to astrocytes in the presence of the many other cell types in the brain will provide useful tools for their visualization and manipulation. Herein, we explore the functional consequences of synthetic modifications to a recently described astrocyte marker composed of a bright rhodamine-based fluorophore and an astrocyte-targeting moiety. We altered the nature of the targeting moiety to probe the dependence of astrocyte targeting on hydrophobicity, charge, and pK_a when exposed to astrocytes and neurons isolated from the mouse cortex. We found that an overall molecular charge of +2 and a targeting moiety with a heterocyclic aromatic amine are important requirements for specific and robust astrocyte labeling. These results provide a basis for engineering astrocyte-targeted molecular tools with unique properties, including metabolite sensing or optogenetic control.     

Low-cost testing of high-density logic components

The evolution of a testing method and architecture of a logic-device tester to be used for the next generation of IBM's high-density CMOS ASIC (application-specific integrated circuit) logic components is described. The tester's design is based on the architecture of an existing IBM memory tester rather than on a conventional logic-tester design. The testing strategy calls for boundary-scan in each component design, built-in self-test logic within embedded memory arrays, and the use of weighted random-pattern logic testing. The development of the tester hardware is discussed, and capital costs of the new tester are compared with those of other approaches     

Regulation and function of steroid production by mid gestation ovine fetal adrenal cortex in vivo

By mid-gestation (75-85 days, term=150 days), the ovine fetal adrenal gland is zoned into cortex and medulla. The cortex has an outer layer of cells which have the morphological characteristics of zona glomerulosa cells, containing mitochondria with lamellar cristae. It has been reported that cultured adrenal cells from mid-gestation bovine and ovine fetuses can be stimulated to increase aldosterone production, ten fold, by angiotensin II, and that this can be maintained for at least 3 days. However, the situation in vivo is unknown. In the current report we show that in chronically cannulated ovine fetuses at mid-gestation, angiotensin II (1 microg/h) does not increase aldosterone either in the short term (3 hours) or long term (3 days). However, ACTH (450 ng/h) can increase plasma aldosterone in the short but not long term. ACTH at this dose produces progressive and large increases in cortisol production. Angiotensin II is pressor and produces a modest diuresis without stimulating cortisol.     

Expression of aquaporin-1 (AQP1) in the adult and developing sheep kidney

The distributions of aquaporin-1 mRNA and protein were studied by hybridization histochemistry with a homologous riboprobe and immunohistochemistry, in the adult sheep kidney. Heaviest labelling occurred in the thin descending limb (DTL) of the loop of Henle in the inner stripe of the outer medulla, with apparent decreasing expression in the inner medulla, outer stripe of the outer medulla and cortex, but no quantitation was performed. Only proximal tubules (PT) (convoluted and straight) and DTL labelled. The glomerulus showed no labelling, consistent with the pattern in the rat but different to that in the human. During ontogeny, no labelling occurred in the mesonephros at 27 or 41 days of gestation (term = 145-150 days) but other structures did label at 27 days (heart, lung bud, blood vessels surrounding developing spinal cord). Labelling first occurred faintly in the metanephros at 41 days of gestation and increased throughout gestation consistent with morphological development of nephrons.     

CONSIDERING ENVIRONMENTAL CONDITIONS IN THE DESIGN OF BONDED STRUCTURES: A FRACTURE MECHANICS APPROACH

The continued airworthiness of ageing aircraft and long-term durability of new airframes depends, in part, on the integrity of adhesive bonds used for repairs and joining structural components. Additionally, the advent of composite materials and advanced repair techniques incorporating composites has increased the number of adhesively bonded joints specified for use in aerospace structures. Traditionally, adhesive bonds have been analysed and designed using a dependable and rigorous stress-based approach. However, the need to address the effect of bondline flaws and to understand the fatigue characteristics of bonded joints has led to the adoption of a discipline already common in the design of metallic components—fracture mechanics. To understand the durability of bonded structures, however, it is further necessary to examine the effect of environmental exposure on the performance of the adhesive bondline. Familiarity with the stress-based and fracture mechanics analytical approaches, as well as an understanding of environmentally induced trends in bond performance is paramount to quality design. This paper will briefly discuss the attributes of the two main forms of bonded joint analysis, and will broadly outline a design approach that uses fracture mechanics and accounts for environmental effects. Experiments discussed in this paper were performed specifically to use fracture mechanics in assessing the environmental effects on a toughened epoxy adhesive. Results indicate that the Mode I fracture toughness and fatigue crack growth threshold of this adhesive are significantly reduced upon exposure to a high temperature, high humidity aircraft service environment. These results will be used to illustrate the philosophical arguments supporting the design approach.     

Feasibility of the silver-UV process for drinking water disinfection

A synergistic effect between cationic silver and UV radiation (silver-UV disinfection) has been observed that can appreciably enhance inactivation of viruses. The purpose of this work was to assess the feasibility of this technique for drinking water disinfection and evaluate the effects of selected impurities, found in fresh water, and common parameters on inactivation of the coliphage MS-2 with the silver-UV process. Turbidity (kaolin), calcium hardness, carbonate alkalinity, and pH did not significantly degrade inactivation. Inactivation was reduced in the presence of chloride, at concentrations greater than 30 mg/L, and in water samples with UV-254 absorbance values greater than ca. 0.1 cm⁻¹. Inactivation of MS-2 with silver-UV disinfection was also reduced at high phosphate concentrations (above ca. 5 mM). Silver-UV inactivation of MS-2 increased with increases in temperature between 10 and 20 °C. Silver-UV inactivation of MS-2 was increased by greater than 1-log over UV alone, in two untreated fresh water sources, which indicates that silver-UV may be a viable treatment technology. An assessment of operation and management costs suggests that an increase in inactivation of MS-2 with silver-UV disinfection could be economically beneficial.