Optimization of Pathogen Capture in Flowing Fluids with Magnetic Nanoparticles

Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h⁻¹. Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (c_e), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications.     

Comment and discussion on digital processing of PD pulses

Some of the more salient aspects of the digital processing technology of PD signals are examined. Most of the efforts in this field are concentrated on the application of digital analyzers for pulse height analysis, pattern recognition and identification of the physical phenomena. It is demonstrated that errors in the signal processing unit can lead to dominant mistakes in the interpretation of the test results     

Identification of a gene that causes primary open angle glaucoma

Glaucoma is a major cause of blindness and is characterized by progressive degeneration of the optic nerve and is usually associated with elevated intraocular pressure. Analyses of sequence tagged site (STS) content and haplotype sharing between families affected with chromosome 1q-linked open angle glaucoma (GLC1A) were used to prioritize candidate genes for mutation screening. A gene encoding a trabecular meshwork protein (TIGR) mapped to the narrowest disease interval by STS content and radiation hybrid mapping. Thirteen glaucoma patients were found to have one of three mutations in this gene (3.9 percent of the population studied). One of these mutations was also found in a control individual (0.2 percent). Identification of these mutations will aid in early diagnosis, which is essential for optimal application of existing therapies.     

Extensive genomic conservation of cattle microsatellite heterozygosity in sheep

We report the evaluation of 1036 bovine microsatellite primer pairs for their suitability as linkage markers in sheep. Approximately 58% (605/1036) of bovine primer pairs amplified a locus in sheep. Sixty-seven per cent (409/605) of amplified loci were detected as polymorphic. Marker heterozygosity, allele number and range of allele sizes were significantly lower in sheep than cattle sampled in this study. However, median fragment size was similar. These data suggest that high-resolution comparative linkage maps between closely related species can be constructed relatively efficiently.     

The oxidation resistance and constitution of Y9Co7 and nearly-relatedcompounds

The ratio of the thermal oxidation parameter to the decomposition point (T _p/T _m) is of the order of 0 85 for Y₉Co₇, indicating a high degree of chemical binding. The persistence of high values of this ratio has been investigated with respect to (a) other compounds in the Y-Co system, (b) replacement of cobalt in Y₉Co₇ by other d-e!ements, and (c) replacement of yttrium by other rare-earth elements. High ratios are found for (a) Y-Co compounds where Y/Co > 0.5, (b) Y-3d compounds with cobalt and niche! only, end (c) RE-Co compounds generally. However, there are differences in level of the ratio amongst the rare-earth compounds, from which it is inferred that the highest values coincide with full electron shells, that is, without participation of 4f electrons. Additional work is described on an effect of preparation arc-melting current 0n theT _p value for Y₉Co₇, and on compounds of the same pattern where both components are changed.     

Greater behavioral effects of stress in immature as compared to mature male mice

The effect of sexual maturity on behavioral effects of stress was examined in male mice. Immature (4-week-old) or mature (8-week-old) animals were subjected to either social stress (exposure to an isolated adult male) or restraint stress for 5 days and examined for body weight, food intake, or plus-maze behavior. Social stress reduced food intake, body weight, and open-arm entries in 4-week-old but not 8-week-old mice. Restraint reduced body weight in 4-week-old but not 8-week-old mice. It is concluded that immature male mice show greater behavioral disturbances after stress than their mature counterparts. The findings are in agreement with much anecdotal evidence that children are more vulnerable to stress than adults.