Effects of intracerebroventricular infusion of leptin in obese Zucker rats

We have previously reported that the dopaminergic projection from A10 ventral tegmental neurons to the central amygdala is, in part, responsible for the facilitatory effect of angiotensin II (AII) and its 3-7 fragment [AII(3-7)] on the retrieval of information in memory motivated affectively and also on recognition memory. In this study, the influence of both angiotensins, given intracerebroventricularly at the dose of 1 nmol each, in rats lesioned with 6-OHDA to the nucleus accumbens septi (NAS) and to the nucleus septi lateralis (NSL) on recognition memory was evaluated. AII and its 3-7 fragment significantly improved object recognition in sham-operated to NAS and to NSL groups of rats. Bilateral 6-OHDA lesions to NAS totally abolished and to NSL significantly attenuated the facilitatory effect of both angiotensins on object recognition. These results suggest that the dopaminergic projection arriving to the septal structures. NAS and NSL takes part in the facilitatory effect of angiotensins on recognition memory.     

Biochemistry and pharmacokinetics of potent non-steroidal cytochrome P450(17alpha) inhibitors

Two potent non-steroidal inhibitors (CB7645 and CB7661) of human cytochrome P450(17alpha) were tested for in vivo activity in WHT mice. There were no signs of toxicity, but there was no effect on the androgen-dependent organs. The pharmacokinetics and biochemistry of the compounds in mice were investigated. Following i.p. administration of 0.5 mmol/kg of CB7645 and CB7661, peak plasma levels of 13.4 and 3.4 microM, respectively, occurred after 2-4 h, both compounds were cleared rapidly (terminal half-lives 2.7 and 3.3 h, respectively) and neither was detectable at 24 h. CB7645 produced some decrease in plasma testosterone at 4 h, but this was not sustained. When tested in vitro against the WHT testicular enzyme, the CB7645 and CB7661 were competitive inhibitors with K(i) values of 10 and 13 nM, respectively. However, the K(m) for the substrate progesterone was lower at 4.3 nM. These data indicate that, for effective and continuous inhibition of the murine cytochrome P450(17alpha) enzyme, higher peak levels of the compounds would be required, and these levels would need to be maintained throughout the treatment period.     

DECOMPOSITION OF CHANGE IN SPATIAL EMPLOYMENT CONCENTRATION: AN INFORMATION-THEORETIC EXTENSION OF SHIFT-SHARE ANALYSIS

ABSTRACT This paper develops a Kullback-based information-theoretic framework for the extended shift-share models of the Esteban-Marquillas/Areelus variety It also outlines an interpretative structure for managing the findings in model applications. In so doing, the method frees shift-share from some of the criticisms that have been leveled against it. and broadens and generalizes its applicability in economics, regional science, and geography.     

Student Cooperative Learning Workshops Go Mainstream: UMR's Excel Program

We offer cooperative learning workshops to all students enrolled in our largest lower division math and science courses where failure rates are high. Participation in the workshops is related to retention and higher academic achievement among engineering students of various abilities. In the tradition of workshops developed for disadvantaged students in mathematics, science, and engineering, our students meet outside of class in structured group meetings. Our contributions to this tradition include application to a broader range of courses, the inclusion of all types of students, and enhanced training of workshop facilitators in small group communication methods and modern leadership techniques. Our approach is readily adaptable to most institutions.     

Vibration of ring-stiffened circular cylinders under external water pressure

The paper describes a theoretical and an experimental investigation into the free vibration of three ring-stiffened circular cylinders subjected to various values of uniform external pressure. The experimental procedure involved a novel device, which was suitable for ferrous metals. The theoretical method involved the finite element method for both the structure and the fluid, where in the case of the latter, the wave equation was solved. The results showed that the resonant frequencies decreased with increasing values of external pressure, especially when the vibration eigenmode had the same shape as the static buckling mode.     

Land and landlessness among rural-to-rural migrants in Nepal's Terai region

"Nepal has been experiencing a permanent rural-to-rural migration of households from the central hill zone to the Terai region. Migrant households, due to the structure of the Terai economy, are impelled to acquire control of land for subsistence agriculture by squatting, purchasing, or receiving a grant. A household's ability to maximize subsistence opportunities is partly a function of the means by which land is acquired and whether land is acquired at all. Factors which determine the chances of acquiring land reflect the role of institutional rigidities such as the distribution of wealth and the caste structure, state-imposed land reform policies, and such household characteristics as family size and risk aversion. A multinomial logit model is used to empirically assess the importance of these elements in the outcomes of migrant households' resource acquisition decisions."     

Calculations of gas phase diffusion and reaction in heterogeneous catalysts the importance of viscous flow

The problem of multicomponent gas phase diffusion fora single overall reaction in porous catalysts is analyzed using the dusty-gas theory. Recent authors have shown that neglecting internal pressure gradients results in modeling inconsistencies and errors in computation in small pore catalysts. However, calculations based upon kinetic theory estimates of the transport coefficients reveal that the viscous flow contribution to the component i molar flux can be neglected with excellent justification. The resulting equations are internally consistent and greatly simplified. For illustrative purposes the multicomponent example of P. Schneider⁷ is reformulated to take into account nonuniform pressure (but negligible viscous flux), and as a consequence the inconsistency noted in the original reference is removed. Two methods for computing the effectiveness factor are discussed.     

Identification of sex pheromone of calendula plume mothPlatyptilia williamsii

The sex pheromone of the calendula plume moth,Platyptilia williamsii was identified as (Z)-11-hexadecenal (Z11–16Aid). Extracts of female sex pheromone glands contained several compounds when analyzed by capillary and packed-column GLC. However, airborne collections of volatiles from glands contained only one of these compounds, having the same retention time asZ11–16Ald. GC-MS and microozonolysis analyses of the natural product were consistent with those of syntheticZ11–16Ald. In a flight tunnel, males oriented upwind and touched sources ofZ11–16Ald and gland extract with equal frequency. Field tests of syntheticZ11–16Ald already have shown it to be a potent sex attractant for males of this species. This study further supports the hypothesis thatP. williamsii and a sympatric species,Platyptilia carduidactyla, are not reproductively isolated by chemical differences in the composition of the sex pheromone, but rather by temporal differences in sexual activities.     

Mechanism of decreased arachidonic acid in the renal cortex of rats with diabetes mellitus

The purpose of this study was to investigate the roles of decreased synthesis and increased consumption in the depression of arachidonic acid levels in renal cortex and glomeruli of rats with streptozotocin-induced diabetes mellitus. In diabetic rats, arachidonic acid was depressed 33.2% in renal cortex, 47.4% in liver and 66.1% in heart compared to values of control rats. Δ6 Desaturase activity was depressed in renal cortex, liver and heart of diabetic rats to 53.3, 55.5 and 63.7%, respectively, of control values. Δ5 Desaturase activity was also depressed 43.7, 55.5 and 47.6% in renal cortex, liver and heart of diabetic rats, respectively. In other rats the activities of five enzymes involved in the synthesis and esterification of arachidonic acid were measured in renal cortex and in isolated glomeruli. Both tissues from diabetic rats showed depressed activities of Δ5 and Δ6 desaturases, increased activities of long-chain acyl-CoA synthetase and 1-acyl-sn-glycero-3-phosphocholine acyltransferase and no change in the activity of elongase as compared to those in control tissues. Malondialdehyde, an end product of lipid peroxidation, was lower in the renal cortex of diabetic rats than in control rats, whereas β-oxidation of linoleic acid and arachidonic acid were similar in diabetic and in control rats. Basal and stimulated prostaglandin E² synthesis were significantly higher in isolated glomeruli from diabetic rats compared to those in control rats. In isolated tubules, prostaglandin E₂ synthesis was similarly low in both groups. From these data we conclude that the reduced level of arachidonic acid esterified in lipids of the kidney cortex is caused principally by depressed synthesis of arachidonic acid secondary to decreased activity of Δ5 and Δ6 desaturases. Increased consumption of arachidonic acid to support prostaglandin synthesis may have contributed to the depression of arachidonic acid in glomeruli but not in tubules.     

Mechanical Properties of Acrylic Pressure Sensitive Adhesives and Their Relationships to Industry Standard Testing

Dynamic mechanical and tensile stress-strain properties were measured for four sets of acrylic pressure sensitive adhesives, and were compared to industry standard “applications” peel and shear properties. Correlations were established showing that more than half of the range of performance shown by commercial PSA's is controlled by the bulk mechanical properties of the adhesive polymer. A few exceptions stand out clearly. Also, room temperature performance properties were found to correlate better with DMA at higher temperatures than with room temperature DMA. The contribution of tensile properties to peel strength and failure mode is discussed. The results can be used to relate PSA performance to well-known concepts in other areas of materials science, e.g. fracture toughness, rubber elasticity, and rheology, and to key variables in the adhesive formulation or selection process.