The vaccinia virus gene I2L encodes a membrane protein with an essential role in virion entry

The previously unstudied vaccinia virus gene I2L is conserved in all orthopoxviruses. We show here that the 8-kDa I2 protein is expressed at late times of infection, is tightly associated with membranes, and is encapsidated in mature virions. We have generated a recombinant virus in which I2 expression is dependent upon the inclusion of tetracycline in the culture medium. In the absence of I2, the biochemical events of the viral life cycle progress normally, and virion morphogenesis culminates in the production of mature virions. However, these virions show an ~400-fold reduction in specific infectivity due to an inability to enter target cells. Several proteins that have been previously identified as components of an essential entry/fusion complex are present at reduced levels in I2-deficient virions, although other membrane proteins, core proteins, and DNA are encapsidated at normal levels. A preliminary structure/function analysis of I2 has been performed using a transient complementation assay: the C-terminal hydrophobic domain is essential for protein stability, and several regions within the N-terminal hydrophilic domain are essential for biological competency. I2 is thus yet another component of the poxvirus virion that is essential for the complex process of entry into target cells.     

Prostaglandin E2 mediates IL-1beta-related fibroblast mitogenic effects in acute lung injury through differential utilization of prostanoid receptors

The fibroproliferative response to acute lung injury (ALI) results in severe, persistent respiratory dysfunction. We have reported that IL-1beta is elevated in pulmonary edema fluid in those with ALI and mediates an autocrine-acting, fibroblast mitogenic pathway. In this study, we examine the role of IL-1beta-mediated induction of cyclooxygenase-2 and PGE2, and evaluate the significance of individual E prostanoid (EP) receptors in mediating the fibroproliferative effects of IL-1beta in ALI. Blocking studies on human lung fibroblasts indicate that IL-1beta is the major cyclooxygenase-2 mRNA and PGE2-inducing factor in pulmonary edema fluid and accounts for the differential PGE2 induction noted in samples from ALI patients. Surprisingly, we found that PGE2 produced by IL-1beta-stimulated fibroblasts enhances fibroblast proliferation. Further studies revealed that the effect of fibroblast proliferation is biphasic, with the promitogenic effect of PGE2 noted at concentrations close to that detected in pulmonary edema fluid from ALI patients. The suppressive effects of PGE2 were mimicked by the EP2-selective receptor agonist, butaprost, by cAMP activation, and were lost in murine lung fibroblasts that lack EP2. Conversely, the promitogenic effects of mid-range concentrations of PGE2 were mimicked by the EP3-selective agent, sulprostone, by cAMP reduction, and lost upon inhibition of Gi-mediated signaling with pertussis toxin. Taken together, these data demonstrate that PGE2 can stimulate or inhibit fibroblast proliferation at clinically relevant concentrations, via preferential signaling through EP3 or EP2 receptors, respectively. Such mechanisms may drive the fibroproliferative response to ALI.     

DNA interstrand crosslinking agents: synthesis, DNA interactions, and cytotoxicity of dimeric achiral seco-amino-CBI and conjugates of achiral seco-amino-CBI with pyrrolobenzodiazepine (PBD)

The design and synthesis of three novel bisalkylating agents derived from the achiral seco-duocarmycin or CC-1065 analogs and pyrrolobenzodiazepines (PBDs) are described: achiral seco-CBI (cyclopropanebenz[e]indoline)-PBD 11, achiral seco-CI-PBD 12, and achiral seco-CBI dimer 13. Compounds 11 and 12 demonstrated enhanced cytotoxicity over the monomer counterparts against the growth of P815 murine mastocytoma cells in culture. Conjugate 11 was found to covalently react with adenine-N3 positions within the minor groove at AT-rich sequences and to produce DNA interstrand crosslinks. Both compounds were found to induce apoptosis in P815 cells. Due to its poor water solubility, dimer 13 did not give any appreciable DNA binding or cytotoxicity.     

Early nutritional stress impairs development of a song-control brain region in both male and female juvenile song sparrows (Melospiza melodia) at the onset of song learning

Birdsong is a sexually selected trait and is often viewed as an indicator of male quality. The developmental stress hypothesis proposes a model by which song could be an indicator; the time during early development, when birds learn complex songs and/or local variants of song, is of rapid development and nutritional stress. Birds that cope best with this stress may better learn to produce the most effective songs. The developmental stress hypothesis predicts that early food restriction should impair development of song-control brain regions at the onset of song learning. We examined the effect of food restriction on song-control brain regions in fledgling (both sexes, 23-26 days old) song sparrows (Melospiza melodia). Food restriction selectively reduced HVC volume in both sexes. In addition, sex differences were evident in all three song-control regions. This study lends further support to a growing body of literature documenting a variety of behavioural, physiological and neural detriments in several songbird species resulting from early developmental stress.     

Effect of clothing type on validity of air-displacement plethysmography

The purpose of the study was to evaluate the validity of an air-displacement plethysmography system (AP) within the general population, while wearing (1) a racing-type swimsuit (AP(SS)) and (2) participant's personal undergarments (AP(UG)), against hydrodensitometry (HW). Fifty women and 50 men were measured for body volume, density, and fat percentage by HW and compared with AP(SS) and AP(UG). For women, AP(UG) and AP(SS) were similar, although significant differences (p < 0.001) were observed between AP(UG) and HW and between AP(SS) and HW. For men, there was no significant difference between AP(UG) and HW; however, significant differences (P < or = 0.01) were found between AP(UG) and AP(SS) and between AP(SS) and HW. The small discrepancy in measured values between AP and HW are within the measurement error for the instrumentation and these data support the use of AP for determination of body composition in adults across a wide range of body size (body mass index [BMI] 17.7-35.2 kg.m(-2)) and age (18-57 y). Participants' personal undergarments provide a practical alternative to a spandex swimsuit when measuring body composition by AP in women but not in men.     

Murine models of pulmonary fibrosis

Human pulmonary fibrosis is characterized by alveolar epithelial cell injury, areas of type II cell hyperplasia, accumulation of fibroblasts and myofibroblasts, and the deposition of extracellular matrix proteins. The result is a progressive loss of normal lung architecture and impairment in gas exchange. Pertinent features of the human disease include temporal heterogeneity of the fibrotic lesions, progressive nature of the disease, development of fibrotic foci, and in some patients, a rapid worsening of symptoms known as an acute exacerbation. No current animal model recapitulates all of these cardinal manifestations of the human disease. However, investigations using murine models have led to the identification of many pathological cells and mediators that are believed to be important in human disease as well. In this review, we will summarize the characteristics, advantages, and disadvantages of many of the currently utilized murine models of pulmonary fibrosis.     

Exploration of the internal cavity of histone deacetylase (HDAC) with selective HDAC1/HDAC2 inhibitors (SHI-1:2)

We report herein the initial exploration of novel selective HDAC1/HDAC2 inhibitors (SHI-1:2). Optimized SHI-1:2 structures exhibit enhanced intrinsic activity against HDAC1 and HDAC2, and are greater than 100-fold selective versus other HDACs, including HDAC3. Based on the SAR of these agents and our current understanding of the HDAC active site, we postulate that the SHI-1:2 extend the existing HDAC inhibitor pharmacophore to include an internal binding domain.     

LC2, the Chlamydomonas Homologue of the t Complex-encoded Protein Tctex2, Is Essential for Outer Dynein Arm Assembly

Tctex2 is thought to be one of the distorter genes of the mouse t haplotype. This complex greatly biases the segregation of the chromosome that carries it such that in heterozygous +/t males, the t haplotype is transmitted to >95% of the offspring, a phenomenon known as transmission ratio distortion. The LC2 outer dynein arm light chain of Chlamydomonas reinhardtii is a homologue of the mouse protein Tctex2. We have identified Chlamydomonas insertional mutants with deletions in the gene encoding LC2 and demonstrate that the LC2 gene is the same as the ODA12 gene, the product of which had not been identified previously. Complete deletion of the LC2/ODA12 gene causes loss of all outer arms and a slow jerky swimming phenotype. Transformation of the deletion mutant with the cloned LC2/ODA12 gene restores the outer arms and rescues the motility phenotype. Therefore, LC2 is required for outer arm assembly. The fact that LC2 is an essential subunit of flagellar outer dynein arms allows us to propose a detailed mechanism whereby transmission ratio distortion is explained by the differential binding of mutant (t haplotype encoded) and wild-type dyneins to the axonemal microtubules of t-bearing or wild-type sperm, with resulting differences in their motility.