Permeation through Phospholipid Bilayers,Skin‐Cell Penetration,Plasma Stability,and CD Spectra of α‐ and β‐Oligoproline Derivatives

After a survey of the special role, which the amino acid proline plays in the chemistry of life, the cell‐penetrating properties of polycationic proline‐containing peptides are discussed, and the widely unknown discovery by the Giralt group (J. Am. Chem. Soc. 2002 , 124, 8876) is acknowledged, according to which fluorescein‐labeled tetradecaproline is slowly taken up by rat kidney cells (NRK‐49F). Here, we describe details of our previously mentioned (Chem. Biodiversity 2004 , 1, 1111) observation that a hexa‐β³‐Pro derivative penetrates fibroblast cells, and we present the results of an extensive investigation of oligo‐L ‐ and oligo‐D ‐α‐prolines, as well as of oligo‐β²h‐ and oligo‐β³h‐prolines without and with fluorescence labels ( 1 – 8 ; Fig. 1). Permeation through protein‐free phospholipid bilayers is detected with the nanoFAST biochip technology (Figs. 2–4). This methodology is applied for the first time for quantitative determination of translocation rates of cell‐penetrating peptides (CPPs) across lipid bilayers. Cell penetration is observed with mouse (3T3) and human foreskin fibroblasts (HFF; Figs. 5 and 6–8, resp.). The stabilities of oligoprolines in heparin‐stabilized human plasma increase with decreasing chain lengths (Figs. 9–11). Time‐ and solvent‐dependent CD spectra of most of the oligoprolines (Figs. 13 and 14) show changes that may be interpreted as arising from aggregation, and broadening of the NMR signals with time confirms this assumption.     

Normal hematopoiesis and hematologic malignancies: Role of canonical Wnt signaling pathway and stromal microenvironment

Wnts are a family of evolutionary-conserved secreted signaling molecules critically involved in a variety of developmental processes and in cell fate determination. A growing body of evidence suggests that Wnt signaling plays a crucial role in the influence of bone marrow stromal microenvironment on the balance between hematopoietic stem cell self-renewal and differentiation. Emerging clinical and experimental evidence also indicates Wnt signaling involvement in the disruption of the latter balance in hematologic malignancies, where the stromal microenvironment favors the homing of cancer cells to the bone marrow, as well as leukemia stem cell development and chemoresistance. In the present review, we summarize and discuss the role of the canonical Wnt signaling pathway in normal hematopoiesis and hematologic malignancies, with regard to recent findings on the stromal microenvironment involvement in these process and diseases.     

Bcl-2 and Bcl-XL regulate proinflammatory caspase-1 activation by interaction with NALP1

Caspases are intracellular proteases that cleave substrates involved in apoptosis or inflammation. In C. elegans, a paradigm for caspase regulation exists in which caspase CED-3 is activated by nucleotide-binding protein CED-4, which is suppressed by Bcl-2-family protein CED-9. We have identified a mammalian analog of this caspase-regulatory system in the NLR-family protein NALP1, a nucleotide-dependent activator of cytokine-processing protease caspase-1, which responds to bacterial ligand muramyl-dipeptide (MDP). Antiapoptotic proteins Bcl-2 and Bcl-X(L) bind and suppress NALP1, reducing caspase-1 activation and interleukin-1beta (IL-1beta) production. When exposed to MDP, Bcl-2-deficient macrophages exhibit more caspase-1 processing and IL-1beta production, whereas Bcl-2-overexpressing macrophages demonstrate less caspase-1 processing and IL-1beta production. The findings reveal an interaction of host defense and apoptosis machinery.     

Conservative N cycling despite high atmospheric deposition in early successional African tropical lowland forests

Plant and Soil - Many applied disciplines have recognized problems related to the practice of data analysis within their own communities. Some of them have even declared the existence of a...     

The effect of highly active antiretroviral therapy on the survival of HIV-infected children in a resource-deprived setting: a cohort study

Background

The effect of highly active antiretroviral therapy (HAART) on the survival of HIV-infected children has not been well quantified. Because most pediatric HIV occurs in low- and middle-income countries, our objective was to provide a first estimate of this effect among children living in a resource-deprived setting.

Methods and Findings

Observational data from HAART-naïve children enrolled into an HIV care and treatment program in Kinshasa, Democratic Republic of the Congo, between December 2004 and May 2010 were analyzed. We used marginal structural models to estimate the effect of HAART on survival while accounting for time-dependent confounders affected by exposure. At the start of follow-up, the median age of the 790 children was 5.9 y, 528 (66.8%) had advanced or severe immunodeficiency, and 405 (51.3%) were in HIV clinical stage 3 or 4. The children were observed for a median of 31.2 mo and contributed a total of 2,089.8 person-years. Eighty children (10.1%) died, 619 (78.4%) initiated HAART, six (0.8%) transferred to a different care provider, and 76 (9.6%) were lost to follow-up. The mortality rate was 3.2 deaths per 100 person-years (95% confidence interval [CI] 2.4–4.2) during receipt of HAART and 6.0 deaths per 100 person-years (95% CI 4.1–8.6) during receipt of primary HIV care only. The mortality hazard ratio comparing HAART with no HAART from a marginal structural model was 0.25 (95% CI 0.06–0.95).

Conclusions

HAART reduced the hazard of mortality in HIV-infected children in Kinshasa by 75%, an estimate that is similar in magnitude but with lower precision than the reported effect of HAART on survival among children in the United States. Please see later in the article for the Editors'' Summary     

Cloning and characterization of differentially expressed genes of internal breakdown in mango fruit (Mangifera indica)

Internal breakdown in mango fruits has become a major concern in recent years. This disorder renders the fruits unfit for human consumption. The overall loss due to this disorder is about 35-55%. Environmental and physiological factors like high temperature, humidity, respiration and low transpiration rates have been attributed to cause spongy tissue due to reduced loss of heat from fruits. Biochemical studies have shown that there is a reduction in pH, total soluble solids, ascorbic acid, total sugars and carotenoids, low reducing and non-reducing sugar contents, lower amylase and invertase activities and high acid and starch content in spongy tissue affected pulp. There are no reports on molecular studies to determine changes in gene expression in these tissues. The present study was conducted using PCR based subtractive hybridization and RNA gel blot analysis of a few selected genes. The latter showed a higher expression of catalase, ubiquitin, alcohol dehydrogenase, coproporphyrinogen oxidase and keratin associated protein. A lower expression of ribosomal gene, fructose bisphosphate aldolase and cysthathionine gamma synthase was also noticed in spongy tissue. Biochemical studies indicated a lower amylase activity and a lower content of the total and reducing sugars in spongy tissue as compared to healthy tissue. Analyses of results indicate that oxidative stress may be one of the causes for formation of spongy tissue, which affects the expression of many genes. The role of these genes in spongy tissue formation is discussed.     

Interactions between bone marrow stromal microenvironment and B-chronic lymphocytic leukemia cells: Any role for Notch,Wnt and Hh signaling pathways?

B-cell chronic lymphocytic leukemia (CLL), which is the most common lymphoproliferative disorder, displays characteristics consistent with a defect in programmed cell death and exhibit prolonged survival of affected cells in vivo. When recovered from peripheral blood or lymphoid tissues of patients and cultured in vitro, CLL malignant cells rapidly undergo spontaneous apoptosis. CLL B-cells co-culture with different adherent cell types, collectively referred to as stromal cells, induces leukemia cell survival, migration, and drug resistance. In addition, such survival-promoting microenvironments can rescue leukemia cells from cytotoxic therapy, giving way to disease relapse. Quite surprisingly considering that many anti-cancer drugs, including γ-secretase inhibitors, Cyclopamine and Quercetin, were reported to block Notch, Wnt, and Hedgehog anti-apoptotic signaling pathways respectively, the link between the latter anti-apoptotic pathways and bone marrow stromal cells in CLL has been pointed out only recently. Data concerning the pathogenesis of CLL have been critically reviewed in regards to the growing body of evidence indicating deregulations of Notch, Wnt and Hedgehog anti-apoptotic signaling pathways in the stromal microenvironment of affected cells.     

Influence of mitochondrial DNA level on cellular energy metabolism: implications for mitochondrial diseases

The total amount of cellular mitochondrial DNA (mtDNA) varies widely and seems to be related to the nature and metabolic state of tissues and cells in culture. It is not known, however, whether this variation has any significance in vivo, and to which extent it regulates energy production. To better understand the importance of the cellular mtDNA level, we studied the influence of a gradual reduction of mtDNA copy number on oxidative phosphorylation in two models: (a) a control human cell line treated with different concentrations of 2′, 3′-dideoxycytidine, a nucleoside analogue that inhibits mtDNA replication by interfering with mitochondrial DNA polymerase γ, and (b) a cell line derived from a patient presenting mtDNA depletion. The two models were used to construct biochemical and phenotypic threshold curves. Our results show that oxidative phosphorylation activities are under a tight control by the amount of mtDNA in the cell, and that the full complement of mtDNA molecules are necessary to maintain a normal energy production level.