In vitro yields and in vivo activity of a polyhedrin gene-deleted and wild strain of the nucleopolyhedrosis virus of Autographa californica

A range of biomaterials are used in rendering prosthodontic treatment for the completely edentulous patient. This article reviews the biomaterials considerations in the use of metals and metal alloys, ceramics and carbons, and synthetic materials for implant therapy. It also discusses implant material selection, biomaterial aspects of bioadhesion, and osseointegration and hygiene-related biomaterial factors.     

Evolution on a volcanic conveyor belt: using phylogeographic reconstructions and K-Ar-based ages of the Hawaiian Islands to estimate molecular evolutionary rates

This article reports dissociations between verbal span and the recency portion of the serial position curve in immediate free recall, in 2 neuropsychological case studies and in 3 experiments with normal participants. Patient A. N. presented with an impaired serial verbal span while showing an intact recency effect. The opposite pattern was observed in patient G. C., who despite a poor recency showed normal span in verbal serial recall tasks. Experiments 1 and 2 showed a recency effect with visually and auditory presented lists and written recall was resistant to the effects of articulatory suppression and of irrelevant speech, but was disrupted by the suffix effect. Experiment 3 showed that in contrast with recency, memory span was affected by articulatory suppression and irrelevant speech during presentation but not by a suffix. These findings are not consistent with the idea that span and recency measure aspects of the same memory system. Moreover, in clinical practice, they should not be used as equivalent alternatives.     

Mesenchymal stem cells combined with biphasic calcium phosphate ceramics promote bone regeneration

The reconstruction and repair of large bone defects, resulting from trauma, cancer or metabolic disorders, is a major clinical challenge in orthopaedics. Clinically available biological and synthetic grafts have clear limitations that necessitate the development of new graft materials and/or strategies. Human mesenchymal stem cells (MSCs), obtained from the adult bone marrow, are multipotent cells capable of differentiating into various mesenchymal tissues. Of particular interest is the ability of these cells to differentiate into osteoblasts, or bone-forming cells. At Osiris, we have extensively characterized MSCs and have demonstrated MSCs can induce bone repair when implanted in vivo in combination with a biphasic calcium phosphate, specifically hydroxyapatite/tricalcium phosphate. This article reviews previous and current studies utilizing mesenchymal stem cells and biphasic calcium phosphates in bone repair.     

Glycine metabolism in Candida albicans: characterization of the serine hydroxymethyltransferase (SHM1, SHM2) and threonine aldolase (GLY1) genes

Genes encoding the mitochondrial (SHM1) and cytosolic (SHM2) serine hydroxymethyltransferases, and the L-threonine aldolase gene (GLY1) from Candida albicans were cloned and sequenced. All three genes are involved in glycine metabolism. The C. albicans Shm1 protein is 82% identical to that from Saccharomyces cerevisiae and 56% identical to that from Homo sapiens. The corresponding identities for the Shm2 proteins are 68% and 53%. The Gly1 protein shares significant identity with the S. cerevisiae L-threonine aldolase (55%) and also with threonine aldolases from Aeromonas jandiae (36%) and Escherichia coli (36%). Genetic ablation experiments show that GLY1 is a non-essential gene in C. albicans and that L-threonine aldolase plays a lesser role in glycine metabolism than it does in S. cerevisiae. GenBank Accession Nos of the C. albicans SHM1 and SHM2 are AF009965 and AF009966, respectively. Accession No. for C. albicans GLY1 is AF009967.     

Fluorescence lifetime for on-the-fly multiplex detection of DNA restriction fragments in capillary electrophoresis

This paper describes the first use of frequency-domain fluorescence lifetime for multiplex detection of DNA restriction fragments in capillary electrophoresis (CE). The fragments were labeled with monomeric intercalating dyes that can be excited by either the 488- or 514-nm line of an argon ion laser and have lifetimes in the range of 0.5-2.5 ns. We were able to achieve multiplex lifetime detection in the CE separation of a restriction fragment digest and a DNA size ladder in the same run, for fragments shorter than 700 bp. Different gel buffer systems, including a modified polyacrylamide gel and several tris-borate-EDTA/hydroxyethylcellulose (TBE/HEC) gels, were investigated for separation and detection of the dye-labeled DNA fragments. Best results for both electrophoretic resolution and lifetime detection were obtained using a gel containing 1% high molecular weight (90,000-105,000) HEC and 0.3% low molecular weight (24,000-27,000) HEC in TBE buffer.     

Flow induced surface switching in a bistable nematic device

A surprising feature of liquid crystals is that rapid changes in alignment in these anisotropic liquids can induce significant flow, termed backflow, which in turn influences the alignment. A recent paper has suggested that such backflow may be the mechanism behind the fast switching observed in certain bistable nematic cells on the application of electric fields. In these experiments a weakly chiral nematic with unequal monostable surface anchorings is switched rapidly between a uniform and a -twist configuration, and it is conjectured that the backflow induced initially at the more strongly anchored surface plays a crucial role in the switching process. In this paper continuum theory is employed for nematic liquid crystals to investigate this phenomenon, and confirms that backflow can play an important role in the switching.     

Optimum pulse transmission through an exponential plasma inhomogeneity

The optimum transmission of electromagnetic waves through a thin exponentially inhomogeneous plasma region is treated in this communication. Matched filter theory is used in obtaining integral expressions for optimum transmitted signals, which result in received signals that have the largest possible amplitude when transmitted through the plasma region. The fast Fourier transform algorithm is used in obtaining signal waveforms for a number of examples.     

Time-resolved measurements of excited state densities in a coppervapor laser

Time-resolved measurements of copper and neon buffer gas excited-state densities in a copper vapor laser (CVL) during the excitation pulse and early afterglow are reported for both optimum and nonoptimum power-input conditions. The optimum condition results demonstrate that the termination of the laser pulse in the CVL is due not only to filling of the lower laser level, but also to a reduction in the upper laser-level pumping related to the collapse of power input to the plasma during the excitation pulse. Time-resolved measurements of excited-state densities over a wide range of input-power conditions clearly illustrate that the increase in copper density with power input reduces the peak electron temperature in the plasma during the excitation pulse. This reduction in peak electron temperature is important in limiting the scaling of CVL output power with input-power-copper density     

The Role of Sediments in the Nitrogen Budget of Lower Green Bay,Lake Michigan

The extreme southern portion of Green Bay is a shallow (1 to 5 m depth), eutrophic water body which receives considerable nutrients from the Fox River and metropolitan Green Bay, Wisconsin. Research to evaluate the effect of sediments on nitrogen (N) in the bay entailed periodic sampling of waters and sediments at six sites over 20 months and laboratory investigations of the rates of nitrification, denitrification, mineralization, immobilization, and N₂ fixation. The monitoring data indicated that the N concentrations, approximately 0.6 and 0.8 mg/L of inorganic and organic N, respectively, in the bay waters are considerably higher than the threshold limits that may cause algal bloom and aquatic weed problems. Consideration of the available sediment N pool with respect to recognizable N inputs indicated that only 1.2 percent of the yearly N loading from the Fox River is present in the active sediment layer. Nitrification and subsequent denitrification at the sediment-water interface as a result of intermittent wind stirring could be a major sink for N, but presently it has a minor impact due to the high loading rate of N in this ecosystem. The study indicates that even if approximately 50 percent of the present point source loading of N were eliminated by pollution abatement, the N input from nonpoint sources (combined with existing concentrations of phosphorus in the bay waters) would be sufficient to maintain eutrophic conditions.