By Y. Fabio. State University of New York College at Oswego. 2018.
In the latter case order rumalaya forte 30pills visa, crystals form and there are fewer free ions available to make up the half-cell (Warner 30 pills rumalaya forte otc, 1972). To conclude this discussion of characteristics that make up a good elec- trode, it must be emphasized that the physical attachment of the electrode should be firm enough to restrict lateral motion and electrolyte drying, yet not so firm that it hinders the movement of the subject. The electrodes should be as similar as possible, with a low half-cell potential, such as found with the MUSCLE ACTIONS REVEALED THROUGH ELECTROMYOGRAPHY 48 Ag/AgCl combination. If these are used, they should be cleaned gently, after each application, to keep the silver chloride coating intact. Electrophysiology Until now, we have tacitly assumed that there is some activity under the skin that is worth measuring. At this stage it is worthwhile to consider the under- lying physiological processes that cause an electrical voltage to appear on a persons skin. Of necessity the discussion will be brief, but you are encour- aged to refer to other excellent books on this topic (Loeb & Gans, 1986; Webster, 1976). At the risk of oversimplifying the physiological processes that result in a nerve impulse being transmitted down a nerve axon, Figure 4. In this diagram a dipole (a small object with a positive and negative charge at each end) is moving along a volume conductor. A differential amplifier records the difference between the potentials at Points A and B on the conductor. Initially there is no difference between these points, so the output from the amplifier is zero. However, as the dipole approaches Point A, this point becomes negative with respect to B, and there will be some negative output. Not only does Point B start to register the approaching negative charge, but Point A begins to feel the effect of the positive charge at the other end of the dipole. Finally, when Point B registers the positive end of the dipole, and Point A has returned to zero potential, the quantity A-B is slightly negative. Refer to the text for an explanation of the way that the triphasic signal (b) is generated. It should be noted that a single axon leading to a muscle is responsible for the innervation of as few as 3 or as many as 2,000 individual muscle fibres (Win- ter, Rau, Kadefors, Broman, & DeLuca, 1980).
Whilst pharmaceutical companies necessarily use scientific methods to evaluate the drugs that they themselves have developed buy rumalaya forte 30pills with mastercard, the choices as to which are subjected to the most expensive Phase III trials buy rumalaya forte 30pills without a prescription, or indeed the initial choices as to which drugs are developed, must – in their terms – be subject to a commercial judgement on their part. This would involve making a judgement about the size of the market for such a drug, and its likely profitability, as well as, of course, making a judgement about its likely efficacy. It would be reassuring to believe that only a scientific basis was used to decide which drugs were subject to Phase III trials, but generally there are far more drugs that could be subject to such trials than the funding available, and it is clear that commercial as well as scientific factors must intrude in the selection process. Such a process, at least from a commercial point of view, is likely to relegate drugs with a potentially low profitability, or which cannot be patented. The history of therapeutic possibilities in MS is littered with the hopes of people often for non- patentable substances in relation to the disease – such as evening primrose oil, hyperbaric oxygen and, most recently, cannabis. It is very unlikely that pharmaceutical companies would be involved in testing such substances unless they can patent a variant of the substance concerned, and thus usually – as in the case of all three substances RESEARCH 195 mentioned – medical charities and/or the government-funded Medical Research Councils themselves would need to fund such trials. Such funding may occur in response to the continuous and widely expressed concerns of people with MS, although decisions for this kind of funding are not normally justified on this basis. Finally, it is worth saying that, although some major potential therapeutic advances will remain untested because of the particular focus of the pharmaceutical companies, this is unlikely because of the significant number of checks and balances made by the Multiple Sclerosis Society and the Medical Research Council. Participating in a clinical trial First of all it is important to say that, if you participate in a clinical trial (especially a Phase III trial) for MS, it will generally not be guaranteed that you will receive the new drug – but you will indeed have a chance to take it, probably on the basis of being randomized to the ‘treatment group’. You will probably have a 50–50 chance of receiving the new drug or being randomized into the ‘control’ group, who will use either a placebo or another comparison drug. However, there are several reasons why it is still worth your while joining a clinical trial, even if you are not given the new drug by being randomized to a comparison group: • To be frank, it is likely that you will receive more careful clinical assessment and support, than you otherwise would do, if you participate in a clinical trial, whether you receive the new drug or not. This is because all those participating have to be meticulously and regularly monitored. Indeed the comparison drug will already have been shown to effective in managing some aspects of MS, and often the new drug is one in which only a marginal additional assistance for MS is hoped for – but not yet known. In Britain the major means of recruitment is usually directly through your neurologist. When they are notified of a particular trial, they will investigate their own lists of people with MS to see whether any are suitable for the trial.
