Cell behavior on 2-D
in vitro
cultures is continually being improved to better mimic
in vivo
physiological conditions by combining niche cues including multiple cell types and substrate stiffness, ...which are well known to impact cell phenotype. However, no system exists in which a user can systematically examine cell behavior on a substrate with a specific stiffness (elastic modulus) in culture with a different cell type, while maintaining distinct cell populations. We demonstrate the modification of a silicon reconfigurable co-culture system with a covalently linked hydrogel of user-defined stiffness. This device allows the user to control whether two separate cell populations are in contact with each other or only experience paracrine interactions on substrates of controllable stiffness. To illustrate the utility of this device, we examined the role of substrate stiffness combined with myoblast co-culture on adipose derived stem cell (ASC) differentiation and found that the presence of myoblasts and a 10 kPa substrate stiffness increased ASC myogenesis
versus
co-culture on stiff substrates. As this example highlights, this technology better controls the
in vitro
microenvironment, allowing the user to develop a more thorough understanding of the combined effects of cell-cell and cell-matrix interactions.
We advance a co-culture device that allows the user to tune the stiffness of the substrate to simultaneously monitor both cell-cell and cell-matrix interactions in 2-D
in vitro
culture.
Observations (0–8 km) from the Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiment are analyzed to examine air masses contributing to the observed variability of springtime O
3
...and its seasonal increase at 40°–85°N over North America. Factor analysis using the positive matrix factorization and principal component analysis methods is applied to the data set with 14 chemical tracers (O
3
, NO
y
, PAN, CO, CH
4
, C
2
H
2
, C
3
H
8
, CH
3
Cl, CH
3
Br, C
2
Cl
4
, CFC‐11, HCFC‐141B, Halon‐1211, and
7
Be) and one dynamic tracer (potential temperature). Our analysis results are biased by the measurements at 5–8 km (70% of the data) due to the availability of
7
Be measurements. The identified tracer characteristics for seven factors are generally consistent with the geographical origins derived from their 10 day back trajectories. Stratospherically influenced air accounts for 14 ppbv (35–40%) of the observed O
3
variability for data with O
3
concentrations <100 ppbv at middle and high latitudes. It accounts for about 2.5 ppbv/month (40%) of the seasonal O
3
trend at midlatitudes but for only 0.8 ppbv/month (<20%) at high latitudes, likely reflecting more vigorous midlatitude dynamical systems in spring. At midlatitudes, reactive nitrogen‐rich air masses transported through Asia are much more significant (11 ppbv in variability and 3.5 ppbv/month in trend) than other tropospheric contributors. At high latitudes the O
3
variability is significantly influenced by air masses transported from lower latitudes (11 ppbv), which are poor in reactive nitrogen. The O
3
trend, in contrast, is largely defined by air masses rich in reactive nitrogen transported through Asia and Europe across the Pacific or the Arctic (3 ppbv/month). The influence from the stratospheric source is more apparent at 6–8 km, while the effect of O
3
production and transport within the troposphere is more apparent at lower altitudes. The overall effect of tropospheric photochemical production, through long‐range transport, on the observed O
3
variability and its seasonal trend is more important at high latitudes relative to more photochemically active midlatitudes.
Recent improvements in the energy resolution of resonant inelastic x-ray scattering experiments (RIXS) at the Cu-L\(_3\) edge have enabled the study of lattice, spin, and charge excitations. Here, we ...report on the detection of a low intensity signal at 140meV, twice the energy of the bond-stretching (BS) phonon mode, in the cuprate superconductor \(\textrm{Bi}_2\textrm{Sr}_2\textrm{Ca}\textrm{Cu}_2\textrm{O}_{8+x}\) (Bi-2212). Ultra-high resolution polarimetric RIXS measurements allow us to resolve the outgoing polarization of the signal and identify this feature as a two-phonon excitation. Further, we study the connection between the two-phonon mode and the BS one-phonon mode by constructing a joint density of states toy model that reproduces the key features of the data.
Intercellular communication via gap junctions, as measured by dye and electrical coupling, disappears within 12 h in primary rat hepatocytes cultured in serum-supplemented media or within 24 h in ...cells in a serum-free, hormonally defined medium (HDM) designed for hepatocytes. Glucagon and linoleic acid/BSA were the primary factors in the HDM responsible for the extended life span of the electrical coupling. After 24 h of culture, no hormone or growth factor tested could restore the expression of gap junctions. After 4-5 d of culture, the incidence of coupling was undetectable in a serum-supplemented medium and was only 4-5% in HDM alone. However, treatment with glycosaminoglycans or proteoglycans of 24-h cultures, having no detectable gap junction protein, resulted in synthesis of gap junction protein and of reexpression of electrical and dye coupling within 48 h. Most glycosaminoglycans were inactive (heparan sulfates, chondroitin-6 sulfates) or only weakly active (dermatan sulfates, chondroitin 4-sulfates, hyaluronates), the weakly active group increasing the incidence of coupling to 10-30% with the addition of 50-100 μg/ml of the factor. Treatment of the cells with 50-100 μg/ml of heparins derived from lung or intestine resulted in cells with intermediate levels of coupling (30-50%). By contrast, 10-20 μg/ml of chondroitin sulfate proteoglycan, dermatan sulfate proteoglycan, or liver-derived heparin resulted in dye coupling in 80-100% of the cells, with numerous cells showing dye spread from a single injected cell. Sulfated polysaccharides of glucose (dextran sulfates) or of galactose (carrageenans) were inactive or only weakly active except for lambda-carrageenan, which induced up to 70% coupling (albeit no multiple coupling in the cultures). The abundance of mRNA (Northern blots) encoding gap junction protein and the amounts of the 27-kD gap junction polypeptide (Western blots) correlated with the degree of electrical and dye coupling indicating that the active glycosaminoglycans and proteoglycans are inducing synthesis and expression of gap junctions. Thus, proteoglycans and glycosaminoglycans, especially those found in abundance in the extracellular matrix of liver cells, are important in the regulation of expression of gap junctions and, thereby, in the regulation of intercellular communication in the liver. The relative potencies of heparins from different tissue sources at inducing gap junction expression are suggestive of functional tissue specificity for these glycosaminoglycans.
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A linkage study of bipolar illness Berrettini, W H; Ferraro, T N; Goldin, L R ...
Archives of general psychiatry
54, Issue:
1
Journal Article
Although genetic epidemiological studies of bipolar (BP) illness are consistent with a heritable component, inherited risk factors remain unknown. The goal of the present study is to describe the ...localization of BP susceptibility loci through linkage strategies, including a genome-wide search.
A linkage study of 22 BP families has been performed. These BP families include almost 400 persons, 173 of whom have been diagnosed as having BP I, schizoaffective, BP II with major depression, or recurrent unipolar illness. Using an autosomal dominant disease model with 85% or 50% age-dependent penetrance, and a recessive model with 85% penetrance, linkage analyses were performed assuming a narrow (BP and schizoaffective) or a broad (BP, schizoaffective, or unipolar) definition of the BP spectrum. Affected sibling pairs and affected pedigree member analyses were performed when positive lod scores were observed in multiple pedigrees. The present article describes linkage analysis of 310 DNA markers on chromosomes 1, 5p, 6, 8, 10q, 11q, and 12 to 18.
None of the loci examined disclosed compelling evidence for linkage using lod score analyses. Model-independent analysis by multilocus affected pedigree member method in the pericentromeric chromosome 18 region disclosed statistically significant evidence (P < .0001) for a BP susceptibility gene in this region. Multilocus analysis by affected sibling pair method also disclosed evidence for linkage (P < .00008).
Our results imply that a BP susceptibility gene exists near the centromere of chromosome 18. Confirmation of this finding (by independent investigators studying different pedigrees) has been published, suggesting that a valid BP disease linkage may have been discovered.
Chromosome 5 markers spanning the pter to the qter were used to examine linkage to bipolar illness in 14 pedigrees. Twenty-four loci were examined in 237 individuals, of whom 69 were either bipolars ...or schizoaffectives. Marker genotypes were determined for each individual and lod scores were calculated under a dominant disease model with a maximum penetrance of 85%, a disease gene frequency of 0.015, a variable age of onset, and a phenocopy rate of 0.001. Under the assumption that bipolar illness is genetically homogeneous, the total lod scores from all pedigrees with each marker were uniformly lower than -2.0, suggesting the absence of linkage to disease at any of these loci. Multipoint analysis allowed exclusion of intervals between markers. When lod scores were calculated allowing for heterogeneity, no subset of linked families was found. These results indicate that in our pedigree series almost the entire mapped region of chromosome 5 can be excluded for linkage to bipolar illness.
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