Anti-nociception mediated by a κ opioid receptor agonist is blocked by a δ receptor agonist.

BACKGROUND AND PURPOSE: The opioid receptor family comprises four structurally homologous but functionally distinct sub-groups, the µ (MOP), δ (DOP), κ (KOP) and nociceptin (NOP) receptors. As most opioid agonists are selective but not specific, a broad spectrum of behaviours due to activation of different opioid receptors is expected. In this study, we examine whether other opioid receptor systems influenced KOP-mediated antinociception. EXPERIMENTAL APPROACH: We used a tail withdrawal assay in C57Bl/6 mice to assay the antinociceptive effect of systemically administered opioid agonists with varying selectivity at KOP receptors. Pharmacological and genetic approaches were used to analyse the interactions of the other opioid receptors in modulating KOP-mediated antinociception. KEY RESULTS: Etorphine, a potent agonist at all four opioid receptors, was not anti-nociceptive in MOP knockout (KO) mice, although etorphine is an efficacious KOP receptor agonist and specific KOP receptor agonists remain analgesic in MOP KO mice. As KOP receptor agonists are aversive, we considered KOP-mediated antinociception might be a form of stress-induced analgesia that is blocked by the anxiolytic effects of DOP receptor agonists. In support of this hypothesis, pretreatment with the DOP antagonist, naltrindole (10 mg·kg(-1) ), unmasked etorphine (3 mg·kg(-1) ) antinociception in MOP KO mice. Further, in wild-type mice, KOP-mediated antinociception by systemic U50,488H (10 mg·kg(-1) ) was blocked by pretreatment with the DOP agonist SNC80 (5 mg·kg(-1) ) and diazepam (1 mg·kg(-1) ). CONCLUSIONS AND IMPLICATIONS: Systemic DOP receptor agonists blocked systemic KOP antinociception, and these results identify DOP receptor agonists as potential agents for reversing stress-driven addictive and depressive behaviours mediated through KOP receptor activation. LINKED ARTICLES: This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.

Renal autotransplantation as savior in hybrid surgery for aortic aneurysm repair.

Renal autotransplantation is a safe and effective procedure to reconstruct the urinary tract. The current indications for autotransplantation include renal vascular disease, severe ureteral damage, tumours of the kidney and ureter, complex nephrolithiasis and retroperitoneal fibrosis. We report a rare case where we had to perform renal autotransplantation along with hybrid surgery for aortic aneurysm repair. To our knowledge, this is the first case report of its kind for this specific condition.

Chronic morphine administration results in tolerance to delta opioid receptor-mediated antinociception.

Delta opioid receptor agonists produce only a moderate degree of antinociception, possibly reflecting the predominantly intracellular location of delta opioid receptor. However, recent studies suggest that short term morphine pretreatment can increase delta opioid receptor-mediated antinociception by promoting the translocation of delta opioid receptor to the cell surface. Even more striking sensitization has been reported after long term morphine pretreatment and withdrawal in locomotor tests. In the present study we therefore examined the effects of longer term morphine pretreatment and withdrawal on delta opioid receptor-mediated antinociception in the formalin test. Male adult rats were pretreated daily with morphine (10 mg/kg s.c.) or saline for 10 days, and were tested acutely with the delta opioid receptor agonist [D-Ala2,Glu4]-deltorphin (intrathecal) at 0, 7 and 14 days of withdrawal. Unexpectedly, chronic morphine pre-exposure resulted in tolerance to [D-Ala2,Glu4]-deltorphin-induced antinociception, and this occurred at 0 and 7 but not 14 days of morphine withdrawal. Morphine challenge at withdrawal day 7 confirmed the presence of tolerance to the antinociceptive effects of this drug. Chronic morphine pretreatment also resulted in tolerance to the locomotor stimulant effect of [D-Ala2,Glu4]-deltorphin (given i.c.v.), contrary to a previous report of sensitization. However, consistent with previous reports, short term (2 day) pretreatment with morphine did result in sensitization to [D-Ala2,Glu4]-deltorphin. Subsequent in vitro analysis, using [125I][D-Ala2,Glu4]-deltorphin or guanosine 5'(gamma-35S-thio) triphosphate autoradiography, did not reveal any changes in delta opioid receptor binding or function resulting from chronic morphine pretreatment. In conclusion, chronic morphine pretreatment caused tolerance to delta opioid receptor-mediated behavioral effects with no clear change at the receptor level.

Enhanced calcium signaling to bradykinin in airway smooth muscle from hyperresponsive inbred rats.

Inbred Fischer 344 rats display airway hyperresponsiveness (AHR) in vivo compared with the normoresponsive Lewis strain. Fischer AHR has been linked with increased airway smooth muscle (ASM) contraction ex vivo and enhanced ASM cell intracellular Ca(2+) mobilization in response to serotonin compared with Lewis. To determine the generality of this association, we tested whether bradykinin (BK) also stimulates greater contraction of Fischer airways and greater Ca(2+) mobilization in Fischer ASM cells. Explants of Fischer intraparenchymal airways constricted faster and to a greater degree in response to BK than Lewis airways. BK also evoked higher Ca(2+) transients in Fischer than in Lewis ASM cells. ASM cell B(2) receptor expression was similar between the two strains. BK activated both phosphatidylinositide-specific phospholipase C (PI-PLC) and phosphatidylcholine-specific PLC to mobilize Ca(2+) in Fischer and Lewis ASM cells. PI-PLC activity, as measured by inositol polyphosphate accumulation, was similar in the two strains. PKC inhibition with GF109203X, Go6973, or Go6983 attenuated BK-mediated Ca(2+) transients in Fischer cells, whereas GF109203X potentiated while Go6976 and Go6983 did not affect Ca(2+) transients in Lewis cells. Enhanced Ca(2+) mobilization in ASM cells can arise from variations in PKC and may be an important component of nonspecific, innate AHR.

Endopyelotomy - a Minimally Invasive Surgical Option for Pelvi-ureteric Junction Obstruction: a Study Of 34 Cases.

We performed antegrade endopyelotomy in 34 cases in the last 2½ years. In all cases standardized antegrade percutaneous method was used. A single guide wire and a cold knife were used to perform the endopyelotomy. Nephrostomy tube was retained for 48 hours and the repair stented for 6 weeks. Patients were followed up at 3 months, 6 months and 1 year post-operatively for subjective improvement and objectively by DTPA scans/IVU and ultrasound. The population included 2 bilateral cases, one horseshoe kidney and 3 children. The patient's age ranged from 9-59 years, average 32 years. There were 21 males and 13 females. 28 renal units were primary and 8 were secondary pelviureteric junction (PUJ) obstruction. Follow up period was 3-28 months. Most cases had significant symptomatic and functional recovery postoperatively. Five cases presented with urinary tract infection, which regressed after treatment. At 3(rd) month postoperatively the DTPA/IVU scan was equivocal in 7 cases. In these, a RGP was done which in every case showed a patent PUJ. In 5 cases that were still symptomatic, 6-8 weeks of further stenting produced symptom regression. Two cases failed and needed revision, one by open pyeloplasty and the other by endopyelotomy. Our success rate overall in these cases followed upto 1 year post operatively is 91.6%. We conclude that endopyelotomy is successful across a wide spectrum of cases.

Warfarin use in atrial fibrillation: A random sample survey of family physician beliefs and preferences.

BACKGROUND: In clinical practice, warfarin is underused for the prevention of stroke in individuals with atrial fibrillation despite unequivocal evidence of benefit and acceptable safety. OBJECTIVE: To ascertain, from primary care physicians, their beliefs and preferences regarding the use of warfarin in patients with atrial fibrillation. MATERIALS AND METHODS: A questionnaire was mailed to a random sample of 1000 primary care physicians in Ontario. Physician prescribing preferences from among treatment options available (warfarin, acetylsalicylic acid, ticlopidine, no therapy and other) were recorded for four separate scenarios of atrial fibrillation with varying degrees of risk for stroke. Physician perception of the risks associated with warfarin use and their awareness of the evidence of benefit were assessed. RESULTS: Three hundred twenty-four physicians returned completed questionnaires. Among the four scenarios, physicians choosing not to use warfarin were three to six times more likely than physicians choosing to use warfarin to believe that there was inadequate evidence of benefit of warfarin for stroke prophylaxis, and they were four to six times more likely to be concerned about the risks of hemorrhage. These beliefs did not change significantly with scenarios describing patients with a high risk of stroke. CONCLUSIONS: Physician reluctance to use warfarin is associated with a false understanding of the benefit to risk ratio, which arises from a low appreciation of therapeutic benefits and a high concern regarding hemorrhage.

Supraspinal antinociceptive response to [D-Pen(2,5)]-enkephalin (DPDPE) is pharmacologically distinct from that to other delta-agonists in the rat.

The cloned delta-opioid receptor (DOR) is being investigated as a potential target for novel analgesics with an improved safety profile over mu-opioid receptor agonists such as morphine. The current study used antisense techniques to evaluate the role of DOR in mediating supraspinal antinociception in rats. All of the opioid agonists tested (delta-selective: deltorphin II, DPDPE, pCl-DPDPE, SNC80; mu-selective: DAMGO; i.c.v.) provided significant, dose-dependent antinociception in the paw pressure assay. Administration of a phosphodiester antisense oligonucleotide (i.c.v. ) targeted against DOR inhibited antinociception in response to SNC80, deltorphin II, and pCl-DPDPE compared with mismatch and saline-treated controls. However, antisense treatment did not inhibit the response to DPDPE or DAMGO. In contrast, the highly selective mu-antagonist CTOP blocked antinociception in response to ED(80) concentrations of DAMGO and DPDPE, reduced the response to pCl-DPDPE, and did not alter the response to deltorphin II or SNC80. In total, these data suggest that DOR mediates the antinociceptive response to deltorphin II, SNC80, and pCl-DPDPE at supraspinal sites and further demonstrates that the DOR-mediated response to deltorphin II and SNC80 is independent of mu-receptor activation. Conversely, supraspinal antinociception in response to DPDPE is mediated by a receptor distinct from DOR; this response is directly or indirectly sensitive to mu-receptor blockade. The distinct pharmacological profile of DPDPE suggests that either this prototypical delta-agonist mediates antinociception by a direct, nonselective interaction at mu-receptors or DPDPE interacts with a novel delta-subtype that, in turn, indirectly activates mu-receptors in the brain.

Stability of catalase and its potential role in lipid oxidation in meat.

The activity of catalase in microbial growth-controlled and uncontrolled ground beef muscle (semimembranosus, SM) did not change (P>0.05) during 6-day storage at 4°C. Likewise, catalase activity in ground, beef SM and longissimus dorsi (LD), pork LD, and chicken breast (B) and thigh (T) muscles was not affected (P>0.05) by 2-month storage at -20°C, with or without mid-month thawing/refreezing. When sodium azide (a catalase inhibitor) was added to ground beef SM, lipid oxidation (as measured by peroxide values) during 4-day refrigeration was higher (P<0.05) in treated samples - 43 and 55% higher at day 2 and day 4, respectively - than in the controls. It was concluded that catalase would be stable during meat storage/distribution and contribute significantly to the antioxidative process in raw meat products.

Mechanisms of the potentiation by adenosine of adenosine triphosphate-induced calcium release in tracheal smooth-muscle cells.

The effects of concomitant P1-receptor stimulation on peak intracellular Ca2+ release by extracellular adenosine 5'-triphosphate (ATP) and 5-hydroxytryptamine (5-HT) were investigated in cultured airway smooth-muscle (ASM) cells. The results show that peak Ca2+ release to ATP is enhanced by preincubation with adenosine (ADO) and with the specific A3 receptor agonist 1-Deoxy-1-(6-([(3-iodophenyl)methyl] amino)-9H-purin-9-yl)-N-methyl-beta-D-ribofuranuronamide (1B-MECA). The response to 5-HT, a smooth-muscle contractile agonist, was also enhanced after preincubation with ADO. Further measurements showed that this enhancement of the response to ATP was dependent on extracellular calcium because it was abolished by the removal of Ca2+ from the extracellular fluid and by incubation with the calcium channel blocker nifedipine. In addition, there was no difference between the levels of total inositol phosphates measured in the presence of ATP alone or of ADO + ATP. AACOCF3, a specific blocker of phospholipase A2, decreased the peak Ca2+ response to ATP and abolished the enhanced response to ATP and 5-HT produced by ADO. We conclude that stimulation of P1 and P2 receptors in ASM cells activates not only phospholipase C but also phospholipase A2. The enhancement of ATP-induced and 5-HT-induced Ca2+ release is due to Ca2+ influx from the extracellular fluid through a Ca2+ channel presumably modulated by arachidonic acid. These data show that endogenous ADO may modulate airway hyperresponsiveness by enhancing the ASM response to contractile agonists.

Colorectal screening patterns and perceptions of risk among African-American users of a community health center.

This study investigated risk perceptions and screening patterns for colorectal cancer among predominately low-income African-Americans age 50 and older who used a community health center. The majority of respondents either rated their risk as below average (36%) or did not know their risk (37%) for colorectal cancer. Individuals who provided a risk estimate versus those who did not know their risk were younger and held more accurate beliefs about colorectal cancer. Attributions of perceived risk best distinguished respondents who evaluated their risk to be below average versus average and above average. Compared to respondents who could not explain their risk, those who provided psychological, personal action, and heredity causes were more likely to view their risk as below average than average or above average. In comparison to national norms, these subjects reported higher frequencies of ever having had a digital rectal exam (DRE, 90%), fecal occult blood test (FOBT, 75%) and sigmoidoscopy (SIG, 33%). Moreover, 63%, 53%, and 81% reported their most recent screening for DRE, FOBT, and SIG, respectively, in accordance with ACS and NCI recommended guidelines. However, a subsequent medical audit failed to confirm these self-reports. These results suggest that: 1) educational efforts are needed to enhance knowledge and accuracy of risk perceptions for colorectal cancer; 2) further studies on attributions of risk are needed that may prove useful for developing intervention programs, and 3) studies need to interpret self-report data for colorectal cancer with caution.

Microbial biosorption of copper and lead from aqueous systems.

Biosorption of metal ions from aqueous systems was evaluated using a culture of acidic soil isolates grown in a completely mixed, aerobic, semi-batch culture reactor. The laboratory scale system was used to test single and bimetallic solutions of copper and lead with sulfates, chlorides, or nitrates. To elucidate the key factors influencing biosorption and to characterize metal uptake by cellular and extra cellular components of the microbial system, a dialysis testing procedure was developed. A direct contact technique was used to determine the rate of metal sorption on cellular surfaces. The effectiveness of biosorption was influenced by pH, initial metal concentrations, and anionic composition. Respirometric tests were carried out to identify potential inhibitory effects of metal accumulation on microbial oxygen uptake rates.