By O. Jens. Gutenberg College.
Researchers found similar amplitudes and latencies of tactile-evoked potentials purchase clonidine 0.1 mg otc, similar recovery rates of compound muscle action poten- tials, and an increase in the number of myelinated axons in the distal stumps following both nerve graft and synthetic nerve conduit repairs. This example illustrates true translational neuroscience research, beginning from a technical concept in a small laboratory to large animal research with the support of a biotechnology company, to human trials, and clinical application. However, as is the case with many FDA-approved products, additional postapproval clinical trials © 2005 by CRC Press LLC (now ongoing) will be critical to determine whether the product remains a useful clinical entity over time. Current research in nerve conduits centers on many of the same interventions attempted for spinal cord regeneration. They express specific cell adhesion molecules and bind specific extracellular matrix molecules that allow axon exten- sion; they produce and secrete neurotrophic factors for neuronal support and axonal growth; and they possess receptors for neurotrophic factors and may act as neurotro- phin-presenting cells for axon pathfinding. Some researchers are thus attempting to incorporate SCs into nerve conduits to improve the current results. Researchers are studying different types of fibrin glues, fasteners, and laser repairs for treating peripheral nerve lesions in animals. If axons fail to reach the correct sensory or motor end organ, patients will not achieve clinical improvement, and even worse, may be left with painful consequences. The rat femoral nerve that divides into a motor branch to the quadriceps and a sensory branch to the skin serves as a useful model for studying axon pathfinding. Research- ers have found that motor axons are better at finding appropriate motor fascicles in the distal stump than are sensory axons — a process called preferential motor reinnervation. Following injury, regenerating axons form many (redundant) collateral sprouts, and these enter SC tubules in the distal stump in a random fashion. Sensory axon neurons, on the other hand, do not necessarily trim back branches that have inappropriately entered motor fascicles in a distal stump. This suggests that local signals within SC tubules influence axonal pathfinding and under specific conditions can significantly increase specificity of regeneration. Other promising interventions include noninvasive measures to enhance periph- eral nerve regeneration.
While there are randomized controlled trials of these therapies for some indications cheap clonidine 0.1mg mastercard, the evidence for most neurological disorders is limited. There are other complementary therapies such as use of magnetic fields and aromatherapy that have no specific chapter focused on these treatments, but relevant data are discussed in the disease-oriented chapters. There are several modalities that are usually considered more within the realm of conventional medicine and are not discussed in any detail; these include transcranial magnetic stimulation and hyperbaric oxygen. There are groups of complementary therapies, such as energy-based therapies, for which data are limited and these also are not discussed in any detail (e. Some of the chapters include historical perspectives; these are particularly the chapters on traditional Chinese medicine and ayurveda. The utility of modalities such as acupuncture does not depend on acceptance of the historical perspectives, and some even feel that this historical perspective may be impeding its scientific development. However, it is of some importance to know these historical perspectives and to refine the explanatory concepts with empirically testable theories on the mechanisms of action. The goal for this book is to be a useful resource to conventional or complementary health-care providers who are trying to optimize the health of their patients. Acknowledgements I would like to acknowledge all the clinical researchers whose published clinical trials and insights have produced the knowledge upon which this book is based, and all the government and non-government organizations that have funded the research discussed in this book. The US National Institutes of Health National Center for Complementary and Alternative Medicine has supported the Oregon Center for Complementary and Alternative Medicine in Neurological Disorders (ORCCAMIND) ( I have appreciated the discussions I have had with all the researchers at ORCCAMIND concerning many of the topics discussed in this book. I would like to thank all the members of my research staff who have been excellent at carrying out many research projects and allowing me to focus some time on this book. I would like specifically to acknowledge Andy Fish for organizing the chapters and correspondence from both the authors and CRC Press, and Shirley Kishiyama who helped with editing and graphics. DEDICATION To my family, for their love and support Color plates Plate 1 Regional cerebral blood flow changes in pain-related activity within primary somatosensory cortex (S1) and anterior cingulate cortex (ACC) associated with hypnotic suggestions for increased pain (↑), decreased pain (↓) and increased minus decreased- pain (↑–↓) intensity (Int), and unpleasantness (Unp) during the sensory-modulation experiment (from reference 54) and the affective- modulation experiment (from reference 53). Modulatory effects of suggestions for ↑ and ↓ pain (Int or Unp) are revealed by subtracting positron emission tomography (PET) data recorded during the warm hypnosis- control condition from the ↑ pain (Int or Unp) and the ↓ pain (Int or Unp) conditions and the ↑–↓ pain (Int or Unp) involved subtracting ↓ pain (Int or Unp) condition from the ↑ pain (Int or Unp) condition. Horizontal and sagittal slices through S1 and ACC, respectively, are centered at the activation peaks observed during the relevant suggestion condition.
CNS properties of low inspired tension of N2O include Sevoﬂurane (Ultane) is the most recently introduced in- periods of waxing and waning consciousness clonidine 0.1 mg on-line, amnesia, halation anesthetic. With this con- makes it useful for outpatient and ambulatory proce- centration, responses to painful surgical manipulations dures. It has the advantage of not being pungent, a char- are blocked as effectively as they would be with a thera- acteristic that permits a smooth inhalation induction, peutic dose of morphine. Since the tissue solubility of N2O is low, the it does not directly produce tachycardia, it is a useful al- CNS effects are rapid in onset, and recovery is prompt ternative to consider in patients with myocardial isch- when the patient is returned to room air or oxygen. However, a concern for reﬂex-induced tachycar- The most common use of N2O is in combination with dia remains. It decreases the Sevoﬂurane undergoes hepatic biotransformation dosage requirement for the other anesthetics, thus lower- (about 3% of the inhaled dose), and it is somewhat de- ing their cardiovascular and respiratory toxicities. The degrada- ample, an appropriate anesthetic maintenance tension tion product from the absorbent has been reported to for N2O and halothane would be N2O 40% and be nephrotoxic, although the report is controversial and halothane 0. MECHANISM OF ANESTHETIC ACTION Nonhalogenated Inhalational Anesthetics Among the earliest proposals to explain the mechanism In contemporary surgical settings, the only useful non- of action of anesthetics is the concept that they interact halogenated inhalational anesthetic is N2O. Earlier physically rather than chemically with lipophilic mem- agents, ether and cyclopropane, have fallen out of favor, brane components to cause neuronal failure. However, since they present a serious safety hazard due to their this concept proposes that all anesthetics interact in a ﬂammability and explosiveness. They remain interesting common way (the unitary theory of anesthesia), and it from a historical point of view, since they were among is being challenged by more recent work demonstrating the ﬁrst developed. Proposals for N2O (commonly called laughing gas) produces its anes- the production of anesthesia are described next. Although it directly depresses the myo- Anesthesia from Physical Interactions cardium, cardiac depression is offset by an N2O– with Lipophilic Membrane Components mediated sympathetic stimulation. Tidal volume falls, but minute ventilation The idea that a physical interaction is important stems is supported by a centrally mediated increase in respi- from experimental observations made in the late nine- ratory rate. However, since the respiratory depressant teenth and early twentieth centuries, when it was recog- effect of N2O are synergistic with drugs such as the opi- nized that noble gases such as xenon, which do not 306 IV DRUGS AFFECTING THE CENTRAL NERVOUS SYSTEM chemically interact with tissues, produce unconsciousness.