An expert system for preliminary numerical design modelling

This paper is based upon the premise that computers can do more than just ‘number crunching’ to assist a designer in his task. Key features of the design process where traditional computer-aided design (CAD) approaches have had limited success are presented. The approach of expert systems, which shows promise of assisting in these features, is outlined and a system based on this approach, DESIGNER, described. This system can be applied to any numerical design problem and is illustrated through an example from preliminary ship design.     

Effects of substitutions in the binding surface of an antibody on antigen affinity

The interactions between the Fab and single-chain Fv (scFv) fragments of an antibody (NC10) and its antigen, influenza virus neuraminidase, were analysed in the crystal structures of the Fab-neuraminidase and scFv-neuraminidase complexes. To investigate the contribution to binding made by cavities, salt links and hydrogen bonds in the antibody- antigen interface, 14 single amino acid replacements were made at six contact residues in the scFv fragment by site-directed mutagenesis. The binding affinity of each mutant scFv antibody for neuraminidase was determined with a BIAcore optical biosensor. Four of the mutations resulted in large changes in the free energy of binding to neuraminidase (deltadeltaG > 1 kcal/mol) and together may account for approximately 70% of the free energy of binding. Hence these data support the theory that a small number of residues form the 'functional epitope' and are most important for binding of NC10 to neuraminidase. The salt link between antibody residue (Asp)H56 and (Lys)N432 from neuraminidase was demonstrated to be important for affinity, since substitution of (Asp)H56 with Asn caused a large reduction in the free energy of binding (deltadeltaG = +2.8 kcal/mol). Hydrogen bonds provided by (Tyr)L32 and (Asp)H56 were also important for binding: mutation of (Tyr)L32 to Phe resulted in a significant reduction in binding affinity (deltadeltaG = +1.7 kcal/mol). Disruption of hydrophobic interactions (van der Waals contacts) led to significant reductions in affinity also ((Tyr)H99 to Ala, deltadeltaG = +1.5 kcal/mol; (Leu)L94 to Ala, deltadeltaG > +3.0 kcal/mol). An attempt to increase binding affinity by filling a cavity in the interface with a larger antibody side chain was unsuccessful, as the free energy gained by new antibody-antigen interactions did not compensate for the removal of cavity-bound water molecules.      

Microglial FABP4-UCP2 Axis Modulates Neuroinflammation and Cognitive Decline in Obese Mice

The microglial fatty-acid-binding protein 4-uncoupling protein 2 (FABP4-UCP2) axis is a key regulator of neuroinflammation in high-fat-diet (HFD)-fed animals, indicating a role for FABP4 in brain immune response. We hypothesized that the FABP4-UCP2 axis is involved in regulating diet-induced cognitive decline. We tested cognitive function in mice lacking microglial FABP4 (AKO mice). Fifteen-week-old male AKO and wild-type (WT) mice were maintained on 60% HFD or normal chow (NC) for 12 weeks. Body composition was measured using EchoMRI. Locomotor activity, working memory, and spatial memory were assessed using behavioral tests (open field, T-maze, and Barnes maze, respectively). Hippocampal microgliosis was assessed via immunohistochemical staining. An inflammatory cytokine panel was assayed using hippocampal tissue. Real-time RT-PCR was performed to measure microglial UCP2 mRNA expression. Our data support that loss of FABP4 prevents cognitive decline in vivo. HFD-fed WT mice exhibited impaired long- and short-term memory, in contrast with HFD-fed AKO mice. HFD-fed WT mice had an increase in hippocampal inflammatory cytokine expression (IFNγ, IL-1β, IL-5, IL-6, KC/GRO(CXCL1), IL-10, and TNFα) and microgliosis, and decreased microglial UCP2 expression. HFD-fed AKO mice had decreased hippocampal inflammatory cytokine expression and microgliosis and increased microglial UCP2 expression compared to HFD-fed WT mice. Collectively, our work supports the idea that the FABP4-UCP2 axis represents a potential therapeutic target in preventing diet-induced cognitive decline.     

The yeast PRS3 gene is required for cell integrity, cell cycle arrest upon nutrient deprivation, ion homeostasis and the proper organization of the actin cytoskeleton.

PRS3 is one of a family of five genes encoding phosphoribosylpyrophosphate synthetase, an enzyme which catalyses the first step in a variety of biosynthetic pathways, including purine and pyrimidine biosynthesis. We report here that prs3Delta mutants have a number of phenotypes that suggest an unexpected role for PRS3 in linking nutrient availability to cell cycle progression, cell integrity and the actin cytoskeleton. Upon nutrient limitation, prs3Delta mutants fail to arrest in G(1)-cells remain budded and a significant fraction have a G(2) DNA content. Furthermore, in such conditions, prs3Delta mutants have a disorganized actin cytoskeleton: actin accumulates in one or two intensely staining clumps per cell. Prs3Delta mutants also show defects in ion homeostasis and cell integrity. They fail to grow on medium containing 1.0 M NaCl, 5 mM caffeine or when incubated at 37 degrees C. The caffeine and temperature sensitivity are rescued by supplementing the growth medium with 1.0 M sorbitol. These phenotypes resemble those of whi2Delta mutations and indeed, a prs3 allele was recovered in a colony-sectoring screen for mutations that are co-lethal with whi2Delta. However, further investigation showed that the prs3Delta whi2Delta double mutant was viable, with no obvious growth defect compared to either single mutant. In the same colony-sectoring assay, an mpk1 allele was also recovered. Multicopy PRS3 rescued the caffeine sensitivity of this mpk1 allele.     

Development and validation of a probabilistic second-order exposure assessment model for Escherichia coli O157:H7 contamination of beef trimmings from Irish meat plants

A second-order quantitative Monte Carlo simulation model was developed for Escherichia coli O157:H7 contamination of beef trimmings in Irish abattoirs. The assessment considers initial contamination levels, cross-contamination and decontamination events during the cattle slaughter process. The mean simulated prevalence of E. coli O157:H7 on trimmings was 2.36% and the mean simulated counts of E. coli O157:H7 on contaminated trimmings was -2.69log(10)CFU/g. A parallel validation survey provided some confidence in the model predictions. An uncertainty analysis indicated that microbial test sensitivity is a significant factor contributing to model uncertainty and requires further investigation while also indicating that risk reduction measures should be directed towards reducing the hide to carcass transfer (correlation coefficient 0.25) during dehiding and reducing the initial prevalence and counts on bovine hides (correlation coefficients 0.19 and 0.16, respectively). A characterisation of uncertainty and variability indicating that further research is required to reduce parameter uncertainty and to achieve better understanding of microbial transfer in meat plants. The model developed in this study highlights the need for further development of quantitative risk assessments in the food industry.     

Bcl-xL functions downstream of caspase-8 to inhibit Fas- and tumor necrosis factor receptor 1-induced apoptosis of MCF7 breast carcinoma cells

Stimulation of the Fas or tumor necrosis factor receptor 1 (TNFR1) cell surface receptors leads to the activation of the death effector protease, caspase-8, and subsequent apoptosis. In some cells, Bcl-xL overexpression can inhibit anti-Fas- and tumor necrosis factor (TNF)-alpha-induced apoptosis. To address the effect of Bcl-xL on caspase-8 processing, Fas- and TNFR1-mediated apoptosis were studied in the MCF7 breast carcinoma cell line stably transfected with human Fas cDNA (MCF7/F) or double transfected with Fas and human Bcl-xL cDNAs (MCF7/FB). Bcl-xL strongly inhibited apoptosis induced by either anti-Fas or TNF-alpha. In addition, Bcl-xL prevented the change in cytochrome c immunolocalization induced by anti-Fas or TNF-alpha treatment. Using antibodies that recognize the p20 and p10 subunits of active caspase-8, proteolytic processing of caspase-8 was detected in MCF7/F cells following anti-Fas or TNF-alpha, but not during UV-induced apoptosis. In MCF7/FB cells, caspase-8 was processed normally while processing of the downstream caspase-7 was markedly attenuated. Moreover, apoptosis induced by direct microinjection of recombinant, active caspase-8 was completely inhibited by Bcl-xL. These data demonstrate that Bcl-xL can exert an anti-apoptotic function in cells in which caspase-8 is activated. Thus, at least in some cells, caspase-8 signaling in response to Fas or TNFR1 stimulation is regulated by a Bcl-xL-inhibitable step.     

Measuring individual research productivity: A review and development of the integrated research productivity index.

The purpose of the present study was to investigate methods of measuring individual research productivity for counseling psychologists. Using the 60 members of the Journal of Counseling Psychology editorial board, the authors computed a comparison of 6 popular indices of productivity, revealing considerable levels of positive skewness, kurtosis, and overlap with each other. Combining the strengths of the 6 indices, the authors developed a new productivity index entitled the Integrated Research Productivity Index (IRPI). The IRPI measures individual productivity by statistically combining an individual's author-weighted publications, average times cited by other publications, and years since first publication into a comprehensive score. Productivity values and IRPI scores for 3 groups of counseling psychologists (Tyler Award recipients, Kuder Award recipients, and Division 17 Presidents) were computed to provide evidence of discriminant validity among the indices. In contrast to the other measures examined, the IRPI accounts for productivity per year and years in the field and assesses mean citation count per article as opposed to total citation count, thus yielding similar scores for Tyler (lifetime) and Kuder (early career) research award recipients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical trial of retrograde warm blood reperfusion versus standard cold topical irrigation of transplanted hearts

BACKGROUND: A prospective, randomized clinical study involving 34 patients undergoing heart transplantation compared myocardial preservation of donor hearts maintained with continuous reperfusion with retrograde warm blood cardioplegia during surgical implantation versus the standard cold topical irrigation. METHODS: Hearts in both groups were arrested with a standard crystalloid solution and maintained in a cold saline solution during transportation. In the retrograde group, cardioplegia was administered through a catheter in the coronary sinus during surgical implantation. An average of 471 +/- 30 mL of hyperkalemic crystalloid solution diluted 1:4 in warm blood from the oxygenator was infused. In the standard group, the heart was kept cold by topical irrigation of cold saline solution and was reperfused only when the ascending aorta was unclamped. RESULTS: Preoperative characteristics of donors and recipients were similar in the two cohorts. Ischemic time average 139 +/- 12 minutes in the retrograde group compared with 130 +/- 11 minutes in the standard group (p = 0.57). Cardiopulmonary bypass time averaged 89 +/- 4 minutes in the retrograde group and 110 +/- 12 minutes in the standard group (p = 0.12). Defibrillation at reperfusion was performed in 4 patients (4/17, 24%) in the retrograde group and 12 patients (12/18, 67%) in the standard group (p = 0.01). There were no deaths in the retrograde group (0/17), whereas in the standard group, 3 patients (3/17) died of early graft failure (p = 0.11). Four early graft failures occurred in the standard group (p = 0.06). Two patients (2/17, 12%) were weaned from bypass with ventricular assist devices in the standard group. The number of subendocardial necrotic cells in the first two weekly endomyocardial biopsy specimens averaged 2.7 +/- 0.8 cells/mm2 in the retrograde group and 5.9 +/- 2.4 cells/mm2 in the standard group (p = 0.12). CONCLUSIONS: Retrograde warm blood reperfusion appears to improve the initial recovery of transplanted hearts. The technique is easy to use and may be a useful approach to graft protection during surgical implantation.     

Ryanodine action at calcium release channels. 1. importance of hydroxyl substituents

Ryanodine (1) and dehydroryanodine (2) have a polar face formed by cis-hydroxyls at C-2, C-4, C-6, and C-12. The importance of the hydroxyls to the action of 1 and 2 at the ryanodine receptor (ryr) of calcium release channels is examined at [3H]-1 binding sites in brain and skeletal muscle and in heart membranes relative to cardiac contractility, a pharmacologic response which appears to be mediated by the ryr. Five types of changes are considered: blocking the 4- and 6-hydroxyls as cyclic borates and boronates; blocking the 10- and 12-hydroxyls as cyclic phosphates, phosphonates, and phosphoramidates; methylation at nitrogen or hydroxyls at C-4 and C-10; dehydration of the C-2 hydroxyl; additional data for a 4,12-oxygen-bridged series. The first change has little effect on potency possibly due to the lability of the boron protective groups whereas the cyclic phosphorus compounds have reduced activity. Methylation reduces potency the least at nitrogen and the C-4 hydroxyl. Dehydration of 1 to 2-deoxy-2(13)-dehydro-1 allows the restoration of oxygen at C-2 by conversion to epoxides or a diol. One of the epoxides and 2-deoxy-2(13)-dehydro-2 retain 8-31% of ryanodine's potency in the ryr assays and 81% in the cardiac contractility system. In the 4,12-oxygen-bridged series, high potency at the receptor and cardiac muscle is retained in the 4-hydroxy ketal.