Ricardo A. Cruciani

Magainin 2, a natural antibiotic from frog skin, forms ion channels in lipid bilayer membranes

We have examined the ion channel forming properties of magainin 2 by incorporating the peptide into artificial lipid bilayers held under voltage clamp. Magainin 2 increased lipid bilayer conductance in a concentration dependent manner with a Hill coefficient of 1.7. The magainin 2 conductance was selective for monovalent cations over anions with a ratio of 5:1 and had both voltage-sensitive and -insensitive components. Two structurally related but antibiotically less potent analogues, magainin 1 and Z-12, also increased lipid bilayer conductance with a similar ion selectivity but these peptides were less potent than magainin 2. We propose that the weak cation selectivity of the magainin channels can be accounted for by the inclusion of negatively charged lipids in the channel complex and suggest two possible structures for such a channel. The ionophoric properties of these peptides are likely to be proximal to their antibiotic activities.

Pain management by primary care physicians, pain physicians, chiropractors, and acupuncturists: a national survey.

Objectives: Chronic pain is a serious public health problem and is treated by diverse health care providers. In order to enhance policies and programs to improve pain care, we collected information about the distribution of pain patients among four major groups of pain management providers: primary care physicians (PCPs), pain physicians, chiropractors, and acupuncturists, and the variation in the attitudes and practices of these providers with respect to some common strategies used for pain. Methods: National mail survey of PCPs, pain physicians, chiropractors, and acupuncturists (ntotal = 3,000). Results: Eight hundred seventeen responses were usable (response rate, 29%). Analyses weighted to obtain nationally representative data showed that PCPs treat approximately 52% of chronic pain patients, pain physicians treat 2%, chiropractors treat 40%, and acupuncturists treat 7%. Of the chronic pain patients seen for evaluation, the percentages subsequently treated on an ongoing basis range from 51% (PCPs) to 63% (pain physicians). Pain physicians prescribe long-acting opioids such as methadone, antidepressants or anti-convulsants, and other nontraditional analgesics approximately 50–100% more often than PCPs. Twenty-nine percent of PCPs and 16% of pain physicians reported prescribing opioids less often than they deem appropriate because of regulatory oversight concerns. Of the four groups, PCPs are least likely to feel confident in their ability to manage musculoskeletal pain and neuropathic pain, and are least likely to favor mandatory pain education for all PCPs. Conclusions: There is substantial variation in attitudes and practices of the various disciplines that treat chronic pain. This information may be useful in interpreting differences in patient access to pain care, planning studies to clarify patient outcomes in relation to different providers and treatment strategies, and designing a system that matches chronic pain patients to appropriate practitioners and treatments.

L-Carnitine Supplementation for the Management of Fatigue in Patients With Cancer: An Eastern Cooperative Oncology Group Phase III, Randomized, Double-Blind, Placebo-Controlled Trial

PURPOSE L-carnitine, a popular complementary and alternative medicine product, is used by patients with cancer for the treatment of fatigue, the most commonly reported symptom in this patient population. The purpose of this study was to determine the efficacy of L-carnitine supplementation as a treatment for fatigue in patients with cancer. PATIENTS AND METHODS In this double-blind, placebo-controlled trial, patients with invasive malignancies and fatigue were randomly assigned to either 2 g/d of L-carnitine oral supplementation or matching placebo. The primary end point was the change in average daily fatigue from baseline to week 4 using the Brief Fatigue Inventory (BFI). RESULTS Three hundred seventy-six patients were randomly assigned to treatment with L-carnitine supplementation or placebo. L-carnitine supplementation resulted in significant carnitine plasma level increase by week 4. The primary outcome, fatigue, measured using the BFI, improved in both arms compared with baseline (L-carnitine: -0.96, 95% CI, -1.32 to -0.60; placebo: -1.11, 95% CI -1.44 to -0.78). There were no statistically significant differences between arms (P = .57). Secondary outcomes, including fatigue measured by the Functional Assessment of Chronic Illness Therapy-Fatigue instrument, depression, and pain, did not show significant difference between arms. A separate analysis of patients who were carnitine-deficient at baseline did not show statistically significant improvement in fatigue or other outcomes after L-carnitine supplementation. CONCLUSION Four weeks of 2 g of L-carnitine supplementation did not improve fatigue in patients with invasive malignancies and good performance status.

MU1: A very high affinity subtype of enkephalin binding sites in rat brain

Displacement studies of [3H]-[D-Ala2-MePhe4-Gly-ol5]-enkephalin ([3H]-DAGO) and [3H]-[D-Ala2-D-Leu5]-enkephalin ([3H]-DADL) by the corresponding unlabeled ligands show that there are at least three classes of sites which bind these enkephalin analogs with high affinity. Using computer modeling, the introduction of the third site significantly improved the goodness of fit in ten consecutive experiments. These sites appear to correspond to the mu, delta and mu 1 sites, with mean dissociation constants of 11, 1.3 and 0.9 nM for DADL and 2.5, 300 and 0.3 nM for DAGO, respectively.

Spontaneous polymerization of the antibiotic peptide magainin 2

We describe here the ability of the magainin 2 peptide to assemble spontaneously into characteristic 13‐nm diameter filaments having a 30 nm periodic helical substructure. Optimal conditions for extensive polymerization into filaments of several hundred microns required low pH and high ionic strength. Polymerization of the magainin 2 peptide may be involved in its recently described in vitro membrane‐disrupting and antibiotic activities.

Increased affinity and selectivity of enkephalin tripeptide (Tyr-D-Ala-Gly) dimers

The binding of alkylendiamide dimers of the three N-terminal residues of [D-Ala2,D-Leu5]enkephalin (DADL) to rat brain and Ng108-15 neuroblastoma-glioma cell membranes was compared with that of DADL, Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO) and morphiceptin. Tritiated DADL and DAGO were used as labeled ligands for delta- and mu-receptors, respectively. Dimerization of the tripeptides resulted in dramatic increases in both mu and delta binding. The binding to mu-receptors showed two peaks at an alkyl chain length of n = 2 and approximately n = 16. In contrast, delta binding (NG108-15 cells) increased steadily with increasing chain length. The dimers with n less than 18 were mu-preferential, and the one with n = 2 showed the most dramatic increase in mu selectivity with a 400 fold higher affinity to mu- than to delta-receptors. For long-chain alkyl spacers the compounds became delta selective.

Transcranial direct current stimulation (tDCS) relieved itching in a patient with chronic neuropathic pain.

Abstract:Itching is often called the second modality of nociception besides pain, and affects many chronic pain patients. Objectives:This case report presents a first note on beneficial effects of transcranial direct current stimulation (tDCS) on itching associated with chronic neuropathic pain in a patient diagnosed with syringomyelia. Methods:tDCS is a novel noninvasive neuromodulatory method with promising therapeutic potential in pain and symptom management. The primary mechanism of tDCS is subthreshold modulation of the neuronal resting membrane potential that induces a polarity-dependent modification of N-Methyl-D-aspartate receptor function that plays a role in neuroplasticity. The patient, a 46-year-old white male diagnosed with syringomyelia 2 decades ago, continuously reported weakness in the arms and dyesthesias including pain and itch that fluctuated in severity. Pharmacological treatment with baclofen, duloxetine, and bupropion was partially helpful; however, did not prevent flares of pain and other dysesthesias, including itch. The patient underwent 3 tDCS treatment courses consisting of 20 minutes of tDCS on 5 consecutive days at each course over 13 months. Results:Although there was no change in pain intensity or quality during or after tDCS, the treatment resulted in a reduction in itch to a mild, tolerable intensity that persisted for 3 to 4 months after each course, before returning to the pretreatment level. The patient has agreed to a plan of care that will incorporate neurostimulation every 4 to 6 months, as long as its effectiveness continues. Discussion:This case provides a rationale for future studies of neuromodulatory treatments for itch, and indicates a potential clinical use of neuromodulation in patients with unrelieved itching.

Computer modeling of subtypes of κ opioid receptors in adrenal medulla

Abstract The existence of multiple subtypes of κ opioid receptors in brain and adrenal medulla, has been controversial. We have characterized opioid receptors in frozen membranes from bovine adrenal medulla by use of objective mathematical modeling. [ 3 H]Etorphine, [ 3 H]ethylketocyclazocine (EKC) and [ 3 H][D-Ala 2 , D-Leu 5 ]enkephalin (DADL) were utilized as labeled ligands. Self- and cross-displacement curves were constructed using the three corresponding unlabeled ligands in the presence or absence of increasing concentrations of DADL. Results indicated: (1) each of the three ligands studied individually showed the presence of heterogeneity of binding sites; (2) sites labeled by etorphine were heterogeneous: 84% of etorphine binding was displaceable by 10 −4 M DADL, while the remaining 16% was DADL non-suppressible; (3) 75% of the binding of EKC was displaceable by DADL while 25% was non-suppressible; (4) mathematical modeling showed the presence of three subtypes of κ binding sites (a) κ 1 , showing slight selectivity for EKC relative to etorphine; (b) κ 2 , with K d ≈ 1 nM for etorphine, and sufficiently high affinity for DADL (K d ≈ 150 nM) so that it is suppressible by 100 μM DADL; and (c) K 3 , with no measurable affinity for DADL and a 27-fold selectivity for etorphine relative to EKC. The three subtypes of κ sites were present at concentrations of 7.4, 75, and 55 fmol/mg protein, respectively. The relative affinities of a series of κ agonists for the etorphine-binding sites were characterized. The present studies confirm the existence of three subtypes of κ opioid receptors in bovine adrenal medulla, and indicate the utility of mathematical modeling for characterization of complex receptor systems.

New methods for characterization of complex receptor systems involving 3 or more binding sites: application to brain opiate receptors.

The problems of evaluating results based on the analysis of complex binding models are considered and new methods are proposed to provide independent confirmation of the existence of multiple sites. A new plotting format for the results from experiments involving two ligands is introduced, and its utility is demonstrated for a) finding initial estimates for nonlinear least squares curve fitting; b) presenting the results of multiple experiments; and c) giving a new means for evaluating the significance of a third site. The general problem of finding initial estimates for models involving three classes of sites, and strategies for using nonlinear least squares curve fitting algorithms to optimize the fit are considered.

Handbook of methadone prescribing and buprenorphine therapy

Foreward Russell K. Portenoy MD Preface Ricardo A. Cruciani, MD, PhD & Helena Knotkova, PhD * Prescribing Methadone Safely Eliezer Soto MD, Joy Hao MD, PhD, Helena Knotkova PhD, Ricardo A. Cruciani MD, PhD * Use of Methadone in Opioid Maintenance Treatment Dr. Randy M. Seewald, MBBS * Treating Pain in Patients Receiving Methadone Maintenance for Opioid Dependence Daniel P. Alford, MD, MPH, Declan T. Barry, PhD, & David A. Fiellin, MD * Methadone Side Effects: Constipation, Respiratory Depression, Sedation, Sleep-Disordered Breathing, and the Endocrine System Lynn R. Webster, MD * Cardiovascular Effects of Methadone Miguel A. Leal, MD & Craig T. January, MD, PhD * Methadone Pharmacodynamics and Pharmacokinetics Gavin Bart, MD & Sharon L. Walsh PhD * Methadone and opioid rotation Helena Knotkova PhD, Ricardo A. Cruciani,MD, PhD, Perry G. Fine MD * Intravenous use of Methadone: efficacy and safety Sebastiano Mercadante, MD * Methadone Hyperalgesia Peggy Compton, RN, PhD, FAAN * Buprenorphine Analgesia in Chronic Pain Guy Hans, MD, PhD * Buprenorphine in Maintenance Therapy Karran A. Phillips, MD, MSc & Kenzie L. Preston, PhD * Buprenorphine Pharmacodynamics and Pharmacokinetics Sharon L. Walsh, PhD & Lisa S. Middleton, PhD 13. Buprenorphine metabolism and drug-drug interactions Robert Taylor Jr., PhD, Robert B. Raffa, PhD, & Joseph V. Pergolizzi Jr., MD * Buprenorphine: side effects and tolerability Tabitha Washington, MD, MS & Gilbert J. Fanciullo, MD, MS * Buprenorphine and Opioid Rotation Douglas L. Gourlay, MD, MSc, FRCP, FASAM & Howard A. Heit MD, FACP, FASAM * Methadone and buprenorphine use during the perinatal period Alice Ordean MD, CCFP, MHSc * Methadone and Buprenorphine Prescribing in the Palliative Care Population Shalini Dalal MD & Eduardo Bruera MD * Methadone Prescribing In The Sickle Cell Patient Wally R. Smith, MD & Abdulkhaliq J. Alsalman, MS * Methadone and Buprenorphine Analgesia in Older Patients David Lussier, MD, FRCP(c)