In order to provide new insight into the determining factors of membrane-bound peptide conformation which might play an important role in peptide-receptor docking and further biological behaviors, the dodecylphosphocholine (DPC) micelle-bound conformations of bifunctional peptide derivatives of δ-preferring opioid agonists and NK1 antagonists (1: Tyr-D-Ala-Gly-Phe-Met-Pro-Leu-Trp-O-3,5-Bzl(CF3)2; 2: Tyr-D-Ala-Gly-Phe-Met-Pro-Leu-Trp-NH-3,5-Bzl(CF3)2; 3: Tyr-D-Ala-Gly-Phe-Met-Pro-Leu-Trp-NH-Bzl) were determined based on 2D NMR studies. Although the differences in the primary sequence were limited to the C-terminus, the obtained NMR conformations were unexpectedly different for each compound. Moreover, their biological activities showed different trends in direct relation to the compound-specific conformations in DPC micelles. The important result is that not only were the NK1 antagonist activities different (the pharmacophore located at the C-terminus), but the opioid agonist activities (this pharmacophore was at the structurally preserved N-terminus) also were shifted, suggesting that a general conformational change in the bioactive state was induced due to relatively small and limited structural modifications.

We have developed a highly effective method for in vivo gene silencing in the spinal cord and dorsal root ganglia (DRG) by a cationic lipid facilitated delivery of synthetic, small interfering RNA (siRNA). A siRNA to the delta opioid receptor (DOR), or a mismatch RNA, was mixed with the transfection reagent, i-Fect™ (vehicle), and delivered as repeated daily bolus doses (0.5 μg to 4 μg) via implanted intrathecal catheter to the lumbar spinal cord of rats. Twenty-four hours after the last injection, rats were tested for antinociception by the DOR selective agonist, [D-Ala2, Glu4]deltorphin II (DELT), or the mu opioid receptor (MOR) selective agonist, [D-Ala2, N-Me-Phe4, Gly-ol5]enkephalin (DAMGO). Pretreatment with the siRNA, but not the mismatch RNA or vehicle alone, blocked DELT antinociception dose-dependently. The latter was concomitant with a reduction in the spinal immunoreactivity and receptor density of DOR, and in DOR transcripts in the lumbar DRG and spinal dorsal horn. Neither siRNA nor mismatch RNA pretreatment altered spinal immunoreactivity of MOR or antinociception by spinal DAMGO, and had no effect on the baseline thermal nociceptive threshold. The inhibition of function and expression of DOR by siRNA was reversed by 72 hr after the last RNA injection. The uptake of fluorescence-tagged siRNA was detected in both DRG and spinal cord. The low effective dose of siRNA/i-Fect™ complex reflects an efficient delivery of the siRNA to peripheral and spinal neurons, produced no behavioral signs of toxicity. This delivery method may be optimized for other gene targets.

A series of bifunctional peptides that act as agonists for δ and μ opioid receptors with δ selectivity and as antagonist for neurokinin-1 (NK1) receptors were designed and synthesized for potential application as analgesics in various pain states. The peptides were characterized using radioligand binding assays and functional assays using cell membrane and animal tissue. Optimization was performed on the fifth residue which serves as an address moiety for both receptor recognitions. It had critical effects on both activities at δ/μ opioid receptors and NK1 receptors. Among the synthesized peptides, H-Tyr-D-Ala-Gly-Phe-Met-Pro-Leu-Trp-O-3,5-Bzl(CF 3 ) 2 (5) and H-Tyr-DAla-Gly-Phe-Nle-Pro-Leu-Trp-O-3,5-Bzl(CF 3 ) 2 (7) had excellent agonist activity for both δ opioid and μ opioid receptors and excellent antagonist activity for NK1 receptors. These results indicate that the rational design of multifunctional ligands with opioid agonist and neurokinin-1 antagonist activities can be accomplished and may provide a new tool for treatment of chronic and several pain states.

A series of bifunctional peptides with opioid agonist and substance P antagonist bioactivities were designed with the concept of overlapping pharmacophores. In this concept, the bifunctional peptides were expected to interact with each receptor separately in the spinal dorsal horn where both the opioid receptors and the NK1 receptors were found to be expressed, to show an enhanced analgesic effect, no opioid-induced tolerance, and to provide better compliance than coadministration of two drugs. Compounds were synthesized using a two-step combinatorial method for C-terminal modification. In the method, the protected C-terminal-free carboxyl peptide, Boc-Tyr( tBu)- d-Ala-Gly Phe-Pro-Leu-Trp(Boc)-OH, was synthesized as a shared intermediate using Fmoc solid phase chemistry on a 2-chlorotrityl resin. This intermediate was esterified or amidated in solution phase. The structure-activity relationships (SAR) showed that the C-terminus acted as not only a critical pharmacophore for the substance P antagonist activities, but as an address region for the opioid agonist pharmacophore that is structurally distant from the C-terminal. Among the peptides, H-Tyr- d -Ala-Gly-Phe-Pro-Leu-Trp-NH-Bzl ( 3) demonstrated high binding affinities at both delta and mu receptors ( K i = 10 and 0.65 nM, respectively) with efficient agonist functional activity in the mouse isolated vas deferens (MVD) and guinea pig isolated ileum (GPI) assays (IC 50 = 50 and 13 nM, respectively). Compound 3 also showed a good antagonist activity in the GPI assay with substance P stimulation ( K e = 26 nM) and good affinity for the hNK1 receptor ( K i = 14 nM). Consequently, compound 3 is expected to be a promising and novel type of analgesic with bifunctional activities.

BackgroundTo investigate the injury pattern, severity, and mortality of elderly patients hospitalized for treatment of trauma following fall accidents.MethodsData obtained from the Trauma Registry System were retrospectively reviewed for trauma admissions between January 1, 2009 and December 31, 2013 in a Level I trauma center. Of 16,548 registered patients, detailed information was retrieved from the 2,403 elderly patients (aged 65 years and above) with fall accidents and was compared with information from 1,909 adult patients (aged 20–64) with fall accidents.ResultsFalls presented the major mechanism for admission (59.9%) in the elderly patients. The number of elderly patients who fell from a height <1 m was greater than that of the adult patients (91.9% vs. 62.5%, respectively, p <0.001). The Injury Severity Score (ISS) (9.3 ± 4.4 vs. 8.3 ± 6.1, respectively, p =0.007) and New Injury Severity Score (NISS) (10.3 ± 6.8 vs. 9.5 ± 8.2, respectively, p <0.001) were significantly higher in the elderly than the adult patients. A significantly larger proportion of the elderly patients were admitted to the ICU (16.2% vs. 13.4%, respectively, p =0.009), and the elderly were found to have longer stays in the intensive care unit (ICU) (8.6 days vs. 7.6 days, respectively, p =0.034) but not in the hospital in general (9.6 days vs. 8.5 days, respectively, p =0.183). Additionally, a significantly higher percentage of the elderly patients sustained subdural hematoma (10.1% vs. 8.2%, respectively, p =0.032) and femoral fracture (50.6% vs. 14.1%, respectively, p <0.001). There were significant differences in in-hospital mortality (18.2% vs. 10.3%, respectively, p =0.031) and length of stay in the hospital (11.6 days vs. 14.9 days, respectively, p =0.037) between the elderly and adult patients with subdural hematoma, but not between those with femoral fracture.ConclusionsAnalysis of the data indicates that elderly patients hospitalized for treatment of trauma following fall accidents present with a bodily injury pattern that differs from that of adult patients and have a higher severe injury score, worse outcome, and higher mortality than those of adult patients.