Comparative analysis of dermal collagen and lipids in cereblon ablated mice using a multimodal nonlinear optical system

By utilizing a multimodal nonlinear optical system that combines coherent anti-Stokes Raman scattering and second harmonic generation to investigate biological characteristics of dermal tissues ex vivo, we demonstrate the potential feasibility of using this optical approach as a powerful new investigative tool for future biomedical research. For this study, our optical system was utilized for the first time to analyze lipid and collagen profiles in cereblon knockout (KO) mouse skin, and we were able to discover significant alterations in the number of carbon–carbon double bonds (wild-type vs. cereblon KO; N_CC: 0.75 vs. 0.85) of skin fatty acids in triacylglycerides as well as changes in dermal collagen fibers (25% reduction in cereblon KO). By adopting our optical system to biological studies, we provide researchers with another diagnostic approach to validate their experimental results, which will significantly advance the state of biomedical research.     

Pressure-sensitive nutrient consumption via dynamic normal stress in rotational bioreactors

Pressure-sensitive biological response is simulated in “rotating-cup” bioreactors with unidirectional modulations in compressive stress at the cylindrical wall that stimulate bone-tissue growth. Anchorage-dependent mammalian cells (i) adhere to a protein coating, (ii) receive nutrients and oxygen from an aqueous medium via radial diffusion toward the active surface, and (iii) respond to physiological modulations in centrifual-force-induced fluid pressure at the cell/aqueous-medium interface. This process is modeled by the classic diffusion equation (i.e., Fick's second law), with a time-dependent reaction/diffusion boundary condition at the wall. Non-reversing angular velocity modulations resemble pulsations at physiological frequencies. Computer simulations of nutrient consumption profiles suggest that rotational bioreactor designs should consider the effects of normal stress when the pressure-sensitive Damköhler number (i.e., ratio of the pressure-dependent zeroth-order rate of nutrient consumption relative to the rate of nutrient diffusion toward active cells adhered to the cylindrical wall), evaluated under steady rotation, is greater than ≈ 10–20% of the stress-free Damköhler number (i.e., β_0,1st-order = 0.025) for simple 1st-order stress-free kinetics, and ≈ 1% of the stress-free Damköhler number (i.e., β_0,2nd-order = 0.40) for complex 2nd-order stress-free nutrient consumption. When the peak-to-peak amplitude of angular velocity modulations of the cylindrical wall is the same as or larger than the angular velocity for steady rotation, the effect of non-reversing centrifugal-force-induced dynamic normal stress in rotational bioreactors, superimposed on steady rotation, can be significant when one is below the critical value of the pressure-sensitive Damköhler number that has been identified under steady rotation.     

Co-existence between receptors,carriers, and second messengers on astrocytes grown in primary cultures

This overview deals with the current important problem of the expression by astrocytes of a set of funtional and neurochemical properties which, until a few years ago, were thought to be specific for neurons. The interaction of different receptor functions and carrier systems in astrocytes and the functional importance of second messenger systems is discussed.     

Mineral content of calcified tissues in cystic fibrosis mice

Although abnormal hard tissue mineralization is a recognized complication of cystic fibrosis (CF), the pathogenesis leading from the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein is poorly understood. We hypothesized that CFTR plays a direct role in the mineralization of bone and teeth and tested the hypothesis using CF mouse models [CFTR(−) mice]. In vivo measurements by dual-emission X-ray absorpitometry (DEXA) indicated that bone mineral density (BMD) was reduced in CF mice as compared to gender-matched littermates. However, no change was evident after correction of BMD for the covariant of body weight. The latter finding was confirmed in isolated femurs and nasal bones by standard dry-ashing and instrumental neutron activation analysis (INAA). INAA of the continuously growing hypsodont incisor teeth from CFTR(−) mice revealed reduced Ca and normal P in the enamel layer—a finding consistent with changes in the deciduous teeth of CF children. Interestingly, enamel fluoride was increased in the CFTR(−) incisors and may associate with abnormal enamel crystallite formation. The iron content of the incisor enamel was reduced, explaining the loss of yellow pigmentation in CFTR(−) incisors. In contrast to the incisors, the mineral content of the slow-growing brachydont molar teeth was not different between CFTR(−) and CFTR(+) mice. It was concluded that CFTR does not play a direct role in the mineralization of bones or brachydont teeth in mice. Functional CFTR is apparently required for normal mineralization of the hypsodont incisors. However, multiple changes in the mineral composition of the CF incisors suggest an indirect role for CFTR, perhaps by maintaining a normal salivary environment for continuous tooth eruption. Preliminary reports published in Pediatric Pulmonology, 14, 253A (1997) and 15, 253A (1998).     

Contributions to the Biomechanics of Plants. I. Stabilities of Plant Stems with Strengthening Elements of Different Cross-Sections Against Weight and Wind Forces*

Biophysical considerations allow estimates of the mechanical stresses on self-bearing vertical stems of plants. Even at moderate wind velocities the stresses induced by aerodynamic forces dominate over those induced by the own weight. Using polar coordinates, analytical expressions of cross-sectional area and axial second moment of area for centrisymmetric structures with symmetries threefold or higher are derived. Calculating the relative section modulus for various (centrisymmetric) arrangements of stabilizing structures leads to an estimate of the “mechanical effectivity” of these structures. If for plant stems, seen as composite materials, the second moments of area and the elastic moduli are known, the contribution of the different tissues to mechanical stability can be determined quantitatively. The mechanical design of early “vascular” land plants and of stems of (fossil) trees and lianas in different ontogenetic stages can be assessed.     

Physiological factors regulating polyandry in Lobesia botrana (Lepidoptera: Tortricidae)

Abstract. The effects of several physiological factors related to female multiple mating in the monandrous Lobesia botrana Denis and Schiffermuller (Lepidoptera: Tortricidae) were studied under laboratory conditions. Polyandry was assessed observing the induction of re-calling in previously once-mated females. Female age at first mating had no effect on induction of re-calling during practically the whole of the female lifetime, but in older females it was significantly lower. The percentage of re-calling was negatively correlated with the volume of the spermatophore received, ranging from ≅ 23% with the largest spermatophores to ≅ 75% with the smallest ones. Furthermore, the smaller the spermatophore volume, the earlier the re-calling was induced, significantly reducing die female refractory period after the first mating. Heavy females showed a significantly higher rate of re-calling (52.8%) than light ones (37.0%), but no differences were observed when females received only small spermatophores. This finding was explained by die allometric relationship between me female weight and the size of its reproductive system that affects relative replenishment by the spermatophore. Females with a supply of water displayed a significantly higher rate of re-calling (41.2%) than control females (22.8%), highlighting the effect of adult feeding (or drinking) status on the re-calling behaviour. The short-distance presence of virgin males with once-mated females promoted a re-calling rate (and subsequent matings) close to 37%, significantly higher than that of isolated females (20%). It is concluded mat re-calling and polyandry in L. botrana are controlled, as expected, by a number of mating-derived stimuli, but also to a great extent by other physiological stimuli unrelated to mating. The reproductive strategies in relation to polyandry and the mechanisms controlling female sexual inhibition are discussed.