ABSTRACT
Cyclic peptides are highly valued tools in biomedical research. In many cases, they show higher receptor affinity, enhanced biological activity, and improved serum stability. Technical ...difficulties in producing cyclic peptides, especially larger ones, in appreciable yields have precluded a prolific use in biomedical research. Here, we describe a novel and efficient cyclization method that uses the peptidyl‐transferase activity of the Staphylococcus aureus enzyme sortase A to cyclize linear synthetic precursor peptides. As a model, we used histatin 1, a 38‐mer salivary peptide with motogenic activity. Chemical cyclization of histatin 1 resulted in ≤3% yields, whereas sortase‐mediated cyclization provided a yield of >90%. The sortase‐cyclized peptide displayed a maximum wound closure activity at 10 nM, whereas the linear peptide displayed maximal activity at 10 μM. Circular dichroism and NMR spectroscopic analysis of the linear and cyclic peptide in solution showed no evidence for conformational changes, suggesting that structural differences due to cyclization only became manifest when these peptides were located in the binding domain of the receptor. The sortase‐based cyclization technology provides a general method for easy and efficient manufacturing of large cyclic peptides.—Bolscher, J. G. M., Oudhoff, M. J., Nazmi, K., Antos, J. M., Guimaraes, C. P., Spooner, E., Haney, E. F., Garcia‐Vallejo, J. J., Vogel, H. J., van't Hof, W., Ploegh, H. L., Veerman. E. C. I. Sortase A as a tool for high‐yield histatin cyclization. FASEB J. 25, 2650–2658 (2011). www.fasebj.org
The population dynamics of shade-tolerant tree species often includes a seedling bank — small trees persisting in the understory until canopy opening allows increased height growth. We studied the ...growth and morphology of 0.1–1.3 m tall Abies amabilis Douglas ex J. Forbes trees in the seedling bank of an ancient (>1300 years old) subalpine conifer forest on Vancouver Island, western Canada. We determined rates of height growth by counting growth rings at 10 cm intervals along the main stem and assessed crown morphology by measuring the length and location of each branch along the main stem. These small trees were very old (mean basal ring count, 112 years) and grew very slowly, taking on average 170 years to reach a height of 1 m. Instead of the typical conical form of open-grown Abies Mill., seedling bank individuals had flat crowns. Most branches were near the top of the main stem. The maximum distance along the main stem plus a branch was 1.6 times the main stem length, indicating that resource allocation is focused on lateral growth. The ability to grow slowly and adjust crown morphology allows seedling bank trees to persist for decades to centuries and to retain the possibility of release and growth into the canopy.
Celotno besedilo
Dostopno za:
BF, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The objective of this study was to describe the oral health status of Cystic Fibrosis (CF) children in a US facility.
Twenty CF children ages 6-18 were recruited from Children's Hospital of Wisconsin ...Pulmonary Clinic. Parents completed a health questionnaire. Clinical examinations checked dental caries using the dmft/DMFT index, dental hygiene using the Simplified Greene-Vermillion Index (DI-S), gingival inflammation using the Community Periodontal Index of Treatment Needs, and enamel defects using the modified Developmental Defects of Enamel Index.
The majority (90%) brush twice a day, 65% consume sugary snacks, and 70% visit the dentist every 6 months. Clinically, they presented DMFT 0.25 and dmft 0.90, fair oral hygiene with DI-S 1.02, 75% had mild gingivitis and 50% had enamel defects. The more antibiotics they took, significantly more frequent (p=0.007) and more severe (p=0.017) enamel defects were noted. Similar trend was found between the number of surgeries and the presence of enamel defects (p=0.076) and dental caries (p=0.028).
Within the limitations of this study, CF patients were found to be at oral health risk due to the high prevalence of dental enamel defects. Oral health for CF children should be part of the multidisciplinary care.
Postnatal cardiac myocytes respond to stress signals by hypertrophic growth and activation of a fetal gene program. Recently, we showed that class II histone deacetylases (HDACs) suppress cardiac ...hypertrophy, and mice lacking the class II HDAC, HDAC9, are sensitized to hypertrophic signals. To further define the roles of HDACs in cardiac hypertrophy, we analyzed the effects of HDAC inhibitors on the responsiveness of primary cardiomyocytes to hypertrophic agonists. Paradoxically, HDAC inhibitors imposed a dose-dependent blockade to hypertrophy and fetal gene activation. We conclude that distinct HDACs play positive or negative roles in the control of cardiomyocyte hypertrophy. HDAC inhibitors are currently being tested in clinical trials as anti-cancer agents. Our results suggest that these inhibitors may also hold promising clinical value as therapeutics for cardiac hypertrophy and heart failure.
Wind-powered recreational (WPR) activities are increasingly popular and occur in many areas of high conservation value. Possible impacts are poorly understood; existing reviews do not generally ...include recent widespread forms of WPR or have narrow taxonomic/ecological scopes. We identify the coastal ecosystems/wildlife that may interact with WPR and potential impacts: a) noise, movement and other stimuli, b) direct contact, c) disruption of substrates, and d) transport of pests. Almost all available evidence on impacts involves coastal birdlife, specifically their escape responses. Most studies are a) non-peer reviewed, largely anecdotal or otherwise limited in scope and b) from temperate locations. Sustainable use of WPR craft is required despite the prevailing information gaps. We suggest a precautionary, proactive approach which likely requires a combination of site-based management, plus policy and education initiatives.
This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (??) in the e.sup.+ or -μ.sup.∓ continuum using 2.1 fb.sup.-1 of data collected by the ATLAS detector ...in square root of s = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95% C.L. are calculated as a function of the scalar top mass (m.sub.??). The upper limits on the production cross section for pp → eμX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for m.sub.?? = 95 GeV to 30 fb for m.sub.?? = 1000 GeV.
Type III interferon, or interferon lambda (IFNλ) is a crucial antiviral cytokine induced by influenza infection. While IFNλ is important for anti-viral host defense, published data demonstrate that ...IFNλ is pathogenic during influenza/bacterial super-infection. It is known that polymorphisms in specific IFNλ genes affect influenza responses, but the effect of IFNλ subtypes on bacterial super-infection is unknown.
Using an established model of influenza, Staphylococcus aureus super-infection, we studied IFNλ3-/- and control mice to model a physiologically relevant reduction in IFNλ and to address its role in super-infection.
Surprisingly, IFNλ3-/- mice did not have significantly lower total IFNλ than co-housed controls, and displayed no change in viral or bacterial clearance. Importantly, both control and IFNλ3-/- mice displayed a positive correlation between viral burden and total IFNλ in the bronchoalveolar lavage during influenza/bacterial super-infection, suggesting that higher influenza viral burden drives a similar total IFNλ response regardless of IFNλ3 gene integrity. Interestingly, total IFNλ levels positively correlated with bacterial burden, while viral burden and bronchoalveolar lavage cellularity did not.
These data suggest IFNλ2 can compensate for IFNλ3 to mount an effective antiviral and defense, revealing a functional redundancy in these highly similar IFNλ subtypes. Further, the IFNλ response to influenza, as opposed to changes in cellular inflammation or viral load, significantly correlates with susceptibility to bacterial super-infection. Moreover, the IFNλ response is regulated and involves redundant subtypes, suggesting it is of high importance to pulmonary pathogen defense.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In response to stress signals, postnatal cardiomyocytes undergo hypertrophic growth accompanied by activation of a fetal gene program, assembly of sarcomeres, and cellular enlargement. We show that ...hypertrophic signals stimulate the expression and transcriptional activity of myocardin, a cardiac and smooth muscle–specific coactivator of serum response factor (SRF). Consistent with a role for myocardin as a transducer of hypertrophic signals, forced expression of myocardin in cardiomyocytes is sufficient to substitute for hypertrophic signals and induce cardiomyocyte hypertrophy and the fetal cardiac gene program. Conversely, a dominant-negative mutant form of myocardin, which retains the ability to associate with SRF but is defective in transcriptional activation, blocks cardiomyocyte hypertrophy induced by hypertrophic agonists such as phenylephrine and leukemia inhibitory factor. Myocardin-dependent hypertrophy can also be partially repressed by histone deacetylase 5, a transcriptional repressor of myocardin. These findings identify myocardin as a nuclear effector of hypertrophic signaling pathways that couples stress signals to a transcriptional program for postnatal cardiac growth and remodeling.
Introduced birds are a pervasive and dominant element of urban ecosystems. We examined the richness and relative abundance of introduced bird species in small (1-5 ha) medium (6-15 ha) and large (>15 ...ha) remnants of native vegetation within an urban matrix. Transects were surveyed during breeding and non-breeding seasons. There was a significant relationship between introduced species richness and remnant size with larger remnants supporting more introduced species. There was no significant difference in relative abundance of introduced species in remnants of different sizes. Introduced species, as a proportion of the relative abundance of the total avifauna (native and introduced species), did not vary significantly between remnants of differing sizes. There were significant differences in the composition of introduced bird species between the different remnant sizes, with large remnants supporting significantly different assemblages than medium and small remnants. Other variables also have substantial effects on the abundance of introduced bird species. The lack of significant differences in abundance between remnant sizes suggests they were all equally susceptible to invasion. No patches in the urban matrix are likely to be unaffected by introduced species. The effective long-term control of introduced bird species is difficult and resources may be better spent managing habitat in a way which renders it less suitable for introduced species (e.g. reducing areas of disturbed ground and weed dominated areas).
Environmental stresses converge on the mitochondria that can trigger or inhibit cell death. Excitable, postmitotic cells, in response to sublethal noxious stress, engage mechanisms that afford ...protection from subsequent insults. We show that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria. Cell protection that exhibits a memory (preconditioning) results from triggered mitochondrial swelling that causes enhanced substrate oxidation and ROS production, leading to redox activation of PKC, which inhibits glycogen synthase kinase-3beta (GSK-3beta). Alternatively, receptor tyrosine kinase or certain G protein-coupled receptor activation elicits cell protection (without mitochondrial swelling or durable memory) by inhibiting GSK-3beta, via protein kinase B/Akt and mTOR/p70(s6k) pathways, PKC pathways, or protein kinase A pathways. The convergence of these pathways via inhibition of GSK-3beta on the end effector, the permeability transition pore complex, to limit MPT induction is the general mechanism of cardiomyocyte protection.
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