theta-defensins prevent HIV-1 Env-mediated fusion by binding gp41 and blocking 6-helix bundle formation

Retrocyclin-1, a 0-defensin, protects target cells from human immunodeficiency virus, type 1 (HIV-1) by preventing viral entry. To delineate its mechanism, we conducted fusion assays between susceptible target cells and effector cells that expressed HIV-1 Env. Retrocyclin-1 (4 mu M) completely blocked fusion mediated by HIV-1 Envs that used CXCR4 or CCR5 but had little effect on cell fusion mediated by HIV-2 and simian immunodeficiency virus Envs. Retrocyclin-1 inhibited HIV-1 Env-mediated fusion without impairing the lateral mobility of CD4, and it inhibited the fusion of CD4-deficient cells with cells bearing CD4-independent HIV-1 Env. Thus, it could act without cross-linking membrane proteins or inhibiting gp120-CD4 interactions. Retrocyclin-1 acted late in the HIV-1 Env fusion cascade but prior to 6-helix bundle formation. Surface plasmon resonance experiments revealed that retrocyclin bound the ectodomain of gp41 with high affinity in a glycan-independent manner and that it bound selectively to the gp41 C-terminal heptad repeat. Native-PAGE, enzyme-linked immunosorbent assay, and CD spectroscopic analyses all revealed that retrocyclin-1 prevented 6-helix bundle formation. This mode of action, although novel for an innate effector molecule, resembles the mechanism of peptidic entry inhibitors based on portions of the gp41 sequence.

The effect of the CaO/SiO2 ratio on the phase equilibria in the ZnO-“Fe2O3”-(PbO + CaO + SiO2) system in air: CaO/SiO2 = 0.1, PbO/(CaO + SiO2) = 6.2, and CaO/SiO2 = 0.6, PbO/(CaO + SiO2) = 4.3

Experimental studies on phase equilibria in the multi-component system PbO-ZnO-CaO-SiO2-FeO-Fe2O3 in air have been conducted to characterize the phase relations of a complex slag system used in the oxidation smelting of lead and in typical lead blast furnace sinters. The liquidus in two pseudoternary sections ZnO-Fe2O3-(PbO + CaO + SiO2) with the CaO/SiO2 weight ratio of 0.1 and the PbO/(CaO + SiO2) weight ratio of 6.2, and with CaO/SiO2 weight ratio of 0.6 and the PbO/(CaO + SiO2) weight ratio of 4.3, have been constructed.

Synthesis of 1,3-diazepines and ring contraction to cyanopyrroles

Several tetrazolo[1,5-a] pyridines/2-azidopyridines undergo photochemical nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes (7,10,13,16,19,22) as well as ring cleavage to cyanovinylketenimines (8,17,20b) in low temperature Ar matrices. 6,8-Dichlorotetrazolo[1,5-a] pyridine/2-azido-3,5-dichloropridine 6 undergoes ready exchange of the chlorine in position 8 (3) with ROH/RONa. 8-Chloro-6-trifluoromethyltetrazolo[1,5-a] pyridine 15 undergoes solvolysis of the CF3 group to afford 8-chloro-6-methoxycarbonyltetrazolo[1,5-a] pyridine 18. Several tetrazolopyridines/2-azidopyridines afford 1H- or 5H-1,3-diazepines in good yields on photolysis in the presence of alcohols or amines (11,14,23,25). 5-Chlorotetrazolo[1,5-a] pyridines/2-azido-6-chloropyridines 21 and 38 undergo a rearrangement to 1H- and 3H-3-cyanopyrroles 27 and 45, respectively. The mechanism of this rearrangement was investigated by N-15-labelling and takes place via transient 1,3-diazepines. The structures of 6,8-dichloro-tetrazolo[1,5-a] pyridine 6T, 6-chloro-8-ethoxytetrazolo[1,5-a] pyridine 9Tb, dipyrrolylmethane 28, and 2-isopropoxy-4-dimethylamino-5H-1,3-diazepine 25b were determined by X-ray crystallography. In the latter case, this represents the first reported X-ray crystal structure of a 5H-1,3-diazepine.

Contribution of the collagen I alpha 1 and vitamin D receptor genes to the risk of hip fracture in elderly women

Context and Objective: Hip fracture is partially genetically determined. The present study was designed to examine the contributions of vitamin D receptor (VDR) and collagen I alpha 1 (COLIA1) genotypes to the liability to hip fracture in postmenopausal women. Design: The study was designed as a prospective population-based cohort investigation. Subjects: Six hundred seventy-seven postmenopausal women of Caucasian background, aged 70 +/- 7 yr (mean +/- SD), have been followed for up to 14 yr. Sixty-nine women had sustained a hip fracture during the period. Main Outcome: Atraumatic hip fractures were prospectively identified through radiologists' reports. Bone mineral density (BMD) at the hip and lumbar spine was measured by dual-energy x-ray absorptiometry. Genotypes: The TaqI and SpI COLIA1 polymorphisms of the VDR and COLIA1 genes were determined. Using the Single Nucleotide Polymorphism database, VDR TT, Tt, and tt genotypes were coded as TT, TC, and CC, whereas COLIA1 SS, Ss, and ss were coded as GG, GT, and TT. Results: Women with VDR CC genotype (16% prevalence) and COLIA1 TT genotype (5% prevalence) had an increased risk of hip fracture [odds ratio (OR) associated with CC, 2.6; 95% confidence interval (CI), 1.2-5.3; OR associated with TT, 3.8; 95% CI, 1.3-10.8] after adjustment for femoral neck BMD (OR, 3.4 per SD; 95% CI, 2.3-5.0) and age (OR, 1.4 per 5 yr; 95% CI, 1.1-1.7). Approximately 20 and 12% of the liability to hip fracture was attributable to the presence of the CC genotype and TT genotype, respectively. Conclusion: The VDR CC genotype and COLIA1 TT genotype were associated with increased hip fracture risk in Caucasian women, and this association was independent of BMD and age.

The Runx1 transcription factor controls CSF-1-dependent and -independent growth and survival of macrophages

Gene translocations that repress the function of the Runx1 transcription factor play a critical role in the development of myeloid leukemia. In this report, we demonstrate that Runx1 precisely regulates c-fms (CSF-1 receptor) gene expression. Runx1 controlled expression by binding to multiple sites within the mouse c-fms gene, allowing interaction between promoter and downstream enhancer elements. The runx1 and c-fms genes showed an identical pattern of expression in mature macrophages. Runx1 expression was repressed in CSF-1 stimulated, proliferating bone marrow-derived macrophages (BMM) and significantly increased in quiescent, CSF-1 starved cells. The RAW264.7 and Mono-Mac-6, macrophage-like cell lines expressed low levels of Runx1 and both showed growth arrest and cell death with ectopic expression of Runx1. The EM-3 cell line, which represents an early myeloid progenitor cell line, showed growth arrest with Runx1 expression in the absence of any detectable changes in cell differentiation. These findings suggest that Runx1 regulates growth and survival of myeloid cells and provide a novel insight into the role of Runx family gene translocations in leukemogenesis.