A Luminescent 1D Silver Polymer Containing [2.2]Paracyclophane Ligands.

[2.2]Paracyclophane scaffolds have seen limited use as building blocks in supramolecular chemistry. Here, we report the synthesis and characterization of a 1D coordination polymer consisting of silver(I) ions bound to a [2.2]paracyclophane scaffold functionalized with two 4-pyridyl units. The structure of the polymer has been determined from single crystal X-ray diffraction analysis and reveals two different silver coordination motifs that alternate along the 1D coordination polymer. The coordination polymer exhibits strong blue and sky-blue fluorescence in solution and in the crystalline solid state, respectively.

Wide-Bite-Angle Diphosphine Ligands in Thermally Activated Delayed Fluorescent Copper(I) Complexes: Impact on the Performance of Electroluminescence Applications.

We report a series of seven cationic heteroleptic copper(I) complexes of the form [Cu(P^P)(dmphen)]BF4, where dmphen is 2,9-dimethyl-1,10-phenanthroline and P^P is a diphosphine chelate, in which the effect of the bite angle of the diphosphine ligand on the photophysical properties of the complexes was studied. Several of the complexes exhibit moderately high photoluminescence quantum yields in the solid state, with ΦPL of up to 35%, and in solution, with ΦPL of up to 98%. We were able to correlate the powder photoluminescence quantum yields with the % Vbur of the P^P ligand. The most emissive complexes were used to fabricate both organic light-emitting diodes and light-emitting electrochemical cells (LECs), both of which showed moderate performance. Compared to the benchmark copper(I)-based LECs, [Cu(dnbp)(DPEPhos)]+ (maximum external quantum efficiency, EQEmax = 16%), complex 3 (EQEmax = 1.85%) showed a much longer device lifetime (t1/2 = 1.25 h and >16.5 h for [Cu(dnbp)(DPEPhos)]+ and complex 3, respectively). The electrochemiluminescence (ECL) properties of several complexes were also studied, which, to the best of our knowledge, constitutes the first ECL study for heteroleptic copper(I) complexes. Notably, complexes exhibiting more reversible electrochemistry were associated with higher annihilation ECL as well as better performance in a LEC.

High-Efficiency Deep-Blue-Emitting Organic Light-Emitting Diodes Based on Iridium(III) Carbene Complexes.

High-efficiency pure blue phosphorescent organic light-emitting diodes (OLEDs) remain one of the grand challenges, principally because the emissive complexes employed either do not possess sufficiently high photoluminescence quantum yields or exhibit unsatisfactory Commission International de l'Éclairage (CIE) coordinates. Here two deep-blue-emitting homoleptic iridium(III) complexes are reported and OLEDs are demonstrated with CIE coordinates of (0.15, 0.05) and maximum external quantum efficiency of 13.4%, which decreases slightly to 12.5% at 100 cd m-2 . They represent examples of the most efficient OLEDs surpassing the CIEy requirement of the National Television System Committee (NTSC) and the European Broadcasting Union (EBU). Emitter orientation contributes to the excellent device performance.

A population of very small embryonic-like (VSEL) CXCR4(+)SSEA-1(+)Oct-4+ stem cells identified in adult bone marrow.

By employing multiparameter sorting, we identified in murine bone marrow (BM) a homogenous population of rare (approximately 0.02% of BMMNC) Sca-1(+)lin(-)CD45- cells that express by RQ-PCR and immunohistochemistry markers of pluripotent stem cells (PSC) such as SSEA-1, Oct-4, Nanog and Rex-1. The direct electronmicroscopical analysis revealed that these cells are small (approximately 2-4 microm), posses large nuclei surrounded by a narrow rim of cytoplasm, and contain open-type chromatin (euchromatin) that is typical for embryonic stem cells. In vitro cultures these cells are able to differentiate into all three germ-layer lineages. The number of these cells is highest in BM from young (approximately 1-month-old) mice and decreases with age. It is also significantly diminished in short living DBA/2J mice as compared to long living B6 animals. These cells in vitro respond strongly to SDF-1, HGF/SF and LIF and express CXCR4, c-met and LIF-R, respectively, and since they adhere to fibroblasts they may be coisolated with BM adherent cells. We hypothesize that this population of Sca-1(+)lin(-)CD45- very small embryonic-like (VSEL) stem cells is deposited early during development in BM and could be a source of pluripotent stem cells for tissue/organ regeneration.

Right-sided aorta: a cadaver report and brief discussion of human aortic arch anomalies.

We observed an unusual right-sided aorta during routine laboratory dissection. The short aortic arch passed to the right side of the esophagus and trachea and had four branches, from proximal to distal: left common carotid, right common carotid, right subclavian, left subclavian arteries. The ligamentum arteriosum connected the pulmonary trunk to the left subclavian artery and lay to the left of the esophagus and trachea. The left recurrent laryngeal nerve passed under the ligamentum arteriosum while the right recurrent laryngeal nerve passed under the aortic arch. The descending thoracic aorta was situated near the midline, anterior to the vertebral bodies; consequently, the right posterior intercostal arteries were shorter than normal. The large veins of the thorax and the other thoracic organs appeared normal.

Analysis of pulmonary fat embolism in blunt force fatalities.

OBJECTIVE: To investigate the incidence, severity, and origin of pulmonary fat embolism (PFE) in persons dying from blunt force trauma within 24 hours of injury. METHODS: The study population consisted of blunt force fatalities. Controls were subjects dying from natural causes or nonblunt force injury. Tissue was removed from lung lobes and prepared for histologic examination using osmium tetroxide to stain for fat. Lung sections were graded for PFE on a scale of 0 (no emboli) to 4 (five or more emboli in a majority of fields). RESULTS: The blunt force group consisted of 56 decedents. Mortality was 93% within 4 hours. Fractures were present in 54 (96%) of decedents, and soft tissue injury was universal. Thirty eight (68%) of decedents were positive for PFE vs. 3 of 20 (15%) in controls. Mean score for PFE was 2.94 +/- 1.15 and 1.01 +/- 0.94, respectively (p < 0.005). Bone marrow emboli were not observed in any of the sections. Severity of PFE was positively associated with survival time. Analysis of PFE against sex, age, height, weight, number of injuries, and number of fractures showed no significant correlations. CONCLUSIONS: A significant degree of PFE develops rapidly in a majority of persons dying of blunt force trauma. Although the source of fat for embolization has been suggested to be bone marrow, no evidence of myeloid tissue was found in any of the lung sections. Nor was there a correlation of PFE and number of fractures. Soft tissue injury is considered the primary cause of PFE.

Changing the legacy of suicide.

In the United States, despite the increase in knowledge about suicide, the rate of suicide has remained virtually unchanged for the past 30 years. The members of the American Association of Suicidology (AAS) are uniquely qualified to determine what, if anything, can be done to reduce the rate of suicide. The restructuring of the association has produced the potential for cross-divisional collaboration, and yet conventional membership boundaries have resulted in unrealized opportunities to impact the rate of suicide. Dr. Edwin Shneidman, stated in Albert Cain's 1972 landmark book Survivors of Suicide that "postvention is prevention for the next generation" (p. x). The ability to design, implement, and study an effective model of postvention is within the considerable talents of our membership; however, doing so will require the commitment and flexibility of the entire association. By making postvention collaboration a goal of the association we can bring a national focus on suicide that could change the legacy of suicide.

Comparison of the effects of commonly used wound agents on epithelialization and neovascularization.

BACKGROUND: The primary effect sought with most topical wound therapy is antimicrobial. Topical wound agents are thought to promote normal healing by protecting the wound from infection. In this study, we examined the effect of six commonly used topical wound agents (bacitracin, sodium hypochlorite, silver nitrate, silver sulfadiazine, mafenide acetate, and povidone-iodine) on epithelialization and neovascularization in noninfected wounds. For this study, a new wound model was used in which direct visualization and quantification of wound epithelialization and neovascularization were carried out throughout the entire healing process. STUDY DESIGN: We measured the effect which 500 U per g of bacitracin, 0.25 percent of sodium hypochlorite, 0.5 percent silver nitrate, 1 percent silver sulfadiazine, 8.5 percent mafenide acetate, and 10 percent povodione-iodine had on the rate of wound epithelialization and neovascularization. The agents were applied topically to 99 circular full-thickness wounds (2.25 mm diameter, 0.125 mm depth) created on the dorsum of male hairless mouse ears. This model enabled us to visualize and measure directly wound epithelialization and neovascularization repeatedly throughout healing, using intravital video microscopy and computerized digitized planimetry. RESULTS: Control wounds and wounds treated with silver sulfadiazine (n = 18) and mafenide acetate (n = 14) epithelialized in 7.2 +/- 0.7, 7.1 +/- 0.3, and 7.3 +/- 0.3 days, respectively. This was significantly (p < 0.01) faster than the wounds treated with povidone-iodine (n = 10), sodium hypochlorite, (n = 8), and bacitracin (n = 13). Wounds treated with povidone-iodine epithelialized the slowest (11.8 +/- 0.55 days). Wound neovascularization was completed most rapidly in the groups treated with povidone-iodine and silver sulfadiazine (15.0 +/- 0.4 and 15.3 +/- 0.7 days, respectively). This was significantly (p < 0.05) faster than wounds treated with silver nitrate (n = 15), which neovascularized in 18.4 +/- 0.56 days. One-half of the wounds treated with sodium hypochlorite (eight of 16) did not epithelialize or neovascularize. CONCLUSIONS: The various antimicrobial agents studied in our in vivo model affect wound epithelialization and neovascularization differently. These effects on these two very important aspects of healing should be taken into consideration when indicating a specific agent for treatment of different types of wounds.

Immunochemical localization of extracellular materials in bone marrow of rats.

The distribution of type I collagen, fibronectin, laminin, and heparan sulfate was studied in marrow of rats by indirect immunofluorescence. Most of the type I collagen of marrow is associated with large blood vessels and connective tissue trabeculae, but type I collagen was also localized in a delicate meshwork throughout the marrow and in the basement membrane of the sinusoidal endothelium. Fibronectin is partially co-distributed with type I collagen, but is much more widely distributed. Sheets or septa of fibronectin-rich material divide the marrow into small compartments that contain and appear to separate clusters of developing blood cells. These septa may serve as a substrate for anchorage and migration of blood cells. Labeling of laminin was observed in the basement membranes of blood vessels, of fat cells, and of the sinusoidal wall, but only scattered labeling was seen in other extracellular materials. Heparan sulfate proteoglycan was poorly labeled in the extracellular matrix of marrow.

Ultrastructure of cytoskeletal elements of endothelial and stromal cells of rat marrow.

This study reports the distribution of microfilaments, microtubules, and intermediate filaments in endothelial cells, reticular cells, and macrophages of bone marrow of rats following fixation with glutaraldehyde, tannic acid, and saponin. In endothelial cells bundles of microfilaments are seen along the basal surface, where these cells adhere to underlying extracellular materials. The reticular cells, especially those that are closely associated with the endothelium of sinusoids, contain many intermediate filaments and microtubules as well as microfilaments. The reticular cell processes that partially cover the endothelium and extend among the blood cells have numerous microtubules and intermediate filaments arranged longitudinally within them; these cytoskeletal elements appear to provide mechanical support for the processes. Macrophages also have many microtubules and intermediate filaments but these organelles do not extend into the thin processes of these cells as is the case with reticular cells. Bundles of microfilaments are observed in the cytoplasm of adventitial and endothelial cells at sites where migrating blood cells are attached to these cells producing local regions of stress.

An electron microscopic study of microfibrils of bone marrow.

After fixation of bone marrow with glutaraldehyde, tannic acid and saponin, a delicate network of microfibrils (10 nm) was observed in the extracellular space. Masses of microfibrils were most frequently observed between the endothelial cells of the sinusoidal wall and adventitial reticular cells, but were also observed at other sites throughout the marrow stroma. Microfibrils are an important component of the extracellular material of bone marrow and appear to provide an anchoring substrate for the endothelium.

Ultrastructural studies of intercellular contacts (junctions) in bone marrow. A review.

This paper reviews ultrastructural studies of the intercellular contacts or junctions between cells of the bone marrow. Studies using tannic acid and glutaraldehyde as a fixative have shown pentalaminar complexes between many types of cells in marrow of mice and chicks. These intercellular contacts occur between adjacent stromal cells, between stromal cells and developing blood cells and, in marrow of mice, between migrating blood cells and cells of the sinusoidal wall. Because of their location and widespread occurrence, it is believed these contacts may represent a type of adherent junction helping to maintain an orderly arrangement of blood cells and stromal cells in the marrow. Migrating blood cells may use these contacts as anchoring sites during locomotion toward the sinusoids and in crossing the sinusoidal wall. On the other hand, since these junctions resemble gap junctions of other tissues, one should not exclude the possibility that they are involved in cellular communication. Freeze-fracture and lanthanum impregnation studies have failed to demonstrate these junctions in marrow. Studies using ruthenium red have shown apparent sites of attachment between cells of the marrow, but it is not known whether these sites correspond to the intercellular contacts seen in tannic acid preparations.

Ultrastructure of bone marrow of rats after severe hemodilution with starch or modified hemoglobin.

The ultrastructure of bone marrow of rats was studied 24 h after exchange-transfusion with solutions of starch or modified hemoglobin to a hematocrit of 10-15. Blood smears of the transfused rats had 17-20% reticulocytes as compared to 5-6% for sham operated controls. In the transfused rats marrow macrophages had numerous heterolysosomes apparently containing the starch or hemoglobin from the transfused solutions. Endothelial cells and reticular cells also possessed a few heterolysosomes thought to contain starch or hemoglobin. Reticular cells of the transfused rats contained numerous glycogen particles scattered throughout the cytoplasm or arranged in large masses. Synthesis of glycogen may indicate a metabolic change in reticular cells in response to tissue hypoxia induced by the exchange-transfusion procedure.

Effects of scald injury on hepatic PO2, blood flow, and ultrastructure in the rat.

Stagnant hypoxia has been suggested as a significant factor underlying acute liver disease following thermal injury. To examine this possibility in circumstances of moderate scald injury, rats were dipped (15% body surface area) in 90-95 degrees C water for 25 sec, fluid resuscitated, and studied at 1, 6, and 24 h. Hepatic PO2, obtained by multicathode surface measurement, was reduced significantly at 1 h (10.8 vs. 20.8 mm Hg in controls), although clearance times for low dose indocyanine green (ICG) suggested normal liver blood flow. The reduction of PO2 was transient; at 6 h levels were only slightly lower than in controls. At 24 h, however, liver PO2 was again reduced significantly, albeit less deeply (14.9 mm Hg). Increased clearance times for low and high dose ICG at 24 h suggested impairment of both blood flow and hepatocyte function. Hepatic ultrastructure showed foci of cells with anomalous and degenerate mitochondria, atypical of those associated with hypoxia. Sinusoids were often occluded by aggregates of vesicles of hepatocyte origin. It is not clear that acute restriction of oxygen availability during the first hour postburn was of sufficient intensity to cause the liver pathology evident at 24 h.

Intercellular contacts of lymphocytes during migration across high-endothelial venules of lymph nodes. An electron microscopic study.

The migration of lymphocytes across the wall of high-endothelial venules was studied by electron microscopic examination of murine lymph nodes fixed with glutaraldehyde and tannic acid. Regions of close membrane apposition, referred to in the present study as "intercellular contacts," were observed between migrating lymphocytes and endothelial cells of the vessel wall. At high magnification the intercellular contacts resolve into pentalaminar structures resembling gap junctions. However, the location of these contacts suggests that they are regions of membrane adherence utilized for locomotion of the lymphocytes across the endothelium. At present, it is unclear whether these intercellular contacts are communicating junctions or sites of membrane adherence.

Intercellular contacts between migrating blood cells and cells of the sinusoidal wall of bone marrow. An ultrastructural study using tannic acid.

The migration of blood cells across the sinusoidal wall of murine bone marrow was studied following fixation with tannic acid-glutaraldehyde. Electron microscopic examination showed regions of close membrane apposition (referred to in this study as "intercellular contacts") between migrating blood cells and cells of the sinusoidal wall (adventitial and endothelial cells). Ultrastructurally the intercellular contacts are pentalaminar structures resembling gap junctions of other organs after tannic-acid fixation. The possibility that these contacts are regions of intercellular communication and/or sites of membrane attachment utilized for locomotion of the migrating blood cells is discussed.

Gap junctions between cells of bone marrow: an ultrastructural study using tannic acid.

In bone marrow of the mouse perfused with fixative containing tannic acid and glutaraldehyde, gap junctions were observed between certain cell types. Gap junctions were seen between adjacent reticular cells, between adjacent macrophages, and between macrophages and reticular cells. Macrophages formed gap junctions with immature neutrophils, eosinophils, monocytes, and erythroblasts. Often a single macrophage had gap junctions with neutrophilic, eosinophilic, and monocytic cells; these blood cells varied from immature to nearly mature forms. In contrast, the macrophages associated with erythroblasts had gap junctions only with erythroblasts and all the erythroblasts were in the same developmental stage. The possible role of the gap junctions in differentiation and mobilization of marrow cells is discussed.

Ultrastructural study of liver sinusoids of mice during invasion by leukemic myelocytes.

Results of an ultrastructural study of liver of RF mice during invasion by leukemic myelocytes were reported. In early stages of infiltration, leukemia cells adhered to the endothelial cells of the sinusoidal wall; gaps 1-4 mu in diameter then developed in the endothelium, and leukemia cells passed through the gaps to enter the extravascular space. Other sinusoids became occluded by leukemic myelocytes, the endotheilium disintegrated, and the occluding cells thus became extravascular. In late stages of infiltration, when leukemia cells migrated back into the sinusoids, the endothelium was continuous and leukemia cells passed through temporary pores located within endothelial cells.