Peptide YY and glucagon-like peptide-1 contribute to decreased food intake after Roux-en-Y gastric bypass surgery

BACKGROUND/OBJECTIVES

Exaggerated postprandial secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) may explain appetite reduction and weight loss after Roux-en-Y gastric bypass (RYGB), but causality has not been established. We hypothesized that food intake decreases after surgery through combined actions from GLP-1 and PYY. GLP-1 actions can be blocked using the GLP-1 receptor antagonist Exendin 9-39 (Ex-9), whereas PYY actions can be inhibited by the administration of a dipeptidyl peptidase-4 (DPP-4) inhibitor preventing the formation of PYY_3-36.

SUBJECTS/METHODS

Appetite-regulating gut hormones and appetite ratings during a standard mixed-meal test and effects on subsequent ad libitum food intake were evaluated in two studies: in study 1, nine patients with type 2 diabetes were examined prospectively before and 3 months after RYGB with and without Ex-9. In study 2, 12 RYGB-operated patients were examined in a randomized, placebo-controlled, crossover design on four experimental days with: (1) placebo, (2) Ex-9, (3) the DPP-4 inhibitor, sitagliptin, to reduce formation of PYY_3-36 and (4) Ex-9/sitagliptin combined.

RESULTS

In study 1, food intake decreased by 35% following RYGB compared with before surgery. Before surgery, GLP-1 receptor blockage increased food intake but no effect was seen postoperatively, whereas PYY secretion was markedly increased. In study 2, combined GLP-1 receptor blockage and DPP-4 inhibitor mediated lowering of PYY_3-36 increased food intake by ~20% in RYGB patients, whereas neither GLP-1 receptor blockage nor DPP-4 inhibition alone affected food intake, perhaps because of concomitant marked increases in the unblocked hormone.

CONCLUSIONS

Blockade of actions from only one of the two L-cell hormones, GLP-1 and PYY_3-36, resulted in concomitant increased secretion of the other, probably explaining the absent effect on food intake on these experimental days. Combined blockade of GLP-1 and PYY actions increased food intake after RYGB, supporting that these hormones have a role in decreased food intake postoperatively.

An empirically based steady state friction law and implications for fault stability

Empirically based rate-and-state friction laws (RSFLs) have been proposed to model the dependence of friction forces with slip and time. The relevance of the RSFL for earthquake mechanics is that few constitutive parameters define critical conditions for fault stability (i.e., critical stiffness and frictional fault behavior). However, the RSFLs were determined from experiments conducted at subseismic slip rates (V < 1 cm/s), and their extrapolation to earthquake deformation conditions (V > 0.1 m/s) remains questionable on the basis of the experimental evidence of (1) large dynamic weakening and (2) activation of particular fault lubrication processes at seismic slip rates. Here we propose a modified RSFL (MFL) based on the review of a large published and unpublished data set of rock friction experiments performed with different testing machines. The MFL, valid at steady state conditions from subseismic to seismic slip rates (0.1 µm/s < V < 3 m/s), describes the initiation of a substantial velocity weakening in the 1-20 cm/s range resulting in a critical stiffness increase that creates a peak of potential instability in that velocity regime. The MFL leads to a new definition of fault frictional stability with implications for slip event styles and relevance for models of seismic rupture nucleation, propagation, and arrest.

Modulatory effects of steroid hormones, oxytocin, arachidonic acid, forskolin and cyclic AMP on the expression of aquaporin 1 and aquaporin 5 in the porcine uterus during placentation

Aquaporins (AQPs) are proteins forming trans-membrane channels responsible for water transport. AQP1 and AQP5 are present in structures of the female reproductive system. In the uterus, these AQPs are involved in water movement between the intraluminal, interstitial and capillary compartments and their uterine expression is essential throughout the pregnancy, including its early stages. Thus, the study aimed to assess the influence of P4 (progesterone), E2 (estradiol), OT (oxytocin), AA (arachidonic acid), cAMP and FSK (forskolin) on the AQP1 and AQP5 mRNA and protein expression in the uterine tissue of gilts on Days 30 - 32 of gestation (the placentation period), following short (3 h) and long (24 h) incubations. Steroid hormones influenced the expression of AQP1 and AQP5; E2 up-regulated, but P4 down-regulated mRNAs of these AQPs, whereas the protein level of studied AQPs was increased by both steroids. OT treatment decreased AQP1 (after 24 h), but increased AQP5 (after 3 h) mRNA expression. Treatment with AA significantly reduced the AQP1 expression at the mRNA level, but stimulated at the protein level. The expression of AQP5 mRNA and protein was stimulated by AA. FSK markedly decreased AQP1 mRNA, but increased of AQP5 after 3-h incubation. In turn, cAMP stimulated and inhibited transcription of AQP5 after 3- and 24-h incubations, respectively. Immunohistochemical analysis confirmed the uterine localization of AQP1 in the apical and basal membranes of endothelial cells and AQP5 in the apical membranes of epithelial cells under control condition. Treatments with P4, E2, AA, cAMP or FSK have caused additional appearance of AQP5 labeling in the basolateral membranes of epithelial cells. These results suggest a participation of steroid hormones (P4 and E2), AA derivatives and cAMP in controlling the expression of AQP1 and AQP5 as well as the distribution of AQP5 in the uterine tissue of pregnant gilts during placentation (Days 30 - 32 of gestation).

G: Fracture energy, friction and dissipation in earthquakes

Recent estimates of fracture energy G^' in earthquakes show a power-law dependence with slip u which can be summarized as G^' ∝ u^a where a is a positive real slightly larger than one. For cracks with sliding friction, fracture energy can be equated to G_f : the post-failure integral of the dynamic weakening curve. If the dominant dissipative process in earthquakes is friction, G^' and G_f should be comparable and show a similar scaling with slip. We test this hypothesis by analyzing experiments performed on various cohesive and non-cohesive rock types, under wet and dry conditions, with imposed deformation typical of seismic slip (normal stress of tens of MPa, target slip velocity > 1 m/s and fast accelerations ≈ 6.5 m/s²). The resulting fracture energy G_f is similar to the seismological estimates, with G_f and G^' being comparable over most of the slip range. However, G_f appears to saturate after several meters of slip, while in most of the reported earthquake sequences, G^' appears to increase further and surpasses G_f at large magnitudes. We analyze several possible causes of such discrepancy, in particular, additional off-fault damage in large natural earthquakes.

Expression of aquaporin 1 and 5 and their regulation by ovarian hormones, arachidonic acid, forskolin and cAMP during implantation in pigs

Aquaporin proteins (AQPs) are a family of channels expressed in numerous mammalian tissues, where they play a fundamental role in regulating water transport across cell membranes. Based on reports that AQPs are present in the reproductive system and participate in reproductive processes, our aim was to investigate the effect of progesterone (P(4)), estradiol (E(2)), oxytocin (OT), arachidonic acid (AA), forskolin (FSK) and cyclic adenosine monophosphate (cAMP) on AQP1 and AQP5 expression at mRNA and protein levels in porcine uterine explants from Days 14-16 of gestation in order to determine if they play a role in implantation period in pigs. Quantitative real time PCR and Western-blot analysis revealed that the uterine explants treated with FSK and cAMP produce delayed, but long-term effects on AQP1 abundance (24 h) while AQP5 had a rapid and sustained response to FSK and cAMP in protein content (3 and 24 h). AA increases gene and protein content of AQP1 after longer exposition whereas AQP5 increases after 3 h only at the protein level. Both AQPs potentially remains under control of steroid hormones. OT has been shown to increase AQP1, and decrease AQP5 mRNA, without visible changes in protein content. P(4), E(2), AA, FSK and cAMP caused the appearance of AQP5 expression in the basolateral plasma membrane of the epithelial cells. The staining represents most likely AQP5 functioning mechanism for both absorption and reabsorption across the glandular epithelium.

Discovery of AZD8165 – a clinical candidate from a novel series of neutral thrombin inhibitors

A novel series of neutral thrombin inhibitors has been developed using a selection process based on docking experiments and property calculations and predictions.

The use of paracetamol (acetaminophen) among a community sample of people with chronic non-cancer pain prescribed opioids

BACKGROUND

The regular use of simple analgesics in addition to opioids such as paracetamol (or acetaminophen) is recommended for persistent pain to enhance analgesia. Few studies have examined the frequency and doses of paracetamol among people with chronic non-cancer pain including use above the recommended maximum daily dose.

AIMS

To assess (i) the prevalence of paracetamol use among people with chronic non-cancer pain prescribed opioids, (ii) assess the prevalence of paracetamol use above the recommended maximum daily dose and (iii) assess correlates of people who used paracetamol above the recommended maximum daily dose including: age, gender, income, education, pain severity and interference, use of paracetamol/opioid combination analgesics, total opioid dose, depression, anxiety, pain self-efficacy or comorbid substance use, among people prescribed opioids for chronic non-cancer pain.

METHODS

This study draws on baseline data collected for the Pain and Opioids IN Treatment (POINT) study and utilises data from 962 interviews and medication diaries. The POINT study is national prospective cohort of people with chronic non-cancer pain prescribed opioids. Participants were recruited from randomly selected pharmacies across Australia.

RESULTS

Sixty-three per cent of the participants had used paracetamol in the past week (95% CI = 59.7-65.8). Among the paracetamol users 22% (95% CI = 19.3-24.6) had used paracetamol/opioid combination analgesics and 4.8% (95% CI = 3.6-6.3) had used paracetamol above the recommended maximum daily dose (i.e. > 4000 mg/day). Following binomial logistic regression (χ(2) = 25.98, df = 10, p = 0.004), people who had taken above the recommended maximum daily dose were less likely to have low income (AOR = 0.52, 95% CI = 0.27-0.99), more likely to use paracetamol/opioid combination analgesics (AOR = 2.01, 95% CI = 1.02-3.98) and more likely to take a higher opioid dose (AOR = 1.00, 95% CI = 1.00-1.01).

CONCLUSION

The majority of people with chronic non-cancer pain prescribed opioids report using paracetamol appropriately. High income, use of paracetamol/opioid combination analgesics and higher opioid dose were independently associated with paracetamol use above the recommended maximum daily dose.