X-ray Structure and Properties of the Ferrous Octaethylporphyrin Nitroxyl Complex

The preparation and characterization of the iron octaethylporphyrin nitroxyl ion, [Fe(OEP)(NO)−], is reported. The complex was synthesized by the one-electron reduction of Fe(OEP)(NO) using anthracenide as the reducing agent. The compound was isolated as the potassium (2.2.2)cryptand salt. The anion was characterized using X-ray analysis with visible and infrared spectroscopy. The spectral features of the iron nitroxyl complex were consistent with previous literature reports. The important structural changes upon reduction were a significant decrease in the Fe–N–O bond angle from 142° to 127° and an increase in the N–O bond length from that in the starting nitrosyl moiety. The porphyrin ring became significantly less planar upon reduction, but the displacement of the iron atom from the 24-atom plane was essentially unchanged. In spite of the attempt to encapsulate the potassium ion with the (2.2.2)cryptand, significant interaction between K+ and the oxygen of the nitroxyl were observed, indicating a contact ion pair in the crystal structure. Comparison between the experimental structure and the DFT-calculated parameters were reported. The results are consistent with the Fe–N–O moiety being the site of the reduction, with little evidence for the reduction of the iron itself or the porphyrin ring. The proton NMR spectrum was also obtained, and the chemical shifts were significantly different from other S = 0 metalloporphyrin complexes. These shifts, though, were consistent with the DFT calculations

Carbon−Phosphorus Bond Activation of Tri(2-thienyl)phosphine at Dirhenium and Dimanganese Centers

Reaction of [Re2(CO)9(NCMe)] with tri(2-thienyl)phosphine (PTh3) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re2(CO)9(PTh3)] (1), [Re2(CO)8(NCMe)(PTh3)] (2), and [Re2(CO)8(PTh3)2] (3). Complex 2 was also obtained from the room-temperature reaction of [Re2(CO)8(NCMe)2] with PTh3 and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene affords [Re2(CO)8(μ-PTh2)(μ-η1:κ1-C4H3S)] (4) and [Re2(CO)7(PTh3)(μ-PTh2)(μ-H)] (5), respectively, both resulting from carbon−phosphorus bond cleavage of a coordinated PTh3 ligand. Reaction of [Re2(CO)10] and PTh3 in refluxing xylene gives a complex mixture of products. These products include 3−5, two further binuclear products, [Re2(CO)7(PTh3)(μ-PTh2)(μ-η1:κ1-C4H3S)] (6) and [Re2(CO)7(μ-κ1:κ2-Th2PC4H2SPTh)(μ-η1:κ1-C4H3S)] (7), and the mononuclear hydrides [ReH(CO)4(PTh3)] (8) and trans-[ReH(CO)3(PTh3)2] (9). Binuclear 6 is structurally similar to 4 and can be obtained from reaction of the latter with 1 equiv of PTh3. Formation of 7 involves a series of rearrangements resulting in the formation of a unique new diphosphine ligand, Th2PC4H2SPTh. Reaction of [Mn2(CO)10] with PTh3 in refluxing toluene affords the phosphine-substituted product [Mn2(CO)9(PTh3)] (10) and two carbon−phosphorus bond cleavage products, [Mn2(CO)6(μ-PTh2)(μ-η1:η5-C4H3S)] (11) and [Mn2(CO)5(PTh3)(μ-PTh2)(μ-η1:η5-C4H3S)] (12). Both 11 and 12 contain a bridging thienyl ligand that is bonded to one manganese atom in a η5-fashion. The molecular structures of eight of these new complexes were established by single-crystal X-ray diffraction studies, allowing a detailed analysis of the disposition of the coordinated ligands

Mixed-metal Cluster Synthesis: [Re(CO)\u3csub\u3e3\u3c/sub\u3e(μ-S\u3csub\u3e2\u3c/sub\u3eNC\u3csub\u3e7\u3c/sub\u3eH\u3csub\u3e4\u3c/sub\u3e)]\u3csub\u3e2\u3c/sub\u3e as a Precursor for tri- and tetranuclear 2-mercaptobenzothiolato Capped Clusters

The readily prepared [Re2(CO)6(μ-S2NC7H4)2] (1) reacts with Group 8 trimetallic carbonyl clusters to yield new mixed-metal tri- and tetranuclear clusters. With [Os3(CO)10(NCMe)2] at 80 °C the tetranuclear mixed-metal cluster [Os3Re(CO)13(μ3-C7H4NS2)] (2) is the only isolated product. With Ru3(CO)12 products are dependent upon the reaction temperature. At 80 °C, a mixture of tetranuclear mixed-metal [Ru3Re(CO)13(μ3-C7H4NS2)] (5) and the triruthenium complex [Ru3(CO)9(μ-H)(μ3-C7H4NS2)] (4) results, while at 110 °C a second tetranuclear mixed-metal cluster, [Re2Ru2(CO)12(μ4-S)(μ-C7H4NS)(μ-C7H4NS2)] (3), resulting from carbon–sulfur bond scission, is the major product. Reaction of 1 With Fe3(CO)12 at 80 °C furnishes the trinuclear mixed-metal cluster [Fe2Re(CO)8(μ-CO)2(μ3-C7H4NS2)] (6). The reactivity of 6 has been probed with the aim of identifying any metal-based selectivity for carbonyl substitution. Addition of PPh3 in presence of Me3NO at 25 °C gives both the mono- and bis(phosphine)-substituted derivatives [Os3Re(CO)12(PPh3)(μ3-C7H4NS2)] (7) and [Os3Re(CO)11(PPh3)2(μ3-C7H4NS2)] (8). In 7 the PPh3 ligand occupies an axial site on wingtip osmium, while in 8 one PPh3 ligand is equatorially coordinated to wingtip osmium and the other is bonded to a hinge osmium. New complexes have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction studies

X-ray Structure of \u3cem\u3emer\u3c/em\u3e-[Mo(CO)\u3csub\u3e3\u3c/sub\u3e(PPh\u3csub\u3e3\u3c/sub\u3e)(\u3cem\u3eκ\u3c/em\u3e\u3csup\u3e2\u3c/sup\u3e-dppm)]

Treatment of [Mo(CO)3(NCMe)3] with bis(diphenylphosphino)methane (dppm) and triphenylphosphine (PPh3) at 50 °C afforded mer-[Mo(CO)3(PPh3)(κ2-dppm)] (1) in 55% yield which has been characterized by single crystal X-ray diffraction studies and spectroscopic measurements. Compound 1 crystallizes in the triclinic space group P−1 with a = 10.3449(6), b = 11.1570(6), c = 17.8961(10) Å, β = 80.8400(10)°, Z = 2 and V = 1959.8(2) Å3

Association of Variants at UMOD with Chronic Kidney Disease and Kidney Stones—Role of Age and Comorbid Diseases

Chronic kidney disease (CKD) is a worldwide public health problem that is associated with substantial morbidity and mortality. To search for sequence variants that associate with CKD, we conducted a genome-wide association study (GWAS) that included a total of 3,203 Icelandic cases and 38,782 controls. We observed an association between CKD and a variant with 80% population frequency, rs4293393-T, positioned next to the UMOD gene (GeneID: 7369) on chromosome 16p12 (OR = 1.25, P = 4.1×10−10). This gene encodes uromodulin (Tamm-Horsfall protein), the most abundant protein in mammalian urine. The variant also associates significantly with serum creatinine concentration (SCr) in Icelandic subjects (N = 24,635, P = 1.3×10−23) but not in a smaller set of healthy Dutch controls (N = 1,819, P = 0.39). Our findings validate the association between the UMOD variant and both CKD and SCr recently discovered in a large GWAS. In the Icelandic dataset, we demonstrate that the effect on SCr increases substantially with both age (P = 3.0×10−17) and number of comorbid diseases (P = 0.008). The association with CKD is also stronger in the older age groups. These results suggest that the UMOD variant may influence the adaptation of the kidney to age-related risk factors of kidney disease such as hypertension and diabetes. The variant also associates with serum urea (P = 1.0×10−6), uric acid (P = 0.0064), and suggestively with gout. In contrast to CKD, the UMOD variant confers protection against kidney stones when studied in 3,617 Icelandic and Dutch kidney stone cases and 43,201 controls (OR = 0.88, P = 5.7×10−5)

Population genetics of cancer cell clones: possible implications of cancer stem cells

Abstract Background The population dynamics of the various clones of cancer cells existing within a tumour is complex and still poorly understood. Cancer cell clones can be conceptualized as sympatric asexual species, and as such, the application of theoretical population genetics as it pertains to asexual species may provide additional insights. Results The number of generations of tumour cells within a cancer has been estimated at a minimum of 40, but high cancer cell mortality rates suggest that the number of cell generations may actually be in the hundreds. Such a large number of generations would easily allow natural selection to drive clonal evolution assuming that selective advantages of individual clones are within the range reported for free-living animal species. Tumour cell clonal evolution could also be driven by variation in the intrinsic rates of increase of different clones or by genetic drift. In every scenario examined, the presence of cancer stem cells would require lower selection pressure or less variation in intrinsic rates of increase. Conclusions The presence of cancer stem cells may result in more rapid clonal evolution. Specific predictions from theoretical population genetics may lead to a greater understanding of this process.</p

The Max b-HLH-LZ Can Transduce into Cells and Inhibit c-Myc Transcriptional Activities

The inhibition of the functions of c-Myc (endogenous and oncogenic) was recently shown to provide a spectacular therapeutic index in cancer mouse models, with complete tumor regression and minimal side-effects in normal tissues. This was achieved by the systemic and conditional expression of omomyc, the cDNA of a designed mutant of the b-HLH-LZ of c-Myc named Omomyc. The overall mode of action of Omomyc consists in the sequestration of Max and the concomitant competition of the Omomyc/Max complex with the endogenous c-Myc/Max heterodimer. This leads to the inhibition of the transactivation of Myc target genes involved in proliferation and metabolism. While this body of work has provided extraordinary insights to guide the future development of new cancer therapies that target c-Myc, Omomyc itself is not a therapeutic agent. In this context, we sought to exploit the use of a b-HLH-LZ to inhibit c-Myc in a cancer cell line in a more direct fashion. We demonstrate that the b-HLH-LZ domain of Max (Max*) behaves as a bona fide protein transduction domain (PTD) that can efficiently transduce across cellular membrane via through endocytosis and translocate to the nucleus. In addition, we show that the treatment of HeLa cells with Max* leads to a reduction of metabolism and proliferation rate. Accordingly, we observe a decrease of the population of HeLa cells in S phase, an accumulation in G1/G0 and the induction of apoptosis. In agreement with these phenotypic changes, we show by q-RT-PCR that the treatment of HeLa cells with Max* leads to the activation of the transcription c-Myc repressed genes as well as the repression of the expression of c-Myc activated genes. In addition to the novel discovery that the Max b-HLH-LZ is a PTD, our findings open up new avenues and strategies for the direct inhibition of c-Myc with b-HLH-LZ analogs

Inflammation Aggravates Disease Severity in Marfan Syndrome Patients

BACKGROUND: Marfan syndrome (MFS) is a pleiotropic genetic disorder with major features in cardiovascular, ocular and skeletal systems, associated with large clinical variability. Numerous studies reveal an involvement of TGF-beta signaling. However, the contribution of tissue inflammation is not addressed so far. METHODOLOGY/PRINCIPAL FINDINGS: Here we showed that both TGF-beta and inflammation are up-regulated in patients with MFS. We analyzed transcriptome-wide gene expression in 55 MFS patients using Affymetrix Human Exon 1.0 ST Array and levels of TGF-beta and various cytokines in their plasma. Within our MFS population, increased plasma levels of TGF-beta were found especially in MFS patients with aortic root dilatation (124 pg/ml), when compared to MFS patients with normal aorta (10 pg/ml; p = 8x10(-6), 95% CI: 70-159 pg/ml). Interestingly, our microarray data show that increased expression of inflammatory genes was associated with major clinical features within the MFS patients group; namely severity of the aortic root dilatation (HLA-DRB1 and HLA-DRB5 genes; r = 0.56 for both; False Discovery Rate(FDR) = 0%), ocular lens dislocation (RAET1L, CCL19 and HLA-DQB2; Fold Change (FC) = 1.8; 1.4; 1.5, FDR = 0%) and specific skeletal features (HLA-DRB1, HLA-DRB5, GZMK; FC = 8.8, 7.1, 1.3; FDR = 0%). Patients with progressive aortic disease had higher levels of Macrophage Colony Stimulating Factor (M-CSF) in blood. When comparing MFS aortic root vessel wall with non-MFS aortic root, increased numbers of CD4+ T-cells were found in the media (p = 0.02) and increased number of CD8+ T-cells (p = 0.003) in the adventitia of the MFS patients. CONCLUSION/SIGNIFICANCE: In conclusion, our results imply a modifying role of inflammation in MFS. Inflammation might be a novel therapeutic target in these patients

Pregnancy in the mature adult mouse does not alter the proportion of mammary epithelial stem/progenitor cells

Introduction In humans, an early full-term pregnancy reduces lifetime breast cancer risk by up to 50% whereas a later pregnancy (>35 years old) can increase lifetime risk. Several mechanisms have been suggested, including changes in levels of circulating hormones, changes in the way the breast responds to these hormones, changes in gene expression programmes which may alter susceptibility to transformation and changes to mammary stem cell numbers or behaviour. Previous studies have shown that the mammary tissue isolated from both virgin and parous mice has the ability to repopulate a cleared mammary fat pad in transplant experiments. Limited dilution transplant assays have demonstrated that early pregnancy (at 5 weeks of age) reduces stem/progenitor cell numbers in the mouse mammary epithelium by twofold. However, the effects on stem/progenitor cell numbers in the mammary epithelium of a pregnancy in older animals have not yet been tested. Methods Mice were put through a full-term pregnancy at 9 weeks of age, when the mammary epithelium is mature. The total mammary epithelium was purified from parous 7-week post-lactation and age-matched virgin mice and analysed by flow cytometry and limiting dilution cleared fat pad transplants. Results There were no significant differences in the proportions of different mammary epithelial cell populations or numbers of CD24+/Low Sca-1- CD49fHigh cells (stem cell enriched basal mammary epithelial compartment). There was no significant difference in stem/progenitor cell frequency based on limiting dilution transplants between the parous and age-matched virgin epithelium. Conclusions Although differences between parous and virgin mammary epithelium at later time points post lactation or following multiple pregnancies cannot be ruled out, there are no differences in stem/progenitor cell numbers between mammary epithelium isolated from parous animals which were mated at 9 weeks old and virgin animals. However, a recent report has suggested that animals that were mated at 5 weeks old have a twofold reduction in stem/progenitor cell numbers. This is of interest given the association between early, but not late, pregnancy and breast cancer risk reduction in humans. However, a mechanistic connection between stem cell numbers and breast cancer risk remains to be established

Spatial Analyses of Benthic Habitats to Define Coral Reef Ecosystem Regions and Potential Biogeographic Boundaries along a Latitudinal Gradient

Marine organism diversity typically attenuates latitudinally from tropical to colder climate regimes. Since the distribution of many marine species relates to certain habitats and depth regimes, mapping data provide valuable information in the absence of detailed ecological data that can be used to identify and spatially quantify smaller scale (10 s km) coral reef ecosystem regions and potential physical biogeographic barriers. This study focused on the southeast Florida coast due to a recognized, but understudied, tropical to subtropical biogeographic gradient. GIS spatial analyses were conducted on recent, accurate, shallow-water (0–30 m) benthic habitat maps to identify and quantify specific regions along the coast that were statistically distinct in the number and amount of major benthic habitat types. Habitat type and width were measured for 209 evenly-spaced cross-shelf transects. Evaluation of groupings from a cluster analysis at 75% similarity yielded five distinct regions. The number of benthic habitats and their area, width, distance from shore, distance from each other, and LIDAR depths were calculated in GIS and examined to determine regional statistical differences. The number of benthic habitats decreased with increasing latitude from 9 in the south to 4 in the north and many of the habitat metrics statistically differed between regions. Three potential biogeographic barriers were found at the Boca, Hillsboro, and Biscayne boundaries, where specific shallow-water habitats were absent further north; Middle Reef, Inner Reef, and oceanic seagrass beds respectively. The Bahamas Fault Zone boundary was also noted where changes in coastal morphologies occurred that could relate to subtle ecological changes. The analyses defined regions on a smaller scale more appropriate to regional management decisions, hence strengthening marine conservation planning with an objective, scientific foundation for decision making. They provide a framework for similar regional analyses elsewhere