Inhibition of NO-synthase and degranulation of rat omental mast cells in vitro

Mast cell amines, platelet-activating factor (PAF), thromboxanes and leukotrienes have been shown to be released during nitric oxide-synthase inhibition in the rat intestine. Mast cells in rat isolated omentum (OMCs) or isolated from the rat peritoneal cavity (PMCs) have been used here to investigate the relationship(s) between these agents. N-nitro-L-arginine methyl ester (L-NAME, 100 μM) caused some degranulation of OMCs, but no enhancement of histamine release from PMCs. PAF (5 μM) and U46619 (1 μM) degranulated OMCs and enhanced histamine release from PMCs. Pre-treatment of the omentum with BN52021 (10 μM) inhibited degranulation of OMCs in response to L-NAME, PAF or U46619. Pretreatment with 1-benzylimidazole (5 or 50 μM) inhibited the effect of L-NAME but not that of PAF. Indomethacin (1 μM) or sodium nitroprusside (10 μM) also inhibited the effects of L-NAME, but nordihydroguaiaretic acid (30 μM) did not. In PMCs BN52021 inhibited PAF-induced, but not U46619-induced, release of histamine. These results suggest that inhibition of nitric oxidesynthase in the omentum by L-NAME allows thromboxanes to release PAF, which in turn degranulates and releases histamine from OMCs

Possible bi-directional link between ETA receptors and protein kinase C in rat blood vessels

Possible links have been investigated between activation of protein kinase C (PKC) and endothelin (ET) production by small blood vessels. Perfusion pressures were recorded from rat isolated mesenteric artery, with or without the small intestine attached, before and after addition to the perfusate of either ET-1, ET-3 or the PKC activator 12-deoxyphorbol 13-phenylacetate (DOPPA). Rises in perfusion pressure in response to ET-1 (10−8 M)or DOPPA (10−6 M) were reduced significantly by pre-treatment with either the ETA receptor antagonist PD151242 (10−6 M) or the PKC inhibitor Ro 31-8220 (10−6 M). ET-3 (10−8 M) had a significant, albeit small, effect only when the gut was still attached to the mesentery. Inthis latter preparation ET-1 and DOPPA increased the permeability of villi microvessels to colloidal carbon in the perfusate. This effect of DOPPA was reduced by pre-treatment with either PD151242 or Ro 31-8220, but the effects of ET-1 were reduced significantly only by Ro 31-8220. ET-3 (10−8 M) was without effect. The results suggest a possible bi-directional link between ETA receptors and PKC in the intestinal vasculature

Rat intestinal mast cell amines are released during nitric oxide synthase inhibition in vitro

Inhibition of nitric oxide synthase increases microvascular permeability in rat small intestinal villi. To determine the mechanism(s) whereby this occurs we have perfused the vasculature of rat isolated small intestines with a gelatin-containing physiological salt solution. Inclusion of N-nitro-L-argintne methyl ester (L-NAME, 100 μM) or indomethacin (1 μM) in the perfusate increased leakage of injected colloidal carbon into microvessel walls. Pre-treatment with sodium nitroprusside (10 μM) significantly reduced the effects of both L-NAME and indomethacin, whereas carbacyclin (1 μM) only reduced the effects of indomethacin. PD151242 (1 μM) showed some antagonism towards the effects of L-NAME, but nordihydroguaiaretic acid (3 μM) was inactive. Pre-tment with cyproheptadine (10 μM) reduced the effects of both L-NAME and indomethacin, and also significantly reduced background (control) colloidal carbon leakage. Small intestines from polymixin B-treated rats showed significantly reduced colloidal carbon leakage in response to L-NAME. This suggests that the leakage-enhancing effects of both L-NAME and indomethacin in this preparation may be mediated by mast cell-derived amines

Rate of perfusion modulates colloidal carbon leakage from rat intestinal microvessels in vitro

In order to investigate the effects of varying the rate of flow on endothelial integrity the rat isolated small intestinal vasculature was perfused at 1, 5, 10 or 20 ml/min with a gelatin-containing physiological salt solution (GPSS), followed by an injection of colloidal carbon suspension (CC). Significantly greater microvascular CC leakage occurred at 1 or 5 ml/min than at 10 or 20 ml/ mitt. CC leakage at the two slower rates of flow was reduced by adding red blood cells to the GPSS, suggesting that the microvascular endothelium became hypoxic when perfused with GPSS at 1 or 5 ml/min. After perfusion at 20 ml/min with GPSS containing resiniferatoxin (1 μM) or 5-hydroxytryptamine (100 μM), CC leakage was significantly lower than after similar perfusion at 10 ml/min. Two nitric oxide (NO) synthesis blockers, N-nitro-L-arginine methyl ester (L-NAME, 100 μM) and methylene blue (20 μM), and an NO scavenger CPTIO (100 μM) each increased CC leakage. This suggests that NO was being produced at perfusion rates of 10 or 20 ml/min. Sodium nitroprusside (10 μM), 8-bromo-cGMP (100 μM) and BN52021 (10 μM) each significantly reduced CC leakage in the presence of L-NAME

Durkheim’s totemic principle, shamanism and Southern African San religions

The study reappraised Emile Durkheim’s totemic principle in relation to the origins of religion and culture, using, amongst others, speech act theory and recent southern African epistemologies, especially David Lewis-Williams’ theory of shamanism, potency and altered states of consciousness. The study was text-based, qualitative and interpretive, and used key texts from anthropology, archaeology, history of religion, sociology and philosophy. It outlined Durkheim’s theory of the totemic principle and critiqued it, using performativity, cognitive neuroscience and southern African ethnography. Durkheim’s sociological reduction of God and religion to society and his dismissal of individual psychological experience were criticised. Lewis-Williams’ shamanism, both as a general theory and with particular reference to the San, was explored as an alternative to Durkheim’s totemism, animals playing a central but different function in each system. Although his understanding of performativity and sociopolitical relations in religion was inchoate, Durkheim helped demystify religion and establish social constructionism. He overestimated collective affect and sentiments and underestimated the role played by individual altered states of consciousness in the origin of religion. Contribution: The study critically evaluates Durkheim’s reduction of religion to society using current concepts of performativity, Matthias Guenther’s New Animism and David Lewis-Williams’ revised shamanism, particularly its ideas of trance dance, potency and altered states of consciousness, and posits shamanism rather than totemism as the probable origin of religion

Does observability affect prosociality?

The observation of behaviour is a key theoretical parameter underlying a number of models of prosociality. However, the empirical findings showing the effect of observability on prosociality are mixed. In this meta-analysis, we explore the boundary conditions that may account for this variability, by exploring key theoretical and methodological moderators of this link. We identified 117 papers yielding 134 study level effects (Total N = 788, 164) and found a small but statistically significant, positive association between observability and prosociality (r = .141, 95% CI = .106, .175). Moderator analysis showed that observability produced stronger effects on prosociality (1) in the presence of passive observers (i.e., people whose role was to only observe participants) vs perceptions of being watched, (2) when participants decisions were consequential (vs non-consequential), (3) when the studies were performed in the laboratory (as opposed to in the field/online), (4) when studies used repeated measures (instead of single games) and (5) when studies involved social dilemmas (instead of bargaining games). These effects show the conditions under which observability effects on prosociality will be maximally observed. We describe the theoretical and practical significance of 14 these results

Morphological and molecular description of Ixodes woyliei n. sp. (Ixodidae) with consideration for co-extinction with its critically endangered marsupial host

Background Taxonomic identification of ticks obtained during a longitudinal survey of the critically endangered marsupial, Bettongia penicillata Gray, 1837 (woylie, brush-tailed bettong) revealed a new species of Ixodes Latrielle, 1795. Here we provide morphological data for the female and nymphal life stages of this novel species (Ixodes woyliei n. sp.), in combination with molecular characterisation using the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). In addition, molecular characterisation was conducted on several described Ixodes species and used to provide phylogenetic context. Results Ixodes spp. ticks were collected from the two remaining indigenous B. penicillata populations in south-western Australia. Of 624 individual B. penicillata sampled, 290 (47%) were host to ticks of the genus Ixodes; specifically I. woyliei n. sp., I. australiensis Neumann, 1904, I. myrmecobii Roberts, 1962, I. tasmani Neumann, 1899 and I. fecialis Warburton & Nuttall, 1909. Of these, 123 (42%) were host to the newly described I. woyliei n. sp. In addition, 268 individuals from sympatric marsupial species (166 Trichosurus vulpecula hypoleucus Wagner, 1855 (brushtail possum), 89 Dasyurus geoffroii Gould, 1841 (Western quoll) and 13 Isoodon obesulus fusciventer Gray, 1841 (southern brown bandicoot)) were sampled for ectoparasites and of these, I. woyliei n. sp. was only found on two I. o. fusciventer. Conclusions Morphological and molecular data have confirmed the first new Australian Ixodes tick species described in over 50 years, Ixodes woyliei n. sp. Based on the long-term data collected, it appears this tick has a strong predilection for B. penicillata, with 42% of Ixodes infections on this host identified as I. woyliei n. sp. The implications for this host-parasite relationship are unclear but there may be potential for a future co-extinction event. In addition, new molecular data have been generated for collected specimens of I. australiensis, I. tasmani and museum specimens of I. victoriensis Nuttall, 1916, which for the first time provides molecular support for the subgenus Endopalpiger Schulze, 1935 as initially defined. These genetic data provide essential information for future studies relying on genotyping for species identification or for those tackling the phylogenetic relationships of Australian Ixodes species