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At least 163 records · Page 9Linked to original sources
PubMed2001

Redox state of Mars' upper mantle and crust from Eu anomalies in shergottite pyroxenes.

The oxidation state of basaltic martian meteorites is determined from the partitioning of europium (Eu) in their pyroxenes. The estimated redox conditions for these samples correlate with their initial neodymium and strontium isotopic compositions. This is interpreted to imply varying degrees of interaction between the basaltic parent melts, derived from a source in the martian mantle, and a crustal component. Thus, the mantle source of these martian basalts may have a redox state close to that of the iron-wüstite buffer, whereas the martian crust may be more oxidized (with a redox state higher than or equal to that of the quartz-fayalite-magnetite buffer). A difference in redox state of more than 3 log units between mantle and crustal reservoirs on Mars could result from oxidation of the crust by a process such as aqueous alteration, together with a subsequent lack of recycling of this oxidized crust through the reduced upper mantle.

Europium↗
PubMed2000

Field measurement of slow metamorphic reaction rates at temperatures of 500 degrees to 600 degrees C

High-temperature metamorphic reaction rates were measured using strontium isotopic ratios of garnet and whole rock from a field site near Simplon Pass, Switzerland. For metamorphic conditions of cooling from 612 degrees +/- 17 degrees C to 505 degrees +/- 15 degrees C at pressures up to 9.1 kilobars, the inferred bulk fluid-rock exchange rate is 1.3(-0.4)(+1.1) x 10(-7) grams of solid reacted per gram of solid per year, several orders of magnitude lower than laboratory-based estimates. The inferred reaction rate suggests that mineral chemistry may lag the evolving conditions in Earth's crust during mountain building.

Journal Article↗
PubMed1993

Macrophage heterogeneity in development and differentiation.

Macrophages, which are heterogeneous populations existing in various tissues and organs, are responsible for numerous metabolic, immunological, and inflammatory processes in physiological and pathological conditions. Macrophage heterogeneity is observed from early ontogeny. Primitive macrophages first develop in yolk sac hematopoiesis, by-passing the differentiation pathway of the monocytic series to differentiate into fetal macrophages in various tissues. Monocytic cells are a minor cell population in the early fetal period, and increase in the late stage. Primitive/fetal macrophages proliferate and survive in loco in the fetal period and reside as resident macrophages after birth. In adult animals, monocytes are differentiated from promonocytes derived from pluripotent stem cells in bone marrow. Monocytes exude in inflammatory foci and differentiate into exudate macrophages, exudate-resident macrophages and peroxidase-negative macrophages, but not resident macrophages. Monocyte-derived macrophages are a short-lived and non-proliferating cell population. Tissue (resident) macrophages proliferate and maintain their population by self renewal. In mice rendered monocytopenic by administration of a bone-seeking isotope, strontium-89, tissue resident macrophages maintained their population for 6 weeks. Resident macrophages in the liver formed glucan-induced granulomas in this monocytopenic model. In macrophage colony stimulating factor (M-CSF)-deficient mice (op/op), monocytes as well as tissue macrophages are deficient. However, M-CSF-independent tissue macrophages and Langerhans/dendritic cells are present in the defective condition of monocyte differentiation into macrophages, indicating that differentiation pathways of tissue macrophages and nonlymphoid dendritic cells are different from those of monocytes. In cultures supplemented with various colony stimulating factors (CSFs), heterogenous macrophage populations were generated. These in vivo and in vitro findings suggest that the phenotypic and functional heterogeneity of macrophages reflects complex macrophage differentiation mechanisms and that CSFs are important factors in the formation of a microenvironment for macrophage differentiation.

Aging↗
PubMed1985

The osteoinductive capacity of differently HCl-decalcified bone alloimplants.

Three procedures to obtain bone inductive implants were tested heterotopically in 3-month-old allogeneic rats: 1) antigen-extracted HCl-decalcified at 4 degrees C, autolysed implant (AAA bone); 2) HCl-decalcified implant at 4 degrees C; 3) HCl-decalcified implant at room temperature. Each type of implant was either deep-frozen at -35 degrees C for at least 2 months or immediately freeze-dried. The bone inductive capacity of the differently HCl-decalcified cortical bone implant was evaluated at 2 months by isotopic strontium incorporation and by ash-weight measurements. Bone HCl-decalcification alone, either at 4 degrees C or at room temperature, gave a higher new bone yield than the freeze-dried AAA bone. The type or short-term preservation technique had no effect on the osteoinductive capacity of either of the differently treated implants, AAA bone expected.

Animals↗
PubMed1976

Bone scintiscanning updated.

Use of modern materials and methods has given bone scintiscanning a larger role in clinical medicine, The safety and ready availability of newer agents have led to its greater use in investigating both benign and malignant disease of bone and joint. Present evidence suggests that abnormal accumulation of 99mTc-polyphosphate and its analogues results from ionic deposition at crystal surfaces in immature bone, this process being facilitated by an increase in bone vascularity. There is, also, a component of matrix localization. These factors are in keeping with the concept that abnormal scintiscan sites represent areas of increased osteoblastic activity, although this may be an oversimplification. Increasing evidence shows that the bone scintiscan is more sensitive than conventional radiography in detecting focal disease of bone, and its ability to reflect the immediate status of bone further complements radiographic findings. The main limitation of this method relates to nonspecificity of the results obtained.

Bone Diseases↗
PubMed1975

Bone scanning.

Scanning is based on the uptake of a nuclide by the crystal lattice of bone and is related to bone blood flow. Cancer cells do not take up the tracer. Normally, the scan visualizes the highly vascular bones. Scans are useful and are indicated in metastatic bone disease, primary bone tumors, hematologic malignancies and some non-neoplastic diseases. The scan is more sensitive than x-ray in the detection of malignant diseases of the skeleton.

Adult↗
PubMed1999

Evidence of genocide 7000 BP--Neolithic paradigm and geo-climatic reality.

The early Neolithic fortified settlement of Schletz, Lower Austria is emerging as one of the most interesting sites of Linear Pottery culture excavation in Austria. In the course of systematic investigations carried out since 1983, a plethora of unexpected results have been obtained. Specifically, the human skeletal remains of 67 individuals have been found at the base of an oval trench system. Without exception, these remains are characterized by multiple traumatic lesions as well as carnivore gnaw marks. Demographic analysis presents the picture of the entire population of this early farming settlement having been extinguished. Further, the findings suggest that a genocide scenario may have been responsible for the final demise of this settlement. The age and sex distribution reveals a lack of young females, who are interpreted as having been abducted by aggressors. There is however no direct skeletal evidence of aggressors at the site; in fact, the uniformity of Strontium isotope ratios (HR-ICP-MS analysis) implies that all 67 individuals, who were left unburied for months, were indigenous. Supporting evidence of increased levels of inter-human aggression--possibly caused by a broad wave of migration--comes from other contemporary end linear pottery sites in Germany. Such findings are here discussed in the context of a dramatic geological event in the region of the Black Sea shelf at this time (7.550 BP), which led to the submergence of some 100.000 square kilometers of fertile land, and which might have been responsible for subsequent gradual population movements into the interior of Europe.

Animals↗
PubMed1975

The clinical role of skeletal scanning.

Malignant disease very often spreads to the skeleton. This is particularly true for carcinomas of the breast, the lungs, the prostate, and the thyroid. Knowledge of the state of the skeleton in these disorders is therefore desirable since patient management will largely depend on the early detection of bony deposits. Primary bone disease often spreads to soft tissue (lungs), and the early detection of this may alter significantly the therapeutic approach to the primary lesion. Traditionally, X-ray skeletal surveys and serum enzyme measurements provide indices which can be used in the staging of these disorders. Complementary techniques such as mammography, xeroradiography, thermography, and radionuclide imaging have been used to provide further relevant information. A number of benign bone diseases need early assessment in order to institute the best form of treatment. It is of importance to assess the circulation in localized areas of bone and to predict the appearance of avascular necrosis, to understand the healing mechanisms involved in fractures, and to predict the outcome of bone grafting. In this paper the clinical role of bone scanning is reviewed, particular attention being given to the recent advances brought about by the introduction of the 99mTc compounds. It is important that the non-specialist should be aware of the great improvement in the results obtained and in the help they can give him in deciding on the best management of each patient as an individual.

Bone Diseases↗
PubMed1977

[Skeletal scintigraphy in otolaryngology (author's transl)].

Close relation of non osseus facial skull portions to the skeleton cause rapidly the bone to become co-involved in presence of various diseases. Early diagnosis is of decisive importance for therapeutic measures. For localisation scintigraphy has proved particularly reliable in aids to early determination. This can be shown clearly in inflammatory diseases and tumour infiltrations with various tumour affections. Technical requirements and the use of skeletal scinitgraphy are demonstrated on hand of 6 cases.

Adult↗