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

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

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

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

Hypoxia-inducible factor-1α and -2α are expressed in most rectal cancers but only hypoxia-inducible factor-1α is associated with prognosis

The hypoxia-mediated response of tumours is a major determining factor in growth and metastasis. Understanding tumour biology under hypoxic conditions is crucial for the development of antiangiogenic therapy. Using one of the largest cohorts of rectal adenocarcinomas to date, this study investigated hypoxia-inducible factor-1α (HIF-1α) and HIF-2α protein expression in relation to rectal cancer recurrence and cancer-specific survival. Patients (n=90) who had undergone surgery for rectal adenocarcinoma, with no prior neoadjuvant therapy or metastatic disease, and for whom adequate follow-up data were available were selected. Microvessel density (MVD), HIF-1α and HIF-2α expressions were assessed immunohistologically with the CD34 antibody for vessel identification and the NB100-131B and NB100-132D3 antibodies for HIF-1α and HIF-2α, respectively. In a multifactorial analysis, results were correlated with tumour stage, recurrence rate and long-term survival. Microvessel density was higher across T and N stages (P<0.001) and associated with poor survival (hazard ratio (HR)=8.7, P<0.005) and decreased disease-free survival (HR=4.7, P<0.005). hypoxia-inducible factor-1α and -2α were expressed in >50% of rectal cancers (HIF-1α, 54%, 48/90; HIF-2α, 64%, 58/90). HIF-1α positivity was associated with both TNM stage (P<0.05) and vascular invasion (P<0.005). In contrast, no associations were shown between HIF-2α expression and any pathological features, and HIF-1α positivity had no effect on outcome. The study showed an independent association between HIF-1α expression and advanced TNM stage with poor outcome. Our results indicate that HIF-1α, but not HIF-2α, might be used as a marker of prognosis, in addition to methods currently used, to enhance patient management

General practice vs surgical-based follow-up for patients with colon cancer: randomised controlled trial

This trial examined the optimal setting for follow-up of patients after treatment for colon cancer by either general practitioners or surgeons. In all, 203 consenting patients who had undergone potentially curative treatment for colon cancer were randomised to follow-up by general practitioners or surgeons. Follow-up guidance recommended three monthly clinical review and annual faecal occult blood tests (FOBT) and were identical in both study arms. Primary outcome measures (measured at baseline, 12 and 24 months were (1) quality of life, SF-12; physical and mental component scores, (2) anxiety and depression: Hospital Anxiety and Depression Scale and (3) patient satisfaction: Patient Visit-Specific Questionnaire. Secondary outcomes (at 24 months) were: investigations, number and timing of recurrences and deaths. In all, 170 patients were available for follow-up at 12 months and 157 at 24 months. At 12 and 24 months there were no differences in scores for quality of life (physical component score, P=0.88 at 12 months; P=0.28 at 24 months: mental component score, P=0.51, P=0.47; adjusted), anxiety (P=0.72; P=0.11) depression (P=0.28; P=0.80) or patient satisfaction (P=0.06, 24 months). General practitioners ordered more FOBTs than surgeons (rate ratio 2.4, 95% CI 1.4–4.4), whereas more colonoscopies (rate ratio 0.7, 95% CI 0.5–1.0), and ultrasounds (rate ratio 0.5, 95% CI 0.3–1.0) were undertaken in the surgeon-led group. Results suggest similar recurrence, time to detection and death rates in each group. Colon cancer patients with follow-up led by surgeons or general practitioners experience similar outcomes, although patterns of investigation vary