Palaeohistology and life history evolution in cave bears, Ursus spelaeus sensu lato.

The abundance of skeletal remains of cave bears in Pleistocene deposits can offer crucial information on the biology and life history of this megafaunal element. The histological study of 62 femora from 23 different European localities and comparisons with specimens of five extant ursid species revealed novel data on tissue types and growth patterns. Cave bear's femoral bone microstructure is characterized by a fibrolamellar complex with increasing amounts of parallel-fibered and lamellar bone towards the outer cortex. Remodelling of the primary bone tissue initially occurs close to the perimedullary margin of the bone cortex around the linea aspera. Although similar histological traits can be observed in many extant bear species, the composition of the fibrolamellar complex can vary greatly. Cave bears reached skeletal maturity between the ages of 10 and 14, which is late compared to other bear species. There is a significant correlation between altitude and growth, which reflects the different body sizes of cave bears from different altitudes.

Scaling effect on the mid-diaphysis properties of long bones-the case of the Cervidae (deer).

How skeletal elements scale to size is a fundamental question in biology. While the external shape of long bones was intensively studied, an important component of their organization is also found in their less accessible inner structure. Here, we studied mid-diaphyseal properties of limb long bones, characterizing notably the thickness of their cortices (bone walls), in order to test whether body size directly influences bone inner organization. Previous examinations of scaling in long bones used broad samplings to encompass a wide range of body sizes. To account for the effect of confounding factors related to different lifestyles, we focused our comprehensive sampling on a mammalian clade that comprises various body sizes but a relatively uniform lifestyle, the Cervidae. Positive allometry was found in femoral cross-sectional shape, indicating greater directional bending rigidity in large-sized taxa. None of the compactness parameters scaled allometrically in any of their bones. The cortices of sampled zeugopodial bones (tibia and radius) were found as significantly thicker than those of stylopodial bones (femur and humerus). Furthermore, while the mean relative cortical thickness values for both stylopodial and zeugopodial bones are close to mass-saving optima, the variance for the stylopodial bones is significantly lower. This suggests that mass saving is less intensively selected in zeugopodial bones. Finally, the long-legged Elk (Alces) and the short-legged dwarf Cretan deer (Candiacervus) featured rather thin and thick cortices, respectively, suggesting that the acquisition of a different limb proportion is accompanied by a modification of the relative mid-diaphyseal cortical thickness.

The impact of weight loss and low BMI on mortality of nursing home residents - Results from the nutritionDay in nursing homes.

BACKGROUND: Weight loss and low body-mass-index (BMI) are well-known risk factors for mortality among older persons. Both items represent a reduced nutritional state but their nature is different. It is, however, unclear which of these factors is more important for prognosis and if there is interference or interaction between them. OBJECTIVE: To measure the prevalence of low BMI and weight loss in nursing home residents and to analyze their impact on mortality. METHODS: The nutritionDay in nursing homes is an international annual one-day cross sectional survey evaluating malnutrition and 6-months mortality. The data collected from 2007 to 2012 were analyzed. The mortality risk due to a BMI <20 kg/m(2) and weight loss >5 kg was calculated by logistic regression analysis with adjustment for confounding factors. RESULTS: In total, 10,298 residents with a mean age of 85 years (78% female) from 191 nursing homes in 13 countries were included in the analysis. Eighteen percent (17.7%) had a low BMI < 20 kg/m(2), and 11.3% lost > 5 kg of body weight in the previous year. Low BMI <20 kg/m(2) and weight loss >5 kg were both independent and significant risk factors for 6-months mortality (OR 1.7 and 1.5; p < 0.001 in the adjusted model). In comparison to the effect size of low BMI and weight loss alone, the interaction of both factors was substantial (OR = 1.4; p = 0.056). The average 6-months mortality was 13.8%. Subjects with BMI ≥20 kg/m(2) without weight loss >5 kg presented the lowest mortality of 11.2%. In subjects with one of the two features, weight loss >5 kg or low BMI <20 kg/m(2), mortality was significantly increased to 17.4% and 19.8%, respectively. However, if both features were present simultaneously the mortality increased disproportionally to 35.7% (OR 3.5; p < 0.001). In addition, this study presents an overlap and a strong dose-effect relationship of both items with regard to the 6-month mortality. CONCLUSION: A BMI <20 kg/m(2) and weight loss >5 kg in one year are both independent and equally relevant risk factors for the 6-months mortality of nursing home residents aged 65 years or older. For this reason weight loss should be avoided and residents with a low BMI and weight loss should receive particular attention and nutritional care.

Evaluating Nonverbal Behavior of Individuals with Dementia During Feeding: A Survey of the Nursing Staff in Residential Care Homes for Elderly Adults.

OBJECTIVES: To determine how nursing staff evaluate nonverbal behavior related to hand and tube feeding of residents with dementia. DESIGN: Cross-sectional survey. SETTING: A stratified sample of nurses and nursing assistants in residential nursing homes in a major German city. PARTICIPANTS: Nursing staff members (N = 131) in 12 nursing homes. MEASUREMENTS: Nursing staff perception of nonverbal behavior of residents with dementia in response to hand and tube feeding. RESULTS: Ninety-three percent of survey participants considered the nonverbal behavior of residents with advanced dementia crucial for decisions about artificial nutrition and hydration (ANH). The same percentage had at some point encountered residents who did not open their mouths when feeding was attempted. Fifty-three percent of the participants interpreted residents' expressions of pleasure while eating as a will to live. The most frequent interpretation of residents' aversive behavior was discomfort. When residents did not open their mouth during nurse's hand feeding, 41% of the participants inferred a will to die. CONCLUSION: Most nurses and nursing assistants consider residents' behavior during hand or tube feeding to be important, but their interpretations are heterogeneous. Various professional caregivers assume a will to live or die. Further reflection is necessary to determine how behavioral expressions should be factored into treatment decisions.

Mammalian bone palaeohistology: a survey and new data with emphasis on island forms.

The interest in mammalian palaeohistology has increased dramatically in the last two decades. Starting in 1849 via descriptive approaches, it has been demonstrated that bone tissue and vascularisation types correlate with several biological variables such as ontogenetic stage, growth rate, and ecology. Mammalian bone displays a large variety of bone tissues and vascularisation patterns reaching from lamellar or parallel-fibred to fibrolamellar or woven-fibred bone, depending on taxon and individual age. Here we systematically review the knowledge and methods on cynodont and mammalian bone microstructure as well as palaeohistology and discuss potential future research fields and techniques. We present new data on the bone microstructure of two extant marsupial species and of several extinct continental and island placental mammals. Extant marsupials display mainly parallel-fibred primary bone with radial and oblique but mainly longitudinal vascular canals. Three juvenile specimens of the dwarf island hippopotamid Hippopotamus minor from the Late Pleistocene of Cyprus show reticular to plexiform fibrolamellar bone. The island murid Mikrotia magna from the Late Miocene of Gargano, Italy displays parallel-fibred primary bone with reticular vascularisation and strong remodelling in the middle part of the cortex. Leithia sp., the dormouse from the Pleistocene of Sicily, is characterised by a primary bone cortex consisting of lamellar bone and a high amount of compact coarse cancellous bone. The bone cortex of the fossil continental lagomorph Prolagus oeningensis and three fossil species of insular Prolagus displays mainly parallel-fibred primary bone and reticular, radial as well as longitudinal vascularisation. Typical for large mammals, secondary bone in the giant rhinocerotoid Paraceratherium sp. from the Late Oligocene of Turkey is represented by dense Haversian bone. The skeletochronological features of Sinomegaceros yabei, a large-sized deer from the Pleistocene of Japan closely related to Megaloceros, indicate a high growth rate. These examples and the synthesis of existing data show the potential of bone microstructure to reveal essential information on life history evolution. The bone tissue and the skeletochronological data of the sampled island species suggest the presence of various modes of bone histological modification and mammalian life history evolution on islands to depend on factors of island evolution such as island size, distance from mainland, climate, phylogeny, and time of evolution.

Growth in fossil and extant deer and implications for body size and life history evolution.

BACKGROUND: Body size variation within clades of mammals is widespread, but the developmental and life-history mechanisms by which this variation is achieved are poorly understood, especially in extinct forms. An illustrative case study is that of the dwarfed morphotypes of Candiacervus from the Pleistocene of Crete versus the giant deer Megaloceros giganteus, both in a clade together with Dama dama among extant species. Histological analyses of long bones and teeth in a phylogenetic context have been shown to provide reliable estimates of growth and life history patterns in extant and extinct mammals. RESULTS: Similarity of bone tissue types across the eight species examined indicates a comparable mode of growth in deer, with long bones mainly possessing primary plexiform fibrolamellar bone. Low absolute growth rates characterize dwarf Candiacervus sp. II and C. ropalophorus compared to Megaloceros giganteus displaying high rates, whereas Dama dama is characterized by intermediate to low growth rates. The lowest recorded rates are those of the Miocene small stem cervid Procervulus praelucidus. Skeletal maturity estimates indicate late attainment in sampled Candiacervus and Procervulus praelucidus. Tooth cementum analysis of first molars of two senile Megaloceros giganteus specimens revealed ages of 16 and 19 years whereas two old dwarf Candiacervus specimens gave ages of 12 and 18 years. CONCLUSIONS: There is a rich histological record of growth across deer species recorded in long bones and teeth, which can be used to understand ontogenetic patterns within species and phylogenetic ones across species. Growth rates sensu Sander & Tückmantel plotted against the anteroposterior bone diameter as a proxy for body mass indicate three groups: one with high growth rates including Megaloceros, Cervus, Alces, and Dama; an intermediate group with Capreolus and Muntiacus; and a group showing low growth rates, including dwarf Candiacervus and Procervulus. Dwarf Candiacervus, in an allometric context, show an extended lifespan compared to other deer of similar body size such as Mazama which has a maximum longevity of 12 years in the wild. Comparison with other clades of mammals reveals that changes in size and life history in evolution have occurred in parallel, with various modes of skeletal tissue modification.

A new look at ichthyosaur long bone microanatomy and histology: implications for their adaptation to an aquatic life.

BACKGROUND: Ichthyosaurs are Mesozoic reptiles considered as active swimmers highly adapted to a fully open-marine life. They display a wide range of morphologies illustrating diverse ecological grades. Data concerning their bone microanatomical and histological features are rather limited and suggest that ichthyosaurs display a spongious, "osteoporotic-like" bone inner structure, like extant cetaceans. However, some taxa exhibit peculiar features, suggesting that the analysis of the microanatomical and histological characteristics of various ichthyosaur long bones should match the anatomical diversity and provide information about their diverse locomotor abilities and physiology. METHODOLOGY/PRINCIPAL FINDINGS: The material analyzed for this study essentially consists of mid-diaphyseal transverse sections from stylopod bones of various ichthyosaurs and of a few microtomographic (both conventional and synchrotron) data. The present contribution discusses the histological and microanatomical variation observed within ichthyosaurs and the peculiarities of some taxa (Mixosaurus, Pessopteryx). Four microanatomical types are described. If Mixosaurus sections differ from those of the other taxa analyzed, the other microanatomical types, characterized by the relative proportion of compact and loose spongiosa of periosteal and endochondral origin respectively, seem to rather especially illustrate variation along the diaphysis in taxa with similar microanatomical features. Our analysis also reveals that primary bone in all the ichthyosaur taxa sampled (to the possible exception of Mixosaurus) is spongy in origin, that cyclical growth is a common pattern among ichthyosaurs, and confirms the previous assumptions of high growth rates in ichthyosaurs. CONCLUSIONS/SIGNIFICANCE: The occurrence of two types of remodelling patterns along the diaphysis, characterized by bone mass decrease and increase respectively is described for the first time. It raises questions about the definition of the osseous microanatomical specializations bone mass increase and osteoporosis, notably based on the processes involved, and reveals the difficulty in determining the true occurrence of these osseous specializations in ichthyosaurs.