Altered cholesterol metabolism in a hypercholesterolemia -resistant rabbit colony

A colony of rabbits has been developed at the University of Texas Medical School at Houston that is resistant to dietary-induced hypercholesterolemia. The liver of resistant rabbits had higher levels of ($\sp{125}$I) $\beta$-VLDL binding and 3-hydroxy-3-methylglutaryl (HMGCoA) reductase activity, but lower acyl coenzyme A:cholesterol acyltransferase (ACAT) activity than normal rabbits. Direct quantitation of intracellular cholesterol content of the liver revealed that the resistant rabbits had $<$10% of the intracellular free cholesterol present in normal rabbits. Fibroblasts isolated from normal and resistant rabbits exhibited differences in ($\sp{125}$I) LDL binding, HMGCoA reductase activity and ACAT activity that were similar to those found in the liver. No structural differences were found in the LDL receptor of normal and resistant fibroblasts that would account for the increased binding capacity of the resistant cells. The regulation of LDL receptor levels by exogenous oxygenated sterols was similar in normal and resistant fibroblasts. The regulation of LDL receptor binding capacity by LDL was attenuated in the resistant compared to normal fibroblasts, suggesting that the resistant fibroblasts have an alternate pathway for processing lipoprotein-derived cholesterol. Sterol-balance studies revealed that the cholesterol-fed resistant rabbits increased lithocholic acid excretion compared to the basal state, and had higher levels of deoxycholic acid excretion than cholesterol-fed normal rabbits. In addition, the specific activity and mRNA levels of cholesterol 7$\alpha$-hydroxylase (C7$\alpha$H) were higher in resistant rabbits than normal rabbits, suggesting that the increased bile acid excretion was due to an increase in bile acid synthesis. Increased clearance of cholesterol relieves the negative feedback inhibition cholesterol exerts on expression of the LDL receptor. The number of cell surface LDL receptors is then increased in resistant rabbits and allows rapid clearance of lipoproteins from the plasma compartment, thereby reducing plasma cholesterol levels. The low intracellular cholesterol level also relieves the negative feedback inhibition cholesterol exerts on HMGCoA reductase. Increased synthesis of cholesterol from acetate provides cells with cholesterol for bile acid synthesis and/or homeostasis. The activity of ACAT is then decreased due to the flux of cholesterol through the bile acid synthetic pathways. ^

Design, synthesis and cellular and molecular pharmacology of 2$\sp\prime$-bromo-4$\sp\prime$-epidaunorubicin (WP401): A novel non-cross-resistant anthracycline antibiotic with the intrinsic ability to circumvent P -glycoprotein-mediated drug resistance

We designed and synthesized a novel daunorubicin (DNR) analogue that effectively circumvents P-glycoprotein (P-gp)-mediated drug resistance. The fully protected carbohydrate intermediate 1,2-dibromoacosamine was prepared from acosamine and effectively coupled to daunomycinone in high yield. Deprotection under alkaline conditions yielded 2$\sp\prime$-bromo-4$\sp\prime$-epidaunorubicin (WP401). The in vitro cytotoxicity and cellular and molecular pharmacology of WP401 were compared with those of DNR in a panel of wild-type cell lines (KB-3-1, P388S, and HL60S) and their multidrug-resistant (MDR) counterparts (KB-V1, P388/DOX, and HL60/DOX). Fluorescent spectrophotometry, flow cytometry, and confocal laser scanning microscopy were used to measure intracellular accumulation, retention, and subcellular distribution of these agents. All MDR cell lines exhibited reduced DNR uptake that was restored, upon incubation with either verapamil (VER) or cyclosporin A (CSA), to the level found in sensitive cell lines. In contrast, the uptake of WP401 was essentially the same in the absence or presence of VER or CSA in all tested cell lines. The in vitro cytotoxicity of WP401 was similar to that of DNR in the sensitive cell lines but significantly higher in resistant cell lines (resistance index (RI) of 2-6 for WP401 vs 75-85 for DNR). To ascertain whether drug-mediated cytotoxicity and retention were accompanied by DNA strand breaks, DNA single- and double-strand breaks were assessed by alkaline elution. High levels of such breaks were obtained using 0.1-2 $\mu$g/mL of WP401 in both sensitive and resistant cells. In contrast, DNR caused strand breaks only in sensitive cells and not much in resistant cells. We also compared drug-induced DNA fragmentation similar to that induced by DNR. However, in P-gp-positive cells, WP401 induced 2- to 5-fold more DNA fragmentation than DNR. This increased DNA strand breakage by WP401 was correlated with its increased uptake and cytotoxicity in these cell lines. Overall these results indicate that WP401 is more cytotoxic than DNR in MDR cells and that this phenomenon might be related to the reduced basicity of the amino group and increased lipophilicity of WP401. ^

Characterization of the cholesterol 7$\alpha$-hydroxylase promoter in hypercholesterolemia -resistant rabbits

Our laboratory has developed and partially characterized a strain of New Zealand white rabbits that are resistant to the hypercholesterolemia which typically occurs in normal rabbits when fed a cholesterol-enriched diet. This phenotype is most likely attributed to an increase in bile acid excretion by hypercholesterolemia-resistant (CRT) rabbits as a result of elevated enzyme activity of cholesterol 7$\alpha$-hydroxylase (C7$\alpha$H), the rate-limiting enzyme in bile acid synthesis. Northern analysis revealed that CRT rabbits, in comparison to normal rabbits, have a 7-fold greater steady-state C7$\alpha$H mRNA levels irrespective of dietary regimen. The C7$\alpha$H gene in both phenotypes was determined to be a single copy gene. The hypothesis was that the elevated C7$\alpha$H mRNA levels in CRT rabbits, in comparison to normal animals, was due to an increase in the transcription rate of the C7$\alpha$H gene as a result of a mutation in a cis-acting element and/or a trans-acting factor within the hepatocyte. To isolate the C7$\alpha$H gene from both normal and CRT rabbits, genomic libraries were prepared from both phenotypes into $\lambda$GEM12 vectors using conventional techniques. Three CRT and one normal phage clones that contained the C7$\alpha$H gene were identified by screening the library with a series of probes located within different exons of the C7$\alpha$H cDNA. Sequencing analysis confirmed that approximately 1100 bp of the C7$\alpha$H 5'-flanking region from both normal and CRT phenotypes was identical. The increase in C7$\alpha$H mRNA levels was not attributed to a cis-acting mutation within this region. Liver nuclear extracts were prepared from normal and CRT rabbits maintained either on a basal or 0.25% cholesterol-enriched diet and incubated with several radiolabeled DNA fragments from the C7$\alpha$H gene. A 37 basepair region, located between nucleotides $-$452 to $-$416 was identified that had altered binding patterns between normal and CRT rabbits as a function of diet. Two additional regions, $-$747 to $-$575 and $-$580 to $-$442, produced banding patterns which were identical, irrespective of phenotype or diet. In conclusion, these studies suggested that the increase in C7$\alpha$H mRNA in CRT rabbits was due to differences in binding of a cholesterol-responsive transcription factor to the C7$\alpha$H promoter. ^

Significance of tissue transglutaminase expression in multidrug resistant MCF -7 human breast cancer cells

Tissue transglutaminase (tTGase) is an enzyme that catalyzes the posttranslational modification of proteins via Ca2+-dependent cross-linking reactions. In this study, we extended our earlier observation that tTGase is highly expressed in MCF-7 human breast carcinoma cells selected for the multidrug resistance phenotype (MCF-7/DOX). To directly assess the involvement of tTGase in drug resistance, parental MCF-7 (MCF-7/WT) cells were transfected with cDNAs encoding either a catalytically active (wildtype) or inactive (mutant) tTGase protein. Expression of wildtype tTGase led to spontaneous apoptosis in MCF-7/WT cells, while the mutant tTGase was tolerated by the cells but did not confer resistance to doxorubicin. Analysis of calcium by a spectrofluorometric technique revealed that MCF-7/DOX cells exhibit a defective mechanism in intracellular calcium mobilization, which may play a role in preventing the in situ activation of tTGase and thus allowing the cells to grow despite expressing this enzyme. An elevation in intracellular calcium by treatment with the calcium ionophore A23187 induced rapid and substantial apoptosis in MCF-7/DOX cells as determined by morphological and biochemical criteria. Pretreatment of MCF-7/DOX cells with a tTGase-specific inhibitor (monodansylcadaverine) suppressed A12387-induced apoptosis, suggesting the possible involvement of tTGase-catalyzed protein cross-linking activity. A23187-induced apoptosis in MCF-7/DOX cells was further characterized by PARP cleavage and activation of downstream caspases (-3, -6, and -7). Another interesting aspect of tTGase/A23187-induced apoptosis in MCF-7/DOX cells was that these cells failed to show any prototypic changes associated with the mitochondrial (altered membrane potential, cytochrome c release, caspase-9 activation), receptor-induced (Bid cleavage), or endoplasmic reticulum-stressed (caspase-12 activation) apoptotic pathways. In summary, our data demonstrate that, despite being highly resistant to conventional chemotherapeutic drugs, MCF-7/DOX cells are highly sensitive to apoptosis induced by increased intracellular calcium. We conclude that tTGase does not play a direct role in doxorubicin resistance in MCF-7/DOX cells, but may play a role in enhancing the sensitivity of these cells to undergo apoptosis. ^

Evaluation of Soybean Varieties Resistant to Soybean Cyst Nematode

Use of resistant soybean varieties is a very effective strategy for managing soybean cyst nematode (SCN), and numerous SCN-resistant soybean varieties are available for Iowa soybean growers. Each year, public and private SCN-resistant soybean varieties are evaluated in SCN-infested fields in Iowa by Iowa State University personnel. The research described in this report was performed to assess the agronomic performance of SCNresistant soybean varieties and to determine the effects of the varieties on SCN numbers or population densities.

Thinning Scab-resistant Apples with Liquid Lime Sulfur Sprays during Bloom

Growing scab-resistant apple cultivars on fully dwarfing rootstocks increases the feasibility for producing organically grown apples in the Midwest. However, in an organic orchard, fruit thinning to optimize crop load must be done by hand at a very high labor expense. The alternative is biennial bearing and inconsistent supply to meet consumer demands. Recently, sprays containing organicapproved materials such as liquid lime sulfur, fish, and various vegetable oils, salts, and kaolin have been tried alone or in combination for thinning apples with some degree of success. Lime sulfur alone or in combination with spray oil was recently labeled for use in Washington state orchards. This study was undertaken to evaluate the effectiveness of liquid lime sulfur alone and in combination with spray oil applied at various times during bloom on thinning three scab-resistant apple cultivars under Iowa conditions.

Influence of Crop Load on Tree Growth, Yield, and Fruit Quality of Scab Resistant Apples at Harvest

Apple scab, caused by Venturia inaequalis, is a major disease affecting apple production. Breeding programs have developed over 30 releases of scab-resistant cultivars since 1970 with recent ones having much improved quality. Redfree and GoldRush are from a cooperative breeding program involving Purdue, Rutgers, and Illinois universities while Liberty was introduced from the Cornell University breeding program. For these cultivars to gain better acceptance, more information is needed on their cropping capacities and the effect of crop load on fruit quality attributes. Our study was conducted to determine the relationship between increasing crop load on tree growth, fruit size, and fruit quality variables of the three cultivars under Iowa conditions.

Effects of Headline® on Soybean Aphid Resistant and Susceptible Varieties

With the introduction of soybean aphid-resistant varieties, growers have another option for controlling the pest. This study was designed to see how each variety responded to Headline® fungicide at different application timings.

Stable isotope record of sediment core MD98-2177

We present a reconstruction of El Niño Southern Oscillation (ENSO) variability spanning the Medieval Climate Anomaly (MCA, A.D. 800-1300) and the Little Ice Age (LIA, A.D. 1500-1850). Changes in ENSO are estimated by comparing the spread and symmetry of d18O values of individual specimens of the thermocline-dwelling planktonic foraminifer Pulleniatina obliquiloculata extracted from discrete time horizons of a sediment core collected in the Sulawesi Sea, at the edge of the western tropical Pacific warm pool. The spread of individual d18O values is interpreted to be a measure of the strength of both phases of ENSO while the symmetry of the d18O distributions is used to evaluate the relative strength/frequency of El Niño and La Niña events. In contrast to previous studies, we use robust and resistant statistics to quantify the spread and symmetry of the d18O distributions; an approach motivated by the relatively small sample size and the presence of outliers. Furthermore, we use a pseudo-proxy approach to investigate the effects of the different paleo-environmental factors on the statistics of the d18O distributions, which could bias the paleo-ENSO reconstruction. We find no systematic difference in the magnitude/strength of ENSO during the Northern Hemisphere MCA or LIA. However, our results suggest that ENSO during the MCA was skewed toward stronger/more frequent La Niña than El Niño, an observation consistent with the medieval megadroughts documented from sites in western North America.

Larval and post-larval stages of pacific oyster (Crassostrea gigas) are resistant to elevated CO2

Rising anthropogenic carbon dioxide (CO2) dissolving into coastal waters is decreasing the pH and carbonate ion concentration, thereby lowering the saturation state of calcium carbonate (CaCO3) minerals through a process named ocean acidification (OA). The unprecedented threats posed by such low pH on calcifying larvae of several edible oyster species have not yet been fully explored. Effects of low pH (7.9, 7.6, 7.4) on the early growth phase of Portuguese oyster (Crassostrea angulata) veliger larvae was examined at ambient salinity (34 ppt) and the low-salinity (27 ppt) treatment. Additionally, the combined effect of pH (8.1, 7.6), salinity (24 and 34 ppt) and temperature (24 °C and 30 °C) was examined using factorial experimental design. Surprisingly, the early growth phase from hatching to 5-day-old veliger stage showed high tolerance to pH 7.9 and pH 7.6 at both 34 ppt and 27 ppt. Larval shell area was significantly smaller at pH 7.4 only in low-salinity. In the 3-factor experiment, shell area was affected by salinity and the interaction between salinity and temperature but not by other combinations. Larvae produced the largest shell at the elevated temperature in low-salinity, regardless of pH. Thus the growth of the Portuguese oyster larvae appears to be robust to near-future pH level (> 7.6) when combined with projected elevated temperature and low-salinity in the coastal aquaculture zones of South China Sea.

Estudio experimental del Sistema de Albañilería Integral en la construcción de viviendas sismorresistentes. Experimental study of the Integral Masonry System in the construction of earthquake resistant houses

This paper presents the application of the Integral Masonry System (IMS) to the construction of earthquake resistant houses and its experimental study. To verify the security of this new type of building in seismic areas of the third world two prototypes have been tested, one with adobe and the other with hollow brick. In both cases it’s a two-story 6x6x6 m3 house built to scale 1/2. The tests are carried out at the Laboratory of Antiseismic Structures of the Department of Engineering, Pontifical Catholic University of Peru in Lima, in collaboration with the UPM (Technical University of Madrid). This article shows the design process of the prototypes to test, including the sizing of the reinforcements, the characteristics of the tests and the results obtained. These results show that the IMS with adobe or brick remains stable with no significant cracks faced with a severe earthquake, with an estimated acceleration of 1.8 g. Este artículo presenta una aplicación del Sistema de Albañilería Integral (SAI) a la construcción de viviendas sismorresistentes y su estudio experimental. Para verificar su seguridad para su construcción en zonas sísmicas del tercer mundo se han ensayado dos prototipos, uno con adobe, y otro con ladrillo hueco. Se trata de una vivienda de 6x6x6 m3 y dos plantas que se construyen a escala 1/2. Los ensayos se realizaron en el Laboratorio de Estructuras Antisísmicas del Departamento de Ingeniería de la Pontificia Católica Universidad del Perú (PUCP) de Lima en colaboración con la UPM (Universidad Politécnica de Madrid). Este artículo muestra el proceso de diseño de los prototipos a ensayar, incluido el dimensionado de los refuerzos, las características de los ensayos y los resultados obtenidos. Estos resultados muestran que el SAI con adobe o ladrillo permanece estable sin grietas significativas ante un sismo severo, con una aceleración estimada de 1,8 g.

The influence of sulfuric environments on concretes elaborated with sulfate resistant cements and mineral admixtures. Part 1: Concrete exposed to Sodium Sulfate (Na2SO4) = Estudio de la influencia de los medios con presencia de sulfatos en hormigones con cementos sulforresistentes y adiciones minerales. Parte 1: Hormigones expuestos a sulfato sódico (Na2SO4)

The study of sulfate attack in concrete is considered vital for the preservation of the structural integrity of constructions. Its aggressive behaviour causes degradation of the cement matrix which changes the initial properties of the material. In this article, the sulfate resistance of concrete is studied. To that goal, four different concrete mixes were made with sulphur resistant cement. The concretes were tested for compressive strength, transport capacity of sulfates and microstructural properties. An experimental program was proposed in which the concrete samples were submerged in sodium sulphate (Na2SO4) solution. The obtained results were compared with reference values of concretes cured in calcium hydroxide [Ca(OH)2]. According to the results the concrete with ground granulated blast-furnace slag presented the best behavior when exposed to sodium sulphate (Na2SO4) solution. El estudio del ataque de sulfatos en el hormigón se considera de gran importancia para la conservación de la integridad estructural de las construcciones. Su agresividad se basa en la degradación de la matriz cementicia modificando las características iniciales de diseño. En el presente trabajo se estudia la resistencia del hormigón al ataque de sulfatos provenientes de sulfato sódico (Na2SO4). Para llevar a cabo la investigación se diseñaron cuatro dosificaciones de hormigón empleando cementos sulforresistentes y adiciones minerales. Se llevó a cabo una propuesta experimental donde las muestras de hormigón se sumergieron en disolución de sulfato sódico (Na2SO4) de concentración 1M. Posteriormente se realizaron ensayos de resistencia mecánica, capacidad de transporte de sulfatos y propiedades microestructurales, a distintas edades. Los resultados obtenidos se compararon con valores de referencia de mezclas de hormigón curadas expuestas a hi-dróxido cálcico [Ca(OH)2]. De acuerdo a los resultados obtenidos, el hormigón con escoria de alto horno presentó las mejores características de durabilidad frente a sulfatos provenientes de sulfato sódico

The influence of sulfuric environments on concretes elaborated with sulfate resistant cements and mineral admixtures. Part 2: Concrete exposed to Magnesium Sulfate (MgSO4) = Estudio de la influencia de los medios con presencia de sulfatos en hormigones con cementos sulforresistentes y adiciones minerales. Parte 2.Hormigones expuestos a sulfato magnésico (MgSO4)

The present work studies the resistant of the concrete against magnesium sulfate (MgSO4) and compare the results with values obtained previously of the same concretes exposed to sodium sulfate (Na2SO4). Thus, it is possible analyze the influence of the cation type. To that end, four different concrete mixes were made with sulfur resistant cement and mineral admixtures (silica fume, fly ash and blast furnace slag). The concretes were submerged for different period in magnesium sulfate (MgSO4). After that, different tests were carried out to define mechanical and microstructural properties. The results obtained were compared with reference values of concretes cured in calcium hydroxide [Ca(OH)2]. According to the results, the concrete with blast furnace slag presented the best behavior front MgSO4, meanwhile the concretes with silica fume and fly ash were the most susceptible. The resistance of the concrete with blast furnace slag could be attributed to the characteristics of the hydrated silicates formed during the hydration time, which include aluminum in the chemical chain that hinder its chemical decomposition during the attack of magnesium. The magnesium sulfate solution was most aggressive than sodium sulfate solution. El presente trabajo estudia la resistencia de hormigones al ataque de sulfatos provenientes de sulfato magnésico (MgSO4) y compara estos valores con resultados previos de los mismos hormigones atacados con sulfato sódico (Na2SO4). De esta manera se estudia la interacción del catión que acompaña al ion sulfato durante su afectación a la matriz cementicia. Para lo anterior, se diseñaron cuatro dosificaciones empleando cementos sulforresistentes y adiciones minerales (humo de sílice, ceniza volante y escoria de alto horno). Los hormigones se sumergieron, por distintos periodos de tiempo, en disolución de sulfato magnésico (MgSO4) de concentración 1M, para después realizarles ensayos mecánicos y a nivel microestructural. Los valores obtenidos se compararon con los obtenidos en el hormigón de referencia curado en hidróxido cálcico. El hormigón con escoria de alto horno presentó el mejor comportamiento frente a MgSO4, siendo las mezclas de humo de sílice y ceniza volante las más susceptibles. La resistencia del hormigón con escoria se atribuye a las características de los silicatos hidratados formados durante la hidratación, los cuales incorporan aluminio en las cadenas impidiendo su descomposición ante un ataque por magnesio. El medio con sulfato magnésico mostro una mayor agresividad que el medio con sulfato sódico.

Fracture micromechanisms and residual stresses of a highly resistant duplex stainless steel

The paper presents some preliminary results of an ongoing research intended to qualify a highly resistant duplex stainless steel wire as prestressing steel and, gets on insight on (he wires' fracture micromechanism and residual stresses field. SEM fractographic analysis of the stainless steel wires indicates an anisotropic fracture behavior in tension, in presence of surface flaws, attributed to the residual stresses generated through the fabrication process. The residual stresses magnitude influences the damage tolerance, its knowledge being a key issue in designating/qualifying the wires as prestressing steels.