The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global ...scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
Abstract Objectives The aim of this study was to evaluate the bone tissue response to fiber-reinforced composite (FRC) in comparison with titanium (Ti) implants after 12 weeks of implantation in ...cancellous bone using histomorphometric and ultrastructural analysis. Materials and methods Thirty grit-blasted cylindrical FRC implants with BisGMA–TEGDMA polymer matrix were fabricated and divided into three groups: (1) 60 s light-cured FRC (FRC-L group), (2) 24 h polymerized FRC (FRC group), and (3) bioactive glass FRC (FRC–BAG group). Titanium implants were used as a control group. The surface analyses were performed with scanning electron microscopy and 3D SEM. The bone–implant contact (BIC) and bone area (BA) were determined using histomorphometry and SEM. Transmission electron microscopy (TEM) was performed on Focused Ion Beam prepared samples of the intact bone–implant interface. Results The FRC, FRC–BAG and Ti implants were integrated into host bone. In contrast, FRC-L implants had a consistent fibrous capsule around the circumference of the entire implant separating the implant from direct bone contact. The highest values of BIC were obtained with FRC–BAG (58 ± 11%) and Ti implants (54 ± 13%), followed by FRC implants (48 ± 10%), but no significant differences in BIC or BA were observed ( p = 0.07, p = 0.06, respectively). TEM images showed a direct contact between nanocrystalline hydroxyapatite of bone and both FRC and FRC–BAG surfaces. Conclusion Fiber-reinforced composite implants are capable of establishing a close bone contact comparable with the osseointegration of titanium implants having similar surface roughness.
Commercially-pure titanium (cp-Ti) and the titanium-aluminum-vanadium alloy (Ti6Al4V) are widely used as reconstructive implants for skeletal engineering applications, due to their good mechanical ...properties, biocompatibility and ability to integrate with the surrounding bone. Electron beam melting technology (EBM) allows the fabrication of customized implants with tailored mechanical properties and high potential in the clinical practice. In order to augment the interaction with the biological tissue, stem cells have recently been combined with metallic scaffolds for skeletal engineering applications. We previously demonstrated that human embryonic stem cell-derived mesodermal progenitors (hES-MPs) hold a great potential to provide a homogeneous and unlimited supply of cells for bone engineering applications. This study demonstrates the effect of EBM-fabricated cp-Ti and Ti6Al4V porous scaffolds on hES-MPs behavior, in terms of cell attachment, growth and osteogenic differentiation. Displaying different chemical composition but similar surface properties, EBM-fabricated cp-Ti and Ti6Al4V scaffolds supported cell attachment and growth, and did not seem to alter the expression of genes involved in osteogenic differentiation and affect the alkaline phosphatase activity. In conclusion, interfacing hES-MPs to EBM-fabricated scaffolds may represent an interesting strategy for design of third-generation biomaterials, with the potential to promote implant integration in clinical conditions characterized by poor bone quality.
Tumor Therapy with Targeted Atomic Nanogenerators McDevitt, Michael R.; Ma, Dangshe; Lai, Lawrence T. ...
Science (American Association for the Advancement of Science),
11/2001, Letnik:
294, Številka:
5546
Journal Article
Recenzirano
A single, high linear energy transfer alpha particle can kill a target cell. We have developed methods to target molecular-sized generators of alpha-emitting isotope cascades to the inside of cancer ...cells using actinium-225 coupled to internalizing monoclonal antibodies. In vitro, these constructs specifically killed leukemia, lymphoma, breast, ovarian, neuroblastoma, and prostate cancer cells at becquerel (picocurie) levels. Injection of single doses of the constructs at kilobecquerel (nanocurie) levels into mice bearing solid prostate carcinoma or disseminated human lymphoma induced tumor regression and prolonged survival, without toxicity, in a substantial fraction of animals. Nanogenerators targeting a wide variety of cancers may be possible.
The self-assembly of monolayers of benzyl mercaptan (benzenemethanethiol, C
6H
5CH
2SH) on Au(1
1
1) at room temperature has been studied by low energy electron diffraction and high resolution ...electron energy loss spectroscopy (EELS). It was found that the orientation of the molecule depends on coverage with the aromatic ring being parallel to the surface for low coverage and more perpendicular at higher coverage. Low energy electron diffraction indicates a (√7×√7)
R19.1° adsorbate structure at saturation coverage.
Pharmacogenomics: an in-house advantage? Borchardt, Paul E.
Drug discovery today,
January 2006, 2006-Jan, 2006-01-00, 20060101, Letnik:
11, Številka:
1-2
Journal Article
Recenzirano
The growing interest in pharmacogenomics and the recent solicitation of pharmacogenomic data by the FDA suggest that submissions of this data for the regulatory approval of new drugs might become ...mandatory in the future.
Most patients with ovarian cancer have disease in the peritoneal cavity. Treatment of this region is inadequate because recurrences are frequent. Increased radiation doses to tumor and, hence, ...greater tumor control may be possible with intraperitoneal (i.p.) administration of radiolabeled human monoclonal immunoglobulin M (IgM), which is reactive with tumor-associated antigens.
Biodistribution studies were performed in nude mice bearing i.p. nodules of human ovarian cancer after administration of human monoclonal IgMlambda (AC6C3-2B12), labeled with 111In or 90Y. Irrelevant 111In-labeled human IgMlambda (CH-1B9) and 90Y-aggregate served as specificity controls.
Intravenous administration of 111In-labeled AC6C3-2B12 produced low tumor and high liver and spleen uptake. Intraperitoneal administration of AC6C3-2B12 labeled with 111In or 90Y resulted in rapid, high tumor uptake (>45% of injected dose per gram of tumor at 3 hr) that was at least three-fold higher than any normal organ. Biodistribution results were similar for 111In- and 90Y-labeled IgM. Tumor uptake of 111In-labeled AC6C3-2B12 was two-fold greater than that of 111In-labeled CH-1B9. Normal organ uptakes were similar for tumor-reactive and irrelevant IgM. Radioimmunoconjugates were retained in the peritoneal cavity for a prolonged period of time. Yttrium-90 aggregate demonstrated high tumor and bone uptake.
Higher tumor uptake was observed after i.p. administration of tumor-reactive IgM than after irrelevant IgM. The in vivo behavior of tumor-reactive IgM was similar when it was radiolabeled with either 111In or 90Y. Therefore, 111In-based imaging studies can be used to predict the biodistribution of subsequently administered 90Y-labeled IgM. Further development of radiolabeled AC6C3-2B12 as a diagnostic and therapeutic agent for patients with advanced ovarian carcinoma is warranted.
An expression plasmid encoding the extracellular portion of the human tumor necrosis factor (TNF) type 1 receptor (TNF-R1) was constructed and used to generate a stable cell line secreting soluble ...TNF-R1 (sTNF-R1). The sTNF-R1 was purified, and its biochemical properties and its interactions with human TNF-alpha were examined. SDS-PAGE resolved the purified sTNF-R1 into three bands of approximate Mr 24,200, 28,200, and 32,800. Sedimentation equilibrium analysis gave a molecular weight of 25,000 for sTNF-R1 whereas the molecular weight obtained by gel filtration chromatography was approximately 55,000-60,000. Scatchard analysis of 125ITNF-alpha binding to sTNF-R1 revealed high-affinity binding (Kd = 93 pM), comparable to that observed for the intact receptor on whole cells. Competitive binding experiments showed that sTNF-R1 has a 50-60-fold higher affinity for TNF-alpha than for TNF-beta, in contrast to the equal affinities of TNF-alpha and TNF-beta for the full-length TNF-R1 transiently expressed in mammalian cells. The sTNF-R1 was found to block the cytotoxicity of TNF-alpha and TNF-beta on a murine L-M cell assay. The sizes of the sTNF-R1.TNF-alpha complex determined by gel filtration chromatography and sedimentation equilibrium were approximately 141 and 115 kDa, respectively. The stoichiometry of the complex was examined by Scatchard analysis, size-exclusion chromatography, HPLC separation, amino acid composition, sequence analysis, and sedimentation equilibrium. The data from these studies suggest that at least two molecules of sTNF-R1 can bind to a single TNF-alpha trimer.
In an effort to improve loco-regional control of ovarian cancer, intraperitoneal (i.p.) administration of an yttrium-90 (90Y) labeled human IgM was studied in a nude mouse model of the disease.
...Athymic nude mice bearing i.p. nodules of SKOV3 NMP2, a human ovarian carcinoma cell line, received single (50-400 microCi) or fractionated (150-510 microCi) administrations of 90Y-labeled 2B12. Untreated mice and mice treated with unlabeled immunoconjugate served as controls. Mice were monitored for weight loss, blood counts and survival.
Mice that received at least 300 microCi of 90Y-labeled 2B12 in a single administration lost more than 10% of their body weight with some early deaths, both of which were prevented with fractionated administration. Granulocytes and lymphocytes declined with treatment while red blood cell counts were relatively stable. Untreated mice and mice treated with unlabeled immunoconjugate had a median survival time of 20 and 17 days respectively. Treatment with 90Y-labeled 2B12 increased median survival by 11-12 days per 100 microCi for single (50-300 microCi) and fractionated administrations (150-510 microCi). The highest fractionated activity produced over three logs of tumor cell kill without significant toxicity.
Intraperitoneal RIT with 90Y-labeled 2B12 appears to be an attractive modality to treat peritoneal carcinomatosis and warrants further development.
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