By Q. Zarkos. West Chester University of Pennsylvania.
Even then purchase inderal master card, regulatory actions to remove thimerosal and other mercury compounds from medical products proceeded at a glacial pace effective 80mg inderal. The decision to remove thimerosal from topical ointments was not finalized until 1998 order inderal 80 mg with visa. The removal of thimerosal from several childhood vaccines in the United States wasn t accomplished until after the turn of the century order cheap inderal line. Today, the vaccine for influenza given to infants still contains trace amounts of ethylmercury. It appears that nobody analyzed the potential impact of the increased cumulative amount of mercury to which young children were being exposed. It is no wonder that, in its report on thimerosal, the Institute of Medicine commented: "The presence of mercury in some vaccines can raise doubts about the entire system of ensuring vaccine safety, and late recognition of the potential risk of thimerosal in vaccines may contribute to a perception among some that careful 138 attention to vaccine components has been lacking. Thimerosal Manufacturers Accumulated Evidence of the Toxicity of Thimerosal Eli Lilly and Company of Indianapolis licensed thimerosal in 1930. However, it now appears that very little research on the safety or effectiveness of thimerosal was ever done. Eli Lilly was not the only manufacturer of thimerosal or other ethylmercury products. However, Eli Lilly initially patented this product and had a longer history with it than any other company. Therefore, it is appropriate to review Lilly s track record in ensuring the safety and reliability of this product. A review of internal Eli Lilly documents dating back 70 years suggests that the only study of thimerosal involving human subjects was done prior to 1930. For the next seven decades, Lilly spokespeople would refer to that original study as evidence of thimerosal s safety. As previously discussed in this study, an intravenous solution containing thimerosal was tried as an experimental treatment for 22 men who were seriously ill with Meningitis. While the treatment was found to be ineffective, the doctor who conducted the study concluded that the 139 solution caused no harmful side effects. It is clear today that such a limited number of subjects, all suffering from the same serious illness, would hardly qualify as a sufficiently sized 138 Institute of Medicine, Immunization Safety Review Committee; Immunization Safety Review Thimerosal- Containing Vaccines and Neurodevelopmental Disorders; October 2001; Pg. Burrows, responded with a ringing defense of Lilly s product on February 14, 1973: Due to the length of time this product has been on the market, its efficacy and safety have been proven by over forty years of use throughout the world. Because of this long period of use, it would be difficult to get recognized researchers to conduct new studies for safety or efficacy. They believe that over forty years of wide usage has proven efficacy and safety beyond that which could be done in 141 special studies. Our experience with the solution ought to serve as a warning and certainly in the face of that warning we ought not to advocate the use of the stronger products without some pretty definite evidence that we will not repeat 142 our solution experience. It is therefore preferable to use the minimum amount of this preservative 143 necessary to maintain the sterility of the product. In the absence of appropriate data, a positive recommendation could not be made, this use does not seem unreasonable and probably would not 144 be hazardous. Although these papers and case reports strongly suggested the need for much more research, there apparently was little follow- up. In other words, Merthiolate is unsatisfactory as a preservative for serum intended for use on dogs. Occasional dogs do not show the local reaction, but in some instances, the reaction is extremely severe. I might say that we have tested Merthiolate on humans and find that it gives a more 147 marked local reaction than does phenol or tricresol. Crumley, Merthiolate in Parenteral Products, (December 14, 1972) 146 Eli Lilly Memorandum from W. Jamieson, Director of Biological 59 Mercury in Medicine Taking Unnecessary Risks A 1947 paper published by an Army physician in Baltimore reported that Merthiolate was causing contact dermatitis in his patients. He concluded: No eruptions or reactions have been observed or reported to Merthiolate internally, but it may be dangerous to inject a serum containing Merthiolate into 148 a patient sensitive to Merthiolate. She reportedly suffered chills and fevers and had small vesicles and erythema in the area of her Merthiolate application. After her recovery, the patient indicated that the ulcer for which she was being surgically treated appeared after repeated application of a tincture of Merthiolate. She continued applying the Merthiolate until her skin became too raw and painful to continue use, and then 149 sought medical care. A 1950 New York Academy of Sciences article entitled, Mercurials as Antiseptics, found that Merthiolate is toxic when injected parenterally and therefore cannot be used in 150 chemotherapy. Later in 1973, Lilly s legal department recommended new labeling language for thimerosal 152 products: Do not use when aluminum may come in contact with treated skin. As one facet of this review, a panel of experts was assembled to review the safety and efficacy of over-the-counter drugs containing mercury. It reviewed 18 products containing mercury, and found them all either unsafe or ineffective for their stated purpose of killing bacteria to prevent 153 infections. The study determined that thimerosal was 35 times more toxic to the heart tissue it was meant to protect than the bacteria it 155 was meant to kill. In terms of safety, the panel cited a number of studies demonstrating the highly allergenic nature of thimerosal and related organic mercury products. They stated that while organic mercury compounds like thimerosal were initially developed to decrease the toxicity of the mercury ion, thimerosal was actually found to be more toxic than bichloride of 157 mercury for certain human cells. It is not effective as a topical antimicrobial because its bacteriostatic action can be 158 reversed. The submission of the committee s report in 1980 set in motion a tortuous bureaucratic process that would not result in the banning of mercury from over-the-counter products until 1998. What makes the glacial pace of these proceedings all the more mystifying is that there appears to have been no opposition to this action throughout the process. Surely there must have been concern that if it was not safe to apply ethylmercury to the surface of an individual s skin, it might not be safe to inject ethylmercury deep into an infant s tissue. This debate, which at times pitted one health-care bureaucracy against another, spanned nearly three years. Given the fact that almost twenty years had passed since an expert panel had determined that thimerosal was unsafe in topical ointments, it is surprising that there was any further debate at all. There was tremendous reluctance on the part of some officials to admit that a mistake had been made in allowing ethylmercury to be used in vaccines. There was great uncertainty in others caused by the lack of data specifically on ethylmercur y. However, the institutional resistance to change was counter-balanced by the growing realization that there was more ethylmercury in childhood vaccines than previously thought, and that nobody had thought to calculate the cumulative amounts. It will also raise questions about various advisory bodies regarding aggressive recommendations for use. Conversion of the percentage thimerosal to actual micrograms of mercury involves ninth grade algebra. In 1999, when the Federal government could have ordered thimerosal removed from vaccines by a specific date, or stated a preference for thimerosal- free vaccines, a statement was instead issued asking for a commitment from vaccine manufacturers to eliminate or reduce mercury in vaccines as expeditiously as possible. As a result, thimerosal-containing vaccines that remained in stock in doctors offices continued to be used. In point of fact, we have no proof that in 2003, some children in the United States are not still receiving thimerosal-preserved vaccines that have lingered in medical offices or clinics. With the exception of the influenza vaccine, all major childhood vaccines were being 165 Email from Dr. The task of analyzing the amount of mercury in vaccines and its ramifications was assigned to Dr. Despite the general lack of scientific research on the toxicity of ethylmercury, their review of the available literature led to two working conclusions: 1. The recommended guidelines for exposure to methylmercury were a good starting 166 point for reviewing exposure to ethylmercury; and 2. Ball, which concluded that: no scientific database to take regulatory actions and to recommend to take thimerosal either out of vaccines or to leave it in. In fact, somebody should perform the adequate studies to come to a conclusion on the toxicity of thimerosal 167 or its metabolized forms. Hasting s conclusion was sharp: I disagree about the conclusion regarding no basis for removal of thimerosal. On a strictly scientific basis, yes, there are no data that have looked at the specific issue of thimerosal in vaccines.
In 1948 Marius Kolsrud at the University of Oslo pre- sented a master thesis with the title; Godfrey Hounsfeld Allan Cormack Rntgen-skikt-avbildning order inderal 80 mg without prescription. Kolsrud made equipment that made it possible to take x-ray pictures of a single plane in the object cheap 40 mg inderal visa. Consequently purchase inderal toronto, structures in the focal plane appear sharper order inderal 40 mg, while structures in other planes appear blurred. It is thus possible to select different focal planes which contain the structures of interest. This method was used for chest x-ray pictures in connection with tuberculo- sis for a number of years. This technique uses x-ray fuo- roscopy to guide the compression of plaques and minimize the dangerous constriction of the heart vessels. The signal from the x-ray system is con- verted to a digital picture which can then be enhanced for clearer diagnosis Andreas Gruentzig and stored digitally for future review. The physical basis for an x-ray picture The x-ray picture is a shadow picture of the part of the body that is between the x-ray tube and the flm. Only the x-ray photons that penetrate the object and reach the flm can give a signal or blacken- ing of the flm. To see into the body we must have something that can penetrate the body come out again and give information. The fgure below is an attempt to illustrate the main points for making an x-ray photo. The two drawings one vertical and one hor- Incoming x-ray photons izontal are attempts to illustrate the basic principles for an x-ray photo. Absorber Part of the body Transmitted Electron photons The x-rays is absorbed according to the electron density Incoming photons Detector Scattered flm, fuoeresent screen, etc. The x-ray source On page 8 we described the basic principles for the formation of x-rays or rather bremstrahlung. When electrons with high energy smash into the anticathode a tiny part of the energy is trans- formed into radiation. This implies that the x-ray photons formed, may have a number of different energies in fact a whole spectrum is formed (the Initial spectrum in the fgure below). X-rays are usually described by their maximum energy, which is determined by the voltage between the electrodes. The amount or frac- tion of the electron energy that is transformed into x-rays from the anode surface is only about a percent of the electron energy. This implies that most of the energy is dissipated as heat, and consequently the anode must be cooled. The probability for transferring the elec- tron energy into radiation is proportional to Z E. The result is a spec- trum in the fgure called initial spectrum In order to use the radiation it must get out of the X-ray tube. The spectrum changes like that illustrated above from the initial spectrum into the fnal spectrum. For example, if low energy x-rays are needed, a beryllium window is used since this window has much lower density than a glass window. The spectrum also contains characteristic x-rays from dislodging of K- and L-shell electrons from the target. This will not be further discussed when the x-rays are used for diagnostic purposes, but is important for x-ray crystallography. We are not going to describe all the technological developments with regard to the control of the exposure time and equipment for the different types of examinations. Thus, in the case of mammography the maximum energy is low (below 30 kV) whereas in skeletal and abdominal examinations the energy is larger, between 60 to 85 kV. Another aspect is that the radiation dose in an examination should be kept as low as possible. Several developments using intensifying screens have reduced the exposure (see below). Absorption and scattering in the body The x-ray picture is based on the radiation that penetrates the body and hit the detector (flm). The details in the picture are due to those photons that are absorbed or scattered in the body. Since both the absorption and the scattering depend upon the electrons in the object (body) we can say that; the x-ray picture is a shadow-picture of the electron density in the body. Since x-ray diagnostic uses low energy radiation only the photoelectric effect and the Compton scattering contribute to the absorption. The photoelectric effect occur with bound electrons, whereas the Compton process occur with free or loosly bound electrons. Both processes vary with the radiation energy and the atomic number of the absorber. Photoelectric effect variation with photon energy For the energy region in question and for atoms like those found in tissue the photoelectric cross- section varies with E 3. Photoelectric effect variation with atomic number The variation with the atomic number is quite complicated. For an energy above the absorption edge, the cross-section per atom varies as Z4 (i. Compton effect variation with photon energy For the energy range used for diagnostic purposes the Compton effect is rather constant and de- creases slightly with the energy. Compton effect variation with atomic number The Compton process increases with the electron density of the absorber. This implies that the absorption in bones (with an effective atomic number of about 13) is much larger than that for tissue (with effec- tive atomic number of about 7. For energies below about 30 keV the absorption is mainly by the photoelectric effect. In this energy region it is possible to see the small variations in electron density in normal and pathological tissue like that found in a breast. It can be noted that due to the strong dependence of the photoelectric effect with the atomic number we fnd the key to the use of contrast compounds. Thus, compounds containing iodine (Z = 53) or barium (Z = 56) will absorb the low energy x-rays very effciently. The Compton process varies slightly with the energy in this range and is the dominating absorp- tion process for energies above 50 keV. In Rayleigh scattering the photon interacts with a bound electron and is scattered without loss of energy. In Thomson scattering the photon interacts with a free electron and the radiation is scattered in all directions. The two elastic scattering processes accounts for less than 10 % of the interactions in the diagnostic energy range. The purpose for discussing these details about absorption and scat- tering is to give some background knowledge of the physics of the x-ray picture. It is differential attenuation of photons in the body that produces the contrast which is responsible for the information. The attenuation of the radiation in the body depends upon; the density, the atomic num- ber and the radiation quality. In mammography one are interested in visualizing small differences in soft tissue and we use low energy x-rays (26 28 kV) to enhance the tissue details. In the case of chest pictures the peak energy must be larger because the absorbing body is very much larger and some radiation must penetrate the body and reach the detector. It is the transmitted photons that reach the detector that are responsible for the picture. The detector system A number of different detectors (flm, ionization chambers, luminescence and semiconductors) have been used since the beginning of x-ray diagnostic. The x-ray picture was created when the radiation was absorbed in the flm emul- sion consisting of silver halides (AgBr as well as AgCl and AgI). In the usual morning meeting the doctors were often gath- ered in front of the light box to discuss the patients (see illustration). Consequently, in order to increase the sensitiv- ity, intensifying screens were introduced. The screen is usually a phosphor scintillator that converts the x-ray photons to visible light that in turn expose the flm. The introduction of intensifying screens was made already in 1896 by Thomas Alva Edison.
The latter ones have been found in the blood of humans after induction of physical urticaria or allergic asthma order 40mg inderal overnight delivery. Mediators with Enzymatic Properties Two important proteases are found in human mast cells and not basophils buy inderal canada. Tryptase ( 51) buy cheap inderal 40mg online, a tryptic protease of 140 purchase 40mg inderal,000 daltons, is present in all human mast cells. It constitutes nearly 25% of mast cell granular protein and is released during IgE-dependent reactions. It is capable of cleaving kininogen to yield bradykinin, diminish clotting activity, and generate and degrade complement components such as C3a and a variety of other peptides. Tryptase is not inhibited by plasma antiproteases, and thus its activity may be persistent. It is present in plasma in patients experiencing anaphylaxis and in those with systemic mastocytosis. The amount and ratio of a and b subtypes have proved useful markers in these disorders ( 52). Its true biologic role is unclear, but it enhances smooth muscle reactivity and is a mitogen for fibroblasts, increasing their production of collagen ( 53,54). A chymotryptic protease termed chymase is present in a subclass of human mast cells, particularly those in the skin and on serosal surfaces, and has thus been used as a marker to identify connective tissue mast cells. Structural Proteoglycans The structural proteoglycans include heparin and various chondroitin sulfates. Heparin 6 Heparin is a highly sulfated proteoglycan that is contained in amounts of 5 pg/10 cells in human mast cell granules (55) and is released on immunologic activation. Human heparin is an anticoagulant proteoglycan and a complement inhibitor, and it modulates tryptase activity. Human heparin also may be important in angiogenesis by binding angiogenic growth factors and preventing their degradation, and it is essential for the proper packaging of proteases and histamine within the mast cell granule. Chondroitin Sulfates Human basophils contain about 3 to 4 pg of chondroitin 4 and 6 sulfates, which lack anticoagulant activity and bind less histamine than heparin. Human lung mast cells contain highly sulfated proteoglycans, chondroitin sulfates D and E, which accounts for the different staining characteristics of these mast cells. These molecules may be central to local regulation of mast cell growth and differentiation and may also provide new functions for mast cells in health and disease. Given the number of mediators, the knowledge that many have yet to be purified (or even identified), and the lack of understanding of appropriate ratios of mediators generated or released in vivo, it is not surprising that there are no reliable data regarding these interactions in health or disease. The number and type of mast cell mediator interactions are potentially enormous, and their pathobiologic consequences are relevant to a variety of homeostatic and disease processes. The best clues to the interaction of mediators are the known physiologic and pathologic manifestations of allergic diseases. It is hoped that the valuable tool of gene knockouts in mice will elucidate critical individual and interactive roles of these molecules. The participation of other immunoglobulin classes and immunologically activated cells, and thus of other inflammatory pathways, is excluded in such studies by using purified IgE to sensitize nonimmune individuals passively. Histologic analysis of the initial response shows mast cell degranulation, dermal edema, and endothelial cell activation. Similar studies of lung tissue responses, employing passive sensitization or mast cell deficient subjects, have only been possible in mice. In humans, a similar dual-phase reaction is experienced by allergic patients who inhale antigen, but the participation of immunoglobulins other than IgE and of activating cells other than mast cells cannot be excluded, therefore complicating assessment and preventing unambiguous assignment of any response to a particular immunologic pathway. Such challenges result in an immediate bronchospastic response followed by recovery, and, 6 to 24 hours later, by a recrudescence of asthmatic signs and symptoms ( 61). The mediators responsible for these pathophysiologic manifestations have not been delineated fully, but clues to their identity can be derived from knowledge of the effects of pharmacologic manipulation, by the identification of mediators in blood or tissue fluid obtained when the inflammatory response occurs, and by the known effects of isolated mediators. Pharmacologic intervention suggests that the initial phase is mast cell dependent in both skin and lung tissues. The initial response in skin may be inhibited by antihistamines, and in the lungs by cromolyn. In both tissues, corticosteroids effectively inhibit only the late response, reflecting its inflammatory nature. The late response is associated with2 leukocyte infiltration and cytokine release, but not with a unique profile of released mediators. This concept is supported by the knowledge that the early response occurs before a significant influx of circulating leukocytes. In response to mediators, vascular endothelium, fibroblasts, and a variety of connective tissue and epithelial cells then could generate other inflammatory and vasoactive mediators. The late phases in lung and skin tissue are likely to represent the residue of the early response as well as the contribution of active enzymes, newly arrived plasma inflammatory cascades, various cytokines (particularly those inducing endothelial expression of adhesion molecules) ( 57), and the influx of activated circulating leukocytes. The late inflammatory response is relevant to the progression of asthma in that patients experiencing the late responses have exacerbation of their nonspecific bronchial hyperreactivity, whereas this phenomenon does not occur after isolated early responses. Because mast cells are positioned near small blood vessels and at the host environment interface, and are thus at crucial sites for regulating local nutrient delivery and for the entry of noxious materials, the potential regulatory role of mediators is obvious. They are likely to be especially important in the regulation of flow through small blood vessels, impulse generation in unmyelinated nerves, and smooth muscle and bone structural integrity and function. The ability to recruit and activate plasma proteins and cells may also provide preimmune defense against host invasion by infectious agents. Such a role is most apparent in parasitic infestation but is also likely in the case of other insults. Moreover, the recognition of mast cell heterogeneity implies that differences in mast cells relate to locally important biologic requirements. Although the homeostatic and pathophysiologic role of mast cell mediators is understood imprecisely, the broadening understanding of their chemical nature and function provides a useful framework for addressing their role in health and disease. The diverse potential effector and immunoregulatory roles of mast cells in allergic disease. Ribonuclease-gold ultrastructural localization of heparin in isolated human lung mast cells stimulated to undergo anaphylactic degranulation and recovery in vitro. Dependence of mast cell IgE-mediated cytokine production on nuclear factor-kB activity. Clinical manifestations of the release of histamine and other inflammatory mediators. Histamine and tryptase levels in patients with acute allergic reactions: an emergency department-based study. Platelet activating factor: a potent chemotactic and chemokinetic factor for eosinophils. Effects of platelet activating factor on pulmonary function and bronchial responsiveness in man. The bronchoconstrictor effects of inhaled prostaglandin D2 in normal and asthmatic men. A prostaglandin J2 metabolite binds peroxisome proliferator-activated receptor gamma and promotes adipocyte differentiation. IgE-dependent activation of cytokine primed mouse cultured mast cells induces a delayed phase of prostaglandin D2 generation via prostaglandin endoperoxidase synthase 2. Molecular cloning and characterization of a second human cysteininyl leukotriene receptor: discovery of a subtype selective agonist. A3 adenosine receptor activation triggers phosphorylation of protein kinase B and protects rat basophilic leukemia 2H3 mast cells from apoptosis. Release of neutrophil chemotactic activity during immediate hypersensitivity reactions in humans. Increased biosynthesis of platelet activating factor in activated human eosinophils. Development of a new, more sensitive immunoassay for human tryptase: use in systemic anaphylaxis. Effect of mast cell-derived mediators and mast cell-related neutral proteases on human dermal fibroblast proliferation and type 1 collagen production. Second-generation, nonsedating H 1 receptor antagonists, many of which have been derived from first-generation agents, have added a new dimension to the treatment of allergic disorders.