Development of a novel radioiodinated dermorphin analog for mu opioid receptor studies [abstract]

Abstract only availableFaculty Mentor: Dr. John Lever, BiologyDermorphin is a naturally occurring opioid peptide that has been isolated from the skin of the frog Phylomedusa sauvagei. It has been characterized as having high affinity and selectivity for the mu opioid receptor. The goal of our study was to investigate novel analogs of dermorphin that could be radiolabeled and then evaluated as in vitro and in vivo probes for the mu opioid receptor. Our group synthesized DAPP, a novel peptide and dermorphin derivative with the amino acid sequence H-Dmt-D-Ala-Phe-Phe-NH2. It has been radiolabeled with iodine and used in various experiments to determine its receptor binding characteristics. Autoradiography studies were performed in order to define the profile of radioligand binding in mu, delta, and kappa opioid receptor types and to determine the degree of nonspecific binding and opioid receptor selectivity. Autoradiography is the detection of radioisotopes on X-ray film. For in vitro autoradiography, slide-mounted tissue sections of mouse brain were incubated with I-125 DAPP. The tissue specimen itself was the source of the radiation, and the emissions of the isotopes formed a visible image upon development. These studies indicated that I-125 DAPP exhibits high levels of binding in the frontal cortex, striatum, thalamus, and superior and inferior colliculi, and low levels in the cerebellum. The affinity of I-125 DAPP for mu opioid receptors was confirmed when labeling was not seen in the presence of a mu blocker (DAMGO); under the same conditions, I-125 DAPP was not prevented from binding by delta (DPDPE) or kappa (U69,593) blockers. Preliminary quantitative analysis of the distilled image by computerized densitometry suggests that we can achieve 80-90% specific binding with this compound. As a prelude to in vivo studies, we determined the distribution coefficient (log D) for I-125 DAPP at pH 7.4. This number is the ratio of the compound's concentration in the octanol phase to its concentration in the aqueous phase, and is an indication of the degree of lipophilicity of a compound. The log D for I-125 DAPP was determined as 2.99 ± 0.0117 (mean ± SD), using four consecutive measurements with a coefficient of variation (SD/mean x 100) of 0.39%. This relatively high value indicates a more lipophilic compound, suggesting that that I-125 DAPP will successfully cross biological membranes. An in vivo study was then conducted to determine the distribution of DAPP throughout the mouse body thirt

Elastic Abdominal Binders Reduce Cesarean Pain Postoperatively: A Randomized Controlled Pilot Trial

Introduction. A potential non-pharmacologic way to reduce postoperativepain and bleeding is using an abdominal binder duringpostoperative recovery. This study aims to determine the effect anelastic abdominal binder has on postoperative pain and hemorrhageafter cesarean delivery. Methods. A randomized, single-site, pilot trial was conducted at twoprenatal care clinics and an academic hospital in Kansas. Beginningin April 2013, 60 patients were enrolled if delivering via cesarean.Participants were randomized to receive an abdominal binder or to acontrol group (did not use binder). Pain levels were reported by questionnaireone day after surgery using a 0 to 10 scale, with 10 being theworst pain. Patient characteristics and blood loss were assessed bymedical record review. Results. Of the 56 patients completing the study, 29 (51.8%) wererandomized to the binder group and 27 (48.2%) were randomizedto the control group. The binder group reported significantly lowerpain score (p = 0.019) and average pain score (p = 0.024). There wasno difference in body mass index, age, previous surgery, infant birthweight, estimated blood loss, and average dose of pain medicationduring the first 24 hours after the cesarean delivery between the twogroups. There was no difference in pre- and post-operative hemoglobinlevels by treatment group (p = 0.406). Conclusions. Abdominal binders may be associated with improvedpostoperative pain scores but did not affect postoperative hemorrhage.Kans J Med 2018;11(2):48-53

Synthesis and binding studies of novel sigma receptor ligands

Abstract only availableSigma receptors are binding sites that are found in the brain, in the endocrine and immune systems, and also in the lungs, kidneys, intestines, muscles and especially the liver. They are classified into two subtypes, sigma1 and sigma2, both of which have unique characteristics. Sigma receptors in the central nervous system are thought to be involved in disorders such as psychoses, Alzheimer's disease, and schizophrenia. A number of human tumors also show high densities of sigma receptors. In this study, three novel compounds were synthesized with the intent of characterizing how their structural differences affect affinity for the sigma1 and sigma2 receptors. We investigated derivatives of a potent sigma1 selective agonist, 1-(3',4'-dimethoxyphenethyl)-4-(3''-phenyl propyl)piperazine, developed by Santen Pharmaceutical Co. Specifically, the 4'-methoxy moiety was replaced by benzyloxy, phenethyloxy and 3-phenylpropyloxy substituents. These were prepared by reaction of the corresponding 4'-phenol with base and treatment with phenethyl bromide, 3-phenylpropyl bromide or benzyl bromide. For the phenethyl and 3-phenylpropyl derivatives, a mixture of 40% KOH and tetrabutylammonium hydroxide (1M in MeOH) was used as the base. Column chromatography provided these target compounds in 81 - 94% purified yields. The benzyl derivative proved difficult to obtain using this procedure, and different conditions were used to synthesize this compound. The 4'-phenol was reacted with benzyl bromide and potassium carbonate in ethanol to give the benzyl ether in 35% yield after purification by column chromatography. All three compounds were characterized by 1H NMR, and were analyzed by elemental analysis and HPLC. Currently, competition receptor binding studies are being run on the synthesized compounds to measure their affinities for sigma1 and sigma2 receptors.NSF-REU/NIH Program in Radiochemistr

Tumour regression and improved gastrointestinal tolerability from controlled release of SN-38 from novel polyoxazoline-modified dendrimers

Irinotecan is used clinically for the treatment of colorectal cancer; however, its utility is limited by its narrow therapeutic index. We describe the use of a generation 5 l-lysine dendrimer that has been part-modified with a polyoxazoline as a drug delivery vehicle for improving the therapeutic index of SN-38, the active metabolite of irinotecan. By conjugating SN-38 to the dendrimer via different linker technologies we sought to vary the release rate of the drug to generate diverse pharmacokinetic profiles. Three conjugates with plasma release half-lives of 2.5 h, 21 h, and 72 h were tested for efficacy and toxicity using a mouse SW620 xenograft model. In this model, the linker with a plasma release half-life of 21 h achieved sustained SN-38 exposure in blood, above the target concentration. Control over the release rate of the drug from the linker, combined with prolonged circulation of the dendrimer, enabled administration of an efficacious dose of SN-38, achieving significant regression of the SW620 tumours. The conjugates with 2.5 and 72 h release half-lives did not achieve an anti-tumour effect. Intraperitoneal dosing of the clinically used prodrug irinotecan produces high initial and local concentrations of SN-38, which are associated with gastrointestinal toxicity. Administration of the 21 h release dendrimer conjugate did not produce a high initial Cmax of SN-38. Consequently, a marked reduction in gastrointestinal toxicity was observed relative to irinotecan treatment. Additional studies investigating the dose concentrations and dose scheduling showed that a weekly dosing schedule of 4 mg SN-38/kg was the most efficacious regimen. After 4 doses at weekly intervals, the survival period of the mice extended beyond 70 days following the final dose. These extensive studies have allowed us to identify a linker, dose and dosing regimen for SN-38 conjugated to polyoxazoline-modified dendrimer that maximised efficacy and minimised adverse side effects

Economic valuation of the potential health benefits from foods enriched with plant sterols in Canada

Background: Increased consumption of foods containing plant sterols has the potential to reduce the incidence of coronary heart disease (CHD) and thus reduce costs associated with treating that disease in a significant way. This paper reports the results of an investigation of the potential monetary benefits of allowing foods enriched with plant sterols to be marketed in Canada. Objective: The objective of this research was to estimate the annual savings that would accrue to Canada's single-payer publicly funded health care system if plant sterols were approved for use. If foods containing plant sterols are consumed at a sufficient rate, a reduction in CHD should follow. Given the significant costs associated with CHD, approval of plant sterols in Canada has important public policy implications. Design: This research employs a variation of traditional cost-of-illness analysis entailing four steps: (1) estimation of a ‘success rate’ (proportion of persons who would consume plant sterols at the necessary rate); (2) presumption of blood cholesterol reduction due to plant sterol consumption; (3) assumption of reduction in CHD that follows from blood cholesterol reduction; and (4) calculation of cost savings associated with reduced incidence of CHD. Results: Calculations were carried out for four scenarios: ideal, optimistic, pessimistic, and very pessimistic. It was estimated that between $38 million (very pessimistic scenario) and $2.45 billion (ideal scenario) could be saved annually by Canada's health care system with plant sterol-enriched food products being made available for sale. Conclusion: Significant expenditure reductions within Canada's publicly funded health care system could be realized with plant sterols approved for sale. Reduced CHD resulting from lower blood cholesterol levels would lessen the financial burden of disease in Canada

Psychometric properties of a new questionnaire to assess eating in the absence of hunger in children and adolescents

Background: Eating in the absence of hunger (EAH), studied in the context of laboratory paradigms, has been associated with obesity and is predictive of excess weight gain in children. However, no easily administered questionnaire exists to assess for EAH in children. Objective: We developed an Eating in the Absence of Hunger Questionnaire to be administered to children and adolescents (EAH-C) and examined psychometric properties of the measure. Design: Two-hundred and twenty-six obese (BMI ≥ 95th percentile for age and sex, n = 73) and non-obese (BMI \u3c 95th percentile, n = 153) youth (mean age ± S.D., 14.4 ± 2.5 y) completed the EAH-C and measures of loss of control and emotional eating, and general psychopathology. Temporal stability was assessed in a subset of participants. Results: Factor analysis generated three subscales for the EAH-C: Negative Affect, External Eating, and Fatigue/Boredom. Internal consistency for all subscales was established (Cronbach’s alphas: 0.80–0.88). The EAH-C subscales had good convergent validity with emotional eating and loss of control episodes ( p’s \u3c 0.01). Obese children reported higher Negative Affect subscale scores than non-obese children ( p ≤ 0.05). All three subscales were positively correlated with measures of general psychopathology. Intra-class correlation coefficients revealed temporal stability for all subscales (ranging from 0.65 to 0.70, p’s \u3c 0.01). We conclude that the EAH-C had internally consistent subscales with good convergent validity and temporal stability, but may have limited discriminant validity. Further investigations examining the EAH-C in relation to laboratory feeding studies are required to determine whether reported EAH is related to actual energy intake or to the development of excess weight gain