Lividins: Novel antimicrobial peptide homologs from the skin secretion of the Chinese Large Odorous frog, Rana (Odorrana) livida: Identification by “shotgun” cDNA cloning and sequence analysis.

Odorous frogs of the sub-genus Odorrana are of oriental distribution, and are so called due to the foul smell of their defensive skin secretions released from specialized skin glands following stress or predator attack. Here we report the application of a “shotgun” skin secretion cDNA library cloning technique which can rapidly expedite identification of secretion bioactive peptides. From a library constructed from the skin secretion of the Large Chinese Odorous frog, Rana (Odorrana) livida, we have identified four novel peptides whose primary structures were deduced initially from cloned precursors. Subsequently, mature peptides were located in and structurally characterized from reverse phase HPLC fractions of skin secretion. Named lividins 1–4, these were found to be structural homologs of known antimicrobial peptide families from Rana frogs. Rapid identification of novel peptides can thus be rapidly achieved using this non-invasive, non-destructive technology and the extensive similarities revealed between antimicrobial peptide precursor organization and nucleic acid sequences would lend support to the hypothesis that they have a common ancestral origin.

Identification and functional analysis of a novel bradykinin inhibitory peptide in the venoms of New World Crotalinae pit vipers.

A novel undecapeptide has been isolated and structurally characterized from the venoms of three species of New World pit vipers from the subfamily, Crotalinae. These include the Mexican moccasin (Agkistrodon bilineatus), the prairie rattlesnake (Crotalus viridis viridis), and the South American bushmaster (Lachesis muta). The peptide was purified from all three venoms using a combination of gel permeation chromatography and reverse-phase HPLC. Automated Edman degradation sequencing and MALDI-TOF mass spectrometry established its peptide primary structure as: Thr-Pro-Pro-Ala-Gly-Pro-Asp-Val-Gly-Pro-Arg-OH, with a non-protonated molecular mass of 1063.18 Da. A synthetic replicate of the peptide was found to be an antagonist of bradykinin action at the rat vascular B2 receptor. This is the first bradykinin inhibitory peptide isolated from snake venom. Database searching revealed the peptide to be highly structurally related (10/11 residues) with a domain residing between the bradykinin-potentiating peptide and C-type natriuretic peptide domains of a recently cloned precursor from tropical rattlesnake (Crotalus durissus terrificus) venom gland. BIP thus represents a novel biological entity from snake venom.

Dietary glycaemic index, glycaemic load and endometrial and ovarian cancer risk: a systematic review and meta-analysis.

Long-term consumption of a high glycaemic index (GI) or glycaemic load (GL) diet may lead to chronic hyperinsulinaemia, which is a potential risk factor for cancer. To date, many studies have examined the association between GI, GL and cancer risk, although results have been inconsistent, therefore our objective was to conduct a systematic review of the literature. Medline and Embase were systematically searched using terms for GI, GL and cancer to identify studies published before December 2007. Random effects meta-analyses were performed for endometrial cancer, combining maximally adjusted results that compared risk for those in the highest versus the lowest category of intake. Separate analysis examined risk by body mass index categories. Five studies examining GI and/or GL intake and endometrial cancer risk were identified. Pooled effect estimates for endometrial cancer showed an increased risk for high GL consumers (RR 1.20; 95% CI: 1.06-1.37), further elevated in obese women (RR 1.54; 95% CI: 1.18-2.03). No significant associations were observed for GI. Only two studies examined ovarian cancer and therefore no meta-analysis was performed, but results indicate positive associations for GL also. A high GL, but not a high GI, diet is positively associated with the risk of endometrial cancer, particularly among obese women. © 2008 Cancer Research UK All rights reserved.

Analyticity of smooth eigenfunctions and spectral analysis of the Gauss map

We provide a sufficient condition of analyticity of infinitely differentiable eigenfunctions of operators of the form Uf(x) = integral a(x, y) f(b( x, y)) mu(dy) acting on functions f: [u, v] --> C ( evolution operators of one-dimensional dynamical systems and Markov processes have this form). We estimate from below the region of analyticity of the eigenfunctions and apply these results for studying the spectral properties of the Frobenius-Perron operator of the continuous fraction Gauss map. We prove that any infinitely differentiable eigenfunction f of this Frobenius-Perron operator, corresponding to a non-zero eigenvalue admits a (unique) analytic extension to the set C\(-infinity, 1]. Analyzing the spectrum of the Frobenius Perron operator in spaces of smooth functions, we extend significantly the domain of validity of the Mayer and Ropstorff asymptotic formula for the decay of correlations of the Gauss map.

Flatworm nerve-muscle: structural and functional analysis

Platyhelminthes occupy a unique position in nerve-muscle evolution, being the most primitive of metazoan phyla. Essentially, their nervous system consists of an archaic brain and associated pairs of longitudinal nerve cords cross-linked as an orthogon by transverse commissures. Confocal imaging reveals that these central nervous system elements are in continuity with an array of peripheral nerve plexuses which innervate a well-differentiated grid work of somatic muscle as well as a complexity of myofibres associated with organs of attachment, feeding, and reproduction. Electrophysiological studies of flatworm muscles have exposed a diversity of voltage-activated ion channels that influence muscle contractile events. Neuronal cell types are mainly multi- and bi-polar and highly secretory in nature, producing a heterogeneity of vesicular inclusions whose contents have been identified cytochemically to include all three major types of cholinergic, aminergic, and peptidergic messenger molecules. A landmark discovery in flatworm neurobiology was the biochemical isolation and amino acid sequencing of two groups of native neuropeptides: neuropeptide F and FMRFamide-related peptides (FaRPs). Both families of neuropeptide are abundant and broadly distributed in platyhelminths, occurring in neuronal vesicles in representatives of all major flatworm taxa. Dual localization studies have revealed that peptidergic and cholinergic substances occupy neuronal sets separate from those of serotoninergic components. The physiological actions of neuronal messengers in flatworms are beginning to be established, and where examined, FaRPs and 5-HT are myoexcitatory, while cholinomimetic substances are generally inhibitory. There is immunocytochemical evidence that FaRPs and 5-HT have a regulatory role in the mechanism of egg assembly. Use of muscle strips and (or) muscle fibres from free-living and parasitic flatworms has provided baseline information to indicate that muscle responses to FaRPs are mediated by a G-protein-coupled receptor, and that the signal transduction pathway for contraction involves the second messengers cAMP and protein kinase C.

Effect of interleukin-6 polymorphisms on human longevity: A systematic review and meta-analysis

Several studies have assessed changes in frequency of -174 interleukin (IL)-6 single nucleotide polymorphism (SNP) with age. If IL-6 tracks with disability and age-related diseases, then there should be reduction, in the oldest old, of the frequency of homozgyous GG subjects, who produce higher IL-6 levels. However, discordant results have been obtained. To explore the relationship between this polymorphism and longevity, we analyzed individual data on long-living subjects and controls from eight case-control studies conducted in Europeans, using meta-analysis. There was no significant difference in the IL-6 genotype between the oldest old and controls (Odds Ratio [OR]=0.96; 95% C.I.: 0.77-1.20; p=0.71), but there was significant between-study heterogeneity (I(2)=55.5%). In a subgroup analyses when male centenarians from the three Italian studies were included, the frequency of the IL-6 -174 GG genotype was significantly lower than the other genotypes (OR=0.49; 95% C.I.: 0.31-0.80; p=0.004), with no evidence of heterogeneity (I(2)=0%). Our data supports a negative association between the GG genotype of IL-6 SNP and longevity in Italian centenarians, with males who carry the genotype being two times less likely to reach extreme old age compared with subjects carrying CC or CG genotypes. These findings were not replicated in other European groups suggesting a possible interaction between genetics, sex and environment in reaching longevity.

Dietary glycaemic index, glycaemic load and breast cancer risk: a systematic review and meta-analysis

This systematic review aimed to examine if an association exists between dietary glycaemic index (GI) and glycaemic load (GL) intake and breast cancer risk. A systematic search was conducted in Medline and Embase and identified 14 relevant studies up to May 2008. Adjusted relative risk estimates comparing breast cancer risk for the highest versus the lowest category of GI/GL intake were extracted from relevant studies and combined in meta-analyses using a random-effects model. Combined estimates from six cohort studies show non-significant increased breast cancer risks for premenopausal women (relative risk (RR) 1.14, 95% CI 0.95-1.38) and postmenopausal women (RR 1.11, 95% CI 0.99-1.25) consuming the highest versus the lowest category of GI intake. Evidence of heterogeneity hindered analyses of GL and premenopausal risk, although most studies did not observe any significant association. Pooled cohort study results indicated no association between postmenopausal risk and GL intake (RR 1.03, 95% CI 0.94-1.12). Our findings do not provide strong support of an association between dietary GI and GL and breast cancer risk. © 2008 Cancer Research UK.


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Glycemic index, glycemic load, and risk of digestive tract neoplasms: a systematic review and meta-analysis

Background: Habitual consumption of diets with a high glycemic index (GI) and a high glycemic load (GL) may influence cancer risk via hyperinsulinemia and the insulin-like growth factor axis.
Objective: The objective was to conduct a systematic review to assess the association between GI, GL, and risk of digestive tract cancers.
Design: Medline and Embase were searched for relevant publications from inception to July 2008. When possible, adjusted results from a comparison of cancer risk of the highest compared with the lowest category of GI and GL intake were combined by using random-effects meta-analyses.
Results: Cohort and case-control studies that examined the risk between GI or GL intake and colorectal cancer (n = 12) and adenomas (n = 2), pancreatic cancer (n = 6), gastric cancer (n = 2), and squamous-cell esophageal carcinoma (n = 1) were retrieved. Most case-control studies observed positive associations between GI and GL intake and these cancers. However, pooled cohort study results showed no associations between colorectal cancer risk and GI intake [relative risk (RR): 1.04; 95% CI: 0.92, 1.12; n = 7 studies] or GL intake (RR: 1.06; 95% CI: 0.95, 1.17; n = 8 studies). Furthermore, no significant associations were observed in meta-analyses of cohort study results of colorectal cancer subsites and GI and GL intake. Similarly, no significant associations emerged between pancreatic cancer risk and GI intake (RR: 0.99; 95% CI: 0.83, 1.19; n = 5 studies) or GL intake (RR: 1.01; 95% CI: 0.86, 1.19; n = 6 studies) in combined cohort studies.
Conclusions: The findings from our meta-analyses indicate that GI and GL intakes are not associated with risk of colorectal or pancreatic cancers. There were insufficient data available regarding other digestive tract cancers to make any conclusions about GI or GL intake and risk.