Investigation of electrophoretic exclusion method for the concentration and differentiation of proteins

This work presents a technique termed as "electrophoretic exclusion" that is capable of differentiation and concentration of proteins in bulk solution. In this method, a hydrodynamic flow is countered by the electrophoretic velocity to prevent a species from entering into a channel. The separation can be controlled by changing the flow rate or applied electric potential in order to exclude a certain species selectively while allowing others to pass through the capillary. The exclusion of various proteins is investigated using a flow-injection regime of the method. Concentration of myoglobin of up to 1200 times the background concentration in 60 s was demonstrated. Additionally, negatively charged myoglobin was separated from a solution containing negatively charged allophycocyanin. Cationic cytochrome c was also differentiated from a solution with allophycocyanin. The ability to differentially transport species in bulk solution enables parallel and serial separation modes not available with other separations schemes.     

Mass-sensitive detection of gas-phase volatile organics using disk microresonators

The detection of volatile organic compounds (VOCs) in the gas phase by mass-sensitive disk microresonators is reported. The disk resonators were fabricated using a CMOS-compatible silicon micromachining process and subsequently placed in an amplifying feedback loop to sustain oscillation. Sensing of benzene, toluene, and xylene was conducted after applying controlled coatings of an analyte-absorbing polymer. An analytical model of the resonator's chemical sensing performance was developed and verified by the experimental data. Limits of detection for the analytes tested were obtained, modeled, and compared to values obtained from other mass-sensitive resonant gas sensors.     

Leptin concentration in women is influenced by regional distribution of adipose tissue

Leptin concentrations in humans are increased with obesity, and women have higher leptin concentrations than men. This sex difference reflects the greater fat mass of women. However, there is evidence that factors other than the size of the adipose tissue mass contribute to serum leptin concentrations. This study was undertaken to determine whether anthropometric factors influenced leptin concentrations in our population. Leptin concentrations were measured in 375 persons from a population study of hypertension and diabetes for whom body-composition data (bio-electrical impedance analysis and anthropometry) were available. Serum leptin concentrations were more than four times higher in women than in men (18.5 +/- 13.9 compared with 3.8 +/- 3.6 ng/L, P < 0.0001). In individuals with comparable body mass indexes, these differences persisted after adjustment for either percentage fat (P < 0.05) or fat mass (P < 0.0001) by multivariate-regression analysis. After fat mass was adjusted for, the serum leptin concentration in both men and women was independent of waist circumference but in women was associated with hip circumference. Hip circumference is a proxy measure of peripheral fat and these results suggest that the larger hips of women may contribute to the sex difference in serum leptin concentration.     

Manipulations of germ-cell populations in the gonad of the fowl

Prehistoric populations suffered the rigors of everyday survival as hunter-gatherers, and some of the individuals had osseous manifestations as a result both of these stresses and of aging. Paleomedical scientists usually seek out osseous abnormalities found in skeletal remains, thus stressing the morbidity of a population [4]. In so doing, they portray those populations as less healthy than their own. This may not necessarily be the case. Specimens without signs of injury should be considered as evidence of the population's vitality; bones with evidence of injury that has healed during life should be considered as evidence of debility; and bones with evidence of conditions that are occupational in origin should be considered as evidence of social, economic, and ecological environmental conditions [4]. This is more useful than singling out specimens with abnormalities as signs of the population's morbidity [4]. This is confirmed by the majority of bones appearing osteologically healthy, except for the characteristic findings of biomechanical wear and tear arising from acquiring food and from combat (osteoarthritis, fractures). Although a number of children may have been infected by the treponematoses, which were manifested by cutaneous lesions, only a small percentage of children actually experienced osseous infection. Also, bone metastases were extremely rare.