A revised structure for alkaloid 235C isolated from skin extracts of mantellid (Mantella) frogs of Madagascar

Madagascan frogs of the mantellid genus Mantella have been a rich source of alkaloids derived from dietary arthropods. Two species of frogs, inhabiting swamp forest, contain a unique set of alkaloids, previously proposed, based only on GC-MS and GC-FTIR data, to represent dehydro analogues of the homopumiliotoxins. The major alkaloid of this set, alkaloid 235C (2), now has been isolated in sufficient quantities (ca. 0.3 mg) to allow determination of the structure by NMR analysis. The structure of alkaloid 235C proved to be a 7,8-dehydro-8-desmethylpumiliotoxin. A comparison is presented between the mass, infrared, and H-1 NMR spectra of 235C (2) and a synthetic dehydrohomopumiliotoxin (1), initially proposed incorrectly as the structure for 235C.

Regenerative Medicine and New Labour Life Science Policy: Rhetorics of Success, Narratives of Sustainability and Survival

Advances in stem cell science and tissue engineering are being turned into applications and products through a novel medical paradigm known as regenerative medicine. This paper begins by examining the vulnerabilities and risks encountered by the regenerative medicine industry during a pivotal moment in its scientific infancy: the 2000s. Under the auspices of New Labour, British medical scientists and life science innovation firms associated with regenerative medicine, received demonstrative rhetorical pledges of support, aligned with the publication of a number of government initiated reports presaged by Bioscience 2015: Improving National Health, Increasing National Wealth. The Department of Health and the Department of Trade and Industry (and its successors) held industry consultations to determine the best means by which innovative bioscience cultures might be promoted and sustained in Britain. Bioscience 2015 encapsulates the first chapter of this sustainability narrative. By 2009, the tone of this storyline had changed to one of survivability. In the second part of the paper, we explore the ministerial interpretation of the ‘bioscience discussion cycle’ that embodies this narrative of expectation, using a computer-aided content analysis programme. Our analysis notes that the ministerial interpretation of these reports has continued to place key emphasis upon the distinctive and exceptional characteristics of the life science industries, such as their ability to perpetuate innovations in regenerative medicine and the optimism this portends – even though many of the economic expectations associated with this industry have remained unfulfilled.

Estimation of survival rate and extinction probability for stage-structured populations with overlapping life stages

The development of methods providing reliable estimates of demographic parameters (e. g., survival rates, fecundity) for wild populations is essential to better understand the ecology and conservation requirements of individual species. A number of methods exist for estimating the demographics of stage-structured populations, but inherent mathematical complexity often limits their uptake by conservation practitioners. Estimating survival rates for pond-breeding amphibians is further complicated by their complex migratory and reproductive behaviours, often resulting in nonobservable states and successive cohorts of eggs and tadpoles. Here we used comprehensive data on 11 distinct breeding toad populations (Bufo calamita) to clarify and assess the suitability of a relatively simple method [the Kiritani-Nakasuji-Manly (KNM) method] to estimate the survival rates of stage-structured populations with overlapping life stages. The study shows that the KNM method is robust and provides realistic estimates of amphibian egg and larval survival rates for species in which breeding can occur as a single pulse or over a period of several weeks. The study also provides estimates of fecundity for seven distinct toad populations and indicates that it is essential to use reliable estimates of fecundity to limit the risk of under- or overestimating the survival rates when using the KNM method. Survival and fecundity rates for B. calamita populations were then used to define population matrices and make a limited exploration of their growth and viability. The findings of the study recently led to the implementation of practical conservation measures at the sites where populations were most vulnerable to extinction. © 2010 The Society of Population Ecology and Springer.

Cell survival responses after exposure to modulated radiation fields.

In the present study survival responses were determined in cells with differing radiosensitivity, specifically primary fibroblast (AG0-1522B), human breast cancer (MDA-MB-231), human prostate cancer (DU-145) and human glioma (T98G) cells, after exposure to modulated radiation fields delivered by shielding 50% of the tissue culture flask. A significant decrease (P < 0.05) in cell survival was observed in the shielded area, outside the primary treatment field (out-of-field), that was lower than predicted when compared to uniform exposures fitted to the linear-quadratic model. Cellular radiosensitivity was demonstrated to be an important factor in the level of response for both the in- and out-of-field regions. These responses were shown to be dependent on secretion-mediated intercellular communication, because inhibition of cellular secreted factors between the in- and out-of-field regions abrogated the response. Out-of-field cell survival was shown to increase after pretreatment of cells with agents known to inhibit factors involved in mediating radiation-induced bystander signaling (aminoguanidine, DMSO or cPTIO). These data illustrate a significant decrease in survival out-of-field, dependent upon intercellular communication, in several cell lines with varying radiosensitivity after exposure to a modulated radiation field. This study provides further evidence for the importance of intercellular signaling in modulated exposures, where dose gradients are present, and may inform the refinement of established radiobiological models to facilitate the optimization of advanced radiotherapy treatment plans.

Functional peptidomics of amphibian skin secretion: A novel Kunitz-type chymotrypsin inhibitor from the African hyperoliid frog, Kassina senegalensis

Amphibian skin secretions are, for the most part, complex peptidomes. While many peptide components have been biologically- and structurally-characterised into discrete "families", some of which are analogues of endogenous vertebrate regulatory peptides, a substantial number are of unique structure and unknown function. Among the components of these secretory peptidomes is an array of protease inhibitors. Inhibitors of trypsin are of widespread occurrence in different taxa and are representative of many established structural classes, including Kunitz, Kazal and Bowman-Birk. However, few protease inhibitors with activity against other specific proteases have been described from this source. Here we report for the first time, the isolation and structural characterisation of an inhibitor of chymotrypsin of Kunitz-type from the skin secretion of the African hyperoliid frog, Kassina senegalensis. To this end, we employed a functional peptidomic approach. This scheme involves fractionation of the peptidome, functional end-point screening, structural characterisation of resultant actives followed by molecular cloning of biosynthetic precursor-encoding cDNA(s). The novel mature and active polypeptide identified consisted of 62 amino acid residues (average molecular mass 6776.24 Da), of which 6 were positionally-conserved cysteines. The P(1) position within the active site was occupied by a phenylalanyl residue. Bioinformatic analysis of the sequence using BLAST, revealed a structural similarity to Kunitz-type chymotrypsin inhibitors from other organisms, ranging from silkworms to snakes.

Identification and molecular cloning of a novel amphibian Bowman Birk-type trypsin inhibitor from the skin of the Hejiang Odorous Frog; Odorrana hejiangensis.

In this study, an amphibian (Odorrana hejiangensis) skin extract was fractionated by reverse phase HPLC and fractions were screened for trypsin inhibitory activity. Using this initial approach, a novel trypsin inhibitory peptide was detected with an apparent protonated molecular mass of 1804.83Da, as determined by MALDI-TOF mass spectrometry. It was named Hejiang trypsin inhibitor (HJTI) in accordance. The primary structure of the biosynthetic precursor of HJTI was deduced from a cDNA sequence cloned from a skin-derived cDNA library. The primary structure of the encoded predicted mature active peptide was established as: GAPKGCWTKSYPPQPCS (non-protonated monoisotopic molecular mass - 1802.81Da). On the basis of this unequivocal amino acid sequence, a synthetic replicate was synthesized by solid phase Fmoc chemistry. This replicate displayed a moderately potent trypsin inhibition with a K(i) of 388nM. Bioinformatic analysis of the primary structure of this peptide indicated that it was a member of the Bowman-Birk family of protease inhibitors. The substitutions of Gln-14 and Ser-17 by Lys, resulted in an increase in cationicity and a small increase in potency to a K(i) value of 218nM. Neither HJTI nor its synthetic analog, possessed any significant antimicrobial activity.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in cancer progression and survival: a systematic review

Objective: To investigate the association between angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) and disease progression and survival in cancer patients.

Methods: Using terms for cancer and ACEIs/ARBs, MEDLINE, EMBASE and Web of Science were systematically searched for observational/interventional studies that used clinically relevant outcomes for cancer progression and survival.

Results: Ten studies met the inclusion criteria. Two studies showed a significant improvement in overall survival (OS) with ACEI/ARB use among patients with advanced pancreatic (HR 0.52, 95% CI 0.29–0.88) and non-small cell lung cancer (HR 0.56, 95% CI 0.33–0.95). An improvement in progression-free survival (PFS) was also reported for pancreatic cancer patients (HR 0.58, 95% CI 0.34–0.95) and patients with renal cell carcinoma (HR 0.54, p = 0.02). ACEI/ARB use was protective against breast cancer recurrence (HR 0.60, 95% CI 0.37–0.96), colorectal cancer distant metastasis (OR 0.22, 95% CI 0.08–0.65) and prostate specific antigen (PSA) failure in prostate cancer patients (p = 0.034). One study observed a worse OS (HR 2.01, 95% CI 1.00–4.05) and PFS in ACEI users with multiple myeloma (p = 0.085) while another reported an increased risk of breast cancer recurrence (HR = 1.56, 95% CI 1.02–2.39).

Conclusion: There is some evidence to suggest that ACEI or ARB use may be associated with improved outcomes in cancer patients. Larger, more robust studies are required to explore this relationship further.

Glacial Survival of Boreal Trees in Northern Scandinavia

It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west—an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trøndelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andøya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.