Glyset

Daniel P. Cardinali, MD, PhD

• Department of Physiology, Faculty of Medicine,
• University of Buenos Aires, Buenos Aires, Argentina

The aircraft should be pressurized to an altitude of 500 feet or less to prevent further bubble formation and expansion buy glyset in united states online. This may have the effect increasing intracranial pressure and reducing ventilation glyset 50 mg fast delivery. However purchase glyset 50mg line, an unconscious per son may be placed in the lateral decubitus position to prevent aspiration cheap 50 mg glyset visa. The patient should be supine purchase genuine glyset on-line, neck in the neutral head position buy generic glyset 50mg on line, and uncramped with the extremities uncrossed. The patient should not be per mitted to sleep, so that changes in neurological status will be readily detected. Free water solutions such as D5W should be avoided as they may contribute to cerebral swelling. Inflatable cuffs, such as endotracheal cuffs, should be filled with water, not air. Flying After Diving Required intervals between diving and flying are given in Table 1-14. Table 1-14 Flying After Diving Category Surface Interval Before Flight Flight Crew 24 hours Divers No-Decompression Dive 12 hours Decompression Dive 24 hours (nonsaturation) Saturation Dive 72 hours l-73 U. The flight surgeon should conduct a complete fitness to continue physical examination. The aeromedical disposition is made based on diagnosis, classification, treatment course, and du ty status. Any documented history of gas embolism should be worked up for pulmonary bullae and other causes of Pulmonary Overinflation Syndrome as well as for atrial septal defects. Observation Time and Travel Restrictions Following Hyperbaric Recompression the required intervals between the completion of recompression treatment and travel in pressurized nontactical aircraft are given in Table I-15. However, excessive amounts of oxygen or excessively high oxygen partial pressures can be detrimental or even fatal. The amounts of oxygen and oxygen partial pressures breathed by aviation personnel are usually not great enough to cause significant harm to the body. However, the problem of oxygen toxicity is more significant in underwater and hyperbaric operations where the partial pressures of the breathing gases are excessive. The harmful effects of elevated partial pressures of oxygen are directly related to the level of elevation of partial pressures and the duration of exposure. It is sometimes called the Lorraine Smith Effect after the researcher who first described it. Pulmonary oxygen toxicity begins with a progressive hydration or fluid accumulation of the lungs under hyperoxic condi tions. The pulmonary edema leads to greater mechanical difficulties in ventilation together with impaired gas transfer. The individual finds it harder to breathe; he may feel a deep substernal pain and if not returned to a subtoxic breathing mix he may become hypoxic as the alveolar walls swell and the edema further impairs oxygen diffusion. Thus a paradoxical situation is reached in which elevation of the oxygen level in the gas ventilating the lungs actually decreases blood ox ygenation in the pulmonary capillaries. Pulmonary oxygen toxicity can progress to a point where hypoxia can result in death unless the alveolar oxygen pressure is elevated to increase the oxygen diffusion gradient to elevate the arterial oxygen pressure. This does provide temporary relief but also causes further edema, a fur ther reduction in the oxygen diffusion capacity and an eventual return to hypoxia until a still higher inspired oxygen pressure is required and so the subject enters a vicious cycle which can on ly terminate in death. The only known treatment for pulmonary oxygen poisoning is reduction of the inspired oxygen partial pressure to less than 0. Central Nervous System Oxygen Toxicity the onset of neurological oxygen toxicity can be quite sudden and dramatic. It is manifested by generalized convulsions, indistinguishable from the convulsions of grand mal epileptic seizure. Central nervous system oxygen toxicity usually occurs when an individual is exposed to inspired oxygen partial pressures about 1. Muscular twitching particularly lip twitching can precede a con vulsion but no reliance can be placed on this as an early warning. Acceleration Atelectasis Another oxygen effect which may be loosely grouped under the general heading of oxygen tox 1-76 Physiology of Flight icity is atelectasis while breathing 100 percent oxygen during + Gz acceleration, although the term oxygen toxicity in this context is a misnomer. Acceleration atelectasis is included in this section only because it occurs when an aviator is breathing 100 percent oxygen. The primary factor responsible for the atelectasis is probably the complete cessation of basilar alveolar ventilation under acceleration. There is also markedly increased blood flow to the basilar alveoli as opposed to the apical ones, along with a reduction in basilar alveolar volumes as the weight of the lung under acceleration compresses the bases against the diaphragm. With these factors acting in con cert, and when the alveoli in question contain only oxygen, water vapor, and carbon dioxide, ox ygen absorption (the main cause of acceleration atelectasis) leads to alveolar collapse, and atelec tasis can occur very rapidly. If nitrogen is present in the inspired gas, the gas absorption and consequent alveolar collapse are greatly slowed. The time required for complete absorption of gas contained in the lower quarter of the unventilated lung, with normal blood flow distribution, is increased from five minutes on 100 percent oxygen to about 25 minutes on 50 percent oxygen, 50 percent nitrogen. In addition, there is evidence that nitrogen in the lung acts as a spring by preventing alveolar col lapse when all the oxygen is absorbed. Pulmonary atelectasis during flight may result in several performance-degrading effects, in cluding distracting or perhaps even incapacitating cough and chest pain and arterial hypoxia due to the shunt of venous blood through the nonaerated alveoli. The Flight Surgeon should remain aware that coughing, substernal pain, and decreased altitude tolerance may indicate the develop ment of this condition. In any event, acceleration atelectasis usually resolves itself in a few days with little or no treatment. Oxygen Paradox Restoration of normal alveolar oxygen tension in a hypoxic individual may be accompanied by a temporary increase in severity of symptoms, a phenomenon known as oxygen paradox. The paradox occurs when reoxygenation is brought about suddenly and in severe cases it can result in muscle spasms and unconsciousness which may last from a few seconds up to a minute. Accompanying effects are decreased vision, mental confusion, diz ziness and nausea. The ensuing hypocapnia leads to cerebral vasoconstriction and systemic vasodilation. In addition the hyperventilation results in a respiratory alkalosis shifting the oxyhemoglobin dissociation curve upward and to the left (Bohr Effect). This shift increases the capacity of the blood to onload oxygen in the lungs but restricts offloading of oxygen at the tissue level. The combined effects of vasodilation of blood vessels in the extremities, vasoconstriction of cerebral blood vessels, and the shift of the oxyhemoglobin curve to the left reduces blood flow and oxygen supply to the brain (stagnant hypoxia). Upon restoration of oxygen, there is a reduction or cessation of breathing and a hypotension. The hypotension produced by the restoration of oxygen is probably due to vasodilation, which occurs by the direct action of oxygen on the pulmonary vascular bed. The hypocapnic effects of hypoxia and the apnea or reduction of ventilation and hypotension which follow reoxygenation, combine to further reduce cerebral blood flow. This further reduc tion in blood flow in all probability intensifies an already existing cerebral hypoxia for a short period of time until the cardiovascular effects have passed and carbon dioxide tension returns to normal. Once arterial carbon dioxide tension returns to normal, it will stimulate the central respiratory chemoreceptors to resume ventilation and resolve the cerebral hypoxia. Oxygen Equipment the ability to offset the physiological effects of reduced barometric pressure is as important to the effectiveness of a mission as the aircraft itself. Oxygen equipment is one area of development that has enabled man to fly in the environment above 10,000 feet. Aircraft Oxygen Systems Aircraft oxygen systems provide the aircrew member with diluted or 100 percent oxygen for breathing. Aircraft oxygen systems installed in naval aircraft fall in one of the following categories: 1. Gaseous oxygen systems are used primarily in emergency oxygen systems and in multiplace aircraft where space and weight considerations are less important. Air containing a high percentage of moisture can be breathed indefinite ly without any serious ill effects. However, the moisture affects the aircraft oxygen system in the small orifices and passages in the regulator; freezing temperatures associated with ascent to altitude can clog the system with ice and prevent oxygen from reaching the user. Therefore, ex treme caution must be taken to safeguard against the hazards of water vapor in oxygen systems. In these systems, the breathing oxygen is stored in a yellow, lightweight, nonshatterable cylinder. Shatterproofing is accomplished by heat treating or welding metal bands around the cylinder. On the side of the cylinder painted in black letters are the words Breathing Oxygen, Nonshatterable. The cylinders have an operating pressure range of 50 to 500 pounds per square inch (psi). However, the system is not extremely efficient since the low pressure limits the volume of oxygen. High pressure systems may be aircraft mounted, portable, or contained in seat kits. Liquid oxygen systems are generally used in aircraft where space, weight and mission considerations are paramount. A li quid oxygen converter assembly is designed to store and convert liquid oxygen into gaseous ox ygen. A typical liquid oxygen converter assembly s 1-22, 1-23) consists of a container sphere, buildup and vent valve, relief valve, and associated tubing and fittings. A capacitance type probe assembly which sends an electric signal to a liquid oxygen quantity gauge that is located in the aircraft is incorporated within the sphere. Oxygen in its liquid state is stored in the spherical assembly 1-22) which consists of an inner and outer shell separated by an an nular space!. The annular space is evacuated, creating a vacuum, preventing the transmittal of heat through the space. The potential hazards associated with the handling of liquid oxygen are due to its extremely cold temperature, rapid expansion upon conversion to gas at ambient (room) temperature, and its reactivity with any organic matter or flammable substance with which it comes in contact. Because liquid oxygen has an extremely low temperature (Boiling point 183 F, Storage temp. Injuries to the skin resulting from contact with liquid oxygen should be treated as frostbite or similar hypothermic injuries. Under the right conditions of temperature and pressure liquid oxygen may react violently with any organic matter, particularly that containing hydrocarbons. Mere mixture of liquid oxygen with powered organic materials under certain conditions may cause an explosion. If liquid oxygen is vaporized and warmed to ambient temperature, one volume of liquid oxygen will expand to 862 volumes of gaseous oxygen. In the aircraft this expansion ratio results in a sav ing of approximately 82 percent in weight and approximately 75 percent in space. Weight and 1-80 Physiology of Flight space are critical in a jet propelled aircraft because for every pound removed from the aircraft ap proximately two pounds of thrust are gained. Liquid oxygen systems work on low pressure [110 psig mix] and must be vented to prevent over pressurization. Liquid oxygen demonstrates a high affinity for absorption of impurities and noxious odors, resulting in contamination of complete systems. Suspected impurity contamination of liquid ox ygen in aircraft systems has resulted in abortion of numerous inflight missions. The idea of producing oxygen in flight is very attractive since it minimizes logistic support for oxygen and increases operational safety. These systems include electrochemical concentra tion, fluomine chemical absorption, permeable membrane, and molecular sieve. In the molecular sieve system 1-24) bleed air from the turbine engine is alternately pumped be tween two molecular sieve beds containing aluminosilicate crystals called zeolite. The oxygen-enriched air is then available for use through the normal oxygen delivery system. During the separation process using the two-bed systems, as the first bed is concentrating oxygen, the second bed is removing nitrogen and releas 1-82 Physiology of Flight ing it to the atmosphere. The cycles are then reversed with pressurization of the second bed and exhaustion of the first bed, thus producing a continuous supply of oxygen. The enriched air supply proceeds directly as the bleed air supply pressurizes the system. The onboard oxygen generating system is a revolutionary oxygen system which yields a continuous supply of breathing oxygen to the air crew member with no replenishment requirements. If there is any draw back to the system, it might be the fact that at best this system can only provide 95 percent oxygen, with 5 percent argon. Oxygen Regulators the purpose of an oxygen regulator is to control the flow of oxygen into the oxygen mask, by reducing oxygen pressure to a breathable level. Regulators are designed for either high or low pressure depending on the application.

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The physical environment is one factor order glyset amex, among many order glyset 50 mg without a prescription, that may improve or reduce human well-being discount 50 mg glyset. Climate is one aspect of the physical environment cheap glyset express, and can affect human well-being via economic purchase glyset 50mg with amex, physical purchase cheap glyset online, psychological, and social pathways that influence individual perceptions of quality of life. Climate change may result in lifestyle changes and adaptive behavior with both positive and negative implications for well-being. For example, warmer temperatures may change the amount of time that individuals are comfortable spending outdoors in work, recreation, or other activities, and temperature combined with other climatic changes may alter (or induce) changes in intra and inter-country human migration patterns. More generally, studies of climate change and the United States identify an assortment of impacts on human health, the productivity of human and natural systems, and human settlements. These changes may have consequences, such as a lost job or a more difficult commute, that affect individual well-being directly. In other cases, individual well-being may be indirectly affected due to concern for the well-being of other individuals, or for a lack of cohesion within the community. Completely cataloging the effects of global change on human well-being or welfare would be an immense undertaking. Despite its importance, no well-accepted structure for doing so has been developed and applied. Moreover, little (if any) research focuses explicitly on the impact of global change on human well-being, per se. Next, it presents an illustrative place-based-indicators approach (the typical approach of planners and policy makers to evaluating quality of life in communities, cities, and countries). Approaches of this type represent a commonly accepted way of thinking about well-being that is linked to objective (and sometimes subjective) measures. While a place-based indicators approach has not been applied to climate change, it has the potential to provide a framework for identifying categories of human well-being that might be affected by climate change, and for making the identification of measures or metrics of well-being a more concrete enterprise in the future. To illustrate that potential, the section draws links between community welfare and some of the negative impacts of climate change. Economics has been at the forefront of efforts to quantify the welfare impacts of climate change. This approach is commonly used to support environmental policy decision making in many areas. This section next summarizes the existing 1 economic estimates of the non-market impacts of climate change. An accompanying appendix provides more information on the economic approach to valuing changes in welfare, and highlights some of the challenges in applying valuation techniques to climate impacts. The fourth section of the chapter summarizes some of the key points of the chapter and the chapter concludes with a brief discussion of research gaps. Academic economists, epidemiologists, health scientists, psychologists, sociologists, geographers, political scientists, and urban planners have all rendered their own definitions and statistical indicators of life quality at both individual and community 2 levels. The term welfare is generally used herein to refer narrowly to economic measures of individual well-being, although it is also used in the context of communities in a broader sense. These conceptualizations often also include social and community resources (sometimes referred to as social capital in social scientific literature), such as the presence of voluntary associations, arts, entertainment, and shared recreational amenities (see Putnam, 1993, 2000). The quantity of 3 community resources shared by a population is often called social capital. These components of life quality are interrelated and correlate with subjective valuations of life satisfaction, happiness, pleasure, and the operation of successful democratic political systems (Putnam, 2000). The concepts of well-being, economic welfare, and quality of life play important roles not only in academic research, but also in practical analysis and policy making. Quality of life measures may be used, for example, to gauge progress in meeting policy or normative goals in particular cities by planners; municipalities in New Zealand, England, Canada, and United States have constructed their own metrics of quality of life to estimate the overall well-being and life chances available to citizens. Similarly, health-related quality of life measures can indicate progress in meeting goals. Life quality and human well-being are increasingly important objects of theoretical and empirical research in diverse disciplines. Two analytic approaches characterize the research literature: (1) studies that emphasize well-being as an individual attribute or possession; and (2) studies that treat well-being as a social or economic phenomenon associated with a geographic place. For Coleman, social capital is a store of community value that is embodied in social structures and the relations between social actors, from which individuals can draw in the pursuit of private interest. The scientific basis of such research is that pain and/or discomfort associated with a physiological impairment are registered and experienced variably. Based on patient reports or subjective valuations, psychologists and occupational therapists have developed valid and reliable instruments to assess how mental, developmental, and physical disabilities interfere with the performance and enjoyment of life activities (Bowling, 1997; Guyatt et al. In the new science of happiness, scholars use the tools of neuroscience, experimental research, and modern statistics to discover and quantify the underlying psychological and physiological sources of happiness (for reviews see Kahneman et al. Empirical studies show, for example, that life satisfaction and happiness correlate predictably with marital status (married persons are generally happier than single people), religiosity (persons that practice religion report lower levels of stress and higher levels of life satisfaction), and individual willingness to donate time, money and effort to charitable causes. Similarly, the scholarly literature notes interesting statistical associations between features of climate (such as variations in sunlight, temperature, and extreme weather events) and self-reported levels of happiness, utility, or life satisfaction. Individual valuations of health, psychological, and emotional well-being are sometimes summed across representative samples of a population or country to estimate correspondences between life satisfaction and hard indicators of living standards such as income, life expectancy, educational attainment, and environmental quality. Cross-national analyses generally find that population happiness or life satisfaction increases with income levels and material standards of living (Ng, 2003) and greater personal autonomy (Diener et al. These place-specific variables are seen as exogenous sources of individual life quality. Scholars reason that life quality is a bundle of conditions, amenities, and lifestyle options that shape stated and revealed preferences. In technical terms, the social indicators approach treats quality of life as a latent variable, jointly determined by several causal variables that can be measured with reasonable accuracy. The indicators approach has several advantages in the context of understanding the impacts of climate change on human well-being. First, social indicators have considerable intuitive appeal, and their widespread use has not only made it familiar to both researchers and the general public, but has subjected them to considerable debate and discussion. Second, they offer considerable breadth and flexibility in terms of categories of human well-being that can be included. Third, for many of the indicators or dimensions of well-being, objective metrics exist for measurement. In addition, while its strength is in providing indicators of progress on individual dimensions of quality of life, the indicators approach has also been used to support aggregate or composite measures, at least for purposes of ranking or measuring progress. Various techniques are also available, or being developed, that aggregate or combine measures of well-being. These range from pure data reduction procedures to stakeholder input models where variables are evaluated on their level of social and economic importance. For example, Richard Florida (2002a) has constructed a statistical index of technology, talent, and social tolerance variables to estimate the human capital of cities in the United States. Given the analytical strengths of the social indicators approach, it may be a good starting point for understanding the relationships between human well-being and climate change. These categories represent broad aspects of personal and family circumstances, social structures, government, environment, and the economy that influence well being. The third column, components/indicators of welfare provides examples of the way in which these categories are often interpreted. These components represent what, in an ideal world, researchers would wish to measure in order to determine how a specific society fares from the perspective of well-being. Finally, the last column provides some examples of climate impacts that may be linked to that category. Thus, while the categories and corresponding metrics of well 7 being presented in Table 4. Economics as a source of quality of life refers to a mix of production, consumption, and exchange activities that constitute the material well-being of a geographic place, community, region or country. Standard components of economic well-being include income, wealth, poverty, employment opportunities, and costs of living. Localities characterized by efficient and equitable allocation of economic rewards and opportunities enable material security and subjective happiness of residents (Florida, 2002a). Natural resources, environment, and amenities as a source of well-being refers to natural features, such as ecosystem services, species diversity, air and water quality, natural hazards and risks, parks and recreational amenities, and resource supplies and reserves. Natural resources and amenities directly and indirectly affect economic productivity, aesthetic and spiritual values, and human health (Blomquist et al. Human health as a source of well-being includes features of a community, locality, region or country that influence risks of mortality, morbidity, and the availability of health care services. Good health is desirable in itself as a driver of life expectancy (and the quality of life during those years), and is also critical to economic well-being by enabling labor force participation (Raphael et al. Public and private infrastructure sources of well-being include transportation, energy and communication technologies that enable commerce, mobility, and social connectivity. These technologies provide basic conditions for individual pursuits of well-being (Lambiri et al. Government and public safety as a source of well-being are activities by elected representatives and bureaucratic officials that secure and maximize the public services, rights, liberties, and safety of citizens. Individuals derive happiness and utility from the employment, educational, civil rights, public service, and security efforts of their governments (Suffian, 1993). Finally, social and cultural resources as a source of well-being are conditions of life that promote social harmony, family and friendship, and the availability of arts, entertainment, and leisure activities that facilitate human happiness. The term capital is divided into four types: economic; physical; ecological or natural; and socio-cultural. Communities with greater levels of social and creative capital are expected to have greater individual and community quality of life (Putnam, 2000; Florida, 2002b). In thinking about these indicators, it is important to keep two important contextual realities about climate change and well-being at the forefront. First, while discussions of climate change usually have a global resonance to them, the fact is that the effects of any specific changes in temperature, rainfall, storm frequency/intensity and sea level rise will be felt at the local and regional level by citizens and communities living and working in those vulnerable areas. Therefore, not all populations will be placed under equal amounts of climate change-generated stress. Some will experience greater impacts, will suffer greater damage, and will need more remediation and better plans and resource allocations for adaptation and recovery efforts to protect and restore quality of life (see, for example, Zahran et al. Second, not all citizens in areas more vulnerable to climate change effects are equally at risk. Some population groupings, within the same community, will be more vulnerable and at risk than others. Those who are poorer, minorities, aged or infirmed, and children are at greater risk than others to the stresses of climate change events (Lindell and Perry, 2004; Peacock, 2003). Recognizing that not all citizens of a particular vulnerable area share the same level of risk is something that planners and decision makers must take into account in projecting the likely impacts of climate change events on their populations, and in dealing with recovery of those populations (Murphy and Gardoni, 2008). Finally, the situation is further complicated as climate stressors negatively affect disease conditions in other nations with particularly vulnerable and mobile populations. Increased communicable disease incidence in developing nations have the potential, through legal and illegal tourism and immigration, to affect community welfare and individual well-being in the United States. In any category, multiple indicators could be used; and any one of the indicators could have several measures. Similarly, some indicators are more amenable to objective measurement; others are more difficult to measure, such as measures of social cohesion. The social indicators approach, and the 8 specific taxonomy presented here, are only one of many that could be developed. At the least, different conditions and stakeholder mixes may demand different emphases. All taxonomies, however, face a common problem: how to interpret and use the diverse indicators, in order to compare and contrast alternative adaptive or mitigating responses to climate change. For some purposes, metrics have been developed that that aggregate across individuals or individual categories of well-being and present a composite measure of well-being; or otherwise operationalize related concepts, such as vulnerability (see, for example the discussion of Figure 4. Thus, for example, the counterparts of individual income or health status are, at the social level, per capita income or mortality/illness rates. The concept of community welfare is linked to human communities, but is not confined to communities in urban areas, or even in industrialized cultures.

Other tissue protozoa of potential concern include free-living ameba (Acanthamoeba cheap glyset online, Balamuthia mandrillaris best order for glyset, Naegleria fowleri) and some species of microsporidia including Encephalitozoon cuniculi that commonly cause extraintestinal infection glyset 50mg cheap. Trypanosoma cruzi infection could manifest initially as swelling and redness at the inoculation site 50 mg glyset with mastercard, fever purchase glyset 50mg with visa, rash purchase glyset 50mg on line, and adenopathy. Potential direct sources of infection for laboratory personnel include accidental needle-stick while inoculating or bleeding animals, contact with lesion material from cutaneous leishmaniasis, and contact with blood of experimentally or naturally infected animals. Mosquito-transmitted malaria infections can occur under laboratory conditions as nearly half of the occupationally acquired malaria infections were reported to be vector borne, and contact with body fuids (including feces) of reduviids (triatomines) experimentally or naturally infected with T. Although no laboratory infections with Babesia have been Agent Summary Statements: Parasitic Agents 183 reported, they could easily result from accidental needle-stick or other cutaneous exposure of abraded skin to blood containing parasites. Natural Modes of Infection Leishmaniasis is endemic in parts of the tropics, subtropics, and southern Europe, while malaria is widely distributed throughout the tropics. However, the prevalence of these diseases varies widely among endemic areas; the diseases can be very focal in nature. Birds and mammals, including sheep, pigs, rodents, cattle, deer, and humans can be infected from ingestion of tissue cysts or fecal oocysts and subsequently develop tissue cysts throughout the body. Chagas disease occurs from Mexico southward throughout most of Central and South America, with the exception of the southern-most tip of South America. Leishmania, Plasmodium, and both American and African trypanosomes are all transmitted in nature by blood-sucking insects. Working with infectious oocysts poses the greatest risk of acquiring infection; needle-sticks with material containing tachyzoites or bradyzoites also pose a signifcant risk. One laboratory infection with microsporidia has been reported, associated with conjunctival exposure to spores leading to the development of keratoconjunctivitis. Other intestinal pathogens of concern are some species of microsporidia, specifcally Septata intestinalis and Enterocytozoon bieneusi. Laboratory animal-associated infections with this group of organisms have been reported and provide a direct source of infection for laboratory personnel who are exposed to feces of experimentally or naturally infected animals. Circumstantial evidence suggests that airborne transmission of oocysts of this small organism. Rigid adherence to protocol should reduce the occurrence of laboratory-acquired infection in laboratory and animal care personnel. The organisms in this group do not require more than one host to complete their life cycle because they infect, develop, and result in shedding of infectious stages all in a single host. Agent Summary Statements: Parasitic Agents 187 Affected surfaces should be fooded. Absorb residual hydrogen peroxide with disposable paper towels and allow surfaces to dry thoroughly (10 to 30 minutes) before use. All paper towel litter and other disposable materials should be autoclaved or similarly disinfected before disposal. Reusable laboratory items can be disinfected and washed in a laboratory dishwasher by using the sanitize cycle and a detergent containing chlorine. Alternatively, immerse contaminated items for ~1 hour in a water bath preheated to 50C; thereafter, wash them in a detergent/disinfectant solution. Trematode Parasites Trematode parasites that pose greatest occupational risk are the Schistosoma spp. Fasciola hepatica, the sheep liver fuke, causes fascioliasis, where the adult fukes live in the common and hepatic bile ducts of the human or animal host. Most laboratory exposures to schistosomes would 188 Biosafety in Microbiological and Biomedical Laboratories result in predictably low worm burdens with minimal disease potential. Snails in the family Lymnaeidae, primarily species of Lymnaea, are intermediate hosts for F. Schistosoma mansoni is widely distributed in Africa, South America, and the Caribbean; the prevalence of infection has been rapidly changing in some areas. Infection occurs when persons are exposed to free-swimming cercariae in contaminated bodies of water; cercariae can penetrate intact skin. Ingestion of fuke metacercariae and skin penetration by schistosome cercariae are the primary laboratory hazards. Special Issues Treatment Highly effective medical treatment for most trematode infections exists. Cestode Parasites Cestode parasites of potential risk for laboratorians include Echinococcus spp. Hymenolepis nana, the dwarf tapeworm, is cosmopolitan in distribution and produces hymenolepiasis, or intestinal infection with the adult tapeworm. Natural Modes of Infection the infectious stage of Echinococcus, Hymenolepis, and Taenia is the oncosphere contained within the egg. Canids, including dogs, wolves, foxes, coyotes, and jackals, are the defnitive hosts for E. Echinococcus oligarthrus uses wild felines, 190 Biosafety in Microbiological and Biomedical Laboratories including cougar, jaguarondi, jaguar, ocelot, and pampas cat, as defnitive hosts and various rodents such as agoutis, pacas, spiny rats, and rabbits serve as intermediate hosts. Laboratory-acquired infections with cestodes could result in various clinical manifestations, depending upon the type of cestode. Gloves are recommended when there may be direct contact with feces or with surfaces contaminated with fresh feces of carnivores infected with Echinococcus spp. Agent Summary Statements: Parasitic Agents 191 Special Issues Treatment Highly effective medical treatment for most cestode infections exists. Nematode Parasites Nematode parasites that pose greatest occupational risk include the ascarids, especially Ascaris and Baylisascaris; hookworms, both human and animal; Strongyloides, both human and animal; Enterobius; and the human flariae, primarily Wuchereria and Brugia. Ancylostoma, Ascaris, and Strongyloides reside as adults in the small intestine of their natural hosts, whereas E. Cutaneous larva migrans or creeping eruption occurs when infective larvae of animal hookworms, typically dog and 192 Biosafety in Microbiological and Biomedical Laboratories cat hookworms, penetrate the skin and begin wandering. Ascaris lumbricoides infection is endemic in tropical and subtropical regions of the world. Unembryonated eggs passed in the stool require two to three weeks to become infectious, and Ascaris eggs are very hardy in the environment. Ingestion of the infective eggs or skin penetration by infective larvae are the primary hazards to laboratory staff and animal care personnel. Caution should be used even when working with formalin-fxed stool samples because ascarid eggs can remain viable and continue to develop to the infective stage in formalin. Strongyloides stercoralis is of particular concern to immuno-suppressed persons because potentially life-threatening systemic hyperinfection can occur. Arthropods infected with flarial parasites pose a potential hazard to laboratory personnel. Risk assessment for Cryptosporidium: a hierarchical Bayesian analysis of human dose response data. Laboratory Safety and Containment Recommendations the necessity of using embryonated eggs or cell culture techniques for the propagation of C. Exposure to naturally infected, often asymptomatic, sheep and their birth products is a documented hazard to personnel. Rickettsiae are primarily associated with arthropod vectors in which they may exist as endosymbionts that infect mammals, including humans, through the bite of infected ticks, lice, or feas. All were believed to have been acquired because of exposure to infectious aerosols. Epidemic typhus is unusual among rickettsiae in that humans are considered the primary host. Transmission is by the human body louse; thus, outbreaks are now associated with breakdowns of social conditions. The various spotted fever group rickettsiae are limited geographically, probably by the distribution of the arthropod vector, although specifc spotted fever group rickettsiae are found on all continents. Special Issues Medical Response Under natural circumstances, the severity of disease caused by rickettsial agents varies considerably. However, delay in instituting appropriate chemotherapy may result in debilitating or severe acute disease ranging from increased periods of convalescence in typhus and scrub typhus to death in R. The key to reducing the severity of disease from laboratory-associated infections is a reliable medical response which includes: 1) round-the-clock availability of an experienced medical offcer; 2) indoctrination of all personnel on the potential hazards of working with rickettsial agents and advantages of early therapy; 3) a reporting system for all recognized overt exposures and accidents; 4) the reporting of all febrile illnesses, especially those associated with headache, malaise, and prostration when no other certain cause exists; and 5) an open and non-punitive atmosphere that encourages reporting of any febrile illness. Outbreaks of a previously unrecognized paramyxovirus, at frst called equine morbillivirus, later named Hendra virus, occurred in horses in Australia in 1994 and 1995. During 1998 1999, an outbreak of illness caused by a similar but distinct virus, now known as Nipah virus, occurred in Malaysia and Singapore. Occupational Infections No laboratory-acquired infections are known to have occurred because of Hendra or Nipah virus exposure; however, three people in close contact with ill horses developed encephalitis or respiratory disease and two died. In the outbreaks in Malaysia and Singapore, viral antigen was found in central nervous system, kidney and lung tissues of fatal human cases26 and virus was present in secretions of patients, albeit at low levels. However, hepatitis A is a documented hazard in animal handlers and others working with naturally or experimentally infected chimpanzees and other nonhuman primates. Special Issues Vaccines A licensed inactivated vaccine against hepatitis A is available. Occupational Infections Hepatitis B has been one of the most frequently occurring laboratory-associated infections, and laboratory workers are recognized as a high-risk group for acquiring such infections. Parenteral inoculation, droplet exposure of mucous membranes, and contact exposure of broken skin are the primary laboratory hazards. Gloves should be worn when working with 204 Biosafety in Microbiological and Biomedical Laboratories infected animals and when there is the likelihood of skin contact with infectious materials. B virus is the only member of the family of simplex herpesviruses that can cause zoonotic infections. There remains an approximate 20% mortality in the absence of timely treatment with antiviral agents. Cases prior to 1970 were not treated with antiviral agents because none were available. Morbidity and mortality associated with zoonotic infection results from invasion of the central nervous system, resulting in ascending paralysis ultimately with loss of ability to sustain respiration in the absence of mechanical ventilation. From 1987-2004, fve additional fatal infections bring the number of lethal infections to 29 since the discovery of B virus in 1933. Mucosal secretions (saliva, genital secretions, and conjunctival secretions) are the primary body fuids associated with risk of B virus transmission. However, Agent Summary Statements: Viral Agents 205 feces, urine or other fuids may be contaminated with virus shed from mucosal fuids. Cases of B virus have also been reported after exposure to monkey cell cultures and to central nervous system tissue. In most documented cases of B virus zoonosis, virus was not recovered from potential sources except in four cases, making speculations that some macaque species may be safer than others unfounded. The loss of fve lives in the past two decades underscores that B virus infections have a low probability of occurrence, but when they do occur it is with high consequences. Immediate and thorough cleansing following bites, scratches, splashes, or contact with potential fomites in high-risk areas appears to be helpful in prevention of B virus infections. In these species the virus causes vesicular lesions on the tongue and lips, and sometimes of the skin. Asymptomatic B virus shedding accounts for most transmission among monkeys and human workers, but those working in the laboratory with potentially infected cells or tissues from macaques are also at risk. Zoonotically infected humans should be cautioned about autoinoculation of other susceptible sites when shedding virus during acute infection. All macaques regardless of their origin should be considered potentially infected. Guidelines are available for safely working with macaques and should be consulted. Therapy with intravenous acyclovir and/or ganciclovir in documented B virus infections is also important in reduction of morbidity following B virus zoonotic infection. In approximately 10% of infections, overt illness marked by fever and malaise occurs. Workers without contact with risk group patients were infected no more frequently than the control group. Containment recommendations for herpesvirus simiae (B-virus, Monkey B virus) are described in the preceding agent summary statement. Special Issues Vaccine A live, attenuated vaccine for varicella zoster is licensed and available in the United States. In the event of a laboratory exposure to a non-immune individual, varicella vaccine is likely to prevent or at least modify disease. The two most important features of infuenza are the epidemic nature of illness and the mortality that arises from pulmonary complications of the disease. Infuenza A is further classifed into subtypes by the surface glycoproteins that possess either hemagglutinin (H) or neuraminidase (N) activity. New subtypes are responsible for pandemics and can result from reassortment of human and avian infuenza virus genes. Infuenza viral infections, with different antigenic subtypes, occur naturally in swine, horses, mink, seals and in many domestic and wild avian species. Interspecies transmission and reassortment of infuenza A viruses have been reported to occur among humans and wild and domestic fowl. The human infuenza viruses responsible for the 1918, 1957 and 1968 pandemics contained gene segments closely related to those of avian infuenza viruses. Agent Summary Statements: Viral Agents 211 Natural Modes of Infection Airborne spread is the predominant mode of transmission especially in crowded, enclosed spaces. Infuenza viruses may be disseminated in multiple organs in some infected animal species.

A slow discount glyset 50mg line, continuous quality glyset 50 mg, low-dose infusion is preferable to repeated bolus administra tion buy discount glyset 50 mg on line, because the dose can be titrated to the desired effect purchase generic glyset online, and accidental administration of large boluses of epinephrine can be avoided order 50mg glyset visa. However purchase generic glyset pills, no data support the usefulness of corticosteroids alone in treat ing anaphylaxis, and therefore they should not be administered in lieu of treatment with epinephrine and should be considered as adjunctive therapy. All patients showing signs and symptoms of systemic anaphylaxis, regardless of sever ity, should be observed for several hours in an appropriate facility, even after remission of immediate symptoms. More aggressive therapy with epinephrine may override receptor blockade in some patients. Vaccine dosages given to term infants should not be reduced or divided when given to preterm or low birth weight infants. Preterm and low birth weight infants tolerate most childhood vaccines as well as do term infants. However, these postimmunization cardiorespiratory events do not appear to have a detrimental effect on the clinical course of immunized infants. Medically stable preterm infants who remain in the hospital at 2 months of chronologic age should be given all inactivated vaccines recommended at that age (see Recommended Immunization Schedule for Persons Aged 0 Through 18 Years [ redbook. The same volume of vaccine used for term infants is appropriate for medically stable preterm infants. The number of injections of other vaccines at 2 months of age can be minimized by using combination vaccines. Because recommended parenteral vaccines are inactivated, any interval between doses of individual vaccines is acceptable. However, to avoid super imposing local reactions, 2-week intervals may be reasonable. Revalidation of the Score for Neonatal Acute Physiology in the Vermont Oxford Network. Only monovalent hepatitis B vaccine should be used for preterm or term infants younger than 6 weeks. Administration of a total of 4 doses of hepatitis B vaccine is permitted when a combina tion vaccine containing hepatitis B vaccine is administered after the birth dose. Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine should be administered to all pregnant women (optimally between weeks 27 and 36 of gestation to yield high antibody levels in the infant) during every preg nancy. Tdap should be administered immediately postpartum for women who never have received a previous dose of Tdap. Health care personnel caring for pregnant women and infants and household contacts and child care providers of all infants who have not previ ously received Tdap should be targeted for vaccination. A single dose of Tdap is recom mended for all nonpregnant adolescents as well as nonpregnant adults of any age (see Pertussis, p 608). Palivizumab use does not interfere with the immune response to routine childhood immunizations. For women never previously vaccinated with Tdap, if Tdap is not administered during the current pregnancy, Tdap should be administered immediately postpartum. If a Td booster is indicated for wound management during pregnancy, Tdap should be given if the woman has not already received Tdap during the current pregnancy (see Pertussis, p 608). In resource-limited countries with a high incidence of neonatal tetanus, Td vac cine routinely is administered during pregnancy without evidence of adverse effects and with striking decreases in the occurrence of neonatal tetanus. Although only a theoretical risk to the fetus exists with a live-virus vaccine administered to the pregnant 1 Because measles, mumps, rubella, and vari cella vaccines are contraindicated for pregnant women, efforts should be made to immunize women without evidence of immunity against these illnesses before they become pregnant or in the immediate postpartum period. Although of theoretical concern, no case of embryopathy caused by live rubella vaccine has been reported. However, a rare theoretical risk of embryopathy from inadvertent rubella vaccine administration cannot be excluded. Through March 2012, more than 850 women (more than 170 of whom were known to be seronegative before vaccina tion) were enrolled prospectively in the Pregnancy Registry and had known pregnancy outcomes. The registry was discontinued for new enrollments in October 2013, because statistically more robust data on the risk of congenital varicella syndrome would likely not accrue given the diminishing seronegative population (because of implementation of universal vaccination) and diminished inadvertent immunization during pregnancy (because of completion of vaccination at a younger age). A pregnant woman in the household is not a contraindication for varicella immu nization of a child or other household member. Transmission of vaccine virus from an immunocompetent vaccine recipient to a susceptible person has been reported only rarely, and only when a vaccine-associated rash develops in the vaccine recipi ent (see Varicella-Zoster Infections, p 846). It should not be administered to pregnant women, and pregnancy should be avoided for 1 month following a dose. Pregnant women and nursing mothers should avoid or postpone travel to an area where there is risk of yellow fever. No infor mation is available on the safety of any of the typhoid vaccines in pregnancy; it there 1 fore is prudent on theoretical grounds to avoid vaccinating pregnant women. Meningococcal conju gate vaccine can be given to a pregnant woman when there is increased risk of disease, such as during epidemics or before travel to an area with hyperendemic infection. Initiation of the vaccine series should be delayed until after completion of the pregnancy. If a woman is determined to be pregnant after initiating the immunization series, the remainder of the 3-dose regimen should be delayed until after completion of the pregnancy. If a vac cine dose has been administered during pregnancy, no intervention is needed. Rabies vaccine should be given to pregnant women after exposure to rabies under the same circumstances as nonpregnant women. No associa tion between rabies immunization and adverse fetal outcomes has been reported. If the risk of exposure to rabies is substantial, preexposure prophylaxis also may be indicated. Anthrax vaccine is inactivated and has no theoretical risk to the fetus, but the vaccine has not been evaluated for safety in pregnant women, so it should be avoided unless in a postevent situation with a high risk of exposure (see Anthrax, p 234). Primary disorders of the immune system generally are inherited, usually as single-gene disorders; can involve any part of the immune defenses, including B-lymphocyte (humoral) immunity, T-lymphocyte (cell)-mediated immunity, complement and phagocytic function, and innate immunity; 2 and share the common feature of increased susceptibility to infection. Additional vaccines not given universally are indicated for children with certain con ditions. Immunocompromised patients should avoid contact with people who develop skin lesions after receipt of varicella or zoster vac cines until lesions clear. Inactivated vaccine administration can be deferred temporarily until corticosteroids are discontinued if the hiatus is expected to be brief and adherence to return appointment is likely. Application of low-potency topical corticosteroids to localized areas on the skin; admin istration by aerosolization; application on conjunctiva; or intraarticular, bursal, or tendon injections of corticosteroids usually do not result in immunosuppression that would con traindicate administration of live-virus vaccines. Children who are receiving only maintenance physiologic doses of corticosteroids can receive live-virus vaccines. Some experts, however, would delay immunization with live-virus vaccines until 2 weeks after discontinuation. These chil dren should not be given live-virus vaccines, except in special circumstances. These agents often are used in combination with other immunosuppressive drugs, such as methotrexate or corticosteroids. Vaccination status should be assessed pretreatment, and recommended vaccines should be administered with timing as for planned corticosteroid use (see Timing of Vaccines). Patients 12 months or older who have not received hepatitis A vaccine (HepA), did not complete the vacci nation series, or who are seronegative should receive the HepA vaccine series. Household members of these patients should be counseled about risks of infection and should have vaccination status made current. All infants, children, adolescents, and adults with asplenia, regardless of the reason for the asplenic state, have an increased risk of fulminant septicemia, especially associated with encapsulated bacteria, which is associated with a high mortality rate. In comparison with immunocompetent children who have not undergone splenectomy, the incidence of and mortality rate from septice mia are increased in children who have had splenectomy after trauma and in children with sickle cell disease by as much as 350-fold, and the rate may be even higher in chil dren who have had splenectomy for thalassemia. The risk of invasive bacterial infection is higher in younger children than in older children, and the risk may be greater during the years immediately after surgical splenectomy. Streptococcus pneumoniae is the most common pathogen causing septicemia in children with asplenia. Those with functional or anatomic asplenia also are at increased risk of fatal malaria and severe babesiosis. Immunization Pneumococcal conjugate and polysaccharide vaccines are vital for all children with asple nia (see Pneumococcal Infections, p 626). A second dose should be administered 5 years later (see Pneumococcal Infections, p 626). Previously unimmunized children with asplenia younger than 5 years should receive Hib vaccine according to the catch-up schedule. Unimmunized children 5 years or older should receive a single dose of Hib vaccine. When surgical splenectomy is planned, immunization status for Hib, pneumococcus, and meningococcus should be ascertained, and all indicated vaccines should be adminis tered at least 2 weeks before surgery. If splenectomy is emergent, or vaccination was not performed before splenectomy, indicated vaccines should be initiated as soon as possible 2 weeks or more after surgery. Management options include postponement of splenectomy for as long as possible in people with congenital hemolytic anemia, preservation of accessory spleens, performance of partial splenectomy for benign tumors of the spleen, conservative (non operative) management of splenic trauma, or when feasible, repair rather than removal. Antimicrobial Agents Daily antimicrobial prophylaxis against pneumococcal infections is recommended for many children with asplenia, regardless of immunization status. Less agreement exists about the need for prophylaxis for children who have had splenec tomy after trauma. In general, antimicrobial prophylaxis (in addition to immunization) should be considered for all children with asplenia younger than 5 years of age and for at least 1 year after splenectomy at any age. On the basis of a multicenter study, prophylactic penicillin can be discontinued at 5 years of age in children with sickle cell disease who are receiving regular medical attention, are fully immunized, and have not had a severe pneumococcal infection or surgical splenec tomy. The appropriate duration of prophylaxis for children with asplenia attributable to other causes is unknown. For antimicrobial prophylaxis, oral penicillin V (125 mg, twice a day, for children younger than 3 years; and 250 mg, twice a day, for children 3 years or older) is recom mended. A sub stantial percentage of pneumococcal isolates have intermediate or high-level resistance to penicillin, resistance to macrolides and azalides, or both. When antimicrobial prophylaxis is used, these limitations must be stressed to parents and patients, who should be made aware that all febrile illnesses potentially are serious in children with asplenia and that immediate medical attention should be sought because the initial signs and symptoms of fulminant septicemia can be subtle. Likewise, medical attention should be sought for asplenic patients who suffer animal bites. Parenteral antimicrobial therapy also is given in the periopera tive period for cochlear implantation and reparative neurosurgical procedures. Infants and children with a personal or family history of seizures of any etiology might be at greater risk of having a febrile seizure after receipt of one of these vaccines compared with children without such histories. No evidence indicates that febrile seizures cause permanent brain damage or epilepsy, aggravate neurologic disorders, or affect the prognosis for children with underlying disorders. In the case of pertussis immunization during infancy, vaccine administration could coincide with or hasten the recognition of a disorder associated with seizures, such as infantile spasms or severe myoclonic epilepsy of infancy, which could cause confusion about the role of pertussis immunization. Hence, pertussis immunization in infants with a history of recent seizures generally should be deferred until a progressive neurologic disorder is excluded or the cause of the earlier seizure has been determined. The nature of seizures and related neurologic status are more likely to have been established in children by the age of 12 months. Postimmunization seizures in these children are uncommon, and if they occur usually are febrile in origin, have a benign outcome, and are not likely to be confused with manifestations of a previously unrecognized neurologic disorder. Chronic diseases may make children more susceptible to the severe manifestations and complications of common infections. However, live-virus vaccines are contraindi cated in children with severe immunologic disorders, including children receiving chronic immunosuppressive therapy (see Immunocompromised Children, p 74). All children with chronic liver disease are at risk of severe clinical manifestations of acute infection with hepatitis viruses and should receive hepatitis A (HepA) and hepatitis B (HepB) vaccines on a catch-up schedule if they have not received vaccines routinely (see Hepatitis A, p 391, and Hepatitis B, p 400). Siblings of children with chronic diseases and children in households of adults with chronic diseases should receive recommended vaccines, including both live and inactivated vaccines ( Immunization in American Indian/Alaska Native Children Although indigenous populations worldwide have high morbidity and mortality from infectious diseases, including vaccine-preventable infections, all indigenous populations are not the same ( nc. Little information is known about relative risks of vaccine-preventable and other infectious diseases in indi viduals not living on reservations. Availability of more than one Hib vaccine product in a clinic has been shown to lead to errors in vaccine administration. It is unclear whether an apparent increase in Hia disease is attributable to improved surveillance, higher attention since the dramatic decrease in Hib disease, or replacement. To maintain these low rates, special efforts should be made to ensure catch-up hepatitis B immunization of previously unimmunized adolescents. The risk of exposure to vaccine-preventable infections may be increased, and additional immunizations against infections not given routinely in the United States, such as typhoid disease, yellow fever, and Japanese encephalitis, may be indicated. Yellow fever vaccine should be given to children 9 months or older who will reside in areas where yellow fever is endemic in South America and Africa. Families should be educated about the risk of rabies in resource-limited countries. Children should be educated to avoid contact with animals and to report any bites or scratches from animals while abroad. As a result, many adolescents do not receive routine preventive care that provides opportunities for immunization. To ensure age-appropriate immunization, all youth should have a routine appoint ment at 11 through 12 years of age for administration of appropriate vaccines and to 1 provide comprehensive preventive health care. The 11 through 12-year age platform for administration of these 3 vaccines was chosen to offer the best protection against these potentially serious and life-threating infections. Lapses in the immunization schedule are common among adolescents and do not necessitate reinitia tion of the entire series or extra doses of any individual dose that was valid. Accordingly, school and college health services should establish a system to ensure that all students are protected against vaccine-preventable diseases. Because adolescents and young adults commonly travel internationally, their immu nization status and travel plans should be reviewed 2 or more months before depar ture to allow time to administer any needed vaccines (see International Travel, p 101). In addition, pediatricians should help facilitate transfer of immunization information to schools and colleges when applica ble.