By U. Kor-Shach. Metropolitan College of New York.

Lead is slowly but consistently absorbed via the 52 Toxicology respiratory and gastrointestinal tracts purchase 10 mg lioresal with amex gastric spasms. Lead exerts multi systemic toxic effects through at least three mechanisms by order 10 mg lioresal overnight delivery muscle relaxants kidney failure; o Inhibiting enzyme activity (e. Lead interference with the biosynthesis of heme The sign and symptoms of lead poisoning may include anorexia, apathy, behavioral changes, persistent vomiting, convulsions (acute poisoning) & ataxia, wrist & ankle drop, chronic nephritis (chronic poisoning) Laboratory findings A. It is not present in iron deficiency anemia so it is valuable for differentiating the two forms of anemia. B) Serum Lead level Levels of 30-60µg/dl are regarded as significant for lead toxicity. Levels below the toxic range do not rule out toxicity because 90% of lead is stored in bone. Unexpectedly high lead levels may be due to contamination of the blood specimen with lead prior to laboratory analysis. Protoporphyrin accumulates as a result of the lead inhibition of the enzyme ferrochelases, which binds to porphyrin, forming hemoglobin. Lead inhibition of the enzyme coproporphyrinogen oxidase has been proposed as a cause for increased coproporphyrin. Spot 50 µl of acidified solution on to phase-separating filter- paper and add 50 µl of sodium rhodizonate solution. However, the test is not specific: barium salts give a brown colour and a number of other metals also give coloured complexes. Sensitivity Lead, 2 mg/l Quantitative tests Principle 56 Toxicology Whole blood that represents calibrators, controls, or victim specimens is mixed with ammonium phosphate and Triton X-100 to prepare it for graphite furnace atomic absorption analysis. The final step of analysis causes vaporization of lead, which absorbs energy at the 283. Absorbance of energy at this wavelength is specific for lead and proportional to its concentration. Add 10 µL of matrix modifier to 10µL of each sample and inject into the L’vov platform. Repeat the analysis at an appropriate dilution for any specimen with an absorbance greater than that of the high concentration calibrator Calculation 1. Perform a best-fit regression analysis of the calibrator concentrations versus the respective absorbance peak area to define the calibration curve. If the results among duplicates vary by more than 10%, sample contamination during processing is likely to have occurred. Hydrocarbons are found alone or incombination with others in a wide variety of commercial products ubiquitous around the home or work place. Lighter fluid, paint thinners, &removers, some furniture polishes, cleaning agents, solvents, various automotive products & 58 Toxicology ordinary fuels are common examples. These agents were the most frequently involved substances in human exposures, accounting for almost 5% of all poisoning. The overall mortality rate for accidental ingestion of these agents is difficult to estimate but may approach 0. The most common substances reported in toxic ingestions are gasoline, kerosene, mineral seal oil preparations, &lighter fluid. Most victims who are exposed to hydrocarbon develop pulmonary symptoms due to aspiration pneumonitis.

Side Effects 133 Side Effects Guillain-Barré Syndrome is seen as the most dangerous side effect of influenza vaccines order lioresal 25mg otc spasms below sternum, aside from manifestations of egg allergy purchase lioresal 10 mg visa muscle relaxant veterinary. The most frequent side effects are pain, redness, and swelling at the injection site (10-64 %) lasting 1-2 days, and systemic side effects such as headache, fever, mal- aise, and myalgia in about 5 % of vaccinees (Belshe 2005, Musana 2004, Potter 2004). These side effects are largely due to a local immune response, with inter- feron production leading to systemic effects. Local side effects are more common with whole virus vaccines than subunit or split vaccines, and also more common with intradermal vaccination than intramuscular vaccination. Since the inactivated vaccines do not contain live virus, they cannot cause influenza infection – often respiratory illness is incorrectly attributed to influenza vaccination. Live attenuated virus vaccines do contain live virus; however, side effects are rare, with a runny nose, congestion, sore throat, and headache being the most commonly reported symptoms, with occasional abdominal pain, vomiting, and myalgia (Musana 2004). They are not recommended for use in children below the age of 5 years, although a study by Piedra et al. Controversies have arisen around the possibility of exacerbated asthma in children between 18-34 months of age (Bergen 2004, Black 2004, Glezen 2004). L – likelihood of transmission to high risk persons – healthcare workers and care providers can transmit influenza to patients, as can other employees in institutions serving the high risk population groups, as well as people living with individuals at high risk. U – underlying medical conditions such as diabetes mellitus, chronic heart or lung disease, pregnancy, cancer, immunodeficiency, renal disease, organ transplant re- cipients, and others. A – age > 65 years, or between 6-23 months of age Since the risk of influenza rises linearly from the age of 50 years, some promote the vaccination of those aged between 50 and 64 in addition to those above 65 years of age. In a study of health professional attitudes to such a policy in England, both sides were equally divided (Joseph 2005). In the era of a potentially pending pandemic, other groups also have importance for targeting – poultry workers in the Far East are being vaccinated to prevent infection with circulating human influenza strains. This vaccine will not protect against avian influenza strains, but will help prevent dual infection, if infection with avian influ- enza does occur, thereby reducing opportunities for reassortment of two strains in one human host. For the same reason, travelers to areas where avian influenza is present are advised to be vaccinated against human influenza (Beigel 2005). Elderly, non-institutionalized individuals with chronic heart or lung dis- eases, metabolic or renal disease, or immunodeficiencies. Other groups defined on the basis of national data and capacities, such as contacts of high-risk people, pregnant women, healthcare workers and others with key func- tions in society, as well as children aged 6–23 months. Out-of-home caregivers and household contacts of children aged 0-23 months South Africa has the following guidelines (summarised from Schoub 2005), divid- ing the population into 4 groups who may receive the vaccine –! Recommendation for Use 135 o Children with chronic pulmonary or cardiac diseases as well as immunosuppressed children. Category 2 – Contacts of high-risk persons - healthcare workers, caregiv- ers of the elderly and high-risk patients, and persons living with high risk persons. People six months of age and older with chronic illnesses requiring regular medical follow-up or hospitalisation in the previous year! People six months of age and older with chronic illnesses of the pulmonary or circulatory systems (except asthma)! Children and teenagers aged six months to 18 years on long-term aspirin therapy (because aspirin treatment puts them at risk of Reye’s syndrome if they develop a fever)!

In European pig populations buy lioresal 10 mg free shipping spasms sternum, avian-like H1N1 viruses are highly prevalent (Heinen 2002) and an H1N2 virus generic 10mg lioresal mastercard infantile spasms 6 weeks, a human-avian reassortant vi- rus, Þrst isolated in the U. A H9N2 virus of avian provenance is moderately prevalent in swine populations in the East of China (Xu 2004). In addition to swine, marine mammals and horses have been shown to acquire influenza A viruses from avian sources (Guo 1992, Ito 1999). Natural infection with H5N1 was described in tigers and other large cats in a zoo in Thailand after the animals were fed with virus-positive chicken carcasses (Keawcharoen 2004, Quirk 2004, Amosin 2005). In 2004, 3,000 serum samples obtained from free roaming pigs in Vietnam were tested serologically for evidence of exposure to the H5N1 influenza virus (Choi 2005). In experimental infections, it was shown that pigs can be infected with H5N1 viruses isolated in Asia in 2004 from human and avian sources. A mild cough and elevated body temperature were the only symptoms observed for four days post infection. Peak viral titres from nasal swabs were found on day 2 post infection, but none of the experimentally infected animals transmitted the infection to contact pigs. None of the avian and human H5N1 viruses tested were readily transmitted between pigs under experimental conditions (Choi 2005). Based on these observations, pigs probably do not currently play an important role in the epidemiology of the Asian lineage H5N1. An outbreak of the highly pathogenic H7N7 avian influenza in poultry, in the Neth- erlands, Belgium and Germany in Spring 2003, caused infection and mild illness, predominantly conjunctivitis, in 89 poultry workers exposed to infected animals and carcasses (Koopmans 2004). The infection of one veterinarian caused an acute respiratory distress syndrome and took a fatal course (Fouchier 2004). In addition, during the Dutch outbreak, H7N7 infection was virologically and serologically con- firmed in several household contacts, four of which showed conjunctivitis (Du Ry van Beest Holle 2005). Avian influenza viruses have never been detected in rats, rabbits and various other mammals present at live bird markets in Hong Kong where 20 % of the chickens were found positive for the Asian lineage H5N1 (Shortridge 1998). Most outbreaks were geographically limited, with only five resulting in significant spread to numerous farms, and only one which spread internationally. To date, all outbreaks of the highly pathogenic form have been caused by influenza A viruses of the subtypes H5 and H7. In the past outbreaks, illegal trade or movements of infected live birds or their un- processed products, and unintended mechanical passing-on of virus through human movements (travellers, refugees, etc. The simultaneous occurrence in several countries of large epidemics of highly pathogenic H5N1 influenza in domestic poultry is unprecedented. Despite the culling and the pre-emptive destruction of some 150 million birds, H5N1 is now considered endemic in many parts of Indonesia and Vietnam and in some parts of Cambodia, China, Thailand, and possibly also the Lao People’s Democratic Republic. In April 2005, yet another level of the epizootic was reached, when, for the Þrst time, the H5N1 strain obtained access to wild bird populations on a larger scale Economic Consequences 67 (Chen 2005, Liu 2005). At Lake Qinghai in North Western China several thousands of bar-headed geese, a migratory species, succumbed to the infection. When, in the summer and early autumn of 2005, H5N1 outbreaks were reported for the Þrst time from geographically adjacent Mongolia, Kazakhstan, and Southern Siberia, migratory birds were suspected of spreading the virus. Further outbreaks along and between overlapping migratory flyways from inner Asia towards the Middle East and Africa hit Turkey, Romania, Croatia, and the Crimean peninsula in late 2005.

Anatomical dead space refers to the air within the respiratory structures that never participates in gas exchange buy 25 mg lioresal with mastercard muscle relaxant 10mg, because it does not reach functional alveoli generic 25mg lioresal with amex spasms after surgery. Respiratory rate is the number of breaths taken per minute, which may change during certain diseases or conditions. Both respiratory rate and depth are controlled by the respiratory centers of the brain, which are stimulated by factors such as chemical and pH changes in the blood. These changes are sensed by central chemoreceptors, which are located in the brain, and peripheral chemoreceptors, which are located in the aortic arch and carotid arteries. A rise in carbon dioxide or a decline in oxygen levels in the blood stimulates an increase in respiratory rate and depth. Dalton’s law states that each specific gas in a mixture of gases exerts force (its partial pressure) independently of the other gases in the mixture. Henry’s law states that the amount of a specific gas that dissolves in a liquid is a function of its partial pressure. The greater the partial pressure of a gas, the more of that gas will dissolve in a liquid, as the gas moves toward equilibrium. Gas molecules move down a pressure gradient; in other words, gas moves from a region of high pressure to a region of low pressure. The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. In contrast, the partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli. Ventilation is the process that moves air into and out of the alveoli, and perfusion affects the flow of blood in the capillaries. Both are important in gas exchange, as ventilation must be sufficient to create a high partial pressure of oxygen in the alveoli. If ventilation is insufficient and the partial pressure of oxygen drops in the alveolar air, the capillary is constricted and blood flow is redirected to alveoli with sufficient ventilation. External respiration refers to gas exchange that occurs in the alveoli, whereas internal respiration refers to gas exchange that occurs in the tissue. These cells contain a metalloprotein called hemoglobin, which is composed of four subunits with a ring-like structure. When all of the heme units in the blood are bound to oxygen, hemoglobin is considered to be saturated. An oxygen–hemoglobin saturation/dissociation curve is a common way to 1080 Chapter 22 | The Respiratory System depict the relationship of how easily oxygen binds to or dissociates from hemoglobin as a function of the partial pressure of oxygen. At the same time, once one molecule of oxygen is bound by hemoglobin, additional oxygen molecules more readily bind to hemoglobin. Other factors such as temperature, pH, the partial pressure of carbon dioxide, and the concentration of 2,3-bisphosphoglycerate can enhance or inhibit the binding of hemoglobin and oxygen as well. Fetal hemoglobin has a different structure than adult hemoglobin, which results in fetal hemoglobin having a greater affinity for oxygen than adult hemoglobin. Carbon dioxide is transported in blood by three different mechanisms: as dissolved carbon dioxide, as bicarbonate, or as carbaminohemoglobin. For this conversion, carbon dioxide is combined with water with the aid of an enzyme called carbonic anhydrase. This combination forms carbonic acid, which spontaneously dissociates into bicarbonate and hydrogen ions. As bicarbonate builds up in erythrocytes, it is moved across the membrane into the plasma in exchange for chloride ions by a mechanism called the chloride shift. At the pulmonary capillaries, bicarbonate re-enters erythrocytes in exchange for chloride ions, and the reaction with carbonic anhydrase is reversed, recreating carbon dioxide and water. The partial pressures of carbon dioxide and oxygen, as well as the oxygen saturation of hemoglobin, influence how readily hemoglobin binds carbon dioxide.