Synthesis and evaluation of strand and turn modified ring-extended gramicidin S derivatives

In this paper, we describe the crystal structure of previously reported ring-extended gramicidin S (GS) derivative 2 (GS14K4), containing a d-amino acid residue in one of the β-strand regions. This structure is in agreement with a previously reported modeling study of the same molecule. The polar side chain of the additional d-amino acid residue is positioned at the same face of the molecule as the hydrophobic side chains, and we believe that because of this compound 2 is considerably less hydrophobic than extended GS derivatives in which the strand regions are exclusively composed of l-amino acids. Using this backbone structure as our benchmark we prepared a small series of ring-extended GS analogues featuring sugar amino acid dipeptide isosteres of varied hydrophobicity at the turn region. We show that via this approach hydrophobicity of extended GS analogues can be tuned without affecting the secondary structure (as observed from NMR and CD spectra). Biological evaluation reveals that hydrophobicity correlates to cell toxicity, but still bacteriolysis is induced with GS analogues that are too hydrophilic to efficiently lyse human red blood cells.     

Ethnicity and thrombolysis in ischemic stroke: a hospital based study in Amsterdam

Background  

Ethnic differences have been reported with regard to several medical therapies. The aim of this study was to investigate the relation between ethnicity and thrombolysis in stroke patients.     

Transgenic mice for cre-inducible overexpression of the Cul4A gene

The Cullin 4A(Cul4A) gene is important in cell survival, development, growth, and cell cycle control and is amplified in breast and hepatocellular cancers. Recently, we reported that Cul4A plays an oncogenic role in the pathogenesis of mesothelioma. An important strategy for studying Cul4A in different tissues is targeted overexpression of this gene in vivo. Studies of Cul4A in mice have been restricted to the loss-of-function studies using Cul4A knockout mice; gain-of-function studies of Cul4A using transgenic mice have not been reported. We, therefore, generated a gain-of-function transgenic mouse model that overexpresses Cul4A in a Cre-dependent manner. Before Cre recombination, these mice express LacZ during development in most adult tissues. After Cre-mediated excision of the LacZ reporter, the transfected Cul4A gene is expressed along with a C-terminal Myc-tag in different tissues. In this study, Cre-excision was induced in mouse lungs by inhalation of an adenovirus vector encoding Cre recombinase. This mouse model provides a valuable resource for investigating the significance of Cul4A overexpression in various tissues.     

The key to enabling biosurveillance is cooperative technology development

The world population will continue to face biological threats, whether they are naturally occurring or intentional events. The speed with which diseases can emerge and spread presents serious challenges, because the impact on public health, the economy, and development can be huge. The U.S. government recognizes that global public health can also have an impact on national security. This global perspective manifests itself in U.S. policy documents that clearly articulate the importance of biosurveillance in providing early warning, detection, and situational awareness of infectious disease threats in order to mount a rapid response and save lives. In this commentary, we suggest that early recognition of infectious disease threats, whether naturally occurring or man-made, requires a globally distributed array of interoperable hardware and software fielded in sufficient numbers to create a network of linked collection nodes. We argue that achievement of this end state will require a degree of cooperation that does not exist at this time-either across the U.S. federal government or among our global partners. Successful fielding of a family of interoperable technologies will require interagency research, development, and purchase ("acquisition") of biosurveillance systems through cooperative ventures that likely will involve our strategic allies and public-private partnerships. To this end, we propose leveraging an existing federal interagency group to integrate the acquisition of technologies to enable global biosurveillance.     

Solid�CLiquid Transitions and Stability of HPKO-in-Water Systems Emulsified by Dairy Proteins

Stability of oil-in-water emulsions during freezing and thawing is regulated by the phase transitions occurring in the continuous and dispersed phases upon thermal treatments and by the composition of the interfacial membrane. In the present study, the impact of the water phase formulation (0–2.5–5–10–20–30–40% w/w sucrose), the interfacial composition [whey protein isolates (WPI) or sodium caseinate (NaCas) used at different concentrations], and the particle size on the stability of hydrogenated palm kernel oil (30% w/w)-in-water systems was investigated. Phase/state behaviour of the continuous and dispersed phases and emulsion destabilisation were studied by differential scanning calorimetry. System morphology was observed by particle size analysis and optical microscopy. The presence of sucrose in the aqueous phase and reduced particle size distribution significantly improved emulsion stability. WPI showed better stabilising properties than NaCas at lipid to protein ratios of 10:1, 7.5:1, 5:1 and 4:1. Increased WPI concentration significantly improved emulsion resistance to breakdown during freeze–thaw cycling. NaCas showed poor stabilising properties and was ineffective in reducing emulsion destabilisation at 0% sucrose at all the lipid to protein ratios.     

Eavesdropping on plant volatiles by a specialist moth: significance of ratio and concentration

We investigated the role that the ratio and concentration of ubiquitous plant volatiles play in providing host specificity for the diet specialist grape berry moth Paralobesia viteana (Clemens) in the process of locating its primary host plant Vitis sp. In the first flight tunnel experiment, using a previously identified attractive blend with seven common but essential components ("optimized blend"), we found that doubling the amount of six compounds singly [(E)- & (Z)-linalool oxides, nonanal, decanal, β-caryophyllene, or germacrene-D], while keeping the concentration of other compounds constant, significantly reduced female attraction (average 76% full and 59% partial upwind flight reduction) to the synthetic blends. However, doubling (E)-4,8-dimethyl 1,3,7-nonatriene had no effect on female response. In the second experiment, we manipulated the volatile profile more naturally by exposing clonal grapevines to Japanese beetle feeding. In the flight tunnel, foliar damage significantly reduced female landing on grape shoots by 72% and full upwind flight by 24%. The reduction was associated with two changes: (1) more than a two-fold increase in total amount of the seven essential volatile compounds, and (2) changes in their relative ratios. Compared to the optimized blend, synthetic blends mimicking the volatile ratio emitted by damaged grapevines resulted in an average of 87% and 32% reduction in full and partial upwind orientation, respectively, and the level of reduction was similar at both high and low doses. Taken together, these results demonstrate that the specificity of a ubiquitous volatile blend is determined, in part, by the ratio of key volatile compounds for this diet specialist. However, P. viteana was also able to accommodate significant variation in the ratio of some compounds as well as the concentration of the overall mixture. Such plasticity may be critical for phytophagous insects to successfully eavesdrop on variable host plant volatile signals.     

α-Synuclein expression selectively affects tumorigenesis in mice modeling Parkinson's disease

Alpha Synuclein (α-Syn) is a protein implicated in mechanisms of neuronal degeneration in Parkinson's disease (PD). α-Syn is primarily a neuronal protein, however, its expression is found in various tumors including ovarian, colorectal and melanoma tumors. It has been hypothesized that neurodegeneration may share common mechanisms with oncogenesis. We tested whether α-Syn expression affects tumorigenesis of three types of tumors. Specifically, B16 melanoma, E0771 mammary gland adenocarcinoma and D122 Lewis lung carcinoma. For this aim, we utilized transgenic mice expression the human A53T α-Syn form. We found that the in vivo growth of B16 and E0771 but not D122 was enhanced in the A53T α-Syn mice. The effect on tumorigenesis was not detected in age-matched APP/PS1 mice, modeling Alzheimer's disease (AD), suggesting a specific effect for α-Syn-dependent neurodegeneration. Importantly, transgenic α-Syn expression was detected within the three tumor types. We further show uptake of exogenously added, purified α-Syn, by the cultured tumor cells. In accord, with the affected tumorigenesis in the young A53T α-Syn mice, over-expression of α-Syn in cultured B16 and E0771 cells enhanced proliferation, however, had no effect on the proliferation of D122 cells. Based on these results, we suggest that certain forms of α-Syn may selectively accelerate cellular mechanisms leading to cancer.     

An analysis of genetic variation across the MBL2 locus in Dutch Caucasians indicates that 3′ haplotypes could modify circulating levels of mannose-binding lectin

Mannose-binding protein (MBL) is a critical component of innate immunity and provides first-line protection against pathogens. Both circulating MBL serum levels and functional activity have been correlated with common genetic variants in the MBL2 gene. Associations between MBL deficiency and severe infections have been reported in immuno-incompetent patients and for autoimmune disorders; however, measured MBL serum levels do not fully correlate with the ‘secretor haplotypes’. Previously, the MBL2 locus was resequenced and determined that a recombination hotspot divides MBL2 into two haplotype blocks. It was sought to investigate whether additional variants, in either block structure could associate with MBL serum levels. Therefore, 31 common variants were analysed across the locus in 212 DNA samples of healthy Caucasian individuals with known MBL serum concentrations. The additional 5′ variants were in strong linkage to the elements of the ‘secretor haplotypes’; functional alleles B, C and D also lie on restricted haplotypes. Four variants in the 3′ block (Ex4-1483T>C, Ex4-1067G>A, Ex4-901G>A and Ex4-710G>A) are components of a distinct haplotype block. The results of this study suggest that additional 5′ variants as well as markers of distinct 3′ haplotype blocks in MBL2 may contribute to circulating protein levels, but further studies are required to confirm these observations. Last, there could be a selective advantage for diversification of the 3′ region of the gene.Electronic Supplementary Material Supplementary material is available for this article at     

Current advances in unraveling the function of the Werner syndrome protein

Werner syndrome (WS) is an autosomal recessive premature aging disease manifested by the mimicry of age-related phenotypes such as atherosclerosis, arteriosclerosis, cataracts, osteoporosis, soft tissue calcification, premature thinning, graying, and loss of hair, as well as a high incidence of some types of cancers. The gene product defective in WS, WRN, is a member of the RecQ family of DNA helicases that are widely distributed in nature and believed to play central roles in genomic stability of organisms ranging from prokaryotes to mammals. Interestingly, WRN is a bifunctional protein that is exceptional among RecQ helicases in that it also harbors an exonuclease activity. Furthermore, it preferentially operates on aberrant DNA structures believed to exist in vivo as intermediates in specific DNA transactions such as replication (forked DNA), recombination (Holliday junction, triplex and tetraplex DNA), and repair (partial duplex with single stranded bubble). In addition, WRN has been shown to physically and functionally interact with a variety of DNA-processing proteins, including those that are involved in resolving alternative DNA structures, repair DNA damage, and provide checkpoints for genomic stability. Despite significant research activity and considerable progress in understanding the biochemical and molecular genetic function of WRN, the in vivo molecular pathway(s) of WRN remain elusive. The following review focuses on the recent advances in the biochemistry of WRN and considers the putative in vivo functions of WRN in light of its many protein partners.