Sex difference in distribution and iron responsiveness of the two ferritins of rat cardiac and skeletal muscle

The presence of two electrophoretically and structurally distinguishable forms of ferritin (“fast” and “slow”) in cardiac and skeletal muscle (diaphragm) of the rat was confirmed. Although the total amount of cardiac ferritin showed no difference in concentration in male and female rats, the distribution between the fast and slow species was remarkedly different in the two sexes, the fast form predominating in the cardiac muscle and diaphragm of the female. In agreement with this, the rates of synthesis and of degradation of the fast species were greater in teh female, while the opposite obtained for the male. Iron administration stimulated synthesis of each ferritin species in the cardiac muscle and diaphragm of both sexes. Induction of cardiac connective tissue hypertrophy with isoproterenol inverted the ratio of slow to fast ferritin in female rats, while iron adminsitration along with isoproterenol restored this to normal. It is concluded that the metabolism of ferritin in cardiac and skeletal muscle is sensitive both to sexual status and to iron administration.     

Permanent lip augmentation employing polytetrafluoroethylene grafts.

There is a paucity of literature regarding aesthetic enhancement of the lips. This is due to the lack of reliable techniques employing autogenous tissue and the reluctance on the part of surgeons to use an alloplastic implant in this anatomic region, which is superficial, subject to trauma, and must conform to innumerable geometric shapes. The ideal lip augmentation procedure should provide for a predictable, permanent enlargement without visible scars or donor-site deformity, can be customized to the particular patient's anatomy, and can be reversed if so desired. A series of 21 alloplastic lip implants employing polytetrafluoroethylene with a mean follow-up of 14.33 months is presented. The overall complication rate was 9.52 percent. Permanent lip augmentation can be achieved with alloplastic sheet grafts of polytetrafluoroethylene in a safe and predictable fashion. Stiffness of the lips develops with progressive thickness of the grafts. Grafts exceeding 3 mm in thickness should be avoided.     

Geographic range structure in North American landbrids: variation with migratory strategy, trophic level, and breeding habitat

We investigated the relationship between abundance and geographic range structure of 258 North American landbirds. For this purpose we used six measures of range structure based upon fractal geometry and geostatistics, and three ecological characteristics that can influence avian distribution. Permanent residents (PRs) that were abundant showed little fragmentation of their abundance surface at the periphery of their breeding range. Conversely, common Neotropical migrants (NTMs) exhibited low fragmentation of their central populations the abundance surface was smoother for PRs than NTMs or short-distance migrants (SDMs). indicating that changes in abundance occurred more gradually across space for this group. The areas of high abundance for grassland species had little demographic fragmentation, but other populations showed little spatial autocorrelation in abundance. Species that bred in late-successional forests were relatively rare compared to species breeding in other habitat types. Among carnivores. PRs had a higher average abundance than either NTMs or SDMs. Although carnivores had more distributional gaps within their ranges than other trophic groups, the number of gaps did not differ between rare and abundant species, indicating that increased abundance did not change their presence. absence distribution maps. Knowledge of patterns and variations of geographic range structure among species may provide insights into processes that shape and maintain the biodiversity of a continent.     

Modeling mechanical inhomogeneities in small populations of proliferating monolayers and spheroids

Understanding the mechanical behavior of multicellular monolayers and spheroids is fundamental to tissue culture, organism development, and the early stages of tumor growth. Proliferating cells in monolayers and spheroids experience mechanical forces as they grow and divide and local inhomogeneities in the mechanical microenvironment can cause individual cells within the multicellular system to grow and divide at different rates. This differential growth, combined with cell division and reorganization, leads to residual stress. Multiple different modeling approaches have been taken to understand and predict the residual stresses that arise in growing multicellular systems, particularly tumor spheroids. Here, we show that by using a mechanically robust agent-based model constructed with the peridynamic framework, we gain a better understanding of residual stresses in multicellular systems as they grow from a single cell. In particular, we focus on small populations of cells (1–100 s) where population behavior is highly stochastic and prior investigation has been limited. We compare the average strain energy density of cells in monolayers and spheroids using different growth and division rules and find that, on average, cells in spheroids have a higher strain energy density than cells in monolayers. We also find that cells in the interior of a growing spheroid are, on average, in compression. Finally, we demonstrate the importance of accounting for stochastic fluctuations in the mechanical environment, particularly when the cellular response to mechanical cues is nonlinear. The results presented here serve as a starting point for both further investigation with agent-based models, and for the incorporation of major findings from agent-based models into continuum scale models when explicit representation of individual cells is not computationally feasible.     

Water availability,fundamental niches and realized niches: A case study from the Cape flora

The ability of plants to survive drought or waterlogging constitutes an important niche parameter, which might be particularly significant in explaining species coexistence in the species‐rich and seasonally dry Cape Floristic Region of South Africa. However, the degree of physiological adaptation and specialization to these eco‐hydrological parameters (the fundamental niche) cannot be readily inferred from correlative studies based on species distributions and spatial variation in environmental parameters (the realized niche). We used an ex situ greenhouse experiment to compare the fundamental hydrological niches (different mean annual precipitation, rainfall seasonality and soil drainage) of six eco‐hydrologically divergent African Restionaceae species. Juvenile plants were subjected to six different watering treatments, ranging from no watering to waterlogging, to determine drought and waterlogging susceptibility and optimal growth conditions. We used the rate of biomass accumulation and survival rate as response measures. We found that species from dry and mesic (but well‐drained) habitats had optimal or near‐optimal growth at benign conditions (under which most restio species grow well). All species performed worse when droughted and died when not watered. Species from dry habitats tended to perform better (assessed in growth) than species from wet habitats under droughting. Species from wet habitats performed best when waterlogged, whereas species from dry habitats performed very poorly when waterlogged – thus showing that realized and fundamental niches covaried at the wet end of the hydrological gradient. We conclude that eco‐hydrological parameters are part of the fundamental niche, and fundamental and realized species niches are approximately correlated along them. The distribution of wet habitat species appears not to reflect their drought tolerance, suggesting that it may not be predicted by bioclimatic variables, but rather by soil drainage characteristics.